From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Sachin Gaikwad" Subject: Re: Upgrading datastructures between different filesystem versions Date: Wed, 26 Sep 2007 18:29:19 -0500 Message-ID: References: <7e77a4050709250827p26683c6bqc65832783ba1c365@mail.gmail.com> <46F9F0EB.6020404@gmail.com> <20070926161756.GU32520@schatzie.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: "Jim Cromie" , "kernel learner" , linux-fsdevel@vger.kernel.org, kernelnewbies@nl.linux.org Return-path: Received: from nf-out-0910.google.com ([64.233.182.190]:31472 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751726AbXIZX3W (ORCPT ); Wed, 26 Sep 2007 19:29:22 -0400 Received: by nf-out-0910.google.com with SMTP id g13so2102784nfb for ; Wed, 26 Sep 2007 16:29:20 -0700 (PDT) In-Reply-To: <20070926161756.GU32520@schatzie.adilger.int> Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 9/26/07, Andreas Dilger wrote: > On Sep 25, 2007 23:40 -0600, Jim Cromie wrote: > > kernel learner wrote: > > >ext3 filesystem has 32-bit block address and ext4 filesystem has > > >48-bit block address. If a user installs ext4, how will the file > > >system handle already existing block with 32 bit values? > > > > Why should it ? thats what ext3 is for. > > Bzzt. Wrong answer. The ext4 code will be able to read existing ext3 > (and ext2) filesystems just fine. Otherwise there wouldn't be much > of an upgrade path. > > > Id expect ext4 drivers handling ext3 filesystems is a distant, secondary > > goal to getting a fast, reliable, clean 48bit filesystem working. > > Far from the truth. One of the main goals of ext4 is that it is a drop-in > replacement for ext3. The code is mostly incremental improvements over > ext3, and that IS one of the reasons that it is reliable. We didn't throw > away 10 years of bug fixes in the ext2/ext3 code when adding the ext4 > features. > > Cheers, Andreas > -- > Andreas Dilger > Principal Software Engineer > Cluster File Systems, Inc. > > > -- > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to ecartis@nl.linux.org > Please read the FAQ at http://kernelnewbies.org/FAQ > > Is it not the case that VFS takes care of all filesystems available ? VFS will see if a particular file belongs to ext3 or ext4 and call that FS's drivers to access information ?? Correct me if I am wrong. I am a newbie! Sachin