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Message-ID: <6f93c6f4-240d-2d61-c53d-b5e66895ebcf@opensource.wdc.com>
Date:   Thu, 28 Jul 2022 12:18:07 +0900
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Subject: Re: [PATCH v8 07/11] dm-zoned: ensure only power of 2 zone sizes are
 allowed
Content-Language: en-US
To:     Pankaj Raghav <p.raghav@samsung.com>, hch@lst.de, axboe@kernel.dk,
        snitzer@kernel.org, Johannes.Thumshirn@wdc.com
Cc:     matias.bjorling@wdc.com, gost.dev@samsung.com,
        linux-kernel@vger.kernel.org, hare@suse.de,
        linux-block@vger.kernel.org, pankydev8@gmail.com,
        bvanassche@acm.org, jaegeuk@kernel.org, dm-devel@redhat.com,
        linux-nvme@lists.infradead.org,
        Luis Chamberlain <mcgrof@kernel.org>
References: <20220727162245.209794-1-p.raghav@samsung.com>
 <CGME20220727162253eucas1p1a5912e0494f6918504cc8ff15ad5d31f@eucas1p1.samsung.com>
 <20220727162245.209794-8-p.raghav@samsung.com>
From:   Damien Le Moal <damien.lemoal@opensource.wdc.com>
Organization: Western Digital Research
In-Reply-To: <20220727162245.209794-8-p.raghav@samsung.com>
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Precedence: bulk

On 7/28/22 01:22, Pankaj Raghav wrote:
> From: Luis Chamberlain <mcgrof@kernel.org>
> 
> dm-zoned relies on the assumption that the zone size is a
> power-of-2(po2) and the zone capacity is same as the zone size.
> 
> Ensure only po2 devices can be used as dm-zoned target until a native
> non po2 support is added.
> 
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
>  drivers/md/dm-zoned-target.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/md/dm-zoned-target.c b/drivers/md/dm-zoned-target.c
> index 95b132b52f33..16499b75c5ee 100644
> --- a/drivers/md/dm-zoned-target.c
> +++ b/drivers/md/dm-zoned-target.c
> @@ -792,6 +792,10 @@ static int dmz_fixup_devices(struct dm_target *ti)
>  				return -EINVAL;
>  			}
>  			zone_nr_sectors = bdev_zone_sectors(bdev);
> +			if (!is_power_of_2(zone_nr_sectors)) {
> +				ti->error = "Zone size is not power of 2";

Let's clarify:

	ti->error = "Zone size is not a power of 2 number of sectors";

> +				return -EINVAL;
> +			}
>  			zoned_dev->zone_nr_sectors = zone_nr_sectors;
>  			zoned_dev->nr_zones = bdev_nr_zones(bdev);
>  		}
> @@ -804,6 +808,10 @@ static int dmz_fixup_devices(struct dm_target *ti)
>  			return -EINVAL;
>  		}
>  		zoned_dev->zone_nr_sectors = bdev_zone_sectors(bdev);
> +		if (!is_power_of_2(zoned_dev->zone_nr_sectors)) {
> +			ti->error = "Zone size is not power of 2";

Same comment.

> +			return -EINVAL;
> +		}
>  		zoned_dev->nr_zones = bdev_nr_zones(bdev);
>  	}
>  


-- 
Damien Le Moal
Western Digital Research