Hi Zhengyuan, Thanks for your input. I will add your patch (as a separate patch) to my v2 set (coming soon). For your question, I think updating superblock every 5 second is OK. We sure can fix that if it becomes a concern. Thanks, Song >> On 9/24/16, 7:51 AM, "Zhengyuan Liu" <liuzhengyuang521@xxxxxxxxx> wrote: 100c221268fd893bfb35273ef9ba14994f38bc6c ��.n��������+%������w��{.n�����{����w��ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f