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>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 2666e5b..be0aa42 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -55,6 +55,7 @@
 #include <linux/errno.h>
 #include <linux/mount.h>
 #include <linux/seq_file.h>
+#include <linux/bitmap.h>
 #include <asm/byteorder.h>
 
 #include "udf_sb.h"
@@ -1958,10 +1959,6 @@ 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)
 {
@@ -1971,7 +1968,6 @@ 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;
@@ -1997,13 +1993,10 @@ 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);