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1 | /* General filesystem caching backing cache 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/backend-api.txt | |
14 | * | |
15 | * for a description of the cache backend interface declared here. | |
16 | */ | |
17 | ||
18 | #ifndef _LINUX_FSCACHE_CACHE_H | |
19 | #define _LINUX_FSCACHE_CACHE_H | |
20 | ||
21 | #include <linux/fscache.h> | |
22 | #include <linux/sched.h> | |
23 | #include <linux/workqueue.h> | |
24 | ||
25 | #define NR_MAXCACHES BITS_PER_LONG | |
26 | ||
27 | struct fscache_cache; | |
28 | struct fscache_cache_ops; | |
29 | struct fscache_object; | |
30 | struct fscache_operation; | |
31 | ||
32 | /* | |
33 | * cache tag definition | |
34 | */ | |
35 | struct fscache_cache_tag { | |
36 | struct list_head link; | |
37 | struct fscache_cache *cache; /* cache referred to by this tag */ | |
38 | unsigned long flags; | |
39 | #define FSCACHE_TAG_RESERVED 0 /* T if tag is reserved for a cache */ | |
40 | atomic_t usage; | |
41 | char name[0]; /* tag name */ | |
42 | }; | |
43 | ||
44 | /* | |
45 | * cache definition | |
46 | */ | |
47 | struct fscache_cache { | |
48 | const struct fscache_cache_ops *ops; | |
49 | struct fscache_cache_tag *tag; /* tag representing this cache */ | |
50 | struct kobject *kobj; /* system representation of this cache */ | |
51 | struct list_head link; /* link in list of caches */ | |
52 | size_t max_index_size; /* maximum size of index data */ | |
53 | char identifier[36]; /* cache label */ | |
54 | ||
55 | /* node management */ | |
56 | struct work_struct op_gc; /* operation garbage collector */ | |
57 | struct list_head object_list; /* list of data/index objects */ | |
58 | struct list_head op_gc_list; /* list of ops to be deleted */ | |
59 | spinlock_t object_list_lock; | |
60 | spinlock_t op_gc_list_lock; | |
61 | atomic_t object_count; /* no. of live objects in this cache */ | |
62 | struct fscache_object *fsdef; /* object for the fsdef index */ | |
63 | unsigned long flags; | |
64 | #define FSCACHE_IOERROR 0 /* cache stopped on I/O error */ | |
65 | #define FSCACHE_CACHE_WITHDRAWN 1 /* cache has been withdrawn */ | |
66 | }; | |
67 | ||
68 | extern wait_queue_head_t fscache_cache_cleared_wq; | |
69 | ||
70 | /* | |
71 | * operation to be applied to a cache object | |
72 | * - retrieval initiation operations are done in the context of the process | |
73 | * that issued them, and not in an async thread pool | |
74 | */ | |
75 | typedef void (*fscache_operation_release_t)(struct fscache_operation *op); | |
76 | typedef void (*fscache_operation_processor_t)(struct fscache_operation *op); | |
77 | ||
78 | enum fscache_operation_state { | |
79 | FSCACHE_OP_ST_BLANK, /* Op is not yet submitted */ | |
80 | FSCACHE_OP_ST_INITIALISED, /* Op is initialised */ | |
81 | FSCACHE_OP_ST_PENDING, /* Op is blocked from running */ | |
82 | FSCACHE_OP_ST_IN_PROGRESS, /* Op is in progress */ | |
83 | FSCACHE_OP_ST_COMPLETE, /* Op is complete */ | |
84 | FSCACHE_OP_ST_CANCELLED, /* Op has been cancelled */ | |
85 | FSCACHE_OP_ST_DEAD /* Op is now dead */ | |
86 | }; | |
87 | ||
88 | struct fscache_operation { | |
89 | struct work_struct work; /* record for async ops */ | |
90 | struct list_head pend_link; /* link in object->pending_ops */ | |
91 | struct fscache_object *object; /* object to be operated upon */ | |
92 | ||
93 | unsigned long flags; | |
94 | #define FSCACHE_OP_TYPE 0x000f /* operation type */ | |
95 | #define FSCACHE_OP_ASYNC 0x0001 /* - async op, processor may sleep for disk */ | |
96 | #define FSCACHE_OP_MYTHREAD 0x0002 /* - processing is done be issuing thread, not pool */ | |
97 | #define FSCACHE_OP_WAITING 4 /* cleared when op is woken */ | |
98 | #define FSCACHE_OP_EXCLUSIVE 5 /* exclusive op, other ops must wait */ | |
99 | #define FSCACHE_OP_DEC_READ_CNT 6 /* decrement object->n_reads on destruction */ | |
100 | #define FSCACHE_OP_UNUSE_COOKIE 7 /* call fscache_unuse_cookie() on completion */ | |
101 | #define FSCACHE_OP_KEEP_FLAGS 0x00f0 /* flags to keep when repurposing an op */ | |
102 | ||
103 | enum fscache_operation_state state; | |
104 | atomic_t usage; | |
105 | unsigned debug_id; /* debugging ID */ | |
106 | ||
107 | /* operation processor callback | |
108 | * - can be NULL if FSCACHE_OP_WAITING is going to be used to perform | |
109 | * the op in a non-pool thread */ | |
110 | fscache_operation_processor_t processor; | |
111 | ||
112 | /* operation releaser */ | |
113 | fscache_operation_release_t release; | |
114 | }; | |
115 | ||
116 | extern atomic_t fscache_op_debug_id; | |
117 | extern void fscache_op_work_func(struct work_struct *work); | |
118 | ||
119 | extern void fscache_enqueue_operation(struct fscache_operation *); | |
120 | extern void fscache_op_complete(struct fscache_operation *, bool); | |
121 | extern void fscache_put_operation(struct fscache_operation *); | |
122 | ||
123 | /** | |
124 | * fscache_operation_init - Do basic initialisation of an operation | |
125 | * @op: The operation to initialise | |
126 | * @release: The release function to assign | |
127 | * | |
128 | * Do basic initialisation of an operation. The caller must still set flags, | |
129 | * object and processor if needed. | |
130 | */ | |
131 | static inline void fscache_operation_init(struct fscache_operation *op, | |
132 | fscache_operation_processor_t processor, | |
133 | fscache_operation_release_t release) | |
134 | { | |
135 | INIT_WORK(&op->work, fscache_op_work_func); | |
136 | atomic_set(&op->usage, 1); | |
137 | op->state = FSCACHE_OP_ST_INITIALISED; | |
138 | op->debug_id = atomic_inc_return(&fscache_op_debug_id); | |
139 | op->processor = processor; | |
140 | op->release = release; | |
141 | INIT_LIST_HEAD(&op->pend_link); | |
142 | } | |
143 | ||
144 | /* | |
145 | * data read operation | |
146 | */ | |
147 | struct fscache_retrieval { | |
148 | struct fscache_operation op; | |
149 | struct address_space *mapping; /* netfs pages */ | |
150 | fscache_rw_complete_t end_io_func; /* function to call on I/O completion */ | |
151 | void *context; /* netfs read context (pinned) */ | |
152 | struct list_head to_do; /* list of things to be done by the backend */ | |
153 | unsigned long start_time; /* time at which retrieval started */ | |
154 | unsigned n_pages; /* number of pages to be retrieved */ | |
155 | }; | |
156 | ||
157 | typedef int (*fscache_page_retrieval_func_t)(struct fscache_retrieval *op, | |
158 | struct page *page, | |
159 | gfp_t gfp); | |
160 | ||
161 | typedef int (*fscache_pages_retrieval_func_t)(struct fscache_retrieval *op, | |
162 | struct list_head *pages, | |
163 | unsigned *nr_pages, | |
164 | gfp_t gfp); | |
165 | ||
166 | /** | |
167 | * fscache_get_retrieval - Get an extra reference on a retrieval operation | |
168 | * @op: The retrieval operation to get a reference on | |
169 | * | |
170 | * Get an extra reference on a retrieval operation. | |
171 | */ | |
172 | static inline | |
173 | struct fscache_retrieval *fscache_get_retrieval(struct fscache_retrieval *op) | |
174 | { | |
175 | atomic_inc(&op->op.usage); | |
176 | return op; | |
177 | } | |
178 | ||
179 | /** | |
180 | * fscache_enqueue_retrieval - Enqueue a retrieval operation for processing | |
181 | * @op: The retrieval operation affected | |
182 | * | |
183 | * Enqueue a retrieval operation for processing by the FS-Cache thread pool. | |
184 | */ | |
185 | static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op) | |
186 | { | |
187 | fscache_enqueue_operation(&op->op); | |
188 | } | |
189 | ||
190 | /** | |
191 | * fscache_retrieval_complete - Record (partial) completion of a retrieval | |
192 | * @op: The retrieval operation affected | |
193 | * @n_pages: The number of pages to account for | |
194 | */ | |
195 | static inline void fscache_retrieval_complete(struct fscache_retrieval *op, | |
196 | int n_pages) | |
197 | { | |
198 | op->n_pages -= n_pages; | |
199 | if (op->n_pages <= 0) | |
200 | fscache_op_complete(&op->op, true); | |
