[libvirt] [PATCH] metadata: track title edits across libvirtd restart

[Eric Blake]

On 07/22/2014 11:09 PM, Martin Kletzander wrote:
> On Tue, Jul 22, 2014 at 01:11:03PM -0600, Eric Blake wrote:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1122205
>>
>> Although the edits were changing in-memory XML, it was not flushed
>> to disk; so unless some other action changes XML, a libvirtd restart
>> would lose the changed information.
>>
> 
> And there are more places like that.  Take a
> qemuDomainSetNumaParameters() for example.

That's what I was afraid of - that I'd be stuck with auditing other uses
all because I stumbled on this one while testing a similar fix to
blockcopy. :/

>  Would it be possible (as
> in "not devastatingly hard" to create a syntax-check rule for
> *_driver.c files (only those that are applicable, mostly stateful)
> that would check if virCheckFlags is called with
> VIR_DOMAIN_AFFECT_LIVE and if yes, then that function would have to
> call virDomainSaveStatus() as well?

Via a .pl script maybe, but even that is hard, because sometimes (as in
this patch) the call to virDomainSaveStatus() is delegated to a helper
function in another file than where the API call checks flags.  It's not
just AFFECT_LIVE, but any time where we modify a virDomainDefPtr
(whether live or config), then those modifications have to be written
back to disk before ending the API.

> 
> [...]
>> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
>> index 4b00280..6ed6155 100644
>> --- a/src/conf/domain_conf.c
>> +++ b/src/conf/domain_conf.c
> [...]
>> @@ -19753,9 +19757,12 @@ virDomainObjSetMetadata(virDomainObjPtr vm,
>>                                         &persistentDef) < 0)
>>         return -1;
>>
>> -    if (flags & VIR_DOMAIN_AFFECT_LIVE)
>> +    if (flags & VIR_DOMAIN_AFFECT_LIVE) {
>>         if (virDomainDefSetMetadata(vm->def, type, metadata, key, uri)
>> < 0)
>>             return -1;
> 
> One empty line right here would perfectly go with the rest of the
> function ;)
> 
> ACK with or without this change,
> 
> Martin

Thanks, will push shortly.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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