linux-kernel - Re: [PATCH 6/8] omfs: add bitmap routines

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Date:	Sun, 20 Apr 2008 00:03:12 +0200
From:	Marcin Slusarz <marcin.slusarz@...il.com>
To:	Bob Copeland <me@...copeland.com>
Cc:	akpm@...ux-foundation.org, hch@...radead.org,
	alan@...rguk.ukuu.org.uk, miklos@...redi.hu,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 6/8] omfs: add bitmap routines

On Sat, Apr 19, 2008 at 04:37:35PM -0400, Bob Copeland wrote:
> +unsigned long omfs_count_free(struct super_block *sb)
> +{
> +	unsigned int i, j;
> +	u64 *map;
> +	unsigned long sum = 0;
> +	struct omfs_sb_info *sbi = OMFS_SB(sb);
> +
> +	for (i = 0; i < sbi->s_imap_size; i++) {
> +		map = (u64 *) sbi->s_imap[i];
> +		for (j = 0; j < sb->s_blocksize / 8; j++)
> +			sum += hweight64(~map[j]);
> +	}
> +	return sum;
> +}
I think inner loop can be replaced with something like:
sum += sb->s_blocksize * 8 - bitmap_weight(map, sb->s_blocksize * 8);

Marcin
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