super-mbr.c

   1 /*
   2  * mdadm - manage Linux "md" devices aka RAID arrays.
   3  *
   4  * Copyright (C) 2010 Neil Brown <neilb@suse.de>
   5  *
   6  *
   7  *    This program is free software; you can redistribute it and/or modify
   8  *    it under the terms of the GNU General Public License as published by
   9  *    the Free Software Foundation; either version 2 of the License, or
  10  *    (at your option) any later version.
  11  *
  12  *    This program is distributed in the hope that it will be useful,
  13  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *    GNU General Public License for more details.
  16  *
  17  *    You should have received a copy of the GNU General Public License
  18  *    along with this program; if not, write to the Free Software
  19  *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  *
  21  *    Author: Neil Brown
  22  *    Email: <neil@brown.name>
  23  *
  24  */
  25
  26 /*
  27  * 'mbr' is a pseudo metadata type for devices which have a
  28  * partition table in the Master Boot Record (mbr) also known
  29  * as a dos partition table.
  30  *
  31  * Obviously arrays cannot be created or assembled for this type.
  32  * It is used to allow a new bare device to have an partition table
  33  * added so the member partitions can then be included in other
  34  * arrays as relevant.
  35  *
  36  * The meaning operations are:
  37  * examine_super, but not brief_examine_super or export_examine
  38  * load_super
  39  * store_super
  40  */
  41
  42 #include "mdadm.h"
  43 #include "part.h"
  44
  45 static void free_mbr(struct supertype *st)
  46 {
  47         free(st->sb);
  48         st->sb = NULL;
  49 }
  50
  51 static void examine_mbr(struct supertype *st, char *homehost)
  52 {
  53         struct MBR *sb = st->sb;
  54         int i;
  55
  56         printf("   MBR Magic : %04x\n", sb->magic);
  57         for (i = 0; i < MBR_PARTITIONS; i++)
  58                 /*
  59                  * Have to make every access through sb rather than using a
  60                  * pointer to the partition table (or an entry), since the
  61                  * entries are not properly aligned.
  62                  */
  63                 if (sb->parts[i].blocks_num)
  64                         printf("Partition[%d] : %12lu sectors at %12lu (type %02x)\n",
  65                                i,
  66                                (unsigned long)__le32_to_cpu(sb->parts[i].blocks_num),
  67                                (unsigned long)__le32_to_cpu(sb->parts[i].first_sect_lba),
  68                                sb->parts[i].part_type);
  69
  70 }
  71
  72 static int load_super_mbr(struct supertype *st, int fd, char *devname)
  73 {
  74         /* try to read an mbr
  75          * Return
  76          *  0 on success
  77          *  1 cannot get record
  78          *  2 record is meaningless
  79          */
  80         struct MBR *super;
  81
  82         free_mbr(st);
  83
  84         if (posix_memalign((void**)&super, 512, 512) != 0) {
  85                 pr_err("could not allocate superblock\n");
  86                 return 1;
  87         }
  88
  89         lseek(fd, 0, 0);
  90         if (read(fd, super, sizeof(*super)) != sizeof(*super)) {
  91                 if (devname)
  92                         pr_err("Cannot read partition table on %s\n",
  93                                 devname);
  94                 free(super);
  95                 return 1;
  96         }
  97
  98         if (super->magic != MBR_SIGNATURE_MAGIC) {
  99                 if (devname)
 100                         pr_err("No partition table found on %s\n",
 101                                 devname);
 102                 free(super);
 103                 return 1;
 104         }
 105
 106         st->sb = super;
 107
 108         if (st->ss == NULL) {
 109                 st->ss = &mbr;
 110                 st->minor_version = 0;
 111                 st->max_devs = 1;
 112                 st->info = NULL;
 113         }
 114         return 0;
 115 }
 116
 117 static int store_mbr(struct supertype *st, int fd)
 118 {
 119         struct MBR *old, *super;
 120
 121         if (posix_memalign((void**)&old, 512, 512) != 0) {
 122                 pr_err("could not allocate superblock\n");
 123                 return 1;
 124         }
 125
 126         lseek(fd, 0, 0);
 127         if (read(fd, old, sizeof(*old)) != sizeof(*old)) {
 128                 free(old);
 129                 return 1;
 130         }
 131
 132         super = st->sb;
 133         memcpy(super->pad, old->pad, sizeof(super->pad));
 134         free(old);
 135         lseek(fd, 0, 0);
 136         if (write(fd, super, sizeof(*super)) != sizeof(*super))
 137                 return 4;
 138         fsync(fd);
 139         ioctl(fd, BLKRRPART, 0);
 140         return 0;
 141 }
 142
 143 static void getinfo_mbr(struct supertype *st, struct mdinfo *info, char *map)
 144 {
 145         struct MBR *sb = st->sb;
 146         int i;
 147
 148         memset(&info->array, 0, sizeof(info->array));
 149         memset(&info->disk, 0, sizeof(info->disk));
 150         strcpy(info->text_version, "mbr");
 151         strcpy(info->name, "mbr");
 152         info->component_size = 0;
 153
 154         for (i = 0; i < MBR_PARTITIONS ; i++)
 155                 /*
 156                  * Have to make every access through sb rather than using a
 157                  * pointer to the partition table (or an entry), since the
 158                  * entries are not properly aligned.
 159                  */
 160                 if (sb->parts[i].blocks_num) {
 161                         unsigned long last =
 162                                 (unsigned long)__le32_to_cpu(sb->parts[i].blocks_num)
 163                                 + (unsigned long)__le32_to_cpu(sb->parts[i].first_sect_lba);
 164                         if (last > info->component_size)
 165                                 info->component_size = last;
 166                 }
 167
 168 }
 169
 170 static struct supertype *match_metadata_desc(char *arg)
 171 {
 172         struct supertype *st;
 173
 174         if (strcmp(arg, "mbr") != 0)
 175                 return NULL;
 176
 177         st = xmalloc(sizeof(*st));
 178         st->ss = &mbr;
 179         st->info = NULL;
 180         st->minor_version = 0;
 181         st->max_devs = 1;
 182         st->sb = NULL;
 183         return st;
 184 }
 185
 186 static int validate_geometry(struct supertype *st, int level,
 187                              int layout, int raiddisks,
 188                              int *chunk, unsigned long long size,
 189                              unsigned long long data_offset,
 190                              char *subdev, unsigned long long *freesize,
 191                              int consistency_policy, int verbose)
 192 {
 193         pr_err("mbr metadata cannot be used this way\n");
 194         return 0;
 195 }
 196
 197 struct superswitch mbr = {
 198         .examine_super = examine_mbr,
 199         .validate_geometry = validate_geometry,
 200         .match_metadata_desc = match_metadata_desc,
 201         .load_super = load_super_mbr,
 202         .store_super = store_mbr,
 203         .getinfo_super = getinfo_mbr,
 204         .free_super = free_mbr,
 205         .name = "mbr",
 206 };