block/blk-iolatency: Add the processing flow of the chained bio in the QoS and define the related types to solve the problem of incorrect inflight processing in the QoS. The usage of the done_split_bio abstract function in the blk-iolatency project.

block/bio.c

@@ -1733,6 +1733,8 @@ static inline bool bio_remaining_done(struct bio *bio)
 		return true;
 	}
 
+	rq_qos_done_split_bio(bio);
+
 	return false;
 }
 

block/blk-iolatency.c

@@ -632,6 +632,39 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
 	}
 }
 
+static void blkcg_iolatency_done_split_bio(struct rq_qos *rqos, struct bio *bio)
+{
+	struct blkcg_gq *blkg;
+	struct rq_wait *rqw;
+	struct iolatency_grp *iolat;
+	int inflight = 0;
+
+	blkg = bio->bi_blkg;
+	if (!blkg || !bio_flagged(bio, BIO_QOS_CHAIN_CHILD))
+		return;
+
+	iolat = blkg_to_lat(bio->bi_blkg);
+	if (!iolat)
+		return;
+
+	if (!iolat->blkiolat->enabled)
+		return;
+
+	while (blkg && blkg->parent) {
+		iolat = blkg_to_lat(blkg);
+		if (!iolat) {
+			blkg = blkg->parent;
+			continue;
+		}
+		rqw = &iolat->rq_wait;
+
+		inflight = atomic_dec_return(&rqw->inflight);
+		WARN_ON_ONCE(inflight < 0);
+
+		blkg = blkg->parent;
+	}
+}
+
 static void blkcg_iolatency_exit(struct rq_qos *rqos)
 {
 	struct blk_iolatency *blkiolat = BLKIOLATENCY(rqos);
@@ -645,6 +678,7 @@ static void blkcg_iolatency_exit(struct rq_qos *rqos)
 static const struct rq_qos_ops blkcg_iolatency_ops = {
 	.throttle = blkcg_iolatency_throttle,
 	.done_bio = blkcg_iolatency_done_bio,
+	.done_split_bio = blkcg_iolatency_done_split_bio,
 	.exit = blkcg_iolatency_exit,
 };
 

block/blk-merge.c

@@ -151,8 +151,13 @@ static struct bio *bio_submit_split(struct bio *bio, int split_sectors)
 	if (split_sectors) {
 		bio = bio_submit_split_bioset(bio, split_sectors,
 				&bio->bi_bdev->bd_disk->bio_split);
-		if (bio)
+		if (bio) {
 			bio->bi_opf |= REQ_NOMERGE;
+			/* Fix the issue where the inflight statistics
+			 * of the chained bio in the QoS are incorrect.
+			 */
+			bio_set_flag(bio, BIO_QOS_CHAIN_CHILD);
+		}
 	}
 
 	return bio;

block/blk-rq-qos.h

@@ -45,6 +45,7 @@ struct rq_qos_ops {
 	void (*cleanup)(struct rq_qos *, struct bio *);
 	void (*queue_depth_changed)(struct rq_qos *);
 	void (*exit)(struct rq_qos *);
+	void (*done_split_bio)(struct rq_qos *, struct bio *);
 	const struct blk_mq_debugfs_attr *debugfs_attrs;
 };
 
@@ -108,6 +109,7 @@ void __rq_qos_throttle(struct rq_qos *rqos, struct bio *bio);
 void __rq_qos_track(struct rq_qos *rqos, struct request *rq, struct bio *bio);
 void __rq_qos_merge(struct rq_qos *rqos, struct request *rq, struct bio *bio);
 void __rq_qos_done_bio(struct rq_qos *rqos, struct bio *bio);
+void __rq_qos_done_split_bio(struct rq_qos *rqos, struct bio *bio);
 void __rq_qos_queue_depth_changed(struct rq_qos *rqos);
 
 static inline void rq_qos_cleanup(struct request_queue *q, struct bio *bio)
@@ -157,6 +159,15 @@ static inline void rq_qos_done_bio(struct bio *bio)
 		__rq_qos_done_bio(q->rq_qos, bio);
 }
 
+static inline void rq_qos_done_split_bio(struct bio *bio)
+{
+	if (bio->bi_bdev && bio_flagged(bio, BIO_QOS_CHAIN_CHILD)) {
+		struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+		if (q->rq_qos)
+			__rq_qos_done_split_bio(q->rq_qos, bio);
+	}
+}
+
 static inline void rq_qos_throttle(struct request_queue *q, struct bio *bio)
 {
 	if (test_bit(QUEUE_FLAG_QOS_ENABLED, &q->queue_flags) && q->rq_qos) {

include/linux/blk_types.h

@@ -322,6 +322,8 @@ enum {
 	BIO_REMAPPED,
 	BIO_ZONE_WRITE_PLUGGING, /* bio handled through zone write plugging */
 	BIO_EMULATES_ZONE_APPEND, /* bio emulates a zone append operation */
+	BIO_QOS_CHAIN_CHILD,    /* chained bio child, used for segmenting out
+				* the bio */
 	BIO_FLAG_LAST
 };