git.oblomov.eu Git - linux-2.6/blob - fs/sysv/super.c

   1 /*
   2  *  linux/fs/sysv/inode.c
   3  *
   4  *  minix/inode.c
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  *
   7  *  xenix/inode.c
   8  *  Copyright (C) 1992  Doug Evans
   9  *
  10  *  coh/inode.c
  11  *  Copyright (C) 1993  Pascal Haible, Bruno Haible
  12  *
  13  *  sysv/inode.c
  14  *  Copyright (C) 1993  Paul B. Monday
  15  *
  16  *  sysv/inode.c
  17  *  Copyright (C) 1993  Bruno Haible
  18  *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
  19  *
  20  *  This file contains code for read/parsing the superblock.
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/init.h>
  25 #include <linux/slab.h>
  26 #include <linux/buffer_head.h>
  27 #include "sysv.h"
  28
  29 /*
  30  * The following functions try to recognize specific filesystems.
  31  *
  32  * We recognize:
  33  * - Xenix FS by its magic number.
  34  * - SystemV FS by its magic number.
  35  * - Coherent FS by its funny fname/fpack field.
  36  * - SCO AFS by s_nfree == 0xffff
  37  * - V7 FS has no distinguishing features.
  38  *
  39  * We discriminate among SystemV4 and SystemV2 FS by the assumption that
  40  * the time stamp is not < 01-01-1980.
  41  */
  42
  43 enum {
  44         JAN_1_1980 = (10*365 + 2) * 24 * 60 * 60
  45 };
  46
  47 static void detected_xenix(struct sysv_sb_info *sbi)
  48 {
  49         struct buffer_head *bh1 = sbi->s_bh1;
  50         struct buffer_head *bh2 = sbi->s_bh2;
  51         struct xenix_super_block * sbd1;
  52         struct xenix_super_block * sbd2;
  53
  54         if (bh1 != bh2)
  55                 sbd1 = sbd2 = (struct xenix_super_block *) bh1->b_data;
  56         else {
  57                 /* block size = 512, so bh1 != bh2 */
  58                 sbd1 = (struct xenix_super_block *) bh1->b_data;
  59                 sbd2 = (struct xenix_super_block *) (bh2->b_data - 512);
  60         }
  61
  62         sbi->s_link_max = XENIX_LINK_MAX;
  63         sbi->s_fic_size = XENIX_NICINOD;
  64         sbi->s_flc_size = XENIX_NICFREE;
  65         sbi->s_sbd1 = (char *)sbd1;
  66         sbi->s_sbd2 = (char *)sbd2;
  67         sbi->s_sb_fic_count = &sbd1->s_ninode;
  68         sbi->s_sb_fic_inodes = &sbd1->s_inode[0];
  69         sbi->s_sb_total_free_inodes = &sbd2->s_tinode;
  70         sbi->s_bcache_count = &sbd1->s_nfree;
  71         sbi->s_bcache = &sbd1->s_free[0];
  72         sbi->s_free_blocks = &sbd2->s_tfree;
  73         sbi->s_sb_time = &sbd2->s_time;
  74         sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd1->s_isize);
  75         sbi->s_nzones = fs32_to_cpu(sbi, sbd1->s_fsize);
  76 }
  77
  78 static void detected_sysv4(struct sysv_sb_info *sbi)
  79 {
  80         struct sysv4_super_block * sbd;
  81         struct buffer_head *bh1 = sbi->s_bh1;
  82         struct buffer_head *bh2 = sbi->s_bh2;
  83
  84         if (bh1 == bh2)
  85                 sbd = (struct sysv4_super_block *) (bh1->b_data + BLOCK_SIZE/2);
  86         else
  87                 sbd = (struct sysv4_super_block *) bh2->b_data;
  88
  89         sbi->s_link_max = SYSV_LINK_MAX;
  90         sbi->s_fic_size = SYSV_NICINOD;
  91         sbi->s_flc_size = SYSV_NICFREE;
  92         sbi->s_sbd1 = (char *)sbd;
  93         sbi->s_sbd2 = (char *)sbd;
  94         sbi->s_sb_fic_count = &sbd->s_ninode;
  95         sbi->s_sb_fic_inodes = &sbd->s_inode[0];
  96         sbi->s_sb_total_free_inodes = &sbd->s_tinode;
  97         sbi->s_bcache_count = &sbd->s_nfree;
  98         sbi->s_bcache = &sbd->s_free[0];
  99         sbi->s_free_blocks = &sbd->s_tfree;
 100         sbi->s_sb_time = &sbd->s_time;
 101         sbi->s_sb_state = &sbd->s_state;
 102         sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd->s_isize);
 103         sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize);
 104 }
 105
 106 static void detected_sysv2(struct sysv_sb_info *sbi)
 107 {
 108         struct sysv2_super_block *sbd;
 109         struct buffer_head *bh1 = sbi->s_bh1;
 110         struct buffer_head *bh2 = sbi->s_bh2;
 111
 112         if (bh1 == bh2)
 113                 sbd = (struct sysv2_super_block *) (bh1->b_data + BLOCK_SIZE/2);
 114         else
 115                 sbd = (struct sysv2_super_block *) bh2->b_data;
 116
 117         sbi->s_link_max = SYSV_LINK_MAX;
 118         sbi->s_fic_size = SYSV_NICINOD;
 119         sbi->s_flc_size = SYSV_NICFREE;
 120         sbi->s_sbd1 = (char *)sbd;
 121         sbi->s_sbd2 = (char *)sbd;
 122         sbi->s_sb_fic_count = &sbd->s_ninode;
 123         sbi->s_sb_fic_inodes = &sbd->s_inode[0];
 124         sbi->s_sb_total_free_inodes = &sbd->s_tinode;
 125         sbi->s_bcache_count = &sbd->s_nfree;
 126         sbi->s_bcache = &sbd->s_free[0];
 127         sbi->s_free_blocks = &sbd->s_tfree;
 128         sbi->s_sb_time = &sbd->s_time;
 129         sbi->s_sb_state = &sbd->s_state;
 130         sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd->s_isize);
 131         sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize);
 132 }
 133
 134 static void detected_coherent(struct sysv_sb_info *sbi)
 135 {
 136         struct coh_super_block * sbd;
 137         struct buffer_head *bh1 = sbi->s_bh1;
 138
 139         sbd = (struct coh_super_block *) bh1->b_data;
 140
 141         sbi->s_link_max = COH_LINK_MAX;
 142         sbi->s_fic_size = COH_NICINOD;
 143         sbi->s_flc_size = COH_NICFREE;
 144         sbi->s_sbd1 = (char *)sbd;
 145         sbi->s_sbd2 = (char *)sbd;
 146         sbi->s_sb_fic_count = &sbd->s_ninode;
 147         sbi->s_sb_fic_inodes = &sbd->s_inode[0];
 148         sbi->s_sb_total_free_inodes = &sbd->s_tinode;
 149         sbi->s_bcache_count = &sbd->s_nfree;
 150         sbi->s_bcache = &sbd->s_free[0];
 151         sbi->s_free_blocks = &sbd->s_tfree;
 152         sbi->s_sb_time = &sbd->s_time;
 153         sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd->s_isize);
 154         sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize);
 155 }
 156
 157 static void detected_v7(struct sysv_sb_info *sbi)
 158 {
 159         struct buffer_head *bh2 = sbi->s_bh2;
 160         struct v7_super_block *sbd = (struct v7_super_block *)bh2->b_data;
 161
 162         sbi->s_link_max = V7_LINK_MAX;
 163         sbi->s_fic_size = V7_NICINOD;
 164         sbi->s_flc_size = V7_NICFREE;
 165         sbi->s_sbd1 = (char *)sbd;
 166         sbi->s_sbd2 = (char *)sbd;
 167         sbi->s_sb_fic_count = &sbd->s_ninode;
 168         sbi->s_sb_fic_inodes = &sbd->s_inode[0];
 169         sbi->s_sb_total_free_inodes = &sbd->s_tinode;
 170         sbi->s_bcache_count = &sbd->s_nfree;
 171         sbi->s_bcache = &sbd->s_free[0];
 172         sbi->s_free_blocks = &sbd->s_tfree;
 173         sbi->s_sb_time = &sbd->s_time;
 174         sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd->s_isize);
 175         sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize);
 176 }
 177
 178 static int detect_xenix(struct sysv_sb_info *sbi, struct buffer_head *bh)
 179 {
 180         struct xenix_super_block *sbd = (struct xenix_super_block *)bh->b_data;
 181         if (*(__le32 *)&sbd->s_magic == cpu_to_le32(0x2b5544))
 182                 sbi->s_bytesex = BYTESEX_LE;
 183         else if (*(__be32 *)&sbd->s_magic == cpu_to_be32(0x2b5544))
 184                 sbi->s_bytesex = BYTESEX_BE;
 185         else
 186                 return 0;
 187         switch (fs32_to_cpu(sbi, sbd->s_type)) {
 188         case 1:
 189                 sbi->s_type = FSTYPE_XENIX;
 190                 return 1;
 191         case 2:
 192                 sbi->s_type = FSTYPE_XENIX;
 193                 return 2;
 194         default:
 195                 return 0;
 196         }
 197 }
 198
 199 static int detect_sysv(struct sysv_sb_info *sbi, struct buffer_head *bh)
 200 {
 201         struct super_block *sb = sbi->s_sb;
 202         /* All relevant fields are at the same offsets in R2 and R4 */
 203         struct sysv4_super_block * sbd;
 204         u32 type;
 205
 206         sbd = (struct sysv4_super_block *) (bh->b_data + BLOCK_SIZE/2);
 207         if (*(__le32 *)&sbd->s_magic == cpu_to_le32(0xfd187e20))
 208                 sbi->s_bytesex = BYTESEX_LE;
 209         else if (*(__be32 *)&sbd->s_magic == cpu_to_be32(0xfd187e20))
 210                 sbi->s_bytesex = BYTESEX_BE;
 211         else
 212                 return 0;
 213
 214         type = fs32_to_cpu(sbi, sbd->s_type);
 215
 216         if (fs16_to_cpu(sbi, sbd->s_nfree) == 0xffff) {
 217                 sbi->s_type = FSTYPE_AFS;
 218                 sbi->s_forced_ro = 1;
 219                 if (!(sb->s_flags & MS_RDONLY)) {
 220                         printk("SysV FS: SCO EAFS on %s detected, "
 221                                 "forcing read-only mode.\n",
 222                                 sb->s_id);
 223                 }
 224                 return type;
 225         }
 226
 227         if (fs32_to_cpu(sbi, sbd->s_time) < JAN_1_1980) {
 228                 /* this is likely to happen on SystemV2 FS */
 229                 if (type > 3 || type < 1)
 230                         return 0;
 231                 sbi->s_type = FSTYPE_SYSV2;
 232                 return type;
 233         }
 234         if ((type > 3 || type < 1) && (type > 0x30 || type < 0x10))
 235                 return 0;
 236
 237         /* On Interactive Unix (ISC) Version 4.0/3.x s_type field = 0x10,
 238            0x20 or 0x30 indicates that symbolic links and the 14-character
 239            filename limit is gone. Due to lack of information about this
 240            feature read-only mode seems to be a reasonable approach... -KGB */
 241
 242         if (type >= 0x10) {
 243                 printk("SysV FS: can't handle long file names on %s, "
 244                        "forcing read-only mode.\n", sb->s_id);
 245                 sbi->s_forced_ro = 1;
 246         }
 247
 248         sbi->s_type = FSTYPE_SYSV4;
 249         return type >= 0x10 ? type >> 4 : type;
 250 }
 251
 252 static int detect_coherent(struct sysv_sb_info *sbi, struct buffer_head *bh)
 253 {
 254         struct coh_super_block * sbd;
 255
 256         sbd = (struct coh_super_block *) (bh->b_data + BLOCK_SIZE/2);
 257         if ((memcmp(sbd->s_fname,"noname",6) && memcmp(sbd->s_fname,"xxxxx ",6))
 258             || (memcmp(sbd->s_fpack,"nopack",6) && memcmp(sbd->s_fpack,"xxxxx\n",6)))
 259                 return 0;
 260         sbi->s_bytesex = BYTESEX_PDP;
 261         sbi->s_type = FSTYPE_COH;
 262         return 1;
 263 }
 264
 265 static int detect_sysv_odd(struct sysv_sb_info *sbi, struct buffer_head *bh)
 266 {
 267         int size = detect_sysv(sbi, bh);
 268
 269         return size>2 ? 0 : size;
 270 }
 271
 272 static struct {
 273         int block;
 274         int (*test)(struct sysv_sb_info *, struct buffer_head *);
 275 } flavours[] = {
 276         {1, detect_xenix},
 277         {0, detect_sysv},
 278         {0, detect_coherent},
 279         {9, detect_sysv_odd},
 280         {15,detect_sysv_odd},
 281         {18,detect_sysv},
 282 };
 283
 284 static char *flavour_names[] = {
 285         [FSTYPE_XENIX]  = "Xenix",
 286         [FSTYPE_SYSV4]  = "SystemV",
 287         [FSTYPE_SYSV2]  = "SystemV Release 2",
 288         [FSTYPE_COH]    = "Coherent",
 289         [FSTYPE_V7]     = "V7",
 290         [FSTYPE_AFS]    = "AFS",
 291 };
 292
 293 static void (*flavour_setup[])(struct sysv_sb_info *) = {
 294         [FSTYPE_XENIX]  = detected_xenix,
 295         [FSTYPE_SYSV4]  = detected_sysv4,
 296         [FSTYPE_SYSV2]  = detected_sysv2,
 297         [FSTYPE_COH]    = detected_coherent,
 298         [FSTYPE_V7]     = detected_v7,
 299         [FSTYPE_AFS]    = detected_sysv4,
 300 };
 301
 302 static int complete_read_super(struct super_block *sb, int silent, int size)
 303 {
 304         struct sysv_sb_info *sbi = SYSV_SB(sb);
 305         struct inode *root_inode;
 306         char *found = flavour_names[sbi->s_type];
 307         u_char n_bits = size+8;
 308         int bsize = 1 << n_bits;
 309         int bsize_4 = bsize >> 2;
 310
 311         sbi->s_firstinodezone = 2;
 312
 313         flavour_setup[sbi->s_type](sbi);
 314
 315         sbi->s_truncate = 1;
 316         sbi->s_ndatazones = sbi->s_nzones - sbi->s_firstdatazone;
 317         sbi->s_inodes_per_block = bsize >> 6;
 318         sbi->s_inodes_per_block_1 = (bsize >> 6)-1;
 319         sbi->s_inodes_per_block_bits = n_bits-6;
 320         sbi->s_ind_per_block = bsize_4;
 321         sbi->s_ind_per_block_2 = bsize_4*bsize_4;
 322         sbi->s_toobig_block = 10 + bsize_4 * (1 + bsize_4 * (1 + bsize_4));
 323         sbi->s_ind_per_block_bits = n_bits-2;
 324
 325         sbi->s_ninodes = (sbi->s_firstdatazone - sbi->s_firstinodezone)
 326                 << sbi->s_inodes_per_block_bits;
 327
 328         if (!silent)
 329                 printk("VFS: Found a %s FS (block size = %ld) on device %s\n",
 330                        found, sb->s_blocksize, sb->s_id);
 331
 332         sb->s_magic = SYSV_MAGIC_BASE + sbi->s_type;
 333         /* set up enough so that it can read an inode */
 334         sb->s_op = &sysv_sops;
 335         root_inode = iget(sb,SYSV_ROOT_INO);
 336         if (!root_inode || is_bad_inode(root_inode)) {
 337                 printk("SysV FS: get root inode failed\n");
 338                 return 0;
 339         }
 340         sb->s_root = d_alloc_root(root_inode);
 341         if (!sb->s_root) {
 342                 iput(root_inode);
 343                 printk("SysV FS: get root dentry failed\n");
 344                 return 0;
 345         }
 346         if (sbi->s_forced_ro)
 347                 sb->s_flags |= MS_RDONLY;
 348         if (sbi->s_truncate)
 349                 sb->s_root->d_op = &sysv_dentry_operations;
 350         sb->s_dirt = 1;
 351         return 1;
 352 }
 353
 354 static int sysv_fill_super(struct super_block *sb, void *data, int silent)
 355 {
 356         struct buffer_head *bh1, *bh = NULL;
 357         struct sysv_sb_info *sbi;
 358         unsigned long blocknr;
 359         int size = 0, i;
 360
 361         BUILD_BUG_ON(1024 != sizeof (struct xenix_super_block));
 362         BUILD_BUG_ON(512 != sizeof (struct sysv4_super_block));
 363         BUILD_BUG_ON(512 != sizeof (struct sysv2_super_block));
 364         BUILD_BUG_ON(500 != sizeof (struct coh_super_block));
 365         BUILD_BUG_ON(64 != sizeof (struct sysv_inode));
 366
 367         sbi = kzalloc(sizeof(struct sysv_sb_info), GFP_KERNEL);
 368         if (!sbi)
 369                 return -ENOMEM;
 370
 371         sbi->s_sb = sb;
 372         sbi->s_block_base = 0;
 373         sb->s_fs_info = sbi;
 374
 375         sb_set_blocksize(sb, BLOCK_SIZE);
 376
 377         for (i = 0; i < ARRAY_SIZE(flavours) && !size; i++) {
 378                 brelse(bh);
 379                 bh = sb_bread(sb, flavours[i].block);
 380                 if (!bh)
 381                         continue;
 382                 size = flavours[i].test(SYSV_SB(sb), bh);
 383         }
 384
 385         if (!size)
 386                 goto Eunknown;
 387
 388         switch (size) {
 389                 case 1:
 390                         blocknr = bh->b_blocknr << 1;
 391                         brelse(bh);
 392                         sb_set_blocksize(sb, 512);
 393                         bh1 = sb_bread(sb, blocknr);
 394                         bh = sb_bread(sb, blocknr + 1);
 395                         break;
 396                 case 2:
 397                         bh1 = bh;
 398                         break;
 399                 case 3:
 400                         blocknr = bh->b_blocknr >> 1;
 401                         brelse(bh);
 402                         sb_set_blocksize(sb, 2048);
 403                         bh1 = bh = sb_bread(sb, blocknr);
 404                         break;
 405                 default:
 406                         goto Ebadsize;
 407         }
 408
 409         if (bh && bh1) {
 410                 sbi->s_bh1 = bh1;
 411                 sbi->s_bh2 = bh;
 412                 if (complete_read_super(sb, silent, size))
 413                         return 0;
 414         }
 415
 416         brelse(bh1);
 417         brelse(bh);
 418         sb_set_blocksize(sb, BLOCK_SIZE);
 419         printk("oldfs: cannot read superblock\n");
 420 failed:
 421         kfree(sbi);
 422         return -EINVAL;
 423
 424 Eunknown:
 425         brelse(bh);
 426         if (!silent)
 427                 printk("VFS: unable to find oldfs superblock on device %s\n",
 428                         sb->s_id);
 429         goto failed;
 430 Ebadsize:
 431         brelse(bh);
 432         if (!silent)
 433                 printk("VFS: oldfs: unsupported block size (%dKb)\n",
 434                         1<<(size-2));
 435         goto failed;
 436 }
 437
 438 static int v7_fill_super(struct super_block *sb, void *data, int silent)
 439 {
 440         struct sysv_sb_info *sbi;
 441         struct buffer_head *bh, *bh2 = NULL;
 442         struct v7_super_block *v7sb;
 443         struct sysv_inode *v7i;
 444
 445         if (440 != sizeof (struct v7_super_block))
 446                 panic("V7 FS: bad super-block size");
 447         if (64 != sizeof (struct sysv_inode))
 448                 panic("sysv fs: bad i-node size");
 449
 450         sbi = kzalloc(sizeof(struct sysv_sb_info), GFP_KERNEL);
 451         if (!sbi)
 452                 return -ENOMEM;
 453
 454         sbi->s_sb = sb;
 455         sbi->s_block_base = 0;
 456         sbi->s_type = FSTYPE_V7;
 457         sbi->s_bytesex = BYTESEX_PDP;
 458         sb->s_fs_info = sbi;
 459
 460         sb_set_blocksize(sb, 512);
 461
 462         if ((bh = sb_bread(sb, 1)) == NULL) {
 463                 if (!silent)
 464                         printk("VFS: unable to read V7 FS superblock on "
 465                                "device %s.\n", sb->s_id);
 466                 goto failed;
 467         }
 468
 469         /* plausibility check on superblock */
 470         v7sb = (struct v7_super_block *) bh->b_data;
 471         if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
 472             fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
 473             fs32_to_cpu(sbi, v7sb->s_time) == 0)
 474                 goto failed;
 475
 476         /* plausibility check on root inode: it is a directory,
 477            with a nonzero size that is a multiple of 16 */
 478         if ((bh2 = sb_bread(sb, 2)) == NULL)
 479                 goto failed;
 480         v7i = (struct sysv_inode *)(bh2->b_data + 64);
 481         if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
 482             (fs32_to_cpu(sbi, v7i->i_size) == 0) ||
 483             (fs32_to_cpu(sbi, v7i->i_size) & 017) != 0)
 484                 goto failed;
 485         brelse(bh2);
 486         bh2 = NULL;
 487
 488         sbi->s_bh1 = bh;
 489         sbi->s_bh2 = bh;
 490         if (complete_read_super(sb, silent, 1))
 491                 return 0;
 492
 493 failed:
 494         brelse(bh2);
 495         brelse(bh);
 496         kfree(sbi);
 497         return -EINVAL;
 498 }
 499
 500 /* Every kernel module contains stuff like this. */
 501
 502 static int sysv_get_sb(struct file_system_type *fs_type,
 503         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 504 {
 505         return get_sb_bdev(fs_type, flags, dev_name, data, sysv_fill_super,
 506                            mnt);
 507 }
 508
 509 static int v7_get_sb(struct file_system_type *fs_type,
 510         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 511 {
 512         return get_sb_bdev(fs_type, flags, dev_name, data, v7_fill_super, mnt);
 513 }
 514
 515 static struct file_system_type sysv_fs_type = {
 516         .owner          = THIS_MODULE,
 517         .name           = "sysv",
 518         .get_sb         = sysv_get_sb,
 519         .kill_sb        = kill_block_super,
 520         .fs_flags       = FS_REQUIRES_DEV,
 521 };
 522
 523 static struct file_system_type v7_fs_type = {
 524         .owner          = THIS_MODULE,
 525         .name           = "v7",
 526         .get_sb         = v7_get_sb,
 527         .kill_sb        = kill_block_super,
 528         .fs_flags       = FS_REQUIRES_DEV,
 529 };
 530
 531 static int __init init_sysv_fs(void)
 532 {
 533         int error;
 534
 535         error = sysv_init_icache();
 536         if (error)
 537                 goto out;
 538         error = register_filesystem(&sysv_fs_type);
 539         if (error)
 540                 goto destroy_icache;
 541         error = register_filesystem(&v7_fs_type);
 542         if (error)
 543                 goto unregister;
 544         return 0;
 545
 546 unregister:
 547         unregister_filesystem(&sysv_fs_type);
 548 destroy_icache:
 549         sysv_destroy_icache();
 550 out:
 551         return error;
 552 }
 553
 554 static void __exit exit_sysv_fs(void)
 555 {
 556         unregister_filesystem(&sysv_fs_type);
 557         unregister_filesystem(&v7_fs_type);
 558         sysv_destroy_icache();
 559 }
 560
 561 module_init(init_sysv_fs)
 562 module_exit(exit_sysv_fs)
 563 MODULE_LICENSE("GPL");