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 (at) 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 39 #include "squashfs_fs.h" 40 #include "squashfs_fs_sb.h" 41 #include "squashfs_fs_i.h" 42 #include "squashfs.h" 43 44 static struct file_system_type squashfs_fs_type; 45 static struct super_operations squashfs_super_ops; 46 47 static int supported_squashfs_filesystem(short major, short minor, short comp) 48 { 49 if (major < SQUASHFS_MAJOR) { 50 ERROR("Major/Minor mismatch, older Squashfs %d.%d " 51 "filesystems are unsupported\n", major, minor); 52 return -EINVAL; 53 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { 54 ERROR("Major/Minor mismatch, trying to mount newer " 55 "%d.%d filesystem\n", major, minor); 56 ERROR("Please update your kernel\n"); 57 return -EINVAL; 58 } 59 60 if (comp != ZLIB_COMPRESSION) 61 return -EINVAL; 62 63 return 0; 64 } 65 66 67 static int squashfs_fill_super(struct super_block *sb, void *data, int silent) 68 { 69 struct squashfs_sb_info *msblk; 70 struct squashfs_super_block *sblk = NULL; 71 char b[BDEVNAME_SIZE]; 72 struct inode *root; 73 long long root_inode; 74 unsigned short flags; 75 unsigned int fragments; 76 u64 lookup_table_start; 77 int err; 78 79 TRACE("Entered squashfs_fill_superblock\n"); 80 81 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); 82 if (sb->s_fs_info == NULL) { 83 ERROR("Failed to allocate squashfs_sb_info\n"); 84 return -ENOMEM; 85 } 86 msblk = sb->s_fs_info; 87 88 msblk->stream.workspace = kmalloc(zlib_inflate_workspacesize(), 89 GFP_KERNEL); 90 if (msblk->stream.workspace == NULL) { 91 ERROR("Failed to allocate zlib workspace\n"); 92 goto failure; 93 } 94 95 sblk = kzalloc(sizeof(*sblk), GFP_KERNEL); 96 if (sblk == NULL) { 97 ERROR("Failed to allocate squashfs_super_block\n"); 98 goto failure; 99 } 100 101 msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE); 102 msblk->devblksize_log2 = ffz(~msblk->devblksize); 103 104 mutex_init(&msblk->read_data_mutex); 105 mutex_init(&msblk->meta_index_mutex); 106 107 /* 108 * msblk->bytes_used is checked in squashfs_read_table to ensure reads 109 * are not beyond filesystem end. But as we're using 110 * squashfs_read_table here to read the superblock (including the value 111 * of bytes_used) we need to set it to an initial sensible dummy value 112 */ 113 msblk->bytes_used = sizeof(*sblk); 114 err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk)); 115 116 if (err < 0) { 117 ERROR("unable to read squashfs_super_block\n"); 118 goto failed_mount; 119 } 120 121 /* Check it is a SQUASHFS superblock */ 122 sb->s_magic = le32_to_cpu(sblk->s_magic); 123 if (sb->s_magic != SQUASHFS_MAGIC) { 124 if (!silent) 125 ERROR("Can't find a SQUASHFS superblock on %s\n", 126 bdevname(sb->s_bdev, b)); 127 err = -EINVAL; 128 goto failed_mount; 129 } 130 131 /* Check the MAJOR & MINOR versions and compression type */ 132 err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major), 133 le16_to_cpu(sblk->s_minor), 134 le16_to_cpu(sblk->compression)); 135 if (err < 0) 136 goto failed_mount; 137 138 err = -EINVAL; 139 140 /* 141 * Check if there's xattrs in the filesystem. These are not 142 * supported in this version, so warn that they will be ignored. 143 */ 144 if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK) 145 ERROR("Xattrs in filesystem, these will be ignored\n"); 146 147 /* Check the filesystem does not extend beyond the end of the 148 block device */ 149 msblk->bytes_used = le64_to_cpu(sblk->bytes_used); 150 if (msblk->bytes_used < 0 || msblk->bytes_used > 151 i_size_read(sb->s_bdev->bd_inode)) 152 goto failed_mount; 153 154 /* Check block size for sanity */ 155 msblk->block_size = le32_to_cpu(sblk->block_size); 156 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) 157 goto failed_mount; 158 159 msblk->block_log = le16_to_cpu(sblk->block_log); 160 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) 161 goto failed_mount; 162 163 /* Check the root inode for sanity */ 164 root_inode = le64_to_cpu(sblk->root_inode); 165 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) 166 goto failed_mount; 167 168 msblk->inode_table = le64_to_cpu(sblk->inode_table_start); 169 msblk->directory_table = le64_to_cpu(sblk->directory_table_start); 170 msblk->inodes = le32_to_cpu(sblk->inodes); 171 flags = le16_to_cpu(sblk->flags); 172 173 TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b)); 174 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) 175 ? "un" : ""); 176 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) 177 ? "un" : ""); 178 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); 179 TRACE("Block size %d\n", msblk->block_size); 180 TRACE("Number of inodes %d\n", msblk->inodes); 181 TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments)); 182 TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); 183 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); 184 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); 185 TRACE("sblk->fragment_table_start %llx\n", 186 (u64) le64_to_cpu(sblk->fragment_table_start)); 187 TRACE("sblk->id_table_start %llx\n", 188 (u64) le64_to_cpu(sblk->id_table_start)); 189 190 sb->s_maxbytes = MAX_LFS_FILESIZE; 191 sb->s_flags |= MS_RDONLY; 192 sb->s_op = &squashfs_super_ops; 193 194 err = -ENOMEM; 195 196 msblk->block_cache = squashfs_cache_init("metadata", 197 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); 198 if (msblk->block_cache == NULL) 199 goto failed_mount; 200 201 /* Allocate read_page block */ 202 msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size); 203 if (msblk->read_page == NULL) { 204 ERROR("Failed to allocate read_page block\n"); 205 goto failed_mount; 206 } 207 208 /* Allocate and read id index table */ 209 msblk->id_table = squashfs_read_id_index_table(sb, 210 le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids)); 211 if (IS_ERR(msblk->id_table)) { 212 err = PTR_ERR(msblk->id_table); 213 msblk->id_table = NULL; 214 goto failed_mount; 215 } 216 217 fragments = le32_to_cpu(sblk->fragments); 218 if (fragments == 0) 219 goto allocate_lookup_table; 220 221 msblk->fragment_cache = squashfs_cache_init("fragment", 222 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); 223 if (msblk->fragment_cache == NULL) { 224 err = -ENOMEM; 225 goto failed_mount; 226 } 227 228 /* Allocate and read fragment index table */ 229 msblk->fragment_index = squashfs_read_fragment_index_table(sb, 230 le64_to_cpu(sblk->fragment_table_start), fragments); 231 if (IS_ERR(msblk->fragment_index)) { 232 err = PTR_ERR(msblk->fragment_index); 233 msblk->fragment_index = NULL; 234 goto failed_mount; 235 } 236 237 allocate_lookup_table: 238 lookup_table_start = le64_to_cpu(sblk->lookup_table_start); 239 if (lookup_table_start == SQUASHFS_INVALID_BLK) 240 goto allocate_root; 241 242 /* Allocate and read inode lookup table */ 243 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, 244 lookup_table_start, msblk->inodes); 245 if (IS_ERR(msblk->inode_lookup_table)) { 246 err = PTR_ERR(msblk->inode_lookup_table); 247 msblk->inode_lookup_table = NULL; 248 goto failed_mount; 249 } 250 251 sb->s_export_op = &squashfs_export_ops; 252 253 allocate_root: 254 root = new_inode(sb); 255 if (!root) { 256 err = -ENOMEM; 257 goto failed_mount; 258 } 259 260 err = squashfs_read_inode(root, root_inode); 261 if (err) { 262 iget_failed(root); 263 goto failed_mount; 264 } 265 insert_inode_hash(root); 266 267 sb->s_root = d_alloc_root(root); 268 if (sb->s_root == NULL) { 269 ERROR("Root inode create failed\n"); 270 err = -ENOMEM; 271 iput(root); 272 goto failed_mount; 273 } 274 275 TRACE("Leaving squashfs_fill_super\n"); 276 kfree(sblk); 277 return 0; 278 279 failed_mount: 280 squashfs_cache_delete(msblk->block_cache); 281 squashfs_cache_delete(msblk->fragment_cache); 