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 "zoned.h"
  48 #include "tests/btrfs-tests.h"
  49 #include "block-group.h"
  50 #include "discard.h"
  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         btrfs_set_sb_rdonly(sb);
 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                 if (fs_info)
 245                         printk("%sBTRFS %s (device %s): %pV\n", lvl, type,
 246                                 fs_info->sb->s_id, &vaf);
 247                 else
 248                         printk("%sBTRFS %s: %pV\n", lvl, type, &vaf);
 249         }
 250
 251         va_end(args);
 252 }
 253 #endif
 254
 255 #if BITS_PER_LONG == 32
 256 void __cold btrfs_warn_32bit_limit(struct btrfs_fs_info *fs_info)
 257 {
 258         if (!test_and_set_bit(BTRFS_FS_32BIT_WARN, &fs_info->flags)) {
 259                 btrfs_warn(fs_info, "reaching 32bit limit for logical addresses");
 260                 btrfs_warn(fs_info,
 261 "due to page cache limit on 32bit systems, btrfs can't access metadata at or beyond %lluT",
 262                            BTRFS_32BIT_MAX_FILE_SIZE >> 40);
 263                 btrfs_warn(fs_info,
 264                            "please consider upgrading to 64bit kernel/hardware");
 265         }
 266 }
 267
 268 void __cold btrfs_err_32bit_limit(struct btrfs_fs_info *fs_info)
 269 {
 270         if (!test_and_set_bit(BTRFS_FS_32BIT_ERROR, &fs_info->flags)) {
 271                 btrfs_err(fs_info, "reached 32bit limit for logical addresses");
 272                 btrfs_err(fs_info,
 273 "due to page cache limit on 32bit systems, metadata beyond %lluT can't be accessed",
 274                           BTRFS_32BIT_MAX_FILE_SIZE >> 40);
 275                 btrfs_err(fs_info,
 276                            "please consider upgrading to 64bit kernel/hardware");
 277         }
 278 }
 279 #endif
 280
 281 /*
 282  * We only mark the transaction aborted and then set the file system read-only.
 283  * This will prevent new transactions from starting or trying to join this
 284  * one.
 285  *
 286  * This means that error recovery at the call site is limited to freeing
 287  * any local memory allocations and passing the error code up without
 288  * further cleanup. The transaction should complete as it normally would
 289  * in the call path but will return -EIO.
 290  *
 291  * We'll complete the cleanup in btrfs_end_transaction and
 292  * btrfs_commit_transaction.
 293  */
 294 __cold
 295 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 296                                const char *function,
 297                                unsigned int line, int errno)
 298 {
 299         struct btrfs_fs_info *fs_info = trans->fs_info;
 300
 301         WRITE_ONCE(trans->aborted, errno);
 302         WRITE_ONCE(trans->transaction->aborted, errno);
 303         /* Wake up anybody who may be waiting on this transaction */
 304         wake_up(&fs_info->transaction_wait);
 305         wake_up(&fs_info->transaction_blocked_wait);
 306         __btrfs_handle_fs_error(fs_info, function, line, errno, NULL);
 307 }
 308 /*
 309  * __btrfs_panic decodes unexpected, fatal errors from the caller,
 310  * issues an alert, and either panics or BUGs, depending on mount options.
 311  */
 312 __cold
 313 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 314                    unsigned int line, int errno, const char *fmt, ...)
 315 {
 316         char *s_id = "<unknown>";
 317         const char *errstr;
 318         struct va_format vaf = { .fmt = fmt };
 319         va_list args;
 320
 321         if (fs_info)
 322                 s_id = fs_info->sb->s_id;
 323
 324         va_start(args, fmt);
 325         vaf.va = &args;
 326
 327         errstr = btrfs_decode_error(errno);
 328         if (fs_info && (btrfs_test_opt(fs_info, PANIC_ON_FATAL_ERROR)))
 329                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
 330                         s_id, function, line, &vaf, errno, errstr);
 331
 332         btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
 333                    function, line, &vaf, errno, errstr);
 334         va_end(args);
 335         /* Caller calls BUG() */
 336 }
 337
 338 static void btrfs_put_super(struct super_block *sb)
 339 {
 340         close_ctree(btrfs_sb(sb));
 341 }
 342
 343 enum {
 344         Opt_acl, Opt_noacl,
 345         Opt_clear_cache,
 346         Opt_commit_interval,
 347         Opt_compress,
 348         Opt_compress_force,
 349         Opt_compress_force_type,
 350         Opt_compress_type,
 351         Opt_degraded,
 352         Opt_device,
 353         Opt_fatal_errors,
 354         Opt_flushoncommit, Opt_noflushoncommit,
 355         Opt_max_inline,
 356         Opt_barrier, Opt_nobarrier,
 357         Opt_datacow, Opt_nodatacow,
 358         Opt_datasum, Opt_nodatasum,
 359         Opt_defrag, Opt_nodefrag,
 360         Opt_discard, Opt_nodiscard,
 361         Opt_discard_mode,
 362         Opt_norecovery,
 363         Opt_ratio,
 364         Opt_rescan_uuid_tree,
 365         Opt_skip_balance,
 366         Opt_space_cache, Opt_no_space_cache,
 367         Opt_space_cache_version,
 368         Opt_ssd, Opt_nossd,
 369         Opt_ssd_spread, Opt_nossd_spread,
 370         Opt_subvol,
 371         Opt_subvol_empty,
 372         Opt_subvolid,
 373         Opt_thread_pool,
 374         Opt_treelog, Opt_notreelog,
 375         Opt_user_subvol_rm_allowed,
 376
 377         /* Rescue options */
 378         Opt_rescue,
 379         Opt_usebackuproot,
 380         Opt_nologreplay,
 381         Opt_ignorebadroots,
 382         Opt_ignoredatacsums,
 383         Opt_rescue_all,
 384
 385         /* Deprecated options */
 386         Opt_recovery,
 387         Opt_inode_cache, Opt_noinode_cache,
 388
 389         /* Debugging options */
 390         Opt_check_integrity,
 391         Opt_check_integrity_including_extent_data,
 392         Opt_check_integrity_print_mask,
 393         Opt_enospc_debug, Opt_noenospc_debug,
 394 #ifdef CONFIG_BTRFS_DEBUG
 395         Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 396 #endif
 397 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 398         Opt_ref_verify,
 399 #endif
 400         Opt_err,
 401 };
 402
 403 static const match_table_t tokens = {
 404         {Opt_acl, "acl"},
 405         {Opt_noacl, "noacl"},
 406         {Opt_clear_cache, "clear_cache"},
 407         {Opt_commit_interval, "commit=%u"},
 408         {Opt_compress, "compress"},
 409         {Opt_compress_type, "compress=%s"},
 410         {Opt_compress_force, "compress-force"},
 411         {Opt_compress_force_type, "compress-force=%s"},
 412         {Opt_degraded, "degraded"},
 413         {Opt_device, "device=%s"},
 414         {Opt_fatal_errors, "fatal_errors=%s"},
 415         {Opt_flushoncommit, "flushoncommit"},
 416         {Opt_noflushoncommit, "noflushoncommit"},
 417         {Opt_inode_cache, "inode_cache"},
 418         {Opt_noinode_cache, "noinode_cache"},
 419         {Opt_max_inline, "max_inline=%s"},
 420         {Opt_barrier, "barrier"},
 421         {Opt_nobarrier, "nobarrier"},
 422         {Opt_datacow, "datacow"},
 423         {Opt_nodatacow, "nodatacow"},
 424         {Opt_datasum, "datasum"},
 425         {Opt_nodatasum, "nodatasum"},
 426         {Opt_defrag, "autodefrag"},
 427         {Opt_nodefrag, "noautodefrag"},
 428         {Opt_discard, "discard"},
 429         {Opt_discard_mode, "discard=%s"},
 430         {Opt_nodiscard, "nodiscard"},
 431         {Opt_norecovery, "norecovery"},
 432         {Opt_ratio, "metadata_ratio=%u"},
 433         {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
 434         {Opt_skip_balance, "skip_balance"},
 435         {Opt_space_cache, "space_cache"},
 436         {Opt_no_space_cache, "nospace_cache"},
 437         {Opt_space_cache_version, "space_cache=%s"},
 438         {Opt_ssd, "ssd"},
 439         {Opt_nossd, "nossd"},
 440         {Opt_ssd_spread, "ssd_spread"},
 441         {Opt_nossd_spread, "nossd_spread"},
 442         {Opt_subvol, "subvol=%s"},
 443         {Opt_subvol_empty, "subvol="},
 444         {Opt_subvolid, "subvolid=%s"},
 445         {Opt_thread_pool, "thread_pool=%u"},
 446         {Opt_treelog, "treelog"},
 447         {Opt_notreelog, "notreelog"},
 448         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 449
 450         /* Rescue options */
 451         {Opt_rescue, "rescue=%s"},
 452         /* Deprecated, with alias rescue=nologreplay */
 453         {Opt_nologreplay, "nologreplay"},
 454         /* Deprecated, with alias rescue=usebackuproot */
 455         {Opt_usebackuproot, "usebackuproot"},
 456
 457         /* Deprecated options */
 458         {Opt_recovery, "recovery"},
 459
 460         /* Debugging options */
 461         {Opt_check_integrity, "check_int"},
 462         {Opt_check_integrity_including_extent_data, "check_int_data"},
 463         {Opt_check_integrity_print_mask, "check_int_print_mask=%u"},
 464         {Opt_enospc_debug, "enospc_debug"},
 465         {Opt_noenospc_debug, "noenospc_debug"},
 466 #ifdef CONFIG_BTRFS_DEBUG
 467         {Opt_fragment_data, "fragment=data"},
 468         {Opt_fragment_metadata, "fragment=metadata"},
 469         {Opt_fragment_all, "fragment=all"},
 470 #endif
 471 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 472         {Opt_ref_verify, "ref_verify"},
 473 #endif
 474         {Opt_err, NULL},
 475 };
 476
 477 static const match_table_t rescue_tokens = {
 478         {Opt_usebackuproot, "usebackuproot"},
 479         {Opt_nologreplay, "nologreplay"},
 480         {Opt_ignorebadroots, "ignorebadroots"},
 481         {Opt_ignorebadroots, "ibadroots"},
 482         {Opt_ignoredatacsums, "ignoredatacsums"},
 483         {Opt_ignoredatacsums, "idatacsums"},
 484         {Opt_rescue_all, "all"},
 485         {Opt_err, NULL},
 486 };
 487
 488 static bool check_ro_option(struct btrfs_fs_info *fs_info, unsigned long opt,
 489                             const char *opt_name)
 490 {
 491         if (fs_info->mount_opt & opt) {
 492                 btrfs_err(fs_info, "%s must be used with ro mount option",
 493                           opt_name);
 494                 return true;
 495         }
 496         return false;
 497 }
 498
 499 static int parse_rescue_options(struct btrfs_fs_info *info, const char *options)
 500 {
 501         char *opts;
 502         char *orig;
 503         char *p;
 504         substring_t args[MAX_OPT_ARGS];
 505         int ret = 0;
 506
 507         opts = kstrdup(options, GFP_KERNEL);
 508         if (!opts)
 509                 return -ENOMEM;
 510         orig = opts;
 511
 512         while ((p = strsep(&opts, ":")) != NULL) {
 513                 int token;
 514
 515                 if (!*p)
 516                         continue;
 517                 token = match_token(p, rescue_tokens, args);
 518                 switch (token){
 519                 case Opt_usebackuproot:
 520                         btrfs_info(info,
 521                                    "trying to use backup root at mount time");
 522                         btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
 523                         break;
 524                 case Opt_nologreplay:
 525                         btrfs_set_and_info(info, NOLOGREPLAY,
 526                                            "disabling log replay at mount time");
 527                         break;
 528                 case Opt_ignorebadroots:
 529                         btrfs_set_and_info(info, IGNOREBADROOTS,
 530                                            "ignoring bad roots");
 531                         break;
 532                 case Opt_ignoredatacsums:
 533                         btrfs_set_and_info(info, IGNOREDATACSUMS,
 534                                            "ignoring data csums");
 535                         break;
 536                 case Opt_rescue_all:
 537                         btrfs_info(info, "enabling all of the rescue options");
 538                         btrfs_set_and_info(info, IGNOREDATACSUMS,
 539                                            "ignoring data csums");
 540                         btrfs_set_and_info(info, IGNOREBADROOTS,
 541                                            "ignoring bad roots");
 542                         btrfs_set_and_info(info, NOLOGREPLAY,
 543                                            "disabling log replay at mount time");
 544                         break;
 545                 case Opt_err:
 546                         btrfs_info(info, "unrecognized rescue option '%s'", p);
 547                         ret = -EINVAL;
 548                         goto out;
 549                 default:
 550                         break;
 551                 }
 552
 553         }
 554 out:
 555         kfree(orig);
 556         return ret;
 557 }
 558
 559 /*
 560  * Regular mount options parser.  Everything that is needed only when
 561  * reading in a new superblock is parsed here.
 562  * XXX JDM: This needs to be cleaned up for remount.
 563  */
 564 int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 565                         unsigned long new_flags)
 566 {
 567         substring_t args[MAX_OPT_ARGS];
 568         char *p, *num;
 569         int intarg;
 570         int ret = 0;
 571         char *compress_type;
 572         bool compress_force = false;
 573         enum btrfs_compression_type saved_compress_type;
 574         int saved_compress_level;
 575         bool saved_compress_force;
 576         int no_compress = 0;
 577         const bool remounting = test_bit(BTRFS_FS_STATE_REMOUNTING, &info->fs_state);
 578
 579         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
 580                 btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
 581         else if (btrfs_free_space_cache_v1_active(info)) {
 582                 if (btrfs_is_zoned(info)) {
 583                         btrfs_info(info,
 584                         "zoned: clearing existing space cache");
 585                         btrfs_set_super_cache_generation(info->super_copy, 0);
 586                 } else {
 587                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 588                 }
 589         }
 590
 591         /*
 592          * Even the options are empty, we still need to do extra check
 593          * against new flags
 594          */
 595         if (!options)
 596                 goto check;
 597
 598         while ((p = strsep(&options, ",")) != NULL) {
 599                 int token;
 600                 if (!*p)
 601                         continue;
 602
 603                 token = match_token(p, tokens, args);
 604                 switch (token) {
 605                 case Opt_degraded:
 606                         btrfs_info(info, "allowing degraded mounts");
 607                         btrfs_set_opt(info->mount_opt, DEGRADED);
 608                         break;
 609                 case Opt_subvol:
 610                 case Opt_subvol_empty:
 611                 case Opt_subvolid:
 612                 case Opt_device:
 613                         /*
 614                          * These are parsed by btrfs_parse_subvol_options or
 615                          * btrfs_parse_device_options and can be ignored here.
 616                          */
 617                         break;
 618                 case Opt_nodatasum:
 619                         btrfs_set_and_info(info, NODATASUM,
 620                                            "setting nodatasum");
 621                         break;
 622                 case Opt_datasum:
 623                         if (btrfs_test_opt(info, NODATASUM)) {
 624                                 if (btrfs_test_opt(info, NODATACOW))
 625                                         btrfs_info(info,
 626                                                    "setting datasum, datacow enabled");
 627                                 else
 628                                         btrfs_info(info, "setting datasum");
 629                         }
 630                         btrfs_clear_opt(info->mount_opt, NODATACOW);
 631                         btrfs_clear_opt(info->mount_opt, NODATASUM);
 632                         break;
 633                 case Opt_nodatacow:
 634                         if (!btrfs_test_opt(info, NODATACOW)) {
 635                                 if (!btrfs_test_opt(info, COMPRESS) ||
 636                                     !btrfs_test_opt(info, FORCE_COMPRESS)) {
 637                                         btrfs_info(info,
 638                                                    "setting nodatacow, compression disabled");
 639                                 } else {
 640                                         btrfs_info(info, "setting nodatacow");
 641                                 }
 642                         }
 643                         btrfs_clear_opt(info->mount_opt, COMPRESS);
 644                         btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 645                         btrfs_set_opt(info->mount_opt, NODATACOW);
 646                         btrfs_set_opt(info->mount_opt, NODATASUM);
 647                         break;
 648                 case Opt_datacow:
 649                         btrfs_clear_and_info(info, NODATACOW,
 650                                              "setting datacow");
 651                         break;
 652                 case Opt_compress_force:
 653                 case Opt_compress_force_type:
 654                         compress_force = true;
 655                         fallthrough;
 656                 case Opt_compress:
 657                 case Opt_compress_type:
 658                         saved_compress_type = btrfs_test_opt(info,
 659                                                              COMPRESS) ?
 660                                 info->compress_type : BTRFS_COMPRESS_NONE;
 661                         saved_compress_force =
 662                                 btrfs_test_opt(info, FORCE_COMPRESS);
 663                         saved_compress_level = info->compress_level;
 664                         if (token == Opt_compress ||
 665                             token == Opt_compress_force ||
 666                             strncmp(args[0].from, "zlib", 4) == 0) {
 667                                 compress_type = "zlib";
 668
 669                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 670                                 info->compress_level = BTRFS_ZLIB_DEFAULT_LEVEL;
 671                                 /*
 672                                  * args[0] contains uninitialized data since
 673                                  * for these tokens we don't expect any
 674                                  * parameter.
 675                                  */
 676                                 if (token != Opt_compress &&
 677                                     token != Opt_compress_force)
 678                                         info->compress_level =
 679                                           btrfs_compress_str2level(
 680                                                         BTRFS_COMPRESS_ZLIB,
 681                                                         args[0].from + 4);
 682                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 683                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 684                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 685                                 no_compress = 0;
 686                         } else if (strncmp(args[0].from, "lzo", 3) == 0) {
 687                                 compress_type = "lzo";
 688                                 info->compress_type = BTRFS_COMPRESS_LZO;
 689                                 info->compress_level = 0;
 690                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 691                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 692                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 693                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
 694                                 no_compress = 0;
 695                         } else if (strncmp(args[0].from, "zstd", 4) == 0) {
 696                                 compress_type = "zstd";
 697                                 info->compress_type = BTRFS_COMPRESS_ZSTD;
 698                                 info->compress_level =
 699                                         btrfs_compress_str2level(
 700                                                          BTRFS_COMPRESS_ZSTD,
 701                                                          args[0].from + 4);
 702                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 703                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 704                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 705                                 btrfs_set_fs_incompat(info, COMPRESS_ZSTD);
 706                                 no_compress = 0;
 707                         } else if (strncmp(args[0].from, "no", 2) == 0) {
 708                                 compress_type = "no";
 709                                 info->compress_level = 0;
 710                                 info->compress_type = 0;
 711                                 btrfs_clear_opt(info->mount_opt, COMPRESS);
 712                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 713                                 compress_force = false;
 714                                 no_compress++;
 715                         } else {
 716                                 btrfs_err(info, "unrecognized compression value %s",
 717                                           args[0].from);
 718                                 ret = -EINVAL;
 719                                 goto out;
 720                         }
 721
 722                         if (compress_force) {
 723                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 724                         } else {
 725                                 /*
 726                                  * If we remount from compress-force=xxx to
 727                                  * compress=xxx, we need clear FORCE_COMPRESS
 728                                  * flag, otherwise, there is no way for users
 729                                  * to disable forcible compression separately.
 730                                  */
 731                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 732                         }
 733                         if (no_compress == 1) {
 734                                 btrfs_info(info, "use no compression");
 735                         } else if ((info->compress_type != saved_compress_type) ||
 736                                    (compress_force != saved_compress_force) ||
 737                                    (info->compress_level != saved_compress_level)) {
 738                                 btrfs_info(info, "%s %s compression, level %d",
 739                                            (compress_force) ? "force" : "use",
 740                                            compress_type, info->compress_level);
 741                         }
 742                         compress_force = false;
 743                         break;
 744                 case Opt_ssd:
 745                         btrfs_set_and_info(info, SSD,
 746                                            "enabling ssd optimizations");
 747                         btrfs_clear_opt(info->mount_opt, NOSSD);
 748                         break;
 749                 case Opt_ssd_spread:
 750                         btrfs_set_and_info(info, SSD,
 751                                            "enabling ssd optimizations");
 752                         btrfs_set_and_info(info, SSD_SPREAD,
 753                                            "using spread ssd allocation scheme");
 754                         btrfs_clear_opt(info->mount_opt, NOSSD);
 755                         break;
 756                 case Opt_nossd:
 757                         btrfs_set_opt(info->mount_opt, NOSSD);
 758                         btrfs_clear_and_info(info, SSD,
 759                                              "not using ssd optimizations");
 760                         fallthrough;
 761                 case Opt_nossd_spread:
 762                         btrfs_clear_and_info(info, SSD_SPREAD,
 763                                              "not using spread ssd allocation scheme");
 764                         break;
 765                 case Opt_barrier:
 766                         btrfs_clear_and_info(info, NOBARRIER,
 767                                              "turning on barriers");
 768                         break;
 769                 case Opt_nobarrier:
 770                         btrfs_set_and_info(info, NOBARRIER,
 771                                            "turning off barriers");
 772                         break;
 773                 case Opt_thread_pool:
 774                         ret = match_int(&args[0], &intarg);
 775                         if (ret) {
 776                                 btrfs_err(info, "unrecognized thread_pool value %s",
 777                                           args[0].from);
 778                                 goto out;
 779                         } else if (intarg == 0) {
 780                                 btrfs_err(info, "invalid value 0 for thread_pool");
 781                                 ret = -EINVAL;
 782                                 goto out;
 783                         }
 784                         info->thread_pool_size = intarg;
 785                         break;
 786                 case Opt_max_inline:
 787                         num = match_strdup(&args[0]);
 788                         if (num) {
 789                                 info->max_inline = memparse(num, NULL);
 790                                 kfree(num);
 791
 792                                 if (info->max_inline) {
 793                                         info->max_inline = min_t(u64,
 794                                                 info->max_inline,
 795                                                 info->sectorsize);
 796                                 }
 797                                 btrfs_info(info, "max_inline at %llu",
 798                                            info->max_inline);
 799                         } else {
 800                                 ret = -ENOMEM;
 801                                 goto out;
 802                         }
 803                         break;
 804                 case Opt_acl:
 805 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 806                         info->sb->s_flags |= SB_POSIXACL;
 807                         break;
 808 #else
 809                         btrfs_err(info, "support for ACL not compiled in!");
 810                         ret = -EINVAL;
 811                         goto out;
 812 #endif
 813                 case Opt_noacl:
 814                         info->sb->s_flags &= ~SB_POSIXACL;
 815                         break;
 816                 case Opt_notreelog:
 817                         btrfs_set_and_info(info, NOTREELOG,
 818                                            "disabling tree log");
 819                         break;
 820                 case Opt_treelog:
 821                         btrfs_clear_and_info(info, NOTREELOG,
 822                                              "enabling tree log");
 823                         break;
 824                 case Opt_norecovery:
 825                 case Opt_nologreplay:
 826                         btrfs_warn(info,
 827                 "'nologreplay' is deprecated, use 'rescue=nologreplay' instead");
 828                         btrfs_set_and_info(info, NOLOGREPLAY,
 829                                            "disabling log replay at mount time");
 830                         break;
 831                 case Opt_flushoncommit:
 832                         btrfs_set_and_info(info, FLUSHONCOMMIT,
 833                                            "turning on flush-on-commit");
 834                         break;
 835                 case Opt_noflushoncommit:
 836                         btrfs_clear_and_info(info, FLUSHONCOMMIT,
 837                                              "turning off flush-on-commit");
 838                         break;
 839                 case Opt_ratio:
 840                         ret = match_int(&args[0], &intarg);
 841                         if (ret) {
 842                                 btrfs_err(info, "unrecognized metadata_ratio value %s",
 843                                           args[0].from);
 844                                 goto out;
 845                         }
 846                         info->metadata_ratio = intarg;
 847                         btrfs_info(info, "metadata ratio %u",
 848                                    info->metadata_ratio);
 849                         break;
 850                 case Opt_discard:
 851                 case Opt_discard_mode:
 852                         if (token == Opt_discard ||
 853                             strcmp(args[0].from, "sync") == 0) {
 854                                 btrfs_clear_opt(info->mount_opt, DISCARD_ASYNC);
 855                                 btrfs_set_and_info(info, DISCARD_SYNC,
 856                                                    "turning on sync discard");
 857                         } else if (strcmp(args[0].from, "async") == 0) {
 858                                 btrfs_clear_opt(info->mount_opt, DISCARD_SYNC);
 859                                 btrfs_set_and_info(info, DISCARD_ASYNC,
 860                                                    "turning on async discard");
 861                         } else {
 862                                 btrfs_err(info, "unrecognized discard mode value %s",
 863                                           args[0].from);
 864                                 ret = -EINVAL;
 865                                 goto out;
 866                         }
 867                         break;
 868                 case Opt_nodiscard:
 869                         btrfs_clear_and_info(info, DISCARD_SYNC,
 870                                              "turning off discard");
 871                         btrfs_clear_and_info(info, DISCARD_ASYNC,
 872                                              "turning off async discard");
 873                         break;
 874                 case Opt_space_cache:
 875                 case Opt_space_cache_version:
 876                         if (token == Opt_space_cache ||
 877                             strcmp(args[0].from, "v1") == 0) {
 878                                 btrfs_clear_opt(info->mount_opt,
 879                                                 FREE_SPACE_TREE);
 880                                 btrfs_set_and_info(info, SPACE_CACHE,
 881                                            "enabling disk space caching");
 882                         } else if (strcmp(args[0].from, "v2") == 0) {
 883                                 btrfs_clear_opt(info->mount_opt,
 884                                                 SPACE_CACHE);
 885                                 btrfs_set_and_info(info, FREE_SPACE_TREE,
 886                                                    "enabling free space tree");
 887                         } else {
 888                                 btrfs_err(info, "unrecognized space_cache value %s",
 889                                           args[0].from);
 890                                 ret = -EINVAL;
 891                                 goto out;
 892                         }
 893                         break;
 894                 case Opt_rescan_uuid_tree:
 895                         btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
 896                         break;
 897                 case Opt_no_space_cache:
 898                         if (btrfs_test_opt(info, SPACE_CACHE)) {
 899                                 btrfs_clear_and_info(info, SPACE_CACHE,
 900                                              "disabling disk space caching");
 901                         }
 902                         if (btrfs_test_opt(info, FREE_SPACE_TREE)) {
 903                                 btrfs_clear_and_info(info, FREE_SPACE_TREE,
 904                                              "disabling free space tree");
 905                         }
 906                         break;
 907                 case Opt_inode_cache:
 908                 case Opt_noinode_cache:
 909                         btrfs_warn(info,
 910         "the 'inode_cache' option is deprecated and has no effect since 5.11");
 911                         break;
 912                 case Opt_clear_cache:
 913                         btrfs_set_and_info(info, CLEAR_CACHE,
 914                                            "force clearing of disk cache");
 915                         break;
 916                 case Opt_user_subvol_rm_allowed:
 917                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 918                         break;
 919                 case Opt_enospc_debug:
 920                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 921                         break;
 922                 case Opt_noenospc_debug:
 923                         btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
 924                         break;
 925                 case Opt_defrag:
 926                         btrfs_set_and_info(info, AUTO_DEFRAG,
 927                                            "enabling auto defrag");
 928                         break;
 929                 case Opt_nodefrag:
 930                         btrfs_clear_and_info(info, AUTO_DEFRAG,
 931                                              "disabling auto defrag");
 932                         break;
 933                 case Opt_recovery:
 934                 case Opt_usebackuproot:
 935                         btrfs_warn(info,
 936                         "'%s' is deprecated, use 'rescue=usebackuproot' instead",
 937                                    token == Opt_recovery ? "recovery" :
 938                                    "usebackuproot");
 939                         btrfs_info(info,
 940                                    "trying to use backup root at mount time");
 941                         btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
 942                         break;
 943                 case Opt_skip_balance:
 944                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 945                         break;
 946 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 947                 case Opt_check_integrity_including_extent_data:
 948                         btrfs_info(info,
 949                                    "enabling check integrity including extent data");
 950                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY_DATA);
 951                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 952                         break;
 953                 case Opt_check_integrity:
 954                         btrfs_info(info, "enabling check integrity");
 955                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 956                         break;
 957                 case Opt_check_integrity_print_mask:
 958                         ret = match_int(&args[0], &intarg);
 959                         if (ret) {
 960                                 btrfs_err(info,
 961                                 "unrecognized check_integrity_print_mask value %s",
 962                                         args[0].from);
 963                                 goto out;
 964                         }
 965                         info->check_integrity_print_mask = intarg;
 966                         btrfs_info(info, "check_integrity_print_mask 0x%x",
 967                                    info->check_integrity_print_mask);
 968                         break;
 969 #else
 970                 case Opt_check_integrity_including_extent_data:
 971                 case Opt_check_integrity:
 972                 case Opt_check_integrity_print_mask:
 973                         btrfs_err(info,
 974                                   "support for check_integrity* not compiled in!");
 975                         ret = -EINVAL;
 976                         goto out;
 977 #endif
 978                 case Opt_fatal_errors:
 979                         if (strcmp(args[0].from, "panic") == 0) {
 980                                 btrfs_set_opt(info->mount_opt,
 981                                               PANIC_ON_FATAL_ERROR);
 982                         } else if (strcmp(args[0].from, "bug") == 0) {
 983                                 btrfs_clear_opt(info->mount_opt,
 984                                               PANIC_ON_FATAL_ERROR);
 985                         } else {
 986                                 btrfs_err(info, "unrecognized fatal_errors value %s",
 987                                           args[0].from);
 988                                 ret = -EINVAL;
 989                                 goto out;
 990                         }
 991                         break;
 992                 case Opt_commit_interval:
 993                         intarg = 0;
 994                         ret = match_int(&args[0], &intarg);
 995                         if (ret) {
 996                                 btrfs_err(info, "unrecognized commit_interval value %s",
 997                                           args[0].from);
 998                                 ret = -EINVAL;
 999                                 goto out;
1000                         }
1001                         if (intarg == 0) {
1002                                 btrfs_info(info,
1003                                            "using default commit interval %us",
1004                                            BTRFS_DEFAULT_COMMIT_INTERVAL);
1005                                 intarg = BTRFS_DEFAULT_COMMIT_INTERVAL;
1006                         } else if (intarg > 300) {
1007                                 btrfs_warn(info, "excessive commit interval %d",
1008                                            intarg);
1009                         }
1010                         info->commit_interval = intarg;
1011                         break;
1012                 case Opt_rescue:
1013                         ret = parse_rescue_options(info, args[0].from);
1014                         if (ret < 0) {
1015                                 btrfs_err(info, "unrecognized rescue value %s",
1016                                           args[0].from);
1017                                 goto out;
1018                         }
1019                         break;
1020 #ifdef CONFIG_BTRFS_DEBUG
1021                 case Opt_fragment_all:
1022                         btrfs_info(info, "fragmenting all space");
1023                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
1024                         btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
1025                         break;
1026                 case Opt_fragment_metadata:
1027                         btrfs_info(info, "fragmenting metadata");
1028                         btrfs_set_opt(info->mount_opt,
1029                                       FRAGMENT_METADATA);
1030                         break;
1031                 case Opt_fragment_data:
1032                         btrfs_info(info, "fragmenting data");
1033                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
1034                         break;
1035 #endif
1036 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
1037                 case Opt_ref_verify:
1038                         btrfs_info(info, "doing ref verification");
1039                         btrfs_set_opt(info->mount_opt, REF_VERIFY);
1040                         break;
1041 #endif
1042                 case Opt_err:
1043                         btrfs_err(info, "unrecognized mount option '%s'", p);
1044                         ret = -EINVAL;
1045                         goto out;
1046                 default:
1047                         break;
1048                 }
1049         }
1050 check:
1051         /* We're read-only, don't have to check. */
1052         if (new_flags & SB_RDONLY)
1053                 goto out;
1054
1055         if (check_ro_option(info, BTRFS_MOUNT_NOLOGREPLAY, "nologreplay") ||
1056             check_ro_option(info, BTRFS_MOUNT_IGNOREBADROOTS, "ignorebadroots") ||
1057             check_ro_option(info, BTRFS_MOUNT_IGNOREDATACSUMS, "ignoredatacsums"))
1058                 ret = -EINVAL;
1059 out:
1060         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) &&
1061             !btrfs_test_opt(info, FREE_SPACE_TREE) &&
1062             !btrfs_test_opt(info, CLEAR_CACHE)) {
1063                 btrfs_err(info, "cannot disable free space tree");
1064                 ret = -EINVAL;
1065
1066         }
1067         if (!ret)
1068                 ret = btrfs_check_mountopts_zoned(info);
1069         if (!ret && !remounting) {
1070                 if (btrfs_test_opt(info, SPACE_CACHE))
1071                         btrfs_info(info, "disk space caching is enabled");
1072                 if (btrfs_test_opt(info, FREE_SPACE_TREE))
1073                         btrfs_info(info, "using free space tree");
1074         }
1075         return ret;
1076 }
1077
1078 /*
1079  * Parse mount options that are required early in the mount process.
1080  *
1081  * All other options will be parsed on much later in the mount process and
1082  * only when we need to allocate a new super block.
1083  */
1084 static int btrfs_parse_device_options(const char *options, fmode_t flags,
1085                                       void *holder)
1086 {
1087         substring_t args[MAX_OPT_ARGS];
1088         char *device_name, *opts, *orig, *p;
1089         struct btrfs_device *device = NULL;
1090         int error = 0;
1091
1092         lockdep_assert_held(&uuid_mutex);
1093
1094         if (!options)
1095                 return 0;
1096
1097         /*
1098          * strsep changes the string, duplicate it because btrfs_parse_options
1099          * gets called later
1100          */
1101         opts = kstrdup(options, GFP_KERNEL);
1102         if (!opts)
1103                 return -ENOMEM;
1104         orig = opts;
1105
1106         while ((p = strsep(&opts, ",")) != NULL) {
1107                 int token;
1108
1109                 if (!*p)
1110                         continue;
1111
1112                 token = match_token(p, tokens, args);
1113                 if (token == Opt_device) {
1114                         device_name = match_strdup(&args[0]);
1115                         if (!device_name) {
1116                                 error = -ENOMEM;
1117                                 goto out;
1118                         }
1119                         device = btrfs_scan_one_device(device_name, flags,
1120                                         holder);
1121                         kfree(device_name);
1122                         if (IS_ERR(device)) {
1123                                 error = PTR_ERR(device);
1124                                 goto out;
1125                         }
1126                 }
1127         }
1128
1129 out:
1130         kfree(orig);
1131         return error;
1132 }
1133
1134 /*
1135  * Parse mount options that are related to subvolume id
1136  *
1137  * The value is later passed to mount_subvol()
1138  */
1139 static int btrfs_parse_subvol_options(const char *options, char **subvol_name,
1140                 u64 *subvol_objectid)
1141 {
1142         substring_t args[MAX_OPT_ARGS];
1143         char *opts, *orig, *p;
1144         int error = 0;
1145         u64 subvolid;
1146
1147         if (!options)
1148                 return 0;
1149
1150         /*
1151          * strsep changes the string, duplicate it because
1152          * btrfs_parse_device_options gets called later
1153          */
1154         opts = kstrdup(options, GFP_KERNEL);
1155         if (!opts)
1156                 return -ENOMEM;
1157         orig = opts;
1158
1159         while ((p = strsep(&opts, ",")) != NULL) {
1160                 int token;
1161                 if (!*p)
1162                         continue;
1163
1164                 token = match_token(p, tokens, args);
1165                 switch (token) {
1166                 case Opt_subvol:
1167                         kfree(*subvol_name);
1168                         *subvol_name = match_strdup(&args[0]);
1169                         if (!*subvol_name) {
1170                                 error = -ENOMEM;
1171                                 goto out;
1172                         }
1173                         break;
1174                 case Opt_subvolid:
1175                         error = match_u64(&args[0], &subvolid);
1176                         if (error)
1177                                 goto out;
1178
1179                         /* we want the original fs_tree */
1180                         if (subvolid == 0)
1181                                 subvolid = BTRFS_FS_TREE_OBJECTID;
1182
1183                         *subvol_objectid = subvolid;
1184                         break;
1185                 default:
1186                         break;
1187                 }
1188         }
1189
1190 out:
1191         kfree(orig);
1192         return error;
1193 }
1194
1195 char *btrfs_get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
1196                                           u64 subvol_objectid)
1197 {
1198         struct btrfs_root *root = fs_info->tree_root;
1199         struct btrfs_root *fs_root = NULL;
1200         struct btrfs_root_ref *root_ref;
1201         struct btrfs_inode_ref *inode_ref;
1202         struct btrfs_key key;
1203         struct btrfs_path *path = NULL;
1204         char *name = NULL, *ptr;
1205         u64 dirid;
1206         int len;
1207         int ret;
1208
1209         path = btrfs_alloc_path();
1210         if (!path) {
1211                 ret = -ENOMEM;
1212                 goto err;
1213         }
1214
1215         name = kmalloc(PATH_MAX, GFP_KERNEL);
1216         if (!name) {
1217                 ret = -ENOMEM;
1218                 goto err;
1219         }
1220         ptr = name + PATH_MAX - 1;
1221         ptr[0] = '\0';
1222
1223         /*
1224          * Walk up the subvolume trees in the tree of tree roots by root
1225          * backrefs until we hit the top-level subvolume.
1226          */
1227         while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
1228                 key.objectid = subvol_objectid;
1229                 key.type = BTRFS_ROOT_BACKREF_KEY;
1230                 key.offset = (u64)-1;
1231
1232                 ret = btrfs_search_backwards(root, &key, path);
1233                 if (ret < 0) {
1234                         goto err;
1235                 } else if (ret > 0) {
1236                         ret = -ENOENT;
1237                         goto err;
1238                 }
1239
1240                 subvol_objectid = key.offset;
1241
1242                 root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1243                                           struct btrfs_root_ref);
1244                 len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
1245                 ptr -= len + 1;
1246                 if (ptr < name) {
1247                         ret = -ENAMETOOLONG;
1248                         goto err;
1249                 }
1250                 read_extent_buffer(path->nodes[0], ptr + 1,
1251                                    (unsigned long)(root_ref + 1), len);
1252                 ptr[0] = '/';
1253                 dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
1254                 btrfs_release_path(path);
1255
1256                 fs_root = btrfs_get_fs_root(fs_info, subvol_objectid, true);
1257                 if (IS_ERR(fs_root)) {
1258                         ret = PTR_ERR(fs_root);
1259                         fs_root = NULL;
1260                         goto err;
1261                 }
1262
1263                 /*
1264                  * Walk up the filesystem tree by inode refs until we hit the
1265                  * root directory.
1266                  */
1267                 while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
1268                         key.objectid = dirid;
1269                         key.type = BTRFS_INODE_REF_KEY;
1270                         key.offset = (u64)-1;
1271
1272                         ret = btrfs_search_backwards(fs_root, &key, path);
1273                         if (ret < 0) {
1274                                 goto err;
1275                         } else if (ret > 0) {
1276                                 ret = -ENOENT;
1277                                 goto err;
1278                         }
1279
1280                         dirid = key.offset;
1281
1282                         inode_ref = btrfs_item_ptr(path->nodes[0],
1283                                                    path->slots[0],
1284                                                    struct btrfs_inode_ref);
1285                         len = btrfs_inode_ref_name_len(path->nodes[0],
1286                                                        inode_ref);
1287                         ptr -= len + 1;
1288                         if (ptr < name) {
1289                                 ret = -ENAMETOOLONG;
1290                                 goto err;
1291                         }
1292                         read_extent_buffer(path->nodes[0], ptr + 1,
1293                                            (unsigned long)(inode_ref + 1), len);
1294                         ptr[0] = '/';
1295                         btrfs_release_path(path);
1296                 }
1297                 btrfs_put_root(fs_root);
1298                 fs_root = NULL;
1299         }
1300
1301         btrfs_free_path(path);
1302         if (ptr == name + PATH_MAX - 1) {
1303                 name[0] = '/';
1304                 name[1] = '\0';
1305         } else {
1306                 memmove(name, ptr, name + PATH_MAX - ptr);
1307         }
1308         return name;
1309
1310 err:
1311         btrfs_put_root(fs_root);
1312         btrfs_free_path(path);
1313         kfree(name);
1314         return ERR_PTR(ret);
1315 }
1316
1317 static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
1318 {
1319         struct btrfs_root *root = fs_info->tree_root;
1320         struct btrfs_dir_item *di;
1321         struct btrfs_path *path;
1322         struct btrfs_key location;
1323         u64 dir_id;
1324
1325         path = btrfs_alloc_path();
1326         if (!path)
1327                 return -ENOMEM;
1328
1329         /*
1330          * Find the "default" dir item which points to the root item that we
1331          * will mount by default if we haven't been given a specific subvolume
1332          * to mount.
1333          */
1334         dir_id = btrfs_super_root_dir(fs_info->super_copy);
1335         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
1336         if (IS_ERR(di)) {
1337                 btrfs_free_path(path);
1338                 return PTR_ERR(di);
1339         }
1340         if (!di) {
1341                 /*
1342                  * Ok the default dir item isn't there.  This is weird since
1343                  * it's always been there, but don't freak out, just try and
1344                  * mount the top-level subvolume.
1345                  */
1346                 btrfs_free_path(path);
1347                 *objectid = BTRFS_FS_TREE_OBJECTID;
1348                 return 0;
1349         }
1350
1351         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
1352         btrfs_free_path(path);
1353         *objectid = location.objectid;
1354         return 0;
1355 }
1356
1357 static int btrfs_fill_super(struct super_block *sb,
1358                             struct btrfs_fs_devices *fs_devices,
1359                             void *data)
1360 {
1361         struct inode *inode;
1362         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1363         int err;
1364
1365         sb->s_maxbytes = MAX_LFS_FILESIZE;
1366         sb->s_magic = BTRFS_SUPER_MAGIC;
1367         sb->s_op = &btrfs_super_ops;
1368         sb->s_d_op = &btrfs_dentry_operations;
1369         sb->s_export_op = &btrfs_export_ops;
1370 #ifdef CONFIG_FS_VERITY
1371         sb->s_vop = &btrfs_verityops;
1372 #endif
1373         sb->s_xattr = btrfs_xattr_handlers;
1374         sb->s_time_gran = 1;
1375 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
1376         sb->s_flags |= SB_POSIXACL;
1377 #endif
1378         sb->s_flags |= SB_I_VERSION;
1379         sb->s_iflags |= SB_I_CGROUPWB;
1380
1381         err = super_setup_bdi(sb);
1382         if (err) {
1383                 btrfs_err(fs_info, "super_setup_bdi failed");
1384                 return err;
1385         }
1386
1387         err = open_ctree(sb, fs_devices, (char *)data);
1388         if (err) {
1389                 btrfs_err(fs_info, "open_ctree failed");
1390                 return err;
1391         }
1392
1393         inode = btrfs_iget(sb, BTRFS_FIRST_FREE_OBJECTID, fs_info->fs_root);
1394         if (IS_ERR(inode)) {
1395                 err = PTR_ERR(inode);
1396                 goto fail_close;
1397         }
1398
1399         sb->s_root = d_make_root(inode);
1400         if (!sb->s_root) {
1401                 err = -ENOMEM;
1402                 goto fail_close;
1403         }
1404
1405         cleancache_init_fs(sb);
1406         sb->s_flags |= SB_ACTIVE;
1407         return 0;
1408
1409 fail_close:
1410         close_ctree(fs_info);
1411         return err;
1412 }
1413
1414 int btrfs_sync_fs(struct super_block *sb, int wait)
1415 {
1416         struct btrfs_trans_handle *trans;
1417         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1418         struct btrfs_root *root = fs_info->tree_root;
1419
1420         trace_btrfs_sync_fs(fs_info, wait);
1421
1422         if (!wait) {
1423                 filemap_flush(fs_info->btree_inode->i_mapping);
1424                 return 0;
1425         }
1426
1427         btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
1428
1429         trans = btrfs_attach_transaction_barrier(root);
1430         if (IS_ERR(trans)) {
1431                 /* no transaction, don't bother */
1432                 if (PTR_ERR(trans) == -ENOENT) {
1433                         /*
1434                          * Exit unless we have some pending changes
1435                          * that need to go through commit
1436                          */
1437                         if (fs_info->pending_changes == 0)
1438                                 return 0;
1439                         /*
1440                          * A non-blocking test if the fs is frozen. We must not
1441                          * start a new transaction here otherwise a deadlock
1442                          * happens. The pending operations are delayed to the
1443                          * next commit after thawing.
1444                          */
1445                         if (sb_start_write_trylock(sb))
1446                                 sb_end_write(sb);
1447                         else
1448                                 return 0;
1449                         trans = btrfs_start_transaction(root, 0);
1450                 }
1451                 if (IS_ERR(trans))
1452                         return PTR_ERR(trans);
1453         }
1454         return btrfs_commit_transaction(trans);
1455 }
1456
1457 static void print_rescue_option(struct seq_file *seq, const char *s, bool *printed)
1458 {
1459         seq_printf(seq, "%s%s", (*printed) ? ":" : ",rescue=", s);
1460         *printed = true;
1461 }
1462
1463 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1464 {
1465         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1466         const char *compress_type;
1467         const char *subvol_name;
1468         bool printed = false;
1469
1470         if (btrfs_test_opt(info, DEGRADED))
1471                 seq_puts(seq, ",degraded");
1472         if (btrfs_test_opt(info, NODATASUM))
1473                 seq_puts(seq, ",nodatasum");
1474         if (btrfs_test_opt(info, NODATACOW))
1475                 seq_puts(seq, ",nodatacow");
1476         if (btrfs_test_opt(info, NOBARRIER))
1477                 seq_puts(seq, ",nobarrier");
1478         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1479                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
1480         if (info->thread_pool_size !=  min_t(unsigned long,
1481                                              num_online_cpus() + 2, 8))
1482                 seq_printf(seq, ",thread_pool=%u", info->thread_pool_size);
1483         if (btrfs_test_opt(info, COMPRESS)) {
1484                 compress_type = btrfs_compress_type2str(info->compress_type);
1485                 if (btrfs_test_opt(info, FORCE_COMPRESS))
1486                         seq_printf(seq, ",compress-force=%s", compress_type);
1487                 else
1488                         seq_printf(seq, ",compress=%s", compress_type);
1489                 if (info->compress_level)
1490                         seq_printf(seq, ":%d", info->compress_level);
1491         }
1492         if (btrfs_test_opt(info, NOSSD))
1493                 seq_puts(seq, ",nossd");
1494         if (btrfs_test_opt(info, SSD_SPREAD))
1495                 seq_puts(seq, ",ssd_spread");
1496         else if (btrfs_test_opt(info, SSD))
1497                 seq_puts(seq, ",ssd");
1498         if (btrfs_test_opt(info, NOTREELOG))
1499                 seq_puts(seq, ",notreelog");
1500         if (btrfs_test_opt(info, NOLOGREPLAY))
1501                 print_rescue_option(seq, "nologreplay", &printed);
1502         if (btrfs_test_opt(info, USEBACKUPROOT))
1503                 print_rescue_option(seq, "usebackuproot", &printed);
1504         if (btrfs_test_opt(info, IGNOREBADROOTS))
1505                 print_rescue_option(seq, "ignorebadroots", &printed);
1506         if (btrfs_test_opt(info, IGNOREDATACSUMS))
1507                 print_rescue_option(seq, "ignoredatacsums", &printed);
1508         if (btrfs_test_opt(info, FLUSHONCOMMIT))
1509                 seq_puts(seq, ",flushoncommit");
1510         if (btrfs_test_opt(info, DISCARD_SYNC))
1511                 seq_puts(seq, ",discard");
1512         if (btrfs_test_opt(info, DISCARD_ASYNC))
1513                 seq_puts(seq, ",discard=async");
1514         if (!(info->sb->s_flags & SB_POSIXACL))
1515                 seq_puts(seq, ",noacl");
1516         if (btrfs_free_space_cache_v1_active(info))
1517                 seq_puts(seq, ",space_cache");
1518         else if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
1519                 seq_puts(seq, ",space_cache=v2");
1520         else
1521                 seq_puts(seq, ",nospace_cache");
1522         if (btrfs_test_opt(info, RESCAN_UUID_TREE))
1523                 seq_puts(seq, ",rescan_uuid_tree");
1524         if (btrfs_test_opt(info, CLEAR_CACHE))
1525                 seq_puts(seq, ",clear_cache");
1526         if (btrfs_test_opt(info, USER_SUBVOL_RM_ALLOWED))
1527                 seq_puts(seq, ",user_subvol_rm_allowed");
1528         if (btrfs_test_opt(info, ENOSPC_DEBUG))
1529                 seq_puts(seq, ",enospc_debug");
1530         if (btrfs_test_opt(info, AUTO_DEFRAG))
1531                 seq_puts(seq, ",autodefrag");
1532         if (btrfs_test_opt(info, SKIP_BALANCE))
1533                 seq_puts(seq, ",skip_balance");
1534 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1535         if (btrfs_test_opt(info, CHECK_INTEGRITY_DATA))
1536                 seq_puts(seq, ",check_int_data");
1537         else if (btrfs_test_opt(info, CHECK_INTEGRITY))
1538                 seq_puts(seq, ",check_int");
1539         if (info->check_integrity_print_mask)
1540                 seq_printf(seq, ",check_int_print_mask=%d",
1541                                 info->check_integrity_print_mask);
1542 #endif
1543         if (info->metadata_ratio)
1544                 seq_printf(seq, ",metadata_ratio=%u", info->metadata_ratio);
1545         if (btrfs_test_opt(info, PANIC_ON_FATAL_ERROR))
1546                 seq_puts(seq, ",fatal_errors=panic");
1547         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1548                 seq_printf(seq, ",commit=%u", info->commit_interval);
1549 #ifdef CONFIG_BTRFS_DEBUG
1550         if (btrfs_test_opt(info, FRAGMENT_DATA))
1551                 seq_puts(seq, ",fragment=data");
1552         if (btrfs_test_opt(info, FRAGMENT_METADATA))
1553                 seq_puts(seq, ",fragment=metadata");
1554 #endif
1555         if (btrfs_test_opt(info, REF_VERIFY))
1556                 seq_puts(seq, ",ref_verify");
1557         seq_printf(seq, ",subvolid=%llu",
1558                   BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1559         subvol_name = btrfs_get_subvol_name_from_objectid(info,
1560                         BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1561         if (!IS_ERR(subvol_name)) {
1562                 seq_puts(seq, ",subvol=");
1563                 seq_escape(seq, subvol_name, " \t\n\\");
1564                 kfree(subvol_name);
1565         }
1566         return 0;
1567 }
1568
1569 static int btrfs_test_super(struct super_block *s, void *data)
1570 {
1571         struct btrfs_fs_info *p = data;
1572         struct btrfs_fs_info *fs_info = btrfs_sb(s);
1573
1574         return fs_info->fs_devices == p->fs_devices;
1575 }
1576
1577 static int btrfs_set_super(struct super_block *s, void *data)
1578 {
1579         int err = set_anon_super(s, data);
1580         if (!err)
1581                 s->s_fs_info = data;
1582         return err;
1583 }
1584
1585 /*
1586  * subvolumes are identified by ino 256
1587  */
1588 static inline int is_subvolume_inode(struct inode *inode)
1589 {
1590         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1591                 return 1;
1592         return 0;
1593 }
1594
1595 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
1596                                    struct vfsmount *mnt)
1597 {
1598         struct dentry *root;
1599         int ret;
1600
1601         if (!subvol_name) {
1602                 if (!subvol_objectid) {
1603                         ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
1604                                                           &subvol_objectid);
1605                         if (ret) {
1606                                 root = ERR_PTR(ret);
1607                                 goto out;
1608                         }
1609                 }
1610                 subvol_name = btrfs_get_subvol_name_from_objectid(
1611                                         btrfs_sb(mnt->mnt_sb), subvol_objectid);
1612                 if (IS_ERR(subvol_name)) {
1613                         root = ERR_CAST(subvol_name);
1614                         subvol_name = NULL;
1615                         goto out;
1616                 }
1617
1618         }
1619
1620         root = mount_subtree(mnt, subvol_name);
1621         /* mount_subtree() drops our reference on the vfsmount. */
1622         mnt = NULL;
1623
1624         if (!IS_ERR(root)) {
1625                 struct super_block *s = root->d_sb;
1626                 struct btrfs_fs_info *fs_info = btrfs_sb(s);
1627                 struct inode *root_inode = d_inode(root);
1628                 u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
1629
1630                 ret = 0;
1631                 if (!is_subvolume_inode(root_inode)) {
1632                         btrfs_err(fs_info, "'%s' is not a valid subvolume",
1633                                subvol_name);
1634                         ret = -EINVAL;
1635                 }
1636                 if (subvol_objectid && root_objectid != subvol_objectid) {
1637                         /*
1638                          * This will also catch a race condition where a
1639                          * subvolume which was passed by ID is renamed and
1640                          * another subvolume is renamed over the old location.
1641                          */
1642                         btrfs_err(fs_info,
1643                                   "subvol '%s' does not match subvolid %llu",
1644                                   subvol_name, subvol_objectid);
1645                         ret = -EINVAL;
1646                 }
1647                 if (ret) {
1648                         dput(root);
1649                         root = ERR_PTR(ret);
1650                         deactivate_locked_super(s);
1651                 }
1652         }
1653
1654 out:
1655         mntput(mnt);
1656         kfree(subvol_name);
1657         return root;
1658 }
1659
1660 /*
1661  * Find a superblock for the given device / mount point.
1662  *
1663  * Note: This is based on mount_bdev from fs/super.c with a few additions
1664  *       for multiple device setup.  Make sure to keep it in sync.
1665  */
1666 static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
1667                 int flags, const char *device_name, void *data)
1668 {
1669         struct block_device *bdev = NULL;
1670         struct super_block *s;
1671         struct btrfs_device *device = NULL;
1672         struct btrfs_fs_devices *fs_devices = NULL;
1673         struct btrfs_fs_info *fs_info = NULL;
1674         void *new_sec_opts = NULL;
1675         fmode_t mode = FMODE_READ;
1676         int error = 0;
1677
1678         if (!(flags & SB_RDONLY))
1679                 mode |= FMODE_WRITE;
1680
1681         if (data) {
1682                 error = security_sb_eat_lsm_opts(data, &new_sec_opts);
1683                 if (error)
1684                         return ERR_PTR(error);
1685         }
1686
1687         /*
1688          * Setup a dummy root and fs_info for test/set super.  This is because
1689          * we don't actually fill this stuff out until open_ctree, but we need
1690          * then open_ctree will properly initialize the file system specific
1691          * settings later.  btrfs_init_fs_info initializes the static elements
1692          * of the fs_info (locks and such) to make cleanup easier if we find a
1693          * superblock with our given fs_devices later on at sget() time.
1694          */
1695         fs_info = kvzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
1696         if (!fs_info) {
1697                 error = -ENOMEM;
1698                 goto error_sec_opts;
1699         }
1700         btrfs_init_fs_info(fs_info);
1701
1702         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1703         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
1704         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1705                 error = -ENOMEM;
1706                 goto error_fs_info;
1707         }
1708
1709         mutex_lock(&uuid_mutex);
1710         error = btrfs_parse_device_options(data, mode, fs_type);
1711         if (error) {
1712                 mutex_unlock(&uuid_mutex);
1713                 goto error_fs_info;
1714         }
1715
1716         device = btrfs_scan_one_device(device_name, mode, fs_type);
1717         if (IS_ERR(device)) {
1718                 mutex_unlock(&uuid_mutex);
1719                 error = PTR_ERR(device);
1720                 goto error_fs_info;
1721         }
1722
1723         fs_devices = device->fs_devices;
1724         fs_info->fs_devices = fs_devices;
1725
1726         error = btrfs_open_devices(fs_devices, mode, fs_type);
1727         mutex_unlock(&uuid_mutex);
1728         if (error)
1729                 goto error_fs_info;
1730
1731         if (!(flags & SB_RDONLY) && fs_devices->rw_devices == 0) {
1732                 error = -EACCES;
1733                 goto error_close_devices;
1734         }
1735
1736         bdev = fs_devices->latest_dev->bdev;
1737         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | SB_NOSEC,
1738                  fs_info);
1739         if (IS_ERR(s)) {
1740                 error = PTR_ERR(s);
1741                 goto error_close_devices;
1742         }
1743
1744         if (s->s_root) {
1745                 btrfs_close_devices(fs_devices);
1746                 btrfs_free_fs_info(fs_info);
1747                 if ((flags ^ s->s_flags) & SB_RDONLY)
1748                         error = -EBUSY;
1749         } else {
1750                 snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
1751                 btrfs_sb(s)->bdev_holder = fs_type;
1752                 if (!strstr(crc32c_impl(), "generic"))
1753                         set_bit(BTRFS_FS_CSUM_IMPL_FAST, &fs_info->flags);
1754                 error = btrfs_fill_super(s, fs_devices, data);
1755         }
1756         if (!error)
1757                 error = security_sb_set_mnt_opts(s, new_sec_opts, 0, NULL);
1758         security_free_mnt_opts(&new_sec_opts);
1759         if (error) {
1760                 deactivate_locked_super(s);
1761                 return ERR_PTR(error);
1762         }
1763
1764         return dget(s->s_root);
1765
1766 error_close_devices:
1767         btrfs_close_devices(fs_devices);
1768 error_fs_info:
1769         btrfs_free_fs_info(fs_info);
1770 error_sec_opts:
1771         security_free_mnt_opts(&new_sec_opts);
1772         return ERR_PTR(error);
1773 }
1774
1775 /*
1776  * Mount function which is called by VFS layer.
1777  *
1778  * In order to allow mounting a subvolume directly, btrfs uses mount_subtree()
1779  * which needs vfsmount* of device's root (/).  This means device's root has to
1780  * be mounted internally in any case.
1781  *
1782  * Operation flow:
1783  *   1. Parse subvol id related options for later use in mount_subvol().
1784  *
1785  *   2. Mount device's root (/) by calling vfs_kern_mount().
1786  *
1787  *      NOTE: vfs_kern_mount() is used by VFS to call btrfs_mount() in the
1788  *      first place. In order to avoid calling btrfs_mount() again, we use
1789  *      different file_system_type which is not registered to VFS by
1790  *      register_filesystem() (btrfs_root_fs_type). As a result,
1791  *      btrfs_mount_root() is called. The return value will be used by
1792  *      mount_subtree() in mount_subvol().
1793  *
1794  *   3. Call mount_subvol() to get the dentry of subvolume. Since there is
1795  *      "btrfs subvolume set-default", mount_subvol() is called always.
1796  */
1797 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1798                 const char *device_name, void *data)
1799 {
1800         struct vfsmount *mnt_root;
1801         struct dentry *root;
1802         char *subvol_name = NULL;
1803         u64 subvol_objectid = 0;
1804         int error = 0;
1805
1806         error = btrfs_parse_subvol_options(data, &subvol_name,
1807                                         &subvol_objectid);
1808         if (error) {
1809                 kfree(subvol_name);
1810                 return ERR_PTR(error);
1811         }
1812
1813         /* mount device's root (/) */
1814         mnt_root = vfs_kern_mount(&btrfs_root_fs_type, flags, device_name, data);
1815         if (PTR_ERR_OR_ZERO(mnt_root) == -EBUSY) {
1816                 if (flags & SB_RDONLY) {
1817                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1818                                 flags & ~SB_RDONLY, device_name, data);
1819                 } else {
1820                         mnt_root = vfs_kern_mount(&btrfs_root_fs_type,
1821                                 flags | SB_RDONLY, device_name, data);
1822                         if (IS_ERR(mnt_root)) {
1823                                 root = ERR_CAST(mnt_root);
1824                                 kfree(subvol_name);
1825                                 goto out;
1826                         }
1827
1828                         down_write(&mnt_root->mnt_sb->s_umount);
1829                         error = btrfs_remount(mnt_root->mnt_sb, &flags, NULL);
1830                         up_write(&mnt_root->mnt_sb->s_umount);
1831                         if (error < 0) {
1832                                 root = ERR_PTR(error);
1833                                 mntput(mnt_root);
1834                                 kfree(subvol_name);
1835                                 goto out;
1836                         }
1837                 }
1838         }
1839         if (IS_ERR(mnt_root)) {
1840                 root = ERR_CAST(mnt_root);
1841                 kfree(subvol_name);
1842                 goto out;
1843         }
1844
1845         /* mount_subvol() will free subvol_name and mnt_root */
1846         root = mount_subvol(subvol_name, subvol_objectid, mnt_root);
1847
1848 out:
1849         return root;
1850 }
1851
1852 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1853                                      u32 new_pool_size, u32 old_pool_size)
1854 {
1855         if (new_pool_size == old_pool_size)
1856                 return;
1857
1858         fs_info->thread_pool_size = new_pool_size;
1859
1860         btrfs_info(fs_info, "resize thread pool %d -> %d",
1861                old_pool_size, new_pool_size);
1862
1863         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1864         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1865         btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1866         btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
1867         btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
1868         btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
1869                                 new_pool_size);
1870         btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1871         btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1872         btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1873         btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
1874         btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
1875                                 new_pool_size);
1876 }
1877
1878 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1879                                        unsigned long old_opts, int flags)
1880 {
1881         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1882             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1883              (flags & SB_RDONLY))) {
1884                 /* wait for any defraggers to finish */
1885                 wait_event(fs_info->transaction_wait,
1886                            (atomic_read(&fs_info->defrag_running) == 0));
1887                 if (flags & SB_RDONLY)
1888                         sync_filesystem(fs_info->sb);
1889         }
1890 }
1891
1892 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1893                                          unsigned long old_opts)
1894 {
1895         const bool cache_opt = btrfs_test_opt(fs_info, SPACE_CACHE);
1896
1897         /*
1898          * We need to cleanup all defragable inodes if the autodefragment is
1899          * close or the filesystem is read only.
1900          */
1901         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1902             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) || sb_rdonly(fs_info->sb))) {
1903                 btrfs_cleanup_defrag_inodes(fs_info);
1904         }
1905
1906         /* If we toggled discard async */
1907         if (!btrfs_raw_test_opt(old_opts, DISCARD_ASYNC) &&
1908             btrfs_test_opt(fs_info, DISCARD_ASYNC))
1909                 btrfs_discard_resume(fs_info);
1910         else if (btrfs_raw_test_opt(old_opts, DISCARD_ASYNC) &&
1911                  !btrfs_test_opt(fs_info, DISCARD_ASYNC))
1912                 btrfs_discard_cleanup(fs_info);
1913
1914         /* If we toggled space cache */
1915         if (cache_opt != btrfs_free_space_cache_v1_active(fs_info))
1916                 btrfs_set_free_space_cache_v1_active(fs_info, cache_opt);
1917 }
1918
1919 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1920 {
1921         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1922         unsigned old_flags = sb->s_flags;
1923         unsigned long old_opts = fs_info->mount_opt;
1924         unsigned long old_compress_type = fs_info->compress_type;
1925         u64 old_max_inline = fs_info->max_inline;
1926         u32 old_thread_pool_size = fs_info->thread_pool_size;
1927         u32 old_metadata_ratio = fs_info->metadata_ratio;
1928         int ret;
1929
1930         sync_filesystem(sb);
1931         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1932
1933         if (data) {
1934                 void *new_sec_opts = NULL;
1935
1936                 ret = security_sb_eat_lsm_opts(data, &new_sec_opts);
1937                 if (!ret)
1938                         ret = security_sb_remount(sb, new_sec_opts);
1939                 security_free_mnt_opts(&new_sec_opts);
1940                 if (ret)
1941                         goto restore;
1942         }
1943
1944         ret = btrfs_parse_options(fs_info, data, *flags);
1945         if (ret)
1946                 goto restore;
1947
1948         /* V1 cache is not supported for subpage mount. */
1949         if (fs_info->sectorsize < PAGE_SIZE && btrfs_test_opt(fs_info, SPACE_CACHE)) {
1950                 btrfs_warn(fs_info,
1951         "v1 space cache is not supported for page size %lu with sectorsize %u",
1952                            PAGE_SIZE, fs_info->sectorsize);
1953                 ret = -EINVAL;
1954                 goto restore;
1955         }
1956         btrfs_remount_begin(fs_info, old_opts, *flags);
1957         btrfs_resize_thread_pool(fs_info,
1958                 fs_info->thread_pool_size, old_thread_pool_size);
1959
1960         if ((bool)btrfs_test_opt(fs_info, FREE_SPACE_TREE) !=
1961             (bool)btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE) &&
1962             (!sb_rdonly(sb) || (*flags & SB_RDONLY))) {
1963                 btrfs_warn(fs_info,
1964                 "remount supports changing free space tree only from ro to rw");
1965                 /* Make sure free space cache options match the state on disk */
1966                 if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
1967                         btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
1968                         btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
1969                 }
1970                 if (btrfs_free_space_cache_v1_active(fs_info)) {
1971                         btrfs_clear_opt(fs_info->mount_opt, FREE_SPACE_TREE);
1972                         btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE);
1973                 }
1974         }
1975
1976         if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
1977                 goto out;
1978
1979         if (*flags & SB_RDONLY) {
1980                 /*
1981                  * this also happens on 'umount -rf' or on shutdown, when
1982                  * the filesystem is busy.
1983                  */
1984                 cancel_work_sync(&fs_info->async_reclaim_work);
1985                 cancel_work_sync(&fs_info->async_data_reclaim_work);
1986
1987                 btrfs_discard_cleanup(fs_info);
1988
1989                 /* wait for the uuid_scan task to finish */
1990                 down(&fs_info->uuid_tree_rescan_sem);
1991                 /* avoid complains from lockdep et al. */
1992                 up(&fs_info->uuid_tree_rescan_sem);
1993
1994                 btrfs_set_sb_rdonly(sb);
1995
1996                 /*
1997                  * Setting SB_RDONLY will put the cleaner thread to
1998                  * sleep at the next loop if it's already active.
1999                  * If it's already asleep, we'll leave unused block
2000                  * groups on disk until we're mounted read-write again
2001                  * unless we clean them up here.
2002                  */
2003                 btrfs_delete_unused_bgs(fs_info);
2004
2005                 /*
2006                  * The cleaner task could be already running before we set the
2007                  * flag BTRFS_FS_STATE_RO (and SB_RDONLY in the superblock).
2008                  * We must make sure that after we finish the remount, i.e. after
2009                  * we call btrfs_commit_super(), the cleaner can no longer start
2010                  * a transaction - either because it was dropping a dead root,
2011                  * running delayed iputs or deleting an unused block group (the
2012                  * cleaner picked a block group from the list of unused block
2013                  * groups before we were able to in the previous call to
2014                  * btrfs_delete_unused_bgs()).
2015                  */
2016                 wait_on_bit(&fs_info->flags, BTRFS_FS_CLEANER_RUNNING,
2017                             TASK_UNINTERRUPTIBLE);
2018
2019                 /*
2020                  * We've set the superblock to RO mode, so we might have made
2021                  * the cleaner task sleep without running all pending delayed
2022                  * iputs. Go through all the delayed iputs here, so that if an
2023                  * unmount happens without remounting RW we don't end up at
2024                  * finishing close_ctree() with a non-empty list of delayed
2025                  * iputs.
2026                  */
2027                 btrfs_run_delayed_iputs(fs_info);
2028
2029                 btrfs_dev_replace_suspend_for_unmount(fs_info);
2030                 btrfs_scrub_cancel(fs_info);
2031                 btrfs_pause_balance(fs_info);
2032
2033                 /*
2034                  * Pause the qgroup rescan worker if it is running. We don't want
2035                  * it to be still running after we are in RO mode, as after that,
2036                  * by the time we unmount, it might have left a transaction open,
2037                  * so we would leak the transaction and/or crash.
2038                  */
2039                 btrfs_qgroup_wait_for_completion(fs_info, false);
2040
2041                 ret = btrfs_commit_super(fs_info);
2042                 if (ret)
2043                         goto restore;
2044         } else {
2045                 if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
2046                         btrfs_err(fs_info,
2047                                 "Remounting read-write after error is not allowed");
2048                         ret = -EINVAL;
2049                         goto restore;
2050                 }
2051                 if (btrfs_super_compat_ro_flags(fs_info->super_copy) &
2052                     ~BTRFS_FEATURE_COMPAT_RO_SUPP) {
2053                         btrfs_err(fs_info,
2054                 "can not remount read-write due to unsupported optional flags 0x%llx",
2055                                 btrfs_super_compat_ro_flags(fs_info->super_copy) &
2056                                 ~BTRFS_FEATURE_COMPAT_RO_SUPP);
2057                         ret = -EINVAL;
2058                         goto restore;
2059                 }
2060                 if (fs_info->fs_devices->rw_devices == 0) {
2061                         ret = -EACCES;
2062                         goto restore;
2063                 }
2064
2065                 if (!btrfs_check_rw_degradable(fs_info, NULL)) {
2066                         btrfs_warn(fs_info,
2067                 "too many missing devices, writable remount is not allowed");
2068                         ret = -EACCES;
2069                         goto restore;
2070                 }
2071
2072                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
2073                         btrfs_warn(fs_info,
2074                 "mount required to replay tree-log, cannot remount read-write");
2075                         ret = -EINVAL;
2076                         goto restore;
2077                 }
2078
2079                 /*
2080                  * NOTE: when remounting with a change that does writes, don't
2081                  * put it anywhere above this point, as we are not sure to be
2082                  * safe to write until we pass the above checks.
2083                  */
2084                 ret = btrfs_start_pre_rw_mount(fs_info);
2085                 if (ret)
2086                         goto restore;
2087
2088                 btrfs_clear_sb_rdonly(sb);
2089
2090                 set_bit(BTRFS_FS_OPEN, &fs_info->flags);
2091         }
2092 out:
2093         /*
2094          * We need to set SB_I_VERSION here otherwise it'll get cleared by VFS,
2095          * since the absence of the flag means it can be toggled off by remount.
