Description of problem:

Doing 'deactive' of disk on running VM fails with hotunplugDisk timeout. Odd, I just "hot"-added that disk to the VM couple of seconds before doing 'deactivate' action in UI.

~~~
[root@dell-r210ii-13 site-packages]# grep hotunplugDisk /var/log/vdsm/vdsm.log  | tail -n 8
jsonrpc.Executor/2::DEBUG::2016-11-03 11:51:00,180::__init__::530::jsonrpc.JsonRpcServer::(_handle_request) Calling 'VM.hotunplugDisk' in bridge with {u'params': {u'vmId': u'33d37a3a-0dbb-4c25-8ae8-14d55c07614e', u'drive': {u'domainID': u'000f2622-ffad-4b89-b318-9c2dcb4e50fb', u'format': u'raw', u'type': u'disk', u'poolID': u'00000001-0001-0001-0001-0000000000d9', u'volumeID': u'0452d424-79d0-417b-ace6-227aff5bc77e', u'imageID': u'89e2826c-b250-4244-b0f1-e0cd08ee2df9', u'specParams': {}, u'readonly': u'false', u'iface': u'virtio', u'deviceId': u'89e2826c-b250-4244-b0f1-e0cd08ee2df9', u'address': {u'function': u'0x0', u'bus': u'0x00', u'domain': u'0x0000', u'type': u'pci', u'slot': u'0x08'}, u'device': u'disk', u'shared': u'false', u'propagateErrors': u'off', u'optional': u'false'}}, u'vmID': u'33d37a3a-0dbb-4c25-8ae8-14d55c07614e'}
jsonrpc.Executor/2::INFO::2016-11-03 11:51:00,196::vm::2947::virt.vm::(hotunplugDisk) vmId=`33d37a3a-0dbb-4c25-8ae8-14d55c07614e`::Hotunplug disk xml: <disk device="disk" snapshot="no" type="file">
jsonrpc.Executor/2::ERROR::2016-11-03 11:51:35,321::vm::2955::virt.vm::(hotunplugDisk) vmId=`33d37a3a-0dbb-4c25-8ae8-14d55c07614e`::Timeout detaching device vdb
jsonrpc.Executor/2::INFO::2016-11-03 11:51:35,322::__init__::513::jsonrpc.JsonRpcServer::(_serveRequest) RPC call VM.hotunplugDisk failed (error 46) in 35.14 seconds
jsonrpc.Executor/0::DEBUG::2016-11-03 11:52:45,619::__init__::530::jsonrpc.JsonRpcServer::(_handle_request) Calling 'VM.hotunplugDisk' in bridge with {u'params': {u'vmId': u'33d37a3a-0dbb-4c25-8ae8-14d55c07614e', u'drive': {u'domainID': u'000f2622-ffad-4b89-b318-9c2dcb4e50fb', u'format': u'raw', u'type': u'disk', u'poolID': u'00000001-0001-0001-0001-0000000000d9', u'volumeID': u'0452d424-79d0-417b-ace6-227aff5bc77e', u'imageID': u'89e2826c-b250-4244-b0f1-e0cd08ee2df9', u'specParams': {}, u'readonly': u'false', u'iface': u'virtio', u'deviceId': u'89e2826c-b250-4244-b0f1-e0cd08ee2df9', u'address': {u'function': u'0x0', u'bus': u'0x00', u'domain': u'0x0000', u'type': u'pci', u'slot': u'0x08'}, u'device': u'disk', u'shared': u'false', u'propagateErrors': u'off', u'optional': u'false'}}, u'vmID': u'33d37a3a-0dbb-4c25-8ae8-14d55c07614e'}
jsonrpc.Executor/0::INFO::2016-11-03 11:52:45,634::vm::2947::virt.vm::(hotunplugDisk) vmId=`33d37a3a-0dbb-4c25-8ae8-14d55c07614e`::Hotunplug disk xml: <disk device="disk" snapshot="no" type="file">
jsonrpc.Executor/0::ERROR::2016-11-03 11:53:20,757::vm::2955::virt.vm::(hotunplugDisk) vmId=`33d37a3a-0dbb-4c25-8ae8-14d55c07614e`::Timeout detaching device vdb
jsonrpc.Executor/0::INFO::2016-11-03 11:53:20,758::__init__::513::jsonrpc.JsonRpcServer::(_serveRequest) RPC call VM.hotunplugDisk failed (error 46) in 35.14 seconds
~~~

Version-Release number of selected component (if applicable):
libvirt-daemon-2.0.0-10.el7.x86_64
vdsm-4.18.15.2-1.el7ev.x86_64
redhat-release-server-7.2-9.el7_2.1.x86_64 / redhat-release-server-7.3-7.el7.x86_64
python-2.7.5-48.el7.x86_64
ovirt-engine-backend-4.0.5.5-0.1.el7ev.noarch

How reproducible:
100%

Steps to Reproduce:
1. create a vm without disk, start that vm
2. add disk to running vm
3. deactivate the disk of this running vm

Actual results:
fails

Expected results:
should work

Additional info: