On 01/02/2021 02:30, Guoqing Jiang wrote:

If user doesn't care about the size and latency of io, and they could
suffer from the additional overhead. So introduce a specific sysfs node
to avoid such mistake.

I would make this patch number 1 in the series and then merge patch 4
(the check for blk_queue_io_extra_stat()) into the patches adding 
blk_additional_latency() and blk_additional_sector().