Merge tag 'ceph-for-4.14-rc2' of git://github.com/ceph/ceph-client

Pull ceph fixes from Ilya Dryomov:
 "Two small but important fixes: RADOS semantic change in upcoming v12.2.1
  release and a rare NULL dereference in create_session_open_msg()"

* tag 'ceph-for-4.14-rc2' of git://github.com/ceph/ceph-client:
  ceph: avoid panic in create_session_open_msg() if utsname() returns NULL
  libceph: don't allow bidirectional swap of pg-upmap-items