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 "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 const 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_subvolid, Opt_device, Opt_nodatasum,
  68         Opt_nodatacow, Opt_max_extent, Opt_max_inline, Opt_alloc_start,
  69         Opt_nobarrier, Opt_ssd, Opt_nossd, Opt_ssd_spread, Opt_thread_pool,
  70         Opt_noacl, Opt_compress, Opt_compress_force, Opt_notreelog, Opt_ratio,
  71         Opt_flushoncommit,
  72         Opt_discard, Opt_err,
  73 };
  74
  75 static match_table_t tokens = {
  76         {Opt_degraded, "degraded"},
  77         {Opt_subvol, "subvol=%s"},
  78         {Opt_subvolid, "subvolid=%d"},
  79         {Opt_device, "device=%s"},
  80         {Opt_nodatasum, "nodatasum"},
  81         {Opt_nodatacow, "nodatacow"},
  82         {Opt_nobarrier, "nobarrier"},
  83         {Opt_max_extent, "max_extent=%s"},
  84         {Opt_max_inline, "max_inline=%s"},
  85         {Opt_alloc_start, "alloc_start=%s"},
  86         {Opt_thread_pool, "thread_pool=%d"},
  87         {Opt_compress, "compress"},
  88         {Opt_compress_force, "compress-force"},
  89         {Opt_ssd, "ssd"},
  90         {Opt_ssd_spread, "ssd_spread"},
  91         {Opt_nossd, "nossd"},
  92         {Opt_noacl, "noacl"},
  93         {Opt_notreelog, "notreelog"},
  94         {Opt_flushoncommit, "flushoncommit"},
  95         {Opt_ratio, "metadata_ratio=%d"},
  96         {Opt_discard, "discard"},
  97         {Opt_err, NULL},
  98 };
  99
 100 /*
 101  * Regular mount options parser.  Everything that is needed only when
 102  * reading in a new superblock is parsed here.
 103  */
 104 int btrfs_parse_options(struct btrfs_root *root, char *options)
 105 {
 106         struct btrfs_fs_info *info = root->fs_info;
 107         substring_t args[MAX_OPT_ARGS];
 108         char *p, *num, *orig;
 109         int intarg;
 110         int ret = 0;
 111
 112         if (!options)
 113                 return 0;
 114
 115         /*
 116          * strsep changes the string, duplicate it because parse_options
 117          * gets called twice
 118          */
 119         options = kstrdup(options, GFP_NOFS);
 120         if (!options)
 121                 return -ENOMEM;
 122
 123         orig = options;
 124
 125         while ((p = strsep(&options, ",")) != NULL) {
 126                 int token;
 127                 if (!*p)
 128                         continue;
 129
 130                 token = match_token(p, tokens, args);
 131                 switch (token) {
 132                 case Opt_degraded:
 133                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 134                         btrfs_set_opt(info->mount_opt, DEGRADED);
 135                         break;
 136                 case Opt_subvol:
 137                 case Opt_subvolid:
 138                 case Opt_device:
 139                         /*
 140                          * These are parsed by btrfs_parse_early_options
 141                          * and can be happily ignored here.
