Merge git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache

* git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache: (41 commits)
  NFS: Add mount options to enable local caching on NFS
  NFS: Display local caching state
  NFS: Store pages from an NFS inode into a local cache
  NFS: Read pages from FS-Cache into an NFS inode
  NFS: nfs_readpage_async() needs to be accessible as a fallback for local caching
  NFS: Add read context retention for FS-Cache to call back with
  NFS: FS-Cache page management
  NFS: Add some new I/O counters for FS-Cache doing things for NFS
  NFS: Invalidate FsCache page flags when cache removed
  NFS: Use local disk inode cache
  NFS: Define and create inode-level cache objects
  NFS: Define and create superblock-level objects
  NFS: Define and create server-level objects
  NFS: Register NFS for caching and retrieve the top-level index
  NFS: Permit local filesystem caching to be enabled for NFS
  NFS: Add FS-Cache option bit and debug bit
  NFS: Add comment banners to some NFS functions
  FS-Cache: Make kAFS use FS-Cache
  CacheFiles: A cache that backs onto a mounted filesystem
  CacheFiles: Export things for CacheFiles
  ...

Documentation/filesystems/caching/operations.txt

+		       ================================
+		       ASYNCHRONOUS OPERATIONS HANDLING
+		       ================================
+
+By: David Howells <dhowells@redhat.com>
+
+Contents:
+
+ (*) Overview.
+
+ (*) Operation record initialisation.
+
+ (*) Parameters.
+
+ (*) Procedure.
+
+ (*) Asynchronous callback.
+
+
+========
+OVERVIEW
+========
+
+FS-Cache has an asynchronous operations handling facility that it uses for its
+data storage and retrieval routines.  Its operations are represented by
+fscache_operation structs, though these are usually embedded into some other
+structure.
+
+This facility is available to and expected to be be used by the cache backends,
+and FS-Cache will create operations and pass them off to the appropriate cache
+backend for completion.
+
+To make use of this facility, <linux/fscache-cache.h> should be #included.
+
+
+===============================
+OPERATION RECORD INITIALISATION
+===============================
+
+An operation is recorded in an fscache_operation struct:
+
+	struct fscache_operation {
+		union {
+			struct work_struct fast_work;
+			struct slow_work slow_work;
+		};
+		unsigned long		flags;
+		fscache_operation_processor_t processor;
+		...
+	};
+
+Someone wanting to issue an operation should allocate something with this
+struct embedded in it.  They should initialise it by calling:
+
+	void fscache_operation_init(struct fscache_operation *op,
+				    fscache_operation_release_t release);
+
+with the operation to be initialised and the release function to use.
+
+The op->flags parameter should be set to indicate the CPU time provision and
+the exclusivity (see the Parameters section).
+
+The op->fast_work, op->slow_work and op->processor flags should be set as
+appropriate for the CPU time provision (see the Parameters section).
+
+FSCACHE_OP_WAITING may be set in op->flags prior to each submission of the
+operation and waited for afterwards.
+
+
+==========
+PARAMETERS
+==========
+
+There are a number of parameters that can be set in the operation record's flag
+parameter.  There are three options for the provision of CPU time in these
+operations:
+
+ (1) The operation may be done synchronously (FSCACHE_OP_MYTHREAD).  A thread
+     may decide it wants to handle an operation itself without deferring it to
+     another thread.
+
+     This is, for example, used in read operations for calling readpages() on
+     the backing filesystem in CacheFiles.  Although readpages() does an
+     asynchronous data fetch, the determination of whether pages exist is done
+     synchronously - and the netfs does not proceed until this has been
+     determined.
+
+     If this option is to be used, FSCACHE_OP_WAITING must be set in op->flags
+     before submitting the operation, and the operating thread must wait for it
+     to be cleared before proceeding:
+
+		wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
+			    fscache_wait_bit, TASK_UNINTERRUPTIBLE);
+
+
+ (2) The operation may be fast asynchronous (FSCACHE_OP_FAST), in which case it
+     will be given to keventd to process.  Such an operation is not permitted
+     to sleep on I/O.
+
+     This is, for example, used by CacheFiles to copy data from a backing fs
+     page to a netfs page after the backing fs has read the page in.
+
+     If this option is used, op->fast_work and op->processor must be
+     initialised before submitting the operation:
+
+		INIT_WORK(&op->fast_work, do_some_work);
+
+
+ (3) The operation may be slow asynchronous (FSCACHE_OP_SLOW), in which case it
+     will be given to the slow work facility to process.  Such an operation is
+     permitted to sleep on I/O.
+
+     This is, for example, used by FS-Cache to handle background writes of
+     pages that have just been fetched from a remote server.
+
+     If this option is used, op->slow_work and op->processor must be
+     initialised before submitting the operation:
+
+		fscache_operation_init_slow(op, processor)
+
+
+Furthermore, operations may be one of two types:
+
+ (1) Exclusive (FSCACHE_OP_EXCLUSIVE).  Operations of this type may not run in
+     conjunction with any other operation on the object being operated upon.
+
+     An example of this is the attribute change operation, in which the file
+     being written to may need truncation.
+
+ (2) Shareable.  Operations of this type may be running simultaneously.  It's
+     up to the operation implementation to prevent interference between other
+     operations running at the same time.
+
+
+=========
+PROCEDURE
+=========
+
+Operations are used through the following procedure:
+
+ (1) The submitting thread must allocate the operation and initialise it
+     itself.  Normally this would be part of a more specific structure with the
+     generic op embedded within.
+
+ (2) The submitting thread must then submit the operation for processing using
+     one of the following two functions:
+
+	int fscache_submit_op(struct fscache_object *object,
+			      struct fscache_operation *op);
+
+	int fscache_submit_exclusive_op(struct fscache_object *object,
+					struct fscache_operation *op);
+
+     The first function should be used to submit non-exclusive ops and the
+     second to submit exclusive ones.  The caller must still set the
+     FSCACHE_OP_EXCLUSIVE flag.
+
+     If successful, both functions will assign the operation to the specified
+     object and return 0.  -ENOBUFS will be returned if the object specified is
+     permanently unavailable.
+
+     The operation manager will defer operations on an object that is still
+     undergoing lookup or creation.  The operation will also be deferred if an
+     operation of conflicting exclusivity is in progress on the object.
+
+     If the operation is asynchronous, the manager will retain a reference to
+     it, so the caller should put their reference to it by passing it to:
+
+	void fscache_put_operation(struct fscache_operation *op);
+
+ (3) If the submitting thread wants to do the work itself, and has marked the
+     operation with FSCACHE_OP_MYTHREAD, then it should monitor
+     FSCACHE_OP_WAITING as described above and check the state of the object if
+     necessary (the object might have died whilst the thread was waiting).
+
+     When it has finished doing its processing, it should call
+     fscache_put_operation() on it.
+
+ (4) The operation holds an effective lock upon the object, preventing other
+     exclusive ops conflicting until it is released.  The operation can be
+     enqueued for further immediate asynchronous processing by adjusting the
+     CPU time provisioning option if necessary, eg:
+
+	op->flags &= ~FSCACHE_OP_TYPE;
+	op->flags |= ~FSCACHE_OP_FAST;
+
+     and calling:
+
+	void fscache_enqueue_operation(struct fscache_operation *op)
+
+     This can be used to allow other things to have use of the worker thread
+     pools.
+
+
+=====================
+ASYNCHRONOUS CALLBACK
+=====================
+
+When used in asynchronous mode, the worker thread pool will invoke the
+processor method with a pointer to the operation.  This should then get at the
+container struct by using container_of():
+
+	static void fscache_write_op(struct fscache_operation *_op)
+	{
+		struct fscache_storage *op =
+			container_of(_op, struct fscache_storage, op);
+	...
+	}
+
+The caller holds a reference on the operation, and will invoke
+fscache_put_operation() when the processor function returns.  The processor
+function is at liberty to call fscache_enqueue_operation() or to take extra
+references.

Documentation/slow-work.txt

+		     ====================================
+		     SLOW WORK ITEM EXECUTION THREAD POOL
+		     ====================================
+
+By: David Howells <dhowells@redhat.com>
+
+The slow work item execution thread pool is a pool of threads for performing
+things that take a relatively long time, such as making mkdir calls.
+Typically, when processing something, these items will spend a lot of time
+blocking a thread on I/O, thus making that thread unavailable for doing other
+work.
+
+The standard workqueue model is unsuitable for this class of work item as that
+limits the owner to a single thread or a single thread per CPU.  For some
+tasks, however, more threads - or fewer - are required.
+
+There is just one pool per system.  It contains no threads unless something
+wants to use it - and that something must register its interest first.  When
+the pool is active, the number of threads it contains is dynamic, varying
+between a maximum and minimum setting, depending on the load.
+
+
+====================
+CLASSES OF WORK ITEM
+====================
+
+This pool support two classes of work items:
+
+ (*) Slow work items.
+
+ (*) Very slow work items.
+
+The former are expected to finish much quicker than the latter.
+
+An operation of the very slow class may do a batch combination of several
+lookups, mkdirs, and a create for instance.
+
+An operation of the ordinarily slow class may, for example, write stuff or
+expand files, provided the time taken to do so isn't too long.
+
+Operations of both types may sleep during execution, thus tying up the thread
+loaned to it.
+
+
+THREAD-TO-CLASS ALLOCATION
+--------------------------
+
+Not all the threads in the pool are available to work on very slow work items.
+The number will be between one and one fewer than the number of active threads.
+This is configurable (see the "Pool Configuration" section).
+
+All the threads are available to work on ordinarily slow work items, but a
+percentage of the threads will prefer to work on very slow work items.
+
+The configuration ensures that at least one thread will be available to work on
+very slow work items, and at least one thread will be available that won't work
+on very slow work items at all.
+
+
+=====================
+USING SLOW WORK ITEMS
+=====================
+
+Firstly, a module or subsystem wanting to make use of slow work items must
+register its interest:
+
+	 int ret = slow_work_register_user();
+
+This will return 0 if successful, or a -ve error upon failure.
+
+
+Slow work items may then be set up by:
+
+ (1) Declaring a slow_work struct type variable:
+
+	#include <linux/slow-work.h>
+
+	struct slow_work myitem;
+
+ (2) Declaring the operations to be used for this item:
+
+	struct slow_work_ops myitem_ops = {
+		.get_ref = myitem_get_ref,
+		.put_ref = myitem_put_ref,
+		.execute = myitem_execute,
+	};
+
+     [*] For a description of the ops, see section "Item Operations".
+
+ (3) Initialising the item:
+
+	slow_work_init(&myitem, &myitem_ops);
+
+     or:
+
+	vslow_work_init(&myitem, &myitem_ops);
+
+     depending on its class.
+
+A suitably set up work item can then be enqueued for processing:
+
+	int ret = slow_work_enqueue(&myitem);
+
+This will return a -ve error if the thread pool is unable to gain a reference
+on the item, 0 otherwise.
+
+
+The items are reference counted, so there ought to be no need for a flush
+operation.  When all a module's slow work items have been processed, and the
+module has no further interest in the facility, it should unregister its
+interest:
+
+	slow_work_unregister_user();
+
+
+===============
+ITEM OPERATIONS
+===============
+
+Each work item requires a table of operations of type struct slow_work_ops.
+All members are required:
+
+ (*) Get a reference on an item:
+
+	int (*get_ref)(struct slow_work *work);
+
+     This allows the thread pool to attempt to pin an item by getting a
+     reference on it.  This function should return 0 if the reference was
+     granted, or a -ve error otherwise.  If an error is returned,
+     slow_work_enqueue() will fail.
+
+     The reference is held whilst the item is queued and whilst it is being
+     executed.  The item may then be requeued with the same reference held, or
+     the reference will be released.
+
+ (*) Release a reference on an item:
+
+	void (*put_ref)(struct slow_work *work);
+
+     This allows the thread pool to unpin an item by releasing the reference on
+     it.  The thread pool will not touch the item again once this has been
+     called.
+
+ (*) Execute an item:
+
+	void (*execute)(struct slow_work *work);
+
+     This should perform the work required of the item.  It may sleep, it may
+     perform disk I/O and it may wait for locks.
+
+
+==================
+POOL CONFIGURATION
+==================
+
+The slow-work thread pool has a number of configurables:
+
+ (*) /proc/sys/kernel/slow-work/min-threads
+
+     The minimum number of threads that should be in the pool whilst it is in
+     use.  This may be anywhere between 2 and max-threads.
+
+ (*) /proc/sys/kernel/slow-work/max-threads
+
+     The maximum number of threads that should in the pool.  This may be
+     anywhere between min-threads and 255 or NR_CPUS * 2, whichever is greater.
+
+ (*) /proc/sys/kernel/slow-work/vslow-percentage
+
+     The percentage of active threads in the pool that may be used to execute
+     very slow work items.  This may be between 1 and 99.  The resultant number
+     is bounded to between 1 and one fewer than the number of active threads.
+     This ensures there is always at least one thread that can process very
+     slow work items, and always at least one thread that won't.

fs/Kconfig

@@ -66,6 +66,13 @@ config GENERIC_ACL
 	bool
 	select FS_POSIX_ACL
 
+menu "Caches"
+
+source "fs/fscache/Kconfig"
+source "fs/cachefiles/Kconfig"
+
+endmenu
+
 if BLOCK
 menu "CD-ROM/DVD Filesystems"
 

fs/Makefile

@@ -63,6 +63,7 @@ obj-$(CONFIG_PROFILING)		+= dcookies.o
 obj-$(CONFIG_DLM)		+= dlm/
  
 # Do not add any filesystems before this line
+obj-$(CONFIG_FSCACHE)		+= fscache/
 obj-$(CONFIG_REISERFS_FS)	+= reiserfs/
 obj-$(CONFIG_EXT3_FS)		+= ext3/ # Before ext2 so root fs can be ext3
 obj-$(CONFIG_EXT2_FS)		+= ext2/
@@ -116,6 +117,7 @@ obj-$(CONFIG_AFS_FS)		+= afs/
 obj-$(CONFIG_BEFS_FS)		+= befs/
 obj-$(CONFIG_HOSTFS)		+= hostfs/
 obj-$(CONFIG_HPPFS)		+= hppfs/
+obj-$(CONFIG_CACHEFILES)	+= cachefiles/
 obj-$(CONFIG_DEBUG_FS)		+= debugfs/
 obj-$(CONFIG_OCFS2_FS)		+= ocfs2/
 obj-$(CONFIG_BTRFS_FS)		+= btrfs/

fs/afs/Kconfig

@@ -19,3 +19,11 @@ config AFS_DEBUG
 	  See <file:Documentation/filesystems/afs.txt> for more information.
 
 	  If unsure, say N.
+
+config AFS_FSCACHE
+	bool "Provide AFS client caching support (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+	depends on AFS_FS=m && FSCACHE || AFS_FS=y && FSCACHE=y
+	help
+	  Say Y here if you want AFS data to be cached locally on disk through
+	  the generic filesystem cache manager

fs/afs/Makefile

@@ -2,7 +2,10 @@
 # Makefile for Red Hat Linux AFS client.
 #
 
+afs-cache-$(CONFIG_AFS_FSCACHE) := cache.o
+
 kafs-objs := \
+	$(afs-cache-y) \
 	callback.o \
 	cell.o \
 	cmservice.o \

fs/afs/cache.h

 /* AFS local cache management interface
  *
- * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
@@ -9,15 +9,4 @@
  * 2 of the License, or (at your option) any later version.
  */
 
-#ifndef AFS_CACHE_H
-#define AFS_CACHE_H
-
-#undef AFS_CACHING_SUPPORT
-
-#include <linux/mm.h>
-#ifdef AFS_CACHING_SUPPORT
-#include <linux/cachefs.h>
-#endif
-#include "types.h"
-
-#endif /* AFS_CACHE_H */
+#include <linux/fscache.h>

fs/afs/cell.c

@@ -147,12 +147,11 @@ struct afs_cell *afs_cell_create(const char *name, char *vllist)
 	if (ret < 0)
 		goto error;
 
-#ifdef AFS_CACHING_SUPPORT
-	/* put it up for caching */
-	cachefs_acquire_cookie(afs_cache_netfs.primary_index,
-			       &afs_vlocation_cache_index_def,
-			       cell,
-			       &cell->cache);
+#ifdef CONFIG_AFS_FSCACHE
+	/* put it up for caching (this never returns an error) */
+	cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
+					     &afs_cell_cache_index_def,
+					     cell);
 #endif
 
 	/* add to the cell lists */
@@ -362,10 +361,9 @@ static void afs_cell_destroy(struct afs_cell *cell)
 	list_del_init(&cell->proc_link);
 	up_write(&afs_proc_cells_sem);
 
-#ifdef AFS_CACHING_SUPPORT
-	cachefs_relinquish_cookie(cell->cache, 0);
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_relinquish_cookie(cell->cache, 0);
 #endif
-
 	key_put(cell->anonymous_key);
 	kfree(cell);
 

fs/afs/file.c

@@ -23,6 +23,9 @@ static void afs_invalidatepage(struct page *page, unsigned long offset);
 static int afs_releasepage(struct page *page, gfp_t gfp_flags);
 static int afs_launder_page(struct page *page);
 
+static int afs_readpages(struct file *filp, struct address_space *mapping,
+			 struct list_head *pages, unsigned nr_pages);
+
 const struct file_operations afs_file_operations = {
 	.open		= afs_open,
 	.release	= afs_release,
@@ -46,6 +49,7 @@ const struct inode_operations afs_file_inode_operations = {
 
 const struct address_space_operations afs_fs_aops = {
 	.readpage	= afs_readpage,
+	.readpages	= afs_readpages,
 	.set_page_dirty	= afs_set_page_dirty,
 	.launder_page	= afs_launder_page,
 	.releasepage	= afs_releasepage,
@@ -101,37 +105,18 @@ int afs_release(struct inode *inode, struct file *file)
 /*
  * deal with notification that a page was read from the cache
  */
-#ifdef AFS_CACHING_SUPPORT
-static void afs_readpage_read_complete(void *cookie_data,
-				       struct page *page,
+static void afs_file_readpage_read_complete(struct page *page,
 					    void *data,
 					    int error)
 {
-	_enter("%p,%p,%p,%d", cookie_data, page, data, error);
+	_enter("%p,%p,%d", page, data, error);
 
-	if (error)
-		SetPageError(page);
-	else
+	/* if the read completes with an error, we just unlock the page and let
+	 * the VM reissue the readpage */
+	if (!error)
 		SetPageUptodate(page);
 	unlock_page(page);
-
-}
-#endif
-
-/*
- * deal with notification that a page was written to the cache
- */
-#ifdef AFS_CACHING_SUPPORT
-static void afs_readpage_write_complete(void *cookie_data,
-					struct page *page,
-					void *data,
-					int error)
-{
-	_enter("%p,%p,%p,%d", cookie_data, page, data, error);
-
-	unlock_page(page);
 }
-#endif
 
 /*
  * AFS read page from file, directory or symlink
@@ -161,9 +146,9 @@ static int afs_readpage(struct file *file, struct page *page)
 	if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 		goto error;
 
-#ifdef AFS_CACHING_SUPPORT
 	/* is it cached? */
-	ret = cachefs_read_or_alloc_page(vnode->cache,
+#ifdef CONFIG_AFS_FSCACHE
+	ret = fscache_read_or_alloc_page(vnode->cache,
 					 page,
 					 afs_file_readpage_read_complete,
 					 NULL,
@@ -171,20 +156,21 @@ static int afs_readpage(struct file *file, struct page *page)
 #else
 	ret = -ENOBUFS;
 #endif
-
 	switch (ret) {
-		/* read BIO submitted and wb-journal entry found */
-	case 1:
-		BUG(); // TODO - handle wb-journal match
-
 		/* read BIO submitted (page in cache) */
 	case 0:
 		break;
 
-		/* no page available in cache */
-	case -ENOBUFS:
+		/* page not yet cached */
 	case -ENODATA:
+		_debug("cache said ENODATA");
+		goto go_on;
+
+		/* page will not be cached */
+	case -ENOBUFS:
+		_debug("cache said ENOBUFS");
 	default:
+	go_on:
 		offset = page->index << PAGE_CACHE_SHIFT;
 		len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE);
 
@@ -198,27 +184,25 @@ static int afs_readpage(struct file *file, struct page *page)
 				set_bit(AFS_VNODE_DELETED, &vnode->flags);
 				ret = -ESTALE;
 			}
-#ifdef AFS_CACHING_SUPPORT
-			cachefs_uncache_page(vnode->cache, page);
+
+#ifdef CONFIG_AFS_FSCACHE
+			fscache_uncache_page(vnode->cache, page);
 #endif
+			BUG_ON(PageFsCache(page));
 			goto error;
 		}
 
 		SetPageUptodate(page);
 
-#ifdef AFS_CACHING_SUPPORT
-		if (cachefs_write_page(vnode->cache,
-				       page,
-				       afs_file_readpage_write_complete,
-				       NULL,
-				       GFP_KERNEL) != 0
-		    ) {
-			cachefs_uncache_page(vnode->cache, page);
-			unlock_page(page);
+		/* send the page to the cache */
+#ifdef CONFIG_AFS_FSCACHE
+		if (PageFsCache(page) &&
+		    fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
+			fscache_uncache_page(vnode->cache, page);
+			BUG_ON(PageFsCache(page));
 		}
-#else
-		unlock_page(page);
 #endif
+		unlock_page(page);
 	}
 
 	_leave(" = 0");
@@ -232,34 +216,59 @@ static int afs_readpage(struct file *file, struct page *page)
 }
 
 /*
- * invalidate part or all of a page
+ * read a set of pages
  */
-static void afs_invalidatepage(struct page *page, unsigned long offset)
+static int afs_readpages(struct file *file, struct address_space *mapping,
+			 struct list_head *pages, unsigned nr_pages)
 {
-	int ret = 1;
+	struct afs_vnode *vnode;
+	int ret = 0;
 
-	_enter("{%lu},%lu", page->index, offset);
+	_enter(",{%lu},,%d", mapping->host->i_ino, nr_pages);
 
-	BUG_ON(!PageLocked(page));
+	vnode = AFS_FS_I(mapping->host);
+	if (vnode->flags & AFS_VNODE_DELETED) {
+		_leave(" = -ESTALE");
+		return -ESTALE;
+	}
 
-	if (PagePrivate(page)) {
-		/* We release buffers only if the entire page is being
-		 * invalidated.
-		 * The get_block cached value has been unconditionally
-		 * invalidated, so real IO is not possible anymore.
-		 */
-		if (offset == 0) {
-			BUG_ON(!PageLocked(page));
+	/* attempt to read as many of the pages as possible */
+#ifdef CONFIG_AFS_FSCACHE
+	ret = fscache_read_or_alloc_pages(vnode->cache,
+					  mapping,
+					  pages,
+					  &nr_pages,
+					  afs_file_readpage_read_complete,
+					  NULL,
+					  mapping_gfp_mask(mapping));
+#else
+	ret = -ENOBUFS;
+#endif
 
-			ret = 0;
-			if (!PageWriteback(page))
-				ret = page->mapping->a_ops->releasepage(page,
-									0);
-			/* possibly should BUG_ON(!ret); - neilb */
-		}
-	}
+	switch (ret) {
+		/* all pages are being read from the cache */
+	case 0:
+		BUG_ON(!list_empty(pages));
+		BUG_ON(nr_pages != 0);
+		_leave(" = 0 [reading all]");
+		return 0;
+
+		/* there were pages that couldn't be read from the cache */
+	case -ENODATA:
+	case -ENOBUFS:
+		break;
 
+		/* other error */
+	default:
 		_leave(" = %d", ret);
+		return ret;
+	}
+
+	/* load the missing pages from the network */
+	ret = read_cache_pages(mapping, pages, (void *) afs_readpage, file);
+
+	_leave(" = %d [netting]", ret);
+	return ret;
 }
 
 /*
@@ -273,25 +282,82 @@ static int afs_launder_page(struct page *page)
 }
 
 /*
- * release a page and cleanup its private data
+ * invalidate part or all of a page
+ * - release a page and clean up its private data if offset is 0 (indicating
+ *   the entire page)
+ */
+static void afs_invalidatepage(struct page *page, unsigned long offset)
+{
+	struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
+
+	_enter("{%lu},%lu", page->index, offset);
+
+	BUG_ON(!PageLocked(page));
+
+	/* we clean up only if the entire page is being invalidated */
+	if (offset == 0) {
+#ifdef CONFIG_AFS_FSCACHE
+		if (PageFsCache(page)) {
+			struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
+			fscache_wait_on_page_write(vnode->cache, page);
+			fscache_uncache_page(vnode->cache, page);
+			ClearPageFsCache(page);
+		}
+#endif
+
+		if (PagePrivate(page)) {
+			if (wb && !PageWriteback(page)) {
+				set_page_private(page, 0);
+				afs_put_writeback(wb);
+			}
+
+			if (!page_private(page))
+				ClearPagePrivate(page);
+		}
+	}
+
+	_leave("");
+}
+
+/*
+ * release a page and clean up its private state if it's not busy
+ * - return true if the page can now be released, false if not
  */
 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 {
+	struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
-	struct afs_writeback *wb;
 
 	_enter("{{%x:%u}[%lu],%lx},%x",
 	       vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
 	       gfp_flags);
 
+	/* deny if page is being written to the cache and the caller hasn't
+	 * elected to wait */
+#ifdef CONFIG_AFS_FSCACHE
+	if (PageFsCache(page)) {
+		if (fscache_check_page_write(vnode->cache, page)) {
+			if (!(gfp_flags & __GFP_WAIT)) {
+				_leave(" = F [cache busy]");
+				return 0;
+			}
+			fscache_wait_on_page_write(vnode->cache, page);
+		}
+
+		fscache_uncache_page(vnode->cache, page);
+		ClearPageFsCache(page);
+	}
+#endif
+
 	if (PagePrivate(page)) {
-		wb = (struct afs_writeback *) page_private(page);
-		ASSERT(wb != NULL);
+		if (wb) {
 			set_page_private(page, 0);
-		ClearPagePrivate(page);
 			afs_put_writeback(wb);
 		}
+		ClearPagePrivate(page);
+	}
 
-	_leave(" = 0");
-	return 0;
+	/* indicate that the page can be released */
+	_leave(" = T");
+	return 1;
 }

fs/afs/inode.c

@@ -61,6 +61,11 @@ static int afs_inode_map_status(struct afs_vnode *vnode, struct key *key)
 		return -EBADMSG;
 	}
 
+#ifdef CONFIG_AFS_FSCACHE
+	if (vnode->status.size != inode->i_size)
+		fscache_attr_changed(vnode->cache);
+#endif
+
 	inode->i_nlink		= vnode->status.nlink;
 	inode->i_uid		= vnode->status.owner;
 	inode->i_gid		= 0;
@@ -149,15 +154,6 @@ struct inode *afs_iget(struct super_block *sb, struct key *key,
 		return inode;
 	}
 
-#ifdef AFS_CACHING_SUPPORT
-	/* set up caching before reading the status, as fetch-status reads the
-	 * first page of symlinks to see if they're really mntpts */
-	cachefs_acquire_cookie(vnode->volume->cache,
-			       NULL,
-			       vnode,
-			       &vnode->cache);
-#endif
-
 	if (!status) {
 		/* it's a remotely extant inode */
 		set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
@@ -183,6 +179,15 @@ struct inode *afs_iget(struct super_block *sb, struct key *key,
 		}
 	}
 
+	/* set up caching before mapping the status, as map-status reads the
+	 * first page of symlinks to see if they're really mountpoints */
+	inode->i_size = vnode->status.size;
+#ifdef CONFIG_AFS_FSCACHE
+	vnode->cache = fscache_acquire_cookie(vnode->volume->cache,
+					      &afs_vnode_cache_index_def,
+					      vnode);
+#endif
+
 	ret = afs_inode_map_status(vnode, key);
 	if (ret < 0)
 		goto bad_inode;
@@ -196,6 +201,10 @@ struct inode *afs_iget(struct super_block *sb, struct key *key,
 
 	/* failure */
 bad_inode:
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_relinquish_cookie(vnode->cache, 0);
+	vnode->cache = NULL;
+#endif
 	iget_failed(inode);
 	_leave(" = %d [bad]", ret);
 	return ERR_PTR(ret);
@@ -340,8 +349,8 @@ void afs_clear_inode(struct inode *inode)
 	ASSERT(list_empty(&vnode->writebacks));
 	ASSERT(!vnode->cb_promised);
 
-#ifdef AFS_CACHING_SUPPORT
-	cachefs_relinquish_cookie(vnode->cache, 0);
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_relinquish_cookie(vnode->cache, 0);
 	vnode->cache = NULL;
 #endif
 

fs/afs/internal.h

@@ -21,6 +21,7 @@
 
 #include "afs.h"
 #include "afs_vl.h"
+#include "cache.h"
 
 #define AFS_CELL_MAX_ADDRS 15
 
@@ -193,8 +194,8 @@ struct afs_cell {
 	struct key		*anonymous_key;	/* anonymous user key for this cell */
 	struct list_head	proc_link;	/* /proc cell list link */
 	struct proc_dir_entry	*proc_dir;	/* /proc dir for this cell */
-#ifdef AFS_CACHING_SUPPORT
-	struct cachefs_cookie	*cache;		/* caching cookie */
+#ifdef CONFIG_AFS_FSCACHE
+	struct fscache_cookie	*cache;		/* caching cookie */
 #endif
 
 	/* server record management */
@@ -249,8 +250,8 @@ struct afs_vlocation {
 	struct list_head	grave;		/* link in master graveyard list */
 	struct list_head	update;		/* link in master update list */
 	struct afs_cell		*cell;		/* cell to which volume belongs */
-#ifdef AFS_CACHING_SUPPORT
-	struct cachefs_cookie	*cache;		/* caching cookie */
+#ifdef CONFIG_AFS_FSCACHE
+	struct fscache_cookie	*cache;		/* caching cookie */
 #endif
 	struct afs_cache_vlocation vldb;	/* volume information DB record */
 	struct afs_volume	*vols[3];	/* volume access record pointer (index by type) */
@@ -302,8 +303,8 @@ struct afs_volume {
 	atomic_t		usage;
 	struct afs_cell		*cell;		/* cell to which belongs (unrefd ptr) */
 	struct afs_vlocation	*vlocation;	/* volume location */
-#ifdef AFS_CACHING_SUPPORT
-	struct cachefs_cookie	*cache;		/* caching cookie */
+#ifdef CONFIG_AFS_FSCACHE
+	struct fscache_cookie	*cache;		/* caching cookie */
 #endif
 	afs_volid_t		vid;		/* volume ID */
 	afs_voltype_t		type;		/* type of volume */
@@ -333,8 +334,8 @@ struct afs_vnode {
 	struct afs_server	*server;	/* server currently supplying this file */
 	struct afs_fid		fid;		/* the file identifier for this inode */
 	struct afs_file_status	status;		/* AFS status info for this file */
-#ifdef AFS_CACHING_SUPPORT
-	struct cachefs_cookie	*cache;		/* caching cookie */
+#ifdef CONFIG_AFS_FSCACHE
+	struct fscache_cookie	*cache;		/* caching cookie */
 #endif
 	struct afs_permits	*permits;	/* cache of permits so far obtained */
 	struct mutex		permits_lock;	/* lock for altering permits list */
@@ -427,6 +428,22 @@ struct afs_uuid {
 };
 
 /*****************************************************************************/
+/*
+ * cache.c
+ */
+#ifdef CONFIG_AFS_FSCACHE
+extern struct fscache_netfs afs_cache_netfs;
+extern struct fscache_cookie_def afs_cell_cache_index_def;
+extern struct fscache_cookie_def afs_vlocation_cache_index_def;
+extern struct fscache_cookie_def afs_volume_cache_index_def;
+extern struct fscache_cookie_def afs_vnode_cache_index_def;
+#else
+#define afs_cell_cache_index_def	(*(struct fscache_cookie_def *) NULL)
+#define afs_vlocation_cache_index_def	(*(struct fscache_cookie_def *) NULL)
+#define afs_volume_cache_index_def	(*(struct fscache_cookie_def *) NULL)
+#define afs_vnode_cache_index_def	(*(struct fscache_cookie_def *) NULL)
+#endif
+
 /*
  * callback.c
  */
@@ -446,9 +463,6 @@ extern void afs_callback_update_kill(void);
  */
 extern struct rw_semaphore afs_proc_cells_sem;
 extern struct list_head afs_proc_cells;
-#ifdef AFS_CACHING_SUPPORT
-extern struct cachefs_index_def afs_cache_cell_index_def;
-#endif
 
 #define afs_get_cell(C) do { atomic_inc(&(C)->usage); } while(0)
 extern int afs_cell_init(char *);
@@ -554,9 +568,6 @@ extern void afs_clear_inode(struct inode *);
  * main.c
  */
 extern struct afs_uuid afs_uuid;
-#ifdef AFS_CACHING_SUPPORT
-extern struct cachefs_netfs afs_cache_netfs;
-#endif
 
 /*
  * misc.c
@@ -637,10 +648,6 @@ extern int afs_get_MAC_address(u8 *, size_t);
 /*
  * vlclient.c
  */
-#ifdef AFS_CACHING_SUPPORT
-extern struct cachefs_index_def afs_vlocation_cache_index_def;
-#endif
-
 extern int afs_vl_get_entry_by_name(struct in_addr *, struct key *,
 				    const char *, struct afs_cache_vlocation *,
 				    const struct afs_wait_mode *);
@@ -664,12 +671,6 @@ extern void afs_vlocation_purge(void);
 /*
  * vnode.c
  */
-#ifdef AFS_CACHING_SUPPORT
-extern struct cachefs_index_def afs_vnode_cache_index_def;
-#endif
-
-extern struct afs_timer_ops afs_vnode_cb_timed_out_ops;
-
 static inline struct afs_vnode *AFS_FS_I(struct inode *inode)
 {
 	return container_of(inode, struct afs_vnode, vfs_inode);
@@ -711,10 +712,6 @@ extern int afs_vnode_release_lock(struct afs_vnode *, struct key *);
 /*
  * volume.c
  */
-#ifdef AFS_CACHING_SUPPORT
-extern struct cachefs_index_def afs_volume_cache_index_def;
-#endif
-
 #define afs_get_volume(V) do { atomic_inc(&(V)->usage); } while(0)
 
 extern void afs_put_volume(struct afs_volume *);

fs/afs/main.c

 /* AFS client file system
  *
- * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2002,5 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
@@ -29,18 +29,6 @@ static char *rootcell;
 module_param(rootcell, charp, 0);
 MODULE_PARM_DESC(rootcell, "root AFS cell name and VL server IP addr list");
 
-#ifdef AFS_CACHING_SUPPORT
-static struct cachefs_netfs_operations afs_cache_ops = {
-	.get_page_cookie	= afs_cache_get_page_cookie,
-};
-
-struct cachefs_netfs afs_cache_netfs = {
-	.name			= "afs",
-	.version		= 0,
-	.ops			= &afs_cache_ops,
-};
-#endif
-
 struct afs_uuid afs_uuid;
 
 /*
@@ -104,10 +92,9 @@ static int __init afs_init(void)
 	if (ret < 0)
 		return ret;
 
-#ifdef AFS_CACHING_SUPPORT
+#ifdef CONFIG_AFS_FSCACHE
 	/* we want to be able to cache */
-	ret = cachefs_register_netfs(&afs_cache_netfs,
-				     &afs_cache_cell_index_def);
+	ret = fscache_register_netfs(&afs_cache_netfs);
 	if (ret < 0)
 		goto error_cache;
 #endif
@@ -142,8 +129,8 @@ static int __init afs_init(void)
 error_open_socket:
 error_vl_update_init:
 error_cell_init:
-#ifdef AFS_CACHING_SUPPORT
-	cachefs_unregister_netfs(&afs_cache_netfs);
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_unregister_netfs(&afs_cache_netfs);
 error_cache:
 #endif
 	afs_callback_update_kill();
@@ -175,8 +162,8 @@ static void __exit afs_exit(void)
 	afs_vlocation_purge();
 	flush_scheduled_work();
 	afs_cell_purge();
-#ifdef AFS_CACHING_SUPPORT
-	cachefs_unregister_netfs(&afs_cache_netfs);
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_unregister_netfs(&afs_cache_netfs);
 #endif
 	afs_proc_cleanup();
 	rcu_barrier();

fs/afs/mntpt.c

@@ -173,9 +173,9 @@ static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
 	if (PageError(page))
 		goto error;
 
-	buf = kmap(page);
+	buf = kmap_atomic(page, KM_USER0);
 	memcpy(devname, buf, size);
-	kunmap(page);
+	kunmap_atomic(buf, KM_USER0);
 	page_cache_release(page);
 	page = NULL;
 

fs/afs/vlocation.c

@@ -281,9 +281,8 @@ static void afs_vlocation_apply_update(struct afs_vlocation *vl,
 
 	vl->vldb = *vldb;
 
-#ifdef AFS_CACHING_SUPPORT
-	/* update volume entry in local cache */
-	cachefs_update_cookie(vl->cache);
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_update_cookie(vl->cache);
 #endif
 }
 
@@ -304,11 +303,9 @@ static int afs_vlocation_fill_in_record(struct afs_vlocation *vl,
 	memset(&vldb, 0, sizeof(vldb));
 
 	/* see if we have an in-cache copy (will set vl->valid if there is) */
-#ifdef AFS_CACHING_SUPPORT
-	cachefs_acquire_cookie(cell->cache,
-			       &afs_volume_cache_index_def,
-			       vlocation,
-			       &vl->cache);
+#ifdef CONFIG_AFS_FSCACHE
+	vl->cache = fscache_acquire_cookie(vl->cell->cache,
+					   &afs_vlocation_cache_index_def, vl);
 #endif
 
 	if (vl->valid) {
@@ -420,6 +417,11 @@ struct afs_vlocation *afs_vlocation_lookup(struct afs_cell *cell,
 	spin_unlock(&vl->lock);
 	wake_up(&vl->waitq);
 
+	/* update volume entry in local cache */
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_update_cookie(vl->cache);
+#endif
+
 	/* schedule for regular updates */
 	afs_vlocation_queue_for_updates(vl);
 	goto success;
@@ -465,7 +467,7 @@ struct afs_vlocation *afs_vlocation_lookup(struct afs_cell *cell,
 	spin_unlock(&vl->lock);
 
 success:
-	_leave(" = %p",vl);
+	_leave(" = %p", vl);
 	return vl;
 
 error_abandon:
@@ -523,10 +525,9 @@ static void afs_vlocation_destroy(struct afs_vlocation *vl)
 {
 	_enter("%p", vl);
 
-#ifdef AFS_CACHING_SUPPORT
-	cachefs_relinquish_cookie(vl->cache, 0);
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_relinquish_cookie(vl->cache, 0);
 #endif
-
 	afs_put_cell(vl->cell);
 	kfree(vl);
 }

fs/afs/volume.c

@@ -124,13 +124,11 @@ struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
 	}
 
 	/* attach the cache and volume location */
-#ifdef AFS_CACHING_SUPPORT
-	cachefs_acquire_cookie(vlocation->cache,
-			       &afs_vnode_cache_index_def,
-			       volume,
-			       &volume->cache);
+#ifdef CONFIG_AFS_FSCACHE
+	volume->cache = fscache_acquire_cookie(vlocation->cache,
+					       &afs_volume_cache_index_def,
+					       volume);
 #endif
-
 	afs_get_vlocation(vlocation);
 	volume->vlocation = vlocation;
 
@@ -194,8 +192,8 @@ void afs_put_volume(struct afs_volume *volume)
 	up_write(&vlocation->cell->vl_sem);
 
 	/* finish cleaning up the volume */
-#ifdef AFS_CACHING_SUPPORT
-	cachefs_relinquish_cookie(volume->cache, 0);
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_relinquish_cookie(volume->cache, 0);
 #endif
 	afs_put_vlocation(vlocation);
 

fs/afs/write.c

@@ -780,3 +780,24 @@ int afs_fsync(struct file *file, struct dentry *dentry, int datasync)
 	_leave(" = %d", ret);
 	return ret;
 }
+
+/*
+ * notification that a previously read-only page is about to become writable
+ * - if it returns an error, the caller will deliver a bus error signal
+ */
+int afs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+{
+	struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host);
+
+	_enter("{{%x:%u}},{%lx}",
+	       vnode->fid.vid, vnode->fid.vnode, page->index);
+
+	/* wait for the page to be written to the cache before we allow it to
+	 * be modified */
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_wait_on_page_write(vnode->cache, page);
+#endif
+
+	_leave(" = 0");
+	return 0;
+}

fs/cachefiles/Kconfig

+
+config CACHEFILES
+	tristate "Filesystem caching on files"
+	depends on FSCACHE && BLOCK
+	help
+	  This permits use of a mounted filesystem as a cache for other
+	  filesystems - primarily networking filesystems - thus allowing fast
+	  local disk to enhance the speed of slower devices.
+
+	  See Documentation/filesystems/caching/cachefiles.txt for more
+	  information.
+
+config CACHEFILES_DEBUG
+	bool "Debug CacheFiles"
+	depends on CACHEFILES
+	help
+	  This permits debugging to be dynamically enabled in the filesystem
+	  caching on files module.  If this is set, the debugging output may be
+	  enabled by setting bits in /sys/modules/cachefiles/parameter/debug or
+	  by including a debugging specifier in /etc/cachefilesd.conf.
+
+config CACHEFILES_HISTOGRAM
+	bool "Gather latency information on CacheFiles"
+	depends on CACHEFILES && PROC_FS
+	help
+
+	  This option causes latency information to be gathered on CacheFiles
+	  operation and exported through file:
+
+		/proc/fs/cachefiles/histogram
+
+	  The generation of this histogram adds a certain amount of overhead to
+	  execution as there are a number of points at which data is gathered,
+	  and on a multi-CPU system these may be on cachelines that keep
+	  bouncing between CPUs.  On the other hand, the histogram may be
+	  useful for debugging purposes.  Saying 'N' here is recommended.
+
+	  See Documentation/filesystems/caching/cachefiles.txt for more
+	  information.

fs/cachefiles/Makefile

+#
+# Makefile for caching in a mounted filesystem
+#
+
+cachefiles-y := \
+	bind.o \
+	daemon.o \
+	interface.o \
+	key.o \
+	main.o \
+	namei.o \
+	rdwr.o \
+	security.o \
+	xattr.o
+
+cachefiles-$(CONFIG_CACHEFILES_HISTOGRAM) += proc.o
+
+obj-$(CONFIG_CACHEFILES) := cachefiles.o

fs/cachefiles/bind.c

+/* Bind and unbind a cache from the filesystem backing it
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/completion.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/statfs.h>
+#include <linux/ctype.h>
+#include "internal.h"
+
+static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);
+
+/*
+ * bind a directory as a cache
+ */
+int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
+{
+	_enter("{%u,%u,%u,%u,%u,%u},%s",
+	       cache->frun_percent,
+	       cache->fcull_percent,
+	       cache->fstop_percent,
+	       cache->brun_percent,
+	       cache->bcull_percent,
+	       cache->bstop_percent,
+	       args);
+
+	/* start by checking things over */
+	ASSERT(cache->fstop_percent >= 0 &&
+	       cache->fstop_percent < cache->fcull_percent &&
+	       cache->fcull_percent < cache->frun_percent &&
+	       cache->frun_percent  < 100);
+
+	ASSERT(cache->bstop_percent >= 0 &&
+	       cache->bstop_percent < cache->bcull_percent &&
+	       cache->bcull_percent < cache->brun_percent &&
+	       cache->brun_percent  < 100);
+
+	if (*args) {
+		kerror("'bind' command doesn't take an argument");
+		return -EINVAL;
+	}
+
+	if (!cache->rootdirname) {
+		kerror("No cache directory specified");
+		return -EINVAL;
+	}
+
+	/* don't permit already bound caches to be re-bound */
+	if (test_bit(CACHEFILES_READY, &cache->flags)) {
+		kerror("Cache already bound");
+		return -EBUSY;
+	}
+
+	/* make sure we have copies of the tag and dirname strings */
+	if (!cache->tag) {
+		/* the tag string is released by the fops->release()
+		 * function, so we don't release it on error here */
+		cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
+		if (!cache->tag)
+			return -ENOMEM;
+	}
+
+	/* add the cache */
+	return cachefiles_daemon_add_cache(cache);
+}
+
+/*
+ * add a cache
+ */
+static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
+{
+	struct cachefiles_object *fsdef;
+	struct nameidata nd;
+	struct kstatfs stats;
+	struct dentry *graveyard, *cachedir, *root;
+	const struct cred *saved_cred;
+	int ret;
+
+	_enter("");
+
+	/* we want to work under the module's security ID */
+	ret = cachefiles_get_security_ID(cache);
+	if (ret < 0)
+		return ret;
+
+	cachefiles_begin_secure(cache, &saved_cred);
+
+	/* allocate the root index object */
+	ret = -ENOMEM;
+
+	fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
+	if (!fsdef)
+		goto error_root_object;
+
+	ASSERTCMP(fsdef->backer, ==, NULL);
+
+	atomic_set(&fsdef->usage, 1);
+	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;
+
+	_debug("- fsdef %p", fsdef);
+
+	/* look up the directory at the root of the cache */
+	memset(&nd, 0, sizeof(nd));
+
+	ret = path_lookup(cache->rootdirname, LOOKUP_DIRECTORY, &nd);
+	if (ret < 0)
+		goto error_open_root;
+
+	cache->mnt = mntget(nd.path.mnt);
+	root = dget(nd.path.dentry);
+	path_put(&nd.path);
+
+	/* check parameters */
+	ret = -EOPNOTSUPP;
+	if (!root->d_inode ||
+	    !root->d_inode->i_op ||
+	    !root->d_inode->i_op->lookup ||
+	    !root->d_inode->i_op->mkdir ||
+	    !root->d_inode->i_op->setxattr ||
+	    !root->d_inode->i_op->getxattr ||
+	    !root->d_sb ||
+	    !root->d_sb->s_op ||
+	    !root->d_sb->s_op->statfs ||
+	    !root->d_sb->s_op->sync_fs)
+		goto error_unsupported;
+
+	ret = -EROFS;
+	if (root->d_sb->s_flags & MS_RDONLY)
+		goto error_unsupported;
+
+	/* determine the security of the on-disk cache as this governs
+	 * security ID of files we create */
+	ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
+	if (ret < 0)
+		goto error_unsupported;
+
+	/* get the cache size and blocksize */
+	ret = vfs_statfs(root, &stats);
+	if (ret < 0)
+		goto error_unsupported;
+
+	ret = -ERANGE;
+	if (stats.f_bsize <= 0)
+		goto error_unsupported;
+
+	ret = -EOPNOTSUPP;
+	if (stats.f_bsize > PAGE_SIZE)
+		goto error_unsupported;
+
+	cache->bsize = stats.f_bsize;
+	cache->bshift = 0;
+	if (stats.f_bsize < PAGE_SIZE)
+		cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);
+
+	_debug("blksize %u (shift %u)",
+	       cache->bsize, cache->bshift);
+
+	_debug("size %llu, avail %llu",
+	       (unsigned long long) stats.f_blocks,
+	       (unsigned long long) stats.f_bavail);
+
+	/* set up caching limits */
+	do_div(stats.f_files, 100);
+	cache->fstop = stats.f_files * cache->fstop_percent;
+	cache->fcull = stats.f_files * cache->fcull_percent;
+	cache->frun  = stats.f_files * cache->frun_percent;
+
+	_debug("limits {%llu,%llu,%llu} files",
+	       (unsigned long long) cache->frun,
+	       (unsigned long long) cache->fcull,
+	       (unsigned long long) cache->fstop);
+
+	stats.f_blocks >>= cache->bshift;
+	do_div(stats.f_blocks, 100);
+	cache->bstop = stats.f_blocks * cache->bstop_percent;
+	cache->bcull = stats.f_blocks * cache->bcull_percent;
+	cache->brun  = stats.f_blocks * cache->brun_percent;
+
+	_debug("limits {%llu,%llu,%llu} blocks",
+	       (unsigned long long) cache->brun,
+	       (unsigned long long) cache->bcull,
+	       (unsigned long long) cache->bstop);
+
+	/* get the cache directory and check its type */
+	cachedir = cachefiles_get_directory(cache, root, "cache");
+	if (IS_ERR(cachedir)) {
+		ret = PTR_ERR(cachedir);
+		goto error_unsupported;
+	}
+
+	fsdef->dentry = cachedir;
+	fsdef->fscache.cookie = NULL;
+
+	ret = cachefiles_check_object_type(fsdef);
+	if (ret < 0)
+		goto error_unsupported;
+
+	/* get the graveyard directory */
+	graveyard = cachefiles_get_directory(cache, root, "graveyard");
+	if (IS_ERR(graveyard)) {
+		ret = PTR_ERR(graveyard);
+		goto error_unsupported;
+	}
+
+	cache->graveyard = graveyard;
+
+	/* publish the cache */
+	fscache_init_cache(&cache->cache,
+			   &cachefiles_cache_ops,
+			   "%s",
+			   fsdef->dentry->d_sb->s_id);
+
+	fscache_object_init(&fsdef->fscache, NULL, &cache->cache);
+
+	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
+	if (ret < 0)
+		goto error_add_cache;
+
+	/* done */
+	set_bit(CACHEFILES_READY, &cache->flags);
+	dput(root);
+
+	printk(KERN_INFO "CacheFiles:"
+	       " File cache on %s registered\n",
+	       cache->cache.identifier);
+
+	/* check how much space the cache has */
+	cachefiles_has_space(cache, 0, 0);
+	cachefiles_end_secure(cache, saved_cred);
+	return 0;
+
+error_add_cache:
+	dput(cache->graveyard);
+	cache->graveyard = NULL;
+error_unsupported:
+	mntput(cache->mnt);
+	cache->mnt = NULL;
+	dput(fsdef->dentry);
+	fsdef->dentry = NULL;
+	dput(root);
+error_open_root:
+	kmem_cache_free(cachefiles_object_jar, fsdef);
+error_root_object:
+	cachefiles_end_secure(cache, saved_cred);
+	kerror("Failed to register: %d", ret);
+	return ret;
+}
+
+/*
+ * unbind a cache on fd release
+ */
+void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
+{
+	_enter("");
+
+	if (test_bit(CACHEFILES_READY, &cache->flags)) {
+		printk(KERN_INFO "CacheFiles:"
+		       " File cache on %s unregistering\n",
+		       cache->cache.identifier);
+
+		fscache_withdraw_cache(&cache->cache);
+	}
+
+	dput(cache->graveyard);
+	mntput(cache->mnt);
+
+	kfree(cache->rootdirname);
+	kfree(cache->secctx);
+	kfree(cache->tag);
+
+	_leave("");
+}

fs/cachefiles/key.c

+/* Key to pathname encoder
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/slab.h>
+#include "internal.h"
+
+static const char cachefiles_charmap[64] =
+	"0123456789"			/* 0 - 9 */
+	"abcdefghijklmnopqrstuvwxyz"	/* 10 - 35 */
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZ"	/* 36 - 61 */
+	"_-"				/* 62 - 63 */
+	;
+
+static const char cachefiles_filecharmap[256] = {
+	/* we skip space and tab and control chars */
+	[33 ... 46] = 1,		/* '!' -> '.' */
+	/* we skip '/' as it's significant to pathwalk */
+	[48 ... 127] = 1,		/* '0' -> '~' */
+};
+
+/*
+ * turn the raw key into something cooked
+ * - the raw key should include the length in the two bytes at the front
+ * - the key may be up to 514 bytes in length (including the length word)
+ *   - "base64" encode the strange keys, mapping 3 bytes of raw to four of
+ *     cooked
+ *   - need to cut the cooked key into 252 char lengths (189 raw bytes)
+ */
+char *cachefiles_cook_key(const u8 *raw, int keylen, uint8_t type)
+{
+	unsigned char csum, ch;
+	unsigned int acc;
+	char *key;
+	int loop, len, max, seg, mark, print;
+
+	_enter(",%d", keylen);
+
+	BUG_ON(keylen < 2 || keylen > 514);
+
+	csum = raw[0] + raw[1];
+	print = 1;
+	for (loop = 2; loop < keylen; loop++) {
+		ch = raw[loop];
+		csum += ch;
+		print &= cachefiles_filecharmap[ch];
+	}
+
+	if (print) {
+		/* if the path is usable ASCII, then we render it directly */
+		max = keylen - 2;
+		max += 2;	/* two base64'd length chars on the front */
+		max += 5;	/* @checksum/M */
+		max += 3 * 2;	/* maximum number of segment dividers (".../M")
+				 * is ((514 + 251) / 252) = 3
+				 */
+		max += 1;	/* NUL on end */
+	} else {
+		/* calculate the maximum length of the cooked key */
+		keylen = (keylen + 2) / 3;
+
+		max = keylen * 4;
+		max += 5;	/* @checksum/M */
+		max += 3 * 2;	/* maximum number of segment dividers (".../M")
+				 * is ((514 + 188) / 189) = 3
+				 */
+		max += 1;	/* NUL on end */
+	}
+
+	max += 1;	/* 2nd NUL on end */
+
+	_debug("max: %d", max);
+
+	key = kmalloc(max, GFP_KERNEL);
+	if (!key)
+		return NULL;
+
+	len = 0;
+
+	/* build the cooked key */
+	sprintf(key, "@%02x%c+", (unsigned) csum, 0);
+	len = 5;
+	mark = len - 1;
+
+	if (print) {
+		acc = *(uint16_t *) raw;
+		raw += 2;
+
+		key[len + 1] = cachefiles_charmap[acc & 63];
+		acc >>= 6;
+		key[len] = cachefiles_charmap[acc & 63];
+		len += 2;
+
+		seg = 250;
+		for (loop = keylen; loop > 0; loop--) {
+			if (seg <= 0) {
+				key[len++] = '\0';
+				mark = len;
+				key[len++] = '+';
+				seg = 252;
+			}
+
+			key[len++] = *raw++;
+			ASSERT(len < max);
+		}
+
+		switch (type) {
+		case FSCACHE_COOKIE_TYPE_INDEX:		type = 'I';	break;
+		case FSCACHE_COOKIE_TYPE_DATAFILE:	type = 'D';	break;
+		default:				type = 'S';	break;
+		}
+	} else {
+		seg = 252;
+		for (loop = keylen; loop > 0; loop--) {
+			if (seg <= 0) {
+				key[len++] = '\0';
+				mark = len;
+				key[len++] = '+';
+				seg = 252;
+			}
+
+			acc = *raw++;
+			acc |= *raw++ << 8;
+			acc |= *raw++ << 16;
+
+			_debug("acc: %06x", acc);
+
+			key[len++] = cachefiles_charmap[acc & 63];
+			acc >>= 6;
+			key[len++] = cachefiles_charmap[acc & 63];
+			acc >>= 6;
+			key[len++] = cachefiles_charmap[acc & 63];
+			acc >>= 6;
+			key[len++] = cachefiles_charmap[acc & 63];
+
+			ASSERT(len < max);
+		}
+
+		switch (type) {
+		case FSCACHE_COOKIE_TYPE_INDEX:		type = 'J';	break;
+		case FSCACHE_COOKIE_TYPE_DATAFILE:	type = 'E';	break;
+		default:				type = 'T';	break;
+		}
+	}
+
+	key[mark] = type;
+	key[len++] = 0;
+	key[len] = 0;
+
+	_leave(" = %p %d", key, len);
+	return key;
+}

fs/cachefiles/main.c

+/* Network filesystem caching backend to use cache files on a premounted
+ * filesystem
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/completion.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/statfs.h>
+#include <linux/sysctl.h>
+#include <linux/miscdevice.h>
+#include "internal.h"
+
+unsigned cachefiles_debug;
+module_param_named(debug, cachefiles_debug, uint, S_IWUSR | S_IRUGO);
+MODULE_PARM_DESC(cachefiles_debug, "CacheFiles debugging mask");
+
+MODULE_DESCRIPTION("Mounted-filesystem based cache");
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_LICENSE("GPL");
+
+struct kmem_cache *cachefiles_object_jar;
+
+static struct miscdevice cachefiles_dev = {
+	.minor	= MISC_DYNAMIC_MINOR,
+	.name	= "cachefiles",
+	.fops	= &cachefiles_daemon_fops,
+};
+
+static void cachefiles_object_init_once(void *_object)
+{
+	struct cachefiles_object *object = _object;
+
+	memset(object, 0, sizeof(*object));
+	spin_lock_init(&object->work_lock);
+}
+
+/*
+ * initialise the fs caching module
+ */
+static int __init cachefiles_init(void)
+{
+	int ret;
+
+	ret = misc_register(&cachefiles_dev);
+	if (ret < 0)
+		goto error_dev;
+
+	/* create an object jar */
+	ret = -ENOMEM;
+	cachefiles_object_jar =
+		kmem_cache_create("cachefiles_object_jar",
+				  sizeof(struct cachefiles_object),
+				  0,
+				  SLAB_HWCACHE_ALIGN,
+				  cachefiles_object_init_once);
+	if (!cachefiles_object_jar) {
+		printk(KERN_NOTICE
+		       "CacheFiles: Failed to allocate an object jar\n");
+		goto error_object_jar;
+	}
+
+	ret = cachefiles_proc_init();
+	if (ret < 0)
+		goto error_proc;
+
+	printk(KERN_INFO "CacheFiles: Loaded\n");
+	return 0;
+
+error_proc:
+	kmem_cache_destroy(cachefiles_object_jar);
+error_object_jar:
+	misc_deregister(&cachefiles_dev);
+error_dev:
+	kerror("failed to register: %d", ret);
+	return ret;
+}
+
+fs_initcall(cachefiles_init);
+
+/*
+ * clean up on module removal
+ */
+static void __exit cachefiles_exit(void)
+{
+	printk(KERN_INFO "CacheFiles: Unloading\n");
+
+	cachefiles_proc_cleanup();
+	kmem_cache_destroy(cachefiles_object_jar);
+	misc_deregister(&cachefiles_dev);
+}
+
+module_exit(cachefiles_exit);

fs/fscache/Kconfig

+
+config FSCACHE
+	tristate "General filesystem local caching manager"
+	depends on EXPERIMENTAL
+	select SLOW_WORK
+	help
+	  This option enables a generic filesystem caching manager that can be
+	  used by various network and other filesystems to cache data locally.
+	  Different sorts of caches can be plugged in, depending on the
+	  resources available.
+
+	  See Documentation/filesystems/caching/fscache.txt for more information.
+
+config FSCACHE_STATS
+	bool "Gather statistical information on local caching"
+	depends on FSCACHE && PROC_FS
+	help
+	  This option causes statistical information to be gathered on local
+	  caching and exported through file:
+
+		/proc/fs/fscache/stats
+
+	  The gathering of statistics adds a certain amount of overhead to
+	  execution as there are a quite a few stats gathered, and on a
+	  multi-CPU system these may be on cachelines that keep bouncing
+	  between CPUs.  On the other hand, the stats are very useful for
+	  debugging purposes.  Saying 'Y' here is recommended.
+
+	  See Documentation/filesystems/caching/fscache.txt for more information.
+
+config FSCACHE_HISTOGRAM
+	bool "Gather latency information on local caching"
+	depends on FSCACHE && PROC_FS
+	help
+	  This option causes latency information to be gathered on local
+	  caching and exported through file:
+
+		/proc/fs/fscache/histogram
+
+	  The generation of this histogram adds a certain amount of overhead to
+	  execution as there are a number of points at which data is gathered,
+	  and on a multi-CPU system these may be on cachelines that keep
+	  bouncing between CPUs.  On the other hand, the histogram may be
+	  useful for debugging purposes.  Saying 'N' here is recommended.
+
+	  See Documentation/filesystems/caching/fscache.txt for more information.
+
+config FSCACHE_DEBUG
+	bool "Debug FS-Cache"
+	depends on FSCACHE
+	help
+	  This permits debugging to be dynamically enabled in the local caching
+	  management module.  If this is set, the debugging output may be
+	  enabled by setting bits in /sys/modules/fscache/parameter/debug.
+
+	  See Documentation/filesystems/caching/fscache.txt for more information.

fs/fscache/Makefile

+#
+# Makefile for general filesystem caching code
+#
+
+fscache-y := \
+	cache.o \
+	cookie.o \
+	fsdef.o \
+	main.o \
+	netfs.o \
+	object.o \
+	operation.o \
+	page.o
+
+fscache-$(CONFIG_PROC_FS) += proc.o
+fscache-$(CONFIG_FSCACHE_STATS) += stats.o
+fscache-$(CONFIG_FSCACHE_HISTOGRAM) += histogram.o
+
+obj-$(CONFIG_FSCACHE) := fscache.o

fs/nfs/Kconfig

@@ -84,3 +84,11 @@ config ROOT_NFS
 	  <file:Documentation/filesystems/nfsroot.txt>.
 
 	  Most people say N here.
+
+config NFS_FSCACHE
+	bool "Provide NFS client caching support (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+	depends on NFS_FS=m && FSCACHE || NFS_FS=y && FSCACHE=y
+	help
+	  Say Y here if you want NFS data to be cached locally on disc through
+	  the general filesystem cache manager