git.oblomov.eu Git - linux-2.6/blob - 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 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_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl,
  70         Opt_compress, Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_err,
  71 };
  72
  73 static match_table_t tokens = {
  74         {Opt_degraded, "degraded"},
  75         {Opt_subvol, "subvol=%s"},
  76         {Opt_device, "device=%s"},
  77         {Opt_nodatasum, "nodatasum"},
  78         {Opt_nodatacow, "nodatacow"},
  79         {Opt_nobarrier, "nobarrier"},
  80         {Opt_max_extent, "max_extent=%s"},
  81         {Opt_max_inline, "max_inline=%s"},
  82         {Opt_alloc_start, "alloc_start=%s"},
  83         {Opt_thread_pool, "thread_pool=%d"},
  84         {Opt_compress, "compress"},
  85         {Opt_ssd, "ssd"},
  86         {Opt_ssd_spread, "ssd_spread"},
  87         {Opt_nossd, "nossd"},
  88         {Opt_noacl, "noacl"},
  89         {Opt_notreelog, "notreelog"},
  90         {Opt_flushoncommit, "flushoncommit"},
  91         {Opt_ratio, "metadata_ratio=%d"},
  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 nodatasum\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_ssd_spread:
 179                         printk(KERN_INFO "btrfs: use spread ssd "
 180                                "allocation scheme\n");
 181                         btrfs_set_opt(info->mount_opt, SSD);
 182                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 183                         break;
 184                 case Opt_nossd:
 185                         printk(KERN_INFO "btrfs: not using ssd allocation "
 186                                "scheme\n");
 187                         btrfs_set_opt(info->mount_opt, NOSSD);
 188                         btrfs_clear_opt(info->mount_opt, SSD);
 189                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 190                         break;
 191                 case Opt_nobarrier:
 192                         printk(KERN_INFO "btrfs: turning off barriers\n");
 193                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 194                         break;
 195                 case Opt_thread_pool:
 196                         intarg = 0;
 197                         match_int(&args[0], &intarg);
 198                         if (intarg) {
 199                                 info->thread_pool_size = intarg;
 200                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 201                                        info->thread_pool_size);
 202                         }
 203                         break;
 204                 case Opt_max_extent:
 205                         num = match_strdup(&args[0]);
 206                         if (num) {
 207                                 info->max_extent = btrfs_parse_size(num);
 208                                 kfree(num);
 209
 210                                 info->max_extent = max_t(u64,
 211                                         info->max_extent, root->sectorsize);
 212                                 printk(KERN_INFO "btrfs: max_extent at %llu\n",
 213                                        (unsigned long long)info->max_extent);
 214                         }
 215                         break;
 216                 case Opt_max_inline:
 217                         num = match_strdup(&args[0]);
 218                         if (num) {
 219                                 info->max_inline = btrfs_parse_size(num);
 220                                 kfree(num);
 221
 222                                 if (info->max_inline) {
 223                                         info->max_inline = max_t(u64,
 224                                                 info->max_inline,
 225                                                 root->sectorsize);
 226                                 }
 227                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 228                                         (unsigned long long)info->max_inline);
 229                         }
 230                         break;
 231                 case Opt_alloc_start:
 232                         num = match_strdup(&args[0]);
 233                         if (num) {
 234                                 info->alloc_start = btrfs_parse_size(num);
 235                                 kfree(num);
 236                                 printk(KERN_INFO
 237                                         "btrfs: allocations start at %llu\n",
 238                                         (unsigned long long)info->alloc_start);
 239                         }
 240                         break;
 241                 case Opt_noacl:
 242                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 243                         break;
 244                 case Opt_notreelog:
 245                         printk(KERN_INFO "btrfs: disabling tree log\n");
 246                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 247                         break;
 248                 case Opt_flushoncommit:
 249                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 250                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 251                         break;
 252                 case Opt_ratio:
 253                         intarg = 0;
 254                         match_int(&args[0], &intarg);
 255                         if (intarg) {
 256                                 info->metadata_ratio = intarg;
 257                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 258                                        info->metadata_ratio);
 259                         }
 260                         break;
 261                 default:
 262                         break;
 263                 }
 264         }
 265         kfree(options);
 266         return 0;
 267 }
 268
 269 /*
 270  * Parse mount options that are required early in the mount process.
 271  *
 272  * All other options will be parsed on much later in the mount process and
 273  * only when we need to allocate a new super block.
 274  */
 275 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 276                 void *holder, char **subvol_name,
 277                 struct btrfs_fs_devices **fs_devices)
 278 {
 279         substring_t args[MAX_OPT_ARGS];
 280         char *opts, *p;
 281         int error = 0;
 282
 283         if (!options)
 284                 goto out;
 285
 286         /*
 287          * strsep changes the string, duplicate it because parse_options
 288          * gets called twice
 289          */
 290         opts = kstrdup(options, GFP_KERNEL);
 291         if (!opts)
 292                 return -ENOMEM;
 293
 294         while ((p = strsep(&opts, ",")) != NULL) {
 295                 int token;
 296                 if (!*p)
 297                         continue;
 298
 299                 token = match_token(p, tokens, args);
 300                 switch (token) {
 301                 case Opt_subvol:
 302                         *subvol_name = match_strdup(&args[0]);
 303                         break;
 304                 case Opt_device:
 305                         error = btrfs_scan_one_device(match_strdup(&args[0]),
 306                                         flags, holder, fs_devices);
 307                         if (error)
 308                                 goto out_free_opts;
 309                         break;
 310                 default:
 311                         break;
 312                 }
 313         }
 314
 315  out_free_opts:
 316         kfree(opts);
 317  out:
 318         /*
 319          * If no subvolume name is specified we use the default one.  Allocate
 320          * a copy of the string "." here so that code later in the
 321          * mount path doesn't care if it's the default volume or another one.
 322          */
 323         if (!*subvol_name) {
 324                 *subvol_name = kstrdup(".", GFP_KERNEL);
 325                 if (!*subvol_name)
 326                         return -ENOMEM;
 327         }
 328         return error;
 329 }
 330
 331 static int btrfs_fill_super(struct super_block *sb,
 332                             struct btrfs_fs_devices *fs_devices,
 333                             void *data, int silent)
 334 {
 335         struct inode *inode;
 336         struct dentry *root_dentry;
 337         struct btrfs_super_block *disk_super;
 338         struct btrfs_root *tree_root;
 339         struct btrfs_key key;
 340         int err;
 341
 342         sb->s_maxbytes = MAX_LFS_FILESIZE;
 343         sb->s_magic = BTRFS_SUPER_MAGIC;
 344         sb->s_op = &btrfs_super_ops;
 345         sb->s_export_op = &btrfs_export_ops;
 346         sb->s_xattr = btrfs_xattr_handlers;
 347         sb->s_time_gran = 1;
 348         sb->s_flags |= MS_POSIXACL;
 349
 350         tree_root = open_ctree(sb, fs_devices, (char *)data);
 351
 352         if (IS_ERR(tree_root)) {
 353                 printk("btrfs: open_ctree failed\n");
 354                 return PTR_ERR(tree_root);
 355         }
 356         sb->s_fs_info = tree_root;
 357         disk_super = &tree_root->fs_info->super_copy;
 358
 359         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 360         key.type = BTRFS_INODE_ITEM_KEY;
 361         key.offset = 0;
 362         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root);
 363         if (IS_ERR(inode)) {
 364                 err = PTR_ERR(inode);
 365                 goto fail_close;
 366         }
 367
 368         root_dentry = d_alloc_root(inode);
 369         if (!root_dentry) {
 370                 iput(inode);
 371                 err = -ENOMEM;
 372                 goto fail_close;
 373         }
 374 #if 0
 375         /* this does the super kobj at the same time */
 376         err = btrfs_sysfs_add_super(tree_root->fs_info);
 377         if (err)
 378                 goto fail_close;
 379 #endif
 380
 381         sb->s_root = root_dentry;
 382
 383         save_mount_options(sb, data);
 384         return 0;
 385
 386 fail_close:
 387         close_ctree(tree_root);
 388         return err;
 389 }
 390
 391 int btrfs_sync_fs(struct super_block *sb, int wait)
 392 {
 393         struct btrfs_trans_handle *trans;
 394         struct btrfs_root *root = btrfs_sb(sb);
 395         int ret;
 396
 397         if (!wait) {
 398                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 399                 return 0;
 400         }
 401
 402         btrfs_start_delalloc_inodes(root);
 403         btrfs_wait_ordered_extents(root, 0);
 404
 405         trans = btrfs_start_transaction(root, 1);
 406         ret = btrfs_commit_transaction(trans, root);
 407         return ret;
 408 }
 409
 410 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 411 {
 412         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 413         struct btrfs_fs_info *info = root->fs_info;
 414
 415         if (btrfs_test_opt(root, DEGRADED))
 416                 seq_puts(seq, ",degraded");
 417         if (btrfs_test_opt(root, NODATASUM))
 418                 seq_puts(seq, ",nodatasum");
 419         if (btrfs_test_opt(root, NODATACOW))
 420                 seq_puts(seq, ",nodatacow");
 421         if (btrfs_test_opt(root, NOBARRIER))
 422                 seq_puts(seq, ",nobarrier");
 423         if (info->max_extent != (u64)-1)
 424                 seq_printf(seq, ",max_extent=%llu",
 425                            (unsigned long long)info->max_extent);
 426         if (info->max_inline != 8192 * 1024)
 427                 seq_printf(seq, ",max_inline=%llu",
 428                            (unsigned long long)info->max_inline);
 429         if (info->alloc_start != 0)
 430                 seq_printf(seq, ",alloc_start=%llu",
 431                            (unsigned long long)info->alloc_start);
 432         if (info->thread_pool_size !=  min_t(unsigned long,
 433                                              num_online_cpus() + 2, 8))
 434                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 435         if (btrfs_test_opt(root, COMPRESS))
 436                 seq_puts(seq, ",compress");
 437         if (btrfs_test_opt(root, NOSSD))
 438                 seq_puts(seq, ",nossd");
 439         if (btrfs_test_opt(root, SSD_SPREAD))
 440                 seq_puts(seq, ",ssd_spread");
 441         else if (btrfs_test_opt(root, SSD))
 442                 seq_puts(seq, ",ssd");
 443         if (btrfs_test_opt(root, NOTREELOG))
 444                 seq_puts(seq, ",notreelog");
 445         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 446                 seq_puts(seq, ",flushoncommit");
 447         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 448                 seq_puts(seq, ",noacl");
 449         return 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                         deactivate_locked_super(s);
 506                         error = -EBUSY;
 507                         goto error_close_devices;
 508                 }
 509
 510                 btrfs_close_devices(fs_devices);
 511         } else {
 512                 char b[BDEVNAME_SIZE];
 513
 514                 s->s_flags = flags;
 515                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 516                 error = btrfs_fill_super(s, fs_devices, data,
 517                                          flags & MS_SILENT ? 1 : 0);
 518                 if (error) {
 519                         deactivate_locked_super(s);
 520                         goto error_free_subvol_name;
 521                 }
 522
 523                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 524                 s->s_flags |= MS_ACTIVE;
 525         }
 526
 527         if (!strcmp(subvol_name, "."))
 528                 root = dget(s->s_root);
 529         else {
 530                 mutex_lock(&s->s_root->d_inode->i_mutex);
 531                 root = lookup_one_len(subvol_name, s->s_root,
 532                                       strlen(subvol_name));
 533                 mutex_unlock(&s->s_root->d_inode->i_mutex);
 534
 535                 if (IS_ERR(root)) {
 536                         deactivate_locked_super(s);
 537                         error = PTR_ERR(root);
 538                         goto error_free_subvol_name;
 539                 }
 540                 if (!root->d_inode) {
 541                         dput(root);
 542                         deactivate_locked_super(s);
 543                         error = -ENXIO;
 544                         goto error_free_subvol_name;
 545                 }
 546         }
 547
 548         mnt->mnt_sb = s;
 549         mnt->mnt_root = root;
 550
 551         kfree(subvol_name);
 552         return 0;
 553
 554 error_s:
 555         error = PTR_ERR(s);
 556 error_close_devices:
 557         btrfs_close_devices(fs_devices);
 558 error_free_subvol_name:
 559         kfree(subvol_name);
 560         return error;
 561 }
 562
 563 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 564 {
 565         struct btrfs_root *root = btrfs_sb(sb);
 566         int ret;
 567
 568         ret = btrfs_parse_options(root, data);
 569         if (ret)
 570                 return -EINVAL;
 571
 572         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 573                 return 0;
 574
 575         if (*flags & MS_RDONLY) {
 576                 sb->s_flags |= MS_RDONLY;
 577
 578                 ret =  btrfs_commit_super(root);
 579                 WARN_ON(ret);
 580         } else {
 581                 if (root->fs_info->fs_devices->rw_devices == 0)
 582                         return -EACCES;
 583
 584                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 585                         return -EINVAL;
 586
 587                 /* recover relocation */
 588                 ret = btrfs_recover_relocation(root);
 589                 WARN_ON(ret);
 590
 591                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 592                 WARN_ON(ret);
 593
 594                 sb->s_flags &= ~MS_RDONLY;
 595         }
 596
 597         return 0;
 598 }
 599
 600 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 601 {
 602         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 603         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 604         int bits = dentry->d_sb->s_blocksize_bits;
 605         __be32 *fsid = (__be32 *)root->fs_info->fsid;
 606
 607         buf->f_namelen = BTRFS_NAME_LEN;
 608         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 609         buf->f_bfree = buf->f_blocks -
 610                 (btrfs_super_bytes_used(disk_super) >> bits);
 611         buf->f_bavail = buf->f_bfree;
 612         buf->f_bsize = dentry->d_sb->s_blocksize;
 613         buf->f_type = BTRFS_SUPER_MAGIC;
 614
 615         /* We treat it as constant endianness (it doesn't matter _which_)
 616            because we want the fsid to come out the same whether mounted
 617            on a big-endian or little-endian host */
 618         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
 619         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
 620         /* Mask in the root object ID too, to disambiguate subvols */
 621         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
 622         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
 623
 624         return 0;
 625 }
 626
 627 static struct file_system_type btrfs_fs_type = {
 628         .owner          = THIS_MODULE,
 629         .name           = "btrfs",
 630         .get_sb         = btrfs_get_sb,
 631         .kill_sb        = kill_anon_super,
 632         .fs_flags       = FS_REQUIRES_DEV,
 633 };
 634
 635 /*
 636  * used by btrfsctl to scan devices when no FS is mounted
 637  */
 638 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 639                                 unsigned long arg)
 640 {
 641         struct btrfs_ioctl_vol_args *vol;
 642         struct btrfs_fs_devices *fs_devices;
 643         int ret = -ENOTTY;
 644
 645         if (!capable(CAP_SYS_ADMIN))
 646                 return -EPERM;
 647
 648         vol = memdup_user((void __user *)arg, sizeof(*vol));
 649         if (IS_ERR(vol))
 650                 return PTR_ERR(vol);
 651
 652         switch (cmd) {
 653         case BTRFS_IOC_SCAN_DEV:
 654                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
 655                                             &btrfs_fs_type, &fs_devices);
 656                 break;
 657         }
 658
 659         kfree(vol);
 660         return ret;
 661 }
 662
 663 static int btrfs_freeze(struct super_block *sb)
 664 {
 665         struct btrfs_root *root = btrfs_sb(sb);
 666         mutex_lock(&root->fs_info->transaction_kthread_mutex);
 667         mutex_lock(&root->fs_info->cleaner_mutex);
 668         return 0;
 669 }
 670
 671 static int btrfs_unfreeze(struct super_block *sb)
 672 {
 673         struct btrfs_root *root = btrfs_sb(sb);
 674         mutex_unlock(&root->fs_info->cleaner_mutex);
 675         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 676         return 0;
 677 }
 678
 679 static struct super_operations btrfs_super_ops = {
 680         .delete_inode   = btrfs_delete_inode,
 681         .put_super      = btrfs_put_super,
 682         .sync_fs        = btrfs_sync_fs,
 683         .show_options   = btrfs_show_options,
 684         .write_inode    = btrfs_write_inode,
 685         .dirty_inode    = btrfs_dirty_inode,
 686         .alloc_inode    = btrfs_alloc_inode,
 687         .destroy_inode  = btrfs_destroy_inode,
 688         .statfs         = btrfs_statfs,
 689         .remount_fs     = btrfs_remount,
 690         .freeze_fs      = btrfs_freeze,
 691         .unfreeze_fs    = btrfs_unfreeze,
 692 };
 693
 694 static const struct file_operations btrfs_ctl_fops = {
 695         .unlocked_ioctl  = btrfs_control_ioctl,
 696         .compat_ioctl = btrfs_control_ioctl,
 697         .owner   = THIS_MODULE,
 698 };
 699
 700 static struct miscdevice btrfs_misc = {
 701         .minor          = MISC_DYNAMIC_MINOR,
 702         .name           = "btrfs-control",
 703         .fops           = &btrfs_ctl_fops
 704 };
 705
 706 static int btrfs_interface_init(void)
 707 {
 708         return misc_register(&btrfs_misc);
 709 }
 710
 711 static void btrfs_interface_exit(void)
 712 {
 713         if (misc_deregister(&btrfs_misc) < 0)
 714                 printk(KERN_INFO "misc_deregister failed for control device");
 715 }
 716
 717 static int __init init_btrfs_fs(void)
 718 {
 719         int err;
 720
 721         err = btrfs_init_sysfs();
 722         if (err)
 723                 return err;
 724
 725         err = btrfs_init_cachep();
 726         if (err)
 727                 goto free_sysfs;
 728
 729         err = extent_io_init();
 730         if (err)
 731                 goto free_cachep;
 732
 733         err = extent_map_init();
 734         if (err)
 735                 goto free_extent_io;
 736
 737         err = btrfs_interface_init();
 738         if (err)
 739                 goto free_extent_map;
 740
 741         err = register_filesystem(&btrfs_fs_type);
 742         if (err)
 743                 goto unregister_ioctl;
 744
 745         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 746         return 0;
 747
 748 unregister_ioctl:
 749         btrfs_interface_exit();
 750 free_extent_map:
 751         extent_map_exit();
 752 free_extent_io:
 753         extent_io_exit();
 754 free_cachep:
 755         btrfs_destroy_cachep();
 756 free_sysfs:
 757         btrfs_exit_sysfs();
 758         return err;
 759 }
 760
 761 static void __exit exit_btrfs_fs(void)
 762 {
 763         btrfs_destroy_cachep();
 764         extent_map_exit();
 765         extent_io_exit();
 766         btrfs_interface_exit();
 767         unregister_filesystem(&btrfs_fs_type);
 768         btrfs_exit_sysfs();
 769         btrfs_cleanup_fs_uuids();
 770         btrfs_zlib_exit();
 771 }
 772
 773 module_init(init_btrfs_fs)
 774 module_exit(exit_btrfs_fs)
 775
 776 MODULE_LICENSE("GPL");