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1 /* General filesystem caching interface
2 *
3 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
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.
10 *
11 * NOTE!!! See:
12 *
13 * Documentation/filesystems/caching/netfs-api.txt
14 *
15 * for a description of the network filesystem interface declared here.
16 */
17
18 #ifndef _LINUX_FSCACHE_H
19 #define _LINUX_FSCACHE_H
20
21 #include <linux/fs.h>
22 #include <linux/list.h>
23 #include <linux/pagemap.h>
24 #include <linux/pagevec.h>
25
26 #if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
27 #define fscache_available() (1)
28 #define fscache_cookie_valid(cookie) (cookie)
29 #else
30 #define fscache_available() (0)
31 #define fscache_cookie_valid(cookie) (0)
32 #endif
33
34
35 /*
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
38 */
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))
44
45 /* pattern used to fill dead space in an index entry */
46 #define FSCACHE_INDEX_DEADFILL_PATTERN 0x79
47
48 struct pagevec;
49 struct fscache_cache_tag;
50 struct fscache_cookie;
51 struct fscache_netfs;
52
53 typedef void (*fscache_rw_complete_t)(struct page *page,
54 void *context,
55 int error);
56
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 */
62 };
63
64 /*
65 * fscache cookie definition
66 */
67 struct fscache_cookie_def {
68 /* name of cookie type */
69 char name[16];
70
71 /* cookie type */
72 uint8_t type;
73 #define FSCACHE_COOKIE_TYPE_INDEX 0
74 #define FSCACHE_COOKIE_TYPE_DATAFILE 1
75
76 /* select the cache into which to insert an entry in this index
77 * - optional
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
81 */
82 struct fscache_cache_tag *(*select_cache)(
83 const void *parent_netfs_data,
84 const void *cookie_netfs_data);
85
86 /* get an index key
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
91 * presented
92 */
93 uint16_t (*get_key)(const void *cookie_netfs_data,
94 void *buffer,
95 uint16_t bufmax);
96
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
101 * presented
102 */
103 void (*get_attr)(const void *cookie_netfs_data, uint64_t *size);
104
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
111 * presented
112 */
113 uint16_t (*get_aux)(const void *cookie_netfs_data,
114 void *buffer,
115 uint16_t bufmax);
116
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
121 */
122 enum fscache_checkaux (*check_aux)(void *cookie_netfs_data,
123 const void *data,
124 uint16_t datalen);
125
126 /* get an extra reference on a read context
127 * - this function can be absent if the completion function doesn't
128 * require a context
129 */
130 void (*get_context)(void *cookie_netfs_data, void *context);
131
132 /* release an extra reference on a read context
133 * - this function can be absent if the completion function doesn't
134 * require a context
135 */
136 void (*put_context)(void *cookie_netfs_data, void *context);
137
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
142 */
143 void (*mark_page_cached)(void *cookie_netfs_data,
144 struct address_space *mapping,
145 struct page *page);
146
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
151 * cached pages
152 * - this is mandatory for any object that may have data
153 */
154 void (*now_uncached)(void *cookie_netfs_data);
155 };
156
157 /*
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
161 */
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 */
167 };
168
169 /*
170 * slow-path functions for when there is actually caching available, and the
171 * netfs does actually have a valid token
172 * - these are not to be called directly
173 * - these are undefined symbols when FS-Cache is not configured and the
174 * optimiser takes care of not using them
175 */
176 extern int __fscache_register_netfs(struct fscache_netfs *);
177 extern void __fscache_unregister_netfs(struct fscache_netfs *);
178 extern struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *);
179 extern void __fscache_release_cache_tag(struct fscache_cache_tag *);
180
181 extern struct fscache_cookie *__fscache_acquire_cookie(
182 struct fscache_cookie *,
183 const struct fscache_cookie_def *,
184 void *);
185 extern void __fscache_relinquish_cookie(struct fscache_cookie *, int);
186 extern int __fscache_check_consistency(struct fscache_cookie *);
187 extern void __fscache_update_cookie(struct fscache_cookie *);
188 extern int __fscache_attr_changed(struct fscache_cookie *);
189 extern void __fscache_invalidate(struct fscache_cookie *);
190 extern void __fscache_wait_on_invalidate(struct fscache_cookie *);
191 extern int __fscache_read_or_alloc_page(struct fscache_cookie *,
192 struct page *,
193 fscache_rw_complete_t,
194 void *,
195 gfp_t);
196 extern int __fscache_read_or_alloc_pages(struct fscache_cookie *,
197 struct address_space *,
198 struct list_head *,
199 unsigned *,
200 fscache_rw_complete_t,
201 void *,
202 gfp_t);
203 extern int __fscache_alloc_page(struct fscache_cookie *, struct page *, gfp_t);
204 extern int __fscache_write_page(struct fscache_cookie *, struct page *, gfp_t);
205 extern void __fscache_uncache_page(struct fscache_cookie *, struct page *);
206 extern bool __fscache_check_page_write(struct fscache_cookie *, struct page *);
207 extern void __fscache_wait_on_page_write(struct fscache_cookie *, struct page *);
208 extern bool __fscache_maybe_release_page(struct fscache_cookie *, struct page *,
209 gfp_t);
210 extern void __fscache_uncache_all_inode_pages(struct fscache_cookie *,
211 struct inode *);
212 extern void __fscache_readpages_cancel(struct fscache_cookie *cookie,
213 struct list_head *pages);
214
215 /**
216 * fscache_register_netfs - Register a filesystem as desiring caching services
217 * @netfs: The description of the filesystem
218 *
219 * Register a filesystem as desiring caching services if they're available.
220 *
221 * See Documentation/filesystems/caching/netfs-api.txt for a complete
222 * description.
223 */
224 static inline
225 int fscache_register_netfs(struct fscache_netfs *netfs)
226 {
227 if (fscache_available())
228 return __fscache_register_netfs(netfs);
229 else
230 return 0;
231 }
232
233 /**
234 * fscache_unregister_netfs - Indicate that a filesystem no longer desires
235 * caching services
236 * @netfs: The description of the filesystem
237 *
238 * Indicate that a filesystem no longer desires caching services for the
239 * moment.
240 *
241 * See Documentation/filesystems/caching/netfs-api.txt for a complete
242 * description.
243 */
244 static inline
245 void fscache_unregister_netfs(struct fscache_netfs *netfs)
246 {
247 if (fscache_available())
248 __fscache_unregister_netfs(netfs);
249 }
250
251 /**
252 * fscache_lookup_cache_tag - Look up a cache tag
253 * @name: The name of the tag to search for
254 *
255 * Acquire a specific cache referral tag that can be used to select a specific
256 * cache in which to cache an index.
257 *
258 * See Documentation/filesystems/caching/netfs-api.txt for a complete
259 * description.
260 */
261 static inline
262 struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name)
263 {
264 if (fscache_available())
265 return __fscache_lookup_cache_tag(name);
266 else
267 return NULL;
268 }
269
270 /**
271 * fscache_release_cache_tag - Release a cache tag
272 * @tag: The tag to release
273 *
274 * Release a reference to a cache referral tag previously looked up.
275 *
276 * See Documentation/filesystems/caching/netfs-api.txt for a complete
277 * description.
278 */
279 static inline
280 void fscache_release_cache_tag(struct fscache_cache_tag *tag)
281 {
282 if (fscache_available())
283 __fscache_release_cache_tag(tag);
284 }
285
286 /**
287 * fscache_acquire_cookie - Acquire a cookie to represent a cache object
288 * @parent: The cookie that's to be the parent of this one
289 * @def: A description of the cache object, including callback operations
290 * @netfs_data: An arbitrary piece of data to be kept in the cookie to
291 * represent the cache object to the netfs
292 *
293 * This function is used to inform FS-Cache about part of an index hierarchy
294 * that can be used to locate files. This is done by requesting a cookie for
295 * each index in the path to the file.
296 *
297 * See Documentation/filesystems/caching/netfs-api.txt for a complete
298 * description.
299 */
300 static inline
301 struct fscache_cookie *fscache_acquire_cookie(
302 struct fscache_cookie *parent,
303 const struct fscache_cookie_def *def,
304 void *netfs_data)
305 {
306 if (fscache_cookie_valid(parent))
307 return __fscache_acquire_cookie(parent, def, netfs_data);
308 else
309 return NULL;
310 }
311
312 /**
313 * fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding
314 * it
315 * @cookie: The cookie being returned
316 * @retire: True if the cache object the cookie represents is to be discarded
317 *
318 * This function returns a cookie to the cache, forcibly discarding the
319 * associated cache object if retire is set to true.
320 *
321 * See Documentation/filesystems/caching/netfs-api.txt for a complete
322 * description.
323 */
324 static inline
325 void fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
326 {
327 if (fscache_cookie_valid(cookie))
328 __fscache_relinquish_cookie(cookie, retire);
329 }
330
331 /**
332 * fscache_check_consistency - Request that if the cache is updated
333 * @cookie: The cookie representing the cache object
334 *
335 * Request an consistency check from fscache, which passes the request
336 * to the backing cache.
337 *
338 * Returns 0 if consistent and -ESTALE if inconsistent. May also
339 * return -ENOMEM and -ERESTARTSYS.
340 */
341 static inline
342 int fscache_check_consistency(struct fscache_cookie *cookie)
343 {
344 if (fscache_cookie_valid(cookie))
345 return __fscache_check_consistency(cookie);
346 else
347 return 0;
348 }
349
350 /**
351 * fscache_update_cookie - Request that a cache object be updated
352 * @cookie: The cookie representing the cache object
353 *
354 * Request an update of the index data for the cache object associated with the
355 * cookie.
356 *
357 * See Documentation/filesystems/caching/netfs-api.txt for a complete
358 * description.
359 */
360 static inline
361 void fscache_update_cookie(struct fscache_cookie *cookie)
362 {
363 if (fscache_cookie_valid(cookie))
364 __fscache_update_cookie(cookie);
365 }
366
367 /**
368 * fscache_pin_cookie - Pin a data-storage cache object in its cache
369 * @cookie: The cookie representing the cache object
370 *
371 * Permit data-storage cache objects to be pinned in the cache.
372 *
373 * See Documentation/filesystems/caching/netfs-api.txt for a complete
374 * description.
375 */
376 static inline
377 int fscache_pin_cookie(struct fscache_cookie *cookie)
378 {
379 return -ENOBUFS;
380 }
381
382 /**
383 * fscache_pin_cookie - Unpin a data-storage cache object in its cache
384 * @cookie: The cookie representing the cache object
385 *
386 * Permit data-storage cache objects to be unpinned from the cache.
387 *
388 * See Documentation/filesystems/caching/netfs-api.txt for a complete
389 * description.
390 */
391 static inline
392 void fscache_unpin_cookie(struct fscache_cookie *cookie)
393 {
394 }
395
396 /**
397 * fscache_attr_changed - Notify cache that an object's attributes changed
398 * @cookie: The cookie representing the cache object
399 *
400 * Send a notification to the cache indicating that an object's attributes have
401 * changed. This includes the data size. These attributes will be obtained
402 * through the get_attr() cookie definition op.
403 *
404 * See Documentation/filesystems/caching/netfs-api.txt for a complete
405 * description.
406 */
407 static inline
408 int fscache_attr_changed(struct fscache_cookie *cookie)
409 {
410 if (fscache_cookie_valid(cookie))
411 return __fscache_attr_changed(cookie);
412 else
413 return -ENOBUFS;
414 }
415
416 /**
417 * fscache_invalidate - Notify cache that an object needs invalidation
418 * @cookie: The cookie representing the cache object
419 *
420 * Notify the cache that an object is needs to be invalidated and that it
421 * should abort any retrievals or stores it is doing on the cache. The object
422 * is then marked non-caching until such time as the invalidation is complete.
