From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Dilger Subject: Re: [PATCH 0/4] Fiemap, an extent mapping ioctl - round 2 Date: Fri, 04 Jul 2008 02:31:14 -0600 Message-ID: <20080704083114.GN6239@webber.adilger.int> References: <20080625221835.GQ28100@wotan.suse.de> <1214489061.6237.16.camel@norville.austin.ibm.com> <4863A483.5060303@redhat.com> <1214490465.6237.24.camel@norville.austin.ibm.com> <486C13B7.4030402@hp.com> <20080703111726.GZ29319@disturbed> <486CC1FA.10003@hp.com> <20080703225124.GB29319@disturbed> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7BIT To: jim owens , linux-fsdevel@vger.kernel.org Return-path: Received: from sca-es-mail-1.Sun.COM ([192.18.43.132]:38996 "EHLO sca-es-mail-1.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753301AbYGDIbR (ORCPT ); Fri, 4 Jul 2008 04:31:17 -0400 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 m648VGkl002001 for ; Fri, 4 Jul 2008 01:31:16 -0700 (PDT) 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 <0K3H00K013LU0N00@fe-sfbay-09.sun.com> (original mail from adilger@sun.com) for linux-fsdevel@vger.kernel.org; Fri, 04 Jul 2008 01:31:15 -0700 (PDT) In-reply-to: <20080703225124.GB29319@disturbed> Content-disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Jul 04, 2008 08:51 +1000, Dave Chinner wrote: > The fact that it's only implemented in XFS right now has absolutely > *zero* consideration in determining this feature is necessary or > not. The fact that the only existing extent mapping interface in > Linux already defines it this way and it is in use by existing > userspace utilities that *expect this semantic* is much, much more > important. > > FWIW, if ext4 had this atomic sync+map (which it could do), would > you still be complaining about it? Actually, the ext4 ->fiemap() method DOES grab a lock that will prevent the file layout changing during the mapping, assuming the extent array is large enough. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.