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_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 EE79FC55199 for ; Sun, 26 Apr 2020 10:03:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C8EC62071C for ; Sun, 26 Apr 2020 10:03:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="X23VxZM5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726141AbgDZKD5 (ORCPT ); Sun, 26 Apr 2020 06:03:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726118AbgDZKDz (ORCPT ); Sun, 26 Apr 2020 06:03:55 -0400 Received: from mail-lj1-x242.google.com (mail-lj1-x242.google.com [IPv6:2a00:1450:4864:20::242]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C424C061A0C for ; Sun, 26 Apr 2020 03:03:55 -0700 (PDT) Received: by mail-lj1-x242.google.com with SMTP id l19so14398819lje.10 for ; Sun, 26 Apr 2020 03:03:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=1Qn7dMUaScW6RStYYl/ei8skK7kxyIxqczbatJhHU64=; b=X23VxZM5wrV7BnKT3+qwneSrIo7JK+pSWMaHd0vBdM42rmCs8qDhUdUH6g7ur2mta3 LAn+xoD9fQM4HBi24MIE+begRcSHkqP49nKmIBeP1ipMq/u1iz91WwjKCtP9RJMnVJ91 rt3GiacKXNSf7JHZF/6R7wLn+tPIaK+HHIA32Bz3oUVKDf53RTMU5ylzEQdnUEmFCqLb A/uoB4Hokt1H8bh3RkbtpiM6QfHKmkH5il2WG4nWpdgnRtb93UkdoF5sib63UB7D8FZT GSSvXcL7AXJfPtlKCltva0/H2r7r8kO289KUMA0JJ8aAN/l9vh9zwaqwkqnAk4Qihuok cigw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=1Qn7dMUaScW6RStYYl/ei8skK7kxyIxqczbatJhHU64=; b=egPH0GuIwVmT7bAgnNPv00cdP98u583H4/rbANmsZuvFOTTBFLFVh0qmbrnApWtvMf U0PipUqKkVmVZkfCvHL7Vkg8CjTe0mzD7+3o5gwANVGu4TknLdOpYSB9kvy/KGDVwuGl ZmJgwpGN0/N2stMflyHzkExddvnhPnBtXqQGUZPgpbFfQx6mcqyUQ0mtXLY08XSaDynX Cz0DCzdG5TXhEVUY6vcZcSMRgSoqJYdDfqyYTKXmzOsPcgJ/E/YHbJHTHT16EQSGgFKs 7OvB3U6qM6yMzTgfjLJu4Rm0bSnkSCgGOD3yhWv1RDQ273j0aitdGfUwiLd31Se16PTH W7Xg== X-Gm-Message-State: AGi0PubwCscaBmxqRcdhryK31CEKLBJbJJTmhlP9L5Uh79WKOSxvmiCe nTtN13RimSrEprJ3nvAFGPJ+nlum X-Google-Smtp-Source: APiQypLmQDxoTbL7GqCk7nRP7bzC5souxykhHdfAATZ9Haj/4rMNqzrjGHeIhcCuapN5cxadKVj/3w== X-Received: by 2002:a2e:9996:: with SMTP id w22mr7899400lji.59.1587895433121; Sun, 26 Apr 2020 03:03:53 -0700 (PDT) Received: from ?IPv6:2a00:1370:812d:48ee:3630:6817:757e:9dcf? ([2a00:1370:812d:48ee:3630:6817:757e:9dcf]) by smtp.gmail.com with ESMTPSA id g22sm6642099ljl.17.2020.04.26.03.03.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 26 Apr 2020 03:03:52 -0700 (PDT) Subject: Re: Help needed to recover from partition resize/move To: Chris Murphy , Yegor Yegorov Cc: Btrfs BTRFS References: From: Andrei Borzenkov Message-ID: <4c46f2a2-8603-977f-74ec-449d3cfb1fb8@gmail.com> Date: Sun, 26 Apr 2020 13:03:51 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org 26.04.2020 10:36, Chris Murphy пишет: >> superblock: bytenr=274877906944, device=/dev/nvme0n1p3 >> --------------------------------------------------------- >> ERROR: bad magic on superblock on /dev/nvme0n1p3 at 274877906944 > > ? OK but why does it even go looking for this 3rd super? A file system > of this size doesn't have a 3rd super, which appears at 256G. > > There's no dmesg for the resize? This should report the block group > changes that happen as part of the resize; and also the fs size > change; and also the partition map change. And if it is rebooted, then > dump-super shouldn't be looking for a 3rd super. > Most likely it is code bug. The condition is if (ret == 0 && errno == 0) but errno is not guaranteed to be reset to zero after previous errors. Linux errno(3): The value in errno is significant only when the return value of the call indicated an error (i.e., -1 from most system calls; -1 or NULL from most library functions); a function that succeeds is allowed to change errno. The value of errno is never set to zero by any system call or library function. And pread64(2) Note that is not an error for a successful call to transfer fewer bytes than requested (see read(2) and write(2)). On error, -1 is returned and errno is set to indicate the cause of the error. So errno check here is entirely redundant, the only case when pread64 returns 0 is reading past EOF.