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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
d7f2ff67 5 * Phillip Lougher <phillip@squashfs.org.uk>
0aa66619
PL
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>
1bcbf313 37#include <linux/magic.h>
4b5397dc 38#include <linux/xattr.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"
4c0f0bb2 44#include "decompressor.h"
01e5b4e4 45#include "xattr.h"
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PL
46
47static struct file_system_type squashfs_fs_type;
b87221de 48static const struct super_operations squashfs_super_ops;
0aa66619 49
4c0f0bb2
PL
50static const struct squashfs_decompressor *supported_squashfs_filesystem(short
51 major, short minor, short id)
0aa66619 52{
4c0f0bb2
PL
53 const struct squashfs_decompressor *decompressor;
54
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PL
55 if (major < SQUASHFS_MAJOR) {
56 ERROR("Major/Minor mismatch, older Squashfs %d.%d "
57 "filesystems are unsupported\n", major, minor);
4c0f0bb2 58 return NULL;
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PL
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");
4c0f0bb2 63 return NULL;
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PL
64 }
65
4c0f0bb2
PL
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 }
0aa66619 72
4c0f0bb2 73 return decompressor;
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PL
74}
75
76
77static 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;
37986f63 86 u64 lookup_table_start, xattr_id_table_start, next_table;
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PL
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
7657cacf 98 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
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PL
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);
82de647e 111 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
0aa66619 112
82de647e 113 if (IS_ERR(sblk)) {
0aa66619 114 ERROR("unable to read squashfs_super_block\n");
82de647e
PL
115 err = PTR_ERR(sblk);
116 sblk = NULL;
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PL
117 goto failed_mount;
118 }
119
4c0f0bb2
PL
120 err = -EINVAL;
121
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PL
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));
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PL
128 goto failed_mount;
129 }
130
4c0f0bb2
PL
131 /* Check the MAJOR & MINOR versions and lookup compression type */
132 msblk->decompressor = supported_squashfs_filesystem(
133 le16_to_cpu(sblk->s_major),
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PL
134 le16_to_cpu(sblk->s_minor),
135 le16_to_cpu(sblk->compression));
4c0f0bb2 136 if (msblk->decompressor == NULL)
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PL
137 goto failed_mount;
138
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PL
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
fffb47b8
PL
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
4b0180a4 161 /* Check block log for sanity */
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PL
162 msblk->block_log = le16_to_cpu(sblk->block_log);
163 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
164 goto failed_mount;
165
4b0180a4
PL
166 /* Check that block_size and block_log match */
167 if (msblk->block_size != (1 << msblk->block_log))
168 goto failed_mount;
169
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PL
170 /* Check the root inode for sanity */
171 root_inode = le64_to_cpu(sblk->root_inode);
172 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
173 goto failed_mount;
174
175 msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
176 msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
177 msblk->inodes = le32_to_cpu(sblk->inodes);
178 flags = le16_to_cpu(sblk->flags);
179
180 TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b));
181 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
182 ? "un" : "");
183 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
184 ? "un" : "");
185 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
186 TRACE("Block size %d\n", msblk->block_size);
187 TRACE("Number of inodes %d\n", msblk->inodes);
188 TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments));
189 TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
190 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
191 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
192 TRACE("sblk->fragment_table_start %llx\n",
193 (u64) le64_to_cpu(sblk->fragment_table_start));
194 TRACE("sblk->id_table_start %llx\n",
195 (u64) le64_to_cpu(sblk->id_table_start));
196
197 sb->s_maxbytes = MAX_LFS_FILESIZE;
198 sb->s_flags |= MS_RDONLY;
199 sb->s_op = &squashfs_super_ops;
200
201 err = -ENOMEM;
202
203 msblk->block_cache = squashfs_cache_init("metadata",
204 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
205 if (msblk->block_cache == NULL)
206 goto failed_mount;
207
208 /* Allocate read_page block */
209 msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size);
210 if (msblk->read_page == NULL) {
211 ERROR("Failed to allocate read_page block\n");
212 goto failed_mount;
213 }
214
b7fc0ff0
PL
215 msblk->stream = squashfs_decompressor_init(sb, flags);
216 if (IS_ERR(msblk->stream)) {
217 err = PTR_ERR(msblk->stream);
218 msblk->stream = NULL;
219 goto failed_mount;
220 }
221
76e002f7
PL
222 /* Handle xattrs */
223 sb->s_xattr = squashfs_xattr_handlers;
224 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
37986f63
PL
225 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
226 next_table = msblk->bytes_used;
76e002f7 227 goto allocate_id_index_table;
37986f63 228 }
76e002f7
PL
229
230 /* Allocate and read xattr id lookup table */
231 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
232 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
233 if (IS_ERR(msblk->xattr_id_table)) {
234 ERROR("unable to read xattr id index table\n");
235 err = PTR_ERR(msblk->xattr_id_table);
236 msblk->xattr_id_table = NULL;
237 if (err != -ENOTSUPP)
238 goto failed_mount;
239 }
37986f63 240 next_table = msblk->xattr_table;
76e002f7
PL
241
242allocate_id_index_table:
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PL
243 /* Allocate and read id index table */
244 msblk->id_table = squashfs_read_id_index_table(sb,
37986f63
PL
245 le64_to_cpu(sblk->id_table_start), next_table,
246 le16_to_cpu(sblk->no_ids));
0aa66619 247 if (IS_ERR(msblk->id_table)) {
82de647e 248 ERROR("unable to read id index table\n");
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PL
249 err = PTR_ERR(msblk->id_table);
250 msblk->id_table = NULL;
251 goto failed_mount;
252 }
d5b72ce1 253 next_table = le64_to_cpu(msblk->id_table[0]);
0aa66619 254
76e002f7
PL
255 /* Handle inode lookup table */
256 lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
257 if (lookup_table_start == SQUASHFS_INVALID_BLK)
258 goto handle_fragments;
259
260 /* Allocate and read inode lookup table */
261 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
ac51a0a7 262 lookup_table_start, next_table, msblk->inodes);
76e002f7
PL
263 if (IS_ERR(msblk->inode_lookup_table)) {
264 ERROR("unable to read inode lookup table\n");
265 err = PTR_ERR(msblk->inode_lookup_table);
266 msblk->inode_lookup_table = NULL;
267 goto failed_mount;
268 }
d5b72ce1 269 next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
76e002f7
PL
270
271 sb->s_export_op = &squashfs_export_ops;
272
273handle_fragments:
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PL
274 fragments = le32_to_cpu(sblk->fragments);
275 if (fragments == 0)
1094a4a6 276 goto check_directory_table;
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PL
277
278 msblk->fragment_cache = squashfs_cache_init("fragment",
279 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
280 if (msblk->fragment_cache == NULL) {
281 err = -ENOMEM;
282 goto failed_mount;
283 }
284
285 /* Allocate and read fragment index table */
286 msblk->fragment_index = squashfs_read_fragment_index_table(sb,
1cac63cc 287 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
0aa66619 288 if (IS_ERR(msblk->fragment_index)) {
82de647e 289 ERROR("unable to read fragment index table\n");
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PL
290 err = PTR_ERR(msblk->fragment_index);
291 msblk->fragment_index = NULL;
292 goto failed_mount;
293 }
d5b72ce1 294 next_table = le64_to_cpu(msblk->fragment_index[0]);
0aa66619 295
1094a4a6
PL
296check_directory_table:
297 /* Sanity check directory_table */
cc37f75a 298 if (msblk->directory_table > next_table) {
1094a4a6
PL
299 err = -EINVAL;
300 goto failed_mount;
301 }
302
303 /* Sanity check inode_table */
304 if (msblk->inode_table >= msblk->directory_table) {
305 err = -EINVAL;
306 goto failed_mount;
307 }
308
309 /* allocate root */
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PL
310 root = new_inode(sb);
311 if (!root) {
312 err = -ENOMEM;
313 goto failed_mount;
314 }
315
316 err = squashfs_read_inode(root, root_inode);
317 if (err) {
1cb08e97
PL
318 make_bad_inode(root);
319 iput(root);
0aa66619
PL
320 goto failed_mount;
321 }
322 insert_inode_hash(root);
323
48fde701 324 sb->s_root = d_make_root(root);
0aa66619
PL
325 if (sb->s_root == NULL) {
326 ERROR("Root inode create failed\n");
327 err = -ENOMEM;
0aa66619
PL
328 goto failed_mount;
329 }
330
331 TRACE("Leaving squashfs_fill_super\n");
332 kfree(sblk);
333 return 0;
334
335failed_mount:
336 squashfs_cache_delete(msblk->block_cache);
337 squashfs_cache_delete(msblk->fragment_cache);
338 squashfs_cache_delete(msblk->read_page);
4c0f0bb2 339 squashfs_decompressor_free(msblk, msblk->stream);
0aa66619
PL
340 kfree(msblk->inode_lookup_table);
341 kfree(msblk->fragment_index);
342 kfree(msblk->id_table);
4b5397dc 343 kfree(msblk->xattr_id_table);
0aa66619
PL
344 kfree(sb->s_fs_info);
345 sb->s_fs_info = NULL;
346 kfree(sblk);
347 return err;
0aa66619
PL
348}
349
350
351static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
352{
353 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
2fc7f562 354 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
0aa66619
PL
355
356 TRACE("Entered squashfs_statfs\n");
357
358 buf->f_type = SQUASHFS_MAGIC;
359 buf->f_bsize = msblk->block_size;
360 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
361 buf->f_bfree = buf->f_bavail = 0;
362 buf->f_files = msblk->inodes;
363 buf->f_ffree = 0;
364 buf->f_namelen = SQUASHFS_NAME_LEN;
2fc7f562
CL
365 buf->f_fsid.val[0] = (u32)id;
366 buf->f_fsid.val[1] = (u32)(id >> 32);
0aa66619
PL
367
368 return 0;
369}
370
371
372static int squashfs_remount(struct super_block *sb, int *flags, char *data)
373{
374 *flags |= MS_RDONLY;
375 return 0;
376}
377
378
379static void squashfs_put_super(struct super_block *sb)
380{
381 if (sb->s_fs_info) {
382 struct squashfs_sb_info *sbi = sb->s_fs_info;
383 squashfs_cache_delete(sbi->block_cache);
384 squashfs_cache_delete(sbi->fragment_cache);
385 squashfs_cache_delete(sbi->read_page);
4c0f0bb2 386 squashfs_decompressor_free(sbi, sbi->stream);
0aa66619
PL
387 kfree(sbi->id_table);
388 kfree(sbi->fragment_index);
389 kfree(sbi->meta_index);
370ec3d1 390 kfree(sbi->inode_lookup_table);
4b5397dc 391 kfree(sbi->xattr_id_table);
0aa66619
PL
392 kfree(sb->s_fs_info);
393 sb->s_fs_info = NULL;
394 }
395}
396
397
003a3194
PL
398static struct dentry *squashfs_mount(struct file_system_type *fs_type,
399 int flags, const char *dev_name, void *data)
0aa66619 400{
152a0836 401 return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super);
0aa66619
PL
402}
403
404
405static struct kmem_cache *squashfs_inode_cachep;
406
407
408static void init_once(void *foo)
409{
410 struct squashfs_inode_info *ei = foo;
411
412 inode_init_once(&ei->vfs_inode);
413}
414
415
416static int __init init_inodecache(void)
417{
418 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
419 sizeof(struct squashfs_inode_info), 0,
420 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once);
421
422 return squashfs_inode_cachep ? 0 : -ENOMEM;
423}
424
425
426static void destroy_inodecache(void)
427{
8c0a8537
KS
428 /*
429 * Make sure all delayed rcu free inodes are flushed before we
430 * destroy cache.
431 */
432 rcu_barrier();
0aa66619
PL
433 kmem_cache_destroy(squashfs_inode_cachep);
434}
435
436
437static int __init init_squashfs_fs(void)
438{
439 int err = init_inodecache();
440
441 if (err)
442 return err;
443
444 err = register_filesystem(&squashfs_fs_type);
445 if (err) {
446 destroy_inodecache();
447 return err;
448 }
449
118e1ef6 450 printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) "
0aa66619
PL
451 "Phillip Lougher\n");
452
453 return 0;
454}
455
456
457static void __exit exit_squashfs_fs(void)
458{
459 unregister_filesystem(&squashfs_fs_type);
460 destroy_inodecache();
461}
462
463
464static struct inode *squashfs_alloc_inode(struct super_block *sb)
465{
466 struct squashfs_inode_info *ei =
467 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
468
469 return ei ? &ei->vfs_inode : NULL;
470}
471
472
fa0d7e3d 473static void squashfs_i_callback(struct rcu_head *head)
0aa66619 474{
fa0d7e3d 475 struct inode *inode = container_of(head, struct inode, i_rcu);
0aa66619
PL
476 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
477}
478
fa0d7e3d
NP
479static void squashfs_destroy_inode(struct inode *inode)
480{
481 call_rcu(&inode->i_rcu, squashfs_i_callback);
482}
483
0aa66619
PL
484
485static struct file_system_type squashfs_fs_type = {
486 .owner = THIS_MODULE,
487 .name = "squashfs",
152a0836 488 .mount = squashfs_mount,
0aa66619
PL
489 .kill_sb = kill_block_super,
490 .fs_flags = FS_REQUIRES_DEV
491};
3e64fe5b 492MODULE_ALIAS_FS("squashfs");
0aa66619 493
b87221de 494static const struct super_operations squashfs_super_ops = {
0aa66619
PL
495 .alloc_inode = squashfs_alloc_inode,
496 .destroy_inode = squashfs_destroy_inode,
497 .statfs = squashfs_statfs,
498 .put_super = squashfs_put_super,
499 .remount_fs = squashfs_remount
500};
501
502module_init(init_squashfs_fs);
503module_exit(exit_squashfs_fs);
504MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
d7f2ff67 505MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
0aa66619 506MODULE_LICENSE("GPL");