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
20 #include <linux/fs_context.h>
21 #include <linux/fs_parser.h>
22 #include <linux/vfs.h>
23 #include <linux/slab.h>
24 #include <linux/mutex.h>
25 #include <linux/seq_file.h>
26 #include <linux/pagemap.h>
27 #include <linux/init.h>
28 #include <linux/module.h>
29 #include <linux/magic.h>
30 #include <linux/xattr.h>
32 #include "squashfs_fs.h"
33 #include "squashfs_fs_sb.h"
34 #include "squashfs_fs_i.h"
36 #include "decompressor.h"
39 static struct file_system_type squashfs_fs_type;
40 static const struct super_operations squashfs_super_ops;
51 struct squashfs_mount_opts {
52 enum Opt_errors errors;
55 static const struct constant_table squashfs_param_errors[] = {
56 {"continue", Opt_errors_continue },
57 {"panic", Opt_errors_panic },
61 static const struct fs_parameter_spec squashfs_fs_parameters[] = {
62 fsparam_enum("errors", Opt_errors, squashfs_param_errors),
66 static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
68 struct squashfs_mount_opts *opts = fc->fs_private;
69 struct fs_parse_result result;
72 opt = fs_parse(fc, squashfs_fs_parameters, param, &result);
78 opts->errors = result.uint_32;
87 static const struct squashfs_decompressor *supported_squashfs_filesystem(
88 struct fs_context *fc,
89 short major, short minor, short id)
91 const struct squashfs_decompressor *decompressor;
93 if (major < SQUASHFS_MAJOR) {
94 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
95 "filesystems are unsupported", major, minor);
97 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
98 errorf(fc, "Major/Minor mismatch, trying to mount newer "
99 "%d.%d filesystem", major, minor);
100 errorf(fc, "Please update your kernel");
104 decompressor = squashfs_lookup_decompressor(id);
105 if (!decompressor->supported) {
106 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
115 static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
117 struct squashfs_mount_opts *opts = fc->fs_private;
118 struct squashfs_sb_info *msblk;
119 struct squashfs_super_block *sblk = NULL;
121 long long root_inode;
122 unsigned short flags;
123 unsigned int fragments;
124 u64 lookup_table_start, xattr_id_table_start, next_table;
127 TRACE("Entered squashfs_fill_superblock\n");
129 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
130 if (sb->s_fs_info == NULL) {
131 ERROR("Failed to allocate squashfs_sb_info\n");
134 msblk = sb->s_fs_info;
136 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
138 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
139 msblk->devblksize_log2 = ffz(~msblk->devblksize);
141 mutex_init(&msblk->meta_index_mutex);
144 * msblk->bytes_used is checked in squashfs_read_table to ensure reads
145 * are not beyond filesystem end. But as we're using
146 * squashfs_read_table here to read the superblock (including the value
147 * of bytes_used) we need to set it to an initial sensible dummy value
149 msblk->bytes_used = sizeof(*sblk);
150 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
153 errorf(fc, "unable to read squashfs_super_block");
161 /* Check it is a SQUASHFS superblock */
162 sb->s_magic = le32_to_cpu(sblk->s_magic);
163 if (sb->s_magic != SQUASHFS_MAGIC) {
164 if (!(fc->sb_flags & SB_SILENT))
165 errorf(fc, "Can't find a SQUASHFS superblock on %pg",
170 /* Check the MAJOR & MINOR versions and lookup compression type */
171 msblk->decompressor = supported_squashfs_filesystem(
173 le16_to_cpu(sblk->s_major),
174 le16_to_cpu(sblk->s_minor),
175 le16_to_cpu(sblk->compression));
176 if (msblk->decompressor == NULL)
179 /* Check the filesystem does not extend beyond the end of the
181 msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
182 if (msblk->bytes_used < 0 || msblk->bytes_used >
183 i_size_read(sb->s_bdev->bd_inode))
186 /* Check block size for sanity */
187 msblk->block_size = le32_to_cpu(sblk->block_size);
188 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
192 * Check the system page size is not larger than the filesystem
193 * block size (by default 128K). This is currently not supported.
195 if (PAGE_SIZE > msblk->block_size) {
196 errorf(fc, "Page size > filesystem block size (%d). This is "
197 "currently not supported!", msblk->block_size);
201 /* Check block log for sanity */
202 msblk->block_log = le16_to_cpu(sblk->block_log);
203 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
206 /* Check that block_size and block_log match */
207 if (msblk->block_size != (1 << msblk->block_log))
210 /* Check the root inode for sanity */
211 root_inode = le64_to_cpu(sblk->root_inode);
212 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
215 msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
216 msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
217 msblk->inodes = le32_to_cpu(sblk->inodes);
218 msblk->fragments = le32_to_cpu(sblk->fragments);
219 msblk->ids = le16_to_cpu(sblk->no_ids);
220 flags = le16_to_cpu(sblk->flags);
222 TRACE("Found valid superblock on %pg\n", sb->s_bdev);
223 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
225 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
227 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
228 TRACE("Block size %d\n", msblk->block_size);
229 TRACE("Number of inodes %d\n", msblk->inodes);
230 TRACE("Number of fragments %d\n", msblk->fragments);
231 TRACE("Number of ids %d\n", msblk->ids);
232 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
233 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
234 TRACE("sblk->fragment_table_start %llx\n",
235 (u64) le64_to_cpu(sblk->fragment_table_start));
236 TRACE("sblk->id_table_start %llx\n",
237 (u64) le64_to_cpu(sblk->id_table_start));
239 sb->s_maxbytes = MAX_LFS_FILESIZE;
241 sb->s_time_max = U32_MAX;
242 sb->s_flags |= SB_RDONLY;
243 sb->s_op = &squashfs_super_ops;
247 msblk->block_cache = squashfs_cache_init("metadata",
248 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
249 if (msblk->block_cache == NULL)
252 /* Allocate read_page block */
253 msblk->read_page = squashfs_cache_init("data",
254 squashfs_max_decompressors(), msblk->block_size);
255 if (msblk->read_page == NULL) {
256 errorf(fc, "Failed to allocate read_page block");
260 msblk->stream = squashfs_decompressor_setup(sb, flags);
261 if (IS_ERR(msblk->stream)) {
262 err = PTR_ERR(msblk->stream);
263 msblk->stream = NULL;
268 sb->s_xattr = squashfs_xattr_handlers;
269 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
270 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
271 next_table = msblk->bytes_used;
272 goto allocate_id_index_table;
275 /* Allocate and read xattr id lookup table */
276 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
277 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
278 if (IS_ERR(msblk->xattr_id_table)) {
279 errorf(fc, "unable to read xattr id index table");
280 err = PTR_ERR(msblk->xattr_id_table);
281 msblk->xattr_id_table = NULL;
282 if (err != -ENOTSUPP)
285 next_table = msblk->xattr_table;
287 allocate_id_index_table:
288 /* Allocate and read id index table */
289 msblk->id_table = squashfs_read_id_index_table(sb,
290 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
291 if (IS_ERR(msblk->id_table)) {
292 errorf(fc, "unable to read id index table");
293 err = PTR_ERR(msblk->id_table);
294 msblk->id_table = NULL;
297 next_table = le64_to_cpu(msblk->id_table[0]);
299 /* Handle inode lookup table */
300 lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
301 if (lookup_table_start == SQUASHFS_INVALID_BLK)
302 goto handle_fragments;
304 /* Allocate and read inode lookup table */
305 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
306 lookup_table_start, next_table, msblk->inodes);
307 if (IS_ERR(msblk->inode_lookup_table)) {
308 errorf(fc, "unable to read inode lookup table");
309 err = PTR_ERR(msblk->inode_lookup_table);
310 msblk->inode_lookup_table = NULL;
313 next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
315 sb->s_export_op = &squashfs_export_ops;
318 fragments = msblk->fragments;
320 goto check_directory_table;
322 msblk->fragment_cache = squashfs_cache_init("fragment",
323 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
324 if (msblk->fragment_cache == NULL) {
329 /* Allocate and read fragment index table */
330 msblk->fragment_index = squashfs_read_fragment_index_table(sb,
331 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
332 if (IS_ERR(msblk->fragment_index)) {
333 errorf(fc, "unable to read fragment index table");
334 err = PTR_ERR(msblk->fragment_index);
335 msblk->fragment_index = NULL;
338 next_table = le64_to_cpu(msblk->fragment_index[0]);
340 check_directory_table:
341 /* Sanity check directory_table */
342 if (msblk->directory_table > next_table) {
347 /* Sanity check inode_table */
348 if (msblk->inode_table >= msblk->directory_table) {
354 root = new_inode(sb);
360 err = squashfs_read_inode(root, root_inode);
