From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262118AbTLDEAN (ORCPT ); Wed, 3 Dec 2003 23:00:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262188AbTLDEAN (ORCPT ); Wed, 3 Dec 2003 23:00:13 -0500 Received: from neon-gw-l3.transmeta.com ([63.209.4.196]:49415 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id S262118AbTLDEAH (ORCPT ); Wed, 3 Dec 2003 23:00:07 -0500 To: linux-kernel@vger.kernel.org From: "H. Peter Anvin" Subject: Re: partially encrypted filesystem Date: 3 Dec 2003 19:59:47 -0800 Organization: Transmeta Corporation, Santa Clara CA Message-ID: References: <1070485676.4855.16.camel@nucleon> <20031203214443.GA23693@wohnheim.fh-wedel.de> <3FCE8CF5.4030006@pobox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Disclaimer: Not speaking for Transmeta in any way, shape, or form. Copyright: Copyright 2003 H. Peter Anvin - All Rights Reserved Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Followup to: <3FCE8CF5.4030006@pobox.com> By author: Jeff Garzik In newsgroup: linux.dev.kernel > > Linus Torvalds wrote: > > With an encrypted filesystem, you can't do that. Or rather: you can do it > > if the filesystem is read-only, but you definitely CANNOT do it on > > writing. For writing you have to marshall the output buffer somewhere > > else (and quite frankly, it tends to become a lot easier if you can do > > that for reading too). > > > > And that in turn causes problems. You get all kinds of interesting > > deadlock schenarios when write-out requires more memory in order to > > succeed. So you need to get careful. Reading ends up being the much easier > > case (doesn't have the same deadlock issues _and_ you could do it in-place > > anyway). > > > FWIW zisofs and ntfs have to do this too, since X on-disk compressed > pages must be expanded to X+Y in-memory pages... > zisofs is read-only, so it doesn't apply. -hpa -- at work, in private! If you send me mail in HTML format I will assume it's spam. "Unix gives you enough rope to shoot yourself in the foot." Architectures needed: ia64 m68k mips64 ppc ppc64 s390 s390x sh v850 x86-64