From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sven-Haegar Koch Subject: Re: [RFC 0/13] extents and 48bit ext3 Date: Sat, 10 Jun 2006 02:49:32 +0200 (CEST) Message-ID: References: <1149816055.4066.60.camel@dyn9047017069.beaverton.ibm.com> <20060609091327.GA3679@infradead.org> <20060609030759.48cd17a0.akpm@osdl.org> <44899653.1020007@garzik.org> <87irnab33v.fsf@graviton.dyn.troilus.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Jeff Garzik , Andrew Morton , Christoph Hellwig , cmm@us.ibm.com, linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org Return-path: Received: from mercury.sdinet.de ([193.103.161.30]:9880 "EHLO mercury.sdinet.de") by vger.kernel.org with ESMTP id S1030575AbWFJAtd (ORCPT ); Fri, 9 Jun 2006 20:49:33 -0400 To: Michael Poole In-Reply-To: <87irnab33v.fsf@graviton.dyn.troilus.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Fri, 9 Jun 2006, Michael Poole wrote: > Jeff Garzik writes: > >> Andrew Morton wrote: >>> Ted&co have been pretty good at avoiding compatibility problems. >> >> Well, extents and 48bit make that track record demonstrably worse. >> >> Users are now forced to remember that, if they write to their >> filesystem after using either $mmver or $korgver kernels, they are >> locked out of using older kernels. > > Users are also forced to remember that, if they use certain new > distros or programs, they are locked out of using older kernels. They > are forced to remember that if they have certain newer hardware, they > are locked out of using older kernels. They are forced to remember > that if they use ext3 (or XFS or JFS) _at all_ they are locked out of > using older kernels. Why single out this particular aspect of limited > forward compatibility to harp on so much? I see a different problem with "ext3 + extends is not ext3 anymore" when the feature goes mainstream: - user with old distri, no extends in use, no kernel support for them - user has some kind of problem - uses new rescue disk (aka knoppix at the time of problem) - that then is current stuff, and certainly uses extents - fixes problem on disk (may be a simple as running lilo/grub from chroot, happens often for me) - tries to boot back into his distri -> *boom* he lost c'ya sven -- The Internet treats censorship as a routing problem, and routes around it. (John Gilmore on http://www.cygnus.com/~gnu/)