switch open-coded instances of d_make_root() to new helper
[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, 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         sb->s_fs_info = sbi;
372
373         sb_set_blocksize(sb, BLOCK_SIZE);
374
375         for (i = 0; i < ARRAY_SIZE(flavours) && !size; i++) {
376                 brelse(bh);
377                 bh = sb_bread(sb, flavours[i].block);
378                 if (!bh)
379                         continue;
380                 size = flavours[i].test(SYSV_SB(sb), bh);
381         }
382
383         if (!size)
384                 goto Eunknown;
385
386         switch (size) {
387                 case 1:
388                         blocknr = bh->b_blocknr << 1;
389                         brelse(bh);
390                         sb_set_blocksize(sb, 512);
391                         bh1 = sb_bread(sb, blocknr);
392                         bh = sb_bread(sb, blocknr + 1);
393                         break;
394                 case 2:
395                         bh1 = bh;
396                         break;
397                 case 3:
398                         blocknr = bh->b_blocknr >> 1;
399                         brelse(bh);
400                         sb_set_blocksize(sb, 2048);
401                         bh1 = bh = sb_bread(sb, blocknr);
402                         break;
403                 default:
404                         goto Ebadsize;
405         }
406
407         if (bh && bh1) {
408                 sbi->s_bh1 = bh1;
409                 sbi->s_bh2 = bh;
410                 if (complete_read_super(sb, silent, size))
411                         return 0;
412         }
413
414         brelse(bh1);
415         brelse(bh);
416         sb_set_blocksize(sb, BLOCK_SIZE);
417         printk("oldfs: cannot read superblock\n");
418 failed:
419         kfree(sbi);
420         return -EINVAL;
421
422 Eunknown:
423         brelse(bh);
424         if (!silent)
425                 printk("VFS: unable to find oldfs superblock on device %s\n",
426                         sb->s_id);
427         goto failed;
428 Ebadsize:
429         brelse(bh);
430         if (!silent)
431                 printk("VFS: oldfs: unsupported block size (%dKb)\n",
432                         1<<(size-2));
433         goto failed;
434 }
435
436 static int v7_sanity_check(struct super_block *sb, struct buffer_head *bh)
437 {
438         struct v7_super_block *v7sb;
439         struct sysv_inode *v7i;
440         struct buffer_head *bh2;
441         struct sysv_sb_info *sbi;
442
443         sbi = sb->s_fs_info;
444
445         /* plausibility check on superblock */
446         v7sb = (struct v7_super_block *) bh->b_data;
447         if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
448             fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
449             fs32_to_cpu(sbi, v7sb->s_fsize) > V7_MAXSIZE)
450                 return 0;
451
452         /* plausibility check on root inode: it is a directory,
453            with a nonzero size that is a multiple of 16 */
454         bh2 = sb_bread(sb, 2);
455         if (bh2 == NULL)
456                 return 0;
457
458         v7i = (struct sysv_inode *)(bh2->b_data + 64);
459         if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
460             (fs32_to_cpu(sbi, v7i->i_size) == 0) ||
461             (fs32_to_cpu(sbi, v7i->i_size) & 017) ||
462             (fs32_to_cpu(sbi, v7i->i_size) > V7_NFILES *
463              sizeof(struct sysv_dir_entry))) {
464                 brelse(bh2);
465                 return 0;
466         }
467
468         brelse(bh2);
469         return 1;
470 }
471
472 static int v7_fill_super(struct super_block *sb, void *data, int silent)
473 {
474         struct sysv_sb_info *sbi;
475         struct buffer_head *bh;
476
477         if (440 != sizeof (struct v7_super_block))
478                 panic("V7 FS: bad super-block size");
479         if (64 != sizeof (struct sysv_inode))
480                 panic("sysv fs: bad i-node size");
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         sb->s_fs_info = sbi;
490         
491         sb_set_blocksize(sb, 512);
492
493         if ((bh = sb_bread(sb, 1)) == NULL) {
494                 if (!silent)
495                         printk("VFS: unable to read V7 FS superblock on "
496                                "device %s.\n", sb->s_id);
497                 goto failed;
498         }
499
500         /* Try PDP-11 UNIX */
501         sbi->s_bytesex = BYTESEX_PDP;
502         if (v7_sanity_check(sb, bh))
503                 goto detected;
504
505         /* Try PC/IX, v7/x86 */
506         sbi->s_bytesex = BYTESEX_LE;
507         if (v7_sanity_check(sb, bh))
508                 goto detected;
509
510         goto failed;
511
512 detected:
513         sbi->s_bh1 = bh;
514         sbi->s_bh2 = bh;
515         if (complete_read_super(sb, silent, 1))
516                 return 0;
517
518 failed:
519         printk(KERN_ERR "VFS: could not find a valid V7 on %s.\n",
520                 sb->s_id);
521         brelse(bh);
522         kfree(sbi);
523         return -EINVAL;
524 }
525
526 /* Every kernel module contains stuff like this. */
527
528 static struct dentry *sysv_mount(struct file_system_type *fs_type,
529         int flags, const char *dev_name, void *data)
530 {
531         return mount_bdev(fs_type, flags, dev_name, data, sysv_fill_super);
532 }
533
534 static struct dentry *v7_mount(struct file_system_type *fs_type,
535         int flags, const char *dev_name, void *data)
536 {
537         return mount_bdev(fs_type, flags, dev_name, data, v7_fill_super);
538 }
539
540 static struct file_system_type sysv_fs_type = {
541         .owner          = THIS_MODULE,
542         .name           = "sysv",
543         .mount          = sysv_mount,
544         .kill_sb        = kill_block_super,
545         .fs_flags       = FS_REQUIRES_DEV,
546 };
547
548 static struct file_system_type v7_fs_type = {
549         .owner          = THIS_MODULE,
550         .name           = "v7",
551         .mount          = v7_mount,
552         .kill_sb        = kill_block_super,
553         .fs_flags       = FS_REQUIRES_DEV,
554 };
555
556 static int __init init_sysv_fs(void)
557 {
558         int error;
559
560         error = sysv_init_icache();
561         if (error)
562                 goto out;
563         error = register_filesystem(&sysv_fs_type);
564         if (error)
565                 goto destroy_icache;
566         error = register_filesystem(&v7_fs_type);
567         if (error)
568                 goto unregister;
569         return 0;
570
571 unregister:
572         unregister_filesystem(&sysv_fs_type);
573 destroy_icache:
574         sysv_destroy_icache();
575 out:
576         return error;
577 }
578
579 static void __exit exit_sysv_fs(void)
580 {
581         unregister_filesystem(&sysv_fs_type);
582         unregister_filesystem(&v7_fs_type);
583         sysv_destroy_icache();
584 }
585
586 module_init(init_sysv_fs)
587 module_exit(exit_sysv_fs)
588 MODULE_ALIAS("v7");
589 MODULE_LICENSE("GPL");