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Subject: Re: [PATCH 2/3] ext4: WANR_ON when detect abnormal
 'i_reserved_data_blocks'
To:     Jan Kara <jack@suse.cz>, Ye Bin <yebin10@huawei.com>
References: <20221117014246.610202-1-yebin@huaweicloud.com>
 <20221117014246.610202-3-yebin@huaweicloud.com>
 <20221121094715.gpha7rkijbwr5r47@quack3>
CC:     <tytso@mit.edu>, <adilger.kernel@dilger.ca>,
        <linux-ext4@vger.kernel.org>, <linux-kernel@vger.kernel.org>
From:   "yebin (H)" <yebin10@huawei.com>
Message-ID: <637B5D87.4000806@huawei.com>
Date:   Mon, 21 Nov 2022 19:14:15 +0800
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On 2022/11/21 17:47, Jan Kara wrote:
> On Thu 17-11-22 09:42:45, Ye Bin wrote:
>> From: Ye Bin <yebin10@huawei.com>
>>
>> If 'i_reserved_data_blocks' is not cleared which mean something wrong
>> with code, so emit WARN_ON to capture this abnormal closer to the first
>> scene.
>>
>> Signed-off-by: Ye Bin <yebin10@huawei.com>
>> ---
>>   fs/ext4/super.c | 13 ++++++++-----
>>   1 file changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
>> index 63ef74eb8091..30885a6fe18b 100644
>> --- a/fs/ext4/super.c
>> +++ b/fs/ext4/super.c
>> @@ -1385,11 +1385,14 @@ static void ext4_destroy_inode(struct inode *inode)
>>   		dump_stack();
>>   	}
>>   
>> -	if (EXT4_I(inode)->i_reserved_data_blocks)
>> -		ext4_msg(inode->i_sb, KERN_ERR,
>> -			 "Inode %lu (%p): i_reserved_data_blocks (%u) not cleared!",
>> -			 inode->i_ino, EXT4_I(inode),
>> -			 EXT4_I(inode)->i_reserved_data_blocks);
>> +	if (EXT4_I(inode)->i_reserved_data_blocks) {
>> +		ext4_warning(inode->i_sb, "Inode %lu (%p): "
>> +			    "i_reserved_data_blocks (%u) not cleared!",
>> +			     inode->i_ino, EXT4_I(inode),
>> +			     EXT4_I(inode)->i_reserved_data_blocks);
>> +
>> +		WARN_ON(1);
>> +	}
> Hum, so I'd think that if this happens, the free space accounting is likely
> wrong so we might as well just force the filesystem to error mode with
> ext4_error() to force fsck?  I also gives a good chance to various test
> systems to detect there is some problem so we don't need the WARN_ON then?
> What do others think?
>
> 								Honza
Thanks for your advice, use ext4_error() maybe is suitable and also 
testable.