Update to MediaWiki 1.22.0

19 files changed, 1106 insertions, 1124 deletions

diff --git a/includes/filebackend/FSFile.php b/includes/filebackend/FSFile.php
index 7d0dbd52..8f0a1334 100644
--- a/includes/filebackend/FSFile.php
+++ b/includes/filebackend/FSFile.php
@@ -28,7 +28,7 @@
  */
 class FSFile {
 	protected $path; // path to file
-	private $sha1Base36 = null; // File Sha1Base36
+	protected $sha1Base36; // file SHA-1 in base 36
 
 	/**
 	 * Sets up the file object
@@ -98,7 +98,7 @@ 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
@@ -171,7 +171,7 @@ class FSFile {
 	/**
 	 * Exract image size information
 	 *
-	 * @param $gis array
+	 * @param array $gis
 	 * @return Array
 	 */
 	protected function extractImageSizeInfo( array $gis ) {
@@ -194,7 +194,7 @@ class FSFile {
 	 * 160 log 2 / log 36 = 30.95, so the 160-bit hash fills 31 digits in base 36
 	 * fairly neatly.
 	 *
-	 * @param $recache bool
+	 * @param bool $recache
 	 * @return bool|string False on failure
 	 */
 	public function getSha1Base36( $recache = false ) {
@@ -220,7 +220,7 @@ class FSFile {
 	/**
 	 * Get the final file extension from a file system path
 	 *
-	 * @param $path string
+	 * @param string $path
 	 * @return string
 	 */
 	public static function extensionFromPath( $path ) {
@@ -232,9 +232,8 @@ class FSFile {
 	 * Get an associative array containing information about a file in the local filesystem.
 	 *
 	 * @param string $path absolute local filesystem 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 static function getPropsFromPath( $path, $ext = true ) {
@@ -249,19 +248,11 @@ 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 $recache bool
-	 *
+	 * @param string $path
 	 * @return bool|string False on failure
 	 */
-	public static function getSha1Base36FromPath( $path, $recache = false ) {
-		static $sha1Base36 = array();
-
-		if ( !isset( $sha1Base36[$path] ) || $recache ) {
-			$fsFile = new self( $path );
-			$sha1Base36[$path] = $fsFile->getSha1Base36();
-		}
-
-		return $sha1Base36[$path];
+	public static function getSha1Base36FromPath( $path ) {
+		$fsFile = new self( $path );
+		return $fsFile->getSha1Base36();
 	}
 }
diff --git a/includes/filebackend/FSFileBackend.php b/includes/filebackend/FSFileBackend.php
index c9769989..6d642162 100644
--- a/includes/filebackend/FSFileBackend.php
+++ b/includes/filebackend/FSFileBackend.php
@@ -82,12 +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 ) ) {
@@ -121,8 +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 ) {
@@ -153,10 +147,6 @@ class FSFileBackend extends FileBackendStore {
 		return $fsPath;
 	}
 
-	/**
-	 * @see FileBackendStore::isPathUsableInternal()
-	 * @return bool
-	 */
 	public function isPathUsableInternal( $storagePath ) {
 		$fsPath = $this->resolveToFSPath( $storagePath );
 		if ( $fsPath === null ) {
@@ -178,10 +168,6 @@ class FSFileBackend extends FileBackendStore {
 		return $ok;
 	}
 
-	/**
-	 * @see FileBackendStore::doCreateInternal()
-	 * @return Status
-	 */
 	protected function doCreateInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -235,10 +221,6 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doStoreInternal()
-	 * @return Status
-	 */
 	protected function doStoreInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -284,10 +266,6 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doCopyInternal()
-	 * @return Status
-	 */
 	protected function doCopyInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -319,7 +297,7 @@ class FSFileBackend extends FileBackendStore {
 			$status->value = new FSFileOpHandle( $this, $params, 'Copy', $cmd, $dest );
 		} else { // immediate write
 			$this->trapWarnings();
-			$ok = copy( $source, $dest );
+			$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 ) ) ) {
@@ -348,10 +326,6 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doMoveInternal()
-	 * @return Status
-	 */
 	protected function doMoveInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -383,7 +357,7 @@ class FSFileBackend extends FileBackendStore {
 			$status->value = new FSFileOpHandle( $this, $params, 'Move', $cmd );
 		} else { // immediate write
 			$this->trapWarnings();
-			$ok = rename( $source, $dest );
+			$ok = ( $source === $dest ) ? true : rename( $source, $dest );
 			$this->untrapWarnings();
 			clearstatcache(); // file no longer at source
 			if ( !$ok ) {
@@ -405,10 +379,6 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doDeleteInternal()
-	 * @return Status
-	 */
 	protected function doDeleteInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -454,10 +424,6 @@ class FSFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doPrepareInternal()
-	 * @return Status
-	 */
 	protected function doPrepareInternal( $fullCont, $dirRel, array $params ) {
 		$status = Status::newGood();
 		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
@@ -481,10 +447,6 @@ class FSFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doSecureInternal()
-	 * @return Status
-	 */
 	protected function doSecureInternal( $fullCont, $dirRel, array $params ) {
 		$status = Status::newGood();
 		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
@@ -512,10 +474,6 @@ class FSFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doPublishInternal()
-	 * @return Status
-	 */
 	protected function doPublishInternal( $fullCont, $dirRel, array $params ) {
 		$status = Status::newGood();
 		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
@@ -543,10 +501,6 @@ class FSFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doCleanInternal()
-	 * @return Status
-	 */
 	protected function doCleanInternal( $fullCont, $dirRel, array $params ) {
 		$status = Status::newGood();
 		list( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
@@ -560,10 +514,6 @@ class FSFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doFileExists()
-	 * @return array|bool|null
-	 */
 	protected function doGetFileStat( array $params ) {
 		$source = $this->resolveToFSPath( $params['src'] );
 		if ( $source === null ) {
@@ -577,7 +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
@@ -593,10 +543,6 @@ 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( , $shortCont, ) = FileBackend::splitStoragePath( $params['dir'] );
 		$contRoot = $this->containerFSRoot( $shortCont, $fullCont ); // must be valid
@@ -647,10 +593,6 @@ class FSFileBackend extends FileBackendStore {
 		return new FSFileBackendFileList( $dir, $params );
 	}
 
-	/**
-	 * @see FileBackendStore::doGetLocalReferenceMulti()
-	 * @return Array
-	 */
 	protected function doGetLocalReferenceMulti( array $params ) {
 		$fsFiles = array(); // (path => FSFile)
 
@@ -666,10 +608,6 @@ class FSFileBackend extends FileBackendStore {
 		return $fsFiles;
 	}
 
-	/**
-	 * @see FileBackendStore::doGetLocalCopyMulti()
-	 * @return Array
-	 */
 	protected function doGetLocalCopyMulti( array $params ) {
 		$tmpFiles = array(); // (path => TempFSFile)
 
@@ -702,18 +640,10 @@ class FSFileBackend extends FileBackendStore {
 		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();
 
@@ -807,11 +737,12 @@ class FSFileBackend extends FileBackendStore {
 	}
 
 	/**
-	 * @param $errno integer
-	 * @param $errstr string
+	 * @param integer $errno
+	 * @param string $errstr
 	 * @return bool
+	 * @access private
 	 */
-	private function handleWarning( $errno, $errstr ) {
+	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
@@ -826,13 +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;
@@ -858,11 +791,11 @@ abstract class FSFileBackendList implements Iterator {
 
 	/**
 	 * @param string $dir file system directory
-	 * @param $params array
+	 * @param array $params
 	 */
 	public function __construct( $dir, array $params ) {
 		$path = realpath( $dir ); // normalize
-		if( $path === false ) {
+		if ( $path === false ) {
 			$path = $dir;
 		}
 		$this->suffixStart = strlen( $path ) + 1; // size of "path/to/dir/"
@@ -921,8 +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;
 	}
@@ -936,8 +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." );
 		}
 	}
 
@@ -958,12 +891,12 @@ 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( $dir ) {
 		$path = realpath( $dir );
-		if( $path === false ) {
+		if ( $path === false ) {
 			$path = $dir;
 		}
 		return strtr( substr( $path, $this->suffixStart ), '\\', '/' );
diff --git a/includes/filebackend/FileBackend.php b/includes/filebackend/FileBackend.php
index f40b8c16..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.
@@ -95,7 +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 ) {
@@ -191,7 +190,6 @@ 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
@@ -204,7 +202,6 @@ 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
@@ -218,7 +215,7 @@ abstract class FileBackend {
 	 *         'overwrite'           => <boolean>,
 	 *         'overwriteSame'       => <boolean>,
 	 *         'ignoreMissingSource' => <boolean>, # since 1.21
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
 	 *
@@ -231,7 +228,7 @@ abstract class FileBackend {
 	 *         'overwrite'           => <boolean>,
 	 *         'overwriteSame'       => <boolean>,
 	 *         'ignoreMissingSource' => <boolean>, # since 1.21
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
 	 *
@@ -249,7 +246,6 @@ abstract class FileBackend {
 	 *     array(
 	 *         'op'                  => 'describe',
 	 *         'src'                 => <storage path>,
-	 *         'disposition'         => <Content-Disposition header value>,
 	 *         'headers'             => <HTTP header name/value map>
 	 *     )
 	 * @endcode
@@ -265,19 +261,19 @@ 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         : If supplied, the backend will return a Content-Disposition
-	 *                           header when GETs/HEADs of the destination file are made.
-	 *                           Backends that don't support metadata ignore this.
-	 *                           See http://tools.ietf.org/html/rfc6266. (since 1.20)
-	 *   - headers             : If supplied, the backend will return these headers when
-	 *                           GETs/HEADs of the destination file are made. Header values
-	 *                           should be smaller than 256 bytes, often options or numbers.
-	 *                           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.
+	 *   - 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:
@@ -318,9 +314,17 @@ 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
+		}
 		if ( empty( $opts['force'] ) ) { // sanity
 			unset( $opts['nonLocking'] );
 		}
+		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 );
 	}
@@ -452,7 +456,6 @@ 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
@@ -463,7 +466,6 @@ abstract class FileBackend {
 	 *         'op'                  => 'store',
 	 *         'src'                 => <file system path>,
 	 *         'dst'                 => <storage path>,
-	 *         'disposition'         => <Content-Disposition header value>,
 	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
@@ -475,7 +477,7 @@ abstract class FileBackend {
 	 *         'src'                 => <storage path>,
 	 *         'dst'                 => <storage path>,
 	 *         'ignoreMissingSource' => <boolean>, # since 1.21
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
 	 *
@@ -486,7 +488,7 @@ abstract class FileBackend {
 	 *         'src'                 => <storage path>,
 	 *         'dst'                 => <storage path>,
 	 *         'ignoreMissingSource' => <boolean>, # since 1.21
-	 *         'disposition'         => <Content-Disposition header value>
+	 *         'headers'             => <HTTP header name/value map> # since 1.21
 	 *     )
 	 * @endcode
 	 *
@@ -504,7 +506,6 @@ abstract class FileBackend {
 	 *     array(
 	 *         'op'                  => 'describe',
 	 *         'src'                 => <storage path>,
-	 *         'disposition'         => <Content-Disposition header value>,
 	 *         'headers'             => <HTTP header name/value map>
 	 *     )
 	 * @endcode
@@ -519,13 +520,11 @@ 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.
@@ -549,8 +548,14 @@ 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 );
@@ -683,6 +688,8 @@ 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 array $params
 	 * $params include:
@@ -710,7 +717,9 @@ 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.
+	 *
+	 * 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:
@@ -740,6 +749,9 @@ abstract class FileBackend {
 	 * access to the storage user representing end-users in web requests.
 	 * This essentially can undo the result of secure() calls.
 	 *
+	 * 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
@@ -797,7 +809,9 @@ abstract class FileBackend {
 	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 new ScopedCallback( function() use ( $old ) {
+				ignore_user_abort( $old );
+			} );
 		}
 		return null;
 	}
@@ -1029,7 +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
@@ -1047,7 +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
@@ -1062,7 +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
@@ -1082,10 +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 );
@@ -1096,9 +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
 	 */
@@ -1131,10 +1155,11 @@ abstract class FileBackend {
 	 * Callers should consider using getScopedFileLocks() instead.
 	 *
 	 * @param array $paths Storage paths
-	 * @param $type integer LockManager::LOCK_* constant
+	 * @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 );
 	}
 
@@ -1142,10 +1167,11 @@ abstract class FileBackend {
 	 * Unlock the files at the given storage paths in the backend.
 	 *
 	 * @param array $paths Storage paths
-	 * @param $type integer LockManager::LOCK_* constant
+	 * @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 );
 	}
 
@@ -1157,12 +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 array $paths 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 );
 	}
 
@@ -1178,7 +1213,7 @@ abstract class FileBackend {
 	 * @see FileBackend::doOperations()
 	 *
 	 * @param array $ops List of file operations to FileBackend::doOperations()
-	 * @param $status Status Status to update on lock/unlock
+	 * @param Status $status Status to update on lock/unlock
 	 * @return Array List of ScopedFileLocks or null values
 	 * @since 1.20
 	 */
@@ -1219,7 +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 ) {
@@ -1231,7 +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 ) {
@@ -1253,7 +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 ) {
@@ -1274,7 +1309,7 @@ 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 ) {
@@ -1286,7 +1321,7 @@ abstract class FileBackend {
 	/**
 	 * Get the final extension from a storage or FS path
 	 *
-	 * @param $path string
+	 * @param string $path
 	 * @return string
 	 */
 	final public static function extensionFromPath( $path ) {
@@ -1297,7 +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
 	 */
@@ -1363,3 +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 d790a996..be8a2076 100644
--- a/includes/filebackend/FileBackendGroup.php
+++ b/includes/filebackend/FileBackendGroup.php
@@ -95,17 +95,17 @@ class FileBackendGroup {
 				: 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}-transcoded"   => $transcodedDir,
+					"{$repoName}-public" => "{$directory}",
+					"{$repoName}-thumb" => $thumbDir,
+					"{$repoName}-transcoded" => $transcodedDir,
 					"{$repoName}-deleted" => $deletedDir,
-					"{$repoName}-temp"    => "{$directory}/temp"
+					"{$repoName}-temp" => "{$directory}/temp"
 				),
-				'fileMode'       => $fileMode,
+				'fileMode' => $fileMode,
 			);
 		}
 
@@ -116,7 +116,7 @@ class FileBackendGroup {
 	/**
 	 * Register an array of file backend configurations
 	 *
-	 * @param $configs Array
+	 * @param Array $configs
 	 * @return void
 	 * @throws MWException
 	 */
@@ -135,8 +135,8 @@ class FileBackendGroup {
 
 			unset( $config['class'] ); // backend won't need this
 			$this->backends[$name] = array(
-				'class'    => $class,
-				'config'   => $config,
+				'class' => $class,
+				'config' => $config,
 				'instance' => null
 			);
 		}
@@ -145,7 +145,7 @@ class FileBackendGroup {
 	/**
 	 * Get the backend object with a given name
 	 *
-	 * @param $name string
+	 * @param string $name
 	 * @return FileBackend
 	 * @throws MWException
 	 */
@@ -165,7 +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
 	 */
@@ -180,7 +180,7 @@ 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 ) {
diff --git a/includes/filebackend/FileBackendMultiWrite.php b/includes/filebackend/FileBackendMultiWrite.php
index 939315d1..97584a71 100644
--- a/includes/filebackend/FileBackendMultiWrite.php
+++ b/includes/filebackend/FileBackendMultiWrite.php
@@ -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
 			}
@@ -177,6 +171,7 @@ 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 unexpected errors
@@ -304,11 +299,11 @@ 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 ) {
+			$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 ) {
@@ -316,15 +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 ) ) );
 				}
 			}
@@ -366,7 +377,7 @@ class FileBackendMultiWrite extends FileBackend {
 	 * for a set of operations with that of a given internal backend.
 	 *
 	 * @param array $ops List of file operation arrays
-	 * @param $backend FileBackendStore
+	 * @param FileBackendStore $backend
 	 * @return Array
 	 */
 	protected function substOpBatchPaths( array $ops, FileBackendStore $backend ) {
@@ -387,7 +398,7 @@ class FileBackendMultiWrite extends FileBackend {
 	 * Same as substOpBatchPaths() but for a single operation
 	 *
 	 * @param array $ops File operation array
-	 * @param $backend FileBackendStore
+	 * @param FileBackendStore $backend
 	 * @return Array
 	 */
 	protected function substOpPaths( array $ops, FileBackendStore $backend ) {
@@ -399,7 +410,7 @@ class FileBackendMultiWrite extends FileBackend {
 	 * Substitute the backend of storage paths with an internal backend's name
 	 *
 	 * @param array|string $paths List of paths or single string path
-	 * @param $backend FileBackendStore
+	 * @param FileBackendStore $backend
 	 * @return Array|string
 	 */
 	protected function substPaths( $paths, FileBackendStore $backend ) {
@@ -424,10 +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...
@@ -457,14 +464,10 @@ class FileBackendMultiWrite extends FileBackend {
 	 * @return bool Path container should have dir changes pushed to all backends
 	 */
 	protected function replicateContainerDirChanges( $path ) {
-		list( , $shortCont,  ) = 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'] );
@@ -477,11 +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'] );
@@ -494,11 +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'] );
@@ -511,11 +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'] );
@@ -528,62 +516,32 @@ 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
-	 * @return bool|null
-	 */
 	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::getFileContentsMulti()
-	 * @param $params array
-	 * @return bool|string
-	 */
 	public function getFileContentsMulti( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		$contentsM = $this->backends[$this->masterIndex]->getFileContentsMulti( $realParams );
@@ -595,41 +553,21 @@ class FileBackendMultiWrite extends FileBackend {
 		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::getLocalReferenceMulti()
-	 * @param $params array
-	 * @return FSFile|null
-	 */
 	public function getLocalReferenceMulti( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		$fsFilesM = $this->backends[$this->masterIndex]->getLocalReferenceMulti( $realParams );
@@ -641,11 +579,6 @@ class FileBackendMultiWrite extends FileBackend {
 		return $fsFiles;
 	}
 
-	/**
-	 * @see FileBackend::getLocalCopyMulti()
-	 * @param $params array
-	 * @return null|TempFSFile
-	 */
 	public function getLocalCopyMulti( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		$tempFilesM = $this->backends[$this->masterIndex]->getLocalCopyMulti( $realParams );
@@ -657,48 +590,26 @@ class FileBackendMultiWrite extends FileBackend {
 		return $tempFiles;
 	}
 
-	/**
-	 * @see FileBackend::getFileHttpUrl()
-	 * @return string|null
-	 */
 	public function getFileHttpUrl( array $params ) {
 		$realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 		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;
@@ -706,19 +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 3f1d1857..0921e99f 100644
--- a/includes/filebackend/FileBackendStore.php
+++ b/includes/filebackend/FileBackendStore.php
@@ -38,28 +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->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( 300 );
-		$this->expensiveCache = new ProcessCacheLRU( 5 );
+		$this->cheapCache = new ProcessCacheLRU( self::CACHE_CHEAP_SIZE );
+		$this->expensiveCache = new ProcessCacheLRU( self::CACHE_EXPENSIVE_SIZE );
 	}
 
 	/**
@@ -79,7 +94,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * 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 );
@@ -92,7 +107,6 @@ abstract class FileBackendStore extends FileBackend {
 	 * $params include:
 	 *   - content     : the raw file contents
 	 *   - dst         : destination storage path
-	 *   - disposition : Content-Disposition header value for the destination
 	 *   - 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
@@ -104,8 +118,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * @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() );
@@ -116,8 +129,6 @@ abstract class FileBackendStore extends FileBackend {
 				$this->deleteFileCache( $params['dst'] ); // persistent cache
 			}
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -135,7 +146,6 @@ abstract class FileBackendStore extends FileBackend {
 	 * $params include:
 	 *   - src         : source path on disk
 	 *   - dst         : destination storage path
-	 *   - disposition : Content-Disposition header value for the destination
 	 *   - 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
@@ -147,8 +157,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * @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() );
@@ -159,8 +168,6 @@ abstract class FileBackendStore extends FileBackend {
 				$this->deleteFileCache( $params['dst'] ); // persistent cache
 			}
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -179,7 +186,7 @@ abstract class FileBackendStore extends FileBackend {
 	 *   - src                 : source storage path
 	 *   - dst                 : destination storage path
 	 *   - ignoreMissingSource : do nothing if the source file does not exist
-	 *   - disposition         : Content-Disposition header value for the destination
+	 *   - 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.
@@ -190,15 +197,12 @@ abstract class FileBackendStore extends FileBackend {
 	 * @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 ( !isset( $params['dstExists'] ) || $params['dstExists'] ) {
 			$this->deleteFileCache( $params['dst'] ); // persistent cache
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -223,13 +227,10 @@ abstract class FileBackendStore extends FileBackend {
 	 * @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;
 	}
 
@@ -248,7 +249,7 @@ abstract class FileBackendStore extends FileBackend {
 	 *   - src                 : source storage path
 	 *   - dst                 : destination storage path
 	 *   - ignoreMissingSource : do nothing if the source file does not exist
-	 *   - disposition         : Content-Disposition header value for the destination
+	 *   - 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.
@@ -259,16 +260,13 @@ abstract class FileBackendStore extends FileBackend {
 	 * @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 ( !isset( $params['dstExists'] ) || $params['dstExists'] ) {
 			$this->deleteFileCache( $params['dst'] ); // persistent cache
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -278,10 +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
 		}
@@ -294,7 +294,6 @@ abstract class FileBackendStore extends FileBackend {
 	 *
 	 * $params include:
 	 *   - src           : source storage path
-	 *   - disposition   : Content-Disposition header value for the destination
 	 *   - 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
@@ -304,13 +303,14 @@ abstract class FileBackendStore extends FileBackend {
 	 * @return Status
 	 */
 	final public function describeInternal( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
-		$status = $this->doDescribeInternal( $params );
-		$this->clearCache( array( $params['src'] ) );
-		$this->deleteFileCache( $params['src'] ); // persistent cache
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
+		$section = new ProfileSection( __METHOD__ . "-{$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;
 	}
 
@@ -333,13 +333,8 @@ abstract class FileBackendStore extends FileBackend {
 		return Status::newGood();
 	}
 
-	/**
-	 * @see FileBackend::concatenate()
-	 * @return Status
-	 */
 	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
@@ -355,8 +350,6 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -426,20 +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
 		}
 
@@ -453,8 +439,6 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -466,20 +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
 		}
 
@@ -493,8 +470,6 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -506,20 +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
 		}
 
@@ -533,8 +501,6 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -546,13 +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
@@ -570,8 +531,6 @@ abstract class FileBackendStore extends FileBackend {
 		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
 		}
 
@@ -579,8 +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
 		}
 
@@ -596,8 +553,6 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -609,56 +564,30 @@ 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', self::CACHE_TTL ) ) {
 			$this->primeFileCache( array( $path ) ); // check persistent cache
@@ -669,14 +598,10 @@ abstract class FileBackendStore extends FileBackend {
 			// value was in fact fetched with the latest available data.
 			if ( is_array( $stat ) ) {
 				if ( !$latest || $stat['latest'] ) {
-					wfProfileOut( __METHOD__ . '-' . $this->name );
-					wfProfileOut( __METHOD__ );
 					return $stat;
 				}
 			} elseif ( in_array( $stat, array( 'NOT_EXIST', 'NOT_EXIST_LATEST' ) ) ) {
 				if ( !$latest || $stat === 'NOT_EXIST_LATEST' ) {
-					wfProfileOut( __METHOD__ . '-' . $this->name );
-					wfProfileOut( __METHOD__ );
 					return false;
 				}
 			}
@@ -696,12 +621,12 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		} 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;
 	}
 
@@ -710,19 +635,12 @@ abstract class FileBackendStore extends FileBackend {
 	 */
 	abstract protected function doGetFileStat( array $params );
 
-	/**
-	 * @see FileBackend::getFileContentsMulti()
-	 * @return Array
-	 */
 	public function getFileContentsMulti( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 
 		$params = $this->setConcurrencyFlags( $params );
 		$contents = $this->doGetFileContentsMulti( $params );
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $contents;
 	}
 
@@ -740,25 +658,18 @@ abstract class FileBackendStore extends FileBackend {
 		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', 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'];
 			}
 		}
@@ -768,8 +679,6 @@ abstract class FileBackendStore extends FileBackend {
 		wfProfileOut( __METHOD__ . '-miss-' . $this->name );
 		wfProfileOut( __METHOD__ . '-miss' );
 		$this->cheapCache->set( $path, 'sha1', array( 'hash' => $hash, 'latest' => $latest ) );
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $hash;
 	}
 
@@ -786,27 +695,15 @@ 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::getLocalReferenceMulti()
-	 * @return Array
-	 */
 	final public function getLocalReferenceMulti( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 
 		$params = $this->setConcurrencyFlags( $params );
 
@@ -836,8 +733,6 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $fsFiles;
 	}
 
@@ -849,19 +744,12 @@ abstract class FileBackendStore extends FileBackend {
 		return $this->doGetLocalCopyMulti( $params );
 	}
 
-	/**
-	 * @see FileBackend::getLocalCopyMulti()
-	 * @return Array
-	 */
 	final public function getLocalCopyMulti( array $params ) {
-		wfProfileIn( __METHOD__ );
-		wfProfileIn( __METHOD__ . '-' . $this->name );
+		$section = new ProfileSection( __METHOD__ . "-{$this->name}" );
 
 		$params = $this->setConcurrencyFlags( $params );
 		$tmpFiles = $this->doGetLocalCopyMulti( $params );
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $tmpFiles;
 	}
 
@@ -879,13 +767,8 @@ abstract class FileBackendStore extends FileBackend {
 		return null; // not supported
 	}
 
-	/**
-	 * @see FileBackend::streamFile()
-	 * @return Status
-	 */
 	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 );
@@ -916,8 +799,6 @@ abstract class FileBackendStore extends FileBackend {
 			$status->fatal( 'backend-fail-stream', $params['src'] );
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -938,10 +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 ) {
@@ -976,10 +853,6 @@ abstract class FileBackendStore extends FileBackend {
 	 */
 	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
@@ -1009,10 +882,6 @@ abstract class FileBackendStore extends FileBackend {
 	 */
 	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
@@ -1055,13 +924,13 @@ abstract class FileBackendStore extends FileBackend {
 	 */
 	final public function getOperationsInternal( array $ops ) {
 		$supportedOps = array(
-			'store'    => 'StoreFileOp',
-			'copy'     => 'CopyFileOp',
-			'move'     => 'MoveFileOp',
-			'delete'   => 'DeleteFileOp',
-			'create'   => 'CreateFileOp',
+			'store' => 'StoreFileOp',
+			'copy' => 'CopyFileOp',
+			'move' => 'MoveFileOp',
+			'delete' => 'DeleteFileOp',
+			'create' => 'CreateFileOp',
 			'describe' => 'DescribeFileOp',
-			'null'     => 'NullFileOp'
+			'null' => 'NullFileOp'
 		);
 
 		$performOps = array(); // array of FileOp objects
@@ -1084,12 +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.
-	 * All returned paths are normalized.
+	 * 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 array $performOps List of FileOp objects
-	 * @return Array ('sh' => list of paths, 'ex' => list of paths)
+	 * @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...
@@ -1103,28 +973,19 @@ 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...
@@ -1138,11 +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
 			}
 		}
@@ -1164,19 +1022,11 @@ abstract class FileBackendStore extends FileBackend {
 		$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...
@@ -1186,7 +1036,7 @@ abstract class FileBackendStore extends FileBackend {
 		$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)
@@ -1195,8 +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"
@@ -1230,8 +1078,6 @@ abstract class FileBackendStore extends FileBackend {
 			}
 		}
 
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $status;
 	}
 
@@ -1245,8 +1091,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * @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." );
@@ -1258,8 +1103,6 @@ abstract class FileBackendStore extends FileBackend {
 		foreach ( $fileOpHandles as $fileOpHandle ) {
 			$fileOpHandle->closeResources();
 		}
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 		return $res;
 	}
 
@@ -1277,15 +1120,20 @@ abstract class FileBackendStore extends FileBackend {
 	}
 
 	/**
-	 * Strip long HTTP headers from a file operation
+	 * 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 ) {
-		if ( isset( $op['headers'] ) ) {
+		static $longs = array( 'Content-Disposition' );
+		if ( isset( $op['headers'] ) ) { // op sets HTTP headers
 			foreach ( $op['headers'] as $name => $value ) {
-				if ( strlen( $name ) > 255 || strlen( $value ) > 255 ) {
+				$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 ) ) {
@@ -1296,9 +1144,6 @@ abstract class FileBackendStore extends FileBackend {
 		return $op;
 	}
 
-	/**
-	 * @see FileBackend::preloadCache()
-	 */
 	final public function preloadCache( array $paths ) {
 		$fullConts = array(); // full container names
 		foreach ( $paths as $path ) {
@@ -1310,9 +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 );
@@ -1353,7 +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 ) {
@@ -1375,7 +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 ) {
@@ -1405,16 +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 );
@@ -1474,7 +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 ) {
@@ -1494,7 +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 ) {
@@ -1512,7 +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 ) {
@@ -1528,7 +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 ) {
@@ -1563,10 +1411,11 @@ abstract class FileBackendStore extends FileBackend {
 	 * Set the cached info for a container
 	 *
 	 * @param string $container Resolved container name
-	 * @param $val mixed Information to cache
+	 * @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 );
 	}
 
 	/**
@@ -1574,6 +1423,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * The cache key is salted for a while to prevent race conditions.
 	 *
 	 * @param string $container Resolved container name
+	 * @return void
 	 */
 	final protected function deleteContainerCache( $container ) {
 		if ( !$this->memCache->set( $this->containerCacheKey( $container ), 'PURGED', 300 ) ) {
@@ -1586,12 +1436,11 @@ abstract class FileBackendStore extends FileBackend {
 	 * 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)
@@ -1623,9 +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__ );
 	}
 
 	/**
@@ -1654,14 +1500,17 @@ abstract class FileBackendStore extends FileBackend {
 	 * salting for the case when a file is created at a path were there was none before.
 	 *
 	 * @param string $path Storage path
-	 * @param $val mixed Information to cache
+	 * @param array $val Stat information to cache
+	 * @return void
 	 */
-	final protected function setFileCache( $path, $val ) {
+	final protected function setFileCache( $path, array $val ) {
 		$path = FileBackend::normalizeStoragePath( $path );
 		if ( $path === null ) {
 			return; // invalid storage path
 		}
-		$this->memCache->add( $this->fileCacheKey( $path ), $val, 7*86400 );
+		$age = time() - wfTimestamp( TS_UNIX, $val['mtime'] );
+		$ttl = min( 7 * 86400, max( 300, floor( .1 * $age ) ) );
+		$this->memCache->add( $this->fileCacheKey( $path ), $val, $ttl );
 	}
 
 	/**
@@ -1671,6 +1520,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * a file is created at a path were there was none before.
 	 *
 	 * @param string $path Storage path
+	 * @return void
 	 */
 	final protected function deleteFileCache( $path ) {
 		$path = FileBackend::normalizeStoragePath( $path );
@@ -1691,8 +1541,7 @@ abstract class FileBackendStore extends FileBackend {
 	 * @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)
@@ -1726,9 +1575,6 @@ abstract class FileBackendStore extends FileBackend {
 				}
 			}
 		}
-
-		wfProfileOut( __METHOD__ . '-' . $this->name );
-		wfProfileOut( __METHOD__ );
 	}
 
 	/**
@@ -1750,6 +1596,18 @@ abstract class FileBackendStore extends FileBackend {
 		}
 		return $opts;
 	}
+
+	/**
+	 * 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() );
+	}
 }
 
 /**
@@ -1786,26 +1644,20 @@ 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 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
@@ -1817,142 +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 );
-	}
 
-	/**
-	 * @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;
-			}
-		}
+		parent::__construct( $iter );
 	}
 
-	/**
-	 * 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 string $container Resolved container name
-	 * @param string $dir Resolved path relative to container
-	 * @param array $params
-	 * @return Traversable|Array|null
+	 * @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;
+		}
 	}
 }
 
@@ -1960,11 +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 bb0ab578..fe833084 100644
--- a/includes/filebackend/FileOp.php
+++ b/includes/filebackend/FileOp.php
@@ -46,7 +46,7 @@ abstract class FileOp {
 
 	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 */
@@ -55,17 +55,19 @@ 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] ) ) {
+				// 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'." );
@@ -73,6 +75,7 @@ abstract class FileOp {
 		}
 		foreach ( $optional as $name ) {
 			if ( isset( $params[$name] ) ) {
+				// Normalize paths so the paths to the same file have the same string
 				$this->params[$name] = self::normalizeAnyStoragePaths( $params[$name] );
 			}
 		}
@@ -82,7 +85,7 @@ abstract class FileOp {
 	/**
 	 * Normalize $item or anything in $item that is a valid storage path
 	 *
-	 * @param $item string|array
+	 * @param string $item|array
 	 * @return string|Array
 	 */
 	protected function normalizeAnyStoragePaths( $item ) {
@@ -102,7 +105,7 @@ abstract class FileOp {
 	/**
 	 * Normalize a string if it is a valid storage path
 	 *
-	 * @param $path string
+	 * @param string $path
 	 * @return string
 	 */
 	protected static function normalizeIfValidStoragePath( $path ) {
@@ -116,7 +119,7 @@ abstract class FileOp {
 	/**
 	 * Set the batch UUID this operation belongs to
 	 *
-	 * @param $batchId string
+	 * @param string $batchId
 	 * @return void
 	 */
 	final public function setBatchId( $batchId ) {
@@ -126,7 +129,7 @@ abstract class FileOp {
 	/**
 	 * 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 ) {
@@ -209,22 +212,22 @@ abstract class FileOp {
 		$pathsUsed = array_merge( $this->storagePathsRead(), $this->storagePathsChanged() );
 		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]
 				);
 			}
@@ -237,7 +240,7 @@ abstract class FileOp {
 	 * 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 ) {
@@ -314,7 +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 ) {
@@ -341,10 +344,10 @@ abstract class FileOp {
 
 	/**
 	 * Check for errors with regards to the destination file already existing.
-	 * Also set the destExists, 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 ) {
@@ -354,7 +357,7 @@ abstract class FileOp {
 		if ( $this->sourceSha1 === null ) { // file in storage?
 			$this->sourceSha1 = $this->fileSha1( $this->params['src'], $predicates );
 		}
-		$this->destSameAsSource = false;
+		$this->overwriteSameCase = false;
 		$this->destExists = $this->fileExists( $this->params['dst'], $predicates );
 		if ( $this->destExists ) {
 			if ( $this->getParam( 'overwrite' ) ) {
@@ -368,7 +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 {
@@ -381,7 +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
 	 */
@@ -393,7 +396,7 @@ abstract class FileOp {
 	 * Check if a file will exist in storage when this operation is attempted
 	 *
 	 * @param string $source Storage path
-	 * @param $predicates Array
+	 * @param Array $predicates
 	 * @return bool
 	 */
 	final protected function fileExists( $source, array $predicates ) {
@@ -409,7 +412,7 @@ abstract class FileOp {
 	 * Get the SHA-1 of a file in storage when this operation is attempted
 	 *
 	 * @param string $source Storage path
-	 * @param $predicates Array
+	 * @param Array $predicates
 	 * @return string|bool False on failure
 	 */
 	final protected function fileSha1( $source, array $predicates ) {
@@ -435,7 +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 ) {
@@ -457,7 +460,7 @@ abstract class FileOp {
 class CreateFileOp extends FileOp {
 	protected function allowedParams() {
 		return array( array( 'content', 'dst' ),
-			array( 'overwrite', 'overwriteSame', 'disposition', 'headers' ) );
+			array( 'overwrite', 'overwriteSame', 'headers' ) );
 	}
 
 	protected function doPrecheck( array &$predicates ) {
@@ -485,27 +488,18 @@ class CreateFileOp extends FileOp {
 		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return Status
-	 */
 	protected function doAttempt() {
-		if ( !$this->destSameAsSource ) {
+		if ( !$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() {
 		return wfBaseConvert( sha1( $this->params['content'] ), 16, 36, 31 );
 	}
 
-	/**
-	 * @return array
-	 */
 	public function storagePathsChanged() {
 		return array( $this->params['dst'] );
 	}
@@ -516,18 +510,11 @@ class CreateFileOp extends FileOp {
  * Parameters for this operation are outlined in FileBackend::doOperations().
  */
 class StoreFileOp extends FileOp {
-	/**
-	 * @return array
-	 */
 	protected function allowedParams() {
 		return array( array( 'src', 'dst' ),
-			array( 'overwrite', 'overwriteSame', 'disposition', 'headers' ) );
+			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
@@ -557,20 +544,14 @@ class StoreFileOp extends FileOp {
 		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return Status
-	 */
 	protected function doAttempt() {
-		// Store the file at the destination
-		if ( !$this->destSameAsSource ) {
+		if ( !$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() {
 		wfSuppressWarnings();
 		$hash = sha1_file( $this->params['src'] );
@@ -591,18 +572,11 @@ class StoreFileOp 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', 'ignoreMissingSource', '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
@@ -634,30 +608,26 @@ 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
-	 */
 	public function storagePathsRead() {
 		return array( $this->params['src'] );
 	}
 
-	/**
-	 * @return array
-	 */
 	public function storagePathsChanged() {
 		return array( $this->params['dst'] );
 	}
@@ -668,18 +638,11 @@ 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', 'ignoreMissingSource', '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
@@ -713,34 +676,34 @@ 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
-	 */
 	public function storagePathsRead() {
 		return array( $this->params['src'] );
 	}
 
-	/**
-	 * @return array
-	 */
 	public function storagePathsChanged() {
 		return array( $this->params['src'], $this->params['dst'] );
 	}
@@ -751,17 +714,10 @@ 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' ) );
 	}
 
-	/**
-	 * @param $predicates array
-	 * @return Status
-	 */
 	protected function doPrecheck( array &$predicates ) {
 		$status = Status::newGood();
 		// Check if the source file exists
@@ -788,17 +744,11 @@ class DeleteFileOp extends FileOp {
 		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return Status
-	 */
 	protected function doAttempt() {
 		// Delete the source file
 		return $this->backend->deleteInternal( $this->setFlags( $this->params ) );
 	}
 
-	/**
-	 * @return array
-	 */
 	public function storagePathsChanged() {
 		return array( $this->params['src'] );
 	}
@@ -809,17 +759,10 @@ class DeleteFileOp extends FileOp {
  * Parameters for this operation are outlined in FileBackend::doOperations().
  */
 class DescribeFileOp extends FileOp {
-	/**
-	 * @return array
-	 */
 	protected function allowedParams() {
-		return array( array( 'src' ), array( 'disposition', 'headers' ) );
+		return array( array( 'src' ), array( 'headers' ) );
 	}
 
-	/**
-	 * @param $predicates array
-	 * @return Status
-	 */
 	protected function doPrecheck( array &$predicates ) {
 		$status = Status::newGood();
 		// Check if the source file exists
@@ -840,17 +783,11 @@ class DescribeFileOp extends FileOp {
 		return $status; // safe to call attempt()
 	}
 
-	/**
-	 * @return Status
-	 */
 	protected function doAttempt() {
 		// Update the source file's metadata
 		return $this->backend->describeInternal( $this->setFlags( $this->params ) );
 	}
 
-	/**
-	 * @return array
-	 */
 	public function storagePathsChanged() {
 		return array( $this->params['src'] );
 	}
diff --git a/includes/filebackend/FileOpBatch.php b/includes/filebackend/FileOpBatch.php
index fc51d78a..785c0bc9 100644
--- a/includes/filebackend/FileOpBatch.php
+++ b/includes/filebackend/FileOpBatch.php
@@ -51,7 +51,7 @@ class FileOpBatch {
 	 *
 	 * @param array $performOps List of FileOp operations
 	 * @param array $opts Batch operation options
-	 * @param $journal FileJournal Journal to log operations to
+	 * @param FileJournal $journal Journal to log operations to
 	 * @return Status
 	 */
 	public static function attempt( array $performOps, array $opts, FileJournal $journal ) {
@@ -145,8 +145,8 @@ 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 runParallelBatches( array $pPerformOps, Status $status ) {
diff --git a/includes/filebackend/README b/includes/filebackend/README
index 6ab54810..569f3376 100644
--- a/includes/filebackend/README
+++ b/includes/filebackend/README
@@ -47,7 +47,7 @@ directories. See FileBackend.php for full documentation for each function.
 The following basic operations are supported for reading from a backend:
 
 On files:
-* state a file for basic information (timestamp, size)
+* 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
diff --git a/includes/filebackend/SwiftFileBackend.php b/includes/filebackend/SwiftFileBackend.php
index 0f3d97a3..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).
@@ -104,7 +104,7 @@ class SwiftFileBackend extends FileBackendStore {
 	 */
 	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
@@ -132,7 +132,7 @@ 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;
@@ -172,10 +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 ) {
@@ -194,6 +190,18 @@ class SwiftFileBackend extends FileBackendStore {
 	}
 
 	/**
+	 * @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
 	 */
@@ -211,10 +219,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $res;
 	}
 
-	/**
-	 * @see FileBackendStore::doCreateInternal()
-	 * @return Status
-	 */
 	protected function doCreateInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -248,17 +252,10 @@ class SwiftFileBackend extends FileBackendStore {
 			// 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 += $params['headers'];
+				$obj->headers += $this->sanitizeHdrs( $params['headers'] );
 			}
 			if ( !empty( $params['async'] ) ) { // deferred
 				$op = $obj->write_async( $params['content'] );
@@ -290,10 +287,6 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doStoreInternal()
-	 * @return Status
-	 */
 	protected function doStoreInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -333,17 +326,10 @@ class SwiftFileBackend extends FileBackendStore {
 			// 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 += $params['headers'];
+				$obj->headers += $this->sanitizeHdrs( $params['headers'] );
 			}
 			if ( !empty( $params['async'] ) ) { // deferred
 				wfSuppressWarnings();
@@ -387,10 +373,6 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doCopyInternal()
-	 * @return Status
-	 */
 	protected function doCopyInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -424,8 +406,9 @@ 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 );
@@ -459,10 +442,6 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doMoveInternal()
-	 * @return Status
-	 */
 	protected function doMoveInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -497,8 +476,9 @@ 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 );
@@ -534,10 +514,6 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doDeleteInternal()
-	 * @return Status
-	 */
 	protected function doDeleteInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -590,10 +566,6 @@ class SwiftFileBackend extends FileBackendStore {
 		}
 	}
 
-	/**
-	 * @see FileBackendStore::doDescribeInternal()
-	 * @return Status
-	 */
 	protected function doDescribeInternal( array $params ) {
 		$status = Status::newGood();
 
@@ -603,19 +575,15 @@ class SwiftFileBackend extends FileBackendStore {
 			return $status;
 		}
 
-		$hdrs = isset( $params['headers'] ) ? $params['headers'] : array();
-		// Set the Content-Disposition header if requested
-		if ( isset( $params['disposition'] ) ) {
-			$hdrs['Content-Disposition'] = $this->truncDisp( $params['disposition'] );
-		}
-
 		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...
-			$srcObj->headers = $hdrs + $srcObj->headers;
+			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 ) {
@@ -631,10 +599,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doPrepareInternal()
-	 * @return Status
-	 */
 	protected function doPrepareInternal( $fullCont, $dir, array $params ) {
 		$status = Status::newGood();
 
@@ -748,10 +712,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doCleanInternal()
-	 * @return Status
-	 */
 	protected function doCleanInternal( $fullCont, $dir, array $params ) {
 		$status = Status::newGood();
 
@@ -787,10 +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 ) {
@@ -805,8 +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'  => $srcObj->getMetadataValue( 'Sha1base36' )
+				'size' => (int)$srcObj->content_length,
+				'sha1' => $srcObj->getMetadataValue( 'Sha1base36' )
 			);
 		} catch ( NoSuchContainerException $e ) {
 		} catch ( NoSuchObjectException $e ) {
@@ -821,7 +777,7 @@ class SwiftFileBackend extends FileBackendStore {
 	/**
 	 * Fill in any missing object metadata and save it to Swift
 	 *
-	 * @param $obj CF_Object
+	 * @param CF_Object $obj
 	 * @param string $path Storage path to object
 	 * @return bool Success
 	 * @throws Exception cloudfiles exceptions
@@ -852,10 +808,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return false; // failed
 	}
 
-	/**
-	 * @see FileBackendStore::doGetFileContentsMulti()
-	 * @return Array
-	 */
 	protected function doGetFileContentsMulti( array $params ) {
 		$contents = array();
 
@@ -965,24 +917,25 @@ class SwiftFileBackend extends FileBackendStore {
 	 * @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 $limit integer Max number of items to list
-	 * @param array $params Includes flag for 'topOnly'
-	 * @return Array List of relative paths of dirs directly under $dir
+	 * @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 '/'
 					}
@@ -1013,6 +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 {
@@ -1022,9 +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;
 	}
 
@@ -1038,33 +992,49 @@ class SwiftFileBackend extends FileBackendStore {
 	 * @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 $limit integer Max number of items to list
-	 * @param array $params Includes flag for 'topOnly'
-	 * @return Array List of relative paths of files under $dir
+	 * @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 {
@@ -1074,29 +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();
 
@@ -1128,10 +1126,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $status;
 	}
 
-	/**
-	 * @see FileBackendStore::doGetLocalCopyMulti()
-	 * @return null|TempFSFile
-	 */
 	protected function doGetLocalCopyMulti( array $params ) {
 		$tmpFiles = array();
 
@@ -1201,10 +1195,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return $tmpFiles;
 	}
 
-	/**
-	 * @see FileBackendStore::getFileHttpUrl()
-	 * @return string|null
-	 */
 	public function getFileHttpUrl( array $params ) {
 		if ( $this->swiftTempUrlKey != '' ||
 			( $this->rgwS3AccessKey != '' && $this->rgwS3SecretKey != '' ) )
@@ -1237,8 +1227,8 @@ class SwiftFileBackend extends FileBackendStore {
 						str_replace( '/swift/v1', '', // S3 API is the rgw default
 							$sContObj->cfs_http->getStorageUrl() . $spath ),
 						array(
-							'Signature'      => $signature,
-							'Expires'        => $expires,
+							'Signature' => $signature,
+							'Expires' => $expires,
 							'AWSAccessKeyId' => $this->rgwS3AccessKey )
 					);
 				}
@@ -1250,10 +1240,6 @@ class SwiftFileBackend extends FileBackendStore {
 		return null;
 	}
 
-	/**
-	 * @see FileBackendStore::directoriesAreVirtual()
-	 * @return bool
-	 */
 	protected function directoriesAreVirtual() {
 		return true;
 	}
@@ -1274,10 +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();
 
@@ -1314,7 +1296,7 @@ class SwiftFileBackend extends FileBackendStore {
 	 *                           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.
+	 *                           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:
@@ -1325,7 +1307,7 @@ 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 CF_Container $contObj Swift container
 	 * @param array $readGrps List of read access routes
 	 * @param array $writeGrps List of write access routes
 	 * @return Status
@@ -1395,12 +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
@@ -1433,7 +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 ) {
@@ -1496,10 +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
@@ -1517,9 +1495,9 @@ 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 Exception $e
+	 * @param Status $status|null
+	 * @param string $func
 	 * @param array $params
 	 * @return void
 	 */
@@ -1554,7 +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;
@@ -1586,7 +1572,7 @@ abstract class SwiftFileBackendList implements Iterator {
 	const PAGE_SIZE = 9000; // file listing buffer size
 
 	/**
-	 * @param $backend SwiftFileBackend
+	 * @param SwiftFileBackend $backend
 	 * @param string $fullCont Resolved container name
 	 * @param string $dir Resolved directory relative to container
 	 * @param array $params
@@ -1660,10 +1646,10 @@ abstract class SwiftFileBackendList implements Iterator {
 	 *
 	 * @param string $container Resolved container name
 	 * @param string $dir Resolved path relative to container
-	 * @param $after string|null
-	 * @param $limit integer
+	 * @param string $after|null
+	 * @param integer $limit
 	 * @param array $params
-	 * @return Traversable|Array|null Returns null on failure
+	 * @return Traversable|Array
 	 */
 	abstract protected function pageFromList( $container, $dir, &$after, $limit, array $params );
 }
@@ -1682,7 +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 );
@@ -1703,7 +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 11e125c1..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 = '' ) {
@@ -81,7 +81,7 @@ class TempFSFile extends FSFile {
 	/**
 	 * Clean up the temporary file only after an object goes out of scope
 	 *
-	 * @param $object Object
+	 * @param Object $object
 	 * @return TempFSFile This object
 	 */
 	public function bind( $object ) {
diff --git a/includes/filebackend/filejournal/DBFileJournal.php b/includes/filebackend/filejournal/DBFileJournal.php
index 73f29a95..9250aa5e 100644
--- a/includes/filebackend/filejournal/DBFileJournal.php
+++ b/includes/filebackend/filejournal/DBFileJournal.php
@@ -65,11 +65,11 @@ 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 )
 			);
 		}
 
diff --git a/includes/filebackend/lockmanager/DBLockManager.php b/includes/filebackend/lockmanager/DBLockManager.php
index f02387dc..3e934ba5 100644
--- a/includes/filebackend/lockmanager/DBLockManager.php
+++ b/includes/filebackend/lockmanager/DBLockManager.php
@@ -110,6 +110,19 @@ abstract class DBLockManager extends QuorumLockManager {
 		$this->session = wfRandomString( 31 );
 	}
 
+	// @TODO: change this code to work in one batch
+	protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
+		$status = Status::newGood();
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doGetLocksOnServer( $lockSrv, $paths, $type ) );
+		}
+		return $status;
+	}
+
+	protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
+		return Status::newGood();
+	}
+
 	/**
 	 * @see QuorumLockManager::isServerUp()
 	 * @return bool
@@ -252,7 +265,7 @@ 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()
@@ -319,14 +332,6 @@ class MySqlLockManager extends DBLockManager {
 	}
 
 	/**
-	 * @see QuorumLockManager::freeLocksOnServer()
-	 * @return Status
-	 */
-	protected function freeLocksOnServer( $lockSrv, array $paths, $type ) {
-		return Status::newGood(); // not supported
-	}
-
-	/**
 	 * @see QuorumLockManager::releaseAllLocks()
 	 * @return Status
 	 */
@@ -361,7 +366,7 @@ class PostgreSqlLockManager extends DBLockManager {
 		self::LOCK_EX => self::LOCK_EX
 	);
 
-	protected function getLocksOnServer( $lockSrv, array $paths, $type ) {
+	protected function doGetLocksOnServer( $lockSrv, array $paths, $type ) {
 		$status = Status::newGood();
 		if ( !count( $paths ) ) {
 			return $status; // nothing to lock
@@ -369,7 +374,9 @@ class PostgreSqlLockManager extends DBLockManager {
 
 		$db = $this->getConnection( $lockSrv ); // checked in isServerUp()
 		$bigints = array_unique( array_map(
-			function( $key ) { return wfBaseConvert( substr( $key, 0, 15 ), 16, 10 ); },
+			function( $key ) {
+				return wfBaseConvert( substr( $key, 0, 15 ), 16, 10 );
+			},
 			array_map( array( $this, 'sha1Base16Absolute' ), $paths )
 		) );
 
@@ -406,14 +413,6 @@ class PostgreSqlLockManager extends DBLockManager {
 	}
 
 	/**
-	 * @see QuorumLockManager::freeLocksOnServer()
-	 * @return Status
-	 */
-	protected function freeLocksOnServer( $lockSrv, array $paths, $type ) {
-		return Status::newGood(); // not supported
-	}
-
-	/**
 	 * @see QuorumLockManager::releaseAllLocks()
 	 * @return Status
 	 */
diff --git a/includes/filebackend/lockmanager/LockManager.php b/includes/filebackend/lockmanager/LockManager.php
index 0512a01b..dad8a624 100644
--- a/includes/filebackend/lockmanager/LockManager.php
+++ b/includes/filebackend/lockmanager/LockManager.php
@@ -56,7 +56,7 @@ abstract class LockManager {
 	protected $domain; // string; domain (usually wiki ID)
 	protected $lockTTL; // integer; maximum time locks can be held
 
-	/* Lock types; stronger locks have higher values */
+	/** 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)
@@ -76,10 +76,10 @@ abstract class LockManager {
 		if ( isset( $config['lockTTL'] ) ) {
 			$this->lockTTL = max( 1, $config['lockTTL'] );
 		} elseif ( PHP_SAPI === 'cli' ) {
-			$this->lockTTL = 2*3600;
+			$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 );
+			$this->lockTTL = max( 5 * 60, 2 * (int)$met );
 		}
 	}
 
@@ -88,11 +88,36 @@ abstract class LockManager {
 	 *
 	 * @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 ) {
+	final public function lock( array $paths, $type = self::LOCK_EX, $timeout = 0 ) {
+		return $this->lockByType( array( $type => $paths ), $timeout );
+	}
+
+	/**
+	 * Lock the resources at the given abstract paths
+	 *
+	 * @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 lockByType( array $pathsByType, $timeout = 0 ) {
 		wfProfileIn( __METHOD__ );
-		$status = $this->doLock( 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;
 	}
@@ -100,13 +125,25 @@ abstract class LockManager {
 	/**
 	 * Unlock the resources at the given abstract paths
 	 *
-	 * @param array $paths List of storage paths
+	 * @param array $paths List of paths
 	 * @param $type integer LockManager::LOCK_* constant
 	 * @return Status
 	 */
 	final public function unlock( array $paths, $type = self::LOCK_EX ) {
+		return $this->unlockByType( array( $type => $paths ) );
+	}
+
+	/**
+	 * Unlock the resources at the given abstract paths
+	 *
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
+	 * @return Status
+	 * @since 1.22
+	 */
+	final public function unlockByType( array $pathsByType ) {
 		wfProfileIn( __METHOD__ );
-		$status = $this->doUnlock( array_unique( $paths ), $this->lockTypeMap[$type] );
+		$pathsByType = $this->normalizePathsByType( $pathsByType );
+		$status = $this->doUnlockByType( $pathsByType );
 		wfProfileOut( __METHOD__ );
 		return $status;
 	}
@@ -136,20 +173,74 @@ abstract class LockManager {
 	}
 
 	/**
+	 * 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 normalizePathsByType( array $pathsByType ) {
+		$res = array();
+		foreach ( $pathsByType as $type => $paths ) {
+			$res[$this->lockTypeMap[$type]] = array_unique( $paths );
+		}
+		return $res;
+	}
+
+	/**
+	 * @see LockManager::lockByType()
+	 * @param array $paths Map of LockManager::LOCK_* constants to lists of paths
+	 * @return Status
+	 * @since 1.22
+	 */
+	protected function doLockByType( array $pathsByType ) {
+		$status = Status::newGood();
+		$lockedByType = array(); // map of (type => paths)
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doLock( $paths, $type ) );
+			if ( $status->isOK() ) {
+				$lockedByType[$type] = $paths;
+			} else {
+				// Release the subset of locks that were acquired
+				foreach ( $lockedByType as $type => $paths ) {
+					$status->merge( $this->doUnlock( $paths, $type ) );
+				}
+				break;
+			}
+		}
+		return $status;
+	}
+
+	/**
 	 * Lock resources with the given keys and lock type
 	 *
-	 * @param array $paths List of storage paths
+	 * @param array $paths List of paths
 	 * @param $type integer LockManager::LOCK_* constant
-	 * @return string
+	 * @return Status
 	 */
 	abstract protected function doLock( array $paths, $type );
 
 	/**
+	 * @see LockManager::unlockByType()
+	 * @param array $paths Map of LockManager::LOCK_* constants to lists of paths
+	 * @return Status
+	 * @since 1.22
+	 */
+	protected function doUnlockByType( array $pathsByType ) {
+		$status = Status::newGood();
+		foreach ( $pathsByType as $type => $paths ) {
+			$status->merge( $this->doUnlock( $paths, $type ) );
+		}
+		return $status;
+	}
+
+	/**
 	 * Unlock resources with the given keys and lock type
 	 *
-	 * @param array $paths List of storage paths
+	 * @param array $paths List of paths
 	 * @param $type integer LockManager::LOCK_* constant
-	 * @return string
+	 * @return Status
 	 */
 	abstract protected function doUnlock( array $paths, $type );
 }
@@ -159,22 +250,10 @@ abstract class 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 ac0bd49b..9aff2415 100644
--- a/includes/filebackend/lockmanager/LockManagerGroup.php
+++ b/includes/filebackend/lockmanager/LockManagerGroup.php
@@ -97,8 +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
 			);
 		}
diff --git a/includes/filebackend/lockmanager/MemcLockManager.php b/includes/filebackend/lockmanager/MemcLockManager.php
index fafc588a..5eab03ee 100644
--- a/includes/filebackend/lockmanager/MemcLockManager.php
+++ b/includes/filebackend/lockmanager/MemcLockManager.php
@@ -88,11 +88,44 @@ class MemcLockManager extends QuorumLockManager {
 		$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;
+	}
+
 	/**
 	 * @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 );
@@ -145,7 +178,7 @@ class MemcLockManager extends QuorumLockManager {
 			foreach ( $paths as $path ) {
 				$locksKey = $this->recordKeyForPath( $path );
 				$locksHeld = $lockRecords[$locksKey];
-				$ok = $memc->set( $locksKey, $locksHeld, 7*86400 );
+				$ok = $memc->set( $locksKey, $locksHeld, 7 * 86400 );
 				if ( !$ok ) {
 					$status->fatal( 'lockmanager-fail-acquirelock', $path );
 				} else {
@@ -164,7 +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 );
@@ -297,7 +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
diff --git a/includes/filebackend/lockmanager/QuorumLockManager.php b/includes/filebackend/lockmanager/QuorumLockManager.php
index b331b540..8356d32a 100644
--- a/includes/filebackend/lockmanager/QuorumLockManager.php
+++ b/includes/filebackend/lockmanager/QuorumLockManager.php
@@ -31,81 +31,86 @@
 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)
 
-	/**
-	 * @see LockManager::doLock()
-	 * @param $paths array
-	 * @param $type int
-	 * @return Status
-	 */
 	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 => paths)
+		$pathsToLock = array(); // (bucket => type => paths)
 		// Get locks that need to be acquired (buckets => locks)...
-		foreach ( $paths as $path ) {
-			if ( isset( $this->locksHeld[$path][$type] ) ) {
-				++$this->locksHeld[$path][$type];
-			} else {
-				$bucket = $this->getBucketFromPath( $path );
-				$pathsToLock[$bucket][] = $path;
+		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
+		$lockedPaths = array(); // files locked in this attempt (type => paths)
 		// Attempt to acquire these locks...
-		foreach ( $pathsToLock as $bucket => $paths ) {
+		foreach ( $pathsToLock as $bucket => $pathsToLockByType ) {
 			// Try to acquire the locks for this bucket
-			$status->merge( $this->doLockingRequestBucket( $bucket, $paths, $type ) );
+			$status->merge( $this->doLockingRequestBucket( $bucket, $pathsToLockByType ) );
 			if ( !$status->isOK() ) {
-				$status->merge( $this->doUnlock( $lockedPaths, $type ) );
+				$status->merge( $this->doUnlockByType( $lockedPaths ) );
 				return $status;
 			}
 			// Record these locks as active
-			foreach ( $paths as $path ) {
-				$this->locksHeld[$path][$type] = 1; // locked
+			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;
+				}
 			}
-			// Keep track of what locks were made in this attempt
-			$lockedPaths = array_merge( $lockedPaths, $paths );
 		}
 
 		return $status;
 	}
 
-	/**
-	 * @see LockManager::doUnlock()
-	 * @param $paths array
-	 * @param $type int
-	 * @return Status
-	 */
-	final protected function doUnlock( array $paths, $type ) {
+	protected function doUnlockByType( array $pathsByType ) {
 		$status = Status::newGood();
 
-		$pathsToUnlock = array();
-		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][] = $path;
-				}
-				if ( !count( $this->locksHeld[$path] ) ) {
-					unset( $this->locksHeld[$path] ); // no SH or EX locks left for key
+		$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 => $paths ) {
-			$status->merge( $this->doUnlockingRequestBucket( $bucket, $paths, $type ) );
+		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;
@@ -116,25 +121,25 @@ abstract class QuorumLockManager extends LockManager {
 	 * This is all or nothing; if any key is locked then this totally fails.
 	 *
 	 * @param $bucket integer
-	 * @param array $paths List of resource keys to lock
-	 * @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
 	 * @return Status
 	 */
-	final protected function doLockingRequestBucket( $bucket, array $paths, $type ) {
+	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
+		$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, $paths, $type ) );
+			$status->merge( $this->getLocksOnServer( $lockSrv, $pathsByType ) );
 			if ( !$status->isOK() ) {
 				return $status; // vetoed; resource locked
 			}
@@ -158,21 +163,33 @@ abstract class QuorumLockManager extends LockManager {
 	 * Attempt to release locks with the peers for a bucket
 	 *
 	 * @param $bucket integer
-	 * @param array $paths List of resource keys to lock
-	 * @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
 	 * @return Status
 	 */
-	final protected function doUnlockingRequestBucket( $bucket, array $paths, $type ) {
+	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->fatal( 'lockmanager-fail-svr-release', $lockSrv );
+				$status->warning( 'lockmanager-fail-svr-release', $lockSrv );
 			// Attempt to release the lock on this peer
 			} else {
-				$status->merge( $this->freeLocksOnServer( $lockSrv, $paths, $type ) );
+				$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;
 	}
@@ -190,7 +207,8 @@ abstract class QuorumLockManager extends LockManager {
 	}
 
 	/**
-	 * Check if a lock server is up
+	 * Check if a lock server is up.
+	 * This should process cache results to reduce RTT.
 	 *
 	 * @param $lockSrv string
 	 * @return bool
@@ -198,14 +216,13 @@ abstract class QuorumLockManager extends LockManager {
 	abstract protected function isServerUp( $lockSrv );
 
 	/**
-	 * Get a connection to a lock server and acquire locks on $paths
+	 * Get a connection to a lock server and acquire locks
 	 *
 	 * @param $lockSrv string
-	 * @param $paths array
-	 * @param $type integer
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
 	 * @return Status
 	 */
-	abstract protected function getLocksOnServer( $lockSrv, array $paths, $type );
+	abstract protected function getLocksOnServer( $lockSrv, array $pathsByType );
 
 	/**
 	 * Get a connection to a lock server and release locks on $paths.
@@ -213,11 +230,10 @@ abstract class QuorumLockManager extends LockManager {
 	 * Subclasses must effectively implement this or releaseAllLocks().
 	 *
 	 * @param $lockSrv string
-	 * @param $paths array
-	 * @param $type integer
+	 * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
 	 * @return Status
 	 */
-	abstract protected function freeLocksOnServer( $lockSrv, array $paths, $type );
+	abstract protected function freeLocksOnServer( $lockSrv, array $pathsByType );
 
 	/**
 	 * Release all locks that this session is holding.
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
index edcb1d65..5faad4a6 100644
--- a/includes/filebackend/lockmanager/ScopedLock.php
+++ b/includes/filebackend/lockmanager/ScopedLock.php
@@ -36,24 +36,18 @@ class ScopedLock {
 	protected $manager;
 	/** @var Status */
 	protected $status;
-	/** @var Array List of resource paths*/
-	protected $paths;
-
-	protected $type; // integer lock type
+	/** @var Array Map of lock types to resource paths */
+	protected $pathsByType;
 
 	/**
-	 * @param $manager LockManager
-	 * @param array $paths List of storage paths
-	 * @param $type integer LockManager::LOCK_* constant
-	 * @param $status Status
+	 * @param LockManager $manager
+	 * @param array $pathsByType Map of lock types to path lists
+	 * @param Status $status
 	 */
-	protected function __construct(
-		LockManager $manager, array $paths, $type, Status $status
-	) {
+	protected function __construct( LockManager $manager, array $pathsByType, Status $status ) {
 		$this->manager = $manager;
-		$this->paths = $paths;
+		$this->pathsByType = $pathsByType;
 		$this->status = $status;
-		$this->type = $type;
 	}
 
 	/**
@@ -61,19 +55,24 @@ class ScopedLock {
 	 * Any locks are released once this object goes out of scope.
 	 * The status object is updated with any errors or warnings.
 	 *
-	 * @param $manager LockManager
-	 * @param array $paths List of storage paths
-	 * @param $type integer LockManager::LOCK_* constant
-	 * @param $status Status
+	 * $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
+		LockManager $manager, array $paths, $type, Status $status, $timeout = 0
 	) {
-		$lockStatus = $manager->lock( $paths, $type );
+		$pathsByType = is_integer( $type ) ? array( $type => $paths ) : $paths;
+		$lockStatus = $manager->lockByType( $pathsByType, $timeout );
 		$status->merge( $lockStatus );
 		if ( $lockStatus->isOK() ) {
-			return new self( $manager, $paths, $type, $status );
+			return new self( $manager, $pathsByType, $status );
 		}
 		return null;
 	}
@@ -91,9 +90,12 @@ class ScopedLock {
 		$lock = null;
 	}
 
+	/**
+	 * Release the locks when this goes out of scope
+	 */
 	function __destruct() {
 		$wasOk = $this->status->isOK();
-		$this->status->merge( $this->manager->unlock( $this->paths, $this->type ) );
+		$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 );