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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 D8619C4361A for ; Sat, 5 Dec 2020 02:57:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A423522DFA for ; Sat, 5 Dec 2020 02:57:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726210AbgLEC5L (ORCPT ); Fri, 4 Dec 2020 21:57:11 -0500 Received: from mout.gmx.net ([212.227.17.22]:55871 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725300AbgLEC5L (ORCPT ); Fri, 4 Dec 2020 21:57:11 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1607136936; bh=MB/mcW0rWiKZ1MktW+tptKi/5XGJoGblfBt301xEC6M=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=kGIAg8xqn8tD+qSOiiefddhkij/Uqsnhm2owa1wBqCHeH3NBxv+XUsnyp7Gn3Q3FT APq10sPJ8rwRuckuhDrGhbiANzwJebBDfgDHcIHeZjvHgF3B3tnbqBimnc2kMj/9va 1yn/lOTX+N90fyGJ7aunxK4pt09NQIVcDrsq8lpE= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.com (mrgmx105 [212.227.17.174]) with ESMTPSA (Nemesis) id 1MKsj7-1kStXm465V-00LC26; Sat, 05 Dec 2020 03:55:36 +0100 Subject: Re: [PATCH] btrfs: qgroup: don't try to wait flushing if we're already holding a transaction To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org References: <20201204012448.26546-1-wqu@suse.com> <20201204172853.GX6430@twin.jikos.cz> 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: Date: Sat, 5 Dec 2020 10:55:32 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201204172853.GX6430@twin.jikos.cz> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="WLMZ0ELmePdc7Qaec9Ul02Az8XOMWqxUB" X-Provags-ID: V03:K1:Ngj0xiNE/cFahLFVTjAlcCxjLmOrb1KshtPnUExdNdh9pamAFeO flkR8ld1I/C+zOnTgp2Cvr1tCF+2wbq2/WfCX+loefHBnorYZp6gmm34VBzsoQAffl1aVR7 3PhWQv8FUnbGVOBfU982GfJBoK3dB0vcNJ/UhLx4UfRJKXnYCnRX6m/2D8+DyrGhlRI4G0g LfqpRGI5gYE+KygR4OQLw== X-UI-Out-Filterresults: notjunk:1;V03:K0:Z0+urlVvvng=:eabXuTaRufLi0glosvYjyC uyFnCUta9t7wadTL0gG8qAmNcyrth+wrR28r6bTf81+xbriKBgxBaXImUkA+dtHMl5b+ZuTAp d70mFe6bKSB+u+W7gNmu07VYL81oV1SS6JauS0HhcfjvPGKZ4hNCBILSBuwCy4cwrYw5SOeDl rqlB+ozjwG0iVDcnMyZG9+J3Hnz7dEVTf0HYoeRJPijPS4hSUcqTmfj2v2fg4RciGGyv5UMYD EQQOwI0/lpkPhZjwnq1BWyYXFj+bXT6iHPvPi2TW/K5MKRR/Lz/EKKb9UIqbc+VcT09da2KmB 55iF4U9gdqS52mzPWL5KCSLcoChSXGrJ5d2+SUWZYHihEgPlzlHNm4v17BVfIwk+x1RidXe6O 5dY48G1CICDoKpaL10SFNhLC1VEzIRdzcFyHZE9R1ClRmuzY8RO4vAgf5BPZMyExw2nDV/8uZ +faSWGhXCw8KjmfVF5KqQe/Ues71qmBe+FYGkAI/M3EUN8zUHHskkqVB2jFtc7ek3LG09OL3g 1dTayYypCihyKhSDTI8rm/x7fZwT6gt9Ne2qv3cBTlzmRxy5cQWLTgWA6sHM+uZRJg14vTMXF yGZ6GNuj9u6RuI0ral/Z8JGBPj3jWsRo74OMjqqG11EjK3uD2qubF5ksRK0rt7JcDVzyCo1mE FTkE1CF4oq7988vgvoUDIvzVaA37NYtY1a6wWIfvM0d4EwUjNZsj0hrNBBIPX9jscbE+6fSff Ke7Xpl/V6ZfqZlAtQqwY+oqWkovHNiXryR1Nx4MVzQ3te0KJZBzKY6nFTzqwirECmmGwjMRIO kBHMTmnzh7RYJ8/sceuZLmKb2Lj/1mKFLcgHIAedwbRTIHoF3i35ArWO9Ym5n3rE0y0vIclYq Df/cjixAC0yBIgW8ry7Q== Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --WLMZ0ELmePdc7Qaec9Ul02Az8XOMWqxUB Content-Type: multipart/mixed; boundary="6KvS0mg002PywmXogZZz3GbPeen6ycxkG" --6KvS0mg002PywmXogZZz3GbPeen6ycxkG Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2020/12/5 =E4=B8=8A=E5=8D=881:28, David Sterba wrote: > On Fri, Dec 04, 2020 at 09:24:47AM +0800, Qu Wenruo wrote: >> There is a chance of racing for qgroup flushing which may lead to >> deadlock: >> >> Thread A | Thread B >> (no trans handler hold) | (already hold a trans handler) >> --------------------------------+-------------------------------- >> __btrfs_qgroup_reserve_meta() | __btrfs_qgroup_reserve_meta() >> |- try_flush_qgroup() | |- try_flushing_qgroup() >> |- QGROUP_FLUSHING bit set | | >> | | |- test_and_set_bit() >> | | |- wait_event() >> |- btrfs_join_transaction() | >> |- btrfs_commit_transaction()| >> >> !!! DEAD LOCK !!! >> >> Since thread A want to commit transaction, but thread B is hold a >> transaction handler, blocking the commit. >> At the same time, thread B is waiting thread A to finish it commit. >> >> This is just a hot fix, and would lead to more EDQUOT when we're near >> the qgroup limit. >> >> The root fix would to make all metadata/data reservation to happen >> without a transaction handler hold. >> >> Signed-off-by: Qu Wenruo >=20 > Added to misc-next, thanks. >=20 Sorry, forgot the fixes tag: Fixes: c53e9653605d ("btrfs: qgroup: try to flush qgroup space when we get -EDQUOT") Mind to add that in the branch? Thanks, Qu --6KvS0mg002PywmXogZZz3GbPeen6ycxkG-- --WLMZ0ELmePdc7Qaec9Ul02Az8XOMWqxUB Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAl/K9qQACgkQwj2R86El /qh/1Qf/Yk7J5PiYM9zZURzc5cdc/zey1CF1pR4BDhntwTZrhHlhUbWx7DUwWSgs lvNI9khljFZnhXBajiLf2GHyR7PQIz+nPwr2KYnyd4aemlcC2iBb3DJf/JRV7Vx1 kuFr8MYSaFzOzzTJgCY2FblMBYMPfRWqeSrRxqPM3u3YpJT6m9KggTJop+4fTJ1L RxpqaAhZQq11F2dP4RX+FKaohjKUlrWCPWcrzBoq8rwg6ufZ6OulUFiZ+7msPAJv klhBPNgb8PeL/9dXMpzZIGbuTu2BydYSEw6onI9DlUCEV4f5ml/15LbH8KS3n8NR U5o/isZXmb53hAZCtxmm4GzxR2yVUw== =qupI -----END PGP SIGNATURE----- --WLMZ0ELmePdc7Qaec9Ul02Az8XOMWqxUB--