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                 pr_err("could not allocate superblock\n");
  85                 return 1;
  86         }
  87
  88         lseek(fd, 0, 0);
  89         if (read(fd, super, sizeof(*super)) != sizeof(*super)) {
  90                 if (devname)
  91                         pr_err("Cannot read partition table on %s\n",
  92                                 devname);
  93                 free(super);
  94                 return 1;
  95         }
  96
  97         if (super->magic != MBR_SIGNATURE_MAGIC) {
  98                 if (devname)
  99                         pr_err("No partition table found on %s\n",
 100                                 devname);
 101                 free(super);
 102                 return 1;
 103         }
 104
 105         st->sb = super;
 106
 107         if (st->ss == NULL) {
 108                 st->ss = &mbr;
 109                 st->minor_version = 0;
 110                 st->max_devs = 1;
 111                 st->info = NULL;
 112         }
 113         return 0;
 114 }
 115
 116 static int store_mbr(struct supertype *st, int fd)
 117 {
 118         struct MBR *old, *super;
 119
 120         if (posix_memalign((void**)&old, 512, 512) != 0) {
 121                 pr_err("could not allocate superblock\n");
 122                 return 1;
 123         }
 124
 125         lseek(fd, 0, 0);
 126         if (read(fd, old, sizeof(*old)) != sizeof(*old)) {
 127                 free(old);
 128                 return 1;
 129         }
 130
 131         super = st->sb;
 132         memcpy(super->pad, old->pad, sizeof(super->pad));
 133         free(old);
 134         lseek(fd, 0, 0);
 135         if (write(fd, super, sizeof(*super)) != sizeof(*super))
 136                 return 4;
 137         fsync(fd);
 138         ioctl(fd, BLKRRPART, 0);
 139         return 0;
 140 }
 141
 142 static void getinfo_mbr(struct supertype *st, struct mdinfo *info, char *map)
 143 {
 144         struct MBR *sb = st->sb;
 145         int i;
 146
 147         memset(&info->array, 0, sizeof(info->array));
 148         memset(&info->disk, 0, sizeof(info->disk));
 149         strcpy(info->text_version, "mbr");
 150         strcpy(info->name, "mbr");
 151         info->component_size = 0;
 152
 153         for (i = 0; i < MBR_PARTITIONS ; i++)
 154                 if (sb->parts[i].blocks_num) {
 155                         unsigned long last =
 156                                 (unsigned long)__le32_to_cpu(sb->parts[i].blocks_num)
 157                                 + (unsigned long)__le32_to_cpu(sb->parts[i].first_sect_lba);
 158                         if (last > info->component_size)
 159                                 info->component_size = last;
 160                 }
 161
 162 }
 163
 164 static struct supertype *match_metadata_desc(char *arg)
 165 {
 166         struct supertype *st;
 167
 168         if (strcmp(arg, "mbr") != 0)
 169                 return NULL;
 170
 171         st = xmalloc(sizeof(*st));
 172         st->ss = &mbr;
 173         st->info = NULL;
 174         st->minor_version = 0;
 175         st->max_devs = 1;
 176         st->sb = NULL;
 177         return st;
 178 }
 179
 180 #ifndef MDASSEMBLE
 181 static int validate_geometry(struct supertype *st, int level,
 182                              int layout, int raiddisks,
 183                              int *chunk, unsigned long long size,
 184                              unsigned long long data_offset,
 185                              char *subdev, unsigned long long *freesize,
 186                              int verbose)
 187 {
 188         pr_err("mbr metadata cannot be used this way\n");
 189         return 0;
 190 }
 191 #endif
 192
 193 struct superswitch mbr = {
 194 #ifndef MDASSEMBLE
 195         .examine_super = examine_mbr,
 196         .validate_geometry = validate_geometry,
 197 #endif
 198         .match_metadata_desc = match_metadata_desc,
 199         .load_super = load_super_mbr,
 200         .store_super = store_mbr,
 201         .getinfo_super = getinfo_mbr,
 202         .free_super = free_mbr,
 203         .name = "mbr",
 204 };