[libvirt] [PATCH v2 2/2] qemuDomainUndefineFlags: Forbid undefine of active domain with NVRAM

[Daniel P. Berrange]

On Wed, Aug 09, 2017 at 02:55:36PM +0200, Michal Privoznik wrote:
> On 08/09/2017 02:14 PM, Daniel P. Berrange wrote:
> > On Wed, Aug 09, 2017 at 02:00:06PM +0200, Michal Privoznik wrote:
> >> https://bugzilla.redhat.com/show_bug.cgi?id=1467245
> >>
> >> Currently, there's a bug when undefining a domain with NVRAM
> >> store. Basically, the unlink() of the NVRAM store file happens
> >> during the undefine procedure iff domain is inactive. So, if
> >> domain is running and undefine is called the file is left behind.
> >> It won't be removed in the domain cleanup process either
> >> (qemuProcessStop). To avoid this forbid undefining domain with
> >> NVRAM file.
> > 
> > Why do we need to forbid it ? Even if QEMU still has an open
> > file handle, it can continue to write to it after we unlink
> > it.
> > 
> > 
> 
> That's what my v1 does. Anyway, there's third option: just recently
> Jirka added possibility to do some actions when domain is destroyed. He
> needed it for some migration work, but the design is broad enough to fit
> this problem too. What we can do is:
> 
> if (flags & VIR_DOMAIN_UNDEFINE_NVRAM):
>   if domain is running:
>     register the callback /* that merely just unlinks the file */
>   else:
>     unlink
> else:
>   if (!(flags & VIR_DOMAIN_UNDEFINE_KEEP_NVRAM)):
>     error
> 
> 
> What do you guys think of this one?

The callback will be lost if libvirtd restarts.

Regards,
Daniel
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