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/zlib.h> 38 #include <linux/magic.h> 39 40 #include "squashfs_fs.h" 41 #include "squashfs_fs_sb.h" 42 #include "squashfs_fs_i.h" 43 #include "squashfs.h" 44 45 static struct file_system_type squashfs_fs_type; 46 static struct super_operations squashfs_super_ops; 47 48 static int supported_squashfs_filesystem(short major, short minor, short comp) 49 { 50 if (major < SQUASHFS_MAJOR) { 51 ERROR("Major/Minor mismatch, older Squashfs %d.%d " 52 "filesystems are unsupported\n", major, minor); 53 return -EINVAL; 54 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { 55 ERROR("Major/Minor mismatch, trying to mount newer " 56 "%d.%d filesystem\n", major, minor); 57 ERROR("Please update your kernel\n"); 58 return -EINVAL; 59 } 60 61 if (comp != ZLIB_COMPRESSION) 62 return -EINVAL; 63 64 return 0; 65 } 66 67 68 static int squashfs_fill_super(struct super_block *sb, void *data, int silent) 69 { 70 struct squashfs_sb_info *msblk; 71 struct squashfs_super_block *sblk = NULL; 72 char b[BDEVNAME_SIZE]; 73 struct inode *root; 74 long long root_inode; 75 unsigned short flags; 76 unsigned int fragments; 77 u64 lookup_table_start; 78 int err; 79 80 TRACE("Entered squashfs_fill_superblock\n"); 81 82 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); 83 if (sb->s_fs_info == NULL) { 84 ERROR("Failed to allocate squashfs_sb_info\n"); 85 return -ENOMEM; 86 } 87 msblk = sb->s_fs_info; 88 89 msblk->stream.workspace = kmalloc(zlib_inflate_workspacesize(), 90 GFP_KERNEL); 91 if (msblk->stream.workspace == NULL) { 92 ERROR("Failed to allocate zlib workspace\n"); 93 goto failure; 94 } 95 96 sblk = kzalloc(sizeof(*sblk), GFP_KERNEL); 97 if (sblk == NULL) { 98 ERROR("Failed to allocate squashfs_super_block\n"); 99 goto failure; 100 } 101 102 msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE); 103 msblk->devblksize_log2 = ffz(~msblk->devblksize); 104 105 mutex_init(&msblk->read_data_mutex); 106 mutex_init(&msblk->meta_index_mutex); 107 108 /* 109 * msblk->bytes_used is checked in squashfs_read_table to ensure reads 110 * are not beyond filesystem end. But as we're using 111 * squashfs_read_table here to read the superblock (including the value 112 * of bytes_used) we need to set it to an initial sensible dummy value 113 */ 114 msblk->bytes_used = sizeof(*sblk); 115 err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk)); 116 117 if (err < 0) { 118 ERROR("unable to read squashfs_super_block\n"); 119 goto failed_mount; 120 } 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 err = -EINVAL; 129 goto failed_mount; 130 } 131 132 /* Check the MAJOR & MINOR versions and compression type */ 133 err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major), 134 le16_to_cpu(sblk->s_minor), 135 le16_to_cpu(sblk->compression)); 136 if (err < 0) 137 goto failed_mount; 138 139 err = -EINVAL; 140 141 /* 142 * Check if there's xattrs in the filesystem. These are not 143 * supported in this version, so warn that they will be ignored. 144 */ 145 if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK) 146 ERROR("Xattrs in filesystem, these will be ignored\n"); 147 148 /* Check the filesystem does not extend beyond the end of the 149 block device */ 150 msblk->bytes_used = le64_to_cpu(sblk->bytes_used); 151 if (msblk->bytes_used < 0 || msblk->bytes_used > 152 i_size_read(sb->s_bdev->bd_inode)) 153 goto failed_mount; 154 155 /* Check block size for sanity */ 156 msblk->block_size = le32_to_cpu(sblk->block_size); 157 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) 158 goto failed_mount; 159 160 /* 161 * Check the system page size is not larger than the filesystem 162 * block size (by default 128K). This is currently not supported. 163 */ 164 if (PAGE_CACHE_SIZE > msblk->block_size) { 165 ERROR("Page size > filesystem block size (%d). This is " 166 "currently not supported!\n", msblk->block_size); 167 goto failed_mount; 168 } 169 170 msblk->block_log = le16_to_cpu(sblk->block_log); 171 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) 172 goto failed_mount; 173 174 /* Check the root inode for sanity */ 175 root_inode = le64_to_cpu(sblk->root_inode); 176 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) 177 goto failed_mount; 178 179 msblk->inode_table = le64_to_cpu(sblk->inode_table_start); 180 msblk->directory_table = le64_to_cpu(sblk->directory_table_start); 181 msblk->inodes = le32_to_cpu(sblk->inodes); 182 flags = le16_to_cpu(sblk->flags); 183 184 TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b)); 185 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) 186 ? "un" : ""); 187 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) 188 ? "un" : ""); 189 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); 190 TRACE("Block size %d\n", msblk->block_size); 191 TRACE("Number of inodes %d\n", msblk->inodes); 192 TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments)); 193 TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); 194 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); 195 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); 196 TRACE("sblk->fragment_table_start %llx\n", 197 (u64) le64_to_cpu(sblk->fragment_table_start)); 198 TRACE("sblk->id_table_start %llx\n", 199 (u64) le64_to_cpu(sblk->id_table_start)); 200 201 sb->s_maxbytes = MAX_LFS_FILESIZE; 202 sb->s_flags |= MS_RDONLY; 203 sb->s_op = &squashfs_super_ops; 204 205 err = -ENOMEM; 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_root; 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_root: 265 root = new_inode(sb); 266 if (!root) { 267 err = -ENOMEM; 268 goto failed_mount; 269 } 270 271 err = squashfs_read_inode(root, root_inode); 272 if (err) { 273 iget_failed(root); 274 goto failed_mount; 275 } 276 insert_inode_hash(root); 277 278 sb->s_root = d_alloc_root(root); 279 if (sb->s_root == NULL) { 280 ERROR("Root inode create failed\n"); 281 err = -ENOMEM; 282 iput(root); 283 goto failed_mount; 284 } 285 286 TRACE("Leaving squashfs_fill_super\n"); 287 kfree(sblk); 288 return 0; 289 290 failed_mount: 291 squashfs_cache_delete(msblk->block_cache); 292 squashfs_cache_delete(msblk->fragment_cache); 293 squashfs_cache_delete(msblk->read_page); 294 kfree(msblk->inode_lookup_table); 295 kfree(msblk->fragment_index); 296 kfree(msblk->id_table); 297 kfree(msblk->stream.workspace); 298 kfree(sb->s_fs_info); 299 sb->s_fs_info = NULL; 300 kfree(sblk); 301 return err; 302 303 failure: 304 kfree(msblk->stream.workspace); 305 kfree(sb->s_fs_info); 306 sb->s_fs_info = NULL; 307 return -ENOMEM; 308 } 309 310 311 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) 312 { 313 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; 314 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); 315 316 TRACE("Entered squashfs_statfs\n"); 317 318 buf->f_type = SQUASHFS_MAGIC; 319 buf->f_bsize = msblk->block_size; 320 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; 321 buf->f_bfree = buf->f_bavail = 0; 322 buf->f_files = msblk->inodes; 323 buf->f_ffree = 0; 324 buf->f_namelen = SQUASHFS_NAME_LEN; 325 buf->f_fsid.val[0] = (u32)id; 326 buf->f_fsid.val[1] = (u32)(id >> 32); 327 328 return 0; 329 } 330 331 332 static int squashfs_remount(struct super_block *sb, int *flags, char *data) 333 { 334 *flags |= MS_RDONLY; 335 return 0; 336 } 337 338 339 static void squashfs_put_super(struct super_block *sb) 340 { 341 if (sb->s_fs_info) { 342 struct squashfs_sb_info *sbi = sb->s_fs_info; 343 squashfs_cache_delete(sbi->block_cache); 344 squashfs_cache_delete(sbi->fragment_cache); 345 squashfs_cache_delete(sbi->read_page); 346 kfree(sbi->id_table); 347 kfree(sbi->fragment_index); 348 kfree(sbi->meta_index); 349 kfree(sbi->stream.workspace); 350 kfree(sb->s_fs_info); 351 sb->s_fs_info = NULL; 352 } 353 } 354 355 356 static int squashfs_get_sb(struct file_system_type *fs_type, int flags, 357 const char *dev_name, void *data, 358 struct vfsmount *mnt) 359 { 360 return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super, 361 mnt); 362 } 363 364 365 static struct kmem_cache *squashfs_inode_cachep; 366 367 368 static void init_once(void *foo) 369 { 370 struct squashfs_inode_info *ei = foo; 371 372 inode_init_once(&ei->vfs_inode); 373 } 374 375 376 static int __init init_inodecache(void) 377 { 378 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", 379 sizeof(struct squashfs_inode_info), 0, 380 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); 381 382 return squashfs_inode_cachep ? 0 : -ENOMEM; 383 } 384 385 386 static void destroy_inodecache(void) 387 { 388 kmem_cache_destroy(squashfs_inode_cachep); 389 } 390 391 392 static int __init init_squashfs_fs(void) 393 { 394 int err = init_inodecache(); 395 396 if (err) 397 return err; 398 399 err = register_filesystem(&squashfs_fs_type); 400 if (err) { 401 destroy_inodecache(); 402 return err; 403 } 404 405 printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) " 406 "Phillip Lougher\n"); 407 408 return 0; 409 } 410 411 412 static void __exit exit_squashfs_fs(void) 413 { 414 unregister_filesystem(&squashfs_fs_type); 415 destroy_inodecache(); 416 } 417 418 419 static struct inode *squashfs_alloc_inode(struct super_block *sb) 420 { 421 struct squashfs_inode_info *ei = 422 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); 423 424 return ei ? &ei->vfs_inode : NULL; 425 } 426 427 428 static void squashfs_destroy_inode(struct inode *inode) 429 { 430 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); 431 } 432 433 434 static struct file_system_type squashfs_fs_type = { 435 .owner = THIS_MODULE, 436 .name = "squashfs", 437 .get_sb = squashfs_get_sb, 438 .kill_sb = kill_block_super, 439 .fs_flags = FS_REQUIRES_DEV 440 }; 441 442 static struct super_operations squashfs_super_ops = { 443 .alloc_inode = squashfs_alloc_inode, 444 .destroy_inode = squashfs_destroy_inode, 445 .statfs = squashfs_statfs, 446 .put_super = squashfs_put_super, 447 .remount_fs = squashfs_remount 448 }; 449 450 module_init(init_squashfs_fs); 451 module_exit(exit_squashfs_fs); 452 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 453 MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>"); 454 MODULE_LICENSE("GPL"); 455