1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* FS-Cache cache handling
8 #define FSCACHE_DEBUG_LEVEL CACHE
21  * look up a cache tag
31 		if (strcmp(tag->name, name) == 0) {  in __fscache_lookup_cache_tag()
32 			atomic_inc(&tag->usage);  in __fscache_lookup_cache_tag()
40 	/* the tag does not exist - create a candidate */  in __fscache_lookup_cache_tag()
44 		return ERR_PTR(-ENOMEM);  in __fscache_lookup_cache_tag()
46 	atomic_set(&xtag->usage, 1);  in __fscache_lookup_cache_tag()
47 	strcpy(xtag->name, name);  in __fscache_lookup_cache_tag()
53 		if (strcmp(tag->name, name) == 0) {  in __fscache_lookup_cache_tag()
54 			atomic_inc(&tag->usage);  in __fscache_lookup_cache_tag()
61 	list_add_tail(&xtag->link, &fscache_cache_tag_list);  in __fscache_lookup_cache_tag()
67  * release a reference to a cache tag
71 	if (tag != ERR_PTR(-ENOMEM)) {  in __fscache_release_cache_tag()
74 		if (atomic_dec_and_test(&tag->usage))  in __fscache_release_cache_tag()
75 			list_del_init(&tag->link);  in __fscache_release_cache_tag()
86  * select a cache in which to store an object
87  * - the cache addremove semaphore must be at least read-locked by the caller
88  * - the object will never be an index
95 	struct fscache_cache *cache;  in fscache_select_cache_for_object()  local
100 		_leave(" = NULL [no cache]");  in fscache_select_cache_for_object()
104 	/* we check the parent to determine the cache to use */  in fscache_select_cache_for_object()
105 	spin_lock(&cookie->lock);  in fscache_select_cache_for_object()
108 	 * cache */  in fscache_select_cache_for_object()
109 	if (!hlist_empty(&cookie->backing_objects)) {  in fscache_select_cache_for_object()
110 		object = hlist_entry(cookie->backing_objects.first,  in fscache_select_cache_for_object()
113 		cache = object->cache;  in fscache_select_cache_for_object()
115 		    test_bit(FSCACHE_IOERROR, &cache->flags))  in fscache_select_cache_for_object()
116 			cache = NULL;  in fscache_select_cache_for_object()
118 		spin_unlock(&cookie->lock);  in fscache_select_cache_for_object()
119 		_leave(" = %s [parent]", cache ? cache->tag->name : "NULL");  in fscache_select_cache_for_object()
120 		return cache;  in fscache_select_cache_for_object()
124 	if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX) {  in fscache_select_cache_for_object()
126 		spin_unlock(&cookie->lock);  in fscache_select_cache_for_object()
131 	spin_unlock(&cookie->lock);  in fscache_select_cache_for_object()
133 	if (!cookie->def->select_cache)  in fscache_select_cache_for_object()
137 	tag = cookie->def->select_cache(cookie->parent->netfs_data,  in fscache_select_cache_for_object()
138 					cookie->netfs_data);  in fscache_select_cache_for_object()
142 	if (tag == ERR_PTR(-ENOMEM)) {  in fscache_select_cache_for_object()
147 	if (!tag->cache) {  in fscache_select_cache_for_object()
152 	if (test_bit(FSCACHE_IOERROR, &tag->cache->flags))  in fscache_select_cache_for_object()
155 	_leave(" = %s [specific]", tag->name);  in fscache_select_cache_for_object()
156 	return tag->cache;  in fscache_select_cache_for_object()
159 	/* netfs has no preference - just select first cache */  in fscache_select_cache_for_object()
160 	cache = list_entry(fscache_cache_list.next,  in fscache_select_cache_for_object()
162 	_leave(" = %s [first]", cache->tag->name);  in fscache_select_cache_for_object()
163 	return cache;  in fscache_select_cache_for_object()
167  * fscache_init_cache - Initialise a cache record
168  * @cache: The cache record to be initialised
169  * @ops: The cache operations to be installed in that record
171  * @...: sprintf-style arguments
173  * Initialise a record of a cache and fill in the name.
