From: David Sterba <dsterba@suse.com>

commit 6819703f5a365c95488b07066a8744841bf14231 upstream.

The defrag loop processes leaves in batches and starting transaction for
each. The whole defragmentation on a given root is protected by a bit
but in case the transaction fails, the bit is not cleared

In case the transaction fails the bit would prevent starting
defragmentation again, so make sure it's cleared.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Qu Wenruo <redacted>
Reviewed-by: Anand Jain <redacted>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/btrfs/transaction.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c

@@ -1406,8 +1406,10 @@ int btrfs_defrag_root(struct btrfs_root
 
 	while (1) {
 		trans = btrfs_start_transaction(root, 0);
-		if (IS_ERR(trans))
-			return PTR_ERR(trans);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			break;
+		}
 
 		ret = btrfs_defrag_leaves(trans, root);