linux/fs/qnx4/bitmap.c
Akinobu Mita 9b58f6d4aa qnx4fs: use memweight()
Use memweight() to count the total number of bits clear in memory area.

Note that this memweight() call can't be replaced with a single
bitmap_weight() call, although the pointer to the memory area is aligned
to long-word boundary.  Because the size of the memory area may not be a
multiple of BITS_PER_LONG, then it returns wrong value on big-endian
architecture.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Anders Larsen <al@alarsen.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-30 17:25:16 -07:00

45 lines
1.0 KiB
C

/*
* 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;
}