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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 D401EC433DF for ; Thu, 27 Aug 2020 07:37:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AE7220738 for ; Thu, 27 Aug 2020 07:37:07 +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="mI9Iyg9a" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728289AbgH0HhH (ORCPT ); Thu, 27 Aug 2020 03:37:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726851AbgH0HhE (ORCPT ); Thu, 27 Aug 2020 03:37:04 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B89FBC061264; Thu, 27 Aug 2020 00:37:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=Xv7uMIBubFsUa3JJj4NSseTuK/54PDkvPcIbF9EYCl4=; b=mI9Iyg9arOdrPB/JE4kqaKMJfh IXF/on35MpgAQBCEU4wRCtakJxsqGRwU6n0CUOVRxRKr6iuqNU0rWdxpH3jQZLNoka3l2egEYjZy0 LtsUtVghArYTMw+g+VB9kEF/TfLCFaHe3IPixE6dlFSs43zYp4j2GyI6AIsMt7JloYz1MfNUzzTB+ 1gQCKVviobJDnesIN93iIzBlv6ctolYUulvMo7o1XSHVT3ANe2i30zTumTxd56zOcoBWHKqUBkhGb INmQHB3ailO5wGdaNYAEui90G1uSJJbfTFsXOp1l/Hzt6WuMzL03z+aQ9agf4tIgQP4y1oyJ8C7Pc 9Mlqw3ww==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kBCSy-000888-VJ; Thu, 27 Aug 2020 07:37:01 +0000 Date: Thu, 27 Aug 2020 08:37:00 +0100 From: Christoph Hellwig To: Amir Goldstein Cc: Christoph Hellwig , Brian Foster , fstests , linux-xfs , Josef Bacik Subject: Re: [PATCH 1/4] generic: require discard zero behavior for dmlogwrites on XFS Message-ID: <20200827073700.GA30374@infradead.org> References: <20200826143815.360002-1-bfoster@redhat.com> <20200826143815.360002-2-bfoster@redhat.com> <20200827070237.GA22194@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: fstests-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: fstests@vger.kernel.org On Thu, Aug 27, 2020 at 10:29:05AM +0300, Amir Goldstein wrote: > I figured you'd say something like that :) > but since we are talking about dm-thin as a solution for predictable > behavior at the moment and this sanity check helps avoiding adding > new tests that can fail to some extent, is the proposed bandaid good enough > to keep those tests alive until a better solution is proposed? Well, the problem is that a test that wants to reliable nuke data needs to... *drumroll* reliably nuke data. Which means zeroing or at least a known pattern. discard doesn't give you that. I don't see how a plain discard is going to work for any file system for that particular case.