fs/btrfs/super.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/module.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/fs.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/highmem.h>
  25 #include <linux/time.h>
  26 #include <linux/init.h>
  27 #include <linux/seq_file.h>
  28 #include <linux/string.h>
  29 #include <linux/backing-dev.h>
  30 #include <linux/mount.h>
  31 #include <linux/mpage.h>
  32 #include <linux/swap.h>
  33 #include <linux/writeback.h>
  34 #include <linux/statfs.h>
  35 #include <linux/compat.h>
  36 #include <linux/parser.h>
  37 #include <linux/ctype.h>
  38 #include <linux/namei.h>
  39 #include <linux/miscdevice.h>
  40 #include <linux/magic.h>
  41 #include <linux/slab.h>
  42 #include <linux/cleancache.h>
  43 #include "compat.h"
  44 #include "delayed-inode.h"
  45 #include "ctree.h"
  46 #include "disk-io.h"
  47 #include "transaction.h"
  48 #include "btrfs_inode.h"
  49 #include "ioctl.h"
  50 #include "print-tree.h"
  51 #include "xattr.h"
  52 #include "volumes.h"
  53 #include "version.h"
  54 #include "export.h"
  55 #include "compression.h"
  56
  57 #define CREATE_TRACE_POINTS
  58 #include <trace/events/btrfs.h>
  59
  60 static const struct super_operations btrfs_super_ops;
  61
  62 static const char *btrfs_decode_error(struct btrfs_fs_info *fs_info, int errno,
  63                                       char nbuf[16])
  64 {
  65         char *errstr = NULL;
  66
  67         switch (errno) {
  68         case -EIO:
  69                 errstr = "IO failure";
  70                 break;
  71         case -ENOMEM:
  72                 errstr = "Out of memory";
  73                 break;
  74         case -EROFS:
  75                 errstr = "Readonly filesystem";
  76                 break;
  77         default:
  78                 if (nbuf) {
  79                         if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
  80                                 errstr = nbuf;
  81                 }
  82                 break;
  83         }
  84
  85         return errstr;
  86 }
  87
  88 static void __save_error_info(struct btrfs_fs_info *fs_info)
  89 {
  90         /*
  91          * today we only save the error info into ram.  Long term we'll
  92          * also send it down to the disk
  93          */
  94         fs_info->fs_state = BTRFS_SUPER_FLAG_ERROR;
  95 }
  96
  97 /* NOTE:
  98  *      We move write_super stuff at umount in order to avoid deadlock
  99  *      for umount hold all lock.
 100  */
 101 static void save_error_info(struct btrfs_fs_info *fs_info)
 102 {
 103         __save_error_info(fs_info);
 104 }
 105
 106 /* btrfs handle error by forcing the filesystem readonly */
 107 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
 108 {
 109         struct super_block *sb = fs_info->sb;
 110
 111         if (sb->s_flags & MS_RDONLY)
 112                 return;
 113
 114         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 115                 sb->s_flags |= MS_RDONLY;
 116                 printk(KERN_INFO "btrfs is forced readonly\n");
 117         }
 118 }
 119
 120 /*
 121  * __btrfs_std_error decodes expected errors from the caller and
 122  * invokes the approciate error response.
 123  */
 124 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
 125                      unsigned int line, int errno)
 126 {
 127         struct super_block *sb = fs_info->sb;
 128         char nbuf[16];
 129         const char *errstr;
 130
 131         /*
 132          * Special case: if the error is EROFS, and we're already
 133          * under MS_RDONLY, then it is safe here.
 134          */
 135         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
 136                 return;
 137
 138         errstr = btrfs_decode_error(fs_info, errno, nbuf);
 139         printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: %s\n",
 140                 sb->s_id, function, line, errstr);
 141         save_error_info(fs_info);
 142
 143         btrfs_handle_error(fs_info);
 144 }
 145
 146 static void btrfs_put_super(struct super_block *sb)
 147 {
 148         struct btrfs_root *root = btrfs_sb(sb);
 149         int ret;
 150
 151         ret = close_ctree(root);
 152         sb->s_fs_info = NULL;
 153
 154         (void)ret; /* FIXME: need to fix VFS to return error? */
 155 }
 156
 157 enum {
 158         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
 159         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
 160         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
 161         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
 162         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 163         Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
 164         Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_err,
 165 };
 166
 167 static match_table_t tokens = {
 168         {Opt_degraded, "degraded"},
 169         {Opt_subvol, "subvol=%s"},
 170         {Opt_subvolid, "subvolid=%d"},
 171         {Opt_device, "device=%s"},
 172         {Opt_nodatasum, "nodatasum"},
 173         {Opt_nodatacow, "nodatacow"},
 174         {Opt_nobarrier, "nobarrier"},
 175         {Opt_max_inline, "max_inline=%s"},
 176         {Opt_alloc_start, "alloc_start=%s"},
 177         {Opt_thread_pool, "thread_pool=%d"},
 178         {Opt_compress, "compress"},
 179         {Opt_compress_type, "compress=%s"},
 180         {Opt_compress_force, "compress-force"},
 181         {Opt_compress_force_type, "compress-force=%s"},
 182         {Opt_ssd, "ssd"},
 183         {Opt_ssd_spread, "ssd_spread"},
 184         {Opt_nossd, "nossd"},
 185         {Opt_noacl, "noacl"},
 186         {Opt_notreelog, "notreelog"},
 187         {Opt_flushoncommit, "flushoncommit"},
 188         {Opt_ratio, "metadata_ratio=%d"},
 189         {Opt_discard, "discard"},
 190         {Opt_space_cache, "space_cache"},
 191         {Opt_clear_cache, "clear_cache"},
 192         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
 193         {Opt_enospc_debug, "enospc_debug"},
 194         {Opt_subvolrootid, "subvolrootid=%d"},
 195         {Opt_defrag, "autodefrag"},
 196         {Opt_err, NULL},
 197 };
 198
 199 /*
 200  * Regular mount options parser.  Everything that is needed only when
 201  * reading in a new superblock is parsed here.
 202  */
 203 int btrfs_parse_options(struct btrfs_root *root, char *options)
 204 {
 205         struct btrfs_fs_info *info = root->fs_info;
 206         substring_t args[MAX_OPT_ARGS];
 207         char *p, *num, *orig;
 208         int intarg;
 209         int ret = 0;
 210         char *compress_type;
 211         bool compress_force = false;
 212
 213         if (!options)
 214                 return 0;
 215
 216         /*
 217          * strsep changes the string, duplicate it because parse_options
 218          * gets called twice
 219          */
 220         options = kstrdup(options, GFP_NOFS);
 221         if (!options)
 222                 return -ENOMEM;
 223
 224         orig = options;
 225
 226         while ((p = strsep(&options, ",")) != NULL) {
 227                 int token;
 228                 if (!*p)
 229                         continue;
 230
 231                 token = match_token(p, tokens, args);
 232                 switch (token) {
 233                 case Opt_degraded:
 234                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
 235                         btrfs_set_opt(info->mount_opt, DEGRADED);
 236                         break;
 237                 case Opt_subvol:
 238                 case Opt_subvolid:
 239                 case Opt_subvolrootid:
 240                 case Opt_device:
 241                         /*
 242                          * These are parsed by btrfs_parse_early_options
 243                          * and can be happily ignored here.
