Let's make sure btrfs_subvol_make() can operate on O_PATH fds, just like mkdirat(). Fixes a bunch of tmpfiles errors at boot if we try to create btrfs subvols, introduced by e54c79ccc2 Fixes: e54c79ccc2
e54c79ccc2
Also make btrfs_subvol_make() an openat style function.