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-rw-r--r--fs/fscache/object.c810
1 files changed, 810 insertions, 0 deletions
diff --git a/fs/fscache/object.c b/fs/fscache/object.c
new file mode 100644
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+++ b/fs/fscache/object.c
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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 "internal.h"
18
19const char *fscache_object_states[] = {
20 [FSCACHE_OBJECT_INIT] = "OBJECT_INIT",
21 [FSCACHE_OBJECT_LOOKING_UP] = "OBJECT_LOOKING_UP",
22 [FSCACHE_OBJECT_CREATING] = "OBJECT_CREATING",
23 [FSCACHE_OBJECT_AVAILABLE] = "OBJECT_AVAILABLE",
24 [FSCACHE_OBJECT_ACTIVE] = "OBJECT_ACTIVE",
25 [FSCACHE_OBJECT_UPDATING] = "OBJECT_UPDATING",
26 [FSCACHE_OBJECT_DYING] = "OBJECT_DYING",
27 [FSCACHE_OBJECT_LC_DYING] = "OBJECT_LC_DYING",
28 [FSCACHE_OBJECT_ABORT_INIT] = "OBJECT_ABORT_INIT",
29 [FSCACHE_OBJECT_RELEASING] = "OBJECT_RELEASING",
30 [FSCACHE_OBJECT_RECYCLING] = "OBJECT_RECYCLING",
31 [FSCACHE_OBJECT_WITHDRAWING] = "OBJECT_WITHDRAWING",
32 [FSCACHE_OBJECT_DEAD] = "OBJECT_DEAD",
33};
34EXPORT_SYMBOL(fscache_object_states);
35
36static void fscache_object_slow_work_put_ref(struct slow_work *);
37static int fscache_object_slow_work_get_ref(struct slow_work *);
38static void fscache_object_slow_work_execute(struct slow_work *);
39static void fscache_initialise_object(struct fscache_object *);
40static void fscache_lookup_object(struct fscache_object *);
41static void fscache_object_available(struct fscache_object *);
42static void fscache_release_object(struct fscache_object *);
43static void fscache_withdraw_object(struct fscache_object *);
44static void fscache_enqueue_dependents(struct fscache_object *);
45static void fscache_dequeue_object(struct fscache_object *);
46
47const struct slow_work_ops fscache_object_slow_work_ops = {
48 .get_ref = fscache_object_slow_work_get_ref,
49 .put_ref = fscache_object_slow_work_put_ref,
50 .execute = fscache_object_slow_work_execute,
51};
52EXPORT_SYMBOL(fscache_object_slow_work_ops);
53
54/*
55 * we need to notify the parent when an op completes that we had outstanding
56 * upon it
57 */
58static inline void fscache_done_parent_op(struct fscache_object *object)
59{
60 struct fscache_object *parent = object->parent;
61
62 _enter("OBJ%x {OBJ%x,%x}",
63 object->debug_id, parent->debug_id, parent->n_ops);
64
65 spin_lock_nested(&parent->lock, 1);
66 parent->n_ops--;
67 parent->n_obj_ops--;
68 if (parent->n_ops == 0)
69 fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
70 spin_unlock(&parent->lock);
71}
72
73/*
74 * process events that have been sent to an object's state machine
75 * - initiates parent lookup
76 * - does object lookup
77 * - does object creation
78 * - does object recycling and retirement
79 * - does object withdrawal
80 */
81static void fscache_object_state_machine(struct fscache_object *object)
82{
83 enum fscache_object_state new_state;
84
85 ASSERT(object != NULL);
86
87 _enter("{OBJ%x,%s,%lx}",
88 object->debug_id, fscache_object_states[object->state],
89 object->events);
90
91 switch (object->state) {
92 /* wait for the parent object to become ready */
93 case FSCACHE_OBJECT_INIT:
94 object->event_mask =
95 ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED);
96 fscache_initialise_object(object);
97 goto done;
98
99 /* look up the object metadata on disk */
100 case FSCACHE_OBJECT_LOOKING_UP:
101 fscache_lookup_object(object);
102 goto lookup_transit;
103
104 /* create the object metadata on disk */
105 case FSCACHE_OBJECT_CREATING:
