linux-ext4 - Re: [PATCH v3 13/19] ext4: call ext4_mb_mark_group_bb in ext4_free_blocks

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Message-ID: <ZGCqkC+UHebpPSwm@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com>
Date:   Sun, 14 May 2023 15:02:00 +0530
From:   Ojaswin Mujoo <ojaswin@...ux.ibm.com>
To:     Kemeng Shi <shikemeng@...weicloud.com>
Cc:     tytso@....edu, adilger.kernel@...ger.ca,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 13/19] ext4: call ext4_mb_mark_group_bb in
 ext4_free_blocks_simple

On Mon, Apr 17, 2023 at 07:06:11PM +0800, Kemeng Shi wrote:
> call ext4_mb_mark_group_bb in ext4_free_blocks_simple to:
> 1. remove repeat code
> 2. pair update of free_clusters in ext4_mb_new_blocks_simple.
> 3. add missing ext4_lock_group/ext4_unlock_group protection.
> 
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>

Correct me if I'm wrong but I think we will never try to clear bitmap
bits for a BLOCK_UNINIT BG right. Maybe if that's the case we can add a
WARN_ON as follows in ext4_mb_mark_group_bb():

	if (ext4_has_group_desc_csum(sb) &&
		(gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {

		WARN_ON(mc->state == 0);
		...

	}

Other than that the patch looks good, feel free to add:

Reviewed-by: Ojaswin Mujoo <ojaswin@...ux.ibm.com>

Regards,
ojaswin
> ---
>  fs/ext4/mballoc.c | 37 +++++--------------------------------
>  1 file changed, 5 insertions(+), 32 deletions(-)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index ba165dc07890..623508115d98 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -6063,43 +6063,16 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
>  static void ext4_free_blocks_simple(struct inode *inode, ext4_fsblk_t block,
>  					unsigned long count)
>  {
> -	struct buffer_head *bitmap_bh;
> +	struct ext4_mark_context mc = {
> +		.sb = inode->i_sb,
> +		.state = 0,
> +	};
>  	struct super_block *sb = inode->i_sb;
> -	struct ext4_group_desc *gdp;
> -	struct buffer_head *gdp_bh;
>  	ext4_group_t group;
>  	ext4_grpblk_t blkoff;
> -	int already_freed = 0, err, i;
>  
>  	ext4_get_group_no_and_offset(sb, block, &group, &blkoff);
> -	bitmap_bh = ext4_read_block_bitmap(sb, group);
> -	if (IS_ERR(bitmap_bh)) {
> -		pr_warn("Failed to read block bitmap\n");
> -		return;
> -	}
> -	gdp = ext4_get_group_desc(sb, group, &gdp_bh);
> -	if (!gdp)
> -		goto err_out;
> -
> -	for (i = 0; i < count; i++) {
> -		if (!mb_test_bit(blkoff + i, bitmap_bh->b_data))
> -			already_freed++;
> -	}
> -	mb_clear_bits(bitmap_bh->b_data, blkoff, count);
> -	err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh);
> -	if (err)
> -		goto err_out;
> -	ext4_free_group_clusters_set(
> -		sb, gdp, ext4_free_group_clusters(sb, gdp) +
> -		count - already_freed);
> -	ext4_block_bitmap_csum_set(sb, gdp, bitmap_bh);
> -	ext4_group_desc_csum_set(sb, group, gdp);
> -	ext4_handle_dirty_metadata(NULL, NULL, gdp_bh);
> -	sync_dirty_buffer(bitmap_bh);
> -	sync_dirty_buffer(gdp_bh);
> -
> -err_out:
> -	brelse(bitmap_bh);
> +	ext4_mb_mark_group_bb(&mc, group, blkoff, count);
>  }
>  
>  /**
> -- 
> 2.30.0
>