linux/fs/sysv/super.c
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   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
  43enum {
  44        JAN_1_1980 = (10*365 + 2) * 24 * 60 * 60
  45};
  46
  47static 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
  78static 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
 106static 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
 134static 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
 157static 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
 178static 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
 199static 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
 252static 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
 265static 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
 272static 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
 284static 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
 293static 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
 302static 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 = sysv_iget(sb, SYSV_ROOT_INO);
 336        if (IS_ERR(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
 354static 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");
 420failed:
 421        kfree(sbi);
 422        return -EINVAL;
 423
 424Eunknown:
 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;
 430Ebadsize:
 431        brelse(bh);
 432        if (!silent)
 433                printk("VFS: oldfs: unsupported block size (%dKb)\n",
 434                        1<<(size-2));
 435        goto failed;
 436}
 437
 438static 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
 493failed:
 494        brelse(bh2);
 495        brelse(bh);
 496        kfree(sbi);
 497        return -EINVAL;
 498}
 499
 500/* Every kernel module contains stuff like this. */
 501
 502static 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
 509static 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
 515static 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
 523static 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
 531static 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
 546unregister:
 547        unregister_filesystem(&sysv_fs_type);
 548destroy_icache:
 549        sysv_destroy_icache();
 550out:
 551        return error;
 552}
 553
 554static 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
 561module_init(init_sysv_fs)
 562module_exit(exit_sysv_fs)
 563MODULE_LICENSE("GPL");
 564