Commit 40a8c17a authored by David Howells's avatar David Howells Committed by Jakub Kicinski
Browse files

ceph: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage 



Use sendmsg() and MSG_SPLICE_PAGES rather than sendpage in ceph when
transmitting data.  For the moment, this can only transmit one page at a
time because of the architecture of net/ceph/, but if
write_partial_message_data() can be given a bvec[] at a time by the
iteration code, this would allow pages to be sent in a batch.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Xiubo Li <xiubli@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Link: https://lore.kernel.org/r/20230623225513.2732256-4-dhowells@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent c729ed6f

net/ceph/messenger_v1.c

+20 −40
Original line number Diff line number Diff line
@@ -74,37 +74,6 @@ static int ceph_tcp_sendmsg(struct socket *sock, struct kvec *iov, 
	return r;

}



/*

 * @more: either or both of MSG_MORE and MSG_SENDPAGE_NOTLAST

 */

static int ceph_tcp_sendpage(struct socket *sock, struct page *page,

			     int offset, size_t size, int more)

{

	ssize_t (*sendpage)(struct socket *sock, struct page *page,

			    int offset, size_t size, int flags);

	int flags = MSG_DONTWAIT | MSG_NOSIGNAL | more;

	int ret;



	/*

	 * sendpage cannot properly handle pages with page_count == 0,

	 * we need to fall back to sendmsg if that's the case.

	 *

	 * Same goes for slab pages: skb_can_coalesce() allows

	 * coalescing neighboring slab objects into a single frag which

	 * triggers one of hardened usercopy checks.

	 */

	if (sendpage_ok(page))

		sendpage = sock->ops->sendpage;

	else

		sendpage = sock_no_sendpage;



	ret = sendpage(sock, page, offset, size, flags);

	if (ret == -EAGAIN)

		ret = 0;



	return ret;

}



static void con_out_kvec_reset(struct ceph_connection *con)

{

	BUG_ON(con->v1.out_skip);
@@ -464,7 +433,6 @@ static int write_partial_message_data(struct ceph_connection *con) 
	struct ceph_msg *msg = con->out_msg;

	struct ceph_msg_data_cursor *cursor = &msg->cursor;

	bool do_datacrc = !ceph_test_opt(from_msgr(con->msgr), NOCRC);

	int more = MSG_MORE | MSG_SENDPAGE_NOTLAST;

	u32 crc;



	dout("%s %p msg %p\n", __func__, con, msg);
@@ -482,6 +450,10 @@ static int write_partial_message_data(struct ceph_connection *con) 
	 */

	crc = do_datacrc ? le32_to_cpu(msg->footer.data_crc) : 0;

	while (cursor->total_resid) {

		struct bio_vec bvec;

		struct msghdr msghdr = {

			.msg_flags = MSG_SPLICE_PAGES,

		};

		struct page *page;

		size_t page_offset;

		size_t length;
@@ -493,10 +465,13 @@ static int write_partial_message_data(struct ceph_connection *con) 
		}



		page = ceph_msg_data_next(cursor, &page_offset, &length);

		if (length == cursor->total_resid)

			more = MSG_MORE;

		ret = ceph_tcp_sendpage(con->sock, page, page_offset, length,

					more);

		if (length != cursor->total_resid)

			msghdr.msg_flags |= MSG_MORE;



		bvec_set_page(&bvec, page, length, page_offset);

		iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, length);



		ret = sock_sendmsg(con->sock, &msghdr);

		if (ret <= 0) {

			if (do_datacrc)

				msg->footer.data_crc = cpu_to_le32(crc);
@@ -526,7 +501,10 @@ static int write_partial_message_data(struct ceph_connection *con) 
 */

static int write_partial_skip(struct ceph_connection *con)

{

	int more = MSG_MORE | MSG_SENDPAGE_NOTLAST;

	struct bio_vec bvec;

	struct msghdr msghdr = {

		.msg_flags = MSG_SPLICE_PAGES | MSG_MORE,

	};

	int ret;



	dout("%s %p %d left\n", __func__, con, con->v1.out_skip);
@@ -534,9 +512,11 @@ static int write_partial_skip(struct ceph_connection *con) 
		size_t size = min(con->v1.out_skip, (int)PAGE_SIZE);



		if (size == con->v1.out_skip)

			more = MSG_MORE;

		ret = ceph_tcp_sendpage(con->sock, ceph_zero_page, 0, size,

					more);

			msghdr.msg_flags &= ~MSG_MORE;

		bvec_set_page(&bvec, ZERO_PAGE(0), size, 0);

		iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, size);



		ret = sock_sendmsg(con->sock, &msghdr);

		if (ret <= 0)

			goto out;

		con->v1.out_skip -= ret;