282 squashfs_cache_delete(msblk->read_page); 283 kfree(msblk->inode_lookup_table); 284 kfree(msblk->fragment_index); 285 kfree(msblk->id_table); 286 kfree(msblk->stream.workspace); 287 kfree(sb->s_fs_info); 288 sb->s_fs_info = NULL; 289 kfree(sblk); 290 return err; 291 292 failure: 293 kfree(msblk->stream.workspace); 294 kfree(sb->s_fs_info); 295 sb->s_fs_info = NULL; 296 return -ENOMEM; 297 } 298 299 300 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) 301 { 302 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; 303 304 TRACE("Entered squashfs_statfs\n"); 305 306 buf->f_type = SQUASHFS_MAGIC; 307 buf->f_bsize = msblk->block_size; 308 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; 309 buf->f_bfree = buf->f_bavail = 0; 310 buf->f_files = msblk->inodes; 311 buf->f_ffree = 0; 312 buf->f_namelen = SQUASHFS_NAME_LEN; 313 314 return 0; 315 } 316 317 318 static int squashfs_remount(struct super_block *sb, int *flags, char *data) 319 { 320 *flags |= MS_RDONLY; 321 return 0; 322 } 323 324 325 static void squashfs_put_super(struct super_block *sb) 326 { 327 if (sb->s_fs_info) { 328 struct squashfs_sb_info *sbi = sb->s_fs_info; 329 squashfs_cache_delete(sbi->block_cache); 330 squashfs_cache_delete(sbi->fragment_cache); 331 squashfs_cache_delete(sbi->read_page); 332 kfree(sbi->id_table); 333 kfree(sbi->fragment_index); 334 kfree(sbi->meta_index); 335 kfree(sbi->stream.workspace); 336 kfree(sb->s_fs_info); 337 sb->s_fs_info = NULL; 338 } 339 } 340 341 342 static int squashfs_get_sb(struct file_system_type *fs_type, int flags, 343 const char *dev_name, void *data, 344 struct vfsmount *mnt) 345 { 346 return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super, 347 mnt); 348 } 349 350 351 static struct kmem_cache *squashfs_inode_cachep; 352 353 354 static void init_once(void *foo) 355 { 356 struct squashfs_inode_info *ei = foo; 357 358 inode_init_once(&ei->vfs_inode); 359 } 360 361 362 static int __init init_inodecache(void) 363 { 364 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", 365 sizeof(struct squashfs_inode_info), 0, 366 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); 367 368 return squashfs_inode_cachep ? 0 : -ENOMEM; 369 } 370 371 372 static void destroy_inodecache(void) 373 { 374 kmem_cache_destroy(squashfs_inode_cachep); 375 } 376 377 378 static int __init init_squashfs_fs(void) 379 { 380 int err = init_inodecache(); 381 382 if (err) 383 return err; 384 385 err = register_filesystem(&squashfs_fs_type); 386 if (err) { 387 destroy_inodecache(); 388 return err; 389 } 390 391 printk(KERN_INFO "squashfs: version 4.0 (2009/01/03) " 392 "Phillip Lougher\n"); 393 394 return 0; 395 } 396 397 398 static void __exit exit_squashfs_fs(void) 399 { 400 unregister_filesystem(&squashfs_fs_type); 401 destroy_inodecache(); 402 } 403 404 405 static struct inode *squashfs_alloc_inode(struct super_block *sb) 406 { 407 struct squashfs_inode_info *ei = 408 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); 409 410 return ei ? &ei->vfs_inode : NULL; 411 } 412 413 414 static void squashfs_destroy_inode(struct inode *inode) 415 { 416 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); 417 } 418 419 420 static struct file_system_type squashfs_fs_type = { 421 .owner = THIS_MODULE, 422 .name = "squashfs", 423 .get_sb = squashfs_get_sb, 424 .kill_sb = kill_block_super, 425 .fs_flags = FS_REQUIRES_DEV 426 }; 427 428 static struct super_operations squashfs_super_ops = { 429 .alloc_inode = squashfs_alloc_inode, 430 .destroy_inode = squashfs_destroy_inode, 431 .statfs = squashfs_statfs, 432 .put_super = squashfs_put_super, 433 .remount_fs = squashfs_remount 434 }; 435 436 module_init(init_squashfs_fs); 437 module_exit(exit_squashfs_fs); 438 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 439 MODULE_AUTHOR("Phillip Lougher <phillip (at) lougher.demon.co.uk>"); 440 MODULE_LICENSE("GPL"); 441
