Skip to main content

Browse the archive

Revision fc9bbca8f650e5f738af8806317c0a041a48ae4a authored by Linus Torvalds on 19 April 2013, 16:57:35 UTC, committed by Linus Torvalds on 19 April 2013, 16:57:35 UTC 
vm: convert fb_mmap to vm_iomap_memory() helper
 
This is my example conversion of a few existing mmap users.  The
fb_mmap() case is a good example because it is a bit more complicated
than some: fb_mmap() mmaps one of two different memory areas depending
on the page offset of the mmap (but happily there is never any mixing of
the two, so the helper function still works).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 8558e4a
Raw File
bitmap.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;
}
back to top