e92b991e6dda0fff10cb4ba5211a6b995a2ce153
[linux-2.6.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)
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 (*(__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 *) = {
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);
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 = iget(sb,SYSV_ROOT_INO);
336         if (!root_inode || is_bad_inode(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
354 static 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         if (1024 != sizeof (struct xenix_super_block))
362                 panic("Xenix FS: bad superblock size");
363         if (512 != sizeof (struct sysv4_super_block))
364                 panic("SystemV FS: bad superblock size");
365         if (512 != sizeof (struct sysv2_super_block))
366                 panic("SystemV FS: bad superblock size");
367         if (500 != sizeof (struct coh_super_block))
368                 panic("Coherent FS: bad superblock size");
369         if (64 != sizeof (struct sysv_inode))
370                 panic("sysv fs: bad inode size");
371
372         sbi = kmalloc(sizeof(struct sysv_sb_info), GFP_KERNEL);
373         if (!sbi)
374                 return -ENOMEM;
375         memset(sbi, 0, sizeof(struct sysv_sb_info));
376
377         sbi->s_sb = sb;
378         sbi->s_block_base = 0;
379         sb->s_fs_info = sbi;
380
381         sb_set_blocksize(sb, BLOCK_SIZE);
382
383         for (i = 0; i < ARRAY_SIZE(flavours) && !size; i++) {
384                 brelse(bh);
385                 bh = sb_bread(sb, flavours[i].block);
386                 if (!bh)
387                         continue;
388                 size = flavours[i].test(SYSV_SB(sb), bh);
389         }
390
391         if (!size)
392                 goto Eunknown;
393
394         switch (size) {
395                 case 1:
396                         blocknr = bh->b_blocknr << 1;
397                         brelse(bh);
398                         sb_set_blocksize(sb, 512);
399                         bh1 = sb_bread(sb, blocknr);
400                         bh = sb_bread(sb, blocknr + 1);
401                         break;
402                 case 2:
403                         bh1 = bh;
404                         break;
405                 case 3:
406                         blocknr = bh->b_blocknr >> 1;
407                         brelse(bh);
408                         sb_set_blocksize(sb, 2048);
409                         bh1 = bh = sb_bread(sb, blocknr);
410                         break;
411                 default:
412                         goto Ebadsize;
413         }
414
415         if (bh && bh1) {
416                 sbi->s_bh1 = bh1;
417                 sbi->s_bh2 = bh;
418                 if (complete_read_super(sb, silent, size))
419                         return 0;
420         }
421
422         brelse(bh1);
423         brelse(bh);
424         sb_set_blocksize(sb, BLOCK_SIZE);
425         printk("oldfs: cannot read superblock\n");
426 failed:
427         kfree(sbi);
428         return -EINVAL;
429
430 Eunknown:
431         brelse(bh);
432         if (!silent)
433                 printk("VFS: unable to find oldfs superblock on device %s\n",
434                         sb->s_id);
435         goto failed;
436 Ebadsize:
437         brelse(bh);
438         if (!silent)
439                 printk("VFS: oldfs: unsupported block size (%dKb)\n",
440                         1<<(size-2));
441         goto failed;
442 }
443
444 static int v7_fill_super(struct super_block *sb, void *data, int silent)
445 {
446         struct sysv_sb_info *sbi;
447         struct buffer_head *bh, *bh2 = NULL;
448         struct v7_super_block *v7sb;
449         struct sysv_inode *v7i;
450
451         if (440 != sizeof (struct v7_super_block))
452                 panic("V7 FS: bad super-block size");
453         if (64 != sizeof (struct sysv_inode))
454                 panic("sysv fs: bad i-node size");
455
456         sbi = kmalloc(sizeof(struct sysv_sb_info), GFP_KERNEL);
457         if (!sbi)
458                 return -ENOMEM;
459         memset(sbi, 0, sizeof(struct sysv_sb_info));
460
461         sbi->s_sb = sb;
462         sbi->s_block_base = 0;
463         sbi->s_type = FSTYPE_V7;
464         sbi->s_bytesex = BYTESEX_PDP;
465         sb->s_fs_info = sbi;
466         
467         sb_set_blocksize(sb, 512);
468
469         if ((bh = sb_bread(sb, 1)) == NULL) {
470                 if (!silent)
471                         printk("VFS: unable to read V7 FS superblock on "
472                                "device %s.\n", sb->s_id);
473                 goto failed;
474         }
475
476         /* plausibility check on superblock */
477         v7sb = (struct v7_super_block *) bh->b_data;
478         if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
479             fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
480             fs32_to_cpu(sbi, v7sb->s_time) == 0)
481                 goto failed;
482
483         /* plausibility check on root inode: it is a directory,
484            with a nonzero size that is a multiple of 16 */
485         if ((bh2 = sb_bread(sb, 2)) == NULL)
486                 goto failed;
487         v7i = (struct sysv_inode *)(bh2->b_data + 64);
488         if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
489             (fs32_to_cpu(sbi, v7i->i_size) == 0) ||
490             (fs32_to_cpu(sbi, v7i->i_size) & 017) != 0)
491                 goto failed;
492         brelse(bh2);
493         bh2 = NULL;
494
495         sbi->s_bh1 = bh;
496         sbi->s_bh2 = bh;
497         if (complete_read_super(sb, silent, 1))
498                 return 0;
499
500 failed:
501         brelse(bh2);
502         brelse(bh);
503         kfree(sbi);
504         return -EINVAL;
505 }
506
507 /* Every kernel module contains stuff like this. */
508
509 static struct super_block *sysv_get_sb(struct file_system_type *fs_type,
510         int flags, const char *dev_name, void *data)
511 {
512         return get_sb_bdev(fs_type, flags, dev_name, data, sysv_fill_super);
513 }
514
515 static struct super_block *v7_get_sb(struct file_system_type *fs_type,
516         int flags, const char *dev_name, void *data)
517 {
518         return get_sb_bdev(fs_type, flags, dev_name, data, v7_fill_super);
519 }
520
521 static struct file_system_type sysv_fs_type = {
522         .owner          = THIS_MODULE,
523         .name           = "sysv",
524         .get_sb         = sysv_get_sb,
525         .kill_sb        = kill_block_super,
526         .fs_flags       = FS_REQUIRES_DEV,
527 };
528
529 static struct file_system_type v7_fs_type = {
530         .owner          = THIS_MODULE,
531         .name           = "v7",
532         .get_sb         = v7_get_sb,
533         .kill_sb        = kill_block_super,
534         .fs_flags       = FS_REQUIRES_DEV,
535 };
536
537 extern int sysv_init_icache(void) __init;
538 extern void sysv_destroy_icache(void);
539
540 static int __init init_sysv_fs(void)
541 {
542         int error;
543
544         error = sysv_init_icache();
545         if (error)
546                 goto out;
547         error = register_filesystem(&sysv_fs_type);
548         if (error)
549                 goto destroy_icache;
550         error = register_filesystem(&v7_fs_type);
551         if (error)
552                 goto unregister;
553         return 0;
554
555 unregister:
556         unregister_filesystem(&sysv_fs_type);
557 destroy_icache:
558         sysv_destroy_icache();
559 out:
560         return error;
561 }
562
563 static void __exit exit_sysv_fs(void)
564 {
565         unregister_filesystem(&sysv_fs_type);
566         unregister_filesystem(&v7_fs_type);
567         sysv_destroy_icache();
568 }
569
570 module_init(init_sysv_fs)
571 module_exit(exit_sysv_fs)
572 MODULE_LICENSE("GPL");