On Thu, Nov 26, 2020 at 05:48:33PM +0800, Jeffle Xu wrote:

The inflight of partition 0 doesn't include inflight IOs to all
sub-partitions, since currently mq calculates inflight of specific
partition by simply camparing the value of the partition pointer.

Thus the following case is possible:

$ cat /sys/block/vda/inflight
?? ?? ?? ??0 ?? ?? ?? ??0
$ cat /sys/block/vda/vda1/inflight
?? ?? ?? ??0 ?? ?? ??128

Partition 0 should be specially handled since it represents the whole
disk.

I'm not sure and can see arguments for either side.  In doubt we should
stick to historic behavior, can you check what old kernels (especially
before blk-mq) did?