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_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 606D5C2D0DB for ; Thu, 23 Jan 2020 13:58:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26D442077C for ; Thu, 23 Jan 2020 13:58:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="Hy3sK4xo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726968AbgAWN6H (ORCPT ); Thu, 23 Jan 2020 08:58:07 -0500 Received: from mout.gmx.net ([212.227.17.22]:57981 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726729AbgAWN6H (ORCPT ); Thu, 23 Jan 2020 08:58:07 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1579787878; bh=+uTmqEfbzugD/hMxXUPSzY3h90bf36rJGLArwFN1gVQ=; h=X-UI-Sender-Class:Subject:To:Cc:References:From:Date:In-Reply-To; b=Hy3sK4xozKUMfaDno6D9l7MWHAWxG2OiHVzLB4o1HScrNq8u6UVCsKPUbz5O/l0ql gXs94w+abJVQD1u73+Py9B2mXQy4e3W0m/2s6IWlONaFDwf2DsQvWjbzz1ohBCsMoI mbW4P1iBdodumab6rI37A4GUCg37M+J+pzNrz8YA= 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 1N79yG-1jfqMD3XVE-017SJD; Thu, 23 Jan 2020 14:57:58 +0100 Subject: Re: [PATCH] btrfs: scrub: Require mandatory block group RO for dev-replace To: fdmanana@gmail.com Cc: Qu Wenruo , linux-btrfs , Filipe Manana References: <20200123073759.23535-1-wqu@suse.com> 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: Thu, 23 Jan 2020 21:57:53 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Pa16pgGaHGbOXqZxkXY2IfTPiDCUxcTgJ" X-Provags-ID: V03:K1:+QZO0uTwsm13Deka9Yo0PR5uV5nx9quo/reuGS+wFWcl4MiCA0t qUCWKTR3mwTAzwk5nLO7E/4VISyBtvacTOxyBlXqNW2MVyvEqifGBH09yJJ5Kuiy1PV8RQy hzKlO6Fii3Hc9ygg6aZNjoX4ZZkm3FyjN+G6C5xfm4kHVTnqNsde013+J8uOFYav2vLBCCF lxnGimnqI6FShRKPQqwCA== X-UI-Out-Filterresults: notjunk:1;V03:K0:1EfoQ7g1fXM=:jZ4/YVp3UaNktT4IDjutx5 ZUN7f0HBvp2Non/hmFOfQqg4Ql19Z7wt2Rn6PxsUE6Dwjy5C5c3PtnLAK7aFhtsarkuEqCegU WIfMedH24K4ZfCAecbLEUblH8syGpf4q7DDAaMMibuzc6Jnnq1657EdaHs1fbmAGmIUjCpHlF hQN8Al8lqEHCrs65fDAF/iQZcZgjzBg65wEyMbOpS2ry1K04j4a1SJRaVUJhs2bcgKUy0BtXA E9U21o/A5cwU0veVGIgRcnUzuKPKh8iRVX+xr4+md7DzyL3L0mC1XK1cs+fEGo1ikPX/6Wws8 6vawrRUt807QufHXDGzPMzOUw8VuVWpvEQ8rgttaUrJpVLsO1651lWwXMIwpWL15A/aevgNBF BRIsQ+wlKoerCfXYkm+UwrW9SppkE5T2EageU1myH/31GrWZvz3PtIsOuxuSo31V8A79VZyqy 7UmVFsaCFSi9VYuL0GklHPelcErNn5J0AEXpx+jzulPgVxtMW06u42Xl/gaLmSvGFl5piZo5H 33C7HFXy+tYMjfSVnFa2AJBCxRLCkLTnySkITnrwLn7gp0Qdid5zI5axLsFNQY7p//r81iMgS /R2i0XNc0DH8l/rOQxl3x0LLkA1alsLMX+8yr4e5kcfe04c9Eg/IFEt6ZfBJBLoj10+V1UPXW ohYpob7W5e90wP6ecVSM9O6RccOMP+P5EGke/jPTenbqMpWdnJNdHf71S8YtQxZHCRSnm9TEO Q0C7Y+fVNk/vLxghHxL55BTI03GRqDcB7slDKM6XBeryx4cdCiko3haQY4Jx0uPo0xebfTPG4 Vt60FSY+2/iCH/5BASIwBn9SJqs08HO8gp3uy9mmT9RDpwUozOwB+WcXXaWu238jX6z0blU4F yH55aVQqVFDAV12sEx4nFwmtVFsfe8tBKfVKUm+Uw16XxdGZbORoYWfXneOWed6yB331khYAd ABr6hw8DHG7sQbSa8Z64YmJuYC9whi07bx9ucZ3U/O6YQT309YelCpOHBTzZhIW3lwkK/90VF zwpHfhHh4+WEU7lHytTs8serCDfVbsbywKEltJm/acwfxygDAfxhrWqLRaIrDhcZh0FeRxK04 g7VKQy1KXV+yd0r+dkco7CkY2zbYc3fPk6AP++Dh489KSDigepNS4VB7iLXkwfMD+kB+qn2j7 E05Lg1qF7DWJqG6PUVVyrhIM+gQ5t19zCW+o/A5TV5NZnuKfuaSb24z/ksISCIim/XSkp2Ftp G2mk3QfBhNPs4X/QG 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) --Pa16pgGaHGbOXqZxkXY2IfTPiDCUxcTgJ Content-Type: multipart/mixed; boundary="XLwIrUb3kbIam3WBPxlD3yi9YkzDmzEjD" --XLwIrUb3kbIam3WBPxlD3yi9YkzDmzEjD Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2020/1/23 =E4=B8=8B=E5=8D=889:49, Filipe Manana wrote: [...] >> This btrfs_wait_nocow_writers() is not just triggering ordered extents= >> for nocow. >> It waits for the nocow_writers count decreased to 0 for that block gro= up. >> >> Since we have already marked the block group RO, no new nocow writers >> can happen, thus that counter can only decrease, no way to increase. >> >> There are several cases involved: >> - NoCOW Write back happens before bg RO >> It will increase cache->nocow_writers counter, and decrease the >> counter after finish_oredered_io(). >=20 > Nop. nocow_writers is decremented after creating the ordered extent > when starting writeback (at run_delalloc_nocow) - not when completing > the ordered extent (at btrfs_finish_ordered_io()). Oh, right. The dec part still happens in run_delalloc_nocow(). So the wait_ordered_roots() call is still needed. Thanks, Qu > Same applies direct IO. >=20 > Thanks >=20 >>> >> >=20 >=20 --XLwIrUb3kbIam3WBPxlD3yi9YkzDmzEjD-- --Pa16pgGaHGbOXqZxkXY2IfTPiDCUxcTgJ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAl4ppmEACgkQwj2R86El /qiPPwgApDc7KEjoixOjHodPqoTuEabJbathvR1jAC5D8Lcilr8tvxN+q6xZfqvM CnjsNTlN/98WmbIP7MjjKz0IVHJ5n3ZC/+pGpuI5CB5BGp7/dqaBW7eMHgSbKOFC oG2L4pM6pIwZ7Z1J7X80u+M7IpvJN97CUIQTP1PWSpTkoYIVQqrqCLxA27/aseoa JrLpeEl62YQF1KDy3pUY0h6JpivAYyCPTvvBjR9qXq7Bwj8Sojzyj5KwGDCk7U+X OJir2mvGpc/pz2Xig5K0QN2gJw1nkcyAxC4/xPiobtQ6QZjuEIMo10nCsCrXrxga UvY4pObHLUlUyrdnte4PWV0uVKF6Fg== =bVDs -----END PGP SIGNATURE----- --Pa16pgGaHGbOXqZxkXY2IfTPiDCUxcTgJ--