linux-kernel - Re: [PATCH v2 07/10] block: use sectors_to_npage() and PAGE

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Date:   Thu, 14 May 2020 21:19:16 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Zhen Lei <thunder.leizhen@...wei.com>
Cc:     Minchan Kim <minchan@...nel.org>, Nitin Gupta <ngupta@...are.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Jens Axboe <axboe@...nel.dk>, Coly Li <colyli@...e.de>,
        Kent Overstreet <kent.overstreet@...il.com>,
        Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>,
        linux-block <linux-block@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-mm <linux-mm@...ck.org>, dm-devel <dm-devel@...hat.com>,
        Song Liu <song@...nel.org>,
        linux-raid <linux-raid@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 07/10] block: use sectors_to_npage() and PAGE_SECTORS
 to clean up code

On Thu, May 07, 2020 at 03:50:57PM +0800, Zhen Lei wrote:
> +++ b/block/blk-settings.c
> @@ -150,7 +150,7 @@ void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_secto
>  	unsigned int max_sectors;
>  
>  	if ((max_hw_sectors << 9) < PAGE_SIZE) {
> -		max_hw_sectors = 1 << (PAGE_SHIFT - 9);
> +		max_hw_sectors = PAGE_SECTORS;

Surely this should be:

	if (max_hw_sectors < PAGE_SECTORS) {
		max_hw_sectors = PAGE_SECTORS;

... no?

> -	page = read_mapping_page(mapping,
> -			(pgoff_t)(n >> (PAGE_SHIFT - 9)), NULL);
> +	page = read_mapping_page(mapping, (pgoff_t)sectors_to_npage(n), NULL);

... again, get the type right, and you won't need the cast.