msdos.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

		return;
	if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) {
		put_dev_sector(sect);
		return;
	}
	printk(" %s: <%s:", partition_name(hd, minor, buf), name);

	if (le16_to_cpu(l->d_npartitions) < max_partitions)
		max_partitions = le16_to_cpu(l->d_npartitions);
	for (p = l->d_partitions; p - l->d_partitions <  max_partitions; p++) {
		if ((*current_minor & mask) == 0)
			break;
		if (p->p_fstype == BSD_FS_UNUSED) 
			continue;
		check_and_add_bsd_partition(hd, p, baseminor, current_minor);
	}
	put_dev_sector(sect);
	printk(" >\n");
}
#endif

static void bsd_partition(struct gendisk *hd, struct block_device *bdev,
	int minor, int *current_minor)
{
#ifdef CONFIG_BSD_DISKLABEL
	do_bsd_partition(hd, bdev, minor, current_minor, "bsd",
		BSD_MAXPARTITIONS);
#endif
}

static void netbsd_partition(struct gendisk *hd, struct block_device *bdev,
		int minor, int *current_minor)
{
#ifdef CONFIG_BSD_DISKLABEL
	do_bsd_partition(hd, bdev, minor, current_minor, "netbsd",
			BSD_MAXPARTITIONS);
#endif
}

static void openbsd_partition(struct gendisk *hd, struct block_device *bdev,
		int minor, int *current_minor)
{
#ifdef CONFIG_BSD_DISKLABEL
	do_bsd_partition(hd, bdev, minor, current_minor,
			"openbsd", OPENBSD_MAXPARTITIONS);
#endif
}

/*
 * Create devices for Unixware partitions listed in a disklabel, under a
 * dos-like partition. See extended_partition() for more information.
 */
static void unixware_partition(struct gendisk *hd, struct block_device *bdev,
		int minor, int *current_minor)
{
#ifdef CONFIG_UNIXWARE_DISKLABEL
	long offset = hd->part[minor].start_sect;
	Sector sect;
	struct unixware_disklabel *l;
	struct unixware_slice *p;
	int mask = (1 << hd->minor_shift) - 1;
	char buf[40];

	l = (struct unixware_disklabel *)read_dev_sector(bdev, offset+29, &sect);
	if (!l)
		return;
	if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
	    le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
		put_dev_sector(sect);
		return;
	}
	printk(" %s: <unixware:", partition_name(hd, minor, buf));
	p = &l->vtoc.v_slice[1];
	/* I omit the 0th slice as it is the same as whole disk. */
	while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
		if ((*current_minor & mask) == 0)
			break;

		if (p->s_label != UNIXWARE_FS_UNUSED) {
			add_gd_partition(hd, *current_minor, START_SECT(p),
					 NR_SECTS(p));
			(*current_minor)++;
		}
		p++;
	}
	put_dev_sector(sect);
	printk(" >\n");
#endif
}

/*
 * Minix 2.0.0/2.0.2 subpartition support.
 * Anand Krishnamurthy <[e-mail]>
 * Rajeev V. Pillai    <[e-mail]>
 */
static void minix_partition(struct gendisk *hd, struct block_device *bdev,
		int minor, int *current_minor)
{
#ifdef CONFIG_MINIX_SUBPARTITION
	long offset = hd->part[minor].start_sect;
	Sector sect;
	unsigned char *data;
	struct partition *p;
	int mask = (1 << hd->minor_shift) - 1;
	int i;
	char buf[40];

	data = read_dev_sector(bdev, offset, &sect);
	if (!data)
		return;

	p = (struct partition *)(data + 0x1be);

	/* The first sector of a Minix partition can have either
	 * a secondary MBR describing its subpartitions, or
	 * the normal boot sector. */
	if (msdos_magic_present (data + 510) &&
	    SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */

		printk(" %s: <minix:", partition_name(hd, minor, buf));
		for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
			if ((*current_minor & mask) == 0)
				break;
			/* add each partition in use */
			if (SYS_IND(p) == MINIX_PARTITION) {
				add_gd_partition(hd, *current_minor,
					      START_SECT(p), NR_SECTS(p));
				(*current_minor)++;
			}
		}
		printk(" >\n");
	}
	put_dev_sector(sect);
#endif /* CONFIG_MINIX_SUBPARTITION */
}

static struct {
	unsigned char id;
	void (*parse)(struct gendisk *, struct block_device *, int, int *);
} subtypes[] = {
	{BSD_PARTITION, bsd_partition},
	{NETBSD_PARTITION, netbsd_partition},
	{OPENBSD_PARTITION, openbsd_partition},
	{MINIX_PARTITION, minix_partition},
	{UNIXWARE_PARTITION, unixware_partition},
	{SOLARIS_X86_PARTITION, solaris_x86_partition},
	{0, NULL},
};
/*
 * Look for various forms of IDE disk geometry translation
 */
static int handle_ide_mess(struct block_device *bdev)
{
#ifdef CONFIG_BLK_DEV_IDE
	Sector sect;
	unsigned char *data;
	kdev_t dev = to_kdev_t(bdev->bd_dev);
	unsigned int sig;
	int heads = 0;
	struct partition *p;
	int i;
	/*
	 * The i386 partition handling programs very often
	 * make partitions end on cylinder boundaries.
	 * There is no need to do so, and Linux fdisk doesnt always
	 * do this, and Windows NT on Alpha doesnt do this either,
	 * but still, this helps to guess #heads.
	 */
	data = read_dev_sector(bdev, 0, &sect);
	if (!data)
		return -1;
	if (!msdos_magic_present(data + 510)) {
		put_dev_sector(sect);
		return 0;
	}
	sig = le16_to_cpu(*(unsigned short *)(data + 2));
	p = (struct partition *) (data + 0x1be);
	for (i = 0; i < 4; i++) {
		struct partition *q = &p[i];
		if (NR_SECTS(q)) {
			if ((q->sector & 63) == 1 &&
			    (q->end_sector & 63) == 63)
				heads = q->end_head + 1;
			break;
		}
	}
	if (SYS_IND(p) == EZD_PARTITION) {
		/*
		 * Accesses to sector 0 must go to sector 1 instead.
		 */
		if (ide_xlate_1024(dev, -1, heads, " [EZD]"))
			goto reread;
	} else if (SYS_IND(p) == DM6_PARTITION) {

		/*
		 * Everything on the disk is offset by 63 sectors,
		 * including a "new" MBR with its own partition table.
		 */
		if (ide_xlate_1024(dev, 1, heads, " [DM6:DDO]"))
			goto reread;
	} else if (sig <= 0x1ae &&
		   data[sig] == 0xAA && data[sig+1] == 0x55 &&
		   (data[sig+2] & 1)) {
		/* DM6 signature in MBR, courtesy of OnTrack */
		(void) ide_xlate_1024 (dev, 0, heads, " [DM6:MBR]");
	} else if (SYS_IND(p) == DM6_AUX1PARTITION ||
		   SYS_IND(p) == DM6_AUX3PARTITION) {
		/*
		 * DM6 on other than the first (boot) drive
		 */
		(void) ide_xlate_1024(dev, 0, heads, " [DM6:AUX]");
	} else {
		(void) ide_xlate_1024(dev, 2, heads, " [PTBL]");
	}
	put_dev_sector(sect);
	return 1;

reread:
	put_dev_sector(sect);
	/* Flush the cache */
	invalidate_bdev(bdev, 1);
	truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
#endif /* CONFIG_BLK_DEV_IDE */
	return 1;
}
 
int msdos_partition(struct gendisk *hd, struct block_device *bdev,
		    unsigned long first_sector, int first_part_minor)
{
	int i, minor = first_part_minor;
	Sector sect;
	struct partition *p;
	unsigned char *data;
	int mask = (1 << hd->minor_shift) - 1;
	int sector_size = get_hardsect_size(to_kdev_t(bdev->bd_dev)) / 512;
	int current_minor = first_part_minor;
	int err;

	err = handle_ide_mess(bdev);
	if (err <= 0)
		return err;
	data = read_dev_sector(bdev, 0, &sect);
	if (!data)
		return -1;
	if (!msdos_magic_present(data + 510)) {
		put_dev_sector(sect);
		return 0;
	}
	p = (struct partition *) (data + 0x1be);

	/*
	 * Look for partitions in two passes:
	 * First find the primary and DOS-type extended partitions.
	 * On the second pass look inside *BSD, Unixware and Solaris partitions.
	 */

	current_minor += 4;
	for (i=1 ; i<=4 ; minor++,i++,p++) {
		if (!NR_SECTS(p))
			continue;
		add_gd_partition(hd, minor,
				first_sector+START_SECT(p)*sector_size,
				NR_SECTS(p)*sector_size);
#if CONFIG_BLK_DEV_MD
		if (SYS_IND(p) == LINUX_RAID_PARTITION) {
			md_autodetect_dev(MKDEV(hd->major,minor));
		}
#endif
		if (is_extended_partition(p)) {
			unsigned long size = hd->part[minor].nr_sects;
			printk(" <");
			/* prevent someone doing mkfs or mkswap on an
			   extended partition, but leave room for LILO */
			if (size > 2)
				hd->part[minor].nr_sects = 2;
			extended_partition(hd, bdev, minor, size, &current_minor);
			printk(" >");
		}
	}

	/*
	 *  Check for old-style Disk Manager partition table
	 */
	if (msdos_magic_present(data + 0xfc)) {
		p = (struct partition *) (0x1be + data);
		for (i = 4 ; i < 16 ; i++, current_minor++) {
			p--;
			if ((current_minor & mask) == 0)
				break;
			if (!(START_SECT(p) && NR_SECTS(p)))
				continue;
			add_gd_partition(hd, current_minor, START_SECT(p), NR_SECTS(p));
		}
	}
	printk("\n");

	/* second pass - output for each on a separate line */
	minor -= 4;
	p = (struct partition *) (0x1be + data);
	for (i=1 ; i<=4 ; minor++,i++,p++) {
		unsigned char id = SYS_IND(p);
		int n;

		if (!NR_SECTS(p))
			continue;

		for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++)
			;

		if (subtypes[n].parse)
			subtypes[n].parse(hd, bdev, minor, &current_minor);
	}
	put_dev_sector(sect);
	return 1;
}