[PATCH 06/12] scsi: iscsi_tcp: Use sendpage for the PDU header

[Mike Christie <michael.christie@xxxxxxxxxx>]

This has us use zero copy the PDU header.

Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
 drivers/scsi/iscsi_tcp.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 261599938fc9..3bdefc4b6b17 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -306,7 +306,7 @@ static int iscsi_sw_tcp_xmit_segment(struct iscsi_tcp_conn *tcp_conn,
 		copy = segment->size - offset;
 
 		if (segment->total_copied + segment->size < segment->total_size)
-			flags |= MSG_MORE;
+			flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;
 
 		/* Use sendpage if we can; else fall back to sendmsg */
 		if (!segment->data) {
@@ -315,13 +315,27 @@ static int iscsi_sw_tcp_xmit_segment(struct iscsi_tcp_conn *tcp_conn,
 			r = tcp_sw_conn->sendpage(sk, sg_page(sg), offset,
 						  copy, flags);
 		} else {
-			struct msghdr msg = { .msg_flags = flags };
-			struct kvec iov = {
-				.iov_base = segment->data + offset,
-				.iov_len = copy
-			};
-
-			r = kernel_sendmsg(sk, &msg, &iov, 1, copy);
+			void *data = segment->data + offset;
+
+			/*
+			 * Make sure it's ok to send the header using zero
+			 * copy. The case where the sg page can't be zero
+			 * copied will also go down the sendmsg path.
+			 */
+			if (sendpage_ok(data)) {
+				r = tcp_sw_conn->sendpage(sk,
+						virt_to_page(data),
+						offset_in_page(data), copy,
+						flags);
+			} else {
+				struct msghdr msg = { .msg_flags = flags };
+				struct kvec iov = {
+					.iov_base = data,
+					.iov_len = copy,
+				};
+
+				r = kernel_sendmsg(sk, &msg, &iov, 1, copy);
+			}
 		}
 
 		if (r < 0) {
-- 
2.25.1