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 "compat.h"
  46 #include "delayed-inode.h"
  47 #include "ctree.h"
  48 #include "disk-io.h"
  49 #include "transaction.h"
  50 #include "btrfs_inode.h"
  51 #include "print-tree.h"
  52 #include "xattr.h"
  53 #include "volumes.h"
  54 #include "export.h"
  55 #include "compression.h"
  56 #include "rcu-string.h"
  57 #include "dev-replace.h"
  58 #include "free-space-cache.h"
  59 #include "backref.h"
  60 #include "tests/btrfs-tests.h"
  61
  62 #define CREATE_TRACE_POINTS
  63 #include <trace/events/btrfs.h>
  64
  65 static const struct super_operations btrfs_super_ops;
  66 static struct file_system_type btrfs_fs_type;
  67
  68 static const char *btrfs_decode_error(int errno)
  69 {
  70         char *errstr = "unknown";
  71
  72         switch (errno) {
  73         case -EIO:
  74                 errstr = "IO failure";
  75                 break;
  76         case -ENOMEM:
  77                 errstr = "Out of memory";
  78                 break;
  79         case -EROFS:
  80                 errstr = "Readonly filesystem";
  81                 break;
  82         case -EEXIST:
  83                 errstr = "Object already exists";
  84                 break;
  85         case -ENOSPC:
  86                 errstr = "No space left";
  87                 break;
  88         case -ENOENT:
  89                 errstr = "No such entry";
  90                 break;
  91         }
  92
  93         return errstr;
  94 }
  95
  96 static void save_error_info(struct btrfs_fs_info *fs_info)
  97 {
  98         /*
  99          * today we only save the error info into ram.  Long term we'll
 100          * also send it down to the disk
 101          */
 102         set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
 103 }
 104
 105 /* btrfs handle error by forcing the filesystem readonly */
 106 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
 107 {
 108         struct super_block *sb = fs_info->sb;
 109
 110         if (sb->s_flags & MS_RDONLY)
 111                 return;
 112
 113         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 114                 sb->s_flags |= MS_RDONLY;
 115                 btrfs_info(fs_info, "forced readonly");
 116                 /*
 117                  * Note that a running device replace operation is not
 118                  * canceled here although there is no way to update
 119                  * the progress. It would add the risk of a deadlock,
 120                  * therefore the canceling is ommited. The only penalty
 121                  * is that some I/O remains active until the procedure
 122                  * completes. The next time when the filesystem is
 123                  * mounted writeable again, the device replace
 124                  * operation continues.
 125                  */
 126         }
 127 }
 128
 129 #ifdef CONFIG_PRINTK
 130 /*
 131  * __btrfs_std_error decodes expected errors from the caller and
 132  * invokes the approciate error response.
 133  */
 134 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
 135                        unsigned int line, int errno, const char *fmt, ...)
 136 {
 137         struct super_block *sb = fs_info->sb;
 138         const char *errstr;
 139
 140         /*
 141          * Special case: if the error is EROFS, and we're already
 142          * under MS_RDONLY, then it is safe here.
 143          */
 144         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 145                 return;
 146
 147         errstr = btrfs_decode_error(errno);
 148         if (fmt) {
 149                 struct va_format vaf;
 150                 va_list args;
 151
 152                 va_start(args, fmt);
 153                 vaf.fmt = fmt;
 154                 vaf.va = &args;
 155
 156                 printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: errno=%d %s (%pV)\n",
 157                         sb->s_id, function, line, errno, errstr, &vaf);
 158                 va_end(args);
 159         } else {
 160                 printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: errno=%d %s\n",
 161                         sb->s_id, function, line, errno, errstr);
 162         }
 163
 164         /* Don't go through full error handling during mount */
 165         save_error_info(fs_info);
 166         if (sb->s_flags & MS_BORN)
 167                 btrfs_handle_error(fs_info);
 168 }
 169
 170 static const char * const logtypes[] = {
 171         "emergency",
 172         "alert",
 173         "critical",
 174         "error",
 175         "warning",
 176         "notice",
 177         "info",
 178         "debug",
 179 };
 180
 181 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 182 {
 183         struct super_block *sb = fs_info->sb;
 184         char lvl[4];
 185         struct va_format vaf;
 186         va_list args;
 187         const char *type = logtypes[4];
 188         int kern_level;
 189
 190         va_start(args, fmt);
 191
 192         kern_level = printk_get_level(fmt);
 193         if (kern_level) {
 194                 size_t size = printk_skip_level(fmt) - fmt;
 195                 memcpy(lvl, fmt,  size);
 196                 lvl[size] = '\0';
 197                 fmt += size;
 198                 type = logtypes[kern_level - '0'];
 199         } else
 200                 *lvl = '\0';
 201
 202         vaf.fmt = fmt;
 203         vaf.va = &args;
 204
 205         printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
 206
 207         va_end(args);
 208 }
 209
 210 #else
 211
 212 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
 213                        unsigned int line, int errno, const char *fmt, ...)
 214 {
 215         struct super_block *sb = fs_info->sb;
 216
 217         /*
 218          * Special case: if the error is EROFS, and we're already
 219          * under MS_RDONLY, then it is safe here.
 220          */
 221         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 222                 return;
 223
 224         /* Don't go through full error handling during mount */
 225         if (sb->s_flags & MS_BORN) {
 226                 save_error_info(fs_info);
 227                 btrfs_handle_error(fs_info);
 228         }
 229 }
 230 #endif
 231
 232 /*
 233  * We only mark the transaction aborted and then set the file system read-only.
 234  * This will prevent new transactions from starting or trying to join this
 235  * one.
 236  *
 237  * This means that error recovery at the call site is limited to freeing
 238  * any local memory allocations and passing the error code up without
 239  * further cleanup. The transaction should complete as it normally would
 240  * in the call path but will return -EIO.
 241  *
 242  * We'll complete the cleanup in btrfs_end_transaction and
 243  * btrfs_commit_transaction.
 244  */
 245 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 246                                struct btrfs_root *root, const char *function,
 247                                unsigned int line, int errno)
 248 {
 249         /*
 250          * Report first abort since mount
 251          */
 252         if (!test_and_set_bit(BTRFS_FS_STATE_TRANS_ABORTED,
 253                                 &root->fs_info->fs_state)) {
 254                 WARN(1, KERN_DEBUG "btrfs: Transaction aborted (error %d)\n",
 255                                 errno);
 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->blocks_used) {
 261                 const char *errstr;
 262
 263                 errstr = btrfs_decode_error(errno);
 264                 btrfs_warn(root->fs_info,
 265                            "%s:%d: Aborting unused transaction(%s).",
 266                            function, line, errstr);
 267                 return;
 268         }
 269         ACCESS_ONCE(trans->transaction->aborted) = errno;
 270         /* Wake up anybody who may be waiting on this transaction */
 271         wake_up(&root->fs_info->transaction_wait);
 272         wake_up(&root->fs_info->transaction_blocked_wait);
 273         __btrfs_std_error(root->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 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 280                    unsigned int line, int errno, const char *fmt, ...)
 281 {
 282         char *s_id = "<unknown>";
 283         const char *errstr;
 284         struct va_format vaf = { .fmt = fmt };
 285         va_list args;
 286
 287         if (fs_info)
 288                 s_id = fs_info->sb->s_id;
 289
 290         va_start(args, fmt);
 291         vaf.va = &args;
 292
 293         errstr = btrfs_decode_error(errno);
 294         if (fs_info && (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR))
 295                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
 296                         s_id, function, line, &vaf, errno, errstr);
 297
 298         printk(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
 299                s_id, function, line, &vaf, errno, errstr);
 300         va_end(args);
 301         /* Caller calls BUG() */
 302 }
 303
 304 static void btrfs_put_super(struct super_block *sb)
 305 {
 306         (void)close_ctree(btrfs_sb(sb)->tree_root);
 307         /* FIXME: need to fix VFS to return error? */
 308         /* AV: return it _where_?  ->put_super() can be triggered by any number
 309          * of async events, up to and including delivery of SIGKILL to the
 310          * last process that kept it busy.  Or segfault in the aforementioned
 311          * process...  Whom would you report that to?
