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The backref cache is a cache backed by a maple tree and a linked list to keep track of temporal access to cached entries (the LRU entry always at the head of the list). This type of caching method is going to be useful in other scenarios, so make the cache implementation more generic and move it into its own header and source files. This patch is part of a larger patchset and the changelog of the last patch in the series contains a sample performance test and results. The patches that comprise the patchset are the following: btrfs: send: directly return from did_overwrite_ref() and simplify it btrfs: send: avoid unnecessary generation search at did_overwrite_ref() btrfs: send: directly return from will_overwrite_ref() and simplify it btrfs: send: avoid extra b+tree searches when checking reference overrides btrfs: send: remove send_progress argument from can_rmdir() btrfs: send: avoid duplicated orphan dir allocation and initialization btrfs: send: avoid unnecessary orphan dir rbtree search at can_rmdir() btrfs: send: reduce searches on parent root when checking if dir can be removed btrfs: send: iterate waiting dir move rbtree only once when processing refs btrfs: send: initialize all the red black trees earlier btrfs: send: genericize the backref cache to allow it to be reused btrfs: adapt lru cache to allow for 64 bits keys on 32 bits systems btrfs: send: cache information about created directories btrfs: allow a generation number to be associated with lru cache entries btrfs: add an api to delete a specific entry from the lru cache btrfs: send: use the lru cache to implement the name cache btrfs: send: update size of roots array for backref cache entries btrfs: send: cache utimes operations for directories if possible Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
45 lines
1.3 KiB
C
45 lines
1.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef BTRFS_LRU_CACHE_H
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#define BTRFS_LRU_CACHE_H
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#include <linux/maple_tree.h>
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#include <linux/list.h>
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/*
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* A cache entry. This is meant to be embedded in a structure of a user of
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* this module. Similar to how struct list_head and struct rb_node are used.
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*
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* Note: it should be embedded as the first element in a struct (offset 0), and
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* this module assumes it was allocated with kmalloc(), so it calls kfree() when
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* it needs to free an entry.
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*/
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struct btrfs_lru_cache_entry {
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struct list_head lru_list;
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u64 key;
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};
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struct btrfs_lru_cache {
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struct list_head lru_list;
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struct maple_tree entries;
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/* Number of entries stored in the cache. */
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unsigned int size;
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/* Maximum number of entries the cache can have. */
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unsigned int max_size;
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};
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static inline unsigned int btrfs_lru_cache_size(const struct btrfs_lru_cache *cache)
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{
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return cache->size;
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}
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void btrfs_lru_cache_init(struct btrfs_lru_cache *cache, unsigned int max_size);
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struct btrfs_lru_cache_entry *btrfs_lru_cache_lookup(struct btrfs_lru_cache *cache,
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u64 key);
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int btrfs_lru_cache_store(struct btrfs_lru_cache *cache,
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struct btrfs_lru_cache_entry *new_entry,
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gfp_t gfp);
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void btrfs_lru_cache_clear(struct btrfs_lru_cache *cache);
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#endif
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