fs/qnx4/bitmap.c

   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 }