xref: /linux/fs/netfs/fscache_cookie.c (revision 4ac0f08f44b62e59a389c7ed87c89087d9fefe29)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* netfs cookie management
3  *
4  * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  *
7  * See Documentation/filesystems/caching/netfs-api.rst 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 void fscache_cookie_lru_timed_out(struct timer_list *timer);
19 static void fscache_cookie_lru_worker(struct work_struct *work);
20 static void fscache_cookie_worker(struct work_struct *work);
21 static void fscache_unhash_cookie(struct fscache_cookie *cookie);
22 static void fscache_perform_invalidation(struct fscache_cookie *cookie);
23 
24 #define fscache_cookie_hash_shift 15
25 static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
26 static LIST_HEAD(fscache_cookies);
27 static DEFINE_RWLOCK(fscache_cookies_lock);
28 static LIST_HEAD(fscache_cookie_lru);
29 static DEFINE_SPINLOCK(fscache_cookie_lru_lock);
30 DEFINE_TIMER(fscache_cookie_lru_timer, fscache_cookie_lru_timed_out);
31 static DECLARE_WORK(fscache_cookie_lru_work, fscache_cookie_lru_worker);
32 static const char fscache_cookie_states[FSCACHE_COOKIE_STATE__NR] = "-LCAIFUWRD";
33 static unsigned int fscache_lru_cookie_timeout = 10 * HZ;
34 
fscache_print_cookie(struct fscache_cookie * cookie,char prefix)35 void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
36 {
37 	const u8 *k;
38 
39 	pr_err("%c-cookie c=%08x [fl=%lx na=%u nA=%u s=%c]\n",
40 	       prefix,
41 	       cookie->debug_id,
42 	       cookie->flags,
43 	       atomic_read(&cookie->n_active),
44 	       atomic_read(&cookie->n_accesses),
45 	       fscache_cookie_states[cookie->state]);
46 	pr_err("%c-cookie V=%08x [%s]\n",
47 	       prefix,
48 	       cookie->volume->debug_id,
49 	       cookie->volume->key);
50 
51 	k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
52 		cookie->inline_key : cookie->key;
53 	pr_err("%c-key=[%u] '%*phN'\n", prefix, cookie->key_len, cookie->key_len, k);
54 }
55 
fscache_free_cookie(struct fscache_cookie * cookie)56 static void fscache_free_cookie(struct fscache_cookie *cookie)
57 {
58 	if (WARN_ON_ONCE(!list_empty(&cookie->commit_link))) {
59 		spin_lock(&fscache_cookie_lru_lock);
60 		list_del_init(&cookie->commit_link);
61 		spin_unlock(&fscache_cookie_lru_lock);
62 		fscache_stat_d(&fscache_n_cookies_lru);
63 		fscache_stat(&fscache_n_cookies_lru_removed);
64 	}
65 
66 	if (WARN_ON_ONCE(test_bit(FSCACHE_COOKIE_IS_HASHED, &cookie->flags))) {
67 		fscache_print_cookie(cookie, 'F');
68 		return;
69 	}
70 
71 	write_lock(&fscache_cookies_lock);
72 	list_del(&cookie->proc_link);
73 	write_unlock(&fscache_cookies_lock);
74 	if (cookie->aux_len > sizeof(cookie->inline_aux))
75 		kfree(cookie->aux);
76 	if (cookie->key_len > sizeof(cookie->inline_key))
77 		kfree(cookie->key);
78 	fscache_stat_d(&fscache_n_cookies);
79 	kmem_cache_free(fscache_cookie_jar, cookie);
80 }
81 
__fscache_queue_cookie(struct fscache_cookie * cookie)82 static void __fscache_queue_cookie(struct fscache_cookie *cookie)
83 {
84 	if (!queue_work(fscache_wq, &cookie->work))
85 		fscache_put_cookie(cookie, fscache_cookie_put_over_queued);
86 }
87 
fscache_queue_cookie(struct fscache_cookie * cookie,enum fscache_cookie_trace where)88 static void fscache_queue_cookie(struct fscache_cookie *cookie,
89 				 enum fscache_cookie_trace where)
90 {
91 	fscache_get_cookie(cookie, where);
92 	__fscache_queue_cookie(cookie);
93 }
94 
95 /*
96  * Initialise the access gate on a cookie by setting a flag to prevent the
97  * state machine from being queued when the access counter transitions to 0.
98  * We're only interested in this when we withdraw caching services from the
99  * cookie.
100  */
fscache_init_access_gate(struct fscache_cookie * cookie)101 static void fscache_init_access_gate(struct fscache_cookie *cookie)
102 {
103 	int n_accesses;
104 
105 	n_accesses = atomic_read(&cookie->n_accesses);
106 	trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
107 			     n_accesses, fscache_access_cache_pin);
108 	set_bit(FSCACHE_COOKIE_NO_ACCESS_WAKE, &cookie->flags);
109 }
110 
111 /**
112  * fscache_end_cookie_access - Unpin a cache at the end of an access.
113  * @cookie: A data file cookie
114  * @why: An indication of the circumstances of the access for tracing
115  *
116  * Unpin a cache cookie after we've accessed it and bring a deferred
117  * relinquishment or withdrawal state into effect.
118  *
119  * The @why indicator is provided for tracing purposes.
120  */
fscache_end_cookie_access(struct fscache_cookie * cookie,enum fscache_access_trace why)121 void fscache_end_cookie_access(struct fscache_cookie *cookie,
122 			       enum fscache_access_trace why)
123 {
124 	int n_accesses;
125 
126 	smp_mb__before_atomic();
127 	n_accesses = atomic_dec_return(&cookie->n_accesses);
128 	trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
129 			     n_accesses, why);
130 	if (n_accesses == 0 &&
131 	    !test_bit(FSCACHE_COOKIE_NO_ACCESS_WAKE, &cookie->flags))
132 		fscache_queue_cookie(cookie, fscache_cookie_get_end_access);
133 }
134 EXPORT_SYMBOL(fscache_end_cookie_access);
135 
136 /*
137  * Pin the cache behind a cookie so that we can access it.
138  */
__fscache_begin_cookie_access(struct fscache_cookie * cookie,enum fscache_access_trace why)139 static void __fscache_begin_cookie_access(struct fscache_cookie *cookie,
140 					  enum fscache_access_trace why)
141 {
142 	int n_accesses;
143 
144 	n_accesses = atomic_inc_return(&cookie->n_accesses);
145 	smp_mb__after_atomic(); /* (Future) read state after is-caching.
146 				 * Reread n_accesses after is-caching
147 				 */
148 	trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
149 			     n_accesses, why);
150 }
151 
152 /**
153  * fscache_begin_cookie_access - Pin a cache so data can be accessed
154  * @cookie: A data file cookie
155  * @why: An indication of the circumstances of the access for tracing
156  *
157  * Attempt to pin the cache to prevent it from going away whilst we're
158  * accessing data and returns true if successful.  This works as follows:
159  *
160  *  (1) If the cookie is not being cached (ie. FSCACHE_COOKIE_IS_CACHING is not
161  *      set), we return false to indicate access was not permitted.
162  *
163  *  (2) If the cookie is being cached, we increment its n_accesses count and
164  *      then recheck the IS_CACHING flag, ending the access if it got cleared.
165  *
166  *  (3) When we end the access, we decrement the cookie's n_accesses and wake
167  *      up the any waiters if it reaches 0.
168  *
169  *  (4) Whilst the cookie is actively being cached, its n_accesses is kept
170  *      artificially incremented to prevent wakeups from happening.
171  *
172  *  (5) When the cache is taken offline or if the cookie is culled, the flag is
173  *      cleared to prevent new accesses, the cookie's n_accesses is decremented
174  *      and we wait for it to become 0.
175  *
176  * The @why indicator are merely provided for tracing purposes.
177  */
fscache_begin_cookie_access(struct fscache_cookie * cookie,enum fscache_access_trace why)178 bool fscache_begin_cookie_access(struct fscache_cookie *cookie,
179 				 enum fscache_access_trace why)
180 {
181 	if (!test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags))
182 		return false;
183 	__fscache_begin_cookie_access(cookie, why);
184 	if (!test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags) ||
185 	    !fscache_cache_is_live(cookie->volume->cache)) {
186 		fscache_end_cookie_access(cookie, fscache_access_unlive);
187 		return false;
188 	}
189 	return true;
190 }
191 
wake_up_cookie_state(struct fscache_cookie * cookie)192 static inline void wake_up_cookie_state(struct fscache_cookie *cookie)
193 {
194 	/* Use a barrier to ensure that waiters see the state variable
195 	 * change, as spin_unlock doesn't guarantee a barrier.
196 	 *
197 	 * See comments over wake_up_bit() and waitqueue_active().
198 	 */
199 	smp_mb();
200 	wake_up_var(&cookie->state);
201 }
202 
203 /*
204  * Change the state a cookie is at and wake up anyone waiting for that.  Impose
205  * an ordering between the stuff stored in the cookie and the state member.
206  * Paired with fscache_cookie_state().
207  */
__fscache_set_cookie_state(struct fscache_cookie * cookie,enum fscache_cookie_state state)208 static void __fscache_set_cookie_state(struct fscache_cookie *cookie,
209 				       enum fscache_cookie_state state)
210 {
211 	smp_store_release(&cookie->state, state);
212 }
213 
fscache_set_cookie_state(struct fscache_cookie * cookie,enum fscache_cookie_state state)214 static void fscache_set_cookie_state(struct fscache_cookie *cookie,
215 				     enum fscache_cookie_state state)
216 {
217 	spin_lock(&cookie->lock);
218 	__fscache_set_cookie_state(cookie, state);
219 	spin_unlock(&cookie->lock);
220 	wake_up_cookie_state(cookie);
221 }
222 
223 /**
224  * fscache_cookie_lookup_negative - Note negative lookup
225  * @cookie: The cookie that was being looked up
226  *
227  * Note that some part of the metadata path in the cache doesn't exist and so
228  * we can release any waiting readers in the certain knowledge that there's
229  * nothing for them to actually read.
230  *
231  * This function uses no locking and must only be called from the state machine.
232  */
fscache_cookie_lookup_negative(struct fscache_cookie * cookie)233 void fscache_cookie_lookup_negative(struct fscache_cookie *cookie)
234 {
235 	set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
236 	fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_CREATING);
237 }
238 EXPORT_SYMBOL(fscache_cookie_lookup_negative);
239 
240 /**
241  * fscache_resume_after_invalidation - Allow I/O to resume after invalidation
242  * @cookie: The cookie that was invalidated
243  *
244  * Tell fscache that invalidation is sufficiently complete that I/O can be
245  * allowed again.
246  */
fscache_resume_after_invalidation(struct fscache_cookie * cookie)247 void fscache_resume_after_invalidation(struct fscache_cookie *cookie)
248 {
249 	fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_ACTIVE);
250 }
251 EXPORT_SYMBOL(fscache_resume_after_invalidation);
252 
253 /**
254  * fscache_caching_failed - Report that a failure stopped caching on a cookie
255  * @cookie: The cookie that was affected
256  *
257  * Tell fscache that caching on a cookie needs to be stopped due to some sort
258  * of failure.
259  *
260  * This function uses no locking and must only be called from the state machine.
261  */
fscache_caching_failed(struct fscache_cookie * cookie)262 void fscache_caching_failed(struct fscache_cookie *cookie)
263 {
264 	clear_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags);
265 	fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_FAILED);
266 	trace_fscache_cookie(cookie->debug_id, refcount_read(&cookie->ref),
267 				fscache_cookie_failed);
268 }
269 EXPORT_SYMBOL(fscache_caching_failed);
270 
271 /*
272  * Set the index key in a cookie.  The cookie struct has space for a 16-byte
273  * key plus length and hash, but if that's not big enough, it's instead a
274  * pointer to a buffer containing 3 bytes of hash, 1 byte of length and then
275  * the key data.
276  */
fscache_set_key(struct fscache_cookie * cookie,const void * index_key,size_t index_key_len)277 static int fscache_set_key(struct fscache_cookie *cookie,
278 			   const void *index_key, size_t index_key_len)
279 {
280 	void *buf;
281 	size_t buf_size;
282 
283 	buf_size = round_up(index_key_len, sizeof(__le32));
284 
285 	if (index_key_len > sizeof(cookie->inline_key)) {
286 		buf = kzalloc(buf_size, GFP_KERNEL);
287 		if (!buf)
288 			return -ENOMEM;
289 		cookie->key = buf;
290 	} else {
291 		buf = cookie->inline_key;
292 	}
293 
294 	memcpy(buf, index_key, index_key_len);
295 	cookie->key_hash = fscache_hash(cookie->volume->key_hash,
296 					buf, buf_size);
297 	return 0;
298 }
299 
fscache_cookie_same(const struct fscache_cookie * a,const struct fscache_cookie * b)300 static bool fscache_cookie_same(const struct fscache_cookie *a,
301 				const struct fscache_cookie *b)
302 {
303 	const void *ka, *kb;
304 
305 	if (a->key_hash	!= b->key_hash ||
306 	    a->volume	!= b->volume ||
307 	    a->key_len	!= b->key_len)
308 		return false;
309 
310 	if (a->key_len <= sizeof(a->inline_key)) {
311 		ka = &a->inline_key;
312 		kb = &b->inline_key;
313 	} else {
314 		ka = a->key;
315 		kb = b->key;
316 	}
317 	return memcmp(ka, kb, a->key_len) == 0;
318 }
319 
320 static atomic_t fscache_cookie_debug_id = ATOMIC_INIT(1);
321 
322 /*
323  * Allocate a cookie.
324  */
fscache_alloc_cookie(struct fscache_volume * volume,u8 advice,const void * index_key,size_t index_key_len,const void * aux_data,size_t aux_data_len,loff_t object_size)325 static struct fscache_cookie *fscache_alloc_cookie(
326 	struct fscache_volume *volume,
327 	u8 advice,
328 	const void *index_key, size_t index_key_len,
329 	const void *aux_data, size_t aux_data_len,
330 	loff_t object_size)
331 {
332 	struct fscache_cookie *cookie;
333 
334 	/* allocate and initialise a cookie */
335 	cookie = kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
336 	if (!cookie)
337 		return NULL;
338 	fscache_stat(&fscache_n_cookies);
339 
340 	cookie->volume		= volume;
341 	cookie->advice		= advice;
342 	cookie->key_len		= index_key_len;
343 	cookie->aux_len		= aux_data_len;
344 	cookie->object_size	= object_size;
345 	if (object_size == 0)
346 		__set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
347 
348 	if (fscache_set_key(cookie, index_key, index_key_len) < 0)
349 		goto nomem;
350 
351 	if (cookie->aux_len <= sizeof(cookie->inline_aux)) {
352 		memcpy(cookie->inline_aux, aux_data, cookie->aux_len);
353 	} else {
354 		cookie->aux = kmemdup(aux_data, cookie->aux_len, GFP_KERNEL);
355 		if (!cookie->aux)
356 			goto nomem;
357 	}
358 
359 	refcount_set(&cookie->ref, 1);
360 	cookie->debug_id = atomic_inc_return(&fscache_cookie_debug_id);
361 	spin_lock_init(&cookie->lock);
362 	INIT_LIST_HEAD(&cookie->commit_link);
363 	INIT_WORK(&cookie->work, fscache_cookie_worker);
364 	__fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_QUIESCENT);
365 
366 	write_lock(&fscache_cookies_lock);
367 	list_add_tail(&cookie->proc_link, &fscache_cookies);
368 	write_unlock(&fscache_cookies_lock);
369 	fscache_see_cookie(cookie, fscache_cookie_new_acquire);
370 	return cookie;
371 
372 nomem:
373 	fscache_free_cookie(cookie);
374 	return NULL;
375 }
376 
fscache_cookie_is_dropped(struct fscache_cookie * cookie)377 static inline bool fscache_cookie_is_dropped(struct fscache_cookie *cookie)
378 {
379 	return READ_ONCE(cookie->state) == FSCACHE_COOKIE_STATE_DROPPED;
380 }
381 
fscache_wait_on_collision(struct fscache_cookie * candidate,struct fscache_cookie * wait_for)382 static void fscache_wait_on_collision(struct fscache_cookie *candidate,
383 				      struct fscache_cookie *wait_for)
384 {
385 	enum fscache_cookie_state *statep = &wait_for->state;
386 
387 	wait_var_event_timeout(statep, fscache_cookie_is_dropped(wait_for),
388 			       20 * HZ);
389 	if (!fscache_cookie_is_dropped(wait_for)) {
390 		pr_notice("Potential collision c=%08x old: c=%08x",
391 			  candidate->debug_id, wait_for->debug_id);
392 		wait_var_event(statep, fscache_cookie_is_dropped(wait_for));
393 	}
394 }
395 
396 /*
397  * Attempt to insert the new cookie into the hash.  If there's a collision, we
398  * wait for the old cookie to complete if it's being relinquished and an error
399  * otherwise.
400  */
fscache_hash_cookie(struct fscache_cookie * candidate)401 static bool fscache_hash_cookie(struct fscache_cookie *candidate)
402 {
403 	struct fscache_cookie *cursor, *wait_for = NULL;
404 	struct hlist_bl_head *h;
405 	struct hlist_bl_node *p;
406 	unsigned int bucket;
407 
408 	bucket = candidate->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
409 	h = &fscache_cookie_hash[bucket];
410 
411 	hlist_bl_lock(h);
412 	hlist_bl_for_each_entry(cursor, p, h, hash_link) {
413 		if (fscache_cookie_same(candidate, cursor)) {
414 			if (!test_bit(FSCACHE_COOKIE_RELINQUISHED, &cursor->flags))
415 				goto collision;
416 			wait_for = fscache_get_cookie(cursor,
417 						      fscache_cookie_get_hash_collision);
418 			break;
419 		}
420 	}
421 
422 	fscache_get_volume(candidate->volume, fscache_volume_get_cookie);
423 	atomic_inc(&candidate->volume->n_cookies);
424 	hlist_bl_add_head(&candidate->hash_link, h);
425 	set_bit(FSCACHE_COOKIE_IS_HASHED, &candidate->flags);
426 	hlist_bl_unlock(h);
427 
428 	if (wait_for) {
429 		fscache_wait_on_collision(candidate, wait_for);
430 		fscache_put_cookie(wait_for, fscache_cookie_put_hash_collision);
431 	}
432 	return true;
433 
434 collision:
435 	trace_fscache_cookie(cursor->debug_id, refcount_read(&cursor->ref),
436 			     fscache_cookie_collision);
437 	pr_err("Duplicate cookie detected\n");
438 	fscache_print_cookie(cursor, 'O');
439 	fscache_print_cookie(candidate, 'N');
440 	hlist_bl_unlock(h);
441 	return false;
442 }
443 
444 /*
445  * Request a cookie to represent a data storage object within a volume.
446  *
447  * We never let on to the netfs about errors.  We may set a negative cookie
448  * pointer, but that's okay
449  */
__fscache_acquire_cookie(struct fscache_volume * volume,u8 advice,const void * index_key,size_t index_key_len,const void * aux_data,size_t aux_data_len,loff_t object_size)450 struct fscache_cookie *__fscache_acquire_cookie(
451 	struct fscache_volume *volume,
452 	u8 advice,
453 	const void *index_key, size_t index_key_len,
454 	const void *aux_data, size_t aux_data_len,
455 	loff_t object_size)
456 {
457 	struct fscache_cookie *cookie;
458 
459 	_enter("V=%x", volume->debug_id);
460 
461 	if (!index_key || !index_key_len || index_key_len > 255 || aux_data_len > 255)
462 		return NULL;
463 	if (!aux_data || !aux_data_len) {
464 		aux_data = NULL;
465 		aux_data_len = 0;
466 	}
467 
468 	fscache_stat(&fscache_n_acquires);
469 
470 	cookie = fscache_alloc_cookie(volume, advice,
471 				      index_key, index_key_len,
472 				      aux_data, aux_data_len,
473 				      object_size);
474 	if (!cookie) {
475 		fscache_stat(&fscache_n_acquires_oom);
476 		return NULL;
477 	}
478 
479 	if (!fscache_hash_cookie(cookie)) {
480 		fscache_see_cookie(cookie, fscache_cookie_discard);
481 		fscache_free_cookie(cookie);
482 		return NULL;
483 	}
484 
485 	trace_fscache_acquire(cookie);
486 	fscache_stat(&fscache_n_acquires_ok);
487 	_leave(" = c=%08x", cookie->debug_id);
488 	return cookie;
489 }
490 EXPORT_SYMBOL(__fscache_acquire_cookie);
491 
492 /*
493  * Prepare a cache object to be written to.
494  */
fscache_prepare_to_write(struct fscache_cookie * cookie)495 static void fscache_prepare_to_write(struct fscache_cookie *cookie)
496 {
497 	cookie->volume->cache->ops->prepare_to_write(cookie);
498 }
499 
500 /*
501  * Look up a cookie in the cache.
502  */
fscache_perform_lookup(struct fscache_cookie * cookie)503 static void fscache_perform_lookup(struct fscache_cookie *cookie)
504 {
505 	enum fscache_access_trace trace = fscache_access_lookup_cookie_end_failed;
506 	bool need_withdraw = false;
507 
508 	_enter("");
509 
510 	if (!cookie->volume->cache_priv) {
511 		fscache_create_volume(cookie->volume, true);
512 		if (!cookie->volume->cache_priv) {
513 			fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_QUIESCENT);
514 			goto out;
515 		}
516 	}
517 
518 	if (!cookie->volume->cache->ops->lookup_cookie(cookie)) {
519 		if (cookie->state != FSCACHE_COOKIE_STATE_FAILED)
520 			fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_QUIESCENT);
521 		need_withdraw = true;
522 		_leave(" [fail]");
523 		goto out;
524 	}
525 
526 	fscache_see_cookie(cookie, fscache_cookie_see_active);
527 	spin_lock(&cookie->lock);
528 	if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
529 		__fscache_set_cookie_state(cookie,
530 					   FSCACHE_COOKIE_STATE_INVALIDATING);
531 	else
532 		__fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_ACTIVE);
533 	spin_unlock(&cookie->lock);
534 	wake_up_cookie_state(cookie);
535 	trace = fscache_access_lookup_cookie_end;
536 
537 out:
538 	fscache_end_cookie_access(cookie, trace);
539 	if (need_withdraw)
540 		fscache_withdraw_cookie(cookie);
541 	fscache_end_volume_access(cookie->volume, cookie, trace);
542 }
543 
544 /*
545  * Begin the process of looking up a cookie.  We offload the actual process to
546  * a worker thread.
547  */
fscache_begin_lookup(struct fscache_cookie * cookie,bool will_modify)548 static bool fscache_begin_lookup(struct fscache_cookie *cookie, bool will_modify)
549 {
550 	if (will_modify) {
551 		set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags);
552 		set_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
553 	}
554 	if (!fscache_begin_volume_access(cookie->volume, cookie,
555 					 fscache_access_lookup_cookie))
556 		return false;
557 
558 	__fscache_begin_cookie_access(cookie, fscache_access_lookup_cookie);
559 	__fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_LOOKING_UP);
560 	set_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags);
561 	set_bit(FSCACHE_COOKIE_HAS_BEEN_CACHED, &cookie->flags);
562 	return true;
563 }
564 
565 /*
566  * Start using the cookie for I/O.  This prevents the backing object from being
567  * reaped by VM pressure.
568  */
__fscache_use_cookie(struct fscache_cookie * cookie,bool will_modify)569 void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify)
570 {
571 	enum fscache_cookie_state state;
572 	bool queue = false;
573 	int n_active;
574 
575 	_enter("c=%08x", cookie->debug_id);
576 
577 	if (WARN(test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
578 		 "Trying to use relinquished cookie\n"))
579 		return;
580 
581 	spin_lock(&cookie->lock);
582 
583 	n_active = atomic_inc_return(&cookie->n_active);
584 	trace_fscache_active(cookie->debug_id, refcount_read(&cookie->ref),
585 			     n_active, atomic_read(&cookie->n_accesses),
586 			     will_modify ?
587 			     fscache_active_use_modify : fscache_active_use);
588 
589 again:
590 	state = fscache_cookie_state(cookie);
591 	switch (state) {
592 	case FSCACHE_COOKIE_STATE_QUIESCENT:
593 		queue = fscache_begin_lookup(cookie, will_modify);
594 		break;
595 
596 	case FSCACHE_COOKIE_STATE_LOOKING_UP:
597 	case FSCACHE_COOKIE_STATE_CREATING:
598 		if (will_modify)
599 			set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags);
600 		break;
601 	case FSCACHE_COOKIE_STATE_ACTIVE:
602 	case FSCACHE_COOKIE_STATE_INVALIDATING:
603 		if (will_modify &&
604 		    !test_and_set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags)) {
605 			set_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
606 			queue = true;
607 		}
608 		/*
609 		 * We could race with cookie_lru which may set LRU_DISCARD bit
610 		 * but has yet to run the cookie state machine.  If this happens
611 		 * and another thread tries to use the cookie, clear LRU_DISCARD
612 		 * so we don't end up withdrawing the cookie while in use.
613 		 */
614 		if (test_and_clear_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags))
615 			fscache_see_cookie(cookie, fscache_cookie_see_lru_discard_clear);
616 		break;
617 
618 	case FSCACHE_COOKIE_STATE_FAILED:
619 	case FSCACHE_COOKIE_STATE_WITHDRAWING:
620 		break;
621 
622 	case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
623 		spin_unlock(&cookie->lock);
624 		wait_var_event(&cookie->state,
625 			       fscache_cookie_state(cookie) !=
626 			       FSCACHE_COOKIE_STATE_LRU_DISCARDING);
627 		spin_lock(&cookie->lock);
628 		goto again;
629 
630 	case FSCACHE_COOKIE_STATE_DROPPED:
631 	case FSCACHE_COOKIE_STATE_RELINQUISHING:
632 		WARN(1, "Can't use cookie in state %u\n", state);
633 		break;
634 	}
635 
636 	spin_unlock(&cookie->lock);
637 	if (queue)
638 		fscache_queue_cookie(cookie, fscache_cookie_get_use_work);
639 	_leave("");
640 }
641 EXPORT_SYMBOL(__fscache_use_cookie);
642 
fscache_unuse_cookie_locked(struct fscache_cookie * cookie)643 static void fscache_unuse_cookie_locked(struct fscache_cookie *cookie)
644 {
645 	clear_bit(FSCACHE_COOKIE_DISABLED, &cookie->flags);
646 	if (!test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags))
647 		return;
648 
649 	cookie->unused_at = jiffies;
650 	spin_lock(&fscache_cookie_lru_lock);
651 	if (list_empty(&cookie->commit_link)) {
652 		fscache_get_cookie(cookie, fscache_cookie_get_lru);
653 		fscache_stat(&fscache_n_cookies_lru);
654 	}
655 	list_move_tail(&cookie->commit_link, &fscache_cookie_lru);
656 
657 	spin_unlock(&fscache_cookie_lru_lock);
658 	timer_reduce(&fscache_cookie_lru_timer,
659 		     jiffies + fscache_lru_cookie_timeout);
660 }
661 
662 /*
663  * Stop using the cookie for I/O.
664  */
__fscache_unuse_cookie(struct fscache_cookie * cookie,const void * aux_data,const loff_t * object_size)665 void __fscache_unuse_cookie(struct fscache_cookie *cookie,
666 			    const void *aux_data, const loff_t *object_size)
667 {
668 	unsigned int debug_id = cookie->debug_id;
669 	unsigned int r = refcount_read(&cookie->ref);
670 	unsigned int a = atomic_read(&cookie->n_accesses);
671 	unsigned int c;
672 
673 	if (aux_data || object_size)
674 		__fscache_update_cookie(cookie, aux_data, object_size);
675 
676 	/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
677 	c = atomic_fetch_add_unless(&cookie->n_active, -1, 1);
678 	if (c != 1) {
679 		trace_fscache_active(debug_id, r, c - 1, a, fscache_active_unuse);
680 		return;
681 	}
682 
683 	spin_lock(&cookie->lock);
684 	r = refcount_read(&cookie->ref);
685 	a = atomic_read(&cookie->n_accesses);
686 	c = atomic_dec_return(&cookie->n_active);
687 	trace_fscache_active(debug_id, r, c, a, fscache_active_unuse);
688 	if (c == 0)
689 		fscache_unuse_cookie_locked(cookie);
690 	spin_unlock(&cookie->lock);
691 }
692 EXPORT_SYMBOL(__fscache_unuse_cookie);
693 
694 /*
695  * Perform work upon the cookie, such as committing its cache state,
696  * relinquishing it or withdrawing the backing cache.  We're protected from the
697  * cache going away under us as object withdrawal must come through this
698  * non-reentrant work item.
699  */
fscache_cookie_state_machine(struct fscache_cookie * cookie)700 static void fscache_cookie_state_machine(struct fscache_cookie *cookie)
701 {
702 	enum fscache_cookie_state state;
703 	bool wake = false;
704 
705 	_enter("c=%x", cookie->debug_id);
706 
707 again:
708 	spin_lock(&cookie->lock);
709 again_locked:
710 	state = cookie->state;
711 	switch (state) {
712 	case FSCACHE_COOKIE_STATE_QUIESCENT:
713 		/* The QUIESCENT state is jumped to the LOOKING_UP state by
714 		 * fscache_use_cookie().
715 		 */
716 
717 		if (atomic_read(&cookie->n_accesses) == 0 &&
718 		    test_bit(FSCACHE_COOKIE_DO_RELINQUISH, &cookie->flags)) {
719 			__fscache_set_cookie_state(cookie,
720 						   FSCACHE_COOKIE_STATE_RELINQUISHING);
721 			wake = true;
722 			goto again_locked;
723 		}
724 		break;
725 
726 	case FSCACHE_COOKIE_STATE_LOOKING_UP:
727 		spin_unlock(&cookie->lock);
728 		fscache_init_access_gate(cookie);
729 		fscache_perform_lookup(cookie);
730 		goto again;
731 
732 	case FSCACHE_COOKIE_STATE_INVALIDATING:
733 		spin_unlock(&cookie->lock);
734 		fscache_perform_invalidation(cookie);
735 		goto again;
736 
737 	case FSCACHE_COOKIE_STATE_ACTIVE:
738 		if (test_and_clear_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags)) {
739 			spin_unlock(&cookie->lock);
740 			fscache_prepare_to_write(cookie);
741 			spin_lock(&cookie->lock);
742 		}
743 		if (test_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags)) {
744 			if (atomic_read(&cookie->n_accesses) != 0)
745 				/* still being accessed: postpone it */
746 				break;
747 
748 			__fscache_set_cookie_state(cookie,
749 						   FSCACHE_COOKIE_STATE_LRU_DISCARDING);
750 			wake = true;
751 			goto again_locked;
752 		}
753 		fallthrough;
754 
755 	case FSCACHE_COOKIE_STATE_FAILED:
756 		if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
757 			fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
758 
759 		if (atomic_read(&cookie->n_accesses) != 0)
760 			break;
761 		if (test_bit(FSCACHE_COOKIE_DO_RELINQUISH, &cookie->flags)) {
762 			__fscache_set_cookie_state(cookie,
763 						   FSCACHE_COOKIE_STATE_RELINQUISHING);
764 			wake = true;
765 			goto again_locked;
766 		}
767 		if (test_bit(FSCACHE_COOKIE_DO_WITHDRAW, &cookie->flags)) {
768 			__fscache_set_cookie_state(cookie,
769 						   FSCACHE_COOKIE_STATE_WITHDRAWING);
770 			wake = true;
771 			goto again_locked;
772 		}
773 		break;
774 
775 	case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
776 	case FSCACHE_COOKIE_STATE_RELINQUISHING:
777 	case FSCACHE_COOKIE_STATE_WITHDRAWING:
778 		if (cookie->cache_priv) {
779 			spin_unlock(&cookie->lock);
780 			cookie->volume->cache->ops->withdraw_cookie(cookie);
781 			spin_lock(&cookie->lock);
782 		}
783 
784 		if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
785 			fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
786 
787 		switch (state) {
788 		case FSCACHE_COOKIE_STATE_RELINQUISHING:
789 			fscache_see_cookie(cookie, fscache_cookie_see_relinquish);
790 			fscache_unhash_cookie(cookie);
791 			__fscache_set_cookie_state(cookie,
792 						   FSCACHE_COOKIE_STATE_DROPPED);
793 			wake = true;
794 			goto out;
795 		case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
796 			fscache_see_cookie(cookie, fscache_cookie_see_lru_discard);
797 			break;
798 		case FSCACHE_COOKIE_STATE_WITHDRAWING:
799 			fscache_see_cookie(cookie, fscache_cookie_see_withdraw);
800 			break;
801 		default:
802 			BUG();
803 		}
804 
805 		clear_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
806 		clear_bit(FSCACHE_COOKIE_DO_WITHDRAW, &cookie->flags);
807 		clear_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags);
808 		clear_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
809 		set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
810 		__fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_QUIESCENT);
811 		wake = true;
812 		goto again_locked;
813 
814 	case FSCACHE_COOKIE_STATE_DROPPED:
815 		break;
816 
817 	default:
818 		WARN_ONCE(1, "Cookie %x in unexpected state %u\n",
819 			  cookie->debug_id, state);
820 		break;
821 	}
822 
823 out:
824 	spin_unlock(&cookie->lock);
825 	if (wake)
826 		wake_up_cookie_state(cookie);
827 	_leave("");
828 }
829 
fscache_cookie_worker(struct work_struct * work)830 static void fscache_cookie_worker(struct work_struct *work)
831 {
832 	struct fscache_cookie *cookie = container_of(work, struct fscache_cookie, work);
833 
834 	fscache_see_cookie(cookie, fscache_cookie_see_work);
835 	fscache_cookie_state_machine(cookie);
836 	fscache_put_cookie(cookie, fscache_cookie_put_work);
837 }
838 
839 /*
840  * Wait for the object to become inactive.  The cookie's work item will be
841  * scheduled when someone transitions n_accesses to 0 - but if someone's
842  * already done that, schedule it anyway.
843  */
__fscache_withdraw_cookie(struct fscache_cookie * cookie)844 static void __fscache_withdraw_cookie(struct fscache_cookie *cookie)
845 {
846 	int n_accesses;
847 	bool unpinned;
848 
849 	unpinned = test_and_clear_bit(FSCACHE_COOKIE_NO_ACCESS_WAKE, &cookie->flags);
850 
851 	/* Need to read the access count after unpinning */
852 	n_accesses = atomic_read(&cookie->n_accesses);
853 	if (unpinned)
854 		trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
855 				     n_accesses, fscache_access_cache_unpin);
856 	if (n_accesses == 0)
857 		fscache_queue_cookie(cookie, fscache_cookie_get_end_access);
858 }
859 
fscache_cookie_lru_do_one(struct fscache_cookie * cookie)860 static void fscache_cookie_lru_do_one(struct fscache_cookie *cookie)
861 {
862 	fscache_see_cookie(cookie, fscache_cookie_see_lru_do_one);
863 
864 	spin_lock(&cookie->lock);
865 	if (cookie->state != FSCACHE_COOKIE_STATE_ACTIVE ||
866 	    time_before(jiffies, cookie->unused_at + fscache_lru_cookie_timeout) ||
867 	    atomic_read(&cookie->n_active) > 0) {
868 		spin_unlock(&cookie->lock);
869 		fscache_stat(&fscache_n_cookies_lru_removed);
870 	} else {
871 		set_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags);
872 		spin_unlock(&cookie->lock);
873 		fscache_stat(&fscache_n_cookies_lru_expired);
874 		_debug("lru c=%x", cookie->debug_id);
875 		__fscache_withdraw_cookie(cookie);
876 	}
877 
878 	fscache_put_cookie(cookie, fscache_cookie_put_lru);
879 }
880 
fscache_cookie_lru_worker(struct work_struct * work)881 static void fscache_cookie_lru_worker(struct work_struct *work)
882 {
883 	struct fscache_cookie *cookie;
884 	unsigned long unused_at;
885 
886 	spin_lock(&fscache_cookie_lru_lock);
887 
888 	while (!list_empty(&fscache_cookie_lru)) {
889 		cookie = list_first_entry(&fscache_cookie_lru,
890 					  struct fscache_cookie, commit_link);
891 		unused_at = cookie->unused_at + fscache_lru_cookie_timeout;
892 		if (time_before(jiffies, unused_at)) {
893 			timer_reduce(&fscache_cookie_lru_timer, unused_at);
894 			break;
895 		}
896 
897 		list_del_init(&cookie->commit_link);
898 		fscache_stat_d(&fscache_n_cookies_lru);
899 		spin_unlock(&fscache_cookie_lru_lock);
900 		fscache_cookie_lru_do_one(cookie);
901 		spin_lock(&fscache_cookie_lru_lock);
902 	}
903 
904 	spin_unlock(&fscache_cookie_lru_lock);
905 }
906 
fscache_cookie_lru_timed_out(struct timer_list * timer)907 static void fscache_cookie_lru_timed_out(struct timer_list *timer)
908 {
909 	queue_work(fscache_wq, &fscache_cookie_lru_work);
910 }
911 
fscache_cookie_drop_from_lru(struct fscache_cookie * cookie)912 static void fscache_cookie_drop_from_lru(struct fscache_cookie *cookie)
913 {
914 	bool need_put = false;
915 
916 	if (!list_empty(&cookie->commit_link)) {
917 		spin_lock(&fscache_cookie_lru_lock);
918 		if (!list_empty(&cookie->commit_link)) {
919 			list_del_init(&cookie->commit_link);
920 			fscache_stat_d(&fscache_n_cookies_lru);
921 			fscache_stat(&fscache_n_cookies_lru_dropped);
922 			need_put = true;
923 		}
924 		spin_unlock(&fscache_cookie_lru_lock);
925 		if (need_put)
926 			fscache_put_cookie(cookie, fscache_cookie_put_lru);
927 	}
928 }
929 
930 /*
931  * Remove a cookie from the hash table.
