linux-kernel - Re: [PATCH] blk: avoid divide-by-zero with zero granularity

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Message-ID: <CAEK8JBD68oTcuV+Cf-S1Vv-n6nyr5UM_zWA5iJFHP=UvQ14AZg@mail.gmail.com>
Date:   Tue, 12 Jan 2021 23:34:06 +0800
From:   Feng Li <lifeng1519@...il.com>
To:     Li Feng <fengli@...rtx.com>
Cc:     Jens Axboe <axboe@...nel.dk>,
        "open list:BLOCK LAYER" <linux-block@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] blk: avoid divide-by-zero with zero granularity

I'm sorry, ignore this one.

Li Feng <fengli@...rtx.com> 于2021年1月12日周二 下午11:30写道：
>
> If the physical_block_size and io_min is less than a sector, the
> 'granularity >> SECTOR_SHIFT' will be zero.
>
> Signed-off-by: Li Feng <fengli@...rtx.com>
> ---
>  include/linux/blkdev.h | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index f94ee3089e01..4d029e95adb4 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1485,6 +1485,10 @@ static inline int queue_alignment_offset(const struct request_queue *q)
>  static inline int queue_limit_alignment_offset(struct queue_limits *lim, sector_t sector)
>  {
>         unsigned int granularity = max(lim->physical_block_size, lim->io_min);
> +       granularity = granularity >> SECTOR_SHIFT;
> +       if (!granularity)
> +               return 0;
> +
>         unsigned int alignment = sector_div(sector, granularity >> SECTOR_SHIFT)
>                 << SECTOR_SHIFT;
>
> --
> 2.29.2
>