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/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         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
 392         printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) "
 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");