Re: [PATCH] ovl: relax lookup error on mismatch origin ftype

[Amir Goldstein <amir73il@gmail.com>]

On Wed, Jul 21, 2021 at 4:10 PM Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> On Tue, 27 Apr 2021 at 12:28, Amir Goldstein <amir73il@gmail.com> wrote:
> >
> > We get occasional reports of lookup errors due to mismatched
> > origin ftype from users that re-format a lower squashfs image.
> >
> > Commit 13c6ad0f45fd ("ovl: document lower modification caveats")
> > tries to discourage the practice of re-formating lower layers and
> > describes the expected behavior as undefined.
> >
> > Commit b0e0f69731cd ("ovl: restrict lower null uuid for "xino=auto"")
> > limits the configurations in which origin file handles are followed.
> >
> > In addition to these measures, change the behavior in case of detecting
> > a mismatch origin ftype in lookup to issue a warning, not follow origin,
> > but not fail the lookup operation either.
> >
> > That should make overall more users happy without any big consequences.
> >
> > Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxgPq9E9xxwU2CDyHy-_yCZZeymg+3n+-6AqkGGE1YtwvQ@mail.gmail.com/
> > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > ---
> >
> > Miklos,
> >
> > I am getting tired of dealing with lower squashfs related reports.
> > How about this?
> >
> > It passes the xfstests quick tests and no, I do not have a reproducer
> > for origin mismatch, so will wait for Byron to test the patch.
>
> Pushed a simplified variant that just changes the
> ovl_check_origin_fh() return value from -EIO to -ESTALE.   Do you see
> a problem with this?
>

The only difference is if ovl_fh_to_dentry() also emits a warning,
but since ovl_check_origin_fh() already has a warning I think that
your simplified version is fine.

Thanks,
Amir.