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/ratelimit.h>
  27 #include <linux/crc32c.h>
  28 #include <linux/btrfs.h>
  29 #include <linux/security.h>
  30 #include <linux/fs_parser.h>
  31 #include <linux/swap.h>
  32 #include "messages.h"
  33 #include "delayed-inode.h"
  34 #include "ctree.h"
  35 #include "disk-io.h"
  36 #include "transaction.h"
  37 #include "btrfs_inode.h"
  38 #include "direct-io.h"
  39 #include "props.h"
  40 #include "xattr.h"
  41 #include "bio.h"
  42 #include "export.h"
  43 #include "compression.h"
  44 #include "dev-replace.h"
  45 #include "free-space-cache.h"
  46 #include "backref.h"
  47 #include "space-info.h"
  48 #include "sysfs.h"
  49 #include "zoned.h"
  50 #include "tests/btrfs-tests.h"
  51 #include "block-group.h"
  52 #include "discard.h"
  53 #include "qgroup.h"
  54 #include "raid56.h"
  55 #include "fs.h"
  56 #include "accessors.h"
  57 #include "defrag.h"
  58 #include "dir-item.h"
  59 #include "ioctl.h"
  60 #include "scrub.h"
  61 #include "verity.h"
  62 #include "super.h"
  63 #include "extent-tree.h"
  64 #define CREATE_TRACE_POINTS
  65 #include <trace/events/btrfs.h>
  66
  67 static const struct super_operations btrfs_super_ops;
  68 static struct file_system_type btrfs_fs_type;
  69
  70 static void btrfs_put_super(struct super_block *sb)
  71 {
  72         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
  73
  74         btrfs_info(fs_info, "last unmount of filesystem %pU", fs_info->fs_devices->fsid);
  75         close_ctree(fs_info);
  76 }
  77
  78 /* Store the mount options related information. */
  79 struct btrfs_fs_context {
  80         char *subvol_name;
  81         u64 subvol_objectid;
  82         u64 max_inline;
  83         u32 commit_interval;
  84         u32 metadata_ratio;
  85         u32 thread_pool_size;
  86         unsigned long long mount_opt;
  87         unsigned long compress_type:4;
  88         unsigned int compress_level;
  89         refcount_t refs;
  90 };
  91
  92 enum {
  93         Opt_acl,
  94         Opt_clear_cache,
  95         Opt_commit_interval,
  96         Opt_compress,
  97         Opt_compress_force,
  98         Opt_compress_force_type,
  99         Opt_compress_type,
 100         Opt_degraded,
 101         Opt_device,
 102         Opt_fatal_errors,
 103         Opt_flushoncommit,
 104         Opt_max_inline,
 105         Opt_barrier,
 106         Opt_datacow,
 107         Opt_datasum,
 108         Opt_defrag,
 109         Opt_discard,
 110         Opt_discard_mode,
 111         Opt_ratio,
 112         Opt_rescan_uuid_tree,
 113         Opt_skip_balance,
 114         Opt_space_cache,
 115         Opt_space_cache_version,
 116         Opt_ssd,
 117         Opt_ssd_spread,
 118         Opt_subvol,
 119         Opt_subvol_empty,
 120         Opt_subvolid,
 121         Opt_thread_pool,
 122         Opt_treelog,
 123         Opt_user_subvol_rm_allowed,
 124         Opt_norecovery,
 125
 126         /* Rescue options */
 127         Opt_rescue,
 128         Opt_usebackuproot,
 129         Opt_nologreplay,
 130
 131         /* Debugging options */
 132         Opt_enospc_debug,
 133 #ifdef CONFIG_BTRFS_DEBUG
 134         Opt_fragment, Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 135 #endif
 136 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 137         Opt_ref_verify,
 138 #endif
 139         Opt_err,
 140 };
 141
 142 enum {
 143         Opt_fatal_errors_panic,
 144         Opt_fatal_errors_bug,
 145 };
 146
 147 static const struct constant_table btrfs_parameter_fatal_errors[] = {
 148         { "panic", Opt_fatal_errors_panic },
 149         { "bug", Opt_fatal_errors_bug },
 150         {}
 151 };
 152
 153 enum {
 154         Opt_discard_sync,
 155         Opt_discard_async,
 156 };
 157
 158 static const struct constant_table btrfs_parameter_discard[] = {
 159         { "sync", Opt_discard_sync },
 160         { "async", Opt_discard_async },
 161         {}
 162 };
 163
 164 enum {
 165         Opt_space_cache_v1,
 166         Opt_space_cache_v2,
 167 };
 168
 169 static const struct constant_table btrfs_parameter_space_cache[] = {
 170         { "v1", Opt_space_cache_v1 },
 171         { "v2", Opt_space_cache_v2 },
 172         {}
 173 };
 174
 175 enum {
 176         Opt_rescue_usebackuproot,
 177         Opt_rescue_nologreplay,
 178         Opt_rescue_ignorebadroots,
 179         Opt_rescue_ignoredatacsums,
 180         Opt_rescue_ignoremetacsums,
 181         Opt_rescue_ignoresuperflags,
 182         Opt_rescue_parameter_all,
 183 };
 184
 185 static const struct constant_table btrfs_parameter_rescue[] = {
 186         { "usebackuproot", Opt_rescue_usebackuproot },
 187         { "nologreplay", Opt_rescue_nologreplay },
 188         { "ignorebadroots", Opt_rescue_ignorebadroots },
 189         { "ibadroots", Opt_rescue_ignorebadroots },
 190         { "ignoredatacsums", Opt_rescue_ignoredatacsums },
 191         { "ignoremetacsums", Opt_rescue_ignoremetacsums},
 192         { "ignoresuperflags", Opt_rescue_ignoresuperflags},
 193         { "idatacsums", Opt_rescue_ignoredatacsums },
 194         { "imetacsums", Opt_rescue_ignoremetacsums},
 195         { "isuperflags", Opt_rescue_ignoresuperflags},
 196         { "all", Opt_rescue_parameter_all },
 197         {}
 198 };
 199
 200 #ifdef CONFIG_BTRFS_DEBUG
 201 enum {
 202         Opt_fragment_parameter_data,
 203         Opt_fragment_parameter_metadata,
 204         Opt_fragment_parameter_all,
 205 };
 206
 207 static const struct constant_table btrfs_parameter_fragment[] = {
 208         { "data", Opt_fragment_parameter_data },
 209         { "metadata", Opt_fragment_parameter_metadata },
 210         { "all", Opt_fragment_parameter_all },
 211         {}
 212 };
 213 #endif
 214
 215 static const struct fs_parameter_spec btrfs_fs_parameters[] = {
 216         fsparam_flag_no("acl", Opt_acl),
 217         fsparam_flag_no("autodefrag", Opt_defrag),
 218         fsparam_flag_no("barrier", Opt_barrier),
 219         fsparam_flag("clear_cache", Opt_clear_cache),
 220         fsparam_u32("commit", Opt_commit_interval),
 221         fsparam_flag("compress", Opt_compress),
 222         fsparam_string("compress", Opt_compress_type),
 223         fsparam_flag("compress-force", Opt_compress_force),
 224         fsparam_string("compress-force", Opt_compress_force_type),
 225         fsparam_flag_no("datacow", Opt_datacow),
 226         fsparam_flag_no("datasum", Opt_datasum),
 227         fsparam_flag("degraded", Opt_degraded),
 228         fsparam_string("device", Opt_device),
 229         fsparam_flag_no("discard", Opt_discard),
 230         fsparam_enum("discard", Opt_discard_mode, btrfs_parameter_discard),
 231         fsparam_enum("fatal_errors", Opt_fatal_errors, btrfs_parameter_fatal_errors),
 232         fsparam_flag_no("flushoncommit", Opt_flushoncommit),
 233         fsparam_string("max_inline", Opt_max_inline),
 234         fsparam_u32("metadata_ratio", Opt_ratio),
 235         fsparam_flag("rescan_uuid_tree", Opt_rescan_uuid_tree),
 236         fsparam_flag("skip_balance", Opt_skip_balance),
 237         fsparam_flag_no("space_cache", Opt_space_cache),
 238         fsparam_enum("space_cache", Opt_space_cache_version, btrfs_parameter_space_cache),
 239         fsparam_flag_no("ssd", Opt_ssd),
 240         fsparam_flag_no("ssd_spread", Opt_ssd_spread),
 241         fsparam_string("subvol", Opt_subvol),
 242         fsparam_flag("subvol=", Opt_subvol_empty),
 243         fsparam_u64("subvolid", Opt_subvolid),
 244         fsparam_u32("thread_pool", Opt_thread_pool),
 245         fsparam_flag_no("treelog", Opt_treelog),
 246         fsparam_flag("user_subvol_rm_allowed", Opt_user_subvol_rm_allowed),
 247
 248         /* Rescue options. */
 249         fsparam_enum("rescue", Opt_rescue, btrfs_parameter_rescue),
 250         /* Deprecated, with alias rescue=nologreplay */
 251         __fsparam(NULL, "nologreplay", Opt_nologreplay, fs_param_deprecated, NULL),
 252         /* Deprecated, with alias rescue=usebackuproot */
 253         __fsparam(NULL, "usebackuproot", Opt_usebackuproot, fs_param_deprecated, NULL),
 254         /* For compatibility only, alias for "rescue=nologreplay". */
 255         fsparam_flag("norecovery", Opt_norecovery),
 256
 257         /* Debugging options. */
 258         fsparam_flag_no("enospc_debug", Opt_enospc_debug),
 259 #ifdef CONFIG_BTRFS_DEBUG
 260         fsparam_enum("fragment", Opt_fragment, btrfs_parameter_fragment),
 261 #endif
 262 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 263         fsparam_flag("ref_verify", Opt_ref_verify),
 264 #endif
 265         {}
 266 };
 267
 268 /* No support for restricting writes to btrfs devices yet... */
 269 static inline blk_mode_t btrfs_open_mode(struct fs_context *fc)
 270 {
 271         return sb_open_mode(fc->sb_flags) & ~BLK_OPEN_RESTRICT_WRITES;
 272 }
 273
 274 static int btrfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 275 {
 276         struct btrfs_fs_context *ctx = fc->fs_private;
 277         struct fs_parse_result result;
 278         int opt;
 279
 280         opt = fs_parse(fc, btrfs_fs_parameters, param, &result);
 281         if (opt < 0)
 282                 return opt;
 283
 284         switch (opt) {
 285         case Opt_degraded:
 286                 btrfs_set_opt(ctx->mount_opt, DEGRADED);
 287                 break;
 288         case Opt_subvol_empty:
 289                 /*
 290                  * This exists because we used to allow it on accident, so we're
 291                  * keeping it to maintain ABI.  See 37becec95ac3 ("Btrfs: allow
 292                  * empty subvol= again").
 293                  */
 294                 break;
 295         case Opt_subvol:
 296                 kfree(ctx->subvol_name);
 297                 ctx->subvol_name = kstrdup(param->string, GFP_KERNEL);
 298                 if (!ctx->subvol_name)
 299                         return -ENOMEM;
 300                 break;
 301         case Opt_subvolid:
 302                 ctx->subvol_objectid = result.uint_64;
 303
 304                 /* subvolid=0 means give me the original fs_tree. */
 305                 if (!ctx->subvol_objectid)
 306                         ctx->subvol_objectid = BTRFS_FS_TREE_OBJECTID;
 307                 break;
 308         case Opt_device: {
 309                 struct btrfs_device *device;
 310                 blk_mode_t mode = btrfs_open_mode(fc);
 311
 312                 mutex_lock(&uuid_mutex);
 313                 device = btrfs_scan_one_device(param->string, mode, false);
 314                 mutex_unlock(&uuid_mutex);
 315                 if (IS_ERR(device))
 316                         return PTR_ERR(device);
 317                 break;
 318         }
 319         case Opt_datasum:
 320                 if (result.negated) {
 321                         btrfs_set_opt(ctx->mount_opt, NODATASUM);
 322                 } else {
 323                         btrfs_clear_opt(ctx->mount_opt, NODATACOW);
 324                         btrfs_clear_opt(ctx->mount_opt, NODATASUM);
 325                 }
 326                 break;
 327         case Opt_datacow:
 328                 if (result.negated) {
 329                         btrfs_clear_opt(ctx->mount_opt, COMPRESS);
 330                         btrfs_clear_opt(ctx->mount_opt, FORCE_COMPRESS);
 331                         btrfs_set_opt(ctx->mount_opt, NODATACOW);
 332                         btrfs_set_opt(ctx->mount_opt, NODATASUM);
 333                 } else {
 334                         btrfs_clear_opt(ctx->mount_opt, NODATACOW);
 335                 }
 336                 break;
 337         case Opt_compress_force:
 338         case Opt_compress_force_type:
 339                 btrfs_set_opt(ctx->mount_opt, FORCE_COMPRESS);
 340                 fallthrough;
 341         case Opt_compress:
 342         case Opt_compress_type:
 343                 if (opt == Opt_compress || opt == Opt_compress_force) {
 344                         ctx->compress_type = BTRFS_COMPRESS_ZLIB;
 345                         ctx->compress_level = BTRFS_ZLIB_DEFAULT_LEVEL;
 346                         btrfs_set_opt(ctx->mount_opt, COMPRESS);
 347                         btrfs_clear_opt(ctx->mount_opt, NODATACOW);
 348                         btrfs_clear_opt(ctx->mount_opt, NODATASUM);
 349                 } else if (strncmp(param->string, "zlib", 4) == 0) {
 350                         ctx->compress_type = BTRFS_COMPRESS_ZLIB;
 351                         ctx->compress_level =
 352                                 btrfs_compress_str2level(BTRFS_COMPRESS_ZLIB,
 353                                                          param->string + 4);
 354                         btrfs_set_opt(ctx->mount_opt, COMPRESS);
 355                         btrfs_clear_opt(ctx->mount_opt, NODATACOW);
 356                         btrfs_clear_opt(ctx->mount_opt, NODATASUM);
 357                 } else if (strncmp(param->string, "lzo", 3) == 0) {
 358                         ctx->compress_type = BTRFS_COMPRESS_LZO;
 359                         ctx->compress_level = 0;
 360                         btrfs_set_opt(ctx->mount_opt, COMPRESS);
 361                         btrfs_clear_opt(ctx->mount_opt, NODATACOW);
 362                         btrfs_clear_opt(ctx->mount_opt, NODATASUM);
 363                 } else if (strncmp(param->string, "zstd", 4) == 0) {
 364                         ctx->compress_type = BTRFS_COMPRESS_ZSTD;
 365                         ctx->compress_level =
 366                                 btrfs_compress_str2level(BTRFS_COMPRESS_ZSTD,
 367                                                          param->string + 4);
 368                         btrfs_set_opt(ctx->mount_opt, COMPRESS);
 369                         btrfs_clear_opt(ctx->mount_opt, NODATACOW);
 370                         btrfs_clear_opt(ctx->mount_opt, NODATASUM);
 371                 } else if (strncmp(param->string, "no", 2) == 0) {
 372                         ctx->compress_level = 0;
 373                         ctx->compress_type = 0;
 374                         btrfs_clear_opt(ctx->mount_opt, COMPRESS);
 375                         btrfs_clear_opt(ctx->mount_opt, FORCE_COMPRESS);
 376                 } else {
 377                         btrfs_err(NULL, "unrecognized compression value %s",
 378                                   param->string);
 379                         return -EINVAL;
 380                 }
 381                 break;
 382         case Opt_ssd:
 383                 if (result.negated) {
 384                         btrfs_set_opt(ctx->mount_opt, NOSSD);
 385                         btrfs_clear_opt(ctx->mount_opt, SSD);
 386                         btrfs_clear_opt(ctx->mount_opt, SSD_SPREAD);
 387                 } else {
 388                         btrfs_set_opt(ctx->mount_opt, SSD);
 389                         btrfs_clear_opt(ctx->mount_opt, NOSSD);
 390                 }
 391                 break;
 392         case Opt_ssd_spread:
 393                 if (result.negated) {
 394                         btrfs_clear_opt(ctx->mount_opt, SSD_SPREAD);
 395                 } else {
 396                         btrfs_set_opt(ctx->mount_opt, SSD);
 397                         btrfs_set_opt(ctx->mount_opt, SSD_SPREAD);
 398                         btrfs_clear_opt(ctx->mount_opt, NOSSD);
 399                 }
 400                 break;
 401         case Opt_barrier:
 402                 if (result.negated)
 403                         btrfs_set_opt(ctx->mount_opt, NOBARRIER);
 404                 else
 405                         btrfs_clear_opt(ctx->mount_opt, NOBARRIER);
 406                 break;
 407         case Opt_thread_pool:
 408                 if (result.uint_32 == 0) {
 409                         btrfs_err(NULL, "invalid value 0 for thread_pool");
 410                         return -EINVAL;
 411                 }
 412                 ctx->thread_pool_size = result.uint_32;
 413                 break;
 414         case Opt_max_inline:
 415                 ctx->max_inline = memparse(param->string, NULL);
 416                 break;
 417         case Opt_acl:
 418                 if (result.negated) {
 419                         fc->sb_flags &= ~SB_POSIXACL;
 420                 } else {
 421 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 422                         fc->sb_flags |= SB_POSIXACL;
 423 #else
 424                         btrfs_err(NULL, "support for ACL not compiled in");
 425                         return -EINVAL;
 426 #endif
 427                 }
 428                 /*
 429                  * VFS limits the ability to toggle ACL on and off via remount,
 430                  * despite every file system allowing this.  This seems to be
 431                  * an oversight since we all do, but it'll fail if we're
 432                  * remounting.  So don't set the mask here, we'll check it in
 433                  * btrfs_reconfigure and do the toggling ourselves.
 434                  */
 435                 if (fc->purpose != FS_CONTEXT_FOR_RECONFIGURE)
 436                         fc->sb_flags_mask |= SB_POSIXACL;
 437                 break;
 438         case Opt_treelog:
 439                 if (result.negated)
 440                         btrfs_set_opt(ctx->mount_opt, NOTREELOG);
 441                 else
 442                         btrfs_clear_opt(ctx->mount_opt, NOTREELOG);
 443                 break;
 444         case Opt_nologreplay:
 445                 btrfs_warn(NULL,
 446                 "'nologreplay' is deprecated, use 'rescue=nologreplay' instead");
 447                 btrfs_set_opt(ctx->mount_opt, NOLOGREPLAY);
 448                 break;
 449         case Opt_norecovery:
 450                 btrfs_info(NULL,
 451 "'norecovery' is for compatibility only, recommended to use 'rescue=nologreplay'");
 452                 btrfs_set_opt(ctx->mount_opt, NOLOGREPLAY);
 453                 break;
 454         case Opt_flushoncommit:
 455                 if (result.negated)
 456                         btrfs_clear_opt(ctx->mount_opt, FLUSHONCOMMIT);
 457                 else
 458                         btrfs_set_opt(ctx->mount_opt, FLUSHONCOMMIT);
 459                 break;
 460         case Opt_ratio:
 461                 ctx->metadata_ratio = result.uint_32;
 462                 break;
 463         case Opt_discard:
 464                 if (result.negated) {
 465                         btrfs_clear_opt(ctx->mount_opt, DISCARD_SYNC);
 466                         btrfs_clear_opt(ctx->mount_opt, DISCARD_ASYNC);
 467                         btrfs_set_opt(ctx->mount_opt, NODISCARD);
 468                 } else {
 469                         btrfs_set_opt(ctx->mount_opt, DISCARD_SYNC);
 470                         btrfs_clear_opt(ctx->mount_opt, DISCARD_ASYNC);
 471                 }
 472                 break;
 473         case Opt_discard_mode:
 474                 switch (result.uint_32) {
 475                 case Opt_discard_sync:
 476                         btrfs_clear_opt(ctx->mount_opt, DISCARD_ASYNC);
 477                         btrfs_set_opt(ctx->mount_opt, DISCARD_SYNC);
 478                         break;
 479                 case Opt_discard_async:
 480                         btrfs_clear_opt(ctx->mount_opt, DISCARD_SYNC);
 481                         btrfs_set_opt(ctx->mount_opt, DISCARD_ASYNC);
 482                         break;
 483                 default:
 484                         btrfs_err(NULL, "unrecognized discard mode value %s",
 485                                   param->key);
 486                         return -EINVAL;
 487                 }
 488                 btrfs_clear_opt(ctx->mount_opt, NODISCARD);
 489                 break;
 490         case Opt_space_cache:
 491                 if (result.negated) {
 492                         btrfs_set_opt(ctx->mount_opt, NOSPACECACHE);
 493                         btrfs_clear_opt(ctx->mount_opt, SPACE_CACHE);
 494                         btrfs_clear_opt(ctx->mount_opt, FREE_SPACE_TREE);
 495                 } else {
 496                         btrfs_clear_opt(ctx->mount_opt, FREE_SPACE_TREE);
 497                         btrfs_set_opt(ctx->mount_opt, SPACE_CACHE);
 498                 }
 499                 break;
 500         case Opt_space_cache_version:
 501                 switch (result.uint_32) {
 502                 case Opt_space_cache_v1:
 503                         btrfs_set_opt(ctx->mount_opt, SPACE_CACHE);
 504                         btrfs_clear_opt(ctx->mount_opt, FREE_SPACE_TREE);
 505                         break;
 506                 case Opt_space_cache_v2:
 507                         btrfs_clear_opt(ctx->mount_opt, SPACE_CACHE);
 508                         btrfs_set_opt(ctx->mount_opt, FREE_SPACE_TREE);
 509                         break;
 510                 default:
 511                         btrfs_err(NULL, "unrecognized space_cache value %s",
 512                                   param->key);
 513                         return -EINVAL;
 514                 }
 515                 break;
 516         case Opt_rescan_uuid_tree:
 517                 btrfs_set_opt(ctx->mount_opt, RESCAN_UUID_TREE);
 518                 break;
 519         case Opt_clear_cache:
 520                 btrfs_set_opt(ctx->mount_opt, CLEAR_CACHE);
 521                 break;
 522         case Opt_user_subvol_rm_allowed:
 523                 btrfs_set_opt(ctx->mount_opt, USER_SUBVOL_RM_ALLOWED);
 524                 break;
 525         case Opt_enospc_debug:
 526                 if (result.negated)
 527                         btrfs_clear_opt(ctx->mount_opt, ENOSPC_DEBUG);
 528                 else
 529                         btrfs_set_opt(ctx->mount_opt, ENOSPC_DEBUG);
 530                 break;
 531         case Opt_defrag:
 532                 if (result.negated)
 533                         btrfs_clear_opt(ctx->mount_opt, AUTO_DEFRAG);
 534                 else
 535                         btrfs_set_opt(ctx->mount_opt, AUTO_DEFRAG);
 536                 break;
 537         case Opt_usebackuproot:
 538                 btrfs_warn(NULL,
 539                            "'usebackuproot' is deprecated, use 'rescue=usebackuproot' instead");
 540                 btrfs_set_opt(ctx->mount_opt, USEBACKUPROOT);
 541
 542                 /* If we're loading the backup roots we can't trust the space cache. */
 543                 btrfs_set_opt(ctx->mount_opt, CLEAR_CACHE);
 544                 break;
 545         case Opt_skip_balance:
 546                 btrfs_set_opt(ctx->mount_opt, SKIP_BALANCE);
 547                 break;
 548         case Opt_fatal_errors:
 549                 switch (result.uint_32) {
 550                 case Opt_fatal_errors_panic:
 551                         btrfs_set_opt(ctx->mount_opt, PANIC_ON_FATAL_ERROR);
 552                         break;
 553                 case Opt_fatal_errors_bug:
 554                         btrfs_clear_opt(ctx->mount_opt, PANIC_ON_FATAL_ERROR);
 555                         break;
 556                 default:
 557                         btrfs_err(NULL, "unrecognized fatal_errors value %s",
 558                                   param->key);
 559                         return -EINVAL;
 560                 }
 561                 break;
 562         case Opt_commit_interval:
 563                 ctx->commit_interval = result.uint_32;
 564                 if (ctx->commit_interval == 0)
 565                         ctx->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
 566                 break;
 567         case Opt_rescue:
 568                 switch (result.uint_32) {
 569                 case Opt_rescue_usebackuproot:
 570                         btrfs_set_opt(ctx->mount_opt, USEBACKUPROOT);
 571                         break;
 572                 case Opt_rescue_nologreplay:
 573                         btrfs_set_opt(ctx->mount_opt, NOLOGREPLAY);
 574                         break;
 575                 case Opt_rescue_ignorebadroots:
 576                         btrfs_set_opt(ctx->mount_opt, IGNOREBADROOTS);
 577                         break;
 578                 case Opt_rescue_ignoredatacsums:
 579                         btrfs_set_opt(ctx->mount_opt, IGNOREDATACSUMS);
 580                         break;
 581                 case Opt_rescue_ignoremetacsums:
 582                         btrfs_set_opt(ctx->mount_opt, IGNOREMETACSUMS);
 583                         break;
 584                 case Opt_rescue_ignoresuperflags:
 585                         btrfs_set_opt(ctx->mount_opt, IGNORESUPERFLAGS);
 586                         break;
 587                 case Opt_rescue_parameter_all:
 588                         btrfs_set_opt(ctx->mount_opt, IGNOREDATACSUMS);
 589                         btrfs_set_opt(ctx->mount_opt, IGNOREMETACSUMS);
 590                         btrfs_set_opt(ctx->mount_opt, IGNORESUPERFLAGS);
 591                         btrfs_set_opt(ctx->mount_opt, IGNOREBADROOTS);
 592                         btrfs_set_opt(ctx->mount_opt, NOLOGREPLAY);
 593                         break;
 594                 default:
 595                         btrfs_info(NULL, "unrecognized rescue option '%s'",
 596                                    param->key);
 597                         return -EINVAL;
 598                 }
 599                 break;
 600 #ifdef CONFIG_BTRFS_DEBUG
 601         case Opt_fragment:
 602                 switch (result.uint_32) {
 603                 case Opt_fragment_parameter_all:
 604                         btrfs_set_opt(ctx->mount_opt, FRAGMENT_DATA);
 605                         btrfs_set_opt(ctx->mount_opt, FRAGMENT_METADATA);
 606                         break;
 607                 case Opt_fragment_parameter_metadata:
 608                         btrfs_set_opt(ctx->mount_opt, FRAGMENT_METADATA);
 609                         break;
 610                 case Opt_fragment_parameter_data:
 611                         btrfs_set_opt(ctx->mount_opt, FRAGMENT_DATA);
 612                         break;
 613                 default:
 614                         btrfs_info(NULL, "unrecognized fragment option '%s'",
 615                                    param->key);
 616                         return -EINVAL;
 617                 }
 618                 break;
 619 #endif
 620 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 621         case Opt_ref_verify:
 622                 btrfs_set_opt(ctx->mount_opt, REF_VERIFY);
 623                 break;
 624 #endif
 625         default:
 626                 btrfs_err(NULL, "unrecognized mount option '%s'", param->key);
 627                 return -EINVAL;
 628         }
 629
 630         return 0;
 631 }
 632
 633 /*
 634  * Some options only have meaning at mount time and shouldn't persist across
 635  * remounts, or be displayed. Clear these at the end of mount and remount code
 636  * paths.
 637  */
 638 static void btrfs_clear_oneshot_options(struct btrfs_fs_info *fs_info)
 639 {
 640         btrfs_clear_opt(fs_info->mount_opt, USEBACKUPROOT);
 641         btrfs_clear_opt(fs_info->mount_opt, CLEAR_CACHE);
 642         btrfs_clear_opt(fs_info->mount_opt, NOSPACECACHE);
 643 }
 644
 645 static bool check_ro_option(const struct btrfs_fs_info *fs_info,
 646                             unsigned long long mount_opt, unsigned long long opt,
 647                             const char *opt_name)
 648 {
 649         if (mount_opt & opt) {
 650                 btrfs_err(fs_info, "%s must be used with ro mount option",
 651                           opt_name);
 652                 return true;
 653         }
 654         return false;
 655 }
 656
 657 bool btrfs_check_options(const struct btrfs_fs_info *info,
 658                          unsigned long long *mount_opt,
 659                          unsigned long flags)
 660 {
 661         bool ret = true;
 662
 663         if (!(flags & SB_RDONLY) &&
 664             (check_ro_option(info, *mount_opt, BTRFS_MOUNT_NOLOGREPLAY, "nologreplay") ||
 665              check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREBADROOTS, "ignorebadroots") ||
 666              check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREDATACSUMS, "ignoredatacsums") ||
 667              check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNOREMETACSUMS, "ignoremetacsums") ||
 668              check_ro_option(info, *mount_opt, BTRFS_MOUNT_IGNORESUPERFLAGS, "ignoresuperflags")))
 669                 ret = false;
 670
 671         if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) &&
 672             !btrfs_raw_test_opt(*mount_opt, FREE_SPACE_TREE) &&
 673             !btrfs_raw_test_opt(*mount_opt, CLEAR_CACHE)) {
 674                 btrfs_err(info, "cannot disable free-space-tree");
 675                 ret = false;
 676         }
 677         if (btrfs_fs_compat_ro(info, BLOCK_GROUP_TREE) &&
 678              !btrfs_raw_test_opt(*mount_opt, FREE_SPACE_TREE)) {
 679                 btrfs_err(info, "cannot disable free-space-tree with block-group-tree feature");
 680                 ret = false;
 681         }
 682
 683         if (btrfs_check_mountopts_zoned(info, mount_opt))
 684                 ret = false;
 685
 686         if (!test_bit(BTRFS_FS_STATE_REMOUNTING, &info->fs_state)) {
 687                 if (btrfs_raw_test_opt(*mount_opt, SPACE_CACHE)) {
 688                         btrfs_info(info, "disk space caching is enabled");
 689                         btrfs_warn(info,
 690 "space cache v1 is being deprecated and will be removed in a future release, please use -o space_cache=v2");
 691                 }
 692                 if (btrfs_raw_test_opt(*mount_opt, FREE_SPACE_TREE))
 693                         btrfs_info(info, "using free-space-tree");
 694         }
 695
 696         return ret;
 697 }
 698
 699 /*
 700  * This is subtle, we only call this during open_ctree().  We need to pre-load
 701  * the mount options with the on-disk settings.  Before the new mount API took
 702  * effect we would do this on mount and remount.  With the new mount API we'll
 703  * only do this on the initial mount.
 704  *
 705  * This isn't a change in behavior, because we're using the current state of the
 706  * file system to set the current mount options.  If you mounted with special
 707  * options to disable these features and then remounted we wouldn't revert the
 708  * settings, because mounting without these features cleared the on-disk
 709  * settings, so this being called on re-mount is not needed.
 710  */
 711 void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info)
 712 {
 713         if (fs_info->sectorsize < PAGE_SIZE) {
 714                 btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
 715                 if (!btrfs_test_opt(fs_info, FREE_SPACE_TREE)) {
 716                         btrfs_info(fs_info,
 717                                    "forcing free space tree for sector size %u with page size %lu",
 718                                    fs_info->sectorsize, PAGE_SIZE);
 719                         btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
 720                 }
 721         }
 722
 723         /*
 724          * At this point our mount options are populated, so we only mess with
 725          * these settings if we don't have any settings already.
 726          */
 727         if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
 728                 return;
 729
 730         if (btrfs_is_zoned(fs_info) &&
 731             btrfs_free_space_cache_v1_active(fs_info)) {
 732                 btrfs_info(fs_info, "zoned: clearing existing space cache");
 733                 btrfs_set_super_cache_generation(fs_info->super_copy, 0);
 734                 return;
 735         }
 736
 737         if (btrfs_test_opt(fs_info, SPACE_CACHE))
 738                 return;
 739
 740         if (btrfs_test_opt(fs_info, NOSPACECACHE))
 741                 return;
 742
 743         /*
 744          * At this point we don't have explicit options set by the user, set
 745          * them ourselves based on the state of the file system.
 746          */
 747         if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
 748                 btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
 749         else if (btrfs_free_space_cache_v1_active(fs_info))
 750                 btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE);
 751 }
 752
 753 static void set_device_specific_options(struct btrfs_fs_info *fs_info)
 754 {
 755         if (!btrfs_test_opt(fs_info, NOSSD) &&
 756             !fs_info->fs_devices->rotating)
 757                 btrfs_set_opt(fs_info->mount_opt, SSD);
 758
 759         /*
 760          * For devices supporting discard turn on discard=async automatically,
 761          * unless it's already set or disabled. This could be turned off by
 762          * nodiscard for the same mount.
 763          *
 764          * The zoned mode piggy backs on the discard functionality for
 765          * resetting a zone. There is no reason to delay the zone reset as it is
 766          * fast enough. So, do not enable async discard for zoned mode.
 767          */
 768         if (!(btrfs_test_opt(fs_info, DISCARD_SYNC) ||
 769               btrfs_test_opt(fs_info, DISCARD_ASYNC) ||
 770               btrfs_test_opt(fs_info, NODISCARD)) &&
 771             fs_info->fs_devices->discardable &&
 772             !btrfs_is_zoned(fs_info))
 773                 btrfs_set_opt(fs_info->mount_opt, DISCARD_ASYNC);
 774 }
 775
 776 char *btrfs_get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 777                                           u64 subvol_objectid)
 778 {
 779         struct btrfs_root *root = fs_info->tree_root;
 780         struct btrfs_root *fs_root = NULL;
 781         struct btrfs_root_ref *root_ref;
 782         struct btrfs_inode_ref *inode_ref;
 783         struct btrfs_key key;
 784         struct btrfs_path *path = NULL;
 785         char *name = NULL, *ptr;
 786         u64 dirid;
 787         int len;
 788         int ret;
 789
 790         path = btrfs_alloc_path();
 791         if (!path) {
 792                 ret = -ENOMEM;
 793                 goto err;
 794         }
 795
 796         name = kmalloc(PATH_MAX, GFP_KERNEL);
 797         if (!name) {
 798                 ret = -ENOMEM;
 799                 goto err;
 800         }
 801         ptr = name + PATH_MAX - 1;
 802         ptr[0] = '\0';
 803
 804         /*
 805          * Walk up the subvolume trees in the tree of tree roots by root
 806          * backrefs until we hit the top-level subvolume.
 807          */
 808         while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
 809                 key.objectid = subvol_objectid;
 810                 key.type = BTRFS_ROOT_BACKREF_KEY;
 811                 key.offset = (u64)-1;
 812
 813                 ret = btrfs_search_backwards(root, &key, path);
 814                 if (ret < 0) {
 815                         goto err;
 816                 } else if (ret > 0) {
 817                         ret = -ENOENT;
 818                         goto err;
 819                 }
 820
 821                 subvol_objectid = key.offset;
 822
 823                 root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 824                                           struct btrfs_root_ref);
 825                 len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
 826                 ptr -= len + 1;
 827                 if (ptr < name) {
 828                         ret = -ENAMETOOLONG;
 829                         goto err;
 830                 }
 831                 read_extent_buffer(path->nodes[0], ptr + 1,
 832                                    (unsigned long)(root_ref + 1), len);
 833                 ptr[0] = '/';
 834                 dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
 835                 btrfs_release_path(path);
 836
 837                 fs_root = btrfs_get_fs_root(fs_info, subvol_objectid, true);
 838                 if (IS_ERR(fs_root)) {
 839                         ret = PTR_ERR(fs_root);
 840                         fs_root = NULL;
 841                         goto err;
 842                 }
 843
 844                 /*
 845                  * Walk up the filesystem tree by inode refs until we hit the
 846                  * root directory.
 847                  */
 848                 while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
 849                         key.objectid = dirid;
 850                         key.type = BTRFS_INODE_REF_KEY;
 851                         key.offset = (u64)-1;
 852
 853                         ret = btrfs_search_backwards(fs_root, &key, path);
 854                         if (ret < 0) {
 855                                 goto err;
 856                         } else if (ret > 0) {
 857                                 ret = -ENOENT;
 858                                 goto err;
 859                         }
 860
 861                         dirid = key.offset;
 862
 863                         inode_ref = btrfs_item_ptr(path->nodes[0],
 864                                                    path->slots[0],
 865                                                    struct btrfs_inode_ref);
 866                         len = btrfs_inode_ref_name_len(path->nodes[0],
 867                                                        inode_ref);
 868                         ptr -= len + 1;
 869                         if (ptr < name) {
 870                                 ret = -ENAMETOOLONG;
 871                                 goto err;
 872                         }
 873                         read_extent_buffer(path->nodes[0], ptr + 1,
 874                                            (unsigned long)(inode_ref + 1), len);
 875                         ptr[0] = '/';
 876                         btrfs_release_path(path);
 877                 }
 878                 btrfs_put_root(fs_root);
 879                 fs_root = NULL;
 880         }
 881
 882         btrfs_free_path(path);
 883         if (ptr == name + PATH_MAX - 1) {
 884                 name[0] = '/';
 885                 name[1] = '\0';
 886         } else {
 887                 memmove(name, ptr, name + PATH_MAX - ptr);
 888         }
 889         return name;
 890
 891 err:
 892         btrfs_put_root(fs_root);
 893         btrfs_free_path(path);
 894         kfree(name);
 895         return ERR_PTR(ret);
 896 }
 897
 898 static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
 899 {
 900         struct btrfs_root *root = fs_info->tree_root;
 901         struct btrfs_dir_item *di;
 902         struct btrfs_path *path;
 903         struct btrfs_key location;
 904         struct fscrypt_str name = FSTR_INIT("default", 7);
 905         u64 dir_id;
 906
 907         path = btrfs_alloc_path();
 908         if (!path)
 909                 return -ENOMEM;
 910
 911         /*
 912          * Find the "default" dir item which points to the root item that we
 913          * will mount by default if we haven't been given a specific subvolume
 914          * to mount.
 915          */
 916         dir_id = btrfs_super_root_dir(fs_info->super_copy);
 917         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, &name, 0);
 918         if (IS_ERR(di)) {
 919                 btrfs_free_path(path);
 920                 return PTR_ERR(di);
 921         }
 922         if (!di) {
 923                 /*
 924                  * Ok the default dir item isn't there.  This is weird since
 925                  * it's always been there, but don't freak out, just try and
 926                  * mount the top-level subvolume.
 927                  */
 928                 btrfs_free_path(path);
 929                 *objectid = BTRFS_FS_TREE_OBJECTID;
 930                 return 0;
 931         }
 932
 933         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 934         btrfs_free_path(path);
 935         *objectid = location.objectid;
 936         return 0;
 937 }
 938
 939 static int btrfs_fill_super(struct super_block *sb,
 940                             struct btrfs_fs_devices *fs_devices,
 941                             void *data)
 942 {
 943         struct inode *inode;
 944         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 945         int err;
 946
 947         sb->s_maxbytes = MAX_LFS_FILESIZE;
 948         sb->s_magic = BTRFS_SUPER_MAGIC;
 949         sb->s_op = &btrfs_super_ops;
 950         sb->s_d_op = &btrfs_dentry_operations;
 951         sb->s_export_op = &btrfs_export_ops;
 952 #ifdef CONFIG_FS_VERITY
 953         sb->s_vop = &btrfs_verityops;
 954 #endif
 955         sb->s_xattr = btrfs_xattr_handlers;
 956         sb->s_time_gran = 1;
 957         sb->s_iflags |= SB_I_CGROUPWB;
 958
 959         err = super_setup_bdi(sb);
 960         if (err) {
 961                 btrfs_err(fs_info, "super_setup_bdi failed");
 962                 return err;
 963         }
 964
 965         err = open_ctree(sb, fs_devices, (char *)data);
 966         if (err) {
 967                 btrfs_err(fs_info, "open_ctree failed");
 968                 return err;
 969         }
 970
 971         inode = btrfs_iget(BTRFS_FIRST_FREE_OBJECTID, fs_info->fs_root);
 972         if (IS_ERR(inode)) {
 973                 err = PTR_ERR(inode);
 974                 btrfs_handle_fs_error(fs_info, err, NULL);
 975                 goto fail_close;
 976         }
 977
 978         sb->s_root = d_make_root(inode);
 979         if (!sb->s_root) {
 980                 err = -ENOMEM;
 981                 goto fail_close;
 982         }
 983
 984         sb->s_flags |= SB_ACTIVE;
 985         return 0;
 986
 987 fail_close:
 988         close_ctree(fs_info);
 989         return err;
 990 }
 991
 992 int btrfs_sync_fs(struct super_block *sb, int wait)
 993 {
 994         struct btrfs_trans_handle *trans;
 995         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 996         struct btrfs_root *root = fs_info->tree_root;
 997
 998         trace_btrfs_sync_fs(fs_info, wait);
 999
1000         if (!wait) {
1001                 filemap_flush(fs_info->btree_inode->i_mapping);
1002                 return 0;
1003         }
1004
1005         btrfs_wait_ordered_roots(fs_info, U64_MAX, NULL);
1006
1007         trans = btrfs_attach_transaction_barrier(root);
1008         if (IS_ERR(trans)) {
1009                 /* no transaction, don't bother */
1010                 if (PTR_ERR(trans) == -ENOENT) {
1011                         /*
1012                          * Exit unless we have some pending changes
1013                          * that need to go through commit
1014                          */
1015                         if (!test_bit(BTRFS_FS_NEED_TRANS_COMMIT,
1016                                       &fs_info->flags))
1017                                 return 0;
1018                         /*
1019                          * A non-blocking test if the fs is frozen. We must not
1020                          * start a new transaction here otherwise a deadlock
1021                          * happens. The pending operations are delayed to the
1022                          * next commit after thawing.
