On Tue, 30 Sep 2014 13:00:36 +0200 heinzm@xxxxxxxxxx wrote:
> From: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
>
> Liong,
> thanks for the catch.
> Introduced minor modification utilizing the is_power_of_2() inline.
>
> ---
>
> If region_size is not supplied by userspace and the device is very
> large, there is a bug in current code preventing region_size from being
> correctly set.
>
>
> Signed-off-by: Lidong Zhong <lzhong@xxxxxxxx>
> Acked-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
> Tested-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
>
> ---
> drivers/md/dm-raid.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
> index 4880b69..264aef4 100644
> --- a/drivers/md/dm-raid.c
> +++ b/drivers/md/dm-raid.c
> @@ -325,8 +325,10 @@ static int validate_region_size(struct raid_set *rs, unsigned long region_size)
> */
> if (min_region_size > (1 << 13)) {
> /* If not a power of 2, make it the next power of 2 */
> - if (min_region_size & (min_region_size - 1))
> - region_size = 1 << fls(region_size);
> + if (is_power_of_2(min_region_size))
> + region_size = min_region_size;
> + else
> + region_size = 1 << fls(min_region_size);
> DMINFO("Choosing default region size of %lu sectors",
> region_size);
> } else {
If you really wanted to optimize, you could just do
region_size = roundup_pow_of_two(min_region_size);
there is all sorts of cool stuff in log2.h !!
NeilBrown
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