Btrfs: check the return value of btrfs_start_delalloc_inodes()

We forget to check the return value of btrfs_start_delalloc_inodes(), fix it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

fs/btrfs/dev-replace.c

@@ -465,7 +465,11 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 	 * flush all outstanding I/O and inode extent mappings before the
 	 * copy operation is declared as being finished
 	 */
-	btrfs_start_delalloc_inodes(root, 0);
+	ret = btrfs_start_delalloc_inodes(root, 0);
+	if (ret) {
+		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+		return ret;
+	}
 	btrfs_wait_ordered_extents(root, 0);
 
 	trans = btrfs_start_transaction(root, 0);

fs/btrfs/transaction.c

@@ -1427,7 +1427,9 @@ static int btrfs_flush_all_pending_stuffs(struct btrfs_trans_handle *trans,
 	}
 
 	if (flush_on_commit || snap_pending) {
-		btrfs_start_delalloc_inodes(root, 1);
+		ret = btrfs_start_delalloc_inodes(root, 1);
+		if (ret)
+			return ret;
 		btrfs_wait_ordered_extents(root, 1);
 	}