Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751646AbZIYQxZ (ORCPT ); Fri, 25 Sep 2009 12:53:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751453AbZIYQxZ (ORCPT ); Fri, 25 Sep 2009 12:53:25 -0400 Received: from sca-es-mail-2.Sun.COM ([192.18.43.133]:58946 "EHLO sca-es-mail-2.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750972AbZIYQxY (ORCPT ); Fri, 25 Sep 2009 12:53:24 -0400 MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-disposition: inline Content-type: text/plain; CHARSET=US-ASCII Date: Fri, 25 Sep 2009 10:53:16 -0600 From: Andreas Dilger Subject: Re: [PATCH] vfs: new O_NODE open flag In-reply-to: <20090925123747.GA31228@gallifrey> To: "Dr. David Alan Gilbert" Cc: Miklos Szeredi , Andreas Gruenbacher , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Message-id: <20090925165316.GT10562@webber.adilger.int> X-GPG-Key: 1024D/0D35BED6 X-GPG-Fingerprint: 7A37 5D79 BF1B CECA D44F 8A29 A488 39F5 0D35 BED6 References: <200909250223.58664.agruen@suse.de> <20090925123747.GA31228@gallifrey> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1485 Lines: 39 On Sep 25, 2009 13:37 +0100, Dr. David Alan Gilbert wrote: > * Miklos Szeredi (miklos@szeredi.hu) wrote: > > On Fri, 25 Sep 2009, Andreas Gruenbacher wrote: > > > On Thursday, 24 September 2009 16:51:58 Miklos Szeredi wrote: > > > > This patch adds a new open flag, O_NODE. This flag means: open just > > > > the filesystem node instead of the object referenced by the node. > > > > > > What is the intended use for O_NODE? > > > > It lets userspace file descriptors reference a inode without actually > > "dereferencing" it to get the underlying object. This allows for a > > couple of new things: > > > > - opening a special file (device/socket/fifo) without side effects > > > > - opening a symlink > > > > - opening any type of file without any permission is also possible > > (of course the resuling file descriptor may not be read or written) > > > > The above allows fstat(), fchmod(), ioctl(), etc to be used for files > > previously not possible. > > Given an fd opened in this way is it possible to reopen it normally and > be guarenteed to get the same object? That was something I'd be interested in as well. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. -- 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/