Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 1 | #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 Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 7 | #include <linux/workqueue.h> |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 8 | #include <linux/mbcache.h> |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 9 | |
| 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 Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 13 | * mb_cache_entry_delete_block()). |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 14 | * |
| 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 Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 26 | struct mb_cache { |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 27 | /* Hash table of entries */ |
| 28 | struct hlist_bl_head *c_hash; |
| 29 | /* log2 of hash table size */ |
| 30 | int c_bucket_bits; |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 31 | /* Maximum entries in cache to avoid degrading hash too much */ |
| 32 | int c_max_entries; |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 33 | /* Protects c_list, c_entry_count */ |
| 34 | spinlock_t c_list_lock; |
| 35 | struct list_head c_list; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 36 | /* Number of entries in cache */ |
| 37 | unsigned long c_entry_count; |
| 38 | struct shrinker c_shrink; |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 39 | /* Work for shrinking when the cache has too many entries */ |
| 40 | struct work_struct c_shrink_work; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 41 | }; |
| 42 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 43 | static struct kmem_cache *mb_entry_cache; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 44 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 45 | static unsigned long mb_cache_shrink(struct mb_cache *cache, |
| 46 | unsigned int nr_to_scan); |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 47 | |
Andreas Gruenbacher | dc8d5e5 | 2016-02-22 22:42:05 -0500 | [diff] [blame] | 48 | static inline struct hlist_bl_head *mb_cache_entry_head(struct mb_cache *cache, |
| 49 | u32 key) |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 50 | { |
Andreas Gruenbacher | dc8d5e5 | 2016-02-22 22:42:05 -0500 | [diff] [blame] | 51 | return &cache->c_hash[hash_32(key, cache->c_bucket_bits)]; |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 52 | } |
| 53 | |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 54 | /* |
| 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 Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 60 | /* |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 61 | * mb_cache_entry_create - create entry in cache |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 62 | * @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 |
| 66 | * |
| 67 | * Creates entry in @cache with key @key and records that data is stored in |
| 68 | * block @block. The function returns -EBUSY if entry with the same key |
| 69 | * and for the same block already exists in cache. Otherwise 0 is returned. |
| 70 | */ |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 71 | int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key, |
| 72 | sector_t block) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 73 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 74 | struct mb_cache_entry *entry, *dup; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 75 | struct hlist_bl_node *dup_node; |
| 76 | struct hlist_bl_head *head; |
| 77 | |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 78 | /* Schedule background reclaim if there are too many entries */ |
| 79 | if (cache->c_entry_count >= cache->c_max_entries) |
| 80 | schedule_work(&cache->c_shrink_work); |
| 81 | /* Do some sync reclaim if background reclaim cannot keep up */ |
| 82 | if (cache->c_entry_count >= 2*cache->c_max_entries) |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 83 | mb_cache_shrink(cache, SYNC_SHRINK_BATCH); |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 84 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 85 | entry = kmem_cache_alloc(mb_entry_cache, mask); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 86 | if (!entry) |
| 87 | return -ENOMEM; |
| 88 | |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 89 | INIT_LIST_HEAD(&entry->e_list); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 90 | /* One ref for hash, one ref returned */ |
| 91 | atomic_set(&entry->e_refcnt, 1); |
| 92 | entry->e_key = key; |
| 93 | entry->e_block = block; |
Andreas Gruenbacher | dc8d5e5 | 2016-02-22 22:42:05 -0500 | [diff] [blame] | 94 | head = mb_cache_entry_head(cache, key); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 95 | hlist_bl_lock(head); |
| 96 | hlist_bl_for_each_entry(dup, dup_node, head, e_hash_list) { |
| 97 | if (dup->e_key == key && dup->e_block == block) { |
| 98 | hlist_bl_unlock(head); |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 99 | kmem_cache_free(mb_entry_cache, entry); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 100 | return -EBUSY; |
| 101 | } |
| 102 | } |
| 103 | hlist_bl_add_head(&entry->e_hash_list, head); |
| 104 | hlist_bl_unlock(head); |
| 105 | |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 106 | spin_lock(&cache->c_list_lock); |
| 107 | list_add_tail(&entry->e_list, &cache->c_list); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 108 | /* Grab ref for LRU list */ |
| 109 | atomic_inc(&entry->e_refcnt); |
| 110 | cache->c_entry_count++; |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 111 | spin_unlock(&cache->c_list_lock); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 112 | |
| 113 | return 0; |
| 114 | } |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 115 | EXPORT_SYMBOL(mb_cache_entry_create); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 116 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 117 | void __mb_cache_entry_free(struct mb_cache_entry *entry) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 118 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 119 | kmem_cache_free(mb_entry_cache, entry); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 120 | } |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 121 | EXPORT_SYMBOL(__mb_cache_entry_free); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 122 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 123 | static struct mb_cache_entry *__entry_find(struct mb_cache *cache, |
| 124 | struct mb_cache_entry *entry, |
| 125 | u32 key) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 126 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 127 | struct mb_cache_entry *old_entry = entry; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 128 | struct hlist_bl_node *node; |
| 129 | struct hlist_bl_head *head; |
| 130 | |
Andreas Gruenbacher | dc8d5e5 | 2016-02-22 22:42:05 -0500 | [diff] [blame] | 131 | head = mb_cache_entry_head(cache, key); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 132 | hlist_bl_lock(head); |
| 133 | if (entry && !hlist_bl_unhashed(&entry->e_hash_list)) |
| 134 | node = entry->e_hash_list.next; |
| 135 | else |
| 136 | node = hlist_bl_first(head); |
| 137 | while (node) { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 138 | entry = hlist_bl_entry(node, struct mb_cache_entry, |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 139 | e_hash_list); |
| 140 | if (entry->e_key == key) { |
| 141 | atomic_inc(&entry->e_refcnt); |
| 142 | goto out; |
| 143 | } |
| 144 | node = node->next; |
| 145 | } |
| 146 | entry = NULL; |
| 147 | out: |
| 148 | hlist_bl_unlock(head); |
| 149 | if (old_entry) |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 150 | mb_cache_entry_put(cache, old_entry); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 151 | |
| 152 | return entry; |
| 153 | } |
| 154 | |
| 155 | /* |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 156 | * mb_cache_entry_find_first - find the first entry in cache with given key |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 157 | * @cache: cache where we should search |
| 158 | * @key: key to look for |
| 159 | * |
| 160 | * Search in @cache for entry with key @key. Grabs reference to the first |
| 161 | * entry found and returns the entry. |
| 162 | */ |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 163 | struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache, |
| 164 | u32 key) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 165 | { |
| 166 | return __entry_find(cache, NULL, key); |
| 167 | } |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 168 | EXPORT_SYMBOL(mb_cache_entry_find_first); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 169 | |
| 170 | /* |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 171 | * mb_cache_entry_find_next - find next entry in cache with the same |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 172 | * @cache: cache where we should search |
| 173 | * @entry: entry to start search from |
| 174 | * |
| 175 | * Finds next entry in the hash chain which has the same key as @entry. |
| 176 | * If @entry is unhashed (which can happen when deletion of entry races |
| 177 | * with the search), finds the first entry in the hash chain. The function |
| 178 | * drops reference to @entry and returns with a reference to the found entry. |
| 179 | */ |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 180 | struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache, |
| 181 | struct mb_cache_entry *entry) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 182 | { |
| 183 | return __entry_find(cache, entry, entry->e_key); |
| 184 | } |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 185 | EXPORT_SYMBOL(mb_cache_entry_find_next); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 186 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 187 | /* mb_cache_entry_delete_block - remove information about block from cache |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 188 | * @cache - cache we work with |
| 189 | * @key - key of the entry to remove |
| 190 | * @block - block containing data for @key |
| 191 | * |
| 192 | * Remove entry from cache @cache with key @key with data stored in @block. |
| 193 | */ |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 194 | void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key, |
| 195 | sector_t block) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 196 | { |
| 197 | struct hlist_bl_node *node; |
| 198 | struct hlist_bl_head *head; |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 199 | struct mb_cache_entry *entry; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 200 | |
Andreas Gruenbacher | dc8d5e5 | 2016-02-22 22:42:05 -0500 | [diff] [blame] | 201 | head = mb_cache_entry_head(cache, key); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 202 | hlist_bl_lock(head); |
| 203 | hlist_bl_for_each_entry(entry, node, head, e_hash_list) { |
| 204 | if (entry->e_key == key && entry->e_block == block) { |
| 205 | /* We keep hash list reference to keep entry alive */ |
| 206 | hlist_bl_del_init(&entry->e_hash_list); |
| 207 | hlist_bl_unlock(head); |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 208 | spin_lock(&cache->c_list_lock); |
| 209 | if (!list_empty(&entry->e_list)) { |
| 210 | list_del_init(&entry->e_list); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 211 | cache->c_entry_count--; |
| 212 | atomic_dec(&entry->e_refcnt); |
| 213 | } |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 214 | spin_unlock(&cache->c_list_lock); |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 215 | mb_cache_entry_put(cache, entry); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 216 | return; |
| 217 | } |
| 218 | } |
| 219 | hlist_bl_unlock(head); |
| 220 | } |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 221 | EXPORT_SYMBOL(mb_cache_entry_delete_block); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 222 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 223 | /* mb_cache_entry_touch - cache entry got used |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 224 | * @cache - cache the entry belongs to |
| 225 | * @entry - entry that got used |
| 226 | * |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 227 | * Marks entry as used to give hit higher chances of surviving in cache. |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 228 | */ |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 229 | void mb_cache_entry_touch(struct mb_cache *cache, |
| 230 | struct mb_cache_entry *entry) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 231 | { |
Andreas Gruenbacher | dc8d5e5 | 2016-02-22 22:42:05 -0500 | [diff] [blame] | 232 | entry->e_referenced = 1; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 233 | } |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 234 | EXPORT_SYMBOL(mb_cache_entry_touch); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 235 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 236 | static unsigned long mb_cache_count(struct shrinker *shrink, |
| 237 | struct shrink_control *sc) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 238 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 239 | struct mb_cache *cache = container_of(shrink, struct mb_cache, |
| 240 | c_shrink); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 241 | |
| 242 | return cache->c_entry_count; |
| 243 | } |
| 244 | |
| 245 | /* Shrink number of entries in cache */ |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 246 | static unsigned long mb_cache_shrink(struct mb_cache *cache, |
| 247 | unsigned int nr_to_scan) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 248 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 249 | struct mb_cache_entry *entry; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 250 | struct hlist_bl_head *head; |
| 251 | unsigned int shrunk = 0; |
| 252 | |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 253 | spin_lock(&cache->c_list_lock); |
| 254 | while (nr_to_scan-- && !list_empty(&cache->c_list)) { |
| 255 | entry = list_first_entry(&cache->c_list, |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 256 | struct mb_cache_entry, e_list); |
Andreas Gruenbacher | dc8d5e5 | 2016-02-22 22:42:05 -0500 | [diff] [blame] | 257 | if (entry->e_referenced) { |
| 258 | entry->e_referenced = 0; |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 259 | list_move_tail(&cache->c_list, &entry->e_list); |
| 260 | continue; |
| 261 | } |
| 262 | list_del_init(&entry->e_list); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 263 | cache->c_entry_count--; |
| 264 | /* |
| 265 | * We keep LRU list reference so that entry doesn't go away |
| 266 | * from under us. |
| 267 | */ |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 268 | spin_unlock(&cache->c_list_lock); |
Andreas Gruenbacher | dc8d5e5 | 2016-02-22 22:42:05 -0500 | [diff] [blame] | 269 | head = mb_cache_entry_head(cache, entry->e_key); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 270 | hlist_bl_lock(head); |
| 271 | if (!hlist_bl_unhashed(&entry->e_hash_list)) { |
| 272 | hlist_bl_del_init(&entry->e_hash_list); |
| 273 | atomic_dec(&entry->e_refcnt); |
| 274 | } |
| 275 | hlist_bl_unlock(head); |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 276 | if (mb_cache_entry_put(cache, entry)) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 277 | shrunk++; |
| 278 | cond_resched(); |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 279 | spin_lock(&cache->c_list_lock); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 280 | } |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 281 | spin_unlock(&cache->c_list_lock); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 282 | |
| 283 | return shrunk; |
| 284 | } |
| 285 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 286 | static unsigned long mb_cache_scan(struct shrinker *shrink, |
| 287 | struct shrink_control *sc) |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 288 | { |
| 289 | int nr_to_scan = sc->nr_to_scan; |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 290 | struct mb_cache *cache = container_of(shrink, struct mb_cache, |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 291 | c_shrink); |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 292 | return mb_cache_shrink(cache, nr_to_scan); |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 293 | } |
| 294 | |
| 295 | /* We shrink 1/X of the cache when we have too many entries in it */ |
| 296 | #define SHRINK_DIVISOR 16 |
| 297 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 298 | static void mb_cache_shrink_worker(struct work_struct *work) |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 299 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 300 | struct mb_cache *cache = container_of(work, struct mb_cache, |
| 301 | c_shrink_work); |
| 302 | mb_cache_shrink(cache, cache->c_max_entries / SHRINK_DIVISOR); |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 303 | } |
| 304 | |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 305 | /* |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 306 | * mb_cache_create - create cache |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 307 | * @bucket_bits: log2 of the hash table size |
| 308 | * |
| 309 | * Create cache for keys with 2^bucket_bits hash entries. |
| 310 | */ |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 311 | struct mb_cache *mb_cache_create(int bucket_bits) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 312 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 313 | struct mb_cache *cache; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 314 | int bucket_count = 1 << bucket_bits; |
| 315 | int i; |
| 316 | |
| 317 | if (!try_module_get(THIS_MODULE)) |
| 318 | return NULL; |
| 319 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 320 | cache = kzalloc(sizeof(struct mb_cache), GFP_KERNEL); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 321 | if (!cache) |
| 322 | goto err_out; |
| 323 | cache->c_bucket_bits = bucket_bits; |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 324 | cache->c_max_entries = bucket_count << 4; |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 325 | INIT_LIST_HEAD(&cache->c_list); |
| 326 | spin_lock_init(&cache->c_list_lock); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 327 | cache->c_hash = kmalloc(bucket_count * sizeof(struct hlist_bl_head), |
| 328 | GFP_KERNEL); |
| 329 | if (!cache->c_hash) { |
| 330 | kfree(cache); |
| 331 | goto err_out; |
| 332 | } |
| 333 | for (i = 0; i < bucket_count; i++) |
| 334 | INIT_HLIST_BL_HEAD(&cache->c_hash[i]); |
| 335 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 336 | cache->c_shrink.count_objects = mb_cache_count; |
| 337 | cache->c_shrink.scan_objects = mb_cache_scan; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 338 | cache->c_shrink.seeks = DEFAULT_SEEKS; |
| 339 | register_shrinker(&cache->c_shrink); |
| 340 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 341 | INIT_WORK(&cache->c_shrink_work, mb_cache_shrink_worker); |
Jan Kara | c2f3140 | 2016-02-22 12:33:03 -0500 | [diff] [blame] | 342 | |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 343 | return cache; |
| 344 | |
| 345 | err_out: |
| 346 | module_put(THIS_MODULE); |
| 347 | return NULL; |
| 348 | } |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 349 | EXPORT_SYMBOL(mb_cache_create); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 350 | |
| 351 | /* |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 352 | * mb_cache_destroy - destroy cache |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 353 | * @cache: the cache to destroy |
| 354 | * |
| 355 | * Free all entries in cache and cache itself. Caller must make sure nobody |
| 356 | * (except shrinker) can reach @cache when calling this. |
| 357 | */ |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 358 | void mb_cache_destroy(struct mb_cache *cache) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 359 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 360 | struct mb_cache_entry *entry, *next; |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 361 | |
| 362 | unregister_shrinker(&cache->c_shrink); |
| 363 | |
| 364 | /* |
| 365 | * We don't bother with any locking. Cache must not be used at this |
| 366 | * point. |
| 367 | */ |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 368 | list_for_each_entry_safe(entry, next, &cache->c_list, e_list) { |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 369 | if (!hlist_bl_unhashed(&entry->e_hash_list)) { |
| 370 | hlist_bl_del_init(&entry->e_hash_list); |
| 371 | atomic_dec(&entry->e_refcnt); |
| 372 | } else |
| 373 | WARN_ON(1); |
Jan Kara | f0c8b46 | 2016-02-22 18:23:47 -0500 | [diff] [blame] | 374 | list_del(&entry->e_list); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 375 | WARN_ON(atomic_read(&entry->e_refcnt) != 1); |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 376 | mb_cache_entry_put(cache, entry); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 377 | } |
| 378 | kfree(cache->c_hash); |
| 379 | kfree(cache); |
| 380 | module_put(THIS_MODULE); |
| 381 | } |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 382 | EXPORT_SYMBOL(mb_cache_destroy); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 383 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 384 | static int __init mbcache_init(void) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 385 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 386 | mb_entry_cache = kmem_cache_create("mbcache", |
| 387 | sizeof(struct mb_cache_entry), 0, |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 388 | SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL); |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 389 | BUG_ON(!mb_entry_cache); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 390 | return 0; |
| 391 | } |
| 392 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 393 | static void __exit mbcache_exit(void) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 394 | { |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 395 | kmem_cache_destroy(mb_entry_cache); |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 396 | } |
| 397 | |
Jan Kara | 7a2508e | 2016-02-22 22:35:22 -0500 | [diff] [blame] | 398 | module_init(mbcache_init) |
| 399 | module_exit(mbcache_exit) |
Jan Kara | f9a61eb | 2016-02-22 11:49:09 -0500 | [diff] [blame] | 400 | |
| 401 | MODULE_AUTHOR("Jan Kara <jack@suse.cz>"); |
| 402 | MODULE_DESCRIPTION("Meta block cache (for extended attributes)"); |
| 403 | MODULE_LICENSE("GPL"); |