linux-kernel - Re: [PATCH v2] block: simplify blksize

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Date:   Sat, 29 Oct 2022 20:00:58 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Dawei Li <set_pte_at@...look.com>, axboe@...nel.dk
Cc:     hch@....de, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] block: simplify blksize_bits() implementation

On 10/29/22 19:17, Dawei Li wrote:
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 57ed49f20d2e..7b537afe8b38 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1349,12 +1349,7 @@ static inline int blk_rq_aligned(struct request_queue *q, unsigned long addr,
>   /* assumes size > 256 */
>   static inline unsigned int blksize_bits(unsigned int size)
>   {
> -	unsigned int bits = 8;
> -	do {
> -		bits++;
> -		size >>= 1;
> -	} while (size > 256);
> -	return bits;
> +	return order_base_2((size + SECTOR_SIZE - 1) >> SECTOR_SHIFT) + SECTOR_SHIFT;
>   }

Why the rounding ("+ SECTOR_SIZE - 1")? The blksize_bits() argument 
should be an argument of two.

Thanks,

Bart.