#7317 ENOSPC and OSD epoch barrier handling


Related:
https://github.com/ceph/ceph-qa-suite/pull/225
https://github.com/ceph/ceph-client/pull/7
This is awfully specific data for a generic "status" command. Shouldn't that include...more status?
Or it can be a specific epoch_barrier check, but if I dump a status I'd want to see stuff like the size of the cache, health of MDS sessions, etc.