Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751092AbWAYSDY (ORCPT ); Wed, 25 Jan 2006 13:03:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751101AbWAYSDY (ORCPT ); Wed, 25 Jan 2006 13:03:24 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:51880 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1751092AbWAYSDX (ORCPT ); Wed, 25 Jan 2006 13:03:23 -0500 To: Trond Myklebust Cc: Arjan van de Ven , Alan Cox , Hubertus Franke , Dave Hansen , Greg KH , "Serge E. Hallyn" , linux-kernel@vger.kernel.org, Cedric Le Goater Subject: Re: RFC [patch 13/34] PID Virtualization Define new task_pid api References: <20060117143258.150807000@sergelap> <20060117143326.283450000@sergelap> <1137511972.3005.33.camel@laptopd505.fenrus.org> <20060117155600.GF20632@sergelap.austin.ibm.com> <1137513818.14135.23.camel@localhost.localdomain> <1137518714.5526.8.camel@localhost.localdomain> <20060118045518.GB7292@kroah.com> <1137601395.7850.9.camel@localhost.localdomain> <43D14578.6060801@watson.ibm.com> <43D52592.8080709@watson.ibm.com> <1138050684.24808.29.camel@localhost.localdomain> <1138062125.24808.47.camel@localhost.localdomain> <1138137060.14675.73.camel@localhost.localdomain> <1138137305.2977.92.camel@laptopd505.fenrus.org> <1138201811.8720.9.camel@lade.trondhjem.org> From: ebiederm@xmission.com (Eric W. Biederman) Date: Wed, 25 Jan 2006 11:01:34 -0700 In-Reply-To: <1138201811.8720.9.camel@lade.trondhjem.org> (Trond Myklebust's message of "Wed, 25 Jan 2006 10:10:11 -0500") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1485 Lines: 39 Trond Myklebust writes: > On Wed, 2006-01-25 at 02:58 -0700, Eric W. Biederman wrote: >> >> On Maw, 2006-01-24 at 12:26 -0700, Eric W. Biederman wrote: >> >> > There is at least NFS lockd that appreciates having a single integer >> >> > per process unique identifier. So there is a practical basis for >> >> > wanting such a thing. > > The NFS lock manager mainly wants a unique 32-bit identifier that can > follow clone(CLONE_FILES). The reason is that the Linux VFS is forced to > use the pointer to the file table as the "process identifier" for posix > locks (i.e. fcntl() locks). Ok. I think I was thinking of a different case, but if I missed one this could explain the weirdness I was seeing. Let me list the cases I know of and see if I hit what you are thinking of. fs/nfs/nfs3proc.c:nfs3_proc_create() For O_EXCL we have arg.verifier = current->pid. fs/lockd/clntproc.c:nlmclnt_setlockargs() We have: lock->oh.len = sprintf(req->a_owner, "%d@%s", current->pid, system_utsname.nodename); I think this is the fcntl() case. I would suggest fl_pid might have something to do with it but that is part flock based locking. So I'm not certain I see the part of NFS you are refering to. Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/