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=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 61468C3F2D0 for ; Fri, 28 Feb 2020 08:41:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29AAD24695 for ; Fri, 28 Feb 2020 08:41:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="WPbN09qp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726359AbgB1Ilh (ORCPT ); Fri, 28 Feb 2020 03:41:37 -0500 Received: from mout.gmx.net ([212.227.17.22]:43531 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725877AbgB1Ilh (ORCPT ); Fri, 28 Feb 2020 03:41:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1582879288; bh=TdNes+75c1hh89dP0/XUyrszPizxUjTwDL4xGsIcODY=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=WPbN09qpF/8AS+BeLUBsFRBum7im9joYjqPvJy+0c9Y3TXHL48SpjfBDNdWF2I+jb pKRlLMB0K6YB1hOECj2h4a5ej/xG0x8dSojhqKyLLp0BGTJ11fZFqAtq+jUH6mFnKh pyOFcRGXBWlR8zOo3duPZmoYZlO7hQZjURaMkvng= 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 1MjS54-1jnqm52T9O-00kzIL; Fri, 28 Feb 2020 09:41:28 +0100 Subject: Re: [PATCH 2/4] btrfs: simplify tree block checksumming loop To: David Sterba , linux-btrfs@vger.kernel.org References: <4f450bbeec245479a3bc2b40d023d1979d622587.1582832619.git.dsterba@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: Fri, 28 Feb 2020 16:41:23 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <4f450bbeec245479a3bc2b40d023d1979d622587.1582832619.git.dsterba@suse.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ZmfEJ3DPv6rluK2IEI3H4Vq8ggc4NJPFl" X-Provags-ID: V03:K1:odEKCSz9/r9Xg2I4B2bWz2Zwhw0DiTkGkNG2txCSrxhgsuUa9Dq 6Uoaf/Bh26feXKX6BfzINuyhATN9MlwNyR8P7GGO1BbdftssspE++ElbQVln15iQNZIfkBG SckP7ygpEeZw+dwdcFM7M4zPZuV0zHRU7m/xYEt1LCaOSL4lV2+d3ZkBsZIxfxPvURbI3UM pdtmyvYnWUqpIO4TofscQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:nm3fF6fMNa8=:oXnSp8elF/t4Gp/+kEov5o PlKl+lcengnbFZGMNoRWx5yu5uVHCBe2gUREwfjsE2M6NAz47iqrU64VC6zpYdM2r6nxJC+q+ U47OMtKtIY4pfycYJFaJDP7p4HSW+eFYvQk5rzt79p7DwjSIOp7wemtWDLnMpQsUPYfgIUv0I QB1mxj440u7jMJYmRbxJnh7Gg6keVdg/Fwvcfcrc+AJxRgE/CH0TTlZnf76fOsfs6JJV+hcAA 0yf/bnQOS+lOPL5wPchjBfufNXhiiCK5VWJVhggSKqrIrvs1rE0/2t6U2mkjJB9OIPph3uM6m yHxHixCOwzzK/i/21WS/PartKyWTCWRE4gFkWQeidGWKNGPW8wPUWpkAuXnT3w3Pf6Nd3o7dt EFrzvyMeqC5QV3nFbbJ2P39W1oYX33ubuoru5ncZM11BIzvRHoPfzeLIYC7ppEr4VfTM4bYtS ybH8rV2SDKldl3bPVBzs/NkIeDFJGPv4mvsiZ0K6+H6PA7mzgqmXZeOg3qT/n0DjsTnlCQ8P7 Vg1qUPbBkXtzOmZKoea6Cc7KnyDcTuWVa1KB/5f7Yst+S6xmdMSDKwqbhQ4IHjLg6OXCRElRu 8KALfUmAY7Nunq6wnMUCHyBITj71jr8o73NN6mzfDMlOzC6cLcoWlEnf0LLUr4sWrZasjoXec xZdGMttedhhAF75OcWOZ4iRPE7mfD1N4agLbLugoAKKtZnNF8rcChc8zJrEMsp/OxIV4Gc5W2 tgNHJPoN71VN9iSQn6sCZKm4AtMcdna/kSN8bEaLfYZQezldfxWqMc/xMHwyoO6UMXm/aXjp4 ktSzHGqq0MdFN4EgjHKkuKuMRKd8QCdiVvu0FSI4MoKrAoBPFfHCA8uF1XLMg7TyLZemVZV26 GPflVPISLN3AOM8aU2r2ayyu82Qqbn9ydDMqDCH6e0etvq/Ti7XeqK+PaAM97bqkhem4m9XC2 PIvi+k4uUOYd4B2HVhbjdVqnZpkbyqDnPpGFtjyWGfOWq26MsDyV9LAOyMudBTbEi9CX/rGr/ +lAi/4kwy/0fAomHPdENS4+fieC0AqQuUo2t0A2YVkO9+dRGIdoxb4fDmIBB3j2TE/sqJXSB5 HEXdChWJCGcbRaw+lbHAzT7H9KSf1/UOd8Ma0x2yXjdkMeGkSdS72jw9DOHjVvtD+3dh+sjTv TdMRIgohzZ85rDbumYaAjWZh2Jhia09Qz+LwwmcJ9arzwANYfcMihjDXHbZtIxOgG/oBsMHjg S6vdzfLk/hg/1B2A5 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) --ZmfEJ3DPv6rluK2IEI3H4Vq8ggc4NJPFl Content-Type: multipart/mixed; boundary="lm576WCyOeJa6THeof6zfJF1pE2soeLcu" --lm576WCyOeJa6THeof6zfJF1pE2soeLcu Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2020/2/28 =E4=B8=8A=E5=8D=884:00, David Sterba wrote: > Thw whole point of csum_tree_block is to iterate over all extent buffer= > pages and pass it to checksumming functions. The bytes where checksum i= s > stored must be skipped, thus map_private_extent_buffer. This complicate= s > further offset calculations. >=20 > As the first page will be always present, checksum the relevant bytes > unconditionally and then do a simple iteration over the remaining pages= =2E The new operation looks much better. Reviewed-by: Qu Wenruo Thanks, Qu >=20 > Signed-off-by: David Sterba > --- > fs/btrfs/disk-io.c | 32 ++++++++------------------------ > 1 file changed, 8 insertions(+), 24 deletions(-) >=20 > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index 3952e4a2f3d7..5f74eb69f2fe 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -259,38 +259,22 @@ struct extent_map *btree_get_extent(struct btrfs_= inode *inode, > static int 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; > SHASH_DESC_ON_STACK(shash, fs_info->csum_shash); > - unsigned long len; > - unsigned long cur_len; > - unsigned long offset =3D BTRFS_CSUM_SIZE; > char *kaddr; > - unsigned long map_start; > - unsigned long map_len; > - int err; > + int i; > =20 > shash->tfm =3D fs_info->csum_shash; > crypto_shash_init(shash); > + kaddr =3D page_address(buf->pages[0]); > + crypto_shash_update(shash, kaddr + BTRFS_CSUM_SIZE, > + PAGE_SIZE - BTRFS_CSUM_SIZE); > =20 > - len =3D buf->len - offset; > - > - while (len > 0) { > - /* > - * Note: we don't need to check for the err =3D=3D 1 case here, as > - * with the given combination of 'start =3D BTRFS_CSUM_SIZE (32)' > - * and 'min_len =3D 32' and the currently implemented mapping > - * algorithm we cannot cross a page boundary. > - */ > - err =3D map_private_extent_buffer(buf, offset, 32, > - &kaddr, &map_start, &map_len); > - if (WARN_ON(err)) > - return err; > - cur_len =3D min(len, map_len - (offset - map_start)); > - crypto_shash_update(shash, kaddr + offset - map_start, cur_len); > - len -=3D cur_len; > - offset +=3D cur_len; > + for (i =3D 1; i < num_pages; i++) { > + kaddr =3D page_address(buf->pages[i]); > + crypto_shash_update(shash, kaddr, PAGE_SIZE); > } > memset(result, 0, BTRFS_CSUM_SIZE); > - > crypto_shash_final(shash, result); > =20 > return 0; >=20 --lm576WCyOeJa6THeof6zfJF1pE2soeLcu-- --ZmfEJ3DPv6rluK2IEI3H4Vq8ggc4NJPFl Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAl5Y0jMACgkQwj2R86El /qgNjAgAiv43xMINCXPvi+qRHG9wwy5+l4DdsGaAjkmlbxCYwwI4SF57E5afdwE/ /z8ShkByd9wNmYc1ufpibSVaSHxKay5Bg8CHPaufzQlFQ7PGc1DVnb0WcpoDc/cX tQ3B/o20zrCwMf+Wgl9PI0MwDXIz8A3Hr1OLXb3OUj1QzK/M2V8Wa9x9OUeJZV+O L/JrjwUZGDz6p5uRmp63sjCXOx1A7ap//sAdwSw6Q5w7viIQbYhbz2l6nZ2Y0Ruq 0OZoNqSCIw72oKUKVi6eEpWw/QOEyKapSUoy9xbDjs9Rvu87uuDQoQQxdnMTIow8 fEdnkvq5wEVKWnt3z+NXt1gziPNjxQ== =5nsK -----END PGP SIGNATURE----- --ZmfEJ3DPv6rluK2IEI3H4Vq8ggc4NJPFl--