1 /* General filesystem caching interface
3 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
13 * Documentation/filesystems/caching/netfs-api.txt
15 * for a description of the network filesystem interface declared here.
18 #ifndef _LINUX_FSCACHE_H
19 #define _LINUX_FSCACHE_H
22 #include <linux/list.h>
23 #include <linux/pagemap.h>
24 #include <linux/pagevec.h>
26 #if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
27 #define fscache_available() (1)
28 #define fscache_cookie_valid(cookie) (cookie)
30 #define fscache_available() (0)
31 #define fscache_cookie_valid(cookie) (0)
36 * overload PG_private_2 to give us PG_fscache - this is used to indicate that
37 * a page is currently backed by a local disk cache
39 #define PageFsCache(page) PagePrivate2((page))
40 #define SetPageFsCache(page) SetPagePrivate2((page))
41 #define ClearPageFsCache(page) ClearPagePrivate2((page))
42 #define TestSetPageFsCache(page) TestSetPagePrivate2((page))
43 #define TestClearPageFsCache(page) TestClearPagePrivate2((page))
45 /* pattern used to fill dead space in an index entry */
46 #define FSCACHE_INDEX_DEADFILL_PATTERN 0x79
49 struct fscache_cache_tag
;
50 struct fscache_cookie
;
53 typedef void (*fscache_rw_complete_t
)(struct page
*page
,
57 /* result of index entry consultation */
58 enum fscache_checkaux
{
59 FSCACHE_CHECKAUX_OKAY
, /* entry okay as is */
60 FSCACHE_CHECKAUX_NEEDS_UPDATE
, /* entry requires update */
61 FSCACHE_CHECKAUX_OBSOLETE
, /* entry requires deletion */
65 * fscache cookie definition
67 struct fscache_cookie_def
{
68 /* name of cookie type */
73 #define FSCACHE_COOKIE_TYPE_INDEX 0
74 #define FSCACHE_COOKIE_TYPE_DATAFILE 1
76 /* select the cache into which to insert an entry in this index
78 * - should return a cache identifier or NULL to cause the cache to be
79 * inherited from the parent if possible or the first cache picked
80 * for a non-index file if not
82 struct fscache_cache_tag
*(*select_cache
)(
83 const void *parent_netfs_data
,
84 const void *cookie_netfs_data
);
87 * - should store the key data in the buffer
88 * - should return the amount of data stored
89 * - not permitted to return an error
90 * - the netfs data from the cookie being used as the source is
93 uint16_t (*get_key
)(const void *cookie_netfs_data
,
97 /* get certain file attributes from the netfs data
98 * - this function can be absent for an index
99 * - not permitted to return an error
100 * - the netfs data from the cookie being used as the source is
103 void (*get_attr
)(const void *cookie_netfs_data
, uint64_t *size
);
105 /* get the auxiliary data from netfs data
106 * - this function can be absent if the index carries no state data
107 * - should store the auxiliary data in the buffer
108 * - should return the amount of amount stored
109 * - not permitted to return an error
110 * - the netfs data from the cookie being used as the source is
113 uint16_t (*get_aux
)(const void *cookie_netfs_data
,
117 /* consult the netfs about the state of an object
118 * - this function can be absent if the index carries no state data
119 * - the netfs data from the cookie being used as the target is
120 * presented, as is the auxiliary data
122 enum fscache_checkaux (*check_aux
)(void *cookie_netfs_data
,
126 /* get an extra reference on a read context
127 * - this function can be absent if the completion function doesn't
130 void (*get_context
)(void *cookie_netfs_data
, void *context
);
132 /* release an extra reference on a read context
133 * - this function can be absent if the completion function doesn't
136 void (*put_context
)(void *cookie_netfs_data
, void *context
);
138 /* indicate page that now have cache metadata retained
139 * - this function should mark the specified page as now being cached
140 * - the page will have been marked with PG_fscache before this is
141 * called, so this is optional
143 void (*mark_page_cached
)(void *cookie_netfs_data
,
144 struct address_space
*mapping
,
147 /* indicate the cookie is no longer cached
148 * - this function is called when the backing store currently caching
149 * a cookie is removed
150 * - the netfs should use this to clean up any markers indicating
152 * - this is mandatory for any object that may have data
154 void (*now_uncached
)(void *cookie_netfs_data
);
158 * fscache cached network filesystem type
159 * - name, version and ops must be filled in before registration
160 * - all other fields will be set during registration
162 struct fscache_netfs
{
163 uint32_t version
; /* indexing version */
164 const char *name
; /* filesystem name */
165 struct fscache_cookie
*primary_index
;
166 struct list_head link
; /* internal link */
170 * data file or index object cookie
171 * - a file will only appear in one cache
172 * - a request to cache a file may or may not be honoured, subject to
173 * constraints such as disk space
174 * - indices are created on disk just-in-time
176 struct fscache_cookie
{
177 atomic_t usage
; /* number of users of this cookie */
178 atomic_t n_children
; /* number of children of this cookie */
179 atomic_t n_active
; /* number of active users of netfs ptrs */
181 spinlock_t stores_lock
; /* lock on page store tree */
182 struct hlist_head backing_objects
; /* object(s) backing this file/index */
183 const struct fscache_cookie_def
*def
; /* definition */
184 struct fscache_cookie
*parent
; /* parent of this entry */
185 void *netfs_data
; /* back pointer to netfs */
186 struct radix_tree_root stores
; /* pages to be stored on this cookie */
187 #define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */
188 #define FSCACHE_COOKIE_STORING_TAG 1 /* pages tag: writing to cache */
191 #define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */
192 #define FSCACHE_COOKIE_NO_DATA_YET 1 /* T if new object with no cached data yet */
193 #define FSCACHE_COOKIE_UNAVAILABLE 2 /* T if cookie is unavailable (error, etc) */
194 #define FSCACHE_COOKIE_INVALIDATING 3 /* T if cookie is being invalidated */
195 #define FSCACHE_COOKIE_RELINQUISHED 4 /* T if cookie has been relinquished */
196 #define FSCACHE_COOKIE_ENABLED 5 /* T if cookie is enabled */
197 #define FSCACHE_COOKIE_ENABLEMENT_LOCK 6 /* T if cookie is being en/disabled */
200 static inline bool fscache_cookie_enabled(struct fscache_cookie
*cookie
)
202 return test_bit(FSCACHE_COOKIE_ENABLED
, &cookie
->flags
);
206 * slow-path functions for when there is actually caching available, and the
207 * netfs does actually have a valid token
208 * - these are not to be called directly
209 * - these are undefined symbols when FS-Cache is not configured and the
210 * optimiser takes care of not using them
212 extern int __fscache_register_netfs(struct fscache_netfs
*);
213 extern void __fscache_unregister_netfs(struct fscache_netfs
*);
214 extern struct fscache_cache_tag
*__fscache_lookup_cache_tag(const char *);
215 extern void __fscache_release_cache_tag(struct fscache_cache_tag
*);
217 extern struct fscache_cookie
*__fscache_acquire_cookie(
218 struct fscache_cookie
*,
219 const struct fscache_cookie_def
*,
221 extern void __fscache_relinquish_cookie(struct fscache_cookie
*, bool);
222 extern int __fscache_check_consistency(struct fscache_cookie
*);
223 extern void __fscache_update_cookie(struct fscache_cookie
*);
224 extern int __fscache_attr_changed(struct fscache_cookie
*);
225 extern void __fscache_invalidate(struct fscache_cookie
*);
226 extern void __fscache_wait_on_invalidate(struct fscache_cookie
*);
227 extern int __fscache_read_or_alloc_page(struct fscache_cookie
*,
229 fscache_rw_complete_t
,
232 extern int __fscache_read_or_alloc_pages(struct fscache_cookie
*,
233 struct address_space
*,
236 fscache_rw_complete_t
,
239 extern int __fscache_alloc_page(struct fscache_cookie
*, struct page
*, gfp_t
);
240 extern int __fscache_write_page(struct fscache_cookie
*, struct page
*, gfp_t
);
241 extern void __fscache_uncache_page(struct fscache_cookie
*, struct page
*);
242 extern bool __fscache_check_page_write(struct fscache_cookie
*, struct page
*);
243 extern void __fscache_wait_on_page_write(struct fscache_cookie
*, struct page
*);
244 extern bool __fscache_maybe_release_page(struct fscache_cookie
*, struct page
*,
246 extern void __fscache_uncache_all_inode_pages(struct fscache_cookie
*,
248 extern void __fscache_readpages_cancel(struct fscache_cookie
*cookie
,
249 struct list_head
*pages
);
250 extern void __fscache_disable_cookie(struct fscache_cookie
*, bool);
251 extern void __fscache_enable_cookie(struct fscache_cookie
*,
252 bool (*)(void *), void *);
255 * fscache_register_netfs - Register a filesystem as desiring caching services
256 * @netfs: The description of the filesystem
258 * Register a filesystem as desiring caching services if they're available.
260 * See Documentation/filesystems/caching/netfs-api.txt for a complete
264 int fscache_register_netfs(struct fscache_netfs
*netfs
)
266 if (fscache_available())
267 return __fscache_register_netfs(netfs
);
273 * fscache_unregister_netfs - Indicate that a filesystem no longer desires
275 * @netfs: The description of the filesystem
277 * Indicate that a filesystem no longer desires caching services for the
280 * See Documentation/filesystems/caching/netfs-api.txt for a complete
284 void fscache_unregister_netfs(struct fscache_netfs
*netfs
)
286 if (fscache_available())
287 __fscache_unregister_netfs(netfs
);
291 * fscache_lookup_cache_tag - Look up a cache tag
292 * @name: The name of the tag to search for
294 * Acquire a specific cache referral tag that can be used to select a specific
295 * cache in which to cache an index.
297 * See Documentation/filesystems/caching/netfs-api.txt for a complete
301 struct fscache_cache_tag
*fscache_lookup_cache_tag(const char *name
)
303 if (fscache_available())
304 return __fscache_lookup_cache_tag(name
);
310 * fscache_release_cache_tag - Release a cache tag
311 * @tag: The tag to release
313 * Release a reference to a cache referral tag previously looked up.
315 * See Documentation/filesystems/caching/netfs-api.txt for a complete
319 void fscache_release_cache_tag(struct fscache_cache_tag
*tag
)
321 if (fscache_available())
322 __fscache_release_cache_tag(tag
);
326 * fscache_acquire_cookie - Acquire a cookie to represent a cache object
327 * @parent: The cookie that's to be the parent of this one
328 * @def: A description of the cache object, including callback operations
329 * @netfs_data: An arbitrary piece of data to be kept in the cookie to
330 * represent the cache object to the netfs
331 * @enable: Whether or not to enable a data cookie immediately
333 * This function is used to inform FS-Cache about part of an index hierarchy
334 * that can be used to locate files. This is done by requesting a cookie for
335 * each index in the path to the file.
337 * See Documentation/filesystems/caching/netfs-api.txt for a complete
341 struct fscache_cookie
*fscache_acquire_cookie(
342 struct fscache_cookie
*parent
,
343 const struct fscache_cookie_def
*def
,
347 if (fscache_cookie_valid(parent
) && fscache_cookie_enabled(parent
))
348 return __fscache_acquire_cookie(parent
, def
, netfs_data
,
355 * fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding
357 * @cookie: The cookie being returned
358 * @retire: True if the cache object the cookie represents is to be discarded
360 * This function returns a cookie to the cache, forcibly discarding the
361 * associated cache object if retire is set to true.
363 * See Documentation/filesystems/caching/netfs-api.txt for a complete
367 void fscache_relinquish_cookie(struct fscache_cookie
*cookie
, bool retire
)
369 if (fscache_cookie_valid(cookie
))
370 __fscache_relinquish_cookie(cookie
, retire
);
374 * fscache_check_consistency - Request that if the cache is updated
375 * @cookie: The cookie representing the cache object
377 * Request an consistency check from fscache, which passes the request
378 * to the backing cache.
380 * Returns 0 if consistent and -ESTALE if inconsistent. May also
381 * return -ENOMEM and -ERESTARTSYS.
384 int fscache_check_consistency(struct fscache_cookie
*cookie
)
386 if (fscache_cookie_valid(cookie
) && fscache_cookie_enabled(cookie
))
387 return __fscache_check_consistency(cookie
);
393 * fscache_update_cookie - Request that a cache object be updated
394 * @cookie: The cookie representing the cache object
396 * Request an update of the index data for the cache object associated with the
399 * See Documentation/filesystems/caching/netfs-api.txt for a complete
403 void fscache_update_cookie(struct fscache_cookie
*cookie
)
405 if (fscache_cookie_valid(cookie
) && fscache_cookie_enabled(cookie
))
406 __fscache_update_cookie(cookie
);
410 * fscache_pin_cookie - Pin a data-storage cache object in its cache
411 * @cookie: The cookie representing the cache object
413 * Permit data-storage cache objects to be pinned in the cache.
415 * See Documentation/filesystems/caching/netfs-api.txt for a complete
419 int fscache_pin_cookie(struct fscache_cookie
*cookie
)
425 * fscache_pin_cookie - Unpin a data-storage cache object in its cache
426 * @cookie: The cookie representing the cache object
428 * Permit data-storage cache objects to be unpinned from the cache.
430 * See Documentation/filesystems/caching/netfs-api.txt for a complete
434 void fscache_unpin_cookie(struct fscache_cookie
*cookie
)
439 * fscache_attr_changed - Notify cache that an object's attributes changed
440 * @cookie: The cookie representing the cache object
442 * Send a notification to the cache indicating that an object's attributes have
443 * changed. This includes the data size. These attributes will be obtained
444 * through the get_attr() cookie definition op.
446 * See Documentation/filesystems/caching/netfs-api.txt for a complete
450 int fscache_attr_changed(struct fscache_cookie
*cookie
)
452 if (fscache_cookie_valid(cookie
) && fscache_cookie_enabled(cookie
))
453 return __fscache_attr_changed(cookie
);
459 * fscache_invalidate - Notify cache that an object needs invalidation
460 * @cookie: The cookie representing the cache object
462 * Notify the cache that an object is needs to be invalidated and that it
463 * should abort any retrievals or stores it is doing on the cache. The object
464 * is then marked non-caching until such time as the invalidation is complete.
466 * This can be called with spinlocks held.
468 * See Documentation/filesystems/caching/netfs-api.txt for a complete
472 void fscache_invalidate(struct fscache_cookie
*cookie
)
474 if (fscache_cookie_valid(cookie
) && fscache_cookie_enabled(cookie
))
475 __fscache_invalidate(cookie
);
479 * fscache_wait_on_invalidate - Wait for invalidation to complete
480 * @cookie: The cookie representing the cache object
482 * Wait for the invalidation of an object to complete.
484 * See Documentation/filesystems/caching/netfs-api.txt for a complete
488 void fscache_wait_on_invalidate(struct fscache_cookie
*cookie
)
490 if (fscache_cookie_valid(cookie
))
491 __fscache_wait_on_invalidate(cookie
);
495 * fscache_reserve_space - Reserve data space for a cached object
496 * @cookie: The cookie representing the cache object
497 * @i_size: The amount of space to be reserved
499 * Reserve an amount of space in the cache for the cache object attached to a
500 * cookie so that a write to that object within the space can always be
503 * See Documentation/filesystems/caching/netfs-api.txt for a complete
507 int fscache_reserve_space(struct fscache_cookie
*cookie
, loff_t size
)
513 * fscache_read_or_alloc_page - Read a page from the cache or allocate a block
514 * in which to store it
515 * @cookie: The cookie representing the cache object
516 * @page: The netfs page to fill if possible
517 * @end_io_func: The callback to invoke when and if the page is filled
518 * @context: An arbitrary piece of data to pass on to end_io_func()
519 * @gfp: The conditions under which memory allocation should be made
521 * Read a page from the cache, or if that's not possible make a potential
522 * one-block reservation in the cache into which the page may be stored once
523 * fetched from the server.
525 * If the page is not backed by the cache object, or if it there's some reason
526 * it can't be, -ENOBUFS will be returned and nothing more will be done for
529 * Else, if that page is backed by the cache, a read will be initiated directly
530 * to the netfs's page and 0 will be returned by this function. The
531 * end_io_func() callback will be invoked when the operation terminates on a
532 * completion or failure. Note that the callback may be invoked before the
535 * Else, if the page is unbacked, -ENODATA is returned and a block may have
536 * been allocated in the cache.
538 * See Documentation/filesystems/caching/netfs-api.txt for a complete
542 int fscache_read_or_alloc_page(struct fscache_cookie
*cookie
,
544 fscache_rw_complete_t end_io_func
,
548 if (fscache_cookie_valid(cookie
) && fscache_cookie_enabled(cookie
))
549 return __fscache_read_or_alloc_page(cookie
, page
, end_io_func
,
556 * fscache_read_or_alloc_pages - Read pages from the cache and/or allocate
557 * blocks in which to store them
558 * @cookie: The cookie representing the cache object
559 * @mapping: The netfs inode mapping to which the pages will be attached
560 * @pages: A list of potential netfs pages to be filled
561 * @nr_pages: Number of pages to be read and/or allocated
562 * @end_io_func: The callback to invoke when and if each page is filled
563 * @context: An arbitrary piece of data to pass on to end_io_func()
564 * @gfp: The conditions under which memory allocation should be made
566 * Read a set of pages from the cache, or if that's not possible, attempt to
567 * make a potential one-block reservation for each page in the cache into which
568 * that page may be stored once fetched from the server.
