[CRIU] Sync TODO-s for mount.c work

[Oleg Nesterov]

Hi Tycho,

On 04/21, Tycho Andersen wrote:
>
> On Tue, Apr 21, 2015 at 05:17:33PM +0200, Oleg Nesterov wrote:
> >
> > yes, otherwise (to me) "--ext-mount-map auto" simply doesn't work. See
> > the initial report:
> >
> > 	http://lists.openvz.org/pipermail/criu/2015-April/019859.html
>
> What about something like the attached? Of course, this will break my
> test and make things in general much harder to test, but I think it is
> ok.

Well. I can't really comment it. At least right now. probably never...

But,

> To avoid this, we simply don't allow --ext-mount-map auto on non-pivot_rooted
> tasks,

OK. Lets forget about "--ext-mount-map auto" for the moment. Let me repeat
the quiestion I have already asked.

If I start mysqld under systemd it runs with unshared mnt ns and

	# grep systemd-private /proc/`pidof mysqld`/mountinfo

shows:

	47 36 253:1 /tmp/systemd-private-FgmebS/tmp /tmp rw,relatime shared:18 master:1 - xfs /dev/mapper/rhel_ibm--x3650m4--02--vm--02-root rw,seclabel,attr2,inode64,noquota
	48 36 253:1 /var/tmp/systemd-private-AKz2QT/tmp /var/tmp rw,relatime shared:19 master:1 - xfs /dev/mapper/rhel_ibm--x3650m4--02--vm--02-root rw,seclabel,attr2,inode64,noquota
	
Now,

	# criu dump -D D/ -j -t `pidof mysqld`
	Error (mount.c:912): Mount 48 ./var/tmp (master_id: 1 shared_id: 19) has unreachable sharing. Try --enable-external-masters.
	Error (cr-dump.c:1943): Dumping FAILED.

OK, lets try "--enable-external-masters" as the error message suggests ;)

	# criu dump -D D/ -j -t `pidof mysqld` --enable-external-masters
	must specify --ext-mount-map auto with --enable-external-{sharing|masters}

So. criu asks for "--ext-mount-map auto" but it will fail with this change?

How can I dump mysqld then?

Oleg.