xref: /openbmc/linux/fs/squashfs/super.c (revision df2634f43f5106947f3735a0b61a6527a4b278cd)
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/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;
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 	sblk = kzalloc(sizeof(*sblk), GFP_KERNEL);
99 	if (sblk == NULL) {
100 		ERROR("Failed to allocate squashfs_super_block\n");
101 		goto failure;
102 	}
103 
104 	msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE);
105 	msblk->devblksize_log2 = ffz(~msblk->devblksize);
106 
107 	mutex_init(&msblk->read_data_mutex);
108 	mutex_init(&msblk->meta_index_mutex);
109 
110 	/*
111 	 * msblk->bytes_used is checked in squashfs_read_table to ensure reads
112 	 * are not beyond filesystem end.  But as we're using
113 	 * squashfs_read_table here to read the superblock (including the value
114 	 * of bytes_used) we need to set it to an initial sensible dummy value
115 	 */
116 	msblk->bytes_used = sizeof(*sblk);
117 	err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk));
118 
119 	if (err < 0) {
120 		ERROR("unable to read squashfs_super_block\n");
121 		goto failed_mount;
122 	}
123 
124 	err = -EINVAL;
125 
126 	/* Check it is a SQUASHFS superblock */
127 	sb->s_magic = le32_to_cpu(sblk->s_magic);
128 	if (sb->s_magic != SQUASHFS_MAGIC) {
129 		if (!silent)
130 			ERROR("Can't find a SQUASHFS superblock on %s\n",
131 						bdevname(sb->s_bdev, b));
132 		goto failed_mount;
133 	}
134 
135 	/* Check the MAJOR & MINOR versions and lookup compression type */
136 	msblk->decompressor = supported_squashfs_filesystem(
137 			le16_to_cpu(sblk->s_major),
138 			le16_to_cpu(sblk->s_minor),
139 			le16_to_cpu(sblk->compression));
140 	if (msblk->decompressor == NULL)
141 		goto failed_mount;
142 
143 	/* Check the filesystem does not extend beyond the end of the
144 	   block device */
145 	msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
146 	if (msblk->bytes_used < 0 || msblk->bytes_used >
147 			i_size_read(sb->s_bdev->bd_inode))
148 		goto failed_mount;
149 
150 	/* Check block size for sanity */
151 	msblk->block_size = le32_to_cpu(sblk->block_size);
152 	if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
153 		goto failed_mount;
154 
155 	/*
156 	 * Check the system page size is not larger than the filesystem
157 	 * block size (by default 128K).  This is currently not supported.
158 	 */
159 	if (PAGE_CACHE_SIZE > msblk->block_size) {
160 		ERROR("Page size > filesystem block size (%d).  This is "
161 			"currently not supported!\n", msblk->block_size);
162 		goto failed_mount;
163 	}
164 
165 	msblk->block_log = le16_to_cpu(sblk->block_log);
166 	if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
167 		goto failed_mount;
168 
169 	/* Check the root inode for sanity */
170 	root_inode = le64_to_cpu(sblk->root_inode);
171 	if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
172 		goto failed_mount;
173 
174 	msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
175 	msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
176 	msblk->inodes = le32_to_cpu(sblk->inodes);
177 	flags = le16_to_cpu(sblk->flags);
178 
179 	TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b));
180 	TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
181 				? "un" : "");
182 	TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
183 				? "un" : "");
184 	TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
185 	TRACE("Block size %d\n", msblk->block_size);
186 	TRACE("Number of inodes %d\n", msblk->inodes);
187 	TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments));
188 	TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
189 	TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
190 	TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
191 	TRACE("sblk->fragment_table_start %llx\n",
192 		(u64) le64_to_cpu(sblk->fragment_table_start));
