svcrdma: Fence LOCAL_INV work requests

Fencing forces the invalidate to only happen after all prior send
work requests have been completed.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Reported by : Devesh Sharma <Devesh.Sharma@Emulex.Com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

@@ -338,7 +338,7 @@ static int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt,
 		memset(&inv_wr, 0, sizeof(inv_wr));
 		inv_wr.wr_id = (unsigned long)ctxt;
 		inv_wr.opcode = IB_WR_LOCAL_INV;
-		inv_wr.send_flags = IB_SEND_SIGNALED;
+		inv_wr.send_flags = IB_SEND_SIGNALED | IB_SEND_FENCE;
 		inv_wr.ex.invalidate_rkey = frmr->mr->lkey;
 	}
 	ctxt->wr_op = read_wr.opcode;