[CRIU] [PATCH 03/14] mount: rework perparation for pivot_root (v4)

[Pavel Emelyanov]

On 10/16/2014 12:11 AM, 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.
> 
> This patch doesn't change properties of the root mount or any other
> mounts of the restored namespace. It is needed to satisfy pivot_root().
> 
> v2: don't change properties of the given root
> v3: bind-mount root into itself recursevly
> v4: A parent of the new root may be a shared mount. In a previous
> versions a temporary mount is propogated to its neibours.
> 
> Cc: Tycho Andersen <tycho.andersen at canonical.com>
> Signed-off-by: Andrey Vagin <avagin at openvz.org>

Let's better require user to prepare valid root himself (again) and
not do black-magic inside criu. This is _restore_. which means, that
we got this state on dump from somewhere. And this "somewhere" had
the root prepared at _that_ time. So before user calls criu restore
hi knows how to make the root and can (and will) do it again.

Thoughts?

Thanks,
Pavel