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