blob: bf41e2e72c1883b7fba884a8f7006ecc50bcf768 [file] [log] [blame]
Jan Karaf9a61eb2016-02-22 11:49:09 -05001#include <linux/spinlock.h>
2#include <linux/slab.h>
3#include <linux/list.h>
4#include <linux/list_bl.h>
5#include <linux/module.h>
6#include <linux/sched.h>
Jan Karac2f31402016-02-22 12:33:03 -05007#include <linux/workqueue.h>
Jan Kara7a2508e2016-02-22 22:35:22 -05008#include <linux/mbcache.h>
Jan Karaf9a61eb2016-02-22 11:49:09 -05009
10/*
11 * Mbcache is a simple key-value store. Keys need not be unique, however
12 * key-value pairs are expected to be unique (we use this fact in
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -040013 * mb_cache_entry_delete()).
Jan Karaf9a61eb2016-02-22 11:49:09 -050014 *
15 * Ext2 and ext4 use this cache for deduplication of extended attribute blocks.
Tahsin Erdogandec214d2017-06-22 11:44:55 -040016 * Ext4 also uses it for deduplication of xattr values stored in inodes.
17 * They use hash of data as a key and provide a value that may represent a
18 * block or inode number. That's why keys need not be unique (hash of different
19 * data may be the same). However user provided value always uniquely
20 * identifies a cache entry.
Jan Karaf9a61eb2016-02-22 11:49:09 -050021 *
22 * We provide functions for creation and removal of entries, search by key,
23 * and a special "delete entry with given key-value pair" operation. Fixed
24 * size hash table is used for fast key lookups.
25 */
26
Jan Kara7a2508e2016-02-22 22:35:22 -050027struct mb_cache {
Jan Karaf9a61eb2016-02-22 11:49:09 -050028 /* Hash table of entries */
29 struct hlist_bl_head *c_hash;
30 /* log2 of hash table size */
31 int c_bucket_bits;
Jan Karac2f31402016-02-22 12:33:03 -050032 /* Maximum entries in cache to avoid degrading hash too much */
Eric Biggers132d4e22016-12-03 15:43:48 -050033 unsigned long c_max_entries;
Jan Karaf0c8b462016-02-22 18:23:47 -050034 /* Protects c_list, c_entry_count */
35 spinlock_t c_list_lock;
36 struct list_head c_list;
Jan Karaf9a61eb2016-02-22 11:49:09 -050037 /* Number of entries in cache */
38 unsigned long c_entry_count;
39 struct shrinker c_shrink;
Jan Karac2f31402016-02-22 12:33:03 -050040 /* Work for shrinking when the cache has too many entries */
41 struct work_struct c_shrink_work;
Jan Karaf9a61eb2016-02-22 11:49:09 -050042};
43
Jan Kara7a2508e2016-02-22 22:35:22 -050044static struct kmem_cache *mb_entry_cache;
Jan Karaf9a61eb2016-02-22 11:49:09 -050045
Jan Kara7a2508e2016-02-22 22:35:22 -050046static unsigned long mb_cache_shrink(struct mb_cache *cache,
Eric Biggers132d4e22016-12-03 15:43:48 -050047 unsigned long nr_to_scan);
Jan Karac2f31402016-02-22 12:33:03 -050048
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -050049static inline struct hlist_bl_head *mb_cache_entry_head(struct mb_cache *cache,
50 u32 key)
Jan Karaf0c8b462016-02-22 18:23:47 -050051{
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -050052 return &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
Jan Karaf0c8b462016-02-22 18:23:47 -050053}
54
Jan Karac2f31402016-02-22 12:33:03 -050055/*
56 * Number of entries to reclaim synchronously when there are too many entries
57 * in cache
58 */
59#define SYNC_SHRINK_BATCH 64
60
Jan Karaf9a61eb2016-02-22 11:49:09 -050061/*
Jan Kara7a2508e2016-02-22 22:35:22 -050062 * mb_cache_entry_create - create entry in cache
Jan Karaf9a61eb2016-02-22 11:49:09 -050063 * @cache - cache where the entry should be created
64 * @mask - gfp mask with which the entry should be allocated
65 * @key - key of the entry
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -040066 * @value - value of the entry
67 * @reusable - is the entry reusable by others?
Jan Karaf9a61eb2016-02-22 11:49:09 -050068 *
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -040069 * Creates entry in @cache with key @key and value @value. The function returns
70 * -EBUSY if entry with the same key and value already exists in cache.
71 * Otherwise 0 is returned.
Jan Karaf9a61eb2016-02-22 11:49:09 -050072 */
Jan Kara7a2508e2016-02-22 22:35:22 -050073int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -040074 u64 value, bool reusable)
Jan Karaf9a61eb2016-02-22 11:49:09 -050075{
Jan Kara7a2508e2016-02-22 22:35:22 -050076 struct mb_cache_entry *entry, *dup;
Jan Karaf9a61eb2016-02-22 11:49:09 -050077 struct hlist_bl_node *dup_node;
78 struct hlist_bl_head *head;
79
Jan Karac2f31402016-02-22 12:33:03 -050080 /* Schedule background reclaim if there are too many entries */
81 if (cache->c_entry_count >= cache->c_max_entries)
82 schedule_work(&cache->c_shrink_work);
83 /* Do some sync reclaim if background reclaim cannot keep up */
84 if (cache->c_entry_count >= 2*cache->c_max_entries)
Jan Kara7a2508e2016-02-22 22:35:22 -050085 mb_cache_shrink(cache, SYNC_SHRINK_BATCH);
Jan Karac2f31402016-02-22 12:33:03 -050086
Jan Kara7a2508e2016-02-22 22:35:22 -050087 entry = kmem_cache_alloc(mb_entry_cache, mask);
Jan Karaf9a61eb2016-02-22 11:49:09 -050088 if (!entry)
89 return -ENOMEM;
90
Jan Karaf0c8b462016-02-22 18:23:47 -050091 INIT_LIST_HEAD(&entry->e_list);
Jan Karaf9a61eb2016-02-22 11:49:09 -050092 /* One ref for hash, one ref returned */
93 atomic_set(&entry->e_refcnt, 1);
94 entry->e_key = key;
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -040095 entry->e_value = value;
Andreas Gruenbacher6048c642016-02-22 22:44:04 -050096 entry->e_reusable = reusable;
Alexander Potapenko3876bbe2018-01-07 16:22:35 -050097 entry->e_referenced = 0;
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -050098 head = mb_cache_entry_head(cache, key);
Jan Karaf9a61eb2016-02-22 11:49:09 -050099 hlist_bl_lock(head);
100 hlist_bl_for_each_entry(dup, dup_node, head, e_hash_list) {
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400101 if (dup->e_key == key && dup->e_value == value) {
Jan Karaf9a61eb2016-02-22 11:49:09 -0500102 hlist_bl_unlock(head);
Jan Kara7a2508e2016-02-22 22:35:22 -0500103 kmem_cache_free(mb_entry_cache, entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500104 return -EBUSY;
105 }
106 }
107 hlist_bl_add_head(&entry->e_hash_list, head);
108 hlist_bl_unlock(head);
109
Jan Karaf0c8b462016-02-22 18:23:47 -0500110 spin_lock(&cache->c_list_lock);
111 list_add_tail(&entry->e_list, &cache->c_list);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500112 /* Grab ref for LRU list */
113 atomic_inc(&entry->e_refcnt);
114 cache->c_entry_count++;
Jan Karaf0c8b462016-02-22 18:23:47 -0500115 spin_unlock(&cache->c_list_lock);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500116
117 return 0;
118}
Jan Kara7a2508e2016-02-22 22:35:22 -0500119EXPORT_SYMBOL(mb_cache_entry_create);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500120
Jan Kara7a2508e2016-02-22 22:35:22 -0500121void __mb_cache_entry_free(struct mb_cache_entry *entry)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500122{
Jan Kara7a2508e2016-02-22 22:35:22 -0500123 kmem_cache_free(mb_entry_cache, entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500124}
Jan Kara7a2508e2016-02-22 22:35:22 -0500125EXPORT_SYMBOL(__mb_cache_entry_free);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500126
Jan Kara7a2508e2016-02-22 22:35:22 -0500127static struct mb_cache_entry *__entry_find(struct mb_cache *cache,
128 struct mb_cache_entry *entry,
129 u32 key)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500130{
Jan Kara7a2508e2016-02-22 22:35:22 -0500131 struct mb_cache_entry *old_entry = entry;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500132 struct hlist_bl_node *node;
133 struct hlist_bl_head *head;
134
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500135 head = mb_cache_entry_head(cache, key);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500136 hlist_bl_lock(head);
137 if (entry && !hlist_bl_unhashed(&entry->e_hash_list))
138 node = entry->e_hash_list.next;
139 else
140 node = hlist_bl_first(head);
141 while (node) {
Jan Kara7a2508e2016-02-22 22:35:22 -0500142 entry = hlist_bl_entry(node, struct mb_cache_entry,
Jan Karaf9a61eb2016-02-22 11:49:09 -0500143 e_hash_list);
Andreas Gruenbacher6048c642016-02-22 22:44:04 -0500144 if (entry->e_key == key && entry->e_reusable) {
Jan Karaf9a61eb2016-02-22 11:49:09 -0500145 atomic_inc(&entry->e_refcnt);
146 goto out;
147 }
148 node = node->next;
149 }
150 entry = NULL;
151out:
152 hlist_bl_unlock(head);
153 if (old_entry)
Jan Kara7a2508e2016-02-22 22:35:22 -0500154 mb_cache_entry_put(cache, old_entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500155
156 return entry;
157}
158
159/*
Eric Biggersb6496682016-12-03 15:55:01 -0500160 * mb_cache_entry_find_first - find the first reusable entry with the given key
Jan Karaf9a61eb2016-02-22 11:49:09 -0500161 * @cache: cache where we should search
162 * @key: key to look for
163 *
Eric Biggersb6496682016-12-03 15:55:01 -0500164 * Search in @cache for a reusable entry with key @key. Grabs reference to the
165 * first reusable entry found and returns the entry.
Jan Karaf9a61eb2016-02-22 11:49:09 -0500166 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500167struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache,
168 u32 key)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500169{
170 return __entry_find(cache, NULL, key);
171}
Jan Kara7a2508e2016-02-22 22:35:22 -0500172EXPORT_SYMBOL(mb_cache_entry_find_first);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500173
174/*
Eric Biggersb6496682016-12-03 15:55:01 -0500175 * mb_cache_entry_find_next - find next reusable entry with the same key
Jan Karaf9a61eb2016-02-22 11:49:09 -0500176 * @cache: cache where we should search
177 * @entry: entry to start search from
178 *
Eric Biggersb6496682016-12-03 15:55:01 -0500179 * Finds next reusable entry in the hash chain which has the same key as @entry.
180 * If @entry is unhashed (which can happen when deletion of entry races with the
181 * search), finds the first reusable entry in the hash chain. The function drops
182 * reference to @entry and returns with a reference to the found entry.
Jan Karaf9a61eb2016-02-22 11:49:09 -0500183 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500184struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache,
185 struct mb_cache_entry *entry)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500186{
187 return __entry_find(cache, entry, entry->e_key);
188}
Jan Kara7a2508e2016-02-22 22:35:22 -0500189EXPORT_SYMBOL(mb_cache_entry_find_next);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500190
Andreas Gruenbacher6048c642016-02-22 22:44:04 -0500191/*
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400192 * mb_cache_entry_get - get a cache entry by value (and key)
Andreas Gruenbacher6048c642016-02-22 22:44:04 -0500193 * @cache - cache we work with
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400194 * @key - key
195 * @value - value
Andreas Gruenbacher6048c642016-02-22 22:44:04 -0500196 */
197struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400198 u64 value)
Andreas Gruenbacher6048c642016-02-22 22:44:04 -0500199{
200 struct hlist_bl_node *node;
201 struct hlist_bl_head *head;
202 struct mb_cache_entry *entry;
203
204 head = mb_cache_entry_head(cache, key);
205 hlist_bl_lock(head);
206 hlist_bl_for_each_entry(entry, node, head, e_hash_list) {
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400207 if (entry->e_key == key && entry->e_value == value) {
Andreas Gruenbacher6048c642016-02-22 22:44:04 -0500208 atomic_inc(&entry->e_refcnt);
209 goto out;
210 }
211 }
212 entry = NULL;
213out:
214 hlist_bl_unlock(head);
215 return entry;
216}
217EXPORT_SYMBOL(mb_cache_entry_get);
218
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400219/* mb_cache_entry_delete - remove a cache entry
Jan Karaf9a61eb2016-02-22 11:49:09 -0500220 * @cache - cache we work with
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400221 * @key - key
222 * @value - value
Jan Karaf9a61eb2016-02-22 11:49:09 -0500223 *
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400224 * Remove entry from cache @cache with key @key and value @value.
Jan Karaf9a61eb2016-02-22 11:49:09 -0500225 */
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400226void mb_cache_entry_delete(struct mb_cache *cache, u32 key, u64 value)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500227{
228 struct hlist_bl_node *node;
229 struct hlist_bl_head *head;
Jan Kara7a2508e2016-02-22 22:35:22 -0500230 struct mb_cache_entry *entry;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500231
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500232 head = mb_cache_entry_head(cache, key);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500233 hlist_bl_lock(head);
234 hlist_bl_for_each_entry(entry, node, head, e_hash_list) {
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400235 if (entry->e_key == key && entry->e_value == value) {
Jan Karaf9a61eb2016-02-22 11:49:09 -0500236 /* We keep hash list reference to keep entry alive */
237 hlist_bl_del_init(&entry->e_hash_list);
238 hlist_bl_unlock(head);
Jan Karaf0c8b462016-02-22 18:23:47 -0500239 spin_lock(&cache->c_list_lock);
240 if (!list_empty(&entry->e_list)) {
241 list_del_init(&entry->e_list);
Jiang Biao9ee93ba2018-01-09 23:57:52 -0500242 if (!WARN_ONCE(cache->c_entry_count == 0,
243 "mbcache: attempt to decrement c_entry_count past zero"))
244 cache->c_entry_count--;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500245 atomic_dec(&entry->e_refcnt);
246 }
Jan Karaf0c8b462016-02-22 18:23:47 -0500247 spin_unlock(&cache->c_list_lock);
Jan Kara7a2508e2016-02-22 22:35:22 -0500248 mb_cache_entry_put(cache, entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500249 return;
250 }
251 }
252 hlist_bl_unlock(head);
253}
Tahsin Erdoganc07dfcb2017-06-22 10:29:53 -0400254EXPORT_SYMBOL(mb_cache_entry_delete);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500255
Jan Kara7a2508e2016-02-22 22:35:22 -0500256/* mb_cache_entry_touch - cache entry got used
Jan Karaf9a61eb2016-02-22 11:49:09 -0500257 * @cache - cache the entry belongs to
258 * @entry - entry that got used
259 *
Jan Karaf0c8b462016-02-22 18:23:47 -0500260 * Marks entry as used to give hit higher chances of surviving in cache.
Jan Karaf9a61eb2016-02-22 11:49:09 -0500261 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500262void mb_cache_entry_touch(struct mb_cache *cache,
263 struct mb_cache_entry *entry)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500264{
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500265 entry->e_referenced = 1;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500266}
Jan Kara7a2508e2016-02-22 22:35:22 -0500267EXPORT_SYMBOL(mb_cache_entry_touch);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500268
Jan Kara7a2508e2016-02-22 22:35:22 -0500269static unsigned long mb_cache_count(struct shrinker *shrink,
270 struct shrink_control *sc)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500271{
Jan Kara7a2508e2016-02-22 22:35:22 -0500272 struct mb_cache *cache = container_of(shrink, struct mb_cache,
273 c_shrink);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500274
275 return cache->c_entry_count;
276}
277
278/* Shrink number of entries in cache */
Jan Kara7a2508e2016-02-22 22:35:22 -0500279static unsigned long mb_cache_shrink(struct mb_cache *cache,
Eric Biggers132d4e22016-12-03 15:43:48 -0500280 unsigned long nr_to_scan)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500281{
Jan Kara7a2508e2016-02-22 22:35:22 -0500282 struct mb_cache_entry *entry;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500283 struct hlist_bl_head *head;
Eric Biggers132d4e22016-12-03 15:43:48 -0500284 unsigned long shrunk = 0;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500285
Jan Karaf0c8b462016-02-22 18:23:47 -0500286 spin_lock(&cache->c_list_lock);
287 while (nr_to_scan-- && !list_empty(&cache->c_list)) {
288 entry = list_first_entry(&cache->c_list,
Jan Kara7a2508e2016-02-22 22:35:22 -0500289 struct mb_cache_entry, e_list);
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500290 if (entry->e_referenced) {
291 entry->e_referenced = 0;
Eric Biggers918b7302016-12-03 15:13:15 -0500292 list_move_tail(&entry->e_list, &cache->c_list);
Jan Karaf0c8b462016-02-22 18:23:47 -0500293 continue;
294 }
295 list_del_init(&entry->e_list);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500296 cache->c_entry_count--;
297 /*
298 * We keep LRU list reference so that entry doesn't go away
299 * from under us.
300 */
Jan Karaf0c8b462016-02-22 18:23:47 -0500301 spin_unlock(&cache->c_list_lock);
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500302 head = mb_cache_entry_head(cache, entry->e_key);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500303 hlist_bl_lock(head);
304 if (!hlist_bl_unhashed(&entry->e_hash_list)) {
305 hlist_bl_del_init(&entry->e_hash_list);
306 atomic_dec(&entry->e_refcnt);
307 }
308 hlist_bl_unlock(head);
Jan Kara7a2508e2016-02-22 22:35:22 -0500309 if (mb_cache_entry_put(cache, entry))
Jan Karaf9a61eb2016-02-22 11:49:09 -0500310 shrunk++;
311 cond_resched();
Jan Karaf0c8b462016-02-22 18:23:47 -0500312 spin_lock(&cache->c_list_lock);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500313 }
Jan Karaf0c8b462016-02-22 18:23:47 -0500314 spin_unlock(&cache->c_list_lock);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500315
316 return shrunk;
317}
318
Jan Kara7a2508e2016-02-22 22:35:22 -0500319static unsigned long mb_cache_scan(struct shrinker *shrink,
320 struct shrink_control *sc)
Jan Karac2f31402016-02-22 12:33:03 -0500321{
Jan Kara7a2508e2016-02-22 22:35:22 -0500322 struct mb_cache *cache = container_of(shrink, struct mb_cache,
Jan Karac2f31402016-02-22 12:33:03 -0500323 c_shrink);
Eric Biggers132d4e22016-12-03 15:43:48 -0500324 return mb_cache_shrink(cache, sc->nr_to_scan);
Jan Karac2f31402016-02-22 12:33:03 -0500325}
326
327/* We shrink 1/X of the cache when we have too many entries in it */
328#define SHRINK_DIVISOR 16
329
Jan Kara7a2508e2016-02-22 22:35:22 -0500330static void mb_cache_shrink_worker(struct work_struct *work)
Jan Karac2f31402016-02-22 12:33:03 -0500331{
Jan Kara7a2508e2016-02-22 22:35:22 -0500332 struct mb_cache *cache = container_of(work, struct mb_cache,
333 c_shrink_work);
334 mb_cache_shrink(cache, cache->c_max_entries / SHRINK_DIVISOR);
Jan Karac2f31402016-02-22 12:33:03 -0500335}
336
Jan Karaf9a61eb2016-02-22 11:49:09 -0500337/*
Jan Kara7a2508e2016-02-22 22:35:22 -0500338 * mb_cache_create - create cache
Jan Karaf9a61eb2016-02-22 11:49:09 -0500339 * @bucket_bits: log2 of the hash table size
340 *
341 * Create cache for keys with 2^bucket_bits hash entries.
