Re: [PATCH 4/4] ovl: alllow remote upper

From: Vivek Goyal <vgoyal@redhat.com>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
	Miklos Szeredi <mszeredi@redhat.com>,
	overlayfs <linux-unionfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 4/4] ovl: alllow remote upper
Date: Mon, 16 Mar 2020 15:40:17 -0400	[thread overview]
Message-ID: <20200316194017.GC4013@redhat.com> (raw)
In-Reply-To: <CAOQ4uxgfTJwE2O1GGt-TY+6ijjKE13+ATTarijFGLiM69jk8HA@mail.gmail.com>

On Mon, Mar 16, 2020 at 09:02:32PM +0200, Amir Goldstein wrote:
[..]
> > > Could you please make sure that the code in ovl-strict-upper branch
> > > works as expected for virtio as upper fs?
> >
> > Hi Amir,
> >
> > Right now it fails becuase virtiofs doesn't seem to support tmpfile yet.
> >
> > overlayfs: upper fs does not support tmpfile
> > overlayfs: upper fs missing required features.
> >
> > Will have to check what's required to support it.
> >
> > I also wanted to run either overlay xfstests or unionmount-testsuite. But
> > none of these seem to give me enough flexibility where I can specify
> > that overlayfs needs to be mounted on top of virtiofs.
> >
> > I feel that atleast for unionmount-testsuite, there should be an
> > option where we can simply give a target directory and tests run
> > on that directory and user mounts that directory as needed.
> >
> 
> Need to see how patches look.
> Don't want too much configuration complexity, but I agree that some
> flexibly is needed.
> Maybe the provided target directory should be the upper/work basedir?
> 
> > > I have rebased it on latest overlayfs-next merge into current master.
> > >
> > > I would very much prefer that the code merged to v5.7-rc1 will be more
> > > restrictive than the current overlayfs-next.
> >
> > In general I agree that if we want to not support some configuration
> > with remote upper, this is the time to introduce that restriction
> > otherwise we will later run into backward compatibility issue.
> >
> > Having said that, tmpfile support for upper sounds like a nice to
> > have feature. Not sure why to make it mandatory.
> >
> 
> Agreed, I just went automatic on all the warnings.
> tmpfile should not be a requirement for upper.
> Could you please verify that if dropping the tmpfile strict check,
> virtio can be used as upper.

I dropped tmpfile strict check and now I can mount overlayfs using
virtiofs as upper. Tried few basic file operations and these are
working.

Vivek