From owner-freebsd-current Mon Mar 20 13:57:36 2000 Delivered-To: freebsd-current@freebsd.org Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.40.131]) by hub.freebsd.org (Postfix) with ESMTP id 7842E37B95E for ; Mon, 20 Mar 2000 13:57:30 -0800 (PST) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (localhost.freebsd.dk [127.0.0.1]) by critter.freebsd.dk (8.9.3/8.9.3) with ESMTP id WAA21292; Mon, 20 Mar 2000 22:57:08 +0100 (CET) (envelope-from phk@critter.freebsd.dk) To: Matthew Dillon Cc: Julian Elischer , current@FreeBSD.ORG Subject: Re: B_WRITE cleanup patch, please test! In-reply-to: Your message of "Mon, 20 Mar 2000 13:29:51 PST." <200003202129.NAA71883@apollo.backplane.com> Date: Mon, 20 Mar 2000 22:57:08 +0100 Message-ID: <21290.953589428@critter.freebsd.dk> From: Poul-Henning Kamp Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG In message <200003202129.NAA71883@apollo.backplane.com>, Matthew Dillon writes: > I think the biggest win in regards to being able to arbitrarily stack > devices is to NOT attempt to forward struct buf's between devices when > non-trivial manipulation is required, and instead to make struct buf's > cheap enough that a device can simply allocate a new one and copy the > appropriate fields. > > In particular I really hate all the various b_*blkno fields. b_lblkno, > b_blkno, and b_pblkno. It is precisely due to the existance of these > hacks that arbitrary device stacking is difficult. This is basically what the stuff I'm doing addresses. -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message