 312          */
 313 }
 314
 315 enum {
 316         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 317         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 318         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 319         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 320         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 321         Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
 322         Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
 323         Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
 324         Opt_check_integrity, Opt_check_integrity_including_extent_data,
 325         Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
 326         Opt_commit_interval,
 327         Opt_err,
 328 };
 329
 330 static match_table_t tokens = {
 331         {Opt_degraded, "degraded"},
 332         {Opt_subvol, "subvol=%s"},
 333         {Opt_subvolid, "subvolid=%s"},
 334         {Opt_device, "device=%s"},
 335         {Opt_nodatasum, "nodatasum"},
 336         {Opt_nodatacow, "nodatacow"},
 337         {Opt_nobarrier, "nobarrier"},
 338         {Opt_max_inline, "max_inline=%s"},
 339         {Opt_alloc_start, "alloc_start=%s"},
 340         {Opt_thread_pool, "thread_pool=%d"},
 341         {Opt_compress, "compress"},
 342         {Opt_compress_type, "compress=%s"},
 343         {Opt_compress_force, "compress-force"},
 344         {Opt_compress_force_type, "compress-force=%s"},
 345         {Opt_ssd, "ssd"},
 346         {Opt_ssd_spread, "ssd_spread"},
 347         {Opt_nossd, "nossd"},
 348         {Opt_noacl, "noacl"},
 349         {Opt_notreelog, "notreelog"},
 350         {Opt_flushoncommit, "flushoncommit"},
 351         {Opt_ratio, "metadata_ratio=%d"},
 352         {Opt_discard, "discard"},
 353         {Opt_space_cache, "space_cache"},
 354         {Opt_clear_cache, "clear_cache"},
 355         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 356         {Opt_enospc_debug, "enospc_debug"},
 357         {Opt_subvolrootid, "subvolrootid=%d"},
 358         {Opt_defrag, "autodefrag"},
 359         {Opt_inode_cache, "inode_cache"},
 360         {Opt_no_space_cache, "nospace_cache"},
 361         {Opt_recovery, "recovery"},
 362         {Opt_skip_balance, "skip_balance"},
 363         {Opt_check_integrity, "check_int"},
 364         {Opt_check_integrity_including_extent_data, "check_int_data"},
 365         {Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
 366         {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
 367         {Opt_fatal_errors, "fatal_errors=%s"},
 368         {Opt_commit_interval, "commit=%d"},
 369         {Opt_err, NULL},
 370 };
 371
 372 /*
 373  * Regular mount options parser.  Everything that is needed only when
 374  * reading in a new superblock is parsed here.
 375  * XXX JDM: This needs to be cleaned up for remount.
 376  */
 377 int btrfs_parse_options(struct btrfs_root *root, char *options)
 378 {
 379         struct btrfs_fs_info *info = root->fs_info;
 380         substring_t args[MAX_OPT_ARGS];
 381         char *p, *num, *orig = NULL;
 382         u64 cache_gen;
 383         int intarg;
 384         int ret = 0;
 385         char *compress_type;
 386         bool compress_force = false;
 387
 388         cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
 389         if (cache_gen)
 390                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 391
 392         if (!options)
 393                 goto out;
 394
 395         /*
 396          * strsep changes the string, duplicate it because parse_options
 397          * gets called twice
 398          */
 399         options = kstrdup(options, GFP_NOFS);
 400         if (!options)
 401                 return -ENOMEM;
 402
 403         orig = options;
 404
 405         while ((p = strsep(&options, ",")) != NULL) {
 406                 int token;
 407                 if (!*p)
 408                         continue;
 409
 410                 token = match_token(p, tokens, args);
 411                 switch (token) {
 412                 case Opt_degraded:
 413                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 414                         btrfs_set_opt(info->mount_opt, DEGRADED);
 415                         break;
 416                 case Opt_subvol:
 417                 case Opt_subvolid:
 418                 case Opt_subvolrootid:
 419                 case Opt_device:
 420                         /*
 421                          * These are parsed by btrfs_parse_early_options
 422                          * and can be happily ignored here.
 423                          */
 424                         break;
 425                 case Opt_nodatasum:
 426                         printk(KERN_INFO "btrfs: setting nodatasum\n");
 427                         btrfs_set_opt(info->mount_opt, NODATASUM);
 428                         break;
 429                 case Opt_nodatacow:
 430                         if (!btrfs_test_opt(root, COMPRESS) ||
 431                                 !btrfs_test_opt(root, FORCE_COMPRESS)) {
 432                                         printk(KERN_INFO "btrfs: setting nodatacow, compression disabled\n");
 433                         } else {
 434                                 printk(KERN_INFO "btrfs: setting nodatacow\n");
 435                         }
 436                         info->compress_type = BTRFS_COMPRESS_NONE;
 437                         btrfs_clear_opt(info->mount_opt, COMPRESS);
 438                         btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 439                         btrfs_set_opt(info->mount_opt, NODATACOW);
 440                         btrfs_set_opt(info->mount_opt, NODATASUM);
 441                         break;
 442                 case Opt_compress_force:
 443                 case Opt_compress_force_type:
 444                         compress_force = true;
 445                         /* Fallthrough */
 446                 case Opt_compress:
 447                 case Opt_compress_type:
 448                         if (token == Opt_compress ||
 449                             token == Opt_compress_force ||
 450                             strcmp(args[0].from, "zlib") == 0) {
 451                                 compress_type = "zlib";
 452                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 453                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 454                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 455                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 456                         } else if (strcmp(args[0].from, "lzo") == 0) {
 457                                 compress_type = "lzo";
 458                                 info->compress_type = BTRFS_COMPRESS_LZO;
 459                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 460                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 461                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 462                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
 463                         } else if (strncmp(args[0].from, "no", 2) == 0) {
 464                                 compress_type = "no";
 465                                 info->compress_type = BTRFS_COMPRESS_NONE;
 466                                 btrfs_clear_opt(info->mount_opt, COMPRESS);
 467                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 468                                 compress_force = false;
 469                         } else {
 470                                 ret = -EINVAL;
 471                                 goto out;
 472                         }
 473
 474                         if (compress_force) {
 475                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 476                                 pr_info("btrfs: force %s compression\n",
 477                                         compress_type);
 478                         } else
 479                                 pr_info("btrfs: use %s compression\n",
 480                                         compress_type);
 481                         break;
 482                 case Opt_ssd:
 483                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 484                         btrfs_set_opt(info->mount_opt, SSD);
 485                         break;
 486                 case Opt_ssd_spread:
 487                         printk(KERN_INFO "btrfs: use spread ssd "
 488                                "allocation scheme\n");
 489                         btrfs_set_opt(info->mount_opt, SSD);
 490                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 491                         break;
 492                 case Opt_nossd:
 493                         printk(KERN_INFO "btrfs: not using ssd allocation "
 494                                "scheme\n");
 495                         btrfs_set_opt(info->mount_opt, NOSSD);
 496                         btrfs_clear_opt(info->mount_opt, SSD);
 497                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 498                         break;
 499                 case Opt_nobarrier:
 500                         printk(KERN_INFO "btrfs: turning off barriers\n");
 501                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 502                         break;
 503                 case Opt_thread_pool:
 504                         ret = match_int(&args[0], &intarg);
 505                         if (ret) {
 506                                 goto out;
 507                         } else if (intarg > 0) {
 508                                 info->thread_pool_size = intarg;
 509                         } else {
 510                                 ret = -EINVAL;
 511                                 goto out;
 512                         }
