remove_export after changing volume to available

[Lisa Li]

In master branch with lvm as backend storage:

During detach_volume, Cinder at first sets volume in available status and then removes iscsi targets.

set volume in available: https://github.com/openstack/cinder/blob/master/cinder/volume/manager.py#L1093

remove export: https://github.com/openstack/cinder/blob/master/cinder/volume/manager.py#L1108

This leads following problem:
1. Attach volume to instance 1.
2. Detach volume from instance 1.
3. At the time (when volume becomes available, and before removing remove_export) attach the volume to instance 2.
4. Is is possible that when isci target is created for instance 2, but remove_export for instance 1 removes the just created iscsi target.

As a result, attach volume to intance 2 fails.

This ever leaded CI fails http://logs.openstack.org/92/355392/4/gate/gate-tempest-dsvm-postgres-full-ubuntu-xenial/582fbd7/logs/screen-c-vol.txt.gz?level=WARNING

This exists in LVM, I am not sure whether other backend storages have same problem.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/360211

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/360211
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=c3b33b6a23c885853d28cb340a394d72cd18839a
Submitter: Jenkins
Branch: master

commit c3b33b6a23c885853d28cb340a394d72cd18839a
Author: lisali <email address hidden>
Date: Thu Aug 25 12:03:31 2016 +0800

    Recover volume status after remove_export

    Currently Cinder recover volume's status before remove_export,
    which leads that recreated iSCSI targets may be deleted and
    attachment fails.

    Let's consider the case: A volume is attached to instance A, and then
    detached. During detach, Cinder sets volume's status to available and
    remove iSCSI targets.
    At the exact time the volume is reset to
    available but targets are not removed, the volume is attached to
    instance 2 and targets are created again. And then former remove_export
    removed the recreated targets, and then it leads attachment fail.

    This patch is to move remove_export after changing volume's
    status.

    Change-Id: I914d4badd9b93e9dc8f4ebc4f74314afe95bf855
    Closes-Bug: #1616719

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinder 9.0.0.0rc1 release candidate.