What were you trying to do that didn't work?

A limited deployment of libvirt which lacks storage driver packages (such as used by CNV) is unable to do some operations which create storage volumes, such as external snapshots or backups.

The problem is that those operations use the 'fs' "storage file" backend, which is distributed in the "libvirt-daemon-driver-storage-core" package. As there are no fallbacks on some code paths, weird errors are reported. Technically the 'fs' backend uses code that is already compiled into libvirt anyways so having it as a module doesn't make too much sense.

In order to not force CNV to install the storage driver the 'fs' backend should be compiled in instead.

What is the impact of this issue to you?

Please provide the package NVR for which the bug is seen:

libvirt-daemon-driver-qemu-10.10.0-2

How reproducible is this bug?:

always

Steps to reproduce

1. Deploy libvirt such that only the libvirt-daemon-driver-qemu package and it's dependencies (As well as qemu-kvm) is installed while libvirt-daemon-driver-storage-core is not installed. Make sure to install also the clients such as virsh via libvirt-client package
2. Start a VM with at least 1 disk
3. Try to do a backup. E.g. with following XML:

   <domainbackup>
       <disks>
           <disk name='vda' backup='yes'/>
       </disks>
   </domainbackup>
   
   virsh backup-begin VMNAME XMLPATH
    

Expected results

backup is created successfully

Actual results

 error: internal error: unable to execute QEMU command 'blockdev-add': Could not open '/run/kubevirt-private/vmi-disks/fspvc/qcow2overlay.qcow2.since-backup-default_vmfedora-3': No such file or directory