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Linux 3.8-rc7
[cris-mirror.git] / fs / fscache / object.c
blob50d41c1802110b472f93eae0cae5f775d332fd13
1 /* FS-Cache object state machine handler
2 *
3 * Copyright (C) 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 * See Documentation/filesystems/caching/object.txt for a description of the
12 * object state machine and the in-kernel representations.
13 */
14
15 #define FSCACHE_DEBUG_LEVEL COOKIE
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include "internal.h"
19
20 const char *fscache_object_states[FSCACHE_OBJECT__NSTATES] = {
21 [FSCACHE_OBJECT_INIT] = "OBJECT_INIT",
22 [FSCACHE_OBJECT_LOOKING_UP] = "OBJECT_LOOKING_UP",
23 [FSCACHE_OBJECT_CREATING] = "OBJECT_CREATING",
24 [FSCACHE_OBJECT_AVAILABLE] = "OBJECT_AVAILABLE",
25 [FSCACHE_OBJECT_ACTIVE] = "OBJECT_ACTIVE",
26 [FSCACHE_OBJECT_INVALIDATING] = "OBJECT_INVALIDATING",
27 [FSCACHE_OBJECT_UPDATING] = "OBJECT_UPDATING",
28 [FSCACHE_OBJECT_DYING] = "OBJECT_DYING",
29 [FSCACHE_OBJECT_LC_DYING] = "OBJECT_LC_DYING",
30 [FSCACHE_OBJECT_ABORT_INIT] = "OBJECT_ABORT_INIT",
31 [FSCACHE_OBJECT_RELEASING] = "OBJECT_RELEASING",
32 [FSCACHE_OBJECT_RECYCLING] = "OBJECT_RECYCLING",
33 [FSCACHE_OBJECT_WITHDRAWING] = "OBJECT_WITHDRAWING",
34 [FSCACHE_OBJECT_DEAD] = "OBJECT_DEAD",
35 };
36 EXPORT_SYMBOL(fscache_object_states);
37
38 const char fscache_object_states_short[FSCACHE_OBJECT__NSTATES][5] = {
39 [FSCACHE_OBJECT_INIT] = "INIT",
40 [FSCACHE_OBJECT_LOOKING_UP] = "LOOK",
41 [FSCACHE_OBJECT_CREATING] = "CRTN",
42 [FSCACHE_OBJECT_AVAILABLE] = "AVBL",
43 [FSCACHE_OBJECT_ACTIVE] = "ACTV",
44 [FSCACHE_OBJECT_INVALIDATING] = "INVL",
45 [FSCACHE_OBJECT_UPDATING] = "UPDT",
46 [FSCACHE_OBJECT_DYING] = "DYNG",
47 [FSCACHE_OBJECT_LC_DYING] = "LCDY",
48 [FSCACHE_OBJECT_ABORT_INIT] = "ABTI",
49 [FSCACHE_OBJECT_RELEASING] = "RELS",
50 [FSCACHE_OBJECT_RECYCLING] = "RCYC",
51 [FSCACHE_OBJECT_WITHDRAWING] = "WTHD",
52 [FSCACHE_OBJECT_DEAD] = "DEAD",
53 };
54
55 static int fscache_get_object(struct fscache_object *);
56 static void fscache_put_object(struct fscache_object *);
57 static void fscache_initialise_object(struct fscache_object *);
58 static void fscache_lookup_object(struct fscache_object *);
59 static void fscache_object_available(struct fscache_object *);
60 static void fscache_invalidate_object(struct fscache_object *);
61 static void fscache_release_object(struct fscache_object *);
62 static void fscache_withdraw_object(struct fscache_object *);
63 static void fscache_enqueue_dependents(struct fscache_object *);
64 static void fscache_dequeue_object(struct fscache_object *);
65
66 /*
67 * we need to notify the parent when an op completes that we had outstanding
68 * upon it
69 */
70 static inline void fscache_done_parent_op(struct fscache_object *object)
71 {
72 struct fscache_object *parent = object->parent;
73
74 _enter("OBJ%x {OBJ%x,%x}",
75 object->debug_id, parent->debug_id, parent->n_ops);
76
77 spin_lock_nested(&parent->lock, 1);
78 parent->n_ops--;
79 parent->n_obj_ops--;
80 if (parent->n_ops == 0)
81 fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
82 spin_unlock(&parent->lock);
83 }
84
85 /*
86 * Notify netfs of invalidation completion.
87 */
88 static inline void fscache_invalidation_complete(struct fscache_cookie *cookie)
89 {
90 if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
91 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);
92 }
93
94 /*
95 * process events that have been sent to an object's state machine
96 * - initiates parent lookup
97 * - does object lookup
98 * - does object creation
99 * - does object recycling and retirement
100 * - does object withdrawal
101 */
102 static void fscache_object_state_machine(struct fscache_object *object)
103 {
104 enum fscache_object_state new_state;
105 struct fscache_cookie *cookie;
106 int event;
107
108 ASSERT(object != NULL);
109
110 _enter("{OBJ%x,%s,%lx}",
111 object->debug_id, fscache_object_states[object->state],
112 object->events);
113
114 switch (object->state) {
115 /* wait for the parent object to become ready */
116 case FSCACHE_OBJECT_INIT:
117 object->event_mask =
118 FSCACHE_OBJECT_EVENTS_MASK &
119 ~(1 << FSCACHE_OBJECT_EV_CLEARED);
120 fscache_initialise_object(object);
121 goto done;
122
123 /* look up the object metadata on disk */
124 case FSCACHE_OBJECT_LOOKING_UP:
125 fscache_lookup_object(object);
126 goto lookup_transit;
127
128 /* create the object metadata on disk */
129 case FSCACHE_OBJECT_CREATING:
130 fscache_lookup_object(object);
131 goto lookup_transit;
132
133 /* handle an object becoming available; start pending
134 * operations and queue dependent operations for processing */
135 case FSCACHE_OBJECT_AVAILABLE:
136 fscache_object_available(object);
137 goto active_transit;
138
139 /* normal running state */
140 case FSCACHE_OBJECT_ACTIVE:
141 goto active_transit;
142
143 /* Invalidate an object on disk */
144 case FSCACHE_OBJECT_INVALIDATING:
145 clear_bit(FSCACHE_OBJECT_EV_INVALIDATE, &object->events);
146 fscache_stat(&fscache_n_invalidates_run);
147 fscache_stat(&fscache_n_cop_invalidate_object);
148 fscache_invalidate_object(object);
149 fscache_stat_d(&fscache_n_cop_invalidate_object);
150 fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
151 goto active_transit;
152
153 /* update the object metadata on disk */
154 case FSCACHE_OBJECT_UPDATING:
155 clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events);
156 fscache_stat(&fscache_n_updates_run);
157 fscache_stat(&fscache_n_cop_update_object);
158 object->cache->ops->update_object(object);
159 fscache_stat_d(&fscache_n_cop_update_object);
160 goto active_transit;
161
162 /* handle an object dying during lookup or creation */
163 case FSCACHE_OBJECT_LC_DYING:
164 object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
165 fscache_stat(&fscache_n_cop_lookup_complete);
166 object->cache->ops->lookup_complete(object);
167 fscache_stat_d(&fscache_n_cop_lookup_complete);
168
169 spin_lock(&object->lock);
170 object->state = FSCACHE_OBJECT_DYING;
171 cookie = object->cookie;
172 if (cookie) {
173 if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP,
174 &cookie->flags))
175 wake_up_bit(&cookie->flags,
176 FSCACHE_COOKIE_LOOKING_UP);
177 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
178 &cookie->flags))
179 wake_up_bit(&cookie->flags,
180 FSCACHE_COOKIE_CREATING);
181 }
182 spin_unlock(&object->lock);
183
184 fscache_done_parent_op(object);
185
186 /* wait for completion of all active operations on this object
187 * and the death of all child objects of this object */
188 case FSCACHE_OBJECT_DYING:
189 dying:
190 clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events);
191 spin_lock(&object->lock);
192 _debug("dying OBJ%x {%d,%d}",
193 object->debug_id, object->n_ops, object->n_children);
194 if (object->n_ops == 0 && object->n_children == 0) {
195 object->event_mask &=
196 ~(1 << FSCACHE_OBJECT_EV_CLEARED);
197 object->event_mask |=
198 (1 << FSCACHE_OBJECT_EV_WITHDRAW) |
199 (1 << FSCACHE_OBJECT_EV_RETIRE) |
200 (1 << FSCACHE_OBJECT_EV_RELEASE) |
201 (1 << FSCACHE_OBJECT_EV_ERROR);
202 } else {
203 object->event_mask &=
204 ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
205 (1 << FSCACHE_OBJECT_EV_RETIRE) |
206 (1 << FSCACHE_OBJECT_EV_RELEASE) |
207 (1 << FSCACHE_OBJECT_EV_ERROR));
208 object->event_mask |=
209 1 << FSCACHE_OBJECT_EV_CLEARED;
210 }
211 spin_unlock(&object->lock);
212 fscache_enqueue_dependents(object);
213 fscache_start_operations(object);
214 goto terminal_transit;
215
216 /* handle an abort during initialisation */
217 case FSCACHE_OBJECT_ABORT_INIT:
218 _debug("handle abort init %lx", object->events);
219 object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
220
221 spin_lock(&object->lock);
222 fscache_dequeue_object(object);
223
224 object->state = FSCACHE_OBJECT_DYING;
225 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
226 &object->cookie->flags))
227 wake_up_bit(&object->cookie->flags,
228 FSCACHE_COOKIE_CREATING);
229 spin_unlock(&object->lock);
230 goto dying;
231
232 /* handle the netfs releasing an object and possibly marking it
233 * obsolete too */
234 case FSCACHE_OBJECT_RELEASING:
235 case FSCACHE_OBJECT_RECYCLING:
236 object->event_mask &=
237 ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
238 (1 << FSCACHE_OBJECT_EV_RETIRE) |
239 (1 << FSCACHE_OBJECT_EV_RELEASE) |
240 (1 << FSCACHE_OBJECT_EV_ERROR));
241 fscache_release_object(object);
242 spin_lock(&object->lock);
243 object->state = FSCACHE_OBJECT_DEAD;
244 spin_unlock(&object->lock);
245 fscache_stat(&fscache_n_object_dead);
246 goto terminal_transit;
247
248 /* handle the parent cache of this object being withdrawn from
249 * active service */
250 case FSCACHE_OBJECT_WITHDRAWING:
251 object->event_mask &=
252 ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
253 (1 << FSCACHE_OBJECT_EV_RETIRE) |
254 (1 << FSCACHE_OBJECT_EV_RELEASE) |
255 (1 << FSCACHE_OBJECT_EV_ERROR));
256 fscache_withdraw_object(object);
257 spin_lock(&object->lock);
258 object->state = FSCACHE_OBJECT_DEAD;
259 spin_unlock(&object->lock);
260 fscache_stat(&fscache_n_object_dead);
261 goto terminal_transit;
262
263 /* complain about the object being woken up once it is
264 * deceased */
265 case FSCACHE_OBJECT_DEAD:
266 printk(KERN_ERR "FS-Cache:"
267 " Unexpected event in dead state %lx\n",
268 object->events & object->event_mask);
269 BUG();
270
271 default:
272 printk(KERN_ERR "FS-Cache: Unknown object state %u\n",
273 object->state);
274 BUG();
275 }
276
277 /* determine the transition from a lookup state */
278 lookup_transit:
279 event = fls(object->events & object->event_mask) - 1;
280 switch (event) {
281 case FSCACHE_OBJECT_EV_WITHDRAW:
282 case FSCACHE_OBJECT_EV_RETIRE:
283 case FSCACHE_OBJECT_EV_RELEASE:
284 case FSCACHE_OBJECT_EV_ERROR:
285 new_state = FSCACHE_OBJECT_LC_DYING;
286 goto change_state;
287 case FSCACHE_OBJECT_EV_INVALIDATE:
288 new_state = FSCACHE_OBJECT_INVALIDATING;
289 goto change_state;
290 case FSCACHE_OBJECT_EV_REQUEUE:
291 goto done;
292 case -1:
293 goto done; /* sleep until event */
294 default:
295 goto unsupported_event;
296 }
297
298 /* determine the transition from an active state */
299 active_transit:
300 event = fls(object->events & object->event_mask) - 1;
301 switch (event) {
302 case FSCACHE_OBJECT_EV_WITHDRAW:
303 case FSCACHE_OBJECT_EV_RETIRE:
304 case FSCACHE_OBJECT_EV_RELEASE:
305 case FSCACHE_OBJECT_EV_ERROR:
306 new_state = FSCACHE_OBJECT_DYING;
307 goto change_state;
308 case FSCACHE_OBJECT_EV_INVALIDATE:
309 new_state = FSCACHE_OBJECT_INVALIDATING;
310 goto change_state;
311 case FSCACHE_OBJECT_EV_UPDATE:
312 new_state = FSCACHE_OBJECT_UPDATING;
313 goto change_state;
314 case -1:
315 new_state = FSCACHE_OBJECT_ACTIVE;
316 goto change_state; /* sleep until event */
317 default:
318 goto unsupported_event;
319 }
320
321 /* determine the transition from a terminal state */
322 terminal_transit:
323 event = fls(object->events & object->event_mask) - 1;
324 switch (event) {
325 case FSCACHE_OBJECT_EV_WITHDRAW:
326 new_state = FSCACHE_OBJECT_WITHDRAWING;
327 goto change_state;
328 case FSCACHE_OBJECT_EV_RETIRE:
329 new_state = FSCACHE_OBJECT_RECYCLING;
330 goto change_state;
331 case FSCACHE_OBJECT_EV_RELEASE:
332 new_state = FSCACHE_OBJECT_RELEASING;
333 goto change_state;
334 case FSCACHE_OBJECT_EV_ERROR:
335 new_state = FSCACHE_OBJECT_WITHDRAWING;
336 goto change_state;
337 case FSCACHE_OBJECT_EV_CLEARED:
338 new_state = FSCACHE_OBJECT_DYING;
339 goto change_state;
340 case -1:
341 goto done; /* sleep until event */
342 default:
343 goto unsupported_event;
344 }
345
346 change_state:
347 spin_lock(&object->lock);
348 object->state = new_state;
349 spin_unlock(&object->lock);
350
351 done:
352 _leave(" [->%s]", fscache_object_states[object->state]);
353 return;
354
355 unsupported_event:
356 printk(KERN_ERR "FS-Cache:"
357 " Unsupported event %d [%lx/%lx] in state %s\n",
358 event, object->events, object->event_mask,
359 fscache_object_states[object->state]);
360 BUG();
361 }
362
363 /*
364 * execute an object
365 */
366 void fscache_object_work_func(struct work_struct *work)
367 {
368 struct fscache_object *object =
369 container_of(work, struct fscache_object, work);
370 unsigned long start;
371
372 _enter("{OBJ%x}", object->debug_id);
373
374 start = jiffies;
375 fscache_object_state_machine(object);
376 fscache_hist(fscache_objs_histogram, start);
377 if (object->events & object->event_mask)
378 fscache_enqueue_object(object);
379 clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
380 fscache_put_object(object);
381 }
382 EXPORT_SYMBOL(fscache_object_work_func);
383
384 /*
385 * initialise an object
386 * - check the specified object's parent to see if we can make use of it
387 * immediately to do a creation
388 * - we may need to start the process of creating a parent and we need to wait
389 * for the parent's lookup and creation to complete if it's not there yet
390 * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the
391 * leaf-most cookies of the object and all its children
392 */
393 static void fscache_initialise_object(struct fscache_object *object)
394 {
395 struct fscache_object *parent;
396
397 _enter("");
398 ASSERT(object->cookie != NULL);
399 ASSERT(object->cookie->parent != NULL);
400
401 if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) |
402 (1 << FSCACHE_OBJECT_EV_RELEASE) |
403 (1 << FSCACHE_OBJECT_EV_RETIRE) |
404 (1 << FSCACHE_OBJECT_EV_WITHDRAW))) {
405 _debug("abort init %lx", object->events);
406 spin_lock(&object->lock);
407 object->state = FSCACHE_OBJECT_ABORT_INIT;
408 spin_unlock(&object->lock);
409 return;
410 }
411
412 spin_lock(&object->cookie->lock);
413 spin_lock_nested(&object->cookie->parent->lock, 1);
414
415 parent = object->parent;
416 if (!parent) {
417 _debug("no parent");
418 set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
419 } else {
420 spin_lock(&object->lock);
421 spin_lock_nested(&parent->lock, 1);
422 _debug("parent %s", fscache_object_states[parent->state]);
423
424 if (parent->state >= FSCACHE_OBJECT_DYING) {
425 _debug("bad parent");
426 set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
427 } else if (parent->state < FSCACHE_OBJECT_AVAILABLE) {
428 _debug("wait");
429
430 /* we may get woken up in this state by child objects
431 * binding on to us, so we need to make sure we don't
432 * add ourself to the list multiple times */
433 if (list_empty(&object->dep_link)) {
434 fscache_stat(&fscache_n_cop_grab_object);
435 object->cache->ops->grab_object(object);
436 fscache_stat_d(&fscache_n_cop_grab_object);
437 list_add(&object->dep_link,
438 &parent->dependents);
439
440 /* fscache_acquire_non_index_cookie() uses this
441 * to wake the chain up */
442 if (parent->state == FSCACHE_OBJECT_INIT)
443 fscache_enqueue_object(parent);
444 }
445 } else {
446 _debug("go");
447 parent->n_ops++;
448 parent->n_obj_ops++;
449 object->lookup_jif = jiffies;
450 object->state = FSCACHE_OBJECT_LOOKING_UP;
451 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
452 }
453
454 spin_unlock(&parent->lock);
455 spin_unlock(&object->lock);
456 }
457
458 spin_unlock(&object->cookie->parent->lock);
459 spin_unlock(&object->cookie->lock);
460 _leave("");
461 }
462
463 /*
464 * look an object up in the cache from which it was allocated
465 * - we hold an "access lock" on the parent object, so the parent object cannot
466 * be withdrawn by either party till we've finished
467 * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the
468 * leaf-most cookies of the object and all its children
469 */
470 static void fscache_lookup_object(struct fscache_object *object)
471 {
472 struct fscache_cookie *cookie = object->cookie;
473 struct fscache_object *parent;
474 int ret;
475
476 _enter("");
477
478 parent = object->parent;
479 ASSERT(parent != NULL);
480 ASSERTCMP(parent->n_ops, >, 0);
481 ASSERTCMP(parent->n_obj_ops, >, 0);
482
483 /* make sure the parent is still available */
484 ASSERTCMP(parent->state, >=, FSCACHE_OBJECT_AVAILABLE);
485
486 if (parent->state >= FSCACHE_OBJECT_DYING ||
487 test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
488 _debug("unavailable");
489 set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
490 _leave("");
491 return;
492 }
493
494 _debug("LOOKUP \"%s/%s\" in \"%s\"",
495 parent->cookie->def->name, cookie->def->name,
496 object->cache->tag->name);
497
498 fscache_stat(&fscache_n_object_lookups);
499 fscache_stat(&fscache_n_cop_lookup_object);
500 ret = object->cache->ops->lookup_object(object);
501 fscache_stat_d(&fscache_n_cop_lookup_object);
502
503 if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events))
504 set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
505
506 if (ret == -ETIMEDOUT) {
507 /* probably stuck behind another object, so move this one to
508 * the back of the queue */
509 fscache_stat(&fscache_n_object_lookups_timed_out);
510 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
511 }
512
513 _leave("");
514 }
515
516 /**
517 * fscache_object_lookup_negative - Note negative cookie lookup
518 * @object: Object pointing to cookie to mark
519 *
520 * Note negative lookup, permitting those waiting to read data from an already
521 * existing backing object to continue as there's no data for them to read.
522 */
523 void fscache_object_lookup_negative(struct fscache_object *object)
524 {
525 struct fscache_cookie *cookie = object->cookie;
526
527 _enter("{OBJ%x,%s}",
528 object->debug_id, fscache_object_states[object->state]);
529
530 spin_lock(&object->lock);
531 if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
532 fscache_stat(&fscache_n_object_lookups_negative);
533
534 /* transit here to allow write requests to begin stacking up
535 * and read requests to begin returning ENODATA */
536 object->state = FSCACHE_OBJECT_CREATING;
537 spin_unlock(&object->lock);
538
539 set_bit(FSCACHE_COOKIE_PENDING_FILL, &cookie->flags);
540 set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
541
542 _debug("wake up lookup %p", &cookie->flags);
543 smp_mb__before_clear_bit();
544 clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
545 smp_mb__after_clear_bit();
546 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
547 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
548 } else {
549 ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
550 spin_unlock(&object->lock);
551 }
552
553 _leave("");
554 }
555 EXPORT_SYMBOL(fscache_object_lookup_negative);
556
557 /**
558 * fscache_obtained_object - Note successful object lookup or creation
559 * @object: Object pointing to cookie to mark
560 *
561 * Note successful lookup and/or creation, permitting those waiting to write
562 * data to a backing object to continue.
