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/seq_file.h>
  28 #include <linux/string.h>
  29 #include <linux/smp_lock.h>
  30 #include <linux/backing-dev.h>
  31 #include <linux/mount.h>
  32 #include <linux/mpage.h>
  33 #include <linux/swap.h>
  34 #include <linux/writeback.h>
  35 #include <linux/statfs.h>
  36 #include <linux/compat.h>
  37 #include <linux/parser.h>
  38 #include <linux/ctype.h>
  39 #include <linux/namei.h>
  40 #include <linux/miscdevice.h>
  41 #include <linux/magic.h>
  42 #include "compat.h"
  43 #include "ctree.h"
  44 #include "disk-io.h"
  45 #include "transaction.h"
  46 #include "btrfs_inode.h"
  47 #include "ioctl.h"
  48 #include "print-tree.h"
  49 #include "xattr.h"
  50 #include "volumes.h"
  51 #include "version.h"
  52 #include "export.h"
  53 #include "compression.h"
  54
  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         int ret;
  62
  63         ret = close_ctree(root);
  64         sb->s_fs_info = NULL;
  65 }
  66
  67 enum {
  68         Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
  69         Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
  70         Opt_ssd, Opt_thread_pool, Opt_noacl,  Opt_compress, Opt_notreelog,
  71         Opt_ratio, Opt_flushoncommit, Opt_err,
  72 };
  73
  74 static match_table_t tokens = {
  75         {Opt_degraded, "degraded"},
  76         {Opt_subvol, "subvol=%s"},
  77         {Opt_device, "device=%s"},
  78         {Opt_nodatasum, "nodatasum"},
  79         {Opt_nodatacow, "nodatacow"},
  80         {Opt_nobarrier, "nobarrier"},
  81         {Opt_max_extent, "max_extent=%s"},
  82         {Opt_max_inline, "max_inline=%s"},
  83         {Opt_alloc_start, "alloc_start=%s"},
  84         {Opt_thread_pool, "thread_pool=%d"},
  85         {Opt_compress, "compress"},
  86         {Opt_ssd, "ssd"},
  87         {Opt_noacl, "noacl"},
  88         {Opt_notreelog, "notreelog"},
  89         {Opt_flushoncommit, "flushoncommit"},
  90         {Opt_ratio, "metadata_ratio=%d"},
  91         {Opt_err, NULL},
  92 };
  93
  94 u64 btrfs_parse_size(char *str)
  95 {
  96         u64 res;
  97         int mult = 1;
  98         char *end;
  99         char last;
 100
 101         res = simple_strtoul(str, &end, 10);
 102
 103         last = end[0];
 104         if (isalpha(last)) {
 105                 last = tolower(last);
 106                 switch (last) {
 107                 case 'g':
 108                         mult *= 1024;
 109                 case 'm':
 110                         mult *= 1024;
 111                 case 'k':
 112                         mult *= 1024;
 113                 }
 114                 res = res * mult;
 115         }
 116         return res;
 117 }
 118
 119 /*
 120  * Regular mount options parser.  Everything that is needed only when
 121  * reading in a new superblock is parsed here.
 122  */
 123 int btrfs_parse_options(struct btrfs_root *root, char *options)
 124 {
 125         struct btrfs_fs_info *info = root->fs_info;
 126         substring_t args[MAX_OPT_ARGS];
 127         char *p, *num;
 128         int intarg;
 129
 130         if (!options)
 131                 return 0;
 132
 133         /*
 134          * strsep changes the string, duplicate it because parse_options
 135          * gets called twice
 136          */
 137         options = kstrdup(options, GFP_NOFS);
 138         if (!options)
 139                 return -ENOMEM;
 140
 141
 142         while ((p = strsep(&options, ",")) != NULL) {
 143                 int token;
 144                 if (!*p)
 145                         continue;
 146
 147                 token = match_token(p, tokens, args);
 148                 switch (token) {
 149                 case Opt_degraded:
 150                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 151                         btrfs_set_opt(info->mount_opt, DEGRADED);
 152                         break;
 153                 case Opt_subvol:
 154                 case Opt_device:
 155                         /*
 156                          * These are parsed by btrfs_parse_early_options
 157                          * and can be happily ignored here.
 158                          */
 159                         break;
 160                 case Opt_nodatasum:
 161                         printk(KERN_INFO "btrfs: setting nodatacsum\n");
 162                         btrfs_set_opt(info->mount_opt, NODATASUM);
 163                         break;
 164                 case Opt_nodatacow:
 165                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 166                         btrfs_set_opt(info->mount_opt, NODATACOW);
 167                         btrfs_set_opt(info->mount_opt, NODATASUM);
 168                         break;
 169                 case Opt_compress:
 170                         printk(KERN_INFO "btrfs: use compression\n");
 171                         btrfs_set_opt(info->mount_opt, COMPRESS);
 172                         break;
 173                 case Opt_ssd:
 174                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 175                         btrfs_set_opt(info->mount_opt, SSD);
 176                         break;
 177                 case Opt_nobarrier:
 178                         printk(KERN_INFO "btrfs: turning off barriers\n");
 179                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 180                         break;
 181                 case Opt_thread_pool:
 182                         intarg = 0;
 183                         match_int(&args[0], &intarg);
 184                         if (intarg) {
 185                                 info->thread_pool_size = intarg;
 186                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 187                                        info->thread_pool_size);
 188                         }
 189                         break;
 190                 case Opt_max_extent:
 191                         num = match_strdup(&args[0]);
 192                         if (num) {
 193                                 info->max_extent = btrfs_parse_size(num);
 194                                 kfree(num);
 195
 196                                 info->max_extent = max_t(u64,
 197                                         info->max_extent, root->sectorsize);
 198                                 printk(KERN_INFO "btrfs: max_extent at %llu\n",
 199                                        (unsigned long long)info->max_extent);
 200                         }
 201                         break;
 202                 case Opt_max_inline:
 203                         num = match_strdup(&args[0]);
 204                         if (num) {
 205                                 info->max_inline = btrfs_parse_size(num);
 206                                 kfree(num);
 207
 208                                 if (info->max_inline) {
 209                                         info->max_inline = max_t(u64,
 210                                                 info->max_inline,
 211                                                 root->sectorsize);
 212                                 }
 213                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 214                                         (unsigned long long)info->max_inline);
 215                         }
 216                         break;
 217                 case Opt_alloc_start:
 218                         num = match_strdup(&args[0]);
 219                         if (num) {
 220                                 info->alloc_start = btrfs_parse_size(num);
 221                                 kfree(num);
 222                                 printk(KERN_INFO
 223                                         "btrfs: allocations start at %llu\n",
 224                                         (unsigned long long)info->alloc_start);
 225                         }
 226                         break;
 227                 case Opt_noacl:
 228                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 229                         break;
 230                 case Opt_notreelog:
 231                         printk(KERN_INFO "btrfs: disabling tree log\n");
 232                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 233                         break;
 234                 case Opt_flushoncommit:
 235                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 236                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 237                         break;
 238                 case Opt_ratio:
 239                         intarg = 0;
 240                         match_int(&args[0], &intarg);
 241                         if (intarg) {
 242                                 info->metadata_ratio = intarg;
 243                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 244                                        info->metadata_ratio);
 245                         }
 246                         break;
 247                 default:
 248                         break;
 249                 }
 250         }
 251         kfree(options);
 252         return 0;
 253 }
 254
 255 /*
 256  * Parse mount options that are required early in the mount process.
 257  *
 258  * All other options will be parsed on much later in the mount process and
 259  * only when we need to allocate a new super block.
 260  */
 261 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 262                 void *holder, char **subvol_name,
 263                 struct btrfs_fs_devices **fs_devices)
 264 {
 265         substring_t args[MAX_OPT_ARGS];
 266         char *opts, *p;
 267         int error = 0;
 268
 269         if (!options)
 270                 goto out;
 271
 272         /*
 273          * strsep changes the string, duplicate it because parse_options
 274          * gets called twice
 275          */
 276         opts = kstrdup(options, GFP_KERNEL);
 277         if (!opts)
 278                 return -ENOMEM;
 279
 280         while ((p = strsep(&opts, ",")) != NULL) {
 281                 int token;
 282                 if (!*p)
 283                         continue;
 284
 285                 token = match_token(p, tokens, args);
 286                 switch (token) {
 287                 case Opt_subvol:
 288                         *subvol_name = match_strdup(&args[0]);
 289                         break;
 290                 case Opt_device:
 291                         error = btrfs_scan_one_device(match_strdup(&args[0]),
 292                                         flags, holder, fs_devices);
 293                         if (error)
 294                                 goto out_free_opts;
 295                         break;
 296                 default:
 297                         break;
 298                 }
 299         }
 300
 301  out_free_opts:
 302         kfree(opts);
 303  out:
 304         /*
 305          * If no subvolume name is specified we use the default one.  Allocate
 306          * a copy of the string "." here so that code later in the
 307          * mount path doesn't care if it's the default volume or another one.
 308          */
 309         if (!*subvol_name) {
 310                 *subvol_name = kstrdup(".", GFP_KERNEL);
 311                 if (!*subvol_name)
 312                         return -ENOMEM;
 313         }
 314         return error;
 315 }
 316
 317 static int btrfs_fill_super(struct super_block *sb,
 318                             struct btrfs_fs_devices *fs_devices,
 319                             void *data, int silent)
 320 {
 321         struct inode *inode;
 322         struct dentry *root_dentry;
 323         struct btrfs_super_block *disk_super;
 324         struct btrfs_root *tree_root;
 325         struct btrfs_inode *bi;
 326         int err;
 327
 328         sb->s_maxbytes = MAX_LFS_FILESIZE;
 329         sb->s_magic = BTRFS_SUPER_MAGIC;
 330         sb->s_op = &btrfs_super_ops;
 331         sb->s_export_op = &btrfs_export_ops;
 332         sb->s_xattr = btrfs_xattr_handlers;
 333         sb->s_time_gran = 1;
 334         sb->s_flags |= MS_POSIXACL;
 335
 336         tree_root = open_ctree(sb, fs_devices, (char *)data);
 337
 338         if (IS_ERR(tree_root)) {
 339                 printk("btrfs: open_ctree failed\n");
 340                 return PTR_ERR(tree_root);
 341         }
 342         sb->s_fs_info = tree_root;
 343         disk_super = &tree_root->fs_info->super_copy;
 344         inode = btrfs_iget_locked(sb, BTRFS_FIRST_FREE_OBJECTID,
 345                                   tree_root->fs_info->fs_root);
 346         bi = BTRFS_I(inode);
 347         bi->location.objectid = inode->i_ino;
 348         bi->location.offset = 0;
 349         bi->root = tree_root->fs_info->fs_root;
 350
 351         btrfs_set_key_type(&bi->location, BTRFS_INODE_ITEM_KEY);
 352
 353         if (!inode) {
 354                 err = -ENOMEM;
 355                 goto fail_close;
 356         }
 357         if (inode->i_state & I_NEW) {
 358                 btrfs_read_locked_inode(inode);
 359                 unlock_new_inode(inode);
 360         }
 361
 362         root_dentry = d_alloc_root(inode);
 363         if (!root_dentry) {
 364                 iput(inode);
 365                 err = -ENOMEM;
 366                 goto fail_close;
 367         }
 368 #if 0
 369         /* this does the super kobj at the same time */
 370         err = btrfs_sysfs_add_super(tree_root->fs_info);
 371         if (err)
 372                 goto fail_close;
 373 #endif
 374
 375         sb->s_root = root_dentry;
 376
 377         save_mount_options(sb, data);
 378         return 0;
 379
 380 fail_close:
 381         close_ctree(tree_root);
 382         return err;
 383 }
 384
 385 int btrfs_sync_fs(struct super_block *sb, int wait)
 386 {
 387         struct btrfs_trans_handle *trans;
 388         struct btrfs_root *root = btrfs_sb(sb);
 389         int ret;
 390
 391         if (sb->s_flags & MS_RDONLY)
 392                 return 0;
 393
 394         sb->s_dirt = 0;
 395         if (!wait) {
 396                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 397                 return 0;
 398         }
 399
 400         btrfs_start_delalloc_inodes(root);
 401         btrfs_wait_ordered_extents(root, 0);
 402
 403         trans = btrfs_start_transaction(root, 1);
 404         ret = btrfs_commit_transaction(trans, root);
 405         sb->s_dirt = 0;
 406         return ret;
 407 }
 408
 409 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 410 {
 411         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 412         struct btrfs_fs_info *info = root->fs_info;
 413
 414         if (btrfs_test_opt(root, DEGRADED))
 415                 seq_puts(seq, ",degraded");
 416         if (btrfs_test_opt(root, NODATASUM))
 417                 seq_puts(seq, ",nodatasum");
 418         if (btrfs_test_opt(root, NODATACOW))
 419                 seq_puts(seq, ",nodatacow");
 420         if (btrfs_test_opt(root, NOBARRIER))
 421                 seq_puts(seq, ",nobarrier");
 422         if (info->max_extent != (u64)-1)
 423                 seq_printf(seq, ",max_extent=%llu",
 424                            (unsigned long long)info->max_extent);
 425         if (info->max_inline != 8192 * 1024)
 426                 seq_printf(seq, ",max_inline=%llu",
 427                            (unsigned long long)info->max_inline);
 428         if (info->alloc_start != 0)
 429                 seq_printf(seq, ",alloc_start=%llu",
 430                            (unsigned long long)info->alloc_start);
 431         if (info->thread_pool_size !=  min_t(unsigned long,
 432                                              num_online_cpus() + 2, 8))
 433                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 434         if (btrfs_test_opt(root, COMPRESS))
 435                 seq_puts(seq, ",compress");
 436         if (btrfs_test_opt(root, SSD))
 437                 seq_puts(seq, ",ssd");
 438         if (btrfs_test_opt(root, NOTREELOG))
 439                 seq_puts(seq, ",no-treelog");
 440         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 441                 seq_puts(seq, ",flush-on-commit");
 442         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 443                 seq_puts(seq, ",noacl");
 444         return 0;
 445 }
 446
 447 static void btrfs_write_super(struct super_block *sb)
 448 {
 449         sb->s_dirt = 0;
 450 }
 451
 452 static int btrfs_test_super(struct super_block *s, void *data)
 453 {
 454         struct btrfs_fs_devices *test_fs_devices = data;
 455         struct btrfs_root *root = btrfs_sb(s);
 456
 457         return root->fs_info->fs_devices == test_fs_devices;
 458 }
 459
 460 /*
 461  * Find a superblock for the given device / mount point.
 462  *
 463  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 464  *        for multiple device setup.  Make sure to keep it in sync.
 465  */
 466 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 467                 const char *dev_name, void *data, struct vfsmount *mnt)
 468 {
 469         char *subvol_name = NULL;
 470         struct block_device *bdev = NULL;
 471         struct super_block *s;
 472         struct dentry *root;
 473         struct btrfs_fs_devices *fs_devices = NULL;
 474         fmode_t mode = FMODE_READ;
 475         int error = 0;
 476
 477         if (!(flags & MS_RDONLY))
 478                 mode |= FMODE_WRITE;
 479
 480         error = btrfs_parse_early_options(data, mode, fs_type,
 481                                           &subvol_name, &fs_devices);
 482         if (error)
 483                 return error;
 484
 485         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
 486         if (error)
 487                 goto error_free_subvol_name;
 488
 489         error = btrfs_open_devices(fs_devices, mode, fs_type);
 490         if (error)
 491                 goto error_free_subvol_name;
 492
 493         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 494                 error = -EACCES;
 495                 goto error_close_devices;
 496         }
 497
 498         bdev = fs_devices->latest_bdev;
 499         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
 500         if (IS_ERR(s))
 501                 goto error_s;
 502
 503         if (s->s_root) {
 504                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 505                         up_write(&s->s_umount);
 506                         deactivate_super(s);
 507                         error = -EBUSY;
 508                         goto error_close_devices;
 509                 }
 510
 511                 btrfs_close_devices(fs_devices);
 512         } else {
 513                 char b[BDEVNAME_SIZE];
 514
 515                 s->s_flags = flags;
 516                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 517                 error = btrfs_fill_super(s, fs_devices, data,
 518                                          flags & MS_SILENT ? 1 : 0);
 519                 if (error) {
 520                         up_write(&s->s_umount);
 521                         deactivate_super(s);
 522                         goto error_free_subvol_name;
 523                 }
 524
 525                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 526                 s->s_flags |= MS_ACTIVE;
 527         }
 528
 529         if (!strcmp(subvol_name, "."))
 530                 root = dget(s->s_root);
 531         else {
 532                 mutex_lock(&s->s_root->d_inode->i_mutex);
 533                 root = lookup_one_len(subvol_name, s->s_root,
 534                                       strlen(subvol_name));
 535                 mutex_unlock(&s->s_root->d_inode->i_mutex);
 536
 537                 if (IS_ERR(root)) {
 538                         up_write(&s->s_umount);
 539                         deactivate_super(s);
 540                         error = PTR_ERR(root);
 541                         goto error_free_subvol_name;
 542                 }
 543                 if (!root->d_inode) {
 544                         dput(root);
 545                         up_write(&s->s_umount);
 546                         deactivate_super(s);
 547                         error = -ENXIO;
 548                         goto error_free_subvol_name;
 549                 }
 550         }
 551
 552         mnt->mnt_sb = s;
 553         mnt->mnt_root = root;
 554
 555         kfree(subvol_name);
 556         return 0;
 557
 558 error_s:
 559         error = PTR_ERR(s);
 560 error_close_devices:
 561         btrfs_close_devices(fs_devices);
 562 error_free_subvol_name:
 563         kfree(subvol_name);
 564         return error;
 565 }
 566
 567 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 568 {
 569         struct btrfs_root *root = btrfs_sb(sb);
 570         int ret;
 571
 572         ret = btrfs_parse_options(root, data);
 573         if (ret)
 574                 return -EINVAL;
 575
 576         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 577                 return 0;
 578
 579         if (*flags & MS_RDONLY) {
 580                 sb->s_flags |= MS_RDONLY;
 581
 582                 ret =  btrfs_commit_super(root);
 583                 WARN_ON(ret);
 584         } else {
 585                 if (root->fs_info->fs_devices->rw_devices == 0)
 586                         return -EACCES;
 587
 588                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 589                         return -EINVAL;
 590
 591                 ret = btrfs_cleanup_reloc_trees(root);
 592                 WARN_ON(ret);
 593
 594                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 595                 WARN_ON(ret);
 596
 597                 sb->s_flags &= ~MS_RDONLY;
 598         }
 599
 600         return 0;
 601 }
 602
 603 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 604 {
 605         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 606         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 607         int bits = dentry->d_sb->s_blocksize_bits;
 608         __be32 *fsid = (__be32 *)root->fs_info->fsid;
 609
 610         buf->f_namelen = BTRFS_NAME_LEN;
 611         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 612         buf->f_bfree = buf->f_blocks -
 613                 (btrfs_super_bytes_used(disk_super) >> bits);
 614         buf->f_bavail = buf->f_bfree;
 615         buf->f_bsize = dentry->d_sb->s_blocksize;
 616         buf->f_type = BTRFS_SUPER_MAGIC;
 617
 618         /* We treat it as constant endianness (it doesn't matter _which_)
 619            because we want the fsid to come out the same whether mounted
 620            on a big-endian or little-endian host */
 621         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
 622         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
 623         /* Mask in the root object ID too, to disambiguate subvols */
 624         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
 625         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
 626
 627         return 0;
 628 }
 629
 630 static struct file_system_type btrfs_fs_type = {
 631         .owner          = THIS_MODULE,
 632         .name           = "btrfs",
 633         .get_sb         = btrfs_get_sb,
 634         .kill_sb        = kill_anon_super,
 635         .fs_flags       = FS_REQUIRES_DEV,
 636 };
 637
 638 /*
 639  * used by btrfsctl to scan devices when no FS is mounted
 640  */
 641 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 642                                 unsigned long arg)
 643 {
 644         struct btrfs_ioctl_vol_args *vol;
 645         struct btrfs_fs_devices *fs_devices;
 646         int ret = -ENOTTY;
 647
 648         if (!capable(CAP_SYS_ADMIN))
 649                 return -EPERM;
 650
 651         vol = memdup_user((void __user *)arg, sizeof(*vol));
 652         if (IS_ERR(vol))
 653                 return PTR_ERR(vol);
 654
 655         switch (cmd) {
 656         case BTRFS_IOC_SCAN_DEV:
 657                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
 658                                             &btrfs_fs_type, &fs_devices);
 659                 break;
 660         }
 661
 662         kfree(vol);
 663         return ret;
 664 }
 665
 666 static int btrfs_freeze(struct super_block *sb)
 667 {
 668         struct btrfs_root *root = btrfs_sb(sb);
 669         mutex_lock(&root->fs_info->transaction_kthread_mutex);
 670         mutex_lock(&root->fs_info->cleaner_mutex);
 671         return 0;
 672 }
 673
 674 static int btrfs_unfreeze(struct super_block *sb)
 675 {
 676         struct btrfs_root *root = btrfs_sb(sb);
 677         mutex_unlock(&root->fs_info->cleaner_mutex);
 678         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 679         return 0;
 680 }
 681
 682 static struct super_operations btrfs_super_ops = {
 683         .delete_inode   = btrfs_delete_inode,
 684         .put_super      = btrfs_put_super,
 685         .write_super    = btrfs_write_super,
 686         .sync_fs        = btrfs_sync_fs,
 687         .show_options   = btrfs_show_options,
 688         .write_inode    = btrfs_write_inode,
 689         .dirty_inode    = btrfs_dirty_inode,
 690         .alloc_inode    = btrfs_alloc_inode,
 691         .destroy_inode  = btrfs_destroy_inode,
 692         .statfs         = btrfs_statfs,
 693         .remount_fs     = btrfs_remount,
 694         .freeze_fs      = btrfs_freeze,
 695         .unfreeze_fs    = btrfs_unfreeze,
 696 };
 697
 698 static const struct file_operations btrfs_ctl_fops = {
 699         .unlocked_ioctl  = btrfs_control_ioctl,
 700         .compat_ioctl = btrfs_control_ioctl,
 701         .owner   = THIS_MODULE,
 702 };
 703
 704 static struct miscdevice btrfs_misc = {
 705         .minor          = MISC_DYNAMIC_MINOR,
 706         .name           = "btrfs-control",
 707         .fops           = &btrfs_ctl_fops
 708 };
 709
 710 static int btrfs_interface_init(void)
 711 {
 712         return misc_register(&btrfs_misc);
 713 }
 714
 715 static void btrfs_interface_exit(void)
 716 {
 717         if (misc_deregister(&btrfs_misc) < 0)
 718                 printk(KERN_INFO "misc_deregister failed for control device");
 719 }
 720
 721 static int __init init_btrfs_fs(void)
 722 {
 723         int err;
 724
 725         err = btrfs_init_sysfs();
 726         if (err)
 727                 return err;
 728
 729         err = btrfs_init_cachep();
 730         if (err)
 731                 goto free_sysfs;
 732
 733         err = extent_io_init();
 734         if (err)
 735                 goto free_cachep;
 736
 737         err = extent_map_init();
 738         if (err)
 739                 goto free_extent_io;
 740
 741         err = btrfs_interface_init();
 742         if (err)
 743                 goto free_extent_map;
 744
 745         err = register_filesystem(&btrfs_fs_type);
 746         if (err)
 747                 goto unregister_ioctl;
 748
 749         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 750         return 0;
 751
 752 unregister_ioctl:
 753         btrfs_interface_exit();
 754 free_extent_map:
 755         extent_map_exit();
 756 free_extent_io:
 757         extent_io_exit();
 758 free_cachep:
 759         btrfs_destroy_cachep();
 760 free_sysfs:
 761         btrfs_exit_sysfs();
 762         return err;
 763 }
 764
 765 static void __exit exit_btrfs_fs(void)
 766 {
 767         btrfs_destroy_cachep();
 768         extent_map_exit();
 769         extent_io_exit();
 770         btrfs_interface_exit();
 771         unregister_filesystem(&btrfs_fs_type);
 772         btrfs_exit_sysfs();
 773         btrfs_cleanup_fs_uuids();
 774         btrfs_zlib_exit();
 775 }
 776
 777 module_init(init_btrfs_fs)
 778 module_exit(exit_btrfs_fs)
 779
 780 MODULE_LICENSE("GPL");