175  * See Documentation/filesystems/caching/backend-api.rst for a complete
178 void fscache_init_cache(struct fscache_cache *cache,  in fscache_init_cache()  argument
185 	memset(cache, 0, sizeof(*cache));  in fscache_init_cache()
187 	cache->ops = ops;  in fscache_init_cache()
190 	vsnprintf(cache->identifier, sizeof(cache->identifier), idfmt, va);  in fscache_init_cache()
193 	INIT_WORK(&cache->op_gc, fscache_operation_gc);  in fscache_init_cache()
194 	INIT_LIST_HEAD(&cache->link);  in fscache_init_cache()
195 	INIT_LIST_HEAD(&cache->object_list);  in fscache_init_cache()
196 	INIT_LIST_HEAD(&cache->op_gc_list);  in fscache_init_cache()
197 	spin_lock_init(&cache->object_list_lock);  in fscache_init_cache()
198 	spin_lock_init(&cache->op_gc_list_lock);  in fscache_init_cache()
203  * fscache_add_cache - Declare a cache as being open for business
204  * @cache: The record describing the cache
205  * @ifsdef: The record of the cache object describing the top-level index
206  * @tagname: The tag describing this cache
208  * Add a cache to the system, making it available for netfs's to use.
210  * See Documentation/filesystems/caching/backend-api.rst for a complete
213 int fscache_add_cache(struct fscache_cache *cache,  in fscache_add_cache()  argument
219 	ASSERTCMP(ifsdef->cookie, ==, &fscache_fsdef_index);  in fscache_add_cache()
220 	BUG_ON(!cache->ops);  in fscache_add_cache()
223 	cache->flags = 0;  in fscache_add_cache()
224 	ifsdef->event_mask =  in fscache_add_cache()
225 		((1 << NR_FSCACHE_OBJECT_EVENTS) - 1) &  in fscache_add_cache()
227 	__set_bit(FSCACHE_OBJECT_IS_AVAILABLE, &ifsdef->flags);  in fscache_add_cache()
230 		tagname = cache->identifier;  in fscache_add_cache()
234 	_enter("{%s.%s},,%s", cache->ops->name, cache->identifier, tagname);  in fscache_add_cache()
236 	/* we use the cache tag to uniquely identify caches */  in fscache_add_cache()
241 	if (test_and_set_bit(FSCACHE_TAG_RESERVED, &tag->flags))  in fscache_add_cache()
244 	cache->kobj = kobject_create_and_add(tagname, fscache_root);  in fscache_add_cache()
245 	if (!cache->kobj)  in fscache_add_cache()
248 	ifsdef->cache = cache;  in fscache_add_cache()
249 	cache->fsdef = ifsdef;  in fscache_add_cache()
253 	tag->cache = cache;  in fscache_add_cache()
254 	cache->tag = tag;  in fscache_add_cache()
256 	/* add the cache to the list */  in fscache_add_cache()
257 	list_add(&cache->link, &fscache_cache_list);  in fscache_add_cache()
259 	/* add the cache's netfs definition index object to the cache's  in fscache_add_cache()
261 	spin_lock(&cache->object_list_lock);  in fscache_add_cache()
262 	list_add_tail(&ifsdef->cache_link, &cache->object_list);  in fscache_add_cache()
263 	spin_unlock(&cache->object_list_lock);  in fscache_add_cache()
265 	/* add the cache's netfs definition index object to the top level index  in fscache_add_cache()
269 	hlist_add_head(&ifsdef->cookie_link,  in fscache_add_cache()
278 	pr_notice("Cache \"%s\" added (type %s)\n",  in fscache_add_cache()
279 		  cache->tag->name, cache->ops->name);  in fscache_add_cache()
280 	kobject_uevent(cache->kobj, KOBJ_ADD);  in fscache_add_cache()
282 	_leave(" = 0 [%s]", cache->identifier);  in fscache_add_cache()
286 	pr_err("Cache tag '%s' already in use\n", tagname);  in fscache_add_cache()
288 	_leave(" = -EXIST");  in fscache_add_cache()
289 	return -EEXIST;  in fscache_add_cache()
293 	_leave(" = -EINVAL");  in fscache_add_cache()
294 	return -EINVAL;  in fscache_add_cache()
297 	_leave(" = -ENOMEM");  in fscache_add_cache()
298 	return -ENOMEM;  in fscache_add_cache()
303  * fscache_io_error - Note a cache I/O error
304  * @cache: The record describing the cache
306  * Note that an I/O error occurred in a cache and that it should no longer be
309  * See Documentation/filesystems/caching/backend-api.rst for a complete
312 void fscache_io_error(struct fscache_cache *cache)  in fscache_io_error()  argument
314 	if (!test_and_set_bit(FSCACHE_IOERROR, &cache->flags))  in fscache_io_error()
315 		pr_err("Cache '%s' stopped due to I/O error\n",  in fscache_io_error()
316 		       cache->ops->name);  in fscache_io_error()
321  * request withdrawal of all the objects in a cache
322  * - all the objects being withdrawn are moved onto the supplied list
324 static void fscache_withdraw_all_objects(struct fscache_cache *cache,  in fscache_withdraw_all_objects()  argument
329 	while (!list_empty(&cache->object_list)) {  in fscache_withdraw_all_objects()
330 		spin_lock(&cache->object_list_lock);  in fscache_withdraw_all_objects()
332 		if (!list_empty(&cache->object_list)) {  in fscache_withdraw_all_objects()
333 			object = list_entry(cache->object_list.next,  in fscache_withdraw_all_objects()
335 			list_move_tail(&object->cache_link, dying_objects);  in fscache_withdraw_all_objects()
337 			_debug("withdraw %x", object->cookie->debug_id);  in fscache_withdraw_all_objects()
345 		spin_unlock(&cache->object_list_lock);  in fscache_withdraw_all_objects()
351  * fscache_withdraw_cache - Withdraw a cache from the active service
352  * @cache: The record describing the cache
354  * Withdraw a cache from service, unbinding all its cache objects from the
357  * See Documentation/filesystems/caching/backend-api.rst for a complete
360 void fscache_withdraw_cache(struct fscache_cache *cache)  in fscache_withdraw_cache()  argument
366 	pr_notice("Withdrawing cache \"%s\"\n",  in fscache_withdraw_cache()
367 		  cache->tag->name);  in fscache_withdraw_cache()
369 	/* make the cache unavailable for cookie acquisition */  in fscache_withdraw_cache()
370 	if (test_and_set_bit(FSCACHE_CACHE_WITHDRAWN, &cache->flags))  in fscache_withdraw_cache()
374 	list_del_init(&cache->link);  in fscache_withdraw_cache()
375 	cache->tag->cache = NULL;  in fscache_withdraw_cache()
381 	cache->ops->sync_cache(cache);  in fscache_withdraw_cache()
384 	/* dissociate all the netfs pages backed by this cache from the block  in fscache_withdraw_cache()
385 	 * mappings in the cache */  in fscache_withdraw_cache()
387 	cache->ops->dissociate_pages(cache);  in fscache_withdraw_cache()
391 	 * cache - which we do by passing them off to thread pool to be  in fscache_withdraw_cache()
395 	fscache_withdraw_all_objects(cache, &dying_objects);  in fscache_withdraw_cache()
401 		   atomic_read(&cache->object_count) == 0);  in fscache_withdraw_cache()
404 		   list_empty(&cache->object_list));  in fscache_withdraw_cache()
408 	kobject_put(cache->kobj);  in fscache_withdraw_cache()
410 	clear_bit(FSCACHE_TAG_RESERVED, &cache->tag->flags);  in fscache_withdraw_cache()
411 	fscache_release_cache_tag(cache->tag);  in fscache_withdraw_cache()
412 	cache->tag = NULL;  in fscache_withdraw_cache()