2 /* FS-Cache cache handling
8 #define FSCACHE_DEBUG_LEVEL CACHE
22  * Allocate a cache cookie.
26 	struct fscache_cache *cache;  in fscache_alloc_cache()  local
28 	cache = kzalloc(sizeof(*cache), GFP_KERNEL);  in fscache_alloc_cache()
29 	if (cache) {  in fscache_alloc_cache()
31 			cache->name = kstrdup(name, GFP_KERNEL);  in fscache_alloc_cache()
32 			if (!cache->name) {  in fscache_alloc_cache()
33 				kfree(cache);  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()
41 	return cache;  in fscache_alloc_cache()
44 static bool fscache_get_cache_maybe(struct fscache_cache *cache,  in fscache_get_cache_maybe()  argument
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.
61 	struct fscache_cache *candidate, *cache, *unnamed = NULL;  in fscache_lookup_cache()  local
63 	/* firstly check for the existence of the cache under read lock */  in fscache_lookup_cache()
66 	list_for_each_entry(cache, &fscache_caches, cache_link) {  in fscache_lookup_cache()
67 		if (cache->name && name && strcmp(cache->name, name) == 0 &&  in fscache_lookup_cache()
68 		    fscache_get_cache_maybe(cache, fscache_cache_get_acquire))  in fscache_lookup_cache()
70 		if (!cache->name && !name &&  in fscache_lookup_cache()
71 		    fscache_get_cache_maybe(cache, fscache_cache_get_acquire))  in fscache_lookup_cache()
76 		list_for_each_entry(cache, &fscache_caches, cache_link) {  in fscache_lookup_cache()
77 			if (cache->name &&  in fscache_lookup_cache()
78 			    fscache_get_cache_maybe(cache, fscache_cache_get_acquire))  in fscache_lookup_cache()
85 	/* the cache does not exist - create a candidate */  in fscache_lookup_cache()
93 	list_for_each_entry(cache, &fscache_caches, cache_link) {  in fscache_lookup_cache()
94 		if (cache->name && name && strcmp(cache->name, name) == 0 &&  in fscache_lookup_cache()
95 		    fscache_get_cache_maybe(cache, fscache_cache_get_acquire))  in fscache_lookup_cache()
97 		if (!cache->name) {  in fscache_lookup_cache()
98 			unnamed = cache;  in fscache_lookup_cache()
100 			    fscache_get_cache_maybe(cache, fscache_cache_get_acquire))  in fscache_lookup_cache()
110 		list_for_each_entry(cache, &fscache_caches, cache_link) {  in fscache_lookup_cache()
111 			if (cache->name &&  in fscache_lookup_cache()
112 			    fscache_get_cache_maybe(cache, fscache_cache_get_acquire))  in fscache_lookup_cache()
126 	return cache;  in fscache_lookup_cache()
128 	cache = unnamed;  in fscache_lookup_cache()
129 	cache->name = candidate->name;  in fscache_lookup_cache()
135 	return cache;  in fscache_lookup_cache()
139  * fscache_acquire_cache - Acquire a cache-level cookie.
140  * @name: The name of the cache.
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,
144  * directing all the volumes using it to this cache.
146  * The cache will be switched over to the preparing state if not currently in
151 	struct fscache_cache *cache;  in fscache_acquire_cache()  local
154 	cache = fscache_lookup_cache(name, true);  in fscache_acquire_cache()
155 	if (IS_ERR(cache))  in fscache_acquire_cache()
156 		return cache;  in fscache_acquire_cache()
158 	if (!fscache_set_cache_state_maybe(cache,  in fscache_acquire_cache()
161 		pr_warn("Cache tag %s in use\n", name);  in fscache_acquire_cache()
162 		fscache_put_cache(cache, fscache_cache_put_cache);  in fscache_acquire_cache()
166 	return cache;  in fscache_acquire_cache()
171  * fscache_put_cache - Release a cache-level cookie.
172  * @cache: The cache cookie to be released
175  * Release the caller's reference on a cache-level cookie.  The @where
179 void fscache_put_cache(struct fscache_cache *cache,  in fscache_put_cache()  argument
182 	unsigned int debug_id = cache->debug_id;  in fscache_put_cache()
186 	if (IS_ERR_OR_NULL(cache))  in fscache_put_cache()
189 	zero = __refcount_dec_and_test(&cache->ref, &ref);  in fscache_put_cache()
194 		list_del_init(&cache->cache_link);  in fscache_put_cache()
196 		kfree(cache->name);  in fscache_put_cache()
197 		kfree(cache);  in fscache_put_cache()
202  * fscache_relinquish_cache - Reset cache state and release cookie
203  * @cache: The cache cookie to be released
205  * Reset the state of a cache and release the caller's reference on a cache
208 void fscache_relinquish_cache(struct fscache_cache *cache)  in fscache_relinquish_cache()  argument
211 		(cache->state == FSCACHE_CACHE_IS_PREPARING) ?  in fscache_relinquish_cache()
215 	cache->ops = NULL;  in fscache_relinquish_cache()
216 	cache->cache_priv = NULL;  in fscache_relinquish_cache()
217 	fscache_set_cache_state(cache, FSCACHE_CACHE_IS_NOT_PRESENT);  in fscache_relinquish_cache()
218 	fscache_put_cache(cache, where);  in fscache_relinquish_cache()
223  * fscache_add_cache - Declare a cache as being open for business
224  * @cache: The cache-level cookie representing the cache
225  * @ops: Table of cache operations to use
226  * @cache_priv: Private data for the cache record
228  * Add a cache to the system, making it available for netfs's to use.
233 int fscache_add_cache(struct fscache_cache *cache,  in fscache_add_cache()  argument
239 	_enter("{%s,%s}", ops->name, cache->name);  in fscache_add_cache()
241 	BUG_ON(fscache_cache_state(cache) != FSCACHE_CACHE_IS_PREPARING);  in fscache_add_cache()
243 	/* Get a ref on the cache cookie and keep its n_accesses counter raised  in fscache_add_cache()
247 	n_accesses = atomic_inc_return(&cache->n_accesses);  in fscache_add_cache()
248 	trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),  in fscache_add_cache()
253 	cache->ops = ops;  in fscache_add_cache()
254 	cache->cache_priv = cache_priv;  in fscache_add_cache()
255 	fscache_set_cache_state(cache, FSCACHE_CACHE_IS_ACTIVE);  in fscache_add_cache()
258 	pr_notice("Cache \"%s\" added (type %s)\n", cache->name, ops->name);  in fscache_add_cache()
259 	_leave(" = 0 [%s]", cache->name);  in fscache_add_cache()
265  * fscache_begin_cache_access - Pin a cache so it can be accessed
266  * @cache: The cache-level cookie
269  * Attempt to pin the cache to prevent it from going away whilst we're
272  *  (1) If the cache tests as not live (state is not FSCACHE_CACHE_IS_ACTIVE),
275  *  (2) If the cache tests as live, then we increment the n_accesses count and
281  *  (4) Whilst the cache is caching, n_accesses is kept artificially
284  *  (5) When the cache is taken offline, the state is changed to prevent new
288 bool fscache_begin_cache_access(struct fscache_cache *cache, enum fscache_access_trace why)  in fscache_begin_cache_access()  argument
292 	if (!fscache_cache_is_live(cache))  in fscache_begin_cache_access()
295 	n_accesses = atomic_inc_return(&cache->n_accesses);  in fscache_begin_cache_access()
297 	trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),  in fscache_begin_cache_access()
299 	if (!fscache_cache_is_live(cache)) {  in fscache_begin_cache_access()
300 		fscache_end_cache_access(cache, fscache_access_unlive);  in fscache_begin_cache_access()
307  * fscache_end_cache_access - Unpin a cache at the end of an access.
308  * @cache: The cache-level cookie
311  * Unpin a cache after we've accessed it.  The @why indicator is merely
314 void fscache_end_cache_access(struct fscache_cache *cache, enum fscache_access_trace why)  in fscache_end_cache_access()  argument
319 	n_accesses = atomic_dec_return(&cache->n_accesses);  in fscache_end_cache_access()
320 	trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),  in fscache_end_cache_access()
323 		wake_up_var(&cache->n_accesses);  in fscache_end_cache_access()
327  * fscache_io_error - Note a cache I/O error
328  * @cache: The record describing the cache
330  * Note that an I/O error occurred in a cache and that it should no longer be
336 void fscache_io_error(struct fscache_cache *cache)  in fscache_io_error()  argument
338 	if (fscache_set_cache_state_maybe(cache,  in fscache_io_error()
341 		pr_err("Cache '%s' stopped due to I/O error\n",  in fscache_io_error()
342 		       cache->name);  in fscache_io_error()
347  * fscache_withdraw_cache - Withdraw a cache from the active service
348  * @cache: The cache cookie
350  * Begin the process of withdrawing a cache from service.  This stops new
351  * cache-level and volume-level accesses from taking place and waits for
352  * currently ongoing cache-level accesses to end.
354 void fscache_withdraw_cache(struct fscache_cache *cache)  in fscache_withdraw_cache()  argument
358 	pr_notice("Withdrawing cache \"%s\" (%u objs)\n",  in fscache_withdraw_cache()
359 		  cache->name, atomic_read(&cache->object_count));  in fscache_withdraw_cache()
361 	fscache_set_cache_state(cache, FSCACHE_CACHE_IS_WITHDRAWN);  in fscache_withdraw_cache()
364 	n_accesses = atomic_dec_return(&cache->n_accesses);  in fscache_withdraw_cache()
365 	trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),  in fscache_withdraw_cache()
368 	wait_var_event(&cache->n_accesses,  in fscache_withdraw_cache()
369 		       atomic_read(&cache->n_accesses) == 0);  in fscache_withdraw_cache()
381 	struct fscache_cache *cache;  in fscache_caches_seq_show()  local
385 			 "CACHE    REF   VOLS  OBJS  ACCES S NAME\n"  in fscache_caches_seq_show()
391 	cache = list_entry(v, struct fscache_cache, cache_link);  in fscache_caches_seq_show()
394 		   cache->debug_id,  in fscache_caches_seq_show()
395 		   refcount_read(&cache->ref),  in fscache_caches_seq_show()
396 		   atomic_read(&cache->n_volumes),  in fscache_caches_seq_show()
397 		   atomic_read(&cache->object_count),  in fscache_caches_seq_show()
398 		   atomic_read(&cache->n_accesses),  in fscache_caches_seq_show()
399 		   fscache_cache_states[cache->state],  in fscache_caches_seq_show()
400 		   cache->name ?: "-");  in fscache_caches_seq_show()