Re: [PATCH] md/raid10:using conf->chunk_mask instead "chunk_secotrs - 1"

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On Tue, 17 Apr 2012 16:49:50 +0800 "majianpeng" <majianpeng@xxxxxxxxx> wrote:

> >From 2c637bca4e50e87f7b4e6b3abce27f8cd935fd92 Mon Sep 17 00:00:00 2001
> From: majianpeng <majianpeng@xxxxxxxxx>
> Date: Tue, 17 Apr 2012 16:47:07 +0800
> Subject: [PATCH] md/raid10:using conf->chunk_mask instead "chunk_secotrs -
>  1".
> 
> 
> Signed-off-by: majianpeng <majianpeng@xxxxxxxxx>
> ---
>  drivers/md/raid10.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index c8dbb84..5734d92 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -601,7 +601,7 @@ static int raid10_mergeable_bvec(struct request_queue *q,
>  	unsigned int bio_sectors = bvm->bi_size >> 9;
>  
>  	if (conf->near_copies < conf->raid_disks) {
> -		max = (chunk_sectors - ((sector & (chunk_sectors - 1))
> +		max = (chunk_sectors - ((sector & conf->chunk_mask)
>  					+ bio_sectors)) << 9;
>  		if (max < 0)
>  			/* bio_add cannot handle a negative return */


Doesn't apply to latest code (in for-next).

And are you sure that it is actually an improvement?  'chunk_sectors' is
probably in a register, conf->chunk_mask is not.

I really am not interested in micro-optimisations like this (as I have said
before).

An please try to fix up your mailing process so that patch doesn't have
duplicate headers.

NeilBrown

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