Re: [PATCH] mm: simplify get_next_ra_size

[Fengguang Wu]

Looks good to me, thanks!

Reviewed-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>

On Sun, Oct 28, 2018 at 02:13:26PM +0800, Gao Xiang wrote:
> It's a trivial simplification for get_next_ra_size and
> clear enough for humans to understand.
>
> It also fixes potential overflow if ra->size(< ra_pages) is too large.
>
> Cc: Fengguang Wu <fengguang.wu@xxxxxxxxx>
> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxx>
> ---
> mm/readahead.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/mm/readahead.c b/mm/readahead.c
> index 4e63014..205ac34 100644
> --- a/mm/readahead.c
> +++ b/mm/readahead.c
> @@ -272,17 +272,15 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max)
>  *  return it as the new window size.
>  */
> static unsigned long get_next_ra_size(struct file_ra_state *ra,
> -						unsigned long max)
> +				      unsigned long max)
> {
> 	unsigned long cur = ra->size;
> -	unsigned long newsize;
>
> 	if (cur < max / 16)
> -		newsize = 4 * cur;
> -	else
> -		newsize = 2 * cur;
> -
> -	return min(newsize, max);
> +		return 4 * cur;
> +	if (cur <= max / 2)
> +		return 2 * cur;
> +	return max;
> }
>
> /*
> --
> 2.7.4