From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Novotny Subject: Re: [PATCH] extend e2fsprogs functionality to add EXT2_FLAG_DIRECT option Date: Tue, 12 Jan 2010 11:54:20 +0100 Message-ID: <4B4C54DC.4040006@redhat.com> References: <4B46FCB2.1090308@redhat.com> <4B4B84E2.1050508@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: Ric Wheeler Return-path: Received: from mx1.redhat.com ([209.132.183.28]:35856 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753951Ab0ALKym (ORCPT ); Tue, 12 Jan 2010 05:54:42 -0500 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o0CAsghJ026154 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 12 Jan 2010 05:54:42 -0500 In-Reply-To: <4B4B84E2.1050508@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 01/11/2010 09:06 PM, Ric Wheeler wrote: > On 01/08/2010 04:36 AM, Michal Novotny wrote: >> This patch extends functionality of e{2|4}fsprogs to add >> EXT2_FLAG_DIRECT flag to be passed to ext2fs_open2() function. This >> internally calls open() function with O_DIRECT and handles the memory >> alignment for both read and write operations. >> In some cases direct access to devices is necessary and that was the >> main reason for this patch to be done. >> >> The main reason why this was done is that pygrub (used by xen >> virtualization user-space package, it's a python version of grub for >> paravirtualized guests) sometimes uses outdated version of grub.conf >> file. Modifications to xen package were *not* enough because >> e2fsprogs doesn't open the files directly. That's why I added >> EXT2_FLAG_DIRECT support to make read/write operations work directly >> when passed. It's been tested with pygrub like mentioned above for >> read operation and it's working fine. >> >> Signed-off-by: Michal Novotny > > Can you add to this some kind of data flow overview? Seems like a > really odd way to update this file system... > > ric > What do you mean by adding some kind of data flow overview? I am not working on file systems but I needed option open files directly to be added to e2fsprogs to make pygrub working right with not using cached/outdated data so this was the first patch I did for file system so I don't realy know what do you mean by data flow overview ... Thanks, Michal