2023-10-23 01:36:12

by Gou Hao

Subject: [PATCH] ext4: delete redundant calculations in ext4_mb_get_buddy_page_lock()

'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 <[email protected]>
Signed-off-by: Gou Hao <[email protected]>
---
fs/ext4/mballoc.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

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);
if (!page)
return -ENOMEM;
BUG_ON(page->mapping != inode->i_mapping);
--
2.34.1

2023-10-23 11:46:29

by Jan Kara

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 <[email protected]>
> Signed-off-by: Gou Hao <[email protected]>

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 <[email protected]>
SUSE Labs, CR

2023-10-24 02:36:18

by Gou Hao

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 <[email protected]>
>> Signed-off-by: Gou Hao <[email protected]>
> 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 <[email protected]>