Index: xen-unstable/tools/examples/block
===================================================================
--- xen-unstable.orig/tools/examples/block
+++ xen-unstable/tools/examples/block
@@ -42,6 +42,20 @@ canonicalise_mode()
   fi
 }
 
+##
+# sync_flags mode
+#
+sync_flags()
+{
+  local mode="$1"
+  if expr index "$mode" 'S' >/dev/null
+  then
+    echo "-y"
+  else
+    echo ""
+  fi
+}
+
 
 ##
 # check_sharing device mode
@@ -262,6 +276,7 @@ case "$command" in
         # Canonicalise the file, for sharing check comparison, and the mode
         # for ease of use here.
         file=$(readlink -f "$p") || fatal "$p does not exist."
+        sync=$(sync_flags "$mode")
         mode=$(canonicalise_mode "$mode")
 
         claim_lock "block"
@@ -367,7 +382,7 @@ mount it read-write in a guest domain."
           fatal 'Failed to find an unused loop device'
         fi
 
-        do_or_die losetup "$loopdev" "$file"
+        do_or_die losetup $sync "$loopdev" "$file"
         xenstore_write "$XENBUS_PATH/node" "$loopdev"
         write_dev "$loopdev"
         release_lock "block"