[Devel] [PATCH RHEL9 COMMIT] ms/blk-throttle: Fix io statistics for cgroup v1

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.0-284.25.1.vz9.30.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh9-5.14.0-284.25.1.vz9.30.12
------>
commit b4e5e8276dca97ebf4d6349295336077966c2227
Author: Jinke Han <hanjinke.666 at bytedance.com>
Date:   Wed Nov 22 18:14:54 2023 +0200

    ms/blk-throttle: Fix io statistics for cgroup v1
    
    After commit f382fb0bcef4 ("block: remove legacy IO schedulers"),
    blkio.throttle.io_serviced and blkio.throttle.io_service_bytes become
    the only stable io stats interface of cgroup v1, and these statistics
    are done in the blk-throttle code. But the current code only counts the
    bios that are actually throttled. When the user does not add the throttle
    limit, the io stats for cgroup v1 has nothing. I fix it according to the
    statistical method of v2, and made it count all ios accurately.
    
    mFixes: a7b36ee6ba29 ("block: move blk-throtl fast path inline")
    Tested-by: Andrea Righi <andrea.righi at canonical.com>
    Signed-off-by: Jinke Han <hanjinke.666 at bytedance.com>
    Acked-by: Muchun Song <songmuchun at bytedance.com>
    Acked-by: Tejun Heo <tj at kernel.org>
    Link: https://lore.kernel.org/r/20230507170631.89607-1-hanjinke.666@bytedance.com
    Signed-off-by: Jens Axboe <axboe at kernel.dk>
    
    (cherry picked from ms commit ad7c3b41e86b59943a903d23c7b037d820e6270c)
    Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
    
    Feature: fix ms/blkio
---
 block/blk-cgroup.c   | 6 ++++--
 block/blk-throttle.c | 6 ------
 block/blk-throttle.h | 9 +++++++++
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 30d9045805fd..28071357ce21 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1996,6 +1996,9 @@ void blk_cgroup_bio_start(struct bio *bio)
 	struct blkg_iostat_set *bis;
 	unsigned long flags;
 
+	if (!cgroup_subsys_on_dfl(io_cgrp_subsys))
+		return;
+
 	/* Root-level stats are sourced from system-wide IO stats */
 	if (!cgroup_parent(blkcg->css.cgroup))
 		return;
@@ -2027,8 +2030,7 @@ void blk_cgroup_bio_start(struct bio *bio)
 	}
 
 	u64_stats_update_end_irqrestore(&bis->sync, flags);
-	if (cgroup_subsys_on_dfl(io_cgrp_subsys))
-		cgroup_rstat_updated(blkcg->css.cgroup, cpu);
+	cgroup_rstat_updated(blkcg->css.cgroup, cpu);
 	put_cpu();
 }
 
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 847721dc2b2b..dde302231a7e 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2167,12 +2167,6 @@ bool __blk_throtl_bio(struct bio *bio)
 
 	rcu_read_lock();
 
-	if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) {
-		blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf,
-				bio->bi_iter.bi_size);
-		blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1);
-	}
-
 	spin_lock_irq(&q->queue_lock);
 
 	throtl_update_latency_buckets(td);
diff --git a/block/blk-throttle.h b/block/blk-throttle.h
index ef4b7a4de987..d1ccbfe9f797 100644
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -185,6 +185,15 @@ static inline bool blk_should_throtl(struct bio *bio)
 	struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg);
 	int rw = bio_data_dir(bio);
 
+	if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) {
+		if (!bio_flagged(bio, BIO_CGROUP_ACCT)) {
+			bio_set_flag(bio, BIO_CGROUP_ACCT);
+			blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf,
+					bio->bi_iter.bi_size);
+		}
+		blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1);
+	}
+
 	/* iops limit is always counted */
 	if (tg->has_rules_iops[rw])
 		return true;