193 	TRACE("sblk->id_table_start %llx\n",
194 		(u64) le64_to_cpu(sblk->id_table_start));
195 
196 	sb->s_maxbytes = MAX_LFS_FILESIZE;
197 	sb->s_flags |= MS_RDONLY;
198 	sb->s_op = &squashfs_super_ops;
199 
200 	err = -ENOMEM;
201 
202 	msblk->stream = squashfs_decompressor_init(msblk);
203 	if (msblk->stream == NULL)
204 		goto failed_mount;
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", 1, msblk->block_size);
213 	if (msblk->read_page == NULL) {
214 		ERROR("Failed to allocate read_page block\n");
215 		goto failed_mount;
216 	}
217 
218 	/* Allocate and read id index table */
219 	msblk->id_table = squashfs_read_id_index_table(sb,
220 		le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids));
221 	if (IS_ERR(msblk->id_table)) {
222 		err = PTR_ERR(msblk->id_table);
223 		msblk->id_table = NULL;
224 		goto failed_mount;
225 	}
226 
227 	fragments = le32_to_cpu(sblk->fragments);
228 	if (fragments == 0)
229 		goto allocate_lookup_table;
230 
231 	msblk->fragment_cache = squashfs_cache_init("fragment",
232 		SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
233 	if (msblk->fragment_cache == NULL) {
234 		err = -ENOMEM;
235 		goto failed_mount;
236 	}
237 
238 	/* Allocate and read fragment index table */
239 	msblk->fragment_index = squashfs_read_fragment_index_table(sb,
240 		le64_to_cpu(sblk->fragment_table_start), fragments);
241 	if (IS_ERR(msblk->fragment_index)) {
242 		err = PTR_ERR(msblk->fragment_index);
243 		msblk->fragment_index = NULL;
244 		goto failed_mount;
245 	}
246 
247 allocate_lookup_table:
248 	lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
249 	if (lookup_table_start == SQUASHFS_INVALID_BLK)
250 		goto allocate_xattr_table;
251 
252 	/* Allocate and read inode lookup table */
253 	msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
254 		lookup_table_start, msblk->inodes);
255 	if (IS_ERR(msblk->inode_lookup_table)) {
256 		err = PTR_ERR(msblk->inode_lookup_table);
257 		msblk->inode_lookup_table = NULL;
258 		goto failed_mount;
259 	}
260 
261 	sb->s_export_op = &squashfs_export_ops;
262 
263 allocate_xattr_table:
264 	sb->s_xattr = squashfs_xattr_handlers;
265 	xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
266 	if (xattr_id_table_start == SQUASHFS_INVALID_BLK)
267 		goto allocate_root;
268 
269 	/* Allocate and read xattr id lookup table */
270 	msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
271 		xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
272 	if (IS_ERR(msblk->xattr_id_table)) {
273 		err = PTR_ERR(msblk->xattr_id_table);
274 		msblk->xattr_id_table = NULL;
275 		if (err != -ENOTSUPP)
276 			goto failed_mount;
277 	}
278 allocate_root:
279 	root = new_inode(sb);
280 	if (!root) {
281 		err = -ENOMEM;
282 		goto failed_mount;
283 	}
284 
285 	err = squashfs_read_inode(root, root_inode);
286 	if (err) {
287 		make_bad_inode(root);
288 		iput(root);
289 		goto failed_mount;
290 	}
291 	insert_inode_hash(root);
292 
293 	sb->s_root = d_alloc_root(root);
294 	if (sb->s_root == NULL) {
295 		ERROR("Root inode create failed\n");
296 		err = -ENOMEM;
297 		iput(root);
298 		goto failed_mount;
299 	}
300 
301 	TRACE("Leaving squashfs_fill_super\n");
302 	kfree(sblk);
303 	return 0;
304 
305 failed_mount:
306 	squashfs_cache_delete(msblk->block_cache);
307 	squashfs_cache_delete(msblk->fragment_cache);
308 	squashfs_cache_delete(msblk->read_page);
309 	squashfs_decompressor_free(msblk, msblk->stream);
310 	kfree(msblk->inode_lookup_table);
311 	kfree(msblk->fragment_index);
312 	kfree(msblk->id_table);
313 	kfree(msblk->xattr_id_table);
314 	kfree(sb->s_fs_info);
315 	sb->s_fs_info = NULL;
316 	kfree(sblk);
317 	return err;
318 
319 failure:
320 	kfree(sb->s_fs_info);
321 	sb->s_fs_info = NULL;
322 	return -ENOMEM;
323 }
324 
325 
326 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
327 {
328 	struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
329 	u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
330 
331 	TRACE("Entered squashfs_statfs\n");
332 
333 	buf->f_type = SQUASHFS_MAGIC;
334 	buf->f_bsize = msblk->block_size;
335 	buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
336 	buf->f_bfree = buf->f_bavail = 0;
337 	buf->f_files = msblk->inodes;
338 	buf->f_ffree = 0;
339 	buf->f_namelen = SQUASHFS_NAME_LEN;
340 	buf->f_fsid.val[0] = (u32)id;
341 	buf->f_fsid.val[1] = (u32)(id >> 32);
342 
343 	return 0;
344 }
345 
346 
347 static int squashfs_remount(struct super_block *sb, int *flags, char *data)
348 {
349 	*flags |= MS_RDONLY;
350 	return 0;
351 }
352 
353 
354 static void squashfs_put_super(struct super_block *sb)
355 {
356 	if (sb->s_fs_info) {
357 		struct squashfs_sb_info *sbi = sb->s_fs_info;
358 		squashfs_cache_delete(sbi->block_cache);
359 		squashfs_cache_delete(sbi->fragment_cache);
360 		squashfs_cache_delete(sbi->read_page);
361 		squashfs_decompressor_free(sbi, sbi->stream);
362 		kfree(sbi->id_table);
363 		kfree(sbi->fragment_index);
364 		kfree(sbi->meta_index);
365 		kfree(sbi->inode_lookup_table);
366 		kfree(sbi->xattr_id_table);
367 		kfree(sb->s_fs_info);
368 		sb->s_fs_info = NULL;
369 	}
370 }
371 
372 
373 static struct dentry *squashfs_mount(struct file_system_type *fs_type, int flags,
374 				const char *dev_name, void *data)
375 {
376 	return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super);
377 }
378 
379 
380 static struct kmem_cache *squashfs_inode_cachep;
381 
382 
383 static void init_once(void *foo)
384 {
385 	struct squashfs_inode_info *ei = foo;
386 
387 	inode_init_once(&ei->vfs_inode);
388 }
389 
390 
391 static int __init init_inodecache(void)
392 {
393 	squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
394 		sizeof(struct squashfs_inode_info), 0,
395 		SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once);
396 
397 	return squashfs_inode_cachep ? 0 : -ENOMEM;
398 }
399 
400 
401 static void destroy_inodecache(void)
402 {
403 	kmem_cache_destroy(squashfs_inode_cachep);
404 }
405 
406 
407 static int __init init_squashfs_fs(void)
408 {
409 	int err = init_inodecache();
410 
411 	if (err)
412 		return err;
413 
414 	err = register_filesystem(&squashfs_fs_type);
415 	if (err) {
416 		destroy_inodecache();
417 		return err;
418 	}
419 
420 	printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) "
421 		"Phillip Lougher\n");
422 
423 	return 0;
424 }
425 
426 
427 static void __exit exit_squashfs_fs(void)
428 {
429 	unregister_filesystem(&squashfs_fs_type);
430 	destroy_inodecache();
431 }
432 
433 
434 static struct inode *squashfs_alloc_inode(struct super_block *sb)
435 {
436 	struct squashfs_inode_info *ei =
437 		kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
438 
439 	return ei ? &ei->vfs_inode : NULL;
440 }
441 
442 
443 static void squashfs_i_callback(struct rcu_head *head)
444 {
445 	struct inode *inode = container_of(head, struct inode, i_rcu);
446 	INIT_LIST_HEAD(&inode->i_dentry);
447 	kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
448 }
449 
450 static void squashfs_destroy_inode(struct inode *inode)
451 {
452 	call_rcu(&inode->i_rcu, squashfs_i_callback);
453 }
454 
455 
456 static struct file_system_type squashfs_fs_type = {
457 	.owner = THIS_MODULE,
458 	.name = "squashfs",
459 	.mount = squashfs_mount,
460 	.kill_sb = kill_block_super,
461 	.fs_flags = FS_REQUIRES_DEV
462 };
463 
464 static const struct super_operations squashfs_super_ops = {
465 	.alloc_inode = squashfs_alloc_inode,
466 	.destroy_inode = squashfs_destroy_inode,
467 	.statfs = squashfs_statfs,
468 	.put_super = squashfs_put_super,
469 	.remount_fs = squashfs_remount
470 };
471 
472 module_init(init_squashfs_fs);
473 module_exit(exit_squashfs_fs);
474 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
475 MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>");
476 MODULE_LICENSE("GPL");
477