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 "compat.h"
  43 #include "delayed-inode.h"
  44 #include "ctree.h"
  45 #include "disk-io.h"
  46 #include "transaction.h"
  47 #include "btrfs_inode.h"
  48 #include "ioctl.h"
  49 #include "print-tree.h"
  50 #include "xattr.h"
  51 #include "volumes.h"
  52 #include "version.h"
  53 #include "export.h"
  54 #include "compression.h"
  55
  56 #define CREATE_TRACE_POINTS
  57 #include <trace/events/btrfs.h>
  58
  59 static const struct super_operations btrfs_super_ops;
  60
  61 static const char *btrfs_decode_error(struct btrfs_fs_info *fs_info, int errno,
  62                                       char nbuf[16])
  63 {
  64         char *errstr = NULL;
  65
  66         switch (errno) {
  67         case -EIO:
  68                 errstr = "IO failure";
  69                 break;
  70         case -ENOMEM:
  71                 errstr = "Out of memory";
  72                 break;
  73         case -EROFS:
  74                 errstr = "Readonly filesystem";
  75                 break;
  76         default:
  77                 if (nbuf) {
  78                         if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
  79                                 errstr = nbuf;
  80                 }
  81                 break;
  82         }
  83
  84         return errstr;
  85 }
  86
  87 static void __save_error_info(struct btrfs_fs_info *fs_info)
  88 {
  89         /*
  90          * today we only save the error info into ram.  Long term we'll
  91          * also send it down to the disk
  92          */
  93         fs_info->fs_state = BTRFS_SUPER_FLAG_ERROR;
  94 }
  95
  96 /* NOTE:
  97  *      We move write_super stuff at umount in order to avoid deadlock
  98  *      for umount hold all lock.
  99  */
 100 static void save_error_info(struct btrfs_fs_info *fs_info)
 101 {
 102         __save_error_info(fs_info);
 103 }
 104
 105 /* btrfs handle error by forcing the filesystem readonly */
 106 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
 107 {
 108         struct super_block *sb = fs_info->sb;
 109
 110         if (sb->s_flags & MS_RDONLY)
 111                 return;
 112
 113         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 114                 sb->s_flags |= MS_RDONLY;
 115                 printk(KERN_INFO "btrfs is forced readonly\n");
 116         }
 117 }
 118
 119 /*
 120  * __btrfs_std_error decodes expected errors from the caller and
 121  * invokes the approciate error response.
 122  */
 123 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
 124                      unsigned int line, int errno)
 125 {
 126         struct super_block *sb = fs_info->sb;
 127         char nbuf[16];
 128         const char *errstr;
 129
 130         /*
 131          * Special case: if the error is EROFS, and we're already
 132          * under MS_RDONLY, then it is safe here.
 133          */
 134         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 135                 return;
 136
 137         errstr = btrfs_decode_error(fs_info, errno, nbuf);
 138         printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: %s\n",
 139                 sb->s_id, function, line, errstr);
 140         save_error_info(fs_info);
 141
 142         btrfs_handle_error(fs_info);
 143 }
 144
 145 static void btrfs_put_super(struct super_block *sb)
 146 {
 147         struct btrfs_root *root = btrfs_sb(sb);
 148         int ret;
 149
 150         ret = close_ctree(root);
 151         sb->s_fs_info = NULL;
 152
 153         (void)ret; /* FIXME: need to fix VFS to return error? */
 154 }
 155
 156 enum {
 157         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 158         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 159         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 160         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 161         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 162         Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
 163         Opt_enospc_debug, Opt_subvolrootid, Opt_err,
 164 };
 165
 166 static match_table_t tokens = {
 167         {Opt_degraded, "degraded"},
 168         {Opt_subvol, "subvol=%s"},
 169         {Opt_subvolid, "subvolid=%d"},
 170         {Opt_device, "device=%s"},
 171         {Opt_nodatasum, "nodatasum"},
 172         {Opt_nodatacow, "nodatacow"},
 173         {Opt_nobarrier, "nobarrier"},
 174         {Opt_max_inline, "max_inline=%s"},
 175         {Opt_alloc_start, "alloc_start=%s"},
 176         {Opt_thread_pool, "thread_pool=%d"},
 177         {Opt_compress, "compress"},
 178         {Opt_compress_type, "compress=%s"},
 179         {Opt_compress_force, "compress-force"},
 180         {Opt_compress_force_type, "compress-force=%s"},
 181         {Opt_ssd, "ssd"},
 182         {Opt_ssd_spread, "ssd_spread"},
 183         {Opt_nossd, "nossd"},
 184         {Opt_noacl, "noacl"},
 185         {Opt_notreelog, "notreelog"},
 186         {Opt_flushoncommit, "flushoncommit"},
 187         {Opt_ratio, "metadata_ratio=%d"},
 188         {Opt_discard, "discard"},
 189         {Opt_space_cache, "space_cache"},
 190         {Opt_clear_cache, "clear_cache"},
 191         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 192         {Opt_enospc_debug, "enospc_debug"},
 193         {Opt_subvolrootid, "subvolrootid=%d"},
 194         {Opt_err, NULL},
 195 };
 196
 197 /*
 198  * Regular mount options parser.  Everything that is needed only when
 199  * reading in a new superblock is parsed here.
 200  */
 201 int btrfs_parse_options(struct btrfs_root *root, char *options)
 202 {
 203         struct btrfs_fs_info *info = root->fs_info;
 204         substring_t args[MAX_OPT_ARGS];
 205         char *p, *num, *orig;
 206         int intarg;
 207         int ret = 0;
 208         char *compress_type;
 209         bool compress_force = false;
 210
 211         if (!options)
 212                 return 0;
 213
 214         /*
 215          * strsep changes the string, duplicate it because parse_options
 216          * gets called twice
 217          */
 218         options = kstrdup(options, GFP_NOFS);
 219         if (!options)
 220                 return -ENOMEM;
 221
 222         orig = options;
 223
 224         while ((p = strsep(&options, ",")) != NULL) {
 225                 int token;
 226                 if (!*p)
 227                         continue;
 228
 229                 token = match_token(p, tokens, args);
 230                 switch (token) {
 231                 case Opt_degraded:
 232                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 233                         btrfs_set_opt(info->mount_opt, DEGRADED);
 234                         break;
 235                 case Opt_subvol:
 236                 case Opt_subvolid:
 237                 case Opt_subvolrootid:
 238                 case Opt_device:
 239                         /*
 240                          * These are parsed by btrfs_parse_early_options
 241                          * and can be happily ignored here.
 242                          */
 243                         break;
 244                 case Opt_nodatasum:
 245                         printk(KERN_INFO "btrfs: setting nodatasum\n");
 246                         btrfs_set_opt(info->mount_opt, NODATASUM);
 247                         break;
 248                 case Opt_nodatacow:
 249                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 250                         btrfs_set_opt(info->mount_opt, NODATACOW);
 251                         btrfs_set_opt(info->mount_opt, NODATASUM);
 252                         break;
 253                 case Opt_compress_force:
 254                 case Opt_compress_force_type:
 255                         compress_force = true;
 256                 case Opt_compress:
 257                 case Opt_compress_type:
 258                         if (token == Opt_compress ||
 259                             token == Opt_compress_force ||
 260                             strcmp(args[0].from, "zlib") == 0) {
 261                                 compress_type = "zlib";
 262                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 263                         } else if (strcmp(args[0].from, "lzo") == 0) {
 264                                 compress_type = "lzo";
 265                                 info->compress_type = BTRFS_COMPRESS_LZO;
 266                         } else {
 267                                 ret = -EINVAL;
 268                                 goto out;
 269                         }
 270
 271                         btrfs_set_opt(info->mount_opt, COMPRESS);
 272                         if (compress_force) {
 273                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 274                                 pr_info("btrfs: force %s compression\n",
 275                                         compress_type);
 276                         } else
 277                                 pr_info("btrfs: use %s compression\n",
 278                                         compress_type);
 279                         break;
 280                 case Opt_ssd:
 281                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 282                         btrfs_set_opt(info->mount_opt, SSD);
 283                         break;
 284                 case Opt_ssd_spread:
 285                         printk(KERN_INFO "btrfs: use spread ssd "
 286                                "allocation scheme\n");
 287                         btrfs_set_opt(info->mount_opt, SSD);
 288                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 289                         break;
 290                 case Opt_nossd:
 291                         printk(KERN_INFO "btrfs: not using ssd allocation "
 292                                "scheme\n");
 293                         btrfs_set_opt(info->mount_opt, NOSSD);
 294                         btrfs_clear_opt(info->mount_opt, SSD);
 295                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 296                         break;
 297                 case Opt_nobarrier:
 298                         printk(KERN_INFO "btrfs: turning off barriers\n");
 299                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 300                         break;
 301                 case Opt_thread_pool:
 302                         intarg = 0;
 303                         match_int(&args[0], &intarg);
 304                         if (intarg) {
 305                                 info->thread_pool_size = intarg;
 306                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 307                                        info->thread_pool_size);
 308                         }
 309                         break;
 310                 case Opt_max_inline:
 311                         num = match_strdup(&args[0]);
 312                         if (num) {
 313                                 info->max_inline = memparse(num, NULL);
 314                                 kfree(num);
 315
 316                                 if (info->max_inline) {
 317                                         info->max_inline = max_t(u64,
 318                                                 info->max_inline,
 319                                                 root->sectorsize);
 320                                 }
 321                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 322                                         (unsigned long long)info->max_inline);
 323                         }
 324                         break;
 325                 case Opt_alloc_start:
 326                         num = match_strdup(&args[0]);
 327                         if (num) {
 328                                 info->alloc_start = memparse(num, NULL);
 329                                 kfree(num);
 330                                 printk(KERN_INFO
 331                                         "btrfs: allocations start at %llu\n",
 332                                         (unsigned long long)info->alloc_start);
 333                         }
 334                         break;
 335                 case Opt_noacl:
 336                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 337                         break;
 338                 case Opt_notreelog:
 339                         printk(KERN_INFO "btrfs: disabling tree log\n");
 340                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 341                         break;
 342                 case Opt_flushoncommit:
 343                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 344                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 345                         break;
 346                 case Opt_ratio:
 347                         intarg = 0;
 348                         match_int(&args[0], &intarg);
 349                         if (intarg) {
 350                                 info->metadata_ratio = intarg;
 351                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 352                                        info->metadata_ratio);
 353                         }
 354                         break;
 355                 case Opt_discard:
 356                         btrfs_set_opt(info->mount_opt, DISCARD);
 357                         break;
 358                 case Opt_space_cache:
 359                         printk(KERN_INFO "btrfs: enabling disk space caching\n");
 360                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 361                         break;
 362                 case Opt_clear_cache:
 363                         printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 364                         btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
 365                         break;
 366                 case Opt_user_subvol_rm_allowed:
 367                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 368                         break;
 369                 case Opt_enospc_debug:
 370                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 371                         break;
 372                 case Opt_err:
 373                         printk(KERN_INFO "btrfs: unrecognized mount option "
 374                                "'%s'\n", p);
 375                         ret = -EINVAL;
 376                         goto out;
 377                 default:
 378                         break;
 379                 }
 380         }
 381 out:
 382         kfree(orig);
 383         return ret;
 384 }
 385
 386 /*
 387  * Parse mount options that are required early in the mount process.
