Edit File: fscache.h
/* 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 data 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 auxiliary data from netfs data * - this function can be absent if the index carries no state data * - should store the auxiliary 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 auxiliary 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 page that now have cache metadata retained * - this function should mark the specified page as now being cached * - the page will have been marked with PG_fscache before this is * called, so this is optional */ void (*mark_page_cached)(void *cookie_netfs_data, struct address_space *mapping, struct page *page); /* 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 */ }; /* * data file or index object cookie * - a file will only appear in one cache * - a request to cache a file may or may not be honoured, subject to * constraints such as disk space * - indices are created on disk just-in-time */ struct fscache_cookie { atomic_t usage; /* number of users of this cookie */ atomic_t n_children; /* number of children of this cookie */ atomic_t n_active; /* number of active users of netfs ptrs */ spinlock_t lock; spinlock_t stores_lock; /* lock on page store tree */ struct hlist_head backing_objects; /* object(s) backing this file/index */ const struct fscache_cookie_def *def; /* definition */ struct fscache_cookie *parent; /* parent of this entry */ void *netfs_data; /* back pointer to netfs */ struct radix_tree_root stores; /* pages to be stored on this cookie */ #define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */ #define FSCACHE_COOKIE_STORING_TAG 1 /* pages tag: writing to cache */ unsigned long flags; #define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */ #define FSCACHE_COOKIE_NO_DATA_YET 1 /* T if new object with no cached data yet */ #define FSCACHE_COOKIE_UNAVAILABLE 2 /* T if cookie is unavailable (error, etc) */ #define FSCACHE_COOKIE_INVALIDATING 3 /* T if cookie is being invalidated */ #define FSCACHE_COOKIE_RELINQUISHED 4 /* T if cookie has been relinquished */ #define FSCACHE_COOKIE_ENABLED 5 /* T if cookie is enabled */ #define FSCACHE_COOKIE_ENABLEMENT_LOCK 6 /* T if cookie is being en/disabled */ }; static inline bool fscache_cookie_enabled(struct fscache_cookie *cookie) { return test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags); } /* * 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 *, bool); extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool); extern int __fscache_check_consistency(struct fscache_cookie *); extern void __fscache_update_cookie(struct fscache_cookie *); extern int __fscache_attr_changed(struct fscache_cookie *); extern void __fscache_invalidate(struct fscache_cookie *); extern void __fscache_wait_on_invalidate(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 *); extern bool __fscache_maybe_release_page(struct fscache_cookie *, struct page *, gfp_t); extern void __fscache_uncache_all_inode_pages(struct fscache_cookie *, struct inode *); extern void __fscache_readpages_cancel(struct fscache_cookie *cookie, struct list_head *pages); extern void __fscache_disable_cookie(struct fscache_cookie *, bool); extern void __fscache_enable_cookie(struct fscache_cookie *, bool (*)(void *), void *); /** * 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 * @enable: Whether or not to enable a data cookie immediately * * 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, bool enable) { if (fscache_cookie_valid(parent) && fscache_cookie_enabled(parent)) return __fscache_acquire_cookie(parent, def, netfs_data, enable); 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, bool retire) { if (fscache_cookie_valid(cookie)) __fscache_relinquish_cookie(cookie, retire); } /** * fscache_check_consistency - Request that if the cache is updated * @cookie: The cookie representing the cache object * * Request an consistency check from fscache, which passes the request * to the backing cache. * * Returns 0 if consistent and -ESTALE if inconsistent. May also * return -ENOMEM and -ERESTARTSYS. */ static inline int fscache_check_consistency(struct fscache_cookie *cookie) { if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) return __fscache_check_consistency(cookie); else return 0; } /** * 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_cookie_enabled(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) && fscache_cookie_enabled(cookie)) return __fscache_attr_changed(cookie); else return -ENOBUFS; } /** * fscache_invalidate - Notify cache that an object needs invalidation * @cookie: The cookie representing the cache object * * Notify the cache that an object is needs to be invalidated and that it * should abort any retrievals or stores it is doing on the cache. The object * is then marked non-caching until such time as the invalidation is complete. * * This can be called with spinlocks held. * * See Documentation/filesystems/caching/netfs-api.txt for a complete * description. */ static inline void fscache_invalidate(struct fscache_cookie *cookie) { if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) __fscache_invalidate(cookie); } /** * fscache_wait_on_invalidate - Wait for invalidation to complete * @cookie: The cookie representing the cache object * * Wait for the invalidation of an object to complete. * * See Documentation/filesystems/caching/netfs-api.txt for a complete * description. */ static inline void fscache_wait_on_invalidate(struct fscache_cookie *cookie) { if (fscache_cookie_valid(cookie)) __fscache_wait_on_invalidate(cookie); } /** * 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) && fscache_cookie_enabled(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 * @nr_pages: Number of pages to be read and/or allocated * @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) && fscache_cookie_enabled(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) && fscache_cookie_enabled(cookie)) return __fscache_alloc_page(cookie, page, gfp); else return -ENOBUFS; } /** * fscache_readpages_cancel - Cancel read/alloc on pages * @cookie: The cookie representing the inode's cache object. * @pages: The netfs pages that we canceled write on in readpages() * * Uncache/unreserve the pages reserved earlier in readpages() via * fscache_readpages_or_alloc() and similar. In most successful caches in * readpages() this doesn't do anything. In cases when the underlying netfs's * readahead failed we need to clean up the pagelist (unmark and uncache). * * This function may sleep as it may have to clean up disk state. */ static inline void fscache_readpages_cancel(struct fscache_cookie *cookie, struct list_head *pages) { if (fscache_cookie_valid(cookie)) __fscache_readpages_cancel(cookie, pages); } /** * 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) && fscache_cookie_enabled(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); } /** * fscache_maybe_release_page - Consider releasing a page, cancelling a store * @cookie: The cookie representing the cache object * @page: The netfs page that is being cached. * @gfp: The gfp flags passed to releasepage() * * Consider releasing a page for the vmscan algorithm, on behalf of the netfs's * releasepage() call. A storage request on the page may cancelled if it is * not currently being processed. * * The function returns true if the page no longer has a storage request on it, * and false if a storage request is left in place. If true is returned, the * page will have been passed to fscache_uncache_page(). If false is returned * the page cannot be freed yet. */ static inline bool fscache_maybe_release_page(struct fscache_cookie *cookie, struct page *page, gfp_t gfp) { if (fscache_cookie_valid(cookie) && PageFsCache(page)) return __fscache_maybe_release_page(cookie, page, gfp); return false; } /** * fscache_uncache_all_inode_pages - Uncache all an inode's pages * @cookie: The cookie representing the inode's cache object. * @inode: The inode to uncache pages from. * * Uncache all the pages in an inode that are marked PG_fscache, assuming them * to be associated with the given cookie. * * This function may sleep. It will wait for pages that are being written out * and will wait whilst the PG_fscache mark is removed by the cache. */ static inline void fscache_uncache_all_inode_pages(struct fscache_cookie *cookie, struct inode *inode) { if (fscache_cookie_valid(cookie)) __fscache_uncache_all_inode_pages(cookie, inode); } /** * fscache_disable_cookie - Disable a cookie * @cookie: The cookie representing the cache object * @invalidate: Invalidate the backing object * * Disable a cookie from accepting further alloc, read, write, invalidate, * update or acquire operations. Outstanding operations can still be waited * upon and pages can still be uncached and the cookie relinquished. * * This will not return until all outstanding operations have completed. * * If @invalidate is set, then the backing object will be invalidated and * detached, otherwise it will just be detached. */ static inline void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate) { if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie)) __fscache_disable_cookie(cookie, invalidate); } /** * fscache_enable_cookie - Reenable a cookie * @cookie: The cookie representing the cache object * @can_enable: A function to permit enablement once lock is held * @data: Data for can_enable() * * Reenable a previously disabled cookie, allowing it to accept further alloc, * read, write, invalidate, update or acquire operations. An attempt will be * made to immediately reattach the cookie to a backing object. * * The can_enable() function is called (if not NULL) once the enablement lock * is held to rule on whether enablement is still permitted to go ahead. */ static inline void fscache_enable_cookie(struct fscache_cookie *cookie, bool (*can_enable)(void *data), void *data) { if (fscache_cookie_valid(cookie) && !fscache_cookie_enabled(cookie)) __fscache_enable_cookie(cookie, can_enable, data); } #endif /* _LINUX_FSCACHE_H */