[libvirt] [PATCH 0/7] Add support for qcow2 backing files to sVirt

Hey, https://bugzilla.redhat.com/497131 shows that sVirt cannot currently handle qcow2 files with a backing store. Because we do not re-label the backing store, qemu cannot read it. The fix is fairly straightforward - when we go to re-label a file, check its header and if it has a backing store, re-label that too. Most of this series involves moving the header probing code from the storage driver into libvirt_util so that the security driver can use it. Cheers, Mark.