btrfs: handle btrfs_update_reloc_root failure in commit_fs_roots

btrfs_update_reloc_root will will return errors in the future, so handle
the error properly in commit_fs_roots.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/transaction.c

@@ -1363,7 +1363,9 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
 			spin_unlock(&fs_info->fs_roots_radix_lock);
 
 			btrfs_free_log(trans, root);
-			btrfs_update_reloc_root(trans, root);
+			ret2 = btrfs_update_reloc_root(trans, root);
+			if (ret2)
+				return ret2;
 
 			/* see comments in should_cow_block() */
 			clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);