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|
{ config, lib, pkgs, utils, ... }:
with lib;
let
inInitrd = any (fs: fs == "btrfs") config.boot.initrd.supportedFilesystems;
inSystem = any (fs: fs == "btrfs") config.boot.supportedFilesystems;
cfgScrub = config.services.btrfs.autoScrub;
enableAutoScrub = cfgScrub.enable;
enableBtrfs = inInitrd || inSystem || enableAutoScrub;
in
{
options = {
# One could also do regular btrfs balances, but that shouldn't be necessary
# during normal usage and as long as the filesystems aren't filled near capacity
services.btrfs.autoScrub = {
enable = mkEnableOption "regular btrfs scrub";
fileSystems = mkOption {
type = types.listOf types.path;
example = [ "/" ];
description = ''
List of paths to btrfs filesystems to regularily call <command>btrfs scrub</command> on.
Defaults to all mount points with btrfs filesystems.
If you mount a filesystem multiple times or additionally mount subvolumes,
you need to manually specify this list to avoid scrubbing multiple times.
'';
};
interval = mkOption {
default = "monthly";
type = types.str;
example = "weekly";
description = ''
Systemd calendar expression for when to scrub btrfs filesystems.
The recommended period is a month but could be less
(<citerefentry><refentrytitle>btrfs-scrub</refentrytitle>
<manvolnum>8</manvolnum></citerefentry>).
See
<citerefentry><refentrytitle>systemd.time</refentrytitle>
<manvolnum>7</manvolnum></citerefentry>
for more information on the syntax.
'';
};
};
};
config = mkMerge [
(mkIf enableBtrfs {
system.fsPackages = [ pkgs.btrfs-progs ];
boot.initrd.kernelModules = mkIf inInitrd [ "btrfs" ];
boot.initrd.availableKernelModules = mkIf inInitrd (
[ "crc32c" ]
++ optionals (config.boot.kernelPackages.kernel.kernelAtLeast "5.5") [
# Needed for mounting filesystems with new checksums
"xxhash_generic"
"blake2b_generic"
"sha256_generic" # Should be baked into our kernel, just to be sure
]
);
boot.initrd.extraUtilsCommands = mkIf inInitrd
''
copy_bin_and_libs ${pkgs.btrfs-progs}/bin/btrfs
ln -sv btrfs $out/bin/btrfsck
ln -sv btrfsck $out/bin/fsck.btrfs
'';
boot.initrd.extraUtilsCommandsTest = mkIf inInitrd
''
$out/bin/btrfs --version
'';
boot.initrd.postDeviceCommands = mkIf inInitrd
''
btrfs device scan
'';
})
(mkIf enableAutoScrub {
assertions = [
{
assertion = cfgScrub.enable -> (cfgScrub.fileSystems != []);
message = ''
If 'services.btrfs.autoScrub' is enabled, you need to have at least one
btrfs file system mounted via 'fileSystems' or specify a list manually
in 'services.btrfs.autoScrub.fileSystems'.
'';
}
];
# This will yield duplicated units if the user mounts a filesystem multiple times
# or additionally mounts subvolumes, but going the other way around via devices would
# yield duplicated units when a filesystem spans multiple devices.
# This way around seems like the more sensible default.
services.btrfs.autoScrub.fileSystems = mkDefault (mapAttrsToList (name: fs: fs.mountPoint)
(filterAttrs (name: fs: fs.fsType == "btrfs") config.fileSystems));
# TODO: Did not manage to do it via the usual btrfs-scrub@.timer/.service
# template units due to problems enabling the parameterized units,
# so settled with many units and templating via nix for now.
# https://github.com/NixOS/nixpkgs/pull/32496#discussion_r156527544
systemd.timers = let
scrubTimer = fs: let
fs' = utils.escapeSystemdPath fs;
in nameValuePair "btrfs-scrub-${fs'}" {
description = "regular btrfs scrub timer on ${fs}";
wantedBy = [ "timers.target" ];
timerConfig = {
OnCalendar = cfgScrub.interval;
AccuracySec = "1d";
Persistent = true;
};
};
in listToAttrs (map scrubTimer cfgScrub.fileSystems);
systemd.services = let
scrubService = fs: let
fs' = utils.escapeSystemdPath fs;
in nameValuePair "btrfs-scrub-${fs'}" {
description = "btrfs scrub on ${fs}";
# scrub prevents suspend2ram or proper shutdown
conflicts = [ "shutdown.target" "sleep.target" ];
before = [ "shutdown.target" "sleep.target" ];
serviceConfig = {
# simple and not oneshot, otherwise ExecStop is not used
Type = "simple";
Nice = 19;
IOSchedulingClass = "idle";
ExecStart = "${pkgs.btrfs-progs}/bin/btrfs scrub start -B ${fs}";
# if the service is stopped before scrub end, cancel it
ExecStop = pkgs.writeShellScript "btrfs-scrub-maybe-cancel" ''
(${pkgs.btrfs-progs}/bin/btrfs scrub status ${fs} | ${pkgs.gnugrep}/bin/grep finished) || ${pkgs.btrfs-progs}/bin/btrfs scrub cancel ${fs}
'';
};
};
in listToAttrs (map scrubService cfgScrub.fileSystems);
})
];
}
|