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=-2.0 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 C6114C32771 for ; Thu, 9 Jan 2020 10:19:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 759DF2072A for ; Thu, 9 Jan 2020 10:19:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728944AbgAIKT2 (ORCPT ); Thu, 9 Jan 2020 05:19:28 -0500 Received: from zaphod.cobb.me.uk ([213.138.97.131]:60310 "EHLO zaphod.cobb.me.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728767AbgAIKT2 (ORCPT ); Thu, 9 Jan 2020 05:19:28 -0500 Received: by zaphod.cobb.me.uk (Postfix, from userid 107) id 438F59C363; Thu, 9 Jan 2020 10:19:26 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cobb.uk.net; s=201703; t=1578565166; bh=wiO0tLFoL7RVEHEeTYZWwdopwQ4YKm8lft4DEXAgZdM=; h=Subject:To:References:From:Date:In-Reply-To:From; b=rIAUWG6/kxQeolGpP679DYyj2eA/EouCJayO/uFyGwpQEYRmA/Z2dVA4+KxLy+2Yh q5DdBvQqL9ZeGKqVHIlvsPzIGyPljE3cWhOKytDMUyUrTuWx5Q43mFstp3Yy0pXGih ar+3oNEqWHmhA7guzsChfNv4yqsJb8lPGlkb2rpfofQIC1ad8ng2ojAm6EcIMHUlwt v11gPXRjBXOuCBdLNW0RtrgEodSSdX89PuwlPwvcPHNJ+LQoeBvA8eIbDDClV7b0q9 p0m3KXdLFORluwKAWQuAWqcLIUwXG1lCubcQiJYWgl7SQErmpkDKo+9K/lMqq6CF+V st89hc7W9Pz+g== Received: from black.home.cobb.me.uk (unknown [192.168.0.205]) by zaphod.cobb.me.uk (Postfix) with ESMTP id 917C69BD54; Thu, 9 Jan 2020 10:19:25 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cobb.uk.net; s=201703; t=1578565165; bh=wiO0tLFoL7RVEHEeTYZWwdopwQ4YKm8lft4DEXAgZdM=; h=Subject:To:References:From:Date:In-Reply-To:From; b=uqjt8yfvSLU1x3NnSClFPr5yeFDaQeAFKz9CgLOz8n9dmnBnbBUKGQTX8iEwrO71Z SpKL12ePBl3popjHNZP9HNK4qxH+ngvjSafcCRPUJ7p6F45lGXVQX5xf25kpyHO9PH tNShAt13/2Z7AORlULPDwNcvSEZ6K3qmH1ZrOfXHqf6xJArWiVkVpiNJMvKxLRSaHF lSuDgF/7stY0T7++ChWRCXSyqpPUvgq9Ghs9II/P3IfDEiJGdsZ1j7hFHFL7l7B8Ah 6jSqdaWu7+V9IRaBrtM4P1ME1s+Tqc/KSoQ5K7+x44Fvhs5EWqD9JY3qKOZTXLrfHn sRdQGHb1RFZdg== Received: from [192.168.0.211] (novatech.home.cobb.me.uk [192.168.0.211]) by black.home.cobb.me.uk (Postfix) with ESMTPS id 3D016A0125; Thu, 9 Jan 2020 10:19:25 +0000 (GMT) Subject: Re: btrfs scrub: cancel + resume not resuming? To: =?UTF-8?Q?Sebastian_D=c3=b6ring?= , linux-btrfs@vger.kernel.org References: From: Graham Cobb Openpgp: preference=signencrypt Autocrypt: addr=g.btrfs@cobb.uk.net; prefer-encrypt=mutual; keydata= mQINBFaetnIBEAC5cHHbXztbmZhxDof6rYh/Dd5otxJXZ1p7cjE2GN9hCH7gQDOq5EJNqF9c VtD9rIywYT1i3qpHWyWo0BIwkWvr1TyFd3CioBe7qfo/8QoeA9nnXVZL2gcorI85a2GVRepb kbE22X059P1Z1Cy7c29dc8uDEzAucCILyfrNdZ/9jOTDN9wyyHo4GgPnf9lW3bKqF+t//TSh SOOis2+xt60y2In/ls29tD3G2ANcyoKF98JYsTypKJJiX07rK3yKTQbfqvKlc1CPWOuXE2x8 DdI3wiWlKKeOswdA2JFHJnkRjfrX9AKQm9Nk5JcX47rLxnWMEwlBJbu5NKIW5CUs/5UYqs5s 0c6UZ3lVwinFVDPC/RO8ixVwDBa+HspoSDz1nJyaRvTv6FBQeiMISeF/iRKnjSJGlx3AzyET ZP8bbLnSOiUbXP8q69i2epnhuap7jCcO38HA6qr+GSc7rpl042mZw2k0bojfv6o0DBsS/AWC DPFExfDI63On6lUKgf6E9vD3hvr+y7FfWdYWxauonYI8/i86KdWB8yaYMTNWM/+FAKfbKRCP dMOMnw7bTbUJMxN51GknnutQlB3aDTz4ze/OUAsAOvXEdlDYAj6JqFNdZW3k9v/QuQifTslR JkqVal4+I1SUxj8OJwQWOv/cAjCKJLr5g6UfUIH6rKVAWjEx+wARAQABtDNHcmFoYW0gQ29i YiAoUGVyc29uYWwgYWRkcmVzcykgPGdyYWhhbUBjb2JiLnVrLm5ldD6JAlEEEwECADsCGwEG CwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAhkBBQJWnr9UFRhoa3A6Ly9rZXlzLmdudXBnLm5l dAAKCRBv35GGXfm3Tte8D/45+/dnVdvzPsKgnrdoXpmvhImGaSctn9bhAKvng7EkrQjgV3cf C9GMgK0vEJu+4f/sqWA7hPKUq/jW5vRETcvqEp7v7z+56kqq5LUQE5+slsEb/A4lMP4ppwd+ TPwwDrtVlKNqbKJOM0kPkpj7GRy3xeOYh9D7DtFj2vlmaAy6XvKav/UUU4PoUdeCRyZCRfl0 Wi8pQBh0ngQWfW/VqI7VsG3Qov5Xt7cTzLuP/PhvzM2c5ltZzEzvz7S/jbB1+pnV9P7WLMYd EjhCYzJweCgXyQHCaAWGiHvBOpmxjbHXwX/6xTOJA5CGecDeIDjiK3le7ubFwQAfCgnmnzEj pDG+3wq7co7SbtGLVM3hBsYs27M04Oi2aIDUN1RSb0vsB6c07ECT52cggIZSOCvntl6n+uMl p0WDrl1i0mJUbztQtDzGxM7nw+4pJPV4iX1jJYbWutBwvC+7F1n2F6Niu/Y3ew9a3ixV2+T6 aHWkw7/VQvXGnLHfcFbIbzNoAvI6RNnuEqoCnZHxplEr7LuxLR41Z/XAuCkvK41N/SOI9zzT GLgUyQVOksdbPaxTgBfah9QlC9eXOKYdw826rGXQsvG7h67nqi67bp1I5dMgbM/+2quY9xk0 hkWSBKFP7bXYu4kjXZUaYsoRFEfL0gB53eF21777/rR87dEhptCnaoXeqbkBDQRWnrnDAQgA 0fRG36Ul3Y+iFs82JPBHDpFJjS/wDK+1j7WIoy0nYAiciAtfpXB6hV+fWurdjmXM4Jr8x73S xHzmf9yhZSTn3nc5GaK/jjwy3eUdoXu9jQnBIIY68VbgGaPdtD600QtfWt2zf2JC+3CMIwQ2 fK6joG43sM1nXiaBBHrr0IadSlas1zbinfMGVYAd3efUxlIUPpUK+B1JA12ZCD2PCTdTmVDe DPEsYZKuwC8KJt60MjK9zITqKsf21StwFe9Ak1lqX2DmJI4F12FQvS/E3UGdrAFAj+3HGibR yfzoT+w9UN2tHm/txFlPuhGU/LosXYCxisgNnF/R4zqkTC1/ao7/PQARAQABiQIlBBgBAgAP BQJWnrnDAhsMBQkJZgGAAAoJEG/fkYZd+bdO9b4P/0y3ADmZkbtme4+Bdp68uisDzfI4c/qo XSLTxY122QRVNXxn51yRRTzykHtv7/Zd/dUD5zvwj2xXBt9wk4V060wtqh3lD6DE5mQkCVar eAfHoygGMG+/mJDUIZD56m5aXN5Xiq77SwTeqJnzc/lYAyZXnTAWfAecVSdLQcKH21p/0AxW GU9+IpIjt8XUEGThPNsCOcdemC5u0I1ZeVRXAysBj2ymH0L3EW9B6a0airCmJ3Yctm0maqy+ 2MQ0Q6Jw8DWXbwynmnmzLlLEaN8wwAPo5cb3vcNM3BTcWMaEUHRlg82VR2O+RYpbXAuPOkNo 6K8mxta3BoZt3zYGwtqc/cpVIHpky+e38/5yEXxzBNn8Rn1xD6pHszYylRP4PfolcgMgi0Ny 72g40029WqQ6B7bogswoiJ0h3XTX7ipMtuVIVlf+K7r6ca/pX2R9B/fWNSFqaP4v0qBpyJdJ LO/FP87yHpEDbbKQKW6Guf6/TKJ7iaG3DDpE7CNCNLfFG/skhrh5Ut4zrG9SjA+0oDkfZ4dI B8+QpH3mP9PxkydnxGiGQxvLxI5Q+vQa+1qA5TcCM9SlVLVGelR2+Wj2In+t2GgigTV3PJS4 tMlN++mrgpjfq4DMYv1AzIBi6/bSR6QGKPYYOOjbk+8Sfao0fmjQeOhj1tAHZuI4hoQbowR+ myxb Message-ID: <654bf850-65bf-65f5-2ed2-90a0d4058e74@cobb.uk.net> Date: Thu, 9 Jan 2020 10:19:24 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 09/01/2020 10:03, Sebastian Döring wrote: > Maybe I'm doing it entirely wrong, but I can't seem to get 'btrfs > scrub resume' to work properly. During a running scrub the resume > information (like data_bytes_scrubbed:1081454592) gets written to a > file in /var/lib/btrfs, but as soon as the scrub is cancelled all > relevant fields are zeroed. 'btrfs scrub resume' then seems to > re-start from the very beginning. > > This is on linux-5.5-rc5 and btrfs-progs 5.4, but I've been seeing > this for a while now. > > Is this intended/expected behavior? Am I using the btrfs-progs wrong? > How can I interrupt and resume a scrub? Coincidentally, I noticed exactly the same thing yesterday! I have just run a quick test. It works with kernel 4.19 but doesn't with kernel 5.3. This is using exactly the same version of btrfs-progs: v5.3.1 (I just rebooted the same system with an old kernel to check). As Sebastian says, the symptom is that the file in /var/lib/btrfs shows all fields as zero after the cancel (although "cancelled" and "finished" are both 1). In particular, last_physical is zero so the scrub always resumes from the beginning. With the old kernel, the file in /var/lib/btrfs correctly has all the values filled in after the cancel so the scrub can be resumed. Graham