Re: [RFC PATCH 2/2] libfs: Improve behavior when directory offset values wrap

[Amir Goldstein <amir73il@gmail.com>]

On Thu, Nov 21, 2024 at 10:30 PM Chuck Lever <chuck.lever@oracle.com> wrote:
>
> On Thu, Nov 21, 2024 at 01:18:05PM -0800, Hugh Dickins wrote:
> > On Thu, 21 Nov 2024, Chuck Lever III wrote:
> > >
> > > I will note that tmpfs hangs during generic/449 for me 100%
> > > of the time; the failure appears unrelated to renames. Do you
> > > know if there is regular CI being done for tmpfs? I'm planning
> > > to add it to my nightly test rig once I'm done here.
> >
> > For me generic/449 did not hang, just took a long time to discover
> > something uninteresting and eventually declare "not run".  Took
> > 14 minutes six years ago, when I gave up on it and short-circuited
> > the "not run" with the patch below.
> >
> > (I carry about twenty patches for my own tmpfs fstests testing; but
> > many of those are just for ancient 32-bit environment, or to suit the
> > "huge=always" option. I never have enough time/priority to review and
> > post them, but can send you a tarball if they might of use to you.)
> >
> > generic/449 is one of those tests which expects metadata to occupy
> > space inside the "disk", in a way which it does not on tmpfs (and a
> > quick glance at its history suggests btrfs also had issues with it).
> >
> > [PATCH] generic/449: not run on tmpfs earlier
> >
> > Do not waste 14 minutes to discover that tmpfs succeeds in
> > setting acls despite running out of space for user attrs.
> >
> > Signed-off-by: Hugh Dickins <hughd@google.com>
> > ---
> >  tests/generic/449 | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/tests/generic/449 b/tests/generic/449
> > index 9cf814ad..a52a992b 100755
> > --- a/tests/generic/449
> > +++ b/tests/generic/449
> > @@ -22,6 +22,11 @@ _require_test
> >  _require_acls
> >  _require_attrs trusted
> >
> > +if [ "$FSTYP" = "tmpfs" ]; then
> > +     # Do not waste 14 minutes to discover this:
> > +     _notrun "$FSTYP succeeds in setting acls despite running out of space for user attrs"
> > +fi
> > +
> >  _scratch_mkfs_sized $((256 * 1024 * 1024)) >> $seqres.full 2>&1
> >  _scratch_mount || _fail "mount failed"
> >
> > --
> > 2.35.3
>
> My approach (until I could look into the failure more) has been
> similar:
>
> diff --git a/tests/generic/449 b/tests/generic/449
> index 9cf814ad326c..8307a43ce87f 100755
> --- a/tests/generic/449
> +++ b/tests/generic/449
> @@ -21,6 +21,7 @@ _require_scratch
>  _require_test
>  _require_acls
>  _require_attrs trusted
> +_supported_fs ^nfs ^overlay ^tmpfs
>

nfs and overlay are _notrun because they do not support _scratch_mkfs_sized

>  _scratch_mkfs_sized $((256 * 1024 * 1024)) >> $seqres.full 2>&1
>  _scratch_mount || _fail "mount failed"
>
>
> I stole it from somewhere else, so it's not tmpfs-specific.

I think opt-out for a certain fs makes sense in some tests, but it is
prefered to describe the requirement that is behind the opt-out.

For example, you thought that nfs,overlay,tmpfs should all opt-out
from this test. Why? Which property do they share in common and
how can it be described in a generic way?

I am not talking about a property that can be checked.
Sometimes we need to make groups of filesystems that share a common
property that cannot be tested, to better express the requirements.

_fstyp_has_non_default_seek_data_hole() is the only example that
comes to mind but there could be others.

Thanks,
Amir.