From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Waychison Subject: Re: [RFC][PATCH 1/8] namespace: use global namespace semaphore Date: Fri, 03 Jun 2005 10:24:08 -0700 Message-ID: <42A09238.7080204@waychison.com> References: <429BD8B7.7070906@waychison.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Miklos Szeredi , linux-fsdevel , jamie@shareable.org, Al Viro Return-path: Received: from 216-239-45-4.google.com ([216.239.45.4]:8831 "EHLO 216-239-45-4.google.com") by vger.kernel.org with ESMTP id S261409AbVFCRZB (ORCPT ); Fri, 3 Jun 2005 13:25:01 -0400 To: Ian Kent In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org 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). Mike Waychison