From mboxrd@z Thu Jan 1 00:00:00 1970 From: raven@themaw.net Subject: Re: [RFC][PATCH 1/8] namespace: use global namespace semaphore Date: Sat, 4 Jun 2005 12:38:07 +0800 (WST) Message-ID: References: <429BD8B7.7070906@waychison.com> <42A09238.7080204@waychison.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Miklos Szeredi , linux-fsdevel , jamie@shareable.org, Al Viro Return-path: Received: from wombat.indigo.net.au ([202.0.185.19]:42255 "EHLO wombat.indigo.net.au") by vger.kernel.org with ESMTP id S261235AbVFDEsH (ORCPT ); Sat, 4 Jun 2005 00:48:07 -0400 To: Mike Waychison In-Reply-To: <42A09238.7080204@waychison.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Fri, 3 Jun 2005, Mike Waychison wrote: > Ian Kent wrote: > > On Tue, 31 May 2005, Miklos Szeredi wrote: > > > > > > > >There's not really anything magic about using the follow link method. > > > >It's just a bit of a cheat as a directory can't also be a symlink and the > > > >callback comes at exactly the right time to make stuff happen. > > > > > >So is it something like this? > > > > > > - autofs is mounted over direct mountpoint 'dm' > > > > > > - when dm is looked up, autofs's follow_link method is called > > > > > > - this triggers the actual mount in the daemon, which mounts over > > > the autofs filesystem (with some trick to avoid recursion) > > > > > > Admit, I haven't paid enough attention to recursion. > > Ouch! Caught by that the other day. > > > > > > > - when the daemon is finished, the autofs's follow_link method > > > enters the new mount (how?) and returns > > > > > > A function functionally similar to follow_mount of namei.c. Which needs the > > appropriate vfsmount. > > > > > > > > > >Why do you need the mount topology for this? > > > > > > Don't. Actually need the nameidata upto date when the follow_link method is > > called. > > > > However you can't rely on this for expiry checks, as the vfsmount can change > (--rbind, CLONE_NEWNS). No. This is a limitation of the old autofs design and will probably remain so for the forseable future. It's one of the issues that I hope autofsng will address. I can deal with expirey otherwise. Ian