linux-ext4 - Re: [PATCH v3 1/2] ext4: commit super block if fs record error when journal record without error

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Message-ID: <63EDF795.7030204@huawei.com>
Date:   Thu, 16 Feb 2023 17:29:57 +0800
From:   "yebin (H)" <yebin10@...wei.com>
To:     Baokun Li <libaokun1@...wei.com>, Ye Bin <yebin@...weicloud.com>,
        <tytso@....edu>, <adilger.kernel@...ger.ca>,
        <linux-ext4@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, <jack@...e.cz>
Subject: Re: [PATCH v3 1/2] ext4: commit super block if fs record error when
 journal record without error



On 2023/2/16 17:17, Baokun Li wrote:
> On 2023/2/16 15:44, yebin (H) wrote:
>>
>>
>> On 2023/2/16 15:17, Baokun Li wrote:
>>> On 2023/2/14 10:29, Ye Bin wrote:
>>>> From: Ye Bin <yebin10@...wei.com>
>>>>
>>>> Now, 'es->s_state' maybe covered by recover journal. And journal errno
>>>> maybe not recorded in journal sb as IO error. ext4_update_super() only
>>>> update error information when 'sbi->s_add_error_count' large than 
>>>> zero.
>>>> Then 'EXT4_ERROR_FS' flag maybe lost.
>>>> To solve above issue commit error information after recover journal.
>>>>
>>>> Signed-off-by: Ye Bin <yebin10@...wei.com>
>>>> ---
>>>>   fs/ext4/super.c | 12 ++++++++++++
>>>>   1 file changed, 12 insertions(+)
>>>>
>>>> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
>>>> index dc3907dff13a..b94754ba8556 100644
>>>> --- a/fs/ext4/super.c
>>>> +++ b/fs/ext4/super.c
>>>> @@ -5932,6 +5932,18 @@ static int ext4_load_journal(struct 
>>>> super_block *sb,
>>>>           goto err_out;
>>>>       }
>>>>   +    if (unlikely(es->s_error_count && 
>>>> !jbd2_journal_errno(journal) &&
>>>> +             !(le16_to_cpu(es->s_state) & EXT4_ERROR_FS))) {
>>>> +        EXT4_SB(sb)->s_mount_state |= EXT4_ERROR_FS;
>>>> +        es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
>>>> +        err = ext4_commit_super(sb);
>>>> +        if (err) {
>>>> +            ext4_msg(sb, KERN_ERR,
>>>> +                 "Failed to commit error information, please 
>>>> repair fs force!");
>>>> +            goto err_out;
>>>> +        }
>>>> +    }
>>>> +
>>>>       EXT4_SB(sb)->s_journal = journal;
>>>>       err = ext4_clear_journal_err(sb, es);
>>>>       if (err) {
>>> I think we don't need such a complicated judgment, after the journal 
>>> replay and saving the error info,
>>> if there is EXT4_ERROR_FS flag in ext4_sb_info->s_mount_state, just 
>>> add this flag directly to es->s_state.
>>> This way the EXT4_ERROR_FS flag and the error message will be 
>>> written to disk the next time
>>
>> Thanks for your suggestion. There are two reasons for this:
>> 1. We want to write the error mark to the disk as soon as possible.
>> 2. Here we deal with the case where there is no error mark bit but 
>> there is an error record.
>> In this case, the file system should be marked with an error and the 
>> user should be prompted.
> The EXT4_ERROR_FS flag is always written to disk at the same time as 
> the error info,
> except when the journal is replayed. During journal replay the error 
> info is additionally
> copied to disk first, and the EXT4_ERROR_FS flag in the sbi is not 
> written to disk until
> the ext4_put_super() is called. It is only when a failure occurs 
> during this time that
> there is an error info but no EXT4_ERROR_FS flag. So we just need to 
> make sure that
> the EXT4_ERROR_FS flag is also written to disk at the same time as the 
> error info
> after the journal replay.
The situation you said is based on the situation after the repair. What 
about the existing
image with such inconsistency?
>>> ext4_commit_super() is executed. The code change is as follows:
>>>
>>> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
>>> index 260c1b3e3ef2..341b11c589b3 100644
>>> --- a/fs/ext4/super.c
>>> +++ b/fs/ext4/super.c
>>> @@ -5935,6 +5935,7 @@ static int ext4_load_journal(struct 
>>> super_block *sb,
>>>                         memcpy(((char *) es) + EXT4_S_ERR_START,
>>>                                save, EXT4_S_ERR_LEN);
>>>                 kfree(save);
>>> +               es->s_state |= 
>>> cpu_to_le16(EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS);
>>>         }
>>>
>>>         if (err) {
>>>
>>
>>
>>