423 *
424 * This can be called with spinlocks held.
425 *
426 * See Documentation/filesystems/caching/netfs-api.txt for a complete
427 * description.
428 */
429 static inline
430 void fscache_invalidate(struct fscache_cookie *cookie)
431 {
432 if (fscache_cookie_valid(cookie))
433 __fscache_invalidate(cookie);
434 }
435
436 /**
437 * fscache_wait_on_invalidate - Wait for invalidation to complete
438 * @cookie: The cookie representing the cache object
439 *
440 * Wait for the invalidation of an object to complete.
441 *
442 * See Documentation/filesystems/caching/netfs-api.txt for a complete
443 * description.
444 */
445 static inline
446 void fscache_wait_on_invalidate(struct fscache_cookie *cookie)
447 {
448 if (fscache_cookie_valid(cookie))
449 __fscache_wait_on_invalidate(cookie);
450 }
451
452 /**
453 * fscache_reserve_space - Reserve data space for a cached object
454 * @cookie: The cookie representing the cache object
455 * @i_size: The amount of space to be reserved
456 *
457 * Reserve an amount of space in the cache for the cache object attached to a
458 * cookie so that a write to that object within the space can always be
459 * honoured.
460 *
461 * See Documentation/filesystems/caching/netfs-api.txt for a complete
462 * description.
463 */
464 static inline
465 int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size)
466 {
467 return -ENOBUFS;
468 }
469
470 /**
471 * fscache_read_or_alloc_page - Read a page from the cache or allocate a block
472 * in which to store it
473 * @cookie: The cookie representing the cache object
474 * @page: The netfs page to fill if possible
475 * @end_io_func: The callback to invoke when and if the page is filled
476 * @context: An arbitrary piece of data to pass on to end_io_func()
477 * @gfp: The conditions under which memory allocation should be made
478 *
479 * Read a page from the cache, or if that's not possible make a potential
480 * one-block reservation in the cache into which the page may be stored once
481 * fetched from the server.
482 *
483 * If the page is not backed by the cache object, or if it there's some reason
484 * it can't be, -ENOBUFS will be returned and nothing more will be done for
485 * that page.
486 *
487 * Else, if that page is backed by the cache, a read will be initiated directly
488 * to the netfs's page and 0 will be returned by this function. The
489 * end_io_func() callback will be invoked when the operation terminates on a
490 * completion or failure. Note that the callback may be invoked before the
491 * return.
492 *
493 * Else, if the page is unbacked, -ENODATA is returned and a block may have
494 * been allocated in the cache.
495 *
496 * See Documentation/filesystems/caching/netfs-api.txt for a complete
497 * description.
498 */
499 static inline
500 int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
501 struct page *page,
502 fscache_rw_complete_t end_io_func,
503 void *context,
504 gfp_t gfp)
505 {
506 if (fscache_cookie_valid(cookie))
507 return __fscache_read_or_alloc_page(cookie, page, end_io_func,
508 context, gfp);
509 else
510 return -ENOBUFS;
511 }
512
513 /**
514 * fscache_read_or_alloc_pages - Read pages from the cache and/or allocate
515 * blocks in which to store them
516 * @cookie: The cookie representing the cache object
517 * @mapping: The netfs inode mapping to which the pages will be attached
518 * @pages: A list of potential netfs pages to be filled
519 * @nr_pages: Number of pages to be read and/or allocated
520 * @end_io_func: The callback to invoke when and if each page is filled
521 * @context: An arbitrary piece of data to pass on to end_io_func()
522 * @gfp: The conditions under which memory allocation should be made
523 *
524 * Read a set of pages from the cache, or if that's not possible, attempt to
525 * make a potential one-block reservation for each page in the cache into which
526 * that page may be stored once fetched from the server.
527 *
528 * If some pages are not backed by the cache object, or if it there's some
529 * reason they can't be, -ENOBUFS will be returned and nothing more will be
530 * done for that pages.
531 *
532 * Else, if some of the pages are backed by the cache, a read will be initiated
533 * directly to the netfs's page and 0 will be returned by this function. The
534 * end_io_func() callback will be invoked when the operation terminates on a
535 * completion or failure. Note that the callback may be invoked before the
536 * return.
537 *
538 * Else, if a page is unbacked, -ENODATA is returned and a block may have
539 * been allocated in the cache.
540 *
541 * Because the function may want to return all of -ENOBUFS, -ENODATA and 0 in
542 * regard to different pages, the return values are prioritised in that order.
543 * Any pages submitted for reading are removed from the pages list.
544 *
545 * See Documentation/filesystems/caching/netfs-api.txt for a complete
546 * description.
547 */
548 static inline
549 int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
550 struct address_space *mapping,
551 struct list_head *pages,
552 unsigned *nr_pages,
553 fscache_rw_complete_t end_io_func,
554 void *context,
555 gfp_t gfp)
556 {
557 if (fscache_cookie_valid(cookie))
558 return __fscache_read_or_alloc_pages(cookie, mapping, pages,
559 nr_pages, end_io_func,
560 context, gfp);
561 else
562 return -ENOBUFS;
563 }
564
565 /**
566 * fscache_alloc_page - Allocate a block in which to store a page
567 * @cookie: The cookie representing the cache object
568 * @page: The netfs page to allocate a page for
569 * @gfp: The conditions under which memory allocation should be made
570 *
571 * Request Allocation a block in the cache in which to store a netfs page
572 * without retrieving any contents from the cache.
573 *
574 * If the page is not backed by a file then -ENOBUFS will be returned and
575 * nothing more will be done, and no reservation will be made.
576 *
577 * Else, a block will be allocated if one wasn't already, and 0 will be
578 * returned
579 *
580 * See Documentation/filesystems/caching/netfs-api.txt for a complete
581 * description.
582 */
583 static inline
584 int fscache_alloc_page(struct fscache_cookie *cookie,
585 struct page *page,
586 gfp_t gfp)
587 {
588 if (fscache_cookie_valid(cookie))
589 return __fscache_alloc_page(cookie, page, gfp);
590 else
591 return -ENOBUFS;
592 }
593
594 /**
595 * fscache_readpages_cancel - Cancel read/alloc on pages
596 * @cookie: The cookie representing the inode's cache object.
597 * @pages: The netfs pages that we canceled write on in readpages()
598 *
599 * Uncache/unreserve the pages reserved earlier in readpages() via
600 * fscache_readpages_or_alloc() and similar. In most successful caches in
601 * readpages() this doesn't do anything. In cases when the underlying netfs's
602 * readahead failed we need to clean up the pagelist (unmark and uncache).
603 *
604 * This function may sleep as it may have to clean up disk state.
605 */
606 static inline
607 void fscache_readpages_cancel(struct fscache_cookie *cookie,
608 struct list_head *pages)
609 {
610 if (fscache_cookie_valid(cookie))
611 __fscache_readpages_cancel(cookie, pages);
612 }
613
614 /**
615 * fscache_write_page - Request storage of a page in the cache
616 * @cookie: The cookie representing the cache object
617 * @page: The netfs page to store
618 * @gfp: The conditions under which memory allocation should be made
619 *
620 * Request the contents of the netfs page be written into the cache. This
621 * request may be ignored if no cache block is currently allocated, in which
622 * case it will return -ENOBUFS.
623 *
624 * If a cache block was already allocated, a write will be initiated and 0 will
625 * be returned. The PG_fscache_write page bit is set immediately and will then
626 * be cleared at the completion of the write to indicate the success or failure
627 * of the operation. Note that the completion may happen before the return.
628 *
629 * See Documentation/filesystems/caching/netfs-api.txt for a complete
630 * description.
631 */
632 static inline
633 int fscache_write_page(struct fscache_cookie *cookie,
634 struct page *page,
635 gfp_t gfp)
636 {
637 if (fscache_cookie_valid(cookie))
638 return __fscache_write_page(cookie, page, gfp);
639 else
640 return -ENOBUFS;
641 }
642
643 /**
644 * fscache_uncache_page - Indicate that caching is no longer required on a page
645 * @cookie: The cookie representing the cache object
646 * @page: The netfs page that was being cached.
647 *
648 * Tell the cache that we no longer want a page to be cached and that it should
649 * remove any knowledge of the netfs page it may have.
650 *
651 * Note that this cannot cancel any outstanding I/O operations between this
652 * page and the cache.
653 *
654 * See Documentation/filesystems/caching/netfs-api.txt for a complete
655 * description.
656 */
657 static inline
658 void fscache_uncache_page(struct fscache_cookie *cookie,
659 struct page *page)
660 {
661 if (fscache_cookie_valid(cookie))
662 __fscache_uncache_page(cookie, page);
663 }
664
665 /**
666 * fscache_check_page_write - Ask if a page is being writing to the cache
667 * @cookie: The cookie representing the cache object
668 * @page: The netfs page that is being cached.
669 *
670 * Ask the cache if a page is being written to the cache.
671 *
672 * See Documentation/filesystems/caching/netfs-api.txt for a complete
673 * description.
674 */
675 static inline
676 bool fscache_check_page_write(struct fscache_cookie *cookie,
677 struct page *page)
678 {
679 if (fscache_cookie_valid(cookie))
680 return __fscache_check_page_write(cookie, page);
681 return false;
682 }
683
684 /**
685 * fscache_wait_on_page_write - Wait for a page to complete writing to the cache
686 * @cookie: The cookie representing the cache object
687 * @page: The netfs page that is being cached.
688 *
689 * Ask the cache to wake us up when a page is no longer being written to the
690 * cache.
691 *
692 * See Documentation/filesystems/caching/netfs-api.txt for a complete
693 * description.
694 */
695 static inline
696 void fscache_wait_on_page_write(struct fscache_cookie *cookie,
697 struct page *page)
698 {
699 if (fscache_cookie_valid(cookie))
700 __fscache_wait_on_page_write(cookie, page);
701 }
702
703 /**
704 * fscache_maybe_release_page - Consider releasing a page, cancelling a store
705 * @cookie: The cookie representing the cache object
706 * @page: The netfs page that is being cached.
707 * @gfp: The gfp flags passed to releasepage()
708 *
709 * Consider releasing a page for the vmscan algorithm, on behalf of the netfs's
710 * releasepage() call. A storage request on the page may cancelled if it is
711 * not currently being processed.
712 *
713 * The function returns true if the page no longer has a storage request on it,
714 * and false if a storage request is left in place. If true is returned, the
715 * page will have been passed to fscache_uncache_page(). If false is returned
716 * the page cannot be freed yet.
717 */
718 static inline
719 bool fscache_maybe_release_page(struct fscache_cookie *cookie,
720 struct page *page,
721 gfp_t gfp)
722 {
723 if (fscache_cookie_valid(cookie) && PageFsCache(page))
724 return __fscache_maybe_release_page(cookie, page, gfp);
725 return false;
726 }
727
728 /**
729 * fscache_uncache_all_inode_pages - Uncache all an inode's pages
730 * @cookie: The cookie representing the inode's cache object.
731 * @inode: The inode to uncache pages from.
732 *
733 * Uncache all the pages in an inode that are marked PG_fscache, assuming them
734 * to be associated with the given cookie.
735 *
736 * This function may sleep. It will wait for pages that are being written out
737 * and will wait whilst the PG_fscache mark is removed by the cache.
738 */
739 static inline
740 void fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
741 struct inode *inode)
742 {
743 if (fscache_cookie_valid(cookie))
744 __fscache_uncache_all_inode_pages(cookie, inode);
745 }
746
747 #endif /* _LINUX_FSCACHE_H */