linux-kernel - Re: [PATCH] f2fs: let fill_super handle roll-forward errors

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Date:   Wed, 16 Aug 2017 09:17:55 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>, <stable@...r.kernel.org>
Subject: Re: [PATCH] f2fs: let fill_super handle roll-forward errors

On 2017/8/16 0:42, Jaegeuk Kim wrote:
> On 08/15, Chao Yu wrote:
>> On 2017/8/15 11:22, Jaegeuk Kim wrote:
>>> On 08/15, Chao Yu wrote:
>>>> Hi Jaegeuk,
>>>>
>>>> On 2017/8/11 8:42, Jaegeuk Kim wrote:
>>>>> If we set CP_ERROR_FLAG in roll-forward error, f2fs is no longer to proceed
>>>>> any IOs due to f2fs_cp_error(). But, for example, if some stale data is involved
>>>>> on roll-forward process, we're able to get -ENOENT, getting fs stuck.
>>>>> If we get any error, let fill_super set SBI_NEED_FSCK and try to recover back
>>>>> to stable point.
>>>>
>>>> Before that, we have cleaned up all node/meta page cache, so we will get back to
>>>> last checkpoint status, means losing fsynced datas for ever.
>>>>
>>>> Would it be better to just leave message reminding user to mount with
>>>> disable_roll_forward or run fsck offline.
>>>
>>> We can't rely on user for this, since fsck cannot recover this, resulting in
>>
>> If fsck has no ability to recover this, it could tag superblock in somewhere,
>> then kernel could skip recovery. Comparing to fail recovery directly, it give
>> user another chance to rescuer his datas.
> 
> Huh, what do you mean? This patch let f2fs_fill_super set SBI_NEED_FSCK in
> superblock and skip roll-forward in second round.

Oh, just notice that additional checkpoint which sets SBI_NEED_FSCK won't
destroy warn node chain, so we have chance to run fsck and recover after another
mount. Sorry.

Reviewed-by: Chao Yu <yuchao0@...wei.com>

> 
>>
>> Thanks,
>>
>>> infinite mount failure. The only way is to disable roll-forward recovery, which
>>> is same as returning error here.
>>>
>>> Thanks,
>>>
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>> Cc: <stable@...r.kernel.org>
>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>>>> ---
>>>>>  fs/f2fs/recovery.c | 2 --
>>>>>  1 file changed, 2 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
>>>>> index a3d02613934a..f707d810c87d 100644
>>>>> --- a/fs/f2fs/recovery.c
>>>>> +++ b/fs/f2fs/recovery.c
>>>>> @@ -649,8 +649,6 @@ int recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)
>>>>>  	}
>>>>>  
>>>>>  	clear_sbi_flag(sbi, SBI_POR_DOING);
>>>>> -	if (err)
>>>>> -		set_ckpt_flags(sbi, CP_ERROR_FLAG);
>>>>>  	mutex_unlock(&sbi->cp_mutex);
>>>>>  
>>>>>  	/* let's drop all the directory inodes for clean checkpoint */
>>>>>
>>>
>>> .
>>>
> 
> .
>