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