From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262323AbVF2Bdi (ORCPT ); Tue, 28 Jun 2005 21:33:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262234AbVF2B3y (ORCPT ); Tue, 28 Jun 2005 21:29:54 -0400 Received: from free.hands.com ([83.142.228.128]:1185 "EHLO free.hands.com") by vger.kernel.org with ESMTP id S261191AbVF2B2h (ORCPT ); Tue, 28 Jun 2005 21:28:37 -0400 Date: Wed, 29 Jun 2005 02:37:31 +0100 From: Luke Kenneth Casson Leighton To: Grzegorz Kulewski Cc: linux-kernel@vger.kernel.org Subject: Re: accessing loopback filesystem+partitions on a file Message-ID: <20050629013731.GF9566@lkcl.net> References: <20050628233335.GB9087@lkcl.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org oh, bugger :) xen guest OSes manage it fine - the xen layer provides a means to present any block device as a "disk". that loopback filesystems cannot be presented as block devices by the linux kernel (with no involvement of xen) seems to be a curious omission. ... loopbackblock.ko, anyone? btw the [as yet formally-unannounced] project is at http://hands.com/d-i. try the xen0 install and then follow the instructions for creating a guest domain [by booting debian installer in a guest domain, as opposed to running debootstrap, the "normal" xen recommended method]. fortunately, phil has fixed the xen-guest-install, such that it completes successfully. that _still_ leaves a hard-disk-with-its-partitions in an actual LVM partition which is totally inaccessible. okay - i _say_ inaccessible: there is always the possibility of finding a spare hard drive, and then doing "dd if=/dev/vg/xen0hda of=/dev/hdd". this being 2005 last time i checked, it does seem to me to be a rather large waste of a) an entire hard drive b) time spent copying. *sigh*. sadly, answers on back of envelope ideally need to involve a tool or procedure of some sort that can be run by dummies such as myself on a regular basis without fear of major-cock-up, rather than something [ending oh say in .pl] that stands a good chance of being exorcised [or exercised] as voodoo witchcraft. unmitigated steaming "perl" advocates need not respond. please. l. On Wed, Jun 29, 2005 at 02:35:25AM +0200, Grzegorz Kulewski wrote: > On Wed, 29 Jun 2005, Luke Kenneth Casson Leighton wrote: > > >[if you are happy to reply at all, please reply cc'd thank you.] > > > >hi, > > > >i'm really sorry to be bothering people on this list but i genuinely > >don't what phrases to google for what i am looking for without getting > >swamped by useless pages, which you will understand why when you see > >the question, below. > > > >the question is, therefore: > > > > * how the hell do you loopback mount (or lvm mount > > or _anything_! something!) partitions that have > > been created in a loopback'd file!!!! > > > > [aside from booting up a second pre-installed xen > > guest domain and making the filesystem-in-a-file > > available as /dev/hdb of course.] > > > >answers of the form "work out where the partitions are, then use > >hexedit to remove the first few blocks" will win no prizes here. > > The bad news: it was impossible (or at least very hard to do). > > The good news: it is possible now. The anwser is: > - figure where the partitions are (possibly using some simple script), > - use device-mapper to create block devices covering partitions, > - mount them. > > I do not know if this anwser will win your price but it is IMHO far better > than hexedit... :-) And probably this is the only anwser. > > (IIRC if you have one partition you can skip partition table with offset > option to losetup. But this will only work in this special case...) > > > Grzegorz Kulewski > -- -- http://lkcl.net --