source: src/linux/universal/linux-4.9/fs/squashfs/super.c @ 31630

Last change on this file since 31630 was 31630, checked in by brainslayer, 4 months ago

new fs is compatible with standard squashfs, just smaller

File size: 13.7 KB
Line 
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        struct inode *root;
84        long long root_inode;
85        unsigned short flags;
86        unsigned int fragments;
87        u64 lookup_table_start, xattr_id_table_start, next_table;
88        int err;
89
90        TRACE("Entered squashfs_fill_superblock\n");
91
92        sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
93        if (sb->s_fs_info == NULL) {
94                ERROR("Failed to allocate squashfs_sb_info\n");
95                return -ENOMEM;
96        }
97        msblk = sb->s_fs_info;
98
99        msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
100        msblk->devblksize_log2 = ffz(~msblk->devblksize);
101
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 %pg\n",
127                                                sb->s_bdev);
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_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        /* Check block log for sanity */
162        msblk->block_log = le16_to_cpu(sblk->block_log);
163        if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
164                goto failed_mount;
165
166        /* Check that block_size and block_log match */
167        if (msblk->block_size != (1 << msblk->block_log))
168                goto failed_mount;
169
170        /* Check the root inode for sanity */
171        root_inode = le64_to_cpu(sblk->root_inode);
172        if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
173                goto failed_mount;
174
175        msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
176        msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
177        msblk->inodes = le32_to_cpu(sblk->inodes);
178        flags = le16_to_cpu(sblk->flags);
179
180        TRACE("Found valid superblock on %pg\n", sb->s_bdev);
181        TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
182                                ? "un" : "");
183        TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
184                                ? "un" : "");
185        TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
186        TRACE("Block size %d\n", msblk->block_size);
187        TRACE("Number of inodes %d\n", msblk->inodes);
188        TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments));
189        TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
190        TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
191        TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
192        TRACE("sblk->fragment_table_start %llx\n",
193                (u64) le64_to_cpu(sblk->fragment_table_start));
194        TRACE("sblk->id_table_start %llx\n",
195                (u64) le64_to_cpu(sblk->id_table_start));
196
197        sb->s_maxbytes = MAX_LFS_FILESIZE;
198        sb->s_flags |= MS_RDONLY;
199        sb->s_op = &squashfs_super_ops;
200
201        err = -ENOMEM;
202
203        msblk->block_cache = squashfs_cache_init("metadata",
204                        SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
205        if (msblk->block_cache == NULL)
206                goto failed_mount;
207
208        /* Allocate read_page block */
209        msblk->read_page = squashfs_cache_init("data",
210                squashfs_max_decompressors(), 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        msblk->stream = squashfs_decompressor_setup(sb, flags);
217        if (IS_ERR(msblk->stream)) {
218                err = PTR_ERR(msblk->stream);
219                msblk->stream = NULL;
220                goto failed_mount;
221        }
222
223        /* Handle xattrs */
224        sb->s_xattr = squashfs_xattr_handlers;
225        xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
226        if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
227                next_table = msblk->bytes_used;
228                goto allocate_id_index_table;
229        }
230
231        /* Allocate and read xattr id lookup table */
232        msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
233                xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
234        if (IS_ERR(msblk->xattr_id_table)) {
235                ERROR("unable to read xattr id index table\n");
236                err = PTR_ERR(msblk->xattr_id_table);
237                msblk->xattr_id_table = NULL;
238                if (err != -ENOTSUPP)
239                        goto failed_mount;
240        }
241        next_table = msblk->xattr_table;
242
243allocate_id_index_table:
244        /* Allocate and read id index table */
245        msblk->id_table = squashfs_read_id_index_table(sb,
246                le64_to_cpu(sblk->id_table_start), next_table,
247                le16_to_cpu(sblk->no_ids));
248        if (IS_ERR(msblk->id_table)) {
249                ERROR("unable to read id index table\n");
250                err = PTR_ERR(msblk->id_table);
251                msblk->id_table = NULL;
252                goto failed_mount;
253        }
254        next_table = le64_to_cpu(msblk->id_table[0]);
255
256        /* Handle inode lookup table */
257        lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
258        if (lookup_table_start == SQUASHFS_INVALID_BLK)
259                goto handle_fragments;
260
261        /* Allocate and read inode lookup table */
262        msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
