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=-14.1 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 4E5A8C433DF for ; Tue, 18 Aug 2020 08:29:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 356BB206B5 for ; Tue, 18 Aug 2020 08:29:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726476AbgHRI3M (ORCPT ); Tue, 18 Aug 2020 04:29:12 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:9833 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726043AbgHRI3L (ORCPT ); Tue, 18 Aug 2020 04:29:11 -0400 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id E2CAB93B21F94BEC3230; Tue, 18 Aug 2020 16:29:08 +0800 (CST) Received: from [10.136.114.67] (10.136.114.67) by smtp.huawei.com (10.3.19.211) with Microsoft SMTP Server (TLS) id 14.3.487.0; Tue, 18 Aug 2020 16:29:06 +0800 Subject: Re: [PATCH] f2fs: fix indefinite loop scanning for free nid To: Sahitya Tummala , Jaegeuk Kim , CC: References: <1597392335-4998-1-git-send-email-stummala@codeaurora.org> From: Chao Yu Message-ID: Date: Tue, 18 Aug 2020 16:29:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1597392335-4998-1-git-send-email-stummala@codeaurora.org> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.136.114.67] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/8/14 16:05, Sahitya Tummala wrote: > If the sbi->ckpt->next_free_nid is not NAT block aligned and if there > are free nids in that NAT block between the start of the block and > next_free_nid, then those free nids will not be scanned in scan_nat_page(). > This results into mismatch between nm_i->available_nids and the sum of > nm_i->free_nid_count of all NAT blocks scanned. And nm_i->available_nids > will always be greater than the sum of free nids in all the blocks. > Under this condition, if we use all the currently scanned free nids, > then it will loop forever in f2fs_alloc_nid() as nm_i->available_nids > is still not zero but nm_i->free_nid_count of that partially scanned > NAT block is zero. > > Fix this to align the nm_i->next_scan_nid to the first nid of the > corresponding NAT block. > > Signed-off-by: Sahitya Tummala > --- > fs/f2fs/node.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > index 9bbaa26..d615e59 100644 > --- a/fs/f2fs/node.c > +++ b/fs/f2fs/node.c > @@ -2402,6 +2402,8 @@ static int __f2fs_build_free_nids(struct f2fs_sb_info *sbi, > if (IS_ERR(page)) { > ret = PTR_ERR(page); > } else { > + if (nid % NAT_ENTRY_PER_BLOCK) > + nid = NAT_BLOCK_OFFSET(nid) * NAT_ENTRY_PER_BLOCK; How about moving this logic to the beginning of __f2fs_build_free_nids(), after nid reset? BTW, it looks we can add unlikely in this judgment condition? Thanks, > ret = scan_nat_page(sbi, page, nid); > f2fs_put_page(page, 1); > } >