I installed the proposed libvirt packages yesterday and was able to successfully create a live external snapshot and then flatten the snapshot back into the top-level image as follows:
1. virsh snapshot-create-as dns sn1 "snapshot1" --disk-only --atomic
2. virsh blockpull --domain dns --path /home/alank/vm/dns.qcow2 --verbose --wait
Version of package tested: 1.2.16-2ubuntu11.15.10.4
I installed the proposed libvirt packages yesterday and was able to successfully create a live external snapshot and then flatten the snapshot back into the top-level image as follows:
1. virsh snapshot-create-as dns sn1 "snapshot1" --disk-only --atomic
2. virsh blockpull --domain dns --path /home/alank/ vm/dns. qcow2 --verbose --wait
Version of package tested: 1.2.16- 2ubuntu11. 15.10.4