[PATCH 2/2] block: remove blk_mq_in_flight() and blk_mq_in_flight_rw()

[Yu Kuai]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

Now that blk-mq also use per_cpu counter to trace inflight as bio-based
device, they can be replaced by part_in_flight() and part_in_flight_rw()
directly.

Noted that there will be a change that inflight will be accounted from
blk_account_io_start() instead of blk_mq_start_request(). This also fix
an inconsistence for rq-based device that if there are rq allocated but
not started, io_ticks will be updated from blk_account_io_start() but not
from part_stat_show() or diskstats_show(). For consequence, for example:

blk_account_io_start  -> 0s
-> something is wrong with driver, rq can't be dispatched to driver
-> finially the driver recovers
blk_mq_start_request  -> 10s

Then in this case, if user is using "iostat 1", then user will found
that 'util' is 0 from 0s-9s, because diskstats_show() doesn't update
io_ticks, then in 9s-10s user will found 'util' is 1000%.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
 block/blk-mq.c | 32 --------------------------------
 block/blk-mq.h |  5 -----
 block/genhd.c  | 18 +++---------------
 3 files changed, 3 insertions(+), 52 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 82045f0ab5ba..dfbb4e24f04a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -87,38 +87,6 @@ struct mq_inflight {
 	unsigned int inflight[2];
 };
 
-static bool blk_mq_check_inflight(struct request *rq, void *priv)
-{
-	struct mq_inflight *mi = priv;
-
-	if (rq->part && blk_do_io_stat(rq) &&
-	    (!mi->part->bd_partno || rq->part == mi->part) &&
-	    blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT)
-		mi->inflight[rq_data_dir(rq)]++;
-
-	return true;
-}
-
-unsigned int blk_mq_in_flight(struct request_queue *q,
-		struct block_device *part)
-{
-	struct mq_inflight mi = { .part = part };
-
-	blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
-
-	return mi.inflight[0] + mi.inflight[1];
-}
-
-void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
-		unsigned int inflight[2])
-{
-	struct mq_inflight mi = { .part = part };
-
-	blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
-	inflight[0] = mi.inflight[0];
-	inflight[1] = mi.inflight[1];
-}
-
 void blk_freeze_queue_start(struct request_queue *q)
 {
 	mutex_lock(&q->mq_freeze_lock);
diff --git a/block/blk-mq.h b/block/blk-mq.h
index f75a9ecfebde..aa92e1317f18 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -236,11 +236,6 @@ static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
 	return hctx->nr_ctx && hctx->tags;
 }
 
-unsigned int blk_mq_in_flight(struct request_queue *q,
-		struct block_device *part);
-void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
-		unsigned int inflight[2]);
-
 static inline void blk_mq_put_dispatch_budget(struct request_queue *q,
 					      int budget_token)
 {
diff --git a/block/genhd.c b/block/genhd.c
index 782a42718965..9c64d34b7dc3 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -954,15 +954,10 @@ ssize_t part_stat_show(struct device *dev,
 		       struct device_attribute *attr, char *buf)
 {
 	struct block_device *bdev = dev_to_bdev(dev);
-	struct request_queue *q = bdev_get_queue(bdev);
 	struct disk_stats stat;
 	unsigned int inflight;
 
-	if (queue_is_mq(q))
-		inflight = blk_mq_in_flight(q, bdev);
-	else
-		inflight = part_in_flight(bdev);
-
+	inflight = part_in_flight(bdev);
 	if (inflight) {
 		part_stat_lock();
 		update_io_ticks(bdev, jiffies, true);
@@ -1003,13 +998,9 @@ ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
 			   char *buf)
 {
 	struct block_device *bdev = dev_to_bdev(dev);
-	struct request_queue *q = bdev_get_queue(bdev);
 	unsigned int inflight[2];
 
-	if (queue_is_mq(q))
-		blk_mq_in_flight_rw(q, bdev, inflight);
-	else
-		part_in_flight_rw(bdev, inflight);
+	part_in_flight_rw(bdev, inflight);
 
 	return sprintf(buf, "%8u %8u\n", inflight[0], inflight[1]);
 }
@@ -1251,11 +1242,8 @@ static int diskstats_show(struct seq_file *seqf, void *v)
 	xa_for_each(&gp->part_tbl, idx, hd) {
 		if (bdev_is_partition(hd) && !bdev_nr_sectors(hd))
 			continue;
-		if (queue_is_mq(gp->queue))
-			inflight = blk_mq_in_flight(gp->queue, hd);
-		else
-			inflight = part_in_flight(hd);
 
+		inflight = part_in_flight(hd);
 		if (inflight) {
 			part_stat_lock();
 			update_io_ticks(hd, jiffies, true);
-- 
2.39.2