From owner-freebsd-current@FreeBSD.ORG Tue May 13 09:56:15 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0130B37B401; Tue, 13 May 2003 09:56:15 -0700 (PDT) Received: from fledge.watson.org (fledge.watson.org [204.156.12.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3D9C143F3F; Tue, 13 May 2003 09:56:14 -0700 (PDT) (envelope-from robert@fledge.watson.org) Received: from fledge.watson.org (localhost [127.0.0.1]) by fledge.watson.org (8.12.9/8.12.9) with ESMTP id h4DGu4On082386; Tue, 13 May 2003 12:56:04 -0400 (EDT) (envelope-from robert@fledge.watson.org) Received: from localhost (robert@localhost)h4DGu4Zv082383; Tue, 13 May 2003 12:56:04 -0400 (EDT) (envelope-from robert@fledge.watson.org) Date: Tue, 13 May 2003 12:56:04 -0400 (EDT) From: Robert Watson X-Sender: robert@fledge.watson.org To: "Andrew P. Lentvorski, Jr." In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: Don Lewis cc: alfred@FreeBSD.org cc: current@FreeBSD.org Subject: Re: rpc.lockd spinning; much breakage X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 May 2003 16:56:15 -0000 On Tue, 13 May 2003, Andrew P. Lentvorski, Jr. wrote: > On Mon, 12 May 2003, Robert Watson wrote: > > > (3) Sometimes rpc.lockd on 5.x acting as a server gets really confused > > when you mix local and remote locks. > > Yes, don't do that. ;) Unfortunately, a common case I'm interested in is "mail spool on a mail server is NFS-exported to many clients", which bumps into locking between the client and server pretty quickly :-). > One problem is that FreeBSD doesn't allocate enough fields in its local > lock structure to distinguish external identifiers in the locks (all > locks look like they are owned by the rpc.lockd user). Consequently, > rpc.lockd has to maintain its own state as to who has what locks. If this isn't a user/kernel ABI/API problem, it should be easily solvable, and we should do that following 5.1-RELEASE. > I believe there were also some issues with atomicity in POSIX partial > file locking on FreeBSD that have since been fixed. > > Consequently, I punted when I wrote the rpc.lockd code to support POSIX > partial file locking. The server rpc.lockd locks the *entire file* when > it gets an NFS request to lock any portion of it. In addition, it will > return an immediate fail if the kernel has any portion of the desired > file locked. This sounds like a reasonable work-around given that the common case is currently whole-file locking; we just need to make sure that the semantics are exposed properly to the application. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Network Associates Laboratories