Comment 3 for bug 1922408

1:create an encrypted rbd volume A, which size is 2G.
2:create A's snapshot snap_A.
3:create new encrypted volume B form snap_A, the size of B is 2G too.

def create_volume_from_snap():
...
    if int(volume.size)
       self._resize(volume)
...

before exec _resize the size of B is 2G + 1M, after exec _resize. B will be truncate to 2G
,this operation would cut the header, after resize operation, use cryptsetup Dumpluks this volume
,will not found encryption header.

the possilbel resolve: https://review.opendev.org/c/openstack/cinder/+/784623