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From: Miklos Szeredi <miklos@szeredi.hu>
Date: Tue, 28 May 2024 13:34:39 +0200
Message-ID: <CAJfpegu+z2Nxvk2H9vfZ3nfzEEixUG4kEthVGHWUYw0wX5bgMg@mail.gmail.com>
Subject: Re: [PATCH] ovl: change error message to info for empty lowerdir
To: Eric Curtin <ecurtin@redhat.com>
Cc: "open list:OVERLAY FILESYSTEM" <linux-unionfs@vger.kernel.org>, Alexander Larsson <alexl@redhat.com>, 
	Wei Wang <weiwang@redhat.com>, Amir Goldstein <amir73il@gmail.com>, 
	open list <linux-kernel@vger.kernel.org>
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On Tue, 28 May 2024 at 12:55, Eric Curtin <ecurtin@redhat.com> wrote:
>
> On Tue, 28 May 2024 at 11:34, Miklos Szeredi <miklos@szeredi.hu> wrote:
> >
> > On Tue, 28 May 2024 at 11:03, Eric Curtin <ecurtin@redhat.com> wrote:
> > >
> > > In some deployments, an empty lowerdir is not considered an error.
> >
> > I don't think this can be triggered in upstream kernel and can be
> > removed completely.
>
> True... Just switched to Fedora Rawhide and instead we just see this one:
>
> pr_err("cannot append lower layer");
>
> >
> > Or do you have a reproducer?
>
> Run one of these vms:
>
> https://github.com/osbuild/bootc-image-builder

Apparently it is using the legacy lowerdir append mode
"lowerdir=:foo".  This works only on 6.5.

In 6.6 and later the same can be achieved with "lowerdir+=foo".

It's strange that there are not side effects other then the error message.

Thanks,
Miklos