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 49 static struct file_system_type squashfs_fs_type; 50 static const struct super_operations squashfs_super_ops; 51 52 static 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 79 static 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; 243 244 allocate_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; 274 275 handle_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]); 297 298 check_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; 336 337 failed_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 } 351 352 353 static 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 } 372 373 374 static int squashfs_remount(struct super_block *sb, int *flags, char *data) 375 { 376 sync_filesystem(sb); 377 *flags |= MS_RDONLY; 378 return 0; 379 } 380 381 382 static 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 } 399 400 401 static 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 } 406 407 408 static struct kmem_cache *squashfs_inode_cachep; 409 410 411 static void init_once(void *foo) 412 { 413 struct squashfs_inode_info *ei = foo; 414 415 inode_init_once(&ei->vfs_inode); 416 } 417 418 419 static 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 } 427 428 429 static 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 } 438 439 440 static 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 } 457 458 459 static void __exit exit_squashfs_fs(void) 460 { 461 unregister_filesystem(&squashfs_fs_type); 462 destroy_inodecache(); 463 } 464 465 466 static 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 } 473 474 475 static 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 } 480 481 static void squashfs_destroy_inode(struct inode *inode) 482 { 483 call_rcu(&inode->i_rcu, squashfs_i_callback); 484 } 485 486 487 static 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 }; 494 MODULE_ALIAS_FS("squashfs"); 495 496 static 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 }; 503 504 module_init(init_squashfs_fs); 505 module_exit(exit_squashfs_fs); 506 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 507 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>"); 508 MODULE_LICENSE("GPL"); 509