libceph: init osd->o_node in create_osd()

The red-black node node in the ceph osd structure is not initialized
in create_osd().  Because this node can be the subject of a
RB_EMPTY_NODE() call later on, we should ensure the node is
initialized properly for that.  Add a call to RB_CLEAR_NODE()
initialize it.
Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NSage Weil <sage@inktank.com>

net/ceph/osd_client.c

@@ -642,6 +642,7 @@ static struct ceph_osd *create_osd(struct ceph_osd_client *osdc, int onum)
 	atomic_set(&osd->o_ref, 1);
 	osd->o_osdc = osdc;
 	osd->o_osd = onum;
+	RB_CLEAR_NODE(&osd->o_node);
 	INIT_LIST_HEAD(&osd->o_requests);
 	INIT_LIST_HEAD(&osd->o_linger_requests);
 	INIT_LIST_HEAD(&osd->o_osd_lru);