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 <linux/slab.h>
  42 #include <linux/cleancache.h>
  43 #include <linux/mnt_namespace.h>
  44 #include <linux/ratelimit.h>
  45 #include "compat.h"
  46 #include "delayed-inode.h"
  47 #include "ctree.h"
  48 #include "disk-io.h"
  49 #include "transaction.h"
  50 #include "btrfs_inode.h"
  51 #include "ioctl.h"
  52 #include "print-tree.h"
  53 #include "xattr.h"
  54 #include "volumes.h"
  55 #include "version.h"
  56 #include "export.h"
  57 #include "compression.h"
  58
  59 #define CREATE_TRACE_POINTS
  60 #include <trace/events/btrfs.h>
  61
  62 static const struct super_operations btrfs_super_ops;
  63 static struct file_system_type btrfs_fs_type;
  64
  65 static const char *btrfs_decode_error(struct btrfs_fs_info *fs_info, int errno,
  66                                       char nbuf[16])
  67 {
  68         char *errstr = NULL;
  69
  70         switch (errno) {
  71         case -EIO:
  72                 errstr = "IO failure";
  73                 break;
  74         case -ENOMEM:
  75                 errstr = "Out of memory";
  76                 break;
  77         case -EROFS:
  78                 errstr = "Readonly filesystem";
  79                 break;
  80         default:
  81                 if (nbuf) {
  82                         if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
  83                                 errstr = nbuf;
  84                 }
  85                 break;
  86         }
  87
  88         return errstr;
  89 }
  90
  91 static void __save_error_info(struct btrfs_fs_info *fs_info)
  92 {
  93         /*
  94          * today we only save the error info into ram.  Long term we'll
  95          * also send it down to the disk
  96          */
  97         fs_info->fs_state = BTRFS_SUPER_FLAG_ERROR;
  98 }
  99
 100 /* NOTE:
 101  *      We move write_super stuff at umount in order to avoid deadlock
 102  *      for umount hold all lock.
 103  */
 104 static void save_error_info(struct btrfs_fs_info *fs_info)
 105 {
 106         __save_error_info(fs_info);
 107 }
 108
 109 /* btrfs handle error by forcing the filesystem readonly */
 110 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
 111 {
 112         struct super_block *sb = fs_info->sb;
 113
 114         if (sb->s_flags & MS_RDONLY)
 115                 return;
 116
 117         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 118                 sb->s_flags |= MS_RDONLY;
 119                 printk(KERN_INFO "btrfs is forced readonly\n");
 120         }
 121 }
 122
 123 /*
 124  * __btrfs_std_error decodes expected errors from the caller and
 125  * invokes the approciate error response.
 126  */
 127 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
 128                      unsigned int line, int errno)
 129 {
 130         struct super_block *sb = fs_info->sb;
 131         char nbuf[16];
 132         const char *errstr;
 133
 134         /*
 135          * Special case: if the error is EROFS, and we're already
 136          * under MS_RDONLY, then it is safe here.
 137          */
 138         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 139                 return;
 140
 141         errstr = btrfs_decode_error(fs_info, errno, nbuf);
 142         printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: %s\n",
 143                 sb->s_id, function, line, errstr);
 144         save_error_info(fs_info);
 145
 146         btrfs_handle_error(fs_info);
 147 }
 148
 149 static void btrfs_put_super(struct super_block *sb)
 150 {
 151         struct btrfs_root *root = btrfs_sb(sb);
 152         int ret;
 153
 154         ret = close_ctree(root);
 155         sb->s_fs_info = NULL;
 156
 157         (void)ret; /* FIXME: need to fix VFS to return error? */
 158 }
 159
 160 enum {
 161         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 162         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 163         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 164         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 165         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 166         Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
 167         Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
 168         Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
 169         Opt_check_integrity, Opt_check_integrity_including_extent_data,
 170         Opt_check_integrity_print_mask,
 171         Opt_err,
 172 };
 173
 174 static match_table_t tokens = {
 175         {Opt_degraded, "degraded"},
 176         {Opt_subvol, "subvol=%s"},
 177         {Opt_subvolid, "subvolid=%d"},
 178         {Opt_device, "device=%s"},
 179         {Opt_nodatasum, "nodatasum"},
 180         {Opt_nodatacow, "nodatacow"},
 181         {Opt_nobarrier, "nobarrier"},
 182         {Opt_max_inline, "max_inline=%s"},
 183         {Opt_alloc_start, "alloc_start=%s"},
 184         {Opt_thread_pool, "thread_pool=%d"},
 185         {Opt_compress, "compress"},
 186         {Opt_compress_type, "compress=%s"},
 187         {Opt_compress_force, "compress-force"},
 188         {Opt_compress_force_type, "compress-force=%s"},
 189         {Opt_ssd, "ssd"},
 190         {Opt_ssd_spread, "ssd_spread"},
 191         {Opt_nossd, "nossd"},
 192         {Opt_noacl, "noacl"},
 193         {Opt_notreelog, "notreelog"},
 194         {Opt_flushoncommit, "flushoncommit"},
 195         {Opt_ratio, "metadata_ratio=%d"},
 196         {Opt_discard, "discard"},
 197         {Opt_space_cache, "space_cache"},
 198         {Opt_clear_cache, "clear_cache"},
 199         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 200         {Opt_enospc_debug, "enospc_debug"},
 201         {Opt_subvolrootid, "subvolrootid=%d"},
 202         {Opt_defrag, "autodefrag"},
 203         {Opt_inode_cache, "inode_cache"},
 204         {Opt_no_space_cache, "nospace_cache"},
 205         {Opt_recovery, "recovery"},
 206         {Opt_skip_balance, "skip_balance"},
 207         {Opt_check_integrity, "check_int"},
 208         {Opt_check_integrity_including_extent_data, "check_int_data"},
 209         {Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
 210         {Opt_err, NULL},
 211 };
 212
 213 /*
 214  * Regular mount options parser.  Everything that is needed only when
 215  * reading in a new superblock is parsed here.
 216  */
 217 int btrfs_parse_options(struct btrfs_root *root, char *options)
 218 {
 219         struct btrfs_fs_info *info = root->fs_info;
 220         substring_t args[MAX_OPT_ARGS];
 221         char *p, *num, *orig = NULL;
 222         u64 cache_gen;
 223         int intarg;
 224         int ret = 0;
 225         char *compress_type;
 226         bool compress_force = false;
 227
 228         cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
 229         if (cache_gen)
 230                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 231
 232         if (!options)
 233                 goto out;
 234
 235         /*
 236          * strsep changes the string, duplicate it because parse_options
 237          * gets called twice
 238          */
 239         options = kstrdup(options, GFP_NOFS);
 240         if (!options)
 241                 return -ENOMEM;
 242
 243         orig = options;
 244
 245         while ((p = strsep(&options, ",")) != NULL) {
 246                 int token;
 247                 if (!*p)
 248                         continue;
 249
 250                 token = match_token(p, tokens, args);
 251                 switch (token) {
 252                 case Opt_degraded:
 253                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 254                         btrfs_set_opt(info->mount_opt, DEGRADED);
 255                         break;
 256                 case Opt_subvol:
 257                 case Opt_subvolid:
 258                 case Opt_subvolrootid:
 259                 case Opt_device:
 260                         /*
 261                          * These are parsed by btrfs_parse_early_options
 262                          * and can be happily ignored here.
 263                          */
 264                         break;
 265                 case Opt_nodatasum:
 266                         printk(KERN_INFO "btrfs: setting nodatasum\n");
 267                         btrfs_set_opt(info->mount_opt, NODATASUM);
 268                         break;
 269                 case Opt_nodatacow:
 270                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 271                         btrfs_set_opt(info->mount_opt, NODATACOW);
 272                         btrfs_set_opt(info->mount_opt, NODATASUM);
 273                         break;
 274                 case Opt_compress_force:
 275                 case Opt_compress_force_type:
 276                         compress_force = true;
 277                 case Opt_compress:
 278                 case Opt_compress_type:
 279                         if (token == Opt_compress ||
 280                             token == Opt_compress_force ||
 281                             strcmp(args[0].from, "zlib") == 0) {
 282                                 compress_type = "zlib";
 283                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 284                         } else if (strcmp(args[0].from, "lzo") == 0) {
 285                                 compress_type = "lzo";
 286                                 info->compress_type = BTRFS_COMPRESS_LZO;
 287                         } else {
 288                                 ret = -EINVAL;
 289                                 goto out;
 290                         }
 291
 292                         btrfs_set_opt(info->mount_opt, COMPRESS);
 293                         if (compress_force) {
 294                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 295                                 pr_info("btrfs: force %s compression\n",
 296                                         compress_type);
 297                         } else
 298                                 pr_info("btrfs: use %s compression\n",
 299                                         compress_type);
 300                         break;
 301                 case Opt_ssd:
 302                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 303                         btrfs_set_opt(info->mount_opt, SSD);
 304                         break;
 305                 case Opt_ssd_spread:
 306                         printk(KERN_INFO "btrfs: use spread ssd "
 307                                "allocation scheme\n");
 308                         btrfs_set_opt(info->mount_opt, SSD);
 309                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 310                         break;
 311                 case Opt_nossd:
 312                         printk(KERN_INFO "btrfs: not using ssd allocation "
 313                                "scheme\n");
 314                         btrfs_set_opt(info->mount_opt, NOSSD);
 315                         btrfs_clear_opt(info->mount_opt, SSD);
 316                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 317                         break;
 318                 case Opt_nobarrier:
 319                         printk(KERN_INFO "btrfs: turning off barriers\n");
 320                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 321                         break;
 322                 case Opt_thread_pool:
 323                         intarg = 0;
 324                         match_int(&args[0], &intarg);
 325                         if (intarg) {
 326                                 info->thread_pool_size = intarg;
 327                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 328                                        info->thread_pool_size);
 329                         }
 330                         break;
 331                 case Opt_max_inline:
 332                         num = match_strdup(&args[0]);
 333                         if (num) {
 334                                 info->max_inline = memparse(num, NULL);
 335                                 kfree(num);
 336
 337                                 if (info->max_inline) {
 338                                         info->max_inline = max_t(u64,
 339                                                 info->max_inline,
 340                                                 root->sectorsize);
 341                                 }
 342                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 343                                         (unsigned long long)info->max_inline);
 344                         }
 345                         break;
 346                 case Opt_alloc_start:
 347                         num = match_strdup(&args[0]);
 348                         if (num) {
 349                                 info->alloc_start = memparse(num, NULL);
 350                                 kfree(num);
 351                                 printk(KERN_INFO
 352                                         "btrfs: allocations start at %llu\n",
 353                                         (unsigned long long)info->alloc_start);
 354                         }
 355                         break;
 356                 case Opt_noacl:
 357                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 358                         break;
 359                 case Opt_notreelog:
 360                         printk(KERN_INFO "btrfs: disabling tree log\n");
 361                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 362                         break;
 363                 case Opt_flushoncommit:
 364                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 365                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 366                         break;
 367                 case Opt_ratio:
 368                         intarg = 0;
 369                         match_int(&args[0], &intarg);
 370                         if (intarg) {
 371                                 info->metadata_ratio = intarg;
 372                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 373                                        info->metadata_ratio);
 374                         }
 375                         break;
 376                 case Opt_discard:
 377                         btrfs_set_opt(info->mount_opt, DISCARD);
 378                         break;
 379                 case Opt_space_cache:
 380                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 381                         break;
 382                 case Opt_no_space_cache:
 383                         printk(KERN_INFO "btrfs: disabling disk space caching\n");
 384                         btrfs_clear_opt(info->mount_opt, SPACE_CACHE);
 385                         break;
 386                 case Opt_inode_cache:
 387                         printk(KERN_INFO "btrfs: enabling inode map caching\n");
 388                         btrfs_set_opt(info->mount_opt, INODE_MAP_CACHE);
 389                         break;
 390                 case Opt_clear_cache:
 391                         printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 392                         btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
 393                         break;
 394                 case Opt_user_subvol_rm_allowed:
 395                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 396                         break;
 397                 case Opt_enospc_debug:
 398                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 399                         break;
 400                 case Opt_defrag:
 401                         printk(KERN_INFO "btrfs: enabling auto defrag");
 402                         btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
 403                         break;
 404                 case Opt_recovery:
 405                         printk(KERN_INFO "btrfs: enabling auto recovery");
 406                         btrfs_set_opt(info->mount_opt, RECOVERY);
 407                         break;
 408                 case Opt_skip_balance:
 409                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 410                         break;
 411 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 412                 case Opt_check_integrity_including_extent_data:
 413                         printk(KERN_INFO "btrfs: enabling check integrity"
 414                                " including extent data\n");
 415                         btrfs_set_opt(info->mount_opt,
 416                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 417                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 418                         break;
 419                 case Opt_check_integrity:
 420                         printk(KERN_INFO "btrfs: enabling check integrity\n");
 421                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 422                         break;
 423                 case Opt_check_integrity_print_mask:
 424                         intarg = 0;
 425                         match_int(&args[0], &intarg);
 426                         if (intarg) {
 427                                 info->check_integrity_print_mask = intarg;
 428                                 printk(KERN_INFO "btrfs:"
 429                                        " check_integrity_print_mask 0x%x\n",
 430                                        info->check_integrity_print_mask);
 431                         }
 432                         break;
 433 #else
 434                 case Opt_check_integrity_including_extent_data:
 435                 case Opt_check_integrity:
 436                 case Opt_check_integrity_print_mask:
 437                         printk(KERN_ERR "btrfs: support for check_integrity*"
 438                                " not compiled in!\n");
 439                         ret = -EINVAL;
 440                         goto out;
 441 #endif
 442                 case Opt_err:
 443                         printk(KERN_INFO "btrfs: unrecognized mount option "
 444                                "'%s'\n", p);
 445                         ret = -EINVAL;
 446                         goto out;
 447                 default:
 448                         break;
 449                 }
 450         }
 451 out:
 452         if (!ret && btrfs_test_opt(root, SPACE_CACHE))
 453                 printk(KERN_INFO "btrfs: disk space caching is enabled\n");
 454         kfree(orig);
 455         return ret;
 456 }
 457
 458 /*
 459  * Parse mount options that are required early in the mount process.
 460  *
 461  * All other options will be parsed on much later in the mount process and
 462  * only when we need to allocate a new super block.
 463  */
 464 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 465                 void *holder, char **subvol_name, u64 *subvol_objectid,
 466                 u64 *subvol_rootid, struct btrfs_fs_devices **fs_devices)
 467 {
 468         substring_t args[MAX_OPT_ARGS];
 469         char *device_name, *opts, *orig, *p;
 470         int error = 0;
 471         int intarg;
 472
 473         if (!options)
 474                 return 0;
 475
 476         /*
 477          * strsep changes the string, duplicate it because parse_options
 478          * gets called twice
 479          */
 480         opts = kstrdup(options, GFP_KERNEL);
 481         if (!opts)
 482                 return -ENOMEM;
 483         orig = opts;
 484
 485         while ((p = strsep(&opts, ",")) != NULL) {
 486                 int token;
 487                 if (!*p)
 488                         continue;
 489
 490                 token = match_token(p, tokens, args);
 491                 switch (token) {
 492                 case Opt_subvol:
 493                         kfree(*subvol_name);
 494                         *subvol_name = match_strdup(&args[0]);
 495                         break;
 496                 case Opt_subvolid:
 497                         intarg = 0;
 498                         error = match_int(&args[0], &intarg);
 499                         if (!error) {
 500                                 /* we want the original fs_tree */
 501                                 if (!intarg)
 502                                         *subvol_objectid =
 503                                                 BTRFS_FS_TREE_OBJECTID;
 504                                 else
 505                                         *subvol_objectid = intarg;
 506                         }
 507                         break;
 508                 case Opt_subvolrootid:
 509                         intarg = 0;
 510                         error = match_int(&args[0], &intarg);
 511                         if (!error) {
 512                                 /* we want the original fs_tree */
 513                                 if (!intarg)
 514                                         *subvol_rootid =
 515                                                 BTRFS_FS_TREE_OBJECTID;
 516                                 else
 517                                         *subvol_rootid = intarg;
 518                         }
 519                         break;
 520                 case Opt_device:
 521                         device_name = match_strdup(&args[0]);
 522                         if (!device_name) {
 523                                 error = -ENOMEM;
 524                                 goto out;
 525                         }
 526                         error = btrfs_scan_one_device(device_name,
 527                                         flags, holder, fs_devices);
 528                         kfree(device_name);
 529                         if (error)
 530                                 goto out;
 531                         break;
 532                 default:
 533                         break;
 534                 }
 535         }
 536
 537 out:
 538         kfree(orig);
 539         return error;
 540 }
 541
 542 static struct dentry *get_default_root(struct super_block *sb,
 543                                        u64 subvol_objectid)
 544 {
 545         struct btrfs_root *root = sb->s_fs_info;
 546         struct btrfs_root *new_root;
 547         struct btrfs_dir_item *di;
 548         struct btrfs_path *path;
 549         struct btrfs_key location;
 550         struct inode *inode;
 551         u64 dir_id;
 552         int new = 0;
 553
 554         /*
 555          * We have a specific subvol we want to mount, just setup location and
 556          * go look up the root.
 557          */
 558         if (subvol_objectid) {
 559                 location.objectid = subvol_objectid;
 560                 location.type = BTRFS_ROOT_ITEM_KEY;
 561                 location.offset = (u64)-1;
 562                 goto find_root;
 563         }
 564
 565         path = btrfs_alloc_path();
 566         if (!path)
 567                 return ERR_PTR(-ENOMEM);
 568         path->leave_spinning = 1;
 569
 570         /*
 571          * Find the "default" dir item which points to the root item that we
 572          * will mount by default if we haven't been given a specific subvolume
 573          * to mount.
 574          */
 575         dir_id = btrfs_super_root_dir(root->fs_info->super_copy);
 576         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 577         if (IS_ERR(di)) {
 578                 btrfs_free_path(path);
 579                 return ERR_CAST(di);
 580         }
 581         if (!di) {
 582                 /*
 583                  * Ok the default dir item isn't there.  This is weird since
 584                  * it's always been there, but don't freak out, just try and
 585                  * mount to root most subvolume.
 586                  */
 587                 btrfs_free_path(path);
 588                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
 589                 new_root = root->fs_info->fs_root;
 590                 goto setup_root;
 591         }
 592
 593         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 594         btrfs_free_path(path);
 595
 596 find_root:
 597         new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
 598         if (IS_ERR(new_root))
 599                 return ERR_CAST(new_root);
 600
 601         if (btrfs_root_refs(&new_root->root_item) == 0)
 602                 return ERR_PTR(-ENOENT);
 603
 604         dir_id = btrfs_root_dirid(&new_root->root_item);
 605 setup_root:
 606         location.objectid = dir_id;
 607         location.type = BTRFS_INODE_ITEM_KEY;
 608         location.offset = 0;
 609
 610         inode = btrfs_iget(sb, &location, new_root, &new);
 611         if (IS_ERR(inode))
 612                 return ERR_CAST(inode);
 613
 614         /*
 615          * If we're just mounting the root most subvol put the inode and return
 616          * a reference to the dentry.  We will have already gotten a reference
 617          * to the inode in btrfs_fill_super so we're good to go.
 618          */
 619         if (!new && sb->s_root->d_inode == inode) {
 620                 iput(inode);
 621                 return dget(sb->s_root);
 622         }
 623
 624         return d_obtain_alias(inode);
 625 }
 626
 627 static int btrfs_fill_super(struct super_block *sb,
 628                             struct btrfs_fs_devices *fs_devices,
 629                             void *data, int silent)
 630 {
 631         struct inode *inode;
 632         struct dentry *root_dentry;
 633         struct btrfs_root *tree_root;
 634         struct btrfs_key key;
 635         int err;
 636
 637         sb->s_maxbytes = MAX_LFS_FILESIZE;
 638         sb->s_magic = BTRFS_SUPER_MAGIC;
 639         sb->s_op = &btrfs_super_ops;
 640         sb->s_d_op = &btrfs_dentry_operations;
 641         sb->s_export_op = &btrfs_export_ops;
 642         sb->s_xattr = btrfs_xattr_handlers;
 643         sb->s_time_gran = 1;
 644 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 645         sb->s_flags |= MS_POSIXACL;
 646 #endif
 647
 648         tree_root = open_ctree(sb, fs_devices, (char *)data);
 649
 650         if (IS_ERR(tree_root)) {
 651                 printk("btrfs: open_ctree failed\n");
 652                 return PTR_ERR(tree_root);
 653         }
 654         sb->s_fs_info = tree_root;
 655
 656         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 657         key.type = BTRFS_INODE_ITEM_KEY;
 658         key.offset = 0;
 659         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);
 660         if (IS_ERR(inode)) {
 661                 err = PTR_ERR(inode);
 662                 goto fail_close;
 663         }
 664
 665         root_dentry = d_alloc_root(inode);
 666         if (!root_dentry) {
 667                 iput(inode);
 668                 err = -ENOMEM;
 669                 goto fail_close;
 670         }
 671
 672         sb->s_root = root_dentry;
 673
 674         save_mount_options(sb, data);
 675         cleancache_init_fs(sb);
 676         return 0;
 677
 678 fail_close:
 679         close_ctree(tree_root);
 680         return err;
 681 }
 682
 683 int btrfs_sync_fs(struct super_block *sb, int wait)
 684 {
 685         struct btrfs_trans_handle *trans;
 686         struct btrfs_root *root = btrfs_sb(sb);
 687         int ret;
 688
 689         trace_btrfs_sync_fs(wait);
 690
 691         if (!wait) {
 692                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 693                 return 0;
 694         }
 695
 696         btrfs_start_delalloc_inodes(root, 0);
 697         btrfs_wait_ordered_extents(root, 0, 0);
 698
 699         trans = btrfs_start_transaction(root, 0);
 700         if (IS_ERR(trans))
 701                 return PTR_ERR(trans);
 702         ret = btrfs_commit_transaction(trans, root);
 703         return ret;
 704 }
 705
 706 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 707 {
 708         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 709         struct btrfs_fs_info *info = root->fs_info;
 710         char *compress_type;
 711
 712         if (btrfs_test_opt(root, DEGRADED))
 713                 seq_puts(seq, ",degraded");
 714         if (btrfs_test_opt(root, NODATASUM))
 715                 seq_puts(seq, ",nodatasum");
 716         if (btrfs_test_opt(root, NODATACOW))
 717                 seq_puts(seq, ",nodatacow");
 718         if (btrfs_test_opt(root, NOBARRIER))
 719                 seq_puts(seq, ",nobarrier");
 720         if (info->max_inline != 8192 * 1024)
 721                 seq_printf(seq, ",max_inline=%llu",
 722                            (unsigned long long)info->max_inline);
 723         if (info->alloc_start != 0)
 724                 seq_printf(seq, ",alloc_start=%llu",
 725                            (unsigned long long)info->alloc_start);
 726         if (info->thread_pool_size !=  min_t(unsigned long,
 727                                              num_online_cpus() + 2, 8))
 728                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 729         if (btrfs_test_opt(root, COMPRESS)) {
 730                 if (info->compress_type == BTRFS_COMPRESS_ZLIB)
 731                         compress_type = "zlib";
 732                 else
 733                         compress_type = "lzo";
 734                 if (btrfs_test_opt(root, FORCE_COMPRESS))
 735                         seq_printf(seq, ",compress-force=%s", compress_type);
 736                 else
 737                         seq_printf(seq, ",compress=%s", compress_type);
 738         }
 739         if (btrfs_test_opt(root, NOSSD))
 740                 seq_puts(seq, ",nossd");
 741         if (btrfs_test_opt(root, SSD_SPREAD))
 742                 seq_puts(seq, ",ssd_spread");
 743         else if (btrfs_test_opt(root, SSD))
 744                 seq_puts(seq, ",ssd");
 745         if (btrfs_test_opt(root, NOTREELOG))
 746                 seq_puts(seq, ",notreelog");
 747         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 748                 seq_puts(seq, ",flushoncommit");
 749         if (btrfs_test_opt(root, DISCARD))
 750                 seq_puts(seq, ",discard");
 751         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 752                 seq_puts(seq, ",noacl");
 753         if (btrfs_test_opt(root, SPACE_CACHE))
 754                 seq_puts(seq, ",space_cache");
 755         else
 756                 seq_puts(seq, ",nospace_cache");
 757         if (btrfs_test_opt(root, CLEAR_CACHE))
 758                 seq_puts(seq, ",clear_cache");
 759         if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
 760                 seq_puts(seq, ",user_subvol_rm_allowed");
 761         if (btrfs_test_opt(root, ENOSPC_DEBUG))
 762                 seq_puts(seq, ",enospc_debug");
 763         if (btrfs_test_opt(root, AUTO_DEFRAG))
 764                 seq_puts(seq, ",autodefrag");
 765         if (btrfs_test_opt(root, INODE_MAP_CACHE))
 766                 seq_puts(seq, ",inode_cache");
 767         if (btrfs_test_opt(root, SKIP_BALANCE))
 768                 seq_puts(seq, ",skip_balance");
 769         return 0;
 770 }
 771
 772 static int btrfs_test_super(struct super_block *s, void *data)
 773 {
 774         struct btrfs_root *test_root = data;
 775         struct btrfs_root *root = btrfs_sb(s);
 776
 777         /*
 778          * If this super block is going away, return false as it
 779          * can't match as an existing super block.
 780          */
 781         if (!atomic_read(&s->s_active))
 782                 return 0;
 783         return root->fs_info->fs_devices == test_root->fs_info->fs_devices;
 784 }
 785
 786 static int btrfs_set_super(struct super_block *s, void *data)
 787 {
 788         s->s_fs_info = data;
 789
 790         return set_anon_super(s, data);
 791 }
 792
 793 /*
 794  * subvolumes are identified by ino 256
 795  */
 796 static inline int is_subvolume_inode(struct inode *inode)
 797 {
 798         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
 799                 return 1;
 800         return 0;
 801 }
 802
 803 /*
 804  * This will strip out the subvol=%s argument for an argument string and add
 805  * subvolid=0 to make sure we get the actual tree root for path walking to the
 806  * subvol we want.
 807  */
 808 static char *setup_root_args(char *args)
 809 {
 810         unsigned copied = 0;
 811         unsigned len = strlen(args) + 2;
 812         char *pos;
 813         char *ret;
 814
 815         /*
 816          * We need the same args as before, but minus
 817          *
 818          * subvol=a
 819          *
 820          * and add
 821          *
 822          * subvolid=0
 823          *
 824          * which is a difference of 2 characters, so we allocate strlen(args) +
 825          * 2 characters.
 826          */
 827         ret = kzalloc(len * sizeof(char), GFP_NOFS);
 828         if (!ret)
 829                 return NULL;
 830         pos = strstr(args, "subvol=");
 831
 832         /* This shouldn't happen, but just in case.. */
 833         if (!pos) {
 834                 kfree(ret);
 835                 return NULL;
 836         }
 837
 838         /*
 839          * The subvol=<> arg is not at the front of the string, copy everybody
 840          * up to that into ret.
 841          */
 842         if (pos != args) {
 843                 *pos = '\0';
 844                 strcpy(ret, args);
 845                 copied += strlen(args);
 846                 pos++;
 847         }
 848
 849         strncpy(ret + copied, "subvolid=0", len - copied);
 850
 851         /* Length of subvolid=0 */
 852         copied += 10;
 853
 854         /*
 855          * If there is no , after the subvol= option then we know there's no
 856          * other options and we can just return.
 857          */
 858         pos = strchr(pos, ',');
 859         if (!pos)
 860                 return ret;
 861
 862         /* Copy the rest of the arguments into our buffer */
 863         strncpy(ret + copied, pos, len - copied);
 864         copied += strlen(pos);
 865
 866         return ret;
 867 }
 868
 869 static struct dentry *mount_subvol(const char *subvol_name, int flags,
 870                                    const char *device_name, char *data)
 871 {
 872         struct dentry *root;
 873         struct vfsmount *mnt;
 874         char *newargs;
 875
 876         newargs = setup_root_args(data);
 877         if (!newargs)
 878                 return ERR_PTR(-ENOMEM);
 879         mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
 880                              newargs);
 881         kfree(newargs);
 882         if (IS_ERR(mnt))
 883                 return ERR_CAST(mnt);
 884
 885         root = mount_subtree(mnt, subvol_name);
 886
 887         if (!IS_ERR(root) && !is_subvolume_inode(root->d_inode)) {
 888                 struct super_block *s = root->d_sb;
 889                 dput(root);
 890                 root = ERR_PTR(-EINVAL);
 891                 deactivate_locked_super(s);
 892                 printk(KERN_ERR "btrfs: '%s' is not a valid subvolume\n",
 893                                 subvol_name);
 894         }
 895
 896         return root;
 897 }
 898
 899 /*
 900  * Find a superblock for the given device / mount point.
 901  *
 902  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 903  *        for multiple device setup.  Make sure to keep it in sync.
 904  */
 905 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 906                 const char *device_name, void *data)
 907 {
 908         struct block_device *bdev = NULL;
 909         struct super_block *s;
 910         struct dentry *root;
 911         struct btrfs_fs_devices *fs_devices = NULL;
 912         struct btrfs_fs_info *fs_info = NULL;
 913         fmode_t mode = FMODE_READ;
 914         char *subvol_name = NULL;
 915         u64 subvol_objectid = 0;
 916         u64 subvol_rootid = 0;
 917         int error = 0;
 918
 919         if (!(flags & MS_RDONLY))
 920                 mode |= FMODE_WRITE;
 921
 922         error = btrfs_parse_early_options(data, mode, fs_type,
 923                                           &subvol_name, &subvol_objectid,
 924                                           &subvol_rootid, &fs_devices);
 925         if (error) {
 926                 kfree(subvol_name);
 927                 return ERR_PTR(error);
 928         }
 929
 930         if (subvol_name) {
 931                 root = mount_subvol(subvol_name, flags, device_name, data);
 932                 kfree(subvol_name);
 933                 return root;
 934         }
 935
 936         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
 937         if (error)
 938                 return ERR_PTR(error);
 939
 940         /*
 941          * Setup a dummy root and fs_info for test/set super.  This is because
 942          * we don't actually fill this stuff out until open_ctree, but we need
 943          * it for searching for existing supers, so this lets us do that and
 944          * then open_ctree will properly initialize everything later.
 945          */
 946         fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
 947         if (!fs_info)
 948                 return ERR_PTR(-ENOMEM);
 949
 950         fs_info->tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
 951         if (!fs_info->tree_root) {
 952                 error = -ENOMEM;
 953                 goto error_fs_info;
 954         }
 955         fs_info->tree_root->fs_info = fs_info;
 956         fs_info->fs_devices = fs_devices;
 957
 958         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
 959         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
 960         if (!fs_info->super_copy || !fs_info->super_for_commit) {
 961                 error = -ENOMEM;
 962                 goto error_fs_info;
 963         }
 964
 965         error = btrfs_open_devices(fs_devices, mode, fs_type);
 966         if (error)
 967                 goto error_fs_info;
 968
 969         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 970                 error = -EACCES;
 971                 goto error_close_devices;
 972         }
 973
 974         bdev = fs_devices->latest_bdev;
 975         s = sget(fs_type, btrfs_test_super, btrfs_set_super,
 976                  fs_info->tree_root);
 977         if (IS_ERR(s)) {
 978                 error = PTR_ERR(s);
 979                 goto error_close_devices;
 980         }
 981
 982         if (s->s_root) {
 983                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 984                         deactivate_locked_super(s);
 985                         error = -EBUSY;
 986                         goto error_close_devices;
 987                 }
 988
 989                 btrfs_close_devices(fs_devices);
 990                 free_fs_info(fs_info);
 991         } else {
 992                 char b[BDEVNAME_SIZE];
 993
 994                 s->s_flags = flags | MS_NOSEC;
 995                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 996                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 997                 error = btrfs_fill_super(s, fs_devices, data,
 998                                          flags & MS_SILENT ? 1 : 0);
 999                 if (error) {
1000                         deactivate_locked_super(s);
1001                         return ERR_PTR(error);
1002                 }
1003
1004                 s->s_flags |= MS_ACTIVE;
1005         }
1006
1007         root = get_default_root(s, subvol_objectid);
1008         if (IS_ERR(root)) {
1009                 deactivate_locked_super(s);
1010                 return root;
1011         }
1012
1013         return root;
1014
1015 error_close_devices:
1016         btrfs_close_devices(fs_devices);
1017 error_fs_info:
1018         free_fs_info(fs_info);
1019         return ERR_PTR(error);
1020 }
1021
1022 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1023 {
1024         struct btrfs_root *root = btrfs_sb(sb);
1025         int ret;
1026
1027         ret = btrfs_parse_options(root, data);
1028         if (ret)
1029                 return -EINVAL;
1030
1031         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1032                 return 0;
1033
1034         if (*flags & MS_RDONLY) {
1035                 sb->s_flags |= MS_RDONLY;
1036
1037                 ret =  btrfs_commit_super(root);
1038                 WARN_ON(ret);
1039         } else {
1040                 if (root->fs_info->fs_devices->rw_devices == 0)
1041                         return -EACCES;
1042
1043                 if (btrfs_super_log_root(root->fs_info->super_copy) != 0)
1044                         return -EINVAL;
1045
1046                 ret = btrfs_cleanup_fs_roots(root->fs_info);
1047                 WARN_ON(ret);
1048
1049                 /* recover relocation */
1050                 ret = btrfs_recover_relocation(root);
1051                 WARN_ON(ret);
1052
1053                 sb->s_flags &= ~MS_RDONLY;
1054         }
1055
1056         return 0;
1057 }
1058
1059 /* Used to sort the devices by max_avail(descending sort) */
1060 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1061                                        const void *dev_info2)
1062 {
1063         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1064             ((struct btrfs_device_info *)dev_info2)->max_avail)
1065                 return -1;
1066         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1067                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1068                 return 1;
1069         else
1070         return 0;
1071 }
1072
1073 /*
1074  * sort the devices by max_avail, in which max free extent size of each device
1075  * is stored.(Descending Sort)
1076  */
1077 static inline void btrfs_descending_sort_devices(
1078                                         struct btrfs_device_info *devices,
1079                                         size_t nr_devices)
1080 {
1081         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1082              btrfs_cmp_device_free_bytes, NULL);
1083 }
1084
1085 /*
1086  * The helper to calc the free space on the devices that can be used to store
1087  * file data.
1088  */
1089 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
1090 {
1091         struct btrfs_fs_info *fs_info = root->fs_info;
1092         struct btrfs_device_info *devices_info;
1093         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1094         struct btrfs_device *device;
1095         u64 skip_space;
1096         u64 type;
1097         u64 avail_space;
1098         u64 used_space;
1099         u64 min_stripe_size;
1100         int min_stripes = 1, num_stripes = 1;
1101         int i = 0, nr_devices;
1102         int ret;
1103
1104         nr_devices = fs_info->fs_devices->open_devices;
1105         BUG_ON(!nr_devices);
1106
1107         devices_info = kmalloc(sizeof(*devices_info) * nr_devices,
1108                                GFP_NOFS);
1109         if (!devices_info)
1110                 return -ENOMEM;
1111
1112         /* calc min stripe number for data space alloction */
1113         type = btrfs_get_alloc_profile(root, 1);
1114         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1115                 min_stripes = 2;
1116                 num_stripes = nr_devices;
1117         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1118                 min_stripes = 2;
1119                 num_stripes = 2;
1120         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1121                 min_stripes = 4;
1122                 num_stripes = 4;
1123         }
1124
1125         if (type & BTRFS_BLOCK_GROUP_DUP)
1126                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1127         else
1128                 min_stripe_size = BTRFS_STRIPE_LEN;
1129
1130         list_for_each_entry(device, &fs_devices->devices, dev_list) {
1131                 if (!device->in_fs_metadata || !device->bdev)
1132                         continue;
1133
1134                 avail_space = device->total_bytes - device->bytes_used;
1135
1136                 /* align with stripe_len */
1137                 do_div(avail_space, BTRFS_STRIPE_LEN);
1138                 avail_space *= BTRFS_STRIPE_LEN;
1139
1140                 /*
1141                  * In order to avoid overwritting the superblock on the drive,
1142                  * btrfs starts at an offset of at least 1MB when doing chunk
1143                  * allocation.
1144                  */
1145                 skip_space = 1024 * 1024;
1146
1147                 /* user can set the offset in fs_info->alloc_start. */
1148                 if (fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1149                     device->total_bytes)
1150                         skip_space = max(fs_info->alloc_start, skip_space);
1151
1152                 /*
1153                  * btrfs can not use the free space in [0, skip_space - 1],
1154                  * we must subtract it from the total. In order to implement
1155                  * it, we account the used space in this range first.
1156                  */
1157                 ret = btrfs_account_dev_extents_size(device, 0, skip_space - 1,
1158                                                      &used_space);
1159                 if (ret) {
1160                         kfree(devices_info);
1161                         return ret;
1162                 }
1163
1164                 /* calc the free space in [0, skip_space - 1] */
1165                 skip_space -= used_space;
1166
1167                 /*
1168                  * we can use the free space in [0, skip_space - 1], subtract
1169                  * it from the total.
1170                  */
1171                 if (avail_space && avail_space >= skip_space)
1172                         avail_space -= skip_space;
1173                 else
1174                         avail_space = 0;
1175
1176                 if (avail_space < min_stripe_size)
1177                         continue;
1178
1179                 devices_info[i].dev = device;
1180                 devices_info[i].max_avail = avail_space;
1181
1182                 i++;
1183         }
1184
1185         nr_devices = i;
1186
1187         btrfs_descending_sort_devices(devices_info, nr_devices);
1188
1189         i = nr_devices - 1;
1190         avail_space = 0;
1191         while (nr_devices >= min_stripes) {
1192                 if (num_stripes > nr_devices)
1193                         num_stripes = nr_devices;
1194
1195                 if (devices_info[i].max_avail >= min_stripe_size) {
1196                         int j;
1197                         u64 alloc_size;
1198
1199                         avail_space += devices_info[i].max_avail * num_stripes;
1200                         alloc_size = devices_info[i].max_avail;
1201                         for (j = i + 1 - num_stripes; j <= i; j++)
1202                                 devices_info[j].max_avail -= alloc_size;
1203                 }
1204                 i--;
1205                 nr_devices--;
1206         }
1207
1208         kfree(devices_info);
1209         *free_bytes = avail_space;
1210         return 0;
1211 }
1212
1213 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1214 {
1215         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
1216         struct btrfs_super_block *disk_super = root->fs_info->super_copy;
1217         struct list_head *head = &root->fs_info->space_info;
1218         struct btrfs_space_info *found;
1219         u64 total_used = 0;
1220         u64 total_free_data = 0;
1221         int bits = dentry->d_sb->s_blocksize_bits;
1222         __be32 *fsid = (__be32 *)root->fs_info->fsid;
1223         int ret;
1224
1225         /* holding chunk_muext to avoid allocating new chunks */
1226         mutex_lock(&root->fs_info->chunk_mutex);
1227         rcu_read_lock();
1228         list_for_each_entry_rcu(found, head, list) {
1229                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
1230                         total_free_data += found->disk_total - found->disk_used;
1231                         total_free_data -=
1232                                 btrfs_account_ro_block_groups_free_space(found);
1233                 }
1234
1235                 total_used += found->disk_used;
1236         }
1237         rcu_read_unlock();
1238
1239         buf->f_namelen = BTRFS_NAME_LEN;
1240         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
1241         buf->f_bfree = buf->f_blocks - (total_used >> bits);
1242         buf->f_bsize = dentry->d_sb->s_blocksize;
1243         buf->f_type = BTRFS_SUPER_MAGIC;
1244         buf->f_bavail = total_free_data;
1245         ret = btrfs_calc_avail_data_space(root, &total_free_data);
1246         if (ret) {
1247                 mutex_unlock(&root->fs_info->chunk_mutex);
1248                 return ret;
1249         }
1250         buf->f_bavail += total_free_data;
1251         buf->f_bavail = buf->f_bavail >> bits;
1252         mutex_unlock(&root->fs_info->chunk_mutex);
1253
1254         /* We treat it as constant endianness (it doesn't matter _which_)
1255            because we want the fsid to come out the same whether mounted
1256            on a big-endian or little-endian host */
1257         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
1258         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
1259         /* Mask in the root object ID too, to disambiguate subvols */
1260         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
1261         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
1262
1263         return 0;
1264 }
1265
1266 static struct file_system_type btrfs_fs_type = {
1267         .owner          = THIS_MODULE,
1268         .name           = "btrfs",
1269         .mount          = btrfs_mount,
1270         .kill_sb        = kill_anon_super,
1271         .fs_flags       = FS_REQUIRES_DEV,
1272 };
1273
1274 /*
1275  * used by btrfsctl to scan devices when no FS is mounted
1276  */
1277 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
1278                                 unsigned long arg)
1279 {
1280         struct btrfs_ioctl_vol_args *vol;
1281         struct btrfs_fs_devices *fs_devices;
1282         int ret = -ENOTTY;
1283
1284         if (!capable(CAP_SYS_ADMIN))
1285                 return -EPERM;
1286
1287         vol = memdup_user((void __user *)arg, sizeof(*vol));
1288         if (IS_ERR(vol))
1289                 return PTR_ERR(vol);
1290
1291         switch (cmd) {
1292         case BTRFS_IOC_SCAN_DEV:
1293                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1294                                             &btrfs_fs_type, &fs_devices);
1295                 break;
1296         }
1297
1298         kfree(vol);
1299         return ret;
1300 }
1301
1302 static int btrfs_freeze(struct super_block *sb)
1303 {
1304         struct btrfs_root *root = btrfs_sb(sb);
1305         mutex_lock(&root->fs_info->transaction_kthread_mutex);
1306         mutex_lock(&root->fs_info->cleaner_mutex);
1307         return 0;
1308 }
1309
1310 static int btrfs_unfreeze(struct super_block *sb)
1311 {
1312         struct btrfs_root *root = btrfs_sb(sb);
1313         mutex_unlock(&root->fs_info->cleaner_mutex);
1314         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
1315         return 0;
1316 }
1317
1318 static void btrfs_fs_dirty_inode(struct inode *inode, int flags)
1319 {
1320         int ret;
1321
1322         ret = btrfs_dirty_inode(inode);
1323         if (ret)
1324                 printk_ratelimited(KERN_ERR "btrfs: fail to dirty inode %Lu "
1325                                    "error %d\n", btrfs_ino(inode), ret);
1326 }
1327
1328 static const struct super_operations btrfs_super_ops = {
1329         .drop_inode     = btrfs_drop_inode,
1330         .evict_inode    = btrfs_evict_inode,
1331         .put_super      = btrfs_put_super,
1332         .sync_fs        = btrfs_sync_fs,
1333         .show_options   = btrfs_show_options,
1334         .write_inode    = btrfs_write_inode,
1335         .dirty_inode    = btrfs_fs_dirty_inode,
1336         .alloc_inode    = btrfs_alloc_inode,
1337         .destroy_inode  = btrfs_destroy_inode,
1338         .statfs         = btrfs_statfs,
1339         .remount_fs     = btrfs_remount,
1340         .freeze_fs      = btrfs_freeze,
1341         .unfreeze_fs    = btrfs_unfreeze,
1342 };
1343
1344 static const struct file_operations btrfs_ctl_fops = {
1345         .unlocked_ioctl  = btrfs_control_ioctl,
1346         .compat_ioctl = btrfs_control_ioctl,
1347         .owner   = THIS_MODULE,
1348         .llseek = noop_llseek,
1349 };
1350
1351 static struct miscdevice btrfs_misc = {
1352         .minor          = BTRFS_MINOR,
1353         .name           = "btrfs-control",
1354         .fops           = &btrfs_ctl_fops
1355 };
1356
1357 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
1358 MODULE_ALIAS("devname:btrfs-control");
1359
1360 static int btrfs_interface_init(void)
1361 {
1362         return misc_register(&btrfs_misc);
1363 }
1364
1365 static void btrfs_interface_exit(void)
1366 {
1367         if (misc_deregister(&btrfs_misc) < 0)
1368                 printk(KERN_INFO "misc_deregister failed for control device");
1369 }
1370
1371 static int __init init_btrfs_fs(void)
1372 {
1373         int err;
1374
1375         err = btrfs_init_sysfs();
1376         if (err)
1377                 return err;
1378
1379         err = btrfs_init_compress();
1380         if (err)
1381                 goto free_sysfs;
1382
1383         err = btrfs_init_cachep();
1384         if (err)
1385                 goto free_compress;
1386
1387         err = extent_io_init();
1388         if (err)
1389                 goto free_cachep;
1390
1391         err = extent_map_init();
1392         if (err)
1393                 goto free_extent_io;
1394
1395         err = btrfs_delayed_inode_init();
1396         if (err)
1397                 goto free_extent_map;
1398
1399         err = btrfs_interface_init();
1400         if (err)
1401                 goto free_delayed_inode;
1402
1403         err = register_filesystem(&btrfs_fs_type);
1404         if (err)
1405                 goto unregister_ioctl;
1406
1407         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
1408         return 0;
1409
1410 unregister_ioctl:
1411         btrfs_interface_exit();
1412 free_delayed_inode:
1413         btrfs_delayed_inode_exit();
1414 free_extent_map:
1415         extent_map_exit();
1416 free_extent_io:
1417         extent_io_exit();
1418 free_cachep:
1419         btrfs_destroy_cachep();
1420 free_compress:
1421         btrfs_exit_compress();
1422 free_sysfs:
1423         btrfs_exit_sysfs();
1424         return err;
1425 }
1426
1427 static void __exit exit_btrfs_fs(void)
1428 {
1429         btrfs_destroy_cachep();
1430         btrfs_delayed_inode_exit();
1431         extent_map_exit();
1432         extent_io_exit();
1433         btrfs_interface_exit();
1434         unregister_filesystem(&btrfs_fs_type);
1435         btrfs_exit_sysfs();
1436         btrfs_cleanup_fs_uuids();
1437         btrfs_exit_compress();
1438 }
1439
1440 module_init(init_btrfs_fs)
1441 module_exit(exit_btrfs_fs)
1442
1443 MODULE_LICENSE("GPL");