106 fscache_lookup_object(object);
107 goto lookup_transit;
108
109 /* handle an object becoming available; start pending
110 * operations and queue dependent operations for processing */
111 case FSCACHE_OBJECT_AVAILABLE:
112 fscache_object_available(object);
113 goto active_transit;
114
115 /* normal running state */
116 case FSCACHE_OBJECT_ACTIVE:
117 goto active_transit;
118
119 /* update the object metadata on disk */
120 case FSCACHE_OBJECT_UPDATING:
121 clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events);
122 fscache_stat(&fscache_n_updates_run);
123 object->cache->ops->update_object(object);
124 goto active_transit;
125
126 /* handle an object dying during lookup or creation */
127 case FSCACHE_OBJECT_LC_DYING:
128 object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
129 object->cache->ops->lookup_complete(object);
130
131 spin_lock(&object->lock);
132 object->state = FSCACHE_OBJECT_DYING;
133 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
134 &object->cookie->flags))
135 wake_up_bit(&object->cookie->flags,
136 FSCACHE_COOKIE_CREATING);
137 spin_unlock(&object->lock);
138
139 fscache_done_parent_op(object);
140
141 /* wait for completion of all active operations on this object
142 * and the death of all child objects of this object */
143 case FSCACHE_OBJECT_DYING:
144 dying:
145 clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events);
146 spin_lock(&object->lock);
147 _debug("dying OBJ%x {%d,%d}",
148 object->debug_id, object->n_ops, object->n_children);
149 if (object->n_ops == 0 && object->n_children == 0) {
150 object->event_mask &=
151 ~(1 << FSCACHE_OBJECT_EV_CLEARED);
152 object->event_mask |=
153 (1 << FSCACHE_OBJECT_EV_WITHDRAW) |
154 (1 << FSCACHE_OBJECT_EV_RETIRE) |
155 (1 << FSCACHE_OBJECT_EV_RELEASE) |
156 (1 << FSCACHE_OBJECT_EV_ERROR);
157 } else {
158 object->event_mask &=
159 ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
160 (1 << FSCACHE_OBJECT_EV_RETIRE) |
161 (1 << FSCACHE_OBJECT_EV_RELEASE) |
162 (1 << FSCACHE_OBJECT_EV_ERROR));
163 object->event_mask |=
164 1 << FSCACHE_OBJECT_EV_CLEARED;
165 }
166 spin_unlock(&object->lock);
167 fscache_enqueue_dependents(object);
168 goto terminal_transit;
169
170 /* handle an abort during initialisation */
171 case FSCACHE_OBJECT_ABORT_INIT:
172 _debug("handle abort init %lx", object->events);
173 object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
174
175 spin_lock(&object->lock);
176 fscache_dequeue_object(object);
177
178 object->state = FSCACHE_OBJECT_DYING;
179 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
180 &object->cookie->flags))
181 wake_up_bit(&object->cookie->flags,
182 FSCACHE_COOKIE_CREATING);
183 spin_unlock(&object->lock);
184 goto dying;
185
186 /* handle the netfs releasing an object and possibly marking it
187 * obsolete too */
188 case FSCACHE_OBJECT_RELEASING:
189 case FSCACHE_OBJECT_RECYCLING:
190 object->event_mask &=
191 ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
192 (1 << FSCACHE_OBJECT_EV_RETIRE) |
193 (1 << FSCACHE_OBJECT_EV_RELEASE) |
194 (1 << FSCACHE_OBJECT_EV_ERROR));
195 fscache_release_object(object);
196 spin_lock(&object->lock);
197 object->state = FSCACHE_OBJECT_DEAD;
198 spin_unlock(&object->lock);
199 fscache_stat(&fscache_n_object_dead);
200 goto terminal_transit;
201
202 /* handle the parent cache of this object being withdrawn from
203 * active service */
204 case FSCACHE_OBJECT_WITHDRAWING:
205 object->event_mask &=
206 ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
207 (1 << FSCACHE_OBJECT_EV_RETIRE) |
208 (1 << FSCACHE_OBJECT_EV_RELEASE) |
209 (1 << FSCACHE_OBJECT_EV_ERROR));
210 fscache_withdraw_object(object);
211 spin_lock(&object->lock);
212 object->state = FSCACHE_OBJECT_DEAD;
213 spin_unlock(&object->lock);
214 fscache_stat(&fscache_n_object_dead);
215 goto terminal_transit;
216
217 /* complain about the object being woken up once it is
218 * deceased */
219 case FSCACHE_OBJECT_DEAD:
220 printk(KERN_ERR "FS-Cache:"
221 " Unexpected event in dead state %lx\n",
222 object->events & object->event_mask);
223 BUG();
224
225 default:
226 printk(KERN_ERR "FS-Cache: Unknown object state %u\n",
227 object->state);
228 BUG();
229 }
230
231 /* determine the transition from a lookup state */
232lookup_transit:
233 switch (fls(object->events & object->event_mask) - 1) {
234 case FSCACHE_OBJECT_EV_WITHDRAW:
235 case FSCACHE_OBJECT_EV_RETIRE:
236 case FSCACHE_OBJECT_EV_RELEASE:
237 case FSCACHE_OBJECT_EV_ERROR:
238 new_state = FSCACHE_OBJECT_LC_DYING;
239 goto change_state;
240 case FSCACHE_OBJECT_EV_REQUEUE:
241 goto done;
242 case -1:
243 goto done; /* sleep until event */
244 default:
245 goto unsupported_event;
246 }
247
248 /* determine the transition from an active state */
249active_transit:
250 switch (fls(object->events & object->event_mask) - 1) {
251 case FSCACHE_OBJECT_EV_WITHDRAW:
252 case FSCACHE_OBJECT_EV_RETIRE:
253 case FSCACHE_OBJECT_EV_RELEASE:
254 case FSCACHE_OBJECT_EV_ERROR:
255 new_state = FSCACHE_OBJECT_DYING;
256 goto change_state;
257 case FSCACHE_OBJECT_EV_UPDATE:
258 new_state = FSCACHE_OBJECT_UPDATING;
259 goto change_state;
260 case -1:
261 new_state = FSCACHE_OBJECT_ACTIVE;
262 goto change_state; /* sleep until event */
263 default:
264 goto unsupported_event;
265 }
266
267 /* determine the transition from a terminal state */
268terminal_transit:
269 switch (fls(object->events & object->event_mask) - 1) {
270 case FSCACHE_OBJECT_EV_WITHDRAW:
271 new_state = FSCACHE_OBJECT_WITHDRAWING;
272 goto change_state;
273 case FSCACHE_OBJECT_EV_RETIRE:
274 new_state = FSCACHE_OBJECT_RECYCLING;
275 goto change_state;
276 case FSCACHE_OBJECT_EV_RELEASE:
277 new_state = FSCACHE_OBJECT_RELEASING;
278 goto change_state;
279 case FSCACHE_OBJECT_EV_ERROR:
280 new_state = FSCACHE_OBJECT_WITHDRAWING;
281 goto change_state;
282 case FSCACHE_OBJECT_EV_CLEARED:
283 new_state = FSCACHE_OBJECT_DYING;
284 goto change_state;
285 case -1:
286 goto done; /* sleep until event */
287 default:
288 goto unsupported_event;
289 }
290
291change_state:
292 spin_lock(&object->lock);
293 object->state = new_state;
294 spin_unlock(&object->lock);
295
296done:
297 _leave(" [->%s]", fscache_object_states[object->state]);
298 return;
299
300unsupported_event:
301 printk(KERN_ERR "FS-Cache:"
302 " Unsupported event %lx [mask %lx] in state %s\n",
303 object->events, object->event_mask,
304 fscache_object_states[object->state]);
305 BUG();
306}
307
308/*
309 * execute an object
310 */
311static void fscache_object_slow_work_execute(struct slow_work *work)
312{
313 struct fscache_object *object =
314 container_of(work, struct fscache_object, work);
315 unsigned long start;
316
317 _enter("{OBJ%x}", object->debug_id);
318
319 clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
320
321 start = jiffies;
322 fscache_object_state_machine(object);
323 fscache_hist(fscache_objs_histogram, start);
324 if (object->events & object->event_mask)
325 fscache_enqueue_object(object);
326}
327
328/*
329 * initialise an object
330 * - check the specified object's parent to see if we can make use of it
331 * immediately to do a creation
332 * - we may need to start the process of creating a parent and we need to wait
333 * for the parent's lookup and creation to complete if it's not there yet
334 * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the
335 * leaf-most cookies of the object and all its children
336 */
337static void fscache_initialise_object(struct fscache_object *object)
338{
339 struct fscache_object *parent;
340
341 _enter("");
342 ASSERT(object->cookie != NULL);
343 ASSERT(object->cookie->parent != NULL);
344 ASSERT(list_empty(&object->work.link));
345
346 if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) |
347 (1 << FSCACHE_OBJECT_EV_RELEASE) |
348 (1 << FSCACHE_OBJECT_EV_RETIRE) |
349 (1 << FSCACHE_OBJECT_EV_WITHDRAW))) {
350 _debug("abort init %lx", object->events);
351 spin_lock(&object->lock);
352 object->state = FSCACHE_OBJECT_ABORT_INIT;
353 spin_unlock(&object->lock);
354 return;
355 }
356
357 spin_lock(&object->cookie->lock);
358 spin_lock_nested(&object->cookie->parent->lock, 1);
359
360 parent = object->parent;
361 if (!parent) {
362 _debug("no parent");
363 set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
364 } else {
365 spin_lock(&object->lock);
366 spin_lock_nested(&parent->lock, 1);
367 _debug("parent %s", fscache_object_states[parent->state]);
368
369 if (parent->state >= FSCACHE_OBJECT_DYING) {
370 _debug("bad parent");
371 set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
372 } else if (parent->state < FSCACHE_OBJECT_AVAILABLE) {
373 _debug("wait");
374
375 /* we may get woken up in this state by child objects
376 * binding on to us, so we need to make sure we don't
377 * add ourself to the list multiple times */
378 if (list_empty(&object->dep_link)) {
379 object->cache->ops->grab_object(object);
380 list_add(&object->dep_link,
381 &parent->dependents);
382
383 /* fscache_acquire_non_index_cookie() uses this
384 * to wake the chain up */
385 if (parent->state == FSCACHE_OBJECT_INIT)
386 fscache_enqueue_object(parent);
387 }
388 } else {
389 _debug("go");
390 parent->n_ops++;
391 parent->n_obj_ops++;
392 object->lookup_jif = jiffies;
393 object->state = FSCACHE_OBJECT_LOOKING_UP;
394 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
395 }
396
397 spin_unlock(&parent->lock);
398 spin_unlock(&object->lock);
399 }
400
401 spin_unlock(&object->cookie->parent->lock);
402 spin_unlock(&object->cookie->lock);
403 _leave("");
404}
405
406/*
407 * look an object up in the cache from which it was allocated
408 * - we hold an "access lock" on the parent object, so the parent object cannot
409 * be withdrawn by either party till we've finished
410 * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the
411 * leaf-most cookies of the object and all its children
412 */
413static void fscache_lookup_object(struct fscache_object *object)
414{
415 struct fscache_cookie *cookie = object->cookie;
416 struct fscache_object *parent;
417
418 _enter("");
419
420 parent = object->parent;
421 ASSERT(parent != NULL);
422 ASSERTCMP(parent->n_ops, >, 0);
423 ASSERTCMP(parent->n_obj_ops, >, 0);
424
425 /* make sure the parent is still available */
426 ASSERTCMP(parent->state, >=, FSCACHE_OBJECT_AVAILABLE);
427
428 if (parent->state >= FSCACHE_OBJECT_DYING ||
429 test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
430 _debug("unavailable");
431 set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
432 _leave("");
433 return;
434 }
435
436 _debug("LOOKUP \"%s/%s\" in \"%s\"",
437 parent->cookie->def->name, cookie->def->name,
438 object->cache->tag->name);
439
440 fscache_stat(&fscache_n_object_lookups);
441 object->cache->ops->lookup_object(object);
442
443 if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events))
444 set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
445
446 _leave("");
447}
448
449/**
450 * fscache_object_lookup_negative - Note negative cookie lookup
451 * @object: Object pointing to cookie to mark
452 *
453 * Note negative lookup, permitting those waiting to read data from an already
454 * existing backing object to continue as there's no data for them to read.
455 */
456void fscache_object_lookup_negative(struct fscache_object *object)
457{
458 struct fscache_cookie *cookie = object->cookie;
459
460 _enter("{OBJ%x,%s}",
461 object->debug_id, fscache_object_states[object->state]);
462
463 spin_lock(&object->lock);
464 if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
465 fscache_stat(&fscache_n_object_lookups_negative);
466
467 /* transit here to allow write requests to begin stacking up
468 * and read requests to begin returning ENODATA */
469 object->state = FSCACHE_OBJECT_CREATING;
470 spin_unlock(&object->lock);
471
472 set_bit(FSCACHE_COOKIE_PENDING_FILL, &cookie->flags);
473 set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
474
475 _debug("wake up lookup %p", &cookie->flags);
476 smp_mb__before_clear_bit();
477 clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
478 smp_mb__after_clear_bit();
479 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
480 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
481 } else {
482 ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
483 spin_unlock(&object->lock);
484 }
485
486 _leave("");
487}
488EXPORT_SYMBOL(fscache_object_lookup_negative);
489
490/**
491 * fscache_obtained_object - Note successful object lookup or creation
492 * @object: Object pointing to cookie to mark
493 *
494 * Note successful lookup and/or creation, permitting those waiting to write
495 * data to a backing object to continue.
496 *
497 * Note that after calling this, an object's cookie may be relinquished by the
498 * netfs, and so must be accessed with object lock held.
499 */
500void fscache_obtained_object(struct fscache_object *object)
501{
502 struct fscache_cookie *cookie = object->cookie;
503
504 _enter("{OBJ%x,%s}",
505 object->debug_id, fscache_object_states[object->state]);
506
507 /* if we were still looking up, then we must have a positive lookup
508 * result, in which case there may be data available */
509 spin_lock(&object->lock);
510 if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
511 fscache_stat(&fscache_n_object_lookups_positive);
512
513 clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
514
515 object->state = FSCACHE_OBJECT_AVAILABLE;
516 spin_unlock(&object->lock);
517
518 smp_mb__before_clear_bit();
519 clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
520 smp_mb__after_clear_bit();
521 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
522 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
523 } else {
524 ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
525 fscache_stat(&fscache_n_object_created);
526
527 object->state = FSCACHE_OBJECT_AVAILABLE;
528 spin_unlock(&object->lock);
529 set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
530 smp_wmb();
531 }
532
533 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &cookie->flags))
534 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_CREATING);
535
536 _leave("");
537}
538EXPORT_SYMBOL(fscache_obtained_object);
539
540/*
541 * handle an object that has just become available
542 */
543static void fscache_object_available(struct fscache_object *object)
544{
