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da4458bd
DH
1/* Block- or MTD-based romfs
2 *
3 * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * Derived from: ROMFS file system, Linux implementation
7 *
8 * Copyright © 1997-1999 Janos Farkas <chexum@shadow.banki.hu>
9 *
10 * Using parts of the minix filesystem
11 * Copyright © 1991, 1992 Linus Torvalds
12 *
13 * and parts of the affs filesystem additionally
14 * Copyright © 1993 Ray Burr
15 * Copyright © 1996 Hans-Joachim Widmaier
16 *
17 * Changes
18 * Changed for 2.1.19 modules
19 * Jan 1997 Initial release
20 * Jun 1997 2.1.43+ changes
21 * Proper page locking in readpage
22 * Changed to work with 2.1.45+ fs
23 * Jul 1997 Fixed follow_link
24 * 2.1.47
25 * lookup shouldn't return -ENOENT
26 * from Horst von Brand:
27 * fail on wrong checksum
28 * double unlock_super was possible
29 * correct namelen for statfs
30 * spotted by Bill Hawes:
31 * readlink shouldn't iput()
32 * Jun 1998 2.1.106 from Avery Pennarun: glibc scandir()
33 * exposed a problem in readdir
34 * 2.1.107 code-freeze spellchecker run
35 * Aug 1998 2.1.118+ VFS changes
36 * Sep 1998 2.1.122 another VFS change (follow_link)
37 * Apr 1999 2.2.7 no more EBADF checking in
38 * lookup/readdir, use ERR_PTR
39 * Jun 1999 2.3.6 d_alloc_root use changed
40 * 2.3.9 clean up usage of ENOENT/negative
41 * dentries in lookup
42 * clean up page flags setting
43 * (error, uptodate, locking) in
44 * in readpage
45 * use init_special_inode for
46 * fifos/sockets (and streamline) in
47 * read_inode, fix _ops table order
48 * Aug 1999 2.3.16 __initfunc() => __init change
49 * Oct 1999 2.3.24 page->owner hack obsoleted
50 * Nov 1999 2.3.27 2.3.25+ page->offset => index change
51 *
52 *
53 * This program is free software; you can redistribute it and/or
54 * modify it under the terms of the GNU General Public Licence
55 * as published by the Free Software Foundation; either version
56 * 2 of the Licence, or (at your option) any later version.
57 */
58
59#include <linux/module.h>
60#include <linux/string.h>
61#include <linux/fs.h>
62#include <linux/time.h>
63#include <linux/slab.h>
64#include <linux/init.h>
65#include <linux/blkdev.h>
66#include <linux/parser.h>
67#include <linux/mount.h>
68#include <linux/namei.h>
69#include <linux/statfs.h>
70#include <linux/mtd/super.h>
71#include <linux/ctype.h>
72#include <linux/highmem.h>
73#include <linux/pagemap.h>
74#include <linux/uaccess.h>
75#include "internal.h"
76
77static struct kmem_cache *romfs_inode_cachep;
78
79static const umode_t romfs_modemap[8] = {
80 0, /* hard link */
81 S_IFDIR | 0644, /* directory */
82 S_IFREG | 0644, /* regular file */
83 S_IFLNK | 0777, /* symlink */
84 S_IFBLK | 0600, /* blockdev */
85 S_IFCHR | 0600, /* chardev */
86 S_IFSOCK | 0644, /* socket */
87 S_IFIFO | 0644 /* FIFO */
88};
89
90static const unsigned char romfs_dtype_table[] = {
91 DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
92};
93
94static struct inode *romfs_iget(struct super_block *sb, unsigned long pos);
95
96/*
97 * read a page worth of data from the image
98 */
99static int romfs_readpage(struct file *file, struct page *page)
100{
101 struct inode *inode = page->mapping->host;
102 loff_t offset, size;
103 unsigned long fillsize, pos;
104 void *buf;
105 int ret;
106
107 buf = kmap(page);
108 if (!buf)
109 return -ENOMEM;
110
111 /* 32 bit warning -- but not for us :) */
112 offset = page_offset(page);
113 size = i_size_read(inode);
114 fillsize = 0;
115 ret = 0;
116 if (offset < size) {
117 size -= offset;
118 fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;
119
120 pos = ROMFS_I(inode)->i_dataoffset + offset;
121
122 ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
123 if (ret < 0) {
124 SetPageError(page);
125 fillsize = 0;
126 ret = -EIO;
127 }
128 }
129
130 if (fillsize < PAGE_SIZE)
131 memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
132 if (ret == 0)
133 SetPageUptodate(page);
134
135 flush_dcache_page(page);
136 kunmap(page);
137 unlock_page(page);
138 return ret;
139}
140
141static const struct address_space_operations romfs_aops = {
142 .readpage = romfs_readpage
143};
144
145/*
146 * read the entries from a directory
147 */
3903b38c 148static int romfs_readdir(struct file *file, struct dir_context *ctx)
da4458bd 149{
3903b38c 150 struct inode *i = file_inode(file);
da4458bd
DH
151 struct romfs_inode ri;
152 unsigned long offset, maxoff;
153 int j, ino, nextfh;
da4458bd
DH
154 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
155 int ret;
156
157 maxoff = romfs_maxsize(i->i_sb);
158
3903b38c 159 offset = ctx->pos;
da4458bd
DH
160 if (!offset) {
161 offset = i->i_ino & ROMFH_MASK;
162 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
163 if (ret < 0)
164 goto out;
165 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
166 }
167
168 /* Not really failsafe, but we are read-only... */
169 for (;;) {
170 if (!offset || offset >= maxoff) {
171 offset = maxoff;
3903b38c 172 ctx->pos = offset;
da4458bd
DH
173 goto out;
174 }
3903b38c 175 ctx->pos = offset;
da4458bd
DH
176
177 /* Fetch inode info */
178 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
179 if (ret < 0)
180 goto out;
181
182 j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
183 sizeof(fsname) - 1);
184 if (j < 0)
185 goto out;
186
187 ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
188 if (ret < 0)
189 goto out;
190 fsname[j] = '\0';
191
192 ino = offset;
193 nextfh = be32_to_cpu(ri.next);
194 if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
195 ino = be32_to_cpu(ri.spec);
3903b38c
AV
196 if (!dir_emit(ctx, fsname, j, ino,
197 romfs_dtype_table[nextfh & ROMFH_TYPE]))
da4458bd
DH
198 goto out;
199
da4458bd
DH
200 offset = nextfh & ROMFH_MASK;
201 }
da4458bd 202out:
3903b38c 203 return 0;
da4458bd
DH
204}
205
206/*
207 * look up an entry in a directory
208 */
209static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry,
00cd8dd3 210 unsigned int flags)
da4458bd
DH
211{
212 unsigned long offset, maxoff;
213 struct inode *inode;
214 struct romfs_inode ri;
215 const char *name; /* got from dentry */
216 int len, ret;
217
218 offset = dir->i_ino & ROMFH_MASK;
219 ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
220 if (ret < 0)
221 goto error;
222
223 /* search all the file entries in the list starting from the one
224 * pointed to by the directory's special data */
225 maxoff = romfs_maxsize(dir->i_sb);
226 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
227
228 name = dentry->d_name.name;
229 len = dentry->d_name.len;
230
231 for (;;) {
232 if (!offset || offset >= maxoff)
233 goto out0;
234
235 ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
236 if (ret < 0)
237 goto error;
238
239 /* try to match the first 16 bytes of name */
84baf74b
DH
240 ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
241 len);
da4458bd
DH
242 if (ret < 0)
243 goto error;
244 if (ret == 1)
245 break;
246
247 /* next entry */
248 offset = be32_to_cpu(ri.next) & ROMFH_MASK;
249 }
250
251 /* Hard link handling */
252 if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
253 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
254
255 inode = romfs_iget(dir->i_sb, offset);
256 if (IS_ERR(inode)) {
257 ret = PTR_ERR(inode);
258 goto error;
259 }
260 goto outi;
261
262 /*
263 * it's a bit funky, _lookup needs to return an error code
264 * (negative) or a NULL, both as a dentry. ENOENT should not
265 * be returned, instead we need to create a negative dentry by
266 * d_add(dentry, NULL); and return 0 as no error.
267 * (Although as I see, it only matters on writable file
268 * systems).
269 */
270out0:
271 inode = NULL;
272outi:
273 d_add(dentry, inode);
274 ret = 0;
275error:
276 return ERR_PTR(ret);
277}
278
279static const struct file_operations romfs_dir_operations = {
280 .read = generic_read_dir,
3903b38c 281 .iterate = romfs_readdir,
6038f373 282 .llseek = default_llseek,
da4458bd
DH
283};
284
6e1d5dcc 285static const struct inode_operations romfs_dir_inode_operations = {
da4458bd
DH
286 .lookup = romfs_lookup,
287};
288
289/*
290 * get a romfs inode based on its position in the image (which doubles as the
291 * inode number)
292 */
293static struct inode *romfs_iget(struct super_block *sb, unsigned long pos)
294{
295 struct romfs_inode_info *inode;
296 struct romfs_inode ri;
297 struct inode *i;
298 unsigned long nlen;
774e33e7
RK
299 unsigned nextfh;
300 int ret;
da4458bd
DH
301 umode_t mode;
302
303 /* we might have to traverse a chain of "hard link" file entries to get
304 * to the actual file */
305 for (;;) {
306 ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
307 if (ret < 0)
308 goto error;
309
310 /* XXX: do romfs_checksum here too (with name) */
311
312 nextfh = be32_to_cpu(ri.next);
313 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
314 break;
315
316 pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
317 }
318
319 /* determine the length of the filename */
320 nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
321 if (IS_ERR_VALUE(nlen))
322 goto eio;
323
324 /* get an inode for this image position */
325 i = iget_locked(sb, pos);
326 if (!i)
327 return ERR_PTR(-ENOMEM);
328
329 if (!(i->i_state & I_NEW))
330 return i;
331
332 /* precalculate the data offset */
333 inode = ROMFS_I(i);
334 inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
335 inode->i_dataoffset = pos + inode->i_metasize;
336
bfe86848 337 set_nlink(i, 1); /* Hard to decide.. */
da4458bd
DH
338 i->i_size = be32_to_cpu(ri.size);
339 i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
340 i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
341
342 /* set up mode and ops */
343 mode = romfs_modemap[nextfh & ROMFH_TYPE];
344
345 switch (nextfh & ROMFH_TYPE) {
346 case ROMFH_DIR:
347 i->i_size = ROMFS_I(i)->i_metasize;
348 i->i_op = &romfs_dir_inode_operations;
349 i->i_fop = &romfs_dir_operations;
350 if (nextfh & ROMFH_EXEC)
351 mode |= S_IXUGO;
352 break;
353 case ROMFH_REG:
354 i->i_fop = &romfs_ro_fops;
355 i->i_data.a_ops = &romfs_aops;
356 if (i->i_sb->s_mtd)
357 i->i_data.backing_dev_info =
358 i->i_sb->s_mtd->backing_dev_info;
359 if (nextfh & ROMFH_EXEC)
360 mode |= S_IXUGO;
361 break;
362 case ROMFH_SYM:
363 i->i_op = &page_symlink_inode_operations;
364 i->i_data.a_ops = &romfs_aops;
365 mode |= S_IRWXUGO;
366 break;
367 default:
368 /* depending on MBZ for sock/fifos */
369 nextfh = be32_to_cpu(ri.spec);
370 init_special_inode(i, mode, MKDEV(nextfh >> 16,
371 nextfh & 0xffff));
372 break;
373 }
374
375 i->i_mode = mode;
376
377 unlock_new_inode(i);
378 return i;
379
380eio:
381 ret = -EIO;
382error:
383 printk(KERN_ERR "ROMFS: read error for inode 0x%lx\n", pos);
384 return ERR_PTR(ret);
385}
386
387/*
388 * allocate a new inode
389 */
390static struct inode *romfs_alloc_inode(struct super_block *sb)
391{
392 struct romfs_inode_info *inode;
393 inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
394 return inode ? &inode->vfs_inode : NULL;
395}
396
397/*
398 * return a spent inode to the slab cache
399 */
fa0d7e3d 400static void romfs_i_callback(struct rcu_head *head)
da4458bd 401{
fa0d7e3d 402 struct inode *inode = container_of(head, struct inode, i_rcu);
da4458bd
DH
403 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
404}
405
fa0d7e3d
NP
406static void romfs_destroy_inode(struct inode *inode)
407{
408 call_rcu(&inode->i_rcu, romfs_i_callback);
409}
410
da4458bd
DH
411/*
412 * get filesystem statistics
413 */
414static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
415{
8a59f5d2
CL
416 struct super_block *sb = dentry->d_sb;
417 u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
418
da4458bd
DH
419 buf->f_type = ROMFS_MAGIC;
420 buf->f_namelen = ROMFS_MAXFN;
421 buf->f_bsize = ROMBSIZE;
422 buf->f_bfree = buf->f_bavail = buf->f_ffree;
423 buf->f_blocks =
424 (romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
8a59f5d2
CL
425 buf->f_fsid.val[0] = (u32)id;
426 buf->f_fsid.val[1] = (u32)(id >> 32);
da4458bd
DH
427 return 0;
428}
429
430/*
431 * remounting must involve read-only
432 */
433static int romfs_remount(struct super_block *sb, int *flags, char *data)
434{
435 *flags |= MS_RDONLY;
436 return 0;
437}
438
439static const struct super_operations romfs_super_ops = {
440 .alloc_inode = romfs_alloc_inode,
441 .destroy_inode = romfs_destroy_inode,
442 .statfs = romfs_statfs,
443 .remount_fs = romfs_remount,
444};
445
446/*
447 * checksum check on part of a romfs filesystem
448 */
449static __u32 romfs_checksum(const void *data, int size)
450{
451 const __be32 *ptr = data;
452 __u32 sum;
453
454 sum = 0;
455 size >>= 2;
456 while (size > 0) {
457 sum += be32_to_cpu(*ptr++);
458 size--;
459 }
460 return sum;
461}
462
463/*
464 * fill in the superblock
465 */
466static int romfs_fill_super(struct super_block *sb, void *data, int silent)
467{
468 struct romfs_super_block *rsb;
469 struct inode *root;
470 unsigned long pos, img_size;
471 const char *storage;
472 size_t len;
473 int ret;
474
475#ifdef CONFIG_BLOCK
476 if (!sb->s_mtd) {
477 sb_set_blocksize(sb, ROMBSIZE);
478 } else {
479 sb->s_blocksize = ROMBSIZE;
480 sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
481 }
482#endif
483
484 sb->s_maxbytes = 0xFFFFFFFF;
485 sb->s_magic = ROMFS_MAGIC;
486 sb->s_flags |= MS_RDONLY | MS_NOATIME;
487 sb->s_op = &romfs_super_ops;
488
489 /* read the image superblock and check it */
490 rsb = kmalloc(512, GFP_KERNEL);
491 if (!rsb)
492 return -ENOMEM;
493
494 sb->s_fs_info = (void *) 512;
495 ret = romfs_dev_read(sb, 0, rsb, 512);
496 if (ret < 0)
497 goto error_rsb;
498
499 img_size = be32_to_cpu(rsb->size);
500
501 if (sb->s_mtd && img_size > sb->s_mtd->size)
502 goto error_rsb_inval;
503
504 sb->s_fs_info = (void *) img_size;
505
506 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 ||
507 img_size < ROMFH_SIZE) {
508 if (!silent)
509 printk(KERN_WARNING "VFS:"
510 " Can't find a romfs filesystem on dev %s.\n",
511 sb->s_id);
512 goto error_rsb_inval;
513 }
514
515 if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
516 printk(KERN_ERR "ROMFS: bad initial checksum on dev %s.\n",
517 sb->s_id);
518 goto error_rsb_inval;
519 }
520
521 storage = sb->s_mtd ? "MTD" : "the block layer";
522
523 len = strnlen(rsb->name, ROMFS_MAXFN);
524 if (!silent)
525 printk(KERN_NOTICE "ROMFS: Mounting image '%*.*s' through %s\n",
526 (unsigned) len, (unsigned) len, rsb->name, storage);
527
528 kfree(rsb);
529 rsb = NULL;
530
531 /* find the root directory */
532 pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
533
534 root = romfs_iget(sb, pos);
a21f3c2a 535 if (IS_ERR(root))
40e2c71d 536 return PTR_ERR(root);
da4458bd 537
48fde701 538 sb->s_root = d_make_root(root);
da4458bd 539 if (!sb->s_root)
40e2c71d 540 return -ENOMEM;
da4458bd
DH
541
542 return 0;
543
da4458bd
DH
544error_rsb_inval:
545 ret = -EINVAL;
546error_rsb:
7e32b7bb 547 kfree(rsb);
da4458bd
DH
548 return ret;
549}
550
551/*
552 * get a superblock for mounting
553 */
848b83a5 554static struct dentry *romfs_mount(struct file_system_type *fs_type,
da4458bd 555 int flags, const char *dev_name,
848b83a5 556 void *data)
da4458bd 557{
848b83a5 558 struct dentry *ret = ERR_PTR(-EINVAL);
da4458bd
DH
559
560#ifdef CONFIG_ROMFS_ON_MTD
848b83a5 561 ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super);
da4458bd
DH
562#endif
563#ifdef CONFIG_ROMFS_ON_BLOCK
848b83a5
AV
564 if (ret == ERR_PTR(-EINVAL))
565 ret = mount_bdev(fs_type, flags, dev_name, data,
566 romfs_fill_super);
da4458bd
DH
567#endif
568 return ret;
569}
570
571/*
572 * destroy a romfs superblock in the appropriate manner
573 */
574static void romfs_kill_sb(struct super_block *sb)
575{
576#ifdef CONFIG_ROMFS_ON_MTD
577 if (sb->s_mtd) {
578 kill_mtd_super(sb);
579 return;
580 }
581#endif
582#ifdef CONFIG_ROMFS_ON_BLOCK
583 if (sb->s_bdev) {
584 kill_block_super(sb);
585 return;
586 }
587#endif
588}
589
590static struct file_system_type romfs_fs_type = {
591 .owner = THIS_MODULE,
592 .name = "romfs",
848b83a5 593 .mount = romfs_mount,
da4458bd
DH
594 .kill_sb = romfs_kill_sb,
595 .fs_flags = FS_REQUIRES_DEV,
596};
7f78e035 597MODULE_ALIAS_FS("romfs");
da4458bd
DH
598
599/*
600 * inode storage initialiser
601 */
602static void romfs_i_init_once(void *_inode)
603{
604 struct romfs_inode_info *inode = _inode;
605
606 inode_init_once(&inode->vfs_inode);
607}
608
609/*
610 * romfs module initialisation
611 */
612static int __init init_romfs_fs(void)
613{
614 int ret;
615
616 printk(KERN_INFO "ROMFS MTD (C) 2007 Red Hat, Inc.\n");
617
618 romfs_inode_cachep =
619 kmem_cache_create("romfs_i",
620 sizeof(struct romfs_inode_info), 0,
621 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
622 romfs_i_init_once);
623
624 if (!romfs_inode_cachep) {
625 printk(KERN_ERR
626 "ROMFS error: Failed to initialise inode cache\n");
627 return -ENOMEM;
628 }
629 ret = register_filesystem(&romfs_fs_type);
630 if (ret) {
631 printk(KERN_ERR "ROMFS error: Failed to register filesystem\n");
632 goto error_register;
633 }
634 return 0;
635
636error_register:
637 kmem_cache_destroy(romfs_inode_cachep);
638 return ret;
639}
640
641/*
642 * romfs module removal
643 */
644static void __exit exit_romfs_fs(void)
645{
646 unregister_filesystem(&romfs_fs_type);
8c0a8537
KS
647 /*
648 * Make sure all delayed rcu free inodes are flushed before we
649 * destroy cache.
650 */
651 rcu_barrier();
da4458bd
DH
652 kmem_cache_destroy(romfs_inode_cachep);
653}
654
655module_init(init_romfs_fs);
656module_exit(exit_romfs_fs);
657
658MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
659MODULE_AUTHOR("Red Hat, Inc.");
660MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */