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

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Date:   Tue, 24 Oct 2023 10:35:13 +0800
From:   Gou Hao <gouhao@...ontech.com>
To:     Jan Kara <jack@...e.cz>
Cc:     tytso@....edu, adilger.kernel@...ger.ca,
        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 10/23/23 19:44, Jan Kara wrote:

> 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 :)
ok
>> 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:

Yes, 'block +1' is better here, i will add a comment.

Thanks for your review.

> 	/* blocks_per_page == 1, hence we need another page for the buddy */
>
> Otherwise the patch looks good!
>
> 								Honza
>
-- 
thanks,
Gou Hao <gouhao@...ontech.com>