[PATCH 2/4][DISCO] shiftfs: rework and extend

[Tyler Hicks]

On 2019-03-27 15:11:26, Christian Brauner wrote:
> /* Mount Options */
> - mark
>   When set the mark mount option indicates that the mount in question is
>   allowed to be shifted. Since shiftfs it mountable in by user namespace root
>   non-initial user namespace this mount options ensures that the system
>   administrator has decided that the marked mount is safe to be shifted.
>   To mark a mount as shiftable CAP_SYS_ADMIN in the user namespace is required.

Just to make sure that I'm understanding the changes that this patch
make to .fill_super... CAP_SYS_ADMIN is still required in the
init_user_ns for that first mark mount, correct?

How does LXD plan to integrate support for shiftfs? Will it be selective
on the mark mounts that it performs on behalf of unprivileged users?

Tyler