From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756827Ab0EXKvx (ORCPT ); Mon, 24 May 2010 06:51:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:17969 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756017Ab0EXKvw (ORCPT ); Mon, 24 May 2010 06:51:52 -0400 Message-ID: <4BFA5A3F.4040005@redhat.com> Date: Mon, 24 May 2010 13:51:43 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: Nick Piggin CC: Cesar Eduardo Barros , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] mm: Swap checksum References: <4BF81D87.6010506@cesarb.net> <1274551731-4534-3-git-send-email-cesarb@cesarb.net> <4BF94792.5030405@redhat.com> <4BF97AC2.1040505@cesarb.net> <4BFA1F92.2080802@redhat.com> <20100524073259.GW2516@laptop> In-Reply-To: <20100524073259.GW2516@laptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/24/2010 10:32 AM, Nick Piggin wrote: > > I wonder, though. If we no longer trust block devices to give the > correct data back, should we provide a meta block device to do error > detection? Some block devices do provide space for end-to-end checksums. For the ones that don't, I see no efficient way of adding it (either we turn one access into two, or we have a non-power-of-two block size). > No production filesystem on Linux has checksums (well, ext4 > has a few). Of the ones that add checksumming, I'd say most will not do > data checksumming (and for direct IO it is not done). > I believe btrfs checksums direct IO. Unfortunately it has some way to go before it can be used in production. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.