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 #ifndef MDASSEMBLE
  52
  53 static void examine_mbr(struct supertype *st, char *homehost)
  54 {
  55         struct MBR *sb = st->sb;
  56         int i;
  57
  58         printf("   MBR Magic : %04x\n", sb->magic);
  59         for (i = 0; i < MBR_PARTITIONS; i++)
  60                 if (sb->parts[i].blocks_num)
  61                         printf("Partition[%d] : %12lu sectors at %12lu (type %02x)\n",
  62                                i,
  63                                (unsigned long)__le32_to_cpu(sb->parts[i].blocks_num),
  64                                (unsigned long)__le32_to_cpu(sb->parts[i].first_sect_lba),
  65                                sb->parts[i].part_type);
  66
  67 }
  68
  69 #endif /*MDASSEMBLE */
  70
  71 static int load_super_mbr(struct supertype *st, int fd, char *devname)
  72 {
  73         /* try to read an mbr
  74          * Return
  75          *  0 on success
  76          *  1 cannot get record
  77          *  2 record is meaningless
  78          */
  79         struct MBR *super;
  80
  81         free_mbr(st);
  82
  83         if (posix_memalign((void**)&super, 512, 512) != 0) {
  84                 fprintf(stderr, Name ": %s could not allocate superblock\n",
  85                         __func__);
  86                 return 1;
  87         }
  88
  89         ioctl(fd, BLKFLSBUF, 0); /* make sure we read current data */
  90
  91         lseek(fd, 0, 0);
  92         if (read(fd, super, sizeof(*super)) != sizeof(*super)) {
  93                 if (devname)
  94                         fprintf(stderr, Name ": Cannot read partition table on %s\n",
  95                                 devname);
  96                 free(super);
  97                 return 1;
  98         }
  99
 100         if (super->magic != MBR_SIGNATURE_MAGIC) {
 101                 if (devname)
 102                         fprintf(stderr, Name ": No partition table found on %s\n",
 103                                 devname);
 104                 free(super);
 105                 return 1;
 106         }
 107
 108         st->sb = super;
 109
 110         if (st->ss == NULL) {
 111                 st->ss = &mbr;
 112                 st->minor_version = 0;
 113                 st->max_devs = 1;
 114                 st->info = NULL;
 115         }
 116         return 0;
 117 }
 118
 119 static int store_mbr(struct supertype *st, int fd)
 120 {
 121         struct MBR *old, *super;
 122
 123         if (posix_memalign((void**)&old, 512, 512) != 0) {
 124                 fprintf(stderr, Name ": %s could not allocate superblock\n",
 125                         __func__);
 126                 return 1;
 127         }
 128
 129         ioctl(fd, BLKFLSBUF, 0); /* make sure we read current data */
 130
 131         lseek(fd, 0, 0);
 132         if (read(fd, old, sizeof(*old)) != sizeof(*old)) {
 133                 free(old);
 134                 return 1;
 135         }
 136
 137         super = st->sb;
 138         memcpy(super->pad, old->pad, sizeof(super->pad));
 139         free(old);
 140         lseek(fd, 0, 0);
 141         if (write(fd, super, sizeof(*super)) != sizeof(*super))
 142                 return 4;
 143         fsync(fd);
 144         ioctl(fd, BLKRRPART, 0);
 145         return 0;
 146 }
 147
 148 static void getinfo_mbr(struct supertype *st, struct mdinfo *info, char *map)
 149 {
 150         struct MBR *sb = st->sb;
 151         int i;
 152
 153         memset(&info->array, 0, sizeof(info->array));
 154         memset(&info->disk, 0, sizeof(info->disk));
 155         strcpy(info->text_version, "mbr");
 156         strcpy(info->name, "mbr");
 157         info->component_size = 0;
 158
 159         for (i = 0; i < MBR_PARTITIONS ; i++)
 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 = malloc(sizeof(*st));
 173
 174         if (!st)
 175                 return st;
 176         if (strcmp(arg, "mbr") != 0)
 177                 return NULL;
 178
 179         st->ss = &mbr;
 180         st->info = NULL;
 181         st->minor_version = 0;
 182         st->max_devs = 1;
 183         st->sb = NULL;
 184         return st;
 185 }
 186
 187 #ifndef MDASSEMBLE
 188 static int validate_geometry(struct supertype *st, int level,
 189                              int layout, int raiddisks,
 190                              int chunk, unsigned long long size,
 191                              char *subdev, unsigned long long *freesize,
 192                              int verbose)
 193 {
 194         fprintf(stderr, Name ": mbr metadata cannot be used this way\n");
 195         return 0;
 196 }
 197 #endif
 198
 199 struct superswitch mbr = {
 200 #ifndef MDASSEMBLE
 201         .examine_super = examine_mbr,
 202 #endif
 203         .validate_geometry = validate_geometry,
 204         .match_metadata_desc = match_metadata_desc,
 205         .load_super = load_super_mbr,
 206         .store_super = store_mbr,
 207         .getinfo_super = getinfo_mbr,
 208         .free_super = free_mbr,
 209         .name = "mbr",
 210 };