Re: Should we consider disable generic/563 for file systems that do not support cgroup2?

["Theodore Tso" <tytso@mit.edu>]

On Sun, Jul 19, 2026 at 11:57:04PM -0500, Zorro Lang wrote:
> Thank you for your reply. You are right. I was just listing some
> possible options, and I did not mean we must change the kernel for
> testing. Changing the kernel just for a _notrun is indeed not worth
> it. If there is no simple way to implement the _require_* function,
> we can `_exclude_fs hfs` directly :)

I wouldn't necessarily rule out changing the kernel so that file
systems can declare whether they can support cgroupv2.  The advantage
is that we wouldn't need to keep adding "_exclude_fs xxx" each time we
try to make fstets work on the simpler file systems.  It also means
that if a file system adds support for cgroupv2, we wouldn't need to
change fstests --- also, if the patch gets backported to an older
kernel (either an LTS or an enterprise distro kernel) we don't need to
try to modulate the _exclude_fs using kernel version numbers (which
isn't guaranteed to work given the backporting possibility).

This is a philosophical issue, and reasonable people could disagree on
this approach.  For my part, I created /sys/fs/ext4/features/*
precisely so that userspace (and fstests) so we can test if a
particular feature is available on a particular kernel.  Otherwise, a
test to see whether a particular feature "works" might have a false
positive if the feature is broken, and the way we test whether the
feature is present is basically what was accidentally broken with by a
regression.

Cheers,

					- Ted