Re: [PATCH v3 2/3] common/zoned: add _create_zloop

[Naohiro Aota <Naohiro.Aota@wdc.com>]

On Mon Oct 13, 2025 at 5:07 PM JST, Johannes Thumshirn wrote:
> Add _create_zloop a helper function for creating a zloop device.
>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>  common/zoned | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
>
> diff --git a/common/zoned b/common/zoned
> index 41697b08..59bebcae 100644
> --- a/common/zoned
> +++ b/common/zoned
> @@ -45,3 +45,32 @@ _require_zloop()
>  	    _notrun "This test requires zoned loopback device support"
>      fi
>  }
> +
> +_find_next_zloop()
> +{
> +    local last_id=$(ls /dev/zloop* 2> /dev/null | grep -E "zloop[0-9]+" | wc -l)
> +    echo $last_id
> +}

This one does not work if well one of a non-end zloop device is removed.
So, how about something like this?

while true; do
	if [[ ! -b /dev/zloop$id ]]; then
		break
	fi
	id=$(( id + 1 ))
done

> +
> +# Create a zloop device
> +# useage: _create_zloop [id] <base_dir> <zone_size> <nr_conv_zones>
> +_create_zloop()

Thinking of the compatibility with _create_loop_device(), it would be good
to return the device name.

> +{
> +    local id=$1

So, I think we can just grab an ID here as above, and

> +
> +    if [ -n "$2" ]; then
> +        local base_dir=",base_dir=$2"
> +    fi
> +
> +    if [ -n "$3" ]; then
> +        local zone_size=",zone_size_mb=$3"
> +    fi
> +
> +    if [ -n "$4" ]; then
> +        local conv_zones=",conv_zones=$4"
> +    fi

mkdir -p $base_dir/$id here. I think it's enough to run a workload on an empty
zloop device.

Or, should we also support creating a zloop device from an existing file
structure?

> +
> +    local zloop_args="add id=$id$base_dir$zone_size$conv_zones"
> +
> +    echo "$zloop_args" > /dev/zloop-control
> +}