 244                          */
 245                         break;
 246                 case Opt_nodatasum:
 247                         printk(KERN_INFO "btrfs: setting nodatasum\n");
 248                         btrfs_set_opt(info->mount_opt, NODATASUM);
 249                         break;
 250                 case Opt_nodatacow:
 251                         printk(KERN_INFO "btrfs: setting nodatacow\n");
 252                         btrfs_set_opt(info->mount_opt, NODATACOW);
 253                         btrfs_set_opt(info->mount_opt, NODATASUM);
 254                         break;
 255                 case Opt_compress_force:
 256                 case Opt_compress_force_type:
 257                         compress_force = true;
 258                 case Opt_compress:
 259                 case Opt_compress_type:
 260                         if (token == Opt_compress ||
 261                             token == Opt_compress_force ||
 262                             strcmp(args[0].from, "zlib") == 0) {
 263                                 compress_type = "zlib";
 264                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
 265                         } else if (strcmp(args[0].from, "lzo") == 0) {
 266                                 compress_type = "lzo";
 267                                 info->compress_type = BTRFS_COMPRESS_LZO;
 268                         } else {
 269                                 ret = -EINVAL;
 270                                 goto out;
 271                         }
 272
 273                         btrfs_set_opt(info->mount_opt, COMPRESS);
 274                         if (compress_force) {
 275                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
 276                                 pr_info("btrfs: force %s compression\n",
 277                                         compress_type);
 278                         } else
 279                                 pr_info("btrfs: use %s compression\n",
 280                                         compress_type);
 281                         break;
 282                 case Opt_ssd:
 283                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
 284                         btrfs_set_opt(info->mount_opt, SSD);
 285                         break;
 286                 case Opt_ssd_spread:
 287                         printk(KERN_INFO "btrfs: use spread ssd "
 288                                "allocation scheme\n");
 289                         btrfs_set_opt(info->mount_opt, SSD);
 290                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
 291                         break;
 292                 case Opt_nossd:
 293                         printk(KERN_INFO "btrfs: not using ssd allocation "
 294                                "scheme\n");
 295                         btrfs_set_opt(info->mount_opt, NOSSD);
 296                         btrfs_clear_opt(info->mount_opt, SSD);
 297                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
 298                         break;
 299                 case Opt_nobarrier:
 300                         printk(KERN_INFO "btrfs: turning off barriers\n");
 301                         btrfs_set_opt(info->mount_opt, NOBARRIER);
 302                         break;
 303                 case Opt_thread_pool:
 304                         intarg = 0;
 305                         match_int(&args[0], &intarg);
 306                         if (intarg) {
 307                                 info->thread_pool_size = intarg;
 308                                 printk(KERN_INFO "btrfs: thread pool %d\n",
 309                                        info->thread_pool_size);
 310                         }
 311                         break;
 312                 case Opt_max_inline:
 313                         num = match_strdup(&args[0]);
 314                         if (num) {
 315                                 info->max_inline = memparse(num, NULL);
 316                                 kfree(num);
 317
 318                                 if (info->max_inline) {
 319                                         info->max_inline = max_t(u64,
 320                                                 info->max_inline,
 321                                                 root->sectorsize);
 322                                 }
 323                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
 324                                         (unsigned long long)info->max_inline);
 325                         }
 326                         break;
 327                 case Opt_alloc_start:
 328                         num = match_strdup(&args[0]);
 329                         if (num) {
 330                                 info->alloc_start = memparse(num, NULL);
 331                                 kfree(num);
 332                                 printk(KERN_INFO
 333                                         "btrfs: allocations start at %llu\n",
 334                                         (unsigned long long)info->alloc_start);
 335                         }
 336                         break;
 337                 case Opt_noacl:
 338                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
 339                         break;
 340                 case Opt_notreelog:
 341                         printk(KERN_INFO "btrfs: disabling tree log\n");
 342                         btrfs_set_opt(info->mount_opt, NOTREELOG);
 343                         break;
 344                 case Opt_flushoncommit:
 345                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
 346                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
 347                         break;
 348                 case Opt_ratio:
 349                         intarg = 0;
 350                         match_int(&args[0], &intarg);
 351                         if (intarg) {
 352                                 info->metadata_ratio = intarg;
 353                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
 354                                        info->metadata_ratio);
 355                         }
 356                         break;
 357                 case Opt_discard:
 358                         btrfs_set_opt(info->mount_opt, DISCARD);
 359                         break;
 360                 case Opt_space_cache:
 361                         printk(KERN_INFO "btrfs: enabling disk space caching\n");
 362                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
 363                         break;
 364                 case Opt_clear_cache:
 365                         printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 366                         btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
 367                         break;
 368                 case Opt_user_subvol_rm_allowed:
 369                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 370                         break;
 371                 case Opt_enospc_debug:
 372                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 373                         break;
 374                 case Opt_defrag:
 375                         printk(KERN_INFO "btrfs: enabling auto defrag");
 376                         btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
 377                         break;
 378                 case Opt_err:
 379                         printk(KERN_INFO "btrfs: unrecognized mount option "
 380                                "'%s'\n", p);
 381                         ret = -EINVAL;
 382                         goto out;
 383                 default:
 384                         break;
 385                 }
 386         }
 387 out:
 388         kfree(orig);
 389         return ret;
 390 }
 391
 392 /*
 393  * Parse mount options that are required early in the mount process.
 394  *
 395  * All other options will be parsed on much later in the mount process and
 396  * only when we need to allocate a new super block.
 397  */
 398 static int btrfs_parse_early_options(const char *options, fmode_t flags,
 399                 void *holder, char **subvol_name, u64 *subvol_objectid,
 400                 u64 *subvol_rootid, struct btrfs_fs_devices **fs_devices)
 401 {
 402         substring_t args[MAX_OPT_ARGS];
 403         char *opts, *orig, *p;
 404         int error = 0;
 405         int intarg;
 406
 407         if (!options)
 408                 goto out;
 409
 410         /*
 411          * strsep changes the string, duplicate it because parse_options
 412          * gets called twice
 413          */
 414         opts = kstrdup(options, GFP_KERNEL);
 415         if (!opts)
 416                 return -ENOMEM;
 417         orig = opts;
 418
 419         while ((p = strsep(&opts, ",")) != NULL) {
 420                 int token;
 421                 if (!*p)
 422                         continue;
 423
 424                 token = match_token(p, tokens, args);
 425                 switch (token) {
 426                 case Opt_subvol:
 427                         *subvol_name = match_strdup(&args[0]);
 428                         break;
 429                 case Opt_subvolid:
 430                         intarg = 0;
 431                         error = match_int(&args[0], &intarg);
 432                         if (!error) {
 433                                 /* we want the original fs_tree */
 434                                 if (!intarg)
 435                                         *subvol_objectid =
 436                                                 BTRFS_FS_TREE_OBJECTID;
 437                                 else
 438                                         *subvol_objectid = intarg;
 439                         }
 440                         break;
 441                 case Opt_subvolrootid:
 442                         intarg = 0;
 443                         error = match_int(&args[0], &intarg);
 444                         if (!error) {
 445                                 /* we want the original fs_tree */
 446                                 if (!intarg)
 447                                         *subvol_rootid =
 448                                                 BTRFS_FS_TREE_OBJECTID;
 449                                 else
 450                                         *subvol_rootid = intarg;
 451                         }
 452                         break;
 453                 case Opt_device:
 454                         error = btrfs_scan_one_device(match_strdup(&args[0]),
 455                                         flags, holder, fs_devices);
 456                         if (error)
 457                                 goto out_free_opts;
 458                         break;
 459                 default:
 460                         break;
 461                 }
 462         }
 463
 464  out_free_opts:
 465         kfree(orig);
 466  out:
 467         /*
 468          * If no subvolume name is specified we use the default one.  Allocate
 469          * a copy of the string "." here so that code later in the
 470          * mount path doesn't care if it's the default volume or another one.
 471          */
 472         if (!*subvol_name) {
 473                 *subvol_name = kstrdup(".", GFP_KERNEL);
 474                 if (!*subvol_name)
 475                         return -ENOMEM;
 476         }
 477         return error;
 478 }
 479
 480 static struct dentry *get_default_root(struct super_block *sb,
 481                                        u64 subvol_objectid)
 482 {
 483         struct btrfs_root *root = sb->s_fs_info;
 484         struct btrfs_root *new_root;
 485         struct btrfs_dir_item *di;
 486         struct btrfs_path *path;
 487         struct btrfs_key location;
 488         struct inode *inode;
 489         struct dentry *dentry;
 490         u64 dir_id;
 491         int new = 0;
 492
 493         /*
 494          * We have a specific subvol we want to mount, just setup location and
 495          * go look up the root.
