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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
31
32#include <linux/fs.h>
33#include <linux/vfs.h>
34#include <linux/slab.h>
35#include <linux/mutex.h>
36#include <linux/pagemap.h>
37#include <linux/init.h>
38#include <linux/module.h>
39#include <linux/magic.h>
40#include <linux/xattr.h>
41
42#include "squashfs_fs.h"
43#include "squashfs_fs_sb.h"
44#include "squashfs_fs_i.h"
45#include "squashfs.h"
46#include "decompressor.h"
47#include "xattr.h"
48
49static struct file_system_type squashfs_fs_type;
50static const struct super_operations squashfs_super_ops;
51
52static const struct squashfs_decompressor *supported_squashfs_filesystem(short
53	major, short minor, short id)
54{
55	const struct squashfs_decompressor *decompressor;
56
57	if (major < SQUASHFS_MAJOR) {
58		ERROR("Major/Minor mismatch, older Squashfs %d.%d "
59			"filesystems are unsupported\n", major, minor);
60		return NULL;
61	} else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
62		ERROR("Major/Minor mismatch, trying to mount newer "
63			"%d.%d filesystem\n", major, minor);
64		ERROR("Please update your kernel\n");
65		return NULL;
66	}
67
68	decompressor = squashfs_lookup_decompressor(id);
69	if (!decompressor->supported) {
70		ERROR("Filesystem uses \"%s\" compression. This is not "
71			"supported\n", decompressor->name);
72		return NULL;
73	}
74
75	return decompressor;
76}
77
78
79static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
80{
81	struct squashfs_sb_info *msblk;
82	struct squashfs_super_block *sblk = NULL;
83	char b[BDEVNAME_SIZE];
84	struct inode *root;
85	long long root_inode;
86	unsigned short flags;
87	unsigned int fragments;
88	u64 lookup_table_start, xattr_id_table_start, next_table;
89	int err;
90
91	TRACE("Entered squashfs_fill_superblock\n");
92
93	sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
94	if (sb->s_fs_info == NULL) {
95		ERROR("Failed to allocate squashfs_sb_info\n");
96		return -ENOMEM;
97	}
98	msblk = sb->s_fs_info;
99
100	msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
101	msblk->devblksize_log2 = ffz(~msblk->devblksize);
102
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	sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
113
114	if (IS_ERR(sblk)) {
115		ERROR("unable to read squashfs_super_block\n");
116		err = PTR_ERR(sblk);
117		sblk = NULL;
118		goto failed_mount;
119	}
120
121	err = -EINVAL;
122
123	/* Check it is a SQUASHFS superblock */
124	sb->s_magic = le32_to_cpu(sblk->s_magic);
125	if (sb->s_magic != SQUASHFS_MAGIC) {
126		if (!silent)
127			ERROR("Can't find a SQUASHFS superblock on %s\n",
128						bdevname(sb->s_bdev, b));
129		goto failed_mount;
130	}
131
132	/* Check the MAJOR & MINOR versions and lookup compression type */
133	msblk->decompressor = supported_squashfs_filesystem(
134			le16_to_cpu(sblk->s_major),
135			le16_to_cpu(sblk->s_minor),
136			le16_to_cpu(sblk->compression));
137	if (msblk->decompressor == NULL)
138		goto failed_mount;
139
140	/* Check the filesystem does not extend beyond the end of the
141	   block device */
142	msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
143	if (msblk->bytes_used < 0 || msblk->bytes_used >
144			i_size_read(sb->s_bdev->bd_inode))
145		goto failed_mount;
146
147	/* Check block size for sanity */
148	msblk->block_size = le32_to_cpu(sblk->block_size);
149	if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
150		goto failed_mount;
151
152	/*
153	 * Check the system page size is not larger than the filesystem
154	 * block size (by default 128K).  This is currently not supported.
155	 */
156	if (PAGE_CACHE_SIZE > msblk->block_size) {
157		ERROR("Page size > filesystem block size (%d).  This is "
158			"currently not supported!\n", msblk->block_size);
159		goto failed_mount;
160	}
161
162	/* Check block log for sanity */
163	msblk->block_log = le16_to_cpu(sblk->block_log);
164	if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
165		goto failed_mount;
166
167	/* Check that block_size and block_log match */
168	if (msblk->block_size != (1 << msblk->block_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",
211		squashfs_max_decompressors(), msblk->block_size);
212	if (msblk->read_page == NULL) {
213		ERROR("Failed to allocate read_page block\n");
214		goto failed_mount;
215	}
216
217	msblk->stream = squashfs_decompressor_setup(sb, flags);
218	if (IS_ERR(msblk->stream)) {
219		err = PTR_ERR(msblk->stream);
220		msblk->stream = NULL;
221		goto failed_mount;
222	}
223
224	/* Handle xattrs */
225	sb->s_xattr = squashfs_xattr_handlers;
226	xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
227	if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
228		next_table = msblk->bytes_used;
229		goto allocate_id_index_table;
230	}
231
232	/* Allocate and read xattr id lookup table */
233	msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
234		xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
235	if (IS_ERR(msblk->xattr_id_table)) {
236		ERROR("unable to read xattr id index table\n");
237		err = PTR_ERR(msblk->xattr_id_table);
238		msblk->xattr_id_table = NULL;
239		if (err != -ENOTSUPP)
240			goto failed_mount;
241	}
242	next_table = msblk->xattr_table;
243
244allocate_id_index_table:
245	/* Allocate and read id index table */
246	msblk->id_table = squashfs_read_id_index_table(sb,
247		le64_to_cpu(sblk->id_table_start), next_table,
248		le16_to_cpu(sblk->no_ids));
249	if (IS_ERR(msblk->id_table)) {
250		ERROR("unable to read id index table\n");
251		err = PTR_ERR(msblk->id_table);
252		msblk->id_table = NULL;
253		goto failed_mount;
254	}
255	next_table = le64_to_cpu(msblk->id_table[0]);
256
257	/* Handle inode lookup table */
258	lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
259	if (lookup_table_start == SQUASHFS_INVALID_BLK)
260		goto handle_fragments;
261
262	/* Allocate and read inode lookup table */
263	msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
264		lookup_table_start, next_table, msblk->inodes);
265	if (IS_ERR(msblk->inode_lookup_table)) {
266		ERROR("unable to read inode lookup table\n");
267		err = PTR_ERR(msblk->inode_lookup_table);
268		msblk->inode_lookup_table = NULL;
269		goto failed_mount;
270	}
271	next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
272
273	sb->s_export_op = &squashfs_export_ops;
274
275handle_fragments:
276	fragments = le32_to_cpu(sblk->fragments);
277	if (fragments == 0)
278		goto check_directory_table;
279
280	msblk->fragment_cache = squashfs_cache_init("fragment",
281		SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
282	if (msblk->fragment_cache == NULL) {
283		err = -ENOMEM;
284		goto failed_mount;
285	}
286
287	/* Allocate and read fragment index table */
288	msblk->fragment_index = squashfs_read_fragment_index_table(sb,
289		le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
290	if (IS_ERR(msblk->fragment_index)) {
291		ERROR("unable to read fragment index table\n");
292		err = PTR_ERR(msblk->fragment_index);
293		msblk->fragment_index = NULL;
294		goto failed_mount;
295	}
296	next_table = le64_to_cpu(msblk->fragment_index[0]);
297
298check_directory_table:
299	/* Sanity check directory_table */
300	if (msblk->directory_table > next_table) {
301		err = -EINVAL;
302		goto failed_mount;
303	}
304
305	/* Sanity check inode_table */
306	if (msblk->inode_table >= msblk->directory_table) {
307		err = -EINVAL;
308		goto failed_mount;
309	}
310
311	/* allocate root */
312	root = new_inode(sb);
313	if (!root) {
314		err = -ENOMEM;
315		goto failed_mount;
316	}
317
318	err = squashfs_read_inode(root, root_inode);
319	if (err) {
320		make_bad_inode(root);
321		iput(root);
322		goto failed_mount;
323	}
324	insert_inode_hash(root);
325
326	sb->s_root = d_make_root(root);
327	if (sb->s_root == NULL) {
328		ERROR("Root inode create failed\n");
329		err = -ENOMEM;
330		goto failed_mount;
331	}
332
333	TRACE("Leaving squashfs_fill_super\n");
334	kfree(sblk);
335	return 0;
336
337failed_mount:
338	squashfs_cache_delete(msblk->block_cache);
339	squashfs_cache_delete(msblk->fragment_cache);
340	squashfs_cache_delete(msblk->read_page);
341	squashfs_decompressor_destroy(msblk);
342	kfree(msblk->inode_lookup_table);
343	kfree(msblk->fragment_index);
344	kfree(msblk->id_table);
345	kfree(msblk->xattr_id_table);
346	kfree(sb->s_fs_info);
347	sb->s_fs_info = NULL;
348	kfree(sblk);
349	return err;
350}
351
352
353static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
354{
355	struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
356	u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
357
358	TRACE("Entered squashfs_statfs\n");
359
360	buf->f_type = SQUASHFS_MAGIC;
361	buf->f_bsize = msblk->block_size;
362	buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
363	buf->f_bfree = buf->f_bavail = 0;
364	buf->f_files = msblk->inodes;
365	buf->f_ffree = 0;
366	buf->f_namelen = SQUASHFS_NAME_LEN;
367	buf->f_fsid.val[0] = (u32)id;
368	buf->f_fsid.val[1] = (u32)(id >> 32);
369
370	return 0;
371}
372
373
374static int squashfs_remount(struct super_block *sb, int *flags, char *data)
375{
376	sync_filesystem(sb);
377	*flags |= MS_RDONLY;
378	return 0;
379}
380
381
382static void squashfs_put_super(struct super_block *sb)
383{
384	if (sb->s_fs_info) {
385		struct squashfs_sb_info *sbi = sb->s_fs_info;
386		squashfs_cache_delete(sbi->block_cache);
387		squashfs_cache_delete(sbi->fragment_cache);
388		squashfs_cache_delete(sbi->read_page);
389		squashfs_decompressor_destroy(sbi);
390		kfree(sbi->id_table);
391		kfree(sbi->fragment_index);
392		kfree(sbi->meta_index);
393		kfree(sbi->inode_lookup_table);
394		kfree(sbi->xattr_id_table);
395		kfree(sb->s_fs_info);
396		sb->s_fs_info = NULL;
397	}
398}
399
400
401static struct dentry *squashfs_mount(struct file_system_type *fs_type,
402				int flags, const char *dev_name, void *data)
403{
404	return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super);
405}
406
407
408static struct kmem_cache *squashfs_inode_cachep;
409
410
411static void init_once(void *foo)
412{
413	struct squashfs_inode_info *ei = foo;
414
415	inode_init_once(&ei->vfs_inode);
416}
417
418
419static int __init init_inodecache(void)
420{
421	squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
422		sizeof(struct squashfs_inode_info), 0,
423		SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once);
424
425	return squashfs_inode_cachep ? 0 : -ENOMEM;
426}
427
428
429static void destroy_inodecache(void)
430{
431	/*
432	 * Make sure all delayed rcu free inodes are flushed before we
433	 * destroy cache.
434	 */
435	rcu_barrier();
436	kmem_cache_destroy(squashfs_inode_cachep);
437}
438
439
440static int __init init_squashfs_fs(void)
441{
442	int err = init_inodecache();
443
444	if (err)
445		return err;
446
447	err = register_filesystem(&squashfs_fs_type);
448	if (err) {
449		destroy_inodecache();
450		return err;
451	}
452
453	pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
454
455	return 0;
456}
457
458
459static void __exit exit_squashfs_fs(void)
460{
461	unregister_filesystem(&squashfs_fs_type);
462	destroy_inodecache();
463}
464
465
466static struct inode *squashfs_alloc_inode(struct super_block *sb)
467{
468	struct squashfs_inode_info *ei =
469		kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
470
471	return ei ? &ei->vfs_inode : NULL;
472}
473
474
475static void squashfs_i_callback(struct rcu_head *head)
476{
477	struct inode *inode = container_of(head, struct inode, i_rcu);
478	kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
479}
480
481static void squashfs_destroy_inode(struct inode *inode)
482{
483	call_rcu(&inode->i_rcu, squashfs_i_callback);
484}
485
486
487static struct file_system_type squashfs_fs_type = {
488	.owner = THIS_MODULE,
489	.name = "squashfs",
490	.mount = squashfs_mount,
491	.kill_sb = kill_block_super,
492	.fs_flags = FS_REQUIRES_DEV
493};
494MODULE_ALIAS_FS("squashfs");
495
496static const struct super_operations squashfs_super_ops = {
497	.alloc_inode = squashfs_alloc_inode,
498	.destroy_inode = squashfs_destroy_inode,
499	.statfs = squashfs_statfs,
500	.put_super = squashfs_put_super,
501	.remount_fs = squashfs_remount
502};
503
504module_init(init_squashfs_fs);
505module_exit(exit_squashfs_fs);
506MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
507MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
508MODULE_LICENSE("GPL");
509