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=-8.0 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, 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 09150C433E0 for ; Thu, 18 Jun 2020 12:00:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C37B1206E2 for ; Thu, 18 Jun 2020 12:00:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="Qe1R/xsA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727928AbgFRMAh (ORCPT ); Thu, 18 Jun 2020 08:00:37 -0400 Received: from mout.gmx.net ([212.227.17.22]:37857 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725944AbgFRMAf (ORCPT ); Thu, 18 Jun 2020 08:00:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1592481626; bh=U5v9fPRV+n8wI7NB31R8sYVblzrc67jzxqSPJ6wBXFA=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=Qe1R/xsAYPLxDq3SshToMQcmDbekwzY22p6Bb4NZO7VeGpwC+BEgeJOYdB3yReiNc PLdOqoTxdIZu6/oc9Y4unLEQXN1i6/zU78ycpr3DPTWhlKk2EMLAP7/26qL7rcMY2J 0vPmY+VmSATZovrVGurANO9zPZj1VRL6ethVQtz0= 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 1N7zBb-1ipx2w48KR-0150Az; Thu, 18 Jun 2020 14:00:26 +0200 Subject: Re: [PATCH v3 1/3] btrfs: add comments for check_can_nocow() and can_nocow_extent() To: Johannes Thumshirn , Qu Wenruo , "linux-btrfs@vger.kernel.org" References: <20200618074950.136553-1-wqu@suse.com> <20200618074950.136553-2-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, 18 Jun 2020 20:00:22 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="FZzGN4dq0CguPJqQd3RNzM5rC9j7Pvzfn" X-Provags-ID: V03:K1:XTc9jTKpqAuW/sWdUTmtcqmcQ/ORPsVwy0Lfx9RKi6XEeiyZcv+ LVTNanItTQyzuBuMhcKQROIv6X1P+VJIeSFQftsjhTDXo9k22ChEIAnF7v8yB5U3wJMfXJU WR8VI8Frjbs+TXm7OA8P687UaWybyAoBqLQT2NgRWDga6p5uBFxXQgVk9HctQ+zSVX7Ngj4 MxiclBmNFluKNZ2SGkxKA== X-UI-Out-Filterresults: notjunk:1;V03:K0:vOsk7xdVLn0=:i6SQuwsr51BQnbK9RGkDCa IOBFKbkLuINT0gwXFDHn14B6MYcMA2GCwODlBGu4EtfT2yezYwgYDKfJW8VdmpGXEqw1wEiTZ 1ZRYk1JyVdpYL1S4F9tamWAbd8ujUYavAP+mrCrv0RxCOre+gyu1zFEKH4lcLquTHkBnom5TP Eh0dU9XIvkt85aNTD/vuokS/FPmvTUboCguxlLMzc25SKiARNmVxQeFqZU/a+/tGL9PBqjumZ 2RmSt+q7rBmvIkzOTPcuk/+E/EL07Owlrs91QoR3WuD9G4Ad/u2d9/nvGoYnbDwMEBbGGv6yu CGZyIzVt4Ndj6JJ0IgS2ibii7qSLJBizMREXLdBYxaplK94J/siq8eWX/IK1b6/c0guUr9Otj s08QWk3By56tZ1aiQetdHkM+yPjVwreH7m5ryTgUtzWh7fktYtAo8SNBS1qm/N57xutSmzLBv a7CIFgFVUD13CaYYSNANsdrTi7SmryjFiAR/1Nnc1U2M5jK96KhJa1bMFJ2ZZpN24rNKFWnT7 Yv6yqqyMRfmfWCHtvmhqmTprlVBcD9qRWdRdZ3VX3m9fk8yn7bD33mH522eu47Pkjwq4Wl1+N bAXq5a71IW7FOwFtzo6YeVE9Kf/LMpk2RLTYuZQ7/GxNk1gjUi5vqNkIyJdVevS59fmPwYfYs rQreZwWAPHQANVria8F309XlSDXOB5KBHH17OOzD22W2L8rARZ2o1gBICY8Z+/kCNLzKyCE1k BiaGfL58DaNPWFnsK73PuLV33Nk8EXdfyV816g5iT1PtjaL6wB4hu9EcwuSCbr3/8bJPscx6W AmvlTANN6eYgUGY97cnKKqUAnuiRzs6F3fGNwQLfYBwrUiBg98jFW3d4seF7qE2ngcLmqgwic 8ednFNPFww7HcgOhU4kb3Ot1dQ4np+ZsJ7Wf9BxrPcepydWYhnYBRH+WQPmHzF3k6wy09wBgl c2Fu/GbeutZBbrJjAS6MCTHh1kfglShZ+lhSkA/0hum0p6bUTJ3w/fyUt9gY2jD1voUrN+dqa NZszICl3ZL9kAATZYtTYyzk/JCA0oj5a1lis8ITy+h7+I3KYxz23BgeJ4H6PWk0u/y6FjH6Gb k3v0njml/69s6wnz0m07O7rPq+uQv5gWessqQLueoGOjL9vEfe6JsG1Q/ZwFQUM3x8Y5lnBOv 4eZn3B6YJR8WvoYzAL6WHO1iO4VRf3a3METE6SFIrd+Q7FlQxRDIPBo/mFcP29ji01OUVyqHV 1Mg2POTD3DlaLQ6aX 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) --FZzGN4dq0CguPJqQd3RNzM5rC9j7Pvzfn Content-Type: multipart/mixed; boundary="FdjruJuEVTaVjQKVdM3evktHpnsyDGxCE" --FdjruJuEVTaVjQKVdM3evktHpnsyDGxCE Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2020/6/18 =E4=B8=8B=E5=8D=887:57, Johannes Thumshirn wrote: > On 18/06/2020 09:50, Qu Wenruo wrote: >> These two functions have extra conditions that their callers need to >> meet, and some not-that-common parameters used for return value. >> >> So adding some comments may save reviewers some time. >=20 > These comments have a style/formatting similar to kerneldoc, can you ma= ke > them real kerneldoc? Mind to give an example? It must be a coincident to match some existing format. Thanks, Qu >=20 >> >> Signed-off-by: Qu Wenruo >> --- >> fs/btrfs/file.c | 19 +++++++++++++++++++ >> fs/btrfs/inode.c | 19 +++++++++++++++++-- >> 2 files changed, 36 insertions(+), 2 deletions(-) >> >> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c >> index fccf5862cd3e..0e4f57fb2737 100644 >> --- a/fs/btrfs/file.c >> +++ b/fs/btrfs/file.c >> @@ -1533,6 +1533,25 @@ lock_and_cleanup_extent_if_need(struct btrfs_in= ode *inode, struct page **pages, >> return ret; >> } >> =20 >> +/* >> + * Check if we can do nocow write into the range [@pos, @pos + @write= _bytes) >> + * >> + * This function will flush ordered extents in the range to ensure pr= oper >> + * nocow checks for (nowait =3D=3D false) case. >> + * >> + * Return >0 and update @write_bytes if we can do nocow write into th= e range. >> + * Return 0 if we can't do nocow write. >> + * Return -EAGAIN if we can't get the needed lock, or for (nowait =3D= =3D true) case, >> + * there are ordered extents need to be flushed. >> + * Return <0 for if other error happened. >> + * >> + * NOTE: For wait (nowait=3D=3Dfalse) calls, callers need to release = the drew write >> + * lock of inode->root->snapshot_lock if return value > 0. >> + * >> + * @pos: File offset of the range >> + * @write_bytes: The length of the range to check, also contains the = nocow >> + * writable length if we can do nocow write >> + */ >> static noinline int check_can_nocow(struct btrfs_inode *inode, loff_t= pos, >> size_t *write_bytes, bool nowait) >> { >> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c >> index 86f7aa377da9..48e16eae7278 100644 >> --- a/fs/btrfs/inode.c >> +++ b/fs/btrfs/inode.c >> @@ -6922,8 +6922,23 @@ static struct extent_map *btrfs_new_extent_dire= ct(struct inode *inode, >> } >> =20 >> /* >> - * returns 1 when the nocow is safe, < 1 on error, 0 if the >> - * block must be cow'd >> + * Check if we can write into [@offset, @offset + @len) of @inode. >> + * >> + * Return >0 and update @len if we can do nocow write into [@offset, = @offset + >> + * @len). >> + * Return 0 if we can't do nocow write. >> + * Return <0 if error happened. >> + * >> + * NOTE: This only checks the file extents, caller is responsible to = wait for >> + * any ordered extents. >> + * >> + * @offset: File offset >> + * @len: The length to write, will be updated to the nocow writable >> + * range >> + * >> + * @orig_start: (Optional) Return the original file offset of the fil= e extent >> + * @orig_len: (Optional) Return the original on-disk length of the fi= le extent >> + * @ram_bytes: (Optional) Return the ram_bytes of the file extent >> */ >> noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *l= en, >> u64 *orig_start, u64 *orig_block_len, >> >=20 --FdjruJuEVTaVjQKVdM3evktHpnsyDGxCE-- --FZzGN4dq0CguPJqQd3RNzM5rC9j7Pvzfn Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAl7rV1YACgkQwj2R86El /qh8egf+LTypcTFImqqK+sAeYZy0X/DIpGaBvmOcFYwyqnhNmCTKrE+l8Qq7vzcO eyIRxsxW+CPeD1BsVEH8IfNo4VdH8RmQ096Q1aaTagnS56SUdENYCdDlywj494+c iUbXJE1KUIVKyOT6DGXUEc5ymoAxcWM8mddnJloSh5KvtimIGj86T8kJH/5xINr6 uWzvhP6J4PV5AjlEaFWBmnxrCyM6toEY67eq1FzJwXhaLYGhGJooZvCvfrRbfS1Y hCYEmPRyB1+cS6b0n7nv0CqdY/Ngz3Rq5sKsCybqyGTTQ/vQV2xk30yAa0jTvpJV 27Q0izsgQhfBlFLwnPXNKtu/tLUjBw== =aoKx -----END PGP SIGNATURE----- --FZzGN4dq0CguPJqQd3RNzM5rC9j7Pvzfn--