From: Andrew Morton Subject: Re: [PATCH 2/2] ext2: Avoid rec_len overflow with 64KB block size Date: Wed, 17 Oct 2007 21:09:25 -0700 Message-ID: <20071017210925.c3c66de5.akpm@linux-foundation.org> References: <20070828190551.415127746@sgi.com> <20070828190735.292638294@sgi.com> <1188432669.3799.35.camel@localhost.localdomain> <1188434857.3799.76.camel@localhost.localdomain> <1191285346.11737.58.camel@localhost.localdomain> <20071004131207.65406a7b.akpm@linux-foundation.org> <20071011111849.GC7125@duck.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: cmm@us.ibm.com, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, sho@tnes.nec.co.jp, clameter@sgi.com To: Jan Kara Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:49110 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750990AbXJREJc (ORCPT ); Thu, 18 Oct 2007 00:09:32 -0400 In-Reply-To: <20071011111849.GC7125@duck.suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Thu, 11 Oct 2007 13:18:49 +0200 Jan Kara wrote: > With 64KB blocksize, a directory entry can have size 64KB which does not fit > into 16 bits we have for entry lenght. So we store 0xffff instead and convert > value when read from / written to disk. btw, this changes ext2's on-disk format. a) is the ext2 format documented anywhere? If so, that document will need updating. b) what happens when an old ext2 driver tries to read and/or write this directory entry? Do we need a compat flag for it? c) what happens when old and new ext3 or ext4 try to read/write this directory entry?