What were you trying to do that didn't work?

If a VM is migrated while paused and not unpaused od the destination, qemu doesn't re-activate the disk backends. This can lean to failures or even qemu abort() when attempting to run a blockjob.

Observed behaviour:

• error: internal error: unable to execute QEMU command 'block-commit': Block node is read-only
• error: internal error: unable to execute QEMU command 'blockdev-mirror': Inactive 'libvirt-1-storage' can't be a backing child of active '#block089'
• possibly assertion failure and abort() in qemu
• some read-only job such as blockcopy succeed without recent upstream fixes but fail thereafter

Libvirt will need to use the new interface in qemu to re-activate the nodes after migration.