570 * If some pages are not backed by the cache object, or if it there's some
571 * reason they can't be, -ENOBUFS will be returned and nothing more will be
572 * done for that pages.
574 * Else, if some of the pages are backed by the cache, a read will be initiated
575 * directly to the netfs's page and 0 will be returned by this function. The
576 * end_io_func() callback will be invoked when the operation terminates on a
577 * completion or failure. Note that the callback may be invoked before the
580 * Else, if a page is unbacked, -ENODATA is returned and a block may have
581 * been allocated in the cache.
583 * Because the function may want to return all of -ENOBUFS, -ENODATA and 0 in
584 * regard to different pages, the return values are prioritised in that order.
585 * Any pages submitted for reading are removed from the pages list.
587 * See Documentation/filesystems/caching/netfs-api.txt for a complete
591 int fscache_read_or_alloc_pages(struct fscache_cookie
*cookie
,
592 struct address_space
*mapping
,
593 struct list_head
*pages
,
595 fscache_rw_complete_t end_io_func
,
599 if (fscache_cookie_valid(cookie
) && fscache_cookie_enabled(cookie
))
600 return __fscache_read_or_alloc_pages(cookie
, mapping
, pages
,
601 nr_pages
, end_io_func
,
608 * fscache_alloc_page - Allocate a block in which to store a page
609 * @cookie: The cookie representing the cache object
610 * @page: The netfs page to allocate a page for
611 * @gfp: The conditions under which memory allocation should be made
613 * Request Allocation a block in the cache in which to store a netfs page
614 * without retrieving any contents from the cache.
616 * If the page is not backed by a file then -ENOBUFS will be returned and
617 * nothing more will be done, and no reservation will be made.
619 * Else, a block will be allocated if one wasn't already, and 0 will be
622 * See Documentation/filesystems/caching/netfs-api.txt for a complete
626 int fscache_alloc_page(struct fscache_cookie
*cookie
,
630 if (fscache_cookie_valid(cookie
) && fscache_cookie_enabled(cookie
))
631 return __fscache_alloc_page(cookie
, page
, gfp
);
637 * fscache_readpages_cancel - Cancel read/alloc on pages
638 * @cookie: The cookie representing the inode's cache object.
639 * @pages: The netfs pages that we canceled write on in readpages()
641 * Uncache/unreserve the pages reserved earlier in readpages() via
642 * fscache_readpages_or_alloc() and similar. In most successful caches in
643 * readpages() this doesn't do anything. In cases when the underlying netfs's
644 * readahead failed we need to clean up the pagelist (unmark and uncache).
646 * This function may sleep as it may have to clean up disk state.
649 void fscache_readpages_cancel(struct fscache_cookie
*cookie
,
650 struct list_head
*pages
)
652 if (fscache_cookie_valid(cookie
))
653 __fscache_readpages_cancel(cookie
, pages
);
657 * fscache_write_page - Request storage of a page in the cache
658 * @cookie: The cookie representing the cache object
659 * @page: The netfs page to store
660 * @gfp: The conditions under which memory allocation should be made
662 * Request the contents of the netfs page be written into the cache. This
663 * request may be ignored if no cache block is currently allocated, in which
664 * case it will return -ENOBUFS.
666 * If a cache block was already allocated, a write will be initiated and 0 will
667 * be returned. The PG_fscache_write page bit is set immediately and will then
668 * be cleared at the completion of the write to indicate the success or failure
669 * of the operation. Note that the completion may happen before the return.
671 * See Documentation/filesystems/caching/netfs-api.txt for a complete
675 int fscache_write_page(struct fscache_cookie
*cookie
,
679 if (fscache_cookie_valid(cookie
) && fscache_cookie_enabled(cookie
))
680 return __fscache_write_page(cookie
, page
, gfp
);
686 * fscache_uncache_page - Indicate that caching is no longer required on a page
687 * @cookie: The cookie representing the cache object
688 * @page: The netfs page that was being cached.
690 * Tell the cache that we no longer want a page to be cached and that it should
691 * remove any knowledge of the netfs page it may have.
693 * Note that this cannot cancel any outstanding I/O operations between this
694 * page and the cache.
696 * See Documentation/filesystems/caching/netfs-api.txt for a complete
700 void fscache_uncache_page(struct fscache_cookie
*cookie
,
703 if (fscache_cookie_valid(cookie
))
704 __fscache_uncache_page(cookie
, page
);
708 * fscache_check_page_write - Ask if a page is being writing to the cache
709 * @cookie: The cookie representing the cache object
710 * @page: The netfs page that is being cached.
712 * Ask the cache if a page is being written to the cache.
714 * See Documentation/filesystems/caching/netfs-api.txt for a complete
718 bool fscache_check_page_write(struct fscache_cookie
*cookie
,
721 if (fscache_cookie_valid(cookie
))
722 return __fscache_check_page_write(cookie
, page
);
727 * fscache_wait_on_page_write - Wait for a page to complete writing to the cache
728 * @cookie: The cookie representing the cache object
729 * @page: The netfs page that is being cached.
731 * Ask the cache to wake us up when a page is no longer being written to the
734 * See Documentation/filesystems/caching/netfs-api.txt for a complete
738 void fscache_wait_on_page_write(struct fscache_cookie
*cookie
,
741 if (fscache_cookie_valid(cookie
))
742 __fscache_wait_on_page_write(cookie
, page
);
746 * fscache_maybe_release_page - Consider releasing a page, cancelling a store
747 * @cookie: The cookie representing the cache object
748 * @page: The netfs page that is being cached.
749 * @gfp: The gfp flags passed to releasepage()
751 * Consider releasing a page for the vmscan algorithm, on behalf of the netfs's
752 * releasepage() call. A storage request on the page may cancelled if it is
753 * not currently being processed.
755 * The function returns true if the page no longer has a storage request on it,
756 * and false if a storage request is left in place. If true is returned, the
757 * page will have been passed to fscache_uncache_page(). If false is returned
758 * the page cannot be freed yet.
761 bool fscache_maybe_release_page(struct fscache_cookie
*cookie
,
765 if (fscache_cookie_valid(cookie
) && PageFsCache(page
))
766 return __fscache_maybe_release_page(cookie
, page
, gfp
);
771 * fscache_uncache_all_inode_pages - Uncache all an inode's pages
772 * @cookie: The cookie representing the inode's cache object.
773 * @inode: The inode to uncache pages from.
775 * Uncache all the pages in an inode that are marked PG_fscache, assuming them
776 * to be associated with the given cookie.
778 * This function may sleep. It will wait for pages that are being written out
779 * and will wait whilst the PG_fscache mark is removed by the cache.
782 void fscache_uncache_all_inode_pages(struct fscache_cookie
*cookie
,
785 if (fscache_cookie_valid(cookie
))
786 __fscache_uncache_all_inode_pages(cookie
, inode
);
790 * fscache_disable_cookie - Disable a cookie
791 * @cookie: The cookie representing the cache object
792 * @invalidate: Invalidate the backing object
794 * Disable a cookie from accepting further alloc, read, write, invalidate,
795 * update or acquire operations. Outstanding operations can still be waited
796 * upon and pages can still be uncached and the cookie relinquished.
798 * This will not return until all outstanding operations have completed.
800 * If @invalidate is set, then the backing object will be invalidated and
801 * detached, otherwise it will just be detached.
804 void fscache_disable_cookie(struct fscache_cookie
*cookie
, bool invalidate
)
806 if (fscache_cookie_valid(cookie
) && fscache_cookie_enabled(cookie
))
807 __fscache_disable_cookie(cookie
, invalidate
);
811 * fscache_enable_cookie - Reenable a cookie
812 * @cookie: The cookie representing the cache object
813 * @can_enable: A function to permit enablement once lock is held
814 * @data: Data for can_enable()
816 * Reenable a previously disabled cookie, allowing it to accept further alloc,
817 * read, write, invalidate, update or acquire operations. An attempt will be
818 * made to immediately reattach the cookie to a backing object.
820 * The can_enable() function is called (if not NULL) once the enablement lock
821 * is held to rule on whether enablement is still permitted to go ahead.
824 void fscache_enable_cookie(struct fscache_cookie
*cookie
,
825 bool (*can_enable
)(void *data
),
828 if (fscache_cookie_valid(cookie
) && !fscache_cookie_enabled(cookie
))
829 __fscache_enable_cookie(cookie
, can_enable
, data
);
832 #endif /* _LINUX_FSCACHE_H */