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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 DE906C43381 for ; Mon, 4 Mar 2019 15:46:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B7B03206B8 for ; Mon, 4 Mar 2019 15:46:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727195AbfCDPqG (ORCPT ); Mon, 4 Mar 2019 10:46:06 -0500 Received: from mailgw-01.dd24.net ([193.46.215.41]:37685 "EHLO mailgw-01.dd24.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726076AbfCDPqG (ORCPT ); Mon, 4 Mar 2019 10:46:06 -0500 Received: from mailpolicy-01.live.igb.homer.key-systems.net (mailpolicy-02.live.igb.homer.key-systems.net [192.168.1.27]) by mailgw-01.dd24.net (Postfix) with ESMTP id 72E415FFAA; Mon, 4 Mar 2019 15:46:04 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mailpolicy-02.live.igb.homer.key-systems.net Received: from smtp.dd24.net ([192.168.1.35]) by mailpolicy-01.live.igb.homer.key-systems.net (mailpolicy-02.live.igb.homer.key-systems.net [192.168.1.25]) (amavisd-new, port 10235) with ESMTP id vvE5YDn04ete; Mon, 4 Mar 2019 15:46:02 +0000 (UTC) Received: from heisenberg.fritz.box (ppp-82-135-82-31.dynamic.mnet-online.de [82.135.82.31]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.dd24.net (Postfix) with ESMTPSA; Mon, 4 Mar 2019 15:46:02 +0000 (UTC) Message-ID: <35900bed4a0ecb25b25c8d35be8bd1a5c38b59a8.camel@scientia.net> Subject: Re: Reproducer for "compressed data + hole data corruption bug, 2018 edition" still works on 4.20.7 From: Christoph Anton Mitterer To: fdmanana@gmail.com Cc: linux-btrfs Date: Mon, 04 Mar 2019 16:46:00 +0100 In-Reply-To: References: <20180823031125.GE13528@hungrycats.org> <20190212030838.GB9995@hungrycats.org> <20190212165916.GA23918@hungrycats.org> <20190212181328.GB23918@hungrycats.org> <95e4d9825c2565473184765c4d77ae0015d01580.camel@scientia.net> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5-1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Fri, 2019-02-15 at 12:02 +0000, Filipe Manana wrote: > Upgrade to a kernel with the patch (none yet) or build it from > source? > Not sure what kind of advice you are looking for. Well more something of the kind that Zygo wrote in his mail, i.e some explanation of the whole issue in order to find out whether one might be affected or not. > As I said in the previous reply, and in the patch's changelog [1], > the > corruption happens at read time. > That means nothing stored on disk is corrupted. It's not the end of > the world. Well but there are many cases where data is read and then written again... and while Zygo's mail already answers a lot, at least the question of whether it could happen on btrfs send/receive is still open. My understanding was that btrfs is considered "stable" for the normal use cases (so e.g. perhaps without special features like raid56). Data corruption is always quite serious, even if it's just on reads and people may have workloads where data is read (possibly with corruption) and (permanently) written again... so the whole thing *could* be quite serious and IMO justifies a more thorough explanation for end-users and not just a small commit message for developers. Also, while it was really great to see how fast this got fixed then in the end... it's also a bit worrying that Zygo apparently reported it already some time ago and it got somehow lost. Cheers, Chris.