1 /* Block- or MTD-based romfs
3 * Copyright © 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 © 1997-1999 Janos Farkas <chexum@shadow.banki.hu>
10 * Using parts of the minix filesystem
11 * Copyright © 1991, 1992 Linus Torvalds
13 * and parts of the affs filesystem additionally
14 * Copyright © 1993 Ray Burr
15 * Copyright © 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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
61 #include <linux/module.h>
62 #include <linux/string.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 <linux/major.h>
80 static struct kmem_cache
*romfs_inode_cachep
;
82 static const umode_t romfs_modemap
[8] = {
84 S_IFDIR
| 0644, /* directory */
85 S_IFREG
| 0644, /* regular file */
86 S_IFLNK
| 0777, /* symlink */
87 S_IFBLK
| 0600, /* blockdev */
88 S_IFCHR
| 0600, /* chardev */
89 S_IFSOCK
| 0644, /* socket */
90 S_IFIFO
| 0644 /* FIFO */
93 static const unsigned char romfs_dtype_table
[] = {
94 DT_UNKNOWN
, DT_DIR
, DT_REG
, DT_LNK
, DT_BLK
, DT_CHR
, DT_SOCK
, DT_FIFO
97 static struct inode
*romfs_iget(struct super_block
*sb
, unsigned long pos
);
100 * read a page worth of data from the image
102 static int romfs_readpage(struct file
*file
, struct page
*page
)
104 struct inode
*inode
= page
->mapping
->host
;
106 unsigned long fillsize
, pos
;
114 /* 32 bit warning -- but not for us :) */
115 offset
= page_offset(page
);
116 size
= i_size_read(inode
);
121 fillsize
= size
> PAGE_SIZE
? PAGE_SIZE
: size
;
123 pos
= ROMFS_I(inode
)->i_dataoffset
+ offset
;
125 ret
= romfs_dev_read(inode
->i_sb
, pos
, buf
, fillsize
);
133 if (fillsize
< PAGE_SIZE
)
134 memset(buf
+ fillsize
, 0, PAGE_SIZE
- fillsize
);
136 SetPageUptodate(page
);
138 flush_dcache_page(page
);
144 static const struct address_space_operations romfs_aops
= {
145 .readpage
= romfs_readpage
149 * read the entries from a directory
151 static int romfs_readdir(struct file
*file
, struct dir_context
*ctx
)
153 struct inode
*i
= file_inode(file
);
154 struct romfs_inode ri
;
155 unsigned long offset
, maxoff
;
157 char fsname
[ROMFS_MAXFN
]; /* XXX dynamic? */
160 maxoff
= romfs_maxsize(i
->i_sb
);
164 offset
= i
->i_ino
& ROMFH_MASK
;
165 ret
= romfs_dev_read(i
->i_sb
, offset
, &ri
, ROMFH_SIZE
);
168 offset
= be32_to_cpu(ri
.spec
) & ROMFH_MASK
;
171 /* Not really failsafe, but we are read-only... */
173 if (!offset
|| offset
>= maxoff
) {
180 /* Fetch inode info */
181 ret
= romfs_dev_read(i
->i_sb
, offset
, &ri
, ROMFH_SIZE
);
185 j
= romfs_dev_strnlen(i
->i_sb
, offset
+ ROMFH_SIZE
,
190 ret
= romfs_dev_read(i
->i_sb
, offset
+ ROMFH_SIZE
, fsname
, j
);
196 nextfh
= be32_to_cpu(ri
.next
);
197 if ((nextfh
& ROMFH_TYPE
) == ROMFH_HRD
)
198 ino
= be32_to_cpu(ri
.spec
);
199 if (!dir_emit(ctx
, fsname
, j
, ino
,
200 romfs_dtype_table
[nextfh
& ROMFH_TYPE
]))
203 offset
= nextfh
& ROMFH_MASK
;
210 * look up an entry in a directory
212 static struct dentry
*romfs_lookup(struct inode
*dir
, struct dentry
*dentry
,
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 .iterate
= 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
;
359 if (nextfh
& ROMFH_EXEC
)
363 i
->i_op
= &page_symlink_inode_operations
;
364 i
->i_data
.a_ops
= &romfs_aops
;
368 /* depending on MBZ for sock/fifos */
369 nextfh
= be32_to_cpu(ri
.spec
);
370 init_special_inode(i
, mode
, MKDEV(nextfh
>> 16,
383 pr_err("read error for inode 0x%lx\n", pos
);
388 * allocate a new inode
390 static struct inode
*romfs_alloc_inode(struct super_block
*sb
)
392 struct romfs_inode_info
*inode
;
394 inode
= kmem_cache_alloc(romfs_inode_cachep
, GFP_KERNEL
);
395 return inode
? &inode
->vfs_inode
: NULL
;
399 * return a spent inode to the slab cache
401 static void romfs_i_callback(struct rcu_head
*head
)
403 struct inode
*inode
= container_of(head
, struct inode
, i_rcu
);
405 kmem_cache_free(romfs_inode_cachep
, ROMFS_I(inode
));
408 static void romfs_destroy_inode(struct inode
*inode
)
410 call_rcu(&inode
->i_rcu
, romfs_i_callback
);
414 * get filesystem statistics
416 static int romfs_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
418 struct super_block
*sb
= dentry
->d_sb
;
421 /* When calling huge_encode_dev(),
422 * use sb->s_bdev->bd_dev when,
423 * - CONFIG_ROMFS_ON_BLOCK defined
424 * use sb->s_dev when,
425 * - CONFIG_ROMFS_ON_BLOCK undefined and
426 * - CONFIG_ROMFS_ON_MTD defined
427 * leave id as 0 when,
428 * - CONFIG_ROMFS_ON_BLOCK undefined and
429 * - CONFIG_ROMFS_ON_MTD undefined
432 id
= huge_encode_dev(sb
->s_bdev
->bd_dev
);
434 id
= huge_encode_dev(sb
->s_dev
);
436 buf
->f_type
= ROMFS_MAGIC
;
437 buf
->f_namelen
= ROMFS_MAXFN
;
438 buf
->f_bsize
= ROMBSIZE
;
439 buf
->f_bfree
= buf
->f_bavail
= buf
->f_ffree
;
441 (romfs_maxsize(dentry
->d_sb
) + ROMBSIZE
- 1) >> ROMBSBITS
;
442 buf
->f_fsid
.val
[0] = (u32
)id
;
443 buf
->f_fsid
.val
[1] = (u32
)(id
>> 32);
448 * remounting must involve read-only
450 static int romfs_remount(struct super_block
*sb
, int *flags
, char *data
)
457 static const struct super_operations romfs_super_ops
= {
458 .alloc_inode
= romfs_alloc_inode
,
459 .destroy_inode
= romfs_destroy_inode
,
460 .statfs
= romfs_statfs
,
461 .remount_fs
= romfs_remount
,
465 * checksum check on part of a romfs filesystem
467 static __u32
romfs_checksum(const void *data
, int size
)
469 const __be32
*ptr
= data
;
475 sum
+= be32_to_cpu(*ptr
++);
482 * fill in the superblock
484 static int romfs_fill_super(struct super_block
*sb
, void *data
, int silent
)
486 struct romfs_super_block
*rsb
;
488 unsigned long pos
, img_size
;
495 sb_set_blocksize(sb
, ROMBSIZE
);
497 sb
->s_blocksize
= ROMBSIZE
;
498 sb
->s_blocksize_bits
= blksize_bits(ROMBSIZE
);
502 sb
->s_maxbytes
= 0xFFFFFFFF;
503 sb
->s_magic
= ROMFS_MAGIC
;
504 sb
->s_flags
|= MS_RDONLY
| MS_NOATIME
;
505 sb
->s_op
= &romfs_super_ops
;
507 #ifdef CONFIG_ROMFS_ON_MTD
508 /* Use same dev ID from the underlying mtdblock device */
510 sb
->s_dev
= MKDEV(MTD_BLOCK_MAJOR
, sb
->s_mtd
->index
);
512 /* read the image superblock and check it */
513 rsb
= kmalloc(512, GFP_KERNEL
);
517 sb
->s_fs_info
= (void *) 512;
518 ret
= romfs_dev_read(sb
, 0, rsb
, 512);
522 img_size
= be32_to_cpu(rsb
->size
);
524 if (sb
->s_mtd
&& img_size
> sb
->s_mtd
->size
)
525 goto error_rsb_inval
;
527 sb
->s_fs_info
= (void *) img_size
;
529 if (rsb
->word0
!= ROMSB_WORD0
|| rsb
->word1
!= ROMSB_WORD1
||
530 img_size
< ROMFH_SIZE
) {
532 pr_warn("VFS: Can't find a romfs filesystem on dev %s.\n",
534 goto error_rsb_inval
;
537 if (romfs_checksum(rsb
, min_t(size_t, img_size
, 512))) {
538 pr_err("bad initial checksum on dev %s.\n", sb
->s_id
);
539 goto error_rsb_inval
;
542 storage
= sb
->s_mtd
? "MTD" : "the block layer";
544 len
= strnlen(rsb
->name
, ROMFS_MAXFN
);
546 pr_notice("Mounting image '%*.*s' through %s\n",
547 (unsigned) len
, (unsigned) len
, rsb
->name
, storage
);
552 /* find the root directory */
553 pos
= (ROMFH_SIZE
+ len
+ 1 + ROMFH_PAD
) & ROMFH_MASK
;
555 root
= romfs_iget(sb
, pos
);
557 return PTR_ERR(root
);
559 sb
->s_root
= d_make_root(root
);
573 * get a superblock for mounting
575 static struct dentry
*romfs_mount(struct file_system_type
*fs_type
,
576 int flags
, const char *dev_name
,
579 struct dentry
*ret
= ERR_PTR(-EINVAL
);
581 #ifdef CONFIG_ROMFS_ON_MTD
582 ret
= mount_mtd(fs_type
, flags
, dev_name
, data
, romfs_fill_super
);
584 #ifdef CONFIG_ROMFS_ON_BLOCK
585 if (ret
== ERR_PTR(-EINVAL
))
586 ret
= mount_bdev(fs_type
, flags
, dev_name
, data
,
593 * destroy a romfs superblock in the appropriate manner
595 static void romfs_kill_sb(struct super_block
*sb
)
597 #ifdef CONFIG_ROMFS_ON_MTD
603 #ifdef CONFIG_ROMFS_ON_BLOCK
605 kill_block_super(sb
);
611 static struct file_system_type romfs_fs_type
= {
612 .owner
= THIS_MODULE
,
614 .mount
= romfs_mount
,
615 .kill_sb
= romfs_kill_sb
,
616 .fs_flags
= FS_REQUIRES_DEV
,
618 MODULE_ALIAS_FS("romfs");
621 * inode storage initialiser
623 static void romfs_i_init_once(void *_inode
)
625 struct romfs_inode_info
*inode
= _inode
;
627 inode_init_once(&inode
->vfs_inode
);
631 * romfs module initialisation
633 static int __init
init_romfs_fs(void)
637 pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");
640 kmem_cache_create("romfs_i",
641 sizeof(struct romfs_inode_info
), 0,
642 SLAB_RECLAIM_ACCOUNT
| SLAB_MEM_SPREAD
,
645 if (!romfs_inode_cachep
) {
646 pr_err("Failed to initialise inode cache\n");
649 ret
= register_filesystem(&romfs_fs_type
);
651 pr_err("Failed to register filesystem\n");
657 kmem_cache_destroy(romfs_inode_cachep
);
662 * romfs module removal
664 static void __exit
exit_romfs_fs(void)
666 unregister_filesystem(&romfs_fs_type
);
668 * Make sure all delayed rcu free inodes are flushed before we
672 kmem_cache_destroy(romfs_inode_cachep
);
675 module_init(init_romfs_fs
);
676 module_exit(exit_romfs_fs
);
678 MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
679 MODULE_AUTHOR("Red Hat, Inc.");
680 MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */