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/fs.h>
   9 #include <linux/pagemap.h>
  10 #include <linux/highmem.h>
  11 #include <linux/time.h>
  12 #include <linux/init.h>
  13 #include <linux/seq_file.h>
  14 #include <linux/string.h>
  15 #include <linux/backing-dev.h>
  16 #include <linux/mount.h>
  17 #include <linux/writeback.h>
  18 #include <linux/statfs.h>
  19 #include <linux/compat.h>
  20 #include <linux/parser.h>
  21 #include <linux/ctype.h>
  22 #include <linux/namei.h>
  23 #include <linux/miscdevice.h>
  24 #include <linux/magic.h>
  25 #include <linux/slab.h>
  26 #include <linux/cleancache.h>
  27 #include <linux/ratelimit.h>
  28 #include <linux/crc32c.h>
  29 #include <linux/btrfs.h>
  30 #include "delayed-inode.h"
  31 #include "ctree.h"
  32 #include "disk-io.h"
  33 #include "transaction.h"
  34 #include "btrfs_inode.h"
  35 #include "print-tree.h"
  36 #include "props.h"
  37 #include "xattr.h"
  38 #include "volumes.h"
  39 #include "export.h"
  40 #include "compression.h"
  41 #include "rcu-string.h"
  42 #include "dev-replace.h"
  43 #include "free-space-cache.h"
  44 #include "backref.h"
  45 #include "tests/btrfs-tests.h"
  46
  47 #include "qgroup.h"
  48 #define CREATE_TRACE_POINTS
  49 #include <trace/events/btrfs.h>
  50
  51 static const struct super_operations btrfs_super_ops;
  52
  53 /*
  54  * Types for mounting the default subvolume and a subvolume explicitly
  55  * requested by subvol=/path. That way the callchain is straightforward and we
  56  * don't have to play tricks with the mount options and recursive calls to
  57  * btrfs_mount.
  58  *
  59  * The new btrfs_root_fs_type also servers as a tag for the bdev_holder.
  60  */
  61 static struct file_system_type btrfs_fs_type;
  62 static struct file_system_type btrfs_root_fs_type;
  63
  64 static int btrfs_remount(struct super_block *sb, int *flags, char *data);
  65
  66 const char *btrfs_decode_error(int errno)
  67 {
  68         char *errstr = "unknown";
  69
  70         switch (errno) {
  71         case -EIO:
  72                 errstr = "IO failure";
  73                 break;
  74         case -ENOMEM:
  75                 errstr = "Out of memory";
  76                 break;
  77         case -EROFS:
  78                 errstr = "Readonly filesystem";
  79                 break;
  80         case -EEXIST:
  81                 errstr = "Object already exists";
  82                 break;
  83         case -ENOSPC:
  84                 errstr = "No space left";
  85                 break;
  86         case -ENOENT:
  87                 errstr = "No such entry";
  88                 break;
  89         }
  90
  91         return errstr;
  92 }
  93
  94 /*
  95  * __btrfs_handle_fs_error decodes expected errors from the caller and
  96  * invokes the approciate error response.
  97  */
  98 __cold
  99 void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function,
 100                        unsigned int line, int errno, const char *fmt, ...)
 101 {
 102         struct super_block *sb = fs_info->sb;
 103 #ifdef CONFIG_PRINTK
 104         const char *errstr;
 105 #endif
 106
 107         /*
 108          * Special case: if the error is EROFS, and we're already
 109          * under SB_RDONLY, then it is safe here.
 110          */
 111         if (errno == -EROFS && sb_rdonly(sb))
 112                 return;
 113
 114 #ifdef CONFIG_PRINTK
 115         errstr = btrfs_decode_error(errno);
 116         if (fmt) {
 117                 struct va_format vaf;
 118                 va_list args;
 119
 120                 va_start(args, fmt);
 121                 vaf.fmt = fmt;
 122                 vaf.va = &args;
 123
 124                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s (%pV)\n",
 125                         sb->s_id, function, line, errno, errstr, &vaf);
 126                 va_end(args);
 127         } else {
 128                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s\n",
 129                         sb->s_id, function, line, errno, errstr);
 130         }
 131 #endif
 132
 133         /*
 134          * Today we only save the error info to memory.  Long term we'll
 135          * also send it down to the disk
 136          */
 137         set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
 138
 139         /* Don't go through full error handling during mount */
 140         if (!(sb->s_flags & SB_BORN))
 141                 return;
 142
 143         if (sb_rdonly(sb))
 144                 return;
 145
 146         /* btrfs handle error by forcing the filesystem readonly */
 147         sb->s_flags |= SB_RDONLY;
 148         btrfs_info(fs_info, "forced readonly");
 149         /*
 150          * Note that a running device replace operation is not canceled here
 151          * although there is no way to update the progress. It would add the
 152          * risk of a deadlock, therefore the canceling is omitted. The only
 153          * penalty is that some I/O remains active until the procedure
 154          * completes. The next time when the filesystem is mounted writeable
 155          * again, the device replace operation continues.
 156          */
 157 }
 158
 159 #ifdef CONFIG_PRINTK
 160 static const char * const logtypes[] = {
 161         "emergency",
 162         "alert",
 163         "critical",
 164         "error",
 165         "warning",
 166         "notice",
 167         "info",
 168         "debug",
 169 };
 170
 171
 172 /*
 173  * Use one ratelimit state per log level so that a flood of less important
 174  * messages doesn't cause more important ones to be dropped.
 175  */
 176 static struct ratelimit_state printk_limits[] = {
 177         RATELIMIT_STATE_INIT(printk_limits[0], DEFAULT_RATELIMIT_INTERVAL, 100),
 178         RATELIMIT_STATE_INIT(printk_limits[1], DEFAULT_RATELIMIT_INTERVAL, 100),
 179         RATELIMIT_STATE_INIT(printk_limits[2], DEFAULT_RATELIMIT_INTERVAL, 100),
 180         RATELIMIT_STATE_INIT(printk_limits[3], DEFAULT_RATELIMIT_INTERVAL, 100),
 181         RATELIMIT_STATE_INIT(printk_limits[4], DEFAULT_RATELIMIT_INTERVAL, 100),
 182         RATELIMIT_STATE_INIT(printk_limits[5], DEFAULT_RATELIMIT_INTERVAL, 100),
 183         RATELIMIT_STATE_INIT(printk_limits[6], DEFAULT_RATELIMIT_INTERVAL, 100),
 184         RATELIMIT_STATE_INIT(printk_limits[7], DEFAULT_RATELIMIT_INTERVAL, 100),
 185 };
 186
 187 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 188 {
 189         char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1] = "\0";
 190         struct va_format vaf;
 191         va_list args;
 192         int kern_level;
 193         const char *type = logtypes[4];
 194         struct ratelimit_state *ratelimit = &printk_limits[4];
 195
 196         va_start(args, fmt);
 197
 198         while ((kern_level = printk_get_level(fmt)) != 0) {
 199                 size_t size = printk_skip_level(fmt) - fmt;
 200
 201                 if (kern_level >= '0' && kern_level <= '7') {
 202                         memcpy(lvl, fmt,  size);
 203                         lvl[size] = '\0';
 204                         type = logtypes[kern_level - '0'];
 205                         ratelimit = &printk_limits[kern_level - '0'];
 206                 }
 207                 fmt += size;
 208         }
 209
 210         vaf.fmt = fmt;
 211         vaf.va = &args;
 212
 213         if (__ratelimit(ratelimit))
 214                 printk("%sBTRFS %s (device %s): %pV\n", lvl, type,
 215                         fs_info ? fs_info->sb->s_id : "<unknown>", &vaf);
 216
 217         va_end(args);
 218 }
 219 #endif
 220
 221 /*
 222  * We only mark the transaction aborted and then set the file system read-only.
 223  * This will prevent new transactions from starting or trying to join this
 224  * one.
 225  *
 226  * This means that error recovery at the call site is limited to freeing
 227  * any local memory allocations and passing the error code up without
 228  * further cleanup. The transaction should complete as it normally would
 229  * in the call path but will return -EIO.
 230  *
 231  * We'll complete the cleanup in btrfs_end_transaction and
 232  * btrfs_commit_transaction.
 233  */
 234 __cold
 235 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 236                                const char *function,
 237                                unsigned int line, int errno)
 238 {
 239         struct btrfs_fs_info *fs_info = trans->fs_info;
 240
 241         trans->aborted = errno;
 242         /* Nothing used. The other threads that have joined this
 243          * transaction may be able to continue. */
 244         if (!trans->dirty && list_empty(&trans->new_bgs)) {
 245                 const char *errstr;
 246
 247                 errstr = btrfs_decode_error(errno);
 248                 btrfs_warn(fs_info,
 249                            "%s:%d: Aborting unused transaction(%s).",
 250                            function, line, errstr);
 251                 return;
 252         }
 253         WRITE_ONCE(trans->transaction->aborted, errno);
 254         /* Wake up anybody who may be waiting on this transaction */
 255         wake_up(&fs_info->transaction_wait);
 256         wake_up(&fs_info->transaction_blocked_wait);
 257         __btrfs_handle_fs_error(fs_info, function, line, errno, NULL);
 258 }
 259 /*
 260  * __btrfs_panic decodes unexpected, fatal errors from the caller,
 261  * issues an alert, and either panics or BUGs, depending on mount options.
 262  */
 263 __cold
 264 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 265                    unsigned int line, int errno, const char *fmt, ...)
 266 {
 267         char *s_id = "<unknown>";
 268         const char *errstr;
 269         struct va_format vaf = { .fmt = fmt };
 270         va_list args;
 271
 272         if (fs_info)
 273                 s_id = fs_info->sb->s_id;
 274
 275         va_start(args, fmt);
 276         vaf.va = &args;
 277
 278         errstr = btrfs_decode_error(errno);
 279         if (fs_info && (btrfs_test_opt(fs_info, PANIC_ON_FATAL_ERROR)))
 280                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
 281                         s_id, function, line, &vaf, errno, errstr);
 282
 283         btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
 284                    function, line, &vaf, errno, errstr);
 285         va_end(args);
 286         /* Caller calls BUG() */
 287 }
 288
 289 static void btrfs_put_super(struct super_block *sb)
 290 {
 291         close_ctree(btrfs_sb(sb));
 292 }
 293
 294 enum {
 295         Opt_acl, Opt_noacl,
 296         Opt_clear_cache,
 297         Opt_commit_interval,
 298         Opt_compress,
 299         Opt_compress_force,
 300         Opt_compress_force_type,
 301         Opt_compress_type,
 302         Opt_degraded,
 303         Opt_device,
 304         Opt_fatal_errors,
 305         Opt_flushoncommit, Opt_noflushoncommit,
 306         Opt_inode_cache, Opt_noinode_cache,
 307         Opt_max_inline,
 308         Opt_barrier, Opt_nobarrier,
 309         Opt_datacow, Opt_nodatacow,
 310         Opt_datasum, Opt_nodatasum,
 311         Opt_defrag, Opt_nodefrag,
 312         Opt_discard, Opt_nodiscard,
 313         Opt_nologreplay,
 314         Opt_norecovery,
 315         Opt_ratio,
 316         Opt_rescan_uuid_tree,
 317         Opt_skip_balance,
 318         Opt_space_cache, Opt_no_space_cache,
 319         Opt_space_cache_version,
 320         Opt_ssd, Opt_nossd,
 321         Opt_ssd_spread, Opt_nossd_spread,
 322         Opt_subvol,
 323         Opt_subvol_empty,
 324         Opt_subvolid,
 325         Opt_thread_pool,
 326         Opt_treelog, Opt_notreelog,
 327         Opt_usebackuproot,
 328         Opt_user_subvol_rm_allowed,
 329
 330         /* Deprecated options */
 331         Opt_alloc_start,
 332         Opt_recovery,
 333         Opt_subvolrootid,
 334
 335         /* Debugging options */
 336         Opt_check_integrity,
 337         Opt_check_integrity_including_extent_data,
 338         Opt_check_integrity_print_mask,
 339         Opt_enospc_debug, Opt_noenospc_debug,
 340 #ifdef CONFIG_BTRFS_DEBUG
 341         Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 342 #endif
 343 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 344         Opt_ref_verify,
 345 #endif
 346         Opt_err,
 347 };
 348
 349 static const match_table_t tokens = {
 350         {Opt_acl, "acl"},
 351         {Opt_noacl, "noacl"},
 352         {Opt_clear_cache, "clear_cache"},
 353         {Opt_commit_interval, "commit=%u"},
 354         {Opt_compress, "compress"},
 355         {Opt_compress_type, "compress=%s"},
 356         {Opt_compress_force, "compress-force"},
 357         {Opt_compress_force_type, "compress-force=%s"},
 358         {Opt_degraded, "degraded"},
 359         {Opt_device, "device=%s"},
 360         {Opt_fatal_errors, "fatal_errors=%s"},
 361         {Opt_flushoncommit, "flushoncommit"},
 362         {Opt_noflushoncommit, "noflushoncommit"},
 363         {Opt_inode_cache, "inode_cache"},
 364         {Opt_noinode_cache, "noinode_cache"},
 365         {Opt_max_inline, "max_inline=%s"},
 366         {Opt_barrier, "barrier"},
 367         {Opt_nobarrier, "nobarrier"},
 368         {Opt_datacow, "datacow"},
 369         {Opt_nodatacow, "nodatacow"},
 370         {Opt_datasum, "datasum"},
 371         {Opt_nodatasum, "nodatasum"},
 372         {Opt_defrag, "autodefrag"},
 373         {Opt_nodefrag, "noautodefrag"},
 374         {Opt_discard, "discard"},
 375         {Opt_nodiscard, "nodiscard"},
 376         {Opt_nologreplay, "nologreplay"},
 377         {Opt_norecovery, "norecovery"},
 378         {Opt_ratio, "metadata_ratio=%u"},
 379         {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
 380         {Opt_skip_balance, "skip_balance"},
 381         {Opt_space_cache, "space_cache"},
 382         {Opt_no_space_cache, "nospace_cache"},
 383         {Opt_space_cache_version, "space_cache=%s"},
 384         {Opt_ssd, "ssd"},
 385         {Opt_nossd, "nossd"},
 386         {Opt_ssd_spread, "ssd_spread"},
 387         {Opt_nossd_spread, "nossd_spread"},
 388         {Opt_subvol, "subvol=%s"},
 389         {Opt_subvol_empty, "subvol="},
 390         {Opt_subvolid, "subvolid=%s"},
 391         {Opt_thread_pool, "thread_pool=%u"},
 392         {Opt_treelog, "treelog"},
 393         {Opt_notreelog, "notreelog"},
 394         {Opt_usebackuproot, "usebackuproot"},
 395         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 396
 397         /* Deprecated options */
 398         {Opt_alloc_start, "alloc_start=%s"},
 399         {Opt_recovery, "recovery"},
 400         {Opt_subvolrootid, "subvolrootid=%d"},
 401
 402         /* Debugging options */
 403         {Opt_check_integrity, "check_int"},
 404         {Opt_check_integrity_including_extent_data, "check_int_data"},
 405         {Opt_check_integrity_print_mask, "check_int_print_mask=%u"},
 406         {Opt_enospc_debug, "enospc_debug"},
 407         {Opt_noenospc_debug, "noenospc_debug"},
 408 #ifdef CONFIG_BTRFS_DEBUG
 409         {Opt_fragment_data, "fragment=data"},
 410         {Opt_fragment_metadata, "fragment=metadata"},
 411         {Opt_fragment_all, "fragment=all"},
 412 #endif
 413 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 414         {Opt_ref_verify, "ref_verify"},
 415 #endif
 416         {Opt_err, NULL},
 417 };
 418
 419 /*
 420  * Regular mount options parser.  Everything that is needed only when
 421  * reading in a new superblock is parsed here.
 422  * XXX JDM: This needs to be cleaned up for remount.
 423  */
 424 int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 425                         unsigned long new_flags)
 426 {
 427         substring_t args[MAX_OPT_ARGS];
 428         char *p, *num;
 429         u64 cache_gen;
 430         int intarg;
 431         int ret = 0;
 432         char *compress_type;
 433         bool compress_force = false;
 434         enum btrfs_compression_type saved_compress_type;
 435         bool saved_compress_force;
 436         int no_compress = 0;
 437
 438         cache_gen = btrfs_super_cache_generation(info->super_copy);
 439         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
 440                 btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
 441         else if (cache_gen)
 442                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 443
 444         /*
 445          * Even the options are empty, we still need to do extra check
 446          * against new flags
 447          */
 448         if (!options)
 449                 goto check;
 450
 451         while ((p = strsep(&options, ",")) != NULL) {
 452                 int token;
 453                 if (!*p)
 454                         continue;
 455
 456                 token = match_token(p, tokens, args);
 457                 switch (token) {
 458                 case Opt_degraded:
 459                         btrfs_info(info, "allowing degraded mounts");
 460                         btrfs_set_opt(info->mount_opt, DEGRADED);
 461                         break;
 462                 case Opt_subvol:
 463                 case Opt_subvol_empty:
 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                         /* fall through */
 761                 case Opt_usebackuproot:
 762                         btrfs_info(info,
 763                                    "trying to use backup root at mount time");
 764                         btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
 765                         break;
 766                 case Opt_skip_balance:
 767                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 768                         break;
 769 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 770                 case Opt_check_integrity_including_extent_data:
 771                         btrfs_info(info,
 772                                    "enabling check integrity including extent data");
 773                         btrfs_set_opt(info->mount_opt,
 774                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 775                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 776                         break;
 777                 case Opt_check_integrity:
 778                         btrfs_info(info, "enabling check integrity");
 779                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 780                         break;
 781                 case Opt_check_integrity_print_mask:
 782                         ret = match_int(&args[0], &intarg);
 783                         if (ret)
 784                                 goto out;
 785                         info->check_integrity_print_mask = intarg;
 786                         btrfs_info(info, "check_integrity_print_mask 0x%x",
 787                                    info->check_integrity_print_mask);
 788                         break;
 789 #else
 790                 case Opt_check_integrity_including_extent_data:
 791                 case Opt_check_integrity:
 792                 case Opt_check_integrity_print_mask:
 793                         btrfs_err(info,
 794                                   "support for check_integrity* not compiled in!");
 795                         ret = -EINVAL;
 796                         goto out;
 797 #endif
 798                 case Opt_fatal_errors:
 799                         if (strcmp(args[0].from, "panic") == 0)
 800                                 btrfs_set_opt(info->mount_opt,
 801                                               PANIC_ON_FATAL_ERROR);
 802                         else if (strcmp(args[0].from, "bug") == 0)
 803                                 btrfs_clear_opt(info->mount_opt,
 804                                               PANIC_ON_FATAL_ERROR);
 805                         else {
 806                                 ret = -EINVAL;
 807                                 goto out;
 808                         }
 809                         break;
 810                 case Opt_commit_interval:
 811                         intarg = 0;
 812                         ret = match_int(&args[0], &intarg);
 813                         if (ret)
 814                                 goto out;
 815                         if (intarg == 0) {
 816                                 btrfs_info(info,
 817                                            "using default commit interval %us",
 818                                            BTRFS_DEFAULT_COMMIT_INTERVAL);
 819                                 intarg = BTRFS_DEFAULT_COMMIT_INTERVAL;
 820                         } else if (intarg > 300) {
 821                                 btrfs_warn(info, "excessive commit interval %d",
 822                                            intarg);
 823                         }
 824                         info->commit_interval = intarg;
 825                         break;
 826 #ifdef CONFIG_BTRFS_DEBUG
 827                 case Opt_fragment_all:
 828                         btrfs_info(info, "fragmenting all space");
 829                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 830                         btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
 831                         break;
 832                 case Opt_fragment_metadata:
 833                         btrfs_info(info, "fragmenting metadata");
 834                         btrfs_set_opt(info->mount_opt,
 835                                       FRAGMENT_METADATA);
 836                         break;
 837                 case Opt_fragment_data:
 838                         btrfs_info(info, "fragmenting data");
 839                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 840                         break;
 841 #endif
 842 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 843                 case Opt_ref_verify:
 844                         btrfs_info(info, "doing ref verification");
 845                         btrfs_set_opt(info->mount_opt, REF_VERIFY);
 846                         break;
 847 #endif
 848                 case Opt_err:
 849                         btrfs_info(info, "unrecognized mount option '%s'", p);
 850                         ret = -EINVAL;
 851                         goto out;
 852                 default:
 853                         break;
 854                 }
 855         }
 856 check:
 857         /*
 858          * Extra check for current option against current flag
 859          */
 860         if (btrfs_test_opt(info, NOLOGREPLAY) && !(new_flags & SB_RDONLY)) {
 861                 btrfs_err(info,
 862                           "nologreplay must be used with ro mount option");
 863                 ret = -EINVAL;
 864         }
 865 out:
 866         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) &&
 867             !btrfs_test_opt(info, FREE_SPACE_TREE) &&
 868             !btrfs_test_opt(info, CLEAR_CACHE)) {
 869                 btrfs_err(info, "cannot disable free space tree");
 870                 ret = -EINVAL;
 871
 872         }
 873         if (!ret && btrfs_test_opt(info, SPACE_CACHE))
 874                 btrfs_info(info, "disk space caching is enabled");
 875         if (!ret && btrfs_test_opt(info, FREE_SPACE_TREE))
 876                 btrfs_info(info, "using free space tree");
 877         return ret;
 878 }
 879
 880 /*
 881  * Parse mount options that are required early in the mount process.
 882  *
 883  * All other options will be parsed on much later in the mount process and
 884  * only when we need to allocate a new super block.
 885  */
 886 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 887                 void *holder, struct btrfs_fs_devices **fs_devices)
 888 {
 889         substring_t args[MAX_OPT_ARGS];
 890         char *device_name, *opts, *orig, *p;
 891         int error = 0;
 892
 893         if (!options)
 894                 return 0;
 895
 896         /*
 897          * strsep changes the string, duplicate it because btrfs_parse_options
 898          * gets called later
 899          */
 900         opts = kstrdup(options, GFP_KERNEL);
 901         if (!opts)
 902                 return -ENOMEM;
 903         orig = opts;
 904
 905         while ((p = strsep(&opts, ",")) != NULL) {
 906                 int token;
 907
 908                 if (!*p)
 909                         continue;
 910
 911                 token = match_token(p, tokens, args);
 912                 if (token == Opt_device) {
 913                         device_name = match_strdup(&args[0]);
 914                         if (!device_name) {
 915                                 error = -ENOMEM;
 916                                 goto out;
 917                         }
 918                         mutex_lock(&uuid_mutex);
 919                         error = btrfs_scan_one_device(device_name,
 920                                         flags, holder, fs_devices);
 921                         mutex_unlock(&uuid_mutex);
 922                         kfree(device_name);
 923                         if (error)
 924                                 goto out;
 925                 }
 926         }
 927
 928 out:
 929         kfree(orig);
 930         return error;
 931 }
 932
 933 /*
 934  * Parse mount options that are related to subvolume id
 935  *
 936  * The value is later passed to mount_subvol()
 937  */
 938 static int btrfs_parse_subvol_options(const char *options, char **subvol_name,
 939                 u64 *subvol_objectid)
 940 {
 941         substring_t args[MAX_OPT_ARGS];
 942         char *opts, *orig, *p;
 943         int error = 0;
 944         u64 subvolid;
 945
 946         if (!options)
 947                 return 0;
 948
 949         /*
 950          * strsep changes the string, duplicate it because
 951          * btrfs_parse_early_options gets called later
 952          */
 953         opts = kstrdup(options, GFP_KERNEL);
 954         if (!opts)
 955                 return -ENOMEM;
 956         orig = opts;
 957
 958         while ((p = strsep(&opts, ",")) != NULL) {
 959                 int token;
 960                 if (!*p)
 961                         continue;
 962
 963                 token = match_token(p, tokens, args);
 964                 switch (token) {
 965                 case Opt_subvol:
 966                         kfree(*subvol_name);
 967                         *subvol_name = match_strdup(&args[0]);
 968                         if (!*subvol_name) {
 969                                 error = -ENOMEM;
 970                                 goto out;
 971                         }
 972                         break;
 973                 case Opt_subvolid:
 974                         error = match_u64(&args[0], &subvolid);
 975                         if (error)
 976                                 goto out;
 977
 978                         /* we want the original fs_tree */
 979                         if (subvolid == 0)
 980                                 subvolid = BTRFS_FS_TREE_OBJECTID;
 981
 982                         *subvol_objectid = subvolid;
 983                         break;
 984                 case Opt_subvolrootid:
 985                         pr_warn("BTRFS: 'subvolrootid' mount option is deprecated and has no effect\n");
 986                         break;
 987                 default:
 988                         break;
 989                 }
 990         }
 991
 992 out:
 993         kfree(orig);
 994         return error;
 995 }
 996
 997 static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 998                                            u64 subvol_objectid)
 999 {
1000         struct btrfs_root *root = fs_info->tree_root;
1001         struct btrfs_root *fs_root;
1002         struct btrfs_root_ref *root_ref;
1003         struct btrfs_inode_ref *inode_ref;
1004         struct btrfs_key key;
1005         struct btrfs_path *path = NULL;
1006         char *name = NULL, *ptr;
1007         u64 dirid;
1008         int len;
1009         int ret;
1010
1011         path = btrfs_alloc_path();
1012         if (!path) {
1013                 ret = -ENOMEM;
1014                 goto err;
1015         }
1016         path->leave_spinning = 1;
1017
1018         name = kmalloc(PATH_MAX, GFP_KERNEL);
1019         if (!name) {
1020                 ret = -ENOMEM;
1021                 goto err;
1022         }
1023         ptr = name + PATH_MAX - 1;
1024         ptr[0] = '\0';
1025
1026         /*
1027          * Walk up the subvolume trees in the tree of tree roots by root
1028          * backrefs until we hit the top-level subvolume.
1029          */
1030         while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
1031                 key.objectid = subvol_objectid;
1032                 key.type = BTRFS_ROOT_BACKREF_KEY;
1033                 key.offset = (u64)-1;
1034
1035                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1036                 if (ret < 0) {
1037                         goto err;
1038                 } else if (ret > 0) {
1039                         ret = btrfs_previous_item(root, path, subvol_objectid,
1040                                                   BTRFS_ROOT_BACKREF_KEY);
1041                         if (ret < 0) {
1042                                 goto err;
1043                         } else if (ret > 0) {
1044                                 ret = -ENOENT;
1045                                 goto err;
1046                         }
1047                 }
1048
1049                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1050                 subvol_objectid = key.offset;
1051
1052                 root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1053                                           struct btrfs_root_ref);
1054                 len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
1055                 ptr -= len + 1;
1056                 if (ptr < name) {
1057                         ret = -ENAMETOOLONG;
1058                         goto err;
1059                 }
1060                 read_extent_buffer(path->nodes[0], ptr + 1,
1061                                    (unsigned long)(root_ref + 1), len);
1062                 ptr[0] = '/';
1063                 dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
1064                 btrfs_release_path(path);
1065
1066                 key.objectid = subvol_objectid;
1067                 key.type = BTRFS_ROOT_ITEM_KEY;
1068                 key.offset = (u64)-1;
1069                 fs_root = btrfs_read_fs_root_no_name(fs_info, &key);
1070                 if (IS_ERR(fs_root)) {
1071                         ret = PTR_ERR(fs_root);
1072                         goto err;
1073                 }
1074
1075                 /*
1076                  * Walk up the filesystem tree by inode refs until we hit the
1077                  * root directory.
1078                  */
1079                 while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
1080                         key.objectid = dirid;
1081                         key.type = BTRFS_INODE_REF_KEY;
1082                         key.offset = (u64)-1;
1083
1084                         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1085                         if (ret < 0) {
1086                                 goto err;
1087                         } else if (ret > 0) {
1088                                 ret = btrfs_previous_item(fs_root, path, dirid,
1089                                                           BTRFS_INODE_REF_KEY);
1090                                 if (ret < 0) {
1091                                         goto err;
1092                                 } else if (ret > 0) {
1093                                         ret = -ENOENT;
1094                                         goto err;
1095                                 }
1096                         }
1097
1098                         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1099                         dirid = key.offset;
1100
1101                         inode_ref = btrfs_item_ptr(path->nodes[0],
1102                                                    path->slots[0],
1103                                                    struct btrfs_inode_ref);
1104                         len = btrfs_inode_ref_name_len(path->nodes[0],
1105                                                        inode_ref);
1106                         ptr -= len + 1;
1107                         if (ptr < name) {
1108                                 ret = -ENAMETOOLONG;
1109                                 goto err;
1110                         }
1111                         read_extent_buffer(path->nodes[0], ptr + 1,
1112                                            (unsigned long)(inode_ref + 1), len);
1113                         ptr[0] = '/';
1114                         btrfs_release_path(path);
1115                 }
1116         }
1117
1118         btrfs_free_path(path);
1119         if (ptr == name + PATH_MAX - 1) {
1120                 name[0] = '/';
1121                 name[1] = '\0';
1122         } else {
1123                 memmove(name, ptr, name + PATH_MAX - ptr);
1124         }
1125         return name;
1126
1127 err:
1128         btrfs_free_path(path);
1129         kfree(name);
1130         return ERR_PTR(ret);
1131 }
1132
1133 static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
1134 {
1135         struct btrfs_root *root = fs_info->tree_root;
1136         struct btrfs_dir_item *di;
1137         struct btrfs_path *path;
1138         struct btrfs_key location;
1139         u64 dir_id;
1140
1141         path = btrfs_alloc_path();
1142         if (!path)
1143                 return -ENOMEM;
1144         path->leave_spinning = 1;
1145
1146         /*
1147          * Find the "default" dir item which points to the root item that we
1148          * will mount by default if we haven't been given a specific subvolume
1149          * to mount.
1150          */
1151         dir_id = btrfs_super_root_dir(fs_info->super_copy);
1152         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
1153         if (IS_ERR(di)) {
1154                 btrfs_free_path(path);
1155                 return PTR_ERR(di);
1156         }
1157         if (!di) {
1158                 /*
1159                  * Ok the default dir item isn't there.  This is weird since
1160                  * it's always been there, but don't freak out, just try and
1161                  * mount the top-level subvolume.
1162                  */
1163                 btrfs_free_path(path);
1164                 *objectid = BTRFS_FS_TREE_OBJECTID;
1165                 return 0;
1166         }
1167
1168         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
1169         btrfs_free_path(path);
1170         *objectid = location.objectid;
1171         return 0;
1172 }
1173
1174 static int btrfs_fill_super(struct super_block *sb,
1175                             struct btrfs_fs_devices *fs_devices,
1176                             void *data)
1177 {
1178         struct inode *inode;
1179         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1180         struct btrfs_key key;
1181         int err;
1182
1183         sb->s_maxbytes = MAX_LFS_FILESIZE;
1184         sb->s_magic = BTRFS_SUPER_MAGIC;
1185         sb->s_op = &btrfs_super_ops;
1186         sb->s_d_op = &btrfs_dentry_operations;
1187         sb->s_export_op = &btrfs_export_ops;
1188         sb->s_xattr = btrfs_xattr_handlers;
1189         sb->s_time_gran = 1;
1190 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
1191         sb->s_flags |= SB_POSIXACL;
1192 #endif
1193         sb->s_flags |= SB_I_VERSION;
1194         sb->s_iflags |= SB_I_CGROUPWB;
1195
1196         err = super_setup_bdi(sb);
1197         if (err) {
1198                 btrfs_err(fs_info, "super_setup_bdi failed");
1199                 return err;
1200         }
1201
1202         err = open_ctree(sb, fs_devices, (char *)data);
1203         if (err) {
1204                 btrfs_err(fs_info, "open_ctree failed");
1205                 return err;
1206         }
1207
1208         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
1209         key.type = BTRFS_INODE_ITEM_KEY;
1210         key.offset = 0;
1211         inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
1212         if (IS_ERR(inode)) {
1213                 err = PTR_ERR(inode);
1214                 goto fail_close;
1215         }
1216
1217         sb->s_root = d_make_root(inode);
1218         if (!sb->s_root) {
1219                 err = -ENOMEM;
1220                 goto fail_close;
1221         }
1222
1223         cleancache_init_fs(sb);
1224         sb->s_flags |= SB_ACTIVE;
1225         return 0;
1226
1227 fail_close:
1228         close_ctree(fs_info);
1229         return err;
1230 }
1231
1232 int btrfs_sync_fs(struct super_block *sb, int wait)
1233 {
1234         struct btrfs_trans_handle *trans;
1235         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1236         struct btrfs_root *root = fs_info->tree_root;
1237
1238         trace_btrfs_sync_fs(fs_info, wait);
1239
1240         if (!wait) {
1241                 filemap_flush(fs_info->btree_inode->i_mapping);
1242                 return 0;
1243         }
1244
1245         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
1246
1247         trans = btrfs_attach_transaction_barrier(root);
1248         if (IS_ERR(trans)) {
1249                 /* no transaction, don't bother */
1250                 if (PTR_ERR(trans) == -ENOENT) {
1251                         /*
1252                          * Exit unless we have some pending changes
1253                          * that need to go through commit
1254                          */
1255                         if (fs_info->pending_changes == 0)
1256                                 return 0;
1257                         /*
1258                          * A non-blocking test if the fs is frozen. We must not
1259                          * start a new transaction here otherwise a deadlock
1260                          * happens. The pending operations are delayed to the
1261                          * next commit after thawing.
1262                          */
1263                         if (sb_start_write_trylock(sb))
1264                                 sb_end_write(sb);
1265                         else
1266                                 return 0;
1267                         trans = btrfs_start_transaction(root, 0);
1268                 }
1269                 if (IS_ERR(trans))
1270                         return PTR_ERR(trans);
1271         }
1272         return btrfs_commit_transaction(trans);
1273 }
1274
1275 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1276 {
1277         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1278         const char *compress_type;
1279
1280         if (btrfs_test_opt(info, DEGRADED))
1281                 seq_puts(seq, ",degraded");
1282         if (btrfs_test_opt(info, NODATASUM))
1283                 seq_puts(seq, ",nodatasum");
1284         if (btrfs_test_opt(info, NODATACOW))
1285                 seq_puts(seq, ",nodatacow");
1286         if (btrfs_test_opt(info, NOBARRIER))
1287                 seq_puts(seq, ",nobarrier");
1288         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1289                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
1290         if (info->thread_pool_size !=  min_t(unsigned long,
1291                                              num_online_cpus() + 2, 8))
1292                 seq_printf(seq, ",thread_pool=%u", info->thread_pool_size);
1293         if (btrfs_test_opt(info, COMPRESS)) {
1294                 compress_type = btrfs_compress_type2str(info->compress_type);
1295                 if (btrfs_test_opt(info, FORCE_COMPRESS))
1296                         seq_printf(seq, ",compress-force=%s", compress_type);
1297                 else
1298                         seq_printf(seq, ",compress=%s", compress_type);
1299                 if (info->compress_level)
1300                         seq_printf(seq, ":%d", info->compress_level);
1301         }
1302         if (btrfs_test_opt(info, NOSSD))
1303                 seq_puts(seq, ",nossd");
1304         if (btrfs_test_opt(info, SSD_SPREAD))
1305                 seq_puts(seq, ",ssd_spread");
1306         else if (btrfs_test_opt(info, SSD))
1307                 seq_puts(seq, ",ssd");
1308         if (btrfs_test_opt(info, NOTREELOG))
1309                 seq_puts(seq, ",notreelog");
1310         if (btrfs_test_opt(info, NOLOGREPLAY))
1311                 seq_puts(seq, ",nologreplay");
1312         if (btrfs_test_opt(info, FLUSHONCOMMIT))
1313                 seq_puts(seq, ",flushoncommit");
1314         if (btrfs_test_opt(info, DISCARD))
1315                 seq_puts(seq, ",discard");
1316         if (!(info->sb->s_flags & SB_POSIXACL))
1317                 seq_puts(seq, ",noacl");
1318         if (btrfs_test_opt(info, SPACE_CACHE))
1319                 seq_puts(seq, ",space_cache");
1320         else if (btrfs_test_opt(info, FREE_SPACE_TREE))
1321                 seq_puts(seq, ",space_cache=v2");
1322         else
1323                 seq_puts(seq, ",nospace_cache");
1324         if (btrfs_test_opt(info, RESCAN_UUID_TREE))
1325                 seq_puts(seq, ",rescan_uuid_tree");
1326         if (btrfs_test_opt(info, CLEAR_CACHE))
1327                 seq_puts(seq, ",clear_cache");
1328         if (btrfs_test_opt(info, USER_SUBVOL_RM_ALLOWED))
1329                 seq_puts(seq, ",user_subvol_rm_allowed");
1330         if (btrfs_test_opt(info, ENOSPC_DEBUG))
1331                 seq_puts(seq, ",enospc_debug");
1332         if (btrfs_test_opt(info, AUTO_DEFRAG))
1333                 seq_puts(seq, ",autodefrag");
1334         if (btrfs_test_opt(info, INODE_MAP_CACHE))
1335                 seq_puts(seq, ",inode_cache");
1336         if (btrfs_test_opt(info, SKIP_BALANCE))
1337                 seq_puts(seq, ",skip_balance");
1338 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1339         if (btrfs_test_opt(info, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
1340                 seq_puts(seq, ",check_int_data");
1341         else if (btrfs_test_opt(info, CHECK_INTEGRITY))
1342                 seq_puts(seq, ",check_int");
1343         if (info->check_integrity_print_mask)
1344                 seq_printf(seq, ",check_int_print_mask=%d",
1345                                 info->check_integrity_print_mask);
1346 #endif
1347         if (info->metadata_ratio)
1348                 seq_printf(seq, ",metadata_ratio=%u", info->metadata_ratio);
1349         if (btrfs_test_opt(info, PANIC_ON_FATAL_ERROR))
1350                 seq_puts(seq, ",fatal_errors=panic");
1351         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1352                 seq_printf(seq, ",commit=%u", info->commit_interval);
1353 #ifdef CONFIG_BTRFS_DEBUG
1354         if (btrfs_test_opt(info, FRAGMENT_DATA))
1355                 seq_puts(seq, ",fragment=data");
1356         if (btrfs_test_opt(info, FRAGMENT_METADATA))
1357                 seq_puts(seq, ",fragment=metadata");
1358 #endif
1359         if (btrfs_test_opt(info, REF_VERIFY))
1360                 seq_puts(seq, ",ref_verify");
1361         seq_printf(seq, ",subvolid=%llu",
1362                   BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1363         seq_puts(seq, ",subvol=");
1364         seq_dentry(seq, dentry, " \t\n\\");
1365         return 0;
1366 }
1367
1368 static int btrfs_test_super(struct super_block *s, void *data)
1369 {
1370         struct btrfs_fs_info *p = data;
1371         struct btrfs_fs_info *fs_info = btrfs_sb(s);
1372
1373         return fs_info->fs_devices == p->fs_devices;
1374 }
1375
1376 static int btrfs_set_super(struct super_block *s, void *data)
1377 {
1378         int err = set_anon_super(s, data);
1379         if (!err)
1380                 s->s_fs_info = data;
1381         return err;
1382 }
1383
1384 /*
1385  * subvolumes are identified by ino 256
1386  */
1387 static inline int is_subvolume_inode(struct inode *inode)
1388 {
1389         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1390                 return 1;
1391         return 0;
1392 }
1393
1394 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
1395                                    const char *device_name, struct vfsmount *mnt)
1396 {
1397         struct dentry *root;
1398         int ret;
1399
1400         if (!subvol_name) {
1401                 if (!subvol_objectid) {
1402                         ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
1403                                                           &subvol_objectid);
1404                         if (ret) {
1405                                 root = ERR_PTR(ret);
1406                                 goto out;
1407                         }
1408                 }
1409                 subvol_name = get_subvol_name_from_objectid(btrfs_sb(mnt->mnt_sb),
1410                                                             subvol_objectid);
1411                 if (IS_ERR(subvol_name)) {
1412                         root = ERR_CAST(subvol_name);
1413                         subvol_name = NULL;
1414                         goto out;
1415                 }
1416
1417         }
1418
1419         root = mount_subtree(mnt, subvol_name);
1420         /* mount_subtree() drops our reference on the vfsmount. */
1421         mnt = NULL;
1422
1423         if (!IS_ERR(root)) {
1424                 struct super_block *s = root->d_sb;
1425                 struct btrfs_fs_info *fs_info = btrfs_sb(s);
1426                 struct inode *root_inode = d_inode(root);
1427                 u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
1428
1429                 ret = 0;
1430                 if (!is_subvolume_inode(root_inode)) {
1431                         btrfs_err(fs_info, "'%s' is not a valid subvolume",
1432                                subvol_name);
1433                         ret = -EINVAL;
1434                 }
1435                 if (subvol_objectid && root_objectid != subvol_objectid) {
1436                         /*
1437                          * This will also catch a race condition where a
1438                          * subvolume which was passed by ID is renamed and
1439                          * another subvolume is renamed over the old location.
1440                          */
1441                         btrfs_err(fs_info,
1442                                   "subvol '%s' does not match subvolid %llu",
1443                                   subvol_name, subvol_objectid);
1444                         ret = -EINVAL;
1445                 }
1446                 if (ret) {
1447                         dput(root);
1448                         root = ERR_PTR(ret);
1449                         deactivate_locked_super(s);
1450                 }
1451         }
1452
1453 out:
1454         mntput(mnt);
1455         kfree(subvol_name);
1456         return root;
1457 }
1458
1459 static int parse_security_options(char *orig_opts,
1460                                   struct security_mnt_opts *sec_opts)
1461 {
1462         char *secdata = NULL;
1463         int ret = 0;
1464
1465         secdata = alloc_secdata();
1466         if (!secdata)
1467                 return -ENOMEM;
1468         ret = security_sb_copy_data(orig_opts, secdata);
1469         if (ret) {
1470                 free_secdata(secdata);
1471                 return ret;
1472         }
1473         ret = security_sb_parse_opts_str(secdata, sec_opts);
1474         free_secdata(secdata);
1475         return ret;
1476 }
1477
1478 static int setup_security_options(struct btrfs_fs_info *fs_info,
1479                                   struct super_block *sb,
1480                                   struct security_mnt_opts *sec_opts)
1481 {
1482         int ret = 0;
1483
1484         /*
1485          * Call security_sb_set_mnt_opts() to check whether new sec_opts
1486          * is valid.
1487          */
1488         ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
1489         if (ret)
1490                 return ret;
1491
1492 #ifdef CONFIG_SECURITY
1493         if (!fs_info->security_opts.num_mnt_opts) {
1494                 /* first time security setup, copy sec_opts to fs_info */
1495                 memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts));
1496         } else {
1497                 /*
1498                  * Since SELinux (the only one supporting security_mnt_opts)
1499                  * does NOT support changing context during remount/mount of
1500                  * the same sb, this must be the same or part of the same
1501                  * security options, just free it.
1502                  */
1503                 security_free_mnt_opts(sec_opts);
1504         }
1505 #endif
1506         return ret;
1507 }
1508
1509 /*
1510  * Find a superblock for the given device / mount point.
1511  *
1512  * Note: This is based on mount_bdev from fs/super.c with a few additions
1513  *       for multiple device setup.  Make sure to keep it in sync.
1514  */
1515 static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
1516                 int flags, const char *device_name, void *data)
1517 {
1518         struct block_device *bdev = NULL;
1519         struct super_block *s;
1520         struct btrfs_fs_devices *fs_devices = NULL;
1521         struct btrfs_fs_info *fs_info = NULL;
1522         struct security_mnt_opts new_sec_opts;
1523         fmode_t mode = FMODE_READ;
1524         int error = 0;
1525
1526         if (!(flags & SB_RDONLY))
1527                 mode |= FMODE_WRITE;
1528
1529         error = btrfs_parse_early_options(data, mode, fs_type,
1530                                           &fs_devices);
1531         if (error) {
1532                 return ERR_PTR(error);
1533         }
1534
1535         security_init_mnt_opts(&new_sec_opts);
1536         if (data) {
1537                 error = parse_security_options(data, &new_sec_opts);
1538                 if (error)
1539                         return ERR_PTR(error);
1540         }
1541
1542         mutex_lock(&uuid_mutex);
1543         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1544         mutex_unlock(&uuid_mutex);
1545         if (error)
1546                 goto error_sec_opts;
1547
1548         /*
1549          * Setup a dummy root and fs_info for test/set super.  This is because
1550          * we don't actually fill this stuff out until open_ctree, but we need
1551          * it for searching for existing supers, so this lets us do that and
1552          * then open_ctree will properly initialize everything later.
1553          */
1554         fs_info = kvzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
1555         if (!fs_info) {
1556                 error = -ENOMEM;
1557                 goto error_sec_opts;
1558         }
1559
1560         fs_info->fs_devices = fs_devices;
1561
1562         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1563         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1564         security_init_mnt_opts(&fs_info->security_opts);
1565         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1566                 error = -ENOMEM;
1567                 goto error_fs_info;
1568         }
1569
1570         error = btrfs_open_devices(fs_devices, mode, fs_type);
1571         if (error)
1572                 goto error_fs_info;
1573
1574         if (!(flags & SB_RDONLY) && fs_devices->rw_devices == 0) {
1575                 error = -EACCES;
1576                 goto error_close_devices;
1577         }
1578
1579         bdev = fs_devices->latest_bdev;
1580         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | SB_NOSEC,
1581                  fs_info);
1582         if (IS_ERR(s)) {
1583                 error = PTR_ERR(s);
1584                 goto error_close_devices;
1585         }
1586
1587         if (s->s_root) {
1588                 btrfs_close_devices(fs_devices);
1589                 free_fs_info(fs_info);
1590                 if ((flags ^ s->s_flags) & SB_RDONLY)
1591                         error = -EBUSY;
1592         } else {
1593                 snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
1594                 btrfs_sb(s)->bdev_holder = fs_type;
1595                 error = btrfs_fill_super(s, fs_devices, data);
1596         }
1597         if (error) {
1598                 deactivate_locked_super(s);
1599                 goto error_sec_opts;
1600         }
1601
1602         fs_info = btrfs_sb(s);
1603         error = setup_security_options(fs_info, s, &new_sec_opts);
1604         if (error) {
1605                 deactivate_locked_super(s);
1606                 goto error_sec_opts;
1607         }
1608
1609         return dget(s->s_root);
1610
1611 error_close_devices:
1612         btrfs_close_devices(fs_devices);
1613 error_fs_info:
1614         free_fs_info(fs_info);
1615 error_sec_opts:
1616         security_free_mnt_opts(&new_sec_opts);
1617         return ERR_PTR(error);
1618 }
1619
1620 /*
1621  * Mount function which is called by VFS layer.
1622  *
1623  * In order to allow mounting a subvolume directly, btrfs uses mount_subtree()
1624  * which needs vfsmount* of device's root (/).  This means device's root has to
1625  * be mounted internally in any case.
1626  *
1627  * Operation flow:
1628  *   1. Parse subvol id related options for later use in mount_subvol().
1629  *
1630  *   2. Mount device's root (/) by calling vfs_kern_mount().
1631  *
1632  *      NOTE: vfs_kern_mount() is used by VFS to call btrfs_mount() in the
1633  *      first place. In order to avoid calling btrfs_mount() again, we use
1634  *      different file_system_type which is not registered to VFS by
1635  *      register_filesystem() (btrfs_root_fs_type). As a result,
1636  *      btrfs_mount_root() is called. The return value will be used by
1637  *      mount_subtree() in mount_subvol().
1638  *
1639  *   3. Call mount_subvol() to get the dentry of subvolume. Since there is
1640  *      "btrfs subvolume set-default", mount_subvol() is called always.
1641  */
1642 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1643                 const char *device_name, void *data)
1644 {
1645         struct vfsmount *mnt_root;
1646         struct dentry *root;
1647         fmode_t mode = FMODE_READ;
1648         char *subvol_name = NULL;
1649         u64 subvol_objectid = 0;
1650         int error = 0;
1651
1652         if (!(flags & SB_RDONLY))
1653                 mode |= FMODE_WRITE;
1654
1655         error = btrfs_parse_subvol_options(data, &subvol_name,
1656                                         &subvol_objectid);
1657         if (error) {
1658                 kfree(subvol_name);
1659                 return ERR_PTR(error);
1660         }
1661
1662         /* mount device's root (/) */
1663         mnt_root = vfs_kern_mount(&btrfs_root_fs_type, flags, device_name, data);
1664         if (PTR_ERR_OR_ZERO(mnt_root) == -EBUSY) {
1665                 if (flags & SB_RDONLY) {
1666                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1667                                 flags & ~SB_RDONLY, device_name, data);
1668                 } else {
1669                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1670                                 flags | SB_RDONLY, device_name, data);
1671                         if (IS_ERR(mnt_root)) {
1672                                 root = ERR_CAST(mnt_root);
1673                                 goto out;
1674                         }
1675
1676                         down_write(&mnt_root->mnt_sb->s_umount);
1677                         error = btrfs_remount(mnt_root->mnt_sb, &flags, NULL);
1678                         up_write(&mnt_root->mnt_sb->s_umount);
1679                         if (error < 0) {
1680                                 root = ERR_PTR(error);
1681                                 mntput(mnt_root);
1682                                 goto out;
1683                         }
1684                 }
1685         }
1686         if (IS_ERR(mnt_root)) {
1687                 root = ERR_CAST(mnt_root);
1688                 goto out;
1689         }
1690
1691         /* mount_subvol() will free subvol_name and mnt_root */
1692         root = mount_subvol(subvol_name, subvol_objectid, device_name, mnt_root);
1693
1694 out:
1695         return root;
1696 }
1697
1698 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1699                                      u32 new_pool_size, u32 old_pool_size)
1700 {
1701         if (new_pool_size == old_pool_size)
1702                 return;
1703
1704         fs_info->thread_pool_size = new_pool_size;
1705
1706         btrfs_info(fs_info, "resize thread pool %d -> %d",
1707                old_pool_size, new_pool_size);
1708
1709         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1710         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1711         btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);
1712         btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1713         btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
1714         btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
1715         btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
1716                                 new_pool_size);
1717         btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1718         btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1719         btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1720         btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
1721         btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
1722                                 new_pool_size);
1723 }
1724
1725 static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
1726 {
1727         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1728 }
1729
1730 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1731                                        unsigned long old_opts, int flags)
1732 {
1733         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1734             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1735              (flags & SB_RDONLY))) {
1736                 /* wait for any defraggers to finish */
1737                 wait_event(fs_info->transaction_wait,
1738                            (atomic_read(&fs_info->defrag_running) == 0));
1739                 if (flags & SB_RDONLY)
1740                         sync_filesystem(fs_info->sb);
1741         }
1742 }
1743
1744 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1745                                          unsigned long old_opts)
1746 {
1747         /*
1748          * We need to cleanup all defragable inodes if the autodefragment is
1749          * close or the filesystem is read only.
1750          */
1751         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1752             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) || sb_rdonly(fs_info->sb))) {
1753                 btrfs_cleanup_defrag_inodes(fs_info);
1754         }
1755
1756         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1757 }
1758
1759 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1760 {
1761         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1762         struct btrfs_root *root = fs_info->tree_root;
1763         unsigned old_flags = sb->s_flags;
1764         unsigned long old_opts = fs_info->mount_opt;
1765         unsigned long old_compress_type = fs_info->compress_type;
1766         u64 old_max_inline = fs_info->max_inline;
1767         u32 old_thread_pool_size = fs_info->thread_pool_size;
1768         u32 old_metadata_ratio = fs_info->metadata_ratio;
1769         int ret;
1770
1771         sync_filesystem(sb);
1772         btrfs_remount_prepare(fs_info);
1773
1774         if (data) {
1775                 struct security_mnt_opts new_sec_opts;
1776
1777                 security_init_mnt_opts(&new_sec_opts);
1778                 ret = parse_security_options(data, &new_sec_opts);
1779                 if (ret)
1780                         goto restore;
1781                 ret = setup_security_options(fs_info, sb,
1782                                              &new_sec_opts);
1783                 if (ret) {
1784                         security_free_mnt_opts(&new_sec_opts);
1785                         goto restore;
1786                 }
1787         }
1788
1789         ret = btrfs_parse_options(fs_info, data, *flags);
1790         if (ret)
1791                 goto restore;
1792
1793         btrfs_remount_begin(fs_info, old_opts, *flags);
1794         btrfs_resize_thread_pool(fs_info,
1795                 fs_info->thread_pool_size, old_thread_pool_size);
1796
1797         if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
1798                 goto out;
1799
1800         if (*flags & SB_RDONLY) {
1801                 /*
1802                  * this also happens on 'umount -rf' or on shutdown, when
1803                  * the filesystem is busy.
1804                  */
1805                 cancel_work_sync(&fs_info->async_reclaim_work);
1806
1807                 /* wait for the uuid_scan task to finish */
1808                 down(&fs_info->uuid_tree_rescan_sem);
1809                 /* avoid complains from lockdep et al. */
1810                 up(&fs_info->uuid_tree_rescan_sem);
1811
1812                 sb->s_flags |= SB_RDONLY;
1813
1814                 /*
1815                  * Setting SB_RDONLY will put the cleaner thread to
1816                  * sleep at the next loop if it's already active.
1817                  * If it's already asleep, we'll leave unused block
1818                  * groups on disk until we're mounted read-write again
1819                  * unless we clean them up here.
1820                  */
1821                 btrfs_delete_unused_bgs(fs_info);
1822
1823                 btrfs_dev_replace_suspend_for_unmount(fs_info);
1824                 btrfs_scrub_cancel(fs_info);
1825                 btrfs_pause_balance(fs_info);
1826
1827                 ret = btrfs_commit_super(fs_info);
1828                 if (ret)
1829                         goto restore;
1830         } else {
1831                 if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
1832                         btrfs_err(fs_info,
1833                                 "Remounting read-write after error is not allowed");
1834                         ret = -EINVAL;
1835                         goto restore;
1836                 }
1837                 if (fs_info->fs_devices->rw_devices == 0) {
1838                         ret = -EACCES;
1839                         goto restore;
1840                 }
1841
1842                 if (!btrfs_check_rw_degradable(fs_info, NULL)) {
1843                         btrfs_warn(fs_info,
1844                                 "too many missing devices, writeable remount is not allowed");
1845                         ret = -EACCES;
1846                         goto restore;
1847                 }
1848
1849                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1850                         ret = -EINVAL;
1851                         goto restore;
1852                 }
1853
1854                 ret = btrfs_cleanup_fs_roots(fs_info);
1855                 if (ret)
1856                         goto restore;
1857
1858                 /* recover relocation */
1859                 mutex_lock(&fs_info->cleaner_mutex);
1860                 ret = btrfs_recover_relocation(root);
1861                 mutex_unlock(&fs_info->cleaner_mutex);
1862                 if (ret)
1863                         goto restore;
1864
1865                 ret = btrfs_resume_balance_async(fs_info);
1866                 if (ret)
1867                         goto restore;
1868
1869                 ret = btrfs_resume_dev_replace_async(fs_info);
1870                 if (ret) {
1871                         btrfs_warn(fs_info, "failed to resume dev_replace");
1872                         goto restore;
1873                 }
1874
1875                 btrfs_qgroup_rescan_resume(fs_info);
1876
1877                 if (!fs_info->uuid_root) {
1878                         btrfs_info(fs_info, "creating UUID tree");
1879                         ret = btrfs_create_uuid_tree(fs_info);
1880                         if (ret) {
1881                                 btrfs_warn(fs_info,
1882                                            "failed to create the UUID tree %d",
1883                                            ret);
1884                                 goto restore;
1885                         }
1886                 }
1887                 sb->s_flags &= ~SB_RDONLY;
1888
1889                 set_bit(BTRFS_FS_OPEN, &fs_info->flags);
1890         }
1891 out:
1892         wake_up_process(fs_info->transaction_kthread);
1893         btrfs_remount_cleanup(fs_info, old_opts);
1894         return 0;
1895
1896 restore:
1897         /* We've hit an error - don't reset SB_RDONLY */
1898         if (sb_rdonly(sb))
1899                 old_flags |= SB_RDONLY;
1900         sb->s_flags = old_flags;
1901         fs_info->mount_opt = old_opts;
1902         fs_info->compress_type = old_compress_type;
1903         fs_info->max_inline = old_max_inline;
1904         btrfs_resize_thread_pool(fs_info,
1905                 old_thread_pool_size, fs_info->thread_pool_size);
1906         fs_info->metadata_ratio = old_metadata_ratio;
1907         btrfs_remount_cleanup(fs_info, old_opts);
1908         return ret;
1909 }
1910
1911 /* Used to sort the devices by max_avail(descending sort) */
1912 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1913                                        const void *dev_info2)
1914 {
1915         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1916             ((struct btrfs_device_info *)dev_info2)->max_avail)
1917                 return -1;
1918         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1919                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1920                 return 1;
1921         else
1922         return 0;
1923 }
1924
1925 /*
1926  * sort the devices by max_avail, in which max free extent size of each device
1927  * is stored.(Descending Sort)
1928  */
1929 static inline void btrfs_descending_sort_devices(
1930                                         struct btrfs_device_info *devices,
1931                                         size_t nr_devices)
1932 {
1933         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1934              btrfs_cmp_device_free_bytes, NULL);
1935 }
1936
1937 /*
1938  * The helper to calc the free space on the devices that can be used to store
1939  * file data.
1940  */
1941 static int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
1942                                        u64 *free_bytes)
1943 {
1944         struct btrfs_device_info *devices_info;
1945         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1946         struct btrfs_device *device;
1947         u64 skip_space;
1948         u64 type;
1949         u64 avail_space;
1950         u64 min_stripe_size;
1951         int min_stripes = 1, num_stripes = 1;
1952         int i = 0, nr_devices;
1953
1954         /*
1955          * We aren't under the device list lock, so this is racy-ish, but good
1956          * enough for our purposes.
1957          */
1958         nr_devices = fs_info->fs_devices->open_devices;
1959         if (!nr_devices) {
1960                 smp_mb();
1961                 nr_devices = fs_info->fs_devices->open_devices;
1962                 ASSERT(nr_devices);
1963                 if (!nr_devices) {
1964                         *free_bytes = 0;
1965                         return 0;
1966                 }
1967         }
1968
1969         devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
1970                                GFP_KERNEL);
1971         if (!devices_info)
1972                 return -ENOMEM;
1973
1974         /* calc min stripe number for data space allocation */
1975         type = btrfs_data_alloc_profile(fs_info);
1976         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1977                 min_stripes = 2;
1978                 num_stripes = nr_devices;
1979         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1980                 min_stripes = 2;
1981                 num_stripes = 2;
1982         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1983                 min_stripes = 4;
1984                 num_stripes = 4;
1985         }
1986
1987         if (type & BTRFS_BLOCK_GROUP_DUP)
1988                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1989         else
1990                 min_stripe_size = BTRFS_STRIPE_LEN;
1991
1992         rcu_read_lock();
1993         list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
1994                 if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
1995                                                 &device->dev_state) ||
1996                     !device->bdev ||
1997                     test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
1998                         continue;
1999
2000                 if (i >= nr_devices)
2001                         break;
2002
2003                 avail_space = device->total_bytes - device->bytes_used;
2004
2005                 /* align with stripe_len */
2006                 avail_space = div_u64(avail_space, BTRFS_STRIPE_LEN);
2007                 avail_space *= BTRFS_STRIPE_LEN;
2008
2009                 /*
2010                  * In order to avoid overwriting the superblock on the drive,
2011                  * btrfs starts at an offset of at least 1MB when doing chunk
2012                  * allocation.
2013                  */
2014                 skip_space = SZ_1M;
2015
2016                 /*
2017                  * we can use the free space in [0, skip_space - 1], subtract
2018                  * it from the total.
2019                  */
2020                 if (avail_space && avail_space >= skip_space)
2021                         avail_space -= skip_space;
2022                 else
2023                         avail_space = 0;
2024
2025                 if (avail_space < min_stripe_size)
2026                         continue;
2027
2028                 devices_info[i].dev = device;
2029                 devices_info[i].max_avail = avail_space;
2030
2031                 i++;
2032         }
2033         rcu_read_unlock();
2034
2035         nr_devices = i;
2036
2037         btrfs_descending_sort_devices(devices_info, nr_devices);
2038
2039         i = nr_devices - 1;
2040         avail_space = 0;
2041         while (nr_devices >= min_stripes) {
2042                 if (num_stripes > nr_devices)
2043                         num_stripes = nr_devices;
2044
2045                 if (devices_info[i].max_avail >= min_stripe_size) {
2046                         int j;
2047                         u64 alloc_size;
2048
2049                         avail_space += devices_info[i].max_avail * num_stripes;
2050                         alloc_size = devices_info[i].max_avail;
2051                         for (j = i + 1 - num_stripes; j <= i; j++)
2052                                 devices_info[j].max_avail -= alloc_size;
2053                 }
2054                 i--;
2055                 nr_devices--;
2056         }
2057
2058         kfree(devices_info);
2059         *free_bytes = avail_space;
2060         return 0;
2061 }
2062
2063 /*
2064  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
2065  *
2066  * If there's a redundant raid level at DATA block groups, use the respective
2067  * multiplier to scale the sizes.
2068  *
2069  * Unused device space usage is based on simulating the chunk allocator
2070  * algorithm that respects the device sizes and order of allocations.  This is
2071  * a close approximation of the actual use but there are other factors that may
2072  * change the result (like a new metadata chunk).
2073  *
2074  * If metadata is exhausted, f_bavail will be 0.
2075  */
2076 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
2077 {
2078         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
2079         struct btrfs_super_block *disk_super = fs_info->super_copy;
2080         struct list_head *head = &fs_info->space_info;
2081         struct btrfs_space_info *found;
2082         u64 total_used = 0;
2083         u64 total_free_data = 0;
2084         u64 total_free_meta = 0;
2085         int bits = dentry->d_sb->s_blocksize_bits;
2086         __be32 *fsid = (__be32 *)fs_info->fsid;
2087         unsigned factor = 1;
2088         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
2089         int ret;
2090         u64 thresh = 0;
2091         int mixed = 0;
2092
2093         rcu_read_lock();
2094         list_for_each_entry_rcu(found, head, list) {
2095                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
2096                         int i;
2097
2098                         total_free_data += found->disk_total - found->disk_used;
2099                         total_free_data -=
2100                                 btrfs_account_ro_block_groups_free_space(found);
2101
2102                         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
2103                                 if (!list_empty(&found->block_groups[i])) {
2104                                         switch (i) {
2105                                         case BTRFS_RAID_DUP:
2106                                         case BTRFS_RAID_RAID1:
2107                                         case BTRFS_RAID_RAID10:
2108                                                 factor = 2;
2109                                         }
2110                                 }
2111                         }
2112                 }
2113
2114                 /*
2115                  * Metadata in mixed block goup profiles are accounted in data
2116                  */
2117                 if (!mixed && found->flags & BTRFS_BLOCK_GROUP_METADATA) {
2118                         if (found->flags & BTRFS_BLOCK_GROUP_DATA)
2119                                 mixed = 1;
2120                         else
2121                                 total_free_meta += found->disk_total -
2122                                         found->disk_used;
2123                 }
2124
2125                 total_used += found->disk_used;
2126         }
2127
2128         rcu_read_unlock();
2129
2130         buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
2131         buf->f_blocks >>= bits;
2132         buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
2133
2134         /* Account global block reserve as used, it's in logical size already */
2135         spin_lock(&block_rsv->lock);
2136         /* Mixed block groups accounting is not byte-accurate, avoid overflow */
2137         if (buf->f_bfree >= block_rsv->size >> bits)
2138                 buf->f_bfree -= block_rsv->size >> bits;
2139         else
2140                 buf->f_bfree = 0;
2141         spin_unlock(&block_rsv->lock);
2142
2143         buf->f_bavail = div_u64(total_free_data, factor);
2144         ret = btrfs_calc_avail_data_space(fs_info, &total_free_data);
2145         if (ret)
2146                 return ret;
2147         buf->f_bavail += div_u64(total_free_data, factor);
2148         buf->f_bavail = buf->f_bavail >> bits;
2149
2150         /*
2151          * We calculate the remaining metadata space minus global reserve. If
2152          * this is (supposedly) smaller than zero, there's no space. But this
2153          * does not hold in practice, the exhausted state happens where's still
2154          * some positive delta. So we apply some guesswork and compare the
2155          * delta to a 4M threshold.  (Practically observed delta was ~2M.)
2156          *
2157          * We probably cannot calculate the exact threshold value because this
2158          * depends on the internal reservations requested by various
2159          * operations, so some operations that consume a few metadata will
2160          * succeed even if the Avail is zero. But this is better than the other
2161          * way around.
2162          */
2163         thresh = SZ_4M;
2164
2165         if (!mixed && total_free_meta - thresh < block_rsv->size)
2166                 buf->f_bavail = 0;
2167
2168         buf->f_type = BTRFS_SUPER_MAGIC;
2169         buf->f_bsize = dentry->d_sb->s_blocksize;
2170         buf->f_namelen = BTRFS_NAME_LEN;
2171
2172         /* We treat it as constant endianness (it doesn't matter _which_)
2173            because we want the fsid to come out the same whether mounted
2174            on a big-endian or little-endian host */
2175         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
2176         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
2177         /* Mask in the root object ID too, to disambiguate subvols */
2178         buf->f_fsid.val[0] ^= BTRFS_I(d_inode(dentry))->root->objectid >> 32;
2179         buf->f_fsid.val[1] ^= BTRFS_I(d_inode(dentry))->root->objectid;
2180
2181         return 0;
2182 }
2183
2184 static void btrfs_kill_super(struct super_block *sb)
2185 {
2186         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2187         kill_anon_super(sb);
2188         free_fs_info(fs_info);
2189 }
2190
2191 static struct file_system_type btrfs_fs_type = {
2192         .owner          = THIS_MODULE,
2193         .name           = "btrfs",
2194         .mount          = btrfs_mount,
2195         .kill_sb        = btrfs_kill_super,
2196         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2197 };
2198
2199 static struct file_system_type btrfs_root_fs_type = {
2200         .owner          = THIS_MODULE,
2201         .name           = "btrfs",
2202         .mount          = btrfs_mount_root,
2203         .kill_sb        = btrfs_kill_super,
2204         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2205 };
2206
2207 MODULE_ALIAS_FS("btrfs");
2208
2209 static int btrfs_control_open(struct inode *inode, struct file *file)
2210 {
2211         /*
2212          * The control file's private_data is used to hold the
2213          * transaction when it is started and is used to keep
2214          * track of whether a transaction is already in progress.
2215          */
2216         file->private_data = NULL;
2217         return 0;
2218 }
2219
2220 /*
2221  * used by btrfsctl to scan devices when no FS is mounted
2222  */
2223 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
2224                                 unsigned long arg)
2225 {
2226         struct btrfs_ioctl_vol_args *vol;
2227         struct btrfs_fs_devices *fs_devices;
2228         int ret = -ENOTTY;
2229
2230         if (!capable(CAP_SYS_ADMIN))
2231                 return -EPERM;
2232
2233         vol = memdup_user((void __user *)arg, sizeof(*vol));
2234         if (IS_ERR(vol))
2235                 return PTR_ERR(vol);
2236
2237         switch (cmd) {
2238         case BTRFS_IOC_SCAN_DEV:
2239                 mutex_lock(&uuid_mutex);
2240                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2241                                             &btrfs_root_fs_type, &fs_devices);
2242                 mutex_unlock(&uuid_mutex);
2243                 break;
2244         case BTRFS_IOC_DEVICES_READY:
2245                 mutex_lock(&uuid_mutex);
2246                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2247                                             &btrfs_root_fs_type, &fs_devices);
2248                 if (ret) {
2249                         mutex_unlock(&uuid_mutex);
2250                         break;
2251                 }
2252                 ret = !(fs_devices->num_devices == fs_devices->total_devices);
2253                 mutex_unlock(&uuid_mutex);
2254                 break;
2255         case BTRFS_IOC_GET_SUPPORTED_FEATURES:
2256                 ret = btrfs_ioctl_get_supported_features((void __user*)arg);
2257                 break;
2258         }
2259
2260         kfree(vol);
2261         return ret;
2262 }
2263
2264 static int btrfs_freeze(struct super_block *sb)
2265 {
2266         struct btrfs_trans_handle *trans;
2267         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2268         struct btrfs_root *root = fs_info->tree_root;
2269
2270         set_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2271         /*
2272          * We don't need a barrier here, we'll wait for any transaction that
2273          * could be in progress on other threads (and do delayed iputs that
2274          * we want to avoid on a frozen filesystem), or do the commit
2275          * ourselves.
2276          */
2277         trans = btrfs_attach_transaction_barrier(root);
2278         if (IS_ERR(trans)) {
2279                 /* no transaction, don't bother */
2280                 if (PTR_ERR(trans) == -ENOENT)
2281                         return 0;
2282                 return PTR_ERR(trans);
2283         }
2284         return btrfs_commit_transaction(trans);
2285 }
2286
2287 static int btrfs_unfreeze(struct super_block *sb)
2288 {
2289         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2290
2291         clear_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2292         return 0;
2293 }
2294
2295 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
2296 {
2297         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
2298         struct btrfs_fs_devices *cur_devices;
2299         struct btrfs_device *dev, *first_dev = NULL;
2300         struct list_head *head;
2301         struct rcu_string *name;
2302
2303         /*
2304          * Lightweight locking of the devices. We should not need
2305          * device_list_mutex here as we only read the device data and the list
2306          * is protected by RCU.  Even if a device is deleted during the list
2307          * traversals, we'll get valid data, the freeing callback will wait at
2308          * least until until the rcu_read_unlock.
2309          */
2310         rcu_read_lock();
2311         cur_devices = fs_info->fs_devices;
2312         while (cur_devices) {
2313                 head = &cur_devices->devices;
2314                 list_for_each_entry_rcu(dev, head, dev_list) {
2315                         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state))
2316                                 continue;
2317                         if (!dev->name)
2318                                 continue;
2319                         if (!first_dev || dev->devid < first_dev->devid)
2320                                 first_dev = dev;
2321                 }
2322                 cur_devices = cur_devices->seed;
2323         }
2324
2325         if (first_dev) {
2326                 name = rcu_dereference(first_dev->name);
2327                 seq_escape(m, name->str, " \t\n\\");
2328         } else {
2329                 WARN_ON(1);
2330         }
2331         rcu_read_unlock();
2332         return 0;
2333 }
2334
2335 static const struct super_operations btrfs_super_ops = {
2336         .drop_inode     = btrfs_drop_inode,
2337         .evict_inode    = btrfs_evict_inode,
2338         .put_super      = btrfs_put_super,
2339         .sync_fs        = btrfs_sync_fs,
2340         .show_options   = btrfs_show_options,
2341         .show_devname   = btrfs_show_devname,
2342         .write_inode    = btrfs_write_inode,
2343         .alloc_inode    = btrfs_alloc_inode,
2344         .destroy_inode  = btrfs_destroy_inode,
2345         .statfs         = btrfs_statfs,
2346         .remount_fs     = btrfs_remount,
2347         .freeze_fs      = btrfs_freeze,
2348         .unfreeze_fs    = btrfs_unfreeze,
2349 };
2350
2351 static const struct file_operations btrfs_ctl_fops = {
2352         .open = btrfs_control_open,
2353         .unlocked_ioctl  = btrfs_control_ioctl,
2354         .compat_ioctl = btrfs_control_ioctl,
2355         .owner   = THIS_MODULE,
2356         .llseek = noop_llseek,
2357 };
2358
2359 static struct miscdevice btrfs_misc = {
2360         .minor          = BTRFS_MINOR,
2361         .name           = "btrfs-control",
2362         .fops           = &btrfs_ctl_fops
2363 };
2364
2365 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2366 MODULE_ALIAS("devname:btrfs-control");
2367
2368 static int __init btrfs_interface_init(void)
2369 {
2370         return misc_register(&btrfs_misc);
2371 }
2372
2373 static __cold void btrfs_interface_exit(void)
2374 {
2375         misc_deregister(&btrfs_misc);
2376 }
2377
2378 static void __init btrfs_print_mod_info(void)
2379 {
2380         static const char options[] = ""
2381 #ifdef CONFIG_BTRFS_DEBUG
2382                         ", debug=on"
2383 #endif
2384 #ifdef CONFIG_BTRFS_ASSERT
2385                         ", assert=on"
2386 #endif
2387 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2388                         ", integrity-checker=on"
2389 #endif
2390 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
2391                         ", ref-verify=on"
2392 #endif
2393                         ;
2394         pr_info("Btrfs loaded, crc32c=%s%s\n", crc32c_impl(), options);
2395 }
2396
2397 static int __init init_btrfs_fs(void)
2398 {
2399         int err;
2400
2401         btrfs_props_init();
2402
2403         err = btrfs_init_sysfs();
2404         if (err)
2405                 return err;
2406
2407         btrfs_init_compress();
2408
2409         err = btrfs_init_cachep();
2410         if (err)
2411                 goto free_compress;
2412
2413         err = extent_io_init();
2414         if (err)
2415                 goto free_cachep;
2416
2417         err = extent_map_init();
2418         if (err)
2419                 goto free_extent_io;
2420
2421         err = ordered_data_init();
2422         if (err)
2423                 goto free_extent_map;
2424
2425         err = btrfs_delayed_inode_init();
2426         if (err)
2427                 goto free_ordered_data;
2428
2429         err = btrfs_auto_defrag_init();
2430         if (err)
2431                 goto free_delayed_inode;
2432
2433         err = btrfs_delayed_ref_init();
2434         if (err)
2435                 goto free_auto_defrag;
2436
2437         err = btrfs_prelim_ref_init();
2438         if (err)
2439                 goto free_delayed_ref;
2440
2441         err = btrfs_end_io_wq_init();
2442         if (err)
2443                 goto free_prelim_ref;
2444
2445         err = btrfs_interface_init();
2446         if (err)
2447                 goto free_end_io_wq;
2448
2449         btrfs_init_lockdep();
2450
2451         btrfs_print_mod_info();
2452
2453         err = btrfs_run_sanity_tests();
2454         if (err)
2455                 goto unregister_ioctl;
2456
2457         err = register_filesystem(&btrfs_fs_type);
2458         if (err)
2459                 goto unregister_ioctl;
2460
2461         return 0;
2462
2463 unregister_ioctl:
2464         btrfs_interface_exit();
2465 free_end_io_wq:
2466         btrfs_end_io_wq_exit();
2467 free_prelim_ref:
2468         btrfs_prelim_ref_exit();
2469 free_delayed_ref:
2470         btrfs_delayed_ref_exit();
2471 free_auto_defrag:
2472         btrfs_auto_defrag_exit();
2473 free_delayed_inode:
2474         btrfs_delayed_inode_exit();
2475 free_ordered_data:
2476         ordered_data_exit();
2477 free_extent_map:
2478         extent_map_exit();
2479 free_extent_io:
2480         extent_io_exit();
2481 free_cachep:
2482         btrfs_destroy_cachep();
2483 free_compress:
2484         btrfs_exit_compress();
2485         btrfs_exit_sysfs();
2486
2487         return err;
2488 }
2489
2490 static void __exit exit_btrfs_fs(void)
2491 {
2492         btrfs_destroy_cachep();
2493         btrfs_delayed_ref_exit();
2494         btrfs_auto_defrag_exit();
2495         btrfs_delayed_inode_exit();
2496         btrfs_prelim_ref_exit();
2497         ordered_data_exit();
2498         extent_map_exit();
2499         extent_io_exit();
2500         btrfs_interface_exit();
2501         btrfs_end_io_wq_exit();
2502         unregister_filesystem(&btrfs_fs_type);
2503         btrfs_exit_sysfs();
2504         btrfs_cleanup_fs_uuids();
2505         btrfs_exit_compress();
2506 }
2507
2508 late_initcall(init_btrfs_fs);
2509 module_exit(exit_btrfs_fs)
2510
2511 MODULE_LICENSE("GPL");