[libvirt] [RFC v2 0/4] LXC with block device and enabled userns

[Daniel P. Berrangé]

On Wed, Jun 13, 2018 at 03:18:02PM +0100, Radostin Stoyanov wrote:

> > Ideally qemu-nbd would automatically exit when the last use of /dev/nbdNNN
> > was release (ie when filesystem was unmounted). This is something you can
> > enable for loopback devices, but I'm not sure it works for NBD. THis would
> > be a useful kernel enhancement if someone feels adventurous.
> It seems like qemu-nbd terminates automatically when the last client
> disconnects.

Right, but in the case where the kernel has connected qemu-nbd to a block
device, the kernel itself is a client that won't exit.

So what I was describing was that the kernel should automatically delete
the /dev/ndb0 device when the last mount was unmounted, and thus in turn
it can close the last client of qemu-nbd

> 
> https://git.qemu.org/?p=qemu.git;a=blob;f=qemu-nbd.c;h=51b9d38c72732c821cb4ee5bf362533406ce2494;hb=HEAD#l341
> 
> I will send a patch thattakes qemu-nbd out of the cgroups and
> disconnects qemu-nbd on container shutdown.
> 
> Radostin
> 

Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|