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/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 static const struct super_operations btrfs_super_ops;
  55
  56 static void btrfs_put_super(struct super_block *sb)
  57 {
  58         struct btrfs_root *root = btrfs_sb(sb);
  59         int ret;
  60
  61         ret = close_ctree(root);
  62         sb->s_fs_info = NULL;
  63 }
  64
  65 enum {
  66         Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
  67         Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
  68         Opt_ssd, Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl,
  69         Opt_compress, Opt_compress_force, Opt_notreelog, Opt_ratio,
  70         Opt_flushoncommit,
  71         Opt_discard, 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_compress_force, "compress-force"},
  87         {Opt_ssd, "ssd"},
  88         {Opt_ssd_spread, "ssd_spread"},
  89         {Opt_nossd, "nossd"},
  90         {Opt_noacl, "noacl"},
  91         {Opt_notreelog, "notreelog"},
  92         {Opt_flushoncommit, "flushoncommit"},
  93         {Opt_ratio, "metadata_ratio=%d"},
  94         {Opt_discard, "discard"},
  95         {Opt_err, NULL},
  96 };
  97
  98 u64 btrfs_parse_size(char *str)
  99 {
 100         u64 res;
 101         int mult = 1;
 102         char *end;
 103         char last;
 104
 105         res = simple_strtoul(str, &end, 10);
 106
 107         last = end[0];
 108         if (isalpha(last)) {
 109                 last = tolower(last);
 110                 switch (last) {
 111                 case 'g':
 112                         mult *= 1024;
 113                 case 'm':
 114                         mult *= 1024;
 115                 case 'k':
 116                         mult *= 1024;
 117                 }
 118                 res = res * mult;
 119         }
 120         return res;
 121 }
 122
 123 /*
 124  * Regular mount options parser.  Everything that is needed only when
 125  * reading in a new superblock is parsed here.
 126  */
 127 int btrfs_parse_options(struct btrfs_root *root, char *options)
 128 {
 129         struct btrfs_fs_info *info = root->fs_info;
 130         substring_t args[MAX_OPT_ARGS];
 131         char *p, *num;
 132         int intarg;
 133         int ret = 0;
 134
 135         if (!options)
 136                 return 0;
 137
 138         /*
 139          * strsep changes the string, duplicate it because parse_options
 140          * gets called twice
 141          */
 142         options = kstrdup(options, GFP_NOFS);
 143         if (!options)
 144                 return -ENOMEM;
 145
 146
 147         while ((p = strsep(&options, ",")) != NULL) {
 148                 int token;
 149                 if (!*p)
 150                         continue;
 151
 152                 token = match_token(p, tokens, args);
 153                 switch (token) {
 154                 case Opt_degraded:
 155                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 156                         btrfs_set_opt(info->mount_opt, DEGRADED);
 157                         break;
 158                 case Opt_subvol:
 159                 case Opt_device:
 160                         /*
 161                          * These are parsed by btrfs_parse_early_options
 162                          * and can be happily ignored here.
 163                          */
 164                         break;
 165                 case Opt_nodatasum:
 166                         printk(KERN_INFO "btrfs: setting nodatasum\n");
 167                         btrfs_set_opt(info->mount_opt, NODATASUM);
 168                         break;
 169                 case Opt_nodatacow:
 170                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 171                         btrfs_set_opt(info->mount_opt, NODATACOW);
 172                         btrfs_set_opt(info->mount_opt, NODATASUM);
 173                         break;
 174                 case Opt_compress:
 175                         printk(KERN_INFO "btrfs: use compression\n");
 176                         btrfs_set_opt(info->mount_opt, COMPRESS);
 177                         break;
 178                 case Opt_compress_force:
 179                         printk(KERN_INFO "btrfs: forcing compression\n");
 180                         btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 181                         btrfs_set_opt(info->mount_opt, COMPRESS);
 182                         break;
 183                 case Opt_ssd:
 184                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 185                         btrfs_set_opt(info->mount_opt, SSD);
 186                         break;
 187                 case Opt_ssd_spread:
 188                         printk(KERN_INFO "btrfs: use spread ssd "
 189                                "allocation scheme\n");
 190                         btrfs_set_opt(info->mount_opt, SSD);
 191                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 192                         break;
 193                 case Opt_nossd:
 194                         printk(KERN_INFO "btrfs: not using ssd allocation "
 195                                "scheme\n");
 196                         btrfs_set_opt(info->mount_opt, NOSSD);
 197                         btrfs_clear_opt(info->mount_opt, SSD);
 198                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 199                         break;
 200                 case Opt_nobarrier:
 201                         printk(KERN_INFO "btrfs: turning off barriers\n");
 202                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 203                         break;
 204                 case Opt_thread_pool:
 205                         intarg = 0;
 206                         match_int(&args[0], &intarg);
 207                         if (intarg) {
 208                                 info->thread_pool_size = intarg;
 209                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 210                                        info->thread_pool_size);
 211                         }
 212                         break;
 213                 case Opt_max_extent:
 214                         num = match_strdup(&args[0]);
 215                         if (num) {
 216                                 info->max_extent = btrfs_parse_size(num);
 217                                 kfree(num);
 218
 219                                 info->max_extent = max_t(u64,
 220                                         info->max_extent, root->sectorsize);
 221                                 printk(KERN_INFO "btrfs: max_extent at %llu\n",
 222                                        (unsigned long long)info->max_extent);
 223                         }
 224                         break;
 225                 case Opt_max_inline:
 226                         num = match_strdup(&args[0]);
 227                         if (num) {
 228                                 info->max_inline = btrfs_parse_size(num);
 229                                 kfree(num);
 230
 231                                 if (info->max_inline) {
 232                                         info->max_inline = max_t(u64,
 233                                                 info->max_inline,
 234                                                 root->sectorsize);
 235                                 }
 236                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 237                                         (unsigned long long)info->max_inline);
 238                         }
 239                         break;
 240                 case Opt_alloc_start:
 241                         num = match_strdup(&args[0]);
 242                         if (num) {
 243                                 info->alloc_start = btrfs_parse_size(num);
 244                                 kfree(num);
 245                                 printk(KERN_INFO
 246                                         "btrfs: allocations start at %llu\n",
 247                                         (unsigned long long)info->alloc_start);
 248                         }
 249                         break;
 250                 case Opt_noacl:
 251                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 252                         break;
 253                 case Opt_notreelog:
 254                         printk(KERN_INFO "btrfs: disabling tree log\n");
 255                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 256                         break;
 257                 case Opt_flushoncommit:
 258                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 259                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 260                         break;
 261                 case Opt_ratio:
 262                         intarg = 0;
 263                         match_int(&args[0], &intarg);
 264                         if (intarg) {
 265                                 info->metadata_ratio = intarg;
 266                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 267                                        info->metadata_ratio);
 268                         }
 269                         break;
 270                 case Opt_discard:
 271                         btrfs_set_opt(info->mount_opt, DISCARD);
 272                         break;
 273                 case Opt_err:
 274                         printk(KERN_INFO "btrfs: unrecognized mount option "
 275                                "'%s'\n", p);
 276                         ret = -EINVAL;
 277                         goto out;
 278                 default:
 279                         break;
 280                 }
 281         }
 282 out:
 283         kfree(options);
 284         return ret;
 285 }
 286
 287 /*
 288  * Parse mount options that are required early in the mount process.
 289  *
 290  * All other options will be parsed on much later in the mount process and
 291  * only when we need to allocate a new super block.
 292  */
 293 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 294                 void *holder, char **subvol_name,
 295                 struct btrfs_fs_devices **fs_devices)
 296 {
 297         substring_t args[MAX_OPT_ARGS];
 298         char *opts, *p;
 299         int error = 0;
 300
 301         if (!options)
 302                 goto out;
 303
 304         /*
 305          * strsep changes the string, duplicate it because parse_options
 306          * gets called twice
 307          */
 308         opts = kstrdup(options, GFP_KERNEL);
 309         if (!opts)
 310                 return -ENOMEM;
 311
 312         while ((p = strsep(&opts, ",")) != NULL) {
 313                 int token;
 314                 if (!*p)
 315                         continue;
 316
 317                 token = match_token(p, tokens, args);
 318                 switch (token) {
 319                 case Opt_subvol:
 320                         *subvol_name = match_strdup(&args[0]);
 321                         break;
 322                 case Opt_device:
 323                         error = btrfs_scan_one_device(match_strdup(&args[0]),
 324                                         flags, holder, fs_devices);
 325                         if (error)
 326                                 goto out_free_opts;
 327                         break;
 328                 default:
 329                         break;
 330                 }
 331         }
 332
 333  out_free_opts:
 334         kfree(opts);
 335  out:
 336         /*
 337          * If no subvolume name is specified we use the default one.  Allocate
 338          * a copy of the string "." here so that code later in the
 339          * mount path doesn't care if it's the default volume or another one.
 340          */
 341         if (!*subvol_name) {
 342                 *subvol_name = kstrdup(".", GFP_KERNEL);
 343                 if (!*subvol_name)
 344                         return -ENOMEM;
 345         }
 346         return error;
 347 }
 348
 349 static int btrfs_fill_super(struct super_block *sb,
 350                             struct btrfs_fs_devices *fs_devices,
 351                             void *data, int silent)
 352 {
 353         struct inode *inode;
 354         struct dentry *root_dentry;
 355         struct btrfs_super_block *disk_super;
 356         struct btrfs_root *tree_root;
 357         struct btrfs_key key;
 358         int err;
 359
 360         sb->s_maxbytes = MAX_LFS_FILESIZE;
 361         sb->s_magic = BTRFS_SUPER_MAGIC;
 362         sb->s_op = &btrfs_super_ops;
 363         sb->s_export_op = &btrfs_export_ops;
 364         sb->s_xattr = btrfs_xattr_handlers;
 365         sb->s_time_gran = 1;
 366 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 367         sb->s_flags |= MS_POSIXACL;
 368 #endif
 369
 370         tree_root = open_ctree(sb, fs_devices, (char *)data);
 371
 372         if (IS_ERR(tree_root)) {
 373                 printk("btrfs: open_ctree failed\n");
 374                 return PTR_ERR(tree_root);
 375         }
 376         sb->s_fs_info = tree_root;
 377         disk_super = &tree_root->fs_info->super_copy;
 378
 379         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 380         key.type = BTRFS_INODE_ITEM_KEY;
 381         key.offset = 0;
 382         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root);
 383         if (IS_ERR(inode)) {
 384                 err = PTR_ERR(inode);
 385                 goto fail_close;
 386         }
 387
 388         root_dentry = d_alloc_root(inode);
 389         if (!root_dentry) {
 390                 iput(inode);
 391                 err = -ENOMEM;
 392                 goto fail_close;
 393         }
 394 #if 0
 395         /* this does the super kobj at the same time */
 396         err = btrfs_sysfs_add_super(tree_root->fs_info);
 397         if (err)
 398                 goto fail_close;
 399 #endif
 400
 401         sb->s_root = root_dentry;
 402
 403         save_mount_options(sb, data);
 404         return 0;
 405
 406 fail_close:
 407         close_ctree(tree_root);
 408         return err;
 409 }
 410
 411 int btrfs_sync_fs(struct super_block *sb, int wait)
 412 {
 413         struct btrfs_trans_handle *trans;
 414         struct btrfs_root *root = btrfs_sb(sb);
 415         int ret;
 416
 417         if (!wait) {
 418                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 419                 return 0;
 420         }
 421
 422         btrfs_start_delalloc_inodes(root, 0);
 423         btrfs_wait_ordered_extents(root, 0, 0);
 424
 425         trans = btrfs_start_transaction(root, 1);
 426         ret = btrfs_commit_transaction(trans, root);
 427         return ret;
 428 }
 429
 430 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 431 {
 432         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 433         struct btrfs_fs_info *info = root->fs_info;
 434
 435         if (btrfs_test_opt(root, DEGRADED))
 436                 seq_puts(seq, ",degraded");
 437         if (btrfs_test_opt(root, NODATASUM))
 438                 seq_puts(seq, ",nodatasum");
 439         if (btrfs_test_opt(root, NODATACOW))
 440                 seq_puts(seq, ",nodatacow");
 441         if (btrfs_test_opt(root, NOBARRIER))
 442                 seq_puts(seq, ",nobarrier");
 443         if (info->max_extent != (u64)-1)
 444                 seq_printf(seq, ",max_extent=%llu",
 445                            (unsigned long long)info->max_extent);
 446         if (info->max_inline != 8192 * 1024)
 447                 seq_printf(seq, ",max_inline=%llu",
 448                            (unsigned long long)info->max_inline);
 449         if (info->alloc_start != 0)
 450                 seq_printf(seq, ",alloc_start=%llu",
 451                            (unsigned long long)info->alloc_start);
 452         if (info->thread_pool_size !=  min_t(unsigned long,
 453                                              num_online_cpus() + 2, 8))
 454                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 455         if (btrfs_test_opt(root, COMPRESS))
 456                 seq_puts(seq, ",compress");
 457         if (btrfs_test_opt(root, NOSSD))
 458                 seq_puts(seq, ",nossd");
 459         if (btrfs_test_opt(root, SSD_SPREAD))
 460                 seq_puts(seq, ",ssd_spread");
 461         else if (btrfs_test_opt(root, SSD))
 462                 seq_puts(seq, ",ssd");
 463         if (btrfs_test_opt(root, NOTREELOG))
 464                 seq_puts(seq, ",notreelog");
 465         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 466                 seq_puts(seq, ",flushoncommit");
 467         if (btrfs_test_opt(root, DISCARD))
 468                 seq_puts(seq, ",discard");
 469         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 470                 seq_puts(seq, ",noacl");
 471         return 0;
 472 }
 473
 474 static int btrfs_test_super(struct super_block *s, void *data)
 475 {
 476         struct btrfs_fs_devices *test_fs_devices = data;
 477         struct btrfs_root *root = btrfs_sb(s);
 478
 479         return root->fs_info->fs_devices == test_fs_devices;
 480 }
 481
 482 /*
 483  * Find a superblock for the given device / mount point.
 484  *
 485  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 486  *        for multiple device setup.  Make sure to keep it in sync.
 487  */
 488 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 489                 const char *dev_name, void *data, struct vfsmount *mnt)
 490 {
 491         char *subvol_name = NULL;
 492         struct block_device *bdev = NULL;
 493         struct super_block *s;
 494         struct dentry *root;
 495         struct btrfs_fs_devices *fs_devices = NULL;
 496         fmode_t mode = FMODE_READ;
 497         int error = 0;
 498
 499         if (!(flags & MS_RDONLY))
 500                 mode |= FMODE_WRITE;
 501
 502         error = btrfs_parse_early_options(data, mode, fs_type,
 503                                           &subvol_name, &fs_devices);
 504         if (error)
 505                 return error;
 506
 507         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
 508         if (error)
 509                 goto error_free_subvol_name;
 510
 511         error = btrfs_open_devices(fs_devices, mode, fs_type);
 512         if (error)
 513                 goto error_free_subvol_name;
 514
 515         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 516                 error = -EACCES;
 517                 goto error_close_devices;
 518         }
 519
 520         bdev = fs_devices->latest_bdev;
 521         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
 522         if (IS_ERR(s))
 523                 goto error_s;
 524
 525         if (s->s_root) {
 526                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 527                         deactivate_locked_super(s);
 528                         error = -EBUSY;
 529                         goto error_close_devices;
 530                 }
 531
 532                 btrfs_close_devices(fs_devices);
 533         } else {
 534                 char b[BDEVNAME_SIZE];
 535
 536                 s->s_flags = flags;
 537                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 538                 error = btrfs_fill_super(s, fs_devices, data,
 539                                          flags & MS_SILENT ? 1 : 0);
 540                 if (error) {
 541                         deactivate_locked_super(s);
 542                         goto error_free_subvol_name;
 543                 }
 544
 545                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 546                 s->s_flags |= MS_ACTIVE;
 547         }
 548
 549         if (!strcmp(subvol_name, "."))
 550                 root = dget(s->s_root);
 551         else {
 552                 mutex_lock(&s->s_root->d_inode->i_mutex);
 553                 root = lookup_one_len(subvol_name, s->s_root,
 554                                       strlen(subvol_name));
 555                 mutex_unlock(&s->s_root->d_inode->i_mutex);
 556
 557                 if (IS_ERR(root)) {
 558                         deactivate_locked_super(s);
 559                         error = PTR_ERR(root);
 560                         goto error_free_subvol_name;
 561                 }
 562                 if (!root->d_inode) {
 563                         dput(root);
 564                         deactivate_locked_super(s);
 565                         error = -ENXIO;
 566                         goto error_free_subvol_name;
 567                 }
 568         }
 569
 570         mnt->mnt_sb = s;
 571         mnt->mnt_root = root;
 572
 573         kfree(subvol_name);
 574         return 0;
 575
 576 error_s:
 577         error = PTR_ERR(s);
 578 error_close_devices:
 579         btrfs_close_devices(fs_devices);
 580 error_free_subvol_name:
 581         kfree(subvol_name);
 582         return error;
 583 }
 584
 585 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 586 {
 587         struct btrfs_root *root = btrfs_sb(sb);
 588         int ret;
 589
 590         ret = btrfs_parse_options(root, data);
 591         if (ret)
 592                 return -EINVAL;
 593
 594         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 595                 return 0;
 596
 597         if (*flags & MS_RDONLY) {
 598                 sb->s_flags |= MS_RDONLY;
 599
 600                 ret =  btrfs_commit_super(root);
 601                 WARN_ON(ret);
 602         } else {
 603                 if (root->fs_info->fs_devices->rw_devices == 0)
 604                         return -EACCES;
 605
 606                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 607                         return -EINVAL;
 608
 609                 /* recover relocation */
 610                 ret = btrfs_recover_relocation(root);
 611                 WARN_ON(ret);
 612
 613                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 614                 WARN_ON(ret);
 615
 616                 sb->s_flags &= ~MS_RDONLY;
 617         }
 618
 619         return 0;
 620 }
 621
 622 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 623 {
 624         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 625         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 626         int bits = dentry->d_sb->s_blocksize_bits;
 627         __be32 *fsid = (__be32 *)root->fs_info->fsid;
 628
 629         buf->f_namelen = BTRFS_NAME_LEN;
 630         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 631         buf->f_bfree = buf->f_blocks -
 632                 (btrfs_super_bytes_used(disk_super) >> bits);
 633         buf->f_bavail = buf->f_bfree;
 634         buf->f_bsize = dentry->d_sb->s_blocksize;
 635         buf->f_type = BTRFS_SUPER_MAGIC;
 636
 637         /* We treat it as constant endianness (it doesn't matter _which_)
 638            because we want the fsid to come out the same whether mounted
 639            on a big-endian or little-endian host */
 640         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
 641         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
 642         /* Mask in the root object ID too, to disambiguate subvols */
 643         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
 644         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
 645
 646         return 0;
 647 }
 648
 649 static struct file_system_type btrfs_fs_type = {
 650         .owner          = THIS_MODULE,
 651         .name           = "btrfs",
 652         .get_sb         = btrfs_get_sb,
 653         .kill_sb        = kill_anon_super,
 654         .fs_flags       = FS_REQUIRES_DEV,
 655 };
 656
 657 /*
 658  * used by btrfsctl to scan devices when no FS is mounted
 659  */
 660 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 661                                 unsigned long arg)
 662 {
 663         struct btrfs_ioctl_vol_args *vol;
 664         struct btrfs_fs_devices *fs_devices;
 665         int ret = -ENOTTY;
 666
 667         if (!capable(CAP_SYS_ADMIN))
 668                 return -EPERM;
 669
 670         vol = memdup_user((void __user *)arg, sizeof(*vol));
 671         if (IS_ERR(vol))
 672                 return PTR_ERR(vol);
 673
 674         switch (cmd) {
 675         case BTRFS_IOC_SCAN_DEV:
 676                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
 677                                             &btrfs_fs_type, &fs_devices);
 678                 break;
 679         }
 680
 681         kfree(vol);
 682         return ret;
 683 }
 684
 685 static int btrfs_freeze(struct super_block *sb)
 686 {
 687         struct btrfs_root *root = btrfs_sb(sb);
 688         mutex_lock(&root->fs_info->transaction_kthread_mutex);
 689         mutex_lock(&root->fs_info->cleaner_mutex);
 690         return 0;
 691 }
 692
 693 static int btrfs_unfreeze(struct super_block *sb)
 694 {
 695         struct btrfs_root *root = btrfs_sb(sb);
 696         mutex_unlock(&root->fs_info->cleaner_mutex);
 697         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 698         return 0;
 699 }
 700
 701 static const struct super_operations btrfs_super_ops = {
 702         .drop_inode     = btrfs_drop_inode,
 703         .delete_inode   = btrfs_delete_inode,
 704         .put_super      = btrfs_put_super,
 705         .sync_fs        = btrfs_sync_fs,
 706         .show_options   = btrfs_show_options,
 707         .write_inode    = btrfs_write_inode,
 708         .dirty_inode    = btrfs_dirty_inode,
 709         .alloc_inode    = btrfs_alloc_inode,
 710         .destroy_inode  = btrfs_destroy_inode,
 711         .statfs         = btrfs_statfs,
 712         .remount_fs     = btrfs_remount,
 713         .freeze_fs      = btrfs_freeze,
 714         .unfreeze_fs    = btrfs_unfreeze,
 715 };
 716
 717 static const struct file_operations btrfs_ctl_fops = {
 718         .unlocked_ioctl  = btrfs_control_ioctl,
 719         .compat_ioctl = btrfs_control_ioctl,
 720         .owner   = THIS_MODULE,
 721 };
 722
 723 static struct miscdevice btrfs_misc = {
 724         .minor          = MISC_DYNAMIC_MINOR,
 725         .name           = "btrfs-control",
 726         .fops           = &btrfs_ctl_fops
 727 };
 728
 729 static int btrfs_interface_init(void)
 730 {
 731         return misc_register(&btrfs_misc);
 732 }
 733
 734 static void btrfs_interface_exit(void)
 735 {
 736         if (misc_deregister(&btrfs_misc) < 0)
 737                 printk(KERN_INFO "misc_deregister failed for control device");
 738 }
 739
 740 static int __init init_btrfs_fs(void)
 741 {
 742         int err;
 743
 744         err = btrfs_init_sysfs();
 745         if (err)
 746                 return err;
 747
 748         err = btrfs_init_cachep();
 749         if (err)
 750                 goto free_sysfs;
 751
 752         err = extent_io_init();
 753         if (err)
 754                 goto free_cachep;
 755
 756         err = extent_map_init();
 757         if (err)
 758                 goto free_extent_io;
 759
 760         err = btrfs_interface_init();
 761         if (err)
 762                 goto free_extent_map;
 763
 764         err = register_filesystem(&btrfs_fs_type);
 765         if (err)
 766                 goto unregister_ioctl;
 767
 768         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 769         return 0;
 770
 771 unregister_ioctl:
 772         btrfs_interface_exit();
 773 free_extent_map:
 774         extent_map_exit();
 775 free_extent_io:
 776         extent_io_exit();
 777 free_cachep:
 778         btrfs_destroy_cachep();
 779 free_sysfs:
 780         btrfs_exit_sysfs();
 781         return err;
 782 }
 783
 784 static void __exit exit_btrfs_fs(void)
 785 {
 786         btrfs_destroy_cachep();
 787         extent_map_exit();
 788         extent_io_exit();
 789         btrfs_interface_exit();
 790         unregister_filesystem(&btrfs_fs_type);
 791         btrfs_exit_sysfs();
 792         btrfs_cleanup_fs_uuids();
 793         btrfs_zlib_exit();
 794 }
 795
 796 module_init(init_btrfs_fs)
 797 module_exit(exit_btrfs_fs)
 798
 799 MODULE_LICENSE("GPL");