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@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
Cc: linux-ext4@xxxxxxxxxxxxxxx
---
v3: rewrite to keep ext3_count_free() as a wrapper for memweight()
fs/ext3/balloc.c | 2 +-
fs/ext3/bitmap.c | 12 +-----------
2 files changed, 2 insertions(+), 12 deletions(-)
diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
index 25cd608..90d901f 100644
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -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
diff --git a/fs/ext3/bitmap.c b/fs/ext3/bitmap.c
index 909d13e..ef9c643 100644
--- a/fs/ext3/bitmap.c
+++ b/fs/ext3/bitmap.c
@@ -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 */
--
1.7.7.6
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
