Race conditions on xtremio with client3

[Gorka Eguileor]

Description of problem:
When working with FC and xtremio is using XtremIOClient3 on FC's terminate_connection we can get exceptions where we shouldn't:

    VolumeBackendAPIException: Bad or unexpected response from the storage volume backend API: Unable to terminate volume connection: Resource could not be found.

Expected behavior:
terminate_connection should complete without raising any exception.

Cause:
Client3 is open to race conditions on 2 methods, find_lunmap and num_of_mapped_volumes, where a list of mappings is first retrieved and then we iterate this list to retrieved additional info on the mappings.

The race would happen if one of the mappings is removed from the backend in the time it takes to retrieve the additional info after we have retrieved the list.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/251305

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/251305
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=89480f159231eae154119da6b46432849b9df20a
Submitter: Jenkins
Branch: master

commit 89480f159231eae154119da6b46432849b9df20a
Author: Gorka Eguileor <email address hidden>
Date: Mon Nov 30 12:04:58 2015 +0100

    Take into consideration races in XtremIOClient3

    When working with FC and xtremio is using XtremIOClient3 on FC's
    terminate_connection we can get VolumeBackendAPIException saying a
    resource could not be found when we shouldn't.

    The cause is that Client3 is open to race conditions on 2 methods,
    find_lunmap and num_of_mapped_volumes, where a list of mappings is first
    retrieved and then we iterate this list to retrieved additional info on
    the mappings.

    The race would happen if one of the mappings is removed from the backend
    in the time it takes to retrieve the additional info after we have
    retrieved the list.

    This patch fixes this issue by ignoring any mappings that have been
    removed and are now NotFound when retrieving additional information for
    a mapping in those 2 methods.

    This patch also fixes this kind of race problems on volume creation
    since it uses find_lumap method.

    Closes-Bug: #1521143
    Change-Id: I40831e04093ff475395870a333211dd0cb60440f

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/liberty
Review: https://review.openstack.org/252360

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/252360
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=2c12909705e2536dd39f22096167fbf5e4719e2e
Submitter: Jenkins
Branch: stable/liberty

commit 2c12909705e2536dd39f22096167fbf5e4719e2e
Author: Gorka Eguileor <email address hidden>
Date: Mon Nov 30 12:04:58 2015 +0100

    Take into consideration races in XtremIOClient3

    When working with FC and xtremio is using XtremIOClient3 on FC's
    terminate_connection we can get VolumeBackendAPIException saying a
    resource could not be found when we shouldn't.

    The cause is that Client3 is open to race conditions on 2 methods,
    find_lunmap and num_of_mapped_volumes, where a list of mappings is first
    retrieved and then we iterate this list to retrieved additional info on
    the mappings.

    The race would happen if one of the mappings is removed from the backend
    in the time it takes to retrieve the additional info after we have
    retrieved the list.

    This patch fixes this issue by ignoring any mappings that have been
    removed and are now NotFound when retrieving additional information for
    a mapping in those 2 methods.

    This patch also fixes this kind of race problems on volume creation
    since it uses find_lumap method.

    Closes-Bug: #1521143
    Change-Id: I40831e04093ff475395870a333211dd0cb60440f
    (cherry picked from commit 89480f159231eae154119da6b46432849b9df20a)

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/cinder 8.0.0.0b1 development milestone.

[Thierry Carrez (ttx)]

This issue was fixed in the cinder 7.0.1 release (liberty).