[PATCH 07/15] blkcg: consolidate bio_issue_init and blkg association

[Dennis Zhou <dennisszhou@gmail.com>]

From: "Dennis Zhou (Facebook)" <dennisszhou@gmail.com>

This removes the now duplicate association logic in blk-throttle and
blk-iolatency. bio_issue_init is moved into blkcg_bio_issue_check and
into the bio clone variants to allow for the future addition of a
latency moving average for IOs.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
---
 block/bio.c                |  2 ++
 block/blk-iolatency.c      | 24 +-----------------------
 block/blk-throttle.c       | 13 +------------
 block/bounce.c             |  2 ++
 include/linux/blk-cgroup.h |  2 ++
 5 files changed, 8 insertions(+), 35 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index e937f9681188..ab41f5b7eb1f 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -610,6 +610,8 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
 	bio->bi_io_vec = bio_src->bi_io_vec;
 
 	bio_clone_blkcg_association(bio, bio_src);
+
+	bio_issue_init(&bio->bi_issue, bio_sectors(bio));
 }
 EXPORT_SYMBOL(__bio_clone_fast);
 
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 22b2ff0440cc..9d7052bad6f7 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -395,34 +395,12 @@ static void blkcg_iolatency_throttle(struct rq_qos *rqos, struct bio *bio,
 				     spinlock_t *lock)
 {
 	struct blk_iolatency *blkiolat = BLKIOLATENCY(rqos);
-	struct blkcg *blkcg;
-	struct blkcg_gq *blkg;
-	struct request_queue *q = rqos->q;
+	struct blkcg_gq *blkg = bio->bi_blkg;
 	bool issue_as_root = bio_issue_as_root_blkg(bio);
 
 	if (!blk_iolatency_enabled(blkiolat))
 		return;
 
-	rcu_read_lock();
-	bio_associate_blkcg(bio, NULL);
-	blkcg = bio_blkcg(bio);
-	blkg = blkg_lookup(blkcg, q);
-	if (unlikely(!blkg)) {
-		if (!lock)
-			spin_lock_irq(q->queue_lock);
-		blkg = __blkg_lookup_create(blkcg, q);
-		if (IS_ERR(blkg))
-			blkg = NULL;
-		if (!lock)
-			spin_unlock_irq(q->queue_lock);
-	}
-	if (!blkg)
-		goto out;
-
-	bio_issue_init(&bio->bi_issue, bio_sectors(bio));
-	bio_associate_blkg(bio, blkg);
-out:
-	rcu_read_unlock();
 	while (blkg && blkg->parent) {
 		struct iolatency_grp *iolat = blkg_to_lat(blkg);
 		if (!iolat) {
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index c626e1f7cdcd..f2b355338894 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2126,21 +2126,11 @@ static inline void throtl_update_latency_buckets(struct throtl_data *td)
 }
 #endif
 
-static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio)
-{
-#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
-	/* fallback to root_blkg if we fail to get a blkg ref */
-	if (bio->bi_css && bio_associate_blkg(bio, tg_to_blkg(tg)))
-		bio_associate_blkg(bio, bio->bi_disk->queue->root_blkg);
-	bio_issue_init(&bio->bi_issue, bio_sectors(bio));
-#endif
-}
-
 bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
 		    struct bio *bio)
 {
 	struct throtl_qnode *qn = NULL;
-	struct throtl_grp *tg = blkg_to_tg(blkg ?: q->root_blkg);
+	struct throtl_grp *tg = blkg_to_tg(blkg);
 	struct throtl_service_queue *sq;
 	bool rw = bio_data_dir(bio);
 	bool throttled = false;
@@ -2159,7 +2149,6 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
 	if (unlikely(blk_queue_bypass(q)))
 		goto out_unlock;
 
-	blk_throtl_assoc_bio(tg, bio);
 	blk_throtl_update_idletime(tg);
 
 	sq = &tg->service_queue;
diff --git a/block/bounce.c b/block/bounce.c
index bc63b3a2d18c..bea3b0cbe4a7 100644
--- a/block/bounce.c
+++ b/block/bounce.c
@@ -259,6 +259,8 @@ static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
 
 	bio_clone_blkcg_association(bio, bio_src);
 
+	bio_issue_init(&bio->bi_issue, bio_sectors(bio));
+
 	return bio;
 }
 
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 9931ec2f4e9e..55c348d66372 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -844,6 +844,8 @@ static inline bool blkcg_bio_issue_check(struct request_queue *q,
 		blkg_rwstat_add(&blkg->stat_ios, bio->bi_opf, 1);
 	}
 
+	bio_issue_init(&bio->bi_issue, bio_sectors(bio));
+
 	return !throtl;
 }
 
-- 
2.17.1