blob: b19be429d65592ba2010e0aea0f33fce0a3922d9 [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
Jan Kara7a2508e2016-02-22 22:35:22 -050013 * mb_cache_entry_delete_block()).
Jan Karaf9a61eb2016-02-22 11:49:09 -050014 *
15 * Ext2 and ext4 use this cache for deduplication of extended attribute blocks.
16 * They use hash of a block contents as a key and block number as a value.
17 * That's why keys need not be unique (different xattr blocks may end up having
18 * the same hash). However block number always uniquely identifies a cache
19 * entry.
20 *
21 * We provide functions for creation and removal of entries, search by key,
22 * and a special "delete entry with given key-value pair" operation. Fixed
23 * size hash table is used for fast key lookups.
24 */
25
Jan Kara7a2508e2016-02-22 22:35:22 -050026struct mb_cache {
Jan Karaf9a61eb2016-02-22 11:49:09 -050027 /* Hash table of entries */
28 struct hlist_bl_head *c_hash;
29 /* log2 of hash table size */
30 int c_bucket_bits;
Jan Karac2f31402016-02-22 12:33:03 -050031 /* Maximum entries in cache to avoid degrading hash too much */
Eric Biggers132d4e22016-12-03 15:43:48 -050032 unsigned long c_max_entries;
Jan Karaf0c8b462016-02-22 18:23:47 -050033 /* Protects c_list, c_entry_count */
34 spinlock_t c_list_lock;
35 struct list_head c_list;
Jan Karaf9a61eb2016-02-22 11:49:09 -050036 /* Number of entries in cache */
37 unsigned long c_entry_count;
38 struct shrinker c_shrink;
Jan Karac2f31402016-02-22 12:33:03 -050039 /* Work for shrinking when the cache has too many entries */
40 struct work_struct c_shrink_work;
Jan Karaf9a61eb2016-02-22 11:49:09 -050041};
42
Jan Kara7a2508e2016-02-22 22:35:22 -050043static struct kmem_cache *mb_entry_cache;
Jan Karaf9a61eb2016-02-22 11:49:09 -050044
Jan Kara7a2508e2016-02-22 22:35:22 -050045static unsigned long mb_cache_shrink(struct mb_cache *cache,
Eric Biggers132d4e22016-12-03 15:43:48 -050046 unsigned long nr_to_scan);
Jan Karac2f31402016-02-22 12:33:03 -050047
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -050048static inline struct hlist_bl_head *mb_cache_entry_head(struct mb_cache *cache,
49 u32 key)
Jan Karaf0c8b462016-02-22 18:23:47 -050050{
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -050051 return &cache->c_hash[hash_32(key, cache->c_bucket_bits)];
Jan Karaf0c8b462016-02-22 18:23:47 -050052}
53
Jan Karac2f31402016-02-22 12:33:03 -050054/*
55 * Number of entries to reclaim synchronously when there are too many entries
56 * in cache
57 */
58#define SYNC_SHRINK_BATCH 64
59
Jan Karaf9a61eb2016-02-22 11:49:09 -050060/*
Jan Kara7a2508e2016-02-22 22:35:22 -050061 * mb_cache_entry_create - create entry in cache
Jan Karaf9a61eb2016-02-22 11:49:09 -050062 * @cache - cache where the entry should be created
63 * @mask - gfp mask with which the entry should be allocated
64 * @key - key of the entry
65 * @block - block that contains data
Andreas Gruenbacher6048c642016-02-22 22:44:04 -050066 * @reusable - is the block reusable by other inodes?
Jan Karaf9a61eb2016-02-22 11:49:09 -050067 *
68 * Creates entry in @cache with key @key and records that data is stored in
69 * block @block. The function returns -EBUSY if entry with the same key
70 * and for the same block already exists in cache. Otherwise 0 is returned.
71 */
Jan Kara7a2508e2016-02-22 22:35:22 -050072int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
Andreas Gruenbacher6048c642016-02-22 22:44:04 -050073 sector_t block, bool reusable)
Jan Karaf9a61eb2016-02-22 11:49:09 -050074{
Jan Kara7a2508e2016-02-22 22:35:22 -050075 struct mb_cache_entry *entry, *dup;
Jan Karaf9a61eb2016-02-22 11:49:09 -050076 struct hlist_bl_node *dup_node;
77 struct hlist_bl_head *head;
78
Jan Karac2f31402016-02-22 12:33:03 -050079 /* Schedule background reclaim if there are too many entries */
80 if (cache->c_entry_count >= cache->c_max_entries)
81 schedule_work(&cache->c_shrink_work);
82 /* Do some sync reclaim if background reclaim cannot keep up */
83 if (cache->c_entry_count >= 2*cache->c_max_entries)
Jan Kara7a2508e2016-02-22 22:35:22 -050084 mb_cache_shrink(cache, SYNC_SHRINK_BATCH);
Jan Karac2f31402016-02-22 12:33:03 -050085
Jan Kara7a2508e2016-02-22 22:35:22 -050086 entry = kmem_cache_alloc(mb_entry_cache, mask);
Jan Karaf9a61eb2016-02-22 11:49:09 -050087 if (!entry)
88 return -ENOMEM;
89
Jan Karaf0c8b462016-02-22 18:23:47 -050090 INIT_LIST_HEAD(&entry->e_list);
Jan Karaf9a61eb2016-02-22 11:49:09 -050091 /* One ref for hash, one ref returned */
92 atomic_set(&entry->e_refcnt, 1);
93 entry->e_key = key;
94 entry->e_block = block;
Andreas Gruenbacher6048c642016-02-22 22:44:04 -050095 entry->e_reusable = reusable;
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -050096 head = mb_cache_entry_head(cache, key);
Jan Karaf9a61eb2016-02-22 11:49:09 -050097 hlist_bl_lock(head);
98 hlist_bl_for_each_entry(dup, dup_node, head, e_hash_list) {
99 if (dup->e_key == key && dup->e_block == block) {
100 hlist_bl_unlock(head);
Jan Kara7a2508e2016-02-22 22:35:22 -0500101 kmem_cache_free(mb_entry_cache, entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500102 return -EBUSY;
103 }
104 }
105 hlist_bl_add_head(&entry->e_hash_list, head);
106 hlist_bl_unlock(head);
107
Jan Karaf0c8b462016-02-22 18:23:47 -0500108 spin_lock(&cache->c_list_lock);
109 list_add_tail(&entry->e_list, &cache->c_list);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500110 /* Grab ref for LRU list */
111 atomic_inc(&entry->e_refcnt);
112 cache->c_entry_count++;
Jan Karaf0c8b462016-02-22 18:23:47 -0500113 spin_unlock(&cache->c_list_lock);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500114
115 return 0;
116}
Jan Kara7a2508e2016-02-22 22:35:22 -0500117EXPORT_SYMBOL(mb_cache_entry_create);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500118
Jan Kara7a2508e2016-02-22 22:35:22 -0500119void __mb_cache_entry_free(struct mb_cache_entry *entry)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500120{
Jan Kara7a2508e2016-02-22 22:35:22 -0500121 kmem_cache_free(mb_entry_cache, entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500122}
Jan Kara7a2508e2016-02-22 22:35:22 -0500123EXPORT_SYMBOL(__mb_cache_entry_free);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500124
Jan Kara7a2508e2016-02-22 22:35:22 -0500125static struct mb_cache_entry *__entry_find(struct mb_cache *cache,
126 struct mb_cache_entry *entry,
127 u32 key)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500128{
Jan Kara7a2508e2016-02-22 22:35:22 -0500129 struct mb_cache_entry *old_entry = entry;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500130 struct hlist_bl_node *node;
131 struct hlist_bl_head *head;
132
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500133 head = mb_cache_entry_head(cache, key);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500134 hlist_bl_lock(head);
135 if (entry && !hlist_bl_unhashed(&entry->e_hash_list))
136 node = entry->e_hash_list.next;
137 else
138 node = hlist_bl_first(head);
139 while (node) {
Jan Kara7a2508e2016-02-22 22:35:22 -0500140 entry = hlist_bl_entry(node, struct mb_cache_entry,
Jan Karaf9a61eb2016-02-22 11:49:09 -0500141 e_hash_list);
Andreas Gruenbacher6048c642016-02-22 22:44:04 -0500142 if (entry->e_key == key && entry->e_reusable) {
Jan Karaf9a61eb2016-02-22 11:49:09 -0500143 atomic_inc(&entry->e_refcnt);
144 goto out;
145 }
146 node = node->next;
147 }
148 entry = NULL;
149out:
150 hlist_bl_unlock(head);
151 if (old_entry)
Jan Kara7a2508e2016-02-22 22:35:22 -0500152 mb_cache_entry_put(cache, old_entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500153
154 return entry;
155}
156
157/*
Eric Biggersb6496682016-12-03 15:55:01 -0500158 * mb_cache_entry_find_first - find the first reusable entry with the given key
Jan Karaf9a61eb2016-02-22 11:49:09 -0500159 * @cache: cache where we should search
160 * @key: key to look for
161 *
Eric Biggersb6496682016-12-03 15:55:01 -0500162 * Search in @cache for a reusable entry with key @key. Grabs reference to the
163 * first reusable entry found and returns the entry.
Jan Karaf9a61eb2016-02-22 11:49:09 -0500164 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500165struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache,
166 u32 key)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500167{
168 return __entry_find(cache, NULL, key);
169}
Jan Kara7a2508e2016-02-22 22:35:22 -0500170EXPORT_SYMBOL(mb_cache_entry_find_first);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500171
172/*
Eric Biggersb6496682016-12-03 15:55:01 -0500173 * mb_cache_entry_find_next - find next reusable entry with the same key
Jan Karaf9a61eb2016-02-22 11:49:09 -0500174 * @cache: cache where we should search
175 * @entry: entry to start search from
176 *
Eric Biggersb6496682016-12-03 15:55:01 -0500177 * Finds next reusable entry in the hash chain which has the same key as @entry.
178 * If @entry is unhashed (which can happen when deletion of entry races with the
179 * search), finds the first reusable entry in the hash chain. The function drops
180 * reference to @entry and returns with a reference to the found entry.
Jan Karaf9a61eb2016-02-22 11:49:09 -0500181 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500182struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache,
183 struct mb_cache_entry *entry)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500184{
185 return __entry_find(cache, entry, entry->e_key);
186}
Jan Kara7a2508e2016-02-22 22:35:22 -0500187EXPORT_SYMBOL(mb_cache_entry_find_next);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500188
Andreas Gruenbacher6048c642016-02-22 22:44:04 -0500189/*
190 * mb_cache_entry_get - get a cache entry by block number (and key)
191 * @cache - cache we work with
192 * @key - key of block number @block
193 * @block - block number
194 */
195struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
196 sector_t block)
197{
198 struct hlist_bl_node *node;
199 struct hlist_bl_head *head;
200 struct mb_cache_entry *entry;
201
202 head = mb_cache_entry_head(cache, key);
203 hlist_bl_lock(head);
204 hlist_bl_for_each_entry(entry, node, head, e_hash_list) {
205 if (entry->e_key == key && entry->e_block == block) {
206 atomic_inc(&entry->e_refcnt);
207 goto out;
208 }
209 }
210 entry = NULL;
211out:
212 hlist_bl_unlock(head);
213 return entry;
214}
215EXPORT_SYMBOL(mb_cache_entry_get);
216
Jan Kara7a2508e2016-02-22 22:35:22 -0500217/* mb_cache_entry_delete_block - remove information about block from cache
Jan Karaf9a61eb2016-02-22 11:49:09 -0500218 * @cache - cache we work with
Andreas Gruenbacher6048c642016-02-22 22:44:04 -0500219 * @key - key of block @block
220 * @block - block number
Jan Karaf9a61eb2016-02-22 11:49:09 -0500221 *
222 * Remove entry from cache @cache with key @key with data stored in @block.
223 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500224void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key,
225 sector_t block)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500226{
227 struct hlist_bl_node *node;
228 struct hlist_bl_head *head;
Jan Kara7a2508e2016-02-22 22:35:22 -0500229 struct mb_cache_entry *entry;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500230
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500231 head = mb_cache_entry_head(cache, key);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500232 hlist_bl_lock(head);
233 hlist_bl_for_each_entry(entry, node, head, e_hash_list) {
234 if (entry->e_key == key && entry->e_block == block) {
235 /* We keep hash list reference to keep entry alive */
236 hlist_bl_del_init(&entry->e_hash_list);
237 hlist_bl_unlock(head);
Jan Karaf0c8b462016-02-22 18:23:47 -0500238 spin_lock(&cache->c_list_lock);
239 if (!list_empty(&entry->e_list)) {
240 list_del_init(&entry->e_list);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500241 cache->c_entry_count--;
242 atomic_dec(&entry->e_refcnt);
243 }
Jan Karaf0c8b462016-02-22 18:23:47 -0500244 spin_unlock(&cache->c_list_lock);
Jan Kara7a2508e2016-02-22 22:35:22 -0500245 mb_cache_entry_put(cache, entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500246 return;
247 }
248 }
249 hlist_bl_unlock(head);
250}
Jan Kara7a2508e2016-02-22 22:35:22 -0500251EXPORT_SYMBOL(mb_cache_entry_delete_block);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500252
Jan Kara7a2508e2016-02-22 22:35:22 -0500253/* mb_cache_entry_touch - cache entry got used
Jan Karaf9a61eb2016-02-22 11:49:09 -0500254 * @cache - cache the entry belongs to
255 * @entry - entry that got used
256 *
Jan Karaf0c8b462016-02-22 18:23:47 -0500257 * Marks entry as used to give hit higher chances of surviving in cache.
Jan Karaf9a61eb2016-02-22 11:49:09 -0500258 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500259void mb_cache_entry_touch(struct mb_cache *cache,
260 struct mb_cache_entry *entry)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500261{
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500262 entry->e_referenced = 1;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500263}
Jan Kara7a2508e2016-02-22 22:35:22 -0500264EXPORT_SYMBOL(mb_cache_entry_touch);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500265
Jan Kara7a2508e2016-02-22 22:35:22 -0500266static unsigned long mb_cache_count(struct shrinker *shrink,
267 struct shrink_control *sc)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500268{
Jan Kara7a2508e2016-02-22 22:35:22 -0500269 struct mb_cache *cache = container_of(shrink, struct mb_cache,
270 c_shrink);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500271
272 return cache->c_entry_count;
273}
274
275/* Shrink number of entries in cache */
Jan Kara7a2508e2016-02-22 22:35:22 -0500276static unsigned long mb_cache_shrink(struct mb_cache *cache,
Eric Biggers132d4e22016-12-03 15:43:48 -0500277 unsigned long nr_to_scan)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500278{
Jan Kara7a2508e2016-02-22 22:35:22 -0500279 struct mb_cache_entry *entry;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500280 struct hlist_bl_head *head;
Eric Biggers132d4e22016-12-03 15:43:48 -0500281 unsigned long shrunk = 0;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500282
Jan Karaf0c8b462016-02-22 18:23:47 -0500283 spin_lock(&cache->c_list_lock);
284 while (nr_to_scan-- && !list_empty(&cache->c_list)) {
285 entry = list_first_entry(&cache->c_list,
Jan Kara7a2508e2016-02-22 22:35:22 -0500286 struct mb_cache_entry, e_list);
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500287 if (entry->e_referenced) {
288 entry->e_referenced = 0;
Eric Biggers918b7302016-12-03 15:13:15 -0500289 list_move_tail(&entry->e_list, &cache->c_list);
Jan Karaf0c8b462016-02-22 18:23:47 -0500290 continue;
291 }
292 list_del_init(&entry->e_list);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500293 cache->c_entry_count--;
294 /*
295 * We keep LRU list reference so that entry doesn't go away
296 * from under us.
297 */
Jan Karaf0c8b462016-02-22 18:23:47 -0500298 spin_unlock(&cache->c_list_lock);
Andreas Gruenbacherdc8d5e52016-02-22 22:42:05 -0500299 head = mb_cache_entry_head(cache, entry->e_key);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500300 hlist_bl_lock(head);
301 if (!hlist_bl_unhashed(&entry->e_hash_list)) {
302 hlist_bl_del_init(&entry->e_hash_list);
303 atomic_dec(&entry->e_refcnt);
304 }
305 hlist_bl_unlock(head);
Jan Kara7a2508e2016-02-22 22:35:22 -0500306 if (mb_cache_entry_put(cache, entry))
Jan Karaf9a61eb2016-02-22 11:49:09 -0500307 shrunk++;
308 cond_resched();
Jan Karaf0c8b462016-02-22 18:23:47 -0500309 spin_lock(&cache->c_list_lock);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500310 }
Jan Karaf0c8b462016-02-22 18:23:47 -0500311 spin_unlock(&cache->c_list_lock);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500312
313 return shrunk;
314}
315
Jan Kara7a2508e2016-02-22 22:35:22 -0500316static unsigned long mb_cache_scan(struct shrinker *shrink,
317 struct shrink_control *sc)
Jan Karac2f31402016-02-22 12:33:03 -0500318{
Jan Kara7a2508e2016-02-22 22:35:22 -0500319 struct mb_cache *cache = container_of(shrink, struct mb_cache,
Jan Karac2f31402016-02-22 12:33:03 -0500320 c_shrink);
Eric Biggers132d4e22016-12-03 15:43:48 -0500321 return mb_cache_shrink(cache, sc->nr_to_scan);
Jan Karac2f31402016-02-22 12:33:03 -0500322}
323
324/* We shrink 1/X of the cache when we have too many entries in it */
325#define SHRINK_DIVISOR 16
326
Jan Kara7a2508e2016-02-22 22:35:22 -0500327static void mb_cache_shrink_worker(struct work_struct *work)
Jan Karac2f31402016-02-22 12:33:03 -0500328{
Jan Kara7a2508e2016-02-22 22:35:22 -0500329 struct mb_cache *cache = container_of(work, struct mb_cache,
330 c_shrink_work);
331 mb_cache_shrink(cache, cache->c_max_entries / SHRINK_DIVISOR);
Jan Karac2f31402016-02-22 12:33:03 -0500332}
333
Jan Karaf9a61eb2016-02-22 11:49:09 -0500334/*
Jan Kara7a2508e2016-02-22 22:35:22 -0500335 * mb_cache_create - create cache
Jan Karaf9a61eb2016-02-22 11:49:09 -0500336 * @bucket_bits: log2 of the hash table size
337 *
338 * Create cache for keys with 2^bucket_bits hash entries.
339 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500340struct mb_cache *mb_cache_create(int bucket_bits)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500341{
Jan Kara7a2508e2016-02-22 22:35:22 -0500342 struct mb_cache *cache;
Eric Biggers132d4e22016-12-03 15:43:48 -0500343 unsigned long bucket_count = 1UL << bucket_bits;
344 unsigned long i;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500345
Jan Kara7a2508e2016-02-22 22:35:22 -0500346 cache = kzalloc(sizeof(struct mb_cache), GFP_KERNEL);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500347 if (!cache)
348 goto err_out;
349 cache->c_bucket_bits = bucket_bits;
Jan Karac2f31402016-02-22 12:33:03 -0500350 cache->c_max_entries = bucket_count << 4;
Jan Karaf0c8b462016-02-22 18:23:47 -0500351 INIT_LIST_HEAD(&cache->c_list);
352 spin_lock_init(&cache->c_list_lock);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500353 cache->c_hash = kmalloc(bucket_count * sizeof(struct hlist_bl_head),
354 GFP_KERNEL);
355 if (!cache->c_hash) {
356 kfree(cache);
357 goto err_out;
358 }
359 for (i = 0; i < bucket_count; i++)
360 INIT_HLIST_BL_HEAD(&cache->c_hash[i]);
361
Jan Kara7a2508e2016-02-22 22:35:22 -0500362 cache->c_shrink.count_objects = mb_cache_count;