 388  *
 389  * All other options will be parsed on much later in the mount process and
 390  * only when we need to allocate a new super block.
 391  */
 392 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 393                 void *holder, char **subvol_name, u64 *subvol_objectid,
 394                 u64 *subvol_rootid, struct btrfs_fs_devices **fs_devices)
 395 {
 396         substring_t args[MAX_OPT_ARGS];
 397         char *opts, *orig, *p;
 398         int error = 0;
 399         int intarg;
 400
 401         if (!options)
 402                 goto out;
 403
 404         /*
 405          * strsep changes the string, duplicate it because parse_options
 406          * gets called twice
 407          */
 408         opts = kstrdup(options, GFP_KERNEL);
 409         if (!opts)
 410                 return -ENOMEM;
 411         orig = opts;
 412
 413         while ((p = strsep(&opts, ",")) != NULL) {
 414                 int token;
 415                 if (!*p)
 416                         continue;
 417
 418                 token = match_token(p, tokens, args);
 419                 switch (token) {
 420                 case Opt_subvol:
 421                         *subvol_name = match_strdup(&args[0]);
 422                         break;
 423                 case Opt_subvolid:
 424                         intarg = 0;
 425                         error = match_int(&args[0], &intarg);
 426                         if (!error) {
 427                                 /* we want the original fs_tree */
 428                                 if (!intarg)
 429                                         *subvol_objectid =
 430                                                 BTRFS_FS_TREE_OBJECTID;
 431                                 else
 432                                         *subvol_objectid = intarg;
 433                         }
 434                         break;
 435                 case Opt_subvolrootid:
 436                         intarg = 0;
 437                         error = match_int(&args[0], &intarg);
 438                         if (!error) {
 439                                 /* we want the original fs_tree */
 440                                 if (!intarg)
 441                                         *subvol_rootid =
 442                                                 BTRFS_FS_TREE_OBJECTID;
 443                                 else
 444                                         *subvol_rootid = intarg;
 445                         }
 446                         break;
 447                 case Opt_device:
 448                         error = btrfs_scan_one_device(match_strdup(&args[0]),
 449                                         flags, holder, fs_devices);
 450                         if (error)
 451                                 goto out_free_opts;
 452                         break;
 453                 default:
 454                         break;
 455                 }
 456         }
 457
 458  out_free_opts:
 459         kfree(orig);
 460  out:
 461         /*
 462          * If no subvolume name is specified we use the default one.  Allocate
 463          * a copy of the string "." here so that code later in the
 464          * mount path doesn't care if it's the default volume or another one.
 465          */
 466         if (!*subvol_name) {
 467                 *subvol_name = kstrdup(".", GFP_KERNEL);
 468                 if (!*subvol_name)
 469                         return -ENOMEM;
 470         }
 471         return error;
 472 }
 473
 474 static struct dentry *get_default_root(struct super_block *sb,
 475                                        u64 subvol_objectid)
 476 {
 477         struct btrfs_root *root = sb->s_fs_info;
 478         struct btrfs_root *new_root;
 479         struct btrfs_dir_item *di;
 480         struct btrfs_path *path;
 481         struct btrfs_key location;
 482         struct inode *inode;
 483         struct dentry *dentry;
 484         u64 dir_id;
 485         int new = 0;
 486
 487         /*
 488          * We have a specific subvol we want to mount, just setup location and
 489          * go look up the root.
 490          */
 491         if (subvol_objectid) {
 492                 location.objectid = subvol_objectid;
 493                 location.type = BTRFS_ROOT_ITEM_KEY;
 494                 location.offset = (u64)-1;
 495                 goto find_root;
 496         }
 497
 498         path = btrfs_alloc_path();
 499         if (!path)
 500                 return ERR_PTR(-ENOMEM);
 501         path->leave_spinning = 1;
 502
 503         /*
 504          * Find the "default" dir item which points to the root item that we
 505          * will mount by default if we haven't been given a specific subvolume
 506          * to mount.
 507          */
 508         dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
 509         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 510         if (IS_ERR(di)) {
 511                 btrfs_free_path(path);
 512                 return ERR_CAST(di);
 513         }
 514         if (!di) {
 515                 /*
 516                  * Ok the default dir item isn't there.  This is weird since
 517                  * it's always been there, but don't freak out, just try and
 518                  * mount to root most subvolume.
 519                  */
 520                 btrfs_free_path(path);
 521                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
 522                 new_root = root->fs_info->fs_root;
 523                 goto setup_root;
 524         }
 525
 526         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 527         btrfs_free_path(path);
 528
 529 find_root:
 530         new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
 531         if (IS_ERR(new_root))
 532                 return ERR_CAST(new_root);
 533
 534         if (btrfs_root_refs(&new_root->root_item) == 0)
 535                 return ERR_PTR(-ENOENT);
 536
 537         dir_id = btrfs_root_dirid(&new_root->root_item);
 538 setup_root:
 539         location.objectid = dir_id;
 540         location.type = BTRFS_INODE_ITEM_KEY;
 541         location.offset = 0;
 542
 543         inode = btrfs_iget(sb, &location, new_root, &new);
 544         if (IS_ERR(inode))
 545                 return ERR_CAST(inode);
 546
 547         /*
 548          * If we're just mounting the root most subvol put the inode and return
 549          * a reference to the dentry.  We will have already gotten a reference
 550          * to the inode in btrfs_fill_super so we're good to go.
 551          */
 552         if (!new && sb->s_root->d_inode == inode) {
 553                 iput(inode);
 554                 return dget(sb->s_root);
 555         }
 556
 557         if (new) {
 558                 const struct qstr name = { .name = "/", .len = 1 };
 559
 560                 /*
 561                  * New inode, we need to make the dentry a sibling of s_root so
 562                  * everything gets cleaned up properly on unmount.
 563                  */
 564                 dentry = d_alloc(sb->s_root, &name);
 565                 if (!dentry) {
 566                         iput(inode);
 567                         return ERR_PTR(-ENOMEM);
 568                 }
 569                 d_splice_alias(inode, dentry);
 570         } else {
 571                 /*
 572                  * We found the inode in cache, just find a dentry for it and
 573                  * put the reference to the inode we just got.
 574                  */
 575                 dentry = d_find_alias(inode);
 576                 iput(inode);
 577         }
 578
 579         return dentry;
 580 }
 581
 582 static int btrfs_fill_super(struct super_block *sb,
 583                             struct btrfs_fs_devices *fs_devices,
 584                             void *data, int silent)
 585 {
 586         struct inode *inode;
 587         struct dentry *root_dentry;
 588         struct btrfs_root *tree_root;
 589         struct btrfs_key key;
 590         int err;
 591
 592         sb->s_maxbytes = MAX_LFS_FILESIZE;
 593         sb->s_magic = BTRFS_SUPER_MAGIC;
 594         sb->s_op = &btrfs_super_ops;
 595         sb->s_d_op = &btrfs_dentry_operations;
 596         sb->s_export_op = &btrfs_export_ops;
 597         sb->s_xattr = btrfs_xattr_handlers;
 598         sb->s_time_gran = 1;
 599 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 600         sb->s_flags |= MS_POSIXACL;
 601 #endif
 602
 603         tree_root = open_ctree(sb, fs_devices, (char *)data);
 604
 605         if (IS_ERR(tree_root)) {
 606                 printk("btrfs: open_ctree failed\n");
 607                 return PTR_ERR(tree_root);
 608         }
 609         sb->s_fs_info = tree_root;
 610
 611         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 612         key.type = BTRFS_INODE_ITEM_KEY;
 613         key.offset = 0;
 614         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);
 615         if (IS_ERR(inode)) {
 616                 err = PTR_ERR(inode);
 617                 goto fail_close;
 618         }
 619
 620         root_dentry = d_alloc_root(inode);
 621         if (!root_dentry) {
 622                 iput(inode);
 623                 err = -ENOMEM;
 624                 goto fail_close;
 625         }
 626
 627         sb->s_root = root_dentry;
 628
 629         save_mount_options(sb, data);
 630         return 0;
 631
 632 fail_close:
 633         close_ctree(tree_root);
 634         return err;
 635 }
 636
 637 int btrfs_sync_fs(struct super_block *sb, int wait)
 638 {
 639         struct btrfs_trans_handle *trans;
 640         struct btrfs_root *root = btrfs_sb(sb);
 641         int ret;
 642
 643         trace_btrfs_sync_fs(wait);
 644
 645         if (!wait) {
 646                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 647                 return 0;
 648         }
 649
 650         btrfs_start_delalloc_inodes(root, 0);
 651         btrfs_wait_ordered_extents(root, 0, 0);
 652
 653         trans = btrfs_start_transaction(root, 0);
 654         if (IS_ERR(trans))
 655                 return PTR_ERR(trans);
 656         ret = btrfs_commit_transaction(trans, root);
 657         return ret;
 658 }
 659
 660 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 661 {
 662         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 663         struct btrfs_fs_info *info = root->fs_info;
 664         char *compress_type;
 665
 666         if (btrfs_test_opt(root, DEGRADED))
 667                 seq_puts(seq, ",degraded");
 668         if (btrfs_test_opt(root, NODATASUM))
 669                 seq_puts(seq, ",nodatasum");
 670         if (btrfs_test_opt(root, NODATACOW))
 671                 seq_puts(seq, ",nodatacow");
 672         if (btrfs_test_opt(root, NOBARRIER))
 673                 seq_puts(seq, ",nobarrier");
 674         if (info->max_inline != 8192 * 1024)
 675                 seq_printf(seq, ",max_inline=%llu",
 676                            (unsigned long long)info->max_inline);
 677         if (info->alloc_start != 0)
 678                 seq_printf(seq, ",alloc_start=%llu",
 679                            (unsigned long long)info->alloc_start);
 680         if (info->thread_pool_size !=  min_t(unsigned long,
 681                                              num_online_cpus() + 2, 8))
 682                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 683         if (btrfs_test_opt(root, COMPRESS)) {
 684                 if (info->compress_type == BTRFS_COMPRESS_ZLIB)
 685                         compress_type = "zlib";
 686                 else
 687                         compress_type = "lzo";
 688                 if (btrfs_test_opt(root, FORCE_COMPRESS))
 689                         seq_printf(seq, ",compress-force=%s", compress_type);
 690                 else
 691                         seq_printf(seq, ",compress=%s", compress_type);
 692         }
 693         if (btrfs_test_opt(root, NOSSD))
 694                 seq_puts(seq, ",nossd");
 695         if (btrfs_test_opt(root, SSD_SPREAD))
 696                 seq_puts(seq, ",ssd_spread");
 697         else if (btrfs_test_opt(root, SSD))
 698                 seq_puts(seq, ",ssd");
 699         if (btrfs_test_opt(root, NOTREELOG))
 700                 seq_puts(seq, ",notreelog");
 701         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 702                 seq_puts(seq, ",flushoncommit");
 703         if (btrfs_test_opt(root, DISCARD))
 704                 seq_puts(seq, ",discard");
 705         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 706                 seq_puts(seq, ",noacl");
 707         if (btrfs_test_opt(root, SPACE_CACHE))
 708                 seq_puts(seq, ",space_cache");
 709         if (btrfs_test_opt(root, CLEAR_CACHE))
 710                 seq_puts(seq, ",clear_cache");
 711         if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
 712                 seq_puts(seq, ",user_subvol_rm_allowed");
 713         return 0;
 714 }
 715
 716 static int btrfs_test_super(struct super_block *s, void *data)
 717 {
 718         struct btrfs_root *test_root = data;
 719         struct btrfs_root *root = btrfs_sb(s);
 720
 721         /*
 722          * If this super block is going away, return false as it
 723          * can't match as an existing super block.
 724          */
 725         if (!atomic_read(&s->s_active))
 726                 return 0;
 727         return root->fs_info->fs_devices == test_root->fs_info->fs_devices;
 728 }
 729
 730 static int btrfs_set_super(struct super_block *s, void *data)
 731 {
 732         s->s_fs_info = data;
 733
 734         return set_anon_super(s, data);
 735 }
 736
 737
 738 /*
 739  * Find a superblock for the given device / mount point.
 740  *
 741  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 742  *        for multiple device setup.  Make sure to keep it in sync.
 743  */
 744 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 745                 const char *device_name, void *data)
 746 {
 747         struct block_device *bdev = NULL;
 748         struct super_block *s;
 749         struct dentry *root;
 750         struct btrfs_fs_devices *fs_devices = NULL;
 751         struct btrfs_root *tree_root = NULL;
 752         struct btrfs_fs_info *fs_info = NULL;
 753         fmode_t mode = FMODE_READ;
 754         char *subvol_name = NULL;
 755         u64 subvol_objectid = 0;
 756         u64 subvol_rootid = 0;
 757         int error = 0;
 758
 759         if (!(flags & MS_RDONLY))
 760                 mode |= FMODE_WRITE;
 761
 762         error = btrfs_parse_early_options(data, mode, fs_type,
 763                                           &subvol_name, &subvol_objectid,
 764                                           &subvol_rootid, &fs_devices);
 765         if (error)
 766                 return ERR_PTR(error);
 767
 768         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
 769         if (error)
 770                 goto error_free_subvol_name;
 771
 772         error = btrfs_open_devices(fs_devices, mode, fs_type);
 773         if (error)
 774                 goto error_free_subvol_name;
 775
 776         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 777                 error = -EACCES;
 778                 goto error_close_devices;
 779         }
 780
 781         /*
 782          * Setup a dummy root and fs_info for test/set super.  This is because
 783          * we don't actually fill this stuff out until open_ctree, but we need
 784          * it for searching for existing supers, so this lets us do that and
 785          * then open_ctree will properly initialize everything later.
 786          */
 787         fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
 788         tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
 789         if (!fs_info || !tree_root) {
 790                 error = -ENOMEM;
 791                 goto error_close_devices;
 792         }
 793         fs_info->tree_root = tree_root;
 794         fs_info->fs_devices = fs_devices;
 795         tree_root->fs_info = fs_info;
 796
 797         bdev = fs_devices->latest_bdev;
 798         s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
 799         if (IS_ERR(s))
 800                 goto error_s;
 801
 802         if (s->s_root) {
 803                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 804                         deactivate_locked_super(s);
 805                         error = -EBUSY;
 806                         goto error_close_devices;
 807                 }
 808
 809                 btrfs_close_devices(fs_devices);
 810                 kfree(fs_info);
 811                 kfree(tree_root);
 812         } else {
 813                 char b[BDEVNAME_SIZE];
 814
 815                 s->s_flags = flags;
 816                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 817                 error = btrfs_fill_super(s, fs_devices, data,
 818                                          flags & MS_SILENT ? 1 : 0);
 819                 if (error) {
 820                         deactivate_locked_super(s);
 821                         goto error_free_subvol_name;
 822                 }
 823
 824                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 825                 s->s_flags |= MS_ACTIVE;
 826         }
 827
 828         /* if they gave us a subvolume name bind mount into that */
 829         if (strcmp(subvol_name, ".")) {
 830                 struct dentry *new_root;
 831
 832                 root = get_default_root(s, subvol_rootid);
 833                 if (IS_ERR(root)) {
 834                         error = PTR_ERR(root);
 835                         deactivate_locked_super(s);
 836                         goto error_free_subvol_name;
 837                 }
 838
 839                 mutex_lock(&root->d_inode->i_mutex);
 840                 new_root = lookup_one_len(subvol_name, root,
 841                                       strlen(subvol_name));
 842                 mutex_unlock(&root->d_inode->i_mutex);
 843
 844                 if (IS_ERR(new_root)) {
 845                         dput(root);
 846                         deactivate_locked_super(s);
 847                         error = PTR_ERR(new_root);
 848                         goto error_free_subvol_name;
 849                 }
 850                 if (!new_root->d_inode) {
 851                         dput(root);
 852                         dput(new_root);
 853                         deactivate_locked_super(s);
 854                         error = -ENXIO;
 855                         goto error_free_subvol_name;
 856                 }
 857                 dput(root);
 858                 root = new_root;
 859         } else {
 860                 root = get_default_root(s, subvol_objectid);
 861                 if (IS_ERR(root)) {
 862                         error = PTR_ERR(root);
 863                         deactivate_locked_super(s);
 864                         goto error_free_subvol_name;
 865                 }
 866         }
 867
 868         kfree(subvol_name);
 869         return root;
 870
 871 error_s:
 872         error = PTR_ERR(s);
 873 error_close_devices:
 874         btrfs_close_devices(fs_devices);
 875         kfree(fs_info);
 876         kfree(tree_root);
 877 error_free_subvol_name:
 878         kfree(subvol_name);
 879         return ERR_PTR(error);
 880 }
 881
 882 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 883 {
 884         struct btrfs_root *root = btrfs_sb(sb);
 885         int ret;
 886
 887         ret = btrfs_parse_options(root, data);
 888         if (ret)
 889                 return -EINVAL;
 890
 891         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 892                 return 0;
 893
 894         if (*flags & MS_RDONLY) {
 895                 sb->s_flags |= MS_RDONLY;
 896
 897                 ret =  btrfs_commit_super(root);
 898                 WARN_ON(ret);
 899         } else {
 900                 if (root->fs_info->fs_devices->rw_devices == 0)
 901                         return -EACCES;
 902
 903                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 904                         return -EINVAL;
 905
 906                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 907                 WARN_ON(ret);
 908
 909                 /* recover relocation */
 910                 ret = btrfs_recover_relocation(root);
 911                 WARN_ON(ret);
 912
 913                 sb->s_flags &= ~MS_RDONLY;
 914         }
 915
 916         return 0;
 917 }
 918
 919 /* Used to sort the devices by max_avail(descending sort) */
 920 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
 921                                        const void *dev_info2)
 922 {
 923         if (((struct btrfs_device_info *)dev_info1)->max_avail >
 924             ((struct btrfs_device_info *)dev_info2)->max_avail)
 925                 return -1;
 926         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
 927                  ((struct btrfs_device_info *)dev_info2)->max_avail)
 928                 return 1;
 929         else
 930         return 0;
 931 }
 932
 933 /*
 934  * sort the devices by max_avail, in which max free extent size of each device
 935  * is stored.(Descending Sort)
 936  */
 937 static inline void btrfs_descending_sort_devices(
 938                                         struct btrfs_device_info *devices,
 939                                         size_t nr_devices)
 940 {
 941         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
 942              btrfs_cmp_device_free_bytes, NULL);
 943 }
 944
 945 /*
 946  * The helper to calc the free space on the devices that can be used to store
 947  * file data.
 948  */
 949 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
 950 {
 951         struct btrfs_fs_info *fs_info = root->fs_info;
 952         struct btrfs_device_info *devices_info;
 953         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 954         struct btrfs_device *device;
 955         u64 skip_space;
 956         u64 type;
 957         u64 avail_space;
 958         u64 used_space;
 959         u64 min_stripe_size;
 960         int min_stripes = 1;
 961         int i = 0, nr_devices;
 962         int ret;
 963
 964         nr_devices = fs_info->fs_devices->rw_devices;
 965         BUG_ON(!nr_devices);
 966
 967         devices_info = kmalloc(sizeof(*devices_info) * nr_devices,
 968                                GFP_NOFS);
 969         if (!devices_info)
 970                 return -ENOMEM;
 971
 972         /* calc min stripe number for data space alloction */
 973         type = btrfs_get_alloc_profile(root, 1);
 974         if (type & BTRFS_BLOCK_GROUP_RAID0)
 975                 min_stripes = 2;
 976         else if (type & BTRFS_BLOCK_GROUP_RAID1)
 977                 min_stripes = 2;
 978         else if (type & BTRFS_BLOCK_GROUP_RAID10)
 979                 min_stripes = 4;
 980
 981         if (type & BTRFS_BLOCK_GROUP_DUP)
 982                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
 983         else
 984                 min_stripe_size = BTRFS_STRIPE_LEN;
 985
 986         list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) {
 987                 if (!device->in_fs_metadata)
 988                         continue;
 989
 990                 avail_space = device->total_bytes - device->bytes_used;
 991
 992                 /* align with stripe_len */
 993                 do_div(avail_space, BTRFS_STRIPE_LEN);
 994                 avail_space *= BTRFS_STRIPE_LEN;
 995
 996                 /*
 997                  * In order to avoid overwritting the superblock on the drive,
 998                  * btrfs starts at an offset of at least 1MB when doing chunk
 999                  * allocation.
1000                  */
1001                 skip_space = 1024 * 1024;
1002
1003                 /* user can set the offset in fs_info->alloc_start. */
1004                 if (fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1005                     device->total_bytes)
1006                         skip_space = max(fs_info->alloc_start, skip_space);
1007
1008                 /*
1009                  * btrfs can not use the free space in [0, skip_space - 1],
1010                  * we must subtract it from the total. In order to implement
1011                  * it, we account the used space in this range first.
1012                  */
1013                 ret = btrfs_account_dev_extents_size(device, 0, skip_space - 1,
1014                                                      &used_space);
1015                 if (ret) {
1016                         kfree(devices_info);
1017                         return ret;
1018                 }
1019
1020                 /* calc the free space in [0, skip_space - 1] */
1021                 skip_space -= used_space;
1022
1023                 /*
1024                  * we can use the free space in [0, skip_space - 1], subtract
1025                  * it from the total.
1026                  */
1027                 if (avail_space && avail_space >= skip_space)
1028                         avail_space -= skip_space;
1029                 else
1030                         avail_space = 0;
1031
1032                 if (avail_space < min_stripe_size)
1033                         continue;
1034
1035                 devices_info[i].dev = device;
1036                 devices_info[i].max_avail = avail_space;
1037
1038                 i++;
1039         }
1040
1041         nr_devices = i;
1042
1043         btrfs_descending_sort_devices(devices_info, nr_devices);
1044
1045         i = nr_devices - 1;
1046         avail_space = 0;
1047         while (nr_devices >= min_stripes) {
1048                 if (devices_info[i].max_avail >= min_stripe_size) {
1049                         int j;
1050                         u64 alloc_size;
1051
1052                         avail_space += devices_info[i].max_avail * min_stripes;
1053                         alloc_size = devices_info[i].max_avail;
1054                         for (j = i + 1 - min_stripes; j <= i; j++)
1055                                 devices_info[j].max_avail -= alloc_size;
1056                 }
1057                 i--;
1058                 nr_devices--;
1059         }
1060
1061         kfree(devices_info);
1062         *free_bytes = avail_space;
1063         return 0;
1064 }
1065
1066 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1067 {
1068         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
1069         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
1070         struct list_head *head = &root->fs_info->space_info;
1071         struct btrfs_space_info *found;
1072         u64 total_used = 0;
1073         u64 total_free_data = 0;
1074         int bits = dentry->d_sb->s_blocksize_bits;
1075         __be32 *fsid = (__be32 *)root->fs_info->fsid;
1076         int ret;
1077
1078         /* holding chunk_muext to avoid allocating new chunks */
1079         mutex_lock(&root->fs_info->chunk_mutex);
1080         rcu_read_lock();
1081         list_for_each_entry_rcu(found, head, list) {
1082                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
1083                         total_free_data += found->disk_total - found->disk_used;
1084                         total_free_data -=
1085                                 btrfs_account_ro_block_groups_free_space(found);
1086                 }
1087
1088                 total_used += found->disk_used;
1089         }
1090         rcu_read_unlock();
1091
1092         buf->f_namelen = BTRFS_NAME_LEN;
1093         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
1094         buf->f_bfree = buf->f_blocks - (total_used >> bits);
1095         buf->f_bsize = dentry->d_sb->s_blocksize;
1096         buf->f_type = BTRFS_SUPER_MAGIC;
1097         buf->f_bavail = total_free_data;
1098         ret = btrfs_calc_avail_data_space(root, &total_free_data);
1099         if (ret) {
1100                 mutex_unlock(&root->fs_info->chunk_mutex);
1101                 return ret;
1102         }
1103         buf->f_bavail += total_free_data;
1104         buf->f_bavail = buf->f_bavail >> bits;
1105         mutex_unlock(&root->fs_info->chunk_mutex);
1106
1107         /* We treat it as constant endianness (it doesn't matter _which_)
1108            because we want the fsid to come out the same whether mounted
1109            on a big-endian or little-endian host */
1110         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
1111         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
1112         /* Mask in the root object ID too, to disambiguate subvols */
1113         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
1114         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
1115
1116         return 0;
1117 }
1118
1119 static struct file_system_type btrfs_fs_type = {
1120         .owner          = THIS_MODULE,
