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         (void)ret; /* FIXME: need to fix VFS to return error? */
  66 }
  67
  68 enum {
  69         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
  70         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
  71         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
  72         Opt_compress_force, Opt_notreelog, Opt_ratio, Opt_flushoncommit,
  73         Opt_discard, Opt_space_cache, Opt_clear_cache, Opt_err,
  74         Opt_user_subvol_rm_allowed,
  75 };
  76
  77 static match_table_t tokens = {
  78         {Opt_degraded, "degraded"},
  79         {Opt_subvol, "subvol=%s"},
  80         {Opt_subvolid, "subvolid=%d"},
  81         {Opt_device, "device=%s"},
  82         {Opt_nodatasum, "nodatasum"},
  83         {Opt_nodatacow, "nodatacow"},
  84         {Opt_nobarrier, "nobarrier"},
  85         {Opt_max_inline, "max_inline=%s"},
  86         {Opt_alloc_start, "alloc_start=%s"},
  87         {Opt_thread_pool, "thread_pool=%d"},
  88         {Opt_compress, "compress"},
  89         {Opt_compress_force, "compress-force"},
  90         {Opt_ssd, "ssd"},
  91         {Opt_ssd_spread, "ssd_spread"},
  92         {Opt_nossd, "nossd"},
  93         {Opt_noacl, "noacl"},
  94         {Opt_notreelog, "notreelog"},
  95         {Opt_flushoncommit, "flushoncommit"},
  96         {Opt_ratio, "metadata_ratio=%d"},
  97         {Opt_discard, "discard"},
  98         {Opt_space_cache, "space_cache"},
  99         {Opt_clear_cache, "clear_cache"},
 100         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 101         {Opt_err, NULL},
 102 };
 103
 104 /*
 105  * Regular mount options parser.  Everything that is needed only when
 106  * reading in a new superblock is parsed here.
 107  */
 108 int btrfs_parse_options(struct btrfs_root *root, char *options)
 109 {
 110         struct btrfs_fs_info *info = root->fs_info;
 111         substring_t args[MAX_OPT_ARGS];
 112         char *p, *num, *orig;
 113         int intarg;
 114         int ret = 0;
 115
 116         if (!options)
 117                 return 0;
 118
 119         /*
 120          * strsep changes the string, duplicate it because parse_options
 121          * gets called twice
 122          */
 123         options = kstrdup(options, GFP_NOFS);
 124         if (!options)
 125                 return -ENOMEM;
 126
 127         orig = options;
 128
 129         while ((p = strsep(&options, ",")) != NULL) {
 130                 int token;
 131                 if (!*p)
 132                         continue;
 133
 134                 token = match_token(p, tokens, args);
 135                 switch (token) {
 136                 case Opt_degraded:
 137                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 138                         btrfs_set_opt(info->mount_opt, DEGRADED);
 139                         break;
 140                 case Opt_subvol:
 141                 case Opt_subvolid:
 142                 case Opt_device:
 143                         /*
 144                          * These are parsed by btrfs_parse_early_options
 145                          * and can be happily ignored here.