2096          */
2097         *flags |= SB_I_VERSION;
2098
2099         wake_up_process(fs_info->transaction_kthread);
2100         btrfs_remount_cleanup(fs_info, old_opts);
2101         btrfs_clear_oneshot_options(fs_info);
2102         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
2103
2104         return 0;
2105
2106 restore:
2107         /* We've hit an error - don't reset SB_RDONLY */
2108         if (sb_rdonly(sb))
2109                 old_flags |= SB_RDONLY;
2110         if (!(old_flags & SB_RDONLY))
2111                 clear_bit(BTRFS_FS_STATE_RO, &fs_info->fs_state);
2112         sb->s_flags = old_flags;
2113         fs_info->mount_opt = old_opts;
2114         fs_info->compress_type = old_compress_type;
2115         fs_info->max_inline = old_max_inline;
2116         btrfs_resize_thread_pool(fs_info,
2117                 old_thread_pool_size, fs_info->thread_pool_size);
2118         fs_info->metadata_ratio = old_metadata_ratio;
2119         btrfs_remount_cleanup(fs_info, old_opts);
2120         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
2121
2122         return ret;
2123 }
2124
2125 /* Used to sort the devices by max_avail(descending sort) */
2126 static int btrfs_cmp_device_free_bytes(const void *a, const void *b)
2127 {
2128         const struct btrfs_device_info *dev_info1 = a;
2129         const struct btrfs_device_info *dev_info2 = b;
2130
2131         if (dev_info1->max_avail > dev_info2->max_avail)
2132                 return -1;
2133         else if (dev_info1->max_avail < dev_info2->max_avail)
2134                 return 1;
2135         return 0;
2136 }
2137
2138 /*
2139  * sort the devices by max_avail, in which max free extent size of each device
2140  * is stored.(Descending Sort)
2141  */
2142 static inline void btrfs_descending_sort_devices(
2143                                         struct btrfs_device_info *devices,
2144                                         size_t nr_devices)
2145 {
2146         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
2147              btrfs_cmp_device_free_bytes, NULL);
2148 }
2149
2150 /*
2151  * The helper to calc the free space on the devices that can be used to store
2152  * file data.
2153  */
2154 static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
2155                                               u64 *free_bytes)
2156 {
2157         struct btrfs_device_info *devices_info;
2158         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
2159         struct btrfs_device *device;
2160         u64 type;
2161         u64 avail_space;
2162         u64 min_stripe_size;
2163         int num_stripes = 1;
2164         int i = 0, nr_devices;
2165         const struct btrfs_raid_attr *rattr;
2166
2167         /*
2168          * We aren't under the device list lock, so this is racy-ish, but good
2169          * enough for our purposes.
2170          */
2171         nr_devices = fs_info->fs_devices->open_devices;
2172         if (!nr_devices) {
2173                 smp_mb();
2174                 nr_devices = fs_info->fs_devices->open_devices;
2175                 ASSERT(nr_devices);
2176                 if (!nr_devices) {
2177                         *free_bytes = 0;
2178                         return 0;
2179                 }
2180         }
2181
2182         devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
2183                                GFP_KERNEL);
2184         if (!devices_info)
2185                 return -ENOMEM;
2186
2187         /* calc min stripe number for data space allocation */
2188         type = btrfs_data_alloc_profile(fs_info);
2189         rattr = &btrfs_raid_array[btrfs_bg_flags_to_raid_index(type)];
2190
2191         if (type & BTRFS_BLOCK_GROUP_RAID0)
2192                 num_stripes = nr_devices;
2193         else if (type & BTRFS_BLOCK_GROUP_RAID1)
2194                 num_stripes = 2;
2195         else if (type & BTRFS_BLOCK_GROUP_RAID1C3)
2196                 num_stripes = 3;
2197         else if (type & BTRFS_BLOCK_GROUP_RAID1C4)
2198                 num_stripes = 4;
2199         else if (type & BTRFS_BLOCK_GROUP_RAID10)
2200                 num_stripes = 4;
2201
2202         /* Adjust for more than 1 stripe per device */
2203         min_stripe_size = rattr->dev_stripes * BTRFS_STRIPE_LEN;
2204
2205         rcu_read_lock();
2206         list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
2207                 if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
2208                                                 &device->dev_state) ||
2209                     !device->bdev ||
2210                     test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
2211                         continue;
2212
2213                 if (i >= nr_devices)
2214                         break;
2215
2216                 avail_space = device->total_bytes - device->bytes_used;
2217
2218                 /* align with stripe_len */
2219                 avail_space = rounddown(avail_space, BTRFS_STRIPE_LEN);
2220
2221                 /*
2222                  * In order to avoid overwriting the superblock on the drive,
2223                  * btrfs starts at an offset of at least 1MB when doing chunk
2224                  * allocation.
2225                  *
2226                  * This ensures we have at least min_stripe_size free space
2227                  * after excluding 1MB.
2228                  */
2229                 if (avail_space <= SZ_1M + min_stripe_size)
2230                         continue;
2231
2232                 avail_space -= SZ_1M;
2233
2234                 devices_info[i].dev = device;
2235                 devices_info[i].max_avail = avail_space;
2236
2237                 i++;
2238         }
2239         rcu_read_unlock();
2240
2241         nr_devices = i;
2242
2243         btrfs_descending_sort_devices(devices_info, nr_devices);
2244
2245         i = nr_devices - 1;
2246         avail_space = 0;
2247         while (nr_devices >= rattr->devs_min) {
2248                 num_stripes = min(num_stripes, nr_devices);
2249
2250                 if (devices_info[i].max_avail >= min_stripe_size) {
2251                         int j;
2252                         u64 alloc_size;
2253
2254                         avail_space += devices_info[i].max_avail * num_stripes;
2255                         alloc_size = devices_info[i].max_avail;
2256                         for (j = i + 1 - num_stripes; j <= i; j++)
2257                                 devices_info[j].max_avail -= alloc_size;
2258                 }
2259                 i--;
2260                 nr_devices--;
2261         }
2262
2263         kfree(devices_info);
2264         *free_bytes = avail_space;
2265         return 0;
2266 }
2267
2268 /*
2269  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
2270  *
2271  * If there's a redundant raid level at DATA block groups, use the respective
2272  * multiplier to scale the sizes.
2273  *
2274  * Unused device space usage is based on simulating the chunk allocator
2275  * algorithm that respects the device sizes and order of allocations.  This is
2276  * a close approximation of the actual use but there are other factors that may
2277  * change the result (like a new metadata chunk).
2278  *
2279  * If metadata is exhausted, f_bavail will be 0.
2280  */
2281 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
2282 {
2283         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
2284         struct btrfs_super_block *disk_super = fs_info->super_copy;
2285         struct btrfs_space_info *found;
2286         u64 total_used = 0;
2287         u64 total_free_data = 0;
2288         u64 total_free_meta = 0;
2289         u32 bits = fs_info->sectorsize_bits;
2290         __be32 *fsid = (__be32 *)fs_info->fs_devices->fsid;
2291         unsigned factor = 1;
2292         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
2293         int ret;
2294         u64 thresh = 0;
2295         int mixed = 0;
2296
2297         list_for_each_entry(found, &fs_info->space_info, list) {
2298                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
2299                         int i;
2300
2301                         total_free_data += found->disk_total - found->disk_used;
2302                         total_free_data -=
2303                                 btrfs_account_ro_block_groups_free_space(found);
2304
2305                         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
2306                                 if (!list_empty(&found->block_groups[i]))
2307                                         factor = btrfs_bg_type_to_factor(
2308                                                 btrfs_raid_array[i].bg_flag);
2309                         }
2310                 }
2311
2312                 /*
2313                  * Metadata in mixed block goup profiles are accounted in data
2314                  */
2315                 if (!mixed && found->flags & BTRFS_BLOCK_GROUP_METADATA) {
2316                         if (found->flags & BTRFS_BLOCK_GROUP_DATA)
2317                                 mixed = 1;
2318                         else
2319                                 total_free_meta += found->disk_total -
2320                                         found->disk_used;
2321                 }
2322
2323                 total_used += found->disk_used;
2324         }
2325
2326         buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
2327         buf->f_blocks >>= bits;
2328         buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
2329
2330         /* Account global block reserve as used, it's in logical size already */
2331         spin_lock(&block_rsv->lock);
2332         /* Mixed block groups accounting is not byte-accurate, avoid overflow */
2333         if (buf->f_bfree >= block_rsv->size >> bits)
2334                 buf->f_bfree -= block_rsv->size >> bits;
2335         else
2336                 buf->f_bfree = 0;
2337         spin_unlock(&block_rsv->lock);
2338
2339         buf->f_bavail = div_u64(total_free_data, factor);
2340         ret = btrfs_calc_avail_data_space(fs_info, &total_free_data);
2341         if (ret)
2342                 return ret;
2343         buf->f_bavail += div_u64(total_free_data, factor);
2344         buf->f_bavail = buf->f_bavail >> bits;
2345
2346         /*
2347          * We calculate the remaining metadata space minus global reserve. If
2348          * this is (supposedly) smaller than zero, there's no space. But this
2349          * does not hold in practice, the exhausted state happens where's still
2350          * some positive delta. So we apply some guesswork and compare the
2351          * delta to a 4M threshold.  (Practically observed delta was ~2M.)
2352          *
2353          * We probably cannot calculate the exact threshold value because this
2354          * depends on the internal reservations requested by various
2355          * operations, so some operations that consume a few metadata will
2356          * succeed even if the Avail is zero. But this is better than the other
2357          * way around.
2358          */
2359         thresh = SZ_4M;
2360
2361         /*
2362          * We only want to claim there's no available space if we can no longer
2363          * allocate chunks for our metadata profile and our global reserve will
2364          * not fit in the free metadata space.  If we aren't ->full then we
2365          * still can allocate chunks and thus are fine using the currently
2366          * calculated f_bavail.
2367          */
2368         if (!mixed && block_rsv->space_info->full &&
2369             total_free_meta - thresh < block_rsv->size)
2370                 buf->f_bavail = 0;
2371
2372         buf->f_type = BTRFS_SUPER_MAGIC;
2373         buf->f_bsize = dentry->d_sb->s_blocksize;
2374         buf->f_namelen = BTRFS_NAME_LEN;
2375
2376         /* We treat it as constant endianness (it doesn't matter _which_)
2377            because we want the fsid to come out the same whether mounted
2378            on a big-endian or little-endian host */
2379         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
2380         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
2381         /* Mask in the root object ID too, to disambiguate subvols */
2382         buf->f_fsid.val[0] ^=
2383                 BTRFS_I(d_inode(dentry))->root->root_key.objectid >> 32;
2384         buf->f_fsid.val[1] ^=
2385                 BTRFS_I(d_inode(dentry))->root->root_key.objectid;
2386
2387         return 0;
2388 }
2389
2390 static void btrfs_kill_super(struct super_block *sb)
2391 {
2392         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2393         kill_anon_super(sb);
2394         btrfs_free_fs_info(fs_info);
2395 }
2396
2397 static struct file_system_type btrfs_fs_type = {
2398         .owner          = THIS_MODULE,
2399         .name           = "btrfs",
2400         .mount          = btrfs_mount,
2401         .kill_sb        = btrfs_kill_super,
2402         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2403 };
2404
2405 static struct file_system_type btrfs_root_fs_type = {
2406         .owner          = THIS_MODULE,
2407         .name           = "btrfs",
2408         .mount          = btrfs_mount_root,
2409         .kill_sb        = btrfs_kill_super,
2410         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA | FS_ALLOW_IDMAP,
2411 };
2412
2413 MODULE_ALIAS_FS("btrfs");
2414
2415 static int btrfs_control_open(struct inode *inode, struct file *file)
2416 {
2417         /*
2418          * The control file's private_data is used to hold the
2419          * transaction when it is started and is used to keep
2420          * track of whether a transaction is already in progress.
2421          */
2422         file->private_data = NULL;
2423         return 0;
2424 }
2425
2426 /*
2427  * Used by /dev/btrfs-control for devices ioctls.
2428  */
2429 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
2430                                 unsigned long arg)
2431 {
2432         struct btrfs_ioctl_vol_args *vol;
2433         struct btrfs_device *device = NULL;
2434         int ret = -ENOTTY;
2435
2436         if (!capable(CAP_SYS_ADMIN))
2437                 return -EPERM;
2438
2439         vol = memdup_user((void __user *)arg, sizeof(*vol));
2440         if (IS_ERR(vol))
2441                 return PTR_ERR(vol);
2442         vol->name[BTRFS_PATH_NAME_MAX] = '\0';
2443
2444         switch (cmd) {
2445         case BTRFS_IOC_SCAN_DEV:
2446                 mutex_lock(&uuid_mutex);
2447                 device = btrfs_scan_one_device(vol->name, FMODE_READ,
2448                                                &btrfs_root_fs_type);
2449                 ret = PTR_ERR_OR_ZERO(device);
2450                 mutex_unlock(&uuid_mutex);
2451                 break;
2452         case BTRFS_IOC_FORGET_DEV:
2453                 ret = btrfs_forget_devices(vol->name);
2454                 break;
2455         case BTRFS_IOC_DEVICES_READY:
2456                 mutex_lock(&uuid_mutex);
2457                 device = btrfs_scan_one_device(vol->name, FMODE_READ,
2458                                                &btrfs_root_fs_type);
2459                 if (IS_ERR(device)) {
2460                         mutex_unlock(&uuid_mutex);
2461                         ret = PTR_ERR(device);
2462                         break;
2463                 }
2464                 ret = !(device->fs_devices->num_devices ==
2465                         device->fs_devices->total_devices);
2466                 mutex_unlock(&uuid_mutex);
2467                 break;
2468         case BTRFS_IOC_GET_SUPPORTED_FEATURES:
2469                 ret = btrfs_ioctl_get_supported_features((void __user*)arg);
2470                 break;
2471         }
2472
2473         kfree(vol);
2474         return ret;
2475 }
2476
2477 static int btrfs_freeze(struct super_block *sb)
2478 {
2479         struct btrfs_trans_handle *trans;
2480         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2481         struct btrfs_root *root = fs_info->tree_root;
2482
2483         set_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2484         /*
2485          * We don't need a barrier here, we'll wait for any transaction that
2486          * could be in progress on other threads (and do delayed iputs that
2487          * we want to avoid on a frozen filesystem), or do the commit
2488          * ourselves.
2489          */
2490         trans = btrfs_attach_transaction_barrier(root);
2491         if (IS_ERR(trans)) {
2492                 /* no transaction, don't bother */
2493                 if (PTR_ERR(trans) == -ENOENT)
2494                         return 0;
2495                 return PTR_ERR(trans);
2496         }
2497         return btrfs_commit_transaction(trans);
2498 }
2499
2500 static int check_dev_super(struct btrfs_device *dev)
2501 {
2502         struct btrfs_fs_info *fs_info = dev->fs_info;
2503         struct btrfs_super_block *sb;
2504         u16 csum_type;
2505         int ret = 0;
2506
2507         /* This should be called with fs still frozen. */
2508         ASSERT(test_bit(BTRFS_FS_FROZEN, &fs_info->flags));
2509
2510         /* Missing dev, no need to check. */
2511         if (!dev->bdev)
2512                 return 0;
2513
2514         /* Only need to check the primary super block. */
2515         sb = btrfs_read_dev_one_super(dev->bdev, 0, true);
2516         if (IS_ERR(sb))
2517                 return PTR_ERR(sb);
2518
2519         /* Verify the checksum. */
2520         csum_type = btrfs_super_csum_type(sb);
2521         if (csum_type != btrfs_super_csum_type(fs_info->super_copy)) {
2522                 btrfs_err(fs_info, "csum type changed, has %u expect %u",
2523                           csum_type, btrfs_super_csum_type(fs_info->super_copy));
2524                 ret = -EUCLEAN;
2525                 goto out;
2526         }
2527
2528         if (btrfs_check_super_csum(fs_info, sb)) {
2529                 btrfs_err(fs_info, "csum for on-disk super block no longer matches");
2530                 ret = -EUCLEAN;
2531                 goto out;
2532         }
2533
2534         /* Btrfs_validate_super() includes fsid check against super->fsid. */
2535         ret = btrfs_validate_super(fs_info, sb, 0);
2536         if (ret < 0)
2537                 goto out;
2538
2539         if (btrfs_super_generation(sb) != fs_info->last_trans_committed) {
2540                 btrfs_err(fs_info, "transid mismatch, has %llu expect %llu",
2541                         btrfs_super_generation(sb),
2542                         fs_info->last_trans_committed);
2543                 ret = -EUCLEAN;
2544                 goto out;
2545         }
2546 out:
2547         btrfs_release_disk_super(sb);
2548         return ret;
2549 }
2550
2551 static int btrfs_unfreeze(struct super_block *sb)
2552 {
2553         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2554         struct btrfs_device *device;
2555         int ret = 0;
2556
2557         /*
2558          * Make sure the fs is not changed by accident (like hibernation then
2559          * modified by other OS).
2560          * If we found anything wrong, we mark the fs error immediately.
2561          *
2562          * And since the fs is frozen, no one can modify the fs yet, thus
2563          * we don't need to hold device_list_mutex.
2564          */
2565         list_for_each_entry(device, &fs_info->fs_devices->devices, dev_list) {
2566                 ret = check_dev_super(device);
2567                 if (ret < 0) {
2568                         btrfs_handle_fs_error(fs_info, ret,
2569                                 "super block on devid %llu got modified unexpectedly",
2570                                 device->devid);
2571                         break;
2572                 }
2573         }
2574         clear_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2575
2576         /*
2577          * We still return 0, to allow VFS layer to unfreeze the fs even the
2578          * above checks failed. Since the fs is either fine or read-only, we're
2579          * safe to continue, without causing further damage.
2580          */
2581         return 0;
2582 }
2583
2584 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
2585 {
2586         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
2587
2588         /*
2589          * There should be always a valid pointer in latest_dev, it may be stale
2590          * for a short moment in case it's being deleted but still valid until
2591          * the end of RCU grace period.
2592          */
2593         rcu_read_lock();
2594         seq_escape(m, rcu_str_deref(fs_info->fs_devices->latest_dev->name), " \t\n\\");
2595         rcu_read_unlock();
2596
2597         return 0;
2598 }
2599
2600 static const struct super_operations btrfs_super_ops = {
2601         .drop_inode     = btrfs_drop_inode,
2602         .evict_inode    = btrfs_evict_inode,
2603         .put_super      = btrfs_put_super,
2604         .sync_fs        = btrfs_sync_fs,
2605         .show_options   = btrfs_show_options,
2606         .show_devname   = btrfs_show_devname,
2607         .alloc_inode    = btrfs_alloc_inode,
2608         .destroy_inode  = btrfs_destroy_inode,
2609         .free_inode     = btrfs_free_inode,
2610         .statfs         = btrfs_statfs,
2611         .remount_fs     = btrfs_remount,
2612         .freeze_fs      = btrfs_freeze,
2613         .unfreeze_fs    = btrfs_unfreeze,
2614 };
2615
2616 static const struct file_operations btrfs_ctl_fops = {
2617         .open = btrfs_control_open,
2618         .unlocked_ioctl  = btrfs_control_ioctl,
2619         .compat_ioctl = compat_ptr_ioctl,
2620         .owner   = THIS_MODULE,
2621         .llseek = noop_llseek,
2622 };
2623
2624 static struct miscdevice btrfs_misc = {
2625         .minor          = BTRFS_MINOR,
2626         .name           = "btrfs-control",
2627         .fops           = &btrfs_ctl_fops
2628 };
2629
2630 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2631 MODULE_ALIAS("devname:btrfs-control");
2632
2633 static int __init btrfs_interface_init(void)
2634 {
2635         return misc_register(&btrfs_misc);
2636 }
2637
2638 static __cold void btrfs_interface_exit(void)
2639 {
2640         misc_deregister(&btrfs_misc);
2641 }
2642
2643 static void __init btrfs_print_mod_info(void)
2644 {
2645         static const char options[] = ""
2646 #ifdef CONFIG_BTRFS_DEBUG
2647                         ", debug=on"
2648 #endif
2649 #ifdef CONFIG_BTRFS_ASSERT
2650                         ", assert=on"
2651 #endif
2652 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2653                         ", integrity-checker=on"
2654 #endif
2655 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
2656                         ", ref-verify=on"
2657 #endif
2658 #ifdef CONFIG_BLK_DEV_ZONED
2659                         ", zoned=yes"
2660 #else
2661                         ", zoned=no"
2662 #endif
2663 #ifdef CONFIG_FS_VERITY
2664                         ", fsverity=yes"
2665 #else
2666                         ", fsverity=no"
2667 #endif
2668                         ;
2669         pr_info("Btrfs loaded, crc32c=%s%s\n", crc32c_impl(), options);
2670 }
2671
2672 static int __init init_btrfs_fs(void)
2673 {
2674         int err;
2675
2676         btrfs_props_init();
2677
2678         err = btrfs_init_sysfs();
2679         if (err)
2680                 return err;
2681
2682         btrfs_init_compress();
2683
2684         err = btrfs_init_cachep();
2685         if (err)
2686                 goto free_compress;
2687
2688         err = extent_io_init();
2689         if (err)
2690                 goto free_cachep;
2691
2692         err = extent_state_cache_init();
2693         if (err)
2694                 goto free_extent_io;
2695
2696         err = extent_map_init();
2697         if (err)
2698                 goto free_extent_state_cache;
2699
2700         err = ordered_data_init();
2701         if (err)
2702                 goto free_extent_map;
2703
2704         err = btrfs_delayed_inode_init();
2705         if (err)
2706                 goto free_ordered_data;
2707
2708         err = btrfs_auto_defrag_init();
2709         if (err)
2710                 goto free_delayed_inode;
2711
2712         err = btrfs_delayed_ref_init();
2713         if (err)
2714                 goto free_auto_defrag;
2715
2716         err = btrfs_prelim_ref_init();
2717         if (err)
2718                 goto free_delayed_ref;
2719
2720         err = btrfs_end_io_wq_init();
2721         if (err)
2722                 goto free_prelim_ref;
2723
2724         err = btrfs_interface_init();
2725         if (err)
2726                 goto free_end_io_wq;
2727
2728         btrfs_print_mod_info();
2729
2730         err = btrfs_run_sanity_tests();
2731         if (err)
2732                 goto unregister_ioctl;
2733
2734         err = register_filesystem(&btrfs_fs_type);
2735         if (err)
2736                 goto unregister_ioctl;
2737
2738         return 0;
2739
2740 unregister_ioctl:
2741         btrfs_interface_exit();
2742 free_end_io_wq:
2743         btrfs_end_io_wq_exit();
2744 free_prelim_ref:
2745         btrfs_prelim_ref_exit();
2746 free_delayed_ref:
2747         btrfs_delayed_ref_exit();
2748 free_auto_defrag:
2749         btrfs_auto_defrag_exit();
2750 free_delayed_inode:
2751         btrfs_delayed_inode_exit();
2752 free_ordered_data:
2753         ordered_data_exit();
2754 free_extent_map:
2755         extent_map_exit();
2756 free_extent_state_cache:
2757         extent_state_cache_exit();
2758 free_extent_io:
2759         extent_io_exit();
2760 free_cachep:
2761         btrfs_destroy_cachep();
2762 free_compress:
2763         btrfs_exit_compress();
2764         btrfs_exit_sysfs();
2765
2766         return err;
2767 }
2768
2769 static void __exit exit_btrfs_fs(void)
2770 {
2771         btrfs_destroy_cachep();
2772         btrfs_delayed_ref_exit();
2773         btrfs_auto_defrag_exit();
2774         btrfs_delayed_inode_exit();
2775         btrfs_prelim_ref_exit();
2776         ordered_data_exit();
2777         extent_map_exit();
2778         extent_state_cache_exit();
2779         extent_io_exit();
2780         btrfs_interface_exit();
2781         btrfs_end_io_wq_exit();
2782         unregister_filesystem(&btrfs_fs_type);
2783         btrfs_exit_sysfs();
2784         btrfs_cleanup_fs_uuids();
2785         btrfs_exit_compress();
2786 }
2787
2788 late_initcall(init_btrfs_fs);
2789 module_exit(exit_btrfs_fs)
2790
2791 MODULE_LICENSE("GPL");
2792 MODULE_SOFTDEP("pre: crc32c");
2793 MODULE_SOFTDEP("pre: xxhash64");
2794 MODULE_SOFTDEP("pre: sha256");
2795 MODULE_SOFTDEP("pre: blake2b-256");