linux-kernel - Re: [PATCH] [REGRESSION] ovl: Handle ENOSYS when fileattr support is missing in lower/upper fs

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Message-ID: <CAJfpeguKVzCyUraDQPGw6vdQFfPwTCuZv0JkMxNA69AiRib3kg@mail.gmail.com>
Date:   Tue, 7 Mar 2023 09:38:03 +0100
From:   Miklos Szeredi <miklos@...redi.hu>
To:     jonathan@...m.org
Cc:     Christian Kohlschütter 
        <christian@...lschutter.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        overlayfs <linux-unionfs@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH] [REGRESSION] ovl: Handle ENOSYS when fileattr support is
 missing in lower/upper fs

On Tue, 7 Mar 2023 at 02:12, Jonathan Katz <jkatz@...mlabs.org> wrote:
>
> Hi all,
>
> In pursuing this issue, I downloaded the kernel source to see if I
> could debug it further.  In so doing, it looks like Christian's patch
> was never committed to the main source tree (sorry if my terminology
> is wrong).  This is up to and including the 6.3-rc1.  I could also
> find no mention of the fix in the log.
>
> I am trying to manually apply this patch now, but, I am wondering if
> there was some reason that it was not applied (e.g. it introduces some
> instability?)?

It's fixing the bug in the wrong place, i.e. it's checking for an
-ENOSYS return from vfs_fileattr_get(), but that return value is not
valid at that point.

The right way to fix this bug is to prevent -ENOSYS from being
returned in the first place.

Commit 02c0cab8e734 ("fuse: ioctl: translate ENOSYS") fixes one of
those bugs, but of course it's possible that I missed something in
that fix.

Can you please first verify that an upstream kernel (>v6.0) can also
reproduce this issue?

Thanks,
Miklos



>
> Thank you,
> Jonathan
>
>
>
> On Thu, Feb 23, 2023 at 3:11 PM Jonathan Katz <jkatz@...mlabs.org> wrote:
> >
> > Hi all,
> >
> > Problem persists with me with 6.2.0
> > # mainline --install-latest
> > # reboot
> >
> > # uname -r
> > 6.2.0-060200-generic
> >
> >
> > Representative log messages when mounting:
> > Feb 23 22:50:43 instance-20220314-1510-fileserver-for-overlay kernel:
> > [   44.641683] overlayfs: null uuid detected in lower fs '/', falling
> > back to xino=off,index=off,nfs_export=off.
> >
> >
> >
> > Representative log messages when accessing files:
> > eb 23 23:06:31 instance-20220314-1510-fileserver-for-overlay kernel: [
> >  992.505357] overlayfs: failed to retrieve lower fileattr (8020
> > MeOHH2O RecoverySample2-20221219-A-JJL-WebinarHilic10C-TOF-TT54-Neg-1722.d/Storage.mcf_idx,
> > err=-38)
> > Feb 23 23:06:32 instance-20220314-1510-fileserver-for-overlay kernel:
> > [  993.523712] overlayfs: failed to retrieve lower fileattr (8020
> > MeOHH2O RecoverySample2-20221219-A-JJL-WebinarHilic10C-TOF-TT54-Neg-1722.d/Storage.mcf_idx,
> > err=-38)
> >
> >
> > On Mon, Jan 30, 2023 at 11:27 AM Jonathan Katz <jkatz@...mlabs.org> wrote:
> > >
> > > On Thu, Jan 26, 2023 at 5:26 AM Miklos Szeredi <miklos@...redi.hu> wrote:
> > > >
> > > > On Wed, 18 Jan 2023 at 04:41, Jonathan Katz <jkatz@...mlabs.org> wrote:
> > > >
> > > > > I believe that I am still having issues occur within Ubuntu 22.10 with
> > > > > the 5.19 version of the kernel that might be associated with this
> > > > > discussion.  I apologize up front for any faux pas I make in writing
> > > > > this email.
> > > >
> > > > No need to apologize.   The fix in question went into v6.0 of the
> > > > upstream kernel.  So apparently it's still missing from the distro you
> > > > are using.
> > >
> > > Thank you for the reply! ---  I have upgraded the Kernel and it still
> > > seems to be throwing errors.  Details follow:
> > >
> > > Distro: Ubuntu 22.10.
> > > Upgraded kernel using mainline (mainline --install-latest)
> > >
> > > # uname -a
> > > Linux instance-20220314-1510-fileserver-for-overlay
> > > 6.1.8-060108-generic #202301240742 SMP PREEMPT_DYNAMIC Tue Jan 24
> > > 08:13:53 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
> > >
> > > On mount I still get the following notice in syslog (representative):
> > > Jan 30 19:11:46 instance-20220314-1510-fileserver-for-overlay kernel:
> > > [   71.613334] overlayfs: null uuid detected in lower fs '/', falling
> > > back to xino=off,index=off,nfs_export=off.
> > >
> > > And on access (via samba) I still see the following errors in the
> > > syslog (representative):
> > > Jan 30 19:19:34 instance-20220314-1510-fileserver-for-overlay kernel:
> > > [  539.181858] overlayfs: failed to retrieve lower fileattr (8020
> > > MeOHH2O RecoverySample2-20221219-A-JJL-WebinarHilic10C-TOF-TT54-Neg-1722.d/Storage.mcf_idx,
> > > err=-38)
> > >
> > > And on the Windows client, the software still fails with the same symptomology.
> > >
> > >
> > >
> > >
> > > >
> > > > > An example error from our syslog:
> > > > >
> > > > > kernel: [2702258.538549] overlayfs: failed to retrieve lower fileattr
> > > > > (8020 MeOHH2O
> > > > > RecoverySample2-20221219-A-JJL-WebinarHilic10C-TOF-TT54-Neg-1722.d/analysis.tsf,
> > > > > err=-38)
> > > >
> > > > Yep, looks like the same bug.
> > > >
> > > > Thanks,
> > > > Miklos