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, BLOCK_SIZE); 99 msblk->devblksize_log2 = ffz(~msblk->devblksize); 100 101 mutex_init(&msblk->read_data_mutex); 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 %s\n", 127 bdevname(sb->s_bdev, b)); 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_CACHE_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 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 the root inode for sanity */ 166 root_inode = le64_to_cpu(sblk->root_inode); 167 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) 168 goto failed_mount; 169 170 msblk->inode_table = le64_to_cpu(sblk->inode_table_start); 171 msblk->directory_table = le64_to_cpu(sblk->directory_table_start); 172 msblk->inodes = le32_to_cpu(sblk->inodes); 173 flags = le16_to_cpu(sblk->flags); 174 175 TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b)); 176 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) 177 ? "un" : ""); 178 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) 179 ? "un" : ""); 180 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); 181 TRACE("Block size %d\n", msblk->block_size); 182 TRACE("Number of inodes %d\n", msblk->inodes); 183 TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments)); 184 TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); 185 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); 186 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); 187 TRACE("sblk->fragment_table_start %llx\n", 188 (u64) le64_to_cpu(sblk->fragment_table_start)); 189 TRACE("sblk->id_table_start %llx\n", 190 (u64) le64_to_cpu(sblk->id_table_start)); 191 192 sb->s_maxbytes = MAX_LFS_FILESIZE; 193 sb->s_flags |= MS_RDONLY; 194 sb->s_op = &squashfs_super_ops; 195 196 err = -ENOMEM; 197 198 msblk->block_cache = squashfs_cache_init("metadata", 199 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); 200 if (msblk->block_cache == NULL) 201 goto failed_mount; 202 203 /* Allocate read_page block */ 204 msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size); 205 if (msblk->read_page == NULL) { 206 ERROR("Failed to allocate read_page block\n"); 207 goto failed_mount; 208 } 209 210 msblk->stream = squashfs_decompressor_init(sb, flags); 211 if (IS_ERR(msblk->stream)) { 212 err = PTR_ERR(msblk->stream); 213 msblk->stream = NULL; 214 goto failed_mount; 215 } 216 217 /* Handle xattrs */ 218 sb->s_xattr = squashfs_xattr_handlers; 219 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start); 220 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) { 221 next_table = msblk->bytes_used; 222 goto allocate_id_index_table; 223 } 224 225 /* Allocate and read xattr id lookup table */ 226 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb, 227 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids); 228 if (IS_ERR(msblk->xattr_id_table)) { 229 ERROR("unable to read xattr id index table\n"); 230 err = PTR_ERR(msblk->xattr_id_table); 231 msblk->xattr_id_table = NULL; 232 if (err != -ENOTSUPP) 233 goto failed_mount; 234 } 235 next_table = msblk->xattr_table; 236 237 allocate_id_index_table: 238 /* Allocate and read id index table */ 239 msblk->id_table = squashfs_read_id_index_table(sb, 240 le64_to_cpu(sblk->id_table_start), next_table, 241 le16_to_cpu(sblk->no_ids)); 242 if (IS_ERR(msblk->id_table)) { 243 ERROR("unable to read id index table\n"); 244 err = PTR_ERR(msblk->id_table); 245 msblk->id_table = NULL; 246 goto failed_mount; 247 } 248 next_table = le64_to_cpu(msblk->id_table[0]); 249 250 /* Handle inode lookup table */ 251 lookup_table_start = le64_to_cpu(sblk->lookup_table_start); 252 if (lookup_table_start == SQUASHFS_INVALID_BLK) 253 goto handle_fragments; 254 255 /* Allocate and read inode lookup table */ 256 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, 257 lookup_table_start, next_table, msblk->inodes); 258 if (IS_ERR(msblk->inode_lookup_table)) { 259 ERROR("unable to read inode lookup table\n"); 260 err = PTR_ERR(msblk->inode_lookup_table); 261 msblk->inode_lookup_table = NULL; 262 goto failed_mount; 263 } 264 next_table = le64_to_cpu(msblk->inode_lookup_table[0]); 265 266 sb->s_export_op = &squashfs_export_ops; 267 268 handle_fragments: 269 fragments = le32_to_cpu(sblk->fragments); 270 if (fragments == 0) 271 goto check_directory_table; 272 273 msblk->fragment_cache = squashfs_cache_init("fragment", 274 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); 275 if (msblk->fragment_cache == NULL) { 276 err = -ENOMEM; 277 goto failed_mount; 278 } 279 280 /* Allocate and read fragment index table */ 281 msblk->fragment_index = squashfs_read_fragment_index_table(sb, 282 le64_to_cpu(sblk->fragment_table_start), next_table, fragments); 283 if (IS_ERR(msblk->fragment_index)) { 284 ERROR("unable to read fragment index table\n"); 285 err = PTR_ERR(msblk->fragment_index); 286 msblk->fragment_index = NULL; 287 goto failed_mount; 288 } 289 next_table = le64_to_cpu(msblk->fragment_index[0]); 290 291 check_directory_table: 292 /* Sanity check directory_table */ 293 if (msblk->directory_table >= next_table) { 294 err = -EINVAL; 295 goto failed_mount; 296 } 297 298 /* Sanity check inode_table */ 299 if (msblk->inode_table >= msblk->directory_table) { 300 err = -EINVAL; 301 goto failed_mount; 302 } 303 304 /* allocate root */ 305 root = new_inode(sb); 306 if (!root) { 307 err = -ENOMEM; 308 goto failed_mount; 309 } 310 311 err = squashfs_read_inode(root, root_inode); 312 if (err) { 313 make_bad_inode(root); 314 iput(root); 315 goto failed_mount; 316 } 317 insert_inode_hash(root); 318 319 sb->s_root = d_alloc_root(root); 320 if (sb->s_root == NULL) { 321 ERROR("Root inode create failed\n"); 322 err = -ENOMEM; 323 iput(root); 324 goto failed_mount; 325 } 326 327 TRACE("Leaving squashfs_fill_super\n"); 328 kfree(sblk); 329 return 0; 330 331 failed_mount: 332 squashfs_cache_delete(msblk->block_cache); 333 squashfs_cache_delete(msblk->fragment_cache); 334 squashfs_cache_delete(msblk->read_page); 335 squashfs_decompressor_free(msblk, msblk->stream); 336 kfree(msblk->inode_lookup_table); 337 kfree(msblk->fragment_index); 338 kfree(msblk->id_table); 339 kfree(msblk->xattr_id_table); 340 kfree(sb->s_fs_info); 341 sb->s_fs_info = NULL; 342 kfree(sblk); 343 return err; 344 } 345 346 347 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) 348 { 349 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; 350 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); 351 352 TRACE("Entered squashfs_statfs\n"); 353 354 buf->f_type = SQUASHFS_MAGIC; 355 buf->f_bsize = msblk->block_size; 356 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; 357 buf->f_bfree = buf->f_bavail = 0; 358 buf->f_files = msblk->inodes; 359 buf->f_ffree = 0; 360 buf->f_namelen = SQUASHFS_NAME_LEN; 361 buf->f_fsid.val[0] = (u32)id; 362 buf->f_fsid.val[1] = (u32)(id >> 32); 363 364 return 0; 365 } 366 367 368 static int squashfs_remount(struct super_block *sb, int *flags, char *data) 369 { 370 *flags |= MS_RDONLY; 371 return 0; 372 } 373 374 375 static void squashfs_put_super(struct super_block *sb) 376 { 377 if (sb->s_fs_info) { 378 struct squashfs_sb_info *sbi = sb->s_fs_info; 379 squashfs_cache_delete(sbi->block_cache); 380 squashfs_cache_delete(sbi->fragment_cache); 381 squashfs_cache_delete(sbi->read_page); 382 squashfs_decompressor_free(sbi, sbi->stream); 383 kfree(sbi->id_table); 384 kfree(sbi->fragment_index); 385 kfree(sbi->meta_index); 386 kfree(sbi->inode_lookup_table); 387 kfree(sbi->xattr_id_table); 388 kfree(sb->s_fs_info); 389 sb->s_fs_info = NULL; 390 } 391 } 392 393 394 static struct dentry *squashfs_mount(struct file_system_type *fs_type, 395 int flags, const char *dev_name, void *data) 396 { 397 return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super); 398 } 399 400 401 static struct kmem_cache *squashfs_inode_cachep; 402 403 404 static void init_once(void *foo) 405 { 406 struct squashfs_inode_info *ei = foo; 407 408 inode_init_once(&ei->vfs_inode); 409 } 410 411 412 static int __init init_inodecache(void) 413 { 414 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", 415 sizeof(struct squashfs_inode_info), 0, 416 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); 417 418 return squashfs_inode_cachep ? 0 : -ENOMEM; 419 } 420 421 422 static void destroy_inodecache(void) 423 { 424 kmem_cache_destroy(squashfs_inode_cachep); 425 } 426 427 428 static int __init init_squashfs_fs(void) 429 { 430 int err = init_inodecache(); 431 432 if (err) 433 return err; 434 435 err = register_filesystem(&squashfs_fs_type); 436 if (err) { 437 destroy_inodecache(); 438 return err; 439 } 440 441 printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) " 442 "Phillip Lougher\n"); 443 444 return 0; 445 } 446 447 448 static void __exit exit_squashfs_fs(void) 449 { 450 unregister_filesystem(&squashfs_fs_type); 451 destroy_inodecache(); 452 } 453 454 455 static struct inode *squashfs_alloc_inode(struct super_block *sb) 456 { 457 struct squashfs_inode_info *ei = 458 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); 459 460 return ei ? &ei->vfs_inode : NULL; 461 } 462 463 464 static void squashfs_i_callback(struct rcu_head *head) 465 { 466 struct inode *inode = container_of(head, struct inode, i_rcu); 467 INIT_LIST_HEAD(&inode->i_dentry); 468 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); 469 } 470 471 static void squashfs_destroy_inode(struct inode *inode) 472 { 473 call_rcu(&inode->i_rcu, squashfs_i_callback); 474 } 475 476 477 static struct file_system_type squashfs_fs_type = { 478 .owner = THIS_MODULE, 479 .name = "squashfs", 480 .mount = squashfs_mount, 481 .kill_sb = kill_block_super, 482 .fs_flags = FS_REQUIRES_DEV 483 }; 484 485 static const struct super_operations squashfs_super_ops = { 486 .alloc_inode = squashfs_alloc_inode, 487 .destroy_inode = squashfs_destroy_inode, 488 .statfs = squashfs_statfs, 489 .put_super = squashfs_put_super, 490 .remount_fs = squashfs_remount 491 }; 492 493 module_init(init_squashfs_fs); 494 module_exit(exit_squashfs_fs); 495 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 496 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>"); 497 MODULE_LICENSE("GPL"); 498