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