linux-kernel - Re: [PATCH RESEND v2 3/5] sbitmap: rewrite sbitmap_find_bit_in

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Date:   Thu, 22 Dec 2022 13:23:24 +0100
From:   Jan Kara <jack@...e.cz>
To:     Kemeng Shi <shikemeng@...weicloud.com>
Cc:     axboe@...nel.dk, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, jack@...e.cz, kbusch@...nel.org
Subject: Re: [PATCH RESEND v2 3/5] sbitmap: rewrite sbitmap_find_bit_in_index
 to reduce repeat code

On Thu 22-12-22 22:33:51, Kemeng Shi wrote:
> Rewrite sbitmap_find_bit_in_index as following:
> 1. Rename sbitmap_find_bit_in_index to sbitmap_find_bit_in_word
> 2. Accept "struct sbitmap_word *" directly instead of accepting
> "struct sbitmap *" and "int index" to get "struct sbitmap_word *".
> 3. Accept depth/shallow_depth and wrap for __sbitmap_get_word from caller
> to support need of both __sbitmap_get_shallow and __sbitmap_get.
> 
> With helper function sbitmap_find_bit_in_word, we can remove repeat
> code in __sbitmap_get_shallow to find bit considring deferred clear.
> 
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
> ---
>  lib/sbitmap.c | 29 ++++++++++++++---------------
>  1 file changed, 14 insertions(+), 15 deletions(-)

Just one style nit below. Please fix that up. Otherwise feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

> diff --git a/lib/sbitmap.c b/lib/sbitmap.c
> index 11e75f4040fb..3f7e276a427d 100644
> --- a/lib/sbitmap.c
> +++ b/lib/sbitmap.c
> @@ -167,15 +167,16 @@ static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
>  	return nr;
>  }
>  
> -static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
> -				     unsigned int alloc_hint)
> +static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
> +				    unsigned int depth,
> +				    unsigned int alloc_hint,
> +				    bool wrap)
>  {
> -	struct sbitmap_word *map = &sb->map[index];
>  	int nr;
>  
>  	do {
> -		nr = __sbitmap_get_word(&map->word, __map_depth(sb, index),
> -					alloc_hint, !sb->round_robin);
> +		nr = __sbitmap_get_word(&map->word, depth,
> +					alloc_hint, wrap);
>  		if (nr != -1)
>  			break;
>  		if (!sbitmap_deferred_clear(map))
> @@ -203,7 +204,8 @@ static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
>  		alloc_hint = 0;
>  
>  	for (i = 0; i < sb->map_nr; i++) {
> -		nr = sbitmap_find_bit_in_index(sb, index, alloc_hint);
> +		nr = sbitmap_find_bit_in_word(&sb->map[index], __map_depth(sb, index),

Please avoid lines over 80 characters.

> +					      alloc_hint, !sb->round_robin);
>  		if (nr != -1) {
>  			nr += index << sb->shift;
>  			break;

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