From: "Aneesh Kumar K.V" Subject: Re: [PATCH] Add checks to validate extent entries. Date: Mon, 9 Feb 2009 16:01:58 +0530 Message-ID: <20090209103158.GD31884@skywalker> References: <20090207173239.GA25942@skywalker> <1234036882-30656-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <499004C4.9040305@ph.tum.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: tytso@mit.edu, linux-ext4@vger.kernel.org To: Thiemo Nagel Return-path: Received: from e23smtp09.au.ibm.com ([202.81.31.142]:51653 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754116AbZBIKcI (ORCPT ); Mon, 9 Feb 2009 05:32:08 -0500 Received: from d23relay01.au.ibm.com (d23relay01.au.ibm.com [202.81.31.243]) by e23smtp09.au.ibm.com (8.13.1/8.13.1) with ESMTP id n19APnwp021859 for ; Mon, 9 Feb 2009 21:25:49 +1100 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay01.au.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id n19AWN7T324056 for ; Mon, 9 Feb 2009 21:32:23 +1100 Received: from d23av01.au.ibm.com (loopback [127.0.0.1]) by d23av01.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n19AW5ZH017967 for ; Mon, 9 Feb 2009 21:32:05 +1100 Content-Disposition: inline In-Reply-To: <499004C4.9040305@ph.tum.de> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, Feb 09, 2009 at 11:26:12AM +0100, Thiemo Nagel wrote: > Aneesh Kumar K.V wrote: > > This patch adds check to validate the extent entries along > > with extent headers. Should handle crash with corrupt filesystem. > > While your patch probably decreases the average number of checks that > are done, it makes single random accesses quite expensive since always > complete extent blocks are checked at once, even if just a single pblock > is accessed. No idea whether there are workloads which have that as a > typical access pattern... The second patch make sure we do it only when we read the extent information from the disk. -aneesh