diff --git a/calamares/modules/mount.conf b/calamares/modules/mount.conf
index bb28eed..aa38fe2 100644
--- a/calamares/modules/mount.conf
+++ b/calamares/modules/mount.conf
@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # Mount filesystems in the target (generally, before treating the
 # target as a usable chroot / "live" system). Filesystems are
 # automatically mounted from the partitioning module. Filesystems
@@ -9,10 +12,13 @@
 # Extra filesystems to mount. The key's value is a list of entries; each
 # entry has four keys:
 #   - device    The device node to mount
-#   - fs        The filesystem type to use
+#   - fs (optional) The filesystem type to use
 #   - mountPoint Where to mount the filesystem
 #   - options (optional) Extra options to pass to mount(8)
 #
+# The device is not mounted if the mountPoint is unset or if the fs is
+# set to unformatted.
+#
 extraMounts:
     - device: proc
       fs: proc
@@ -34,3 +40,17 @@ extraMountsEfi:
     - device: efivarfs
       fs: efivarfs
       mountPoint: /sys/firmware/efi/efivars
+
+# 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.
+
+btrfsSubvolumes:
+    - mountPoint: /
+      subvolume: /@
+    - mountPoint: /home
+      subvolume: /@home
+    - mountPoint: /var/cache
+      subvolume: /@cache
+    - mountPoint: /var/log
+      subvolume: /@log