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/smp_lock.h> 34 #include <linux/mutex.h> 35 #include <linux/pagemap.h> 36 #include <linux/init.h> 37 #include <linux/module.h> 38 #include <linux/magic.h> 39 #include <linux/xattr.h> 40 41 #include "squashfs_fs.h" 42 #include "squashfs_fs_sb.h" 43 #include "squashfs_fs_i.h" 44 #include "squashfs.h" 45 #include "decompressor.h" 46 #include "xattr.h" 47 48 static struct file_system_type squashfs_fs_type; 49 static const struct super_operations squashfs_super_ops; 50 51 static const struct squashfs_decompressor *supported_squashfs_filesystem(short 52 major, short minor, short id) 53 { 54 const struct squashfs_decompressor *decompressor; 55 56 if (major < SQUASHFS_MAJOR) { 57 ERROR("Major/Minor mismatch, older Squashfs %d.%d " 58 "filesystems are unsupported\n", major, minor); 59 return NULL; 60 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { 61 ERROR("Major/Minor mismatch, trying to mount newer " 62 "%d.%d filesystem\n", major, minor); 63 ERROR("Please update your kernel\n"); 64 return NULL; 65 } 66 67 decompressor = squashfs_lookup_decompressor(id); 68 if (!decompressor->supported) { 69 ERROR("Filesystem uses \"%s\" compression. This is not " 70 "supported\n", decompressor->name); 71 return NULL; 72 } 73 74 return decompressor; 75 } 76 77 78 static int squashfs_fill_super(struct super_block *sb, void *data, int silent) 79 { 80 struct squashfs_sb_info *msblk; 81 struct squashfs_super_block *sblk = NULL; 82 char b[BDEVNAME_SIZE]; 83 struct inode *root; 84 long long root_inode; 85 unsigned short flags; 86 unsigned int fragments; 87 u64 lookup_table_start, xattr_id_table_start; 88 int err; 89 90 TRACE("Entered squashfs_fill_superblock\n"); 91 92 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); 93 if (sb->s_fs_info == NULL) { 94 ERROR("Failed to allocate squashfs_sb_info\n"); 95 return -ENOMEM; 96 } 97 msblk = sb->s_fs_info; 98 99 sblk = kzalloc(sizeof(*sblk), GFP_KERNEL); 100 if (sblk == NULL) { 101 ERROR("Failed to allocate squashfs_super_block\n"); 102 goto failure; 103 } 104 105 msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE); 106 msblk->devblksize_log2 = ffz(~msblk->devblksize); 107 108 mutex_init(&msblk->read_data_mutex); 109 mutex_init(&msblk->meta_index_mutex); 110 111 /* 112 * msblk->bytes_used is checked in squashfs_read_table to ensure reads 113 * are not beyond filesystem end. But as we're using 114 * squashfs_read_table here to read the superblock (including the value 115 * of bytes_used) we need to set it to an initial sensible dummy value 116 */ 117 msblk->bytes_used = sizeof(*sblk); 118 err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk)); 119 120 if (err < 0) { 121 ERROR("unable to read squashfs_super_block\n"); 122 goto failed_mount; 123 } 124 125 err = -EINVAL; 126 127 /* Check it is a SQUASHFS superblock */ 128 sb->s_magic = le32_to_cpu(sblk->s_magic); 129 if (sb->s_magic != SQUASHFS_MAGIC) { 130 if (!silent) 131 ERROR("Can't find a SQUASHFS superblock on %s\n", 132 bdevname(sb->s_bdev, b)); 133 goto failed_mount; 134 } 135 136 /* Check the MAJOR & MINOR versions and lookup compression type */ 137 msblk->decompressor = supported_squashfs_filesystem( 138 le16_to_cpu(sblk->s_major), 139 le16_to_cpu(sblk->s_minor), 140 le16_to_cpu(sblk->compression)); 141 if (msblk->decompressor == NULL) 142 goto failed_mount; 143 144 /* Check the filesystem does not extend beyond the end of the 145 block device */ 146 msblk->bytes_used = le64_to_cpu(sblk->bytes_used); 147 if (msblk->bytes_used < 0 || msblk->bytes_used > 148 i_size_read(sb->s_bdev->bd_inode)) 149 goto failed_mount; 150 151 /* Check block size for sanity */ 152 msblk->block_size = le32_to_cpu(sblk->block_size); 153 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) 154 goto failed_mount; 155 156 /* 157 * Check the system page size is not larger than the filesystem 158 * block size (by default 128K). This is currently not supported. 159 */ 160 if (PAGE_CACHE_SIZE > msblk->block_size) { 161 ERROR("Page size > filesystem block size (%d). This is " 162 "currently not supported!\n", msblk->block_size); 163 goto failed_mount; 164 } 165 166 msblk->block_log = le16_to_cpu(sblk->block_log); 167 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) 168 goto failed_mount; 169 170 /* Check the root inode for sanity */ 171 root_inode = le64_to_cpu(sblk->root_inode); 172 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) 173 goto failed_mount; 174 175 msblk->inode_table = le64_to_cpu(sblk->inode_table_start); 176 msblk->directory_table = le64_to_cpu(sblk->directory_table_start); 177 msblk->inodes = le32_to_cpu(sblk->inodes); 178 flags = le16_to_cpu(sblk->flags); 179 180 TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b)); 181 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) 182 ? "un" : ""); 183 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) 184 ? "un" : ""); 185 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); 186 TRACE("Block size %d\n", msblk->block_size); 187 TRACE("Number of inodes %d\n", msblk->inodes); 188 TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments)); 189 TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); 190 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); 191 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); 192 TRACE("sblk->fragment_table_start %llx\n", 193 (u64) le64_to_cpu(sblk->fragment_table_start)); 194 TRACE("sblk->id_table_start %llx\n", 195 (u64) le64_to_cpu(sblk->id_table_start)); 196 197 sb->s_maxbytes = MAX_LFS_FILESIZE; 198 sb->s_flags |= MS_RDONLY; 199 sb->s_op = &squashfs_super_ops; 200 201 err = -ENOMEM; 202 203 msblk->stream = squashfs_decompressor_init(msblk); 204 if (msblk->stream == NULL) 205 goto failed_mount; 206 207 msblk->block_cache = squashfs_cache_init("metadata", 208 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); 209 if (msblk->block_cache == NULL) 210 goto failed_mount; 211 212 /* Allocate read_page block */ 213 msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size); 214 if (msblk->read_page == NULL) { 215 ERROR("Failed to allocate read_page block\n"); 216 goto failed_mount; 217 } 218 219 /* Allocate and read id index table */ 220 msblk->id_table = squashfs_read_id_index_table(sb, 221 le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids)); 222 if (IS_ERR(msblk->id_table)) { 223 err = PTR_ERR(msblk->id_table); 224 msblk->id_table = NULL; 225 goto failed_mount; 226 } 227 228 fragments = le32_to_cpu(sblk->fragments); 229 if (fragments == 0) 230 goto allocate_lookup_table; 231 232 msblk->fragment_cache = squashfs_cache_init("fragment", 233 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); 234 if (msblk->fragment_cache == NULL) { 235 err = -ENOMEM; 236 goto failed_mount; 237 } 238 239 /* Allocate and read fragment index table */ 240 msblk->fragment_index = squashfs_read_fragment_index_table(sb, 241 le64_to_cpu(sblk->fragment_table_start), fragments); 242 if (IS_ERR(msblk->fragment_index)) { 243 err = PTR_ERR(msblk->fragment_index); 244 msblk->fragment_index = NULL; 245 goto failed_mount; 246 } 247 248 allocate_lookup_table: 249 lookup_table_start = le64_to_cpu(sblk->lookup_table_start); 250 if (lookup_table_start == SQUASHFS_INVALID_BLK) 251 goto allocate_xattr_table; 252 253 /* Allocate and read inode lookup table */ 254 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, 255 lookup_table_start, msblk->inodes); 256 if (IS_ERR(msblk->inode_lookup_table)) { 257 err = PTR_ERR(msblk->inode_lookup_table); 258 msblk->inode_lookup_table = NULL; 259 goto failed_mount; 260 } 261 262 sb->s_export_op = &squashfs_export_ops; 263 264 allocate_xattr_table: 265 sb->s_xattr = squashfs_xattr_handlers; 266 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start); 267 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) 268 goto allocate_root; 269 270 /* Allocate and read xattr id lookup table */ 271 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb, 272 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids); 273 if (IS_ERR(msblk->xattr_id_table)) { 274 err = PTR_ERR(msblk->xattr_id_table); 275 msblk->xattr_id_table = NULL; 276 if (err != -ENOTSUPP) 277 goto failed_mount; 278 } 279 allocate_root: 280 root = new_inode(sb); 281 if (!root) { 282 err = -ENOMEM; 283 goto failed_mount; 284 } 285 286 err = squashfs_read_inode(root, root_inode); 287 if (err) { 288 make_bad_inode(root); 289 iput(root); 290 goto failed_mount; 291 } 292 insert_inode_hash(root); 293 294 sb->s_root = d_alloc_root(root); 295 if (sb->s_root == NULL) { 296 ERROR("Root inode create failed\n"); 297 err = -ENOMEM; 298 iput(root); 299 goto failed_mount; 300 } 301 302 TRACE("Leaving squashfs_fill_super\n"); 303 kfree(sblk); 304 return 0; 305 306 failed_mount: 307 squashfs_cache_delete(msblk->block_cache); 308 squashfs_cache_delete(msblk->fragment_cache); 309 squashfs_cache_delete(msblk->read_page); 310 squashfs_decompressor_free(msblk, msblk->stream); 311 kfree(msblk->inode_lookup_table); 312 kfree(msblk->fragment_index); 313 kfree(msblk->id_table); 314 kfree(msblk->xattr_id_table); 315 kfree(sb->s_fs_info); 316 sb->s_fs_info = NULL; 317 kfree(sblk); 318 return err; 319 320 failure: 321 kfree(sb->s_fs_info); 322 sb->s_fs_info = NULL; 323 return -ENOMEM; 324 } 325 326 327 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) 328 { 329 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; 330 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); 331 332 TRACE("Entered squashfs_statfs\n"); 333 334 buf->f_type = SQUASHFS_MAGIC; 335 buf->f_bsize = msblk->block_size; 336 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; 337 buf->f_bfree = buf->f_bavail = 0; 338 buf->f_files = msblk->inodes; 339 buf->f_ffree = 0; 340 buf->f_namelen = SQUASHFS_NAME_LEN; 341 buf->f_fsid.val[0] = (u32)id; 342 buf->f_fsid.val[1] = (u32)(id >> 32); 343 344 return 0; 345 } 346 347 348 static int squashfs_remount(struct super_block *sb, int *flags, char *data) 349 { 350 *flags |= MS_RDONLY; 351 return 0; 352 } 353 354 355 static void squashfs_put_super(struct super_block *sb) 356 { 357 lock_kernel(); 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 unlock_kernel(); 375 } 376 377 378 static int squashfs_get_sb(struct file_system_type *fs_type, int flags, 379 const char *dev_name, void *data, 380 struct vfsmount *mnt) 381 { 382 return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super, 383 mnt); 384 } 385 386 387 static struct kmem_cache *squashfs_inode_cachep; 388 389 390 static void init_once(void *foo) 391 { 392 struct squashfs_inode_info *ei = foo; 393 394 inode_init_once(&ei->vfs_inode); 395 } 396 397 398 static int __init init_inodecache(void) 399 { 400 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", 401 sizeof(struct squashfs_inode_info), 0, 402 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); 403 404 return squashfs_inode_cachep ? 0 : -ENOMEM; 405 } 406 407 408 static void destroy_inodecache(void) 409 { 410 kmem_cache_destroy(squashfs_inode_cachep); 411 } 412 413 414 static int __init init_squashfs_fs(void) 415 { 416 int err = init_inodecache(); 417 418 if (err) 419 return err; 420 421 err = register_filesystem(&squashfs_fs_type); 422 if (err) { 423 destroy_inodecache(); 424 return err; 425 } 426 427 printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) " 428 "Phillip Lougher\n"); 429 430 return 0; 431 } 432 433 434 static void __exit exit_squashfs_fs(void) 435 { 436 unregister_filesystem(&squashfs_fs_type); 437 destroy_inodecache(); 438 } 439 440 441 static struct inode *squashfs_alloc_inode(struct super_block *sb) 442 { 443 struct squashfs_inode_info *ei = 444 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); 445 446 return ei ? &ei->vfs_inode : NULL; 447 } 448 449 450 static void squashfs_destroy_inode(struct inode *inode) 451 { 452 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); 453 } 454 455 456 static struct file_system_type squashfs_fs_type = { 457 .owner = THIS_MODULE, 458 .name = "squashfs", 459 .get_sb = squashfs_get_sb, 460 .kill_sb = kill_block_super, 461 .fs_flags = FS_REQUIRES_DEV 462 }; 463 464 static const struct super_operations squashfs_super_ops = { 465 .alloc_inode = squashfs_alloc_inode, 466 .destroy_inode = squashfs_destroy_inode, 467 .statfs = squashfs_statfs, 468 .put_super = squashfs_put_super, 469 .remount_fs = squashfs_remount 470 }; 471 472 module_init(init_squashfs_fs); 473 module_exit(exit_squashfs_fs); 474 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 475 MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>"); 476 MODULE_LICENSE("GPL"); 477