From 0ff82e4656f77afff96c861494aff596dfb9d832 Mon Sep 17 00:00:00 2001
From: Jonathan Bauer
Date: Fri, 14 Aug 2020 13:52:23 +0200
Subject: [dnbd3-rootfs] only copy /run/initramfs if enough space

---
 .../copy-dracut-systemd-files-into-newroot.sh      | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/modules.d/dnbd3-rootfs/hooks/copy-dracut-systemd-files-into-newroot.sh b/modules.d/dnbd3-rootfs/hooks/copy-dracut-systemd-files-into-newroot.sh
index aca83b8e..0cae2b35 100755
--- a/modules.d/dnbd3-rootfs/hooks/copy-dracut-systemd-files-into-newroot.sh
+++ b/modules.d/dnbd3-rootfs/hooks/copy-dracut-systemd-files-into-newroot.sh
@@ -3,11 +3,23 @@
 type emergency_shell >/dev/null 2>&1 || source /lib/dracut-lib.sh
 
 # Needed to be able to go back to dracut at system shutdown.
-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 "$temporary_directory_path"
+# only do this if there is enough space in /run since systemd decided to limit
+# some tmpfs to 10% of the memory size breaking the system with low memory...
+# See: https://github.com/systemd/systemd/commit/b67ec8e5b2e1a74d7e9a3a2b3ac60b7b2e39d4ea
+_run_size_kb="$(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
 
 # Dracut may not be installed on the new root. Thus copy all services over.
 dracut_mount_unit_path="$(systemctl show -p FragmentPath dracut-mount.service \
-- 
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