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0dfc41d1 DH |
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> | |
8b8edefa | 23 | #include <linux/workqueue.h> |
0dfc41d1 DH |
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 | ||
0dfc41d1 DH |
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); | |
d3b97ca4 | 77 | typedef void (*fscache_operation_cancel_t)(struct fscache_operation *op); |
0dfc41d1 | 78 | |
9f10523f DH |
79 | enum fscache_operation_state { |
80 | FSCACHE_OP_ST_BLANK, /* Op is not yet submitted */ | |
81 | FSCACHE_OP_ST_INITIALISED, /* Op is initialised */ | |
82 | FSCACHE_OP_ST_PENDING, /* Op is blocked from running */ | |
83 | FSCACHE_OP_ST_IN_PROGRESS, /* Op is in progress */ | |
84 | FSCACHE_OP_ST_COMPLETE, /* Op is complete */ | |
85 | FSCACHE_OP_ST_CANCELLED, /* Op has been cancelled */ | |
86 | FSCACHE_OP_ST_DEAD /* Op is now dead */ | |
87 | }; | |
88 | ||
0dfc41d1 | 89 | struct fscache_operation { |
8af7c124 | 90 | struct work_struct work; /* record for async ops */ |
0dfc41d1 DH |
91 | struct list_head pend_link; /* link in object->pending_ops */ |
92 | struct fscache_object *object; /* object to be operated upon */ | |
93 | ||
94 | unsigned long flags; | |
95 | #define FSCACHE_OP_TYPE 0x000f /* operation type */ | |
8af7c124 TH |
96 | #define FSCACHE_OP_ASYNC 0x0001 /* - async op, processor may sleep for disk */ |
97 | #define FSCACHE_OP_MYTHREAD 0x0002 /* - processing is done be issuing thread, not pool */ | |
0dfc41d1 DH |
98 | #define FSCACHE_OP_WAITING 4 /* cleared when op is woken */ |
99 | #define FSCACHE_OP_EXCLUSIVE 5 /* exclusive op, other ops must wait */ | |
9f10523f | 100 | #define FSCACHE_OP_DEC_READ_CNT 6 /* decrement object->n_reads on destruction */ |
1362729b DH |
101 | #define FSCACHE_OP_UNUSE_COOKIE 7 /* call fscache_unuse_cookie() on completion */ |
102 | #define FSCACHE_OP_KEEP_FLAGS 0x00f0 /* flags to keep when repurposing an op */ | |
0dfc41d1 | 103 | |
9f10523f | 104 | enum fscache_operation_state state; |
0dfc41d1 DH |
105 | atomic_t usage; |
106 | unsigned debug_id; /* debugging ID */ | |
107 | ||
108 | /* operation processor callback | |
109 | * - can be NULL if FSCACHE_OP_WAITING is going to be used to perform | |
110 | * the op in a non-pool thread */ | |
111 | fscache_operation_processor_t processor; | |
112 | ||
d3b97ca4 DH |
113 | /* Operation cancellation cleanup (optional) */ |
114 | fscache_operation_cancel_t cancel; | |
115 | ||
0dfc41d1 DH |
116 | /* operation releaser */ |
117 | fscache_operation_release_t release; | |
118 | }; | |
119 | ||
120 | extern atomic_t fscache_op_debug_id; | |
8af7c124 | 121 | extern void fscache_op_work_func(struct work_struct *work); |
0dfc41d1 DH |
122 | |
123 | extern void fscache_enqueue_operation(struct fscache_operation *); | |
1f372dff | 124 | extern void fscache_op_complete(struct fscache_operation *, bool); |
0dfc41d1 | 125 | extern void fscache_put_operation(struct fscache_operation *); |
1339ec98 DH |
126 | extern void fscache_operation_init(struct fscache_operation *, |
127 | fscache_operation_processor_t, | |
d3b97ca4 | 128 | fscache_operation_cancel_t, |
1339ec98 | 129 | fscache_operation_release_t); |
0dfc41d1 | 130 | |
0dfc41d1 DH |
131 | /* |
132 | * data read operation | |
133 | */ | |
134 | struct fscache_retrieval { | |
135 | struct fscache_operation op; | |
136 | struct address_space *mapping; /* netfs pages */ | |
137 | fscache_rw_complete_t end_io_func; /* function to call on I/O completion */ | |
138 | void *context; /* netfs read context (pinned) */ | |
139 | struct list_head to_do; /* list of things to be done by the backend */ | |
140 | unsigned long start_time; /* time at which retrieval started */ | |
1bb4b7f9 | 141 | atomic_t n_pages; /* number of pages to be retrieved */ |
0dfc41d1 DH |
142 | }; |
143 | ||
144 | typedef int (*fscache_page_retrieval_func_t)(struct fscache_retrieval *op, | |
145 | struct page *page, | |
146 | gfp_t gfp); | |
147 | ||
148 | typedef int (*fscache_pages_retrieval_func_t)(struct fscache_retrieval *op, | |
149 | struct list_head *pages, | |
150 | unsigned *nr_pages, | |
151 | gfp_t gfp); | |
152 | ||
153 | /** | |
154 | * fscache_get_retrieval - Get an extra reference on a retrieval operation | |
155 | * @op: The retrieval operation to get a reference on | |
156 | * | |
157 | * Get an extra reference on a retrieval operation. | |
158 | */ | |
159 | static inline | |
160 | struct fscache_retrieval *fscache_get_retrieval(struct fscache_retrieval *op) | |
161 | { | |
162 | atomic_inc(&op->op.usage); | |
163 | return op; | |
164 | } | |
165 | ||
166 | /** | |
167 | * fscache_enqueue_retrieval - Enqueue a retrieval operation for processing | |
168 | * @op: The retrieval operation affected | |
169 | * | |
170 | * Enqueue a retrieval operation for processing by the FS-Cache thread pool. | |
171 | */ | |
172 | static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op) | |
173 | { | |
174 | fscache_enqueue_operation(&op->op); | |
175 | } | |
176 | ||
9f10523f DH |
177 | /** |
178 | * fscache_retrieval_complete - Record (partial) completion of a retrieval | |
179 | * @op: The retrieval operation affected | |
180 | * @n_pages: The number of pages to account for | |
181 | */ | |
182 | static inline void fscache_retrieval_complete(struct fscache_retrieval *op, | |
183 | int n_pages) | |
184 | { | |
1bb4b7f9 DH |
185 | atomic_sub(n_pages, &op->n_pages); |
186 | if (atomic_read(&op->n_pages) <= 0) | |
1f372dff | 187 | fscache_op_complete(&op->op, true); |
9f10523f DH |
188 | } |
189 | ||
0dfc41d1 DH |
190 | /** |
191 | * fscache_put_retrieval - Drop a reference to a retrieval operation | |
192 | * @op: The retrieval operation affected | |
193 | * | |
194 | * Drop a reference to a retrieval operation. | |
195 | */ | |
196 | static inline void fscache_put_retrieval(struct fscache_retrieval *op) | |
197 | { | |
198 | fscache_put_operation(&op->op); | |
199 | } | |
200 | ||
201 | /* | |
202 | * cached page storage work item | |
203 | * - used to do three things: | |
204 | * - batch writes to the cache | |
205 | * - do cache writes asynchronously | |
206 | * - defer writes until cache object lookup completion | |
207 | */ | |
208 | struct fscache_storage { | |
209 | struct fscache_operation op; | |
210 | pgoff_t store_limit; /* don't write more than this */ | |
211 | }; | |
212 | ||
213 | /* | |
214 | * cache operations | |
215 | */ | |
216 | struct fscache_cache_ops { | |
217 | /* name of cache provider */ | |
218 | const char *name; | |
219 | ||
220 | /* allocate an object record for a cookie */ | |
221 | struct fscache_object *(*alloc_object)(struct fscache_cache *cache, | |
222 | struct fscache_cookie *cookie); | |
223 | ||
fee096de DH |
224 | /* look up the object for a cookie |
225 | * - return -ETIMEDOUT to be requeued | |
226 | */ | |
227 | int (*lookup_object)(struct fscache_object *object); | |
0dfc41d1 DH |
228 | |
229 | /* finished looking up */ | |
230 | void (*lookup_complete)(struct fscache_object *object); | |
231 | ||
232 | /* increment the usage count on this object (may fail if unmounting) */ | |
233 | struct fscache_object *(*grab_object)(struct fscache_object *object); | |
234 | ||
235 | /* pin an object in the cache */ | |
236 | int (*pin_object)(struct fscache_object *object); | |
237 | ||
238 | /* unpin an object in the cache */ | |
239 | void (*unpin_object)(struct fscache_object *object); | |
240 | ||
da9803bc DH |
241 | /* check the consistency between the backing cache and the FS-Cache |
242 | * cookie */ | |
243 | bool (*check_consistency)(struct fscache_operation *op); | |
244 | ||
25985edc | 245 | /* store the updated auxiliary data on an object */ |
0dfc41d1 DH |
246 | void (*update_object)(struct fscache_object *object); |
247 | ||
ef778e7a DH |
248 | /* Invalidate an object */ |
249 | void (*invalidate_object)(struct fscache_operation *op); | |
250 | ||
0dfc41d1 DH |
251 | /* discard the resources pinned by an object and effect retirement if |
252 | * necessary */ | |
253 | void (*drop_object)(struct fscache_object *object); | |
254 | ||
255 | /* dispose of a reference to an object */ | |
256 | void (*put_object)(struct fscache_object *object); | |
257 | ||
258 | /* sync a cache */ | |
259 | void (*sync_cache)(struct fscache_cache *cache); | |
260 | ||
261 | /* notification that the attributes of a non-index object (such as | |
262 | * i_size) have changed */ | |
263 | int (*attr_changed)(struct fscache_object *object); | |
264 | ||
265 | /* reserve space for an object's data and associated metadata */ | |
266 | int (*reserve_space)(struct fscache_object *object, loff_t i_size); | |
267 | ||
268 | /* request a backing block for a page be read or allocated in the | |
269 | * cache */ | |
270 | fscache_page_retrieval_func_t read_or_alloc_page; | |
271 | ||
272 | /* request backing blocks for a list of pages be read or allocated in | |
273 | * the cache */ | |
274 | fscache_pages_retrieval_func_t read_or_alloc_pages; | |
275 | ||
276 | /* request a backing block for a page be allocated in the cache so that | |
277 | * it can be written directly */ | |
278 | fscache_page_retrieval_func_t allocate_page; | |
279 | ||
280 | /* request backing blocks for pages be allocated in the cache so that | |
281 | * they can be written directly */ | |
282 | fscache_pages_retrieval_func_t allocate_pages; | |
283 | ||
284 | /* write a page to its backing block in the cache */ | |
285 | int (*write_page)(struct fscache_storage *op, struct page *page); | |
286 | ||
287 | /* detach backing block from a page (optional) | |
288 | * - must release the cookie lock before returning | |
289 | * - may sleep | |
290 | */ | |
291 | void (*uncache_page)(struct fscache_object *object, | |
292 | struct page *page); | |
293 | ||
294 | /* dissociate a cache from all the pages it was backing */ | |
295 | void (*dissociate_pages)(struct fscache_cache *cache); | |
296 | }; | |
297 | ||
0dfc41d1 DH |
298 | extern struct fscache_cookie fscache_fsdef_index; |
299 | ||
36a02de5 DH |
300 | /* |
301 | * Event list for fscache_object::{event_mask,events} | |
302 | */ | |
303 | enum { | |
caaef690 DH |
304 | FSCACHE_OBJECT_EV_NEW_CHILD, /* T if object has a new child */ |
305 | FSCACHE_OBJECT_EV_PARENT_READY, /* T if object's parent is ready */ | |
36a02de5 DH |
306 | FSCACHE_OBJECT_EV_UPDATE, /* T if object should be updated */ |
307 | FSCACHE_OBJECT_EV_INVALIDATE, /* T if cache requested object invalidation */ | |
308 | FSCACHE_OBJECT_EV_CLEARED, /* T if accessors all gone */ | |
309 | FSCACHE_OBJECT_EV_ERROR, /* T if fatal error occurred during processing */ | |
caaef690 | 310 | FSCACHE_OBJECT_EV_KILL, /* T if netfs relinquished or cache withdrew object */ |
36a02de5 DH |
311 | NR_FSCACHE_OBJECT_EVENTS |
312 | }; | |
313 | ||
314 | #define FSCACHE_OBJECT_EVENTS_MASK ((1UL << NR_FSCACHE_OBJECT_EVENTS) - 1) | |
315 | ||
caaef690 DH |
316 | /* |
317 | * States for object state machine. | |
318 | */ | |
319 | struct fscache_transition { | |
320 | unsigned long events; | |
321 | const struct fscache_state *transit_to; | |
322 | }; | |
323 | ||
324 | struct fscache_state { | |
325 | char name[24]; | |
326 | char short_name[8]; | |
327 | const struct fscache_state *(*work)(struct fscache_object *object, | |
328 | int event); | |
329 | const struct fscache_transition transitions[]; | |
330 | }; | |
331 | ||
0dfc41d1 DH |
332 | /* |
333 | * on-disk cache file or index handle | |
334 | */ | |
335 | struct fscache_object { | |
caaef690 DH |
336 | const struct fscache_state *state; /* Object state machine state */ |
337 | const struct fscache_transition *oob_table; /* OOB state transition table */ | |
0dfc41d1 DH |
338 | int debug_id; /* debugging ID */ |
339 | int n_children; /* number of child objects */ | |
9f10523f | 340 | int n_ops; /* number of extant ops on object */ |
0dfc41d1 DH |
341 | int n_obj_ops; /* number of object ops outstanding on object */ |
342 | int n_in_progress; /* number of ops in progress */ | |
9f10523f | 343 | int n_exclusive; /* number of exclusive ops queued or in progress */ |
4fbf4291 | 344 | atomic_t n_reads; /* number of read ops in progress */ |
0dfc41d1 DH |
345 | spinlock_t lock; /* state and operations lock */ |
346 | ||
347 | unsigned long lookup_jif; /* time at which lookup started */ | |
caaef690 | 348 | unsigned long oob_event_mask; /* OOB events this object is interested in */ |
0dfc41d1 DH |
349 | unsigned long event_mask; /* events this object is interested in */ |
350 | unsigned long events; /* events to be processed by this object | |
351 | * (order is important - using fls) */ | |
0dfc41d1 DH |
352 | |
353 | unsigned long flags; | |
354 | #define FSCACHE_OBJECT_LOCK 0 /* T if object is busy being processed */ | |
355 | #define FSCACHE_OBJECT_PENDING_WRITE 1 /* T if object has pending write */ | |
356 | #define FSCACHE_OBJECT_WAITING 2 /* T if object is waiting on its parent */ | |
1362729b DH |
357 | #define FSCACHE_OBJECT_IS_LIVE 3 /* T if object is not withdrawn or relinquished */ |
358 | #define FSCACHE_OBJECT_IS_LOOKED_UP 4 /* T if object has been looked up */ | |
359 | #define FSCACHE_OBJECT_IS_AVAILABLE 5 /* T if object has become active */ | |
94d30ae9 | 360 | #define FSCACHE_OBJECT_RETIRED 6 /* T if object was retired on relinquishment */ |
182d919b | 361 | #define FSCACHE_OBJECT_KILLED_BY_CACHE 7 /* T if object was killed by the cache */ |
0dfc41d1 DH |
362 | |
363 | struct list_head cache_link; /* link in cache->object_list */ | |
364 | struct hlist_node cookie_link; /* link in cookie->backing_objects */ | |
365 | struct fscache_cache *cache; /* cache that supplied this object */ | |
366 | struct fscache_cookie *cookie; /* netfs's file/index object */ | |
367 | struct fscache_object *parent; /* parent object */ | |
8b8edefa | 368 | struct work_struct work; /* attention scheduling record */ |
0dfc41d1 DH |
369 | struct list_head dependents; /* FIFO of dependent objects */ |
370 | struct list_head dep_link; /* link in parent's dependents list */ | |
371 | struct list_head pending_ops; /* unstarted operations on this object */ | |
4fbf4291 DH |
372 | #ifdef CONFIG_FSCACHE_OBJECT_LIST |
373 | struct rb_node objlist_link; /* link in global object list */ | |
374 | #endif | |
0dfc41d1 | 375 | pgoff_t store_limit; /* current storage limit */ |
a17754fb | 376 | loff_t store_limit_l; /* current storage limit */ |
0dfc41d1 DH |
377 | }; |
378 | ||
610be24e DH |
379 | extern void fscache_object_init(struct fscache_object *, struct fscache_cookie *, |
380 | struct fscache_cache *); | |
1362729b | 381 | extern void fscache_object_destroy(struct fscache_object *); |
0dfc41d1 DH |
382 | |
383 | extern void fscache_object_lookup_negative(struct fscache_object *object); | |
384 | extern void fscache_obtained_object(struct fscache_object *object); | |
385 | ||
493f7bc1 DH |
386 | static inline bool fscache_object_is_live(struct fscache_object *object) |
387 | { | |
caaef690 | 388 | return test_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags); |
493f7bc1 DH |
389 | } |
390 | ||
391 | static inline bool fscache_object_is_dying(struct fscache_object *object) | |
392 | { | |
393 | return !fscache_object_is_live(object); | |
394 | } | |
395 | ||
396 | static inline bool fscache_object_is_available(struct fscache_object *object) | |
397 | { | |
caaef690 | 398 | return test_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags); |
493f7bc1 DH |
399 | } |
400 | ||
30ceec62 DH |
401 | static inline bool fscache_cache_is_broken(struct fscache_object *object) |
402 | { | |
403 | return test_bit(FSCACHE_IOERROR, &object->cache->flags); | |
404 | } | |
405 | ||
493f7bc1 DH |
406 | static inline bool fscache_object_is_active(struct fscache_object *object) |
407 | { | |
408 | return fscache_object_is_available(object) && | |
409 | fscache_object_is_live(object) && | |
30ceec62 | 410 | !fscache_cache_is_broken(object); |
493f7bc1 DH |
411 | } |
412 | ||
0dfc41d1 DH |
413 | /** |
414 | * fscache_object_destroyed - Note destruction of an object in a cache | |
415 | * @cache: The cache from which the object came | |
416 | * | |
417 | * Note the destruction and deallocation of an object record in a cache. | |
418 | */ | |
419 | static inline void fscache_object_destroyed(struct fscache_cache *cache) | |
420 | { | |
421 | if (atomic_dec_and_test(&cache->object_count)) | |
422 | wake_up_all(&fscache_cache_cleared_wq); | |
423 | } | |
424 | ||
425 | /** | |
426 | * fscache_object_lookup_error - Note an object encountered an error | |
427 | * @object: The object on which the error was encountered | |
428 | * | |
429 | * Note that an object encountered a fatal error (usually an I/O error) and | |
430 | * that it should be withdrawn as soon as possible. | |
431 | */ | |
432 | static inline void fscache_object_lookup_error(struct fscache_object *object) | |
433 | { | |
434 | set_bit(FSCACHE_OBJECT_EV_ERROR, &object->events); | |
435 | } | |
436 | ||
437 | /** | |
438 | * fscache_set_store_limit - Set the maximum size to be stored in an object | |
439 | * @object: The object to set the maximum on | |
440 | * @i_size: The limit to set in bytes | |
441 | * | |
442 | * Set the maximum size an object is permitted to reach, implying the highest | |
443 | * byte that may be written. Intended to be called by the attr_changed() op. | |
444 | * | |
445 | * See Documentation/filesystems/caching/backend-api.txt for a complete | |
446 | * description. | |
447 | */ | |
448 | static inline | |
449 | void fscache_set_store_limit(struct fscache_object *object, loff_t i_size) | |
450 | { | |
a17754fb | 451 | object->store_limit_l = i_size; |
0dfc41d1 DH |
452 | object->store_limit = i_size >> PAGE_SHIFT; |
453 | if (i_size & ~PAGE_MASK) | |
454 | object->store_limit++; | |
455 | } | |
456 | ||
457 | /** | |
458 | * fscache_end_io - End a retrieval operation on a page | |
459 | * @op: The FS-Cache operation covering the retrieval | |
460 | * @page: The page that was to be fetched | |
461 | * @error: The error code (0 if successful) | |
462 | * | |
