fs/qnx4/bitmap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * QNX4 file system, Linux implementation.
   4  *
   5  * Version : 0.2.1
   6  *
   7  * Using parts of the xiafs filesystem.
   8  *
   9  * History :
  10  *
  11  * 28-05-1998 by Richard Frowijn : first release.
  12  * 20-06-1998 by Frank Denis : basic optimisations.
  13  * 25-06-1998 by Frank Denis : qnx4_is_free, qnx4_set_bitmap, qnx4_bmap .
  14  * 28-06-1998 by Frank Denis : qnx4_free_inode (to be fixed) .
  15  */
  16
  17 #include <linux/buffer_head.h>
  18 #include <linux/bitops.h>
  19 #include "qnx4.h"
  20
  21 unsigned long qnx4_count_free_blocks(struct super_block *sb)
  22 {
  23         int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
  24         int total = 0;
  25         int total_free = 0;
  26         int offset = 0;
  27         int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
  28         struct buffer_head *bh;
  29
  30         while (total < size) {
  31                 int bytes = min(size - total, QNX4_BLOCK_SIZE);
  32
  33                 if ((bh = sb_bread(sb, start + offset)) == NULL) {
  34                         printk(KERN_ERR "qnx4: I/O error in counting free blocks\n");
  35                         break;
  36                 }
  37                 total_free += bytes * BITS_PER_BYTE -
  38                                 memweight(bh->b_data, bytes);
  39                 brelse(bh);
  40                 total += bytes;
  41                 offset++;
  42         }
  43
  44         return total_free;
  45 }