fs/btrfs/super.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/blkdev.h>
   7 #include <linux/module.h>
   8 #include <linux/fs.h>
   9 #include <linux/pagemap.h>
  10 #include <linux/highmem.h>
  11 #include <linux/time.h>
  12 #include <linux/init.h>
  13 #include <linux/seq_file.h>
  14 #include <linux/string.h>
  15 #include <linux/backing-dev.h>
  16 #include <linux/mount.h>
  17 #include <linux/writeback.h>
  18 #include <linux/statfs.h>
  19 #include <linux/compat.h>
  20 #include <linux/parser.h>
  21 #include <linux/ctype.h>
  22 #include <linux/namei.h>
  23 #include <linux/miscdevice.h>
  24 #include <linux/magic.h>
  25 #include <linux/slab.h>
  26 #include <linux/cleancache.h>
  27 #include <linux/ratelimit.h>
  28 #include <linux/crc32c.h>
  29 #include <linux/btrfs.h>
  30 #include "delayed-inode.h"
  31 #include "ctree.h"
  32 #include "disk-io.h"
  33 #include "transaction.h"
  34 #include "btrfs_inode.h"
  35 #include "print-tree.h"
  36 #include "props.h"
  37 #include "xattr.h"
  38 #include "volumes.h"
  39 #include "export.h"
  40 #include "compression.h"
  41 #include "rcu-string.h"
  42 #include "dev-replace.h"
  43 #include "free-space-cache.h"
  44 #include "backref.h"
  45 #include "space-info.h"
  46 #include "sysfs.h"
  47 #include "tests/btrfs-tests.h"
  48 #include "block-group.h"
  49 #include "discard.h"
  50
  51 #include "qgroup.h"
  52 #define CREATE_TRACE_POINTS
  53 #include <trace/events/btrfs.h>
  54
  55 static const struct super_operations btrfs_super_ops;
  56
  57 /*
  58  * Types for mounting the default subvolume and a subvolume explicitly
  59  * requested by subvol=/path. That way the callchain is straightforward and we
  60  * don't have to play tricks with the mount options and recursive calls to
  61  * btrfs_mount.
  62  *
  63  * The new btrfs_root_fs_type also servers as a tag for the bdev_holder.
  64  */
  65 static struct file_system_type btrfs_fs_type;
  66 static struct file_system_type btrfs_root_fs_type;
  67
  68 static int btrfs_remount(struct super_block *sb, int *flags, char *data);
  69
  70 /*
  71  * Generally the error codes correspond to their respective errors, but there
  72  * are a few special cases.
  73  *
  74  * EUCLEAN: Any sort of corruption that we encounter.  The tree-checker for
  75  *          instance will return EUCLEAN if any of the blocks are corrupted in
  76  *          a way that is problematic.  We want to reserve EUCLEAN for these
  77  *          sort of corruptions.
  78  *
  79  * EROFS: If we check BTRFS_FS_STATE_ERROR and fail out with a return error, we
  80  *        need to use EROFS for this case.  We will have no idea of the
  81  *        original failure, that will have been reported at the time we tripped
  82  *        over the error.  Each subsequent error that doesn't have any context
  83  *        of the original error should use EROFS when handling BTRFS_FS_STATE_ERROR.
  84  */
  85 const char * __attribute_const__ btrfs_decode_error(int errno)
  86 {
  87         char *errstr = "unknown";
  88
  89         switch (errno) {
  90         case -ENOENT:           /* -2 */
  91                 errstr = "No such entry";
  92                 break;
  93         case -EIO:              /* -5 */
  94                 errstr = "IO failure";
  95                 break;
  96         case -ENOMEM:           /* -12*/
  97                 errstr = "Out of memory";
  98                 break;
  99         case -EEXIST:           /* -17 */
 100                 errstr = "Object already exists";
 101                 break;
 102         case -ENOSPC:           /* -28 */
 103                 errstr = "No space left";
 104                 break;
 105         case -EROFS:            /* -30 */
 106                 errstr = "Readonly filesystem";
 107                 break;
 108         case -EOPNOTSUPP:       /* -95 */
 109                 errstr = "Operation not supported";
 110                 break;
 111         case -EUCLEAN:          /* -117 */
 112                 errstr = "Filesystem corrupted";
 113                 break;
 114         case -EDQUOT:           /* -122 */
 115                 errstr = "Quota exceeded";
 116                 break;
 117         }
 118
 119         return errstr;
 120 }
 121
 122 /*
 123  * __btrfs_handle_fs_error decodes expected errors from the caller and
 124  * invokes the appropriate error response.
 125  */
 126 __cold
 127 void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function,
 128                        unsigned int line, int errno, const char *fmt, ...)
 129 {
 130         struct super_block *sb = fs_info->sb;
 131 #ifdef CONFIG_PRINTK
 132         const char *errstr;
 133 #endif
 134
 135         /*
 136          * Special case: if the error is EROFS, and we're already
 137          * under SB_RDONLY, then it is safe here.
 138          */
 139         if (errno == -EROFS && sb_rdonly(sb))
 140                 return;
 141
 142 #ifdef CONFIG_PRINTK
 143         errstr = btrfs_decode_error(errno);
 144         if (fmt) {
 145                 struct va_format vaf;
 146                 va_list args;
 147
 148                 va_start(args, fmt);
 149                 vaf.fmt = fmt;
 150                 vaf.va = &args;
 151
 152                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s (%pV)\n",
 153                         sb->s_id, function, line, errno, errstr, &vaf);
 154                 va_end(args);
 155         } else {
 156                 pr_crit("BTRFS: error (device %s) in %s:%d: errno=%d %s\n",
 157                         sb->s_id, function, line, errno, errstr);
 158         }
 159 #endif
 160
 161         /*
 162          * Today we only save the error info to memory.  Long term we'll
 163          * also send it down to the disk
 164          */
 165         set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
 166
 167         /* Don't go through full error handling during mount */
 168         if (!(sb->s_flags & SB_BORN))
 169                 return;
 170
 171         if (sb_rdonly(sb))
 172                 return;
 173
 174         btrfs_discard_stop(fs_info);
 175
 176         /* btrfs handle error by forcing the filesystem readonly */
 177         sb->s_flags |= SB_RDONLY;
 178         btrfs_info(fs_info, "forced readonly");
 179         /*
 180          * Note that a running device replace operation is not canceled here
 181          * although there is no way to update the progress. It would add the
 182          * risk of a deadlock, therefore the canceling is omitted. The only
 183          * penalty is that some I/O remains active until the procedure
 184          * completes. The next time when the filesystem is mounted writable
 185          * again, the device replace operation continues.
 186          */
 187 }
 188
 189 #ifdef CONFIG_PRINTK
 190 static const char * const logtypes[] = {
 191         "emergency",
 192         "alert",
 193         "critical",
 194         "error",
 195         "warning",
 196         "notice",
 197         "info",
 198         "debug",
 199 };
 200
 201
 202 /*
 203  * Use one ratelimit state per log level so that a flood of less important
 204  * messages doesn't cause more important ones to be dropped.
 205  */
 206 static struct ratelimit_state printk_limits[] = {
 207         RATELIMIT_STATE_INIT(printk_limits[0], DEFAULT_RATELIMIT_INTERVAL, 100),
 208         RATELIMIT_STATE_INIT(printk_limits[1], DEFAULT_RATELIMIT_INTERVAL, 100),
 209         RATELIMIT_STATE_INIT(printk_limits[2], DEFAULT_RATELIMIT_INTERVAL, 100),
 210         RATELIMIT_STATE_INIT(printk_limits[3], DEFAULT_RATELIMIT_INTERVAL, 100),
 211         RATELIMIT_STATE_INIT(printk_limits[4], DEFAULT_RATELIMIT_INTERVAL, 100),
 212         RATELIMIT_STATE_INIT(printk_limits[5], DEFAULT_RATELIMIT_INTERVAL, 100),
 213         RATELIMIT_STATE_INIT(printk_limits[6], DEFAULT_RATELIMIT_INTERVAL, 100),
 214         RATELIMIT_STATE_INIT(printk_limits[7], DEFAULT_RATELIMIT_INTERVAL, 100),
 215 };
 216
 217 void __cold btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 218 {
 219         char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1] = "\0";
 220         struct va_format vaf;
 221         va_list args;
 222         int kern_level;
 223         const char *type = logtypes[4];
 224         struct ratelimit_state *ratelimit = &printk_limits[4];
 225
 226         va_start(args, fmt);
 227
 228         while ((kern_level = printk_get_level(fmt)) != 0) {
 229                 size_t size = printk_skip_level(fmt) - fmt;
 230
 231                 if (kern_level >= '0' && kern_level <= '7') {
 232                         memcpy(lvl, fmt,  size);
 233                         lvl[size] = '\0';
 234                         type = logtypes[kern_level - '0'];
 235                         ratelimit = &printk_limits[kern_level - '0'];
 236                 }
 237                 fmt += size;
 238         }
 239
 240         vaf.fmt = fmt;
 241         vaf.va = &args;
 242
 243         if (__ratelimit(ratelimit))
 244                 printk("%sBTRFS %s (device %s): %pV\n", lvl, type,
 245                         fs_info ? fs_info->sb->s_id : "<unknown>", &vaf);
 246
 247         va_end(args);
 248 }
 249 #endif
 250
 251 /*
 252  * We only mark the transaction aborted and then set the file system read-only.
 253  * This will prevent new transactions from starting or trying to join this
 254  * one.
 255  *
 256  * This means that error recovery at the call site is limited to freeing
 257  * any local memory allocations and passing the error code up without
 258  * further cleanup. The transaction should complete as it normally would
 259  * in the call path but will return -EIO.
 260  *
 261  * We'll complete the cleanup in btrfs_end_transaction and
 262  * btrfs_commit_transaction.
 263  */
 264 __cold
 265 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 266                                const char *function,
 267                                unsigned int line, int errno)
 268 {
 269         struct btrfs_fs_info *fs_info = trans->fs_info;
 270
 271         WRITE_ONCE(trans->aborted, errno);
 272         /* Nothing used. The other threads that have joined this
 273          * transaction may be able to continue. */
 274         if (!trans->dirty && list_empty(&trans->new_bgs)) {
 275                 const char *errstr;
 276
 277                 errstr = btrfs_decode_error(errno);
 278                 btrfs_warn(fs_info,
 279                            "%s:%d: Aborting unused transaction(%s).",
 280                            function, line, errstr);
 281                 return;
 282         }
 283         WRITE_ONCE(trans->transaction->aborted, errno);
 284         /* Wake up anybody who may be waiting on this transaction */
 285         wake_up(&fs_info->transaction_wait);
 286         wake_up(&fs_info->transaction_blocked_wait);
 287         __btrfs_handle_fs_error(fs_info, function, line, errno, NULL);
 288 }
 289 /*
 290  * __btrfs_panic decodes unexpected, fatal errors from the caller,
 291  * issues an alert, and either panics or BUGs, depending on mount options.
 292  */
 293 __cold
 294 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 295                    unsigned int line, int errno, const char *fmt, ...)
 296 {
 297         char *s_id = "<unknown>";
 298         const char *errstr;
 299         struct va_format vaf = { .fmt = fmt };
 300         va_list args;
 301
 302         if (fs_info)
 303                 s_id = fs_info->sb->s_id;
 304
 305         va_start(args, fmt);
 306         vaf.va = &args;
 307
 308         errstr = btrfs_decode_error(errno);
 309         if (fs_info && (btrfs_test_opt(fs_info, PANIC_ON_FATAL_ERROR)))
 310                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
 311                         s_id, function, line, &vaf, errno, errstr);
 312
 313         btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
 314                    function, line, &vaf, errno, errstr);
 315         va_end(args);
 316         /* Caller calls BUG() */
 317 }
 318
 319 static void btrfs_put_super(struct super_block *sb)
 320 {
 321         close_ctree(btrfs_sb(sb));
 322 }
 323
 324 enum {
 325         Opt_acl, Opt_noacl,
 326         Opt_clear_cache,
 327         Opt_commit_interval,
 328         Opt_compress,
 329         Opt_compress_force,
 330         Opt_compress_force_type,
 331         Opt_compress_type,
 332         Opt_degraded,
 333         Opt_device,
 334         Opt_fatal_errors,
 335         Opt_flushoncommit, Opt_noflushoncommit,
 336         Opt_inode_cache, Opt_noinode_cache,
 337         Opt_max_inline,
 338         Opt_barrier, Opt_nobarrier,
 339         Opt_datacow, Opt_nodatacow,
 340         Opt_datasum, Opt_nodatasum,
 341         Opt_defrag, Opt_nodefrag,
 342         Opt_discard, Opt_nodiscard,
 343         Opt_discard_mode,
 344         Opt_norecovery,
 345         Opt_ratio,
 346         Opt_rescan_uuid_tree,
 347         Opt_skip_balance,
 348         Opt_space_cache, Opt_no_space_cache,
 349         Opt_space_cache_version,
 350         Opt_ssd, Opt_nossd,
 351         Opt_ssd_spread, Opt_nossd_spread,
 352         Opt_subvol,
 353         Opt_subvol_empty,
 354         Opt_subvolid,
 355         Opt_thread_pool,
 356         Opt_treelog, Opt_notreelog,
 357         Opt_user_subvol_rm_allowed,
 358
 359         /* Rescue options */
 360         Opt_rescue,
 361         Opt_usebackuproot,
 362         Opt_nologreplay,
 363
 364         /* Deprecated options */
 365         Opt_recovery,
 366
 367         /* Debugging options */
 368         Opt_check_integrity,
 369         Opt_check_integrity_including_extent_data,
 370         Opt_check_integrity_print_mask,
 371         Opt_enospc_debug, Opt_noenospc_debug,
 372 #ifdef CONFIG_BTRFS_DEBUG
 373         Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 374 #endif
 375 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 376         Opt_ref_verify,
 377 #endif
 378         Opt_err,
 379 };
 380
 381 static const match_table_t tokens = {
 382         {Opt_acl, "acl"},
 383         {Opt_noacl, "noacl"},
 384         {Opt_clear_cache, "clear_cache"},
 385         {Opt_commit_interval, "commit=%u"},
 386         {Opt_compress, "compress"},
 387         {Opt_compress_type, "compress=%s"},
 388         {Opt_compress_force, "compress-force"},
 389         {Opt_compress_force_type, "compress-force=%s"},
 390         {Opt_degraded, "degraded"},
 391         {Opt_device, "device=%s"},
 392         {Opt_fatal_errors, "fatal_errors=%s"},
 393         {Opt_flushoncommit, "flushoncommit"},
 394         {Opt_noflushoncommit, "noflushoncommit"},
 395         {Opt_inode_cache, "inode_cache"},
 396         {Opt_noinode_cache, "noinode_cache"},
 397         {Opt_max_inline, "max_inline=%s"},
 398         {Opt_barrier, "barrier"},
 399         {Opt_nobarrier, "nobarrier"},
 400         {Opt_datacow, "datacow"},
 401         {Opt_nodatacow, "nodatacow"},
 402         {Opt_datasum, "datasum"},
 403         {Opt_nodatasum, "nodatasum"},
 404         {Opt_defrag, "autodefrag"},
 405         {Opt_nodefrag, "noautodefrag"},
 406         {Opt_discard, "discard"},
 407         {Opt_discard_mode, "discard=%s"},
 408         {Opt_nodiscard, "nodiscard"},
 409         {Opt_norecovery, "norecovery"},
 410         {Opt_ratio, "metadata_ratio=%u"},
 411         {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
 412         {Opt_skip_balance, "skip_balance"},
 413         {Opt_space_cache, "space_cache"},
 414         {Opt_no_space_cache, "nospace_cache"},
 415         {Opt_space_cache_version, "space_cache=%s"},
 416         {Opt_ssd, "ssd"},
 417         {Opt_nossd, "nossd"},
 418         {Opt_ssd_spread, "ssd_spread"},
 419         {Opt_nossd_spread, "nossd_spread"},
 420         {Opt_subvol, "subvol=%s"},
 421         {Opt_subvol_empty, "subvol="},
 422         {Opt_subvolid, "subvolid=%s"},
 423         {Opt_thread_pool, "thread_pool=%u"},
 424         {Opt_treelog, "treelog"},
 425         {Opt_notreelog, "notreelog"},
 426         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 427
 428         /* Rescue options */
 429         {Opt_rescue, "rescue=%s"},
 430         /* Deprecated, with alias rescue=nologreplay */
 431         {Opt_nologreplay, "nologreplay"},
 432         /* Deprecated, with alias rescue=usebackuproot */
 433         {Opt_usebackuproot, "usebackuproot"},
 434
 435         /* Deprecated options */
 436         {Opt_recovery, "recovery"},
 437
 438         /* Debugging options */
 439         {Opt_check_integrity, "check_int"},
 440         {Opt_check_integrity_including_extent_data, "check_int_data"},
 441         {Opt_check_integrity_print_mask, "check_int_print_mask=%u"},
 442         {Opt_enospc_debug, "enospc_debug"},
 443         {Opt_noenospc_debug, "noenospc_debug"},
 444 #ifdef CONFIG_BTRFS_DEBUG
 445         {Opt_fragment_data, "fragment=data"},
 446         {Opt_fragment_metadata, "fragment=metadata"},
 447         {Opt_fragment_all, "fragment=all"},
 448 #endif
 449 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 450         {Opt_ref_verify, "ref_verify"},
 451 #endif
 452         {Opt_err, NULL},
 453 };
 454
 455 static const match_table_t rescue_tokens = {
 456         {Opt_usebackuproot, "usebackuproot"},
 457         {Opt_nologreplay, "nologreplay"},
 458         {Opt_err, NULL},
 459 };
 460
 461 static int parse_rescue_options(struct btrfs_fs_info *info, const char *options)
 462 {
 463         char *opts;
 464         char *orig;
 465         char *p;
 466         substring_t args[MAX_OPT_ARGS];
 467         int ret = 0;
 468
 469         opts = kstrdup(options, GFP_KERNEL);
 470         if (!opts)
 471                 return -ENOMEM;
 472         orig = opts;
 473
 474         while ((p = strsep(&opts, ":")) != NULL) {
 475                 int token;
 476
 477                 if (!*p)
 478                         continue;
 479                 token = match_token(p, rescue_tokens, args);
 480                 switch (token){
 481                 case Opt_usebackuproot:
 482                         btrfs_info(info,
 483                                    "trying to use backup root at mount time");
 484                         btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
 485                         break;
 486                 case Opt_nologreplay:
 487                         btrfs_set_and_info(info, NOLOGREPLAY,
 488                                            "disabling log replay at mount time");
 489                         break;
 490                 case Opt_err:
 491                         btrfs_info(info, "unrecognized rescue option '%s'", p);
 492                         ret = -EINVAL;
 493                         goto out;
 494                 default:
 495                         break;
 496                 }
 497
 498         }
 499 out:
 500         kfree(orig);
 501         return ret;
 502 }
 503
 504 /*
 505  * Regular mount options parser.  Everything that is needed only when
 506  * reading in a new superblock is parsed here.
 507  * XXX JDM: This needs to be cleaned up for remount.
 508  */
 509 int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 510                         unsigned long new_flags)
 511 {
 512         substring_t args[MAX_OPT_ARGS];
 513         char *p, *num;
 514         u64 cache_gen;
 515         int intarg;
 516         int ret = 0;
 517         char *compress_type;
 518         bool compress_force = false;
 519         enum btrfs_compression_type saved_compress_type;
 520         int saved_compress_level;
 521         bool saved_compress_force;
 522         int no_compress = 0;
 523
 524         cache_gen = btrfs_super_cache_generation(info->super_copy);
 525         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
 526                 btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
 527         else if (cache_gen)
 528                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 529
 530         /*
 531          * Even the options are empty, we still need to do extra check
 532          * against new flags
 533          */
 534         if (!options)
 535                 goto check;
 536
 537         while ((p = strsep(&options, ",")) != NULL) {
 538                 int token;
 539                 if (!*p)
 540                         continue;
 541
 542                 token = match_token(p, tokens, args);
 543                 switch (token) {
 544                 case Opt_degraded:
 545                         btrfs_info(info, "allowing degraded mounts");
 546                         btrfs_set_opt(info->mount_opt, DEGRADED);
 547                         break;
 548                 case Opt_subvol:
 549                 case Opt_subvol_empty:
 550                 case Opt_subvolid:
 551                 case Opt_device:
 552                         /*
 553                          * These are parsed by btrfs_parse_subvol_options or
 554                          * btrfs_parse_device_options and can be ignored here.
 555                          */
 556                         break;
 557                 case Opt_nodatasum:
 558                         btrfs_set_and_info(info, NODATASUM,
 559                                            "setting nodatasum");
 560                         break;
 561                 case Opt_datasum:
 562                         if (btrfs_test_opt(info, NODATASUM)) {
 563                                 if (btrfs_test_opt(info, NODATACOW))
 564                                         btrfs_info(info,
 565                                                    "setting datasum, datacow enabled");
 566                                 else
 567                                         btrfs_info(info, "setting datasum");
 568                         }
 569                         btrfs_clear_opt(info->mount_opt, NODATACOW);
 570                         btrfs_clear_opt(info->mount_opt, NODATASUM);
 571                         break;
 572                 case Opt_nodatacow:
 573                         if (!btrfs_test_opt(info, NODATACOW)) {
 574                                 if (!btrfs_test_opt(info, COMPRESS) ||
 575                                     !btrfs_test_opt(info, FORCE_COMPRESS)) {
 576                                         btrfs_info(info,
 577                                                    "setting nodatacow, compression disabled");
 578                                 } else {
 579                                         btrfs_info(info, "setting nodatacow");
 580                                 }
 581                         }
 582                         btrfs_clear_opt(info->mount_opt, COMPRESS);
 583                         btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 584                         btrfs_set_opt(info->mount_opt, NODATACOW);
 585                         btrfs_set_opt(info->mount_opt, NODATASUM);
 586                         break;
 587                 case Opt_datacow:
 588                         btrfs_clear_and_info(info, NODATACOW,
 589                                              "setting datacow");
 590                         break;
 591                 case Opt_compress_force:
 592                 case Opt_compress_force_type:
 593                         compress_force = true;
 594                         fallthrough;
 595                 case Opt_compress:
 596                 case Opt_compress_type:
 597                         saved_compress_type = btrfs_test_opt(info,
 598                                                              COMPRESS) ?
 599                                 info->compress_type : BTRFS_COMPRESS_NONE;
 600                         saved_compress_force =
 601                                 btrfs_test_opt(info, FORCE_COMPRESS);
 602                         saved_compress_level = info->compress_level;
 603                         if (token == Opt_compress ||
 604                             token == Opt_compress_force ||
 605                             strncmp(args[0].from, "zlib", 4) == 0) {
 606                                 compress_type = "zlib";
 607
 608                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 609                                 info->compress_level = BTRFS_ZLIB_DEFAULT_LEVEL;
 610                                 /*
 611                                  * args[0] contains uninitialized data since
 612                                  * for these tokens we don't expect any
 613                                  * parameter.
 614                                  */
 615                                 if (token != Opt_compress &&
 616                                     token != Opt_compress_force)
 617                                         info->compress_level =
 618                                           btrfs_compress_str2level(
 619                                                         BTRFS_COMPRESS_ZLIB,
 620                                                         args[0].from + 4);
 621                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 622                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 623                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 624                                 no_compress = 0;
 625                         } else if (strncmp(args[0].from, "lzo", 3) == 0) {
 626                                 compress_type = "lzo";
 627                                 info->compress_type = BTRFS_COMPRESS_LZO;
 628                                 info->compress_level = 0;
 629                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 630                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 631                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 632                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
 633                                 no_compress = 0;
 634                         } else if (strncmp(args[0].from, "zstd", 4) == 0) {
 635                                 compress_type = "zstd";
 636                                 info->compress_type = BTRFS_COMPRESS_ZSTD;
 637                                 info->compress_level =
 638                                         btrfs_compress_str2level(
 639                                                          BTRFS_COMPRESS_ZSTD,
 640                                                          args[0].from + 4);
 641                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 642                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 643                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 644                                 btrfs_set_fs_incompat(info, COMPRESS_ZSTD);
 645                                 no_compress = 0;
 646                         } else if (strncmp(args[0].from, "no", 2) == 0) {
 647                                 compress_type = "no";
 648                                 info->compress_level = 0;
 649                                 info->compress_type = 0;
 650                                 btrfs_clear_opt(info->mount_opt, COMPRESS);
 651                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 652                                 compress_force = false;
 653                                 no_compress++;
 654                         } else {
 655                                 btrfs_err(info, "unrecognized compression value %s",
 656                                           args[0].from);
 657                                 ret = -EINVAL;
 658                                 goto out;
 659                         }
 660
 661                         if (compress_force) {
 662                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 663                         } else {
 664                                 /*
 665                                  * If we remount from compress-force=xxx to
 666                                  * compress=xxx, we need clear FORCE_COMPRESS
 667                                  * flag, otherwise, there is no way for users
 668                                  * to disable forcible compression separately.
 669                                  */
 670                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 671                         }
 672                         if (no_compress == 1) {
 673                                 btrfs_info(info, "use no compression");
 674                         } else if ((info->compress_type != saved_compress_type) ||
 675                                    (compress_force != saved_compress_force) ||
 676                                    (info->compress_level != saved_compress_level)) {
 677                                 btrfs_info(info, "%s %s compression, level %d",
 678                                            (compress_force) ? "force" : "use",
 679                                            compress_type, info->compress_level);
 680                         }
 681                         compress_force = false;
 682                         break;
 683                 case Opt_ssd:
 684                         btrfs_set_and_info(info, SSD,
 685                                            "enabling ssd optimizations");
 686                         btrfs_clear_opt(info->mount_opt, NOSSD);
 687                         break;
 688                 case Opt_ssd_spread:
 689                         btrfs_set_and_info(info, SSD,
 690                                            "enabling ssd optimizations");
 691                         btrfs_set_and_info(info, SSD_SPREAD,
 692                                            "using spread ssd allocation scheme");
 693                         btrfs_clear_opt(info->mount_opt, NOSSD);
 694                         break;
 695                 case Opt_nossd:
 696                         btrfs_set_opt(info->mount_opt, NOSSD);
 697                         btrfs_clear_and_info(info, SSD,
 698                                              "not using ssd optimizations");
 699                         fallthrough;
 700                 case Opt_nossd_spread:
 701                         btrfs_clear_and_info(info, SSD_SPREAD,
 702                                              "not using spread ssd allocation scheme");
 703                         break;
 704                 case Opt_barrier:
 705                         btrfs_clear_and_info(info, NOBARRIER,
 706                                              "turning on barriers");
 707                         break;
 708                 case Opt_nobarrier:
 709                         btrfs_set_and_info(info, NOBARRIER,
 710                                            "turning off barriers");
 711                         break;
 712                 case Opt_thread_pool:
 713                         ret = match_int(&args[0], &intarg);
 714                         if (ret) {
 715                                 btrfs_err(info, "unrecognized thread_pool value %s",
 716                                           args[0].from);
 717                                 goto out;
 718                         } else if (intarg == 0) {
 719                                 btrfs_err(info, "invalid value 0 for thread_pool");
 720                                 ret = -EINVAL;
 721                                 goto out;
 722                         }
 723                         info->thread_pool_size = intarg;
 724                         break;
 725                 case Opt_max_inline:
 726                         num = match_strdup(&args[0]);
 727                         if (num) {
 728                                 info->max_inline = memparse(num, NULL);
 729                                 kfree(num);
 730
 731                                 if (info->max_inline) {
 732                                         info->max_inline = min_t(u64,
 733                                                 info->max_inline,
 734                                                 info->sectorsize);
 735                                 }
 736                                 btrfs_info(info, "max_inline at %llu",
 737                                            info->max_inline);
 738                         } else {
 739                                 ret = -ENOMEM;
 740                                 goto out;
 741                         }
 742                         break;
 743                 case Opt_acl:
 744 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 745                         info->sb->s_flags |= SB_POSIXACL;
 746                         break;
 747 #else
 748                         btrfs_err(info, "support for ACL not compiled in!");
 749                         ret = -EINVAL;
 750                         goto out;
 751 #endif
 752                 case Opt_noacl:
 753                         info->sb->s_flags &= ~SB_POSIXACL;
 754                         break;
 755                 case Opt_notreelog:
 756                         btrfs_set_and_info(info, NOTREELOG,
 757                                            "disabling tree log");
 758                         break;
 759                 case Opt_treelog:
 760                         btrfs_clear_and_info(info, NOTREELOG,
 761                                              "enabling tree log");
 762                         break;
 763                 case Opt_norecovery:
 764                 case Opt_nologreplay:
 765                         btrfs_warn(info,
 766                 "'nologreplay' is deprecated, use 'rescue=nologreplay' instead");
 767                         btrfs_set_and_info(info, NOLOGREPLAY,
 768                                            "disabling log replay at mount time");
 769                         break;
 770                 case Opt_flushoncommit:
 771                         btrfs_set_and_info(info, FLUSHONCOMMIT,
 772                                            "turning on flush-on-commit");
 773                         break;
 774                 case Opt_noflushoncommit:
 775                         btrfs_clear_and_info(info, FLUSHONCOMMIT,
 776                                              "turning off flush-on-commit");
 777                         break;
 778                 case Opt_ratio:
 779                         ret = match_int(&args[0], &intarg);
 780                         if (ret) {
 781                                 btrfs_err(info, "unrecognized metadata_ratio value %s",
 782                                           args[0].from);
 783                                 goto out;
 784                         }
 785                         info->metadata_ratio = intarg;
 786                         btrfs_info(info, "metadata ratio %u",
 787                                    info->metadata_ratio);
 788                         break;
 789                 case Opt_discard:
 790                 case Opt_discard_mode:
 791                         if (token == Opt_discard ||
 792                             strcmp(args[0].from, "sync") == 0) {
 793                                 btrfs_clear_opt(info->mount_opt, DISCARD_ASYNC);
 794                                 btrfs_set_and_info(info, DISCARD_SYNC,
 795                                                    "turning on sync discard");
 796                         } else if (strcmp(args[0].from, "async") == 0) {
 797                                 btrfs_clear_opt(info->mount_opt, DISCARD_SYNC);
 798                                 btrfs_set_and_info(info, DISCARD_ASYNC,
 799                                                    "turning on async discard");
 800                         } else {
 801                                 btrfs_err(info, "unrecognized discard mode value %s",
 802                                           args[0].from);
 803                                 ret = -EINVAL;
 804                                 goto out;
 805                         }
 806                         break;
 807                 case Opt_nodiscard:
 808                         btrfs_clear_and_info(info, DISCARD_SYNC,
 809                                              "turning off discard");
 810                         btrfs_clear_and_info(info, DISCARD_ASYNC,
 811                                              "turning off async discard");
 812                         break;
 813                 case Opt_space_cache:
 814                 case Opt_space_cache_version:
 815                         if (token == Opt_space_cache ||
 816                             strcmp(args[0].from, "v1") == 0) {
 817                                 btrfs_clear_opt(info->mount_opt,
 818                                                 FREE_SPACE_TREE);
 819                                 btrfs_set_and_info(info, SPACE_CACHE,
 820                                            "enabling disk space caching");
 821                         } else if (strcmp(args[0].from, "v2") == 0) {
 822                                 btrfs_clear_opt(info->mount_opt,
 823                                                 SPACE_CACHE);
 824                                 btrfs_set_and_info(info, FREE_SPACE_TREE,
 825                                                    "enabling free space tree");
 826                         } else {
 827                                 btrfs_err(info, "unrecognized space_cache value %s",
 828                                           args[0].from);
 829                                 ret = -EINVAL;
 830                                 goto out;
 831                         }
 832                         break;
 833                 case Opt_rescan_uuid_tree:
 834                         btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
 835                         break;
 836                 case Opt_no_space_cache:
 837                         if (btrfs_test_opt(info, SPACE_CACHE)) {
 838                                 btrfs_clear_and_info(info, SPACE_CACHE,
 839                                              "disabling disk space caching");
 840                         }
 841                         if (btrfs_test_opt(info, FREE_SPACE_TREE)) {
 842                                 btrfs_clear_and_info(info, FREE_SPACE_TREE,
 843                                              "disabling free space tree");
 844                         }
 845                         break;
 846                 case Opt_inode_cache:
 847                         btrfs_warn(info,
 848         "the 'inode_cache' option is deprecated and will have no effect from 5.11");
 849                         btrfs_set_pending_and_info(info, INODE_MAP_CACHE,
 850                                            "enabling inode map caching");
 851                         break;
 852                 case Opt_noinode_cache:
 853                         btrfs_clear_pending_and_info(info, INODE_MAP_CACHE,
 854                                              "disabling inode map caching");
 855                         break;
 856                 case Opt_clear_cache:
 857                         btrfs_set_and_info(info, CLEAR_CACHE,
 858                                            "force clearing of disk cache");
 859                         break;
 860                 case Opt_user_subvol_rm_allowed:
 861                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 862                         break;
 863                 case Opt_enospc_debug:
 864                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 865                         break;
 866                 case Opt_noenospc_debug:
 867                         btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
 868                         break;
 869                 case Opt_defrag:
 870                         btrfs_set_and_info(info, AUTO_DEFRAG,
 871                                            "enabling auto defrag");
 872                         break;
 873                 case Opt_nodefrag:
 874                         btrfs_clear_and_info(info, AUTO_DEFRAG,
 875                                              "disabling auto defrag");
 876                         break;
 877                 case Opt_recovery:
 878                 case Opt_usebackuproot:
 879                         btrfs_warn(info,
 880                         "'%s' is deprecated, use 'rescue=usebackuproot' instead",
 881                                    token == Opt_recovery ? "recovery" :
 882                                    "usebackuproot");
 883                         btrfs_info(info,
 884                                    "trying to use backup root at mount time");
 885                         btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
 886                         break;
 887                 case Opt_skip_balance:
 888                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 889                         break;
 890 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 891                 case Opt_check_integrity_including_extent_data:
 892                         btrfs_info(info,
 893                                    "enabling check integrity including extent data");
 894                         btrfs_set_opt(info->mount_opt,
 895                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 896                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 897                         break;
 898                 case Opt_check_integrity:
 899                         btrfs_info(info, "enabling check integrity");
 900                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 901                         break;
 902                 case Opt_check_integrity_print_mask:
 903                         ret = match_int(&args[0], &intarg);
 904                         if (ret) {
 905                                 btrfs_err(info,
 906                                 "unrecognized check_integrity_print_mask value %s",
 907                                         args[0].from);
 908                                 goto out;
 909                         }
 910                         info->check_integrity_print_mask = intarg;
 911                         btrfs_info(info, "check_integrity_print_mask 0x%x",
 912                                    info->check_integrity_print_mask);
 913                         break;
 914 #else
 915                 case Opt_check_integrity_including_extent_data:
 916                 case Opt_check_integrity:
 917                 case Opt_check_integrity_print_mask:
 918                         btrfs_err(info,
 919                                   "support for check_integrity* not compiled in!");
 920                         ret = -EINVAL;
 921                         goto out;
 922 #endif
 923                 case Opt_fatal_errors:
 924                         if (strcmp(args[0].from, "panic") == 0) {
 925                                 btrfs_set_opt(info->mount_opt,
 926                                               PANIC_ON_FATAL_ERROR);
 927                         } else if (strcmp(args[0].from, "bug") == 0) {
 928                                 btrfs_clear_opt(info->mount_opt,
 929                                               PANIC_ON_FATAL_ERROR);
 930                         } else {
 931                                 btrfs_err(info, "unrecognized fatal_errors value %s",
 932                                           args[0].from);
 933                                 ret = -EINVAL;
 934                                 goto out;
 935                         }
 936                         break;
 937                 case Opt_commit_interval:
 938                         intarg = 0;
 939                         ret = match_int(&args[0], &intarg);
 940                         if (ret) {
 941                                 btrfs_err(info, "unrecognized commit_interval value %s",
 942                                           args[0].from);
 943                                 ret = -EINVAL;
 944                                 goto out;
 945                         }
 946                         if (intarg == 0) {
 947                                 btrfs_info(info,
 948                                            "using default commit interval %us",
 949                                            BTRFS_DEFAULT_COMMIT_INTERVAL);
 950                                 intarg = BTRFS_DEFAULT_COMMIT_INTERVAL;
 951                         } else if (intarg > 300) {
 952                                 btrfs_warn(info, "excessive commit interval %d",
 953                                            intarg);
 954                         }
 955                         info->commit_interval = intarg;
 956                         break;
 957                 case Opt_rescue:
 958                         ret = parse_rescue_options(info, args[0].from);
 959                         if (ret < 0) {
 960                                 btrfs_err(info, "unrecognized rescue value %s",
 961                                           args[0].from);
 962                                 goto out;
 963                         }
 964                         break;
 965 #ifdef CONFIG_BTRFS_DEBUG
 966                 case Opt_fragment_all:
 967                         btrfs_info(info, "fragmenting all space");
 968                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 969                         btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
 970                         break;
 971                 case Opt_fragment_metadata:
 972                         btrfs_info(info, "fragmenting metadata");
 973                         btrfs_set_opt(info->mount_opt,
 974                                       FRAGMENT_METADATA);
 975                         break;
 976                 case Opt_fragment_data:
 977                         btrfs_info(info, "fragmenting data");
 978                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 979                         break;
 980 #endif
 981 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 982                 case Opt_ref_verify:
 983                         btrfs_info(info, "doing ref verification");
 984                         btrfs_set_opt(info->mount_opt, REF_VERIFY);
 985                         break;
 986 #endif
 987                 case Opt_err:
 988                         btrfs_err(info, "unrecognized mount option '%s'", p);
 989                         ret = -EINVAL;
 990                         goto out;
 991                 default:
 992                         break;
 993                 }
 994         }
 995 check:
 996         /*
 997          * Extra check for current option against current flag
 998          */
 999         if (btrfs_test_opt(info, NOLOGREPLAY) && !(new_flags & SB_RDONLY)) {
1000                 btrfs_err(info,
1001                           "nologreplay must be used with ro mount option");
1002                 ret = -EINVAL;
1003         }
1004 out:
1005         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) &&
1006             !btrfs_test_opt(info, FREE_SPACE_TREE) &&
1007             !btrfs_test_opt(info, CLEAR_CACHE)) {
1008                 btrfs_err(info, "cannot disable free space tree");
1009                 ret = -EINVAL;
1010
1011         }
1012         if (!ret && btrfs_test_opt(info, SPACE_CACHE))
1013                 btrfs_info(info, "disk space caching is enabled");
1014         if (!ret && btrfs_test_opt(info, FREE_SPACE_TREE))
1015                 btrfs_info(info, "using free space tree");
1016         return ret;
1017 }
1018
1019 /*
1020  * Parse mount options that are required early in the mount process.
1021  *
1022  * All other options will be parsed on much later in the mount process and
1023  * only when we need to allocate a new super block.
1024  */
1025 static int btrfs_parse_device_options(const char *options, fmode_t flags,
1026                                       void *holder)
1027 {
1028         substring_t args[MAX_OPT_ARGS];
1029         char *device_name, *opts, *orig, *p;
1030         struct btrfs_device *device = NULL;
1031         int error = 0;
1032
1033         lockdep_assert_held(&uuid_mutex);
1034
1035         if (!options)
1036                 return 0;
1037
1038         /*
1039          * strsep changes the string, duplicate it because btrfs_parse_options
1040          * gets called later
1041          */
1042         opts = kstrdup(options, GFP_KERNEL);
1043         if (!opts)
1044                 return -ENOMEM;
1045         orig = opts;
1046
1047         while ((p = strsep(&opts, ",")) != NULL) {
1048                 int token;
1049
1050                 if (!*p)
1051                         continue;
1052
1053                 token = match_token(p, tokens, args);
1054                 if (token == Opt_device) {
1055                         device_name = match_strdup(&args[0]);
1056                         if (!device_name) {
1057                                 error = -ENOMEM;
1058                                 goto out;
1059                         }
1060                         device = btrfs_scan_one_device(device_name, flags,
1061                                         holder);
1062                         kfree(device_name);
1063                         if (IS_ERR(device)) {
1064                                 error = PTR_ERR(device);
1065                                 goto out;
1066                         }
1067                 }
1068         }
1069
1070 out:
1071         kfree(orig);
1072         return error;
1073 }
1074
1075 /*
1076  * Parse mount options that are related to subvolume id
1077  *
1078  * The value is later passed to mount_subvol()
1079  */
1080 static int btrfs_parse_subvol_options(const char *options, char **subvol_name,
1081                 u64 *subvol_objectid)
1082 {
1083         substring_t args[MAX_OPT_ARGS];
1084         char *opts, *orig, *p;
1085         int error = 0;
1086         u64 subvolid;
1087
1088         if (!options)
1089                 return 0;
1090
1091         /*
1092          * strsep changes the string, duplicate it because
1093          * btrfs_parse_device_options gets called later
1094          */
1095         opts = kstrdup(options, GFP_KERNEL);
1096         if (!opts)
1097                 return -ENOMEM;
1098         orig = opts;
1099
1100         while ((p = strsep(&opts, ",")) != NULL) {
1101                 int token;
1102                 if (!*p)
1103                         continue;
1104
1105                 token = match_token(p, tokens, args);
1106                 switch (token) {
1107                 case Opt_subvol:
1108                         kfree(*subvol_name);
1109                         *subvol_name = match_strdup(&args[0]);
1110                         if (!*subvol_name) {
1111                                 error = -ENOMEM;
1112                                 goto out;
1113                         }
1114                         break;
1115                 case Opt_subvolid:
1116                         error = match_u64(&args[0], &subvolid);
1117                         if (error)
1118                                 goto out;
1119
1120                         /* we want the original fs_tree */
1121                         if (subvolid == 0)
1122                                 subvolid = BTRFS_FS_TREE_OBJECTID;
1123
1124                         *subvol_objectid = subvolid;
1125                         break;
1126                 default:
1127                         break;
1128                 }
1129         }
1130
1131 out:
1132         kfree(orig);
1133         return error;
1134 }
1135
1136 char *btrfs_get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
1137                                           u64 subvol_objectid)
1138 {
1139         struct btrfs_root *root = fs_info->tree_root;
1140         struct btrfs_root *fs_root = NULL;
1141         struct btrfs_root_ref *root_ref;
1142         struct btrfs_inode_ref *inode_ref;
1143         struct btrfs_key key;
1144         struct btrfs_path *path = NULL;
1145         char *name = NULL, *ptr;
1146         u64 dirid;
1147         int len;
1148         int ret;
1149
1150         path = btrfs_alloc_path();
1151         if (!path) {
1152                 ret = -ENOMEM;
1153                 goto err;
1154         }
1155         path->leave_spinning = 1;
1156
1157         name = kmalloc(PATH_MAX, GFP_KERNEL);
1158         if (!name) {
1159                 ret = -ENOMEM;
1160                 goto err;
1161         }
1162         ptr = name + PATH_MAX - 1;
1163         ptr[0] = '\0';
1164
1165         /*
1166          * Walk up the subvolume trees in the tree of tree roots by root
1167          * backrefs until we hit the top-level subvolume.
1168          */
1169         while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
1170                 key.objectid = subvol_objectid;
1171                 key.type = BTRFS_ROOT_BACKREF_KEY;
1172                 key.offset = (u64)-1;
1173
1174                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1175                 if (ret < 0) {
1176                         goto err;
1177                 } else if (ret > 0) {
1178                         ret = btrfs_previous_item(root, path, subvol_objectid,
1179                                                   BTRFS_ROOT_BACKREF_KEY);
1180                         if (ret < 0) {
1181                                 goto err;
1182                         } else if (ret > 0) {
1183                                 ret = -ENOENT;
1184                                 goto err;
1185                         }
1186                 }
1187
1188                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1189                 subvol_objectid = key.offset;
1190
1191                 root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1192                                           struct btrfs_root_ref);
1193                 len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
1194                 ptr -= len + 1;
1195                 if (ptr < name) {
1196                         ret = -ENAMETOOLONG;
1197                         goto err;
1198                 }
1199                 read_extent_buffer(path->nodes[0], ptr + 1,
1200                                    (unsigned long)(root_ref + 1), len);
1201                 ptr[0] = '/';
1202                 dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
1203                 btrfs_release_path(path);
1204
1205                 fs_root = btrfs_get_fs_root(fs_info, subvol_objectid, true);
1206                 if (IS_ERR(fs_root)) {
1207                         ret = PTR_ERR(fs_root);
1208                         fs_root = NULL;
1209                         goto err;
1210                 }
1211
1212                 /*
1213                  * Walk up the filesystem tree by inode refs until we hit the
1214                  * root directory.
1215                  */
1216                 while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
1217                         key.objectid = dirid;
1218                         key.type = BTRFS_INODE_REF_KEY;
1219                         key.offset = (u64)-1;
1220
1221                         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1222                         if (ret < 0) {
1223                                 goto err;
1224                         } else if (ret > 0) {
1225                                 ret = btrfs_previous_item(fs_root, path, dirid,
1226                                                           BTRFS_INODE_REF_KEY);
1227                                 if (ret < 0) {
1228                                         goto err;
1229                                 } else if (ret > 0) {
1230                                         ret = -ENOENT;
1231                                         goto err;
1232                                 }
1233                         }
1234
1235                         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1236                         dirid = key.offset;
1237
1238                         inode_ref = btrfs_item_ptr(path->nodes[0],
1239                                                    path->slots[0],
1240                                                    struct btrfs_inode_ref);
1241                         len = btrfs_inode_ref_name_len(path->nodes[0],
1242                                                        inode_ref);
1243                         ptr -= len + 1;
1244                         if (ptr < name) {
1245                                 ret = -ENAMETOOLONG;
1246                                 goto err;
1247                         }
1248                         read_extent_buffer(path->nodes[0], ptr + 1,
1249                                            (unsigned long)(inode_ref + 1), len);
1250                         ptr[0] = '/';
1251                         btrfs_release_path(path);
1252                 }
1253                 btrfs_put_root(fs_root);
1254                 fs_root = NULL;
1255         }
1256
1257         btrfs_free_path(path);
1258         if (ptr == name + PATH_MAX - 1) {
1259                 name[0] = '/';
1260                 name[1] = '\0';
1261         } else {
1262                 memmove(name, ptr, name + PATH_MAX - ptr);
1263         }
1264         return name;
1265
1266 err:
1267         btrfs_put_root(fs_root);
1268         btrfs_free_path(path);
1269         kfree(name);
1270         return ERR_PTR(ret);
1271 }
1272
1273 static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
1274 {
1275         struct btrfs_root *root = fs_info->tree_root;
1276         struct btrfs_dir_item *di;
1277         struct btrfs_path *path;
1278         struct btrfs_key location;
1279         u64 dir_id;
1280
1281         path = btrfs_alloc_path();
1282         if (!path)
1283                 return -ENOMEM;
1284         path->leave_spinning = 1;
1285
1286         /*
1287          * Find the "default" dir item which points to the root item that we
1288          * will mount by default if we haven't been given a specific subvolume
1289          * to mount.
1290          */
1291         dir_id = btrfs_super_root_dir(fs_info->super_copy);
1292         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
1293         if (IS_ERR(di)) {
1294                 btrfs_free_path(path);
1295                 return PTR_ERR(di);
1296         }
1297         if (!di) {
1298                 /*
1299                  * Ok the default dir item isn't there.  This is weird since
1300                  * it's always been there, but don't freak out, just try and
1301                  * mount the top-level subvolume.
1302                  */
1303                 btrfs_free_path(path);
1304                 *objectid = BTRFS_FS_TREE_OBJECTID;
1305                 return 0;
1306         }
1307
1308         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
1309         btrfs_free_path(path);
1310         *objectid = location.objectid;
1311         return 0;
1312 }
1313
1314 static int btrfs_fill_super(struct super_block *sb,
1315                             struct btrfs_fs_devices *fs_devices,
1316                             void *data)
1317 {
1318         struct inode *inode;
1319         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1320         int err;
1321
1322         sb->s_maxbytes = MAX_LFS_FILESIZE;
1323         sb->s_magic = BTRFS_SUPER_MAGIC;
1324         sb->s_op = &btrfs_super_ops;
1325         sb->s_d_op = &btrfs_dentry_operations;
1326         sb->s_export_op = &btrfs_export_ops;
1327         sb->s_xattr = btrfs_xattr_handlers;
1328         sb->s_time_gran = 1;
1329 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
1330         sb->s_flags |= SB_POSIXACL;
1331 #endif
1332         sb->s_flags |= SB_I_VERSION;
1333         sb->s_iflags |= SB_I_CGROUPWB;
1334
1335         err = super_setup_bdi(sb);
1336         if (err) {
1337                 btrfs_err(fs_info, "super_setup_bdi failed");
1338                 return err;
1339         }
1340
1341         err = open_ctree(sb, fs_devices, (char *)data);
1342         if (err) {
1343                 btrfs_err(fs_info, "open_ctree failed");
1344                 return err;
1345         }
1346
1347         inode = btrfs_iget(sb, BTRFS_FIRST_FREE_OBJECTID, fs_info->fs_root);
1348         if (IS_ERR(inode)) {
1349                 err = PTR_ERR(inode);
1350                 goto fail_close;
1351         }
1352
1353         sb->s_root = d_make_root(inode);
1354         if (!sb->s_root) {
1355                 err = -ENOMEM;
1356                 goto fail_close;
1357         }
1358
1359         cleancache_init_fs(sb);
1360         sb->s_flags |= SB_ACTIVE;
1361         return 0;
1362
1363 fail_close:
1364         close_ctree(fs_info);
1365         return err;
1366 }
1367
1368 int btrfs_sync_fs(struct super_block *sb, int wait)
1369 {
1370         struct btrfs_trans_handle *trans;
1371         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1372         struct btrfs_root *root = fs_info->tree_root;
1373
1374         trace_btrfs_sync_fs(fs_info, wait);
1375
1376         if (!wait) {
1377                 filemap_flush(fs_info->btree_inode->i_mapping);
1378                 return 0;
1379         }
1380
1381         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
1382
1383         trans = btrfs_attach_transaction_barrier(root);
1384         if (IS_ERR(trans)) {
1385                 /* no transaction, don't bother */
1386                 if (PTR_ERR(trans) == -ENOENT) {
1387                         /*
1388                          * Exit unless we have some pending changes
1389                          * that need to go through commit
1390                          */
1391                         if (fs_info->pending_changes == 0)
1392                                 return 0;
1393                         /*
1394                          * A non-blocking test if the fs is frozen. We must not
1395                          * start a new transaction here otherwise a deadlock
1396                          * happens. The pending operations are delayed to the
1397                          * next commit after thawing.
1398                          */
1399                         if (sb_start_write_trylock(sb))
1400                                 sb_end_write(sb);
1401                         else
1402                                 return 0;
1403                         trans = btrfs_start_transaction(root, 0);
1404                 }
1405                 if (IS_ERR(trans))
1406                         return PTR_ERR(trans);
1407         }
1408         return btrfs_commit_transaction(trans);
1409 }
1410
1411 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1412 {
1413         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1414         const char *compress_type;
1415         const char *subvol_name;
1416
1417         if (btrfs_test_opt(info, DEGRADED))
1418                 seq_puts(seq, ",degraded");
1419         if (btrfs_test_opt(info, NODATASUM))
1420                 seq_puts(seq, ",nodatasum");
1421         if (btrfs_test_opt(info, NODATACOW))
1422                 seq_puts(seq, ",nodatacow");
1423         if (btrfs_test_opt(info, NOBARRIER))
1424                 seq_puts(seq, ",nobarrier");
1425         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1426                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
1427         if (info->thread_pool_size !=  min_t(unsigned long,
1428                                              num_online_cpus() + 2, 8))
1429                 seq_printf(seq, ",thread_pool=%u", info->thread_pool_size);
1430         if (btrfs_test_opt(info, COMPRESS)) {
1431                 compress_type = btrfs_compress_type2str(info->compress_type);
1432                 if (btrfs_test_opt(info, FORCE_COMPRESS))
1433                         seq_printf(seq, ",compress-force=%s", compress_type);
1434                 else
1435                         seq_printf(seq, ",compress=%s", compress_type);
1436                 if (info->compress_level)
1437                         seq_printf(seq, ":%d", info->compress_level);
1438         }
1439         if (btrfs_test_opt(info, NOSSD))
1440                 seq_puts(seq, ",nossd");
1441         if (btrfs_test_opt(info, SSD_SPREAD))
1442                 seq_puts(seq, ",ssd_spread");
1443         else if (btrfs_test_opt(info, SSD))
1444                 seq_puts(seq, ",ssd");
1445         if (btrfs_test_opt(info, NOTREELOG))
1446                 seq_puts(seq, ",notreelog");
1447         if (btrfs_test_opt(info, NOLOGREPLAY))
1448                 seq_puts(seq, ",rescue=nologreplay");
1449         if (btrfs_test_opt(info, FLUSHONCOMMIT))
1450                 seq_puts(seq, ",flushoncommit");
1451         if (btrfs_test_opt(info, DISCARD_SYNC))
1452                 seq_puts(seq, ",discard");
1453         if (btrfs_test_opt(info, DISCARD_ASYNC))
1454                 seq_puts(seq, ",discard=async");
1455         if (!(info->sb->s_flags & SB_POSIXACL))
1456                 seq_puts(seq, ",noacl");
1457         if (btrfs_test_opt(info, SPACE_CACHE))
1458                 seq_puts(seq, ",space_cache");
1459         else if (btrfs_test_opt(info, FREE_SPACE_TREE))
1460                 seq_puts(seq, ",space_cache=v2");
1461         else
1462                 seq_puts(seq, ",nospace_cache");
1463         if (btrfs_test_opt(info, RESCAN_UUID_TREE))
1464                 seq_puts(seq, ",rescan_uuid_tree");
1465         if (btrfs_test_opt(info, CLEAR_CACHE))
1466                 seq_puts(seq, ",clear_cache");
1467         if (btrfs_test_opt(info, USER_SUBVOL_RM_ALLOWED))
1468                 seq_puts(seq, ",user_subvol_rm_allowed");
1469         if (btrfs_test_opt(info, ENOSPC_DEBUG))
1470                 seq_puts(seq, ",enospc_debug");
1471         if (btrfs_test_opt(info, AUTO_DEFRAG))
1472                 seq_puts(seq, ",autodefrag");
1473         if (btrfs_test_opt(info, INODE_MAP_CACHE))
1474                 seq_puts(seq, ",inode_cache");
1475         if (btrfs_test_opt(info, SKIP_BALANCE))
1476                 seq_puts(seq, ",skip_balance");
1477 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1478         if (btrfs_test_opt(info, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
1479                 seq_puts(seq, ",check_int_data");
1480         else if (btrfs_test_opt(info, CHECK_INTEGRITY))
1481                 seq_puts(seq, ",check_int");
1482         if (info->check_integrity_print_mask)
1483                 seq_printf(seq, ",check_int_print_mask=%d",
1484                                 info->check_integrity_print_mask);
1485 #endif
1486         if (info->metadata_ratio)
1487                 seq_printf(seq, ",metadata_ratio=%u", info->metadata_ratio);
1488         if (btrfs_test_opt(info, PANIC_ON_FATAL_ERROR))
1489                 seq_puts(seq, ",fatal_errors=panic");
1490         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1491                 seq_printf(seq, ",commit=%u", info->commit_interval);
1492 #ifdef CONFIG_BTRFS_DEBUG
1493         if (btrfs_test_opt(info, FRAGMENT_DATA))
1494                 seq_puts(seq, ",fragment=data");
1495         if (btrfs_test_opt(info, FRAGMENT_METADATA))
1496                 seq_puts(seq, ",fragment=metadata");
1497 #endif
1498         if (btrfs_test_opt(info, REF_VERIFY))
1499                 seq_puts(seq, ",ref_verify");
1500         seq_printf(seq, ",subvolid=%llu",
1501                   BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1502         subvol_name = btrfs_get_subvol_name_from_objectid(info,
1503                         BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1504         if (!IS_ERR(subvol_name)) {
1505                 seq_puts(seq, ",subvol=");
1506                 seq_escape(seq, subvol_name, " \t\n\\");
1507                 kfree(subvol_name);
1508         }
1509         return 0;
1510 }
1511
1512 static int btrfs_test_super(struct super_block *s, void *data)
1513 {
1514         struct btrfs_fs_info *p = data;
1515         struct btrfs_fs_info *fs_info = btrfs_sb(s);
1516
1517         return fs_info->fs_devices == p->fs_devices;
1518 }
1519
1520 static int btrfs_set_super(struct super_block *s, void *data)
1521 {
1522         int err = set_anon_super(s, data);
1523         if (!err)
1524                 s->s_fs_info = data;
1525         return err;
1526 }
1527
1528 /*
1529  * subvolumes are identified by ino 256
1530  */
1531 static inline int is_subvolume_inode(struct inode *inode)
1532 {
1533         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1534                 return 1;
1535         return 0;
1536 }
1537
1538 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
1539                                    struct vfsmount *mnt)
1540 {
1541         struct dentry *root;
1542         int ret;
1543
1544         if (!subvol_name) {
1545                 if (!subvol_objectid) {
1546                         ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
1547                                                           &subvol_objectid);
1548                         if (ret) {
1549                                 root = ERR_PTR(ret);
1550                                 goto out;
1551                         }
1552                 }
1553                 subvol_name = btrfs_get_subvol_name_from_objectid(
1554                                         btrfs_sb(mnt->mnt_sb), subvol_objectid);
1555                 if (IS_ERR(subvol_name)) {
1556                         root = ERR_CAST(subvol_name);
1557                         subvol_name = NULL;
1558                         goto out;
1559                 }
1560
1561         }
1562
1563         root = mount_subtree(mnt, subvol_name);
1564         /* mount_subtree() drops our reference on the vfsmount. */
1565         mnt = NULL;
1566
1567         if (!IS_ERR(root)) {
1568                 struct super_block *s = root->d_sb;
1569                 struct btrfs_fs_info *fs_info = btrfs_sb(s);
1570                 struct inode *root_inode = d_inode(root);
1571                 u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
1572
1573                 ret = 0;
1574                 if (!is_subvolume_inode(root_inode)) {
1575                         btrfs_err(fs_info, "'%s' is not a valid subvolume",
1576                                subvol_name);
1577                         ret = -EINVAL;
1578                 }
1579                 if (subvol_objectid && root_objectid != subvol_objectid) {
1580                         /*
1581                          * This will also catch a race condition where a
1582                          * subvolume which was passed by ID is renamed and
1583                          * another subvolume is renamed over the old location.
1584                          */
1585                         btrfs_err(fs_info,
1586                                   "subvol '%s' does not match subvolid %llu",
1587                                   subvol_name, subvol_objectid);
1588                         ret = -EINVAL;
1589                 }
1590                 if (ret) {
1591                         dput(root);
1592                         root = ERR_PTR(ret);
1593                         deactivate_locked_super(s);
1594                 }
1595         }
1596
1597 out:
1598         mntput(mnt);
1599         kfree(subvol_name);
1600         return root;
1601 }
1602
1603 /*
1604  * Find a superblock for the given device / mount point.
1605  *
1606  * Note: This is based on mount_bdev from fs/super.c with a few additions
1607  *       for multiple device setup.  Make sure to keep it in sync.
1608  */
1609 static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
1610                 int flags, const char *device_name, void *data)
1611 {
1612         struct block_device *bdev = NULL;
1613         struct super_block *s;
1614         struct btrfs_device *device = NULL;
1615         struct btrfs_fs_devices *fs_devices = NULL;
1616         struct btrfs_fs_info *fs_info = NULL;
1617         void *new_sec_opts = NULL;
1618         fmode_t mode = FMODE_READ;
1619         int error = 0;
1620
1621         if (!(flags & SB_RDONLY))
1622                 mode |= FMODE_WRITE;
1623
1624         if (data) {
1625                 error = security_sb_eat_lsm_opts(data, &new_sec_opts);
1626                 if (error)
1627                         return ERR_PTR(error);
1628         }
1629
1630         /*
1631          * Setup a dummy root and fs_info for test/set super.  This is because
1632          * we don't actually fill this stuff out until open_ctree, but we need
1633          * then open_ctree will properly initialize the file system specific
1634          * settings later.  btrfs_init_fs_info initializes the static elements
1635          * of the fs_info (locks and such) to make cleanup easier if we find a
1636          * superblock with our given fs_devices later on at sget() time.
1637          */
1638         fs_info = kvzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
1639         if (!fs_info) {
1640                 error = -ENOMEM;
1641                 goto error_sec_opts;
1642         }
1643         btrfs_init_fs_info(fs_info);
1644
1645         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1646         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1647         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1648                 error = -ENOMEM;
1649                 goto error_fs_info;
1650         }
1651
1652         mutex_lock(&uuid_mutex);
1653         error = btrfs_parse_device_options(data, mode, fs_type);
1654         if (error) {
1655                 mutex_unlock(&uuid_mutex);
1656                 goto error_fs_info;
1657         }
1658
1659         device = btrfs_scan_one_device(device_name, mode, fs_type);
1660         if (IS_ERR(device)) {
1661                 mutex_unlock(&uuid_mutex);
1662                 error = PTR_ERR(device);
1663                 goto error_fs_info;
1664         }
1665
1666         fs_devices = device->fs_devices;
1667         fs_info->fs_devices = fs_devices;
1668
1669         error = btrfs_open_devices(fs_devices, mode, fs_type);
1670         mutex_unlock(&uuid_mutex);
1671         if (error)
1672                 goto error_fs_info;
1673
1674         if (!(flags & SB_RDONLY) && fs_devices->rw_devices == 0) {
1675                 error = -EACCES;
1676                 goto error_close_devices;
1677         }
1678
1679         bdev = fs_devices->latest_bdev;
1680         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | SB_NOSEC,
1681                  fs_info);
1682         if (IS_ERR(s)) {
1683                 error = PTR_ERR(s);
1684                 goto error_close_devices;
1685         }
1686
1687         if (s->s_root) {
1688                 btrfs_close_devices(fs_devices);
1689                 btrfs_free_fs_info(fs_info);
1690                 if ((flags ^ s->s_flags) & SB_RDONLY)
1691                         error = -EBUSY;
1692         } else {
1693                 snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
1694                 btrfs_sb(s)->bdev_holder = fs_type;
1695                 error = btrfs_fill_super(s, fs_devices, data);
1696         }
1697         if (!error)
1698                 error = security_sb_set_mnt_opts(s, new_sec_opts, 0, NULL);
1699         security_free_mnt_opts(&new_sec_opts);
1700         if (error) {
1701                 deactivate_locked_super(s);
1702                 return ERR_PTR(error);
1703         }
1704
1705         return dget(s->s_root);
1706
1707 error_close_devices:
1708         btrfs_close_devices(fs_devices);
1709 error_fs_info:
1710         btrfs_free_fs_info(fs_info);
1711 error_sec_opts:
1712         security_free_mnt_opts(&new_sec_opts);
1713         return ERR_PTR(error);
1714 }
1715
1716 /*
1717  * Mount function which is called by VFS layer.
1718  *
1719  * In order to allow mounting a subvolume directly, btrfs uses mount_subtree()
1720  * which needs vfsmount* of device's root (/).  This means device's root has to
1721  * be mounted internally in any case.
1722  *
1723  * Operation flow:
1724  *   1. Parse subvol id related options for later use in mount_subvol().
1725  *
1726  *   2. Mount device's root (/) by calling vfs_kern_mount().
1727  *
1728  *      NOTE: vfs_kern_mount() is used by VFS to call btrfs_mount() in the
1729  *      first place. In order to avoid calling btrfs_mount() again, we use
1730  *      different file_system_type which is not registered to VFS by
1731  *      register_filesystem() (btrfs_root_fs_type). As a result,
1732  *      btrfs_mount_root() is called. The return value will be used by
1733  *      mount_subtree() in mount_subvol().
1734  *
1735  *   3. Call mount_subvol() to get the dentry of subvolume. Since there is
1736  *      "btrfs subvolume set-default", mount_subvol() is called always.
1737  */
1738 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1739                 const char *device_name, void *data)
1740 {
1741         struct vfsmount *mnt_root;
1742         struct dentry *root;
1743         char *subvol_name = NULL;
1744         u64 subvol_objectid = 0;
1745         int error = 0;
1746
1747         error = btrfs_parse_subvol_options(data, &subvol_name,
1748                                         &subvol_objectid);
1749         if (error) {
1750                 kfree(subvol_name);
1751                 return ERR_PTR(error);
1752         }
1753
1754         /* mount device's root (/) */
1755         mnt_root = vfs_kern_mount(&btrfs_root_fs_type, flags, device_name, data);
1756         if (PTR_ERR_OR_ZERO(mnt_root) == -EBUSY) {
1757                 if (flags & SB_RDONLY) {
1758                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1759                                 flags & ~SB_RDONLY, device_name, data);
1760                 } else {
1761                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1762                                 flags | SB_RDONLY, device_name, data);
1763                         if (IS_ERR(mnt_root)) {
1764                                 root = ERR_CAST(mnt_root);
1765                                 kfree(subvol_name);
1766                                 goto out;
1767                         }
1768
1769                         down_write(&mnt_root->mnt_sb->s_umount);
1770                         error = btrfs_remount(mnt_root->mnt_sb, &flags, NULL);
1771                         up_write(&mnt_root->mnt_sb->s_umount);
1772                         if (error < 0) {
1773                                 root = ERR_PTR(error);
1774                                 mntput(mnt_root);
1775                                 kfree(subvol_name);
1776                                 goto out;
1777                         }
1778                 }
1779         }
1780         if (IS_ERR(mnt_root)) {
1781                 root = ERR_CAST(mnt_root);
1782                 kfree(subvol_name);
1783                 goto out;
1784         }
1785
1786         /* mount_subvol() will free subvol_name and mnt_root */
1787         root = mount_subvol(subvol_name, subvol_objectid, mnt_root);
1788
1789 out:
1790         return root;
1791 }
1792
1793 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1794                                      u32 new_pool_size, u32 old_pool_size)
1795 {
1796         if (new_pool_size == old_pool_size)
1797                 return;
1798
1799         fs_info->thread_pool_size = new_pool_size;
1800
1801         btrfs_info(fs_info, "resize thread pool %d -> %d",
1802                old_pool_size, new_pool_size);
1803
1804         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1805         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1806         btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1807         btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
1808         btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
1809         btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
1810                                 new_pool_size);
1811         btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1812         btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1813         btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1814         btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
1815         btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
1816                                 new_pool_size);
1817 }
1818
1819 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1820                                        unsigned long old_opts, int flags)
1821 {
1822         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1823             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1824              (flags & SB_RDONLY))) {
1825                 /* wait for any defraggers to finish */
1826                 wait_event(fs_info->transaction_wait,
1827                            (atomic_read(&fs_info->defrag_running) == 0));
1828                 if (flags & SB_RDONLY)
1829                         sync_filesystem(fs_info->sb);
1830         }
1831 }
1832
1833 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1834                                          unsigned long old_opts)
1835 {
1836         /*
1837          * We need to cleanup all defragable inodes if the autodefragment is
1838          * close or the filesystem is read only.
1839          */
1840         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1841             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) || sb_rdonly(fs_info->sb))) {
1842                 btrfs_cleanup_defrag_inodes(fs_info);
1843         }
1844
1845         /* If we toggled discard async */
1846         if (!btrfs_raw_test_opt(old_opts, DISCARD_ASYNC) &&
1847             btrfs_test_opt(fs_info, DISCARD_ASYNC))
1848                 btrfs_discard_resume(fs_info);
1849         else if (btrfs_raw_test_opt(old_opts, DISCARD_ASYNC) &&
1850                  !btrfs_test_opt(fs_info, DISCARD_ASYNC))
1851                 btrfs_discard_cleanup(fs_info);
1852 }
1853
1854 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1855 {
1856         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1857         struct btrfs_root *root = fs_info->tree_root;
1858         unsigned old_flags = sb->s_flags;
1859         unsigned long old_opts = fs_info->mount_opt;
1860         unsigned long old_compress_type = fs_info->compress_type;
1861         u64 old_max_inline = fs_info->max_inline;
1862         u32 old_thread_pool_size = fs_info->thread_pool_size;
1863         u32 old_metadata_ratio = fs_info->metadata_ratio;
1864         int ret;
1865
1866         sync_filesystem(sb);
1867         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1868
1869         if (data) {
1870                 void *new_sec_opts = NULL;
1871
1872                 ret = security_sb_eat_lsm_opts(data, &new_sec_opts);
1873                 if (!ret)
1874                         ret = security_sb_remount(sb, new_sec_opts);
1875                 security_free_mnt_opts(&new_sec_opts);
1876                 if (ret)
1877                         goto restore;
1878         }
1879
1880         ret = btrfs_parse_options(fs_info, data, *flags);
1881         if (ret)
1882                 goto restore;
1883
1884         btrfs_remount_begin(fs_info, old_opts, *flags);
1885         btrfs_resize_thread_pool(fs_info,
1886                 fs_info->thread_pool_size, old_thread_pool_size);
1887
1888         if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
1889                 goto out;
1890
1891         if (*flags & SB_RDONLY) {
1892                 /*
1893                  * this also happens on 'umount -rf' or on shutdown, when
1894                  * the filesystem is busy.
1895                  */
1896                 cancel_work_sync(&fs_info->async_reclaim_work);
1897                 cancel_work_sync(&fs_info->async_data_reclaim_work);
1898
1899                 btrfs_discard_cleanup(fs_info);
1900
1901                 /* wait for the uuid_scan task to finish */
1902                 down(&fs_info->uuid_tree_rescan_sem);
1903                 /* avoid complains from lockdep et al. */
1904                 up(&fs_info->uuid_tree_rescan_sem);
1905
1906                 sb->s_flags |= SB_RDONLY;
1907
1908                 /*
1909                  * Setting SB_RDONLY will put the cleaner thread to
1910                  * sleep at the next loop if it's already active.
1911                  * If it's already asleep, we'll leave unused block
1912                  * groups on disk until we're mounted read-write again
1913                  * unless we clean them up here.
1914                  */
1915                 btrfs_delete_unused_bgs(fs_info);
1916
1917                 btrfs_dev_replace_suspend_for_unmount(fs_info);
1918                 btrfs_scrub_cancel(fs_info);
1919                 btrfs_pause_balance(fs_info);
1920
1921                 /*
1922                  * Pause the qgroup rescan worker if it is running. We don't want
1923                  * it to be still running after we are in RO mode, as after that,
1924                  * by the time we unmount, it might have left a transaction open,
1925                  * so we would leak the transaction and/or crash.
1926                  */
1927                 btrfs_qgroup_wait_for_completion(fs_info, false);
1928
1929                 ret = btrfs_commit_super(fs_info);
1930                 if (ret)
1931                         goto restore;
1932         } else {
1933                 if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
1934                         btrfs_err(fs_info,
1935                                 "Remounting read-write after error is not allowed");
1936                         ret = -EINVAL;
1937                         goto restore;
1938                 }
1939                 if (fs_info->fs_devices->rw_devices == 0) {
1940                         ret = -EACCES;
1941                         goto restore;
1942                 }
1943
1944                 if (!btrfs_check_rw_degradable(fs_info, NULL)) {
1945                         btrfs_warn(fs_info,
1946                 "too many missing devices, writable remount is not allowed");
1947                         ret = -EACCES;
1948                         goto restore;
1949                 }
1950
1951                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1952                         btrfs_warn(fs_info,
1953                 "mount required to replay tree-log, cannot remount read-write");
1954                         ret = -EINVAL;
1955                         goto restore;
1956                 }
1957
1958                 ret = btrfs_cleanup_fs_roots(fs_info);
1959                 if (ret)
1960                         goto restore;
1961
1962                 /* recover relocation */
1963                 mutex_lock(&fs_info->cleaner_mutex);
1964                 ret = btrfs_recover_relocation(root);
1965                 mutex_unlock(&fs_info->cleaner_mutex);
1966                 if (ret)
1967                         goto restore;
1968
1969                 ret = btrfs_resume_balance_async(fs_info);
1970                 if (ret)
1971                         goto restore;
1972
1973                 ret = btrfs_resume_dev_replace_async(fs_info);
1974                 if (ret) {
1975                         btrfs_warn(fs_info, "failed to resume dev_replace");
1976                         goto restore;
1977                 }
1978
1979                 btrfs_qgroup_rescan_resume(fs_info);
1980
1981                 if (!fs_info->uuid_root) {
1982                         btrfs_info(fs_info, "creating UUID tree");
1983                         ret = btrfs_create_uuid_tree(fs_info);
1984                         if (ret) {
1985                                 btrfs_warn(fs_info,
1986                                            "failed to create the UUID tree %d",
1987                                            ret);
1988                                 goto restore;
1989                         }
1990                 }
1991                 sb->s_flags &= ~SB_RDONLY;
1992
1993                 set_bit(BTRFS_FS_OPEN, &fs_info->flags);
1994         }
1995 out:
1996         /*
1997          * We need to set SB_I_VERSION here otherwise it'll get cleared by VFS,
1998          * since the absence of the flag means it can be toggled off by remount.
1999          */
2000         *flags |= SB_I_VERSION;
2001
2002         wake_up_process(fs_info->transaction_kthread);
2003         btrfs_remount_cleanup(fs_info, old_opts);
2004         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
2005
2006         return 0;
2007
2008 restore:
2009         /* We've hit an error - don't reset SB_RDONLY */
2010         if (sb_rdonly(sb))
2011                 old_flags |= SB_RDONLY;
2012         sb->s_flags = old_flags;
2013         fs_info->mount_opt = old_opts;
2014         fs_info->compress_type = old_compress_type;
2015         fs_info->max_inline = old_max_inline;
2016         btrfs_resize_thread_pool(fs_info,
2017                 old_thread_pool_size, fs_info->thread_pool_size);
2018         fs_info->metadata_ratio = old_metadata_ratio;
2019         btrfs_remount_cleanup(fs_info, old_opts);
2020         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
2021
2022         return ret;
2023 }
2024
2025 /* Used to sort the devices by max_avail(descending sort) */
2026 static inline int btrfs_cmp_device_free_bytes(const void *dev_info1,
2027                                        const void *dev_info2)
2028 {
2029         if (((struct btrfs_device_info *)dev_info1)->max_avail >
2030             ((struct btrfs_device_info *)dev_info2)->max_avail)
2031                 return -1;
2032         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
2033                  ((struct btrfs_device_info *)dev_info2)->max_avail)
2034                 return 1;
2035         else
2036         return 0;
2037 }
2038
2039 /*
2040  * sort the devices by max_avail, in which max free extent size of each device
2041  * is stored.(Descending Sort)
2042  */
2043 static inline void btrfs_descending_sort_devices(
2044                                         struct btrfs_device_info *devices,
2045                                         size_t nr_devices)
2046 {
2047         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
2048              btrfs_cmp_device_free_bytes, NULL);
2049 }
2050
2051 /*
2052  * The helper to calc the free space on the devices that can be used to store
2053  * file data.
2054  */
2055 static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
2056                                               u64 *free_bytes)
2057 {
2058         struct btrfs_device_info *devices_info;
2059         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
2060         struct btrfs_device *device;
2061         u64 type;
2062         u64 avail_space;
2063         u64 min_stripe_size;
2064         int num_stripes = 1;
2065         int i = 0, nr_devices;
2066         const struct btrfs_raid_attr *rattr;
2067
2068         /*
2069          * We aren't under the device list lock, so this is racy-ish, but good
2070          * enough for our purposes.
2071          */
2072         nr_devices = fs_info->fs_devices->open_devices;
2073         if (!nr_devices) {
2074                 smp_mb();
2075                 nr_devices = fs_info->fs_devices->open_devices;
2076                 ASSERT(nr_devices);
2077                 if (!nr_devices) {
2078                         *free_bytes = 0;
2079                         return 0;
2080                 }
2081         }
2082
2083         devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
2084                                GFP_KERNEL);
2085         if (!devices_info)
2086                 return -ENOMEM;
2087
2088         /* calc min stripe number for data space allocation */
2089         type = btrfs_data_alloc_profile(fs_info);
2090         rattr = &btrfs_raid_array[btrfs_bg_flags_to_raid_index(type)];
2091
2092         if (type & BTRFS_BLOCK_GROUP_RAID0)
2093                 num_stripes = nr_devices;
2094         else if (type & BTRFS_BLOCK_GROUP_RAID1)
2095                 num_stripes = 2;
2096         else if (type & BTRFS_BLOCK_GROUP_RAID1C3)
2097                 num_stripes = 3;
2098         else if (type & BTRFS_BLOCK_GROUP_RAID1C4)
2099                 num_stripes = 4;
2100         else if (type & BTRFS_BLOCK_GROUP_RAID10)
2101                 num_stripes = 4;
2102
2103         /* Adjust for more than 1 stripe per device */
2104         min_stripe_size = rattr->dev_stripes * BTRFS_STRIPE_LEN;
2105
2106         rcu_read_lock();
2107         list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
2108                 if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
2109                                                 &device->dev_state) ||
2110                     !device->bdev ||
2111                     test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
2112                         continue;
2113
2114                 if (i >= nr_devices)
2115                         break;
2116
2117                 avail_space = device->total_bytes - device->bytes_used;
2118
2119                 /* align with stripe_len */
2120                 avail_space = rounddown(avail_space, BTRFS_STRIPE_LEN);
2121
2122                 /*
2123                  * In order to avoid overwriting the superblock on the drive,
2124                  * btrfs starts at an offset of at least 1MB when doing chunk
2125                  * allocation.
2126                  *
2127                  * This ensures we have at least min_stripe_size free space
2128                  * after excluding 1MB.
2129                  */
2130                 if (avail_space <= SZ_1M + min_stripe_size)
2131                         continue;
2132
2133                 avail_space -= SZ_1M;
2134
2135                 devices_info[i].dev = device;
2136                 devices_info[i].max_avail = avail_space;
2137
2138                 i++;
2139         }
2140         rcu_read_unlock();
2141
2142         nr_devices = i;
2143
2144         btrfs_descending_sort_devices(devices_info, nr_devices);
2145
2146         i = nr_devices - 1;
2147         avail_space = 0;
2148         while (nr_devices >= rattr->devs_min) {
2149                 num_stripes = min(num_stripes, nr_devices);
2150
2151                 if (devices_info[i].max_avail >= min_stripe_size) {
2152                         int j;
2153                         u64 alloc_size;
2154
2155                         avail_space += devices_info[i].max_avail * num_stripes;
2156                         alloc_size = devices_info[i].max_avail;
2157                         for (j = i + 1 - num_stripes; j <= i; j++)
2158                                 devices_info[j].max_avail -= alloc_size;
2159                 }
2160                 i--;
2161                 nr_devices--;
2162         }
2163
2164         kfree(devices_info);
2165         *free_bytes = avail_space;
2166         return 0;
2167 }
2168
2169 /*
2170  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
2171  *
2172  * If there's a redundant raid level at DATA block groups, use the respective
2173  * multiplier to scale the sizes.
2174  *
2175  * Unused device space usage is based on simulating the chunk allocator
2176  * algorithm that respects the device sizes and order of allocations.  This is
2177  * a close approximation of the actual use but there are other factors that may
2178  * change the result (like a new metadata chunk).
2179  *
2180  * If metadata is exhausted, f_bavail will be 0.
2181  */
2182 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
2183 {
2184         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
2185         struct btrfs_super_block *disk_super = fs_info->super_copy;
2186         struct btrfs_space_info *found;
2187         u64 total_used = 0;
2188         u64 total_free_data = 0;
2189         u64 total_free_meta = 0;
2190         int bits = dentry->d_sb->s_blocksize_bits;
2191         __be32 *fsid = (__be32 *)fs_info->fs_devices->fsid;
2192         unsigned factor = 1;
2193         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
2194         int ret;
2195         u64 thresh = 0;
2196         int mixed = 0;
2197
2198         list_for_each_entry(found, &fs_info->space_info, list) {
2199                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
2200                         int i;
2201
2202                         total_free_data += found->disk_total - found->disk_used;
2203                         total_free_data -=
2204                                 btrfs_account_ro_block_groups_free_space(found);
2205
2206                         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
2207                                 if (!list_empty(&found->block_groups[i]))
2208                                         factor = btrfs_bg_type_to_factor(
2209                                                 btrfs_raid_array[i].bg_flag);
2210                         }
2211                 }
2212
2213                 /*
2214                  * Metadata in mixed block goup profiles are accounted in data
2215                  */
2216                 if (!mixed && found->flags & BTRFS_BLOCK_GROUP_METADATA) {
2217                         if (found->flags & BTRFS_BLOCK_GROUP_DATA)
2218                                 mixed = 1;
2219                         else
2220                                 total_free_meta += found->disk_total -
2221                                         found->disk_used;
2222                 }
2223
2224                 total_used += found->disk_used;
2225         }
2226
2227         buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
2228         buf->f_blocks >>= bits;
2229         buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
2230
2231         /* Account global block reserve as used, it's in logical size already */
2232         spin_lock(&block_rsv->lock);
2233         /* Mixed block groups accounting is not byte-accurate, avoid overflow */
2234         if (buf->f_bfree >= block_rsv->size >> bits)
2235                 buf->f_bfree -= block_rsv->size >> bits;
2236         else
2237                 buf->f_bfree = 0;
2238         spin_unlock(&block_rsv->lock);
2239
2240         buf->f_bavail = div_u64(total_free_data, factor);
2241         ret = btrfs_calc_avail_data_space(fs_info, &total_free_data);
2242         if (ret)
2243                 return ret;
2244         buf->f_bavail += div_u64(total_free_data, factor);
2245         buf->f_bavail = buf->f_bavail >> bits;
2246
2247         /*
2248          * We calculate the remaining metadata space minus global reserve. If
2249          * this is (supposedly) smaller than zero, there's no space. But this
2250          * does not hold in practice, the exhausted state happens where's still
2251          * some positive delta. So we apply some guesswork and compare the
2252          * delta to a 4M threshold.  (Practically observed delta was ~2M.)
2253          *
2254          * We probably cannot calculate the exact threshold value because this
2255          * depends on the internal reservations requested by various
2256          * operations, so some operations that consume a few metadata will
2257          * succeed even if the Avail is zero. But this is better than the other
2258          * way around.
2259          */
2260         thresh = SZ_4M;
2261
2262         /*
2263          * We only want to claim there's no available space if we can no longer
2264          * allocate chunks for our metadata profile and our global reserve will
2265          * not fit in the free metadata space.  If we aren't ->full then we
2266          * still can allocate chunks and thus are fine using the currently
2267          * calculated f_bavail.
2268          */
2269         if (!mixed && block_rsv->space_info->full &&
2270             (total_free_meta < thresh || total_free_meta - thresh < block_rsv->size))
2271                 buf->f_bavail = 0;
2272
2273         buf->f_type = BTRFS_SUPER_MAGIC;
2274         buf->f_bsize = dentry->d_sb->s_blocksize;
2275         buf->f_namelen = BTRFS_NAME_LEN;
2276
2277         /* We treat it as constant endianness (it doesn't matter _which_)
2278            because we want the fsid to come out the same whether mounted
2279            on a big-endian or little-endian host */
2280         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
2281         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
2282         /* Mask in the root object ID too, to disambiguate subvols */
2283         buf->f_fsid.val[0] ^=
2284                 BTRFS_I(d_inode(dentry))->root->root_key.objectid >> 32;
2285         buf->f_fsid.val[1] ^=
2286                 BTRFS_I(d_inode(dentry))->root->root_key.objectid;
2287
2288         return 0;
2289 }
2290
2291 static void btrfs_kill_super(struct super_block *sb)
2292 {
2293         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2294         kill_anon_super(sb);
2295         btrfs_free_fs_info(fs_info);
2296 }
2297
2298 static struct file_system_type btrfs_fs_type = {
2299         .owner          = THIS_MODULE,
2300         .name           = "btrfs",
2301         .mount          = btrfs_mount,
2302         .kill_sb        = btrfs_kill_super,
2303         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2304 };
2305
2306 static struct file_system_type btrfs_root_fs_type = {
2307         .owner          = THIS_MODULE,
2308         .name           = "btrfs",
2309         .mount          = btrfs_mount_root,
2310         .kill_sb        = btrfs_kill_super,
2311         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2312 };
2313
2314 MODULE_ALIAS_FS("btrfs");
2315
2316 static int btrfs_control_open(struct inode *inode, struct file *file)
2317 {
2318         /*
2319          * The control file's private_data is used to hold the
2320          * transaction when it is started and is used to keep
2321          * track of whether a transaction is already in progress.
2322          */
2323         file->private_data = NULL;
2324         return 0;
2325 }
2326
2327 /*
2328  * Used by /dev/btrfs-control for devices ioctls.
2329  */
2330 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
2331                                 unsigned long arg)
2332 {
2333         struct btrfs_ioctl_vol_args *vol;
2334         struct btrfs_device *device = NULL;
2335         int ret = -ENOTTY;
2336
2337         if (!capable(CAP_SYS_ADMIN))
2338                 return -EPERM;
2339
2340         vol = memdup_user((void __user *)arg, sizeof(*vol));
2341         if (IS_ERR(vol))
2342                 return PTR_ERR(vol);
2343         vol->name[BTRFS_PATH_NAME_MAX] = '\0';
2344
2345         switch (cmd) {
2346         case BTRFS_IOC_SCAN_DEV:
2347                 mutex_lock(&uuid_mutex);
2348                 device = btrfs_scan_one_device(vol->name, FMODE_READ,
2349                                                &btrfs_root_fs_type);
2350                 ret = PTR_ERR_OR_ZERO(device);
2351                 mutex_unlock(&uuid_mutex);
2352                 break;
2353         case BTRFS_IOC_FORGET_DEV:
2354                 ret = btrfs_forget_devices(vol->name);
2355                 break;
2356         case BTRFS_IOC_DEVICES_READY:
2357                 mutex_lock(&uuid_mutex);
2358                 device = btrfs_scan_one_device(vol->name, FMODE_READ,
2359                                                &btrfs_root_fs_type);
2360                 if (IS_ERR(device)) {
2361                         mutex_unlock(&uuid_mutex);
2362                         ret = PTR_ERR(device);
2363                         break;
2364                 }
2365                 ret = !(device->fs_devices->num_devices ==
2366                         device->fs_devices->total_devices);
2367                 mutex_unlock(&uuid_mutex);
2368                 break;
2369         case BTRFS_IOC_GET_SUPPORTED_FEATURES:
2370                 ret = btrfs_ioctl_get_supported_features((void __user*)arg);
2371                 break;
2372         }
2373
2374         kfree(vol);
2375         return ret;
2376 }
2377
2378 static int btrfs_freeze(struct super_block *sb)
2379 {
2380         struct btrfs_trans_handle *trans;
2381         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2382         struct btrfs_root *root = fs_info->tree_root;
2383
2384         set_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2385         /*
2386          * We don't need a barrier here, we'll wait for any transaction that
2387          * could be in progress on other threads (and do delayed iputs that
2388          * we want to avoid on a frozen filesystem), or do the commit
2389          * ourselves.
2390          */
2391         trans = btrfs_attach_transaction_barrier(root);
2392         if (IS_ERR(trans)) {
2393                 /* no transaction, don't bother */
2394                 if (PTR_ERR(trans) == -ENOENT)
2395                         return 0;
2396                 return PTR_ERR(trans);
2397         }
2398         return btrfs_commit_transaction(trans);
2399 }
2400
2401 static int btrfs_unfreeze(struct super_block *sb)
2402 {
2403         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2404
2405         clear_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2406         return 0;
2407 }
2408
2409 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
2410 {
2411         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
2412         struct btrfs_device *dev, *first_dev = NULL;
2413
2414         /*
2415          * Lightweight locking of the devices. We should not need
2416          * device_list_mutex here as we only read the device data and the list
2417          * is protected by RCU.  Even if a device is deleted during the list
2418          * traversals, we'll get valid data, the freeing callback will wait at
2419          * least until the rcu_read_unlock.
2420          */
2421         rcu_read_lock();
2422         list_for_each_entry_rcu(dev, &fs_info->fs_devices->devices, dev_list) {
2423                 if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state))
2424                         continue;
2425                 if (!dev->name)
2426                         continue;
2427                 if (!first_dev || dev->devid < first_dev->devid)
2428                         first_dev = dev;
2429         }
2430
2431         if (first_dev)
2432                 seq_escape(m, rcu_str_deref(first_dev->name), " \t\n\\");
2433         else
2434                 WARN_ON(1);
2435         rcu_read_unlock();
2436         return 0;
2437 }
2438
2439 static const struct super_operations btrfs_super_ops = {
2440         .drop_inode     = btrfs_drop_inode,
2441         .evict_inode    = btrfs_evict_inode,
2442         .put_super      = btrfs_put_super,
2443         .sync_fs        = btrfs_sync_fs,
2444         .show_options   = btrfs_show_options,
2445         .show_devname   = btrfs_show_devname,
2446         .alloc_inode    = btrfs_alloc_inode,
2447         .destroy_inode  = btrfs_destroy_inode,
2448         .free_inode     = btrfs_free_inode,
2449         .statfs         = btrfs_statfs,
2450         .remount_fs     = btrfs_remount,
2451         .freeze_fs      = btrfs_freeze,
2452         .unfreeze_fs    = btrfs_unfreeze,
2453 };
2454
2455 static const struct file_operations btrfs_ctl_fops = {
2456         .open = btrfs_control_open,
2457         .unlocked_ioctl  = btrfs_control_ioctl,
2458         .compat_ioctl = compat_ptr_ioctl,
2459         .owner   = THIS_MODULE,
2460         .llseek = noop_llseek,
2461 };
2462
2463 static struct miscdevice btrfs_misc = {
2464         .minor          = BTRFS_MINOR,
2465         .name           = "btrfs-control",
2466         .fops           = &btrfs_ctl_fops
2467 };
2468
2469 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2470 MODULE_ALIAS("devname:btrfs-control");
2471
2472 static int __init btrfs_interface_init(void)
2473 {
2474         return misc_register(&btrfs_misc);
2475 }
2476
2477 static __cold void btrfs_interface_exit(void)
2478 {
2479         misc_deregister(&btrfs_misc);
2480 }
2481
2482 static void __init btrfs_print_mod_info(void)
2483 {
2484         static const char options[] = ""
2485 #ifdef CONFIG_BTRFS_DEBUG
2486                         ", debug=on"
2487 #endif
2488 #ifdef CONFIG_BTRFS_ASSERT
2489                         ", assert=on"
2490 #endif
2491 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2492                         ", integrity-checker=on"
2493 #endif
2494 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
2495                         ", ref-verify=on"
2496 #endif
2497                         ;
2498         pr_info("Btrfs loaded, crc32c=%s%s\n", crc32c_impl(), options);
2499 }
2500
2501 static int __init init_btrfs_fs(void)
2502 {
2503         int err;
2504
2505         btrfs_props_init();
2506
2507         err = btrfs_init_sysfs();
2508         if (err)
2509                 return err;
2510
2511         btrfs_init_compress();
2512
2513         err = btrfs_init_cachep();
2514         if (err)
2515                 goto free_compress;
2516
2517         err = extent_io_init();
2518         if (err)
2519                 goto free_cachep;
2520
2521         err = extent_state_cache_init();
2522         if (err)
2523                 goto free_extent_io;
2524
2525         err = extent_map_init();
2526         if (err)
2527                 goto free_extent_state_cache;
2528
2529         err = ordered_data_init();
2530         if (err)
2531                 goto free_extent_map;
2532
2533         err = btrfs_delayed_inode_init();
2534         if (err)
2535                 goto free_ordered_data;
2536
2537         err = btrfs_auto_defrag_init();
2538         if (err)
2539                 goto free_delayed_inode;
2540
2541         err = btrfs_delayed_ref_init();
2542         if (err)
2543                 goto free_auto_defrag;
2544
2545         err = btrfs_prelim_ref_init();
2546         if (err)
2547                 goto free_delayed_ref;
2548
2549         err = btrfs_end_io_wq_init();
2550         if (err)
2551                 goto free_prelim_ref;
2552
2553         err = btrfs_interface_init();
2554         if (err)
2555                 goto free_end_io_wq;
2556
2557         btrfs_init_lockdep();
2558
2559         btrfs_print_mod_info();
2560
2561         err = btrfs_run_sanity_tests();
2562         if (err)
2563                 goto unregister_ioctl;
2564
2565         err = register_filesystem(&btrfs_fs_type);
2566         if (err)
2567                 goto unregister_ioctl;
2568
2569         return 0;
2570
2571 unregister_ioctl:
2572         btrfs_interface_exit();
2573 free_end_io_wq:
2574         btrfs_end_io_wq_exit();
2575 free_prelim_ref:
2576         btrfs_prelim_ref_exit();
2577 free_delayed_ref:
2578         btrfs_delayed_ref_exit();
2579 free_auto_defrag:
2580         btrfs_auto_defrag_exit();
2581 free_delayed_inode:
2582         btrfs_delayed_inode_exit();
2583 free_ordered_data:
2584         ordered_data_exit();
2585 free_extent_map:
2586         extent_map_exit();
2587 free_extent_state_cache:
2588         extent_state_cache_exit();
2589 free_extent_io:
2590         extent_io_exit();
2591 free_cachep:
2592         btrfs_destroy_cachep();
2593 free_compress:
2594         btrfs_exit_compress();
2595         btrfs_exit_sysfs();
2596
2597         return err;
2598 }
2599
2600 static void __exit exit_btrfs_fs(void)
2601 {
2602         btrfs_destroy_cachep();
2603         btrfs_delayed_ref_exit();
2604         btrfs_auto_defrag_exit();
2605         btrfs_delayed_inode_exit();
2606         btrfs_prelim_ref_exit();
2607         ordered_data_exit();
2608         extent_map_exit();
2609         extent_state_cache_exit();
2610         extent_io_exit();
2611         btrfs_interface_exit();
2612         btrfs_end_io_wq_exit();
2613         unregister_filesystem(&btrfs_fs_type);
2614         btrfs_exit_sysfs();
2615         btrfs_cleanup_fs_uuids();
2616         btrfs_exit_compress();
2617 }
2618
2619 late_initcall(init_btrfs_fs);
2620 module_exit(exit_btrfs_fs)
2621
2622 MODULE_LICENSE("GPL");
2623 MODULE_SOFTDEP("pre: crc32c");
2624 MODULE_SOFTDEP("pre: xxhash64");
2625 MODULE_SOFTDEP("pre: sha256");
2626 MODULE_SOFTDEP("pre: blake2b-256");