root/fs/qnx4/bitmap.c

DEFINITIONS

1. qnx4_new_block
2. count_bits
3. qnx4_count_free_blocks
4. qnx4_is_free
5. qnx4_set_bitmap
6. qnx4_clear_inode
7. qnx4_free_inode

/*
 * 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/time.h>
#include <linux/fs.h>
#include <linux/qnx4_fs.h>
#include <linux/stat.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/bitops.h>

#if 0
int qnx4_new_block(struct super_block *sb)
{
        return 0;
}
#endif  /*  0  */

static void count_bits(register const char *bmPart, register int size,
                       int *const tf)
{
        char b;
        int tot = *tf;

        if (size > QNX4_BLOCK_SIZE) {
                size = QNX4_BLOCK_SIZE;
        }
        do {
                b = *bmPart++;
                if ((b & 1) == 0)
                        tot++;
                if ((b & 2) == 0)
                        tot++;
                if ((b & 4) == 0)
                        tot++;
                if ((b & 8) == 0)
                        tot++;
                if ((b & 16) == 0)
                        tot++;
                if ((b & 32) == 0)
                        tot++;
                if ((b & 64) == 0)
                        tot++;
                if ((b & 128) == 0)
                        tot++;
                size--;
        } while (size != 0);
        *tf = tot;
}

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) {
                if ((bh = sb_bread(sb, start + offset)) == NULL) {
                        printk("qnx4: I/O error in counting free blocks\n");
                        break;
                }
                count_bits(bh->b_data, size - total, &total_free);
                brelse(bh);
                total += QNX4_BLOCK_SIZE;
                offset++;
        }

        return total_free;
}

#ifdef CONFIG_QNX4FS_RW

int qnx4_is_free(struct super_block *sb, long block)
{
        int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
        int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
        struct buffer_head *bh;
        const char *g;
        int ret = -EIO;

        start += block / (QNX4_BLOCK_SIZE * 8);
        QNX4DEBUG(("qnx4: is_free requesting block [%lu], bitmap in block [%lu]\n",
                   (unsigned long) block, (unsigned long) start));
        (void) size;            /* CHECKME */
        bh = sb_bread(sb, start);
        if (bh == NULL) {
                return -EIO;
        }
        g = bh->b_data + (block % QNX4_BLOCK_SIZE);
        if (((*g) & (1 << (block % 8))) == 0) {
                QNX4DEBUG(("qnx4: is_free -> block is free\n"));
                ret = 1;
        } else {
                QNX4DEBUG(("qnx4: is_free -> block is busy\n"));
                ret = 0;
        }
        brelse(bh);

        return ret;
}

int qnx4_set_bitmap(struct super_block *sb, long block, int busy)
{
        int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
        int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
        struct buffer_head *bh;
        char *g;

        start += block / (QNX4_BLOCK_SIZE * 8);
        QNX4DEBUG(("qnx4: set_bitmap requesting block [%lu], bitmap in block [%lu]\n",
                   (unsigned long) block, (unsigned long) start));
        (void) size;            /* CHECKME */
        bh = sb_bread(sb, start);
        if (bh == NULL) {
                return -EIO;
        }
        g = bh->b_data + (block % QNX4_BLOCK_SIZE);
        if (busy == 0) {
                (*g) &= ~(1 << (block % 8));
        } else {
                (*g) |= (1 << (block % 8));
        }
        mark_buffer_dirty(bh);
        brelse(bh);

        return 0;
}

static void qnx4_clear_inode(struct inode *inode)
{
        struct qnx4_inode_entry *qnx4_ino = qnx4_raw_inode(inode);
        /* What for? */
        memset(qnx4_ino->di_fname, 0, sizeof qnx4_ino->di_fname);
        qnx4_ino->di_size = 0;
        qnx4_ino->di_num_xtnts = 0;
        qnx4_ino->di_mode = 0;
        qnx4_ino->di_status = 0;
}

void qnx4_free_inode(struct inode *inode)
{
        if (inode->i_ino < 1) {
                printk("free_inode: inode 0 or nonexistent inode\n");
                return;
        }
        qnx4_clear_inode(inode);
        clear_inode(inode);
}

#endif