1 /* FS-Cache cache handling
12 #define FSCACHE_DEBUG_LEVEL CACHE
25  * look up a cache tag
71  * release a reference to a cache tag
90  * select a cache in which to store an object
91  * - the cache addremove semaphore must be at least read-locked by the caller
99 	struct fscache_cache *cache;  in fscache_select_cache_for_object()  local
104 		_leave(" = NULL [no cache]");  in fscache_select_cache_for_object()
108 	/* we check the parent to determine the cache to use */  in fscache_select_cache_for_object()
112 	 * cache */  in fscache_select_cache_for_object()
117 		cache = object->cache;  in fscache_select_cache_for_object()
119 		    test_bit(FSCACHE_IOERROR, &cache->flags))  in fscache_select_cache_for_object()
120 			cache = NULL;  in fscache_select_cache_for_object()
123 		_leave(" = %p [parent]", cache);  in fscache_select_cache_for_object()
124 		return cache;  in fscache_select_cache_for_object()
151 	if (!tag->cache) {  in fscache_select_cache_for_object()
156 	if (test_bit(FSCACHE_IOERROR, &tag->cache->flags))  in fscache_select_cache_for_object()
159 	_leave(" = %p [specific]", tag->cache);  in fscache_select_cache_for_object()
160 	return tag->cache;  in fscache_select_cache_for_object()
163 	/* netfs has no preference - just select first cache */  in fscache_select_cache_for_object()
164 	cache = list_entry(fscache_cache_list.next,  in fscache_select_cache_for_object()
166 	_leave(" = %p [first]", cache);  in fscache_select_cache_for_object()
167 	return cache;  in fscache_select_cache_for_object()
171  * fscache_init_cache - Initialise a cache record
172  * @cache: The cache record to be initialised
173  * @ops: The cache operations to be installed in that record
177  * Initialise a record of a cache and fill in the name.
182 void fscache_init_cache(struct fscache_cache *cache,  in fscache_init_cache()  argument
189 	memset(cache, 0, sizeof(*cache));  in fscache_init_cache()
191 	cache->ops = ops;  in fscache_init_cache()
194 	vsnprintf(cache->identifier, sizeof(cache->identifier), idfmt, va);  in fscache_init_cache()
197 	INIT_WORK(&cache->op_gc, fscache_operation_gc);  in fscache_init_cache()
198 	INIT_LIST_HEAD(&cache->link);  in fscache_init_cache()
199 	INIT_LIST_HEAD(&cache->object_list);  in fscache_init_cache()
200 	INIT_LIST_HEAD(&cache->op_gc_list);  in fscache_init_cache()
201 	spin_lock_init(&cache->object_list_lock);  in fscache_init_cache()
202 	spin_lock_init(&cache->op_gc_list_lock);  in fscache_init_cache()
207  * fscache_add_cache - Declare a cache as being open for business
208  * @cache: The record describing the cache
209  * @ifsdef: The record of the cache object describing the top-level index
210  * @tagname: The tag describing this cache
212  * Add a cache to the system, making it available for netfs's to use.
217 int fscache_add_cache(struct fscache_cache *cache,  in fscache_add_cache()  argument
224 	BUG_ON(!cache->ops);  in fscache_add_cache()
227 	cache->flags = 0;  in fscache_add_cache()
234 		tagname = cache->identifier;  in fscache_add_cache()
238 	_enter("{%s.%s},,%s", cache->ops->name, cache->identifier, tagname);  in fscache_add_cache()
240 	/* we use the cache tag to uniquely identify caches */  in fscache_add_cache()
248 	cache->kobj = kobject_create_and_add(tagname, fscache_root);  in fscache_add_cache()
249 	if (!cache->kobj)  in fscache_add_cache()
252 	ifsdef->cache = cache;  in fscache_add_cache()
253 	cache->fsdef = ifsdef;  in fscache_add_cache()
257 	tag->cache = cache;  in fscache_add_cache()
258 	cache->tag = tag;  in fscache_add_cache()
260 	/* add the cache to the list */  in fscache_add_cache()
261 	list_add(&cache->link, &fscache_cache_list);  in fscache_add_cache()
263 	/* add the cache's netfs definition index object to the cache's  in fscache_add_cache()
265 	spin_lock(&cache->object_list_lock);  in fscache_add_cache()
266 	list_add_tail(&ifsdef->cache_link, &cache->object_list);  in fscache_add_cache()
267 	spin_unlock(&cache->object_list_lock);  in fscache_add_cache()
270 	/* add the cache's netfs definition index object to the top level index  in fscache_add_cache()
283 	pr_notice("Cache \"%s\" added (type %s)\n",  in fscache_add_cache()
284 		  cache->tag->name, cache->ops->name);  in fscache_add_cache()
285 	kobject_uevent(cache->kobj, KOBJ_ADD);  in fscache_add_cache()
287 	_leave(" = 0 [%s]", cache->identifier);  in fscache_add_cache()
291 	pr_err("Cache tag '%s' already in use\n", tagname);  in fscache_add_cache()
308  * fscache_io_error - Note a cache I/O error
309  * @cache: The record describing the cache
311  * Note that an I/O error occurred in a cache and that it should no longer be
317 void fscache_io_error(struct fscache_cache *cache)  in fscache_io_error()  argument
319 	if (!test_and_set_bit(FSCACHE_IOERROR, &cache->flags))  in fscache_io_error()
320 		pr_err("Cache '%s' stopped due to I/O error\n",  in fscache_io_error()
321 		       cache->ops->name);  in fscache_io_error()
326  * request withdrawal of all the objects in a cache
329 static void fscache_withdraw_all_objects(struct fscache_cache *cache,  in fscache_withdraw_all_objects()  argument
334 	while (!list_empty(&cache->object_list)) {  in fscache_withdraw_all_objects()
335 		spin_lock(&cache->object_list_lock);  in fscache_withdraw_all_objects()
337 		if (!list_empty(&cache->object_list)) {  in fscache_withdraw_all_objects()
338 			object = list_entry(cache->object_list.next,  in fscache_withdraw_all_objects()
350 		spin_unlock(&cache->object_list_lock);  in fscache_withdraw_all_objects()
356  * fscache_withdraw_cache - Withdraw a cache from the active service
357  * @cache: The record describing the cache
359  * Withdraw a cache from service, unbinding all its cache objects from the
365 void fscache_withdraw_cache(struct fscache_cache *cache)  in fscache_withdraw_cache()  argument
371 	pr_notice("Withdrawing cache \"%s\"\n",  in fscache_withdraw_cache()
372 		  cache->tag->name);  in fscache_withdraw_cache()
374 	/* make the cache unavailable for cookie acquisition */  in fscache_withdraw_cache()
375 	if (test_and_set_bit(FSCACHE_CACHE_WITHDRAWN, &cache->flags))  in fscache_withdraw_cache()
379 	list_del_init(&cache->link);  in fscache_withdraw_cache()
380 	cache->tag->cache = NULL;  in fscache_withdraw_cache()
386 	cache->ops->sync_cache(cache);  in fscache_withdraw_cache()
389 	/* dissociate all the netfs pages backed by this cache from the block  in fscache_withdraw_cache()
390 	 * mappings in the cache */  in fscache_withdraw_cache()
392 	cache->ops->dissociate_pages(cache);  in fscache_withdraw_cache()
396 	 * cache - which we do by passing them off to thread pool to be  in fscache_withdraw_cache()
400 	fscache_withdraw_all_objects(cache, &dying_objects);  in fscache_withdraw_cache()
406 		   atomic_read(&cache->object_count) == 0);  in fscache_withdraw_cache()
409 		   list_empty(&cache->object_list));  in fscache_withdraw_cache()
413 	kobject_put(cache->kobj);  in fscache_withdraw_cache()
415 	clear_bit(FSCACHE_TAG_RESERVED, &cache->tag->flags);  in fscache_withdraw_cache()
416 	fscache_release_cache_tag(cache->tag);  in fscache_withdraw_cache()
417 	cache->tag = NULL;  in fscache_withdraw_cache()