932  */
fscache_unhash_cookie(struct fscache_cookie * cookie)933 static void fscache_unhash_cookie(struct fscache_cookie *cookie)
934 {
935 	struct hlist_bl_head *h;
936 	unsigned int bucket;
937 
938 	bucket = cookie->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
939 	h = &fscache_cookie_hash[bucket];
940 
941 	hlist_bl_lock(h);
942 	hlist_bl_del(&cookie->hash_link);
943 	clear_bit(FSCACHE_COOKIE_IS_HASHED, &cookie->flags);
944 	hlist_bl_unlock(h);
945 	fscache_stat(&fscache_n_relinquishes_dropped);
946 }
947 
fscache_drop_withdraw_cookie(struct fscache_cookie * cookie)948 static void fscache_drop_withdraw_cookie(struct fscache_cookie *cookie)
949 {
950 	fscache_cookie_drop_from_lru(cookie);
951 	__fscache_withdraw_cookie(cookie);
952 }
953 
954 /**
955  * fscache_withdraw_cookie - Mark a cookie for withdrawal
956  * @cookie: The cookie to be withdrawn.
957  *
958  * Allow the cache backend to withdraw the backing for a cookie for its own
959  * reasons, even if that cookie is in active use.
960  */
fscache_withdraw_cookie(struct fscache_cookie * cookie)961 void fscache_withdraw_cookie(struct fscache_cookie *cookie)
962 {
963 	set_bit(FSCACHE_COOKIE_DO_WITHDRAW, &cookie->flags);
964 	fscache_drop_withdraw_cookie(cookie);
965 }
966 EXPORT_SYMBOL(fscache_withdraw_cookie);
967 
968 /*
969  * Allow the netfs to release a cookie back to the cache.
970  * - the object will be marked as recyclable on disk if retire is true
971  */
__fscache_relinquish_cookie(struct fscache_cookie * cookie,bool retire)972 void __fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
973 {
974 	fscache_stat(&fscache_n_relinquishes);
975 	if (retire)
976 		fscache_stat(&fscache_n_relinquishes_retire);
977 
978 	_enter("c=%08x{%d},%d",
979 	       cookie->debug_id, atomic_read(&cookie->n_active), retire);
980 
981 	if (WARN(test_and_set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
982 		 "Cookie c=%x already relinquished\n", cookie->debug_id))
983 		return;
984 
985 	if (retire)
986 		set_bit(FSCACHE_COOKIE_RETIRED, &cookie->flags);
987 	trace_fscache_relinquish(cookie, retire);
988 
989 	ASSERTCMP(atomic_read(&cookie->n_active), ==, 0);
990 	ASSERTCMP(atomic_read(&cookie->volume->n_cookies), >, 0);
991 	atomic_dec(&cookie->volume->n_cookies);
992 
993 	if (test_bit(FSCACHE_COOKIE_HAS_BEEN_CACHED, &cookie->flags)) {
994 		set_bit(FSCACHE_COOKIE_DO_RELINQUISH, &cookie->flags);
995 		fscache_drop_withdraw_cookie(cookie);
996 	} else {
997 		fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_DROPPED);
998 		fscache_unhash_cookie(cookie);
999 	}
1000 	fscache_put_cookie(cookie, fscache_cookie_put_relinquish);
1001 }
1002 EXPORT_SYMBOL(__fscache_relinquish_cookie);
1003 
1004 /*
1005  * Drop a reference to a cookie.
1006  */
fscache_put_cookie(struct fscache_cookie * cookie,enum fscache_cookie_trace where)1007 void fscache_put_cookie(struct fscache_cookie *cookie,
1008 			enum fscache_cookie_trace where)
1009 {
1010 	struct fscache_volume *volume = cookie->volume;
1011 	unsigned int cookie_debug_id = cookie->debug_id;
1012 	bool zero;
1013 	int ref;
1014 
1015 	zero = __refcount_dec_and_test(&cookie->ref, &ref);
1016 	trace_fscache_cookie(cookie_debug_id, ref - 1, where);
1017 	if (zero) {
1018 		fscache_free_cookie(cookie);
1019 		fscache_put_volume(volume, fscache_volume_put_cookie);
1020 	}
1021 }
1022 EXPORT_SYMBOL(fscache_put_cookie);
1023 
1024 /*
1025  * Get a reference to a cookie.
1026  */
fscache_get_cookie(struct fscache_cookie * cookie,enum fscache_cookie_trace where)1027 struct fscache_cookie *fscache_get_cookie(struct fscache_cookie *cookie,
1028 					  enum fscache_cookie_trace where)
1029 {
1030 	int ref;
1031 
1032 	__refcount_inc(&cookie->ref, &ref);
1033 	trace_fscache_cookie(cookie->debug_id, ref + 1, where);
1034 	return cookie;
1035 }
1036 EXPORT_SYMBOL(fscache_get_cookie);
1037 
1038 /*
1039  * Ask the cache to effect invalidation of a cookie.
1040  */
fscache_perform_invalidation(struct fscache_cookie * cookie)1041 static void fscache_perform_invalidation(struct fscache_cookie *cookie)
1042 {
1043 	if (!cookie->volume->cache->ops->invalidate_cookie(cookie))
1044 		fscache_caching_failed(cookie);
1045 	fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
1046 }
1047 
1048 /*
1049  * Invalidate an object.
1050  */
__fscache_invalidate(struct fscache_cookie * cookie,const void * aux_data,loff_t new_size,unsigned int flags)1051 void __fscache_invalidate(struct fscache_cookie *cookie,
1052 			  const void *aux_data, loff_t new_size,
1053 			  unsigned int flags)
1054 {
1055 	bool is_caching;
1056 
1057 	_enter("c=%x", cookie->debug_id);
1058 
1059 	fscache_stat(&fscache_n_invalidates);
1060 
1061 	if (WARN(test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
1062 		 "Trying to invalidate relinquished cookie\n"))
1063 		return;
1064 
1065 	if ((flags & FSCACHE_INVAL_DIO_WRITE) &&
1066 	    test_and_set_bit(FSCACHE_COOKIE_DISABLED, &cookie->flags))
1067 		return;
1068 
1069 	spin_lock(&cookie->lock);
1070 	set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
1071 	fscache_update_aux(cookie, aux_data, &new_size);
1072 	cookie->inval_counter++;
1073 	trace_fscache_invalidate(cookie, new_size);
1074 
1075 	switch (cookie->state) {
1076 	case FSCACHE_COOKIE_STATE_INVALIDATING: /* is_still_valid will catch it */
1077 	default:
1078 		spin_unlock(&cookie->lock);
1079 		_leave(" [no %u]", cookie->state);
1080 		return;
1081 
1082 	case FSCACHE_COOKIE_STATE_LOOKING_UP:
1083 		if (!test_and_set_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
1084 			__fscache_begin_cookie_access(cookie, fscache_access_invalidate_cookie);
1085 		fallthrough;
1086 	case FSCACHE_COOKIE_STATE_CREATING:
1087 		spin_unlock(&cookie->lock);
1088 		_leave(" [look %x]", cookie->inval_counter);
1089 		return;
1090 
1091 	case FSCACHE_COOKIE_STATE_ACTIVE:
1092 		is_caching = fscache_begin_cookie_access(
1093 			cookie, fscache_access_invalidate_cookie);
1094 		if (is_caching)
1095 			__fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_INVALIDATING);
1096 		spin_unlock(&cookie->lock);
1097 		wake_up_cookie_state(cookie);
1098 
1099 		if (is_caching)
1100 			fscache_queue_cookie(cookie, fscache_cookie_get_inval_work);
1101 		_leave(" [inv]");
1102 		return;
1103 	}
1104 }
1105 EXPORT_SYMBOL(__fscache_invalidate);
1106 
1107 #ifdef CONFIG_PROC_FS
1108 /*
1109  * Generate a list of extant cookies in /proc/fs/fscache/cookies
1110  */
fscache_cookies_seq_show(struct seq_file * m,void * v)1111 static int fscache_cookies_seq_show(struct seq_file *m, void *v)
1112 {
1113 	struct fscache_cookie *cookie;
1114 	unsigned int keylen = 0, auxlen = 0;
1115 	u8 *p;
1116 
1117 	if (v == &fscache_cookies) {
1118 		seq_puts(m,
1119 			 "COOKIE   VOLUME   REF ACT ACC S FL DEF             \n"
1120 			 "======== ======== === === === = == ================\n"
1121 			 );
1122 		return 0;
1123 	}
1124 
1125 	cookie = list_entry(v, struct fscache_cookie, proc_link);
1126 
1127 	seq_printf(m,
1128 		   "%08x %08x %3d %3d %3d %c %02lx",
1129 		   cookie->debug_id,
1130 		   cookie->volume->debug_id,
1131 		   refcount_read(&cookie->ref),
1132 		   atomic_read(&cookie->n_active),
1133 		   atomic_read(&cookie->n_accesses),
1134 		   fscache_cookie_states[cookie->state],
1135 		   cookie->flags);
1136 
1137 	keylen = cookie->key_len;
1138 	auxlen = cookie->aux_len;
1139 
1140 	if (keylen > 0 || auxlen > 0) {
1141 		seq_puts(m, " ");
1142 		p = keylen <= sizeof(cookie->inline_key) ?
1143 			cookie->inline_key : cookie->key;
1144 		for (; keylen > 0; keylen--)
1145 			seq_printf(m, "%02x", *p++);
1146 		if (auxlen > 0) {
1147 			seq_puts(m, ", ");
1148 			p = auxlen <= sizeof(cookie->inline_aux) ?
1149 				cookie->inline_aux : cookie->aux;
1150 			for (; auxlen > 0; auxlen--)
1151 				seq_printf(m, "%02x", *p++);
1152 		}
1153 	}
1154 
1155 	seq_puts(m, "\n");
1156 	return 0;
1157 }
1158 
fscache_cookies_seq_start(struct seq_file * m,loff_t * _pos)1159 static void *fscache_cookies_seq_start(struct seq_file *m, loff_t *_pos)
1160 	__acquires(fscache_cookies_lock)
1161 {
1162 	read_lock(&fscache_cookies_lock);
1163 	return seq_list_start_head(&fscache_cookies, *_pos);
1164 }
1165 
fscache_cookies_seq_next(struct seq_file * m,void * v,loff_t * _pos)1166 static void *fscache_cookies_seq_next(struct seq_file *m, void *v, loff_t *_pos)
1167 {
1168 	return seq_list_next(v, &fscache_cookies, _pos);
1169 }
1170 
fscache_cookies_seq_stop(struct seq_file * m,void * v)1171 static void fscache_cookies_seq_stop(struct seq_file *m, void *v)
1172 	__releases(rcu)
1173 {
1174 	read_unlock(&fscache_cookies_lock);
1175 }
1176 
1177 
1178 const struct seq_operations fscache_cookies_seq_ops = {
1179 	.start  = fscache_cookies_seq_start,
1180 	.next   = fscache_cookies_seq_next,
1181 	.stop   = fscache_cookies_seq_stop,
1182 	.show   = fscache_cookies_seq_show,
1183 };
1184 #endif
1185