[CRIU] [PATCH] mount: rework perparation for pivot_root

[Tycho Andersen]

Hi Pavel,

On Wed, Sep 03, 2014 at 08:43:13PM +0400, Pavel Emelyanov wrote:
> On 08/08/2014 04:18 PM, Andrey Vagin wrote:
> > We can't bind-mount the required root into itself instead of
> > resolving a parent mount.
> > 
> > This patch is required to support userns, because if we want to make
> > pivot_root, the parent mount can't be locked. When we create userns
> > and mntns, all inherited mounts are marked as locked.
> > 
> > Cc: Tycho Andersen <tycho.andersen at canonical.com>
> > Signed-off-by: Andrey Vagin <avagin at openvz.org>
> 
> Andrey, Tycho,
> 
> AFAIU we haven't yet decided what to do with the root mountpoint
> preparation. Am I right? Can we resurrect the discussion if it's
> still relevant?

The issue that caused this patch was actually my misunderstanding,
Andrew and I talked about it on IRC. I'm not sure (other than applying
this patch, which is a usability improvement at least) that criu can
do anything to prepare the rootfs. In the case of LXC it could be a
block device or something, which I guess criu doesn't know how to set
up?

Anyway, I think it is ok to expect users to set up their own rootfs,
unless there is some nice way we could do it.

Tycho

> Thanks,
> Pavel
>