linux/fs/btrfs/super.c
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   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
  62static const struct super_operations btrfs_super_ops;
  63static struct file_system_type btrfs_fs_type;
  64
  65static 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
  94static 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
 103static 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 */
 109static 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 */
 129void __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
 167static const char * const logtypes[] = {
 168        "emergency",
 169        "alert",
 170        "critical",
 171        "error",
 172        "warning",
 173        "notice",
 174        "info",
 175        "debug",
 176};
 177
 178void 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
 209void __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 */
 242void __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\n");
 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                char nbuf[16];
 252                const char *errstr;
 253
 254                errstr = btrfs_decode_error(root->fs_info, errno, nbuf);
 255                btrfs_printk(root->fs_info,
 256                             "%s:%d: Aborting unused transaction(%s).\n",
 257                             function, line, errstr);
 258                return;
 259        }
 260        trans->transaction->aborted = errno;
 261        __btrfs_std_error(root->fs_info, function, line, errno, NULL);
 262}
 263/*
 264 * __btrfs_panic decodes unexpected, fatal errors from the caller,
 265 * issues an alert, and either panics or BUGs, depending on mount options.
 266 */
 267void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
 268                   unsigned int line, int errno, const char *fmt, ...)
 269{
 270        char nbuf[16];
 271        char *s_id = "<unknown>";
 272        const char *errstr;
 273        struct va_format vaf = { .fmt = fmt };
 274        va_list args;
 275
 276        if (fs_info)
 277                s_id = fs_info->sb->s_id;
 278
 279        va_start(args, fmt);
 280        vaf.va = &args;
 281
 282        errstr = btrfs_decode_error(fs_info, errno, nbuf);
 283        if (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR)
 284                panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (%s)\n",
 285                        s_id, function, line, &vaf, errstr);
 286
 287        printk(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (%s)\n",
 288               s_id, function, line, &vaf, errstr);
 289        va_end(args);
 290        /* Caller calls BUG() */
 291}
 292
 293static void btrfs_put_super(struct super_block *sb)
 294{
 295        (void)close_ctree(btrfs_sb(sb)->tree_root);
 296        /* FIXME: need to fix VFS to return error? */
 297        /* AV: return it _where_?  ->put_super() can be triggered by any number
 298         * of async events, up to and including delivery of SIGKILL to the
 299         * last process that kept it busy.  Or segfault in the aforementioned
 300         * process...  Whom would you report that to?
 301         */
 302}
 303
 304enum {
 305        Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 306        Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 307        Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 308        Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 309        Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 310        Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
 311        Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
 312        Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
 313        Opt_check_integrity, Opt_check_integrity_including_extent_data,
 314        Opt_check_integrity_print_mask, Opt_fatal_errors,
 315        Opt_err,
 316};
 317
 318static match_table_t tokens = {
 319        {Opt_degraded, "degraded"},
 320        {Opt_subvol, "subvol=%s"},
 321        {Opt_subvolid, "subvolid=%d"},
 322        {Opt_device, "device=%s"},
 323        {Opt_nodatasum, "nodatasum"},
 324        {Opt_nodatacow, "nodatacow"},
 325        {Opt_nobarrier, "nobarrier"},
 326        {Opt_max_inline, "max_inline=%s"},
 327        {Opt_alloc_start, "alloc_start=%s"},
 328        {Opt_thread_pool, "thread_pool=%d"},
 329        {Opt_compress, "compress"},
 330        {Opt_compress_type, "compress=%s"},
 331        {Opt_compress_force, "compress-force"},
 332        {Opt_compress_force_type, "compress-force=%s"},
 333        {Opt_ssd, "ssd"},
 334        {Opt_ssd_spread, "ssd_spread"},
 335        {Opt_nossd, "nossd"},
 336        {Opt_noacl, "noacl"},
 337        {Opt_notreelog, "notreelog"},
 338        {Opt_flushoncommit, "flushoncommit"},
 339        {Opt_ratio, "metadata_ratio=%d"},
 340        {Opt_discard, "discard"},
 341        {Opt_space_cache, "space_cache"},
 342        {Opt_clear_cache, "clear_cache"},
 343        {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 344        {Opt_enospc_debug, "enospc_debug"},
 345        {Opt_subvolrootid, "subvolrootid=%d"},
 346        {Opt_defrag, "autodefrag"},
 347        {Opt_inode_cache, "inode_cache"},
 348        {Opt_no_space_cache, "nospace_cache"},
 349        {Opt_recovery, "recovery"},
 350        {Opt_skip_balance, "skip_balance"},
 351        {Opt_check_integrity, "check_int"},
 352        {Opt_check_integrity_including_extent_data, "check_int_data"},
 353        {Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
 354        {Opt_fatal_errors, "fatal_errors=%s"},
 355        {Opt_err, NULL},
 356};
 357
 358/*
 359 * Regular mount options parser.  Everything that is needed only when
 360 * reading in a new superblock is parsed here.
 361 * XXX JDM: This needs to be cleaned up for remount.
 362 */
 363int btrfs_parse_options(struct btrfs_root *root, char *options)
 364{
 365        struct btrfs_fs_info *info = root->fs_info;
 366        substring_t args[MAX_OPT_ARGS];
 367        char *p, *num, *orig = NULL;
 368        u64 cache_gen;
 369        int intarg;
 370        int ret = 0;
 371        char *compress_type;
 372        bool compress_force = false;
 373
 374        cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
 375        if (cache_gen)
 376                btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 377
 378        if (!options)
 379                goto out;
 380
 381        /*
 382         * strsep changes the string, duplicate it because parse_options
 383         * gets called twice
 384         */
 385        options = kstrdup(options, GFP_NOFS);
 386        if (!options)
 387                return -ENOMEM;
 388
 389        orig = options;
 390
 391        while ((p = strsep(&options, ",")) != NULL) {
 392                int token;
 393                if (!*p)
 394                        continue;
 395
 396                token = match_token(p, tokens, args);
 397                switch (token) {
 398                case Opt_degraded:
 399                        printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 400                        btrfs_set_opt(info->mount_opt, DEGRADED);
 401                        break;
 402                case Opt_subvol:
 403                case Opt_subvolid:
 404                case Opt_subvolrootid:
 405                case Opt_device:
 406                        /*
 407                         * These are parsed by btrfs_parse_early_options
 408                         * and can be happily ignored here.
 409                         */
 410                        break;
 411                case Opt_nodatasum:
 412                        printk(KERN_INFO "btrfs: setting nodatasum\n");
 413                        btrfs_set_opt(info->mount_opt, NODATASUM);
 414                        break;
 415                case Opt_nodatacow:
 416                        if (!btrfs_test_opt(root, COMPRESS) ||
 417                                !btrfs_test_opt(root, FORCE_COMPRESS)) {
 418                                        printk(KERN_INFO "btrfs: setting nodatacow, compression disabled\n");
 419                        } else {
 420                                printk(KERN_INFO "btrfs: setting nodatacow\n");
 421                        }
 422                        info->compress_type = BTRFS_COMPRESS_NONE;
 423                        btrfs_clear_opt(info->mount_opt, COMPRESS);
 424                        btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 425                        btrfs_set_opt(info->mount_opt, NODATACOW);
 426                        btrfs_set_opt(info->mount_opt, NODATASUM);
 427                        break;
 428                case Opt_compress_force:
 429                case Opt_compress_force_type:
 430                        compress_force = true;
 431                case Opt_compress:
 432                case Opt_compress_type:
 433                        if (token == Opt_compress ||
 434                            token == Opt_compress_force ||
 435                            strcmp(args[0].from, "zlib") == 0) {
 436                                compress_type = "zlib";
 437                                info->compress_type = BTRFS_COMPRESS_ZLIB;
 438                                btrfs_set_opt(info->mount_opt, COMPRESS);
 439                                btrfs_clear_opt(info->mount_opt, NODATACOW);
 440                                btrfs_clear_opt(info->mount_opt, NODATASUM);
 441                        } else if (strcmp(args[0].from, "lzo") == 0) {
 442                                compress_type = "lzo";
 443                                info->compress_type = BTRFS_COMPRESS_LZO;
 444                                btrfs_set_opt(info->mount_opt, COMPRESS);
 445                                btrfs_clear_opt(info->mount_opt, NODATACOW);
 446                                btrfs_clear_opt(info->mount_opt, NODATASUM);
 447                                btrfs_set_fs_incompat(info, COMPRESS_LZO);
 448                        } else if (strncmp(args[0].from, "no", 2) == 0) {
 449                                compress_type = "no";
 450                                info->compress_type = BTRFS_COMPRESS_NONE;
 451                                btrfs_clear_opt(info->mount_opt, COMPRESS);
 452                                btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
 453                                compress_force = false;
 454                        } else {
 455                                ret = -EINVAL;
 456                                goto out;
 457                        }
 458
 459                        if (compress_force) {
 460                                btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 461                                pr_info("btrfs: force %s compression\n",
 462                                        compress_type);
 463                        } else
 464                                pr_info("btrfs: use %s compression\n",
 465                                        compress_type);
 466                        break;
 467                case Opt_ssd:
 468                        printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 469                        btrfs_set_opt(info->mount_opt, SSD);
 470                        break;
 471                case Opt_ssd_spread:
 472                        printk(KERN_INFO "btrfs: use spread ssd "
 473                               "allocation scheme\n");
 474                        btrfs_set_opt(info->mount_opt, SSD);
 475                        btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 476                        break;
 477                case Opt_nossd:
 478                        printk(KERN_INFO "btrfs: not using ssd allocation "
 479                               "scheme\n");
 480                        btrfs_set_opt(info->mount_opt, NOSSD);
 481                        btrfs_clear_opt(info->mount_opt, SSD);
 482                        btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 483                        break;
 484                case Opt_nobarrier:
 485                        printk(KERN_INFO "btrfs: turning off barriers\n");
 486                        btrfs_set_opt(info->mount_opt, NOBARRIER);
 487                        break;
 488                case Opt_thread_pool:
 489                        intarg = 0;
 490                        match_int(&args[0], &intarg);
 491                        if (intarg)
 492                                info->thread_pool_size = intarg;
 493                        break;
 494                case Opt_max_inline:
 495                        num = match_strdup(&args[0]);
 496                        if (num) {
 497                                info->max_inline = memparse(num, NULL);
 498                                kfree(num);
 499
 500                                if (info->max_inline) {
 501                                        info->max_inline = max_t(u64,
 502                                                info->max_inline,
 503                                                root->sectorsize);
 504                                }
 505                                printk(KERN_INFO "btrfs: max_inline at %llu\n",
 506                                        (unsigned long long)info->max_inline);
 507                        }
 508                        break;
 509                case Opt_alloc_start:
 510                        num = match_strdup(&args[0]);
 511                        if (num) {
 512                                info->alloc_start = memparse(num, NULL);
 513                                kfree(num);
 514                                printk(KERN_INFO
 515                                        "btrfs: allocations start at %llu\n",
 516                                        (unsigned long long)info->alloc_start);
 517                        }
 518                        break;
 519                case Opt_noacl:
 520                        root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 521                        break;
 522                case Opt_notreelog:
 523                        printk(KERN_INFO "btrfs: disabling tree log\n");
 524                        btrfs_set_opt(info->mount_opt, NOTREELOG);
 525                        break;
 526                case Opt_flushoncommit:
 527                        printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 528                        btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 529                        break;
 530                case Opt_ratio:
 531                        intarg = 0;
 532                        match_int(&args[0], &intarg);
 533                        if (intarg) {
 534                                info->metadata_ratio = intarg;
 535                                printk(KERN_INFO "btrfs: metadata ratio %d\n",
 536                                       info->metadata_ratio);
 537                        }
 538                        break;
 539                case Opt_discard:
 540                        btrfs_set_opt(info->mount_opt, DISCARD);
 541                        break;
 542                case Opt_space_cache:
 543                        btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 544                        break;
 545                case Opt_no_space_cache:
 546                        printk(KERN_INFO "btrfs: disabling disk space caching\n");
 547                        btrfs_clear_opt(info->mount_opt, SPACE_CACHE);
 548                        break;
 549                case Opt_inode_cache:
 550                        printk(KERN_INFO "btrfs: enabling inode map caching\n");
 551                        btrfs_set_opt(info->mount_opt, INODE_MAP_CACHE);
 552                        break;
 553                case Opt_clear_cache:
 554                        printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 555                        btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
 556                        break;
 557                case Opt_user_subvol_rm_allowed:
 558                        btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 559                        break;
 560                case Opt_enospc_debug:
 561                        btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 562                        break;
 563                case Opt_defrag:
 564                        printk(KERN_INFO "btrfs: enabling auto defrag\n");
 565                        btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
 566                        break;
 567                case Opt_recovery:
 568                        printk(KERN_INFO "btrfs: enabling auto recovery\n");
 569                        btrfs_set_opt(info->mount_opt, RECOVERY);
 570                        break;
 571                case Opt_skip_balance:
 572                        btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
 573                        break;
 574#ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 575                case Opt_check_integrity_including_extent_data:
 576                        printk(KERN_INFO "btrfs: enabling check integrity"
 577                               " including extent data\n");
 578                        btrfs_set_opt(info->mount_opt,
 579                                      CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
 580                        btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 581                        break;
 582                case Opt_check_integrity:
 583                        printk(KERN_INFO "btrfs: enabling check integrity\n");
 584                        btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
 585                        break;
 586                case Opt_check_integrity_print_mask:
 587                        intarg = 0;
 588                        match_int(&args[0], &intarg);
 589                        if (intarg) {
 590                                info->check_integrity_print_mask = intarg;
 591                                printk(KERN_INFO "btrfs:"
 592                                       " check_integrity_print_mask 0x%x\n",
 593                                       info->check_integrity_print_mask);
 594                        }
 595                        break;
 596#else
 597                case Opt_check_integrity_including_extent_data:
 598                case Opt_check_integrity:
 599                case Opt_check_integrity_print_mask:
 600                        printk(KERN_ERR "btrfs: support for check_integrity*"
 601                               " not compiled in!\n");
 602                        ret = -EINVAL;
 603                        goto out;
 604#endif
 605                case Opt_fatal_errors:
 606                        if (strcmp(args[0].from, "panic") == 0)
 607                                btrfs_set_opt(info->mount_opt,
 608                                              PANIC_ON_FATAL_ERROR);
 609                        else if (strcmp(args[0].from, "bug") == 0)
 610                                btrfs_clear_opt(info->mount_opt,
 611                                              PANIC_ON_FATAL_ERROR);
 612                        else {
 613                                ret = -EINVAL;
 614                                goto out;
 615                        }
 616                        break;
 617                case Opt_err:
 618                        printk(KERN_INFO "btrfs: unrecognized mount option "
 619                               "'%s'\n", p);
 620                        ret = -EINVAL;
 621                        goto out;
 622                default:
 623                        break;
 624                }
 625        }
 626out:
 627        if (!ret && btrfs_test_opt(root, SPACE_CACHE))
 628                printk(KERN_INFO "btrfs: disk space caching is enabled\n");
 629        kfree(orig);
 630        return ret;
 631}
 632
 633/*
 634 * Parse mount options that are required early in the mount process.
 635 *
 636 * All other options will be parsed on much later in the mount process and
 637 * only when we need to allocate a new super block.
 638 */
 639static int btrfs_parse_early_options(const char *options, fmode_t flags,
 640                void *holder, char **subvol_name, u64 *subvol_objectid,
 641                u64 *subvol_rootid, struct btrfs_fs_devices **fs_devices)
 642{
 643        substring_t args[MAX_OPT_ARGS];
 644        char *device_name, *opts, *orig, *p;
 645        int error = 0;
 646        int intarg;
 647
 648        if (!options)
 649                return 0;
 650
 651        /*
 652         * strsep changes the string, duplicate it because parse_options
 653         * gets called twice
 654         */
 655        opts = kstrdup(options, GFP_KERNEL);
 656        if (!opts)
 657                return -ENOMEM;
 658        orig = opts;
 659
 660        while ((p = strsep(&opts, ",")) != NULL) {
 661                int token;
 662                if (!*p)
 663                        continue;
 664
 665                token = match_token(p, tokens, args);
 666                switch (token) {
 667                case Opt_subvol:
 668                        kfree(*subvol_name);
 669                        *subvol_name = match_strdup(&args[0]);
 670                        break;
 671                case Opt_subvolid:
 672                        intarg = 0;
 673                        error = match_int(&args[0], &intarg);
 674                        if (!error) {
 675                                /* we want the original fs_tree */
 676                                if (!intarg)
 677                                        *subvol_objectid =
 678                                                BTRFS_FS_TREE_OBJECTID;
 679                                else
 680                                        *subvol_objectid = intarg;
 681                        }
 682                        break;
 683                case Opt_subvolrootid:
 684                        intarg = 0;
 685                        error = match_int(&args[0], &intarg);
 686                        if (!error) {
 687                                /* we want the original fs_tree */
 688                                if (!intarg)
 689                                        *subvol_rootid =
 690                                                BTRFS_FS_TREE_OBJECTID;
 691                                else
 692                                        *subvol_rootid = intarg;
 693                        }
 694                        break;
 695                case Opt_device:
 696                        device_name = match_strdup(&args[0]);
 697                        if (!device_name) {
 698                                error = -ENOMEM;
 699                                goto out;
 700                        }
 701                        error = btrfs_scan_one_device(device_name,
 702                                        flags, holder, fs_devices);
 703                        kfree(device_name);
 704                        if (error)
 705                                goto out;
 706                        break;
 707                default:
 708                        break;
 709                }
 710        }
 711
 712out:
 713        kfree(orig);
 714        return error;
 715}
 716
 717static struct dentry *get_default_root(struct super_block *sb,
 718                                       u64 subvol_objectid)
 719{
 720        struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 721        struct btrfs_root *root = fs_info->tree_root;
 722        struct btrfs_root *new_root;
 723        struct btrfs_dir_item *di;
 724        struct btrfs_path *path;
 725        struct btrfs_key location;
 726        struct inode *inode;
 727        u64 dir_id;
 728        int new = 0;
 729
 730        /*
 731         * We have a specific subvol we want to mount, just setup location and
 732         * go look up the root.
 733         */
 734        if (subvol_objectid) {
 735                location.objectid = subvol_objectid;
 736                location.type = BTRFS_ROOT_ITEM_KEY;
 737                location.offset = (u64)-1;
 738                goto find_root;
 739        }
 740
 741        path = btrfs_alloc_path();
 742        if (!path)
 743                return ERR_PTR(-ENOMEM);
 744        path->leave_spinning = 1;
 745
 746        /*
 747         * Find the "default" dir item which points to the root item that we
 748         * will mount by default if we haven't been given a specific subvolume
 749         * to mount.
 750         */
 751        dir_id = btrfs_super_root_dir(fs_info->super_copy);
 752        di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 753        if (IS_ERR(di)) {
 754                btrfs_free_path(path);
 755                return ERR_CAST(di);
 756        }
 757        if (!di) {
 758                /*
 759                 * Ok the default dir item isn't there.  This is weird since
 760                 * it's always been there, but don't freak out, just try and
 761                 * mount to root most subvolume.
 762                 */
 763                btrfs_free_path(path);
 764                dir_id = BTRFS_FIRST_FREE_OBJECTID;
 765                new_root = fs_info->fs_root;
 766                goto setup_root;
 767        }
 768
 769        btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 770        btrfs_free_path(path);
 771
 772find_root:
 773        new_root = btrfs_read_fs_root_no_name(fs_info, &location);
 774        if (IS_ERR(new_root))
 775                return ERR_CAST(new_root);
 776
 777        if (btrfs_root_refs(&new_root->root_item) == 0)
 778                return ERR_PTR(-ENOENT);
 779
 780        dir_id = btrfs_root_dirid(&new_root->root_item);
 781setup_root:
 782        location.objectid = dir_id;
 783        location.type = BTRFS_INODE_ITEM_KEY;
 784        location.offset = 0;
 785
 786        inode = btrfs_iget(sb, &location, new_root, &new);
 787        if (IS_ERR(inode))
 788                return ERR_CAST(inode);
 789
 790        /*
 791         * If we're just mounting the root most subvol put the inode and return
 792         * a reference to the dentry.  We will have already gotten a reference
 793         * to the inode in btrfs_fill_super so we're good to go.
 794         */
 795        if (!new && sb->s_root->d_inode == inode) {
 796                iput(inode);
 797                return dget(sb->s_root);
 798        }
 799
 800        return d_obtain_alias(inode);
 801}
 802
 803static int btrfs_fill_super(struct super_block *sb,
 804                            struct btrfs_fs_devices *fs_devices,
 805                            void *data, int silent)
 806{
 807        struct inode *inode;
 808        struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 809        struct btrfs_key key;
 810        int err;
 811
 812        sb->s_maxbytes = MAX_LFS_FILESIZE;
 813        sb->s_magic = BTRFS_SUPER_MAGIC;
 814        sb->s_op = &btrfs_super_ops;
 815        sb->s_d_op = &btrfs_dentry_operations;
 816        sb->s_export_op = &btrfs_export_ops;
 817        sb->s_xattr = btrfs_xattr_handlers;
 818        sb->s_time_gran = 1;
 819#ifdef CONFIG_BTRFS_FS_POSIX_ACL
 820        sb->s_flags |= MS_POSIXACL;
 821#endif
 822        sb->s_flags |= MS_I_VERSION;
 823        err = open_ctree(sb, fs_devices, (char *)data);
 824        if (err) {
 825                printk("btrfs: open_ctree failed\n");
 826                return err;
 827        }
 828
 829        key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 830        key.type = BTRFS_INODE_ITEM_KEY;
 831        key.offset = 0;
 832        inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
 833        if (IS_ERR(inode)) {
 834                err = PTR_ERR(inode);
 835                goto fail_close;
 836        }
 837
 838        sb->s_root = d_make_root(inode);
 839        if (!sb->s_root) {
 840                err = -ENOMEM;
 841                goto fail_close;
 842        }
 843
 844        save_mount_options(sb, data);
 845        cleancache_init_fs(sb);
 846        sb->s_flags |= MS_ACTIVE;
 847        return 0;
 848
 849fail_close:
 850        close_ctree(fs_info->tree_root);
 851        return err;
 852}
 853
 854int btrfs_sync_fs(struct super_block *sb, int wait)
 855{
 856        struct btrfs_trans_handle *trans;
 857        struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 858        struct btrfs_root *root = fs_info->tree_root;
 859
 860        trace_btrfs_sync_fs(wait);
 861
 862        if (!wait) {
 863                filemap_flush(fs_info->btree_inode->i_mapping);
 864                return 0;
 865        }
 866
 867        btrfs_wait_ordered_extents(root, 0);
 868
 869        trans = btrfs_attach_transaction(root);
 870        if (IS_ERR(trans)) {
 871                /* no transaction, don't bother */
 872                if (PTR_ERR(trans) == -ENOENT)
 873                        return 0;
 874                return PTR_ERR(trans);
 875        }
 876        return btrfs_commit_transaction(trans, root);
 877}
 878
 879static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 880{
 881        struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
 882        struct btrfs_root *root = info->tree_root;
 883        char *compress_type;
 884
 885        if (btrfs_test_opt(root, DEGRADED))
 886                seq_puts(seq, ",degraded");
 887        if (btrfs_test_opt(root, NODATASUM))
 888                seq_puts(seq, ",nodatasum");
 889        if (btrfs_test_opt(root, NODATACOW))
 890                seq_puts(seq, ",nodatacow");
 891        if (btrfs_test_opt(root, NOBARRIER))
 892                seq_puts(seq, ",nobarrier");
 893        if (info->max_inline != 8192 * 1024)
 894                seq_printf(seq, ",max_inline=%llu",
 895                           (unsigned long long)info->max_inline);
 896        if (info->alloc_start != 0)
 897                seq_printf(seq, ",alloc_start=%llu",
 898                           (unsigned long long)info->alloc_start);
 899        if (info->thread_pool_size !=  min_t(unsigned long,
 900                                             num_online_cpus() + 2, 8))
 901                seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 902        if (btrfs_test_opt(root, COMPRESS)) {
 903                if (info->compress_type == BTRFS_COMPRESS_ZLIB)
 904                        compress_type = "zlib";
 905                else
 906                        compress_type = "lzo";
 907                if (btrfs_test_opt(root, FORCE_COMPRESS))
 908                        seq_printf(seq, ",compress-force=%s", compress_type);
 909                else
 910                        seq_printf(seq, ",compress=%s", compress_type);
 911        }
 912        if (btrfs_test_opt(root, NOSSD))
 913                seq_puts(seq, ",nossd");
 914        if (btrfs_test_opt(root, SSD_SPREAD))
 915                seq_puts(seq, ",ssd_spread");
 916        else if (btrfs_test_opt(root, SSD))
 917                seq_puts(seq, ",ssd");
 918        if (btrfs_test_opt(root, NOTREELOG))
 919                seq_puts(seq, ",notreelog");
 920        if (btrfs_test_opt(root, FLUSHONCOMMIT))
 921                seq_puts(seq, ",flushoncommit");
 922        if (btrfs_test_opt(root, DISCARD))
 923                seq_puts(seq, ",discard");
 924        if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 925                seq_puts(seq, ",noacl");
 926        if (btrfs_test_opt(root, SPACE_CACHE))
 927                seq_puts(seq, ",space_cache");
 928        else
 929                seq_puts(seq, ",nospace_cache");
 930        if (btrfs_test_opt(root, CLEAR_CACHE))
 931                seq_puts(seq, ",clear_cache");
 932        if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
 933                seq_puts(seq, ",user_subvol_rm_allowed");
 934        if (btrfs_test_opt(root, ENOSPC_DEBUG))
 935                seq_puts(seq, ",enospc_debug");
 936        if (btrfs_test_opt(root, AUTO_DEFRAG))
 937                seq_puts(seq, ",autodefrag");
 938        if (btrfs_test_opt(root, INODE_MAP_CACHE))
 939                seq_puts(seq, ",inode_cache");
 940        if (btrfs_test_opt(root, SKIP_BALANCE))
 941                seq_puts(seq, ",skip_balance");
 942        if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
 943                seq_puts(seq, ",fatal_errors=panic");
 944        return 0;
 945}
 946
 947static int btrfs_test_super(struct super_block *s, void *data)
 948{
 949        struct btrfs_fs_info *p = data;
 950        struct btrfs_fs_info *fs_info = btrfs_sb(s);
 951
 952        return fs_info->fs_devices == p->fs_devices;
 953}
 954
 955static int btrfs_set_super(struct super_block *s, void *data)
 956{
 957        int err = set_anon_super(s, data);
 958        if (!err)
 959                s->s_fs_info = data;
 960        return err;
 961}
 962
 963/*
 964 * subvolumes are identified by ino 256
 965 */
 966static inline int is_subvolume_inode(struct inode *inode)
 967{
 968        if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
 969                return 1;
 970        return 0;
 971}
 972
 973/*
 974 * This will strip out the subvol=%s argument for an argument string and add
 975 * subvolid=0 to make sure we get the actual tree root for path walking to the
 976 * subvol we want.
 977 */
 978static char *setup_root_args(char *args)
 979{
 980        unsigned len = strlen(args) + 2 + 1;
 981        char *src, *dst, *buf;
 982
 983        /*
 984         * We need the same args as before, but with this substitution:
 985         * s!subvol=[^,]+!subvolid=0!
 986         *
 987         * Since the replacement string is up to 2 bytes longer than the
 988         * original, allocate strlen(args) + 2 + 1 bytes.
 989         */
 990
 991        src = strstr(args, "subvol=");
 992        /* This shouldn't happen, but just in case.. */
 993        if (!src)
 994                return NULL;
 995
 996        buf = dst = kmalloc(len, GFP_NOFS);
 997        if (!buf)
 998                return NULL;
 999
1000        /*
1001         * If the subvol= arg is not at the start of the string,
1002         * copy whatever precedes it into buf.
1003         */
1004        if (src != args) {
1005                *src++ = '\0';
1006                strcpy(buf, args);
1007                dst += strlen(args);
1008        }
1009
1010        strcpy(dst, "subvolid=0");
1011        dst += strlen("subvolid=0");
1012
1013        /*
1014         * If there is a "," after the original subvol=... string,
1015         * copy that suffix into our buffer.  Otherwise, we're done.
1016         */
1017        src = strchr(src, ',');
1018        if (src)
1019                strcpy(dst, src);
1020
1021        return buf;
1022}
1023
1024static struct dentry *mount_subvol(const char *subvol_name, int flags,
1025                                   const char *device_name, char *data)
1026{
1027        struct dentry *root;
1028        struct vfsmount *mnt;
1029        char *newargs;
1030
1031        newargs = setup_root_args(data);
1032        if (!newargs)
1033                return ERR_PTR(-ENOMEM);
1034        mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
1035                             newargs);
1036        kfree(newargs);
1037        if (IS_ERR(mnt))
1038                return ERR_CAST(mnt);
1039
1040        root = mount_subtree(mnt, subvol_name);
1041
1042        if (!IS_ERR(root) && !is_subvolume_inode(root->d_inode)) {
1043                struct super_block *s = root->d_sb;
1044                dput(root);
1045                root = ERR_PTR(-EINVAL);
1046                deactivate_locked_super(s);
1047                printk(KERN_ERR "btrfs: '%s' is not a valid subvolume\n",
1048                                subvol_name);
1049        }
1050
1051        return root;
1052}
1053
1054/*
1055 * Find a superblock for the given device / mount point.
1056 *
1057 * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
1058 *        for multiple device setup.  Make sure to keep it in sync.
1059 */
1060static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1061                const char *device_name, void *data)
1062{
1063        struct block_device *bdev = NULL;
1064        struct super_block *s;
1065        struct dentry *root;
1066        struct btrfs_fs_devices *fs_devices = NULL;
1067        struct btrfs_fs_info *fs_info = NULL;
1068        fmode_t mode = FMODE_READ;
1069        char *subvol_name = NULL;
1070        u64 subvol_objectid = 0;
1071        u64 subvol_rootid = 0;
1072        int error = 0;
1073
1074        if (!(flags & MS_RDONLY))
1075                mode |= FMODE_WRITE;
1076
1077        error = btrfs_parse_early_options(data, mode, fs_type,
1078                                          &subvol_name, &subvol_objectid,
1079                                          &subvol_rootid, &fs_devices);
1080        if (error) {
1081                kfree(subvol_name);
1082                return ERR_PTR(error);
1083        }
1084
1085        if (subvol_name) {
1086                root = mount_subvol(subvol_name, flags, device_name, data);
1087                kfree(subvol_name);
1088                return root;
1089        }
1090
1091        error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1092        if (error)
1093                return ERR_PTR(error);
1094
1095        /*
1096         * Setup a dummy root and fs_info for test/set super.  This is because
1097         * we don't actually fill this stuff out until open_ctree, but we need
1098         * it for searching for existing supers, so this lets us do that and
1099         * then open_ctree will properly initialize everything later.
1100         */
1101        fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
1102        if (!fs_info)
1103                return ERR_PTR(-ENOMEM);
1104
1105        fs_info->fs_devices = fs_devices;
1106
1107        fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1108        fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1109        if (!fs_info->super_copy || !fs_info->super_for_commit) {
1110                error = -ENOMEM;
1111                goto error_fs_info;
1112        }
1113
1114        error = btrfs_open_devices(fs_devices, mode, fs_type);
1115        if (error)
1116                goto error_fs_info;
1117
1118        if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
1119                error = -EACCES;
1120                goto error_close_devices;
1121        }
1122
1123        bdev = fs_devices->latest_bdev;
1124        s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | MS_NOSEC,
1125                 fs_info);
1126        if (IS_ERR(s)) {
1127                error = PTR_ERR(s);
1128                goto error_close_devices;
1129        }
1130
1131        if (s->s_root) {
1132                btrfs_close_devices(fs_devices);
1133                free_fs_info(fs_info);
1134                if ((flags ^ s->s_flags) & MS_RDONLY)
1135                        error = -EBUSY;
1136        } else {
1137                char b[BDEVNAME_SIZE];
1138
1139                strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
1140                btrfs_sb(s)->bdev_holder = fs_type;
1141                error = btrfs_fill_super(s, fs_devices, data,
1142                                         flags & MS_SILENT ? 1 : 0);
1143        }
1144
1145        root = !error ? get_default_root(s, subvol_objectid) : ERR_PTR(error);
1146        if (IS_ERR(root))
1147                deactivate_locked_super(s);
1148
1149        return root;
1150
1151error_close_devices:
1152        btrfs_close_devices(fs_devices);
1153error_fs_info:
1154        free_fs_info(fs_info);
1155        return ERR_PTR(error);
1156}
1157
1158static void btrfs_set_max_workers(struct btrfs_workers *workers, int new_limit)
1159{
1160        spin_lock_irq(&workers->lock);
1161        workers->max_workers = new_limit;
1162        spin_unlock_irq(&workers->lock);
1163}
1164
1165static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1166                                     int new_pool_size, int old_pool_size)
1167{
1168        if (new_pool_size == old_pool_size)
1169                return;
1170
1171        fs_info->thread_pool_size = new_pool_size;
1172
1173        printk(KERN_INFO "btrfs: resize thread pool %d -> %d\n",
1174               old_pool_size, new_pool_size);
1175
1176        btrfs_set_max_workers(&fs_info->generic_worker, new_pool_size);
1177        btrfs_set_max_workers(&fs_info->workers, new_pool_size);
1178        btrfs_set_max_workers(&fs_info->delalloc_workers, new_pool_size);
1179        btrfs_set_max_workers(&fs_info->submit_workers, new_pool_size);
1180        btrfs_set_max_workers(&fs_info->caching_workers, new_pool_size);
1181        btrfs_set_max_workers(&fs_info->fixup_workers, new_pool_size);
1182        btrfs_set_max_workers(&fs_info->endio_workers, new_pool_size);
1183        btrfs_set_max_workers(&fs_info->endio_meta_workers, new_pool_size);
1184        btrfs_set_max_workers(&fs_info->endio_meta_write_workers, new_pool_size);
1185        btrfs_set_max_workers(&fs_info->endio_write_workers, new_pool_size);
1186        btrfs_set_max_workers(&fs_info->endio_freespace_worker, new_pool_size);
1187        btrfs_set_max_workers(&fs_info->delayed_workers, new_pool_size);
1188        btrfs_set_max_workers(&fs_info->readahead_workers, new_pool_size);
1189        btrfs_set_max_workers(&fs_info->scrub_workers, new_pool_size);
1190}
1191
1192static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1193{
1194        struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1195        struct btrfs_root *root = fs_info->tree_root;
1196        unsigned old_flags = sb->s_flags;
1197        unsigned long old_opts = fs_info->mount_opt;
1198        unsigned long old_compress_type = fs_info->compress_type;
1199        u64 old_max_inline = fs_info->max_inline;
1200        u64 old_alloc_start = fs_info->alloc_start;
1201        int old_thread_pool_size = fs_info->thread_pool_size;
1202        unsigned int old_metadata_ratio = fs_info->metadata_ratio;
1203        int ret;
1204
1205        ret = btrfs_parse_options(root, data);
1206        if (ret) {
1207                ret = -EINVAL;
1208                goto restore;
1209        }
1210
1211        btrfs_resize_thread_pool(fs_info,
1212                fs_info->thread_pool_size, old_thread_pool_size);
1213
1214        if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1215                return 0;
1216
1217        if (*flags & MS_RDONLY) {
1218                sb->s_flags |= MS_RDONLY;
1219
1220                ret = btrfs_commit_super(root);
1221                if (ret)
1222                        goto restore;
1223        } else {
1224                if (fs_info->fs_devices->rw_devices == 0) {
1225                        ret = -EACCES;
1226                        goto restore;
1227                }
1228
1229                if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1230                        ret = -EINVAL;
1231                        goto restore;
1232                }
1233
1234                ret = btrfs_cleanup_fs_roots(fs_info);
1235                if (ret)
1236                        goto restore;
1237
1238                /* recover relocation */
1239                ret = btrfs_recover_relocation(root);
1240                if (ret)
1241                        goto restore;
1242
1243                ret = btrfs_resume_balance_async(fs_info);
1244                if (ret)
1245                        goto restore;
1246
1247                sb->s_flags &= ~MS_RDONLY;
1248        }
1249
1250        return 0;
1251
1252restore:
1253        /* We've hit an error - don't reset MS_RDONLY */
1254        if (sb->s_flags & MS_RDONLY)
1255                old_flags |= MS_RDONLY;
1256        sb->s_flags = old_flags;
1257        fs_info->mount_opt = old_opts;
1258        fs_info->compress_type = old_compress_type;
1259        fs_info->max_inline = old_max_inline;
1260        fs_info->alloc_start = old_alloc_start;
1261        btrfs_resize_thread_pool(fs_info,
1262                old_thread_pool_size, fs_info->thread_pool_size);
1263        fs_info->metadata_ratio = old_metadata_ratio;
1264        return ret;
1265}
1266
1267/* Used to sort the devices by max_avail(descending sort) */
1268static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1269                                       const void *dev_info2)
1270{
1271        if (((struct btrfs_device_info *)dev_info1)->max_avail >
1272            ((struct btrfs_device_info *)dev_info2)->max_avail)
1273                return -1;
1274        else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1275                 ((struct btrfs_device_info *)dev_info2)->max_avail)
1276                return 1;
1277        else
1278        return 0;
1279}
1280
1281/*
1282 * sort the devices by max_avail, in which max free extent size of each device
1283 * is stored.(Descending Sort)
1284 */
1285static inline void btrfs_descending_sort_devices(
1286                                        struct btrfs_device_info *devices,
1287                                        size_t nr_devices)
1288{
1289        sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1290             btrfs_cmp_device_free_bytes, NULL);
1291}
1292
1293/*
1294 * The helper to calc the free space on the devices that can be used to store
1295 * file data.
1296 */
1297static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
1298{
1299        struct btrfs_fs_info *fs_info = root->fs_info;
1300        struct btrfs_device_info *devices_info;
1301        struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1302        struct btrfs_device *device;
1303        u64 skip_space;
1304        u64 type;
1305        u64 avail_space;
1306        u64 used_space;
1307        u64 min_stripe_size;
1308        int min_stripes = 1, num_stripes = 1;
1309        int i = 0, nr_devices;
1310        int ret;
1311
1312        nr_devices = fs_info->fs_devices->open_devices;
1313        BUG_ON(!nr_devices);
1314
1315        devices_info = kmalloc(sizeof(*devices_info) * nr_devices,
1316                               GFP_NOFS);
1317        if (!devices_info)
1318                return -ENOMEM;
1319
1320        /* calc min stripe number for data space alloction */
1321        type = btrfs_get_alloc_profile(root, 1);
1322        if (type & BTRFS_BLOCK_GROUP_RAID0) {
1323                min_stripes = 2;
1324                num_stripes = nr_devices;
1325        } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1326                min_stripes = 2;
1327                num_stripes = 2;
1328        } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1329                min_stripes = 4;
1330                num_stripes = 4;
1331        }
1332
1333        if (type & BTRFS_BLOCK_GROUP_DUP)
1334                min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1335        else
1336                min_stripe_size = BTRFS_STRIPE_LEN;
1337
1338        list_for_each_entry(device, &fs_devices->devices, dev_list) {
1339                if (!device->in_fs_metadata || !device->bdev)
1340                        continue;
1341
1342                avail_space = device->total_bytes - device->bytes_used;
1343
1344                /* align with stripe_len */
1345                do_div(avail_space, BTRFS_STRIPE_LEN);
1346                avail_space *= BTRFS_STRIPE_LEN;
1347
1348                /*
1349                 * In order to avoid overwritting the superblock on the drive,
1350                 * btrfs starts at an offset of at least 1MB when doing chunk
1351                 * allocation.
1352                 */
1353                skip_space = 1024 * 1024;
1354
1355                /* user can set the offset in fs_info->alloc_start. */
1356                if (fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1357                    device->total_bytes)
1358                        skip_space = max(fs_info->alloc_start, skip_space);
1359
1360                /*
1361                 * btrfs can not use the free space in [0, skip_space - 1],
1362                 * we must subtract it from the total. In order to implement
1363                 * it, we account the used space in this range first.
1364                 */
1365                ret = btrfs_account_dev_extents_size(device, 0, skip_space - 1,
1366                                                     &used_space);
1367                if (ret) {
1368                        kfree(devices_info);
1369                        return ret;
1370                }
1371
1372                /* calc the free space in [0, skip_space - 1] */
1373                skip_space -= used_space;
1374
1375                /*
1376                 * we can use the free space in [0, skip_space - 1], subtract
1377                 * it from the total.
1378                 */
1379                if (avail_space && avail_space >= skip_space)
1380                        avail_space -= skip_space;
1381                else
1382                        avail_space = 0;
1383
1384                if (avail_space < min_stripe_size)
1385                        continue;
1386
1387                devices_info[i].dev = device;
1388                devices_info[i].max_avail = avail_space;
1389
1390                i++;
1391        }
1392
1393        nr_devices = i;
1394
1395        btrfs_descending_sort_devices(devices_info, nr_devices);
1396
1397        i = nr_devices - 1;
1398        avail_space = 0;
1399        while (nr_devices >= min_stripes) {
1400                if (num_stripes > nr_devices)
1401                        num_stripes = nr_devices;
1402
1403                if (devices_info[i].max_avail >= min_stripe_size) {
1404                        int j;
1405                        u64 alloc_size;
1406
1407                        avail_space += devices_info[i].max_avail * num_stripes;
1408                        alloc_size = devices_info[i].max_avail;
1409                        for (j = i + 1 - num_stripes; j <= i; j++)
1410                                devices_info[j].max_avail -= alloc_size;
1411                }
1412                i--;
1413                nr_devices--;
1414        }
1415
1416        kfree(devices_info);
1417        *free_bytes = avail_space;
1418        return 0;
1419}
1420
1421static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1422{
1423        struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
1424        struct btrfs_super_block *disk_super = fs_info->super_copy;
1425        struct list_head *head = &fs_info->space_info;
1426        struct btrfs_space_info *found;
1427        u64 total_used = 0;
1428        u64 total_free_data = 0;
1429        int bits = dentry->d_sb->s_blocksize_bits;
1430        __be32 *fsid = (__be32 *)fs_info->fsid;
1431        int ret;
1432
1433        /* holding chunk_muext to avoid allocating new chunks */
1434        mutex_lock(&fs_info->chunk_mutex);
1435        rcu_read_lock();
1436        list_for_each_entry_rcu(found, head, list) {
1437                if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
1438                        total_free_data += found->disk_total - found->disk_used;
1439                        total_free_data -=
1440                                btrfs_account_ro_block_groups_free_space(found);
1441                }
1442
1443                total_used += found->disk_used;
1444        }
1445        rcu_read_unlock();
1446
1447        buf->f_namelen = BTRFS_NAME_LEN;
1448        buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
1449        buf->f_bfree = buf->f_blocks - (total_used >> bits);
1450        buf->f_bsize = dentry->d_sb->s_blocksize;
1451        buf->f_type = BTRFS_SUPER_MAGIC;
1452        buf->f_bavail = total_free_data;
1453        ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
1454        if (ret) {
1455                mutex_unlock(&fs_info->chunk_mutex);
1456                return ret;
1457        }
1458        buf->f_bavail += total_free_data;
1459        buf->f_bavail = buf->f_bavail >> bits;
1460        mutex_unlock(&fs_info->chunk_mutex);
1461
1462        /* We treat it as constant endianness (it doesn't matter _which_)
1463           because we want the fsid to come out the same whether mounted
1464           on a big-endian or little-endian host */
1465        buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
1466        buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
1467        /* Mask in the root object ID too, to disambiguate subvols */
1468        buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
1469        buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
1470
1471        return 0;
1472}
1473
1474static void btrfs_kill_super(struct super_block *sb)
1475{
1476        struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1477        kill_anon_super(sb);
1478        free_fs_info(fs_info);
1479}
1480
1481static struct file_system_type btrfs_fs_type = {
1482        .owner          = THIS_MODULE,
1483        .name           = "btrfs",
1484        .mount          = btrfs_mount,
1485        .kill_sb        = btrfs_kill_super,
1486        .fs_flags       = FS_REQUIRES_DEV,
1487};
1488
1489/*
1490 * used by btrfsctl to scan devices when no FS is mounted
1491 */
1492static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
1493                                unsigned long arg)
1494{
1495        struct btrfs_ioctl_vol_args *vol;
1496        struct btrfs_fs_devices *fs_devices;
1497        int ret = -ENOTTY;
1498
1499        if (!capable(CAP_SYS_ADMIN))
1500                return -EPERM;
1501
1502        vol = memdup_user((void __user *)arg, sizeof(*vol));
1503        if (IS_ERR(vol))
1504                return PTR_ERR(vol);
1505
1506        switch (cmd) {
1507        case BTRFS_IOC_SCAN_DEV:
1508                ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1509                                            &btrfs_fs_type, &fs_devices);
1510                break;
1511        case BTRFS_IOC_DEVICES_READY:
1512                ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1513                                            &btrfs_fs_type, &fs_devices);
1514                if (ret)
1515                        break;
1516                ret = !(fs_devices->num_devices == fs_devices->total_devices);
1517                break;
1518        }
1519
1520        kfree(vol);
1521        return ret;
1522}
1523
1524static int btrfs_freeze(struct super_block *sb)
1525{
1526        struct btrfs_trans_handle *trans;
1527        struct btrfs_root *root = btrfs_sb(sb)->tree_root;
1528
1529        trans = btrfs_attach_transaction(root);
1530        if (IS_ERR(trans)) {
1531                /* no transaction, don't bother */
1532                if (PTR_ERR(trans) == -ENOENT)
1533                        return 0;
1534                return PTR_ERR(trans);
1535        }
1536        return btrfs_commit_transaction(trans, root);
1537}
1538
1539static int btrfs_unfreeze(struct super_block *sb)
1540{
1541        return 0;
1542}
1543
1544static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
1545{
1546        struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
1547        struct btrfs_fs_devices *cur_devices;
1548        struct btrfs_device *dev, *first_dev = NULL;
1549        struct list_head *head;
1550        struct rcu_string *name;
1551
1552        mutex_lock(&fs_info->fs_devices->device_list_mutex);
1553        cur_devices = fs_info->fs_devices;
1554        while (cur_devices) {
1555                head = &cur_devices->devices;
1556                list_for_each_entry(dev, head, dev_list) {
1557                        if (dev->missing)
1558                                continue;
1559                        if (!first_dev || dev->devid < first_dev->devid)
1560                                first_dev = dev;
1561                }
1562                cur_devices = cur_devices->seed;
1563        }
1564
1565        if (first_dev) {
1566                rcu_read_lock();
1567                name = rcu_dereference(first_dev->name);
1568                seq_escape(m, name->str, " \t\n\\");
1569                rcu_read_unlock();
1570        } else {
1571                WARN_ON(1);
1572        }
1573        mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1574        return 0;
1575}
1576
1577static const struct super_operations btrfs_super_ops = {
1578        .drop_inode     = btrfs_drop_inode,
1579        .evict_inode    = btrfs_evict_inode,
1580        .put_super      = btrfs_put_super,
1581        .sync_fs        = btrfs_sync_fs,
1582        .show_options   = btrfs_show_options,
1583        .show_devname   = btrfs_show_devname,
1584        .write_inode    = btrfs_write_inode,
1585        .alloc_inode    = btrfs_alloc_inode,
1586        .destroy_inode  = btrfs_destroy_inode,
1587        .statfs         = btrfs_statfs,
1588        .remount_fs     = btrfs_remount,
1589        .freeze_fs      = btrfs_freeze,
1590        .unfreeze_fs    = btrfs_unfreeze,
1591};
1592
1593static const struct file_operations btrfs_ctl_fops = {
1594        .unlocked_ioctl  = btrfs_control_ioctl,
1595        .compat_ioctl = btrfs_control_ioctl,
1596        .owner   = THIS_MODULE,
1597        .llseek = noop_llseek,
1598};
1599
1600static struct miscdevice btrfs_misc = {
1601        .minor          = BTRFS_MINOR,
1602        .name           = "btrfs-control",
1603        .fops           = &btrfs_ctl_fops
1604};
1605
1606MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
1607MODULE_ALIAS("devname:btrfs-control");
1608
1609static int btrfs_interface_init(void)
1610{
1611        return misc_register(&btrfs_misc);
1612}
1613
1614static void btrfs_interface_exit(void)
1615{
1616        if (misc_deregister(&btrfs_misc) < 0)
1617                printk(KERN_INFO "btrfs: misc_deregister failed for control device\n");
1618}
1619
1620static int __init init_btrfs_fs(void)
1621{
1622        int err;
1623
1624        err = btrfs_init_sysfs();
1625        if (err)
1626                return err;
1627
1628        btrfs_init_compress();
1629
1630        err = btrfs_init_cachep();
1631        if (err)
1632                goto free_compress;
1633
1634        err = extent_io_init();
1635        if (err)
1636                goto free_cachep;
1637
1638        err = extent_map_init();
1639        if (err)
1640                goto free_extent_io;
1641
1642        err = ordered_data_init();
1643        if (err)
1644                goto free_extent_map;
1645
1646        err = btrfs_delayed_inode_init();
1647        if (err)
1648                goto free_ordered_data;
1649
1650        err = btrfs_interface_init();
1651        if (err)
1652                goto free_delayed_inode;
1653
1654        err = register_filesystem(&btrfs_fs_type);
1655        if (err)
1656                goto unregister_ioctl;
1657
1658        btrfs_init_lockdep();
1659
1660        printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
1661        return 0;
1662
1663unregister_ioctl:
1664        btrfs_interface_exit();
1665free_delayed_inode:
1666        btrfs_delayed_inode_exit();
1667free_ordered_data:
1668        ordered_data_exit();
1669free_extent_map:
1670        extent_map_exit();
1671free_extent_io:
1672        extent_io_exit();
1673free_cachep:
1674        btrfs_destroy_cachep();
1675free_compress:
1676        btrfs_exit_compress();
1677        btrfs_exit_sysfs();
1678        return err;
1679}
1680
1681static void __exit exit_btrfs_fs(void)
1682{
1683        btrfs_destroy_cachep();
1684        btrfs_delayed_inode_exit();
1685        ordered_data_exit();
1686        extent_map_exit();
1687        extent_io_exit();
1688        btrfs_interface_exit();
1689        unregister_filesystem(&btrfs_fs_type);
1690        btrfs_exit_sysfs();
1691        btrfs_cleanup_fs_uuids();
1692        btrfs_exit_compress();
1693}
1694
1695module_init(init_btrfs_fs)
1696module_exit(exit_btrfs_fs)
1697
1698MODULE_LICENSE("GPL");
1699
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