201 | } | |
202 | ||
203 | /** | |
204 | * fscache_put_retrieval - Drop a reference to a retrieval operation | |
205 | * @op: The retrieval operation affected | |
206 | * @n_pages: The number of pages to account for | |
207 | * | |
208 | * Drop a reference to a retrieval operation. | |
209 | */ | |
210 | static inline void fscache_put_retrieval(struct fscache_retrieval *op) | |
211 | { | |
212 | fscache_put_operation(&op->op); | |
213 | } | |
214 | ||
215 | /* | |
216 | * cached page storage work item | |
217 | * - used to do three things: | |
218 | * - batch writes to the cache | |
219 | * - do cache writes asynchronously | |
220 | * - defer writes until cache object lookup completion | |
221 | */ | |
222 | struct fscache_storage { | |
223 | struct fscache_operation op; | |
224 | pgoff_t store_limit; /* don't write more than this */ | |
225 | }; | |
226 | ||
227 | /* | |
228 | * cache operations | |
229 | */ | |
230 | struct fscache_cache_ops { | |
231 | /* name of cache provider */ | |
232 | const char *name; | |
233 | ||
234 | /* allocate an object record for a cookie */ | |
235 | struct fscache_object *(*alloc_object)(struct fscache_cache *cache, | |
236 | struct fscache_cookie *cookie); | |
237 | ||
238 | /* look up the object for a cookie | |
239 | * - return -ETIMEDOUT to be requeued | |
240 | */ | |
241 | int (*lookup_object)(struct fscache_object *object); | |
242 | ||
243 | /* finished looking up */ | |
244 | void (*lookup_complete)(struct fscache_object *object); | |
245 | ||
246 | /* increment the usage count on this object (may fail if unmounting) */ | |
247 | struct fscache_object *(*grab_object)(struct fscache_object *object); | |
248 | ||
249 | /* pin an object in the cache */ | |
250 | int (*pin_object)(struct fscache_object *object); | |
251 | ||
252 | /* unpin an object in the cache */ | |
253 | void (*unpin_object)(struct fscache_object *object); | |
254 | ||
255 | /* store the updated auxiliary data on an object */ | |
256 | void (*update_object)(struct fscache_object *object); | |
257 | ||
258 | /* Invalidate an object */ | |
259 | void (*invalidate_object)(struct fscache_operation *op); | |
260 | ||
261 | /* discard the resources pinned by an object and effect retirement if | |
262 | * necessary */ | |
263 | void (*drop_object)(struct fscache_object *object); | |
264 | ||
265 | /* dispose of a reference to an object */ | |
266 | void (*put_object)(struct fscache_object *object); | |
267 | ||
268 | /* sync a cache */ | |
269 | void (*sync_cache)(struct fscache_cache *cache); | |
270 | ||
271 | /* notification that the attributes of a non-index object (such as | |
272 | * i_size) have changed */ | |
273 | int (*attr_changed)(struct fscache_object *object); | |
274 | ||
275 | /* reserve space for an object's data and associated metadata */ | |
276 | int (*reserve_space)(struct fscache_object *object, loff_t i_size); | |
277 | ||
278 | /* request a backing block for a page be read or allocated in the | |
279 | * cache */ | |
280 | fscache_page_retrieval_func_t read_or_alloc_page; | |
281 | ||
282 | /* request backing blocks for a list of pages be read or allocated in | |
283 | * the cache */ | |
284 | fscache_pages_retrieval_func_t read_or_alloc_pages; | |
285 | ||
286 | /* request a backing block for a page be allocated in the cache so that | |
287 | * it can be written directly */ | |
288 | fscache_page_retrieval_func_t allocate_page; | |
289 | ||
290 | /* request backing blocks for pages be allocated in the cache so that | |
291 | * they can be written directly */ | |
292 | fscache_pages_retrieval_func_t allocate_pages; | |
293 | ||
294 | /* write a page to its backing block in the cache */ | |
295 | int (*write_page)(struct fscache_storage *op, struct page *page); | |
296 | ||
297 | /* detach backing block from a page (optional) | |
298 | * - must release the cookie lock before returning | |
299 | * - may sleep | |
300 | */ | |
301 | void (*uncache_page)(struct fscache_object *object, | |
