Re: [PATCH 5/5] generic/733: disable for btrfs

[David Sterba <dsterba@suse.cz>]

On Tue, Mar 19, 2024 at 02:01:00PM -0700, Christoph Hellwig wrote:
> On Tue, Mar 19, 2024 at 07:12:10PM +0100, David Sterba wrote:
> > This tests if a clone source can be read but in btrfs there's an
> > exclusive lock and the test always fails. The functionality might be
> > implemented in btrfs in the future but for now disable the test.
> 
> Well, this sounds like btrf sis broken and it should fail?

It does not sound like that to me, rather that the test was tailored
for xfs and assumes too much about the behaviour that does not apply to
btrfs. If you look at src/t_reflink_read_race.c it's full of magic
constants used for timing, this itself points to an unreliable test
depending on hardware and other system load.

> 
> >  # real QA test starts here
> > -_supported_fs generic
> > +_supported_fs ^btrfs
> 
> 
> and just throwing random not supported in generic testes is just a mine
> field.  You;d better explain very well why something is not supported,
> and do that by adding a _require_.  If you can't explain the
> _require this probably actually is a bug and not just an exclude..

It is a bug in the test, it should have been xfs specific and never
promoted to generic/ and not affect btrfs unless explained how
in the first place.