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