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_reusable = reusable;  in mb_cache_entry_create()
104 	entry->e_referenced = 0;  in mb_cache_entry_create()
110 			kmem_cache_free(mb_entry_cache, entry);  in mb_cache_entry_create()
114 	hlist_bl_add_head(&entry->e_hash_list, head);  in mb_cache_entry_create()
117 	list_add_tail(&entry->e_list, &cache->c_list);  in mb_cache_entry_create()
120 	mb_cache_entry_put(cache, entry);  in mb_cache_entry_create()
126 void __mb_cache_entry_free(struct mb_cache *cache, struct mb_cache_entry *entry)  in __mb_cache_entry_free()  argument
130 	head = mb_cache_entry_head(cache, entry->e_key);  in __mb_cache_entry_free()
132 	hlist_bl_del(&entry->e_hash_list);  in __mb_cache_entry_free()
134 	kmem_cache_free(mb_entry_cache, entry);  in __mb_cache_entry_free()
139  * mb_cache_entry_wait_unused - wait to be the last user of the entry
141  * @entry - entry to work on
143  * Wait to be the last user of the entry.
145 void mb_cache_entry_wait_unused(struct mb_cache_entry *entry)  in mb_cache_entry_wait_unused()  argument
147 	wait_var_event(&entry->e_refcnt, atomic_read(&entry->e_refcnt) <= 2);  in mb_cache_entry_wait_unused()
152 					   struct mb_cache_entry *entry,  in __entry_find()  argument
155 	struct mb_cache_entry *old_entry = entry;  in __entry_find()
161 	if (entry && !hlist_bl_unhashed(&entry->e_hash_list))  in __entry_find()
162 		node = entry->e_hash_list.next;  in __entry_find()
166 		entry = hlist_bl_entry(node, struct mb_cache_entry,  in __entry_find()
168 		if (entry->e_key == key && entry->e_reusable &&  in __entry_find()
169 		    atomic_inc_not_zero(&entry->e_refcnt))  in __entry_find()
173 	entry = NULL;  in __entry_find()
179 	return entry;  in __entry_find()
183  * mb_cache_entry_find_first - find the first reusable entry with the given key
187  * Search in @cache for a reusable entry with key @key. Grabs reference to the
188  * first reusable entry found and returns the entry.
198  * mb_cache_entry_find_next - find next reusable entry with the same key
200  * @entry: entry to start search from
202  * Finds next reusable entry in the hash chain which has the same key as @entry.
203  * If @entry is unhashed (which can happen when deletion of entry races with the
204  * search), finds the first reusable entry in the hash chain. The function drops
205  * reference to @entry and returns with a reference to the found entry.
208 						struct mb_cache_entry *entry)  in mb_cache_entry_find_next()  argument
210 	return __entry_find(cache, entry, entry->e_key);  in mb_cache_entry_find_next()
215  * mb_cache_entry_get - get a cache entry by value (and key)
225 	struct mb_cache_entry *entry;  in mb_cache_entry_get()  local
229 	hlist_bl_for_each_entry(entry, node, head, e_hash_list) {  in mb_cache_entry_get()
230 		if (entry->e_key == key && entry->e_value == value &&  in mb_cache_entry_get()
231 		    atomic_inc_not_zero(&entry->e_refcnt))  in mb_cache_entry_get()
234 	entry = NULL;  in mb_cache_entry_get()
237 	return entry;  in mb_cache_entry_get()
241 /* mb_cache_entry_delete_or_get - remove a cache entry if it has no users
246  * Remove entry from cache @cache with key @key and value @value. The removal
247  * happens only if the entry is unused. The function returns NULL in case the
248  * entry was successfully removed or there's no entry in cache. Otherwise the
249  * function grabs reference of the entry that we failed to delete because it
255 	struct mb_cache_entry *entry;  in mb_cache_entry_delete_or_get()  local
257 	entry = mb_cache_entry_get(cache, key, value);  in mb_cache_entry_delete_or_get()
258 	if (!entry)  in mb_cache_entry_delete_or_get()
265 	if (atomic_cmpxchg(&entry->e_refcnt, 2, 0) != 2)  in mb_cache_entry_delete_or_get()
266 		return entry;  in mb_cache_entry_delete_or_get()
269 	if (!list_empty(&entry->e_list))  in mb_cache_entry_delete_or_get()
270 		list_del_init(&entry->e_list);  in mb_cache_entry_delete_or_get()
273 	__mb_cache_entry_free(cache, entry);  in mb_cache_entry_delete_or_get()
278 /* mb_cache_entry_touch - cache entry got used
279  * @cache - cache the entry belongs to
280  * @entry - entry that got used
282  * Marks entry as used to give hit higher chances of surviving in cache.
285 			  struct mb_cache_entry *entry)  in mb_cache_entry_touch()  argument
287 	entry->e_referenced = 1;  in mb_cache_entry_touch()
304 	struct mb_cache_entry *entry;  in mb_cache_shrink()  local
309 		entry = list_first_entry(&cache->c_list,  in mb_cache_shrink()
312 		if (entry->e_referenced ||  in mb_cache_shrink()
313 		    atomic_cmpxchg(&entry->e_refcnt, 1, 0) != 1) {  in mb_cache_shrink()
314 			entry->e_referenced = 0;  in mb_cache_shrink()
315 			list_move_tail(&entry->e_list, &cache->c_list);  in mb_cache_shrink()
318 		list_del_init(&entry->e_list);  in mb_cache_shrink()
321 		__mb_cache_entry_free(cache, entry);  in mb_cache_shrink()
405 	struct mb_cache_entry *entry, *next;  in mb_cache_destroy()  local
413 	list_for_each_entry_safe(entry, next, &cache->c_list, e_list) {  in mb_cache_destroy()
414 		list_del(&entry->e_list);  in mb_cache_destroy()
415 		WARN_ON(atomic_read(&entry->e_refcnt) != 1);  in mb_cache_destroy()
416 		mb_cache_entry_put(cache, entry);  in mb_cache_destroy()