btrfs: return the actual error value from from btrfs_uuid_tree_iterate

In function btrfs_uuid_tree_iterate(), errno is assigned to variable ret
on errors. However, it directly returns 0. It may be better to return
ret. This patch also removes the warning, because the caller already
prints a warning.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188731Signed-off-by: NPan Bian <bianpan2016@163.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
[ edited subject ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/uuid-tree.c

@@ -352,7 +352,5 @@ int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info,
 
 out:
 	btrfs_free_path(path);
-	if (ret)
-		btrfs_warn(fs_info, "btrfs_uuid_tree_iterate failed %d", ret);
-	return 0;
+	return ret;
 }