Chris Mason f87f057b49 Btrfs: Improve and cleanup locking done by walk_down_tree ... While dropping snapshots, walk_down_tree does most of the work of checking reference counts and limiting tree traversal to just the blocks that we are freeing. It dropped and held the allocation mutex in strange and confusing ways, this commit changes it to only hold the mutex while actually freeing a block. The rest of the checks around reference counts should be safe without the lock because we only allow one process in btrfs_drop_snapshot at a time. Other processes dropping reference counts should not drop it to 1 because their tree roots already have an extra ref on the block. Signed-off-by: Chris Mason <chris.mason@oracle.com>		2008-09-25 11:04:06 -04:00
fs/btrfs	Btrfs: Improve and cleanup locking done by walk_down_tree	2008-09-25 11:04:06 -04:00