include/linux/mbcache.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef _LINUX_MBCACHE_H
0003 #define _LINUX_MBCACHE_H
0004
0005 #include <linux/hash.h>
0006 #include <linux/list_bl.h>
0007 #include <linux/list.h>
0008 #include <linux/atomic.h>
0009 #include <linux/fs.h>
0010
0011 struct mb_cache;
0012
0013 struct mb_cache_entry {
0014     /* List of entries in cache - protected by cache->c_list_lock */
0015     struct list_head    e_list;
0016     /*
0017      * Hash table list - protected by hash chain bitlock. The entry is
0018      * guaranteed to be hashed while e_refcnt > 0.
0019      */
0020     struct hlist_bl_node    e_hash_list;
0021     /*
0022      * Entry refcount. Once it reaches zero, entry is unhashed and freed.
0023      * While refcount > 0, the entry is guaranteed to stay in the hash and
0024      * e.g. mb_cache_entry_try_delete() will fail.
0025      */
0026     atomic_t        e_refcnt;
0027     /* Key in hash - stable during lifetime of the entry */
0028     u32         e_key;
0029     u32         e_referenced:1;
0030     u32         e_reusable:1;
0031     /* User provided value - stable during lifetime of the entry */
0032     u64         e_value;
0033 };
0034
0035 struct mb_cache *mb_cache_create(int bucket_bits);
0036 void mb_cache_destroy(struct mb_cache *cache);
0037
0038 int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
0039               u64 value, bool reusable);
0040 void __mb_cache_entry_free(struct mb_cache *cache,
0041                struct mb_cache_entry *entry);
0042 void mb_cache_entry_wait_unused(struct mb_cache_entry *entry);
0043 static inline void mb_cache_entry_put(struct mb_cache *cache,
0044                       struct mb_cache_entry *entry)
0045 {
0046     unsigned int cnt = atomic_dec_return(&entry->e_refcnt);
0047
0048     if (cnt > 0) {
0049         if (cnt <= 2)
0050             wake_up_var(&entry->e_refcnt);
0051         return;
0052     }
0053     __mb_cache_entry_free(cache, entry);
0054 }
0055
0056 struct mb_cache_entry *mb_cache_entry_delete_or_get(struct mb_cache *cache,
0057                             u32 key, u64 value);
0058 struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
0059                       u64 value);
0060 struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache,
0061                          u32 key);
0062 struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache,
0063                         struct mb_cache_entry *entry);
0064 void mb_cache_entry_touch(struct mb_cache *cache,
0065               struct mb_cache_entry *entry);
0066
0067 #endif  /* _LINUX_MBCACHE_H */