1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* netfs cookie management
3 *
4 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * See Documentation/filesystems/caching/netfs-api.txt for more information on
8 * the netfs API.
9 */
10
11 #define FSCACHE_DEBUG_LEVEL COOKIE
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include "internal.h"
15
16 struct kmem_cache *fscache_cookie_jar;
17
18 static atomic_t fscache_object_debug_id = ATOMIC_INIT(0);
19
20 #define fscache_cookie_hash_shift 15
21 static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
22
23 static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie,
24 loff_t object_size);
25 static int fscache_alloc_object(struct fscache_cache *cache,
26 struct fscache_cookie *cookie);
27 static int fscache_attach_object(struct fscache_cookie *cookie,
28 struct fscache_object *object);
29
fscache_print_cookie(struct fscache_cookie * cookie,char prefix)30 static void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
31 {
32 struct hlist_node *object;
33 const u8 *k;
34 unsigned loop;
35
36 pr_err("%c-cookie c=%p [p=%p fl=%lx nc=%u na=%u]\n",
37 prefix, cookie, cookie->parent, cookie->flags,
38 atomic_read(&cookie->n_children),
39 atomic_read(&cookie->n_active));
40 pr_err("%c-cookie d=%p n=%p\n",
41 prefix, cookie->def, cookie->netfs_data);
42
43 object = READ_ONCE(cookie->backing_objects.first);
44 if (object)
45 pr_err("%c-cookie o=%p\n",
46 prefix, hlist_entry(object, struct fscache_object, cookie_link));
47
48 pr_err("%c-key=[%u] '", prefix, cookie->key_len);
49 k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
50 cookie->inline_key : cookie->key;
51 for (loop = 0; loop < cookie->key_len; loop++)
52 pr_cont("%02x", k[loop]);
53 pr_cont("'\n");
54 }
55
fscache_free_cookie(struct fscache_cookie * cookie)56 void fscache_free_cookie(struct fscache_cookie *cookie)
57 {
58 if (cookie) {
59 BUG_ON(!hlist_empty(&cookie->backing_objects));
60 if (cookie->aux_len > sizeof(cookie->inline_aux))
61 kfree(cookie->aux);
62 if (cookie->key_len > sizeof(cookie->inline_key))
63 kfree(cookie->key);
64 kmem_cache_free(fscache_cookie_jar, cookie);
65 }
66 }
67
68 /*
69 * Set the index key in a cookie. The cookie struct has space for a 16-byte
70 * key plus length and hash, but if that's not big enough, it's instead a
71 * pointer to a buffer containing 3 bytes of hash, 1 byte of length and then
72 * the key data.
73 */
fscache_set_key(struct fscache_cookie * cookie,const void * index_key,size_t index_key_len)74 static int fscache_set_key(struct fscache_cookie *cookie,
75 const void *index_key, size_t index_key_len)
76 {
77 unsigned long long h;
78 u32 *buf;
79 int bufs;
80 int i;
81
82 bufs = DIV_ROUND_UP(index_key_len, sizeof(*buf));
83
84 if (index_key_len > sizeof(cookie->inline_key)) {
85 buf = kcalloc(bufs, sizeof(*buf), GFP_KERNEL);
86 if (!buf)
87 return -ENOMEM;
88 cookie->key = buf;
89 } else {
90 buf = (u32 *)cookie->inline_key;
91 }
92
93 memcpy(buf, index_key, index_key_len);
94
95 /* Calculate a hash and combine this with the length in the first word
96 * or first half word
97 */
98 h = (unsigned long)cookie->parent;
99 h += index_key_len + cookie->type;
100
101 for (i = 0; i < bufs; i++)
102 h += buf[i];
103
104 cookie->key_hash = h ^ (h >> 32);
105 return 0;
106 }
107
fscache_compare_cookie(const struct fscache_cookie * a,const struct fscache_cookie * b)108 static long fscache_compare_cookie(const struct fscache_cookie *a,
109 const struct fscache_cookie *b)
110 {
111 const void *ka, *kb;
112
113 if (a->key_hash != b->key_hash)
114 return (long)a->key_hash - (long)b->key_hash;
115 if (a->parent != b->parent)
116 return (long)a->parent - (long)b->parent;
117 if (a->key_len != b->key_len)
118 return (long)a->key_len - (long)b->key_len;
119 if (a->type != b->type)
120 return (long)a->type - (long)b->type;
121
122 if (a->key_len <= sizeof(a->inline_key)) {
123 ka = &a->inline_key;
124 kb = &b->inline_key;
125 } else {
126 ka = a->key;
127 kb = b->key;
128 }
129 return memcmp(ka, kb, a->key_len);
130 }
131
132 /*
133 * Allocate a cookie.
134 */
fscache_alloc_cookie(struct fscache_cookie * parent,const struct fscache_cookie_def * def,const void * index_key,size_t index_key_len,const void * aux_data,size_t aux_data_len,void * netfs_data,loff_t object_size)135 struct fscache_cookie *fscache_alloc_cookie(
136 struct fscache_cookie *parent,
137 const struct fscache_cookie_def *def,
138 const void *index_key, size_t index_key_len,
139 const void *aux_data, size_t aux_data_len,
140 void *netfs_data,
141 loff_t object_size)
142 {
143 struct fscache_cookie *cookie;
144
145 /* allocate and initialise a cookie */
146 cookie = kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
147 if (!cookie)
148 return NULL;
149
150 cookie->key_len = index_key_len;
151 cookie->aux_len = aux_data_len;
152
153 if (fscache_set_key(cookie, index_key, index_key_len) < 0)
154 goto nomem;
155
156 if (cookie->aux_len <= sizeof(cookie->inline_aux)) {
157 memcpy(cookie->inline_aux, aux_data, cookie->aux_len);
158 } else {
159 cookie->aux = kmemdup(aux_data, cookie->aux_len, GFP_KERNEL);
160 if (!cookie->aux)
161 goto nomem;
162 }
163
164 atomic_set(&cookie->usage, 1);
165 atomic_set(&cookie->n_children, 0);
166
167 /* We keep the active count elevated until relinquishment to prevent an
168 * attempt to wake up every time the object operations queue quiesces.
169 */
170 atomic_set(&cookie->n_active, 1);
171
172 cookie->def = def;
173 cookie->parent = parent;
174 cookie->netfs_data = netfs_data;
175 cookie->flags = (1 << FSCACHE_COOKIE_NO_DATA_YET);
176 cookie->type = def->type;
177 spin_lock_init(&cookie->lock);
178 spin_lock_init(&cookie->stores_lock);
179 INIT_HLIST_HEAD(&cookie->backing_objects);
180
181 /* radix tree insertion won't use the preallocation pool unless it's
182 * told it may not wait */
183 INIT_RADIX_TREE(&cookie->stores, GFP_NOFS & ~__GFP_DIRECT_RECLAIM);
184 return cookie;
185
186 nomem:
187 fscache_free_cookie(cookie);
188 return NULL;
189 }
190
191 /*
192 * Attempt to insert the new cookie into the hash. If there's a collision, we
193 * return the old cookie if it's not in use and an error otherwise.
194 */
fscache_hash_cookie(struct fscache_cookie * candidate)195 struct fscache_cookie *fscache_hash_cookie(struct fscache_cookie *candidate)
196 {
197 struct fscache_cookie *cursor;
198 struct hlist_bl_head *h;
199 struct hlist_bl_node *p;
200 unsigned int bucket;
201
202 bucket = candidate->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
203 h = &fscache_cookie_hash[bucket];
204
205 hlist_bl_lock(h);
206 hlist_bl_for_each_entry(cursor, p, h, hash_link) {
207 if (fscache_compare_cookie(candidate, cursor) == 0)
208 goto collision;
209 }
210
211 __set_bit(FSCACHE_COOKIE_ACQUIRED, &candidate->flags);
212 fscache_cookie_get(candidate->parent, fscache_cookie_get_acquire_parent);
213 atomic_inc(&candidate->parent->n_children);
214 hlist_bl_add_head(&candidate->hash_link, h);
215 hlist_bl_unlock(h);
216 return candidate;
217
218 collision:
219 if (test_and_set_bit(FSCACHE_COOKIE_ACQUIRED, &cursor->flags)) {
220 trace_fscache_cookie(cursor, fscache_cookie_collision,
221 atomic_read(&cursor->usage));
222 pr_err("Duplicate cookie detected\n");
223 fscache_print_cookie(cursor, 'O');
224 fscache_print_cookie(candidate, 'N');
225 hlist_bl_unlock(h);
226 return NULL;
227 }
228
229 fscache_cookie_get(cursor, fscache_cookie_get_reacquire);
230 hlist_bl_unlock(h);
231 return cursor;
232 }
233
234 /*
235 * request a cookie to represent an object (index, datafile, xattr, etc)
236 * - parent specifies the parent object
237 * - the top level index cookie for each netfs is stored in the fscache_netfs
238 * struct upon registration
239 * - def points to the definition
240 * - the netfs_data will be passed to the functions pointed to in *def
241 * - all attached caches will be searched to see if they contain this object
242 * - index objects aren't stored on disk until there's a dependent file that
243 * needs storing
244 * - other objects are stored in a selected cache immediately, and all the
245 * indices forming the path to it are instantiated if necessary
246 * - we never let on to the netfs about errors
247 * - we may set a negative cookie pointer, but that's okay
248 */
__fscache_acquire_cookie(struct fscache_cookie * parent,const struct fscache_cookie_def * def,const void * index_key,size_t index_key_len,const void * aux_data,size_t aux_data_len,void * netfs_data,loff_t object_size,bool enable)249 struct fscache_cookie *__fscache_acquire_cookie(
250 struct fscache_cookie *parent,
251 const struct fscache_cookie_def *def,
252 const void *index_key, size_t index_key_len,
253 const void *aux_data, size_t aux_data_len,
254 void *netfs_data,
255 loff_t object_size,
256 bool enable)
257 {
258 struct fscache_cookie *candidate, *cookie;
259
260 BUG_ON(!def);
261
262 _enter("{%s},{%s},%p,%u",
263 parent ? (char *) parent->def->name : "<no-parent>",
264 def->name, netfs_data, enable);
265
266 if (!index_key || !index_key_len || index_key_len > 255 || aux_data_len > 255)
267 return NULL;
268 if (!aux_data || !aux_data_len) {
269 aux_data = NULL;
270 aux_data_len = 0;
271 }
272
273 fscache_stat(&fscache_n_acquires);
274
275 /* if there's no parent cookie, then we don't create one here either */
276 if (!parent) {
277 fscache_stat(&fscache_n_acquires_null);
278 _leave(" [no parent]");
279 return NULL;
280 }
281
282 /* validate the definition */
283 BUG_ON(!def->name[0]);
284
285 BUG_ON(def->type == FSCACHE_COOKIE_TYPE_INDEX &&
286 parent->type != FSCACHE_COOKIE_TYPE_INDEX);
287
288 candidate = fscache_alloc_cookie(parent, def,
289 index_key, index_key_len,
290 aux_data, aux_data_len,
291 netfs_data, object_size);
292 if (!candidate) {
293 fscache_stat(&fscache_n_acquires_oom);
294 _leave(" [ENOMEM]");
295 return NULL;
296 }
297
298 cookie = fscache_hash_cookie(candidate);
299 if (!cookie) {
300 trace_fscache_cookie(candidate, fscache_cookie_discard, 1);
301 goto out;
302 }
303
304 if (cookie == candidate)
305 candidate = NULL;
306
307 switch (cookie->type) {
308 case FSCACHE_COOKIE_TYPE_INDEX:
309 fscache_stat(&fscache_n_cookie_index);
310 break;
311 case FSCACHE_COOKIE_TYPE_DATAFILE:
312 fscache_stat(&fscache_n_cookie_data);
313 break;
314 default:
315 fscache_stat(&fscache_n_cookie_special);
316 break;
317 }
318
319 trace_fscache_acquire(cookie);
320
321 if (enable) {
322 /* if the object is an index then we need do nothing more here
323 * - we create indices on disk when we need them as an index
324 * may exist in multiple caches */
325 if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX) {
326 if (fscache_acquire_non_index_cookie(cookie, object_size) == 0) {
327 set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
328 } else {
329 atomic_dec(&parent->n_children);
330 fscache_cookie_put(cookie,
331 fscache_cookie_put_acquire_nobufs);
332 fscache_stat(&fscache_n_acquires_nobufs);
333 _leave(" = NULL");
334 return NULL;
335 }
336 } else {
337 set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
338 }
339 }
340
341 fscache_stat(&fscache_n_acquires_ok);
342
343 out:
344 fscache_free_cookie(candidate);
345 return cookie;
346 }
347 EXPORT_SYMBOL(__fscache_acquire_cookie);
348
349 /*
350 * Enable a cookie to permit it to accept new operations.
351 */
__fscache_enable_cookie(struct fscache_cookie * cookie,const void * aux_data,loff_t object_size,bool (* can_enable)(void * data),void * data)352 void __fscache_enable_cookie(struct fscache_cookie *cookie,
353 const void *aux_data,
354 loff_t object_size,
355 bool (*can_enable)(void *data),
356 void *data)
357 {
358 _enter("%p", cookie);
359
360 trace_fscache_enable(cookie);
361
362 wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
363 TASK_UNINTERRUPTIBLE);
364
365 fscache_update_aux(cookie, aux_data);
366
367 if (test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
368 goto out_unlock;
369
370 if (can_enable && !can_enable(data)) {
371 /* The netfs decided it didn't want to enable after all */
372 } else if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX) {
373 /* Wait for outstanding disablement to complete */
374 __fscache_wait_on_invalidate(cookie);
375
376 if (fscache_acquire_non_index_cookie(cookie, object_size) == 0)
377 set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
378 } else {
379 set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
380 }
381
382 out_unlock:
383 clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
384 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
385 }
386 EXPORT_SYMBOL(__fscache_enable_cookie);
387
388 /*
389 * acquire a non-index cookie
390 * - this must make sure the index chain is instantiated and instantiate the
391 * object representation too
392 */
fscache_acquire_non_index_cookie(struct fscache_cookie * cookie,loff_t object_size)393 static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie,
394 loff_t object_size)
395 {
396 struct fscache_object *object;
397 struct fscache_cache *cache;
398 int ret;
399
400 _enter("");
401
402 set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
403
404 /* now we need to see whether the backing objects for this cookie yet
405 * exist, if not there'll be nothing to search */
406 down_read(&fscache_addremove_sem);
407
408 if (list_empty(&fscache_cache_list)) {
409 up_read(&fscache_addremove_sem);
410 _leave(" = 0 [no caches]");
411 return 0;
412 }
413
414 /* select a cache in which to store the object */
415 cache = fscache_select_cache_for_object(cookie->parent);
416 if (!cache) {
417 up_read(&fscache_addremove_sem);
418 fscache_stat(&fscache_n_acquires_no_cache);
419 _leave(" = -ENOMEDIUM [no cache]");
420 return -ENOMEDIUM;
421 }
422
423 _debug("cache %s", cache->tag->name);
424
425 set_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
426
427 /* ask the cache to allocate objects for this cookie and its parent
428 * chain */
429 ret = fscache_alloc_object(cache, cookie);
430 if (ret < 0) {
431 up_read(&fscache_addremove_sem);
432 _leave(" = %d", ret);
433 return ret;
434 }
435
436 spin_lock(&cookie->lock);
437 if (hlist_empty(&cookie->backing_objects)) {
438 spin_unlock(&cookie->lock);
439 goto unavailable;
440 }
441
442 object = hlist_entry(cookie->backing_objects.first,
443 struct fscache_object, cookie_link);
444
445 fscache_set_store_limit(object, object_size);
446
447 /* initiate the process of looking up all the objects in the chain
448 * (done by fscache_initialise_object()) */
449 fscache_raise_event(object, FSCACHE_OBJECT_EV_NEW_CHILD);
450
451 spin_unlock(&cookie->lock);
452
453 /* we may be required to wait for lookup to complete at this point */
454 if (!fscache_defer_lookup) {
455 _debug("non-deferred lookup %p", &cookie->flags);
456 wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
457 TASK_UNINTERRUPTIBLE);
458 _debug("complete");
459 if (test_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags))
460 goto unavailable;
461 }
462
463 up_read(&fscache_addremove_sem);
464 _leave(" = 0 [deferred]");
465 return 0;
466
467 unavailable:
468 up_read(&fscache_addremove_sem);
469 _leave(" = -ENOBUFS");
470 return -ENOBUFS;
471 }
472
473 /*
474 * recursively allocate cache object records for a cookie/cache combination
475 * - caller must be holding the addremove sem
476 */
