Merge branch 'archwiki'

Conflicts:
	extensions/FluxBBAuthPlugin.php
	extensions/SyntaxHighlight_GeSHi/README
	extensions/SyntaxHighlight_GeSHi/SyntaxHighlight_GeSHi.class.php
	extensions/SyntaxHighlight_GeSHi/SyntaxHighlight_GeSHi.i18n.php
	extensions/SyntaxHighlight_GeSHi/SyntaxHighlight_GeSHi.php
	extensions/SyntaxHighlight_GeSHi/geshi/docs/CHANGES
	extensions/SyntaxHighlight_GeSHi/geshi/docs/THANKS
	extensions/SyntaxHighlight_GeSHi/geshi/docs/TODO
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/AbstractClass.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/AbstractClass_logo.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/AbstractMethod.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/AbstractPrivateClass.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/AbstractPrivateClass_logo.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/AbstractPrivateMethod.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Class.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Class_logo.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Constant.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Constructor.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Destructor.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Function.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Global.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/I.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Index.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Interface.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Interface_logo.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/L.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Lminus.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Lplus.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Method.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Page.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Page_logo.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/PrivateClass.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/PrivateClass_logo.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/PrivateMethod.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/PrivateVariable.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/StaticMethod.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/StaticVariable.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/T.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Tminus.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Tplus.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/Variable.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/blank.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/class_folder.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/file.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/folder.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/function_folder.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/next_button.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/next_button_disabled.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/package.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/package_folder.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/previous_button.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/previous_button_disabled.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/private_class_logo.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/tutorial.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/tutorial_folder.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/api/media/images/up_button.png
	extensions/SyntaxHighlight_GeSHi/geshi/docs/geshi-doc.html
	extensions/SyntaxHighlight_GeSHi/geshi/docs/geshi-doc.txt
	extensions/SyntaxHighlight_GeSHi/geshi/geshi.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/4cs.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/6502acme.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/6502kickass.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/6502tasm.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/68000devpac.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/abap.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/actionscript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/actionscript3.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/ada.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/algol68.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/apache.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/applescript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/apt_sources.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/asm.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/asp.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/autoconf.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/autohotkey.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/autoit.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/avisynth.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/awk.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/bascomavr.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/bash.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/basic4gl.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/bf.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/bibtex.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/blitzbasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/bnf.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/boo.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/c.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/c_loadrunner.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/c_mac.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/caddcl.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/cadlisp.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/cfdg.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/cfm.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/chaiscript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/cil.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/clojure.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/cmake.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/cobol.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/coffeescript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/cpp-qt.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/cpp.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/csharp.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/css.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/cuesheet.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/d.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/dcs.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/delphi.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/diff.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/div.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/dos.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/dot.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/e.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/ecmascript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/eiffel.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/email.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/epc.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/erlang.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/euphoria.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/f1.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/falcon.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/fo.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/fortran.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/freebasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/fsharp.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/gambas.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/gdb.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/genero.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/genie.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/gettext.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/glsl.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/gml.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/gnuplot.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/go.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/groovy.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/gwbasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/haskell.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/hicest.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/hq9plus.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/html4strict.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/html5.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/icon.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/idl.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/ini.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/inno.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/intercal.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/io.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/j.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/java.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/java5.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/javascript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/jquery.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/kixtart.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/klonec.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/klonecpp.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/latex.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/lb.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/lisp.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/llvm.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/locobasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/logtalk.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/lolcode.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/lotusformulas.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/lotusscript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/lscript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/lsl2.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/lua.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/m68k.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/magiksf.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/make.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/mapbasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/matlab.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/mirc.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/mmix.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/modula2.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/modula3.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/mpasm.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/mxml.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/mysql.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/newlisp.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/nsis.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/oberon2.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/objc.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/objeck.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/ocaml-brief.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/ocaml.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/oobas.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/oracle11.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/oracle8.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/oxygene.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/oz.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/pascal.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/pcre.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/per.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/perl.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/perl6.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/pf.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/php-brief.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/php.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/pic16.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/pike.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/pixelbender.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/pli.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/plsql.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/postgresql.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/povray.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/powerbuilder.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/powershell.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/proftpd.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/progress.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/prolog.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/properties.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/providex.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/purebasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/pycon.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/python.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/q.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/qbasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/rails.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/rebol.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/reg.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/robots.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/rpmspec.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/rsplus.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/ruby.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/sas.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/scala.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/scheme.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/scilab.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/sdlbasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/smalltalk.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/smarty.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/sql.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/systemverilog.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/tcl.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/teraterm.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/text.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/thinbasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/tsql.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/typoscript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/unicon.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/uscript.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/vala.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/vb.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/vbnet.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/verilog.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/vhdl.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/vim.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/visualfoxpro.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/visualprolog.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/whitespace.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/whois.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/winbatch.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/xbasic.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/xml.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/xorg_conf.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/xpp.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/yaml.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/z80.php
	extensions/SyntaxHighlight_GeSHi/geshi/geshi/zxbasic.php

22 files changed, 3194 insertions, 2041 deletions

diff --git a/includes/filebackend/FSFile.php b/includes/filebackend/FSFile.php
index e07c99d4..8f0a1334 100644
--- a/includes/filebackend/FSFile.php
+++ b/includes/filebackend/FSFile.php
@@ -28,11 +28,12 @@
  */
 class FSFile {
 	protected $path; // path to file
+	protected $sha1Base36; // file SHA-1 in base 36
 
 	/**
 	 * Sets up the file object
 	 *
-	 * @param $path string Path to temporary file on local disk
+	 * @param string $path Path to temporary file on local disk
 	 * @throws MWException
 	 */
 	public function __construct( $path ) {
@@ -86,8 +87,8 @@ class FSFile {
 
 	/**
 	 * Guess the MIME type from the file contents alone
-	 * 
-	 * @return string 
+	 *
+	 * @return string
 	 */
 	public function getMimeType() {
 		return MimeMagic::singleton()->guessMimeType( $this->path, false );
@@ -97,14 +98,14 @@ class FSFile {
 	 * Get an associative array containing information about
 	 * a file with the given storage path.
 	 *
-	 * @param $ext Mixed: the file extension, or true to extract it from the filename.
+	 * @param Mixed $ext: the file extension, or true to extract it from the filename.
 	 *             Set it to false to ignore the extension.
 	 *
 	 * @return array
 	 */
 	public function getProps( $ext = true ) {
 		wfProfileIn( __METHOD__ );
-		wfDebug( __METHOD__.": Getting file info for $this->path\n" );
+		wfDebug( __METHOD__ . ": Getting file info for $this->path\n" );
 
 		$info = self::placeholderProps();
 		$info['fileExists'] = $this->exists();
@@ -131,7 +132,7 @@ class FSFile {
 			# Height, width and metadata
 			$handler = MediaHandler::getHandler( $info['mime'] );
 			if ( $handler ) {
-				$tempImage = (object)array();
+				$tempImage = (object)array(); // XXX (hack for File object)
 				$info['metadata'] = $handler->getMetadata( $tempImage, $this->path );
 				$gis = $handler->getImageSize( $tempImage, $this->path, $info['metadata'] );
 				if ( is_array( $gis ) ) {
@@ -140,9 +141,9 @@ class FSFile {
 			}
 			$info['sha1'] = $this->getSha1Base36();
 
-			wfDebug(__METHOD__.": $this->path loaded, {$info['size']} bytes, {$info['mime']}.\n");
+			wfDebug( __METHOD__ . ": $this->path loaded, {$info['size']} bytes, {$info['mime']}.\n" );
 		} else {
-			wfDebug(__METHOD__.": $this->path NOT FOUND!\n");
+			wfDebug( __METHOD__ . ": $this->path NOT FOUND!\n" );
 		}
 
 		wfProfileOut( __METHOD__ );
@@ -170,7 +171,7 @@ class FSFile {
 	/**
 	 * Exract image size information
 	 *
-	 * @param $gis array
+	 * @param array $gis
 	 * @return Array
 	 */
 	protected function extractImageSizeInfo( array $gis ) {
@@ -193,26 +194,33 @@ class FSFile {
 	 * 160 log 2 / log 36 = 30.95, so the 160-bit hash fills 31 digits in base 36
 	 * fairly neatly.
 	 *
+	 * @param bool $recache
 	 * @return bool|string False on failure
 	 */
-	public function getSha1Base36() {
+	public function getSha1Base36( $recache = false ) {
 		wfProfileIn( __METHOD__ );
 
+		if ( $this->sha1Base36 !== null && !$recache ) {
+			wfProfileOut( __METHOD__ );
+			return $this->sha1Base36;
+		}
+
 		wfSuppressWarnings();
-		$hash = sha1_file( $this->path );
+		$this->sha1Base36 = sha1_file( $this->path );
 		wfRestoreWarnings();
-		if ( $hash !== false ) {
-			$hash = wfBaseConvert( $hash, 16, 36, 31 );
+
+		if ( $this->sha1Base36 !== false ) {
+			$this->sha1Base36 = wfBaseConvert( $this->sha1Base36, 16, 36, 31 );
 		}
 
 		wfProfileOut( __METHOD__ );
-		return $hash;
+		return $this->sha1Base36;
 	}
 
 	/**
 	 * Get the final file extension from a file system path
-	 * 
-	 * @param $path string
+	 *
+	 * @param string $path
 	 * @return string
 	 */
 	public static function extensionFromPath( $path ) {
@@ -223,10 +231,9 @@ class FSFile {
 	/**
 	 * Get an associative array containing information about a file in the local filesystem.
 	 *
-	 * @param $path String: absolute local filesystem path
-	 * @param $ext Mixed: the file extension, or true to extract it from the filename.
+	 * @param string $path absolute local filesystem path
+	 * @param Mixed $ext: the file extension, or true to extract it from the filename.
 	 *             Set it to false to ignore the extension.
-	 *
 	 * @return array
 	 */
 	public static function getPropsFromPath( $path, $ext = true ) {
@@ -241,8 +248,7 @@ class FSFile {
 	 * 160 log 2 / log 36 = 30.95, so the 160-bit hash fills 31 digits in base 36
 	 * fairly neatly.
 	 *
-	 * @param $path string
-	 *
+	 * @param string $path
 	 * @return bool|string False on failure
 	 */
 	public static function getSha1Base36FromPath( $path ) {
diff --git a/includes/filebackend/FSFileBackend.php b/includes/filebackend/FSFileBackend.php
index 93495340..6d642162 100644
--- a/includes/filebackend/FSFileBackend.php
+++ b/includes/filebackend/FSFileBackend.php
@@ -46,6 +46,7 @@ class FSFileBackend extends FileBackendStore {
 	protected $fileOwner; // string; required OS username to own files
 	protected $currentUser; // string; OS username running this script
 
+	/** @var Array */
 	protected $hadWarningErrors = array();
 
 	/**
@@ -69,7 +70,7 @@ class FSFileBackend extends FileBackendStore {
 		if ( isset( $config['containerPaths'] ) ) {
 			$this->containerPaths = (array)$config['containerPaths'];
 			foreach ( $this->containerPaths as &$path ) {
-				$path = rtrim( $path, '/' );  // remove trailing slash
+				$path = rtrim( $path, '/' ); // remove trailing slash
 			}
 		}
 
@@ -81,12 +82,6 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::resolveContainerPath()
-	 * @param $container string
-	 * @param $relStoragePath string
-	 * @return null|string
-	 */
 	protected function resolveContainerPath( $container, $relStoragePath ) {
 		// Check that container has a root directory
 		if ( isset( $this->containerPaths[$container] ) || isset( $this->basePath ) ) {
@@ -101,7 +96,7 @@ class FSFileBackend extends FileBackendStore {
 	/**
 	 * Sanity check a relative file system path for validity
 	 *
-	 * @param $path string Normalized relative path
+	 * @param string $path Normalized relative path
 	 * @return bool
 	 */
 	protected function isLegalRelPath( $path ) {
@@ -120,8 +115,8 @@ class FSFileBackend extends FileBackendStore {
 	 * Given the short (unresolved) and full (resolved) name of
 	 * a container, return the file system path of the container.
 	 *
-	 * @param $shortCont string
-	 * @param $fullCont string
+	 * @param string $shortCont
+	 * @param string $fullCont
 	 * @return string|null
 	 */
 	protected function containerFSRoot( $shortCont, $fullCont ) {
@@ -136,7 +131,7 @@ class FSFileBackend extends FileBackendStore {
 	/**
 	 * Get the absolute file system path for a storage path
 	 *
-	 * @param $storagePath string Storage path
+	 * @param string $storagePath Storage path
 	 * @return string|null
 	 */
 	protected function resolveToFSPath( $storagePath ) {
@@ -144,7 +139,7 @@ class FSFileBackend extends FileBackendStore {
 		if ( $relPath === null ) {
 			return null; // invalid
 		}
-		list( $b, $shortCont, $r ) = FileBackend::splitStoragePath( $storagePath );
+		list( , $shortCont, ) = FileBackend::splitStoragePath( $storagePath );
 		$fsPath = $this->containerFSRoot( $shortCont, $fullCont ); // must be valid
 		if ( $relPath != '' ) {
 			$fsPath .= "/{$relPath}";
@@ -152,10 +147,6 @@ class FSFileBackend extends FileBackendStore {
 		return $fsPath;
 	}
 
-	/**
-	 * @see FileBackendStore::isPathUsableInternal()
-	 * @return bool
-	 */
 	public function isPathUsableInternal( $storagePath ) {
 		$fsPath = $this->resolveToFSPath( $storagePath );
 		if ( $fsPath === null ) {
@@ -177,11 +168,7 @@ class FSFileBackend extends FileBackendStore {
 		return $ok;
 	}
 
-	/**
-	 * @see FileBackendStore::doStoreInternal()
-	 * @return Status
-	 */
-	protected function doStoreInternal( array $params ) {
+	protected function doCreateInternal( array $params ) {
 		$status = Status::newGood();
 
 		$dest = $this->resolveToFSPath( $params['dst'] );
@@ -190,27 +177,70 @@ class FSFileBackend extends FileBackendStore {
 			return $status;
 		}
 
-		if ( file_exists( $dest ) ) {
-			if ( !empty( $params['overwrite'] ) ) {
-				$ok = unlink( $dest );
-				if ( !$ok ) {
-					$status->fatal( 'backend-fail-delete', $params['dst'] );
-					return $status;
-				}
-			} else {
-				$status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
+		if ( !empty( $params['async'] ) ) { // deferred
+			$tempFile = TempFSFile::factory( 'create_', 'tmp' );
+			if ( !$tempFile ) {
+				$status->fatal( 'backend-fail-create', $params['dst'] );
 				return $status;
 			}
+			$this->trapWarnings();
+			$bytes = file_put_contents( $tempFile->getPath(), $params['content'] );
+			$this->untrapWarnings();
+			if ( $bytes === false ) {
+				$status->fatal( 'backend-fail-create', $params['dst'] );
+				return $status;
+			}
+			$cmd = implode( ' ', array(
+				wfIsWindows() ? 'COPY /B /Y' : 'cp', // (binary, overwrite)
+				wfEscapeShellArg( $this->cleanPathSlashes( $tempFile->getPath() ) ),
+				wfEscapeShellArg( $this->cleanPathSlashes( $dest ) )
+			) );
+			$status->value = new FSFileOpHandle( $this, $params, 'Create', $cmd, $dest );
+			$tempFile->bind( $status->value );
+		} else { // immediate write
+			$this->trapWarnings();
+			$bytes = file_put_contents( $dest, $params['content'] );
+			$this->untrapWarnings();
+			if ( $bytes === false ) {
+				$status->fatal( 'backend-fail-create', $params['dst'] );
+				return $status;
+			}
+			$this->chmod( $dest );
+		}
+
+		return $status;
+	}
+
+	/**
+	 * @see FSFileBackend::doExecuteOpHandlesInternal()
+	 */
+	protected function _getResponseCreate( $errors, Status $status, array $params, $cmd ) {
+		if ( $errors !== '' && !( wfIsWindows() && $errors[0] === " " ) ) {
+			$status->fatal( 'backend-fail-create', $params['dst'] );
+			trigger_error( "$cmd\n$errors", E_USER_WARNING ); // command output
+		}
+	}
+
+	protected function doStoreInternal( array $params ) {
+		$status = Status::newGood();
+
+		$dest = $this->resolveToFSPath( $params['dst'] );
+		if ( $dest === null ) {
+			$status->fatal( 'backend-fail-invalidpath', $params['dst'] );
+			return $status;
 		}
 
 		if ( !empty( $params['async'] ) ) { // deferred
-			$cmd = implode( ' ', array( wfIsWindows() ? 'COPY' : 'cp',
+			$cmd = implode( ' ', array(
+				wfIsWindows() ? 'COPY /B /Y' : 'cp', // (binary, overwrite)
 				wfEscapeShellArg( $this->cleanPathSlashes( $params['src'] ) ),
 				wfEscapeShellArg( $this->cleanPathSlashes( $dest ) )
 			) );
 			$status->value = new FSFileOpHandle( $this, $params, 'Store', $cmd, $dest );
 		} else { // immediate write
+			$this->trapWarnings();
 			$ok = copy( $params['src'], $dest );
+			$this->untrapWarnings();
 			// In some cases (at least over NFS), copy() returns true when it fails
 			if ( !$ok || ( filesize( $params['src'] ) !== filesize( $dest ) ) ) {
 				if ( $ok ) { // PHP bug
@@ -236,10 +266,6 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doCopyInternal()
-	 * @return Status
-	 */
 	protected function doCopyInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -255,31 +281,30 @@ class FSFileBackend extends FileBackendStore {
 			return $status;
 		}
 
-		if ( file_exists( $dest ) ) {
-			if ( !empty( $params['overwrite'] ) ) {
-				$ok = unlink( $dest );
-				if ( !$ok ) {
-					$status->fatal( 'backend-fail-delete', $params['dst'] );
-					return $status;
-				}
-			} else {
-				$status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
-				return $status;
+		if ( !is_file( $source ) ) {
+			if ( empty( $params['ignoreMissingSource'] ) ) {
+				$status->fatal( 'backend-fail-copy', $params['src'] );
 			}
+			return $status; // do nothing; either OK or bad status
 		}
 
 		if ( !empty( $params['async'] ) ) { // deferred
-			$cmd = implode( ' ', array( wfIsWindows() ? 'COPY' : 'cp',
+			$cmd = implode( ' ', array(
+				wfIsWindows() ? 'COPY /B /Y' : 'cp', // (binary, overwrite)
 				wfEscapeShellArg( $this->cleanPathSlashes( $source ) ),
 				wfEscapeShellArg( $this->cleanPathSlashes( $dest ) )
 			) );
 			$status->value = new FSFileOpHandle( $this, $params, 'Copy', $cmd, $dest );
 		} else { // immediate write
-			$ok = copy( $source, $dest );
+			$this->trapWarnings();
+			$ok = ( $source === $dest ) ? true : copy( $source, $dest );
+			$this->untrapWarnings();
 			// In some cases (at least over NFS), copy() returns true when it fails
 			if ( !$ok || ( filesize( $source ) !== filesize( $dest ) ) ) {
 				if ( $ok ) { // PHP bug
+					$this->trapWarnings();
 					unlink( $dest ); // remove broken file
+					$this->untrapWarnings();
 					trigger_error( __METHOD__ . ": copy() failed but returned true." );
 				}
 				$status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
@@ -301,10 +326,6 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doMoveInternal()
-	 * @return Status
-	 */
 	protected function doMoveInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -320,30 +341,24 @@ class FSFileBackend extends FileBackendStore {
 			return $status;
 		}
 
-		if ( file_exists( $dest ) ) {
-			if ( !empty( $params['overwrite'] ) ) {
-				// Windows does not support moving over existing files
-				if ( wfIsWindows() ) {
-					$ok = unlink( $dest );
-					if ( !$ok ) {
-						$status->fatal( 'backend-fail-delete', $params['dst'] );
-						return $status;
-					}
-				}
-			} else {
-				$status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
-				return $status;
+		if ( !is_file( $source ) ) {
+			if ( empty( $params['ignoreMissingSource'] ) ) {
+				$status->fatal( 'backend-fail-move', $params['src'] );
 			}
+			return $status; // do nothing; either OK or bad status
 		}
 
 		if ( !empty( $params['async'] ) ) { // deferred
-			$cmd = implode( ' ', array( wfIsWindows() ? 'MOVE' : 'mv',
+			$cmd = implode( ' ', array(
+				wfIsWindows() ? 'MOVE /Y' : 'mv', // (overwrite)
 				wfEscapeShellArg( $this->cleanPathSlashes( $source ) ),
 				wfEscapeShellArg( $this->cleanPathSlashes( $dest ) )
 			) );
 			$status->value = new FSFileOpHandle( $this, $params, 'Move', $cmd );
 		} else { // immediate write
-			$ok = rename( $source, $dest );
+			$this->trapWarnings();
+			$ok = ( $source === $dest ) ? true : rename( $source, $dest );
+			$this->untrapWarnings();
 			clearstatcache(); // file no longer at source
 			if ( !$ok ) {
 				$status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
@@ -364,10 +379,6 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doDeleteInternal()
-	 * @return Status
-	 */
 	protected function doDeleteInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -385,12 +396,15 @@ class FSFileBackend extends FileBackendStore {
 		}
 
 		if ( !empty( $params['async'] ) ) { // deferred
-			$cmd = implode( ' ', array( wfIsWindows() ? 'DEL' : 'unlink',
+			$cmd = implode( ' ', array(
+				wfIsWindows() ? 'DEL' : 'unlink',
 				wfEscapeShellArg( $this->cleanPathSlashes( $source ) )
 			) );
 			$status->value = new FSFileOpHandle( $this, $params, 'Copy', $cmd );
 		} else { // immediate write
+			$this->trapWarnings();
 			$ok = unlink( $source );
+			$this->untrapWarnings();
 			if ( !$ok ) {
 				$status->fatal( 'backend-fail-delete', $params['src'] );
 				return $status;
@@ -410,174 +424,96 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doCreateInternal()
-	 * @return Status
-	 */
-	protected function doCreateInternal( array $params ) {
-		$status = Status::newGood();
-
-		$dest = $this->resolveToFSPath( $params['dst'] );
-		if ( $dest === null ) {
-			$status->fatal( 'backend-fail-invalidpath', $params['dst'] );
-			return $status;
-		}
-
-		if ( file_exists( $dest ) ) {
-			if ( !empty( $params['overwrite'] ) ) {
-				$ok = unlink( $dest );
-				if ( !$ok ) {
-					$status->fatal( 'backend-fail-delete', $params['dst'] );
-					return $status;
-				}
-			} else {
-				$status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
-				return $status;
-			}
-		}
-
-		if ( !empty( $params['async'] ) ) { // deferred
-			$tempFile = TempFSFile::factory( 'create_', 'tmp' );
-			if ( !$tempFile ) {
-				$status->fatal( 'backend-fail-create', $params['dst'] );
-				return $status;
-			}
-			$bytes = file_put_contents( $tempFile->getPath(), $params['content'] );
-			if ( $bytes === false ) {
-				$status->fatal( 'backend-fail-create', $params['dst'] );
-				return $status;
-			}
-			$cmd = implode( ' ', array( wfIsWindows() ? 'COPY' : 'cp',
-				wfEscapeShellArg( $this->cleanPathSlashes( $tempFile->getPath() ) ),
-				wfEscapeShellArg( $this->cleanPathSlashes( $dest ) )
-			) );
-			$status->value = new FSFileOpHandle( $this, $params, 'Create', $cmd, $dest );
-			$tempFile->bind( $status->value );
-		} else { // immediate write
-			$bytes = file_put_contents( $dest, $params['content'] );
-			if ( $bytes === false ) {
-				$status->fatal( 'backend-fail-create', $params['dst'] );
-				return $status;
-			}
-			$this->chmod( $dest );
-		}
-
-		return $status;
-	}
-
-	/**
-	 * @see FSFileBackend::doExecuteOpHandlesInternal()
-	 */
-	protected function _getResponseCreate( $errors, Status $status, array $params, $cmd ) {
-		if ( $errors !== '' && !( wfIsWindows() && $errors[0] === " " ) ) {
-			$status->fatal( 'backend-fail-create', $params['dst'] );
-			trigger_error( "$cmd\n$errors", E_USER_WARNING ); // command output
-		}
-	}
-
-	/**
-	 * @see FileBackendStore::doPrepareInternal()
-	 * @return Status
-	 */
 	protected function doPrepareInternal( $fullCont, $dirRel, array $params ) {
 		$status = Status::newGood();
-		list( $b, $shortCont, $r ) = FileBackend::splitStoragePath( $params['dir'] );
+		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
 		$contRoot = $this->containerFSRoot( $shortCont, $fullCont ); // must be valid
 		$dir = ( $dirRel != '' ) ? "{$contRoot}/{$dirRel}" : $contRoot;
 		$existed = is_dir( $dir ); // already there?
-		if ( !wfMkdirParents( $dir ) ) { // make directory and its parents
+		// Create the directory and its parents as needed...
+		$this->trapWarnings();
+		if ( !wfMkdirParents( $dir ) ) {
 			$status->fatal( 'directorycreateerror', $params['dir'] ); // fails on races
 		} elseif ( !is_writable( $dir ) ) {
 			$status->fatal( 'directoryreadonlyerror', $params['dir'] );
 		} elseif ( !is_readable( $dir ) ) {
 			$status->fatal( 'directorynotreadableerror', $params['dir'] );
 		}
+		$this->untrapWarnings();
+		// Respect any 'noAccess' or 'noListing' flags...
 		if ( is_dir( $dir ) && !$existed ) {
-			// Respect any 'noAccess' or 'noListing' flags...
 			$status->merge( $this->doSecureInternal( $fullCont, $dirRel, $params ) );
 		}
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doSecureInternal()
-	 * @return Status
-	 */
 	protected function doSecureInternal( $fullCont, $dirRel, array $params ) {
 		$status = Status::newGood();
-		list( $b, $shortCont, $r ) = FileBackend::splitStoragePath( $params['dir'] );
+		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
 		$contRoot = $this->containerFSRoot( $shortCont, $fullCont ); // must be valid
 		$dir = ( $dirRel != '' ) ? "{$contRoot}/{$dirRel}" : $contRoot;
 		// Seed new directories with a blank index.html, to prevent crawling...
 		if ( !empty( $params['noListing'] ) && !file_exists( "{$dir}/index.html" ) ) {
+			$this->trapWarnings();
 			$bytes = file_put_contents( "{$dir}/index.html", $this->indexHtmlPrivate() );
+			$this->untrapWarnings();
 			if ( $bytes === false ) {
 				$status->fatal( 'backend-fail-create', $params['dir'] . '/index.html' );
-				return $status;
 			}
 		}
 		// Add a .htaccess file to the root of the container...
 		if ( !empty( $params['noAccess'] ) && !file_exists( "{$contRoot}/.htaccess" ) ) {
+			$this->trapWarnings();
 			$bytes = file_put_contents( "{$contRoot}/.htaccess", $this->htaccessPrivate() );
+			$this->untrapWarnings();
 			if ( $bytes === false ) {
 				$storeDir = "mwstore://{$this->name}/{$shortCont}";
 				$status->fatal( 'backend-fail-create', "{$storeDir}/.htaccess" );
-				return $status;
 			}
 		}
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doPublishInternal()
-	 * @return Status
-	 */
 	protected function doPublishInternal( $fullCont, $dirRel, array $params ) {
 		$status = Status::newGood();
-		list( $b, $shortCont, $r ) = FileBackend::splitStoragePath( $params['dir'] );
+		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
 		$contRoot = $this->containerFSRoot( $shortCont, $fullCont ); // must be valid
 		$dir = ( $dirRel != '' ) ? "{$contRoot}/{$dirRel}" : $contRoot;
 		// Unseed new directories with a blank index.html, to allow crawling...
 		if ( !empty( $params['listing'] ) && is_file( "{$dir}/index.html" ) ) {
 			$exists = ( file_get_contents( "{$dir}/index.html" ) === $this->indexHtmlPrivate() );
+			$this->trapWarnings();
 			if ( $exists && !unlink( "{$dir}/index.html" ) ) { // reverse secure()
 				$status->fatal( 'backend-fail-delete', $params['dir'] . '/index.html' );
-				return $status;
 			}
+			$this->untrapWarnings();
 		}
 		// Remove the .htaccess file from the root of the container...
 		if ( !empty( $params['access'] ) && is_file( "{$contRoot}/.htaccess" ) ) {
 			$exists = ( file_get_contents( "{$contRoot}/.htaccess" ) === $this->htaccessPrivate() );
+			$this->trapWarnings();
 			if ( $exists && !unlink( "{$contRoot}/.htaccess" ) ) { // reverse secure()
 				$storeDir = "mwstore://{$this->name}/{$shortCont}";
 				$status->fatal( 'backend-fail-delete', "{$storeDir}/.htaccess" );
-				return $status;
 			}
+			$this->untrapWarnings();
 		}
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doCleanInternal()
-	 * @return Status
-	 */
 	protected function doCleanInternal( $fullCont, $dirRel, array $params ) {
 		$status = Status::newGood();
-		list( $b, $shortCont, $r ) = FileBackend::splitStoragePath( $params['dir'] );
+		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
 		$contRoot = $this->containerFSRoot( $shortCont, $fullCont ); // must be valid
 		$dir = ( $dirRel != '' ) ? "{$contRoot}/{$dirRel}" : $contRoot;
-		wfSuppressWarnings();
+		$this->trapWarnings();
 		if ( is_dir( $dir ) ) {
 			rmdir( $dir ); // remove directory if empty
 		}
-		wfRestoreWarnings();
+		$this->untrapWarnings();
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doFileExists()
-	 * @return array|bool|null
-	 */
 	protected function doGetFileStat( array $params ) {
 		$source = $this->resolveToFSPath( $params['src'] );
 		if ( $source === null ) {
@@ -591,7 +527,7 @@ class FSFileBackend extends FileBackendStore {
 		if ( $stat ) {
 			return array(
 				'mtime' => wfTimestamp( TS_MW, $stat['mtime'] ),
-				'size'  => $stat['size']
+				'size' => $stat['size']
 			);
 		} elseif ( !$hadError ) {
 			return false; // file does not exist
@@ -607,12 +543,8 @@ class FSFileBackend extends FileBackendStore {
 		clearstatcache(); // clear the PHP file stat cache
 	}
 
-	/**
-	 * @see FileBackendStore::doDirectoryExists()
-	 * @return bool|null
-	 */
 	protected function doDirectoryExists( $fullCont, $dirRel, array $params ) {
-		list( $b, $shortCont, $r ) = FileBackend::splitStoragePath( $params['dir'] );
+		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
 		$contRoot = $this->containerFSRoot( $shortCont, $fullCont ); // must be valid
 		$dir = ( $dirRel != '' ) ? "{$contRoot}/{$dirRel}" : $contRoot;
 
@@ -628,7 +560,7 @@ class FSFileBackend extends FileBackendStore {
 	 * @return Array|null
 	 */
 	public function getDirectoryListInternal( $fullCont, $dirRel, array $params ) {
-		list( $b, $shortCont, $r ) = FileBackend::splitStoragePath( $params['dir'] );
+		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
 		$contRoot = $this->containerFSRoot( $shortCont, $fullCont ); // must be valid
 		$dir = ( $dirRel != '' ) ? "{$contRoot}/{$dirRel}" : $contRoot;
 		$exists = is_dir( $dir );
@@ -644,10 +576,10 @@ class FSFileBackend extends FileBackendStore {
 
 	/**
 	 * @see FileBackendStore::getFileListInternal()
-	 * @return array|FSFileBackendFileList|null
+	 * @return Array|FSFileBackendFileList|null
 	 */
 	public function getFileListInternal( $fullCont, $dirRel, array $params ) {
-		list( $b, $shortCont, $r ) = FileBackend::splitStoragePath( $params['dir'] );
+		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
 		$contRoot = $this->containerFSRoot( $shortCont, $fullCont ); // must be valid
 		$dir = ( $dirRel != '' ) ? "{$contRoot}/{$dirRel}" : $contRoot;
 		$exists = is_dir( $dir );
@@ -661,59 +593,57 @@ class FSFileBackend extends FileBackendStore {
 		return new FSFileBackendFileList( $dir, $params );
 	}
 
-	/**
-	 * @see FileBackendStore::getLocalReference()
-	 * @return FSFile|null
-	 */
-	public function getLocalReference( array $params ) {
-		$source = $this->resolveToFSPath( $params['src'] );
-		if ( $source === null ) {
-			return null;
-		}
-		return new FSFile( $source );
-	}
+	protected function doGetLocalReferenceMulti( array $params ) {
+		$fsFiles = array(); // (path => FSFile)
 
-	/**
-	 * @see FileBackendStore::getLocalCopy()
-	 * @return null|TempFSFile
-	 */
-	public function getLocalCopy( array $params ) {
-		$source = $this->resolveToFSPath( $params['src'] );
-		if ( $source === null ) {
-			return null;
+		foreach ( $params['srcs'] as $src ) {
+			$source = $this->resolveToFSPath( $src );
+			if ( $source === null || !is_file( $source ) ) {
+				$fsFiles[$src] = null; // invalid path or file does not exist
+			} else {
+				$fsFiles[$src] = new FSFile( $source );
+			}
 		}
 
-		// Create a new temporary file with the same extension...
-		$ext = FileBackend::extensionFromPath( $params['src'] );
-		$tmpFile = TempFSFile::factory( 'localcopy_', $ext );
-		if ( !$tmpFile ) {
-			return null;
-		}
-		$tmpPath = $tmpFile->getPath();
+		return $fsFiles;
+	}
 
-		// Copy the source file over the temp file
-		$ok = copy( $source, $tmpPath );
-		if ( !$ok ) {
-			return null;
-		}
+	protected function doGetLocalCopyMulti( array $params ) {
+		$tmpFiles = array(); // (path => TempFSFile)
 
-		$this->chmod( $tmpPath );
+		foreach ( $params['srcs'] as $src ) {
+			$source = $this->resolveToFSPath( $src );
+			if ( $source === null ) {
+				$tmpFiles[$src] = null; // invalid path
+			} else {
+				// Create a new temporary file with the same extension...
+				$ext = FileBackend::extensionFromPath( $src );
+				$tmpFile = TempFSFile::factory( 'localcopy_', $ext );
+				if ( !$tmpFile ) {
+					$tmpFiles[$src] = null;
+				} else {
+					$tmpPath = $tmpFile->getPath();
+					// Copy the source file over the temp file
+					$this->trapWarnings();
+					$ok = copy( $source, $tmpPath );
+					$this->untrapWarnings();
+					if ( !$ok ) {
+						$tmpFiles[$src] = null;
+					} else {
+						$this->chmod( $tmpPath );
+						$tmpFiles[$src] = $tmpFile;
+					}
+				}
+			}
+		}
 
-		return $tmpFile;
+		return $tmpFiles;
 	}
 
-	/**
-	 * @see FileBackendStore::directoriesAreVirtual()
-	 * @return bool
-	 */
 	protected function directoriesAreVirtual() {
 		return false;
 	}
 
-	/**
-	 * @see FileBackendStore::doExecuteOpHandlesInternal()
-	 * @return Array List of corresponding Status objects
-	 */
 	protected function doExecuteOpHandlesInternal( array $fileOpHandles ) {
 		$statuses = array();
 
@@ -747,13 +677,13 @@ class FSFileBackend extends FileBackendStore {
 	/**
 	 * Chmod a file, suppressing the warnings
 	 *
-	 * @param $path string Absolute file system path
+	 * @param string $path Absolute file system path
 	 * @return bool Success
 	 */
 	protected function chmod( $path ) {
-		wfSuppressWarnings();
+		$this->trapWarnings();
 		$ok = chmod( $path, $this->fileMode );
-		wfRestoreWarnings();
+		$this->untrapWarnings();
 
 		return $ok;
 	}
@@ -779,7 +709,7 @@ class FSFileBackend extends FileBackendStore {
 	/**
 	 * Clean up directory separators for the given OS
 	 *
-	 * @param $path string FS path
+	 * @param string $path FS path
 	 * @return string
 	 */
 	protected function cleanPathSlashes( $path ) {
@@ -789,12 +719,11 @@ class FSFileBackend extends FileBackendStore {
 	/**
 	 * Listen for E_WARNING errors and track whether any happen
 	 *
-	 * @return bool
+	 * @return void
 	 */
 	protected function trapWarnings() {
 		$this->hadWarningErrors[] = false; // push to stack
 		set_error_handler( array( $this, 'handleWarning' ), E_WARNING );
-		return false; // invoke normal PHP error handler
 	}
 
 	/**
@@ -808,9 +737,13 @@ class FSFileBackend extends FileBackendStore {
 	}
 
 	/**
+	 * @param integer $errno
+	 * @param string $errstr
 	 * @return bool
+	 * @access private
 	 */
-	private function handleWarning() {
+	public function handleWarning( $errno, $errstr ) {
+		wfDebugLog( 'FSFileBackend', $errstr ); // more detailed error logging
 		$this->hadWarningErrors[count( $this->hadWarningErrors ) - 1] = true;
 		return true; // suppress from PHP handler
 	}
@@ -824,13 +757,15 @@ class FSFileOpHandle extends FileBackendStoreOpHandle {
 	public $chmodPath; // string; file to chmod
 
 	/**
-	 * @param $backend
-	 * @param $params array
-	 * @param $call
-	 * @param $cmd
-	 * @param $chmodPath null
+	 * @param FSFileBackend $backend
+	 * @param array $params
+	 * @param string $call
+	 * @param string $cmd
+	 * @param integer|null $chmodPath
 	 */
-	public function __construct( $backend, array $params, $call, $cmd, $chmodPath = null ) {
+	public function __construct(
+		FSFileBackend $backend, array $params, $call, $cmd, $chmodPath = null
+	) {
 		$this->backend = $backend;
 		$this->params = $params;
 		$this->call = $call;
@@ -855,16 +790,19 @@ abstract class FSFileBackendList implements Iterator {
 	protected $params = array();
 
 	/**
-	 * @param $dir string file system directory
-	 * @param $params array
+	 * @param string $dir file system directory
+	 * @param array $params
 	 */
 	public function __construct( $dir, array $params ) {
-		$dir = realpath( $dir ); // normalize
-		$this->suffixStart = strlen( $dir ) + 1; // size of "path/to/dir/"
+		$path = realpath( $dir ); // normalize
+		if ( $path === false ) {
+			$path = $dir;
+		}
+		$this->suffixStart = strlen( $path ) + 1; // size of "path/to/dir/"
 		$this->params = $params;
 
 		try {
-			$this->iter = $this->initIterator( $dir );
+			$this->iter = $this->initIterator( $path );
 		} catch ( UnexpectedValueException $e ) {
 			$this->iter = null; // bad permissions? deleted?
 		}
@@ -873,7 +811,7 @@ abstract class FSFileBackendList implements Iterator {
 	/**
 	 * Return an appropriate iterator object to wrap
 	 *
-	 * @param $dir string file system directory
+	 * @param string $dir file system directory
 	 * @return Iterator
 	 */
 	protected function initIterator( $dir ) {
@@ -916,8 +854,8 @@ abstract class FSFileBackendList implements Iterator {
 		try {
 			$this->iter->next();
 			$this->filterViaNext();
-		} catch ( UnexpectedValueException $e ) {
-			$this->iter = null;
+		} catch ( UnexpectedValueException $e ) { // bad permissions? deleted?
+			throw new FileBackendError( "File iterator gave UnexpectedValueException." );
 		}
 		++$this->pos;
 	}
@@ -931,8 +869,8 @@ abstract class FSFileBackendList implements Iterator {
 		try {
 			$this->iter->rewind();
 			$this->filterViaNext();
-		} catch ( UnexpectedValueException $e ) {
-			$this->iter = null;
+		} catch ( UnexpectedValueException $e ) { // bad permissions? deleted?
+			throw new FileBackendError( "File iterator gave UnexpectedValueException." );
 		}
 	}
 
@@ -953,11 +891,15 @@ abstract class FSFileBackendList implements Iterator {
 	 * Return only the relative path and normalize slashes to FileBackend-style.
 	 * Uses the "real path" since the suffix is based upon that.
 	 *
-	 * @param $path string
+	 * @param string $path
 	 * @return string
 	 */
-	protected function getRelPath( $path ) {
-		return strtr( substr( realpath( $path ), $this->suffixStart ), '\\', '/' );
+	protected function getRelPath( $dir ) {
+		$path = realpath( $dir );
+		if ( $path === false ) {
+			$path = $dir;
+		}
+		return strtr( substr( $path, $this->suffixStart ), '\\', '/' );
 	}
 }
 
diff --git a/includes/filebackend/FileBackend.php b/includes/filebackend/FileBackend.php
index 76c761b0..f586578b 100644
--- a/includes/filebackend/FileBackend.php
+++ b/includes/filebackend/FileBackend.php
@@ -1,7 +1,6 @@
 <?php
 /**
  * @defgroup FileBackend File backend
- * @ingroup  FileRepo
  *
  * File backend is used to interact with file storage systems,
  * such as the local file system, NFS, or cloud storage systems.
@@ -37,14 +36,18 @@
  * Outside callers can assume that all backends will have these functions.
  *
  * All "storage paths" are of the format "mwstore://<backend>/<container>/<path>".
- * The "<path>" portion is a relative path that uses UNIX file system (FS)
- * notation, though any particular backend may not actually be using a local
- * filesystem. Therefore, the relative paths are only virtual.
+ * The "backend" portion is unique name for MediaWiki to refer to a backend, while
+ * the "container" portion is a top-level directory of the backend. The "path" portion
+ * is a relative path that uses UNIX file system (FS) notation, though any particular
+ * backend may not actually be using a local filesystem. Therefore, the relative paths
+ * are only virtual.
  *
  * Backend contents are stored under wiki-specific container names by default.
- * For legacy reasons, this has no effect for the FS backend class, and per-wiki
- * segregation must be done by setting the container paths appropriately.
+ * Global (qualified) backends are achieved by configuring the "wiki ID" to a constant.
+ * For legacy reasons, the FSFileBackend class allows manually setting the paths of
+ * containers to ones that do not respect the "wiki ID".
  *
+ * In key/value stores, the container is the only hierarchy (the rest is emulated).
  * FS-based backends are somewhat more restrictive due to the existence of real
  * directory files; a regular file cannot have the same name as a directory. Other
  * backends with virtual directories may not have this limitation. Callers should
@@ -75,9 +78,13 @@ abstract class FileBackend {
 	 * $config includes:
 	 *   - name        : The unique name of this backend.
 	 *                   This should consist of alphanumberic, '-', and '_' characters.
-	 *                   This name should not be changed after use.
-	 *   - wikiId      : Prefix to container names that is unique to this wiki.
+	 *                   This name should not be changed after use (e.g. with journaling).
+	 *                   Note that the name is *not* used in actual container names.
+	 *   - wikiId      : Prefix to container names that is unique to this backend.
+	 *                   If not provided, this defaults to the current wiki ID.
 	 *                   It should only consist of alphanumberic, '-', and '_' characters.
+	 *                   This ID is what avoids collisions if multiple logical backends
+	 *                   use the same storage system, so this should be set carefully.
 	 *   - lockManager : Registered name of a file lock manager to use.
 	 *   - fileJournal : File journal configuration; see FileJournal::factory().
 	 *                   Journals simply log changes to files stored in the backend.
@@ -87,7 +94,7 @@ abstract class FileBackend {
 	 *                   Allowed values are "implicit", "explicit" and "off".
 	 *   - concurrency : How many file operations can be done in parallel.
 	 *
-	 * @param $config Array
+	 * @param array $config
 	 * @throws MWException
 	 */
 	public function __construct( array $config ) {
@@ -100,7 +107,7 @@ abstract class FileBackend {
 			: wfWikiID(); // e.g. "my_wiki-en_"
 		$this->lockManager = ( $config['lockManager'] instanceof LockManager )
 			? $config['lockManager']
-			: LockManagerGroup::singleton()->get( $config['lockManager'] );
+			: LockManagerGroup::singleton( $this->wikiId )->get( $config['lockManager'] );
 		$this->fileJournal = isset( $config['fileJournal'] )
 			? ( ( $config['fileJournal'] instanceof FileJournal )
 				? $config['fileJournal']
@@ -129,7 +136,8 @@ abstract class FileBackend {
 	}
 
 	/**
-	 * Get the wiki identifier used for this backend (possibly empty)
+	 * Get the wiki identifier used for this backend (possibly empty).
+	 * Note that this might *not* be in the same format as wfWikiID().
 	 *
 	 * @return string
 	 * @since 1.20
@@ -171,6 +179,7 @@ abstract class FileBackend {
 	 *  - copy
 	 *  - move
 	 *  - delete
+	 *  - describe (since 1.21)
 	 *  - null
 	 *
 	 * a) Create a new file in storage with the contents of a string
@@ -181,7 +190,7 @@ abstract class FileBackend {
 	 *         'content'             => <string of new file contents>,
 	 *         'overwrite'           => <boolean>,
 	 *         'overwriteSame'       => <boolean>,
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     );
 	 * @endcode
 	 *
@@ -193,7 +202,7 @@ abstract class FileBackend {
 	 *         'dst'                 => <storage path>,
 	 *         'overwrite'           => <boolean>,
 	 *         'overwriteSame'       => <boolean>,
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
 	 *
@@ -205,7 +214,8 @@ abstract class FileBackend {
 	 *         'dst'                 => <storage path>,
 	 *         'overwrite'           => <boolean>,
 	 *         'overwriteSame'       => <boolean>,
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'ignoreMissingSource' => <boolean>, # since 1.21
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
 	 *
@@ -217,7 +227,8 @@ abstract class FileBackend {
 	 *         'dst'                 => <storage path>,
 	 *         'overwrite'           => <boolean>,
 	 *         'overwriteSame'       => <boolean>,
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'ignoreMissingSource' => <boolean>, # since 1.21
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
 	 *
@@ -230,7 +241,16 @@ abstract class FileBackend {
 	 *     )
 	 * @endcode
 	 *
-	 * f) Do nothing (no-op)
+	 * f) Update metadata for a file within storage
+	 * @code
+	 *     array(
+	 *         'op'                  => 'describe',
+	 *         'src'                 => <storage path>,
+	 *         'headers'             => <HTTP header name/value map>
+	 *     )
+	 * @endcode
+	 *
+	 * g) Do nothing (no-op)
 	 * @code
 	 *     array(
 	 *         'op'                  => 'null',
@@ -241,31 +261,35 @@ abstract class FileBackend {
 	 *   - ignoreMissingSource : The operation will simply succeed and do
 	 *                           nothing if the source file does not exist.
 	 *   - overwrite           : Any destination file will be overwritten.
-	 *   - overwriteSame       : An error will not be given if a file already
-	 *                           exists at the destination that has the same
-	 *                           contents as the new contents to be written there.
-	 *   - disposition         : When supplied, the backend will add a Content-Disposition
-	 *                           header when GETs/HEADs of the destination file are made.
-	 *                           Backends that don't support file metadata will ignore this.
-	 *                           See http://tools.ietf.org/html/rfc6266 (since 1.20).
+	 *   - overwriteSame       : If a file already exists at the destination with the
+	 *                           same contents, then do nothing to the destination file
+	 *                           instead of giving an error. This does not compare headers.
+	 *                           This option is ignored if 'overwrite' is already provided.
+	 *   - headers             : If supplied, the result of merging these headers with any
+	 *                           existing source file headers (replacing conflicting ones)
+	 *                           will be set as the destination file headers. Headers are
+	 *                           deleted if their value is set to the empty string. When a
+	 *                           file has headers they are included in responses to GET and
+	 *                           HEAD requests to the backing store for that file.
+	 *                           Header values should be no larger than 255 bytes, except for
+	 *                           Content-Disposition. The system might ignore or truncate any
+	 *                           headers that are too long to store (exact limits will vary).
+	 *                           Backends that don't support metadata ignore this. (since 1.21)
 	 *
 	 * $opts is an associative of boolean flags, including:
 	 *   - force               : Operation precondition errors no longer trigger an abort.
 	 *                           Any remaining operations are still attempted. Unexpected
-	 *                           failures may still cause remaning operations to be aborted.
+	 *                           failures may still cause remaining operations to be aborted.
 	 *   - nonLocking          : No locks are acquired for the operations.
 	 *                           This can increase performance for non-critical writes.
 	 *                           This has no effect unless the 'force' flag is set.
-	 *   - allowStale          : Don't require the latest available data.
-	 *                           This can increase performance for non-critical writes.
-	 *                           This has no effect unless the 'force' flag is set.
 	 *   - nonJournaled        : Don't log this operation batch in the file journal.
 	 *                           This limits the ability of recovery scripts.
 	 *   - parallelize         : Try to do operations in parallel when possible.
-	 *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20).
+	 *   - bypassReadOnly      : Allow writes in read-only mode. (since 1.20)
 	 *   - preserveCache       : Don't clear the process cache before checking files.
 	 *                           This should only be used if all entries in the process
-	 *                           cache were added after the files were already locked (since 1.20).
+	 *                           cache were added after the files were already locked. (since 1.20)
 	 *
 	 * @remarks Remarks on locking:
 	 * File system paths given to operations should refer to files that are
@@ -282,28 +306,26 @@ abstract class FileBackend {
 	 *   - a) unexpected operation errors occurred (network partitions, disk full...)
 	 *   - b) significant operation errors occurred and 'force' was not set
 	 *
-	 * @param $ops Array List of operations to execute in order
-	 * @param $opts Array Batch operation options
+	 * @param array $ops List of operations to execute in order
+	 * @param array $opts Batch operation options
 	 * @return Status
 	 */
 	final public function doOperations( array $ops, array $opts = array() ) {
 		if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 			return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 		}
+		if ( !count( $ops ) ) {
+			return Status::newGood(); // nothing to do
+		}
 		if ( empty( $opts['force'] ) ) { // sanity
 			unset( $opts['nonLocking'] );
-			unset( $opts['allowStale'] );
 		}
-		$opts['concurrency'] = 1; // off
-		if ( $this->parallelize === 'implicit' ) {
-			if ( !isset( $opts['parallelize'] ) || $opts['parallelize'] ) {
-				$opts['concurrency'] = $this->concurrency;
-			}
-		} elseif ( $this->parallelize === 'explicit' ) {
-			if ( !empty( $opts['parallelize'] ) ) {
-				$opts['concurrency'] = $this->concurrency;
+		foreach ( $ops as &$op ) {
+			if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
+				$op['headers']['Content-Disposition'] = $op['disposition'];
 			}
 		}
+		$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 		return $this->doOperationsInternal( $ops, $opts );
 	}
 
@@ -319,8 +341,8 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doOperations()
 	 *
-	 * @param $op Array Operation
-	 * @param $opts Array Operation options
+	 * @param array $op Operation
+	 * @param array $opts Operation options
 	 * @return Status
 	 */
 	final public function doOperation( array $op, array $opts = array() ) {
@@ -333,8 +355,8 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doOperation()
 	 *
-	 * @param $params Array Operation parameters
-	 * @param $opts Array Operation options
+	 * @param array $params Operation parameters
+	 * @param array $opts Operation options
 	 * @return Status
 	 */
 	final public function create( array $params, array $opts = array() ) {
@@ -347,8 +369,8 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doOperation()
 	 *
-	 * @param $params Array Operation parameters
-	 * @param $opts Array Operation options
+	 * @param array $params Operation parameters
+	 * @param array $opts Operation options
 	 * @return Status
 	 */
 	final public function store( array $params, array $opts = array() ) {
@@ -361,8 +383,8 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doOperation()
 	 *
-	 * @param $params Array Operation parameters
-	 * @param $opts Array Operation options
+	 * @param array $params Operation parameters
+	 * @param array $opts Operation options
 	 * @return Status
 	 */
 	final public function copy( array $params, array $opts = array() ) {
@@ -375,8 +397,8 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doOperation()
 	 *
-	 * @param $params Array Operation parameters
-	 * @param $opts Array Operation options
+	 * @param array $params Operation parameters
+	 * @param array $opts Operation options
 	 * @return Status
 	 */
 	final public function move( array $params, array $opts = array() ) {
@@ -389,8 +411,8 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doOperation()
 	 *
-	 * @param $params Array Operation parameters
-	 * @param $opts Array Operation options
+	 * @param array $params Operation parameters
+	 * @param array $opts Operation options
 	 * @return Status
 	 */
 	final public function delete( array $params, array $opts = array() ) {
@@ -398,6 +420,21 @@ abstract class FileBackend {
 	}
 
 	/**
+	 * Performs a single describe operation.
+	 * This sets $params['op'] to 'describe' and passes it to doOperation().
+	 *
+	 * @see FileBackend::doOperation()
+	 *
+	 * @param array $params Operation parameters
+	 * @param array $opts Operation options
+	 * @return Status
+	 * @since 1.21
+	 */
+	final public function describe( array $params, array $opts = array() ) {
+		return $this->doOperation( array( 'op' => 'describe' ) + $params, $opts );
+	}
+
+	/**
 	 * Perform a set of independent file operations on some files.
 	 *
 	 * This does no locking, nor journaling, and possibly no stat calls.
@@ -410,6 +447,7 @@ abstract class FileBackend {
 	 *  - copy
 	 *  - move
 	 *  - delete
+	 *  - describe (since 1.21)
 	 *  - null
 	 *
 	 * a) Create a new file in storage with the contents of a string
@@ -418,36 +456,42 @@ abstract class FileBackend {
 	 *         'op'                  => 'create',
 	 *         'dst'                 => <storage path>,
 	 *         'content'             => <string of new file contents>,
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
+	 *
 	 * b) Copy a file system file into storage
 	 * @code
 	 *     array(
 	 *         'op'                  => 'store',
 	 *         'src'                 => <file system path>,
 	 *         'dst'                 => <storage path>,
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
+	 *
 	 * c) Copy a file within storage
 	 * @code
 	 *     array(
 	 *         'op'                  => 'copy',
 	 *         'src'                 => <storage path>,
 	 *         'dst'                 => <storage path>,
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'ignoreMissingSource' => <boolean>, # since 1.21
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
+	 *
 	 * d) Move a file within storage
 	 * @code
 	 *     array(
 	 *         'op'                  => 'move',
 	 *         'src'                 => <storage path>,
 	 *         'dst'                 => <storage path>,
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'ignoreMissingSource' => <boolean>, # since 1.21
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
+	 *
 	 * e) Delete a file within storage
 	 * @code
 	 *     array(
@@ -456,7 +500,17 @@ abstract class FileBackend {
 	 *         'ignoreMissingSource' => <boolean>
 	 *     )
 	 * @endcode
-	 * f) Do nothing (no-op)
+	 *
+	 * f) Update metadata for a file within storage
+	 * @code
+	 *     array(
+	 *         'op'                  => 'describe',
+	 *         'src'                 => <storage path>,
+	 *         'headers'             => <HTTP header name/value map>
+	 *     )
+	 * @endcode
+	 *
+	 * g) Do nothing (no-op)
 	 * @code
 	 *     array(
 	 *         'op'                  => 'null',
@@ -466,10 +520,15 @@ abstract class FileBackend {
 	 * @par Boolean flags for operations (operation-specific):
 	 *   - ignoreMissingSource : The operation will simply succeed and do
 	 *                           nothing if the source file does not exist.
-	 *   - disposition         : When supplied, the backend will add a Content-Disposition
-	 *                           header when GETs/HEADs of the destination file are made.
-	 *                           Backends that don't support file metadata will ignore this.
-	 *                           See http://tools.ietf.org/html/rfc6266 (since 1.20).
+	 *   - headers             : If supplied with a header name/value map, the backend will
+	 *                           reply with these headers when GETs/HEADs of the destination
+	 *                           file are made. Header values should be smaller than 256 bytes.
+	 *                           Content-Disposition headers can be longer, though the system
+	 *                           might ignore or truncate ones that are too long to store.
+	 *                           Existing headers will remain, but these will replace any
+	 *                           conflicting previous headers, and headers will be removed
+	 *                           if they are set to an empty string.
+	 *                           Backends that don't support metadata ignore this. (since 1.21)
 	 *
 	 * $opts is an associative of boolean flags, including:
 	 *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20)
@@ -480,8 +539,8 @@ abstract class FileBackend {
 	 * will reflect each operation attempted for the given files. The status will be
 	 * considered "OK" as long as no fatal errors occurred.
 	 *
-	 * @param $ops Array Set of operations to execute
-	 * @param $opts Array Batch operation options
+	 * @param array $ops Set of operations to execute
+	 * @param array $opts Batch operation options
 	 * @return Status
 	 * @since 1.20
 	 */
@@ -489,9 +548,16 @@ abstract class FileBackend {
 		if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 			return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 		}
+		if ( !count( $ops ) ) {
+			return Status::newGood(); // nothing to do
+		}
 		foreach ( $ops as &$op ) {
 			$op['overwrite'] = true; // avoids RTTs in key/value stores
+			if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
+				$op['headers']['Content-Disposition'] = $op['disposition'];
+			}
 		}
+		$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 		return $this->doQuickOperationsInternal( $ops );
 	}
 
@@ -507,7 +573,7 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doQuickOperations()
 	 *
-	 * @param $op Array Operation
+	 * @param array $op Operation
 	 * @return Status
 	 * @since 1.20
 	 */
@@ -521,7 +587,7 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doQuickOperation()
 	 *
-	 * @param $params Array Operation parameters
+	 * @param array $params Operation parameters
 	 * @return Status
 	 * @since 1.20
 	 */
@@ -535,7 +601,7 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doQuickOperation()
 	 *
-	 * @param $params Array Operation parameters
+	 * @param array $params Operation parameters
 	 * @return Status
 	 * @since 1.20
 	 */
@@ -549,7 +615,7 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doQuickOperation()
 	 *
-	 * @param $params Array Operation parameters
+	 * @param array $params Operation parameters
 	 * @return Status
 	 * @since 1.20
 	 */
@@ -563,7 +629,7 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doQuickOperation()
 	 *
-	 * @param $params Array Operation parameters
+	 * @param array $params Operation parameters
 	 * @return Status
 	 * @since 1.20
 	 */
@@ -577,7 +643,7 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doQuickOperation()
 	 *
-	 * @param $params Array Operation parameters
+	 * @param array $params Operation parameters
 	 * @return Status
 	 * @since 1.20
 	 */
@@ -586,15 +652,30 @@ abstract class FileBackend {
 	}
 
 	/**
+	 * Performs a single quick describe operation.
+	 * This sets $params['op'] to 'describe' and passes it to doQuickOperation().
+	 *
+	 * @see FileBackend::doQuickOperation()
+	 *
+	 * @param array $params Operation parameters
+	 * @return Status
+	 * @since 1.21
+	 */
+	final public function quickDescribe( array $params ) {
+		return $this->doQuickOperation( array( 'op' => 'describe' ) + $params );
+	}
+
+	/**
 	 * Concatenate a list of storage files into a single file system file.
 	 * The target path should refer to a file that is already locked or
 	 * otherwise safe from modification from other processes. Normally,
 	 * the file will be a new temp file, which should be adequate.
 	 *
-	 * @param $params Array Operation parameters
+	 * @param array $params Operation parameters
 	 * $params include:
-	 *   - srcs : ordered source storage paths (e.g. chunk1, chunk2, ...)
-	 *   - dst  : file system path to 0-byte temp file
+	 *   - srcs        : ordered source storage paths (e.g. chunk1, chunk2, ...)
+	 *   - dst         : file system path to 0-byte temp file
+	 *   - parallelize : try to do operations in parallel when possible
 	 * @return Status
 	 */
 	abstract public function concatenate( array $params );
@@ -607,8 +688,10 @@ abstract class FileBackend {
 	 * The 'noAccess' and 'noListing' parameters works the same as in secure(),
 	 * except they are only applied *if* the directory/container had to be created.
 	 * These flags should always be set for directories that have private files.
+	 * However, setting them is not guaranteed to actually do anything.
+	 * Additional server configuration may be needed to achieve the desired effect.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - dir            : storage directory
 	 *   - noAccess       : try to deny file access (since 1.20)
@@ -620,6 +703,7 @@ abstract class FileBackend {
 		if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 			return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 		}
+		$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 		return $this->doPrepare( $params );
 	}
 
@@ -633,9 +717,11 @@ abstract class FileBackend {
 	 * the container it belongs to. FS backends might add .htaccess
 	 * files whereas key/value store backends might revoke container
 	 * access to the storage user representing end-users in web requests.
-	 * This is not guaranteed to actually do anything.
 	 *
-	 * @param $params Array
+	 * This is not guaranteed to actually make files or listings publically hidden.
+	 * Additional server configuration may be needed to achieve the desired effect.
+	 *
+	 * @param array $params
 	 * $params include:
 	 *   - dir            : storage directory
 	 *   - noAccess       : try to deny file access
@@ -647,6 +733,7 @@ abstract class FileBackend {
 		if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 			return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 		}
+		$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 		return $this->doSecure( $params );
 	}
 
@@ -662,7 +749,10 @@ abstract class FileBackend {
 	 * access to the storage user representing end-users in web requests.
 	 * This essentially can undo the result of secure() calls.
 	 *
-	 * @param $params Array
+	 * This is not guaranteed to actually make files or listings publically viewable.
+	 * Additional server configuration may be needed to achieve the desired effect.
+	 *
+	 * @param array $params
 	 * $params include:
 	 *   - dir            : storage directory
 	 *   - access         : try to allow file access
@@ -675,6 +765,7 @@ abstract class FileBackend {
 		if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 			return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 		}
+		$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 		return $this->doPublish( $params );
 	}
 
@@ -688,7 +779,7 @@ abstract class FileBackend {
 	 * Backends using key/value stores may do nothing unless the directory
 	 * is that of an empty container, in which case it will be deleted.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - dir            : storage directory
 	 *   - recursive      : recursively delete empty subdirectories first (since 1.20)
@@ -699,6 +790,7 @@ abstract class FileBackend {
 		if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 			return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 		}
+		$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 		return $this->doClean( $params );
 	}
 
@@ -708,10 +800,27 @@ abstract class FileBackend {
 	abstract protected function doClean( array $params );
 
 	/**
+	 * Enter file operation scope.
+	 * This just makes PHP ignore user aborts/disconnects until the return
+	 * value leaves scope. This returns null and does nothing in CLI mode.
+	 *
+	 * @return ScopedCallback|null
+	 */
+	final protected function getScopedPHPBehaviorForOps() {
+		if ( php_sapi_name() != 'cli' ) { // http://bugs.php.net/bug.php?id=47540
+			$old = ignore_user_abort( true ); // avoid half-finished operations
+			return new ScopedCallback( function() use ( $old ) {
+				ignore_user_abort( $old );
+			} );
+		}
+		return null;
+	}
+
+	/**
 	 * Check if a file exists at a storage path in the backend.
 	 * This returns false if only a directory exists at the path.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src    : source storage path
 	 *   - latest : use the latest available data
@@ -722,7 +831,7 @@ abstract class FileBackend {
 	/**
 	 * Get the last-modified timestamp of the file at a storage path.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src    : source storage path
 	 *   - latest : use the latest available data
@@ -734,18 +843,40 @@ abstract class FileBackend {
 	 * Get the contents of a file at a storage path in the backend.
 	 * This should be avoided for potentially large files.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src    : source storage path
 	 *   - latest : use the latest available data
 	 * @return string|bool Returns false on failure
 	 */
-	abstract public function getFileContents( array $params );
+	final public function getFileContents( array $params ) {
+		$contents = $this->getFileContentsMulti(
+			array( 'srcs' => array( $params['src'] ) ) + $params );
+
+		return $contents[$params['src']];
+	}
+
+	/**
+	 * Like getFileContents() except it takes an array of storage paths
+	 * and returns a map of storage paths to strings (or null on failure).
+	 * The map keys (paths) are in the same order as the provided list of paths.
+	 *
+	 * @see FileBackend::getFileContents()
+	 *
+	 * @param array $params
+	 * $params include:
+	 *   - srcs        : list of source storage paths
+	 *   - latest      : use the latest available data
+	 *   - parallelize : try to do operations in parallel when possible
+	 * @return Array Map of (path name => string or false on failure)
+	 * @since 1.20
+	 */
+	abstract public function getFileContentsMulti( array $params );
 
 	/**
 	 * Get the size (bytes) of a file at a storage path in the backend.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src    : source storage path
 	 *   - latest : use the latest available data
@@ -761,7 +892,7 @@ abstract class FileBackend {
 	 *   - size   : the file size (bytes)
 	 * Additional values may be included for internal use only.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src    : source storage path
 	 *   - latest : use the latest available data
@@ -772,7 +903,7 @@ abstract class FileBackend {
 	/**
 	 * Get a SHA-1 hash of the file at a storage path in the backend.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src    : source storage path
 	 *   - latest : use the latest available data
@@ -782,13 +913,13 @@ abstract class FileBackend {
 
 	/**
 	 * Get the properties of the file at a storage path in the backend.
-	 * Returns FSFile::placeholderProps() on failure.
+	 * This gives the result of FSFile::getProps() on a local copy of the file.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src    : source storage path
 	 *   - latest : use the latest available data
-	 * @return Array
+	 * @return Array Returns FSFile::placeholderProps() on failure
 	 */
 	abstract public function getFileProps( array $params );
 
@@ -799,7 +930,7 @@ abstract class FileBackend {
 	 * will be sent if streaming began, while none will be sent otherwise.
 	 * Implementations should flush the output buffer before sending data.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src     : source storage path
 	 *   - headers : list of additional HTTP headers to send on success
@@ -821,26 +952,89 @@ abstract class FileBackend {
 	 * In that later case, there are copies of the file that must stay in sync.
 	 * Additionally, further calls to this function may return the same file.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src    : source storage path
 	 *   - latest : use the latest available data
 	 * @return FSFile|null Returns null on failure
 	 */
-	abstract public function getLocalReference( array $params );
+	final public function getLocalReference( array $params ) {
+		$fsFiles = $this->getLocalReferenceMulti(
+			array( 'srcs' => array( $params['src'] ) ) + $params );
+
+		return $fsFiles[$params['src']];
+	}
+
+	/**
+	 * Like getLocalReference() except it takes an array of storage paths
+	 * and returns a map of storage paths to FSFile objects (or null on failure).
+	 * The map keys (paths) are in the same order as the provided list of paths.
+	 *
+	 * @see FileBackend::getLocalReference()
+	 *
+	 * @param array $params
+	 * $params include:
+	 *   - srcs        : list of source storage paths
+	 *   - latest      : use the latest available data
+	 *   - parallelize : try to do operations in parallel when possible
+	 * @return Array Map of (path name => FSFile or null on failure)
+	 * @since 1.20
+	 */
+	abstract public function getLocalReferenceMulti( array $params );
 
 	/**
 	 * Get a local copy on disk of the file at a storage path in the backend.
 	 * The temporary copy will have the same file extension as the source.
 	 * Temporary files may be purged when the file object falls out of scope.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * $params include:
 	 *   - src    : source storage path
 	 *   - latest : use the latest available data
 	 * @return TempFSFile|null Returns null on failure
 	 */
-	abstract public function getLocalCopy( array $params );
+	final public function getLocalCopy( array $params ) {
+		$tmpFiles = $this->getLocalCopyMulti(
+			array( 'srcs' => array( $params['src'] ) ) + $params );
+
+		return $tmpFiles[$params['src']];
+	}
+
+	/**
+	 * Like getLocalCopy() except it takes an array of storage paths and
+	 * returns a map of storage paths to TempFSFile objects (or null on failure).
+	 * The map keys (paths) are in the same order as the provided list of paths.
+	 *
+	 * @see FileBackend::getLocalCopy()
+	 *
+	 * @param array $params
+	 * $params include:
+	 *   - srcs        : list of source storage paths
+	 *   - latest      : use the latest available data
+	 *   - parallelize : try to do operations in parallel when possible
+	 * @return Array Map of (path name => TempFSFile or null on failure)
+	 * @since 1.20
+	 */
+	abstract public function getLocalCopyMulti( array $params );
+
+	/**
+	 * Return an HTTP URL to a given file that requires no authentication to use.
+	 * The URL may be pre-authenticated (via some token in the URL) and temporary.
+	 * This will return null if the backend cannot make an HTTP URL for the file.
+	 *
+	 * This is useful for key/value stores when using scripts that seek around
+	 * large files and those scripts (and the backend) support HTTP Range headers.
+	 * Otherwise, one would need to use getLocalReference(), which involves loading
+	 * the entire file on to local disk.
+	 *
+	 * @param array $params
+	 * $params include:
+	 *   - src : source storage path
+	 *   - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
+	 * @return string|null
+	 * @since 1.21
+	 */
+	abstract public function getFileHttpUrl( array $params );
 
 	/**
 	 * Check if a directory exists at a given storage path.
@@ -849,7 +1043,7 @@ abstract class FileBackend {
 	 *
 	 * Storage backends with eventual consistency might return stale data.
 	 *
-	 * @param $params array
+	 * @param array $params
 	 * $params include:
 	 *   - dir : storage directory
 	 * @return bool|null Returns null on failure
@@ -867,7 +1061,9 @@ abstract class FileBackend {
 	 *
 	 * Storage backends with eventual consistency might return stale data.
 	 *
-	 * @param $params array
+	 * Failures during iteration can result in FileBackendError exceptions (since 1.22).
+	 *
+	 * @param array $params
 	 * $params include:
 	 *   - dir     : storage directory
 	 *   - topOnly : only return direct child dirs of the directory
@@ -882,7 +1078,9 @@ abstract class FileBackend {
 	 *
 	 * Storage backends with eventual consistency might return stale data.
 	 *
-	 * @param $params array
+	 * Failures during iteration can result in FileBackendError exceptions (since 1.22).
+	 *
+	 * @param array $params
 	 * $params include:
 	 *   - dir : storage directory
 	 * @return Traversable|Array|null Returns null on failure
@@ -902,10 +1100,13 @@ abstract class FileBackend {
 	 *
 	 * Storage backends with eventual consistency might return stale data.
 	 *
-	 * @param $params array
+	 * Failures during iteration can result in FileBackendError exceptions (since 1.22).
+	 *
+	 * @param array $params
 	 * $params include:
-	 *   - dir     : storage directory
-	 *   - topOnly : only return direct child files of the directory (since 1.20)
+	 *   - dir        : storage directory
+	 *   - topOnly    : only return direct child files of the directory (since 1.20)
+	 *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
 	 * @return Traversable|Array|null Returns null on failure
 	 */
 	abstract public function getFileList( array $params );
@@ -916,9 +1117,12 @@ abstract class FileBackend {
 	 *
 	 * Storage backends with eventual consistency might return stale data.
 	 *
-	 * @param $params array
+	 * Failures during iteration can result in FileBackendError exceptions (since 1.22).
+	 *
+	 * @param array $params
 	 * $params include:
-	 *   - dir : storage directory
+	 *   - dir        : storage directory
+	 *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
 	 * @return Traversable|Array|null Returns null on failure
 	 * @since 1.20
 	 */
@@ -930,7 +1134,7 @@ abstract class FileBackend {
 	 * Preload persistent file stat and property cache into in-process cache.
 	 * This should be used when stat calls will be made on a known list of a many files.
 	 *
-	 * @param $paths Array Storage paths
+	 * @param array $paths Storage paths
 	 * @return void
 	 */
 	public function preloadCache( array $paths ) {}
@@ -939,7 +1143,7 @@ abstract class FileBackend {
 	 * Invalidate any in-process file stat and property cache.
 	 * If $paths is given, then only the cache for those files will be cleared.
 	 *
-	 * @param $paths Array Storage paths (optional)
+	 * @param array $paths Storage paths (optional)
 	 * @return void
 	 */
 	public function clearCache( array $paths = null ) {}
@@ -950,22 +1154,24 @@ abstract class FileBackend {
 	 *
 	 * Callers should consider using getScopedFileLocks() instead.
 	 *
-	 * @param $paths Array Storage paths
-	 * @param $type integer LockManager::LOCK_* constant
+	 * @param array $paths Storage paths
+	 * @param integer $type LockManager::LOCK_* constant
 	 * @return Status
 	 */
 	final public function lockFiles( array $paths, $type ) {
+		$paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
 		return $this->lockManager->lock( $paths, $type );
 	}
 
 	/**
 	 * Unlock the files at the given storage paths in the backend.
 	 *
-	 * @param $paths Array Storage paths
-	 * @param $type integer LockManager::LOCK_* constant
+	 * @param array $paths Storage paths
+	 * @param integer $type LockManager::LOCK_* constant
 	 * @return Status
 	 */
 	final public function unlockFiles( array $paths, $type ) {
+		$paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
 		return $this->lockManager->unlock( $paths, $type );
 	}
 
@@ -977,12 +1183,21 @@ abstract class FileBackend {
 	 * Once the return value goes out scope, the locks will be released and
 	 * the status updated. Unlock fatals will not change the status "OK" value.
 	 *
-	 * @param $paths Array Storage paths
-	 * @param $type integer LockManager::LOCK_* constant
-	 * @param $status Status Status to update on lock/unlock
+	 * @see ScopedLock::factory()
+	 *
+	 * @param array $paths List of storage paths or map of lock types to path lists
+	 * @param integer|string $type LockManager::LOCK_* constant or "mixed"
+	 * @param Status $status Status to update on lock/unlock
 	 * @return ScopedLock|null Returns null on failure
 	 */
 	final public function getScopedFileLocks( array $paths, $type, Status $status ) {
+		if ( $type === 'mixed' ) {
+			foreach ( $paths as &$typePaths ) {
+				$typePaths = array_map( 'FileBackend::normalizeStoragePath', $typePaths );
+			}
+		} else {
+			$paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
+		}
 		return ScopedLock::factory( $this->lockManager, $paths, $type, $status );
 	}
 
@@ -997,8 +1212,8 @@ abstract class FileBackend {
 	 *
 	 * @see FileBackend::doOperations()
 	 *
-	 * @param $ops Array List of file operations to FileBackend::doOperations()
-	 * @param $status Status Status to update on lock/unlock
+	 * @param array $ops List of file operations to FileBackend::doOperations()
+	 * @param Status $status Status to update on lock/unlock
 	 * @return Array List of ScopedFileLocks or null values
 	 * @since 1.20
 	 */
@@ -1016,6 +1231,17 @@ abstract class FileBackend {
 	}
 
 	/**
+	 * Get the storage path for the given container for this backend
+	 *
+	 * @param string $container Container name
+	 * @return string Storage path
+	 * @since 1.21
+	 */
+	final public function getContainerStoragePath( $container ) {
+		return $this->getRootStoragePath() . "/{$container}";
+	}
+
+	/**
 	 * Get the file journal object for this backend
 	 *
 	 * @return FileJournal
@@ -1028,7 +1254,7 @@ abstract class FileBackend {
 	 * Check if a given path is a "mwstore://" path.
 	 * This does not do any further validation or any existence checks.
 	 *
-	 * @param $path string
+	 * @param string $path
 	 * @return bool
 	 */
 	final public static function isStoragePath( $path ) {
@@ -1040,7 +1266,7 @@ abstract class FileBackend {
 	 * and a relative file path. The relative path may be the empty string.
 	 * This does not do any path normalization or traversal checks.
 	 *
-	 * @param $storagePath string
+	 * @param string $storagePath
 	 * @return Array (backend, container, rel object) or (null, null, null)
 	 */
 	final public static function splitStoragePath( $storagePath ) {
@@ -1062,7 +1288,7 @@ abstract class FileBackend {
 	 * Normalize a storage path by cleaning up directory separators.
 	 * Returns null if the path is not of the format of a valid storage path.
 	 *
-	 * @param $storagePath string
+	 * @param string $storagePath
 	 * @return string|null
 	 */
 	final public static function normalizeStoragePath( $storagePath ) {
@@ -1083,19 +1309,19 @@ abstract class FileBackend {
 	 * This returns a path like "mwstore://backend/container",
 	 * "mwstore://backend/container/...", or null if there is no parent.
 	 *
-	 * @param $storagePath string
+	 * @param string $storagePath
 	 * @return string|null
 	 */
 	final public static function parentStoragePath( $storagePath ) {
 		$storagePath = dirname( $storagePath );
-		list( $b, $cont, $rel ) = self::splitStoragePath( $storagePath );
+		list( , , $rel ) = self::splitStoragePath( $storagePath );
 		return ( $rel === null ) ? null : $storagePath;
 	}
 
 	/**
 	 * Get the final extension from a storage or FS path
 	 *
-	 * @param $path string
+	 * @param string $path
 	 * @return string
 	 */
 	final public static function extensionFromPath( $path ) {
@@ -1106,7 +1332,7 @@ abstract class FileBackend {
 	/**
 	 * Check if a relative path has no directory traversals
 	 *
-	 * @param $path string
+	 * @param string $path
 	 * @return bool
 	 * @since 1.20
 	 */
@@ -1117,8 +1343,9 @@ abstract class FileBackend {
 	/**
 	 * Build a Content-Disposition header value per RFC 6266.
 	 *
-	 * @param $type string One of (attachment, inline)
-	 * @param $filename string Suggested file name (should not contain slashes)
+	 * @param string $type One of (attachment, inline)
+	 * @param string $filename Suggested file name (should not contain slashes)
+	 * @throws MWException
 	 * @return string
 	 * @since 1.20
 	 */
@@ -1145,7 +1372,7 @@ abstract class FileBackend {
 	 *
 	 * This uses the same traversal protection as Title::secureAndSplit().
 	 *
-	 * @param $path string Storage path relative to a container
+	 * @param string $path Storage path relative to a container
 	 * @return string|null
 	 */
 	final protected static function normalizeContainerPath( $path ) {
@@ -1171,3 +1398,9 @@ abstract class FileBackend {
 		return $path;
 	}
 }
+
+/**
+ * @ingroup FileBackend
+ * @since 1.22
+ */
+class FileBackendError extends MWException {}
diff --git a/includes/filebackend/FileBackendGroup.php b/includes/filebackend/FileBackendGroup.php
index 8bbc96d0..be8a2076 100644
--- a/includes/filebackend/FileBackendGroup.php
+++ b/includes/filebackend/FileBackendGroup.php
@@ -87,21 +87,25 @@ class FileBackendGroup {
 			$thumbDir = isset( $info['thumbDir'] )
 				? $info['thumbDir']
 				: "{$directory}/thumb";
+			$transcodedDir = isset( $info['transcodedDir'] )
+				? $info['transcodedDir']
+				: "{$directory}/transcoded";
 			$fileMode = isset( $info['fileMode'] )
 				? $info['fileMode']
 				: 0644;
 			// Get the FS backend configuration
 			$autoBackends[] = array(
-				'name'           => $backendName,
-				'class'          => 'FSFileBackend',
-				'lockManager'    => 'fsLockManager',
+				'name' => $backendName,
+				'class' => 'FSFileBackend',
+				'lockManager' => 'fsLockManager',
 				'containerPaths' => array(
-					"{$repoName}-public"  => "{$directory}",
-					"{$repoName}-thumb"   => $thumbDir,
+					"{$repoName}-public" => "{$directory}",
+					"{$repoName}-thumb" => $thumbDir,
+					"{$repoName}-transcoded" => $transcodedDir,
 					"{$repoName}-deleted" => $deletedDir,
-					"{$repoName}-temp"    => "{$directory}/temp"
+					"{$repoName}-temp" => "{$directory}/temp"
 				),
-				'fileMode'       => $fileMode,
+				'fileMode' => $fileMode,
 			);
 		}
 
@@ -112,7 +116,7 @@ class FileBackendGroup {
 	/**
 	 * Register an array of file backend configurations
 	 *
-	 * @param $configs Array
+	 * @param Array $configs
 	 * @return void
 	 * @throws MWException
 	 */
@@ -122,15 +126,17 @@ class FileBackendGroup {
 				throw new MWException( "Cannot register a backend with no name." );
 			}
 			$name = $config['name'];
-			if ( !isset( $config['class'] ) ) {
+			if ( isset( $this->backends[$name] ) ) {
+				throw new MWException( "Backend with name `{$name}` already registered." );
+			} elseif ( !isset( $config['class'] ) ) {
 				throw new MWException( "Cannot register backend `{$name}` with no class." );
 			}
 			$class = $config['class'];
 
 			unset( $config['class'] ); // backend won't need this
 			$this->backends[$name] = array(
-				'class'    => $class,
-				'config'   => $config,
+				'class' => $class,
+				'config' => $config,
 				'instance' => null
 			);
 		}
@@ -139,7 +145,7 @@ class FileBackendGroup {
 	/**
 	 * Get the backend object with a given name
 	 *
-	 * @param $name string
+	 * @param string $name
 	 * @return FileBackend
 	 * @throws MWException
 	 */
@@ -159,7 +165,7 @@ class FileBackendGroup {
 	/**
 	 * Get the config array for a backend object with a given name
 	 *
-	 * @param $name string
+	 * @param string $name
 	 * @return Array
 	 * @throws MWException
 	 */
@@ -174,11 +180,11 @@ class FileBackendGroup {
 	/**
 	 * Get an appropriate backend object from a storage path
 	 *
-	 * @param $storagePath string
+	 * @param string $storagePath
 	 * @return FileBackend|null Backend or null on failure
 	 */
 	public function backendFromPath( $storagePath ) {
-		list( $backend, $c, $p ) = FileBackend::splitStoragePath( $storagePath );
+		list( $backend, , ) = FileBackend::splitStoragePath( $storagePath );
 		if ( $backend !== null && isset( $this->backends[$backend] ) ) {
 			return $this->get( $backend );
 		}
diff --git a/includes/filebackend/FileBackendMultiWrite.php b/includes/filebackend/FileBackendMultiWrite.php
index 4be03231..97584a71 100644
--- a/includes/filebackend/FileBackendMultiWrite.php
+++ b/includes/filebackend/FileBackendMultiWrite.php
@@ -62,7 +62,7 @@ class FileBackendMultiWrite extends FileBackend {
 	 * Additional $config params include:
 	 *   - backends       : Array of backend config and multi-backend settings.
 	 *                      Each value is the config used in the constructor of a
-	 *                          FileBackendStore class, but with these additional settings:
+	 *                      FileBackendStore class, but with these additional settings:
 	 *                        - class         : The name of the backend class
 	 *                        - isMultiMaster : This must be set for one backend.
 	 *                        - template:     : If given a backend name, this will use
@@ -75,10 +75,13 @@ class FileBackendMultiWrite extends FileBackend {
 	 *   - autoResync     : Automatically resync the clone backends to the master backend
 	 *                      when pre-operation sync checks fail. This should only be used
 	 *                      if the master backend is stable and not missing any files.
+	 *                      Use "conservative" to limit resyncing to copying newer master
+	 *                      backend files over older (or non-existing) clone backend files.
+	 *                      Cases that cannot be handled will result in operation abortion.
 	 *   - noPushQuickOps : (hack) Only apply doQuickOperations() to the master backend.
 	 *   - noPushDirConts : (hack) Only apply directory functions to the master backend.
 	 *
-	 * @param $config Array
+	 * @param Array $config
 	 * @throws MWException
 	 */
 	public function __construct( array $config ) {
@@ -86,7 +89,9 @@ class FileBackendMultiWrite extends FileBackend {
 		$this->syncChecks = isset( $config['syncChecks'] )
 			? $config['syncChecks']
 			: self::CHECK_SIZE;
-		$this->autoResync = !empty( $config['autoResync'] );
+		$this->autoResync = isset( $config['autoResync'] )
+			? $config['autoResync']
+			: false;
 		$this->noPushQuickOps = isset( $config['noPushQuickOps'] )
 			? $config['noPushQuickOps']
 			: false;
@@ -131,26 +136,15 @@ class FileBackendMultiWrite extends FileBackend {
 		}
 	}
 
-	/**
-	 * @see FileBackend::doOperationsInternal()
-	 * @return Status
-	 */
 	final protected function doOperationsInternal( array $ops, array $opts ) {
 		$status = Status::newGood();
 
 		$mbe = $this->backends[$this->masterIndex]; // convenience
 
-		// Get the paths to lock from the master backend
-		$realOps = $this->substOpBatchPaths( $ops, $mbe );
-		$paths = $mbe->getPathsToLockForOpsInternal( $mbe->getOperationsInternal( $realOps ) );
-		// Get the paths under the proxy backend's name
-		$paths['sh'] = $this->unsubstPaths( $paths['sh'] );
-		$paths['ex'] = $this->unsubstPaths( $paths['ex'] );
 		// Try to lock those files for the scope of this function...
 		if ( empty( $opts['nonLocking'] ) ) {
 			// Try to lock those files for the scope of this function...
-			$scopeLockS = $this->getScopedFileLocks( $paths['sh'], LockManager::LOCK_UW, $status );
-			$scopeLockE = $this->getScopedFileLocks( $paths['ex'], LockManager::LOCK_EX, $status );
+			$scopeLock = $this->getScopedLocksForOps( $ops, $status );
 			if ( !$status->isOK() ) {
 				return $status; // abort
 			}
@@ -177,12 +171,14 @@ class FileBackendMultiWrite extends FileBackend {
 			}
 		}
 		// Actually attempt the operation batch on the master backend...
+		$realOps = $this->substOpBatchPaths( $ops, $mbe );
 		$masterStatus = $mbe->doOperations( $realOps, $opts );
 		$status->merge( $masterStatus );
-		// Propagate the operations to the clone backends if there were no fatal errors.
-		// If $ops only had one operation, this might avoid backend inconsistencies.
-		// This also avoids inconsistency for expected errors (like "file already exists").
-		if ( !count( $masterStatus->getErrorsArray() ) ) {
+		// Propagate the operations to the clone backends if there were no unexpected errors
+		// and if there were either no expected errors or if the 'force' option was used.
+		// However, if nothing succeeded at all, then don't replicate any of the operations.
+		// If $ops only had one operation, this might avoid backend sync inconsistencies.
+		if ( $masterStatus->isOK() && $masterStatus->successCount > 0 ) {
 			foreach ( $this->backends as $index => $backend ) {
 				if ( $index !== $this->masterIndex ) { // not done already
 					$realOps = $this->substOpBatchPaths( $ops, $backend );
@@ -203,7 +199,7 @@ class FileBackendMultiWrite extends FileBackend {
 	/**
 	 * Check that a set of files are consistent across all internal backends
 	 *
-	 * @param $paths Array List of storage paths
+	 * @param array $paths List of storage paths
 	 * @return Status
 	 */
 	public function consistencyCheck( array $paths ) {
@@ -269,7 +265,7 @@ class FileBackendMultiWrite extends FileBackend {
 	/**
 	 * Check that a set of file paths are usable across all internal backends
 	 *
-	 * @param $paths Array List of storage paths
+	 * @param array $paths List of storage paths
 	 * @return Status
 	 */
 	public function accessibilityCheck( array $paths ) {
@@ -294,7 +290,7 @@ class FileBackendMultiWrite extends FileBackend {
 	 * Check that a set of files are consistent across all internal backends
 	 * and re-synchronize those files againt the "multi master" if needed.
 	 *
-	 * @param $paths Array List of storage paths
+	 * @param array $paths List of storage paths
 	 * @return Status
 	 */
 	public function resyncFiles( array $paths ) {
@@ -302,12 +298,12 @@ class FileBackendMultiWrite extends FileBackend {
 
 		$mBackend = $this->backends[$this->masterIndex];
 		foreach ( $paths as $path ) {
-			$mPath  = $this->substPaths( $path, $mBackend );
-			$mSha1  = $mBackend->getFileSha1Base36( array( 'src' => $mPath ) );
-			$mExist = $mBackend->fileExists( array( 'src' => $mPath ) );
-			// Check if the master backend is available...
-			if ( $mExist === null ) {
+			$mPath = $this->substPaths( $path, $mBackend );
+			$mSha1 = $mBackend->getFileSha1Base36( array( 'src' => $mPath, 'latest' => true ) );
+			$mStat = $mBackend->getFileStat( array( 'src' => $mPath, 'latest' => true ) );
+			if ( $mStat === null || ( $mSha1 !== false && !$mStat ) ) { // sanity
 				$status->fatal( 'backend-fail-internal', $this->name );
+				continue; // file is not available on the master backend...
 			}
 			// Check of all clone backends agree with the master...
 			foreach ( $this->backends as $index => $cBackend ) {
@@ -315,15 +311,31 @@ class FileBackendMultiWrite extends FileBackend {
 					continue; // master
 				}
 				$cPath = $this->substPaths( $path, $cBackend );
-				$cSha1 = $cBackend->getFileSha1Base36( array( 'src' => $cPath ) );
+				$cSha1 = $cBackend->getFileSha1Base36( array( 'src' => $cPath, 'latest' => true ) );
+				$cStat = $cBackend->getFileStat( array( 'src' => $cPath, 'latest' => true ) );
+				if ( $cStat === null || ( $cSha1 !== false && !$cStat ) ) { // sanity
+					$status->fatal( 'backend-fail-internal', $cBackend->getName() );
+					continue; // file is not available on the clone backend...
+				}
 				if ( $mSha1 === $cSha1 ) {
 					// already synced; nothing to do
-				} elseif ( $mSha1 ) { // file is in master
-					$fsFile = $mBackend->getLocalReference( array( 'src' => $mPath ) );
+				} elseif ( $mSha1 !== false ) { // file is in master
+					if ( $this->autoResync === 'conservative'
+						&& $cStat && $cStat['mtime'] > $mStat['mtime'] )
+					{
+						$status->fatal( 'backend-fail-synced', $path );
+						continue; // don't rollback data
+					}
+					$fsFile = $mBackend->getLocalReference(
+						array( 'src' => $mPath, 'latest' => true ) );
 					$status->merge( $cBackend->quickStore(
 						array( 'src' => $fsFile->getPath(), 'dst' => $cPath )
 					) );
-				} elseif ( $mExist === false ) { // file is not in master
+				} elseif ( $mStat === false ) { // file is not in master
+					if ( $this->autoResync === 'conservative' ) {
+						$status->fatal( 'backend-fail-synced', $path );
+						continue; // don't delete data
+					}
 					$status->merge( $cBackend->quickDelete( array( 'src' => $cPath ) ) );
 				}
 			}
@@ -335,14 +347,20 @@ class FileBackendMultiWrite extends FileBackend {
 	/**
 	 * Get a list of file storage paths to read or write for a list of operations
 	 *
-	 * @param $ops Array Same format as doOperations()
+	 * @param array $ops Same format as doOperations()
 	 * @return Array List of storage paths to files (does not include directories)
 	 */
 	protected function fileStoragePathsForOps( array $ops ) {
 		$paths = array();
 		foreach ( $ops as $op ) {
 			if ( isset( $op['src'] ) ) {
-				$paths[] = $op['src'];
+				// For things like copy/move/delete with "ignoreMissingSource" and there
+				// is no source file, nothing should happen and there should be no errors.
+				if ( empty( $op['ignoreMissingSource'] )
+					|| $this->fileExists( array( 'src' => $op['src'] ) ) )
+				{
+					$paths[] = $op['src'];
+				}
 			}
 			if ( isset( $op['srcs'] ) ) {
 				$paths = array_merge( $paths, $op['srcs'] );
@@ -351,15 +369,15 @@ class FileBackendMultiWrite extends FileBackend {
 				$paths[] = $op['dst'];
 			}
 		}
-		return array_unique( array_filter( $paths, 'FileBackend::isStoragePath' ) );
+		return array_values( array_unique( array_filter( $paths, 'FileBackend::isStoragePath' ) ) );
 	}
 
 	/**
 	 * Substitute the backend name in storage path parameters
 	 * for a set of operations with that of a given internal backend.
 	 *
-	 * @param $ops Array List of file operation arrays
-	 * @param $backend FileBackendStore
+	 * @param array $ops List of file operation arrays
+	 * @param FileBackendStore $backend
 	 * @return Array
 	 */
 	protected function substOpBatchPaths( array $ops, FileBackendStore $backend ) {
@@ -379,8 +397,8 @@ class FileBackendMultiWrite extends FileBackend {
 	/**
 	 * Same as substOpBatchPaths() but for a single operation
 	 *
-	 * @param $ops array File operation array
-	 * @param $backend FileBackendStore
+	 * @param array $ops File operation array
+	 * @param FileBackendStore $backend
 	 * @return Array
 	 */
 	protected function substOpPaths( array $ops, FileBackendStore $backend ) {
@@ -391,8 +409,8 @@ class FileBackendMultiWrite extends FileBackend {
 	/**
 	 * Substitute the backend of storage paths with an internal backend's name
 	 *
-	 * @param $paths Array|string List of paths or single string path
-	 * @param $backend FileBackendStore
+	 * @param array|string $paths List of paths or single string path
+	 * @param FileBackendStore $backend
 	 * @return Array|string
 	 */
 	protected function substPaths( $paths, FileBackendStore $backend ) {
@@ -406,7 +424,7 @@ class FileBackendMultiWrite extends FileBackend {
 	/**
 	 * Substitute the backend of internal storage paths with the proxy backend's name
 	 *
-	 * @param $paths Array|string List of paths or single string path
+	 * @param array|string $paths List of paths or single string path
 	 * @return Array|string
 	 */
 	protected function unsubstPaths( $paths ) {
@@ -417,10 +435,6 @@ class FileBackendMultiWrite extends FileBackend {
 		);
 	}
 
-	/**
-	 * @see FileBackend::doQuickOperationsInternal()
-	 * @return Status
-	 */
 	protected function doQuickOperationsInternal( array $ops ) {
 		$status = Status::newGood();
 		// Do the operations on the master backend; setting Status fields...
@@ -446,18 +460,14 @@ class FileBackendMultiWrite extends FileBackend {
 	}
 
 	/**
-	 * @param $path string Storage path
+	 * @param string $path Storage path
 	 * @return bool Path container should have dir changes pushed to all backends
 	 */
 	protected function replicateContainerDirChanges( $path ) {
-		list( $b, $shortCont, $r ) = self::splitStoragePath( $path );
+		list( , $shortCont, ) = self::splitStoragePath( $path );
 		return !in_array( $shortCont, $this->noPushDirConts );
 	}
 
-	/**
-	 * @see FileBackend::doPrepare()
-	 * @return Status
-	 */
 	protected function doPrepare( array $params ) {
 		$status = Status::newGood();
 		$replicate = $this->replicateContainerDirChanges( $params['dir'] );
@@ -470,11 +480,6 @@ class FileBackendMultiWrite extends FileBackend {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackend::doSecure()
-	 * @param $params array
-	 * @return Status
-	 */
 	protected function doSecure( array $params ) {
 		$status = Status::newGood();
 		$replicate = $this->replicateContainerDirChanges( $params['dir'] );
@@ -487,11 +492,6 @@ class FileBackendMultiWrite extends FileBackend {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackend::doPublish()
-	 * @param $params array
-	 * @return Status
-	 */
 	protected function doPublish( array $params ) {
 		$status = Status::newGood();
 		$replicate = $this->replicateContainerDirChanges( $params['dir'] );
@@ -504,11 +504,6 @@ class FileBackendMultiWrite extends FileBackend {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackend::doClean()
-	 * @param $params array
-	 * @return Status
-	 */
 	protected function doClean( array $params ) {
 		$status = Status::newGood();
 		$replicate = $this->replicateContainerDirChanges( $params['dir'] );
@@ -521,149 +516,100 @@ class FileBackendMultiWrite extends FileBackend {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackend::concatenate()
-	 * @param $params array
-	 * @return Status
-	 */
 	public function concatenate( array $params ) {
 		// We are writing to an FS file, so we don't need to do this per-backend
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->concatenate( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::fileExists()
-	 * @param $params array
-	 */
 	public function fileExists( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->fileExists( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::getFileTimestamp()
-	 * @param $params array
-	 * @return bool|string
-	 */
 	public function getFileTimestamp( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->getFileTimestamp( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::getFileSize()
-	 * @param $params array
-	 * @return bool|int
-	 */
 	public function getFileSize( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->getFileSize( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::getFileStat()
-	 * @param $params array
-	 * @return Array|bool|null
-	 */
 	public function getFileStat( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->getFileStat( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::getFileContents()
-	 * @param $params array
-	 * @return bool|string
-	 */
-	public function getFileContents( array $params ) {
+	public function getFileContentsMulti( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
-		return $this->backends[$this->masterIndex]->getFileContents( $realParams );
+		$contentsM = $this->backends[$this->masterIndex]->getFileContentsMulti( $realParams );
+
+		$contents = array(); // (path => FSFile) mapping using the proxy backend's name
+		foreach ( $contentsM as $path => $data ) {
+			$contents[$this->unsubstPaths( $path )] = $data;
+		}
+		return $contents;
 	}
 
-	/**
-	 * @see FileBackend::getFileSha1Base36()
-	 * @param $params array
-	 * @return bool|string
-	 */
 	public function getFileSha1Base36( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->getFileSha1Base36( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::getFileProps()
-	 * @param $params array
-	 * @return Array
-	 */
 	public function getFileProps( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->getFileProps( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::streamFile()
-	 * @param $params array
-	 * @return \Status
-	 */
 	public function streamFile( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->streamFile( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::getLocalReference()
-	 * @param $params array
-	 * @return FSFile|null
-	 */
-	public function getLocalReference( array $params ) {
+	public function getLocalReferenceMulti( array $params ) {
+		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
+		$fsFilesM = $this->backends[$this->masterIndex]->getLocalReferenceMulti( $realParams );
+
+		$fsFiles = array(); // (path => FSFile) mapping using the proxy backend's name
+		foreach ( $fsFilesM as $path => $fsFile ) {
+			$fsFiles[$this->unsubstPaths( $path )] = $fsFile;
+		}
+		return $fsFiles;
+	}
+
+	public function getLocalCopyMulti( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
-		return $this->backends[$this->masterIndex]->getLocalReference( $realParams );
+		$tempFilesM = $this->backends[$this->masterIndex]->getLocalCopyMulti( $realParams );
+
+		$tempFiles = array(); // (path => TempFSFile) mapping using the proxy backend's name
+		foreach ( $tempFilesM as $path => $tempFile ) {
+			$tempFiles[$this->unsubstPaths( $path )] = $tempFile;
+		}
+		return $tempFiles;
 	}
 
-	/**
-	 * @see FileBackend::getLocalCopy()
-	 * @param $params array
-	 * @return null|TempFSFile
-	 */
-	public function getLocalCopy( array $params ) {
+	public function getFileHttpUrl( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
-		return $this->backends[$this->masterIndex]->getLocalCopy( $realParams );
+		return $this->backends[$this->masterIndex]->getFileHttpUrl( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::directoryExists()
-	 * @param $params array
-	 * @return bool|null
-	 */
 	public function directoryExists( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->directoryExists( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::getSubdirectoryList()
-	 * @param $params array
-	 * @return Array|null|Traversable
-	 */
 	public function getDirectoryList( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->getDirectoryList( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::getFileList()
-	 * @param $params array
-	 * @return Array|null|\Traversable
-	 */
 	public function getFileList( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		return $this->backends[$this->masterIndex]->getFileList( $realParams );
 	}
 
-	/**
-	 * @see FileBackend::clearCache()
-	 */
 	public function clearCache( array $paths = null ) {
 		foreach ( $this->backends as $backend ) {
 			$realPaths = is_array( $paths ) ? $this->substPaths( $paths, $backend ) : null;
@@ -671,19 +617,17 @@ class FileBackendMultiWrite extends FileBackend {
 		}
 	}
 
-	/**
-	 * @see FileBackend::getScopedLocksForOps()
-	 */
 	public function getScopedLocksForOps( array $ops, Status $status ) {
-		$fileOps = $this->backends[$this->masterIndex]->getOperationsInternal( $ops );
+		$realOps = $this->substOpBatchPaths( $ops, $this->backends[$this->masterIndex] );
+		$fileOps = $this->backends[$this->masterIndex]->getOperationsInternal( $realOps );
 		// Get the paths to lock from the master backend
 		$paths = $this->backends[$this->masterIndex]->getPathsToLockForOpsInternal( $fileOps );
 		// Get the paths under the proxy backend's name
-		$paths['sh'] = $this->unsubstPaths( $paths['sh'] );
-		$paths['ex'] = $this->unsubstPaths( $paths['ex'] );
-		return array(
-			$this->getScopedFileLocks( $paths['sh'], LockManager::LOCK_UW, $status ),
-			$this->getScopedFileLocks( $paths['ex'], LockManager::LOCK_EX, $status )
+		$pbPaths = array(
+			LockManager::LOCK_UW => $this->unsubstPaths( $paths[LockManager::LOCK_UW] ),
+			LockManager::LOCK_EX => $this->unsubstPaths( $paths[LockManager::LOCK_EX] )
 		);
+		// Actually acquire the locks
+		return array( $this->getScopedFileLocks( $pbPaths, 'mixed', $status ) );
 	}
 }
diff --git a/includes/filebackend/FileBackendStore.php b/includes/filebackend/FileBackendStore.php
index 083dfea9..0921e99f 100644
--- a/includes/filebackend/FileBackendStore.php
+++ b/includes/filebackend/FileBackendStore.php
@@ -38,26 +38,43 @@
 abstract class FileBackendStore extends FileBackend {
 	/** @var BagOStuff */
 	protected $memCache;
-	/** @var ProcessCacheLRU */
-	protected $cheapCache; // Map of paths to small (RAM/disk) cache items
-	/** @var ProcessCacheLRU */
-	protected $expensiveCache; // Map of paths to large (RAM/disk) cache items
+	/** @var ProcessCacheLRU Map of paths to small (RAM/disk) cache items */
+	protected $cheapCache;
+	/** @var ProcessCacheLRU Map of paths to large (RAM/disk) cache items */
+	protected $expensiveCache;
 
-	/** @var Array Map of container names to sharding settings */
-	protected $shardViaHashLevels = array(); // (container name => config array)
+	/** @var Array Map of container names to sharding config */
+	protected $shardViaHashLevels = array();
+
+	/** @var callback Method to get the MIME type of files */
+	protected $mimeCallback;
 
 	protected $maxFileSize = 4294967296; // integer bytes (4GiB)
 
+	const CACHE_TTL = 10; // integer; TTL in seconds for process cache entries
+	const CACHE_CHEAP_SIZE = 300; // integer; max entries in "cheap cache"
+	const CACHE_EXPENSIVE_SIZE = 5; // integer; max entries in "expensive cache"
+
 	/**
 	 * @see FileBackend::__construct()
+	 * Additional $config params include:
+	 *   - mimeCallback : Callback that takes (storage path, content, file system path) and
+	 *                    returns the MIME type of the file or 'unknown/unknown'. The file
+	 *                    system path parameter should be used if the content one is null.
 	 *
-	 * @param $config Array
+	 * @param array $config
 	 */
 	public function __construct( array $config ) {
 		parent::__construct( $config );
-		$this->memCache       = new EmptyBagOStuff(); // disabled by default
-		$this->cheapCache     = new ProcessCacheLRU( 300 );
-		$this->expensiveCache = new ProcessCacheLRU( 5 );
+		$this->mimeCallback = isset( $config['mimeCallback'] )
+			? $config['mimeCallback']
+			: function( $storagePath, $content, $fsPath ) {
+				// @TODO: handle the case of extension-less files using the contents
+				return StreamFile::contentTypeFromPath( $storagePath ) ?: 'unknown/unknown';
+			};
+		$this->memCache = new EmptyBagOStuff(); // disabled by default
+		$this->cheapCache = new ProcessCacheLRU( self::CACHE_CHEAP_SIZE );
+		$this->expensiveCache = new ProcessCacheLRU( self::CACHE_EXPENSIVE_SIZE );
 	}
 
 	/**
@@ -72,124 +89,126 @@ abstract class FileBackendStore extends FileBackend {
 	}
 
 	/**
-	 * Check if a file can be created at a given storage path.
-	 * FS backends should check if the parent directory exists and the file is writable.
+	 * Check if a file can be created or changed at a given storage path.
+	 * FS backends should check if the parent directory exists, files can be
+	 * written under it, and that any file already there is writable.
 	 * Backends using key/value stores should check if the container exists.
 	 *
-	 * @param $storagePath string
+	 * @param string $storagePath
 	 * @return bool
 	 */
 	abstract public function isPathUsableInternal( $storagePath );
 
 	/**
 	 * Create a file in the backend with the given contents.
+	 * This will overwrite any file that exists at the destination.
 	 * Do not call this function from places outside FileBackend and FileOp.
 	 *
 	 * $params include:
-	 *   - content       : the raw file contents
-	 *   - dst           : destination storage path
-	 *   - overwrite     : overwrite any file that exists at the destination
-	 *   - disposition   : Content-Disposition header value for the destination
-	 *   - async         : Status will be returned immediately if supported.
-	 *                     If the status is OK, then its value field will be
-	 *                     set to a FileBackendStoreOpHandle object.
+	 *   - content     : the raw file contents
+	 *   - dst         : destination storage path
+	 *   - headers     : HTTP header name/value map
+	 *   - async       : Status will be returned immediately if supported.
+	 *                   If the status is OK, then its value field will be
+	 *                   set to a FileBackendStoreOpHandle object.
+	 *   - dstExists   : Whether a file exists at the destination (optimization).
+	 *                   Callers can use "false" if no existing file is being changed.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * @return Status
 	 */
 	final public function createInternal( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		if ( strlen( $params['content'] ) > $this->maxFileSizeInternal() ) {
 			$status = Status::newFatal( 'backend-fail-maxsize',
 				$params['dst'], $this->maxFileSizeInternal() );
 		} else {
 			$status = $this->doCreateInternal( $params );
 			$this->clearCache( array( $params['dst'] ) );
-			if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
+			if ( !isset( $params['dstExists'] ) || $params['dstExists'] ) {
 				$this->deleteFileCache( $params['dst'] ); // persistent cache
 			}
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
 	/**
 	 * @see FileBackendStore::createInternal()
+	 * @return Status
 	 */
 	abstract protected function doCreateInternal( array $params );
 
 	/**
 	 * Store a file into the backend from a file on disk.
+	 * This will overwrite any file that exists at the destination.
 	 * Do not call this function from places outside FileBackend and FileOp.
 	 *
 	 * $params include:
-	 *   - src           : source path on disk
-	 *   - dst           : destination storage path
-	 *   - overwrite     : overwrite any file that exists at the destination
-	 *   - disposition   : Content-Disposition header value for the destination
-	 *   - async         : Status will be returned immediately if supported.
-	 *                     If the status is OK, then its value field will be
-	 *                     set to a FileBackendStoreOpHandle object.
+	 *   - src         : source path on disk
+	 *   - dst         : destination storage path
+	 *   - headers     : HTTP header name/value map
+	 *   - async       : Status will be returned immediately if supported.
+	 *                   If the status is OK, then its value field will be
+	 *                   set to a FileBackendStoreOpHandle object.
+	 *   - dstExists   : Whether a file exists at the destination (optimization).
+	 *                   Callers can use "false" if no existing file is being changed.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * @return Status
 	 */
 	final public function storeInternal( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		if ( filesize( $params['src'] ) > $this->maxFileSizeInternal() ) {
 			$status = Status::newFatal( 'backend-fail-maxsize',
 				$params['dst'], $this->maxFileSizeInternal() );
 		} else {
 			$status = $this->doStoreInternal( $params );
 			$this->clearCache( array( $params['dst'] ) );
-			if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
+			if ( !isset( $params['dstExists'] ) || $params['dstExists'] ) {
 				$this->deleteFileCache( $params['dst'] ); // persistent cache
 			}
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
 	/**
 	 * @see FileBackendStore::storeInternal()
+	 * @return Status
 	 */
 	abstract protected function doStoreInternal( array $params );
 
 	/**
 	 * Copy a file from one storage path to another in the backend.
+	 * This will overwrite any file that exists at the destination.
 	 * Do not call this function from places outside FileBackend and FileOp.
 	 *
 	 * $params include:
-	 *   - src           : source storage path
-	 *   - dst           : destination storage path
-	 *   - overwrite     : overwrite any file that exists at the destination
-	 *   - disposition   : Content-Disposition header value for the destination
-	 *   - async         : Status will be returned immediately if supported.
-	 *                     If the status is OK, then its value field will be
-	 *                     set to a FileBackendStoreOpHandle object.
+	 *   - src                 : source storage path
+	 *   - dst                 : destination storage path
+	 *   - ignoreMissingSource : do nothing if the source file does not exist
+	 *   - headers             : HTTP header name/value map
+	 *   - async               : Status will be returned immediately if supported.
+	 *                           If the status is OK, then its value field will be
+	 *                           set to a FileBackendStoreOpHandle object.
+	 *   - dstExists           : Whether a file exists at the destination (optimization).
+	 *                           Callers can use "false" if no existing file is being changed.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * @return Status
 	 */
 	final public function copyInternal( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = $this->doCopyInternal( $params );
 		$this->clearCache( array( $params['dst'] ) );
-		if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
+		if ( !isset( $params['dstExists'] ) || $params['dstExists'] ) {
 			$this->deleteFileCache( $params['dst'] ); // persistent cache
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
 	/**
 	 * @see FileBackendStore::copyInternal()
+	 * @return Status
 	 */
 	abstract protected function doCopyInternal( array $params );
 
@@ -204,52 +223,50 @@ abstract class FileBackendStore extends FileBackend {
 	 *                           If the status is OK, then its value field will be
 	 *                           set to a FileBackendStoreOpHandle object.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * @return Status
 	 */
 	final public function deleteInternal( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = $this->doDeleteInternal( $params );
 		$this->clearCache( array( $params['src'] ) );
 		$this->deleteFileCache( $params['src'] ); // persistent cache
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
 	/**
 	 * @see FileBackendStore::deleteInternal()
+	 * @return Status
 	 */
 	abstract protected function doDeleteInternal( array $params );
 
 	/**
 	 * Move a file from one storage path to another in the backend.
+	 * This will overwrite any file that exists at the destination.
 	 * Do not call this function from places outside FileBackend and FileOp.
 	 *
 	 * $params include:
-	 *   - src           : source storage path
-	 *   - dst           : destination storage path
-	 *   - overwrite     : overwrite any file that exists at the destination
-	 *   - disposition   : Content-Disposition header value for the destination
-	 *   - async         : Status will be returned immediately if supported.
-	 *                     If the status is OK, then its value field will be
-	 *                     set to a FileBackendStoreOpHandle object.
+	 *   - src                 : source storage path
+	 *   - dst                 : destination storage path
+	 *   - ignoreMissingSource : do nothing if the source file does not exist
+	 *   - headers             : HTTP header name/value map
+	 *   - async               : Status will be returned immediately if supported.
+	 *                           If the status is OK, then its value field will be
+	 *                           set to a FileBackendStoreOpHandle object.
+	 *   - dstExists           : Whether a file exists at the destination (optimization).
+	 *                           Callers can use "false" if no existing file is being changed.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * @return Status
 	 */
 	final public function moveInternal( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = $this->doMoveInternal( $params );
 		$this->clearCache( array( $params['src'], $params['dst'] ) );
 		$this->deleteFileCache( $params['src'] ); // persistent cache
-		if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
+		if ( !isset( $params['dstExists'] ) || $params['dstExists'] ) {
 			$this->deleteFileCache( $params['dst'] ); // persistent cache
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -259,10 +276,12 @@ abstract class FileBackendStore extends FileBackend {
 	 */
 	protected function doMoveInternal( array $params ) {
 		unset( $params['async'] ); // two steps, won't work here :)
+		$nsrc = FileBackend::normalizeStoragePath( $params['src'] );
+		$ndst = FileBackend::normalizeStoragePath( $params['dst'] );
 		// Copy source to dest
 		$status = $this->copyInternal( $params );
-		if ( $status->isOK() ) {
-			// Delete source (only fails due to races or medium going down)
+		if ( $nsrc !== $ndst && $status->isOK() ) {
+			// Delete source (only fails due to races or network problems)
 			$status->merge( $this->deleteInternal( array( 'src' => $params['src'] ) ) );
 			$status->setResult( true, $status->value ); // ignore delete() errors
 		}
@@ -270,23 +289,52 @@ abstract class FileBackendStore extends FileBackend {
 	}
 
 	/**
-	 * No-op file operation that does nothing.
+	 * Alter metadata for a file at the storage path.
 	 * Do not call this function from places outside FileBackend and FileOp.
 	 *
-	 * @param $params Array
+	 * $params include:
+	 *   - src           : source storage path
+	 *   - headers       : HTTP header name/value map
+	 *   - async         : Status will be returned immediately if supported.
+	 *                     If the status is OK, then its value field will be
+	 *                     set to a FileBackendStoreOpHandle object.
+	 *
+	 * @param array $params
 	 * @return Status
 	 */
-	final public function nullInternal( array $params ) {
+	final public function describeInternal( array $params ) {
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
+		if ( count( $params['headers'] ) ) {
+			$status = $this->doDescribeInternal( $params );
+			$this->clearCache( array( $params['src'] ) );
+			$this->deleteFileCache( $params['src'] ); // persistent cache
+		} else {
+			$status = Status::newGood(); // nothing to do
+		}
+		return $status;
+	}
+
+	/**
+	 * @see FileBackendStore::describeInternal()
+	 * @return Status
+	 */
+	protected function doDescribeInternal( array $params ) {
 		return Status::newGood();
 	}
 
 	/**
-	 * @see FileBackend::concatenate()
+	 * No-op file operation that does nothing.
+	 * Do not call this function from places outside FileBackend and FileOp.
+	 *
+	 * @param array $params
 	 * @return Status
 	 */
+	final public function nullInternal( array $params ) {
+		return Status::newGood();
+	}
+
 	final public function concatenate( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = Status::newGood();
 
 		// Try to lock the source files for the scope of this function
@@ -302,8 +350,6 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -314,31 +360,41 @@ abstract class FileBackendStore extends FileBackend {
 	protected function doConcatenate( array $params ) {
 		$status = Status::newGood();
 		$tmpPath = $params['dst']; // convenience
+		unset( $params['latest'] ); // sanity
 
 		// Check that the specified temp file is valid...
 		wfSuppressWarnings();
-		$ok = ( is_file( $tmpPath ) && !filesize( $tmpPath ) );
+		$ok = ( is_file( $tmpPath ) && filesize( $tmpPath ) == 0 );
 		wfRestoreWarnings();
 		if ( !$ok ) { // not present or not empty
 			$status->fatal( 'backend-fail-opentemp', $tmpPath );
 			return $status;
 		}
 
-		// Build up the temp file using the source chunks (in order)...
+		// Get local FS versions of the chunks needed for the concatenation...
+		$fsFiles = $this->getLocalReferenceMulti( $params );
+		foreach ( $fsFiles as $path => &$fsFile ) {
+			if ( !$fsFile ) { // chunk failed to download?
+				$fsFile = $this->getLocalReference( array( 'src' => $path ) );
+				if ( !$fsFile ) { // retry failed?
+					$status->fatal( 'backend-fail-read', $path );
+					return $status;
+				}
+			}
+		}
+		unset( $fsFile ); // unset reference so we can reuse $fsFile
+
+		// Get a handle for the destination temp file
 		$tmpHandle = fopen( $tmpPath, 'ab' );
 		if ( $tmpHandle === false ) {
 			$status->fatal( 'backend-fail-opentemp', $tmpPath );
 			return $status;
 		}
-		foreach ( $params['srcs'] as $virtualSource ) {
-			// Get a local FS version of the chunk
-			$tmpFile = $this->getLocalReference( array( 'src' => $virtualSource ) );
-			if ( !$tmpFile ) {
-				$status->fatal( 'backend-fail-read', $virtualSource );
-				return $status;
-			}
+
+		// Build up the temp file using the source chunks (in order)...
+		foreach ( $fsFiles as $virtualSource => $fsFile ) {
 			// Get a handle to the local FS version
-			$sourceHandle = fopen( $tmpFile->getPath(), 'r' );
+			$sourceHandle = fopen( $fsFile->getPath(), 'rb' );
 			if ( $sourceHandle === false ) {
 				fclose( $tmpHandle );
 				$status->fatal( 'backend-fail-read', $virtualSource );
@@ -363,20 +419,13 @@ abstract class FileBackendStore extends FileBackend {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackend::doPrepare()
-	 * @return Status
-	 */
 	final protected function doPrepare( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
-
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = Status::newGood();
+
 		list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 		if ( $dir === null ) {
 			$status->fatal( 'backend-fail-invalidpath', $params['dir'] );
-			wfProfileOut( __METHOD__ . '-' . $this->name );
-			wfProfileOut( __METHOD__ );
 			return $status; // invalid storage path
 		}
 
@@ -384,14 +433,12 @@ abstract class FileBackendStore extends FileBackend {
 			$status->merge( $this->doPrepareInternal( $fullCont, $dir, $params ) );
 		} else { // directory is on several shards
 			wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
-			list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
+			list( , $shortCont, ) = self::splitStoragePath( $params['dir'] );
 			foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 				$status->merge( $this->doPrepareInternal( "{$fullCont}{$suffix}", $dir, $params ) );
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -403,20 +450,13 @@ abstract class FileBackendStore extends FileBackend {
 		return Status::newGood();
 	}
 
-	/**
-	 * @see FileBackend::doSecure()
-	 * @return Status
-	 */
 	final protected function doSecure( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = Status::newGood();
 
 		list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 		if ( $dir === null ) {
 			$status->fatal( 'backend-fail-invalidpath', $params['dir'] );
-			wfProfileOut( __METHOD__ . '-' . $this->name );
-			wfProfileOut( __METHOD__ );
 			return $status; // invalid storage path
 		}
 
@@ -424,14 +464,12 @@ abstract class FileBackendStore extends FileBackend {
 			$status->merge( $this->doSecureInternal( $fullCont, $dir, $params ) );
 		} else { // directory is on several shards
 			wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
-			list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
+			list( , $shortCont, ) = self::splitStoragePath( $params['dir'] );
 			foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 				$status->merge( $this->doSecureInternal( "{$fullCont}{$suffix}", $dir, $params ) );
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -443,20 +481,13 @@ abstract class FileBackendStore extends FileBackend {
 		return Status::newGood();
 	}
 
-	/**
-	 * @see FileBackend::doPublish()
-	 * @return Status
-	 */
 	final protected function doPublish( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = Status::newGood();
 
 		list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 		if ( $dir === null ) {
 			$status->fatal( 'backend-fail-invalidpath', $params['dir'] );
-			wfProfileOut( __METHOD__ . '-' . $this->name );
-			wfProfileOut( __METHOD__ );
 			return $status; // invalid storage path
 		}
 
@@ -464,14 +495,12 @@ abstract class FileBackendStore extends FileBackend {
 			$status->merge( $this->doPublishInternal( $fullCont, $dir, $params ) );
 		} else { // directory is on several shards
 			wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
-			list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
+			list( , $shortCont, ) = self::splitStoragePath( $params['dir'] );
 			foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 				$status->merge( $this->doPublishInternal( "{$fullCont}{$suffix}", $dir, $params ) );
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -483,13 +512,8 @@ abstract class FileBackendStore extends FileBackend {
 		return Status::newGood();
 	}
 
-	/**
-	 * @see FileBackend::doClean()
-	 * @return Status
-	 */
 	final protected function doClean( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = Status::newGood();
 
 		// Recursive: first delete all empty subdirs recursively
@@ -500,14 +524,13 @@ abstract class FileBackendStore extends FileBackend {
 					$subDir = $params['dir'] . "/{$subDirRel}"; // full path
 					$status->merge( $this->doClean( array( 'dir' => $subDir ) + $params ) );
 				}
+				unset( $subDirsRel ); // free directory for rmdir() on Windows (for FS backends)
 			}
 		}
 
 		list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 		if ( $dir === null ) {
 			$status->fatal( 'backend-fail-invalidpath', $params['dir'] );
-			wfProfileOut( __METHOD__ . '-' . $this->name );
-			wfProfileOut( __METHOD__ );
 			return $status; // invalid storage path
 		}
 
@@ -515,8 +538,6 @@ abstract class FileBackendStore extends FileBackend {
 		$filesLockEx = array( $params['dir'] );
 		$scopedLockE = $this->getScopedFileLocks( $filesLockEx, LockManager::LOCK_EX, $status );
 		if ( !$status->isOK() ) {
-			wfProfileOut( __METHOD__ . '-' . $this->name );
-			wfProfileOut( __METHOD__ );
 			return $status; // abort
 		}
 
@@ -525,15 +546,13 @@ abstract class FileBackendStore extends FileBackend {
 			$this->deleteContainerCache( $fullCont ); // purge cache
 		} else { // directory is on several shards
 			wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
-			list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
+			list( , $shortCont, ) = self::splitStoragePath( $params['dir'] );
 			foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 				$status->merge( $this->doCleanInternal( "{$fullCont}{$suffix}", $dir, $params ) );
 				$this->deleteContainerCache( "{$fullCont}{$suffix}" ); // purge cache
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -545,68 +564,46 @@ abstract class FileBackendStore extends FileBackend {
 		return Status::newGood();
 	}
 
-	/**
-	 * @see FileBackend::fileExists()
-	 * @return bool|null
-	 */
 	final public function fileExists( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$stat = $this->getFileStat( $params );
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return ( $stat === null ) ? null : (bool)$stat; // null => failure
 	}
 
-	/**
-	 * @see FileBackend::getFileTimestamp()
-	 * @return bool
-	 */
 	final public function getFileTimestamp( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$stat = $this->getFileStat( $params );
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $stat ? $stat['mtime'] : false;
 	}
 
-	/**
-	 * @see FileBackend::getFileSize()
-	 * @return bool
-	 */
 	final public function getFileSize( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$stat = $this->getFileStat( $params );
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $stat ? $stat['size'] : false;
 	}
 
-	/**
-	 * @see FileBackend::getFileStat()
-	 * @return bool
-	 */
 	final public function getFileStat( array $params ) {
 		$path = self::normalizeStoragePath( $params['src'] );
 		if ( $path === null ) {
 			return false; // invalid storage path
 		}
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$latest = !empty( $params['latest'] ); // use latest data?
-		if ( !$this->cheapCache->has( $path, 'stat' ) ) {
+		if ( !$this->cheapCache->has( $path, 'stat', self::CACHE_TTL ) ) {
 			$this->primeFileCache( array( $path ) ); // check persistent cache
 		}
-		if ( $this->cheapCache->has( $path, 'stat' ) ) {
+		if ( $this->cheapCache->has( $path, 'stat', self::CACHE_TTL ) ) {
 			$stat = $this->cheapCache->get( $path, 'stat' );
 			// If we want the latest data, check that this cached
 			// value was in fact fetched with the latest available data.
-			if ( !$latest || $stat['latest'] ) {
-				wfProfileOut( __METHOD__ . '-' . $this->name );
-				wfProfileOut( __METHOD__ );
-				return $stat;
+			if ( is_array( $stat ) ) {
+				if ( !$latest || $stat['latest'] ) {
+					return $stat;
+				}
+			} elseif ( in_array( $stat, array( 'NOT_EXIST', 'NOT_EXIST_LATEST' ) ) ) {
+				if ( !$latest || $stat === 'NOT_EXIST_LATEST' ) {
+					return false;
+				}
 			}
 		}
 		wfProfileIn( __METHOD__ . '-miss' );
@@ -614,7 +611,7 @@ abstract class FileBackendStore extends FileBackend {
 		$stat = $this->doGetFileStat( $params );
 		wfProfileOut( __METHOD__ . '-miss-' . $this->name );
 		wfProfileOut( __METHOD__ . '-miss' );
-		if ( is_array( $stat ) ) { // don't cache negatives
+		if ( is_array( $stat ) ) { // file exists
 			$stat['latest'] = $latest;
 			$this->cheapCache->set( $path, 'stat', $stat );
 			$this->setFileCache( $path, $stat ); // update persistent cache
@@ -622,11 +619,14 @@ abstract class FileBackendStore extends FileBackend {
 				$this->cheapCache->set( $path, 'sha1',
 					array( 'hash' => $stat['sha1'], 'latest' => $latest ) );
 			}
-		} else {
+		} elseif ( $stat === false ) { // file does not exist
+			$this->cheapCache->set( $path, 'stat', $latest ? 'NOT_EXIST_LATEST' : 'NOT_EXIST' );
+			$this->cheapCache->set( $path, 'sha1', // the SHA-1 must be false too
+				array( 'hash' => false, 'latest' => $latest ) );
 			wfDebug( __METHOD__ . ": File $path does not exist.\n" );
+		} else { // an error occurred
+			wfDebug( __METHOD__ . ": Could not stat file $path.\n" );
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $stat;
 	}
 
@@ -635,46 +635,41 @@ abstract class FileBackendStore extends FileBackend {
 	 */
 	abstract protected function doGetFileStat( array $params );
 
+	public function getFileContentsMulti( array $params ) {
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
+
+		$params = $this->setConcurrencyFlags( $params );
+		$contents = $this->doGetFileContentsMulti( $params );
+
+		return $contents;
+	}
+
 	/**
-	 * @see FileBackend::getFileContents()
-	 * @return bool|string
+	 * @see FileBackendStore::getFileContentsMulti()
+	 * @return Array
 	 */
-	public function getFileContents( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
-		$tmpFile = $this->getLocalReference( $params );
-		if ( !$tmpFile ) {
-			wfProfileOut( __METHOD__ . '-' . $this->name );
-			wfProfileOut( __METHOD__ );
-			return false;
+	protected function doGetFileContentsMulti( array $params ) {
+		$contents = array();
+		foreach ( $this->doGetLocalReferenceMulti( $params ) as $path => $fsFile ) {
+			wfSuppressWarnings();
+			$contents[$path] = $fsFile ? file_get_contents( $fsFile->getPath() ) : false;
+			wfRestoreWarnings();
 		}
-		wfSuppressWarnings();
-		$data = file_get_contents( $tmpFile->getPath() );
-		wfRestoreWarnings();
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
-		return $data;
+		return $contents;
 	}
 
-	/**
-	 * @see FileBackend::getFileSha1Base36()
-	 * @return bool|string
-	 */
 	final public function getFileSha1Base36( array $params ) {
 		$path = self::normalizeStoragePath( $params['src'] );
 		if ( $path === null ) {
 			return false; // invalid storage path
 		}
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$latest = !empty( $params['latest'] ); // use latest data?
-		if ( $this->cheapCache->has( $path, 'sha1' ) ) {
+		if ( $this->cheapCache->has( $path, 'sha1', self::CACHE_TTL ) ) {
 			$stat = $this->cheapCache->get( $path, 'sha1' );
 			// If we want the latest data, check that this cached
 			// value was in fact fetched with the latest available data.
 			if ( !$latest || $stat['latest'] ) {
-				wfProfileOut( __METHOD__ . '-' . $this->name );
-				wfProfileOut( __METHOD__ );
 				return $stat['hash'];
 			}
 		}
@@ -683,12 +678,7 @@ abstract class FileBackendStore extends FileBackend {
 		$hash = $this->doGetFileSha1Base36( $params );
 		wfProfileOut( __METHOD__ . '-miss-' . $this->name );
 		wfProfileOut( __METHOD__ . '-miss' );
-		if ( $hash ) { // don't cache negatives
-			$this->cheapCache->set( $path, 'sha1',
-				array( 'hash' => $hash, 'latest' => $latest ) );
-		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
+		$this->cheapCache->set( $path, 'sha1', array( 'hash' => $hash, 'latest' => $latest ) );
 		return $hash;
 	}
 