1023                          */
1024                         if (sb_start_write_trylock(sb))
1025                                 sb_end_write(sb);
1026                         else
1027                                 return 0;
1028                         trans = btrfs_start_transaction(root, 0);
1029                 }
1030                 if (IS_ERR(trans))
1031                         return PTR_ERR(trans);
1032         }
1033         return btrfs_commit_transaction(trans);
1034 }
1035
1036 static void print_rescue_option(struct seq_file *seq, const char *s, bool *printed)
1037 {
1038         seq_printf(seq, "%s%s", (*printed) ? ":" : ",rescue=", s);
1039         *printed = true;
1040 }
1041
1042 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1043 {
1044         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1045         const char *compress_type;
1046         const char *subvol_name;
1047         bool printed = false;
1048
1049         if (btrfs_test_opt(info, DEGRADED))
1050                 seq_puts(seq, ",degraded");
1051         if (btrfs_test_opt(info, NODATASUM))
1052                 seq_puts(seq, ",nodatasum");
1053         if (btrfs_test_opt(info, NODATACOW))
1054                 seq_puts(seq, ",nodatacow");
1055         if (btrfs_test_opt(info, NOBARRIER))
1056                 seq_puts(seq, ",nobarrier");
1057         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1058                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
1059         if (info->thread_pool_size !=  min_t(unsigned long,
1060                                              num_online_cpus() + 2, 8))
1061                 seq_printf(seq, ",thread_pool=%u", info->thread_pool_size);
1062         if (btrfs_test_opt(info, COMPRESS)) {
1063                 compress_type = btrfs_compress_type2str(info->compress_type);
1064                 if (btrfs_test_opt(info, FORCE_COMPRESS))
1065                         seq_printf(seq, ",compress-force=%s", compress_type);
1066                 else
1067                         seq_printf(seq, ",compress=%s", compress_type);
1068                 if (info->compress_level)
1069                         seq_printf(seq, ":%d", info->compress_level);
1070         }
1071         if (btrfs_test_opt(info, NOSSD))
1072                 seq_puts(seq, ",nossd");
1073         if (btrfs_test_opt(info, SSD_SPREAD))
1074                 seq_puts(seq, ",ssd_spread");
1075         else if (btrfs_test_opt(info, SSD))
1076                 seq_puts(seq, ",ssd");
1077         if (btrfs_test_opt(info, NOTREELOG))
1078                 seq_puts(seq, ",notreelog");
1079         if (btrfs_test_opt(info, NOLOGREPLAY))
1080                 print_rescue_option(seq, "nologreplay", &printed);
1081         if (btrfs_test_opt(info, USEBACKUPROOT))
1082                 print_rescue_option(seq, "usebackuproot", &printed);
1083         if (btrfs_test_opt(info, IGNOREBADROOTS))
1084                 print_rescue_option(seq, "ignorebadroots", &printed);
1085         if (btrfs_test_opt(info, IGNOREDATACSUMS))
1086                 print_rescue_option(seq, "ignoredatacsums", &printed);
1087         if (btrfs_test_opt(info, IGNOREMETACSUMS))
1088                 print_rescue_option(seq, "ignoremetacsums", &printed);
1089         if (btrfs_test_opt(info, IGNORESUPERFLAGS))
1090                 print_rescue_option(seq, "ignoresuperflags", &printed);
1091         if (btrfs_test_opt(info, FLUSHONCOMMIT))
1092                 seq_puts(seq, ",flushoncommit");
1093         if (btrfs_test_opt(info, DISCARD_SYNC))
1094                 seq_puts(seq, ",discard");
1095         if (btrfs_test_opt(info, DISCARD_ASYNC))
1096                 seq_puts(seq, ",discard=async");
1097         if (!(info->sb->s_flags & SB_POSIXACL))
1098                 seq_puts(seq, ",noacl");
1099         if (btrfs_free_space_cache_v1_active(info))
1100                 seq_puts(seq, ",space_cache");
1101         else if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
1102                 seq_puts(seq, ",space_cache=v2");
1103         else
1104                 seq_puts(seq, ",nospace_cache");
1105         if (btrfs_test_opt(info, RESCAN_UUID_TREE))
1106                 seq_puts(seq, ",rescan_uuid_tree");
1107         if (btrfs_test_opt(info, CLEAR_CACHE))
1108                 seq_puts(seq, ",clear_cache");
1109         if (btrfs_test_opt(info, USER_SUBVOL_RM_ALLOWED))
1110                 seq_puts(seq, ",user_subvol_rm_allowed");
1111         if (btrfs_test_opt(info, ENOSPC_DEBUG))
1112                 seq_puts(seq, ",enospc_debug");
1113         if (btrfs_test_opt(info, AUTO_DEFRAG))
1114                 seq_puts(seq, ",autodefrag");
1115         if (btrfs_test_opt(info, SKIP_BALANCE))
1116                 seq_puts(seq, ",skip_balance");
1117         if (info->metadata_ratio)
1118                 seq_printf(seq, ",metadata_ratio=%u", info->metadata_ratio);
1119         if (btrfs_test_opt(info, PANIC_ON_FATAL_ERROR))
1120                 seq_puts(seq, ",fatal_errors=panic");
1121         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1122                 seq_printf(seq, ",commit=%u", info->commit_interval);
1123 #ifdef CONFIG_BTRFS_DEBUG
1124         if (btrfs_test_opt(info, FRAGMENT_DATA))
1125                 seq_puts(seq, ",fragment=data");
1126         if (btrfs_test_opt(info, FRAGMENT_METADATA))
1127                 seq_puts(seq, ",fragment=metadata");
1128 #endif
1129         if (btrfs_test_opt(info, REF_VERIFY))
1130                 seq_puts(seq, ",ref_verify");
1131         seq_printf(seq, ",subvolid=%llu", btrfs_root_id(BTRFS_I(d_inode(dentry))->root));
1132         subvol_name = btrfs_get_subvol_name_from_objectid(info,
1133                         btrfs_root_id(BTRFS_I(d_inode(dentry))->root));
1134         if (!IS_ERR(subvol_name)) {
1135                 seq_puts(seq, ",subvol=");
1136                 seq_escape(seq, subvol_name, " \t\n\\");
1137                 kfree(subvol_name);
1138         }
1139         return 0;
1140 }
1141
1142 /*
1143  * subvolumes are identified by ino 256
1144  */
1145 static inline int is_subvolume_inode(struct inode *inode)
1146 {
1147         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1148                 return 1;
1149         return 0;
1150 }
1151
1152 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
1153                                    struct vfsmount *mnt)
1154 {
1155         struct dentry *root;
1156         int ret;
1157
1158         if (!subvol_name) {
1159                 if (!subvol_objectid) {
1160                         ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
1161                                                           &subvol_objectid);
1162                         if (ret) {
1163                                 root = ERR_PTR(ret);
1164                                 goto out;
1165                         }
1166                 }
1167                 subvol_name = btrfs_get_subvol_name_from_objectid(
1168                                         btrfs_sb(mnt->mnt_sb), subvol_objectid);
1169                 if (IS_ERR(subvol_name)) {
1170                         root = ERR_CAST(subvol_name);
1171                         subvol_name = NULL;
1172                         goto out;
1173                 }
1174
1175         }
1176
1177         root = mount_subtree(mnt, subvol_name);
1178         /* mount_subtree() drops our reference on the vfsmount. */
1179         mnt = NULL;
1180
1181         if (!IS_ERR(root)) {
1182                 struct super_block *s = root->d_sb;
1183                 struct btrfs_fs_info *fs_info = btrfs_sb(s);
1184                 struct inode *root_inode = d_inode(root);
1185                 u64 root_objectid = btrfs_root_id(BTRFS_I(root_inode)->root);
1186
1187                 ret = 0;
1188                 if (!is_subvolume_inode(root_inode)) {
1189                         btrfs_err(fs_info, "'%s' is not a valid subvolume",
1190                                subvol_name);
1191                         ret = -EINVAL;
1192                 }
1193                 if (subvol_objectid && root_objectid != subvol_objectid) {
1194                         /*
1195                          * This will also catch a race condition where a
1196                          * subvolume which was passed by ID is renamed and
1197                          * another subvolume is renamed over the old location.
1198                          */
1199                         btrfs_err(fs_info,
1200                                   "subvol '%s' does not match subvolid %llu",
1201                                   subvol_name, subvol_objectid);
1202                         ret = -EINVAL;
1203                 }
1204                 if (ret) {
1205                         dput(root);
1206                         root = ERR_PTR(ret);
1207                         deactivate_locked_super(s);
1208                 }
1209         }
1210
1211 out:
1212         mntput(mnt);
1213         kfree(subvol_name);
1214         return root;
1215 }
1216
1217 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1218                                      u32 new_pool_size, u32 old_pool_size)
1219 {
1220         if (new_pool_size == old_pool_size)
1221                 return;
1222
1223         fs_info->thread_pool_size = new_pool_size;
1224
1225         btrfs_info(fs_info, "resize thread pool %d -> %d",
1226                old_pool_size, new_pool_size);
1227
1228         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1229         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1230         btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1231         workqueue_set_max_active(fs_info->endio_workers, new_pool_size);
1232         workqueue_set_max_active(fs_info->endio_meta_workers, new_pool_size);
1233         btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1234         btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1235         btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1236 }
1237
1238 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1239                                        unsigned long long old_opts, int flags)
1240 {
1241         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1242             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1243              (flags & SB_RDONLY))) {
1244                 /* wait for any defraggers to finish */
1245                 wait_event(fs_info->transaction_wait,
1246                            (atomic_read(&fs_info->defrag_running) == 0));
1247                 if (flags & SB_RDONLY)
1248                         sync_filesystem(fs_info->sb);
1249         }
1250 }
1251
1252 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1253                                          unsigned long long old_opts)
1254 {
1255         const bool cache_opt = btrfs_test_opt(fs_info, SPACE_CACHE);
1256
1257         /*
1258          * We need to cleanup all defragable inodes if the autodefragment is
1259          * close or the filesystem is read only.
1260          */
1261         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1262             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) || sb_rdonly(fs_info->sb))) {
1263                 btrfs_cleanup_defrag_inodes(fs_info);
1264         }
1265
1266         /* If we toggled discard async */
1267         if (!btrfs_raw_test_opt(old_opts, DISCARD_ASYNC) &&
1268             btrfs_test_opt(fs_info, DISCARD_ASYNC))
1269                 btrfs_discard_resume(fs_info);
1270         else if (btrfs_raw_test_opt(old_opts, DISCARD_ASYNC) &&
1271                  !btrfs_test_opt(fs_info, DISCARD_ASYNC))
1272                 btrfs_discard_cleanup(fs_info);
1273
1274         /* If we toggled space cache */
1275         if (cache_opt != btrfs_free_space_cache_v1_active(fs_info))
1276                 btrfs_set_free_space_cache_v1_active(fs_info, cache_opt);
1277 }
1278
1279 static int btrfs_remount_rw(struct btrfs_fs_info *fs_info)
1280 {
1281         int ret;
1282
1283         if (BTRFS_FS_ERROR(fs_info)) {
1284                 btrfs_err(fs_info,
1285                           "remounting read-write after error is not allowed");
1286                 return -EINVAL;
1287         }
1288
1289         if (fs_info->fs_devices->rw_devices == 0)
1290                 return -EACCES;
1291
1292         if (!btrfs_check_rw_degradable(fs_info, NULL)) {
1293                 btrfs_warn(fs_info,
1294                            "too many missing devices, writable remount is not allowed");
1295                 return -EACCES;
1296         }
1297
1298         if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1299                 btrfs_warn(fs_info,
1300                            "mount required to replay tree-log, cannot remount read-write");
1301                 return -EINVAL;
1302         }
1303
1304         /*
1305          * NOTE: when remounting with a change that does writes, don't put it
1306          * anywhere above this point, as we are not sure to be safe to write
1307          * until we pass the above checks.
1308          */
1309         ret = btrfs_start_pre_rw_mount(fs_info);
1310         if (ret)
1311                 return ret;
1312
1313         btrfs_clear_sb_rdonly(fs_info->sb);
1314
1315         set_bit(BTRFS_FS_OPEN, &fs_info->flags);
1316
1317         /*
1318          * If we've gone from readonly -> read-write, we need to get our
1319          * sync/async discard lists in the right state.
1320          */
1321         btrfs_discard_resume(fs_info);
1322
1323         return 0;
1324 }
1325
1326 static int btrfs_remount_ro(struct btrfs_fs_info *fs_info)
1327 {
1328         /*
1329          * This also happens on 'umount -rf' or on shutdown, when the
1330          * filesystem is busy.
1331          */
1332         cancel_work_sync(&fs_info->async_reclaim_work);
1333         cancel_work_sync(&fs_info->async_data_reclaim_work);
1334
1335         btrfs_discard_cleanup(fs_info);
1336
1337         /* Wait for the uuid_scan task to finish */
1338         down(&fs_info->uuid_tree_rescan_sem);
1339         /* Avoid complains from lockdep et al. */
1340         up(&fs_info->uuid_tree_rescan_sem);
1341
1342         btrfs_set_sb_rdonly(fs_info->sb);
1343
1344         /*
1345          * Setting SB_RDONLY will put the cleaner thread to sleep at the next
1346          * loop if it's already active.  If it's already asleep, we'll leave
1347          * unused block groups on disk until we're mounted read-write again
1348          * unless we clean them up here.
1349          */
1350         btrfs_delete_unused_bgs(fs_info);
1351
1352         /*
1353          * The cleaner task could be already running before we set the flag
1354          * BTRFS_FS_STATE_RO (and SB_RDONLY in the superblock).  We must make
1355          * sure that after we finish the remount, i.e. after we call
1356          * btrfs_commit_super(), the cleaner can no longer start a transaction
1357          * - either because it was dropping a dead root, running delayed iputs
1358          *   or deleting an unused block group (the cleaner picked a block
1359          *   group from the list of unused block groups before we were able to
1360          *   in the previous call to btrfs_delete_unused_bgs()).
1361          */
1362         wait_on_bit(&fs_info->flags, BTRFS_FS_CLEANER_RUNNING, TASK_UNINTERRUPTIBLE);
1363
1364         /*
1365          * We've set the superblock to RO mode, so we might have made the
1366          * cleaner task sleep without running all pending delayed iputs. Go
1367          * through all the delayed iputs here, so that if an unmount happens
1368          * without remounting RW we don't end up at finishing close_ctree()
1369          * with a non-empty list of delayed iputs.
1370          */
1371         btrfs_run_delayed_iputs(fs_info);
1372
1373         btrfs_dev_replace_suspend_for_unmount(fs_info);
1374         btrfs_scrub_cancel(fs_info);
1375         btrfs_pause_balance(fs_info);
1376
1377         /*
1378          * Pause the qgroup rescan worker if it is running. We don't want it to
1379          * be still running after we are in RO mode, as after that, by the time
1380          * we unmount, it might have left a transaction open, so we would leak
1381          * the transaction and/or crash.
1382          */
1383         btrfs_qgroup_wait_for_completion(fs_info, false);
1384
1385         return btrfs_commit_super(fs_info);
1386 }
1387
1388 static void btrfs_ctx_to_info(struct btrfs_fs_info *fs_info, struct btrfs_fs_context *ctx)
1389 {
1390         fs_info->max_inline = ctx->max_inline;
1391         fs_info->commit_interval = ctx->commit_interval;
1392         fs_info->metadata_ratio = ctx->metadata_ratio;
1393         fs_info->thread_pool_size = ctx->thread_pool_size;
1394         fs_info->mount_opt = ctx->mount_opt;
1395         fs_info->compress_type = ctx->compress_type;
1396         fs_info->compress_level = ctx->compress_level;
1397 }
1398
1399 static void btrfs_info_to_ctx(struct btrfs_fs_info *fs_info, struct btrfs_fs_context *ctx)
1400 {
1401         ctx->max_inline = fs_info->max_inline;
1402         ctx->commit_interval = fs_info->commit_interval;
1403         ctx->metadata_ratio = fs_info->metadata_ratio;
1404         ctx->thread_pool_size = fs_info->thread_pool_size;
1405         ctx->mount_opt = fs_info->mount_opt;
1406         ctx->compress_type = fs_info->compress_type;
1407         ctx->compress_level = fs_info->compress_level;
1408 }
1409
1410 #define btrfs_info_if_set(fs_info, old_ctx, opt, fmt, args...)                  \
1411 do {                                                                            \
1412         if ((!old_ctx || !btrfs_raw_test_opt(old_ctx->mount_opt, opt)) &&       \
1413             btrfs_raw_test_opt(fs_info->mount_opt, opt))                        \
1414                 btrfs_info(fs_info, fmt, ##args);                               \
1415 } while (0)
1416
1417 #define btrfs_info_if_unset(fs_info, old_ctx, opt, fmt, args...)        \
1418 do {                                                                    \
1419         if ((old_ctx && btrfs_raw_test_opt(old_ctx->mount_opt, opt)) && \
1420             !btrfs_raw_test_opt(fs_info->mount_opt, opt))               \
1421                 btrfs_info(fs_info, fmt, ##args);                       \
1422 } while (0)
1423
1424 static void btrfs_emit_options(struct btrfs_fs_info *info,
1425                                struct btrfs_fs_context *old)
1426 {
1427         btrfs_info_if_set(info, old, NODATASUM, "setting nodatasum");
1428         btrfs_info_if_set(info, old, DEGRADED, "allowing degraded mounts");
1429         btrfs_info_if_set(info, old, NODATASUM, "setting nodatasum");
1430         btrfs_info_if_set(info, old, SSD, "enabling ssd optimizations");
1431         btrfs_info_if_set(info, old, SSD_SPREAD, "using spread ssd allocation scheme");
1432         btrfs_info_if_set(info, old, NOBARRIER, "turning off barriers");
1433         btrfs_info_if_set(info, old, NOTREELOG, "disabling tree log");
1434         btrfs_info_if_set(info, old, NOLOGREPLAY, "disabling log replay at mount time");
1435         btrfs_info_if_set(info, old, FLUSHONCOMMIT, "turning on flush-on-commit");
1436         btrfs_info_if_set(info, old, DISCARD_SYNC, "turning on sync discard");
1437         btrfs_info_if_set(info, old, DISCARD_ASYNC, "turning on async discard");
1438         btrfs_info_if_set(info, old, FREE_SPACE_TREE, "enabling free space tree");
1439         btrfs_info_if_set(info, old, SPACE_CACHE, "enabling disk space caching");
1440         btrfs_info_if_set(info, old, CLEAR_CACHE, "force clearing of disk cache");
1441         btrfs_info_if_set(info, old, AUTO_DEFRAG, "enabling auto defrag");
1442         btrfs_info_if_set(info, old, FRAGMENT_DATA, "fragmenting data");
1443         btrfs_info_if_set(info, old, FRAGMENT_METADATA, "fragmenting metadata");
1444         btrfs_info_if_set(info, old, REF_VERIFY, "doing ref verification");
1445         btrfs_info_if_set(info, old, USEBACKUPROOT, "trying to use backup root at mount time");
1446         btrfs_info_if_set(info, old, IGNOREBADROOTS, "ignoring bad roots");
1447         btrfs_info_if_set(info, old, IGNOREDATACSUMS, "ignoring data csums");
1448         btrfs_info_if_set(info, old, IGNOREMETACSUMS, "ignoring meta csums");
1449         btrfs_info_if_set(info, old, IGNORESUPERFLAGS, "ignoring unknown super block flags");
1450
1451         btrfs_info_if_unset(info, old, NODATACOW, "setting datacow");
1452         btrfs_info_if_unset(info, old, SSD, "not using ssd optimizations");
1453         btrfs_info_if_unset(info, old, SSD_SPREAD, "not using spread ssd allocation scheme");
1454         btrfs_info_if_unset(info, old, NOBARRIER, "turning off barriers");
1455         btrfs_info_if_unset(info, old, NOTREELOG, "enabling tree log");
1456         btrfs_info_if_unset(info, old, SPACE_CACHE, "disabling disk space caching");
1457         btrfs_info_if_unset(info, old, FREE_SPACE_TREE, "disabling free space tree");
1458         btrfs_info_if_unset(info, old, AUTO_DEFRAG, "disabling auto defrag");
1459         btrfs_info_if_unset(info, old, COMPRESS, "use no compression");
1460
1461         /* Did the compression settings change? */
1462         if (btrfs_test_opt(info, COMPRESS) &&
1463             (!old ||
1464              old->compress_type != info->compress_type ||
1465              old->compress_level != info->compress_level ||
1466              (!btrfs_raw_test_opt(old->mount_opt, FORCE_COMPRESS) &&
1467               btrfs_raw_test_opt(info->mount_opt, FORCE_COMPRESS)))) {
1468                 const char *compress_type = btrfs_compress_type2str(info->compress_type);
1469
1470                 btrfs_info(info, "%s %s compression, level %d",
1471                            btrfs_test_opt(info, FORCE_COMPRESS) ? "force" : "use",
1472                            compress_type, info->compress_level);
1473         }
1474
1475         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1476                 btrfs_info(info, "max_inline set to %llu", info->max_inline);
1477 }
1478
1479 static int btrfs_reconfigure(struct fs_context *fc)
1480 {
1481         struct super_block *sb = fc->root->d_sb;
1482         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1483         struct btrfs_fs_context *ctx = fc->fs_private;
1484         struct btrfs_fs_context old_ctx;
1485         int ret = 0;
1486         bool mount_reconfigure = (fc->s_fs_info != NULL);
1487
1488         btrfs_info_to_ctx(fs_info, &old_ctx);
1489
1490         /*
1491          * This is our "bind mount" trick, we don't want to allow the user to do
1492          * anything other than mount a different ro/rw and a different subvol,
1493          * all of the mount options should be maintained.
1494          */
1495         if (mount_reconfigure)
1496                 ctx->mount_opt = old_ctx.mount_opt;
1497
1498         sync_filesystem(sb);
1499         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1500
1501         if (!mount_reconfigure &&
1502             !btrfs_check_options(fs_info, &ctx->mount_opt, fc->sb_flags))
1503                 return -EINVAL;
1504
1505         ret = btrfs_check_features(fs_info, !(fc->sb_flags & SB_RDONLY));
1506         if (ret < 0)
1507                 return ret;
1508
1509         btrfs_ctx_to_info(fs_info, ctx);
1510         btrfs_remount_begin(fs_info, old_ctx.mount_opt, fc->sb_flags);
1511         btrfs_resize_thread_pool(fs_info, fs_info->thread_pool_size,
1512                                  old_ctx.thread_pool_size);
1513
1514         if ((bool)btrfs_test_opt(fs_info, FREE_SPACE_TREE) !=
1515             (bool)btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE) &&
1516             (!sb_rdonly(sb) || (fc->sb_flags & SB_RDONLY))) {
1517                 btrfs_warn(fs_info,
1518                 "remount supports changing free space tree only from RO to RW");
1519                 /* Make sure free space cache options match the state on disk. */
1520                 if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
1521                         btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
1522                         btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
1523                 }
1524                 if (btrfs_free_space_cache_v1_active(fs_info)) {
1525                         btrfs_clear_opt(fs_info->mount_opt, FREE_SPACE_TREE);
1526                         btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE);
1527                 }
1528         }
1529
1530         ret = 0;
1531         if (!sb_rdonly(sb) && (fc->sb_flags & SB_RDONLY))
1532                 ret = btrfs_remount_ro(fs_info);
1533         else if (sb_rdonly(sb) && !(fc->sb_flags & SB_RDONLY))
1534                 ret = btrfs_remount_rw(fs_info);
1535         if (ret)
1536                 goto restore;
1537
1538         /*
1539          * If we set the mask during the parameter parsing VFS would reject the
1540          * remount.  Here we can set the mask and the value will be updated
1541          * appropriately.
1542          */
1543         if ((fc->sb_flags & SB_POSIXACL) != (sb->s_flags & SB_POSIXACL))
1544                 fc->sb_flags_mask |= SB_POSIXACL;
1545
1546         btrfs_emit_options(fs_info, &old_ctx);
1547         wake_up_process(fs_info->transaction_kthread);
1548         btrfs_remount_cleanup(fs_info, old_ctx.mount_opt);
1549         btrfs_clear_oneshot_options(fs_info);
1550         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1551
1552         return 0;
1553 restore:
1554         btrfs_ctx_to_info(fs_info, &old_ctx);
1555         btrfs_remount_cleanup(fs_info, old_ctx.mount_opt);
1556         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1557         return ret;
1558 }
1559
1560 /* Used to sort the devices by max_avail(descending sort) */
1561 static int btrfs_cmp_device_free_bytes(const void *a, const void *b)
1562 {
1563         const struct btrfs_device_info *dev_info1 = a;
1564         const struct btrfs_device_info *dev_info2 = b;
1565
1566         if (dev_info1->max_avail > dev_info2->max_avail)
1567                 return -1;
1568         else if (dev_info1->max_avail < dev_info2->max_avail)
1569                 return 1;
1570         return 0;
1571 }
1572
1573 /*
1574  * sort the devices by max_avail, in which max free extent size of each device
1575  * is stored.(Descending Sort)
1576  */
1577 static inline void btrfs_descending_sort_devices(
1578                                         struct btrfs_device_info *devices,
1579                                         size_t nr_devices)
1580 {
1581         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1582              btrfs_cmp_device_free_bytes, NULL);
1583 }
1584
1585 /*
1586  * The helper to calc the free space on the devices that can be used to store
1587  * file data.
1588  */
1589 static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
1590                                               u64 *free_bytes)
1591 {
1592         struct btrfs_device_info *devices_info;
1593         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1594         struct btrfs_device *device;
1595         u64 type;
1596         u64 avail_space;
1597         u64 min_stripe_size;
1598         int num_stripes = 1;
1599         int i = 0, nr_devices;
1600         const struct btrfs_raid_attr *rattr;
1601
1602         /*
1603          * We aren't under the device list lock, so this is racy-ish, but good
1604          * enough for our purposes.
1605          */
1606         nr_devices = fs_info->fs_devices->open_devices;
1607         if (!nr_devices) {
1608                 smp_mb();
1609                 nr_devices = fs_info->fs_devices->open_devices;
1610                 ASSERT(nr_devices);
1611                 if (!nr_devices) {
1612                         *free_bytes = 0;
1613                         return 0;
1614                 }
1615         }
1616
1617         devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
1618                                GFP_KERNEL);
1619         if (!devices_info)
1620                 return -ENOMEM;
1621
1622         /* calc min stripe number for data space allocation */
1623         type = btrfs_data_alloc_profile(fs_info);
1624         rattr = &btrfs_raid_array[btrfs_bg_flags_to_raid_index(type)];
1625
1626         if (type & BTRFS_BLOCK_GROUP_RAID0)
1627                 num_stripes = nr_devices;
1628         else if (type & BTRFS_BLOCK_GROUP_RAID1_MASK)
1629                 num_stripes = rattr->ncopies;
1630         else if (type & BTRFS_BLOCK_GROUP_RAID10)
1631                 num_stripes = 4;
1632
1633         /* Adjust for more than 1 stripe per device */
1634         min_stripe_size = rattr->dev_stripes * BTRFS_STRIPE_LEN;
1635
1636         rcu_read_lock();
1637         list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
1638                 if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
1639                                                 &device->dev_state) ||
1640                     !device->bdev ||
1641                     test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
1642                         continue;
1643
1644                 if (i >= nr_devices)
1645                         break;
1646
1647                 avail_space = device->total_bytes - device->bytes_used;
1648
1649                 /* align with stripe_len */
1650                 avail_space = rounddown(avail_space, BTRFS_STRIPE_LEN);
1651
1652                 /*
1653                  * Ensure we have at least min_stripe_size on top of the
1654                  * reserved space on the device.
1655                  */
1656                 if (avail_space <= BTRFS_DEVICE_RANGE_RESERVED + min_stripe_size)
1657                         continue;
1658
1659                 avail_space -= BTRFS_DEVICE_RANGE_RESERVED;
1660
1661                 devices_info[i].dev = device;
1662                 devices_info[i].max_avail = avail_space;
1663
1664                 i++;
1665         }
1666         rcu_read_unlock();
1667
1668         nr_devices = i;
1669
1670         btrfs_descending_sort_devices(devices_info, nr_devices);
1671
1672         i = nr_devices - 1;
1673         avail_space = 0;
1674         while (nr_devices >= rattr->devs_min) {
1675                 num_stripes = min(num_stripes, nr_devices);
1676
1677                 if (devices_info[i].max_avail >= min_stripe_size) {
1678                         int j;
1679                         u64 alloc_size;
1680
1681                         avail_space += devices_info[i].max_avail * num_stripes;
1682                         alloc_size = devices_info[i].max_avail;
1683                         for (j = i + 1 - num_stripes; j <= i; j++)
1684                                 devices_info[j].max_avail -= alloc_size;
1685                 }
1686                 i--;
1687                 nr_devices--;
1688         }
1689
1690         kfree(devices_info);
1691         *free_bytes = avail_space;
1692         return 0;
1693 }
1694
1695 /*
1696  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
1697  *
1698  * If there's a redundant raid level at DATA block groups, use the respective
1699  * multiplier to scale the sizes.
1700  *
1701  * Unused device space usage is based on simulating the chunk allocator
1702  * algorithm that respects the device sizes and order of allocations.  This is
1703  * a close approximation of the actual use but there are other factors that may
1704  * change the result (like a new metadata chunk).
1705  *
1706  * If metadata is exhausted, f_bavail will be 0.
1707  */
1708 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1709 {
1710         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
1711         struct btrfs_super_block *disk_super = fs_info->super_copy;
1712         struct btrfs_space_info *found;
1713         u64 total_used = 0;
1714         u64 total_free_data = 0;
1715         u64 total_free_meta = 0;
1716         u32 bits = fs_info->sectorsize_bits;
1717         __be32 *fsid = (__be32 *)fs_info->fs_devices->fsid;
1718         unsigned factor = 1;
1719         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
1720         int ret;
1721         u64 thresh = 0;
1722         int mixed = 0;
1723
1724         list_for_each_entry(found, &fs_info->space_info, list) {
1725                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
1726                         int i;
1727
1728                         total_free_data += found->disk_total - found->disk_used;
1729                         total_free_data -=
1730                                 btrfs_account_ro_block_groups_free_space(found);
1731
1732                         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
1733                                 if (!list_empty(&found->block_groups[i]))
1734                                         factor = btrfs_bg_type_to_factor(
1735                                                 btrfs_raid_array[i].bg_flag);
1736                         }
1737                 }
1738
1739                 /*
1740                  * Metadata in mixed block group profiles are accounted in data
1741                  */
1742                 if (!mixed && found->flags & BTRFS_BLOCK_GROUP_METADATA) {
1743                         if (found->flags & BTRFS_BLOCK_GROUP_DATA)
1744                                 mixed = 1;
1745                         else
1746                                 total_free_meta += found->disk_total -
1747                                         found->disk_used;
1748                 }
1749
1750                 total_used += found->disk_used;
1751         }
1752
1753         buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
1754         buf->f_blocks >>= bits;
1755         buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
1756
1757         /* Account global block reserve as used, it's in logical size already */
1758         spin_lock(&block_rsv->lock);
1759         /* Mixed block groups accounting is not byte-accurate, avoid overflow */
1760         if (buf->f_bfree >= block_rsv->size >> bits)
1761                 buf->f_bfree -= block_rsv->size >> bits;
1762         else
1763                 buf->f_bfree = 0;
1764         spin_unlock(&block_rsv->lock);
1765
1766         buf->f_bavail = div_u64(total_free_data, factor);
1767         ret = btrfs_calc_avail_data_space(fs_info, &total_free_data);
1768         if (ret)
1769                 return ret;
1770         buf->f_bavail += div_u64(total_free_data, factor);
1771         buf->f_bavail = buf->f_bavail >> bits;
1772
1773         /*
1774          * We calculate the remaining metadata space minus global reserve. If
1775          * this is (supposedly) smaller than zero, there's no space. But this
1776          * does not hold in practice, the exhausted state happens where's still
1777          * some positive delta. So we apply some guesswork and compare the
1778          * delta to a 4M threshold.  (Practically observed delta was ~2M.)
1779          *
1780          * We probably cannot calculate the exact threshold value because this
1781          * depends on the internal reservations requested by various
1782          * operations, so some operations that consume a few metadata will
1783          * succeed even if the Avail is zero. But this is better than the other
1784          * way around.
1785          */
1786         thresh = SZ_4M;
1787
1788         /*
1789          * We only want to claim there's no available space if we can no longer
1790          * allocate chunks for our metadata profile and our global reserve will
1791          * not fit in the free metadata space.  If we aren't ->full then we
1792          * still can allocate chunks and thus are fine using the currently
1793          * calculated f_bavail.
1794          */
1795         if (!mixed && block_rsv->space_info->full &&
1796             (total_free_meta < thresh || total_free_meta - thresh < block_rsv->size))
1797                 buf->f_bavail = 0;
1798
1799         buf->f_type = BTRFS_SUPER_MAGIC;
1800         buf->f_bsize = fs_info->sectorsize;
1801         buf->f_namelen = BTRFS_NAME_LEN;
1802
1803         /* We treat it as constant endianness (it doesn't matter _which_)
1804            because we want the fsid to come out the same whether mounted
1805            on a big-endian or little-endian host */
1806         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
1807         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
1808         /* Mask in the root object ID too, to disambiguate subvols */
1809         buf->f_fsid.val[0] ^= btrfs_root_id(BTRFS_I(d_inode(dentry))->root) >> 32;
1810         buf->f_fsid.val[1] ^= btrfs_root_id(BTRFS_I(d_inode(dentry))->root);
1811
1812         return 0;
1813 }
1814
1815 static int btrfs_fc_test_super(struct super_block *sb, struct fs_context *fc)
1816 {
1817         struct btrfs_fs_info *p = fc->s_fs_info;
1818         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1819
1820         return fs_info->fs_devices == p->fs_devices;
1821 }
1822
1823 static int btrfs_get_tree_super(struct fs_context *fc)
1824 {
1825         struct btrfs_fs_info *fs_info = fc->s_fs_info;
1826         struct btrfs_fs_context *ctx = fc->fs_private;
1827         struct btrfs_fs_devices *fs_devices = NULL;
1828         struct block_device *bdev;
1829         struct btrfs_device *device;
1830         struct super_block *sb;
1831         blk_mode_t mode = btrfs_open_mode(fc);
1832         int ret;
1833
1834         btrfs_ctx_to_info(fs_info, ctx);
1835         mutex_lock(&uuid_mutex);
1836
1837         /*
1838          * With 'true' passed to btrfs_scan_one_device() (mount time) we expect
1839          * either a valid device or an error.
1840          */
1841         device = btrfs_scan_one_device(fc->source, mode, true);
1842         ASSERT(device != NULL);
1843         if (IS_ERR(device)) {
1844                 mutex_unlock(&uuid_mutex);
1845                 return PTR_ERR(device);
1846         }
1847
1848         fs_devices = device->fs_devices;
1849         fs_info->fs_devices = fs_devices;
1850
1851         ret = btrfs_open_devices(fs_devices, mode, &btrfs_fs_type);
1852         mutex_unlock(&uuid_mutex);
1853         if (ret)
1854                 return ret;
1855
1856         if (!(fc->sb_flags & SB_RDONLY) && fs_devices->rw_devices == 0) {
1857                 ret = -EACCES;
1858                 goto error;
1859         }
1860
1861         bdev = fs_devices->latest_dev->bdev;
1862
1863         /*
1864          * From now on the error handling is not straightforward.
1865          *
1866          * If successful, this will transfer the fs_info into the super block,
1867          * and fc->s_fs_info will be NULL.  However if there's an existing
1868          * super, we'll still have fc->s_fs_info populated.  If we error
1869          * completely out it'll be cleaned up when we drop the fs_context,
1870          * otherwise it's tied to the lifetime of the super_block.
1871          */
1872         sb = sget_fc(fc, btrfs_fc_test_super, set_anon_super_fc);
1873         if (IS_ERR(sb)) {
1874                 ret = PTR_ERR(sb);
1875                 goto error;
1876         }
1877
1878         set_device_specific_options(fs_info);
1879
1880         if (sb->s_root) {
1881                 btrfs_close_devices(fs_devices);
1882                 if ((fc->sb_flags ^ sb->s_flags) & SB_RDONLY)
1883                         ret = -EBUSY;
1884         } else {
1885                 snprintf(sb->s_id, sizeof(sb->s_id), "%pg", bdev);
1886                 shrinker_debugfs_rename(sb->s_shrink, "sb-btrfs:%s", sb->s_id);
1887                 btrfs_sb(sb)->bdev_holder = &btrfs_fs_type;
1888                 ret = btrfs_fill_super(sb, fs_devices, NULL);
1889         }
1890
1891         if (ret) {
1892                 deactivate_locked_super(sb);
1893                 return ret;
1894         }
1895
1896         btrfs_clear_oneshot_options(fs_info);
1897
1898         fc->root = dget(sb->s_root);
1899         return 0;
1900
1901 error:
1902         btrfs_close_devices(fs_devices);
1903         return ret;
1904 }
1905
1906 /*
1907  * Ever since commit 0723a0473fb4 ("btrfs: allow mounting btrfs subvolumes
1908  * with different ro/rw options") the following works:
1909  *
1910  *        (i) mount /dev/sda3 -o subvol=foo,ro /mnt/foo
1911  *       (ii) mount /dev/sda3 -o subvol=bar,rw /mnt/bar
1912  *
1913  * which looks nice and innocent but is actually pretty intricate and deserves
1914  * a long comment.
1915  *
1916  * On another filesystem a subvolume mount is close to something like:
1917  *
1918  *      (iii) # create rw superblock + initial mount
1919  *            mount -t xfs /dev/sdb /opt/
1920  *
1921  *            # create ro bind mount
1922  *            mount --bind -o ro /opt/foo /mnt/foo
1923  *
1924  *            # unmount initial mount
1925  *            umount /opt
1926  *
1927  * Of course, there's some special subvolume sauce and there's the fact that the
1928  * sb->s_root dentry is really swapped after mount_subtree(). But conceptually
1929  * it's very close and will help us understand the issue.
1930  *
1931  * The old mount API didn't cleanly distinguish between a mount being made ro
1932  * and a superblock being made ro.  The only way to change the ro state of
1933  * either object was by passing ms_rdonly. If a new mount was created via
1934  * mount(2) such as:
1935  *
1936  *      mount("/dev/sdb", "/mnt", "xfs", ms_rdonly, null);
1937  *
1938  * the MS_RDONLY flag being specified had two effects:
1939  *
1940  * (1) MNT_READONLY was raised -> the resulting mount got
1941  *     @mnt->mnt_flags |= MNT_READONLY raised.
1942  *
1943  * (2) MS_RDONLY was passed to the filesystem's mount method and the filesystems
1944  *     made the superblock ro. Note, how SB_RDONLY has the same value as
1945  *     ms_rdonly and is raised whenever MS_RDONLY is passed through mount(2).
1946  *
1947  * Creating a subtree mount via (iii) ends up leaving a rw superblock with a
1948  * subtree mounted ro.
1949  *
1950  * But consider the effect on the old mount API on btrfs subvolume mounting
1951  * which combines the distinct step in (iii) into a single step.
1952  *
1953  * By issuing (i) both the mount and the superblock are turned ro. Now when (ii)
1954  * is issued the superblock is ro and thus even if the mount created for (ii) is
1955  * rw it wouldn't help. Hence, btrfs needed to transition the superblock from ro
1956  * to rw for (ii) which it did using an internal remount call.
1957  *
1958  * IOW, subvolume mounting was inherently complicated due to the ambiguity of
1959  * MS_RDONLY in mount(2). Note, this ambiguity has mount(8) always translate
1960  * "ro" to MS_RDONLY. IOW, in both (i) and (ii) "ro" becomes MS_RDONLY when
1961  * passed by mount(8) to mount(2).
1962  *
1963  * Enter the new mount API. The new mount API disambiguates making a mount ro
1964  * and making a superblock ro.
1965  *
1966  * (3) To turn a mount ro the MOUNT_ATTR_ONLY flag can be used with either
1967  *     fsmount() or mount_setattr() this is a pure VFS level change for a
1968  *     specific mount or mount tree that is never seen by the filesystem itself.
1969  *
1970  * (4) To turn a superblock ro the "ro" flag must be used with
1971  *     fsconfig(FSCONFIG_SET_FLAG, "ro"). This option is seen by the filesystem
1972  *     in fc->sb_flags.
1973  *
1974  * This disambiguation has rather positive consequences.  Mounting a subvolume
1975  * ro will not also turn the superblock ro. Only the mount for the subvolume
1976  * will become ro.
1977  *
1978  * So, if the superblock creation request comes from the new mount API the
1979  * caller must have explicitly done:
1980  *
1981  *      fsconfig(FSCONFIG_SET_FLAG, "ro")
1982  *      fsmount/mount_setattr(MOUNT_ATTR_RDONLY)
1983  *
1984  * IOW, at some point the caller must have explicitly turned the whole
1985  * superblock ro and we shouldn't just undo it like we did for the old mount
1986  * API. In any case, it lets us avoid the hack in the new mount API.
1987  *
1988  * Consequently, the remounting hack must only be used for requests originating
1989  * from the old mount API and should be marked for full deprecation so it can be
1990  * turned off in a couple of years.
1991  *
1992  * The new mount API has no reason to support this hack.
1993  */
1994 static struct vfsmount *btrfs_reconfigure_for_mount(struct fs_context *fc)
1995 {
1996         struct vfsmount *mnt;
1997         int ret;
1998         const bool ro2rw = !(fc->sb_flags & SB_RDONLY);
1999
2000         /*
2001          * We got an EBUSY because our SB_RDONLY flag didn't match the existing
2002          * super block, so invert our setting here and retry the mount so we
2003          * can get our vfsmount.
2004          */
2005         if (ro2rw)
2006                 fc->sb_flags |= SB_RDONLY;
2007         else
2008                 fc->sb_flags &= ~SB_RDONLY;
2009
2010         mnt = fc_mount(fc);
2011         if (IS_ERR(mnt))
2012                 return mnt;
2013
2014         if (!fc->oldapi || !ro2rw)
2015                 return mnt;
2016
2017         /* We need to convert to rw, call reconfigure. */
2018         fc->sb_flags &= ~SB_RDONLY;
2019         down_write(&mnt->mnt_sb->s_umount);
2020         ret = btrfs_reconfigure(fc);
2021         up_write(&mnt->mnt_sb->s_umount);
2022         if (ret) {
2023                 mntput(mnt);
2024                 return ERR_PTR(ret);
2025         }
2026         return mnt;
2027 }
2028
2029 static int btrfs_get_tree_subvol(struct fs_context *fc)
2030 {
2031         struct btrfs_fs_info *fs_info = NULL;
2032         struct btrfs_fs_context *ctx = fc->fs_private;
2033         struct fs_context *dup_fc;
2034         struct dentry *dentry;
2035         struct vfsmount *mnt;
2036
2037         /*
2038          * Setup a dummy root and fs_info for test/set super.  This is because
2039          * we don't actually fill this stuff out until open_ctree, but we need
2040          * then open_ctree will properly initialize the file system specific
2041          * settings later.  btrfs_init_fs_info initializes the static elements
2042          * of the fs_info (locks and such) to make cleanup easier if we find a
2043          * superblock with our given fs_devices later on at sget() time.
2044          */
2045         fs_info = kvzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
2046         if (!fs_info)
2047                 return -ENOMEM;
2048
2049         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
2050         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
2051         if (!fs_info->super_copy || !fs_info->super_for_commit) {
2052                 btrfs_free_fs_info(fs_info);
2053                 return -ENOMEM;
2054         }
2055         btrfs_init_fs_info(fs_info);
2056
2057         dup_fc = vfs_dup_fs_context(fc);
2058         if (IS_ERR(dup_fc)) {
2059                 btrfs_free_fs_info(fs_info);
2060                 return PTR_ERR(dup_fc);
2061         }
2062
2063         /*
2064          * When we do the sget_fc this gets transferred to the sb, so we only
2065          * need to set it on the dup_fc as this is what creates the super block.
2066          */
2067         dup_fc->s_fs_info = fs_info;
2068
2069         /*
2070          * We'll do the security settings in our btrfs_get_tree_super() mount
2071          * loop, they were duplicated into dup_fc, we can drop the originals
2072          * here.
2073          */
2074         security_free_mnt_opts(&fc->security);
2075         fc->security = NULL;
2076
2077         mnt = fc_mount(dup_fc);
2078         if (PTR_ERR_OR_ZERO(mnt) == -EBUSY)
2079                 mnt = btrfs_reconfigure_for_mount(dup_fc);
2080         put_fs_context(dup_fc);
2081         if (IS_ERR(mnt))
2082                 return PTR_ERR(mnt);
2083
2084         /*
2085          * This free's ->subvol_name, because if it isn't set we have to
2086          * allocate a buffer to hold the subvol_name, so we just drop our
2087          * reference to it here.
2088          */
2089         dentry = mount_subvol(ctx->subvol_name, ctx->subvol_objectid, mnt);
2090         ctx->subvol_name = NULL;
2091         if (IS_ERR(dentry))
2092                 return PTR_ERR(dentry);
2093
2094         fc->root = dentry;
2095         return 0;
2096 }
2097
2098 static int btrfs_get_tree(struct fs_context *fc)
2099 {
2100         /*
2101          * Since we use mount_subtree to mount the default/specified subvol, we
2102          * have to do mounts in two steps.
2103          *
2104          * First pass through we call btrfs_get_tree_subvol(), this is just a
2105          * wrapper around fc_mount() to call back into here again, and this time
2106          * we'll call btrfs_get_tree_super().  This will do the open_ctree() and
2107          * everything to open the devices and file system.  Then we return back
2108          * with a fully constructed vfsmount in btrfs_get_tree_subvol(), and
2109          * from there we can do our mount_subvol() call, which will lookup
2110          * whichever subvol we're mounting and setup this fc with the
2111          * appropriate dentry for the subvol.
2112          */
2113         if (fc->s_fs_info)
2114                 return btrfs_get_tree_super(fc);
2115         return btrfs_get_tree_subvol(fc);
2116 }
2117
2118 static void btrfs_kill_super(struct super_block *sb)
2119 {
2120         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2121         kill_anon_super(sb);
2122         btrfs_free_fs_info(fs_info);
2123 }
2124
2125 static void btrfs_free_fs_context(struct fs_context *fc)
2126 {
2127         struct btrfs_fs_context *ctx = fc->fs_private;
2128         struct btrfs_fs_info *fs_info = fc->s_fs_info;
2129
2130         if (fs_info)
2131                 btrfs_free_fs_info(fs_info);
2132
2133         if (ctx && refcount_dec_and_test(&ctx->refs)) {
2134                 kfree(ctx->subvol_name);
2135                 kfree(ctx);
2136         }
2137 }
2138
2139 static int btrfs_dup_fs_context(struct fs_context *fc, struct fs_context *src_fc)
2140 {
2141         struct btrfs_fs_context *ctx = src_fc->fs_private;
2142
2143         /*
2144          * Give a ref to our ctx to this dup, as we want to keep it around for
2145          * our original fc so we can have the subvolume name or objectid.
2146          *
2147          * We unset ->source in the original fc because the dup needs it for
2148          * mounting, and then once we free the dup it'll free ->source, so we
2149          * need to make sure we're only pointing to it in one fc.
2150          */
2151         refcount_inc(&ctx->refs);
2152         fc->fs_private = ctx;
2153         fc->source = src_fc->source;
2154         src_fc->source = NULL;
2155         return 0;
2156 }
2157
2158 static const struct fs_context_operations btrfs_fs_context_ops = {
2159         .parse_param    = btrfs_parse_param,
2160         .reconfigure    = btrfs_reconfigure,
2161         .get_tree       = btrfs_get_tree,
2162         .dup            = btrfs_dup_fs_context,
2163         .free           = btrfs_free_fs_context,
2164 };
2165
2166 static int btrfs_init_fs_context(struct fs_context *fc)
2167 {
2168         struct btrfs_fs_context *ctx;
2169
2170         ctx = kzalloc(sizeof(struct btrfs_fs_context), GFP_KERNEL);
2171         if (!ctx)
2172                 return -ENOMEM;
2173
2174         refcount_set(&ctx->refs, 1);
2175         fc->fs_private = ctx;
2176         fc->ops = &btrfs_fs_context_ops;
2177
2178         if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
2179                 btrfs_info_to_ctx(btrfs_sb(fc->root->d_sb), ctx);
2180         } else {
2181                 ctx->thread_pool_size =
2182                         min_t(unsigned long, num_online_cpus() + 2, 8);
2183                 ctx->max_inline = BTRFS_DEFAULT_MAX_INLINE;
2184                 ctx->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
2185         }
2186
2187 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
2188         fc->sb_flags |= SB_POSIXACL;
2189 #endif
2190         fc->sb_flags |= SB_I_VERSION;
2191
2192         return 0;
2193 }
2194
2195 static struct file_system_type btrfs_fs_type = {
2196         .owner                  = THIS_MODULE,
2197         .name                   = "btrfs",
2198         .init_fs_context        = btrfs_init_fs_context,
2199         .parameters             = btrfs_fs_parameters,
2200         .kill_sb                = btrfs_kill_super,
2201         .fs_flags               = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA | FS_ALLOW_IDMAP,
2202  };
2203
2204 MODULE_ALIAS_FS("btrfs");
2205
2206 static int btrfs_control_open(struct inode *inode, struct file *file)
2207 {
2208         /*
2209          * The control file's private_data is used to hold the
2210          * transaction when it is started and is used to keep
2211          * track of whether a transaction is already in progress.
2212          */
2213         file->private_data = NULL;
2214         return 0;
2215 }
2216
2217 /*
2218  * Used by /dev/btrfs-control for devices ioctls.
2219  */
2220 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
2221                                 unsigned long arg)
2222 {
2223         struct btrfs_ioctl_vol_args *vol;
2224         struct btrfs_device *device = NULL;
2225         dev_t devt = 0;
2226         int ret = -ENOTTY;
2227
2228         if (!capable(CAP_SYS_ADMIN))
2229                 return -EPERM;
2230
2231         vol = memdup_user((void __user *)arg, sizeof(*vol));
2232         if (IS_ERR(vol))
2233                 return PTR_ERR(vol);
2234         ret = btrfs_check_ioctl_vol_args_path(vol);
2235         if (ret < 0)
2236                 goto out;
2237
2238         switch (cmd) {
2239         case BTRFS_IOC_SCAN_DEV:
2240                 mutex_lock(&uuid_mutex);
2241                 /*
2242                  * Scanning outside of mount can return NULL which would turn
2243                  * into 0 error code.
2244                  */
2245                 device = btrfs_scan_one_device(vol->name, BLK_OPEN_READ, false);
2246                 ret = PTR_ERR_OR_ZERO(device);
2247                 mutex_unlock(&uuid_mutex);
2248                 break;
2249         case BTRFS_IOC_FORGET_DEV:
2250                 if (vol->name[0] != 0) {
2251                         ret = lookup_bdev(vol->name, &devt);
2252                         if (ret)
2253                                 break;
2254                 }
2255                 ret = btrfs_forget_devices(devt);
2256                 break;
2257         case BTRFS_IOC_DEVICES_READY:
2258                 mutex_lock(&uuid_mutex);
2259                 /*
2260                  * Scanning outside of mount can return NULL which would turn
2261                  * into 0 error code.
2262                  */
2263                 device = btrfs_scan_one_device(vol->name, BLK_OPEN_READ, false);
2264                 if (IS_ERR_OR_NULL(device)) {
2265                         mutex_unlock(&uuid_mutex);
2266                         ret = PTR_ERR(device);
2267                         break;
2268                 }
2269                 ret = !(device->fs_devices->num_devices ==
2270                         device->fs_devices->total_devices);
2271                 mutex_unlock(&uuid_mutex);
2272                 break;
2273         case BTRFS_IOC_GET_SUPPORTED_FEATURES:
2274                 ret = btrfs_ioctl_get_supported_features((void __user*)arg);
2275                 break;
2276         }
2277
2278 out:
2279         kfree(vol);
2280         return ret;
2281 }
2282
2283 static int btrfs_freeze(struct super_block *sb)
2284 {
2285         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2286
2287         set_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2288         /*
2289          * We don't need a barrier here, we'll wait for any transaction that
2290          * could be in progress on other threads (and do delayed iputs that
2291          * we want to avoid on a frozen filesystem), or do the commit
2292          * ourselves.
2293          */
2294         return btrfs_commit_current_transaction(fs_info->tree_root);
2295 }
2296
2297 static int check_dev_super(struct btrfs_device *dev)
2298 {
2299         struct btrfs_fs_info *fs_info = dev->fs_info;
2300         struct btrfs_super_block *sb;
2301         u64 last_trans;
2302         u16 csum_type;
2303         int ret = 0;
2304
2305         /* This should be called with fs still frozen. */
2306         ASSERT(test_bit(BTRFS_FS_FROZEN, &fs_info->flags));
2307
2308         /* Missing dev, no need to check. */
2309         if (!dev->bdev)
2310                 return 0;
2311
2312         /* Only need to check the primary super block. */
2313         sb = btrfs_read_dev_one_super(dev->bdev, 0, true);
2314         if (IS_ERR(sb))
2315                 return PTR_ERR(sb);
2316
2317         /* Verify the checksum. */
2318         csum_type = btrfs_super_csum_type(sb);
2319         if (csum_type != btrfs_super_csum_type(fs_info->super_copy)) {
2320                 btrfs_err(fs_info, "csum type changed, has %u expect %u",
2321                           csum_type, btrfs_super_csum_type(fs_info->super_copy));
2322                 ret = -EUCLEAN;
2323                 goto out;
2324         }
2325
2326         if (btrfs_check_super_csum(fs_info, sb)) {
2327                 btrfs_err(fs_info, "csum for on-disk super block no longer matches");
2328                 ret = -EUCLEAN;
2329                 goto out;
2330         }
2331
2332         /* Btrfs_validate_super() includes fsid check against super->fsid. */
2333         ret = btrfs_validate_super(fs_info, sb, 0);
2334         if (ret < 0)
2335                 goto out;
2336
2337         last_trans = btrfs_get_last_trans_committed(fs_info);
2338         if (btrfs_super_generation(sb) != last_trans) {
2339                 btrfs_err(fs_info, "transid mismatch, has %llu expect %llu",
2340                           btrfs_super_generation(sb), last_trans);
2341                 ret = -EUCLEAN;
2342                 goto out;
2343         }
2344 out:
2345         btrfs_release_disk_super(sb);
2346         return ret;
2347 }
2348
2349 static int btrfs_unfreeze(struct super_block *sb)
2350 {
2351         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2352         struct btrfs_device *device;
2353         int ret = 0;
2354
2355         /*
2356          * Make sure the fs is not changed by accident (like hibernation then
2357          * modified by other OS).
2358          * If we found anything wrong, we mark the fs error immediately.
2359          *
2360          * And since the fs is frozen, no one can modify the fs yet, thus
2361          * we don't need to hold device_list_mutex.
2362          */
2363         list_for_each_entry(device, &fs_info->fs_devices->devices, dev_list) {
2364                 ret = check_dev_super(device);
2365                 if (ret < 0) {
2366                         btrfs_handle_fs_error(fs_info, ret,
2367                                 "super block on devid %llu got modified unexpectedly",
2368                                 device->devid);
2369                         break;
2370                 }
2371         }
2372         clear_bit(BTRFS_FS_FROZEN, &fs_info->flags);
2373
2374         /*
2375          * We still return 0, to allow VFS layer to unfreeze the fs even the
2376          * above checks failed. Since the fs is either fine or read-only, we're
2377          * safe to continue, without causing further damage.
2378          */
2379         return 0;
2380 }
2381
2382 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
2383 {
2384         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
2385
2386         /*
2387          * There should be always a valid pointer in latest_dev, it may be stale
2388          * for a short moment in case it's being deleted but still valid until
2389          * the end of RCU grace period.
2390          */
2391         rcu_read_lock();
2392         seq_escape(m, btrfs_dev_name(fs_info->fs_devices->latest_dev), " \t\n\\");
2393         rcu_read_unlock();
2394
2395         return 0;
2396 }
2397
2398 static long btrfs_nr_cached_objects(struct super_block *sb, struct shrink_control *sc)
2399 {
2400         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2401         const s64 nr = percpu_counter_sum_positive(&fs_info->evictable_extent_maps);
2402
2403         trace_btrfs_extent_map_shrinker_count(fs_info, nr);
2404
2405         /*
2406          * Only report the real number for DEBUG builds, as there are reports of
2407          * serious performance degradation caused by too frequent shrinks.
2408          */
2409         if (IS_ENABLED(CONFIG_BTRFS_DEBUG))
2410                 return nr;
2411         return 0;
2412 }
2413
2414 static long btrfs_free_cached_objects(struct super_block *sb, struct shrink_control *sc)
2415 {
2416         const long nr_to_scan = min_t(unsigned long, LONG_MAX, sc->nr_to_scan);
2417         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2418
2419         /*
2420          * We may be called from any task trying to allocate memory and we don't
2421          * want to slow it down with scanning and dropping extent maps. It would
2422          * also cause heavy lock contention if many tasks concurrently enter
2423          * here. Therefore only allow kswapd tasks to scan and drop extent maps.
2424          */
2425         if (!current_is_kswapd())
2426                 return 0;
2427
2428         return btrfs_free_extent_maps(fs_info, nr_to_scan);
2429 }
2430
2431 static const struct super_operations btrfs_super_ops = {
2432         .drop_inode     = btrfs_drop_inode,
2433         .evict_inode    = btrfs_evict_inode,
2434         .put_super      = btrfs_put_super,
2435         .sync_fs        = btrfs_sync_fs,
2436         .show_options   = btrfs_show_options,
2437         .show_devname   = btrfs_show_devname,
2438         .alloc_inode    = btrfs_alloc_inode,
2439         .destroy_inode  = btrfs_destroy_inode,
2440         .free_inode     = btrfs_free_inode,
2441         .statfs         = btrfs_statfs,
2442         .freeze_fs      = btrfs_freeze,
2443         .unfreeze_fs    = btrfs_unfreeze,
2444         .nr_cached_objects = btrfs_nr_cached_objects,
2445         .free_cached_objects = btrfs_free_cached_objects,
2446 };
2447
2448 static const struct file_operations btrfs_ctl_fops = {
2449         .open = btrfs_control_open,
2450         .unlocked_ioctl  = btrfs_control_ioctl,
2451         .compat_ioctl = compat_ptr_ioctl,
2452         .owner   = THIS_MODULE,
2453         .llseek = noop_llseek,
2454 };
2455
2456 static struct miscdevice btrfs_misc = {
2457         .minor          = BTRFS_MINOR,
2458         .name           = "btrfs-control",
2459         .fops           = &btrfs_ctl_fops
2460 };
2461
2462 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2463 MODULE_ALIAS("devname:btrfs-control");
2464
2465 static int __init btrfs_interface_init(void)
2466 {
2467         return misc_register(&btrfs_misc);
2468 }
2469
2470 static __cold void btrfs_interface_exit(void)
2471 {
2472         misc_deregister(&btrfs_misc);
2473 }
2474
2475 static int __init btrfs_print_mod_info(void)
2476 {
2477         static const char options[] = ""
2478 #ifdef CONFIG_BTRFS_DEBUG
2479                         ", debug=on"
2480 #endif
2481 #ifdef CONFIG_BTRFS_ASSERT
2482                         ", assert=on"
2483 #endif
2484 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
2485                         ", ref-verify=on"
2486 #endif
2487 #ifdef CONFIG_BLK_DEV_ZONED
2488                         ", zoned=yes"
2489 #else
2490                         ", zoned=no"
2491 #endif
2492 #ifdef CONFIG_FS_VERITY
2493                         ", fsverity=yes"
2494 #else
2495                         ", fsverity=no"
2496 #endif
2497                         ;
2498         pr_info("Btrfs loaded%s\n", options);
2499         return 0;
2500 }
2501
2502 static int register_btrfs(void)
2503 {
2504         return register_filesystem(&btrfs_fs_type);
2505 }
2506
2507 static void unregister_btrfs(void)
2508 {
2509         unregister_filesystem(&btrfs_fs_type);
2510 }
2511
2512 /* Helper structure for long init/exit functions. */
2513 struct init_sequence {
2514         int (*init_func)(void);
2515         /* Can be NULL if the init_func doesn't need cleanup. */
2516         void (*exit_func)(void);
2517 };
2518
2519 static const struct init_sequence mod_init_seq[] = {
2520         {
2521                 .init_func = btrfs_props_init,
2522                 .exit_func = NULL,
2523         }, {
2524                 .init_func = btrfs_init_sysfs,
2525                 .exit_func = btrfs_exit_sysfs,
2526         }, {
2527                 .init_func = btrfs_init_compress,
2528                 .exit_func = btrfs_exit_compress,
2529         }, {
2530                 .init_func = btrfs_init_cachep,
2531                 .exit_func = btrfs_destroy_cachep,
2532         }, {
2533                 .init_func = btrfs_init_dio,
2534                 .exit_func = btrfs_destroy_dio,
2535         }, {
2536                 .init_func = btrfs_transaction_init,
2537                 .exit_func = btrfs_transaction_exit,
2538         }, {
2539                 .init_func = btrfs_ctree_init,
2540                 .exit_func = btrfs_ctree_exit,
2541         }, {
2542                 .init_func = btrfs_free_space_init,
2543                 .exit_func = btrfs_free_space_exit,
2544         }, {
2545                 .init_func = extent_state_init_cachep,
2546                 .exit_func = extent_state_free_cachep,
2547         }, {
2548                 .init_func = extent_buffer_init_cachep,
2549                 .exit_func = extent_buffer_free_cachep,
2550         }, {
2551                 .init_func = btrfs_bioset_init,
2552                 .exit_func = btrfs_bioset_exit,
2553         }, {
2554                 .init_func = extent_map_init,
2555                 .exit_func = extent_map_exit,
2556         }, {
2557                 .init_func = ordered_data_init,
2558                 .exit_func = ordered_data_exit,
2559         }, {
2560                 .init_func = btrfs_delayed_inode_init,
2561                 .exit_func = btrfs_delayed_inode_exit,
2562         }, {
2563                 .init_func = btrfs_auto_defrag_init,
2564                 .exit_func = btrfs_auto_defrag_exit,
2565         }, {
2566                 .init_func = btrfs_delayed_ref_init,
2567                 .exit_func = btrfs_delayed_ref_exit,
2568         }, {
2569                 .init_func = btrfs_prelim_ref_init,
2570                 .exit_func = btrfs_prelim_ref_exit,
2571         }, {
2572                 .init_func = btrfs_interface_init,
2573                 .exit_func = btrfs_interface_exit,
2574         }, {
2575                 .init_func = btrfs_print_mod_info,
2576                 .exit_func = NULL,
2577         }, {
2578                 .init_func = btrfs_run_sanity_tests,
2579                 .exit_func = NULL,
2580         }, {
2581                 .init_func = register_btrfs,
2582                 .exit_func = unregister_btrfs,
2583         }
2584 };
2585
2586 static bool mod_init_result[ARRAY_SIZE(mod_init_seq)];
2587
2588 static __always_inline void btrfs_exit_btrfs_fs(void)
2589 {
2590         int i;
2591
2592         for (i = ARRAY_SIZE(mod_init_seq) - 1; i >= 0; i--) {
2593                 if (!mod_init_result[i])
2594                         continue;
2595                 if (mod_init_seq[i].exit_func)
2596                         mod_init_seq[i].exit_func();
2597                 mod_init_result[i] = false;
2598         }
2599 }
2600
2601 static void __exit exit_btrfs_fs(void)
2602 {
2603         btrfs_exit_btrfs_fs();
2604         btrfs_cleanup_fs_uuids();
2605 }
2606
2607 static int __init init_btrfs_fs(void)
2608 {
2609         int ret;
2610         int i;
2611
2612         for (i = 0; i < ARRAY_SIZE(mod_init_seq); i++) {
2613                 ASSERT(!mod_init_result[i]);
2614                 ret = mod_init_seq[i].init_func();
2615                 if (ret < 0) {
2616                         btrfs_exit_btrfs_fs();
2617                         return ret;
2618                 }
2619                 mod_init_result[i] = true;
2620         }
2621         return 0;
2622 }
2623
2624 late_initcall(init_btrfs_fs);
2625 module_exit(exit_btrfs_fs)
2626
2627 MODULE_DESCRIPTION("B-Tree File System (BTRFS)");
2628 MODULE_LICENSE("GPL");
2629 MODULE_SOFTDEP("pre: crc32c");
2630 MODULE_SOFTDEP("pre: xxhash64");
2631 MODULE_SOFTDEP("pre: sha256");
2632 MODULE_SOFTDEP("pre: blake2b-256");