From owner-freebsd-fs@FreeBSD.ORG Wed Oct 2 16:44:15 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 5DB06C60; Wed, 2 Oct 2013 16:44:15 +0000 (UTC) (envelope-from jmg@h2.funkthat.com) Received: from h2.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 25AA0273D; Wed, 2 Oct 2013 16:44:14 +0000 (UTC) Received: from h2.funkthat.com (localhost [127.0.0.1]) by h2.funkthat.com (8.14.3/8.14.3) with ESMTP id r92Gi8Ta094149 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 2 Oct 2013 09:44:08 -0700 (PDT) (envelope-from jmg@h2.funkthat.com) Received: (from jmg@localhost) by h2.funkthat.com (8.14.3/8.14.3/Submit) id r92Gi8Ak094148; Wed, 2 Oct 2013 09:44:08 -0700 (PDT) (envelope-from jmg) Date: Wed, 2 Oct 2013 09:44:08 -0700 From: John-Mark Gurney To: sbruno@freebsd.org Subject: Re: Endian issues, LE write to BE partitions Message-ID: <20131002164408.GB56872@funkthat.com> References: <1380730546.1619.47.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1380730546.1619.47.camel@localhost> User-Agent: Mutt/1.4.2.3i X-Operating-System: FreeBSD 7.2-RELEASE i386 X-PGP-Fingerprint: 54BA 873B 6515 3F10 9E88 9322 9CB1 8F74 6D3F A396 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.2 (h2.funkthat.com [127.0.0.1]); Wed, 02 Oct 2013 09:44:08 -0700 (PDT) Cc: freebsd-fs@freebsd.org X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 02 Oct 2013 16:44:15 -0000 Sean Bruno wrote this message on Wed, Oct 02, 2013 at 09:15 -0700: > Using makefs from an amd64 host to build a f/s in a VTOC8 partition will > destroy the entire partition table. I simplified the test to simple dd > to an existing partition and got the same result, exonerating mkfs > > I suspect a lack of endian knowledge in geom itself, not > geom_part_vtoc8. > > test case: > using amd64 host (10.0 current) create monolothic image > truncate -s+5G /var/tmp/myfile.img > mdconfig -f /var/tmp/myfile.img > build and load geom_part_vtoc8 kernel module > use gpart to create VTOC8 part table > add partition to part table to yeild the following: > > => 0 10442250 md0 VTOC8 (5.0G) > 0 10442250 1 freebsd-ufs (5G) This looks like a user error, or an issue that VTOC allows you to create/write to a partition that covers the label metadata... So this is most definately a VTOC8 issue... VTOC8 should at least return an error when trying to write sectors that contain it's metadata.. newfs actually skips the first few KB of the disk because bsdlabels would do the same thing... This sounds like makefs is writing to the first few KB of the disk unlike newfs which probably doesn't (because it knows it might be on a partitioned disk and could destroy the partition table)... > dd to md0a from dev zero for just a bit > dd if=/dev/zero of=/dev/md0a bs=64k count=100 > > destroy md0 via mdconfig -d -u 0 > recreate it with mdconfig -f /var/tmp/myfile.img > > gpart displays no partions for the image any more: > gpart: No such geom: md0. > > bcc freebsd-geom -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."