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.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
 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;