LXR linux/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
  21unsigned 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}
  46