[CRIU] v2: automatic detection of external bind mounts

[Pavel Emelyanov]

On 04/10/2015 12:13 AM, Tycho Andersen wrote:
> Hi Pavel,
> 
> On Thu, Apr 09, 2015 at 02:56:48PM -0600, Tycho Andersen wrote:
>>
>> Hmm, actually I found something wrong with this set. Please let me
>> debug it.
> 
> So the problem is the fsroot_mounted() check; I knew it wasn't in there for a
> reason :). I just tested the patch on the right (systemd) host and found the
> problem. For e.g. pstore (but also kernel security and a few others), I have a
> mountinfo entry in the container that looks like this:
> 
> 90 83 0:23 / /sys/fs/pstore rw,nosuid,nodev,noexec,relatime master:11 - pstore pstore rw
> 
> and on the host:
> 
> 29 17 0:23 / /sys/fs/pstore rw,nosuid,nodev,noexec,relatime shared:11 - pstore pstore rw
> 
> So, fsroot_mounted() is true, which means this mountpoint is never checked for
> external sharing as it should be. I'm not sure what the right answer is here;
> things work as I want them to if I leave the check out, but semantically the
> check seems to make sense (at least in the case where there is no sharing).
> Maybe that's the right answer, to only bail on fsroot_mounted() entries if
> there is no external sharing?

Ah, so this is fsroot shared mount %) Phew! Well, I think you were right about removing
the fsroot_mounted() check. In the end fsroot external mount shouldn't differ from
non-fsroot mount in this sense.

-- Pavel