1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Squashfs - a compressed read only filesystem for Linux
5 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
6 * Phillip Lougher <phillip@squashfs.org.uk>
12 * This file implements code to read the superblock, read and initialise
13 * in-memory structures at mount time, and all the VFS glue code to register
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 #include <linux/blkdev.h>
21 #include <linux/fs_context.h>
22 #include <linux/fs_parser.h>
23 #include <linux/vfs.h>
24 #include <linux/slab.h>
25 #include <linux/mutex.h>
26 #include <linux/seq_file.h>
27 #include <linux/pagemap.h>
28 #include <linux/init.h>
29 #include <linux/module.h>
30 #include <linux/magic.h>
31 #include <linux/xattr.h>
33 #include "squashfs_fs.h"
34 #include "squashfs_fs_sb.h"
35 #include "squashfs_fs_i.h"
37 #include "decompressor.h"
40 static struct file_system_type squashfs_fs_type;
41 static const struct super_operations squashfs_super_ops;
53 struct squashfs_mount_opts {
54 enum Opt_errors errors;
55 const struct squashfs_decompressor_thread_ops *thread_ops;
59 static const struct constant_table squashfs_param_errors[] = {
60 {"continue", Opt_errors_continue },
61 {"panic", Opt_errors_panic },
65 static const struct fs_parameter_spec squashfs_fs_parameters[] = {
66 fsparam_enum("errors", Opt_errors, squashfs_param_errors),
67 fsparam_string("threads", Opt_threads),
72 static int squashfs_parse_param_threads_str(const char *str, struct squashfs_mount_opts *opts)
74 #ifdef CONFIG_SQUASHFS_CHOICE_DECOMP_BY_MOUNT
75 if (strcmp(str, "single") == 0) {
76 opts->thread_ops = &squashfs_decompressor_single;
79 if (strcmp(str, "multi") == 0) {
80 opts->thread_ops = &squashfs_decompressor_multi;
83 if (strcmp(str, "percpu") == 0) {
84 opts->thread_ops = &squashfs_decompressor_percpu;
91 static int squashfs_parse_param_threads_num(const char *str, struct squashfs_mount_opts *opts)
93 #ifdef CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS
97 ret = kstrtoul(str, 0, &num);
101 opts->thread_ops = &squashfs_decompressor_multi;
102 if (num > opts->thread_ops->max_decompressors())
104 opts->thread_num = (int)num;
107 #ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
109 opts->thread_ops = &squashfs_decompressor_single;
110 opts->thread_num = 1;
114 #endif /* !CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS */
118 static int squashfs_parse_param_threads(const char *str, struct squashfs_mount_opts *opts)
120 int ret = squashfs_parse_param_threads_str(str, opts);
124 return squashfs_parse_param_threads_num(str, opts);
127 static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
129 struct squashfs_mount_opts *opts = fc->fs_private;
130 struct fs_parse_result result;
133 opt = fs_parse(fc, squashfs_fs_parameters, param, &result);
139 opts->errors = result.uint_32;
142 if (squashfs_parse_param_threads(param->string, opts) != 0)
152 static const struct squashfs_decompressor *supported_squashfs_filesystem(
153 struct fs_context *fc,
154 short major, short minor, short id)
156 const struct squashfs_decompressor *decompressor;
158 if (major < SQUASHFS_MAJOR) {
159 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
160 "filesystems are unsupported", major, minor);
162 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
163 errorf(fc, "Major/Minor mismatch, trying to mount newer "
164 "%d.%d filesystem", major, minor);
165 errorf(fc, "Please update your kernel");
169 decompressor = squashfs_lookup_decompressor(id);
170 if (!decompressor->supported) {
171 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
180 static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
182 struct squashfs_mount_opts *opts = fc->fs_private;
183 struct squashfs_sb_info *msblk;
184 struct squashfs_super_block *sblk = NULL;
186 long long root_inode;
187 unsigned short flags;
188 unsigned int fragments;
189 u64 lookup_table_start, xattr_id_table_start, next_table;
192 TRACE("Entered squashfs_fill_superblock\n");
194 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
195 if (sb->s_fs_info == NULL) {
196 ERROR("Failed to allocate squashfs_sb_info\n");
199 msblk = sb->s_fs_info;
200 msblk->thread_ops = opts->thread_ops;
202 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
204 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
205 msblk->devblksize_log2 = ffz(~msblk->devblksize);
207 mutex_init(&msblk->meta_index_mutex);
210 * msblk->bytes_used is checked in squashfs_read_table to ensure reads
211 * are not beyond filesystem end. But as we're using
212 * squashfs_read_table here to read the superblock (including the value
213 * of bytes_used) we need to set it to an initial sensible dummy value
215 msblk->bytes_used = sizeof(*sblk);
216 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
219 errorf(fc, "unable to read squashfs_super_block");
227 /* Check it is a SQUASHFS superblock */
228 sb->s_magic = le32_to_cpu(sblk->s_magic);
229 if (sb->s_magic != SQUASHFS_MAGIC) {
230 if (!(fc->sb_flags & SB_SILENT))
231 errorf(fc, "Can't find a SQUASHFS superblock on %pg",
236 if (opts->thread_num == 0) {
237 msblk->max_thread_num = msblk->thread_ops->max_decompressors();
239 msblk->max_thread_num = opts->thread_num;
242 /* Check the MAJOR & MINOR versions and lookup compression type */
243 msblk->decompressor = supported_squashfs_filesystem(
245 le16_to_cpu(sblk->s_major),
246 le16_to_cpu(sblk->s_minor),
247 le16_to_cpu(sblk->compression));
248 if (msblk->decompressor == NULL)
251 /* Check the filesystem does not extend beyond the end of the
253 msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
254 if (msblk->bytes_used < 0 ||
255 msblk->bytes_used > bdev_nr_bytes(sb->s_bdev))
258 /* Check block size for sanity */
259 msblk->block_size = le32_to_cpu(sblk->block_size);
260 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
264 * Check the system page size is not larger than the filesystem
265 * block size (by default 128K). This is currently not supported.
267 if (PAGE_SIZE > msblk->block_size) {
268 errorf(fc, "Page size > filesystem block size (%d). This is "
269 "currently not supported!", msblk->block_size);
273 /* Check block log for sanity */
274 msblk->block_log = le16_to_cpu(sblk->block_log);
275 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
278 /* Check that block_size and block_log match */
279 if (msblk->block_size != (1 << msblk->block_log))
282 /* Check the root inode for sanity */
283 root_inode = le64_to_cpu(sblk->root_inode);
284 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
287 msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
288 msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
289 msblk->inodes = le32_to_cpu(sblk->inodes);
290 msblk->fragments = le32_to_cpu(sblk->fragments);
291 msblk->ids = le16_to_cpu(sblk->no_ids);
292 flags = le16_to_cpu(sblk->flags);
294 TRACE("Found valid superblock on %pg\n", sb->s_bdev);
295 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
297 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
299 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
300 TRACE("Block size %d\n", msblk->block_size);
301 TRACE("Number of inodes %d\n", msblk->inodes);
302 TRACE("Number of fragments %d\n", msblk->fragments);
303 TRACE("Number of ids %d\n", msblk->ids);
304 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
305 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
306 TRACE("sblk->fragment_table_start %llx\n",
307 (u64) le64_to_cpu(sblk->fragment_table_start));
308 TRACE("sblk->id_table_start %llx\n",
309 (u64) le64_to_cpu(sblk->id_table_start));
311 sb->s_maxbytes = MAX_LFS_FILESIZE;
313 sb->s_time_max = U32_MAX;
314 sb->s_flags |= SB_RDONLY;
315 sb->s_op = &squashfs_super_ops;
319 msblk->block_cache = squashfs_cache_init("metadata",
320 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
321 if (msblk->block_cache == NULL)
324 /* Allocate read_page block */
325 msblk->read_page = squashfs_cache_init("data",
326 msblk->max_thread_num, msblk->block_size);
327 if (msblk->read_page == NULL) {
328 errorf(fc, "Failed to allocate read_page block");
332 msblk->stream = squashfs_decompressor_setup(sb, flags);
333 if (IS_ERR(msblk->stream)) {
334 err = PTR_ERR(msblk->stream);
335 msblk->stream = NULL;
340 sb->s_xattr = squashfs_xattr_handlers;
341 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
342 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
343 next_table = msblk->bytes_used;
344 goto allocate_id_index_table;
347 /* Allocate and read xattr id lookup table */
348 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
349 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
350 if (IS_ERR(msblk->xattr_id_table)) {
351 errorf(fc, "unable to read xattr id index table");
352 err = PTR_ERR(msblk->xattr_id_table);
353 msblk->xattr_id_table = NULL;
354 if (err != -ENOTSUPP)
357 next_table = msblk->xattr_table;
359 allocate_id_index_table:
360 /* Allocate and read id index table */
361 msblk->id_table = squashfs_read_id_index_table(sb,
362 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
363 if (IS_ERR(msblk->id_table)) {
364 errorf(fc, "unable to read id index table");
365 err = PTR_ERR(msblk->id_table);
366 msblk->id_table = NULL;
369 next_table = le64_to_cpu(msblk->id_table[0]);
371 /* Handle inode lookup table */
372 lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
373 if (lookup_table_start == SQUASHFS_INVALID_BLK)
374 goto handle_fragments;
376 /* Allocate and read inode lookup table */
377 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
378 lookup_table_start, next_table, msblk->inodes);
379 if (IS_ERR(msblk->inode_lookup_table)) {
380 errorf(fc, "unable to read inode lookup table");
381 err = PTR_ERR(msblk->inode_lookup_table);
382 msblk->inode_lookup_table = NULL;
385 next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
387 sb->s_export_op = &squashfs_export_ops;
390 fragments = msblk->fragments;
392 goto check_directory_table;
394 msblk->fragment_cache = squashfs_cache_init("fragment",
395 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
396 if (msblk->fragment_cache == NULL) {
401 /* Allocate and read fragment index table */
402 msblk->fragment_index = squashfs_read_fragment_index_table(sb,
403 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
404 if (IS_ERR(msblk->fragment_index)) {
405 errorf(fc, "unable to read fragment index table");
406 err = PTR_ERR(msblk->fragment_index);
407 msblk->fragment_index = NULL;
410 next_table = le64_to_cpu(msblk->fragment_index[0]);
412 check_directory_table:
413 /* Sanity check directory_table */
414 if (msblk->directory_table > next_table) {
419 /* Sanity check inode_table */
420 if (msblk->inode_table >= msblk->directory_table) {
426 root = new_inode(sb);
432 err = squashfs_read_inode(root, root_inode);
434 make_bad_inode(root);
438 insert_inode_hash(root);
440 sb->s_root = d_make_root(root);
441 if (sb->s_root == NULL) {
442 ERROR("Root inode create failed\n");
447 TRACE("Leaving squashfs_fill_super\n");
452 errorf(fc, "squashfs image failed sanity check");
454 squashfs_cache_delete(msblk->block_cache);
455 squashfs_cache_delete(msblk->fragment_cache);
456 squashfs_cache_delete(msblk->read_page);
457 msblk->thread_ops->destroy(msblk);
458 kfree(msblk->inode_lookup_table);
459 kfree(msblk->fragment_index);
460 kfree(msblk->id_table);
461 kfree(msblk->xattr_id_table);
462 kfree(sb->s_fs_info);
463 sb->s_fs_info = NULL;
468 static int squashfs_get_tree(struct fs_context *fc)
470 return get_tree_bdev(fc, squashfs_fill_super);
473 static int squashfs_reconfigure(struct fs_context *fc)
475 struct super_block *sb = fc->root->d_sb;
476 struct squashfs_sb_info *msblk = sb->s_fs_info;
477 struct squashfs_mount_opts *opts = fc->fs_private;
479 sync_filesystem(fc->root->d_sb);
480 fc->sb_flags |= SB_RDONLY;
482 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
487 static void squashfs_free_fs_context(struct fs_context *fc)
489 kfree(fc->fs_private);
492 static const struct fs_context_operations squashfs_context_ops = {
493 .get_tree = squashfs_get_tree,
494 .free = squashfs_free_fs_context,
495 .parse_param = squashfs_parse_param,
496 .reconfigure = squashfs_reconfigure,
499 static int squashfs_show_options(struct seq_file *s, struct dentry *root)
501 struct super_block *sb = root->d_sb;
502 struct squashfs_sb_info *msblk = sb->s_fs_info;
504 if (msblk->panic_on_errors)
505 seq_puts(s, ",errors=panic");
507 seq_puts(s, ",errors=continue");
509 #ifdef CONFIG_SQUASHFS_CHOICE_DECOMP_BY_MOUNT
510 if (msblk->thread_ops == &squashfs_decompressor_single) {
511 seq_puts(s, ",threads=single");
514 if (msblk->thread_ops == &squashfs_decompressor_percpu) {
515 seq_puts(s, ",threads=percpu");
519 #ifdef CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS
520 seq_printf(s, ",threads=%d", msblk->max_thread_num);
525 static int squashfs_init_fs_context(struct fs_context *fc)
527 struct squashfs_mount_opts *opts;
529 opts = kzalloc(sizeof(*opts), GFP_KERNEL);
533 #ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
534 opts->thread_ops = &squashfs_decompressor_single;
535 #elif defined(CONFIG_SQUASHFS_DECOMP_MULTI)
536 opts->thread_ops = &squashfs_decompressor_multi;
537 #elif defined(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU)
538 opts->thread_ops = &squashfs_decompressor_percpu;
540 #error "fail: unknown squashfs decompression thread mode?"
542 opts->thread_num = 0;
543 fc->fs_private = opts;
544 fc->ops = &squashfs_context_ops;
548 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
550 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
551 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
553 TRACE("Entered squashfs_statfs\n");
555 buf->f_type = SQUASHFS_MAGIC;
556 buf->f_bsize = msblk->block_size;
557 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
558 buf->f_bfree = buf->f_bavail = 0;
559 buf->f_files = msblk->inodes;
561 buf->f_namelen = SQUASHFS_NAME_LEN;
562 buf->f_fsid = u64_to_fsid(id);
568 static void squashfs_put_super(struct super_block *sb)
571 struct squashfs_sb_info *sbi = sb->s_fs_info;
572 squashfs_cache_delete(sbi->block_cache);
573 squashfs_cache_delete(sbi->fragment_cache);
574 squashfs_cache_delete(sbi->read_page);
575 sbi->thread_ops->destroy(sbi);
576 kfree(sbi->id_table);
577 kfree(sbi->fragment_index);
578 kfree(sbi->meta_index);
579 kfree(sbi->inode_lookup_table);
580 kfree(sbi->xattr_id_table);
581 kfree(sb->s_fs_info);
582 sb->s_fs_info = NULL;
586 static struct kmem_cache *squashfs_inode_cachep;
589 static void init_once(void *foo)
591 struct squashfs_inode_info *ei = foo;
593 inode_init_once(&ei->vfs_inode);
597 static int __init init_inodecache(void)
599 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
600 sizeof(struct squashfs_inode_info), 0,
601 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
604 return squashfs_inode_cachep ? 0 : -ENOMEM;
608 static void destroy_inodecache(void)
611 * Make sure all delayed rcu free inodes are flushed before we
615 kmem_cache_destroy(squashfs_inode_cachep);
619 static int __init init_squashfs_fs(void)
621 int err = init_inodecache();
626 err = register_filesystem(&squashfs_fs_type);
628 destroy_inodecache();
632 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
638 static void __exit exit_squashfs_fs(void)
640 unregister_filesystem(&squashfs_fs_type);
641 destroy_inodecache();
645 static struct inode *squashfs_alloc_inode(struct super_block *sb)
647 struct squashfs_inode_info *ei =
648 alloc_inode_sb(sb, squashfs_inode_cachep, GFP_KERNEL);
650 return ei ? &ei->vfs_inode : NULL;
654 static void squashfs_free_inode(struct inode *inode)
656 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
659 static struct file_system_type squashfs_fs_type = {
660 .owner = THIS_MODULE,
662 .init_fs_context = squashfs_init_fs_context,
663 .parameters = squashfs_fs_parameters,
664 .kill_sb = kill_block_super,
665 .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
667 MODULE_ALIAS_FS("squashfs");
669 static const struct super_operations squashfs_super_ops = {
670 .alloc_inode = squashfs_alloc_inode,
671 .free_inode = squashfs_free_inode,
672 .statfs = squashfs_statfs,
673 .put_super = squashfs_put_super,
674 .show_options = squashfs_show_options,
677 module_init(init_squashfs_fs);
678 module_exit(exit_squashfs_fs);
679 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
680 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
681 MODULE_LICENSE("GPL");