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