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 7A1F2C3A5A6 for ; Fri, 30 Aug 2019 16:49:30 +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 58CED20820 for ; Fri, 30 Aug 2019 16:49:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 58CED20820 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 46B2926509; Fri, 30 Aug 2019 16:49:30 +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 Mx8gTtIwBmS6; Fri, 30 Aug 2019 16:49:26 +0000 (UTC) Received: from ash.osuosl.org (ash.osuosl.org [140.211.166.34]) by silver.osuosl.org (Postfix) with ESMTP id D6F7F264CC; Fri, 30 Aug 2019 16:49:26 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by ash.osuosl.org (Postfix) with ESMTP id 923541BF844 for ; Fri, 30 Aug 2019 16:49:25 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 8E16926424 for ; Fri, 30 Aug 2019 16:49:25 +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 zw-A7AaDxSdD for ; Fri, 30 Aug 2019 16:49:23 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from huawei.com (szxga01-in.huawei.com [45.249.212.187]) by silver.osuosl.org (Postfix) with ESMTPS id 5A8AC263DC for ; Fri, 30 Aug 2019 16:49:23 +0000 (UTC) Received: from DGGEMM404-HUB.china.huawei.com (unknown [172.30.72.53]) by Forcepoint Email with ESMTP id 6662DE36B8648C21C1E2; Sat, 31 Aug 2019 00:49:16 +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 00:49:15 +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 00:49:15 +0800 Date: Sat, 31 Aug 2019 00:48:27 +0800 From: Gao Xiang To: Christoph Hellwig Subject: Re: [PATCH v3 7/7] erofs: redundant assignment in __erofs_get_meta_page() Message-ID: <20190830164827.GA107220@architecture4> References: <20190830032006.GA20217@architecture4> <20190830033643.51019-1-gaoxiang25@huawei.com> <20190830033643.51019-7-gaoxiang25@huawei.com> <20190830162812.GA10694@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190830162812.GA10694@infradead.org> User-Agent: Mutt/1.9.4 (2018-02-28) X-Originating-IP: [10.140.130.215] X-ClientProxiedBy: dggeme705-chm.china.huawei.com (10.1.199.101) 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, Chao Yu , Greg Kroah-Hartman , Miao Xie , Chao Yu , LKML , weidu.du@huawei.com, Fang Wei , Joe Perches , linux-erofs@lists.ozlabs.org, Dan Carpenter 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 09:28:12AM -0700, Christoph Hellwig wrote: > > - err = bio_add_page(bio, page, PAGE_SIZE, 0); > > - if (err != PAGE_SIZE) { > > + if (bio_add_page(bio, page, PAGE_SIZE, 0) != PAGE_SIZE) { > > err = -EFAULT; > > goto err_out; > > } > > This patch looks like an improvement. But looking at that whole > area just makes me cringe. OK, I agree with you, I will improve it or just kill them all with new iomap approach after it supports tail-end packing inline. > > Why is there __erofs_get_meta_page with the two weird booleans instead > of a single erofs_get_meta_page that gets and gfp_t for additional > flags and an unsigned int for additional bio op flags. I agree with you. Thanks for your suggestion. > > Why do need ioprio support to start with? Seeing that in a new > fs look kinda odd. Do you have benchmarks that show the difference? I don't have some benchmark for all of these, can I just set REQ_PRIO for all metadata? is that reasonable? Could you kindly give some suggestion on this? > > That function then calls erofs_grab_bio, which tries to handle a > bio_alloc failure, except that the function will not actually fail > due the mempool backing it. It also seems like and awfully > huge function to inline. OK, I will simplify it. Thanks for your suggestion. > > Why is there __submit_bio which really just obsfucates what is > going on? Also why is __submit_bio using bio_set_op_attrs instead > of opencode it as the comment right next to it asks you to? Originally, mainly due to backport consideration since some of our smartphones use 3.x kernel as well... > > Also I really don't understand why you can't just use read_cache_page > or even read_cache_page_gfp instead of __erofs_get_meta_page. > That function is a whole lot of duplication of functionality shared > by a lot of other file systems. OK, I have to admit, that code was originally just copied from f2fs with some modification (maybe it's not a good example for us). Thanks, Gao Xiang _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel