On 06/06/2014 05:51 AM, Peter Krempa wrote:
> On 06/06/14 00:52, Eric Blake wrote:
>> Now that qemu 2.0 allows commit of the active layer, people are
>> attempting to use virsh blockcommit and getting into a stuck
>> state, because libvirt is unprepared to handle the two-phase
>> commit required by qemu.
>>
>> This patch adds a flag to the libvirt API that a user MUST
>> supply in order to acknowledge that they will be using two-phase
>> semantics. It might be possible to have a mode where if the
>> flag is omitted, we automatically do the case 2 semantics on
>> the user's behalf; but before that happens, I must do additional
>> patches to track the fact that we are doing an active commit
>> in the domain XML. Later patches will add support of the flag,
>> and once 2-phase semantics are working, we can then decide
>> whether to relax things to allow an omitted flag to cause an
>> automatic pivot.
>>
>> + /* XXX Should we auto-pivot when COMMIT_ACTIVE is not specified? */
>
> I think we should do it in the future and possibly document the expected
> behavior.
>
>> + if (!(flags & VIR_DOMAIN_BLOCK_COMMIT_ACTIVE)) {
>> + virReportError(VIR_ERR_INVALID_ARG,
>> + _("commit of '%s' active layer requires active flag"),
>> + disk->dst);
>> + goto endjob;
>> + }
>> }
>>
>> if (!topSource->backingStore) {
>
> ACK, adding the docs for the auto-pivot commit if you don't specify any
> flag can be postponed.
Agreed - we can document the new semantics once they are implemented.
I've pushed this patch now to reserve the bit, even though I still need
to post a v3 of the rest of the series with changes such as ensuring the
persistent definition is updated appropriately.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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