Phillip Lougher | 0aa6661 | 2009-01-05 08:46:25 +0000 | [diff] [blame] | 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> |
Qinghuang Feng | 1bcbf31 | 2009-01-15 13:51:03 -0800 | [diff] [blame] | 38 | #include <linux/magic.h> |
Phillip Lougher | 0aa6661 | 2009-01-05 08:46:25 +0000 | [diff] [blame] | 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 | msblk->block_log = le16_to_cpu(sblk->block_log); |
| 161 | if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) |
| 162 | goto failed_mount; |
| 163 | |
| 164 | /* Check the root inode for sanity */ |
| 165 | root_inode = le64_to_cpu(sblk->root_inode); |
| 166 | if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) |
| 167 | goto failed_mount; |
| 168 | |
| 169 | msblk->inode_table = le64_to_cpu(sblk->inode_table_start); |
| 170 | msblk->directory_table = le64_to_cpu(sblk->directory_table_start); |
| 171 | msblk->inodes = le32_to_cpu(sblk->inodes); |
| 172 | flags = le16_to_cpu(sblk->flags); |
| 173 | |
| 174 | TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b)); |
| 175 | TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) |
| 176 | ? "un" : ""); |
| 177 | TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) |
| 178 | ? "un" : ""); |
| 179 | TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); |
| 180 | TRACE("Block size %d\n", msblk->block_size); |
| 181 | TRACE("Number of inodes %d\n", msblk->inodes); |
| 182 | TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments)); |
| 183 | TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); |
| 184 | TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); |
| 185 | TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); |
| 186 | TRACE("sblk->fragment_table_start %llx\n", |
| 187 | (u64) le64_to_cpu(sblk->fragment_table_start)); |
| 188 | TRACE("sblk->id_table_start %llx\n", |
| 189 | (u64) le64_to_cpu(sblk->id_table_start)); |
| 190 | |
| 191 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
| 192 | sb->s_flags |= MS_RDONLY; |
| 193 | sb->s_op = &squashfs_super_ops; |
| 194 | |
| 195 | err = -ENOMEM; |
| 196 | |
| 197 | msblk->block_cache = squashfs_cache_init("metadata", |
| 198 | SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); |
| 199 | if (msblk->block_cache == NULL) |
| 200 | goto failed_mount; |
| 201 | |
| 202 | /* Allocate read_page block */ |
| 203 | msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size); |
| 204 | if (msblk->read_page == NULL) { |
| 205 | ERROR("Failed to allocate read_page block\n"); |
| 206 | goto failed_mount; |
| 207 | } |
| 208 | |
| 209 | /* Allocate and read id index table */ |
| 210 | msblk->id_table = squashfs_read_id_index_table(sb, |
| 211 | le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids)); |
| 212 | if (IS_ERR(msblk->id_table)) { |
| 213 | err = PTR_ERR(msblk->id_table); |
| 214 | msblk->id_table = NULL; |
| 215 | goto failed_mount; |
| 216 | } |
| 217 | |
| 218 | fragments = le32_to_cpu(sblk->fragments); |
| 219 | if (fragments == 0) |
| 220 | goto allocate_lookup_table; |
| 221 | |
| 222 | msblk->fragment_cache = squashfs_cache_init("fragment", |
| 223 | SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); |
| 224 | if (msblk->fragment_cache == NULL) { |
| 225 | err = -ENOMEM; |
| 226 | goto failed_mount; |
| 227 | } |
| 228 | |
| 229 | /* Allocate and read fragment index table */ |
| 230 | msblk->fragment_index = squashfs_read_fragment_index_table(sb, |
| 231 | le64_to_cpu(sblk->fragment_table_start), fragments); |
| 232 | if (IS_ERR(msblk->fragment_index)) { |
| 233 | err = PTR_ERR(msblk->fragment_index); |
| 234 | msblk->fragment_index = NULL; |
| 235 | goto failed_mount; |
| 236 | } |
| 237 | |
| 238 | allocate_lookup_table: |
| 239 | lookup_table_start = le64_to_cpu(sblk->lookup_table_start); |
| 240 | if (lookup_table_start == SQUASHFS_INVALID_BLK) |
| 241 | goto allocate_root; |
| 242 | |
| 243 | /* Allocate and read inode lookup table */ |
| 244 | msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, |
| 245 | lookup_table_start, msblk->inodes); |
| 246 | if (IS_ERR(msblk->inode_lookup_table)) { |
| 247 | err = PTR_ERR(msblk->inode_lookup_table); |
| 248 | msblk->inode_lookup_table = NULL; |
| 249 | goto failed_mount; |
| 250 | } |
| 251 | |
| 252 | sb->s_export_op = &squashfs_export_ops; |
| 253 | |
| 254 | allocate_root: |
| 255 | root = new_inode(sb); |
| 256 | if (!root) { |
| 257 | err = -ENOMEM; |
| 258 | goto failed_mount; |
| 259 | } |
| 260 | |
| 261 | err = squashfs_read_inode(root, root_inode); |
| 262 | if (err) { |
| 263 | iget_failed(root); |
| 264 | goto failed_mount; |
| 265 | } |
| 266 | insert_inode_hash(root); |
| 267 | |
| 268 | sb->s_root = d_alloc_root(root); |
| 269 | if (sb->s_root == NULL) { |
| 270 | ERROR("Root inode create failed\n"); |
| 271 | err = -ENOMEM; |
| 272 | iput(root); |
| 273 | goto failed_mount; |
| 274 | } |
| 275 | |
| 276 | TRACE("Leaving squashfs_fill_super\n"); |
| 277 | kfree(sblk); |
| 278 | return 0; |
| 279 | |
| 280 | failed_mount: |
| 281 | squashfs_cache_delete(msblk->block_cache); |
| 282 | squashfs_cache_delete(msblk->fragment_cache); |
| 283 | squashfs_cache_delete(msblk->read_page); |
| 284 | kfree(msblk->inode_lookup_table); |
| 285 | kfree(msblk->fragment_index); |
| 286 | kfree(msblk->id_table); |
| 287 | kfree(msblk->stream.workspace); |
| 288 | kfree(sb->s_fs_info); |
| 289 | sb->s_fs_info = NULL; |
| 290 | kfree(sblk); |
| 291 | return err; |
| 292 | |
| 293 | failure: |
| 294 | kfree(msblk->stream.workspace); |
| 295 | kfree(sb->s_fs_info); |
| 296 | sb->s_fs_info = NULL; |
| 297 | return -ENOMEM; |
| 298 | } |
| 299 | |
| 300 | |
| 301 | static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) |
| 302 | { |
| 303 | struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; |
| 304 | |
| 305 | TRACE("Entered squashfs_statfs\n"); |
| 306 | |
| 307 | buf->f_type = SQUASHFS_MAGIC; |
| 308 | buf->f_bsize = msblk->block_size; |
| 309 | buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; |
| 310 | buf->f_bfree = buf->f_bavail = 0; |
| 311 | buf->f_files = msblk->inodes; |
| 312 | buf->f_ffree = 0; |
| 313 | buf->f_namelen = SQUASHFS_NAME_LEN; |
| 314 | |
| 315 | return 0; |
| 316 | } |
| 317 | |
| 318 | |
| 319 | static int squashfs_remount(struct super_block *sb, int *flags, char *data) |
| 320 | { |
| 321 | *flags |= MS_RDONLY; |
| 322 | return 0; |
| 323 | } |
| 324 | |
| 325 | |
| 326 | static void squashfs_put_super(struct super_block *sb) |
| 327 | { |
| 328 | if (sb->s_fs_info) { |
| 329 | struct squashfs_sb_info *sbi = sb->s_fs_info; |
| 330 | squashfs_cache_delete(sbi->block_cache); |
| 331 | squashfs_cache_delete(sbi->fragment_cache); |
| 332 | squashfs_cache_delete(sbi->read_page); |
| 333 | kfree(sbi->id_table); |
