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update checkpatch.pl to version 0.13
[linux-2.6/x86.git] / fs / romfs / inode.c
blob00b6f0a518c87eab6d5382057d3e514e8d779f6b
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 static struct inode *romfs_iget(struct super_block *, unsigned long);
88
89 /* instead of private superblock data */
90 static inline unsigned long romfs_maxsize(struct super_block *sb)
91 {
92 return (unsigned long)sb->s_fs_info;
93 }
94
95 static inline struct romfs_inode_info *ROMFS_I(struct inode *inode)
96 {
97 return container_of(inode, struct romfs_inode_info, vfs_inode);
98 }
99
100 static __u32
101 romfs_checksum(void *data, int size)
102 {
103 __u32 sum;
104 __be32 *ptr;
105
106 sum = 0; ptr = data;
107 size>>=2;
108 while (size>0) {
109 sum += be32_to_cpu(*ptr++);
110 size--;
111 }
112 return sum;
113 }
114
115 static const struct super_operations romfs_ops;
116
117 static int romfs_fill_super(struct super_block *s, void *data, int silent)
118 {
119 struct buffer_head *bh;
120 struct romfs_super_block *rsb;
121 struct inode *root;
122 int sz, ret = -EINVAL;
123
124 /* I would parse the options here, but there are none.. :) */
125
126 sb_set_blocksize(s, ROMBSIZE);
127 s->s_maxbytes = 0xFFFFFFFF;
128
129 bh = sb_bread(s, 0);
130 if (!bh) {
131 /* XXX merge with other printk? */
132 printk ("romfs: unable to read superblock\n");
133 goto outnobh;
134 }
135
136 rsb = (struct romfs_super_block *)bh->b_data;
137 sz = be32_to_cpu(rsb->size);
138 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1
139 || sz < ROMFH_SIZE) {
140 if (!silent)
141 printk ("VFS: Can't find a romfs filesystem on dev "
142 "%s.\n", s->s_id);
143 goto out;
144 }
145 if (romfs_checksum(rsb, min_t(int, sz, 512))) {
146 printk ("romfs: bad initial checksum on dev "
147 "%s.\n", s->s_id);
148 goto out;
149 }
150
151 s->s_magic = ROMFS_MAGIC;
152 s->s_fs_info = (void *)(long)sz;
153
154 s->s_flags |= MS_RDONLY;
155
156 /* Find the start of the fs */
157 sz = (ROMFH_SIZE +
158 strnlen(rsb->name, ROMFS_MAXFN) + 1 + ROMFH_PAD)
159 & ROMFH_MASK;
160
161 s->s_op = &romfs_ops;
162 root = romfs_iget(s, sz);
163 if (IS_ERR(root)) {
164 ret = PTR_ERR(root);
165 goto out;
166 }
167
168 ret = -ENOMEM;
169 s->s_root = d_alloc_root(root);
170 if (!s->s_root)
171 goto outiput;
172
173 brelse(bh);
174 return 0;
175
176 outiput:
177 iput(root);
178 out:
179 brelse(bh);
180 outnobh:
181 return ret;
182 }
183
184 /* That's simple too. */
185
186 static int
187 romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
188 {
189 buf->f_type = ROMFS_MAGIC;
190 buf->f_bsize = ROMBSIZE;
191 buf->f_bfree = buf->f_bavail = buf->f_ffree;
192 buf->f_blocks = (romfs_maxsize(dentry->d_sb)+ROMBSIZE-1)>>ROMBSBITS;
193 buf->f_namelen = ROMFS_MAXFN;
194 return 0;
195 }
196
197 /* some helper routines */
198
199 static int
200 romfs_strnlen(struct inode *i, unsigned long offset, unsigned long count)
201 {
202 struct buffer_head *bh;
203 unsigned long avail, maxsize, res;
204
205 maxsize = romfs_maxsize(i->i_sb);
206 if (offset >= maxsize)
207 return -1;
208
209 /* strnlen is almost always valid */
210 if (count > maxsize || offset+count > maxsize)
211 count = maxsize-offset;
212
213 bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
214 if (!bh)
215 return -1; /* error */
216
217 avail = ROMBSIZE - (offset & ROMBMASK);
218 maxsize = min_t(unsigned long, count, avail);
219 res = strnlen(((char *)bh->b_data)+(offset&ROMBMASK), maxsize);
220 brelse(bh);
221
222 if (res < maxsize)
223 return res; /* found all of it */
224
225 while (res < count) {
226 offset += maxsize;
227
228 bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
229 if (!bh)
230 return -1;
231 maxsize = min_t(unsigned long, count - res, ROMBSIZE);
232 avail = strnlen(bh->b_data, maxsize);
233 res += avail;
234 brelse(bh);
235 if (avail < maxsize)
236 return res;
237 }
238 return res;
239 }
240
241 static int
242 romfs_copyfrom(struct inode *i, void *dest, unsigned long offset, unsigned long count)
243 {
244 struct buffer_head *bh;
245 unsigned long avail, maxsize, res;
246
247 maxsize = romfs_maxsize(i->i_sb);
248 if (offset >= maxsize || count > maxsize || offset+count>maxsize)
249 return -1;
250
251 bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
252 if (!bh)
253 return -1; /* error */
254
255 avail = ROMBSIZE - (offset & ROMBMASK);
256 maxsize = min_t(unsigned long, count, avail);
257 memcpy(dest, ((char *)bh->b_data) + (offset & ROMBMASK), maxsize);
258 brelse(bh);
259
260 res = maxsize; /* all of it */
261
262 while (res < count) {
263 offset += maxsize;
264 dest += maxsize;
265
266 bh = sb_bread(i->i_sb, offset>>ROMBSBITS);
267 if (!bh)
268 return -1;
269 maxsize = min_t(unsigned long, count - res, ROMBSIZE);
270 memcpy(dest, bh->b_data, maxsize);
271 brelse(bh);
272 res += maxsize;
273 }
274 return res;
275 }
276
277 static unsigned char romfs_dtype_table[] = {
278 DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
279 };
280
281 static int
282 romfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
283 {
284 struct inode *i = filp->f_path.dentry->d_inode;
285 struct romfs_inode ri;
286 unsigned long offset, maxoff;
287 int j, ino, nextfh;
288 int stored = 0;
289 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
290
291 lock_kernel();
292
293 maxoff = romfs_maxsize(i->i_sb);
294
295 offset = filp->f_pos;
296 if (!offset) {
297 offset = i->i_ino & ROMFH_MASK;
298 if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 0)
299 goto out;
300 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
301 }
302
303 /* Not really failsafe, but we are read-only... */
304 for(;;) {
305 if (!offset || offset >= maxoff) {
306 offset = maxoff;
307 filp->f_pos = offset;
308 goto out;
309 }
310 filp->f_pos = offset;
311
312 /* Fetch inode info */
313 if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 0)
314 goto out;
315
316 j = romfs_strnlen(i, offset+ROMFH_SIZE, sizeof(fsname)-1);
317 if (j < 0)
318 goto out;
319
320 fsname[j]=0;
321 romfs_copyfrom(i, fsname, offset+ROMFH_SIZE, j);
322
323 ino = offset;
324 nextfh = be32_to_cpu(ri.next);
325 if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
326 ino = be32_to_cpu(ri.spec);
327 if (filldir(dirent, fsname, j, offset, ino,
328 romfs_dtype_table[nextfh & ROMFH_TYPE]) < 0) {
329 goto out;
330 }
331 stored++;
332 offset = nextfh & ROMFH_MASK;
333 }
334 out:
335 unlock_kernel();
336 return stored;
337 }
338
339 static struct dentry *
340 romfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
341 {
342 unsigned long offset, maxoff;
343 int fslen, res;
344 struct inode *inode;
345 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
346 struct romfs_inode ri;
347 const char *name; /* got from dentry */
348 int len;
349
350 res = -EACCES; /* placeholder for "no data here" */
351 offset = dir->i_ino & ROMFH_MASK;
352 lock_kernel();
353 if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
354 goto out;
355
356 maxoff = romfs_maxsize(dir->i_sb);
357 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
358
359 /* OK, now find the file whose name is in "dentry" in the
360 * directory specified by "dir". */
361
362 name = dentry->d_name.name;
363 len = dentry->d_name.len;
364
365 for(;;) {
366 if (!offset || offset >= maxoff)
367 goto out0;
368 if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
369 goto out;
370
371 /* try to match the first 16 bytes of name */
372 fslen = romfs_strnlen(dir, offset+ROMFH_SIZE, ROMFH_SIZE);
373 if (len < ROMFH_SIZE) {
374 if (len == fslen) {
375 /* both are shorter, and same size */
376 romfs_copyfrom(dir, fsname, offset+ROMFH_SIZE, len+1);
377 if (strncmp (name, fsname, len) == 0)
378 break;
379 }
380 } else if (fslen >= ROMFH_SIZE) {
381 /* both are longer; XXX optimize max size */
382 fslen = romfs_strnlen(dir, offset+ROMFH_SIZE, sizeof(fsname)-1);
383 if (len == fslen) {
384 romfs_copyfrom(dir, fsname, offset+ROMFH_SIZE, len+1);
385 if (strncmp(name, fsname, len) == 0)
386 break;
387 }
388 }
389 /* next entry */
390 offset = be32_to_cpu(ri.next) & ROMFH_MASK;
391 }
392
393 /* Hard link handling */
394 if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
395 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
396
397 inode = romfs_iget(dir->i_sb, offset);
398 if (IS_ERR(inode)) {
399 res = PTR_ERR(inode);
400 goto out;
401 }
402
403 /*
404 * it's a bit funky, _lookup needs to return an error code
405 * (negative) or a NULL, both as a dentry. ENOENT should not
406 * be returned, instead we need to create a negative dentry by
407 * d_add(dentry, NULL); and return 0 as no error.
408 * (Although as I see, it only matters on writable file
409 * systems).
410 */
411
412 out0: inode = NULL;
413 res = 0;
414 d_add (dentry, inode);
415
416 out: unlock_kernel();
417 return ERR_PTR(res);
418 }
419
420 /*
421 * Ok, we do readpage, to be able to execute programs. Unfortunately,
422 * we can't use bmap, since we may have looser alignments.
423 */
424
425 static int
426 romfs_readpage(struct file *file, struct page * page)
427 {
428 struct inode *inode = page->mapping->host;
429 loff_t offset, avail, readlen;
430 void *buf;
431 int result = -EIO;
432
433 page_cache_get(page);
434 lock_kernel();
435 buf = kmap(page);
436 if (!buf)
437 goto err_out;
438
439 /* 32 bit warning -- but not for us :) */
440 offset = page_offset(page);
441 if (offset < i_size_read(inode)) {
442 avail = inode->i_size-offset;
443 readlen = min_t(unsigned long, avail, PAGE_SIZE);
444 if (romfs_copyfrom(inode, buf, ROMFS_I(inode)->i_dataoffset+offset, readlen) == readlen) {
445 if (readlen < PAGE_SIZE) {
446 memset(buf + readlen,0,PAGE_SIZE-readlen);
447 }
448 SetPageUptodate(page);
449 result = 0;
450 }
451 }
452 if (result) {
453 memset(buf, 0, PAGE_SIZE);
454 SetPageError(page);
455 }
456 flush_dcache_page(page);
457
458 unlock_page(page);
459
460 kunmap(page);
461 err_out:
462 page_cache_release(page);
463 unlock_kernel();
464
465 return result;
466 }
467
468 /* Mapping from our types to the kernel */
469
470 static const struct address_space_operations romfs_aops = {
471 .readpage = romfs_readpage
472 };
473
474 static const struct file_operations romfs_dir_operations = {
475 .read = generic_read_dir,
476 .readdir = romfs_readdir,
477 };
478
479 static const struct inode_operations romfs_dir_inode_operations = {
480 .lookup = romfs_lookup,
481 };
482
483 static mode_t romfs_modemap[] =
484 {
485 0, S_IFDIR+0644, S_IFREG+0644, S_IFLNK+0777,
486 S_IFBLK+0600, S_IFCHR+0600, S_IFSOCK+0644, S_IFIFO+0644
487 };
488
489 static struct inode *
490 romfs_iget(struct super_block *sb, unsigned long ino)
491 {
492 int nextfh;
493 struct romfs_inode ri;
494 struct inode *i;
495
496 ino &= ROMFH_MASK;
497 i = iget_locked(sb, ino);
498 if (!i)
499 return ERR_PTR(-ENOMEM);
500 if (!(i->i_state & I_NEW))
501 return i;
502
503 i->i_mode = 0;
504
505 /* Loop for finding the real hard link */
506 for(;;) {
507 if (romfs_copyfrom(i, &ri, ino, ROMFH_SIZE) <= 0) {
508 printk(KERN_ERR "romfs: read error for inode 0x%lx\n",
509 ino);
510 iget_failed(i);
511 return ERR_PTR(-EIO);
512 }
513 /* XXX: do romfs_checksum here too (with name) */
514
515 nextfh = be32_to_cpu(ri.next);
516 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
517 break;
518
519 ino = be32_to_cpu(ri.spec) & ROMFH_MASK;
520 }
521
522 i->i_nlink = 1; /* Hard to decide.. */
523 i->i_size = be32_to_cpu(ri.size);
524 i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
525 i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
526 i->i_uid = i->i_gid = 0;
527
528 /* Precalculate the data offset */
529 ino = romfs_strnlen(i, ino+ROMFH_SIZE, ROMFS_MAXFN);
530 if (ino >= 0)
531 ino = ((ROMFH_SIZE+ino+1+ROMFH_PAD)&ROMFH_MASK);
532 else
533 ino = 0;
534
535 ROMFS_I(i)->i_metasize = ino;
536 ROMFS_I(i)->i_dataoffset = ino+(i->i_ino&ROMFH_MASK);
537
538 /* Compute permissions */
539 ino = romfs_modemap[nextfh & ROMFH_TYPE];
540 /* only "normal" files have ops */
541 switch (nextfh & ROMFH_TYPE) {
542 case 1:
543 i->i_size = ROMFS_I(i)->i_metasize;
544 i->i_op = &romfs_dir_inode_operations;
545 i->i_fop = &romfs_dir_operations;
546 if (nextfh & ROMFH_EXEC)
547 ino |= S_IXUGO;
548 i->i_mode = ino;
549 break;
550 case 2:
551 i->i_fop = &generic_ro_fops;
552 i->i_data.a_ops = &romfs_aops;
553 if (nextfh & ROMFH_EXEC)
554 ino |= S_IXUGO;
555 i->i_mode = ino;
556 break;
557 case 3:
558 i->i_op = &page_symlink_inode_operations;
559 i->i_data.a_ops = &romfs_aops;
560 i->i_mode = ino | S_IRWXUGO;
561 break;
562 default:
563 /* depending on MBZ for sock/fifos */
564 nextfh = be32_to_cpu(ri.spec);
565 init_special_inode(i, ino,
566 MKDEV(nextfh>>16,nextfh&0xffff));
567 }
568 unlock_new_inode(i);
569 return i;
570 }
571
572 static struct kmem_cache * romfs_inode_cachep;
573
574 static struct inode *romfs_alloc_inode(struct super_block *sb)
575 {
576 struct romfs_inode_info *ei;
577 ei = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
578 if (!ei)
579 return NULL;
580 return &ei->vfs_inode;
581 }
582
583 static void romfs_destroy_inode(struct inode *inode)
584 {
585 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
586 }
587
588 static void init_once(struct kmem_cache *cachep, void *foo)
589 {
590 struct romfs_inode_info *ei = foo;
591
592 inode_init_once(&ei->vfs_inode);
593 }
594
595 static int init_inodecache(void)
596 {
597 romfs_inode_cachep = kmem_cache_create("romfs_inode_cache",
598 sizeof(struct romfs_inode_info),
599 0, (SLAB_RECLAIM_ACCOUNT|
600 SLAB_MEM_SPREAD),
601 init_once);
602 if (romfs_inode_cachep == NULL)
603 return -ENOMEM;
604 return 0;
605 }
606
607 static void destroy_inodecache(void)
608 {
609 kmem_cache_destroy(romfs_inode_cachep);
610 }
611
612 static int romfs_remount(struct super_block *sb, int *flags, char *data)
613 {
614 *flags |= MS_RDONLY;
615 return 0;
616 }
617
618 static const struct super_operations romfs_ops = {
619 .alloc_inode = romfs_alloc_inode,
620 .destroy_inode = romfs_destroy_inode,
621 .statfs = romfs_statfs,
622 .remount_fs = romfs_remount,
623 };
624
625 static int romfs_get_sb(struct file_system_type *fs_type,
626 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
627 {
628 return get_sb_bdev(fs_type, flags, dev_name, data, romfs_fill_super,
629 mnt);
630 }
631
632 static struct file_system_type romfs_fs_type = {
633 .owner = THIS_MODULE,
634 .name = "romfs",
635 .get_sb = romfs_get_sb,
636 .kill_sb = kill_block_super,
637 .fs_flags = FS_REQUIRES_DEV,
638 };
639
640 static int __init init_romfs_fs(void)
641 {
642 int err = init_inodecache();
643 if (err)
644 goto out1;
645 err = register_filesystem(&romfs_fs_type);
646 if (err)
647 goto out;
648 return 0;
649 out:
650 destroy_inodecache();
651 out1:
652 return err;
653 }
654
655 static void __exit exit_romfs_fs(void)
656 {
657 unregister_filesystem(&romfs_fs_type);
658 destroy_inodecache();
659 }
660
661 /* Yes, works even as a module... :) */
662
663 module_init(init_romfs_fs)
664 module_exit(exit_romfs_fs)
665 MODULE_LICENSE("GPL");
x86 "subsystem" repository