Commit 29dc5d06 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

ublk: kill queuing request by task_work_add 



task_work_add() is used from early ublk development stage for handling
request in batch. However, since commit 7d4a9317 ("ublk_drv: don't
forward io commands in reserve order"), we can get similar batch
processing with io_uring_cmd_complete_in_task(), and similar performance
data is observed between task_work_add() and
io_uring_cmd_complete_in_task().

Meantime we can kill one fast code path, which is actually seldom used
given it is common to build ublk driver as module.

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230519065030.351216-2-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 9a67aa52

drivers/block/ublk_drv.c

+2 −38
Original line number Diff line number Diff line
@@ -62,7 +62,6 @@ 


struct ublk_rq_data {

	struct llist_node node;

	struct callback_head work;

};



struct ublk_uring_cmd_pdu {
@@ -290,14 +289,6 @@ static int ublk_apply_params(struct ublk_device *ub) 
	return 0;

}



static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq)

{

	if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) &&

			!(ubq->flags & UBLK_F_URING_CMD_COMP_IN_TASK))

		return true;

	return false;

}



static inline bool ublk_need_get_data(const struct ublk_queue *ubq)

{

	return ubq->flags & UBLK_F_NEED_GET_DATA;
@@ -852,17 +843,6 @@ static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd, unsigned issue_flags) 
	ublk_forward_io_cmds(ubq, issue_flags);

}



static void ublk_rq_task_work_fn(struct callback_head *work)

{

	struct ublk_rq_data *data = container_of(work,

			struct ublk_rq_data, work);

	struct request *req = blk_mq_rq_from_pdu(data);

	struct ublk_queue *ubq = req->mq_hctx->driver_data;

	unsigned issue_flags = IO_URING_F_UNLOCKED;



	ublk_forward_io_cmds(ubq, issue_flags);

}



static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq)

{

	struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq);
@@ -886,10 +866,6 @@ static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq) 
	 */

	if (unlikely(io->flags & UBLK_IO_FLAG_ABORTED)) {

		ublk_abort_io_cmds(ubq);

	} else if (ublk_can_use_task_work(ubq)) {

		if (task_work_add(ubq->ubq_daemon, &data->work,

					TWA_SIGNAL_NO_IPI))

			ublk_abort_io_cmds(ubq);

	} else {

		struct io_uring_cmd *cmd = io->cmd;

		struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
@@ -961,19 +937,9 @@ static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data, 
	return 0;

}



static int ublk_init_rq(struct blk_mq_tag_set *set, struct request *req,

		unsigned int hctx_idx, unsigned int numa_node)

{

	struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);



	init_task_work(&data->work, ublk_rq_task_work_fn);

	return 0;

}



static const struct blk_mq_ops ublk_mq_ops = {

	.queue_rq       = ublk_queue_rq,

	.init_hctx	= ublk_init_hctx,

	.init_request   = ublk_init_rq,

	.timeout	= ublk_timeout,

};
@@ -1813,10 +1779,8 @@ static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd) 
	 */

	ub->dev_info.flags &= UBLK_F_ALL;



	if (!IS_BUILTIN(CONFIG_BLK_DEV_UBLK))

		ub->dev_info.flags |= UBLK_F_URING_CMD_COMP_IN_TASK;



	ub->dev_info.flags |= UBLK_F_CMD_IOCTL_ENCODE;

	ub->dev_info.flags |= UBLK_F_CMD_IOCTL_ENCODE |

		UBLK_F_URING_CMD_COMP_IN_TASK;



	/* We are not ready to support zero copy */

	ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;