--- xen-unstable/tools/examples/block.orig	2007-11-06 20:01:53.000000000 -0800
+++ xen-unstable/tools/examples/block	2007-11-06 20:03:14.000000000 -0800
@@ -326,7 +326,10 @@
           fatal 'Failed to find an unused loop device'
         fi
 
-        do_or_die losetup "$loopdev" "$file"
+        status=$(losetup "$loopdev" "$file" || echo "failed")
+        if [ -n "$status" ]; then
+          do_or_die losetup -r "$loopdev" "$file"
+        fi
         xenstore_write "$XENBUS_PATH/node" "$loopdev"
         write_dev "$loopdev"
         release_lock "block"