Btrfs: Find and remove dead roots the first time a root is loaded.

Dead roots are trees left over after a crash, and they were either in the
process of being removed or were waiting to be removed when the box crashed.
Before, a search of the entire tree of root pointers was done on mount
looking for dead roots.  Now, the search is done the first time we load
a root.

This makes mount faster when there are a large number of snapshots, and it
enables the block accounting code to properly update the block counts on
the latest root as old versions of the root are reaped after a crash.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 03e1c4a..6d6e94b 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1148,7 +1148,8 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
                      *item);
 int btrfs_find_last_root(struct btrfs_root *root, u64 objectid, struct
                         btrfs_root_item *item, struct btrfs_key *key);
-int btrfs_find_dead_roots(struct btrfs_root *root);
+int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid,
+                         struct btrfs_root *latest_root);
 /* dir-item.c */
 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
                          *root, const char *name, int name_len, u64 dir,

diff --cc fs/btrfs/disk-io.c
Simple merge

diff --cc fs/btrfs/root-tree.c
Simple merge

diff --cc fs/btrfs/transaction.c
Simple merge

diff --cc fs/btrfs/transaction.h
Simple merge