From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265378AbTLHL2a (ORCPT ); Mon, 8 Dec 2003 06:28:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265380AbTLHL2a (ORCPT ); Mon, 8 Dec 2003 06:28:30 -0500 Received: from pentafluge.infradead.org ([213.86.99.235]:10393 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S265378AbTLHL22 (ORCPT ); Mon, 8 Dec 2003 06:28:28 -0500 Subject: Re: partially encrypted filesystem From: David Woodhouse To: Phillip Lougher Cc: =?ISO-8859-1?Q?J=F6rn?= Engel , Kallol Biswas , linux-kernel@vger.kernel.org, "linux-fsdevel@vger.kernel.org" In-Reply-To: <3FCF7AD5.4050501@lougher.demon.co.uk> References: <1070485676.4855.16.camel@nucleon> <20031203214443.GA23693@wohnheim.fh-wedel.de> <20031204141725.GC7890@wohnheim.fh-wedel.de> <20031204172653.GA12516@wohnheim.fh-wedel.de> <3FCF7AD5.4050501@lougher.demon.co.uk> Content-Type: text/plain Message-Id: <1070882901.31993.72.camel@hades.cambridge.redhat.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 (1.4.5-8.dwmw2.1) Date: Mon, 08 Dec 2003 11:28:22 +0000 Content-Transfer-Encoding: 7bit X-SA-Exim-Mail-From: dwmw2@infradead.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Pentafluge-Mail-From: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2003-12-04 at 18:20 +0000, Phillip Lougher wrote: > Considering that Jffs2 is the only writeable compressed filesystem, yes. > What should be borne in mind is compressed filesystems never expect > the data after compression to be bigger than the original data. In fact that assumption is fairly trivial to remove, if you can put an upper bound on the growth. Adding encryption of data to JFFS2 would actually be fairly trivial; encryption of metadata would be harder. You could do it without touching or grokking the core of JFFS2 at all -- just poke at fs/jffs2/compr.c and note that you're expected to eat as much of the input as will fit into the output buffer, returning success even if it didn't all fit. -- dwmw2