libvirt users - May 2016 - [Ceph] blockInfo cannot work with network type disk

Hi devs & users,

The Telemetry service of OpenStack, project code name Ceilometer, is using
libvirt.domain.blockInfo() to get disk's physical, allocation and capacity
information [1]. However, when disk is network type with protocol ceph, the
blockInfo() always fail with: libvirtError: internal error: missing storage
backend for network files using rbd protocol. [2]

After reading some libvirt code, I think it might due to blockInfo() always
assume disk is file backend [3], and file backend doesn't support network
type [4].

I want to know if such limitation is by design?

   - If yes, then how should I get the network type disk's physical,
   allocation and capacity info?
   - If not, is there any plan to implement it?


Thanks!

[1]
https://github.com/openstack/ceilometer/blob/stable/mitaka/ceilometer/compute/virt/libvirt/inspector.py#L215
[2] https://bugs.launchpad.net/ceilometer/+bug/1457440
[3]
https://github.com/libvirt/libvirt/blob/d6c25c34ef682a69f73f6ec200129e61b2932088/src/qemu/qemu_driver.c#L11727
[4]
https://github.com/libvirt/libvirt/blob/d6c25c34ef682a69f73f6ec200129e61b2932088/src/storage/storage_backend.c#L142