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Date:   Tue, 11 May 2021 08:11:58 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Song Liu <song@kernel.org>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Guoqing Jiang <jgq516@gmail.com>,
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        Pawe?? Wiejacha <pawel.wiejacha@rtbhouse.com>
Subject: Re: [PATCH] md: don't account io stat for split bio
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On Mon, May 10, 2021 at 11:59:11PM -0700, Song Liu wrote:
> > Yes.  Also if the original bi_end_io is restore before completing the
> > bio you can still override it.
> 
> Do you mean we can somehow avoid cloning the bio?

If you restore the original bi_end_io you might be able to avoid it.
That being said I suspect that always cloning will be more robust.