fs/squashfs/super.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Squashfs - a compressed read only filesystem for Linux
   4  *
   5  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
   6  * Phillip Lougher <phillip@squashfs.org.uk>
   7  *
   8  * super.c
   9  */
  10
  11 /*
  12  * This file implements code to read the superblock, read and initialise
  13  * in-memory structures at mount time, and all the VFS glue code to register
  14  * the filesystem.
  15  */
  16
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/fs.h>
  21 #include <linux/fs_context.h>
  22 #include <linux/fs_parser.h>
  23 #include <linux/vfs.h>
  24 #include <linux/slab.h>
  25 #include <linux/mutex.h>
  26 #include <linux/seq_file.h>
  27 #include <linux/pagemap.h>
  28 #include <linux/init.h>
  29 #include <linux/module.h>
  30 #include <linux/magic.h>
  31 #include <linux/xattr.h>
  32
  33 #include "squashfs_fs.h"
  34 #include "squashfs_fs_sb.h"
  35 #include "squashfs_fs_i.h"
  36 #include "squashfs.h"
  37 #include "decompressor.h"
  38 #include "xattr.h"
  39
  40 static struct file_system_type squashfs_fs_type;
  41 static const struct super_operations squashfs_super_ops;
  42
  43 enum Opt_errors {
  44         Opt_errors_continue,
  45         Opt_errors_panic,
  46 };
  47
  48 enum squashfs_param {
  49         Opt_errors,
  50         Opt_threads,
  51 };
  52
  53 struct squashfs_mount_opts {
  54         enum Opt_errors errors;
  55         const struct squashfs_decompressor_thread_ops *thread_ops;
  56         int thread_num;
  57 };
  58
  59 static const struct constant_table squashfs_param_errors[] = {
  60         {"continue",   Opt_errors_continue },
  61         {"panic",      Opt_errors_panic },
  62         {}
  63 };
  64
  65 static const struct fs_parameter_spec squashfs_fs_parameters[] = {
  66         fsparam_enum("errors", Opt_errors, squashfs_param_errors),
  67         fsparam_string("threads", Opt_threads),
  68         {}
  69 };
  70
  71
  72 static int squashfs_parse_param_threads_str(const char *str, struct squashfs_mount_opts *opts)
  73 {
  74 #ifdef CONFIG_SQUASHFS_CHOICE_DECOMP_BY_MOUNT
  75         if (strcmp(str, "single") == 0) {
  76                 opts->thread_ops = &squashfs_decompressor_single;
  77                 return 0;
  78         }
  79         if (strcmp(str, "multi") == 0) {
  80                 opts->thread_ops = &squashfs_decompressor_multi;
  81                 return 0;
  82         }
  83         if (strcmp(str, "percpu") == 0) {
  84                 opts->thread_ops = &squashfs_decompressor_percpu;
  85                 return 0;
  86         }
  87 #endif
  88         return -EINVAL;
  89 }
  90
  91 static int squashfs_parse_param_threads_num(const char *str, struct squashfs_mount_opts *opts)
  92 {
  93 #ifdef CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS
  94         int ret;
  95         unsigned long num;
  96
  97         ret = kstrtoul(str, 0, &num);
  98         if (ret != 0)
  99                 return -EINVAL;
 100         if (num > 1) {
 101                 opts->thread_ops = &squashfs_decompressor_multi;
 102                 if (num > opts->thread_ops->max_decompressors())
 103                         return -EINVAL;
 104                 opts->thread_num = (int)num;
 105                 return 0;
 106         }
 107 #ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
 108         if (num == 1) {
 109                 opts->thread_ops = &squashfs_decompressor_single;
 110                 opts->thread_num = 1;
 111                 return 0;
 112         }
 113 #endif
 114 #endif /* !CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS */
 115         return -EINVAL;
 116 }
 117
 118 static int squashfs_parse_param_threads(const char *str, struct squashfs_mount_opts *opts)
 119 {
 120         int ret = squashfs_parse_param_threads_str(str, opts);
 121
 122         if (ret == 0)
 123                 return ret;
 124         return squashfs_parse_param_threads_num(str, opts);
 125 }
 126
 127 static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 128 {
 129         struct squashfs_mount_opts *opts = fc->fs_private;
 130         struct fs_parse_result result;
 131         int opt;
 132
 133         opt = fs_parse(fc, squashfs_fs_parameters, param, &result);
 134         if (opt < 0)
 135                 return opt;
 136
 137         switch (opt) {
 138         case Opt_errors:
 139                 opts->errors = result.uint_32;
 140                 break;
 141         case Opt_threads:
 142                 if (squashfs_parse_param_threads(param->string, opts) != 0)
 143                         return -EINVAL;
 144                 break;
 145         default:
 146                 return -EINVAL;
 147         }
 148
 149         return 0;
 150 }
 151
 152 static const struct squashfs_decompressor *supported_squashfs_filesystem(
 153         struct fs_context *fc,
 154         short major, short minor, short id)
 155 {
 156         const struct squashfs_decompressor *decompressor;
 157
 158         if (major < SQUASHFS_MAJOR) {
 159                 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
 160                        "filesystems are unsupported", major, minor);
 161                 return NULL;
 162         } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
 163                 errorf(fc, "Major/Minor mismatch, trying to mount newer "
 164                        "%d.%d filesystem", major, minor);
 165                 errorf(fc, "Please update your kernel");
 166                 return NULL;
 167         }
 168
 169         decompressor = squashfs_lookup_decompressor(id);
 170         if (!decompressor->supported) {
 171                 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
 172                        decompressor->name);
 173                 return NULL;
 174         }
 175
 176         return decompressor;
 177 }
 178
 179
 180 static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 181 {
 182         struct squashfs_mount_opts *opts = fc->fs_private;
 183         struct squashfs_sb_info *msblk;
 184         struct squashfs_super_block *sblk = NULL;
 185         struct inode *root;
 186         long long root_inode;
 187         unsigned short flags;
 188         unsigned int fragments;
 189         u64 lookup_table_start, xattr_id_table_start, next_table;
 190         int err;
 191
 192         TRACE("Entered squashfs_fill_superblock\n");
 193
 194         sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
 195         if (sb->s_fs_info == NULL) {
 196                 ERROR("Failed to allocate squashfs_sb_info\n");
 197                 return -ENOMEM;
 198         }
 199         msblk = sb->s_fs_info;
 200         msblk->thread_ops = opts->thread_ops;
 201
 202         msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
 203
 204         msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
 205         msblk->devblksize_log2 = ffz(~msblk->devblksize);
 206
 207         mutex_init(&msblk->meta_index_mutex);
 208
 209         /*
 210          * msblk->bytes_used is checked in squashfs_read_table to ensure reads
 211          * are not beyond filesystem end.  But as we're using
 212          * squashfs_read_table here to read the superblock (including the value
 213          * of bytes_used) we need to set it to an initial sensible dummy value
 214          */
 215         msblk->bytes_used = sizeof(*sblk);
 216         sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
 217
 218         if (IS_ERR(sblk)) {
 219                 errorf(fc, "unable to read squashfs_super_block");
 220                 err = PTR_ERR(sblk);
 221                 sblk = NULL;
 222                 goto failed_mount;
 223         }
 224
 225         err = -EINVAL;
 226
 227         /* Check it is a SQUASHFS superblock */
 228         sb->s_magic = le32_to_cpu(sblk->s_magic);
 229         if (sb->s_magic != SQUASHFS_MAGIC) {
 230                 if (!(fc->sb_flags & SB_SILENT))
 231                         errorf(fc, "Can't find a SQUASHFS superblock on %pg",
 232                                sb->s_bdev);
 233                 goto failed_mount;
 234         }
 235
 236         if (opts->thread_num == 0) {
 237                 msblk->max_thread_num = msblk->thread_ops->max_decompressors();
 238         } else {
 239                 msblk->max_thread_num = opts->thread_num;
 240         }
 241
 242         /* Check the MAJOR & MINOR versions and lookup compression type */
 243         msblk->decompressor = supported_squashfs_filesystem(
 244                         fc,
 245                         le16_to_cpu(sblk->s_major),
 246                         le16_to_cpu(sblk->s_minor),
 247                         le16_to_cpu(sblk->compression));
 248         if (msblk->decompressor == NULL)
 249                 goto failed_mount;
 250
 251         /* Check the filesystem does not extend beyond the end of the
 252            block device */
 253         msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
 254         if (msblk->bytes_used < 0 ||
 255             msblk->bytes_used > bdev_nr_bytes(sb->s_bdev))
 256                 goto failed_mount;
 257
 258         /* Check block size for sanity */
 259         msblk->block_size = le32_to_cpu(sblk->block_size);
 260         if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
 261                 goto insanity;
 262
 263         /*
 264          * Check the system page size is not larger than the filesystem
 265          * block size (by default 128K).  This is currently not supported.
