libceph: register request before unregister linger

In kick_requests(), we need to register the request before we
unregister the linger request.  Otherwise the unregister will
reset the request's osd pointer to NULL.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 7cd0a7f..780caf6 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -1328,8 +1328,8 @@
 
 		dout("kicking lingering %p tid %llu osd%d\n", req, req->r_tid,
 		     req->r_osd ? req->r_osd->o_osd : -1);
-		__unregister_linger_request(osdc, req);
 		__register_request(osdc, req);
+		__unregister_linger_request(osdc, req);
 	}
 	mutex_unlock(&osdc->request_mutex);