fs/squashfs/super.c

   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");