I've finished work on the RBD SR driver. Packaged as an RPM which makes sure the other kernel module drivers are required (otherwise the newer RBD features aren't available) and it doesn't require any rbd tooling on the dom0.
https://imirc.nl/xcpng/sm-additional-rbd-2.0-1.xcpng8.3.noarch.rpm
This needs a cephx key to have dom0 access the rbd images and a ceph mgr user/pw to manage the SR.
The driver creates a rbd namespace with the sr-uuid as it's name and the images are the vdi-uuid. so multiple sr's on the same ceph rbd pool are supported.
If leverages the xen-blkback dom0 to expose the vdi to the guest. No tapdisk, qcow2 or vhd involved. Uses native RBD snapshots, leveraging the new vdi_revert and uses GC to flatten and clean snapshots and images when required.
I'll be setting up a git repo with my sources for the kernel modules and sr driver for anyone to dive into the sources and perhaps help testing and improving this,
The next thing I'm diving into is SXM and SMAPIv3 version as I guess those are the missing parts to make this future proof.
