Support building templates with BTRFS as rootfs

QubesOS/qubes-issues#7310

Makefile

@@ -18,6 +18,7 @@ TEMPLATE_ENV_WHITELIST += \
 	TEMPLATE_FLAVOR_DIR TEMPLATE_OPTIONS APPMENUS_DIR \
 	VERBOSE DEBUG PATH BUILDER_DIR SRC_DIR DISCARD_PREPARED_IMAGE \
 	TEMPLATE_ROOT_WITH_PARTITIONS TEMPLATE_ROOT_SIZE \
+	TEMPLATE_ROOT_FSTYPE \
 	USE_QUBES_REPO_VERSION USE_QUBES_REPO_TESTING \
 	BUILDER_TURBO_MODE REPO_PROXY FEDORA_MIRROR \
 	CENTOS_MIRROR EPEL_MIRROR QUBES_MIRROR \

prepare_image

@@ -32,6 +32,10 @@ if [ -z "$TEMPLATE_ROOT_SIZE" ]; then
     TEMPLATE_ROOT_SIZE=10G
 fi
 
+if [ -z "$TEMPLATE_ROOT_FSTYPE" ]; then
+    TEMPLATE_ROOT_FSTYPE=ext4
+fi
+
 # ------------------------------------------------------------------------------
 # Make sure INSTALLDIR exists
 # ------------------------------------------------------------------------------
@@ -82,10 +86,28 @@ EOF
     udevadm settle --exit-if-exists="$IMG_DEV"
 
     echo "-> Creating filesystem..."
-    /sbin/mkfs.ext4 -q -F "${IMG_DEV}" || exit 1
+    case "$TEMPLATE_ROOT_FSTYPE" in
+        ext4)
+            /sbin/mkfs.ext4 -q -F "${IMG_DEV}" || exit 1
+            ;;
+        btrfs)
+            /sbin/mkfs.btrfs -q -f "${IMG_DEV}" || exit 1
+            mount "${IMG_DEV}" "${INSTALLDIR}" || exit 1
+            btrfs subvolume create "${INSTALLDIR}/root" || exit 1
+            umount "${INSTALLDIR}" || exit 1
+            ;;
+        *)
+            echo "Unsupported filesystem $TEMPLATE_ROOT_FSTYPE" >&2
+            exit 1
+            ;;
+    esac
 fi
 
-mount "${IMG_DEV}" "${INSTALLDIR}" || exit 1
+if [ "$TEMPLATE_ROOT_FSTYPE" = "btrfs" ]; then
+    mount -o subvol=/root "${IMG_DEV}" "${INSTALLDIR}" || exit 1
+else
+    mount "${IMG_DEV}" "${INSTALLDIR}" || exit 1
+fi
 trap "umount_kill $(readlink -m ${INSTALLDIR})" EXIT
 "${SCRIPTSDIR}/01_install_core.sh"
 

qubeize_image

@@ -79,14 +79,23 @@ else
     IMG_DEV=${IMG_LOOP}
 fi
 udevadm settle --exit-if-exists="$IMG_DEV"
-mount "$IMG_DEV" mnt || exit 1
+if [ "$TEMPLATE_ROOT_FSTYPE" = "btrfs" ]; then
+    mount -o subvol=/root "${IMG_DEV}" mnt || exit 1
+else
+    mount "${IMG_DEV}" mnt || exit 1
+fi
 export INSTALLDIR=mnt
 
 # ------------------------------------------------------------------------------
 # Run qubeize script
 # ------------------------------------------------------------------------------
 "$SCRIPTSDIR/04_install_qubes.sh"
 
+if [ "$TEMPLATE_ROOT_FSTYPE" = "btrfs" ]; then
+    # patch fstab
+    sed -i -e 's:dmroot.*ext4.*:dmroot / btrfs defaults,discard,noatime,subvol=/root 1 1:' mnt/etc/fstab
+fi
+
 # ------------------------------------------------------------------------------
 # Create App Menus
 # ------------------------------------------------------------------------------