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=-3.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_HIGH,UNPARSEABLE_RELAY,USER_AGENT_NEOMUTT 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 E89EAC4646D for ; Mon, 13 Aug 2018 11:04:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F4B221767 for ; Mon, 13 Aug 2018 11:04:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="xWl6QZ08" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F4B221767 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729218AbeHMNqS (ORCPT ); Mon, 13 Aug 2018 09:46:18 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:54554 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728402AbeHMNqR (ORCPT ); Mon, 13 Aug 2018 09:46:17 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w7DAxGKD029115; Mon, 13 Aug 2018 11:04:17 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=GmdtXyFP4FDw/SQjYO6enCAV8uVXorjxrsBh9Vzv+Dk=; b=xWl6QZ08Suh0vn8cWqUbs0bzVysUrRHUt/YeGWDWLwCQbbtrI1ZYWeSzRk8atixS+xH3 xWG0lKOAC8N4Wjx4XqBu16KT1QeJ0CDYyXLIZvl48XnvNRFCt47i2lYoZyv5RjDJVySN pnxzsYGJfe8EDMoG3OcdfkykitnKhe2NDERhWzyhTlSimzZqiIJx6o2o4pVqVBezSztu hEOJpvngx5cAnBaDaXMkAIWX251rJKg7BB4TRjLrtEW6jT8gOdeQStGRgzvRs9tr/41k N5q07LfoIJnPeQGRUfftLBlxz2o7zhJ/VWhNzkoWap9f19rk1cUfJEEghX5C1DqSWfLF cQ== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp2120.oracle.com with ESMTP id 2ksrepumj6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 13 Aug 2018 11:04:16 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w7DB4Gjb017221 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 13 Aug 2018 11:04:16 GMT Received: from abhmp0005.oracle.com (abhmp0005.oracle.com [141.146.116.11]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w7DB4ECH019441; Mon, 13 Aug 2018 11:04:14 GMT Received: from mwanda (/197.232.248.111) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 13 Aug 2018 04:04:14 -0700 Date: Mon, 13 Aug 2018 14:04:06 +0300 From: Dan Carpenter To: Chao Yu Cc: gregkh@linuxfoundation.org, devel@driverdev.osuosl.org, Gao Xiang , Chao Yu , linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/8] staging: erofs: separate erofs_get_meta_page Message-ID: <20180813110405.3qoburir3ds5ux33@mwanda> References: <20180812140150.13397-1-chao@kernel.org> <20180812140150.13397-3-chao@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180812140150.13397-3-chao@kernel.org> User-Agent: NeoMutt/20170609 (1.8.3) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8983 signatures=668707 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1808130120 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 12, 2018 at 10:01:44PM +0800, Chao Yu wrote: > --- a/drivers/staging/erofs/data.c > +++ b/drivers/staging/erofs/data.c > @@ -39,31 +39,44 @@ static inline void read_endio(struct bio *bio) > } > > /* prio -- true is used for dir */ > -struct page *erofs_get_meta_page(struct super_block *sb, > - erofs_blk_t blkaddr, bool prio) > +struct page *__erofs_get_meta_page(struct super_block *sb, > + erofs_blk_t blkaddr, bool prio, bool nofail) > { > - struct inode *bd_inode = sb->s_bdev->bd_inode; > - struct address_space *mapping = bd_inode->i_mapping; > + struct inode *const bd_inode = sb->s_bdev->bd_inode; > + struct address_space *const mapping = bd_inode->i_mapping; > + /* prefer retrying in the allocator to blindly looping below */ > + const gfp_t gfp = mapping_gfp_constraint(mapping, ~__GFP_FS) | > + (nofail ? __GFP_NOFAIL : 0); > + unsigned int io_retries = nofail ? EROFS_IO_MAX_RETRIES_NOFAIL : 0; > struct page *page; > > repeat: > - page = find_or_create_page(mapping, blkaddr, > - /* > - * Prefer looping in the allocator rather than here, > - * at least that code knows what it's doing. > - */ > - mapping_gfp_constraint(mapping, ~__GFP_FS) | __GFP_NOFAIL); > - > - BUG_ON(!page || !PageLocked(page)); > + page = find_or_create_page(mapping, blkaddr, gfp); > + if (unlikely(page == NULL)) { > + DBG_BUGON(nofail); > + return ERR_PTR(-ENOMEM); > + } > + DBG_BUGON(!PageLocked(page)); > > if (!PageUptodate(page)) { > struct bio *bio; > int err; > > - bio = erofs_grab_bio(sb, blkaddr, 1, read_endio, true); > + bio = erofs_grab_bio(sb, blkaddr, 1, read_endio, nofail); > + if (unlikely(bio == NULL)) { > + DBG_BUGON(nofail); > + err = -ENOMEM; > +err_out: > + unlock_page(page); > + put_page(page); > + return ERR_PTR(err); Put this err_out stuff at the bottom of the function so that we don't have to do backward hops to get to it. > + } > > err = bio_add_page(bio, page, PAGE_SIZE, 0); > - BUG_ON(err != PAGE_SIZE); > + if (unlikely(err != PAGE_SIZE)) { > + err = -EFAULT; > + goto err_out; ^^^^^^^^^^^^ Like this. Generally avoid backwards hops if you can. > + } > > __submit_bio(bio, REQ_OP_READ, > REQ_META | (prio ? REQ_PRIO : 0)); > @@ -72,6 +85,7 @@ struct page *erofs_get_meta_page(struct super_block *sb, > > /* the page has been truncated by others? */ > if (unlikely(page->mapping != mapping)) { > +unlock_repeat: The question mark in the "truncated by others?" is a little concerning. It's slightly weird that we don't check "io_retries" on this path. > unlock_page(page); > put_page(page); > goto repeat; > @@ -79,10 +93,12 @@ struct page *erofs_get_meta_page(struct super_block *sb, > > /* more likely a read error */ > if (unlikely(!PageUptodate(page))) { > - unlock_page(page); > - put_page(page); > - > - page = ERR_PTR(-EIO); > + if (io_retries) { > + --io_retries; > + goto unlock_repeat; > + } > + err = -EIO; > + goto err_out; regards, dan carpenter