From: Kemeng Shi shikemeng@huawei.com
mainline inclusion from mainline-v6.2-rc1 commit 84aca0a7e039c8735abc0f89f3f48e9006c0dfc7 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAUKH4 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Consider situation as following (on the default hierarchy): HDD | root (bps limit: 4k) | child (bps limit :8k) | fio bs=8k Rate of fio is supposed to be 4k, but result is 8k. Reason is as following: Size of single IO from fio is larger than bytes allowed in one throtl_slice in child, so IOs are always queued in child group first. When queued IOs in child are dispatched to parent group, BIO_BPS_THROTTLED is set and these IOs will not be limited by tg_within_bps_limit anymore. Fix this by only set BIO_BPS_THROTTLED when the bio traversed the entire tree.
There patch has no influence on situation which is not on the default hierarchy as each group is a single root group without parent.
Acked-by: Tejun Heo tj@kernel.org Signed-off-by: Kemeng Shi shikemeng@huawei.com Link: https://lore.kernel.org/r/20221205115709.251489-3-shikemeng@huaweicloud.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Yu Kuai yukuai3@huawei.com --- block/blk-throttle.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 5e7580dde671..ba2f579a7934 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1079,7 +1079,6 @@ static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) sq->nr_queued[rw]--;
throtl_charge_bio(tg, bio); - bio_set_flag(bio, BIO_BPS_THROTTLED);
/* * If our parent is another tg, we just need to transfer @bio to @@ -1092,6 +1091,7 @@ static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); start_parent_slice_with_credit(tg, parent_tg, rw); } else { + bio_set_flag(bio, BIO_BPS_THROTTLED); throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], &parent_sq->queued[rw]); BUG_ON(tg->td->nr_queued[rw] <= 0);