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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
ca9e5368
FF
59#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
60
da4458bd
DH
61#include <linux/module.h>
62#include <linux/string.h>
63#include <linux/fs.h>
64#include <linux/time.h>
65#include <linux/slab.h>
66#include <linux/init.h>
67#include <linux/blkdev.h>
68#include <linux/parser.h>
69#include <linux/mount.h>
70#include <linux/namei.h>
71#include <linux/statfs.h>
72#include <linux/mtd/super.h>
73#include <linux/ctype.h>
74#include <linux/highmem.h>
75#include <linux/pagemap.h>
76#include <linux/uaccess.h>
77#include "internal.h"
78
79static struct kmem_cache *romfs_inode_cachep;
80
81static const umode_t romfs_modemap[8] = {
82 0, /* hard link */
83 S_IFDIR | 0644, /* directory */
84 S_IFREG | 0644, /* regular file */
85 S_IFLNK | 0777, /* symlink */
86 S_IFBLK | 0600, /* blockdev */
87 S_IFCHR | 0600, /* chardev */
88 S_IFSOCK | 0644, /* socket */
89 S_IFIFO | 0644 /* FIFO */
90};
91
92static const unsigned char romfs_dtype_table[] = {
93 DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
94};
95
96static struct inode *romfs_iget(struct super_block *sb, unsigned long pos);
97
98/*
99 * read a page worth of data from the image
100 */
101static int romfs_readpage(struct file *file, struct page *page)
102{
103 struct inode *inode = page->mapping->host;
104 loff_t offset, size;
105 unsigned long fillsize, pos;
106 void *buf;
107 int ret;
108
109 buf = kmap(page);
110 if (!buf)
111 return -ENOMEM;
112
113 /* 32 bit warning -- but not for us :) */
114 offset = page_offset(page);
115 size = i_size_read(inode);
116 fillsize = 0;
117 ret = 0;
118 if (offset < size) {
119 size -= offset;
120 fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;
121
122 pos = ROMFS_I(inode)->i_dataoffset + offset;
123
124 ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
125 if (ret < 0) {
126 SetPageError(page);
127 fillsize = 0;
128 ret = -EIO;
129 }
130 }
131
132 if (fillsize < PAGE_SIZE)
133 memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
134 if (ret == 0)
135 SetPageUptodate(page);
136
137 flush_dcache_page(page);
138 kunmap(page);
139 unlock_page(page);
140 return ret;
141}
142
143static const struct address_space_operations romfs_aops = {
144 .readpage = romfs_readpage
145};
146
147/*
148 * read the entries from a directory
149 */
3903b38c 150static int romfs_readdir(struct file *file, struct dir_context *ctx)
da4458bd 151{
3903b38c 152 struct inode *i = file_inode(file);
da4458bd
DH
153 struct romfs_inode ri;
154 unsigned long offset, maxoff;
155 int j, ino, nextfh;
da4458bd
DH
156 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
157 int ret;
158
159 maxoff = romfs_maxsize(i->i_sb);
160
3903b38c 161 offset = ctx->pos;
da4458bd
DH
162 if (!offset) {
163 offset = i->i_ino & ROMFH_MASK;
164 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
165 if (ret < 0)
166 goto out;
167 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
168 }
169
170 /* Not really failsafe, but we are read-only... */
171 for (;;) {
172 if (!offset || offset >= maxoff) {
173 offset = maxoff;
3903b38c 174 ctx->pos = offset;
da4458bd
DH
175 goto out;
176 }
3903b38c 177 ctx->pos = offset;
da4458bd
DH
178
179 /* Fetch inode info */
180 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
181 if (ret < 0)
182 goto out;
183
184 j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
185 sizeof(fsname) - 1);
186 if (j < 0)
187 goto out;
188
189 ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
190 if (ret < 0)
191 goto out;
192 fsname[j] = '\0';
193
194 ino = offset;
195 nextfh = be32_to_cpu(ri.next);
196 if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
197 ino = be32_to_cpu(ri.spec);
3903b38c
AV
198 if (!dir_emit(ctx, fsname, j, ino,
199 romfs_dtype_table[nextfh & ROMFH_TYPE]))
da4458bd
DH
200 goto out;
201
da4458bd
DH
202 offset = nextfh & ROMFH_MASK;
203 }
da4458bd 204out:
3903b38c 205 return 0;
da4458bd
DH
206}
207
208/*
209 * look up an entry in a directory
210 */
211static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry,
00cd8dd3 212 unsigned int flags)
da4458bd
DH
213{
214 unsigned long offset, maxoff;
215 struct inode *inode;
216 struct romfs_inode ri;
217 const char *name; /* got from dentry */
218 int len, ret;
219
220 offset = dir->i_ino & ROMFH_MASK;
221 ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
222 if (ret < 0)
223 goto error;
224
225 /* search all the file entries in the list starting from the one
226 * pointed to by the directory's special data */
227 maxoff = romfs_maxsize(dir->i_sb);
228 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
229
230 name = dentry->d_name.name;
231 len = dentry->d_name.len;
232
233 for (;;) {
234 if (!offset || offset >= maxoff)
235 goto out0;
236
237 ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
238 if (ret < 0)
239 goto error;
240
241 /* try to match the first 16 bytes of name */
84baf74b
DH
242 ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
243 len);
da4458bd
DH
244 if (ret < 0)
245 goto error;
246 if (ret == 1)
247 break;
248
249 /* next entry */
250 offset = be32_to_cpu(ri.next) & ROMFH_MASK;
251 }
252
253 /* Hard link handling */
254 if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
255 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
256
257 inode = romfs_iget(dir->i_sb, offset);
258 if (IS_ERR(inode)) {
259 ret = PTR_ERR(inode);
260 goto error;
261 }
262 goto outi;
263
264 /*
265 * it's a bit funky, _lookup needs to return an error code
266 * (negative) or a NULL, both as a dentry. ENOENT should not
267 * be returned, instead we need to create a negative dentry by
268 * d_add(dentry, NULL); and return 0 as no error.
269 * (Although as I see, it only matters on writable file
270 * systems).
271 */
272out0:
273 inode = NULL;
274outi:
275 d_add(dentry, inode);
276 ret = 0;
277error:
278 return ERR_PTR(ret);
279}
280
281static const struct file_operations romfs_dir_operations = {
282 .read = generic_read_dir,
3903b38c 283 .iterate = romfs_readdir,
6038f373 284 .llseek = default_llseek,
da4458bd
DH
285};
286
6e1d5dcc 287static const struct inode_operations romfs_dir_inode_operations = {
da4458bd
DH
288 .lookup = romfs_lookup,
289};
290
291/*
292 * get a romfs inode based on its position in the image (which doubles as the
293 * inode number)
294 */
295static struct inode *romfs_iget(struct super_block *sb, unsigned long pos)
296{
297 struct romfs_inode_info *inode;
298 struct romfs_inode ri;
299 struct inode *i;
300 unsigned long nlen;
774e33e7
RK
301 unsigned nextfh;
302 int ret;
da4458bd
DH
303 umode_t mode;
304
305 /* we might have to traverse a chain of "hard link" file entries to get
306 * to the actual file */
307 for (;;) {
308 ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
309 if (ret < 0)
310 goto error;
311
312 /* XXX: do romfs_checksum here too (with name) */
313
314 nextfh = be32_to_cpu(ri.next);
315 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
316 break;
317
318 pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
319 }
320
321 /* determine the length of the filename */
322 nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
323 if (IS_ERR_VALUE(nlen))
324 goto eio;
325
326 /* get an inode for this image position */
327 i = iget_locked(sb, pos);
328 if (!i)
329 return ERR_PTR(-ENOMEM);
330
331 if (!(i->i_state & I_NEW))
332 return i;
333
334 /* precalculate the data offset */
335 inode = ROMFS_I(i);
336 inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
337 inode->i_dataoffset = pos + inode->i_metasize;
338
bfe86848 339 set_nlink(i, 1); /* Hard to decide.. */
da4458bd
DH
340 i->i_size = be32_to_cpu(ri.size);
341 i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
342 i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
343
344 /* set up mode and ops */
345 mode = romfs_modemap[nextfh & ROMFH_TYPE];
346
347 switch (nextfh & ROMFH_TYPE) {
348 case ROMFH_DIR:
349 i->i_size = ROMFS_I(i)->i_metasize;
350 i->i_op = &romfs_dir_inode_operations;
351 i->i_fop = &romfs_dir_operations;
352 if (nextfh & ROMFH_EXEC)
353 mode |= S_IXUGO;
354 break;
355 case ROMFH_REG:
356 i->i_fop = &romfs_ro_fops;
357 i->i_data.a_ops = &romfs_aops;
da4458bd
DH
358 if (nextfh & ROMFH_EXEC)
359 mode |= S_IXUGO;
360 break;
361 case ROMFH_SYM:
362 i->i_op = &page_symlink_inode_operations;
21fc61c7 363 inode_nohighmem(i);
da4458bd
DH
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:
ca9e5368 383 pr_err("read error for inode 0x%lx\n", pos);
da4458bd
DH
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;
b6d53b1b 393
da4458bd
DH
394 inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
395 return inode ? &inode->vfs_inode : NULL;
396}
397
398/*
399 * return a spent inode to the slab cache
400 */
fa0d7e3d 401static void romfs_i_callback(struct rcu_head *head)
da4458bd 402{
fa0d7e3d 403 struct inode *inode = container_of(head, struct inode, i_rcu);
b6d53b1b 404
da4458bd
DH
405 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
406}
407
fa0d7e3d
NP
408static void romfs_destroy_inode(struct inode *inode)
409{
410 call_rcu(&inode->i_rcu, romfs_i_callback);
411}
412
da4458bd
DH
413/*
414 * get filesystem statistics
415 */
416static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
417{
8a59f5d2
CL
418 struct super_block *sb = dentry->d_sb;
419 u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
420
da4458bd
DH
421 buf->f_type = ROMFS_MAGIC;
422 buf->f_namelen = ROMFS_MAXFN;
423 buf->f_bsize = ROMBSIZE;
424 buf->f_bfree = buf->f_bavail = buf->f_ffree;
425 buf->f_blocks =
426 (romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
8a59f5d2
CL
427 buf->f_fsid.val[0] = (u32)id;
428 buf->f_fsid.val[1] = (u32)(id >> 32);
da4458bd
DH
429 return 0;
430}
431
432/*
433 * remounting must involve read-only
434 */
435static int romfs_remount(struct super_block *sb, int *flags, char *data)
436{
02b9984d 437 sync_filesystem(sb);
da4458bd
DH
438 *flags |= MS_RDONLY;
439 return 0;
440}
441
442static const struct super_operations romfs_super_ops = {
443 .alloc_inode = romfs_alloc_inode,
444 .destroy_inode = romfs_destroy_inode,
445 .statfs = romfs_statfs,
446 .remount_fs = romfs_remount,
447};
448
449/*
450 * checksum check on part of a romfs filesystem
451 */
452static __u32 romfs_checksum(const void *data, int size)
453{
454 const __be32 *ptr = data;
455 __u32 sum;
456
457 sum = 0;
458 size >>= 2;
459 while (size > 0) {
460 sum += be32_to_cpu(*ptr++);
461 size--;
462 }
463 return sum;
464}
465
466/*
467 * fill in the superblock
468 */
469static int romfs_fill_super(struct super_block *sb, void *data, int silent)
470{
471 struct romfs_super_block *rsb;
472 struct inode *root;
473 unsigned long pos, img_size;
474 const char *storage;
475 size_t len;
476 int ret;
477
478#ifdef CONFIG_BLOCK
479 if (!sb->s_mtd) {
480 sb_set_blocksize(sb, ROMBSIZE);
481 } else {
482 sb->s_blocksize = ROMBSIZE;
483 sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
484 }
485#endif
486
487 sb->s_maxbytes = 0xFFFFFFFF;
488 sb->s_magic = ROMFS_MAGIC;
489 sb->s_flags |= MS_RDONLY | MS_NOATIME;
490 sb->s_op = &romfs_super_ops;
491
492 /* read the image superblock and check it */
493 rsb = kmalloc(512, GFP_KERNEL);
494 if (!rsb)
495 return -ENOMEM;
496
497 sb->s_fs_info = (void *) 512;
498 ret = romfs_dev_read(sb, 0, rsb, 512);
499 if (ret < 0)
500 goto error_rsb;
501
502 img_size = be32_to_cpu(rsb->size);
503
504 if (sb->s_mtd && img_size > sb->s_mtd->size)
505 goto error_rsb_inval;
506
507 sb->s_fs_info = (void *) img_size;
508
509 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 ||
510 img_size < ROMFH_SIZE) {
511 if (!silent)
3d79d314 512 pr_warn("VFS: Can't find a romfs filesystem on dev %s.\n",
da4458bd
DH
513 sb->s_id);
514 goto error_rsb_inval;
515 }
516
517 if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
ca9e5368 518 pr_err("bad initial checksum on dev %s.\n", sb->s_id);
da4458bd
DH
519 goto error_rsb_inval;
520 }
521
522 storage = sb->s_mtd ? "MTD" : "the block layer";
523
524 len = strnlen(rsb->name, ROMFS_MAXFN);
525 if (!silent)
ca9e5368
FF
526 pr_notice("Mounting image '%*.*s' through %s\n",
527 (unsigned) len, (unsigned) len, rsb->name, storage);
da4458bd
DH
528
529 kfree(rsb);
530 rsb = NULL;
531
532 /* find the root directory */
533 pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
534
535 root = romfs_iget(sb, pos);
a21f3c2a 536 if (IS_ERR(root))
40e2c71d 537 return PTR_ERR(root);
da4458bd 538
48fde701 539 sb->s_root = d_make_root(root);
da4458bd 540 if (!sb->s_root)
40e2c71d 541 return -ENOMEM;
da4458bd
DH
542
543 return 0;
544
da4458bd
DH
545error_rsb_inval:
546 ret = -EINVAL;
547error_rsb:
7e32b7bb 548 kfree(rsb);
da4458bd
DH
549 return ret;
550}
551
552/*
553 * get a superblock for mounting
554 */
848b83a5 555static struct dentry *romfs_mount(struct file_system_type *fs_type,
da4458bd 556 int flags, const char *dev_name,
848b83a5 557 void *data)
da4458bd 558{
848b83a5 559 struct dentry *ret = ERR_PTR(-EINVAL);
da4458bd
DH
560
561#ifdef CONFIG_ROMFS_ON_MTD
848b83a5 562 ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super);
da4458bd
DH
563#endif
564#ifdef CONFIG_ROMFS_ON_BLOCK
848b83a5
AV
565 if (ret == ERR_PTR(-EINVAL))
566 ret = mount_bdev(fs_type, flags, dev_name, data,
567 romfs_fill_super);
da4458bd
DH
568#endif
569 return ret;
570}
571
572/*
573 * destroy a romfs superblock in the appropriate manner
574 */
575static void romfs_kill_sb(struct super_block *sb)
576{
577#ifdef CONFIG_ROMFS_ON_MTD
578 if (sb->s_mtd) {
579 kill_mtd_super(sb);
580 return;
581 }
582#endif
583#ifdef CONFIG_ROMFS_ON_BLOCK
584 if (sb->s_bdev) {
585 kill_block_super(sb);
586 return;
587 }
588#endif
589}
590
591static struct file_system_type romfs_fs_type = {
592 .owner = THIS_MODULE,
593 .name = "romfs",
848b83a5 594 .mount = romfs_mount,
da4458bd
DH
595 .kill_sb = romfs_kill_sb,
596 .fs_flags = FS_REQUIRES_DEV,
597};
7f78e035 598MODULE_ALIAS_FS("romfs");
da4458bd
DH
599
600/*
601 * inode storage initialiser
602 */
603static void romfs_i_init_once(void *_inode)
604{
605 struct romfs_inode_info *inode = _inode;
606
607 inode_init_once(&inode->vfs_inode);
608}
609
610/*
611 * romfs module initialisation
612 */
613static int __init init_romfs_fs(void)
614{
615 int ret;
616
3d79d314 617 pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");
da4458bd
DH
618
619 romfs_inode_cachep =
620 kmem_cache_create("romfs_i",
621 sizeof(struct romfs_inode_info), 0,
5d097056
VD
622 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD |
623 SLAB_ACCOUNT, romfs_i_init_once);
da4458bd
DH
624
625 if (!romfs_inode_cachep) {
ca9e5368 626 pr_err("Failed to initialise inode cache\n");
da4458bd
DH
627 return -ENOMEM;
628 }
629 ret = register_filesystem(&romfs_fs_type);
630 if (ret) {
ca9e5368 631 pr_err("Failed to register filesystem\n");
da4458bd
DH
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 */