 146                          */
 147                         break;
 148                 case Opt_nodatasum:
 149                         printk(KERN_INFO "btrfs: setting nodatasum\n");
 150                         btrfs_set_opt(info->mount_opt, NODATASUM);
 151                         break;
 152                 case Opt_nodatacow:
 153                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 154                         btrfs_set_opt(info->mount_opt, NODATACOW);
 155                         btrfs_set_opt(info->mount_opt, NODATASUM);
 156                         break;
 157                 case Opt_compress:
 158                         printk(KERN_INFO "btrfs: use compression\n");
 159                         btrfs_set_opt(info->mount_opt, COMPRESS);
 160                         break;
 161                 case Opt_compress_force:
 162                         printk(KERN_INFO "btrfs: forcing compression\n");
 163                         btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 164                         btrfs_set_opt(info->mount_opt, COMPRESS);
 165                         break;
 166                 case Opt_ssd:
 167                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 168                         btrfs_set_opt(info->mount_opt, SSD);
 169                         break;
 170                 case Opt_ssd_spread:
 171                         printk(KERN_INFO "btrfs: use spread ssd "
 172                                "allocation scheme\n");
 173                         btrfs_set_opt(info->mount_opt, SSD);
 174                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 175                         break;
 176                 case Opt_nossd:
 177                         printk(KERN_INFO "btrfs: not using ssd allocation "
 178                                "scheme\n");
 179                         btrfs_set_opt(info->mount_opt, NOSSD);
 180                         btrfs_clear_opt(info->mount_opt, SSD);
 181                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 182                         break;
 183                 case Opt_nobarrier:
 184                         printk(KERN_INFO "btrfs: turning off barriers\n");
 185                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 186                         break;
 187                 case Opt_thread_pool:
 188                         intarg = 0;
 189                         match_int(&args[0], &intarg);
 190                         if (intarg) {
 191                                 info->thread_pool_size = intarg;
 192                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 193                                        info->thread_pool_size);
 194                         }
 195                         break;
 196                 case Opt_max_inline:
 197                         num = match_strdup(&args[0]);
 198                         if (num) {
 199                                 info->max_inline = memparse(num, NULL);
 200                                 kfree(num);
 201
 202                                 if (info->max_inline) {
 203                                         info->max_inline = max_t(u64,
 204                                                 info->max_inline,
 205                                                 root->sectorsize);
 206                                 }
 207                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 208                                         (unsigned long long)info->max_inline);
 209                         }
 210                         break;
 211                 case Opt_alloc_start:
 212                         num = match_strdup(&args[0]);
 213                         if (num) {
 214                                 info->alloc_start = memparse(num, NULL);
 215                                 kfree(num);
 216                                 printk(KERN_INFO
 217                                         "btrfs: allocations start at %llu\n",
 218                                         (unsigned long long)info->alloc_start);
 219                         }
 220                         break;
 221                 case Opt_noacl:
 222                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 223                         break;
 224                 case Opt_notreelog:
 225                         printk(KERN_INFO "btrfs: disabling tree log\n");
 226                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 227                         break;
 228                 case Opt_flushoncommit:
 229                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 230                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 231                         break;
 232                 case Opt_ratio:
 233                         intarg = 0;
 234                         match_int(&args[0], &intarg);
 235                         if (intarg) {
 236                                 info->metadata_ratio = intarg;
 237                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 238                                        info->metadata_ratio);
 239                         }
 240                         break;
 241                 case Opt_discard:
 242                         btrfs_set_opt(info->mount_opt, DISCARD);
 243                         break;
 244                 case Opt_space_cache:
 245                         printk(KERN_INFO "btrfs: enabling disk space caching\n");
 246                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 247                         break;
 248                 case Opt_clear_cache:
 249                         printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 250                         btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
 251                         break;
 252                 case Opt_user_subvol_rm_allowed:
 253                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 254                         break;
 255                 case Opt_err:
 256                         printk(KERN_INFO "btrfs: unrecognized mount option "
 257                                "'%s'\n", p);
 258                         ret = -EINVAL;
 259                         goto out;
 260                 default:
 261                         break;
 262                 }
 263         }
 264 out:
 265         kfree(orig);
 266         return ret;
 267 }
 268
 269 /*
 270  * Parse mount options that are required early in the mount process.
 271  *
 272  * All other options will be parsed on much later in the mount process and
 273  * only when we need to allocate a new super block.
 274  */
 275 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 276                 void *holder, char **subvol_name, u64 *subvol_objectid,
 277                 struct btrfs_fs_devices **fs_devices)
 278 {
 279         substring_t args[MAX_OPT_ARGS];
 280         char *opts, *p;
 281         int error = 0;
 282         int intarg;
 283
 284         if (!options)
 285                 goto out;
 286
 287         /*
 288          * strsep changes the string, duplicate it because parse_options
 289          * gets called twice
 290          */
 291         opts = kstrdup(options, GFP_KERNEL);
 292         if (!opts)
 293                 return -ENOMEM;
 294
 295         while ((p = strsep(&opts, ",")) != NULL) {
 296                 int token;
 297                 if (!*p)
 298                         continue;
 299
 300                 token = match_token(p, tokens, args);
 301                 switch (token) {
 302                 case Opt_subvol:
 303                         *subvol_name = match_strdup(&args[0]);
 304                         break;
 305                 case Opt_subvolid:
 306                         intarg = 0;
 307                         error = match_int(&args[0], &intarg);
 308                         if (!error) {
 309                                 /* we want the original fs_tree */
 310                                 if (!intarg)
 311                                         *subvol_objectid =
 312                                                 BTRFS_FS_TREE_OBJECTID;
 313                                 else
 314                                         *subvol_objectid = intarg;
 315                         }
 316                         break;
 317                 case Opt_device:
 318                         error = btrfs_scan_one_device(match_strdup(&args[0]),
 319                                         flags, holder, fs_devices);
 320                         if (error)
 321                                 goto out_free_opts;
 322                         break;
 323                 default:
 324                         break;
 325                 }
 326         }
 327
 328  out_free_opts:
 329         kfree(opts);
 330  out:
 331         /*
 332          * If no subvolume name is specified we use the default one.  Allocate
 333          * a copy of the string "." here so that code later in the
 334          * mount path doesn't care if it's the default volume or another one.
 335          */
 336         if (!*subvol_name) {
 337                 *subvol_name = kstrdup(".", GFP_KERNEL);
 338                 if (!*subvol_name)
 339                         return -ENOMEM;
 340         }
 341         return error;
 342 }
 343
 344 static struct dentry *get_default_root(struct super_block *sb,
 345                                        u64 subvol_objectid)
 346 {
 347         struct btrfs_root *root = sb->s_fs_info;
 348         struct btrfs_root *new_root;
 349         struct btrfs_dir_item *di;
 350         struct btrfs_path *path;
 351         struct btrfs_key location;
 352         struct inode *inode;
 353         struct dentry *dentry;
 354         u64 dir_id;
 355         int new = 0;
 356
 357         /*
 358          * We have a specific subvol we want to mount, just setup location and
 359          * go look up the root.
 360          */
 361         if (subvol_objectid) {
 362                 location.objectid = subvol_objectid;
 363                 location.type = BTRFS_ROOT_ITEM_KEY;
 364                 location.offset = (u64)-1;
 365                 goto find_root;
 366         }
 367
 368         path = btrfs_alloc_path();
 369         if (!path)
 370                 return ERR_PTR(-ENOMEM);
 371         path->leave_spinning = 1;
 372
 373         /*
 374          * Find the "default" dir item which points to the root item that we
 375          * will mount by default if we haven't been given a specific subvolume
 376          * to mount.
 377          */
 378         dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
 379         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 380         if (IS_ERR(di))
 381                 return ERR_CAST(di);
 382         if (!di) {
 383                 /*
 384                  * Ok the default dir item isn't there.  This is weird since
 385                  * it's always been there, but don't freak out, just try and
 386                  * mount to root most subvolume.
 387                  */
 388                 btrfs_free_path(path);
 389                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
 390                 new_root = root->fs_info->fs_root;
 391                 goto setup_root;
 392         }
 393
 394         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 395         btrfs_free_path(path);
 396
 397 find_root:
 398         new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
 399         if (IS_ERR(new_root))
 400                 return ERR_CAST(new_root);
 401
 402         if (btrfs_root_refs(&new_root->root_item) == 0)
 403                 return ERR_PTR(-ENOENT);
 404
 405         dir_id = btrfs_root_dirid(&new_root->root_item);
 406 setup_root:
 407         location.objectid = dir_id;
 408         location.type = BTRFS_INODE_ITEM_KEY;
 409         location.offset = 0;
 410
 411         inode = btrfs_iget(sb, &location, new_root, &new);
 412         if (IS_ERR(inode))
 413                 return ERR_CAST(inode);
 414
 415         /*
 416          * If we're just mounting the root most subvol put the inode and return
 417          * a reference to the dentry.  We will have already gotten a reference
 418          * to the inode in btrfs_fill_super so we're good to go.
 419          */
 420         if (!new && sb->s_root->d_inode == inode) {
 421                 iput(inode);
 422                 return dget(sb->s_root);
 423         }
 424
 425         if (new) {
 426                 const struct qstr name = { .name = "/", .len = 1 };
 427
 428                 /*
 429                  * New inode, we need to make the dentry a sibling of s_root so
 430                  * everything gets cleaned up properly on unmount.
 431                  */
 432                 dentry = d_alloc(sb->s_root, &name);
 433                 if (!dentry) {
 434                         iput(inode);
 435                         return ERR_PTR(-ENOMEM);
 436                 }
 437                 d_splice_alias(inode, dentry);
 438         } else {
 439                 /*
 440                  * We found the inode in cache, just find a dentry for it and
 441                  * put the reference to the inode we just got.
 442                  */
 443                 dentry = d_find_alias(inode);
 444                 iput(inode);
 445         }
 446
 447         return dentry;
 448 }
 449
 450 static int btrfs_fill_super(struct super_block *sb,
 451                             struct btrfs_fs_devices *fs_devices,
 452                             void *data, int silent)
 453 {
 454         struct inode *inode;
 455         struct dentry *root_dentry;
 456         struct btrfs_root *tree_root;
 457         struct btrfs_key key;
 458         int err;
 459
 460         sb->s_maxbytes = MAX_LFS_FILESIZE;
 461         sb->s_magic = BTRFS_SUPER_MAGIC;
 462         sb->s_op = &btrfs_super_ops;
 463         sb->s_export_op = &btrfs_export_ops;
 464         sb->s_xattr = btrfs_xattr_handlers;
 465         sb->s_time_gran = 1;
 466 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 467         sb->s_flags |= MS_POSIXACL;
 468 #endif
 469
 470         tree_root = open_ctree(sb, fs_devices, (char *)data);
 471
 472         if (IS_ERR(tree_root)) {
 473                 printk("btrfs: open_ctree failed\n");
 474                 return PTR_ERR(tree_root);
 475         }
 476         sb->s_fs_info = tree_root;
 477
 478         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 479         key.type = BTRFS_INODE_ITEM_KEY;
 480         key.offset = 0;
 481         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);
 482         if (IS_ERR(inode)) {
 483                 err = PTR_ERR(inode);
 484                 goto fail_close;
 485         }
 486
 487         root_dentry = d_alloc_root(inode);
 488         if (!root_dentry) {
 489                 iput(inode);
 490                 err = -ENOMEM;
 491                 goto fail_close;
 492         }
 493
 494         sb->s_root = root_dentry;
 495
 496         save_mount_options(sb, data);
 497         return 0;
 498
 499 fail_close:
 500         close_ctree(tree_root);
 501         return err;
 502 }
 503
 504 int btrfs_sync_fs(struct super_block *sb, int wait)
 505 {
 506         struct btrfs_trans_handle *trans;
 507         struct btrfs_root *root = btrfs_sb(sb);
 508         int ret;
 509
 510         if (!wait) {
 511                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 512                 return 0;
 513         }
 514
 515         btrfs_start_delalloc_inodes(root, 0);
 516         btrfs_wait_ordered_extents(root, 0, 0);
 517
 518         trans = btrfs_start_transaction(root, 0);
 519         ret = btrfs_commit_transaction(trans, root);
 520         return ret;
 521 }
 522
 523 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 524 {
 525         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 526         struct btrfs_fs_info *info = root->fs_info;
 527
 528         if (btrfs_test_opt(root, DEGRADED))
 529                 seq_puts(seq, ",degraded");
 530         if (btrfs_test_opt(root, NODATASUM))
 531                 seq_puts(seq, ",nodatasum");
 532         if (btrfs_test_opt(root, NODATACOW))
 533                 seq_puts(seq, ",nodatacow");
 534         if (btrfs_test_opt(root, NOBARRIER))
 535                 seq_puts(seq, ",nobarrier");
 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         /*
 570          * If this super block is going away, return false as it
 571          * can't match as an existing super block.
 572          */
 573         if (!atomic_read(&s->s_active))
 574                 return 0;
 575         return root->fs_info->fs_devices == test_fs_devices;
 576 }
 577
 578 /*
 579  * Find a superblock for the given device / mount point.
 580  *
 581  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 582  *        for multiple device setup.  Make sure to keep it in sync.
 583  */
 584 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 585                 const char *dev_name, void *data, struct vfsmount *mnt)
 586 {
 587         struct block_device *bdev = NULL;
 588         struct super_block *s;
 589         struct dentry *root;
 590         struct btrfs_fs_devices *fs_devices = NULL;
 591         fmode_t mode = FMODE_READ;
 592         char *subvol_name = NULL;
 593         u64 subvol_objectid = 0;
 594         int error = 0;
 595
 596         if (!(flags & MS_RDONLY))
 597                 mode |= FMODE_WRITE;
 598
 599         error = btrfs_parse_early_options(data, mode, fs_type,
 600                                           &subvol_name, &subvol_objectid,
 601                                           &fs_devices);
 602         if (error)
 603                 return error;
 604
 605         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
 606         if (error)
 607                 goto error_free_subvol_name;
 608
 609         error = btrfs_open_devices(fs_devices, mode, fs_type);
 610         if (error)
 611                 goto error_free_subvol_name;
 612
 613         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 614                 error = -EACCES;
 615                 goto error_close_devices;
 616         }
 617
 618         bdev = fs_devices->latest_bdev;
 619         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
 620         if (IS_ERR(s))
 621                 goto error_s;
 622
 623         if (s->s_root) {
 624                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 625                         deactivate_locked_super(s);
 626                         error = -EBUSY;
 627                         goto error_close_devices;
 628                 }
 629
 630                 btrfs_close_devices(fs_devices);
 631         } else {
 632                 char b[BDEVNAME_SIZE];
 633
 634                 s->s_flags = flags;
 635                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 636                 error = btrfs_fill_super(s, fs_devices, data,
 637                                          flags & MS_SILENT ? 1 : 0);
 638                 if (error) {
 639                         deactivate_locked_super(s);
 640                         goto error_free_subvol_name;
 641                 }
 642
 643                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 644                 s->s_flags |= MS_ACTIVE;
 645         }
 646
 647         root = get_default_root(s, subvol_objectid);
 648         if (IS_ERR(root)) {
 649                 error = PTR_ERR(root);
 650                 deactivate_locked_super(s);
 651                 goto error_free_subvol_name;
 652         }
 653         /* if they gave us a subvolume name bind mount into that */
 654         if (strcmp(subvol_name, ".")) {
 655                 struct dentry *new_root;
 656                 mutex_lock(&root->d_inode->i_mutex);
 657                 new_root = lookup_one_len(subvol_name, root,
 658                                       strlen(subvol_name));
 659                 mutex_unlock(&root->d_inode->i_mutex);
 660
 661                 if (IS_ERR(new_root)) {
 662                         deactivate_locked_super(s);
 663                         error = PTR_ERR(new_root);
 664                         dput(root);
 665                         goto error_free_subvol_name;
 666                 }
 667                 if (!new_root->d_inode) {
 668                         dput(root);
 669                         dput(new_root);
 670                         deactivate_locked_super(s);
 671                         error = -ENXIO;
 672                         goto error_free_subvol_name;
 673                 }
 674                 dput(root);
 675                 root = new_root;
 676         }
 677
 678         mnt->mnt_sb = s;
 679         mnt->mnt_root = root;
 680
 681         kfree(subvol_name);
 682         return 0;
 683
 684 error_s:
 685         error = PTR_ERR(s);
 686 error_close_devices:
 687         btrfs_close_devices(fs_devices);
 688 error_free_subvol_name:
 689         kfree(subvol_name);
 690         return error;
 691 }
 692
 693 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 694 {
 695         struct btrfs_root *root = btrfs_sb(sb);
 696         int ret;
 697
 698         ret = btrfs_parse_options(root, data);
 699         if (ret)
 700                 return -EINVAL;
 701
 702         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 703                 return 0;
 704
 705         if (*flags & MS_RDONLY) {
 706                 sb->s_flags |= MS_RDONLY;
 707
 708                 ret =  btrfs_commit_super(root);
 709                 WARN_ON(ret);
 710         } else {
 711                 if (root->fs_info->fs_devices->rw_devices == 0)
 712                         return -EACCES;
 713
 714                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 715                         return -EINVAL;
 716
 717                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 718                 WARN_ON(ret);
 719
 720                 /* recover relocation */
 721                 ret = btrfs_recover_relocation(root);
 722                 WARN_ON(ret);
 723
 724                 sb->s_flags &= ~MS_RDONLY;
 725         }
 726
 727         return 0;
 728 }
 729
 730 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 731 {
 732         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 733         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 734         struct list_head *head = &root->fs_info->space_info;
 735         struct btrfs_space_info *found;
 736         u64 total_used = 0;
 737         u64 total_used_data = 0;
 738         int bits = dentry->d_sb->s_blocksize_bits;
 739         __be32 *fsid = (__be32 *)root->fs_info->fsid;
 740
 741         rcu_read_lock();
 742         list_for_each_entry_rcu(found, head, list) {
 743                 if (found->flags & (BTRFS_BLOCK_GROUP_METADATA |
 744                                     BTRFS_BLOCK_GROUP_SYSTEM))
 745                         total_used_data += found->disk_total;
 746                 else
 747                         total_used_data += found->disk_used;
 748                 total_used += found->disk_used;
 749         }
 750         rcu_read_unlock();
 751
 752         buf->f_namelen = BTRFS_NAME_LEN;
 753         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 754         buf->f_bfree = buf->f_blocks - (total_used >> bits);
 755         buf->f_bavail = buf->f_blocks - (total_used_data >> bits);
 756         buf->f_bsize = dentry->d_sb->s_blocksize;
 757         buf->f_type = BTRFS_SUPER_MAGIC;
 758
 759         /* We treat it as constant endianness (it doesn't matter _which_)
 760            because we want the fsid to come out the same whether mounted
 761            on a big-endian or little-endian host */
 762         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
 763         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
 764         /* Mask in the root object ID too, to disambiguate subvols */
 765         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
 766         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
 767
 768         return 0;
 769 }
 770
 771 static struct file_system_type btrfs_fs_type = {
 772         .owner          = THIS_MODULE,
 773         .name           = "btrfs",
 774         .get_sb         = btrfs_get_sb,
 775         .kill_sb        = kill_anon_super,
 776         .fs_flags       = FS_REQUIRES_DEV,
 777 };
 778
 779 /*
 780  * used by btrfsctl to scan devices when no FS is mounted
 781  */
 782 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 783                                 unsigned long arg)
 784 {
 785         struct btrfs_ioctl_vol_args *vol;
 786         struct btrfs_fs_devices *fs_devices;
 787         int ret = -ENOTTY;
 788
 789         if (!capable(CAP_SYS_ADMIN))
 790                 return -EPERM;
 791
 792         vol = memdup_user((void __user *)arg, sizeof(*vol));
 793         if (IS_ERR(vol))
 794                 return PTR_ERR(vol);
 795
 796         switch (cmd) {
 797         case BTRFS_IOC_SCAN_DEV:
 798                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
 799                                             &btrfs_fs_type, &fs_devices);
 800                 break;
 801         }
 802
 803         kfree(vol);
 804         return ret;
 805 }
 806
 807 static int btrfs_freeze(struct super_block *sb)
 808 {
 809         struct btrfs_root *root = btrfs_sb(sb);
 810         mutex_lock(&root->fs_info->transaction_kthread_mutex);
 811         mutex_lock(&root->fs_info->cleaner_mutex);
 812         return 0;
 813 }
 814
 815 static int btrfs_unfreeze(struct super_block *sb)
 816 {
 817         struct btrfs_root *root = btrfs_sb(sb);
 818         mutex_unlock(&root->fs_info->cleaner_mutex);
 819         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 820         return 0;
 821 }
 822
 823 static const struct super_operations btrfs_super_ops = {
 824         .drop_inode     = btrfs_drop_inode,
 825         .evict_inode    = btrfs_evict_inode,
 826         .put_super      = btrfs_put_super,
 827         .sync_fs        = btrfs_sync_fs,
 828         .show_options   = btrfs_show_options,
 829         .write_inode    = btrfs_write_inode,
 830         .dirty_inode    = btrfs_dirty_inode,
 831         .alloc_inode    = btrfs_alloc_inode,
 832         .destroy_inode  = btrfs_destroy_inode,
 833         .statfs         = btrfs_statfs,
 834         .remount_fs     = btrfs_remount,
 835         .freeze_fs      = btrfs_freeze,
 836         .unfreeze_fs    = btrfs_unfreeze,
 837 };
 838
 839 static const struct file_operations btrfs_ctl_fops = {
 840         .unlocked_ioctl  = btrfs_control_ioctl,
 841         .compat_ioctl = btrfs_control_ioctl,
 842         .owner   = THIS_MODULE,
 843 };
 844
 845 static struct miscdevice btrfs_misc = {
 846         .minor          = BTRFS_MINOR,
 847         .name           = "btrfs-control",
 848         .fops           = &btrfs_ctl_fops
 849 };
 850
 851 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
 852 MODULE_ALIAS("devname:btrfs-control");
 853
 854 static int btrfs_interface_init(void)
 855 {
 856         return misc_register(&btrfs_misc);
 857 }
 858
 859 static void btrfs_interface_exit(void)
 860 {
 861         if (misc_deregister(&btrfs_misc) < 0)
 862                 printk(KERN_INFO "misc_deregister failed for control device");
 863 }
 864
 865 static int __init init_btrfs_fs(void)
 866 {
 867         int err;
 868
 869         err = btrfs_init_sysfs();
 870         if (err)
 871                 return err;
 872
 873         err = btrfs_init_cachep();
 874         if (err)
 875                 goto free_sysfs;
 876
 877         err = extent_io_init();
 878         if (err)
 879                 goto free_cachep;
 880
 881         err = extent_map_init();
 882         if (err)
 883                 goto free_extent_io;
 884
 885         err = btrfs_interface_init();
 886         if (err)
 887                 goto free_extent_map;
 888
 889         err = register_filesystem(&btrfs_fs_type);
 890         if (err)
 891                 goto unregister_ioctl;
 892
 893         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
 894         return 0;
 895
 896 unregister_ioctl:
 897         btrfs_interface_exit();
 898 free_extent_map:
 899         extent_map_exit();
 900 free_extent_io:
 901         extent_io_exit();
 902 free_cachep:
 903         btrfs_destroy_cachep();
 904 free_sysfs:
 905         btrfs_exit_sysfs();
 906         return err;
 907 }
 908
 909 static void __exit exit_btrfs_fs(void)
 910 {
 911         btrfs_destroy_cachep();
 912         extent_map_exit();
 913         extent_io_exit();
 914         btrfs_interface_exit();
 915         unregister_filesystem(&btrfs_fs_type);
 916         btrfs_exit_sysfs();
 917         btrfs_cleanup_fs_uuids();
 918         btrfs_zlib_exit();
 919 }
 920
 921 module_init(init_btrfs_fs)
 922 module_exit(exit_btrfs_fs)
 923
 924 MODULE_LICENSE("GPL");