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CommitLineData
1da177e4
LT
1/*
2 * Compressed rom filesystem for Linux.
3 *
4 * Copyright (C) 1999 Linus Torvalds.
5 *
6 * This file is released under the GPL.
7 */
8
9/*
10 * These are the VFS interfaces to the compressed rom filesystem.
11 * The actual compression is based on zlib, see the other files.
12 */
13
14#include <linux/module.h>
15#include <linux/fs.h>
16#include <linux/pagemap.h>
17#include <linux/init.h>
18#include <linux/string.h>
19#include <linux/blkdev.h>
20#include <linux/cramfs_fs.h>
21#include <linux/slab.h>
22#include <linux/cramfs_fs_sb.h>
23#include <linux/buffer_head.h>
24#include <linux/vfs.h>
353ab6e9 25#include <linux/mutex.h>
1da177e4
LT
26#include <asm/semaphore.h>
27
28#include <asm/uaccess.h>
29
ee9b6d61 30static const struct super_operations cramfs_ops;
754661f1 31static const struct inode_operations cramfs_dir_inode_operations;
4b6f5d20 32static const struct file_operations cramfs_directory_operations;
f5e54d6e 33static const struct address_space_operations cramfs_aops;
1da177e4 34
353ab6e9 35static DEFINE_MUTEX(read_mutex);
1da177e4
LT
36
37
38/* These two macros may change in future, to provide better st_ino
39 semantics. */
ff3aea0e 40#define CRAMINO(x) (((x)->offset && (x)->size)?(x)->offset<<2:1)
1da177e4
LT
41#define OFFSET(x) ((x)->i_ino)
42
a97c9bf3
DJ
43
44static int cramfs_iget5_test(struct inode *inode, void *opaque)
45{
46 struct cramfs_inode *cramfs_inode = opaque;
47
48 if (inode->i_ino != CRAMINO(cramfs_inode))
49 return 0; /* does not match */
50
51 if (inode->i_ino != 1)
52 return 1;
53
54 /* all empty directories, char, block, pipe, and sock, share inode #1 */
55
56 if ((inode->i_mode != cramfs_inode->mode) ||
57 (inode->i_gid != cramfs_inode->gid) ||
58 (inode->i_uid != cramfs_inode->uid))
59 return 0; /* does not match */
60
61 if ((S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) &&
62 (inode->i_rdev != old_decode_dev(cramfs_inode->size)))
63 return 0; /* does not match */
64
65 return 1; /* matches */
66}
67
68static int cramfs_iget5_set(struct inode *inode, void *opaque)
69{
ff3aea0e 70 static struct timespec zerotime;
a97c9bf3 71 struct cramfs_inode *cramfs_inode = opaque;
ff3aea0e
DJ
72 inode->i_mode = cramfs_inode->mode;
73 inode->i_uid = cramfs_inode->uid;
74 inode->i_size = cramfs_inode->size;
75 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
ff3aea0e
DJ
76 inode->i_gid = cramfs_inode->gid;
77 /* Struct copy intentional */
78 inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
a97c9bf3 79 inode->i_ino = CRAMINO(cramfs_inode);
ff3aea0e
DJ
80 /* inode->i_nlink is left 1 - arguably wrong for directories,
81 but it's the best we can do without reading the directory
82 contents. 1 yields the right result in GNU find, even
83 without -noleaf option. */
84 if (S_ISREG(inode->i_mode)) {
85 inode->i_fop = &generic_ro_fops;
86 inode->i_data.a_ops = &cramfs_aops;
87 } else if (S_ISDIR(inode->i_mode)) {
88 inode->i_op = &cramfs_dir_inode_operations;
89 inode->i_fop = &cramfs_directory_operations;
90 } else if (S_ISLNK(inode->i_mode)) {
91 inode->i_op = &page_symlink_inode_operations;
92 inode->i_data.a_ops = &cramfs_aops;
93 } else {
94 inode->i_size = 0;
95 inode->i_blocks = 0;
96 init_special_inode(inode, inode->i_mode,
97 old_decode_dev(cramfs_inode->size));
98 }
a97c9bf3
DJ
99 return 0;
100}
101
102static struct inode *get_cramfs_inode(struct super_block *sb,
103 struct cramfs_inode * cramfs_inode)
1da177e4 104{
a97c9bf3
DJ
105 struct inode *inode = iget5_locked(sb, CRAMINO(cramfs_inode),
106 cramfs_iget5_test, cramfs_iget5_set,
107 cramfs_inode);
a97c9bf3 108 if (inode && (inode->i_state & I_NEW)) {
a97c9bf3 109 unlock_new_inode(inode);
1da177e4
LT
110 }
111 return inode;
112}
113
114/*
115 * We have our own block cache: don't fill up the buffer cache
116 * with the rom-image, because the way the filesystem is set
117 * up the accesses should be fairly regular and cached in the
118 * page cache and dentry tree anyway..
119 *
120 * This also acts as a way to guarantee contiguous areas of up to
121 * BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
122 * worry about end-of-buffer issues even when decompressing a full
123 * page cache.
124 */
125#define READ_BUFFERS (2)
126/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
127#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
128
129/*
130 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
131 * data that takes up more space than the original and with unlucky
132 * alignment.
133 */
134#define BLKS_PER_BUF_SHIFT (2)
135#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
136#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
137
138static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
139static unsigned buffer_blocknr[READ_BUFFERS];
140static struct super_block * buffer_dev[READ_BUFFERS];
141static int next_buffer;
142
143/*
144 * Returns a pointer to a buffer containing at least LEN bytes of
145 * filesystem starting at byte offset OFFSET into the filesystem.
146 */
147static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
148{
149 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
150 struct page *pages[BLKS_PER_BUF];
6bbfb077 151 unsigned i, blocknr, buffer;
1da177e4
LT
152 unsigned long devsize;
153 char *data;
154
155 if (!len)
156 return NULL;
157 blocknr = offset >> PAGE_CACHE_SHIFT;
158 offset &= PAGE_CACHE_SIZE - 1;
159
160 /* Check if an existing buffer already has the data.. */
161 for (i = 0; i < READ_BUFFERS; i++) {
162 unsigned int blk_offset;
163
164 if (buffer_dev[i] != sb)
165 continue;
166 if (blocknr < buffer_blocknr[i])
167 continue;
168 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
169 blk_offset += offset;
170 if (blk_offset + len > BUFFER_SIZE)
171 continue;
172 return read_buffers[i] + blk_offset;
173 }
174
175 devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
176
177 /* Ok, read in BLKS_PER_BUF pages completely first. */
1da177e4
LT
178 for (i = 0; i < BLKS_PER_BUF; i++) {
179 struct page *page = NULL;
180
181 if (blocknr + i < devsize) {
6fe6900e
NP
182 page = read_mapping_page_async(mapping, blocknr + i,
183 NULL);
1da177e4
LT
184 /* synchronous error? */
185 if (IS_ERR(page))
186 page = NULL;
187 }
188 pages[i] = page;
189 }
190
191 for (i = 0; i < BLKS_PER_BUF; i++) {
192 struct page *page = pages[i];
193 if (page) {
194 wait_on_page_locked(page);
195 if (!PageUptodate(page)) {
196 /* asynchronous error */
197 page_cache_release(page);
198 pages[i] = NULL;
199 }
200 }
201 }
202
203 buffer = next_buffer;
204 next_buffer = NEXT_BUFFER(buffer);
205 buffer_blocknr[buffer] = blocknr;
206 buffer_dev[buffer] = sb;
207
208 data = read_buffers[buffer];
209 for (i = 0; i < BLKS_PER_BUF; i++) {
210 struct page *page = pages[i];
211 if (page) {
212 memcpy(data, kmap(page), PAGE_CACHE_SIZE);
213 kunmap(page);
214 page_cache_release(page);
215 } else
216 memset(data, 0, PAGE_CACHE_SIZE);
217 data += PAGE_CACHE_SIZE;
218 }
219 return read_buffers[buffer] + offset;
220}
221
222static void cramfs_put_super(struct super_block *sb)
223{
224 kfree(sb->s_fs_info);
225 sb->s_fs_info = NULL;
226}
227
228static int cramfs_remount(struct super_block *sb, int *flags, char *data)
229{
230 *flags |= MS_RDONLY;
231 return 0;
232}
233
234static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
235{
236 int i;
237 struct cramfs_super super;
238 unsigned long root_offset;
239 struct cramfs_sb_info *sbi;
240 struct inode *root;
241
242 sb->s_flags |= MS_RDONLY;
243
f8314dc6 244 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
1da177e4
LT
245 if (!sbi)
246 return -ENOMEM;
247 sb->s_fs_info = sbi;
1da177e4
LT
248
249 /* Invalidate the read buffers on mount: think disk change.. */
353ab6e9 250 mutex_lock(&read_mutex);
1da177e4
LT
251 for (i = 0; i < READ_BUFFERS; i++)
252 buffer_blocknr[i] = -1;
253
254 /* Read the first block and get the superblock from it */
255 memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
353ab6e9 256 mutex_unlock(&read_mutex);
1da177e4
LT
257
258 /* Do sanity checks on the superblock */
259 if (super.magic != CRAMFS_MAGIC) {
ac8d35c5
AD
260 /* check for wrong endianess */
261 if (super.magic == CRAMFS_MAGIC_WEND) {
262 if (!silent)
263 printk(KERN_ERR "cramfs: wrong endianess\n");
264 goto out;
265 }
266
1da177e4 267 /* check at 512 byte offset */
353ab6e9 268 mutex_lock(&read_mutex);
1da177e4 269 memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
353ab6e9 270 mutex_unlock(&read_mutex);
1da177e4 271 if (super.magic != CRAMFS_MAGIC) {
ac8d35c5
AD
272 if (super.magic == CRAMFS_MAGIC_WEND && !silent)
273 printk(KERN_ERR "cramfs: wrong endianess\n");
274 else if (!silent)
1da177e4
LT
275 printk(KERN_ERR "cramfs: wrong magic\n");
276 goto out;
277 }
278 }
279
280 /* get feature flags first */
281 if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
282 printk(KERN_ERR "cramfs: unsupported filesystem features\n");
283 goto out;
284 }
285
286 /* Check that the root inode is in a sane state */
287 if (!S_ISDIR(super.root.mode)) {
288 printk(KERN_ERR "cramfs: root is not a directory\n");
289 goto out;
290 }
291 root_offset = super.root.offset << 2;
292 if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
293 sbi->size=super.size;
294 sbi->blocks=super.fsid.blocks;
295 sbi->files=super.fsid.files;
296 } else {
297 sbi->size=1<<28;
298 sbi->blocks=0;
299 sbi->files=0;
300 }
301 sbi->magic=super.magic;
302 sbi->flags=super.flags;
303 if (root_offset == 0)
304 printk(KERN_INFO "cramfs: empty filesystem");
305 else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
306 ((root_offset != sizeof(struct cramfs_super)) &&
307 (root_offset != 512 + sizeof(struct cramfs_super))))
308 {
309 printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
310 goto out;
311 }
312
313 /* Set it all up.. */
314 sb->s_op = &cramfs_ops;
315 root = get_cramfs_inode(sb, &super.root);
316 if (!root)
317 goto out;
318 sb->s_root = d_alloc_root(root);
319 if (!sb->s_root) {
320 iput(root);
321 goto out;
322 }
323 return 0;
324out:
325 kfree(sbi);
326 sb->s_fs_info = NULL;
327 return -EINVAL;
328}
329
726c3342 330static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1da177e4 331{
726c3342
DH
332 struct super_block *sb = dentry->d_sb;
333
1da177e4
LT
334 buf->f_type = CRAMFS_MAGIC;
335 buf->f_bsize = PAGE_CACHE_SIZE;
336 buf->f_blocks = CRAMFS_SB(sb)->blocks;
337 buf->f_bfree = 0;
338 buf->f_bavail = 0;
339 buf->f_files = CRAMFS_SB(sb)->files;
340 buf->f_ffree = 0;
341 buf->f_namelen = CRAMFS_MAXPATHLEN;
342 return 0;
343}
344
345/*
346 * Read a cramfs directory entry.
347 */
348static int cramfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
349{
352d8af7 350 struct inode *inode = filp->f_path.dentry->d_inode;
1da177e4
LT
351 struct super_block *sb = inode->i_sb;
352 char *buf;
353 unsigned int offset;
354 int copied;
355
356 /* Offset within the thing. */
357 offset = filp->f_pos;
358 if (offset >= inode->i_size)
359 return 0;
360 /* Directory entries are always 4-byte aligned */
361 if (offset & 3)
362 return -EINVAL;
363
364 buf = kmalloc(256, GFP_KERNEL);
365 if (!buf)
366 return -ENOMEM;
367
368 copied = 0;
369 while (offset < inode->i_size) {
370 struct cramfs_inode *de;
371 unsigned long nextoffset;
372 char *name;
373 ino_t ino;
374 mode_t mode;
375 int namelen, error;
376
353ab6e9 377 mutex_lock(&read_mutex);
1da177e4
LT
378 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+256);
379 name = (char *)(de+1);
380
381 /*
382 * Namelengths on disk are shifted by two
383 * and the name padded out to 4-byte boundaries
384 * with zeroes.
385 */
386 namelen = de->namelen << 2;
387 memcpy(buf, name, namelen);
388 ino = CRAMINO(de);
389 mode = de->mode;
353ab6e9 390 mutex_unlock(&read_mutex);
1da177e4
LT
391 nextoffset = offset + sizeof(*de) + namelen;
392 for (;;) {
393 if (!namelen) {
394 kfree(buf);
395 return -EIO;
396 }
397 if (buf[namelen-1])
398 break;
399 namelen--;
400 }
401 error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
402 if (error)
403 break;
404
405 offset = nextoffset;
406 filp->f_pos = offset;
407 copied++;
408 }
409 kfree(buf);
410 return 0;
411}
412
413/*
414 * Lookup and fill in the inode data..
415 */
416static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
417{
418 unsigned int offset = 0;
419 int sorted;
420
353ab6e9 421 mutex_lock(&read_mutex);
1da177e4
LT
422 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
423 while (offset < dir->i_size) {
424 struct cramfs_inode *de;
425 char *name;
426 int namelen, retval;
427
428 de = cramfs_read(dir->i_sb, OFFSET(dir) + offset, sizeof(*de)+256);
429 name = (char *)(de+1);
430
431 /* Try to take advantage of sorted directories */
432 if (sorted && (dentry->d_name.name[0] < name[0]))
433 break;
434
435 namelen = de->namelen << 2;
436 offset += sizeof(*de) + namelen;
437
438 /* Quick check that the name is roughly the right length */
439 if (((dentry->d_name.len + 3) & ~3) != namelen)
440 continue;
441
442 for (;;) {
443 if (!namelen) {
353ab6e9 444 mutex_unlock(&read_mutex);
1da177e4
LT
445 return ERR_PTR(-EIO);
446 }
447 if (name[namelen-1])
448 break;
449 namelen--;
450 }
451 if (namelen != dentry->d_name.len)
452 continue;
453 retval = memcmp(dentry->d_name.name, name, namelen);
454 if (retval > 0)
455 continue;
456 if (!retval) {
457 struct cramfs_inode entry = *de;
353ab6e9 458 mutex_unlock(&read_mutex);
1da177e4
LT
459 d_add(dentry, get_cramfs_inode(dir->i_sb, &entry));
460 return NULL;
461 }
462 /* else (retval < 0) */
463 if (sorted)
464 break;
465 }
353ab6e9 466 mutex_unlock(&read_mutex);
1da177e4
LT
467 d_add(dentry, NULL);
468 return NULL;
469}
470
471static int cramfs_readpage(struct file *file, struct page * page)
472{
473 struct inode *inode = page->mapping->host;
474 u32 maxblock, bytes_filled;
475 void *pgdata;
476
477 maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
478 bytes_filled = 0;
479 if (page->index < maxblock) {
480 struct super_block *sb = inode->i_sb;
481 u32 blkptr_offset = OFFSET(inode) + page->index*4;
482 u32 start_offset, compr_len;
483
484 start_offset = OFFSET(inode) + maxblock*4;
353ab6e9 485 mutex_lock(&read_mutex);
1da177e4
LT
486 if (page->index)
487 start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4, 4);
488 compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) - start_offset);
353ab6e9 489 mutex_unlock(&read_mutex);
1da177e4
LT
490 pgdata = kmap(page);
491 if (compr_len == 0)
492 ; /* hole */
8bb02691
PL
493 else if (compr_len > (PAGE_CACHE_SIZE << 1))
494 printk(KERN_ERR "cramfs: bad compressed blocksize %u\n", compr_len);
1da177e4 495 else {
353ab6e9 496 mutex_lock(&read_mutex);
1da177e4
LT
497 bytes_filled = cramfs_uncompress_block(pgdata,
498 PAGE_CACHE_SIZE,
499 cramfs_read(sb, start_offset, compr_len),
500 compr_len);
353ab6e9 501 mutex_unlock(&read_mutex);
1da177e4
LT
502 }
503 } else
504 pgdata = kmap(page);
505 memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
506 kunmap(page);
507 flush_dcache_page(page);
508 SetPageUptodate(page);
509 unlock_page(page);
510 return 0;
511}
512
f5e54d6e 513static const struct address_space_operations cramfs_aops = {
1da177e4
LT
514 .readpage = cramfs_readpage
515};
516
517/*
518 * Our operations:
519 */
520
521/*
522 * A directory can only readdir
523 */
4b6f5d20 524static const struct file_operations cramfs_directory_operations = {
1da177e4
LT
525 .llseek = generic_file_llseek,
526 .read = generic_read_dir,
527 .readdir = cramfs_readdir,
528};
529
754661f1 530static const struct inode_operations cramfs_dir_inode_operations = {
1da177e4
LT
531 .lookup = cramfs_lookup,
532};
533
ee9b6d61 534static const struct super_operations cramfs_ops = {
1da177e4
LT
535 .put_super = cramfs_put_super,
536 .remount_fs = cramfs_remount,
537 .statfs = cramfs_statfs,
538};
539
454e2398
DH
540static int cramfs_get_sb(struct file_system_type *fs_type,
541 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1da177e4 542{
454e2398
DH
543 return get_sb_bdev(fs_type, flags, dev_name, data, cramfs_fill_super,
544 mnt);
1da177e4
LT
545}
546
547static struct file_system_type cramfs_fs_type = {
548 .owner = THIS_MODULE,
549 .name = "cramfs",
550 .get_sb = cramfs_get_sb,
551 .kill_sb = kill_block_super,
552 .fs_flags = FS_REQUIRES_DEV,
553};
554
555static int __init init_cramfs_fs(void)
556{
50d44ed0
AD
557 int rv;
558
559 rv = cramfs_uncompress_init();
560 if (rv < 0)
561 return rv;
562 rv = register_filesystem(&cramfs_fs_type);
563 if (rv < 0)
564 cramfs_uncompress_exit();
565 return rv;
1da177e4
LT
566}
567
568static void __exit exit_cramfs_fs(void)
569{
570 cramfs_uncompress_exit();
571 unregister_filesystem(&cramfs_fs_type);
572}
573
574module_init(init_cramfs_fs)
575module_exit(exit_cramfs_fs)
576MODULE_LICENSE("GPL");