ext2: use memweight()

Convert ext2_count_free() to use memweight() instead of table lookup
based counting clear bits implementation.  This change only affects the
code segments enabled by EXT2FS_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 ext2_count_free() which
  always takes non-null pointer as the memory area.

- Fix printk format warning that only reveals with EXT2FS_DEBUG.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Akinobu Mita 2012-07-30 14:41:05 -07:00 committed by Linus Torvalds
parent a75613ec73
commit ecd0afa3ce
2 changed files with 3 additions and 12 deletions

View File

@ -1444,19 +1444,9 @@ ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
#ifdef EXT2FS_DEBUG
static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
unsigned long ext2_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 /* EXT2FS_DEBUG */

View File

@ -644,6 +644,7 @@ unsigned long ext2_count_free_inodes (struct super_block * sb)
}
brelse(bitmap_bh);
printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
(unsigned long)
percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter),
desc_count, bitmap_count);
return desc_count;