if all backend down, the status of share will stuck in "extending" when we extend an share

[haixin]

In the process of extending share, i found extend share api use rpc direct call share manager to execute extend. But if manila-share lose connection to backend storage or manila-share service is down. the status of share will stuck in extending. This is an intermediate state, So I don't think that's reasonable.
i think we can use scheduler layer instead of direct call share manager, if allocation backend failed, the status of share will rollback to "available". and user messages will record this anomaly, which will help user to know why extend share not success.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/700393

[Vida Haririan (vhariria)]

Additional comments http://eavesdrop.openstack.org/meetings/manila/2020/manila.2020-04-30-15.00.log.html

[Vida Haririan (vhariria)]

Additional comments http://eavesdrop.openstack.org/meetings/manila/2020/manila.2020-05-28-15.00.log.html

[Maurice Escher (maurice-escher)]

Above discussion went on in http://eavesdrop.openstack.org/irclogs/%23openstack-manila/%23openstack-manila.2020-05-28.log.html#t2020-05-28T16:02:43

[Vida Haririan (vhariria)]

Additional comments http://eavesdrop.openstack.org/meetings/manila/2021/manila.2021-02-11-15.00.log.html

[Goutham Pacha Ravi (gouthamr)]

Fix proposed to branch master:
    https://review.opendev.org/c/openstack/manila/+/700393

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/manila/+/700393
Committed: https://opendev.org/openstack/manila/commit/cdbc428b692ca087e26fa1ab5c3d1f5fb77cdc29
Submitter: "Zuul (22348)"
Branch: master

commit cdbc428b692ca087e26fa1ab5c3d1f5fb77cdc29
Author: haixin <email address hidden>
Date: Mon Dec 23 16:33:04 2019 +0800

    Extend share will go through scheduler

    Add an force parameter to the API layer that lets the user choose
    whether to go through the scheduler or not, which is boolean.and
    default is False,set True means extend share directly, set False
    means extend share will go through scheduler.
    Add an new min_version 2.64 to extend share api. force parameter
    only support min_version >= 2.64.

    Closes-Bug:#1855391
    Change-Id: I6da36a687a37c78a7fb7d3f252318d03d4a05133

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/manila 13.0.0.0rc1 release candidate.