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 #include "rcu-string.h"
  58
  59 #define CREATE_TRACE_POINTS
  60 #include <trace/events/btrfs.h>
  61
  62 static const struct super_operations btrfs_super_ops;
  63 static struct file_system_type btrfs_fs_type;
  64
  65 static const char *btrfs_decode_error(struct btrfs_fs_info *fs_info, int errno,
  66                                       char nbuf[16])
  67 {
  68         char *errstr = NULL;
  69
  70         switch (errno) {
  71         case -EIO:
  72                 errstr = "IO failure";
  73                 break;
  74         case -ENOMEM:
  75                 errstr = "Out of memory";
  76                 break;
  77         case -EROFS:
  78                 errstr = "Readonly filesystem";
  79                 break;
  80         case -EEXIST:
  81                 errstr = "Object already exists";
  82                 break;
  83         default:
  84                 if (nbuf) {
  85                         if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
  86                                 errstr = nbuf;
  87                 }
  88                 break;
  89         }
  90
  91         return errstr;
  92 }
  93
  94 static void __save_error_info(struct btrfs_fs_info *fs_info)
  95 {
  96         /*
  97          * today we only save the error info into ram.  Long term we'll
  98          * also send it down to the disk
  99          */
 100         fs_info->fs_state = BTRFS_SUPER_FLAG_ERROR;
 101 }
 102
 103 static void save_error_info(struct btrfs_fs_info *fs_info)
 104 {
 105         __save_error_info(fs_info);
 106 }
 107
 108 /* btrfs handle error by forcing the filesystem readonly */
 109 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
 110 {
 111         struct super_block *sb = fs_info->sb;
 112
 113         if (sb->s_flags & MS_RDONLY)
 114                 return;
 115
 116         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 117                 sb->s_flags |= MS_RDONLY;
 118                 printk(KERN_INFO "btrfs is forced readonly\n");
 119                 __btrfs_scrub_cancel(fs_info);
 120 //              WARN_ON(1);
 121         }
 122 }
 123
 124 #ifdef CONFIG_PRINTK
 125 /*
 126  * __btrfs_std_error decodes expected errors from the caller and
 127  * invokes the approciate error response.
 128  */
 129 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
 130                        unsigned int line, int errno, const char *fmt, ...)
 131 {
 132         struct super_block *sb = fs_info->sb;
 133         char nbuf[16];
 134         const char *errstr;
 135         va_list args;
 136         va_start(args, fmt);
 137
 138         /*
 139          * Special case: if the error is EROFS, and we're already
 140          * under MS_RDONLY, then it is safe here.
 141          */
 142         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 143                 return;
 144
 145         errstr = btrfs_decode_error(fs_info, errno, nbuf);
 146         if (fmt) {
 147                 struct va_format vaf = {
 148                         .fmt = fmt,
 149                         .va = &args,
 150                 };
 151
 152                 printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: %s (%pV)\n",
 153                         sb->s_id, function, line, errstr, &vaf);
 154         } else {
 155                 printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: %s\n",
 156                         sb->s_id, function, line, errstr);
 157         }
 158
 159         /* Don't go through full error handling during mount */
 160         if (sb->s_flags & MS_BORN) {
 161                 save_error_info(fs_info);
 162                 btrfs_handle_error(fs_info);
 163         }
 164         va_end(args);
 165 }
 166
 167 static const char * const logtypes[] = {
 168         "emergency",
 169         "alert",
 170         "critical",
 171         "error",
 172         "warning",
 173         "notice",
 174         "info",
 175         "debug",
 176 };
 177
 178 void btrfs_printk(struct btrfs_fs_info *fs_info, const char *fmt, ...)
 179 {
 180         struct super_block *sb = fs_info->sb;
 181         char lvl[4];
 182         struct va_format vaf;
 183         va_list args;
 184         const char *type = logtypes[4];
 185         int kern_level;
 186
 187         va_start(args, fmt);
 188
 189         kern_level = printk_get_level(fmt);
 190         if (kern_level) {
 191                 size_t size = printk_skip_level(fmt) - fmt;
 192                 memcpy(lvl, fmt,  size);
 193                 lvl[size] = '\0';
 194                 fmt += size;
 195                 type = logtypes[kern_level - '0'];
 196         } else
 197                 *lvl = '\0';
 198
 199         vaf.fmt = fmt;
 200         vaf.va = &args;
 201
 202         printk("%sBTRFS %s (device %s): %pV", lvl, type, sb->s_id, &vaf);
 203
 204         va_end(args);
 205 }
 206
 207 #else
 208
 209 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
 210                        unsigned int line, int errno, const char *fmt, ...)
 211 {
 212         struct super_block *sb = fs_info->sb;
 213
 214         /*
 215          * Special case: if the error is EROFS, and we're already
 216          * under MS_RDONLY, then it is safe here.
 217          */
 218         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 219                 return;
 220
 221         /* Don't go through full error handling during mount */
 222         if (sb->s_flags & MS_BORN) {
 223                 save_error_info(fs_info);
 224                 btrfs_handle_error(fs_info);
 225         }
 226 }
 227 #endif
 228
 229 /*
 230  * We only mark the transaction aborted and then set the file system read-only.
 231  * This will prevent new transactions from starting or trying to join this
 232  * one.
 233  *
 234  * This means that error recovery at the call site is limited to freeing
 235  * any local memory allocations and passing the error code up without
 236  * further cleanup. The transaction should complete as it normally would
 237  * in the call path but will return -EIO.
 238  *
 239  * We'll complete the cleanup in btrfs_end_transaction and
 240  * btrfs_commit_transaction.
 241  */
 242 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 243                                struct btrfs_root *root, const char *function,
 244                                unsigned int line, int errno)
 245 {
 246         WARN_ONCE(1, KERN_DEBUG "btrfs: Transaction aborted");
 247         trans->aborted = errno;
 248         /* Nothing used. The other threads that have joined this
 249          * transaction may be able to continue. */
 250         if (!trans->blocks_used) {
 251                 btrfs_printk(root->fs_info, "Aborting unused transaction.\n");
 252                 return;
 253         }
 254         trans->transaction->aborted = errno;
 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 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 262                    unsigned int line, int errno, const char *fmt, ...)
 263 {
 264         char nbuf[16];
 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(fs_info, errno, nbuf);
 277         if (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR)
 278                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (%s)\n",
 279                         s_id, function, line, &vaf, errstr);
 280
 281         printk(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (%s)\n",
 282                s_id, function, line, &vaf, errstr);
 283         va_end(args);
 284         /* Caller calls BUG() */
 285 }
 286
 287 static void btrfs_put_super(struct super_block *sb)
 288 {
 289         (void)close_ctree(btrfs_sb(sb)->tree_root);
 290         /* FIXME: need to fix VFS to return error? */
 291         /* AV: return it _where_?  ->put_super() can be triggered by any number
 292          * of async events, up to and including delivery of SIGKILL to the
 293          * last process that kept it busy.  Or segfault in the aforementioned
 294          * process...  Whom would you report that to?
 295          */
 296 }
 297
 298 enum {
 299         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 300         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 301         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 302         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 303         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 304         Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
 305         Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
 306         Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
 307         Opt_check_integrity, Opt_check_integrity_including_extent_data,
 308         Opt_check_integrity_print_mask, Opt_fatal_errors,
 309         Opt_err,
 310 };
 311
 312 static match_table_t tokens = {
 313         {Opt_degraded, "degraded"},
 314         {Opt_subvol, "subvol=%s"},
 315         {Opt_subvolid, "subvolid=%d"},
 316         {Opt_device, "device=%s"},
 317         {Opt_nodatasum, "nodatasum"},
 318         {Opt_nodatacow, "nodatacow"},
 319         {Opt_nobarrier, "nobarrier"},
 320         {Opt_max_inline, "max_inline=%s"},
 321         {Opt_alloc_start, "alloc_start=%s"},
 322         {Opt_thread_pool, "thread_pool=%d"},
 323         {Opt_compress, "compress"},
 324         {Opt_compress_type, "compress=%s"},
 325         {Opt_compress_force, "compress-force"},
 326         {Opt_compress_force_type, "compress-force=%s"},
 327         {Opt_ssd, "ssd"},
 328         {Opt_ssd_spread, "ssd_spread"},
 329         {Opt_nossd, "nossd"},
 330         {Opt_noacl, "noacl"},
 331         {Opt_notreelog, "notreelog"},
 332         {Opt_flushoncommit, "flushoncommit"},
 333         {Opt_ratio, "metadata_ratio=%d"},
 334         {Opt_discard, "discard"},
 335         {Opt_space_cache, "space_cache"},
 336         {Opt_clear_cache, "clear_cache"},
 337         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 338         {Opt_enospc_debug, "enospc_debug"},
 339         {Opt_subvolrootid, "subvolrootid=%d"},
 340         {Opt_defrag, "autodefrag"},
 341         {Opt_inode_cache, "inode_cache"},
 342         {Opt_no_space_cache, "nospace_cache"},
 343         {Opt_recovery, "recovery"},
 344         {Opt_skip_balance, "skip_balance"},
 345         {Opt_check_integrity, "check_int"},
 346         {Opt_check_integrity_including_extent_data, "check_int_data"},
 347         {Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
 348         {Opt_fatal_errors, "fatal_errors=%s"},
 349         {Opt_err, NULL},
 350 };
 351
 352 /*
 353  * Regular mount options parser.  Everything that is needed only when
 354  * reading in a new superblock is parsed here.
 355  * XXX JDM: This needs to be cleaned up for remount.
 356  */
 357 int btrfs_parse_options(struct btrfs_root *root, char *options)
 358 {
 359         struct btrfs_fs_info *info = root->fs_info;
 360         substring_t args[MAX_OPT_ARGS];
 361         char *p, *num, *orig = NULL;
 362         u64 cache_gen;
 363         int intarg;
 364         int ret = 0;
 365         char *compress_type;
 366         bool compress_force = false;
 367
 368         cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
 369         if (cache_gen)
 370                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 371
 372         if (!options)
 373                 goto out;
 374
 375         /*
 376          * strsep changes the string, duplicate it because parse_options
 377          * gets called twice
 378          */
 379         options = kstrdup(options, GFP_NOFS);
 380         if (!options)
 381                 return -ENOMEM;
 382
 383         orig = options;
 384
 385         while ((p = strsep(&options, ",")) != NULL) {
 386                 int token;
 387                 if (!*p)
 388                         continue;
 389
 390                 token = match_token(p, tokens, args);
 391                 switch (token) {
 392                 case Opt_degraded:
 393                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 394                         btrfs_set_opt(info->mount_opt, DEGRADED);
 395                         break;
 396                 case Opt_subvol:
 397                 case Opt_subvolid:
 398                 case Opt_subvolrootid:
 399                 case Opt_device:
 400                         /*
 401                          * These are parsed by btrfs_parse_early_options
 402                          * and can be happily ignored here.
 403                          */
 404                         break;
 405                 case Opt_nodatasum:
 406                         printk(KERN_INFO "btrfs: setting nodatasum\n");
 407                         btrfs_set_opt(info->mount_opt, NODATASUM);
 408                         break;
 409                 case Opt_nodatacow:
 410                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 411                         btrfs_set_opt(info->mount_opt, NODATACOW);
 412                         btrfs_set_opt(info->mount_opt, NODATASUM);
 413                         break;
 414                 case Opt_compress_force:
 415                 case Opt_compress_force_type:
 416                         compress_force = true;
 417                 case Opt_compress:
 418                 case Opt_compress_type:
 419                         if (token == Opt_compress ||
 420                             token == Opt_compress_force ||
 421                             strcmp(args[0].from, "zlib") == 0) {
 422                                 compress_type = "zlib";
 423                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 424                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 425                         } else if (strcmp(args[0].from, "lzo") == 0) {
 426                                 compress_type = "lzo";
 427                                 info->compress_type = BTRFS_COMPRESS_LZO;
 428                                 btrfs_set_opt(info->mount_opt, COMPRESS);
 429                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
 430                         } else if (strncmp(args[0].from, "no", 2) == 0) {
 431                                 compress_type = "no";
 432                                 info->compress_type = BTRFS_COMPRESS_NONE;
 433                                 btrfs_clear_opt(info->mount_opt, COMPRESS);
 434                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 435                                 compress_force = false;
 436                         } else {
 437                                 ret = -EINVAL;
 438                                 goto out;
 439                         }
 440
 441                         if (compress_force) {
 442                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 443                                 pr_info("btrfs: force %s compression\n",
 444                                         compress_type);
 445                         } else
 446                                 pr_info("btrfs: use %s compression\n",
 447                                         compress_type);
 448                         break;
 449                 case Opt_ssd:
 450                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 451                         btrfs_set_opt(info->mount_opt, SSD);
 452                         break;
 453                 case Opt_ssd_spread:
 454                         printk(KERN_INFO "btrfs: use spread ssd "
 455                                "allocation scheme\n");
 456                         btrfs_set_opt(info->mount_opt, SSD);
 457                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 458                         break;
 459                 case Opt_nossd:
 460                         printk(KERN_INFO "btrfs: not using ssd allocation "
 461                                "scheme\n");
 462                         btrfs_set_opt(info->mount_opt, NOSSD);
 463                         btrfs_clear_opt(info->mount_opt, SSD);
 464                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 465                         break;
 466                 case Opt_nobarrier:
 467                         printk(KERN_INFO "btrfs: turning off barriers\n");
 468                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 469                         break;
 470                 case Opt_thread_pool:
 471                         intarg = 0;
 472                         match_int(&args[0], &intarg);
 473                         if (intarg)
 474                                 info->thread_pool_size = intarg;
 475                         break;
 476                 case Opt_max_inline:
 477                         num = match_strdup(&args[0]);
 478                         if (num) {
 479                                 info->max_inline = memparse(num, NULL);
 480                                 kfree(num);
 481
 482                                 if (info->max_inline) {
 483                                         info->max_inline = max_t(u64,
 484                                                 info->max_inline,
 485                                                 root->sectorsize);
 486                                 }
 487                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 488                                         (unsigned long long)info->max_inline);
 489                         }
 490                         break;
 491                 case Opt_alloc_start:
 492                         num = match_strdup(&args[0]);
 493                         if (num) {
 494                                 info->alloc_start = memparse(num, NULL);
 495                                 kfree(num);
 496                                 printk(KERN_INFO
 497                                         "btrfs: allocations start at %llu\n",
 498                                         (unsigned long long)info->alloc_start);
 499                         }
 500                         break;
 501                 case Opt_noacl:
 502                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 503                         break;
 504                 case Opt_notreelog:
 505                         printk(KERN_INFO "btrfs: disabling tree log\n");
 506                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 507                         break;
 508                 case Opt_flushoncommit:
 509                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 510                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 511                         break;
 512                 case Opt_ratio:
 513                         intarg = 0;
 514                         match_int(&args[0], &intarg);
 515                         if (intarg) {
 516                                 info->metadata_ratio = intarg;
 517                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 518                                        info->metadata_ratio);
 519                         }
 520                         break;
 521                 case Opt_discard:
 522                         btrfs_set_opt(info->mount_opt, DISCARD);
 523                         break;
 524                 case Opt_space_cache:
 525                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 526                         break;
 527                 case Opt_no_space_cache:
 528                         printk(KERN_INFO "btrfs: disabling disk space caching\n");
 529                         btrfs_clear_opt(info->mount_opt, SPACE_CACHE);
 530                         break;
 531                 case Opt_inode_cache:
 532                         printk(KERN_INFO "btrfs: enabling inode map caching\n");
 533                         btrfs_set_opt(info->mount_opt, INODE_MAP_CACHE);
 534                         break;
 535                 case Opt_clear_cache:
 536                         printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 537                         btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
 538                         break;
 539                 case Opt_user_subvol_rm_allowed:
 540                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 541                         break;
 542                 case Opt_enospc_debug:
 543                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 544                         break;
 545                 case Opt_defrag:
 546                         printk(KERN_INFO "btrfs: enabling auto defrag");
 547                         btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
 548                         break;
 549                 case Opt_recovery:
 550                         printk(KERN_INFO "btrfs: enabling auto recovery");
 551                         btrfs_set_opt(info->mount_opt, RECOVERY);
 552                         break;
 553                 case Opt_skip_balance:
 554                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 555                         break;
 556 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 557                 case Opt_check_integrity_including_extent_data:
 558                         printk(KERN_INFO "btrfs: enabling check integrity"
 559                                " including extent data\n");
 560                         btrfs_set_opt(info->mount_opt,
 561                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 562                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 563                         break;
 564                 case Opt_check_integrity:
 565                         printk(KERN_INFO "btrfs: enabling check integrity\n");
 566                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 567                         break;
 568                 case Opt_check_integrity_print_mask:
 569                         intarg = 0;
 570                         match_int(&args[0], &intarg);
 571                         if (intarg) {
 572                                 info->check_integrity_print_mask = intarg;
 573                                 printk(KERN_INFO "btrfs:"
 574                                        " check_integrity_print_mask 0x%x\n",
 575                                        info->check_integrity_print_mask);
 576                         }
 577                         break;
 578 #else
 579                 case Opt_check_integrity_including_extent_data:
 580                 case Opt_check_integrity:
 581                 case Opt_check_integrity_print_mask:
 582                         printk(KERN_ERR "btrfs: support for check_integrity*"
 583                                " not compiled in!\n");
 584                         ret = -EINVAL;
 585                         goto out;
 586 #endif
 587                 case Opt_fatal_errors:
 588                         if (strcmp(args[0].from, "panic") == 0)
 589                                 btrfs_set_opt(info->mount_opt,
 590                                               PANIC_ON_FATAL_ERROR);
 591                         else if (strcmp(args[0].from, "bug") == 0)
 592                                 btrfs_clear_opt(info->mount_opt,
 593                                               PANIC_ON_FATAL_ERROR);
 594                         else {
 595                                 ret = -EINVAL;
 596                                 goto out;
 597                         }
 598                         break;
 599                 case Opt_err:
 600                         printk(KERN_INFO "btrfs: unrecognized mount option "
 601                                "'%s'\n", p);
 602                         ret = -EINVAL;
 603                         goto out;
 604                 default:
 605                         break;
 606                 }
 607         }
 608 out:
 609         if (!ret && btrfs_test_opt(root, SPACE_CACHE))
 610                 printk(KERN_INFO "btrfs: disk space caching is enabled\n");
 611         kfree(orig);
 612         return ret;
 613 }
 614
 615 /*
 616  * Parse mount options that are required early in the mount process.
 617  *
 618  * All other options will be parsed on much later in the mount process and
 619  * only when we need to allocate a new super block.
 620  */
 621 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 622                 void *holder, char **subvol_name, u64 *subvol_objectid,
 623                 u64 *subvol_rootid, struct btrfs_fs_devices **fs_devices)
 624 {
 625         substring_t args[MAX_OPT_ARGS];
 626         char *device_name, *opts, *orig, *p;
 627         int error = 0;
 628         int intarg;
 629
 630         if (!options)
 631                 return 0;
 632
 633         /*
 634          * strsep changes the string, duplicate it because parse_options
 635          * gets called twice
 636          */
 637         opts = kstrdup(options, GFP_KERNEL);
 638         if (!opts)
 639                 return -ENOMEM;
 640         orig = opts;
 641
 642         while ((p = strsep(&opts, ",")) != NULL) {
 643                 int token;
 644                 if (!*p)
 645                         continue;
 646
 647                 token = match_token(p, tokens, args);
 648                 switch (token) {
 649                 case Opt_subvol:
 650                         kfree(*subvol_name);
 651                         *subvol_name = match_strdup(&args[0]);
 652                         break;
 653                 case Opt_subvolid:
 654                         intarg = 0;
 655                         error = match_int(&args[0], &intarg);
 656                         if (!error) {
 657                                 /* we want the original fs_tree */
 658                                 if (!intarg)
 659                                         *subvol_objectid =
 660                                                 BTRFS_FS_TREE_OBJECTID;
 661                                 else
 662                                         *subvol_objectid = intarg;
 663                         }
 664                         break;
 665                 case Opt_subvolrootid:
 666                         intarg = 0;
 667                         error = match_int(&args[0], &intarg);
 668                         if (!error) {
 669                                 /* we want the original fs_tree */
 670                                 if (!intarg)
 671                                         *subvol_rootid =
 672                                                 BTRFS_FS_TREE_OBJECTID;
 673                                 else
 674                                         *subvol_rootid = intarg;
 675                         }
 676                         break;
 677                 case Opt_device:
 678                         device_name = match_strdup(&args[0]);
 679                         if (!device_name) {
 680                                 error = -ENOMEM;
 681                                 goto out;
 682                         }
 683                         error = btrfs_scan_one_device(device_name,
 684                                         flags, holder, fs_devices);
 685                         kfree(device_name);
 686                         if (error)
 687                                 goto out;
 688                         break;
 689                 default:
 690                         break;
 691                 }
 692         }
 693
 694 out:
 695         kfree(orig);
 696         return error;
 697 }
 698
 699 static struct dentry *get_default_root(struct super_block *sb,
 700                                        u64 subvol_objectid)
 701 {
 702         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 703         struct btrfs_root *root = fs_info->tree_root;
 704         struct btrfs_root *new_root;
 705         struct btrfs_dir_item *di;
 706         struct btrfs_path *path;
 707         struct btrfs_key location;
 708         struct inode *inode;
 709         u64 dir_id;
 710         int new = 0;
 711
 712         /*
 713          * We have a specific subvol we want to mount, just setup location and
 714          * go look up the root.
 715          */
 716         if (subvol_objectid) {
 717                 location.objectid = subvol_objectid;
 718                 location.type = BTRFS_ROOT_ITEM_KEY;
 719                 location.offset = (u64)-1;
 720                 goto find_root;
 721         }
 722
 723         path = btrfs_alloc_path();
 724         if (!path)
 725                 return ERR_PTR(-ENOMEM);
 726         path->leave_spinning = 1;
 727
 728         /*
 729          * Find the "default" dir item which points to the root item that we
 730          * will mount by default if we haven't been given a specific subvolume
 731          * to mount.
 732          */
 733         dir_id = btrfs_super_root_dir(fs_info->super_copy);
 734         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 735         if (IS_ERR(di)) {
 736                 btrfs_free_path(path);
 737                 return ERR_CAST(di);
 738         }
 739         if (!di) {
 740                 /*
 741                  * Ok the default dir item isn't there.  This is weird since
 742                  * it's always been there, but don't freak out, just try and
 743                  * mount to root most subvolume.
 744                  */
 745                 btrfs_free_path(path);
 746                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
 747                 new_root = fs_info->fs_root;
 748                 goto setup_root;
 749         }
 750
 751         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 752         btrfs_free_path(path);
 753
 754 find_root:
 755         new_root = btrfs_read_fs_root_no_name(fs_info, &location);
 756         if (IS_ERR(new_root))
 757                 return ERR_CAST(new_root);
 758
 759         if (btrfs_root_refs(&new_root->root_item) == 0)
 760                 return ERR_PTR(-ENOENT);
 761
 762         dir_id = btrfs_root_dirid(&new_root->root_item);
 763 setup_root:
 764         location.objectid = dir_id;
 765         location.type = BTRFS_INODE_ITEM_KEY;
 766         location.offset = 0;
 767
 768         inode = btrfs_iget(sb, &location, new_root, &new);
 769         if (IS_ERR(inode))
 770                 return ERR_CAST(inode);
 771
 772         /*
 773          * If we're just mounting the root most subvol put the inode and return
 774          * a reference to the dentry.  We will have already gotten a reference
 775          * to the inode in btrfs_fill_super so we're good to go.
 776          */
 777         if (!new && sb->s_root->d_inode == inode) {
 778                 iput(inode);
 779                 return dget(sb->s_root);
 780         }
 781
 782         return d_obtain_alias(inode);
 783 }
 784
 785 static int btrfs_fill_super(struct super_block *sb,
 786                             struct btrfs_fs_devices *fs_devices,
 787                             void *data, int silent)
 788 {
 789         struct inode *inode;
 790         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 791         struct btrfs_key key;
 792         int err;
 793
 794         sb->s_maxbytes = MAX_LFS_FILESIZE;
 795         sb->s_magic = BTRFS_SUPER_MAGIC;
 796         sb->s_op = &btrfs_super_ops;
 797         sb->s_d_op = &btrfs_dentry_operations;
 798         sb->s_export_op = &btrfs_export_ops;
 799         sb->s_xattr = btrfs_xattr_handlers;
 800         sb->s_time_gran = 1;
 801 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 802         sb->s_flags |= MS_POSIXACL;
 803 #endif
 804         sb->s_flags |= MS_I_VERSION;
 805         err = open_ctree(sb, fs_devices, (char *)data);
 806         if (err) {
 807                 printk("btrfs: open_ctree failed\n");
 808                 return err;
 809         }
 810
 811         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 812         key.type = BTRFS_INODE_ITEM_KEY;
 813         key.offset = 0;
 814         inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
 815         if (IS_ERR(inode)) {
 816                 err = PTR_ERR(inode);
 817                 goto fail_close;
 818         }
 819
 820         sb->s_root = d_make_root(inode);
 821         if (!sb->s_root) {
 822                 err = -ENOMEM;
 823                 goto fail_close;
 824         }
 825
 826         save_mount_options(sb, data);
 827         cleancache_init_fs(sb);
 828         sb->s_flags |= MS_ACTIVE;
 829         return 0;
 830
 831 fail_close:
 832         close_ctree(fs_info->tree_root);
 833         return err;
 834 }
 835
 836 int btrfs_sync_fs(struct super_block *sb, int wait)
 837 {
 838         struct btrfs_trans_handle *trans;
 839         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 840         struct btrfs_root *root = fs_info->tree_root;
 841         int ret;
 842
 843         trace_btrfs_sync_fs(wait);
 844
 845         if (!wait) {
 846                 filemap_flush(fs_info->btree_inode->i_mapping);
 847                 return 0;
 848         }
 849
 850         btrfs_wait_ordered_extents(root, 0, 0);
 851
 852         trans = btrfs_start_transaction(root, 0);
 853         if (IS_ERR(trans))
 854                 return PTR_ERR(trans);
 855         ret = btrfs_commit_transaction(trans, root);
 856         return ret;
 857 }
 858
 859 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 860 {
 861         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
 862         struct btrfs_root *root = info->tree_root;
 863         char *compress_type;
 864
 865         if (btrfs_test_opt(root, DEGRADED))
 866                 seq_puts(seq, ",degraded");
 867         if (btrfs_test_opt(root, NODATASUM))
 868                 seq_puts(seq, ",nodatasum");
 869         if (btrfs_test_opt(root, NODATACOW))
 870                 seq_puts(seq, ",nodatacow");
 871         if (btrfs_test_opt(root, NOBARRIER))
 872                 seq_puts(seq, ",nobarrier");
 873         if (info->max_inline != 8192 * 1024)
 874                 seq_printf(seq, ",max_inline=%llu",
 875                            (unsigned long long)info->max_inline);
 876         if (info->alloc_start != 0)
 877                 seq_printf(seq, ",alloc_start=%llu",
 878                            (unsigned long long)info->alloc_start);
 879         if (info->thread_pool_size !=  min_t(unsigned long,
 880                                              num_online_cpus() + 2, 8))
 881                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 882         if (btrfs_test_opt(root, COMPRESS)) {
 883                 if (info->compress_type == BTRFS_COMPRESS_ZLIB)
 884                         compress_type = "zlib";
 885                 else
 886                         compress_type = "lzo";
 887                 if (btrfs_test_opt(root, FORCE_COMPRESS))
 888                         seq_printf(seq, ",compress-force=%s", compress_type);
 889                 else
 890                         seq_printf(seq, ",compress=%s", compress_type);
 891         }
 892         if (btrfs_test_opt(root, NOSSD))
 893                 seq_puts(seq, ",nossd");
 894         if (btrfs_test_opt(root, SSD_SPREAD))
 895                 seq_puts(seq, ",ssd_spread");
 896         else if (btrfs_test_opt(root, SSD))
 897                 seq_puts(seq, ",ssd");
 898         if (btrfs_test_opt(root, NOTREELOG))
 899                 seq_puts(seq, ",notreelog");
 900         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 901                 seq_puts(seq, ",flushoncommit");
 902         if (btrfs_test_opt(root, DISCARD))
 903                 seq_puts(seq, ",discard");
 904         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 905                 seq_puts(seq, ",noacl");
 906         if (btrfs_test_opt(root, SPACE_CACHE))
 907                 seq_puts(seq, ",space_cache");
 908         else
 909                 seq_puts(seq, ",nospace_cache");
 910         if (btrfs_test_opt(root, CLEAR_CACHE))
 911                 seq_puts(seq, ",clear_cache");
 912         if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
 913                 seq_puts(seq, ",user_subvol_rm_allowed");
 914         if (btrfs_test_opt(root, ENOSPC_DEBUG))
 915                 seq_puts(seq, ",enospc_debug");
 916         if (btrfs_test_opt(root, AUTO_DEFRAG))
 917                 seq_puts(seq, ",autodefrag");
 918         if (btrfs_test_opt(root, INODE_MAP_CACHE))
 919                 seq_puts(seq, ",inode_cache");
 920         if (btrfs_test_opt(root, SKIP_BALANCE))
 921                 seq_puts(seq, ",skip_balance");
 922         if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
 923                 seq_puts(seq, ",fatal_errors=panic");
 924         return 0;
 925 }
 926
 927 static int btrfs_test_super(struct super_block *s, void *data)
 928 {
 929         struct btrfs_fs_info *p = data;
 930         struct btrfs_fs_info *fs_info = btrfs_sb(s);
 931
 932         return fs_info->fs_devices == p->fs_devices;
 933 }
 934
 935 static int btrfs_set_super(struct super_block *s, void *data)
 936 {
 937         int err = set_anon_super(s, data);
 938         if (!err)
 939                 s->s_fs_info = data;
 940         return err;
 941 }
 942
 943 /*
 944  * subvolumes are identified by ino 256
 945  */
 946 static inline int is_subvolume_inode(struct inode *inode)
 947 {
 948         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
 949                 return 1;
 950         return 0;
 951 }
 952
 953 /*
 954  * This will strip out the subvol=%s argument for an argument string and add
 955  * subvolid=0 to make sure we get the actual tree root for path walking to the
 956  * subvol we want.
 957  */
 958 static char *setup_root_args(char *args)
 959 {
 960         unsigned len = strlen(args) + 2 + 1;
 961         char *src, *dst, *buf;
 962
 963         /*
 964          * We need the same args as before, but with this substitution:
 965          * s!subvol=[^,]+!subvolid=0!
 966          *
 967          * Since the replacement string is up to 2 bytes longer than the
 968          * original, allocate strlen(args) + 2 + 1 bytes.
 969          */
 970
 971         src = strstr(args, "subvol=");
 972         /* This shouldn't happen, but just in case.. */
 973         if (!src)
 974                 return NULL;
 975
 976         buf = dst = kmalloc(len, GFP_NOFS);
 977         if (!buf)
 978                 return NULL;
 979
 980         /*
 981          * If the subvol= arg is not at the start of the string,
 982          * copy whatever precedes it into buf.
 983          */
 984         if (src != args) {
 985                 *src++ = '\0';
 986                 strcpy(buf, args);
 987                 dst += strlen(args);
 988         }
 989
 990         strcpy(dst, "subvolid=0");
 991         dst += strlen("subvolid=0");
 992
 993         /*
 994          * If there is a "," after the original subvol=... string,
 995          * copy that suffix into our buffer.  Otherwise, we're done.
 996          */
 997         src = strchr(src, ',');
 998         if (src)
 999                 strcpy(dst, src);
1000
1001         return buf;
1002 }
1003
1004 static struct dentry *mount_subvol(const char *subvol_name, int flags,
1005                                    const char *device_name, char *data)
1006 {
1007         struct dentry *root;
1008         struct vfsmount *mnt;
1009         char *newargs;
1010
1011         newargs = setup_root_args(data);
1012         if (!newargs)
1013                 return ERR_PTR(-ENOMEM);
1014         mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
1015                              newargs);
1016         kfree(newargs);
1017         if (IS_ERR(mnt))
1018                 return ERR_CAST(mnt);
1019
1020         root = mount_subtree(mnt, subvol_name);
1021
1022         if (!IS_ERR(root) && !is_subvolume_inode(root->d_inode)) {
1023                 struct super_block *s = root->d_sb;
1024                 dput(root);
1025                 root = ERR_PTR(-EINVAL);
1026                 deactivate_locked_super(s);
1027                 printk(KERN_ERR "btrfs: '%s' is not a valid subvolume\n",
1028                                 subvol_name);
1029         }
1030
1031         return root;
1032 }
1033
1034 /*
1035  * Find a superblock for the given device / mount point.
1036  *
1037  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
1038  *        for multiple device setup.  Make sure to keep it in sync.
1039  */
1040 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1041                 const char *device_name, void *data)
1042 {
1043         struct block_device *bdev = NULL;
1044         struct super_block *s;
1045         struct dentry *root;
1046         struct btrfs_fs_devices *fs_devices = NULL;
1047         struct btrfs_fs_info *fs_info = NULL;
1048         fmode_t mode = FMODE_READ;
1049         char *subvol_name = NULL;
1050         u64 subvol_objectid = 0;
1051         u64 subvol_rootid = 0;
1052         int error = 0;
1053
1054         if (!(flags & MS_RDONLY))
1055                 mode |= FMODE_WRITE;
1056
1057         error = btrfs_parse_early_options(data, mode, fs_type,
1058                                           &subvol_name, &subvol_objectid,
1059                                           &subvol_rootid, &fs_devices);
1060         if (error) {
1061                 kfree(subvol_name);
1062                 return ERR_PTR(error);
1063         }
1064
1065         if (subvol_name) {
1066                 root = mount_subvol(subvol_name, flags, device_name, data);
1067                 kfree(subvol_name);
1068                 return root;
1069         }
1070
1071         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1072         if (error)
1073                 return ERR_PTR(error);
1074
1075         /*
1076          * Setup a dummy root and fs_info for test/set super.  This is because
1077          * we don't actually fill this stuff out until open_ctree, but we need
1078          * it for searching for existing supers, so this lets us do that and
1079          * then open_ctree will properly initialize everything later.
1080          */
1081         fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
1082         if (!fs_info)
1083                 return ERR_PTR(-ENOMEM);
1084
1085         fs_info->fs_devices = fs_devices;
1086
1087         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1088         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1089         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1090                 error = -ENOMEM;
1091                 goto error_fs_info;
1092         }
1093
1094         error = btrfs_open_devices(fs_devices, mode, fs_type);
1095         if (error)
1096                 goto error_fs_info;
1097
1098         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
1099                 error = -EACCES;
1100                 goto error_close_devices;
1101         }
1102
1103         bdev = fs_devices->latest_bdev;
1104         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | MS_NOSEC,
1105                  fs_info);
1106         if (IS_ERR(s)) {
1107                 error = PTR_ERR(s);
1108                 goto error_close_devices;
1109         }
1110
1111         if (s->s_root) {
1112                 btrfs_close_devices(fs_devices);
1113                 free_fs_info(fs_info);
1114                 if ((flags ^ s->s_flags) & MS_RDONLY)
1115                         error = -EBUSY;
1116         } else {
1117                 char b[BDEVNAME_SIZE];
1118
1119                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
1120                 btrfs_sb(s)->bdev_holder = fs_type;
1121                 error = btrfs_fill_super(s, fs_devices, data,
1122                                          flags & MS_SILENT ? 1 : 0);
1123         }
1124
1125         root = !error ? get_default_root(s, subvol_objectid) : ERR_PTR(error);
1126         if (IS_ERR(root))
1127                 deactivate_locked_super(s);
1128
1129         return root;
1130
1131 error_close_devices:
1132         btrfs_close_devices(fs_devices);
1133 error_fs_info:
1134         free_fs_info(fs_info);
1135         return ERR_PTR(error);
1136 }
1137
1138 static void btrfs_set_max_workers(struct btrfs_workers *workers, int new_limit)
1139 {
1140         spin_lock_irq(&workers->lock);
1141         workers->max_workers = new_limit;
1142         spin_unlock_irq(&workers->lock);
1143 }
1144
1145 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1146                                      int new_pool_size, int old_pool_size)
1147 {
1148         if (new_pool_size == old_pool_size)
1149                 return;
1150
1151         fs_info->thread_pool_size = new_pool_size;
1152
1153         printk(KERN_INFO "btrfs: resize thread pool %d -> %d\n",
1154                old_pool_size, new_pool_size);
1155
1156         btrfs_set_max_workers(&fs_info->generic_worker, new_pool_size);
1157         btrfs_set_max_workers(&fs_info->workers, new_pool_size);
1158         btrfs_set_max_workers(&fs_info->delalloc_workers, new_pool_size);
1159         btrfs_set_max_workers(&fs_info->submit_workers, new_pool_size);
1160         btrfs_set_max_workers(&fs_info->caching_workers, new_pool_size);
1161         btrfs_set_max_workers(&fs_info->fixup_workers, new_pool_size);
1162         btrfs_set_max_workers(&fs_info->endio_workers, new_pool_size);
1163         btrfs_set_max_workers(&fs_info->endio_meta_workers, new_pool_size);
1164         btrfs_set_max_workers(&fs_info->endio_meta_write_workers, new_pool_size);
1165         btrfs_set_max_workers(&fs_info->endio_write_workers, new_pool_size);
1166         btrfs_set_max_workers(&fs_info->endio_freespace_worker, new_pool_size);
1167         btrfs_set_max_workers(&fs_info->delayed_workers, new_pool_size);
1168         btrfs_set_max_workers(&fs_info->readahead_workers, new_pool_size);
1169         btrfs_set_max_workers(&fs_info->scrub_workers, new_pool_size);
1170 }
1171
1172 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1173 {
1174         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1175         struct btrfs_root *root = fs_info->tree_root;
1176         unsigned old_flags = sb->s_flags;
1177         unsigned long old_opts = fs_info->mount_opt;
1178         unsigned long old_compress_type = fs_info->compress_type;
1179         u64 old_max_inline = fs_info->max_inline;
1180         u64 old_alloc_start = fs_info->alloc_start;
1181         int old_thread_pool_size = fs_info->thread_pool_size;
1182         unsigned int old_metadata_ratio = fs_info->metadata_ratio;
1183         int ret;
1184
1185         ret = btrfs_parse_options(root, data);
1186         if (ret) {
1187                 ret = -EINVAL;
1188                 goto restore;
1189         }
1190
1191         btrfs_resize_thread_pool(fs_info,
1192                 fs_info->thread_pool_size, old_thread_pool_size);
1193
1194         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1195                 return 0;
1196
1197         if (*flags & MS_RDONLY) {
1198                 sb->s_flags |= MS_RDONLY;
1199
1200                 ret = btrfs_commit_super(root);
1201                 if (ret)
1202                         goto restore;
1203         } else {
1204                 if (fs_info->fs_devices->rw_devices == 0) {
1205                         ret = -EACCES;
1206                         goto restore;
1207                 }
1208
1209                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1210                         ret = -EINVAL;
1211                         goto restore;
1212                 }
1213
1214                 ret = btrfs_cleanup_fs_roots(fs_info);
1215                 if (ret)
1216                         goto restore;
1217
1218                 /* recover relocation */
1219                 ret = btrfs_recover_relocation(root);
1220                 if (ret)
1221                         goto restore;
1222
1223                 ret = btrfs_resume_balance_async(fs_info);
1224                 if (ret)
1225                         goto restore;
1226
1227                 sb->s_flags &= ~MS_RDONLY;
1228         }
1229
1230         return 0;
1231
1232 restore:
1233         /* We've hit an error - don't reset MS_RDONLY */
1234         if (sb->s_flags & MS_RDONLY)
1235                 old_flags |= MS_RDONLY;
1236         sb->s_flags = old_flags;
1237         fs_info->mount_opt = old_opts;
1238         fs_info->compress_type = old_compress_type;
1239         fs_info->max_inline = old_max_inline;
1240         fs_info->alloc_start = old_alloc_start;
1241         btrfs_resize_thread_pool(fs_info,
1242                 old_thread_pool_size, fs_info->thread_pool_size);
1243         fs_info->metadata_ratio = old_metadata_ratio;
1244         return ret;
1245 }
1246
1247 /* Used to sort the devices by max_avail(descending sort) */
1248 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1249                                        const void *dev_info2)
1250 {
1251         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1252             ((struct btrfs_device_info *)dev_info2)->max_avail)
1253                 return -1;
1254         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1255                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1256                 return 1;
1257         else
1258         return 0;
1259 }
1260
1261 /*
1262  * sort the devices by max_avail, in which max free extent size of each device
1263  * is stored.(Descending Sort)
1264  */
1265 static inline void btrfs_descending_sort_devices(
1266                                         struct btrfs_device_info *devices,
1267                                         size_t nr_devices)
1268 {
1269         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1270              btrfs_cmp_device_free_bytes, NULL);
1271 }
1272
1273 /*
1274  * The helper to calc the free space on the devices that can be used to store
1275  * file data.
1276  */
1277 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
1278 {
1279         struct btrfs_fs_info *fs_info = root->fs_info;
1280         struct btrfs_device_info *devices_info;
1281         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1282         struct btrfs_device *device;
1283         u64 skip_space;
1284         u64 type;
1285         u64 avail_space;
1286         u64 used_space;
1287         u64 min_stripe_size;
1288         int min_stripes = 1, num_stripes = 1;
1289         int i = 0, nr_devices;
1290         int ret;
1291
1292         nr_devices = fs_info->fs_devices->open_devices;
1293         BUG_ON(!nr_devices);
1294
1295         devices_info = kmalloc(sizeof(*devices_info) * nr_devices,
1296                                GFP_NOFS);
1297         if (!devices_info)
1298                 return -ENOMEM;
1299
1300         /* calc min stripe number for data space alloction */
1301         type = btrfs_get_alloc_profile(root, 1);
1302         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1303                 min_stripes = 2;
1304                 num_stripes = nr_devices;
1305         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1306                 min_stripes = 2;
1307                 num_stripes = 2;
1308         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1309                 min_stripes = 4;
1310                 num_stripes = 4;
1311         }
1312
1313         if (type & BTRFS_BLOCK_GROUP_DUP)
1314                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1315         else
1316                 min_stripe_size = BTRFS_STRIPE_LEN;
1317
1318         list_for_each_entry(device, &fs_devices->devices, dev_list) {
1319                 if (!device->in_fs_metadata || !device->bdev)
1320                         continue;
1321
1322                 avail_space = device->total_bytes - device->bytes_used;
1323
1324                 /* align with stripe_len */
1325                 do_div(avail_space, BTRFS_STRIPE_LEN);
1326                 avail_space *= BTRFS_STRIPE_LEN;
1327
1328                 /*
1329                  * In order to avoid overwritting the superblock on the drive,
1330                  * btrfs starts at an offset of at least 1MB when doing chunk
1331                  * allocation.
1332                  */
1333                 skip_space = 1024 * 1024;
1334
1335                 /* user can set the offset in fs_info->alloc_start. */
1336                 if (fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1337                     device->total_bytes)
1338                         skip_space = max(fs_info->alloc_start, skip_space);
1339
1340                 /*
1341                  * btrfs can not use the free space in [0, skip_space - 1],
1342                  * we must subtract it from the total. In order to implement
1343                  * it, we account the used space in this range first.
1344                  */
1345                 ret = btrfs_account_dev_extents_size(device, 0, skip_space - 1,
1346                                                      &used_space);
1347                 if (ret) {
1348                         kfree(devices_info);
1349                         return ret;
1350                 }
1351
1352                 /* calc the free space in [0, skip_space - 1] */
1353                 skip_space -= used_space;
1354
1355                 /*
1356                  * we can use the free space in [0, skip_space - 1], subtract
1357                  * it from the total.
1358                  */
1359                 if (avail_space && avail_space >= skip_space)
1360                         avail_space -= skip_space;
1361                 else
1362                         avail_space = 0;
1363
1364                 if (avail_space < min_stripe_size)
1365                         continue;
1366
1367                 devices_info[i].dev = device;
1368                 devices_info[i].max_avail = avail_space;
1369
1370                 i++;
1371         }
1372
1373         nr_devices = i;
1374
1375         btrfs_descending_sort_devices(devices_info, nr_devices);
1376
1377         i = nr_devices - 1;
1378         avail_space = 0;
1379         while (nr_devices >= min_stripes) {
1380                 if (num_stripes > nr_devices)
1381                         num_stripes = nr_devices;
1382
1383                 if (devices_info[i].max_avail >= min_stripe_size) {
1384                         int j;
1385                         u64 alloc_size;
1386
1387                         avail_space += devices_info[i].max_avail * num_stripes;
1388                         alloc_size = devices_info[i].max_avail;
1389                         for (j = i + 1 - num_stripes; j <= i; j++)
1390                                 devices_info[j].max_avail -= alloc_size;
1391                 }
1392                 i--;
1393                 nr_devices--;
1394         }
1395
1396         kfree(devices_info);
1397         *free_bytes = avail_space;
1398         return 0;
1399 }
1400
1401 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1402 {
1403         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
1404         struct btrfs_super_block *disk_super = fs_info->super_copy;
1405         struct list_head *head = &fs_info->space_info;
1406         struct btrfs_space_info *found;
1407         u64 total_used = 0;
1408         u64 total_free_data = 0;
1409         int bits = dentry->d_sb->s_blocksize_bits;
1410         __be32 *fsid = (__be32 *)fs_info->fsid;
1411         int ret;
1412
1413         /* holding chunk_muext to avoid allocating new chunks */
1414         mutex_lock(&fs_info->chunk_mutex);
1415         rcu_read_lock();
1416         list_for_each_entry_rcu(found, head, list) {
1417                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
1418                         total_free_data += found->disk_total - found->disk_used;
1419                         total_free_data -=
1420                                 btrfs_account_ro_block_groups_free_space(found);
1421                 }
1422
1423                 total_used += found->disk_used;
1424         }
1425         rcu_read_unlock();
1426
1427         buf->f_namelen = BTRFS_NAME_LEN;
1428         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
1429         buf->f_bfree = buf->f_blocks - (total_used >> bits);
1430         buf->f_bsize = dentry->d_sb->s_blocksize;
1431         buf->f_type = BTRFS_SUPER_MAGIC;
1432         buf->f_bavail = total_free_data;
1433         ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
1434         if (ret) {
1435                 mutex_unlock(&fs_info->chunk_mutex);
1436                 return ret;
1437         }
1438         buf->f_bavail += total_free_data;
1439         buf->f_bavail = buf->f_bavail >> bits;
1440         mutex_unlock(&fs_info->chunk_mutex);
1441
1442         /* We treat it as constant endianness (it doesn't matter _which_)
1443            because we want the fsid to come out the same whether mounted
1444            on a big-endian or little-endian host */
1445         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
1446         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
1447         /* Mask in the root object ID too, to disambiguate subvols */
1448         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
1449         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
1450
1451         return 0;
1452 }
1453
1454 static void btrfs_kill_super(struct super_block *sb)
1455 {
1456         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1457         kill_anon_super(sb);
1458         free_fs_info(fs_info);
1459 }
1460
1461 static struct file_system_type btrfs_fs_type = {
1462         .owner          = THIS_MODULE,
1463         .name           = "btrfs",
1464         .mount          = btrfs_mount,
1465         .kill_sb        = btrfs_kill_super,
1466         .fs_flags       = FS_REQUIRES_DEV,
1467 };
1468
1469 /*
1470  * used by btrfsctl to scan devices when no FS is mounted
1471  */
1472 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
1473                                 unsigned long arg)
1474 {
1475         struct btrfs_ioctl_vol_args *vol;
1476         struct btrfs_fs_devices *fs_devices;
1477         int ret = -ENOTTY;
1478
1479         if (!capable(CAP_SYS_ADMIN))
1480                 return -EPERM;
1481
1482         vol = memdup_user((void __user *)arg, sizeof(*vol));
1483         if (IS_ERR(vol))
1484                 return PTR_ERR(vol);
1485
1486         switch (cmd) {
1487         case BTRFS_IOC_SCAN_DEV:
1488                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1489                                             &btrfs_fs_type, &fs_devices);
1490                 break;
1491         case BTRFS_IOC_DEVICES_READY:
1492                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1493                                             &btrfs_fs_type, &fs_devices);
1494                 if (ret)
1495                         break;
1496                 ret = !(fs_devices->num_devices == fs_devices->total_devices);
1497                 break;
1498         }
1499
1500         kfree(vol);
1501         return ret;
1502 }
1503
1504 static int btrfs_freeze(struct super_block *sb)
1505 {
1506         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1507         mutex_lock(&fs_info->transaction_kthread_mutex);
1508         mutex_lock(&fs_info->cleaner_mutex);
1509         return 0;
1510 }
1511
1512 static int btrfs_unfreeze(struct super_block *sb)
1513 {
1514         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1515         mutex_unlock(&fs_info->cleaner_mutex);
1516         mutex_unlock(&fs_info->transaction_kthread_mutex);
1517         return 0;
1518 }
1519
1520 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
1521 {
1522         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
1523         struct btrfs_fs_devices *cur_devices;
1524         struct btrfs_device *dev, *first_dev = NULL;
1525         struct list_head *head;
1526         struct rcu_string *name;
1527
1528         mutex_lock(&fs_info->fs_devices->device_list_mutex);
1529         cur_devices = fs_info->fs_devices;
1530         while (cur_devices) {
1531                 head = &cur_devices->devices;
1532                 list_for_each_entry(dev, head, dev_list) {
1533                         if (!first_dev || dev->devid < first_dev->devid)
1534                                 first_dev = dev;
1535                 }
1536                 cur_devices = cur_devices->seed;
1537         }
1538
1539         if (first_dev) {
1540                 rcu_read_lock();
1541                 name = rcu_dereference(first_dev->name);
1542                 seq_escape(m, name->str, " \t\n\\");
1543                 rcu_read_unlock();
1544         } else {
1545                 WARN_ON(1);
1546         }
1547         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1548         return 0;
1549 }
1550
1551 static const struct super_operations btrfs_super_ops = {
1552         .drop_inode     = btrfs_drop_inode,
1553         .evict_inode    = btrfs_evict_inode,
1554         .put_super      = btrfs_put_super,
1555         .sync_fs        = btrfs_sync_fs,
1556         .show_options   = btrfs_show_options,
1557         .show_devname   = btrfs_show_devname,
1558         .write_inode    = btrfs_write_inode,
1559         .alloc_inode    = btrfs_alloc_inode,
1560         .destroy_inode  = btrfs_destroy_inode,
1561         .statfs         = btrfs_statfs,
1562         .remount_fs     = btrfs_remount,
1563         .freeze_fs      = btrfs_freeze,
1564         .unfreeze_fs    = btrfs_unfreeze,
1565 };
1566
1567 static const struct file_operations btrfs_ctl_fops = {
1568         .unlocked_ioctl  = btrfs_control_ioctl,
1569         .compat_ioctl = btrfs_control_ioctl,
1570         .owner   = THIS_MODULE,
1571         .llseek = noop_llseek,
1572 };
1573
1574 static struct miscdevice btrfs_misc = {
1575         .minor          = BTRFS_MINOR,
1576         .name           = "btrfs-control",
1577         .fops           = &btrfs_ctl_fops
1578 };
1579
1580 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
1581 MODULE_ALIAS("devname:btrfs-control");
1582
1583 static int btrfs_interface_init(void)
1584 {
1585         return misc_register(&btrfs_misc);
1586 }
1587
1588 static void btrfs_interface_exit(void)
1589 {
1590         if (misc_deregister(&btrfs_misc) < 0)
1591                 printk(KERN_INFO "misc_deregister failed for control device");
1592 }
1593
1594 static int __init init_btrfs_fs(void)
1595 {
1596         int err;
1597
1598         err = btrfs_init_sysfs();
1599         if (err)
1600                 return err;
1601
1602         btrfs_init_compress();
1603
1604         err = btrfs_init_cachep();
1605         if (err)
1606                 goto free_compress;
1607
1608         err = extent_io_init();
1609         if (err)
1610                 goto free_cachep;
1611
1612         err = extent_map_init();
1613         if (err)
1614                 goto free_extent_io;
1615
1616         err = btrfs_delayed_inode_init();
1617         if (err)
1618                 goto free_extent_map;
1619
1620         err = btrfs_interface_init();
1621         if (err)
1622                 goto free_delayed_inode;
1623
1624         err = register_filesystem(&btrfs_fs_type);
1625         if (err)
1626                 goto unregister_ioctl;
1627
1628         btrfs_init_lockdep();
1629
1630         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
1631         return 0;
1632
1633 unregister_ioctl:
1634         btrfs_interface_exit();
1635 free_delayed_inode:
1636         btrfs_delayed_inode_exit();
1637 free_extent_map:
1638         extent_map_exit();
1639 free_extent_io:
1640         extent_io_exit();
1641 free_cachep:
1642         btrfs_destroy_cachep();
1643 free_compress:
1644         btrfs_exit_compress();
1645         btrfs_exit_sysfs();
1646         return err;
1647 }
1648
1649 static void __exit exit_btrfs_fs(void)
1650 {
1651         btrfs_destroy_cachep();
1652         btrfs_delayed_inode_exit();
1653         extent_map_exit();
1654         extent_io_exit();
1655         btrfs_interface_exit();
1656         unregister_filesystem(&btrfs_fs_type);
1657         btrfs_exit_sysfs();
1658         btrfs_cleanup_fs_uuids();
1659         btrfs_exit_compress();
1660 }
1661
1662 module_init(init_btrfs_fs)
1663 module_exit(exit_btrfs_fs)
1664
1665 MODULE_LICENSE("GPL");