 496          */
 497         if (subvol_objectid) {
 498                 location.objectid = subvol_objectid;
 499                 location.type = BTRFS_ROOT_ITEM_KEY;
 500                 location.offset = (u64)-1;
 501                 goto find_root;
 502         }
 503
 504         path = btrfs_alloc_path();
 505         if (!path)
 506                 return ERR_PTR(-ENOMEM);
 507         path->leave_spinning = 1;
 508
 509         /*
 510          * Find the "default" dir item which points to the root item that we
 511          * will mount by default if we haven't been given a specific subvolume
 512          * to mount.
 513          */
 514         dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
 515         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
 516         if (IS_ERR(di)) {
 517                 btrfs_free_path(path);
 518                 return ERR_CAST(di);
 519         }
 520         if (!di) {
 521                 /*
 522                  * Ok the default dir item isn't there.  This is weird since
 523                  * it's always been there, but don't freak out, just try and
 524                  * mount to root most subvolume.
 525                  */
 526                 btrfs_free_path(path);
 527                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
 528                 new_root = root->fs_info->fs_root;
 529                 goto setup_root;
 530         }
 531
 532         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
 533         btrfs_free_path(path);
 534
 535 find_root:
 536         new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
 537         if (IS_ERR(new_root))
 538                 return ERR_CAST(new_root);
 539
 540         if (btrfs_root_refs(&new_root->root_item) == 0)
 541                 return ERR_PTR(-ENOENT);
 542
 543         dir_id = btrfs_root_dirid(&new_root->root_item);
 544 setup_root:
 545         location.objectid = dir_id;
 546         location.type = BTRFS_INODE_ITEM_KEY;
 547         location.offset = 0;
 548
 549         inode = btrfs_iget(sb, &location, new_root, &new);
 550         if (IS_ERR(inode))
 551                 return ERR_CAST(inode);
 552
 553         /*
 554          * If we're just mounting the root most subvol put the inode and return
 555          * a reference to the dentry.  We will have already gotten a reference
 556          * to the inode in btrfs_fill_super so we're good to go.
 557          */
 558         if (!new && sb->s_root->d_inode == inode) {
 559                 iput(inode);
 560                 return dget(sb->s_root);
 561         }
 562
 563         if (new) {
 564                 const struct qstr name = { .name = "/", .len = 1 };
 565
 566                 /*
 567                  * New inode, we need to make the dentry a sibling of s_root so
 568                  * everything gets cleaned up properly on unmount.
 569                  */
 570                 dentry = d_alloc(sb->s_root, &name);
 571                 if (!dentry) {
 572                         iput(inode);
 573                         return ERR_PTR(-ENOMEM);
 574                 }
 575                 d_splice_alias(inode, dentry);
 576         } else {
 577                 /*
 578                  * We found the inode in cache, just find a dentry for it and
 579                  * put the reference to the inode we just got.
 580                  */
 581                 dentry = d_find_alias(inode);
 582                 iput(inode);
 583         }
 584
 585         return dentry;
 586 }
 587
 588 static int btrfs_fill_super(struct super_block *sb,
 589                             struct btrfs_fs_devices *fs_devices,
 590                             void *data, int silent)
 591 {
 592         struct inode *inode;
 593         struct dentry *root_dentry;
 594         struct btrfs_root *tree_root;
 595         struct btrfs_key key;
 596         int err;
 597
 598         sb->s_maxbytes = MAX_LFS_FILESIZE;
 599         sb->s_magic = BTRFS_SUPER_MAGIC;
 600         sb->s_op = &btrfs_super_ops;
 601         sb->s_d_op = &btrfs_dentry_operations;
 602         sb->s_export_op = &btrfs_export_ops;
 603         sb->s_xattr = btrfs_xattr_handlers;
 604         sb->s_time_gran = 1;
 605 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 606         sb->s_flags |= MS_POSIXACL;
 607 #endif
 608
 609         tree_root = open_ctree(sb, fs_devices, (char *)data);
 610
 611         if (IS_ERR(tree_root)) {
 612                 printk("btrfs: open_ctree failed\n");
 613                 return PTR_ERR(tree_root);
 614         }
 615         sb->s_fs_info = tree_root;
 616
 617         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 618         key.type = BTRFS_INODE_ITEM_KEY;
 619         key.offset = 0;
 620         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);
 621         if (IS_ERR(inode)) {
 622                 err = PTR_ERR(inode);
 623                 goto fail_close;
 624         }
 625
 626         root_dentry = d_alloc_root(inode);
 627         if (!root_dentry) {
 628                 iput(inode);
 629                 err = -ENOMEM;
 630                 goto fail_close;
 631         }
 632
 633         sb->s_root = root_dentry;
 634
 635         save_mount_options(sb, data);
 636         cleancache_init_fs(sb);
 637         return 0;
 638
 639 fail_close:
 640         close_ctree(tree_root);
 641         return err;
 642 }
 643
 644 int btrfs_sync_fs(struct super_block *sb, int wait)
 645 {
 646         struct btrfs_trans_handle *trans;
 647         struct btrfs_root *root = btrfs_sb(sb);
 648         int ret;
 649
 650         trace_btrfs_sync_fs(wait);
 651
 652         if (!wait) {
 653                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 654                 return 0;
 655         }
 656
 657         btrfs_start_delalloc_inodes(root, 0);
 658         btrfs_wait_ordered_extents(root, 0, 0);
 659
 660         trans = btrfs_start_transaction(root, 0);
 661         if (IS_ERR(trans))
 662                 return PTR_ERR(trans);
 663         ret = btrfs_commit_transaction(trans, root);
 664         return ret;
 665 }
 666
 667 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 668 {
 669         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
 670         struct btrfs_fs_info *info = root->fs_info;
 671         char *compress_type;
 672
 673         if (btrfs_test_opt(root, DEGRADED))
 674                 seq_puts(seq, ",degraded");
 675         if (btrfs_test_opt(root, NODATASUM))
 676                 seq_puts(seq, ",nodatasum");
 677         if (btrfs_test_opt(root, NODATACOW))
 678                 seq_puts(seq, ",nodatacow");
 679         if (btrfs_test_opt(root, NOBARRIER))
 680                 seq_puts(seq, ",nobarrier");
 681         if (info->max_inline != 8192 * 1024)
 682                 seq_printf(seq, ",max_inline=%llu",
 683                            (unsigned long long)info->max_inline);
 684         if (info->alloc_start != 0)
 685                 seq_printf(seq, ",alloc_start=%llu",
 686                            (unsigned long long)info->alloc_start);
 687         if (info->thread_pool_size !=  min_t(unsigned long,
 688                                              num_online_cpus() + 2, 8))
 689                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
 690         if (btrfs_test_opt(root, COMPRESS)) {
 691                 if (info->compress_type == BTRFS_COMPRESS_ZLIB)
 692                         compress_type = "zlib";
 693                 else
 694                         compress_type = "lzo";
 695                 if (btrfs_test_opt(root, FORCE_COMPRESS))
 696                         seq_printf(seq, ",compress-force=%s", compress_type);
 697                 else
 698                         seq_printf(seq, ",compress=%s", compress_type);
 699         }
 700         if (btrfs_test_opt(root, NOSSD))
 701                 seq_puts(seq, ",nossd");
 702         if (btrfs_test_opt(root, SSD_SPREAD))
 703                 seq_puts(seq, ",ssd_spread");
 704         else if (btrfs_test_opt(root, SSD))
 705                 seq_puts(seq, ",ssd");
 706         if (btrfs_test_opt(root, NOTREELOG))
 707                 seq_puts(seq, ",notreelog");
 708         if (btrfs_test_opt(root, FLUSHONCOMMIT))
 709                 seq_puts(seq, ",flushoncommit");
 710         if (btrfs_test_opt(root, DISCARD))
 711                 seq_puts(seq, ",discard");
 712         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
 713                 seq_puts(seq, ",noacl");
 714         if (btrfs_test_opt(root, SPACE_CACHE))
 715                 seq_puts(seq, ",space_cache");
 716         if (btrfs_test_opt(root, CLEAR_CACHE))
 717                 seq_puts(seq, ",clear_cache");
 718         if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
 719                 seq_puts(seq, ",user_subvol_rm_allowed");
 720         return 0;
 721 }
 722
 723 static int btrfs_test_super(struct super_block *s, void *data)
 724 {
 725         struct btrfs_root *test_root = data;
 726         struct btrfs_root *root = btrfs_sb(s);
 727
 728         /*
 729          * If this super block is going away, return false as it
 730          * can't match as an existing super block.
