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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
31
32 #include <linux/fs.h>
33 #include <linux/vfs.h>
34 #include <linux/slab.h>
35 #include <linux/mutex.h>
36 #include <linux/pagemap.h>
37 #include <linux/init.h>
38 #include <linux/module.h>
39 #include <linux/magic.h>
40 #include <linux/xattr.h>
41
42 #include "squashfs_fs.h"
43 #include "squashfs_fs_sb.h"
44 #include "squashfs_fs_i.h"
45 #include "squashfs.h"
46 #include "decompressor.h"
47 #include "xattr.h"
48
49 static struct file_system_type squashfs_fs_type;
50 static const struct super_operations squashfs_super_ops;
51
supported_squashfs_filesystem(short major,short minor,short id)52 static const struct squashfs_decompressor *supported_squashfs_filesystem(short
53 major, short minor, short id)
54 {
55 const struct squashfs_decompressor *decompressor;
56
57 if (major < SQUASHFS_MAJOR) {
58 ERROR("Major/Minor mismatch, older Squashfs %d.%d "
59 "filesystems are unsupported\n", major, minor);
60 return NULL;
61 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
62 ERROR("Major/Minor mismatch, trying to mount newer "
63 "%d.%d filesystem\n", major, minor);
64 ERROR("Please update your kernel\n");
65 return NULL;
66 }
67
68 decompressor = squashfs_lookup_decompressor(id);
69 if (!decompressor->supported) {
70 ERROR("Filesystem uses \"%s\" compression. This is not "
71 "supported\n", decompressor->name);
72 return NULL;
73 }
74
75 return decompressor;
76 }
77
78
squashfs_fill_super(struct super_block * sb,void * data,int silent)79 static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
80 {
81 struct squashfs_sb_info *msblk;
82 struct squashfs_super_block *sblk = NULL;
83 char b[BDEVNAME_SIZE];
84 struct inode *root;
85 long long root_inode;
86 unsigned short flags;
87 unsigned int fragments;
88 u64 lookup_table_start, xattr_id_table_start, next_table;
89 int err;
90
91 TRACE("Entered squashfs_fill_superblock\n");
92
93 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
94 if (sb->s_fs_info == NULL) {
95 ERROR("Failed to allocate squashfs_sb_info\n");
96 return -ENOMEM;
97 }
98 msblk = sb->s_fs_info;
99
100 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
101 msblk->devblksize_log2 = ffz(~msblk->devblksize);
102
103 mutex_init(&msblk->meta_index_mutex);
104
105 /*
106 * msblk->bytes_used is checked in squashfs_read_table to ensure reads
107 * are not beyond filesystem end. But as we're using
108 * squashfs_read_table here to read the superblock (including the value
109 * of bytes_used) we need to set it to an initial sensible dummy value
110 */
111 msblk->bytes_used = sizeof(*sblk);
112 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
113
114 if (IS_ERR(sblk)) {
115 ERROR("unable to read squashfs_super_block\n");
116 err = PTR_ERR(sblk);
117 sblk = NULL;
118 goto failed_mount;
119 }
120
121 err = -EINVAL;
122
123 /* Check it is a SQUASHFS superblock */
124 sb->s_magic = le32_to_cpu(sblk->s_magic);
125 if (sb->s_magic != SQUASHFS_MAGIC) {
126 if (!silent)
127 ERROR("Can't find a SQUASHFS superblock on %s\n",
128 bdevname(sb->s_bdev, b));
129 goto failed_mount;
130 }
131
132 /* Check the MAJOR & MINOR versions and lookup compression type */
133 msblk->decompressor = supported_squashfs_filesystem(
134 le16_to_cpu(sblk->s_major),
135 le16_to_cpu(sblk->s_minor),
136 le16_to_cpu(sblk->compression));
137 if (msblk->decompressor == NULL)
138 goto failed_mount;
139
140 /* Check the filesystem does not extend beyond the end of the
141 block device */
142 msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
143 if (msblk->bytes_used < 0 || msblk->bytes_used >
144 i_size_read(sb->s_bdev->bd_inode))
145 goto failed_mount;
146
147 /* Check block size for sanity */
148 msblk->block_size = le32_to_cpu(sblk->block_size);
149 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
150 goto failed_mount;
151
152 /*
153 * Check the system page size is not larger than the filesystem
154 * block size (by default 128K). This is currently not supported.
155 */
156 if (PAGE_CACHE_SIZE > msblk->block_size) {
157 ERROR("Page size > filesystem block size (%d). This is "
158 "currently not supported!\n", msblk->block_size);
159 goto failed_mount;
160 }
161
162 /* Check block log for sanity */
163 msblk->block_log = le16_to_cpu(sblk->block_log);
164 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
165 goto failed_mount;
166
167 /* Check that block_size and block_log match */
168 if (msblk->block_size != (1 << msblk->block_log))
169 goto failed_mount;
170
171 /* Check the root inode for sanity */
172 root_inode = le64_to_cpu(sblk->root_inode);
173 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
174 goto failed_mount;
175
176 msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
177 msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
178 msblk->inodes = le32_to_cpu(sblk->inodes);
179 msblk->fragments = le32_to_cpu(sblk->fragments);
180 msblk->ids = le16_to_cpu(sblk->no_ids);
181 flags = le16_to_cpu(sblk->flags);
182
183 TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b));
184 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
185 ? "un" : "");
186 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
187 ? "un" : "");
188 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
189 TRACE("Block size %d\n", msblk->block_size);
190 TRACE("Number of inodes %d\n", msblk->inodes);
191 TRACE("Number of fragments %d\n", msblk->fragments);
192 TRACE("Number of ids %d\n", msblk->ids);
193 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
194 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
195 TRACE("sblk->fragment_table_start %llx\n",
196 (u64) le64_to_cpu(sblk->fragment_table_start));
197 TRACE("sblk->id_table_start %llx\n",
198 (u64) le64_to_cpu(sblk->id_table_start));
199
200 sb->s_maxbytes = MAX_LFS_FILESIZE;
201 sb->s_flags |= MS_RDONLY;
202 sb->s_op = &squashfs_super_ops;
203
204 err = -ENOMEM;
205
206 msblk->block_cache = squashfs_cache_init("metadata",
207 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
208 if (msblk->block_cache == NULL)
209 goto failed_mount;
210
211 /* Allocate read_page block */
212 msblk->read_page = squashfs_cache_init("data",
213 squashfs_max_decompressors(), msblk->block_size);
214 if (msblk->read_page == NULL) {
215 ERROR("Failed to allocate read_page block\n");
216 goto failed_mount;
217 }
218
219 msblk->stream = squashfs_decompressor_setup(sb, flags);
220 if (IS_ERR(msblk->stream)) {
221 err = PTR_ERR(msblk->stream);
222 msblk->stream = NULL;
223 goto failed_mount;
224 }
225
226 /* Handle xattrs */
227 sb->s_xattr = squashfs_xattr_handlers;
228 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
229 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
230 next_table = msblk->bytes_used;
231 goto allocate_id_index_table;
232 }
233
234 /* Allocate and read xattr id lookup table */
235 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
236 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
237 if (IS_ERR(msblk->xattr_id_table)) {
238 ERROR("unable to read xattr id index table\n");
239 err = PTR_ERR(msblk->xattr_id_table);
240 msblk->xattr_id_table = NULL;
241 if (err != -ENOTSUPP)
242 goto failed_mount;
243 }
244 next_table = msblk->xattr_table;
245
246 allocate_id_index_table:
247 /* Allocate and read id index table */
248 msblk->id_table = squashfs_read_id_index_table(sb,
249 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
250 if (IS_ERR(msblk->id_table)) {
251 ERROR("unable to read id index table\n");
252 err = PTR_ERR(msblk->id_table);
253 msblk->id_table = NULL;
254 goto failed_mount;
255 }
256 next_table = le64_to_cpu(msblk->id_table[0]);
257
258 /* Handle inode lookup table */
259 lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
260 if (lookup_table_start == SQUASHFS_INVALID_BLK)
261 goto handle_fragments;
262
263 /* Allocate and read inode lookup table */
264 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
265 lookup_table_start, next_table, msblk->inodes);
266 if (IS_ERR(msblk->inode_lookup_table)) {
267 ERROR("unable to read inode lookup table\n");
268 err = PTR_ERR(msblk->inode_lookup_table);
269 msblk->inode_lookup_table = NULL;
270 goto failed_mount;
271 }
272 next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
273
274 sb->s_export_op = &squashfs_export_ops;
275
276 handle_fragments:
277 fragments = msblk->fragments;
278 if (fragments == 0)
279 goto check_directory_table;
280
281 msblk->fragment_cache = squashfs_cache_init("fragment",
282 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
283 if (msblk->fragment_cache == NULL) {
284 err = -ENOMEM;
285 goto failed_mount;
286 }
287
288 /* Allocate and read fragment index table */
289 msblk->fragment_index = squashfs_read_fragment_index_table(sb,
290 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
291 if (IS_ERR(msblk->fragment_index)) {
292 ERROR("unable to read fragment index table\n");
293 err = PTR_ERR(msblk->fragment_index);
294 msblk->fragment_index = NULL;
295 goto failed_mount;
296 }
297 next_table = le64_to_cpu(msblk->fragment_index[0]);
298
299 check_directory_table:
300 /* Sanity check directory_table */
301 if (msblk->directory_table > next_table) {
302 err = -EINVAL;
303 goto failed_mount;
304 }
305
306 /* Sanity check inode_table */
307 if (msblk->inode_table >= msblk->directory_table) {
308 err = -EINVAL;
309 goto failed_mount;
310 }
311
312 /* allocate root */
313 root = new_inode(sb);
314 if (!root) {
315 err = -ENOMEM;
316 goto failed_mount;
317 }
318
319 err = squashfs_read_inode(root, root_inode);
320 if (err) {
321 make_bad_inode(root);
322 iput(root);
323 goto failed_mount;
324 }
325 insert_inode_hash(root);
326
327 sb->s_root = d_make_root(root);
328 if (sb->s_root == NULL) {
329 ERROR("Root inode create failed\n");
330 err = -ENOMEM;
331 goto failed_mount;
332 }
333
334 TRACE("Leaving squashfs_fill_super\n");
335 kfree(sblk);
336 return 0;
337
338 failed_mount:
339 squashfs_cache_delete(msblk->block_cache);
340 squashfs_cache_delete(msblk->fragment_cache);
341 squashfs_cache_delete(msblk->read_page);
342 squashfs_decompressor_destroy(msblk);
343 kfree(msblk->inode_lookup_table);
344 kfree(msblk->fragment_index);
345 kfree(msblk->id_table);
346 kfree(msblk->xattr_id_table);
347 kfree(sb->s_fs_info);
348 sb->s_fs_info = NULL;
349 kfree(sblk);
350 return err;
351 }
352
353
squashfs_statfs(struct dentry * dentry,struct kstatfs * buf)354 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
355 {
356 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
357 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
358
359 TRACE("Entered squashfs_statfs\n");
360
361 buf->f_type = SQUASHFS_MAGIC;
362 buf->f_bsize = msblk->block_size;
363 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
364 buf->f_bfree = buf->f_bavail = 0;
365 buf->f_files = msblk->inodes;
366 buf->f_ffree = 0;
367 buf->f_namelen = SQUASHFS_NAME_LEN;
368 buf->f_fsid.val[0] = (u32)id;
369 buf->f_fsid.val[1] = (u32)(id >> 32);
370
371 return 0;
372 }
373
374
squashfs_remount(struct super_block * sb,int * flags,char * data)375 static int squashfs_remount(struct super_block *sb, int *flags, char *data)
376 {
377 sync_filesystem(sb);
378 *flags |= MS_RDONLY;
379 return 0;
380 }
381
382
squashfs_put_super(struct super_block * sb)383 static void squashfs_put_super(struct super_block *sb)
384 {
385 if (sb->s_fs_info) {
386 struct squashfs_sb_info *sbi = sb->s_fs_info;
387 squashfs_cache_delete(sbi->block_cache);
388 squashfs_cache_delete(sbi->fragment_cache);
389 squashfs_cache_delete(sbi->read_page);
390 squashfs_decompressor_destroy(sbi);
391 kfree(sbi->id_table);
392 kfree(sbi->fragment_index);
393 kfree(sbi->meta_index);
394 kfree(sbi->inode_lookup_table);
395 kfree(sbi->xattr_id_table);
396 kfree(sb->s_fs_info);
397 sb->s_fs_info = NULL;
398 }
399 }
400
401
squashfs_mount(struct file_system_type * fs_type,int flags,const char * dev_name,void * data)402 static struct dentry *squashfs_mount(struct file_system_type *fs_type,
403 int flags, const char *dev_name, void *data)
404 {
405 return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super);
406 }
407
408
409 static struct kmem_cache *squashfs_inode_cachep;
410
411
init_once(void * foo)412 static void init_once(void *foo)
413 {
414 struct squashfs_inode_info *ei = foo;
415
416 inode_init_once(&ei->vfs_inode);
417 }
418
419
init_inodecache(void)420 static int __init init_inodecache(void)
421 {
422 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
423 sizeof(struct squashfs_inode_info), 0,
424 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once);
425
426 return squashfs_inode_cachep ? 0 : -ENOMEM;
427 }
428
429
destroy_inodecache(void)430 static void destroy_inodecache(void)
431 {
432 /*
433 * Make sure all delayed rcu free inodes are flushed before we
434 * destroy cache.
435 */
436 rcu_barrier();
437 kmem_cache_destroy(squashfs_inode_cachep);
438 }
439
440
init_squashfs_fs(void)441 static int __init init_squashfs_fs(void)
442 {
443 int err = init_inodecache();
444
445 if (err)
446 return err;
447
448 if (!squashfs_init_read_wq()) {
449 destroy_inodecache();
450 return -ENOMEM;
451 }
452
453 err = register_filesystem(&squashfs_fs_type);
454 if (err) {
455 destroy_inodecache();
456 squashfs_destroy_read_wq();
457 return err;
458 }
459
460 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
461
462 return 0;
463 }
464
465
exit_squashfs_fs(void)466 static void __exit exit_squashfs_fs(void)
467 {
468 unregister_filesystem(&squashfs_fs_type);
469 destroy_inodecache();
470 squashfs_destroy_read_wq();
471 }
472
473
squashfs_alloc_inode(struct super_block * sb)474 static struct inode *squashfs_alloc_inode(struct super_block *sb)
475 {
476 struct squashfs_inode_info *ei =
477 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
478
479 return ei ? &ei->vfs_inode : NULL;
480 }
481
482
squashfs_i_callback(struct rcu_head * head)483 static void squashfs_i_callback(struct rcu_head *head)
484 {
485 struct inode *inode = container_of(head, struct inode, i_rcu);
486 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
487 }
488
squashfs_destroy_inode(struct inode * inode)489 static void squashfs_destroy_inode(struct inode *inode)
490 {
491 call_rcu(&inode->i_rcu, squashfs_i_callback);
492 }
493
494
495 static struct file_system_type squashfs_fs_type = {
496 .owner = THIS_MODULE,
497 .name = "squashfs",
498 .mount = squashfs_mount,
499 .kill_sb = kill_block_super,
500 .fs_flags = FS_REQUIRES_DEV
501 };
502 MODULE_ALIAS_FS("squashfs");
503
504 static const struct super_operations squashfs_super_ops = {
505 .alloc_inode = squashfs_alloc_inode,
506 .destroy_inode = squashfs_destroy_inode,
507 .statfs = squashfs_statfs,
508 .put_super = squashfs_put_super,
509 .remount_fs = squashfs_remount
510 };
511
512 module_init(init_squashfs_fs);
513 module_exit(exit_squashfs_fs);
514 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
515 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
516 MODULE_LICENSE("GPL");
517