nvmet-tcp: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage

When transmitting data, call down into TCP using a single sendmsg with
MSG_SPLICE_PAGES to indicate that content should be spliced rather than
copied instead of calling 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: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-nvme@lists.infradead.org
Link: https://lore.kernel.org/r/20230623225513.2732256-9-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index ed98df7..868aa4d 100644 (file)
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -576,13 +576,17 @@ static void nvmet_tcp_execute_request(struct nvmet_tcp_cmd *cmd)
 
 static int nvmet_try_send_data_pdu(struct nvmet_tcp_cmd *cmd)
 {
+       struct msghdr msg = {
+               .msg_flags = MSG_DONTWAIT | MSG_MORE | MSG_SPLICE_PAGES,
+       };
+       struct bio_vec bvec;
        u8 hdgst = nvmet_tcp_hdgst_len(cmd->queue);
        int left = sizeof(*cmd->data_pdu) - cmd->offset + hdgst;
        int ret;
 
-       ret = kernel_sendpage(cmd->queue->sock, virt_to_page(cmd->data_pdu),
-                       offset_in_page(cmd->data_pdu) + cmd->offset,
-                       left, MSG_DONTWAIT | MSG_MORE | MSG_SENDPAGE_NOTLAST);
+       bvec_set_virt(&bvec, (void *)cmd->data_pdu + cmd->offset, left);
+       iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, left);
+       ret = sock_sendmsg(cmd->queue->sock, &msg);
        if (ret <= 0)
                return ret;
 
@@ -603,17 +607,21 @@ static int nvmet_try_send_data(struct nvmet_tcp_cmd *cmd, bool last_in_batch)
        int ret;
 
        while (cmd->cur_sg) {
+               struct msghdr msg = {
+                       .msg_flags = MSG_DONTWAIT | MSG_SPLICE_PAGES,
+               };
                struct page *page = sg_page(cmd->cur_sg);
+               struct bio_vec bvec;
                u32 left = cmd->cur_sg->length - cmd->offset;
-               int flags = MSG_DONTWAIT;
 
                if ((!last_in_batch && cmd->queue->send_list_len) ||
                    cmd->wbytes_done + left < cmd->req.transfer_len ||
                    queue->data_digest || !queue->nvme_sq.sqhd_disabled)
-                       flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;
+                       msg.msg_flags |= MSG_MORE;
 
-               ret = kernel_sendpage(cmd->queue->sock, page, cmd->offset,
-                                       left, flags);
+               bvec_set_page(&bvec, page, left, cmd->offset);
+               iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, left);
+               ret = sock_sendmsg(cmd->queue->sock, &msg);
                if (ret <= 0)
                        return ret;
 
@@ -649,18 +657,20 @@ static int nvmet_try_send_data(struct nvmet_tcp_cmd *cmd, bool last_in_batch)
 static int nvmet_try_send_response(struct nvmet_tcp_cmd *cmd,
                bool last_in_batch)
 {
+       struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_SPLICE_PAGES, };
+       struct bio_vec bvec;
        u8 hdgst = nvmet_tcp_hdgst_len(cmd->queue);
        int left = sizeof(*cmd->rsp_pdu) - cmd->offset + hdgst;
-       int flags = MSG_DONTWAIT;
        int ret;
 
        if (!last_in_batch && cmd->queue->send_list_len)
-               flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;
+               msg.msg_flags |= MSG_MORE;
        else
-               flags |= MSG_EOR;
+               msg.msg_flags |= MSG_EOR;
 
-       ret = kernel_sendpage(cmd->queue->sock, virt_to_page(cmd->rsp_pdu),
-               offset_in_page(cmd->rsp_pdu) + cmd->offset, left, flags);
+       bvec_set_virt(&bvec, (void *)cmd->rsp_pdu + cmd->offset, left);
+       iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, left);
+       ret = sock_sendmsg(cmd->queue->sock, &msg);
        if (ret <= 0)
                return ret;
        cmd->offset += ret;
@@ -677,18 +687,20 @@ static int nvmet_try_send_response(struct nvmet_tcp_cmd *cmd,
 
 static int nvmet_try_send_r2t(struct nvmet_tcp_cmd *cmd, bool last_in_batch)
 {
+       struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_SPLICE_PAGES, };
+       struct bio_vec bvec;
        u8 hdgst = nvmet_tcp_hdgst_len(cmd->queue);
        int left = sizeof(*cmd->r2t_pdu) - cmd->offset + hdgst;
-       int flags = MSG_DONTWAIT;
        int ret;
 
        if (!last_in_batch && cmd->queue->send_list_len)
-               flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;
+               msg.msg_flags |= MSG_MORE;
        else
-               flags |= MSG_EOR;
+               msg.msg_flags |= MSG_EOR;
 
-       ret = kernel_sendpage(cmd->queue->sock, virt_to_page(cmd->r2t_pdu),
-               offset_in_page(cmd->r2t_pdu) + cmd->offset, left, flags);
+       bvec_set_virt(&bvec, (void *)cmd->r2t_pdu + cmd->offset, left);
+       iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, left);
+       ret = sock_sendmsg(cmd->queue->sock, &msg);
        if (ret <= 0)
                return ret;
        cmd->offset += ret;