From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ming Lei <ming.lei-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH] blk-throtl: avoid double charge of bio IOPS due to split
Date: Mon, 10 Jan 2022 18:51:26 +0800
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To: brookxu <brookxu.cn-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

Hi Chunguang,

On Mon, Jan 10, 2022 at 04:29:23PM +0800, brookxu wrote:
> From: Chunguang Xu <brookxu-1Nz4purKYjRBDgjK7y7TUQ@public.gmane.org>
> 
> After commit 900e08075202("block: move queue enter logic into
> blk_mq_submit_bio()"), submit_bio_checks() moved to __submit_bio_fops()
> and blk_mq_submit_bio(). The IOs go through blk_mq_submit_bio()
> may be splited before entering blk-throtl, so we need to check
> whether the BIO is throttled, and only update the io_split_cnt
> for the THROTTLED bio to avoid double charge.

Today Jens has merged the patch[1] of "block: don't protect
submit_bio_checks by q_usage_counter", so the behavior is switched
back to previous behavior: running bio check before calling
blk_mq_submit_bio() or ->submit_bio().

Then looks your patch isn't needn't any more.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?h=for-5.17/block&id=9d497e2941c30a060ba62d5485b3bc9d91ffb09e


Thanks,
Ming