From owner-freebsd-current Sun Jan 25 15:47:48 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id PAA02550 for current-outgoing; Sun, 25 Jan 1998 15:47:48 -0800 (PST) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from smtp01.primenet.com (smtp01.primenet.com [206.165.6.131]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id PAA02544; Sun, 25 Jan 1998 15:47:37 -0800 (PST) (envelope-from tlambert@usr02.primenet.com) Received: (from daemon@localhost) by smtp01.primenet.com (8.8.8/8.8.8) id QAA23364; Sun, 25 Jan 1998 16:47:36 -0700 (MST) Received: from usr02.primenet.com(206.165.6.202) via SMTP by smtp01.primenet.com, id smtpd023357; Sun Jan 25 16:47:33 1998 Received: (from tlambert@localhost) by usr02.primenet.com (8.8.5/8.8.5) id QAA17876; Sun, 25 Jan 1998 16:47:31 -0700 (MST) From: Terry Lambert Message-Id: <199801252347.QAA17876@usr02.primenet.com> Subject: Re: stable current? To: dyson@FreeBSD.ORG Date: Sun, 25 Jan 1998 23:47:31 +0000 (GMT) Cc: scottm@cs.ucla.edu, freebsd-current@FreeBSD.ORG In-Reply-To: <199801251803.NAA25960@dyson.iquest.net> from "John S. Dyson" at Jan 25, 98 01:03:42 pm X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk > > For UNI kernels, John's latest round of vm changes seem to be more > > stable -- OTOH I'm not really pushing things that hard either. > > Rather than announcing the system is "better", I have been holding > out until someone else sees it. The only thing(s) that shouldn't > be working are the layered filesystems. Those thing(s) are really > broken, and absolutely no Lite/2 derivative has them working properly. > > Because of the structure of the merged VM/Buffer cache, we haven't had them > working for, a long time but now at least we have a better chance of someone > fixing them. That's not the only problem; I've identified most of them at one time or another... Were you out here (Bay Area) last Thursday for McKusick's talk at Network Appliance on FS stacking? I didn't go to that one, but I talked to him for about half an hour about a month ago, and he seemed to agree with most of what I identified (plus added a thing or two that I hadn't thought of before). The single biggest problem has *got* to be alias buffers hung off top and bottom vnodes in a stack. The vop_getpages/vop_putpages interface needs to become mandatory for all FS's. No more sneaking around it in the vnode pager. That should solve most of the nullfs and single-layer stack FS problems up front, so long as you don't expect locking to work. A real fix will require a VOP to ask for the backing vnode where the buffers and locks are hung off of; until then, I don't think unionfs has a chance of being safe to use. Terre Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.