linux-kernel - Re: [dm-devel] [PATCH] dm zoned: Avoid 64-bit division error in dmz_fixup

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Message-ID: <BY5PR04MB690080527BC91E2DC9EDF0BBE7BC0@BY5PR04MB6900.namprd04.prod.outlook.com>
Date:   Thu, 14 May 2020 06:25:02 +0000
From:   Damien Le Moal <Damien.LeMoal@....com>
To:     Nathan Chancellor <natechancellor@...il.com>,
        Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>
CC:     "dm-devel@...hat.com" <dm-devel@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [dm-devel] [PATCH] dm zoned: Avoid 64-bit division error in
 dmz_fixup_devices

On 2020/05/14 14:07, Nathan Chancellor wrote:
> When building arm32 allyesconfig:
> 
> ld.lld: error: undefined symbol: __aeabi_uldivmod
>>>> referenced by dm-zoned-target.c
>>>>               md/dm-zoned-target.o:(dmz_ctr) in archive drivers/built-in.a
> 
> dmz_fixup_devices uses DIV_ROUND_UP with variables of type sector_t. As
> such, it should be using DIV_ROUND_UP_SECTOR_T, which handles this
> automatically.
> 
> Fixes: 70978208ec91 ("dm zoned: metadata version 2")
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
>  drivers/md/dm-zoned-target.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/md/dm-zoned-target.c b/drivers/md/dm-zoned-target.c
> index ea43f6892ced..9c4fd4b04878 100644
> --- a/drivers/md/dm-zoned-target.c
> +++ b/drivers/md/dm-zoned-target.c
> @@ -803,8 +803,9 @@ static int dmz_fixup_devices(struct dm_target *ti)
>  
>  	if (reg_dev) {
>  		reg_dev->zone_nr_sectors = zoned_dev->zone_nr_sectors;
> -		reg_dev->nr_zones = DIV_ROUND_UP(reg_dev->capacity,
> -						 reg_dev->zone_nr_sectors);
> +		reg_dev->nr_zones =
> +			DIV_ROUND_UP_SECTOR_T(reg_dev->capacity,
> +					      reg_dev->zone_nr_sectors);>  		zoned_dev->zone_offset = reg_dev->nr_zones;
>  	}
>  	return 0;
> 
> base-commit: e098d7762d602be640c53565ceca342f81e55ad2
> 

Looks good.

Reviewed-by: Damien Le Moal <damien.lemoal@....com>

-- 
Damien Le Moal
Western Digital Research