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/mutex.h>
  34 #include <linux/pagemap.h>
  35 #include <linux/init.h>
  36 #include <linux/module.h>
  37 #include <linux/magic.h>
  38 #include <linux/xattr.h>
  39
  40 #include "squashfs_fs.h"
  41 #include "squashfs_fs_sb.h"
  42 #include "squashfs_fs_i.h"
  43 #include "squashfs.h"
  44 #include "decompressor.h"
  45 #include "xattr.h"
  46
  47 static struct file_system_type squashfs_fs_type;
  48 static const struct super_operations squashfs_super_ops;
  49
  50 static const struct squashfs_decompressor *supported_squashfs_filesystem(short
  51         major, short minor, short id)
  52 {
  53         const struct squashfs_decompressor *decompressor;
  54
  55         if (major < SQUASHFS_MAJOR) {
  56                 ERROR("Major/Minor mismatch, older Squashfs %d.%d "
  57                         "filesystems are unsupported\n", major, minor);
  58                 return NULL;
  59         } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
  60                 ERROR("Major/Minor mismatch, trying to mount newer "
  61                         "%d.%d filesystem\n", major, minor);
  62                 ERROR("Please update your kernel\n");
  63                 return NULL;
  64         }
  65
  66         decompressor = squashfs_lookup_decompressor(id);
  67         if (!decompressor->supported) {
  68                 ERROR("Filesystem uses \"%s\" compression. This is not "
  69                         "supported\n", decompressor->name);
  70                 return NULL;
  71         }
  72
  73         return decompressor;
  74 }
  75
  76
  77 static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
  78 {
  79         struct squashfs_sb_info *msblk;
  80         struct squashfs_super_block *sblk = NULL;
  81         char b[BDEVNAME_SIZE];
  82         struct inode *root;
  83         long long root_inode;
  84         unsigned short flags;
  85         unsigned int fragments;
  86         u64 lookup_table_start, xattr_id_table_start;
  87         int err;
  88
  89         TRACE("Entered squashfs_fill_superblock\n");
  90
  91         sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
  92         if (sb->s_fs_info == NULL) {
  93                 ERROR("Failed to allocate squashfs_sb_info\n");
  94                 return -ENOMEM;
  95         }
  96         msblk = sb->s_fs_info;
  97
  98         sblk = kzalloc(sizeof(*sblk), GFP_KERNEL);
  99         if (sblk == NULL) {
 100                 ERROR("Failed to allocate squashfs_super_block\n");
 101                 goto failure;
 102         }
 103
 104         msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE);
 105         msblk->devblksize_log2 = ffz(~msblk->devblksize);
 106
 107         mutex_init(&msblk->read_data_mutex);
 108         mutex_init(&msblk->meta_index_mutex);
 109
 110         /*
 111          * msblk->bytes_used is checked in squashfs_read_table to ensure reads
 112          * are not beyond filesystem end.  But as we're using
 113          * squashfs_read_table here to read the superblock (including the value
 114          * of bytes_used) we need to set it to an initial sensible dummy value
 115          */
 116         msblk->bytes_used = sizeof(*sblk);
 117         err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk));
 118
 119         if (err < 0) {
 120                 ERROR("unable to read squashfs_super_block\n");
 121                 goto failed_mount;
 122         }
 123
 124         err = -EINVAL;
 125
 126         /* Check it is a SQUASHFS superblock */
 127         sb->s_magic = le32_to_cpu(sblk->s_magic);
 128         if (sb->s_magic != SQUASHFS_MAGIC) {
 129                 if (!silent)
 130                         ERROR("Can't find a SQUASHFS superblock on %s\n",
 131                                                 bdevname(sb->s_bdev, b));
 132                 goto failed_mount;
 133         }
 134
 135         /* Check the MAJOR & MINOR versions and lookup compression type */
 136         msblk->decompressor = supported_squashfs_filesystem(
 137                         le16_to_cpu(sblk->s_major),
 138                         le16_to_cpu(sblk->s_minor),
 139                         le16_to_cpu(sblk->compression));
 140         if (msblk->decompressor == NULL)
 141                 goto failed_mount;
 142
 143         /* Check the filesystem does not extend beyond the end of the
 144            block device */
 145         msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
 146         if (msblk->bytes_used < 0 || msblk->bytes_used >
 147                         i_size_read(sb->s_bdev->bd_inode))
 148                 goto failed_mount;
 149
 150         /* Check block size for sanity */
 151         msblk->block_size = le32_to_cpu(sblk->block_size);
 152         if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
 153                 goto failed_mount;
 154
 155         /*
 156          * Check the system page size is not larger than the filesystem
 157          * block size (by default 128K).  This is currently not supported.
 158          */
 159         if (PAGE_CACHE_SIZE > msblk->block_size) {
 160                 ERROR("Page size > filesystem block size (%d).  This is "
 161                         "currently not supported!\n", msblk->block_size);
 162                 goto failed_mount;
 163         }
 164
 165         msblk->block_log = le16_to_cpu(sblk->block_log);
 166         if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
 167                 goto failed_mount;
 168
 169         /* Check the root inode for sanity */
 170         root_inode = le64_to_cpu(sblk->root_inode);
 171         if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
 172                 goto failed_mount;
 173
 174         msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
 175         msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
 176         msblk->inodes = le32_to_cpu(sblk->inodes);
 177         flags = le16_to_cpu(sblk->flags);
 178
 179         TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b));
 180         TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
 181                                 ? "un" : "");
 182         TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
 183                                 ? "un" : "");
 184         TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
 185         TRACE("Block size %d\n", msblk->block_size);
 186         TRACE("Number of inodes %d\n", msblk->inodes);
 187         TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments));
 188         TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
 189         TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
 190         TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
 191         TRACE("sblk->fragment_table_start %llx\n",
 192                 (u64) le64_to_cpu(sblk->fragment_table_start));
 193         TRACE("sblk->id_table_start %llx\n",
 194                 (u64) le64_to_cpu(sblk->id_table_start));
 195
 196         sb->s_maxbytes = MAX_LFS_FILESIZE;
 197         sb->s_flags |= MS_RDONLY;
 198         sb->s_op = &squashfs_super_ops;
 199
 200         err = -ENOMEM;
 201
 202         msblk->stream = squashfs_decompressor_init(msblk);
 203         if (msblk->stream == NULL)
 204                 goto failed_mount;
 205
 206         msblk->block_cache = squashfs_cache_init("metadata",
 207                         SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
 208         if (msblk->block_cache == NULL)
 209                 goto failed_mount;
 210
 211         /* Allocate read_page block */
 212         msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size);
 213         if (msblk->read_page == NULL) {
 214                 ERROR("Failed to allocate read_page block\n");
 215                 goto failed_mount;
 216         }
 217
 218         /* Allocate and read id index table */
 219         msblk->id_table = squashfs_read_id_index_table(sb,
 220                 le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids));
 221         if (IS_ERR(msblk->id_table)) {
 222                 err = PTR_ERR(msblk->id_table);
 223                 msblk->id_table = NULL;
 224                 goto failed_mount;
 225         }
 226
 227         fragments = le32_to_cpu(sblk->fragments);
 228         if (fragments == 0)
 229                 goto allocate_lookup_table;
 230
 231         msblk->fragment_cache = squashfs_cache_init("fragment",
 232                 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
 233         if (msblk->fragment_cache == NULL) {
 234                 err = -ENOMEM;
 235                 goto failed_mount;
 236         }
 237
 238         /* Allocate and read fragment index table */
 239         msblk->fragment_index = squashfs_read_fragment_index_table(sb,
 240                 le64_to_cpu(sblk->fragment_table_start), fragments);
 241         if (IS_ERR(msblk->fragment_index)) {
 242                 err = PTR_ERR(msblk->fragment_index);
 243                 msblk->fragment_index = NULL;
 244                 goto failed_mount;
 245         }
 246
 247 allocate_lookup_table:
 248         lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
 249         if (lookup_table_start == SQUASHFS_INVALID_BLK)
 250                 goto allocate_xattr_table;
 251
 252         /* Allocate and read inode lookup table */
 253         msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
 254                 lookup_table_start, msblk->inodes);
 255         if (IS_ERR(msblk->inode_lookup_table)) {
 256                 err = PTR_ERR(msblk->inode_lookup_table);
 257                 msblk->inode_lookup_table = NULL;
 258                 goto failed_mount;
 259         }
 260
 261         sb->s_export_op = &squashfs_export_ops;
 262
 263 allocate_xattr_table:
 264         sb->s_xattr = squashfs_xattr_handlers;
 265         xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
 266         if (xattr_id_table_start == SQUASHFS_INVALID_BLK)
 267                 goto allocate_root;
 268
 269         /* Allocate and read xattr id lookup table */
 270         msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
 271                 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
 272         if (IS_ERR(msblk->xattr_id_table)) {
 273                 err = PTR_ERR(msblk->xattr_id_table);
 274                 msblk->xattr_id_table = NULL;
 275                 if (err != -ENOTSUPP)
 276                         goto failed_mount;
 277         }
 278 allocate_root:
 279         root = new_inode(sb);
 280         if (!root) {
 281                 err = -ENOMEM;
 282                 goto failed_mount;
 283         }
 284
 285         err = squashfs_read_inode(root, root_inode);
 286         if (err) {
 287                 make_bad_inode(root);
 288                 iput(root);
 289                 goto failed_mount;
 290         }
 291         insert_inode_hash(root);
 292
 293         sb->s_root = d_alloc_root(root);
 294         if (sb->s_root == NULL) {
 295                 ERROR("Root inode create failed\n");
 296                 err = -ENOMEM;
 297                 iput(root);
 298                 goto failed_mount;
 299         }
 300
 301         TRACE("Leaving squashfs_fill_super\n");
 302         kfree(sblk);
 303         return 0;
 304
 305 failed_mount:
 306         squashfs_cache_delete(msblk->block_cache);
 307         squashfs_cache_delete(msblk->fragment_cache);
 308         squashfs_cache_delete(msblk->read_page);
 309         squashfs_decompressor_free(msblk, msblk->stream);
 310         kfree(msblk->inode_lookup_table);
 311         kfree(msblk->fragment_index);
 312         kfree(msblk->id_table);
 313         kfree(msblk->xattr_id_table);
 314         kfree(sb->s_fs_info);
 315         sb->s_fs_info = NULL;
 316         kfree(sblk);
 317         return err;
 318
 319 failure:
 320         kfree(sb->s_fs_info);
 321         sb->s_fs_info = NULL;
 322         return -ENOMEM;
 323 }
 324
 325
 326 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 327 {
 328         struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
 329         u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
 330
 331         TRACE("Entered squashfs_statfs\n");
 332
 333         buf->f_type = SQUASHFS_MAGIC;
 334         buf->f_bsize = msblk->block_size;
 335         buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
 336         buf->f_bfree = buf->f_bavail = 0;
 337         buf->f_files = msblk->inodes;
 338         buf->f_ffree = 0;
 339         buf->f_namelen = SQUASHFS_NAME_LEN;
 340         buf->f_fsid.val[0] = (u32)id;
 341         buf->f_fsid.val[1] = (u32)(id >> 32);
 342
 343         return 0;
 344 }
 345
 346
 347 static int squashfs_remount(struct super_block *sb, int *flags, char *data)
 348 {
 349         *flags |= MS_RDONLY;
 350         return 0;
 351 }
 352
 353
 354 static void squashfs_put_super(struct super_block *sb)
 355 {
 356         if (sb->s_fs_info) {
 357                 struct squashfs_sb_info *sbi = sb->s_fs_info;
 358                 squashfs_cache_delete(sbi->block_cache);
 359                 squashfs_cache_delete(sbi->fragment_cache);
 360                 squashfs_cache_delete(sbi->read_page);
 361                 squashfs_decompressor_free(sbi, sbi->stream);
 362                 kfree(sbi->id_table);
 363                 kfree(sbi->fragment_index);
 364                 kfree(sbi->meta_index);
 365                 kfree(sbi->inode_lookup_table);
 366                 kfree(sbi->xattr_id_table);
 367                 kfree(sb->s_fs_info);
 368                 sb->s_fs_info = NULL;
 369         }
 370 }
 371
 372
 373 static struct dentry *squashfs_mount(struct file_system_type *fs_type, int flags,
 374                                 const char *dev_name, void *data)
 375 {
 376         return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super);
 377 }
 378
 379
 380 static struct kmem_cache *squashfs_inode_cachep;
 381
 382
 383 static void init_once(void *foo)
 384 {
 385         struct squashfs_inode_info *ei = foo;
 386
 387         inode_init_once(&ei->vfs_inode);
 388 }
 389
 390
 391 static int __init init_inodecache(void)
 392 {
 393         squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
 394                 sizeof(struct squashfs_inode_info), 0,
 395                 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once);
 396
 397         return squashfs_inode_cachep ? 0 : -ENOMEM;
 398 }
 399
 400
 401 static void destroy_inodecache(void)
 402 {
 403         kmem_cache_destroy(squashfs_inode_cachep);
 404 }
 405
 406
 407 static int __init init_squashfs_fs(void)
 408 {
 409         int err = init_inodecache();
 410
 411         if (err)
 412                 return err;
 413
 414         err = register_filesystem(&squashfs_fs_type);
 415         if (err) {
 416                 destroy_inodecache();
 417                 return err;
 418         }
 419
 420         printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) "
 421                 "Phillip Lougher\n");
 422
 423         return 0;
 424 }
 425
 426
 427 static void __exit exit_squashfs_fs(void)
 428 {
 429         unregister_filesystem(&squashfs_fs_type);
 430         destroy_inodecache();
 431 }
 432
 433
 434 static struct inode *squashfs_alloc_inode(struct super_block *sb)
 435 {
 436         struct squashfs_inode_info *ei =
 437                 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
 438
 439         return ei ? &ei->vfs_inode : NULL;
 440 }
 441
 442
 443 static void squashfs_i_callback(struct rcu_head *head)
 444 {
 445         struct inode *inode = container_of(head, struct inode, i_rcu);
 446         INIT_LIST_HEAD(&inode->i_dentry);
 447         kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
 448 }
 449
 450 static void squashfs_destroy_inode(struct inode *inode)
 451 {
 452         call_rcu(&inode->i_rcu, squashfs_i_callback);
 453 }
 454
 455
 456 static struct file_system_type squashfs_fs_type = {
 457         .owner = THIS_MODULE,
 458         .name = "squashfs",
 459         .mount = squashfs_mount,
 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");