Index: xen-unstable/tools/examples/block
===================================================================
--- xen-unstable.orig/tools/examples/block
+++ xen-unstable/tools/examples/block
@@ -391,8 +391,18 @@ mount it read-write in a guest domain."
 
       file)
         node=$(xenstore_read "$XENBUS_PATH/node")
-	losetup -d "$node"
-	exit 0
+
+        #In case the loopback is temporarily blocked, retry the losetup -d.
+        for i in 1 2 3 4 5
+        do
+          if losetup -d "$node"
+          then
+            exit 0
+          fi
+          sleep 1
+        done
+        log err "losetup -d $node failed."
+        exit 1
 	;;
 
       "")