Btrfs: don't bother autodefragging if our root is going away

We can end up with inodes on the auto defrag list that exist on roots that are
going to be deleted.  This is extra work we don't need to do, so just bail if
our root has 0 root refs.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 8e686a427ce2..8cc941e5b3e1 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -310,6 +310,11 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
                 goto cleanup;
         }
 
+        if (btrfs_root_refs(&inode_root->root_item) == 0) {
+                ret = -ENOENT;
+                goto cleanup;
+        }
+
         key.objectid = defrag->ino;
         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
         key.offset = 0;