[PARTITION]: Sun/Solaris VTOC table corrections

Start doing VTOC validation before using its contents.
The validation is adjusted so as not to break existing setups
that do not set the VTOC version, sanity and partition count entries.
VTOC tables with more than 8 partitions will NOT be used.
Signed-off-by: Mark Fortescue <mark@mtfhpc.demon.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

fs/partitions/sun.c

@@ -19,34 +19,47 @@ int sun_partition(struct parsed_partitions *state, struct block_device *bdev)
 	Sector sect;
 	struct sun_disklabel {
 		unsigned char info[128];   /* Informative text string */
-		unsigned char spare0[14];
-		struct sun_info {
-			unsigned char spare1;
-			unsigned char id;
-			unsigned char spare2;
-			unsigned char flags;
-		} infos[8];
-		unsigned char spare[246];  /* Boot information etc. */
+		struct sun_vtoc {
+		    __be32 version;     /* Layout version */
+		    char   volume[8];   /* Volume name */
+		    __be16 nparts;      /* Number of partitions */
+		    struct sun_info {           /* Partition hdrs, sec 2 */
+			__be16 id;
+			__be16 flags;
+		    } infos[8];
+		    __be16 padding;     /* Alignment padding */
+		    __be32 bootinfo[3];  /* Info needed by mboot */
+		    __be32 sanity;       /* To verify vtoc sanity */
+		    __be32 reserved[10]; /* Free space */
+		    __be32 timestamp[8]; /* Partition timestamp */
+		} vtoc;
+		__be32 write_reinstruct; /* sectors to skip, writes */
+		__be32 read_reinstruct;  /* sectors to skip, reads */
+		unsigned char spare[148]; /* Padding */
 		__be16 rspeed;     /* Disk rotational speed */
 		__be16 pcylcount;  /* Physical cylinder count */
 		__be16 sparecyl;   /* extra sects per cylinder */
-		unsigned char spare2[4];   /* More magic... */
+		__be16 obs1;       /* gap1 */
+		__be16 obs2;       /* gap2 */
 		__be16 ilfact;     /* Interleave factor */
 		__be16 ncyl;       /* Data cylinder count */
 		__be16 nacyl;      /* Alt. cylinder count */
 		__be16 ntrks;      /* Tracks per cylinder */
 		__be16 nsect;      /* Sectors per track */
-		unsigned char spare3[4];   /* Even more magic... */
+		__be16 obs3;       /* bhead - Label head offset */
+		__be16 obs4;       /* ppart - Physical Partition */
 		struct sun_partition {
 			__be32 start_cylinder;
 			__be32 num_sectors;
 		} partitions[8];
 		__be16 magic;      /* Magic number */
 		__be16 csum;       /* Label xor'd checksum */
-	} * label;		
+	} * label;
 	struct sun_partition *p;
 	unsigned long spc;
 	char b[BDEVNAME_SIZE];
+	int use_vtoc;
+	int nparts;
 
 	label = (struct sun_disklabel *)read_dev_sector(bdev, 0, &sect);
 	if (!label)
@@ -70,9 +83,22 @@ int sun_partition(struct parsed_partitions *state, struct block_device *bdev)
 		return 0;
 	}
 
-	/* All Sun disks have 8 partition entries */
+	/* Check to see if we can use the VTOC table */
+	use_vtoc = ((be32_to_cpu(label->vtoc.sanity) == SUN_VTOC_SANITY) &&
+		    (be32_to_cpu(label->vtoc.version) == 1) &&
+		    (be16_to_cpu(label->vtoc.nparts) <= 8));
+
+	/* Use 8 partition entries if not specified in validated VTOC */
+	nparts = (use_vtoc) ? be16_to_cpu(label->vtoc.nparts) : 8;
+
+	/*
+	 * So that old Linux-Sun partitions continue to work,
+	 * alow the VTOC to be used under the additional condition ...
+	 */
+	use_vtoc = use_vtoc || !(label->vtoc.sanity |
+				 label->vtoc.version | label->vtoc.nparts);
 	spc = be16_to_cpu(label->ntrks) * be16_to_cpu(label->nsect);
-	for (i = 0; i < 8; i++, p++) {
+	for (i = 0; i < nparts; i++, p++) {
 		unsigned long st_sector;
 		unsigned int num_sectors;
 
@@ -81,10 +107,12 @@ int sun_partition(struct parsed_partitions *state, struct block_device *bdev)
 		if (num_sectors) {
 			put_partition(state, slot, st_sector, num_sectors);
 			state->parts[slot].flags = 0;
-			if (label->infos[i].id == LINUX_RAID_PARTITION)
-				state->parts[slot].flags |= ADDPART_FLAG_RAID;
-			if (label->infos[i].id == SUN_WHOLE_DISK)
-				state->parts[slot].flags |= ADDPART_FLAG_WHOLEDISK;
+			if (use_vtoc) {
+				if (be16_to_cpu(label->vtoc.infos[i].id) == LINUX_RAID_PARTITION)
+					state->parts[slot].flags |= ADDPART_FLAG_RAID;
+				else if (be16_to_cpu(label->vtoc.infos[i].id) == SUN_WHOLE_DISK)
+					state->parts[slot].flags |= ADDPART_FLAG_WHOLEDISK;
+			}
 		}
 		slot++;
 	}

fs/partitions/sun.h

@@ -3,5 +3,6 @@
  */
 
 #define SUN_LABEL_MAGIC          0xDABE
+#define SUN_VTOC_SANITY          0x600DDEEE
 
 int sun_partition(struct parsed_partitions *state, struct block_device *bdev);