xprtrdma: Chain Send to FastReg WRs

With FRWR, the client transport can perform memory registration and
post a Send with just a single ib_post_send.

This reduces contention between the send_request path and the Send
Completion handlers, and reduces the overhead of registering a chunk
that has multiple segments.

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 29ea0b4..3d3b423 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -472,6 +472,8 @@ struct rpcrdma_memreg_ops {
 			(*ro_map)(struct rpcrdma_xprt *,
 				  struct rpcrdma_mr_seg *, int, bool,
 				  struct rpcrdma_mr **);
+	int		(*ro_send)(struct rpcrdma_ia *ia,
+				   struct rpcrdma_req *req);
 	void		(*ro_reminv)(struct rpcrdma_rep *rep,
 				     struct list_head *mrs);
 	void		(*ro_unmap_sync)(struct rpcrdma_xprt *,