 513                         break;
 514                 case Opt_max_inline:
 515                         num = match_strdup(&args[0]);
 516                         if (num) {
 517                                 info->max_inline = memparse(num, NULL);
 518                                 kfree(num);
 519
 520                                 if (info->max_inline) {
 521                                         info->max_inline = max_t(u64,
 522                                                 info->max_inline,
 523                                                 root->sectorsize);
 524                                 }
 525                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 526                                         info->max_inline);
 527                         } else {
 528                                 ret = -ENOMEM;
 529                                 goto out;
 530                         }
 531                         break;
 532                 case Opt_alloc_start:
 533                         num = match_strdup(&args[0]);
 534                         if (num) {
 535                                 mutex_lock(&info->chunk_mutex);
 536                                 info->alloc_start = memparse(num, NULL);
 537                                 mutex_unlock(&info->chunk_mutex);
 538                                 kfree(num);
 539                                 printk(KERN_INFO
 540                                         "btrfs: allocations start at %llu\n",
 541                                         info->alloc_start);
 542                         } else {
 543                                 ret = -ENOMEM;
 544                                 goto out;
 545                         }
 546                         break;
 547                 case Opt_noacl:
 548                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 549                         break;
 550                 case Opt_notreelog:
 551                         printk(KERN_INFO "btrfs: disabling tree log\n");
 552                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 553                         break;
 554                 case Opt_flushoncommit:
 555                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 556                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 557                         break;
 558                 case Opt_ratio:
 559                         ret = match_int(&args[0], &intarg);
 560                         if (ret) {
 561                                 goto out;
 562                         } else if (intarg >= 0) {
 563                                 info->metadata_ratio = intarg;
 564                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 565                                        info->metadata_ratio);
 566                         } else {
 567                                 ret = -EINVAL;
 568                                 goto out;
 569                         }
 570                         break;
 571                 case Opt_discard:
 572                         btrfs_set_opt(info->mount_opt, DISCARD);
 573                         break;
 574                 case Opt_space_cache:
 575                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 576                         break;
 577                 case Opt_rescan_uuid_tree:
 578                         btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
 579                         break;
 580                 case Opt_no_space_cache:
 581                         printk(KERN_INFO "btrfs: disabling disk space caching\n");
 582                         btrfs_clear_opt(info->mount_opt, SPACE_CACHE);
 583                         break;
 584                 case Opt_inode_cache:
 585                         printk(KERN_INFO "btrfs: enabling inode map caching\n");
 586                         btrfs_set_opt(info->mount_opt, INODE_MAP_CACHE);
 587                         break;
 588                 case Opt_clear_cache:
 589                         printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 590                         btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
 591                         break;
 592                 case Opt_user_subvol_rm_allowed:
 593                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 594                         break;
 595                 case Opt_enospc_debug:
 596                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 597                         break;
 598                 case Opt_defrag:
 599                         printk(KERN_INFO "btrfs: enabling auto defrag\n");
 600                         btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
 601                         break;
 602                 case Opt_recovery:
 603                         printk(KERN_INFO "btrfs: enabling auto recovery\n");
 604                         btrfs_set_opt(info->mount_opt, RECOVERY);
 605                         break;
 606                 case Opt_skip_balance:
 607                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 608                         break;
 609 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 610                 case Opt_check_integrity_including_extent_data:
 611                         printk(KERN_INFO "btrfs: enabling check integrity"
 612                                " including extent data\n");
 613                         btrfs_set_opt(info->mount_opt,
 614                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 615                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 616                         break;
 617                 case Opt_check_integrity:
 618                         printk(KERN_INFO "btrfs: enabling check integrity\n");
 619                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 620                         break;
 621                 case Opt_check_integrity_print_mask:
 622                         ret = match_int(&args[0], &intarg);
 623                         if (ret) {
 624                                 goto out;
 625                         } else if (intarg >= 0) {
 626                                 info->check_integrity_print_mask = intarg;
 627                                 printk(KERN_INFO "btrfs:"
 628                                        " check_integrity_print_mask 0x%x\n",
 629                                        info->check_integrity_print_mask);
 630                         } else {
 631                                 ret = -EINVAL;
 632                                 goto out;
 633                         }
 634                         break;
 635 #else
 636                 case Opt_check_integrity_including_extent_data:
 637                 case Opt_check_integrity:
 638                 case Opt_check_integrity_print_mask:
 639                         printk(KERN_ERR "btrfs: support for check_integrity*"
 640                                " not compiled in!\n");
 641                         ret = -EINVAL;
 642                         goto out;
 643 #endif
 644                 case Opt_fatal_errors:
 645                         if (strcmp(args[0].from, "panic") == 0)
 646                                 btrfs_set_opt(info->mount_opt,
 647                                               PANIC_ON_FATAL_ERROR);
 648                         else if (strcmp(args[0].from, "bug") == 0)
 649                                 btrfs_clear_opt(info->mount_opt,
 650                                               PANIC_ON_FATAL_ERROR);
 651                         else {
 652                                 ret = -EINVAL;
 653                                 goto out;
 654                         }
 655                         break;
 656                 case Opt_commit_interval:
 657                         intarg = 0;
 658                         ret = match_int(&args[0], &intarg);
 659                         if (ret < 0) {
 660                                 printk(KERN_ERR
 661                                         "btrfs: invalid commit interval\n");
 662                                 ret = -EINVAL;
 663                                 goto out;
 664                         }
 665                         if (intarg > 0) {
 666                                 if (intarg > 300) {
 667                                         printk(KERN_WARNING
 668                                             "btrfs: excessive commit interval %d\n",
 669                                                         intarg);
 670                                 }
 671                                 info->commit_interval = intarg;
 672                         } else {
 673                                 printk(KERN_INFO
 674                                     "btrfs: using default commit interval %ds\n",
 675                                     BTRFS_DEFAULT_COMMIT_INTERVAL);
 676                                 info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
 677                         }
 678                         break;
 679                 case Opt_err:
 680                         printk(KERN_INFO "btrfs: unrecognized mount option "
 681                                "'%s'\n", p);
 682                         ret = -EINVAL;
 683                         goto out;
 684                 default:
 685                         break;
 686                 }
 687         }
 688 out:
 689         if (!ret && btrfs_test_opt(root, SPACE_CACHE))
 690                 printk(KERN_INFO "btrfs: disk space caching is enabled\n");
 691         kfree(orig);
 692         return ret;
 693 }
 694
 695 /*
 696  * Parse mount options that are required early in the mount process.
 697  *
 698  * All other options will be parsed on much later in the mount process and
 699  * only when we need to allocate a new super block.
 700  */
 701 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 702                 void *holder, char **subvol_name, u64 *subvol_objectid,
 703                 struct btrfs_fs_devices **fs_devices)
 704 {
 705         substring_t args[MAX_OPT_ARGS];
 706         char *device_name, *opts, *orig, *p;
 707         char *num = NULL;
 708         int error = 0;
 709
 710         if (!options)
 711                 return 0;
 712
 713         /*
 714          * strsep changes the string, duplicate it because parse_options
 715          * gets called twice
 716          */
 717         opts = kstrdup(options, GFP_KERNEL);
 718         if (!opts)
 719                 return -ENOMEM;
 720         orig = opts;
 721
 722         while ((p = strsep(&opts, ",")) != NULL) {
 723                 int token;
 724                 if (!*p)
 725                         continue;
 726
 727                 token = match_token(p, tokens, args);
 728                 switch (token) {
 729                 case Opt_subvol:
 730                         kfree(*subvol_name);
 731                         *subvol_name = match_strdup(&args[0]);
 732                         if (!*subvol_name) {
 733                                 error = -ENOMEM;
 734                                 goto out;
 735                         }
 736                         break;
 737                 case Opt_subvolid:
 738                         num = match_strdup(&args[0]);
 739                         if (num) {
 740                                 *subvol_objectid = memparse(num, NULL);
 741                                 kfree(num);
 742                                 /* we want the original fs_tree */
 743                                 if (!*subvol_objectid)
 744                                         *subvol_objectid =
 745                                                 BTRFS_FS_TREE_OBJECTID;
 746                         } else {
 747                                 error = -EINVAL;
 748                                 goto out;
 749                         }
 750                         break;
 751                 case Opt_subvolrootid:
 752                         printk(KERN_WARNING
 753                                 "btrfs: 'subvolrootid' mount option is deprecated and has no effect\n");
 754                         break;
 755                 case Opt_device:
 756                         device_name = match_strdup(&args[0]);
 757                         if (!device_name) {
 758                                 error = -ENOMEM;
 759                                 goto out;
 760                         }
 761                         error = btrfs_scan_one_device(device_name,
 762                                         flags, holder, fs_devices);
 763                         kfree(device_name);
 764                         if (error)
 765                                 goto out;
 766                         break;
 767                 default:
 768                         break;
 769                 }
 770         }
 771
 772 out:
 773         kfree(orig);
 774         return error;
 775 }
 776
 777 static struct dentry *get_default_root(struct super_block *sb,
 778                                        u64 subvol_objectid)
 779 {
 780         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 781         struct btrfs_root *root = fs_info->tree_root;
 782         struct btrfs_root *new_root;
 783         struct btrfs_dir_item *di;
 784         struct btrfs_path *path;
 785         struct btrfs_key location;
 786         struct inode *inode;
 787         u64 dir_id;
 788         int new = 0;
 789
 790         /*
 791          * We have a specific subvol we want to mount, just setup location and
 792          * go look up the root.
 793          */
 794         if (subvol_objectid) {
 795                 location.objectid = subvol_objectid;
 796                 location.type = BTRFS_ROOT_ITEM_KEY;
 797                 location.offset = (u64)-1;
 798                 goto find_root;
 799         }
 800
 801         path = btrfs_alloc_path();
 802         if (!path)
 803                 return ERR_PTR(-ENOMEM);
 804         path->leave_spinning = 1;
 805
 806         /*
 807          * Find the "default" dir item which points to the root item that we
 808          * will mount by default if we haven't been given a specific subvolume
 809          * to mount.
 810          */
 811         dir_id = btrfs_super_root_dir(fs_info->super_copy);
 812         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 813         if (IS_ERR(di)) {
 814                 btrfs_free_path(path);
 815                 return ERR_CAST(di);
 816         }
 817         if (!di) {
 818                 /*
 819                  * Ok the default dir item isn't there.  This is weird since
 820                  * it's always been there, but don't freak out, just try and
 821                  * mount to root most subvolume.
 822                  */
 823                 btrfs_free_path(path);
 824                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
 825                 new_root = fs_info->fs_root;
 826                 goto setup_root;
 827         }
 828
 829         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 830         btrfs_free_path(path);
 831
 832 find_root:
 833         new_root = btrfs_read_fs_root_no_name(fs_info, &location);
 834         if (IS_ERR(new_root))
 835                 return ERR_CAST(new_root);
 836
 837         dir_id = btrfs_root_dirid(&new_root->root_item);
 838 setup_root:
 839         location.objectid = dir_id;
 840         location.type = BTRFS_INODE_ITEM_KEY;
 841         location.offset = 0;
 842
 843         inode = btrfs_iget(sb, &location, new_root, &new);
 844         if (IS_ERR(inode))
 845                 return ERR_CAST(inode);
 846
 847         /*
 848          * If we're just mounting the root most subvol put the inode and return
 849          * a reference to the dentry.  We will have already gotten a reference
 850          * to the inode in btrfs_fill_super so we're good to go.
 851          */
 852         if (!new && sb->s_root->d_inode == inode) {
 853                 iput(inode);
 854                 return dget(sb->s_root);
 855         }
 856
 857         return d_obtain_alias(inode);
 858 }
 859
 860 static int btrfs_fill_super(struct super_block *sb,
 861                             struct btrfs_fs_devices *fs_devices,
 862                             void *data, int silent)
 863 {
 864         struct inode *inode;
 865         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 866         struct btrfs_key key;
 867         int err;
 868
 869         sb->s_maxbytes = MAX_LFS_FILESIZE;
 870         sb->s_magic = BTRFS_SUPER_MAGIC;
 871         sb->s_op = &btrfs_super_ops;
 872         sb->s_d_op = &btrfs_dentry_operations;
 873         sb->s_export_op = &btrfs_export_ops;
 874         sb->s_xattr = btrfs_xattr_handlers;
 875         sb->s_time_gran = 1;
 876 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 877         sb->s_flags |= MS_POSIXACL;
 878 #endif
 879         sb->s_flags |= MS_I_VERSION;
 880         err = open_ctree(sb, fs_devices, (char *)data);
 881         if (err) {
 882                 printk("btrfs: open_ctree failed\n");
 883                 return err;
 884         }
 885
 886         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 887         key.type = BTRFS_INODE_ITEM_KEY;
 888         key.offset = 0;
 889         inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
 890         if (IS_ERR(inode)) {
 891                 err = PTR_ERR(inode);
 892                 goto fail_close;
 893         }
 894
 895         sb->s_root = d_make_root(inode);
 896         if (!sb->s_root) {
 897                 err = -ENOMEM;
 898                 goto fail_close;
 899         }
 900
 901         save_mount_options(sb, data);
 902         cleancache_init_fs(sb);
 903         sb->s_flags |= MS_ACTIVE;
 904         return 0;
 905
 906 fail_close:
 907         close_ctree(fs_info->tree_root);
 908         return err;
 909 }
 910
 911 int btrfs_sync_fs(struct super_block *sb, int wait)
 912 {
 913         struct btrfs_trans_handle *trans;
 914         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 915         struct btrfs_root *root = fs_info->tree_root;
 916
 917         trace_btrfs_sync_fs(wait);
 918
 919         if (!wait) {
 920                 filemap_flush(fs_info->btree_inode->i_mapping);
 921                 return 0;
 922         }
 923
 924         btrfs_wait_all_ordered_extents(fs_info, 1);
 925
 926         trans = btrfs_attach_transaction_barrier(root);
 927         if (IS_ERR(trans)) {
 928                 /* no transaction, don't bother */
 929                 if (PTR_ERR(trans) == -ENOENT)
 930                         return 0;
 931                 return PTR_ERR(trans);
 932         }
 933         return btrfs_commit_transaction(trans, root);
 934 }
 935
 936 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 937 {
 938         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
 939         struct btrfs_root *root = info->tree_root;
 940         char *compress_type;
 941
 942         if (btrfs_test_opt(root, DEGRADED))
 943                 seq_puts(seq, ",degraded");
 944         if (btrfs_test_opt(root, NODATASUM))
 945                 seq_puts(seq, ",nodatasum");
 946         if (btrfs_test_opt(root, NODATACOW))
 947                 seq_puts(seq, ",nodatacow");
 948         if (btrfs_test_opt(root, NOBARRIER))
 949                 seq_puts(seq, ",nobarrier");
 950         if (info->max_inline != 8192 * 1024)
 951                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
 952         if (info->alloc_start != 0)
 953                 seq_printf(seq, ",alloc_start=%llu", info->alloc_start);
 954         if (info->thread_pool_size !=  min_t(unsigned long,
 955                                              num_online_cpus() + 2, 8))
 956                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 957         if (btrfs_test_opt(root, COMPRESS)) {
 958                 if (info->compress_type == BTRFS_COMPRESS_ZLIB)
 959                         compress_type = "zlib";
 960                 else
 961                         compress_type = "lzo";
 962                 if (btrfs_test_opt(root, FORCE_COMPRESS))
 963                         seq_printf(seq, ",compress-force=%s", compress_type);
 964                 else
 965                         seq_printf(seq, ",compress=%s", compress_type);
 966         }
 967         if (btrfs_test_opt(root, NOSSD))
 968                 seq_puts(seq, ",nossd");
 969         if (btrfs_test_opt(root, SSD_SPREAD))
 970                 seq_puts(seq, ",ssd_spread");
 971         else if (btrfs_test_opt(root, SSD))
 972                 seq_puts(seq, ",ssd");
 973         if (btrfs_test_opt(root, NOTREELOG))
 974                 seq_puts(seq, ",notreelog");
 975         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 976                 seq_puts(seq, ",flushoncommit");
 977         if (btrfs_test_opt(root, DISCARD))
 978                 seq_puts(seq, ",discard");
 979         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 980                 seq_puts(seq, ",noacl");
 981         if (btrfs_test_opt(root, SPACE_CACHE))
 982                 seq_puts(seq, ",space_cache");
 983         else
 984                 seq_puts(seq, ",nospace_cache");
 985         if (btrfs_test_opt(root, RESCAN_UUID_TREE))
 986                 seq_puts(seq, ",rescan_uuid_tree");
 987         if (btrfs_test_opt(root, CLEAR_CACHE))
 988                 seq_puts(seq, ",clear_cache");
 989         if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
 990                 seq_puts(seq, ",user_subvol_rm_allowed");
 991         if (btrfs_test_opt(root, ENOSPC_DEBUG))
 992                 seq_puts(seq, ",enospc_debug");
 993         if (btrfs_test_opt(root, AUTO_DEFRAG))
 994                 seq_puts(seq, ",autodefrag");
 995         if (btrfs_test_opt(root, INODE_MAP_CACHE))
 996                 seq_puts(seq, ",inode_cache");
 997         if (btrfs_test_opt(root, SKIP_BALANCE))
 998                 seq_puts(seq, ",skip_balance");
 999         if (btrfs_test_opt(root, RECOVERY))
1000                 seq_puts(seq, ",recovery");
1001 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1002         if (btrfs_test_opt(root, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
1003                 seq_puts(seq, ",check_int_data");
1004         else if (btrfs_test_opt(root, CHECK_INTEGRITY))
1005                 seq_puts(seq, ",check_int");
1006         if (info->check_integrity_print_mask)
1007                 seq_printf(seq, ",check_int_print_mask=%d",
1008                                 info->check_integrity_print_mask);
1009 #endif
1010         if (info->metadata_ratio)
1011                 seq_printf(seq, ",metadata_ratio=%d",
1012                                 info->metadata_ratio);
1013         if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
1014                 seq_puts(seq, ",fatal_errors=panic");
1015         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1016                 seq_printf(seq, ",commit=%d", info->commit_interval);
1017         return 0;
1018 }
1019
1020 static int btrfs_test_super(struct super_block *s, void *data)
1021 {
1022         struct btrfs_fs_info *p = data;
1023         struct btrfs_fs_info *fs_info = btrfs_sb(s);
1024
1025         return fs_info->fs_devices == p->fs_devices;
1026 }
1027
1028 static int btrfs_set_super(struct super_block *s, void *data)
1029 {
1030         int err = set_anon_super(s, data);
1031         if (!err)
1032                 s->s_fs_info = data;
1033         return err;
1034 }
1035
1036 /*
1037  * subvolumes are identified by ino 256
1038  */
1039 static inline int is_subvolume_inode(struct inode *inode)
1040 {
1041         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1042                 return 1;
1043         return 0;
1044 }
1045
1046 /*
1047  * This will strip out the subvol=%s argument for an argument string and add
1048  * subvolid=0 to make sure we get the actual tree root for path walking to the
1049  * subvol we want.
1050  */
1051 static char *setup_root_args(char *args)
1052 {
1053         unsigned len = strlen(args) + 2 + 1;
1054         char *src, *dst, *buf;
1055
1056         /*
1057          * We need the same args as before, but with this substitution:
1058          * s!subvol=[^,]+!subvolid=0!
1059          *
1060          * Since the replacement string is up to 2 bytes longer than the
1061          * original, allocate strlen(args) + 2 + 1 bytes.
1062          */
1063
1064         src = strstr(args, "subvol=");
1065         /* This shouldn't happen, but just in case.. */
1066         if (!src)
1067                 return NULL;
1068
1069         buf = dst = kmalloc(len, GFP_NOFS);
1070         if (!buf)
1071                 return NULL;
1072
1073         /*
1074          * If the subvol= arg is not at the start of the string,
1075          * copy whatever precedes it into buf.
1076          */
1077         if (src != args) {
1078                 *src++ = '\0';
1079                 strcpy(buf, args);
1080                 dst += strlen(args);
1081         }
1082
1083         strcpy(dst, "subvolid=0");
1084         dst += strlen("subvolid=0");
1085
1086         /*
1087          * If there is a "," after the original subvol=... string,
1088          * copy that suffix into our buffer.  Otherwise, we're done.
1089          */
1090         src = strchr(src, ',');
1091         if (src)
1092                 strcpy(dst, src);
1093
1094         return buf;
1095 }
1096
1097 static struct dentry *mount_subvol(const char *subvol_name, int flags,
1098                                    const char *device_name, char *data)
1099 {
1100         struct dentry *root;
1101         struct vfsmount *mnt;
1102         char *newargs;
1103
1104         newargs = setup_root_args(data);
1105         if (!newargs)
1106                 return ERR_PTR(-ENOMEM);
1107         mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
1108                              newargs);
1109         kfree(newargs);
1110         if (IS_ERR(mnt))
1111                 return ERR_CAST(mnt);
1112
1113         root = mount_subtree(mnt, subvol_name);
1114
1115         if (!IS_ERR(root) && !is_subvolume_inode(root->d_inode)) {
1116                 struct super_block *s = root->d_sb;
1117                 dput(root);
1118                 root = ERR_PTR(-EINVAL);
1119                 deactivate_locked_super(s);
1120                 printk(KERN_ERR "btrfs: '%s' is not a valid subvolume\n",
1121                                 subvol_name);
1122         }
1123
1124         return root;
1125 }
1126
1127 /*
1128  * Find a superblock for the given device / mount point.
1129  *
1130  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
1131  *        for multiple device setup.  Make sure to keep it in sync.
1132  */
1133 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1134                 const char *device_name, void *data)
1135 {
1136         struct block_device *bdev = NULL;
1137         struct super_block *s;
1138         struct dentry *root;
1139         struct btrfs_fs_devices *fs_devices = NULL;
1140         struct btrfs_fs_info *fs_info = NULL;
1141         fmode_t mode = FMODE_READ;
1142         char *subvol_name = NULL;
1143         u64 subvol_objectid = 0;
1144         int error = 0;
1145
1146         if (!(flags & MS_RDONLY))
1147                 mode |= FMODE_WRITE;
1148
1149         error = btrfs_parse_early_options(data, mode, fs_type,
1150                                           &subvol_name, &subvol_objectid,
1151                                           &fs_devices);
1152         if (error) {
1153                 kfree(subvol_name);
1154                 return ERR_PTR(error);
1155         }
1156
1157         if (subvol_name) {
1158                 root = mount_subvol(subvol_name, flags, device_name, data);
1159                 kfree(subvol_name);
1160                 return root;
1161         }
1162
1163         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1164         if (error)
1165                 return ERR_PTR(error);
1166
1167         /*
1168          * Setup a dummy root and fs_info for test/set super.  This is because
1169          * we don't actually fill this stuff out until open_ctree, but we need
1170          * it for searching for existing supers, so this lets us do that and
1171          * then open_ctree will properly initialize everything later.
1172          */
1173         fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
1174         if (!fs_info)
1175                 return ERR_PTR(-ENOMEM);
1176
1177         fs_info->fs_devices = fs_devices;
1178
1179         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1180         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1181         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1182                 error = -ENOMEM;
1183                 goto error_fs_info;
1184         }
1185
1186         error = btrfs_open_devices(fs_devices, mode, fs_type);
1187         if (error)
1188                 goto error_fs_info;
1189
1190         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
1191                 error = -EACCES;
1192                 goto error_close_devices;
1193         }
1194
1195         bdev = fs_devices->latest_bdev;
1196         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | MS_NOSEC,
1197                  fs_info);
1198         if (IS_ERR(s)) {
1199                 error = PTR_ERR(s);
1200                 goto error_close_devices;
1201         }
1202
1203         if (s->s_root) {
1204                 btrfs_close_devices(fs_devices);
1205                 free_fs_info(fs_info);
1206                 if ((flags ^ s->s_flags) & MS_RDONLY)
1207                         error = -EBUSY;
1208         } else {
1209                 char b[BDEVNAME_SIZE];
1210
1211                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
1212                 btrfs_sb(s)->bdev_holder = fs_type;
1213                 error = btrfs_fill_super(s, fs_devices, data,
1214                                          flags & MS_SILENT ? 1 : 0);
1215         }
1216
1217         root = !error ? get_default_root(s, subvol_objectid) : ERR_PTR(error);
1218         if (IS_ERR(root))
1219                 deactivate_locked_super(s);
1220
1221         return root;
1222
1223 error_close_devices:
1224         btrfs_close_devices(fs_devices);
1225 error_fs_info:
1226         free_fs_info(fs_info);
1227         return ERR_PTR(error);
1228 }
1229
1230 static void btrfs_set_max_workers(struct btrfs_workers *workers, int new_limit)
1231 {
1232         spin_lock_irq(&workers->lock);
1233         workers->max_workers = new_limit;
1234         spin_unlock_irq(&workers->lock);
1235 }
1236
1237 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1238                                      int new_pool_size, int old_pool_size)
1239 {
1240         if (new_pool_size == old_pool_size)
1241                 return;
1242
1243         fs_info->thread_pool_size = new_pool_size;
1244
1245         printk(KERN_INFO "btrfs: resize thread pool %d -> %d\n",
1246                old_pool_size, new_pool_size);
1247
1248         btrfs_set_max_workers(&fs_info->generic_worker, new_pool_size);
1249         btrfs_set_max_workers(&fs_info->workers, new_pool_size);
1250         btrfs_set_max_workers(&fs_info->delalloc_workers, new_pool_size);
1251         btrfs_set_max_workers(&fs_info->submit_workers, new_pool_size);
1252         btrfs_set_max_workers(&fs_info->caching_workers, new_pool_size);
1253         btrfs_set_max_workers(&fs_info->fixup_workers, new_pool_size);
1254         btrfs_set_max_workers(&fs_info->endio_workers, new_pool_size);
1255         btrfs_set_max_workers(&fs_info->endio_meta_workers, new_pool_size);
1256         btrfs_set_max_workers(&fs_info->endio_meta_write_workers, new_pool_size);
1257         btrfs_set_max_workers(&fs_info->endio_write_workers, new_pool_size);
1258         btrfs_set_max_workers(&fs_info->endio_freespace_worker, new_pool_size);
1259         btrfs_set_max_workers(&fs_info->delayed_workers, new_pool_size);
1260         btrfs_set_max_workers(&fs_info->readahead_workers, new_pool_size);
1261         btrfs_set_max_workers(&fs_info->scrub_wr_completion_workers,
1262                               new_pool_size);
1263 }
1264
1265 static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
1266 {
1267         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1268 }
1269
1270 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1271                                        unsigned long old_opts, int flags)
1272 {
1273         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1274             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1275              (flags & MS_RDONLY))) {
1276                 /* wait for any defraggers to finish */
1277                 wait_event(fs_info->transaction_wait,
1278                            (atomic_read(&fs_info->defrag_running) == 0));
1279                 if (flags & MS_RDONLY)
1280                         sync_filesystem(fs_info->sb);
1281         }
1282 }
1283
1284 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1285                                          unsigned long old_opts)
1286 {
1287         /*
1288          * We need cleanup all defragable inodes if the autodefragment is
1289          * close or the fs is R/O.
1290          */
1291         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1292             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1293              (fs_info->sb->s_flags & MS_RDONLY))) {
1294                 btrfs_cleanup_defrag_inodes(fs_info);
1295         }
1296
1297         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1298 }
1299
1300 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1301 {
1302         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1303         struct btrfs_root *root = fs_info->tree_root;
1304         unsigned old_flags = sb->s_flags;
1305         unsigned long old_opts = fs_info->mount_opt;
1306         unsigned long old_compress_type = fs_info->compress_type;
1307         u64 old_max_inline = fs_info->max_inline;
1308         u64 old_alloc_start = fs_info->alloc_start;
1309         int old_thread_pool_size = fs_info->thread_pool_size;
1310         unsigned int old_metadata_ratio = fs_info->metadata_ratio;
1311         int ret;
1312
1313         btrfs_remount_prepare(fs_info);
1314
1315         ret = btrfs_parse_options(root, data);
1316         if (ret) {
1317                 ret = -EINVAL;
1318                 goto restore;
1319         }
1320
1321         btrfs_remount_begin(fs_info, old_opts, *flags);
1322         btrfs_resize_thread_pool(fs_info,
1323                 fs_info->thread_pool_size, old_thread_pool_size);
1324
1325         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1326                 goto out;
1327
1328         if (*flags & MS_RDONLY) {
1329                 /*
1330                  * this also happens on 'umount -rf' or on shutdown, when
1331                  * the filesystem is busy.
1332                  */
1333                 sb->s_flags |= MS_RDONLY;
1334
1335                 btrfs_dev_replace_suspend_for_unmount(fs_info);
1336                 btrfs_scrub_cancel(fs_info);
1337                 btrfs_pause_balance(fs_info);
1338
1339                 ret = btrfs_commit_super(root);
1340                 if (ret)
1341                         goto restore;
1342         } else {
1343                 if (fs_info->fs_devices->rw_devices == 0) {
1344                         ret = -EACCES;
1345                         goto restore;
1346                 }
1347
1348                 if (fs_info->fs_devices->missing_devices >
1349                      fs_info->num_tolerated_disk_barrier_failures &&
1350                     !(*flags & MS_RDONLY)) {
1351                         printk(KERN_WARNING
1352                                "Btrfs: too many missing devices, writeable remount is not allowed\n");
1353                         ret = -EACCES;
1354                         goto restore;
1355                 }
1356
1357                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1358                         ret = -EINVAL;
1359                         goto restore;
1360                 }
1361
1362                 ret = btrfs_cleanup_fs_roots(fs_info);
1363                 if (ret)
1364                         goto restore;
1365
1366                 /* recover relocation */
1367                 ret = btrfs_recover_relocation(root);
1368                 if (ret)
1369                         goto restore;
1370
1371                 ret = btrfs_resume_balance_async(fs_info);
1372                 if (ret)
1373                         goto restore;
1374
1375                 ret = btrfs_resume_dev_replace_async(fs_info);
1376                 if (ret) {
1377                         pr_warn("btrfs: failed to resume dev_replace\n");
1378                         goto restore;
1379                 }
1380                 sb->s_flags &= ~MS_RDONLY;
1381         }
1382 out:
1383         btrfs_remount_cleanup(fs_info, old_opts);
1384         return 0;
1385
1386 restore:
1387         /* We've hit an error - don't reset MS_RDONLY */
1388         if (sb->s_flags & MS_RDONLY)
1389                 old_flags |= MS_RDONLY;
1390         sb->s_flags = old_flags;
1391         fs_info->mount_opt = old_opts;
1392         fs_info->compress_type = old_compress_type;
1393         fs_info->max_inline = old_max_inline;
1394         mutex_lock(&fs_info->chunk_mutex);
1395         fs_info->alloc_start = old_alloc_start;
1396         mutex_unlock(&fs_info->chunk_mutex);
1397         btrfs_resize_thread_pool(fs_info,
1398                 old_thread_pool_size, fs_info->thread_pool_size);
1399         fs_info->metadata_ratio = old_metadata_ratio;
1400         btrfs_remount_cleanup(fs_info, old_opts);
1401         return ret;
1402 }
1403
1404 /* Used to sort the devices by max_avail(descending sort) */
1405 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1406                                        const void *dev_info2)
1407 {
1408         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1409             ((struct btrfs_device_info *)dev_info2)->max_avail)
1410                 return -1;
1411         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1412                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1413                 return 1;
1414         else
1415         return 0;
1416 }
1417
1418 /*
1419  * sort the devices by max_avail, in which max free extent size of each device
1420  * is stored.(Descending Sort)
1421  */
1422 static inline void btrfs_descending_sort_devices(
1423                                         struct btrfs_device_info *devices,
1424                                         size_t nr_devices)
1425 {
1426         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1427              btrfs_cmp_device_free_bytes, NULL);
1428 }
1429
1430 /*
1431  * The helper to calc the free space on the devices that can be used to store
1432  * file data.
1433  */
1434 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
1435 {
1436         struct btrfs_fs_info *fs_info = root->fs_info;
1437         struct btrfs_device_info *devices_info;
1438         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1439         struct btrfs_device *device;
1440         u64 skip_space;
1441         u64 type;
1442         u64 avail_space;
1443         u64 used_space;
1444         u64 min_stripe_size;
1445         int min_stripes = 1, num_stripes = 1;
1446         int i = 0, nr_devices;
1447         int ret;
1448
1449         nr_devices = fs_info->fs_devices->open_devices;
1450         BUG_ON(!nr_devices);
1451
1452         devices_info = kmalloc(sizeof(*devices_info) * nr_devices,
1453                                GFP_NOFS);
1454         if (!devices_info)
1455                 return -ENOMEM;
1456
1457         /* calc min stripe number for data space alloction */
1458         type = btrfs_get_alloc_profile(root, 1);
1459         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1460                 min_stripes = 2;
1461                 num_stripes = nr_devices;
1462         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1463                 min_stripes = 2;
1464                 num_stripes = 2;
1465         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1466                 min_stripes = 4;
1467                 num_stripes = 4;
1468         }
1469
1470         if (type & BTRFS_BLOCK_GROUP_DUP)
1471                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1472         else
1473                 min_stripe_size = BTRFS_STRIPE_LEN;
1474
1475         list_for_each_entry(device, &fs_devices->devices, dev_list) {
1476                 if (!device->in_fs_metadata || !device->bdev ||
1477                     device->is_tgtdev_for_dev_replace)
1478                         continue;
1479
1480                 avail_space = device->total_bytes - device->bytes_used;
1481
1482                 /* align with stripe_len */
1483                 do_div(avail_space, BTRFS_STRIPE_LEN);
1484                 avail_space *= BTRFS_STRIPE_LEN;
1485
1486                 /*
1487                  * In order to avoid overwritting the superblock on the drive,
1488                  * btrfs starts at an offset of at least 1MB when doing chunk
1489                  * allocation.
1490                  */
1491                 skip_space = 1024 * 1024;
1492
1493                 /* user can set the offset in fs_info->alloc_start. */
1494                 if (fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1495                     device->total_bytes)
1496                         skip_space = max(fs_info->alloc_start, skip_space);
1497
1498                 /*
1499                  * btrfs can not use the free space in [0, skip_space - 1],
1500                  * we must subtract it from the total. In order to implement
1501                  * it, we account the used space in this range first.
1502                  */
1503                 ret = btrfs_account_dev_extents_size(device, 0, skip_space - 1,
1504                                                      &used_space);
1505                 if (ret) {
1506                         kfree(devices_info);
1507                         return ret;
1508                 }
1509
1510                 /* calc the free space in [0, skip_space - 1] */
1511                 skip_space -= used_space;
1512
1513                 /*
1514                  * we can use the free space in [0, skip_space - 1], subtract
1515                  * it from the total.
1516                  */
1517                 if (avail_space && avail_space >= skip_space)
1518                         avail_space -= skip_space;
1519                 else
1520                         avail_space = 0;
1521
1522                 if (avail_space < min_stripe_size)
1523                         continue;
1524
1525                 devices_info[i].dev = device;
1526                 devices_info[i].max_avail = avail_space;
1527
1528                 i++;
1529         }
1530
1531         nr_devices = i;
1532
1533         btrfs_descending_sort_devices(devices_info, nr_devices);
1534
1535         i = nr_devices - 1;
1536         avail_space = 0;
1537         while (nr_devices >= min_stripes) {
1538                 if (num_stripes > nr_devices)
1539                         num_stripes = nr_devices;
1540
1541                 if (devices_info[i].max_avail >= min_stripe_size) {
1542                         int j;
1543                         u64 alloc_size;
1544
1545                         avail_space += devices_info[i].max_avail * num_stripes;
1546                         alloc_size = devices_info[i].max_avail;
1547                         for (j = i + 1 - num_stripes; j <= i; j++)
1548                                 devices_info[j].max_avail -= alloc_size;
1549                 }
1550                 i--;
1551                 nr_devices--;
1552         }
1553
1554         kfree(devices_info);
1555         *free_bytes = avail_space;
1556         return 0;
1557 }
1558
1559 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1560 {
1561         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
1562         struct btrfs_super_block *disk_super = fs_info->super_copy;
1563         struct list_head *head = &fs_info->space_info;
1564         struct btrfs_space_info *found;
1565         u64 total_used = 0;
1566         u64 total_free_data = 0;
1567         int bits = dentry->d_sb->s_blocksize_bits;
1568         __be32 *fsid = (__be32 *)fs_info->fsid;
1569         int ret;
1570
1571         /* holding chunk_muext to avoid allocating new chunks */
1572         mutex_lock(&fs_info->chunk_mutex);
1573         rcu_read_lock();
1574         list_for_each_entry_rcu(found, head, list) {
1575                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
1576                         total_free_data += found->disk_total - found->disk_used;
1577                         total_free_data -=
1578                                 btrfs_account_ro_block_groups_free_space(found);
1579                 }
1580
1581                 total_used += found->disk_used;
1582         }
1583         rcu_read_unlock();
1584
1585         buf->f_namelen = BTRFS_NAME_LEN;
1586         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
1587         buf->f_bfree = buf->f_blocks - (total_used >> bits);
1588         buf->f_bsize = dentry->d_sb->s_blocksize;
1589         buf->f_type = BTRFS_SUPER_MAGIC;
1590         buf->f_bavail = total_free_data;
1591         ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
1592         if (ret) {
1593                 mutex_unlock(&fs_info->chunk_mutex);
1594                 return ret;
1595         }
1596         buf->f_bavail += total_free_data;
1597         buf->f_bavail = buf->f_bavail >> bits;
1598         mutex_unlock(&fs_info->chunk_mutex);
1599
1600         /* We treat it as constant endianness (it doesn't matter _which_)
1601            because we want the fsid to come out the same whether mounted
1602            on a big-endian or little-endian host */
1603         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
1604         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
1605         /* Mask in the root object ID too, to disambiguate subvols */
1606         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
1607         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
1608
1609         return 0;
1610 }
1611
1612 static void btrfs_kill_super(struct super_block *sb)
1613 {
1614         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1615         kill_anon_super(sb);
1616         free_fs_info(fs_info);
1617 }
1618
1619 static struct file_system_type btrfs_fs_type = {
1620         .owner          = THIS_MODULE,
1621         .name           = "btrfs",
1622         .mount          = btrfs_mount,
1623         .kill_sb        = btrfs_kill_super,
1624         .fs_flags       = FS_REQUIRES_DEV,
1625 };
1626 MODULE_ALIAS_FS("btrfs");
1627
1628 /*
1629  * used by btrfsctl to scan devices when no FS is mounted
1630  */
1631 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
1632                                 unsigned long arg)
1633 {
1634         struct btrfs_ioctl_vol_args *vol;
1635         struct btrfs_fs_devices *fs_devices;
1636         int ret = -ENOTTY;
1637
1638         if (!capable(CAP_SYS_ADMIN))
1639                 return -EPERM;
1640
1641         vol = memdup_user((void __user *)arg, sizeof(*vol));
1642         if (IS_ERR(vol))
1643                 return PTR_ERR(vol);
1644
1645         switch (cmd) {
1646         case BTRFS_IOC_SCAN_DEV:
1647                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1648                                             &btrfs_fs_type, &fs_devices);
1649                 break;
1650         case BTRFS_IOC_DEVICES_READY:
1651                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1652                                             &btrfs_fs_type, &fs_devices);
1653                 if (ret)
1654                         break;
1655                 ret = !(fs_devices->num_devices == fs_devices->total_devices);
1656                 break;
1657         }
1658
1659         kfree(vol);
1660         return ret;
1661 }
1662
1663 static int btrfs_freeze(struct super_block *sb)
1664 {
1665         struct btrfs_trans_handle *trans;
1666         struct btrfs_root *root = btrfs_sb(sb)->tree_root;
1667
1668         trans = btrfs_attach_transaction_barrier(root);
1669         if (IS_ERR(trans)) {
1670                 /* no transaction, don't bother */
1671                 if (PTR_ERR(trans) == -ENOENT)
1672                         return 0;
1673                 return PTR_ERR(trans);
1674         }
1675         return btrfs_commit_transaction(trans, root);
1676 }
1677
1678 static int btrfs_unfreeze(struct super_block *sb)
1679 {
1680         return 0;
1681 }
1682
1683 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
1684 {
1685         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
1686         struct btrfs_fs_devices *cur_devices;
1687         struct btrfs_device *dev, *first_dev = NULL;
1688         struct list_head *head;
1689         struct rcu_string *name;
1690
1691         mutex_lock(&fs_info->fs_devices->device_list_mutex);
1692         cur_devices = fs_info->fs_devices;
1693         while (cur_devices) {
1694                 head = &cur_devices->devices;
1695                 list_for_each_entry(dev, head, dev_list) {
1696                         if (dev->missing)
1697                                 continue;
1698                         if (!first_dev || dev->devid < first_dev->devid)
1699                                 first_dev = dev;
1700                 }
1701                 cur_devices = cur_devices->seed;
1702         }
1703
1704         if (first_dev) {
1705                 rcu_read_lock();
1706                 name = rcu_dereference(first_dev->name);
1707                 seq_escape(m, name->str, " \t\n\\");
1708                 rcu_read_unlock();
1709         } else {
1710                 WARN_ON(1);
1711         }
1712         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1713         return 0;
1714 }
1715
1716 static const struct super_operations btrfs_super_ops = {
1717         .drop_inode     = btrfs_drop_inode,
1718         .evict_inode    = btrfs_evict_inode,
1719         .put_super      = btrfs_put_super,
1720         .sync_fs        = btrfs_sync_fs,
1721         .show_options   = btrfs_show_options,
1722         .show_devname   = btrfs_show_devname,
1723         .write_inode    = btrfs_write_inode,
1724         .alloc_inode    = btrfs_alloc_inode,
1725         .destroy_inode  = btrfs_destroy_inode,
1726         .statfs         = btrfs_statfs,
1727         .remount_fs     = btrfs_remount,
1728         .freeze_fs      = btrfs_freeze,
1729         .unfreeze_fs    = btrfs_unfreeze,
1730 };
1731
1732 static const struct file_operations btrfs_ctl_fops = {
1733         .unlocked_ioctl  = btrfs_control_ioctl,
1734         .compat_ioctl = btrfs_control_ioctl,
1735         .owner   = THIS_MODULE,
1736         .llseek = noop_llseek,
1737 };
1738
1739 static struct miscdevice btrfs_misc = {
1740         .minor          = BTRFS_MINOR,
1741         .name           = "btrfs-control",
1742         .fops           = &btrfs_ctl_fops
1743 };
1744
1745 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
1746 MODULE_ALIAS("devname:btrfs-control");
1747
1748 static int btrfs_interface_init(void)
1749 {
1750         return misc_register(&btrfs_misc);
1751 }
1752
1753 static void btrfs_interface_exit(void)
1754 {
1755         if (misc_deregister(&btrfs_misc) < 0)
1756                 printk(KERN_INFO "btrfs: misc_deregister failed for control device\n");
1757 }
1758
1759 static void btrfs_print_info(void)
1760 {
1761         printk(KERN_INFO "Btrfs loaded"
1762 #ifdef CONFIG_BTRFS_DEBUG
1763                         ", debug=on"
1764 #endif
1765 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1766                         ", integrity-checker=on"
1767 #endif
1768                         "\n");
1769 }
1770
1771 static int btrfs_run_sanity_tests(void)
1772 {
1773         return btrfs_test_free_space_cache();
1774 }
1775
1776 static int __init init_btrfs_fs(void)
1777 {
1778         int err;
1779
1780         err = btrfs_init_sysfs();
1781         if (err)
1782                 return err;
1783
1784         btrfs_init_compress();
1785
1786         err = btrfs_init_cachep();
1787         if (err)
1788                 goto free_compress;
1789
1790         err = extent_io_init();
1791         if (err)
1792                 goto free_cachep;
1793
1794         err = extent_map_init();
1795         if (err)
1796                 goto free_extent_io;
1797
1798         err = ordered_data_init();
1799         if (err)
1800                 goto free_extent_map;
1801
1802         err = btrfs_delayed_inode_init();
1803         if (err)
1804                 goto free_ordered_data;
1805
1806         err = btrfs_auto_defrag_init();
1807         if (err)
1808                 goto free_delayed_inode;
1809
1810         err = btrfs_delayed_ref_init();
1811         if (err)
1812                 goto free_auto_defrag;
1813
1814         err = btrfs_prelim_ref_init();
1815         if (err)
1816                 goto free_prelim_ref;
1817
1818         err = btrfs_interface_init();
1819         if (err)
1820                 goto free_delayed_ref;
1821
1822         btrfs_init_lockdep();
1823
1824         btrfs_print_info();
1825
1826         err = btrfs_run_sanity_tests();
1827         if (err)
1828                 goto unregister_ioctl;
1829
1830         err = register_filesystem(&btrfs_fs_type);
1831         if (err)
1832                 goto unregister_ioctl;
1833
1834         return 0;
1835
1836 unregister_ioctl:
1837         btrfs_interface_exit();
1838 free_prelim_ref:
1839         btrfs_prelim_ref_exit();
1840 free_delayed_ref:
1841         btrfs_delayed_ref_exit();
1842 free_auto_defrag:
1843         btrfs_auto_defrag_exit();
1844 free_delayed_inode:
1845         btrfs_delayed_inode_exit();
1846 free_ordered_data:
1847         ordered_data_exit();
1848 free_extent_map:
1849         extent_map_exit();
1850 free_extent_io:
1851         extent_io_exit();
1852 free_cachep:
1853         btrfs_destroy_cachep();
1854 free_compress:
1855         btrfs_exit_compress();
1856         btrfs_exit_sysfs();
1857         return err;
1858 }
1859
1860 static void __exit exit_btrfs_fs(void)
1861 {
1862         btrfs_destroy_cachep();
1863         btrfs_delayed_ref_exit();
1864         btrfs_auto_defrag_exit();
1865         btrfs_delayed_inode_exit();
1866         btrfs_prelim_ref_exit();
1867         ordered_data_exit();
1868         extent_map_exit();
1869         extent_io_exit();
1870         btrfs_interface_exit();
1871         unregister_filesystem(&btrfs_fs_type);
1872         btrfs_exit_sysfs();
1873         btrfs_cleanup_fs_uuids();
1874         btrfs_exit_compress();
1875 }
1876
1877 module_init(init_btrfs_fs)
1878 module_exit(exit_btrfs_fs)
1879
1880 MODULE_LICENSE("GPL");