[libvirt] Proposal for snapshotting functions of volumes

[Wido den Hollander]

Hi,

Currently libvirt is lacking support for snapshotting volumes through
the storage pool mechanism.

I want to add this to libvirt, but since the internals and the API
design ideas of libvirt are not fully known to me I wanted to put this
up for a basic review first.

This patch can also be viewed on Github: https://github.com/wido/libvirt/commit/4483ab247f607250c5b3314d0a19509ef2512852

My main questions are:
* Is this something we would like to see in libvirt?
* If so, am I on the right track?
* If so, what API calls should be different?

The steps I want to take:
1. Add the new API calls
2. Add support to the RBD backend
3. Add support to virsh
4. Add support to the Java bindings

The Apache CloudStack project uses libvirt intensively and I want to
add as much support to libvirt as we need so that we don't do stuff
inside CloudStack where libvirt might be a lot better place to do
it.

Any comments are very much appreciated before I start spending hours
of my time on this :)

Wido