From owner-freebsd-current Mon Dec 27 17:10:37 1999 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 4750114E13 for ; Mon, 27 Dec 1999 17:10:34 -0800 (PST) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.9.3/8.9.2) with ESMTP id CAA09893; Tue, 28 Dec 1999 02:10:24 +0100 (CET) (envelope-from phk@critter.freebsd.dk) To: Matthew Dillon Cc: freebsd-current@FreeBSD.ORG Subject: Re: Proposed patch to fix VN device (again) In-reply-to: Your message of "Mon, 27 Dec 1999 17:01:55 PST." <199912280101.RAA34874@apollo.backplane.com> Date: Tue, 28 Dec 1999 02:10:23 +0100 Message-ID: <9890.946343423@critter.freebsd.dk> From: Poul-Henning Kamp Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG In message <199912280101.RAA34874@apollo.backplane.com>, Matthew Dillon writes: > First, you are confusing the underlying swap devices that we swapon on > with the parent swap device that controls them. The parent swap device > needs to have a dev_t - it does not currently have one, and this is > the entry point that the buffers are going into. The underlying swap > devices *already* have a dev_t. My kernel crashes on a NULL bp->b_dev. > In fact, it also crashes on a NULL vp->v_rdev. And where in the code does this crash happen ? > Second, the clustering done above the VN device is done by the > filesystem and has no understanding of whether the underlying media > controlled by the VN device can itself be clustered in the same way. > When using swap as backing store what may appear to be clusterable > by the filesystem may actually *NOT* be clusterable when you get into > the swap device due to potentially non-contiguous mappings as well > as border-crossings between interleaved swap devices. So you need to cluster all the way through the VN device ? Obviously clustering on just one side will not buy you anything. Tough luck... It sounds more and more like the mistake here is for VN to have a specfs VOP vector on top, I think it needs its own VOP vector so it can get hold of the VOP_BMAP function... -- 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