[PATCH net-next v5 07/16] nvme-tcp: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage
From: David Howells <dhowells@redhat.com>
Date: 2023-06-23 22:57:06
Also in:
linux-mm, linux-nvme, lkml
Subsystem:
nvm express driver, the rest · Maintainers:
Keith Busch, Jens Axboe, Christoph Hellwig, Sagi Grimberg, Linus Torvalds
When transmitting data, call down into TCP using a sendmsg with
MSG_SPLICE_PAGES instead of sendpage.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Sagi Grimberg <sagi@grimberg.me>
Acked-by: Willem de Bruijn <willemb@google.com>
cc: Keith Busch <kbusch@kernel.org>
cc: Jens Axboe <axboe@fb.com>
cc: Christoph Hellwig <hch@lst.de>
cc: Chaitanya Kulkarni <kch@nvidia.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-nvme@lists.infradead.org
cc: netdev@vger.kernel.org
---
Notes:
ver #4)
- Cancel MSG_SPLICE_PAGES if the page being sent fails sendpage_ok().
ver #3)
- Split nvme/host from nvme/target changes.
ver #2)
- Wrap lines at 80.
drivers/nvme/host/tcp.c | 49 +++++++++++++++++++++++------------------
1 file changed, 27 insertions(+), 22 deletions(-)
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index bf0230442d57..47ae17f16c05 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c@@ -997,25 +997,28 @@ static int nvme_tcp_try_send_data(struct nvme_tcp_request *req) u32 h2cdata_left = req->h2cdata_left; while (true) { + struct bio_vec bvec; + struct msghdr msg = { + .msg_flags = MSG_DONTWAIT | MSG_SPLICE_PAGES, + }; struct page *page = nvme_tcp_req_cur_page(req); size_t offset = nvme_tcp_req_cur_offset(req); size_t len = nvme_tcp_req_cur_length(req); bool last = nvme_tcp_pdu_last_send(req, len); int req_data_sent = req->data_sent; - int ret, flags = MSG_DONTWAIT; + int ret; if (last && !queue->data_digest && !nvme_tcp_queue_more(queue)) - flags |= MSG_EOR; + msg.msg_flags |= MSG_EOR; else - flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST; + msg.msg_flags |= MSG_MORE; - if (sendpage_ok(page)) { - ret = kernel_sendpage(queue->sock, page, offset, len, - flags); - } else { - ret = sock_no_sendpage(queue->sock, page, offset, len, - flags); - } + if (!sendpage_ok(page)) + msg.msg_flags &= ~MSG_SPLICE_PAGES, + + bvec_set_page(&bvec, page, len, offset); + iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, len); + ret = sock_sendmsg(queue->sock, &msg); if (ret <= 0) return ret;
@@ -1054,22 +1057,24 @@ static int nvme_tcp_try_send_cmd_pdu(struct nvme_tcp_request *req) { struct nvme_tcp_queue *queue = req->queue; struct nvme_tcp_cmd_pdu *pdu = nvme_tcp_req_cmd_pdu(req); + struct bio_vec bvec; + struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_SPLICE_PAGES, }; bool inline_data = nvme_tcp_has_inline_data(req); u8 hdgst = nvme_tcp_hdgst_len(queue); int len = sizeof(*pdu) + hdgst - req->offset; - int flags = MSG_DONTWAIT; int ret; if (inline_data || nvme_tcp_queue_more(queue)) - flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST; + msg.msg_flags |= MSG_MORE; else - flags |= MSG_EOR; + msg.msg_flags |= MSG_EOR; if (queue->hdr_digest && !req->offset) nvme_tcp_hdgst(queue->snd_hash, pdu, sizeof(*pdu)); - ret = kernel_sendpage(queue->sock, virt_to_page(pdu), - offset_in_page(pdu) + req->offset, len, flags); + bvec_set_virt(&bvec, (void *)pdu + req->offset, len); + iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, len); + ret = sock_sendmsg(queue->sock, &msg); if (unlikely(ret <= 0)) return ret;
@@ -1093,6 +1098,8 @@ static int nvme_tcp_try_send_data_pdu(struct nvme_tcp_request *req) { struct nvme_tcp_queue *queue = req->queue; struct nvme_tcp_data_pdu *pdu = nvme_tcp_req_data_pdu(req); + struct bio_vec bvec; + struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_MORE, }; u8 hdgst = nvme_tcp_hdgst_len(queue); int len = sizeof(*pdu) - req->offset + hdgst; int ret;
@@ -1101,13 +1108,11 @@ static int nvme_tcp_try_send_data_pdu(struct nvme_tcp_request *req) nvme_tcp_hdgst(queue->snd_hash, pdu, sizeof(*pdu)); if (!req->h2cdata_left) - ret = kernel_sendpage(queue->sock, virt_to_page(pdu), - offset_in_page(pdu) + req->offset, len, - MSG_DONTWAIT | MSG_MORE | MSG_SENDPAGE_NOTLAST); - else - ret = sock_no_sendpage(queue->sock, virt_to_page(pdu), - offset_in_page(pdu) + req->offset, len, - MSG_DONTWAIT | MSG_MORE); + msg.msg_flags |= MSG_SPLICE_PAGES; + + bvec_set_virt(&bvec, (void *)pdu + req->offset, len); + iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, len); + ret = sock_sendmsg(queue->sock, &msg); if (unlikely(ret <= 0)) return ret;