linux-kernel - Re: [PATCH 04/21] ext4: get correct ext4_group_info in ext4_mb_prefetch

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Message-Id: <87ttzkiybi.fsf@doe.com>
Date:   Fri, 17 Feb 2023 12:16:25 +0530
From:   Ritesh Harjani (IBM) <ritesh.list@...il.com>
To:     Kemeng Shi <shikemeng@...weicloud.com>, tytso@....edu,
        adilger.kernel@...ger.ca, jack@...e.cz
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/21] ext4: get correct ext4_group_info in ext4_mb_prefetch_fini

Kemeng Shi <shikemeng@...weicloud.com> writes:

> We always get ext4_group_desc with group + 1 and ext4_group_info with
> group to check if we need do initialize ext4_group_info for the group.
> Just get ext4_group_desc with group for ext4_group_info initialization
> check.
>
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
> ---
>  fs/ext4/mballoc.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 352ac9139fee..f24f80ecf318 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2570,13 +2570,13 @@ void ext4_mb_prefetch_fini(struct super_block *sb, ext4_group_t group,
>  			   unsigned int nr)
>  {
>  	while (nr-- > 0) {
> -		struct ext4_group_desc *gdp = ext4_get_group_desc(sb, group,
> -								  NULL);
> -		struct ext4_group_info *grp = ext4_get_group_info(sb, group);
> +		struct ext4_group_desc *gdp;
> +		struct ext4_group_info *grp;

We can even declare these variables at the begining of the function like
in [1]. Also I would advise to rearrange any "fixes" patches at the
begining of the patch series and "cleanup" patches at the end.
e.g. this looks like a fix to me.

That way it is sometimes easier for people to cherry-pick any fixes if
required in their older kernel trees. ;)

[1]: https://lore.kernel.org/all/85bbcb3774e38de65b737ef0000241ddbdda73aa.1674822311.git.ojaswin@linux.ibm.com/

-ritesh

>
>  		if (!group)
>  			group = ext4_get_groups_count(sb);
>  		group--;
> +		gdp = ext4_get_group_desc(sb, group, NULL);
>  		grp = ext4_get_group_info(sb, group);
>
>  		if (EXT4_MB_GRP_NEED_INIT(grp) &&
> --
> 2.30.0