No error message when volume extend fails

[Lucio Seki]

When an operator tries to extend a volume beyond its backend's capacity, he/she has no feedback whether the operation succeeded or failed.

Steps to reproduce:
1. Configure a backend with some capacity limitation LIMIT (e.g. 200GB);
2. Create a volume with size < LIMIT (e.g. 1GB);
3. Try to extend it above LIMIT (e.g. 250GB).

Expected behavior:
Get an error message somewhere.

Actual behavior:
No error message is given. The operator should look at the cinder scheduler log, which is not user-friendly.

[Lucio Seki (lseki)]

It would be nice if a user message was created, similar to the one created when volume creation fails:

$ # if it's asked to create a volume beyond backend's capacity...
$ cinder create --name v3 200

$ # no volume is created;
$ # and a user message is created, as expected
$ cinder --os-volume-api-version 3.3 message-list
+--------------------------------------+---------------+--------------------------------------+-----------------------+-------------------------------------------------------------------------+
| ID | Resource Type | Resource UUID | Event ID | User Message |
+--------------------------------------+---------------+--------------------------------------+-----------------------+-------------------------------------------------------------------------+
| 298c7c17-9e19-4386-a800-031aa490acfa | VOLUME | 604a5d03-4d2e-47c6-ad0d-b8e6ff6f80ab | VOLUME_VOLUME_001_003 | schedule allocate volume:Could not find any available weighted backend. |
+--------------------------------------+---------------+--------------------------------------+-----------------------+-------------------------------------------------------------------------+

[Sean McGinnis (sean-mcginnis)]

The extend API call is asynchronous, so that just returns whether the request was successfully received or not. But I agree, a user message should be added for async failures like this, similar to the work done in https://github.com/openstack/cinder/commit/848ff3ad86d03368ed3d1ce361bc55f5b10d3bd8

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/570837

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/570837
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=3aec5274da29c81c76bb7f87317160e32f9780ff
Submitter: Zuul
Branch: master

commit 3aec5274da29c81c76bb7f87317160e32f9780ff
Author: TommyLike <email address hidden>
Date: Tue May 29 12:17:39 2018 +0800

    Add user messages for extend volume operation

    Add user messages for these cases below when performing
    extend volume operation.
    1. When no valid host is found.
    2. When nova failed to perform extend volume event.
    3. When backend failed to extend block device.

    Change-Id: I7d2061ac13b2c74745da56feecfe6ed53b284fc4
    Closes-Bug: #1773833

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinder 13.0.0.0b2 development milestone.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/queens
Review: https://review.openstack.org/593202

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/593202
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=1f2e970c9f88554f958645029eaa7bfed63642cb
Submitter: Zuul
Branch: stable/queens

commit 1f2e970c9f88554f958645029eaa7bfed63642cb
Author: TommyLike <email address hidden>
Date: Tue May 29 12:17:39 2018 +0800

    Add user messages for extend volume operation

    Add user messages for these cases below when performing
    extend volume operation.
    1. When no valid host is found.
    2. When nova failed to perform extend volume event.
    3. When backend failed to extend block device.

    Change-Id: I7d2061ac13b2c74745da56feecfe6ed53b284fc4
    Closes-Bug: #1773833
    (cherry picked from commit 3aec5274da29c81c76bb7f87317160e32f9780ff)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinder 12.0.4 release.