linux-kernel - Re: [PATCH v2 5/8] ext4: avoid dividing by 0 in mb_update_avg_fragment

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Message-ID: <20240104104331.udagyt3wv4xfchgq@quack3>
Date: Thu, 4 Jan 2024 11:43:31 +0100
From: Jan Kara <jack@...e.cz>
To: Baokun Li <libaokun1@...wei.com>
Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca,
	jack@...e.cz, ritesh.list@...il.com, linux-kernel@...r.kernel.org,
	yi.zhang@...wei.com, yangerkun@...wei.com, yukuai3@...wei.com
Subject: Re: [PATCH v2 5/8] ext4: avoid dividing by 0 in
 mb_update_avg_fragment_size() when block bitmap corrupt

On Thu 21-12-23 23:05:55, Baokun Li wrote:
> Determine if bb_fragments is 0 instead of determining bb_free to eliminate
> the risk of dividing by zero when the block bitmap is corrupted.
> 
> Signed-off-by: Baokun Li <libaokun1@...wei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ext4/mballoc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 1f15774971d7..03500aec43ac 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -842,7 +842,7 @@ mb_update_avg_fragment_size(struct super_block *sb, struct ext4_group_info *grp)
>  	struct ext4_sb_info *sbi = EXT4_SB(sb);
>  	int new_order;
>  
> -	if (!test_opt2(sb, MB_OPTIMIZE_SCAN) || grp->bb_free == 0)
> +	if (!test_opt2(sb, MB_OPTIMIZE_SCAN) || grp->bb_fragments == 0)
>  		return;
>  
>  	new_order = mb_avg_fragment_size_order(sb,
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR