Full versions of libvirt/qemu packages installation

Make sure that your libvirt supports the virsh blockcommit operation. CentOS distribution requires you to install the full libvirt and qemu-img from the oVirt repository. This can be done like this:

1. Install oVirt repo:

yum install http://resources.ovirt.org/pub/yum-repo/ovirt-release42.rpm -y

2. Update the packages

yum update -y

which should replace qemu related packages with full versions from the oVirt repo.