Re: [PATCH v2] common/rc: don't clear superblock for zoned scratch pools

[David Disseldorp <ddiss@suse.de>]

Hi Johannes,

On Mon, 27 Feb 2023 00:27:17 -0800, Johannes Thumshirn wrote:

> _require_scratch_dev_pool() zeros the first 100 sectors of each device to
> clear eventual remains of older filesystems.
> 
> On zoned devices this won't work as a plain dd will end up creating
> unaligned write errors failing all subsequent actions on the device.
> 
> For zoned devices it is enough to simply reset the first two zones of the
> device to achieve the same result.
> 
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>  common/rc | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/common/rc b/common/rc
> index 654730b21ead..739abbdbfc8c 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -3459,9 +3459,15 @@ _require_scratch_dev_pool()
>  		            exit 1
>  		        fi
>  		fi
> -		# to help better debug when something fails, we remove
> -		# traces of previous btrfs FS on the dev.
> -		dd if=/dev/zero of=$i bs=4096 count=100 > /dev/null 2>&1
> +		# To help better debug when something fails, we remove
> +		# traces of previous btrfs FS on the dev. For zoned devices we
> +		# can't use dd as it'll lead to unaligned writes so simply
> +		# reset the first two zones.
> +		if [ "`_zone_type "$i"`" = "none" ]; then
> +			dd if=/dev/zero of=$i bs=4096 count=100 > /dev/null 2>&1
> +		else
> +			blkzone reset -c 2 $i
> +		fi

IIUC, any output from blkzone reset will cause test failures - is that
an intention here, or should output go to /dev/null like dd?

Looks fine otherwise.

Cheers, David