1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* FS-Cache cache handling
22  * Allocate a cache cookie.
31 			cache->name = kstrdup(name, GFP_KERNEL);  in fscache_alloc_cache()
32 			if (!cache->name) {  in fscache_alloc_cache()
37 		refcount_set(&cache->ref, 1);  in fscache_alloc_cache()
38 		INIT_LIST_HEAD(&cache->cache_link);  in fscache_alloc_cache()
39 		cache->debug_id = atomic_inc_return(&fscache_cache_debug_id);  in fscache_alloc_cache()
50 	success = __refcount_inc_not_zero(&cache->ref, &ref);  in fscache_get_cache_maybe()
52 		trace_fscache_cache(cache->debug_id, ref + 1, where);  in fscache_get_cache_maybe()
57  * Look up a cache cookie.
67 		if (cache->name && name && strcmp(cache->name, name) == 0 &&  in fscache_lookup_cache()
70 		if (!cache->name && !name &&  in fscache_lookup_cache()
77 			if (cache->name &&  in fscache_lookup_cache()
85 	/* the cache does not exist - create a candidate */  in fscache_lookup_cache()
88 		return ERR_PTR(-ENOMEM);  in fscache_lookup_cache()
94 		if (cache->name && name && strcmp(cache->name, name) == 0 &&  in fscache_lookup_cache()
97 		if (!cache->name) {  in fscache_lookup_cache()
111 			if (cache->name &&  in fscache_lookup_cache()
117 	list_add_tail(&candidate->cache_link, &fscache_caches);  in fscache_lookup_cache()
118 	trace_fscache_cache(candidate->debug_id,  in fscache_lookup_cache()
119 			    refcount_read(&candidate->ref),  in fscache_lookup_cache()
129 	cache->name = candidate->name;  in fscache_lookup_cache()
130 	candidate->name = NULL;  in fscache_lookup_cache()
133 	kfree(candidate->name);  in fscache_lookup_cache()
139  * fscache_acquire_cache - Acquire a cache-level cookie.
142  * Get a cookie to represent an actual cache.  If a name is given and there is
143  * a nameless cache record available, this will acquire that and set its name,
147  * use, otherwise -EBUSY will be returned.
163 		return ERR_PTR(-EBUSY);  in fscache_acquire_cache()
171  * fscache_put_cache - Release a cache-level cookie.
175  * Release the caller's reference on a cache-level cookie.  The @where
177  * occurs and will be logged through a tracepoint.
189 	debug_id = cache->debug_id;  in fscache_put_cache()
190 	zero = __refcount_dec_and_test(&cache->ref, &ref);  in fscache_put_cache()
191 	trace_fscache_cache(debug_id, ref - 1, where);  in fscache_put_cache()
195 		list_del_init(&cache->cache_link);  in fscache_put_cache()
197 		kfree(cache->name);  in fscache_put_cache()
203  * fscache_relinquish_cache - Reset cache state and release cookie
206  * Reset the state of a cache and release the caller's reference on a cache
212 		(cache->state == FSCACHE_CACHE_IS_PREPARING) ?  in fscache_relinquish_cache()
216 	cache->ops = NULL;  in fscache_relinquish_cache()
217 	cache->cache_priv = NULL;  in fscache_relinquish_cache()
224  * fscache_add_cache - Declare a cache as being open for business
225  * @cache: The cache-level cookie representing the cache
229  * Add a cache to the system, making it available for netfs's to use.
231  * See Documentation/filesystems/caching/backend-api.rst for a complete
240 	_enter("{%s,%s}", ops->name, cache->name);  in fscache_add_cache()
244 	/* Get a ref on the cache cookie and keep its n_accesses counter raised  in fscache_add_cache()
248 	n_accesses = atomic_inc_return(&cache->n_accesses);  in fscache_add_cache()
249 	trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),  in fscache_add_cache()
254 	cache->ops = ops;  in fscache_add_cache()
255 	cache->cache_priv = cache_priv;  in fscache_add_cache()
259 	pr_notice("Cache \"%s\" added (type %s)\n", cache->name, ops->name);  in fscache_add_cache()
260 	_leave(" = 0 [%s]", cache->name);  in fscache_add_cache()
266  * fscache_begin_cache_access - Pin a cache so it can be accessed
267  * @cache: The cache-level cookie
273  *  (1) If the cache tests as not live (state is not FSCACHE_CACHE_IS_ACTIVE),
276  *  (2) If the cache tests as live, then we increment the n_accesses count and
277  *      then recheck the liveness, ending the access if it ceased to be live.
296 	n_accesses = atomic_inc_return(&cache->n_accesses);  in fscache_begin_cache_access()
297 	smp_mb__after_atomic(); /* Reread live flag after n_accesses */  in fscache_begin_cache_access()
298 	trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),  in fscache_begin_cache_access()
308  * fscache_end_cache_access - Unpin a cache at the end of an access.
309  * @cache: The cache-level cookie
312  * Unpin a cache after we've accessed it.  The @why indicator is merely
320 	n_accesses = atomic_dec_return(&cache->n_accesses);  in fscache_end_cache_access()
321 	trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),  in fscache_end_cache_access()
324 		wake_up_var(&cache->n_accesses);  in fscache_end_cache_access()
328  * fscache_io_error - Note a cache I/O error
331  * Note that an I/O error occurred in a cache and that it should no longer be
334  * See Documentation/filesystems/caching/backend-api.rst for a complete
343 		       cache->name);  in fscache_io_error()
348  * fscache_withdraw_cache - Withdraw a cache from the active service
351  * Begin the process of withdrawing a cache from service.  This stops new
352  * cache-level and volume-level accesses from taking place and waits for
353  * currently ongoing cache-level accesses to end.
360 		  cache->name, atomic_read(&cache->object_count));  in fscache_withdraw_cache()
364 	/* Allow wakeups on dec-to-0 */  in fscache_withdraw_cache()
365 	n_accesses = atomic_dec_return(&cache->n_accesses);  in fscache_withdraw_cache()
366 	trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),  in fscache_withdraw_cache()
369 	wait_var_event(&cache->n_accesses,  in fscache_withdraw_cache()
370 		       atomic_read(&cache->n_accesses) == 0);  in fscache_withdraw_cache()
375 static const char fscache_cache_states[NR__FSCACHE_CACHE_STATE] = "-PAEW";
378  * Generate a list of caches in /proc/fs/fscache/caches
395 		   cache->debug_id,  in fscache_caches_seq_show()
396 		   refcount_read(&cache->ref),  in fscache_caches_seq_show()
397 		   atomic_read(&cache->n_volumes),  in fscache_caches_seq_show()
398 		   atomic_read(&cache->object_count),  in fscache_caches_seq_show()
399 		   atomic_read(&cache->n_accesses),  in fscache_caches_seq_show()
400 		   fscache_cache_states[cache->state],  in fscache_caches_seq_show()
401 		   cache->name ?: "-");  in fscache_caches_seq_show()