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         lock_kernel();
  91
  92         TRACE("Entered squashfs_fill_superblock\n");
  93
  94         sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
  95         if (sb->s_fs_info == NULL) {
  96                 ERROR("Failed to allocate squashfs_sb_info\n");
  97                 unlock_kernel();
  98                 return -ENOMEM;
  99         }
 100         msblk = sb->s_fs_info;
 101
 102         sblk = kzalloc(sizeof(*sblk), GFP_KERNEL);
 103         if (sblk == NULL) {
 104                 ERROR("Failed to allocate squashfs_super_block\n");
 105                 goto failure;
 106         }
 107
 108         msblk->devblksize = sb_min_blocksize(sb, BLOCK_SIZE);
 109         msblk->devblksize_log2 = ffz(~msblk->devblksize);
 110
 111         mutex_init(&msblk->read_data_mutex);
 112         mutex_init(&msblk->meta_index_mutex);
 113
 114         /*
 115          * msblk->bytes_used is checked in squashfs_read_table to ensure reads
 116          * are not beyond filesystem end.  But as we're using
 117          * squashfs_read_table here to read the superblock (including the value
 118          * of bytes_used) we need to set it to an initial sensible dummy value
 119          */
 120         msblk->bytes_used = sizeof(*sblk);
 121         err = squashfs_read_table(sb, sblk, SQUASHFS_START, sizeof(*sblk));
 122
 123         if (err < 0) {
 124                 ERROR("unable to read squashfs_super_block\n");
 125                 goto failed_mount;
 126         }
 127
 128         err = -EINVAL;
 129
 130         /* Check it is a SQUASHFS superblock */
 131         sb->s_magic = le32_to_cpu(sblk->s_magic);
 132         if (sb->s_magic != SQUASHFS_MAGIC) {
 133                 if (!silent)
 134                         ERROR("Can't find a SQUASHFS superblock on %s\n",
 135                                                 bdevname(sb->s_bdev, b));
 136                 goto failed_mount;
 137         }
 138
 139         /* Check the MAJOR & MINOR versions and lookup compression type */
 140         msblk->decompressor = supported_squashfs_filesystem(
 141                         le16_to_cpu(sblk->s_major),
 142                         le16_to_cpu(sblk->s_minor),
 143                         le16_to_cpu(sblk->compression));
 144         if (msblk->decompressor == NULL)
 145                 goto failed_mount;
 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         /*
 160          * Check the system page size is not larger than the filesystem
 161          * block size (by default 128K).  This is currently not supported.
 162          */
 163         if (PAGE_CACHE_SIZE > msblk->block_size) {
 164                 ERROR("Page size > filesystem block size (%d).  This is "
 165                         "currently not supported!\n", msblk->block_size);
 166                 goto failed_mount;
 167         }
 168
 169         msblk->block_log = le16_to_cpu(sblk->block_log);
 170         if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
 171                 goto failed_mount;
 172
 173         /* Check the root inode for sanity */
 174         root_inode = le64_to_cpu(sblk->root_inode);
 175         if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
 176                 goto failed_mount;
 177
 178         msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
 179         msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
 180         msblk->inodes = le32_to_cpu(sblk->inodes);
 181         flags = le16_to_cpu(sblk->flags);
 182
 183         TRACE("Found valid superblock on %s\n", bdevname(sb->s_bdev, b));
 184         TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
 185                                 ? "un" : "");
 186         TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
 187                                 ? "un" : "");
 188         TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
 189         TRACE("Block size %d\n", msblk->block_size);
 190         TRACE("Number of inodes %d\n", msblk->inodes);
 191         TRACE("Number of fragments %d\n", le32_to_cpu(sblk->fragments));
 192         TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids));
 193         TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
 194         TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
 195         TRACE("sblk->fragment_table_start %llx\n",
 196                 (u64) le64_to_cpu(sblk->fragment_table_start));
 197         TRACE("sblk->id_table_start %llx\n",
 198                 (u64) le64_to_cpu(sblk->id_table_start));
 199
 200         sb->s_maxbytes = MAX_LFS_FILESIZE;
 201         sb->s_flags |= MS_RDONLY;
 202         sb->s_op = &squashfs_super_ops;
 203
 204         err = -ENOMEM;
 205
 206         msblk->stream = squashfs_decompressor_init(msblk);
 207         if (msblk->stream == NULL)
 208                 goto failed_mount;
 209
 210         msblk->block_cache = squashfs_cache_init("metadata",
 211                         SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
 212         if (msblk->block_cache == NULL)
 213                 goto failed_mount;
 214
 215         /* Allocate read_page block */
 216         msblk->read_page = squashfs_cache_init("data", 1, msblk->block_size);
 217         if (msblk->read_page == NULL) {
 218                 ERROR("Failed to allocate read_page block\n");
 219                 goto failed_mount;
 220         }
 221
 222         /* Allocate and read id index table */
 223         msblk->id_table = squashfs_read_id_index_table(sb,
 224                 le64_to_cpu(sblk->id_table_start), le16_to_cpu(sblk->no_ids));
 225         if (IS_ERR(msblk->id_table)) {
 226                 err = PTR_ERR(msblk->id_table);
 227                 msblk->id_table = NULL;
 228                 goto failed_mount;
 229         }
 230
 231         fragments = le32_to_cpu(sblk->fragments);
 232         if (fragments == 0)
 233                 goto allocate_lookup_table;
 234
 235         msblk->fragment_cache = squashfs_cache_init("fragment",
 236                 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
 237         if (msblk->fragment_cache == NULL) {
 238                 err = -ENOMEM;
 239                 goto failed_mount;
 240         }
 241
 242         /* Allocate and read fragment index table */
 243         msblk->fragment_index = squashfs_read_fragment_index_table(sb,
 244                 le64_to_cpu(sblk->fragment_table_start), fragments);
 245         if (IS_ERR(msblk->fragment_index)) {
 246                 err = PTR_ERR(msblk->fragment_index);
 247                 msblk->fragment_index = NULL;
 248                 goto failed_mount;
 249         }
 250
 251 allocate_lookup_table:
 252         lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
 253         if (lookup_table_start == SQUASHFS_INVALID_BLK)
 254                 goto allocate_xattr_table;
 255
 256         /* Allocate and read inode lookup table */
 257         msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
 258                 lookup_table_start, msblk->inodes);
 259         if (IS_ERR(msblk->inode_lookup_table)) {
 260                 err = PTR_ERR(msblk->inode_lookup_table);
 261                 msblk->inode_lookup_table = NULL;
 262                 goto failed_mount;
 263         }
 264
 265         sb->s_export_op = &squashfs_export_ops;
 266
 267 allocate_xattr_table:
 268         sb->s_xattr = squashfs_xattr_handlers;
 269         xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
 270         if (xattr_id_table_start == SQUASHFS_INVALID_BLK)
 271                 goto allocate_root;
 272
 273         /* Allocate and read xattr id lookup table */
 274         msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
 275                 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
 276         if (IS_ERR(msblk->xattr_id_table)) {
 277                 err = PTR_ERR(msblk->xattr_id_table);
 278                 msblk->xattr_id_table = NULL;
 279                 if (err != -ENOTSUPP)
 280                         goto failed_mount;
 281         }
 282 allocate_root:
 283         root = new_inode(sb);
 284         if (!root) {
 285                 err = -ENOMEM;
 286                 goto failed_mount;
 287         }
 288
 289         err = squashfs_read_inode(root, root_inode);
 290         if (err) {
 291                 make_bad_inode(root);
 292                 iput(root);
 293                 goto failed_mount;
 294         }
 295         insert_inode_hash(root);
 296
 297         sb->s_root = d_alloc_root(root);
 298         if (sb->s_root == NULL) {
 299                 ERROR("Root inode create failed\n");
 300                 err = -ENOMEM;
 301                 iput(root);
 302                 goto failed_mount;
 303         }
 304
 305         TRACE("Leaving squashfs_fill_super\n");
 306         kfree(sblk);
 307         unlock_kernel();
 308         return 0;
 309
 310 failed_mount:
 311         squashfs_cache_delete(msblk->block_cache);
 312         squashfs_cache_delete(msblk->fragment_cache);
 313         squashfs_cache_delete(msblk->read_page);
 314         squashfs_decompressor_free(msblk, msblk->stream);
 315         kfree(msblk->inode_lookup_table);
 316         kfree(msblk->fragment_index);
 317         kfree(msblk->id_table);
 318         kfree(msblk->xattr_id_table);
 319         kfree(sb->s_fs_info);
 320         sb->s_fs_info = NULL;
 321         kfree(sblk);
 322         unlock_kernel();
 323         return err;
 324
 325 failure:
 326         kfree(sb->s_fs_info);
 327         sb->s_fs_info = NULL;
 328         unlock_kernel();
 329         return -ENOMEM;
 330 }
 331
 332
 333 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 334 {
 335         struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
 336         u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
 337
 338         TRACE("Entered squashfs_statfs\n");
 339
 340         buf->f_type = SQUASHFS_MAGIC;
 341         buf->f_bsize = msblk->block_size;
 342         buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
 343         buf->f_bfree = buf->f_bavail = 0;
 344         buf->f_files = msblk->inodes;
 345         buf->f_ffree = 0;
 346         buf->f_namelen = SQUASHFS_NAME_LEN;
 347         buf->f_fsid.val[0] = (u32)id;
 348         buf->f_fsid.val[1] = (u32)(id >> 32);
 349
 350         return 0;
 351 }
 352
 353
 354 static int squashfs_remount(struct super_block *sb, int *flags, char *data)
 355 {
 356         *flags |= MS_RDONLY;
 357         return 0;
 358 }
 359
 360
 361 static void squashfs_put_super(struct super_block *sb)
 362 {
 363         lock_kernel();
 364
 365         if (sb->s_fs_info) {
 366                 struct squashfs_sb_info *sbi = sb->s_fs_info;
 367                 squashfs_cache_delete(sbi->block_cache);
 368                 squashfs_cache_delete(sbi->fragment_cache);
 369                 squashfs_cache_delete(sbi->read_page);
 370                 squashfs_decompressor_free(sbi, sbi->stream);
 371                 kfree(sbi->id_table);
 372                 kfree(sbi->fragment_index);
 373                 kfree(sbi->meta_index);
 374                 kfree(sbi->inode_lookup_table);
 375                 kfree(sbi->xattr_id_table);
 376                 kfree(sb->s_fs_info);
 377                 sb->s_fs_info = NULL;
 378         }
 379
 380         unlock_kernel();
 381 }
 382
 383
 384 static int squashfs_get_sb(struct file_system_type *fs_type, int flags,
 385                                 const char *dev_name, void *data,
 386                                 struct vfsmount *mnt)
 387 {
 388         return get_sb_bdev(fs_type, flags, dev_name, data, squashfs_fill_super,
 389                                 mnt);
 390 }
 391
 392
 393 static struct kmem_cache *squashfs_inode_cachep;
 394
 395
 396 static void init_once(void *foo)
 397 {
 398         struct squashfs_inode_info *ei = foo;
 399
 400         inode_init_once(&ei->vfs_inode);
 401 }
 402
 403
 404 static int __init init_inodecache(void)
 405 {
 406         squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
 407                 sizeof(struct squashfs_inode_info), 0,
 408                 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, init_once);
 409
 410         return squashfs_inode_cachep ? 0 : -ENOMEM;
 411 }
 412
 413
 414 static void destroy_inodecache(void)
 415 {
 416         kmem_cache_destroy(squashfs_inode_cachep);
 417 }
 418
 419
 420 static int __init init_squashfs_fs(void)
 421 {
 422         int err = init_inodecache();
 423
 424         if (err)
 425                 return err;
 426
 427         err = register_filesystem(&squashfs_fs_type);
 428         if (err) {
 429                 destroy_inodecache();
 430                 return err;
 431         }
 432
 433         printk(KERN_INFO "squashfs: version 4.0 (2009/01/31) "
 434                 "Phillip Lougher\n");
 435
 436         return 0;
 437 }
 438
 439
 440 static void __exit exit_squashfs_fs(void)
 441 {
 442         unregister_filesystem(&squashfs_fs_type);
 443         destroy_inodecache();
 444 }
 445
 446
 447 static struct inode *squashfs_alloc_inode(struct super_block *sb)
 448 {
 449         struct squashfs_inode_info *ei =
 450                 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL);
 451
 452         return ei ? &ei->vfs_inode : NULL;
 453 }
 454
 455
 456 static void squashfs_destroy_inode(struct inode *inode)
 457 {
 458         kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
 459 }
 460
 461
 462 static struct file_system_type squashfs_fs_type = {
 463         .owner = THIS_MODULE,
 464         .name = "squashfs",
 465         .get_sb = squashfs_get_sb,
 466         .kill_sb = kill_block_super,
 467         .fs_flags = FS_REQUIRES_DEV
 468 };
 469
 470 static const struct super_operations squashfs_super_ops = {
 471         .alloc_inode = squashfs_alloc_inode,
 472         .destroy_inode = squashfs_destroy_inode,
 473         .statfs = squashfs_statfs,
 474         .put_super = squashfs_put_super,
 475         .remount_fs = squashfs_remount
 476 };
 477
 478 module_init(init_squashfs_fs);
 479 module_exit(exit_squashfs_fs);
 480 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
 481 MODULE_AUTHOR("Phillip Lougher <phillip@lougher.demon.co.uk>");
 482 MODULE_LICENSE("GPL");