linux-ext4 - Re: [PATCH] ext4: Enable meta_bg only when new desc blocks are needed

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Message-Id: <87o7bsovn6.fsf@doe.com>
Date: Wed, 06 Mar 2024 09:32:21 +0530
From: Ritesh Harjani (IBM) <ritesh.list@...il.com>
To: Srivathsa Dara <srivathsa.d.dara@...cle.com>, linux-ext4@...r.kernel.org
Cc: tytso@....edu, adilger.kernel@...ger.ca, rajesh.sivaramasubramaniom@...cle.com, junxiao.bi@...cle.com
Subject: Re: [PATCH] ext4: Enable meta_bg only when new desc blocks are needed

Srivathsa Dara <srivathsa.d.dara@...cle.com> writes:

> This patch addresses an issue observed when resize_inode is disabled

Other than "meta_bg unwatedly getting enabled when not required", is
there any other issue you observed?

> and an online extension of a filesysyem is performed. When a filesystem
> is expanded to a size that does not require a addition of a new
> descriptor block, the meta_bg feature is being enabled even though no
> part of the filesystem uses this layout.
>
> This patch ensures that the meta_bg feature is only enabled if
> any of the added block groups utilize meta_bg layout.

Make sense to me. 

>
> Signed-off-by: Srivathsa Dara <srivathsa.d.dara@...cle.com>
> ---
>  fs/ext4/resize.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
> index 928700d57eb6..99b52f26e818 100644
> --- a/fs/ext4/resize.c
> +++ b/fs/ext4/resize.c
> @@ -1996,7 +1996,7 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
>  		}
>  	}
>  
> -	if ((!resize_inode && !meta_bg) || n_blocks_count == o_blocks_count) {
> +	if ((!resize_inode && !meta_bg && n_desc_blocks > o_desc_blocks) || n_blocks_count == o_blocks_count) {

Beyond 80 chars line. You might want to fix that.

-ritesh

>  		err = ext4_convert_meta_bg(sb, resize_inode);
>  		if (err)
>  			goto out;
> -- 
> 2.39.3