 142                          */
 143                         break;
 144                 case Opt_nodatasum:
 145                         printk(KERN_INFO "btrfs: setting nodatasum\n");
 146                         btrfs_set_opt(info->mount_opt, NODATASUM);
 147                         break;
 148                 case Opt_nodatacow:
 149                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 150                         btrfs_set_opt(info->mount_opt, NODATACOW);
 151                         btrfs_set_opt(info->mount_opt, NODATASUM);
 152                         break;
 153                 case Opt_compress:
 154                         printk(KERN_INFO "btrfs: use compression\n");
 155                         btrfs_set_opt(info->mount_opt, COMPRESS);
 156                         break;
 157                 case Opt_compress_force:
 158                         printk(KERN_INFO "btrfs: forcing compression\n");
 159                         btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 160                         btrfs_set_opt(info->mount_opt, COMPRESS);
 161                         break;
 162                 case Opt_ssd:
 163                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 164                         btrfs_set_opt(info->mount_opt, SSD);
 165                         break;
 166                 case Opt_ssd_spread:
 167                         printk(KERN_INFO "btrfs: use spread ssd "
 168                                "allocation scheme\n");
 169                         btrfs_set_opt(info->mount_opt, SSD);
 170                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 171                         break;
 172                 case Opt_nossd:
 173                         printk(KERN_INFO "btrfs: not using ssd allocation "
 174                                "scheme\n");
 175                         btrfs_set_opt(info->mount_opt, NOSSD);
 176                         btrfs_clear_opt(info->mount_opt, SSD);
 177                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 178                         break;
 179                 case Opt_nobarrier:
 180                         printk(KERN_INFO "btrfs: turning off barriers\n");
 181                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 182                         break;
 183                 case Opt_thread_pool:
 184                         intarg = 0;
 185                         match_int(&args[0], &intarg);
 186                         if (intarg) {
 187                                 info->thread_pool_size = intarg;
 188                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 189                                        info->thread_pool_size);
 190                         }
 191                         break;
 192                 case Opt_max_extent:
 193                         num = match_strdup(&args[0]);
 194                         if (num) {
 195                                 info->max_extent = memparse(num, NULL);
 196                                 kfree(num);
 197
 198                                 info->max_extent = max_t(u64,
 199                                         info->max_extent, root->sectorsize);
 200                                 printk(KERN_INFO "btrfs: max_extent at %llu\n",
 201                                        (unsigned long long)info->max_extent);
 202                         }
 203                         break;
 204                 case Opt_max_inline:
 205                         num = match_strdup(&args[0]);
 206                         if (num) {
 207                                 info->max_inline = memparse(num, NULL);
 208                                 kfree(num);
 209
 210                                 if (info->max_inline) {
 211                                         info->max_inline = max_t(u64,
 212                                                 info->max_inline,
 213                                                 root->sectorsize);
 214                                 }
 215                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 216                                         (unsigned long long)info->max_inline);
 217                         }
 218                         break;
 219                 case Opt_alloc_start:
 220                         num = match_strdup(&args[0]);
 221                         if (num) {
 222                                 info->alloc_start = memparse(num, NULL);
 223                                 kfree(num);
 224                                 printk(KERN_INFO
 225                                         "btrfs: allocations start at %llu\n",
 226                                         (unsigned long long)info->alloc_start);
 227                         }
 228                         break;
 229                 case Opt_noacl:
 230                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 231                         break;
 232                 case Opt_notreelog:
 233                         printk(KERN_INFO "btrfs: disabling tree log\n");
 234                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 235                         break;
 236                 case Opt_flushoncommit:
 237                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 238                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 239                         break;
 240                 case Opt_ratio:
 241                         intarg = 0;
 242                         match_int(&args[0], &intarg);
 243                         if (intarg) {
 244                                 info->metadata_ratio = intarg;
 245                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 246                                        info->metadata_ratio);
 247                         }
 248                         break;
 249                 case Opt_discard:
 250                         btrfs_set_opt(info->mount_opt, DISCARD);
 251                         break;
 252                 case Opt_err:
 253                         printk(KERN_INFO "btrfs: unrecognized mount option "
 254                                "'%s'\n", p);
 255                         ret = -EINVAL;
 256                         goto out;
 257                 default:
 258                         break;
 259                 }
 260         }
 261 out:
 262         kfree(orig);
 263         return ret;
 264 }
 265
 266 /*
 267  * Parse mount options that are required early in the mount process.
 268  *
 269  * All other options will be parsed on much later in the mount process and
 270  * only when we need to allocate a new super block.
 271  */
 272 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 273                 void *holder, char **subvol_name, u64 *subvol_objectid,
 274                 struct btrfs_fs_devices **fs_devices)
 275 {
 276         substring_t args[MAX_OPT_ARGS];
 277         char *opts, *p;
 278         int error = 0;
 279         int intarg;
 280
 281         if (!options)
 282                 goto out;
 283
 284         /*
 285          * strsep changes the string, duplicate it because parse_options
 286          * gets called twice
 287          */
 288         opts = kstrdup(options, GFP_KERNEL);
 289         if (!opts)
 290                 return -ENOMEM;
 291
 292         while ((p = strsep(&opts, ",")) != NULL) {
 293                 int token;
 294                 if (!*p)
 295                         continue;
 296
 297                 token = match_token(p, tokens, args);
 298                 switch (token) {
 299                 case Opt_subvol:
 300                         *subvol_name = match_strdup(&args[0]);
 301                         break;
 302                 case Opt_subvolid:
 303                         intarg = 0;
 304                         error = match_int(&args[0], &intarg);
 305                         if (!error) {
 306                                 /* we want the original fs_tree */
 307                                 if (!intarg)
 308                                         *subvol_objectid =
 309                                                 BTRFS_FS_TREE_OBJECTID;
 310                                 else
 311                                         *subvol_objectid = intarg;
 312                         }
 313                         break;
 314                 case Opt_device:
 315                         error = btrfs_scan_one_device(match_strdup(&args[0]),
 316                                         flags, holder, fs_devices);
 317                         if (error)
 318                                 goto out_free_opts;
 319                         break;
 320                 default:
 321                         break;
 322                 }
 323         }
 324
 325  out_free_opts:
 326         kfree(opts);
 327  out:
 328         /*
 329          * If no subvolume name is specified we use the default one.  Allocate
 330          * a copy of the string "." here so that code later in the
 331          * mount path doesn't care if it's the default volume or another one.
 332          */
 333         if (!*subvol_name) {
 334                 *subvol_name = kstrdup(".", GFP_KERNEL);
 335                 if (!*subvol_name)
 336                         return -ENOMEM;
 337         }
 338         return error;
 339 }
 340
 341 static struct dentry *get_default_root(struct super_block *sb,
 342                                        u64 subvol_objectid)
 343 {
 344         struct btrfs_root *root = sb->s_fs_info;
 345         struct btrfs_root *new_root;
 346         struct btrfs_dir_item *di;
 347         struct btrfs_path *path;
 348         struct btrfs_key location;
 349         struct inode *inode;
 350         struct dentry *dentry;
 351         u64 dir_id;
 352         int new = 0;
 353
 354         /*
 355          * We have a specific subvol we want to mount, just setup location and
 356          * go look up the root.
 357          */
 358         if (subvol_objectid) {
 359                 location.objectid = subvol_objectid;
 360                 location.type = BTRFS_ROOT_ITEM_KEY;
 361                 location.offset = (u64)-1;
 362                 goto find_root;
 363         }
 364
 365         path = btrfs_alloc_path();
 366         if (!path)
 367                 return ERR_PTR(-ENOMEM);
 368         path->leave_spinning = 1;
 369
 370         /*
 371          * Find the "default" dir item which points to the root item that we
 372          * will mount by default if we haven't been given a specific subvolume
 373          * to mount.
 374          */
 375         dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
 376         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 377         if (!di) {
 378                 /*
 379                  * Ok the default dir item isn't there.  This is weird since
 380                  * it's always been there, but don't freak out, just try and
 381                  * mount to root most subvolume.
 382                  */
 383                 btrfs_free_path(path);
 384                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
 385                 new_root = root->fs_info->fs_root;
 386                 goto setup_root;
 387         }
 388
 389         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 390         btrfs_free_path(path);
 391
 392 find_root:
 393         new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
 394         if (IS_ERR(new_root))
 395                 return ERR_PTR(PTR_ERR(new_root));
 396
 397         if (btrfs_root_refs(&new_root->root_item) == 0)
 398                 return ERR_PTR(-ENOENT);
 399
 400         dir_id = btrfs_root_dirid(&new_root->root_item);
 401 setup_root:
 402         location.objectid = dir_id;
 403         location.type = BTRFS_INODE_ITEM_KEY;
 404         location.offset = 0;
 405
 406         inode = btrfs_iget(sb, &location, new_root, &new);
 407         if (!inode)
 408                 return ERR_PTR(-ENOMEM);
 409
 410         /*
 411          * If we're just mounting the root most subvol put the inode and return
 412          * a reference to the dentry.  We will have already gotten a reference
 413          * to the inode in btrfs_fill_super so we're good to go.
 414          */
 415         if (!new && sb->s_root->d_inode == inode) {
 416                 iput(inode);
 417                 return dget(sb->s_root);
 418         }
 419
 420         if (new) {
 421                 const struct qstr name = { .name = "/", .len = 1 };
 422
 423                 /*
 424                  * New inode, we need to make the dentry a sibling of s_root so
 425                  * everything gets cleaned up properly on unmount.
 426                  */
 427                 dentry = d_alloc(sb->s_root, &name);
 428                 if (!dentry) {
 429                         iput(inode);
 430                         return ERR_PTR(-ENOMEM);
 431                 }
 432                 d_splice_alias(inode, dentry);
 433         } else {
 434                 /*
 435                  * We found the inode in cache, just find a dentry for it and
 436                  * put the reference to the inode we just got.
 437                  */
 438                 dentry = d_find_alias(inode);
 439                 iput(inode);
 440         }
 441
 442         return dentry;
 443 }
 444
 445 static int btrfs_fill_super(struct super_block *sb,
 446                             struct btrfs_fs_devices *fs_devices,
 447                             void *data, int silent)
 448 {
 449         struct inode *inode;
 450         struct dentry *root_dentry;
 451         struct btrfs_super_block *disk_super;
 452         struct btrfs_root *tree_root;
 453         struct btrfs_key key;
 454         int err;
 455
 456         sb->s_maxbytes = MAX_LFS_FILESIZE;
 457         sb->s_magic = BTRFS_SUPER_MAGIC;
 458         sb->s_op = &btrfs_super_ops;
 459         sb->s_export_op = &btrfs_export_ops;
 460         sb->s_xattr = btrfs_xattr_handlers;
 461         sb->s_time_gran = 1;
 462 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 463         sb->s_flags |= MS_POSIXACL;
 464 #endif
 465
 466         tree_root = open_ctree(sb, fs_devices, (char *)data);
 467
 468         if (IS_ERR(tree_root)) {
 469                 printk("btrfs: open_ctree failed\n");
 470                 return PTR_ERR(tree_root);
 471         }
 472         sb->s_fs_info = tree_root;
 473         disk_super = &tree_root->fs_info->super_copy;
 474
 475         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 476         key.type = BTRFS_INODE_ITEM_KEY;
 477         key.offset = 0;
 478         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);
 479         if (IS_ERR(inode)) {
 480                 err = PTR_ERR(inode);
 481                 goto fail_close;
 482         }
 483
 484         root_dentry = d_alloc_root(inode);
 485         if (!root_dentry) {
 486                 iput(inode);
 487                 err = -ENOMEM;
 488                 goto fail_close;
 489         }
 490
 491         sb->s_root = root_dentry;
 492
 493         save_mount_options(sb, data);
 494         return 0;
 495
 496 fail_close:
 497         close_ctree(tree_root);
 498         return err;
 499 }
 500
 501 int btrfs_sync_fs(struct super_block *sb, int wait)
 502 {
 503         struct btrfs_trans_handle *trans;
 504         struct btrfs_root *root = btrfs_sb(sb);
 505         int ret;
 506
 507         if (!wait) {
 508                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 509                 return 0;
 510         }
 511
 512         btrfs_start_delalloc_inodes(root, 0);
 513         btrfs_wait_ordered_extents(root, 0, 0);
 514
 515         trans = btrfs_start_transaction(root, 1);
 516         ret = btrfs_commit_transaction(trans, root);
 517         return ret;
 518 }
 519
 520 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 521 {
 522         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 523         struct btrfs_fs_info *info = root->fs_info;
 524
 525         if (btrfs_test_opt(root, DEGRADED))
 526                 seq_puts(seq, ",degraded");
 527         if (btrfs_test_opt(root, NODATASUM))
 528                 seq_puts(seq, ",nodatasum");
 529         if (btrfs_test_opt(root, NODATACOW))
 530                 seq_puts(seq, ",nodatacow");
 531         if (btrfs_test_opt(root, NOBARRIER))
 532                 seq_puts(seq, ",nobarrier");
 533         if (info->max_extent != (u64)-1)
 534                 seq_printf(seq, ",max_extent=%llu",
 535                            (unsigned long long)info->max_extent);
 536         if (info->max_inline != 8192 * 1024)
 537                 seq_printf(seq, ",max_inline=%llu",
 538                            (unsigned long long)info->max_inline);
 539         if (info->alloc_start != 0)
 540                 seq_printf(seq, ",alloc_start=%llu",
 541                            (unsigned long long)info->alloc_start);
 542         if (info->thread_pool_size !=  min_t(unsigned long,
 543                                              num_online_cpus() + 2, 8))
 544                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 545         if (btrfs_test_opt(root, COMPRESS))
 546                 seq_puts(seq, ",compress");
 547         if (btrfs_test_opt(root, NOSSD))
 548                 seq_puts(seq, ",nossd");
 549         if (btrfs_test_opt(root, SSD_SPREAD))
 550                 seq_puts(seq, ",ssd_spread");
 551         else if (btrfs_test_opt(root, SSD))
 552                 seq_puts(seq, ",ssd");
 553         if (btrfs_test_opt(root, NOTREELOG))
 554                 seq_puts(seq, ",notreelog");
 555         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 556                 seq_puts(seq, ",flushoncommit");
 557         if (btrfs_test_opt(root, DISCARD))
 558                 seq_puts(seq, ",discard");
 559         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 560                 seq_puts(seq, ",noacl");
 561         return 0;
 562 }
 563
 564 static int btrfs_test_super(struct super_block *s, void *data)
 565 {
 566         struct btrfs_fs_devices *test_fs_devices = data;
 567         struct btrfs_root *root = btrfs_sb(s);
 568
 569         return root->fs_info->fs_devices == test_fs_devices;
 570 }
 571
 572 /*
 573  * Find a superblock for the given device / mount point.
 574  *
 575  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 576  *        for multiple device setup.  Make sure to keep it in sync.
 577  */
 578 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 579                 const char *dev_name, void *data, struct vfsmount *mnt)
 580 {
 581         struct block_device *bdev = NULL;
 582         struct super_block *s;
 583         struct dentry *root;
 584         struct btrfs_fs_devices *fs_devices = NULL;
 585         fmode_t mode = FMODE_READ;
 586         char *subvol_name = NULL;
 587         u64 subvol_objectid = 0;
 588         int error = 0;
 589         int found = 0;
 590
 591         if (!(flags & MS_RDONLY))
 592                 mode |= FMODE_WRITE;
 593
 594         error = btrfs_parse_early_options(data, mode, fs_type,
 595                                           &subvol_name, &subvol_objectid,
 596                                           &fs_devices);
 597         if (error)
 598                 return error;
 599
 600         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
 601         if (error)
 602                 goto error_free_subvol_name;
 603
 604         error = btrfs_open_devices(fs_devices, mode, fs_type);
 605         if (error)
 606                 goto error_free_subvol_name;
 607
 608         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 609                 error = -EACCES;
 610                 goto error_close_devices;
 611         }
 612
 613         bdev = fs_devices->latest_bdev;
 614         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
 615         if (IS_ERR(s))
 616                 goto error_s;
 617
 618         if (s->s_root) {
 619                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 620                         deactivate_locked_super(s);
 621                         error = -EBUSY;
 622                         goto error_close_devices;
 623                 }
 624
 625                 found = 1;
 626                 btrfs_close_devices(fs_devices);
 627         } else {
 628                 char b[BDEVNAME_SIZE];
 629
 630                 s->s_flags = flags;
 631                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 632                 error = btrfs_fill_super(s, fs_devices, data,
 633                                          flags & MS_SILENT ? 1 : 0);
 634                 if (error) {
 635                         deactivate_locked_super(s);
 636                         goto error_free_subvol_name;
 637                 }
 638
 639                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 640                 s->s_flags |= MS_ACTIVE;
 641         }
 642
 643         root = get_default_root(s, subvol_objectid);
 644         if (IS_ERR(root)) {
 645                 error = PTR_ERR(root);
 646                 deactivate_locked_super(s);
 647                 goto error;
 648         }
 649         /* if they gave us a subvolume name bind mount into that */
 650         if (strcmp(subvol_name, ".")) {
 651                 struct dentry *new_root;
 652                 mutex_lock(&root->d_inode->i_mutex);
 653                 new_root = lookup_one_len(subvol_name, root,
 654                                       strlen(subvol_name));
 655                 mutex_unlock(&root->d_inode->i_mutex);
 656
 657                 if (IS_ERR(new_root)) {
 658                         deactivate_locked_super(s);
 659                         error = PTR_ERR(new_root);
 660                         dput(root);
 661                         goto error_close_devices;
 662                 }
 663                 if (!new_root->d_inode) {
 664                         dput(root);
 665                         dput(new_root);
 666                         deactivate_locked_super(s);
 667                         error = -ENXIO;
 668                         goto error_close_devices;
 669                 }
 670                 dput(root);
 671                 root = new_root;
 672         }
 673
 674         mnt->mnt_sb = s;
 675         mnt->mnt_root = root;
 676
 677         kfree(subvol_name);
 678         return 0;
 679
 680 error_s:
 681         error = PTR_ERR(s);
 682 error_close_devices:
