linux-kernel - [PATCH net-next v5 11/16] scsi: iscsi_tcp: Use sendmsg(MSG_SPLICE

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Message-ID: <20230623225513.2732256-12-dhowells@redhat.com>
Date:   Fri, 23 Jun 2023 23:55:08 +0100
From:   David Howells <dhowells@...hat.com>
To:     netdev@...r.kernel.org
Cc:     David Howells <dhowells@...hat.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        David Ahern <dsahern@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Mike Christie <michael.christie@...cle.com>,
        Lee Duncan <lduncan@...e.com>, Chris Leech <cleech@...hat.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Al Viro <viro@...iv.linux.org.uk>, open-iscsi@...glegroups.com,
        linux-scsi@...r.kernel.org, target-devel@...r.kernel.org
Subject: [PATCH net-next v5 11/16] scsi: iscsi_tcp: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage

Use sendmsg() with MSG_SPLICE_PAGES rather than sendpage.  This allows
multiple pages and multipage folios to be passed through.

Signed-off-by: David Howells <dhowells@...hat.com>
Reviewed-by: Mike Christie <michael.christie@...cle.com>
cc: Lee Duncan <lduncan@...e.com>
cc: Chris Leech <cleech@...hat.com>
cc: "James E.J. Bottomley" <jejb@...ux.ibm.com>
cc: "Martin K. Petersen" <martin.petersen@...cle.com>
cc: "David S. Miller" <davem@...emloft.net>
cc: Eric Dumazet <edumazet@...gle.com>
cc: Jakub Kicinski <kuba@...nel.org>
cc: Paolo Abeni <pabeni@...hat.com>
cc: Jens Axboe <axboe@...nel.dk>
cc: Matthew Wilcox <willy@...radead.org>
cc: Al Viro <viro@...iv.linux.org.uk>
cc: open-iscsi@...glegroups.com
cc: linux-scsi@...r.kernel.org
cc: target-devel@...r.kernel.org
cc: netdev@...r.kernel.org
---

Notes:
    ver #5)
     - Split iscsi changes into client and target patches

 drivers/scsi/iscsi_tcp.c | 26 ++++++++++----------------
 drivers/scsi/iscsi_tcp.h |  2 --
 2 files changed, 10 insertions(+), 18 deletions(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 9637d4bc2bc9..9ab8555180a3 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -301,35 +301,32 @@ static int iscsi_sw_tcp_xmit_segment(struct iscsi_tcp_conn *tcp_conn,
 
 	while (!iscsi_tcp_segment_done(tcp_conn, segment, 0, r)) {
 		struct scatterlist *sg;
+		struct msghdr msg = {};
+		struct bio_vec bv;
 		unsigned int offset, copy;
-		int flags = 0;
 
 		r = 0;
 		offset = segment->copied;
 		copy = segment->size - offset;
 
 		if (segment->total_copied + segment->size < segment->total_size)
-			flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;
+			msg.msg_flags |= MSG_MORE;
 
 		if (tcp_sw_conn->queue_recv)
-			flags |= MSG_DONTWAIT;
+			msg.msg_flags |= MSG_DONTWAIT;
 
-		/* Use sendpage if we can; else fall back to sendmsg */
 		if (!segment->data) {
+			if (!tcp_conn->iscsi_conn->datadgst_en)
+				msg.msg_flags |= MSG_SPLICE_PAGES;
 			sg = segment->sg;
 			offset += segment->sg_offset + sg->offset;
-			r = tcp_sw_conn->sendpage(sk, sg_page(sg), offset,
-						  copy, flags);
+			bvec_set_page(&bv, sg_page(sg), copy, offset);
 		} 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);
+			bvec_set_virt(&bv, segment->data + offset, copy);
 		}
+		iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bv, 1, copy);
 
+		r = sock_sendmsg(sk, &msg);
 		if (r < 0) {
 			iscsi_tcp_segment_unmap(segment);
 			return r;
@@ -746,7 +743,6 @@ iscsi_sw_tcp_conn_bind(struct iscsi_cls_session *cls_session,
 	sock_no_linger(sk);
 
 	iscsi_sw_tcp_conn_set_callbacks(conn);
-	tcp_sw_conn->sendpage = tcp_sw_conn->sock->ops->sendpage;
 	/*
 	 * set receive state machine into initial state
 	 */
@@ -777,8 +773,6 @@ static int iscsi_sw_tcp_conn_set_param(struct iscsi_cls_conn *cls_conn,
 			return -ENOTCONN;
 		}
 		iscsi_set_param(cls_conn, param, buf, buflen);
-		tcp_sw_conn->sendpage = conn->datadgst_en ?
-			sock_no_sendpage : tcp_sw_conn->sock->ops->sendpage;
 		mutex_unlock(&tcp_sw_conn->sock_lock);
 		break;
 	case ISCSI_PARAM_MAX_R2T:
diff --git a/drivers/scsi/iscsi_tcp.h b/drivers/scsi/iscsi_tcp.h
index 68e14a344904..89a6fc552f0b 100644
--- a/drivers/scsi/iscsi_tcp.h
+++ b/drivers/scsi/iscsi_tcp.h
@@ -47,8 +47,6 @@ struct iscsi_sw_tcp_conn {
 	/* MIB custom statistics */
 	uint32_t		sendpage_failures_cnt;
 	uint32_t		discontiguous_hdr_cnt;
-
-	ssize_t (*sendpage)(struct socket *, struct page *, int, size_t, int);
 };
 
 struct iscsi_sw_tcp_host {