Fengguang Wu reminded me that there were outstanding sparse reports
in the ceph and rbd code. This patch fixes these problems in rbd
that lead to those reports:
- Convert functions that are never referenced externally to have
static scope.
- Add a lockdep annotation to rbd_request_fn(), because it
releases a lock before acquiring it again.
This partially resolves:
http://tracker.ceph.com/issues/4184