patch-2.3.14 linux/fs/partitions/msdos.c

• Lines: 495
• Date: Thu Aug 12 12:26:06 1999
• Orig file: v2.3.13/linux/fs/partitions/msdos.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.13/linux/fs/partitions/msdos.c linux/fs/partitions/msdos.c
@@ -0,0 +1,494 @@
+/*
+ *  fs/partitions/msdos.c
+ *
+ *  Code extracted from drivers/block/genhd.c
+ *  Copyright (C) 1991-1998  Linus Torvalds
+ *
+ *  Thanks to Branko Lankester, lankeste@fwi.uva.nl, who found a bug
+ *  in the early extended-partition checks and added DM partitions
+ *
+ *  Support for DiskManager v6.0x added by Mark Lord,
+ *  with information provided by OnTrack.  This now works for linux fdisk
+ *  and LILO, as well as loadlin and bootln.  Note that disks other than
+ *  /dev/hda *must* have a "DOS" type 0x51 partition in the first slot (hda1).
+ *
+ *  More flexible handling of extended partitions - aeb, 950831
+ *
+ *  Check partition table on IDE disks for common CHS translations
+ *
+ *  Re-organised Feb 1998 Russell King
+ */
+
+#include <linux/config.h>
+#include <linux/fs.h>
+#include <linux/genhd.h>
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/string.h>
+#include <linux/blk.h>
+
+#include <asm/system.h>
+
+#include "check.h"
+#include "msdos.h"
+
+static int current_minor;
+
+/*
+ * Many architectures don't like unaligned accesses, which is
+ * frequently the case with the nr_sects and start_sect partition
+ * table entries.
+ */
+#include <asm/unaligned.h>
+
+#define SYS_IND(p)	(get_unaligned(&p->sys_ind))
+#define NR_SECTS(p)	({ __typeof__(p->nr_sects) __a =	\
+				get_unaligned(&p->nr_sects);	\
+				le32_to_cpu(__a); \
+			})
+
+#define START_SECT(p)	({ __typeof__(p->start_sect) __a =	\
+				get_unaligned(&p->start_sect);	\
+				le32_to_cpu(__a); \
+			})
+
+static inline int is_extended_partition(struct partition *p)
+{
+	return (SYS_IND(p) == DOS_EXTENDED_PARTITION ||
+		SYS_IND(p) == WIN98_EXTENDED_PARTITION ||
+		SYS_IND(p) == LINUX_EXTENDED_PARTITION);
+}
+
+/*
+ * Create devices for each logical partition in an extended partition.
+ * The logical partitions form a linked list, with each entry being
+ * a partition table with two entries.  The first entry
+ * is the real data partition (with a start relative to the partition
+ * table start).  The second is a pointer to the next logical partition
+ * (with a start relative to the entire extended partition).
+ * We do not create a Linux partition for the partition tables, but
+ * only for the actual data partitions.
+ */
+
+static void extended_partition(struct gendisk *hd, kdev_t dev)
+{
+	struct buffer_head *bh;
+	struct partition *p;
+	unsigned long first_sector, first_size, this_sector, this_size;
+	int mask = (1 << hd->minor_shift) - 1;
+	int sector_size = get_hardsect_size(dev) / 512;
+	int i;
+
+	first_sector = hd->part[MINOR(dev)].start_sect;
+	first_size = hd->part[MINOR(dev)].nr_sects;
+	this_sector = first_sector;
+
+	while (1) {
+		if ((current_minor & mask) == 0)
+			return;
+		if (!(bh = bread(dev,0,get_ptable_blocksize(dev))))
+			return;
+
+		if ((*(__u16 *) (bh->b_data+510)) != cpu_to_le16(MSDOS_LABEL_MAGIC))
+			goto done;
+
+		p = (struct partition *) (0x1BE + bh->b_data);
+
+		this_size = hd->part[MINOR(dev)].nr_sects;
+
+		/*
+		 * Usually, the first entry is the real data partition,
+		 * the 2nd entry is the next extended partition, or empty,
+		 * and the 3rd and 4th entries are unused.
+		 * However, DRDOS sometimes has the extended partition as
+		 * the first entry (when the data partition is empty),
+		 * and OS/2 seems to use all four entries.
+		 */
+
+		/* 
+		 * First process the data partition(s)
+		 */
+		for (i=0; i<4; i++, p++) {
+			if (!NR_SECTS(p) || is_extended_partition(p))
+				continue;
+
+			/* Check the 3rd and 4th entries -
+			   these sometimes contain random garbage */
+			if (i >= 2
+				&& START_SECT(p) + NR_SECTS(p) > this_size
+				&& (this_sector + START_SECT(p) < first_sector ||
+				    this_sector + START_SECT(p) + NR_SECTS(p) >
+				     first_sector + first_size))
+				continue;
+
+			add_gd_partition(hd, current_minor, this_sector+START_SECT(p)*sector_size, NR_SECTS(p)*sector_size);
+			current_minor++;
+			if ((current_minor & mask) == 0)
+				goto done;
+		}
+		/*
+		 * Next, process the (first) extended partition, if present.
+		 * (So far, there seems to be no reason to make
+		 *  extended_partition()  recursive and allow a tree
+		 *  of extended partitions.)
+		 * It should be a link to the next logical partition.
+		 * Create a minor for this just long enough to get the next
+		 * partition table.  The minor will be reused for the next
+		 * data partition.
+		 */
+		p -= 4;
+		for (i=0; i<4; i++, p++)
+			if(NR_SECTS(p) && is_extended_partition(p))
+				break;
+		if (i == 4)
+			goto done;	 /* nothing left to do */
+
+		hd->part[current_minor].nr_sects = NR_SECTS(p) * sector_size; /* JSt */
+		hd->part[current_minor].start_sect = first_sector + START_SECT(p) * sector_size;
+		this_sector = first_sector + START_SECT(p) * sector_size;
+		dev = MKDEV(hd->major, current_minor);
+
+		/* Use bforget(), as we have changed the disk geometry */
+		bforget(bh);
+	}
+done:
+	bforget(bh);
+}
+
+#ifdef CONFIG_SOLARIS_X86_PARTITION
+static void
+solaris_x86_partition(struct gendisk *hd, kdev_t dev, long offset) {
+
+	struct buffer_head *bh;
+	struct solaris_x86_vtoc *v;
+	struct solaris_x86_slice *s;
+	int i;
+
+	if(!(bh = bread(dev, 0, get_ptable_blocksize(dev))))
+		return;
+	v = (struct solaris_x86_vtoc *)(bh->b_data + 512);
+	if(v->v_sanity != SOLARIS_X86_VTOC_SANE) {
+		brelse(bh);
+		return;
+	}
+	printk(" <solaris:");
+	if(v->v_version != 1) {
+		printk("  cannot handle version %ld vtoc>", v->v_version);
+		brelse(bh);
+		return;
+	}
+	for(i=0; i<SOLARIS_X86_NUMSLICE; i++) {
+		s = &v->v_slice[i];
+
+		if (s->s_size == 0)
+			continue;
+		printk(" [s%d]", i);
+		/* solaris partitions are relative to current MS-DOS
+		 * one but add_gd_partition starts relative to sector
+		 * zero of the disk.  Therefore, must add the offset
+		 * of the current partition */
+		add_gd_partition(hd, current_minor, s->s_start+offset, s->s_size);
+		current_minor++;
+	}
+	brelse(bh);
+	printk(" >");
+}
+#endif
+
+#ifdef CONFIG_BSD_DISKLABEL
+static void check_and_add_bsd_partition(struct gendisk *hd,
+					struct bsd_partition *bsd_p, kdev_t dev)
+{
+	struct hd_struct *lin_p;
+		/* check relative position of partitions.  */
+	for (lin_p = hd->part + 1 + MINOR(dev);
+	     lin_p - hd->part - MINOR(dev) < current_minor; lin_p++) {
+			/* no relationship -> try again */
+		if (lin_p->start_sect + lin_p->nr_sects <= bsd_p->p_offset 
+			|| lin_p->start_sect >= bsd_p->p_offset + bsd_p->p_size)
+			continue;	
+			/* equal -> no need to add */
+		if (lin_p->start_sect == bsd_p->p_offset && 
+			lin_p->nr_sects == bsd_p->p_size) 
+			return;
+			/* bsd living within dos partition */
+		if (lin_p->start_sect <= bsd_p->p_offset && lin_p->start_sect 
+			+ lin_p->nr_sects >= bsd_p->p_offset + bsd_p->p_size) {
+#ifdef DEBUG_BSD_DISKLABEL
+			printk("w: %d %ld+%ld,%d+%d", 
+				lin_p - hd->part, 
+				lin_p->start_sect, lin_p->nr_sects, 
+				bsd_p->p_offset, bsd_p->p_size);
+#endif
+			break;
+		}
+	 /* ouch: bsd and linux overlap. Don't even try for that partition */
+#ifdef DEBUG_BSD_DISKLABEL
+		printk("???: %d %ld+%ld,%d+%d",
+			lin_p - hd->part, lin_p->start_sect, lin_p->nr_sects,
+			bsd_p->p_offset, bsd_p->p_size);
+#endif
+		printk("???");
+		return;
+	} /* if the bsd partition is not currently known to linux, we end
+	   * up here 
+	   */
+	add_gd_partition(hd, current_minor, bsd_p->p_offset, bsd_p->p_size);
+	current_minor++;
+}
+/* 
+ * Create devices for BSD partitions listed in a disklabel, under a
+ * dos-like partition. See extended_partition() for more information.
+ */
+static void bsd_disklabel_partition(struct gendisk *hd, kdev_t dev, 
+   int max_partitions)
+{
+	struct buffer_head *bh;
+	struct bsd_disklabel *l;
+	struct bsd_partition *p;
+	int mask = (1 << hd->minor_shift) - 1;
+
+	if (!(bh = bread(dev,0,get_ptable_blocksize(dev))))
+		return;
+	l = (struct bsd_disklabel *) (bh->b_data+512);
+	if (l->d_magic != BSD_DISKMAGIC) {
+		brelse(bh);
+		return;
+	}
+
+	if (l->d_npartitions < max_partitions)
+		max_partitions = l->d_npartitions;
+	for (p = l->d_partitions; p - l->d_partitions <  max_partitions; p++) {
+		if ((current_minor & mask) >= (4 + hd->max_p))
+			break;
+
+		if (p->p_fstype != BSD_FS_UNUSED) 
+			check_and_add_bsd_partition(hd, p, dev);
+	}
+
+	/* Use bforget(), as we have changed the disk setup */
+	bforget(bh);
+
+}
+#endif
+
+#ifdef CONFIG_UNIXWARE_DISKLABEL
+/*
+ * 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, kdev_t dev)
+{
+	struct buffer_head *bh;
+	struct unixware_disklabel *l;
+	struct unixware_slice *p;
+	int mask = (1 << hd->minor_shift) - 1;
+
+	if (!(bh = bread(dev, 14, get_ptable_blocksize(dev))))
+		return;
+	l = (struct unixware_disklabel *) (bh->b_data+512);
+	if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
+	    le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
+		brelse(bh);
+		return;
+	}
+	printk(" <unixware:");
+	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++;
+	}
+	/* Use bforget, as we have changed the disk setup */
+	bforget(bh);
+	printk(" >");
+}
+#endif
+
+int msdos_partition(struct gendisk *hd, kdev_t dev, unsigned long first_sector, int first_part_minor)
+{
+	int i, minor = current_minor = first_part_minor;
+	struct buffer_head *bh;
+	struct partition *p;
+	unsigned char *data;
+	int mask = (1 << hd->minor_shift) - 1;
+	int sector_size = get_hardsect_size(dev) / 512;
+#ifdef CONFIG_BSD_DISKLABEL
+	/* no bsd disklabel as a default */
+	kdev_t bsd_kdev = 0;
+	int bsd_maxpart = BSD_MAXPARTITIONS;
+#endif
+#ifdef CONFIG_BLK_DEV_IDE
+	int tested_for_xlate = 0;
+
+read_mbr:
+#endif
+	if (!(bh = bread(dev,0,get_ptable_blocksize(dev)))) {
+		printk(" unable to read partition table\n");
+		return -1;
+	}
+	data = bh->b_data;
+#ifdef CONFIG_BLK_DEV_IDE
+check_table:
+#endif
+	/* Use bforget(), because we have potentially changed the disk geometry */
+	if (*(unsigned short *)  (0x1fe + data) != cpu_to_le16(MSDOS_LABEL_MAGIC)) {
+		bforget(bh);
+		return 0;
+	}
+	p = (struct partition *) (0x1be + data);
+
+#ifdef CONFIG_BLK_DEV_IDE
+	if (!tested_for_xlate++) {	/* Do this only once per disk */
+		/*
+		 * Look for various forms of IDE disk geometry translation
+		 */
+		extern int ide_xlate_1024(kdev_t, int, const char *);
+		unsigned int sig = le16_to_cpu(*(unsigned short *)(data + 2));
+		if (SYS_IND(p) == EZD_PARTITION) {
+			/*
+			 * The remainder of the disk must be accessed using
+			 * a translated geometry that reduces the number of 
+			 * apparent cylinders to less than 1024 if possible.
+			 *
+			 * ide_xlate_1024() will take care of the necessary
+			 * adjustments to fool fdisk/LILO and partition check.
+			 */
+			if (ide_xlate_1024(dev, -1, " [EZD]")) {
+				data += 512;
+				goto check_table;
+			}
+		} 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,
+			 * and the remainder of the disk must be accessed using
+			 * a translated geometry that reduces the number of 
+			 * apparent cylinders to less than 1024 if possible.
+			 *
+			 * ide_xlate_1024() will take care of the necessary
+			 * adjustments to fool fdisk/LILO and partition check.
+			 */
+			if (ide_xlate_1024(dev, 1, " [DM6:DDO]")) {
+				bforget(bh);
+				goto read_mbr;	/* start over with new MBR */
+			}
+		} else if (sig <= 0x1ae &&
+			   *(unsigned short *)(data + sig) == cpu_to_le16(0x55AA) &&
+			   (1 & *(unsigned char *)(data + sig + 2))) {
+			/* DM6 signature in MBR, courtesy of OnTrack */
+			(void) ide_xlate_1024 (dev, 0, " [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, " [DM6:AUX]");
+		} else {
+			/*
+			 * Examine the partition table for common translations.
+			 * This is useful for drives in situations where the
+			 * translated geometry is unavailable from the BIOS.
+			 */
+			for (i = 0; i < 4; i++) {
+				struct partition *q = &p[i];
+				if (NR_SECTS(q)
+				   && (q->sector & 63) == 1
+				   && (q->end_sector & 63) == 63) {
+					unsigned int heads = q->end_head + 1;
+					if (heads == 32 || heads == 64 ||
+					    heads == 128 || heads == 240 ||
+					    heads == 255) {
+						(void) ide_xlate_1024(dev, heads, " [PTBL]");
+						break;
+					}
+				}
+			}
+		}
+	}
+#endif	/* CONFIG_BLK_DEV_IDE */
+
+	current_minor += 4;  /* first "extra" minor (for extended partitions) */
+	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 (is_extended_partition(p)) {
+			printk(" <");
+			/*
+			 * If we are rereading the partition table, we need
+			 * to set the size of the partition so that we will
+			 * be able to bread the block containing the extended
+			 * partition info.
+			 */
+			hd->sizes[minor] = hd->part[minor].nr_sects 
+			  	>> (BLOCK_SIZE_BITS - 9);
+			extended_partition(hd, MKDEV(hd->major, minor));
+			printk(" >");
+			/* prevent someone doing mkfs or mkswap on an
+			   extended partition, but leave room for LILO */
+			if (hd->part[minor].nr_sects > 2)
+				hd->part[minor].nr_sects = 2;
+		}
+#ifdef CONFIG_BSD_DISKLABEL
+			/* tag first disklabel for late recognition */
+		if (SYS_IND(p) == BSD_PARTITION || SYS_IND(p) == NETBSD_PARTITION) {
+			printk("!");
+			if (!bsd_kdev)
+				bsd_kdev = MKDEV(hd->major, minor);
+		} else if (SYS_IND(p) == OPENBSD_PARTITION) {
+			printk("!");
+			if (!bsd_kdev) {
+				bsd_kdev = MKDEV(hd->major, minor);
+				bsd_maxpart = OPENBSD_MAXPARTITIONS;
+			}
+		}
+#endif
+#ifdef CONFIG_UNIXWARE_DISKLABEL
+		if (SYS_IND(p) == UNIXWARE_PARTITION)
+			unixware_partition(hd, MKDEV(hd->major, minor));
+#endif
+#ifdef CONFIG_SOLARIS_X86_PARTITION
+
+		/* james@bpgc.com: Solaris has a nasty indicator: 0x82
+		 * which also means linux swap.  For that reason, all
+		 * of the prints are done inside the
+		 * solaris_x86_partition routine */
+
+		if(SYS_IND(p) == SOLARIS_X86_PARTITION) {
+			solaris_x86_partition(hd, MKDEV(hd->major, minor),
+					      first_sector+START_SECT(p));
+		}
+#endif
+	}
+#ifdef CONFIG_BSD_DISKLABEL
+	if (bsd_kdev) {
+		printk(" <");
+		bsd_disklabel_partition(hd, bsd_kdev, bsd_maxpart);
+		printk(" >");
+	}
+#endif
+	/*
+	 *  Check for old-style Disk Manager partition table
+	 */
+	if (*(unsigned short *) (data+0xfc) == cpu_to_le16(MSDOS_LABEL_MAGIC)) {
+		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");
+	bforget(bh);
+	return 1;
+}