mirror_zfs/cmd/zpool/zpool.d/dm-deps

#!/bin/sh
#
# Show device mapper dependent / underlying devices.  This is useful for
# looking up the /dev/sd* devices associated with a dm or multipath device. 
#

if [ "$1" = "-h" ] ; then
	echo "Show device mapper dependent (underlying) devices."
	exit
fi

dev="$VDEV_PATH"

# If the VDEV path is a symlink, resolve it to a real device
if [ -L "$dev" ] ; then
	dev=$(readlink "$dev")
fi

dev="${dev##*/}"
val=""
if [ -d "/sys/class/block/$dev/slaves" ] ; then
	# ls -C: output in columns, no newlines, two spaces (change to one)
	# shellcheck disable=SC2012
	val=$(ls -C "/sys/class/block/$dev/slaves" | tr -s '[:space:]' ' ')
fi

echo "dm-deps=$val"