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 /* Cache entry flags */
14 enum {
15 MBE_REFERENCED_B = 0,
16 MBE_REUSABLE_B
17 };
18
19 struct mb_cache_entry {
20 /* List of entries in cache - protected by cache->c_list_lock */
21 struct list_head e_list;
22 /*
23 * Hash table list - protected by hash chain bitlock. The entry is
24 * guaranteed to be hashed while e_refcnt > 0.
25 */
26 struct hlist_bl_node e_hash_list;
27 /*
28 * Entry refcount. Once it reaches zero, entry is unhashed and freed.
29 * While refcount > 0, the entry is guaranteed to stay in the hash and
30 * e.g. mb_cache_entry_try_delete() will fail.
31 */
32 atomic_t e_refcnt;
33 /* Key in hash - stable during lifetime of the entry */
34 u32 e_key;
35 unsigned long e_flags;
36 /* User provided value - stable during lifetime of the entry */
37 u64 e_value;
38 };
39
40 struct mb_cache *mb_cache_create(int bucket_bits);
41 void mb_cache_destroy(struct mb_cache *cache);
42
43 int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
44 u64 value, bool reusable);
45 void __mb_cache_entry_free(struct mb_cache *cache,
46 struct mb_cache_entry *entry);
47 void mb_cache_entry_wait_unused(struct mb_cache_entry *entry);
48 static inline void mb_cache_entry_put(struct mb_cache *cache,
49 struct mb_cache_entry *entry)
50 {
51 unsigned int cnt = atomic_dec_return(&entry->e_refcnt);
52
53 if (cnt > 0) {
54 if (cnt <= 2)
55 wake_up_var(&entry->e_refcnt);
56 return;
57 }
58 __mb_cache_entry_free(cache, entry);
59 }
60
61 struct mb_cache_entry *mb_cache_entry_delete_or_get(struct mb_cache *cache,
62 u32 key, u64 value);
63 struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
64 u64 value);
65 struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache,
66 u32 key);
67 struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache,
68 struct mb_cache_entry *entry);
69 void mb_cache_entry_touch(struct mb_cache *cache,
70 struct mb_cache_entry *entry);
71
72 #endif /* _LINUX_MBCACHE_H */
73
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.