can not delete an instance if the instance's rescue volume is not found

[Eli Qiao]

can not delete an instance if the instance's rescue lvm can not be found.

how to reproduce:

1. configure images_type lvm for libvirt dirver.
[libvirt]
images_type = lvm <----
images_volume_group = stack-volumes-lvmdriver-1 <-- lvm used

2. rescue the instance, will generate uuid.rescue lvm
3. unrescue the instance, the rescue lvm can not be deleted due to bug https://bugs.launchpad.net/nova/+bug/1385480
4. delete the uuid.rescue lvm manually.
5. delete the instance(failed and set to error state)

below is the call trace of nova-compute driver.

2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher self._cleanup_lvm(instance)
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 944, in _cleanup_lvm
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher lvm.remove_volumes(disks)
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher File "/opt/stack/nova/nova/virt/libvirt/lvm.py", line 272, in remove_volumes
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher clear_volume(path)
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher File "/opt/stack/nova/nova/virt/libvirt/lvm.py", line 250, in clear_volume
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher volume_size = get_volume_size(path)
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher File "/opt/stack/nova/nova/virt/libvirt/lvm.py", line 66, in decorated_function
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher return function(path)
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher File "/opt/stack/nova/nova/virt/libvirt/lvm.py", line 197, in get_volume_size
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher run_as_root=True)
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher File "/opt/stack/nova/nova/virt/libvirt/utils.py", line 53, in execute
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher return utils.execute(*args, **kwargs)
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher File "/opt/stack/nova/nova/utils.py", line 164, in execute
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher return processutils.execute(*cmd, **kwargs)
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib/python2.7/site-packages/oslo_concurrency/processutils.py", line 224, in execute
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher cmd=sanitized_cmd)
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher ProcessExecutionError: Unexpected error while running command.
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher Command: sudo nova-rootwrap /etc/nova/rootwrap.conf blockdev --getsize64 /dev/stack-volumes-lvmdriver-1/b09687ee-f525-4edc-aaf4-1272562d46fd_disk.rescue
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher Exit code: 1
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher Stdout: u''
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher Stderr: u'blockdev: cannot open /dev/stack-volumes-lvmdriver-1/b09687ee-f525-4edc-aaf4-1272562d46fd_disk.rescue: No such file or directory\n'
2014-12-22 13:18:29.691 TRACE oslo.messaging.rpc.dispatcher

[Eli Qiao (taget-9)]

beside , in this case the error instance can not be deleted any more.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/143374

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/143374
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=11fb3936a1ad01af2a96a4eb4c00d1b158bd6f40
Submitter: Jenkins
Branch: master

commit 11fb3936a1ad01af2a96a4eb4c00d1b158bd6f40
Author: Eli Qiao <email address hidden>
Date: Mon Feb 16 11:23:42 2015 +0800

    Libvirt: Allow missing volumes during delete

    When deleting an instance, libvirt driver will clear all the volumes
    of the instance. Ignore exception when clearing a missing volume
    to avoid delete instance error.

    Closes-Bug: 1404791
    Change-Id: I8a663e8f0396bf2303642610ae1001c330159b75