545 _enter("{OBJ%x}", object->debug_id);
546
547 spin_lock(&object->lock);
548
549 if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags))
550 wake_up_bit(&object->cookie->flags, FSCACHE_COOKIE_CREATING);
551
552 fscache_done_parent_op(object);
553 if (object->n_in_progress == 0) {
554 if (object->n_ops > 0) {
555 ASSERTCMP(object->n_ops, >=, object->n_obj_ops);
556 ASSERTIF(object->n_ops > object->n_obj_ops,
557 !list_empty(&object->pending_ops));
558 fscache_start_operations(object);
559 } else {
560 ASSERT(list_empty(&object->pending_ops));
561 }
562 }
563 spin_unlock(&object->lock);
564
565 object->cache->ops->lookup_complete(object);
566 fscache_enqueue_dependents(object);
567
568 fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif);
569 fscache_stat(&fscache_n_object_avail);
570
571 _leave("");
572}
573
574/*
575 * drop an object's attachments
576 */
577static void fscache_drop_object(struct fscache_object *object)
578{
579 struct fscache_object *parent = object->parent;
580 struct fscache_cache *cache = object->cache;
581
582 _enter("{OBJ%x,%d}", object->debug_id, object->n_children);
583
584 spin_lock(&cache->object_list_lock);
585 list_del_init(&object->cache_link);
586 spin_unlock(&cache->object_list_lock);
587
588 cache->ops->drop_object(object);
589
590 if (parent) {
591 _debug("release parent OBJ%x {%d}",
592 parent->debug_id, parent->n_children);
593
594 spin_lock(&parent->lock);
595 parent->n_children--;
596 if (parent->n_children == 0)
597 fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
598 spin_unlock(&parent->lock);
599 object->parent = NULL;
600 }
601
602 /* this just shifts the object release to the slow work processor */
603 object->cache->ops->put_object(object);
604
605 _leave("");
606}
607
608/*
609 * release or recycle an object that the netfs has discarded
610 */
611static void fscache_release_object(struct fscache_object *object)
612{
613 _enter("");
614
615 fscache_drop_object(object);
616}
617
618/*
619 * withdraw an object from active service
620 */
621static void fscache_withdraw_object(struct fscache_object *object)
622{
623 struct fscache_cookie *cookie;
624 bool detached;
625
626 _enter("");
627
628 spin_lock(&object->lock);
629 cookie = object->cookie;
630 if (cookie) {
631 /* need to get the cookie lock before the object lock, starting
632 * from the object pointer */
633 atomic_inc(&cookie->usage);
634 spin_unlock(&object->lock);
635
636 detached = false;
637 spin_lock(&cookie->lock);
638 spin_lock(&object->lock);
639
640 if (object->cookie == cookie) {
641 hlist_del_init(&object->cookie_link);
642 object->cookie = NULL;
643 detached = true;
644 }
645 spin_unlock(&cookie->lock);
646 fscache_cookie_put(cookie);
647 if (detached)
648 fscache_cookie_put(cookie);
649 }
650
651 spin_unlock(&object->lock);
652
653 fscache_drop_object(object);
654}
655
656/*
657 * withdraw an object from active service at the behest of the cache
658 * - need break the links to a cached object cookie
659 * - called under two situations:
660 * (1) recycler decides to reclaim an in-use object
661 * (2) a cache is unmounted
662 * - have to take care as the cookie can be being relinquished by the netfs
663 * simultaneously
664 * - the object is pinned by the caller holding a refcount on it
665 */
666void fscache_withdrawing_object(struct fscache_cache *cache,
667 struct fscache_object *object)
668{
669 bool enqueue = false;
670
671 _enter(",OBJ%x", object->debug_id);
672
673 spin_lock(&object->lock);
674 if (object->state < FSCACHE_OBJECT_WITHDRAWING) {
675 object->state = FSCACHE_OBJECT_WITHDRAWING;
676 enqueue = true;
677 }
678 spin_unlock(&object->lock);
679
680 if (enqueue)
681 fscache_enqueue_object(object);
682
683 _leave("");
684}
685
686/*
687 * allow the slow work item processor to get a ref on an object
688 */
689static int fscache_object_slow_work_get_ref(struct slow_work *work)
690{
691 struct fscache_object *object =
692 container_of(work, struct fscache_object, work);
693
694 return object->cache->ops->grab_object(object) ? 0 : -EAGAIN;
695}
696
697/*
698 * allow the slow work item processor to discard a ref on a work item
699 */
700static void fscache_object_slow_work_put_ref(struct slow_work *work)
701{
702 struct fscache_object *object =
703 container_of(work, struct fscache_object, work);
704
705 return object->cache->ops->put_object(object);
706}
707
708/*
709 * enqueue an object for metadata-type processing
710 */
711void fscache_enqueue_object(struct fscache_object *object)
712{
713 _enter("{OBJ%x}", object->debug_id);
714
715 slow_work_enqueue(&object->work);
716}
717
718/*
719 * enqueue the dependents of an object for metadata-type processing
720 * - the caller must hold the object's lock
721 * - this may cause an already locked object to wind up being processed again
722 */
723static void fscache_enqueue_dependents(struct fscache_object *object)
724{
725 struct fscache_object *dep;
726
727 _enter("{OBJ%x}", object->debug_id);
728
729 if (list_empty(&object->dependents))
730 return;
731
732 spin_lock(&object->lock);
733
734 while (!list_empty(&object->dependents)) {
735 dep = list_entry(object->dependents.next,
736 struct fscache_object, dep_link);
737 list_del_init(&dep->dep_link);
738
739
740 /* sort onto appropriate lists */
741 fscache_enqueue_object(dep);
742 dep->cache->ops->put_object(dep);
743
744 if (!list_empty(&object->dependents))
745 cond_resched_lock(&object->lock);
746 }
747
748 spin_unlock(&object->lock);
749}
750
751/*
752 * remove an object from whatever queue it's waiting on
753 * - the caller must hold object->lock
754 */
755void fscache_dequeue_object(struct fscache_object *object)
756{
757 _enter("{OBJ%x}", object->debug_id);
758
759 if (!list_empty(&object->dep_link)) {
760 spin_lock(&object->parent->lock);
761 list_del_init(&object->dep_link);
762 spin_unlock(&object->parent->lock);
763 }
764
765 _leave("");
766}
767
768/**
769 * fscache_check_aux - Ask the netfs whether an object on disk is still valid
770 * @object: The object to ask about
771 * @data: The auxiliary data for the object
772 * @datalen: The size of the auxiliary data
773 *
774 * This function consults the netfs about the coherency state of an object
775 */
776enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
777 const void *data, uint16_t datalen)
778{
779 enum fscache_checkaux result;
780
781 if (!object->cookie->def->check_aux) {
782 fscache_stat(&fscache_n_checkaux_none);
783 return FSCACHE_CHECKAUX_OKAY;
784 }
785
786 result = object->cookie->def->check_aux(object->cookie->netfs_data,
787 data, datalen);
788 switch (result) {
789 /* entry okay as is */
790 case FSCACHE_CHECKAUX_OKAY:
791 fscache_stat(&fscache_n_checkaux_okay);
792 break;
793
794 /* entry requires update */
795 case FSCACHE_CHECKAUX_NEEDS_UPDATE:
796 fscache_stat(&fscache_n_checkaux_update);
797 break;
798
799 /* entry requires deletion */
800 case FSCACHE_CHECKAUX_OBSOLETE:
801 fscache_stat(&fscache_n_checkaux_obsolete);
802 break;
803
804 default:
805 BUG();
806 }
807
808 return result;
809}
810EXPORT_SYMBOL(fscache_check_aux);
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-19 08:02:54 -0500