302 | struct page *page); | |
303 | ||
304 | /* dissociate a cache from all the pages it was backing */ | |
305 | void (*dissociate_pages)(struct fscache_cache *cache); | |
306 | }; | |
307 | ||
308 | /* | |
309 | * data file or index object cookie | |
310 | * - a file will only appear in one cache | |
311 | * - a request to cache a file may or may not be honoured, subject to | |
312 | * constraints such as disk space | |
313 | * - indices are created on disk just-in-time | |
314 | */ | |
315 | struct fscache_cookie { | |
316 | atomic_t usage; /* number of users of this cookie */ | |
317 | atomic_t n_children; /* number of children of this cookie */ | |
318 | atomic_t n_active; /* number of active users of netfs ptrs */ | |
319 | spinlock_t lock; | |
320 | spinlock_t stores_lock; /* lock on page store tree */ | |
321 | struct hlist_head backing_objects; /* object(s) backing this file/index */ | |
322 | const struct fscache_cookie_def *def; /* definition */ | |
323 | struct fscache_cookie *parent; /* parent of this entry */ | |
324 | void *netfs_data; /* back pointer to netfs */ | |
325 | struct radix_tree_root stores; /* pages to be stored on this cookie */ | |
326 | #define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */ | |
327 | #define FSCACHE_COOKIE_STORING_TAG 1 /* pages tag: writing to cache */ | |
328 | ||
329 | unsigned long flags; | |
330 | #define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */ | |
331 | #define FSCACHE_COOKIE_NO_DATA_YET 1 /* T if new object with no cached data yet */ | |
332 | #define FSCACHE_COOKIE_UNAVAILABLE 2 /* T if cookie is unavailable (error, etc) */ | |
333 | #define FSCACHE_COOKIE_INVALIDATING 3 /* T if cookie is being invalidated */ | |
334 | #define FSCACHE_COOKIE_RELINQUISHED 4 /* T if cookie has been relinquished */ | |
335 | #define FSCACHE_COOKIE_RETIRED 5 /* T if cookie was retired */ | |
336 | }; | |
337 | ||
338 | extern struct fscache_cookie fscache_fsdef_index; | |
339 | ||
340 | /* | |
341 | * Event list for fscache_object::{event_mask,events} | |
342 | */ | |
343 | enum { | |
344 | FSCACHE_OBJECT_EV_NEW_CHILD, /* T if object has a new child */ | |
345 | FSCACHE_OBJECT_EV_PARENT_READY, /* T if object's parent is ready */ | |
346 | FSCACHE_OBJECT_EV_UPDATE, /* T if object should be updated */ | |
347 | FSCACHE_OBJECT_EV_INVALIDATE, /* T if cache requested object invalidation */ | |
348 | FSCACHE_OBJECT_EV_CLEARED, /* T if accessors all gone */ | |
349 | FSCACHE_OBJECT_EV_ERROR, /* T if fatal error occurred during processing */ | |
350 | FSCACHE_OBJECT_EV_KILL, /* T if netfs relinquished or cache withdrew object */ | |
351 | NR_FSCACHE_OBJECT_EVENTS | |
352 | }; | |
353 | ||
354 | #define FSCACHE_OBJECT_EVENTS_MASK ((1UL << NR_FSCACHE_OBJECT_EVENTS) - 1) | |
355 | ||
356 | /* | |
357 | * States for object state machine. | |
358 | */ | |
359 | struct fscache_transition { | |
360 | unsigned long events; | |
361 | const struct fscache_state *transit_to; | |
362 | }; | |
363 | ||
364 | struct fscache_state { | |
365 | char name[24]; | |
366 | char short_name[8]; | |
367 | const struct fscache_state *(*work)(struct fscache_object *object, | |
368 | int event); | |
369 | const struct fscache_transition transitions[]; | |
370 | }; | |
371 | ||
372 | /* | |
373 | * on-disk cache file or index handle | |
374 | */ | |
375 | struct fscache_object { | |
376 | const struct fscache_state *state; /* Object state machine state */ | |
377 | const struct fscache_transition *oob_table; /* OOB state transition table */ | |
378 | int debug_id; /* debugging ID */ | |
379 | int n_children; /* number of child objects */ | |
380 | int n_ops; /* number of extant ops on object */ | |
381 | int n_obj_ops; /* number of object ops outstanding on object */ | |
382 | int n_in_progress; /* number of ops in progress */ | |
383 | int n_exclusive; /* number of exclusive ops queued or in progress */ | |
384 | atomic_t n_reads; /* number of read ops in progress */ | |
