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diff --git a/include/linux/fscache.h b/include/linux/fscache.h
new file mode 100644
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+/* General filesystem caching interface
+ *
+ * Copyright (C) 2004-2007 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 License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * NOTE!!! See:
+ *
+ *      Documentation/filesystems/caching/netfs-api.txt
+ *
+ * for a description of the network filesystem interface declared here.
+ */
+
+#ifndef _LINUX_FSCACHE_H
+#define _LINUX_FSCACHE_H
+
+#include <linux/fs.h>
+#include <linux/list.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+
+#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
+#define fscache_available() (1)
+#define fscache_cookie_valid(cookie) (cookie)
+#else
+#define fscache_available() (0)
+#define fscache_cookie_valid(cookie) (0)
+#endif
+
+
+/*
+ * overload PG_private_2 to give us PG_fscache - this is used to indicate that
+ * a page is currently backed by a local disk cache
+ */
+#define PageFsCache(page)               PagePrivate2((page))
+#define SetPageFsCache(page)            SetPagePrivate2((page))
+#define ClearPageFsCache(page)          ClearPagePrivate2((page))
+#define TestSetPageFsCache(page)        TestSetPagePrivate2((page))
+#define TestClearPageFsCache(page)      TestClearPagePrivate2((page))
+
+/* pattern used to fill dead space in an index entry */
+#define FSCACHE_INDEX_DEADFILL_PATTERN 0x79
+
+struct pagevec;
+struct fscache_cache_tag;
+struct fscache_cookie;
+struct fscache_netfs;
+
+typedef void (*fscache_rw_complete_t)(struct page *page,
+                                      void *context,
+                                      int error);
+
+/* result of index entry consultation */
+enum fscache_checkaux {
+        FSCACHE_CHECKAUX_OKAY,          /* entry okay as is */
+        FSCACHE_CHECKAUX_NEEDS_UPDATE,  /* entry requires update */
+        FSCACHE_CHECKAUX_OBSOLETE,      /* entry requires deletion */
+};
+
+/*
+ * fscache cookie definition
+ */
+struct fscache_cookie_def {
+        /* name of cookie type */
+        char name[16];
+
+        /* cookie type */
+        uint8_t type;
+#define FSCACHE_COOKIE_TYPE_INDEX       0
+#define FSCACHE_COOKIE_TYPE_DATAFILE    1
+
+        /* select the cache into which to insert an entry in this index
+         * - optional
+         * - should return a cache identifier or NULL to cause the cache to be
+         *   inherited from the parent if possible or the first cache picked
+         *   for a non-index file if not
+         */
+        struct fscache_cache_tag *(*select_cache)(
+                const void *parent_netfs_data,
+                const void *cookie_netfs_data);
+
+        /* get an index key
+         * - should store the key data in the buffer
+         * - should return the amount of amount stored
+         * - not permitted to return an error
+         * - the netfs data from the cookie being used as the source is
+         *   presented
+         */
+        uint16_t (*get_key)(const void *cookie_netfs_data,
+                            void *buffer,
+                            uint16_t bufmax);
+
+        /* get certain file attributes from the netfs data
+         * - this function can be absent for an index
+         * - not permitted to return an error
+         * - the netfs data from the cookie being used as the source is
+         *   presented
+         */
+        void (*get_attr)(const void *cookie_netfs_data, uint64_t *size);
+
+        /* get the auxilliary data from netfs data
+         * - this function can be absent if the index carries no state data
+         * - should store the auxilliary data in the buffer
+         * - should return the amount of amount stored
+         * - not permitted to return an error
+         * - the netfs data from the cookie being used as the source is
+         *   presented
+         */
+        uint16_t (*get_aux)(const void *cookie_netfs_data,
+                            void *buffer,
+                            uint16_t bufmax);
+
+        /* consult the netfs about the state of an object
+         * - this function can be absent if the index carries no state data
+         * - the netfs data from the cookie being used as the target is
+         *   presented, as is the auxilliary data
+         */
+        enum fscache_checkaux (*check_aux)(void *cookie_netfs_data,
+                                           const void *data,
+                                           uint16_t datalen);
+
+        /* get an extra reference on a read context
+         * - this function can be absent if the completion function doesn't
+         *   require a context
+         */
+        void (*get_context)(void *cookie_netfs_data, void *context);
+
+        /* release an extra reference on a read context
+         * - this function can be absent if the completion function doesn't
+         *   require a context
+         */
+        void (*put_context)(void *cookie_netfs_data, void *context);
+
+        /* indicate pages that now have cache metadata retained
+         * - this function should mark the specified pages as now being cached
+         * - the pages will have been marked with PG_fscache before this is
+         *   called, so this is optional
+         */
+        void (*mark_pages_cached)(void *cookie_netfs_data,
+                                  struct address_space *mapping,
+                                  struct pagevec *cached_pvec);
+
+        /* indicate the cookie is no longer cached
+         * - this function is called when the backing store currently caching
+         *   a cookie is removed
+         * - the netfs should use this to clean up any markers indicating
+         *   cached pages
+         * - this is mandatory for any object that may have data
+         */
+        void (*now_uncached)(void *cookie_netfs_data);
+};
+
+/*
+ * fscache cached network filesystem type
+ * - name, version and ops must be filled in before registration
+ * - all other fields will be set during registration
+ */
+struct fscache_netfs {
+        uint32_t                        version;        /* indexing version */
+        const char                      *name;          /* filesystem name */
+        struct fscache_cookie           *primary_index;
+        struct list_head                link;           /* internal link */
+};
+
+/*
+ * slow-path functions for when there is actually caching available, and the
+ * netfs does actually have a valid token
+ * - these are not to be called directly
+ * - these are undefined symbols when FS-Cache is not configured and the
+ *   optimiser takes care of not using them
+ */
+extern int __fscache_register_netfs(struct fscache_netfs *);
+extern void __fscache_unregister_netfs(struct fscache_netfs *);
+extern struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *);
+extern void __fscache_release_cache_tag(struct fscache_cache_tag *);
+
+extern struct fscache_cookie *__fscache_acquire_cookie(
+        struct fscache_cookie *,
+        const struct fscache_cookie_def *,
+        void *);
+extern void __fscache_relinquish_cookie(struct fscache_cookie *, int);
+extern void __fscache_update_cookie(struct fscache_cookie *);
+extern int __fscache_attr_changed(struct fscache_cookie *);
+extern int __fscache_read_or_alloc_page(struct fscache_cookie *,
+                                        struct page *,
+                                        fscache_rw_complete_t,
+                                        void *,
+                                        gfp_t);
+extern int __fscache_read_or_alloc_pages(struct fscache_cookie *,
+                                         struct address_space *,
+                                         struct list_head *,
+                                         unsigned *,
+                                         fscache_rw_complete_t,
+                                         void *,
+                                         gfp_t);
+extern int __fscache_alloc_page(struct fscache_cookie *, struct page *, gfp_t);
+extern int __fscache_write_page(struct fscache_cookie *, struct page *, gfp_t);
+extern void __fscache_uncache_page(struct fscache_cookie *, struct page *);
+extern bool __fscache_check_page_write(struct fscache_cookie *, struct page *);
+extern void __fscache_wait_on_page_write(struct fscache_cookie *, struct page *);
+
+/**
+ * fscache_register_netfs - Register a filesystem as desiring caching services
+ * @netfs: The description of the filesystem
+ *
+ * Register a filesystem as desiring caching services if they're available.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+int fscache_register_netfs(struct fscache_netfs *netfs)
+{
+        if (fscache_available())
+                return __fscache_register_netfs(netfs);
+        else
+                return 0;
+}
+
+/**
+ * fscache_unregister_netfs - Indicate that a filesystem no longer desires
+ * caching services
+ * @netfs: The description of the filesystem
+ *
+ * Indicate that a filesystem no longer desires caching services for the
+ * moment.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_unregister_netfs(struct fscache_netfs *netfs)
+{
+        if (fscache_available())
+                __fscache_unregister_netfs(netfs);
+}
+
+/**
+ * fscache_lookup_cache_tag - Look up a cache tag
+ * @name: The name of the tag to search for
+ *
+ * Acquire a specific cache referral tag that can be used to select a specific
+ * cache in which to cache an index.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name)
+{
+        if (fscache_available())
+                return __fscache_lookup_cache_tag(name);
+        else
+                return NULL;
+}
+
+/**
+ * fscache_release_cache_tag - Release a cache tag
+ * @tag: The tag to release
+ *
+ * Release a reference to a cache referral tag previously looked up.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_release_cache_tag(struct fscache_cache_tag *tag)
+{
+        if (fscache_available())
+                __fscache_release_cache_tag(tag);
+}
+
+/**
+ * fscache_acquire_cookie - Acquire a cookie to represent a cache object
+ * @parent: The cookie that's to be the parent of this one
+ * @def: A description of the cache object, including callback operations
+ * @netfs_data: An arbitrary piece of data to be kept in the cookie to
+ * represent the cache object to the netfs
+ *
+ * This function is used to inform FS-Cache about part of an index hierarchy
+ * that can be used to locate files.  This is done by requesting a cookie for
+ * each index in the path to the file.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+struct fscache_cookie *fscache_acquire_cookie(
+        struct fscache_cookie *parent,
+        const struct fscache_cookie_def *def,
+        void *netfs_data)
+{
+        if (fscache_cookie_valid(parent))
+                return __fscache_acquire_cookie(parent, def, netfs_data);
+        else
+                return NULL;
+}
+
+/**
+ * fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding
+ * it
+ * @cookie: The cookie being returned
+ * @retire: True if the cache object the cookie represents is to be discarded
+ *
+ * This function returns a cookie to the cache, forcibly discarding the
+ * associated cache object if retire is set to true.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
+{
+        if (fscache_cookie_valid(cookie))
+                __fscache_relinquish_cookie(cookie, retire);
+}
+
+/**
+ * fscache_update_cookie - Request that a cache object be updated
+ * @cookie: The cookie representing the cache object
+ *
+ * Request an update of the index data for the cache object associated with the
+ * cookie.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_update_cookie(struct fscache_cookie *cookie)
+{
+        if (fscache_cookie_valid(cookie))
+                __fscache_update_cookie(cookie);
+}
+
+/**
+ * fscache_pin_cookie - Pin a data-storage cache object in its cache
+ * @cookie: The cookie representing the cache object
+ *
+ * Permit data-storage cache objects to be pinned in the cache.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+int fscache_pin_cookie(struct fscache_cookie *cookie)
+{
+        return -ENOBUFS;
+}
+
+/**
+ * fscache_pin_cookie - Unpin a data-storage cache object in its cache
+ * @cookie: The cookie representing the cache object
+ *
+ * Permit data-storage cache objects to be unpinned from the cache.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_unpin_cookie(struct fscache_cookie *cookie)
+{
+}
+
+/**
+ * fscache_attr_changed - Notify cache that an object's attributes changed
+ * @cookie: The cookie representing the cache object
+ *
+ * Send a notification to the cache indicating that an object's attributes have
+ * changed.  This includes the data size.  These attributes will be obtained
+ * through the get_attr() cookie definition op.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+int fscache_attr_changed(struct fscache_cookie *cookie)
+{
+        if (fscache_cookie_valid(cookie))
+                return __fscache_attr_changed(cookie);
+        else
+                return -ENOBUFS;
+}
+
+/**
+ * fscache_reserve_space - Reserve data space for a cached object
+ * @cookie: The cookie representing the cache object
+ * @i_size: The amount of space to be reserved
+ *
+ * Reserve an amount of space in the cache for the cache object attached to a
+ * cookie so that a write to that object within the space can always be
+ * honoured.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size)
+{
+        return -ENOBUFS;
+}
+
+/**
+ * fscache_read_or_alloc_page - Read a page from the cache or allocate a block
+ * in which to store it
+ * @cookie: The cookie representing the cache object
+ * @page: The netfs page to fill if possible
+ * @end_io_func: The callback to invoke when and if the page is filled
+ * @context: An arbitrary piece of data to pass on to end_io_func()
+ * @gfp: The conditions under which memory allocation should be made
+ *
+ * Read a page from the cache, or if that's not possible make a potential
+ * one-block reservation in the cache into which the page may be stored once
+ * fetched from the server.
+ *
+ * If the page is not backed by the cache object, or if it there's some reason
+ * it can't be, -ENOBUFS will be returned and nothing more will be done for
+ * that page.
+ *
+ * Else, if that page is backed by the cache, a read will be initiated directly
+ * to the netfs's page and 0 will be returned by this function.  The
+ * end_io_func() callback will be invoked when the operation terminates on a
+ * completion or failure.  Note that the callback may be invoked before the
+ * return.
+ *
+ * Else, if the page is unbacked, -ENODATA is returned and a block may have
+ * been allocated in the cache.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
+                               struct page *page,
+                               fscache_rw_complete_t end_io_func,
+                               void *context,
+                               gfp_t gfp)
+{
+        if (fscache_cookie_valid(cookie))
+                return __fscache_read_or_alloc_page(cookie, page, end_io_func,
+                                                    context, gfp);
+        else
+                return -ENOBUFS;
+}
+
+/**
+ * fscache_read_or_alloc_pages - Read pages from the cache and/or allocate
+ * blocks in which to store them
+ * @cookie: The cookie representing the cache object
+ * @mapping: The netfs inode mapping to which the pages will be attached
+ * @pages: A list of potential netfs pages to be filled
+ * @end_io_func: The callback to invoke when and if each page is filled
+ * @context: An arbitrary piece of data to pass on to end_io_func()
+ * @gfp: The conditions under which memory allocation should be made
+ *
+ * Read a set of pages from the cache, or if that's not possible, attempt to
+ * make a potential one-block reservation for each page in the cache into which
+ * that page may be stored once fetched from the server.
+ *
+ * If some pages are not backed by the cache object, or if it there's some
+ * reason they can't be, -ENOBUFS will be returned and nothing more will be
+ * done for that pages.
+ *
+ * Else, if some of the pages are backed by the cache, a read will be initiated
+ * directly to the netfs's page and 0 will be returned by this function.  The
+ * end_io_func() callback will be invoked when the operation terminates on a
+ * completion or failure.  Note that the callback may be invoked before the
+ * return.
+ *
+ * Else, if a page is unbacked, -ENODATA is returned and a block may have
+ * been allocated in the cache.
+ *
+ * Because the function may want to return all of -ENOBUFS, -ENODATA and 0 in
+ * regard to different pages, the return values are prioritised in that order.
+ * Any pages submitted for reading are removed from the pages list.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
+                                struct address_space *mapping,
+                                struct list_head *pages,
+                                unsigned *nr_pages,
+                                fscache_rw_complete_t end_io_func,
+                                void *context,
+                                gfp_t gfp)
+{
+        if (fscache_cookie_valid(cookie))
+                return __fscache_read_or_alloc_pages(cookie, mapping, pages,
+                                                     nr_pages, end_io_func,
+                                                     context, gfp);
+        else
+                return -ENOBUFS;
+}
+
+/**
+ * fscache_alloc_page - Allocate a block in which to store a page
+ * @cookie: The cookie representing the cache object
+ * @page: The netfs page to allocate a page for
+ * @gfp: The conditions under which memory allocation should be made
+ *
+ * Request Allocation a block in the cache in which to store a netfs page
+ * without retrieving any contents from the cache.
+ *
+ * If the page is not backed by a file then -ENOBUFS will be returned and
+ * nothing more will be done, and no reservation will be made.
+ *
+ * Else, a block will be allocated if one wasn't already, and 0 will be
+ * returned
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+int fscache_alloc_page(struct fscache_cookie *cookie,
+                       struct page *page,
+                       gfp_t gfp)
+{
+        if (fscache_cookie_valid(cookie))
+                return __fscache_alloc_page(cookie, page, gfp);
+        else
+                return -ENOBUFS;
+}
+
+/**
+ * fscache_write_page - Request storage of a page in the cache
+ * @cookie: The cookie representing the cache object
+ * @page: The netfs page to store
+ * @gfp: The conditions under which memory allocation should be made
+ *
+ * Request the contents of the netfs page be written into the cache.  This
+ * request may be ignored if no cache block is currently allocated, in which
+ * case it will return -ENOBUFS.
+ *
+ * If a cache block was already allocated, a write will be initiated and 0 will
+ * be returned.  The PG_fscache_write page bit is set immediately and will then
+ * be cleared at the completion of the write to indicate the success or failure
+ * of the operation.  Note that the completion may happen before the return.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+int fscache_write_page(struct fscache_cookie *cookie,
+                       struct page *page,
+                       gfp_t gfp)
+{
+        if (fscache_cookie_valid(cookie))
+                return __fscache_write_page(cookie, page, gfp);
+        else
+                return -ENOBUFS;
+}
+
+/**
+ * fscache_uncache_page - Indicate that caching is no longer required on a page
+ * @cookie: The cookie representing the cache object
+ * @page: The netfs page that was being cached.
+ *
+ * Tell the cache that we no longer want a page to be cached and that it should
+ * remove any knowledge of the netfs page it may have.
+ *
+ * Note that this cannot cancel any outstanding I/O operations between this
+ * page and the cache.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_uncache_page(struct fscache_cookie *cookie,
+                          struct page *page)
+{
+        if (fscache_cookie_valid(cookie))
+                __fscache_uncache_page(cookie, page);
+}
+
+/**
+ * fscache_check_page_write - Ask if a page is being writing to the cache
+ * @cookie: The cookie representing the cache object
+ * @page: The netfs page that is being cached.
+ *
+ * Ask the cache if a page is being written to the cache.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+bool fscache_check_page_write(struct fscache_cookie *cookie,
+                              struct page *page)
+{
+        if (fscache_cookie_valid(cookie))
+                return __fscache_check_page_write(cookie, page);
+        return false;
+}
+
+/**
+ * fscache_wait_on_page_write - Wait for a page to complete writing to the cache
+ * @cookie: The cookie representing the cache object
+ * @page: The netfs page that is being cached.
+ *
+ * Ask the cache to wake us up when a page is no longer being written to the
+ * cache.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_wait_on_page_write(struct fscache_cookie *cookie,
+                                struct page *page)
+{
+        if (fscache_cookie_valid(cookie))
+                __fscache_wait_on_page_write(cookie, page);
+}
+
+#endif /* _LINUX_FSCACHE_H */