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
  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@lougher.demon.co.uk>");
 440 MODULE_LICENSE("GPL");