From owner-freebsd-scsi Sun Jul 13 10:03:08 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id KAA28424 for freebsd-scsi-outgoing; Sun, 13 Jul 1997 10:03:08 -0700 (PDT) Received: from cais.cais.com (root@cais.com [199.0.216.4]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id KAA28418 for ; Sun, 13 Jul 1997 10:03:02 -0700 (PDT) Received: from earth.mat.net (root@earth.mat.net [205.252.122.1]) by cais.cais.com (8.8.5/CJKv1.99-CAIS) with SMTP id MAA25612; Sun, 13 Jul 1997 12:49:02 -0400 (EDT) Received: from Journey2.mat.net (journey2.mat.net [205.252.122.116]) by earth.mat.net (8.6.12/8.6.12) with SMTP id MAA14637; Sun, 13 Jul 1997 12:49:00 -0400 Date: Sun, 13 Jul 1997 12:49:09 -0400 (EDT) From: Chuck Robey X-Sender: chuckr@Journey2.mat.net To: Simon Shapiro cc: freebsd-SCSI@FreeBSD.ORG, filo@yahoo.com, dg@root.com Subject: Re: problems with reboot In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-scsi@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk On Sat, 12 Jul 1997, Simon Shapiro wrote: > > Hi Chuck Robey; On 12-Jul-97 you wrote: > > ... > > > Is this always safe? I've had some instances where a umount call simply > > hung, and never returned. I think they were either nfs or msdos mounts > > that gave this trouble, but the umount call could not be kill'ed, and > > making shutdown wait? Would halt still work, as an emergency measure? > > I know the FSs that were hung wouldn't be closed, but at least my ufs FSs > > would be clean. > > Network Failure system is a special case (i AM being nice :-); > It is supposedly stateless and the mount is a client and thus not governing > physical I/O. a shutdown can (should) probably force a umount. Even on a > local system, a forced umount is OK. It is a FS issue. But if the fs > layer calls a function that by definition blocks, it is ``none of the > caller's business'' how/what the callee does and how long it takes. > To assume anything on the nature if a callee's internals is not a good > idea. Here we have a live exapmple (why it is a bad idea). I *think* the nfs failure was when I was learning how to correctly set up a 3C503 for NFS. Before I got that right, while experimenting, the second action on an mount going thru the 3C503 would hang, and a forcible umount would hang too. That was OK, I could just shut down the machine. I'm not sure here ... if your proposed fix would work on shutdown only, but allow a halt or reboot under emergency conditions, then I'm in agreement, and adding hooks to shutdown is a great path to take; if not, then you can see my objection here, right? ----------------------------+----------------------------------------------- Chuck Robey | Interests include any kind of voice or data chuckr@eng.umd.edu | communications topic, C programming, and Unix. 213 Lakeside Drive Apt T-1 | Greenbelt, MD 20770 | I run Journey2 and picnic, both FreeBSD (301) 220-2114 | version 3.0 current -- and great FUN! ----------------------------+-----------------------------------------------