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