 731          */
 732         if (!atomic_read(&s->s_active))
 733                 return 0;
 734         return root->fs_info->fs_devices == test_root->fs_info->fs_devices;
 735 }
 736
 737 static int btrfs_set_super(struct super_block *s, void *data)
 738 {
 739         s->s_fs_info = data;
 740
 741         return set_anon_super(s, data);
 742 }
 743
 744
 745 /*
 746  * Find a superblock for the given device / mount point.
 747  *
 748  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 749  *        for multiple device setup.  Make sure to keep it in sync.
 750  */
 751 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 752                 const char *device_name, void *data)
 753 {
 754         struct block_device *bdev = NULL;
 755         struct super_block *s;
 756         struct dentry *root;
 757         struct btrfs_fs_devices *fs_devices = NULL;
 758         struct btrfs_root *tree_root = NULL;
 759         struct btrfs_fs_info *fs_info = NULL;
 760         fmode_t mode = FMODE_READ;
 761         char *subvol_name = NULL;
 762         u64 subvol_objectid = 0;
 763         u64 subvol_rootid = 0;
 764         int error = 0;
 765
 766         if (!(flags & MS_RDONLY))
 767                 mode |= FMODE_WRITE;
 768
 769         error = btrfs_parse_early_options(data, mode, fs_type,
 770                                           &subvol_name, &subvol_objectid,
 771                                           &subvol_rootid, &fs_devices);
 772         if (error)
 773                 return ERR_PTR(error);
 774
 775         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
 776         if (error)
 777                 goto error_free_subvol_name;
 778
 779         error = btrfs_open_devices(fs_devices, mode, fs_type);
 780         if (error)
 781                 goto error_free_subvol_name;
 782
 783         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
 784                 error = -EACCES;
 785                 goto error_close_devices;
 786         }
 787
 788         /*
 789          * Setup a dummy root and fs_info for test/set super.  This is because
 790          * we don't actually fill this stuff out until open_ctree, but we need
 791          * it for searching for existing supers, so this lets us do that and
 792          * then open_ctree will properly initialize everything later.