385 | spinlock_t lock; /* state and operations lock */ | |
386 | ||
387 | unsigned long lookup_jif; /* time at which lookup started */ | |
388 | unsigned long oob_event_mask; /* OOB events this object is interested in */ | |
389 | unsigned long event_mask; /* events this object is interested in */ | |
390 | unsigned long events; /* events to be processed by this object | |
391 | * (order is important - using fls) */ | |
392 | ||
393 | unsigned long flags; | |
394 | #define FSCACHE_OBJECT_LOCK 0 /* T if object is busy being processed */ | |
395 | #define FSCACHE_OBJECT_PENDING_WRITE 1 /* T if object has pending write */ | |
396 | #define FSCACHE_OBJECT_WAITING 2 /* T if object is waiting on its parent */ | |
397 | #define FSCACHE_OBJECT_IS_LIVE 3 /* T if object is not withdrawn or relinquished */ | |
398 | #define FSCACHE_OBJECT_IS_LOOKED_UP 4 /* T if object has been looked up */ | |
399 | #define FSCACHE_OBJECT_IS_AVAILABLE 5 /* T if object has become active */ | |
400 | ||
401 | struct list_head cache_link; /* link in cache->object_list */ | |
402 | struct hlist_node cookie_link; /* link in cookie->backing_objects */ | |
403 | struct fscache_cache *cache; /* cache that supplied this object */ | |
404 | struct fscache_cookie *cookie; /* netfs's file/index object */ | |
405 | struct fscache_object *parent; /* parent object */ | |
406 | struct work_struct work; /* attention scheduling record */ | |
407 | struct list_head dependents; /* FIFO of dependent objects */ | |
408 | struct list_head dep_link; /* link in parent's dependents list */ | |
409 | struct list_head pending_ops; /* unstarted operations on this object */ | |
410 | #ifdef CONFIG_FSCACHE_OBJECT_LIST | |
411 | struct rb_node objlist_link; /* link in global object list */ | |
412 | #endif | |
413 | pgoff_t store_limit; /* current storage limit */ | |
414 | loff_t store_limit_l; /* current storage limit */ | |
415 | }; | |
416 | ||
417 | extern void fscache_object_init(struct fscache_object *, struct fscache_cookie *, | |
418 | struct fscache_cache *); | |
419 | extern void fscache_object_destroy(struct fscache_object *); | |
420 | ||
421 | extern void fscache_object_lookup_negative(struct fscache_object *object); | |
422 | extern void fscache_obtained_object(struct fscache_object *object); | |
423 | ||
424 | static inline bool fscache_object_is_live(struct fscache_object *object) | |
425 | { | |
426 | return test_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags); | |
427 | } | |
428 | ||
429 | static inline bool fscache_object_is_dying(struct fscache_object *object) | |
430 | { | |
431 | return !fscache_object_is_live(object); | |
432 | } | |
433 | ||
434 | static inline bool fscache_object_is_available(struct fscache_object *object) | |
435 | { | |
436 | return test_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags); | |
437 | } | |
438 | ||
439 | static inline bool fscache_object_is_active(struct fscache_object *object) | |
440 | { | |
441 | return fscache_object_is_available(object) && | |
442 | fscache_object_is_live(object) && | |
443 | !test_bit(FSCACHE_IOERROR, &object->cache->flags); | |
444 | } | |
445 | ||
446 | static inline bool fscache_object_is_dead(struct fscache_object *object) | |
447 | { | |
448 | return fscache_object_is_dying(object) && | |
449 | test_bit(FSCACHE_IOERROR, &object->cache->flags); | |
450 | } | |
451 | ||
452 | /** | |
453 | * fscache_object_destroyed - Note destruction of an object in a cache | |
454 | * @cache: The cache from which the object came | |
455 | * | |
456 | * Note the destruction and deallocation of an object record in a cache. | |
457 | */ | |
458 | static inline void fscache_object_destroyed(struct fscache_cache *cache) | |
459 | { | |
460 | if (atomic_dec_and_test(&cache->object_count)) | |
461 | wake_up_all(&fscache_cache_cleared_wq); | |
462 | } | |
463 | ||
464 | /** | |
465 | * fscache_object_lookup_error - Note an object encountered an error | |
466 | * @object: The object on which the error was encountered | |
