#!/bin/sh
# Copyright 2018 Google Inc. All Rights Reserved.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

# Expands a filesystem and its corresponding partition (if it exists) to fill
# all available disk space.  Takes as an argument the mountpoint or device to
# expand, with any specification supported by findmnt.
[ $# -ne 1 ] && { echo "Usage: $0 device|mountpoint"; exit 1; }

# Find the device to expand.
if [ -b "$1" ]; then
	dev="$1"
else
	dev="$(findmnt -nfvo SOURCE -- "$1")"
	[ -b "$dev" ] || { echo "Cannot find device for '$1'"; exit 1; }
fi

# If it's a partition, expand that first using growpart.
if [ "$(lsblk -ndo TYPE -- "$dev")" = part ]; then
	disk="$(lsblk -ndpo PKNAME -- "$dev")"
	partnum="${dev##*[!0-9]}"
	growpart "$disk" "$partnum" || { [ $? -ne 1 ] && exit 1; }
fi

# Expand the filesystem.
fs="$(lsblk -ndo FSTYPE -- "$dev")"
mnt="$(lsblk -ndo MOUNTPOINT -- "$dev")"
case "$fs" in
	btrfs) btrfs filesystem resize max "$mnt" || exit 1 ;;
	ext[2-4]) resize2fs -- "$dev" || exit 1 ;;
	xfs) xfs_growfs "$mnt"  || exit 1 ;;
	*) echo "Unsupported filesystem type '$fs'"; exit 1 ;;
esac