Re: [PATCH RESEND 1/2] common/dmlogwrites: Extend _log_writes_init() to accept the specified size

["Darrick J. Wong" <djwong@kernel.org>]

On Sun, Oct 23, 2022 at 06:48:13AM +0000, yangx.jy@fujitsu.com wrote:
> It is unnecssary to always create a log-writes device based on
> the size of the entire underlying device.
> 
> Signed-off-by: Xiao Yang <yangx.jy@fujitsu.com>
> ---
>  common/dmlogwrites | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/common/dmlogwrites b/common/dmlogwrites
> index 9fa1c977..d7b23cec 100644
> --- a/common/dmlogwrites
> +++ b/common/dmlogwrites
> @@ -61,12 +61,20 @@ _require_log_writes_dax_mountopt()
>  
>  _log_writes_init()
>  {
> -	blkdev=$1
> +	local blkdev=$1
> +	local range=$2

Range is a length in ... bytes?  The unit ought to be recorded in a
comment for this function.

With that fixed, this looks ok to me
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> +	local BLK_DEV_SIZE
>  
>  	[ -z "$blkdev" ] && _fail \
>  	"block dev must be specified for _log_writes_init"
>  
> -	local BLK_DEV_SIZE=`blockdev --getsz $blkdev`
> +	if [ -z "$range" ]; then
> +		BLK_DEV_SIZE=`blockdev --getsz $blkdev`
> +	else
> +		local blksz=`blockdev --getss $blkdev`
> +		BLK_DEV_SIZE=$((range / blksz))
> +	fi
> +
>  	LOGWRITES_NAME=logwrites-test
>  	LOGWRITES_DMDEV=/dev/mapper/$LOGWRITES_NAME
>  	LOGWRITES_TABLE="0 $BLK_DEV_SIZE log-writes $blkdev $LOGWRITES_DEV"
> -- 
> 2.34.1