Comment 4 for bug 1739442

I'm facing this issue while working with NFS encrypted volumes.
The nova code [1] formats a qcow2 volume to raw, making the instance's creation fail.

ERROR nova.compute.manager [None req-0c7bdd37-43b5-4b42-b34f-2ac732d2d34f tempest-TestVolumeBootPattern-119732072 tempest-TestVolumeBootPattern-119732072-project] [instance: 014999b2-f a06-4dc5-af55-213f544165f9] Instance failed to spawn: libvirt.libvirtError: internal error: qemu unexpectedly closed the monitor: 2022-08-03T14:38:41.513419Z qemu-system-x86_64: -blockdev {"node-name":"libvirt-1-format","read-only":fa lse,"cache":{"direct":true,"no-flush":false},"driver":"qcow2","encrypt":{"format":"luks","key-secret":"libvirt-1-format-luks-secret0"},"file":"libvirt-1-storage","backing":null}: Image is not in qcow2 format
 24 Aug 03 14:38:42 enriquetaso nova-compute[197128]: ERROR nova.compute.manager [instance: 014999b2-fa06-4dc5-af55-213f544165f9] Traceback (most recent call last):

[1]: https://opendev.org/openstack/nova/src/branch/master/nova/virt/libvirt/driver.py#L2065