Ceph » rbd

Background:
Installed openstack 2014.1.1 on Ubuntu 14.04 ( apt-get update & upgrade)
- glance with ceph
- nova with ceph
- installed without cinder
I can upload images to glance, I can also boot new instances from ceph

Then i delete and replace /usr/lib/python2.7/dist-packages/nova with nova folder from angdraug git repo (branch rbd-ephemeral-clone-stable-icehouse)
Reboot hypervisor
- Instances (backed on ceph ) are starting but cannot launch new instances

nova-compute dies with:
nova-compute¹⁸³²⁴: segfault at 125 ip 00007fc1502c27d1 sp 00007fc13effcd58 error 4 in librbd.so.1.0.0[7fc150290000+e8000]

Backtrace:
http://paste.openstack.org/show/86443/

Ceph versions:
- default Ubuntu 14.04 ceph version
- 0.80.2
- 0.80.4

Debug:
I have reproduced the issue outside nova-compute here: https://github.com/Lupul/nova-ceph-ephemeral-clone-test
(using a non-existing rbd image but with a existing image there is no problem)
- branch: test-ok never faults
- branch: test-fault always faults

librbd fails here:
/usr/lib/python2.7/dist-packages/rbd.py line 364:
ret = self.librbd.rbd_open_read_only(ioctx.io, c_char_p(name), byref(self.image), c_char_p(snapshot))