Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265596AbUALQ7S (ORCPT ); Mon, 12 Jan 2004 11:59:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266212AbUALQ7S (ORCPT ); Mon, 12 Jan 2004 11:59:18 -0500 Received: from nwkea-mail-1.sun.com ([192.18.42.13]:43140 "EHLO nwkea-mail-1.sun.com") by vger.kernel.org with ESMTP id S265596AbUALQ7H (ORCPT ); Mon, 12 Jan 2004 11:59:07 -0500 Date: Mon, 12 Jan 2004 11:58:48 -0500 From: Mike Waychison Subject: Re: [autofs] [RFC] Towards a Modern Autofs In-reply-to: To: raven@themaw.net Cc: Jim Carter , autofs mailing list , Kernel Mailing List Message-id: <4002D248.2070304@sun.com> MIME-version: 1.0 Content-type: multipart/signed; boundary=------------enig8E1C5834750FE2B509569C84; protocol="application/pgp-signature"; micalg=pgp-sha1 X-Accept-Language: en User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.5) Gecko/20031107 Debian/1.5-3 X-Enigmail-Version: 0.82.2.0 X-Enigmail-Supports: pgp-inline, pgp-mime References: <40029C19.409@sun.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3505 Lines: 109 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig8E1C5834750FE2B509569C84 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit raven@themaw.net wrote: >On Tue, 13 Jan 2004 raven@themaw.net wrote: > > > >>On Mon, 12 Jan 2004, Mike Waychison wrote: >> >> >> >>>>Transparency of an autofs filesystem (as I'm calling it) is the situation >>>>where, given a map >>>> >>>>/usr /man1 server:/usr/man1 >>>> /man2 server:/usr/man2 >>>> >>>>where the filesystem /usr contains, say a directory lib, that needs to be >>>>available while also seeing the automounted directories. >>>> >>>> >>>> >>>> >>>> >>>I see. This requires direct mount triggers to do properly. Trying to >>>do it with some sort of passthrough to the underlying filesystem is a >>>nightmare waiting to happen.. >>> >>> >>> >>So what are we saying here? >> >>We install triggers at /usr/man1 and /usr/man2. >>Then suppose the map had a nobrowse option. >>Does the trigger also take care of hiding man1 and man2? >> >>Is there some definition of these triggers? >> >> >> > >And I have another question concerning namespaces. > >Given that there may be several namespaces, each of which may or may not >have a trigger on this dentry, is there some sort of list of triggers? > >How do the triggers know who owns them? > > > > This is the reason I went with using distinct filesystems to perform the triggers. If we use follow_link logic, we will have a reference to the respective vfsmount. Dentry's themselves know nothing about the triggers, as the triggers just look like a mounted filesystem. The vfsmount information has enough information for autofs to call a userspace agent through hotplug and have userspace handle the mount. In effect, there is no daemon so nobody 'owns' a trigger in the same sense as with autofs3/4. As far as userspace is concerned, an autofs filesystem is mounted as is any other filesystem. All that is required is a proper set of mount options. For example, mounting auto_home on /home is: mount -t autofs -o maptype=indirect,mapname=auto_home auto_home /home Whenever somebody traverses into a subdir in /home within any namespace this autofs filesystem has been inherited, userspace is invoked (in that namespace) to perform the mount. Again, there is no 'ownership' other than maybe calling the namespace it resides it the 'owner', as you would for any other mountpoint. -- Mike Waychison Sun Microsystems, Inc. 1 (650) 352-5299 voice 1 (416) 202-8336 voice mailto: Michael.Waychison@Sun.COM http://www.sun.com ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NOTICE: The opinions expressed in this email are held by me, and may not represent the views of Sun Microsystems, Inc. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --------------enig8E1C5834750FE2B509569C84 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (GNU/Linux) Comment: Using GnuPG with Debian - http://enigmail.mozdev.org iD8DBQFAAtJIdQs4kOxk3/MRAroLAKCK3K6/m+s+4z6i9/lmUi0C8FDDuACffvD7 Urm2y6k9IR6ct5RZ8FLFKno= =BwsR -----END PGP SIGNATURE----- --------------enig8E1C5834750FE2B509569C84-- - 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/