From owner-cvs-all@FreeBSD.ORG Wed Mar 10 22:30:38 2004 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0FF9716A4D1 for ; Wed, 10 Mar 2004 22:30:38 -0800 (PST) Received: from tx2.oucs.ox.ac.uk (tx2.oucs.ox.ac.uk [163.1.2.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5184B43D48 for ; Wed, 10 Mar 2004 22:30:37 -0800 (PST) (envelope-from colin.percival@wadham.ox.ac.uk) Received: from scan2.oucs.ox.ac.uk ([163.1.2.162] helo=localhost) by tx2.oucs.ox.ac.uk with esmtp (Exim 4.24) id 1B1JiG-0000Gh-KV for cvs-all@FreeBSD.org; Thu, 11 Mar 2004 06:30:36 +0000 Received: from rx2.oucs.ox.ac.uk ([163.1.2.161]) by localhost (scan2.oucs.ox.ac.uk [163.1.2.162]) (amavisd-new, port 25) with ESMTP id 00867-04 for ; Thu, 11 Mar 2004 06:30:36 +0000 (GMT) Received: from gateway.wadham.ox.ac.uk ([163.1.161.253]) by rx2.oucs.ox.ac.uk with smtp (Exim 4.24) id 1B1JiG-0000Ga-74 for cvs-all@FreeBSD.org; Thu, 11 Mar 2004 06:30:36 +0000 Received: (qmail 23055 invoked by uid 1004); 11 Mar 2004 06:30:35 -0000 Received: from colin.percival@wadham.ox.ac.uk by gateway by uid 71 with qmail-scanner-1.20 (clamscan: 0.67. sweep: 2.18/3.79. Clear:RC:1(163.1.161.131):. Processed in 0.529546 secs); 11 Mar 2004 06:30:35 -0000 Received: from dhcp1131.wadham.ox.ac.uk (HELO piii600.wadham.ox.ac.uk) (163.1.161.131) by gateway.wadham.ox.ac.uk with SMTP; 11 Mar 2004 06:30:34 -0000 Message-Id: <6.0.1.1.1.20040311062306.03f9ade0@imap.sfu.ca> X-Sender: cperciva@imap.sfu.ca (Unverified) X-Mailer: QUALCOMM Windows Eudora Version 6.0.1.1 Date: Thu, 11 Mar 2004 06:30:28 +0000 To: "Poul-Henning Kamp" From: Colin Percival In-Reply-To: <48203.1078985587@critter.freebsd.dk> References: <48203.1078985587@critter.freebsd.dk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed cc: cvs-src@FreeBSD.org cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/sys mdioctl.h src/sys/dev/md md.c src/sbin/mdconfig mdconfig.8 mdconfig.c X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Mar 2004 06:30:38 -0000 At 06:13 11/03/2004, Poul-Henning Kamp wrote: >That is a matter of taste more than anything else. A vnode backed md(4) >device is technically a layering violation, so either the syncer or >the md(4) code itself (or both) needs to be aware of the special case. Is it really necessary for vnode-backed memory disks to be accessed through the filesystem? Why can't md(4) hijack the disk blocks which constitute the file (telling the filesystem not to touch them, of course) and translate I/O operations directly into I/O on the underlying device? Colin Percival