nvme: optimise io_uring passthrough completion

Use IOU_F_TWQ_LAZY_WAKE via iou_cmd_exec_in_task_lazy() for passthrough
commands completion. It further delays the execution of task_work for
DEFER_TASKRUN until there are enough of task_work items queued to meet
the waiting criteria, which reduces the number of wake ups we issue.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ecdfacd0967a22d88b7779e2efd09e040825d0f8.1684154817.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/ioctl.c

@@ -521,7 +521,7 @@ static enum rq_end_io_ret nvme_uring_cmd_end_io(struct request *req,
 	if (cookie != NULL && blk_rq_is_poll(req))
 		nvme_uring_task_cb(ioucmd, IO_URING_F_UNLOCKED);
 	else
-		io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_cb);
+		io_uring_cmd_do_in_task_lazy(ioucmd, nvme_uring_task_cb);
 
 	return RQ_END_IO_FREE;
 }
@@ -543,7 +543,7 @@ static enum rq_end_io_ret nvme_uring_cmd_end_io_meta(struct request *req,
 	if (cookie != NULL && blk_rq_is_poll(req))
 		nvme_uring_task_meta_cb(ioucmd, IO_URING_F_UNLOCKED);
 	else
-		io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_meta_cb);
+		io_uring_cmd_do_in_task_lazy(ioucmd, nvme_uring_task_meta_cb);
 
 	return RQ_END_IO_NONE;
 }