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Modules/Impermanence: Update subvolume cleanup script

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This commit is contained in:
Christoph Urlacher
2025-07-16 13:35:33 +02:00
parent 680b3123f0
commit 7a6e9e0717
1 changed files with 29 additions and 10 deletions
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39
system/modules/impermanence/default.nix
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@ -3,6 +3,7 @@
lib,
mylib,
username,
pkgs,
...
}: let
inherit (config.modules) impermanence;
@ -105,6 +106,7 @@ in {
(mkUDir ".cache/fish/generated_completions" m755)
(mkUDir ".cache/nix-index" m755)
(mkUDir ".cache/nix-search-tv" m755)
(mkUDir ".cache/nvim" m755)
(mkUDir ".config/beets" m755)
@ -134,17 +136,18 @@ in {
boot.initrd.systemd = {
enable = true;
services.btrfs-volume-cleanup = let
services.impermanence-btrfs-cleanup = let
backupDuration = "7"; # Days
mountDir = "/btrfs_tmp";
persistDir = "${mountDir}/persist";
in {
description = "Clean btrfs subvolumes for impermanence";
description = "Clean impermanent btrfs subvolumes";
wantedBy = ["initrd.target"];
after = ["dev-mapper-crypted.device"];
before = ["sysroot.mount"];
unitConfig.DefaultDependencies = "no";
serviceConfig.Type = "oneshot";
path = ["/bin" config.system.build.extraUtils];
# path = ["/bin" config.system.build.extraUtils pkgs.coreutils-full];
script = ''
mkdir -p ${mountDir}
@ -152,39 +155,55 @@ in {
# Backup old root subvolume
if [[ -e ${mountDir}/root ]]; then
mkdir -p ${mountDir}/old_roots
mkdir -p ${persistDir}/old_roots
timestamp=$(date --date="@$(stat -c %Y ${mountDir}/root)" "+%Y-%m-%-d_%H:%M:%S")
mv ${mountDir}/root "${mountDir}/old_roots/$timestamp"
mv ${mountDir}/root "${persistDir}/old_roots/$timestamp"
echo "Backed up previous root subvolume to ${persistDir}/old_roots/$timestamp"
fi
# Backup old home subvolume
if [[ -e ${mountDir}/home ]]; then
mkdir -p ${mountDir}/old_homes
mkdir -p ${persistDir}/old_homes
timestamp=$(date --date="@$(stat -c %Y ${mountDir}/home)" "+%Y-%m-%-d_%H:%M:%S")
mv ${mountDir}/home "${mountDir}/old_homes/$timestamp"
mv ${mountDir}/home "${persistDir}/old_homes/$timestamp"
echo "Backed up previous home subvolume to ${persistDir}/old_homes/$timestamp"
fi
# Delete a backed up subvolume
delete_subvolume_recursively() {
IFS=$'\n'
# https://github.com/nix-community/impermanence/issues/258#issuecomment-2733383737
# If we accidentally end up with a file or directory under old_roots,
# the code will enumerate all subvolumes under the main volume.
# We don't want to remove everything under true main volume. Only
# proceed if this path is a btrfs subvolume (inode=256).
if [ $(stat -c %i "$1") -ne 256 ]; then return; fi
for subvol in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
delete_subvolume_recursively "${mountDir}/$subvol"
delete_subvolume_recursively "${persistDir}/$subvol"
done
btrfs subvolume delete "$1"
echo "Deleted old subvolume $1"
}
# Delete old roots
for old_root in $(find ${mountDir}/old_roots/ -maxdepth 1 -mtime +${backupDuration}); do
for old_root in $(find ${persistDir}/old_roots/ -maxdepth 1 -mtime +${backupDuration}); do
delete_subvolume_recursively "$old_root"
done
# Delete old homes
for old_home in $(find ${mountDir}/old_homes/ -maxdepth 1 -mtime +${backupDuration}); do
for old_home in $(find ${persistDir}/old_homes/ -maxdepth 1 -mtime +${backupDuration}); do
delete_subvolume_recursively "$old_home"
done
# Create new root + home subvolumes
btrfs subvolume create ${mountDir}/root
btrfs subvolume create ${mountDir}/home
echo "Created new subvolumes ${mountDir}/root and ${mountDir}/home"
umount ${mountDir}
rmdir ${mountDir}