From 579f3853848634ac5ecad1c8b2449f92446e2b84 Mon Sep 17 00:00:00 2001
From: Frederick Grose <fgrose@sugarlabs.org>
Date: Sun, 27 Jan 2013 14:47:17 -0500
Subject: [PATCH] Provide devices to enable booting with
 rd.live.overlay.readonly=1

---
 modules.d/90dmsquash-live/dmsquash-live-root.sh | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/modules.d/90dmsquash-live/dmsquash-live-root.sh b/modules.d/90dmsquash-live/dmsquash-live-root.sh
index f302d44..0b1ed20 100755
--- a/modules.d/90dmsquash-live/dmsquash-live-root.sh
+++ b/modules.d/90dmsquash-live/dmsquash-live-root.sh
@@ -110,18 +110,34 @@ do_live_overlay() {
         umount -l /run/initramfs/overlayfs || :
     fi
 
-    if [ -z "$setup" ]; then
-        if [ -n "$devspec" -a -n "$pathspec" ]; then
+    if [ -z "$setup" -o -n "$readonly_overlay" ]; then
+        if [ -n "$setup" ]; then
+            warn "Using temporary overlay."
+        elif [ -n "$devspec" -a -n "$pathspec" ]; then
             warn "Unable to find persistent overlay; using temporary"
             sleep 5
         fi
 
         dd if=/dev/null of=/overlay bs=1024 count=1 seek=$((512*1024)) 2> /dev/null
-        losetup $OVERLAY_LOOPDEV /overlay
+        if [ -n "$setup" -a -n "$readonly_overlay" ]; then
+            RO_OVERLAY_LOOPDEV=$( losetup -f )
+            losetup $RO_OVERLAY_LOOPDEV /overlay
+        else
+            losetup $OVERLAY_LOOPDEV /overlay
+        fi
     fi
 
     # set up the snapshot
-    echo 0 `blockdev --getsz $BASE_LOOPDEV` snapshot $BASE_LOOPDEV $OVERLAY_LOOPDEV p 8 | dmsetup create $readonly_overlay live-rw
+    sz=$(blockdev --getsz $BASE_LOOPDEV)
+    if [ -n "$readonly_overlay" ]; then
+        echo 0 $sz snapshot $BASE_LOOPDEV $OVERLAY_LOOPDEV p 8 | dmsetup create $readonly_overlay live-ro
+        base="/dev/mapper/live-ro"
+        over=$RO_OVERLAY_LOOPDEV
+    else
+        base=$BASE_LOOPDEV
+        over=$OVERLAY_LOOPDEV
+    fi
+    echo 0 $sz snapshot $base $over p 8 | dmsetup create live-rw
 }
 
 # live cd helper function