Update impermanance setup script.

nodes/hosts/nixy/impermanence.nix

@@ -1,28 +1,26 @@
-{lib, inputs, ...}: {
-  #  Reset root subvolume on boot
-  boot.initrd.postResumeCommands = lib.mkAfter ''
-    mkdir /btrfs_tmp
-      mount /dev/mapper/cryptroot /btrfs_tmp # CONFIRM THIS IS CORRECT FROM findmnt
-      if [[ -e /btrfs_tmp/root ]]; then
-        mkdir -p /btrfs_tmp/old_roots
-        timestamp=$(date --date="@$(stat -c %Y /btrfs_tmp/root)" "+%Y-%m-%-d_%H:%M:%S")
-        mv /btrfs_tmp/root "/btrfs_tmp/old_roots/$timestamp"
-      fi
+{
+  config,
+  lib,
+  ...
+}: {
+  boot.initrd.postDeviceCommands = lib.mkAfter ''
+    echo "Rollback running" > /mnt/rollback.log
+     mkdir -p /mnt
+     mount -t btrfs /dev/mapper/cryptroot /mnt
 
-      delete_subvolume_recursively() {
-        IFS=$'\n'
-        for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
-          delete_subvolume_recursively "/btrfs_tmp/$i"
-        done
-        btrfs subvolume delete "$1"
-      }
-
-      for i in $(find /btrfs_tmp/old_roots/ -maxdepth 1 -mtime +30); do
-        delete_subvolume_recursively "$i"
+     # Recursively delete all nested subvolumes inside /mnt/root
+     btrfs subvolume list -o /mnt/root | cut -f9 -d' ' | while read subvolume; do
+       echo "Deleting /$subvolume subvolume..." >> /mnt/rollback.log
+       btrfs subvolume delete "/mnt/$subvolume"
      done
 
-      btrfs subvolume create /btrfs_tmp/root
-      umount /btrfs_tmp
+     echo "Deleting /root subvolume..." >> /mnt/rollback.log
+     btrfs subvolume delete /mnt/root
+
+     echo "Restoring blank /root subvolume..." >> /mnt/rollback.log
+     btrfs subvolume snapshot /mnt/root-blank /mnt/root
+
+     umount /mnt
   '';
 
   # Use /persist as the persistence root, matching Disko's mountpoint