From owner-freebsd-stable@FreeBSD.ORG Tue May 10 22:16:22 2005 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6593B16A4CE for ; Tue, 10 May 2005 22:16:22 +0000 (GMT) Received: from natco3.natcotech.com (natco3.natcotech.com [205.167.142.103]) by mx1.FreeBSD.org (Postfix) with ESMTP id A017043D62 for ; Tue, 10 May 2005 22:16:19 +0000 (GMT) (envelope-from billy@nlcc.us) Received: from ibm.nlcc.us (ldhl-ras1-dial-12-28-24-127.natcotech.com [12.28.24.127]) by natco3.natcotech.com (Postfix) with ESMTP id 4DE6D62B32 for ; Tue, 10 May 2005 17:16:18 -0500 (CDT) Received: (qmail 83697 invoked by uid 89); 10 May 2005 22:16:17 -0000 Received: from unknown (HELO ?192.168.0.2?) (billy@192.168.0.2) by ibm.nlcc.us with SMTP; 10 May 2005 22:16:17 -0000 Message-ID: <428132B0.4060104@nlcc.us> Date: Tue, 10 May 2005 17:16:16 -0500 From: Billy Newsom User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7) Gecko/20040616 X-Accept-Language: en-us, en MIME-Version: 1.0 To: freebsd-stable@freebsd.org References: <4280353B.8050306@leadhill.net> <42803B66.3070200@alumni.rice.edu> <428044C2.80208@leadhill.net> <428052CB.2000704@alumni.rice.edu> In-Reply-To: <428052CB.2000704@alumni.rice.edu> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: nfs bug & df: Can I lock up my kernel and overflow this buffer? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 May 2005 22:16:22 -0000 Jonathan Noack wrote: >> Anyone tried that sort of stuff in fstab? I'm a little skeptical. > > I use "that sort of stuff" and have for a long time. Here's one of my > fstab lines: > > optimator:/usr/home /usr/home nfs rw,-3,-T,-r=32768,-w=32768 0 0 > > It's obvious you don't believe me but why are you unwilling to try it > yourself? Well, because this fails to work on the commandline: #mount -o -s -x 2 -T dell:/nfs /dellbak I tried tons of different ways, never could get mount to do that, so I gave up on fstabbing options. Since the above mount command wouldn't even work, I figured I could forget about putting those same options (which mount calls illegal) in the fstab file. That's where the man pages only go so far. Without the examples you give, I was pretty sure that it was pointless to get fstab options to do what mount wouldn't. What it boils down to is that mount is fine with these options in fstab, but barfs when doing them on the commandline. That was so couter-intuitive, I went around it for the sake of getting things done. FreeBSD man pages are nice and all, but without a textbook siting by with some examples, it can be difficult. I learned Unix pretty much ad hoc, so I find that examples (such as you gave) are worth much more than man pages now that I know most of the basics. Thanks. But what I did discover is that if I mount the same nfs resource multiple times, I get multiple, identical mounts (using fstab options, or commandline, either one). I have to umount each one serially. How is this a feature? What good does it do me if I mount the same nfs drive to the same place n times? Won't that eventually cause a deadlock as n increases beyond a few hundred or thousand? -- especially when the NFS server goes down? Shouldn't the second and subsequent mounts either fail or not be attempted due to a sanity check? #mount /usr mount: /dev/ad0s1f: Device busy Exit 1 That seems reasonable for /usr. But as I stated before, NFS resources nevere apparently become "busy", and there is no sanity check to prevent mulitiple simultaneous mounts of identical file systems on identical file trees.