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