 683         btrfs_close_devices(fs_devices);
 684 error_free_subvol_name:
 685         kfree(subvol_name);
 686 error:
 687         return error;
 688 }
 689
 690 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 691 {
 692         struct btrfs_root *root = btrfs_sb(sb);
 693         int ret;
 694
 695         ret = btrfs_parse_options(root, data);
 696         if (ret)
 697                 return -EINVAL;
 698
 699         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 700                 return 0;
 701
 702         if (*flags & MS_RDONLY) {
 703                 sb->s_flags |= MS_RDONLY;
 704
 705                 ret =  btrfs_commit_super(root);
 706                 WARN_ON(ret);
 707         } else {
 708                 if (root->fs_info->fs_devices->rw_devices == 0)
 709                         return -EACCES;
 710
 711                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 712                         return -EINVAL;
 713
 714                 /* recover relocation */
 715                 ret = btrfs_recover_relocation(root);
 716                 WARN_ON(ret);
 717
 718                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 719                 WARN_ON(ret);
 720
 721                 sb->s_flags &= ~MS_RDONLY;
 722         }
 723
 724         return 0;
 725 }
 726
 727 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 728 {
 729         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 730         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 731         struct list_head *head = &root->fs_info->space_info;
 732         struct btrfs_space_info *found;
 733         u64 total_used = 0;
 734         u64 data_used = 0;
 735         int bits = dentry->d_sb->s_blocksize_bits;
 736         __be32 *fsid = (__be32 *)root->fs_info->fsid;
 737
 738         rcu_read_lock();
 739         list_for_each_entry_rcu(found, head, list) {
 740                 if (found->flags & (BTRFS_BLOCK_GROUP_DUP|
 741                                     BTRFS_BLOCK_GROUP_RAID10|
 742                                     BTRFS_BLOCK_GROUP_RAID1)) {
 743                         total_used += found->bytes_used;
 744                         if (found->flags & BTRFS_BLOCK_GROUP_DATA)
 745                                 data_used += found->bytes_used;
 746                         else
 747                                 data_used += found->total_bytes;
 748                 }
 749
 750                 total_used += found->bytes_used;
 751                 if (found->flags & BTRFS_BLOCK_GROUP_DATA)
 752                         data_used += found->bytes_used;
 753                 else
 754                         data_used += found->total_bytes;
 755         }
 756         rcu_read_unlock();
 757
 758         buf->f_namelen = BTRFS_NAME_LEN;
 759         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 760         buf->f_bfree = buf->f_blocks - (total_used >> bits);
 761         buf->f_bavail = buf->f_blocks - (data_used >> bits);
 762         buf->f_bsize = dentry->d_sb->s_blocksize;
 763         buf->f_type = BTRFS_SUPER_MAGIC;
 764
 765         /* We treat it as constant endianness (it doesn't matter _which_)
 766            because we want the fsid to come out the same whether mounted
 767            on a big-endian or little-endian host */
 768         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
 769         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
 770         /* Mask in the root object ID too, to disambiguate subvols */
 771         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
 772         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
 773
 774         return 0;
 775 }
 776
 777 static struct file_system_type btrfs_fs_type = {
 778         .owner          = THIS_MODULE,
 779         .name           = "btrfs",
 780         .get_sb         = btrfs_get_sb,
 781         .kill_sb        = kill_anon_super,
 782         .fs_flags       = FS_REQUIRES_DEV,
 783 };
 784
 785 /*
 786  * used by btrfsctl to scan devices when no FS is mounted
 787  */
 788 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 789                                 unsigned long arg)
 790 {
 791         struct btrfs_ioctl_vol_args *vol;
 792         struct btrfs_fs_devices *fs_devices;
 793         int ret = -ENOTTY;
 794
 795         if (!capable(CAP_SYS_ADMIN))
 796                 return -EPERM;
 797
 798         vol = memdup_user((void __user *)arg, sizeof(*vol));
 799         if (IS_ERR(vol))
 800                 return PTR_ERR(vol);
 801
 802         switch (cmd) {
 803         case BTRFS_IOC_SCAN_DEV:
 804                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
 805                                             &btrfs_fs_type, &fs_devices);
 806                 break;
 807         }
 808
 809         kfree(vol);
 810         return ret;
 811 }
 812
 813 static int btrfs_freeze(struct super_block *sb)
 814 {
 815         struct btrfs_root *root = btrfs_sb(sb);
 816         mutex_lock(&root->fs_info->transaction_kthread_mutex);
 817         mutex_lock(&root->fs_info->cleaner_mutex);
 818         return 0;
 819 }
 820
 821 static int btrfs_unfreeze(struct super_block *sb)
 822 {
 823         struct btrfs_root *root = btrfs_sb(sb);
 824         mutex_unlock(&root->fs_info->cleaner_mutex);
 825         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 826         return 0;
 827 }
 828
 829 static const struct super_operations btrfs_super_ops = {
 830         .drop_inode     = btrfs_drop_inode,
 831         .delete_inode   = btrfs_delete_inode,
 832         .put_super      = btrfs_put_super,
 833         .sync_fs        = btrfs_sync_fs,
 834         .show_options   = btrfs_show_options,
 835         .write_inode    = btrfs_write_inode,
 836         .dirty_inode    = btrfs_dirty_inode,
 837         .alloc_inode    = btrfs_alloc_inode,
 838         .destroy_inode  = btrfs_destroy_inode,
 839         .statfs         = btrfs_statfs,
 840         .remount_fs     = btrfs_remount,
 841         .freeze_fs      = btrfs_freeze,
 842         .unfreeze_fs    = btrfs_unfreeze,
 843 };
 844
 845 static const struct file_operations btrfs_ctl_fops = {
 846         .unlocked_ioctl  = btrfs_control_ioctl,
 847         .compat_ioctl = btrfs_control_ioctl,
 848         .owner   = THIS_MODULE,
 849 };
 850
 851 static struct miscdevice btrfs_misc = {
 852         .minor          = MISC_DYNAMIC_MINOR,
 853         .name           = "btrfs-control",
 854         .fops           = &btrfs_ctl_fops
 855 };
 856
 857 static int btrfs_interface_init(void)
 858 {
 859         return misc_register(&btrfs_misc);
 860 }
 861
 862 static void btrfs_interface_exit(void)
 863 {
 864         if (misc_deregister(&btrfs_misc) < 0)
 865                 printk(KERN_INFO "misc_deregister failed for control device");
 866 }
 867
 868 static int __init init_btrfs_fs(void)
 869 {
 870         int err;
 871
 872         err = btrfs_init_sysfs();
 873         if (err)
 874                 return err;
 875
 876         err = btrfs_init_cachep();
 877         if (err)
 878                 goto free_sysfs;
 879
 880         err = extent_io_init();
 881         if (err)
 882                 goto free_cachep;
 883
 884         err = extent_map_init();
 885         if (err)
 886                 goto free_extent_io;
 887
 888         err = btrfs_interface_init();
 889         if (err)
 890                 goto free_extent_map;
 891
 892         err = register_filesystem(&btrfs_fs_type);
 893         if (err)
 894                 goto unregister_ioctl;
 895
 896         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 897         return 0;
 898
 899 unregister_ioctl:
 900         btrfs_interface_exit();
 901 free_extent_map:
 902         extent_map_exit();
 903 free_extent_io:
 904         extent_io_exit();
 905 free_cachep:
 906         btrfs_destroy_cachep();
 907 free_sysfs:
 908         btrfs_exit_sysfs();
 909         return err;
 910 }
 911
 912 static void __exit exit_btrfs_fs(void)
 913 {
 914         btrfs_destroy_cachep();
 915         extent_map_exit();
 916         extent_io_exit();
 917         btrfs_interface_exit();
 918         unregister_filesystem(&btrfs_fs_type);
 919         btrfs_exit_sysfs();
 920         btrfs_cleanup_fs_uuids();
 921         btrfs_zlib_exit();
 922 }
 923
 924 module_init(init_btrfs_fs)
 925 module_exit(exit_btrfs_fs)
 926
 927 MODULE_LICENSE("GPL");