On Tue, Jul 28, 2015 at 04:25:13PM +0800, zhang bo wrote:
> static int
> qemuDomainDetachVirtioDiskDevice(virQEMUDriverPtr driver,
> virDomainObjPtr vm,
> virDomainDiskDefPtr detach)
> {
> .......
>
> rc = qemuDomainWaitForDeviceRemoval(vm);
> if (rc == 0 || rc == 1)
> ret = qemuDomainRemoveDiskDevice(driver, vm, detach);
> else
> ret = 0; /*the return value of 2 is dismissed here, which refers to ETIMEOUT.*/
> ........
> }
>
> ------------------------------------
>
> If it timeouts when qemu tries to del the device, the return value would be modified from 2 to 0 in
> function qemuDomainDetachVirtioDiskDevice(), which means that, the users would be misleaded that
> the device has been deleted, however, the device maybe probably failed to be detached after timeout and
> still in use.
>
This is intentional and documented:
http://libvirt.org/html/libvirt-libvirt-domain.html#virDomainDetachDeviceFlags
Unplugging a disk requires guest cooperation, so the best we can do is
ask qemu to unplug it and wait for a while.
> That is to say, the function qemuDomainDetachVirtioDiskDevice()'s return value is ambiguous when it's 0,
> maybe successful, or timeout. Will it be better to pass ETIMEOUT to user? or any other advises? for example,
> let users themselves dumpxml the guest to check whether the device has been actually detached or not?
Either dump the XML, or wait for the VIR_DOMAIN_EVENT_ID_DEVICE_REMOVED
event, as the API documentation suggests.
Jan
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