fs/btrfs/super.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/module.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/fs.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/highmem.h>
  25 #include <linux/time.h>
  26 #include <linux/init.h>
  27 #include <linux/seq_file.h>
  28 #include <linux/string.h>
  29 #include <linux/backing-dev.h>
  30 #include <linux/mount.h>
  31 #include <linux/mpage.h>
  32 #include <linux/swap.h>
  33 #include <linux/writeback.h>
  34 #include <linux/statfs.h>
  35 #include <linux/compat.h>
  36 #include <linux/parser.h>
  37 #include <linux/ctype.h>
  38 #include <linux/namei.h>
  39 #include <linux/miscdevice.h>
  40 #include <linux/magic.h>
  41 #include <linux/slab.h>
  42 #include <linux/cleancache.h>
  43 #include <linux/ratelimit.h>
  44 #include <linux/btrfs.h>
  45 #include "delayed-inode.h"
  46 #include "ctree.h"
  47 #include "disk-io.h"
  48 #include "transaction.h"
  49 #include "btrfs_inode.h"
  50 #include "print-tree.h"
  51 #include "hash.h"
  52 #include "props.h"
  53 #include "xattr.h"
  54 #include "volumes.h"
  55 #include "export.h"
  56 #include "compression.h"
  57 #include "rcu-string.h"
  58 #include "dev-replace.h"
  59 #include "free-space-cache.h"
  60 #include "backref.h"
  61 #include "tests/btrfs-tests.h"
  62
  63 #include "qgroup.h"
  64 #define CREATE_TRACE_POINTS
  65 #include <trace/events/btrfs.h>
  66
  67 static const struct super_operations btrfs_super_ops;
  68 static struct file_system_type btrfs_fs_type;
  69
  70 static int btrfs_remount(struct super_block *sb, int *flags, char *data);
  71
  72 const char *btrfs_decode_error(int errno)
  73 {
  74         char *errstr = "unknown";
  75
  76         switch (errno) {
  77         case -EIO:
  78                 errstr = "IO failure";
  79                 break;
  80         case -ENOMEM:
  81                 errstr = "Out of memory";
  82                 break;
  83         case -EROFS:
  84                 errstr = "Readonly filesystem";
  85                 break;
  86         case -EEXIST:
  87                 errstr = "Object already exists";
  88                 break;
  89         case -ENOSPC:
  90                 errstr = "No space left";
  91                 break;
  92         case -ENOENT:
  93                 errstr = "No such entry";
  94                 break;
  95         }
  96
  97         return errstr;
  98 }
  99
 100 /* btrfs handle error by forcing the filesystem readonly */
 101 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
 102 {
 103         struct super_block *sb = fs_info->sb;
 104
 105         if (sb->s_flags & MS_RDONLY)
 106                 return;
 107
 108         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 109                 sb->s_flags |= MS_RDONLY;
 110                 btrfs_info(fs_info, "forced readonly");
 111                 /*
 112                  * Note that a running device replace operation is not
 113                  * canceled here although there is no way to update
 114                  * the progress. It would add the risk of a deadlock,
 115                  * therefore the canceling is omitted. The only penalty
 116                  * is that some I/O remains active until the procedure
 117                  * completes. The next time when the filesystem is
 118                  * mounted writeable again, the device replace
 119                  * operation continues.
 120                  */
 121         }
 122 }
 123
 124 /*
 125  * __btrfs_handle_fs_error decodes expected errors from the caller and
 126  * invokes the approciate error response.
 127  */
 128 __cold
 129 void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function,
 130                        unsigned int line, int errno, const char *fmt, ...)
 131 {
 132         struct super_block *sb = fs_info->sb;
 133 #ifdef CONFIG_PRINTK
 134         const char *errstr;
 135 #endif
 136
 137         /*
 138          * Special case: if the error is EROFS, and we're already
 139          * under MS_RDONLY, then it is safe here.
 140          */
 141         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 142                 return;
 143
 144 #ifdef CONFIG_PRINTK
 145         errstr = btrfs_decode_error(errno);
 146         if (fmt) {
 147                 struct va_format vaf;
 148                 va_list args;
 149
 150                 va_start(args, fmt);
 151                 vaf.fmt = fmt;
 152                 vaf.va = &args;
 153
 154                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s (%pV)\n",
 155                         sb->s_id, function, line, errno, errstr, &vaf);
 156                 va_end(args);
 157         } else {
 158                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s\n",
 159                         sb->s_id, function, line, errno, errstr);
 160         }
 161 #endif
 162
 163         /*
 164          * Today we only save the error info to memory.  Long term we'll
 165          * also send it down to the disk
 166          */
 167         set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
 168
 169         /* Don't go through full error handling during mount */
 170         if (sb->s_flags & MS_BORN)
 171                 btrfs_handle_error(fs_info);
 172 }
 173
 174 #ifdef CONFIG_PRINTK
 175 static const char * const logtypes[] = {
 176         "emergency",
 177         "alert",
 178         "critical",
 179         "error",
 180         "warning",
 181         "notice",
 182         "info",
 183         "debug",
 184 };
 185
 186
 187 /*
 188  * Use one ratelimit state per log level so that a flood of less important
 189  * messages doesn't cause more important ones to be dropped.
 190  */
 191 static struct ratelimit_state printk_limits[] = {
 192         RATELIMIT_STATE_INIT(printk_limits[0], DEFAULT_RATELIMIT_INTERVAL, 100),
 193         RATELIMIT_STATE_INIT(printk_limits[1], DEFAULT_RATELIMIT_INTERVAL, 100),
 194         RATELIMIT_STATE_INIT(printk_limits[2], DEFAULT_RATELIMIT_INTERVAL, 100),
 195         RATELIMIT_STATE_INIT(printk_limits[3], DEFAULT_RATELIMIT_INTERVAL, 100),
 196         RATELIMIT_STATE_INIT(printk_limits[4], DEFAULT_RATELIMIT_INTERVAL, 100),
 197         RATELIMIT_STATE_INIT(printk_limits[5], DEFAULT_RATELIMIT_INTERVAL, 100),
 198         RATELIMIT_STATE_INIT(printk_limits[6], DEFAULT_RATELIMIT_INTERVAL, 100),
 199         RATELIMIT_STATE_INIT(printk_limits[7], DEFAULT_RATELIMIT_INTERVAL, 100),
 200 };
 201
 202 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 203 {
 204         struct super_block *sb = fs_info->sb;
 205         char lvl[4];
 206         struct va_format vaf;
 207         va_list args;
 208         const char *type = logtypes[4];
 209         int kern_level;
 210         struct ratelimit_state *ratelimit;
 211
 212         va_start(args, fmt);
 213
 214         kern_level = printk_get_level(fmt);
 215         if (kern_level) {
 216                 size_t size = printk_skip_level(fmt) - fmt;
 217                 memcpy(lvl, fmt,  size);
 218                 lvl[size] = '\0';
 219                 fmt += size;
 220                 type = logtypes[kern_level - '0'];
 221                 ratelimit = &printk_limits[kern_level - '0'];
 222         } else {
 223                 *lvl = '\0';
 224                 /* Default to debug output */
 225                 ratelimit = &printk_limits[7];
 226         }
 227
 228         vaf.fmt = fmt;
 229         vaf.va = &args;
 230
 231         if (__ratelimit(ratelimit))
 232                 printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
 233
 234         va_end(args);
 235 }
 236 #endif
 237
 238 /*
 239  * We only mark the transaction aborted and then set the file system read-only.
 240  * This will prevent new transactions from starting or trying to join this
 241  * one.
 242  *
 243  * This means that error recovery at the call site is limited to freeing
 244  * any local memory allocations and passing the error code up without
 245  * further cleanup. The transaction should complete as it normally would
 246  * in the call path but will return -EIO.
 247  *
 248  * We'll complete the cleanup in btrfs_end_transaction and
 249  * btrfs_commit_transaction.
 250  */
 251 __cold
 252 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 253                                const char *function,
 254                                unsigned int line, int errno)
 255 {
 256         struct btrfs_fs_info *fs_info = trans->fs_info;
 257
 258         trans->aborted = errno;
 259         /* Nothing used. The other threads that have joined this
 260          * transaction may be able to continue. */
 261         if (!trans->dirty && list_empty(&trans->new_bgs)) {
 262                 const char *errstr;
 263
 264                 errstr = btrfs_decode_error(errno);
 265                 btrfs_warn(fs_info,
 266                            "%s:%d: Aborting unused transaction(%s).",
 267                            function, line, errstr);
 268                 return;
 269         }
 270         ACCESS_ONCE(trans->transaction->aborted) = errno;
 271         /* Wake up anybody who may be waiting on this transaction */
 272         wake_up(&fs_info->transaction_wait);
 273         wake_up(&fs_info->transaction_blocked_wait);
 274         __btrfs_handle_fs_error(fs_info, function, line, errno, NULL);
 275 }
 276 /*
 277  * __btrfs_panic decodes unexpected, fatal errors from the caller,
 278  * issues an alert, and either panics or BUGs, depending on mount options.
 279  */
 280 __cold
 281 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 282                    unsigned int line, int errno, const char *fmt, ...)
 283 {
 284         char *s_id = "<unknown>";
 285         const char *errstr;
 286         struct va_format vaf = { .fmt = fmt };
 287         va_list args;
 288
 289         if (fs_info)
 290                 s_id = fs_info->sb->s_id;
 291
 292         va_start(args, fmt);
 293         vaf.va = &args;
 294
 295         errstr = btrfs_decode_error(errno);
 296         if (fs_info && (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR))
 297                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
 298                         s_id, function, line, &vaf, errno, errstr);
 299
 300         btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
 301                    function, line, &vaf, errno, errstr);
 302         va_end(args);
 303         /* Caller calls BUG() */
 304 }
 305
 306 static void btrfs_put_super(struct super_block *sb)
 307 {
 308         close_ctree(btrfs_sb(sb)->tree_root);
 309 }
 310
 311 enum {
 312         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 313         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 314         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 315         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 316         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 317         Opt_space_cache, Opt_space_cache_version, Opt_clear_cache,
 318         Opt_user_subvol_rm_allowed, Opt_enospc_debug, Opt_subvolrootid,
 319         Opt_defrag, Opt_inode_cache, Opt_no_space_cache, Opt_recovery,
 320         Opt_skip_balance, Opt_check_integrity,
 321         Opt_check_integrity_including_extent_data,
 322         Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
 323         Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
 324         Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
 325         Opt_datasum, Opt_treelog, Opt_noinode_cache, Opt_usebackuproot,
 326         Opt_nologreplay, Opt_norecovery,
 327 #ifdef CONFIG_BTRFS_DEBUG
 328         Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 329 #endif
 330         Opt_err,
 331 };
 332
 333 static const match_table_t tokens = {
 334         {Opt_degraded, "degraded"},
 335         {Opt_subvol, "subvol=%s"},
 336         {Opt_subvolid, "subvolid=%s"},
 337         {Opt_device, "device=%s"},
 338         {Opt_nodatasum, "nodatasum"},
 339         {Opt_datasum, "datasum"},
 340         {Opt_nodatacow, "nodatacow"},
 341         {Opt_datacow, "datacow"},
 342         {Opt_nobarrier, "nobarrier"},
 343         {Opt_barrier, "barrier"},
 344         {Opt_max_inline, "max_inline=%s"},
 345         {Opt_alloc_start, "alloc_start=%s"},
 346         {Opt_thread_pool, "thread_pool=%d"},
 347         {Opt_compress, "compress"},
 348         {Opt_compress_type, "compress=%s"},
 349         {Opt_compress_force, "compress-force"},
 350         {Opt_compress_force_type, "compress-force=%s"},
 351         {Opt_ssd, "ssd"},
 352         {Opt_ssd_spread, "ssd_spread"},
 353         {Opt_nossd, "nossd"},
 354         {Opt_acl, "acl"},
 355         {Opt_noacl, "noacl"},
 356         {Opt_notreelog, "notreelog"},
 357         {Opt_treelog, "treelog"},
 358         {Opt_nologreplay, "nologreplay"},
 359         {Opt_norecovery, "norecovery"},
 360         {Opt_flushoncommit, "flushoncommit"},
 361         {Opt_noflushoncommit, "noflushoncommit"},
 362         {Opt_ratio, "metadata_ratio=%d"},
 363         {Opt_discard, "discard"},
 364         {Opt_nodiscard, "nodiscard"},
 365         {Opt_space_cache, "space_cache"},
 366         {Opt_space_cache_version, "space_cache=%s"},
 367         {Opt_clear_cache, "clear_cache"},
 368         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 369         {Opt_enospc_debug, "enospc_debug"},
 370         {Opt_noenospc_debug, "noenospc_debug"},
 371         {Opt_subvolrootid, "subvolrootid=%d"},
 372         {Opt_defrag, "autodefrag"},
 373         {Opt_nodefrag, "noautodefrag"},
 374         {Opt_inode_cache, "inode_cache"},
 375         {Opt_noinode_cache, "noinode_cache"},
 376         {Opt_no_space_cache, "nospace_cache"},
 377         {Opt_recovery, "recovery"}, /* deprecated */
 378         {Opt_usebackuproot, "usebackuproot"},
 379         {Opt_skip_balance, "skip_balance"},
 380         {Opt_check_integrity, "check_int"},
 381         {Opt_check_integrity_including_extent_data, "check_int_data"},
 382         {Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
 383         {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
 384         {Opt_fatal_errors, "fatal_errors=%s"},
 385         {Opt_commit_interval, "commit=%d"},
 386 #ifdef CONFIG_BTRFS_DEBUG
 387         {Opt_fragment_data, "fragment=data"},
 388         {Opt_fragment_metadata, "fragment=metadata"},
 389         {Opt_fragment_all, "fragment=all"},
 390 #endif
 391         {Opt_err, NULL},
 392 };
 393
 394 /*
 395  * Regular mount options parser.  Everything that is needed only when
 396  * reading in a new superblock is parsed here.
 397  * XXX JDM: This needs to be cleaned up for remount.
 398  */
 399 int btrfs_parse_options(struct btrfs_root *root, char *options,
 400                         unsigned long new_flags)
 401 {
 402         struct btrfs_fs_info *info = root->fs_info;
 403         substring_t args[MAX_OPT_ARGS];
 404         char *p, *num, *orig = NULL;
 405         u64 cache_gen;
 406         int intarg;
 407         int ret = 0;
 408         char *compress_type;
 409         bool compress_force = false;
 410         enum btrfs_compression_type saved_compress_type;
 411         bool saved_compress_force;
 412         int no_compress = 0;
 413
 414         cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
 415         if (btrfs_fs_compat_ro(root->fs_info, FREE_SPACE_TREE))
 416                 btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
 417         else if (cache_gen)
 418                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 419
 420         /*
 421          * Even the options are empty, we still need to do extra check
 422          * against new flags
 423          */
 424         if (!options)
 425                 goto check;
 426
 427         /*
 428          * strsep changes the string, duplicate it because parse_options
 429          * gets called twice
 430          */
 431         options = kstrdup(options, GFP_NOFS);
 432         if (!options)
 433                 return -ENOMEM;
 434
 435         orig = options;
 436
 437         while ((p = strsep(&options, ",")) != NULL) {
 438                 int token;
 439                 if (!*p)
 440                         continue;
 441
 442                 token = match_token(p, tokens, args);
 443                 switch (token) {
 444                 case Opt_degraded:
 445                         btrfs_info(root->fs_info, "allowing degraded mounts");
 446                         btrfs_set_opt(info->mount_opt, DEGRADED);
 447                         break;
 448                 case Opt_subvol:
 449                 case Opt_subvolid:
 450                 case Opt_subvolrootid:
 451                 case Opt_device:
 452                         /*
 453                          * These are parsed by btrfs_parse_early_options
 454                          * and can be happily ignored here.
 455                          */
 456                         break;
 457                 case Opt_nodatasum:
 458                         btrfs_set_and_info(info, NODATASUM,
 459                                            "setting nodatasum");
 460                         break;
 461                 case Opt_datasum:
 462                         if (btrfs_test_opt(info, NODATASUM)) {
 463                                 if (btrfs_test_opt(info, NODATACOW))
 464                                         btrfs_info(root->fs_info,
 465                                                    "setting datasum, datacow enabled");
 466                                 else
 467                                         btrfs_info(root->fs_info,
 468                                                    "setting datasum");
 469                         }
 470                         btrfs_clear_opt(info->mount_opt, NODATACOW);
 471                         btrfs_clear_opt(info->mount_opt, NODATASUM);
 472                         break;
 473                 case Opt_nodatacow:
 474                         if (!btrfs_test_opt(info, NODATACOW)) {
 475                                 if (!btrfs_test_opt(info, COMPRESS) ||
 476                                     !btrfs_test_opt(info, FORCE_COMPRESS)) {
 477                                         btrfs_info(root->fs_info,
 478                                                    "setting nodatacow, compression disabled");
 479                                 } else {
 480                                         btrfs_info(root->fs_info,
 481                                                    "setting nodatacow");
 482                                 }
 483                         }
 484                         btrfs_clear_opt(info->mount_opt, COMPRESS);
 485                         btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 486                         btrfs_set_opt(info->mount_opt, NODATACOW);
 487                         btrfs_set_opt(info->mount_opt, NODATASUM);
 488                         break;
 489                 case Opt_datacow:
 490                         btrfs_clear_and_info(info, NODATACOW,
 491                                              "setting datacow");
 492                         break;
 493                 case Opt_compress_force:
 494                 case Opt_compress_force_type:
 495                         compress_force = true;
 496                         /* Fallthrough */
 497                 case Opt_compress:
 498                 case Opt_compress_type:
 499                         saved_compress_type = btrfs_test_opt(info,
 500                                                              COMPRESS) ?
 501                                 info->compress_type : BTRFS_COMPRESS_NONE;
 502                         saved_compress_force =
 503                                 btrfs_test_opt(info, FORCE_COMPRESS);
 504                         if (token == Opt_compress ||
 505                             token == Opt_compress_force ||
 506                             strcmp(args[0].from, "zlib") == 0) {
 507                                 compress_type = "zlib";
 508                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 509                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 510                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 511                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 512                                 no_compress = 0;
 513                         } else if (strcmp(args[0].from, "lzo") == 0) {
 514                                 compress_type = "lzo";
 515                                 info->compress_type = BTRFS_COMPRESS_LZO;
 516                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 517                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 518                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 519                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
 520                                 no_compress = 0;
 521                         } else if (strncmp(args[0].from, "no", 2) == 0) {
 522                                 compress_type = "no";
 523                                 btrfs_clear_opt(info->mount_opt, COMPRESS);
 524                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 525                                 compress_force = false;
 526                                 no_compress++;
 527                         } else {
 528                                 ret = -EINVAL;
 529                                 goto out;
 530                         }
 531
 532                         if (compress_force) {
 533                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 534                         } else {
 535                                 /*
 536                                  * If we remount from compress-force=xxx to
 537                                  * compress=xxx, we need clear FORCE_COMPRESS
 538                                  * flag, otherwise, there is no way for users
 539                                  * to disable forcible compression separately.
 540                                  */
 541                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 542                         }
 543                         if ((btrfs_test_opt(info, COMPRESS) &&
 544                              (info->compress_type != saved_compress_type ||
 545                               compress_force != saved_compress_force)) ||
 546                             (!btrfs_test_opt(info, COMPRESS) &&
 547                              no_compress == 1)) {
 548                                 btrfs_info(root->fs_info,
 549                                            "%s %s compression",
 550                                            (compress_force) ? "force" : "use",
 551                                            compress_type);
 552                         }
 553                         compress_force = false;
 554                         break;
 555                 case Opt_ssd:
 556                         btrfs_set_and_info(info, SSD,
 557                                            "use ssd allocation scheme");
 558                         break;
 559                 case Opt_ssd_spread:
 560                         btrfs_set_and_info(info, SSD_SPREAD,
 561                                            "use spread ssd allocation scheme");
 562                         btrfs_set_opt(info->mount_opt, SSD);
 563                         break;
 564                 case Opt_nossd:
 565                         btrfs_set_and_info(info, NOSSD,
 566                                              "not using ssd allocation scheme");
 567                         btrfs_clear_opt(info->mount_opt, SSD);
 568                         break;
 569                 case Opt_barrier:
 570                         btrfs_clear_and_info(info, NOBARRIER,
 571                                              "turning on barriers");
 572                         break;
 573                 case Opt_nobarrier:
 574                         btrfs_set_and_info(info, NOBARRIER,
 575                                            "turning off barriers");
 576                         break;
 577                 case Opt_thread_pool:
 578                         ret = match_int(&args[0], &intarg);
 579                         if (ret) {
 580                                 goto out;
 581                         } else if (intarg > 0) {
 582                                 info->thread_pool_size = intarg;
 583                         } else {
 584                                 ret = -EINVAL;
 585                                 goto out;
 586                         }
 587                         break;
 588                 case Opt_max_inline:
 589                         num = match_strdup(&args[0]);
 590                         if (num) {
 591                                 info->max_inline = memparse(num, NULL);
 592                                 kfree(num);
 593
 594                                 if (info->max_inline) {
 595                                         info->max_inline = min_t(u64,
 596                                                 info->max_inline,
 597                                                 root->sectorsize);
 598                                 }
 599                                 btrfs_info(root->fs_info, "max_inline at %llu",
 600                                         info->max_inline);
 601                         } else {
 602                                 ret = -ENOMEM;
 603                                 goto out;
 604                         }
 605                         break;
 606                 case Opt_alloc_start:
 607                         num = match_strdup(&args[0]);
 608                         if (num) {
 609                                 mutex_lock(&info->chunk_mutex);
 610                                 info->alloc_start = memparse(num, NULL);
 611                                 mutex_unlock(&info->chunk_mutex);
 612                                 kfree(num);
 613                                 btrfs_info(root->fs_info,
 614                                            "allocations start at %llu",
 615                                            info->alloc_start);
 616                         } else {
 617                                 ret = -ENOMEM;
 618                                 goto out;
 619                         }
 620                         break;
 621                 case Opt_acl:
 622 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 623                         root->fs_info->sb->s_flags |= MS_POSIXACL;
 624                         break;
 625 #else
 626                         btrfs_err(root->fs_info,
 627                                 "support for ACL not compiled in!");
 628                         ret = -EINVAL;
 629                         goto out;
 630 #endif
 631                 case Opt_noacl:
 632                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 633                         break;
 634                 case Opt_notreelog:
 635                         btrfs_set_and_info(info, NOTREELOG,
 636                                            "disabling tree log");
 637                         break;
 638                 case Opt_treelog:
 639                         btrfs_clear_and_info(info, NOTREELOG,
 640                                              "enabling tree log");
 641                         break;
 642                 case Opt_norecovery:
 643                 case Opt_nologreplay:
 644                         btrfs_set_and_info(info, NOLOGREPLAY,
 645                                            "disabling log replay at mount time");
 646                         break;
 647                 case Opt_flushoncommit:
 648                         btrfs_set_and_info(info, FLUSHONCOMMIT,
 649                                            "turning on flush-on-commit");
 650                         break;
 651                 case Opt_noflushoncommit:
 652                         btrfs_clear_and_info(info, FLUSHONCOMMIT,
 653                                              "turning off flush-on-commit");
 654                         break;
 655                 case Opt_ratio:
 656                         ret = match_int(&args[0], &intarg);
 657                         if (ret) {
 658                                 goto out;
 659                         } else if (intarg >= 0) {
 660                                 info->metadata_ratio = intarg;
 661                                 btrfs_info(root->fs_info, "metadata ratio %d",
 662                                        info->metadata_ratio);
 663                         } else {
 664                                 ret = -EINVAL;
 665                                 goto out;
 666                         }
 667                         break;
 668                 case Opt_discard:
 669                         btrfs_set_and_info(info, DISCARD,
 670                                            "turning on discard");
 671                         break;
 672                 case Opt_nodiscard:
 673                         btrfs_clear_and_info(info, DISCARD,
 674                                              "turning off discard");
 675                         break;
 676                 case Opt_space_cache:
 677                 case Opt_space_cache_version:
 678                         if (token == Opt_space_cache ||
 679                             strcmp(args[0].from, "v1") == 0) {
 680                                 btrfs_clear_opt(root->fs_info->mount_opt,
 681                                                 FREE_SPACE_TREE);
 682                                 btrfs_set_and_info(info, SPACE_CACHE,
 683                                                    "enabling disk space caching");
 684                         } else if (strcmp(args[0].from, "v2") == 0) {
 685                                 btrfs_clear_opt(root->fs_info->mount_opt,
 686                                                 SPACE_CACHE);
 687                                 btrfs_set_and_info(info,
 688                                                    FREE_SPACE_TREE,
 689                                                    "enabling free space tree");
 690                         } else {
 691                                 ret = -EINVAL;
 692                                 goto out;
 693                         }
 694                         break;
 695                 case Opt_rescan_uuid_tree:
 696                         btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
 697                         break;
 698                 case Opt_no_space_cache:
 699                         if (btrfs_test_opt(info, SPACE_CACHE)) {
 700                                 btrfs_clear_and_info(info,
 701                                                      SPACE_CACHE,
 702                                                      "disabling disk space caching");
 703                         }
 704                         if (btrfs_test_opt(info, FREE_SPACE_TREE)) {
 705                                 btrfs_clear_and_info(info,
 706                                                      FREE_SPACE_TREE,
 707                                                      "disabling free space tree");
 708                         }
 709                         break;
 710                 case Opt_inode_cache:
 711                         btrfs_set_pending_and_info(info, INODE_MAP_CACHE,
 712                                            "enabling inode map caching");
 713                         break;
 714                 case Opt_noinode_cache:
 715                         btrfs_clear_pending_and_info(info, INODE_MAP_CACHE,
 716                                              "disabling inode map caching");
 717                         break;
 718                 case Opt_clear_cache:
 719                         btrfs_set_and_info(info, CLEAR_CACHE,
 720                                            "force clearing of disk cache");
 721                         break;
 722                 case Opt_user_subvol_rm_allowed:
 723                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 724                         break;
 725                 case Opt_enospc_debug:
 726                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 727                         break;
 728                 case Opt_noenospc_debug:
 729                         btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
 730                         break;
 731                 case Opt_defrag:
 732                         btrfs_set_and_info(info, AUTO_DEFRAG,
 733                                            "enabling auto defrag");
 734                         break;
 735                 case Opt_nodefrag:
 736                         btrfs_clear_and_info(info, AUTO_DEFRAG,
 737                                              "disabling auto defrag");
 738                         break;
 739                 case Opt_recovery:
 740                         btrfs_warn(root->fs_info,
 741                                    "'recovery' is deprecated, use 'usebackuproot' instead");
 742                 case Opt_usebackuproot:
 743                         btrfs_info(root->fs_info,
 744                                    "trying to use backup root at mount time");
 745                         btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
 746                         break;
 747                 case Opt_skip_balance:
 748                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 749                         break;
 750 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 751                 case Opt_check_integrity_including_extent_data:
 752                         btrfs_info(root->fs_info,
 753                                    "enabling check integrity including extent data");
 754                         btrfs_set_opt(info->mount_opt,
 755                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 756                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 757                         break;
 758                 case Opt_check_integrity:
 759                         btrfs_info(root->fs_info, "enabling check integrity");
 760                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 761                         break;
 762                 case Opt_check_integrity_print_mask:
 763                         ret = match_int(&args[0], &intarg);
 764                         if (ret) {
 765                                 goto out;
 766                         } else if (intarg >= 0) {
 767                                 info->check_integrity_print_mask = intarg;
 768                                 btrfs_info(root->fs_info,
 769                                            "check_integrity_print_mask 0x%x",
 770                                            info->check_integrity_print_mask);
 771                         } else {
 772                                 ret = -EINVAL;
 773                                 goto out;
 774                         }
 775                         break;
 776 #else
 777                 case Opt_check_integrity_including_extent_data:
 778                 case Opt_check_integrity:
 779                 case Opt_check_integrity_print_mask:
 780                         btrfs_err(root->fs_info,
 781                                 "support for check_integrity* not compiled in!");
 782                         ret = -EINVAL;
 783                         goto out;
 784 #endif
 785                 case Opt_fatal_errors:
 786                         if (strcmp(args[0].from, "panic") == 0)
 787                                 btrfs_set_opt(info->mount_opt,
 788                                               PANIC_ON_FATAL_ERROR);
 789                         else if (strcmp(args[0].from, "bug") == 0)
 790                                 btrfs_clear_opt(info->mount_opt,
 791                                               PANIC_ON_FATAL_ERROR);
 792                         else {
 793                                 ret = -EINVAL;
 794                                 goto out;
 795                         }
 796                         break;
 797                 case Opt_commit_interval:
 798                         intarg = 0;
 799                         ret = match_int(&args[0], &intarg);
 800                         if (ret < 0) {
 801                                 btrfs_err(root->fs_info,
 802                                           "invalid commit interval");
 803                                 ret = -EINVAL;
 804                                 goto out;
 805                         }
 806                         if (intarg > 0) {
 807                                 if (intarg > 300) {
 808                                         btrfs_warn(root->fs_info,
 809                                                 "excessive commit interval %d",
 810                                                 intarg);
 811                                 }
 812                                 info->commit_interval = intarg;
 813                         } else {
 814                                 btrfs_info(root->fs_info,
 815                                            "using default commit interval %ds",
 816                                            BTRFS_DEFAULT_COMMIT_INTERVAL);
 817                                 info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
 818                         }
 819                         break;
 820 #ifdef CONFIG_BTRFS_DEBUG
 821                 case Opt_fragment_all:
 822                         btrfs_info(root->fs_info, "fragmenting all space");
 823                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 824                         btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
 825                         break;
 826                 case Opt_fragment_metadata:
 827                         btrfs_info(root->fs_info, "fragmenting metadata");
 828                         btrfs_set_opt(info->mount_opt,
 829                                       FRAGMENT_METADATA);
 830                         break;
 831                 case Opt_fragment_data:
 832                         btrfs_info(root->fs_info, "fragmenting data");
 833                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 834                         break;
 835 #endif
 836                 case Opt_err:
 837                         btrfs_info(root->fs_info,
 838                                    "unrecognized mount option '%s'", p);
 839                         ret = -EINVAL;
 840                         goto out;
 841                 default:
 842                         break;
 843                 }
 844         }
 845 check:
 846         /*
 847          * Extra check for current option against current flag
 848          */
 849         if (btrfs_test_opt(info, NOLOGREPLAY) && !(new_flags & MS_RDONLY)) {
 850                 btrfs_err(root->fs_info,
 851                           "nologreplay must be used with ro mount option");
 852                 ret = -EINVAL;
 853         }
 854 out:
 855         if (btrfs_fs_compat_ro(root->fs_info, FREE_SPACE_TREE) &&
 856             !btrfs_test_opt(info, FREE_SPACE_TREE) &&
 857             !btrfs_test_opt(info, CLEAR_CACHE)) {
 858                 btrfs_err(root->fs_info, "cannot disable free space tree");
 859                 ret = -EINVAL;
 860
 861         }
 862         if (!ret && btrfs_test_opt(info, SPACE_CACHE))
 863                 btrfs_info(root->fs_info, "disk space caching is enabled");
 864         if (!ret && btrfs_test_opt(info, FREE_SPACE_TREE))
 865                 btrfs_info(root->fs_info, "using free space tree");
 866         kfree(orig);
 867         return ret;
 868 }
 869
 870 /*
 871  * Parse mount options that are required early in the mount process.
 872  *
 873  * All other options will be parsed on much later in the mount process and
 874  * only when we need to allocate a new super block.
 875  */
 876 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 877                 void *holder, char **subvol_name, u64 *subvol_objectid,
 878                 struct btrfs_fs_devices **fs_devices)
 879 {
 880         substring_t args[MAX_OPT_ARGS];
 881         char *device_name, *opts, *orig, *p;
 882         char *num = NULL;
 883         int error = 0;
 884
 885         if (!options)
 886                 return 0;
 887
 888         /*
 889          * strsep changes the string, duplicate it because parse_options
 890          * gets called twice
 891          */
 892         opts = kstrdup(options, GFP_KERNEL);
 893         if (!opts)
 894                 return -ENOMEM;
 895         orig = opts;
 896
 897         while ((p = strsep(&opts, ",")) != NULL) {
 898                 int token;
 899                 if (!*p)
 900                         continue;
 901
 902                 token = match_token(p, tokens, args);
 903                 switch (token) {
 904                 case Opt_subvol:
 905                         kfree(*subvol_name);
 906                         *subvol_name = match_strdup(&args[0]);
 907                         if (!*subvol_name) {
 908                                 error = -ENOMEM;
 909                                 goto out;
 910                         }
 911                         break;
 912                 case Opt_subvolid:
 913                         num = match_strdup(&args[0]);
 914                         if (num) {
 915                                 *subvol_objectid = memparse(num, NULL);
 916                                 kfree(num);
 917                                 /* we want the original fs_tree */
 918                                 if (!*subvol_objectid)
 919                                         *subvol_objectid =
 920                                                 BTRFS_FS_TREE_OBJECTID;
 921                         } else {
 922                                 error = -EINVAL;
 923                                 goto out;
 924                         }
 925                         break;
 926                 case Opt_subvolrootid:
 927                         pr_warn("BTRFS: 'subvolrootid' mount option is deprecated and has no effect\n");
 928                         break;
 929                 case Opt_device:
 930                         device_name = match_strdup(&args[0]);
 931                         if (!device_name) {
 932                                 error = -ENOMEM;
 933                                 goto out;
 934                         }
 935                         error = btrfs_scan_one_device(device_name,
 936                                         flags, holder, fs_devices);
 937                         kfree(device_name);
 938                         if (error)
 939                                 goto out;
 940                         break;
 941                 default:
 942                         break;
 943                 }
 944         }
 945
 946 out:
 947         kfree(orig);
 948         return error;
 949 }
 950
 951 static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 952                                            u64 subvol_objectid)
 953 {
 954         struct btrfs_root *root = fs_info->tree_root;
 955         struct btrfs_root *fs_root;
 956         struct btrfs_root_ref *root_ref;
 957         struct btrfs_inode_ref *inode_ref;
 958         struct btrfs_key key;
 959         struct btrfs_path *path = NULL;
 960         char *name = NULL, *ptr;
 961         u64 dirid;
 962         int len;
 963         int ret;
 964
 965         path = btrfs_alloc_path();
 966         if (!path) {
 967                 ret = -ENOMEM;
 968                 goto err;
 969         }
 970         path->leave_spinning = 1;
 971
 972         name = kmalloc(PATH_MAX, GFP_NOFS);
 973         if (!name) {
 974                 ret = -ENOMEM;
 975                 goto err;
 976         }
 977         ptr = name + PATH_MAX - 1;
 978         ptr[0] = '\0';
 979
 980         /*
 981          * Walk up the subvolume trees in the tree of tree roots by root
 982          * backrefs until we hit the top-level subvolume.
 983          */
 984         while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
 985                 key.objectid = subvol_objectid;
 986                 key.type = BTRFS_ROOT_BACKREF_KEY;
 987                 key.offset = (u64)-1;
 988
 989                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 990                 if (ret < 0) {
 991                         goto err;
 992                 } else if (ret > 0) {
 993                         ret = btrfs_previous_item(root, path, subvol_objectid,
 994                                                   BTRFS_ROOT_BACKREF_KEY);
 995                         if (ret < 0) {
 996                                 goto err;
 997                         } else if (ret > 0) {
 998                                 ret = -ENOENT;
 999                                 goto err;
1000                         }
1001                 }
1002
1003                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1004                 subvol_objectid = key.offset;
1005
1006                 root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1007                                           struct btrfs_root_ref);
1008                 len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
1009                 ptr -= len + 1;
1010                 if (ptr < name) {
1011                         ret = -ENAMETOOLONG;
1012                         goto err;
1013                 }
1014                 read_extent_buffer(path->nodes[0], ptr + 1,
1015                                    (unsigned long)(root_ref + 1), len);
1016                 ptr[0] = '/';
1017                 dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
1018                 btrfs_release_path(path);
1019
1020                 key.objectid = subvol_objectid;
1021                 key.type = BTRFS_ROOT_ITEM_KEY;
1022                 key.offset = (u64)-1;
1023                 fs_root = btrfs_read_fs_root_no_name(fs_info, &key);
1024                 if (IS_ERR(fs_root)) {
1025                         ret = PTR_ERR(fs_root);
1026                         goto err;
1027                 }
1028
1029                 /*
1030                  * Walk up the filesystem tree by inode refs until we hit the
1031                  * root directory.
1032                  */
1033                 while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
1034                         key.objectid = dirid;
1035                         key.type = BTRFS_INODE_REF_KEY;
1036                         key.offset = (u64)-1;
1037
1038                         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1039                         if (ret < 0) {
1040                                 goto err;
1041                         } else if (ret > 0) {
1042                                 ret = btrfs_previous_item(fs_root, path, dirid,
1043                                                           BTRFS_INODE_REF_KEY);
1044                                 if (ret < 0) {
1045                                         goto err;
1046                                 } else if (ret > 0) {
1047                                         ret = -ENOENT;
1048                                         goto err;
1049                                 }
1050                         }
1051
1052                         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1053                         dirid = key.offset;
1054
1055                         inode_ref = btrfs_item_ptr(path->nodes[0],
1056                                                    path->slots[0],
1057                                                    struct btrfs_inode_ref);
1058                         len = btrfs_inode_ref_name_len(path->nodes[0],
1059                                                        inode_ref);
1060                         ptr -= len + 1;
1061                         if (ptr < name) {
1062                                 ret = -ENAMETOOLONG;
1063                                 goto err;
1064                         }
1065                         read_extent_buffer(path->nodes[0], ptr + 1,
1066                                            (unsigned long)(inode_ref + 1), len);
1067                         ptr[0] = '/';
1068                         btrfs_release_path(path);
1069                 }
1070         }
1071
1072         btrfs_free_path(path);
1073         if (ptr == name + PATH_MAX - 1) {
1074                 name[0] = '/';
1075                 name[1] = '\0';
1076         } else {
1077                 memmove(name, ptr, name + PATH_MAX - ptr);
1078         }
1079         return name;
1080
1081 err:
1082         btrfs_free_path(path);
1083         kfree(name);
1084         return ERR_PTR(ret);
1085 }
1086
1087 static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
1088 {
1089         struct btrfs_root *root = fs_info->tree_root;
1090         struct btrfs_dir_item *di;
1091         struct btrfs_path *path;
1092         struct btrfs_key location;
1093         u64 dir_id;
1094
1095         path = btrfs_alloc_path();
1096         if (!path)
1097                 return -ENOMEM;
1098         path->leave_spinning = 1;
1099
1100         /*
1101          * Find the "default" dir item which points to the root item that we
1102          * will mount by default if we haven't been given a specific subvolume
1103          * to mount.
1104          */
1105         dir_id = btrfs_super_root_dir(fs_info->super_copy);
1106         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
1107         if (IS_ERR(di)) {
1108                 btrfs_free_path(path);
1109                 return PTR_ERR(di);
1110         }
1111         if (!di) {
1112                 /*
1113                  * Ok the default dir item isn't there.  This is weird since
1114                  * it's always been there, but don't freak out, just try and
1115                  * mount the top-level subvolume.
1116                  */
1117                 btrfs_free_path(path);
1118                 *objectid = BTRFS_FS_TREE_OBJECTID;
1119                 return 0;
1120         }
1121
1122         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
1123         btrfs_free_path(path);
1124         *objectid = location.objectid;
1125         return 0;
1126 }
1127
1128 static int btrfs_fill_super(struct super_block *sb,
1129                             struct btrfs_fs_devices *fs_devices,
1130                             void *data, int silent)
1131 {
1132         struct inode *inode;
1133         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1134         struct btrfs_key key;
1135         int err;
1136
1137         sb->s_maxbytes = MAX_LFS_FILESIZE;
1138         sb->s_magic = BTRFS_SUPER_MAGIC;
1139         sb->s_op = &btrfs_super_ops;
1140         sb->s_d_op = &btrfs_dentry_operations;
1141         sb->s_export_op = &btrfs_export_ops;
1142         sb->s_xattr = btrfs_xattr_handlers;
1143         sb->s_time_gran = 1;
1144 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
1145         sb->s_flags |= MS_POSIXACL;
1146 #endif
1147         sb->s_flags |= MS_I_VERSION;
1148         sb->s_iflags |= SB_I_CGROUPWB;
1149         err = open_ctree(sb, fs_devices, (char *)data);
1150         if (err) {
1151                 btrfs_err(fs_info, "open_ctree failed");
1152                 return err;
1153         }
1154
1155         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
1156         key.type = BTRFS_INODE_ITEM_KEY;
1157         key.offset = 0;
1158         inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
1159         if (IS_ERR(inode)) {
1160                 err = PTR_ERR(inode);
1161                 goto fail_close;
1162         }
1163
1164         sb->s_root = d_make_root(inode);
1165         if (!sb->s_root) {
1166                 err = -ENOMEM;
1167                 goto fail_close;
1168         }
1169
1170         save_mount_options(sb, data);
1171         cleancache_init_fs(sb);
1172         sb->s_flags |= MS_ACTIVE;
1173         return 0;
1174
1175 fail_close:
1176         close_ctree(fs_info->tree_root);
1177         return err;
1178 }
1179
1180 int btrfs_sync_fs(struct super_block *sb, int wait)
1181 {
1182         struct btrfs_trans_handle *trans;
1183         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1184         struct btrfs_root *root = fs_info->tree_root;
1185
1186         trace_btrfs_sync_fs(fs_info, wait);
1187
1188         if (!wait) {
1189                 filemap_flush(fs_info->btree_inode->i_mapping);
1190                 return 0;
1191         }
1192
1193         btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
1194
1195         trans = btrfs_attach_transaction_barrier(root);
1196         if (IS_ERR(trans)) {
1197                 /* no transaction, don't bother */
1198                 if (PTR_ERR(trans) == -ENOENT) {
1199                         /*
1200                          * Exit unless we have some pending changes
1201                          * that need to go through commit
1202                          */
1203                         if (fs_info->pending_changes == 0)
1204                                 return 0;
1205                         /*
1206                          * A non-blocking test if the fs is frozen. We must not
1207                          * start a new transaction here otherwise a deadlock
1208                          * happens. The pending operations are delayed to the
1209                          * next commit after thawing.
1210                          */
1211                         if (__sb_start_write(sb, SB_FREEZE_WRITE, false))
1212                                 __sb_end_write(sb, SB_FREEZE_WRITE);
1213                         else
1214                                 return 0;
1215                         trans = btrfs_start_transaction(root, 0);
1216                 }
1217                 if (IS_ERR(trans))
1218                         return PTR_ERR(trans);
1219         }
1220         return btrfs_commit_transaction(trans, root);
1221 }
1222
1223 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1224 {
1225         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1226         struct btrfs_root *root = info->tree_root;
1227         char *compress_type;
1228
1229         if (btrfs_test_opt(info, DEGRADED))
1230                 seq_puts(seq, ",degraded");
1231         if (btrfs_test_opt(info, NODATASUM))
1232                 seq_puts(seq, ",nodatasum");
1233         if (btrfs_test_opt(info, NODATACOW))
1234                 seq_puts(seq, ",nodatacow");
1235         if (btrfs_test_opt(info, NOBARRIER))
1236                 seq_puts(seq, ",nobarrier");
1237         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1238                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
1239         if (info->alloc_start != 0)
1240                 seq_printf(seq, ",alloc_start=%llu", info->alloc_start);
1241         if (info->thread_pool_size !=  min_t(unsigned long,
1242                                              num_online_cpus() + 2, 8))
1243                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
1244         if (btrfs_test_opt(info, COMPRESS)) {
1245                 if (info->compress_type == BTRFS_COMPRESS_ZLIB)
1246                         compress_type = "zlib";
1247                 else
1248                         compress_type = "lzo";
1249                 if (btrfs_test_opt(info, FORCE_COMPRESS))
1250                         seq_printf(seq, ",compress-force=%s", compress_type);
1251                 else
1252                         seq_printf(seq, ",compress=%s", compress_type);
1253         }
1254         if (btrfs_test_opt(info, NOSSD))
1255                 seq_puts(seq, ",nossd");
1256         if (btrfs_test_opt(info, SSD_SPREAD))
1257                 seq_puts(seq, ",ssd_spread");
1258         else if (btrfs_test_opt(info, SSD))
1259                 seq_puts(seq, ",ssd");
1260         if (btrfs_test_opt(info, NOTREELOG))
1261                 seq_puts(seq, ",notreelog");
1262         if (btrfs_test_opt(info, NOLOGREPLAY))
1263                 seq_puts(seq, ",nologreplay");
1264         if (btrfs_test_opt(info, FLUSHONCOMMIT))
1265                 seq_puts(seq, ",flushoncommit");
1266         if (btrfs_test_opt(info, DISCARD))
1267                 seq_puts(seq, ",discard");
1268         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
1269                 seq_puts(seq, ",noacl");
1270         if (btrfs_test_opt(info, SPACE_CACHE))
1271                 seq_puts(seq, ",space_cache");
1272         else if (btrfs_test_opt(info, FREE_SPACE_TREE))
1273                 seq_puts(seq, ",space_cache=v2");
1274         else
1275                 seq_puts(seq, ",nospace_cache");
1276         if (btrfs_test_opt(info, RESCAN_UUID_TREE))
1277                 seq_puts(seq, ",rescan_uuid_tree");
1278         if (btrfs_test_opt(info, CLEAR_CACHE))
1279                 seq_puts(seq, ",clear_cache");
1280         if (btrfs_test_opt(info, USER_SUBVOL_RM_ALLOWED))
1281                 seq_puts(seq, ",user_subvol_rm_allowed");
1282         if (btrfs_test_opt(info, ENOSPC_DEBUG))
1283                 seq_puts(seq, ",enospc_debug");
1284         if (btrfs_test_opt(info, AUTO_DEFRAG))
1285                 seq_puts(seq, ",autodefrag");
1286         if (btrfs_test_opt(info, INODE_MAP_CACHE))
1287                 seq_puts(seq, ",inode_cache");
1288         if (btrfs_test_opt(info, SKIP_BALANCE))
1289                 seq_puts(seq, ",skip_balance");
1290 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1291         if (btrfs_test_opt(info, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
1292                 seq_puts(seq, ",check_int_data");
1293         else if (btrfs_test_opt(info, CHECK_INTEGRITY))
1294                 seq_puts(seq, ",check_int");
1295         if (info->check_integrity_print_mask)
1296                 seq_printf(seq, ",check_int_print_mask=%d",
1297                                 info->check_integrity_print_mask);
1298 #endif
1299         if (info->metadata_ratio)
1300                 seq_printf(seq, ",metadata_ratio=%d",
1301                                 info->metadata_ratio);
1302         if (btrfs_test_opt(info, PANIC_ON_FATAL_ERROR))
1303                 seq_puts(seq, ",fatal_errors=panic");
1304         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1305                 seq_printf(seq, ",commit=%d", info->commit_interval);
1306 #ifdef CONFIG_BTRFS_DEBUG
1307         if (btrfs_test_opt(info, FRAGMENT_DATA))
1308                 seq_puts(seq, ",fragment=data");
1309         if (btrfs_test_opt(info, FRAGMENT_METADATA))
1310                 seq_puts(seq, ",fragment=metadata");
1311 #endif
1312         seq_printf(seq, ",subvolid=%llu",
1313                   BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1314         seq_puts(seq, ",subvol=");
1315         seq_dentry(seq, dentry, " \t\n\\");
1316         return 0;
1317 }
1318
1319 static int btrfs_test_super(struct super_block *s, void *data)
1320 {
1321         struct btrfs_fs_info *p = data;
1322         struct btrfs_fs_info *fs_info = btrfs_sb(s);
1323
1324         return fs_info->fs_devices == p->fs_devices;
1325 }
1326
1327 static int btrfs_set_super(struct super_block *s, void *data)
1328 {
1329         int err = set_anon_super(s, data);
1330         if (!err)
1331                 s->s_fs_info = data;
1332         return err;
1333 }
1334
1335 /*
1336  * subvolumes are identified by ino 256
1337  */
1338 static inline int is_subvolume_inode(struct inode *inode)
1339 {
1340         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1341                 return 1;
1342         return 0;
1343 }
1344
1345 /*
1346  * This will add subvolid=0 to the argument string while removing any subvol=
1347  * and subvolid= arguments to make sure we get the top-level root for path
1348  * walking to the subvol we want.
1349  */
1350 static char *setup_root_args(char *args)
1351 {
1352         char *buf, *dst, *sep;
1353
1354         if (!args)
1355                 return kstrdup("subvolid=0", GFP_NOFS);
1356
1357         /* The worst case is that we add ",subvolid=0" to the end. */
1358         buf = dst = kmalloc(strlen(args) + strlen(",subvolid=0") + 1, GFP_NOFS);
1359         if (!buf)
1360                 return NULL;
1361
1362         while (1) {
1363                 sep = strchrnul(args, ',');
1364                 if (!strstarts(args, "subvol=") &&
1365                     !strstarts(args, "subvolid=")) {
1366                         memcpy(dst, args, sep - args);
1367                         dst += sep - args;
1368                         *dst++ = ',';
1369                 }
1370                 if (*sep)
1371                         args = sep + 1;
1372                 else
1373                         break;
1374         }
1375         strcpy(dst, "subvolid=0");
1376
1377         return buf;
1378 }
1379
1380 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
1381                                    int flags, const char *device_name,
1382                                    char *data)
1383 {
1384         struct dentry *root;
1385         struct vfsmount *mnt = NULL;
1386         char *newargs;
1387         int ret;
1388
1389         newargs = setup_root_args(data);
1390         if (!newargs) {
1391                 root = ERR_PTR(-ENOMEM);
1392                 goto out;
1393         }
1394
1395         mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name, newargs);
1396         if (PTR_ERR_OR_ZERO(mnt) == -EBUSY) {
1397                 if (flags & MS_RDONLY) {
1398                         mnt = vfs_kern_mount(&btrfs_fs_type, flags & ~MS_RDONLY,
1399                                              device_name, newargs);
1400                 } else {
1401                         mnt = vfs_kern_mount(&btrfs_fs_type, flags | MS_RDONLY,
1402                                              device_name, newargs);
1403                         if (IS_ERR(mnt)) {
1404                                 root = ERR_CAST(mnt);
1405                                 mnt = NULL;
1406                                 goto out;
1407                         }
1408
1409                         down_write(&mnt->mnt_sb->s_umount);
1410                         ret = btrfs_remount(mnt->mnt_sb, &flags, NULL);
1411                         up_write(&mnt->mnt_sb->s_umount);
1412                         if (ret < 0) {
1413                                 root = ERR_PTR(ret);
1414                                 goto out;
1415                         }
1416                 }
1417         }
1418         if (IS_ERR(mnt)) {
1419                 root = ERR_CAST(mnt);
1420                 mnt = NULL;
1421                 goto out;
1422         }
1423
1424         if (!subvol_name) {
1425                 if (!subvol_objectid) {
1426                         ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
1427                                                           &subvol_objectid);
1428                         if (ret) {
1429                                 root = ERR_PTR(ret);
1430                                 goto out;
1431                         }
1432                 }
1433                 subvol_name = get_subvol_name_from_objectid(btrfs_sb(mnt->mnt_sb),
1434                                                             subvol_objectid);
1435                 if (IS_ERR(subvol_name)) {
1436                         root = ERR_CAST(subvol_name);
1437                         subvol_name = NULL;
1438                         goto out;
1439                 }
1440
1441         }
1442
1443         root = mount_subtree(mnt, subvol_name);
1444         /* mount_subtree() drops our reference on the vfsmount. */
1445         mnt = NULL;
1446
1447         if (!IS_ERR(root)) {
1448                 struct super_block *s = root->d_sb;
1449                 struct btrfs_fs_info *fs_info = btrfs_sb(s);
1450                 struct inode *root_inode = d_inode(root);
1451                 u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
1452
1453                 ret = 0;
1454                 if (!is_subvolume_inode(root_inode)) {
1455                         btrfs_err(fs_info, "'%s' is not a valid subvolume",
1456                                subvol_name);
1457                         ret = -EINVAL;
1458                 }
1459                 if (subvol_objectid && root_objectid != subvol_objectid) {
1460                         /*
1461                          * This will also catch a race condition where a
1462                          * subvolume which was passed by ID is renamed and
1463                          * another subvolume is renamed over the old location.
1464                          */
1465                         btrfs_err(fs_info,
1466                                   "subvol '%s' does not match subvolid %llu",
1467                                   subvol_name, subvol_objectid);
1468                         ret = -EINVAL;
1469                 }
1470                 if (ret) {
1471                         dput(root);
1472                         root = ERR_PTR(ret);
1473                         deactivate_locked_super(s);
1474                 }
1475         }
1476
1477 out:
1478         mntput(mnt);
1479         kfree(newargs);
1480         kfree(subvol_name);
1481         return root;
1482 }
1483
1484 static int parse_security_options(char *orig_opts,
1485                                   struct security_mnt_opts *sec_opts)
1486 {
1487         char *secdata = NULL;
1488         int ret = 0;
1489
1490         secdata = alloc_secdata();
1491         if (!secdata)
1492                 return -ENOMEM;
1493         ret = security_sb_copy_data(orig_opts, secdata);
1494         if (ret) {
1495                 free_secdata(secdata);
1496                 return ret;
1497         }
1498         ret = security_sb_parse_opts_str(secdata, sec_opts);
1499         free_secdata(secdata);
1500         return ret;
1501 }
1502
1503 static int setup_security_options(struct btrfs_fs_info *fs_info,
1504                                   struct super_block *sb,
1505                                   struct security_mnt_opts *sec_opts)
1506 {
1507         int ret = 0;
1508
1509         /*
1510          * Call security_sb_set_mnt_opts() to check whether new sec_opts
1511          * is valid.
1512          */
1513         ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
1514         if (ret)
1515                 return ret;
1516
1517 #ifdef CONFIG_SECURITY
1518         if (!fs_info->security_opts.num_mnt_opts) {
1519                 /* first time security setup, copy sec_opts to fs_info */
1520                 memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts));
1521         } else {
1522                 /*
1523                  * Since SELinux (the only one supporting security_mnt_opts)
1524                  * does NOT support changing context during remount/mount of
1525                  * the same sb, this must be the same or part of the same
1526                  * security options, just free it.
1527                  */
1528                 security_free_mnt_opts(sec_opts);
1529         }
1530 #endif
1531         return ret;
1532 }
1533
1534 /*
1535  * Find a superblock for the given device / mount point.
1536  *
1537  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
1538  *        for multiple device setup.  Make sure to keep it in sync.
1539  */
1540 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1541                 const char *device_name, void *data)
1542 {
1543         struct block_device *bdev = NULL;
1544         struct super_block *s;
1545         struct btrfs_fs_devices *fs_devices = NULL;
1546         struct btrfs_fs_info *fs_info = NULL;
1547         struct security_mnt_opts new_sec_opts;
1548         fmode_t mode = FMODE_READ;
1549         char *subvol_name = NULL;
1550         u64 subvol_objectid = 0;
1551         int error = 0;
1552
1553         if (!(flags & MS_RDONLY))
1554                 mode |= FMODE_WRITE;
1555
1556         error = btrfs_parse_early_options(data, mode, fs_type,
1557                                           &subvol_name, &subvol_objectid,
1558                                           &fs_devices);
1559         if (error) {
1560                 kfree(subvol_name);
1561                 return ERR_PTR(error);
1562         }
1563
1564         if (subvol_name || subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
1565                 /* mount_subvol() will free subvol_name. */
1566                 return mount_subvol(subvol_name, subvol_objectid, flags,
1567                                     device_name, data);
1568         }
1569
1570         security_init_mnt_opts(&new_sec_opts);
1571         if (data) {
1572                 error = parse_security_options(data, &new_sec_opts);
1573                 if (error)
1574                         return ERR_PTR(error);
1575         }
1576
1577         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1578         if (error)
1579                 goto error_sec_opts;
1580
1581         /*
1582          * Setup a dummy root and fs_info for test/set super.  This is because
1583          * we don't actually fill this stuff out until open_ctree, but we need
1584          * it for searching for existing supers, so this lets us do that and
1585          * then open_ctree will properly initialize everything later.
1586          */
1587         fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
1588         if (!fs_info) {
1589                 error = -ENOMEM;
1590                 goto error_sec_opts;
1591         }
1592
1593         fs_info->fs_devices = fs_devices;
1594
1595         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1596         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1597         security_init_mnt_opts(&fs_info->security_opts);
1598         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1599                 error = -ENOMEM;
1600                 goto error_fs_info;
1601         }
1602
1603         error = btrfs_open_devices(fs_devices, mode, fs_type);
1604         if (error)
1605                 goto error_fs_info;
1606
1607         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
1608                 error = -EACCES;
1609                 goto error_close_devices;
1610         }
1611
1612         bdev = fs_devices->latest_bdev;
1613         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | MS_NOSEC,
1614                  fs_info);
1615         if (IS_ERR(s)) {
1616                 error = PTR_ERR(s);
1617                 goto error_close_devices;
1618         }
1619
1620         if (s->s_root) {
1621                 btrfs_close_devices(fs_devices);
1622                 free_fs_info(fs_info);
1623                 if ((flags ^ s->s_flags) & MS_RDONLY)
1624                         error = -EBUSY;
1625         } else {
1626                 snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
1627                 btrfs_sb(s)->bdev_holder = fs_type;
1628                 error = btrfs_fill_super(s, fs_devices, data,
1629                                          flags & MS_SILENT ? 1 : 0);
1630         }
1631         if (error) {
1632                 deactivate_locked_super(s);
1633                 goto error_sec_opts;
1634         }
1635
1636         fs_info = btrfs_sb(s);
1637         error = setup_security_options(fs_info, s, &new_sec_opts);
1638         if (error) {
1639                 deactivate_locked_super(s);
1640                 goto error_sec_opts;
1641         }
1642
1643         return dget(s->s_root);
1644
1645 error_close_devices:
1646         btrfs_close_devices(fs_devices);
1647 error_fs_info:
1648         free_fs_info(fs_info);
1649 error_sec_opts:
1650         security_free_mnt_opts(&new_sec_opts);
1651         return ERR_PTR(error);
1652 }
1653
1654 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1655                                      int new_pool_size, int old_pool_size)
1656 {
1657         if (new_pool_size == old_pool_size)
1658                 return;
1659
1660         fs_info->thread_pool_size = new_pool_size;
1661
1662         btrfs_info(fs_info, "resize thread pool %d -> %d",
1663                old_pool_size, new_pool_size);
1664
1665         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1666         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1667         btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);
1668         btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1669         btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
1670         btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
1671         btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
1672                                 new_pool_size);
1673         btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1674         btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1675         btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1676         btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
1677         btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
1678                                 new_pool_size);
1679 }
1680
1681 static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
1682 {
1683         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1684 }
1685
1686 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1687                                        unsigned long old_opts, int flags)
1688 {
1689         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1690             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1691              (flags & MS_RDONLY))) {
1692                 /* wait for any defraggers to finish */
1693                 wait_event(fs_info->transaction_wait,
1694                            (atomic_read(&fs_info->defrag_running) == 0));
1695                 if (flags & MS_RDONLY)
1696                         sync_filesystem(fs_info->sb);
1697         }
1698 }
1699
1700 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1701                                          unsigned long old_opts)
1702 {
1703         /*
1704          * We need to cleanup all defragable inodes if the autodefragment is
1705          * close or the filesystem is read only.
1706          */
1707         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1708             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1709              (fs_info->sb->s_flags & MS_RDONLY))) {
1710                 btrfs_cleanup_defrag_inodes(fs_info);
1711         }
1712
1713         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1714 }
1715
1716 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1717 {
1718         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1719         struct btrfs_root *root = fs_info->tree_root;
1720         unsigned old_flags = sb->s_flags;
1721         unsigned long old_opts = fs_info->mount_opt;
1722         unsigned long old_compress_type = fs_info->compress_type;
1723         u64 old_max_inline = fs_info->max_inline;
1724         u64 old_alloc_start = fs_info->alloc_start;
1725         int old_thread_pool_size = fs_info->thread_pool_size;
1726         unsigned int old_metadata_ratio = fs_info->metadata_ratio;
1727         int ret;
1728
1729         sync_filesystem(sb);
1730         btrfs_remount_prepare(fs_info);
1731
1732         if (data) {
1733                 struct security_mnt_opts new_sec_opts;
1734
1735                 security_init_mnt_opts(&new_sec_opts);
1736                 ret = parse_security_options(data, &new_sec_opts);
1737                 if (ret)
1738                         goto restore;
1739                 ret = setup_security_options(fs_info, sb,
1740                                              &new_sec_opts);
1741                 if (ret) {
1742                         security_free_mnt_opts(&new_sec_opts);
1743                         goto restore;
1744                 }
1745         }
1746
1747         ret = btrfs_parse_options(root, data, *flags);
1748         if (ret) {
1749                 ret = -EINVAL;
1750                 goto restore;
1751         }
1752
1753         btrfs_remount_begin(fs_info, old_opts, *flags);
1754         btrfs_resize_thread_pool(fs_info,
1755                 fs_info->thread_pool_size, old_thread_pool_size);
1756
1757         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1758                 goto out;
1759
1760         if (*flags & MS_RDONLY) {
1761                 /*
1762                  * this also happens on 'umount -rf' or on shutdown, when
1763                  * the filesystem is busy.
1764                  */
1765                 cancel_work_sync(&fs_info->async_reclaim_work);
1766
1767                 /* wait for the uuid_scan task to finish */
1768                 down(&fs_info->uuid_tree_rescan_sem);
1769                 /* avoid complains from lockdep et al. */
1770                 up(&fs_info->uuid_tree_rescan_sem);
1771
1772                 sb->s_flags |= MS_RDONLY;
1773
1774                 /*
1775                  * Setting MS_RDONLY will put the cleaner thread to
1776                  * sleep at the next loop if it's already active.
1777                  * If it's already asleep, we'll leave unused block
1778                  * groups on disk until we're mounted read-write again
1779                  * unless we clean them up here.
1780                  */
1781                 btrfs_delete_unused_bgs(fs_info);
1782
1783                 btrfs_dev_replace_suspend_for_unmount(fs_info);
1784                 btrfs_scrub_cancel(fs_info);
1785                 btrfs_pause_balance(fs_info);
1786
1787                 ret = btrfs_commit_super(root);
1788                 if (ret)
1789                         goto restore;
1790         } else {
1791                 if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
1792                         btrfs_err(fs_info,
1793                                 "Remounting read-write after error is not allowed");
1794                         ret = -EINVAL;
1795                         goto restore;
1796                 }
1797                 if (fs_info->fs_devices->rw_devices == 0) {
1798                         ret = -EACCES;
1799                         goto restore;
1800                 }
1801
1802                 if (fs_info->fs_devices->missing_devices >
1803                      fs_info->num_tolerated_disk_barrier_failures &&
1804                     !(*flags & MS_RDONLY)) {
1805                         btrfs_warn(fs_info,
1806                                 "too many missing devices, writeable remount is not allowed");
1807                         ret = -EACCES;
1808                         goto restore;
1809                 }
1810
1811                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1812                         ret = -EINVAL;
1813                         goto restore;
1814                 }
1815
1816                 ret = btrfs_cleanup_fs_roots(fs_info);
1817                 if (ret)
1818                         goto restore;
1819
1820                 /* recover relocation */
1821                 mutex_lock(&fs_info->cleaner_mutex);
1822                 ret = btrfs_recover_relocation(root);
1823                 mutex_unlock(&fs_info->cleaner_mutex);
1824                 if (ret)
1825                         goto restore;
1826
1827                 ret = btrfs_resume_balance_async(fs_info);
1828                 if (ret)
1829                         goto restore;
1830
1831                 ret = btrfs_resume_dev_replace_async(fs_info);
1832                 if (ret) {
1833                         btrfs_warn(fs_info, "failed to resume dev_replace");
1834                         goto restore;
1835                 }
1836
1837                 if (!fs_info->uuid_root) {
1838                         btrfs_info(fs_info, "creating UUID tree");
1839                         ret = btrfs_create_uuid_tree(fs_info);
1840                         if (ret) {
1841                                 btrfs_warn(fs_info,
1842                                            "failed to create the UUID tree %d",
1843                                            ret);
1844                                 goto restore;
1845                         }
1846                 }
1847                 sb->s_flags &= ~MS_RDONLY;
1848
1849                 set_bit(BTRFS_FS_OPEN, &fs_info->flags);
1850         }
1851 out:
1852         wake_up_process(fs_info->transaction_kthread);
1853         btrfs_remount_cleanup(fs_info, old_opts);
1854         return 0;
1855
1856 restore:
1857         /* We've hit an error - don't reset MS_RDONLY */
1858         if (sb->s_flags & MS_RDONLY)
1859                 old_flags |= MS_RDONLY;
1860         sb->s_flags = old_flags;
1861         fs_info->mount_opt = old_opts;
1862         fs_info->compress_type = old_compress_type;
1863         fs_info->max_inline = old_max_inline;
1864         mutex_lock(&fs_info->chunk_mutex);
1865         fs_info->alloc_start = old_alloc_start;
1866         mutex_unlock(&fs_info->chunk_mutex);
1867         btrfs_resize_thread_pool(fs_info,
1868                 old_thread_pool_size, fs_info->thread_pool_size);
1869         fs_info->metadata_ratio = old_metadata_ratio;
1870         btrfs_remount_cleanup(fs_info, old_opts);
1871         return ret;
1872 }
1873
1874 /* Used to sort the devices by max_avail(descending sort) */
1875 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1876                                        const void *dev_info2)
1877 {
1878         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1879             ((struct btrfs_device_info *)dev_info2)->max_avail)
1880                 return -1;
1881         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1882                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1883                 return 1;
1884         else
1885         return 0;
1886 }
1887
1888 /*
1889  * sort the devices by max_avail, in which max free extent size of each device
1890  * is stored.(Descending Sort)
1891  */
1892 static inline void btrfs_descending_sort_devices(
1893                                         struct btrfs_device_info *devices,
1894                                         size_t nr_devices)
1895 {
1896         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1897              btrfs_cmp_device_free_bytes, NULL);
1898 }
1899
1900 /*
1901  * The helper to calc the free space on the devices that can be used to store
1902  * file data.
1903  */
1904 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
1905 {
1906         struct btrfs_fs_info *fs_info = root->fs_info;
1907         struct btrfs_device_info *devices_info;
1908         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1909         struct btrfs_device *device;
1910         u64 skip_space;
1911         u64 type;
1912         u64 avail_space;
1913         u64 used_space;
1914         u64 min_stripe_size;
1915         int min_stripes = 1, num_stripes = 1;
1916         int i = 0, nr_devices;
1917         int ret;
1918
1919         /*
1920          * We aren't under the device list lock, so this is racy-ish, but good
1921          * enough for our purposes.
1922          */
1923         nr_devices = fs_info->fs_devices->open_devices;
1924         if (!nr_devices) {
1925                 smp_mb();
1926                 nr_devices = fs_info->fs_devices->open_devices;
1927                 ASSERT(nr_devices);
1928                 if (!nr_devices) {
1929                         *free_bytes = 0;
1930                         return 0;
1931                 }
1932         }
1933
1934         devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
1935                                GFP_NOFS);
1936         if (!devices_info)
1937                 return -ENOMEM;
1938
1939         /* calc min stripe number for data space allocation */
1940         type = btrfs_get_alloc_profile(root, 1);
1941         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1942                 min_stripes = 2;
1943                 num_stripes = nr_devices;
1944         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1945                 min_stripes = 2;
1946                 num_stripes = 2;
1947         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1948                 min_stripes = 4;
1949                 num_stripes = 4;
1950         }
1951
1952         if (type & BTRFS_BLOCK_GROUP_DUP)
1953                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1954         else
1955                 min_stripe_size = BTRFS_STRIPE_LEN;
1956
1957         if (fs_info->alloc_start)
1958                 mutex_lock(&fs_devices->device_list_mutex);
1959         rcu_read_lock();
1960         list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
1961                 if (!device->in_fs_metadata || !device->bdev ||
1962                     device->is_tgtdev_for_dev_replace)
1963                         continue;
1964
1965                 if (i >= nr_devices)
1966                         break;
1967
1968                 avail_space = device->total_bytes - device->bytes_used;
1969
1970                 /* align with stripe_len */
1971                 avail_space = div_u64(avail_space, BTRFS_STRIPE_LEN);
1972                 avail_space *= BTRFS_STRIPE_LEN;
1973
1974                 /*
1975                  * In order to avoid overwriting the superblock on the drive,
1976                  * btrfs starts at an offset of at least 1MB when doing chunk
1977                  * allocation.
1978                  */
1979                 skip_space = SZ_1M;
1980
1981                 /* user can set the offset in fs_info->alloc_start. */
1982                 if (fs_info->alloc_start &&
1983                     fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1984                     device->total_bytes) {
1985                         rcu_read_unlock();
1986                         skip_space = max(fs_info->alloc_start, skip_space);
1987
1988                         /*
1989                          * btrfs can not use the free space in
1990                          * [0, skip_space - 1], we must subtract it from the
1991                          * total. In order to implement it, we account the used
1992                          * space in this range first.
1993                          */
1994                         ret = btrfs_account_dev_extents_size(device, 0,
1995                                                              skip_space - 1,
1996                                                              &used_space);
1997                         if (ret) {
1998                                 kfree(devices_info);
1999                                 mutex_unlock(&fs_devices->device_list_mutex);
2000                                 return ret;
2001                         }
2002
2003                         rcu_read_lock();
2004
2005                         /* calc the free space in [0, skip_space - 1] */
2006                         skip_space -= used_space;
2007                 }
2008
2009                 /*
2010                  * we can use the free space in [0, skip_space - 1], subtract
2011                  * it from the total.
2012                  */
2013                 if (avail_space && avail_space >= skip_space)
2014                         avail_space -= skip_space;
2015                 else
2016                         avail_space = 0;
2017
2018                 if (avail_space < min_stripe_size)
2019                         continue;
2020
2021                 devices_info[i].dev = device;
2022                 devices_info[i].max_avail = avail_space;
2023
2024                 i++;
2025         }
2026         rcu_read_unlock();
2027         if (fs_info->alloc_start)
2028                 mutex_unlock(&fs_devices->device_list_mutex);
2029
2030         nr_devices = i;
2031
2032         btrfs_descending_sort_devices(devices_info, nr_devices);
2033
2034         i = nr_devices - 1;
2035         avail_space = 0;
2036         while (nr_devices >= min_stripes) {
2037                 if (num_stripes > nr_devices)
2038                         num_stripes = nr_devices;
2039
2040                 if (devices_info[i].max_avail >= min_stripe_size) {
2041                         int j;
2042                         u64 alloc_size;
2043
2044                         avail_space += devices_info[i].max_avail * num_stripes;
2045                         alloc_size = devices_info[i].max_avail;
2046                         for (j = i + 1 - num_stripes; j <= i; j++)
2047                                 devices_info[j].max_avail -= alloc_size;
2048                 }
2049                 i--;
2050                 nr_devices--;
2051         }
2052
2053         kfree(devices_info);
2054         *free_bytes = avail_space;
2055         return 0;
2056 }
2057
2058 /*
2059  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
2060  *
2061  * If there's a redundant raid level at DATA block groups, use the respective
2062  * multiplier to scale the sizes.
2063  *
2064  * Unused device space usage is based on simulating the chunk allocator
2065  * algorithm that respects the device sizes, order of allocations and the
2066  * 'alloc_start' value, this is a close approximation of the actual use but
2067  * there are other factors that may change the result (like a new metadata
2068  * chunk).
2069  *
2070  * If metadata is exhausted, f_bavail will be 0.
2071  */
2072 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
2073 {
2074         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
2075         struct btrfs_super_block *disk_super = fs_info->super_copy;
2076         struct list_head *head = &fs_info->space_info;
2077         struct btrfs_space_info *found;
2078         u64 total_used = 0;
2079         u64 total_free_data = 0;
2080         u64 total_free_meta = 0;
2081         int bits = dentry->d_sb->s_blocksize_bits;
2082         __be32 *fsid = (__be32 *)fs_info->fsid;
2083         unsigned factor = 1;
2084         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
2085         int ret;
2086         u64 thresh = 0;
2087         int mixed = 0;
2088
2089         /*
2090          * holding chunk_mutex to avoid allocating new chunks, holding
2091          * device_list_mutex to avoid the device being removed
2092          */
2093         rcu_read_lock();
2094         list_for_each_entry_rcu(found, head, list) {
2095                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
2096                         int i;
2097
2098                         total_free_data += found->disk_total - found->disk_used;
2099                         total_free_data -=
2100                                 btrfs_account_ro_block_groups_free_space(found);
2101
2102                         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
2103                                 if (!list_empty(&found->block_groups[i])) {
2104                                         switch (i) {
2105                                         case BTRFS_RAID_DUP:
2106                                         case BTRFS_RAID_RAID1:
2107                                         case BTRFS_RAID_RAID10:
2108                                                 factor = 2;
2109                                         }
2110                                 }
2111                         }
2112                 }
2113
2114                 /*
2115                  * Metadata in mixed block goup profiles are accounted in data
2116                  */
2117                 if (!mixed && found->flags & BTRFS_BLOCK_GROUP_METADATA) {
2118                         if (found->flags & BTRFS_BLOCK_GROUP_DATA)
2119                                 mixed = 1;
2120                         else
2121                                 total_free_meta += found->disk_total -
2122                                         found->disk_used;
2123                 }
2124
2125                 total_used += found->disk_used;
2126         }
2127
2128         rcu_read_unlock();
2129
2130         buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
2131         buf->f_blocks >>= bits;
2132         buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
2133
2134         /* Account global block reserve as used, it's in logical size already */
2135         spin_lock(&block_rsv->lock);
2136         /* Mixed block groups accounting is not byte-accurate, avoid overflow */
2137         if (buf->f_bfree >= block_rsv->size >> bits)
2138                 buf->f_bfree -= block_rsv->size >> bits;
2139         else
2140                 buf->f_bfree = 0;
2141         spin_unlock(&block_rsv->lock);
2142
2143         buf->f_bavail = div_u64(total_free_data, factor);
2144         ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
2145         if (ret)
2146                 return ret;
2147         buf->f_bavail += div_u64(total_free_data, factor);
2148         buf->f_bavail = buf->f_bavail >> bits;
2149
2150         /*
2151          * We calculate the remaining metadata space minus global reserve. If
2152          * this is (supposedly) smaller than zero, there's no space. But this
2153          * does not hold in practice, the exhausted state happens where's still
2154          * some positive delta. So we apply some guesswork and compare the
2155          * delta to a 4M threshold.  (Practically observed delta was ~2M.)
2156          *
2157          * We probably cannot calculate the exact threshold value because this
2158          * depends on the internal reservations requested by various
2159          * operations, so some operations that consume a few metadata will
2160          * succeed even if the Avail is zero. But this is better than the other
2161          * way around.
2162          */
2163         thresh = 4 * 1024 * 1024;
2164
2165         if (!mixed && total_free_meta - thresh < block_rsv->size)
2166                 buf->f_bavail = 0;
2167
2168         buf->f_type = BTRFS_SUPER_MAGIC;
2169         buf->f_bsize = dentry->d_sb->s_blocksize;
2170         buf->f_namelen = BTRFS_NAME_LEN;
2171
2172         /* We treat it as constant endianness (it doesn't matter _which_)
2173            because we want the fsid to come out the same whether mounted
2174            on a big-endian or little-endian host */
2175         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
2176         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
2177         /* Mask in the root object ID too, to disambiguate subvols */
2178         buf->f_fsid.val[0] ^= BTRFS_I(d_inode(dentry))->root->objectid >> 32;
2179         buf->f_fsid.val[1] ^= BTRFS_I(d_inode(dentry))->root->objectid;
2180
2181         return 0;
2182 }
2183
2184 static void btrfs_kill_super(struct super_block *sb)
2185 {
2186         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2187         kill_anon_super(sb);
2188         free_fs_info(fs_info);
2189 }
2190
2191 static struct file_system_type btrfs_fs_type = {
2192         .owner          = THIS_MODULE,
2193         .name           = "btrfs",
2194         .mount          = btrfs_mount,
2195         .kill_sb        = btrfs_kill_super,
2196         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2197 };
2198 MODULE_ALIAS_FS("btrfs");
2199
2200 static int btrfs_control_open(struct inode *inode, struct file *file)
2201 {
2202         /*
2203          * The control file's private_data is used to hold the
2204          * transaction when it is started and is used to keep
2205          * track of whether a transaction is already in progress.
2206          */
2207         file->private_data = NULL;
2208         return 0;
2209 }
2210
2211 /*
2212  * used by btrfsctl to scan devices when no FS is mounted
2213  */
2214 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
2215                                 unsigned long arg)
2216 {
2217         struct btrfs_ioctl_vol_args *vol;
2218         struct btrfs_fs_devices *fs_devices;
2219         int ret = -ENOTTY;
2220
2221         if (!capable(CAP_SYS_ADMIN))
2222                 return -EPERM;
2223
2224         vol = memdup_user((void __user *)arg, sizeof(*vol));
2225         if (IS_ERR(vol))
2226                 return PTR_ERR(vol);
2227
2228         switch (cmd) {
2229         case BTRFS_IOC_SCAN_DEV:
2230                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2231                                             &btrfs_fs_type, &fs_devices);
2232                 break;
2233         case BTRFS_IOC_DEVICES_READY:
2234                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2235                                             &btrfs_fs_type, &fs_devices);
2236                 if (ret)
2237                         break;
2238                 ret = !(fs_devices->num_devices == fs_devices->total_devices);
2239                 break;
2240         case BTRFS_IOC_GET_SUPPORTED_FEATURES:
2241                 ret = btrfs_ioctl_get_supported_features((void __user*)arg);
2242                 break;
2243         }
2244
2245         kfree(vol);
2246         return ret;
2247 }
2248
2249 static int btrfs_freeze(struct super_block *sb)
2250 {
2251         struct btrfs_trans_handle *trans;
2252         struct btrfs_root *root = btrfs_sb(sb)->tree_root;
2253
2254         root->fs_info->fs_frozen = 1;
2255         /*
2256          * We don't need a barrier here, we'll wait for any transaction that
2257          * could be in progress on other threads (and do delayed iputs that
2258          * we want to avoid on a frozen filesystem), or do the commit
2259          * ourselves.
2260          */
2261         trans = btrfs_attach_transaction_barrier(root);
2262         if (IS_ERR(trans)) {
2263                 /* no transaction, don't bother */
2264                 if (PTR_ERR(trans) == -ENOENT)
2265                         return 0;
2266                 return PTR_ERR(trans);
2267         }
2268         return btrfs_commit_transaction(trans, root);
2269 }
2270
2271 static int btrfs_unfreeze(struct super_block *sb)
2272 {
2273         struct btrfs_root *root = btrfs_sb(sb)->tree_root;
2274
2275         root->fs_info->fs_frozen = 0;
2276         return 0;
2277 }
2278
2279 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
2280 {
2281         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
2282         struct btrfs_fs_devices *cur_devices;
2283         struct btrfs_device *dev, *first_dev = NULL;
2284         struct list_head *head;
2285         struct rcu_string *name;
2286
2287         mutex_lock(&fs_info->fs_devices->device_list_mutex);
2288         cur_devices = fs_info->fs_devices;
2289         while (cur_devices) {
2290                 head = &cur_devices->devices;
2291                 list_for_each_entry(dev, head, dev_list) {
2292                         if (dev->missing)
2293                                 continue;
2294                         if (!dev->name)
2295                                 continue;
2296                         if (!first_dev || dev->devid < first_dev->devid)
2297                                 first_dev = dev;
2298                 }
2299                 cur_devices = cur_devices->seed;
2300         }
2301
2302         if (first_dev) {
2303                 rcu_read_lock();
2304                 name = rcu_dereference(first_dev->name);
2305                 seq_escape(m, name->str, " \t\n\\");
2306                 rcu_read_unlock();
2307         } else {
2308                 WARN_ON(1);
2309         }
2310         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2311         return 0;
2312 }
2313
2314 static const struct super_operations btrfs_super_ops = {
2315         .drop_inode     = btrfs_drop_inode,
2316         .evict_inode    = btrfs_evict_inode,
2317         .put_super      = btrfs_put_super,
2318         .sync_fs        = btrfs_sync_fs,
2319         .show_options   = btrfs_show_options,
2320         .show_devname   = btrfs_show_devname,
2321         .write_inode    = btrfs_write_inode,
2322         .alloc_inode    = btrfs_alloc_inode,
2323         .destroy_inode  = btrfs_destroy_inode,
2324         .statfs         = btrfs_statfs,
2325         .remount_fs     = btrfs_remount,
2326         .freeze_fs      = btrfs_freeze,
2327         .unfreeze_fs    = btrfs_unfreeze,
2328 };
2329
2330 static const struct file_operations btrfs_ctl_fops = {
2331         .open = btrfs_control_open,
2332         .unlocked_ioctl  = btrfs_control_ioctl,
2333         .compat_ioctl = btrfs_control_ioctl,
2334         .owner   = THIS_MODULE,
2335         .llseek = noop_llseek,
2336 };
2337
2338 static struct miscdevice btrfs_misc = {
2339         .minor          = BTRFS_MINOR,
2340         .name           = "btrfs-control",
2341         .fops           = &btrfs_ctl_fops
2342 };
2343
2344 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2345 MODULE_ALIAS("devname:btrfs-control");
2346
2347 static int btrfs_interface_init(void)
2348 {
2349         return misc_register(&btrfs_misc);
2350 }
2351
2352 static void btrfs_interface_exit(void)
2353 {
2354         misc_deregister(&btrfs_misc);
2355 }
2356
2357 static void btrfs_print_mod_info(void)
2358 {
2359         pr_info("Btrfs loaded, crc32c=%s"
2360 #ifdef CONFIG_BTRFS_DEBUG
2361                         ", debug=on"
2362 #endif
2363 #ifdef CONFIG_BTRFS_ASSERT
2364                         ", assert=on"
2365 #endif
2366 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2367                         ", integrity-checker=on"
2368 #endif
2369                         "\n",
2370                         btrfs_crc32c_impl());
2371 }
2372
2373 static int __init init_btrfs_fs(void)
2374 {
2375         int err;
2376
2377         err = btrfs_hash_init();
2378         if (err)
2379                 return err;
2380
2381         btrfs_props_init();
2382
2383         err = btrfs_init_sysfs();
2384         if (err)
2385                 goto free_hash;
2386
2387         btrfs_init_compress();
2388
2389         err = btrfs_init_cachep();
2390         if (err)
2391                 goto free_compress;
2392
2393         err = extent_io_init();
2394         if (err)
2395                 goto free_cachep;
2396
2397         err = extent_map_init();
2398         if (err)
2399                 goto free_extent_io;
2400
2401         err = ordered_data_init();
2402         if (err)
2403                 goto free_extent_map;
2404
2405         err = btrfs_delayed_inode_init();
2406         if (err)
2407                 goto free_ordered_data;
2408
2409         err = btrfs_auto_defrag_init();
2410         if (err)
2411                 goto free_delayed_inode;
2412
2413         err = btrfs_delayed_ref_init();
2414         if (err)
2415                 goto free_auto_defrag;
2416
2417         err = btrfs_prelim_ref_init();
2418         if (err)
2419                 goto free_delayed_ref;
2420
2421         err = btrfs_end_io_wq_init();
2422         if (err)
2423                 goto free_prelim_ref;
2424
2425         err = btrfs_interface_init();
2426         if (err)
2427                 goto free_end_io_wq;
2428
2429         btrfs_init_lockdep();
2430
2431         btrfs_print_mod_info();
2432
2433         err = btrfs_run_sanity_tests();
2434         if (err)
2435                 goto unregister_ioctl;
2436
2437         err = register_filesystem(&btrfs_fs_type);
2438         if (err)
2439                 goto unregister_ioctl;
2440
2441         return 0;
2442
2443 unregister_ioctl:
2444         btrfs_interface_exit();
2445 free_end_io_wq:
2446         btrfs_end_io_wq_exit();
2447 free_prelim_ref:
2448         btrfs_prelim_ref_exit();
2449 free_delayed_ref:
2450         btrfs_delayed_ref_exit();
2451 free_auto_defrag:
2452         btrfs_auto_defrag_exit();
2453 free_delayed_inode:
2454         btrfs_delayed_inode_exit();
2455 free_ordered_data:
2456         ordered_data_exit();
2457 free_extent_map:
2458         extent_map_exit();
2459 free_extent_io:
2460         extent_io_exit();
2461 free_cachep:
2462         btrfs_destroy_cachep();
2463 free_compress:
2464         btrfs_exit_compress();
2465         btrfs_exit_sysfs();
2466 free_hash:
2467         btrfs_hash_exit();
2468         return err;
2469 }
2470
2471 static void __exit exit_btrfs_fs(void)
2472 {
2473         btrfs_destroy_cachep();
2474         btrfs_delayed_ref_exit();
2475         btrfs_auto_defrag_exit();
2476         btrfs_delayed_inode_exit();
2477         btrfs_prelim_ref_exit();
2478         ordered_data_exit();
2479         extent_map_exit();
2480         extent_io_exit();
2481         btrfs_interface_exit();
2482         btrfs_end_io_wq_exit();
2483         unregister_filesystem(&btrfs_fs_type);
2484         btrfs_exit_sysfs();
2485         btrfs_cleanup_fs_uuids();
2486         btrfs_exit_compress();
2487         btrfs_hash_exit();
2488 }
2489
2490 late_initcall(init_btrfs_fs);
2491 module_exit(exit_btrfs_fs)
2492
2493 MODULE_LICENSE("GPL");