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,URIBL_BLOCKED,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 14353C3A59B for ; Fri, 30 Aug 2019 18:47:06 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E95E423428 for ; Fri, 30 Aug 2019 18:47:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E95E423428 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=driverdev-devel-bounces@linuxdriverproject.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 9C6C2265F6; Fri, 30 Aug 2019 18:47:05 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id syRC+3AKYZpw; Fri, 30 Aug 2019 18:47:02 +0000 (UTC) Received: from ash.osuosl.org (ash.osuosl.org [140.211.166.34]) by silver.osuosl.org (Postfix) with ESMTP id 86990265BC; Fri, 30 Aug 2019 18:47:02 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by ash.osuosl.org (Postfix) with ESMTP id 283791BF3F6 for ; Fri, 30 Aug 2019 18:47:01 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 2078789383 for ; Fri, 30 Aug 2019 18:47:01 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7hHDaV5gKfp2 for ; Fri, 30 Aug 2019 18:47:00 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from huawei.com (szxga08-in.huawei.com [45.249.212.255]) by hemlock.osuosl.org (Postfix) with ESMTPS id E88268830D for ; Fri, 30 Aug 2019 18:46:59 +0000 (UTC) Received: from DGGEMM404-HUB.china.huawei.com (unknown [172.30.72.55]) by Forcepoint Email with ESMTP id 6A8539DBA69EB7AA3A3A; Sat, 31 Aug 2019 02:46:56 +0800 (CST) Received: from dggeme762-chm.china.huawei.com (10.3.19.108) by DGGEMM404-HUB.china.huawei.com (10.3.20.212) with Microsoft SMTP Server (TLS) id 14.3.439.0; Sat, 31 Aug 2019 02:46:55 +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; Sat, 31 Aug 2019 02:46:54 +0800 Date: Sat, 31 Aug 2019 02:46:06 +0800 From: Gao Xiang To: Christoph Hellwig Subject: Re: [PATCH v6 05/24] erofs: add inode operations Message-ID: <20190830184606.GA175612@architecture4> References: <20190802125347.166018-1-gaoxiang25@huawei.com> <20190802125347.166018-6-gaoxiang25@huawei.com> <20190829102426.GE20598@infradead.org> <20190829115922.GG64893@architecture4> <20190830164205.GD29603@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190830164205.GD29603@infradead.org> User-Agent: Mutt/1.9.4 (2018-02-28) X-Originating-IP: [10.140.130.215] X-ClientProxiedBy: dggeme708-chm.china.huawei.com (10.1.199.104) To dggeme762-chm.china.huawei.com (10.3.19.108) X-CFilter-Loop: Reflected X-BeenThere: driverdev-devel@linuxdriverproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Driver Project Developer List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devel@driverdev.osuosl.org, Stephen Rothwell , linux-erofs@lists.ozlabs.org, Chao Yu , Theodore Ts'o , "Darrick J . Wong" , Pavel Machek , Jan Kara , Amir Goldstein , Dave Chinner , David Sterba , Li Guifu , LKML , Miao Xie , Alexander Viro , Greg Kroah-Hartman , linux-fsdevel@vger.kernel.org, Jaegeuk Kim , Andrew Morton , Linus Torvalds , Fang Wei Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" Hi Christoph, On Fri, Aug 30, 2019 at 09:42:05AM -0700, Christoph Hellwig wrote: > On Thu, Aug 29, 2019 at 07:59:22PM +0800, Gao Xiang wrote: > > On Thu, Aug 29, 2019 at 03:24:26AM -0700, Christoph Hellwig wrote: > > > > [] > > > > > > > > > + > > > > + /* fill last page if inline data is available */ > > > > + err = fill_inline_data(inode, data, ofs); > > > > > > Well, I think you should move the is_inode_flat_inline and > > > (S_ISLNK(inode->i_mode) && inode->i_size < PAGE_SIZE) checks from that > > > helper here, as otherwise you make everyone wonder why you'd always > > > fill out the inline data. > > > > Currently, fill_inline_data() only fills for fast symlink, > > later we can fill any tail-end block (such as dir block) > > for our requirements. > > So change it when that later changes actually come in. And even then > having the checks outside the function is a lot more obvious. Okay. > > > And I think that is minor. > > The problem is that each of these issues might appear minor on their > own. But combined a lot of the coding style choices lead to code that > is more suitable an obsfucated code contest than the Linux kernel as > trying to understand even just a few places requires jumping through > tons of helpers with misleading names and spread over various files. > > > The consideration is simply because iget_locked performs better > > than iget5_locked. > > In what benchmark do the differences show up? In a word, no benchmark here, just because "unsigned long on 32-bit platforms is 4 bytes." but erofs nid is a 64-bit number. iget_locked will do find_inode_fast (no callback at all) rather than iget5_locked --> find_inode (test callback) -> inode_insert5(set callback) for each new inode. For most 64-bit platforms, iget_locked is enough, 32-bit platforms become rare... Thanks, Gao Xiang _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel