From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754170AbdKHDHF (ORCPT ); Tue, 7 Nov 2017 22:07:05 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:9975 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754076AbdKHDHD (ORCPT ); Tue, 7 Nov 2017 22:07:03 -0500 Subject: Re: [PATCH v2] f2fs: add bug_on when f2fs_gc even fails to get one victim To: Chao Yu , Jaegeuk Kim CC: , , , , , , References: <1507729864-118702-1-git-send-email-yunlong.song@huawei.com> <1507901500-162168-1-git-send-email-yunlong.song@huawei.com> <20171103034402.GC11335@jaegeuk-macbookpro.roam.corp.google.com> <3b26badb-c34e-3c2d-74a2-26ecef1f64ff@huawei.com> <20171107023835.GG88544@jaegeuk-macbookpro.roam.corp.google.com> <20171107024058.GH88544@jaegeuk-macbookpro.roam.corp.google.com> <20171107032636.GB92599@jaegeuk-macbookpro.roam.corp.google.com> <7433d584-b1e0-76e9-a6e4-8da1218dd71d@huawei.com> From: Yunlong Song Message-ID: <19eec8fd-e941-770a-9477-6ad2d266d475@huawei.com> Date: Wed, 8 Nov 2017 11:06:29 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.111.220.140] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020205.5A0274CD.0042,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 20c7a0107845dfff9443a1dc0a088d9f Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org So we should use f2fs_bug_on(sbi, !total_freed && !sync && gc_type == FG_GC); On 2017/11/7 14:56, Chao Yu wrote: > On 2017/11/7 12:01, Yunlong Song wrote: >> Sorry, misunderstanding, because I think when sync == true, FG_GC does not >> check has_not_enough_free_secs, so maybe it does not have to do any gc >> at all. >> For example, if there are 100 segments for f2fs, and 20 segments are full or >> valid blocks over fggc_threshold, then it is correct to fail in get victim. >> >> >> On 2017/11/7 11:26, Jaegeuk Kim wrote: >>> On 11/07, Yunlong Song wrote: >>>> Because I find that some out-of-free problem is caused by the failure >>>> of get victim target. For example, chao has pointed out that he has >>>> found out a bug when adding this bug_on last week. >>> That's NOT what I asked. Why not checking FG_GC all the time like this? >>> >>> f2fs_bug_on(sbi, !total_freed && gc_type == FG_GC); > ioctl(F2FS_IOC_GARBAGE_COLLECT, &1) will simply trigger this bug_on, so we > have to check the conditon only when we run out-of-free-space? > > Thanks, > >>>> On 2017/11/7 10:40, Jaegeuk Kim wrote: >>>>> On 11/06, Jaegeuk Kim wrote: >>>>>> On 11/06, Yunlong Song wrote: >>>>>>> Agree. >>>>>>> >>>>>>> On 2017/11/3 11:44, Jaegeuk Kim wrote: >>>>>>>> On 10/13, Yunlong Song wrote: >>>>>>>>> This can help us to debug on some corner case. >>>>>>>>> >>>>>>>>> Signed-off-by: Yunlong Song >>>>>>>>> Signed-off-by: Chao Yu >>>>>>>>> --- >>>>>>>>> fs/f2fs/gc.c | 6 +++++- >>>>>>>>> 1 file changed, 5 insertions(+), 1 deletion(-) >>>>>>>>> >>>>>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >>>>>>>>> index 197ebf4..2b03202 100644 >>>>>>>>> --- a/fs/f2fs/gc.c >>>>>>>>> +++ b/fs/f2fs/gc.c >>>>>>>>> @@ -986,6 +986,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, >>>>>>>>> .ilist = LIST_HEAD_INIT(gc_list.ilist), >>>>>>>>> .iroot = RADIX_TREE_INIT(GFP_NOFS), >>>>>>>>> }; >>>>>>>>> + bool need_fggc = false; >>>>>>>>> trace_f2fs_gc_begin(sbi->sb, sync, background, >>>>>>>>> get_pages(sbi, F2FS_DIRTY_NODES), >>>>>>>>> @@ -1018,8 +1019,10 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, >>>>>>>>> if (ret) >>>>>>>>> goto stop; >>>>>>>>> } >>>>>>>>> - if (has_not_enough_free_secs(sbi, 0, 0)) >>>>>>>>> + if (has_not_enough_free_secs(sbi, 0, 0)) { >>>>>>>>> gc_type = FG_GC; >>>>>>>>> + need_fggc = true; >>>>>>>>> + } >>>>>>>>> } >>>>>>>>> /* f2fs_balance_fs doesn't need to do BG_GC in critical path. */ >>>>>>>>> @@ -1028,6 +1031,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, >>>>>>>>> goto stop; >>>>>>>>> } >>>>>>>>> if (!__get_victim(sbi, &segno, gc_type)) { >>>>>>>>> + f2fs_bug_on(sbi, !total_freed && need_fggc); >>>>>>>> Just like this? >>>>>>> That's OK. >>>>>> I'm not quite sure whether this is really a bug_on case. >>>>>> Let me make it WARN_ON() for debugging purpose first. >>>>> BTW, why is this the special case where BG_GC detects FG_GC? >>>>> >>>>>> Thanks, >>>>>> >>>>>>>> f2fs_bug_on(sbi, !total_freed && !sync && gc_type == FG_GC); >>>>>>>> >>>>>>>>> ret = -ENODATA; >>>>>>>>> goto stop; >>>>>>>>> } >>>>>>>>> -- >>>>>>>>> 1.8.5.2 >>>>>>>> . >>>>>>>> >>>>>>> -- >>>>>>> Thanks, >>>>>>> Yunlong Song >>>>>>> >>>>> . >>>>> >>>> -- >>>> Thanks, >>>> Yunlong Song >>>> >>> . >>> > > . > -- Thanks, Yunlong Song