From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751049AbWF2RYc (ORCPT ); Thu, 29 Jun 2006 13:24:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751079AbWF2RYb (ORCPT ); Thu, 29 Jun 2006 13:24:31 -0400 Received: from mail.clusterfs.com ([206.168.112.78]:19917 "EHLO mail.clusterfs.com") by vger.kernel.org with ESMTP id S1751049AbWF2RYb (ORCPT ); Thu, 29 Jun 2006 13:24:31 -0400 Date: Thu, 29 Jun 2006 10:30:45 -0600 From: Andreas Dilger To: Takashi Sato Cc: Johann Lombardi , ext2-devel@lists.sourceforge.net, cmm@us.ibm.com, linux-kernel@vger.kernel.org Subject: Re: [Ext2-devel] [RFC 1/2] ext3: enlarge blocksize and fix rec_lenoverflow Message-ID: <20060629163045.GA5318@schatzie.adilger.int> Mail-Followup-To: Takashi Sato , Johann Lombardi , ext2-devel@lists.sourceforge.net, cmm@us.ibm.com, linux-kernel@vger.kernel.org References: <20060628202421.GL5318@schatzie.adilger.int> <04d401c69b69$581db0d0$4168010a@bsd.tnes.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <04d401c69b69$581db0d0$4168010a@bsd.tnes.nec.co.jp> User-Agent: Mutt/1.4.1i X-GPG-Key: 1024D/0D35BED6 X-GPG-Fingerprint: 7A37 5D79 BF1B CECA D44F 8A29 A488 39F5 0D35 BED6 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Jun 29, 2006 19:46 +0900, Takashi Sato wrote: > >On Jun 28, 2006 17:50 +0200, Johann Lombardi wrote: > >>ext2/ext3_dir_entry_2 has a 16-bit entry(rec_len) and it would overflow > >>with 64KB blocksize. This patch prevent from overflow by limiting > >>rec_len to 65532. > > > >Having a max rec_len of 65532 is rather unfortunate, since the dir > >blocks always need to filled with dir entries. > > Oh, that's right. > > >65536 - 65532 = 4, and > >the minimum ext3_dir_entry size is 8 bytes. I would instead make this > >maybe 64 bytes less so that there is room for a filename in the "tail" > >dir_entry. > > What does "64 bytes" mean? > Do you mean that the following dummy entry should be added > at the tail of the directory block? > > struct ext3_dir_entry_2 { > __le32 inode = 0 > __le16 rec_len = 16 > __u8 name_len = 4 > __u8 file_type = 0 > char name = "dir_end" > }; Sure, something like this. The goal of this dir entry is to: a) fill up the remaining space in the dir block b) be large enough to be used later on when the start of the block has been consumed, so it shouldn't be too small. It could even be as large as 4kB or 8kB or 32kB. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.