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 "compat.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 "ioctl.h"
  51 #include "print-tree.h"
  52 #include "xattr.h"
  53 #include "volumes.h"
  54 #include "version.h"
  55 #include "export.h"
  56 #include "compression.h"
  57
  58 #define CREATE_TRACE_POINTS
  59 #include <trace/events/btrfs.h>
  60
  61 static const struct super_operations btrfs_super_ops;
  62 static struct file_system_type btrfs_fs_type;
  63
  64 static const char *btrfs_decode_error(struct btrfs_fs_info *fs_info, int errno,
  65                                       char nbuf[16])
  66 {
  67         char *errstr = NULL;
  68
  69         switch (errno) {
  70         case -EIO:
  71                 errstr = "IO failure";
  72                 break;
  73         case -ENOMEM:
  74                 errstr = "Out of memory";
  75                 break;
  76         case -EROFS:
  77                 errstr = "Readonly filesystem";
  78                 break;
  79         case -EEXIST:
  80                 errstr = "Object already exists";
  81                 break;
  82         default:
  83                 if (nbuf) {
  84                         if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
  85                                 errstr = nbuf;
  86                 }
  87                 break;
  88         }
  89
  90         return errstr;
  91 }
  92
  93 static void __save_error_info(struct btrfs_fs_info *fs_info)
  94 {
  95         /*
  96          * today we only save the error info into ram.  Long term we'll
  97          * also send it down to the disk
  98          */
  99         fs_info->fs_state = BTRFS_SUPER_FLAG_ERROR;
 100 }
 101
 102 /* NOTE:
 103  *      We move write_super stuff at umount in order to avoid deadlock
 104  *      for umount hold all lock.
 105  */
 106 static void save_error_info(struct btrfs_fs_info *fs_info)
 107 {
 108         __save_error_info(fs_info);
 109 }
 110
 111 /* btrfs handle error by forcing the filesystem readonly */
 112 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
 113 {
 114         struct super_block *sb = fs_info->sb;
 115
 116         if (sb->s_flags & MS_RDONLY)
 117                 return;
 118
 119         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 120                 sb->s_flags |= MS_RDONLY;
 121                 printk(KERN_INFO "btrfs is forced readonly\n");
 122                 __btrfs_scrub_cancel(fs_info);
 123 //              WARN_ON(1);
 124         }
 125 }
 126
 127 /*
 128  * __btrfs_std_error decodes expected errors from the caller and
 129  * invokes the approciate error response.
 130  */
 131 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
 132                        unsigned int line, int errno, const char *fmt, ...)
 133 {
 134         struct super_block *sb = fs_info->sb;
 135         char nbuf[16];
 136         const char *errstr;
 137         va_list args;
 138         va_start(args, fmt);
 139
 140         /*
 141          * Special case: if the error is EROFS, and we're already
 142          * under MS_RDONLY, then it is safe here.
 143          */
 144         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 145                 return;
 146
 147         errstr = btrfs_decode_error(fs_info, errno, nbuf);
 148         if (fmt) {
 149                 struct va_format vaf = {
 150                         .fmt = fmt,
 151                         .va = &args,
 152                 };
 153
 154                 printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: %s (%pV)\n",
 155                         sb->s_id, function, line, errstr, &vaf);
 156         } else {
 157                 printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: %s\n",
 158                         sb->s_id, function, line, errstr);
 159         }
 160
 161         /* Don't go through full error handling during mount */
 162         if (sb->s_flags & MS_BORN) {
 163                 save_error_info(fs_info);
 164                 btrfs_handle_error(fs_info);
 165         }
 166         va_end(args);
 167 }
 168
 169 const char *logtypes[] = {
 170         "emergency",
 171         "alert",
 172         "critical",
 173         "error",
 174         "warning",
 175         "notice",
 176         "info",
 177         "debug",
 178 };
 179
 180 void btrfs_printk(struct btrfs_fs_info *fs_info, const char *fmt, ...)
 181 {
 182         struct super_block *sb = fs_info->sb;
 183         char lvl[4];
 184         struct va_format vaf;
 185         va_list args;
 186         const char *type = logtypes[4];
 187
 188         va_start(args, fmt);
 189
 190         if (fmt[0] == '<' && isdigit(fmt[1]) && fmt[2] == '>') {
 191                 memcpy(lvl, fmt, 3);
 192                 lvl[3] = '\0';
 193                 fmt += 3;
 194                 type = logtypes[fmt[1] - '0'];
 195         } else
 196                 *lvl = '\0';
 197
 198         vaf.fmt = fmt;
 199         vaf.va = &args;
 200         printk("%sBTRFS %s (device %s): %pV", lvl, type, sb->s_id, &vaf);
 201 }
 202
 203 /*
 204  * We only mark the transaction aborted and then set the file system read-only.
 205  * This will prevent new transactions from starting or trying to join this
 206  * one.
 207  *
 208  * This means that error recovery at the call site is limited to freeing
 209  * any local memory allocations and passing the error code up without
 210  * further cleanup. The transaction should complete as it normally would
 211  * in the call path but will return -EIO.
 212  *
 213  * We'll complete the cleanup in btrfs_end_transaction and
 214  * btrfs_commit_transaction.
 215  */
 216 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 217                                struct btrfs_root *root, const char *function,
 218                                unsigned int line, int errno)
 219 {
 220         WARN_ONCE(1, KERN_DEBUG "btrfs: Transaction aborted");
 221         trans->aborted = errno;
 222         /* Nothing used. The other threads that have joined this
 223          * transaction may be able to continue. */
 224         if (!trans->blocks_used) {
 225                 btrfs_printk(root->fs_info, "Aborting unused transaction.\n");
 226                 return;
 227         }
 228         trans->transaction->aborted = errno;
 229         __btrfs_std_error(root->fs_info, function, line, errno, NULL);
 230 }
 231 /*
 232  * __btrfs_panic decodes unexpected, fatal errors from the caller,
 233  * issues an alert, and either panics or BUGs, depending on mount options.
 234  */
 235 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 236                    unsigned int line, int errno, const char *fmt, ...)
 237 {
 238         char nbuf[16];
 239         char *s_id = "<unknown>";
 240         const char *errstr;
 241         struct va_format vaf = { .fmt = fmt };
 242         va_list args;
 243
 244         if (fs_info)
 245                 s_id = fs_info->sb->s_id;
 246
 247         va_start(args, fmt);
 248         vaf.va = &args;
 249
 250         errstr = btrfs_decode_error(fs_info, errno, nbuf);
 251         if (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR)
 252                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (%s)\n",
 253                         s_id, function, line, &vaf, errstr);
 254
 255         printk(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (%s)\n",
 256                s_id, function, line, &vaf, errstr);
 257         va_end(args);
 258         /* Caller calls BUG() */
 259 }
 260
 261 static void btrfs_put_super(struct super_block *sb)
 262 {
 263         (void)close_ctree(btrfs_sb(sb)->tree_root);
 264         /* FIXME: need to fix VFS to return error? */
 265         /* AV: return it _where_?  ->put_super() can be triggered by any number
 266          * of async events, up to and including delivery of SIGKILL to the
 267          * last process that kept it busy.  Or segfault in the aforementioned
 268          * process...  Whom would you report that to?
 269          */
 270 }
 271
 272 enum {
 273         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 274         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 275         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 276         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 277         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 278         Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
 279         Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
 280         Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
 281         Opt_check_integrity, Opt_check_integrity_including_extent_data,
 282         Opt_check_integrity_print_mask, Opt_fatal_errors,
 283         Opt_err,
 284 };
 285
 286 static match_table_t tokens = {
 287         {Opt_degraded, "degraded"},
 288         {Opt_subvol, "subvol=%s"},
 289         {Opt_subvolid, "subvolid=%d"},
 290         {Opt_device, "device=%s"},
 291         {Opt_nodatasum, "nodatasum"},
 292         {Opt_nodatacow, "nodatacow"},
 293         {Opt_nobarrier, "nobarrier"},
 294         {Opt_max_inline, "max_inline=%s"},
 295         {Opt_alloc_start, "alloc_start=%s"},
 296         {Opt_thread_pool, "thread_pool=%d"},
 297         {Opt_compress, "compress"},
 298         {Opt_compress_type, "compress=%s"},
 299         {Opt_compress_force, "compress-force"},
 300         {Opt_compress_force_type, "compress-force=%s"},
 301         {Opt_ssd, "ssd"},
 302         {Opt_ssd_spread, "ssd_spread"},
 303         {Opt_nossd, "nossd"},
 304         {Opt_noacl, "noacl"},
 305         {Opt_notreelog, "notreelog"},
 306         {Opt_flushoncommit, "flushoncommit"},
 307         {Opt_ratio, "metadata_ratio=%d"},
 308         {Opt_discard, "discard"},
 309         {Opt_space_cache, "space_cache"},
 310         {Opt_clear_cache, "clear_cache"},
 311         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 312         {Opt_enospc_debug, "enospc_debug"},
 313         {Opt_subvolrootid, "subvolrootid=%d"},
 314         {Opt_defrag, "autodefrag"},
 315         {Opt_inode_cache, "inode_cache"},
 316         {Opt_no_space_cache, "nospace_cache"},
 317         {Opt_recovery, "recovery"},
 318         {Opt_skip_balance, "skip_balance"},
 319         {Opt_check_integrity, "check_int"},
 320         {Opt_check_integrity_including_extent_data, "check_int_data"},
 321         {Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
 322         {Opt_fatal_errors, "fatal_errors=%s"},
 323         {Opt_err, NULL},
 324 };
 325
 326 /*
 327  * Regular mount options parser.  Everything that is needed only when
 328  * reading in a new superblock is parsed here.
 329  * XXX JDM: This needs to be cleaned up for remount.
 330  */
 331 int btrfs_parse_options(struct btrfs_root *root, char *options)
 332 {
 333         struct btrfs_fs_info *info = root->fs_info;
 334         substring_t args[MAX_OPT_ARGS];
 335         char *p, *num, *orig = NULL;
 336         u64 cache_gen;
 337         int intarg;
 338         int ret = 0;
 339         char *compress_type;
 340         bool compress_force = false;
 341
 342         cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
 343         if (cache_gen)
 344                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 345
 346         if (!options)
 347                 goto out;
 348
 349         /*
 350          * strsep changes the string, duplicate it because parse_options
 351          * gets called twice
 352          */
 353         options = kstrdup(options, GFP_NOFS);
 354         if (!options)
 355                 return -ENOMEM;
 356
 357         orig = options;
 358
 359         while ((p = strsep(&options, ",")) != NULL) {
 360                 int token;
 361                 if (!*p)
 362                         continue;
 363
 364                 token = match_token(p, tokens, args);
 365                 switch (token) {
 366                 case Opt_degraded:
 367                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 368                         btrfs_set_opt(info->mount_opt, DEGRADED);
 369                         break;
 370                 case Opt_subvol:
 371                 case Opt_subvolid:
 372                 case Opt_subvolrootid:
 373                 case Opt_device:
 374                         /*
 375                          * These are parsed by btrfs_parse_early_options
 376                          * and can be happily ignored here.
 377                          */
 378                         break;
 379                 case Opt_nodatasum:
 380                         printk(KERN_INFO "btrfs: setting nodatasum\n");
 381                         btrfs_set_opt(info->mount_opt, NODATASUM);
 382                         break;
 383                 case Opt_nodatacow:
 384                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 385                         btrfs_set_opt(info->mount_opt, NODATACOW);
 386                         btrfs_set_opt(info->mount_opt, NODATASUM);
 387                         break;
 388                 case Opt_compress_force:
 389                 case Opt_compress_force_type:
 390                         compress_force = true;
 391                 case Opt_compress:
 392                 case Opt_compress_type:
 393                         if (token == Opt_compress ||
 394                             token == Opt_compress_force ||
 395                             strcmp(args[0].from, "zlib") == 0) {
 396                                 compress_type = "zlib";
 397                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 398                         } else if (strcmp(args[0].from, "lzo") == 0) {
 399                                 compress_type = "lzo";
 400                                 info->compress_type = BTRFS_COMPRESS_LZO;
 401                         } else {
 402                                 ret = -EINVAL;
 403                                 goto out;
 404                         }
 405
 406                         btrfs_set_opt(info->mount_opt, COMPRESS);
 407                         if (compress_force) {
 408                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 409                                 pr_info("btrfs: force %s compression\n",
 410                                         compress_type);
 411                         } else
 412                                 pr_info("btrfs: use %s compression\n",
 413                                         compress_type);
 414                         break;
 415                 case Opt_ssd:
 416                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 417                         btrfs_set_opt(info->mount_opt, SSD);
 418                         break;
 419                 case Opt_ssd_spread:
 420                         printk(KERN_INFO "btrfs: use spread ssd "
 421                                "allocation scheme\n");
 422                         btrfs_set_opt(info->mount_opt, SSD);
 423                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 424                         break;
 425                 case Opt_nossd:
 426                         printk(KERN_INFO "btrfs: not using ssd allocation "
 427                                "scheme\n");
 428                         btrfs_set_opt(info->mount_opt, NOSSD);
 429                         btrfs_clear_opt(info->mount_opt, SSD);
 430                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 431                         break;
 432                 case Opt_nobarrier:
 433                         printk(KERN_INFO "btrfs: turning off barriers\n");
 434                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 435                         break;
 436                 case Opt_thread_pool:
 437                         intarg = 0;
 438                         match_int(&args[0], &intarg);
 439                         if (intarg)
 440                                 info->thread_pool_size = intarg;
 441                         break;
 442                 case Opt_max_inline:
 443                         num = match_strdup(&args[0]);
 444                         if (num) {
 445                                 info->max_inline = memparse(num, NULL);
 446                                 kfree(num);
 447
 448                                 if (info->max_inline) {
 449                                         info->max_inline = max_t(u64,
 450                                                 info->max_inline,
 451                                                 root->sectorsize);
 452                                 }
 453                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 454                                         (unsigned long long)info->max_inline);
 455                         }
 456                         break;
 457                 case Opt_alloc_start:
 458                         num = match_strdup(&args[0]);
 459                         if (num) {
 460                                 info->alloc_start = memparse(num, NULL);
 461                                 kfree(num);
 462                                 printk(KERN_INFO
 463                                         "btrfs: allocations start at %llu\n",
 464                                         (unsigned long long)info->alloc_start);
 465                         }
 466                         break;
 467                 case Opt_noacl:
 468                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 469                         break;
 470                 case Opt_notreelog:
 471                         printk(KERN_INFO "btrfs: disabling tree log\n");
 472                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 473                         break;
 474                 case Opt_flushoncommit:
 475                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 476                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 477                         break;
 478                 case Opt_ratio:
 479                         intarg = 0;
 480                         match_int(&args[0], &intarg);
 481                         if (intarg) {
 482                                 info->metadata_ratio = intarg;
 483                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 484                                        info->metadata_ratio);
 485                         }
 486                         break;
 487                 case Opt_discard:
 488                         btrfs_set_opt(info->mount_opt, DISCARD);
 489                         break;
 490                 case Opt_space_cache:
 491                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 492                         break;
 493                 case Opt_no_space_cache:
 494                         printk(KERN_INFO "btrfs: disabling disk space caching\n");
 495                         btrfs_clear_opt(info->mount_opt, SPACE_CACHE);
 496                         break;
 497                 case Opt_inode_cache:
 498                         printk(KERN_INFO "btrfs: enabling inode map caching\n");
 499                         btrfs_set_opt(info->mount_opt, INODE_MAP_CACHE);
 500                         break;
 501                 case Opt_clear_cache:
 502                         printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 503                         btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
 504                         break;
 505                 case Opt_user_subvol_rm_allowed:
 506                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 507                         break;
 508                 case Opt_enospc_debug:
 509                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 510                         break;
 511                 case Opt_defrag:
 512                         printk(KERN_INFO "btrfs: enabling auto defrag");
 513                         btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
 514                         break;
 515                 case Opt_recovery:
 516                         printk(KERN_INFO "btrfs: enabling auto recovery");
 517                         btrfs_set_opt(info->mount_opt, RECOVERY);
 518                         break;
 519                 case Opt_skip_balance:
 520                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 521                         break;
 522 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 523                 case Opt_check_integrity_including_extent_data:
 524                         printk(KERN_INFO "btrfs: enabling check integrity"
 525                                " including extent data\n");
 526                         btrfs_set_opt(info->mount_opt,
 527                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 528                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 529                         break;
 530                 case Opt_check_integrity:
 531                         printk(KERN_INFO "btrfs: enabling check integrity\n");
 532                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 533                         break;
 534                 case Opt_check_integrity_print_mask:
 535                         intarg = 0;
 536                         match_int(&args[0], &intarg);
 537                         if (intarg) {
 538                                 info->check_integrity_print_mask = intarg;
 539                                 printk(KERN_INFO "btrfs:"
 540                                        " check_integrity_print_mask 0x%x\n",
 541                                        info->check_integrity_print_mask);
 542                         }
 543                         break;
 544 #else
 545                 case Opt_check_integrity_including_extent_data:
 546                 case Opt_check_integrity:
 547                 case Opt_check_integrity_print_mask:
 548                         printk(KERN_ERR "btrfs: support for check_integrity*"
 549                                " not compiled in!\n");
 550                         ret = -EINVAL;
 551                         goto out;
 552 #endif
 553                 case Opt_fatal_errors:
 554                         if (strcmp(args[0].from, "panic") == 0)
 555                                 btrfs_set_opt(info->mount_opt,
 556                                               PANIC_ON_FATAL_ERROR);
 557                         else if (strcmp(args[0].from, "bug") == 0)
 558                                 btrfs_clear_opt(info->mount_opt,
 559                                               PANIC_ON_FATAL_ERROR);
 560                         else {
 561                                 ret = -EINVAL;
 562                                 goto out;
 563                         }
 564                         break;
 565                 case Opt_err:
 566                         printk(KERN_INFO "btrfs: unrecognized mount option "
 567                                "'%s'\n", p);
 568                         ret = -EINVAL;
 569                         goto out;
 570                 default:
 571                         break;
 572                 }
 573         }
 574 out:
 575         if (!ret && btrfs_test_opt(root, SPACE_CACHE))
 576                 printk(KERN_INFO "btrfs: disk space caching is enabled\n");
 577         kfree(orig);
 578         return ret;
 579 }
 580
 581 /*
 582  * Parse mount options that are required early in the mount process.
 583  *
 584  * All other options will be parsed on much later in the mount process and
 585  * only when we need to allocate a new super block.
 586  */
 587 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 588                 void *holder, char **subvol_name, u64 *subvol_objectid,
 589                 u64 *subvol_rootid, struct btrfs_fs_devices **fs_devices)
 590 {
 591         substring_t args[MAX_OPT_ARGS];
 592         char *device_name, *opts, *orig, *p;
 593         int error = 0;
 594         int intarg;
 595
 596         if (!options)
 597                 return 0;
 598
 599         /*
 600          * strsep changes the string, duplicate it because parse_options
 601          * gets called twice
 602          */
 603         opts = kstrdup(options, GFP_KERNEL);
 604         if (!opts)
 605                 return -ENOMEM;
 606         orig = opts;
 607
 608         while ((p = strsep(&opts, ",")) != NULL) {
 609                 int token;
 610                 if (!*p)
 611                         continue;
 612
 613                 token = match_token(p, tokens, args);
 614                 switch (token) {
 615                 case Opt_subvol:
 616                         kfree(*subvol_name);
 617                         *subvol_name = match_strdup(&args[0]);
 618                         break;
 619                 case Opt_subvolid:
 620                         intarg = 0;
 621                         error = match_int(&args[0], &intarg);
 622                         if (!error) {
 623                                 /* we want the original fs_tree */
 624                                 if (!intarg)
 625                                         *subvol_objectid =
 626                                                 BTRFS_FS_TREE_OBJECTID;
 627                                 else
 628                                         *subvol_objectid = intarg;
 629                         }
 630                         break;
 631                 case Opt_subvolrootid:
 632                         intarg = 0;
 633                         error = match_int(&args[0], &intarg);
 634                         if (!error) {
 635                                 /* we want the original fs_tree */
 636                                 if (!intarg)
 637                                         *subvol_rootid =
 638                                                 BTRFS_FS_TREE_OBJECTID;
 639                                 else
 640                                         *subvol_rootid = intarg;
 641                         }
 642                         break;
 643                 case Opt_device:
 644                         device_name = match_strdup(&args[0]);
 645                         if (!device_name) {
 646                                 error = -ENOMEM;
 647                                 goto out;
 648                         }
 649                         error = btrfs_scan_one_device(device_name,
 650                                         flags, holder, fs_devices);
 651                         kfree(device_name);
 652                         if (error)
 653                                 goto out;
 654                         break;
 655                 default:
 656                         break;
 657                 }
 658         }
 659
 660 out:
 661         kfree(orig);
 662         return error;
 663 }
 664
 665 static struct dentry *get_default_root(struct super_block *sb,
 666                                        u64 subvol_objectid)
 667 {
 668         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 669         struct btrfs_root *root = fs_info->tree_root;
 670         struct btrfs_root *new_root;
 671         struct btrfs_dir_item *di;
 672         struct btrfs_path *path;
 673         struct btrfs_key location;
 674         struct inode *inode;
 675         u64 dir_id;
 676         int new = 0;
 677
 678         /*
 679          * We have a specific subvol we want to mount, just setup location and
 680          * go look up the root.
 681          */
 682         if (subvol_objectid) {
 683                 location.objectid = subvol_objectid;
 684                 location.type = BTRFS_ROOT_ITEM_KEY;
 685                 location.offset = (u64)-1;
 686                 goto find_root;
 687         }
 688
 689         path = btrfs_alloc_path();
 690         if (!path)
 691                 return ERR_PTR(-ENOMEM);
 692         path->leave_spinning = 1;
 693
 694         /*
 695          * Find the "default" dir item which points to the root item that we
 696          * will mount by default if we haven't been given a specific subvolume
 697          * to mount.
 698          */
 699         dir_id = btrfs_super_root_dir(fs_info->super_copy);
 700         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 701         if (IS_ERR(di)) {
 702                 btrfs_free_path(path);
 703                 return ERR_CAST(di);
 704         }
 705         if (!di) {
 706                 /*
 707                  * Ok the default dir item isn't there.  This is weird since
 708                  * it's always been there, but don't freak out, just try and
 709                  * mount to root most subvolume.
 710                  */
 711                 btrfs_free_path(path);
 712                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
 713                 new_root = fs_info->fs_root;
 714                 goto setup_root;
 715         }
 716
 717         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 718         btrfs_free_path(path);
 719
 720 find_root:
 721         new_root = btrfs_read_fs_root_no_name(fs_info, &location);
 722         if (IS_ERR(new_root))
 723                 return ERR_CAST(new_root);
 724
 725         if (btrfs_root_refs(&new_root->root_item) == 0)
 726                 return ERR_PTR(-ENOENT);
 727
 728         dir_id = btrfs_root_dirid(&new_root->root_item);
 729 setup_root:
 730         location.objectid = dir_id;
 731         location.type = BTRFS_INODE_ITEM_KEY;
 732         location.offset = 0;
 733
 734         inode = btrfs_iget(sb, &location, new_root, &new);
 735         if (IS_ERR(inode))
 736                 return ERR_CAST(inode);
 737
 738         /*
 739          * If we're just mounting the root most subvol put the inode and return
 740          * a reference to the dentry.  We will have already gotten a reference
 741          * to the inode in btrfs_fill_super so we're good to go.
 742          */
 743         if (!new && sb->s_root->d_inode == inode) {
 744                 iput(inode);
 745                 return dget(sb->s_root);
 746         }
 747
 748         return d_obtain_alias(inode);
 749 }
 750
 751 static int btrfs_fill_super(struct super_block *sb,
 752                             struct btrfs_fs_devices *fs_devices,
 753                             void *data, int silent)
 754 {
 755         struct inode *inode;
 756         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 757         struct btrfs_key key;
 758         int err;
 759
 760         sb->s_maxbytes = MAX_LFS_FILESIZE;
 761         sb->s_magic = BTRFS_SUPER_MAGIC;
 762         sb->s_op = &btrfs_super_ops;
 763         sb->s_d_op = &btrfs_dentry_operations;
 764         sb->s_export_op = &btrfs_export_ops;
 765         sb->s_xattr = btrfs_xattr_handlers;
 766         sb->s_time_gran = 1;
 767 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 768         sb->s_flags |= MS_POSIXACL;
 769 #endif
 770         sb->s_flags |= MS_I_VERSION;
 771         err = open_ctree(sb, fs_devices, (char *)data);
 772         if (err) {
 773                 printk("btrfs: open_ctree failed\n");
 774                 return err;
 775         }
 776
 777         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 778         key.type = BTRFS_INODE_ITEM_KEY;
 779         key.offset = 0;
 780         inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
 781         if (IS_ERR(inode)) {
 782                 err = PTR_ERR(inode);
 783                 goto fail_close;
 784         }
 785
 786         sb->s_root = d_make_root(inode);
 787         if (!sb->s_root) {
 788                 err = -ENOMEM;
 789                 goto fail_close;
 790         }
 791
 792         save_mount_options(sb, data);
 793         cleancache_init_fs(sb);
 794         sb->s_flags |= MS_ACTIVE;
 795         return 0;
 796
 797 fail_close:
 798         close_ctree(fs_info->tree_root);
 799         return err;
 800 }
 801
 802 int btrfs_sync_fs(struct super_block *sb, int wait)
 803 {
 804         struct btrfs_trans_handle *trans;
 805         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 806         struct btrfs_root *root = fs_info->tree_root;
 807         int ret;
 808
 809         trace_btrfs_sync_fs(wait);
 810
 811         if (!wait) {
 812                 filemap_flush(fs_info->btree_inode->i_mapping);
 813                 return 0;
 814         }
 815
 816         btrfs_wait_ordered_extents(root, 0, 0);
 817
 818         trans = btrfs_start_transaction(root, 0);
 819         if (IS_ERR(trans))
 820                 return PTR_ERR(trans);
 821         ret = btrfs_commit_transaction(trans, root);
 822         return ret;
 823 }
 824
 825 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 826 {
 827         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
 828         struct btrfs_root *root = info->tree_root;
 829         char *compress_type;
 830
 831         if (btrfs_test_opt(root, DEGRADED))
 832                 seq_puts(seq, ",degraded");
 833         if (btrfs_test_opt(root, NODATASUM))
 834                 seq_puts(seq, ",nodatasum");
 835         if (btrfs_test_opt(root, NODATACOW))
 836                 seq_puts(seq, ",nodatacow");
 837         if (btrfs_test_opt(root, NOBARRIER))
 838                 seq_puts(seq, ",nobarrier");
 839         if (info->max_inline != 8192 * 1024)
 840                 seq_printf(seq, ",max_inline=%llu",
 841                            (unsigned long long)info->max_inline);
 842         if (info->alloc_start != 0)
 843                 seq_printf(seq, ",alloc_start=%llu",
 844                            (unsigned long long)info->alloc_start);
 845         if (info->thread_pool_size !=  min_t(unsigned long,
 846                                              num_online_cpus() + 2, 8))
 847                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 848         if (btrfs_test_opt(root, COMPRESS)) {
 849                 if (info->compress_type == BTRFS_COMPRESS_ZLIB)
 850                         compress_type = "zlib";
 851                 else
 852                         compress_type = "lzo";
 853                 if (btrfs_test_opt(root, FORCE_COMPRESS))
 854                         seq_printf(seq, ",compress-force=%s", compress_type);
 855                 else
 856                         seq_printf(seq, ",compress=%s", compress_type);
 857         }
 858         if (btrfs_test_opt(root, NOSSD))
 859                 seq_puts(seq, ",nossd");
 860         if (btrfs_test_opt(root, SSD_SPREAD))
 861                 seq_puts(seq, ",ssd_spread");
 862         else if (btrfs_test_opt(root, SSD))
 863                 seq_puts(seq, ",ssd");
 864         if (btrfs_test_opt(root, NOTREELOG))
 865                 seq_puts(seq, ",notreelog");
 866         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 867                 seq_puts(seq, ",flushoncommit");
 868         if (btrfs_test_opt(root, DISCARD))
 869                 seq_puts(seq, ",discard");
 870         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 871                 seq_puts(seq, ",noacl");
 872         if (btrfs_test_opt(root, SPACE_CACHE))
 873                 seq_puts(seq, ",space_cache");
 874         else
 875                 seq_puts(seq, ",nospace_cache");
 876         if (btrfs_test_opt(root, CLEAR_CACHE))
 877                 seq_puts(seq, ",clear_cache");
 878         if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
 879                 seq_puts(seq, ",user_subvol_rm_allowed");
 880         if (btrfs_test_opt(root, ENOSPC_DEBUG))
 881                 seq_puts(seq, ",enospc_debug");
 882         if (btrfs_test_opt(root, AUTO_DEFRAG))
 883                 seq_puts(seq, ",autodefrag");
 884         if (btrfs_test_opt(root, INODE_MAP_CACHE))
 885                 seq_puts(seq, ",inode_cache");
 886         if (btrfs_test_opt(root, SKIP_BALANCE))
 887                 seq_puts(seq, ",skip_balance");
 888         if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
 889                 seq_puts(seq, ",fatal_errors=panic");
 890         return 0;
 891 }
 892
 893 static int btrfs_test_super(struct super_block *s, void *data)
 894 {
 895         struct btrfs_fs_info *p = data;
 896         struct btrfs_fs_info *fs_info = btrfs_sb(s);
 897
 898         return fs_info->fs_devices == p->fs_devices;
 899 }
 900
 901 static int btrfs_set_super(struct super_block *s, void *data)
 902 {
 903         int err = set_anon_super(s, data);
 904         if (!err)
 905                 s->s_fs_info = data;
 906         return err;
 907 }
 908
 909 /*
 910  * subvolumes are identified by ino 256
 911  */
 912 static inline int is_subvolume_inode(struct inode *inode)
 913 {
 914         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
 915                 return 1;
 916         return 0;
 917 }
 918
 919 /*
 920  * This will strip out the subvol=%s argument for an argument string and add
 921  * subvolid=0 to make sure we get the actual tree root for path walking to the
 922  * subvol we want.
 923  */
 924 static char *setup_root_args(char *args)
 925 {
 926         unsigned len = strlen(args) + 2 + 1;
 927         char *src, *dst, *buf;
 928
 929         /*
 930          * We need the same args as before, but with this substitution:
 931          * s!subvol=[^,]+!subvolid=0!
 932          *
 933          * Since the replacement string is up to 2 bytes longer than the
 934          * original, allocate strlen(args) + 2 + 1 bytes.
 935          */
 936
 937         src = strstr(args, "subvol=");
 938         /* This shouldn't happen, but just in case.. */
 939         if (!src)
 940                 return NULL;
 941
 942         buf = dst = kmalloc(len, GFP_NOFS);
 943         if (!buf)
 944                 return NULL;
 945
 946         /*
 947          * If the subvol= arg is not at the start of the string,
 948          * copy whatever precedes it into buf.
 949          */
 950         if (src != args) {
 951                 *src++ = '\0';
 952                 strcpy(buf, args);
 953                 dst += strlen(args);
 954         }
 955
 956         strcpy(dst, "subvolid=0");
 957         dst += strlen("subvolid=0");
 958
 959         /*
 960          * If there is a "," after the original subvol=... string,
 961          * copy that suffix into our buffer.  Otherwise, we're done.
 962          */
 963         src = strchr(src, ',');
 964         if (src)
 965                 strcpy(dst, src);
 966
 967         return buf;
 968 }
 969
 970 static struct dentry *mount_subvol(const char *subvol_name, int flags,
 971                                    const char *device_name, char *data)
 972 {
 973         struct dentry *root;
 974         struct vfsmount *mnt;
 975         char *newargs;
 976
 977         newargs = setup_root_args(data);
 978         if (!newargs)
 979                 return ERR_PTR(-ENOMEM);
 980         mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
 981                              newargs);
 982         kfree(newargs);
 983         if (IS_ERR(mnt))
 984                 return ERR_CAST(mnt);
 985
 986         root = mount_subtree(mnt, subvol_name);
 987
 988         if (!IS_ERR(root) && !is_subvolume_inode(root->d_inode)) {
 989                 struct super_block *s = root->d_sb;
 990                 dput(root);
 991                 root = ERR_PTR(-EINVAL);
 992                 deactivate_locked_super(s);
 993                 printk(KERN_ERR "btrfs: '%s' is not a valid subvolume\n",
 994                                 subvol_name);
 995         }
 996
 997         return root;
 998 }
 999
1000 /*
1001  * Find a superblock for the given device / mount point.
1002  *
1003  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
1004  *        for multiple device setup.  Make sure to keep it in sync.
1005  */
1006 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1007                 const char *device_name, void *data)
1008 {
1009         struct block_device *bdev = NULL;
1010         struct super_block *s;
1011         struct dentry *root;
1012         struct btrfs_fs_devices *fs_devices = NULL;
1013         struct btrfs_fs_info *fs_info = NULL;
1014         fmode_t mode = FMODE_READ;
1015         char *subvol_name = NULL;
1016         u64 subvol_objectid = 0;
1017         u64 subvol_rootid = 0;
1018         int error = 0;
1019
1020         if (!(flags & MS_RDONLY))
1021                 mode |= FMODE_WRITE;
1022
1023         error = btrfs_parse_early_options(data, mode, fs_type,
1024                                           &subvol_name, &subvol_objectid,
1025                                           &subvol_rootid, &fs_devices);
1026         if (error) {
1027                 kfree(subvol_name);
1028                 return ERR_PTR(error);
1029         }
1030
1031         if (subvol_name) {
1032                 root = mount_subvol(subvol_name, flags, device_name, data);
1033                 kfree(subvol_name);
1034                 return root;
1035         }
1036
1037         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1038         if (error)
1039                 return ERR_PTR(error);
1040
1041         /*
1042          * Setup a dummy root and fs_info for test/set super.  This is because
1043          * we don't actually fill this stuff out until open_ctree, but we need
1044          * it for searching for existing supers, so this lets us do that and
1045          * then open_ctree will properly initialize everything later.
1046          */
1047         fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
1048         if (!fs_info)
1049                 return ERR_PTR(-ENOMEM);
1050
1051         fs_info->fs_devices = fs_devices;
1052
1053         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1054         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1055         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1056                 error = -ENOMEM;
1057                 goto error_fs_info;
1058         }
1059
1060         error = btrfs_open_devices(fs_devices, mode, fs_type);
1061         if (error)
1062                 goto error_fs_info;
1063
1064         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
1065                 error = -EACCES;
1066                 goto error_close_devices;
1067         }
1068
1069         bdev = fs_devices->latest_bdev;
1070         s = sget(fs_type, btrfs_test_super, btrfs_set_super, fs_info);
1071         if (IS_ERR(s)) {
1072                 error = PTR_ERR(s);
1073                 goto error_close_devices;
1074         }
1075
1076         if (s->s_root) {
1077                 btrfs_close_devices(fs_devices);
1078                 free_fs_info(fs_info);
1079                 if ((flags ^ s->s_flags) & MS_RDONLY)
1080                         error = -EBUSY;
1081         } else {
1082                 char b[BDEVNAME_SIZE];
1083
1084                 s->s_flags = flags | MS_NOSEC;
1085                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
1086                 btrfs_sb(s)->bdev_holder = fs_type;
1087                 error = btrfs_fill_super(s, fs_devices, data,
1088                                          flags & MS_SILENT ? 1 : 0);
1089         }
1090
1091         root = !error ? get_default_root(s, subvol_objectid) : ERR_PTR(error);
1092         if (IS_ERR(root))
1093                 deactivate_locked_super(s);
1094
1095         return root;
1096
1097 error_close_devices:
1098         btrfs_close_devices(fs_devices);
1099 error_fs_info:
1100         free_fs_info(fs_info);
1101         return ERR_PTR(error);
1102 }
1103
1104 static void btrfs_set_max_workers(struct btrfs_workers *workers, int new_limit)
1105 {
1106         spin_lock_irq(&workers->lock);
1107         workers->max_workers = new_limit;
1108         spin_unlock_irq(&workers->lock);
1109 }
1110
1111 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1112                                      int new_pool_size, int old_pool_size)
1113 {
1114         if (new_pool_size == old_pool_size)
1115                 return;
1116
1117         fs_info->thread_pool_size = new_pool_size;
1118
1119         printk(KERN_INFO "btrfs: resize thread pool %d -> %d\n",
1120                old_pool_size, new_pool_size);
1121
1122         btrfs_set_max_workers(&fs_info->generic_worker, new_pool_size);
1123         btrfs_set_max_workers(&fs_info->workers, new_pool_size);
1124         btrfs_set_max_workers(&fs_info->delalloc_workers, new_pool_size);
1125         btrfs_set_max_workers(&fs_info->submit_workers, new_pool_size);
1126         btrfs_set_max_workers(&fs_info->caching_workers, new_pool_size);
1127         btrfs_set_max_workers(&fs_info->fixup_workers, new_pool_size);
1128         btrfs_set_max_workers(&fs_info->endio_workers, new_pool_size);
1129         btrfs_set_max_workers(&fs_info->endio_meta_workers, new_pool_size);
1130         btrfs_set_max_workers(&fs_info->endio_meta_write_workers, new_pool_size);
1131         btrfs_set_max_workers(&fs_info->endio_write_workers, new_pool_size);
1132         btrfs_set_max_workers(&fs_info->endio_freespace_worker, new_pool_size);
1133         btrfs_set_max_workers(&fs_info->delayed_workers, new_pool_size);
1134         btrfs_set_max_workers(&fs_info->readahead_workers, new_pool_size);
1135         btrfs_set_max_workers(&fs_info->scrub_workers, new_pool_size);
1136 }
1137
1138 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1139 {
1140         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1141         struct btrfs_root *root = fs_info->tree_root;
1142         unsigned old_flags = sb->s_flags;
1143         unsigned long old_opts = fs_info->mount_opt;
1144         unsigned long old_compress_type = fs_info->compress_type;
1145         u64 old_max_inline = fs_info->max_inline;
1146         u64 old_alloc_start = fs_info->alloc_start;
1147         int old_thread_pool_size = fs_info->thread_pool_size;
1148         unsigned int old_metadata_ratio = fs_info->metadata_ratio;
1149         int ret;
1150
1151         ret = btrfs_parse_options(root, data);
1152         if (ret) {
1153                 ret = -EINVAL;
1154                 goto restore;
1155         }
1156
1157         btrfs_resize_thread_pool(fs_info,
1158                 fs_info->thread_pool_size, old_thread_pool_size);
1159
1160         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1161                 return 0;
1162
1163         if (*flags & MS_RDONLY) {
1164                 sb->s_flags |= MS_RDONLY;
1165
1166                 ret = btrfs_commit_super(root);
1167                 if (ret)
1168                         goto restore;
1169         } else {
1170                 if (fs_info->fs_devices->rw_devices == 0) {
1171                         ret = -EACCES;
1172                         goto restore;
1173                 }
1174
1175                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1176                         ret = -EINVAL;
1177                         goto restore;
1178                 }
1179
1180                 ret = btrfs_cleanup_fs_roots(fs_info);
1181                 if (ret)
1182                         goto restore;
1183
1184                 /* recover relocation */
1185                 ret = btrfs_recover_relocation(root);
1186                 if (ret)
1187                         goto restore;
1188
1189                 sb->s_flags &= ~MS_RDONLY;
1190         }
1191
1192         return 0;
1193
1194 restore:
1195         /* We've hit an error - don't reset MS_RDONLY */
1196         if (sb->s_flags & MS_RDONLY)
1197                 old_flags |= MS_RDONLY;
1198         sb->s_flags = old_flags;
1199         fs_info->mount_opt = old_opts;
1200         fs_info->compress_type = old_compress_type;
1201         fs_info->max_inline = old_max_inline;
1202         fs_info->alloc_start = old_alloc_start;
1203         btrfs_resize_thread_pool(fs_info,
1204                 old_thread_pool_size, fs_info->thread_pool_size);
1205         fs_info->metadata_ratio = old_metadata_ratio;
1206         return ret;
1207 }
1208
1209 /* Used to sort the devices by max_avail(descending sort) */
1210 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1211                                        const void *dev_info2)
1212 {
1213         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1214             ((struct btrfs_device_info *)dev_info2)->max_avail)
1215                 return -1;
1216         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1217                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1218                 return 1;
1219         else
1220         return 0;
1221 }
1222
1223 /*
1224  * sort the devices by max_avail, in which max free extent size of each device
1225  * is stored.(Descending Sort)
1226  */
1227 static inline void btrfs_descending_sort_devices(
1228                                         struct btrfs_device_info *devices,
1229                                         size_t nr_devices)
1230 {
1231         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1232              btrfs_cmp_device_free_bytes, NULL);
1233 }
1234
1235 /*
1236  * The helper to calc the free space on the devices that can be used to store
1237  * file data.
1238  */
1239 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
1240 {
1241         struct btrfs_fs_info *fs_info = root->fs_info;
1242         struct btrfs_device_info *devices_info;
1243         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1244         struct btrfs_device *device;
1245         u64 skip_space;
1246         u64 type;
1247         u64 avail_space;
1248         u64 used_space;
1249         u64 min_stripe_size;
1250         int min_stripes = 1, num_stripes = 1;
1251         int i = 0, nr_devices;
1252         int ret;
1253
1254         nr_devices = fs_info->fs_devices->open_devices;
1255         BUG_ON(!nr_devices);
1256
1257         devices_info = kmalloc(sizeof(*devices_info) * nr_devices,
1258                                GFP_NOFS);
1259         if (!devices_info)
1260                 return -ENOMEM;
1261
1262         /* calc min stripe number for data space alloction */
1263         type = btrfs_get_alloc_profile(root, 1);
1264         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1265                 min_stripes = 2;
1266                 num_stripes = nr_devices;
1267         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1268                 min_stripes = 2;
1269                 num_stripes = 2;
1270         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1271                 min_stripes = 4;
1272                 num_stripes = 4;
1273         }
1274
1275         if (type & BTRFS_BLOCK_GROUP_DUP)
1276                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1277         else
1278                 min_stripe_size = BTRFS_STRIPE_LEN;
1279
1280         list_for_each_entry(device, &fs_devices->devices, dev_list) {
1281                 if (!device->in_fs_metadata || !device->bdev)
1282                         continue;
1283
1284                 avail_space = device->total_bytes - device->bytes_used;
1285
1286                 /* align with stripe_len */
1287                 do_div(avail_space, BTRFS_STRIPE_LEN);
1288                 avail_space *= BTRFS_STRIPE_LEN;
1289
1290                 /*
1291                  * In order to avoid overwritting the superblock on the drive,
1292                  * btrfs starts at an offset of at least 1MB when doing chunk
1293                  * allocation.
1294                  */
1295                 skip_space = 1024 * 1024;
1296
1297                 /* user can set the offset in fs_info->alloc_start. */
1298                 if (fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1299                     device->total_bytes)
1300                         skip_space = max(fs_info->alloc_start, skip_space);
1301
1302                 /*
1303                  * btrfs can not use the free space in [0, skip_space - 1],
1304                  * we must subtract it from the total. In order to implement
1305                  * it, we account the used space in this range first.
1306                  */
1307                 ret = btrfs_account_dev_extents_size(device, 0, skip_space - 1,
1308                                                      &used_space);
1309                 if (ret) {
1310                         kfree(devices_info);
1311                         return ret;
1312                 }
1313
1314                 /* calc the free space in [0, skip_space - 1] */
1315                 skip_space -= used_space;
1316
1317                 /*
1318                  * we can use the free space in [0, skip_space - 1], subtract
1319                  * it from the total.
1320                  */
1321                 if (avail_space && avail_space >= skip_space)
1322                         avail_space -= skip_space;
1323                 else
1324                         avail_space = 0;
1325
1326                 if (avail_space < min_stripe_size)
1327                         continue;
1328
1329                 devices_info[i].dev = device;
1330                 devices_info[i].max_avail = avail_space;
1331
1332                 i++;
1333         }
1334
1335         nr_devices = i;
1336
1337         btrfs_descending_sort_devices(devices_info, nr_devices);
1338
1339         i = nr_devices - 1;
1340         avail_space = 0;
1341         while (nr_devices >= min_stripes) {
1342                 if (num_stripes > nr_devices)
1343                         num_stripes = nr_devices;
1344
1345                 if (devices_info[i].max_avail >= min_stripe_size) {
1346                         int j;
1347                         u64 alloc_size;
1348
1349                         avail_space += devices_info[i].max_avail * num_stripes;
1350                         alloc_size = devices_info[i].max_avail;
1351                         for (j = i + 1 - num_stripes; j <= i; j++)
1352                                 devices_info[j].max_avail -= alloc_size;
1353                 }
1354                 i--;
1355                 nr_devices--;
1356         }
1357
1358         kfree(devices_info);
1359         *free_bytes = avail_space;
1360         return 0;
1361 }
1362
1363 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1364 {
1365         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
1366         struct btrfs_super_block *disk_super = fs_info->super_copy;
1367         struct list_head *head = &fs_info->space_info;
1368         struct btrfs_space_info *found;
1369         u64 total_used = 0;
1370         u64 total_free_data = 0;
1371         int bits = dentry->d_sb->s_blocksize_bits;
1372         __be32 *fsid = (__be32 *)fs_info->fsid;
1373         int ret;
1374
1375         /* holding chunk_muext to avoid allocating new chunks */
1376         mutex_lock(&fs_info->chunk_mutex);
1377         rcu_read_lock();
1378         list_for_each_entry_rcu(found, head, list) {
1379                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
1380                         total_free_data += found->disk_total - found->disk_used;
1381                         total_free_data -=
1382                                 btrfs_account_ro_block_groups_free_space(found);
1383                 }
1384
1385                 total_used += found->disk_used;
1386         }
1387         rcu_read_unlock();
1388
1389         buf->f_namelen = BTRFS_NAME_LEN;
1390         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
1391         buf->f_bfree = buf->f_blocks - (total_used >> bits);
1392         buf->f_bsize = dentry->d_sb->s_blocksize;
1393         buf->f_type = BTRFS_SUPER_MAGIC;
1394         buf->f_bavail = total_free_data;
1395         ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
1396         if (ret) {
1397                 mutex_unlock(&fs_info->chunk_mutex);
1398                 return ret;
1399         }
1400         buf->f_bavail += total_free_data;
1401         buf->f_bavail = buf->f_bavail >> bits;
1402         mutex_unlock(&fs_info->chunk_mutex);
1403
1404         /* We treat it as constant endianness (it doesn't matter _which_)
1405            because we want the fsid to come out the same whether mounted
1406            on a big-endian or little-endian host */
1407         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
1408         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
1409         /* Mask in the root object ID too, to disambiguate subvols */
1410         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
1411         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
1412
1413         return 0;
1414 }
1415
1416 static void btrfs_kill_super(struct super_block *sb)
1417 {
1418         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1419         kill_anon_super(sb);
1420         free_fs_info(fs_info);
1421 }
1422
1423 static struct file_system_type btrfs_fs_type = {
1424         .owner          = THIS_MODULE,
1425         .name           = "btrfs",
1426         .mount          = btrfs_mount,
1427         .kill_sb        = btrfs_kill_super,
1428         .fs_flags       = FS_REQUIRES_DEV,
1429 };
1430
1431 /*
1432  * used by btrfsctl to scan devices when no FS is mounted
1433  */
1434 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
1435                                 unsigned long arg)
1436 {
1437         struct btrfs_ioctl_vol_args *vol;
1438         struct btrfs_fs_devices *fs_devices;
1439         int ret = -ENOTTY;
1440
1441         if (!capable(CAP_SYS_ADMIN))
1442                 return -EPERM;
1443
1444         vol = memdup_user((void __user *)arg, sizeof(*vol));
1445         if (IS_ERR(vol))
1446                 return PTR_ERR(vol);
1447
1448         switch (cmd) {
1449         case BTRFS_IOC_SCAN_DEV:
1450                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1451                                             &btrfs_fs_type, &fs_devices);
1452                 break;
1453         }
1454
1455         kfree(vol);
1456         return ret;
1457 }
1458
1459 static int btrfs_freeze(struct super_block *sb)
1460 {
1461         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1462         mutex_lock(&fs_info->transaction_kthread_mutex);
1463         mutex_lock(&fs_info->cleaner_mutex);
1464         return 0;
1465 }
1466
1467 static int btrfs_unfreeze(struct super_block *sb)
1468 {
1469         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1470         mutex_unlock(&fs_info->cleaner_mutex);
1471         mutex_unlock(&fs_info->transaction_kthread_mutex);
1472         return 0;
1473 }
1474
1475 static void btrfs_fs_dirty_inode(struct inode *inode, int flags)
1476 {
1477         int ret;
1478
1479         ret = btrfs_dirty_inode(inode);
1480         if (ret)
1481                 printk_ratelimited(KERN_ERR "btrfs: fail to dirty inode %Lu "
1482                                    "error %d\n", btrfs_ino(inode), ret);
1483 }
1484
1485 static const struct super_operations btrfs_super_ops = {
1486         .drop_inode     = btrfs_drop_inode,
1487         .evict_inode    = btrfs_evict_inode,
1488         .put_super      = btrfs_put_super,
1489         .sync_fs        = btrfs_sync_fs,
1490         .show_options   = btrfs_show_options,
1491         .write_inode    = btrfs_write_inode,
1492         .dirty_inode    = btrfs_fs_dirty_inode,
1493         .alloc_inode    = btrfs_alloc_inode,
1494         .destroy_inode  = btrfs_destroy_inode,
1495         .statfs         = btrfs_statfs,
1496         .remount_fs     = btrfs_remount,
1497         .freeze_fs      = btrfs_freeze,
1498         .unfreeze_fs    = btrfs_unfreeze,
1499 };
1500
1501 static const struct file_operations btrfs_ctl_fops = {
1502         .unlocked_ioctl  = btrfs_control_ioctl,
1503         .compat_ioctl = btrfs_control_ioctl,
1504         .owner   = THIS_MODULE,
1505         .llseek = noop_llseek,
1506 };
1507
1508 static struct miscdevice btrfs_misc = {
1509         .minor          = BTRFS_MINOR,
1510         .name           = "btrfs-control",
1511         .fops           = &btrfs_ctl_fops
1512 };
1513
1514 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
1515 MODULE_ALIAS("devname:btrfs-control");
1516
1517 static int btrfs_interface_init(void)
1518 {
1519         return misc_register(&btrfs_misc);
1520 }
1521
1522 static void btrfs_interface_exit(void)
1523 {
1524         if (misc_deregister(&btrfs_misc) < 0)
1525                 printk(KERN_INFO "misc_deregister failed for control device");
1526 }
1527
1528 static int __init init_btrfs_fs(void)
1529 {
1530         int err;
1531
1532         err = btrfs_init_sysfs();
1533         if (err)
1534                 return err;
1535
1536         btrfs_init_compress();
1537
1538         err = btrfs_init_cachep();
1539         if (err)
1540                 goto free_compress;
1541
1542         err = extent_io_init();
1543         if (err)
1544                 goto free_cachep;
1545
1546         err = extent_map_init();
1547         if (err)
1548                 goto free_extent_io;
1549
1550         err = btrfs_delayed_inode_init();
1551         if (err)
1552                 goto free_extent_map;
1553
1554         err = btrfs_interface_init();
1555         if (err)
1556                 goto free_delayed_inode;
1557
1558         err = register_filesystem(&btrfs_fs_type);
1559         if (err)
1560                 goto unregister_ioctl;
1561
1562         btrfs_init_lockdep();
1563
1564         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
1565         return 0;
1566
1567 unregister_ioctl:
1568         btrfs_interface_exit();
1569 free_delayed_inode:
1570         btrfs_delayed_inode_exit();
1571 free_extent_map:
1572         extent_map_exit();
1573 free_extent_io:
1574         extent_io_exit();
1575 free_cachep:
1576         btrfs_destroy_cachep();
1577 free_compress:
1578         btrfs_exit_compress();
1579         btrfs_exit_sysfs();
1580         return err;
1581 }
1582
1583 static void __exit exit_btrfs_fs(void)
1584 {
1585         btrfs_destroy_cachep();
1586         btrfs_delayed_inode_exit();
1587         extent_map_exit();
1588         extent_io_exit();
1589         btrfs_interface_exit();
1590         unregister_filesystem(&btrfs_fs_type);
1591         btrfs_exit_sysfs();
1592         btrfs_cleanup_fs_uuids();
1593         btrfs_exit_compress();
1594 }
1595
1596 module_init(init_btrfs_fs)
1597 module_exit(exit_btrfs_fs)
1598
1599 MODULE_LICENSE("GPL");