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