svcrdma: Modify the RPC reply path to use FRMR when available

Use FRMR to map local RPC reply data. This allows RDMA_WRITE to send reply
data using a single WR. The FRMR is invalidated by linking the LOCAL_INV WR
to the RDMA_SEND message used to complete the reply.
Signed-off-by: Tom Tucker <tom@opengridcomputing.com>

net/sunrpc/xprtrdma/svc_rdma_transport.c

@@ -335,6 +335,8 @@ static void process_context(struct svcxprt_rdma *xprt,
 
 	switch (ctxt->wr_op) {
 	case IB_WR_SEND:
+		if (test_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags))
+			svc_rdma_put_frmr(xprt, ctxt->frmr);
 		svc_rdma_put_context(ctxt, 1);
 		break;