Re: [libvirt] [PATCH 2/2] blockjob: properly track blockcopy xml changes on disk

On Mon, 2014-07-21 at 22:34 -0600, Eric Blake wrote: > We were not directly saving the domain XML to file after starting > or finishing a blockcopy. Without the startup write, a libvirtd > restart in the middle of a copy job would forget that the job was > underway. Then at pivot, we were indirectly writing new XML in > reaction to events that occur as we stop and restart the guest CPUs. > But there was a race: since pivot is an async action, it is possible > that the guest is restarted before the pivot completes, so if XML > changes during the event, that change was not written. The original > blockcopy code cleared out the <mirror> element prior to restarting > the CPUs, but this is also a race, observed if a user does an async > pivot and a dumpxml before the event occurs. Furthermore, this race > will interfere with active commit, because that code relies on the > <mirror> element at the time of the qemu event to determine whether > to inform the user of a normal commit or an active commit.

> +++ b/src/qemu/qemu_process.c > @@ -1016,6 +1016,7 @@ qemuProcessHandleBlockJob(qemuMonitorPtr mon ATTRIBUTE_UNUSED, > virObjectEventPtr event2 = NULL; > const char *path; > virDomainDiskDefPtr disk; > + virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); Hello Eric, The cfg should be unref by virObjectUnref(cfg) at the end.