1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_MBCACHE_H
3 #define _LINUX_MBCACHE_H
4
5 #include <linux/hash.h>
6 #include <linux/list_bl.h>
7 #include <linux/list.h>
8 #include <linux/atomic.h>
9 #include <linux/fs.h>
10
11 struct mb_cache;
12
13 struct mb_cache_entry {
14 /* List of entries in cache - protected by cache->c_list_lock */
15 struct list_head e_list;
16 /*
17 * Hash table list - protected by hash chain bitlock. The entry is
18 * guaranteed to be hashed while e_refcnt > 0.
19 */
20 struct hlist_bl_node e_hash_list;
21 /*
22 * Entry refcount. Once it reaches zero, entry is unhashed and freed.
23 * While refcount > 0, the entry is guaranteed to stay in the hash and
24 * e.g. mb_cache_entry_try_delete() will fail.
25 */
26 atomic_t e_refcnt;
27 /* Key in hash - stable during lifetime of the entry */
28 u32 e_key;
29 u32 e_referenced:1;
30 u32 e_reusable:1;
31 /* User provided value - stable during lifetime of the entry */
32 u64 e_value;
33 };
34
35 struct mb_cache *mb_cache_create(int bucket_bits);
36 void mb_cache_destroy(struct mb_cache *cache);
37
38 int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
39 u64 value, bool reusable);
40 void __mb_cache_entry_free(struct mb_cache *cache,
41 struct mb_cache_entry *entry);
42 void mb_cache_entry_wait_unused(struct mb_cache_entry *entry);
mb_cache_entry_put(struct mb_cache * cache,struct mb_cache_entry * entry)43 static inline void mb_cache_entry_put(struct mb_cache *cache,
44 struct mb_cache_entry *entry)
45 {
46 unsigned int cnt = atomic_dec_return(&entry->e_refcnt);
47
48 if (cnt > 0) {
49 if (cnt <= 2)
50 wake_up_var(&entry->e_refcnt);
51 return;
52 }
53 __mb_cache_entry_free(cache, entry);
54 }
55
56 struct mb_cache_entry *mb_cache_entry_delete_or_get(struct mb_cache *cache,
57 u32 key, u64 value);
58 struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
59 u64 value);
60 struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache,
61 u32 key);
62 struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache,
63 struct mb_cache_entry *entry);
64 void mb_cache_entry_touch(struct mb_cache *cache,
65 struct mb_cache_entry *entry);
66
67 #endif /* _LINUX_MBCACHE_H */
68
