Ceph » rbd

When attempting to boot a new QEMU VM, after an upgrade from 0.94.3 to 0.94.4:

librbd/LibrbdWriteback.cc: In function 'virtual ceph_tid_t librbd::LibrbdWriteback::write(const object_t&, const object_locator_t&, uint64_t, uint64_t, const SnapContext&, const bufferlist&, utime_t, uint64_t, __u32, Context*)' thread 7f0393fff700 time 2015-10-21 13:01:16.494974
librbd/LibrbdWriteback.cc: 160: FAILED assert(m_ictx->owner_lock.is_locked())
ceph version 0.94.4 (95292699291242794510b39ffde3f4df67898d3a)
1: (()+0x17258b) [0x7f03b896258b]
2: (()+0xa9573) [0x7f03b8899573]
3: (()+0x3a90ca) [0x7f03b8b990ca]
4: (()+0x3b583d) [0x7f03b8ba583d]
5: (()+0x7212c) [0x7f03b886212c]
6: (()+0x9590f) [0x7f03b888590f]
7: (()+0x969a3) [0x7f03b88869a3]
8: (()+0x4782a) [0x7f03b883782a]
9: (()+0x56599) [0x7f03b8846599]
10: (()+0x7284e) [0x7f03b886284e]
11: (()+0x162b7e) [0x7f03b8952b7e]
12: (()+0x163c10) [0x7f03b8953c10]
13: (()+0x8182) [0x7f03b1e3f182]
14: (clone()+0x6d) [0x7f03b1b6c47d]
NOTE: a copy of the executable, or `objdump -rdS <executable>` is needed to interpret this.
terminate called after throwing an instance of 'ceph::FailedAssertion'

Reverting to 0.94.3 fixes the issue. Weirdly, the problem only seems to occur on the first boot attempt - subsequent attempts work correctly.