Commit 10d47084 authored Jul 30, 2012 by Akinobu Mita Committed by Linus Torvalds Jul 30, 2012

ext3: use memweight()



Convert ext3_count_free() to use memweight() instead of table lookup
based counting clear bits implementation.  This change only affects the
code segments enabled by EXT3FS_DEBUG.

Note that this memweight() call can't be replaced with a single
bitmap_weight() call, although the pointer to the memory area is aligned
to long-word boundary.  Because the size of the memory area may not be a
multiple of BITS_PER_LONG, then it returns wrong value on big-endian
architecture.

This also includes the following changes.

- Remove unnecessary map == NULL check in ext3_count_free() which
  always takes non-null pointer as the memory area.

- Fix printk format warning that only reveals with EXT3FS_DEBUG.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ecd0afa3

fs/ext3/balloc.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1813,7 +1813,7 @@ ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)
		brelse(bitmap_bh);
		printk("ext3_count_free_blocks: stored = "E3FSBLK
		", computed = "E3FSBLK", "E3FSBLK"\n",
		le32_to_cpu(es->s_free_blocks_count),
		(ext3_fsblk_t)le32_to_cpu(es->s_free_blocks_count),
		desc_count, bitmap_count);
		return bitmap_count;
		#else

fs/ext3/bitmap.c

+1 −11

Original line number	Diff line number	Diff line
		@@ -11,19 +11,9 @@

		#ifdef EXT3FS_DEBUG

		static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};

		unsigned long ext3_count_free (struct buffer_head * map, unsigned int numchars)
		{
		unsigned int i;
		unsigned long sum = 0;

		if (!map)
		return (0);
		for (i = 0; i < numchars; i++)
		sum += nibblemap[map->b_data[i] & 0xf] +
		nibblemap[(map->b_data[i] >> 4) & 0xf];
		return (sum);
		return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
		}

		#endif /* EXT3FS_DEBUG */

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