72 lines
2.1 KiB
Nix
72 lines
2.1 KiB
Nix
{ lib, ... }:
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{
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imports = [ (import ./partitions.nix { }) ];
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boot.supportedFilesystems = [ "btrfs" ];
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services.btrfs.autoScrub.enable = true;
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# {{{ Mark a bunch of paths as needed for boot
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fileSystems =
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lib.attrsets.genAttrs
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[
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"/"
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"/nix"
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"/persist/data"
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"/persist/state"
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"/persist/local/cache"
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"/boot"
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]
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(p: {
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neededForBoot = true;
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});
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# }}}
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# {{{ Rollback
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boot.initrd.systemd.services.rollback = {
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description = "Rollback BTRFS root subvolume to a pristine state";
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wantedBy = [ "initrd.target" ];
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after = [ "systemd-cryptsetup@enc.service" ];
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before = [ "sysroot.mount" ];
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unitConfig.DefaultDependencies = "no";
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serviceConfig.Type = "oneshot";
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script = ''
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mkdir -p /mnt
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# We first mount the btrfs root to /mnt
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# so we can manipulate btrfs subvolumes.
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mount -o subvol=/ /dev/mapper/enc /mnt
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# While we're tempted to just delete /root and create
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# a new snapshot from /root-blank, /root is already
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# populated at this point with a number of subvolumes,
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# which makes `btrfs subvolume delete` fail.
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# So, we remove them first.
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#
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# /root contains subvolumes:
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# - /root/var/lib/portables
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# - /root/var/lib/machines
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#
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# I suspect these are related to systemd-nspawn, but
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# since I don't use it I'm not 100% sure.
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# Anyhow, deleting these subvolumes hasn't resulted
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# in any issues so far, except for fairly
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# benign-looking errors from systemd-tmpfiles.
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btrfs subvolume list -o /mnt/root |
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cut -f9 -d' ' |
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while read subvolume; do
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echo "deleting /$subvolume subvolume..."
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btrfs subvolume delete "/mnt/$subvolume"
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done &&
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echo "deleting /root subvolume..." &&
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btrfs subvolume delete /mnt/root
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echo "restoring blank /root subvolume..."
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btrfs subvolume snapshot /mnt/root-blank /mnt/root
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# Once we're done rolling back to a blank snapshot,
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# we can unmount /mnt and continue on the boot process.
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umount /mnt
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'';
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};
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# }}}
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}
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