563 *
564 * Note that after calling this, an object's cookie may be relinquished by the
565 * netfs, and so must be accessed with object lock held.
566 */
567 void fscache_obtained_object(struct fscache_object *object)
568 {
569 struct fscache_cookie *cookie = object->cookie;
570
571 _enter("{OBJ%x,%s}",
572 object->debug_id, fscache_object_states[object->state]);
573
574 /* if we were still looking up, then we must have a positive lookup
575 * result, in which case there may be data available */
576 spin_lock(&object->lock);
577 if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
578 fscache_stat(&fscache_n_object_lookups_positive);
579
580 clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
581
582 object->state = FSCACHE_OBJECT_AVAILABLE;
583 spin_unlock(&object->lock);
584
585 smp_mb__before_clear_bit();
586 clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
587 smp_mb__after_clear_bit();
588 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
589 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
590 } else {
591 ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
592 fscache_stat(&fscache_n_object_created);
593
594 object->state = FSCACHE_OBJECT_AVAILABLE;
595 spin_unlock(&object->lock);
596 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
597 smp_wmb();
598 }
599
600 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &cookie->flags))
601 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_CREATING);
602
603 _leave("");
604 }
605 EXPORT_SYMBOL(fscache_obtained_object);
606
607 /*
608 * handle an object that has just become available
609 */
610 static void fscache_object_available(struct fscache_object *object)
611 {
612 _enter("{OBJ%x}", object->debug_id);
613
614 spin_lock(&object->lock);
615
616 if (object->cookie &&
617 test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags))
618 wake_up_bit(&object->cookie->flags, FSCACHE_COOKIE_CREATING);
619
620 fscache_done_parent_op(object);
621 if (object->n_in_progress == 0) {
622 if (object->n_ops > 0) {
623 ASSERTCMP(object->n_ops, >=, object->n_obj_ops);
624 fscache_start_operations(object);
625 } else {
626 ASSERT(list_empty(&object->pending_ops));
627 }
628 }
629 spin_unlock(&object->lock);
630
631 fscache_stat(&fscache_n_cop_lookup_complete);
632 object->cache->ops->lookup_complete(object);
633 fscache_stat_d(&fscache_n_cop_lookup_complete);
634 fscache_enqueue_dependents(object);
635
636 fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif);
637 fscache_stat(&fscache_n_object_avail);
638
639 _leave("");
640 }
641
642 /*
643 * drop an object's attachments
644 */
645 static void fscache_drop_object(struct fscache_object *object)
646 {
647 struct fscache_object *parent = object->parent;
648 struct fscache_cache *cache = object->cache;
649
650 _enter("{OBJ%x,%d}", object->debug_id, object->n_children);
651
652 ASSERTCMP(object->cookie, ==, NULL);
653 ASSERT(hlist_unhashed(&object->cookie_link));
654
655 spin_lock(&cache->object_list_lock);
656 list_del_init(&object->cache_link);
657 spin_unlock(&cache->object_list_lock);
658
659 fscache_stat(&fscache_n_cop_drop_object);
660 cache->ops->drop_object(object);
661 fscache_stat_d(&fscache_n_cop_drop_object);
662
663 if (parent) {
664 _debug("release parent OBJ%x {%d}",
665 parent->debug_id, parent->n_children);
666
667 spin_lock(&parent->lock);
668 parent->n_children--;
669 if (parent->n_children == 0)
670 fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
671 spin_unlock(&parent->lock);
672 object->parent = NULL;
673 }
674
675 /* this just shifts the object release to the work processor */
676 fscache_put_object(object);
677
678 _leave("");
679 }
680
681 /*
682 * release or recycle an object that the netfs has discarded
683 */
684 static void fscache_release_object(struct fscache_object *object)
685 {
686 _enter("");
687
688 fscache_drop_object(object);
689 }
690
691 /*
692 * withdraw an object from active service
693 */
694 static void fscache_withdraw_object(struct fscache_object *object)
695 {
696 struct fscache_cookie *cookie;
697 bool detached;
698
699 _enter("");
700
701 spin_lock(&object->lock);
702 cookie = object->cookie;
703 if (cookie) {
704 /* need to get the cookie lock before the object lock, starting
705 * from the object pointer */
706 atomic_inc(&cookie->usage);
707 spin_unlock(&object->lock);
708
709 detached = false;
710 spin_lock(&cookie->lock);
711 spin_lock(&object->lock);
712
713 if (object->cookie == cookie) {
714 hlist_del_init(&object->cookie_link);
715 object->cookie = NULL;
716 fscache_invalidation_complete(cookie);
717 detached = true;
718 }
719 spin_unlock(&cookie->lock);
720 fscache_cookie_put(cookie);
721 if (detached)
722 fscache_cookie_put(cookie);
723 }
724
725 spin_unlock(&object->lock);
726
727 fscache_drop_object(object);
728 }
729
730 /*
731 * withdraw an object from active service at the behest of the cache
732 * - need break the links to a cached object cookie
733 * - called under two situations:
734 * (1) recycler decides to reclaim an in-use object
735 * (2) a cache is unmounted
736 * - have to take care as the cookie can be being relinquished by the netfs
737 * simultaneously
738 * - the object is pinned by the caller holding a refcount on it
739 */
740 void fscache_withdrawing_object(struct fscache_cache *cache,
741 struct fscache_object *object)
742 {
743 bool enqueue = false;
744
745 _enter(",OBJ%x", object->debug_id);
746
747 spin_lock(&object->lock);
748 if (object->state < FSCACHE_OBJECT_WITHDRAWING) {
749 object->state = FSCACHE_OBJECT_WITHDRAWING;
750 enqueue = true;
751 }
752 spin_unlock(&object->lock);
753
754 if (enqueue)
755 fscache_enqueue_object(object);
756
757 _leave("");
758 }
759
760 /*
761 * get a ref on an object
762 */
763 static int fscache_get_object(struct fscache_object *object)
764 {
765 int ret;
766
767 fscache_stat(&fscache_n_cop_grab_object);
768 ret = object->cache->ops->grab_object(object) ? 0 : -EAGAIN;
769 fscache_stat_d(&fscache_n_cop_grab_object);
770 return ret;
771 }
772
773 /*
774 * discard a ref on a work item
775 */
776 static void fscache_put_object(struct fscache_object *object)
777 {
778 fscache_stat(&fscache_n_cop_put_object);
779 object->cache->ops->put_object(object);
780 fscache_stat_d(&fscache_n_cop_put_object);
781 }
782
783 /*
784 * enqueue an object for metadata-type processing
785 */
786 void fscache_enqueue_object(struct fscache_object *object)
787 {
788 _enter("{OBJ%x}", object->debug_id);
789
790 if (fscache_get_object(object) >= 0) {
791 wait_queue_head_t *cong_wq =
792 &get_cpu_var(fscache_object_cong_wait);
793
794 if (queue_work(fscache_object_wq, &object->work)) {
795 if (fscache_object_congested())
796 wake_up(cong_wq);
797 } else
798 fscache_put_object(object);
799
800 put_cpu_var(fscache_object_cong_wait);
801 }
802 }
803
804 /**
805 * fscache_object_sleep_till_congested - Sleep until object wq is congested
806 * @timoutp: Scheduler sleep timeout
807 *
808 * Allow an object handler to sleep until the object workqueue is congested.
809 *
810 * The caller must set up a wake up event before calling this and must have set
811 * the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own
812 * condition before calling this function as no test is made here.
813 *
814 * %true is returned if the object wq is congested, %false otherwise.
815 */
816 bool fscache_object_sleep_till_congested(signed long *timeoutp)
817 {
818 wait_queue_head_t *cong_wq = &__get_cpu_var(fscache_object_cong_wait);
819 DEFINE_WAIT(wait);
820
821 if (fscache_object_congested())
822 return true;
823
824 add_wait_queue_exclusive(cong_wq, &wait);
825 if (!fscache_object_congested())
826 *timeoutp = schedule_timeout(*timeoutp);
827 finish_wait(cong_wq, &wait);
828
829 return fscache_object_congested();
830 }
831 EXPORT_SYMBOL_GPL(fscache_object_sleep_till_congested);
832
833 /*
834 * enqueue the dependents of an object for metadata-type processing
835 * - the caller must hold the object's lock
836 * - this may cause an already locked object to wind up being processed again
837 */
838 static void fscache_enqueue_dependents(struct fscache_object *object)
839 {
840 struct fscache_object *dep;
841
842 _enter("{OBJ%x}", object->debug_id);
843
844 if (list_empty(&object->dependents))
845 return;
846
847 spin_lock(&object->lock);
848
849 while (!list_empty(&object->dependents)) {
850 dep = list_entry(object->dependents.next,
851 struct fscache_object, dep_link);
852 list_del_init(&dep->dep_link);
853
854
855 /* sort onto appropriate lists */
856 fscache_enqueue_object(dep);
857 fscache_put_object(dep);
858
859 if (!list_empty(&object->dependents))
860 cond_resched_lock(&object->lock);
861 }
862
863 spin_unlock(&object->lock);
864 }
865
866 /*
867 * remove an object from whatever queue it's waiting on
868 * - the caller must hold object->lock
869 */
870 void fscache_dequeue_object(struct fscache_object *object)
871 {
872 _enter("{OBJ%x}", object->debug_id);
873
874 if (!list_empty(&object->dep_link)) {
875 spin_lock(&object->parent->lock);
876 list_del_init(&object->dep_link);
877 spin_unlock(&object->parent->lock);
878 }
879
880 _leave("");
881 }
882
883 /**
884 * fscache_check_aux - Ask the netfs whether an object on disk is still valid
885 * @object: The object to ask about
886 * @data: The auxiliary data for the object
887 * @datalen: The size of the auxiliary data
888 *
889 * This function consults the netfs about the coherency state of an object
890 */
891 enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
892 const void *data, uint16_t datalen)
893 {
894 enum fscache_checkaux result;
895
896 if (!object->cookie->def->check_aux) {
897 fscache_stat(&fscache_n_checkaux_none);
898 return FSCACHE_CHECKAUX_OKAY;
899 }
900
901 result = object->cookie->def->check_aux(object->cookie->netfs_data,
902 data, datalen);
903 switch (result) {
904 /* entry okay as is */
905 case FSCACHE_CHECKAUX_OKAY:
906 fscache_stat(&fscache_n_checkaux_okay);
907 break;
908
909 /* entry requires update */
910 case FSCACHE_CHECKAUX_NEEDS_UPDATE:
911 fscache_stat(&fscache_n_checkaux_update);
912 break;
913
914 /* entry requires deletion */
915 case FSCACHE_CHECKAUX_OBSOLETE:
916 fscache_stat(&fscache_n_checkaux_obsolete);
917 break;
918
919 default:
920 BUG();
921 }
922
923 return result;
924 }
925 EXPORT_SYMBOL(fscache_check_aux);
926
927 /*
928 * Asynchronously invalidate an object.
929 */
930 static void fscache_invalidate_object(struct fscache_object *object)
931 {
932 struct fscache_operation *op;
933 struct fscache_cookie *cookie = object->cookie;
934
935 _enter("{OBJ%x}", object->debug_id);
936
937 /* Reject any new read/write ops and abort any that are pending. */
938 fscache_invalidate_writes(cookie);
939 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
940 fscache_cancel_all_ops(object);
941
942 /* Now we have to wait for in-progress reads and writes */
943 op = kzalloc(sizeof(*op), GFP_KERNEL);
944 if (!op) {
945 fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
946 _leave(" [ENOMEM]");
947 return;
948 }
949
950 fscache_operation_init(op, object->cache->ops->invalidate_object, NULL);
951 op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE);
952
953 spin_lock(&cookie->lock);
954 if (fscache_submit_exclusive_op(object, op) < 0)
955 goto submit_op_failed;
956 spin_unlock(&cookie->lock);
957 fscache_put_operation(op);
958
959 /* Once we've completed the invalidation, we know there will be no data
960 * stored in the cache and thus we can reinstate the data-check-skip
961 * optimisation.
962 */
963 set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
964
965 /* We can allow read and write requests to come in once again. They'll
966 * queue up behind our exclusive invalidation operation.
967 */
968 fscache_invalidation_complete(cookie);
969 _leave("");
970 return;
971
972 submit_op_failed:
973 spin_unlock(&cookie->lock);
974 kfree(op);
975 fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
976 _leave(" [EIO]");
977 }
CRIS linux kernel tree