include/linux/mbcache.h

   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 */