d0c6a007ce835cf869fac695eb5445b34be6d814
[linux-3.10.git] / 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, unsigned *max_links)
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         *max_links = 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, unsigned *max_links)
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         *max_links = 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, unsigned *max_links)
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         *max_links = 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, unsigned *max_links)
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         *max_links = 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, unsigned *max_links)
158 {
159         struct buffer_head *bh2 = sbi->s_bh2;
160         struct v7_super_block *sbd = (struct v7_super_block *)bh2->b_data;
161
162         *max_links = 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 *, unsigned *) = {
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, &sb->s_max_links);
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         if (sbi->s_forced_ro)
336                 sb->s_flags |= MS_RDONLY;
337         if (sbi->s_truncate)
338                 sb->s_d_op = &sysv_dentry_operations;
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
374         sb_set_blocksize(sb, BLOCK_SIZE);
375
376         for (i = 0; i < ARRAY_SIZE(flavours) && !size; i++) {
377                 brelse(bh);
378                 bh = sb_bread(sb, flavours[i].block);
379                 if (!bh)
380                         continue;
381                 size = flavours[i].test(SYSV_SB(sb), bh);
382         }
383
384         if (!size)
385                 goto Eunknown;
386
387         switch (size) {
388                 case 1:
389                         blocknr = bh->b_blocknr << 1;
390                         brelse(bh);
391                         sb_set_blocksize(sb, 512);
392                         bh1 = sb_bread(sb, blocknr);
393                         bh = sb_bread(sb, blocknr + 1);
394                         break;
395                 case 2:
396                         bh1 = bh;
397                         break;
398                 case 3:
399                         blocknr = bh->b_blocknr >> 1;
400                         brelse(bh);
401                         sb_set_blocksize(sb, 2048);
402                         bh1 = bh = sb_bread(sb, blocknr);
403                         break;
404                 default:
405                         goto Ebadsize;
406         }
407
408         if (bh && bh1) {
409                 sbi->s_bh1 = bh1;
410                 sbi->s_bh2 = bh;
411                 if (complete_read_super(sb, silent, size))
412                         return 0;
413         }
414
415         brelse(bh1);
416         brelse(bh);
417         sb_set_blocksize(sb, BLOCK_SIZE);
418         printk("oldfs: cannot read superblock\n");
419 failed:
420         kfree(sbi);
421         return -EINVAL;
422
423 Eunknown:
424         brelse(bh);
425         if (!silent)
426                 printk("VFS: unable to find oldfs superblock on device %s\n",
427                         sb->s_id);
428         goto failed;
429 Ebadsize:
430         brelse(bh);
431         if (!silent)
432                 printk("VFS: oldfs: unsupported block size (%dKb)\n",
433                         1<<(size-2));
434         goto failed;
435 }
436
437 static int v7_sanity_check(struct super_block *sb, struct buffer_head *bh)
438 {
439         struct v7_super_block *v7sb;
440         struct sysv_inode *v7i;
441         struct buffer_head *bh2;
442         struct sysv_sb_info *sbi;
443
444         sbi = sb->s_fs_info;
445
446         /* plausibility check on superblock */
447         v7sb = (struct v7_super_block *) bh->b_data;
448         if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
449             fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
450             fs32_to_cpu(sbi, v7sb->s_fsize) > V7_MAXSIZE)
451                 return 0;
452
453         /* plausibility check on root inode: it is a directory,
454            with a nonzero size that is a multiple of 16 */
455         bh2 = sb_bread(sb, 2);
456         if (bh2 == NULL)
457                 return 0;
458
459         v7i = (struct sysv_inode *)(bh2->b_data + 64);
460         if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
461             (fs32_to_cpu(sbi, v7i->i_size) == 0) ||
462             (fs32_to_cpu(sbi, v7i->i_size) & 017) ||
463             (fs32_to_cpu(sbi, v7i->i_size) > V7_NFILES *
464              sizeof(struct sysv_dir_entry))) {
465                 brelse(bh2);
466                 return 0;
467         }
468
469         brelse(bh2);
470         return 1;
471 }
472
473 static int v7_fill_super(struct super_block *sb, void *data, int silent)
474 {
475         struct sysv_sb_info *sbi;
476         struct buffer_head *bh;
477
478         if (440 != sizeof (struct v7_super_block))
479                 panic("V7 FS: bad super-block size");
480         if (64 != sizeof (struct sysv_inode))
481                 panic("sysv fs: bad i-node size");
482
483         sbi = kzalloc(sizeof(struct sysv_sb_info), GFP_KERNEL);
484         if (!sbi)
485                 return -ENOMEM;
486
487         sbi->s_sb = sb;
488         sbi->s_block_base = 0;
489         sbi->s_type = FSTYPE_V7;
490         sb->s_fs_info = sbi;
491         
492         sb_set_blocksize(sb, 512);
493
494         if ((bh = sb_bread(sb, 1)) == NULL) {
495                 if (!silent)
496                         printk("VFS: unable to read V7 FS superblock on "
497                                "device %s.\n", sb->s_id);
498                 goto failed;
499         }
500
501         /* Try PDP-11 UNIX */
502         sbi->s_bytesex = BYTESEX_PDP;
503         if (v7_sanity_check(sb, bh))
504                 goto detected;
505
506         /* Try PC/IX, v7/x86 */
507         sbi->s_bytesex = BYTESEX_LE;
508         if (v7_sanity_check(sb, bh))
509                 goto detected;
510
511         goto failed;
512
513 detected:
514         sbi->s_bh1 = bh;
515         sbi->s_bh2 = bh;
516         if (complete_read_super(sb, silent, 1))
517                 return 0;
518
519 failed:
520         printk(KERN_ERR "VFS: could not find a valid V7 on %s.\n",
521                 sb->s_id);
522         brelse(bh);
523         kfree(sbi);
524         return -EINVAL;
525 }
526
527 /* Every kernel module contains stuff like this. */
528
529 static struct dentry *sysv_mount(struct file_system_type *fs_type,
530         int flags, const char *dev_name, void *data)
531 {
532         return mount_bdev(fs_type, flags, dev_name, data, sysv_fill_super);
533 }
534
535 static struct dentry *v7_mount(struct file_system_type *fs_type,
536         int flags, const char *dev_name, void *data)
537 {
538         return mount_bdev(fs_type, flags, dev_name, data, v7_fill_super);
539 }
540
541 static struct file_system_type sysv_fs_type = {
542         .owner          = THIS_MODULE,
543         .name           = "sysv",
544         .mount          = sysv_mount,
545         .kill_sb        = kill_block_super,
546         .fs_flags       = FS_REQUIRES_DEV,
547 };
548 MODULE_ALIAS_FS("sysv");
549
550 static struct file_system_type v7_fs_type = {
551         .owner          = THIS_MODULE,
552         .name           = "v7",
553         .mount          = v7_mount,
554         .kill_sb        = kill_block_super,
555         .fs_flags       = FS_REQUIRES_DEV,
556 };
557 MODULE_ALIAS_FS("v7");
558 MODULE_ALIAS("v7");
559
560 static int __init init_sysv_fs(void)
561 {
562         int error;
563
564         error = sysv_init_icache();
565         if (error)
566                 goto out;
567         error = register_filesystem(&sysv_fs_type);
568         if (error)
569                 goto destroy_icache;
570         error = register_filesystem(&v7_fs_type);
571         if (error)
572                 goto unregister;
573         return 0;
574
575 unregister:
576         unregister_filesystem(&sysv_fs_type);
577 destroy_icache:
578         sysv_destroy_icache();
579 out:
580         return error;
581 }
582
583 static void __exit exit_sysv_fs(void)
584 {
585         unregister_filesystem(&sysv_fs_type);
586         unregister_filesystem(&v7_fs_type);
587         sysv_destroy_icache();
588 }
589
590 module_init(init_sysv_fs)
591 module_exit(exit_sysv_fs)
592 MODULE_LICENSE("GPL");