263                lookup_table_start, next_table, msblk->inodes);
264        if (IS_ERR(msblk->inode_lookup_table)) {
265                ERROR("unable to read inode lookup table\n");
266                err = PTR_ERR(msblk->inode_lookup_table);
267                msblk->inode_lookup_table = NULL;
268                goto failed_mount;
269        }
270        next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
271
272        sb->s_export_op = &squashfs_export_ops;
273
274handle_fragments:
275        fragments = le32_to_cpu(sblk->fragments);
276        if (fragments == 0)
277                goto check_directory_table;
278
279        msblk->fragment_cache = squashfs_cache_init("fragment",
280                SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
281        if (msblk->fragment_cache == NULL) {
282                err = -ENOMEM;
283                goto failed_mount;
284        }
285
286        /* Allocate and read fragment index table */
287        msblk->fragment_index = squashfs_read_fragment_index_table(sb,
288                le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
289        if (IS_ERR(msblk->fragment_index)) {
290                ERROR("unable to read fragment index table\n");
291                err = PTR_ERR(msblk->fragment_index);
292                msblk->fragment_index = NULL;
293                goto failed_mount;
294        }
295        next_table = le64_to_cpu(msblk->fragment_index[0]);
296
297check_directory_table:
298        /* Sanity check directory_table */
299        if (msblk->directory_table > next_table) {
300                err = -EINVAL;
301                goto failed_mount;
302        }
303
304        /* Sanity check inode_table */
305        if (msblk->inode_table >= msblk->directory_table) {
306                err = -EINVAL;
307                goto failed_mount;
308        }
309
310        /* allocate root */
311        root = new_inode(sb);
312        if (!root) {
313                err = -ENOMEM;
314                goto failed_mount;
315        }
316
317        err = squashfs_read_inode(root, root_inode);
318        if (err) {
319                make_bad_inode(root);
320                iput(root);
321                goto failed_mount;
322        }
323        insert_inode_hash(root);
324
325        sb->s_root = d_make_root(root);
326        if (sb->s_root == NULL) {
327                ERROR("Root inode create failed\n");
328                err = -ENOMEM;
329                goto failed_mount;
330        }
331
332        TRACE("Leaving squashfs_fill_super\n");
333        kfree(sblk);
334        return 0;
335
336failed_mount:
337        squashfs_cache_delete(msblk->block_cache);
338        squashfs_cache_delete(msblk->fragment_cache);
339        squashfs_cache_delete(msblk->read_page);
340        squashfs_decompressor_destroy(msblk);
341        kfree(msblk->inode_lookup_table);
342        kfree(msblk->fragment_index);
343        kfree(msblk->id_table);
344        kfree(msblk->xattr_id_table);
345        kfree(sb->s_fs_info);
346        sb->s_fs_info = NULL;
347        kfree(sblk);
348        return err;
349}
350
351
352static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
353{
354        struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
355        u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
356
357        TRACE("Entered squashfs_statfs\n");
358
359        buf->f_type = SQUASHFS_MAGIC;
360        buf->f_bsize = msblk->block_size;
361        buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
362        buf->f_bfree = buf->f_bavail = 0;
363        buf->f_files = msblk->inodes;
364        buf->f_ffree = 0;
365        buf->f_namelen = SQUASHFS_NAME_LEN;
366        buf->f_fsid.val[0] = (u32)id;
367        buf->f_fsid.val[1] = (u32)(id >> 32);
368
369        return 0;
370}
371
372
373static int squashfs_remount(struct super_block *sb, int *flags, char *data)
374{
375        sync_filesystem(sb);
376        *flags |= MS_RDONLY;
377        return 0;
378}
379
380
381static void squashfs_put_super(struct super_block *sb)
382{
383        if (sb->s_fs_info) {
384                struct squashfs_sb_info *sbi = sb->s_fs_info;
385                squashfs_cache_delete(sbi->block_cache);
386                squashfs_cache_delete(sbi->fragment_cache);
387                squashfs_cache_delete(sbi->read_page);
388                squashfs_decompressor_destroy(sbi);
389                kfree(sbi->id_table);
390                kfree(sbi->fragment_index);
391                kfree(sbi->meta_index);
392                kfree(sbi->inode_lookup_table);
393                kfree(sbi->xattr_id_table);
394                kfree(sb->s_fs_info);
395                sb->s_fs_info = NULL;
396        }
397}
398
399
400static struct dentry *squashfs_mount(struct file_system_type *fs_type,
401                                int flags, const char *dev_name, void *data)
402{
403        return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super);
404}
405
406
407static struct kmem_cache *squashfs_inode_cachep;
408
409
410static void init_once(void *foo)
411{
412        struct squashfs_inode_info *ei = foo;
413
414        inode_init_once(&ei->vfs_inode);
415}
416
417
418static int __init init_inodecache(void)
419{
420        squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
421                sizeof(struct squashfs_inode_info), 0,
422                SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
423                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");
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