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