[libvirt-users] Setting RBD cache parameters for libvirt+qemu

[John Nielsen]

I am running some qemu-kvm virtual machines via libvirt using Ceph RBD as the back-end storage. Today I was testing an update to libvirt-1.0.6 on one of my hosts and discovered that it includes this change:
	[libvirt] [PATCH] Forbid use of ':' in RBD pool names
		...People are known to be abusing the lack of escaping in current libvirt to pass arbitrary args to QEMU.

I am one of those people--I have been storing colon-separated arguments in my disk source 'name' attribute to control the RBD cache settings on a per-volume basis. Under libvirt-1.0.6 such VM's refuse to start:
error: Failed to start domain foo
error: unsupported configuration: ':' not allowed in RBD source volume name 'mypool/foo:rbd_cache_size=268435456:rbd_cache_max_dirty=134217728:rbd_cache_target_dirty=33554432:rbd_cache_max_dirty_age=5'

So my question is how do I control the cache settings now?

Thanks,

JN