463 | * Note the end of an operation to retrieve a page, as covered by a particular | |
464 | * operation record. | |
465 | */ | |
466 | static inline void fscache_end_io(struct fscache_retrieval *op, | |
467 | struct page *page, int error) | |
468 | { | |
469 | op->end_io_func(page, op->context, error); | |
470 | } | |
471 | ||
8fb883f3 DH |
472 | static inline void __fscache_use_cookie(struct fscache_cookie *cookie) |
473 | { | |
474 | atomic_inc(&cookie->n_active); | |
475 | } | |
476 | ||
1362729b DH |
477 | /** |
478 | * fscache_use_cookie - Request usage of cookie attached to an object | |
479 | * @object: Object description | |
480 | * | |
481 | * Request usage of the cookie attached to an object. NULL is returned if the | |
482 | * relinquishment had reduced the cookie usage count to 0. | |
483 | */ | |
484 | static inline bool fscache_use_cookie(struct fscache_object *object) | |
485 | { | |
486 | struct fscache_cookie *cookie = object->cookie; | |
487 | return atomic_inc_not_zero(&cookie->n_active) != 0; | |
488 | } | |
489 | ||
8fb883f3 DH |
490 | static inline bool __fscache_unuse_cookie(struct fscache_cookie *cookie) |
491 | { | |
492 | return atomic_dec_and_test(&cookie->n_active); | |
493 | } | |
494 | ||
495 | static inline void __fscache_wake_unused_cookie(struct fscache_cookie *cookie) | |
496 | { | |
497 | wake_up_atomic_t(&cookie->n_active); | |
498 | } | |
499 | ||
1362729b DH |
500 | /** |
501 | * fscache_unuse_cookie - Cease usage of cookie attached to an object | |
502 | * @object: Object description | |
503 | * | |
504 | * Cease usage of the cookie attached to an object. When the users count | |
505 | * reaches zero then the cookie relinquishment will be permitted to proceed. | |
506 | */ | |
507 | static inline void fscache_unuse_cookie(struct fscache_object *object) | |
508 | { | |
509 | struct fscache_cookie *cookie = object->cookie; | |
8fb883f3 DH |
510 | if (__fscache_unuse_cookie(cookie)) |
511 | __fscache_wake_unused_cookie(cookie); | |
1362729b DH |
512 | } |
513 | ||
0dfc41d1 DH |
514 | /* |
515 | * out-of-line cache backend functions | |
516 | */ | |
b9075fa9 JP |
517 | extern __printf(3, 4) |
518 | void fscache_init_cache(struct fscache_cache *cache, | |
519 | const struct fscache_cache_ops *ops, | |
520 | const char *idfmt, ...); | |
0dfc41d1 DH |
521 | |
522 | extern int fscache_add_cache(struct fscache_cache *cache, | |
523 | struct fscache_object *fsdef, | |
524 | const char *tagname); | |
525 | extern void fscache_withdraw_cache(struct fscache_cache *cache); | |
526 | ||
527 | extern void fscache_io_error(struct fscache_cache *cache); | |
528 | ||
c4d6d8db DH |
529 | extern void fscache_mark_page_cached(struct fscache_retrieval *op, |
530 | struct page *page); | |
531 | ||
0dfc41d1 DH |
532 | extern void fscache_mark_pages_cached(struct fscache_retrieval *op, |
533 | struct pagevec *pagevec); | |
534 | ||
8b8edefa TH |
535 | extern bool fscache_object_sleep_till_congested(signed long *timeoutp); |
536 | ||
0dfc41d1 DH |
537 | extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object, |
538 | const void *data, | |
539 | uint16_t datalen); | |
540 | ||
182d919b DH |
541 | extern void fscache_object_retrying_stale(struct fscache_object *object); |
542 | ||
543 | enum fscache_why_object_killed { | |
544 | FSCACHE_OBJECT_IS_STALE, | |
545 | FSCACHE_OBJECT_NO_SPACE, | |
546 | FSCACHE_OBJECT_WAS_RETIRED, | |
547 | FSCACHE_OBJECT_WAS_CULLED, | |
548 | }; | |
549 | extern void fscache_object_mark_killed(struct fscache_object *object, | |
550 | enum fscache_why_object_killed why); | |
551 | ||
0dfc41d1 | 552 | #endif /* _LINUX_FSCACHE_CACHE_H */ |