Root/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
20static void count_bits(register const char *bmPart, register int size,
21               int *const tf)
22{
23    char b;
24    int tot = *tf;
25
26    if (size > QNX4_BLOCK_SIZE) {
27        size = QNX4_BLOCK_SIZE;
28    }
29    do {
30        b = *bmPart++;
31        tot += 8 - hweight8(b);
32        size--;
33    } while (size != 0);
34    *tf = tot;
35}
36
37unsigned long qnx4_count_free_blocks(struct super_block *sb)
38{
39    int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
40    int total = 0;
41    int total_free = 0;
42    int offset = 0;
43    int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
44    struct buffer_head *bh;
45
46    while (total < size) {
47        if ((bh = sb_bread(sb, start + offset)) == NULL) {
48            printk(KERN_ERR "qnx4: I/O error in counting free blocks\n");
49            break;
50        }
51        count_bits(bh->b_data, size - total, &total_free);
52        brelse(bh);
53        total += QNX4_BLOCK_SIZE;
54        offset++;
55    }
56
57    return total_free;
58}
59

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