From: Sagi Grimberg sagi@grimberg.me
commit 98fd5c723730f560e5bea919a64ac5b83d45eb72 upstream.
When we send PDU data, we want to optimize the tcp stack operation if we have more data to send. So when we set MSG_MORE when: - We have more fragments coming in the batch, or - We have a more data to send in this PDU - We don't have a data digest trailer - We optimize with the SUCCESS flag and omit the NVMe completion (used if sq_head pointer update is disabled)
This addresses a regression in QD=1 with SUCCESS flag optimization as we unconditionally set MSG_MORE when we didn't actually have more data to send.
Fixes: 70583295388a ("nvmet-tcp: implement C2HData SUCCESS optimization") Reported-by: Mark Wunderlich mark.wunderlich@intel.com Tested-by: Mark Wunderlich mark.wunderlich@intel.com Signed-off-by: Sagi Grimberg sagi@grimberg.me Signed-off-by: Keith Busch kbusch@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/nvme/target/tcp.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
--- a/drivers/nvme/target/tcp.c +++ b/drivers/nvme/target/tcp.c @@ -515,7 +515,7 @@ static int nvmet_try_send_data_pdu(struc return 1; }
-static int nvmet_try_send_data(struct nvmet_tcp_cmd *cmd) +static int nvmet_try_send_data(struct nvmet_tcp_cmd *cmd, bool last_in_batch) { struct nvmet_tcp_queue *queue = cmd->queue; int ret; @@ -523,9 +523,15 @@ static int nvmet_try_send_data(struct nv while (cmd->cur_sg) { struct page *page = sg_page(cmd->cur_sg); 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;
ret = kernel_sendpage(cmd->queue->sock, page, cmd->offset, - left, MSG_DONTWAIT | MSG_MORE); + left, flags); if (ret <= 0) return ret;
@@ -660,7 +666,7 @@ static int nvmet_tcp_try_send_one(struct }
if (cmd->state == NVMET_TCP_SEND_DATA) { - ret = nvmet_try_send_data(cmd); + ret = nvmet_try_send_data(cmd, last_in_batch); if (ret <= 0) goto done_send; }