diff options
Diffstat (limited to 'fs/btrfs/ref-cache.c')
| -rw-r--r-- | fs/btrfs/ref-cache.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/fs/btrfs/ref-cache.c b/fs/btrfs/ref-cache.c index 30fcb7a..a50ebb6 100644 --- a/fs/btrfs/ref-cache.c +++ b/fs/btrfs/ref-cache.c @@ -21,6 +21,16 @@ #include "ref-cache.h" #include "transaction.h" +/* + * leaf refs are used to cache the information about which extents + * a given leaf has references on. This allows us to process that leaf + * in btrfs_drop_snapshot without needing to read it back from disk. + */ + +/* + * kmalloc a leaf reference struct and update the counters for the + * total ref cache size + */ struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root, int nr_extents) { @@ -40,6 +50,10 @@ struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root, return ref; } +/* + * free a leaf reference struct and update the counters for the + * total ref cache size + */ void btrfs_free_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) { if (!ref) @@ -135,6 +149,10 @@ int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen, return 0; } +/* + * find the leaf ref for a given extent. This returns the ref struct with + * a usage reference incremented + */ struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root, u64 bytenr) { @@ -160,6 +178,10 @@ again: return NULL; } +/* + * add a fully filled in leaf ref struct + * remove all the refs older than a given root generation + */ int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref, int shared) { @@ -184,6 +206,10 @@ int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref, return ret; } +/* + * remove a single leaf ref from the tree. This drops the ref held by the tree + * only + */ int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) { struct btrfs_leaf_ref_tree *tree; |