@@ -705,59 +695,80 @@ abstract class FileBackendStore extends FileBackend {
 		}
 	}
 
-	/**
-	 * @see FileBackend::getFileProps()
-	 * @return Array
-	 */
 	final public function getFileProps( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$fsFile = $this->getLocalReference( $params );
 		$props = $fsFile ? $fsFile->getProps() : FSFile::placeholderProps();
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $props;
 	}
 
-	/**
-	 * @see FileBackend::getLocalReference()
-	 * @return TempFSFile|null
-	 */
-	public function getLocalReference( array $params ) {
-		$path = self::normalizeStoragePath( $params['src'] );
-		if ( $path === null ) {
-			return null; // invalid storage path
-		}
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+	final public function getLocalReferenceMulti( array $params ) {
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
+
+		$params = $this->setConcurrencyFlags( $params );
+
+		$fsFiles = array(); // (path => FSFile)
 		$latest = !empty( $params['latest'] ); // use latest data?
-		if ( $this->expensiveCache->has( $path, 'localRef' ) ) {
-			$val = $this->expensiveCache->get( $path, 'localRef' );
-			// If we want the latest data, check that this cached
-			// value was in fact fetched with the latest available data.
-			if ( !$latest || $val['latest'] ) {
-				wfProfileOut( __METHOD__ . '-' . $this->name );
-				wfProfileOut( __METHOD__ );
-				return $val['object'];
+		// Reuse any files already in process cache...
+		foreach ( $params['srcs'] as $src ) {
+			$path = self::normalizeStoragePath( $src );
+			if ( $path === null ) {
+				$fsFiles[$src] = null; // invalid storage path
+			} elseif ( $this->expensiveCache->has( $path, 'localRef' ) ) {
+				$val = $this->expensiveCache->get( $path, 'localRef' );
+				// If we want the latest data, check that this cached
+				// value was in fact fetched with the latest available data.
+				if ( !$latest || $val['latest'] ) {
+					$fsFiles[$src] = $val['object'];
+				}
 			}
 		}
-		$tmpFile = $this->getLocalCopy( $params );
-		if ( $tmpFile ) { // don't cache negatives
-			$this->expensiveCache->set( $path, 'localRef',
-				array( 'object' => $tmpFile, 'latest' => $latest ) );
+		// Fetch local references of any remaning files...
+		$params['srcs'] = array_diff( $params['srcs'], array_keys( $fsFiles ) );
+		foreach ( $this->doGetLocalReferenceMulti( $params ) as $path => $fsFile ) {
+			$fsFiles[$path] = $fsFile;
+			if ( $fsFile ) { // update the process cache...
+				$this->expensiveCache->set( $path, 'localRef',
+					array( 'object' => $fsFile, 'latest' => $latest ) );
+			}
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
-		return $tmpFile;
+
+		return $fsFiles;
 	}
 
 	/**
-	 * @see FileBackend::streamFile()
-	 * @return Status
+	 * @see FileBackendStore::getLocalReferenceMulti()
+	 * @return Array
+	 */
+	protected function doGetLocalReferenceMulti( array $params ) {
+		return $this->doGetLocalCopyMulti( $params );
+	}
+
+	final public function getLocalCopyMulti( array $params ) {
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
+
+		$params = $this->setConcurrencyFlags( $params );
+		$tmpFiles = $this->doGetLocalCopyMulti( $params );
+
+		return $tmpFiles;
+	}
+
+	/**
+	 * @see FileBackendStore::getLocalCopyMulti()
+	 * @return Array
+	 */
+	abstract protected function doGetLocalCopyMulti( array $params );
+
+	/**
+	 * @see FileBackend::getFileHttpUrl()
+	 * @return string|null
 	 */
+	public function getFileHttpUrl( array $params ) {
+		return null; // not supported
+	}
+
 	final public function streamFile( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = Status::newGood();
 
 		$info = $this->getFileStat( $params );
@@ -776,12 +787,18 @@ abstract class FileBackendStore extends FileBackend {
 			$status = $this->doStreamFile( $params );
 			wfProfileOut( __METHOD__ . '-send-' . $this->name );
 			wfProfileOut( __METHOD__ . '-send' );
+			if ( !$status->isOK() ) {
+				// Per bug 41113, nasty things can happen if bad cache entries get
+				// stuck in cache. It's also possible that this error can come up
+				// with simple race conditions. Clear out the stat cache to be safe.
+				$this->clearCache( array( $params['src'] ) );
+				$this->deleteFileCache( $params['src'] );
+				trigger_error( "Bad stat cache or race condition for file {$params['src']}." );
+			}
 		} else {
 			$status->fatal( 'backend-fail-stream', $params['src'] );
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -802,10 +819,6 @@ abstract class FileBackendStore extends FileBackend {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackend::directoryExists()
-	 * @return bool|null
-	 */
 	final public function directoryExists( array $params ) {
 		list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 		if ( $dir === null ) {
@@ -815,7 +828,7 @@ abstract class FileBackendStore extends FileBackend {
 			return $this->doDirectoryExists( $fullCont, $dir, $params );
 		} else { // directory is on several shards
 			wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
-			list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
+			list( , $shortCont, ) = self::splitStoragePath( $params['dir'] );
 			$res = false; // response
 			foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 				$exists = $this->doDirectoryExists( "{$fullCont}{$suffix}", $dir, $params );
@@ -833,17 +846,13 @@ abstract class FileBackendStore extends FileBackend {
 	/**
 	 * @see FileBackendStore::directoryExists()
 	 *
-	 * @param $container string Resolved container name
-	 * @param $dir string Resolved path relative to container
-	 * @param $params Array
+	 * @param string $container Resolved container name
+	 * @param string $dir Resolved path relative to container
+	 * @param array $params
 	 * @return bool|null
 	 */
 	abstract protected function doDirectoryExists( $container, $dir, array $params );
 
-	/**
-	 * @see FileBackend::getDirectoryList()
-	 * @return Traversable|Array|null Returns null on failure
-	 */
 	final public function getDirectoryList( array $params ) {
 		list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 		if ( $dir === null ) { // invalid storage path
@@ -855,7 +864,7 @@ abstract class FileBackendStore extends FileBackend {
 		} else {
 			wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 			// File listing spans multiple containers/shards
-			list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
+			list( , $shortCont, ) = self::splitStoragePath( $params['dir'] );
 			return new FileBackendStoreShardDirIterator( $this,
 				$fullCont, $dir, $this->getContainerSuffixes( $shortCont ), $params );
 		}
@@ -866,17 +875,13 @@ abstract class FileBackendStore extends FileBackend {
 	 *
 	 * @see FileBackendStore::getDirectoryList()
 	 *
-	 * @param $container string Resolved container name
-	 * @param $dir string Resolved path relative to container
-	 * @param $params Array
+	 * @param string $container Resolved container name
+	 * @param string $dir Resolved path relative to container
+	 * @param array $params
 	 * @return Traversable|Array|null Returns null on failure
 	 */
 	abstract public function getDirectoryListInternal( $container, $dir, array $params );
 
-	/**
-	 * @see FileBackend::getFileList()
-	 * @return Traversable|Array|null Returns null on failure
-	 */
 	final public function getFileList( array $params ) {
 		list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 		if ( $dir === null ) { // invalid storage path
@@ -888,7 +893,7 @@ abstract class FileBackendStore extends FileBackend {
 		} else {
 			wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 			// File listing spans multiple containers/shards
-			list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
+			list( , $shortCont, ) = self::splitStoragePath( $params['dir'] );
 			return new FileBackendStoreShardFileIterator( $this,
 				$fullCont, $dir, $this->getContainerSuffixes( $shortCont ), $params );
 		}
@@ -899,9 +904,9 @@ abstract class FileBackendStore extends FileBackend {
 	 *
 	 * @see FileBackendStore::getFileList()
 	 *
-	 * @param $container string Resolved container name
-	 * @param $dir string Resolved path relative to container
-	 * @param $params Array
+	 * @param string $container Resolved container name
+	 * @param string $dir Resolved path relative to container
+	 * @param array $params
 	 * @return Traversable|Array|null Returns null on failure
 	 */
 	abstract public function getFileListInternal( $container, $dir, array $params );
@@ -913,18 +918,19 @@ abstract class FileBackendStore extends FileBackend {
 	 * The result must have the same number of items as the input.
 	 * An exception is thrown if an unsupported operation is requested.
 	 *
-	 * @param $ops Array Same format as doOperations()
+	 * @param array $ops Same format as doOperations()
 	 * @return Array List of FileOp objects
 	 * @throws MWException
 	 */
 	final public function getOperationsInternal( array $ops ) {
 		$supportedOps = array(
-			'store'       => 'StoreFileOp',
-			'copy'        => 'CopyFileOp',
-			'move'        => 'MoveFileOp',
-			'delete'      => 'DeleteFileOp',
-			'create'      => 'CreateFileOp',
-			'null'        => 'NullFileOp'
+			'store' => 'StoreFileOp',
+			'copy' => 'CopyFileOp',
+			'move' => 'MoveFileOp',
+			'delete' => 'DeleteFileOp',
+			'create' => 'CreateFileOp',
+			'describe' => 'DescribeFileOp',
+			'null' => 'NullFileOp'
 		);
 
 		$performOps = array(); // array of FileOp objects
@@ -947,11 +953,13 @@ abstract class FileBackendStore extends FileBackend {
 
 	/**
 	 * Get a list of storage paths to lock for a list of operations
-	 * Returns an array with 'sh' (shared) and 'ex' (exclusive) keys,
-	 * each corresponding to a list of storage paths to be locked.
+	 * Returns an array with LockManager::LOCK_UW (shared locks) and
+	 * LockManager::LOCK_EX (exclusive locks) keys, each corresponding
+	 * to a list of storage paths to be locked. All returned paths are
+	 * normalized.
 	 *
-	 * @param $performOps Array List of FileOp objects
-	 * @return Array ('sh' => list of paths, 'ex' => list of paths)
+	 * @param array $performOps List of FileOp objects
+	 * @return Array (LockManager::LOCK_UW => path list, LockManager::LOCK_EX => path list)
 	 */
 	final public function getPathsToLockForOpsInternal( array $performOps ) {
 		// Build up a list of files to lock...
@@ -965,30 +973,24 @@ abstract class FileBackendStore extends FileBackend {
 		// Get a shared lock on the parent directory of each path changed
 		$paths['sh'] = array_merge( $paths['sh'], array_map( 'dirname', $paths['ex'] ) );
 
-		return $paths;
+		return array(
+			LockManager::LOCK_UW => $paths['sh'],
+			LockManager::LOCK_EX => $paths['ex']
+		);
 	}
 
-	/**
-	 * @see FileBackend::getScopedLocksForOps()
-	 * @return Array
-	 */
 	public function getScopedLocksForOps( array $ops, Status $status ) {
 		$paths = $this->getPathsToLockForOpsInternal( $this->getOperationsInternal( $ops ) );
-		return array(
-			$this->getScopedFileLocks( $paths['sh'], LockManager::LOCK_UW, $status ),
-			$this->getScopedFileLocks( $paths['ex'], LockManager::LOCK_EX, $status )
-		);
+		return array( $this->getScopedFileLocks( $paths, 'mixed', $status ) );
 	}
 
-	/**
-	 * @see FileBackend::doOperationsInternal()
-	 * @return Status
-	 */
 	final protected function doOperationsInternal( array $ops, array $opts ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = Status::newGood();
 
+		// Fix up custom header name/value pairs...
+		$ops = array_map( array( $this, 'stripInvalidHeadersFromOp' ), $ops );
+
 		// Build up a list of FileOps...
 		$performOps = $this->getOperationsInternal( $ops );
 
@@ -997,11 +999,8 @@ abstract class FileBackendStore extends FileBackend {
 			// Build up a list of files to lock...
 			$paths = $this->getPathsToLockForOpsInternal( $performOps );
 			// Try to lock those files for the scope of this function...
-			$scopeLockS = $this->getScopedFileLocks( $paths['sh'], LockManager::LOCK_UW, $status );
-			$scopeLockE = $this->getScopedFileLocks( $paths['ex'], LockManager::LOCK_EX, $status );
+			$scopeLock = $this->getScopedFileLocks( $paths, 'mixed', $status );
 			if ( !$status->isOK() ) {
-				wfProfileOut( __METHOD__ . '-' . $this->name );
-				wfProfileOut( __METHOD__ );
 				return $status; // abort
 			}
 		}
@@ -1016,29 +1015,28 @@ abstract class FileBackendStore extends FileBackend {
 		$this->primeContainerCache( $performOps );
 
 		// Actually attempt the operation batch...
+		$opts = $this->setConcurrencyFlags( $opts );
 		$subStatus = FileOpBatch::attempt( $performOps, $opts, $this->fileJournal );
 
 		// Merge errors into status fields
 		$status->merge( $subStatus );
 		$status->success = $subStatus->success; // not done in merge()
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
-	/**
-	 * @see FileBackend::doQuickOperationsInternal()
-	 * @return Status
-	 * @throws MWException
-	 */
 	final protected function doQuickOperationsInternal( array $ops ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		$status = Status::newGood();
 
+		// Fix up custom header name/value pairs...
+		$ops = array_map( array( $this, 'stripInvalidHeadersFromOp' ), $ops );
+
+		// Clear any file cache entries
+		$this->clearCache();
+
 		$supportedOps = array( 'create', 'store', 'copy', 'move', 'delete', 'null' );
-		$async = ( $this->parallelize === 'implicit' );
+		$async = ( $this->parallelize === 'implicit' && count( $ops ) > 1 );
 		$maxConcurrency = $this->concurrency; // throttle
 
 		$statuses = array(); // array of (index => Status)
@@ -1047,8 +1045,6 @@ abstract class FileBackendStore extends FileBackend {
 		// Perform the sync-only ops and build up op handles for the async ops...
 		foreach ( $ops as $index => $params ) {
 			if ( !in_array( $params['op'], $supportedOps ) ) {
-				wfProfileOut( __METHOD__ . '-' . $this->name );
-				wfProfileOut( __METHOD__ );
 				throw new MWException( "Operation '{$params['op']}' is not supported." );
 			}
 			$method = $params['op'] . 'Internal'; // e.g. "storeInternal"
@@ -1082,8 +1078,6 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -1092,13 +1086,12 @@ abstract class FileBackendStore extends FileBackend {
 	 * The resulting Status object fields will correspond
 	 * to the order in which the handles where given.
 	 *
-	 * @param $handles Array List of FileBackendStoreOpHandle objects
+	 * @param array $handles List of FileBackendStoreOpHandle objects
 	 * @return Array Map of Status objects
 	 * @throws MWException
 	 */
 	final public function executeOpHandlesInternal( array $fileOpHandles ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 		foreach ( $fileOpHandles as $fileOpHandle ) {
 			if ( !( $fileOpHandle instanceof FileBackendStoreOpHandle ) ) {
 				throw new MWException( "Given a non-FileBackendStoreOpHandle object." );
@@ -1110,13 +1103,13 @@ abstract class FileBackendStore extends FileBackend {
 		foreach ( $fileOpHandles as $fileOpHandle ) {
 			$fileOpHandle->closeResources();
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $res;
 	}
 
 	/**
 	 * @see FileBackendStore::executeOpHandlesInternal()
+	 * @param array $fileOpHandles
+	 * @throws MWException
 	 * @return Array List of corresponding Status objects
 	 */
 	protected function doExecuteOpHandlesInternal( array $fileOpHandles ) {
@@ -1127,12 +1120,34 @@ abstract class FileBackendStore extends FileBackend {
 	}
 
 	/**
-	 * @see FileBackend::preloadCache()
+	 * Strip long HTTP headers from a file operation.
+	 * Most headers are just numbers, but some are allowed to be long.
+	 * This function is useful for cleaning up headers and avoiding backend
+	 * specific errors, especially in the middle of batch file operations.
+	 *
+	 * @param array $op Same format as doOperation()
+	 * @return Array
 	 */
+	protected function stripInvalidHeadersFromOp( array $op ) {
+		static $longs = array( 'Content-Disposition' );
+		if ( isset( $op['headers'] ) ) { // op sets HTTP headers
+			foreach ( $op['headers'] as $name => $value ) {
+				$maxHVLen = in_array( $name, $longs ) ? INF : 255;
+				if ( strlen( $name ) > 255 || strlen( $value ) > $maxHVLen ) {
+					trigger_error( "Header '$name: $value' is too long." );
+					unset( $op['headers'][$name] );
+				} elseif ( !strlen( $value ) ) {
+					$op['headers'][$name] = ''; // null/false => ""
+				}
+			}
+		}
+		return $op;
+	}
+
 	final public function preloadCache( array $paths ) {
 		$fullConts = array(); // full container names
 		foreach ( $paths as $path ) {
-			list( $fullCont, $r, $s ) = $this->resolveStoragePath( $path );
+			list( $fullCont, , ) = $this->resolveStoragePath( $path );
 			$fullConts[] = $fullCont;
 		}
 		// Load from the persistent file and container caches
@@ -1140,9 +1155,6 @@ abstract class FileBackendStore extends FileBackend {
 		$this->primeFileCache( $paths );
 	}
 
-	/**
-	 * @see FileBackend::clearCache()
-	 */
 	final public function clearCache( array $paths = null ) {
 		if ( is_array( $paths ) ) {
 			$paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
@@ -1165,7 +1177,7 @@ abstract class FileBackendStore extends FileBackend {
 	 *
 	 * @see FileBackend::clearCache()
 	 *
-	 * @param $paths Array Storage paths (optional)
+	 * @param array $paths Storage paths (optional)
 	 * @return void
 	 */
 	protected function doClearCache( array $paths = null ) {}
@@ -1183,7 +1195,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * Check if a container name is valid.
 	 * This checks for for length and illegal characters.
 	 *
-	 * @param $container string
+	 * @param string $container
 	 * @return bool
 	 */
 	final protected static function isValidContainerName( $container ) {
@@ -1205,7 +1217,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * this means that the path can only refer to a directory and can only
 	 * be scanned by looking in all the container shards.
 	 *
-	 * @param $storagePath string
+	 * @param string $storagePath
 	 * @return Array (container, path, container suffix) or (null, null, null) if invalid
 	 */
 	final protected function resolveStoragePath( $storagePath ) {
@@ -1235,16 +1247,22 @@ abstract class FileBackendStore extends FileBackend {
 
 	/**
 	 * Like resolveStoragePath() except null values are returned if
-	 * the container is sharded and the shard could not be determined.
+	 * the container is sharded and the shard could not be determined
+	 * or if the path ends with '/'. The later case is illegal for FS
+	 * backends and can confuse listings for object store backends.
+	 *
+	 * This function is used when resolving paths that must be valid
+	 * locations for files. Directory and listing functions should
+	 * generally just use resolveStoragePath() instead.
 	 *
 	 * @see FileBackendStore::resolveStoragePath()
 	 *
-	 * @param $storagePath string
+	 * @param string $storagePath
 	 * @return Array (container, path) or (null, null) if invalid
 	 */
 	final protected function resolveStoragePathReal( $storagePath ) {
 		list( $container, $relPath, $cShard ) = $this->resolveStoragePath( $storagePath );
-		if ( $cShard !== null ) {
+		if ( $cShard !== null && substr( $relPath, -1 ) !== '/' ) {
 			return array( $container, $relPath );
 		}
 		return array( null, null );
@@ -1254,8 +1272,8 @@ abstract class FileBackendStore extends FileBackend {
 	 * Get the container name shard suffix for a given path.
 	 * Any empty suffix means the container is not sharded.
 	 *
-	 * @param $container string Container name
-	 * @param $relPath string Storage path relative to the container
+	 * @param string $container Container name
+	 * @param string $relPath Storage path relative to the container
 	 * @return string|null Returns null if shard could not be determined
 	 */
 	final protected function getContainerShard( $container, $relPath ) {
@@ -1291,11 +1309,11 @@ abstract class FileBackendStore extends FileBackend {
 	 * Container dirs like "a", where the container shards on "x/xy",
 	 * can reside on several shards. Such paths are tricky to handle.
 	 *
-	 * @param $storagePath string Storage path
+	 * @param string $storagePath Storage path
 	 * @return bool
 	 */
 	final public function isSingleShardPathInternal( $storagePath ) {
-		list( $c, $r, $shard ) = $this->resolveStoragePath( $storagePath );
+		list( , , $shard ) = $this->resolveStoragePath( $storagePath );
 		return ( $shard !== null );
 	}
 
@@ -1304,7 +1322,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * If greater than 0, then all file storage paths within
 	 * the container are required to be hashed accordingly.
 	 *
-	 * @param $container string
+	 * @param string $container
 	 * @return Array (integer levels, integer base, repeat flag) or (0, 0, false)
 	 */
 	final protected function getContainerHashLevels( $container ) {
@@ -1324,7 +1342,7 @@ abstract class FileBackendStore extends FileBackend {
 	/**
 	 * Get a list of full container shard suffixes for a container
 	 *
-	 * @param $container string
+	 * @param string $container
 	 * @return Array
 	 */
 	final protected function getContainerSuffixes( $container ) {
@@ -1342,7 +1360,7 @@ abstract class FileBackendStore extends FileBackend {
 	/**
 	 * Get the full container name, including the wiki ID prefix
 	 *
-	 * @param $container string
+	 * @param string $container
 	 * @return string
 	 */
 	final protected function fullContainerName( $container ) {
@@ -1358,7 +1376,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * This is intended for internal use, such as encoding illegal chars.
 	 * Subclasses can override this to be more restrictive.
 	 *
-	 * @param $container string
+	 * @param string $container
 	 * @return string|null
 	 */
 	protected function resolveContainerName( $container ) {
@@ -1371,8 +1389,8 @@ abstract class FileBackendStore extends FileBackend {
 	 * getting absolute paths (e.g. FS based backends). Note that the relative path
 	 * may be the empty string (e.g. the path is simply to the container).
 	 *
-	 * @param $container string Container name
-	 * @param $relStoragePath string Storage path relative to the container
+	 * @param string $container Container name
+	 * @param string $relStoragePath Storage path relative to the container
 	 * @return string|null Path or null if not valid
 	 */
 	protected function resolveContainerPath( $container, $relStoragePath ) {
@@ -1382,7 +1400,7 @@ abstract class FileBackendStore extends FileBackend {
 	/**
 	 * Get the cache key for a container
 	 *
-	 * @param $container string Resolved container name
+	 * @param string $container Resolved container name
 	 * @return string
 	 */
 	private function containerCacheKey( $container ) {
@@ -1392,18 +1410,20 @@ abstract class FileBackendStore extends FileBackend {
 	/**
 	 * Set the cached info for a container
 	 *
-	 * @param $container string Resolved container name
-	 * @param $val mixed Information to cache
+	 * @param string $container Resolved container name
+	 * @param array $val Information to cache
+	 * @return void
 	 */
-	final protected function setContainerCache( $container, $val ) {
-		$this->memCache->add( $this->containerCacheKey( $container ), $val, 14*86400 );
+	final protected function setContainerCache( $container, array $val ) {
+		$this->memCache->add( $this->containerCacheKey( $container ), $val, 14 * 86400 );
 	}
 
 	/**
 	 * Delete the cached info for a container.
 	 * The cache key is salted for a while to prevent race conditions.
 	 *
-	 * @param $container string Resolved container name
+	 * @param string $container Resolved container name
+	 * @return void
 	 */
 	final protected function deleteContainerCache( $container ) {
 		if ( !$this->memCache->set( $this->containerCacheKey( $container ), 'PURGED', 300 ) ) {
@@ -1414,13 +1434,13 @@ abstract class FileBackendStore extends FileBackend {
 	/**
 	 * Do a batch lookup from cache for container stats for all containers
 	 * used in a list of container names, storage paths, or FileOp objects.
+	 * This loads the persistent cache values into the process cache.
 	 *
-	 * @param $items Array
+	 * @param Array $items
 	 * @return void
 	 */
 	final protected function primeContainerCache( array $items ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 
 		$paths = array(); // list of storage paths
 		$contNames = array(); // (cache key => resolved container name)
@@ -1437,7 +1457,7 @@ abstract class FileBackendStore extends FileBackend {
 		}
 		// Get all the corresponding cache keys for paths...
 		foreach ( $paths as $path ) {
-			list( $fullCont, $r, $s ) = $this->resolveStoragePath( $path );
+			list( $fullCont, , ) = $this->resolveStoragePath( $path );
 			if ( $fullCont !== null ) { // valid path for this backend
 				$contNames[$this->containerCacheKey( $fullCont )] = $fullCont;
 			}
@@ -1452,9 +1472,6 @@ abstract class FileBackendStore extends FileBackend {
 
 		// Populate the container process cache for the backend...
 		$this->doPrimeContainerCache( array_filter( $contInfo, 'is_array' ) );
-
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 	}
 
 	/**
@@ -1462,7 +1479,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * resolved container names and their corresponding cached info.
 	 * Only containers that actually exist should appear in the map.
 	 *
-	 * @param $containerInfo Array Map of resolved container names to cached info
+	 * @param array $containerInfo Map of resolved container names to cached info
 	 * @return void
 	 */
 	protected function doPrimeContainerCache( array $containerInfo ) {}
@@ -1470,7 +1487,7 @@ abstract class FileBackendStore extends FileBackend {
 	/**
 	 * Get the cache key for a file path
 	 *
-	 * @param $path string Storage path
+	 * @param string $path Normalized storage path
 	 * @return string
 	 */
 	private function fileCacheKey( $path ) {
@@ -1482,20 +1499,34 @@ abstract class FileBackendStore extends FileBackend {
 	 * Negatives (404s) are not cached. By not caching negatives, we can skip cache
 	 * salting for the case when a file is created at a path were there was none before.
 	 *
-	 * @param $path string Storage path
-	 * @param $val mixed Information to cache
+	 * @param string $path Storage path
+	 * @param array $val Stat information to cache
+	 * @return void
 	 */
-	final protected function setFileCache( $path, $val ) {
-		$this->memCache->add( $this->fileCacheKey( $path ), $val, 7*86400 );
+	final protected function setFileCache( $path, array $val ) {
+		$path = FileBackend::normalizeStoragePath( $path );
+		if ( $path === null ) {
+			return; // invalid storage path
+		}
+		$age = time() - wfTimestamp( TS_UNIX, $val['mtime'] );
+		$ttl = min( 7 * 86400, max( 300, floor( .1 * $age ) ) );
+		$this->memCache->add( $this->fileCacheKey( $path ), $val, $ttl );
 	}
 
 	/**
 	 * Delete the cached stat info for a file path.
 	 * The cache key is salted for a while to prevent race conditions.
+	 * Since negatives (404s) are not cached, this does not need to be called when
+	 * a file is created at a path were there was none before.
 	 *
-	 * @param $path string Storage path
+	 * @param string $path Storage path
+	 * @return void
 	 */
 	final protected function deleteFileCache( $path ) {
+		$path = FileBackend::normalizeStoragePath( $path );
+		if ( $path === null ) {
+			return; // invalid storage path
+		}
 		if ( !$this->memCache->set( $this->fileCacheKey( $path ), 'PURGED', 300 ) ) {
 			trigger_error( "Unable to delete stat cache for file $path." );
 		}
@@ -1504,13 +1535,13 @@ abstract class FileBackendStore extends FileBackend {
 	/**
 	 * Do a batch lookup from cache for file stats for all paths
 	 * used in a list of storage paths or FileOp objects.
+	 * This loads the persistent cache values into the process cache.
 	 *
-	 * @param $items Array List of storage paths or FileOps
+	 * @param array $items List of storage paths or FileOps
 	 * @return void
 	 */
 	final protected function primeFileCache( array $items ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 
 		$paths = array(); // list of storage paths
 		$pathNames = array(); // (cache key => storage path)
@@ -1520,12 +1551,14 @@ abstract class FileBackendStore extends FileBackend {
 				$paths = array_merge( $paths, $item->storagePathsRead() );
 				$paths = array_merge( $paths, $item->storagePathsChanged() );
 			} elseif ( self::isStoragePath( $item ) ) {
-				$paths[] = $item;
+				$paths[] = FileBackend::normalizeStoragePath( $item );
 			}
 		}
+		// Get rid of any paths that failed normalization...
+		$paths = array_filter( $paths, 'strlen' ); // remove nulls
 		// Get all the corresponding cache keys for paths...
 		foreach ( $paths as $path ) {
-			list( $cont, $rel, $s ) = $this->resolveStoragePath( $path );
+			list( , $rel, ) = $this->resolveStoragePath( $path );
 			if ( $rel !== null ) { // valid path for this backend
 				$pathNames[$this->fileCacheKey( $path )] = $path;
 			}
@@ -1542,9 +1575,38 @@ abstract class FileBackendStore extends FileBackend {
 				}
 			}
 		}
+	}
+
+	/**
+	 * Set the 'concurrency' option from a list of operation options
+	 *
+	 * @param array $opts Map of operation options
+	 * @return Array
+	 */
+	final protected function setConcurrencyFlags( array $opts ) {
+		$opts['concurrency'] = 1; // off
+		if ( $this->parallelize === 'implicit' ) {
+			if ( !isset( $opts['parallelize'] ) || $opts['parallelize'] ) {
+				$opts['concurrency'] = $this->concurrency;
+			}
+		} elseif ( $this->parallelize === 'explicit' ) {
+			if ( !empty( $opts['parallelize'] ) ) {
+				$opts['concurrency'] = $this->concurrency;
+			}
+		}
+		return $opts;
+	}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
+	/**
+	 * Get the content type to use in HEAD/GET requests for a file
+	 *
+	 * @param string $storagePath
+	 * @param string|null $content File data
+	 * @param string|null $fsPath File system path
+	 * @return MIME type
+	 */
+	protected function getContentType( $storagePath, $content, $fsPath ) {
+		return call_user_func_array( $this->mimeCallback, func_get_args() );
 	}
 }
 
@@ -1582,30 +1644,24 @@ abstract class FileBackendStoreOpHandle {
  *
  * @ingroup FileBackend
  */
-abstract class FileBackendStoreShardListIterator implements Iterator {
+abstract class FileBackendStoreShardListIterator extends FilterIterator {
 	/** @var FileBackendStore */
 	protected $backend;
 	/** @var Array */
 	protected $params;
-	/** @var Array */
-	protected $shardSuffixes;
+
 	protected $container; // string; full container name
 	protected $directory; // string; resolved relative path
 
-	/** @var Traversable */
-	protected $iter;
-	protected $curShard = 0; // integer
-	protected $pos = 0; // integer
-
 	/** @var Array */
 	protected $multiShardPaths = array(); // (rel path => 1)
 
 	/**
-	 * @param $backend FileBackendStore
-	 * @param $container string Full storage container name
-	 * @param $dir string Storage directory relative to container
-	 * @param $suffixes Array List of container shard suffixes
-	 * @param $params Array
+	 * @param FileBackendStore $backend
+	 * @param string $container Full storage container name
+	 * @param string $dir Storage directory relative to container
+	 * @param array $suffixes List of container shard suffixes
+	 * @param array $params
 	 */
 	public function __construct(
 		FileBackendStore $backend, $container, $dir, array $suffixes, array $params
@@ -1613,142 +1669,56 @@ abstract class FileBackendStoreShardListIterator implements Iterator {
 		$this->backend = $backend;
 		$this->container = $container;
 		$this->directory = $dir;
-		$this->shardSuffixes = $suffixes;
 		$this->params = $params;
-	}
-
-	/**
-	 * @see Iterator::key()
-	 * @return integer
-	 */
-	public function key() {
-		return $this->pos;
-	}
 
-	/**
-	 * @see Iterator::valid()
-	 * @return bool
-	 */
-	public function valid() {
-		if ( $this->iter instanceof Iterator ) {
-			return $this->iter->valid();
-		} elseif ( is_array( $this->iter ) ) {
-			return ( current( $this->iter ) !== false ); // no paths can have this value
+		$iter = new AppendIterator();
+		foreach ( $suffixes as $suffix ) {
+			$iter->append( $this->listFromShard( $this->container . $suffix ) );
 		}
-		return false; // some failure?
-	}
 
-	/**
-	 * @see Iterator::current()
-	 * @return string|bool String or false
-	 */
-	public function current() {
-		return ( $this->iter instanceof Iterator )
-			? $this->iter->current()
-			: current( $this->iter );
+		parent::__construct( $iter );
 	}
 
-	/**
-	 * @see Iterator::next()
-	 * @return void
-	 */
-	public function next() {
-		++$this->pos;
-		( $this->iter instanceof Iterator ) ? $this->iter->next() : next( $this->iter );
-		do {
-			$continue = false; // keep scanning shards?
-			$this->filterViaNext(); // filter out duplicates
-			// Find the next non-empty shard if no elements are left
-			if ( !$this->valid() ) {
-				$this->nextShardIteratorIfNotValid();
-				$continue = $this->valid(); // re-filter unless we ran out of shards
-			}
-		} while ( $continue );
-	}
-
-	/**
-	 * @see Iterator::rewind()
-	 * @return void
-	 */
-	public function rewind() {
-		$this->pos = 0;
-		$this->curShard = 0;
-		$this->setIteratorFromCurrentShard();
-		do {
-			$continue = false; // keep scanning shards?
-			$this->filterViaNext(); // filter out duplicates
-			// Find the next non-empty shard if no elements are left
-			if ( !$this->valid() ) {
-				$this->nextShardIteratorIfNotValid();
-				$continue = $this->valid(); // re-filter unless we ran out of shards
-			}
-		} while ( $continue );
-	}
-
-	/**
-	 * Filter out duplicate items by advancing to the next ones
-	 */
-	protected function filterViaNext() {
-		while ( $this->valid() ) {
-			$rel = $this->iter->current(); // path relative to given directory
-			$path = $this->params['dir'] . "/{$rel}"; // full storage path
-			if ( $this->backend->isSingleShardPathInternal( $path ) ) {
-				break; // path is only on one shard; no issue with duplicates
-			} elseif ( isset( $this->multiShardPaths[$rel] ) ) {
-				// Don't keep listing paths that are on multiple shards
-				( $this->iter instanceof Iterator ) ? $this->iter->next() : next( $this->iter );
-			} else {
-				$this->multiShardPaths[$rel] = 1;
-				break;
-			}
-		}
-	}
-
-	/**
-	 * If the list iterator for this container shard is out of items,
-	 * then move on to the next container that has items.
-	 * If there are none, then it advances to the last container.
-	 */
-	protected function nextShardIteratorIfNotValid() {
-		while ( !$this->valid() && ++$this->curShard < count( $this->shardSuffixes ) ) {
-			$this->setIteratorFromCurrentShard();
+	public function accept() {
+		$rel = $this->getInnerIterator()->current(); // path relative to given directory
+		$path = $this->params['dir'] . "/{$rel}"; // full storage path
+		if ( $this->backend->isSingleShardPathInternal( $path ) ) {
+			return true; // path is only on one shard; no issue with duplicates
+		} elseif ( isset( $this->multiShardPaths[$rel] ) ) {
+			// Don't keep listing paths that are on multiple shards
+			return false;
+		} else {
+			$this->multiShardPaths[$rel] = 1;
+			return true;
 		}
 	}
 
-	/**
-	 * Set the list iterator to that of the current container shard
-	 */
-	protected function setIteratorFromCurrentShard() {
-		$this->iter = $this->listFromShard(
-			$this->container . $this->shardSuffixes[$this->curShard],
-			$this->directory, $this->params );
-		// Start loading results so that current() works
-		if ( $this->iter ) {
-			( $this->iter instanceof Iterator ) ? $this->iter->rewind() : reset( $this->iter );
-		}
+	public function rewind() {
+		parent::rewind();
+		$this->multiShardPaths = array();
 	}
 
 	/**
 	 * Get the list for a given container shard
 	 *
-	 * @param $container string Resolved container name
-	 * @param $dir string Resolved path relative to container
-	 * @param $params Array
-	 * @return Traversable|Array|null
+	 * @param string $container Resolved container name
+	 * @return Iterator
 	 */
-	abstract protected function listFromShard( $container, $dir, array $params );
+	abstract protected function listFromShard( $container );
 }
 
 /**
  * Iterator for listing directories
  */
 class FileBackendStoreShardDirIterator extends FileBackendStoreShardListIterator {
-	/**
-	 * @see FileBackendStoreShardListIterator::listFromShard()
-	 * @return Array|null|Traversable
-	 */
-	protected function listFromShard( $container, $dir, array $params ) {
-		return $this->backend->getDirectoryListInternal( $container, $dir, $params );
+	protected function listFromShard( $container ) {
+		$list = $this->backend->getDirectoryListInternal(
+			$container, $this->directory, $this->params );
+		if ( $list === null ) {
+			return new ArrayIterator( array() );
+		} else {
+			return is_array( $list ) ? new ArrayIterator( $list ) : $list;
+		}
 	}
 }
 
@@ -1756,11 +1726,13 @@ class FileBackendStoreShardDirIterator extends FileBackendStoreShardListIterator
  * Iterator for listing regular files
  */
 class FileBackendStoreShardFileIterator extends FileBackendStoreShardListIterator {
-	/**
-	 * @see FileBackendStoreShardListIterator::listFromShard()
-	 * @return Array|null|Traversable
-	 */
-	protected function listFromShard( $container, $dir, array $params ) {
-		return $this->backend->getFileListInternal( $container, $dir, $params );
+	protected function listFromShard( $container ) {
+		$list = $this->backend->getFileListInternal(
+			$container, $this->directory, $this->params );
+		if ( $list === null ) {
+			return new ArrayIterator( array() );
+		} else {
+			return is_array( $list ) ? new ArrayIterator( $list ) : $list;
+		}
 	}
 }
diff --git a/includes/filebackend/FileOp.php b/includes/filebackend/FileOp.php
index 7c43c489..fe833084 100644
--- a/includes/filebackend/FileOp.php
+++ b/includes/filebackend/FileOp.php
@@ -42,11 +42,12 @@ abstract class FileOp {
 	protected $state = self::STATE_NEW; // integer
 	protected $failed = false; // boolean
 	protected $async = false; // boolean
-	protected $useLatest = true; // boolean
 	protected $batchId; // string
 
+	protected $doOperation = true; // boolean; operation is not a no-op
 	protected $sourceSha1; // string
-	protected $destSameAsSource; // boolean
+	protected $overwriteSameCase; // boolean
+	protected $destExists; // boolean
 
 	/* Object life-cycle */
 	const STATE_NEW = 1;
@@ -54,54 +55,81 @@ abstract class FileOp {
 	const STATE_ATTEMPTED = 3;
 
 	/**
-	 * Build a new file operation transaction
+	 * Build a new batch file operation transaction
 	 *
-	 * @param $backend FileBackendStore
-	 * @param $params Array
+	 * @param FileBackendStore $backend
+	 * @param Array $params
 	 * @throws MWException
 	 */
 	final public function __construct( FileBackendStore $backend, array $params ) {
 		$this->backend = $backend;
 		list( $required, $optional ) = $this->allowedParams();
+		// @todo normalizeAnyStoragePaths() calls are overzealous, use a parameter list
 		foreach ( $required as $name ) {
 			if ( isset( $params[$name] ) ) {
-				$this->params[$name] = $params[$name];
+				// Normalize paths so the paths to the same file have the same string
+				$this->params[$name] = self::normalizeAnyStoragePaths( $params[$name] );
 			} else {
 				throw new MWException( "File operation missing parameter '$name'." );
 			}
 		}
 		foreach ( $optional as $name ) {
 			if ( isset( $params[$name] ) ) {
-				$this->params[$name] = $params[$name];
+				// Normalize paths so the paths to the same file have the same string
+				$this->params[$name] = self::normalizeAnyStoragePaths( $params[$name] );
 			}
 		}
 		$this->params = $params;
 	}
 
 	/**
-	 * Set the batch UUID this operation belongs to
+	 * Normalize $item or anything in $item that is a valid storage path
 	 *
-	 * @param $batchId string
-	 * @return void
+	 * @param string $item|array
+	 * @return string|Array
+	 */
+	protected function normalizeAnyStoragePaths( $item ) {
+		if ( is_array( $item ) ) {
+			$res = array();
+			foreach ( $item as $k => $v ) {
+				$k = self::normalizeIfValidStoragePath( $k );
+				$v = self::normalizeIfValidStoragePath( $v );
+				$res[$k] = $v;
+			}
+			return $res;
+		} else {
+			return self::normalizeIfValidStoragePath( $item );
+		}
+	}
+
+	/**
+	 * Normalize a string if it is a valid storage path
+	 *
+	 * @param string $path
+	 * @return string
 	 */
-	final public function setBatchId( $batchId ) {
-		$this->batchId = $batchId;
+	protected static function normalizeIfValidStoragePath( $path ) {
+		if ( FileBackend::isStoragePath( $path ) ) {
+			$res = FileBackend::normalizeStoragePath( $path );
+			return ( $res !== null ) ? $res : $path;
+		}
+		return $path;
 	}
 
 	/**
-	 * Whether to allow stale data for file reads and stat checks
+	 * Set the batch UUID this operation belongs to
 	 *
-	 * @param $allowStale bool
+	 * @param string $batchId
 	 * @return void
 	 */
-	final public function allowStaleReads( $allowStale ) {
-		$this->useLatest = !$allowStale;
+	final public function setBatchId( $batchId ) {
+		$this->batchId = $batchId;
 	}
 
 	/**
 	 * Get the value of the parameter with the given name
 	 *
-	 * @param $name string
+	 * @param string $name
 	 * @return mixed Returns null if the parameter is not set
 	 */
 	final public function getParam( $name ) {
@@ -138,11 +166,11 @@ abstract class FileOp {
 	/**
 	 * Update a dependency tracking array to account for this operation
 	 *
-	 * @param $deps Array Prior path reads/writes; format of FileOp::newPredicates()
+	 * @param array $deps Prior path reads/writes; format of FileOp::newPredicates()
 	 * @return Array
 	 */
 	final public function applyDependencies( array $deps ) {
-		$deps['read']  += array_fill_keys( $this->storagePathsRead(), 1 );
+		$deps['read'] += array_fill_keys( $this->storagePathsRead(), 1 );
 		$deps['write'] += array_fill_keys( $this->storagePathsChanged(), 1 );
 		return $deps;
 	}
@@ -150,7 +178,7 @@ abstract class FileOp {
 	/**
 	 * Check if this operation changes files listed in $paths
 	 *
-	 * @param $paths Array Prior path reads/writes; format of FileOp::newPredicates()
+	 * @param array $paths Prior path reads/writes; format of FileOp::newPredicates()
 	 * @return boolean
 	 */
 	final public function dependsOn( array $deps ) {
@@ -170,33 +198,36 @@ abstract class FileOp {
 	/**
 	 * Get the file journal entries for this file operation
 	 *
-	 * @param $oPredicates Array Pre-op info about files (format of FileOp::newPredicates)
-	 * @param $nPredicates Array Post-op info about files (format of FileOp::newPredicates)
+	 * @param array $oPredicates Pre-op info about files (format of FileOp::newPredicates)
+	 * @param array $nPredicates Post-op info about files (format of FileOp::newPredicates)
 	 * @return Array
 	 */
 	final public function getJournalEntries( array $oPredicates, array $nPredicates ) {
+		if ( !$this->doOperation ) {
+			return array(); // this is a no-op
+		}
 		$nullEntries = array();
 		$updateEntries = array();
 		$deleteEntries = array();
 		$pathsUsed = array_merge( $this->storagePathsRead(), $this->storagePathsChanged() );
-		foreach ( $pathsUsed as $path ) {
+		foreach ( array_unique( $pathsUsed ) as $path ) {
 			$nullEntries[] = array( // assertion for recovery
-				'op'      => 'null',
-				'path'    => $path,
+				'op' => 'null',
+				'path' => $path,
 				'newSha1' => $this->fileSha1( $path, $oPredicates )
 			);
 		}
 		foreach ( $this->storagePathsChanged() as $path ) {
 			if ( $nPredicates['sha1'][$path] === false ) { // deleted
 				$deleteEntries[] = array(
-					'op'      => 'delete',
-					'path'    => $path,
+					'op' => 'delete',
+					'path' => $path,
 					'newSha1' => ''
 				);
 			} else { // created/updated
 				$updateEntries[] = array(
-					'op'      => $this->fileExists( $path, $oPredicates ) ? 'update' : 'create',
-					'path'    => $path,
+					'op' => $this->fileExists( $path, $oPredicates ) ? 'update' : 'create',
+					'path' => $path,
 					'newSha1' => $nPredicates['sha1'][$path]
 				);
 			}
@@ -205,9 +236,11 @@ abstract class FileOp {
 	}
 
 	/**
-	 * Check preconditions of the operation without writing anything
+	 * Check preconditions of the operation without writing anything.
+	 * This must update $predicates for each path that the op can change
+	 * except when a failing status object is returned.
 	 *
-	 * @param $predicates Array
+	 * @param Array $predicates
 	 * @return Status
 	 */
 	final public function precheck( array &$predicates ) {
@@ -241,10 +274,14 @@ abstract class FileOp {
 			return Status::newFatal( 'fileop-fail-attempt-precheck' );
 		}
 		$this->state = self::STATE_ATTEMPTED;
-		$status = $this->doAttempt();
-		if ( !$status->isOK() ) {
-			$this->failed = true;
-			$this->logFailure( 'attempt' );
+		if ( $this->doOperation ) {
+			$status = $this->doAttempt();
+			if ( !$status->isOK() ) {
+				$this->failed = true;
+				$this->logFailure( 'attempt' );
+			}
+		} else { // no-op
+			$status = Status::newGood();
 		}
 		return $status;
 	}
@@ -280,7 +317,7 @@ abstract class FileOp {
 	/**
 	 * Adjust params to FileBackendStore internal file calls
 	 *
-	 * @param $params Array
+	 * @param Array $params
 	 * @return Array (required params list, optional params list)
 	 */
 	protected function setFlags( array $params ) {
@@ -292,15 +329,7 @@ abstract class FileOp {
 	 *
 	 * @return Array
 	 */
-	final public function storagePathsRead() {
-		return array_map( 'FileBackend::normalizeStoragePath', $this->doStoragePathsRead() );
-	}
-
-	/**
-	 * @see FileOp::storagePathsRead()
-	 * @return Array
-	 */
-	protected function doStoragePathsRead() {
+	public function storagePathsRead() {
 		return array();
 	}
 
@@ -309,24 +338,16 @@ abstract class FileOp {
 	 *
 	 * @return Array
 	 */
-	final public function storagePathsChanged() {
-		return array_map( 'FileBackend::normalizeStoragePath', $this->doStoragePathsChanged() );
-	}
-
-	/**
-	 * @see FileOp::storagePathsChanged()
-	 * @return Array
-	 */
-	protected function doStoragePathsChanged() {
+	public function storagePathsChanged() {
 		return array();
 	}
 
 	/**
 	 * Check for errors with regards to the destination file already existing.
-	 * This also updates the destSameAsSource and sourceSha1 member variables.
+	 * Also set the destExists, overwriteSameCase and sourceSha1 member variables.
 	 * A bad status will be returned if there is no chance it can be overwritten.
 	 *
-	 * @param $predicates Array
+	 * @param Array $predicates
 	 * @return Status
 	 */
 	protected function precheckDestExistence( array $predicates ) {
@@ -336,8 +357,9 @@ abstract class FileOp {
 		if ( $this->sourceSha1 === null ) { // file in storage?
 			$this->sourceSha1 = $this->fileSha1( $this->params['src'], $predicates );
 		}
-		$this->destSameAsSource = false;
-		if ( $this->fileExists( $this->params['dst'], $predicates ) ) {
+		$this->overwriteSameCase = false;
+		$this->destExists = $this->fileExists( $this->params['dst'], $predicates );
+		if ( $this->destExists ) {
 			if ( $this->getParam( 'overwrite' ) ) {
 				return $status; // OK
 			} elseif ( $this->getParam( 'overwriteSame' ) ) {
@@ -349,7 +371,7 @@ abstract class FileOp {
 					// Give an error if the files are not identical
 					$status->fatal( 'backend-fail-notsame', $this->params['dst'] );
 				} else {
-					$this->destSameAsSource = true; // OK
+					$this->overwriteSameCase = true; // OK
 				}
 				return $status; // do nothing; either OK or bad status
 			} else {
@@ -362,7 +384,7 @@ abstract class FileOp {
 
 	/**
 	 * precheckDestExistence() helper function to get the source file SHA-1.
-	 * Subclasses should overwride this iff the source is not in storage.
+	 * Subclasses should overwride this if the source is not in storage.
 	 *
 	 * @return string|bool Returns false on failure
 	 */
@@ -373,15 +395,15 @@ abstract class FileOp {
 	/**
 	 * Check if a file will exist in storage when this operation is attempted
 	 *
-	 * @param $source string Storage path
-	 * @param $predicates Array
+	 * @param string $source Storage path
+	 * @param Array $predicates
 	 * @return bool
 	 */
 	final protected function fileExists( $source, array $predicates ) {
 		if ( isset( $predicates['exists'][$source] ) ) {
 			return $predicates['exists'][$source]; // previous op assures this
 		} else {
-			$params = array( 'src' => $source, 'latest' => $this->useLatest );
+			$params = array( 'src' => $source, 'latest' => true );
 			return $this->backend->fileExists( $params );
 		}
 	}
@@ -389,15 +411,17 @@ abstract class FileOp {
 	/**
 	 * Get the SHA-1 of a file in storage when this operation is attempted
 	 *
-	 * @param $source string Storage path
-	 * @param $predicates Array
+	 * @param string $source Storage path
+	 * @param Array $predicates
 	 * @return string|bool False on failure
 	 */
 	final protected function fileSha1( $source, array $predicates ) {
 		if ( isset( $predicates['sha1'][$source] ) ) {
 			return $predicates['sha1'][$source]; // previous op assures this
+		} elseif ( isset( $predicates['exists'][$source] ) && !$predicates['exists'][$source] ) {
+			return false; // previous op assures this
 		} else {
-			$params = array( 'src' => $source, 'latest' => $this->useLatest );
+			$params = array( 'src' => $source, 'latest' => true );
 			return $this->backend->getFileSha1Base36( $params );
 		}
 	}
@@ -414,7 +438,7 @@ abstract class FileOp {
 	/**
 	 * Log a file operation failure and preserve any temp files
 	 *
-	 * @param $action string
+	 * @param string $action
 	 * @return void
 	 */
 	final public function logFailure( $action ) {
@@ -430,42 +454,32 @@ abstract class FileOp {
 }
 
 /**
- * Store a file into the backend from a file on the file system.
+ * Create a file in the backend with the given content.
  * Parameters for this operation are outlined in FileBackend::doOperations().
  */
-class StoreFileOp extends FileOp {
-	/**
-	 * @return array
-	 */
+class CreateFileOp extends FileOp {
 	protected function allowedParams() {
-		return array( array( 'src', 'dst' ),
-			array( 'overwrite', 'overwriteSame', 'disposition' ) );
+		return array( array( 'content', 'dst' ),
+			array( 'overwrite', 'overwriteSame', 'headers' ) );
 	}
 
-	/**
-	 * @param $predicates array
-	 * @return Status
-	 */
 	protected function doPrecheck( array &$predicates ) {
 		$status = Status::newGood();
-		// Check if the source file exists on the file system
-		if ( !is_file( $this->params['src'] ) ) {
-			$status->fatal( 'backend-fail-notexists', $this->params['src'] );
-			return $status;
-		// Check if the source file is too big
-		} elseif ( filesize( $this->params['src'] ) > $this->backend->maxFileSizeInternal() ) {
+		// Check if the source data is too big
+		if ( strlen( $this->getParam( 'content' ) ) > $this->backend->maxFileSizeInternal() ) {
 			$status->fatal( 'backend-fail-maxsize',
 				$this->params['dst'], $this->backend->maxFileSizeInternal() );
-			$status->fatal( 'backend-fail-store', $this->params['src'], $this->params['dst'] );
+			$status->fatal( 'backend-fail-create', $this->params['dst'] );
 			return $status;
-		// Check if a file can be placed at the destination
+		// Check if a file can be placed/changed at the destination
 		} elseif ( !$this->backend->isPathUsableInternal( $this->params['dst'] ) ) {
 			$status->fatal( 'backend-fail-usable', $this->params['dst'] );
-			$status->fatal( 'backend-fail-store', $this->params['src'], $this->params['dst'] );
+			$status->fatal( 'backend-fail-create', $this->params['dst'] );
 			return $status;
 		}
 		// Check if destination file exists
 		$status->merge( $this->precheckDestExistence( $predicates ) );
+		$this->params['dstExists'] = $this->destExists; // see FileBackendStore::setFileCache()
 		if ( $status->isOK() ) {
 			// Update file existence predicates
 			$predicates['exists'][$this->params['dst']] = true;
@@ -474,61 +488,54 @@ class StoreFileOp extends FileOp {
 		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return Status
-	 */
 	protected function doAttempt() {
-		// Store the file at the destination
-		if ( !$this->destSameAsSource ) {
-			return $this->backend->storeInternal( $this->setFlags( $this->params ) );
+		if ( !$this->overwriteSameCase ) {
+			// Create the file at the destination
+			return $this->backend->createInternal( $this->setFlags( $this->params ) );
 		}
 		return Status::newGood();
 	}
 
-	/**
-	 * @return bool|string
-	 */
 	protected function getSourceSha1Base36() {
-		wfSuppressWarnings();
-		$hash = sha1_file( $this->params['src'] );
-		wfRestoreWarnings();
-		if ( $hash !== false ) {
-			$hash = wfBaseConvert( $hash, 16, 36, 31 );
-		}
-		return $hash;
+		return wfBaseConvert( sha1( $this->params['content'] ), 16, 36, 31 );
 	}
 
-	protected function doStoragePathsChanged() {
+	public function storagePathsChanged() {
 		return array( $this->params['dst'] );
 	}
 }
 
 /**
- * Create a file in the backend with the given content.
+ * Store a file into the backend from a file on the file system.
  * Parameters for this operation are outlined in FileBackend::doOperations().
  */
-class CreateFileOp extends FileOp {
+class StoreFileOp extends FileOp {
 	protected function allowedParams() {
-		return array( array( 'content', 'dst' ),
-			array( 'overwrite', 'overwriteSame', 'disposition' ) );
+		return array( array( 'src', 'dst' ),
+			array( 'overwrite', 'overwriteSame', 'headers' ) );
 	}
 
 	protected function doPrecheck( array &$predicates ) {
 		$status = Status::newGood();
-		// Check if the source data is too big
-		if ( strlen( $this->getParam( 'content' ) ) > $this->backend->maxFileSizeInternal() ) {
+		// Check if the source file exists on the file system
+		if ( !is_file( $this->params['src'] ) ) {
+			$status->fatal( 'backend-fail-notexists', $this->params['src'] );
+			return $status;
+		// Check if the source file is too big
+		} elseif ( filesize( $this->params['src'] ) > $this->backend->maxFileSizeInternal() ) {
 			$status->fatal( 'backend-fail-maxsize',
 				$this->params['dst'], $this->backend->maxFileSizeInternal() );
-			$status->fatal( 'backend-fail-create', $this->params['dst'] );
+			$status->fatal( 'backend-fail-store', $this->params['src'], $this->params['dst'] );
 			return $status;
-		// Check if a file can be placed at the destination
+		// Check if a file can be placed/changed at the destination
 		} elseif ( !$this->backend->isPathUsableInternal( $this->params['dst'] ) ) {
 			$status->fatal( 'backend-fail-usable', $this->params['dst'] );
-			$status->fatal( 'backend-fail-create', $this->params['dst'] );
+			$status->fatal( 'backend-fail-store', $this->params['src'], $this->params['dst'] );
 			return $status;
 		}
 		// Check if destination file exists
 		$status->merge( $this->precheckDestExistence( $predicates ) );
+		$this->params['dstExists'] = $this->destExists; // see FileBackendStore::setFileCache()
 		if ( $status->isOK() ) {
 			// Update file existence predicates
 			$predicates['exists'][$this->params['dst']] = true;
@@ -537,28 +544,25 @@ class CreateFileOp extends FileOp {
 		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return Status
-	 */
 	protected function doAttempt() {
-		if ( !$this->destSameAsSource ) {
-			// Create the file at the destination
-			return $this->backend->createInternal( $this->setFlags( $this->params ) );
+		if ( !$this->overwriteSameCase ) {
+			// Store the file at the destination
+			return $this->backend->storeInternal( $this->setFlags( $this->params ) );
 		}
 		return Status::newGood();
 	}
 
-	/**
-	 * @return bool|String
-	 */
 	protected function getSourceSha1Base36() {
-		return wfBaseConvert( sha1( $this->params['content'] ), 16, 36, 31 );
+		wfSuppressWarnings();
+		$hash = sha1_file( $this->params['src'] );
+		wfRestoreWarnings();
+		if ( $hash !== false ) {
+			$hash = wfBaseConvert( $hash, 16, 36, 31 );
+		}
+		return $hash;
 	}
 
-	/**
-	 * @return array
-	 */
-	protected function doStoragePathsChanged() {
+	public function storagePathsChanged() {
 		return array( $this->params['dst'] );
 	}
 }
@@ -568,25 +572,26 @@ class CreateFileOp extends FileOp {
  * Parameters for this operation are outlined in FileBackend::doOperations().
  */
 class CopyFileOp extends FileOp {
-	/**
-	 * @return array
-	 */
 	protected function allowedParams() {
 		return array( array( 'src', 'dst' ),
-			array( 'overwrite', 'overwriteSame', 'disposition' ) );
+			array( 'overwrite', 'overwriteSame', 'ignoreMissingSource', 'headers' ) );
 	}
 
-	/**
-	 * @param $predicates array
-	 * @return Status
-	 */
 	protected function doPrecheck( array &$predicates ) {
 		$status = Status::newGood();
 		// Check if the source file exists
 		if ( !$this->fileExists( $this->params['src'], $predicates ) ) {
-			$status->fatal( 'backend-fail-notexists', $this->params['src'] );
-			return $status;
-		// Check if a file can be placed at the destination
+			if ( $this->getParam( 'ignoreMissingSource' ) ) {
+				$this->doOperation = false; // no-op
+				// Update file existence predicates (cache 404s)
+				$predicates['exists'][$this->params['src']] = false;
+				$predicates['sha1'][$this->params['src']] = false;
+				return $status; // nothing to do
+			} else {
+				$status->fatal( 'backend-fail-notexists', $this->params['src'] );
+				return $status;
+			}
+		// Check if a file can be placed/changed at the destination
 		} elseif ( !$this->backend->isPathUsableInternal( $this->params['dst'] ) ) {
 			$status->fatal( 'backend-fail-usable', $this->params['dst'] );
 			$status->fatal( 'backend-fail-copy', $this->params['src'], $this->params['dst'] );
@@ -594,6 +599,7 @@ class CopyFileOp extends FileOp {
 		}
 		// Check if destination file exists
 		$status->merge( $this->precheckDestExistence( $predicates ) );
+		$this->params['dstExists'] = $this->destExists; // see FileBackendStore::setFileCache()
 		if ( $status->isOK() ) {
 			// Update file existence predicates
 			$predicates['exists'][$this->params['dst']] = true;
@@ -602,31 +608,27 @@ class CopyFileOp extends FileOp {
 		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return Status
-	 */
 	protected function doAttempt() {
-		// Do nothing if the src/dst paths are the same
-		if ( $this->params['src'] !== $this->params['dst'] ) {
-			// Copy the file into the destination
-			if ( !$this->destSameAsSource ) {
-				return $this->backend->copyInternal( $this->setFlags( $this->params ) );
-			}
+		if ( $this->overwriteSameCase ) {
+			$status = Status::newGood(); // nothing to do
+		} elseif ( $this->params['src'] === $this->params['dst'] ) {
+			// Just update the destination file headers
+			$headers = $this->getParam( 'headers' ) ?: array();
+			$status = $this->backend->describeInternal( $this->setFlags( array(
+				'src' => $this->params['dst'], 'headers' => $headers
+			) ) );
+		} else {
+			// Copy the file to the destination
+			$status = $this->backend->copyInternal( $this->setFlags( $this->params ) );
 		}
-		return Status::newGood();
+		return $status;
 	}
 
-	/**
-	 * @return array
-	 */
-	protected function doStoragePathsRead() {
+	public function storagePathsRead() {
 		return array( $this->params['src'] );
 	}
 
-	/**
-	 * @return array
-	 */
-	protected function doStoragePathsChanged() {
+	public function storagePathsChanged() {
 		return array( $this->params['dst'] );
 	}
 }
@@ -636,25 +638,26 @@ class CopyFileOp extends FileOp {
  * Parameters for this operation are outlined in FileBackend::doOperations().
  */
 class MoveFileOp extends FileOp {
-	/**
-	 * @return array
-	 */
 	protected function allowedParams() {
 		return array( array( 'src', 'dst' ),
-			array( 'overwrite', 'overwriteSame', 'disposition' ) );
+			array( 'overwrite', 'overwriteSame', 'ignoreMissingSource', 'headers' ) );
 	}
 
-	/**
-	 * @param $predicates array
-	 * @return Status
-	 */
 	protected function doPrecheck( array &$predicates ) {
 		$status = Status::newGood();
 		// Check if the source file exists
 		if ( !$this->fileExists( $this->params['src'], $predicates ) ) {
-			$status->fatal( 'backend-fail-notexists', $this->params['src'] );
-			return $status;
-		// Check if a file can be placed at the destination
+			if ( $this->getParam( 'ignoreMissingSource' ) ) {
+				$this->doOperation = false; // no-op
+				// Update file existence predicates (cache 404s)
+				$predicates['exists'][$this->params['src']] = false;
+				$predicates['sha1'][$this->params['src']] = false;
+				return $status; // nothing to do
+			} else {
+				$status->fatal( 'backend-fail-notexists', $this->params['src'] );
+				return $status;
+			}
+		// Check if a file can be placed/changed at the destination
 		} elseif ( !$this->backend->isPathUsableInternal( $this->params['dst'] ) ) {
 			$status->fatal( 'backend-fail-usable', $this->params['dst'] );
 			$status->fatal( 'backend-fail-move', $this->params['src'], $this->params['dst'] );
@@ -662,6 +665,7 @@ class MoveFileOp extends FileOp {
 		}
 		// Check if destination file exists
 		$status->merge( $this->precheckDestExistence( $predicates ) );
+		$this->params['dstExists'] = $this->destExists; // see FileBackendStore::setFileCache()
 		if ( $status->isOK() ) {
 			// Update file existence predicates
 			$predicates['exists'][$this->params['src']] = false;
@@ -672,35 +676,35 @@ class MoveFileOp extends FileOp {
 		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return Status
-	 */
 	protected function doAttempt() {
-		// Do nothing if the src/dst paths are the same
-		if ( $this->params['src'] !== $this->params['dst'] ) {
-			if ( !$this->destSameAsSource ) {
-				// Move the file into the destination
-				return $this->backend->moveInternal( $this->setFlags( $this->params ) );
+		if ( $this->overwriteSameCase ) {
+			if ( $this->params['src'] === $this->params['dst'] ) {
+				// Do nothing to the destination (which is also the source)
+				$status = Status::newGood();
 			} else {
-				// Just delete source as the destination needs no changes
-				$params = array( 'src' => $this->params['src'] );
-				return $this->backend->deleteInternal( $this->setFlags( $params ) );
+				// Just delete the source as the destination file needs no changes
+				$status = $this->backend->deleteInternal( $this->setFlags(
+					array( 'src' => $this->params['src'] )
+				) );
 			}
+		} elseif ( $this->params['src'] === $this->params['dst'] ) {
+			// Just update the destination file headers
+			$headers = $this->getParam( 'headers' ) ?: array();
+			$status = $this->backend->describeInternal( $this->setFlags(
+				array( 'src' => $this->params['dst'], 'headers' => $headers )
+			) );
+		} else {
+			// Move the file to the destination
+			$status = $this->backend->moveInternal( $this->setFlags( $this->params ) );
 		}
-		return Status::newGood();
+		return $status;
 	}
 
-	/**
-	 * @return array
-	 */
-	protected function doStoragePathsRead() {
+	public function storagePathsRead() {
 		return array( $this->params['src'] );
 	}
 
-	/**
-	 * @return array
-	 */
-	protected function doStoragePathsChanged() {
+	public function storagePathsChanged() {
 		return array( $this->params['src'], $this->params['dst'] );
 	}
 }
@@ -710,28 +714,29 @@ class MoveFileOp extends FileOp {
  * Parameters for this operation are outlined in FileBackend::doOperations().
  */
 class DeleteFileOp extends FileOp {
-	/**
-	 * @return array
-	 */
 	protected function allowedParams() {
 		return array( array( 'src' ), array( 'ignoreMissingSource' ) );
 	}
 
-	protected $needsDelete = true;
-
-	/**
-	 * @param array $predicates
-	 * @return Status
-	 */
 	protected function doPrecheck( array &$predicates ) {
 		$status = Status::newGood();
 		// Check if the source file exists
 		if ( !$this->fileExists( $this->params['src'], $predicates ) ) {
-			if ( !$this->getParam( 'ignoreMissingSource' ) ) {
+			if ( $this->getParam( 'ignoreMissingSource' ) ) {
+				$this->doOperation = false; // no-op
+				// Update file existence predicates (cache 404s)
+				$predicates['exists'][$this->params['src']] = false;
+				$predicates['sha1'][$this->params['src']] = false;
+				return $status; // nothing to do
+			} else {
 				$status->fatal( 'backend-fail-notexists', $this->params['src'] );
 				return $status;
 			}
-			$this->needsDelete = false;
+		// Check if a file can be placed/changed at the source
+		} elseif ( !$this->backend->isPathUsableInternal( $this->params['src'] ) ) {
+			$status->fatal( 'backend-fail-usable', $this->params['src'] );
+			$status->fatal( 'backend-fail-delete', $this->params['src'] );
+			return $status;
 		}
 		// Update file existence predicates
 		$predicates['exists'][$this->params['src']] = false;
@@ -739,21 +744,51 @@ class DeleteFileOp extends FileOp {
 		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return Status
-	 */
 	protected function doAttempt() {
-		if ( $this->needsDelete ) {
-			// Delete the source file
-			return $this->backend->deleteInternal( $this->setFlags( $this->params ) );
+		// Delete the source file
+		return $this->backend->deleteInternal( $this->setFlags( $this->params ) );
+	}
+
+	public function storagePathsChanged() {
+		return array( $this->params['src'] );
+	}
+}
+
+/**
+ * Change metadata for a file at the given storage path in the backend.
+ * Parameters for this operation are outlined in FileBackend::doOperations().
+ */
+class DescribeFileOp extends FileOp {
+	protected function allowedParams() {
+		return array( array( 'src' ), array( 'headers' ) );
+	}
+
+	protected function doPrecheck( array &$predicates ) {
+		$status = Status::newGood();
+		// Check if the source file exists
+		if ( !$this->fileExists( $this->params['src'], $predicates ) ) {
+			$status->fatal( 'backend-fail-notexists', $this->params['src'] );
+			return $status;
+		// Check if a file can be placed/changed at the source
+		} elseif ( !$this->backend->isPathUsableInternal( $this->params['src'] ) ) {
+			$status->fatal( 'backend-fail-usable', $this->params['src'] );
+			$status->fatal( 'backend-fail-describe', $this->params['src'] );
+			return $status;
 		}
-		return Status::newGood();
+		// Update file existence predicates
+		$predicates['exists'][$this->params['src']] =
+			$this->fileExists( $this->params['src'], $predicates );
+		$predicates['sha1'][$this->params['src']] =
+			$this->fileSha1( $this->params['src'], $predicates );
+		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return array
-	 */
-	protected function doStoragePathsChanged() {
+	protected function doAttempt() {
+		// Update the source file's metadata
+		return $this->backend->describeInternal( $this->setFlags( $this->params ) );
+	}
+
+	public function storagePathsChanged() {
 		return array( $this->params['src'] );
 	}
 }
diff --git a/includes/filebackend/FileOpBatch.php b/includes/filebackend/FileOpBatch.php
index 33558725..785c0bc9 100644
--- a/includes/filebackend/FileOpBatch.php
+++ b/includes/filebackend/FileOpBatch.php
@@ -42,9 +42,6 @@ class FileOpBatch {
 	 * $opts is an array of options, including:
 	 *   - force        : Errors that would normally cause a rollback do not.
 	 *                    The remaining operations are still attempted if any fail.
-	 *   - allowStale   : Don't require the latest available data.
-	 *                    This can increase performance for non-critical writes.
-	 *                    This has no effect unless the 'force' flag is set.
 	 *   - nonJournaled : Don't log this operation batch in the file journal.
 	 *   - concurrency  : Try to do this many operations in parallel when possible.
 	 *
@@ -52,9 +49,9 @@ class FileOpBatch {
 	 *   - a) unexpected operation errors occurred (network partitions, disk full...)
 	 *   - b) significant operation errors occurred and 'force' was not set
 	 *
-	 * @param $performOps Array List of FileOp operations
-	 * @param $opts Array Batch operation options
-	 * @param $journal FileJournal Journal to log operations to
+	 * @param array $performOps List of FileOp operations
+	 * @param array $opts Batch operation options
+	 * @param FileJournal $journal Journal to log operations to
 	 * @return Status
 	 */
 	public static function attempt( array $performOps, array $opts, FileJournal $journal ) {
@@ -69,7 +66,6 @@ class FileOpBatch {
 		}
 
 		$batchId = $journal->getTimestampedUUID();
-		$allowStale = !empty( $opts['allowStale'] );
 		$ignoreErrors = !empty( $opts['force'] );
 		$journaled = empty( $opts['nonJournaled'] );
 		$maxConcurrency = isset( $opts['concurrency'] ) ? $opts['concurrency'] : 1;
@@ -84,7 +80,6 @@ class FileOpBatch {
 		foreach ( $performOps as $index => $fileOp ) {
 			$backendName = $fileOp->getBackend()->getName();
 			$fileOp->setBatchId( $batchId ); // transaction ID
-			$fileOp->allowStaleReads( $allowStale ); // consistency level
 			// Decide if this op can be done concurrently within this sub-batch
 			// or if a new concurrent sub-batch must be started after this one...
 			if ( $fileOp->dependsOn( $curBatchDeps )
@@ -136,49 +131,13 @@ class FileOpBatch {
 		}
 
 		// Attempt each operation (in parallel if allowed and possible)...
-		if ( count( $pPerformOps ) < count( $performOps ) ) {
-			self::runBatchParallel( $pPerformOps, $status );
-		} else {
-			self::runBatchSeries( $performOps, $status );
-		}
+		self::runParallelBatches( $pPerformOps, $status );
 
 		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
 	/**
-	 * Attempt a list of file operations in series.
-	 * This will abort remaining ops on failure.
-	 *
-	 * @param $performOps Array
-	 * @param $status Status
-	 * @return bool Success
-	 */
-	protected static function runBatchSeries( array $performOps, Status $status ) {
-		foreach ( $performOps as $index => $fileOp ) {
-			if ( $fileOp->failed() ) {
-				continue; // nothing to do
-			}
-			$subStatus = $fileOp->attempt();
-			$status->merge( $subStatus );
-			if ( $subStatus->isOK() ) {
-				$status->success[$index] = true;
-				++$status->successCount;
-			} else {
-				$status->success[$index] = false;
-				++$status->failCount;
-				// We can't continue (even with $ignoreErrors) as $predicates is wrong.
-				// Log the remaining ops as failed for recovery...
-				for ( $i = ($index + 1); $i < count( $performOps ); $i++ ) {
-					$performOps[$i]->logFailure( 'attempt_aborted' );
-				}
-				return false; // bail out
-			}
-		}
-		return true;
-	}
-
-	/**
 	 * Attempt a list of file operations sub-batches in series.
 	 *
 	 * The operations *in* each sub-batch will be done in parallel.
@@ -186,12 +145,12 @@ class FileOpBatch {
 	 * within any given sub-batch do not depend on each other.
 	 * This will abort remaining ops on failure.
 	 *
-	 * @param $pPerformOps Array
-	 * @param $status Status
+	 * @param Array $pPerformOps
+	 * @param Status $status
 	 * @return bool Success
 	 */
-	protected static function runBatchParallel( array $pPerformOps, Status $status ) {
-		$aborted = false;
+	protected static function runParallelBatches( array $pPerformOps, Status $status ) {
+		$aborted = false; // set to true on unexpected errors
 		foreach ( $pPerformOps as $performOpsBatch ) {
 			if ( $aborted ) { // check batch op abort flag...
 				// We can't continue (even with $ignoreErrors) as $predicates is wrong.
@@ -205,11 +164,16 @@ class FileOpBatch {
 			$opHandles = array();
 			// Get the backend; all sub-batch ops belong to a single backend
 			$backend = reset( $performOpsBatch )->getBackend();
-			// If attemptAsync() returns synchronously, it was either an
-			// error Status or the backend just doesn't support async ops.
+			// Get the operation handles or actually do it if there is just one.
+			// If attemptAsync() returns a Status, it was either due to an error
+			// or the backend does not support async ops and did it synchronously.
 			foreach ( $performOpsBatch as $i => $fileOp ) {
 				if ( !$fileOp->failed() ) { // failed => already has Status
-					$subStatus = $fileOp->attemptAsync();
+					// If the batch is just one operation, it's faster to avoid
+					// pipelining as that can involve creating new TCP connections.
+					$subStatus = ( count( $performOpsBatch ) > 1 )
+						? $fileOp->attemptAsync()
+						: $fileOp->attempt();
 					if ( $subStatus->value instanceof FileBackendStoreOpHandle ) {
 						$opHandles[$i] = $subStatus->value; // deferred
 					} else {
diff --git a/includes/filebackend/README b/includes/filebackend/README
new file mode 100644
index 00000000..569f3376
--- /dev/null
+++ b/includes/filebackend/README
@@ -0,0 +1,208 @@
+/*!
+\ingroup FileBackend
+\page file_backend_design File backend design
+
+Some notes on the FileBackend architecture.
+
+\section intro Introduction
+
+To abstract away the differences among different types of storage media,
+MediaWiki is providing an interface known as FileBackend. Any MediaWiki
+interaction with stored files should thus use a FileBackend object.
+
+Different types of backing storage media are supported (ranging from local
+file system to distributed object stores). The types include:
+
+* FSFileBackend (used for mounted file systems)
+* SwiftFileBackend (used for Swift or Ceph Rados+RGW object stores)
+* FileBackendMultiWrite (useful for transitioning from one backend to another)
+
+Configuration documentation for each type of backend is to be found in their
+__construct() inline documentation.
+
+
+\section setup Setup
+
+File backends are registered in LocalSettings.php via the global variable
+$wgFileBackends. To access one of those defined backends, one would use
+FileBackendStore::get( <name> ) which will bring back a FileBackend object
+handle. Such handles are reused for any subsequent get() call (via singleton).
+The FileBackends objects are caching request calls such as file stats,
+SHA1 requests or TCP connection handles.
+
+\par Note:
+Some backends may require additional PHP extensions to be enabled or can rely on a
+MediaWiki extension. This is often the case when a FileBackend subclass makes use of an
+upstream client API for communicating with the backing store.
+
+
+\section fileoperations File operations
+
+The MediaWiki FileBackend API supports various operations on either files or
+directories. See FileBackend.php for full documentation for each function.
+
+
+\subsection reading Reading
+
+The following basic operations are supported for reading from a backend:
+
+On files:
+* stat a file for basic information (timestamp, size)
+* read a file into a string or  several files into a map of path names to strings
+* download a file or set of files to a temporary file (on a mounted file system)
+* get the SHA1 hash of a file
+* get various properties of a file (stat information, content time, mime information, ...)
+
+On directories:
+* get a list of files directly under a directory
+* get a recursive list of files under a directory
+* get a list of directories directly under a directory
+* get a recursive list of directories under a directory
+
+\par Note:
+Backend handles should return directory listings as iterators, all though in some cases
+they may just be simple arrays (which can still be iterated over). Iterators allow for
+callers to traverse a large number of file listings without consuming excessive RAM in
+the process. Either the memory consumed is flatly bounded (if the iterator does paging)
+or it is proportional to the depth of the portion of the directory tree being traversed
+(if the iterator works via recursion).
+
+
+\subsection writing Writing
+
+The following basic operations are supported for writing or changing in the backend:
+
+On files:
+* store (copying a mounted file system file into storage)
+* create (creating a file within storage from a string)
+* copy (within storage)
+* move (within storage)
+* delete (within storage)
+* lock/unlock (lock or unlock a file in storage)
+
+The following operations are supported for writing directories in the backend:
+* prepare (create parent container and directories for a path)
+* secure (try to lock-down access to a container)
+* publish (try to reverse the effects of secure)
+* clean (remove empty containers or directories)
+
+
+\subsection invokingoperation Invoking an operation
+
+Generally, callers should use doOperations() or doQuickOperations() when doing
+batches of changes, rather than making a suite of single operation calls. This
+makes the system tolerate high latency much better by pipelining operations
+when possible.
+
+doOperations() should be used for working on important original data, i.e. when
+consistency is important. The former will only pipeline operations that do not
+depend on each other. It is best if the operations that do not depend on each
+other occur in consecutive groups. This function can also log file changes to
+a journal (see FileJournal), which can be used to sync two backend instances.
+One might use this function for user uploads of file for example.
+
+doQuickOperations() is more geared toward ephemeral items that can be easily
+regenerated from original data. It will always pipeline without checking for
+dependencies within the operation batch. One might use this function for
+creating and purging generated thumbnails of original files for example.
+
+
+\section consistency Consistency
+
+Not all backing stores are sequentially consistent by default. Various FileBackend
+functions offer a "latest" option that can be passed in to assure (or try to assure)
+that the latest version of the file is read. Some backing stores are consistent by
+default, but callers should always assume that without this option, stale data may
+be read. This is actually true for stores that have eventual consistency.
+
+Note that file listing functions have no "latest" flag, and thus some systems may
+return stale data. Thus callers should avoid assuming that listings contain changes
+made my the current client or any other client from a very short time ago. For example,
+creating a file under a directory and then immediately doing a file listing operation
+on that directory may result in a listing that does not include that file.
+
+
+\section locking Locking
+
+Locking is effective if and only if a proper lock manager is registered and is
+actually being used by the backend. Lock managers can be registered in LocalSettings.php
+using the $wgLockManagers global configuration variable.
+
+For object stores, locking is not generally useful for avoiding partially
+written or read objects, since most stores use Multi Version Concurrency
+Control (MVCC) to avoid this. However, locking can be important when:
+* One or more operations must be done without objects changing in the meantime.
+* It can also be useful when a file read is used to determine a file write or DB change.
+  For example, doOperations() first checks that there will be no "file already exists"
+  or "file does not exist" type errors before attempting an operation batch. This works
+  by stating the files first, and is only safe if the files are locked in the meantime.
+
+When locking, callers should use the latest available file data for reads.
+Also, one should always lock the file *before* reading it, not after. If stale data is
+used to determine a write, there will be some data corruption, even when reads of the
+original file finally start returning the updated data without needing the "latest"
+option (eventual consistency). The "scoped" lock functions are preferable since
+there is not the problem of forgetting to unlock due to early returns or exceptions.
+
+Since acquiring locks can fail, and lock managers can be non-blocking, callers should:
+* Acquire all required locks up font
+* Be prepared for the case where locks fail to be acquired
+* Possible retry acquiring certain locks
+
+MVCC is also a useful pattern to use on top of the backend interface, because operations
+are not atomic, even with doOperations(), so doing complex batch file changes or changing
+files and updating a database row can result in partially written "transactions". Thus one
+should avoid changing files once they have been stored, except perhaps with ephemeral data
+that are tolerant of some degree of inconsistency.
+
+Callers can use their own locking (e.g. SELECT FOR UPDATE) if it is more convenient, but
+note that all callers that change any of the files should then go through functions that
+acquire these locks. For example, if a caller just directly uses the file backend store()
+function, it will ignore any custom "FOR UPDATE" locks, which can cause problems.
+
+\section objectstore Object stores
+
+Support for object stores (like Amazon S3/Swift) drive much of the API and design
+decisions of FileBackend, but using any POSIX compliant file systems works fine.
+The system essentially stores "files" in "containers". For a mounted file system
+as a backing store, "files" will just be files under directories. For an object store
+as a backing store, the "files" will be objects stored in actual containers.
+
+
+\section file_obj_diffs File system and Object store differences
+
+An advantage of object stores is the reduced Round-Trip Times. This is
+achieved by avoiding the need to create each parent directory before placing a
+file somewhere. It gets worse the deeper the directory hierarchy is. Another
+advantage of object stores is that object listings tend to use databases, which
+scale better than the linked list directories that file sytems sometimes use.
+File systems like btrfs and xfs use tree structures, which scale better.
+For both object stores and file systems, using "/" in filenames will allow for the
+intuitive use of directory functions. For example, creating a file in Swift
+called "container/a/b/file1" will mean that:
+- a "directory listing" of "container/a" will contain "b",
+- and a "file listing" of "b" will contain "file1"
+
+This means that switching from an object store to a file system and vise versa
+using the FileBackend interface will generally be harmless. However, one must be
+aware of some important differences:
+
+* In a file system, you cannot have a file and a directory within the same path
+  whereas it is possible in an object stores. Calling code should avoid any layouts
+  which allow files and directories at the same path.
+* Some file systems have file name length restrictions or overall path length
+  restrictions that others do not. The same goes with object stores which might
+  have a maximum object length or a limitation regarding the number of files
+  under a container or volume.
+* Latency varies among systems, certain access patterns may not be tolerable for
+  certain backends but may hold up for others. Some backend subclasses use
+  MediaWiki's object caching for serving stat requests, which can greatly
+  reduce latency. Making sure that the backend has pipelining (see the
+  "parallelize" and "concurrency" settings) enabled can also mask latency in
+  batch operation scenarios.
+* File systems may implement directories as linked-lists or other structures
+  with poor scalability, so calling code should use layouts that shard the data.
+  Instead of storing files like "container/file.txt", one can store files like
+  "container/<x>/<y>/file.txt". It is best if "sharding" optional or configurable.
+
+*/
diff --git a/includes/filebackend/SwiftFileBackend.php b/includes/filebackend/SwiftFileBackend.php
index b6f0aa60..db090a98 100644
--- a/includes/filebackend/SwiftFileBackend.php
+++ b/includes/filebackend/SwiftFileBackend.php
@@ -24,7 +24,7 @@
  */
 
 /**
- * @brief Class for an OpenStack Swift based file backend.
+ * @brief Class for an OpenStack Swift (or Ceph RGW) based file backend.
  *
  * This requires the SwiftCloudFiles MediaWiki extension, which includes
  * the php-cloudfiles library (https://github.com/rackspace/php-cloudfiles).
@@ -40,11 +40,16 @@ class SwiftFileBackend extends FileBackendStore {
 	/** @var CF_Authentication */
 	protected $auth; // Swift authentication handler
 	protected $authTTL; // integer seconds
+	protected $swiftTempUrlKey; // string; shared secret value for making temp urls
 	protected $swiftAnonUser; // string; username to handle unauthenticated requests
 	protected $swiftUseCDN; // boolean; whether CloudFiles CDN is enabled
 	protected $swiftCDNExpiry; // integer; how long to cache things in the CDN
 	protected $swiftCDNPurgable; // boolean; whether object CDN purging is enabled
 
+	// Rados Gateway specific options
+	protected $rgwS3AccessKey; // string; S3 access key
+	protected $rgwS3SecretKey; // string; S3 authentication key
+
 	/** @var CF_Connection */
 	protected $conn; // Swift connection handle
 	protected $sessionStarted = 0; // integer UNIX timestamp
@@ -66,6 +71,8 @@ class SwiftFileBackend extends FileBackendStore {
 	 *   - swiftUser          : Swift user used by MediaWiki (account:username)
 	 *   - swiftKey           : Swift authentication key for the above user
 	 *   - swiftAuthTTL       : Swift authentication TTL (seconds)
+	 *   - swiftTempUrlKey    : Swift "X-Account-Meta-Temp-URL-Key" value on the account.
+	 *                          Do not set this until it has been set in the backend.
 	 *   - swiftAnonUser      : Swift user used for end-user requests (account:username).
 	 *                          If set, then views of public containers are assumed to go
 	 *                          through this user. If not set, then public containers are
@@ -84,10 +91,20 @@ class SwiftFileBackend extends FileBackendStore {
 	 *   - cacheAuthInfo      : Whether to cache authentication tokens in APC, XCache, ect.
 	 *                          If those are not available, then the main cache will be used.
 	 *                          This is probably insecure in shared hosting environments.
+	 *   - rgwS3AccessKey     : Ragos Gateway S3 "access key" value on the account.
+	 *                          Do not set this until it has been set in the backend.
+	 *                          This is used for generating expiring pre-authenticated URLs.
+	 *                          Only use this when using rgw and to work around
+	 *                          http://tracker.newdream.net/issues/3454.
+	 *   - rgwS3SecretKey     : Ragos Gateway S3 "secret key" value on the account.
+	 *                          Do not set this until it has been set in the backend.
+	 *                          This is used for generating expiring pre-authenticated URLs.
+	 *                          Only use this when using rgw and to work around
+	 *                          http://tracker.newdream.net/issues/3454.
 	 */
 	public function __construct( array $config ) {
 		parent::__construct( $config );
-		if ( !MWInit::classExists( 'CF_Constants' ) ) {
+		if ( !class_exists( 'CF_Constants' ) ) {
 			throw new MWException( 'SwiftCloudFiles extension not installed.' );
 		}
 		// Required settings
@@ -104,6 +121,9 @@ class SwiftFileBackend extends FileBackendStore {
 		$this->swiftAnonUser = isset( $config['swiftAnonUser'] )
 			? $config['swiftAnonUser']
 			: '';
+		$this->swiftTempUrlKey = isset( $config['swiftTempUrlKey'] )
+			? $config['swiftTempUrlKey']
+			: '';
 		$this->shardViaHashLevels = isset( $config['shardViaHashLevels'] )
 			? $config['shardViaHashLevels']
 			: '';
@@ -112,17 +132,23 @@ class SwiftFileBackend extends FileBackendStore {
 			: false;
 		$this->swiftCDNExpiry = isset( $config['swiftCDNExpiry'] )
 			? $config['swiftCDNExpiry']
-			: 12*3600; // 12 hours is safe (tokens last 24 hours per http://docs.openstack.org)
+			: 12 * 3600; // 12 hours is safe (tokens last 24 hours per http://docs.openstack.org)
 		$this->swiftCDNPurgable = isset( $config['swiftCDNPurgable'] )
 			? $config['swiftCDNPurgable']
 			: true;
+		$this->rgwS3AccessKey = isset( $config['rgwS3AccessKey'] )
+			? $config['rgwS3AccessKey']
+			: '';
+		$this->rgwS3SecretKey = isset( $config['rgwS3SecretKey'] )
+			? $config['rgwS3SecretKey']
+			: '';
 		// Cache container information to mask latency
 		$this->memCache = wfGetMainCache();
 		// Process cache for container info
 		$this->connContainerCache = new ProcessCacheLRU( 300 );
 		// Cache auth token information to avoid RTTs
 		if ( !empty( $config['cacheAuthInfo'] ) ) {
-			if ( php_sapi_name() === 'cli' ) {
+			if ( PHP_SAPI === 'cli' ) {
 				$this->srvCache = wfGetMainCache(); // preferrably memcached
 			} else {
 				try { // look for APC, XCache, WinCache, ect...
@@ -146,10 +172,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $relStoragePath;
 	}
 
-	/**
-	 * @see FileBackendStore::isPathUsableInternal()
-	 * @return bool
-	 */
 	public function isPathUsableInternal( $storagePath ) {
 		list( $container, $rel ) = $this->resolveStoragePathReal( $storagePath );
 		if ( $rel === null ) {
@@ -168,14 +190,26 @@ class SwiftFileBackend extends FileBackendStore {
 	}
 
 	/**
-	 * @param $disposition string Content-Disposition header value
+	 * @param array $headers
+	 * @return array
+	 */
+	protected function sanitizeHdrs( array $headers ) {
+		// By default, Swift has annoyingly low maximum header value limits
+		if ( isset( $headers['Content-Disposition'] ) ) {
+			$headers['Content-Disposition'] = $this->truncDisp( $headers['Content-Disposition'] );
+		}
+		return $headers;
+	}
+
+	/**
+	 * @param string $disposition Content-Disposition header value
 	 * @return string Truncated Content-Disposition header value to meet Swift limits
 	 */
 	protected function truncDisp( $disposition ) {
 		$res = '';
 		foreach ( explode( ';', $disposition ) as $part ) {
 			$part = trim( $part );
-			$new  = ( $res === '' ) ? $part : "{$res};{$part}";
+			$new = ( $res === '' ) ? $part : "{$res};{$part}";
 			if ( strlen( $new ) <= 255 ) {
 				$res = $new;
 			} else {
@@ -185,10 +219,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $res;
 	}
 
-	/**
-	 * @see FileBackendStore::doCreateInternal()
-	 * @return Status
-	 */
 	protected function doCreateInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -201,12 +231,6 @@ class SwiftFileBackend extends FileBackendStore {
 		// (a) Check the destination container and object
 		try {
 			$dContObj = $this->getContainer( $dstCont );
-			if ( empty( $params['overwrite'] ) &&
-				$this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) )
-			{
-				$status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
-				return $status;
-			}
 		} catch ( NoSuchContainerException $e ) {
 			$status->fatal( 'backend-fail-create', $params['dst'] );
 			return $status;
@@ -223,31 +247,23 @@ class SwiftFileBackend extends FileBackendStore {
 			// Create a fresh CF_Object with no fields preloaded.
 			// We don't want to preserve headers, metadata, and such.
 			$obj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
-			// Note: metadata keys stored as [Upper case char][[Lower case char]...]
-			$obj->metadata = array( 'Sha1base36' => $sha1Hash );
+			$obj->setMetadataValues( array( 'Sha1base36' => $sha1Hash ) );
 			// Manually set the ETag (https://github.com/rackspace/php-cloudfiles/issues/59).
 			// The MD5 here will be checked within Swift against its own MD5.
 			$obj->set_etag( md5( $params['content'] ) );
 			// Use the same content type as StreamFile for security
-			$obj->content_type = StreamFile::contentTypeFromPath( $params['dst'] );
-			if ( !strlen( $obj->content_type ) ) { // special case
-				$obj->content_type = 'unknown/unknown';
-			}
-			// Set the Content-Disposition header if requested
-			if ( isset( $params['disposition'] ) ) {
-				$obj->headers['Content-Disposition'] = $this->truncDisp( $params['disposition'] );
+			$obj->content_type = $this->getContentType( $params['dst'], $params['content'], null );
+			// Set any other custom headers if requested
+			if ( isset( $params['headers'] ) ) {
+				$obj->headers += $this->sanitizeHdrs( $params['headers'] );
 			}
 			if ( !empty( $params['async'] ) ) { // deferred
 				$op = $obj->write_async( $params['content'] );
 				$status->value = new SwiftFileOpHandle( $this, $params, 'Create', $op );
-				if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
-					$status->value->affectedObjects[] = $obj;
-				}
+				$status->value->affectedObjects[] = $obj;
 			} else { // actually write the object in Swift
 				$obj->write( $params['content'] );
-				if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
-					$this->purgeCDNCache( array( $obj ) );
-				}
+				$this->purgeCDNCache( array( $obj ) );
 			}
 		} catch ( CDNNotEnabledException $e ) {
 			// CDN not enabled; nothing to see here
@@ -271,10 +287,6 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doStoreInternal()
-	 * @return Status
-	 */
 	protected function doStoreInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -287,12 +299,6 @@ class SwiftFileBackend extends FileBackendStore {
 		// (a) Check the destination container and object
 		try {
 			$dContObj = $this->getContainer( $dstCont );
-			if ( empty( $params['overwrite'] ) &&
-				$this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) )
-			{
-				$status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
-				return $status;
-			}
 		} catch ( NoSuchContainerException $e ) {
 			$status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
 			return $status;
@@ -302,7 +308,9 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 
 		// (b) Get a SHA-1 hash of the object
+		wfSuppressWarnings();
 		$sha1Hash = sha1_file( $params['src'] );
+		wfRestoreWarnings();
 		if ( $sha1Hash === false ) { // source doesn't exist?
 			$status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
 			return $status;
@@ -314,18 +322,14 @@ class SwiftFileBackend extends FileBackendStore {
 			// Create a fresh CF_Object with no fields preloaded.
 			// We don't want to preserve headers, metadata, and such.
 			$obj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
-			// Note: metadata keys stored as [Upper case char][[Lower case char]...]
-			$obj->metadata = array( 'Sha1base36' => $sha1Hash );
+			$obj->setMetadataValues( array( 'Sha1base36' => $sha1Hash ) );
 			// The MD5 here will be checked within Swift against its own MD5.
 			$obj->set_etag( md5_file( $params['src'] ) );
 			// Use the same content type as StreamFile for security
-			$obj->content_type = StreamFile::contentTypeFromPath( $params['dst'] );
-			if ( !strlen( $obj->content_type ) ) { // special case
-				$obj->content_type = 'unknown/unknown';
-			}
-			// Set the Content-Disposition header if requested
-			if ( isset( $params['disposition'] ) ) {
-				$obj->headers['Content-Disposition'] = $this->truncDisp( $params['disposition'] );
+			$obj->content_type = $this->getContentType( $params['dst'], null, $params['src'] );
+			// Set any other custom headers if requested
+			if ( isset( $params['headers'] ) ) {
+				$obj->headers += $this->sanitizeHdrs( $params['headers'] );
 			}
 			if ( !empty( $params['async'] ) ) { // deferred
 				wfSuppressWarnings();
@@ -337,15 +341,11 @@ class SwiftFileBackend extends FileBackendStore {
 					$op = $obj->write_async( $fp, filesize( $params['src'] ), true );
 					$status->value = new SwiftFileOpHandle( $this, $params, 'Store', $op );
 					$status->value->resourcesToClose[] = $fp;
-					if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
-						$status->value->affectedObjects[] = $obj;
-					}
+					$status->value->affectedObjects[] = $obj;
 				}
 			} else { // actually write the object in Swift
 				$obj->load_from_filename( $params['src'], true ); // calls $obj->write()
-				if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
-					$this->purgeCDNCache( array( $obj ) );
-				}
+				$this->purgeCDNCache( array( $obj ) );
 			}
 		} catch ( CDNNotEnabledException $e ) {
 			// CDN not enabled; nothing to see here
@@ -373,10 +373,6 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doCopyInternal()
-	 * @return Status
-	 */
 	protected function doCopyInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -396,14 +392,10 @@ class SwiftFileBackend extends FileBackendStore {
 		try {
 			$sContObj = $this->getContainer( $srcCont );
 			$dContObj = $this->getContainer( $dstCont );
-			if ( empty( $params['overwrite'] ) &&
-				$this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) )
-			{
-				$status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
-				return $status;
-			}
 		} catch ( NoSuchContainerException $e ) {
-			$status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
+			if ( empty( $params['ignoreMissingSource'] ) || isset( $sContObj ) ) {
+				$status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
+			}
 			return $status;
 		} catch ( CloudFilesException $e ) { // some other exception?
 			$this->handleException( $e, $status, __METHOD__, $params );
@@ -414,25 +406,24 @@ class SwiftFileBackend extends FileBackendStore {
 		try {
 			$dstObj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
 			$hdrs = array(); // source file headers to override with new values
-			if ( isset( $params['disposition'] ) ) {
-				$hdrs['Content-Disposition'] = $this->truncDisp( $params['disposition'] );
+			// Set any other custom headers if requested
+			if ( isset( $params['headers'] ) ) {
+				$hdrs += $this->sanitizeHdrs( $params['headers'] );
 			}
 			if ( !empty( $params['async'] ) ) { // deferred
 				$op = $sContObj->copy_object_to_async( $srcRel, $dContObj, $dstRel, null, $hdrs );
 				$status->value = new SwiftFileOpHandle( $this, $params, 'Copy', $op );
-				if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
-					$status->value->affectedObjects[] = $dstObj;
-				}
+				$status->value->affectedObjects[] = $dstObj;
 			} else { // actually write the object in Swift
 				$sContObj->copy_object_to( $srcRel, $dContObj, $dstRel, null, $hdrs );
-				if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
-					$this->purgeCDNCache( array( $dstObj ) );
-				}
+				$this->purgeCDNCache( array( $dstObj ) );
 			}
 		} catch ( CDNNotEnabledException $e ) {
 			// CDN not enabled; nothing to see here
 		} catch ( NoSuchObjectException $e ) { // source object does not exist
-			$status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
+			if ( empty( $params['ignoreMissingSource'] ) ) {
+				$status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
+			}
 		} catch ( CloudFilesException $e ) { // some other exception?
 			$this->handleException( $e, $status, __METHOD__, $params );
 		}
@@ -451,10 +442,6 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doMoveInternal()
-	 * @return Status
-	 */
 	protected function doMoveInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -474,14 +461,10 @@ class SwiftFileBackend extends FileBackendStore {
 		try {
 			$sContObj = $this->getContainer( $srcCont );
 			$dContObj = $this->getContainer( $dstCont );
-			if ( empty( $params['overwrite'] ) &&
-				$this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) )
-			{
-				$status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
-				return $status;
-			}
 		} catch ( NoSuchContainerException $e ) {
-			$status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
+			if ( empty( $params['ignoreMissingSource'] ) || isset( $sContObj ) ) {
+				$status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
+			}
 			return $status;
 		} catch ( CloudFilesException $e ) { // some other exception?
 			$this->handleException( $e, $status, __METHOD__, $params );
@@ -493,27 +476,26 @@ class SwiftFileBackend extends FileBackendStore {
 			$srcObj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
 			$dstObj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
 			$hdrs = array(); // source file headers to override with new values
-			if ( isset( $params['disposition'] ) ) {
-				$hdrs['Content-Disposition'] = $this->truncDisp( $params['disposition'] );
+			// Set any other custom headers if requested
+			if ( isset( $params['headers'] ) ) {
+				$hdrs += $this->sanitizeHdrs( $params['headers'] );
 			}
 			if ( !empty( $params['async'] ) ) { // deferred
 				$op = $sContObj->move_object_to_async( $srcRel, $dContObj, $dstRel, null, $hdrs );
 				$status->value = new SwiftFileOpHandle( $this, $params, 'Move', $op );
 				$status->value->affectedObjects[] = $srcObj;
-				if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
-					$status->value->affectedObjects[] = $dstObj;
-				}
+				$status->value->affectedObjects[] = $dstObj;
 			} else { // actually write the object in Swift
 				$sContObj->move_object_to( $srcRel, $dContObj, $dstRel, null, $hdrs );
 				$this->purgeCDNCache( array( $srcObj ) );
-				if ( !empty( $params['overwrite'] ) ) { // file possibly mutated
-					$this->purgeCDNCache( array( $dstObj ) );
-				}
+				$this->purgeCDNCache( array( $dstObj ) );
 			}
 		} catch ( CDNNotEnabledException $e ) {
 			// CDN not enabled; nothing to see here
 		} catch ( NoSuchObjectException $e ) { // source object does not exist
-			$status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
+			if ( empty( $params['ignoreMissingSource'] ) ) {
+				$status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
+			}
 		} catch ( CloudFilesException $e ) { // some other exception?
 			$this->handleException( $e, $status, __METHOD__, $params );
 		}
@@ -532,10 +514,6 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doDeleteInternal()
-	 * @return Status
-	 */
 	protected function doDeleteInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -559,7 +537,9 @@ class SwiftFileBackend extends FileBackendStore {
 		} catch ( CDNNotEnabledException $e ) {
 			// CDN not enabled; nothing to see here
 		} catch ( NoSuchContainerException $e ) {
-			$status->fatal( 'backend-fail-delete', $params['src'] );
+			if ( empty( $params['ignoreMissingSource'] ) ) {
+				$status->fatal( 'backend-fail-delete', $params['src'] );
+			}
 		} catch ( NoSuchObjectException $e ) {
 			if ( empty( $params['ignoreMissingSource'] ) ) {
 				$status->fatal( 'backend-fail-delete', $params['src'] );
@@ -586,16 +566,45 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doPrepareInternal()
-	 * @return Status
-	 */
+	protected function doDescribeInternal( array $params ) {
+		$status = Status::newGood();
+
+		list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
+		if ( $srcRel === null ) {
+			$status->fatal( 'backend-fail-invalidpath', $params['src'] );
+			return $status;
+		}
+
+		try {
+			$sContObj = $this->getContainer( $srcCont );
+			// Get the latest version of the current metadata
+			$srcObj = $sContObj->get_object( $srcRel,
+				$this->headersFromParams( array( 'latest' => true ) ) );
+			// Merge in the metadata updates...
+			if ( isset( $params['headers'] ) ) {
+				$srcObj->headers = $this->sanitizeHdrs( $params['headers'] ) + $srcObj->headers;
+			}
+			$srcObj->sync_metadata(); // save to Swift
+			$this->purgeCDNCache( array( $srcObj ) );
+		} catch ( CDNNotEnabledException $e ) {
+			// CDN not enabled; nothing to see here
+		} catch ( NoSuchContainerException $e ) {
+			$status->fatal( 'backend-fail-describe', $params['src'] );
+		} catch ( NoSuchObjectException $e ) {
+			$status->fatal( 'backend-fail-describe', $params['src'] );
+		} catch ( CloudFilesException $e ) { // some other exception?
+			$this->handleException( $e, $status, __METHOD__, $params );
+		}
+
+		return $status;
+	}
+
 	protected function doPrepareInternal( $fullCont, $dir, array $params ) {
 		$status = Status::newGood();
 
 		// (a) Check if container already exists
 		try {
-			$contObj = $this->getContainer( $fullCont );
+			$this->getContainer( $fullCont );
 			// NoSuchContainerException not thrown: container must exist
 			return $status; // already exists
 		} catch ( NoSuchContainerException $e ) {
@@ -703,10 +712,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doCleanInternal()
-	 * @return Status
-	 */
 	protected function doCleanInternal( $fullCont, $dir, array $params ) {
 		$status = Status::newGood();
 
@@ -742,10 +747,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doFileExists()
-	 * @return array|bool|null
-	 */
 	protected function doGetFileStat( array $params ) {
 		list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
 		if ( $srcRel === null ) {
@@ -760,8 +761,8 @@ class SwiftFileBackend extends FileBackendStore {
 			$stat = array(
 				// Convert dates like "Tue, 03 Jan 2012 22:01:04 GMT" to TS_MW
 				'mtime' => wfTimestamp( TS_MW, $srcObj->last_modified ),
-				'size'  => (int)$srcObj->content_length,
-				'sha1'  => $srcObj->metadata['Sha1base36']
+				'size' => (int)$srcObj->content_length,
+				'sha1' => $srcObj->getMetadataValue( 'Sha1base36' )
 			);
 		} catch ( NoSuchContainerException $e ) {
 		} catch ( NoSuchObjectException $e ) {
@@ -776,61 +777,103 @@ class SwiftFileBackend extends FileBackendStore {
 	/**
 	 * Fill in any missing object metadata and save it to Swift
 	 *
-	 * @param $obj CF_Object
-	 * @param $path string Storage path to object
+	 * @param CF_Object $obj
+	 * @param string $path Storage path to object
 	 * @return bool Success
 	 * @throws Exception cloudfiles exceptions
 	 */
 	protected function addMissingMetadata( CF_Object $obj, $path ) {
-		if ( isset( $obj->metadata['Sha1base36'] ) ) {
+		if ( $obj->getMetadataValue( 'Sha1base36' ) !== null ) {
 			return true; // nothing to do
 		}
 		wfProfileIn( __METHOD__ );
+		trigger_error( "$path was not stored with SHA-1 metadata.", E_USER_WARNING );
 		$status = Status::newGood();
 		$scopeLockS = $this->getScopedFileLocks( array( $path ), LockManager::LOCK_UW, $status );
 		if ( $status->isOK() ) {
-			# Do not stat the file in getLocalCopy() to avoid infinite loops
-			$tmpFile = $this->getLocalCopy( array( 'src' => $path, 'latest' => 1, 'nostat' => 1 ) );
+			$tmpFile = $this->getLocalCopy( array( 'src' => $path, 'latest' => 1 ) );
 			if ( $tmpFile ) {
 				$hash = $tmpFile->getSha1Base36();
 				if ( $hash !== false ) {
-					$obj->metadata['Sha1base36'] = $hash;
+					$obj->setMetadataValues( array( 'Sha1base36' => $hash ) );
 					$obj->sync_metadata(); // save to Swift
 					wfProfileOut( __METHOD__ );
 					return true; // success
 				}
 			}
 		}
-		$obj->metadata['Sha1base36'] = false;
+		trigger_error( "Unable to set SHA-1 metadata for $path", E_USER_WARNING );
+		$obj->setMetadataValues( array( 'Sha1base36' => false ) );
 		wfProfileOut( __METHOD__ );
 		return false; // failed
 	}
 
-	/**
-	 * @see FileBackend::getFileContents()
-	 * @return bool|null|string
-	 */
-	public function getFileContents( array $params ) {
-		list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
-		if ( $srcRel === null ) {
-			return false; // invalid storage path
-		}
+	protected function doGetFileContentsMulti( array $params ) {
+		$contents = array();
 
-		if ( !$this->fileExists( $params ) ) {
-			return null;
-		}
+		$ep = array_diff_key( $params, array( 'srcs' => 1 ) ); // for error logging
+		// Blindly create tmp files and stream to them, catching any exception if the file does
+		// not exist. Doing stats here is useless and will loop infinitely in addMissingMetadata().
+		foreach ( array_chunk( $params['srcs'], $params['concurrency'] ) as $pathBatch ) {
+			$cfOps = array(); // (path => CF_Async_Op)
 
-		$data = false;
-		try {
-			$sContObj = $this->getContainer( $srcCont );
-			$obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
-			$data = $obj->read( $this->headersFromParams( $params ) );
-		} catch ( NoSuchContainerException $e ) {
-		} catch ( CloudFilesException $e ) { // some other exception?
-			$this->handleException( $e, null, __METHOD__, $params );
+			foreach ( $pathBatch as $path ) { // each path in this concurrent batch
+				list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
+				if ( $srcRel === null ) {
+					$contents[$path] = false;
+					continue;
+				}
+				$data = false;
+				try {
+					$sContObj = $this->getContainer( $srcCont );
+					$obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
+					// Create a new temporary memory file...
+					$handle = fopen( 'php://temp', 'wb' );
+					if ( $handle ) {
+						$headers = $this->headersFromParams( $params );
+						if ( count( $pathBatch ) > 1 ) {
+							$cfOps[$path] = $obj->stream_async( $handle, $headers );
+							$cfOps[$path]->_file_handle = $handle; // close this later
+						} else {
+							$obj->stream( $handle, $headers );
+							rewind( $handle ); // start from the beginning
+							$data = stream_get_contents( $handle );
+							fclose( $handle );
+						}
+					} else {
+						$data = false;
+					}
+				} catch ( NoSuchContainerException $e ) {
+					$data = false;
+				} catch ( NoSuchObjectException $e ) {
+					$data = false;
+				} catch ( CloudFilesException $e ) { // some other exception?
+					$data = false;
+					$this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
+				}
+				$contents[$path] = $data;
+			}
+
+			$batch = new CF_Async_Op_Batch( $cfOps );
+			$cfOps = $batch->execute();
+			foreach ( $cfOps as $path => $cfOp ) {
+				try {
+					$cfOp->getLastResponse();
+					rewind( $cfOp->_file_handle ); // start from the beginning
+					$contents[$path] = stream_get_contents( $cfOp->_file_handle );
+				} catch ( NoSuchContainerException $e ) {
+					$contents[$path] = false;
+				} catch ( NoSuchObjectException $e ) {
+					$contents[$path] = false;
+				} catch ( CloudFilesException $e ) { // some other exception?
+					$contents[$path] = false;
+					$this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
+				}
+				fclose( $cfOp->_file_handle ); // close open handle
+			}
 		}
 
-		return $data;
+		return $contents;
 	}
 
 	/**
@@ -871,27 +914,28 @@ class SwiftFileBackend extends FileBackendStore {
 	/**
 	 * Do not call this function outside of SwiftFileBackendFileList
 	 *
-	 * @param $fullCont string Resolved container name
-	 * @param $dir string Resolved storage directory with no trailing slash
-	 * @param $after string|null Storage path of file to list items after
-	 * @param $limit integer Max number of items to list
-	 * @param $params Array Includes flag for 'topOnly'
-	 * @return Array List of relative paths of dirs directly under $dir
+	 * @param string $fullCont Resolved container name
+	 * @param string $dir Resolved storage directory with no trailing slash
+	 * @param string|null $after Storage path of file to list items after
+	 * @param integer $limit Max number of items to list
+	 * @param array $params Parameters for getDirectoryList()
+	 * @return Array List of resolved paths of directories directly under $dir
+	 * @throws FileBackendError
 	 */
 	public function getDirListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
 		$dirs = array();
 		if ( $after === INF ) {
 			return $dirs; // nothing more
 		}
-		wfProfileIn( __METHOD__ . '-' . $this->name );
 
+		$section = new ProfileSection( __METHOD__ . '-' . $this->name );
 		try {
 			$container = $this->getContainer( $fullCont );
 			$prefix = ( $dir == '' ) ? null : "{$dir}/";
 			// Non-recursive: only list dirs right under $dir
 			if ( !empty( $params['topOnly'] ) ) {
 				$objects = $container->list_objects( $limit, $after, $prefix, null, '/' );
-				foreach ( $objects as $object ) { // files and dirs
+				foreach ( $objects as $object ) { // files and directories
 					if ( substr( $object, -1 ) === '/' ) {
 						$dirs[] = $object; // directories end in '/'
 					}
@@ -903,7 +947,7 @@ class SwiftFileBackend extends FileBackendStore {
 				$objects = $container->list_objects( $limit, $after, $prefix );
 				foreach ( $objects as $object ) { // files
 					$objectDir = $this->getParentDir( $object ); // directory of object
-					if ( $objectDir !== false ) { // file has a parent dir
+					if ( $objectDir !== false && $objectDir !== $dir ) {
 						// Swift stores paths in UTF-8, using binary sorting.
 						// See function "create_container_table" in common/db.py.
 						// If a directory is not "greater" than the last one,
@@ -922,6 +966,7 @@ class SwiftFileBackend extends FileBackendStore {
 					}
 				}
 			}
+			// Page on the unfiltered directory listing (what is returned may be filtered)
 			if ( count( $objects ) < $limit ) {
 				$after = INF; // avoid a second RTT
 			} else {
@@ -931,9 +976,9 @@ class SwiftFileBackend extends FileBackendStore {
 		} catch ( CloudFilesException $e ) { // some other exception?
 			$this->handleException( $e, null, __METHOD__,
 				array( 'cont' => $fullCont, 'dir' => $dir ) );
+			throw new FileBackendError( "Got " . get_class( $e ) . " exception." );
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
 		return $dirs;
 	}
 
@@ -944,36 +989,52 @@ class SwiftFileBackend extends FileBackendStore {
 	/**
 	 * Do not call this function outside of SwiftFileBackendFileList
 	 *
-	 * @param $fullCont string Resolved container name
-	 * @param $dir string Resolved storage directory with no trailing slash
-	 * @param $after string|null Storage path of file to list items after
-	 * @param $limit integer Max number of items to list
-	 * @param $params Array Includes flag for 'topOnly'
-	 * @return Array List of relative paths of files under $dir
+	 * @param string $fullCont Resolved container name
+	 * @param string $dir Resolved storage directory with no trailing slash
+	 * @param string|null $after Storage path of file to list items after
+	 * @param integer $limit Max number of items to list
+	 * @param array $params Parameters for getDirectoryList()
+	 * @return Array List of resolved paths of files under $dir
+	 * @throws FileBackendError
 	 */
 	public function getFileListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
 		$files = array();
 		if ( $after === INF ) {
 			return $files; // nothing more
 		}
-		wfProfileIn( __METHOD__ . '-' . $this->name );
 
+		$section = new ProfileSection( __METHOD__ . '-' . $this->name );
 		try {
 			$container = $this->getContainer( $fullCont );
 			$prefix = ( $dir == '' ) ? null : "{$dir}/";
 			// Non-recursive: only list files right under $dir
 			if ( !empty( $params['topOnly'] ) ) { // files and dirs
-				$objects = $container->list_objects( $limit, $after, $prefix, null, '/' );
-				foreach ( $objects as $object ) {
-					if ( substr( $object, -1 ) !== '/' ) {
-						$files[] = $object; // directories end in '/'
+				if ( !empty( $params['adviseStat'] ) ) {
+					$limit = min( $limit, self::CACHE_CHEAP_SIZE );
+					// Note: get_objects() does not include directories
+					$objects = $this->loadObjectListing( $params, $dir,
+						$container->get_objects( $limit, $after, $prefix, null, '/' ) );
+					$files = $objects;
+				} else {
+					$objects = $container->list_objects( $limit, $after, $prefix, null, '/' );
+					foreach ( $objects as $object ) { // files and directories
+						if ( substr( $object, -1 ) !== '/' ) {
+							$files[] = $object; // directories end in '/'
+						}
 					}
 				}
 			// Recursive: list all files under $dir and its subdirs
 			} else { // files
-				$objects = $container->list_objects( $limit, $after, $prefix );
+				if ( !empty( $params['adviseStat'] ) ) {
+					$limit = min( $limit, self::CACHE_CHEAP_SIZE );
+					$objects = $this->loadObjectListing( $params, $dir,
+						$container->get_objects( $limit, $after, $prefix ) );
+				} else {
+					$objects = $container->list_objects( $limit, $after, $prefix );
+				}
 				$files = $objects;
 			}
+			// Page on the unfiltered object listing (what is returned may be filtered)
 			if ( count( $objects ) < $limit ) {
 				$after = INF; // avoid a second RTT
 			} else {
@@ -983,29 +1044,57 @@ class SwiftFileBackend extends FileBackendStore {
 		} catch ( CloudFilesException $e ) { // some other exception?
 			$this->handleException( $e, null, __METHOD__,
 				array( 'cont' => $fullCont, 'dir' => $dir ) );
+			throw new FileBackendError( "Got " . get_class( $e ) . " exception." );
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
 		return $files;
 	}
 
 	/**
-	 * @see FileBackendStore::doGetFileSha1base36()
-	 * @return bool
+	 * Load a list of objects that belong under $dir into stat cache
+	 * and return a list of the names of the objects in the same order.
+	 *
+	 * @param array $params Parameters for getDirectoryList()
+	 * @param string $dir Resolved container directory path
+	 * @param array $cfObjects List of CF_Object items
+	 * @return array List of object names
 	 */
+	private function loadObjectListing( array $params, $dir, array $cfObjects ) {
+		$names = array();
+		$storageDir = rtrim( $params['dir'], '/' );
+		$suffixStart = ( $dir === '' ) ? 0 : strlen( $dir ) + 1; // size of "path/to/dir/"
+		// Iterate over the list *backwards* as this primes the stat cache, which is LRU.
+		// If this fills the cache and the caller stats an uncached file before stating
+		// the ones on the listing, there would be zero cache hits if this went forwards.
+		for ( end( $cfObjects ); key( $cfObjects ) !== null; prev( $cfObjects ) ) {
+			$object = current( $cfObjects );
+			$path = "{$storageDir}/" . substr( $object->name, $suffixStart );
+			$val = array(
+				// Convert dates like "Tue, 03 Jan 2012 22:01:04 GMT" to TS_MW
+				'mtime'  => wfTimestamp( TS_MW, $object->last_modified ),
+				'size'   => (int)$object->content_length,
+				'latest' => false // eventually consistent
+			);
+			$this->cheapCache->set( $path, 'stat', $val );
+			$names[] = $object->name;
+		}
+		return array_reverse( $names ); // keep the paths in original order
+	}
+
 	protected function doGetFileSha1base36( array $params ) {
 		$stat = $this->getFileStat( $params );
 		if ( $stat ) {
+			if ( !isset( $stat['sha1'] ) ) {
+				// Stat entries filled by file listings don't include SHA1
+				$this->clearCache( array( $params['src'] ) );
+				$stat = $this->getFileStat( $params );
+			}
 			return $stat['sha1'];
 		} else {
 			return false;
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doStreamFile()
-	 * @return Status
-	 */
 	protected function doStreamFile( array $params ) {
 		$status = Status::newGood();
 
@@ -1037,51 +1126,120 @@ class SwiftFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::getLocalCopy()
-	 * @return null|TempFSFile
-	 */
-	public function getLocalCopy( array $params ) {
-		list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
-		if ( $srcRel === null ) {
-			return null;
-		}
+	protected function doGetLocalCopyMulti( array $params ) {
+		$tmpFiles = array();
 
-		// Blindly create a tmp file and stream to it, catching any exception if the file does
-		// not exist. Also, doing a stat here will cause infinite loops when filling metadata.
-		$tmpFile = null;
-		try {
-			$sContObj = $this->getContainer( $srcCont );
-			$obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
-			// Get source file extension
-			$ext = FileBackend::extensionFromPath( $srcRel );
-			// Create a new temporary file...
-			$tmpFile = TempFSFile::factory( 'localcopy_', $ext );
-			if ( $tmpFile ) {
-				$handle = fopen( $tmpFile->getPath(), 'wb' );
-				if ( $handle ) {
-					$obj->stream( $handle, $this->headersFromParams( $params ) );
-					fclose( $handle );
-				} else {
-					$tmpFile = null; // couldn't open temp file
+		$ep = array_diff_key( $params, array( 'srcs' => 1 ) ); // for error logging
+		// Blindly create tmp files and stream to them, catching any exception if the file does
+		// not exist. Doing a stat here is useless causes infinite loops in addMissingMetadata().
+		foreach ( array_chunk( $params['srcs'], $params['concurrency'] ) as $pathBatch ) {
+			$cfOps = array(); // (path => CF_Async_Op)
+
+			foreach ( $pathBatch as $path ) { // each path in this concurrent batch
+				list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
+				if ( $srcRel === null ) {
+					$tmpFiles[$path] = null;
+					continue;
+				}
+				$tmpFile = null;
+				try {
+					$sContObj = $this->getContainer( $srcCont );
+					$obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
+					// Get source file extension
+					$ext = FileBackend::extensionFromPath( $path );
+					// Create a new temporary file...
+					$tmpFile = TempFSFile::factory( 'localcopy_', $ext );
+					if ( $tmpFile ) {
+						$handle = fopen( $tmpFile->getPath(), 'wb' );
+						if ( $handle ) {
+							$headers = $this->headersFromParams( $params );
+							if ( count( $pathBatch ) > 1 ) {
+								$cfOps[$path] = $obj->stream_async( $handle, $headers );
+								$cfOps[$path]->_file_handle = $handle; // close this later
+							} else {
+								$obj->stream( $handle, $headers );
+								fclose( $handle );
+							}
+						} else {
+							$tmpFile = null;
+						}
+					}
+				} catch ( NoSuchContainerException $e ) {
+					$tmpFile = null;
+				} catch ( NoSuchObjectException $e ) {
+					$tmpFile = null;
+				} catch ( CloudFilesException $e ) { // some other exception?
+					$tmpFile = null;
+					$this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
 				}
+				$tmpFiles[$path] = $tmpFile;
+			}
+
+			$batch = new CF_Async_Op_Batch( $cfOps );
+			$cfOps = $batch->execute();
+			foreach ( $cfOps as $path => $cfOp ) {
+				try {
+					$cfOp->getLastResponse();
+				} catch ( NoSuchContainerException $e ) {
+					$tmpFiles[$path] = null;
+				} catch ( NoSuchObjectException $e ) {
+					$tmpFiles[$path] = null;
+				} catch ( CloudFilesException $e ) { // some other exception?
+					$tmpFiles[$path] = null;
+					$this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
+				}
+				fclose( $cfOp->_file_handle ); // close open handle
 			}
-		} catch ( NoSuchContainerException $e ) {
-			$tmpFile = null;
-		} catch ( NoSuchObjectException $e ) {
-			$tmpFile = null;
-		} catch ( CloudFilesException $e ) { // some other exception?
-			$tmpFile = null;
-			$this->handleException( $e, null, __METHOD__, $params );
 		}
 
-		return $tmpFile;
+		return $tmpFiles;
+	}
+
+	public function getFileHttpUrl( array $params ) {
+		if ( $this->swiftTempUrlKey != '' ||
+			( $this->rgwS3AccessKey != '' && $this->rgwS3SecretKey != '' ) )
+		{
+			list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
+			if ( $srcRel === null ) {
+				return null; // invalid path
+			}
+			try {
+				$ttl = isset( $params['ttl'] ) ? $params['ttl'] : 86400;
+				$sContObj = $this->getContainer( $srcCont );
+				$obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
+				if ( $this->swiftTempUrlKey != '' ) {
+					return $obj->get_temp_url( $this->swiftTempUrlKey, $ttl, "GET" );
+				} else { // give S3 API URL for rgw
+					$expires = time() + $ttl;
+					// Path for signature starts with the bucket
+					$spath = '/' . rawurlencode( $srcCont ) . '/' .
+						str_replace( '%2F', '/', rawurlencode( $srcRel ) );
+					// Calculate the hash
+					$signature = base64_encode( hash_hmac(
+						'sha1',
+						"GET\n\n\n{$expires}\n{$spath}",
+						$this->rgwS3SecretKey,
+						true // raw
+					) );
+					// See http://s3.amazonaws.com/doc/s3-developer-guide/RESTAuthentication.html.
+					// Note: adding a newline for empty CanonicalizedAmzHeaders does not work.
+					return wfAppendQuery(
+						str_replace( '/swift/v1', '', // S3 API is the rgw default
+							$sContObj->cfs_http->getStorageUrl() . $spath ),
+						array(
+							'Signature' => $signature,
+							'Expires' => $expires,
+							'AWSAccessKeyId' => $this->rgwS3AccessKey )
+					);
+				}
+			} catch ( NoSuchContainerException $e ) {
+			} catch ( CloudFilesException $e ) { // some other exception?
+				$this->handleException( $e, null, __METHOD__, $params );
+			}
+		}
+		return null;
 	}
 
-	/**
-	 * @see FileBackendStore::directoriesAreVirtual()
-	 * @return bool
-	 */
 	protected function directoriesAreVirtual() {
 		return true;
 	}
@@ -1091,7 +1249,7 @@ class SwiftFileBackend extends FileBackendStore {
 	 * on a FileBackend params array, e.g. that of getLocalCopy().
 	 * $params is currently only checked for a 'latest' flag.
 	 *
-	 * @param $params Array
+	 * @param array $params
 	 * @return Array
 	 */
 	protected function headersFromParams( array $params ) {
@@ -1102,10 +1260,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $hdrs;
 	}
 
-	/**
-	 * @see FileBackendStore::doExecuteOpHandlesInternal()
-	 * @return Array List of corresponding Status objects
-	 */
 	protected function doExecuteOpHandlesInternal( array $fileOpHandles ) {
 		$statuses = array();
 
@@ -1118,8 +1272,8 @@ class SwiftFileBackend extends FileBackendStore {
 		$cfOps = $batch->execute();
 		foreach ( $cfOps as $index => $cfOp ) {
 			$status = Status::newGood();
+			$function = '_getResponse' . $fileOpHandles[$index]->call;
 			try { // catch exceptions; update status
-				$function = '_getResponse' . $fileOpHandles[$index]->call;
 				$this->$function( $cfOp, $status, $fileOpHandles[$index]->params );
 				$this->purgeCDNCache( $fileOpHandles[$index]->affectedObjects );
 			} catch ( CloudFilesException $e ) { // some other exception?
@@ -1137,12 +1291,12 @@ class SwiftFileBackend extends FileBackendStore {
 	 *
 	 * $readGrps is a list of the possible criteria for a request to have
 	 * access to read a container. Each item is one of the following formats:
-	 *   - account:user       : Grants access if the request is by the given user
-	 *   - .r:<regex>         : Grants access if the request is from a referrer host that
-	 *                          matches the expression and the request is not for a listing.
-	 *                          Setting this to '*' effectively makes a container public.
-	 *   - .rlistings:<regex> : Grants access if the request is from a referrer host that
-	 *                          matches the expression and the request for a listing.
+	 *   - account:user        : Grants access if the request is by the given user
+	 *   - ".r:<regex>"        : Grants access if the request is from a referrer host that
+	 *                           matches the expression and the request is not for a listing.
+	 *                           Setting this to '*' effectively makes a container public.
+	 *   -".rlistings:<regex>" : Grants access if the request is from a referrer host that
+	 *                           matches the expression and the request is for a listing.
 	 *
 	 * $writeGrps is a list of the possible criteria for a request to have
 	 * access to write to a container. Each item is of the following format:
@@ -1153,9 +1307,9 @@ class SwiftFileBackend extends FileBackendStore {
 	 * In general, we don't allow listings to end-users. It's not useful, isn't well-defined
 	 * (lists are truncated to 10000 item with no way to page), and is just a performance risk.
 	 *
-	 * @param $contObj CF_Container Swift container
-	 * @param $readGrps Array List of read access routes
-	 * @param $writeGrps Array List of write access routes
+	 * @param CF_Container $contObj Swift container
+	 * @param array $readGrps List of read access routes
+	 * @param array $writeGrps List of write access routes
 	 * @return Status
 	 */
 	protected function setContainerAccess(
@@ -1178,7 +1332,7 @@ class SwiftFileBackend extends FileBackendStore {
 	 * Purge the CDN cache of affected objects if CDN caching is enabled.
 	 * This is for Rackspace/Akamai CDNs.
 	 *
-	 * @param $objects Array List of CF_Object items
+	 * @param array $objects List of CF_Object items
 	 * @return void
 	 */
 	public function purgeCDNCache( array $objects ) {
@@ -1199,8 +1353,9 @@ class SwiftFileBackend extends FileBackendStore {
 	/**
 	 * Get an authenticated connection handle to the Swift proxy
 	 *
-	 * @return CF_Connection|bool False on failure
 	 * @throws CloudFilesException
+	 * @throws CloudFilesException|Exception
+	 * @return CF_Connection|bool False on failure
 	 */
 	protected function getConnection() {
 		if ( $this->connException instanceof CloudFilesException ) {
@@ -1222,12 +1377,12 @@ class SwiftFileBackend extends FileBackendStore {
 			if ( is_array( $creds ) ) { // cache hit
 				$this->auth->load_cached_credentials(
 					$creds['auth_token'], $creds['storage_url'], $creds['cdnm_url'] );
-				$this->sessionStarted = time() - ceil( $this->authTTL/2 ); // skew for worst case
+				$this->sessionStarted = time() - ceil( $this->authTTL / 2 ); // skew for worst case
 			} else { // cache miss
 				try {
 					$this->auth->authenticate();
 					$creds = $this->auth->export_credentials();
-					$this->srvCache->add( $cacheKey, $creds, ceil( $this->authTTL/2 ) ); // cache
+					$this->srvCache->add( $cacheKey, $creds, ceil( $this->authTTL / 2 ) ); // cache
 					$this->sessionStarted = time();
 				} catch ( CloudFilesException $e ) {
 					$this->connException = $e; // don't keep re-trying
@@ -1251,6 +1406,7 @@ class SwiftFileBackend extends FileBackendStore {
 	protected function closeConnection() {
 		if ( $this->conn ) {
 			$this->conn->close(); // close active cURL handles in CF_Http object
+			$this->conn = null;
 			$this->sessionStarted = 0;
 			$this->connContainerCache->clear();
 		}
@@ -1259,7 +1415,7 @@ class SwiftFileBackend extends FileBackendStore {
 	/**
 	 * Get the cache key for a container
 	 *
-	 * @param $username string
+	 * @param string $username
 	 * @return string
 	 */
 	private function getCredsCacheKey( $username ) {
@@ -1267,18 +1423,11 @@ class SwiftFileBackend extends FileBackendStore {
 	}
 
 	/**
-	 * @see FileBackendStore::doClearCache()
-	 */
-	protected function doClearCache( array $paths = null ) {
-		$this->connContainerCache->clear(); // clear container object cache
-	}
-
-	/**
 	 * Get a Swift container object, possibly from process cache.
 	 * Use $reCache if the file count or byte count is needed.
 	 *
-	 * @param $container string Container name
-	 * @param $bypassCache bool Bypass all caches and load from Swift
+	 * @param string $container Container name
+	 * @param bool $bypassCache Bypass all caches and load from Swift
 	 * @return CF_Container
 	 * @throws CloudFilesException
 	 */
@@ -1305,7 +1454,7 @@ class SwiftFileBackend extends FileBackendStore {
 	/**
 	 * Create a Swift container
 	 *
-	 * @param $container string Container name
+	 * @param string $container Container name
 	 * @return CF_Container
 	 * @throws CloudFilesException
 	 */
@@ -1319,7 +1468,7 @@ class SwiftFileBackend extends FileBackendStore {
 	/**
 	 * Delete a Swift container
 	 *
-	 * @param $container string Container name
+	 * @param string $container Container name
 	 * @return void
 	 * @throws CloudFilesException
 	 */
@@ -1329,10 +1478,6 @@ class SwiftFileBackend extends FileBackendStore {
 		$conn->delete_container( $container );
 	}
 
-	/**
-	 * @see FileBackendStore::doPrimeContainerCache()
-	 * @return void
-	 */
 	protected function doPrimeContainerCache( array $containerInfo ) {
 		try {
 			$conn = $this->getConnection(); // Swift proxy connection
@@ -1350,10 +1495,10 @@ class SwiftFileBackend extends FileBackendStore {
 	 * Log an unexpected exception for this backend.
 	 * This also sets the Status object to have a fatal error.
 	 *
-	 * @param $e Exception
-	 * @param $status Status|null
-	 * @param $func string
-	 * @param $params Array
+	 * @param Exception $e
+	 * @param Status $status|null
+	 * @param string $func
+	 * @param array $params
 	 * @return void
 	 */
 	protected function handleException( Exception $e, $status, $func, array $params ) {
@@ -1387,7 +1532,15 @@ class SwiftFileOpHandle extends FileBackendStoreOpHandle {
 	/** @var Array */
 	public $affectedObjects = array();
 
-	public function __construct( $backend, array $params, $call, CF_Async_Op $cfOp ) {
+	/**
+	 * @param SwiftFileBackend $backend
+	 * @param array $params
+	 * @param string $call
+	 * @param CF_Async_Op $cfOp
+	 */
+	public function __construct(
+		SwiftFileBackend $backend, array $params, $call, CF_Async_Op $cfOp
+	) {
 		$this->backend = $backend;
 		$this->params = $params;
 		$this->call = $call;
@@ -1419,10 +1572,10 @@ abstract class SwiftFileBackendList implements Iterator {
 	const PAGE_SIZE = 9000; // file listing buffer size
 
 	/**
-	 * @param $backend SwiftFileBackend
-	 * @param $fullCont string Resolved container name
-	 * @param $dir string Resolved directory relative to container
-	 * @param $params Array
+	 * @param SwiftFileBackend $backend
+	 * @param string $fullCont Resolved container name
+	 * @param string $dir Resolved directory relative to container
+	 * @param array $params
 	 */
 	public function __construct( SwiftFileBackend $backend, $fullCont, $dir, array $params ) {
 		$this->backend = $backend;
@@ -1491,12 +1644,12 @@ abstract class SwiftFileBackendList implements Iterator {
 	/**
 	 * Get the given list portion (page)
 	 *
-	 * @param $container string Resolved container name
-	 * @param $dir string Resolved path relative to container
-	 * @param $after string|null
-	 * @param $limit integer
-	 * @param $params Array
-	 * @return Traversable|Array|null Returns null on failure
+	 * @param string $container Resolved container name
+	 * @param string $dir Resolved path relative to container
+	 * @param string $after|null
+	 * @param integer $limit
+	 * @param array $params
+	 * @return Traversable|Array
 	 */
 	abstract protected function pageFromList( $container, $dir, &$after, $limit, array $params );
 }
@@ -1515,7 +1668,7 @@ class SwiftFileBackendDirList extends SwiftFileBackendList {
 
 	/**
 	 * @see SwiftFileBackendList::pageFromList()
-	 * @return Array|null
+	 * @return Array
 	 */
 	protected function pageFromList( $container, $dir, &$after, $limit, array $params ) {
 		return $this->backend->getDirListPageInternal( $container, $dir, $after, $limit, $params );
@@ -1536,7 +1689,7 @@ class SwiftFileBackendFileList extends SwiftFileBackendList {
 
 	/**
 	 * @see SwiftFileBackendList::pageFromList()
-	 * @return Array|null
+	 * @return Array
 	 */
 	protected function pageFromList( $container, $dir, &$after, $limit, array $params ) {
 		return $this->backend->getFileListPageInternal( $container, $dir, $after, $limit, $params );
diff --git a/includes/filebackend/TempFSFile.php b/includes/filebackend/TempFSFile.php
index 5032bf68..8266e420 100644
--- a/includes/filebackend/TempFSFile.php
+++ b/includes/filebackend/TempFSFile.php
@@ -37,8 +37,8 @@ class TempFSFile extends FSFile {
 	 * Make a new temporary file on the file system.
 	 * Temporary files may be purged when the file object falls out of scope.
 	 *
-	 * @param $prefix string
-	 * @param $extension string
+	 * @param string $prefix
+	 * @param string $extension
 	 * @return TempFSFile|null
 	 */
 	public static function factory( $prefix, $extension = '' ) {
@@ -81,31 +81,38 @@ class TempFSFile extends FSFile {
 	/**
 	 * Clean up the temporary file only after an object goes out of scope
 	 *
-	 * @param $object Object
-	 * @return void
+	 * @param Object $object
+	 * @return TempFSFile This object
 	 */
 	public function bind( $object ) {
 		if ( is_object( $object ) ) {
+			if ( !isset( $object->tempFSFileReferences ) ) {
+				// Init first since $object might use __get() and return only a copy variable
+				$object->tempFSFileReferences = array();
+			}
 			$object->tempFSFileReferences[] = $this;
 		}
+		return $this;
 	}
 
 	/**
 	 * Set flag to not clean up after the temporary file
 	 *
-	 * @return void
+	 * @return TempFSFile This object
 	 */
 	public function preserve() {
 		$this->canDelete = false;
+		return $this;
 	}
 
 	/**
 	 * Set flag clean up after the temporary file
 	 *
-	 * @return void
+	 * @return TempFSFile This object
 	 */
 	public function autocollect() {
 		$this->canDelete = true;
+		return $this;
 	}
 
 	/**
diff --git a/includes/filebackend/filejournal/DBFileJournal.php b/includes/filebackend/filejournal/DBFileJournal.php
index f6268c25..9250aa5e 100644
--- a/includes/filebackend/filejournal/DBFileJournal.php
+++ b/includes/filebackend/filejournal/DBFileJournal.php
@@ -65,16 +65,19 @@ class DBFileJournal extends FileJournal {
 		foreach ( $entries as $entry ) {
 			$data[] = array(
 				'fj_batch_uuid' => $batchId,
-				'fj_backend'    => $this->backend,
-				'fj_op'         => $entry['op'],
-				'fj_path'       => $entry['path'],
-				'fj_new_sha1'   => $entry['newSha1'],
-				'fj_timestamp'  => $dbw->timestamp( $now )
+				'fj_backend' => $this->backend,
+				'fj_op' => $entry['op'],
+				'fj_path' => $entry['path'],
+				'fj_new_sha1' => $entry['newSha1'],
+				'fj_timestamp' => $dbw->timestamp( $now )
 			);
 		}
 
 		try {
 			$dbw->insert( 'filejournal', $data, __METHOD__ );
+			if ( mt_rand( 0, 99 ) == 0 ) {
+				$this->purgeOldLogs(); // occasionally delete old logs
+			}
 		} catch ( DBError $e ) {
 			$status->fatal( 'filejournal-fail-dbquery', $this->backend );
 			return $status;
@@ -84,6 +87,35 @@ class DBFileJournal extends FileJournal {
 	}
 
 	/**
+	 * @see FileJournal::doGetCurrentPosition()
+	 * @return integer|false
+	 */
+	protected function doGetCurrentPosition() {
+		$dbw = $this->getMasterDB();
+
+		return $dbw->selectField( 'filejournal', 'MAX(fj_id)',
+			array( 'fj_backend' => $this->backend ),
+			__METHOD__
+		);
+	}
+
+	/**
+	 * @see FileJournal::doGetPositionAtTime()
+	 * @param $time integer|string timestamp
+	 * @return integer|false
+	 */
+	protected function doGetPositionAtTime( $time ) {
+		$dbw = $this->getMasterDB();
+
+		$encTimestamp = $dbw->addQuotes( $dbw->timestamp( $time ) );
+		return $dbw->selectField( 'filejournal', 'fj_id',
+			array( 'fj_backend' => $this->backend, "fj_timestamp <= $encTimestamp" ),
+			__METHOD__,
+			array( 'ORDER BY' => 'fj_timestamp DESC' )
+		);
+	}
+
+	/**
 	 * @see FileJournal::doGetChangeEntries()
 	 * @return Array
 	 * @throws DBError
diff --git a/includes/filebackend/filejournal/FileJournal.php b/includes/filebackend/filejournal/FileJournal.php
index ce029bbe..a1b7a459 100644
--- a/includes/filebackend/filejournal/FileJournal.php
+++ b/includes/filebackend/filejournal/FileJournal.php
@@ -54,7 +54,7 @@ abstract class FileJournal {
 	 * Create an appropriate FileJournal object from config
 	 *
 	 * @param $config Array
-	 * @param $backend string A registered file backend name
+	 * @param string $backend A registered file backend name
 	 * @throws MWException
 	 * @return FileJournal
 	 */
@@ -85,13 +85,13 @@ abstract class FileJournal {
 	/**
 	 * Log changes made by a batch file operation.
 	 * $entries is an array of log entries, each of which contains:
-	 *     op      : Basic operation name (create, store, copy, delete)
+	 *     op      : Basic operation name (create, update, delete)
 	 *     path    : The storage path of the file
 	 *     newSha1 : The final base 36 SHA-1 of the file
 	 * Note that 'false' should be used as the SHA-1 for non-existing files.
 	 *
-	 * @param $entries Array List of file operations (each an array of parameters)
-	 * @param $batchId string UUID string that identifies the operation batch
+	 * @param array $entries List of file operations (each an array of parameters)
+	 * @param string $batchId UUID string that identifies the operation batch
 	 * @return Status
 	 */
 	final public function logChangeBatch( array $entries, $batchId ) {
@@ -104,13 +104,45 @@ abstract class FileJournal {
 	/**
 	 * @see FileJournal::logChangeBatch()
 	 *
-	 * @param $entries Array List of file operations (each an array of parameters)
-	 * @param $batchId string UUID string that identifies the operation batch
+	 * @param array $entries List of file operations (each an array of parameters)
+	 * @param string $batchId UUID string that identifies the operation batch
 	 * @return Status
 	 */
 	abstract protected function doLogChangeBatch( array $entries, $batchId );
 
 	/**
+	 * Get the position ID of the latest journal entry
+	 *
+	 * @return integer|false
+	 */
+	final public function getCurrentPosition() {
+		return $this->doGetCurrentPosition();
+	}
+
+	/**
+	 * @see FileJournal::getCurrentPosition()
+	 * @return integer|false
+	 */
+	abstract protected function doGetCurrentPosition();
+
+	/**
+	 * Get the position ID of the latest journal entry at some point in time
+	 *
+	 * @param $time integer|string timestamp
+	 * @return integer|false
+	 */
+	final public function getPositionAtTime( $time ) {
+		return $this->doGetPositionAtTime( $time );
+	}
+
+	/**
+	 * @see FileJournal::getPositionAtTime()
+	 * @param $time integer|string timestamp
+	 * @return integer|false
+	 */
+	abstract protected function doGetPositionAtTime( $time );
+
+	/**
 	 * Get an array of file change log entries.
 	 * A starting change ID and/or limit can be specified.
 	 *
@@ -169,7 +201,7 @@ abstract class FileJournal {
  */
 class NullFileJournal extends FileJournal {
 	/**
-	 * @see FileJournal::logChangeBatch()
+	 * @see FileJournal::doLogChangeBatch()
 	 * @param $entries array
 	 * @param $batchId string
 	 * @return Status
@@ -179,6 +211,23 @@ class NullFileJournal extends FileJournal {
 	}
 
 	/**
+	 * @see FileJournal::doGetCurrentPosition()
+	 * @return integer|false
+	 */
+	protected function doGetCurrentPosition() {
+		return false;
+	}
+
+	/**
+	 * @see FileJournal::doGetPositionAtTime()
+	 * @param $time integer|string timestamp
+	 * @return integer|false
+	 */
+	protected function doGetPositionAtTime( $time ) {
+		return false;
+	}
+
+	/**
 	 * @see FileJournal::doGetChangeEntries()
 	 * @return Array
 	 */
@@ -187,7 +236,7 @@ class NullFileJournal extends FileJournal {
 	}
 
 	/**
-	 * @see FileJournal::purgeOldLogs()
+	 * @see FileJournal::doPurgeOldLogs()
 	 * @return Status
 	 */
 	protected function doPurgeOldLogs() {
diff --git a/includes/filebackend/lockmanager/DBLockManager.php b/includes/filebackend/lockmanager/DBLockManager.php
index a8fe258b..3e934ba5 100644
--- a/includes/filebackend/lockmanager/DBLockManager.php
+++ b/includes/filebackend/lockmanager/DBLockManager.php
@@ -22,10 +22,9 @@
  */
 
 /**
- * Version of LockManager based on using DB table locks.
+ * Version of LockManager based on using named/row DB locks.
+ *
  * This is meant for multi-wiki systems that may share files.
- * All locks are blocking, so it might be useful to set a small
- * lock-wait timeout via server config to curtail deadlocks.
  *
  * All lock requests for a resource, identified by a hash string, will map
  * to one bucket. Each bucket maps to one or several peer DBs, each on their
@@ -37,7 +36,7 @@
  * @ingroup LockManager
  * @since 1.19
  */
-class DBLockManager extends QuorumLockManager {
+abstract class DBLockManager extends QuorumLockManager {
 	/** @var Array Map of DB names to server config */
 	protected $dbServers; // (DB name => server config array)
 	/** @var BagOStuff */
@@ -67,11 +66,12 @@ class DBLockManager extends QuorumLockManager {
 	 *                   each having an odd-numbered list of DB names (peers) as values.
 	 *                   Any DB named 'localDBMaster' will automatically use the DB master
 	 *                   settings for this wiki (without the need for a dbServers entry).
+	 *                   Only use 'localDBMaster' if the domain is a valid wiki ID.
 	 *   - lockExpiry  : Lock timeout (seconds) for dropped connections. [optional]
 	 *                   This tells the DB server how long to wait before assuming
 	 *                   connection failure and releasing all the locks for a session.
 	 *
-	 * @param Array $config
+	 * @param array $config
 	 */
 	public function __construct( array $config ) {
 		parent::__construct( $config );
@@ -110,63 +110,17 @@ class DBLockManager extends QuorumLockManager {
 		$this->session = wfRandomString( 31 );
 	}
 
-	/**
-	 * Get a connection to a lock DB and acquire locks on $paths.
-	 * This does not use GET_LOCK() per http://bugs.mysql.com/bug.php?id=1118.
-	 *
-	 * @see QuorumLockManager::getLocksOnServer()
-	 * @return Status
-	 */
-	protected function getLocksOnServer( $lockSrv, array $paths, $type ) {
+	// @TODO: change this code to work in one batch
+	protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
 		$status = Status::newGood();
-
-		if ( $type == self::LOCK_EX ) { // writer locks
-			try {
-				$keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) );
-				# Build up values for INSERT clause
-				$data = array();
-				foreach ( $keys as $key ) {
-					$data[] = array( 'fle_key' => $key );
-				}
-				# Wait on any existing writers and block new ones if we get in
-				$db = $this->getConnection( $lockSrv ); // checked in isServerUp()
-				$db->insert( 'filelocks_exclusive', $data, __METHOD__ );
-			} catch ( DBError $e ) {
-				foreach ( $paths as $path ) {
-					$status->fatal( 'lockmanager-fail-acquirelock', $path );
-				}
-			}
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doGetLocksOnServer( $lockSrv, $paths, $type ) );
 		}
-
 		return $status;
 	}
 
-	/**
-	 * @see QuorumLockManager::freeLocksOnServer()
-	 * @return Status
-	 */
-	protected function freeLocksOnServer( $lockSrv, array $paths, $type ) {
-		return Status::newGood(); // not supported
-	}
-
-	/**
-	 * @see QuorumLockManager::releaseAllLocks()
-	 * @return Status
-	 */
-	protected function releaseAllLocks() {
-		$status = Status::newGood();
-
-		foreach ( $this->conns as $lockDb => $db ) {
-			if ( $db->trxLevel() ) { // in transaction
-				try {
-					$db->rollback( __METHOD__ ); // finish transaction and kill any rows
-				} catch ( DBError $e ) {
-					$status->fatal( 'lockmanager-fail-db-release', $lockDb );
-				}
-			}
-		}
-
-		return $status;
+	protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
+		return Status::newGood();
 	}
 
 	/**
@@ -197,8 +151,8 @@ class DBLockManager extends QuorumLockManager {
 		if ( !isset( $this->conns[$lockDb] ) ) {
 			$db = null;
 			if ( $lockDb === 'localDBMaster' ) {
-				$lb = wfGetLBFactory()->newMainLB();
-				$db = $lb->getConnection( DB_MASTER );
+				$lb = wfGetLBFactory()->getMainLB( $this->domain );
+				$db = $lb->getConnection( DB_MASTER, array(), $this->domain );
 			} elseif ( isset( $this->dbServers[$lockDb] ) ) {
 				$config = $this->dbServers[$lockDb];
 				$db = DatabaseBase::factory( $config['type'], $config );
@@ -274,14 +228,8 @@ class DBLockManager extends QuorumLockManager {
 	 * Make sure remaining locks get cleared for sanity
 	 */
 	function __destruct() {
+		$this->releaseAllLocks();
 		foreach ( $this->conns as $db ) {
-			if ( $db->trxLevel() ) { // in transaction
-				try {
-					$db->rollback( __METHOD__ ); // finish transaction and kill any rows
-				} catch ( DBError $e ) {
-					// oh well
-				}
-			}
 			$db->close();
 		}
 	}
@@ -317,31 +265,42 @@ class MySqlLockManager extends DBLockManager {
 	 * @see DBLockManager::getLocksOnServer()
 	 * @return Status
 	 */
-	protected function getLocksOnServer( $lockSrv, array $paths, $type ) {
+	protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
 		$status = Status::newGood();
 
 		$db = $this->getConnection( $lockSrv ); // checked in isServerUp()
-		$keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) );
+
+		$keys = array(); // list of hash keys for the paths
+		$data = array(); // list of rows to insert
+		$checkEXKeys = array(); // list of hash keys that this has no EX lock on
 		# Build up values for INSERT clause
-		$data = array();
-		foreach ( $keys as $key ) {
+		foreach ( $paths as $path ) {
+			$key = $this->sha1Base36Absolute( $path );
+			$keys[] = $key;
 			$data[] = array( 'fls_key' => $key, 'fls_session' => $this->session );
+			if ( !isset( $this->locksHeld[$path][self::LOCK_EX] ) ) {
+				$checkEXKeys[] = $key;
+			}
 		}
-		# Block new writers...
+
+		# Block new writers (both EX and SH locks leave entries here)...
 		$db->insert( 'filelocks_shared', $data, __METHOD__, array( 'IGNORE' ) );
 		# Actually do the locking queries...
 		if ( $type == self::LOCK_SH ) { // reader locks
+			$blocked = false;
 			# Bail if there are any existing writers...
-			$blocked = $db->selectField( 'filelocks_exclusive', '1',
-				array( 'fle_key' => $keys ),
-				__METHOD__
-			);
-			# Prospective writers that haven't yet updated filelocks_exclusive
-			# will recheck filelocks_shared after doing so and bail due to our entry.
+			if ( count( $checkEXKeys ) ) {
+				$blocked = $db->selectField( 'filelocks_exclusive', '1',
+					array( 'fle_key' => $checkEXKeys ),
+					__METHOD__
+				);
+			}
+			# Other prospective writers that haven't yet updated filelocks_exclusive
+			# will recheck filelocks_shared after doing so and bail due to this entry.
 		} else { // writer locks
 			$encSession = $db->addQuotes( $this->session );
 			# Bail if there are any existing writers...
-			# The may detect readers, but the safe check for them is below.
+			# This may detect readers, but the safe check for them is below.
 			# Note: if two writers come at the same time, both bail :)
 			$blocked = $db->selectField( 'filelocks_shared', '1',
 				array( 'fls_key' => $keys, "fls_session != $encSession" ),
@@ -371,4 +330,103 @@ class MySqlLockManager extends DBLockManager {
 
 		return $status;
 	}
+
+	/**
+	 * @see QuorumLockManager::releaseAllLocks()
+	 * @return Status
+	 */
+	protected function releaseAllLocks() {
+		$status = Status::newGood();
+
+		foreach ( $this->conns as $lockDb => $db ) {
+			if ( $db->trxLevel() ) { // in transaction
+				try {
+					$db->rollback( __METHOD__ ); // finish transaction and kill any rows
+				} catch ( DBError $e ) {
+					$status->fatal( 'lockmanager-fail-db-release', $lockDb );
+				}
+			}
+		}
+
+		return $status;
+	}
+}
+
+/**
+ * PostgreSQL version of DBLockManager that supports shared locks.
+ * All locks are non-blocking, which avoids deadlocks.
+ *
+ * @ingroup LockManager
+ */
+class PostgreSqlLockManager extends DBLockManager {
+	/** @var Array Mapping of lock types to the type actually used */
+	protected $lockTypeMap = array(
+		self::LOCK_SH => self::LOCK_SH,
+		self::LOCK_UW => self::LOCK_SH,
+		self::LOCK_EX => self::LOCK_EX
+	);
+
+	protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
+		$status = Status::newGood();
+		if ( !count( $paths ) ) {
+			return $status; // nothing to lock
+		}
+
+		$db = $this->getConnection( $lockSrv ); // checked in isServerUp()
+		$bigints = array_unique( array_map(
+			function( $key ) {
+				return wfBaseConvert( substr( $key, 0, 15 ), 16, 10 );
+			},
+			array_map( array( $this, 'sha1Base16Absolute' ), $paths )
+		) );
+
+		// Try to acquire all the locks...
+		$fields = array();
+		foreach ( $bigints as $bigint ) {
+			$fields[] = ( $type == self::LOCK_SH )
+				? "pg_try_advisory_lock_shared({$db->addQuotes( $bigint )}) AS K$bigint"
+				: "pg_try_advisory_lock({$db->addQuotes( $bigint )}) AS K$bigint";
+		}
+		$res = $db->query( 'SELECT ' . implode( ', ', $fields ), __METHOD__ );
+		$row = (array)$res->fetchObject();
+
+		if ( in_array( 'f', $row ) ) {
+			// Release any acquired locks if some could not be acquired...
+			$fields = array();
+			foreach ( $row as $kbigint => $ok ) {
+				if ( $ok === 't' ) { // locked
+					$bigint = substr( $kbigint, 1 ); // strip off the "K"
+					$fields[] = ( $type == self::LOCK_SH )
+						? "pg_advisory_unlock_shared({$db->addQuotes( $bigint )})"
+						: "pg_advisory_unlock({$db->addQuotes( $bigint )})";
+				}
+			}
+			if ( count( $fields ) ) {
+				$db->query( 'SELECT ' . implode( ', ', $fields ), __METHOD__ );
+			}
+			foreach ( $paths as $path ) {
+				$status->fatal( 'lockmanager-fail-acquirelock', $path );
+			}
+		}
+
+		return $status;
+	}
+
+	/**
+	 * @see QuorumLockManager::releaseAllLocks()
+	 * @return Status
+	 */
+	protected function releaseAllLocks() {
+		$status = Status::newGood();
+
+		foreach ( $this->conns as $lockDb => $db ) {
+			try {
+				$db->query( "SELECT pg_advisory_unlock_all()", __METHOD__ );
+			} catch ( DBError $e ) {
+				$status->fatal( 'lockmanager-fail-db-release', $lockDb );
+			}
+		}
+
+		return $status;
+	}
 }
diff --git a/includes/filebackend/lockmanager/FSLockManager.php b/includes/filebackend/lockmanager/FSLockManager.php
index 9a6206fd..eacba704 100644
--- a/includes/filebackend/lockmanager/FSLockManager.php
+++ b/includes/filebackend/lockmanager/FSLockManager.php
@@ -43,7 +43,7 @@ class FSLockManager extends LockManager {
 
 	protected $lockDir; // global dir for all servers
 
-	/** @var Array Map of (locked key => lock type => lock file handle) */
+	/** @var Array Map of (locked key => lock file handle) */
 	protected $handles = array();
 
 	/**
@@ -115,12 +115,16 @@ class FSLockManager extends LockManager {
 		} elseif ( isset( $this->locksHeld[$path][self::LOCK_EX] ) ) {
 			$this->locksHeld[$path][$type] = 1;
 		} else {
-			wfSuppressWarnings();
-			$handle = fopen( $this->getLockPath( $path ), 'a+' );
-			wfRestoreWarnings();
-			if ( !$handle ) { // lock dir missing?
-				wfMkdirParents( $this->lockDir );
-				$handle = fopen( $this->getLockPath( $path ), 'a+' ); // try again
+			if ( isset( $this->handles[$path] ) ) {
+				$handle = $this->handles[$path];
+			} else {
+				wfSuppressWarnings();
+				$handle = fopen( $this->getLockPath( $path ), 'a+' );
+				wfRestoreWarnings();
+				if ( !$handle ) { // lock dir missing?
+					wfMkdirParents( $this->lockDir );
+					$handle = fopen( $this->getLockPath( $path ), 'a+' ); // try again
+				}
 			}
 			if ( $handle ) {
 				// Either a shared or exclusive lock
@@ -128,7 +132,7 @@ class FSLockManager extends LockManager {
 				if ( flock( $handle, $lock | LOCK_NB ) ) {
 					// Record this lock as active
 					$this->locksHeld[$path][$type] = 1;
-					$this->handles[$path][$type] = $handle;
+					$this->handles[$path] = $handle;
 				} else {
 					fclose( $handle );
 					$status->fatal( 'lockmanager-fail-acquirelock', $path );
@@ -160,24 +164,13 @@ class FSLockManager extends LockManager {
 			--$this->locksHeld[$path][$type];
 			if ( $this->locksHeld[$path][$type] <= 0 ) {
 				unset( $this->locksHeld[$path][$type] );
-				// If a LOCK_SH comes in while we have a LOCK_EX, we don't
-				// actually add a handler, so check for handler existence.
-				if ( isset( $this->handles[$path][$type] ) ) {
-					if ( $type === self::LOCK_EX
-						&& isset( $this->locksHeld[$path][self::LOCK_SH] )
-						&& !isset( $this->handles[$path][self::LOCK_SH] ) )
-					{
-						// EX lock came first: move this handle to the SH one
-						$this->handles[$path][self::LOCK_SH] = $this->handles[$path][$type];
-					} else {
-						// Mark this handle to be unlocked and closed
-						$handlesToClose[] = $this->handles[$path][$type];
-					}
-					unset( $this->handles[$path][$type] );
-				}
 			}
 			if ( !count( $this->locksHeld[$path] ) ) {
 				unset( $this->locksHeld[$path] ); // no locks on this path
+				if ( isset( $this->handles[$path] ) ) {
+					$handlesToClose[] = $this->handles[$path];
+					unset( $this->handles[$path] );
+				}
 			}
 			// Unlock handles to release locks and delete
 			// any lock files that end up with no locks on them...
@@ -237,8 +230,7 @@ class FSLockManager extends LockManager {
 	 * @return string
 	 */
 	protected function getLockPath( $path ) {
-		$hash = self::sha1Base36( $path );
-		return "{$this->lockDir}/{$hash}.lock";
+		return "{$this->lockDir}/{$this->sha1Base36Absolute( $path )}.lock";
 	}
 
 	/**
diff --git a/includes/filebackend/lockmanager/LSLockManager.php b/includes/filebackend/lockmanager/LSLockManager.php
index 89428182..97de8dca 100644
--- a/includes/filebackend/lockmanager/LSLockManager.php
+++ b/includes/filebackend/lockmanager/LSLockManager.php
@@ -66,7 +66,7 @@ class LSLockManager extends QuorumLockManager {
 	 *                    each having an odd-numbered list of server names (peers) as values.
 	 *   - connTimeout  : Lock server connection attempt timeout. [optional]
 	 *
-	 * @param Array $config
+	 * @param array $config
 	 */
 	public function __construct( array $config ) {
 		parent::__construct( $config );
@@ -94,7 +94,7 @@ class LSLockManager extends QuorumLockManager {
 
 		// Send out the command and get the response...
 		$type = ( $type == self::LOCK_SH ) ? 'SH' : 'EX';
-		$keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) );
+		$keys = array_unique( array_map( array( $this, 'sha1Base36Absolute' ), $paths ) );
 		$response = $this->sendCommand( $lockSrv, 'ACQUIRE', $type, $keys );
 
 		if ( $response !== 'ACQUIRED' ) {
@@ -115,7 +115,7 @@ class LSLockManager extends QuorumLockManager {
 
 		// Send out the command and get the response...
 		$type = ( $type == self::LOCK_SH ) ? 'SH' : 'EX';
-		$keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) );
+		$keys = array_unique( array_map( array( $this, 'sha1Base36Absolute' ), $paths ) );
 		$response = $this->sendCommand( $lockSrv, 'RELEASE', $type, $keys );
 
 		if ( $response !== 'RELEASED' ) {
@@ -169,7 +169,7 @@ class LSLockManager extends QuorumLockManager {
 		$authKey = $this->lockServers[$lockSrv]['authKey'];
 		// Build of the command as a flat string...
 		$values = implode( '|', $values );
-		$key = sha1( $this->session . $action . $type . $values . $authKey );
+		$key = hash_hmac( 'sha1', "{$this->session}\n{$action}\n{$type}\n{$values}", $authKey );
 		// Send out the command...
 		if ( fwrite( $conn, "{$this->session}:$key:$action:$type:$values\n" ) === false ) {
 			return false;
diff --git a/includes/filebackend/lockmanager/LockManager.php b/includes/filebackend/lockmanager/LockManager.php
index 07853f87..dad8a624 100644
--- a/includes/filebackend/lockmanager/LockManager.php
+++ b/includes/filebackend/lockmanager/LockManager.php
@@ -53,7 +53,10 @@ abstract class LockManager {
 	/** @var Array Map of (resource path => lock type => count) */
 	protected $locksHeld = array();
 
-	/* Lock types; stronger locks have higher values */
+	protected $domain; // string; domain (usually wiki ID)
+	protected $lockTTL; // integer; maximum time locks can be held
+
+	/** Lock types; stronger locks have higher values */
 	const LOCK_SH = 1; // shared lock (for reads)
 	const LOCK_UW = 2; // shared lock (for reads used to write elsewhere)
 	const LOCK_EX = 3; // exclusive lock (for writes)
@@ -61,341 +64,185 @@ abstract class LockManager {
 	/**
 	 * Construct a new instance from configuration
 	 *
+	 * $config paramaters include:
+	 *   - domain  : Domain (usually wiki ID) that all resources are relative to [optional]
+	 *   - lockTTL : Age (in seconds) at which resource locks should expire.
+	 *               This only applies if locks are not tied to a connection/process.
+	 *
 	 * @param $config Array
 	 */
-	public function __construct( array $config ) {}
+	public function __construct( array $config ) {
+		$this->domain = isset( $config['domain'] ) ? $config['domain'] : wfWikiID();
+		if ( isset( $config['lockTTL'] ) ) {
+			$this->lockTTL = max( 1, $config['lockTTL'] );
+		} elseif ( PHP_SAPI === 'cli' ) {
+			$this->lockTTL = 2 * 3600;
+		} else {
+			$met = ini_get( 'max_execution_time' ); // this is 0 in CLI mode
+			$this->lockTTL = max( 5 * 60, 2 * (int)$met );
+		}
+	}
 
 	/**
 	 * Lock the resources at the given abstract paths
 	 *
-	 * @param $paths Array List of resource names
+	 * @param array $paths List of resource names
 	 * @param $type integer LockManager::LOCK_* constant
+	 * @param integer $timeout Timeout in seconds (0 means non-blocking) (since 1.21)
 	 * @return Status
 	 */
-	final public function lock( array $paths, $type = self::LOCK_EX ) {
-		wfProfileIn( __METHOD__ );
-		$status = $this->doLock( array_unique( $paths ), $this->lockTypeMap[$type] );
-		wfProfileOut( __METHOD__ );
-		return $status;
+	final public function lock( array $paths, $type = self::LOCK_EX, $timeout = 0 ) {
+		return $this->lockByType( array( $type => $paths ), $timeout );
 	}
 
 	/**
-	 * Unlock the resources at the given abstract paths
+	 * Lock the resources at the given abstract paths
 	 *
-	 * @param $paths Array List of storage paths
-	 * @param $type integer LockManager::LOCK_* constant
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
+	 * @param integer $timeout Timeout in seconds (0 means non-blocking) (since 1.21)
 	 * @return Status
+	 * @since 1.22
 	 */
-	final public function unlock( array $paths, $type = self::LOCK_EX ) {
+	final public function lockByType( array $pathsByType, $timeout = 0 ) {
 		wfProfileIn( __METHOD__ );
-		$status = $this->doUnlock( array_unique( $paths ), $this->lockTypeMap[$type] );
+		$status = Status::newGood();
+		$pathsByType = $this->normalizePathsByType( $pathsByType );
+		$msleep = array( 0, 50, 100, 300, 500 ); // retry backoff times
+		$start = microtime( true );
+		do {
+			$status = $this->doLockByType( $pathsByType );
+			$elapsed = microtime( true ) - $start;
+			if ( $status->isOK() || $elapsed >= $timeout || $elapsed < 0 ) {
+				break; // success, timeout, or clock set back
+			}
+			usleep( 1e3 * ( next( $msleep ) ?: 1000 ) ); // use 1 sec after enough times
+			$elapsed = microtime( true ) - $start;
+		} while ( $elapsed < $timeout && $elapsed >= 0 );
 		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
 	/**
-	 * Get the base 36 SHA-1 of a string, padded to 31 digits
+	 * Unlock the resources at the given abstract paths
 	 *
-	 * @param $path string
-	 * @return string
+	 * @param array $paths List of paths
+	 * @param $type integer LockManager::LOCK_* constant
+	 * @return Status
 	 */
-	final protected static function sha1Base36( $path ) {
-		return wfBaseConvert( sha1( $path ), 16, 36, 31 );
+	final public function unlock( array $paths, $type = self::LOCK_EX ) {
+		return $this->unlockByType( array( $type => $paths ) );
 	}
 
 	/**
-	 * Lock resources with the given keys and lock type
+	 * Unlock the resources at the given abstract paths
 	 *
-	 * @param $paths Array List of storage paths
-	 * @param $type integer LockManager::LOCK_* constant
-	 * @return string
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
+	 * @return Status
+	 * @since 1.22
 	 */
-	abstract protected function doLock( array $paths, $type );
+	final public function unlockByType( array $pathsByType ) {
+		wfProfileIn( __METHOD__ );
+		$pathsByType = $this->normalizePathsByType( $pathsByType );
+		$status = $this->doUnlockByType( $pathsByType );
+		wfProfileOut( __METHOD__ );
+		return $status;
+	}
 
 	/**
-	 * Unlock resources with the given keys and lock type
+	 * Get the base 36 SHA-1 of a string, padded to 31 digits.
+	 * Before hashing, the path will be prefixed with the domain ID.
+	 * This should be used interally for lock key or file names.
 	 *
-	 * @param $paths Array List of storage paths
-	 * @param $type integer LockManager::LOCK_* constant
+	 * @param $path string
 	 * @return string
 	 */
-	abstract protected function doUnlock( array $paths, $type );
-}
-
-/**
- * Self-releasing locks
- *
- * LockManager helper class to handle scoped locks, which
- * release when an object is destroyed or goes out of scope.
- *
- * @ingroup LockManager
- * @since 1.19
- */
-class ScopedLock {
-	/** @var LockManager */
-	protected $manager;
-	/** @var Status */
-	protected $status;
-	/** @var Array List of resource paths*/
-	protected $paths;
-
-	protected $type; // integer lock type
-
-	/**
-	 * @param $manager LockManager
-	 * @param $paths Array List of storage paths
-	 * @param $type integer LockManager::LOCK_* constant
-	 * @param $status Status
-	 */
-	protected function __construct(
-		LockManager $manager, array $paths, $type, Status $status
-	) {
-		$this->manager = $manager;
-		$this->paths = $paths;
-		$this->status = $status;
-		$this->type = $type;
+	final protected function sha1Base36Absolute( $path ) {
+		return wfBaseConvert( sha1( "{$this->domain}:{$path}" ), 16, 36, 31 );
 	}
 
 	/**
-	 * Get a ScopedLock object representing a lock on resource paths.
-	 * Any locks are released once this object goes out of scope.
-	 * The status object is updated with any errors or warnings.
+	 * Get the base 16 SHA-1 of a string, padded to 31 digits.
+	 * Before hashing, the path will be prefixed with the domain ID.
+	 * This should be used interally for lock key or file names.
 	 *
-	 * @param $manager LockManager
-	 * @param $paths Array List of storage paths
-	 * @param $type integer LockManager::LOCK_* constant
-	 * @param $status Status
-	 * @return ScopedLock|null Returns null on failure
+	 * @param $path string
+	 * @return string
 	 */
-	public static function factory(
-		LockManager $manager, array $paths, $type, Status $status
-	) {
-		$lockStatus = $manager->lock( $paths, $type );
-		$status->merge( $lockStatus );
-		if ( $lockStatus->isOK() ) {
-			return new self( $manager, $paths, $type, $status );
-		}
-		return null;
-	}
-
-	function __destruct() {
-		$wasOk = $this->status->isOK();
-		$this->status->merge( $this->manager->unlock( $this->paths, $this->type ) );
-		if ( $wasOk ) {
-			// Make sure status is OK, despite any unlockFiles() fatals
-			$this->status->setResult( true, $this->status->value );
-		}
+	final protected function sha1Base16Absolute( $path ) {
+		return sha1( "{$this->domain}:{$path}" );
 	}
-}
-
-/**
- * Version of LockManager that uses a quorum from peer servers for locks.
- * The resource space can also be sharded into separate peer groups.
- *
- * @ingroup LockManager
- * @since 1.20
- */
-abstract class QuorumLockManager extends LockManager {
-	/** @var Array Map of bucket indexes to peer server lists */
-	protected $srvsByBucket = array(); // (bucket index => (lsrv1, lsrv2, ...))
 
 	/**
-	 * @see LockManager::doLock()
-	 * @param $paths array
-	 * @param $type int
-	 * @return Status
+	 * Normalize the $paths array by converting LOCK_UW locks into the
+	 * appropriate type and removing any duplicated paths for each lock type.
+	 *
+	 * @param array $paths Map of LockManager::LOCK_* constants to lists of paths
+	 * @return Array
+	 * @since 1.22
 	 */
-	final protected function doLock( array $paths, $type ) {
-		$status = Status::newGood();
-
-		$pathsToLock = array(); // (bucket => paths)
-		// Get locks that need to be acquired (buckets => locks)...
-		foreach ( $paths as $path ) {
-			if ( isset( $this->locksHeld[$path][$type] ) ) {
-				++$this->locksHeld[$path][$type];
-			} elseif ( isset( $this->locksHeld[$path][self::LOCK_EX] ) ) {
-				$this->locksHeld[$path][$type] = 1;
-			} else {
-				$bucket = $this->getBucketFromKey( $path );
-				$pathsToLock[$bucket][] = $path;
-			}
-		}
-
-		$lockedPaths = array(); // files locked in this attempt
-		// Attempt to acquire these locks...
-		foreach ( $pathsToLock as $bucket => $paths ) {
-			// Try to acquire the locks for this bucket
-			$status->merge( $this->doLockingRequestBucket( $bucket, $paths, $type ) );
-			if ( !$status->isOK() ) {
-				$status->merge( $this->doUnlock( $lockedPaths, $type ) );
-				return $status;
-			}
-			// Record these locks as active
-			foreach ( $paths as $path ) {
-				$this->locksHeld[$path][$type] = 1; // locked
-			}
-			// Keep track of what locks were made in this attempt
-			$lockedPaths = array_merge( $lockedPaths, $paths );
+	final protected function normalizePathsByType( array $pathsByType ) {
+		$res = array();
+		foreach ( $pathsByType as $type => $paths ) {
+			$res[$this->lockTypeMap[$type]] = array_unique( $paths );
 		}
-
-		return $status;
+		return $res;
 	}
 
 	/**
-	 * @see LockManager::doUnlock()
-	 * @param $paths array
-	 * @param $type int
+	 * @see LockManager::lockByType()
+	 * @param array $paths Map of LockManager::LOCK_* constants to lists of paths
 	 * @return Status
+	 * @since 1.22
 	 */
-	final protected function doUnlock( array $paths, $type ) {
+	protected function doLockByType( array $pathsByType ) {
 		$status = Status::newGood();
-
-		$pathsToUnlock = array();
-		foreach ( $paths as $path ) {
-			if ( !isset( $this->locksHeld[$path][$type] ) ) {
-				$status->warning( 'lockmanager-notlocked', $path );
+		$lockedByType = array(); // map of (type => paths)
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doLock( $paths, $type ) );
+			if ( $status->isOK() ) {
+				$lockedByType[$type] = $paths;
 			} else {
-				--$this->locksHeld[$path][$type];
-				// Reference count the locks held and release locks when zero
-				if ( $this->locksHeld[$path][$type] <= 0 ) {
-					unset( $this->locksHeld[$path][$type] );
-					$bucket = $this->getBucketFromKey( $path );
-					$pathsToUnlock[$bucket][] = $path;
-				}
-				if ( !count( $this->locksHeld[$path] ) ) {
-					unset( $this->locksHeld[$path] ); // no SH or EX locks left for key
+				// Release the subset of locks that were acquired
+				foreach ( $lockedByType as $type => $paths ) {
+					$status->merge( $this->doUnlock( $paths, $type ) );
 				}
+				break;
 			}
 		}
-
-		// Remove these specific locks if possible, or at least release
-		// all locks once this process is currently not holding any locks.
-		foreach ( $pathsToUnlock as $bucket => $paths ) {
-			$status->merge( $this->doUnlockingRequestBucket( $bucket, $paths, $type ) );
-		}
-		if ( !count( $this->locksHeld ) ) {
-			$status->merge( $this->releaseAllLocks() );
-		}
-
 		return $status;
 	}
 
 	/**
-	 * Attempt to acquire locks with the peers for a bucket.
-	 * This is all or nothing; if any key is locked then this totally fails.
+	 * Lock resources with the given keys and lock type
 	 *
-	 * @param $bucket integer
-	 * @param $paths Array List of resource keys to lock
-	 * @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
+	 * @param array $paths List of paths
+	 * @param $type integer LockManager::LOCK_* constant
 	 * @return Status
 	 */
-	final protected function doLockingRequestBucket( $bucket, array $paths, $type ) {
-		$status = Status::newGood();
-
-		$yesVotes = 0; // locks made on trustable servers
-		$votesLeft = count( $this->srvsByBucket[$bucket] ); // remaining peers
-		$quorum = floor( $votesLeft/2 + 1 ); // simple majority
-		// Get votes for each peer, in order, until we have enough...
-		foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) {
-			if ( !$this->isServerUp( $lockSrv ) ) {
-				--$votesLeft;
-				$status->warning( 'lockmanager-fail-svr-acquire', $lockSrv );
-				continue; // server down?
-			}
-			// Attempt to acquire the lock on this peer
-			$status->merge( $this->getLocksOnServer( $lockSrv, $paths, $type ) );
-			if ( !$status->isOK() ) {
-				return $status; // vetoed; resource locked
-			}
-			++$yesVotes; // success for this peer
-			if ( $yesVotes >= $quorum ) {
-				return $status; // lock obtained
-			}
-			--$votesLeft;
-			$votesNeeded = $quorum - $yesVotes;
-			if ( $votesNeeded > $votesLeft ) {
-				break; // short-circuit
-			}
-		}
-		// At this point, we must not have met the quorum
-		$status->setResult( false );
-
-		return $status;
-	}
+	abstract protected function doLock( array $paths, $type );
 
 	/**
-	 * Attempt to release locks with the peers for a bucket
-	 *
-	 * @param $bucket integer
-	 * @param $paths Array List of resource keys to lock
-	 * @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
+	 * @see LockManager::unlockByType()
+	 * @param array $paths Map of LockManager::LOCK_* constants to lists of paths
 	 * @return Status
+	 * @since 1.22
 	 */
-	final protected function doUnlockingRequestBucket( $bucket, array $paths, $type ) {
+	protected function doUnlockByType( array $pathsByType ) {
 		$status = Status::newGood();
-
-		foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) {
-			if ( !$this->isServerUp( $lockSrv ) ) {
-				$status->fatal( 'lockmanager-fail-svr-release', $lockSrv );
-			// Attempt to release the lock on this peer
-			} else {
-				$status->merge( $this->freeLocksOnServer( $lockSrv, $paths, $type ) );
-			}
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doUnlock( $paths, $type ) );
 		}
-
 		return $status;
 	}
 
 	/**
-	 * Get the bucket for resource path.
-	 * This should avoid throwing any exceptions.
-	 *
-	 * @param $path string
-	 * @return integer
-	 */
-	protected function getBucketFromKey( $path ) {
-		$prefix = substr( sha1( $path ), 0, 2 ); // first 2 hex chars (8 bits)
-		return (int)base_convert( $prefix, 16, 10 ) % count( $this->srvsByBucket );
-	}
-
-	/**
-	 * Check if a lock server is up
-	 *
-	 * @param $lockSrv string
-	 * @return bool
-	 */
-	abstract protected function isServerUp( $lockSrv );
-
-	/**
-	 * Get a connection to a lock server and acquire locks on $paths
-	 *
-	 * @param $lockSrv string
-	 * @param $paths array
-	 * @param $type integer
-	 * @return Status
-	 */
-	abstract protected function getLocksOnServer( $lockSrv, array $paths, $type );
-
-	/**
-	 * Get a connection to a lock server and release locks on $paths.
-	 *
-	 * Subclasses must effectively implement this or releaseAllLocks().
-	 *
-	 * @param $lockSrv string
-	 * @param $paths array
-	 * @param $type integer
-	 * @return Status
-	 */
-	abstract protected function freeLocksOnServer( $lockSrv, array $paths, $type );
-
-	/**
-	 * Release all locks that this session is holding.
-	 *
-	 * Subclasses must effectively implement this or freeLocksOnServer().
+	 * Unlock resources with the given keys and lock type
 	 *
+	 * @param array $paths List of paths
+	 * @param $type integer LockManager::LOCK_* constant
 	 * @return Status
 	 */
-	abstract protected function releaseAllLocks();
+	abstract protected function doUnlock( array $paths, $type );
 }
 
 /**
@@ -403,22 +250,10 @@ abstract class QuorumLockManager extends LockManager {
  * @since 1.19
  */
 class NullLockManager extends LockManager {
-	/**
-	 * @see LockManager::doLock()
-	 * @param $paths array
-	 * @param $type int
-	 * @return Status
-	 */
 	protected function doLock( array $paths, $type ) {
 		return Status::newGood();
 	}
 
-	/**
-	 * @see LockManager::doUnlock()
-	 * @param $paths array
-	 * @param $type int
-	 * @return Status
-	 */
 	protected function doUnlock( array $paths, $type ) {
 		return Status::newGood();
 	}
diff --git a/includes/filebackend/lockmanager/LockManagerGroup.php b/includes/filebackend/lockmanager/LockManagerGroup.php
index 8c8c940a..9aff2415 100644
--- a/includes/filebackend/lockmanager/LockManagerGroup.php
+++ b/includes/filebackend/lockmanager/LockManagerGroup.php
@@ -29,33 +29,41 @@
  * @since 1.19
  */
 class LockManagerGroup {
-	/**
-	 * @var LockManagerGroup
-	 */
-	protected static $instance = null;
+	/** @var Array (domain => LockManager) */
+	protected static $instances = array();
+
+	protected $domain; // string; domain (usually wiki ID)
 
-	/** @var Array of (name => ('class' =>, 'config' =>, 'instance' =>)) */
+	/** @var Array of (name => ('class' => ..., 'config' => ..., 'instance' => ...)) */
 	protected $managers = array();
 
-	protected function __construct() {}
+	/**
+	 * @param string $domain Domain (usually wiki ID)
+	 */
+	protected function __construct( $domain ) {
+		$this->domain = $domain;
+	}
 
 	/**
+	 * @param string $domain Domain (usually wiki ID)
 	 * @return LockManagerGroup
 	 */
-	public static function singleton() {
-		if ( self::$instance == null ) {
-			self::$instance = new self();
-			self::$instance->initFromGlobals();
+	public static function singleton( $domain = false ) {
+		$domain = ( $domain === false ) ? wfWikiID() : $domain;
+		if ( !isset( self::$instances[$domain] ) ) {
+			self::$instances[$domain] = new self( $domain );
+			self::$instances[$domain]->initFromGlobals();
 		}
-		return self::$instance;
+		return self::$instances[$domain];
 	}
 
 	/**
-	 * Destroy the singleton instance, so that a new one will be created next
-	 * time singleton() is called.
+	 * Destroy the singleton instances
+	 *
+	 * @return void
 	 */
-	public static function destroySingleton() {
-		self::$instance = null;
+	public static function destroySingletons() {
+		self::$instances = array();
 	}
 
 	/**
@@ -78,6 +86,7 @@ class LockManagerGroup {
 	 */
 	protected function register( array $configs ) {
 		foreach ( $configs as $config ) {
+			$config['domain'] = $this->domain;
 			if ( !isset( $config['name'] ) ) {
 				throw new MWException( "Cannot register a lock manager with no name." );
 			}
@@ -88,8 +97,8 @@ class LockManagerGroup {
 			$class = $config['class'];
 			unset( $config['class'] ); // lock manager won't need this
 			$this->managers[$name] = array(
-				'class'    => $class,
-				'config'   => $config,
+				'class' => $class,
+				'config' => $config,
 				'instance' => null
 			);
 		}
@@ -116,6 +125,21 @@ class LockManagerGroup {
 	}
 
 	/**
+	 * Get the config array for a lock manager object with a given name
+	 *
+	 * @param $name string
+	 * @return Array
+	 * @throws MWException
+	 */
+	public function config( $name ) {
+		if ( !isset( $this->managers[$name] ) ) {
+			throw new MWException( "No lock manager defined with the name `$name`." );
+		}
+		$class = $this->managers[$name]['class'];
+		return array( 'class' => $class ) + $this->managers[$name]['config'];
+	}
+
+	/**
 	 * Get the default lock manager configured for the site.
 	 * Returns NullLockManager if no lock manager could be found.
 	 *
diff --git a/includes/filebackend/lockmanager/MemcLockManager.php b/includes/filebackend/lockmanager/MemcLockManager.php
index 57c0463d..5eab03ee 100644
--- a/includes/filebackend/lockmanager/MemcLockManager.php
+++ b/includes/filebackend/lockmanager/MemcLockManager.php
@@ -28,8 +28,8 @@
  * This is meant for multi-wiki systems that may share files.
  * All locks are non-blocking, which avoids deadlocks.
  *
- * All lock requests for a resource, identified by a hash string, will map
- * to one bucket. Each bucket maps to one or several peer servers, each running memcached.
+ * All lock requests for a resource, identified by a hash string, will map to one
+ * bucket. Each bucket maps to one or several peer servers, each running memcached.
  * A majority of peers must agree for a lock to be acquired.
  *
  * @ingroup LockManager
@@ -48,9 +48,7 @@ class MemcLockManager extends QuorumLockManager {
 	/** @var Array */
 	protected $serversUp = array(); // (server name => bool)
 
-	protected $lockExpiry; // integer; maximum time locks can be held
-	protected $session = ''; // string; random SHA-1 UUID
-	protected $wikiId = ''; // string
+	protected $session = ''; // string; random UUID
 
 	/**
 	 * Construct a new instance from configuration.
@@ -61,9 +59,9 @@ class MemcLockManager extends QuorumLockManager {
 	 *                    each having an odd-numbered list of server names (peers) as values.
 	 *   - memcConfig   : Configuration array for ObjectCache::newFromParams. [optional]
 	 *                    If set, this must use one of the memcached classes.
-	 *   - wikiId       : Wiki ID string that all resources are relative to. [optional]
 	 *
-	 * @param Array $config
+	 * @param array $config
+	 * @throws MWException
 	 */
 	public function __construct( array $config ) {
 		parent::__construct( $config );
@@ -87,19 +85,47 @@ class MemcLockManager extends QuorumLockManager {
 			}
 		}
 
-		$this->wikiId = isset( $config['wikiId'] ) ? $config['wikiId'] : wfWikiID();
+		$this->session = wfRandomString( 32 );
+	}
 
-		$met = ini_get( 'max_execution_time' ); // this is 0 in CLI mode
-		$this->lockExpiry = $met ? 2*(int)$met : 2*3600;
+	// @TODO: change this code to work in one batch
+	protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
+		$status = Status::newGood();
 
-		$this->session = wfRandomString( 32 );
+		$lockedPaths = array();
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doGetLocksOnServer( $lockSrv, $paths, $type ) );
+			if ( $status->isOK() ) {
+				$lockedPaths[$type] = isset( $lockedPaths[$type] )
+					? array_merge( $lockedPaths[$type], $paths )
+					: $paths;
+			} else {
+				foreach ( $lockedPaths as $type => $paths ) {
+					$status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) );
+				}
+				break;
+			}
+		}
+
+		return $status;
+	}
+
+	// @TODO: change this code to work in one batch
+	protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
+		$status = Status::newGood();
+
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) );
+		}
+
+		return $status;
 	}
 
 	/**
 	 * @see QuorumLockManager::getLocksOnServer()
 	 * @return Status
 	 */
-	protected function getLocksOnServer( $lockSrv, array $paths, $type ) {
+	protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
 		$status = Status::newGood();
 
 		$memc = $this->getCache( $lockSrv );
@@ -110,7 +136,7 @@ class MemcLockManager extends QuorumLockManager {
 			foreach ( $paths as $path ) {
 				$status->fatal( 'lockmanager-fail-acquirelock', $path );
 			}
-			return;
+			return $status;
 		}
 
 		// Fetch all the existing lock records...
@@ -121,8 +147,8 @@ class MemcLockManager extends QuorumLockManager {
 		foreach ( $paths as $path ) {
 			$locksKey = $this->recordKeyForPath( $path );
 			$locksHeld = isset( $lockRecords[$locksKey] )
-				? $lockRecords[$locksKey]
-				: array( self::LOCK_SH => array(), self::LOCK_EX => array() ); // init
+				? self::sanitizeLockArray( $lockRecords[$locksKey] )
+				: self::newLockArray(); // init
 			foreach ( $locksHeld[self::LOCK_EX] as $session => $expiry ) {
 				if ( $expiry < $now ) { // stale?
 					unset( $locksHeld[self::LOCK_EX][$session] );
@@ -141,7 +167,7 @@ class MemcLockManager extends QuorumLockManager {
 			}
 			if ( $status->isOK() ) {
 				// Register the session in the lock record array
-				$locksHeld[$type][$this->session] = $now + $this->lockExpiry;
+				$locksHeld[$type][$this->session] = $now + $this->lockTTL;
 				// We will update this record if none of the other locks conflict
 				$lockRecords[$locksKey] = $locksHeld;
 			}
@@ -149,9 +175,15 @@ class MemcLockManager extends QuorumLockManager {
 
 		// If there were no lock conflicts, update all the lock records...
 		if ( $status->isOK() ) {
-			foreach ( $lockRecords as $locksKey => $locksHeld ) {
-				$memc->set( $locksKey, $locksHeld );
-				wfDebug( __METHOD__ . ": acquired lock on key $locksKey.\n" );
+			foreach ( $paths as $path ) {
+				$locksKey = $this->recordKeyForPath( $path );
+				$locksHeld = $lockRecords[$locksKey];
+				$ok = $memc->set( $locksKey, $locksHeld, 7 * 86400 );
+				if ( !$ok ) {
+					$status->fatal( 'lockmanager-fail-acquirelock', $path );
+				} else {
+					wfDebug( __METHOD__ . ": acquired lock on key $locksKey.\n" );
+				}
 			}
 		}
 
@@ -165,7 +197,7 @@ class MemcLockManager extends QuorumLockManager {
 	 * @see QuorumLockManager::freeLocksOnServer()
 	 * @return Status
 	 */
-	protected function freeLocksOnServer( $lockSrv, array $paths, $type ) {
+	protected function doFreeLocksOnServer( $lockSrv, array $paths, $type ) {
 		$status = Status::newGood();
 
 		$memc = $this->getCache( $lockSrv );
@@ -186,17 +218,22 @@ class MemcLockManager extends QuorumLockManager {
 		foreach ( $paths as $path ) {
 			$locksKey = $this->recordKeyForPath( $path ); // lock record
 			if ( !isset( $lockRecords[$locksKey] ) ) {
+				$status->warning( 'lockmanager-fail-releaselock', $path );
 				continue; // nothing to do
 			}
-			$locksHeld = $lockRecords[$locksKey];
-			if ( is_array( $locksHeld ) && isset( $locksHeld[$type] ) ) {
-				unset( $locksHeld[$type][$this->session] );
-				$ok = $memc->set( $locksKey, $locksHeld );
+			$locksHeld = self::sanitizeLockArray( $lockRecords[$locksKey] );
+			if ( isset( $locksHeld[$type][$this->session] ) ) {
+				unset( $locksHeld[$type][$this->session] ); // unregister this session
+				if ( $locksHeld === self::newLockArray() ) {
+					$ok = $memc->delete( $locksKey );
+				} else {
+					$ok = $memc->set( $locksKey, $locksHeld );
+				}
+				if ( !$ok ) {
+					$status->fatal( 'lockmanager-fail-releaselock', $path );
+				}
 			} else {
-				$ok = true;
-			}
-			if ( !$ok ) {
-				$status->fatal( 'lockmanager-fail-releaselock', $path );
+				$status->warning( 'lockmanager-fail-releaselock', $path );
 			}
 			wfDebug( __METHOD__ . ": released lock on key $locksKey.\n" );
 		}
@@ -226,7 +263,7 @@ class MemcLockManager extends QuorumLockManager {
 	/**
 	 * Get the MemcachedBagOStuff object for a $lockSrv
 	 *
-	 * @param $lockSrv string Server name
+	 * @param string $lockSrv Server name
 	 * @return MemcachedBagOStuff|null
 	 */
 	protected function getCache( $lockSrv ) {
@@ -234,7 +271,7 @@ class MemcLockManager extends QuorumLockManager {
 		if ( isset( $this->bagOStuffs[$lockSrv] ) ) {
 			$memc = $this->bagOStuffs[$lockSrv];
 			if ( !isset( $this->serversUp[$lockSrv] ) ) {
-				$this->serversUp[$lockSrv] = $memc->set( 'MemcLockManager:ping', 1, 1 );
+				$this->serversUp[$lockSrv] = $memc->set( __CLASS__ . ':ping', 1, 1 );
 				if ( !$this->serversUp[$lockSrv] ) {
 					trigger_error( __METHOD__ . ": Could not contact $lockSrv.", E_USER_WARNING );
 				}
@@ -251,14 +288,32 @@ class MemcLockManager extends QuorumLockManager {
 	 * @return string
 	 */
 	protected function recordKeyForPath( $path ) {
-		$hash = LockManager::sha1Base36( $path );
-		list( $db, $prefix ) = wfSplitWikiID( $this->wikiId );
-		return wfForeignMemcKey( $db, $prefix, __CLASS__, 'locks', $hash );
+		return implode( ':', array( __CLASS__, 'locks', $this->sha1Base36Absolute( $path ) ) );
+	}
+
+	/**
+	 * @return Array An empty lock structure for a key
+	 */
+	protected static function newLockArray() {
+		return array( self::LOCK_SH => array(), self::LOCK_EX => array() );
+	}
+
+	/**
+	 * @param $a array
+	 * @return Array An empty lock structure for a key
+	 */
+	protected static function sanitizeLockArray( $a ) {
+		if ( is_array( $a ) && isset( $a[self::LOCK_EX] ) && isset( $a[self::LOCK_SH] ) ) {
+			return $a;
+		} else {
+			trigger_error( __METHOD__ . ": reset invalid lock array.", E_USER_WARNING );
+			return self::newLockArray();
+		}
 	}
 
 	/**
 	 * @param $memc MemcachedBagOStuff
-	 * @param $keys Array List of keys to acquire
+	 * @param array $keys List of keys to acquire
 	 * @return bool
 	 */
 	protected function acquireMutexes( MemcachedBagOStuff $memc, array $keys ) {
@@ -275,7 +330,7 @@ class MemcLockManager extends QuorumLockManager {
 		$start = microtime( true );
 		do {
 			if ( ( ++$rounds % 4 ) == 0 ) {
-				usleep( 1000*50 ); // 50 ms
+				usleep( 1000 * 50 ); // 50 ms
 			}
 			foreach ( array_diff( $keys, $lockedKeys ) as $key ) {
 				if ( $memc->add( "$key:mutex", 1, 180 ) ) { // lock record
@@ -284,10 +339,10 @@ class MemcLockManager extends QuorumLockManager {
 					continue; // acquire in order
 				}
 			}
-		} while ( count( $lockedKeys ) < count( $keys ) && ( microtime( true ) - $start ) <= 6 );
+		} while ( count( $lockedKeys ) < count( $keys ) && ( microtime( true ) - $start ) <= 3 );
 
 		if ( count( $lockedKeys ) != count( $keys ) ) {
-			$this->releaseMutexes( $lockedKeys ); // failed; release what was locked
+			$this->releaseMutexes( $memc, $lockedKeys ); // failed; release what was locked
 			return false;
 		}
 
@@ -296,7 +351,7 @@ class MemcLockManager extends QuorumLockManager {
 
 	/**
 	 * @param $memc MemcachedBagOStuff
-	 * @param $keys Array List of acquired keys
+	 * @param array $keys List of acquired keys
 	 * @return void
 	 */
 	protected function releaseMutexes( MemcachedBagOStuff $memc, array $keys ) {
diff --git a/includes/filebackend/lockmanager/QuorumLockManager.php b/includes/filebackend/lockmanager/QuorumLockManager.php
new file mode 100644
index 00000000..8356d32a
--- /dev/null
+++ b/includes/filebackend/lockmanager/QuorumLockManager.php
@@ -0,0 +1,246 @@
+<?php
+/**
+ * Version of LockManager that uses a quorum from peer servers for locks.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup LockManager
+ */
+
+/**
+ * Version of LockManager that uses a quorum from peer servers for locks.
+ * The resource space can also be sharded into separate peer groups.
+ *
+ * @ingroup LockManager
+ * @since 1.20
+ */
+abstract class QuorumLockManager extends LockManager {
+	/** @var Array Map of bucket indexes to peer server lists */
+	protected $srvsByBucket = array(); // (bucket index => (lsrv1, lsrv2, ...))
+	/** @var Array Map of degraded buckets */
+	protected $degradedBuckets = array(); // (buckey index => UNIX timestamp)
+
+	final protected function doLock( array $paths, $type ) {
+		return $this->doLockByType( array( $type => $paths ) );
+	}
+
+	final protected function doUnlock( array $paths, $type ) {
+		return $this->doUnlockByType( array( $type => $paths ) );
+	}
+
+	protected function doLockByType( array $pathsByType ) {
+		$status = Status::newGood();
+
+		$pathsToLock = array(); // (bucket => type => paths)
+		// Get locks that need to be acquired (buckets => locks)...
+		foreach ( $pathsByType as $type => $paths ) {
+			foreach ( $paths as $path ) {
+				if ( isset( $this->locksHeld[$path][$type] ) ) {
+					++$this->locksHeld[$path][$type];
+				} else {
+					$bucket = $this->getBucketFromPath( $path );
+					$pathsToLock[$bucket][$type][] = $path;
+				}
+			}
+		}
+
+		$lockedPaths = array(); // files locked in this attempt (type => paths)
+		// Attempt to acquire these locks...
+		foreach ( $pathsToLock as $bucket => $pathsToLockByType ) {
+			// Try to acquire the locks for this bucket
+			$status->merge( $this->doLockingRequestBucket( $bucket, $pathsToLockByType ) );
+			if ( !$status->isOK() ) {
+				$status->merge( $this->doUnlockByType( $lockedPaths ) );
+				return $status;
+			}
+			// Record these locks as active
+			foreach ( $pathsToLockByType as $type => $paths ) {
+				foreach ( $paths as $path ) {
+					$this->locksHeld[$path][$type] = 1; // locked
+					// Keep track of what locks were made in this attempt
+					$lockedPaths[$type][] = $path;
+				}
+			}
+		}
+
+		return $status;
+	}
+
+	protected function doUnlockByType( array $pathsByType ) {
+		$status = Status::newGood();
+
+		$pathsToUnlock = array(); // (bucket => type => paths)
+		foreach ( $pathsByType as $type => $paths ) {
+			foreach ( $paths as $path ) {
+				if ( !isset( $this->locksHeld[$path][$type] ) ) {
+					$status->warning( 'lockmanager-notlocked', $path );
+				} else {
+					--$this->locksHeld[$path][$type];
+					// Reference count the locks held and release locks when zero
+					if ( $this->locksHeld[$path][$type] <= 0 ) {
+						unset( $this->locksHeld[$path][$type] );
+						$bucket = $this->getBucketFromPath( $path );
+						$pathsToUnlock[$bucket][$type][] = $path;
+					}
+					if ( !count( $this->locksHeld[$path] ) ) {
+						unset( $this->locksHeld[$path] ); // no SH or EX locks left for key
+					}
+				}
+			}
+		}
+
+		// Remove these specific locks if possible, or at least release
+		// all locks once this process is currently not holding any locks.
+		foreach ( $pathsToUnlock as $bucket => $pathsToUnlockByType ) {
+			$status->merge( $this->doUnlockingRequestBucket( $bucket, $pathsToUnlockByType ) );
+		}
+		if ( !count( $this->locksHeld ) ) {
+			$status->merge( $this->releaseAllLocks() );
+			$this->degradedBuckets = array(); // safe to retry the normal quorum
+		}
+
+		return $status;
+	}
+
+	/**
+	 * Attempt to acquire locks with the peers for a bucket.
+	 * This is all or nothing; if any key is locked then this totally fails.
+	 *
+	 * @param $bucket integer
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
+	 * @return Status
+	 */
+	final protected function doLockingRequestBucket( $bucket, array $pathsByType ) {
+		$status = Status::newGood();
+
+		$yesVotes = 0; // locks made on trustable servers
+		$votesLeft = count( $this->srvsByBucket[$bucket] ); // remaining peers
+		$quorum = floor( $votesLeft / 2 + 1 ); // simple majority
+		// Get votes for each peer, in order, until we have enough...
+		foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) {
+			if ( !$this->isServerUp( $lockSrv ) ) {
+				--$votesLeft;
+				$status->warning( 'lockmanager-fail-svr-acquire', $lockSrv );
+				$this->degradedBuckets[$bucket] = time();
+				continue; // server down?
+			}
+			// Attempt to acquire the lock on this peer
+			$status->merge( $this->getLocksOnServer( $lockSrv, $pathsByType ) );
+			if ( !$status->isOK() ) {
+				return $status; // vetoed; resource locked
+			}
+			++$yesVotes; // success for this peer
+			if ( $yesVotes >= $quorum ) {
+				return $status; // lock obtained
+			}
+			--$votesLeft;
+			$votesNeeded = $quorum - $yesVotes;
+			if ( $votesNeeded > $votesLeft ) {
+				break; // short-circuit
+			}
+		}
+		// At this point, we must not have met the quorum
+		$status->setResult( false );
+
+		return $status;
+	}
+
+	/**
+	 * Attempt to release locks with the peers for a bucket
+	 *
+	 * @param $bucket integer
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
+	 * @return Status
+	 */
+	final protected function doUnlockingRequestBucket( $bucket, array $pathsByType ) {
+		$status = Status::newGood();
+
+		$yesVotes = 0; // locks freed on trustable servers
+		$votesLeft = count( $this->srvsByBucket[$bucket] ); // remaining peers
+		$quorum = floor( $votesLeft / 2 + 1 ); // simple majority
+		$isDegraded = isset( $this->degradedBuckets[$bucket] ); // not the normal quorum?
+		foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) {
+			if ( !$this->isServerUp( $lockSrv ) ) {
+				$status->warning( 'lockmanager-fail-svr-release', $lockSrv );
+			// Attempt to release the lock on this peer
+			} else {
+				$status->merge( $this->freeLocksOnServer( $lockSrv, $pathsByType ) );
+				++$yesVotes; // success for this peer
+				// Normally the first peers form the quorum, and the others are ignored.
+				// Ignore them in this case, but not when an alternative quorum was used.
+				if ( $yesVotes >= $quorum && !$isDegraded ) {
+					break; // lock released
+				}
+			}
+		}
+		// Set a bad status if the quorum was not met.
+		// Assumes the same "up" servers as during the acquire step.
+		$status->setResult( $yesVotes >= $quorum );
+
+		return $status;
+	}
+
+	/**
+	 * Get the bucket for resource path.
+	 * This should avoid throwing any exceptions.
+	 *
+	 * @param $path string
+	 * @return integer
+	 */
+	protected function getBucketFromPath( $path ) {
+		$prefix = substr( sha1( $path ), 0, 2 ); // first 2 hex chars (8 bits)
+		return (int)base_convert( $prefix, 16, 10 ) % count( $this->srvsByBucket );
+	}
+
+	/**
+	 * Check if a lock server is up.
+	 * This should process cache results to reduce RTT.
+	 *
+	 * @param $lockSrv string
+	 * @return bool
+	 */
+	abstract protected function isServerUp( $lockSrv );
+
+	/**
+	 * Get a connection to a lock server and acquire locks
+	 *
+	 * @param $lockSrv string
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
+	 * @return Status
+	 */
+	abstract protected function getLocksOnServer( $lockSrv, array $pathsByType );
+
+	/**
+	 * Get a connection to a lock server and release locks on $paths.
+	 *
+	 * Subclasses must effectively implement this or releaseAllLocks().
+	 *
+	 * @param $lockSrv string
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
+	 * @return Status
+	 */
+	abstract protected function freeLocksOnServer( $lockSrv, array $pathsByType );
+
+	/**
+	 * Release all locks that this session is holding.
+	 *
+	 * Subclasses must effectively implement this or freeLocksOnServer().
+	 *
+	 * @return Status
+	 */
+	abstract protected function releaseAllLocks();
+}
diff --git a/includes/filebackend/lockmanager/RedisLockManager.php b/includes/filebackend/lockmanager/RedisLockManager.php
new file mode 100644
index 00000000..43b0198a
--- /dev/null
+++ b/includes/filebackend/lockmanager/RedisLockManager.php
@@ -0,0 +1,288 @@
+<?php
+/**
+ * Version of LockManager based on using redis servers.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup LockManager
+ */
+
+/**
+ * Manage locks using redis servers.
+ *
+ * Version of LockManager based on using redis servers.
+ * This is meant for multi-wiki systems that may share files.
+ * All locks are non-blocking, which avoids deadlocks.
+ *
+ * All lock requests for a resource, identified by a hash string, will map to one
+ * bucket. Each bucket maps to one or several peer servers, each running redis.
+ * A majority of peers must agree for a lock to be acquired.
+ *
+ * This class requires Redis 2.6 as it makes use Lua scripts for fast atomic operations.
+ *
+ * @ingroup LockManager
+ * @since 1.22
+ */
+class RedisLockManager extends QuorumLockManager {
+	/** @var Array Mapping of lock types to the type actually used */
+	protected $lockTypeMap = array(
+		self::LOCK_SH => self::LOCK_SH,
+		self::LOCK_UW => self::LOCK_SH,
+		self::LOCK_EX => self::LOCK_EX
+	);
+
+	/** @var RedisConnectionPool */
+	protected $redisPool;
+	/** @var Array Map server names to hostname/IP and port numbers */
+	protected $lockServers = array();
+
+	protected $session = ''; // string; random UUID
+
+	/**
+	 * Construct a new instance from configuration.
+	 *
+	 * $config paramaters include:
+	 *   - lockServers  : Associative array of server names to "<IP>:<port>" strings.
+	 *   - srvsByBucket : Array of 1-16 consecutive integer keys, starting from 0,
+	 *                    each having an odd-numbered list of server names (peers) as values.
+	 *   - redisConfig  : Configuration for RedisConnectionPool::__construct().
+	 *
+	 * @param Array $config
+	 * @throws MWException
+	 */
+	public function __construct( array $config ) {
+		parent::__construct( $config );
+
+		$this->lockServers = $config['lockServers'];
+		// Sanitize srvsByBucket config to prevent PHP errors
+		$this->srvsByBucket = array_filter( $config['srvsByBucket'], 'is_array' );
+		$this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive
+
+		$config['redisConfig']['serializer'] = 'none';
+		$this->redisPool = RedisConnectionPool::singleton( $config['redisConfig'] );
+
+		$this->session = wfRandomString( 32 );
+	}
+
+	// @TODO: change this code to work in one batch
+	protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
+		$status = Status::newGood();
+
+		$lockedPaths = array();
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doGetLocksOnServer( $lockSrv, $paths, $type ) );
+			if ( $status->isOK() ) {
+				$lockedPaths[$type] = isset( $lockedPaths[$type] )
+					? array_merge( $lockedPaths[$type], $paths )
+					: $paths;
+			} else {
+				foreach ( $lockedPaths as $type => $paths ) {
+					$status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) );
+				}
+				break;
+			}
+		}
+
+		return $status;
+	}
+
+	// @TODO: change this code to work in one batch
+	protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
+		$status = Status::newGood();
+
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doFreeLocksOnServer( $lockSrv, $paths, $type ) );
+		}
+
+		return $status;
+	}
+
+	protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
+		$status = Status::newGood();
+
+		$server = $this->lockServers[$lockSrv];
+		$conn = $this->redisPool->getConnection( $server );
+		if ( !$conn ) {
+			foreach ( $paths as $path ) {
+				$status->fatal( 'lockmanager-fail-acquirelock', $path );
+			}
+			return $status;
+		}
+
+		$keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
+
+		try {
+			static $script =
+<<<LUA
+			if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
+				return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
+			end
+			local failed = {}
+			-- Check that all the locks can be acquired
+			for i,resourceKey in ipairs(KEYS) do
+				local keyIsFree = true
+				local currentLocks = redis.call('hKeys',resourceKey)
+				for i,lockKey in ipairs(currentLocks) do
+					local _, _, type, session = string.find(lockKey,"(%w+):(%w+)")
+					-- Check any locks that are not owned by this session
+					if session ~= ARGV[2] then
+						local lockTimestamp = redis.call('hGet',resourceKey,lockKey)
+						if 1*lockTimestamp < ( ARGV[4] - ARGV[3] ) then
+							-- Lock is stale, so just prune it out
+							redis.call('hDel',resourceKey,lockKey)
+						elseif ARGV[1] == 'EX' or type == 'EX' then
+							keyIsFree = false
+							break
+						end
+					end
+				end
+				if not keyIsFree then
+					failed[#failed+1] = resourceKey
+				end
+			end
+			-- If all locks could be acquired, then do so
+			if #failed == 0 then
+				for i,resourceKey in ipairs(KEYS) do
+					redis.call('hSet',resourceKey,ARGV[1] .. ':' .. ARGV[2],ARGV[4])
+					-- In addition to invalidation logic, be sure to garbage collect
+					redis.call('expire',resourceKey,ARGV[3])
+				end
+			end
+			return failed
+LUA;
+			$res = $conn->luaEval( $script,
+				array_merge(
+					$keys, // KEYS[0], KEYS[1],...KEYS[N]
+					array(
+						$type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
+						$this->session, // ARGV[2]
+						$this->lockTTL, // ARGV[3]
+						time() // ARGV[4]
+					)
+				),
+				count( $keys ) # number of first argument(s) that are keys
+			);
+		} catch ( RedisException $e ) {
+			$res = false;
+			$this->redisPool->handleException( $server, $conn, $e );
+		}
+
+		if ( $res === false ) {
+			foreach ( $paths as $path ) {
+				$status->fatal( 'lockmanager-fail-acquirelock', $path );
+			}
+		} else {
+			$pathsByKey = array_combine( $keys, $paths );
+			foreach ( $res as $key ) {
+				$status->fatal( 'lockmanager-fail-acquirelock', $pathsByKey[$key] );
+			}
+		}
+
+		return $status;
+	}
+
+	protected function doFreeLocksOnServer( $lockSrv, array $paths, $type ) {
+		$status = Status::newGood();
+
+		$server = $this->lockServers[$lockSrv];
+		$conn = $this->redisPool->getConnection( $server );
+		if ( !$conn ) {
+			foreach ( $paths as $path ) {
+				$status->fatal( 'lockmanager-fail-releaselock', $path );
+			}
+			return $status;
+		}
+
+		$keys = array_map( array( $this, 'recordKeyForPath' ), $paths ); // lock records
+
+		try {
+			static $script =
+<<<LUA
+			if ARGV[1] ~= 'EX' and ARGV[1] ~= 'SH' then
+				return redis.error_reply('Unrecognized lock type given (must be EX or SH)')
+			end
+			local failed = {}
+			for i,resourceKey in ipairs(KEYS) do
+				local released = redis.call('hDel',resourceKey,ARGV[1] .. ':' .. ARGV[2])
+				if released > 0 then
+					-- Remove the whole structure if it is now empty
+					if redis.call('hLen',resourceKey) == 0 then
+						redis.call('del',resourceKey)
+					end
+				else
+					failed[#failed+1] = resourceKey
+				end
+			end
+			return failed
+LUA;
+			$res = $conn->luaEval( $script,
+				array_merge(
+					$keys, // KEYS[0], KEYS[1],...KEYS[N]
+					array(
+						$type === self::LOCK_SH ? 'SH' : 'EX', // ARGV[1]
+						$this->session // ARGV[2]
+					)
+				),
+				count( $keys ) # number of first argument(s) that are keys
+			);
+		} catch ( RedisException $e ) {
+			$res = false;
+			$this->redisPool->handleException( $server, $conn, $e );
+		}
+
+		if ( $res === false ) {
+			foreach ( $paths as $path ) {
+				$status->fatal( 'lockmanager-fail-releaselock', $path );
+			}
+		} else {
+			$pathsByKey = array_combine( $keys, $paths );
+			foreach ( $res as $key ) {
+				$status->fatal( 'lockmanager-fail-releaselock', $pathsByKey[$key] );
+			}
+		}
+
+		return $status;
+	}
+
+	protected function releaseAllLocks() {
+		return Status::newGood(); // not supported
+	}
+
+	protected function isServerUp( $lockSrv ) {
+		return (bool)$this->redisPool->getConnection( $this->lockServers[$lockSrv] );
+	}
+
+	/**
+	 * @param $path string
+	 * @return string
+	 */
+	protected function recordKeyForPath( $path ) {
+		return implode( ':', array( __CLASS__, 'locks', $this->sha1Base36Absolute( $path ) ) );
+	}
+
+	/**
+	 * Make sure remaining locks get cleared for sanity
+	 */
+	function __destruct() {
+		while ( count( $this->locksHeld ) ) {
+			foreach ( $this->locksHeld as $path => $locks ) {
+				$this->doUnlock( array( $path ), self::LOCK_EX );
+				$this->doUnlock( array( $path ), self::LOCK_SH );
+			}
+		}
+	}
+}
diff --git a/includes/filebackend/lockmanager/ScopedLock.php b/includes/filebackend/lockmanager/ScopedLock.php
new file mode 100644
index 00000000..5faad4a6
--- /dev/null
+++ b/includes/filebackend/lockmanager/ScopedLock.php
@@ -0,0 +1,104 @@
+<?php
+/**
+ * Resource locking handling.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup LockManager
+ * @author Aaron Schulz
+ */
+
+/**
+ * Self-releasing locks
+ *
+ * LockManager helper class to handle scoped locks, which
+ * release when an object is destroyed or goes out of scope.
+ *
+ * @ingroup LockManager
+ * @since 1.19
+ */
+class ScopedLock {
+	/** @var LockManager */
+	protected $manager;
+	/** @var Status */
+	protected $status;
+	/** @var Array Map of lock types to resource paths */
+	protected $pathsByType;
+
+	/**
+	 * @param LockManager $manager
+	 * @param array $pathsByType Map of lock types to path lists
+	 * @param Status $status
+	 */
+	protected function __construct( LockManager $manager, array $pathsByType, Status $status ) {
+		$this->manager = $manager;
+		$this->pathsByType = $pathsByType;
+		$this->status = $status;
+	}
+
+	/**
+	 * Get a ScopedLock object representing a lock on resource paths.
+	 * Any locks are released once this object goes out of scope.
+	 * The status object is updated with any errors or warnings.
+	 *
+	 * $type can be "mixed" and $paths can be a map of types to paths (since 1.22).
+	 * Otherwise $type should be an integer and $paths should be a list of paths.
+	 *
+	 * @param LockManager $manager
+	 * @param array $paths List of storage paths or map of lock types to path lists
+	 * @param integer|string $type LockManager::LOCK_* constant or "mixed"
+	 * @param Status $status
+	 * @param integer $timeout Timeout in seconds (0 means non-blocking) (since 1.22)
+	 * @return ScopedLock|null Returns null on failure
+	 */
+	public static function factory(
+		LockManager $manager, array $paths, $type, Status $status, $timeout = 0
+	) {
+		$pathsByType = is_integer( $type ) ? array( $type => $paths ) : $paths;
+		$lockStatus = $manager->lockByType( $pathsByType, $timeout );
+		$status->merge( $lockStatus );
+		if ( $lockStatus->isOK() ) {
+			return new self( $manager, $pathsByType, $status );
+		}
+		return null;
+	}
+
+	/**
+	 * Release a scoped lock and set any errors in the attatched Status object.
+	 * This is useful for early release of locks before function scope is destroyed.
+	 * This is the same as setting the lock object to null.
+	 *
+	 * @param ScopedLock $lock
+	 * @return void
+	 * @since 1.21
+	 */
+	public static function release( ScopedLock &$lock = null ) {
+		$lock = null;
+	}
+
+	/**
+	 * Release the locks when this goes out of scope
+	 */
+	function __destruct() {
+		$wasOk = $this->status->isOK();
+		$this->status->merge( $this->manager->unlockByType( $this->pathsByType ) );
+		if ( $wasOk ) {
+			// Make sure status is OK, despite any unlockFiles() fatals
+			$this->status->setResult( true, $this->status->value );
+		}
+	}
+}