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