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,URIBL_BLOCKED,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 ECA60C2D0A3 for ; Sat, 7 Nov 2020 00:04:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72D8D206C0 for ; Sat, 7 Nov 2020 00:04:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="fvNGE2Hb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728059AbgKGAEx (ORCPT ); Fri, 6 Nov 2020 19:04:53 -0500 Received: from mout.gmx.net ([212.227.15.15]:47105 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727257AbgKGAEw (ORCPT ); Fri, 6 Nov 2020 19:04:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1604707489; bh=V2B6mI5g8IjsFd8H7lZrvXibxbc1HIEZzWA49xF2oOc=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=fvNGE2HbBVd0nWfcuwkNCMpkop4u3S1zaDAIbaZNtAHT71TGGA2bsuT0qYTEsbpxc rV9Yo9a1wAWz709wyeixl+NUKBSbC2l4Sow9M6qhGdnsUuIZ7A1Hrhd+v/zUA9n7OB pdJtF9A2raIhLLK0ypvkTXGvov4er/N1wZt70OWI= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.com (mrgmx005 [212.227.17.184]) with ESMTPSA (Nemesis) id 1MkHMZ-1jux8z3TU9-00kk0k; Sat, 07 Nov 2020 01:04:49 +0100 Subject: Re: [PATCH 11/32] btrfs: disk-io: make csum_tree_block() handle sectorsize smaller than page size To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org, Goldwyn Rodrigues , Nikolay Borisov References: <20201103133108.148112-1-wqu@suse.com> <20201103133108.148112-12-wqu@suse.com> <20201106185836.GS6756@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: <746bb53e-8a71-67a0-6d93-7c6e126670ea@gmx.com> Date: Sat, 7 Nov 2020 08:04:44 +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: <20201106185836.GS6756@twin.jikos.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:NOLsE4s317wXT1utyHsdEP1WdQELfFtadG9waZp+gbbOcAC/xVn jG4b10CcVHAmScrIiVtyDa4de2LZzd7P0WEvOsRQ2fMFGFyF6A9zWbamVufQJzX/a98qm3q pjqHIMJl8QzLZYhjms8CWU0bKCZbVTAMNAuySg0Alg/HzMrxZ56WkDe+sTC34U2q+SGpkGt LurdloehyksXGWSxYWIfQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:cfduYm6tuxg=:IAwzGUx9tdxF07BRisLsGx oCDBfuAo0zCQ8d82xfQWw2eCWcAOuzGHMLixamuwnur1owq39Y2kty7dSSXELsoyyyxrsncQC B4RLxWTDWb758Q+TLyZ9Dr3S4JuJiMc6LICkA4ROeWXS6hPW5ad3pItmV5ketkuVTx3kedsDv qyLdBJsQ69XaKslsRcudtmqmTa9ROFtotz0u7u66G7et9Fr87WPHJafNi4mDPQso5twmvxrpj /ysnVPApJXAD9LY4jf9V/K2pdv8Ej7af15sjR94ZRAi0KtIoLTyPl0LV53Gt1rR53cSnY/xow ROJFq4Cmo5gbfberch5G73smdeiplIu4sQ6UygL0ng7ksNjq99MiWKdb+ivCLzw+tKleU3512 JPKTcQ+Eer8tzCX2mr0EQKnVNaAIMkaLzTOsjVjaoMN4bIuYqxhvGuMBRs0YJw77DIFGD0pA5 hj7Q8es+28hPK91kpzGQA+zLXDSKx+YVQAteZzP+iVe4M+5PsUTMvZQy7A0T+ScBQ6tMxyqW4 yw6iObGfZ3/aobVpHZzgKzQkDmELaA8yCfdkCdeI0ce/Y8rr+ANsxN327RW3gICdOUzuSiAX+ B2cXWDhkBakhr59wRhxCaeMl6RpyhJvDLDaSbirtxttb+ABHZri5kU2oJptQ9/GU5gsNFeDnh T0m/zLlvXalZIy6EQBXA+10UihGXF237AfLBL1pQdVKpJ9flHrxyuTw1aoHJCGAaC0+0MtFWl qPEpl9ivttSFxxKHZ6c0GNVak8hGJHZOMTvW6IUEqr7ozdZI014g7XvU6arj+huwBc1A/8TCR 7IMLOaMeyYGYbANxAMR8EImwqZLr+Ev5kGTPnzI+TkkkdRFqtywff+cZbOLwg5YyLqdU/whxt eVSNt2K29ZdiaCgNhelg== Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 2020/11/7 =E4=B8=8A=E5=8D=882:58, David Sterba wrote: > On Tue, Nov 03, 2020 at 09:30:47PM +0800, Qu Wenruo wrote: >> For subpage size support, we only need to handle the first page. >> >> To make the code work for both cases, we modify the following behaviors= : >> >> - num_pages calcuation >> Instead of "nodesize >> PAGE_SHIFT", we go >> "DIV_ROUND_UP(nodesize, PAGE_SIZE)", this ensures we get at least one >> page for subpage size support, while still get the same result for >> regular page size. >> >> - The length for the first run >> Instead of PAGE_SIZE - BTRFS_CSUM_SIZE, we go min(PAGE_SIZE, nodesize= ) >> - BTRFS_CSUM_SIZE. >> This allows us to handle both cases well. >> >> - The start location of the first run >> Instead of always use BTRFS_CSUM_SIZE as csum start position, add >> offset_in_page(eb->start) to get proper offset for both cases. >> >> Signed-off-by: Goldwyn Rodrigues >> Signed-off-by: Qu Wenruo >> Reviewed-by: Nikolay Borisov >> --- >> fs/btrfs/disk-io.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c >> index 1b527b2d16d8..9a72cb5ef31e 100644 >> --- a/fs/btrfs/disk-io.c >> +++ b/fs/btrfs/disk-io.c >> @@ -211,16 +211,16 @@ void btrfs_set_buffer_lockdep_class(u64 objectid,= struct extent_buffer *eb, >> static void csum_tree_block(struct extent_buffer *buf, u8 *result) >> { >> struct btrfs_fs_info *fs_info =3D buf->fs_info; >> - const int num_pages =3D fs_info->nodesize >> PAGE_SHIFT; >> + const int num_pages =3D DIV_ROUND_UP(fs_info->nodesize, PAGE_SIZE); > > No, this is not necessary and the previous way of counting pages should > stay as it's clear what is calculated. The rounding side effects make it > too subtle. If sectorsize < page size, then num_pages is 0 but checksum > of the first page or it's part is done unconditionally. You mean keep num_pages to be 0, since pages[0] will also be checksumed unconditionally? This doesn't sound sane. It's too tricky and hammer the readability. Thanks, Qu > >> SHASH_DESC_ON_STACK(shash, fs_info->csum_shash); >> char *kaddr; >> int i; >> >> shash->tfm =3D fs_info->csum_shash; >> crypto_shash_init(shash); >> - kaddr =3D page_address(buf->pages[0]); >> + kaddr =3D page_address(buf->pages[0]) + offset_in_page(buf->start); >> crypto_shash_update(shash, kaddr + BTRFS_CSUM_SIZE, >> - PAGE_SIZE - BTRFS_CSUM_SIZE); >> + min_t(u32, PAGE_SIZE, fs_info->nodesize) - BTRFS_CSUM_SIZE); > > For clarity this should be calculated in a temporary variable. > > As this checksumming loop is also in scrub, this needs to be done right > before the unreadable coding pattern spreads. > > Also note that the subject talks about sectorsize while it is about > metadata blocks that use nodesize. >