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