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