Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751837AbdHBIDM (ORCPT ); Wed, 2 Aug 2017 04:03:12 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:10746 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750725AbdHBIDK (ORCPT ); Wed, 2 Aug 2017 04:03:10 -0400 Subject: Re: [PATCH] f2fs: update cur_valid_map_mir together with cur_valid_map To: Chao Yu , Yunlong Song , Chao Yu CC: jaegeuk , miaoxie , "bintian.wang" , linux-fsdevel , linux-f2fs-devel , linux-kernel References: <1501574206-150946-1-git-send-email-yunlong.song@huawei.com> <8be82ea4-db80-8f87-9029-e63d2926f7d1@huawei.com> From: Yunlong Song Message-ID: <7e8346ed-8484-2ab9-85a1-03d232b16865@huawei.com> Date: Wed, 2 Aug 2017 16:02:35 +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: <8be82ea4-db80-8f87-9029-e63d2926f7d1@huawei.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 X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020205.59818737.0077,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: 9022cc6ee37c15601081b26f8411eca2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6603 Lines: 168 Hi Chao, For the memory overflow or cache bit-transition case, when CHECK_FS is on, should f2fs enter panic or just provide WARNing information? I prefer WARNing, because it is not f2fs's fault, f2fs does not need to pay for it, why not use WARN_ON instead? On 2017/8/2 9:34, Chao Yu wrote: > Hi Yunlong, > > On 2017/8/2 0:59, Yunlong Song wrote: >> Hi Chao, >> I think there is no need to test mirror bitmap when original bitmap's check >> get passed, it is an instruction waste for "test". By the way, previous patch >> uses WARN to skip trigger panic when the memory is flipped, I think it is proper >> to not trigger panic in this situation, because it is not code bug at all in >> such case. > Original idea is trying to use bitmap mirror to detect bitmap corruption caused > by memory overflow or bit-transition of cache. > > So if we encounter inconsistency in between original bitmap and mirror bitmap, > there may be memory overflow or cache bit-transition, we need to detect that; > another case is that both bitmap is consistent, but we are trying to reuse valid > block address or free invalid block address, indeed that is a bug. > > Below modification can cover above two cases, which make original idea of > introducing mirror bitmap check working correctly. > > Thanks, > >> On 08/01/2017 23:44, Chao Yu wrote: >> >> Hi Yunlong, >> >> How about checking consistence in between original and mirror bitmap all >> the time as below? >> >> --- >> fs/f2fs/segment.c | 41 +++++++++++++++++++++++++++-------------- >> 1 file changed, 27 insertions(+), 14 deletions(-) >> >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >> index a26c24dae70c..f32a19cf486a 100644 >> --- a/fs/f2fs/segment.c >> +++ b/fs/f2fs/segment.c >> @@ -1510,6 +1510,7 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, >> block_t blkaddr, int del) >> struct seg_entry *se; >> unsigned int segno, offset; >> long int new_vblocks; >> + bool exist, mir_exist; >> >> segno = GET_SEGNO(sbi, blkaddr); >> >> @@ -1526,17 +1527,23 @@ static void update_sit_entry(struct f2fs_sb_info >> *sbi, block_t blkaddr, int del) >> >> /* Update valid block bitmap */ >> if (del > 0) { >> - if (f2fs_test_and_set_bit(offset, se->cur_valid_map)) { >> + exist = f2fs_test_and_set_bit(offset, se->cur_valid_map); >> #ifdef CONFIG_F2FS_CHECK_FS >> - if (f2fs_test_and_set_bit(offset, >> - se->cur_valid_map_mir)) >> - f2fs_bug_on(sbi, 1); >> - else >> - WARN_ON(1); >> -#else >> + mir_exist = f2fs_test_and_set_bit(offset, >> + se->cur_valid_map_mir); >> + if (exist != mir_exist) { >> + f2fs_msg(sbi->sb, KERN_ERR, "Inconsistent error " >> + "when setting bitmap, blk:%u, old bit:%d", >> + blkaddr, exist); >> f2fs_bug_on(sbi, 1); >> + } >> #endif >> + if (exist) { >> + f2fs_msg(sbi->sb, KERN_ERR, >> + "Bitmap was set, blk:%u", blkaddr); >> + f2fs_bug_on(sbi, 1); >> } >> + >> if (f2fs_discard_en(sbi) && >> !f2fs_test_and_set_bit(offset, se->discard_map)) >> sbi->discard_blks--; >> @@ -1547,17 +1554,23 @@ static void update_sit_entry(struct f2fs_sb_info >> *sbi, block_t blkaddr, int del) >> se->ckpt_valid_blocks++; >> } >> } else { >> - if (!f2fs_test_and_clear_bit(offset, se->cur_valid_map)) { >> + exist = f2fs_test_and_clear_bit(offset, se->cur_valid_map); >> #ifdef CONFIG_F2FS_CHECK_FS >> - if (!f2fs_test_and_clear_bit(offset, >> - se->cur_valid_map_mir)) >> - f2fs_bug_on(sbi, 1); >> - else >> - WARN_ON(1); >> -#else >> + mir_exist = f2fs_test_and_clear_bit(offset, >> + se->cur_valid_map_mir); >> + if (exist != mir_exist) { >> + f2fs_msg(sbi->sb, KERN_ERR, "Inconsistent error " >> + "when clearing bitmap, blk:%u, old bit:%d", >> + blkaddr, exist); >> f2fs_bug_on(sbi, 1); >> + } >> #endif >> + if (!exist) { >> + f2fs_msg(sbi->sb, KERN_ERR, >> + "Bitmap was cleared, blk:%u", blkaddr); >> + f2fs_bug_on(sbi, 1); >> } >> + >> if (f2fs_discard_en(sbi) && >> f2fs_test_and_clear_bit(offset, se->discard_map)) >> sbi->discard_blks++; >> -- >> 2.13.0.90.g1eb437020 >> >> On 2017/8/1 15:56, Yunlong Song wrote: >> > When cur_valid_map passes the f2fs_test_and_set(,clear)_bit test, >> > cur_valid_map_mir update is skipped unlikely, so fix it. >> > >> > Signed-off-by: Yunlong Song >> > --- >> > fs/f2fs/segment.c | 8 ++++++++ >> > 1 file changed, 8 insertions(+) >> > >> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >> > index 151968e..6f7731a 100644 >> > --- a/fs/f2fs/segment.c >> > +++ b/fs/f2fs/segment.c >> > @@ -1535,6 +1535,10 @@ static void update_sit_entry(struct f2fs_sb_info >> *sbi, block_t blkaddr, int del) >> > f2fs_bug_on(sbi, 1); >> > #endif >> > } >> > +#ifdef CONFIG_F2FS_CHECK_FS >> > + else >> > + f2fs_set_bit(offset, se->cur_valid_map_mir); >> > +#endif >> > if (f2fs_discard_en(sbi) && >> > !f2fs_test_and_set_bit(offset, se->discard_map)) >> > sbi->discard_blks--; >> > @@ -1556,6 +1560,10 @@ static void update_sit_entry(struct f2fs_sb_info >> *sbi, block_t blkaddr, int del) >> > f2fs_bug_on(sbi, 1); >> > #endif >> > } >> > +#ifdef CONFIG_F2FS_CHECK_FS >> > + else >> > + f2fs_clear_bit(offset, se->cur_valid_map_mir); >> > +#endif >> > if (f2fs_discard_en(sbi) && >> > f2fs_test_and_clear_bit(offset, se->discard_map)) >> > sbi->discard_blks++; >> > >> > > . > -- Thanks, Yunlong Song