fs/btrfs/super.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/module.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/fs.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/highmem.h>
  25 #include <linux/time.h>
  26 #include <linux/init.h>
  27 #include <linux/seq_file.h>
  28 #include <linux/string.h>
  29 #include <linux/backing-dev.h>
  30 #include <linux/mount.h>
  31 #include <linux/mpage.h>
  32 #include <linux/swap.h>
  33 #include <linux/writeback.h>
  34 #include <linux/statfs.h>
  35 #include <linux/compat.h>
  36 #include <linux/parser.h>
  37 #include <linux/ctype.h>
  38 #include <linux/namei.h>
  39 #include <linux/miscdevice.h>
  40 #include <linux/magic.h>
  41 #include <linux/slab.h>
  42 #include <linux/cleancache.h>
  43 #include <linux/ratelimit.h>
  44 #include <linux/btrfs.h>
  45 #include "delayed-inode.h"
  46 #include "ctree.h"
  47 #include "disk-io.h"
  48 #include "transaction.h"
  49 #include "btrfs_inode.h"
  50 #include "print-tree.h"
  51 #include "hash.h"
  52 #include "props.h"
  53 #include "xattr.h"
  54 #include "volumes.h"
  55 #include "export.h"
  56 #include "compression.h"
  57 #include "rcu-string.h"
  58 #include "dev-replace.h"
  59 #include "free-space-cache.h"
  60 #include "backref.h"
  61 #include "tests/btrfs-tests.h"
  62
  63 #include "qgroup.h"
  64 #define CREATE_TRACE_POINTS
  65 #include <trace/events/btrfs.h>
  66
  67 static const struct super_operations btrfs_super_ops;
  68 static struct file_system_type btrfs_fs_type;
  69
  70 static int btrfs_remount(struct super_block *sb, int *flags, char *data);
  71
  72 const char *btrfs_decode_error(int errno)
  73 {
  74         char *errstr = "unknown";
  75
  76         switch (errno) {
  77         case -EIO:
  78                 errstr = "IO failure";
  79                 break;
  80         case -ENOMEM:
  81                 errstr = "Out of memory";
  82                 break;
  83         case -EROFS:
  84                 errstr = "Readonly filesystem";
  85                 break;
  86         case -EEXIST:
  87                 errstr = "Object already exists";
  88                 break;
  89         case -ENOSPC:
  90                 errstr = "No space left";
  91                 break;
  92         case -ENOENT:
  93                 errstr = "No such entry";
  94                 break;
  95         }
  96
  97         return errstr;
  98 }
  99
 100 static void save_error_info(struct btrfs_fs_info *fs_info)
 101 {
 102         /*
 103          * today we only save the error info into ram.  Long term we'll
 104          * also send it down to the disk
 105          */
 106         set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
 107 }
 108
 109 /* btrfs handle error by forcing the filesystem readonly */
 110 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
 111 {
 112         struct super_block *sb = fs_info->sb;
 113
 114         if (sb->s_flags & MS_RDONLY)
 115                 return;
 116
 117         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 118                 sb->s_flags |= MS_RDONLY;
 119                 btrfs_info(fs_info, "forced readonly");
 120                 /*
 121                  * Note that a running device replace operation is not
 122                  * canceled here although there is no way to update
 123                  * the progress. It would add the risk of a deadlock,
 124                  * therefore the canceling is ommited. The only penalty
 125                  * is that some I/O remains active until the procedure
 126                  * completes. The next time when the filesystem is
 127                  * mounted writeable again, the device replace
 128                  * operation continues.
 129                  */
 130         }
 131 }
 132
 133 /*
 134  * __btrfs_std_error decodes expected errors from the caller and
 135  * invokes the approciate error response.
 136  */
 137 __cold
 138 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
 139                        unsigned int line, int errno, const char *fmt, ...)
 140 {
 141         struct super_block *sb = fs_info->sb;
 142 #ifdef CONFIG_PRINTK
 143         const char *errstr;
 144 #endif
 145
 146         /*
 147          * Special case: if the error is EROFS, and we're already
 148          * under MS_RDONLY, then it is safe here.
 149          */
 150         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 151                 return;
 152
 153 #ifdef CONFIG_PRINTK
 154         errstr = btrfs_decode_error(errno);
 155         if (fmt) {
 156                 struct va_format vaf;
 157                 va_list args;
 158
 159                 va_start(args, fmt);
 160                 vaf.fmt = fmt;
 161                 vaf.va = &args;
 162
 163                 printk(KERN_CRIT
 164                         "BTRFS: error (device %s) in %s:%d: errno=%d %s (%pV)\n",
 165                         sb->s_id, function, line, errno, errstr, &vaf);
 166                 va_end(args);
 167         } else {
 168                 printk(KERN_CRIT "BTRFS: error (device %s) in %s:%d: errno=%d %s\n",
 169                         sb->s_id, function, line, errno, errstr);
 170         }
 171 #endif
 172
 173         /* Don't go through full error handling during mount */
 174         save_error_info(fs_info);
 175         if (sb->s_flags & MS_BORN)
 176                 btrfs_handle_error(fs_info);
 177 }
 178
 179 #ifdef CONFIG_PRINTK
 180 static const char * const logtypes[] = {
 181         "emergency",
 182         "alert",
 183         "critical",
 184         "error",
 185         "warning",
 186         "notice",
 187         "info",
 188         "debug",
 189 };
 190
 191 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 192 {
 193         struct super_block *sb = fs_info->sb;
 194         char lvl[4];
 195         struct va_format vaf;
 196         va_list args;
 197         const char *type = logtypes[4];
 198         int kern_level;
 199
 200         va_start(args, fmt);
 201
 202         kern_level = printk_get_level(fmt);
 203         if (kern_level) {
 204                 size_t size = printk_skip_level(fmt) - fmt;
 205                 memcpy(lvl, fmt,  size);
 206                 lvl[size] = '\0';
 207                 fmt += size;
 208                 type = logtypes[kern_level - '0'];
 209         } else
 210                 *lvl = '\0';
 211
 212         vaf.fmt = fmt;
 213         vaf.va = &args;
 214
 215         printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
 216
 217         va_end(args);
 218 }
 219 #endif
 220
 221 /*
 222  * We only mark the transaction aborted and then set the file system read-only.
 223  * This will prevent new transactions from starting or trying to join this
 224  * one.
 225  *
 226  * This means that error recovery at the call site is limited to freeing
 227  * any local memory allocations and passing the error code up without
 228  * further cleanup. The transaction should complete as it normally would
 229  * in the call path but will return -EIO.
 230  *
 231  * We'll complete the cleanup in btrfs_end_transaction and
 232  * btrfs_commit_transaction.
 233  */
 234 __cold
 235 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 236                                struct btrfs_root *root, const char *function,
 237                                unsigned int line, int errno)
 238 {
 239         trans->aborted = errno;
 240         /* Nothing used. The other threads that have joined this
 241          * transaction may be able to continue. */
 242         if (!trans->blocks_used && list_empty(&trans->new_bgs)) {
 243                 const char *errstr;
 244
 245                 errstr = btrfs_decode_error(errno);
 246                 btrfs_warn(root->fs_info,
 247                            "%s:%d: Aborting unused transaction(%s).",
 248                            function, line, errstr);
 249                 return;
 250         }
 251         ACCESS_ONCE(trans->transaction->aborted) = errno;
 252         /* Wake up anybody who may be waiting on this transaction */
 253         wake_up(&root->fs_info->transaction_wait);
 254         wake_up(&root->fs_info->transaction_blocked_wait);
 255         __btrfs_std_error(root->fs_info, function, line, errno, NULL);
 256 }
 257 /*
 258  * __btrfs_panic decodes unexpected, fatal errors from the caller,
 259  * issues an alert, and either panics or BUGs, depending on mount options.
 260  */
 261 __cold
 262 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 263                    unsigned int line, int errno, const char *fmt, ...)
 264 {
 265         char *s_id = "<unknown>";
 266         const char *errstr;
 267         struct va_format vaf = { .fmt = fmt };
 268         va_list args;
 269
 270         if (fs_info)
 271                 s_id = fs_info->sb->s_id;
 272
 273         va_start(args, fmt);
 274         vaf.va = &args;
 275
 276         errstr = btrfs_decode_error(errno);
 277         if (fs_info && (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR))
 278                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
 279                         s_id, function, line, &vaf, errno, errstr);
 280
 281         btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
 282                    function, line, &vaf, errno, errstr);
 283         va_end(args);
 284         /* Caller calls BUG() */
 285 }
 286
 287 static void btrfs_put_super(struct super_block *sb)
 288 {
 289         close_ctree(btrfs_sb(sb)->tree_root);
 290 }
 291
 292 enum {
 293         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 294         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 295         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 296         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 297         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 298         Opt_space_cache, Opt_space_cache_version, Opt_clear_cache,
 299         Opt_user_subvol_rm_allowed, Opt_enospc_debug, Opt_subvolrootid,
 300         Opt_defrag, Opt_inode_cache, Opt_no_space_cache, Opt_recovery,
 301         Opt_skip_balance, Opt_check_integrity,
 302         Opt_check_integrity_including_extent_data,
 303         Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
 304         Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
 305         Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
 306         Opt_datasum, Opt_treelog, Opt_noinode_cache,
 307 #ifdef CONFIG_BTRFS_DEBUG
 308         Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 309 #endif
 310         Opt_err,
 311 };
 312
 313 static const match_table_t tokens = {
 314         {Opt_degraded, "degraded"},
 315         {Opt_subvol, "subvol=%s"},
 316         {Opt_subvolid, "subvolid=%s"},
 317         {Opt_device, "device=%s"},
 318         {Opt_nodatasum, "nodatasum"},
 319         {Opt_datasum, "datasum"},
 320         {Opt_nodatacow, "nodatacow"},
 321         {Opt_datacow, "datacow"},
 322         {Opt_nobarrier, "nobarrier"},
 323         {Opt_barrier, "barrier"},
 324         {Opt_max_inline, "max_inline=%s"},
 325         {Opt_alloc_start, "alloc_start=%s"},
 326         {Opt_thread_pool, "thread_pool=%d"},
 327         {Opt_compress, "compress"},
 328         {Opt_compress_type, "compress=%s"},
 329         {Opt_compress_force, "compress-force"},
 330         {Opt_compress_force_type, "compress-force=%s"},
 331         {Opt_ssd, "ssd"},
 332         {Opt_ssd_spread, "ssd_spread"},
 333         {Opt_nossd, "nossd"},
 334         {Opt_acl, "acl"},
 335         {Opt_noacl, "noacl"},
 336         {Opt_notreelog, "notreelog"},
 337         {Opt_treelog, "treelog"},
 338         {Opt_flushoncommit, "flushoncommit"},
 339         {Opt_noflushoncommit, "noflushoncommit"},
 340         {Opt_ratio, "metadata_ratio=%d"},
 341         {Opt_discard, "discard"},
 342         {Opt_nodiscard, "nodiscard"},
 343         {Opt_space_cache, "space_cache"},
 344         {Opt_space_cache_version, "space_cache=%s"},
 345         {Opt_clear_cache, "clear_cache"},
 346         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 347         {Opt_enospc_debug, "enospc_debug"},
 348         {Opt_noenospc_debug, "noenospc_debug"},
 349         {Opt_subvolrootid, "subvolrootid=%d"},
 350         {Opt_defrag, "autodefrag"},
 351         {Opt_nodefrag, "noautodefrag"},
 352         {Opt_inode_cache, "inode_cache"},
 353         {Opt_noinode_cache, "noinode_cache"},
 354         {Opt_no_space_cache, "nospace_cache"},
 355         {Opt_recovery, "recovery"},
 356         {Opt_skip_balance, "skip_balance"},
 357         {Opt_check_integrity, "check_int"},
 358         {Opt_check_integrity_including_extent_data, "check_int_data"},
 359         {Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
 360         {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
 361         {Opt_fatal_errors, "fatal_errors=%s"},
 362         {Opt_commit_interval, "commit=%d"},
 363 #ifdef CONFIG_BTRFS_DEBUG
 364         {Opt_fragment_data, "fragment=data"},
 365         {Opt_fragment_metadata, "fragment=metadata"},
 366         {Opt_fragment_all, "fragment=all"},
 367 #endif
 368         {Opt_err, NULL},
 369 };
 370
 371 /*
 372  * Regular mount options parser.  Everything that is needed only when
 373  * reading in a new superblock is parsed here.
 374  * XXX JDM: This needs to be cleaned up for remount.
 375  */
 376 int btrfs_parse_options(struct btrfs_root *root, char *options)
 377 {
 378         struct btrfs_fs_info *info = root->fs_info;
 379         substring_t args[MAX_OPT_ARGS];
 380         char *p, *num, *orig = NULL;
 381         u64 cache_gen;
 382         int intarg;
 383         int ret = 0;
 384         char *compress_type;
 385         bool compress_force = false;
 386         enum btrfs_compression_type saved_compress_type;
 387         bool saved_compress_force;
 388         int no_compress = 0;
 389
 390         cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
 391         if (btrfs_fs_compat_ro(root->fs_info, FREE_SPACE_TREE))
 392                 btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
 393         else if (cache_gen)
 394                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 395
 396         if (!options)
 397                 goto out;
 398
 399         /*
 400          * strsep changes the string, duplicate it because parse_options
 401          * gets called twice
 402          */
 403         options = kstrdup(options, GFP_NOFS);
 404         if (!options)
 405                 return -ENOMEM;
 406
 407         orig = options;
 408
 409         while ((p = strsep(&options, ",")) != NULL) {
 410                 int token;
 411                 if (!*p)
 412                         continue;
 413
 414                 token = match_token(p, tokens, args);
 415                 switch (token) {
 416                 case Opt_degraded:
 417                         btrfs_info(root->fs_info, "allowing degraded mounts");
 418                         btrfs_set_opt(info->mount_opt, DEGRADED);
 419                         break;
 420                 case Opt_subvol:
 421                 case Opt_subvolid:
 422                 case Opt_subvolrootid:
 423                 case Opt_device:
 424                         /*
 425                          * These are parsed by btrfs_parse_early_options
 426                          * and can be happily ignored here.
 427                          */
 428                         break;
 429                 case Opt_nodatasum:
 430                         btrfs_set_and_info(root, NODATASUM,
 431                                            "setting nodatasum");
 432                         break;
 433                 case Opt_datasum:
 434                         if (btrfs_test_opt(root, NODATASUM)) {
 435                                 if (btrfs_test_opt(root, NODATACOW))
 436                                         btrfs_info(root->fs_info, "setting datasum, datacow enabled");
 437                                 else
 438                                         btrfs_info(root->fs_info, "setting datasum");
 439                         }
 440                         btrfs_clear_opt(info->mount_opt, NODATACOW);
 441                         btrfs_clear_opt(info->mount_opt, NODATASUM);
 442                         break;
 443                 case Opt_nodatacow:
 444                         if (!btrfs_test_opt(root, NODATACOW)) {
 445                                 if (!btrfs_test_opt(root, COMPRESS) ||
 446                                     !btrfs_test_opt(root, FORCE_COMPRESS)) {
 447                                         btrfs_info(root->fs_info,
 448                                                    "setting nodatacow, compression disabled");
 449                                 } else {
 450                                         btrfs_info(root->fs_info, "setting nodatacow");
 451                                 }
 452                         }
 453                         btrfs_clear_opt(info->mount_opt, COMPRESS);
 454                         btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 455                         btrfs_set_opt(info->mount_opt, NODATACOW);
 456                         btrfs_set_opt(info->mount_opt, NODATASUM);
 457                         break;
 458                 case Opt_datacow:
 459                         btrfs_clear_and_info(root, NODATACOW,
 460                                              "setting datacow");
 461                         break;
 462                 case Opt_compress_force:
 463                 case Opt_compress_force_type:
 464                         compress_force = true;
 465                         /* Fallthrough */
 466                 case Opt_compress:
 467                 case Opt_compress_type:
 468                         saved_compress_type = btrfs_test_opt(root, COMPRESS) ?
 469                                 info->compress_type : BTRFS_COMPRESS_NONE;
 470                         saved_compress_force =
 471                                 btrfs_test_opt(root, FORCE_COMPRESS);
 472                         if (token == Opt_compress ||
 473                             token == Opt_compress_force ||
 474                             strcmp(args[0].from, "zlib") == 0) {
 475                                 compress_type = "zlib";
 476                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 477                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 478                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 479                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 480                                 no_compress = 0;
 481                         } else if (strcmp(args[0].from, "lzo") == 0) {
 482                                 compress_type = "lzo";
 483                                 info->compress_type = BTRFS_COMPRESS_LZO;
 484                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 485                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
 486                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
 487                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
 488                                 no_compress = 0;
 489                         } else if (strncmp(args[0].from, "no", 2) == 0) {
 490                                 compress_type = "no";
 491                                 btrfs_clear_opt(info->mount_opt, COMPRESS);
 492                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 493                                 compress_force = false;
 494                                 no_compress++;
 495                         } else {
 496                                 ret = -EINVAL;
 497                                 goto out;
 498                         }
 499
 500                         if (compress_force) {
 501                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 502                         } else {
 503                                 /*
 504                                  * If we remount from compress-force=xxx to
 505                                  * compress=xxx, we need clear FORCE_COMPRESS
 506                                  * flag, otherwise, there is no way for users
 507                                  * to disable forcible compression separately.
 508                                  */
 509                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 510                         }
 511                         if ((btrfs_test_opt(root, COMPRESS) &&
 512                              (info->compress_type != saved_compress_type ||
 513                               compress_force != saved_compress_force)) ||
 514                             (!btrfs_test_opt(root, COMPRESS) &&
 515                              no_compress == 1)) {
 516                                 btrfs_info(root->fs_info,
 517                                            "%s %s compression",
 518                                            (compress_force) ? "force" : "use",
 519                                            compress_type);
 520                         }
 521                         compress_force = false;
 522                         break;
 523                 case Opt_ssd:
 524                         btrfs_set_and_info(root, SSD,
 525                                            "use ssd allocation scheme");
 526                         break;
 527                 case Opt_ssd_spread:
 528                         btrfs_set_and_info(root, SSD_SPREAD,
 529                                            "use spread ssd allocation scheme");
 530                         btrfs_set_opt(info->mount_opt, SSD);
 531                         break;
 532                 case Opt_nossd:
 533                         btrfs_set_and_info(root, NOSSD,
 534                                              "not using ssd allocation scheme");
 535                         btrfs_clear_opt(info->mount_opt, SSD);
 536                         break;
 537                 case Opt_barrier:
 538                         btrfs_clear_and_info(root, NOBARRIER,
 539                                              "turning on barriers");
 540                         break;
 541                 case Opt_nobarrier:
 542                         btrfs_set_and_info(root, NOBARRIER,
 543                                            "turning off barriers");
 544                         break;
 545                 case Opt_thread_pool:
 546                         ret = match_int(&args[0], &intarg);
 547                         if (ret) {
 548                                 goto out;
 549                         } else if (intarg > 0) {
 550                                 info->thread_pool_size = intarg;
 551                         } else {
 552                                 ret = -EINVAL;
 553                                 goto out;
 554                         }
 555                         break;
 556                 case Opt_max_inline:
 557                         num = match_strdup(&args[0]);
 558                         if (num) {
 559                                 info->max_inline = memparse(num, NULL);
 560                                 kfree(num);
 561
 562                                 if (info->max_inline) {
 563                                         info->max_inline = min_t(u64,
 564                                                 info->max_inline,
 565                                                 root->sectorsize);
 566                                 }
 567                                 btrfs_info(root->fs_info, "max_inline at %llu",
 568                                         info->max_inline);
 569                         } else {
 570                                 ret = -ENOMEM;
 571                                 goto out;
 572                         }
 573                         break;
 574                 case Opt_alloc_start:
 575                         num = match_strdup(&args[0]);
 576                         if (num) {
 577                                 mutex_lock(&info->chunk_mutex);
 578                                 info->alloc_start = memparse(num, NULL);
 579                                 mutex_unlock(&info->chunk_mutex);
 580                                 kfree(num);
 581                                 btrfs_info(root->fs_info, "allocations start at %llu",
 582                                         info->alloc_start);
 583                         } else {
 584                                 ret = -ENOMEM;
 585                                 goto out;
 586                         }
 587                         break;
 588                 case Opt_acl:
 589 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 590                         root->fs_info->sb->s_flags |= MS_POSIXACL;
 591                         break;
 592 #else
 593                         btrfs_err(root->fs_info,
 594                                 "support for ACL not compiled in!");
 595                         ret = -EINVAL;
 596                         goto out;
 597 #endif
 598                 case Opt_noacl:
 599                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 600                         break;
 601                 case Opt_notreelog:
 602                         btrfs_set_and_info(root, NOTREELOG,
 603                                            "disabling tree log");
 604                         break;
 605                 case Opt_treelog:
 606                         btrfs_clear_and_info(root, NOTREELOG,
 607                                              "enabling tree log");
 608                         break;
 609                 case Opt_flushoncommit:
 610                         btrfs_set_and_info(root, FLUSHONCOMMIT,
 611                                            "turning on flush-on-commit");
 612                         break;
 613                 case Opt_noflushoncommit:
 614                         btrfs_clear_and_info(root, FLUSHONCOMMIT,
 615                                              "turning off flush-on-commit");
 616                         break;
 617                 case Opt_ratio:
 618                         ret = match_int(&args[0], &intarg);
 619                         if (ret) {
 620                                 goto out;
 621                         } else if (intarg >= 0) {
 622                                 info->metadata_ratio = intarg;
 623                                 btrfs_info(root->fs_info, "metadata ratio %d",
 624                                        info->metadata_ratio);
 625                         } else {
 626                                 ret = -EINVAL;
 627                                 goto out;
 628                         }
 629                         break;
 630                 case Opt_discard:
 631                         btrfs_set_and_info(root, DISCARD,
 632                                            "turning on discard");
 633                         break;
 634                 case Opt_nodiscard:
 635                         btrfs_clear_and_info(root, DISCARD,
 636                                              "turning off discard");
 637                         break;
 638                 case Opt_space_cache:
 639                 case Opt_space_cache_version:
 640                         if (token == Opt_space_cache ||
 641                             strcmp(args[0].from, "v1") == 0) {
 642                                 btrfs_clear_opt(root->fs_info->mount_opt,
 643                                                 FREE_SPACE_TREE);
 644                                 btrfs_set_and_info(root, SPACE_CACHE,
 645                                                    "enabling disk space caching");
 646                         } else if (strcmp(args[0].from, "v2") == 0) {
 647                                 btrfs_clear_opt(root->fs_info->mount_opt,
 648                                                 SPACE_CACHE);
 649                                 btrfs_set_and_info(root, FREE_SPACE_TREE,
 650                                                    "enabling free space tree");
 651                         } else {
 652                                 ret = -EINVAL;
 653                                 goto out;
 654                         }
 655                         break;
 656                 case Opt_rescan_uuid_tree:
 657                         btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
 658                         break;
 659                 case Opt_no_space_cache:
 660                         if (btrfs_test_opt(root, SPACE_CACHE)) {
 661                                 btrfs_clear_and_info(root, SPACE_CACHE,
 662                                                      "disabling disk space caching");
 663                         }
 664                         if (btrfs_test_opt(root, FREE_SPACE_TREE)) {
 665                                 btrfs_clear_and_info(root, FREE_SPACE_TREE,
 666                                                      "disabling free space tree");
 667                         }
 668                         break;
 669                 case Opt_inode_cache:
 670                         btrfs_set_pending_and_info(info, INODE_MAP_CACHE,
 671                                            "enabling inode map caching");
 672                         break;
 673                 case Opt_noinode_cache:
 674                         btrfs_clear_pending_and_info(info, INODE_MAP_CACHE,
 675                                              "disabling inode map caching");
 676                         break;
 677                 case Opt_clear_cache:
 678                         btrfs_set_and_info(root, CLEAR_CACHE,
 679                                            "force clearing of disk cache");
 680                         break;
 681                 case Opt_user_subvol_rm_allowed:
 682                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 683                         break;
 684                 case Opt_enospc_debug:
 685                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 686                         break;
 687                 case Opt_noenospc_debug:
 688                         btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
 689                         break;
 690                 case Opt_defrag:
 691                         btrfs_set_and_info(root, AUTO_DEFRAG,
 692                                            "enabling auto defrag");
 693                         break;
 694                 case Opt_nodefrag:
 695                         btrfs_clear_and_info(root, AUTO_DEFRAG,
 696                                              "disabling auto defrag");
 697                         break;
 698                 case Opt_recovery:
 699                         btrfs_info(root->fs_info, "enabling auto recovery");
 700                         btrfs_set_opt(info->mount_opt, RECOVERY);
 701                         break;
 702                 case Opt_skip_balance:
 703                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 704                         break;
 705 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 706                 case Opt_check_integrity_including_extent_data:
 707                         btrfs_info(root->fs_info,
 708                                    "enabling check integrity including extent data");
 709                         btrfs_set_opt(info->mount_opt,
 710                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 711                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 712                         break;
 713                 case Opt_check_integrity:
 714                         btrfs_info(root->fs_info, "enabling check integrity");
 715                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 716                         break;
 717                 case Opt_check_integrity_print_mask:
 718                         ret = match_int(&args[0], &intarg);
 719                         if (ret) {
 720                                 goto out;
 721                         } else if (intarg >= 0) {
 722                                 info->check_integrity_print_mask = intarg;
 723                                 btrfs_info(root->fs_info, "check_integrity_print_mask 0x%x",
 724                                        info->check_integrity_print_mask);
 725                         } else {
 726                                 ret = -EINVAL;
 727                                 goto out;
 728                         }
 729                         break;
 730 #else
 731                 case Opt_check_integrity_including_extent_data:
 732                 case Opt_check_integrity:
 733                 case Opt_check_integrity_print_mask:
 734                         btrfs_err(root->fs_info,
 735                                 "support for check_integrity* not compiled in!");
 736                         ret = -EINVAL;
 737                         goto out;
 738 #endif
 739                 case Opt_fatal_errors:
 740                         if (strcmp(args[0].from, "panic") == 0)
 741                                 btrfs_set_opt(info->mount_opt,
 742                                               PANIC_ON_FATAL_ERROR);
 743                         else if (strcmp(args[0].from, "bug") == 0)
 744                                 btrfs_clear_opt(info->mount_opt,
 745                                               PANIC_ON_FATAL_ERROR);
 746                         else {
 747                                 ret = -EINVAL;
 748                                 goto out;
 749                         }
 750                         break;
 751                 case Opt_commit_interval:
 752                         intarg = 0;
 753                         ret = match_int(&args[0], &intarg);
 754                         if (ret < 0) {
 755                                 btrfs_err(root->fs_info, "invalid commit interval");
 756                                 ret = -EINVAL;
 757                                 goto out;
 758                         }
 759                         if (intarg > 0) {
 760                                 if (intarg > 300) {
 761                                         btrfs_warn(root->fs_info, "excessive commit interval %d",
 762                                                         intarg);
 763                                 }
 764                                 info->commit_interval = intarg;
 765                         } else {
 766                                 btrfs_info(root->fs_info, "using default commit interval %ds",
 767                                     BTRFS_DEFAULT_COMMIT_INTERVAL);
 768                                 info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
 769                         }
 770                         break;
 771 #ifdef CONFIG_BTRFS_DEBUG
 772                 case Opt_fragment_all:
 773                         btrfs_info(root->fs_info, "fragmenting all space");
 774                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 775                         btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
 776                         break;
 777                 case Opt_fragment_metadata:
 778                         btrfs_info(root->fs_info, "fragmenting metadata");
 779                         btrfs_set_opt(info->mount_opt,
 780                                       FRAGMENT_METADATA);
 781                         break;
 782                 case Opt_fragment_data:
 783                         btrfs_info(root->fs_info, "fragmenting data");
 784                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
 785                         break;
 786 #endif
 787                 case Opt_err:
 788                         btrfs_info(root->fs_info, "unrecognized mount option '%s'", p);
 789                         ret = -EINVAL;
 790                         goto out;
 791                 default:
 792                         break;
 793                 }
 794         }
 795 out:
 796         if (btrfs_fs_compat_ro(root->fs_info, FREE_SPACE_TREE) &&
 797             !btrfs_test_opt(root, FREE_SPACE_TREE) &&
 798             !btrfs_test_opt(root, CLEAR_CACHE)) {
 799                 btrfs_err(root->fs_info, "cannot disable free space tree");
 800                 ret = -EINVAL;
 801
 802         }
 803         if (!ret && btrfs_test_opt(root, SPACE_CACHE))
 804                 btrfs_info(root->fs_info, "disk space caching is enabled");
 805         if (!ret && btrfs_test_opt(root, FREE_SPACE_TREE))
 806                 btrfs_info(root->fs_info, "using free space tree");
 807         kfree(orig);
 808         return ret;
 809 }
 810
 811 /*
 812  * Parse mount options that are required early in the mount process.
 813  *
 814  * All other options will be parsed on much later in the mount process and
 815  * only when we need to allocate a new super block.
 816  */
 817 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 818                 void *holder, char **subvol_name, u64 *subvol_objectid,
 819                 struct btrfs_fs_devices **fs_devices)
 820 {
 821         substring_t args[MAX_OPT_ARGS];
 822         char *device_name, *opts, *orig, *p;
 823         char *num = NULL;
 824         int error = 0;
 825
 826         if (!options)
 827                 return 0;
 828
 829         /*
 830          * strsep changes the string, duplicate it because parse_options
 831          * gets called twice
 832          */
 833         opts = kstrdup(options, GFP_KERNEL);
 834         if (!opts)
 835                 return -ENOMEM;
 836         orig = opts;
 837
 838         while ((p = strsep(&opts, ",")) != NULL) {
 839                 int token;
 840                 if (!*p)
 841                         continue;
 842
 843                 token = match_token(p, tokens, args);
 844                 switch (token) {
 845                 case Opt_subvol:
 846                         kfree(*subvol_name);
 847                         *subvol_name = match_strdup(&args[0]);
 848                         if (!*subvol_name) {
 849                                 error = -ENOMEM;
 850                                 goto out;
 851                         }
 852                         break;
 853                 case Opt_subvolid:
 854                         num = match_strdup(&args[0]);
 855                         if (num) {
 856                                 *subvol_objectid = memparse(num, NULL);
 857                                 kfree(num);
 858                                 /* we want the original fs_tree */
 859                                 if (!*subvol_objectid)
 860                                         *subvol_objectid =
 861                                                 BTRFS_FS_TREE_OBJECTID;
 862                         } else {
 863                                 error = -EINVAL;
 864                                 goto out;
 865                         }
 866                         break;
 867                 case Opt_subvolrootid:
 868                         printk(KERN_WARNING
 869                                 "BTRFS: 'subvolrootid' mount option is deprecated and has "
 870                                 "no effect\n");
 871                         break;
 872                 case Opt_device:
 873                         device_name = match_strdup(&args[0]);
 874                         if (!device_name) {
 875                                 error = -ENOMEM;
 876                                 goto out;
 877                         }
 878                         error = btrfs_scan_one_device(device_name,
 879                                         flags, holder, fs_devices);
 880                         kfree(device_name);
 881                         if (error)
 882                                 goto out;
 883                         break;
 884                 default:
 885                         break;
 886                 }
 887         }
 888
 889 out:
 890         kfree(orig);
 891         return error;
 892 }
 893
 894 static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 895                                            u64 subvol_objectid)
 896 {
 897         struct btrfs_root *root = fs_info->tree_root;
 898         struct btrfs_root *fs_root;
 899         struct btrfs_root_ref *root_ref;
 900         struct btrfs_inode_ref *inode_ref;
 901         struct btrfs_key key;
 902         struct btrfs_path *path = NULL;
 903         char *name = NULL, *ptr;
 904         u64 dirid;
 905         int len;
 906         int ret;
 907
 908         path = btrfs_alloc_path();
 909         if (!path) {
 910                 ret = -ENOMEM;
 911                 goto err;
 912         }
 913         path->leave_spinning = 1;
 914
 915         name = kmalloc(PATH_MAX, GFP_NOFS);
 916         if (!name) {
 917                 ret = -ENOMEM;
 918                 goto err;
 919         }
 920         ptr = name + PATH_MAX - 1;
 921         ptr[0] = '\0';
 922
 923         /*
 924          * Walk up the subvolume trees in the tree of tree roots by root
 925          * backrefs until we hit the top-level subvolume.
 926          */
 927         while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
 928                 key.objectid = subvol_objectid;
 929                 key.type = BTRFS_ROOT_BACKREF_KEY;
 930                 key.offset = (u64)-1;
 931
 932                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 933                 if (ret < 0) {
 934                         goto err;
 935                 } else if (ret > 0) {
 936                         ret = btrfs_previous_item(root, path, subvol_objectid,
 937                                                   BTRFS_ROOT_BACKREF_KEY);
 938                         if (ret < 0) {
 939                                 goto err;
 940                         } else if (ret > 0) {
 941                                 ret = -ENOENT;
 942                                 goto err;
 943                         }
 944                 }
 945
 946                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 947                 subvol_objectid = key.offset;
 948
 949                 root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 950                                           struct btrfs_root_ref);
 951                 len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
 952                 ptr -= len + 1;
 953                 if (ptr < name) {
 954                         ret = -ENAMETOOLONG;
 955                         goto err;
 956                 }
 957                 read_extent_buffer(path->nodes[0], ptr + 1,
 958                                    (unsigned long)(root_ref + 1), len);
 959                 ptr[0] = '/';
 960                 dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
 961                 btrfs_release_path(path);
 962
 963                 key.objectid = subvol_objectid;
 964                 key.type = BTRFS_ROOT_ITEM_KEY;
 965                 key.offset = (u64)-1;
 966                 fs_root = btrfs_read_fs_root_no_name(fs_info, &key);
 967                 if (IS_ERR(fs_root)) {
 968                         ret = PTR_ERR(fs_root);
 969                         goto err;
 970                 }
 971
 972                 /*
 973                  * Walk up the filesystem tree by inode refs until we hit the
 974                  * root directory.
 975                  */
 976                 while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
 977                         key.objectid = dirid;
 978                         key.type = BTRFS_INODE_REF_KEY;
 979                         key.offset = (u64)-1;
 980
 981                         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
 982                         if (ret < 0) {
 983                                 goto err;
 984                         } else if (ret > 0) {
 985                                 ret = btrfs_previous_item(fs_root, path, dirid,
 986                                                           BTRFS_INODE_REF_KEY);
 987                                 if (ret < 0) {
 988                                         goto err;
 989                                 } else if (ret > 0) {
 990                                         ret = -ENOENT;
 991                                         goto err;
 992                                 }
 993                         }
 994
 995                         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 996                         dirid = key.offset;
 997
 998                         inode_ref = btrfs_item_ptr(path->nodes[0],
 999                                                    path->slots[0],
1000                                                    struct btrfs_inode_ref);
1001                         len = btrfs_inode_ref_name_len(path->nodes[0],
1002                                                        inode_ref);
1003                         ptr -= len + 1;
1004                         if (ptr < name) {
1005                                 ret = -ENAMETOOLONG;
1006                                 goto err;
1007                         }
1008                         read_extent_buffer(path->nodes[0], ptr + 1,
1009                                            (unsigned long)(inode_ref + 1), len);
1010                         ptr[0] = '/';
1011                         btrfs_release_path(path);
1012                 }
1013         }
1014
1015         btrfs_free_path(path);
1016         if (ptr == name + PATH_MAX - 1) {
1017                 name[0] = '/';
1018                 name[1] = '\0';
1019         } else {
1020                 memmove(name, ptr, name + PATH_MAX - ptr);
1021         }
1022         return name;
1023
1024 err:
1025         btrfs_free_path(path);
1026         kfree(name);
1027         return ERR_PTR(ret);
1028 }
1029
1030 static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
1031 {
1032         struct btrfs_root *root = fs_info->tree_root;
1033         struct btrfs_dir_item *di;
1034         struct btrfs_path *path;
1035         struct btrfs_key location;
1036         u64 dir_id;
1037
1038         path = btrfs_alloc_path();
1039         if (!path)
1040                 return -ENOMEM;
1041         path->leave_spinning = 1;
1042
1043         /*
1044          * Find the "default" dir item which points to the root item that we
1045          * will mount by default if we haven't been given a specific subvolume
1046          * to mount.
1047          */
1048         dir_id = btrfs_super_root_dir(fs_info->super_copy);
1049         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
1050         if (IS_ERR(di)) {
1051                 btrfs_free_path(path);
1052                 return PTR_ERR(di);
1053         }
1054         if (!di) {
1055                 /*
1056                  * Ok the default dir item isn't there.  This is weird since
1057                  * it's always been there, but don't freak out, just try and
1058                  * mount the top-level subvolume.
1059                  */
1060                 btrfs_free_path(path);
1061                 *objectid = BTRFS_FS_TREE_OBJECTID;
1062                 return 0;
1063         }
1064
1065         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
1066         btrfs_free_path(path);
1067         *objectid = location.objectid;
1068         return 0;
1069 }
1070
1071 static int btrfs_fill_super(struct super_block *sb,
1072                             struct btrfs_fs_devices *fs_devices,
1073                             void *data, int silent)
1074 {
1075         struct inode *inode;
1076         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1077         struct btrfs_key key;
1078         int err;
1079
1080         sb->s_maxbytes = MAX_LFS_FILESIZE;
1081         sb->s_magic = BTRFS_SUPER_MAGIC;
1082         sb->s_op = &btrfs_super_ops;
1083         sb->s_d_op = &btrfs_dentry_operations;
1084         sb->s_export_op = &btrfs_export_ops;
1085         sb->s_xattr = btrfs_xattr_handlers;
1086         sb->s_time_gran = 1;
1087 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
1088         sb->s_flags |= MS_POSIXACL;
1089 #endif
1090         sb->s_flags |= MS_I_VERSION;
1091         sb->s_iflags |= SB_I_CGROUPWB;
1092         err = open_ctree(sb, fs_devices, (char *)data);
1093         if (err) {
1094                 printk(KERN_ERR "BTRFS: open_ctree failed\n");
1095                 return err;
1096         }
1097
1098         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
1099         key.type = BTRFS_INODE_ITEM_KEY;
1100         key.offset = 0;
1101         inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
1102         if (IS_ERR(inode)) {
1103                 err = PTR_ERR(inode);
1104                 goto fail_close;
1105         }
1106
1107         sb->s_root = d_make_root(inode);
1108         if (!sb->s_root) {
1109                 err = -ENOMEM;
1110                 goto fail_close;
1111         }
1112
1113         save_mount_options(sb, data);
1114         cleancache_init_fs(sb);
1115         sb->s_flags |= MS_ACTIVE;
1116         return 0;
1117
1118 fail_close:
1119         close_ctree(fs_info->tree_root);
1120         return err;
1121 }
1122
1123 int btrfs_sync_fs(struct super_block *sb, int wait)
1124 {
1125         struct btrfs_trans_handle *trans;
1126         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1127         struct btrfs_root *root = fs_info->tree_root;
1128
1129         trace_btrfs_sync_fs(wait);
1130
1131         if (!wait) {
1132                 filemap_flush(fs_info->btree_inode->i_mapping);
1133                 return 0;
1134         }
1135
1136         btrfs_wait_ordered_roots(fs_info, -1);
1137
1138         trans = btrfs_attach_transaction_barrier(root);
1139         if (IS_ERR(trans)) {
1140                 /* no transaction, don't bother */
1141                 if (PTR_ERR(trans) == -ENOENT) {
1142                         /*
1143                          * Exit unless we have some pending changes
1144                          * that need to go through commit
1145                          */
1146                         if (fs_info->pending_changes == 0)
1147                                 return 0;
1148                         /*
1149                          * A non-blocking test if the fs is frozen. We must not
1150                          * start a new transaction here otherwise a deadlock
1151                          * happens. The pending operations are delayed to the
1152                          * next commit after thawing.
1153                          */
1154                         if (__sb_start_write(sb, SB_FREEZE_WRITE, false))
1155                                 __sb_end_write(sb, SB_FREEZE_WRITE);
1156                         else
1157                                 return 0;
1158                         trans = btrfs_start_transaction(root, 0);
1159                 }
1160                 if (IS_ERR(trans))
1161                         return PTR_ERR(trans);
1162         }
1163         return btrfs_commit_transaction(trans, root);
1164 }
1165
1166 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1167 {
1168         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1169         struct btrfs_root *root = info->tree_root;
1170         char *compress_type;
1171
1172         if (btrfs_test_opt(root, DEGRADED))
1173                 seq_puts(seq, ",degraded");
1174         if (btrfs_test_opt(root, NODATASUM))
1175                 seq_puts(seq, ",nodatasum");
1176         if (btrfs_test_opt(root, NODATACOW))
1177                 seq_puts(seq, ",nodatacow");
1178         if (btrfs_test_opt(root, NOBARRIER))
1179                 seq_puts(seq, ",nobarrier");
1180         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1181                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
1182         if (info->alloc_start != 0)
1183                 seq_printf(seq, ",alloc_start=%llu", info->alloc_start);
1184         if (info->thread_pool_size !=  min_t(unsigned long,
1185                                              num_online_cpus() + 2, 8))
1186                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
1187         if (btrfs_test_opt(root, COMPRESS)) {
1188                 if (info->compress_type == BTRFS_COMPRESS_ZLIB)
1189                         compress_type = "zlib";
1190                 else
1191                         compress_type = "lzo";
1192                 if (btrfs_test_opt(root, FORCE_COMPRESS))
1193                         seq_printf(seq, ",compress-force=%s", compress_type);
1194                 else
1195                         seq_printf(seq, ",compress=%s", compress_type);
1196         }
1197         if (btrfs_test_opt(root, NOSSD))
1198                 seq_puts(seq, ",nossd");
1199         if (btrfs_test_opt(root, SSD_SPREAD))
1200                 seq_puts(seq, ",ssd_spread");
1201         else if (btrfs_test_opt(root, SSD))
1202                 seq_puts(seq, ",ssd");
1203         if (btrfs_test_opt(root, NOTREELOG))
1204                 seq_puts(seq, ",notreelog");
1205         if (btrfs_test_opt(root, FLUSHONCOMMIT))
1206                 seq_puts(seq, ",flushoncommit");
1207         if (btrfs_test_opt(root, DISCARD))
1208                 seq_puts(seq, ",discard");
1209         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
1210                 seq_puts(seq, ",noacl");
1211         if (btrfs_test_opt(root, SPACE_CACHE))
1212                 seq_puts(seq, ",space_cache");
1213         else if (btrfs_test_opt(root, FREE_SPACE_TREE))
1214                 seq_puts(seq, ",space_cache=v2");
1215         else
1216                 seq_puts(seq, ",nospace_cache");
1217         if (btrfs_test_opt(root, RESCAN_UUID_TREE))
1218                 seq_puts(seq, ",rescan_uuid_tree");
1219         if (btrfs_test_opt(root, CLEAR_CACHE))
1220                 seq_puts(seq, ",clear_cache");
1221         if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
1222                 seq_puts(seq, ",user_subvol_rm_allowed");
1223         if (btrfs_test_opt(root, ENOSPC_DEBUG))
1224                 seq_puts(seq, ",enospc_debug");
1225         if (btrfs_test_opt(root, AUTO_DEFRAG))
1226                 seq_puts(seq, ",autodefrag");
1227         if (btrfs_test_opt(root, INODE_MAP_CACHE))
1228                 seq_puts(seq, ",inode_cache");
1229         if (btrfs_test_opt(root, SKIP_BALANCE))
1230                 seq_puts(seq, ",skip_balance");
1231         if (btrfs_test_opt(root, RECOVERY))
1232                 seq_puts(seq, ",recovery");
1233 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1234         if (btrfs_test_opt(root, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
1235                 seq_puts(seq, ",check_int_data");
1236         else if (btrfs_test_opt(root, CHECK_INTEGRITY))
1237                 seq_puts(seq, ",check_int");
1238         if (info->check_integrity_print_mask)
1239                 seq_printf(seq, ",check_int_print_mask=%d",
1240                                 info->check_integrity_print_mask);
1241 #endif
1242         if (info->metadata_ratio)
1243                 seq_printf(seq, ",metadata_ratio=%d",
1244                                 info->metadata_ratio);
1245         if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
1246                 seq_puts(seq, ",fatal_errors=panic");
1247         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1248                 seq_printf(seq, ",commit=%d", info->commit_interval);
1249 #ifdef CONFIG_BTRFS_DEBUG
1250         if (btrfs_test_opt(root, FRAGMENT_DATA))
1251                 seq_puts(seq, ",fragment=data");
1252         if (btrfs_test_opt(root, FRAGMENT_METADATA))
1253                 seq_puts(seq, ",fragment=metadata");
1254 #endif
1255         seq_printf(seq, ",subvolid=%llu",
1256                   BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1257         seq_puts(seq, ",subvol=");
1258         seq_dentry(seq, dentry, " \t\n\\");
1259         return 0;
1260 }
1261
1262 static int btrfs_test_super(struct super_block *s, void *data)
1263 {
1264         struct btrfs_fs_info *p = data;
1265         struct btrfs_fs_info *fs_info = btrfs_sb(s);
1266
1267         return fs_info->fs_devices == p->fs_devices;
1268 }
1269
1270 static int btrfs_set_super(struct super_block *s, void *data)
1271 {
1272         int err = set_anon_super(s, data);
1273         if (!err)
1274                 s->s_fs_info = data;
1275         return err;
1276 }
1277
1278 /*
1279  * subvolumes are identified by ino 256
1280  */
1281 static inline int is_subvolume_inode(struct inode *inode)
1282 {
1283         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1284                 return 1;
1285         return 0;
1286 }
1287
1288 /*
1289  * This will add subvolid=0 to the argument string while removing any subvol=
1290  * and subvolid= arguments to make sure we get the top-level root for path
1291  * walking to the subvol we want.
1292  */
1293 static char *setup_root_args(char *args)
1294 {
1295         char *buf, *dst, *sep;
1296
1297         if (!args)
1298                 return kstrdup("subvolid=0", GFP_NOFS);
1299
1300         /* The worst case is that we add ",subvolid=0" to the end. */
1301         buf = dst = kmalloc(strlen(args) + strlen(",subvolid=0") + 1, GFP_NOFS);
1302         if (!buf)
1303                 return NULL;
1304
1305         while (1) {
1306                 sep = strchrnul(args, ',');
1307                 if (!strstarts(args, "subvol=") &&
1308                     !strstarts(args, "subvolid=")) {
1309                         memcpy(dst, args, sep - args);
1310                         dst += sep - args;
1311                         *dst++ = ',';
1312                 }
1313                 if (*sep)
1314                         args = sep + 1;
1315                 else
1316                         break;
1317         }
1318         strcpy(dst, "subvolid=0");
1319
1320         return buf;
1321 }
1322
1323 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
1324                                    int flags, const char *device_name,
1325                                    char *data)
1326 {
1327         struct dentry *root;
1328         struct vfsmount *mnt = NULL;
1329         char *newargs;
1330         int ret;
1331
1332         newargs = setup_root_args(data);
1333         if (!newargs) {
1334                 root = ERR_PTR(-ENOMEM);
1335                 goto out;
1336         }
1337
1338         mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name, newargs);
1339         if (PTR_ERR_OR_ZERO(mnt) == -EBUSY) {
1340                 if (flags & MS_RDONLY) {
1341                         mnt = vfs_kern_mount(&btrfs_fs_type, flags & ~MS_RDONLY,
1342                                              device_name, newargs);
1343                 } else {
1344                         mnt = vfs_kern_mount(&btrfs_fs_type, flags | MS_RDONLY,
1345                                              device_name, newargs);
1346                         if (IS_ERR(mnt)) {
1347                                 root = ERR_CAST(mnt);
1348                                 mnt = NULL;
1349                                 goto out;
1350                         }
1351
1352                         down_write(&mnt->mnt_sb->s_umount);
1353                         ret = btrfs_remount(mnt->mnt_sb, &flags, NULL);
1354                         up_write(&mnt->mnt_sb->s_umount);
1355                         if (ret < 0) {
1356                                 root = ERR_PTR(ret);
1357                                 goto out;
1358                         }
1359                 }
1360         }
1361         if (IS_ERR(mnt)) {
1362                 root = ERR_CAST(mnt);
1363                 mnt = NULL;
1364                 goto out;
1365         }
1366
1367         if (!subvol_name) {
1368                 if (!subvol_objectid) {
1369                         ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
1370                                                           &subvol_objectid);
1371                         if (ret) {
1372                                 root = ERR_PTR(ret);
1373                                 goto out;
1374                         }
1375                 }
1376                 subvol_name = get_subvol_name_from_objectid(btrfs_sb(mnt->mnt_sb),
1377                                                             subvol_objectid);
1378                 if (IS_ERR(subvol_name)) {
1379                         root = ERR_CAST(subvol_name);
1380                         subvol_name = NULL;
1381                         goto out;
1382                 }
1383
1384         }
1385
1386         root = mount_subtree(mnt, subvol_name);
1387         /* mount_subtree() drops our reference on the vfsmount. */
1388         mnt = NULL;
1389
1390         if (!IS_ERR(root)) {
1391                 struct super_block *s = root->d_sb;
1392                 struct inode *root_inode = d_inode(root);
1393                 u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
1394
1395                 ret = 0;
1396                 if (!is_subvolume_inode(root_inode)) {
1397                         pr_err("BTRFS: '%s' is not a valid subvolume\n",
1398                                subvol_name);
1399                         ret = -EINVAL;
1400                 }
1401                 if (subvol_objectid && root_objectid != subvol_objectid) {
1402                         /*
1403                          * This will also catch a race condition where a
1404                          * subvolume which was passed by ID is renamed and
1405                          * another subvolume is renamed over the old location.
1406                          */
1407                         pr_err("BTRFS: subvol '%s' does not match subvolid %llu\n",
1408                                subvol_name, subvol_objectid);
1409                         ret = -EINVAL;
1410                 }
1411                 if (ret) {
1412                         dput(root);
1413                         root = ERR_PTR(ret);
1414                         deactivate_locked_super(s);
1415                 }
1416         }
1417
1418 out:
1419         mntput(mnt);
1420         kfree(newargs);
1421         kfree(subvol_name);
1422         return root;
1423 }
1424
1425 static int parse_security_options(char *orig_opts,
1426                                   struct security_mnt_opts *sec_opts)
1427 {
1428         char *secdata = NULL;
1429         int ret = 0;
1430
1431         secdata = alloc_secdata();
1432         if (!secdata)
1433                 return -ENOMEM;
1434         ret = security_sb_copy_data(orig_opts, secdata);
1435         if (ret) {
1436                 free_secdata(secdata);
1437                 return ret;
1438         }
1439         ret = security_sb_parse_opts_str(secdata, sec_opts);
1440         free_secdata(secdata);
1441         return ret;
1442 }
1443
1444 static int setup_security_options(struct btrfs_fs_info *fs_info,
1445                                   struct super_block *sb,
1446                                   struct security_mnt_opts *sec_opts)
1447 {
1448         int ret = 0;
1449
1450         /*
1451          * Call security_sb_set_mnt_opts() to check whether new sec_opts
1452          * is valid.
1453          */
1454         ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
1455         if (ret)
1456                 return ret;
1457
1458 #ifdef CONFIG_SECURITY
1459         if (!fs_info->security_opts.num_mnt_opts) {
1460                 /* first time security setup, copy sec_opts to fs_info */
1461                 memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts));
1462         } else {
1463                 /*
1464                  * Since SELinux(the only one supports security_mnt_opts) does
1465                  * NOT support changing context during remount/mount same sb,
1466                  * This must be the same or part of the same security options,
1467                  * just free it.
1468                  */
1469                 security_free_mnt_opts(sec_opts);
1470         }
1471 #endif
1472         return ret;
1473 }
1474
1475 /*
1476  * Find a superblock for the given device / mount point.
1477  *
1478  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
1479  *        for multiple device setup.  Make sure to keep it in sync.
1480  */
1481 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1482                 const char *device_name, void *data)
1483 {
1484         struct block_device *bdev = NULL;
1485         struct super_block *s;
1486         struct btrfs_fs_devices *fs_devices = NULL;
1487         struct btrfs_fs_info *fs_info = NULL;
1488         struct security_mnt_opts new_sec_opts;
1489         fmode_t mode = FMODE_READ;
1490         char *subvol_name = NULL;
1491         u64 subvol_objectid = 0;
1492         int error = 0;
1493
1494         if (!(flags & MS_RDONLY))
1495                 mode |= FMODE_WRITE;
1496
1497         error = btrfs_parse_early_options(data, mode, fs_type,
1498                                           &subvol_name, &subvol_objectid,
1499                                           &fs_devices);
1500         if (error) {
1501                 kfree(subvol_name);
1502                 return ERR_PTR(error);
1503         }
1504
1505         if (subvol_name || subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
1506                 /* mount_subvol() will free subvol_name. */
1507                 return mount_subvol(subvol_name, subvol_objectid, flags,
1508                                     device_name, data);
1509         }
1510
1511         security_init_mnt_opts(&new_sec_opts);
1512         if (data) {
1513                 error = parse_security_options(data, &new_sec_opts);
1514                 if (error)
1515                         return ERR_PTR(error);
1516         }
1517
1518         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1519         if (error)
1520                 goto error_sec_opts;
1521
1522         /*
1523          * Setup a dummy root and fs_info for test/set super.  This is because
1524          * we don't actually fill this stuff out until open_ctree, but we need
1525          * it for searching for existing supers, so this lets us do that and
1526          * then open_ctree will properly initialize everything later.
1527          */
1528         fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
1529         if (!fs_info) {
1530                 error = -ENOMEM;
1531                 goto error_sec_opts;
1532         }
1533
1534         fs_info->fs_devices = fs_devices;
1535
1536         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1537         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1538         security_init_mnt_opts(&fs_info->security_opts);
1539         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1540                 error = -ENOMEM;
1541                 goto error_fs_info;
1542         }
1543
1544         error = btrfs_open_devices(fs_devices, mode, fs_type);
1545         if (error)
1546                 goto error_fs_info;
1547
1548         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
1549                 error = -EACCES;
1550                 goto error_close_devices;
1551         }
1552
1553         bdev = fs_devices->latest_bdev;
1554         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | MS_NOSEC,
1555                  fs_info);
1556         if (IS_ERR(s)) {
1557                 error = PTR_ERR(s);
1558                 goto error_close_devices;
1559         }
1560
1561         if (s->s_root) {
1562                 btrfs_close_devices(fs_devices);
1563                 free_fs_info(fs_info);
1564                 if ((flags ^ s->s_flags) & MS_RDONLY)
1565                         error = -EBUSY;
1566         } else {
1567                 snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
1568                 btrfs_sb(s)->bdev_holder = fs_type;
1569                 error = btrfs_fill_super(s, fs_devices, data,
1570                                          flags & MS_SILENT ? 1 : 0);
1571         }
1572         if (error) {
1573                 deactivate_locked_super(s);
1574                 goto error_sec_opts;
1575         }
1576
1577         fs_info = btrfs_sb(s);
1578         error = setup_security_options(fs_info, s, &new_sec_opts);
1579         if (error) {
1580                 deactivate_locked_super(s);
1581                 goto error_sec_opts;
1582         }
1583
1584         return dget(s->s_root);
1585
1586 error_close_devices:
1587         btrfs_close_devices(fs_devices);
1588 error_fs_info:
1589         free_fs_info(fs_info);
1590 error_sec_opts:
1591         security_free_mnt_opts(&new_sec_opts);
1592         return ERR_PTR(error);
1593 }
1594
1595 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1596                                      int new_pool_size, int old_pool_size)
1597 {
1598         if (new_pool_size == old_pool_size)
1599                 return;
1600
1601         fs_info->thread_pool_size = new_pool_size;
1602
1603         btrfs_info(fs_info, "resize thread pool %d -> %d",
1604                old_pool_size, new_pool_size);
1605
1606         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1607         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1608         btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);
1609         btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1610         btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
1611         btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
1612         btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
1613                                 new_pool_size);
1614         btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1615         btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1616         btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1617         btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
1618         btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
1619                                 new_pool_size);
1620 }
1621
1622 static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
1623 {
1624         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1625 }
1626
1627 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1628                                        unsigned long old_opts, int flags)
1629 {
1630         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1631             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1632              (flags & MS_RDONLY))) {
1633                 /* wait for any defraggers to finish */
1634                 wait_event(fs_info->transaction_wait,
1635                            (atomic_read(&fs_info->defrag_running) == 0));
1636                 if (flags & MS_RDONLY)
1637                         sync_filesystem(fs_info->sb);
1638         }
1639 }
1640
1641 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1642                                          unsigned long old_opts)
1643 {
1644         /*
1645          * We need cleanup all defragable inodes if the autodefragment is
1646          * close or the fs is R/O.
1647          */
1648         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1649             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1650              (fs_info->sb->s_flags & MS_RDONLY))) {
1651                 btrfs_cleanup_defrag_inodes(fs_info);
1652         }
1653
1654         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1655 }
1656
1657 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1658 {
1659         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1660         struct btrfs_root *root = fs_info->tree_root;
1661         unsigned old_flags = sb->s_flags;
1662         unsigned long old_opts = fs_info->mount_opt;
1663         unsigned long old_compress_type = fs_info->compress_type;
1664         u64 old_max_inline = fs_info->max_inline;
1665         u64 old_alloc_start = fs_info->alloc_start;
1666         int old_thread_pool_size = fs_info->thread_pool_size;
1667         unsigned int old_metadata_ratio = fs_info->metadata_ratio;
1668         int ret;
1669
1670         sync_filesystem(sb);
1671         btrfs_remount_prepare(fs_info);
1672
1673         if (data) {
1674                 struct security_mnt_opts new_sec_opts;
1675
1676                 security_init_mnt_opts(&new_sec_opts);
1677                 ret = parse_security_options(data, &new_sec_opts);
1678                 if (ret)
1679                         goto restore;
1680                 ret = setup_security_options(fs_info, sb,
1681                                              &new_sec_opts);
1682                 if (ret) {
1683                         security_free_mnt_opts(&new_sec_opts);
1684                         goto restore;
1685                 }
1686         }
1687
1688         ret = btrfs_parse_options(root, data);
1689         if (ret) {
1690                 ret = -EINVAL;
1691                 goto restore;
1692         }
1693
1694         btrfs_remount_begin(fs_info, old_opts, *flags);
1695         btrfs_resize_thread_pool(fs_info,
1696                 fs_info->thread_pool_size, old_thread_pool_size);
1697
1698         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1699                 goto out;
1700
1701         if (*flags & MS_RDONLY) {
1702                 /*
1703                  * this also happens on 'umount -rf' or on shutdown, when
1704                  * the filesystem is busy.
1705                  */
1706                 cancel_work_sync(&fs_info->async_reclaim_work);
1707
1708                 /* wait for the uuid_scan task to finish */
1709                 down(&fs_info->uuid_tree_rescan_sem);
1710                 /* avoid complains from lockdep et al. */
1711                 up(&fs_info->uuid_tree_rescan_sem);
1712
1713                 sb->s_flags |= MS_RDONLY;
1714
1715                 /*
1716                  * Setting MS_RDONLY will put the cleaner thread to
1717                  * sleep at the next loop if it's already active.
1718                  * If it's already asleep, we'll leave unused block
1719                  * groups on disk until we're mounted read-write again
1720                  * unless we clean them up here.
1721                  */
1722                 btrfs_delete_unused_bgs(fs_info);
1723
1724                 btrfs_dev_replace_suspend_for_unmount(fs_info);
1725                 btrfs_scrub_cancel(fs_info);
1726                 btrfs_pause_balance(fs_info);
1727
1728                 ret = btrfs_commit_super(root);
1729                 if (ret)
1730                         goto restore;
1731         } else {
1732                 if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
1733                         btrfs_err(fs_info,
1734                                 "Remounting read-write after error is not allowed");
1735                         ret = -EINVAL;
1736                         goto restore;
1737                 }
1738                 if (fs_info->fs_devices->rw_devices == 0) {
1739                         ret = -EACCES;
1740                         goto restore;
1741                 }
1742
1743                 if (fs_info->fs_devices->missing_devices >
1744                      fs_info->num_tolerated_disk_barrier_failures &&
1745                     !(*flags & MS_RDONLY)) {
1746                         btrfs_warn(fs_info,
1747                                 "too many missing devices, writeable remount is not allowed");
1748                         ret = -EACCES;
1749                         goto restore;
1750                 }
1751
1752                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1753                         ret = -EINVAL;
1754                         goto restore;
1755                 }
1756
1757                 ret = btrfs_cleanup_fs_roots(fs_info);
1758                 if (ret)
1759                         goto restore;
1760
1761                 /* recover relocation */
1762                 mutex_lock(&fs_info->cleaner_mutex);
1763                 ret = btrfs_recover_relocation(root);
1764                 mutex_unlock(&fs_info->cleaner_mutex);
1765                 if (ret)
1766                         goto restore;
1767
1768                 ret = btrfs_resume_balance_async(fs_info);
1769                 if (ret)
1770                         goto restore;
1771
1772                 ret = btrfs_resume_dev_replace_async(fs_info);
1773                 if (ret) {
1774                         btrfs_warn(fs_info, "failed to resume dev_replace");
1775                         goto restore;
1776                 }
1777
1778                 if (!fs_info->uuid_root) {
1779                         btrfs_info(fs_info, "creating UUID tree");
1780                         ret = btrfs_create_uuid_tree(fs_info);
1781                         if (ret) {
1782                                 btrfs_warn(fs_info, "failed to create the UUID tree %d", ret);
1783                                 goto restore;
1784                         }
1785                 }
1786                 sb->s_flags &= ~MS_RDONLY;
1787         }
1788 out:
1789         wake_up_process(fs_info->transaction_kthread);
1790         btrfs_remount_cleanup(fs_info, old_opts);
1791         return 0;
1792
1793 restore:
1794         /* We've hit an error - don't reset MS_RDONLY */
1795         if (sb->s_flags & MS_RDONLY)
1796                 old_flags |= MS_RDONLY;
1797         sb->s_flags = old_flags;
1798         fs_info->mount_opt = old_opts;
1799         fs_info->compress_type = old_compress_type;
1800         fs_info->max_inline = old_max_inline;
1801         mutex_lock(&fs_info->chunk_mutex);
1802         fs_info->alloc_start = old_alloc_start;
1803         mutex_unlock(&fs_info->chunk_mutex);
1804         btrfs_resize_thread_pool(fs_info,
1805                 old_thread_pool_size, fs_info->thread_pool_size);
1806         fs_info->metadata_ratio = old_metadata_ratio;
1807         btrfs_remount_cleanup(fs_info, old_opts);
1808         return ret;
1809 }
1810
1811 /* Used to sort the devices by max_avail(descending sort) */
1812 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1813                                        const void *dev_info2)
1814 {
1815         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1816             ((struct btrfs_device_info *)dev_info2)->max_avail)
1817                 return -1;
1818         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1819                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1820                 return 1;
1821         else
1822         return 0;
1823 }
1824
1825 /*
1826  * sort the devices by max_avail, in which max free extent size of each device
1827  * is stored.(Descending Sort)
1828  */
1829 static inline void btrfs_descending_sort_devices(
1830                                         struct btrfs_device_info *devices,
1831                                         size_t nr_devices)
1832 {
1833         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1834              btrfs_cmp_device_free_bytes, NULL);
1835 }
1836
1837 /*
1838  * The helper to calc the free space on the devices that can be used to store
1839  * file data.
1840  */
1841 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
1842 {
1843         struct btrfs_fs_info *fs_info = root->fs_info;
1844         struct btrfs_device_info *devices_info;
1845         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1846         struct btrfs_device *device;
1847         u64 skip_space;
1848         u64 type;
1849         u64 avail_space;
1850         u64 used_space;
1851         u64 min_stripe_size;
1852         int min_stripes = 1, num_stripes = 1;
1853         int i = 0, nr_devices;
1854         int ret;
1855
1856         /*
1857          * We aren't under the device list lock, so this is racey-ish, but good
1858          * enough for our purposes.
1859          */
1860         nr_devices = fs_info->fs_devices->open_devices;
1861         if (!nr_devices) {
1862                 smp_mb();
1863                 nr_devices = fs_info->fs_devices->open_devices;
1864                 ASSERT(nr_devices);
1865                 if (!nr_devices) {
1866                         *free_bytes = 0;
1867                         return 0;
1868                 }
1869         }
1870
1871         devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
1872                                GFP_NOFS);
1873         if (!devices_info)
1874                 return -ENOMEM;
1875
1876         /* calc min stripe number for data space alloction */
1877         type = btrfs_get_alloc_profile(root, 1);
1878         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1879                 min_stripes = 2;
1880                 num_stripes = nr_devices;
1881         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1882                 min_stripes = 2;
1883                 num_stripes = 2;
1884         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1885                 min_stripes = 4;
1886                 num_stripes = 4;
1887         }
1888
1889         if (type & BTRFS_BLOCK_GROUP_DUP)
1890                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1891         else
1892                 min_stripe_size = BTRFS_STRIPE_LEN;
1893
1894         if (fs_info->alloc_start)
1895                 mutex_lock(&fs_devices->device_list_mutex);
1896         rcu_read_lock();
1897         list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
1898                 if (!device->in_fs_metadata || !device->bdev ||
1899                     device->is_tgtdev_for_dev_replace)
1900                         continue;
1901
1902                 if (i >= nr_devices)
1903                         break;
1904
1905                 avail_space = device->total_bytes - device->bytes_used;
1906
1907                 /* align with stripe_len */
1908                 avail_space = div_u64(avail_space, BTRFS_STRIPE_LEN);
1909                 avail_space *= BTRFS_STRIPE_LEN;
1910
1911                 /*
1912                  * In order to avoid overwritting the superblock on the drive,
1913                  * btrfs starts at an offset of at least 1MB when doing chunk
1914                  * allocation.
1915                  */
1916                 skip_space = SZ_1M;
1917
1918                 /* user can set the offset in fs_info->alloc_start. */
1919                 if (fs_info->alloc_start &&
1920                     fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1921                     device->total_bytes) {
1922                         rcu_read_unlock();
1923                         skip_space = max(fs_info->alloc_start, skip_space);
1924
1925                         /*
1926                          * btrfs can not use the free space in
1927                          * [0, skip_space - 1], we must subtract it from the
1928                          * total. In order to implement it, we account the used
1929                          * space in this range first.
1930                          */
1931                         ret = btrfs_account_dev_extents_size(device, 0,
1932                                                              skip_space - 1,
1933                                                              &used_space);
1934                         if (ret) {
1935                                 kfree(devices_info);
1936                                 mutex_unlock(&fs_devices->device_list_mutex);
1937                                 return ret;
1938                         }
1939
1940                         rcu_read_lock();
1941
1942                         /* calc the free space in [0, skip_space - 1] */
1943                         skip_space -= used_space;
1944                 }
1945
1946                 /*
1947                  * we can use the free space in [0, skip_space - 1], subtract
1948                  * it from the total.
1949                  */
1950                 if (avail_space && avail_space >= skip_space)
1951                         avail_space -= skip_space;
1952                 else
1953                         avail_space = 0;
1954
1955                 if (avail_space < min_stripe_size)
1956                         continue;
1957
1958                 devices_info[i].dev = device;
1959                 devices_info[i].max_avail = avail_space;
1960
1961                 i++;
1962         }
1963         rcu_read_unlock();
1964         if (fs_info->alloc_start)
1965                 mutex_unlock(&fs_devices->device_list_mutex);
1966
1967         nr_devices = i;
1968
1969         btrfs_descending_sort_devices(devices_info, nr_devices);
1970
1971         i = nr_devices - 1;
1972         avail_space = 0;
1973         while (nr_devices >= min_stripes) {
1974                 if (num_stripes > nr_devices)
1975                         num_stripes = nr_devices;
1976
1977                 if (devices_info[i].max_avail >= min_stripe_size) {
1978                         int j;
1979                         u64 alloc_size;
1980
1981                         avail_space += devices_info[i].max_avail * num_stripes;
1982                         alloc_size = devices_info[i].max_avail;
1983                         for (j = i + 1 - num_stripes; j <= i; j++)
1984                                 devices_info[j].max_avail -= alloc_size;
1985                 }
1986                 i--;
1987                 nr_devices--;
1988         }
1989
1990         kfree(devices_info);
1991         *free_bytes = avail_space;
1992         return 0;
1993 }
1994
1995 /*
1996  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
1997  *
1998  * If there's a redundant raid level at DATA block groups, use the respective
1999  * multiplier to scale the sizes.
2000  *
2001  * Unused device space usage is based on simulating the chunk allocator
2002  * algorithm that respects the device sizes, order of allocations and the
2003  * 'alloc_start' value, this is a close approximation of the actual use but
2004  * there are other factors that may change the result (like a new metadata
2005  * chunk).
2006  *
2007  * If metadata is exhausted, f_bavail will be 0.
2008  *
2009  * FIXME: not accurate for mixed block groups, total and free/used are ok,
2010  * available appears slightly larger.
2011  */
2012 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
2013 {
2014         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
2015         struct btrfs_super_block *disk_super = fs_info->super_copy;
2016         struct list_head *head = &fs_info->space_info;
2017         struct btrfs_space_info *found;
2018         u64 total_used = 0;
2019         u64 total_free_data = 0;
2020         u64 total_free_meta = 0;
2021         int bits = dentry->d_sb->s_blocksize_bits;
2022         __be32 *fsid = (__be32 *)fs_info->fsid;
2023         unsigned factor = 1;
2024         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
2025         int ret;
2026         u64 thresh = 0;
2027
2028         /*
2029          * holding chunk_muext to avoid allocating new chunks, holding
2030          * device_list_mutex to avoid the device being removed
2031          */
2032         rcu_read_lock();
2033         list_for_each_entry_rcu(found, head, list) {
2034                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
2035                         int i;
2036
2037                         total_free_data += found->disk_total - found->disk_used;
2038                         total_free_data -=
2039                                 btrfs_account_ro_block_groups_free_space(found);
2040
2041                         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
2042                                 if (!list_empty(&found->block_groups[i])) {
2043                                         switch (i) {
2044                                         case BTRFS_RAID_DUP:
2045                                         case BTRFS_RAID_RAID1:
2046                                         case BTRFS_RAID_RAID10:
2047                                                 factor = 2;
2048                                         }
2049                                 }
2050                         }
2051                 }
2052                 if (found->flags & BTRFS_BLOCK_GROUP_METADATA)
2053                         total_free_meta += found->disk_total - found->disk_used;
2054
2055                 total_used += found->disk_used;
2056         }
2057
2058         rcu_read_unlock();
2059
2060         buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
2061         buf->f_blocks >>= bits;
2062         buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
2063
2064         /* Account global block reserve as used, it's in logical size already */
2065         spin_lock(&block_rsv->lock);
2066         buf->f_bfree -= block_rsv->size >> bits;
2067         spin_unlock(&block_rsv->lock);
2068
2069         buf->f_bavail = div_u64(total_free_data, factor);
2070         ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
2071         if (ret)
2072                 return ret;
2073         buf->f_bavail += div_u64(total_free_data, factor);
2074         buf->f_bavail = buf->f_bavail >> bits;
2075
2076         /*
2077          * We calculate the remaining metadata space minus global reserve. If
2078          * this is (supposedly) smaller than zero, there's no space. But this
2079          * does not hold in practice, the exhausted state happens where's still
2080          * some positive delta. So we apply some guesswork and compare the
2081          * delta to a 4M threshold.  (Practically observed delta was ~2M.)
2082          *
2083          * We probably cannot calculate the exact threshold value because this
2084          * depends on the internal reservations requested by various
2085          * operations, so some operations that consume a few metadata will
2086          * succeed even if the Avail is zero. But this is better than the other
2087          * way around.
2088          */
2089         thresh = 4 * 1024 * 1024;
2090
2091         if (total_free_meta - thresh < block_rsv->size)
2092                 buf->f_bavail = 0;
2093
2094         buf->f_type = BTRFS_SUPER_MAGIC;
2095         buf->f_bsize = dentry->d_sb->s_blocksize;
2096         buf->f_namelen = BTRFS_NAME_LEN;
2097
2098         /* We treat it as constant endianness (it doesn't matter _which_)
2099            because we want the fsid to come out the same whether mounted
2100            on a big-endian or little-endian host */
2101         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
2102         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
2103         /* Mask in the root object ID too, to disambiguate subvols */
2104         buf->f_fsid.val[0] ^= BTRFS_I(d_inode(dentry))->root->objectid >> 32;
2105         buf->f_fsid.val[1] ^= BTRFS_I(d_inode(dentry))->root->objectid;
2106
2107         return 0;
2108 }
2109
2110 static void btrfs_kill_super(struct super_block *sb)
2111 {
2112         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2113         kill_anon_super(sb);
2114         free_fs_info(fs_info);
2115 }
2116
2117 static struct file_system_type btrfs_fs_type = {
2118         .owner          = THIS_MODULE,
2119         .name           = "btrfs",
2120         .mount          = btrfs_mount,
2121         .kill_sb        = btrfs_kill_super,
2122         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2123 };
2124 MODULE_ALIAS_FS("btrfs");
2125
2126 static int btrfs_control_open(struct inode *inode, struct file *file)
2127 {
2128         /*
2129          * The control file's private_data is used to hold the
2130          * transaction when it is started and is used to keep
2131          * track of whether a transaction is already in progress.
2132          */
2133         file->private_data = NULL;
2134         return 0;
2135 }
2136
2137 /*
2138  * used by btrfsctl to scan devices when no FS is mounted
2139  */
2140 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
2141                                 unsigned long arg)
2142 {
2143         struct btrfs_ioctl_vol_args *vol;
2144         struct btrfs_fs_devices *fs_devices;
2145         int ret = -ENOTTY;
2146
2147         if (!capable(CAP_SYS_ADMIN))
2148                 return -EPERM;
2149
2150         vol = memdup_user((void __user *)arg, sizeof(*vol));
2151         if (IS_ERR(vol))
2152                 return PTR_ERR(vol);
2153
2154         switch (cmd) {
2155         case BTRFS_IOC_SCAN_DEV:
2156                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2157                                             &btrfs_fs_type, &fs_devices);
2158                 break;
2159         case BTRFS_IOC_DEVICES_READY:
2160                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2161                                             &btrfs_fs_type, &fs_devices);
2162                 if (ret)
2163                         break;
2164                 ret = !(fs_devices->num_devices == fs_devices->total_devices);
2165                 break;
2166         }
2167
2168         kfree(vol);
2169         return ret;
2170 }
2171
2172 static int btrfs_freeze(struct super_block *sb)
2173 {
2174         struct btrfs_trans_handle *trans;
2175         struct btrfs_root *root = btrfs_sb(sb)->tree_root;
2176
2177         trans = btrfs_attach_transaction_barrier(root);
2178         if (IS_ERR(trans)) {
2179                 /* no transaction, don't bother */
2180                 if (PTR_ERR(trans) == -ENOENT)
2181                         return 0;
2182                 return PTR_ERR(trans);
2183         }
2184         return btrfs_commit_transaction(trans, root);
2185 }
2186
2187 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
2188 {
2189         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
2190         struct btrfs_fs_devices *cur_devices;
2191         struct btrfs_device *dev, *first_dev = NULL;
2192         struct list_head *head;
2193         struct rcu_string *name;
2194
2195         mutex_lock(&fs_info->fs_devices->device_list_mutex);
2196         cur_devices = fs_info->fs_devices;
2197         while (cur_devices) {
2198                 head = &cur_devices->devices;
2199                 list_for_each_entry(dev, head, dev_list) {
2200                         if (dev->missing)
2201                                 continue;
2202                         if (!dev->name)
2203                                 continue;
2204                         if (!first_dev || dev->devid < first_dev->devid)
2205                                 first_dev = dev;
2206                 }
2207                 cur_devices = cur_devices->seed;
2208         }
2209
2210         if (first_dev) {
2211                 rcu_read_lock();
2212                 name = rcu_dereference(first_dev->name);
2213                 seq_escape(m, name->str, " \t\n\\");
2214                 rcu_read_unlock();
2215         } else {
2216                 WARN_ON(1);
2217         }
2218         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2219         return 0;
2220 }
2221
2222 static const struct super_operations btrfs_super_ops = {
2223         .drop_inode     = btrfs_drop_inode,
2224         .evict_inode    = btrfs_evict_inode,
2225         .put_super      = btrfs_put_super,
2226         .sync_fs        = btrfs_sync_fs,
2227         .show_options   = btrfs_show_options,
2228         .show_devname   = btrfs_show_devname,
2229         .write_inode    = btrfs_write_inode,
2230         .alloc_inode    = btrfs_alloc_inode,
2231         .destroy_inode  = btrfs_destroy_inode,
2232         .statfs         = btrfs_statfs,
2233         .remount_fs     = btrfs_remount,
2234         .freeze_fs      = btrfs_freeze,
2235 };
2236
2237 static const struct file_operations btrfs_ctl_fops = {
2238         .open = btrfs_control_open,
2239         .unlocked_ioctl  = btrfs_control_ioctl,
2240         .compat_ioctl = btrfs_control_ioctl,
2241         .owner   = THIS_MODULE,
2242         .llseek = noop_llseek,
2243 };
2244
2245 static struct miscdevice btrfs_misc = {
2246         .minor          = BTRFS_MINOR,
2247         .name           = "btrfs-control",
2248         .fops           = &btrfs_ctl_fops
2249 };
2250
2251 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2252 MODULE_ALIAS("devname:btrfs-control");
2253
2254 static int btrfs_interface_init(void)
2255 {
2256         return misc_register(&btrfs_misc);
2257 }
2258
2259 static void btrfs_interface_exit(void)
2260 {
2261         misc_deregister(&btrfs_misc);
2262 }
2263
2264 static void btrfs_print_info(void)
2265 {
2266         printk(KERN_INFO "Btrfs loaded"
2267 #ifdef CONFIG_BTRFS_DEBUG
2268                         ", debug=on"
2269 #endif
2270 #ifdef CONFIG_BTRFS_ASSERT
2271                         ", assert=on"
2272 #endif
2273 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2274                         ", integrity-checker=on"
2275 #endif
2276                         "\n");
2277 }
2278
2279 static int btrfs_run_sanity_tests(void)
2280 {
2281         int ret;
2282
2283         ret = btrfs_init_test_fs();
2284         if (ret)
2285                 return ret;
2286
2287         ret = btrfs_test_free_space_cache();
2288         if (ret)
2289                 goto out;
2290         ret = btrfs_test_extent_buffer_operations();
2291         if (ret)
2292                 goto out;
2293         ret = btrfs_test_extent_io();
2294         if (ret)
2295                 goto out;
2296         ret = btrfs_test_inodes();
2297         if (ret)
2298                 goto out;
2299         ret = btrfs_test_qgroups();
2300         if (ret)
2301                 goto out;
2302         ret = btrfs_test_free_space_tree();
2303 out:
2304         btrfs_destroy_test_fs();
2305         return ret;
2306 }
2307
2308 static int __init init_btrfs_fs(void)
2309 {
2310         int err;
2311
2312         err = btrfs_hash_init();
2313         if (err)
2314                 return err;
2315
2316         btrfs_props_init();
2317
2318         err = btrfs_init_sysfs();
2319         if (err)
2320                 goto free_hash;
2321
2322         btrfs_init_compress();
2323
2324         err = btrfs_init_cachep();
2325         if (err)
2326                 goto free_compress;
2327
2328         err = extent_io_init();
2329         if (err)
2330                 goto free_cachep;
2331
2332         err = extent_map_init();
2333         if (err)
2334                 goto free_extent_io;
2335
2336         err = ordered_data_init();
2337         if (err)
2338                 goto free_extent_map;
2339
2340         err = btrfs_delayed_inode_init();
2341         if (err)
2342                 goto free_ordered_data;
2343
2344         err = btrfs_auto_defrag_init();
2345         if (err)
2346                 goto free_delayed_inode;
2347
2348         err = btrfs_delayed_ref_init();
2349         if (err)
2350                 goto free_auto_defrag;
2351
2352         err = btrfs_prelim_ref_init();
2353         if (err)
2354                 goto free_delayed_ref;
2355
2356         err = btrfs_end_io_wq_init();
2357         if (err)
2358                 goto free_prelim_ref;
2359
2360         err = btrfs_interface_init();
2361         if (err)
2362                 goto free_end_io_wq;
2363
2364         btrfs_init_lockdep();
2365
2366         btrfs_print_info();
2367
2368         err = btrfs_run_sanity_tests();
2369         if (err)
2370                 goto unregister_ioctl;
2371
2372         err = register_filesystem(&btrfs_fs_type);
2373         if (err)
2374                 goto unregister_ioctl;
2375
2376         return 0;
2377
2378 unregister_ioctl:
2379         btrfs_interface_exit();
2380 free_end_io_wq:
2381         btrfs_end_io_wq_exit();
2382 free_prelim_ref:
2383         btrfs_prelim_ref_exit();
2384 free_delayed_ref:
2385         btrfs_delayed_ref_exit();
2386 free_auto_defrag:
2387         btrfs_auto_defrag_exit();
2388 free_delayed_inode:
2389         btrfs_delayed_inode_exit();
2390 free_ordered_data:
2391         ordered_data_exit();
2392 free_extent_map:
2393         extent_map_exit();
2394 free_extent_io:
2395         extent_io_exit();
2396 free_cachep:
2397         btrfs_destroy_cachep();
2398 free_compress:
2399         btrfs_exit_compress();
2400         btrfs_exit_sysfs();
2401 free_hash:
2402         btrfs_hash_exit();
2403         return err;
2404 }
2405
2406 static void __exit exit_btrfs_fs(void)
2407 {
2408         btrfs_destroy_cachep();
2409         btrfs_delayed_ref_exit();
2410         btrfs_auto_defrag_exit();
2411         btrfs_delayed_inode_exit();
2412         btrfs_prelim_ref_exit();
2413         ordered_data_exit();
2414         extent_map_exit();
2415         extent_io_exit();
2416         btrfs_interface_exit();
2417         btrfs_end_io_wq_exit();
2418         unregister_filesystem(&btrfs_fs_type);
2419         btrfs_exit_sysfs();
2420         btrfs_cleanup_fs_uuids();
2421         btrfs_exit_compress();
2422         btrfs_hash_exit();
2423 }
2424
2425 late_initcall(init_btrfs_fs);
2426 module_exit(exit_btrfs_fs)
2427
2428 MODULE_LICENSE("GPL");