fs/btrfs/super.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/blkdev.h>
   7 #include <linux/module.h>
   8 #include <linux/buffer_head.h>
   9 #include <linux/fs.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/highmem.h>
  12 #include <linux/time.h>
  13 #include <linux/init.h>
  14 #include <linux/seq_file.h>
  15 #include <linux/string.h>
  16 #include <linux/backing-dev.h>
  17 #include <linux/mount.h>
  18 #include <linux/mpage.h>
  19 #include <linux/swap.h>
  20 #include <linux/writeback.h>
  21 #include <linux/statfs.h>
  22 #include <linux/compat.h>
  23 #include <linux/parser.h>
  24 #include <linux/ctype.h>
  25 #include <linux/namei.h>
  26 #include <linux/miscdevice.h>
  27 #include <linux/magic.h>
  28 #include <linux/slab.h>
  29 #include <linux/cleancache.h>
  30 #include <linux/ratelimit.h>
  31 #include <linux/crc32c.h>
  32 #include <linux/btrfs.h>
  33 #include "delayed-inode.h"
  34 #include "ctree.h"
  35 #include "disk-io.h"
  36 #include "transaction.h"
  37 #include "btrfs_inode.h"
  38 #include "print-tree.h"
  39 #include "props.h"
  40 #include "xattr.h"
  41 #include "volumes.h"
  42 #include "export.h"
  43 #include "compression.h"
  44 #include "rcu-string.h"
  45 #include "dev-replace.h"
  46 #include "free-space-cache.h"
  47 #include "backref.h"
  48 #include "tests/btrfs-tests.h"
  49
  50 #include "qgroup.h"
  51 #define CREATE_TRACE_POINTS
  52 #include <trace/events/btrfs.h>
  53
  54 static const struct super_operations btrfs_super_ops;
  55
  56 /*
  57  * Types for mounting the default subvolume and a subvolume explicitly
  58  * requested by subvol=/path. That way the callchain is straightforward and we
  59  * don't have to play tricks with the mount options and recursive calls to
  60  * btrfs_mount.
  61  *
  62  * The new btrfs_root_fs_type also servers as a tag for the bdev_holder.
  63  */
  64 static struct file_system_type btrfs_fs_type;
  65 static struct file_system_type btrfs_root_fs_type;
  66
  67 static int btrfs_remount(struct super_block *sb, int *flags, char *data);
  68
  69 const char *btrfs_decode_error(int errno)
  70 {
  71         char *errstr = "unknown";
  72
  73         switch (errno) {
  74         case -EIO:
  75                 errstr = "IO failure";
  76                 break;
  77         case -ENOMEM:
  78                 errstr = "Out of memory";
  79                 break;
  80         case -EROFS:
  81                 errstr = "Readonly filesystem";
  82                 break;
  83         case -EEXIST:
  84                 errstr = "Object already exists";
  85                 break;
  86         case -ENOSPC:
  87                 errstr = "No space left";
  88                 break;
  89         case -ENOENT:
  90                 errstr = "No such entry";
  91                 break;
  92         }
  93
  94         return errstr;
  95 }
  96
  97 /*
  98  * __btrfs_handle_fs_error decodes expected errors from the caller and
  99  * invokes the approciate error response.
 100  */
 101 __cold
 102 void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function,
 103                        unsigned int line, int errno, const char *fmt, ...)
 104 {
 105         struct super_block *sb = fs_info->sb;
 106 #ifdef CONFIG_PRINTK
 107         const char *errstr;
 108 #endif
 109
 110         /*
 111          * Special case: if the error is EROFS, and we're already
 112          * under SB_RDONLY, then it is safe here.
 113          */
 114         if (errno == -EROFS && sb_rdonly(sb))
 115                 return;
 116
 117 #ifdef CONFIG_PRINTK
 118         errstr = btrfs_decode_error(errno);
 119         if (fmt) {
 120                 struct va_format vaf;
 121                 va_list args;
 122
 123                 va_start(args, fmt);
 124                 vaf.fmt = fmt;
 125                 vaf.va = &args;
 126
 127                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s (%pV)\n",
 128                         sb->s_id, function, line, errno, errstr, &vaf);
 129                 va_end(args);
 130         } else {
 131                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s\n",
 132                         sb->s_id, function, line, errno, errstr);
 133         }
 134 #endif
 135
 136         /*
 137          * Today we only save the error info to memory.  Long term we'll
 138          * also send it down to the disk
 139          */
 140         set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
 141
 142         /* Don't go through full error handling during mount */
 143         if (!(sb->s_flags & SB_BORN))
 144                 return;
 145
 146         if (sb_rdonly(sb))
 147                 return;
 148
 149         /* btrfs handle error by forcing the filesystem readonly */
 150         sb->s_flags |= SB_RDONLY;
 151         btrfs_info(fs_info, "forced readonly");
 152         /*
 153          * Note that a running device replace operation is not canceled here
 154          * although there is no way to update the progress. It would add the
 155          * risk of a deadlock, therefore the canceling is omitted. The only
 156          * penalty is that some I/O remains active until the procedure
 157          * completes. The next time when the filesystem is mounted writeable
 158          * again, the device replace operation continues.
 159          */
 160 }
 161
 162 #ifdef CONFIG_PRINTK
 163 static const char * const logtypes[] = {
 164         "emergency",
 165         "alert",
 166         "critical",
 167         "error",
 168         "warning",
 169         "notice",
 170         "info",
 171         "debug",
 172 };
 173
 174
 175 /*
 176  * Use one ratelimit state per log level so that a flood of less important
 177  * messages doesn't cause more important ones to be dropped.
 178  */
 179 static struct ratelimit_state printk_limits[] = {
 180         RATELIMIT_STATE_INIT(printk_limits[0], DEFAULT_RATELIMIT_INTERVAL, 100),
 181         RATELIMIT_STATE_INIT(printk_limits[1], DEFAULT_RATELIMIT_INTERVAL, 100),
 182         RATELIMIT_STATE_INIT(printk_limits[2], DEFAULT_RATELIMIT_INTERVAL, 100),
 183         RATELIMIT_STATE_INIT(printk_limits[3], DEFAULT_RATELIMIT_INTERVAL, 100),
 184         RATELIMIT_STATE_INIT(printk_limits[4], DEFAULT_RATELIMIT_INTERVAL, 100),
 185         RATELIMIT_STATE_INIT(printk_limits[5], DEFAULT_RATELIMIT_INTERVAL, 100),
 186         RATELIMIT_STATE_INIT(printk_limits[6], DEFAULT_RATELIMIT_INTERVAL, 100),
 187         RATELIMIT_STATE_INIT(printk_limits[7], DEFAULT_RATELIMIT_INTERVAL, 100),
 188 };
 189
 190 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 191 {
 192         char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1] = "\0";
 193         struct va_format vaf;
 194         va_list args;
 195         int kern_level;
 196         const char *type = logtypes[4];
 197         struct ratelimit_state *ratelimit = &printk_limits[4];
 198
 199         va_start(args, fmt);
 200
 201         while ((kern_level = printk_get_level(fmt)) != 0) {
 202                 size_t size = printk_skip_level(fmt) - fmt;
 203
 204                 if (kern_level >= '0' && kern_level <= '7') {
 205                         memcpy(lvl, fmt,  size);
 206                         lvl[size] = '\0';
 207                         type = logtypes[kern_level - '0'];
 208                         ratelimit = &printk_limits[kern_level - '0'];
 209                 }
 210                 fmt += size;
 211         }
 212
 213         vaf.fmt = fmt;
 214         vaf.va = &args;
 215
 216         if (__ratelimit(ratelimit))
 217                 printk("%sBTRFS %s (device %s): %pV\n", lvl, type,
 218                         fs_info ? fs_info->sb->s_id : "<unknown>", &vaf);
 219
 220         va_end(args);
 221 }
 222 #endif
 223
 224 /*
 225  * We only mark the transaction aborted and then set the file system read-only.
 226  * This will prevent new transactions from starting or trying to join this
 227  * one.
 228  *
 229  * This means that error recovery at the call site is limited to freeing
 230  * any local memory allocations and passing the error code up without
 231  * further cleanup. The transaction should complete as it normally would
 232  * in the call path but will return -EIO.
 233  *
 234  * We'll complete the cleanup in btrfs_end_transaction and
 235  * btrfs_commit_transaction.
 236  */
 237 __cold
 238 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 239                                const char *function,
 240                                unsigned int line, int errno)
 241 {
 242         struct btrfs_fs_info *fs_info = trans->fs_info;
 243
 244         trans->aborted = errno;
 245         /* Nothing used. The other threads that have joined this
 246          * transaction may be able to continue. */
 247         if (!trans->dirty && list_empty(&trans->new_bgs)) {
 248                 const char *errstr;
 249
 250                 errstr = btrfs_decode_error(errno);
 251                 btrfs_warn(fs_info,
 252                            "%s:%d: Aborting unused transaction(%s).",
 253                            function, line, errstr);
 254                 return;
 255         }
 256         WRITE_ONCE(trans->transaction->aborted, errno);
 257         /* Wake up anybody who may be waiting on this transaction */
 258         wake_up(&fs_info->transaction_wait);
 259         wake_up(&fs_info->transaction_blocked_wait);
 260         __btrfs_handle_fs_error(fs_info, function, line, errno, NULL);
 261 }
 262 /*
 263  * __btrfs_panic decodes unexpected, fatal errors from the caller,
 264  * issues an alert, and either panics or BUGs, depending on mount options.
 265  */
 266 __cold
 267 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 268                    unsigned int line, int errno, const char *fmt, ...)
 269 {
 270         char *s_id = "<unknown>";
 271         const char *errstr;
 272         struct va_format vaf = { .fmt = fmt };
 273         va_list args;
 274
 275         if (fs_info)
 276                 s_id = fs_info->sb->s_id;
 277
 278         va_start(args, fmt);
 279         vaf.va = &args;
 280
 281         errstr = btrfs_decode_error(errno);
 282         if (fs_info && (btrfs_test_opt(fs_info, PANIC_ON_FATAL_ERROR)))
 283                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
 284                         s_id, function, line, &vaf, errno, errstr);
 285
 286         btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
 287                    function, line, &vaf, errno, errstr);
 288         va_end(args);
 289         /* Caller calls BUG() */
 290 }
 291
 292 static void btrfs_put_super(struct super_block *sb)
 293 {
 294         close_ctree(btrfs_sb(sb));
 295 }
 296
 297 enum {
 298         Opt_acl, Opt_noacl,
 299         Opt_clear_cache,
 300         Opt_commit_interval,
 301         Opt_compress,
 302         Opt_compress_force,
 303         Opt_compress_force_type,
 304         Opt_compress_type,
 305         Opt_degraded,
 306         Opt_device,
 307         Opt_fatal_errors,
 308         Opt_flushoncommit, Opt_noflushoncommit,
 309         Opt_inode_cache, Opt_noinode_cache,
 310         Opt_max_inline,
 311         Opt_barrier, Opt_nobarrier,
 312         Opt_datacow, Opt_nodatacow,
 313         Opt_datasum, Opt_nodatasum,
 314         Opt_defrag, Opt_nodefrag,
 315         Opt_discard, Opt_nodiscard,
 316         Opt_nologreplay,
 317         Opt_norecovery,
 318         Opt_ratio,
 319         Opt_rescan_uuid_tree,
 320         Opt_skip_balance,
 321         Opt_space_cache, Opt_no_space_cache,
 322         Opt_space_cache_version,
 323         Opt_ssd, Opt_nossd,
 324         Opt_ssd_spread, Opt_nossd_spread,
 325         Opt_subvol,
 326         Opt_subvolid,
 327         Opt_thread_pool,
 328         Opt_treelog, Opt_notreelog,
 329         Opt_usebackuproot,
 330         Opt_user_subvol_rm_allowed,
 331
 332         /* Deprecated options */
 333         Opt_alloc_start,
 334         Opt_recovery,
 335         Opt_subvolrootid,
 336
 337         /* Debugging options */
 338         Opt_check_integrity,
 339         Opt_check_integrity_including_extent_data,
 340         Opt_check_integrity_print_mask,
 341         Opt_enospc_debug, Opt_noenospc_debug,
 342 #ifdef CONFIG_BTRFS_DEBUG
 343         Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 344 #endif
 345 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 346         Opt_ref_verify,
 347 #endif
 348         Opt_err,
 349 };
 350
 351 static const match_table_t tokens = {
 352         {Opt_acl, "acl"},
 353         {Opt_noacl, "noacl"},
 354         {Opt_clear_cache, "clear_cache"},
 355         {Opt_commit_interval, "commit=%u"},
 356         {Opt_compress, "compress"},
 357         {Opt_compress_type, "compress=%s"},
 358         {Opt_compress_force, "compress-force"},
 359         {Opt_compress_force_type, "compress-force=%s"},
 360         {Opt_degraded, "degraded"},
 361         {Opt_device, "device=%s"},
 362         {Opt_fatal_errors, "fatal_errors=%s"},
 363         {Opt_flushoncommit, "flushoncommit"},
 364         {Opt_noflushoncommit, "noflushoncommit"},
 365         {Opt_inode_cache, "inode_cache"},
 366         {Opt_noinode_cache, "noinode_cache"},
 367         {Opt_max_inline, "max_inline=%s"},
 368         {Opt_barrier, "barrier"},
 369         {Opt_nobarrier, "nobarrier"},
 370         {Opt_datacow, "datacow"},
 371         {Opt_nodatacow, "nodatacow"},
 372         {Opt_datasum, "datasum"},
 373         {Opt_nodatasum, "nodatasum"},
 374         {Opt_defrag, "autodefrag"},
 375         {Opt_nodefrag, "noautodefrag"},
 376         {Opt_discard, "discard"},
 377         {Opt_nodiscard, "nodiscard"},
 378         {Opt_nologreplay, "nologreplay"},
 379         {Opt_norecovery, "norecovery"},
 380         {Opt_ratio, "metadata_ratio=%u"},
 381         {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
 382         {Opt_skip_balance, "skip_balance"},
 383         {Opt_space_cache, "space_cache"},
 384         {Opt_no_space_cache, "nospace_cache"},
 385         {Opt_space_cache_version, "space_cache=%s"},
 386         {Opt_ssd, "ssd"},
 387         {Opt_nossd, "nossd"},
 388         {Opt_ssd_spread, "ssd_spread"},
 389         {Opt_nossd_spread, "nossd_spread"},
 390         {Opt_subvol, "subvol=%s"},
 391         {Opt_subvolid, "subvolid=%s"},
 392         {Opt_thread_pool, "thread_pool=%u"},
 393         {Opt_treelog, "treelog"},
 394         {Opt_notreelog, "notreelog"},
 395         {Opt_usebackuproot, "usebackuproot"},
 396         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 397
 398         /* Deprecated options */
 399         {Opt_alloc_start, "alloc_start=%s"},
 400         {Opt_recovery, "recovery"},
 401         {Opt_subvolrootid, "subvolrootid=%d"},
 402
 403         /* Debugging options */
 404         {Opt_check_integrity, "check_int"},
 405         {Opt_check_integrity_including_extent_data, "check_int_data"},
 406         {Opt_check_integrity_print_mask, "check_int_print_mask=%u"},
 407         {Opt_enospc_debug, "enospc_debug"},
 408         {Opt_noenospc_debug, "noenospc_debug"},
 409 #ifdef CONFIG_BTRFS_DEBUG
 410         {Opt_fragment_data, "fragment=data"},
 411         {Opt_fragment_metadata, "fragment=metadata"},
 412         {Opt_fragment_all, "fragment=all"},
 413 #endif
 414 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 415         {Opt_ref_verify, "ref_verify"},
 416 #endif
 417         {Opt_err, NULL},
 418 };
 419
 420 /*
 421  * Regular mount options parser.  Everything that is needed only when
 422  * reading in a new superblock is parsed here.
 423  * XXX JDM: This needs to be cleaned up for remount.
 424  */
 425 int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 426                         unsigned long new_flags)
 427 {
 428         substring_t args[MAX_OPT_ARGS];
 429         char *p, *num;
 430         u64 cache_gen;
 431         int intarg;
 432         int ret = 0;
 433         char *compress_type;
 434         bool compress_force = false;
 435         enum btrfs_compression_type saved_compress_type;
 436         bool saved_compress_force;
 437         int no_compress = 0;
 438
 439         cache_gen = btrfs_super_cache_generation(info->super_copy);
 440         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
 441                 btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
 442         else if (cache_gen)
 443                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 444
 445         /*
 446          * Even the options are empty, we still need to do extra check
 447          * against new flags
 448          */
 449         if (!options)
 450                 goto check;
 451
 452         while ((p = strsep(&options, ",")) != NULL) {
 453                 int token;
 454                 if (!*p)
 455                         continue;
 456
 457                 token = match_token(p, tokens, args);
 458                 switch (token) {
 459                 case Opt_degraded:
 460                         btrfs_info(info, "allowing degraded mounts");
 461                         btrfs_set_opt(info->mount_opt, DEGRADED);
 462                         break;
 463                 case Opt_subvol:
 464                 case Opt_subvolid:
 465                 case Opt_subvolrootid:
 466                 case Opt_device:
 467                         /*
 468                          * These are parsed by btrfs_parse_subvol_options
 469                          * and btrfs_parse_early_options
 470                          * and can be happily ignored here.
 471                          */
 472                         break;
 473                 case Opt_nodatasum:
 474                         btrfs_set_and_info(info, NODATASUM,
 475                                            "setting nodatasum");
 476                         break;
 477                 case Opt_datasum:
 478                         if (btrfs_test_opt(info, NODATASUM)) {
 479                                 if (btrfs_test_opt(info, NODATACOW))
 480                                         btrfs_info(info,
 481                                                    "setting datasum, datacow enabled");
 482                                 else
 483                                         btrfs_info(info, "setting datasum");
 484                         }
 485                         btrfs_clear_opt(info->mount_opt, NODATACOW);
 486                         btrfs_clear_opt(info->mount_opt, NODATASUM);
 487                         break;
 488                 case Opt_nodatacow:
 489                         if (!btrfs_test_opt(info, NODATACOW)) {
 490                                 if (!btrfs_test_opt(info, COMPRESS) ||
 491                                     !btrfs_test_opt(info, FORCE_COMPRESS)) {
 492                                         btrfs_info(info,
 493                                                    "setting nodatacow, compression disabled");
 494                                 } else {
 495                                         btrfs_info(info, "setting nodatacow");
 496                                 }
 497                         }
 498                         btrfs_clear_opt(info->mount_opt, COMPRESS);
 499                         btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 500                         btrfs_set_opt(info->mount_opt, NODATACOW);
 501                         btrfs_set_opt(info->mount_opt, NODATASUM);
 502                         break;
 503                 case Opt_datacow:
 504                         btrfs_clear_and_info(info, NODATACOW,
 505                                              "setting datacow");
 506                         break;
 507                 case Opt_compress_force:
 508                 case Opt_compress_force_type:
 509                         compress_force = true;
 510                         /* Fallthrough */
 511                 case Opt_compress:
 512                 case Opt_compress_type:
 513                         saved_compress_type = btrfs_test_opt(info,
 514                                                              COMPRESS) ?
 515                                 info->compress_type : BTRFS_COMPRESS_NONE;
 516                         saved_compress_force =
 517                                 btrfs_test_opt(info, FORCE_COMPRESS);
 518                         if (token == Opt_compress ||
 519                             token == Opt_compress_force ||
 520                             strncmp(args[0].from, "zlib", 4) == 0) {
 521                                 compress_type = "zlib";
 522
 523                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 524                                 info->compress_level = BTRFS_ZLIB_DEFAULT_LEVEL;
 525                                 /*
 526                                  * args[0] contains uninitialized data since
 527                                  * for these tokens we don't expect any
 528                                  * parameter.
 529                                  */
 530                                 if (token != Opt_compress &&
 531                                     token != Opt_compress_force)
 532                                         info->compress_level =
 533                                           btrfs_compress_str2level(args[0].from);
 534                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 535                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 536                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 537                                 no_compress = 0;
 538                         } else if (strncmp(args[0].from, "lzo", 3) == 0) {
 539                                 compress_type = "lzo";
 540                                 info->compress_type = BTRFS_COMPRESS_LZO;
 541                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 542                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 543                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 544                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
 545                                 no_compress = 0;
 546                         } else if (strcmp(args[0].from, "zstd") == 0) {
 547                                 compress_type = "zstd";
 548                                 info->compress_type = BTRFS_COMPRESS_ZSTD;
 549                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 550                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 551                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 552                                 btrfs_set_fs_incompat(info, COMPRESS_ZSTD);
 553                                 no_compress = 0;
 554                         } else if (strncmp(args[0].from, "no", 2) == 0) {
 555                                 compress_type = "no";
 556                                 btrfs_clear_opt(info->mount_opt, COMPRESS);
 557                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 558                                 compress_force = false;
 559                                 no_compress++;
 560                         } else {
 561                                 ret = -EINVAL;
 562                                 goto out;
 563                         }
 564
 565                         if (compress_force) {
 566                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 567                         } else {
 568                                 /*
 569                                  * If we remount from compress-force=xxx to
 570                                  * compress=xxx, we need clear FORCE_COMPRESS
 571                                  * flag, otherwise, there is no way for users
 572                                  * to disable forcible compression separately.
 573                                  */
 574                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 575                         }
 576                         if ((btrfs_test_opt(info, COMPRESS) &&
 577                              (info->compress_type != saved_compress_type ||
 578                               compress_force != saved_compress_force)) ||
 579                             (!btrfs_test_opt(info, COMPRESS) &&
 580                              no_compress == 1)) {
 581                                 btrfs_info(info, "%s %s compression, level %d",
 582                                            (compress_force) ? "force" : "use",
 583                                            compress_type, info->compress_level);
 584                         }
 585                         compress_force = false;
 586                         break;
 587                 case Opt_ssd:
 588                         btrfs_set_and_info(info, SSD,
 589                                            "enabling ssd optimizations");
 590                         btrfs_clear_opt(info->mount_opt, NOSSD);
 591                         break;
 592                 case Opt_ssd_spread:
 593                         btrfs_set_and_info(info, SSD,
 594                                            "enabling ssd optimizations");
 595                         btrfs_set_and_info(info, SSD_SPREAD,
 596                                            "using spread ssd allocation scheme");
 597                         btrfs_clear_opt(info->mount_opt, NOSSD);
 598                         break;
 599                 case Opt_nossd:
 600                         btrfs_set_opt(info->mount_opt, NOSSD);
 601                         btrfs_clear_and_info(info, SSD,
 602                                              "not using ssd optimizations");
 603                         /* Fallthrough */
 604                 case Opt_nossd_spread:
 605                         btrfs_clear_and_info(info, SSD_SPREAD,
 606                                              "not using spread ssd allocation scheme");
 607                         break;
 608                 case Opt_barrier:
 609                         btrfs_clear_and_info(info, NOBARRIER,
 610                                              "turning on barriers");
 611                         break;
 612                 case Opt_nobarrier:
 613                         btrfs_set_and_info(info, NOBARRIER,
 614                                            "turning off barriers");
 615                         break;
 616                 case Opt_thread_pool:
 617                         ret = match_int(&args[0], &intarg);
 618                         if (ret) {
 619                                 goto out;
 620                         } else if (intarg == 0) {
 621                                 ret = -EINVAL;
 622                                 goto out;
 623                         }
 624                         info->thread_pool_size = intarg;
 625                         break;
 626                 case Opt_max_inline:
 627                         num = match_strdup(&args[0]);
 628                         if (num) {
 629                                 info->max_inline = memparse(num, NULL);
 630                                 kfree(num);
 631
 632                                 if (info->max_inline) {
 633                                         info->max_inline = min_t(u64,
 634                                                 info->max_inline,
 635                                                 info->sectorsize);
 636                                 }
 637                                 btrfs_info(info, "max_inline at %llu",
 638                                            info->max_inline);
 639                         } else {
 640                                 ret = -ENOMEM;
 641                                 goto out;
 642                         }
 643                         break;
 644                 case Opt_alloc_start:
 645                         btrfs_info(info,
 646                                 "option alloc_start is obsolete, ignored");
 647                         break;
 648                 case Opt_acl:
 649 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 650                         info->sb->s_flags |= SB_POSIXACL;
 651                         break;
 652 #else
 653                         btrfs_err(info, "support for ACL not compiled in!");
 654                         ret = -EINVAL;
 655                         goto out;
 656 #endif
 657                 case Opt_noacl:
 658                         info->sb->s_flags &= ~SB_POSIXACL;
 659                         break;
 660                 case Opt_notreelog:
 661                         btrfs_set_and_info(info, NOTREELOG,
 662                                            "disabling tree log");
 663                         break;
 664                 case Opt_treelog:
 665                         btrfs_clear_and_info(info, NOTREELOG,
 666                                              "enabling tree log");
 667                         break;
 668                 case Opt_norecovery:
 669                 case Opt_nologreplay:
 670                         btrfs_set_and_info(info, NOLOGREPLAY,
 671                                            "disabling log replay at mount time");
 672                         break;
 673                 case Opt_flushoncommit:
 674                         btrfs_set_and_info(info, FLUSHONCOMMIT,
 675                                            "turning on flush-on-commit");
 676                         break;
 677                 case Opt_noflushoncommit:
 678                         btrfs_clear_and_info(info, FLUSHONCOMMIT,
 679                                              "turning off flush-on-commit");
 680                         break;
 681                 case Opt_ratio:
 682                         ret = match_int(&args[0], &intarg);
 683                         if (ret)
 684                                 goto out;
 685                         info->metadata_ratio = intarg;
 686                         btrfs_info(info, "metadata ratio %u",
 687                                    info->metadata_ratio);
 688                         break;
 689                 case Opt_discard:
 690                         btrfs_set_and_info(info, DISCARD,
 691                                            "turning on discard");
 692                         break;
 693                 case Opt_nodiscard:
 694                         btrfs_clear_and_info(info, DISCARD,
 695                                              "turning off discard");
 696                         break;
 697                 case Opt_space_cache:
 698                 case Opt_space_cache_version:
 699                         if (token == Opt_space_cache ||
 700                             strcmp(args[0].from, "v1") == 0) {
 701                                 btrfs_clear_opt(info->mount_opt,
 702                                                 FREE_SPACE_TREE);
 703                                 btrfs_set_and_info(info, SPACE_CACHE,
 704                                            "enabling disk space caching");
 705                         } else if (strcmp(args[0].from, "v2") == 0) {
 706                                 btrfs_clear_opt(info->mount_opt,
 707                                                 SPACE_CACHE);
 708                                 btrfs_set_and_info(info, FREE_SPACE_TREE,
 709                                                    "enabling free space tree");
 710                         } else {
 711                                 ret = -EINVAL;
 712                                 goto out;
 713                         }
 714                         break;
 715                 case Opt_rescan_uuid_tree:
 716                         btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
 717                         break;
 718                 case Opt_no_space_cache:
 719                         if (btrfs_test_opt(info, SPACE_CACHE)) {
 720                                 btrfs_clear_and_info(info, SPACE_CACHE,
 721                                              "disabling disk space caching");
 722                         }
 723                         if (btrfs_test_opt(info, FREE_SPACE_TREE)) {
 724                                 btrfs_clear_and_info(info, FREE_SPACE_TREE,
 725                                              "disabling free space tree");
 726                         }
 727                         break;
 728                 case Opt_inode_cache:
 729                         btrfs_set_pending_and_info(info, INODE_MAP_CACHE,
 730                                            "enabling inode map caching");
 731                         break;
 732                 case Opt_noinode_cache:
 733                         btrfs_clear_pending_and_info(info, INODE_MAP_CACHE,
 734                                              "disabling inode map caching");
 735                         break;
 736                 case Opt_clear_cache:
 737                         btrfs_set_and_info(info, CLEAR_CACHE,
 738                                            "force clearing of disk cache");
 739                         break;
 740                 case Opt_user_subvol_rm_allowed:
 741                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 742                         break;
 743                 case Opt_enospc_debug:
 744                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 745                         break;
 746                 case Opt_noenospc_debug:
 747                         btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
 748                         break;
 749                 case Opt_defrag:
 750                         btrfs_set_and_info(info, AUTO_DEFRAG,
 751                                            "enabling auto defrag");
 752                         break;
 753                 case Opt_nodefrag:
 754                         btrfs_clear_and_info(info, AUTO_DEFRAG,
 755                                              "disabling auto defrag");
 756                         break;
 757                 case Opt_recovery:
 758                         btrfs_warn(info,
 759                                    "'recovery' is deprecated, use 'usebackuproot' instead");
 760                 case Opt_usebackuproot:
 761                         btrfs_info(info,
 762                                    "trying to use backup root at mount time");
 763                         btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
 764                         break;
 765                 case Opt_skip_balance:
 766                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 767                         break;
 768 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 769                 case Opt_check_integrity_including_extent_data:
 770                         btrfs_info(info,
 771                                    "enabling check integrity including extent data");
 772                         btrfs_set_opt(info->mount_opt,
 773                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 774                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 775                         break;
 776                 case Opt_check_integrity:
 777                         btrfs_info(info, "enabling check integrity");
 778                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 779                         break;
 780                 case Opt_check_integrity_print_mask:
 781                         ret = match_int(&args[0], &intarg);
 782                         if (ret)
 783                                 goto out;
 784                         info->check_integrity_print_mask = intarg;
 785                         btrfs_info(info, "check_integrity_print_mask 0x%x",
 786                                    info->check_integrity_print_mask);
 787                         break;
 788 #else
 789                 case Opt_check_integrity_including_extent_data:
 790                 case Opt_check_integrity:
 791                 case Opt_check_integrity_print_mask:
 792                         btrfs_err(info,
 793                                   "support for check_integrity* not compiled in!");
 794                         ret = -EINVAL;
 795                         goto out;
 796 #endif
 797                 case Opt_fatal_errors:
 798                         if (strcmp(args[0].from, "panic") == 0)
 799                                 btrfs_set_opt(info->mount_opt,
 800                                               PANIC_ON_FATAL_ERROR);
 801                         else if (strcmp(args[0].from, "bug") == 0)
 802                                 btrfs_clear_opt(info->mount_opt,
 803                                               PANIC_ON_FATAL_ERROR);
 804                         else {
 805                                 ret = -EINVAL;
 806                                 goto out;
 807                         }
 808                         break;
 809                 case Opt_commit_interval:
 810                         intarg = 0;
 811                         ret = match_int(&args[0], &intarg);
 812                         if (ret)
 813                                 goto out;
 814                         if (intarg == 0) {
 815                                 btrfs_info(info,
 816                                            "using default commit interval %us",
 817                                            BTRFS_DEFAULT_COMMIT_INTERVAL);
 818                                 intarg = BTRFS_DEFAULT_COMMIT_INTERVAL;
 819                         } else if (intarg > 300) {
 820                                 btrfs_warn(info, "excessive commit interval %d",
 821                                            intarg);
 822                         }
 823                         info->commit_interval = intarg;
 824                         break;
 825 #ifdef CONFIG_BTRFS_DEBUG
 826                 case Opt_fragment_all:
 827                         btrfs_info(info, "fragmenting all space");
 828                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 829                         btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
 830                         break;
 831                 case Opt_fragment_metadata:
 832                         btrfs_info(info, "fragmenting metadata");
 833                         btrfs_set_opt(info->mount_opt,
 834                                       FRAGMENT_METADATA);
 835                         break;
 836                 case Opt_fragment_data:
 837                         btrfs_info(info, "fragmenting data");
 838                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 839                         break;
 840 #endif
 841 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 842                 case Opt_ref_verify:
 843                         btrfs_info(info, "doing ref verification");
 844                         btrfs_set_opt(info->mount_opt, REF_VERIFY);
 845                         break;
 846 #endif
 847                 case Opt_err:
 848                         btrfs_info(info, "unrecognized mount option '%s'", p);
 849                         ret = -EINVAL;
 850                         goto out;
 851                 default:
 852                         break;
 853                 }
 854         }
 855 check:
 856         /*
 857          * Extra check for current option against current flag
 858          */
 859         if (btrfs_test_opt(info, NOLOGREPLAY) && !(new_flags & SB_RDONLY)) {
 860                 btrfs_err(info,
 861                           "nologreplay must be used with ro mount option");
 862                 ret = -EINVAL;
 863         }
 864 out:
 865         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) &&
 866             !btrfs_test_opt(info, FREE_SPACE_TREE) &&
 867             !btrfs_test_opt(info, CLEAR_CACHE)) {
 868                 btrfs_err(info, "cannot disable free space tree");
 869                 ret = -EINVAL;
 870
 871         }
 872         if (!ret && btrfs_test_opt(info, SPACE_CACHE))
 873                 btrfs_info(info, "disk space caching is enabled");
 874         if (!ret && btrfs_test_opt(info, FREE_SPACE_TREE))
 875                 btrfs_info(info, "using free space tree");
 876         return ret;
 877 }
 878
 879 /*
 880  * Parse mount options that are required early in the mount process.
 881  *
 882  * All other options will be parsed on much later in the mount process and
 883  * only when we need to allocate a new super block.
 884  */
 885 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 886                 void *holder, struct btrfs_fs_devices **fs_devices)
 887 {
 888         substring_t args[MAX_OPT_ARGS];
 889         char *device_name, *opts, *orig, *p;
 890         int error = 0;
 891
 892         if (!options)
 893                 return 0;
 894
 895         /*
 896          * strsep changes the string, duplicate it because btrfs_parse_options
 897          * gets called later
 898          */
 899         opts = kstrdup(options, GFP_KERNEL);
 900         if (!opts)
 901                 return -ENOMEM;
 902         orig = opts;
 903
 904         while ((p = strsep(&opts, ",")) != NULL) {
 905                 int token;
 906
 907                 if (!*p)
 908                         continue;
 909
 910                 token = match_token(p, tokens, args);
 911                 if (token == Opt_device) {
 912                         device_name = match_strdup(&args[0]);
 913                         if (!device_name) {
 914                                 error = -ENOMEM;
 915                                 goto out;
 916                         }
 917                         error = btrfs_scan_one_device(device_name,
 918                                         flags, holder, fs_devices);
 919                         kfree(device_name);
 920                         if (error)
 921                                 goto out;
 922                 }
 923         }
 924
 925 out:
 926         kfree(orig);
 927         return error;
 928 }
 929
 930 /*
 931  * Parse mount options that are related to subvolume id
 932  *
 933  * The value is later passed to mount_subvol()
 934  */
 935 static int btrfs_parse_subvol_options(const char *options, fmode_t flags,
 936                 char **subvol_name, u64 *subvol_objectid)
 937 {
 938         substring_t args[MAX_OPT_ARGS];
 939         char *opts, *orig, *p;
 940         int error = 0;
 941         u64 subvolid;
 942
 943         if (!options)
 944                 return 0;
 945
 946         /*
 947          * strsep changes the string, duplicate it because
 948          * btrfs_parse_early_options gets called later
 949          */
 950         opts = kstrdup(options, GFP_KERNEL);
 951         if (!opts)
 952                 return -ENOMEM;
 953         orig = opts;
 954
 955         while ((p = strsep(&opts, ",")) != NULL) {
 956                 int token;
 957                 if (!*p)
 958                         continue;
 959
 960                 token = match_token(p, tokens, args);
 961                 switch (token) {
 962                 case Opt_subvol:
 963                         kfree(*subvol_name);
 964                         *subvol_name = match_strdup(&args[0]);
 965                         if (!*subvol_name) {
 966                                 error = -ENOMEM;
 967                                 goto out;
 968                         }
 969                         break;
 970                 case Opt_subvolid:
 971                         error = match_u64(&args[0], &subvolid);
 972                         if (error)
 973                                 goto out;
 974
 975                         /* we want the original fs_tree */
 976                         if (subvolid == 0)
 977                                 subvolid = BTRFS_FS_TREE_OBJECTID;
 978
 979                         *subvol_objectid = subvolid;
 980                         break;
 981                 case Opt_subvolrootid:
 982                         pr_warn("BTRFS: 'subvolrootid' mount option is deprecated and has no effect\n");
 983                         break;
 984                 default:
 985                         break;
 986                 }
 987         }
 988
 989 out:
 990         kfree(orig);
 991         return error;
 992 }
 993
 994 static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 995                                            u64 subvol_objectid)
 996 {
 997         struct btrfs_root *root = fs_info->tree_root;
 998         struct btrfs_root *fs_root;
 999         struct btrfs_root_ref *root_ref;
1000         struct btrfs_inode_ref *inode_ref;
1001         struct btrfs_key key;
1002         struct btrfs_path *path = NULL;
1003         char *name = NULL, *ptr;
1004         u64 dirid;
1005         int len;
1006         int ret;
1007
1008         path = btrfs_alloc_path();
1009         if (!path) {
1010                 ret = -ENOMEM;
1011                 goto err;
1012         }
1013         path->leave_spinning = 1;
1014
1015         name = kmalloc(PATH_MAX, GFP_KERNEL);
1016         if (!name) {
1017                 ret = -ENOMEM;
1018                 goto err;
1019         }
1020         ptr = name + PATH_MAX - 1;
1021         ptr[0] = '\0';
1022
1023         /*
1024          * Walk up the subvolume trees in the tree of tree roots by root
1025          * backrefs until we hit the top-level subvolume.
1026          */
1027         while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
1028                 key.objectid = subvol_objectid;
1029                 key.type = BTRFS_ROOT_BACKREF_KEY;
1030                 key.offset = (u64)-1;
1031
1032                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1033                 if (ret < 0) {
1034                         goto err;
1035                 } else if (ret > 0) {
1036                         ret = btrfs_previous_item(root, path, subvol_objectid,
1037                                                   BTRFS_ROOT_BACKREF_KEY);
1038                         if (ret < 0) {
1039                                 goto err;
1040                         } else if (ret > 0) {
1041                                 ret = -ENOENT;
1042                                 goto err;
1043                         }
1044                 }
1045
1046                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1047                 subvol_objectid = key.offset;
1048
1049                 root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1050                                           struct btrfs_root_ref);
1051                 len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
1052                 ptr -= len + 1;
1053                 if (ptr < name) {
1054                         ret = -ENAMETOOLONG;
1055                         goto err;
1056                 }
1057                 read_extent_buffer(path->nodes[0], ptr + 1,
1058                                    (unsigned long)(root_ref + 1), len);
1059                 ptr[0] = '/';
1060                 dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
1061                 btrfs_release_path(path);
1062
1063                 key.objectid = subvol_objectid;
1064                 key.type = BTRFS_ROOT_ITEM_KEY;
1065                 key.offset = (u64)-1;
1066                 fs_root = btrfs_read_fs_root_no_name(fs_info, &key);
1067                 if (IS_ERR(fs_root)) {
1068                         ret = PTR_ERR(fs_root);
1069                         goto err;
1070                 }
1071
1072                 /*
1073                  * Walk up the filesystem tree by inode refs until we hit the
1074                  * root directory.
1075                  */
1076                 while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
1077                         key.objectid = dirid;
1078                         key.type = BTRFS_INODE_REF_KEY;
1079                         key.offset = (u64)-1;
1080
1081                         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1082                         if (ret < 0) {
1083                                 goto err;
1084                         } else if (ret > 0) {
1085                                 ret = btrfs_previous_item(fs_root, path, dirid,
1086                                                           BTRFS_INODE_REF_KEY);
1087                                 if (ret < 0) {
1088                                         goto err;
1089                                 } else if (ret > 0) {
1090                                         ret = -ENOENT;
1091                                         goto err;
1092                                 }
1093                         }
1094
1095                         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1096                         dirid = key.offset;
1097
1098                         inode_ref = btrfs_item_ptr(path->nodes[0],
1099                                                    path->slots[0],
1100                                                    struct btrfs_inode_ref);
1101                         len = btrfs_inode_ref_name_len(path->nodes[0],
1102                                                        inode_ref);
1103                         ptr -= len + 1;
1104                         if (ptr < name) {
1105                                 ret = -ENAMETOOLONG;
1106                                 goto err;
1107                         }
1108                         read_extent_buffer(path->nodes[0], ptr + 1,
1109                                            (unsigned long)(inode_ref + 1), len);
1110                         ptr[0] = '/';
1111                         btrfs_release_path(path);
1112                 }
1113         }
1114
1115         btrfs_free_path(path);
1116         if (ptr == name + PATH_MAX - 1) {
1117                 name[0] = '/';
1118                 name[1] = '\0';
1119         } else {
1120                 memmove(name, ptr, name + PATH_MAX - ptr);
1121         }
1122         return name;
1123
1124 err:
1125         btrfs_free_path(path);
1126         kfree(name);
1127         return ERR_PTR(ret);
1128 }
1129
1130 static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
1131 {
1132         struct btrfs_root *root = fs_info->tree_root;
1133         struct btrfs_dir_item *di;
1134         struct btrfs_path *path;
1135         struct btrfs_key location;
1136         u64 dir_id;
1137
1138         path = btrfs_alloc_path();
1139         if (!path)
1140                 return -ENOMEM;
1141         path->leave_spinning = 1;
1142
1143         /*
1144          * Find the "default" dir item which points to the root item that we
1145          * will mount by default if we haven't been given a specific subvolume
1146          * to mount.
1147          */
1148         dir_id = btrfs_super_root_dir(fs_info->super_copy);
1149         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
1150         if (IS_ERR(di)) {
1151                 btrfs_free_path(path);
1152                 return PTR_ERR(di);
1153         }
1154         if (!di) {
1155                 /*
1156                  * Ok the default dir item isn't there.  This is weird since
1157                  * it's always been there, but don't freak out, just try and
1158                  * mount the top-level subvolume.
1159                  */
1160                 btrfs_free_path(path);
1161                 *objectid = BTRFS_FS_TREE_OBJECTID;
1162                 return 0;
1163         }
1164
1165         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
1166         btrfs_free_path(path);
1167         *objectid = location.objectid;
1168         return 0;
1169 }
1170
1171 static int btrfs_fill_super(struct super_block *sb,
1172                             struct btrfs_fs_devices *fs_devices,
1173                             void *data)
1174 {
1175         struct inode *inode;
1176         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1177         struct btrfs_key key;
1178         int err;
1179
1180         sb->s_maxbytes = MAX_LFS_FILESIZE;
1181         sb->s_magic = BTRFS_SUPER_MAGIC;
1182         sb->s_op = &btrfs_super_ops;
1183         sb->s_d_op = &btrfs_dentry_operations;
1184         sb->s_export_op = &btrfs_export_ops;
1185         sb->s_xattr = btrfs_xattr_handlers;
1186         sb->s_time_gran = 1;
1187 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
1188         sb->s_flags |= SB_POSIXACL;
1189 #endif
1190         sb->s_flags |= SB_I_VERSION;
1191         sb->s_iflags |= SB_I_CGROUPWB;
1192
1193         err = super_setup_bdi(sb);
1194         if (err) {
1195                 btrfs_err(fs_info, "super_setup_bdi failed");
1196                 return err;
1197         }
1198
1199         err = open_ctree(sb, fs_devices, (char *)data);
1200         if (err) {
1201                 btrfs_err(fs_info, "open_ctree failed");
1202                 return err;
1203         }
1204
1205         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
1206         key.type = BTRFS_INODE_ITEM_KEY;
1207         key.offset = 0;
1208         inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
1209         if (IS_ERR(inode)) {
1210                 err = PTR_ERR(inode);
1211                 goto fail_close;
1212         }
1213
1214         sb->s_root = d_make_root(inode);
1215         if (!sb->s_root) {
1216                 err = -ENOMEM;
1217                 goto fail_close;
1218         }
1219
1220         cleancache_init_fs(sb);
1221         sb->s_flags |= SB_ACTIVE;
1222         return 0;
1223
1224 fail_close:
1225         close_ctree(fs_info);
1226         return err;
1227 }
1228
1229 int btrfs_sync_fs(struct super_block *sb, int wait)
1230 {
1231         struct btrfs_trans_handle *trans;
1232         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1233         struct btrfs_root *root = fs_info->tree_root;
1234
1235         trace_btrfs_sync_fs(fs_info, wait);
1236
1237         if (!wait) {
1238                 filemap_flush(fs_info->btree_inode->i_mapping);
1239                 return 0;
1240         }
1241
1242         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
1243
1244         trans = btrfs_attach_transaction_barrier(root);
1245         if (IS_ERR(trans)) {
1246                 /* no transaction, don't bother */
1247                 if (PTR_ERR(trans) == -ENOENT) {
1248                         /*
1249                          * Exit unless we have some pending changes
1250                          * that need to go through commit
1251                          */
1252                         if (fs_info->pending_changes == 0)
1253                                 return 0;
1254                         /*
1255                          * A non-blocking test if the fs is frozen. We must not
1256                          * start a new transaction here otherwise a deadlock
1257                          * happens. The pending operations are delayed to the
1258                          * next commit after thawing.
1259                          */
1260                         if (sb_start_write_trylock(sb))
1261                                 sb_end_write(sb);
1262                         else
1263                                 return 0;
1264                         trans = btrfs_start_transaction(root, 0);
1265                 }
1266                 if (IS_ERR(trans))
1267                         return PTR_ERR(trans);
1268         }
1269         return btrfs_commit_transaction(trans);
1270 }
1271
1272 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1273 {
1274         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1275         const char *compress_type;
1276
1277         if (btrfs_test_opt(info, DEGRADED))
1278                 seq_puts(seq, ",degraded");
1279         if (btrfs_test_opt(info, NODATASUM))
1280                 seq_puts(seq, ",nodatasum");
1281         if (btrfs_test_opt(info, NODATACOW))
1282                 seq_puts(seq, ",nodatacow");
1283         if (btrfs_test_opt(info, NOBARRIER))
1284                 seq_puts(seq, ",nobarrier");
1285         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1286                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
1287         if (info->thread_pool_size !=  min_t(unsigned long,
1288                                              num_online_cpus() + 2, 8))
1289                 seq_printf(seq, ",thread_pool=%u", info->thread_pool_size);
1290         if (btrfs_test_opt(info, COMPRESS)) {
1291                 compress_type = btrfs_compress_type2str(info->compress_type);
1292                 if (btrfs_test_opt(info, FORCE_COMPRESS))
1293                         seq_printf(seq, ",compress-force=%s", compress_type);
1294                 else
1295                         seq_printf(seq, ",compress=%s", compress_type);
1296                 if (info->compress_level)
1297                         seq_printf(seq, ":%d", info->compress_level);
1298         }
1299         if (btrfs_test_opt(info, NOSSD))
1300                 seq_puts(seq, ",nossd");
1301         if (btrfs_test_opt(info, SSD_SPREAD))
1302                 seq_puts(seq, ",ssd_spread");
1303         else if (btrfs_test_opt(info, SSD))
1304                 seq_puts(seq, ",ssd");
1305         if (btrfs_test_opt(info, NOTREELOG))
1306                 seq_puts(seq, ",notreelog");
1307         if (btrfs_test_opt(info, NOLOGREPLAY))
1308                 seq_puts(seq, ",nologreplay");
1309         if (btrfs_test_opt(info, FLUSHONCOMMIT))
1310                 seq_puts(seq, ",flushoncommit");
1311         if (btrfs_test_opt(info, DISCARD))
1312                 seq_puts(seq, ",discard");
1313         if (!(info->sb->s_flags & SB_POSIXACL))
1314                 seq_puts(seq, ",noacl");
1315         if (btrfs_test_opt(info, SPACE_CACHE))
1316                 seq_puts(seq, ",space_cache");
1317         else if (btrfs_test_opt(info, FREE_SPACE_TREE))
1318                 seq_puts(seq, ",space_cache=v2");
1319         else
1320                 seq_puts(seq, ",nospace_cache");
1321         if (btrfs_test_opt(info, RESCAN_UUID_TREE))
1322                 seq_puts(seq, ",rescan_uuid_tree");
1323         if (btrfs_test_opt(info, CLEAR_CACHE))
1324                 seq_puts(seq, ",clear_cache");
1325         if (btrfs_test_opt(info, USER_SUBVOL_RM_ALLOWED))
1326                 seq_puts(seq, ",user_subvol_rm_allowed");
1327         if (btrfs_test_opt(info, ENOSPC_DEBUG))
1328                 seq_puts(seq, ",enospc_debug");
1329         if (btrfs_test_opt(info, AUTO_DEFRAG))
1330                 seq_puts(seq, ",autodefrag");
1331         if (btrfs_test_opt(info, INODE_MAP_CACHE))
1332                 seq_puts(seq, ",inode_cache");
1333         if (btrfs_test_opt(info, SKIP_BALANCE))
1334                 seq_puts(seq, ",skip_balance");
1335 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1336         if (btrfs_test_opt(info, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
1337                 seq_puts(seq, ",check_int_data");
1338         else if (btrfs_test_opt(info, CHECK_INTEGRITY))
1339                 seq_puts(seq, ",check_int");
1340         if (info->check_integrity_print_mask)
1341                 seq_printf(seq, ",check_int_print_mask=%d",
1342                                 info->check_integrity_print_mask);
1343 #endif
1344         if (info->metadata_ratio)
1345                 seq_printf(seq, ",metadata_ratio=%u", info->metadata_ratio);
1346         if (btrfs_test_opt(info, PANIC_ON_FATAL_ERROR))
1347                 seq_puts(seq, ",fatal_errors=panic");
1348         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1349                 seq_printf(seq, ",commit=%u", info->commit_interval);
1350 #ifdef CONFIG_BTRFS_DEBUG
1351         if (btrfs_test_opt(info, FRAGMENT_DATA))
1352                 seq_puts(seq, ",fragment=data");
1353         if (btrfs_test_opt(info, FRAGMENT_METADATA))
1354                 seq_puts(seq, ",fragment=metadata");
1355 #endif
1356         if (btrfs_test_opt(info, REF_VERIFY))
1357                 seq_puts(seq, ",ref_verify");
1358         seq_printf(seq, ",subvolid=%llu",
1359                   BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1360         seq_puts(seq, ",subvol=");
1361         seq_dentry(seq, dentry, " \t\n\\");
1362         return 0;
1363 }
1364
1365 static int btrfs_test_super(struct super_block *s, void *data)
1366 {
1367         struct btrfs_fs_info *p = data;
1368         struct btrfs_fs_info *fs_info = btrfs_sb(s);
1369
1370         return fs_info->fs_devices == p->fs_devices;
1371 }
1372
1373 static int btrfs_set_super(struct super_block *s, void *data)
1374 {
1375         int err = set_anon_super(s, data);
1376         if (!err)
1377                 s->s_fs_info = data;
1378         return err;
1379 }
1380
1381 /*
1382  * subvolumes are identified by ino 256
1383  */
1384 static inline int is_subvolume_inode(struct inode *inode)
1385 {
1386         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1387                 return 1;
1388         return 0;
1389 }
1390
1391 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
1392                                    const char *device_name, struct vfsmount *mnt)
1393 {
1394         struct dentry *root;
1395         int ret;
1396
1397         if (!subvol_name) {
1398                 if (!subvol_objectid) {
1399                         ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
1400                                                           &subvol_objectid);
1401                         if (ret) {
1402                                 root = ERR_PTR(ret);
1403                                 goto out;
1404                         }
1405                 }
1406                 subvol_name = get_subvol_name_from_objectid(btrfs_sb(mnt->mnt_sb),
1407                                                             subvol_objectid);
1408                 if (IS_ERR(subvol_name)) {
1409                         root = ERR_CAST(subvol_name);
1410                         subvol_name = NULL;
1411                         goto out;
1412                 }
1413
1414         }
1415
1416         root = mount_subtree(mnt, subvol_name);
1417         /* mount_subtree() drops our reference on the vfsmount. */
1418         mnt = NULL;
1419
1420         if (!IS_ERR(root)) {
1421                 struct super_block *s = root->d_sb;
1422                 struct btrfs_fs_info *fs_info = btrfs_sb(s);
1423                 struct inode *root_inode = d_inode(root);
1424                 u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
1425
1426                 ret = 0;
1427                 if (!is_subvolume_inode(root_inode)) {
1428                         btrfs_err(fs_info, "'%s' is not a valid subvolume",
1429                                subvol_name);
1430                         ret = -EINVAL;
1431                 }
1432                 if (subvol_objectid && root_objectid != subvol_objectid) {
1433                         /*
1434                          * This will also catch a race condition where a
1435                          * subvolume which was passed by ID is renamed and
1436                          * another subvolume is renamed over the old location.
1437                          */
1438                         btrfs_err(fs_info,
1439                                   "subvol '%s' does not match subvolid %llu",
1440                                   subvol_name, subvol_objectid);
1441                         ret = -EINVAL;
1442                 }
1443                 if (ret) {
1444                         dput(root);
1445                         root = ERR_PTR(ret);
1446                         deactivate_locked_super(s);
1447                 }
1448         }
1449
1450 out:
1451         mntput(mnt);
1452         kfree(subvol_name);
1453         return root;
1454 }
1455
1456 static int parse_security_options(char *orig_opts,
1457                                   struct security_mnt_opts *sec_opts)
1458 {
1459         char *secdata = NULL;
1460         int ret = 0;
1461
1462         secdata = alloc_secdata();
1463         if (!secdata)
1464                 return -ENOMEM;
1465         ret = security_sb_copy_data(orig_opts, secdata);
1466         if (ret) {
1467                 free_secdata(secdata);
1468                 return ret;
1469         }
1470         ret = security_sb_parse_opts_str(secdata, sec_opts);
1471         free_secdata(secdata);
1472         return ret;
1473 }
1474
1475 static int setup_security_options(struct btrfs_fs_info *fs_info,
1476                                   struct super_block *sb,
1477                                   struct security_mnt_opts *sec_opts)
1478 {
1479         int ret = 0;
1480
1481         /*
1482          * Call security_sb_set_mnt_opts() to check whether new sec_opts
1483          * is valid.
1484          */
1485         ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
1486         if (ret)
1487                 return ret;
1488
1489 #ifdef CONFIG_SECURITY
1490         if (!fs_info->security_opts.num_mnt_opts) {
1491                 /* first time security setup, copy sec_opts to fs_info */
1492                 memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts));
1493         } else {
1494                 /*
1495                  * Since SELinux (the only one supporting security_mnt_opts)
1496                  * does NOT support changing context during remount/mount of
1497                  * the same sb, this must be the same or part of the same
1498                  * security options, just free it.
1499                  */
1500                 security_free_mnt_opts(sec_opts);
1501         }
1502 #endif
1503         return ret;
1504 }
1505
1506 /*
1507  * Find a superblock for the given device / mount point.
1508  *
1509  * Note: This is based on mount_bdev from fs/super.c with a few additions
1510  *       for multiple device setup.  Make sure to keep it in sync.
1511  */
1512 static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
1513                 int flags, const char *device_name, void *data)
1514 {
1515         struct block_device *bdev = NULL;
1516         struct super_block *s;
1517         struct btrfs_fs_devices *fs_devices = NULL;
1518         struct btrfs_fs_info *fs_info = NULL;
1519         struct security_mnt_opts new_sec_opts;
1520         fmode_t mode = FMODE_READ;
1521         int error = 0;
1522
1523         if (!(flags & SB_RDONLY))
1524                 mode |= FMODE_WRITE;
1525
1526         error = btrfs_parse_early_options(data, mode, fs_type,
1527                                           &fs_devices);
1528         if (error) {
1529                 return ERR_PTR(error);
1530         }
1531
1532         security_init_mnt_opts(&new_sec_opts);
1533         if (data) {
1534                 error = parse_security_options(data, &new_sec_opts);
1535                 if (error)
1536                         return ERR_PTR(error);
1537         }
1538
1539         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1540         if (error)
1541                 goto error_sec_opts;
1542
1543         /*
1544          * Setup a dummy root and fs_info for test/set super.  This is because
1545          * we don't actually fill this stuff out until open_ctree, but we need
1546          * it for searching for existing supers, so this lets us do that and
1547          * then open_ctree will properly initialize everything later.
1548          */
1549         fs_info = kvzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
1550         if (!fs_info) {
1551                 error = -ENOMEM;
1552                 goto error_sec_opts;
1553         }
1554
1555         fs_info->fs_devices = fs_devices;
1556
1557         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1558         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1559         security_init_mnt_opts(&fs_info->security_opts);
1560         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1561                 error = -ENOMEM;
1562                 goto error_fs_info;
1563         }
1564
1565         error = btrfs_open_devices(fs_devices, mode, fs_type);
1566         if (error)
1567                 goto error_fs_info;
1568
1569         if (!(flags & SB_RDONLY) && fs_devices->rw_devices == 0) {
1570                 error = -EACCES;
1571                 goto error_close_devices;
1572         }
1573
1574         bdev = fs_devices->latest_bdev;
1575         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | SB_NOSEC,
1576                  fs_info);
1577         if (IS_ERR(s)) {
1578                 error = PTR_ERR(s);
1579                 goto error_close_devices;
1580         }
1581
1582         if (s->s_root) {
1583                 btrfs_close_devices(fs_devices);
1584                 free_fs_info(fs_info);
1585                 if ((flags ^ s->s_flags) & SB_RDONLY)
1586                         error = -EBUSY;
1587         } else {
1588                 snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
1589                 btrfs_sb(s)->bdev_holder = fs_type;
1590                 error = btrfs_fill_super(s, fs_devices, data);
1591         }
1592         if (error) {
1593                 deactivate_locked_super(s);
1594                 goto error_sec_opts;
1595         }
1596
1597         fs_info = btrfs_sb(s);
1598         error = setup_security_options(fs_info, s, &new_sec_opts);
1599         if (error) {
1600                 deactivate_locked_super(s);
1601                 goto error_sec_opts;
1602         }
1603
1604         return dget(s->s_root);
1605
1606 error_close_devices:
1607         btrfs_close_devices(fs_devices);
1608 error_fs_info:
1609         free_fs_info(fs_info);
1610 error_sec_opts:
1611         security_free_mnt_opts(&new_sec_opts);
1612         return ERR_PTR(error);
1613 }
1614
1615 /*
1616  * Mount function which is called by VFS layer.
1617  *
1618  * In order to allow mounting a subvolume directly, btrfs uses mount_subtree()
1619  * which needs vfsmount* of device's root (/).  This means device's root has to
1620  * be mounted internally in any case.
1621  *
1622  * Operation flow:
1623  *   1. Parse subvol id related options for later use in mount_subvol().
1624  *
1625  *   2. Mount device's root (/) by calling vfs_kern_mount().
1626  *
1627  *      NOTE: vfs_kern_mount() is used by VFS to call btrfs_mount() in the
1628  *      first place. In order to avoid calling btrfs_mount() again, we use
1629  *      different file_system_type which is not registered to VFS by
1630  *      register_filesystem() (btrfs_root_fs_type). As a result,
1631  *      btrfs_mount_root() is called. The return value will be used by
1632  *      mount_subtree() in mount_subvol().
1633  *
1634  *   3. Call mount_subvol() to get the dentry of subvolume. Since there is
1635  *      "btrfs subvolume set-default", mount_subvol() is called always.
1636  */
1637 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1638                 const char *device_name, void *data)
1639 {
1640         struct vfsmount *mnt_root;
1641         struct dentry *root;
1642         fmode_t mode = FMODE_READ;
1643         char *subvol_name = NULL;
1644         u64 subvol_objectid = 0;
1645         int error = 0;
1646
1647         if (!(flags & SB_RDONLY))
1648                 mode |= FMODE_WRITE;
1649
1650         error = btrfs_parse_subvol_options(data, mode,
1651                                           &subvol_name, &subvol_objectid);
1652         if (error) {
1653                 kfree(subvol_name);
1654                 return ERR_PTR(error);
1655         }
1656
1657         /* mount device's root (/) */
1658         mnt_root = vfs_kern_mount(&btrfs_root_fs_type, flags, device_name, data);
1659         if (PTR_ERR_OR_ZERO(mnt_root) == -EBUSY) {
1660                 if (flags & SB_RDONLY) {
1661                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1662                                 flags & ~SB_RDONLY, device_name, data);
1663                 } else {
1664                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1665                                 flags | SB_RDONLY, device_name, data);
1666                         if (IS_ERR(mnt_root)) {
1667                                 root = ERR_CAST(mnt_root);
1668                                 goto out;
1669                         }
1670
1671                         down_write(&mnt_root->mnt_sb->s_umount);
1672                         error = btrfs_remount(mnt_root->mnt_sb, &flags, NULL);
1673                         up_write(&mnt_root->mnt_sb->s_umount);
1674                         if (error < 0) {
1675                                 root = ERR_PTR(error);
1676                                 mntput(mnt_root);
1677                                 goto out;
1678                         }
1679                 }
1680         }
1681         if (IS_ERR(mnt_root)) {
1682                 root = ERR_CAST(mnt_root);
1683                 goto out;
1684         }
1685
1686         /* mount_subvol() will free subvol_name and mnt_root */
1687         root = mount_subvol(subvol_name, subvol_objectid, device_name, mnt_root);
1688
1689 out:
1690         return root;
1691 }
1692
1693 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1694                                      u32 new_pool_size, u32 old_pool_size)
1695 {
1696         if (new_pool_size == old_pool_size)
1697                 return;
1698
1699         fs_info->thread_pool_size = new_pool_size;
1700
1701         btrfs_info(fs_info, "resize thread pool %d -> %d",
1702                old_pool_size, new_pool_size);
1703
1704         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1705         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1706         btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);
1707         btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1708         btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
1709         btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
1710         btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
1711                                 new_pool_size);
1712         btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1713         btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1714         btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1715         btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
1716         btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
1717                                 new_pool_size);
1718 }
1719
1720 static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
1721 {
1722         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1723 }
1724
1725 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1726                                        unsigned long old_opts, int flags)
1727 {
1728         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1729             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1730              (flags & SB_RDONLY))) {
1731                 /* wait for any defraggers to finish */
1732                 wait_event(fs_info->transaction_wait,
1733                            (atomic_read(&fs_info->defrag_running) == 0));
1734                 if (flags & SB_RDONLY)
1735                         sync_filesystem(fs_info->sb);
1736         }
1737 }
1738
1739 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1740                                          unsigned long old_opts)
1741 {
1742         /*
1743          * We need to cleanup all defragable inodes if the autodefragment is
1744          * close or the filesystem is read only.
1745          */
1746         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1747             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) || sb_rdonly(fs_info->sb))) {
1748                 btrfs_cleanup_defrag_inodes(fs_info);
1749         }
1750
1751         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1752 }
1753
1754 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1755 {
1756         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1757         struct btrfs_root *root = fs_info->tree_root;
1758         unsigned old_flags = sb->s_flags;
1759         unsigned long old_opts = fs_info->mount_opt;
1760         unsigned long old_compress_type = fs_info->compress_type;
1761         u64 old_max_inline = fs_info->max_inline;
1762         u32 old_thread_pool_size = fs_info->thread_pool_size;
1763         u32 old_metadata_ratio = fs_info->metadata_ratio;
1764         int ret;
1765
1766         sync_filesystem(sb);
1767         btrfs_remount_prepare(fs_info);
1768
1769         if (data) {
1770                 struct security_mnt_opts new_sec_opts;
1771
1772                 security_init_mnt_opts(&new_sec_opts);
1773                 ret = parse_security_options(data, &new_sec_opts);
1774                 if (ret)
1775                         goto restore;
1776                 ret = setup_security_options(fs_info, sb,
1777                                              &new_sec_opts);
1778                 if (ret) {
1779                         security_free_mnt_opts(&new_sec_opts);
1780                         goto restore;
1781                 }
1782         }
1783
1784         ret = btrfs_parse_options(fs_info, data, *flags);
1785         if (ret) {
1786                 ret = -EINVAL;
1787                 goto restore;
1788         }
1789
1790         btrfs_remount_begin(fs_info, old_opts, *flags);
1791         btrfs_resize_thread_pool(fs_info,
1792                 fs_info->thread_pool_size, old_thread_pool_size);
1793
1794         if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
1795                 goto out;
1796
1797         if (*flags & SB_RDONLY) {
1798                 /*
1799                  * this also happens on 'umount -rf' or on shutdown, when
1800                  * the filesystem is busy.
1801                  */
1802                 cancel_work_sync(&fs_info->async_reclaim_work);
1803
1804                 /* wait for the uuid_scan task to finish */
1805                 down(&fs_info->uuid_tree_rescan_sem);
1806                 /* avoid complains from lockdep et al. */
1807                 up(&fs_info->uuid_tree_rescan_sem);
1808
1809                 sb->s_flags |= SB_RDONLY;
1810
1811                 /*
1812                  * Setting SB_RDONLY will put the cleaner thread to
1813                  * sleep at the next loop if it's already active.
1814                  * If it's already asleep, we'll leave unused block
1815                  * groups on disk until we're mounted read-write again
1816                  * unless we clean them up here.
1817                  */
1818                 btrfs_delete_unused_bgs(fs_info);
1819
1820                 btrfs_dev_replace_suspend_for_unmount(fs_info);
1821                 btrfs_scrub_cancel(fs_info);
1822                 btrfs_pause_balance(fs_info);
1823
1824                 ret = btrfs_commit_super(fs_info);
1825                 if (ret)
1826                         goto restore;
1827         } else {
1828                 if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
1829                         btrfs_err(fs_info,
1830                                 "Remounting read-write after error is not allowed");
1831                         ret = -EINVAL;
1832                         goto restore;
1833                 }
1834                 if (fs_info->fs_devices->rw_devices == 0) {
1835                         ret = -EACCES;
1836                         goto restore;
1837                 }
1838
1839                 if (!btrfs_check_rw_degradable(fs_info, NULL)) {
1840                         btrfs_warn(fs_info,
1841                                 "too many missing devices, writeable remount is not allowed");
1842                         ret = -EACCES;
1843                         goto restore;
1844                 }
1845
1846                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1847                         ret = -EINVAL;
1848                         goto restore;
1849                 }
1850
1851                 ret = btrfs_cleanup_fs_roots(fs_info);
1852                 if (ret)
1853                         goto restore;
1854
1855                 /* recover relocation */
1856                 mutex_lock(&fs_info->cleaner_mutex);
1857                 ret = btrfs_recover_relocation(root);
1858                 mutex_unlock(&fs_info->cleaner_mutex);
1859                 if (ret)
1860                         goto restore;
1861
1862                 ret = btrfs_resume_balance_async(fs_info);
1863                 if (ret)
1864                         goto restore;
1865
1866                 ret = btrfs_resume_dev_replace_async(fs_info);
1867                 if (ret) {
1868                         btrfs_warn(fs_info, "failed to resume dev_replace");
1869                         goto restore;
1870                 }
1871
1872                 btrfs_qgroup_rescan_resume(fs_info);
1873
1874                 if (!fs_info->uuid_root) {
1875                         btrfs_info(fs_info, "creating UUID tree");
1876                         ret = btrfs_create_uuid_tree(fs_info);
1877                         if (ret) {
1878                                 btrfs_warn(fs_info,
1879                                            "failed to create the UUID tree %d",
1880                                            ret);
1881                                 goto restore;
1882                         }
1883                 }
1884                 sb->s_flags &= ~SB_RDONLY;
1885
1886                 set_bit(BTRFS_FS_OPEN, &fs_info->flags);
1887         }
1888 out:
1889         wake_up_process(fs_info->transaction_kthread);
1890         btrfs_remount_cleanup(fs_info, old_opts);
1891         return 0;
1892
1893 restore:
1894         /* We've hit an error - don't reset SB_RDONLY */
1895         if (sb_rdonly(sb))
1896                 old_flags |= SB_RDONLY;
1897         sb->s_flags = old_flags;
1898         fs_info->mount_opt = old_opts;
1899         fs_info->compress_type = old_compress_type;
1900         fs_info->max_inline = old_max_inline;
1901         btrfs_resize_thread_pool(fs_info,
1902                 old_thread_pool_size, fs_info->thread_pool_size);
1903         fs_info->metadata_ratio = old_metadata_ratio;
1904         btrfs_remount_cleanup(fs_info, old_opts);
1905         return ret;
1906 }
1907
1908 /* Used to sort the devices by max_avail(descending sort) */
1909 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1910                                        const void *dev_info2)
1911 {
1912         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1913             ((struct btrfs_device_info *)dev_info2)->max_avail)
1914                 return -1;
1915         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1916                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1917                 return 1;
1918         else
1919         return 0;
1920 }
1921
1922 /*
1923  * sort the devices by max_avail, in which max free extent size of each device
1924  * is stored.(Descending Sort)
1925  */
1926 static inline void btrfs_descending_sort_devices(
1927                                         struct btrfs_device_info *devices,
1928                                         size_t nr_devices)
1929 {
1930         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1931              btrfs_cmp_device_free_bytes, NULL);
1932 }
1933
1934 /*
1935  * The helper to calc the free space on the devices that can be used to store
1936  * file data.
1937  */
1938 static int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
1939                                        u64 *free_bytes)
1940 {
1941         struct btrfs_device_info *devices_info;
1942         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1943         struct btrfs_device *device;
1944         u64 skip_space;
1945         u64 type;
1946         u64 avail_space;
1947         u64 min_stripe_size;
1948         int min_stripes = 1, num_stripes = 1;
1949         int i = 0, nr_devices;
1950
1951         /*
1952          * We aren't under the device list lock, so this is racy-ish, but good
1953          * enough for our purposes.
1954          */
1955         nr_devices = fs_info->fs_devices->open_devices;
1956         if (!nr_devices) {
1957                 smp_mb();
1958                 nr_devices = fs_info->fs_devices->open_devices;
1959                 ASSERT(nr_devices);
1960                 if (!nr_devices) {
1961                         *free_bytes = 0;
1962                         return 0;
1963                 }
1964         }
1965
1966         devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
1967                                GFP_KERNEL);
1968         if (!devices_info)
1969                 return -ENOMEM;
1970
1971         /* calc min stripe number for data space allocation */
1972         type = btrfs_data_alloc_profile(fs_info);
1973         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1974                 min_stripes = 2;
1975                 num_stripes = nr_devices;
1976         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1977                 min_stripes = 2;
1978                 num_stripes = 2;
1979         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1980                 min_stripes = 4;
1981                 num_stripes = 4;
1982         }
1983
1984         if (type & BTRFS_BLOCK_GROUP_DUP)
1985                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1986         else
1987                 min_stripe_size = BTRFS_STRIPE_LEN;
1988
1989         rcu_read_lock();
1990         list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
1991                 if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
1992                                                 &device->dev_state) ||
1993                     !device->bdev ||
1994                     test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
1995                         continue;
1996
1997                 if (i >= nr_devices)
1998                         break;
1999
2000                 avail_space = device->total_bytes - device->bytes_used;
2001
2002                 /* align with stripe_len */
2003                 avail_space = div_u64(avail_space, BTRFS_STRIPE_LEN);
2004                 avail_space *= BTRFS_STRIPE_LEN;
2005
2006                 /*
2007                  * In order to avoid overwriting the superblock on the drive,
2008                  * btrfs starts at an offset of at least 1MB when doing chunk
2009                  * allocation.
2010                  */
2011                 skip_space = SZ_1M;
2012
2013                 /*
2014                  * we can use the free space in [0, skip_space - 1], subtract
2015                  * it from the total.
2016                  */
2017                 if (avail_space && avail_space >= skip_space)
2018                         avail_space -= skip_space;
2019                 else
2020                         avail_space = 0;
2021
2022                 if (avail_space < min_stripe_size)
2023                         continue;
2024
2025                 devices_info[i].dev = device;
2026                 devices_info[i].max_avail = avail_space;
2027
2028                 i++;
2029         }
2030         rcu_read_unlock();
2031
2032         nr_devices = i;
2033
2034         btrfs_descending_sort_devices(devices_info, nr_devices);
2035
2036         i = nr_devices - 1;
2037         avail_space = 0;
2038         while (nr_devices >= min_stripes) {
2039                 if (num_stripes > nr_devices)
2040                         num_stripes = nr_devices;
2041
2042                 if (devices_info[i].max_avail >= min_stripe_size) {
2043                         int j;
2044                         u64 alloc_size;
2045
2046                         avail_space += devices_info[i].max_avail * num_stripes;
2047                         alloc_size = devices_info[i].max_avail;
2048                         for (j = i + 1 - num_stripes; j <= i; j++)
2049                                 devices_info[j].max_avail -= alloc_size;
2050                 }
2051                 i--;
2052                 nr_devices--;
2053         }
2054
2055         kfree(devices_info);
2056         *free_bytes = avail_space;
2057         return 0;
2058 }
2059
2060 /*
2061  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
2062  *
2063  * If there's a redundant raid level at DATA block groups, use the respective
2064  * multiplier to scale the sizes.
2065  *
2066  * Unused device space usage is based on simulating the chunk allocator
2067  * algorithm that respects the device sizes and order of allocations.  This is
2068  * a close approximation of the actual use but there are other factors that may
2069  * change the result (like a new metadata chunk).
2070  *
2071  * If metadata is exhausted, f_bavail will be 0.
2072  */
2073 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
2074 {
2075         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
2076         struct btrfs_super_block *disk_super = fs_info->super_copy;
2077         struct list_head *head = &fs_info->space_info;
2078         struct btrfs_space_info *found;
2079         u64 total_used = 0;
2080         u64 total_free_data = 0;
2081         u64 total_free_meta = 0;
2082         int bits = dentry->d_sb->s_blocksize_bits;
2083         __be32 *fsid = (__be32 *)fs_info->fsid;
2084         unsigned factor = 1;
2085         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
2086         int ret;
2087         u64 thresh = 0;
2088         int mixed = 0;
2089
2090         rcu_read_lock();
2091         list_for_each_entry_rcu(found, head, list) {
2092                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
2093                         int i;
2094
2095                         total_free_data += found->disk_total - found->disk_used;
2096                         total_free_data -=
2097                                 btrfs_account_ro_block_groups_free_space(found);
2098
2099                         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
2100                                 if (!list_empty(&found->block_groups[i])) {
2101                                         switch (i) {
2102                                         case BTRFS_RAID_DUP:
2103                                         case BTRFS_RAID_RAID1:
2104                                         case BTRFS_RAID_RAID10:
2105                                                 factor = 2;
2106                                         }
2107                                 }
2108                         }
2109                 }
2110
2111                 /*
2112                  * Metadata in mixed block goup profiles are accounted in data
2113                  */
2114                 if (!mixed && found->flags & BTRFS_BLOCK_GROUP_METADATA) {
2115                         if (found->flags & BTRFS_BLOCK_GROUP_DATA)
2116                                 mixed = 1;
2117                         else
2118                                 total_free_meta += found->disk_total -
2119                                         found->disk_used;
2120                 }
2121
2122                 total_used += found->disk_used;
2123         }
2124
2125         rcu_read_unlock();
2126
2127         buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
2128         buf->f_blocks >>= bits;
2129         buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
2130
2131         /* Account global block reserve as used, it's in logical size already */
2132         spin_lock(&block_rsv->lock);
2133         /* Mixed block groups accounting is not byte-accurate, avoid overflow */
2134         if (buf->f_bfree >= block_rsv->size >> bits)
2135                 buf->f_bfree -= block_rsv->size >> bits;
2136         else
2137                 buf->f_bfree = 0;
2138         spin_unlock(&block_rsv->lock);
2139
2140         buf->f_bavail = div_u64(total_free_data, factor);
2141         ret = btrfs_calc_avail_data_space(fs_info, &total_free_data);
2142         if (ret)
2143                 return ret;
2144         buf->f_bavail += div_u64(total_free_data, factor);
2145         buf->f_bavail = buf->f_bavail >> bits;
2146
2147         /*
2148          * We calculate the remaining metadata space minus global reserve. If
2149          * this is (supposedly) smaller than zero, there's no space. But this
2150          * does not hold in practice, the exhausted state happens where's still
2151          * some positive delta. So we apply some guesswork and compare the
2152          * delta to a 4M threshold.  (Practically observed delta was ~2M.)
2153          *
2154          * We probably cannot calculate the exact threshold value because this
2155          * depends on the internal reservations requested by various
2156          * operations, so some operations that consume a few metadata will
2157          * succeed even if the Avail is zero. But this is better than the other
2158          * way around.
2159          */
2160         thresh = SZ_4M;
2161
2162         if (!mixed && total_free_meta - thresh < block_rsv->size)
2163                 buf->f_bavail = 0;
2164
2165         buf->f_type = BTRFS_SUPER_MAGIC;
2166         buf->f_bsize = dentry->d_sb->s_blocksize;
2167         buf->f_namelen = BTRFS_NAME_LEN;
2168
2169         /* We treat it as constant endianness (it doesn't matter _which_)
2170            because we want the fsid to come out the same whether mounted
2171            on a big-endian or little-endian host */
2172         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
2173         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
2174         /* Mask in the root object ID too, to disambiguate subvols */
2175         buf->f_fsid.val[0] ^= BTRFS_I(d_inode(dentry))->root->objectid >> 32;
2176         buf->f_fsid.val[1] ^= BTRFS_I(d_inode(dentry))->root->objectid;
2177
2178         return 0;
2179 }
2180
2181 static void btrfs_kill_super(struct super_block *sb)
2182 {
2183         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2184         kill_anon_super(sb);
2185         free_fs_info(fs_info);
2186 }
2187
2188 static struct file_system_type btrfs_fs_type = {
2189         .owner          = THIS_MODULE,
2190         .name           = "btrfs",
2191         .mount          = btrfs_mount,
2192         .kill_sb        = btrfs_kill_super,
2193         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2194 };
2195
2196 static struct file_system_type btrfs_root_fs_type = {
2197         .owner          = THIS_MODULE,
2198         .name           = "btrfs",
2199         .mount          = btrfs_mount_root,
2200         .kill_sb        = btrfs_kill_super,
2201         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2202 };
2203
2204 MODULE_ALIAS_FS("btrfs");
2205
2206 static int btrfs_control_open(struct inode *inode, struct file *file)
2207 {
2208         /*
2209          * The control file's private_data is used to hold the
2210          * transaction when it is started and is used to keep
2211          * track of whether a transaction is already in progress.
2212          */
2213         file->private_data = NULL;
2214         return 0;
2215 }
2216
2217 /*
2218  * used by btrfsctl to scan devices when no FS is mounted
2219  */
2220 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
2221                                 unsigned long arg)
2222 {
2223         struct btrfs_ioctl_vol_args *vol;
2224         struct btrfs_fs_devices *fs_devices;
2225         int ret = -ENOTTY;
2226
2227         if (!capable(CAP_SYS_ADMIN))
2228                 return -EPERM;
2229
2230         vol = memdup_user((void __user *)arg, sizeof(*vol));
2231         if (IS_ERR(vol))
2232                 return PTR_ERR(vol);
2233
2234         switch (cmd) {
2235         case BTRFS_IOC_SCAN_DEV:
2236                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2237                                             &btrfs_root_fs_type, &fs_devices);
2238                 break;
2239         case BTRFS_IOC_DEVICES_READY:
2240                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2241                                             &btrfs_root_fs_type, &fs_devices);
2242                 if (ret)
2243                         break;
2244                 ret = !(fs_devices->num_devices == fs_devices->total_devices);
2245                 break;
2246         case BTRFS_IOC_GET_SUPPORTED_FEATURES:
2247                 ret = btrfs_ioctl_get_supported_features((void __user*)arg);
2248                 break;
2249         }
2250
2251         kfree(vol);
2252         return ret;
2253 }
2254
2255 static int btrfs_freeze(struct super_block *sb)
2256 {
2257         struct btrfs_trans_handle *trans;
2258         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2259         struct btrfs_root *root = fs_info->tree_root;
2260
2261         set_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2262         /*
2263          * We don't need a barrier here, we'll wait for any transaction that
2264          * could be in progress on other threads (and do delayed iputs that
2265          * we want to avoid on a frozen filesystem), or do the commit
2266          * ourselves.
2267          */
2268         trans = btrfs_attach_transaction_barrier(root);
2269         if (IS_ERR(trans)) {
2270                 /* no transaction, don't bother */
2271                 if (PTR_ERR(trans) == -ENOENT)
2272                         return 0;
2273                 return PTR_ERR(trans);
2274         }
2275         return btrfs_commit_transaction(trans);
2276 }
2277
2278 static int btrfs_unfreeze(struct super_block *sb)
2279 {
2280         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2281
2282         clear_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2283         return 0;
2284 }
2285
2286 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
2287 {
2288         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
2289         struct btrfs_fs_devices *cur_devices;
2290         struct btrfs_device *dev, *first_dev = NULL;
2291         struct list_head *head;
2292         struct rcu_string *name;
2293
2294         /*
2295          * Lightweight locking of the devices. We should not need
2296          * device_list_mutex here as we only read the device data and the list
2297          * is protected by RCU.  Even if a device is deleted during the list
2298          * traversals, we'll get valid data, the freeing callback will wait at
2299          * least until until the rcu_read_unlock.
2300          */
2301         rcu_read_lock();
2302         cur_devices = fs_info->fs_devices;
2303         while (cur_devices) {
2304                 head = &cur_devices->devices;
2305                 list_for_each_entry_rcu(dev, head, dev_list) {
2306                         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state))
2307                                 continue;
2308                         if (!dev->name)
2309                                 continue;
2310                         if (!first_dev || dev->devid < first_dev->devid)
2311                                 first_dev = dev;
2312                 }
2313                 cur_devices = cur_devices->seed;
2314         }
2315
2316         if (first_dev) {
2317                 name = rcu_dereference(first_dev->name);
2318                 seq_escape(m, name->str, " \t\n\\");
2319         } else {
2320                 WARN_ON(1);
2321         }
2322         rcu_read_unlock();
2323         return 0;
2324 }
2325
2326 static const struct super_operations btrfs_super_ops = {
2327         .drop_inode     = btrfs_drop_inode,
2328         .evict_inode    = btrfs_evict_inode,
2329         .put_super      = btrfs_put_super,
2330         .sync_fs        = btrfs_sync_fs,
2331         .show_options   = btrfs_show_options,
2332         .show_devname   = btrfs_show_devname,
2333         .write_inode    = btrfs_write_inode,
2334         .alloc_inode    = btrfs_alloc_inode,
2335         .destroy_inode  = btrfs_destroy_inode,
2336         .statfs         = btrfs_statfs,
2337         .remount_fs     = btrfs_remount,
2338         .freeze_fs      = btrfs_freeze,
2339         .unfreeze_fs    = btrfs_unfreeze,
2340 };
2341
2342 static const struct file_operations btrfs_ctl_fops = {
2343         .open = btrfs_control_open,
2344         .unlocked_ioctl  = btrfs_control_ioctl,
2345         .compat_ioctl = btrfs_control_ioctl,
2346         .owner   = THIS_MODULE,
2347         .llseek = noop_llseek,
2348 };
2349
2350 static struct miscdevice btrfs_misc = {
2351         .minor          = BTRFS_MINOR,
2352         .name           = "btrfs-control",
2353         .fops           = &btrfs_ctl_fops
2354 };
2355
2356 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2357 MODULE_ALIAS("devname:btrfs-control");
2358
2359 static int __init btrfs_interface_init(void)
2360 {
2361         return misc_register(&btrfs_misc);
2362 }
2363
2364 static __cold void btrfs_interface_exit(void)
2365 {
2366         misc_deregister(&btrfs_misc);
2367 }
2368
2369 static void __init btrfs_print_mod_info(void)
2370 {
2371         pr_info("Btrfs loaded, crc32c=%s"
2372 #ifdef CONFIG_BTRFS_DEBUG
2373                         ", debug=on"
2374 #endif
2375 #ifdef CONFIG_BTRFS_ASSERT
2376                         ", assert=on"
2377 #endif
2378 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2379                         ", integrity-checker=on"
2380 #endif
2381 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
2382                         ", ref-verify=on"
2383 #endif
2384                         "\n",
2385                         crc32c_impl());
2386 }
2387
2388 static int __init init_btrfs_fs(void)
2389 {
2390         int err;
2391
2392         btrfs_props_init();
2393
2394         err = btrfs_init_sysfs();
2395         if (err)
2396                 return err;
2397
2398         btrfs_init_compress();
2399
2400         err = btrfs_init_cachep();
2401         if (err)
2402                 goto free_compress;
2403
2404         err = extent_io_init();
2405         if (err)
2406                 goto free_cachep;
2407
2408         err = extent_map_init();
2409         if (err)
2410                 goto free_extent_io;
2411
2412         err = ordered_data_init();
2413         if (err)
2414                 goto free_extent_map;
2415
2416         err = btrfs_delayed_inode_init();
2417         if (err)
2418                 goto free_ordered_data;
2419
2420         err = btrfs_auto_defrag_init();
2421         if (err)
2422                 goto free_delayed_inode;
2423
2424         err = btrfs_delayed_ref_init();
2425         if (err)
2426                 goto free_auto_defrag;
2427
2428         err = btrfs_prelim_ref_init();
2429         if (err)
2430                 goto free_delayed_ref;
2431
2432         err = btrfs_end_io_wq_init();
2433         if (err)
2434                 goto free_prelim_ref;
2435
2436         err = btrfs_interface_init();
2437         if (err)
2438                 goto free_end_io_wq;
2439
2440         btrfs_init_lockdep();
2441
2442         btrfs_print_mod_info();
2443
2444         err = btrfs_run_sanity_tests();
2445         if (err)
2446                 goto unregister_ioctl;
2447
2448         err = register_filesystem(&btrfs_fs_type);
2449         if (err)
2450                 goto unregister_ioctl;
2451
2452         return 0;
2453
2454 unregister_ioctl:
2455         btrfs_interface_exit();
2456 free_end_io_wq:
2457         btrfs_end_io_wq_exit();
2458 free_prelim_ref:
2459         btrfs_prelim_ref_exit();
2460 free_delayed_ref:
2461         btrfs_delayed_ref_exit();
2462 free_auto_defrag:
2463         btrfs_auto_defrag_exit();
2464 free_delayed_inode:
2465         btrfs_delayed_inode_exit();
2466 free_ordered_data:
2467         ordered_data_exit();
2468 free_extent_map:
2469         extent_map_exit();
2470 free_extent_io:
2471         extent_io_exit();
2472 free_cachep:
2473         btrfs_destroy_cachep();
2474 free_compress:
2475         btrfs_exit_compress();
2476         btrfs_exit_sysfs();
2477
2478         return err;
2479 }
2480
2481 static void __exit exit_btrfs_fs(void)
2482 {
2483         btrfs_destroy_cachep();
2484         btrfs_delayed_ref_exit();
2485         btrfs_auto_defrag_exit();
2486         btrfs_delayed_inode_exit();
2487         btrfs_prelim_ref_exit();
2488         ordered_data_exit();
2489         extent_map_exit();
2490         extent_io_exit();
2491         btrfs_interface_exit();
2492         btrfs_end_io_wq_exit();
2493         unregister_filesystem(&btrfs_fs_type);
2494         btrfs_exit_sysfs();
2495         btrfs_cleanup_fs_uuids();
2496         btrfs_exit_compress();
2497 }
2498
2499 late_initcall(init_btrfs_fs);
2500 module_exit(exit_btrfs_fs)
2501
2502 MODULE_LICENSE("GPL");