Linux Kernel  3.7.1
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bitmap.c
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1 /*
2  * QNX4 file system, Linux implementation.
3  *
4  * Version : 0.2.1
5  *
6  * Using parts of the xiafs filesystem.
7  *
8  * History :
9  *
10  * 28-05-1998 by Richard Frowijn : first release.
11  * 20-06-1998 by Frank Denis : basic optimisations.
12  * 25-06-1998 by Frank Denis : qnx4_is_free, qnx4_set_bitmap, qnx4_bmap .
13  * 28-06-1998 by Frank Denis : qnx4_free_inode (to be fixed) .
14  */
15 
16 #include <linux/buffer_head.h>
17 #include <linux/bitops.h>
18 #include "qnx4.h"
19 
20 unsigned long qnx4_count_free_blocks(struct super_block *sb)
21 {
22  int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
23  int total = 0;
24  int total_free = 0;
25  int offset = 0;
26  int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
27  struct buffer_head *bh;
28 
29  while (total < size) {
30  int bytes = min(size - total, QNX4_BLOCK_SIZE);
31 
32  if ((bh = sb_bread(sb, start + offset)) == NULL) {
33  printk(KERN_ERR "qnx4: I/O error in counting free blocks\n");
34  break;
35  }
36  total_free += bytes * BITS_PER_BYTE -
37  memweight(bh->b_data, bytes);
38  brelse(bh);
39  total += bytes;
40  offset++;
41  }
42 
43  return total_free;
44 }