From owner-freebsd-fs@FreeBSD.ORG Fri Feb 16 13:25:50 2007 Return-Path: X-Original-To: fs@freebsd.org Delivered-To: freebsd-fs@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 2110216A401; Fri, 16 Feb 2007 13:25:50 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [209.31.154.42]) by mx1.freebsd.org (Postfix) with ESMTP id E2C7413C494; Fri, 16 Feb 2007 13:25:49 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from fledge.watson.org (fledge.watson.org [209.31.154.41]) by cyrus.watson.org (Postfix) with ESMTP id 40A1D46CCA; Fri, 16 Feb 2007 07:54:39 -0500 (EST) Date: Fri, 16 Feb 2007 12:54:39 +0000 (GMT) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: Kostik Belousov In-Reply-To: <20070215153135.GI39168@deviant.kiev.zoral.com.ua> Message-ID: <20070216125007.D38234@fledge.watson.org> References: <20070204023711.GA3393@genius.tao.org.uk> <20070215135750.GR64768@obiwan.tataz.chchile.org> <20070215152259.GA2950@genius.tao.org.uk> <20070215153135.GI39168@deviant.kiev.zoral.com.ua> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Josef Karthauser , hackers@freebsd.org, Jeremie Le Hen , fs@freebsd.org Subject: Re: nullfs and named pipes. X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Feb 2007 13:25:50 -0000 On Thu, 15 Feb 2007, Kostik Belousov wrote: > On Thu, Feb 15, 2007 at 03:22:59PM +0000, Josef Karthauser wrote: >> On Thu, Feb 15, 2007 at 02:57:50PM +0100, Jeremie Le Hen wrote: >>> >>> Note that all processes within a jail can only intefere with processes >>> from another jail or host as if they were on different machines. This >>> means they can communicate through PF_INET for instance but not PF_LOCAL. >> >> You might think so! However that's not what's going on here. >> >> The named pipe/nullfs issue is nothing to do with jails. It's just that >> nullfs is broken with respect to named pipes as I've previously reported. >> However with this patch: >> >> cvs diff: Diffing . >> Index: null_subr.c >> =================================================================== >> RCS file: /home/ncvs/src/sys/fs/nullfs/null_subr.c,v >> retrieving revision 1.48.2.1 >> diff -u -r1.48.2.1 null_subr.c >> --- null_subr.c 13 Mar 2006 03:05:17 -0000 1.48.2.1 >> +++ null_subr.c 14 Feb 2007 00:02:28 -0000 >> @@ -235,6 +235,8 @@ >> xp->null_vnode = vp; >> xp->null_lowervp = lowervp; >> vp->v_type = lowervp->v_type; >> + if (vp->v_type == VSOCK || vp->v_type == VFIFO) >> + vp->v_un = lowervp->v_un; > > I'm wondering is some reference counting needed there ? Yes, I find this a bit worrying also, but I don't know enough about how nullfs works to reason about it. What happens when a vnode in the bottom layer has its on-disk reference count drop to zero -- is the vnode in the top layer invalidated somehow? Robert N M Watson Computer Laboratory University of Cambridge