linux-kernel - Re: [PATCH] ext4: delete redundant calculations in ext4_mb_get_buddy_page

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Message-ID: <20231023114447.crn3bt4qdmkxkrxi@quack3>
Date:   Mon, 23 Oct 2023 13:44:47 +0200
From:   Jan Kara <jack@...e.cz>
To:     Gou Hao <gouhao@...ontech.com>
Cc:     tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        gouhaojake@....com
Subject: Re: [PATCH] ext4: delete redundant calculations in
 ext4_mb_get_buddy_page_lock()

On Mon 23-10-23 09:34:16, Gou Hao wrote:
> 'blocks_per_page' is always 1 after 'if (blocks_per_page >= 2)',
> 'pnum' and 'block' is equal in this case.
> 
> Signed-off-by: Gou Hao <gouhao@...ontech.com>
> Signed-off-by: Gou Hao <gouhaojake@....com>

No need for two signed-off-by here. Any one from you is enough :)

> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 454d5612641e..8442f5474b25 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -1456,9 +1456,7 @@ static int ext4_mb_get_buddy_page_lock(struct super_block *sb,
>  		return 0;
>  	}
>  
> -	block++;
> -	pnum = block / blocks_per_page;
> -	page = find_or_create_page(inode->i_mapping, pnum, gfp);
> +	page = find_or_create_page(inode->i_mapping, ++block, gfp);
						     ^^^ perhaps just
"block + 1" here? Maybe also add a comment before this call like:

	/* blocks_per_page == 1, hence we need another page for the buddy */

Otherwise the patch looks good!

								Honza

-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR