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

Jan Kara
2008-02-04T19:15:19Z

On Sat 02-02-08 22:37:07, Marcin Slusarz wrote:
> 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>
Acked-by: Jan Kara <jack@suse.cz>

Honza
> ---
> 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
>
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR