Squashfs: factor out remaining zlib dependencies into separate wrapper file
[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@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/smp_lock.h>
34 #include <linux/mutex.h>
35 #include <linux/pagemap.h>
36 #include <linux/init.h>
37 #include <linux/module.h>
38 #include <linux/magic.h>
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 const 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 = squashfs_zlib_init();
90         if (msblk->stream == NULL)
91                 goto failure;
92
93         sblk = kzalloc(sizeof(*sblk), GFP_KERNEL);
94         if (sblk == NULL) {
95                 ERROR("Failed to allocate squashfs_super_block\n");
96                 goto failure;
97         }
98
99         msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE);
100         msblk->devblksize_log2 = ffz(~msblk->devblksize);
101
102         mutex_init(&msblk->read_data_mutex);
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         err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk));
113
114         if (err < 0) {
115                 ERROR("unable to read squashfs_super_block\n");
116                 goto failed_mount;
117         }
118
119         /* Check it is a SQUASHFS superblock */
120         sb->s_magic = le32_to_cpu(sblk->s_magic);
121         if (sb->s_magic != SQUASHFS_MAGIC) {
122                 if (!silent)
123                         ERROR("Can't find a SQUASHFS superblock on %s\n",
124                                                 bdevname(sb->s_bdev, b));
125                 err = -EINVAL;
126                 goto failed_mount;
127         }
128
129         /* Check the MAJOR & MINOR versions and compression type */
130         err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major),
131                         le16_to_cpu(sblk->s_minor),
132                         le16_to_cpu(sblk->compression));
133         if (err < 0)
134                 goto failed_mount;
135
136         err = -EINVAL;
137
138         /*
139          * Check if there's xattrs in the filesystem.  These are not
140          * supported in this version, so warn that they will be ignored.
141          */
142         if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK)
143                 ERROR("Xattrs in filesystem, these will be ignored\n");
144
145         /* Check the filesystem does not extend beyond the end of the
146            block device */
147         msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
148         if (msblk->bytes_used < 0 || msblk->bytes_used >
149                         i_size_read(sb->s_bdev->bd_inode))
150                 goto failed_mount;
151
152         /* Check block size for sanity */
153         msblk->block_size = le32_to_cpu(sblk->block_size);
154         if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
155                 goto failed_mount;
156
157         /*
158          * Check the system page size is not larger than the filesystem
159          * block size (by default 128K).  This is currently not supported.
160          */
161         if (PAGE_CACHE_SIZE > msblk->block_size) {
162                 ERROR("Page size > filesystem block size (%d).  This is "
163                         "currently not supported!\n", msblk->block_size);
164                 goto failed_mount;
165         }
166
167         msblk->block_log = le16_to_cpu(sblk->block_log);
168         if (msblk->block_log > SQUASHFS_FILE_MAX_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         flags = le16_to_cpu(sblk->flags);
180
181         TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b));
182         TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
183                                 ? "un" : "");
184         TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
185                                 ? "un" : "");
186         TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
187         TRACE("Block size %d\n", msblk->block_size);
188         TRACE("Number of inodes %d\n", msblk->inodes);
189         TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments));
190         TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
191         TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
192         TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
193         TRACE("sblk->fragment_table_start %llx\n",
194                 (u64) le64_to_cpu(sblk->fragment_table_start));
195         TRACE("sblk->id_table_start %llx\n",
196                 (u64) le64_to_cpu(sblk->id_table_start));
197
198         sb->s_maxbytes = MAX_LFS_FILESIZE;
199         sb->s_flags |= MS_RDONLY;
200         sb->s_op = &squashfs_super_ops;
201
202         err = -ENOMEM;
203
204         msblk->block_cache = squashfs_cache_init("metadata",
205                         SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
206         if (msblk->block_cache == NULL)
207                 goto failed_mount;
208
209         /* Allocate read_page block */
210         msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size);
211         if (msblk->read_page == NULL) {
212                 ERROR("Failed to allocate read_page block\n");
213                 goto failed_mount;
214         }
215
216         /* Allocate and read id index table */
217         msblk->id_table = squashfs_read_id_index_table(sb,
218                 le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids));
219         if (IS_ERR(msblk->id_table)) {
220                 err = PTR_ERR(msblk->id_table);
221                 msblk->id_table = NULL;
222                 goto failed_mount;
223         }
224
225         fragments = le32_to_cpu(sblk->fragments);
226         if (fragments == 0)
227                 goto allocate_lookup_table;
228
229         msblk->fragment_cache = squashfs_cache_init("fragment",
230                 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
231         if (msblk->fragment_cache == NULL) {
232                 err = -ENOMEM;
233                 goto failed_mount;
234         }
235
236         /* Allocate and read fragment index table */
237         msblk->fragment_index = squashfs_read_fragment_index_table(sb,
238                 le64_to_cpu(sblk->fragment_table_start), fragments);
239         if (IS_ERR(msblk->fragment_index)) {
240                 err = PTR_ERR(msblk->fragment_index);
241                 msblk->fragment_index = NULL;
242                 goto failed_mount;
243         }
244
245 allocate_lookup_table:
246         lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
247         if (lookup_table_start == SQUASHFS_INVALID_BLK)
248                 goto allocate_root;
249
250         /* Allocate and read inode lookup table */
251         msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
252                 lookup_table_start, msblk->inodes);
253         if (IS_ERR(msblk->inode_lookup_table)) {
254                 err = PTR_ERR(msblk->inode_lookup_table);
255                 msblk->inode_lookup_table = NULL;
256                 goto failed_mount;
257         }
258
259         sb->s_export_op = &squashfs_export_ops;
260
261 allocate_root:
262         root = new_inode(sb);
263         if (!root) {
264                 err = -ENOMEM;
265                 goto failed_mount;
266         }
267
268         err = squashfs_read_inode(root, root_inode);
269         if (err) {
270                 iget_failed(root);
271                 goto failed_mount;
272         }
273         insert_inode_hash(root);
274
275         sb->s_root = d_alloc_root(root);
276         if (sb->s_root == NULL) {
277                 ERROR("Root inode create failed\n");
278                 err = -ENOMEM;
279                 iput(root);
280                 goto failed_mount;
281         }
282
283         TRACE("Leaving squashfs_fill_super\n");
284         kfree(sblk);
285         return 0;
286
287 failed_mount:
288         squashfs_cache_delete(msblk->block_cache);
289         squashfs_cache_delete(msblk->fragment_cache);
290         squashfs_cache_delete(msblk->read_page);
291         squashfs_zlib_free(msblk->stream);
292         kfree(msblk->inode_lookup_table);
293         kfree(msblk->fragment_index);
294         kfree(msblk->id_table);
295         kfree(sb->s_fs_info);
296         sb->s_fs_info = NULL;
297         kfree(sblk);
298         return err;
299
300 failure:
301         squashfs_zlib_free(msblk->stream);
302         kfree(sb->s_fs_info);
303         sb->s_fs_info = NULL;
304         return -ENOMEM;
305 }
306
307
308 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
309 {
310         struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
311         u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
312
313         TRACE("Entered squashfs_statfs\n");
314
315         buf->f_type = SQUASHFS_MAGIC;
316         buf->f_bsize = msblk->block_size;
317         buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
318         buf->f_bfree = buf->f_bavail = 0;
319         buf->f_files = msblk->inodes;
320         buf->f_ffree = 0;
321         buf->f_namelen = SQUASHFS_NAME_LEN;
322         buf->f_fsid.val[0] = (u32)id;
323         buf->f_fsid.val[1] = (u32)(id >> 32);
324
325         return 0;
326 }
327
328
329 static int squashfs_remount(struct super_block *sb, int *flags, char *data)
330 {
331         *flags |= MS_RDONLY;
332         return 0;
333 }
334
335
336 static void squashfs_put_super(struct super_block *sb)
337 {
338         lock_kernel();
339
340         if (sb->s_fs_info) {
341                 struct squashfs_sb_info *sbi = sb->s_fs_info;
342                 squashfs_cache_delete(sbi->block_cache);
343                 squashfs_cache_delete(sbi->fragment_cache);
344                 squashfs_cache_delete(sbi->read_page);
345                 squashfs_zlib_free(sbi->stream);
346                 kfree(sbi->id_table);
347                 kfree(sbi->fragment_index);
348                 kfree(sbi->meta_index);
349                 kfree(sb->s_fs_info);
350                 sb->s_fs_info = NULL;
351         }
352
353         unlock_kernel();
354 }
355
356
357 static int squashfs_get_sb(struct file_system_type *fs_type, int flags,
358                                 const char *dev_name, void *data,
359                                 struct vfsmount *mnt)
360 {
361         return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super,
362                                 mnt);
363 }
364
365
366 static struct kmem_cache *squashfs_inode_cachep;
367
368
369 static void init_once(void *foo)
370 {
371         struct squashfs_inode_info *ei = foo;
372
373         inode_init_once(&ei->vfs_inode);
374 }
375
376
377 static int __init init_inodecache(void)
378 {
379         squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
380                 sizeof(struct squashfs_inode_info), 0,
381                 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once);
382
383         return squashfs_inode_cachep ? 0 : -ENOMEM;
384 }
385
386
387 static void destroy_inodecache(void)
388 {
389         kmem_cache_destroy(squashfs_inode_cachep);
390 }
391
392
393 static int __init init_squashfs_fs(void)
394 {
395         int err = init_inodecache();
396
397         if (err)
398                 return err;
399
400         err = register_filesystem(&squashfs_fs_type);
401         if (err) {
402                 destroy_inodecache();
403                 return err;
404         }
405
406         printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) "
407                 "Phillip Lougher\n");
408
409         return 0;
410 }
411
412
413 static void __exit exit_squashfs_fs(void)
414 {
415         unregister_filesystem(&squashfs_fs_type);
416         destroy_inodecache();
417 }
418
419
420 static struct inode *squashfs_alloc_inode(struct super_block *sb)
421 {
422         struct squashfs_inode_info *ei =
423                 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
424
425         return ei ? &ei->vfs_inode : NULL;
426 }
427
428
429 static void squashfs_destroy_inode(struct inode *inode)
430 {
431         kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
432 }
433
434
435 static struct file_system_type squashfs_fs_type = {
436         .owner = THIS_MODULE,
437         .name = "squashfs",
438         .get_sb = squashfs_get_sb,
439         .kill_sb = kill_block_super,
440         .fs_flags = FS_REQUIRES_DEV
441 };
442
443 static const struct super_operations squashfs_super_ops = {
444         .alloc_inode = squashfs_alloc_inode,
445         .destroy_inode = squashfs_destroy_inode,
446         .statfs = squashfs_statfs,
447         .put_super = squashfs_put_super,
448         .remount_fs = squashfs_remount
449 };
450
451 module_init(init_squashfs_fs);
452 module_exit(exit_squashfs_fs);
453 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
454 MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>");
455 MODULE_LICENSE("GPL");