Re: [PATCH] md/raid10: remove unnecessary checks with 'first'

[NeilBrown <neilb@suse.com>]

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On Sat, Apr 01 2017, Guoqing Jiang wrote:

> Since the value of first is always '1', we can
> set min_offset_diff directly.

Alternately, maybe the fact that first is always '1', is a sign of a bug
that should be fixed.

The calculation of "min_offset_diff" doesn't make much sense now.  It is
just the last_offset_diff.

I think the correct fix is to set "first = 0;" at the end of the
rdev_for_each() loop.

Thanks for spotting this.

NeilBrown

>
> Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
> ---
>  drivers/md/raid10.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 0f13d57..edaf8f4 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -3702,7 +3702,6 @@ static int raid10_run(struct mddev *mddev)
>  	struct md_rdev *rdev;
>  	sector_t size;
>  	sector_t min_offset_diff = 0;
> -	int first = 1;
>  	bool discard_supported = false;
>  
>  	if (mddev->private == NULL) {
> @@ -3758,8 +3757,7 @@ static int raid10_run(struct mddev *mddev)
>  			diff = -diff;
>  		if (diff < 0)
>  			diff = 0;
> -		if (first || diff < min_offset_diff)
> -			min_offset_diff = diff;
> +		min_offset_diff = diff;
>  
>  		if (mddev->gendisk)
>  			disk_stack_limits(mddev->gendisk, rdev->bdev,
> @@ -4140,7 +4138,6 @@ static int raid10_start_reshape(struct mddev *mddev)
>  
>  	unsigned long before_length, after_length;
>  	sector_t min_offset_diff = 0;
> -	int first = 1;
>  	struct geom new;
>  	struct r10conf *conf = mddev->private;
>  	struct md_rdev *rdev;
> @@ -4169,8 +4166,7 @@ static int raid10_start_reshape(struct mddev *mddev)
>  				diff = -diff;
>  			if (diff < 0)
>  				diff = 0;
> -			if (first || diff < min_offset_diff)
> -				min_offset_diff = diff;
> +			min_offset_diff = diff;
>  		}
>  	}
>  
> -- 
> 2.6.6

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