| 334 | kfree(sbi->fragment_index); |
| 335 | kfree(sbi->meta_index); |
| 336 | kfree(sbi->stream.workspace); |
| 337 | kfree(sb->s_fs_info); |
| 338 | sb->s_fs_info = NULL; |
| 339 | } |
| 340 | } |
| 341 | |
| 342 | |
| 343 | static int squashfs_get_sb(struct file_system_type *fs_type, int flags, |
| 344 | const char *dev_name, void *data, |
| 345 | struct vfsmount *mnt) |
| 346 | { |
| 347 | return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super, |
| 348 | mnt); |
| 349 | } |
| 350 | |
| 351 | |
| 352 | static struct kmem_cache *squashfs_inode_cachep; |
| 353 | |
| 354 | |
| 355 | static void init_once(void *foo) |
| 356 | { |
| 357 | struct squashfs_inode_info *ei = foo; |
| 358 | |
| 359 | inode_init_once(&ei->vfs_inode); |
| 360 | } |
| 361 | |
| 362 | |
| 363 | static int __init init_inodecache(void) |
| 364 | { |
| 365 | squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", |
| 366 | sizeof(struct squashfs_inode_info), 0, |
| 367 | SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once); |
| 368 | |
| 369 | return squashfs_inode_cachep ? 0 : -ENOMEM; |
| 370 | } |
| 371 | |
| 372 | |
| 373 | static void destroy_inodecache(void) |
| 374 | { |
| 375 | kmem_cache_destroy(squashfs_inode_cachep); |
| 376 | } |
| 377 | |
| 378 | |
| 379 | static int __init init_squashfs_fs(void) |
| 380 | { |
| 381 | int err = init_inodecache(); |
| 382 | |
| 383 | if (err) |
| 384 | return err; |
| 385 | |
| 386 | err = register_filesystem(&squashfs_fs_type); |
| 387 | if (err) { |
| 388 | destroy_inodecache(); |
| 389 | return err; |
| 390 | } |
| 391 | |
Phillip Lougher | 118e1ef | 2009-03-05 00:31:12 +0000 | [diff] [blame] | 392 | printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) " |
Phillip Lougher | 0aa6661 | 2009-01-05 08:46:25 +0000 | [diff] [blame] | 393 | "Phillip Lougher\n"); |
| 394 | |
| 395 | return 0; |
| 396 | } |
| 397 | |
| 398 | |
| 399 | static void __exit exit_squashfs_fs(void) |
| 400 | { |
| 401 | unregister_filesystem(&squashfs_fs_type); |
| 402 | destroy_inodecache(); |
| 403 | } |
| 404 | |
| 405 | |
| 406 | static struct inode *squashfs_alloc_inode(struct super_block *sb) |
| 407 | { |
| 408 | struct squashfs_inode_info *ei = |
| 409 | kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); |
| 410 | |
| 411 | return ei ? &ei->vfs_inode : NULL; |
| 412 | } |
| 413 | |
| 414 | |
| 415 | static void squashfs_destroy_inode(struct inode *inode) |
| 416 | { |
| 417 | kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); |
| 418 | } |
| 419 | |
| 420 | |
| 421 | static struct file_system_type squashfs_fs_type = { |
| 422 | .owner = THIS_MODULE, |
| 423 | .name = "squashfs", |
| 424 | .get_sb = squashfs_get_sb, |
| 425 | .kill_sb = kill_block_super, |
| 426 | .fs_flags = FS_REQUIRES_DEV |
| 427 | }; |
| 428 | |
| 429 | static struct super_operations squashfs_super_ops = { |
| 430 | .alloc_inode = squashfs_alloc_inode, |
| 431 | .destroy_inode = squashfs_destroy_inode, |
| 432 | .statfs = squashfs_statfs, |
| 433 | .put_super = squashfs_put_super, |
| 434 | .remount_fs = squashfs_remount |
| 435 | }; |
| 436 | |
| 437 | module_init(init_squashfs_fs); |
| 438 | module_exit(exit_squashfs_fs); |
| 439 | MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); |
| 440 | MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>"); |
| 441 | MODULE_LICENSE("GPL"); |