[PATCH net-next v5 11/16] scsi: iscsi_tcp: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage

[PATCH net-next v5 11/16] scsi: iscsi_tcp: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage

[David Howells]

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@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
cc: Lee Duncan <lduncan@suse.com>
cc: Chris Leech <cleech@redhat.com>
cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
cc: "Martin K. Petersen" <martin.petersen@oracle.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: open-iscsi@googlegroups.com
cc: linux-scsi@vger.kernel.org
cc: target-devel@vger.kernel.org
cc: netdev@vger.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 {

Re: [PATCH net-next v5 11/16] scsi: iscsi_tcp: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage

[Chris Leech]

On Fri, Jun 23, 2023 at 11:55:08PM +0100, David Howells wrote:
> 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@redhat.com>
> Reviewed-by: Mike Christie <michael.christie@oracle.com>
> cc: Lee Duncan <lduncan@suse.com>
> cc: Chris Leech <cleech@redhat.com>
> cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
> cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> cc: "David S. Miller" <davem@davemloft.net>
> cc: Eric Dumazet <edumazet@google.com>
> cc: Jakub Kicinski <kuba@kernel.org>
> cc: Paolo Abeni <pabeni@redhat.com>
> cc: Jens Axboe <axboe@kernel.dk>
> cc: Matthew Wilcox <willy@infradead.org>
> cc: Al Viro <viro@zeniv.linux.org.uk>
> cc: open-iscsi@googlegroups.com
> cc: linux-scsi@vger.kernel.org
> cc: target-devel@vger.kernel.org
> cc: netdev@vger.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(-)

This seems good to me.

Reviewed-by: Chris Leech <cleech@redhat.com>
 
> 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 {
> 

[PATCH net-next v5 12/16] scsi: target: iscsi: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage

[David Howells]

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

TODO: iscsit_fe_sendpage_sg() should perhaps set up a bio_vec array for the
entire set of pages it's going to transfer plus two for the header and
trailer and page fragments to hold the header and trailer - and then call
sendmsg once for the entire message.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Mike Christie <michael.christie@oracle.com>
cc: Maurizio Lombardi <mlombard@redhat.com>
cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
cc: "Martin K. Petersen" <martin.petersen@oracle.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: open-iscsi@googlegroups.com
cc: linux-scsi@vger.kernel.org
cc: target-devel@vger.kernel.org
cc: netdev@vger.kernel.org
---

Notes:
    ver #5)
     - Split iscsi changes into client and target patches
    
    ver #2)
     - Wrap lines at 80.

 drivers/target/iscsi/iscsi_target_util.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index b14835fcb033..6231fa4ef5c6 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -1129,6 +1129,8 @@ int iscsit_fe_sendpage_sg(
 	struct iscsit_conn *conn)
 {
 	struct scatterlist *sg = cmd->first_data_sg;
+	struct bio_vec bvec;
+	struct msghdr msghdr = { .msg_flags = MSG_SPLICE_PAGES,	};
 	struct kvec iov;
 	u32 tx_hdr_size, data_len;
 	u32 offset = cmd->first_data_sg_off;
@@ -1172,17 +1174,18 @@ int iscsit_fe_sendpage_sg(
 		u32 space = (sg->length - offset);
 		u32 sub_len = min_t(u32, data_len, space);
 send_pg:
-		tx_sent = conn->sock->ops->sendpage(conn->sock,
-					sg_page(sg), sg->offset + offset, sub_len, 0);
+		bvec_set_page(&bvec, sg_page(sg), sub_len, sg->offset + offset);
+		iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, sub_len);
+
+		tx_sent = conn->sock->ops->sendmsg(conn->sock, &msghdr,
+						   sub_len);
 		if (tx_sent != sub_len) {
 			if (tx_sent == -EAGAIN) {
-				pr_err("tcp_sendpage() returned"
-						" -EAGAIN\n");
+				pr_err("sendmsg/splice returned -EAGAIN\n");
 				goto send_pg;
 			}
 
-			pr_err("tcp_sendpage() failure: %d\n",
-					tx_sent);
+			pr_err("sendmsg/splice failure: %d\n", tx_sent);
 			return -1;
 		}