From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262562AbTJNPNj (ORCPT ); Tue, 14 Oct 2003 11:13:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262569AbTJNPNj (ORCPT ); Tue, 14 Oct 2003 11:13:39 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:36545 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S262562AbTJNPNh (ORCPT ); Tue, 14 Oct 2003 11:13:37 -0400 Date: Tue, 14 Oct 2003 17:12:30 +0200 From: Jens Axboe To: Andi Kleen Cc: Andi Kleen , linux-kernel@vger.kernel.org Subject: Re: [PATCH] ide barrier support, #2 Message-ID: <20031014151230.GS1107@suse.de> References: <20031014125723.GR1107@suse.de> <20031014150807.GA99122@colin2.muc.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20031014150807.GA99122@colin2.muc.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 14 2003, Andi Kleen wrote: > > Uh be careful! It must be WRITEBARRIER, not WRITESYNC. I think I'll kill > > WRITEBARRIER and just call it WRITESYNC, it's more logical. I've added > > the modified variant, thanks. > > Why? The journaling just checks if the write finished and then submits > the dependent writes. It doesn't care about reordering. See the patch, WRITESYNC is used solely internally in raid1. WRITEBARRIER is a bitmask of BIO_RW and BIO_RW_BARRIER and that is what you want. I'll make that more clear. Writes will not be reordered around the barrier either, btw. > As long as WRITESYNC guarantees that the data hit disk when completed > then it should be ok. Yep. -- Jens Axboe