From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756376AbZEICZj (ORCPT ); Fri, 8 May 2009 22:25:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751614AbZEICZa (ORCPT ); Fri, 8 May 2009 22:25:30 -0400 Received: from wf-out-1314.google.com ([209.85.200.172]:44899 "EHLO wf-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751573AbZEICZa (ORCPT ); Fri, 8 May 2009 22:25:30 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type :content-transfer-encoding; b=Q8Dw7tYNIOM2/UtxdxY7w6puOr1sN/HuuXQnfE1OAAJQ5pLa4V246fl9ewXOxp1W45 0gwhjBVwt2KwvTY21v4t+j25s9+8jJirpFtvZZwr/ya9b0WYRnIdxxzc0ONATwGz+K0t A1ZJ31PzaSOJnF5T/Z8vQUgXxJhPZMS8R6B98= MIME-Version: 1.0 Date: Sat, 9 May 2009 10:25:29 +0800 Message-ID: Subject: Can I/O order be guaranteed by submitting sycn bio From: =?GB2312?B?0Lu42Q==?= To: linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Some journal file systems submits sycn bio to do ordered write if the device does not support barrier i/o. But the sync bio only implies the unplug of the request queue. Some elevators may reorder the request. It's seems that the bio only with BIO_RW_SYNC flag could not guarantee the write order. Is this true? If so, is there any better way to do ordered write when there is no barrier i/o support. Thanks, -- Xie Gang