1121         .name           = "btrfs",
1122         .mount          = btrfs_mount,
1123         .kill_sb        = kill_anon_super,
1124         .fs_flags       = FS_REQUIRES_DEV,
1125 };
1126
1127 /*
1128  * used by btrfsctl to scan devices when no FS is mounted
1129  */
1130 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
1131                                 unsigned long arg)
1132 {
1133         struct btrfs_ioctl_vol_args *vol;
1134         struct btrfs_fs_devices *fs_devices;
1135         int ret = -ENOTTY;
1136
1137         if (!capable(CAP_SYS_ADMIN))
1138                 return -EPERM;
1139
1140         vol = memdup_user((void __user *)arg, sizeof(*vol));
1141         if (IS_ERR(vol))
1142                 return PTR_ERR(vol);
1143
1144         switch (cmd) {
1145         case BTRFS_IOC_SCAN_DEV:
1146                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1147                                             &btrfs_fs_type, &fs_devices);
1148                 break;
1149         }
1150
1151         kfree(vol);
1152         return ret;
1153 }
1154
1155 static int btrfs_freeze(struct super_block *sb)
1156 {
1157         struct btrfs_root *root = btrfs_sb(sb);
1158         mutex_lock(&root->fs_info->transaction_kthread_mutex);
1159         mutex_lock(&root->fs_info->cleaner_mutex);
1160         return 0;
1161 }
1162
1163 static int btrfs_unfreeze(struct super_block *sb)
1164 {
1165         struct btrfs_root *root = btrfs_sb(sb);
1166         mutex_unlock(&root->fs_info->cleaner_mutex);
1167         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
1168         return 0;
1169 }
1170
1171 static const struct super_operations btrfs_super_ops = {
1172         .drop_inode     = btrfs_drop_inode,
1173         .evict_inode    = btrfs_evict_inode,
1174         .put_super      = btrfs_put_super,
1175         .sync_fs        = btrfs_sync_fs,
1176         .show_options   = btrfs_show_options,
1177         .write_inode    = btrfs_write_inode,
1178         .dirty_inode    = btrfs_dirty_inode,
1179         .alloc_inode    = btrfs_alloc_inode,
1180         .destroy_inode  = btrfs_destroy_inode,
1181         .statfs         = btrfs_statfs,
1182         .remount_fs     = btrfs_remount,
1183         .freeze_fs      = btrfs_freeze,
1184         .unfreeze_fs    = btrfs_unfreeze,
1185 };
1186
1187 static const struct file_operations btrfs_ctl_fops = {
1188         .unlocked_ioctl  = btrfs_control_ioctl,
1189         .compat_ioctl = btrfs_control_ioctl,
1190         .owner   = THIS_MODULE,
1191         .llseek = noop_llseek,
1192 };
1193
1194 static struct miscdevice btrfs_misc = {
1195         .minor          = BTRFS_MINOR,
1196         .name           = "btrfs-control",
1197         .fops           = &btrfs_ctl_fops
1198 };
1199
1200 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
1201 MODULE_ALIAS("devname:btrfs-control");
1202
1203 static int btrfs_interface_init(void)
1204 {
1205         return misc_register(&btrfs_misc);
1206 }
1207
1208 static void btrfs_interface_exit(void)
1209 {
1210         if (misc_deregister(&btrfs_misc) < 0)
1211                 printk(KERN_INFO "misc_deregister failed for control device");
1212 }
1213
1214 static int __init init_btrfs_fs(void)
1215 {
1216         int err;
1217
1218         err = btrfs_init_sysfs();
1219         if (err)
1220                 return err;
1221
1222         err = btrfs_init_compress();
1223         if (err)
1224                 goto free_sysfs;
1225
1226         err = btrfs_init_cachep();
1227         if (err)
1228                 goto free_compress;
1229
1230         err = extent_io_init();
1231         if (err)
1232                 goto free_cachep;
1233
1234         err = extent_map_init();
1235         if (err)
1236                 goto free_extent_io;
1237
1238         err = btrfs_delayed_inode_init();
1239         if (err)
1240                 goto free_extent_map;
1241
1242         err = btrfs_interface_init();
1243         if (err)
1244                 goto free_delayed_inode;
1245
1246         err = register_filesystem(&btrfs_fs_type);
1247         if (err)
1248                 goto unregister_ioctl;
1249
1250         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
1251         return 0;
1252
1253 unregister_ioctl:
1254         btrfs_interface_exit();
1255 free_delayed_inode:
1256         btrfs_delayed_inode_exit();
1257 free_extent_map:
1258         extent_map_exit();
1259 free_extent_io:
1260         extent_io_exit();
1261 free_cachep:
1262         btrfs_destroy_cachep();
1263 free_compress:
1264         btrfs_exit_compress();
1265 free_sysfs:
1266         btrfs_exit_sysfs();
1267         return err;
1268 }
1269
1270 static void __exit exit_btrfs_fs(void)
1271 {
1272         btrfs_destroy_cachep();
1273         btrfs_delayed_inode_exit();
1274         extent_map_exit();
1275         extent_io_exit();
1276         btrfs_interface_exit();
1277         unregister_filesystem(&btrfs_fs_type);
1278         btrfs_exit_sysfs();
1279         btrfs_cleanup_fs_uuids();
1280         btrfs_exit_compress();
1281 }
1282
1283 module_init(init_btrfs_fs)
1284 module_exit(exit_btrfs_fs)
1285
1286 MODULE_LICENSE("GPL");