Btrfs: don't leak block group on error

In extent-tree.c:btrfs_write_dirty_block_groups(), if the call to
write_one_cache_group() failed, we would return without putting
the block group first.
Signed-off-by: NFilipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

fs/btrfs/extent-tree.c

@@ -3317,10 +3317,9 @@ int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 		last = cache->key.objectid + cache->key.offset;
 
 		err = write_one_cache_group(trans, root, path, cache);
+		btrfs_put_block_group(cache);
 		if (err) /* File system offline */
 			goto out;
-
-		btrfs_put_block_group(cache);
 	}
 
 	while (1) {