[Devel] [Q] migrating inotify assigned on ploop device

[Cyrill Gorcunov]

On Tue, Jan 12, 2016 at 03:12:15PM +0400, Nikita Spiridonov wrote:
> On Tue, 2016-01-12 at 13:49 +0300, Cyrill Gorcunov wrote:
> > On Tue, Jan 12, 2016 at 01:30:28PM +0300, Pavel Emelyanov wrote:
> > > 
> > > Plz read my last chapter:
> > > 
> > > > Should we work on images copy instead? Which gonna be horrible design :)
> > > > 
> > > >>
> > > >> On restore we need to patch criu to spawn crit with recode action and
> > > >> necessary recode rules. CRIT then would read data from images and write
> > > >> them back to criu via pipe.
> > > 
> > > crit writes modified data into pipe that goes to criu instead of opened
> > > image fd.
> > 
> > Managed to miss it, thanks!
> 
> So, finally, we must patch criu and enable that recoding passing some
> command line option from libvzctl to fix issue?

I think so. We need to invent some kind of such protocol to be suitable
for use with p.haul and libvzctl, the criu itself should not be changed
I think. For criu it like some extrrnal modifications.

As to performance: we don't have to patch "all" images (really huge
data sits in "page" images) but only those which might be affected by
device name mapping. In particular:

 - reg-files
 - inotify
 - mount points

and maybe someone else. Pavel said he tried "recode" testing in CRIT
and it works pretty fast. Not sure though which exactly tests were running.

	Cyrill