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_DESCRIPTION("SystemV Filesystem");
595 MODULE_LICENSE("GPL");
596
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.