From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:40294 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751829AbdFNO7Z (ORCPT ); Wed, 14 Jun 2017 10:59:25 -0400 Subject: Re: [f2fs-dev] [PATCH] f2fs: fix ref of discard command To: Jaegeuk Kim , Chao Yu Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net References: <20170612030449.79290-1-jaegeuk@kernel.org> <54b5aaad-1674-8d76-c489-d5eee6ef7f26@huawei.com> <20170614142648.GA74571@jaegeuk-macbookpro.roam.corp.google.com> From: Chao Yu Message-ID: <9c37cfd8-3fc1-43b6-91d8-9f9dbf15a4d7@kernel.org> Date: Wed, 14 Jun 2017 22:58:54 +0800 MIME-Version: 1.0 In-Reply-To: <20170614142648.GA74571@jaegeuk-macbookpro.roam.corp.google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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? 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 >