linux-ext4 - Re: [PATCH 2/3] ext4: WANR_ON when detect abnormal 'i_reserved_data

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Date:   Mon, 21 Nov 2022 10:47:15 +0100
From:   Jan Kara <jack@...e.cz>
To:     Ye Bin <yebin@...weicloud.com>
Cc:     tytso@....edu, adilger.kernel@...ger.ca,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        jack@...e.cz, Ye Bin <yebin10@...wei.com>
Subject: Re: [PATCH 2/3] ext4: WANR_ON when detect abnormal
 'i_reserved_data_blocks'

On Thu 17-11-22 09:42:45, Ye Bin wrote:
> From: Ye Bin <yebin10@...wei.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@...wei.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
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR