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 (sbd->s_magic == cpu_to_le32(0x2b5544))
 182                 sbi->s_bytesex = BYTESEX_LE;
 183         else if (sbd->s_magic == cpu_to_be32(0x2b5544))
 184                 sbi->s_bytesex = BYTESEX_BE;
 185         else
 186                 return 0;
 187         if (sbd->s_type > 2 || sbd->s_type < 1)
 188                 return 0;
 189         sbi->s_type = FSTYPE_XENIX;
 190         return sbd->s_type;
 191 }
 192
 193 static int detect_sysv(struct sysv_sb_info *sbi, struct buffer_head *bh)
 194 {
 195         struct super_block *sb = sbi->s_sb;
 196         /* All relevant fields are at the same offsets in R2 and R4 */
 197         struct sysv4_super_block * sbd;
 198
 199         sbd = (struct sysv4_super_block *) (bh->b_data + BLOCK_SIZE/2);
 200         if (sbd->s_magic == cpu_to_le32(0xfd187e20))
 201                 sbi->s_bytesex = BYTESEX_LE;
 202         else if (sbd->s_magic == cpu_to_be32(0xfd187e20))
 203                 sbi->s_bytesex = BYTESEX_BE;
 204         else
 205                 return 0;
 206
 207         if (fs16_to_cpu(sbi, sbd->s_nfree) == 0xffff) {
 208                 sbi->s_type = FSTYPE_AFS;
 209                 sbi->s_forced_ro = 1;
 210                 if (!(sb->s_flags & MS_RDONLY)) {
 211                         printk("SysV FS: SCO EAFS on %s detected, "
 212                                 "forcing read-only mode.\n",
 213                                 sb->s_id);
 214                 }
 215                 return sbd->s_type;
 216         }
 217
 218         if (fs32_to_cpu(sbi, sbd->s_time) < JAN_1_1980) {
 219                 /* this is likely to happen on SystemV2 FS */
 220                 if (sbd->s_type > 3 || sbd->s_type < 1)
 221                         return 0;
 222                 sbi->s_type = FSTYPE_SYSV2;
 223                 return sbd->s_type;
 224         }
 225         if ((sbd->s_type > 3 || sbd->s_type < 1) &&
 226             (sbd->s_type > 0x30 || sbd->s_type < 0x10))
 227                 return 0;
 228
 229         /* On Interactive Unix (ISC) Version 4.0/3.x s_type field = 0x10,
 230            0x20 or 0x30 indicates that symbolic links and the 14-character
 231            filename limit is gone. Due to lack of information about this
 232            feature read-only mode seems to be a reasonable approach... -KGB */
 233
 234         if (sbd->s_type >= 0x10) {
 235                 printk("SysV FS: can't handle long file names on %s, "
 236                        "forcing read-only mode.\n", sb->s_id);
 237                 sbi->s_forced_ro = 1;
 238         }
 239
 240         sbi->s_type = FSTYPE_SYSV4;
 241         return sbd->s_type >= 0x10 ? (sbd->s_type >> 4) : sbd->s_type;
 242 }
 243
 244 static int detect_coherent(struct sysv_sb_info *sbi, struct buffer_head *bh)
 245 {
 246         struct coh_super_block * sbd;
 247
 248         sbd = (struct coh_super_block *) (bh->b_data + BLOCK_SIZE/2);
 249         if ((memcmp(sbd->s_fname,"noname",6) && memcmp(sbd->s_fname,"xxxxx ",6))
 250             || (memcmp(sbd->s_fpack,"nopack",6) && memcmp(sbd->s_fpack,"xxxxx\n",6)))
 251                 return 0;
 252         sbi->s_bytesex = BYTESEX_PDP;
 253         sbi->s_type = FSTYPE_COH;
 254         return 1;
 255 }
 256
 257 static int detect_sysv_odd(struct sysv_sb_info *sbi, struct buffer_head *bh)
 258 {
 259         int size = detect_sysv(sbi, bh);
 260
 261         return size>2 ? 0 : size;
 262 }
 263
 264 static struct {
 265         int block;
 266         int (*test)(struct sysv_sb_info *, struct buffer_head *);
 267 } flavours[] = {
 268         {1, detect_xenix},
 269         {0, detect_sysv},
 270         {0, detect_coherent},
 271         {9, detect_sysv_odd},
 272         {15,detect_sysv_odd},
 273         {18,detect_sysv},
 274 };
 275
 276 static char *flavour_names[] = {
 277         [FSTYPE_XENIX]  = "Xenix",
 278         [FSTYPE_SYSV4]  = "SystemV",
 279         [FSTYPE_SYSV2]  = "SystemV Release 2",
 280         [FSTYPE_COH]    = "Coherent",
 281         [FSTYPE_V7]     = "V7",
 282         [FSTYPE_AFS]    = "AFS",
 283 };
 284
 285 static void (*flavour_setup[])(struct sysv_sb_info *) = {
 286         [FSTYPE_XENIX]  = detected_xenix,
 287         [FSTYPE_SYSV4]  = detected_sysv4,
 288         [FSTYPE_SYSV2]  = detected_sysv2,
 289         [FSTYPE_COH]    = detected_coherent,
 290         [FSTYPE_V7]     = detected_v7,
 291         [FSTYPE_AFS]    = detected_sysv4,
 292 };
 293
 294 static int complete_read_super(struct super_block *sb, int silent, int size)
 295 {
 296         struct sysv_sb_info *sbi = SYSV_SB(sb);
 297         struct inode *root_inode;
 298         char *found = flavour_names[sbi->s_type];
 299         u_char n_bits = size+8;
 300         int bsize = 1 << n_bits;
 301         int bsize_4 = bsize >> 2;
 302
 303         sbi->s_firstinodezone = 2;
 304
 305         flavour_setup[sbi->s_type](sbi);
 306
 307         sbi->s_truncate = 1;
 308         sbi->s_ndatazones = sbi->s_nzones - sbi->s_firstdatazone;
 309         sbi->s_inodes_per_block = bsize >> 6;
 310         sbi->s_inodes_per_block_1 = (bsize >> 6)-1;
 311         sbi->s_inodes_per_block_bits = n_bits-6;
 312         sbi->s_ind_per_block = bsize_4;
 313         sbi->s_ind_per_block_2 = bsize_4*bsize_4;
 314         sbi->s_toobig_block = 10 + bsize_4 * (1 + bsize_4 * (1 + bsize_4));
 315         sbi->s_ind_per_block_bits = n_bits-2;
 316
 317         sbi->s_ninodes = (sbi->s_firstdatazone - sbi->s_firstinodezone)
 318                 << sbi->s_inodes_per_block_bits;
 319
 320         if (!silent)
 321                 printk("VFS: Found a %s FS (block size = %ld) on device %s\n",
 322                        found, sb->s_blocksize, sb->s_id);
 323
 324         sb->s_magic = SYSV_MAGIC_BASE + sbi->s_type;
 325         /* set up enough so that it can read an inode */
 326         sb->s_op = &sysv_sops;
 327         root_inode = iget(sb,SYSV_ROOT_INO);
 328         if (!root_inode || is_bad_inode(root_inode)) {
 329                 printk("SysV FS: get root inode failed\n");
 330                 return 0;
 331         }
 332         sb->s_root = d_alloc_root(root_inode);
 333         if (!sb->s_root) {
 334                 iput(root_inode);
 335                 printk("SysV FS: get root dentry failed\n");
 336                 return 0;
 337         }
 338         if (sbi->s_forced_ro)
 339                 sb->s_flags |= MS_RDONLY;
 340         if (sbi->s_truncate)
 341                 sb->s_root->d_op = &sysv_dentry_operations;
 342         sb->s_dirt = 1;
 343         return 1;
 344 }
 345
 346 static int sysv_fill_super(struct super_block *sb, void *data, int silent)
 347 {
 348         struct buffer_head *bh1, *bh = NULL;
 349         struct sysv_sb_info *sbi;
 350         unsigned long blocknr;
 351         int size = 0, i;
 352
 353         if (1024 != sizeof (struct xenix_super_block))
 354                 panic("Xenix FS: bad superblock size");
 355         if (512 != sizeof (struct sysv4_super_block))
 356                 panic("SystemV FS: bad superblock size");
 357         if (512 != sizeof (struct sysv2_super_block))
 358                 panic("SystemV FS: bad superblock size");
 359         if (500 != sizeof (struct coh_super_block))
 360                 panic("Coherent FS: bad superblock size");
 361         if (64 != sizeof (struct sysv_inode))
 362                 panic("sysv fs: bad inode size");
 363
 364         sbi = kmalloc(sizeof(struct sysv_sb_info), GFP_KERNEL);
 365         if (!sbi)
 366                 return -ENOMEM;
 367         memset(sbi, 0, sizeof(struct sysv_sb_info));
 368
 369         sbi->s_sb = sb;
 370         sbi->s_block_base = 0;
 371         sb->s_fs_info = sbi;
 372
 373         sb_set_blocksize(sb, BLOCK_SIZE);
 374
 375         for (i = 0; i < sizeof(flavours)/sizeof(flavours[0]) && !size; i++) {
 376                 brelse(bh);
 377                 bh = sb_bread(sb, flavours[i].block);
 378                 if (!bh)
 379                         continue;
 380                 size = flavours[i].test(SYSV_SB(sb), bh);
 381         }
 382
 383         if (!size)
 384                 goto Eunknown;
 385
 386         switch (size) {
 387                 case 1:
 388                         blocknr = bh->b_blocknr << 1;
 389                         brelse(bh);
 390                         sb_set_blocksize(sb, 512);
 391                         bh1 = sb_bread(sb, blocknr);
 392                         bh = sb_bread(sb, blocknr + 1);
 393                         break;
 394                 case 2:
 395                         bh1 = bh;
 396                         break;
 397                 case 3:
 398                         blocknr = bh->b_blocknr >> 1;
 399                         brelse(bh);
 400                         sb_set_blocksize(sb, 2048);
 401                         bh1 = bh = sb_bread(sb, blocknr);
 402                         break;
 403                 default:
 404                         goto Ebadsize;
 405         }
 406
 407         if (bh && bh1) {
 408                 sbi->s_bh1 = bh1;
 409                 sbi->s_bh2 = bh;
 410                 if (complete_read_super(sb, silent, size))
 411                         return 0;
 412         }
 413
 414         brelse(bh1);
 415         brelse(bh);
 416         sb_set_blocksize(sb, BLOCK_SIZE);
 417         printk("oldfs: cannot read superblock\n");
 418 failed:
 419         kfree(sbi);
 420         return -EINVAL;
 421
 422 Eunknown:
 423         brelse(bh);
 424         if (!silent)
 425                 printk("VFS: unable to find oldfs superblock on device %s\n",
 426                         sb->s_id);
 427         goto failed;
 428 Ebadsize:
 429         brelse(bh);
 430         if (!silent)
 431                 printk("VFS: oldfs: unsupported block size (%dKb)\n",
 432                         1<<(size-2));
 433         goto failed;
 434 }
 435
 436 static int v7_fill_super(struct super_block *sb, void *data, int silent)
 437 {
 438         struct sysv_sb_info *sbi;
 439         struct buffer_head *bh, *bh2 = NULL;
 440         struct v7_super_block *v7sb;
 441         struct sysv_inode *v7i;
 442
 443         if (440 != sizeof (struct v7_super_block))
 444                 panic("V7 FS: bad super-block size");
 445         if (64 != sizeof (struct sysv_inode))
 446                 panic("sysv fs: bad i-node size");
 447
 448         sbi = kmalloc(sizeof(struct sysv_sb_info), GFP_KERNEL);
 449         if (!sbi)
 450                 return -ENOMEM;
 451         memset(sbi, 0, sizeof(struct sysv_sb_info));
 452
 453         sbi->s_sb = sb;
 454         sbi->s_block_base = 0;
 455         sbi->s_type = FSTYPE_V7;
 456         sbi->s_bytesex = BYTESEX_PDP;
 457         sb->s_fs_info = sbi;
 458
 459         sb_set_blocksize(sb, 512);
 460
 461         if ((bh = sb_bread(sb, 1)) == NULL) {
 462                 if (!silent)
 463                         printk("VFS: unable to read V7 FS superblock on "
 464                                "device %s.\n", sb->s_id);
 465                 goto failed;
 466         }
 467
 468         /* plausibility check on superblock */
 469         v7sb = (struct v7_super_block *) bh->b_data;
 470         if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
 471             fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
 472             fs32_to_cpu(sbi, v7sb->s_time) == 0)
 473                 goto failed;
 474
 475         /* plausibility check on root inode: it is a directory,
 476            with a nonzero size that is a multiple of 16 */
 477         if ((bh2 = sb_bread(sb, 2)) == NULL)
 478                 goto failed;
 479         v7i = (struct sysv_inode *)(bh2->b_data + 64);
 480         if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
 481             (fs32_to_cpu(sbi, v7i->i_size) == 0) ||
 482             (fs32_to_cpu(sbi, v7i->i_size) & 017) != 0)
 483                 goto failed;
 484         brelse(bh2);
 485         bh2 = NULL;
 486
 487         sbi->s_bh1 = bh;
 488         sbi->s_bh2 = bh;
 489         if (complete_read_super(sb, silent, 1))
 490                 return 0;
 491
 492 failed:
 493         brelse(bh2);
 494         brelse(bh);
 495         kfree(sbi);
 496         return -EINVAL;
 497 }
 498
 499 /* Every kernel module contains stuff like this. */
 500
 501 static struct super_block *sysv_get_sb(struct file_system_type *fs_type,
 502         int flags, const char *dev_name, void *data)
 503 {
 504         return get_sb_bdev(fs_type, flags, dev_name, data, sysv_fill_super);
 505 }
 506
 507 static struct super_block *v7_get_sb(struct file_system_type *fs_type,
 508         int flags, const char *dev_name, void *data)
 509 {
 510         return get_sb_bdev(fs_type, flags, dev_name, data, v7_fill_super);
 511 }
 512
 513 static struct file_system_type sysv_fs_type = {
 514         .owner          = THIS_MODULE,
 515         .name           = "sysv",
 516         .get_sb         = sysv_get_sb,
 517         .kill_sb        = kill_block_super,
 518         .fs_flags       = FS_REQUIRES_DEV,
 519 };
 520
 521 static struct file_system_type v7_fs_type = {
 522         .owner          = THIS_MODULE,
 523         .name           = "v7",
 524         .get_sb         = v7_get_sb,
 525         .kill_sb        = kill_block_super,
 526         .fs_flags       = FS_REQUIRES_DEV,
 527 };
 528
 529 extern int sysv_init_icache(void) __init;
 530 extern void sysv_destroy_icache(void);
 531
 532 static int __init init_sysv_fs(void)
 533 {
 534         int error;
 535
 536         error = sysv_init_icache();
 537         if (error)
 538                 goto out;
 539         error = register_filesystem(&sysv_fs_type);
 540         if (error)
 541                 goto destroy_icache;
 542         error = register_filesystem(&v7_fs_type);
 543         if (error)
 544                 goto unregister;
 545         return 0;
 546
 547 unregister:
 548         unregister_filesystem(&sysv_fs_type);
 549 destroy_icache:
 550         sysv_destroy_icache();
 551 out:
 552         return error;
 553 }
 554
 555 static void __exit exit_sysv_fs(void)
 556 {
 557         unregister_filesystem(&sysv_fs_type);
 558         unregister_filesystem(&v7_fs_type);
 559         sysv_destroy_icache();
 560 }
 561
 562 module_init(init_sysv_fs)
 563 module_exit(exit_sysv_fs)
 564 MODULE_LICENSE("GPL");