diff options
author | Akinobu Mita <akinobu.mita@gmail.com> | 2012-07-30 14:41:08 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-07-30 17:25:16 -0700 |
commit | 6017b485caeae5915956190b4f3d8307021e785d (patch) | |
tree | d2f3acfc4b8ea70db019367c3561ee272343a643 /fs/ext4/bitmap.c | |
parent | 10d470849a7c6dd360e8ad4770160ad7af9adb4b (diff) |
ext4: use memweight()
Convert ext4_count_free() to use memweight() instead of table lookup
based counting clear bits implementation. This change only affects the
code segments enabled by EXT4FS_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 change.
- Remove unnecessary map == NULL check in ext4_count_free() which
always takes non-null pointer as the memory area.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
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>
Diffstat (limited to 'fs/ext4/bitmap.c')
-rw-r--r-- | fs/ext4/bitmap.c | 9 |
1 files changed, 1 insertions, 8 deletions
diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c index a94b9c63ee5..f8716eab999 100644 --- a/fs/ext4/bitmap.c +++ b/fs/ext4/bitmap.c @@ -11,16 +11,9 @@ #include <linux/jbd2.h> #include "ext4.h" -static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0}; - unsigned int ext4_count_free(char *bitmap, unsigned int numchars) { - unsigned int i, sum = 0; - - for (i = 0; i < numchars; i++) - sum += nibblemap[bitmap[i] & 0xf] + - nibblemap[(bitmap[i] >> 4) & 0xf]; - return sum; + return numchars * BITS_PER_BYTE - memweight(bitmap, numchars); } int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group, |