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 #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, next_table; 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 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); 99 msblk->devblksize_log2 = ffz(~msblk->devblksize); 100 101 mutex_init(&msblk->meta_index_mutex); 102 103 /* 104 * msblk->bytes_used is checked in squashfs_read_table to ensure reads 105 * are not beyond filesystem end. But as we're using 106 * squashfs_read_table here to read the superblock (including the value 107 * of bytes_used) we need to set it to an initial sensible dummy value 108 */ 109 msblk->bytes_used = sizeof(*sblk); 110 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk)); 111 112 if (IS_ERR(sblk)) { 113 ERROR("unable to read squashfs_super_block\n"); 114 err = PTR_ERR(sblk); 115 sblk = NULL; 116 goto failed_mount; 117 } 118 119 err = -EINVAL; 120 121 /* Check it is a SQUASHFS superblock */ 122 sb->s_magic = le32_to_cpu(sblk->s_magic); 123 if (sb->s_magic != SQUASHFS_MAGIC) { 124 if (!silent) 125 ERROR("Can't find a SQUASHFS superblock on %s\n", 126 bdevname(sb->s_bdev, b)); 127 goto failed_mount; 128 } 129 130 /* Check the MAJOR & MINOR versions and lookup compression type */ 131 msblk->decompressor = supported_squashfs_filesystem( 132 le16_to_cpu(sblk->s_major), 133 le16_to_cpu(sblk->s_minor), 134 le16_to_cpu(sblk->compression)); 135 if (msblk->decompressor == NULL) 136 goto failed_mount; 137 138 /* Check the filesystem does not extend beyond the end of the 139 block device */ 140 msblk->bytes_used = le64_to_cpu(sblk->bytes_used); 141 if (msblk->bytes_used < 0 || msblk->bytes_used > 142 i_size_read(sb->s_bdev->bd_inode)) 143 goto failed_mount; 144 145 /* Check block size for sanity */ 146 msblk->block_size = le32_to_cpu(sblk->block_size); 147 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) 148 goto failed_mount; 149 150 /* 151 * Check the system page size is not larger than the filesystem 152 * block size (by default 128K). This is currently not supported. 153 */ 154 if (PAGE_CACHE_SIZE > msblk->block_size) { 155 ERROR("Page size > filesystem block size (%d). This is " 156 "currently not supported!\n", msblk->block_size); 157 goto failed_mount; 158 } 159 160 /* Check block log for sanity */ 161 msblk->block_log = le16_to_cpu(sblk->block_log); 162 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) 163 goto failed_mount; 164 165 /* Check that block_size and block_log match */ 166 if (msblk->block_size != (1 << msblk->block_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->block_cache = squashfs_cache_init("metadata", 203 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); 204 if (msblk->block_cache == NULL) 205 goto failed_mount; 206 207 /* Allocate read_page block */ 208 msblk->read_page = squashfs_cache_init("data", 209 squashfs_max_decompressors(), msblk->block_size); 210 if (msblk->read_page == NULL) { 211 ERROR("Failed to allocate read_page block\n"); 212 goto failed_mount; 213 } 214 215 msblk->stream = squashfs_decompressor_setup(sb, flags); 216 if (IS_ERR(msblk->stream)) { 217 err = PTR_ERR(msblk->stream); 218 msblk->stream = NULL; 219 goto failed_mount; 220 } 221 222 /* Handle xattrs */ 223 sb->s_xattr = squashfs_xattr_handlers; 224 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start); 225 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) { 226 next_table = msblk->bytes_used; 227 goto allocate_id_index_table; 228 } 229 230 /* Allocate and read xattr id lookup table */ 231 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb, 232 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids); 233 if (IS_ERR(msblk->xattr_id_table)) { 234 