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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 99195C2D0DB for ; Thu, 23 Jan 2020 11:15:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6679E206D4 for ; Thu, 23 Jan 2020 11:15:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726231AbgAWLPw (ORCPT ); Thu, 23 Jan 2020 06:15:52 -0500 Received: from mx2.suse.de ([195.135.220.15]:54290 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726026AbgAWLPv (ORCPT ); Thu, 23 Jan 2020 06:15:51 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 31D0EB260; Thu, 23 Jan 2020 11:15:50 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id E21241E0B01; Thu, 23 Jan 2020 12:15:43 +0100 (CET) Date: Thu, 23 Jan 2020 12:15:43 +0100 From: Jan Kara To: Vasily Averin Cc: linux-ext4@vger.kernel.org, Theodore Ts'o , Jan Kara Subject: Re: [PATCH 1/1] jbd2_seq_info_next should increase position index Message-ID: <20200123111543.GC5728@quack2.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu 23-01-20 12:05:10, Vasily Averin wrote: > if seq_file .next fuction does not change position index, > read after some lseek can generate unexpected output. > > Script below generates endless output > $ q=;while read -r r;do echo "$((++q)) $r";done > https://bugzilla.kernel.org/show_bug.cgi?id=206283 > Signed-off-by: Vasily Averin > --- > fs/jbd2/journal.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c > index 5e408ee..b3e2433 100644 > --- a/fs/jbd2/journal.c > +++ b/fs/jbd2/journal.c > @@ -982,6 +982,7 @@ static void *jbd2_seq_info_start(struct seq_file *seq, loff_t *pos) > > static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos) > { > + (*pos)++; > return NULL; > } > > -- > 1.8.3.1 > -- Jan Kara SUSE Labs, CR