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.*/ ........ }
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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#virDomainDetachDeviceFla... 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