fs/btrfs/super.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/module.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/fs.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/highmem.h>
  25 #include <linux/time.h>
  26 #include <linux/init.h>
  27 #include <linux/seq_file.h>
  28 #include <linux/string.h>
  29 #include <linux/backing-dev.h>
  30 #include <linux/mount.h>
  31 #include <linux/mpage.h>
  32 #include <linux/swap.h>
  33 #include <linux/writeback.h>
  34 #include <linux/statfs.h>
  35 #include <linux/compat.h>
  36 #include <linux/parser.h>
  37 #include <linux/ctype.h>
  38 #include <linux/namei.h>
  39 #include <linux/miscdevice.h>
  40 #include <linux/magic.h>
  41 #include <linux/slab.h>
  42 #include <linux/cleancache.h>
  43 #include <linux/ratelimit.h>
  44 #include <linux/btrfs.h>
  45 #include "delayed-inode.h"
  46 #include "ctree.h"
  47 #include "disk-io.h"
  48 #include "transaction.h"
  49 #include "btrfs_inode.h"
  50 #include "print-tree.h"
  51 #include "hash.h"
  52 #include "props.h"
  53 #include "xattr.h"
  54 #include "volumes.h"
  55 #include "export.h"
  56 #include "compression.h"
  57 #include "rcu-string.h"
  58 #include "dev-replace.h"
  59 #include "free-space-cache.h"
  60 #include "backref.h"
  61 #include "tests/btrfs-tests.h"
  62
  63 #include "qgroup.h"
  64 #define CREATE_TRACE_POINTS
  65 #include <trace/events/btrfs.h>
  66
  67 static const struct super_operations btrfs_super_ops;
  68
  69 /*
  70  * Types for mounting the default subvolume and a subvolume explicitly
  71  * requested by subvol=/path. That way the callchain is straightforward and we
  72  * don't have to play tricks with the mount options and recursive calls to
  73  * btrfs_mount.
  74  *
  75  * The new btrfs_root_fs_type also servers as a tag for the bdev_holder.
  76  */
  77 static struct file_system_type btrfs_fs_type;
  78 static struct file_system_type btrfs_root_fs_type;
  79
  80 static int btrfs_remount(struct super_block *sb, int *flags, char *data);
  81
  82 const char *btrfs_decode_error(int errno)
  83 {
  84         char *errstr = "unknown";
  85
  86         switch (errno) {
  87         case -EIO:
  88                 errstr = "IO failure";
  89                 break;
  90         case -ENOMEM:
  91                 errstr = "Out of memory";
  92                 break;
  93         case -EROFS:
  94                 errstr = "Readonly filesystem";
  95                 break;
  96         case -EEXIST:
  97                 errstr = "Object already exists";
  98                 break;
  99         case -ENOSPC:
 100                 errstr = "No space left";
 101                 break;
 102         case -ENOENT:
 103                 errstr = "No such entry";
 104                 break;
 105         }
 106
 107         return errstr;
 108 }
 109
 110 /*
 111  * __btrfs_handle_fs_error decodes expected errors from the caller and
 112  * invokes the approciate error response.
 113  */
 114 __cold
 115 void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function,
 116                        unsigned int line, int errno, const char *fmt, ...)
 117 {
 118         struct super_block *sb = fs_info->sb;
 119 #ifdef CONFIG_PRINTK
 120         const char *errstr;
 121 #endif
 122
 123         /*
 124          * Special case: if the error is EROFS, and we're already
 125          * under SB_RDONLY, then it is safe here.
 126          */
 127         if (errno == -EROFS && sb_rdonly(sb))
 128                 return;
 129
 130 #ifdef CONFIG_PRINTK
 131         errstr = btrfs_decode_error(errno);
 132         if (fmt) {
 133                 struct va_format vaf;
 134                 va_list args;
 135
 136                 va_start(args, fmt);
 137                 vaf.fmt = fmt;
 138                 vaf.va = &args;
 139
 140                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s (%pV)\n",
 141                         sb->s_id, function, line, errno, errstr, &vaf);
 142                 va_end(args);
 143         } else {
 144                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s\n",
 145                         sb->s_id, function, line, errno, errstr);
 146         }
 147 #endif
 148
 149         /*
 150          * Today we only save the error info to memory.  Long term we'll
 151          * also send it down to the disk
 152          */
 153         set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
 154
 155         /* Don't go through full error handling during mount */
 156         if (!(sb->s_flags & SB_BORN))
 157                 return;
 158
 159         if (sb_rdonly(sb))
 160                 return;
 161
 162         /* btrfs handle error by forcing the filesystem readonly */
 163         sb->s_flags |= SB_RDONLY;
 164         btrfs_info(fs_info, "forced readonly");
 165         /*
 166          * Note that a running device replace operation is not canceled here
 167          * although there is no way to update the progress. It would add the
 168          * risk of a deadlock, therefore the canceling is omitted. The only
 169          * penalty is that some I/O remains active until the procedure
 170          * completes. The next time when the filesystem is mounted writeable
 171          * again, the device replace operation continues.
 172          */
 173 }
 174
 175 #ifdef CONFIG_PRINTK
 176 static const char * const logtypes[] = {
 177         "emergency",
 178         "alert",
 179         "critical",
 180         "error",
 181         "warning",
 182         "notice",
 183         "info",
 184         "debug",
 185 };
 186
 187
 188 /*
 189  * Use one ratelimit state per log level so that a flood of less important
 190  * messages doesn't cause more important ones to be dropped.
 191  */
 192 static struct ratelimit_state printk_limits[] = {
 193         RATELIMIT_STATE_INIT(printk_limits[0], DEFAULT_RATELIMIT_INTERVAL, 100),
 194         RATELIMIT_STATE_INIT(printk_limits[1], DEFAULT_RATELIMIT_INTERVAL, 100),
 195         RATELIMIT_STATE_INIT(printk_limits[2], DEFAULT_RATELIMIT_INTERVAL, 100),
 196         RATELIMIT_STATE_INIT(printk_limits[3], DEFAULT_RATELIMIT_INTERVAL, 100),
 197         RATELIMIT_STATE_INIT(printk_limits[4], DEFAULT_RATELIMIT_INTERVAL, 100),
 198         RATELIMIT_STATE_INIT(printk_limits[5], DEFAULT_RATELIMIT_INTERVAL, 100),
 199         RATELIMIT_STATE_INIT(printk_limits[6], DEFAULT_RATELIMIT_INTERVAL, 100),
 200         RATELIMIT_STATE_INIT(printk_limits[7], DEFAULT_RATELIMIT_INTERVAL, 100),
 201 };
 202
 203 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 204 {
 205         char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1] = "\0";
 206         struct va_format vaf;
 207         va_list args;
 208         int kern_level;
 209         const char *type = logtypes[4];
 210         struct ratelimit_state *ratelimit = &printk_limits[4];
 211
 212         va_start(args, fmt);
 213
 214         while ((kern_level = printk_get_level(fmt)) != 0) {
 215                 size_t size = printk_skip_level(fmt) - fmt;
 216
 217                 if (kern_level >= '0' && kern_level <= '7') {
 218                         memcpy(lvl, fmt,  size);
 219                         lvl[size] = '\0';
 220                         type = logtypes[kern_level - '0'];
 221                         ratelimit = &printk_limits[kern_level - '0'];
 222                 }
 223                 fmt += size;
 224         }
 225
 226         vaf.fmt = fmt;
 227         vaf.va = &args;
 228
 229         if (__ratelimit(ratelimit))
 230                 printk("%sBTRFS %s (device %s): %pV\n", lvl, type,
 231                         fs_info ? fs_info->sb->s_id : "<unknown>", &vaf);
 232
 233         va_end(args);
 234 }
 235 #endif
 236
 237 /*
 238  * We only mark the transaction aborted and then set the file system read-only.
 239  * This will prevent new transactions from starting or trying to join this
 240  * one.
 241  *
 242  * This means that error recovery at the call site is limited to freeing
 243  * any local memory allocations and passing the error code up without
 244  * further cleanup. The transaction should complete as it normally would
 245  * in the call path but will return -EIO.
 246  *
 247  * We'll complete the cleanup in btrfs_end_transaction and
 248  * btrfs_commit_transaction.
 249  */
 250 __cold
 251 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 252                                const char *function,
 253                                unsigned int line, int errno)
 254 {
 255         struct btrfs_fs_info *fs_info = trans->fs_info;
 256
 257         trans->aborted = errno;
 258         /* Nothing used. The other threads that have joined this
 259          * transaction may be able to continue. */
 260         if (!trans->dirty && list_empty(&trans->new_bgs)) {
 261                 const char *errstr;
 262
 263                 errstr = btrfs_decode_error(errno);
 264                 btrfs_warn(fs_info,
 265                            "%s:%d: Aborting unused transaction(%s).",
 266                            function, line, errstr);
 267                 return;
 268         }
 269         WRITE_ONCE(trans->transaction->aborted, errno);
 270         /* Wake up anybody who may be waiting on this transaction */
 271         wake_up(&fs_info->transaction_wait);
 272         wake_up(&fs_info->transaction_blocked_wait);
 273         __btrfs_handle_fs_error(fs_info, function, line, errno, NULL);
 274 }
 275 /*
 276  * __btrfs_panic decodes unexpected, fatal errors from the caller,
 277  * issues an alert, and either panics or BUGs, depending on mount options.
 278  */
 279 __cold
 280 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 281                    unsigned int line, int errno, const char *fmt, ...)
 282 {
 283         char *s_id = "<unknown>";
 284         const char *errstr;
 285         struct va_format vaf = { .fmt = fmt };
 286         va_list args;
 287
 288         if (fs_info)
 289                 s_id = fs_info->sb->s_id;
 290
 291         va_start(args, fmt);
 292         vaf.va = &args;
 293
 294         errstr = btrfs_decode_error(errno);
 295         if (fs_info && (btrfs_test_opt(fs_info, PANIC_ON_FATAL_ERROR)))
 296                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
 297                         s_id, function, line, &vaf, errno, errstr);
 298
 299         btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
 300                    function, line, &vaf, errno, errstr);
 301         va_end(args);
 302         /* Caller calls BUG() */
 303 }
 304
 305 static void btrfs_put_super(struct super_block *sb)
 306 {
 307         close_ctree(btrfs_sb(sb));
 308 }
 309
 310 enum {
 311         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 312         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 313         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 314         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 315         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 316         Opt_space_cache, Opt_space_cache_version, Opt_clear_cache,
 317         Opt_user_subvol_rm_allowed, Opt_enospc_debug, Opt_subvolrootid,
 318         Opt_defrag, Opt_inode_cache, Opt_no_space_cache, Opt_recovery,
 319         Opt_skip_balance, Opt_check_integrity,
 320         Opt_check_integrity_including_extent_data,
 321         Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
 322         Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
 323         Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
 324         Opt_datasum, Opt_treelog, Opt_noinode_cache, Opt_usebackuproot,
 325         Opt_nologreplay, Opt_norecovery,
 326 #ifdef CONFIG_BTRFS_DEBUG
 327         Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 328 #endif
 329 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 330         Opt_ref_verify,
 331 #endif
 332         Opt_err,
 333 };
 334
 335 static const match_table_t tokens = {
 336         {Opt_degraded, "degraded"},
 337         {Opt_subvol, "subvol=%s"},
 338         {Opt_subvolid, "subvolid=%s"},
 339         {Opt_device, "device=%s"},
 340         {Opt_nodatasum, "nodatasum"},
 341         {Opt_datasum, "datasum"},
 342         {Opt_nodatacow, "nodatacow"},
 343         {Opt_datacow, "datacow"},
 344         {Opt_nobarrier, "nobarrier"},
 345         {Opt_barrier, "barrier"},
 346         {Opt_max_inline, "max_inline=%s"},
 347         {Opt_alloc_start, "alloc_start=%s"},
 348         {Opt_thread_pool, "thread_pool=%u"},
 349         {Opt_compress, "compress"},
 350         {Opt_compress_type, "compress=%s"},
 351         {Opt_compress_force, "compress-force"},
 352         {Opt_compress_force_type, "compress-force=%s"},
 353         {Opt_ssd, "ssd"},
 354         {Opt_ssd_spread, "ssd_spread"},
 355         {Opt_nossd, "nossd"},
 356         {Opt_acl, "acl"},
 357         {Opt_noacl, "noacl"},
 358         {Opt_notreelog, "notreelog"},
 359         {Opt_treelog, "treelog"},
 360         {Opt_nologreplay, "nologreplay"},
 361         {Opt_norecovery, "norecovery"},
 362         {Opt_flushoncommit, "flushoncommit"},
 363         {Opt_noflushoncommit, "noflushoncommit"},
 364         {Opt_ratio, "metadata_ratio=%u"},
 365         {Opt_discard, "discard"},
 366         {Opt_nodiscard, "nodiscard"},
 367         {Opt_space_cache, "space_cache"},
 368         {Opt_space_cache_version, "space_cache=%s"},
 369         {Opt_clear_cache, "clear_cache"},
 370         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 371         {Opt_enospc_debug, "enospc_debug"},
 372         {Opt_noenospc_debug, "noenospc_debug"},
 373         {Opt_subvolrootid, "subvolrootid=%d"},
 374         {Opt_defrag, "autodefrag"},
 375         {Opt_nodefrag, "noautodefrag"},
 376         {Opt_inode_cache, "inode_cache"},
 377         {Opt_noinode_cache, "noinode_cache"},
 378         {Opt_no_space_cache, "nospace_cache"},
 379         {Opt_recovery, "recovery"}, /* deprecated */
 380         {Opt_usebackuproot, "usebackuproot"},
 381         {Opt_skip_balance, "skip_balance"},
 382         {Opt_check_integrity, "check_int"},
 383         {Opt_check_integrity_including_extent_data, "check_int_data"},
 384         {Opt_check_integrity_print_mask, "check_int_print_mask=%u"},
 385         {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
 386         {Opt_fatal_errors, "fatal_errors=%s"},
 387         {Opt_commit_interval, "commit=%d"},
 388 #ifdef CONFIG_BTRFS_DEBUG
 389         {Opt_fragment_data, "fragment=data"},
 390         {Opt_fragment_metadata, "fragment=metadata"},
 391         {Opt_fragment_all, "fragment=all"},
 392 #endif
 393 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 394         {Opt_ref_verify, "ref_verify"},
 395 #endif
 396         {Opt_err, NULL},
 397 };
 398
 399 /*
 400  * Regular mount options parser.  Everything that is needed only when
 401  * reading in a new superblock is parsed here.
 402  * XXX JDM: This needs to be cleaned up for remount.
 403  */
 404 int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 405                         unsigned long new_flags)
 406 {
 407         substring_t args[MAX_OPT_ARGS];
 408         char *p, *num;
 409         u64 cache_gen;
 410         int intarg;
 411         int ret = 0;
 412         char *compress_type;
 413         bool compress_force = false;
 414         enum btrfs_compression_type saved_compress_type;
 415         bool saved_compress_force;
 416         int no_compress = 0;
 417
 418         cache_gen = btrfs_super_cache_generation(info->super_copy);
 419         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
 420                 btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
 421         else if (cache_gen)
 422                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 423
 424         /*
 425          * Even the options are empty, we still need to do extra check
 426          * against new flags
 427          */
 428         if (!options)
 429                 goto check;
 430
 431         while ((p = strsep(&options, ",")) != NULL) {
 432                 int token;
 433                 if (!*p)
 434                         continue;
 435
 436                 token = match_token(p, tokens, args);
 437                 switch (token) {
 438                 case Opt_degraded:
 439                         btrfs_info(info, "allowing degraded mounts");
 440                         btrfs_set_opt(info->mount_opt, DEGRADED);
 441                         break;
 442                 case Opt_subvol:
 443                 case Opt_subvolid:
 444                 case Opt_subvolrootid:
 445                 case Opt_device:
 446                         /*
 447                          * These are parsed by btrfs_parse_subvol_options
 448                          * and btrfs_parse_early_options
 449                          * and can be happily ignored here.
 450                          */
 451                         break;
 452                 case Opt_nodatasum:
 453                         btrfs_set_and_info(info, NODATASUM,
 454                                            "setting nodatasum");
 455                         break;
 456                 case Opt_datasum:
 457                         if (btrfs_test_opt(info, NODATASUM)) {
 458                                 if (btrfs_test_opt(info, NODATACOW))
 459                                         btrfs_info(info,
 460                                                    "setting datasum, datacow enabled");
 461                                 else
 462                                         btrfs_info(info, "setting datasum");
 463                         }
 464                         btrfs_clear_opt(info->mount_opt, NODATACOW);
 465                         btrfs_clear_opt(info->mount_opt, NODATASUM);
 466                         break;
 467                 case Opt_nodatacow:
 468                         if (!btrfs_test_opt(info, NODATACOW)) {
 469                                 if (!btrfs_test_opt(info, COMPRESS) ||
 470                                     !btrfs_test_opt(info, FORCE_COMPRESS)) {
 471                                         btrfs_info(info,
 472                                                    "setting nodatacow, compression disabled");
 473                                 } else {
 474                                         btrfs_info(info, "setting nodatacow");
 475                                 }
 476                         }
 477                         btrfs_clear_opt(info->mount_opt, COMPRESS);
 478                         btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 479                         btrfs_set_opt(info->mount_opt, NODATACOW);
 480                         btrfs_set_opt(info->mount_opt, NODATASUM);
 481                         break;
 482                 case Opt_datacow:
 483                         btrfs_clear_and_info(info, NODATACOW,
 484                                              "setting datacow");
 485                         break;
 486                 case Opt_compress_force:
 487                 case Opt_compress_force_type:
 488                         compress_force = true;
 489                         /* Fallthrough */
 490                 case Opt_compress:
 491                 case Opt_compress_type:
 492                         saved_compress_type = btrfs_test_opt(info,
 493                                                              COMPRESS) ?
 494                                 info->compress_type : BTRFS_COMPRESS_NONE;
 495                         saved_compress_force =
 496                                 btrfs_test_opt(info, FORCE_COMPRESS);
 497                         if (token == Opt_compress ||
 498                             token == Opt_compress_force ||
 499                             strncmp(args[0].from, "zlib", 4) == 0) {
 500                                 compress_type = "zlib";
 501
 502                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 503                                 info->compress_level = BTRFS_ZLIB_DEFAULT_LEVEL;
 504                                 /*
 505                                  * args[0] contains uninitialized data since
 506                                  * for these tokens we don't expect any
 507                                  * parameter.
 508                                  */
 509                                 if (token != Opt_compress &&
 510                                     token != Opt_compress_force)
 511                                         info->compress_level =
 512                                           btrfs_compress_str2level(args[0].from);
 513                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 514                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 515                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 516                                 no_compress = 0;
 517                         } else if (strncmp(args[0].from, "lzo", 3) == 0) {
 518                                 compress_type = "lzo";
 519                                 info->compress_type = BTRFS_COMPRESS_LZO;
 520                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 521                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 522                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 523                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
 524                                 no_compress = 0;
 525                         } else if (strcmp(args[0].from, "zstd") == 0) {
 526                                 compress_type = "zstd";
 527                                 info->compress_type = BTRFS_COMPRESS_ZSTD;
 528                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 529                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 530                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 531                                 btrfs_set_fs_incompat(info, COMPRESS_ZSTD);
 532                                 no_compress = 0;
 533                         } else if (strncmp(args[0].from, "no", 2) == 0) {
 534                                 compress_type = "no";
 535                                 btrfs_clear_opt(info->mount_opt, COMPRESS);
 536                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 537                                 compress_force = false;
 538                                 no_compress++;
 539                         } else {
 540                                 ret = -EINVAL;
 541                                 goto out;
 542                         }
 543
 544                         if (compress_force) {
 545                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 546                         } else {
 547                                 /*
 548                                  * If we remount from compress-force=xxx to
 549                                  * compress=xxx, we need clear FORCE_COMPRESS
 550                                  * flag, otherwise, there is no way for users
 551                                  * to disable forcible compression separately.
 552                                  */
 553                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 554                         }
 555                         if ((btrfs_test_opt(info, COMPRESS) &&
 556                              (info->compress_type != saved_compress_type ||
 557                               compress_force != saved_compress_force)) ||
 558                             (!btrfs_test_opt(info, COMPRESS) &&
 559                              no_compress == 1)) {
 560                                 btrfs_info(info, "%s %s compression, level %d",
 561                                            (compress_force) ? "force" : "use",
 562                                            compress_type, info->compress_level);
 563                         }
 564                         compress_force = false;
 565                         break;
 566                 case Opt_ssd:
 567                         btrfs_set_and_info(info, SSD,
 568                                            "enabling ssd optimizations");
 569                         btrfs_clear_opt(info->mount_opt, NOSSD);
 570                         break;
 571                 case Opt_ssd_spread:
 572                         btrfs_set_and_info(info, SSD,
 573                                            "enabling ssd optimizations");
 574                         btrfs_set_and_info(info, SSD_SPREAD,
 575                                            "using spread ssd allocation scheme");
 576                         btrfs_clear_opt(info->mount_opt, NOSSD);
 577                         break;
 578                 case Opt_nossd:
 579                         btrfs_set_opt(info->mount_opt, NOSSD);
 580                         btrfs_clear_and_info(info, SSD,
 581                                              "not using ssd optimizations");
 582                         btrfs_clear_and_info(info, SSD_SPREAD,
 583                                              "not using spread ssd allocation scheme");
 584                         break;
 585                 case Opt_barrier:
 586                         btrfs_clear_and_info(info, NOBARRIER,
 587                                              "turning on barriers");
 588                         break;
 589                 case Opt_nobarrier:
 590                         btrfs_set_and_info(info, NOBARRIER,
 591                                            "turning off barriers");
 592                         break;
 593                 case Opt_thread_pool:
 594                         ret = match_int(&args[0], &intarg);
 595                         if (ret) {
 596                                 goto out;
 597                         } else if (intarg == 0) {
 598                                 ret = -EINVAL;
 599                                 goto out;
 600                         }
 601                         info->thread_pool_size = intarg;
 602                         break;
 603                 case Opt_max_inline:
 604                         num = match_strdup(&args[0]);
 605                         if (num) {
 606                                 info->max_inline = memparse(num, NULL);
 607                                 kfree(num);
 608
 609                                 if (info->max_inline) {
 610                                         info->max_inline = min_t(u64,
 611                                                 info->max_inline,
 612                                                 info->sectorsize);
 613                                 }
 614                                 btrfs_info(info, "max_inline at %llu",
 615                                            info->max_inline);
 616                         } else {
 617                                 ret = -ENOMEM;
 618                                 goto out;
 619                         }
 620                         break;
 621                 case Opt_alloc_start:
 622                         btrfs_info(info,
 623                                 "option alloc_start is obsolete, ignored");
 624                         break;
 625                 case Opt_acl:
 626 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 627                         info->sb->s_flags |= SB_POSIXACL;
 628                         break;
 629 #else
 630                         btrfs_err(info, "support for ACL not compiled in!");
 631                         ret = -EINVAL;
 632                         goto out;
 633 #endif
 634                 case Opt_noacl:
 635                         info->sb->s_flags &= ~SB_POSIXACL;
 636                         break;
 637                 case Opt_notreelog:
 638                         btrfs_set_and_info(info, NOTREELOG,
 639                                            "disabling tree log");
 640                         break;
 641                 case Opt_treelog:
 642                         btrfs_clear_and_info(info, NOTREELOG,
 643                                              "enabling tree log");
 644                         break;
 645                 case Opt_norecovery:
 646                 case Opt_nologreplay:
 647                         btrfs_set_and_info(info, NOLOGREPLAY,
 648                                            "disabling log replay at mount time");
 649                         break;
 650                 case Opt_flushoncommit:
 651                         btrfs_set_and_info(info, FLUSHONCOMMIT,
 652                                            "turning on flush-on-commit");
 653                         break;
 654                 case Opt_noflushoncommit:
 655                         btrfs_clear_and_info(info, FLUSHONCOMMIT,
 656                                              "turning off flush-on-commit");
 657                         break;
 658                 case Opt_ratio:
 659                         ret = match_int(&args[0], &intarg);
 660                         if (ret)
 661                                 goto out;
 662                         info->metadata_ratio = intarg;
 663                         btrfs_info(info, "metadata ratio %u",
 664                                    info->metadata_ratio);
 665                         break;
 666                 case Opt_discard:
 667                         btrfs_set_and_info(info, DISCARD,
 668                                            "turning on discard");
 669                         break;
 670                 case Opt_nodiscard:
 671                         btrfs_clear_and_info(info, DISCARD,
 672                                              "turning off discard");
 673                         break;
 674                 case Opt_space_cache:
 675                 case Opt_space_cache_version:
 676                         if (token == Opt_space_cache ||
 677                             strcmp(args[0].from, "v1") == 0) {
 678                                 btrfs_clear_opt(info->mount_opt,
 679                                                 FREE_SPACE_TREE);
 680                                 btrfs_set_and_info(info, SPACE_CACHE,
 681                                            "enabling disk space caching");
 682                         } else if (strcmp(args[0].from, "v2") == 0) {
 683                                 btrfs_clear_opt(info->mount_opt,
 684                                                 SPACE_CACHE);
 685                                 btrfs_set_and_info(info, FREE_SPACE_TREE,
 686                                                    "enabling free space tree");
 687                         } else {
 688                                 ret = -EINVAL;
 689                                 goto out;
 690                         }
 691                         break;
 692                 case Opt_rescan_uuid_tree:
 693                         btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
 694                         break;
 695                 case Opt_no_space_cache:
 696                         if (btrfs_test_opt(info, SPACE_CACHE)) {
 697                                 btrfs_clear_and_info(info, SPACE_CACHE,
 698                                              "disabling disk space caching");
 699                         }
 700                         if (btrfs_test_opt(info, FREE_SPACE_TREE)) {
 701                                 btrfs_clear_and_info(info, FREE_SPACE_TREE,
 702                                              "disabling free space tree");
 703                         }
 704                         break;
 705                 case Opt_inode_cache:
 706                         btrfs_set_pending_and_info(info, INODE_MAP_CACHE,
 707                                            "enabling inode map caching");
 708                         break;
 709                 case Opt_noinode_cache:
 710                         btrfs_clear_pending_and_info(info, INODE_MAP_CACHE,
 711                                              "disabling inode map caching");
 712                         break;
 713                 case Opt_clear_cache:
 714                         btrfs_set_and_info(info, CLEAR_CACHE,
 715                                            "force clearing of disk cache");
 716                         break;
 717                 case Opt_user_subvol_rm_allowed:
 718                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 719                         break;
 720                 case Opt_enospc_debug:
 721                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 722                         break;
 723                 case Opt_noenospc_debug:
 724                         btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
 725                         break;
 726                 case Opt_defrag:
 727                         btrfs_set_and_info(info, AUTO_DEFRAG,
 728                                            "enabling auto defrag");
 729                         break;
 730                 case Opt_nodefrag:
 731                         btrfs_clear_and_info(info, AUTO_DEFRAG,
 732                                              "disabling auto defrag");
 733                         break;
 734                 case Opt_recovery:
 735                         btrfs_warn(info,
 736                                    "'recovery' is deprecated, use 'usebackuproot' instead");
 737                 case Opt_usebackuproot:
 738                         btrfs_info(info,
 739                                    "trying to use backup root at mount time");
 740                         btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
 741                         break;
 742                 case Opt_skip_balance:
 743                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 744                         break;
 745 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 746                 case Opt_check_integrity_including_extent_data:
 747                         btrfs_info(info,
 748                                    "enabling check integrity including extent data");
 749                         btrfs_set_opt(info->mount_opt,
 750                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 751                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 752                         break;
 753                 case Opt_check_integrity:
 754                         btrfs_info(info, "enabling check integrity");
 755                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 756                         break;
 757                 case Opt_check_integrity_print_mask:
 758                         ret = match_int(&args[0], &intarg);
 759                         if (ret)
 760                                 goto out;
 761                         info->check_integrity_print_mask = intarg;
 762                         btrfs_info(info, "check_integrity_print_mask 0x%x",
 763                                    info->check_integrity_print_mask);
 764                         break;
 765 #else
 766                 case Opt_check_integrity_including_extent_data:
 767                 case Opt_check_integrity:
 768                 case Opt_check_integrity_print_mask:
 769                         btrfs_err(info,
 770                                   "support for check_integrity* not compiled in!");
 771                         ret = -EINVAL;
 772                         goto out;
 773 #endif
 774                 case Opt_fatal_errors:
 775                         if (strcmp(args[0].from, "panic") == 0)
 776                                 btrfs_set_opt(info->mount_opt,
 777                                               PANIC_ON_FATAL_ERROR);
 778                         else if (strcmp(args[0].from, "bug") == 0)
 779                                 btrfs_clear_opt(info->mount_opt,
 780                                               PANIC_ON_FATAL_ERROR);
 781                         else {
 782                                 ret = -EINVAL;
 783                                 goto out;
 784                         }
 785                         break;
 786                 case Opt_commit_interval:
 787                         intarg = 0;
 788                         ret = match_int(&args[0], &intarg);
 789                         if (ret < 0) {
 790                                 btrfs_err(info, "invalid commit interval");
 791                                 ret = -EINVAL;
 792                                 goto out;
 793                         }
 794                         if (intarg > 0) {
 795                                 if (intarg > 300) {
 796                                         btrfs_warn(info,
 797                                                 "excessive commit interval %d",
 798                                                 intarg);
 799                                 }
 800                                 info->commit_interval = intarg;
 801                         } else {
 802                                 btrfs_info(info,
 803                                            "using default commit interval %ds",
 804                                            BTRFS_DEFAULT_COMMIT_INTERVAL);
 805                                 info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
 806                         }
 807                         break;
 808 #ifdef CONFIG_BTRFS_DEBUG
 809                 case Opt_fragment_all:
 810                         btrfs_info(info, "fragmenting all space");
 811                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 812                         btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
 813                         break;
 814                 case Opt_fragment_metadata:
 815                         btrfs_info(info, "fragmenting metadata");
 816                         btrfs_set_opt(info->mount_opt,
 817                                       FRAGMENT_METADATA);
 818                         break;
 819                 case Opt_fragment_data:
 820                         btrfs_info(info, "fragmenting data");
 821                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 822                         break;
 823 #endif
 824 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 825                 case Opt_ref_verify:
 826                         btrfs_info(info, "doing ref verification");
 827                         btrfs_set_opt(info->mount_opt, REF_VERIFY);
 828                         break;
 829 #endif
 830                 case Opt_err:
 831                         btrfs_info(info, "unrecognized mount option '%s'", p);
 832                         ret = -EINVAL;
 833                         goto out;
 834                 default:
 835                         break;
 836                 }
 837         }
 838 check:
 839         /*
 840          * Extra check for current option against current flag
 841          */
 842         if (btrfs_test_opt(info, NOLOGREPLAY) && !(new_flags & SB_RDONLY)) {
 843                 btrfs_err(info,
 844                           "nologreplay must be used with ro mount option");
 845                 ret = -EINVAL;
 846         }
 847 out:
 848         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) &&
 849             !btrfs_test_opt(info, FREE_SPACE_TREE) &&
 850             !btrfs_test_opt(info, CLEAR_CACHE)) {
 851                 btrfs_err(info, "cannot disable free space tree");
 852                 ret = -EINVAL;
 853
 854         }
 855         if (!ret && btrfs_test_opt(info, SPACE_CACHE))
 856                 btrfs_info(info, "disk space caching is enabled");
 857         if (!ret && btrfs_test_opt(info, FREE_SPACE_TREE))
 858                 btrfs_info(info, "using free space tree");
 859         return ret;
 860 }
 861
 862 /*
 863  * Parse mount options that are required early in the mount process.
 864  *
 865  * All other options will be parsed on much later in the mount process and
 866  * only when we need to allocate a new super block.
 867  */
 868 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 869                 void *holder, struct btrfs_fs_devices **fs_devices)
 870 {
 871         substring_t args[MAX_OPT_ARGS];
 872         char *device_name, *opts, *orig, *p;
 873         int error = 0;
 874
 875         if (!options)
 876                 return 0;
 877
 878         /*
 879          * strsep changes the string, duplicate it because btrfs_parse_options
 880          * gets called later
 881          */
 882         opts = kstrdup(options, GFP_KERNEL);
 883         if (!opts)
 884                 return -ENOMEM;
 885         orig = opts;
 886
 887         while ((p = strsep(&opts, ",")) != NULL) {
 888                 int token;
 889
 890                 if (!*p)
 891                         continue;
 892
 893                 token = match_token(p, tokens, args);
 894                 if (token == Opt_device) {
 895                         device_name = match_strdup(&args[0]);
 896                         if (!device_name) {
 897                                 error = -ENOMEM;
 898                                 goto out;
 899                         }
 900                         error = btrfs_scan_one_device(device_name,
 901                                         flags, holder, fs_devices);
 902                         kfree(device_name);
 903                         if (error)
 904                                 goto out;
 905                 }
 906         }
 907
 908 out:
 909         kfree(orig);
 910         return error;
 911 }
 912
 913 /*
 914  * Parse mount options that are related to subvolume id
 915  *
 916  * The value is later passed to mount_subvol()
 917  */
 918 static int btrfs_parse_subvol_options(const char *options, fmode_t flags,
 919                 char **subvol_name, u64 *subvol_objectid)
 920 {
 921         substring_t args[MAX_OPT_ARGS];
 922         char *opts, *orig, *p;
 923         char *num = NULL;
 924         int error = 0;
 925
 926         if (!options)
 927                 return 0;
 928
 929         /*
 930          * strsep changes the string, duplicate it because
 931          * btrfs_parse_early_options gets called later
 932          */
 933         opts = kstrdup(options, GFP_KERNEL);
 934         if (!opts)
 935                 return -ENOMEM;
 936         orig = opts;
 937
 938         while ((p = strsep(&opts, ",")) != NULL) {
 939                 int token;
 940                 if (!*p)
 941                         continue;
 942
 943                 token = match_token(p, tokens, args);
 944                 switch (token) {
 945                 case Opt_subvol:
 946                         kfree(*subvol_name);
 947                         *subvol_name = match_strdup(&args[0]);
 948                         if (!*subvol_name) {
 949                                 error = -ENOMEM;
 950                                 goto out;
 951                         }
 952                         break;
 953                 case Opt_subvolid:
 954                         num = match_strdup(&args[0]);
 955                         if (num) {
 956                                 *subvol_objectid = memparse(num, NULL);
 957                                 kfree(num);
 958                                 /* we want the original fs_tree */
 959                                 if (!*subvol_objectid)
 960                                         *subvol_objectid =
 961                                                 BTRFS_FS_TREE_OBJECTID;
 962                         } else {
 963                                 error = -EINVAL;
 964                                 goto out;
 965                         }
 966                         break;
 967                 case Opt_subvolrootid:
 968                         pr_warn("BTRFS: 'subvolrootid' mount option is deprecated and has no effect\n");
 969                         break;
 970                 default:
 971                         break;
 972                 }
 973         }
 974
 975 out:
 976         kfree(orig);
 977         return error;
 978 }
 979
 980 static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 981                                            u64 subvol_objectid)
 982 {
 983         struct btrfs_root *root = fs_info->tree_root;
 984         struct btrfs_root *fs_root;
 985         struct btrfs_root_ref *root_ref;
 986         struct btrfs_inode_ref *inode_ref;
 987         struct btrfs_key key;
 988         struct btrfs_path *path = NULL;
 989         char *name = NULL, *ptr;
 990         u64 dirid;
 991         int len;
 992         int ret;
 993
 994         path = btrfs_alloc_path();
 995         if (!path) {
 996                 ret = -ENOMEM;
 997                 goto err;
 998         }
 999         path->leave_spinning = 1;
1000
1001         name = kmalloc(PATH_MAX, GFP_KERNEL);
1002         if (!name) {
1003                 ret = -ENOMEM;
1004                 goto err;
1005         }
1006         ptr = name + PATH_MAX - 1;
1007         ptr[0] = '\0';
1008
1009         /*
1010          * Walk up the subvolume trees in the tree of tree roots by root
1011          * backrefs until we hit the top-level subvolume.
1012          */
1013         while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
1014                 key.objectid = subvol_objectid;
1015                 key.type = BTRFS_ROOT_BACKREF_KEY;
1016                 key.offset = (u64)-1;
1017
1018                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1019                 if (ret < 0) {
1020                         goto err;
1021                 } else if (ret > 0) {
1022                         ret = btrfs_previous_item(root, path, subvol_objectid,
1023                                                   BTRFS_ROOT_BACKREF_KEY);
1024                         if (ret < 0) {
1025                                 goto err;
1026                         } else if (ret > 0) {
1027                                 ret = -ENOENT;
1028                                 goto err;
1029                         }
1030                 }
1031
1032                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1033                 subvol_objectid = key.offset;
1034
1035                 root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1036                                           struct btrfs_root_ref);
1037                 len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
1038                 ptr -= len + 1;
1039                 if (ptr < name) {
1040                         ret = -ENAMETOOLONG;
1041                         goto err;
1042                 }
1043                 read_extent_buffer(path->nodes[0], ptr + 1,
1044                                    (unsigned long)(root_ref + 1), len);
1045                 ptr[0] = '/';
1046                 dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
1047                 btrfs_release_path(path);
1048
1049                 key.objectid = subvol_objectid;
1050                 key.type = BTRFS_ROOT_ITEM_KEY;
1051                 key.offset = (u64)-1;
1052                 fs_root = btrfs_read_fs_root_no_name(fs_info, &key);
1053                 if (IS_ERR(fs_root)) {
1054                         ret = PTR_ERR(fs_root);
1055                         goto err;
1056                 }
1057
1058                 /*
1059                  * Walk up the filesystem tree by inode refs until we hit the
1060                  * root directory.
1061                  */
1062                 while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
1063                         key.objectid = dirid;
1064                         key.type = BTRFS_INODE_REF_KEY;
1065                         key.offset = (u64)-1;
1066
1067                         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1068                         if (ret < 0) {
1069                                 goto err;
1070                         } else if (ret > 0) {
1071                                 ret = btrfs_previous_item(fs_root, path, dirid,
1072                                                           BTRFS_INODE_REF_KEY);
1073                                 if (ret < 0) {
1074                                         goto err;
1075                                 } else if (ret > 0) {
1076                                         ret = -ENOENT;
1077                                         goto err;
1078                                 }
1079                         }
1080
1081                         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1082                         dirid = key.offset;
1083
1084                         inode_ref = btrfs_item_ptr(path->nodes[0],
1085                                                    path->slots[0],
1086                                                    struct btrfs_inode_ref);
1087                         len = btrfs_inode_ref_name_len(path->nodes[0],
1088                                                        inode_ref);
1089                         ptr -= len + 1;
1090                         if (ptr < name) {
1091                                 ret = -ENAMETOOLONG;
1092                                 goto err;
1093                         }
1094                         read_extent_buffer(path->nodes[0], ptr + 1,
1095                                            (unsigned long)(inode_ref + 1), len);
1096                         ptr[0] = '/';
1097                         btrfs_release_path(path);
1098                 }
1099         }
1100
1101         btrfs_free_path(path);
1102         if (ptr == name + PATH_MAX - 1) {
1103                 name[0] = '/';
1104                 name[1] = '\0';
1105         } else {
1106                 memmove(name, ptr, name + PATH_MAX - ptr);
1107         }
1108         return name;
1109
1110 err:
1111         btrfs_free_path(path);
1112         kfree(name);
1113         return ERR_PTR(ret);
1114 }
1115
1116 static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
1117 {
1118         struct btrfs_root *root = fs_info->tree_root;
1119         struct btrfs_dir_item *di;
1120         struct btrfs_path *path;
1121         struct btrfs_key location;
1122         u64 dir_id;
1123
1124         path = btrfs_alloc_path();
1125         if (!path)
1126                 return -ENOMEM;
1127         path->leave_spinning = 1;
1128
1129         /*
1130          * Find the "default" dir item which points to the root item that we
1131          * will mount by default if we haven't been given a specific subvolume
1132          * to mount.
1133          */
1134         dir_id = btrfs_super_root_dir(fs_info->super_copy);
1135         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
1136         if (IS_ERR(di)) {
1137                 btrfs_free_path(path);
1138                 return PTR_ERR(di);
1139         }
1140         if (!di) {
1141                 /*
1142                  * Ok the default dir item isn't there.  This is weird since
1143                  * it's always been there, but don't freak out, just try and
1144                  * mount the top-level subvolume.
1145                  */
1146                 btrfs_free_path(path);
1147                 *objectid = BTRFS_FS_TREE_OBJECTID;
1148                 return 0;
1149         }
1150
1151         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
1152         btrfs_free_path(path);
1153         *objectid = location.objectid;
1154         return 0;
1155 }
1156
1157 static int btrfs_fill_super(struct super_block *sb,
1158                             struct btrfs_fs_devices *fs_devices,
1159                             void *data)
1160 {
1161         struct inode *inode;
1162         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1163         struct btrfs_key key;
1164         int err;
1165
1166         sb->s_maxbytes = MAX_LFS_FILESIZE;
1167         sb->s_magic = BTRFS_SUPER_MAGIC;
1168         sb->s_op = &btrfs_super_ops;
1169         sb->s_d_op = &btrfs_dentry_operations;
1170         sb->s_export_op = &btrfs_export_ops;
1171         sb->s_xattr = btrfs_xattr_handlers;
1172         sb->s_time_gran = 1;
1173 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
1174         sb->s_flags |= SB_POSIXACL;
1175 #endif
1176         sb->s_flags |= SB_I_VERSION;
1177         sb->s_iflags |= SB_I_CGROUPWB;
1178
1179         err = super_setup_bdi(sb);
1180         if (err) {
1181                 btrfs_err(fs_info, "super_setup_bdi failed");
1182                 return err;
1183         }
1184
1185         err = open_ctree(sb, fs_devices, (char *)data);
1186         if (err) {
1187                 btrfs_err(fs_info, "open_ctree failed");
1188                 return err;
1189         }
1190
1191         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
1192         key.type = BTRFS_INODE_ITEM_KEY;
1193         key.offset = 0;
1194         inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
1195         if (IS_ERR(inode)) {
1196                 err = PTR_ERR(inode);
1197                 goto fail_close;
1198         }
1199
1200         sb->s_root = d_make_root(inode);
1201         if (!sb->s_root) {
1202                 err = -ENOMEM;
1203                 goto fail_close;
1204         }
1205
1206         cleancache_init_fs(sb);
1207         sb->s_flags |= SB_ACTIVE;
1208         return 0;
1209
1210 fail_close:
1211         close_ctree(fs_info);
1212         return err;
1213 }
1214
1215 int btrfs_sync_fs(struct super_block *sb, int wait)
1216 {
1217         struct btrfs_trans_handle *trans;
1218         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1219         struct btrfs_root *root = fs_info->tree_root;
1220
1221         trace_btrfs_sync_fs(fs_info, wait);
1222
1223         if (!wait) {
1224                 filemap_flush(fs_info->btree_inode->i_mapping);
1225                 return 0;
1226         }
1227
1228         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
1229
1230         trans = btrfs_attach_transaction_barrier(root);
1231         if (IS_ERR(trans)) {
1232                 /* no transaction, don't bother */
1233                 if (PTR_ERR(trans) == -ENOENT) {
1234                         /*
1235                          * Exit unless we have some pending changes
1236                          * that need to go through commit
1237                          */
1238                         if (fs_info->pending_changes == 0)
1239                                 return 0;
1240                         /*
1241                          * A non-blocking test if the fs is frozen. We must not
1242                          * start a new transaction here otherwise a deadlock
1243                          * happens. The pending operations are delayed to the
1244                          * next commit after thawing.
1245                          */
1246                         if (sb_start_write_trylock(sb))
1247                                 sb_end_write(sb);
1248                         else
1249                                 return 0;
1250                         trans = btrfs_start_transaction(root, 0);
1251                 }
1252                 if (IS_ERR(trans))
1253                         return PTR_ERR(trans);
1254         }
1255         return btrfs_commit_transaction(trans);
1256 }
1257
1258 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1259 {
1260         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1261         const char *compress_type;
1262
1263         if (btrfs_test_opt(info, DEGRADED))
1264                 seq_puts(seq, ",degraded");
1265         if (btrfs_test_opt(info, NODATASUM))
1266                 seq_puts(seq, ",nodatasum");
1267         if (btrfs_test_opt(info, NODATACOW))
1268                 seq_puts(seq, ",nodatacow");
1269         if (btrfs_test_opt(info, NOBARRIER))
1270                 seq_puts(seq, ",nobarrier");
1271         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1272                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
1273         if (info->thread_pool_size !=  min_t(unsigned long,
1274                                              num_online_cpus() + 2, 8))
1275                 seq_printf(seq, ",thread_pool=%u", info->thread_pool_size);
1276         if (btrfs_test_opt(info, COMPRESS)) {
1277                 compress_type = btrfs_compress_type2str(info->compress_type);
1278                 if (btrfs_test_opt(info, FORCE_COMPRESS))
1279                         seq_printf(seq, ",compress-force=%s", compress_type);
1280                 else
1281                         seq_printf(seq, ",compress=%s", compress_type);
1282                 if (info->compress_level)
1283                         seq_printf(seq, ":%d", info->compress_level);
1284         }
1285         if (btrfs_test_opt(info, NOSSD))
1286                 seq_puts(seq, ",nossd");
1287         if (btrfs_test_opt(info, SSD_SPREAD))
1288                 seq_puts(seq, ",ssd_spread");
1289         else if (btrfs_test_opt(info, SSD))
1290                 seq_puts(seq, ",ssd");
1291         if (btrfs_test_opt(info, NOTREELOG))
1292                 seq_puts(seq, ",notreelog");
1293         if (btrfs_test_opt(info, NOLOGREPLAY))
1294                 seq_puts(seq, ",nologreplay");
1295         if (btrfs_test_opt(info, FLUSHONCOMMIT))
1296                 seq_puts(seq, ",flushoncommit");
1297         if (btrfs_test_opt(info, DISCARD))
1298                 seq_puts(seq, ",discard");
1299         if (!(info->sb->s_flags & SB_POSIXACL))
1300                 seq_puts(seq, ",noacl");
1301         if (btrfs_test_opt(info, SPACE_CACHE))
1302                 seq_puts(seq, ",space_cache");
1303         else if (btrfs_test_opt(info, FREE_SPACE_TREE))
1304                 seq_puts(seq, ",space_cache=v2");
1305         else
1306                 seq_puts(seq, ",nospace_cache");
1307         if (btrfs_test_opt(info, RESCAN_UUID_TREE))
1308                 seq_puts(seq, ",rescan_uuid_tree");
1309         if (btrfs_test_opt(info, CLEAR_CACHE))
1310                 seq_puts(seq, ",clear_cache");
1311         if (btrfs_test_opt(info, USER_SUBVOL_RM_ALLOWED))
1312                 seq_puts(seq, ",user_subvol_rm_allowed");
1313         if (btrfs_test_opt(info, ENOSPC_DEBUG))
1314                 seq_puts(seq, ",enospc_debug");
1315         if (btrfs_test_opt(info, AUTO_DEFRAG))
1316                 seq_puts(seq, ",autodefrag");
1317         if (btrfs_test_opt(info, INODE_MAP_CACHE))
1318                 seq_puts(seq, ",inode_cache");
1319         if (btrfs_test_opt(info, SKIP_BALANCE))
1320                 seq_puts(seq, ",skip_balance");
1321 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1322         if (btrfs_test_opt(info, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
1323                 seq_puts(seq, ",check_int_data");
1324         else if (btrfs_test_opt(info, CHECK_INTEGRITY))
1325                 seq_puts(seq, ",check_int");
1326         if (info->check_integrity_print_mask)
1327                 seq_printf(seq, ",check_int_print_mask=%d",
1328                                 info->check_integrity_print_mask);
1329 #endif
1330         if (info->metadata_ratio)
1331                 seq_printf(seq, ",metadata_ratio=%u", info->metadata_ratio);
1332         if (btrfs_test_opt(info, PANIC_ON_FATAL_ERROR))
1333                 seq_puts(seq, ",fatal_errors=panic");
1334         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1335                 seq_printf(seq, ",commit=%d", info->commit_interval);
1336 #ifdef CONFIG_BTRFS_DEBUG
1337         if (btrfs_test_opt(info, FRAGMENT_DATA))
1338                 seq_puts(seq, ",fragment=data");
1339         if (btrfs_test_opt(info, FRAGMENT_METADATA))
1340                 seq_puts(seq, ",fragment=metadata");
1341 #endif
1342         if (btrfs_test_opt(info, REF_VERIFY))
1343                 seq_puts(seq, ",ref_verify");
1344         seq_printf(seq, ",subvolid=%llu",
1345                   BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1346         seq_puts(seq, ",subvol=");
1347         seq_dentry(seq, dentry, " \t\n\\");
1348         return 0;
1349 }
1350
1351 static int btrfs_test_super(struct super_block *s, void *data)
1352 {
1353         struct btrfs_fs_info *p = data;
1354         struct btrfs_fs_info *fs_info = btrfs_sb(s);
1355
1356         return fs_info->fs_devices == p->fs_devices;
1357 }
1358
1359 static int btrfs_set_super(struct super_block *s, void *data)
1360 {
1361         int err = set_anon_super(s, data);
1362         if (!err)
1363                 s->s_fs_info = data;
1364         return err;
1365 }
1366
1367 /*
1368  * subvolumes are identified by ino 256
1369  */
1370 static inline int is_subvolume_inode(struct inode *inode)
1371 {
1372         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1373                 return 1;
1374         return 0;
1375 }
1376
1377 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
1378                                    const char *device_name, struct vfsmount *mnt)
1379 {
1380         struct dentry *root;
1381         int ret;
1382
1383         if (!subvol_name) {
1384                 if (!subvol_objectid) {
1385                         ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
1386                                                           &subvol_objectid);
1387                         if (ret) {
1388                                 root = ERR_PTR(ret);
1389                                 goto out;
1390                         }
1391                 }
1392                 subvol_name = get_subvol_name_from_objectid(btrfs_sb(mnt->mnt_sb),
1393                                                             subvol_objectid);
1394                 if (IS_ERR(subvol_name)) {
1395                         root = ERR_CAST(subvol_name);
1396                         subvol_name = NULL;
1397                         goto out;
1398                 }
1399
1400         }
1401
1402         root = mount_subtree(mnt, subvol_name);
1403         /* mount_subtree() drops our reference on the vfsmount. */
1404         mnt = NULL;
1405
1406         if (!IS_ERR(root)) {
1407                 struct super_block *s = root->d_sb;
1408                 struct btrfs_fs_info *fs_info = btrfs_sb(s);
1409                 struct inode *root_inode = d_inode(root);
1410                 u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
1411
1412                 ret = 0;
1413                 if (!is_subvolume_inode(root_inode)) {
1414                         btrfs_err(fs_info, "'%s' is not a valid subvolume",
1415                                subvol_name);
1416                         ret = -EINVAL;
1417                 }
1418                 if (subvol_objectid && root_objectid != subvol_objectid) {
1419                         /*
1420                          * This will also catch a race condition where a
1421                          * subvolume which was passed by ID is renamed and
1422                          * another subvolume is renamed over the old location.
1423                          */
1424                         btrfs_err(fs_info,
1425                                   "subvol '%s' does not match subvolid %llu",
1426                                   subvol_name, subvol_objectid);
1427                         ret = -EINVAL;
1428                 }
1429                 if (ret) {
1430                         dput(root);
1431                         root = ERR_PTR(ret);
1432                         deactivate_locked_super(s);
1433                 }
1434         }
1435
1436 out:
1437         mntput(mnt);
1438         kfree(subvol_name);
1439         return root;
1440 }
1441
1442 static int parse_security_options(char *orig_opts,
1443                                   struct security_mnt_opts *sec_opts)
1444 {
1445         char *secdata = NULL;
1446         int ret = 0;
1447
1448         secdata = alloc_secdata();
1449         if (!secdata)
1450                 return -ENOMEM;
1451         ret = security_sb_copy_data(orig_opts, secdata);
1452         if (ret) {
1453                 free_secdata(secdata);
1454                 return ret;
1455         }
1456         ret = security_sb_parse_opts_str(secdata, sec_opts);
1457         free_secdata(secdata);
1458         return ret;
1459 }
1460
1461 static int setup_security_options(struct btrfs_fs_info *fs_info,
1462                                   struct super_block *sb,
1463                                   struct security_mnt_opts *sec_opts)
1464 {
1465         int ret = 0;
1466
1467         /*
1468          * Call security_sb_set_mnt_opts() to check whether new sec_opts
1469          * is valid.
1470          */
1471         ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
1472         if (ret)
1473                 return ret;
1474
1475 #ifdef CONFIG_SECURITY
1476         if (!fs_info->security_opts.num_mnt_opts) {
1477                 /* first time security setup, copy sec_opts to fs_info */
1478                 memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts));
1479         } else {
1480                 /*
1481                  * Since SELinux (the only one supporting security_mnt_opts)
1482                  * does NOT support changing context during remount/mount of
1483                  * the same sb, this must be the same or part of the same
1484                  * security options, just free it.
1485                  */
1486                 security_free_mnt_opts(sec_opts);
1487         }
1488 #endif
1489         return ret;
1490 }
1491
1492 /*
1493  * Find a superblock for the given device / mount point.
1494  *
1495  * Note: This is based on mount_bdev from fs/super.c with a few additions
1496  *       for multiple device setup.  Make sure to keep it in sync.
1497  */
1498 static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
1499                 int flags, const char *device_name, void *data)
1500 {
1501         struct block_device *bdev = NULL;
1502         struct super_block *s;
1503         struct btrfs_fs_devices *fs_devices = NULL;
1504         struct btrfs_fs_info *fs_info = NULL;
1505         struct security_mnt_opts new_sec_opts;
1506         fmode_t mode = FMODE_READ;
1507         int error = 0;
1508
1509         if (!(flags & SB_RDONLY))
1510                 mode |= FMODE_WRITE;
1511
1512         error = btrfs_parse_early_options(data, mode, fs_type,
1513                                           &fs_devices);
1514         if (error) {
1515                 return ERR_PTR(error);
1516         }
1517
1518         security_init_mnt_opts(&new_sec_opts);
1519         if (data) {
1520                 error = parse_security_options(data, &new_sec_opts);
1521                 if (error)
1522                         return ERR_PTR(error);
1523         }
1524
1525         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1526         if (error)
1527                 goto error_sec_opts;
1528
1529         /*
1530          * Setup a dummy root and fs_info for test/set super.  This is because
1531          * we don't actually fill this stuff out until open_ctree, but we need
1532          * it for searching for existing supers, so this lets us do that and
1533          * then open_ctree will properly initialize everything later.
1534          */
1535         fs_info = kvzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
1536         if (!fs_info) {
1537                 error = -ENOMEM;
1538                 goto error_sec_opts;
1539         }
1540
1541         fs_info->fs_devices = fs_devices;
1542
1543         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1544         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1545         security_init_mnt_opts(&fs_info->security_opts);
1546         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1547                 error = -ENOMEM;
1548                 goto error_fs_info;
1549         }
1550
1551         error = btrfs_open_devices(fs_devices, mode, fs_type);
1552         if (error)
1553                 goto error_fs_info;
1554
1555         if (!(flags & SB_RDONLY) && fs_devices->rw_devices == 0) {
1556                 error = -EACCES;
1557                 goto error_close_devices;
1558         }
1559
1560         bdev = fs_devices->latest_bdev;
1561         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | SB_NOSEC,
1562                  fs_info);
1563         if (IS_ERR(s)) {
1564                 error = PTR_ERR(s);
1565                 goto error_close_devices;
1566         }
1567
1568         if (s->s_root) {
1569                 btrfs_close_devices(fs_devices);
1570                 free_fs_info(fs_info);
1571                 if ((flags ^ s->s_flags) & SB_RDONLY)
1572                         error = -EBUSY;
1573         } else {
1574                 snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
1575                 btrfs_sb(s)->bdev_holder = fs_type;
1576                 error = btrfs_fill_super(s, fs_devices, data);
1577         }
1578         if (error) {
1579                 deactivate_locked_super(s);
1580                 goto error_sec_opts;
1581         }
1582
1583         fs_info = btrfs_sb(s);
1584         error = setup_security_options(fs_info, s, &new_sec_opts);
1585         if (error) {
1586                 deactivate_locked_super(s);
1587                 goto error_sec_opts;
1588         }
1589
1590         return dget(s->s_root);
1591
1592 error_close_devices:
1593         btrfs_close_devices(fs_devices);
1594 error_fs_info:
1595         free_fs_info(fs_info);
1596 error_sec_opts:
1597         security_free_mnt_opts(&new_sec_opts);
1598         return ERR_PTR(error);
1599 }
1600
1601 /*
1602  * Mount function which is called by VFS layer.
1603  *
1604  * In order to allow mounting a subvolume directly, btrfs uses mount_subtree()
1605  * which needs vfsmount* of device's root (/).  This means device's root has to
1606  * be mounted internally in any case.
1607  *
1608  * Operation flow:
1609  *   1. Parse subvol id related options for later use in mount_subvol().
1610  *
1611  *   2. Mount device's root (/) by calling vfs_kern_mount().
1612  *
1613  *      NOTE: vfs_kern_mount() is used by VFS to call btrfs_mount() in the
1614  *      first place. In order to avoid calling btrfs_mount() again, we use
1615  *      different file_system_type which is not registered to VFS by
1616  *      register_filesystem() (btrfs_root_fs_type). As a result,
1617  *      btrfs_mount_root() is called. The return value will be used by
1618  *      mount_subtree() in mount_subvol().
1619  *
1620  *   3. Call mount_subvol() to get the dentry of subvolume. Since there is
1621  *      "btrfs subvolume set-default", mount_subvol() is called always.
1622  */
1623 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1624                 const char *device_name, void *data)
1625 {
1626         struct vfsmount *mnt_root;
1627         struct dentry *root;
1628         fmode_t mode = FMODE_READ;
1629         char *subvol_name = NULL;
1630         u64 subvol_objectid = 0;
1631         int error = 0;
1632
1633         if (!(flags & SB_RDONLY))
1634                 mode |= FMODE_WRITE;
1635
1636         error = btrfs_parse_subvol_options(data, mode,
1637                                           &subvol_name, &subvol_objectid);
1638         if (error) {
1639                 kfree(subvol_name);
1640                 return ERR_PTR(error);
1641         }
1642
1643         /* mount device's root (/) */
1644         mnt_root = vfs_kern_mount(&btrfs_root_fs_type, flags, device_name, data);
1645         if (PTR_ERR_OR_ZERO(mnt_root) == -EBUSY) {
1646                 if (flags & SB_RDONLY) {
1647                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1648                                 flags & ~SB_RDONLY, device_name, data);
1649                 } else {
1650                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1651                                 flags | SB_RDONLY, device_name, data);
1652                         if (IS_ERR(mnt_root)) {
1653                                 root = ERR_CAST(mnt_root);
1654                                 goto out;
1655                         }
1656
1657                         down_write(&mnt_root->mnt_sb->s_umount);
1658                         error = btrfs_remount(mnt_root->mnt_sb, &flags, NULL);
1659                         up_write(&mnt_root->mnt_sb->s_umount);
1660                         if (error < 0) {
1661                                 root = ERR_PTR(error);
1662                                 mntput(mnt_root);
1663                                 goto out;
1664                         }
1665                 }
1666         }
1667         if (IS_ERR(mnt_root)) {
1668                 root = ERR_CAST(mnt_root);
1669                 goto out;
1670         }
1671
1672         /* mount_subvol() will free subvol_name and mnt_root */
1673         root = mount_subvol(subvol_name, subvol_objectid, device_name, mnt_root);
1674
1675 out:
1676         return root;
1677 }
1678
1679 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1680                                      u32 new_pool_size, u32 old_pool_size)
1681 {
1682         if (new_pool_size == old_pool_size)
1683                 return;
1684
1685         fs_info->thread_pool_size = new_pool_size;
1686
1687         btrfs_info(fs_info, "resize thread pool %d -> %d",
1688                old_pool_size, new_pool_size);
1689
1690         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1691         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1692         btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);
1693         btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1694         btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
1695         btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
1696         btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
1697                                 new_pool_size);
1698         btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1699         btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1700         btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1701         btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
1702         btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
1703                                 new_pool_size);
1704 }
1705
1706 static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
1707 {
1708         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1709 }
1710
1711 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1712                                        unsigned long old_opts, int flags)
1713 {
1714         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1715             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1716              (flags & SB_RDONLY))) {
1717                 /* wait for any defraggers to finish */
1718                 wait_event(fs_info->transaction_wait,
1719                            (atomic_read(&fs_info->defrag_running) == 0));
1720                 if (flags & SB_RDONLY)
1721                         sync_filesystem(fs_info->sb);
1722         }
1723 }
1724
1725 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1726                                          unsigned long old_opts)
1727 {
1728         /*
1729          * We need to cleanup all defragable inodes if the autodefragment is
1730          * close or the filesystem is read only.
1731          */
1732         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1733             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) || sb_rdonly(fs_info->sb))) {
1734                 btrfs_cleanup_defrag_inodes(fs_info);
1735         }
1736
1737         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1738 }
1739
1740 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1741 {
1742         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1743         struct btrfs_root *root = fs_info->tree_root;
1744         unsigned old_flags = sb->s_flags;
1745         unsigned long old_opts = fs_info->mount_opt;
1746         unsigned long old_compress_type = fs_info->compress_type;
1747         u64 old_max_inline = fs_info->max_inline;
1748         u32 old_thread_pool_size = fs_info->thread_pool_size;
1749         unsigned int old_metadata_ratio = fs_info->metadata_ratio;
1750         int ret;
1751
1752         sync_filesystem(sb);
1753         btrfs_remount_prepare(fs_info);
1754
1755         if (data) {
1756                 struct security_mnt_opts new_sec_opts;
1757
1758                 security_init_mnt_opts(&new_sec_opts);
1759                 ret = parse_security_options(data, &new_sec_opts);
1760                 if (ret)
1761                         goto restore;
1762                 ret = setup_security_options(fs_info, sb,
1763                                              &new_sec_opts);
1764                 if (ret) {
1765                         security_free_mnt_opts(&new_sec_opts);
1766                         goto restore;
1767                 }
1768         }
1769
1770         ret = btrfs_parse_options(fs_info, data, *flags);
1771         if (ret) {
1772                 ret = -EINVAL;
1773                 goto restore;
1774         }
1775
1776         btrfs_remount_begin(fs_info, old_opts, *flags);
1777         btrfs_resize_thread_pool(fs_info,
1778                 fs_info->thread_pool_size, old_thread_pool_size);
1779
1780         if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
1781                 goto out;
1782
1783         if (*flags & SB_RDONLY) {
1784                 /*
1785                  * this also happens on 'umount -rf' or on shutdown, when
1786                  * the filesystem is busy.
1787                  */
1788                 cancel_work_sync(&fs_info->async_reclaim_work);
1789
1790                 /* wait for the uuid_scan task to finish */
1791                 down(&fs_info->uuid_tree_rescan_sem);
1792                 /* avoid complains from lockdep et al. */
1793                 up(&fs_info->uuid_tree_rescan_sem);
1794
1795                 sb->s_flags |= SB_RDONLY;
1796
1797                 /*
1798                  * Setting SB_RDONLY will put the cleaner thread to
1799                  * sleep at the next loop if it's already active.
1800                  * If it's already asleep, we'll leave unused block
1801                  * groups on disk until we're mounted read-write again
1802                  * unless we clean them up here.
1803                  */
1804                 btrfs_delete_unused_bgs(fs_info);
1805
1806                 btrfs_dev_replace_suspend_for_unmount(fs_info);
1807                 btrfs_scrub_cancel(fs_info);
1808                 btrfs_pause_balance(fs_info);
1809
1810                 ret = btrfs_commit_super(fs_info);
1811                 if (ret)
1812                         goto restore;
1813         } else {
1814                 if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
1815                         btrfs_err(fs_info,
1816                                 "Remounting read-write after error is not allowed");
1817                         ret = -EINVAL;
1818                         goto restore;
1819                 }
1820                 if (fs_info->fs_devices->rw_devices == 0) {
1821                         ret = -EACCES;
1822                         goto restore;
1823                 }
1824
1825                 if (!btrfs_check_rw_degradable(fs_info, NULL)) {
1826                         btrfs_warn(fs_info,
1827                                 "too many missing devices, writeable remount is not allowed");
1828                         ret = -EACCES;
1829                         goto restore;
1830                 }
1831
1832                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1833                         ret = -EINVAL;
1834                         goto restore;
1835                 }
1836
1837                 ret = btrfs_cleanup_fs_roots(fs_info);
1838                 if (ret)
1839                         goto restore;
1840
1841                 /* recover relocation */
1842                 mutex_lock(&fs_info->cleaner_mutex);
1843                 ret = btrfs_recover_relocation(root);
1844                 mutex_unlock(&fs_info->cleaner_mutex);
1845                 if (ret)
1846                         goto restore;
1847
1848                 ret = btrfs_resume_balance_async(fs_info);
1849                 if (ret)
1850                         goto restore;
1851
1852                 ret = btrfs_resume_dev_replace_async(fs_info);
1853                 if (ret) {
1854                         btrfs_warn(fs_info, "failed to resume dev_replace");
1855                         goto restore;
1856                 }
1857
1858                 btrfs_qgroup_rescan_resume(fs_info);
1859
1860                 if (!fs_info->uuid_root) {
1861                         btrfs_info(fs_info, "creating UUID tree");
1862                         ret = btrfs_create_uuid_tree(fs_info);
1863                         if (ret) {
1864                                 btrfs_warn(fs_info,
1865                                            "failed to create the UUID tree %d",
1866                                            ret);
1867                                 goto restore;
1868                         }
1869                 }
1870                 sb->s_flags &= ~SB_RDONLY;
1871
1872                 set_bit(BTRFS_FS_OPEN, &fs_info->flags);
1873         }
1874 out:
1875         wake_up_process(fs_info->transaction_kthread);
1876         btrfs_remount_cleanup(fs_info, old_opts);
1877         return 0;
1878
1879 restore:
1880         /* We've hit an error - don't reset SB_RDONLY */
1881         if (sb_rdonly(sb))
1882                 old_flags |= SB_RDONLY;
1883         sb->s_flags = old_flags;
1884         fs_info->mount_opt = old_opts;
1885         fs_info->compress_type = old_compress_type;
1886         fs_info->max_inline = old_max_inline;
1887         btrfs_resize_thread_pool(fs_info,
1888                 old_thread_pool_size, fs_info->thread_pool_size);
1889         fs_info->metadata_ratio = old_metadata_ratio;
1890         btrfs_remount_cleanup(fs_info, old_opts);
1891         return ret;
1892 }
1893
1894 /* Used to sort the devices by max_avail(descending sort) */
1895 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1896                                        const void *dev_info2)
1897 {
1898         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1899             ((struct btrfs_device_info *)dev_info2)->max_avail)
1900                 return -1;
1901         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1902                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1903                 return 1;
1904         else
1905         return 0;
1906 }
1907
1908 /*
1909  * sort the devices by max_avail, in which max free extent size of each device
1910  * is stored.(Descending Sort)
1911  */
1912 static inline void btrfs_descending_sort_devices(
1913                                         struct btrfs_device_info *devices,
1914                                         size_t nr_devices)
1915 {
1916         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1917              btrfs_cmp_device_free_bytes, NULL);
1918 }
1919
1920 /*
1921  * The helper to calc the free space on the devices that can be used to store
1922  * file data.
1923  */
1924 static int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
1925                                        u64 *free_bytes)
1926 {
1927         struct btrfs_device_info *devices_info;
1928         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1929         struct btrfs_device *device;
1930         u64 skip_space;
1931         u64 type;
1932         u64 avail_space;
1933         u64 min_stripe_size;
1934         int min_stripes = 1, num_stripes = 1;
1935         int i = 0, nr_devices;
1936
1937         /*
1938          * We aren't under the device list lock, so this is racy-ish, but good
1939          * enough for our purposes.
1940          */
1941         nr_devices = fs_info->fs_devices->open_devices;
1942         if (!nr_devices) {
1943                 smp_mb();
1944                 nr_devices = fs_info->fs_devices->open_devices;
1945                 ASSERT(nr_devices);
1946                 if (!nr_devices) {
1947                         *free_bytes = 0;
1948                         return 0;
1949                 }
1950         }
1951
1952         devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
1953                                GFP_KERNEL);
1954         if (!devices_info)
1955                 return -ENOMEM;
1956
1957         /* calc min stripe number for data space allocation */
1958         type = btrfs_data_alloc_profile(fs_info);
1959         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1960                 min_stripes = 2;
1961                 num_stripes = nr_devices;
1962         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1963                 min_stripes = 2;
1964                 num_stripes = 2;
1965         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1966                 min_stripes = 4;
1967                 num_stripes = 4;
1968         }
1969
1970         if (type & BTRFS_BLOCK_GROUP_DUP)
1971                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1972         else
1973                 min_stripe_size = BTRFS_STRIPE_LEN;
1974
1975         rcu_read_lock();
1976         list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
1977                 if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
1978                                                 &device->dev_state) ||
1979                     !device->bdev ||
1980                     test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
1981                         continue;
1982
1983                 if (i >= nr_devices)
1984                         break;
1985
1986                 avail_space = device->total_bytes - device->bytes_used;
1987
1988                 /* align with stripe_len */
1989                 avail_space = div_u64(avail_space, BTRFS_STRIPE_LEN);
1990                 avail_space *= BTRFS_STRIPE_LEN;
1991
1992                 /*
1993                  * In order to avoid overwriting the superblock on the drive,
1994                  * btrfs starts at an offset of at least 1MB when doing chunk
1995                  * allocation.
1996                  */
1997                 skip_space = SZ_1M;
1998
1999                 /*
2000                  * we can use the free space in [0, skip_space - 1], subtract
2001                  * it from the total.
2002                  */
2003                 if (avail_space && avail_space >= skip_space)
2004                         avail_space -= skip_space;
2005                 else
2006                         avail_space = 0;
2007
2008                 if (avail_space < min_stripe_size)
2009                         continue;
2010
2011                 devices_info[i].dev = device;
2012                 devices_info[i].max_avail = avail_space;
2013
2014                 i++;
2015         }
2016         rcu_read_unlock();
2017
2018         nr_devices = i;
2019
2020         btrfs_descending_sort_devices(devices_info, nr_devices);
2021
2022         i = nr_devices - 1;
2023         avail_space = 0;
2024         while (nr_devices >= min_stripes) {
2025                 if (num_stripes > nr_devices)
2026                         num_stripes = nr_devices;
2027
2028                 if (devices_info[i].max_avail >= min_stripe_size) {
2029                         int j;
2030                         u64 alloc_size;
2031
2032                         avail_space += devices_info[i].max_avail * num_stripes;
2033                         alloc_size = devices_info[i].max_avail;
2034                         for (j = i + 1 - num_stripes; j <= i; j++)
2035                                 devices_info[j].max_avail -= alloc_size;
2036                 }
2037                 i--;
2038                 nr_devices--;
2039         }
2040
2041         kfree(devices_info);
2042         *free_bytes = avail_space;
2043         return 0;
2044 }
2045
2046 /*
2047  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
2048  *
2049  * If there's a redundant raid level at DATA block groups, use the respective
2050  * multiplier to scale the sizes.
2051  *
2052  * Unused device space usage is based on simulating the chunk allocator
2053  * algorithm that respects the device sizes and order of allocations.  This is
2054  * a close approximation of the actual use but there are other factors that may
2055  * change the result (like a new metadata chunk).
2056  *
2057  * If metadata is exhausted, f_bavail will be 0.
2058  */
2059 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
2060 {
2061         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
2062         struct btrfs_super_block *disk_super = fs_info->super_copy;
2063         struct list_head *head = &fs_info->space_info;
2064         struct btrfs_space_info *found;
2065         u64 total_used = 0;
2066         u64 total_free_data = 0;
2067         u64 total_free_meta = 0;
2068         int bits = dentry->d_sb->s_blocksize_bits;
2069         __be32 *fsid = (__be32 *)fs_info->fsid;
2070         unsigned factor = 1;
2071         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
2072         int ret;
2073         u64 thresh = 0;
2074         int mixed = 0;
2075
2076         rcu_read_lock();
2077         list_for_each_entry_rcu(found, head, list) {
2078                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
2079                         int i;
2080
2081                         total_free_data += found->disk_total - found->disk_used;
2082                         total_free_data -=
2083                                 btrfs_account_ro_block_groups_free_space(found);
2084
2085                         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
2086                                 if (!list_empty(&found->block_groups[i])) {
2087                                         switch (i) {
2088                                         case BTRFS_RAID_DUP:
2089                                         case BTRFS_RAID_RAID1:
2090                                         case BTRFS_RAID_RAID10:
2091                                                 factor = 2;
2092                                         }
2093                                 }
2094                         }
2095                 }
2096
2097                 /*
2098                  * Metadata in mixed block goup profiles are accounted in data
2099                  */
2100                 if (!mixed && found->flags & BTRFS_BLOCK_GROUP_METADATA) {
2101                         if (found->flags & BTRFS_BLOCK_GROUP_DATA)
2102                                 mixed = 1;
2103                         else
2104                                 total_free_meta += found->disk_total -
2105                                         found->disk_used;
2106                 }
2107
2108                 total_used += found->disk_used;
2109         }
2110
2111         rcu_read_unlock();
2112
2113         buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
2114         buf->f_blocks >>= bits;
2115         buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
2116
2117         /* Account global block reserve as used, it's in logical size already */
2118         spin_lock(&block_rsv->lock);
2119         /* Mixed block groups accounting is not byte-accurate, avoid overflow */
2120         if (buf->f_bfree >= block_rsv->size >> bits)
2121                 buf->f_bfree -= block_rsv->size >> bits;
2122         else
2123                 buf->f_bfree = 0;
2124         spin_unlock(&block_rsv->lock);
2125
2126         buf->f_bavail = div_u64(total_free_data, factor);
2127         ret = btrfs_calc_avail_data_space(fs_info, &total_free_data);
2128         if (ret)
2129                 return ret;
2130         buf->f_bavail += div_u64(total_free_data, factor);
2131         buf->f_bavail = buf->f_bavail >> bits;
2132
2133         /*
2134          * We calculate the remaining metadata space minus global reserve. If
2135          * this is (supposedly) smaller than zero, there's no space. But this
2136          * does not hold in practice, the exhausted state happens where's still
2137          * some positive delta. So we apply some guesswork and compare the
2138          * delta to a 4M threshold.  (Practically observed delta was ~2M.)
2139          *
2140          * We probably cannot calculate the exact threshold value because this
2141          * depends on the internal reservations requested by various
2142          * operations, so some operations that consume a few metadata will
2143          * succeed even if the Avail is zero. But this is better than the other
2144          * way around.
2145          */
2146         thresh = SZ_4M;
2147
2148         if (!mixed && total_free_meta - thresh < block_rsv->size)
2149                 buf->f_bavail = 0;
2150
2151         buf->f_type = BTRFS_SUPER_MAGIC;
2152         buf->f_bsize = dentry->d_sb->s_blocksize;
2153         buf->f_namelen = BTRFS_NAME_LEN;
2154
2155         /* We treat it as constant endianness (it doesn't matter _which_)
2156            because we want the fsid to come out the same whether mounted
2157            on a big-endian or little-endian host */
2158         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
2159         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
2160         /* Mask in the root object ID too, to disambiguate subvols */
2161         buf->f_fsid.val[0] ^= BTRFS_I(d_inode(dentry))->root->objectid >> 32;
2162         buf->f_fsid.val[1] ^= BTRFS_I(d_inode(dentry))->root->objectid;
2163
2164         return 0;
2165 }
2166
2167 static void btrfs_kill_super(struct super_block *sb)
2168 {
2169         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2170         kill_anon_super(sb);
2171         free_fs_info(fs_info);
2172 }
2173
2174 static struct file_system_type btrfs_fs_type = {
2175         .owner          = THIS_MODULE,
2176         .name           = "btrfs",
2177         .mount          = btrfs_mount,
2178         .kill_sb        = btrfs_kill_super,
2179         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2180 };
2181
2182 static struct file_system_type btrfs_root_fs_type = {
2183         .owner          = THIS_MODULE,
2184         .name           = "btrfs",
2185         .mount          = btrfs_mount_root,
2186         .kill_sb        = btrfs_kill_super,
2187         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2188 };
2189
2190 MODULE_ALIAS_FS("btrfs");
2191
2192 static int btrfs_control_open(struct inode *inode, struct file *file)
2193 {
2194         /*
2195          * The control file's private_data is used to hold the
2196          * transaction when it is started and is used to keep
2197          * track of whether a transaction is already in progress.
2198          */
2199         file->private_data = NULL;
2200         return 0;
2201 }
2202
2203 /*
2204  * used by btrfsctl to scan devices when no FS is mounted
2205  */
2206 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
2207                                 unsigned long arg)
2208 {
2209         struct btrfs_ioctl_vol_args *vol;
2210         struct btrfs_fs_devices *fs_devices;
2211         int ret = -ENOTTY;
2212
2213         if (!capable(CAP_SYS_ADMIN))
2214                 return -EPERM;
2215
2216         vol = memdup_user((void __user *)arg, sizeof(*vol));
2217         if (IS_ERR(vol))
2218                 return PTR_ERR(vol);
2219
2220         switch (cmd) {
2221         case BTRFS_IOC_SCAN_DEV:
2222                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2223                                             &btrfs_root_fs_type, &fs_devices);
2224                 break;
2225         case BTRFS_IOC_DEVICES_READY:
2226                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2227                                             &btrfs_root_fs_type, &fs_devices);
2228                 if (ret)
2229                         break;
2230                 ret = !(fs_devices->num_devices == fs_devices->total_devices);
2231                 break;
2232         case BTRFS_IOC_GET_SUPPORTED_FEATURES:
2233                 ret = btrfs_ioctl_get_supported_features((void __user*)arg);
2234                 break;
2235         }
2236
2237         kfree(vol);
2238         return ret;
2239 }
2240
2241 static int btrfs_freeze(struct super_block *sb)
2242 {
2243         struct btrfs_trans_handle *trans;
2244         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2245         struct btrfs_root *root = fs_info->tree_root;
2246
2247         set_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2248         /*
2249          * We don't need a barrier here, we'll wait for any transaction that
2250          * could be in progress on other threads (and do delayed iputs that
2251          * we want to avoid on a frozen filesystem), or do the commit
2252          * ourselves.
2253          */
2254         trans = btrfs_attach_transaction_barrier(root);
2255         if (IS_ERR(trans)) {
2256                 /* no transaction, don't bother */
2257                 if (PTR_ERR(trans) == -ENOENT)
2258                         return 0;
2259                 return PTR_ERR(trans);
2260         }
2261         return btrfs_commit_transaction(trans);
2262 }
2263
2264 static int btrfs_unfreeze(struct super_block *sb)
2265 {
2266         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2267
2268         clear_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2269         return 0;
2270 }
2271
2272 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
2273 {
2274         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
2275         struct btrfs_fs_devices *cur_devices;
2276         struct btrfs_device *dev, *first_dev = NULL;
2277         struct list_head *head;
2278         struct rcu_string *name;
2279
2280         mutex_lock(&fs_info->fs_devices->device_list_mutex);
2281         cur_devices = fs_info->fs_devices;
2282         while (cur_devices) {
2283                 head = &cur_devices->devices;
2284                 list_for_each_entry(dev, head, dev_list) {
2285                         if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state))
2286                                 continue;
2287                         if (!dev->name)
2288                                 continue;
2289                         if (!first_dev || dev->devid < first_dev->devid)
2290                                 first_dev = dev;
2291                 }
2292                 cur_devices = cur_devices->seed;
2293         }
2294
2295         if (first_dev) {
2296                 rcu_read_lock();
2297                 name = rcu_dereference(first_dev->name);
2298                 seq_escape(m, name->str, " \t\n\\");
2299                 rcu_read_unlock();
2300         } else {
2301                 WARN_ON(1);
2302         }
2303         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2304         return 0;
2305 }
2306
2307 static const struct super_operations btrfs_super_ops = {
2308         .drop_inode     = btrfs_drop_inode,
2309         .evict_inode    = btrfs_evict_inode,
2310         .put_super      = btrfs_put_super,
2311         .sync_fs        = btrfs_sync_fs,
2312         .show_options   = btrfs_show_options,
2313         .show_devname   = btrfs_show_devname,
2314         .write_inode    = btrfs_write_inode,
2315         .alloc_inode    = btrfs_alloc_inode,
2316         .destroy_inode  = btrfs_destroy_inode,
2317         .statfs         = btrfs_statfs,
2318         .remount_fs     = btrfs_remount,
2319         .freeze_fs      = btrfs_freeze,
2320         .unfreeze_fs    = btrfs_unfreeze,
2321 };
2322
2323 static const struct file_operations btrfs_ctl_fops = {
2324         .open = btrfs_control_open,
2325         .unlocked_ioctl  = btrfs_control_ioctl,
2326         .compat_ioctl = btrfs_control_ioctl,
2327         .owner   = THIS_MODULE,
2328         .llseek = noop_llseek,
2329 };
2330
2331 static struct miscdevice btrfs_misc = {
2332         .minor          = BTRFS_MINOR,
2333         .name           = "btrfs-control",
2334         .fops           = &btrfs_ctl_fops
2335 };
2336
2337 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2338 MODULE_ALIAS("devname:btrfs-control");
2339
2340 static int __init btrfs_interface_init(void)
2341 {
2342         return misc_register(&btrfs_misc);
2343 }
2344
2345 static void btrfs_interface_exit(void)
2346 {
2347         misc_deregister(&btrfs_misc);
2348 }
2349
2350 static void __init btrfs_print_mod_info(void)
2351 {
2352         pr_info("Btrfs loaded, crc32c=%s"
2353 #ifdef CONFIG_BTRFS_DEBUG
2354                         ", debug=on"
2355 #endif
2356 #ifdef CONFIG_BTRFS_ASSERT
2357                         ", assert=on"
2358 #endif
2359 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2360                         ", integrity-checker=on"
2361 #endif
2362 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
2363                         ", ref-verify=on"
2364 #endif
2365                         "\n",
2366                         btrfs_crc32c_impl());
2367 }
2368
2369 static int __init init_btrfs_fs(void)
2370 {
2371         int err;
2372
2373         err = btrfs_hash_init();
2374         if (err)
2375                 return err;
2376
2377         btrfs_props_init();
2378
2379         err = btrfs_init_sysfs();
2380         if (err)
2381                 goto free_hash;
2382
2383         btrfs_init_compress();
2384
2385         err = btrfs_init_cachep();
2386         if (err)
2387                 goto free_compress;
2388
2389         err = extent_io_init();
2390         if (err)
2391                 goto free_cachep;
2392
2393         err = extent_map_init();
2394         if (err)
2395                 goto free_extent_io;
2396
2397         err = ordered_data_init();
2398         if (err)
2399                 goto free_extent_map;
2400
2401         err = btrfs_delayed_inode_init();
2402         if (err)
2403                 goto free_ordered_data;
2404
2405         err = btrfs_auto_defrag_init();
2406         if (err)
2407                 goto free_delayed_inode;
2408
2409         err = btrfs_delayed_ref_init();
2410         if (err)
2411                 goto free_auto_defrag;
2412
2413         err = btrfs_prelim_ref_init();
2414         if (err)
2415                 goto free_delayed_ref;
2416
2417         err = btrfs_end_io_wq_init();
2418         if (err)
2419                 goto free_prelim_ref;
2420
2421         err = btrfs_interface_init();
2422         if (err)
2423                 goto free_end_io_wq;
2424
2425         btrfs_init_lockdep();
2426
2427         btrfs_print_mod_info();
2428
2429         err = btrfs_run_sanity_tests();
2430         if (err)
2431                 goto unregister_ioctl;
2432
2433         err = register_filesystem(&btrfs_fs_type);
2434         if (err)
2435                 goto unregister_ioctl;
2436
2437         return 0;
2438
2439 unregister_ioctl:
2440         btrfs_interface_exit();
2441 free_end_io_wq:
2442         btrfs_end_io_wq_exit();
2443 free_prelim_ref:
2444         btrfs_prelim_ref_exit();
2445 free_delayed_ref:
2446         btrfs_delayed_ref_exit();
2447 free_auto_defrag:
2448         btrfs_auto_defrag_exit();
2449 free_delayed_inode:
2450         btrfs_delayed_inode_exit();
2451 free_ordered_data:
2452         ordered_data_exit();
2453 free_extent_map:
2454         extent_map_exit();
2455 free_extent_io:
2456         extent_io_exit();
2457 free_cachep:
2458         btrfs_destroy_cachep();
2459 free_compress:
2460         btrfs_exit_compress();
2461         btrfs_exit_sysfs();
2462 free_hash:
2463         btrfs_hash_exit();
2464         return err;
2465 }
2466
2467 static void __exit exit_btrfs_fs(void)
2468 {
2469         btrfs_destroy_cachep();
2470         btrfs_delayed_ref_exit();
2471         btrfs_auto_defrag_exit();
2472         btrfs_delayed_inode_exit();
2473         btrfs_prelim_ref_exit();
2474         ordered_data_exit();
2475         extent_map_exit();
2476         extent_io_exit();
2477         btrfs_interface_exit();
2478         btrfs_end_io_wq_exit();
2479         unregister_filesystem(&btrfs_fs_type);
2480         btrfs_exit_sysfs();
2481         btrfs_cleanup_fs_uuids();
2482         btrfs_exit_compress();
2483         btrfs_hash_exit();
2484 }
2485
2486 late_initcall(init_btrfs_fs);
2487 module_exit(exit_btrfs_fs)
2488
2489 MODULE_LICENSE("GPL");