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MOXA linux-2.6.x / linux-2.6.9-uc0 from sdlinux-moxaart.tgz
[linux-2.6.9-moxart.git] / fs / romfs / inode.c
blob8f99bd4c8531cad4c87ececd922e1e205f58b2d3
1 /*
2 * ROMFS file system, Linux implementation
3 *
4 * Copyright (C) 1997-1999 Janos Farkas <chexum@shadow.banki.hu>
5 *
6 * Using parts of the minix filesystem
7 * Copyright (C) 1991, 1992 Linus Torvalds
8 *
9 * and parts of the affs filesystem additionally
10 * Copyright (C) 1993 Ray Burr
11 * Copyright (C) 1996 Hans-Joachim Widmaier
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 *
18 * Changes
19 * Changed for 2.1.19 modules
20 * Jan 1997 Initial release
21 * Jun 1997 2.1.43+ changes
22 * Proper page locking in readpage
23 * Changed to work with 2.1.45+ fs
24 * Jul 1997 Fixed follow_link
25 * 2.1.47
26 * lookup shouldn't return -ENOENT
27 * from Horst von Brand:
28 * fail on wrong checksum
29 * double unlock_super was possible
30 * correct namelen for statfs
31 * spotted by Bill Hawes:
32 * readlink shouldn't iput()
33 * Jun 1998 2.1.106 from Avery Pennarun: glibc scandir()
34 * exposed a problem in readdir
35 * 2.1.107 code-freeze spellchecker run
36 * Aug 1998 2.1.118+ VFS changes
37 * Sep 1998 2.1.122 another VFS change (follow_link)
38 * Apr 1999 2.2.7 no more EBADF checking in
39 * lookup/readdir, use ERR_PTR
40 * Jun 1999 2.3.6 d_alloc_root use changed
41 * 2.3.9 clean up usage of ENOENT/negative
42 * dentries in lookup
43 * clean up page flags setting
44 * (error, uptodate, locking) in
45 * in readpage
46 * use init_special_inode for
47 * fifos/sockets (and streamline) in
48 * read_inode, fix _ops table order
49 * Aug 1999 2.3.16 __initfunc() => __init change
50 * Oct 1999 2.3.24 page->owner hack obsoleted
51 * Nov 1999 2.3.27 2.3.25+ page->offset => index change
52 */
53
54 /* todo:
55 * - see Documentation/filesystems/romfs.txt
56 * - use allocated, not stack memory for file names?
57 * - considering write access...
58 * - network (tftp) files?
59 * - merge back some _op tables
60 */
61
62 /*
63 * Sorry about some optimizations and for some goto's. I just wanted
64 * to squeeze some more bytes out of this code.. :)
65 */
66
67 #include <linux/module.h>
68 #include <linux/types.h>
69 #include <linux/errno.h>
70 #include <linux/slab.h>
71 #include <linux/romfs_fs.h>
72 #include <linux/fs.h>
73 #include <linux/init.h>
74 #include <linux/pagemap.h>
75 #include <linux/smp_lock.h>
76 #include <linux/buffer_head.h>
77 #include <linux/vfs.h>
78
79 #include <asm/uaccess.h>
80
81 struct romfs_inode_info {
82 unsigned long i_metasize; /* size of non-data area */
83 unsigned long i_dataoffset; /* from the start of fs */
84 struct inode vfs_inode;
85 };
86
87 /* instead of private superblock data */
88 static inline unsigned long romfs_maxsize(struct super_block *sb)
89 {
90 return (unsigned long)sb->s_fs_info;
91 }
92
93 static inline struct romfs_inode_info *ROMFS_I(struct inode *inode)
94 {
95 return list_entry(inode, struct romfs_inode_info, vfs_inode);
96 }
97
98 static __u32
99 romfs_checksum(void *data, int size)
100 {
101 __u32 sum;
102 __be32 *ptr;
103
104 sum = 0; ptr = data;
105 size>>=2;
106 while (size>0) {
107 sum += be32_to_cpu(*ptr++);
108 size--;
109 }
110 return sum;
111 }
112
113 static struct super_operations romfs_ops;
114
115 static int romfs_fill_super(struct super_block *s, void *data, int silent)
116 {
117 struct buffer_head *bh;
118 struct romfs_super_block *rsb;
119 struct inode *root;
120 int sz;
121
122 /* I would parse the options here, but there are none.. :) */
123
124 sb_set_blocksize(s, ROMBSIZE);
125 s->s_maxbytes = 0xFFFFFFFF;
126
127 bh = sb_bread(s, 0);
128 if (!bh) {
129 /* XXX merge with other printk? */
130 printk ("romfs: unable to read superblock\n");
131 goto outnobh;
132 }
133
134 rsb = (struct romfs_super_block *)bh->b_data;
135 sz = be32_to_cpu(rsb->size);
136 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1
137 || sz < ROMFH_SIZE) {
138 if (!silent)
139 printk ("VFS: Can't find a romfs filesystem on dev "
140 "%s.\n", s->s_id);
141 goto out;
142 }
143 if (romfs_checksum(rsb, min_t(int, sz, 512))) {
144 printk ("romfs: bad initial checksum on dev "
145 "%s.\n", s->s_id);
146 goto out;
147 }
148
149 s->s_magic = ROMFS_MAGIC;
150 s->s_fs_info = (void *)(long)sz;
151
152 s->s_flags |= MS_RDONLY;
153
154 /* Find the start of the fs */
155 sz = (ROMFH_SIZE +
156 strnlen(rsb->name, ROMFS_MAXFN) + 1 + ROMFH_PAD)
157 & ROMFH_MASK;
158
159 s->s_op = &romfs_ops;
160 root = iget(s, sz);
161 if (!root)
162 goto out;
163
164 s->s_root = d_alloc_root(iget(s, sz));
165
166 if (!s->s_root)
167 goto outiput;
168
169 brelse(bh);
170 return 0;
171
172 outiput:
173 iput(root);
174 out:
175 brelse(bh);
176 outnobh:
177 return -EINVAL;
178 }
179
180 /* That's simple too. */
181
182 static int
183 romfs_statfs(struct super_block *sb, struct kstatfs *buf)
184 {
185 buf->f_type = ROMFS_MAGIC;
186 buf->f_bsize = ROMBSIZE;
187 buf->f_bfree = buf->f_bavail = buf->f_ffree;
188 buf->f_blocks = (romfs_maxsize(sb)+ROMBSIZE-1)>>ROMBSBITS;
189 buf->f_namelen = ROMFS_MAXFN;
190 return 0;
191 }
192
193 /* some helper routines */
194
195 static int
196 romfs_strnlen(struct inode *i, unsigned long offset, unsigned long count)
197 {
198 struct buffer_head *bh;
199 unsigned long avail, maxsize, res;
200
201 maxsize = romfs_maxsize(i->i_sb);
202 if (offset >= maxsize)
203 return -1;
204
205 /* strnlen is almost always valid */
206 if (count > maxsize || offset+count > maxsize)
207 count = maxsize-offset;
208
209 bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
210 if (!bh)
211 return -1; /* error */
212
213 avail = ROMBSIZE - (offset & ROMBMASK);
214 maxsize = min_t(unsigned long, count, avail);
215 res = strnlen(((char *)bh->b_data)+(offset&ROMBMASK), maxsize);
216 brelse(bh);
217
218 if (res < maxsize)
219 return res; /* found all of it */
220
221 while (res < count) {
222 offset += maxsize;
223
224 bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
225 if (!bh)
226 return -1;
227 maxsize = min_t(unsigned long, count - res, ROMBSIZE);
228 avail = strnlen(bh->b_data, maxsize);
229 res += avail;
230 brelse(bh);
231 if (avail < maxsize)
232 return res;
233 }
234 return res;
235 }
236
237 static int
238 romfs_copyfrom(struct inode *i, void *dest, unsigned long offset, unsigned long count)
239 {
240 struct buffer_head *bh;
241 unsigned long avail, maxsize, res;
242
243 maxsize = romfs_maxsize(i->i_sb);
244 if (offset >= maxsize || count > maxsize || offset+count>maxsize)
245 return -1;
246
247 bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
248 if (!bh)
249 return -1; /* error */
250
251 avail = ROMBSIZE - (offset & ROMBMASK);
252 maxsize = min_t(unsigned long, count, avail);
253 memcpy(dest, ((char *)bh->b_data) + (offset & ROMBMASK), maxsize);
254 brelse(bh);
255
256 res = maxsize; /* all of it */
257
258 while (res < count) {
259 offset += maxsize;
260 dest += maxsize;
261
262 bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
263 if (!bh)
264 return -1;
265 maxsize = min_t(unsigned long, count - res, ROMBSIZE);
266 memcpy(dest, bh->b_data, maxsize);
267 brelse(bh);
268 res += maxsize;
269 }
270 return res;
271 }
272
273 static unsigned char romfs_dtype_table[] = {
274 DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
275 };
276
277 static int
278 romfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
279 {
280 struct inode *i = filp->f_dentry->d_inode;
281 struct romfs_inode ri;
282 unsigned long offset, maxoff;
283 int j, ino, nextfh;
284 int stored = 0;
285 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
286
287 lock_kernel();
288
289 maxoff = romfs_maxsize(i->i_sb);
290
291 offset = filp->f_pos;
292 if (!offset) {
293 offset = i->i_ino & ROMFH_MASK;
294 if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 0)
295 goto out;
296 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
297 }
298
299 /* Not really failsafe, but we are read-only... */
300 for(;;) {
301 if (!offset || offset >= maxoff) {
302 offset = maxoff;
303 filp->f_pos = offset;
304 goto out;
305 }
306 filp->f_pos = offset;
307
308 /* Fetch inode info */
309 if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 0)
310 goto out;
311
312 j = romfs_strnlen(i, offset+ROMFH_SIZE, sizeof(fsname)-1);
313 if (j < 0)
314 goto out;
315
316 fsname[j]=0;
317 romfs_copyfrom(i, fsname, offset+ROMFH_SIZE, j);
318
319 ino = offset;
320 nextfh = be32_to_cpu(ri.next);
321 if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
322 ino = be32_to_cpu(ri.spec);
323 if (filldir(dirent, fsname, j, offset, ino,
324 romfs_dtype_table[nextfh & ROMFH_TYPE]) < 0) {
325 goto out;
326 }
327 stored++;
328 offset = nextfh & ROMFH_MASK;
329 }
330 out:
331 unlock_kernel();
332 return stored;
333 }
334
335 static struct dentry *
336 romfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
337 {
338 unsigned long offset, maxoff;
339 int fslen, res;
340 struct inode *inode;
341 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
342 struct romfs_inode ri;
343 const char *name; /* got from dentry */
344 int len;
345
346 res = -EACCES; /* placeholder for "no data here" */
347 offset = dir->i_ino & ROMFH_MASK;
348 lock_kernel();
349 if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
350 goto out;
351
352 maxoff = romfs_maxsize(dir->i_sb);
353 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
354
355 /* OK, now find the file whose name is in "dentry" in the
356 * directory specified by "dir". */
357
358 name = dentry->d_name.name;
359 len = dentry->d_name.len;
360
361 for(;;) {
362 if (!offset || offset >= maxoff)
363 goto out0;
364 if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
365 goto out;
366
367 /* try to match the first 16 bytes of name */
368 fslen = romfs_strnlen(dir, offset+ROMFH_SIZE, ROMFH_SIZE);
369 if (len < ROMFH_SIZE) {
370 if (len == fslen) {
371 /* both are shorter, and same size */
372 romfs_copyfrom(dir, fsname, offset+ROMFH_SIZE, len+1);
373 if (strncmp (name, fsname, len) == 0)
374 break;
375 }
376 } else if (fslen >= ROMFH_SIZE) {
377 /* both are longer; XXX optimize max size */
378 fslen = romfs_strnlen(dir, offset+ROMFH_SIZE, sizeof(fsname)-1);
379 if (len == fslen) {
380 romfs_copyfrom(dir, fsname, offset+ROMFH_SIZE, len+1);
381 if (strncmp(name, fsname, len) == 0)
382 break;
383 }
384 }
385 /* next entry */
386 offset = be32_to_cpu(ri.next) & ROMFH_MASK;
387 }
388
389 /* Hard link handling */
390 if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
391 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
392
393 if ((inode = iget(dir->i_sb, offset)))
394 goto outi;
395
396 /*
397 * it's a bit funky, _lookup needs to return an error code
398 * (negative) or a NULL, both as a dentry. ENOENT should not
399 * be returned, instead we need to create a negative dentry by
400 * d_add(dentry, NULL); and return 0 as no error.
401 * (Although as I see, it only matters on writable file
402 * systems).
403 */
404
405 out0: inode = NULL;
406 outi: res = 0;
407 d_add (dentry, inode);
408
409 out: unlock_kernel();
410 return ERR_PTR(res);
411 }
412
413 /*
414 * Ok, we do readpage, to be able to execute programs. Unfortunately,
415 * we can't use bmap, since we may have looser alignments.
416 */
417
418 static int
419 romfs_readpage(struct file *file, struct page * page)
420 {
421 struct inode *inode = page->mapping->host;
422 unsigned long offset, avail, readlen;
423 void *buf;
424 int result = -EIO;
425
426 page_cache_get(page);
427 lock_kernel();
428 buf = kmap(page);
429 if (!buf)
430 goto err_out;
431
432 /* 32 bit warning -- but not for us :) */
433 offset = page->index << PAGE_CACHE_SHIFT;
434 if (offset < inode->i_size) {
435 avail = inode->i_size-offset;
436 readlen = min_t(unsigned long, avail, PAGE_SIZE);
437 if (romfs_copyfrom(inode, buf, ROMFS_I(inode)->i_dataoffset+offset, readlen) == readlen) {
438 if (readlen < PAGE_SIZE) {
439 memset(buf + readlen,0,PAGE_SIZE-readlen);
440 }
441 SetPageUptodate(page);
442 result = 0;
443 }
444 }
445 if (result) {
446 memset(buf, 0, PAGE_SIZE);
447 SetPageError(page);
448 }
449 flush_dcache_page(page);
450
451 unlock_page(page);
452
453 kunmap(page);
454 err_out:
455 page_cache_release(page);
456 unlock_kernel();
457
458 return result;
459 }
460
461 #ifdef CONFIG_MAGIC_ROM_PTR
462 static int
463 romfs_romptr(struct file * filp, struct vm_area_struct * vma)
464 {
465 struct inode * inode = filp->f_dentry->d_inode;
466 struct romfs_inode_info * romfs_inode = ROMFS_I(inode);
467 struct super_block * sb = filp->f_dentry->d_sb;
468
469 vma->vm_pgoff += romfs_inode->i_dataoffset >> PAGE_SHIFT;
470
471 if ((vma->vm_flags & VM_WRITE) || bromptr(sb->s_bdev, vma))
472 return -ENOSYS;
473
474 vma->vm_start += (romfs_inode->i_dataoffset & ~PAGE_MASK);
475
476 return 0;
477 }
478 #endif
479
480 /* Mapping from our types to the kernel */
481
482 static struct address_space_operations romfs_aops = {
483 .readpage = romfs_readpage
484 };
485
486 static struct file_operations romfs_dir_operations = {
487 .read = generic_read_dir,
488 .readdir = romfs_readdir,
489 };
490
491 struct file_operations romfs_file_operations = {
492 read: generic_file_read,
493 mmap: generic_file_mmap,
494 #ifdef CONFIG_MAGIC_ROM_PTR
495 romptr: romfs_romptr,
496 #endif
497 };
498
499 static struct inode_operations romfs_dir_inode_operations = {
500 .lookup = romfs_lookup,
501 };
502
503 static mode_t romfs_modemap[] =
504 {
505 0, S_IFDIR+0644, S_IFREG+0644, S_IFLNK+0777,
506 S_IFBLK+0600, S_IFCHR+0600, S_IFSOCK+0644, S_IFIFO+0644
507 };
508
509 static void
510 romfs_read_inode(struct inode *i)
511 {
512 int nextfh, ino;
513 struct romfs_inode ri;
514
515 ino = i->i_ino & ROMFH_MASK;
516 i->i_mode = 0;
517 /* Loop for finding the real hard link */
518 for(;;) {
519 if (romfs_copyfrom(i, &ri, ino, ROMFH_SIZE) <= 0) {
520 printk("romfs: read error for inode 0x%x\n", ino);
521 return;
522 }
523 /* XXX: do romfs_checksum here too (with name) */
524
525 nextfh = be32_to_cpu(ri.next);
526 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
527 break;
528
529 ino = be32_to_cpu(ri.spec) & ROMFH_MASK;
530 }
531
532 i->i_nlink = 1; /* Hard to decide.. */
533 i->i_size = be32_to_cpu(ri.size);
534 i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
535 i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
536 i->i_uid = i->i_gid = 0;
537
538 /* Precalculate the data offset */
539 ino = romfs_strnlen(i, ino+ROMFH_SIZE, ROMFS_MAXFN);
540 if (ino >= 0)
541 ino = ((ROMFH_SIZE+ino+1+ROMFH_PAD)&ROMFH_MASK);
542 else
543 ino = 0;
544
545 ROMFS_I(i)->i_metasize = ino;
546 ROMFS_I(i)->i_dataoffset = ino+(i->i_ino&ROMFH_MASK);
547
548 /* Compute permissions */
549 ino = romfs_modemap[nextfh & ROMFH_TYPE];
550 /* only "normal" files have ops */
551 switch (nextfh & ROMFH_TYPE) {
552 case 1:
553 i->i_size = ROMFS_I(i)->i_metasize;
554 i->i_op = &romfs_dir_inode_operations;
555 i->i_fop = &romfs_dir_operations;
556 if (nextfh & ROMFH_EXEC)
557 ino |= S_IXUGO;
558 i->i_mode = ino;
559 break;
560 case 2:
561 i->i_fop = &romfs_file_operations;
562 i->i_data.a_ops = &romfs_aops;
563 if (nextfh & ROMFH_EXEC)
564 ino |= S_IXUGO;
565 i->i_mode = ino;
566 break;
567 case 3:
568 i->i_op = &page_symlink_inode_operations;
569 i->i_data.a_ops = &romfs_aops;
570 i->i_mode = ino | S_IRWXUGO;
571 break;
572 default:
573 /* depending on MBZ for sock/fifos */
574 nextfh = be32_to_cpu(ri.spec);
575 init_special_inode(i, ino,
576 MKDEV(nextfh>>16,nextfh&0xffff));
577 }
578 }
579
580 static kmem_cache_t * romfs_inode_cachep;
581
582 static struct inode *romfs_alloc_inode(struct super_block *sb)
583 {
584 struct romfs_inode_info *ei;
585 ei = (struct romfs_inode_info *)kmem_cache_alloc(romfs_inode_cachep, SLAB_KERNEL);
586 if (!ei)
587 return NULL;
588 return &ei->vfs_inode;
589 }
590
591 static void romfs_destroy_inode(struct inode *inode)
592 {
593 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
594 }
595
596 static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
597 {
598 struct romfs_inode_info *ei = (struct romfs_inode_info *) foo;
599
600 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
601 SLAB_CTOR_CONSTRUCTOR)
602 inode_init_once(&ei->vfs_inode);
603 }
604
605 static int init_inodecache(void)
606 {
607 romfs_inode_cachep = kmem_cache_create("romfs_inode_cache",
608 sizeof(struct romfs_inode_info),
609 0, SLAB_RECLAIM_ACCOUNT,
610 init_once, NULL);
611 if (romfs_inode_cachep == NULL)
612 return -ENOMEM;
613 return 0;
614 }
615
616 static void destroy_inodecache(void)
617 {
618 if (kmem_cache_destroy(romfs_inode_cachep))
619 printk(KERN_INFO "romfs_inode_cache: not all structures were freed\n");
620 }
621
622 static int romfs_remount(struct super_block *sb, int *flags, char *data)
623 {
624 *flags |= MS_RDONLY;
625 return 0;
626 }
627
628 static struct super_operations romfs_ops = {
629 .alloc_inode = romfs_alloc_inode,
630 .destroy_inode = romfs_destroy_inode,
631 .read_inode = romfs_read_inode,
632 .statfs = romfs_statfs,
633 .remount_fs = romfs_remount,
634 };
635
636 static struct super_block *romfs_get_sb(struct file_system_type *fs_type,
637 int flags, const char *dev_name, void *data)
638 {
639 return get_sb_bdev(fs_type, flags, dev_name, data, romfs_fill_super);
640 }
641
642 static struct file_system_type romfs_fs_type = {
643 .owner = THIS_MODULE,
644 .name = "romfs",
645 .get_sb = romfs_get_sb,
646 .kill_sb = kill_block_super,
647 .fs_flags = FS_REQUIRES_DEV,
648 };
649
650 static int __init init_romfs_fs(void)
651 {
652 int err = init_inodecache();
653 if (err)
654 goto out1;
655 err = register_filesystem(&romfs_fs_type);
656 if (err)
657 goto out;
658 return 0;
659 out:
660 destroy_inodecache();
661 out1:
662 return err;
663 }
664
665 static void __exit exit_romfs_fs(void)
666 {
667 unregister_filesystem(&romfs_fs_type);
668 destroy_inodecache();
669 }
670
671 /* Yes, works even as a module... :) */
672
673 module_init(init_romfs_fs)
674 module_exit(exit_romfs_fs)
675 MODULE_LICENSE("GPL");
MOXA 2.6.9 from sdlinux-moxaart.tgz