Line data    Source code

       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          79 : static inline void mb_cache_entry_put(struct mb_cache *cache,
      49             :                                       struct mb_cache_entry *entry)
      50             : {
      51          79 :         unsigned int cnt = atomic_dec_return(&entry->e_refcnt);
      52             : 
      53          79 :         if (cnt > 0) {
      54          51 :                 if (cnt <= 2)
      55          51 :                         wake_up_var(&entry->e_refcnt);
      56          51 :                 return;
      57             :         }
      58          28 :         __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 */