363 cache->c_shrink.scan_objects = mb_cache_scan;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500364 cache->c_shrink.seeks = DEFAULT_SEEKS;
Chao Yu8913f342016-08-31 11:44:36 -0400365 if (register_shrinker(&cache->c_shrink)) {
366 kfree(cache->c_hash);
367 kfree(cache);
368 goto err_out;
369 }
Jan Karaf9a61eb2016-02-22 11:49:09 -0500370
Jan Kara7a2508e2016-02-22 22:35:22 -0500371 INIT_WORK(&cache->c_shrink_work, mb_cache_shrink_worker);
Jan Karac2f31402016-02-22 12:33:03 -0500372
Jan Karaf9a61eb2016-02-22 11:49:09 -0500373 return cache;
374
375err_out:
Jan Karaf9a61eb2016-02-22 11:49:09 -0500376 return NULL;
377}
Jan Kara7a2508e2016-02-22 22:35:22 -0500378EXPORT_SYMBOL(mb_cache_create);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500379
380/*
Jan Kara7a2508e2016-02-22 22:35:22 -0500381 * mb_cache_destroy - destroy cache
Jan Karaf9a61eb2016-02-22 11:49:09 -0500382 * @cache: the cache to destroy
383 *
384 * Free all entries in cache and cache itself. Caller must make sure nobody
385 * (except shrinker) can reach @cache when calling this.
386 */
Jan Kara7a2508e2016-02-22 22:35:22 -0500387void mb_cache_destroy(struct mb_cache *cache)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500388{
Jan Kara7a2508e2016-02-22 22:35:22 -0500389 struct mb_cache_entry *entry, *next;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500390
391 unregister_shrinker(&cache->c_shrink);
392
393 /*
394 * We don't bother with any locking. Cache must not be used at this
395 * point.
396 */
Jan Karaf0c8b462016-02-22 18:23:47 -0500397 list_for_each_entry_safe(entry, next, &cache->c_list, e_list) {
Jan Karaf9a61eb2016-02-22 11:49:09 -0500398 if (!hlist_bl_unhashed(&entry->e_hash_list)) {
399 hlist_bl_del_init(&entry->e_hash_list);
400 atomic_dec(&entry->e_refcnt);
401 } else
402 WARN_ON(1);
Jan Karaf0c8b462016-02-22 18:23:47 -0500403 list_del(&entry->e_list);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500404 WARN_ON(atomic_read(&entry->e_refcnt) != 1);
Jan Kara7a2508e2016-02-22 22:35:22 -0500405 mb_cache_entry_put(cache, entry);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500406 }
407 kfree(cache->c_hash);
408 kfree(cache);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500409}
Jan Kara7a2508e2016-02-22 22:35:22 -0500410EXPORT_SYMBOL(mb_cache_destroy);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500411
Jan Kara7a2508e2016-02-22 22:35:22 -0500412static int __init mbcache_init(void)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500413{
Jan Kara7a2508e2016-02-22 22:35:22 -0500414 mb_entry_cache = kmem_cache_create("mbcache",
415 sizeof(struct mb_cache_entry), 0,
Jan Karaf9a61eb2016-02-22 11:49:09 -0500416 SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
Eric Biggers21d0f4f2016-12-03 15:28:53 -0500417 if (!mb_entry_cache)
418 return -ENOMEM;
Jan Karaf9a61eb2016-02-22 11:49:09 -0500419 return 0;
420}
421
Jan Kara7a2508e2016-02-22 22:35:22 -0500422static void __exit mbcache_exit(void)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500423{
Jan Kara7a2508e2016-02-22 22:35:22 -0500424 kmem_cache_destroy(mb_entry_cache);
Jan Karaf9a61eb2016-02-22 11:49:09 -0500425}
426
Jan Kara7a2508e2016-02-22 22:35:22 -0500427module_init(mbcache_init)
428module_exit(mbcache_exit)
Jan Karaf9a61eb2016-02-22 11:49:09 -0500429
430MODULE_AUTHOR("Jan Kara <jack@suse.cz>");
431MODULE_DESCRIPTION("Meta block cache (for extended attributes)");
432MODULE_LICENSE("GPL");