bitmap.c
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/*
* QNX4 file system, Linux implementation.
*
* Version : 0.2.1
*
* Using parts of the xiafs filesystem.
*
* History :
*
* 28-05-1998 by Richard Frowijn : first release.
* 20-06-1998 by Frank Denis : basic optimisations.
* 25-06-1998 by Frank Denis : qnx4_is_free, qnx4_set_bitmap, qnx4_bmap .
* 28-06-1998 by Frank Denis : qnx4_free_inode (to be fixed) .
*/
#include <linux/buffer_head.h>
#include <linux/bitops.h>
#include "qnx4.h"
unsigned long qnx4_count_free_blocks(struct super_block *sb)
{
int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
int total = 0;
int total_free = 0;
int offset = 0;
int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
struct buffer_head *bh;
while (total < size) {
int bytes = min(size - total, QNX4_BLOCK_SIZE);
if ((bh = sb_bread(sb, start + offset)) == NULL) {
printk(KERN_ERR "qnx4: I/O error in counting free blocks\n");
break;
}
total_free += bytes * BITS_PER_BYTE -
memweight(bh->b_data, bytes);
brelse(bh);
total += bytes;
offset++;
}
return total_free;
}