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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, 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 E06D7C433DF for ; Sun, 5 Jul 2020 13:13:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B44B420739 for ; Sun, 5 Jul 2020 13:13:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="PZTbQ1AP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727843AbgGENNm (ORCPT ); Sun, 5 Jul 2020 09:13:42 -0400 Received: from mout.gmx.net ([212.227.17.21]:47437 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727062AbgGENNm (ORCPT ); Sun, 5 Jul 2020 09:13:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1593954819; bh=5LBT52pPuA6evP3bWw58hrw8ZVSCyPvb6UjcDWrLaKM=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=PZTbQ1AP1/IC/DQm6m4Vcei2243r87BRB+r3J408FF+C0OE1LTuHnFi2Lgrj7eAFL YHO12h+EamXT/pJ/Omdunxgt58FeGZn4lqD4KJ980OT+qKWpDW2uuEt28vFGlvbt4P tQuqsLR98kml1iP9CSgmskV3F1mCXmRDx6bD1xGM= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.com (mrgmx104 [212.227.17.174]) with ESMTPSA (Nemesis) id 1Mnpnm-1kh6Xw2WHi-00pKj3; Sun, 05 Jul 2020 15:13:39 +0200 Subject: Re: Balance + Ctrl-C = forced readonly To: Hans van Kranenburg , linux-btrfs@vger.kernel.org References: <42c9515d-7913-e768-84b1-d5222a0ca17d@knorrie.org> From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; prefer-encrypt=mutual; keydata= mQENBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAG0IlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT6JAU4EEwEIADgCGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCXZw1oQAKCRDC PZHzoSX+qCY6CACd+mWu3okGwRKXju6bou+7VkqCaHTdyXwWFTsr+/0ly5nUdDtT3yEVggPJ 3VP70wjlrxUjNjFb6iIvGYxiPOrop1NGwGYvQktgRhaIhALG6rPoSSAhGNjwGVRw0km0PlIN D29BTj/lYEk+jVM1YL0QLgAE1AI3krihg/lp/fQT53wLhR8YZIF8ETXbClQG1vJ0cllPuEEv efKxRyiTSjB+PsozSvYWhXsPeJ+KKjFen7ebE5reQTPFzSHctCdPnoR/4jSPlnTlnEvLeqcD ZTuKfQe1gWrPeevQzgCtgBF/WjIOeJs41klnYzC3DymuQlmFubss0jShLOW8eSOOWhLRuQEN BFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcgaCbPEwhLj 1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj/IrRUUka 68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fNGSsRb+pK EKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0q1eW4Jrv 0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEvABEBAAGJ ATwEGAEIACYCGwwWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCXZw1rgUJCWpOfwAKCRDCPZHz oSX+qFcEB/95cs8cM1OQdE/GgOfCGxwgckMeWyzOR7bkAWW0lDVp2hpgJuxBW/gyfmtBnUai fnggx3EE3ev8HTysZU9q0h+TJwwJKGv6sUc8qcTGFDtavnnl+r6xDUY7A6GvXEsSoCEEynby 72byGeSovfq/4AWGNPBG1L61Exl+gbqfvbECP3ziXnob009+z9I4qXodHSYINfAkZkA523JG ap12LndJeLk3gfWNZfXEWyGnuciRGbqESkhIRav8ootsCIops/SqXm0/k+Kcl4gGUO/iD/T5 oagaDh0QtOd8RWSMwLxwn8uIhpH84Q4X1LadJ5NCgGa6xPP5qqRuiC+9gZqbq4Nj Message-ID: <131421c2-1c2a-4b1b-8885-a8700992a77d@gmx.com> Date: Sun, 5 Jul 2020 21:13:34 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <42c9515d-7913-e768-84b1-d5222a0ca17d@knorrie.org> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="2jhxaXWb6m3DejvaxqD78y5o9C9X5KjUW" X-Provags-ID: V03:K1:z4KXCC/0coMbWIDm3wKhXoZ/c0UUJ6vh1qII18kqCfHCLpz8MzT zx+oVpAUksmZF3MGPfvKDgecjN1qQkYvti9spjiPlVuPpXEpiV5ghWj8yQiSsTU+bI4XIhT xqffHDD+6cE5lp7zar8vwbgJMBsonS3RFOyHLFsXGxDT7M0Oto+qIPftdjX/uHk7DGI4kK5 ia4VKbFhrzDZYTeB3nDCA== X-UI-Out-Filterresults: notjunk:1;V03:K0:PB2AGinU6HE=:rjBL1orpXN8Q+JhL31fpMo SuVSYIIeachxlfGyQexiITvJ79fmq58I1L/Il9doIiQWRtCGdJdNq1dnq8HrocPRpSub6tLao 4Gn2TliONIpMR/rV4xYSSe+aS68wWdBE6Mq2USPgkDEE2eviKziCpoA6BI7VEEmDJm/cAl0Po 9EKB1MAimR+czi3f5hwSqZO3yXNP6rmvnqDPe6N2DhenhfwWFovygc+ryQYNe/B7rOK4Q7yD/ J552nhHlJKvzDz4DwDC2kGtM6q3p1hAtkaxUspRACe16I19xuWHkWXvWGnVF8H5J0f5Y36U7x CJYl/Y33DUS99lntokbyf4YrdHj/rE5oHxwTsCpoIF2aqsfCKoN444xoxXzV8kqkTVDmOvd/Y mbIvHC3bHUkXV+hK9GNCJF621vhyzLdJ6t7if/gZ+UtlUQKUacNa8IBUDd3LWcJFzQRTZ6+V7 AhBF2KFB5OV1jH4aNAFBD/y9QZnWIX52J6JuSoCdvkPTnTRhKMrel1nyATfxeib4LyH2fIQ+N lvhTW7dE8Q/wXc7ckPsXDWhDl9pjnvV5VrPmmJ766PZoUe+GNoMn61t2WukM9gqFYMKy7VXVn kvYmU6auUx0ARx/zwN0CQftRawmFy9WfQLZK0Q9jcCjCrekkYUVc1F4vQNqzZmlajzqs/WWl5 40EyC+nON/SO1hcgiiN/cTRjytTSfx7pFYhAChXSt06Zl9hBSLz2ntF2LIUPG8ouA43JGYEsF W9mlIx6akoyh5ObtyPtUf9GUzpR8zIk8q1a3V7odD6HD5NCq2ylNFsSSIccBAv7maIIf8S+Tz en15O5oQ9RYCBJmN6h1hfEvaUlROci+UMEBxV1iDJSWVOOXTWQ+LPy1dZu1bANPccBzT2/Trz 82Gowy2MrmLHJJzpU4TXzGcA0W5XrWBQZtW+XpwaVhzwuwjgAwbRQVziDRuCywHnsyJh1FjpS A1YMask0HsVI0vdPLx0DsEIdCg6PcjG3buQ/+qFfxdzAzlP364lcmC337ItMptinxABVF0D04 Iq8cFsK1O3OP6FdbRvj2TN9g7Zg5a+0gN/K0peCO+GB/Wy5Yv/QoHg+r5jw6GH/qHuaQOhaT5 T9XKyHUXJp1/BWXiogmJw1KuMtiAN8xCZo8OJi3spA681vVTADXEpqiPytJ4aOkDDNgTycMmV luYTRViJu8NDhhV3ESdxAnfpN9mC7pPZzD1e0RY6FWKKvx+c4ZaYJTYeVZhKgd8QKn4H3jX/6 or10Xu7yeCNyzATGmDBoxoUf223oEwDzL0vM4KA== Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --2jhxaXWb6m3DejvaxqD78y5o9C9X5KjUW Content-Type: multipart/mixed; boundary="zmIwmiZ9R1yv800nTQFhofIWsaevF14da" --zmIwmiZ9R1yv800nTQFhofIWsaevF14da Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2020/7/5 =E4=B8=8B=E5=8D=888:49, Hans van Kranenburg wrote: > Hi, >=20 > This is Linux kernel 5.7.6 (the Debian package, 5.7.6-1). >=20 > So, I wanted to try out this new quicker balance interrupt thing, and > the result was that I could crash the fs at my very first try using it,= > which was simply doing balance, and then pressing Ctrl-C. >=20 > Recipe to reproduce: Start balance, wait a few seconds, then press > Ctrl-C. For me here, ~ 5 out of 10 times, it ends up exploding: >=20 > -# btrfs balance start --full /btrfs/ > ^C >=20 > [41190.572977] BTRFS info (device xvdb): balance: start -d -m -s > [41190.573035] BTRFS info (device xvdb): relocating block group > 73001861120 flags metadata > [41205.409600] BTRFS info (device xvdb): found 12236 extents, stage: > move data extents > [41205.509316] BTRFS info (device xvdb): relocating block group > 71928119296 flags data > [41205.695319] BTRFS info (device xvdb): found 3 extents, stage: move > data extents > [41205.723009] BTRFS info (device xvdb): found 3 extents, stage: update= > data pointers > [41205.750590] BTRFS info (device xvdb): relocating block group > 60922265600 flags metadata > [41208.183424] BTRFS: error (device xvdb) in btrfs_drop_snapshot:5505: > errno=3D-4 unknown -4 means -EINTR. It means during btrfs balance, signal could interrupt code running in kernel space??!! I thought when we fall into the balance ioctl, we're unable to receive/handle signal, as we are in the kernel space, while signal handling are all handled in user space. Or is there some config or out-of-tree patches make it possible? Is this specific to Debian kernels? At least I tried several times with upstream kernel, unable to reproduce it yet (maybe my fs is too small?) If it's config related, then we must re-consider a lot of error handling.= Thanks, Qu > [41208.183450] BTRFS info (device xvdb): forced readonly > [41208.183469] BTRFS info (device xvdb): balance: ended with status: -4= >=20 > Boom, readonly FS. >=20 > Hans >=20 --zmIwmiZ9R1yv800nTQFhofIWsaevF14da-- --2jhxaXWb6m3DejvaxqD78y5o9C9X5KjUW Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAl8B0f4ACgkQwj2R86El /qhAvwgAkb906pRhnK0Ob57DFleMo+jV3gvdL1xsLP2cm9ScLvDIZNJp7S7KHrf8 GudHcN8fWMbEh+FK/i8NTiUYF0vJamlziaoEVUbCyi2S/impFU/IVZTzV6Kkmsf/ 2yZPAcfZSPrPH1VFJAQzsE37EBkJdGV8SyIRlcrb3rdZkoULRKECdnX+Tt/yoa5M nxEo4h2x3BYznex5jbO2EVKUktZ2l3YVdEHQp0CldqfGuBSFurO+vgsftP2+dfgL sY7if7gwUJPabQoIcYrLZN1y3a+p4WWYVTouyTxwp7wzW9cFjH0IapprqD2atKMP jU0OuEJg+NgRthGuJs86Xm3OF6ZInQ== =zFyF -----END PGP SIGNATURE----- --2jhxaXWb6m3DejvaxqD78y5o9C9X5KjUW--