From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from szxga01-in.huawei.com ([45.249.212.187]:10747 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752379AbdHBJEO (ORCPT ); Wed, 2 Aug 2017 05:04:14 -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> <7e8346ed-8484-2ab9-85a1-03d232b16865@huawei.com> <3cbec840-a4ee-7d93-6b02-8f8f1483b7f6@huawei.com> From: Yunlong Song Message-ID: <4983e1e3-2dea-89c0-8c48-688691e3a0cd@huawei.com> Date: Wed, 2 Aug 2017 17:00:13 +0800 MIME-Version: 1.0 In-Reply-To: <3cbec840-a4ee-7d93-6b02-8f8f1483b7f6@huawei.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Agree, it's safe to bug_on or readonly to protect data. This patch is fine. On 2017/8/2 16:47, Chao Yu wrote: > Hi Yunlong, > > On 2017/8/2 16:02, Yunlong Song wrote: >> 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? > Actually, if that happens, I think both original and mirror bitmap datas are not > trustable, it's harmful to continue to trigger write IOs based on those bitmap > datas. So IMO, it would be better to trigger bug_on. > > At least, if only warning is showed, we'd better to turn f2fs to readonly and > fail current write IO. > > Thanks, > >> 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