Volume is fully allocated after storage class migration - hostpath-csi-basic 

CNV-v4.21.0.rhel9-127

Always 

1. Create a VM with hostpath-csi-basic 
2. Login the virt-launcher pod 
$ oc rsh virt-launcher-fedora-hpp-5kkrd
sh-5.1$ qemu-img info /var/run/kubevirt-private/vmi-disks/rootdisk/disk.img 
image: /var/run/kubevirt-private/vmi-disks/rootdisk/disk.img
file format: raw
virtual size: 30 GiB (32212254720 bytes)
disk size: 1.16 GiB
Child node '/file':
    filename: /var/run/kubevirt-private/vmi-disks/rootdisk/disk.img
    protocol type: file
    file length: 30 GiB (32212254720 bytes)
    disk size: 1.16 GiB 2. Migrate to the same Storage class
3. Migrate to the same sc hostpath-csi-basic 
4. After migration completed, check the disk again
 

The volume is full allocated. And the disk size increased. 
sh-5.1$  qemu-img info /var/run/kubevirt-private/vmi-disks/rootdisk/disk.img
image: /var/run/kubevirt-private/vmi-disks/rootdisk/disk.img
file format: raw
virtual size: 31.8 GiB (34145828864 bytes)
disk size: 31.7 GiB  
Child node '/file':
    filename: /var/run/kubevirt-private/vmi-disks/rootdisk/disk.img
    protocol type: file
    file length: 31.8 GiB (34145828864 bytes)
    disk size: 31.7 GiB
    Format specific information:
        extent size hint: 1048576

The destination volume should have nearly the same size as the source volume

OCS -> OCS : works well