From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754972AbdKGG5z (ORCPT ); Tue, 7 Nov 2017 01:57:55 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:10017 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754947AbdKGG5x (ORCPT ); Tue, 7 Nov 2017 01:57:53 -0500 Subject: Re: [PATCH v2] f2fs: add bug_on when f2fs_gc even fails to get one victim To: Yunlong Song , 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: Chao Yu Message-ID: Date: Tue, 7 Nov 2017 14:56:26 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <7433d584-b1e0-76e9-a6e4-8da1218dd71d@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020204.5A015958.0061,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: 919335ccba5f1f7aaf58c8efa76eea8f Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >>> >> . >> >