From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751603AbdKGEEb (ORCPT ); Mon, 6 Nov 2017 23:04:31 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:55713 "EHLO huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751307AbdKGEEa (ORCPT ); Mon, 6 Nov 2017 23:04:30 -0500 Subject: Re: [PATCH v2] f2fs: add bug_on when f2fs_gc even fails to get one victim To: 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> From: Yunlong Song Message-ID: <7433d584-b1e0-76e9-a6e4-8da1218dd71d@huawei.com> Date: Tue, 7 Nov 2017 12:01:58 +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: <20171107032636.GB92599@jaegeuk-macbookpro.roam.corp.google.com> 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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); > >> 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