Volume is not detached when deleted VM was in error state

[Bruno Grazioli]

When creating a VM with multiple volumes - from a snapshot - if quota is exceeded nova will fail to launch the VM. When the VM is deleted the volumes created are not detached - attached to None.

Steps to reproduce:
1. Create a VM (creating a new volume) and attach 2 volumes to it.
2. Create a snapshot of the VM.
3. Set the volume quota to 5.
4. Create a new VM based on the snapshot from step 2.
5. VM will get into error state but when it gets removed volumes will still be associated with 'None'.

Expected:
Instance deleted and volume detached.

Actual:
Instance deleted and volume attached to 'None'.

In our deployment - which is stable/ocata - we had an issue with the bug #1668267. Maybe this is related to this.

For sake of completeness, we are running Openstack with ceph.

[Matt Riedemann (mriedem)]

So if I'm following correct, you have 3 volumes when you snapshot the instance, then set volume quota to 5, create another instance from the snapshot image which has 3 image-defined BDMs in it.

Since it's boot from volume, nova-compute is what creates the 3 volumes from volume snapshots. 2 of those volumes would get created and the 3rd would be rejected by cinder because of over quota. That makes the _prep_block_devices method in the compute service fail and set the instance to ERROR state. I'm not sure if 2 of those 3 volumes would be attached or not, and I guess that's the bug. Maybe they aren't in a state that compute knows how to properly clean them up. It probably also matters what the delete_on_termination value is in those bdms to see if compute would remove them.

[Bruno Grazioli (bwg-bruno-5)]

That's correct.

>> I'm not sure if 2 of those 3 volumes would be attached or not, and I guess that's the bug.

The 2 volumes are attached to the VM but do not get detached when the VM is terminated.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/528069

[OpenStack Infra (hudson-openstack)]

Change abandoned by Ameed Ashour (<email address hidden>) on branch: master
Review: https://review.openstack.org/528069
Reason: duplicated with Mel's patch https://review.openstack.org/#/c/340614/