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/magic.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
  55 static struct super_operations btrfs_super_ops;
  56
  57 static void btrfs_put_super(struct super_block *sb)
  58 {
  59         struct btrfs_root *root = btrfs_sb(sb);
  60         int ret;
  61
  62         ret = close_ctree(root);
  63         sb->s_fs_info = NULL;
  64 }
  65
  66 enum {
  67         Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
  68         Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
  69         Opt_ssd, Opt_thread_pool, Opt_noacl,  Opt_compress, Opt_err,
  70 };
  71
  72 static match_table_t tokens = {
  73         {Opt_degraded, "degraded"},
  74         {Opt_subvol, "subvol=%s"},
  75         {Opt_device, "device=%s"},
  76         {Opt_nodatasum, "nodatasum"},
  77         {Opt_nodatacow, "nodatacow"},
  78         {Opt_nobarrier, "nobarrier"},
  79         {Opt_max_extent, "max_extent=%s"},
  80         {Opt_max_inline, "max_inline=%s"},
  81         {Opt_alloc_start, "alloc_start=%s"},
  82         {Opt_thread_pool, "thread_pool=%d"},
  83         {Opt_compress, "compress"},
  84         {Opt_ssd, "ssd"},
  85         {Opt_noacl, "noacl"},
  86         {Opt_err, NULL},
  87 };
  88
  89 u64 btrfs_parse_size(char *str)
  90 {
  91         u64 res;
  92         int mult = 1;
  93         char *end;
  94         char last;
  95
  96         res = simple_strtoul(str, &end, 10);
  97
  98         last = end[0];
  99         if (isalpha(last)) {
 100                 last = tolower(last);
 101                 switch (last) {
 102                 case 'g':
 103                         mult *= 1024;
 104                 case 'm':
 105                         mult *= 1024;
 106                 case 'k':
 107                         mult *= 1024;
 108                 }
 109                 res = res * mult;
 110         }
 111         return res;
 112 }
 113
 114 /*
 115  * Regular mount options parser.  Everything that is needed only when
 116  * reading in a new superblock is parsed here.
 117  */
 118 int btrfs_parse_options(struct btrfs_root *root, char *options)
 119 {
 120         struct btrfs_fs_info *info = root->fs_info;
 121         substring_t args[MAX_OPT_ARGS];
 122         char *p, *num;
 123         int intarg;
 124
 125         if (!options)
 126                 return 0;
 127
 128         /*
 129          * strsep changes the string, duplicate it because parse_options
 130          * gets called twice
 131          */
 132         options = kstrdup(options, GFP_NOFS);
 133         if (!options)
 134                 return -ENOMEM;
 135
 136
 137         while ((p = strsep(&options, ",")) != NULL) {
 138                 int token;
 139                 if (!*p)
 140                         continue;
 141
 142                 token = match_token(p, tokens, args);
 143                 switch (token) {
 144                 case Opt_degraded:
 145                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 146                         btrfs_set_opt(info->mount_opt, DEGRADED);
 147                         break;
 148                 case Opt_subvol:
 149                 case Opt_device:
 150                         /*
 151                          * These are parsed by btrfs_parse_early_options
 152                          * and can be happily ignored here.
 153                          */
 154                         break;
 155                 case Opt_nodatasum:
 156                         printk(KERN_INFO "btrfs: setting nodatacsum\n");
 157                         btrfs_set_opt(info->mount_opt, NODATASUM);
 158                         break;
 159                 case Opt_nodatacow:
 160                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 161                         btrfs_set_opt(info->mount_opt, NODATACOW);
 162                         btrfs_set_opt(info->mount_opt, NODATASUM);
 163                         break;
 164                 case Opt_compress:
 165                         printk(KERN_INFO "btrfs: use compression\n");
 166                         btrfs_set_opt(info->mount_opt, COMPRESS);
 167                         break;
 168                 case Opt_ssd:
 169                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 170                         btrfs_set_opt(info->mount_opt, SSD);
 171                         break;
 172                 case Opt_nobarrier:
 173                         printk(KERN_INFO "btrfs: turning off barriers\n");
 174                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 175                         break;
 176                 case Opt_thread_pool:
 177                         intarg = 0;
 178                         match_int(&args[0], &intarg);
 179                         if (intarg) {
 180                                 info->thread_pool_size = intarg;
 181                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 182                                        info->thread_pool_size);
 183                         }
 184                         break;
 185                 case Opt_max_extent:
 186                         num = match_strdup(&args[0]);
 187                         if (num) {
 188                                 info->max_extent = btrfs_parse_size(num);
 189                                 kfree(num);
 190
 191                                 info->max_extent = max_t(u64,
 192                                         info->max_extent, root->sectorsize);
 193                                 printk(KERN_INFO "btrfs: max_extent at %llu\n",
 194                                        info->max_extent);
 195                         }
 196                         break;
 197                 case Opt_max_inline:
 198                         num = match_strdup(&args[0]);
 199                         if (num) {
 200                                 info->max_inline = btrfs_parse_size(num);
 201                                 kfree(num);
 202
 203                                 if (info->max_inline) {
 204                                         info->max_inline = max_t(u64,
 205                                                 info->max_inline,
 206                                                 root->sectorsize);
 207                                 }
 208                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 209                                         info->max_inline);
 210                         }
 211                         break;
 212                 case Opt_alloc_start:
 213                         num = match_strdup(&args[0]);
 214                         if (num) {
 215                                 info->alloc_start = btrfs_parse_size(num);
 216                                 kfree(num);
 217                                 printk(KERN_INFO
 218                                         "btrfs: allocations start at %llu\n",
 219                                         info->alloc_start);
 220                         }
 221                         break;
 222                 case Opt_noacl:
 223                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 224                         break;
 225                 default:
 226                         break;
 227                 }
 228         }
 229         kfree(options);
 230         return 0;
 231 }
 232
 233 /*
 234  * Parse mount options that are required early in the mount process.
 235  *
 236  * All other options will be parsed on much later in the mount process and
 237  * only when we need to allocate a new super block.
 238  */
 239 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 240                 void *holder, char **subvol_name,
 241                 struct btrfs_fs_devices **fs_devices)
 242 {
 243         substring_t args[MAX_OPT_ARGS];
 244         char *opts, *p;
 245         int error = 0;
 246
 247         if (!options)
 248                 goto out;
 249
 250         /*
 251          * strsep changes the string, duplicate it because parse_options
 252          * gets called twice
 253          */
 254         opts = kstrdup(options, GFP_KERNEL);
 255         if (!opts)
 256                 return -ENOMEM;
 257
 258         while ((p = strsep(&opts, ",")) != NULL) {
 259                 int token;
 260                 if (!*p)
 261                         continue;
 262
 263                 token = match_token(p, tokens, args);
 264                 switch (token) {
 265                 case Opt_subvol:
 266                         *subvol_name = match_strdup(&args[0]);
 267                         break;
 268                 case Opt_device:
 269                         error = btrfs_scan_one_device(match_strdup(&args[0]),
 270                                         flags, holder, fs_devices);
 271                         if (error)
 272                                 goto out_free_opts;
 273                         break;
 274                 default:
 275                         break;
 276                 }
 277         }
 278
 279  out_free_opts:
 280         kfree(opts);
 281  out:
 282         /*
 283          * If no subvolume name is specified we use the default one.  Allocate
 284          * a copy of the string "." here so that code later in the
 285          * mount path doesn't care if it's the default volume or another one.
 286          */
 287         if (!*subvol_name) {
 288                 *subvol_name = kstrdup(".", GFP_KERNEL);
 289                 if (!*subvol_name)
 290                         return -ENOMEM;
 291         }
 292         return error;
 293 }
 294
 295 static int btrfs_fill_super(struct super_block *sb,
 296                             struct btrfs_fs_devices *fs_devices,
 297                             void *data, int silent)
 298 {
 299         struct inode *inode;
 300         struct dentry *root_dentry;
 301         struct btrfs_super_block *disk_super;
 302         struct btrfs_root *tree_root;
 303         struct btrfs_inode *bi;
 304         int err;
 305
 306         sb->s_maxbytes = MAX_LFS_FILESIZE;
 307         sb->s_magic = BTRFS_SUPER_MAGIC;
 308         sb->s_op = &btrfs_super_ops;
 309         sb->s_export_op = &btrfs_export_ops;
 310         sb->s_xattr = btrfs_xattr_handlers;
 311         sb->s_time_gran = 1;
 312         sb->s_flags |= MS_POSIXACL;
 313
 314         tree_root = open_ctree(sb, fs_devices, (char *)data);
 315
 316         if (IS_ERR(tree_root)) {
 317                 printk("btrfs: open_ctree failed\n");
 318                 return PTR_ERR(tree_root);
 319         }
 320         sb->s_fs_info = tree_root;
 321         disk_super = &tree_root->fs_info->super_copy;
 322         inode = btrfs_iget_locked(sb, BTRFS_FIRST_FREE_OBJECTID,
 323                                   tree_root->fs_info->fs_root);
 324         bi = BTRFS_I(inode);
 325         bi->location.objectid = inode->i_ino;
 326         bi->location.offset = 0;
 327         bi->root = tree_root->fs_info->fs_root;
 328
 329         btrfs_set_key_type(&bi->location, BTRFS_INODE_ITEM_KEY);
 330
 331         if (!inode) {
 332                 err = -ENOMEM;
 333                 goto fail_close;
 334         }
 335         if (inode->i_state & I_NEW) {
 336                 btrfs_read_locked_inode(inode);
 337                 unlock_new_inode(inode);
 338         }
 339
 340         root_dentry = d_alloc_root(inode);
 341         if (!root_dentry) {
 342                 iput(inode);
 343                 err = -ENOMEM;
 344                 goto fail_close;
 345         }
 346 #if 0
 347         /* this does the super kobj at the same time */
 348         err = btrfs_sysfs_add_super(tree_root->fs_info);
 349         if (err)
 350                 goto fail_close;
 351 #endif
 352
 353         sb->s_root = root_dentry;
 354
 355         save_mount_options(sb, data);
 356         return 0;
 357
 358 fail_close:
 359         close_ctree(tree_root);
 360         return err;
 361 }
 362
 363 int btrfs_sync_fs(struct super_block *sb, int wait)
 364 {
 365         struct btrfs_trans_handle *trans;
 366         struct btrfs_root *root;
 367         int ret;
 368         root = btrfs_sb(sb);
 369
 370         if (sb->s_flags & MS_RDONLY)
 371                 return 0;
 372
 373         sb->s_dirt = 0;
 374         if (!wait) {
 375                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 376                 return 0;
 377         }
 378
 379         btrfs_start_delalloc_inodes(root);
 380         btrfs_wait_ordered_extents(root, 0);
 381
 382         trans = btrfs_start_transaction(root, 1);
 383         ret = btrfs_commit_transaction(trans, root);
 384         sb->s_dirt = 0;
 385         return ret;
 386 }
 387
 388 static void btrfs_write_super(struct super_block *sb)
 389 {
 390         sb->s_dirt = 0;
 391 }
 392
 393 static int btrfs_test_super(struct super_block *s, void *data)
 394 {
 395         struct btrfs_fs_devices *test_fs_devices = data;
 396         struct btrfs_root *root = btrfs_sb(s);
 397
 398         return root->fs_info->fs_devices == test_fs_devices;
 399 }
 400
 401 /*
 402  * Find a superblock for the given device / mount point.
 403  *
 404  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 405  *        for multiple device setup.  Make sure to keep it in sync.
 406  */
 407 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 408                 const char *dev_name, void *data, struct vfsmount *mnt)
 409 {
 410         char *subvol_name = NULL;
 411         struct block_device *bdev = NULL;
 412         struct super_block *s;
 413         struct dentry *root;
 414         struct btrfs_fs_devices *fs_devices = NULL;
 415         fmode_t mode = FMODE_READ;
 416         int error = 0;
 417
 418         if (!(flags & MS_RDONLY))
 419                 mode |= FMODE_WRITE;
 420
 421         error = btrfs_parse_early_options(data, mode, fs_type,
 422                                           &subvol_name, &fs_devices);
 423         if (error)
 424                 return error;
 425
 426         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
 427         if (error)
 428                 goto error_free_subvol_name;
 429
 430         error = btrfs_open_devices(fs_devices, mode, fs_type);
 431         if (error)
 432                 goto error_free_subvol_name;
 433
 434         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 435                 error = -EACCES;
 436                 goto error_close_devices;
 437         }
 438
 439         bdev = fs_devices->latest_bdev;
 440         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
 441         if (IS_ERR(s))
 442                 goto error_s;
 443
 444         if (s->s_root) {
 445                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 446                         up_write(&s->s_umount);
 447                         deactivate_super(s);
 448                         error = -EBUSY;
 449                         goto error_close_devices;
 450                 }
 451
 452                 btrfs_close_devices(fs_devices);
 453         } else {
 454                 char b[BDEVNAME_SIZE];
 455
 456                 s->s_flags = flags;
 457                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 458                 error = btrfs_fill_super(s, fs_devices, data,
 459                                          flags & MS_SILENT ? 1 : 0);
 460                 if (error) {
 461                         up_write(&s->s_umount);
 462                         deactivate_super(s);
 463                         goto error_free_subvol_name;
 464                 }
 465
 466                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 467                 s->s_flags |= MS_ACTIVE;
 468         }
 469
 470         if (!strcmp(subvol_name, "."))
 471                 root = dget(s->s_root);
 472         else {
 473                 mutex_lock(&s->s_root->d_inode->i_mutex);
 474                 root = lookup_one_len(subvol_name, s->s_root,
 475                                       strlen(subvol_name));
 476                 mutex_unlock(&s->s_root->d_inode->i_mutex);
 477
 478                 if (IS_ERR(root)) {
 479                         up_write(&s->s_umount);
 480                         deactivate_super(s);
 481                         error = PTR_ERR(root);
 482                         goto error_free_subvol_name;
 483                 }
 484                 if (!root->d_inode) {
 485                         dput(root);
 486                         up_write(&s->s_umount);
 487                         deactivate_super(s);
 488                         error = -ENXIO;
 489                         goto error_free_subvol_name;
 490                 }
 491         }
 492
 493         mnt->mnt_sb = s;
 494         mnt->mnt_root = root;
 495
 496         kfree(subvol_name);
 497         return 0;
 498
 499 error_s:
 500         error = PTR_ERR(s);
 501 error_close_devices:
 502         btrfs_close_devices(fs_devices);
 503 error_free_subvol_name:
 504         kfree(subvol_name);
 505         return error;
 506 }
 507
 508 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 509 {
 510         struct btrfs_root *root = btrfs_sb(sb);
 511         int ret;
 512
 513         ret = btrfs_parse_options(root, data);
 514         if (ret)
 515                 return -EINVAL;
 516
 517         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 518                 return 0;
 519
 520         if (*flags & MS_RDONLY) {
 521                 sb->s_flags |= MS_RDONLY;
 522
 523                 ret =  btrfs_commit_super(root);
 524                 WARN_ON(ret);
 525         } else {
 526                 if (root->fs_info->fs_devices->rw_devices == 0)
 527                         return -EACCES;
 528
 529                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 530                         return -EINVAL;
 531
 532                 ret = btrfs_cleanup_reloc_trees(root);
 533                 WARN_ON(ret);
 534
 535                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 536                 WARN_ON(ret);
 537
 538                 sb->s_flags &= ~MS_RDONLY;
 539         }
 540
 541         return 0;
 542 }
 543
 544 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 545 {
 546         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 547         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 548         int bits = dentry->d_sb->s_blocksize_bits;
 549         __be32 *fsid = (__be32 *)root->fs_info->fsid;
 550
 551         buf->f_namelen = BTRFS_NAME_LEN;
 552         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 553         buf->f_bfree = buf->f_blocks -
 554                 (btrfs_super_bytes_used(disk_super) >> bits);
 555         buf->f_bavail = buf->f_bfree;
 556         buf->f_bsize = dentry->d_sb->s_blocksize;
 557         buf->f_type = BTRFS_SUPER_MAGIC;
 558
 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 = -ENOTTY;
 588
 589         if (!capable(CAP_SYS_ADMIN))
 590                 return -EPERM;
 591
 592         vol = kmalloc(sizeof(*vol), GFP_KERNEL);
 593         if (!vol)
 594                 return -ENOMEM;
 595
 596         if (copy_from_user(vol, (void __user *)arg, sizeof(*vol))) {
 597                 ret = -EFAULT;
 598                 goto out;
 599         }
 600
 601         switch (cmd) {
 602         case BTRFS_IOC_SCAN_DEV:
 603                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
 604                                             &btrfs_fs_type, &fs_devices);
 605                 break;
 606         }
 607 out:
 608         kfree(vol);
 609         return ret;
 610 }
 611
 612 static int btrfs_freeze(struct super_block *sb)
 613 {
 614         struct btrfs_root *root = btrfs_sb(sb);
 615         mutex_lock(&root->fs_info->transaction_kthread_mutex);
 616         mutex_lock(&root->fs_info->cleaner_mutex);
 617         return 0;
 618 }
 619
 620 static int btrfs_unfreeze(struct super_block *sb)
 621 {
 622         struct btrfs_root *root = btrfs_sb(sb);
 623         mutex_unlock(&root->fs_info->cleaner_mutex);
 624         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 625         return 0;
 626 }
 627
 628 static struct super_operations btrfs_super_ops = {
 629         .delete_inode   = btrfs_delete_inode,
 630         .put_super      = btrfs_put_super,
 631         .write_super    = btrfs_write_super,
 632         .sync_fs        = btrfs_sync_fs,
 633         .show_options   = generic_show_options,
 634         .write_inode    = btrfs_write_inode,
 635         .dirty_inode    = btrfs_dirty_inode,
 636         .alloc_inode    = btrfs_alloc_inode,
 637         .destroy_inode  = btrfs_destroy_inode,
 638         .statfs         = btrfs_statfs,
 639         .remount_fs     = btrfs_remount,
 640         .freeze_fs      = btrfs_freeze,
 641         .unfreeze_fs    = btrfs_unfreeze,
 642 };
 643
 644 static const struct file_operations btrfs_ctl_fops = {
 645         .unlocked_ioctl  = btrfs_control_ioctl,
 646         .compat_ioctl = btrfs_control_ioctl,
 647         .owner   = THIS_MODULE,
 648 };
 649
 650 static struct miscdevice btrfs_misc = {
 651         .minor          = MISC_DYNAMIC_MINOR,
 652         .name           = "btrfs-control",
 653         .fops           = &btrfs_ctl_fops
 654 };
 655
 656 static int btrfs_interface_init(void)
 657 {
 658         return misc_register(&btrfs_misc);
 659 }
 660
 661 static void btrfs_interface_exit(void)
 662 {
 663         if (misc_deregister(&btrfs_misc) < 0)
 664                 printk(KERN_INFO "misc_deregister failed for control device");
 665 }
 666
 667 static int __init init_btrfs_fs(void)
 668 {
 669         int err;
 670
 671         err = btrfs_init_sysfs();
 672         if (err)
 673                 return err;
 674
 675         err = btrfs_init_cachep();
 676         if (err)
 677                 goto free_sysfs;
 678
 679         err = extent_io_init();
 680         if (err)
 681                 goto free_cachep;
 682
 683         err = extent_map_init();
 684         if (err)
 685                 goto free_extent_io;
 686
 687         err = btrfs_interface_init();
 688         if (err)
 689                 goto free_extent_map;
 690
 691         err = register_filesystem(&btrfs_fs_type);
 692         if (err)
 693                 goto unregister_ioctl;
 694
 695         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 696         return 0;
 697
 698 unregister_ioctl:
 699         btrfs_interface_exit();
 700 free_extent_map:
 701         extent_map_exit();
 702 free_extent_io:
 703         extent_io_exit();
 704 free_cachep:
 705         btrfs_destroy_cachep();
 706 free_sysfs:
 707         btrfs_exit_sysfs();
 708         return err;
 709 }
 710
 711 static void __exit exit_btrfs_fs(void)
 712 {
 713         btrfs_destroy_cachep();
 714         extent_map_exit();
 715         extent_io_exit();
 716         btrfs_interface_exit();
 717         unregister_filesystem(&btrfs_fs_type);
 718         btrfs_exit_sysfs();
 719         btrfs_cleanup_fs_uuids();
 720         btrfs_zlib_exit();
 721 }
 722
 723 module_init(init_btrfs_fs)
 724 module_exit(exit_btrfs_fs)
 725
 726 MODULE_LICENSE("GPL");