1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/fs/sysv/inode.c 4 * 5 * minix/inode.c 6 * Copyright (C) 1991, 1992 Linus Torvalds 7 * 8 * xenix/inode.c 9 * Copyright (C) 1992 Doug Evans 10 * 11 * coh/inode.c 12 * Copyright (C) 1993 Pascal Haible, Bruno Haible 13 * 14 * sysv/inode.c 15 * Copyright (C) 1993 Paul B. Monday 16 * 17 * sysv/inode.c 18 * Copyright (C) 1993 Bruno Haible 19 * Copyright (C) 1997, 1998 Krzysztof G. Baranowski 20 * 21 * This file contains code for read/parsing the superblock. 22 */ 23 24 #include <linux/module.h> 25 #include <linux/init.h> 26 #include <linux/slab.h> 27 #include <linux/buffer_head.h> 28 #include "sysv.h" 29 30 /* 31 * The following functions try to recognize specific filesystems. 32 * 33 * We recognize: 34 * - Xenix FS by its magic number. 35 * - SystemV FS by its magic number. 36 * - Coherent FS by its funny fname/fpack field. 37 * - SCO AFS by s_nfree == 0xffff 38 * - V7 FS has no distinguishing features. 39 * 40 * We discriminate among SystemV4 and SystemV2 FS by the assumption that 41 * the time stamp is not < 01-01-1980. 42 */ 43 44 enum { 45 JAN_1_1980 = (10*365 + 2) * 24 * 60 * 60 46 }; 47 48 static void detected_xenix(struct sysv_sb_info *sbi, unsigned *max_links) 49 { 50 struct buffer_head *bh1 = sbi->s_bh1; 51 struct buffer_head *bh2 = sbi->s_bh2; 52 struct xenix_super_block * sbd1; 53 struct xenix_super_block * sbd2; 54 55 if (bh1 != bh2) 56 sbd1 = sbd2 = (struct xenix_super_block *) bh1->b_data; 57 else { 58 /* block size = 512, so bh1 != bh2 */ 59 sbd1 = (struct xenix_super_block *) bh1->b_data; 60 sbd2 = (struct xenix_super_block *) (bh2->b_data - 512); 61 } 62 63 *max_links = XENIX_LINK_MAX; 64 sbi->s_fic_size = XENIX_NICINOD; 65 sbi->s_flc_size = XENIX_NICFREE; 66 sbi->s_sbd1 = (char *)sbd1; 67 sbi->s_sbd2 = (char *)sbd2; 68 sbi->s_sb_fic_count = &sbd1->s_ninode; 69 sbi->s_sb_fic_inodes = &sbd1->s_inode[0]; 70 sbi->s_sb_total_free_inodes = &sbd2->s_tinode; 71 sbi->s_bcache_count = &sbd1->s_nfree; 72 sbi->s_bcache = &sbd1->s_free[0]; 73 sbi->s_free_blocks = &sbd2->s_tfree; 74 sbi->s_sb_time = &sbd2->s_time; 75 sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd1->s_isize); 76 sbi->s_nzones = fs32_to_cpu(sbi, sbd1->s_fsize); 77 } 78 79 static void detected_sysv4(struct sysv_sb_info *sbi, unsigned *max_links) 80 { 81 struct sysv4_super_block * sbd; 82 struct buffer_head *bh1 = sbi->s_bh1; 83 struct buffer_head *bh2 = sbi->s_bh2; 84 85 if (bh1 == bh2) 86 sbd = (struct sysv4_super_block *) (bh1->b_data + BLOCK_SIZE/2); 87 else 88 sbd = (struct sysv4_super_block *) bh2->b_data; 89 90 *max_links = SYSV_LINK_MAX; 91 sbi->s_fic_size = SYSV_NICINOD; 92 sbi->s_flc_size = SYSV_NICFREE; 93 sbi->s_sbd1 = (char *)sbd; 94 sbi->s_sbd2 = (char *)sbd; 95 sbi->s_sb_fic_count = &sbd->s_ninode; 96 sbi->s_sb_fic_inodes = &sbd->s_inode[0]; 97 sbi->s_sb_total_free_inodes = &sbd->s_tinode; 98 sbi->s_bcache_count = &sbd->s_nfree; 99 sbi->s_bcache = &sbd->s_free[0]; 100 sbi->s_free_blocks = &sbd->s_tfree; 101 sbi->s_sb_time = &sbd->s_time; 102 sbi->s_sb_state = &sbd->s_state; 103 sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd->s_isize); 104 sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize); 105 } 106 107 static void detected_sysv2(struct sysv_sb_info *sbi, unsigned *max_links) 108 { 109 struct sysv2_super_block *sbd; 110 struct buffer_head *bh1 = sbi->s_bh1; 111 struct buffer_head *bh2 = sbi->s_bh2; 112 113 if (bh1 == bh2) 114 sbd = (struct sysv2_super_block *) (bh1->b_data + BLOCK_SIZE/2); 115 else 116 sbd = (struct sysv2_super_block *) bh2->b_data; 117 118 *max_links = SYSV_LINK_MAX; 119 sbi->s_fic_size = SYSV_NICINOD; 120 sbi->s_flc_size = SYSV_NICFREE; 121 sbi->s_sbd1 = (char *)sbd; 122 sbi->s_sbd2 = (char *)sbd; 123 sbi->s_sb_fic_count = &sbd->s_ninode; 124 sbi->s_sb_fic_inodes = &sbd->s_inode[0]; 125 sbi->s_sb_total_free_inodes = &sbd->s_tinode; 126 sbi->s_bcache_count = &sbd->s_nfree; 127 sbi->s_bcache = &sbd->s_free[0]; 128 sbi->s_free_blocks = &sbd->s_tfree; 129 sbi->s_sb_time = &sbd->s_time; 130 sbi->s_sb_state = &sbd->s_state; 131 sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd->s_isize); 132 sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize); 133 } 134 135 static void detected_coherent(struct sysv_sb_info *sbi, unsigned *max_links) 136 { 137 struct coh_super_block * sbd; 138 struct buffer_head *bh1 = sbi->s_bh1; 139 140 sbd = (struct coh_super_block *) bh1->b_data; 141 142 *max_links = COH_LINK_MAX; 143 sbi->s_fic_size = COH_NICINOD; 144 sbi->s_flc_size = COH_NICFREE; 145 sbi->s_sbd1 = (char *)sbd; 146 sbi->s_sbd2 = (char *)sbd; 147 sbi->s_sb_fic_count = &sbd->s_ninode; 148 sbi->s_sb_fic_inodes = &sbd->s_inode[0]; 149 sbi->s_sb_total_free_inodes = &sbd->s_tinode; 150 sbi->s_bcache_count = &sbd->s_nfree; 151 sbi->s_bcache = &sbd->s_free[0]; 152 sbi->s_free_blocks = &sbd->s_tfree; 153 sbi->s_sb_time = &sbd->s_time; 154 sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd->s_isize); 155 sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize); 156 } 157 158 static void detected_v7(struct sysv_sb_info *sbi, unsigned *max_links) 159 { 160 struct buffer_head *bh2 = sbi->s_bh2; 161 struct v7_super_block *sbd = (struct v7_super_block *)bh2->b_data; 162 163 *max_links = V7_LINK_MAX; 164 sbi->s_fic_size = V7_NICINOD; 165 sbi->s_flc_size = V7_NICFREE; 166 sbi->s_sbd1 = (char *)sbd; 167 sbi->s_sbd2 = (char *)sbd; 168 sbi->s_sb_fic_count = &sbd->s_ninode; 169 sbi->s_sb_fic_inodes = &sbd->s_inode[0]; 170 sbi->s_sb_total_free_inodes = &sbd->s_tinode; 171 sbi->s_bcache_count = &sbd->s_nfree; 172 sbi->s_bcache = &sbd->s_free[0]; 173 sbi->s_free_blocks = &sbd->s_tfree; 174 sbi->s_sb_time = &sbd->s_time; 175 sbi->s_firstdatazone = fs16_to_cpu(sbi, sbd->s_isize); 176 sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize); 177 } 178 179 static int detect_xenix(struct sysv_sb_info *sbi, struct buffer_head *bh) 180 { 181 struct xenix_super_block *sbd = (struct xenix_super_block *)bh->b_data; 182 if (*(__le32 *)&sbd->s_magic == cpu_to_le32(0x2b5544)) 183 sbi->s_bytesex = BYTESEX_LE; 184 else if (*(__be32 *)&sbd->s_magic == cpu_to_be32(0x2b5544)) 185 sbi->s_bytesex = BYTESEX_BE; 186 else 187 return 0; 188 switch (fs32_to_cpu(sbi, sbd->s_type)) { 189 case 1: 190 sbi->s_type = FSTYPE_XENIX; 191 return 1; 192 case 2: 193 sbi->s_type = FSTYPE_XENIX; 194 return 2; 195 default: 196 return 0; 197 } 198 } 199 200 static int detect_sysv(struct sysv_sb_info *sbi, struct buffer_head *bh) 201 { 202 struct super_block *sb = sbi->s_sb; 203 /* All relevant fields are at the same offsets in R2 and R4 */ 204 struct sysv4_super_block * sbd; 205 u32 type; 206 207 sbd = (struct sysv4_super_block *) (bh->b_data + BLOCK_SIZE/2); 208 if (*(__le32 *)&sbd->s_magic == cpu_to_le32(0xfd187e20)) 209 sbi->s_bytesex = BYTESEX_LE; 210 else if (*(__be32 *)&sbd->s_magic == cpu_to_be32(0xfd187e20)) 211 sbi->s_bytesex = BYTESEX_BE; 212 else 213 return 0; 214 215 type = fs32_to_cpu(sbi, sbd->s_type); 216 217 if (fs16_to_cpu(sbi, sbd->s_nfree) == 0xffff) { 218 sbi->s_type = FSTYPE_AFS; 219 sbi->s_forced_ro = 1; 220 if (!sb_rdonly(sb)) { 221 printk("SysV FS: SCO EAFS on %s detected, " 222 "forcing read-only mode.\n", 223 sb->s_id); 224 } 225 return type; 226 } 227 228 if (fs32_to_cpu(sbi, sbd->s_time) < JAN_1_1980) { 229 /* this is likely to happen on SystemV2 FS */ 230 if (type > 3 || type < 1) 231 return 0; 232 sbi->s_type = FSTYPE_SYSV2; 233 return type; 234 } 235 if ((type > 3 || type < 1) && (type > 0x30 || type < 0x10)) 236 return 0; 237 238 /* On Interactive Unix (ISC) Version 4.0/3.x s_type field = 0x10, 239 0x20 or 0x30 indicates that symbolic links and the 14-character 240 filename limit is gone. Due to lack of information about this 241 feature read-only mode seems to be a reasonable approach... -KGB */ 242 243 if (type >= 0x10) { 244 printk("SysV FS: can't handle long file names on %s, " 245 "forcing read-only mode.\n", sb->s_id); 246 sbi->s_forced_ro = 1; 247 } 248 249 sbi->s_type = FSTYPE_SYSV4; 250 return type >= 0x10 ? type >> 4 : type; 251 } 252 253 static int detect_coherent(struct sysv_sb_info *sbi, struct buffer_head *bh) 254 { 255 struct coh_super_block * sbd; 256 257 sbd = (struct coh_super_block *) (bh->b_data + BLOCK_SIZE/2); 258 if ((memcmp(sbd->s_fname,"noname",6) && memcmp(sbd->s_fname,"xxxxx ",6)) 259 || (memcmp(sbd->s_fpack,"nopack",6) && memcmp(sbd->s_fpack,"xxxxx\n",6))) 260 return 0; 261 sbi->s_bytesex = BYTESEX_PDP; 262 sbi->s_type = FSTYPE_COH; 263 return 1; 264 } 265 266 static int detect_sysv_odd(struct sysv_sb_info *sbi, struct buffer_head *bh) 267 { 268 int size = detect_sysv(sbi, bh); 269 270 return size>2 ? 0 : size; 271 } 272 273 static struct { 274 int block; 275 int (*test)(struct sysv_sb_info *, struct buffer_head *); 276 } flavours[] = { 277 {1, detect_xenix}, 278 {0, detect_sysv}, 279 {0, detect_coherent}, 280 {9, detect_sysv_odd}, 281 {15,detect_sysv_odd}, 282 {18,detect_sysv}, 283 }; 284 285 static char *flavour_names[] = { 286 [FSTYPE_XENIX] = "Xenix", 287 [FSTYPE_SYSV4] = "SystemV", 288 [FSTYPE_SYSV2] = "SystemV Release 2", 289 [FSTYPE_COH] = "Coherent", 290 [FSTYPE_V7] = "V7", 291 [FSTYPE_AFS] = "AFS", 292 }; 293 294 static void (*flavour_setup[])(struct sysv_sb_info *, unsigned *) = { 295 [FSTYPE_XENIX] = detected_xenix, 296 [FSTYPE_SYSV4] = detected_sysv4, 297 [FSTYPE_SYSV2] = detected_sysv2, 298 [FSTYPE_COH] = detected_coherent, 299 [FSTYPE_V7] = detected_v7, 300 [FSTYPE_AFS] = detected_sysv4, 301 }; 302 303 static int complete_read_super(struct super_block *sb, int silent, int size) 304 { 305 struct sysv_sb_info *sbi = SYSV_SB(sb); 306 struct inode *root_inode; 307 char *found = flavour_names[sbi->s_type]; 308 u_char n_bits = size+8; 309 int bsize = 1 << n_bits; 310 int bsize_4 = bsize >> 2; 311 312 sbi->s_firstinodezone = 2; 313 314 flavour_setup[sbi->s_type](sbi, &sb->s_max_links); 315 if (sbi->s_firstdatazone < sbi->s_firstinodezone) 316 return 0; 317 318 sbi->s_ndatazones = sbi->s_nzones - sbi->s_firstdatazone; 319 sbi->s_inodes_per_block = bsize >> 6; 320 sbi->s_inodes_per_block_1 = (bsize >> 6)-1; 321 sbi->s_inodes_per_block_bits = n_bits-6; 322 sbi->s_ind_per_block = bsize_4; 323 sbi->s_ind_per_block_2 = bsize_4*bsize_4; 324 sbi->s_toobig_block = 10 + bsize_4 * (1 + bsize_4 * (1 + bsize_4)); 325 sbi->s_ind_per_block_bits = n_bits-2; 326 327 sbi->s_ninodes = (sbi->s_firstdatazone - sbi->s_firstinodezone) 328 << sbi->s_inodes_per_block_bits; 329 330 if (!silent) 331 printk("VFS: Found a %s FS (block size = %ld) on device %s\n", 332 found, sb->s_blocksize, sb->s_id); 333 334 sb->s_magic = SYSV_MAGIC_BASE + sbi->s_type; 335 /* set up enough so that it can read an inode */ 336 sb->s_op = &sysv_sops; 337 if (sbi->s_forced_ro) 338 sb->s_flags |= SB_RDONLY; 339 root_inode = sysv_iget(sb, SYSV_ROOT_INO); 340 if (IS_ERR(root_inode)) { 341 printk("SysV FS: get root inode failed\n"); 342 return 0; 343 } 344 sb->s_root = d_make_root(root_inode); 345 if (!sb->s_root) { 346 printk("SysV FS: get root dentry failed\n"); 347 return 0; 348 } 349 return 1; 350 } 351 352 static int sysv_fill_super(struct super_block *sb, void *data, int silent) 353 { 354 struct buffer_head *bh1, *bh = NULL; 355 struct sysv_sb_info *sbi; 356 unsigned long blocknr; 357 int size = 0, i; 358 359 BUILD_BUG_ON(1024 != sizeof (struct xenix_super_block)); 360 BUILD_BUG_ON(512 != sizeof (struct sysv4_super_block)); 361 BUILD_BUG_ON(512 != sizeof (struct sysv2_super_block)); 362 BUILD_BUG_ON(500 != sizeof (struct coh_super_block)); 363 BUILD_BUG_ON(64 != sizeof (struct sysv_inode)); 364 365 sbi = kzalloc(sizeof(struct sysv_sb_info), GFP_KERNEL); 366 if (!sbi) 367 return -ENOMEM; 368 369 sbi->s_sb = sb; 370 sbi->s_block_base = 0; 371 mutex_init(&sbi->s_lock); 372 sb->s_fs_info = sbi; 373 sb->s_time_min = 0; 374 sb->s_time_max = U32_MAX; 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_sanity_check(struct super_block *sb, struct buffer_head *bh) 439 { 440 struct v7_super_block *v7sb; 441 struct sysv_inode *v7i; 442 struct buffer_head *bh2; 443 struct sysv_sb_info *sbi; 444 445 sbi = sb->s_fs_info; 446 447 /* plausibility check on superblock */ 448 v7sb = (struct v7_super_block *) bh->b_data; 449 if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE || 450 fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD || 451 fs32_to_cpu(sbi, v7sb->s_fsize) > V7_MAXSIZE) 452 return 0; 453 454 /* plausibility check on root inode: it is a directory, 455 with a nonzero size that is a multiple of 16 */ 456 bh2 = sb_bread(sb, 2); 457 if (bh2 == NULL) 458 return 0; 459 460 v7i = (struct sysv_inode *)(bh2->b_data + 64); 461 if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR || 462 (fs32_to_cpu(sbi, v7i->i_size) == 0) || 463 (fs32_to_cpu(sbi, v7i->i_size) & 017) || 464 (fs32_to_cpu(sbi, v7i->i_size) > V7_NFILES * 465 sizeof(struct sysv_dir_entry))) { 466 brelse(bh2); 467 return 0; 468 } 469 470 brelse(bh2); 471 return 1; 472 } 473 474 static int v7_fill_super(struct super_block *sb, void *data, int silent) 475 { 476 struct sysv_sb_info *sbi; 477 struct buffer_head *bh; 478 479 BUILD_BUG_ON(sizeof(struct v7_super_block) != 440); 480 BUILD_BUG_ON(sizeof(struct sysv_inode) != 64); 481 482 sbi = kzalloc(sizeof(struct sysv_sb_info), GFP_KERNEL); 483 if (!sbi) 484 return -ENOMEM; 485 486 sbi->s_sb = sb; 487 sbi->s_block_base = 0; 488 sbi->s_type = FSTYPE_V7; 489 mutex_init(&sbi->s_lock); 490 sb->s_fs_info = sbi; 491 sb->s_time_min = 0; 492 sb->s_time_max = U32_MAX; 493 494 sb_set_blocksize(sb, 512); 495 496 if ((bh = sb_bread(sb, 1)) == NULL) { 497 if (!silent) 498 printk("VFS: unable to read V7 FS superblock on " 499 "device %s.\n", sb->s_id); 500 goto failed; 501 } 502 503 /* Try PDP-11 UNIX */ 504 sbi->s_bytesex = BYTESEX_PDP; 505 if (v7_sanity_check(sb, bh)) 506 goto detected; 507 508 /* Try PC/IX, v7/x86 */ 509 sbi->s_bytesex = BYTESEX_LE; 510 if (v7_sanity_check(sb, bh)) 511 goto detected; 512 513 goto failed; 514 515 detected: 516 sbi->s_bh1 = bh; 517 sbi->s_bh2 = bh; 518 if (complete_read_super(sb, silent, 1)) 519 return 0; 520 521 failed: 522 printk(KERN_ERR "VFS: could not find a valid V7 on %s.\n", 523 sb->s_id); 524 brelse(bh); 525 kfree(sbi); 526 return -EINVAL; 527 } 528 529 /* Every kernel module contains stuff like this. */ 530 531 static struct dentry *sysv_mount(struct file_system_type *fs_type, 532 int flags, const char *dev_name, void *data) 533 { 534 return mount_bdev(fs_type, flags, dev_name, data, sysv_fill_super); 535 } 536 537 static struct dentry *v7_mount(struct file_system_type *fs_type, 538 int flags, const char *dev_name, void *data) 539 { 540 return mount_bdev(fs_type, flags, dev_name, data, v7_fill_super); 541 } 542 543 static struct file_system_type sysv_fs_type = { 544 .owner = THIS_MODULE, 545 .name = "sysv", 546 .mount = sysv_mount, 547 .kill_sb = kill_block_super, 548 .fs_flags = FS_REQUIRES_DEV, 549 }; 550 MODULE_ALIAS_FS("sysv"); 551 552 static struct file_system_type v7_fs_type = { 553 .owner = THIS_MODULE, 554 .name = "v7", 555 .mount = v7_mount, 556 .kill_sb = kill_block_super, 557 .fs_flags = FS_REQUIRES_DEV, 558 }; 559 MODULE_ALIAS_FS("v7"); 560 MODULE_ALIAS("v7"); 561 562 static int __init init_sysv_fs(void) 563 { 564 int error; 565 566 error = sysv_init_icache(); 567 if (error) 568 goto out; 569 error = register_filesystem(&sysv_fs_type); 570 if (error) 571 goto destroy_icache; 572 error = register_filesystem(&v7_fs_type); 573 if (error) 574 goto unregister; 575 return 0; 576 577 unregister: 578 unregister_filesystem(&sysv_fs_type); 579 destroy_icache: 580 sysv_destroy_icache(); 581 out: 582 return error; 583 } 584 585 static void __exit exit_sysv_fs(void) 586 { 587 unregister_filesystem(&sysv_fs_type); 588 unregister_filesystem(&v7_fs_type); 589 sysv_destroy_icache(); 590 } 591 592 module_init(init_sysv_fs) 593 module_exit(exit_sysv_fs) 594 MODULE_LICENSE("GPL"); 595