fs/btrfs/super.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/module.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/fs.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/highmem.h>
  25 #include <linux/time.h>
  26 #include <linux/init.h>
  27 #include <linux/string.h>
  28 #include <linux/smp_lock.h>
  29 #include <linux/backing-dev.h>
  30 #include <linux/mount.h>
  31 #include <linux/mpage.h>
  32 #include <linux/swap.h>
  33 #include <linux/writeback.h>
  34 #include <linux/statfs.h>
  35 #include <linux/compat.h>
  36 #include <linux/parser.h>
  37 #include <linux/ctype.h>
  38 #include <linux/namei.h>
  39 #include <linux/miscdevice.h>
  40 #include <linux/version.h>
  41 #include "compat.h"
  42 #include "ctree.h"
  43 #include "disk-io.h"
  44 #include "transaction.h"
  45 #include "btrfs_inode.h"
  46 #include "ioctl.h"
  47 #include "print-tree.h"
  48 #include "xattr.h"
  49 #include "volumes.h"
  50 #include "version.h"
  51 #include "export.h"
  52 #include "compression.h"
  53
  54 #define BTRFS_SUPER_MAGIC 0x9123683E
  55
  56 static struct super_operations btrfs_super_ops;
  57
  58 static void btrfs_put_super (struct super_block * sb)
  59 {
  60         struct btrfs_root *root = btrfs_sb(sb);
  61         struct btrfs_fs_info *fs = root->fs_info;
  62         int ret;
  63
  64         ret = close_ctree(root);
  65         if (ret) {
  66                 printk("close ctree returns %d\n", ret);
  67         }
  68         btrfs_sysfs_del_super(fs);
  69         sb->s_fs_info = NULL;
  70 }
  71
  72 enum {
  73         Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
  74         Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
  75         Opt_ssd, Opt_thread_pool, Opt_noacl,  Opt_compress, Opt_err,
  76 };
  77
  78 static match_table_t tokens = {
  79         {Opt_degraded, "degraded"},
  80         {Opt_subvol, "subvol=%s"},
  81         {Opt_device, "device=%s"},
  82         {Opt_nodatasum, "nodatasum"},
  83         {Opt_nodatacow, "nodatacow"},
  84         {Opt_nobarrier, "nobarrier"},
  85         {Opt_max_extent, "max_extent=%s"},
  86         {Opt_max_inline, "max_inline=%s"},
  87         {Opt_alloc_start, "alloc_start=%s"},
  88         {Opt_thread_pool, "thread_pool=%d"},
  89         {Opt_compress, "compress"},
  90         {Opt_ssd, "ssd"},
  91         {Opt_noacl, "noacl"},
  92         {Opt_err, NULL},
  93 };
  94
  95 u64 btrfs_parse_size(char *str)
  96 {
  97         u64 res;
  98         int mult = 1;
  99         char *end;
 100         char last;
 101
 102         res = simple_strtoul(str, &end, 10);
 103
 104         last = end[0];
 105         if (isalpha(last)) {
 106                 last = tolower(last);
 107                 switch (last) {
 108                 case 'g':
 109                         mult *= 1024;
 110                 case 'm':
 111                         mult *= 1024;
 112                 case 'k':
 113                         mult *= 1024;
 114                 }
 115                 res = res * mult;
 116         }
 117         return res;
 118 }
 119
 120 /*
 121  * Regular mount options parser.  Everything that is needed only when
 122  * reading in a new superblock is parsed here.
 123  */
 124 int btrfs_parse_options(struct btrfs_root *root, char *options)
 125 {
 126         struct btrfs_fs_info *info = root->fs_info;
 127         substring_t args[MAX_OPT_ARGS];
 128         char *p, *num;
 129         int intarg;
 130
 131         if (!options)
 132                 return 0;
 133
 134         /*
 135          * strsep changes the string, duplicate it because parse_options
 136          * gets called twice
 137          */
 138         options = kstrdup(options, GFP_NOFS);
 139         if (!options)
 140                 return -ENOMEM;
 141
 142
 143         while ((p = strsep(&options, ",")) != NULL) {
 144                 int token;
 145                 if (!*p)
 146                         continue;
 147
 148                 token = match_token(p, tokens, args);
 149                 switch (token) {
 150                 case Opt_degraded:
 151                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 152                         btrfs_set_opt(info->mount_opt, DEGRADED);
 153                         break;
 154                 case Opt_subvol:
 155                 case Opt_device:
 156                         /*
 157                          * These are parsed by btrfs_parse_early_options
 158                          * and can be happily ignored here.
 159                          */
 160                         break;
 161                 case Opt_nodatasum:
 162                         printk(KERN_INFO "btrfs: setting nodatacsum\n");
 163                         btrfs_set_opt(info->mount_opt, NODATASUM);
 164                         break;
 165                 case Opt_nodatacow:
 166                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 167                         btrfs_set_opt(info->mount_opt, NODATACOW);
 168                         btrfs_set_opt(info->mount_opt, NODATASUM);
 169                         break;
 170                 case Opt_compress:
 171                         printk(KERN_INFO "btrfs: use compression\n");
 172                         btrfs_set_opt(info->mount_opt, COMPRESS);
 173                         break;
 174                 case Opt_ssd:
 175                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 176                         btrfs_set_opt(info->mount_opt, SSD);
 177                         break;
 178                 case Opt_nobarrier:
 179                         printk(KERN_INFO "btrfs: turning off barriers\n");
 180                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 181                         break;
 182                 case Opt_thread_pool:
 183                         intarg = 0;
 184                         match_int(&args[0], &intarg);
 185                         if (intarg) {
 186                                 info->thread_pool_size = intarg;
 187                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 188                                        info->thread_pool_size);
 189                         }
 190                         break;
 191                 case Opt_max_extent:
 192                         num = match_strdup(&args[0]);
 193                         if (num) {
 194                                 info->max_extent = btrfs_parse_size(num);
 195                                 kfree(num);
 196
 197                                 info->max_extent = max_t(u64,
 198                                         info->max_extent, root->sectorsize);
 199                                 printk(KERN_INFO "btrfs: max_extent at %llu\n",
 200                                        info->max_extent);
 201                         }
 202                         break;
 203                 case Opt_max_inline:
 204                         num = match_strdup(&args[0]);
 205                         if (num) {
 206                                 info->max_inline = btrfs_parse_size(num);
 207                                 kfree(num);
 208
 209                                 if (info->max_inline) {
 210                                         info->max_inline = max_t(u64,
 211                                                 info->max_inline,
 212                                                 root->sectorsize);
 213                                 }
 214                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 215                                         info->max_inline);
 216                         }
 217                         break;
 218                 case Opt_alloc_start:
 219                         num = match_strdup(&args[0]);
 220                         if (num) {
 221                                 info->alloc_start = btrfs_parse_size(num);
 222                                 kfree(num);
 223                                 printk(KERN_INFO
 224                                         "btrfs: allocations start at %llu\n",
 225                                         info->alloc_start);
 226                         }
 227                         break;
 228                 case Opt_noacl:
 229                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 230                         break;
 231                 default:
 232                         break;
 233                 }
 234         }
 235         kfree(options);
 236         return 0;
 237 }
 238
 239 /*
 240  * Parse mount options that are required early in the mount process.
 241  *
 242  * All other options will be parsed on much later in the mount process and
 243  * only when we need to allocate a new super block.
 244  */
 245 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 246                 void *holder, char **subvol_name,
 247                 struct btrfs_fs_devices **fs_devices)
 248 {
 249         substring_t args[MAX_OPT_ARGS];
 250         char *opts, *p;
 251         int error = 0;
 252
 253         if (!options)
 254                 goto out;
 255
 256         /*
 257          * strsep changes the string, duplicate it because parse_options
 258          * gets called twice
 259          */
 260         opts = kstrdup(options, GFP_KERNEL);
 261         if (!opts)
 262                 return -ENOMEM;
 263
 264         while ((p = strsep(&opts, ",")) != NULL) {
 265                 int token;
 266                 if (!*p)
 267                         continue;
 268
 269                 token = match_token(p, tokens, args);
 270                 switch (token) {
 271                 case Opt_subvol:
 272                         *subvol_name = match_strdup(&args[0]);
 273                         break;
 274                 case Opt_device:
 275                         error = btrfs_scan_one_device(match_strdup(&args[0]),
 276                                         flags, holder, fs_devices);
 277                         if (error)
 278                                 goto out_free_opts;
 279                         break;
 280                 default:
 281                         break;
 282                 }
 283         }
 284
 285  out_free_opts:
 286         kfree(opts);
 287  out:
 288         /*
 289          * If no subvolume name is specified we use the default one.  Allocate
 290          * a copy of the string "." here so that code later in the
 291          * mount path doesn't care if it's the default volume or another one.
 292          */
 293         if (!*subvol_name) {
 294                 *subvol_name = kstrdup(".", GFP_KERNEL);
 295                 if (!*subvol_name)
 296                         return -ENOMEM;
 297         }
 298         return error;
 299 }
 300
 301 static int btrfs_fill_super(struct super_block * sb,
 302                             struct btrfs_fs_devices *fs_devices,
 303                             void * data, int silent)
 304 {
 305         struct inode * inode;
 306         struct dentry * root_dentry;
 307         struct btrfs_super_block *disk_super;
 308         struct btrfs_root *tree_root;
 309         struct btrfs_inode *bi;
 310         int err;
 311
 312         sb->s_maxbytes = MAX_LFS_FILESIZE;
 313         sb->s_magic = BTRFS_SUPER_MAGIC;
 314         sb->s_op = &btrfs_super_ops;
 315         sb->s_export_op = &btrfs_export_ops;
 316         sb->s_xattr = btrfs_xattr_handlers;
 317         sb->s_time_gran = 1;
 318         sb->s_flags |= MS_POSIXACL;
 319
 320         tree_root = open_ctree(sb, fs_devices, (char *)data);
 321
 322         if (IS_ERR(tree_root)) {
 323                 printk("btrfs: open_ctree failed\n");
 324                 return PTR_ERR(tree_root);
 325         }
 326         sb->s_fs_info = tree_root;
 327         disk_super = &tree_root->fs_info->super_copy;
 328         inode = btrfs_iget_locked(sb, BTRFS_FIRST_FREE_OBJECTID,
 329                                   tree_root->fs_info->fs_root);
 330         bi = BTRFS_I(inode);
 331         bi->location.objectid = inode->i_ino;
 332         bi->location.offset = 0;
 333         bi->root = tree_root->fs_info->fs_root;
 334
 335         btrfs_set_key_type(&bi->location, BTRFS_INODE_ITEM_KEY);
 336
 337         if (!inode) {
 338                 err = -ENOMEM;
 339                 goto fail_close;
 340         }
 341         if (inode->i_state & I_NEW) {
 342                 btrfs_read_locked_inode(inode);
 343                 unlock_new_inode(inode);
 344         }
 345
 346         root_dentry = d_alloc_root(inode);
 347         if (!root_dentry) {
 348                 iput(inode);
 349                 err = -ENOMEM;
 350                 goto fail_close;
 351         }
 352
 353         /* this does the super kobj at the same time */
 354         err = btrfs_sysfs_add_super(tree_root->fs_info);
 355         if (err)
 356                 goto fail_close;
 357
 358         sb->s_root = root_dentry;
 359
 360         save_mount_options(sb, data);
 361         return 0;
 362
 363 fail_close:
 364         close_ctree(tree_root);
 365         return err;
 366 }
 367
 368 int btrfs_sync_fs(struct super_block *sb, int wait)
 369 {
 370         struct btrfs_trans_handle *trans;
 371         struct btrfs_root *root;
 372         int ret;
 373         root = btrfs_sb(sb);
 374
 375         if (sb->s_flags & MS_RDONLY)
 376                 return 0;
 377
 378         sb->s_dirt = 0;
 379         if (!wait) {
 380                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 381                 return 0;
 382         }
 383
 384         btrfs_start_delalloc_inodes(root);
 385         btrfs_wait_ordered_extents(root, 0);
 386
 387         btrfs_clean_old_snapshots(root);
 388         trans = btrfs_start_transaction(root, 1);
 389         ret = btrfs_commit_transaction(trans, root);
 390         sb->s_dirt = 0;
 391         return ret;
 392 }
 393
 394 static void btrfs_write_super(struct super_block *sb)
 395 {
 396         sb->s_dirt = 0;
 397 }
 398
 399 static int btrfs_test_super(struct super_block *s, void *data)
 400 {
 401         struct btrfs_fs_devices *test_fs_devices = data;
 402         struct btrfs_root *root = btrfs_sb(s);
 403
 404         return root->fs_info->fs_devices == test_fs_devices;
 405 }
 406
 407 /*
 408  * Find a superblock for the given device / mount point.
 409  *
 410  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 411  *        for multiple device setup.  Make sure to keep it in sync.
 412  */
 413 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 414                 const char *dev_name, void *data, struct vfsmount *mnt)
 415 {
 416         char *subvol_name = NULL;
 417         struct block_device *bdev = NULL;
 418         struct super_block *s;
 419         struct dentry *root;
 420         struct btrfs_fs_devices *fs_devices = NULL;
 421         fmode_t mode = FMODE_READ;
 422         int error = 0;
 423
 424         if (!(flags & MS_RDONLY))
 425                 mode |= FMODE_WRITE;
 426
 427         error = btrfs_parse_early_options(data, mode, fs_type,
 428                                           &subvol_name, &fs_devices);
 429         if (error)
 430                 goto error;
 431
 432         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
 433         if (error)
 434                 goto error_free_subvol_name;
 435
 436         error = btrfs_open_devices(fs_devices, mode, fs_type);
 437         if (error)
 438                 goto error_free_subvol_name;
 439
 440         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 441                 error = -EACCES;
 442                 goto error_close_devices;
 443         }
 444
 445         bdev = fs_devices->latest_bdev;
 446         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
 447         if (IS_ERR(s))
 448                 goto error_s;
 449
 450         if (s->s_root) {
 451                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 452                         up_write(&s->s_umount);
 453                         deactivate_super(s);
 454                         error = -EBUSY;
 455                         goto error_close_devices;
 456                 }
 457
 458                 btrfs_close_devices(fs_devices);
 459         } else {
 460                 char b[BDEVNAME_SIZE];
 461
 462                 s->s_flags = flags;
 463                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 464                 error = btrfs_fill_super(s, fs_devices, data,
 465                                          flags & MS_SILENT ? 1 : 0);
 466                 if (error) {
 467                         up_write(&s->s_umount);
 468                         deactivate_super(s);
 469                         goto error;
 470                 }
 471
 472                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 473                 s->s_flags |= MS_ACTIVE;
 474         }
 475
 476         if (!strcmp(subvol_name, "."))
 477                 root = dget(s->s_root);
 478         else {
 479                 mutex_lock(&s->s_root->d_inode->i_mutex);
 480                 root = lookup_one_len(subvol_name, s->s_root, strlen(subvol_name));
 481                 mutex_unlock(&s->s_root->d_inode->i_mutex);
 482                 if (IS_ERR(root)) {
 483                         up_write(&s->s_umount);
 484                         deactivate_super(s);
 485                         error = PTR_ERR(root);
 486                         goto error;
 487                 }
 488                 if (!root->d_inode) {
 489                         dput(root);
 490                         up_write(&s->s_umount);
 491                         deactivate_super(s);
 492                         error = -ENXIO;
 493                         goto error;
 494                 }
 495         }
 496
 497         mnt->mnt_sb = s;
 498         mnt->mnt_root = root;
 499
 500         kfree(subvol_name);
 501         return 0;
 502
 503 error_s:
 504         error = PTR_ERR(s);
 505 error_close_devices:
 506         btrfs_close_devices(fs_devices);
 507 error_free_subvol_name:
 508         kfree(subvol_name);
 509 error:
 510         return error;
 511 }
 512
 513 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 514 {
 515         struct btrfs_root *root = btrfs_sb(sb);
 516         int ret;
 517
 518         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 519                 return 0;
 520
 521         if (*flags & MS_RDONLY) {
 522                 sb->s_flags |= MS_RDONLY;
 523
 524                 ret =  btrfs_commit_super(root);
 525                 WARN_ON(ret);
 526         } else {
 527                 if (root->fs_info->fs_devices->rw_devices == 0)
 528                         return -EACCES;
 529
 530                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 531                         return -EINVAL;
 532
 533                 ret = btrfs_cleanup_reloc_trees(root);
 534                 WARN_ON(ret);
 535
 536                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 537                 WARN_ON(ret);
 538
 539                 sb->s_flags &= ~MS_RDONLY;
 540         }
 541
 542         return 0;
 543 }
 544
 545 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 546 {
 547         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 548         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 549         int bits = dentry->d_sb->s_blocksize_bits;
 550         __be32 *fsid = (__be32 *)root->fs_info->fsid;
 551
 552         buf->f_namelen = BTRFS_NAME_LEN;
 553         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 554         buf->f_bfree = buf->f_blocks -
 555                 (btrfs_super_bytes_used(disk_super) >> bits);
 556         buf->f_bavail = buf->f_bfree;
 557         buf->f_bsize = dentry->d_sb->s_blocksize;
 558         buf->f_type = BTRFS_SUPER_MAGIC;
 559         /* We treat it as constant endianness (it doesn't matter _which_)
 560            because we want the fsid to come out the same whether mounted
 561            on a big-endian or little-endian host */
 562         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
 563         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
 564         /* Mask in the root object ID too, to disambiguate subvols */
 565         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
 566         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
 567
 568         return 0;
 569 }
 570
 571 static struct file_system_type btrfs_fs_type = {
 572         .owner          = THIS_MODULE,
 573         .name           = "btrfs",
 574         .get_sb         = btrfs_get_sb,
 575         .kill_sb        = kill_anon_super,
 576         .fs_flags       = FS_REQUIRES_DEV,
 577 };
 578
 579 /*
 580  * used by btrfsctl to scan devices when no FS is mounted
 581  */
 582 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 583                                 unsigned long arg)
 584 {
 585         struct btrfs_ioctl_vol_args *vol;
 586         struct btrfs_fs_devices *fs_devices;
 587         int ret = 0;
 588         int len;
 589
 590         vol = kmalloc(sizeof(*vol), GFP_KERNEL);
 591         if (copy_from_user(vol, (void __user *)arg, sizeof(*vol))) {
 592                 ret = -EFAULT;
 593                 goto out;
 594         }
 595         len = strnlen(vol->name, BTRFS_PATH_NAME_MAX);
 596         switch (cmd) {
 597         case BTRFS_IOC_SCAN_DEV:
 598                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
 599                                             &btrfs_fs_type, &fs_devices);
 600                 break;
 601         }
 602 out:
 603         kfree(vol);
 604         return ret;
 605 }
 606
 607 static void btrfs_write_super_lockfs(struct super_block *sb)
 608 {
 609         struct btrfs_root *root = btrfs_sb(sb);
 610         mutex_lock(&root->fs_info->transaction_kthread_mutex);
 611         mutex_lock(&root->fs_info->cleaner_mutex);
 612 }
 613
 614 static void btrfs_unlockfs(struct super_block *sb)
 615 {
 616         struct btrfs_root *root = btrfs_sb(sb);
 617         mutex_unlock(&root->fs_info->cleaner_mutex);
 618         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 619 }
 620
 621 static struct super_operations btrfs_super_ops = {
 622         .delete_inode   = btrfs_delete_inode,
 623         .put_super      = btrfs_put_super,
 624         .write_super    = btrfs_write_super,
 625         .sync_fs        = btrfs_sync_fs,
 626         .show_options   = generic_show_options,
 627         .write_inode    = btrfs_write_inode,
 628         .dirty_inode    = btrfs_dirty_inode,
 629         .alloc_inode    = btrfs_alloc_inode,
 630         .destroy_inode  = btrfs_destroy_inode,
 631         .statfs         = btrfs_statfs,
 632         .remount_fs     = btrfs_remount,
 633         .write_super_lockfs = btrfs_write_super_lockfs,
 634         .unlockfs       = btrfs_unlockfs,
 635 };
 636
 637 static const struct file_operations btrfs_ctl_fops = {
 638         .unlocked_ioctl  = btrfs_control_ioctl,
 639         .compat_ioctl = btrfs_control_ioctl,
 640         .owner   = THIS_MODULE,
 641 };
 642
 643 static struct miscdevice btrfs_misc = {
 644         .minor          = MISC_DYNAMIC_MINOR,
 645         .name           = "btrfs-control",
 646         .fops           = &btrfs_ctl_fops
 647 };
 648
 649 static int btrfs_interface_init(void)
 650 {
 651         return misc_register(&btrfs_misc);
 652 }
 653
 654 static void btrfs_interface_exit(void)
 655 {
 656         if (misc_deregister(&btrfs_misc) < 0)
 657                 printk("misc_deregister failed for control device");
 658 }
 659
 660 static int __init init_btrfs_fs(void)
 661 {
 662         int err;
 663
 664         err = btrfs_init_sysfs();
 665         if (err)
 666                 return err;
 667
 668         err = btrfs_init_cachep();
 669         if (err)
 670                 goto free_sysfs;
 671
 672         err = extent_io_init();
 673         if (err)
 674                 goto free_cachep;
 675
 676         err = extent_map_init();
 677         if (err)
 678                 goto free_extent_io;
 679
 680         err = btrfs_interface_init();
 681         if (err)
 682                 goto free_extent_map;
 683
 684         err = register_filesystem(&btrfs_fs_type);
 685         if (err)
 686                 goto unregister_ioctl;
 687
 688         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 689         return 0;
 690
 691 unregister_ioctl:
 692         btrfs_interface_exit();
 693 free_extent_map:
 694         extent_map_exit();
 695 free_extent_io:
 696         extent_io_exit();
 697 free_cachep:
 698         btrfs_destroy_cachep();
 699 free_sysfs:
 700         btrfs_exit_sysfs();
 701         return err;
 702 }
 703
 704 static void __exit exit_btrfs_fs(void)
 705 {
 706         btrfs_destroy_cachep();
 707         extent_map_exit();
 708         extent_io_exit();
 709         btrfs_interface_exit();
 710         unregister_filesystem(&btrfs_fs_type);
 711         btrfs_exit_sysfs();
 712         btrfs_cleanup_fs_uuids();
 713         btrfs_zlib_exit();
 714 }
 715
 716 module_init(init_btrfs_fs)
 717 module_exit(exit_btrfs_fs)
 718
 719 MODULE_LICENSE("GPL");