342 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500343struct mb_cache *mb_cache_create(int bucket_bits)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500344{
Jan Kara7a2508e2016-02-22 22:35:22 -0500345 struct mb_cache *cache;
Eric Biggers132d4e22016-12-03 15:43:48 -0500346 unsigned long bucket_count = 1UL << bucket_bits;
347 unsigned long i;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500348
Jan Kara7a2508e2016-02-22 22:35:22 -0500349 cache = kzalloc(sizeof(struct mb_cache), GFP_KERNEL);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500350 if (!cache)
351 goto err_out;
352 cache->c_bucket_bits = bucket_bits;
Jan Karac2f31402016-02-22 12:33:03 -0500353 cache->c_max_entries = bucket_count << 4;
Jan Karaf0c8b462016-02-22 18:23:47 -0500354 INIT_LIST_HEAD(&cache->c_list);
355 spin_lock_init(&cache->c_list_lock);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500356 cache->c_hash = kmalloc(bucket_count * sizeof(struct hlist_bl_head),
357 GFP_KERNEL);
358 if (!cache->c_hash) {
359 kfree(cache);
360 goto err_out;
361 }
362 for (i = 0; i < bucket_count; i++)
363 INIT_HLIST_BL_HEAD(&cache->c_hash[i]);
364
Jan Kara7a2508e2016-02-22 22:35:22 -0500365 cache->c_shrink.count_objects = mb_cache_count;
366 cache->c_shrink.scan_objects = mb_cache_scan;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500367 cache->c_shrink.seeks = DEFAULT_SEEKS;
Chao Yu8913f342016-08-31 11:44:36 -0400368 if (register_shrinker(&cache->c_shrink)) {
369 kfree(cache->c_hash);
370 kfree(cache);
371 goto err_out;
372 }
Jan Karaf9a61eb2016-02-22 11:49:09 -0500373
Jan Kara7a2508e2016-02-22 22:35:22 -0500374 INIT_WORK(&cache->c_shrink_work, mb_cache_shrink_worker);
Jan Karac2f31402016-02-22 12:33:03 -0500375
Jan Karaf9a61eb2016-02-22 11:49:09 -0500376 return cache;
377
378err_out:
Jan Karaf9a61eb2016-02-22 11:49:09 -0500379 return NULL;
380}
Jan Kara7a2508e2016-02-22 22:35:22 -0500381EXPORT_SYMBOL(mb_cache_create);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500382
383/*
Jan Kara7a2508e2016-02-22 22:35:22 -0500384 * mb_cache_destroy - destroy cache
Jan Karaf9a61eb2016-02-22 11:49:09 -0500385 * @cache: the cache to destroy
386 *
387 * Free all entries in cache and cache itself. Caller must make sure nobody
388 * (except shrinker) can reach @cache when calling this.
389 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500390void mb_cache_destroy(struct mb_cache *cache)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500391{
Jan Kara7a2508e2016-02-22 22:35:22 -0500392 struct mb_cache_entry *entry, *next;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500393
394 unregister_shrinker(&cache->c_shrink);
395
396 /*
397 * We don't bother with any locking. Cache must not be used at this
398 * point.
399 */
Jan Karaf0c8b462016-02-22 18:23:47 -0500400 list_for_each_entry_safe(entry, next, &cache->c_list, e_list) {
Jan Karaf9a61eb2016-02-22 11:49:09 -0500401 if (!hlist_bl_unhashed(&entry->e_hash_list)) {
402 hlist_bl_del_init(&entry->e_hash_list);
403 atomic_dec(&entry->e_refcnt);
404 } else
405 WARN_ON(1);
Jan Karaf0c8b462016-02-22 18:23:47 -0500406 list_del(&entry->e_list);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500407 WARN_ON(atomic_read(&entry->e_refcnt) != 1);
Jan Kara7a2508e2016-02-22 22:35:22 -0500408 mb_cache_entry_put(cache, entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500409 }
410 kfree(cache->c_hash);
411 kfree(cache);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500412}
Jan Kara7a2508e2016-02-22 22:35:22 -0500413EXPORT_SYMBOL(mb_cache_destroy);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500414
Jan Kara7a2508e2016-02-22 22:35:22 -0500415static int __init mbcache_init(void)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500416{
Jan Kara7a2508e2016-02-22 22:35:22 -0500417 mb_entry_cache = kmem_cache_create("mbcache",
418 sizeof(struct mb_cache_entry), 0,
Jan Karaf9a61eb2016-02-22 11:49:09 -0500419 SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
Eric Biggers21d0f4f2016-12-03 15:28:53 -0500420 if (!mb_entry_cache)
421 return -ENOMEM;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500422 return 0;
423}
424
Jan Kara7a2508e2016-02-22 22:35:22 -0500425static void __exit mbcache_exit(void)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500426{
Jan Kara7a2508e2016-02-22 22:35:22 -0500427 kmem_cache_destroy(mb_entry_cache);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500428}
429
Jan Kara7a2508e2016-02-22 22:35:22 -0500430module_init(mbcache_init)
431module_exit(mbcache_exit)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500432
433MODULE_AUTHOR("Jan Kara <jack@suse.cz>");
434MODULE_DESCRIPTION("Meta block cache (for extended attributes)");
435MODULE_LICENSE("GPL");