From owner-freebsd-current@FreeBSD.ORG  Wed Jan 14 12:38:33 2004
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
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 08FFD16A4CE; Wed, 14 Jan 2004 12:38:33 -0800 (PST)
Received: from gw.catspoiler.org (217-ip-163.nccn.net [209.79.217.163])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 70D4B43D6E; Wed, 14 Jan 2004 12:38:21 -0800 (PST)
	(envelope-from truckman@FreeBSD.org)
Received: from FreeBSD.org (mousie.catspoiler.org [192.168.101.2])
	by gw.catspoiler.org (8.12.9p2/8.12.9) with ESMTP id i0EKcD7E040320;
	Wed, 14 Jan 2004 12:38:17 -0800 (PST)
	(envelope-from truckman@FreeBSD.org)
Message-Id: <200401142038.i0EKcD7E040320@gw.catspoiler.org>
Date: Wed, 14 Jan 2004 12:38:13 -0800 (PST)
From: Don Lewis <truckman@FreeBSD.org>
To: tjr@FreeBSD.org
In-Reply-To: <20040114140818.GA15471@cat.robbins.dropbear.id.au>
MIME-Version: 1.0
Content-Type: TEXT/plain; charset=us-ascii
cc: current@FreeBSD.org
Subject: Re: simplifying linux_emul_convpath()
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 14 Jan 2004 20:38:33 -0000

On 15 Jan, Tim Robbins wrote:
> On Wed, Jan 14, 2004 at 05:08:51AM -0800, Don Lewis wrote:
> 
>> I just stumbled across a vnode locking violation in
>> linux_emul_convpath().  Rather than locking and unlocking each vnode for
>> the VOP_GETATTR() calls, is there any reason that this code should not
>> be simplified to just compare the vnode pointers rather than fetching
>> the vnode attributes and comparing the attributes for equality.
> 
> I'm having trouble convincing myself that comparing vnode pointers
> would work with stackable filesystems. Then again, null_getattr()
> changes va_fsid, so linux_emul_convpath() may not handle stacking
> properly right now anyway.

They won't compare equal in either case, but I think that is what you
want in this case anyway.  I don't think we want a Linux application
opening a file to trigger the match code if it does a lookup on
/some/other/path if that location is a nullfs mounted version of of
/compat/linux.