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Date:   Mon, 10 May 2021 07:00:08 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Guoqing Jiang <jgq516@gmail.com>
Cc:     song@kernel.org, linux-raid@vger.kernel.org,
        linux-block@vger.kernel.org, pawel.wiejacha@rtbhouse.com,
        Guoqing Jiang <jiangguoqing@kylinos.cn>
Subject: Re: [PATCH] md: don't account io stat for split bio
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On Sat, May 08, 2021 at 11:48:15AM +0800, Guoqing Jiang wrote:
> It looks like stack overflow happened for split bio, to fix this,
> let's keep split bio untouched in md_submit_bio.
> 
> As a side effect, we need to export bio_chain_endio.

Err, no.  The right answer is to not change ->bi_end_io of bios that
you do not own instead of using a horrible hack to skip accounting for
bios that have no more or less reason to be accounted than others bios.