linux-kernel - Re: [PATCH v2 04/12] block: prohibit calls to bio_chain

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Message-ID: <CAHc6FU6dmK1udCgj9vMj1ew-4+bZOK7BA47kyEgONEwGg42veg@mail.gmail.com>
Date: Fri, 28 Nov 2025 13:57:59 +0100
From: Andreas Gruenbacher <agruenba@...hat.com>
To: zhangshida <starzhangzsd@...il.com>
Cc: Johannes.Thumshirn@....com, hch@...radead.org, gruenba@...hat.com, 
	ming.lei@...hat.com, siangkao@...ux.alibaba.com, linux-block@...r.kernel.org, 
	linux-bcache@...r.kernel.org, nvdimm@...ts.linux.dev, 
	virtualization@...ts.linux.dev, linux-nvme@...ts.infradead.org, 
	gfs2@...ts.linux.dev, ntfs3@...ts.linux.dev, linux-xfs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, zhangshida@...inos.cn
Subject: Re: [PATCH v2 04/12] block: prohibit calls to bio_chain_endio

On Fri, Nov 28, 2025 at 9:33 AM zhangshida <starzhangzsd@...il.com> wrote:
> From: Shida Zhang <zhangshida@...inos.cn>
>
> Now that all potential callers of bio_chain_endio have been
> eliminated, completely prohibit any future calls to this function.
>
> Suggested-by: Ming Lei <ming.lei@...hat.com>
> Suggested-by: Andreas Gruenbacher <agruenba@...hat.com>
> Suggested-by: Christoph Hellwig <hch@...radead.org>
> Signed-off-by: Shida Zhang <zhangshida@...inos.cn>
> ---
>  block/bio.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/block/bio.c b/block/bio.c
> index aa43435c15f..2473a2c0d2f 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -323,8 +323,13 @@ static struct bio *__bio_chain_endio(struct bio *bio)
>         return parent;
>  }
>
> +/**
> + * This function should only be used as a flag and must never be called.
> + * If execution reaches here, it indicates a serious programming error.
> + */
>  static void bio_chain_endio(struct bio *bio)
>  {
> +       BUG_ON(1);

The below call is dead code and should be removed. With that, nothing
remains of the first patch in this queue ("block: fix incorrect logic
in bio_chain_endio") and that patch can be dropped.

>         bio_endio(bio);
>  }
>
> --
> 2.34.1
>

Thanks,
Andreas