Re: [PATCH v3 1/6] common/rc: fix btrfs mixed mode usage in _scratch_mkfs_sized

[Eryu Guan <guan@eryu.me>]

On Fri, Feb 18, 2022 at 04:31:51PM +0900, Shin'ichiro Kawasaki wrote:
> The helper function _scratch_mkfs_sized needs a couple of improvements
> for btrfs. At first, the function adds --mixed option to mkfs.btrfs when
> the filesystem size is smaller then 256MiB, but this threshold is no
> longer correct and it should be 109MiB. Secondly, the --mixed option

I'm wondering if this 256M -> 109M change was made just recently or was
made on old kernel.

If it was changed just recently, say 5.14 kernel, I suspect that tests
will fail on kernels prior to that change.

But if this change was made on some acient kernels, say 4.10, then I
think we're fine with this patch.

Thanks,
Eryu

> shall not be specified to mkfs.btrfs for zoned devices, since zoned
> devices does not allow mixing metadata blocks and data blocks.
> 
> Suggested-by: Naohiro Aota <naohiro.aota@wdc.com>
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>  common/rc | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/common/rc b/common/rc
> index de60fb7b..74d2d8bd 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -1075,10 +1075,10 @@ _scratch_mkfs_sized()
>  		;;
>  	btrfs)
>  		local mixed_opt=
> -		# minimum size that's needed without the mixed option.
> -		# Ref: btrfs-prog: btrfs_min_dev_size()
> -		# Non mixed mode is also the default option.
> -		(( fssize < $((256 * 1024 *1024)) )) && mixed_opt='--mixed'
> +		# Mixed option is required when the filesystem size is small and
> +		# the device is not zoned. Ref: btrfs-progs: btrfs_min_dev_size()
> +		(( fssize < $((109 * 1024 * 1024)) )) &&
> +			! _scratch_btrfs_is_zoned && mixed_opt='--mixed'
>  		$MKFS_BTRFS_PROG $MKFS_OPTIONS $mixed_opt -b $fssize $SCRATCH_DEV
>  		;;
>  	jfs)
> -- 
> 2.34.1