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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 63ED0C31E40 for ; Mon, 12 Aug 2019 06:47:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25B11214C6 for ; Mon, 12 Aug 2019 06:47:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="T4Eb5Aiw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726334AbfHLGr3 (ORCPT ); Mon, 12 Aug 2019 02:47:29 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:39150 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725887AbfHLGr2 (ORCPT ); Mon, 12 Aug 2019 02:47:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=BePnk0X3rfDaLaLKHzFIKVX/0zCxcshoDltXUneFxlg=; b=T4Eb5AiwGxnuc5XE45CQgSeib Ya+w45XZJHhy3Z0YExqsYjDp0kA7BCXPbTRD9jgn5OPX+KQkjukldzQJpH3M2ZuRONcG+MsORLYQD /Lx3G2/vCLZhwqvyZ7oZAdaaJlsL395/Yv5dUN2+yZ4V09bREYMPfpJwCzlueyxdhxMbdvzLumWBU bLqjt0ZZAFv81n7jfGcn7tTTfgxI/P+GzrGK2W/y4lVz3vZyhM3zYonLY8ARtuWZ8qqpgp+1puoB1 nLHQUjfxgySWXaWG7NsXvjvVlQ+iC+uGvvrWqjJzLle1cm3VI8tJ7isdwphd8yv67Qv/adfelqpMZ gmM0mK+ww==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hx476-0005pt-1P; Mon, 12 Aug 2019 06:47:28 +0000 Date: Sun, 11 Aug 2019 23:47:28 -0700 From: Christoph Hellwig To: "Theodore Y. Ts'o" Cc: Christoph Hellwig , 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: <20190812064728.GA22302@infradead.org> References: <20190809181831.10618-1-tytso@mit.edu> <20190810073343.GA12777@infradead.org> <20190811161508.GA5878@mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190811161508.GA5878@mit.edu> User-Agent: Mutt/1.11.4 (2019-03-13) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sun, Aug 11, 2019 at 12:15:08PM -0400, Theodore Y. Ts'o wrote: > > 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 think mixing up in-kernel temporary state with the on-disk layout is a bad idea, yes. I think it is an even worse idea to try to sneak it in without API review in an undocumented fashion. > > 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". I think dumping your internal state is a candidate for debugs, not a copy of ioctl_fiemap.