Cannot recognize warning messages from "multipath -l"

[Tomoki Sekiyama]

If use_multipath_for_image_xfer=True is specified in cinder.conf, a volume is attached to transfer images from/to volumes using "multipath -l" or "multipath -ll" command to find the multipath device. However, in some configuration, "multipath -l" command may report an error like below:

 # multipath -l
 Mar 17 12:31:18 | sda: No fc_host device for 'host-1'
 mpathb (360000000000000000e00000000010001) dm-4 IET ,VIRTUAL-DISK
 size=1.0G features='0' hwhandler='0' wp=rw
 |-+- policy='service-time 0' prio=0 status=active
 | `- 2:0:0:1 sda 8:0 active undef running
 `-+- policy='service-time 0' prio=0 status=enabled
   `- 3:0:0:1 sdb 8:16 active undef running

Current multipath parser implementation in Nova and Cinder cannot recognize this warning message and regards "Mar" a valid multipath device name. As a result, the volume cannot be attached to the host correctly.

It is treated by MULTIPATH_ERROR_REGEX in cinder/brick/initiator/linuxscsi.py, but not in _get_multipath_device_name() in connector.py.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/165460
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=c93ba4230dd5e4e623cf6317df17deaa562d08c3
Submitter: Jenkins
Branch: master

commit c93ba4230dd5e4e623cf6317df17deaa562d08c3
Author: tsekiyam <email address hidden>
Date: Tue Mar 17 19:59:08 2015 -0400

    Remove error messages from multipath command output before parsing

    This fixes an issue in _get_multipath_device_name() that fails to
    parse the output from 'multipath -ll <device>' command when the
    stdout contains error messages in addition to the expected output.

    Change-Id: I498edd950627daca01eaf6343e6d742440ca4b04
    Related-Bug: #1380742
    Closes-Bug: #1433202