linux-kernel - Re: [PATCH 3/3] ovl: redirect on rename-dir

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Message-ID: <20161028125620.uusbhlcwncmicvab@home.ouaza.com>
Date:   Fri, 28 Oct 2016 14:56:20 +0200
From:   Raphael Hertzog <hertzog@...ian.org>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     Miklos Szeredi <mszeredi@...hat.com>,
        "linux-unionfs@...r.kernel.org" <linux-unionfs@...r.kernel.org>,
        Guillem Jover <guillem@...ian.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] ovl: redirect on rename-dir

Hi,

On Wed, 26 Oct 2016, Miklos Szeredi wrote:
> On Tue, Oct 25, 2016 at 1:57 PM, Raphael Hertzog <hertzog@...ian.org> wrote:

[ redirect feature enabled by default ]

> I think it would be safe to make it the default if upperdir is empty.
> Nonempty implies that it was created with old kernel (or it was
> crafted by hand).   But there should be a way to explicitly turn it
> off;  either because of the need for backward compatibility or because
> the old format is simply easier to work with for humans.
> 
> How about:
> 
> - If upper is nonempty, then leave redirect feature alone except when
> mount option "-oredirect=on" is used to force enabling it.
> - If upper is empty, then enable redirect feature except when mount
> option "-oredirect=off" is used to force disabling it.

Looks good, but is there some stickyness of the setting? My use case is
schroot and it always starts with an empty upperdir when I create a
temporary/throw-away chroot but if I reboot the machine, then it's possible
that schroot will remount the overlayfs with a non-empty upperdir
(the temporary chroot is preserved until I explicitly end the chroot).

Cheers,
-- 
Raphaël Hertzog ◈ Debian Developer

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