362 make_bad_inode(root);
366 insert_inode_hash(root);
368 sb->s_root = d_make_root(root);
369 if (sb->s_root == NULL) {
370 ERROR("Root inode create failed\n");
375 TRACE("Leaving squashfs_fill_super\n");
380 errorf(fc, "squashfs image failed sanity check");
382 squashfs_cache_delete(msblk->block_cache);
383 squashfs_cache_delete(msblk->fragment_cache);
384 squashfs_cache_delete(msblk->read_page);
385 squashfs_decompressor_destroy(msblk);
386 kfree(msblk->inode_lookup_table);
387 kfree(msblk->fragment_index);
388 kfree(msblk->id_table);
389 kfree(msblk->xattr_id_table);
390 kfree(sb->s_fs_info);
391 sb->s_fs_info = NULL;
396 static int squashfs_get_tree(struct fs_context *fc)
398 return get_tree_bdev(fc, squashfs_fill_super);
401 static int squashfs_reconfigure(struct fs_context *fc)
403 struct super_block *sb = fc->root->d_sb;
404 struct squashfs_sb_info *msblk = sb->s_fs_info;
405 struct squashfs_mount_opts *opts = fc->fs_private;
407 sync_filesystem(fc->root->d_sb);
408 fc->sb_flags |= SB_RDONLY;
410 msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
415 static void squashfs_free_fs_context(struct fs_context *fc)
417 kfree(fc->fs_private);
420 static const struct fs_context_operations squashfs_context_ops = {
421 .get_tree = squashfs_get_tree,
422 .free = squashfs_free_fs_context,
423 .parse_param = squashfs_parse_param,
424 .reconfigure = squashfs_reconfigure,
427 static int squashfs_show_options(struct seq_file *s, struct dentry *root)
429 struct super_block *sb = root->d_sb;
430 struct squashfs_sb_info *msblk = sb->s_fs_info;
432 if (msblk->panic_on_errors)
433 seq_puts(s, ",errors=panic");
435 seq_puts(s, ",errors=continue");
440 static int squashfs_init_fs_context(struct fs_context *fc)
442 struct squashfs_mount_opts *opts;
444 opts = kzalloc(sizeof(*opts), GFP_KERNEL);
448 fc->fs_private = opts;
449 fc->ops = &squashfs_context_ops;
453 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
455 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
456 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
458 TRACE("Entered squashfs_statfs\n");
460 buf->f_type = SQUASHFS_MAGIC;
461 buf->f_bsize = msblk->block_size;
462 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
463 buf->f_bfree = buf->f_bavail = 0;
464 buf->f_files = msblk->inodes;
466 buf->f_namelen = SQUASHFS_NAME_LEN;
467 buf->f_fsid = u64_to_fsid(id);
473 static void squashfs_put_super(struct super_block *sb)
476 struct squashfs_sb_info *sbi = sb->s_fs_info;
477 squashfs_cache_delete(sbi->block_cache);
478 squashfs_cache_delete(sbi->fragment_cache);
479 squashfs_cache_delete(sbi->read_page);
480 squashfs_decompressor_destroy(sbi);
481 kfree(sbi->id_table);
482 kfree(sbi->fragment_index);
483 kfree(sbi->meta_index);
484 kfree(sbi->inode_lookup_table);
485 kfree(sbi->xattr_id_table);
486 kfree(sb->s_fs_info);
487 sb->s_fs_info = NULL;
491 static struct kmem_cache *squashfs_inode_cachep;
494 static void init_once(void *foo)
496 struct squashfs_inode_info *ei = foo;
498 inode_init_once(&ei->vfs_inode);
502 static int __init init_inodecache(void)
504 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
505 sizeof(struct squashfs_inode_info), 0,
506 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
509 return squashfs_inode_cachep ? 0 : -ENOMEM;
513 static void destroy_inodecache(void)
516 * Make sure all delayed rcu free inodes are flushed before we
520 kmem_cache_destroy(squashfs_inode_cachep);
524 static int __init init_squashfs_fs(void)
526 int err = init_inodecache();
531 err = register_filesystem(&squashfs_fs_type);
533 destroy_inodecache();
537 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
543 static void __exit exit_squashfs_fs(void)
545 unregister_filesystem(&squashfs_fs_type);
546 destroy_inodecache();
550 static struct inode *squashfs_alloc_inode(struct super_block *sb)
552 struct squashfs_inode_info *ei =
553 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
555 return ei ? &ei->vfs_inode : NULL;
559 static void squashfs_free_inode(struct inode *inode)
561 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
564 static struct file_system_type squashfs_fs_type = {
565 .owner = THIS_MODULE,
567 .init_fs_context = squashfs_init_fs_context,
568 .parameters = squashfs_fs_parameters,
569 .kill_sb = kill_block_super,
570 .fs_flags = FS_REQUIRES_DEV
572 MODULE_ALIAS_FS("squashfs");
574 static const struct super_operations squashfs_super_ops = {
575 .alloc_inode = squashfs_alloc_inode,
576 .free_inode = squashfs_free_inode,
577 .statfs = squashfs_statfs,
578 .put_super = squashfs_put_super,
579 .show_options = squashfs_show_options,
582 module_init(init_squashfs_fs);
583 module_exit(exit_squashfs_fs);
584 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
585 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
586 MODULE_LICENSE("GPL");