From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH] extend e2fsprogs functionality to add EXT2_FLAG_DIRECT option Date: Tue, 12 Jan 2010 07:23:19 -0500 Message-ID: <20100112122319.GA20596@infradead.org> References: <4B46FCB2.1090308@redhat.com> <4B4B84E2.1050508@redhat.com> <4B4C54DC.4040006@redhat.com> <4B4C6429.6090803@redhat.com> <4B4C67F5.1020009@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ric Wheeler , linux-ext4@vger.kernel.org, Christoph Hellwig To: Michal Novotny Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:40618 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750917Ab0ALMXU (ORCPT ); Tue, 12 Jan 2010 07:23:20 -0500 Content-Disposition: inline In-Reply-To: <4B4C67F5.1020009@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jan 12, 2010 at 01:15:49PM +0100, Michal Novotny wrote: > I don't really know if I see your point but the thing here is that there > was no way to open a file directly (ie. using O_DIRECT). The direct > write support has been added only to make it possible to use both read > and write directly. The main reason to create this patch was to add > direct read support and flush capability won't help me at all. I am > working in Red Hat, Virtualization team on Xen so I am really not that > much familiar with file systems but what I needed was an option to read > the data directly (using O_DIRECT) in e2fsprogs. One bug was about > pygrub (Python version of GRUB of Xen PV guests that is internally using > e2fsprogs functionality to access data on ext2/3/4 partition to boot the > PV guests) uses outdated/cached data so some modifications were > necessary to open everything directly... So to get things staigt: you're using e2fsprogs to manipulate a life filesystem and thing using O_DIRECT saves your ass? I think you need to rething your model of operation fundamentally in that case.