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