linux-kernel - Re: [PATCH v2 2/2] ext4: Ignore a stripe width of 1

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Message-ID: <4E20B55E.9080908@redhat.com>
Date:	Fri, 15 Jul 2011 16:47:10 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Dan Ehrenberg <dehrenberg@...gle.com>
CC:	"Theodore Ts'o" <tytso@....edu>,
	Andreas Dilger <adilger.kernel@...ger.ca>,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] ext4: Ignore a stripe width of 1

On 7/15/11 4:41 PM, Dan Ehrenberg wrote:
> If the stripe width was set to 1, then this patch will ignore
> that stripe width and ext4 will act as if the stripe width
> were 0 with respect to optimizing allocations.
> 
> Signed-off-by: Dan Ehrenberg <dehrenberg@...gle.com>

Thanks, I think this makes sense.

Reviewed-by: Eric Sandeen <sandeen@...hat.com>

> ---
>  fs/ext4/super.c |   22 ++++++++++++++++------
>  1 files changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 9ea71aa..0a3745b 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2383,17 +2383,27 @@ static unsigned long ext4_get_stripe_size(struct ext4_sb_info *sbi)
>  	unsigned long stride = le16_to_cpu(sbi->s_es->s_raid_stride);
>  	unsigned long stripe_width =
>  			le32_to_cpu(sbi->s_es->s_raid_stripe_width);
> +	int ret;
>  
>  	if (sbi->s_stripe && sbi->s_stripe <= sbi->s_blocks_per_group)
> -		return sbi->s_stripe;
> +		ret = sbi->s_stripe;
>  
> -	if (stripe_width <= sbi->s_blocks_per_group)
> -		return stripe_width;
> +	else if (stripe_width <= sbi->s_blocks_per_group)
> +		ret = stripe_width;
>  
> -	if (stride <= sbi->s_blocks_per_group)
> -		return stride;
> +	else if (stride <= sbi->s_blocks_per_group)
> +		ret = stride;
> +	else
> +		ret = 0;
>  
> -	return 0;
> +	/*
> +	 * If the stripe width is 1, this makes no sense and
> +	 * we set it to 0 to turn off stripe handling code.
> +	 */
> +	if (ret <= 1)
> +		ret = 0;
> +
> +	return ret;
>  }
>  
>  /* sysfs supprt */

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