[RFC PATCH 20/28] iscsi: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage
From: David Howells <dhowells@redhat.com>
Date: 2023-03-16 15:30:37
Also in:
linux-fsdevel, linux-mm, linux-scsi, lkml, target-devel
Subsystem:
scsi target subsystem, the rest · Maintainers:
"Martin K. Petersen", Linus Torvalds
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 use zcopy_alloc() to allocate the header and trailer - and then call sendmsg once for the entire message. Signed-off-by: David Howells <dhowells@redhat.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: linux-scsi@vger.kernel.org cc: target-devel@vger.kernel.org cc: netdev@vger.kernel.org --- drivers/target/iscsi/iscsi_target_util.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 26dc8ed3045b..c7d58e41ac3b 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c@@ -1078,6 +1078,8 @@ 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;
@@ -1121,17 +1123,17 @@ 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; }