fscache_alloc_object(struct fscache_cache * cache,struct fscache_cookie * cookie)477 static int fscache_alloc_object(struct fscache_cache *cache,
478 struct fscache_cookie *cookie)
479 {
480 struct fscache_object *object;
481 int ret;
482
483 _enter("%p,%p{%s}", cache, cookie, cookie->def->name);
484
485 spin_lock(&cookie->lock);
486 hlist_for_each_entry(object, &cookie->backing_objects,
487 cookie_link) {
488 if (object->cache == cache)
489 goto object_already_extant;
490 }
491 spin_unlock(&cookie->lock);
492
493 /* ask the cache to allocate an object (we may end up with duplicate
494 * objects at this stage, but we sort that out later) */
495 fscache_stat(&fscache_n_cop_alloc_object);
496 object = cache->ops->alloc_object(cache, cookie);
497 fscache_stat_d(&fscache_n_cop_alloc_object);
498 if (IS_ERR(object)) {
499 fscache_stat(&fscache_n_object_no_alloc);
500 ret = PTR_ERR(object);
501 goto error;
502 }
503
504 ASSERTCMP(object->cookie, ==, cookie);
505 fscache_stat(&fscache_n_object_alloc);
506
507 object->debug_id = atomic_inc_return(&fscache_object_debug_id);
508
509 _debug("ALLOC OBJ%x: %s {%lx}",
510 object->debug_id, cookie->def->name, object->events);
511
512 ret = fscache_alloc_object(cache, cookie->parent);
513 if (ret < 0)
514 goto error_put;
515
516 /* only attach if we managed to allocate all we needed, otherwise
517 * discard the object we just allocated and instead use the one
518 * attached to the cookie */
519 if (fscache_attach_object(cookie, object) < 0) {
520 fscache_stat(&fscache_n_cop_put_object);
521 cache->ops->put_object(object, fscache_obj_put_attach_fail);
522 fscache_stat_d(&fscache_n_cop_put_object);
523 }
524
525 _leave(" = 0");
526 return 0;
527
528 object_already_extant:
529 ret = -ENOBUFS;
530 if (fscache_object_is_dying(object) ||
531 fscache_cache_is_broken(object)) {
532 spin_unlock(&cookie->lock);
533 goto error;
534 }
535 spin_unlock(&cookie->lock);
536 _leave(" = 0 [found]");
537 return 0;
538
539 error_put:
540 fscache_stat(&fscache_n_cop_put_object);
541 cache->ops->put_object(object, fscache_obj_put_alloc_fail);
542 fscache_stat_d(&fscache_n_cop_put_object);
543 error:
544 _leave(" = %d", ret);
545 return ret;
546 }
547
548 /*
549 * attach a cache object to a cookie
550 */
fscache_attach_object(struct fscache_cookie * cookie,struct fscache_object * object)551 static int fscache_attach_object(struct fscache_cookie *cookie,
552 struct fscache_object *object)
553 {
554 struct fscache_object *p;
555 struct fscache_cache *cache = object->cache;
556 int ret;
557
558 _enter("{%s},{OBJ%x}", cookie->def->name, object->debug_id);
559
560 ASSERTCMP(object->cookie, ==, cookie);
561
562 spin_lock(&cookie->lock);
563
564 /* there may be multiple initial creations of this object, but we only
565 * want one */
566 ret = -EEXIST;
567 hlist_for_each_entry(p, &cookie->backing_objects, cookie_link) {
568 if (p->cache == object->cache) {
569 if (fscache_object_is_dying(p))
570 ret = -ENOBUFS;
571 goto cant_attach_object;
572 }
573 }
574
575 /* pin the parent object */
576 spin_lock_nested(&cookie->parent->lock, 1);
577 hlist_for_each_entry(p, &cookie->parent->backing_objects,
578 cookie_link) {
579 if (p->cache == object->cache) {
580 if (fscache_object_is_dying(p)) {
581 ret = -ENOBUFS;
582 spin_unlock(&cookie->parent->lock);
583 goto cant_attach_object;
584 }
585 object->parent = p;
586 spin_lock(&p->lock);
587 p->n_children++;
588 spin_unlock(&p->lock);
589 break;
590 }
591 }
592 spin_unlock(&cookie->parent->lock);
593
594 /* attach to the cache's object list */
595 if (list_empty(&object->cache_link)) {
596 spin_lock(&cache->object_list_lock);
597 list_add(&object->cache_link, &cache->object_list);
598 spin_unlock(&cache->object_list_lock);
599 }
600
601 /* Attach to the cookie. The object already has a ref on it. */
602 hlist_add_head(&object->cookie_link, &cookie->backing_objects);
603
604 fscache_objlist_add(object);
605 ret = 0;
606
607 cant_attach_object:
608 spin_unlock(&cookie->lock);
609 _leave(" = %d", ret);
610 return ret;
611 }
612
613 /*
614 * Invalidate an object. Callable with spinlocks held.
615 */
__fscache_invalidate(struct fscache_cookie * cookie)616 void __fscache_invalidate(struct fscache_cookie *cookie)
617 {
618 struct fscache_object *object;
619
620 _enter("{%s}", cookie->def->name);
621
622 fscache_stat(&fscache_n_invalidates);
623
624 /* Only permit invalidation of data files. Invalidating an index will
625 * require the caller to release all its attachments to the tree rooted
626 * there, and if it's doing that, it may as well just retire the
627 * cookie.
628 */
629 ASSERTCMP(cookie->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
630
631 /* If there's an object, we tell the object state machine to handle the
632 * invalidation on our behalf, otherwise there's nothing to do.
633 */
634 if (!hlist_empty(&cookie->backing_objects)) {
635 spin_lock(&cookie->lock);
636
637 if (fscache_cookie_enabled(cookie) &&
638 !hlist_empty(&cookie->backing_objects) &&
639 !test_and_set_bit(FSCACHE_COOKIE_INVALIDATING,
640 &cookie->flags)) {
641 object = hlist_entry(cookie->backing_objects.first,
642 struct fscache_object,
643 cookie_link);
644 if (fscache_object_is_live(object))
645 fscache_raise_event(
646 object, FSCACHE_OBJECT_EV_INVALIDATE);
647 }
648
649 spin_unlock(&cookie->lock);
650 }
651
652 _leave("");
653 }
654 EXPORT_SYMBOL(__fscache_invalidate);
655
656 /*
657 * Wait for object invalidation to complete.
658 */
__fscache_wait_on_invalidate(struct fscache_cookie * cookie)659 void __fscache_wait_on_invalidate(struct fscache_cookie *cookie)
660 {
661 _enter("%p", cookie);
662
663 wait_on_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING,
664 TASK_UNINTERRUPTIBLE);
665
666 _leave("");
667 }
668 EXPORT_SYMBOL(__fscache_wait_on_invalidate);
669
670 /*
671 * update the index entries backing a cookie
672 */
__fscache_update_cookie(struct fscache_cookie * cookie,const void * aux_data)673 void __fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data)
674 {
675 struct fscache_object *object;
676
677 fscache_stat(&fscache_n_updates);
678
679 if (!cookie) {
680 fscache_stat(&fscache_n_updates_null);
681 _leave(" [no cookie]");
682 return;
683 }
684
685 _enter("{%s}", cookie->def->name);
686
687 spin_lock(&cookie->lock);
688
689 fscache_update_aux(cookie, aux_data);
690
691 if (fscache_cookie_enabled(cookie)) {
692 /* update the index entry on disk in each cache backing this
693 * cookie.
694 */
695 hlist_for_each_entry(object,
696 &cookie->backing_objects, cookie_link) {
697 fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
698 }
699 }
700
701 spin_unlock(&cookie->lock);
702 _leave("");
703 }
704 EXPORT_SYMBOL(__fscache_update_cookie);
705
706 /*
707 * Disable a cookie to stop it from accepting new requests from the netfs.
708 */
__fscache_disable_cookie(struct fscache_cookie * cookie,const void * aux_data,bool invalidate)709 void __fscache_disable_cookie(struct fscache_cookie *cookie,
710 const void *aux_data,
711 bool invalidate)
712 {
713 struct fscache_object *object;
714 bool awaken = false;
715
716 _enter("%p,%u", cookie, invalidate);
717
718 trace_fscache_disable(cookie);
719
720 ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
721
722 if (atomic_read(&cookie->n_children) != 0) {
723 pr_err("Cookie '%s' still has children\n",
724 cookie->def->name);
725 BUG();
726 }
727
728 wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
729 TASK_UNINTERRUPTIBLE);
730
731 fscache_update_aux(cookie, aux_data);
732
733 if (!test_and_clear_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
734 goto out_unlock_enable;
735
736 /* If the cookie is being invalidated, wait for that to complete first
737 * so that we can reuse the flag.
738 */
739 __fscache_wait_on_invalidate(cookie);
740
741 /* Dispose of the backing objects */
742 set_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags);
743
744 spin_lock(&cookie->lock);
745 if (!hlist_empty(&cookie->backing_objects)) {
746 hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
747 if (invalidate)
748 set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
749 clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
750 fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
751 }
752 } else {
753 if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
754 awaken = true;
755 }
756 spin_unlock(&cookie->lock);
757 if (awaken)
758 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);
759
760 /* Wait for cessation of activity requiring access to the netfs (when
761 * n_active reaches 0). This makes sure outstanding reads and writes
762 * have completed.
763 */
764 if (!atomic_dec_and_test(&cookie->n_active)) {
765 wait_var_event(&cookie->n_active,
766 !atomic_read(&cookie->n_active));
767 }
768
769 /* Make sure any pending writes are cancelled. */
770 if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX)
771 fscache_invalidate_writes(cookie);
772
773 /* Reset the cookie state if it wasn't relinquished */
774 if (!test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags)) {
775 atomic_inc(&cookie->n_active);
776 set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
777 }
778
779 out_unlock_enable:
780 clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
781 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
782 _leave("");
783 }
784 EXPORT_SYMBOL(__fscache_disable_cookie);
785
786 /*
787 * release a cookie back to the cache
788 * - the object will be marked as recyclable on disk if retire is true
789 * - all dependents of this cookie must have already been unregistered
790 * (indices/files/pages)
791 */
__fscache_relinquish_cookie(struct fscache_cookie * cookie,const void * aux_data,bool retire)792 void __fscache_relinquish_cookie(struct fscache_cookie *cookie,
793 const void *aux_data,
794 bool retire)
795 {
796 fscache_stat(&fscache_n_relinquishes);
797 if (retire)
798 fscache_stat(&fscache_n_relinquishes_retire);
799
800 if (!cookie) {
801 fscache_stat(&fscache_n_relinquishes_null);
802 _leave(" [no cookie]");
803 return;
804 }
805
806 _enter("%p{%s,%p,%d},%d",
807 cookie, cookie->def->name, cookie->netfs_data,
808 atomic_read(&cookie->n_active), retire);
809
810 trace_fscache_relinquish(cookie, retire);
811
812 /* No further netfs-accessing operations on this cookie permitted */
813 if (test_and_set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags))
814 BUG();
815
816 __fscache_disable_cookie(cookie, aux_data, retire);
817
818 /* Clear pointers back to the netfs */
819 cookie->netfs_data = NULL;
820 cookie->def = NULL;
821 BUG_ON(!radix_tree_empty(&cookie->stores));
822
823 if (cookie->parent) {
824 ASSERTCMP(atomic_read(&cookie->parent->usage), >, 0);
825 ASSERTCMP(atomic_read(&cookie->parent->n_children), >, 0);
826 atomic_dec(&cookie->parent->n_children);
827 }
828
829 /* Dispose of the netfs's link to the cookie */
830 ASSERTCMP(atomic_read(&cookie->usage), >, 0);
831 fscache_cookie_put(cookie, fscache_cookie_put_relinquish);
832
833 _leave("");
834 }
835 EXPORT_SYMBOL(__fscache_relinquish_cookie);
836
837 /*
838 * Remove a cookie from the hash table.
839 */
fscache_unhash_cookie(struct fscache_cookie * cookie)840 static void fscache_unhash_cookie(struct fscache_cookie *cookie)
841 {
842 struct hlist_bl_head *h;
843 unsigned int bucket;
844
845 bucket = cookie->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
846 h = &fscache_cookie_hash[bucket];
847
848 hlist_bl_lock(h);
849 hlist_bl_del(&cookie->hash_link);
850 hlist_bl_unlock(h);
851 }
852
853 /*
854 * Drop a reference to a cookie.
855 */
fscache_cookie_put(struct fscache_cookie * cookie,enum fscache_cookie_trace where)856 void fscache_cookie_put(struct fscache_cookie *cookie,
857 enum fscache_cookie_trace where)
858 {
859 struct fscache_cookie *parent;
860 int usage;
861
862 _enter("%p", cookie);
863
864 do {
865 usage = atomic_dec_return(&cookie->usage);
866 trace_fscache_cookie(cookie, where, usage);
867
868 if (usage > 0)
869 return;
870 BUG_ON(usage < 0);
871
872 parent = cookie->parent;
873 fscache_unhash_cookie(cookie);
874 fscache_free_cookie(cookie);
875
876 cookie = parent;
877 where = fscache_cookie_put_parent;
878 } while (cookie);
879
880 _leave("");
881 }
882
883 /*
884 * check the consistency between the netfs inode and the backing cache
885 *
886 * NOTE: it only serves no-index type
887 */
__fscache_check_consistency(struct fscache_cookie * cookie,const void * aux_data)888 int __fscache_check_consistency(struct fscache_cookie *cookie,
889 const void *aux_data)
890 {
891 struct fscache_operation *op;
892 struct fscache_object *object;
893 bool wake_cookie = false;
894 int ret;
895
896 _enter("%p,", cookie);
897
898 ASSERTCMP(cookie->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
899
900 if (fscache_wait_for_deferred_lookup(cookie) < 0)
901 return -ERESTARTSYS;
902
903 if (hlist_empty(&cookie->backing_objects))
904 return 0;
905
906 op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
907 if (!op)
908 return -ENOMEM;
909
910 fscache_operation_init(cookie, op, NULL, NULL, NULL);
911 op->flags = FSCACHE_OP_MYTHREAD |
912 (1 << FSCACHE_OP_WAITING) |
913 (1 << FSCACHE_OP_UNUSE_COOKIE);
914 trace_fscache_page_op(cookie, NULL, op, fscache_page_op_check_consistency);
915
916 spin_lock(&cookie->lock);
917
918 fscache_update_aux(cookie, aux_data);
919
920 if (!fscache_cookie_enabled(cookie) ||
921 hlist_empty(&cookie->backing_objects))
922 goto inconsistent;
923 object = hlist_entry(cookie->backing_objects.first,
924 struct fscache_object, cookie_link);
925 if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
926 goto inconsistent;
927
928 op->debug_id = atomic_inc_return(&fscache_op_debug_id);
929
930 __fscache_use_cookie(cookie);
931 if (fscache_submit_op(object, op) < 0)
932 goto submit_failed;
933
934 /* the work queue now carries its own ref on the object */
935 spin_unlock(&cookie->lock);
936
937 ret = fscache_wait_for_operation_activation(object, op, NULL, NULL);
938 if (ret == 0) {
939 /* ask the cache to honour the operation */
940 ret = object->cache->ops->check_consistency(op);
941 fscache_op_complete(op, false);
942 } else if (ret == -ENOBUFS) {
943 ret = 0;
944 }
945
946 fscache_put_operation(op);
947 _leave(" = %d", ret);
948 return ret;
949
950 submit_failed:
951 wake_cookie = __fscache_unuse_cookie(cookie);
952 inconsistent:
953 spin_unlock(&cookie->lock);
954 if (wake_cookie)
955 __fscache_wake_unused_cookie(cookie);
956 kfree(op);
957 _leave(" = -ESTALE");
958 return -ESTALE;
959 }
960 EXPORT_SYMBOL(__fscache_check_consistency);
961