From owner-freebsd-hackers@FreeBSD.ORG Tue Jan 23 18:30:18 2007 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id E935916A405 for ; Tue, 23 Jan 2007 18:30:14 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from turion.vk2pj.dyndns.org (c220-239-3-125.belrs4.nsw.optusnet.com.au [220.239.3.125]) by mx1.freebsd.org (Postfix) with ESMTP id DDD1313C4A6 for ; Tue, 23 Jan 2007 18:30:13 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from turion.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1]) by turion.vk2pj.dyndns.org (8.13.8/8.13.8) with ESMTP id l0NIUCFf003528; Wed, 24 Jan 2007 05:30:12 +1100 (EST) (envelope-from peter@turion.vk2pj.dyndns.org) Received: (from peter@localhost) by turion.vk2pj.dyndns.org (8.13.8/8.13.8/Submit) id l0NIUBcV003527; Wed, 24 Jan 2007 05:30:11 +1100 (EST) (envelope-from peter) Date: Wed, 24 Jan 2007 05:30:11 +1100 From: Peter Jeremy To: perryh@pluto.rain.com Message-ID: <20070123183011.GK838@turion.vk2pj.dyndns.org> References: <20070119201935.GA60202@x12.dk> <20070120024614.E99400@odysseus.silby.com> <20070122083727.GA61615@qlovarnika.bg.datamax> <45b5027e.g8Hs/VOZs+63TD6V%perryh@pluto.rain.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="H1spWtNR+x+ondvy" Content-Disposition: inline In-Reply-To: <45b5027e.g8Hs/VOZs+63TD6V%perryh@pluto.rain.com> X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.13 (2006-08-11) Cc: vd@freebsd.org, xride@x12.dk, freebsd-hackers@freebsd.org Subject: Re: Where to start? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Jan 2007 18:30:19 -0000 --H1spWtNR+x+ondvy Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, 2007-Jan-22 10:29:18 -0800, perryh@pluto.rain.com wrote: >I would guess that if a way could be found to preallocate the >journal space (as with mkfile(8) in sufficiently-old systems), mkfile(8)ing a journal is easy. This would not guarantee that the journal was a contiguous block though and the journalling code would also need to be able to follow the journal contents through a block list chain defined by an inode - this is not difficult but not as easy as having a single contiguous chunk of space. >and then record its location in a reasonably-secure location >(the superblock?), it could be accessed during recovery without >reference to possibly-corrupt filesystem metadata. The superblock is the logical location. There are a number of spare fields in the superblock that could potentially be used to contain a journal location. Files within UFS are described by an inode number so the 'location' of the journal would be an inode number. The journal code would need to verify that the given inode was internally consistent before it accessed the data. --=20 Peter Jeremy --H1spWtNR+x+ondvy Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) iD8DBQFFtlQz/opHv/APuIcRAiR2AKC3t9oe1OIsq35XmnW/2CXxcEUMigCfYyeD nK/VH0J2Y9tSztdjW96jooM= =2iwc -----END PGP SIGNATURE----- --H1spWtNR+x+ondvy--