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/zlib.h> 39 #include <linux/magic.h> 40 41 #include "squashfs_fs.h" 42 #include "squashfs_fs_sb.h" 43 #include "squashfs_fs_i.h" 44 #include "squashfs.h" 45 46 static struct file_system_type squashfs_fs_type; 47 static const struct super_operations squashfs_super_ops; 48 49 static int supported_squashfs_filesystem(short major, short minor, short comp) 50 { 51 if (major < SQUASHFS_MAJOR) { 52 ERROR("Major/Minor mismatch, older Squashfs %d.%d " 53 "filesystems are unsupported\n", major, minor); 54 return -EINVAL; 55 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { 56 ERROR("Major/Minor mismatch, trying to mount newer " 57 "%d.%d filesystem\n", major, minor); 58 ERROR("Please update your kernel\n"); 59 return -EINVAL; 60 } 61 62 if (comp != ZLIB_COMPRESSION) 63 return -EINVAL; 64 65 return 0; 66 } 67 68 69 static int squashfs_fill_super(struct super_block *sb, void *data, int silent) 70 { 71 struct squashfs_sb_info *msblk; 72 struct squashfs_super_block *sblk = NULL; 73 char b[BDEVNAME_SIZE]; 74 struct inode *root; 75 long long root_inode; 76 unsigned short flags; 77 unsigned int fragments; 78 u64 lookup_table_start; 79 int err; 80 81 TRACE("Entered squashfs_fill_superblock\n"); 82 83 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); 84 if (sb->s_fs_info == NULL) { 85 ERROR("Failed to allocate squashfs_sb_info\n"); 86 return -ENOMEM; 87 } 88 msblk = sb->s_fs_info; 89 90 msblk->stream.workspace = kmalloc(zlib_inflate_workspacesize(), 91 GFP_KERNEL); 92 if (msblk->stream.workspace == NULL) { 93 ERROR("Failed to allocate zlib workspace\n"); 94 goto failure; 95 } 96 97 sblk = kzalloc(sizeof(*sblk), GFP_KERNEL); 98 if (sblk == NULL) { 99 ERROR("Failed to allocate squashfs_super_block\n"); 100 goto failure; 101 } 102 103 msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE); 104 msblk->devblksize_log2 = ffz(~msblk->devblksize); 105 106 mutex_init(&msblk->read_data_mutex); 107 mutex_init(&msblk->meta_index_mutex); 108 109 /* 110 * msblk->bytes_used is checked in squashfs_read_table to ensure reads 111 * are not beyond filesystem end. But as we're using 112 * squashfs_read_table here to read the superblock (including the value 113 * of bytes_used) we need to set it to an initial sensible dummy value 114 */ 115 msblk->bytes_used = sizeof(*sblk); 116 err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk)); 117 118 if (err < 0) { 119 ERROR("unable to read squashfs_super_block\n"); 120 goto failed_mount; 121 } 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 err = -EINVAL; 130 goto failed_mount; 131 } 132 133 /* Check the MAJOR & MINOR versions and compression type */ 134 err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major), 135 le16_to_cpu(sblk->s_minor), 136 le16_to_cpu(sblk->compression)); 137 if (err < 0) 138 goto failed_mount; 139 140 err = -EINVAL; 141 142 /* 143 * Check if there's xattrs in the filesystem. These are not 144 * supported in this version, so warn that they will be ignored. 145 */ 146 if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK) 147 ERROR("Xattrs in filesystem, these will be ignored\n"); 148 149 /* Check the filesystem does not extend beyond the end of the 150 block device */ 151 msblk->bytes_used = le64_to_cpu(sblk->bytes_used); 152 if (msblk->bytes_used < 0 || msblk->bytes_used > 153 i_size_read(sb->s_bdev->bd_inode)) 154 goto failed_mount; 155 156 /* Check block size for sanity */ 157 msblk->block_size = le32_to_cpu(sblk->block_size); 158 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) 159 goto failed_mount; 160 161 /* 162 * Check the system page size is not larger than the filesystem 163 * block size (by default 128K). This is currently not supported. 164 */ 165 if (PAGE_CACHE_SIZE > msblk->block_size) { 166 ERROR("Page size > filesystem block size (%d). This is " 167 "currently not supported!\n", msblk->block_size); 168 goto failed_mount; 169 } 170 171 msblk->block_log = le16_to_cpu(sblk->block_log); 172 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) 173 goto failed_mount; 174 175 /* Check the root inode for sanity */ 176 root_inode = le64_to_cpu(sblk->root_inode); 177 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) 178 goto failed_mount; 179 180 msblk->inode_table = le64_to_cpu(sblk->inode_table_start); 181 msblk->directory_table = le64_to_cpu(sblk->directory_table_start); 182 msblk->inodes = le32_to_cpu(sblk->inodes); 183 flags = le16_to_cpu(sblk->flags); 184 185 TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b)); 186 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) 187 ? "un" : ""); 188 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) 189 ? "un" : ""); 190 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); 191 TRACE("Block size %d\n", msblk->block_size); 192 TRACE("Number of inodes %d\n", msblk->inodes); 193 TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments)); 194 TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); 195 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); 196 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); 197 TRACE("sblk->fragment_table_start %llx\n", 198 (u64) le64_to_cpu(sblk->fragment_table_start)); 199 TRACE("sblk->id_table_start %llx\n", 200 (u64) le64_to_cpu(sblk->id_table_start)); 201 202 sb->s_maxbytes = MAX_LFS_FILESIZE; 203 sb->s_flags |= MS_RDONLY; 204 sb->s_op = &squashfs_super_ops; 205 206 err = -ENOMEM; 207 208 msblk->block_cache = squashfs_cache_init("metadata", 209 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); 210 if (msblk->block_cache == NULL) 211 goto failed_mount; 212 213 /* Allocate read_page block */ 214 msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size); 215 if (msblk->read_page == NULL) { 216 ERROR("Failed to allocate read_page block\n"); 217 goto failed_mount; 218 } 219 220 /* Allocate and read id index table */ 221 msblk->id_table = squashfs_read_id_index_table(sb, 222 le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids)); 223 if (IS_ERR(msblk->id_table)) { 224 err = PTR_ERR(msblk->id_table); 225 msblk->id_table = NULL; 226 goto failed_mount; 227 } 228 229 fragments = le32_to_cpu(sblk->fragments); 230 if (fragments == 0) 231 goto allocate_lookup_table; 232 233 msblk->fragment_cache = squashfs_cache_init("fragment", 234 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); 235 if (msblk->fragment_cache == NULL) { 236 err = -ENOMEM; 237 goto failed_mount; 238 } 239 240 /* Allocate and read fragment index table */ 241 msblk->fragment_index = squashfs_read_fragment_index_table(sb, 242 le64_to_cpu(sblk->fragment_table_start), fragments); 243 if (IS_ERR(msblk->fragment_index)) { 244 err = PTR_ERR(msblk->fragment_index); 245 msblk->fragment_index = NULL; 246 goto failed_mount; 247 } 248 249 allocate_lookup_table: 250 lookup_table_start = le64_to_cpu(sblk->lookup_table_start); 251 if (lookup_table_start == SQUASHFS_INVALID_BLK) 252 goto allocate_root; 253 254 /* Allocate and read inode lookup table */ 255 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, 256 lookup_table_start, msblk->inodes); 257 if (IS_ERR(msblk->inode_lookup_table)) { 258 err = PTR_ERR(msblk->inode_lookup_table); 259 msblk->inode_lookup_table = NULL; 260 goto failed_mount; 261 } 262 263 sb->s_export_op = &squashfs_export_ops; 264 265 allocate_root: 266 root = new_inode(sb); 267 if (!root) { 268 err = -ENOMEM; 269 goto failed_mount; 270 } 271 272 err = squashfs_read_inode(root, root_inode); 273 if (err) { 274 iget_failed(root); 275 goto failed_mount; 276 } 277 insert_inode_hash(root); 278 279 sb->s_root = d_alloc_root(root); 280 if (sb->s_root == NULL) { 281 ERROR("Root inode create failed\n"); 282 err = -ENOMEM; 283 iput(root); 284 goto failed_mount; 285 } 286 287 TRACE("Leaving squashfs_fill_super\n"); 288 kfree(sblk); 289 return 0; 290 291 failed_mount: 292 squashfs_cache_delete(msblk->block_cache); 293 squashfs_cache_delete(msblk->fragment_cache); 294 squashfs_cache_delete(msblk->read_page); 295 kfree(msblk->inode_lookup_table); 296 kfree(msblk->fragment_index); 297 kfree(msblk->id_table); 298 kfree(msblk->stream.workspace); 299 kfree(sb->s_fs_info); 300 sb->s_fs_info = NULL; 301 kfree(sblk); 302 return err; 303 304 failure: 305 kfree(msblk->stream.workspace); 306 kfree(sb->s_fs_info); 307 sb->s_fs_info = NULL; 308 return -ENOMEM; 309 } 310 311 312 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) 313 { 314 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; 315 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); 316 317 TRACE("Entered squashfs_statfs\n"); 318 319 buf->f_type = SQUASHFS_MAGIC; 320 buf->f_bsize = msblk->block_size; 321 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; 322 buf->f_bfree = buf->f_bavail = 0; 323 buf->f_files = msblk->inodes; 324 buf->f_ffree = 0; 325 buf->f_namelen = SQUASHFS_NAME_LEN; 326 buf->f_fsid.val[0] = (u32)id; 327 buf->f_fsid.val[1] = (u32)(id >> 32); 328 329 return 0; 330 } 331 332 333 static int squashfs_remount(struct super_block *sb, int *flags, char *data) 334 { 335 *flags |= MS_RDONLY; 336 return 0; 337 } 338 339 340 static void squashfs_put_super(struct super_block *sb) 341 { 342 lock_kernel(); 343 344 if (sb->s_fs_info) { 345 struct squashfs_sb_info *sbi = sb->s_fs_info; 346 squashfs_cache_delete(sbi->block_cache); 347 squashfs_cache_delete(sbi->fragment_cache); 348 squashfs_cache_delete(sbi->read_page); 349 kfree(sbi->id_table); 350 kfree(sbi->fragment_index); 351 kfree(sbi->meta_index); 352 kfree(sbi->stream.workspace); 353 kfree(sb->s_fs_info); 354 sb->s_fs_info = NULL; 355 } 356 357 unlock_kernel(); 358 } 359 360 361 static int squashfs_get_sb(struct file_system_type *fs_type, int flags, 362 const char *dev_name, void *data, 363 struct vfsmount *mnt) 364 { 365 return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super, 366 mnt); 367 } 368 369 370 static struct kmem_cache *squashfs_inode_cachep; 371 372 373 static void init_once(void *foo) 374 { 375 struct squashfs_inode_info *ei = foo; 376 377 inode_init_once(&ei->vfs_inode); 378 } 379 380 381 static int __init init_inodecache(void) 382 { 383 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", 384 sizeof(struct squashfs_inode_info), 0, 385 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); 386 387 return squashfs_inode_cachep ? 0 : -ENOMEM; 388 } 389 390 391 static void destroy_inodecache(void) 392 { 393 kmem_cache_destroy(squashfs_inode_cachep); 394 } 395 396 397 static int __init init_squashfs_fs(void) 398 { 399 int err = init_inodecache(); 400 401 if (err) 402 return err; 403 404 err = register_filesystem(&squashfs_fs_type); 405 if (err) { 406 destroy_inodecache(); 407 return err; 408 } 409 410 printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) " 411 "Phillip Lougher\n"); 412 413 return 0; 414 } 415 416 417 static void __exit exit_squashfs_fs(void) 418 { 419 unregister_filesystem(&squashfs_fs_type); 420 destroy_inodecache(); 421 } 422 423 424 static struct inode *squashfs_alloc_inode(struct super_block *sb) 425 { 426 struct squashfs_inode_info *ei = 427 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); 428 429 return ei ? &ei->vfs_inode : NULL; 430 } 431 432 433 static void squashfs_destroy_inode(struct inode *inode) 434 { 435 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); 436 } 437 438 439 static struct file_system_type squashfs_fs_type = { 440 .owner = THIS_MODULE, 441 .name = "squashfs", 442 .get_sb = squashfs_get_sb, 443 .kill_sb = kill_block_super, 444 .fs_flags = FS_REQUIRES_DEV 445 }; 446 447 static const struct super_operations squashfs_super_ops = { 448 .alloc_inode = squashfs_alloc_inode, 449 .destroy_inode = squashfs_destroy_inode, 450 .statfs = squashfs_statfs, 451 .put_super = squashfs_put_super, 452 .remount_fs = squashfs_remount 453 }; 454 455 module_init(init_squashfs_fs); 456 module_exit(exit_squashfs_fs); 457 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 458 MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>"); 459 MODULE_LICENSE("GPL"); 460