Volumes made from image cache are snapshotted backwards

[rmb938]

This is a weird one, it may be an Openstack issue and not an issue with this driver.

1. Set image_volume_cache_enabled = True for this driver and start with no images currently cached.
2. Launch an instance so it creates a volume of the provided image, i.e

    resource "openstack_compute_instance_v2" "boot-from-volume" {
      name            = "boot-from-volume"
      flavor_id       = "1"
      key_pair        = "mykey"
      security_groups = ["default"]
      config_drive    = true
    
      block_device {
        uuid                  = "5cb160aa-5e5f-46e8-a217-a30135bed695"
        source_type           = "image"
        volume_size           = 50
        boot_index            = 0
        volume_type           = "ixsystems-iscsi"
        destination_type      = "volume"
        delete_on_termination = true
      }

3. Delete the instance

The volume that was made for the instance will get stuck in Error Deleting, see screenshot of the instance volume + the image cache volume in horizon + in truenas UI:

In the truenas UI I see there is a snapshot on the instance volume.

Per testing, this snapshot gets created when the image is cached, then is used to create a zvol for the cached image.

This seems a bit backwards to me. I would expect the volume to be created in openstack, zvol created in truenas which is the cached image, snapshot taken of that, then a new zvol created from that snapshot for the instance disk. But it seems to be taking a snapshot of the instance's volume to cache the image.

If I delete the image-5cb160aa-5e5f-46e8-a217-a30135bed695 volume, then reset the sate of 9f6a6172-27ba-4afc-ad02-28c826d8ec86 then delete 9f6a6172-27ba-4afc-ad02-28c826d8ec86 everything works fine. So I beleive it's due to this snapshot on the instance volume due to the image cache.

[rmb938]

It seems like I can "fix" the issue by promoting the "volume-45c47a88" dataset in the UI.

[YiHuangDB]

Hi Ryan, this issue is not fixed by PR#35 #35, with latest master branch code, cache volume now managed by driver properly by promoting the volume. Thank you for reporting this issue. -Yi