[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 <dhow...@redhat.com>
cc: Mike Christie <michael....@oracle.com>
cc: Maurizio Lombardi <mlom...@redhat.com>
cc: "James E.J. Bottomley" <je...@linux.ibm.com>
cc: "Martin K. Petersen" <martin....@oracle.com>
cc: "David S. Miller" <da...@davemloft.net>
cc: Eric Dumazet <edum...@google.com>
cc: Jakub Kicinski <ku...@kernel.org>
cc: Paolo Abeni <pab...@redhat.com>
cc: Jens Axboe <ax...@kernel.dk>
cc: Matthew Wilcox <wi...@infradead.org>
cc: Al Viro <vi...@zeniv.linux.org.uk>
cc: open-...@googlegroups.com
cc: linux...@vger.kernel.org
cc: target...@vger.kernel.org
cc: net...@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;
}