From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 3 Jan 2002 19:25:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 3 Jan 2002 19:24:51 -0500 Received: from h24-64-71-161.cg.shawcable.net ([24.64.71.161]:31225 "EHLO lynx.adilger.int") by vger.kernel.org with ESMTP id ; Thu, 3 Jan 2002 19:24:46 -0500 Date: Thu, 3 Jan 2002 17:24:36 -0700 From: Andreas Dilger To: Vijay Kumar Cc: linux-kernel@vger.kernel.org Subject: Re: kernel patch support large fat partitions Message-ID: <20020103172436.I12868@lynx.no> Mail-Followup-To: Vijay Kumar , linux-kernel@vger.kernel.org In-Reply-To: <5.1.0.14.0.20020103152205.039f2008@mage.qualcomm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.4i In-Reply-To: <5.1.0.14.0.20020103152205.039f2008@mage.qualcomm.com>; from jkumar@qualcomm.com on Thu, Jan 03, 2002 at 03:42:20PM -0800 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 Jan 03, 2002 15:42 -0800, Vijay Kumar wrote: > This limitation is imposed by the data structures used by the linux fat > implementation to read/write directory entries. A 'long' data type is used > to access directory entries on the disk, of which only 28 bits are used to > identify the sector that contains the directory entry and the rest 4 bits > are used to specify offset of the directory entry inside the sector. Using > 28 bits to identify a sector means we cannot access sectors beyond 128GB > (2^28*512), thus limiting us from creating partitions larger than 128GB on > large disk drives. Some minor notes on your patch: 1) It appears you are running an editor with 4-space tabs, and as a result it has broken the indentation of some of your changes. This is easily seen when looking at the patch. 2) It is almost certainly wrong to use "loff_t" for an inode number. Maybe you could use "u64" instead? I also think that using "long long" explicitly is frowned upon. > I have made changes to fat, vfat and msdos file system implementations in > the kernel to use larger data types, thus allowing us to create larger > partitions. As per the GPL I would like to make the patch available to > everyone and also in case somebody has run into the same problem(who cares > about fat in the linux world). The patch has been fairly well tested only > on our systems(p3, 700MHz with FC). I truly appreciate if you & anybody in > the kernel mailing list have any feedback about the changes. Does this change the on-disk format for FAT at all, or is it merely a kernel filesystem code issue? I think only the latter, but best to check. Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/