467 | * | |
468 | * Note that an object encountered a fatal error (usually an I/O error) and | |
469 | * that it should be withdrawn as soon as possible. | |
470 | */ | |
471 | static inline void fscache_object_lookup_error(struct fscache_object *object) | |
472 | { | |
473 | set_bit(FSCACHE_OBJECT_EV_ERROR, &object->events); | |
474 | } | |
475 | ||
476 | /** | |
477 | * fscache_set_store_limit - Set the maximum size to be stored in an object | |
478 | * @object: The object to set the maximum on | |
479 | * @i_size: The limit to set in bytes | |
480 | * | |
481 | * Set the maximum size an object is permitted to reach, implying the highest | |
482 | * byte that may be written. Intended to be called by the attr_changed() op. | |
483 | * | |
484 | * See Documentation/filesystems/caching/backend-api.txt for a complete | |
485 | * description. | |
486 | */ | |
487 | static inline | |
488 | void fscache_set_store_limit(struct fscache_object *object, loff_t i_size) | |
489 | { | |
490 | object->store_limit_l = i_size; | |
491 | object->store_limit = i_size >> PAGE_SHIFT; | |
492 | if (i_size & ~PAGE_MASK) | |
493 | object->store_limit++; | |
494 | } | |
495 | ||
496 | /** | |
497 | * fscache_end_io - End a retrieval operation on a page | |
498 | * @op: The FS-Cache operation covering the retrieval | |
499 | * @page: The page that was to be fetched | |
500 | * @error: The error code (0 if successful) | |
501 | * | |
502 | * Note the end of an operation to retrieve a page, as covered by a particular | |
503 | * operation record. | |
504 | */ | |
505 | static inline void fscache_end_io(struct fscache_retrieval *op, | |
506 | struct page *page, int error) | |
507 | { | |
508 | op->end_io_func(page, op->context, error); | |
509 | } | |
510 | ||
511 | /** | |
512 | * fscache_use_cookie - Request usage of cookie attached to an object | |
513 | * @object: Object description | |
514 | * | |
515 | * Request usage of the cookie attached to an object. NULL is returned if the | |
516 | * relinquishment had reduced the cookie usage count to 0. | |
517 | */ | |
518 | static inline bool fscache_use_cookie(struct fscache_object *object) | |
519 | { | |
520 | struct fscache_cookie *cookie = object->cookie; | |
521 | return atomic_inc_not_zero(&cookie->n_active) != 0; | |
522 | } | |
523 | ||
524 | /** | |
525 | * fscache_unuse_cookie - Cease usage of cookie attached to an object | |
526 | * @object: Object description | |
527 | * | |
528 | * Cease usage of the cookie attached to an object. When the users count | |
529 | * reaches zero then the cookie relinquishment will be permitted to proceed. | |
530 | */ | |
531 | static inline void fscache_unuse_cookie(struct fscache_object *object) | |
532 | { | |
533 | struct fscache_cookie *cookie = object->cookie; | |
534 | if (atomic_dec_and_test(&cookie->n_active)) | |
535 | wake_up_atomic_t(&cookie->n_active); | |
536 | } | |
537 | ||
538 | /* | |
539 | * out-of-line cache backend functions | |
540 | */ | |
541 | extern __printf(3, 4) | |
542 | void fscache_init_cache(struct fscache_cache *cache, | |
543 | const struct fscache_cache_ops *ops, | |
544 | const char *idfmt, ...); | |
545 | ||
546 | extern int fscache_add_cache(struct fscache_cache *cache, | |
547 | struct fscache_object *fsdef, | |
548 | const char *tagname); | |
549 | extern void fscache_withdraw_cache(struct fscache_cache *cache); | |
550 | ||
551 | extern void fscache_io_error(struct fscache_cache *cache); | |
552 | ||
553 | extern void fscache_mark_page_cached(struct fscache_retrieval *op, | |
554 | struct page *page); | |
555 | ||
556 | extern void fscache_mark_pages_cached(struct fscache_retrieval *op, | |
557 | struct pagevec *pagevec); | |
558 | ||
559 | extern bool fscache_object_sleep_till_congested(signed long *timeoutp); | |
560 | ||
561 | extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object, | |
562 | const void *data, | |
563 | uint16_t datalen); | |
564 | ||
565 | #endif /* _LINUX_FSCACHE_CACHE_H */ |