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