From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Dilger Subject: Re: [PATCH] add a FMODE flag to make XFS invisible I/O less hacky Date: Fri, 28 Nov 2008 15:58:42 -0700 Message-ID: <20081128225659.GU3186@webber.adilger.int> References: <20081128112402.GA32740@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7BIT Cc: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org To: Christoph Hellwig Return-path: Received: from sca-es-mail-1.Sun.COM ([192.18.43.132]:47481 "EHLO sca-es-mail-1.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752815AbYK1W7D (ORCPT ); Fri, 28 Nov 2008 17:59:03 -0500 Received: from fe-sfbay-09.sun.com ([192.18.43.129]) by sca-es-mail-1.sun.com (8.13.7+Sun/8.12.9) with ESMTP id mASMwrVf016622 for ; Fri, 28 Nov 2008 14:58:54 -0800 (PST) Received: from conversion-daemon.fe-sfbay-09.sun.com by fe-sfbay-09.sun.com (Sun Java System Messaging Server 6.2-8.04 (built Feb 28 2007)) id <0KB200501FPQ6000@fe-sfbay-09.sun.com> (original mail from adilger@sun.com) for linux-fsdevel@vger.kernel.org; Fri, 28 Nov 2008 14:58:53 -0800 (PST) In-reply-to: <20081128112402.GA32740@lst.de> Content-disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Nov 28, 2008 12:24 +0100, Christoph Hellwig wrote: > XFS has a mode called invisble I/O that doesn't update any of the > timestamps. It's used for HSM-style applications and exposed through > the nasty open by handle ioctl. > > Instead of doing directly assignment of file operations that set an > internal flag for it add a new FMODE_INVISIBLE flag that we can check > in the normal file operations. Why not call this "FMODE_NOCMTIME" similar to the inode flag "S_NOCMTIME" that already exists, and . That makes it more clear what is being done, instead of calling it "INVISIBLE". It should also not be possible to skip ctime updates for non-root users, as that provides some forensic trail if files have been modified by users. Not sure if that is relevant here though (it looks like this is only used internally), but worth mentioning in any case. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.