Split initramfs copying logic into new module, enable in debug mode only

1 files changed, 23 insertions, 0 deletions

diff --git a/modules.d/copy-initrd/hooks/copy-initramfs-into-newroot.sh b/modules.d/copy-initrd/hooks/copy-initramfs-into-newroot.sh
new file mode 100755
index 00000000..cdb3f50a
--- /dev/null
+++ b/modules.d/copy-initrd/hooks/copy-initramfs-into-newroot.sh
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# -*- coding: utf-8 -*-
+type emergency_shell >/dev/null 2>&1 || source /lib/dracut-lib.sh
+
+# Needed to be able to go back to dracut at system shutdown.
+# only do this if there is enough space in /run since systemd decided to limit
+# some tmpfs to 10% of the memory size breaking the system with low memory...
+# See: https://github.com/systemd/systemd/commit/b67ec8e5b2e1a74d7e9a3a2b3ac60b7b2e39d4ea
+_run_size_kb="$(slx-tools fs_path_space /run | cut -d' ' -f2)"
+_initrd_block_size="$( stat -f / -c%S)"
+_initrd_total_blocks="$(stat -f / -c%b)"
+_initrd_free_blocks="$(stat -f / -c%a)"
+_initrd_used_blocks="$(( _initrd_total_blocks - _initrd_free_blocks ))"
+_initrd_size_kb="$(( ( _initrd_used_blocks * _initrd_block_size ) / 1024 ))"
+if [ "$(( _run_size_kb - _initrd_size_kb ))" -ge "200000" ]; then
+	# more than 200MB space, should be safe to copy initramfs over
+	temporary_directory_path="$(mktemp --directory)"
+	mount --options bind / "$temporary_directory_path"
+	cp --recursive --no-target-directory "$temporary_directory_path" /run/initramfs
+	umount "$temporary_directory_path"
+	rm --dir "$temporary_directory_path"
+fi
+