 266          */
 267         if (PAGE_SIZE > msblk->block_size) {
 268                 errorf(fc, "Page size > filesystem block size (%d).  This is "
 269                        "currently not supported!", msblk->block_size);
 270                 goto failed_mount;
 271         }
 272
 273         /* Check block log for sanity */
 274         msblk->block_log = le16_to_cpu(sblk->block_log);
 275         if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
 276                 goto failed_mount;
 277
 278         /* Check that block_size and block_log match */
 279         if (msblk->block_size != (1 << msblk->block_log))
 280                 goto insanity;
 281
 282         /* Check the root inode for sanity */
 283         root_inode = le64_to_cpu(sblk->root_inode);
 284         if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
 285                 goto insanity;
 286
 287         msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
 288         msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
 289         msblk->inodes = le32_to_cpu(sblk->inodes);
 290         msblk->fragments = le32_to_cpu(sblk->fragments);
 291         msblk->ids = le16_to_cpu(sblk->no_ids);
 292         flags = le16_to_cpu(sblk->flags);
 293
 294         TRACE("Found valid superblock on %pg\n", sb->s_bdev);
 295         TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
 296                                 ? "un" : "");
 297         TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
 298                                 ? "un" : "");
 299         TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
 300         TRACE("Block size %d\n", msblk->block_size);
 301         TRACE("Number of inodes %d\n", msblk->inodes);
 302         TRACE("Number of fragments %d\n", msblk->fragments);
 303         TRACE("Number of ids %d\n", msblk->ids);
 304         TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
 305         TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
 306         TRACE("sblk->fragment_table_start %llx\n",
 307                 (u64) le64_to_cpu(sblk->fragment_table_start));
 308         TRACE("sblk->id_table_start %llx\n",
 309                 (u64) le64_to_cpu(sblk->id_table_start));
 310
 311         sb->s_maxbytes = MAX_LFS_FILESIZE;
 312         sb->s_time_min = 0;
 313         sb->s_time_max = U32_MAX;
 314         sb->s_flags |= SB_RDONLY;
 315         sb->s_op = &squashfs_super_ops;
 316
 317         err = -ENOMEM;
 318
 319         msblk->block_cache = squashfs_cache_init("metadata",
 320                         SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
 321         if (msblk->block_cache == NULL)
 322                 goto failed_mount;
 323
 324         /* Allocate read_page block */
 325         msblk->read_page = squashfs_cache_init("data",
 326                 msblk->max_thread_num, msblk->block_size);
 327         if (msblk->read_page == NULL) {
 328                 errorf(fc, "Failed to allocate read_page block");
 329                 goto failed_mount;
 330         }
 331
 332         if (msblk->devblksize == PAGE_SIZE) {
 333                 struct inode *cache = new_inode(sb);
 334
 335                 if (cache == NULL)
 336                         goto failed_mount;
 337
 338                 set_nlink(cache, 1);
 339                 cache->i_size = OFFSET_MAX;
 340                 mapping_set_gfp_mask(cache->i_mapping, GFP_NOFS);
 341
 342                 msblk->cache_mapping = cache->i_mapping;
 343         }
 344
 345         msblk->stream = squashfs_decompressor_setup(sb, flags);
 346         if (IS_ERR(msblk->stream)) {
 347                 err = PTR_ERR(msblk->stream);
 348                 msblk->stream = NULL;
 349                 goto insanity;
 350         }
 351
 352         /* Handle xattrs */
 353         sb->s_xattr = squashfs_xattr_handlers;
 354         xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
 355         if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
 356                 next_table = msblk->bytes_used;
 357                 goto allocate_id_index_table;
 358         }
 359
 360         /* Allocate and read xattr id lookup table */
 361         msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
 362                 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
 363         if (IS_ERR(msblk->xattr_id_table)) {
 364                 errorf(fc, "unable to read xattr id index table");
 365                 err = PTR_ERR(msblk->xattr_id_table);
 366                 msblk->xattr_id_table = NULL;
 367                 if (err != -ENOTSUPP)
 368                         goto failed_mount;
 369         }
 370         next_table = msblk->xattr_table;
 371
 372 allocate_id_index_table:
 373         /* Allocate and read id index table */
 374         msblk->id_table = squashfs_read_id_index_table(sb,
 375                 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
 376         if (IS_ERR(msblk->id_table)) {
 377                 errorf(fc, "unable to read id index table");
 378                 err = PTR_ERR(msblk->id_table);
 379                 msblk->id_table = NULL;
 380                 goto failed_mount;
 381         }
 382         next_table = le64_to_cpu(msblk->id_table[0]);
 383
 384         /* Handle inode lookup table */
 385         lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
 386         if (lookup_table_start == SQUASHFS_INVALID_BLK)
 387                 goto handle_fragments;
 388
 389         /* Allocate and read inode lookup table */
 390         msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
 391                 lookup_table_start, next_table, msblk->inodes);
 392         if (IS_ERR(msblk->inode_lookup_table)) {
 393                 errorf(fc, "unable to read inode lookup table");
 394                 err = PTR_ERR(msblk->inode_lookup_table);
 395                 msblk->inode_lookup_table = NULL;
 396                 goto failed_mount;
 397         }
 398         next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
 399
 400         sb->s_export_op = &squashfs_export_ops;
 401
 402 handle_fragments:
 403         fragments = msblk->fragments;
 404         if (fragments == 0)
 405                 goto check_directory_table;
 406
 407         msblk->fragment_cache = squashfs_cache_init("fragment",
 408                 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
 409         if (msblk->fragment_cache == NULL) {
 410                 err = -ENOMEM;
 411                 goto failed_mount;
 412         }
 413
 414         /* Allocate and read fragment index table */
 415         msblk->fragment_index = squashfs_read_fragment_index_table(sb,
 416                 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
 417         if (IS_ERR(msblk->fragment_index)) {
 418                 errorf(fc, "unable to read fragment index table");
 419                 err = PTR_ERR(msblk->fragment_index);
 420                 msblk->fragment_index = NULL;
 421                 goto failed_mount;
 422         }
 423         next_table = le64_to_cpu(msblk->fragment_index[0]);
 424
 425 check_directory_table:
 426         /* Sanity check directory_table */
 427         if (msblk->directory_table > next_table) {
 428                 err = -EINVAL;
 429                 goto insanity;
 430         }
 431
 432         /* Sanity check inode_table */
 433         if (msblk->inode_table >= msblk->directory_table) {
 434                 err = -EINVAL;
 435                 goto insanity;
 436         }
 437
 438         /* allocate root */
 439         root = new_inode(sb);
 440         if (!root) {
 441                 err = -ENOMEM;
 442                 goto failed_mount;
 443         }
 444
 445         err = squashfs_read_inode(root, root_inode);
 446         if (err) {
 447                 make_bad_inode(root);
 448                 iput(root);
 449                 goto failed_mount;
 450         }
 451         insert_inode_hash(root);
 452
 453         sb->s_root = d_make_root(root);
 454         if (sb->s_root == NULL) {
 455                 ERROR("Root inode create failed\n");
 456                 err = -ENOMEM;
 457                 goto failed_mount;
 458         }
 459
 460         TRACE("Leaving squashfs_fill_super\n");
 461         kfree(sblk);
 462         return 0;
 463
 464 insanity:
 465         errorf(fc, "squashfs image failed sanity check");
 466 failed_mount:
 467         squashfs_cache_delete(msblk->block_cache);
 468         squashfs_cache_delete(msblk->fragment_cache);
 469         squashfs_cache_delete(msblk->read_page);
 470         if (msblk->cache_mapping)
 471                 iput(msblk->cache_mapping->host);
 472         msblk->thread_ops->destroy(msblk);
 473         kfree(msblk->inode_lookup_table);
 474         kfree(msblk->fragment_index);
 475         kfree(msblk->id_table);
 476         kfree(msblk->xattr_id_table);
 477         kfree(sb->s_fs_info);
 478         sb->s_fs_info = NULL;
 479         kfree(sblk);
 480         return err;
 481 }
 482
 483 static int squashfs_get_tree(struct fs_context *fc)
 484 {
 485         return get_tree_bdev(fc, squashfs_fill_super);
 486 }
 487
 488 static int squashfs_reconfigure(struct fs_context *fc)
 489 {
 490         struct super_block *sb = fc->root->d_sb;
 491         struct squashfs_sb_info *msblk = sb->s_fs_info;
 492         struct squashfs_mount_opts *opts = fc->fs_private;
 493
 494         sync_filesystem(fc->root->d_sb);
 495         fc->sb_flags |= SB_RDONLY;
 496
 497         msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
 498
 499         return 0;
 500 }
 501
 502 static void squashfs_free_fs_context(struct fs_context *fc)
 503 {
 504         kfree(fc->fs_private);
 505 }
 506
 507 static const struct fs_context_operations squashfs_context_ops = {
 508         .get_tree       = squashfs_get_tree,
 509         .free           = squashfs_free_fs_context,
 510         .parse_param    = squashfs_parse_param,
 511         .reconfigure    = squashfs_reconfigure,
 512 };
 513
 514 static int squashfs_show_options(struct seq_file *s, struct dentry *root)
 515 {
 516         struct super_block *sb = root->d_sb;
 517         struct squashfs_sb_info *msblk = sb->s_fs_info;
 518
 519         if (msblk->panic_on_errors)
 520                 seq_puts(s, ",errors=panic");
 521         else
 522                 seq_puts(s, ",errors=continue");
 523
 524 #ifdef CONFIG_SQUASHFS_CHOICE_DECOMP_BY_MOUNT
 525         if (msblk->thread_ops == &squashfs_decompressor_single) {
 526                 seq_puts(s, ",threads=single");
 527                 return 0;
 528         }
 529         if (msblk->thread_ops == &squashfs_decompressor_percpu) {
 530                 seq_puts(s, ",threads=percpu");
 531                 return 0;
 532         }
 533 #endif
 534 #ifdef CONFIG_SQUASHFS_MOUNT_DECOMP_THREADS
 535         seq_printf(s, ",threads=%d", msblk->max_thread_num);
 536 #endif
 537         return 0;
 538 }
 539
 540 static int squashfs_init_fs_context(struct fs_context *fc)
 541 {
 542         struct squashfs_mount_opts *opts;
 543
 544         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 545         if (!opts)
 546                 return -ENOMEM;
 547
 548 #ifdef CONFIG_SQUASHFS_DECOMP_SINGLE
 549         opts->thread_ops = &squashfs_decompressor_single;
 550 #elif defined(CONFIG_SQUASHFS_DECOMP_MULTI)
 551         opts->thread_ops = &squashfs_decompressor_multi;
 552 #elif defined(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU)
 553         opts->thread_ops = &squashfs_decompressor_percpu;
 554 #else
 555 #error "fail: unknown squashfs decompression thread mode?"
 556 #endif
 557         opts->thread_num = 0;
 558         fc->fs_private = opts;
 559         fc->ops = &squashfs_context_ops;
 560         return 0;
 561 }
 562
 563 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 564 {
 565         struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
 566         u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
 567
 568         TRACE("Entered squashfs_statfs\n");
 569
 570         buf->f_type = SQUASHFS_MAGIC;
 571         buf->f_bsize = msblk->block_size;
 572         buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
 573         buf->f_bfree = buf->f_bavail = 0;
 574         buf->f_files = msblk->inodes;
 575         buf->f_ffree = 0;
 576         buf->f_namelen = SQUASHFS_NAME_LEN;
 577         buf->f_fsid = u64_to_fsid(id);
 578
 579         return 0;
 580 }
 581
 582
 583 static void squashfs_put_super(struct super_block *sb)
 584 {
 585         if (sb->s_fs_info) {
 586                 struct squashfs_sb_info *sbi = sb->s_fs_info;
 587                 squashfs_cache_delete(sbi->block_cache);
 588                 squashfs_cache_delete(sbi->fragment_cache);
 589                 squashfs_cache_delete(sbi->read_page);
 590                 if (sbi->cache_mapping)
 591                         iput(sbi->cache_mapping->host);
 592                 sbi->thread_ops->destroy(sbi);
 593                 kfree(sbi->id_table);
 594                 kfree(sbi->fragment_index);
 595                 kfree(sbi->meta_index);
 596                 kfree(sbi->inode_lookup_table);
 597                 kfree(sbi->xattr_id_table);
 598                 kfree(sb->s_fs_info);
 599                 sb->s_fs_info = NULL;
 600         }
 601 }
 602
 603 static struct kmem_cache *squashfs_inode_cachep;
 604
 605
 606 static void init_once(void *foo)
 607 {
 608         struct squashfs_inode_info *ei = foo;
 609
 610         inode_init_once(&ei->vfs_inode);
 611 }
 612
 613
 614 static int __init init_inodecache(void)
 615 {
 616         squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
 617                 sizeof(struct squashfs_inode_info), 0,
 618                 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
 619                 init_once);
 620
 621         return squashfs_inode_cachep ? 0 : -ENOMEM;
 622 }
 623
 624
 625 static void destroy_inodecache(void)
 626 {
 627         /*
 628          * Make sure all delayed rcu free inodes are flushed before we
 629          * destroy cache.
 630          */
 631         rcu_barrier();
 632         kmem_cache_destroy(squashfs_inode_cachep);
 633 }
 634
 635
 636 static int __init init_squashfs_fs(void)
 637 {
 638         int err = init_inodecache();
 639
 640         if (err)
 641                 return err;
 642
 643         err = register_filesystem(&squashfs_fs_type);
 644         if (err) {
 645                 destroy_inodecache();
 646                 return err;
 647         }
 648
 649         pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
 650
 651         return 0;
 652 }
 653
 654
 655 static void __exit exit_squashfs_fs(void)
 656 {
 657         unregister_filesystem(&squashfs_fs_type);
 658         destroy_inodecache();
 659 }
 660
 661
 662 static struct inode *squashfs_alloc_inode(struct super_block *sb)
 663 {
 664         struct squashfs_inode_info *ei =
 665                 alloc_inode_sb(sb, squashfs_inode_cachep, GFP_KERNEL);
 666
 667         return ei ? &ei->vfs_inode : NULL;
 668 }
 669
 670
 671 static void squashfs_free_inode(struct inode *inode)
 672 {
 673         kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
 674 }
 675
 676 static struct file_system_type squashfs_fs_type = {
 677         .owner = THIS_MODULE,
 678         .name = "squashfs",
 679         .init_fs_context = squashfs_init_fs_context,
 680         .parameters = squashfs_fs_parameters,
 681         .kill_sb = kill_block_super,
 682         .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
 683 };
 684 MODULE_ALIAS_FS("squashfs");
 685
 686 static const struct super_operations squashfs_super_ops = {
 687         .alloc_inode = squashfs_alloc_inode,
 688         .free_inode = squashfs_free_inode,
 689         .statfs = squashfs_statfs,
 690         .put_super = squashfs_put_super,
 691         .show_options = squashfs_show_options,
 692 };
 693
 694 module_init(init_squashfs_fs);
 695 module_exit(exit_squashfs_fs);
 696 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
 697 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
 698 MODULE_LICENSE("GPL");