Re: [PATCH 10/10] udf: constify udf_bitmap_lookup array

Marcin Slusarz
2008-02-02T21:37:52Z

On Thu, Jan 31, 2008 at 05:52:44PM +0100, Jan Kara wrote:
> On Wed 30-01-08 22:04:00, marcin.slusarz@gmail.com wrote:
> > udf_bitmap_lookup never changes, so constify it
> >
> > Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
> > Cc: Jan Kara <jack@suse.cz>
> Hmm, rather than doing this, could you change the function to use
> standard functions for counting set bits? I guess bitmap_weight() in
> include/linux/bitmap.h should be what we need... Thanks.

---
udf: convert udf_count_free_bitmap to use bitmap_weight

replace handwritten bits counting with bitmap_weight

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Jan Kara <jack@suse.cz>
---
fs/udf/super.c | 17 +++++------------
1 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 3afe764..0dcee12 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -53,6 +53,7 @@
#include <linux/vfs.h>
#include <linux/vmalloc.h>
#include <linux/errno.h>
+#include <linux/bitmap.h>
#include <asm/byteorder.h>

#include <linux/udf_fs.h>
@@ -1969,10 +1970,6 @@ static int udf_statfs(struct dentry *dentry, struct kstatfs *buf)
return 0;
}

-static unsigned char udf_bitmap_lookup[16] = {
- 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4
-};
-
static unsigned int udf_count_free_bitmap(struct super_block *sb,
struct udf_bitmap *bitmap)
{
@@ -1982,7 +1979,6 @@ static unsigned int udf_count_free_bitmap(struct super_block *sb,
int block = 0, newblock;
kernel_lb_addr loc;
uint32_t bytes;
- uint8_t value;
uint8_t *ptr;
uint16_t ident;
struct spaceBitmapDesc *bm;
@@ -2008,13 +2004,10 @@ static unsigned int udf_count_free_bitmap(struct super_block *sb,
ptr = (uint8_t *)bh->b_data;

while (bytes > 0) {
- while ((bytes > 0) && (index < sb->s_blocksize)) {
- value = ptr[index];
- accum += udf_bitmap_lookup[value & 0x0f];
- accum += udf_bitmap_lookup[value >> 4];
- index++;
- bytes--;
- }
+ u32 cur_bytes = min_t(u32, bytes, sb->s_blocksize - index);
+ accum += bitmap_weight((const unsigned long *)(ptr + index),
+ cur_bytes * 8);
+ bytes -= cur_bytes;
if (bytes) {
brelse(bh);
newblock = udf_get_lb_pblock(sb, loc, ++block);
--
1.5.3.7