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90b90d4ac0
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>
98 lines
2.1 KiB
C
98 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/mm.h>
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#include "lru_cache.h"
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#include "messages.h"
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/*
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* Initialize a cache object.
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*
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* @cache: The cache.
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* @max_size: Maximum size (number of entries) for the cache.
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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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{
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INIT_LIST_HEAD(&cache->lru_list);
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mt_init(&cache->entries);
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cache->size = 0;
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cache->max_size = max_size;
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}
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/*
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* Lookup for an entry in the cache.
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*
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* @cache: The cache.
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* @key: The key of the entry we are looking for.
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*
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* Returns the entry associated with the key or NULL if none found.
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*/
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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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{
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struct btrfs_lru_cache_entry *entry;
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entry = mtree_load(&cache->entries, key);
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if (entry)
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list_move_tail(&entry->lru_list, &cache->lru_list);
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return entry;
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}
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/*
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* Store an entry in the cache.
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*
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* @cache: The cache.
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* @entry: The entry to store.
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*
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* Returns 0 on success and < 0 on error.
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*/
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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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{
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int ret;
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if (cache->size == cache->max_size) {
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struct btrfs_lru_cache_entry *lru_entry;
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struct btrfs_lru_cache_entry *mt_entry;
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lru_entry = list_first_entry(&cache->lru_list,
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struct btrfs_lru_cache_entry,
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lru_list);
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mt_entry = mtree_erase(&cache->entries, lru_entry->key);
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ASSERT(mt_entry == lru_entry);
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list_del(&mt_entry->lru_list);
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kfree(mt_entry);
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cache->size--;
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}
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ret = mtree_insert(&cache->entries, new_entry->key, new_entry, gfp);
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if (ret < 0)
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return ret;
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list_add_tail(&new_entry->lru_list, &cache->lru_list);
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cache->size++;
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return 0;
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}
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/*
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* Empty a cache.
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*
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* @cache: The cache to empty.
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*
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* Removes all entries from the cache.
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*/
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void btrfs_lru_cache_clear(struct btrfs_lru_cache *cache)
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{
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struct btrfs_lru_cache_entry *entry;
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struct btrfs_lru_cache_entry *tmp;
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list_for_each_entry_safe(entry, tmp, &cache->lru_list, lru_list)
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kfree(entry);
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INIT_LIST_HEAD(&cache->lru_list);
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mtree_destroy(&cache->entries);
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cache->size = 0;
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}
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