Commit 572efade authored by David Howells's avatar David Howells Committed by Jakub Kicinski
Browse files

rds: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage 



When transmitting data, call down into TCP using a single sendmsg with
MSG_SPLICE_PAGES to indicate that content should be spliced.

To make this work, the data is assembled in a bio_vec array and attached to
a BVEC-type iterator.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Santosh Shilimkar <santosh.shilimkar@oracle.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: rds-devel@oss.oracle.com
Link: https://lore.kernel.org/r/20230623225513.2732256-6-dhowells@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent fa094cca

net/rds/tcp_send.c

+12 −11
Original line number Diff line number Diff line
@@ -72,9 +72,10 @@ int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm, 
{

	struct rds_conn_path *cp = rm->m_inc.i_conn_path;

	struct rds_tcp_connection *tc = cp->cp_transport_data;

	struct msghdr msg = {};

	struct bio_vec bvec;

	int done = 0;

	int ret = 0;

	int more;



	if (hdr_off == 0) {

		/*
@@ -111,15 +112,17 @@ int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm, 
			goto out;

	}



	more = rm->data.op_nents > 1 ? (MSG_MORE | MSG_SENDPAGE_NOTLAST) : 0;

	while (sg < rm->data.op_nents) {

		int flags = MSG_DONTWAIT | MSG_NOSIGNAL | more;

		msg.msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT | MSG_NOSIGNAL;

		if (sg + 1 < rm->data.op_nents)

			msg.msg_flags |= MSG_MORE;



		ret = tc->t_sock->ops->sendpage(tc->t_sock,

						sg_page(&rm->data.op_sg[sg]),

						rm->data.op_sg[sg].offset + off,

		bvec_set_page(&bvec, sg_page(&rm->data.op_sg[sg]),

			      rm->data.op_sg[sg].length - off,

						flags);

			      rm->data.op_sg[sg].offset + off);

		iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1,

			      rm->data.op_sg[sg].length - off);

		ret = sock_sendmsg(tc->t_sock, &msg);

		rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->data.op_sg[sg]),

			 rm->data.op_sg[sg].offset + off, rm->data.op_sg[sg].length - off,

			 ret);
@@ -132,8 +135,6 @@ int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm, 
			off = 0;

			sg++;

		}

		if (sg == rm->data.op_nents - 1)

			more = 0;

	}



out: