fs/btrfs/super.c

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