FreeBSD/Linux Kernel Cross Reference
sys/fs/partitions/ldm.c

     /**
      * ldm - Support for Windows Logical Disk Manager (Dynamic Disks)
      *
      * Copyright (C) 2001,2002 Richard Russon <ldm@flatcap.org>
      * Copyright (C) 2001      Anton Altaparmakov <aia21@cantab.net>
      * Copyright (C) 2001,2002 Jakob Kemi <jakob.kemi@telia.com>
      *
      * Documentation is available at http://linux-ntfs.sf.net/ldm
      *
     * This program is free software; you can redistribute it and/or modify it under
     * the terms of the GNU General Public License as published by the Free Software
     * Foundation; either version 2 of the License, or (at your option) any later
     * version.
     *
     * This program is distributed in the hope that it will be useful, but WITHOUT
     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
     * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
     * details.
     *
     * You should have received a copy of the GNU General Public License along with
     * this program (in the main directory of the source in the file COPYING); if
     * not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
     * Boston, MA  02111-1307  USA
     */
    
    #include <linux/slab.h>
    #include <linux/stringify.h>
    #include <linux/pagemap.h>
    #include "ldm.h"
    #include "check.h"
    #include "msdos.h"
    
    typedef enum {
            FALSE = 0,
            TRUE  = 1
    } BOOL;
    
    /**
     * ldm_debug/info/error/crit - Output an error message
     * @f:    A printf format string containing the message
     * @...:  Variables to substitute into @f
     *
     * ldm_debug() writes a DEBUG level message to the syslog but only if the
     * driver was compiled with debug enabled. Otherwise, the call turns into a NOP.
     */
    #ifndef CONFIG_LDM_DEBUG
    #define ldm_debug(...)  do {} while (0)
    #else
    #define ldm_debug(f, a...) _ldm_printk (KERN_DEBUG, __FUNCTION__, f, ##a)
    #endif
    
    #define ldm_crit(f, a...)  _ldm_printk (KERN_CRIT,  __FUNCTION__, f, ##a)
    #define ldm_error(f, a...) _ldm_printk (KERN_ERR,   __FUNCTION__, f, ##a)
    #define ldm_info(f, a...)  _ldm_printk (KERN_INFO,  __FUNCTION__, f, ##a)
    
    __attribute__ ((format (printf, 3, 4)))
    static void _ldm_printk (const char *level, const char *function,
                             const char *fmt, ...)
    {
            static char buf[128];
            va_list args;
    
            va_start (args, fmt);
            vsnprintf (buf, sizeof (buf), fmt, args);
            va_end (args);
    
            printk ("%s%s(): %s\n", level, function, buf);
    }
    
    
    /**
     * ldm_parse_hexbyte - Convert a ASCII hex number to a byte
     * @src:  Pointer to at least 2 characters to convert.
     *
     * Convert a two character ASCII hex string to a number.
     *
     * Return:  0-255  Success, the byte was parsed correctly
     *          -1     Error, an invalid character was supplied
     */
    static int ldm_parse_hexbyte (const u8 *src)
    {
            unsigned int x;         /* For correct wrapping */
            int h;
    
            /* high part */
            if      ((x = src[0] - '') <= '9'-'') h = x;
            else if ((x = src[0] - 'a') <= 'f'-'a') h = x+10;
            else if ((x = src[0] - 'A') <= 'F'-'A') h = x+10;
            else return -1;
            h <<= 4;
    
            /* low part */
            if ((x = src[1] - '') <= '9'-'') return h | x;
            if ((x = src[1] - 'a') <= 'f'-'a') return h | (x+10);
            if ((x = src[1] - 'A') <= 'F'-'A') return h | (x+10);
            return -1;
    }
    
    /**
    * ldm_parse_guid - Convert GUID from ASCII to binary
    * @src:   36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
    * @dest:  Memory block to hold binary GUID (16 bytes)
    *
    * N.B. The GUID need not be NULL terminated.
    *
    * Return:  TRUE   @dest contains binary GUID
    *          FALSE  @dest contents are undefined
    */
   static BOOL ldm_parse_guid (const u8 *src, u8 *dest)
   {
           static const int size[] = { 4, 2, 2, 2, 6 };
           int i, j, v;
   
           if (src[8]  != '-' || src[13] != '-' ||
               src[18] != '-' || src[23] != '-')
                   return FALSE;
   
           for (j = 0; j < 5; j++, src++)
                   for (i = 0; i < size[j]; i++, src+=2, *dest++ = v)
                           if ((v = ldm_parse_hexbyte (src)) < 0)
                                   return FALSE;
   
           return TRUE;
   }
   
   
   /**
    * ldm_parse_privhead - Read the LDM Database PRIVHEAD structure
    * @data:  Raw database PRIVHEAD structure loaded from the device
    * @ph:    In-memory privhead structure in which to return parsed information
    *
    * This parses the LDM database PRIVHEAD structure supplied in @data and
    * sets up the in-memory privhead structure @ph with the obtained information.
    *
    * Return:  TRUE   @ph contains the PRIVHEAD data
    *          FALSE  @ph contents are undefined
    */
   static BOOL ldm_parse_privhead (const u8 *data, struct privhead *ph)
   {
           BUG_ON (!data);
           BUG_ON (!ph);
   
           if (MAGIC_PRIVHEAD != BE64 (data)) {
                   ldm_error ("Cannot find PRIVHEAD structure. LDM database is"
                           " corrupt. Aborting.");
                   return FALSE;
           }
   
           ph->ver_major          = BE16 (data + 0x000C);
           ph->ver_minor          = BE16 (data + 0x000E);
           ph->logical_disk_start = BE64 (data + 0x011B);
           ph->logical_disk_size  = BE64 (data + 0x0123);
           ph->config_start       = BE64 (data + 0x012B);
           ph->config_size        = BE64 (data + 0x0133);
   
           if ((ph->ver_major != 2) || (ph->ver_minor != 11)) {
                   ldm_error ("Expected PRIVHEAD version %d.%d, got %d.%d."
                           " Aborting.", 2, 11, ph->ver_major, ph->ver_minor);
                   return FALSE;
           }
           if (ph->config_size != LDM_DB_SIZE) {   /* 1 MiB in sectors. */
                   /* Warn the user and continue, carefully */
                   ldm_info ("Database is normally %u bytes, it claims to "
                           "be %llu bytes.", LDM_DB_SIZE,
                           (unsigned long long)ph->config_size );
           }
           if ((ph->logical_disk_size == 0) ||
               (ph->logical_disk_start + ph->logical_disk_size > ph->config_start)) {
                   ldm_error ("PRIVHEAD disk size doesn't match real disk size");
                   return FALSE;
           }
   
           if (!ldm_parse_guid (data + 0x0030, ph->disk_id)) {
                   ldm_error ("PRIVHEAD contains an invalid GUID.");
                   return FALSE;
           }
   
           ldm_debug ("Parsed PRIVHEAD successfully.");
           return TRUE;
   }
   
   /**
    * ldm_parse_tocblock - Read the LDM Database TOCBLOCK structure
    * @data:  Raw database TOCBLOCK structure loaded from the device
    * @toc:   In-memory toc structure in which to return parsed information
    *
    * This parses the LDM Database TOCBLOCK (table of contents) structure supplied
    * in @data and sets up the in-memory tocblock structure @toc with the obtained
    * information.
    *
    * N.B.  The *_start and *_size values returned in @toc are not range-checked.
    *
    * Return:  TRUE   @toc contains the TOCBLOCK data
    *          FALSE  @toc contents are undefined
    */
   static BOOL ldm_parse_tocblock (const u8 *data, struct tocblock *toc)
   {
           BUG_ON (!data);
           BUG_ON (!toc);
   
           if (MAGIC_TOCBLOCK != BE64 (data)) {
                   ldm_crit ("Cannot find TOCBLOCK, database may be corrupt.");
                   return FALSE;
           }
           strncpy (toc->bitmap1_name, data + 0x24, sizeof (toc->bitmap1_name));
           toc->bitmap1_name[sizeof (toc->bitmap1_name) - 1] = 0;
           toc->bitmap1_start = BE64 (data + 0x2E);
           toc->bitmap1_size  = BE64 (data + 0x36);
   
           if (strncmp (toc->bitmap1_name, TOC_BITMAP1,
                           sizeof (toc->bitmap1_name)) != 0) {
                   ldm_crit ("TOCBLOCK's first bitmap is '%s', should be '%s'.",
                                   TOC_BITMAP1, toc->bitmap1_name);
                   return FALSE;
           }
           strncpy (toc->bitmap2_name, data + 0x46, sizeof (toc->bitmap2_name));
           toc->bitmap2_name[sizeof (toc->bitmap2_name) - 1] = 0;
           toc->bitmap2_start = BE64 (data + 0x50);
           toc->bitmap2_size  = BE64 (data + 0x58);
           if (strncmp (toc->bitmap2_name, TOC_BITMAP2,
                           sizeof (toc->bitmap2_name)) != 0) {
                   ldm_crit ("TOCBLOCK's second bitmap is '%s', should be '%s'.",
                                   TOC_BITMAP2, toc->bitmap2_name);
                   return FALSE;
           }
           ldm_debug ("Parsed TOCBLOCK successfully.");
           return TRUE;
   }
   
   /**
    * ldm_parse_vmdb - Read the LDM Database VMDB structure
    * @data:  Raw database VMDB structure loaded from the device
    * @vm:    In-memory vmdb structure in which to return parsed information
    *
    * This parses the LDM Database VMDB structure supplied in @data and sets up
    * the in-memory vmdb structure @vm with the obtained information.
    *
    * N.B.  The *_start, *_size and *_seq values will be range-checked later.
    *
    * Return:  TRUE   @vm contains VMDB info
    *          FALSE  @vm contents are undefined
    */
   static BOOL ldm_parse_vmdb (const u8 *data, struct vmdb *vm)
   {
           BUG_ON (!data);
           BUG_ON (!vm);
   
           if (MAGIC_VMDB != BE32 (data)) {
                   ldm_crit ("Cannot find the VMDB, database may be corrupt.");
                   return FALSE;
           }
   
           vm->ver_major = BE16 (data + 0x12);
           vm->ver_minor = BE16 (data + 0x14);
           if ((vm->ver_major != 4) || (vm->ver_minor != 10)) {
                   ldm_error ("Expected VMDB version %d.%d, got %d.%d. "
                           "Aborting.", 4, 10, vm->ver_major, vm->ver_minor);
                   return FALSE;
           }
   
           vm->vblk_size     = BE32 (data + 0x08);
           vm->vblk_offset   = BE32 (data + 0x0C);
           vm->last_vblk_seq = BE32 (data + 0x04);
   
           ldm_debug ("Parsed VMDB successfully.");
           return TRUE;
   }
   
   /**
    * ldm_compare_privheads - Compare two privhead objects
    * @ph1:  First privhead
    * @ph2:  Second privhead
    *
    * This compares the two privhead structures @ph1 and @ph2.
    *
    * Return:  TRUE   Identical
    *          FALSE  Different
    */
   static BOOL ldm_compare_privheads (const struct privhead *ph1,
                                      const struct privhead *ph2)
   {
           BUG_ON (!ph1);
           BUG_ON (!ph2);
   
           return ((ph1->ver_major          == ph2->ver_major)             &&
                   (ph1->ver_minor          == ph2->ver_minor)             &&
                   (ph1->logical_disk_start == ph2->logical_disk_start)    &&
                   (ph1->logical_disk_size  == ph2->logical_disk_size)     &&
                   (ph1->config_start       == ph2->config_start)          &&
                   (ph1->config_size        == ph2->config_size)           &&
                   !memcmp (ph1->disk_id, ph2->disk_id, GUID_SIZE));
   }
   
   /**
    * ldm_compare_tocblocks - Compare two tocblock objects
    * @toc1:  First toc
    * @toc2:  Second toc
    *
    * This compares the two tocblock structures @toc1 and @toc2.
    *
    * Return:  TRUE   Identical
    *          FALSE  Different
    */
   static BOOL ldm_compare_tocblocks (const struct tocblock *toc1,
                                      const struct tocblock *toc2)
   {
           BUG_ON (!toc1);
           BUG_ON (!toc2);
   
           return ((toc1->bitmap1_start == toc2->bitmap1_start)    &&
                   (toc1->bitmap1_size  == toc2->bitmap1_size)     &&
                   (toc1->bitmap2_start == toc2->bitmap2_start)    &&
                   (toc1->bitmap2_size  == toc2->bitmap2_size)     &&
                   !strncmp (toc1->bitmap1_name, toc2->bitmap1_name,
                           sizeof (toc1->bitmap1_name))            &&
                   !strncmp (toc1->bitmap2_name, toc2->bitmap2_name,
                           sizeof (toc1->bitmap2_name)));
   }
   
   /**
    * ldm_validate_privheads - Compare the primary privhead with its backups
    * @bdev:  Device holding the LDM Database
    * @ph1:   Memory struct to fill with ph contents
    *
    * Read and compare all three privheads from disk.
    *
    * The privheads on disk show the size and location of the main disk area and
    * the configuration area (the database).
    *
    * Return:  TRUE   Success
    *          FALSE  Error
    */
   static BOOL ldm_validate_privheads (struct block_device *bdev,
           unsigned long first_sector, struct privhead *ph1, struct gendisk *hd,
           unsigned long first_minor)
   {
           static const int off[3] = { OFF_PRIV1, OFF_PRIV2, OFF_PRIV3 };
           struct privhead *ph[3] = { ph1 };
           Sector sect;
           u8 *data;
           BOOL result = FALSE;
           long num_sects;
           int i;
   
           BUG_ON (!bdev);
           BUG_ON (!ph1);
   
           ph[1] = kmalloc (sizeof (*ph[1]), GFP_KERNEL);
           ph[2] = kmalloc (sizeof (*ph[2]), GFP_KERNEL);
           if (!ph[1] || !ph[2]) {
                   ldm_crit ("Out of memory.");
                   goto out;
           }
   
           /* off[1 & 2] are relative to ph[0]->config_start */
           ph[0]->config_start = 0;
   
           /* Read and parse privheads */
           for (i = 0; i < 3; i++) {
                   data = read_dev_sector (bdev,
                           first_sector + ph[0]->config_start + off[i], &sect);
                   if (!data) {
                           ldm_crit ("Disk read failed.");
                           goto out;
                   }
                   result = ldm_parse_privhead (data, ph[i]);
                   put_dev_sector (sect);
                   if (!result) {
                           ldm_error ("Cannot find PRIVHEAD %d.", i+1); /* Log again */
                           if (i < 2)
                                   goto out;       /* Already logged */
                           else
                                   break;  /* FIXME ignore for now, 3rd PH can fail on odd-sized disks */
                   }
           }
   
           num_sects = hd->part[(first_minor >> hd->minor_shift)
                                   << hd->minor_shift].nr_sects;
   
           if ((ph[0]->config_start > num_sects) ||
              ((ph[0]->config_start + ph[0]->config_size) > num_sects)) {
                   ldm_crit ("Database extends beyond the end of the disk.");
                   goto out;
           }
   
           if ((ph[0]->logical_disk_start > ph[0]->config_start) ||
              ((ph[0]->logical_disk_start + ph[0]->logical_disk_size)
                       > ph[0]->config_start)) {
                   ldm_crit ("Disk and database overlap.");
                   goto out;
           }
   
           if (!ldm_compare_privheads (ph[0], ph[1])) {
                   ldm_crit ("Primary and backup PRIVHEADs don't match.");
                   goto out;
           }
           /* FIXME ignore this for now
           if (!ldm_compare_privheads (ph[0], ph[2])) {
                   ldm_crit ("Primary and backup PRIVHEADs don't match.");
                   goto out;
           }*/
           ldm_debug ("Validated PRIVHEADs successfully.");
           result = TRUE;
   out:
           kfree (ph[1]);
           kfree (ph[2]);
           return result;
   }
   
   /**
    * ldm_validate_tocblocks - Validate the table of contents and its backups
    * @bdev:  Device holding the LDM Database
    * @base:  Offset, into @bdev, of the database
    * @ldb:   Cache of the database structures
    *
    * Find and compare the four tables of contents of the LDM Database stored on
    * @bdev and return the parsed information into @toc1.
    *
    * The offsets and sizes of the configs are range-checked against a privhead.
    *
    * Return:  TRUE   @toc1 contains validated TOCBLOCK info
    *          FALSE  @toc1 contents are undefined
    */
   static BOOL ldm_validate_tocblocks (struct block_device *bdev,
           unsigned long base, struct ldmdb *ldb)
   {
           static const int off[4] = { OFF_TOCB1, OFF_TOCB2, OFF_TOCB3, OFF_TOCB4};
           struct tocblock *tb[4];
           struct privhead *ph;
           Sector sect;
           u8 *data;
           BOOL result = FALSE;
           int i;
   
           BUG_ON (!bdev);
           BUG_ON (!ldb);
   
           ph    = &ldb->ph;
           tb[0] = &ldb->toc;
           tb[1] = kmalloc (sizeof (*tb[1]), GFP_KERNEL);
           tb[2] = kmalloc (sizeof (*tb[2]), GFP_KERNEL);
           tb[3] = kmalloc (sizeof (*tb[3]), GFP_KERNEL);
           if (!tb[1] || !tb[2] || !tb[3]) {
                   ldm_crit ("Out of memory.");
                   goto out;
           }
   
           for (i = 0; i < 4; i++)         /* Read and parse all four toc's. */
           {
                   data = read_dev_sector (bdev, base + off[i], &sect);
                   if (!data) {
                           ldm_crit ("Disk read failed.");
                           goto out;
                   }
                   result = ldm_parse_tocblock (data, tb[i]);
                   put_dev_sector (sect);
                   if (!result)
                           goto out;       /* Already logged */
           }
   
           /* Range check the toc against a privhead. */
           if (((tb[0]->bitmap1_start + tb[0]->bitmap1_size) > ph->config_size) ||
               ((tb[0]->bitmap2_start + tb[0]->bitmap2_size) > ph->config_size)) {
                   ldm_crit ("The bitmaps are out of range.  Giving up.");
                   goto out;
           }
   
           if (!ldm_compare_tocblocks (tb[0], tb[1]) ||    /* Compare all tocs. */
               !ldm_compare_tocblocks (tb[0], tb[2]) ||
               !ldm_compare_tocblocks (tb[0], tb[3])) {
                   ldm_crit ("The TOCBLOCKs don't match.");
                   goto out;
           }
   
           ldm_debug ("Validated TOCBLOCKs successfully.");
           result = TRUE;
   out:
           kfree (tb[1]);
           kfree (tb[2]);
           kfree (tb[3]);
           return result;
   }
   
   /**
    * ldm_validate_vmdb - Read the VMDB and validate it
    * @bdev:  Device holding the LDM Database
    * @base:  Offset, into @bdev, of the database
    * @ldb:   Cache of the database structures
    *
    * Find the vmdb of the LDM Database stored on @bdev and return the parsed
    * information in @ldb.
    *
    * Return:  TRUE   @ldb contains validated VBDB info
    *          FALSE  @ldb contents are undefined
    */
   static BOOL ldm_validate_vmdb (struct block_device *bdev, unsigned long base,
                                  struct ldmdb *ldb)
   {
           Sector sect;
           u8 *data;
           BOOL result = FALSE;
           struct vmdb *vm;
           struct tocblock *toc;
   
           BUG_ON (!bdev);
           BUG_ON (!ldb);
   
           vm  = &ldb->vm;
           toc = &ldb->toc;
   
           data = read_dev_sector (bdev, base + OFF_VMDB, &sect);
           if (!data) {
                   ldm_crit ("Disk read failed.");
                   return FALSE;
           }
   
           if (!ldm_parse_vmdb (data, vm))
                   goto out;                               /* Already logged */
   
           /* Are there uncommitted transactions? */
           if (BE16(data + 0x10) != 0x01) {
                   ldm_crit ("Database is not in a consistant state.  Aborting.");
                   goto out;
           }
   
           if (vm->vblk_offset != 512)
                   ldm_info ("VBLKs start at offset 0x%04x.", vm->vblk_offset);
   
           /* FIXME: How should we handle this situation? */
           if ((vm->vblk_size * vm->last_vblk_seq) != (toc->bitmap1_size << 9))
                   ldm_info ("VMDB and TOCBLOCK don't agree on the database size.");
   
           result = TRUE;
   out:
           put_dev_sector (sect);
           return result;
   }
   
   
   /**
    * ldm_validate_partition_table - Determine whether bdev might be a dynamic disk
    * @bdev:  Device holding the LDM Database
    *
    * This function provides a weak test to decide whether the device is a dynamic
    * disk or not.  It looks for an MS-DOS-style partition table containing at
    * least one partition of type 0x42 (formerly SFS, now used by Windows for
    * dynamic disks).
    *
    * N.B.  The only possible error can come from the read_dev_sector and that is
    *       only likely to happen if the underlying device is strange.  If that IS
    *       the case we should return zero to let someone else try.
    *
    * Return:  TRUE   @bdev is a dynamic disk
    *          FALSE  @bdev is not a dynamic disk, or an error occurred
    */
   static BOOL ldm_validate_partition_table (struct block_device *bdev)
   {
           Sector sect;
           u8 *data;
           struct partition *p;
           int i;
           BOOL result = FALSE;
   
           BUG_ON (!bdev);
   
           data = read_dev_sector (bdev, 0, &sect);
           if (!data) {
                   ldm_crit ("Disk read failed.");
                   return FALSE;
           }
   
           if (*(u16*) (data + 0x01FE) != cpu_to_le16 (MSDOS_LABEL_MAGIC)) {
                   ldm_debug ("No MS-DOS partition table found.");
                   goto out;
           }
   
           p = (struct partition*)(data + 0x01BE);
           for (i = 0; i < 4; i++, p++)
                   if (SYS_IND (p) == WIN2K_DYNAMIC_PARTITION) {
                           result = TRUE;
                           break;
                   }
   
           if (result)
                   ldm_debug ("Parsed partition table successfully.");
           else
                   ldm_debug ("Found an MS-DOS partition table, not a dynamic disk.");
   out:
           put_dev_sector (sect);
           return result;
   }
   
   /**
    * ldm_get_disk_objid - Search a linked list of vblk's for a given Disk Id
    * @ldb:  Cache of the database structures
    *
    * The LDM Database contains a list of all partitions on all dynamic disks.  The
    * primary PRIVHEAD, at the beginning of the physical disk, tells us the GUID of
    * this disk.  This function searches for the GUID in a linked list of vblk's.
    *
    * Return:  Pointer, A matching vblk was found
    *          NULL,    No match, or an error
    */
   static struct vblk * ldm_get_disk_objid (const struct ldmdb *ldb)
   {
           struct list_head *item;
   
           BUG_ON (!ldb);
   
           list_for_each (item, &ldb->v_disk) {
                   struct vblk *v = list_entry (item, struct vblk, list);
                   if (!memcmp (v->vblk.disk.disk_id, ldb->ph.disk_id, GUID_SIZE))
                           return v;
           }
   
           return NULL;
   }
   
   /**
    * ldm_create_partition - Create a kernel partition device
    * @hd:     gendisk structure in which to create partition
    * @minor:  Create a this minor number on the device
    * @start:  Offset (in sectors) into the device of the partition
    * @size:   Size (in sectors) of the partition
    *
    * This validates the range, then puts an entry into the kernel's partition
    * table.
    *
    * Return:  TRUE   Created the partition
    *          FALSE  Error
    */
   static BOOL ldm_create_partition (struct gendisk *hd, int minor, int start,
                                     int size)
   {
           int disk_minor;
   
           BUG_ON (!hd);;
           BUG_ON (!hd->part);
   
           /* Get the minor number of the parent device
            * so we can check we don't go beyond the end of the device.  */
           disk_minor = (minor >> hd->minor_shift) << hd->minor_shift;
           if ((start < 1) || ((start + size) > hd->part[disk_minor].nr_sects)) {
                   ldm_crit ("Partition exceeds physical disk. Aborting.");
                   return FALSE;
           }
           add_gd_partition (hd, minor, start, size);
           ldm_debug ("Created partition successfully.");
           return TRUE;
   }
   
   /**
    * ldm_create_data_partitions - Create data partitions for this device
    * @pp:   List of the partitions parsed so far
    * @ldb:  Cache of the database structures
    *
    * The database contains ALL the partitions for ALL disk groups, so we need to
    * filter out this specific disk. Using the disk's object id, we can find all
    * the partitions in the database that belong to this disk.
    *
    * Add each partition in our database, to the parsed_partitions structure.
    *
    * N.B.  This function creates the partitions in the order it finds partition
    *       objects in the linked list.
    *
    * Return:  TRUE   Partition created
    *          FALSE  Error, probably a range checking problem
    */
   static BOOL ldm_create_data_partitions (struct gendisk *hd,
           unsigned long first_sector, int first_minor, const struct ldmdb *ldb)
   {
           struct list_head *item;
           struct vblk_part *part;
           struct vblk *disk;
           int disk_minor;
           int minor;
   
           BUG_ON (!hd);
           BUG_ON (!ldb);
   
           disk = ldm_get_disk_objid (ldb);
           if (!disk) {
                   ldm_crit ("Can't find the ID of this disk in the database.");
                   return FALSE;
           }
   
           /* We use the range-check the partitions against the parent device. */
           disk_minor = (first_minor >> hd->minor_shift) << hd->minor_shift;
           minor = first_minor;
   
           printk (" [LDM]");
   
           /* Create the data partitions */
           list_for_each (item, &ldb->v_part) {
                   struct vblk *vb;
                   vb = list_entry (item, struct vblk, list);
                   part = &vb->vblk.part;
   
                   if (part->disk_id != disk->obj_id)
                           continue;
   
                   if (!ldm_create_partition (hd, minor,
                       part->start + ldb->ph.logical_disk_start, part->size))
                           continue;                       /* Already logged */
                   minor++;
           }
   
           printk ("\n");
           return TRUE;
   }
   
   
   /**
    * ldm_relative - Calculate the next relative offset
    * @buffer:  Block of data being worked on
    * @buflen:  Size of the block of data
    * @base:    Size of the previous fixed width fields
    * @offset:  Cumulative size of the previous variable-width fields
    *
    * Because many of the VBLK fields are variable-width, it's necessary
    * to calculate each offset based on the previous one and the length
    * of the field it pointed to.
    *
    * Return:  -1 Error, the calculated offset exceeded the size of the buffer
    *           n OK, a range-checked offset into buffer
    */
   static int ldm_relative (const u8 *buffer, int buflen, int base, int offset)
   {
   
           base += offset;
           if ((!buffer) || (offset < 0) || (base > buflen))
                   return -1;
           if ((base + buffer[base]) >= buflen)
                   return -1;
   
           return buffer[base] + offset + 1;
   }
   
   /**
    * ldm_get_vnum - Convert a variable-width, big endian number, into cpu order
    * @block:  Pointer to the variable-width number to convert
    *
    * Large numbers in the LDM Database are often stored in a packed format.  Each
    * number is prefixed by a one byte width marker.  All numbers in the database
    * are stored in big-endian byte order.  This function reads one of these
    * numbers and returns the result
    *
    * N.B.  This function DOES NOT perform any range checking, though the most
    *       it will read is eight bytes.
    *
    * Return:  n A number
    *          0 Zero, or an error occurred
    */
   static u64 ldm_get_vnum (const u8 *block)
   {
           u64 tmp = 0;
           u8 length;
   
           BUG_ON (!block);
   
           length = *block++;
   
           if (length && length <= 8)
                   while (length--)
                           tmp = (tmp << 8) | *block++;
           else
                   ldm_error ("Illegal length %d.", length);
   
           return tmp;
   }
   
   /**
    * ldm_get_vstr - Read a length-prefixed string into a buffer
    * @block:   Pointer to the length marker
    * @buffer:  Location to copy string to
    * @buflen:  Size of the output buffer
    *
    * Many of the strings in the LDM Database are not NULL terminated.  Instead
    * they are prefixed by a one byte length marker.  This function copies one of
    * these strings into a buffer.
    *
    * N.B.  This function DOES NOT perform any range checking on the input.
    *       If the buffer is too small, the output will be truncated.
    *
    * Return:  0, Error and @buffer contents are undefined
    *          n, String length in characters (excluding NULL)
    *          buflen-1, String was truncated.
    */
   static int ldm_get_vstr (const u8 *block, u8 *buffer, int buflen)
   {
           int length;
   
           BUG_ON (!block);
           BUG_ON (!buffer);
   
           length = block[0];
           if (length >= buflen) {
                   ldm_error ("Truncating string %d -> %d.", length, buflen);
                   length = buflen - 1;
           }
           memcpy (buffer, block + 1, length);
           buffer[length] = 0;
           return length;
   }
   
   
   /**
    * ldm_parse_cmp3 - Read a raw VBLK Component object into a vblk structure
    * @buffer:  Block of data being worked on
    * @buflen:  Size of the block of data
    * @vb:      In-memory vblk in which to return information
    *
    * Read a raw VBLK Component object (version 3) into a vblk structure.
    *
    * Return:  TRUE   @vb contains a Component VBLK
    *          FALSE  @vb contents are not defined
    */
   static BOOL ldm_parse_cmp3 (const u8 *buffer, int buflen, struct vblk *vb)
   {
           int r_objid, r_name, r_vstate, r_child, r_parent, r_stripe, r_cols, len;
           struct vblk_comp *comp;
   
           BUG_ON (!buffer);
           BUG_ON (!vb);
   
           r_objid  = ldm_relative (buffer, buflen, 0x18, 0);
           r_name   = ldm_relative (buffer, buflen, 0x18, r_objid);
           r_vstate = ldm_relative (buffer, buflen, 0x18, r_name);
           r_child  = ldm_relative (buffer, buflen, 0x1D, r_vstate);
           r_parent = ldm_relative (buffer, buflen, 0x2D, r_child);
   
           if (buffer[0x12] & VBLK_FLAG_COMP_STRIPE) {
                   r_stripe = ldm_relative (buffer, buflen, 0x2E, r_parent);
                   r_cols   = ldm_relative (buffer, buflen, 0x2E, r_stripe);
                   len = r_cols;
           } else {
                   r_stripe = 0;
                   r_cols   = 0;
                   len = r_parent;
           }
           if (len < 0)
                   return FALSE;
   
           len += VBLK_SIZE_CMP3;
           if (len != BE32 (buffer + 0x14))
                   return FALSE;
   
           comp = &vb->vblk.comp;
           ldm_get_vstr (buffer + 0x18 + r_name, comp->state,
                   sizeof (comp->state));
           comp->type      = buffer[0x18 + r_vstate];
           comp->children  = ldm_get_vnum (buffer + 0x1D + r_vstate);
           comp->parent_id = ldm_get_vnum (buffer + 0x2D + r_child);
           comp->chunksize = r_stripe ? ldm_get_vnum (buffer+r_parent+0x2E) : 0;
   
           return TRUE;
   }
   
   /**
    * ldm_parse_dgr3 - Read a raw VBLK Disk Group object into a vblk structure
    * @buffer:  Block of data being worked on
    * @buflen:  Size of the block of data
    * @vb:      In-memory vblk in which to return information
    *
    * Read a raw VBLK Disk Group object (version 3) into a vblk structure.
    *
    * Return:  TRUE   @vb contains a Disk Group VBLK
    *          FALSE  @vb contents are not defined
    */
   static int ldm_parse_dgr3 (const u8 *buffer, int buflen, struct vblk *vb)
   {
           int r_objid, r_name, r_diskid, r_id1, r_id2, len;
           struct vblk_dgrp *dgrp;
   
           BUG_ON (!buffer);
           BUG_ON (!vb);
   
           r_objid  = ldm_relative (buffer, buflen, 0x18, 0);
           r_name   = ldm_relative (buffer, buflen, 0x18, r_objid);
           r_diskid = ldm_relative (buffer, buflen, 0x18, r_name);
   
           if (buffer[0x12] & VBLK_FLAG_DGR3_IDS) {
                   r_id1 = ldm_relative (buffer, buflen, 0x24, r_diskid);
                   r_id2 = ldm_relative (buffer, buflen, 0x24, r_id1);
                   len = r_id2;
           } else {
                   r_id1 = 0;
                   r_id2 = 0;
                   len = r_diskid;
           }
           if (len < 0)
                   return FALSE;
   
           len += VBLK_SIZE_DGR3;
           if (len != BE32 (buffer + 0x14))
                   return FALSE;
   
           dgrp = &vb->vblk.dgrp;
           ldm_get_vstr (buffer + 0x18 + r_name, dgrp->disk_id,
                   sizeof (dgrp->disk_id));
           return TRUE;
   }
   
   /**
    * ldm_parse_dgr4 - Read a raw VBLK Disk Group object into a vblk structure
    * @buffer:  Block of data being worked on
    * @buflen:  Size of the block of data
    * @vb:      In-memory vblk in which to return information
    *
    * Read a raw VBLK Disk Group object (version 4) into a vblk structure.
    *
    * Return:  TRUE   @vb contains a Disk Group VBLK
    *          FALSE  @vb contents are not defined
    */
   static BOOL ldm_parse_dgr4 (const u8 *buffer, int buflen, struct vblk *vb)
   {
           char buf[64];
           int r_objid, r_name, r_id1, r_id2, len;
           struct vblk_dgrp *dgrp;
   
           BUG_ON (!buffer);
           BUG_ON (!vb);
   
           r_objid  = ldm_relative (buffer, buflen, 0x18, 0);
           r_name   = ldm_relative (buffer, buflen, 0x18, r_objid);
   
           if (buffer[0x12] & VBLK_FLAG_DGR4_IDS) {
                   r_id1 = ldm_relative (buffer, buflen, 0x44, r_name);
                   r_id2 = ldm_relative (buffer, buflen, 0x44, r_id1);
                   len = r_id2;
           } else {
                   r_id1 = 0;
                   r_id2 = 0;
                   len = r_name;
           }
           if (len < 0)
                   return FALSE;
   
           len += VBLK_SIZE_DGR4;
           if (len != BE32 (buffer + 0x14))
                   return FALSE;
   
           dgrp = &vb->vblk.dgrp;
   
           ldm_get_vstr (buffer + 0x18 + r_objid, buf, sizeof (buf));
           return TRUE;
   }
   
   /**
    * ldm_parse_dsk3 - Read a raw VBLK Disk object into a vblk structure
    * @buffer:  Block of data being worked on
    * @buflen:  Size of the block of data
    * @vb:      In-memory vblk in which to return information
    *
    * Read a raw VBLK Disk object (version 3) into a vblk structure.
    *
    * Return:  TRUE   @vb contains a Disk VBLK
    *          FALSE  @vb contents are not defined
    */
   static BOOL ldm_parse_dsk3 (const u8 *buffer, int buflen, struct vblk *vb)
   {
           int r_objid, r_name, r_diskid, r_altname, len;
           struct vblk_disk *disk;
   
           BUG_ON (!buffer);
           BUG_ON (!vb);
   
           r_objid   = ldm_relative (buffer, buflen, 0x18, 0);
           r_name    = ldm_relative (buffer, buflen, 0x18, r_objid);
           r_diskid  = ldm_relative (buffer, buflen, 0x18, r_name);
           r_altname = ldm_relative (buffer, buflen, 0x18, r_diskid);
           len = r_altname;
           if (len < 0)
                   return FALSE;
   
           len += VBLK_SIZE_DSK3;
           if (len != BE32 (buffer + 0x14))
                   return FALSE;
   
           disk = &vb->vblk.disk;
           ldm_get_vstr (buffer + 0x18 + r_diskid, disk->alt_name,
                   sizeof (disk->alt_name));
           if (!ldm_parse_guid (buffer + 0x19 + r_name, disk->disk_id))
                   return FALSE;
   
           return TRUE;
   }
   
   /**
    * ldm_parse_dsk4 - Read a raw VBLK Disk object into a vblk structure
    * @buffer:  Block of data being worked on
    * @buflen:  Size of the block of data
    * @vb:      In-memory vblk in which to return information
    *
    * Read a raw VBLK Disk object (version 4) into a vblk structure.
    *
    * Return:  TRUE   @vb contains a Disk VBLK
    *          FALSE  @vb contents are not defined
    */
  static BOOL ldm_parse_dsk4 (const u8 *buffer, int buflen, struct vblk *vb)
  {
          int r_objid, r_name, len;
          struct vblk_disk *disk;
  
          BUG_ON (!buffer);
          BUG_ON (!vb);
  
          r_objid = ldm_relative (buffer, buflen, 0x18, 0);
          r_name  = ldm_relative (buffer, buflen, 0x18, r_objid);
          len     = r_name;
          if (len < 0)
                  return FALSE;
  
          len += VBLK_SIZE_DSK4;
          if (len != BE32 (buffer + 0x14))
                  return FALSE;
  
          disk = &vb->vblk.disk;
          memcpy (disk->disk_id, buffer + 0x18 + r_name, GUID_SIZE);
          return TRUE;
  }
  
  /**
   * ldm_parse_prt3 - Read a raw VBLK Partition object into a vblk structure
   * @buffer:  Block of data being worked on
   * @buflen:  Size of the block of data
   * @vb:      In-memory vblk in which to return information
   *
   * Read a raw VBLK Partition object (version 3) into a vblk structure.
   *
   * Return:  TRUE   @vb contains a Partition VBLK
   *          FALSE  @vb contents are not defined
   */
  static BOOL ldm_parse_prt3 (const u8 *buffer, int buflen, struct vblk *vb)
  {
          int r_objid, r_name, r_size, r_parent, r_diskid, r_index, len;
          struct vblk_part *part;
  
          BUG_ON (!buffer);
          BUG_ON (!vb);
  
          r_objid  = ldm_relative (buffer, buflen, 0x18, 0);
          r_name   = ldm_relative (buffer, buflen, 0x18, r_objid);
          r_size   = ldm_relative (buffer, buflen, 0x34, r_name);
          r_parent = ldm_relative (buffer, buflen, 0x34, r_size);
          r_diskid = ldm_relative (buffer, buflen, 0x34, r_parent);
  
          if (buffer[0x12] & VBLK_FLAG_PART_INDEX) {
                  r_index = ldm_relative (buffer, buflen, 0x34, r_diskid);
                  len = r_index;
          } else {
                  r_index = 0;
                  len = r_diskid;
          }
          if (len < 0)
                  return FALSE;
  
          len += VBLK_SIZE_PRT3;
          if (len != BE32 (buffer + 0x14))
                  return FALSE;
  
          part = &vb->vblk.part;
          part->start         = BE64         (buffer + 0x24 + r_name);
          part->volume_offset = BE64         (buffer + 0x2C + r_name);
          part->size          = ldm_get_vnum (buffer + 0x34 + r_name);
          part->parent_id     = ldm_get_vnum (buffer + 0x34 + r_size);
          part->disk_id       = ldm_get_vnum (buffer + 0x34 + r_parent);
          if (vb->flags & VBLK_FLAG_PART_INDEX)
                  part->partnum = buffer[0x35 + r_diskid];
          else
                  part->partnum = 0;
  
          return TRUE;
  }
  
  /**
   * ldm_parse_vol5 - Read a raw VBLK Volume object into a vblk structure
   * @buffer:  Block of data being worked on
   * @buflen:  Size of the block of data
   * @vb:      In-memory vblk in which to return information
   *
   * Read a raw VBLK Volume object (version 5) into a vblk structure.
   *
   * Return:  TRUE   @vb contains a Volume VBLK
   *          FALSE  @vb contents are not defined
   */
  static BOOL ldm_parse_vol5 (const u8 *buffer, int buflen, struct vblk *vb)
  {
          int r_objid, r_name, r_vtype, r_child, r_size, r_id1, r_id2, r_size2;
          int r_drive, len;
          struct vblk_volu *volu;
  
          BUG_ON (!buffer);
          BUG_ON (!vb);
  
          r_objid  = ldm_relative (buffer, buflen, 0x18, 0);
          r_name   = ldm_relative (buffer, buflen, 0x18, r_objid);
          r_vtype  = ldm_relative (buffer, buflen, 0x18, r_name);
          r_child  = ldm_relative (buffer, buflen, 0x2E, r_vtype);
          r_size   = ldm_relative (buffer, buflen, 0x3E, r_child);
  
          if (buffer[0x12] & VBLK_FLAG_VOLU_ID1)
                  r_id1 = ldm_relative (buffer, buflen, 0x53, r_size);
          else
                  r_id1 = r_size;
  
          if (buffer[0x12] & VBLK_FLAG_VOLU_ID2)
                  r_id2 = ldm_relative (buffer, buflen, 0x53, r_id1);
          else
                  r_id2 = r_id1;
  
          if (buffer[0x12] & VBLK_FLAG_VOLU_SIZE)
                  r_size2 = ldm_relative (buffer, buflen, 0x53, r_id2);
          else
                  r_size2 = r_id2;
  
          if (buffer[0x12] & VBLK_FLAG_VOLU_DRIVE)
                  r_drive = ldm_relative (buffer, buflen, 0x53, r_size2);
          else
                  r_drive = r_size2;
  
          len = r_drive;
          if (len < 0)
                  return FALSE;
  
          len += VBLK_SIZE_VOL5;
          if (len != BE32 (buffer + 0x14))
                  return FALSE;
  
          volu = &vb->vblk.volu;
  
          ldm_get_vstr (buffer + 0x18 + r_name,  volu->volume_type,
                  sizeof (volu->volume_type));
          memcpy (volu->volume_state, buffer + 0x19 + r_vtype,
                          sizeof (volu->volume_state));
          volu->size = ldm_get_vnum (buffer + 0x3E + r_child);
          volu->partition_type = buffer[0x42 + r_size];
          memcpy (volu->guid, buffer + 0x43 + r_size,  sizeof (volu->guid));
          if (buffer[0x12] & VBLK_FLAG_VOLU_DRIVE) {
                  ldm_get_vstr (buffer + 0x53 + r_size,  volu->drive_hint,
                          sizeof (volu->drive_hint));
          }
          return TRUE;
  }
  
  /**
   * ldm_parse_vblk - Read a raw VBLK object into a vblk structure
   * @buf:  Block of data being worked on
   * @len:  Size of the block of data
   * @vb:   In-memory vblk in which to return information
   *
   * Read a raw VBLK object into a vblk structure.  This function just reads the
   * information common to all VBLK types, then delegates the rest of the work to
   * helper functions: ldm_parse_*.
   *
   * Return:  TRUE   @vb contains a VBLK
   *          FALSE  @vb contents are not defined
   */
  static BOOL ldm_parse_vblk (const u8 *buf, int len, struct vblk *vb)
  {
          BOOL result = FALSE;
          int r_objid;
  
          BUG_ON (!buf);
          BUG_ON (!vb);
  
          r_objid = ldm_relative (buf, len, 0x18, 0);
          if (r_objid < 0) {
                  ldm_error ("VBLK header is corrupt.");
                  return FALSE;
          }
  
          vb->flags  = buf[0x12];
          vb->type   = buf[0x13];
          vb->obj_id = ldm_get_vnum (buf + 0x18);
          ldm_get_vstr (buf+0x18+r_objid, vb->name, sizeof (vb->name));
  
          switch (vb->type) {
                  case VBLK_CMP3:  result = ldm_parse_cmp3 (buf, len, vb); break;
                  case VBLK_DSK3:  result = ldm_parse_dsk3 (buf, len, vb); break;
                  case VBLK_DSK4:  result = ldm_parse_dsk4 (buf, len, vb); break;
                  case VBLK_DGR3:  result = ldm_parse_dgr3 (buf, len, vb); break;
                  case VBLK_DGR4:  result = ldm_parse_dgr4 (buf, len, vb); break;
                  case VBLK_PRT3:  result = ldm_parse_prt3 (buf, len, vb); break;
                  case VBLK_VOL5:  result = ldm_parse_vol5 (buf, len, vb); break;
          }
  
          if (result)
                  ldm_debug ("Parsed VBLK 0x%llx (type: 0x%02x) ok.",
                           (unsigned long long) vb->obj_id, vb->type);
          else
                  ldm_error ("Failed to parse VBLK 0x%llx (type: 0x%02x).",
                          (unsigned long long) vb->obj_id, vb->type);
  
          return result;
  }
  
  
  /**
   * ldm_ldmdb_add - Adds a raw VBLK entry to the ldmdb database
   * @data:  Raw VBLK to add to the database
   * @len:   Size of the raw VBLK
   * @ldb:   Cache of the database structures
   *
   * The VBLKs are sorted into categories.  Partitions are also sorted by offset.
   *
   * N.B.  This function does not check the validity of the VBLKs.
   *
   * Return:  TRUE   The VBLK was added
   *          FALSE  An error occurred
   */
  static BOOL ldm_ldmdb_add (u8 *data, int len, struct ldmdb *ldb)
  {
          struct vblk *vb;
          struct list_head *item;
  
          BUG_ON (!data);
          BUG_ON (!ldb);
  
          vb = kmalloc (sizeof (*vb), GFP_KERNEL);
          if (!vb) {
                  ldm_crit ("Out of memory.");
                  return FALSE;
          }
  
          if (!ldm_parse_vblk (data, len, vb)) {
                  kfree(vb);
                  return FALSE;                   /* Already logged */
          }
  
          /* Put vblk into the correct list. */
          switch (vb->type) {
          case VBLK_DGR3:
          case VBLK_DGR4:
                  list_add (&vb->list, &ldb->v_dgrp);
                  break;
          case VBLK_DSK3:
          case VBLK_DSK4:
                  list_add (&vb->list, &ldb->v_disk);
                  break;
          case VBLK_VOL5:
                  list_add (&vb->list, &ldb->v_volu);
                  break;
          case VBLK_CMP3:
                  list_add (&vb->list, &ldb->v_comp);
                  break;
          case VBLK_PRT3:
                  /* Sort by the partition's start sector. */
                  list_for_each (item, &ldb->v_part) {
                          struct vblk *v = list_entry (item, struct vblk, list);
                          if ((v->vblk.part.disk_id == vb->vblk.part.disk_id) &&
                              (v->vblk.part.start > vb->vblk.part.start)) {
                                  list_add_tail (&vb->list, &v->list);
                                  return TRUE;
                          }
                  }
                  list_add_tail (&vb->list, &ldb->v_part);
                  break;
          }
          return TRUE;
  }
  
  /**
   * ldm_frag_add - Add a VBLK fragment to a list
   * @data:   Raw fragment to be added to the list
   * @size:   Size of the raw fragment
   * @frags:  Linked list of VBLK fragments
   *
   * Fragmented VBLKs may not be consecutive in the database, so they are placed
   * in a list so they can be pieced together later.
   *
   * Return:  TRUE   Success, the VBLK was added to the list
   *          FALSE  Error, a problem occurred
   */
  static BOOL ldm_frag_add (const u8 *data, int size, struct list_head *frags)
  {
          struct frag *f;
          struct list_head *item;
          int rec, num, group;
  
          BUG_ON (!data);
          BUG_ON (!frags);
  
          group = BE32 (data + 0x08);
          rec   = BE16 (data + 0x0C);
          num   = BE16 (data + 0x0E);
          if ((num < 1) || (num > 4)) {
                  ldm_error ("A VBLK claims to have %d parts.", num);
                  return FALSE;
          }
  
          list_for_each (item, frags) {
                  f = list_entry (item, struct frag, list);
                  if (f->group == group)
                          goto found;
          }
  
          f = kmalloc (sizeof (*f) + size*num, GFP_KERNEL);
          if (!f) {
                  ldm_crit ("Out of memory.");
                  return FALSE;
          }
  
          f->group = group;
          f->num   = num;
          f->rec   = rec;
          f->map   = 0xFF << num;
  
          list_add_tail (&f->list, frags);
  found:
          if (f->map & (1 << rec)) {
                  ldm_error ("Duplicate VBLK, part %d.", rec);
                  f->map &= 0x7F;                 /* Mark the group as broken */
                  return FALSE;
          }
  
          f->map |= (1 << rec);
  
          if (num > 0) {
                  data += VBLK_SIZE_HEAD;
                  size -= VBLK_SIZE_HEAD;
          }
          memcpy (f->data+rec*(size-VBLK_SIZE_HEAD)+VBLK_SIZE_HEAD, data, size);
  
          return TRUE;
  }
  
  /**
   * ldm_frag_free - Free a linked list of VBLK fragments
   * @list:  Linked list of fragments
   *
   * Free a linked list of VBLK fragments
   *
   * Return:  none
   */
  static void ldm_frag_free (struct list_head *list)
  {
          struct list_head *item, *tmp;
  
          BUG_ON (!list);
  
          list_for_each_safe (item, tmp, list)
                  kfree (list_entry (item, struct frag, list));
  }
  
  /**
   * ldm_frag_commit - Validate fragmented VBLKs and add them to the database
   * @frags:  Linked list of VBLK fragments
   * @ldb:    Cache of the database structures
   *
   * Now that all the fragmented VBLKs have been collected, they must be added to
   * the database for later use.
   *
   * Return:  TRUE   All the fragments we added successfully
   *          FALSE  One or more of the fragments we invalid
   */
  static BOOL ldm_frag_commit (struct list_head *frags, struct ldmdb *ldb)
  {
          struct frag *f;
          struct list_head *item;
  
          BUG_ON (!frags);
          BUG_ON (!ldb);
  
          list_for_each (item, frags) {
                  f = list_entry (item, struct frag, list);
  
                  if (f->map != 0xFF) {
                          ldm_error ("VBLK group %d is incomplete (0x%02x).",
                                  f->group, f->map);
                          return FALSE;
                  }
  
                  if (!ldm_ldmdb_add (f->data, f->num*ldb->vm.vblk_size, ldb))
                          return FALSE;           /* Already logged */
          }
          return TRUE;
  }
  
  /**
   * ldm_get_vblks - Read the on-disk database of VBLKs into memory
   * @bdev:  Device holding the LDM Database
   * @base:  Offset, into @bdev, of the database
   * @ldb:   Cache of the database structures
   *
   * To use the information from the VBLKs, they need to be read from the disk,
   * unpacked and validated.  We cache them in @ldb according to their type.
   *
   * Return:  TRUE   All the VBLKs were read successfully
   *          FALSE  An error occurred
   */
  static BOOL ldm_get_vblks (struct block_device *bdev, unsigned long base,
                             struct ldmdb *ldb)
  {
          int size, perbuf, skip, finish, s, v, recs;
          u8 *data = NULL;
          Sector sect;
          BOOL result = FALSE;
          LIST_HEAD (frags);
  
          BUG_ON (!bdev);
          BUG_ON (!ldb);
  
          size   = ldb->vm.vblk_size;
          perbuf = 512 / size;
          skip   = ldb->vm.vblk_offset >> 9;              /* Bytes to sectors */
          finish = (size * ldb->vm.last_vblk_seq) >> 9;
  
          for (s = skip; s < finish; s++) {               /* For each sector */
                  data = read_dev_sector (bdev, base + OFF_VMDB + s, &sect);
                  if (!data) {
                          ldm_crit ("Disk read failed.");
                          goto out;
                  }
  
                  for (v = 0; v < perbuf; v++, data+=size) {  /* For each vblk */
                          if (MAGIC_VBLK != BE32 (data)) {
                                  ldm_error ("Expected to find a VBLK.");
                                  goto out;
                          }
  
                          recs = BE16 (data + 0x0E);      /* Number of records */
                          if (recs == 1) {
                                  if (!ldm_ldmdb_add (data, size, ldb))
                                          goto out;       /* Already logged */
                          } else if (recs > 1) {
                                  if (!ldm_frag_add (data, size, &frags))
                                          goto out;       /* Already logged */
                          }
                          /* else Record is not in use, ignore it. */
                  }
                  put_dev_sector (sect);
                  data = NULL;
          }
  
          result = ldm_frag_commit (&frags, ldb); /* Failures, already logged */
  out:
          if (data)
                  put_dev_sector (sect);
          ldm_frag_free (&frags);
  
          return result;
  }
  
  /**
   * ldm_free_vblks - Free a linked list of vblk's
   * @lh:  Head of a linked list of struct vblk
   *
   * Free a list of vblk's and free the memory used to maintain the list.
   *
   * Return:  none
   */
  static void ldm_free_vblks (struct list_head *lh)
  {
          struct list_head *item, *tmp;
  
          BUG_ON (!lh);
  
          list_for_each_safe (item, tmp, lh)
                  kfree (list_entry (item, struct vblk, list));
  }
  
  
  /**
   * ldm_partition - Find out whether a device is a dynamic disk and handle it
   * @hd:            gendisk structure in which to return the handled disk
   * @bdev:          Device we need to look at
   * @first_sector:  First sector within the device
   * @first_minor:   First minor number of partitions for the device
   *
   * This determines whether the device @bdev is a dynamic disk and if so creates
   * the partitions necessary in the gendisk structure pointed to by @hd.
   *
   * We create a dummy device 1, which contains the LDM database, and then create
   * each partition described by the LDM database in sequence as devices 2+. For
   * example, if the device is hda, we would have: hda1: LDM database, hda2, hda3,
   * and so on: the actual data containing partitions.
   *
   * Return:  1 Success, @bdev is a dynamic disk and we handled it
   *          0 Success, @bdev is not a dynamic disk
   *         -1 An error occurred before enough information had been read
   *            Or @bdev is a dynamic disk, but it may be corrupted
   */
  int ldm_partition (struct gendisk *hd, struct block_device *bdev,
          unsigned long first_sector, int first_minor)
  {
          struct ldmdb  *ldb;
          unsigned long base;
          int result = -1;
  
          BUG_ON (!hd);
          BUG_ON (!bdev);
  
          /* Look for signs of a Dynamic Disk */
          if (!ldm_validate_partition_table (bdev))
                  return 0;
  
          ldb = kmalloc (sizeof (*ldb), GFP_KERNEL);
          if (!ldb) {
                  ldm_crit ("Out of memory.");
                  goto out;
          }
  
          /* Parse and check privheads. */
          if (!ldm_validate_privheads (bdev, first_sector, &ldb->ph, hd, first_minor))
                  goto out;               /* Already logged */
  
          /* All further references are relative to base (database start). */
          base = first_sector + ldb->ph.config_start;
  
          /* Parse and check tocs and vmdb. */
          if (!ldm_validate_tocblocks (bdev, base, ldb) ||
              !ldm_validate_vmdb      (bdev, base, ldb))
                  goto out;               /* Already logged */
  
          /* Initialize vblk lists in ldmdb struct */
          INIT_LIST_HEAD (&ldb->v_dgrp);
          INIT_LIST_HEAD (&ldb->v_disk);
          INIT_LIST_HEAD (&ldb->v_volu);
          INIT_LIST_HEAD (&ldb->v_comp);
          INIT_LIST_HEAD (&ldb->v_part);
  
          if (!ldm_get_vblks (bdev, base, ldb)) {
                  ldm_crit ("Failed to read the VBLKs from the database.");
                  goto cleanup;
          }
  
          /* Finally, create the data partition devices. */
          if (ldm_create_data_partitions (hd, first_sector, first_minor, ldb)) {
                  ldm_debug ("Parsed LDM database successfully.");
                  result = 1;
          }
          /* else Already logged */
  
  cleanup:
          ldm_free_vblks (&ldb->v_dgrp);
          ldm_free_vblks (&ldb->v_disk);
          ldm_free_vblks (&ldb->v_volu);
          ldm_free_vblks (&ldb->v_comp);
          ldm_free_vblks (&ldb->v_part);
  out:
          kfree (ldb);
          return result;
  }
  

Cache object: a20fd02b1e15d97c4ca3a8c9ece95a86