[16/19] btrfs: add an api to delete a specific entry from the lru cache

Commit Message

Filipe Manana Jan. 11, 2023, 11:36 a.m. UTC

From: Filipe Manana <[e-mail]>

In order to replace the open coded name cache in send with the lru cache,
we need an API for the lru cache to delete a specific entry for which we
did a previous lookup. This adds the API for it, and a next patch in the
series will use it.

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: use MT_FLAGS_LOCK_EXTERN for the backref cache maple tree
  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 <[e-mail]>
---
 fs/btrfs/lru_cache.c | 16 ++++++++++++----
 fs/btrfs/lru_cache.h |  2 ++
 2 files changed, 14 insertions(+), 4 deletions(-)

Patch

diff --git a/fs/btrfs/lru_cache.c b/fs/btrfs/lru_cache.c
index d85341946213..602801235921 100644
--- a/fs/btrfs/lru_cache.c
+++ b/fs/btrfs/lru_cache.c
@@ -56,8 +56,16 @@  struct btrfs_lru_cache_entry *btrfs_lru_cache_lookup(struct btrfs_lru_cache *cac
 	return entry;
 }
 
-static void delete_entry(struct btrfs_lru_cache *cache,
-			 struct btrfs_lru_cache_entry *entry)
+/*
+ * Remove an entry from the cache.
+ *
+ * @cache:     The cache to remove from.
+ * @entry:     The entry to remove from the cache.
+ *
+ * Note: this also frees the memory used by the entry.
+ */
+void btrfs_lru_cache_remove(struct btrfs_lru_cache *cache,
+			    struct btrfs_lru_cache_entry *entry)
 {
 	struct list_head *prev = entry->list.prev;
 
@@ -126,7 +134,7 @@  int btrfs_lru_cache_store(struct btrfs_lru_cache *cache,
 		lru_entry = list_first_entry(&cache->lru_list,
 					     struct btrfs_lru_cache_entry,
 					     lru_list);
-		delete_entry(cache, lru_entry);
+		btrfs_lru_cache_remove(cache, lru_entry);
 	}
 
 	list_add_tail(&new_entry->lru_list, &cache->lru_list);
@@ -148,7 +156,7 @@  void btrfs_lru_cache_clear(struct btrfs_lru_cache *cache)
 	struct btrfs_lru_cache_entry *tmp;
 
 	list_for_each_entry_safe(entry, tmp, &cache->lru_list, lru_list)
-		delete_entry(cache, entry);
+		btrfs_lru_cache_remove(cache, entry);
 
 	ASSERT(cache->size == 0);
 	ASSERT(mtree_empty(&cache->entries));
diff --git a/fs/btrfs/lru_cache.h b/fs/btrfs/lru_cache.h
index de887d438cfb..57e5bdc57e6d 100644
--- a/fs/btrfs/lru_cache.h
+++ b/fs/btrfs/lru_cache.h
@@ -58,6 +58,8 @@  struct btrfs_lru_cache_entry *btrfs_lru_cache_lookup(struct btrfs_lru_cache *cac
 int btrfs_lru_cache_store(struct btrfs_lru_cache *cache,
 			  struct btrfs_lru_cache_entry *new_entry,
 			  gfp_t gfp);
+void btrfs_lru_cache_remove(struct btrfs_lru_cache *cache,
+			    struct btrfs_lru_cache_entry *entry);
 void btrfs_lru_cache_clear(struct btrfs_lru_cache *cache);
 
 #endif /* BTRFS_LRU_CACHE_H */