linux-ext4 - Re: [PATCHv1 1/9] ext4: Correct cluster len and clusters changed accounting in ext4_mb_mark

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Date:   Mon, 7 Feb 2022 16:28:18 +0100
From:   Jan Kara <jack@...e.cz>
To:     Ritesh Harjani <riteshh@...ux.ibm.com>
Cc:     linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.cz>,
        Harshad Shirwadkar <harshadshirwadkar@...il.com>
Subject: Re: [PATCHv1 1/9] ext4: Correct cluster len and clusters changed
 accounting in ext4_mb_mark_bb

On Sat 05-02-22 19:39:50, Ritesh Harjani wrote:
> ext4_mb_mark_bb() currently wrongly calculates cluster len (clen) and
> flex_group->free_clusters. This patch fixes that.
> 
> Identified based on code review of ext4_mb_mark_bb() function.
> 
> Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>

Looks good. Feel free to add:

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

								Honza

> ---
>  fs/ext4/mballoc.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index c781974df9d0..2f117ce3bb73 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -3899,10 +3899,11 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
>  	struct ext4_sb_info *sbi = EXT4_SB(sb);
>  	ext4_group_t group;
>  	ext4_grpblk_t blkoff;
> -	int i, clen, err;
> +	int i, err;
>  	int already;
> +	unsigned int clen, clen_changed;
>  
> -	clen = EXT4_B2C(sbi, len);
> +	clen = EXT4_NUM_B2C(sbi, len);
>  
>  	ext4_get_group_no_and_offset(sb, block, &group, &blkoff);
>  	bitmap_bh = ext4_read_block_bitmap(sb, group);
> @@ -3923,6 +3924,7 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
>  		if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state)
>  			already++;
>  
> +	clen_changed = clen - already;
>  	if (state)
>  		ext4_set_bits(bitmap_bh->b_data, blkoff, clen);
>  	else
> @@ -3935,9 +3937,9 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
>  						group, gdp));
>  	}
>  	if (state)
> -		clen = ext4_free_group_clusters(sb, gdp) - clen + already;
> +		clen = ext4_free_group_clusters(sb, gdp) - clen_changed;
>  	else
> -		clen = ext4_free_group_clusters(sb, gdp) + clen - already;
> +		clen = ext4_free_group_clusters(sb, gdp) + clen_changed;
>  
>  	ext4_free_group_clusters_set(sb, gdp, clen);
>  	ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh);
> @@ -3947,10 +3949,13 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
>  
>  	if (sbi->s_log_groups_per_flex) {
>  		ext4_group_t flex_group = ext4_flex_group(sbi, group);
> +		struct flex_groups *fg = sbi_array_rcu_deref(sbi,
> +					   s_flex_groups, flex_group);
>  
> -		atomic64_sub(len,
> -			     &sbi_array_rcu_deref(sbi, s_flex_groups,
> -						  flex_group)->free_clusters);
> +		if (state)
> +			atomic64_sub(clen_changed, &fg->free_clusters);
> +		else
> +			atomic64_add(clen_changed, &fg->free_clusters);
>  	}
>  
>  	err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh);
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR