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0aa66619 PL |
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@lougher.demon.co.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/zlib.h> | |
1bcbf313 | 38 | #include <linux/magic.h> |
0aa66619 PL |
39 | |
40 | #include "squashfs_fs.h" | |
41 | #include "squashfs_fs_sb.h" | |
42 | #include "squashfs_fs_i.h" | |
43 | #include "squashfs.h" | |
44 | ||
45 | static struct file_system_type squashfs_fs_type; | |
46 | static struct super_operations squashfs_super_ops; | |
47 | ||
48 | static int supported_squashfs_filesystem(short major, short minor, short comp) | |
49 | { | |
50 | if (major < SQUASHFS_MAJOR) { | |
51 | ERROR("Major/Minor mismatch, older Squashfs %d.%d " | |
52 | "filesystems are unsupported\n", major, minor); | |
53 | return -EINVAL; | |
54 | } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { | |
55 | ERROR("Major/Minor mismatch, trying to mount newer " | |
56 | "%d.%d filesystem\n", major, minor); | |
57 | ERROR("Please update your kernel\n"); | |
58 | return -EINVAL; | |
59 | } | |
60 | ||
61 | if (comp != ZLIB_COMPRESSION) | |
62 | return -EINVAL; | |
63 | ||
64 | return 0; | |
65 | } | |
66 | ||
67 | ||
68 | static int squashfs_fill_super(struct super_block *sb, void *data, int silent) | |
69 | { | |
70 | struct squashfs_sb_info *msblk; | |
71 | struct squashfs_super_block *sblk = NULL; | |
72 | char b[BDEVNAME_SIZE]; | |
73 | struct inode *root; | |
74 | long long root_inode; | |
75 | unsigned short flags; | |
76 | unsigned int fragments; | |
77 | u64 lookup_table_start; | |
78 | int err; | |
79 | ||
80 | TRACE("Entered squashfs_fill_superblock\n"); | |
81 | ||
82 | sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); | |
83 | if (sb->s_fs_info == NULL) { | |
84 | ERROR("Failed to allocate squashfs_sb_info\n"); | |
85 | return -ENOMEM; | |
86 | } | |
87 | msblk = sb->s_fs_info; | |
88 | ||
89 | msblk->stream.workspace = kmalloc(zlib_inflate_workspacesize(), | |
90 | GFP_KERNEL); | |
91 | if (msblk->stream.workspace == NULL) { | |
92 | ERROR("Failed to allocate zlib workspace\n"); | |
93 | goto failure; | |
94 | } | |
95 | ||
96 | sblk = kzalloc(sizeof(*sblk), GFP_KERNEL); | |
97 | if (sblk == NULL) { | |
98 | ERROR("Failed to allocate squashfs_super_block\n"); | |
99 | goto failure; | |
100 | } | |
101 | ||
102 | msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE); | |
103 | msblk->devblksize_log2 = ffz(~msblk->devblksize); | |
104 | ||
105 | mutex_init(&msblk->read_data_mutex); | |
106 | mutex_init(&msblk->meta_index_mutex); | |
107 | ||
108 | /* | |
109 | * msblk->bytes_used is checked in squashfs_read_table to ensure reads | |
110 | * are not beyond filesystem end. But as we're using | |
111 | * squashfs_read_table here to read the superblock (including the value | |
112 | * of bytes_used) we need to set it to an initial sensible dummy value | |
113 | */ | |
114 | msblk->bytes_used = sizeof(*sblk); | |
115 | err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk)); | |
116 | ||
117 | if (err < 0) { | |
118 | ERROR("unable to read squashfs_super_block\n"); | |
119 | goto failed_mount; | |
120 | } | |
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 | err = -EINVAL; | |
129 | goto failed_mount; | |
130 | } | |
131 | ||
132 | /* Check the MAJOR & MINOR versions and compression type */ | |
133 | err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major), | |
134 | le16_to_cpu(sblk->s_minor), | |
135 | le16_to_cpu(sblk->compression)); | |
136 | if (err < 0) | |
137 | goto failed_mount; | |
138 | ||
139 | err = -EINVAL; | |
140 | ||
141 | /* | |
142 | * Check if there's xattrs in the filesystem. These are not | |
143 | * supported in this version, so warn that they will be ignored. | |
144 | */ | |
145 | if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK) | |
146 | ERROR("Xattrs in filesystem, these will be ignored\n"); | |
147 | ||
148 | /* Check the filesystem does not extend beyond the end of the | |
149 | block device */ | |
150 | msblk->bytes_used = le64_to_cpu(sblk->bytes_used); | |
151 | if (msblk->bytes_used < 0 || msblk->bytes_used > | |
152 | i_size_read(sb->s_bdev->bd_inode)) | |
153 | goto failed_mount; | |
154 | ||
155 | /* Check block size for sanity */ | |
156 | msblk->block_size = le32_to_cpu(sblk->block_size); | |
157 | if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) | |
158 | goto failed_mount; | |
159 | ||
160 | msblk->block_log = le16_to_cpu(sblk->block_log); | |
161 | if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) | |
162 | goto failed_mount; | |
163 | ||
164 | /* Check the root inode for sanity */ | |
165 | root_inode = le64_to_cpu(sblk->root_inode); | |
166 | if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) | |
167 | goto failed_mount; | |
168 | ||
169 | msblk->inode_table = le64_to_cpu(sblk->inode_table_start); | |
170 | msblk->directory_table = le64_to_cpu(sblk->directory_table_start); | |
171 | msblk->inodes = le32_to_cpu(sblk->inodes); | |
172 | flags = le16_to_cpu(sblk->flags); | |
173 | ||
174 | TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b)); | |
175 | TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) | |
176 | ? "un" : ""); | |
177 | TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) | |
178 | ? "un" : ""); | |
179 | TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); | |
180 | TRACE("Block size %d\n", msblk->block_size); | |
181 | TRACE("Number of inodes %d\n", msblk->inodes); | |
182 | TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments)); | |
183 | TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); | |
184 | TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); | |
185 | TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); | |
186 | TRACE("sblk->fragment_table_start %llx\n", | |
187 | (u64) le64_to_cpu(sblk->fragment_table_start)); | |
188 | TRACE("sblk->id_table_start %llx\n", | |
189 | (u64) le64_to_cpu(sblk->id_table_start)); | |
190 | ||
191 | sb->s_maxbytes = MAX_LFS_FILESIZE; | |
192 | sb->s_flags |= MS_RDONLY; | |
193 | sb->s_op = &squashfs_super_ops; | |
194 | ||
195 | err = -ENOMEM; | |
196 | ||
197 | msblk->block_cache = squashfs_cache_init("metadata", | |
198 | SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); | |
199 | if (msblk->block_cache == NULL) | |
200 | goto failed_mount; | |
201 | ||
202 | /* Allocate read_page block */ | |
203 | msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size); | |
204 | if (msblk->read_page == NULL) { | |
205 | ERROR("Failed to allocate read_page block\n"); | |
206 | goto failed_mount; | |
207 | } | |
208 | ||
209 | /* Allocate and read id index table */ | |
210 | msblk->id_table = squashfs_read_id_index_table(sb, | |
211 | le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids)); | |
212 | if (IS_ERR(msblk->id_table)) { | |
213 | err = PTR_ERR(msblk->id_table); | |
214 | msblk->id_table = NULL; | |
215 | goto failed_mount; | |
216 | } | |
217 | ||
218 | fragments = le32_to_cpu(sblk->fragments); | |
219 | if (fragments == 0) | |
220 | goto allocate_lookup_table; | |
221 | ||
222 | msblk->fragment_cache = squashfs_cache_init("fragment", | |
223 | SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); | |
224 | if (msblk->fragment_cache == NULL) { | |
225 | err = -ENOMEM; | |
226 | goto failed_mount; | |
227 | } | |
228 | ||
229 | /* Allocate and read fragment index table */ | |
230 | msblk->fragment_index = squashfs_read_fragment_index_table(sb, | |
231 | le64_to_cpu(sblk->fragment_table_start), fragments); | |
232 | if (IS_ERR(msblk->fragment_index)) { | |
233 | err = PTR_ERR(msblk->fragment_index); | |
234 | msblk->fragment_index = NULL; | |
235 | goto failed_mount; | |
236 | } | |
237 | ||
238 | allocate_lookup_table: | |
239 | lookup_table_start = le64_to_cpu(sblk->lookup_table_start); | |
240 | if (lookup_table_start == SQUASHFS_INVALID_BLK) | |
241 | goto allocate_root; | |
242 | ||
243 | /* Allocate and read inode lookup table */ | |
244 | msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, | |
245 | lookup_table_start, msblk->inodes); | |
246 | if (IS_ERR(msblk->inode_lookup_table)) { | |
247 | err = PTR_ERR(msblk->inode_lookup_table); | |
248 | msblk->inode_lookup_table = NULL; | |
249 | goto failed_mount; | |
250 | } | |
251 | ||
252 | sb->s_export_op = &squashfs_export_ops; | |
253 | ||
254 | allocate_root: | |
255 | root = new_inode(sb); | |
256 | if (!root) { | |
257 | err = -ENOMEM; | |
258 | goto failed_mount; | |
259 | } | |
260 | ||
261 | err = squashfs_read_inode(root, root_inode); | |
262 | if (err) { | |
263 | iget_failed(root); | |
264 | goto failed_mount; | |
265 | } | |
266 | insert_inode_hash(root); | |
267 | ||
268 | sb->s_root = d_alloc_root(root); | |
269 | if (sb->s_root == NULL) { | |
270 | ERROR("Root inode create failed\n"); | |
271 | err = -ENOMEM; | |
272 | iput(root); | |
273 | goto failed_mount; | |
274 | } | |
275 | ||
276 | TRACE("Leaving squashfs_fill_super\n"); | |
277 | kfree(sblk); | |
278 | return 0; | |
279 | ||
280 | failed_mount: | |
281 | squashfs_cache_delete(msblk->block_cache); | |
282 | squashfs_cache_delete(msblk->fragment_cache); | |
283 | squashfs_cache_delete(msblk->read_page); | |
284 | kfree(msblk->inode_lookup_table); | |
285 | kfree(msblk->fragment_index); | |
286 | kfree(msblk->id_table); | |
287 | kfree(msblk->stream.workspace); | |
288 | kfree(sb->s_fs_info); | |
289 | sb->s_fs_info = NULL; | |
290 | kfree(sblk); | |
291 | return err; | |
292 | ||
293 | failure: | |
294 | kfree(msblk->stream.workspace); | |
295 | kfree(sb->s_fs_info); | |
296 | sb->s_fs_info = NULL; | |
297 | return -ENOMEM; | |
298 | } | |
299 | ||
300 | ||
301 | static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) | |
302 | { | |
303 | struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; | |
304 | ||
305 | TRACE("Entered squashfs_statfs\n"); | |
306 | ||
307 | buf->f_type = SQUASHFS_MAGIC; | |
308 | buf->f_bsize = msblk->block_size; | |
309 | buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; | |
310 | buf->f_bfree = buf->f_bavail = 0; | |
311 | buf->f_files = msblk->inodes; | |
312 | buf->f_ffree = 0; | |
313 | buf->f_namelen = SQUASHFS_NAME_LEN; | |
314 | ||
315 | return 0; | |
316 | } | |
317 | ||
318 | ||
319 | static int squashfs_remount(struct super_block *sb, int *flags, char *data) | |
320 | { | |
321 | *flags |= MS_RDONLY; | |
322 | return 0; | |
323 | } | |
324 | ||
325 | ||
326 | static void squashfs_put_super(struct super_block *sb) | |
327 | { | |
328 | if (sb->s_fs_info) { | |
329 | struct squashfs_sb_info *sbi = sb->s_fs_info; | |
330 | squashfs_cache_delete(sbi->block_cache); | |
331 | squashfs_cache_delete(sbi->fragment_cache); | |
332 | squashfs_cache_delete(sbi->read_page); | |
333 | kfree(sbi->id_table); | |
334 | kfree(sbi->fragment_index); | |
335 | kfree(sbi->meta_index); | |
336 | kfree(sbi->stream.workspace); | |
337 | kfree(sb->s_fs_info); | |
338 | sb->s_fs_info = NULL; | |
339 | } | |
340 | } | |
341 | ||
342 | ||
343 | static int squashfs_get_sb(struct file_system_type *fs_type, int flags, | |
344 | const char *dev_name, void *data, | |
345 | struct vfsmount *mnt) | |
346 | { | |
347 | return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super, | |
348 | mnt); | |
349 | } | |
350 | ||
351 | ||
352 | static struct kmem_cache *squashfs_inode_cachep; | |
353 | ||
354 | ||
355 | static void init_once(void *foo) | |
356 | { | |
357 | struct squashfs_inode_info *ei = foo; | |
358 | ||
359 | inode_init_once(&ei->vfs_inode); | |
360 | } | |
361 | ||
362 | ||
363 | static int __init init_inodecache(void) | |
364 | { | |
365 | squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", | |
366 | sizeof(struct squashfs_inode_info), 0, | |
367 | SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); | |
368 | ||
369 | return squashfs_inode_cachep ? 0 : -ENOMEM; | |
370 | } | |
371 | ||
372 | ||
373 | static void destroy_inodecache(void) | |
374 | { | |
375 | kmem_cache_destroy(squashfs_inode_cachep); | |
376 | } | |
377 | ||
378 | ||
379 | static int __init init_squashfs_fs(void) | |
380 | { | |
381 | int err = init_inodecache(); | |
382 | ||
383 | if (err) | |
384 | return err; | |
385 | ||
386 | err = register_filesystem(&squashfs_fs_type); | |
387 | if (err) { | |
388 | destroy_inodecache(); | |
389 | return err; | |
390 | } | |
391 | ||
392 | printk(KERN_INFO "squashfs: version 4.0 (2009/01/03) " | |
393 | "Phillip Lougher\n"); | |
394 | ||
395 | return 0; | |
396 | } | |
397 | ||
398 | ||
399 | static void __exit exit_squashfs_fs(void) | |
400 | { | |
401 | unregister_filesystem(&squashfs_fs_type); | |
402 | destroy_inodecache(); | |
403 | } | |
404 | ||
405 | ||
406 | static struct inode *squashfs_alloc_inode(struct super_block *sb) | |
407 | { | |
408 | struct squashfs_inode_info *ei = | |
409 | kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); | |
410 | ||
411 | return ei ? &ei->vfs_inode : NULL; | |
412 | } | |
413 | ||
414 | ||
415 | static void squashfs_destroy_inode(struct inode *inode) | |
416 | { | |
417 | kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); | |
418 | } | |
419 | ||
420 | ||
421 | static struct file_system_type squashfs_fs_type = { | |
422 | .owner = THIS_MODULE, | |
423 | .name = "squashfs", | |
424 | .get_sb = squashfs_get_sb, | |
425 | .kill_sb = kill_block_super, | |
426 | .fs_flags = FS_REQUIRES_DEV | |
427 | }; | |
428 | ||
429 | static struct super_operations squashfs_super_ops = { | |
430 | .alloc_inode = squashfs_alloc_inode, | |
431 | .destroy_inode = squashfs_destroy_inode, | |
432 | .statfs = squashfs_statfs, | |
433 | .put_super = squashfs_put_super, | |
434 | .remount_fs = squashfs_remount | |
435 | }; | |
436 | ||
437 | module_init(init_squashfs_fs); | |
438 | module_exit(exit_squashfs_fs); | |
439 | MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); | |
440 | MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>"); | |
441 | MODULE_LICENSE("GPL"); |