[libvirt] [PATCH] util: Remove empty resource partition created by libvirt

[Daniel P. Berrange]

On Wed, Aug 12, 2015 at 11:09:12AM +0530, Nikunj A Dadhania wrote:
> 
> Hi Daniel,
> 
> "Daniel P. Berrange" <berrange at redhat.com> writes:
> > On Tue, Aug 11, 2015 at 04:57:15PM +0530, Nikunj A Dadhania wrote:
> >> The default resource partition is created in the domain start path if it
> >> is not existing. Even when libvirtd is stopped after shutting down all
> >> domains, the resource partition still exists.
> >> 
> >> The patch adds code to removes the default resource partition in the
> >> cgroup removal path of the domain. If the default resource partition is
> >> found to have no child cgroup, the default resource partition will be
> >> removed.
> >> 
> >> Moreover, the code does not remove the user provided resource
> >> partitions.
> >> 
> >> Signed-off-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>
> >
> > I don't think we want to be doing this. In non-systemd hosts this will
> > be deleting the heirarchy that the sysadmin manually pre-created for
> > their VMs.  In a systemd host it will also end up deleting slices that
> > were created by systemd.
> 
> AFAIU, there are three cases here:
> 
> 1) User created resource partition, for example /production/foo
>    As this is created by user, we should not touch them. And my patch
>    does not remove them
>    
> 2) systemd created /machine.slice
>    If not libvirt, should systemd clean this up when the libvirtd
>    service is stopped ?
> 
>    Currently, my patch does remove this when its found empty

It isn't libvirtd's job to delete /machine.slice - systemd will
periodically prune empty slices itself.

> 3) libvirt created /machine
>    As this was created manually by libvirt, should we delete it here in
>    libvirt daemon

No, you can't assume /machine is created by libvirtd - it could have
been created by the user, just like case 3.


Regards,
Daniel
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