1
/* Block- or MTD-based romfs
3
* Copyright Ā© 2007 Red Hat, Inc. All Rights Reserved.
4
* Written by David Howells (dhowells@redhat.com)
6
* Derived from: ROMFS file system, Linux implementation
8
* Copyright Ā© 1997-1999 Janos Farkas <chexum@shadow.banki.hu>
10
* Using parts of the minix filesystem
11
* Copyright Ā© 1991, 1992 Linus Torvalds
13
* and parts of the affs filesystem additionally
14
* Copyright Ā© 1993 Ray Burr
15
* Copyright Ā© 1996 Hans-Joachim Widmaier
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
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
42
* clean up page flags setting
43
* (error, uptodate, locking) in
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
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.
59
#include <linux/module.h>
60
#include <linux/string.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>
77
static struct kmem_cache *romfs_inode_cachep;
79
static const umode_t romfs_modemap[8] = {
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 */
90
static const unsigned char romfs_dtype_table[] = {
91
DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
94
static struct inode *romfs_iget(struct super_block *sb, unsigned long pos);
97
* read a page worth of data from the image
99
static int romfs_readpage(struct file *file, struct page *page)
101
struct inode *inode = page->mapping->host;
103
unsigned long fillsize, pos;
111
/* 32 bit warning -- but not for us :) */
112
offset = page_offset(page);
113
size = i_size_read(inode);
118
fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;
120
pos = ROMFS_I(inode)->i_dataoffset + offset;
122
ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
130
if (fillsize < PAGE_SIZE)
131
memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
133
SetPageUptodate(page);
135
flush_dcache_page(page);
141
static const struct address_space_operations romfs_aops = {
142
.readpage = romfs_readpage
146
* read the entries from a directory
148
static int romfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
150
struct inode *i = filp->f_dentry->d_inode;
151
struct romfs_inode ri;
152
unsigned long offset, maxoff;
155
char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
158
maxoff = romfs_maxsize(i->i_sb);
160
offset = filp->f_pos;
162
offset = i->i_ino & ROMFH_MASK;
163
ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
166
offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
169
/* Not really failsafe, but we are read-only... */
171
if (!offset || offset >= maxoff) {
173
filp->f_pos = offset;
176
filp->f_pos = offset;
178
/* Fetch inode info */
179
ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
183
j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
188
ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
194
nextfh = be32_to_cpu(ri.next);
195
if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
196
ino = be32_to_cpu(ri.spec);
197
if (filldir(dirent, fsname, j, offset, ino,
198
romfs_dtype_table[nextfh & ROMFH_TYPE]) < 0)
202
offset = nextfh & ROMFH_MASK;
210
* look up an entry in a directory
212
static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry,
213
struct nameidata *nd)
215
unsigned long offset, maxoff;
217
struct romfs_inode ri;
218
const char *name; /* got from dentry */
221
offset = dir->i_ino & ROMFH_MASK;
222
ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
226
/* search all the file entries in the list starting from the one
227
* pointed to by the directory's special data */
228
maxoff = romfs_maxsize(dir->i_sb);
229
offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
231
name = dentry->d_name.name;
232
len = dentry->d_name.len;
235
if (!offset || offset >= maxoff)
238
ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
242
/* try to match the first 16 bytes of name */
243
ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
251
offset = be32_to_cpu(ri.next) & ROMFH_MASK;
254
/* Hard link handling */
255
if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
256
offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
258
inode = romfs_iget(dir->i_sb, offset);
260
ret = PTR_ERR(inode);
266
* it's a bit funky, _lookup needs to return an error code
267
* (negative) or a NULL, both as a dentry. ENOENT should not
268
* be returned, instead we need to create a negative dentry by
269
* d_add(dentry, NULL); and return 0 as no error.
270
* (Although as I see, it only matters on writable file
276
d_add(dentry, inode);
282
static const struct file_operations romfs_dir_operations = {
283
.read = generic_read_dir,
284
.readdir = romfs_readdir,
285
.llseek = default_llseek,
288
static const struct inode_operations romfs_dir_inode_operations = {
289
.lookup = romfs_lookup,
293
* get a romfs inode based on its position in the image (which doubles as the
296
static struct inode *romfs_iget(struct super_block *sb, unsigned long pos)
298
struct romfs_inode_info *inode;
299
struct romfs_inode ri;
306
/* we might have to traverse a chain of "hard link" file entries to get
307
* to the actual file */
309
ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
313
/* XXX: do romfs_checksum here too (with name) */
315
nextfh = be32_to_cpu(ri.next);
316
if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
319
pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
322
/* determine the length of the filename */
323
nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
324
if (IS_ERR_VALUE(nlen))
327
/* get an inode for this image position */
328
i = iget_locked(sb, pos);
330
return ERR_PTR(-ENOMEM);
332
if (!(i->i_state & I_NEW))
335
/* precalculate the data offset */
337
inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
338
inode->i_dataoffset = pos + inode->i_metasize;
340
set_nlink(i, 1); /* Hard to decide.. */
341
i->i_size = be32_to_cpu(ri.size);
342
i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
343
i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
345
/* set up mode and ops */
346
mode = romfs_modemap[nextfh & ROMFH_TYPE];
348
switch (nextfh & ROMFH_TYPE) {
350
i->i_size = ROMFS_I(i)->i_metasize;
351
i->i_op = &romfs_dir_inode_operations;
352
i->i_fop = &romfs_dir_operations;
353
if (nextfh & ROMFH_EXEC)
357
i->i_fop = &romfs_ro_fops;
358
i->i_data.a_ops = &romfs_aops;
360
i->i_data.backing_dev_info =
361
i->i_sb->s_mtd->backing_dev_info;
362
if (nextfh & ROMFH_EXEC)
366
i->i_op = &page_symlink_inode_operations;
367
i->i_data.a_ops = &romfs_aops;
371
/* depending on MBZ for sock/fifos */
372
nextfh = be32_to_cpu(ri.spec);
373
init_special_inode(i, mode, MKDEV(nextfh >> 16,
386
printk(KERN_ERR "ROMFS: read error for inode 0x%lx\n", pos);
391
* allocate a new inode
393
static struct inode *romfs_alloc_inode(struct super_block *sb)
395
struct romfs_inode_info *inode;
396
inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
397
return inode ? &inode->vfs_inode : NULL;
401
* return a spent inode to the slab cache
403
static void romfs_i_callback(struct rcu_head *head)
405
struct inode *inode = container_of(head, struct inode, i_rcu);
406
INIT_LIST_HEAD(&inode->i_dentry);
407
kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
410
static void romfs_destroy_inode(struct inode *inode)
412
call_rcu(&inode->i_rcu, romfs_i_callback);
416
* get filesystem statistics
418
static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
420
struct super_block *sb = dentry->d_sb;
421
u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
423
buf->f_type = ROMFS_MAGIC;
424
buf->f_namelen = ROMFS_MAXFN;
425
buf->f_bsize = ROMBSIZE;
426
buf->f_bfree = buf->f_bavail = buf->f_ffree;
428
(romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
429
buf->f_fsid.val[0] = (u32)id;
430
buf->f_fsid.val[1] = (u32)(id >> 32);
435
* remounting must involve read-only
437
static int romfs_remount(struct super_block *sb, int *flags, char *data)
443
static const struct super_operations romfs_super_ops = {
444
.alloc_inode = romfs_alloc_inode,
445
.destroy_inode = romfs_destroy_inode,
446
.statfs = romfs_statfs,
447
.remount_fs = romfs_remount,
451
* checksum check on part of a romfs filesystem
453
static __u32 romfs_checksum(const void *data, int size)
455
const __be32 *ptr = data;
461
sum += be32_to_cpu(*ptr++);
468
* fill in the superblock
470
static int romfs_fill_super(struct super_block *sb, void *data, int silent)
472
struct romfs_super_block *rsb;
474
unsigned long pos, img_size;
481
sb_set_blocksize(sb, ROMBSIZE);
483
sb->s_blocksize = ROMBSIZE;
484
sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
488
sb->s_maxbytes = 0xFFFFFFFF;
489
sb->s_magic = ROMFS_MAGIC;
490
sb->s_flags |= MS_RDONLY | MS_NOATIME;
491
sb->s_op = &romfs_super_ops;
493
/* read the image superblock and check it */
494
rsb = kmalloc(512, GFP_KERNEL);
498
sb->s_fs_info = (void *) 512;
499
ret = romfs_dev_read(sb, 0, rsb, 512);
503
img_size = be32_to_cpu(rsb->size);
505
if (sb->s_mtd && img_size > sb->s_mtd->size)
506
goto error_rsb_inval;
508
sb->s_fs_info = (void *) img_size;
510
if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 ||
511
img_size < ROMFH_SIZE) {
513
printk(KERN_WARNING "VFS:"
514
" Can't find a romfs filesystem on dev %s.\n",
516
goto error_rsb_inval;
519
if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
520
printk(KERN_ERR "ROMFS: bad initial checksum on dev %s.\n",
522
goto error_rsb_inval;
525
storage = sb->s_mtd ? "MTD" : "the block layer";
527
len = strnlen(rsb->name, ROMFS_MAXFN);
529
printk(KERN_NOTICE "ROMFS: Mounting image '%*.*s' through %s\n",
530
(unsigned) len, (unsigned) len, rsb->name, storage);
535
/* find the root directory */
536
pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
538
root = romfs_iget(sb, pos);
542
sb->s_root = d_alloc_root(root);
560
* get a superblock for mounting
562
static struct dentry *romfs_mount(struct file_system_type *fs_type,
563
int flags, const char *dev_name,
566
struct dentry *ret = ERR_PTR(-EINVAL);
568
#ifdef CONFIG_ROMFS_ON_MTD
569
ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super);
571
#ifdef CONFIG_ROMFS_ON_BLOCK
572
if (ret == ERR_PTR(-EINVAL))
573
ret = mount_bdev(fs_type, flags, dev_name, data,
580
* destroy a romfs superblock in the appropriate manner
582
static void romfs_kill_sb(struct super_block *sb)
584
#ifdef CONFIG_ROMFS_ON_MTD
590
#ifdef CONFIG_ROMFS_ON_BLOCK
592
kill_block_super(sb);
598
static struct file_system_type romfs_fs_type = {
599
.owner = THIS_MODULE,
601
.mount = romfs_mount,
602
.kill_sb = romfs_kill_sb,
603
.fs_flags = FS_REQUIRES_DEV,
607
* inode storage initialiser
609
static void romfs_i_init_once(void *_inode)
611
struct romfs_inode_info *inode = _inode;
613
inode_init_once(&inode->vfs_inode);
617
* romfs module initialisation
619
static int __init init_romfs_fs(void)
623
printk(KERN_INFO "ROMFS MTD (C) 2007 Red Hat, Inc.\n");
626
kmem_cache_create("romfs_i",
627
sizeof(struct romfs_inode_info), 0,
628
SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
631
if (!romfs_inode_cachep) {
633
"ROMFS error: Failed to initialise inode cache\n");
636
ret = register_filesystem(&romfs_fs_type);
638
printk(KERN_ERR "ROMFS error: Failed to register filesystem\n");
644
kmem_cache_destroy(romfs_inode_cachep);
649
* romfs module removal
651
static void __exit exit_romfs_fs(void)
653
unregister_filesystem(&romfs_fs_type);
654
kmem_cache_destroy(romfs_inode_cachep);
657
module_init(init_romfs_fs);
658
module_exit(exit_romfs_fs);
660
MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
661
MODULE_AUTHOR("Red Hat, Inc.");
662
MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */