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=-2.2 required=3.0 tests=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 433A6C3A59E for ; Mon, 2 Sep 2019 13:56:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25FE6217F4 for ; Mon, 2 Sep 2019 13:56:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730289AbfIBN4O (ORCPT ); Mon, 2 Sep 2019 09:56:14 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:3551 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730207AbfIBN4O (ORCPT ); Mon, 2 Sep 2019 09:56:14 -0400 Received: from DGGEMM401-HUB.china.huawei.com (unknown [172.30.72.56]) by Forcepoint Email with ESMTP id 483E9D60EC475B9922D5; Mon, 2 Sep 2019 21:56:12 +0800 (CST) Received: from dggeme762-chm.china.huawei.com (10.3.19.108) by DGGEMM401-HUB.china.huawei.com (10.3.20.209) with Microsoft SMTP Server (TLS) id 14.3.439.0; Mon, 2 Sep 2019 21:56:11 +0800 Received: from architecture4 (10.140.130.215) by dggeme762-chm.china.huawei.com (10.3.19.108) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1591.10; Mon, 2 Sep 2019 21:56:11 +0800 Date: Mon, 2 Sep 2019 21:55:20 +0800 From: Gao Xiang To: CC: Gao Xiang , Christoph Hellwig , "Jan Kara" , Dave Chinner , LKML , Miao Xie , , Stephen Rothwell , "Darrick J . Wong" , Linus Torvalds , Amir Goldstein , Alexander Viro , Jaegeuk Kim , Theodore Ts'o , Pavel Machek , "Greg Kroah-Hartman" , , Andrew Morton , Subject: Re: [PATCH v6 05/24] erofs: add inode operations Message-ID: <20190902135519.GD2664@architecture4> References: <20190802125347.166018-1-gaoxiang25@huawei.com> <20190802125347.166018-6-gaoxiang25@huawei.com> <20190829102426.GE20598@infradead.org> <20190901093326.GA6267@hsiangkao-HP-ZHAN-66-Pro-G1> <20190902134329.GU2752@twin.jikos.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20190902134329.GU2752@twin.jikos.cz> User-Agent: Mutt/1.9.4 (2018-02-28) X-Originating-IP: [10.140.130.215] X-ClientProxiedBy: dggeme707-chm.china.huawei.com (10.1.199.103) To dggeme762-chm.china.huawei.com (10.3.19.108) X-CFilter-Loop: Reflected Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi David, On Mon, Sep 02, 2019 at 03:43:29PM +0200, David Sterba wrote: > On Sun, Sep 01, 2019 at 05:34:00PM +0800, Gao Xiang wrote: > > > > +static int read_inode(struct inode *inode, void *data) > > > > +{ > > > > + struct erofs_vnode *vi = EROFS_V(inode); > > > > + struct erofs_inode_v1 *v1 = data; > > > > + const unsigned int advise = le16_to_cpu(v1->i_advise); > > > > + erofs_blk_t nblks = 0; > > > > + > > > > + vi->datamode = __inode_data_mapping(advise); > > > > > > What is the deal with these magic underscores here and various > > > other similar helpers? > > > > Fixed in > > https://lore.kernel.org/linux-fsdevel/20190901055130.30572-17-hsiangkao@aol.com/ > > > > underscores means 'internal' in my thought, it seems somewhat > > some common practice of Linux kernel, or some recent discussions > > about it?... I didn't notice these discussions... > > I know about a few valid uses of the underscores: > > * pattern where the __underscored version does not do locking, while the other > does > * similarly for atomic and non-atomic version > * macro that needs to manipulate the argument name (like glue some > prefix, so the macro does not have underscores and is supposed to be > used instead of the function with underscores that needs the full name > of a variable/constant/.. > * underscore function takes a few more parameters to further tune the > behaviour, but most users are fine with the defaults and that is > provided as a function without underscores > * in case you have just one function of the kind, don't use the underscores > > I can lookup examples if you're interested or if the brief description > is not sufficient. The list covers what I've seen and used, but the list > may be incomplete. Thanks, I learn a lot from the above. [thumb] Thanks, Gao Xiang