Add default configuration

src/modules/mount/mount.conf

@@ -19,6 +19,10 @@
 # The device is not mounted if the mountPoint is unset or if the fs is
 # set to unformatted.
 #
+---
+# Btrfs subvolumes to create if root filesystem is on btrfs volume.
+# If mountpoint is mounted already to another partition, it is ignored.
+# Separate subvolume for swapfile is handled separately and automatically.
 extraMounts:
     - device: proc
       fs: proc
@@ -40,3 +44,13 @@ extraMountsEfi:
     - device: efivarfs
       fs: efivarfs
       mountPoint: /sys/firmware/efi/efivars
+
+btrfsSubvolumes:
+    - mountPoint: /
+      subvolume: @
+    - mountPoint: /home
+      subvolume: @home
+    - mountPoint: /var/cache
+      subvolume: @cache
+    - mountPoint: /var/log
+      subvolume: @log