ecaa2f7bdb8f16ebac1a00896cc9d1a870351788
[linux-2.6.git] / fs / squashfs / super.c
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, SQUASHFS_DEVBLK_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         kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
468 }
469
470 static void squashfs_destroy_inode(struct inode *inode)
471 {
472         call_rcu(&inode->i_rcu, squashfs_i_callback);
473 }
474
475
476 static struct file_system_type squashfs_fs_type = {
477         .owner = THIS_MODULE,
478         .name = "squashfs",
479         .mount = squashfs_mount,
480         .kill_sb = kill_block_super,
481         .fs_flags = FS_REQUIRES_DEV
482 };
483
484 static const struct super_operations squashfs_super_ops = {
485         .alloc_inode = squashfs_alloc_inode,
486         .destroy_inode = squashfs_destroy_inode,
487         .statfs = squashfs_statfs,
488         .put_super = squashfs_put_super,
489         .remount_fs = squashfs_remount
490 };
491
492 module_init(init_squashfs_fs);
493 module_exit(exit_squashfs_fs);
494 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
495 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
496 MODULE_LICENSE("GPL");