On 12/2/20 7:11 PM, 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
>
> While single queue device (on a previous version, e.g. v3.10) has no
> this issue:
>
> $cat /sys/block/sda/sda3/inflight
> 0 33
> $cat /sys/block/sda/inflight
> 0 33
>
> Partition 0 should be specially handled since it represents the whole
> disk. This issue is introduced since commit bf0ddaba65dd ("blk-mq: fix
> sysfs inflight counter").
>
> Besides, this patch can also fix the inflight statistics of part 0 in
> /proc/diskstats. Before this patch, the inflight statistics of part 0
> doesn't include that of sub partitions. (I have marked the 'inflight'
> field with asterisk.)
>
> $cat /proc/diskstats
> 259 0 nvme0n1 45974469 0 367814768 6445794 1 0 1 0 *0* 111062 6445794 0 0 0 0 0 0
> 259 2 nvme0n1p1 45974058 0 367797952 6445727 0 0 0 0 *33* 111001 6445727 0 0 0 0 0 0
>
> This is introduced since commit f299b7c7a9de ("blk-mq: provide internal
> in-flight variant").
>
> Fixes: bf0ddaba65dd ("blk-mq: fix sysfs inflight counter")
> Fixes: f299b7c7a9de ("blk-mq: provide internal in-flight variant")
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
> ---
> v2: update the commit log, adding 'Fixes' tag
Forgot to add 'stable' tag.
> ---
> block/blk-mq.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 55bcee5dc032..04b6b4d21ce6 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -105,7 +105,8 @@ static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
> {
> struct mq_inflight *mi = priv;
>
> - if (rq->part == mi->part && blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT)
> + if ((!mi->part->partno || rq->part == mi->part) &&
> + blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT)
> mi->inflight[rq_data_dir(rq)]++;
>
> return true;
>
--
Thanks,
Jeffle
