From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753129AbdFNPUT (ORCPT ); Wed, 14 Jun 2017 11:20:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:43548 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752049AbdFNPUQ (ORCPT ); Wed, 14 Jun 2017 11:20:16 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E7C82239B0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=jaegeuk@kernel.org Date: Wed, 14 Jun 2017 08:20:07 -0700 From: Jaegeuk Kim To: Chao Yu Cc: Chao Yu , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: fix ref of discard command Message-ID: <20170614152007.GD74571@jaegeuk-macbookpro.roam.corp.google.com> References: <20170612030449.79290-1-jaegeuk@kernel.org> <54b5aaad-1674-8d76-c489-d5eee6ef7f26@huawei.com> <20170614142648.GA74571@jaegeuk-macbookpro.roam.corp.google.com> <9c37cfd8-3fc1-43b6-91d8-9f9dbf15a4d7@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9c37cfd8-3fc1-43b6-91d8-9f9dbf15a4d7@kernel.org> User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/14, Chao Yu wrote: > On 2017/6/14 22:26, Jaegeuk Kim wrote: > > On 06/12, Chao Yu wrote: > >> Hi Jaegeuk, > >> > >> On 2017/6/12 11:04, Jaegeuk Kim wrote: > >>> This patch resolves kernel panic for xfstests/081, caused by recent f2fs_bug_on > >>> > >>> f2fs: add f2fs_bug_on in __remove_discard_cmd > >>> > >>> Signed-off-by: Jaegeuk Kim > >>> --- > >>> fs/f2fs/segment.c | 2 ++ > >>> 1 file changed, 2 insertions(+) > >>> > >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > >>> index 86a0c1095939..a6d77388a806 100644 > >>> --- a/fs/f2fs/segment.c > >>> +++ b/fs/f2fs/segment.c > >>> @@ -1025,6 +1025,8 @@ static void __wait_discard_cmd(struct f2fs_sb_info *sbi, bool wait_cond) > >>> list_for_each_entry_safe(dc, tmp, wait_list, list) { > >>> if (!wait_cond || (dc->state == D_DONE && !dc->ref)) { > >>> wait_for_completion_io(&dc->wait); > >>> + if (dc->state == D_DONE && dc->ref) > >>> + dc->ref--; > >> > >> Should set dc->ref to 0 to avoid panic once we add other referrers? > > > > Sorry, could you please explain this in more detail? > > Oh, I just assume later we may add another referrer for some reason > which will make dc->ref = 2, so dc->ref-- is not enough to avoid the > bug_on in __remove_discard_cmd. I think reseting dc->ref is more safe > here, how do you think? Well, for now, it makes more sense to do like this when considering ref flow, IIUC. What will make dc->ref = 2 later? Even in that case, why not making zero by adding dc->ref-- appropriately? Thanks, > > Thanks, > > > > > Thanks, > > > >> > >> Thanks, > >> > >>> __remove_discard_cmd(sbi, dc); > >>> } else { > >>> dc->ref++; > >>> > > > > ------------------------------------------------------------------------------ > > Check out the vibrant tech community on one of the world's most > > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > _______________________________________________ > > Linux-f2fs-devel mailing list > > Linux-f2fs-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > >