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=-11.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 6F292C43461 for ; Mon, 14 Sep 2020 08:22:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08A6620EDD for ; Mon, 14 Sep 2020 08:22:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="dNEJRfkq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726230AbgINIW5 (ORCPT ); Mon, 14 Sep 2020 04:22:57 -0400 Received: from mout.gmx.net ([212.227.17.21]:38909 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726249AbgINIWw (ORCPT ); Mon, 14 Sep 2020 04:22:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1600071762; bh=w9/bKl4l0gm6TaZN4ABpgZKAIYwVaJjqbn/9BpZuoqE=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=dNEJRfkqbSHsy7BBBsWA2Jehz2uZALJon67uamoJcXcjz5hkO52wH3G9Mwafswhp8 IVjdsTaD55ck5r7dH2TY/pw8hrwYwJWs8Ti+wrvcS7gX2Siovr8luAzhFgpxUapU7z FPRBCbJ3QunQUKZVEOEmcWPwxVZp/1M6BgqFNVYk= 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 1MtfNf-1kVPtV0eTf-00v4OP; Mon, 14 Sep 2020 10:22:42 +0200 Subject: Re: [PATCH 03/10] btrfs: Simplify metadata pages reading To: Nikolay Borisov , linux-btrfs@vger.kernel.org References: <20200909094914.29721-1-nborisov@suse.com> <20200909094914.29721-4-nborisov@suse.com> <7a1ae6a0-30d9-63de-f3f9-2b6f3c9653f2@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: <81ec5378-3ed0-7cfb-eab1-93c958fa426b@gmx.com> Date: Mon, 14 Sep 2020 16:22:39 +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: <7a1ae6a0-30d9-63de-f3f9-2b6f3c9653f2@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:w3WJDfPwtRXhQjt4qQu2CR+CpQ5pG//SZsTDguHFpJa3Fx9h7HG 6wALGuL2rzNAxWGbLBzIgXD4Nn7UY2huN7sPVPeIgCLs9e3qezlkzJrTH3gcPmuHgBkyLXb 7ZG2saRxLQoySprC7J2eW/xSTNbEj/cetlz2WdpVOw5eU1lMglEXOo1bnVz9TrW3ygKmEuE wODhs6JXdSKzvINJwy5pw== X-UI-Out-Filterresults: notjunk:1;V03:K0:iYmASMgrghA=:SpAyugTKjGV09RebBE8NiH Q6BAPmVu5NzaScGOM8vqcfxj8ZtGul7FnNqDVta3Z7PoxtztaKm0moX3R1QjXdfvJDeEJDSnV fjGtx5XEVhOk7Oo4pufsvZQMs0AmRr++qZpS8kHEg551lYUPbTWiRizdLyE7mPyoN7J+BTvcm HjanTPn1Vg2ukqAiPON9QalnkpdHyK4qaCBHMK2/8jjKdVSmfnIMIudtuFDko/+l11wh9y0UX W+3oSFSXGGc2odjYo1N/0eZOd22S6B/rRlV7rZJbHZjEfRiJzTCKqLrOW2HmUGPeVlF/ag9PV kQcY9IZPuxCgeVwbbyQjRtRxDxFmrI5JhLEPMf7J4Y/t2MtQ/dd03mD1n9yO8RxptEioxwMro LggLNLC/Wg9i17v+H1314cCK1EYQbPxq6Bd2B8e//VX48VXDoQEoc6USmcNItRG86jDcCxSYZ vZCGbjlcr+YOe+j4nodLXGNTsDCDI5GkpLsA1dq0UTIQ65jmxzd/p3Tp5/liwIaQZMJEdgT03 PLxhd5/PolRBkK8hMn0oEXD8Pl+uega/7lsKicxIHlwnYhTY61oNDKbIcAslamho6slfxSAKC if0ExM6OM/dbhFJ0/99qVkHbxAu9aznJAaUDtT8/TqmG7J7+6Bsx1NQblGwIbayOzKyS10cq1 4iHq7Ll5Id+frkdvva4BLOTleFyPsLnsH5ICXgWTW7gPgFkbk/Lzbw2AQ2aNflJZiZEgXNYQ5 9zl/8CbZle0BfGpR4kui7hi4RxXTGpg1PvpSYhoiMCa4TkGCmRmT7oqUzACVtBZbC6WFPyVJc WzaDkX9PDLjaYfeen/XlmYP7pWMr6CmJmg0XynuA4ZGb4eb5QUhatlxnnNwx/1jXggy1v8vaH +cN9E+eSSN7ATzF4toEd1jRQj6Nqb9MCrcBMGcVJYhWXu3cP+MBk+UGfYPo88Gs2WzOuTgqMU 7f0PSGvP0/0+xQ8gaV3yFr1eJG/fULuEbMyMNCcxSfwFbZJDNN7D11DDuc7ijZ8+LY32bwpJX VX/OIin0YDYwl1jMjTXScqIXlkE/rmNtamYnWQpPk2vVeZf4qmd2dOiGBhATFl4P3accFKVB7 JUJZpO9FcAEy1bZhuhJXHmoWzIMccUOWR7wR2ZbH+nmN+0Siij0WmDr32PRYb1NJtqW81c3ek qD2y4dee7FSxqfbdQAkHKvRTjB6C1ukYY0o3OuxV+34izaPKTFHBs6cS80yDUPdVF3AdoRCew T3RpbeYUk6e0YVOkBTBZUH2plqctmsDgC1FpjvQ== Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 2020/9/14 =E4=B8=8B=E5=8D=884:08, Nikolay Borisov wrote: > > > On 9.09.20 =D0=B3. 14:20 =D1=87., Qu Wenruo wrote: >> >> >> On 2020/9/9 =E4=B8=8B=E5=8D=885:49, Nikolay Borisov wrote: >>> Metadata pages currently use __do_readpage to read metadata pages, >>> unfortunately this function is also used to deal with ordinary data >>> pages. This makes the metadata pages reading code to go through multip= le >>> hoops in order to adhere to __do_readpage invariants. Most of these ar= e >>> necessary for data pages which could be compressed. For metadata it's >>> enough to simply build a bio and submit it. >>> >>> To this effect simply call submit_extent_page directly from >>> read_extent_buffer_pages which is the only callpath used to populate >>> extent_buffers with data. This in turn enables further cleanups. >> >> This is awesome!!! >> >> And the code also looks pretty good to me. >> >> Reviewed-by: Qu Wenruo >> >> Just a note for further enhancement inlined below. >> >>> >>> Signed-off-by: Nikolay Borisov >>> --- >>> fs/btrfs/extent_io.c | 18 ++++++------------ >>> 1 file changed, 6 insertions(+), 12 deletions(-) >>> >>> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c >>> index ac92c0ab1402..1789a7931312 100644 >>> --- a/fs/btrfs/extent_io.c >>> +++ b/fs/btrfs/extent_io.c >>> @@ -5575,20 +5575,14 @@ int read_extent_buffer_pages(struct extent_buf= fer *eb, int wait, int mirror_num) >>> } >>> >>> ClearPageError(page); >>> - err =3D __extent_read_full_page(page, >>> - btree_get_extent, &bio, >>> - mirror_num, &bio_flags, >>> - REQ_META); >>> + err =3D submit_extent_page(REQ_OP_READ | REQ_META, NULL, >>> + page, page_offset(page), PAGE_SIZE, 0, >> >> It would be better to enhance the comment for submit_extent_page() of >> @offset. >> It's in fact btrfs logical bytenr. >> >> For metadata, page_offset(page) is also the btrfs logical bytenr so it'= s >> completely fine. >> But it can be different for data inodes, so it's better to make it more >> clear in the comment. > > How can it be different for data node? page_offset is always page->index > << PAGE_SHIFT, meaning it's the offset in the file that this page refers > to. I.e page 5 would refer to 20k. For data inode, its page_offset() is the file offset, not logical bytenr. Thanks, Qu > >> >> Thanks, >> Qu >> >>> + &bio, end_bio_extent_readpage, >>> + mirror_num, 0, 0, false); >>> if (err) { >>> ret =3D err; >>> - /* >>> - * We use &bio in above __extent_read_full_page, >>> - * so we ensure that if it returns error, the >>> - * current page fails to add itself to bio and >>> - * it's been unlocked. >>> - * >>> - * We must dec io_pages by ourselves. >>> - */ >>> + SetPageError(page); >>> + unlock_page(page); >>> atomic_dec(&eb->io_pages); >>> } >>> } else { >>> >>