From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD19FC0650F for ; Sun, 11 Aug 2019 16:15:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 98B3B2087B for ; Sun, 11 Aug 2019 16:15:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726492AbfHKQPk (ORCPT ); Sun, 11 Aug 2019 12:15:40 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:49113 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726458AbfHKQPk (ORCPT ); Sun, 11 Aug 2019 12:15:40 -0400 Received: from callcc.thunk.org (75-104-84-221.mobility.exede.net [75.104.84.221] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x7BGFE9T007584 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 11 Aug 2019 12:15:25 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 9B2644218EF; Sun, 11 Aug 2019 12:15:08 -0400 (EDT) Date: Sun, 11 Aug 2019 12:15:08 -0400 From: "Theodore Y. Ts'o" To: Christoph Hellwig Cc: Ext4 Developers List , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org Subject: Re: [PATCH 1/3] ext4: return the extent cache information via fiemap Message-ID: <20190811161508.GA5878@mit.edu> References: <20190809181831.10618-1-tytso@mit.edu> <20190810073343.GA12777@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190810073343.GA12777@infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sat, Aug 10, 2019 at 12:33:43AM -0700, Christoph Hellwig wrote: > > On Fri, Aug 09, 2019 at 02:18:29PM -0400, Theodore Ts'o wrote: > > For debugging reasons, it's useful to know the contents of the extent > > cache. Since the extent cache contains much of what is in the fiemap > > ioctl, extend the fiemap interface to return this information via some > > ext4-specific flags. > > Nak. No weird fs specific fiemap flags that aren't even in the uapi > header. Please provide your own debug only interface. I can understand why you don't like this from the principle of the thing. I'll create my own ioctl, and make a copy of ioctl_fiemap() into ext4 and modify it for my needs. I was trying to avoid needing to do that, since there is plenty of space in the fiemap flags to carve out space for file-specific specific flags, and avoiding making extra copies of code for the purposes of reuse weighed more heavily than "no fs-specific fiemap flags". - Ted