archbuild/makechrootpkg: Delete subvolumes in roots

The systemd package creates a subvolume at /var/lib/machines (through
tmpfiles), if it can. We need to delete this subvolume before we can
delete the parent subvolume.

Look through the root for inodes with the number 256. These identify
subvolume roots.

1 files changed, 20 insertions, 0 deletions

diff --git a/lib/archroot.sh b/lib/archroot.sh
index 14417aa..989f1e1 100644
--- a/lib/archroot.sh
+++ b/lib/archroot.sh
@@ -20,3 +20,23 @@ check_root() {
 is_btrfs() {
 	[[ -e "$1" && "$(stat -f -c %T "$1")" == btrfs ]]
 }
+
+##
+#  usage : subvolume_delete_recursive( $path )
+#
+#    Find all btrfs subvolumes under and including $path and delete them.
+##
+subvolume_delete_recursive() {
+	local subvol
+
+	is_btrfs "$1" || return 0
+
+	while IFS= read -d $'\0' -r subvol; do
+		if ! btrfs subvolume delete "$subvol" &>/dev/null; then
+			error "Unable to delete subvolume %s" "$subvol"
+			return 1
+		fi
+	done < <(find "$1" -xdev -depth -inum 256 -print0)
+
+	return 0
+}