Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752406AbZIYLhu (ORCPT ); Fri, 25 Sep 2009 07:37:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751611AbZIYLhs (ORCPT ); Fri, 25 Sep 2009 07:37:48 -0400 Received: from mx.treblig.org ([80.68.94.177]:37406 "EHLO mx.treblig.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751259AbZIYLhr (ORCPT ); Fri, 25 Sep 2009 07:37:47 -0400 Date: Fri, 25 Sep 2009 13:37:47 +0100 From: "Dr. David Alan Gilbert" To: Miklos Szeredi Cc: Andreas Gruenbacher , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] vfs: new O_NODE open flag Message-ID: <20090925123747.GA31228@gallifrey> References: <200909250223.58664.agruen@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Chocolate: 70 percent or better cocoa solids preferably X-Operating-System: Linux/2.6.29.2-bytemark-kvm-tickless-2009-05-05 (i686) X-Uptime: 13:35:56 up 122 days, 5:57, 1 user, load average: 0.00, 0.00, 0.00 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1521 Lines: 36 * 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? Dave -- -----Open up your eyes, open up your mind, open up your code ------- / Dr. David Alan Gilbert | Running GNU/Linux on Alpha,68K| Happy \ \ gro.gilbert @ treblig.org | MIPS,x86,ARM,SPARC,PPC & HPPA | In Hex / \ _________________________|_____ http://www.treblig.org |_______/ -- 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/