linux/fs/qnx4/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
  20unsigned 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}
  45
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