ERROR("unable to read xattr id index table\n"); 235 err = PTR_ERR(msblk->xattr_id_table); 236 msblk->xattr_id_table = NULL; 237 if (err != -ENOTSUPP) 238 goto failed_mount; 239 } 240 next_table = msblk->xattr_table; 241 242 allocate_id_index_table: 243 /* Allocate and read id index table */ 244 msblk->id_table = squashfs_read_id_index_table(sb, 245 le64_to_cpu(sblk->id_table_start), next_table, 246 le16_to_cpu(sblk->no_ids)); 247 if (IS_ERR(msblk->id_table)) { 248 ERROR("unable to read id index table\n"); 249 err = PTR_ERR(msblk->id_table); 250 msblk->id_table = NULL; 251 goto failed_mount; 252 } 253 next_table = le64_to_cpu(msblk->id_table[0]); 254 255 /* Handle inode lookup table */ 256 lookup_table_start = le64_to_cpu(sblk->lookup_table_start); 257 if (lookup_table_start == SQUASHFS_INVALID_BLK) 258 goto handle_fragments; 259 260 /* Allocate and read inode lookup table */ 261 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, 262 lookup_table_start, next_table, msblk->inodes); 263 if (IS_ERR(msblk->inode_lookup_table)) { 264 ERROR("unable to read inode lookup table\n"); 265 err = PTR_ERR(msblk->inode_lookup_table); 266 msblk->inode_lookup_table = NULL; 267 goto failed_mount; 268 } 269 next_table = le64_to_cpu(msblk->inode_lookup_table[0]); 270 271 sb->s_export_op = &squashfs_export_ops; 272 273 handle_fragments: 274 fragments = le32_to_cpu(sblk->fragments); 275 if (fragments == 0) 276 goto check_directory_table; 277 278 msblk->fragment_cache = squashfs_cache_init("fragment", 279 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); 280 if (msblk->fragment_cache == NULL) { 281 err = -ENOMEM; 282 goto failed_mount; 283 } 284 285 /* Allocate and read fragment index table */ 286 msblk->fragment_index = squashfs_read_fragment_index_table(sb, 287 le64_to_cpu(sblk->fragment_table_start), next_table, fragments); 288 if (IS_ERR(msblk->fragment_index)) { 289 ERROR("unable to read fragment index table\n"); 290 err = PTR_ERR(msblk->fragment_index); 291 msblk->fragment_index = NULL; 292 goto failed_mount; 293 } 294 next_table = le64_to_cpu(msblk->fragment_index[0]); 295 296 check_directory_table: 297 /* Sanity check directory_table */ 298 if (msblk->directory_table > next_table) { 299 err = -EINVAL; 300 goto failed_mount; 301 } 302 303 /* Sanity check inode_table */ 304 if (msblk->inode_table >= msblk->directory_table) { 305 err = -EINVAL; 306 goto failed_mount; 307 } 308 309 /* allocate root */ 310 root = new_inode(sb); 311 if (!root) { 312 err = -ENOMEM; 313 goto failed_mount; 314 } 315 316 err = squashfs_read_inode(root, root_inode); 317 if (err) { 318 make_bad_inode(root); 319 iput(root); 320 goto failed_mount; 321 } 322 insert_inode_hash(root); 323 324 sb->s_root = d_make_root(root); 325 if (sb->s_root == NULL) { 326 ERROR("Root inode create failed\n"); 327 err = -ENOMEM; 328 goto failed_mount; 329 } 330 331 TRACE("Leaving squashfs_fill_super\n"); 332 kfree(sblk); 333 return 0; 334 335 failed_mount: 336 squashfs_cache_delete(msblk->block_cache); 337 squashfs_cache_delete(msblk->fragment_cache); 338 squashfs_cache_delete(msblk->read_page); 339 squashfs_decompressor_destroy(msblk); 340 kfree(msblk->inode_lookup_table); 341 kfree(msblk->fragment_index); 342 kfree(msblk->id_table); 343 kfree(msblk->xattr_id_table); 344 kfree(sb->s_fs_info); 345 sb->s_fs_info = NULL; 346 kfree(sblk); 347 return err; 348 } 349 350 351 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) 352 { 353 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; 354 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); 355 356 TRACE("Entered squashfs_statfs\n"); 357 358 buf->f_type = SQUASHFS_MAGIC; 359 buf->f_bsize = msblk->block_size; 360 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; 361 buf->f_bfree = buf->f_bavail = 0; 362 buf->f_files = msblk->inodes; 363 buf->f_ffree = 0; 364 buf->f_namelen = SQUASHFS_NAME_LEN; 365 buf->f_fsid.val[0] = (u32)id; 366 buf->f_fsid.val[1] = (u32)(id >> 32); 367 368 return 0; 369 } 370 371 372 static int squashfs_remount(struct super_block *sb, int *flags, char *data) 373 { 374 *flags |= MS_RDONLY; 375 return 0; 376 } 377 378 379 static void squashfs_put_super(struct super_block *sb) 380 { 381 if (sb->s_fs_info) { 382 struct squashfs_sb_info *sbi = sb->s_fs_info; 383 squashfs_cache_delete(sbi->block_cache); 384 squashfs_cache_delete(sbi->fragment_cache); 385 squashfs_cache_delete(sbi->read_page); 386 squashfs_decompressor_destroy(sbi); 387 kfree(sbi->id_table); 388 kfree(sbi->fragment_index); 389 kfree(sbi->meta_index); 390 kfree(sbi->inode_lookup_table); 391 kfree(sbi->xattr_id_table); 392 kfree(sb->s_fs_info); 393 sb->s_fs_info = NULL; 394 } 395 } 396 397 398 static struct dentry *squashfs_mount(struct file_system_type *fs_type, 399 int flags, const char *dev_name, void *data) 400 { 401 return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super); 402 } 403 404 405 static struct kmem_cache *squashfs_inode_cachep; 406 407 408 static void init_once(void *foo) 409 { 410 struct squashfs_inode_info *ei = foo; 411 412 inode_init_once(&ei->vfs_inode); 413 } 414 415 416 static int __init init_inodecache(void) 417 { 418 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", 419 sizeof(struct squashfs_inode_info), 0, 420 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); 421 422 return squashfs_inode_cachep ? 0 : -ENOMEM; 423 } 424 425 426 static void destroy_inodecache(void) 427 { 428 /* 429 * Make sure all delayed rcu free inodes are flushed before we 430 * destroy cache. 431 */ 432 rcu_barrier(); 433 kmem_cache_destroy(squashfs_inode_cachep); 434 } 435 436 437 static int __init init_squashfs_fs(void) 438 { 439 int err = init_inodecache(); 440 441 if (err) 442 return err; 443 444 err = register_filesystem(&squashfs_fs_type); 445 if (err) { 446 destroy_inodecache(); 447 return err; 448 } 449 450 printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) " 451 "Phillip Lougher\n"); 452 453 return 0; 454 } 455 456 457 static void __exit exit_squashfs_fs(void) 458 { 459 unregister_filesystem(&squashfs_fs_type); 460 destroy_inodecache(); 461 } 462 463 464 static struct inode *squashfs_alloc_inode(struct super_block *sb) 465 { 466 struct squashfs_inode_info *ei = 467 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); 468 469 return ei ? &ei->vfs_inode : NULL; 470 } 471 472 473 static void squashfs_i_callback(struct rcu_head *head) 474 { 475 struct inode *inode = container_of(head, struct inode, i_rcu); 476 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); 477 } 478 479 static void squashfs_destroy_inode(struct inode *inode) 480 { 481 call_rcu(&inode->i_rcu, squashfs_i_callback); 482 } 483 484 485 static struct file_system_type squashfs_fs_type = { 486 .owner = THIS_MODULE, 487 .name = "squashfs", 488 .mount = squashfs_mount, 489 .kill_sb = kill_block_super, 490 .fs_flags = FS_REQUIRES_DEV 491 }; 492 MODULE_ALIAS_FS("squashfs"); 493 494 static const struct super_operations squashfs_super_ops = { 495 .alloc_inode = squashfs_alloc_inode, 496 .destroy_inode = squashfs_destroy_inode, 497 .statfs = squashfs_statfs, 498 .put_super = squashfs_put_super, 499 .remount_fs = squashfs_remount 500 }; 501 502 module_init(init_squashfs_fs); 503 module_exit(exit_squashfs_fs); 504 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 505 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>"); 506 MODULE_LICENSE("GPL"); 507