xprtrdma: Add ro_unmap_sync method for all-physical registration

physical's ro_unmap is synchronous already. The new ro_unmap_sync
method just has to DMA unmap all MRs associated with the RPC
request.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/physical_ops.c

@@ -83,6 +83,18 @@ physical_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
 	return 1;
 }
 
+/* DMA unmap all memory regions that were mapped for "req".
+ */
+static void
+physical_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
+{
+	struct ib_device *device = r_xprt->rx_ia.ri_device;
+	unsigned int i;
+
+	for (i = 0; req->rl_nchunks; --req->rl_nchunks)
+		rpcrdma_unmap_one(device, &req->rl_segments[i++]);
+}
+
 static void
 physical_op_destroy(struct rpcrdma_buffer *buf)
 {
@@ -90,6 +102,7 @@ physical_op_destroy(struct rpcrdma_buffer *buf)
 
 const struct rpcrdma_memreg_ops rpcrdma_physical_memreg_ops = {
 	.ro_map				= physical_op_map,
+	.ro_unmap_sync			= physical_op_unmap_sync,
 	.ro_unmap			= physical_op_unmap,
 	.ro_open			= physical_op_open,
 	.ro_maxpages			= physical_op_maxpages,