21  * identifies a cache entry.
24  * and a special "delete entry with given key-value pair" operation. Fixed
63  * mb_cache_entry_create - create entry in cache
64  * @cache - cache where the entry should be created
65  * @mask - gfp mask with which the entry should be allocated
66  * @key - key of the entry
67  * @value - value of the entry
68  * @reusable - is the entry reusable by others?
70  * Creates entry in @cache with key @key and value @value. The function returns
71  * -EBUSY if entry with the same key and value already exists in cache.
77 	struct mb_cache_entry *entry, *dup;  in mb_cache_entry_create()  local
88 	entry = kmem_cache_alloc(mb_entry_cache, mask);  in mb_cache_entry_create()
89 	if (!entry)  in mb_cache_entry_create()
92 	INIT_LIST_HEAD(&entry->e_list);  in mb_cache_entry_create()
94 	 * We create entry with two references. One reference is kept by the  in mb_cache_entry_create()
96 	 * mb_cache_entry_delete_or_get() until the entry is fully setup. This  in mb_cache_entry_create()
100 	atomic_set(&entry->e_refcnt, 2);  in mb_cache_entry_create()
101 	entry->e_key = key;  in mb_cache_entry_create()
102 	entry->e_value = value;  in mb_cache_entry_create()
103 	entry->e_flags = 0;  in mb_cache_entry_create()
105 		set_bit(MBE_REUSABLE_B, &entry->e_flags);  in mb_cache_entry_create()
111 			kmem_cache_free(mb_entry_cache, entry);  in mb_cache_entry_create()
115 	hlist_bl_add_head(&entry->e_hash_list, head);  in mb_cache_entry_create()
118 	list_add_tail(&entry->e_list, &cache->c_list);  in mb_cache_entry_create()
121 	mb_cache_entry_put(cache, entry);  in mb_cache_entry_create()
127 void __mb_cache_entry_free(struct mb_cache *cache, struct mb_cache_entry *entry)  in __mb_cache_entry_free()  argument
131 	head = mb_cache_entry_head(cache, entry->e_key);  in __mb_cache_entry_free()
133 	hlist_bl_del(&entry->e_hash_list);  in __mb_cache_entry_free()
135 	kmem_cache_free(mb_entry_cache, entry);  in __mb_cache_entry_free()
140  * mb_cache_entry_wait_unused - wait to be the last user of the entry
142  * @entry - entry to work on
144  * Wait to be the last user of the entry.
146 void mb_cache_entry_wait_unused(struct mb_cache_entry *entry)  in mb_cache_entry_wait_unused()  argument
148 	wait_var_event(&entry->e_refcnt, atomic_read(&entry->e_refcnt) <= 2);  in mb_cache_entry_wait_unused()
153 					   struct mb_cache_entry *entry,  in __entry_find()  argument
156 	struct mb_cache_entry *old_entry = entry;  in __entry_find()
162 	if (entry && !hlist_bl_unhashed(&entry->e_hash_list))  in __entry_find()
163 		node = entry->e_hash_list.next;  in __entry_find()
167 		entry = hlist_bl_entry(node, struct mb_cache_entry,  in __entry_find()
169 		if (entry->e_key == key &&  in __entry_find()
170 		    test_bit(MBE_REUSABLE_B, &entry->e_flags) &&  in __entry_find()
171 		    atomic_inc_not_zero(&entry->e_refcnt))  in __entry_find()
175 	entry = NULL;  in __entry_find()
181 	return entry;  in __entry_find()
185  * mb_cache_entry_find_first - find the first reusable entry with the given key
189  * Search in @cache for a reusable entry with key @key. Grabs reference to the
190  * first reusable entry found and returns the entry.
200  * mb_cache_entry_find_next - find next reusable entry with the same key
202  * @entry: entry to start search from
204  * Finds next reusable entry in the hash chain which has the same key as @entry.
205  * If @entry is unhashed (which can happen when deletion of entry races with the
206  * search), finds the first reusable entry in the hash chain. The function drops
207  * reference to @entry and returns with a reference to the found entry.
210 						struct mb_cache_entry *entry)  in mb_cache_entry_find_next()  argument
212 	return __entry_find(cache, entry, entry->e_key);  in mb_cache_entry_find_next()
217  * mb_cache_entry_get - get a cache entry by value (and key)
227 	struct mb_cache_entry *entry;  in mb_cache_entry_get()  local
231 	hlist_bl_for_each_entry(entry, node, head, e_hash_list) {  in mb_cache_entry_get()
232 		if (entry->e_key == key && entry->e_value == value &&  in mb_cache_entry_get()
233 		    atomic_inc_not_zero(&entry->e_refcnt))  in mb_cache_entry_get()
236 	entry = NULL;  in mb_cache_entry_get()
239 	return entry;  in mb_cache_entry_get()
243 /* mb_cache_entry_delete_or_get - remove a cache entry if it has no users
248  * Remove entry from cache @cache with key @key and value @value. The removal
249  * happens only if the entry is unused. The function returns NULL in case the
250  * entry was successfully removed or there's no entry in cache. Otherwise the
251  * function grabs reference of the entry that we failed to delete because it
257 	struct mb_cache_entry *entry;  in mb_cache_entry_delete_or_get()  local
259 	entry = mb_cache_entry_get(cache, key, value);  in mb_cache_entry_delete_or_get()
260 	if (!entry)  in mb_cache_entry_delete_or_get()
267 	if (atomic_cmpxchg(&entry->e_refcnt, 2, 0) != 2)  in mb_cache_entry_delete_or_get()
268 		return entry;  in mb_cache_entry_delete_or_get()
271 	if (!list_empty(&entry->e_list))  in mb_cache_entry_delete_or_get()
272 		list_del_init(&entry->e_list);  in mb_cache_entry_delete_or_get()
275 	__mb_cache_entry_free(cache, entry);  in mb_cache_entry_delete_or_get()
280 /* mb_cache_entry_touch - cache entry got used
281  * @cache - cache the entry belongs to
282  * @entry - entry that got used
284  * Marks entry as used to give hit higher chances of surviving in cache.
287 			  struct mb_cache_entry *entry)  in mb_cache_entry_touch()  argument
289 	set_bit(MBE_REFERENCED_B, &entry->e_flags);  in mb_cache_entry_touch()
305 	struct mb_cache_entry *entry;  in mb_cache_shrink()  local
310 		entry = list_first_entry(&cache->c_list,  in mb_cache_shrink()
313 		if (test_bit(MBE_REFERENCED_B, &entry->e_flags) ||  in mb_cache_shrink()
314 		    atomic_cmpxchg(&entry->e_refcnt, 1, 0) != 1) {  in mb_cache_shrink()
315 			clear_bit(MBE_REFERENCED_B, &entry->e_flags);  in mb_cache_shrink()
316 			list_move_tail(&entry->e_list, &cache->c_list);  in mb_cache_shrink()
319 		list_del_init(&entry->e_list);  in mb_cache_shrink()
322 		__mb_cache_entry_free(cache, entry);  in mb_cache_shrink()
409 	struct mb_cache_entry *entry, *next;  in mb_cache_destroy()  local
417 	list_for_each_entry_safe(entry, next, &cache->c_list, e_list) {  in mb_cache_destroy()
418 		list_del(&entry->e_list);  in mb_cache_destroy()
419 		WARN_ON(atomic_read(&entry->e_refcnt) != 1);  in mb_cache_destroy()
420 		mb_cache_entry_put(cache, entry);  in mb_cache_destroy()