Comment 2 for bug 1475007

Reviewed: https://review.openstack.org/203780
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=a95fef70b407a400c27195bd1cfbf09858511e9f
Submitter: Jenkins
Branch: master

commit a95fef70b407a400c27195bd1cfbf09858511e9f
Author: Erlon R. Cruz <email address hidden>
Date: Fri Jul 10 15:36:22 2015 -0300

    Fix concurrent attaches on HNAS iSCSI driver

    It might happen that multiple cinder nodes/backends are trying to add
    volumes to the same target. In this situation, the driver can get an
    error trying to add a volume to a hlun just taken by other instance.
    This patch fix this avoiding concurrency using mutual exclusion and adds
    retries to the failed attempts to cover scenarios where multiple cinder
    hosts are used.

    Closes-bug: #1475007
    Change-Id: Ie2d3b286eecbf0299ac0c0e32d3e098bb5d11e4f