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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,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 18910C4360C for ; Thu, 26 Sep 2019 21:46:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DF07722459 for ; Thu, 26 Sep 2019 21:46:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569534416; bh=YFSTeeZZg2BEdjJrQ0yOpq9LuFuTUYJSINpPZwsXoNA=; h=Date:From:To:Subject:References:In-Reply-To:List-ID:From; b=qXH56Ag/ZTjZrilz9iqkJ68P1GJz0T8mxknt8/Br6YKRUQuplTPYO9hYxV030X/K8 EOx3G3VtjrR6oNr2TAXAPzyct/eqin0M8colU892YtdRX717QWzgNbXaeYKOm4kULi Ec0s1H8aFj+E9C0XjuScBZ24l6oCrEk2UH2NHQmk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726166AbfIZVq4 (ORCPT ); Thu, 26 Sep 2019 17:46:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:35222 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725793AbfIZVqz (ORCPT ); Thu, 26 Sep 2019 17:46:55 -0400 Received: from localhost (unknown [104.132.0.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 87A8520835; Thu, 26 Sep 2019 21:46:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569534414; bh=YFSTeeZZg2BEdjJrQ0yOpq9LuFuTUYJSINpPZwsXoNA=; h=Date:From:To:Subject:References:In-Reply-To:From; b=HulqdxyFFzYLCuFdB6S8z4wjmKjtrInzlxyS0r7j/rI3lUQ/NKMufJxWyMb4I1Fe8 DQUy1gQBOQjsiQe+082e8TftblxkJ1A6v8FDtwqcgJZ0lmHuu+wnP+voM3dR+z2YWp /+Vcsje0As2K42GFUjvwCmLPw/nZDOAIctfJMo+c= Date: Thu, 26 Sep 2019 14:46:53 -0700 From: Jaegeuk Kim To: Chao Yu , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: fix to avoid data corruption by forbidding SSR overwrite Message-ID: <20190926214653.GA29685@jaegeuk-macbookpro.roam.corp.google.com> References: <20190816030334.81035-1-yuchao0@huawei.com> <20190926203755.GA142676@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190926203755.GA142676@gmail.com> User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/26, Eric Biggers wrote: > On Fri, Aug 16, 2019 at 11:03:34AM +0800, Chao Yu wrote: > > There is one case can cause data corruption. > > > > - write 4k to fileA > > - fsync fileA, 4k data is writebacked to lbaA > > - write 4k to fileA > > - kworker flushs 4k to lbaB; dnode contain lbaB didn't be persisted yet > > - write 4k to fileB > > - kworker flush 4k to lbaA due to SSR > > - SPOR -> dnode with lbaA will be recovered, however lbaA contains fileB's > > data > > > > One solution is tracking all fsynced file's block history, and disallow > > SSR overwrite on newly invalidated block on that file. > > > > However, during recovery, no matter the dnode is flushed or fsynced, all > > previous dnodes until last fsynced one in node chain can be recovered, > > that means we need to record all block change in flushed dnode, which > > will cause heavy cost, so let's just use simple fix by forbidding SSR > > overwrite directly. > > > > Signed-off-by: Chao Yu > > --- > > fs/f2fs/segment.c | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > index 9d9d9a050d59..69b3b553ee6b 100644 > > --- a/fs/f2fs/segment.c > > +++ b/fs/f2fs/segment.c > > @@ -2205,9 +2205,11 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del) > > if (!f2fs_test_and_set_bit(offset, se->discard_map)) > > sbi->discard_blks--; > > > > - /* don't overwrite by SSR to keep node chain */ > > - if (IS_NODESEG(se->type) && > > - !is_sbi_flag_set(sbi, SBI_CP_DISABLED)) { > > + /* > > + * SSR should never reuse block which is checkpointed > > + * or newly invalidated. > > + */ > > + if (!is_sbi_flag_set(sbi, SBI_CP_DISABLED)) { > > if (!f2fs_test_and_set_bit(offset, se->ckpt_valid_map)) > > se->ckpt_valid_blocks++; > > } > > -- > > FYI, this commit caused xfstests generic/064 to start failing: Yup, I was looking at this. > > $ kvm-xfstests -c f2fs generic/064 > ... > generic/064 3s ... [13:36:37][ 5.946293] run fstests generic/064 at 2019-09-26 13:36:37 > [13:36:41]- output mismatch (see /results/f2fs/results-default/generic/064.out.bad) > --- tests/generic/064.out 2019-09-18 04:53:46.000000000 -0700 > +++ /results/f2fs/results-default/generic/064.out.bad 2019-09-26 13:36:41.533018683 -0700 > @@ -1,2 +1,3 @@ > QA output created by 064 > Extent count after inserts is in range > +extents mismatched before = 1 after = 50 > ... > (Run 'diff -u /root/xfstests/tests/generic/064.out /results/f2fs/results-default/generic/064.out.bad' to see the entire diff) > Ran: generic/064 > Failures: generic/064 > Failed 1 of 1 tests