mdopen.c

   1 /*
   2  * mdadm - manage Linux "md" devices aka RAID arrays.
   3  *
   4  * Copyright (C) 2001-2006 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: <neilb@cse.unsw.edu.au>
  23  *    Paper: Neil Brown
  24  *           School of Computer Science and Engineering
  25  *           The University of New South Wales
  26  *           Sydney, 2052
  27  *           Australia
  28  */
  29
  30 #include "mdadm.h"
  31 #include "md_p.h"
  32 #include <ctype.h>
  33
  34
  35 void make_dev_symlink(char *dev)
  36 {
  37         char *new = strdup(dev);
  38
  39         if (!new) return;
  40         /* /dev/md/0 -> /dev/md0
  41          * /dev/md/d0 -> /dev/md_d0
  42          */
  43         if (isdigit(new[8]))
  44                 strcpy(new+7, new+8);
  45         else
  46                 new[7] = '_';
  47         if (symlink(dev+5, new))
  48                 perror(new);
  49 }
  50
  51
  52 void make_parts(char *dev, int cnt, int symlinks)
  53 {
  54         /* make 'cnt' partition devices for 'dev'
  55          * We use the major/minor from dev and add 1..cnt
  56          * If dev ends with a digit, we add "p%d" else "%d"
  57          * If the name exists, we use it's owner/mode,
  58          * else that of dev
  59          */
  60         struct stat stb;
  61         int major, minor;
  62         int i;
  63         int nlen = strlen(dev) + 20;
  64         char *name = malloc(nlen);
  65         int dig = isdigit(dev[strlen(dev)-1]);
  66
  67         if (cnt==0) cnt=4;
  68         if (stat(dev, &stb)!= 0)
  69                 return;
  70         if (!S_ISBLK(stb.st_mode))
  71                 return;
  72         major = major(stb.st_rdev);
  73         minor = minor(stb.st_rdev);
  74         for (i=1; i <= cnt ; i++) {
  75                 struct stat stb2;
  76                 snprintf(name, nlen, "%s%s%d", dev, dig?"p":"", i);
  77                 if (stat(name, &stb2)==0) {
  78                         if (!S_ISBLK(stb2.st_mode))
  79                                 continue;
  80                         if (stb2.st_rdev == makedev(major, minor+i))
  81                                 continue;
  82                         unlink(name);
  83                 } else {
  84                         stb2 = stb;
  85                 }
  86                 if (mknod(name, S_IFBLK | 0600, makedev(major, minor+i)))
  87                         perror("mknod");
  88                 if (chown(name, stb2.st_uid, stb2.st_gid))
  89                         perror("chown");
  90                 if (chmod(name, stb2.st_mode & 07777))
  91                         perror("chmod");
  92                 if (symlinks && strncmp(name, "/dev/md/", 8) == 0)
  93                         make_dev_symlink(name);
  94                 stat(name, &stb2);
  95                 add_dev(name, &stb2, 0, NULL);
  96         }
  97 }
  98
  99
 100 /*
 101  * Open a given md device, and check that it really is one.
 102  * If 'autof' is given, then we need to create, or recreate, the md device.
 103  * If the name already exists, and is not a block device, we fail.
 104  * If it exists and is not an md device, is not the right type (partitioned or not),
 105  * or is currently in-use, we remove the device, but remember the owner and mode.
 106  * If it now doesn't exist, we find a new md array and create the device.
 107  * Default ownership/mode comes from config file.
 108  */
 109 int open_mddev(char *dev, int autof)
 110 {
 111         int mdfd;
 112         struct stat stb;
 113         int major = MD_MAJOR;
 114         int minor = 0;
 115         int must_remove = 0;
 116         struct mdstat_ent *mdlist;
 117         int num;
 118         struct createinfo *ci = conf_get_create_info();
 119         int parts;
 120
 121         if (autof == 0)
 122                 autof = ci->autof;
 123
 124         parts = autof >> 3;
 125         autof &= 7;
 126
 127         if (autof && autof != 1) {
 128                 /* autof is set, so we need to check that the name is ok,
 129                  * and possibly create one if not
 130                  */
 131                 int std;
 132                 stb.st_mode = 0;
 133                 if (stat(dev, &stb)==0 && ! S_ISBLK(stb.st_mode)) {
 134                         fprintf(stderr, Name ": %s is not a block device.\n",
 135                                 dev);
 136                         return -1;
 137                 }
 138                 if (autof == 2 && stb.st_mode == 0 && !is_standard(dev, NULL)) {
 139                         fprintf(stderr, Name ": --auto=yes requires a 'standard' md device name, not %s\n", dev);
 140                         return -1;
 141                 }
 142                 /* check major number is correct */
 143                 num = -1;
 144                 std = is_standard(dev, &num);
 145                 if (std>0) major = get_mdp_major();
 146                 switch(autof) {
 147                 case 2: /* only create is_standard names */
 148                         if (!std && !stb.st_mode) {
 149                                 fprintf(stderr, Name ": --auto=yes requires a 'standard' md device name, not %s\n", dev);
 150                                 return -1;
 151                         }
 152                         break;
 153                 case 3: /* create md, reject std>0 */
 154                         if (std > 0) {
 155                                 fprintf(stderr, Name ": that --auto option not compatable with device named %s\n", dev);
 156                                 return -1;
 157                         }
 158                         break;
 159                 case 4: /* create mdp, reject std<0 */
 160                         if (std < 0) {
 161                                 fprintf(stderr, Name ": that --auto option not compatable with device named %s\n", dev);
 162                                 return -1;
 163                         }
 164                         break;
 165                 case 5: /* default to md if not standard */
 166                         break;
 167                 case 6: /* default to mdp if not standard */
 168                         if (std == 0) major = get_mdp_major();
 169                         break;
 170                 }
 171                 /* major is final. num is -1 if not standard */
 172                 if (stb.st_mode && major(stb.st_rdev) != major)
 173                         must_remove = 1;
 174                 if (stb.st_mode && !must_remove) {
 175                         /* looks ok, see if it is available */
 176                         mdfd = open(dev, O_RDWR, 0);
 177                         if (mdfd < 0) {
 178                                 fprintf(stderr, Name ": error opening %s: %s\n",
 179                                         dev, strerror(errno));
 180                                 return -1;
 181                         } else if (md_get_version(mdfd) <= 0) {
 182                                 fprintf(stderr, Name ": %s does not appear to be an md device\n",
 183                                         dev);
 184                                 close(mdfd);
 185                                 return -1;
 186                         }
 187                         if (major != MD_MAJOR && parts > 0)
 188                                 make_parts(dev, parts, ci->symlinks);
 189                         return mdfd;
 190                 }
 191                 /* Ok, need to find a minor that is not in use.
 192                  * If the device name is in a 'standard' format,
 193                  * intuit the minor from that, else
 194                  * easiest to read /proc/mdstat, and hunt through for
 195                  * an unused number
 196                  */
 197                 if (num < 0) {
 198                         /* need to pick an unused number */
 199                         mdlist = mdstat_read(0, 0);
 200                         /* Choose a large number.  Start from 127 and search down,
 201                          * but if nothing is found, start really big
 202                          */
 203                         for (num = 127 ; num != 128 ; num = num ? num-1 : (1<<22)-1) {
 204                                 struct mdstat_ent *me;
 205                                 int devnum = num;
 206                                 if (major != MD_MAJOR)
 207                                         devnum = -1-num;
 208
 209                                 for (me=mdlist; me; me=me->next)
 210                                         if (me->devnum == devnum)
 211                                                 break;
 212                                 if (!me) {
 213                                         /* doesn't exist in mdstat.
 214                                          * make sure it is new to /dev too
 215                                          */
 216                                         char *dn;
 217                                         if (major != MD_MAJOR)
 218                                                 minor = num << MdpMinorShift;
 219                                         else
 220                                                 minor = num;
 221                                         dn = map_dev(major,minor, 0);
 222                                         if (dn==NULL || is_standard(dn, NULL)) {
 223                                                 /* this number only used by a 'standard' name,
 224                                                  * so it is safe to use
 225                                                  */
 226                                                 break;
 227                                         }
 228                                 }
 229                         }
 230                 } else if (major == MD_MAJOR)
 231                         minor = num;
 232                 else
 233                         minor = num << MdpMinorShift;
 234                 /* major and minor have been chosen */
 235
 236                 /* If it was a 'standard' name and it is in-use, then
 237                  * the device could already be correct
 238                  */
 239                 if (stb.st_mode && major(stb.st_rdev) == major &&
 240                     minor(stb.st_rdev) == minor)
 241                         ;
 242                 else {
 243                         if (major(makedev(major,minor)) != major ||
 244                             minor(makedev(major,minor)) != minor) {
 245                                 fprintf(stderr, Name ": Need newer C library to use more than 4 partitionable md devices, sorry\n");
 246                                 return -1;
 247                         }
 248                         if (must_remove)
 249                                 unlink(dev);
 250
 251                         if (strncmp(dev, "/dev/md/", 8) == 0) {
 252                                 if (mkdir("/dev/md",0700)==0) {
 253                                         if (chown("/dev/md", ci->uid, ci->gid))
 254                                                 perror("chown /dev/md");
 255                                         if (chmod("/dev/md", ci->mode| ((ci->mode>>2) & 0111)))
 256                                                 perror("chmod /dev/md");
 257                                 }
 258                         }
 259                         if (mknod(dev, S_IFBLK|0600, makedev(major, minor))!= 0) {
 260                                 fprintf(stderr, Name ": failed to create %s\n", dev);
 261                                 return -1;
 262                         }
 263                         if (must_remove) {
 264                                 if (chown(dev, stb.st_uid, stb.st_gid))
 265                                         perror("chown");
 266                                 if (chmod(dev, stb.st_mode & 07777))
 267                                         perror("chmod");
 268                         } else {
 269                                 if (chown(dev, ci->uid, ci->gid))
 270                                         perror("chown");
 271                                 if (chmod(dev, ci->mode))
 272                                         perror("chmod");
 273                         }
 274                         stat(dev, &stb);
 275                         add_dev(dev, &stb, 0, NULL);
 276                         if (ci->symlinks && strncmp(dev, "/dev/md/", 8) == 0)
 277                                 make_dev_symlink(dev);
 278                         if (major != MD_MAJOR)
 279                                 make_parts(dev,parts, ci->symlinks);
 280                 }
 281         }
 282         mdfd = open(dev, O_RDWR, 0);
 283         if (mdfd < 0)
 284                 fprintf(stderr, Name ": error opening %s: %s\n",
 285                         dev, strerror(errno));
 286         else if (md_get_version(mdfd) <= 0) {
 287                 fprintf(stderr, Name ": %s does not appear to be an md device\n",
 288                         dev);
 289                 close(mdfd);
 290                 mdfd = -1;
 291         }
 292         return mdfd;
 293 }
 294