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 (sb->s_flags & MS_RDONLY)
 398                 return 0;
 399
 400         sb->s_dirt = 0;
 401         if (!wait) {
 402                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 403                 return 0;
 404         }
 405
 406         btrfs_start_delalloc_inodes(root);
 407         btrfs_wait_ordered_extents(root, 0);
 408
 409         trans = btrfs_start_transaction(root, 1);
 410         ret = btrfs_commit_transaction(trans, root);
 411         sb->s_dirt = 0;
 412         return ret;
 413 }
 414
 415 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 416 {
 417         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 418         struct btrfs_fs_info *info = root->fs_info;
 419
 420         if (btrfs_test_opt(root, DEGRADED))
 421                 seq_puts(seq, ",degraded");
 422         if (btrfs_test_opt(root, NODATASUM))
 423                 seq_puts(seq, ",nodatasum");
 424         if (btrfs_test_opt(root, NODATACOW))
 425                 seq_puts(seq, ",nodatacow");
 426         if (btrfs_test_opt(root, NOBARRIER))
 427                 seq_puts(seq, ",nobarrier");
 428         if (info->max_extent != (u64)-1)
 429                 seq_printf(seq, ",max_extent=%llu",
 430                            (unsigned long long)info->max_extent);
 431         if (info->max_inline != 8192 * 1024)
 432                 seq_printf(seq, ",max_inline=%llu",
 433                            (unsigned long long)info->max_inline);
 434         if (info->alloc_start != 0)
 435                 seq_printf(seq, ",alloc_start=%llu",
 436                            (unsigned long long)info->alloc_start);
 437         if (info->thread_pool_size !=  min_t(unsigned long,
 438                                              num_online_cpus() + 2, 8))
 439                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 440         if (btrfs_test_opt(root, COMPRESS))
 441                 seq_puts(seq, ",compress");
 442         if (btrfs_test_opt(root, NOSSD))
 443                 seq_puts(seq, ",nossd");
 444         if (btrfs_test_opt(root, SSD_SPREAD))
 445                 seq_puts(seq, ",ssd_spread");
 446         else if (btrfs_test_opt(root, SSD))
 447                 seq_puts(seq, ",ssd");
 448         if (btrfs_test_opt(root, NOTREELOG))
 449                 seq_puts(seq, ",notreelog");
 450         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 451                 seq_puts(seq, ",flushoncommit");
 452         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 453                 seq_puts(seq, ",noacl");
 454         return 0;
 455 }
 456
 457 static void btrfs_write_super(struct super_block *sb)
 458 {
 459         sb->s_dirt = 0;
 460 }
 461
 462 static int btrfs_test_super(struct super_block *s, void *data)
 463 {
 464         struct btrfs_fs_devices *test_fs_devices = data;
 465         struct btrfs_root *root = btrfs_sb(s);
 466
 467         return root->fs_info->fs_devices == test_fs_devices;
 468 }
 469
 470 /*
 471  * Find a superblock for the given device / mount point.
 472  *
 473  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 474  *        for multiple device setup.  Make sure to keep it in sync.
 475  */
 476 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 477                 const char *dev_name, void *data, struct vfsmount *mnt)
 478 {
 479         char *subvol_name = NULL;
 480         struct block_device *bdev = NULL;
 481         struct super_block *s;
 482         struct dentry *root;
 483         struct btrfs_fs_devices *fs_devices = NULL;
 484         fmode_t mode = FMODE_READ;
 485         int error = 0;
 486
 487         if (!(flags & MS_RDONLY))
 488                 mode |= FMODE_WRITE;
 489
 490         error = btrfs_parse_early_options(data, mode, fs_type,
 491                                           &subvol_name, &fs_devices);
 492         if (error)
 493                 return error;
 494
 495         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
 496         if (error)
 497                 goto error_free_subvol_name;
 498
 499         error = btrfs_open_devices(fs_devices, mode, fs_type);
 500         if (error)
 501                 goto error_free_subvol_name;
 502
 503         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 504                 error = -EACCES;
 505                 goto error_close_devices;
 506         }
 507
 508         bdev = fs_devices->latest_bdev;
 509         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
 510         if (IS_ERR(s))
 511                 goto error_s;
 512
 513         if (s->s_root) {
 514                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 515                         deactivate_locked_super(s);
 516                         error = -EBUSY;
 517                         goto error_close_devices;
 518                 }
 519
 520                 btrfs_close_devices(fs_devices);
 521         } else {
 522                 char b[BDEVNAME_SIZE];
 523
 524                 s->s_flags = flags;
 525                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 526                 error = btrfs_fill_super(s, fs_devices, data,
 527                                          flags & MS_SILENT ? 1 : 0);
 528                 if (error) {
 529                         deactivate_locked_super(s);
 530                         goto error_free_subvol_name;
 531                 }
 532
 533                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 534                 s->s_flags |= MS_ACTIVE;
 535         }
 536
 537         if (!strcmp(subvol_name, "."))
 538                 root = dget(s->s_root);
 539         else {
 540                 mutex_lock(&s->s_root->d_inode->i_mutex);
 541                 root = lookup_one_len(subvol_name, s->s_root,
 542                                       strlen(subvol_name));
 543                 mutex_unlock(&s->s_root->d_inode->i_mutex);
 544
 545                 if (IS_ERR(root)) {
 546                         deactivate_locked_super(s);
 547                         error = PTR_ERR(root);
 548                         goto error_free_subvol_name;
 549                 }
 550                 if (!root->d_inode) {
 551                         dput(root);
 552                         deactivate_locked_super(s);
 553                         error = -ENXIO;
 554                         goto error_free_subvol_name;
 555                 }
 556         }
 557
 558         mnt->mnt_sb = s;
 559         mnt->mnt_root = root;
 560
 561         kfree(subvol_name);
 562         return 0;
 563
 564 error_s:
 565         error = PTR_ERR(s);
 566 error_close_devices:
 567         btrfs_close_devices(fs_devices);
 568 error_free_subvol_name:
 569         kfree(subvol_name);
 570         return error;
 571 }
 572
 573 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 574 {
 575         struct btrfs_root *root = btrfs_sb(sb);
 576         int ret;
 577
 578         ret = btrfs_parse_options(root, data);
 579         if (ret)
 580                 return -EINVAL;
 581
 582         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 583                 return 0;
 584
 585         if (*flags & MS_RDONLY) {
 586                 sb->s_flags |= MS_RDONLY;
 587
 588                 ret =  btrfs_commit_super(root);
 589                 WARN_ON(ret);
 590         } else {
 591                 if (root->fs_info->fs_devices->rw_devices == 0)
 592                         return -EACCES;
 593
 594                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 595                         return -EINVAL;
 596
 597                 /* recover relocation */
 598                 ret = btrfs_recover_relocation(root);
 599                 WARN_ON(ret);
 600
 601                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 602                 WARN_ON(ret);
 603
 604                 sb->s_flags &= ~MS_RDONLY;
 605         }
 606
 607         return 0;
 608 }
 609
 610 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 611 {
 612         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 613         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 614         int bits = dentry->d_sb->s_blocksize_bits;
 615         __be32 *fsid = (__be32 *)root->fs_info->fsid;
 616
 617         buf->f_namelen = BTRFS_NAME_LEN;
 618         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 619         buf->f_bfree = buf->f_blocks -
 620                 (btrfs_super_bytes_used(disk_super) >> bits);
 621         buf->f_bavail = buf->f_bfree;
 622         buf->f_bsize = dentry->d_sb->s_blocksize;
 623         buf->f_type = BTRFS_SUPER_MAGIC;
 624
 625         /* We treat it as constant endianness (it doesn't matter _which_)
 626            because we want the fsid to come out the same whether mounted
 627            on a big-endian or little-endian host */
 628         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
 629         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
 630         /* Mask in the root object ID too, to disambiguate subvols */
 631         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
 632         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
 633
 634         return 0;
 635 }
 636
 637 static struct file_system_type btrfs_fs_type = {
 638         .owner          = THIS_MODULE,
 639         .name           = "btrfs",
 640         .get_sb         = btrfs_get_sb,
 641         .kill_sb        = kill_anon_super,
 642         .fs_flags       = FS_REQUIRES_DEV,
 643 };
 644
 645 /*
 646  * used by btrfsctl to scan devices when no FS is mounted
 647  */
 648 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 649                                 unsigned long arg)
 650 {
 651         struct btrfs_ioctl_vol_args *vol;
 652         struct btrfs_fs_devices *fs_devices;
 653         int ret = -ENOTTY;
 654
 655         if (!capable(CAP_SYS_ADMIN))
 656                 return -EPERM;
 657
 658         vol = memdup_user((void __user *)arg, sizeof(*vol));
 659         if (IS_ERR(vol))
 660                 return PTR_ERR(vol);
 661
 662         switch (cmd) {
 663         case BTRFS_IOC_SCAN_DEV:
 664                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
 665                                             &btrfs_fs_type, &fs_devices);
 666                 break;
 667         }
 668
 669         kfree(vol);
 670         return ret;
 671 }
 672
 673 static int btrfs_freeze(struct super_block *sb)
 674 {
 675         struct btrfs_root *root = btrfs_sb(sb);
 676         mutex_lock(&root->fs_info->transaction_kthread_mutex);
 677         mutex_lock(&root->fs_info->cleaner_mutex);
 678         return 0;
 679 }
 680
 681 static int btrfs_unfreeze(struct super_block *sb)
 682 {
 683         struct btrfs_root *root = btrfs_sb(sb);
 684         mutex_unlock(&root->fs_info->cleaner_mutex);
 685         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 686         return 0;
 687 }
 688
 689 static struct super_operations btrfs_super_ops = {
 690         .delete_inode   = btrfs_delete_inode,
 691         .put_super      = btrfs_put_super,
 692         .write_super    = btrfs_write_super,
 693         .sync_fs        = btrfs_sync_fs,
 694         .show_options   = btrfs_show_options,
 695         .write_inode    = btrfs_write_inode,
 696         .dirty_inode    = btrfs_dirty_inode,
 697         .alloc_inode    = btrfs_alloc_inode,
 698         .destroy_inode  = btrfs_destroy_inode,
 699         .statfs         = btrfs_statfs,
 700         .remount_fs     = btrfs_remount,
 701         .freeze_fs      = btrfs_freeze,
 702         .unfreeze_fs    = btrfs_unfreeze,
 703 };
 704
 705 static const struct file_operations btrfs_ctl_fops = {
 706         .unlocked_ioctl  = btrfs_control_ioctl,
 707         .compat_ioctl = btrfs_control_ioctl,
 708         .owner   = THIS_MODULE,
 709 };
 710
 711 static struct miscdevice btrfs_misc = {
 712         .minor          = MISC_DYNAMIC_MINOR,
 713         .name           = "btrfs-control",
 714         .fops           = &btrfs_ctl_fops
 715 };
 716
 717 static int btrfs_interface_init(void)
 718 {
 719         return misc_register(&btrfs_misc);
 720 }
 721
 722 static void btrfs_interface_exit(void)
 723 {
 724         if (misc_deregister(&btrfs_misc) < 0)
 725                 printk(KERN_INFO "misc_deregister failed for control device");
 726 }
 727
 728 static int __init init_btrfs_fs(void)
 729 {
 730         int err;
 731
 732         err = btrfs_init_sysfs();
 733         if (err)
 734                 return err;
 735
 736         err = btrfs_init_cachep();
 737         if (err)
 738                 goto free_sysfs;
 739
 740         err = extent_io_init();
 741         if (err)
 742                 goto free_cachep;
 743
 744         err = extent_map_init();
 745         if (err)
 746                 goto free_extent_io;
 747
 748         err = btrfs_interface_init();
 749         if (err)
 750                 goto free_extent_map;
 751
 752         err = register_filesystem(&btrfs_fs_type);
 753         if (err)
 754                 goto unregister_ioctl;
 755
 756         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 757         return 0;
 758
 759 unregister_ioctl:
 760         btrfs_interface_exit();
 761 free_extent_map:
 762         extent_map_exit();
 763 free_extent_io:
 764         extent_io_exit();
 765 free_cachep:
 766         btrfs_destroy_cachep();
 767 free_sysfs:
 768         btrfs_exit_sysfs();
 769         return err;
 770 }
 771
 772 static void __exit exit_btrfs_fs(void)
 773 {
 774         btrfs_destroy_cachep();
 775         extent_map_exit();
 776         extent_io_exit();
 777         btrfs_interface_exit();
 778         unregister_filesystem(&btrfs_fs_type);
 779         btrfs_exit_sysfs();
 780         btrfs_cleanup_fs_uuids();
 781         btrfs_zlib_exit();
 782 }
 783
 784 module_init(init_btrfs_fs)
 785 module_exit(exit_btrfs_fs)
 786
 787 MODULE_LICENSE("GPL");