xprtrdma: Add trace points in the client-side backchannel code paths

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index a1ca1b6..69883a9 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -365,7 +365,7 @@ rpcrdma_set_xprtdata(struct rpc_rqst *rqst, struct rpcrdma_req *req)
 }
 
 static inline struct rpcrdma_req *
-rpcr_to_rdmar(struct rpc_rqst *rqst)
+rpcr_to_rdmar(const struct rpc_rqst *rqst)
 {
 	return rqst->rq_xprtdata;
 }