Unable to attach a volume to instances when DM Multipath user_friendly_names are enabled.

Issue

• Unable to attach a volume to instances when DM Multipath user_friendly_names are enabled.
• The following TRACE is seen in the /var/log/nova/nova-compute.log log of a host when attempting to attach a volume to an instance :

2015-03-31 22:36:22.022 18828 TRACE oslo.messaging.rpc.dispatcher   File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 122, in execute
2015-03-31 22:36:22.022 18828 TRACE oslo.messaging.rpc.dispatcher     six.reraise(c, e, tb)
2015-03-31 22:36:22.022 18828 TRACE oslo.messaging.rpc.dispatcher   File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 80, in tworker
2015-03-31 22:36:22.022 18828 TRACE oslo.messaging.rpc.dispatcher     rv = meth(*args, **kwargs)
2015-03-31 22:36:22.022 18828 TRACE oslo.messaging.rpc.dispatcher   File "/usr/lib64/python2.7/site-packages/libvirt.py", line 439, in attachDeviceFlags
2015-03-31 22:36:22.022 18828 TRACE oslo.messaging.rpc.dispatcher     if ret == -1: raise libvirtError ('virDomainAttachDeviceFlags() failed', dom=self)
2015-03-31 22:36:22.022 18828 TRACE oslo.messaging.rpc.dispatcher libvirtError: Failed to open file '/dev/mapper/360002ac000000000000000de00003b48': No such file or directory
2015-03-31 22:36:22.022 18828 TRACE oslo.messaging.rpc.dispatcher
2015-03-31 22:36:24.601 18828 DEBUG nova.openstack.common.periodic_task [-] Running periodic task ComputeManager._check_instance_build_time run_periodic_tasks /usr/lib/python2.7/site-packages/nova/openstack/common/periodic_task.py:193