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1 | /* |
2 | * Squashfs - a compressed read only filesystem for Linux |
3 | * |
4 | * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 |
5 | * Phillip Lougher <phillip@squashfs.org.uk> |
6 | * |
7 | * This program is free software; you can redistribute it and/or |
8 | * modify it under the terms of the GNU General Public License |
9 | * as published by the Free Software Foundation; either version 2, |
10 | * or (at your option) any later version. |
11 | * |
12 | * This program is distributed in the hope that it will be useful, |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
15 | * GNU General Public License for more details. |
16 | * |
17 | * You should have received a copy of the GNU General Public License |
18 | * along with this program; if not, write to the Free Software |
19 | * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
20 | * |
21 | * super.c |
22 | */ |
23 | |
24 | /* |
25 | * This file implements code to read the superblock, read and initialise |
26 | * in-memory structures at mount time, and all the VFS glue code to register |
27 | * the filesystem. |
28 | */ |
29 | |
30 | #include <linux/fs.h> |
31 | #include <linux/vfs.h> |
32 | #include <linux/slab.h> |
33 | #include <linux/mutex.h> |
34 | #include <linux/pagemap.h> |
35 | #include <linux/init.h> |
36 | #include <linux/module.h> |
37 | #include <linux/magic.h> |
38 | #include <linux/xattr.h> |
39 | |
40 | #include "squashfs_fs.h" |
41 | #include "squashfs_fs_sb.h" |
42 | #include "squashfs_fs_i.h" |
43 | #include "squashfs.h" |
44 | #include "decompressor.h" |
45 | #include "xattr.h" |
46 | |
47 | static struct file_system_type squashfs_fs_type; |
48 | static const struct super_operations squashfs_super_ops; |
49 | |
50 | static const struct squashfs_decompressor *supported_squashfs_filesystem(short |
51 | major, short minor, short id) |
52 | { |
53 | const struct squashfs_decompressor *decompressor; |
54 | |
55 | if (major < SQUASHFS_MAJOR) { |
56 | ERROR("Major/Minor mismatch, older Squashfs %d.%d " |
57 | "filesystems are unsupported\n", major, minor); |
58 | return NULL; |
59 | } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { |
60 | ERROR("Major/Minor mismatch, trying to mount newer " |
61 | "%d.%d filesystem\n", major, minor); |
62 | ERROR("Please update your kernel\n"); |
63 | return NULL; |
64 | } |
65 | |
66 | decompressor = squashfs_lookup_decompressor(id); |
67 | if (!decompressor->supported) { |
68 | ERROR("Filesystem uses \"%s\" compression. This is not " |
69 | "supported\n", decompressor->name); |
70 | return NULL; |
71 | } |
72 | |
73 | return decompressor; |
74 | } |
75 | |
76 | |
77 | static int squashfs_fill_super(struct super_block *sb, void *data, int silent) |
78 | { |
79 | struct squashfs_sb_info *msblk; |
80 | struct squashfs_super_block *sblk = NULL; |
81 | char b[BDEVNAME_SIZE]; |
82 | struct inode *root; |
83 | long long root_inode; |
84 | unsigned short flags; |
85 | unsigned int fragments; |
86 | u64 lookup_table_start, xattr_id_table_start, next_table; |
87 | int err; |
88 | |
89 | TRACE("Entered squashfs_fill_superblock\n"); |
90 | |
91 | sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); |
92 | if (sb->s_fs_info == NULL) { |
93 | ERROR("Failed to allocate squashfs_sb_info\n"); |
94 | return -ENOMEM; |
95 | } |
96 | msblk = sb->s_fs_info; |
97 | |
98 | msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE); |
99 | msblk->devblksize_log2 = ffz(~msblk->devblksize); |
100 | |
101 | mutex_init(&msblk->read_data_mutex); |
102 | mutex_init(&msblk->meta_index_mutex); |
103 | |
104 | /* |
105 | * msblk->bytes_used is checked in squashfs_read_table to ensure reads |
106 | * are not beyond filesystem end. But as we're using |
107 | * squashfs_read_table here to read the superblock (including the value |
108 | * of bytes_used) we need to set it to an initial sensible dummy value |
109 | */ |
110 | msblk->bytes_used = sizeof(*sblk); |
111 | sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk)); |
112 | |
113 | if (IS_ERR(sblk)) { |
114 | ERROR("unable to read squashfs_super_block\n"); |
115 | err = PTR_ERR(sblk); |
116 | sblk = NULL; |
117 | goto failed_mount; |
118 | } |
119 | |
120 | err = -EINVAL; |
121 | |
122 | /* Check it is a SQUASHFS superblock */ |
123 | sb->s_magic = le32_to_cpu(sblk->s_magic); |
124 | if (sb->s_magic != SQUASHFS_MAGIC) { |
125 | if (!silent) |
126 | ERROR("Can't find a SQUASHFS superblock on %s\n", |
127 | bdevname(sb->s_bdev, b)); |
128 | goto failed_mount; |
129 | } |
130 | |
131 | /* Check the MAJOR & MINOR versions and lookup compression type */ |
132 | msblk->decompressor = supported_squashfs_filesystem( |
133 | le16_to_cpu(sblk->s_major), |
134 | le16_to_cpu(sblk->s_minor), |
135 | le16_to_cpu(sblk->compression)); |
136 | if (msblk->decompressor == NULL) |
137 | goto failed_mount; |
138 | |
139 | /* Check the filesystem does not extend beyond the end of the |
140 | block device */ |
141 | msblk->bytes_used = le64_to_cpu(sblk->bytes_used); |
142 | if (msblk->bytes_used < 0 || msblk->bytes_used > |
143 | i_size_read(sb->s_bdev->bd_inode)) |
144 | goto failed_mount; |
145 | |
146 | /* Check block size for sanity */ |
147 | msblk->block_size = le32_to_cpu(sblk->block_size); |
148 | if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) |
149 | goto failed_mount; |
150 | |
151 | /* |
152 | * Check the system page size is not larger than the filesystem |
153 | * block size (by default 128K). This is currently not supported. |
154 | */ |
155 | if (PAGE_CACHE_SIZE > msblk->block_size) { |
156 | ERROR("Page size > filesystem block size (%d). This is " |
157 | "currently not supported!\n", msblk->block_size); |
158 | goto failed_mount; |
159 | } |
160 | |
161 | msblk->block_log = le16_to_cpu(sblk->block_log); |
162 | if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) |
163 | goto failed_mount; |
164 | |
165 | /* Check the root inode for sanity */ |
166 | root_inode = le64_to_cpu(sblk->root_inode); |
167 | if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) |
168 | goto failed_mount; |
169 | |
170 | msblk->inode_table = le64_to_cpu(sblk->inode_table_start); |
171 | msblk->directory_table = le64_to_cpu(sblk->directory_table_start); |
172 | msblk->inodes = le32_to_cpu(sblk->inodes); |
173 | flags = le16_to_cpu(sblk->flags); |
174 | |
175 | TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b)); |
176 | TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) |
177 | ? "un" : ""); |
178 | TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) |
179 | ? "un" : ""); |
180 | TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); |
181 | TRACE("Block size %d\n", msblk->block_size); |
182 | TRACE("Number of inodes %d\n", msblk->inodes); |
183 | TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments)); |
184 | TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); |
185 | TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); |
186 | TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); |
187 | TRACE("sblk->fragment_table_start %llx\n", |
188 | (u64) le64_to_cpu(sblk->fragment_table_start)); |
189 | TRACE("sblk->id_table_start %llx\n", |
190 | (u64) le64_to_cpu(sblk->id_table_start)); |
191 | |
192 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
193 | sb->s_flags |= MS_RDONLY; |
194 | sb->s_op = &squashfs_super_ops; |
195 | |
196 | err = -ENOMEM; |
197 | |
198 | msblk->block_cache = squashfs_cache_init("metadata", |
199 | SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); |
200 | if (msblk->block_cache == NULL) |
201 | goto failed_mount; |
202 | |
203 | /* Allocate read_page block */ |
204 | msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size); |
205 | if (msblk->read_page == NULL) { |
206 | ERROR("Failed to allocate read_page block\n"); |
207 | goto failed_mount; |
208 | } |
209 | |
210 | msblk->stream = squashfs_decompressor_init(sb, flags); |
211 | if (IS_ERR(msblk->stream)) { |
212 | err = PTR_ERR(msblk->stream); |
213 | msblk->stream = NULL; |
214 | goto failed_mount; |
215 | } |
216 | |
217 | /* Handle xattrs */ |
218 | sb->s_xattr = squashfs_xattr_handlers; |
219 | xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start); |
220 | if (xattr_id_table_start == SQUASHFS_INVALID_BLK) { |
221 | next_table = msblk->bytes_used; |
222 | goto allocate_id_index_table; |
223 | } |
224 | |
225 | /* Allocate and read xattr id lookup table */ |
226 | msblk->xattr_id_table = squashfs_read_xattr_id_table(sb, |
227 | xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids); |
228 | if (IS_ERR(msblk->xattr_id_table)) { |
229 | ERROR("unable to read xattr id index table\n"); |
230 | err = PTR_ERR(msblk->xattr_id_table); |
231 | msblk->xattr_id_table = NULL; |
232 | if (err != -ENOTSUPP) |
233 | goto failed_mount; |
234 | } |
235 | next_table = msblk->xattr_table; |
236 | |
237 | allocate_id_index_table: |
238 | /* Allocate and read id index table */ |
239 | msblk->id_table = squashfs_read_id_index_table(sb, |
240 | le64_to_cpu(sblk->id_table_start), next_table, |
241 | le16_to_cpu(sblk->no_ids)); |
242 | if (IS_ERR(msblk->id_table)) { |
243 | ERROR("unable to read id index table\n"); |
244 | err = PTR_ERR(msblk->id_table); |
245 | msblk->id_table = NULL; |
246 | goto failed_mount; |
247 | } |
248 | next_table = le64_to_cpu(msblk->id_table[0]); |
249 | |
250 | /* Handle inode lookup table */ |
251 | lookup_table_start = le64_to_cpu(sblk->lookup_table_start); |
252 | if (lookup_table_start == SQUASHFS_INVALID_BLK) |
253 | goto handle_fragments; |
254 | |
255 | /* Allocate and read inode lookup table */ |
256 | msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, |
257 | lookup_table_start, next_table, msblk->inodes); |
258 | if (IS_ERR(msblk->inode_lookup_table)) { |
259 | ERROR("unable to read inode lookup table\n"); |
260 | err = PTR_ERR(msblk->inode_lookup_table); |
261 | msblk->inode_lookup_table = NULL; |
262 | goto failed_mount; |
263 | } |
264 | next_table = le64_to_cpu(msblk->inode_lookup_table[0]); |
265 | |
266 | sb->s_export_op = &squashfs_export_ops; |
267 | |
268 | handle_fragments: |
269 | fragments = le32_to_cpu(sblk->fragments); |
270 | if (fragments == 0) |
271 | goto check_directory_table; |
272 | |
273 | msblk->fragment_cache = squashfs_cache_init("fragment", |
274 | SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); |
275 | if (msblk->fragment_cache == NULL) { |
276 | err = -ENOMEM; |
277 | goto failed_mount; |
278 | } |
279 | |
280 | /* Allocate and read fragment index table */ |
281 | msblk->fragment_index = squashfs_read_fragment_index_table(sb, |
282 | le64_to_cpu(sblk->fragment_table_start), next_table, fragments); |
283 | if (IS_ERR(msblk->fragment_index)) { |
284 | ERROR("unable to read fragment index table\n"); |
285 | err = PTR_ERR(msblk->fragment_index); |
286 | msblk->fragment_index = NULL; |
287 | goto failed_mount; |
288 | } |
289 | next_table = le64_to_cpu(msblk->fragment_index[0]); |
290 | |
291 | check_directory_table: |
292 | /* Sanity check directory_table */ |
293 | if (msblk->directory_table >= next_table) { |
294 | err = -EINVAL; |
295 | goto failed_mount; |
296 | } |
297 | |
298 | /* Sanity check inode_table */ |
299 | if (msblk->inode_table >= msblk->directory_table) { |
300 | err = -EINVAL; |
301 | goto failed_mount; |
302 | } |
303 | |
304 | /* allocate root */ |
305 | root = new_inode(sb); |
306 | if (!root) { |
307 | err = -ENOMEM; |
308 | goto failed_mount; |
309 | } |
310 | |
311 | err = squashfs_read_inode(root, root_inode); |
312 | if (err) { |
313 | make_bad_inode(root); |
314 | iput(root); |
315 | goto failed_mount; |
316 | } |
317 | insert_inode_hash(root); |
318 | |
319 | sb->s_root = d_alloc_root(root); |
320 | if (sb->s_root == NULL) { |
321 | ERROR("Root inode create failed\n"); |
322 | err = -ENOMEM; |
323 | iput(root); |
324 | goto failed_mount; |
325 | } |
326 | |
327 | TRACE("Leaving squashfs_fill_super\n"); |
328 | kfree(sblk); |
329 | return 0; |
330 | |
331 | failed_mount: |
332 | squashfs_cache_delete(msblk->block_cache); |
333 | squashfs_cache_delete(msblk->fragment_cache); |
334 | squashfs_cache_delete(msblk->read_page); |
335 | squashfs_decompressor_free(msblk, msblk->stream); |
336 | kfree(msblk->inode_lookup_table); |
337 | kfree(msblk->fragment_index); |
338 | kfree(msblk->id_table); |
339 | kfree(msblk->xattr_id_table); |
340 | kfree(sb->s_fs_info); |
341 | sb->s_fs_info = NULL; |
342 | kfree(sblk); |
343 | return err; |
344 | } |
345 | |
346 | |
347 | static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) |
348 | { |
349 | struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; |
350 | u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); |
351 | |
352 | TRACE("Entered squashfs_statfs\n"); |
353 | |
354 | buf->f_type = SQUASHFS_MAGIC; |
355 | buf->f_bsize = msblk->block_size; |
356 | buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; |
357 | buf->f_bfree = buf->f_bavail = 0; |
358 | buf->f_files = msblk->inodes; |
359 | buf->f_ffree = 0; |
360 | buf->f_namelen = SQUASHFS_NAME_LEN; |
361 | buf->f_fsid.val[0] = (u32)id; |
362 | buf->f_fsid.val[1] = (u32)(id >> 32); |
363 | |
364 | return 0; |
365 | } |
366 | |
367 | |
368 | static int squashfs_remount(struct super_block *sb, int *flags, char *data) |
369 | { |
370 | *flags |= MS_RDONLY; |
371 | return 0; |
372 | } |
373 | |
374 | |
375 | static void squashfs_put_super(struct super_block *sb) |
376 | { |
377 | if (sb->s_fs_info) { |
378 | struct squashfs_sb_info *sbi = sb->s_fs_info; |
379 | squashfs_cache_delete(sbi->block_cache); |
380 | squashfs_cache_delete(sbi->fragment_cache); |
381 | squashfs_cache_delete(sbi->read_page); |
382 | squashfs_decompressor_free(sbi, sbi->stream); |
383 | kfree(sbi->id_table); |
384 | kfree(sbi->fragment_index); |
385 | kfree(sbi->meta_index); |
386 | kfree(sbi->inode_lookup_table); |
387 | kfree(sbi->xattr_id_table); |
388 | kfree(sb->s_fs_info); |
389 | sb->s_fs_info = NULL; |
390 | } |
391 | } |
392 | |
393 | |
394 | static struct dentry *squashfs_mount(struct file_system_type *fs_type, |
395 | int flags, const char *dev_name, void *data) |
396 | { |
397 | return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super); |
398 | } |
399 | |
400 | |
401 | static struct kmem_cache *squashfs_inode_cachep; |
402 | |
403 | |
404 | static void init_once(void *foo) |
405 | { |
406 | struct squashfs_inode_info *ei = foo; |
407 | |
408 | inode_init_once(&ei->vfs_inode); |
409 | } |
410 | |
411 | |
412 | static int __init init_inodecache(void) |
413 | { |
414 | squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", |
415 | sizeof(struct squashfs_inode_info), 0, |
416 | SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); |
417 | |
418 | return squashfs_inode_cachep ? 0 : -ENOMEM; |
419 | } |
420 | |
421 | |
422 | static void destroy_inodecache(void) |
423 | { |
424 | kmem_cache_destroy(squashfs_inode_cachep); |
425 | } |
426 | |
427 | |
428 | static int __init init_squashfs_fs(void) |
429 | { |
430 | int err = init_inodecache(); |
431 | |
432 | if (err) |
433 | return err; |
434 | |
435 | err = register_filesystem(&squashfs_fs_type); |
436 | if (err) { |
437 | destroy_inodecache(); |
438 | return err; |
439 | } |
440 | |
441 | printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) " |
442 | "Phillip Lougher\n"); |
443 | |
444 | return 0; |
445 | } |
446 | |
447 | |
448 | static void __exit exit_squashfs_fs(void) |
449 | { |
450 | unregister_filesystem(&squashfs_fs_type); |
451 | destroy_inodecache(); |
452 | } |
453 | |
454 | |
455 | static struct inode *squashfs_alloc_inode(struct super_block *sb) |
456 | { |
457 | struct squashfs_inode_info *ei = |
458 | kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); |
459 | |
460 | return ei ? &ei->vfs_inode : NULL; |
461 | } |
462 | |
463 | |
464 | static void squashfs_i_callback(struct rcu_head *head) |
465 | { |
466 | struct inode *inode = container_of(head, struct inode, i_rcu); |
467 | INIT_LIST_HEAD(&inode->i_dentry); |
468 | kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); |
469 | } |
470 | |
471 | static void squashfs_destroy_inode(struct inode *inode) |
472 | { |
473 | call_rcu(&inode->i_rcu, squashfs_i_callback); |
474 | } |
475 | |
476 | |
477 | static struct file_system_type squashfs_fs_type = { |
478 | .owner = THIS_MODULE, |
479 | .name = "squashfs", |
480 | .mount = squashfs_mount, |
481 | .kill_sb = kill_block_super, |
482 | .fs_flags = FS_REQUIRES_DEV |
483 | }; |
484 | |
485 | static const struct super_operations squashfs_super_ops = { |
486 | .alloc_inode = squashfs_alloc_inode, |
487 | .destroy_inode = squashfs_destroy_inode, |
488 | .statfs = squashfs_statfs, |
489 | .put_super = squashfs_put_super, |
490 | .remount_fs = squashfs_remount |
491 | }; |
492 | |
493 | module_init(init_squashfs_fs); |
494 | module_exit(exit_squashfs_fs); |
495 | MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); |
496 | MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>"); |
497 | MODULE_LICENSE("GPL"); |
498 |
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