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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/slow-work.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 | ||
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); | |
77 | ||
78 | struct fscache_operation { | |
79 | union { | |
80 | struct work_struct fast_work; /* record for fast ops */ | |
81 | struct slow_work slow_work; /* record for (very) slow ops */ | |
82 | }; | |
83 | struct list_head pend_link; /* link in object->pending_ops */ | |
84 | struct fscache_object *object; /* object to be operated upon */ | |
85 | ||
86 | unsigned long flags; | |
87 | #define FSCACHE_OP_TYPE 0x000f /* operation type */ | |
88 | #define FSCACHE_OP_FAST 0x0001 /* - fast op, processor may not sleep for disk */ | |
89 | #define FSCACHE_OP_SLOW 0x0002 /* - (very) slow op, processor may sleep for disk */ | |
90 | #define FSCACHE_OP_MYTHREAD 0x0003 /* - processing is done be issuing thread, not pool */ | |
91 | #define FSCACHE_OP_WAITING 4 /* cleared when op is woken */ | |
92 | #define FSCACHE_OP_EXCLUSIVE 5 /* exclusive op, other ops must wait */ | |
93 | #define FSCACHE_OP_DEAD 6 /* op is now dead */ | |
94 | ||
95 | atomic_t usage; | |
96 | unsigned debug_id; /* debugging ID */ | |
97 | ||
98 | /* operation processor callback | |
99 | * - can be NULL if FSCACHE_OP_WAITING is going to be used to perform | |
100 | * the op in a non-pool thread */ | |
101 | fscache_operation_processor_t processor; | |
102 | ||
103 | /* operation releaser */ | |
104 | fscache_operation_release_t release; | |
440f0aff DH |
105 | |
106 | #ifdef CONFIG_SLOW_WORK_PROC | |
107 | const char *name; /* operation name */ | |
108 | const char *state; /* operation state */ | |
109 | #define fscache_set_op_name(OP, N) do { (OP)->name = (N); } while(0) | |
110 | #define fscache_set_op_state(OP, S) do { (OP)->state = (S); } while(0) | |
111 | #else | |
112 | #define fscache_set_op_name(OP, N) do { } while(0) | |
113 | #define fscache_set_op_state(OP, S) do { } while(0) | |
114 | #endif | |
0dfc41d1 DH |
115 | }; |
116 | ||
117 | extern atomic_t fscache_op_debug_id; | |
118 | extern const struct slow_work_ops fscache_op_slow_work_ops; | |
119 | ||
120 | extern void fscache_enqueue_operation(struct fscache_operation *); | |
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, either fast_work or slow_work if necessary, and processor if needed. | |
130 | */ | |
131 | static inline void fscache_operation_init(struct fscache_operation *op, | |
132 | fscache_operation_release_t release) | |
133 | { | |
134 | atomic_set(&op->usage, 1); | |
135 | op->debug_id = atomic_inc_return(&fscache_op_debug_id); | |
136 | op->release = release; | |
137 | INIT_LIST_HEAD(&op->pend_link); | |
440f0aff | 138 | fscache_set_op_state(op, "Init"); |
0dfc41d1 DH |
139 | } |
140 | ||
141 | /** | |
142 | * fscache_operation_init_slow - Do additional initialisation of a slow op | |
143 | * @op: The operation to initialise | |
144 | * @processor: The processor function to assign | |
145 | * | |
146 | * Do additional initialisation of an operation as required for slow work. | |
147 | */ | |
148 | static inline | |
149 | void fscache_operation_init_slow(struct fscache_operation *op, | |
150 | fscache_operation_processor_t processor) | |
151 | { | |
152 | op->processor = processor; | |
153 | slow_work_init(&op->slow_work, &fscache_op_slow_work_ops); | |
154 | } | |
155 | ||
156 | /* | |
157 | * data read operation | |
158 | */ | |
159 | struct fscache_retrieval { | |
160 | struct fscache_operation op; | |
161 | struct address_space *mapping; /* netfs pages */ | |
162 | fscache_rw_complete_t end_io_func; /* function to call on I/O completion */ | |
163 | void *context; /* netfs read context (pinned) */ | |
164 | struct list_head to_do; /* list of things to be done by the backend */ | |
165 | unsigned long start_time; /* time at which retrieval started */ | |
166 | }; | |
167 | ||
168 | typedef int (*fscache_page_retrieval_func_t)(struct fscache_retrieval *op, | |
169 | struct page *page, | |
170 | gfp_t gfp); | |
171 | ||
172 | typedef int (*fscache_pages_retrieval_func_t)(struct fscache_retrieval *op, | |
173 | struct list_head *pages, | |
174 | unsigned *nr_pages, | |
175 | gfp_t gfp); | |
176 | ||
177 | /** | |
178 | * fscache_get_retrieval - Get an extra reference on a retrieval operation | |
179 | * @op: The retrieval operation to get a reference on | |
180 | * | |
181 | * Get an extra reference on a retrieval operation. | |
182 | */ | |
183 | static inline | |
184 | struct fscache_retrieval *fscache_get_retrieval(struct fscache_retrieval *op) | |
185 | { | |
186 | atomic_inc(&op->op.usage); | |
187 | return op; | |
188 | } | |
189 | ||
190 | /** | |
191 | * fscache_enqueue_retrieval - Enqueue a retrieval operation for processing | |
192 | * @op: The retrieval operation affected | |
193 | * | |
194 | * Enqueue a retrieval operation for processing by the FS-Cache thread pool. | |
195 | */ | |
196 | static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op) | |
197 | { | |
198 | fscache_enqueue_operation(&op->op); | |
199 | } | |
200 | ||
201 | /** | |
202 | * fscache_put_retrieval - Drop a reference to a retrieval operation | |
203 | * @op: The retrieval operation affected | |
204 | * | |
205 | * Drop a reference to a retrieval operation. | |
206 | */ | |
207 | static inline void fscache_put_retrieval(struct fscache_retrieval *op) | |
208 | { | |
209 | fscache_put_operation(&op->op); | |
210 | } | |
211 | ||
212 | /* | |
213 | * cached page storage work item | |
214 | * - used to do three things: | |
215 | * - batch writes to the cache | |
216 | * - do cache writes asynchronously | |
217 | * - defer writes until cache object lookup completion | |
218 | */ | |
219 | struct fscache_storage { | |
220 | struct fscache_operation op; | |
221 | pgoff_t store_limit; /* don't write more than this */ | |
222 | }; | |
223 | ||
224 | /* | |
225 | * cache operations | |
226 | */ | |
227 | struct fscache_cache_ops { | |
228 | /* name of cache provider */ | |
229 | const char *name; | |
230 | ||
231 | /* allocate an object record for a cookie */ | |
232 | struct fscache_object *(*alloc_object)(struct fscache_cache *cache, | |
233 | struct fscache_cookie *cookie); | |
234 | ||
235 | /* look up the object for a cookie */ | |
236 | void (*lookup_object)(struct fscache_object *object); | |
237 | ||
238 | /* finished looking up */ | |
239 | void (*lookup_complete)(struct fscache_object *object); | |
240 | ||
241 | /* increment the usage count on this object (may fail if unmounting) */ | |
242 | struct fscache_object *(*grab_object)(struct fscache_object *object); | |
243 | ||
244 | /* pin an object in the cache */ | |
245 | int (*pin_object)(struct fscache_object *object); | |
246 | ||
247 | /* unpin an object in the cache */ | |
248 | void (*unpin_object)(struct fscache_object *object); | |
249 | ||
250 | /* store the updated auxilliary data on an object */ | |
251 | void (*update_object)(struct fscache_object *object); | |
252 | ||
253 | /* discard the resources pinned by an object and effect retirement if | |
254 | * necessary */ | |
255 | void (*drop_object)(struct fscache_object *object); | |
256 | ||
257 | /* dispose of a reference to an object */ | |
258 | void (*put_object)(struct fscache_object *object); | |
259 | ||
260 | /* sync a cache */ | |
261 | void (*sync_cache)(struct fscache_cache *cache); | |
262 | ||
263 | /* notification that the attributes of a non-index object (such as | |
264 | * i_size) have changed */ | |
265 | int (*attr_changed)(struct fscache_object *object); | |
266 | ||
267 | /* reserve space for an object's data and associated metadata */ | |
268 | int (*reserve_space)(struct fscache_object *object, loff_t i_size); | |
269 | ||
270 | /* request a backing block for a page be read or allocated in the | |
271 | * cache */ | |
272 | fscache_page_retrieval_func_t read_or_alloc_page; | |
273 | ||
274 | /* request backing blocks for a list of pages be read or allocated in | |
275 | * the cache */ | |
276 | fscache_pages_retrieval_func_t read_or_alloc_pages; | |
277 | ||
278 | /* request a backing block for a page be allocated in the cache so that | |
279 | * it can be written directly */ | |
280 | fscache_page_retrieval_func_t allocate_page; | |
281 | ||
282 | /* request backing blocks for pages be allocated in the cache so that | |
283 | * they can be written directly */ | |
284 | fscache_pages_retrieval_func_t allocate_pages; | |
285 | ||
286 | /* write a page to its backing block in the cache */ | |
287 | int (*write_page)(struct fscache_storage *op, struct page *page); | |
288 | ||
289 | /* detach backing block from a page (optional) | |
290 | * - must release the cookie lock before returning | |
291 | * - may sleep | |
292 | */ | |
293 | void (*uncache_page)(struct fscache_object *object, | |
294 | struct page *page); | |
295 | ||
296 | /* dissociate a cache from all the pages it was backing */ | |
297 | void (*dissociate_pages)(struct fscache_cache *cache); | |
298 | }; | |
299 | ||
300 | /* | |
301 | * data file or index object cookie | |
302 | * - a file will only appear in one cache | |
303 | * - a request to cache a file may or may not be honoured, subject to | |
304 | * constraints such as disk space | |
305 | * - indices are created on disk just-in-time | |
306 | */ | |
307 | struct fscache_cookie { | |
308 | atomic_t usage; /* number of users of this cookie */ | |
309 | atomic_t n_children; /* number of children of this cookie */ | |
310 | spinlock_t lock; | |
311 | struct hlist_head backing_objects; /* object(s) backing this file/index */ | |
312 | const struct fscache_cookie_def *def; /* definition */ | |
313 | struct fscache_cookie *parent; /* parent of this entry */ | |
314 | void *netfs_data; /* back pointer to netfs */ | |
315 | struct radix_tree_root stores; /* pages to be stored on this cookie */ | |
316 | #define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */ | |
317 | ||
318 | unsigned long flags; | |
319 | #define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */ | |
320 | #define FSCACHE_COOKIE_CREATING 1 /* T if non-index object being created still */ | |
321 | #define FSCACHE_COOKIE_NO_DATA_YET 2 /* T if new object with no cached data yet */ | |
322 | #define FSCACHE_COOKIE_PENDING_FILL 3 /* T if pending initial fill on object */ | |
323 | #define FSCACHE_COOKIE_FILLING 4 /* T if filling object incrementally */ | |
324 | #define FSCACHE_COOKIE_UNAVAILABLE 5 /* T if cookie is unavailable (error, etc) */ | |
325 | }; | |
326 | ||
327 | extern struct fscache_cookie fscache_fsdef_index; | |
328 | ||
329 | /* | |
330 | * on-disk cache file or index handle | |
331 | */ | |
332 | struct fscache_object { | |
333 | enum fscache_object_state { | |
334 | FSCACHE_OBJECT_INIT, /* object in initial unbound state */ | |
335 | FSCACHE_OBJECT_LOOKING_UP, /* looking up object */ | |
336 | FSCACHE_OBJECT_CREATING, /* creating object */ | |
337 | ||
338 | /* active states */ | |
339 | FSCACHE_OBJECT_AVAILABLE, /* cleaning up object after creation */ | |
340 | FSCACHE_OBJECT_ACTIVE, /* object is usable */ | |
341 | FSCACHE_OBJECT_UPDATING, /* object is updating */ | |
342 | ||
343 | /* terminal states */ | |
344 | FSCACHE_OBJECT_DYING, /* object waiting for accessors to finish */ | |
345 | FSCACHE_OBJECT_LC_DYING, /* object cleaning up after lookup/create */ | |
346 | FSCACHE_OBJECT_ABORT_INIT, /* abort the init state */ | |
347 | FSCACHE_OBJECT_RELEASING, /* releasing object */ | |
348 | FSCACHE_OBJECT_RECYCLING, /* retiring object */ | |
349 | FSCACHE_OBJECT_WITHDRAWING, /* withdrawing object */ | |
350 | FSCACHE_OBJECT_DEAD, /* object is now dead */ | |
440f0aff | 351 | FSCACHE_OBJECT__NSTATES |
0dfc41d1 DH |
352 | } state; |
353 | ||
354 | int debug_id; /* debugging ID */ | |
355 | int n_children; /* number of child objects */ | |
356 | int n_ops; /* number of ops outstanding on object */ | |
357 | int n_obj_ops; /* number of object ops outstanding on object */ | |
358 | int n_in_progress; /* number of ops in progress */ | |
359 | int n_exclusive; /* number of exclusive ops queued */ | |
360 | spinlock_t lock; /* state and operations lock */ | |
361 | ||
362 | unsigned long lookup_jif; /* time at which lookup started */ | |
363 | unsigned long event_mask; /* events this object is interested in */ | |
364 | unsigned long events; /* events to be processed by this object | |
365 | * (order is important - using fls) */ | |
366 | #define FSCACHE_OBJECT_EV_REQUEUE 0 /* T if object should be requeued */ | |
367 | #define FSCACHE_OBJECT_EV_UPDATE 1 /* T if object should be updated */ | |
368 | #define FSCACHE_OBJECT_EV_CLEARED 2 /* T if accessors all gone */ | |
369 | #define FSCACHE_OBJECT_EV_ERROR 3 /* T if fatal error occurred during processing */ | |
370 | #define FSCACHE_OBJECT_EV_RELEASE 4 /* T if netfs requested object release */ | |
371 | #define FSCACHE_OBJECT_EV_RETIRE 5 /* T if netfs requested object retirement */ | |
372 | #define FSCACHE_OBJECT_EV_WITHDRAW 6 /* T if cache requested object withdrawal */ | |
373 | ||
374 | unsigned long flags; | |
375 | #define FSCACHE_OBJECT_LOCK 0 /* T if object is busy being processed */ | |
376 | #define FSCACHE_OBJECT_PENDING_WRITE 1 /* T if object has pending write */ | |
377 | #define FSCACHE_OBJECT_WAITING 2 /* T if object is waiting on its parent */ | |
378 | ||
379 | struct list_head cache_link; /* link in cache->object_list */ | |
380 | struct hlist_node cookie_link; /* link in cookie->backing_objects */ | |
381 | struct fscache_cache *cache; /* cache that supplied this object */ | |
382 | struct fscache_cookie *cookie; /* netfs's file/index object */ | |
383 | struct fscache_object *parent; /* parent object */ | |
384 | struct slow_work work; /* attention scheduling record */ | |
385 | struct list_head dependents; /* FIFO of dependent objects */ | |
386 | struct list_head dep_link; /* link in parent's dependents list */ | |
387 | struct list_head pending_ops; /* unstarted operations on this object */ | |
388 | pgoff_t store_limit; /* current storage limit */ | |
389 | }; | |
390 | ||
391 | extern const char *fscache_object_states[]; | |
392 | ||
393 | #define fscache_object_is_active(obj) \ | |
394 | (!test_bit(FSCACHE_IOERROR, &(obj)->cache->flags) && \ | |
395 | (obj)->state >= FSCACHE_OBJECT_AVAILABLE && \ | |
396 | (obj)->state < FSCACHE_OBJECT_DYING) | |
397 | ||
398 | extern const struct slow_work_ops fscache_object_slow_work_ops; | |
399 | ||
400 | /** | |
401 | * fscache_object_init - Initialise a cache object description | |
402 | * @object: Object description | |
403 | * | |
404 | * Initialise a cache object description to its basic values. | |
405 | * | |
406 | * See Documentation/filesystems/caching/backend-api.txt for a complete | |
407 | * description. | |
408 | */ | |
409 | static inline | |
410 | void fscache_object_init(struct fscache_object *object, | |
411 | struct fscache_cookie *cookie, | |
412 | struct fscache_cache *cache) | |
413 | { | |
414 | atomic_inc(&cache->object_count); | |
415 | ||
416 | object->state = FSCACHE_OBJECT_INIT; | |
417 | spin_lock_init(&object->lock); | |
418 | INIT_LIST_HEAD(&object->cache_link); | |
419 | INIT_HLIST_NODE(&object->cookie_link); | |
420 | vslow_work_init(&object->work, &fscache_object_slow_work_ops); | |
421 | INIT_LIST_HEAD(&object->dependents); | |
422 | INIT_LIST_HEAD(&object->dep_link); | |
423 | INIT_LIST_HEAD(&object->pending_ops); | |
424 | object->n_children = 0; | |
425 | object->n_ops = object->n_in_progress = object->n_exclusive = 0; | |
426 | object->events = object->event_mask = 0; | |
427 | object->flags = 0; | |
428 | object->store_limit = 0; | |
429 | object->cache = cache; | |
430 | object->cookie = cookie; | |
431 | object->parent = NULL; | |
432 | } | |
433 | ||
434 | extern void fscache_object_lookup_negative(struct fscache_object *object); | |
435 | extern void fscache_obtained_object(struct fscache_object *object); | |
436 | ||
437 | /** | |
438 | * fscache_object_destroyed - Note destruction of an object in a cache | |
439 | * @cache: The cache from which the object came | |
440 | * | |
441 | * Note the destruction and deallocation of an object record in a cache. | |
442 | */ | |
443 | static inline void fscache_object_destroyed(struct fscache_cache *cache) | |
444 | { | |
445 | if (atomic_dec_and_test(&cache->object_count)) | |
446 | wake_up_all(&fscache_cache_cleared_wq); | |
447 | } | |
448 | ||
449 | /** | |
450 | * fscache_object_lookup_error - Note an object encountered an error | |
451 | * @object: The object on which the error was encountered | |
452 | * | |
453 | * Note that an object encountered a fatal error (usually an I/O error) and | |
454 | * that it should be withdrawn as soon as possible. | |
455 | */ | |
456 | static inline void fscache_object_lookup_error(struct fscache_object *object) | |
457 | { | |
458 | set_bit(FSCACHE_OBJECT_EV_ERROR, &object->events); | |
459 | } | |
460 | ||
461 | /** | |
462 | * fscache_set_store_limit - Set the maximum size to be stored in an object | |
463 | * @object: The object to set the maximum on | |
464 | * @i_size: The limit to set in bytes | |
465 | * | |
466 | * Set the maximum size an object is permitted to reach, implying the highest | |
467 | * byte that may be written. Intended to be called by the attr_changed() op. | |
468 | * | |
469 | * See Documentation/filesystems/caching/backend-api.txt for a complete | |
470 | * description. | |
471 | */ | |
472 | static inline | |
473 | void fscache_set_store_limit(struct fscache_object *object, loff_t i_size) | |
474 | { | |
475 | object->store_limit = i_size >> PAGE_SHIFT; | |
476 | if (i_size & ~PAGE_MASK) | |
477 | object->store_limit++; | |
478 | } | |
479 | ||
480 | /** | |
481 | * fscache_end_io - End a retrieval operation on a page | |
482 | * @op: The FS-Cache operation covering the retrieval | |
483 | * @page: The page that was to be fetched | |
484 | * @error: The error code (0 if successful) | |
485 | * | |
486 | * Note the end of an operation to retrieve a page, as covered by a particular | |
487 | * operation record. | |
488 | */ | |
489 | static inline void fscache_end_io(struct fscache_retrieval *op, | |
490 | struct page *page, int error) | |
491 | { | |
492 | op->end_io_func(page, op->context, error); | |
493 | } | |
494 | ||
495 | /* | |
496 | * out-of-line cache backend functions | |
497 | */ | |
498 | extern void fscache_init_cache(struct fscache_cache *cache, | |
499 | const struct fscache_cache_ops *ops, | |
500 | const char *idfmt, | |
501 | ...) __attribute__ ((format (printf, 3, 4))); | |
502 | ||
503 | extern int fscache_add_cache(struct fscache_cache *cache, | |
504 | struct fscache_object *fsdef, | |
505 | const char *tagname); | |
506 | extern void fscache_withdraw_cache(struct fscache_cache *cache); | |
507 | ||
508 | extern void fscache_io_error(struct fscache_cache *cache); | |
509 | ||
510 | extern void fscache_mark_pages_cached(struct fscache_retrieval *op, | |
511 | struct pagevec *pagevec); | |
512 | ||
513 | extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object, | |
514 | const void *data, | |
515 | uint16_t datalen); | |
516 | ||
517 | #endif /* _LINUX_FSCACHE_CACHE_H */ |