 793          */
 794         fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
 795         tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
 796         if (!fs_info || !tree_root) {
 797                 error = -ENOMEM;
 798                 goto error_close_devices;
 799         }
 800         fs_info->tree_root = tree_root;
 801         fs_info->fs_devices = fs_devices;
 802         tree_root->fs_info = fs_info;
 803
 804         bdev = fs_devices->latest_bdev;
 805         s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
 806         if (IS_ERR(s))
 807                 goto error_s;
 808
 809         if (s->s_root) {
 810                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 811                         deactivate_locked_super(s);
 812                         error = -EBUSY;
 813                         goto error_close_devices;
 814                 }
 815
 816                 btrfs_close_devices(fs_devices);
 817                 kfree(fs_info);
 818                 kfree(tree_root);
 819         } else {
 820                 char b[BDEVNAME_SIZE];
 821
 822                 s->s_flags = flags;
 823                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 824                 error = btrfs_fill_super(s, fs_devices, data,
 825                                          flags & MS_SILENT ? 1 : 0);
 826                 if (error) {
 827                         deactivate_locked_super(s);
 828                         goto error_free_subvol_name;
 829                 }
 830
 831                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 832                 s->s_flags |= MS_ACTIVE;
 833         }
 834
 835         /* if they gave us a subvolume name bind mount into that */
 836         if (strcmp(subvol_name, ".")) {
 837                 struct dentry *new_root;
 838
 839                 root = get_default_root(s, subvol_rootid);
 840                 if (IS_ERR(root)) {
 841                         error = PTR_ERR(root);
 842                         deactivate_locked_super(s);
 843                         goto error_free_subvol_name;
 844                 }
 845
 846                 mutex_lock(&root->d_inode->i_mutex);
 847                 new_root = lookup_one_len(subvol_name, root,
 848                                       strlen(subvol_name));
 849                 mutex_unlock(&root->d_inode->i_mutex);
 850
 851                 if (IS_ERR(new_root)) {
 852                         dput(root);
 853                         deactivate_locked_super(s);
 854                         error = PTR_ERR(new_root);
 855                         goto error_free_subvol_name;
 856                 }
 857                 if (!new_root->d_inode) {
 858                         dput(root);
 859                         dput(new_root);
 860                         deactivate_locked_super(s);
 861                         error = -ENXIO;
 862                         goto error_free_subvol_name;
 863                 }
 864                 dput(root);
 865                 root = new_root;
 866         } else {
 867                 root = get_default_root(s, subvol_objectid);
 868                 if (IS_ERR(root)) {
 869                         error = PTR_ERR(root);
 870                         deactivate_locked_super(s);
 871                         goto error_free_subvol_name;
 872                 }
 873         }
 874
 875         kfree(subvol_name);
 876         return root;
 877
 878 error_s:
 879         error = PTR_ERR(s);
 880 error_close_devices:
 881         btrfs_close_devices(fs_devices);
 882         kfree(fs_info);
 883         kfree(tree_root);
 884 error_free_subvol_name:
 885         kfree(subvol_name);
 886         return ERR_PTR(error);
 887 }
 888
 889 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 890 {
 891         struct btrfs_root *root = btrfs_sb(sb);
 892         int ret;
 893
 894         ret = btrfs_parse_options(root, data);
 895         if (ret)
 896                 return -EINVAL;
 897
 898         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 899                 return 0;
 900
 901         if (*flags & MS_RDONLY) {
 902                 sb->s_flags |= MS_RDONLY;
 903
 904                 ret =  btrfs_commit_super(root);
 905                 WARN_ON(ret);
 906         } else {
 907                 if (root->fs_info->fs_devices->rw_devices == 0)
 908                         return -EACCES;
 909
 910                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
 911                         return -EINVAL;
 912
 913                 ret = btrfs_cleanup_fs_roots(root->fs_info);
 914                 WARN_ON(ret);
 915
 916                 /* recover relocation */
 917                 ret = btrfs_recover_relocation(root);
 918                 WARN_ON(ret);
 919
 920                 sb->s_flags &= ~MS_RDONLY;
 921         }
 922
 923         return 0;
 924 }
 925
 926 /* Used to sort the devices by max_avail(descending sort) */
 927 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
 928                                        const void *dev_info2)
 929 {
 930         if (((struct btrfs_device_info *)dev_info1)->max_avail >
 931             ((struct btrfs_device_info *)dev_info2)->max_avail)
 932                 return -1;
 933         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
 934                  ((struct btrfs_device_info *)dev_info2)->max_avail)
 935                 return 1;
 936         else
 937         return 0;
 938 }
 939
 940 /*
 941  * sort the devices by max_avail, in which max free extent size of each device
 942  * is stored.(Descending Sort)
 943  */
 944 static inline void btrfs_descending_sort_devices(
 945                                         struct btrfs_device_info *devices,
 946                                         size_t nr_devices)
 947 {
 948         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
 949              btrfs_cmp_device_free_bytes, NULL);
 950 }
 951
 952 /*
 953  * The helper to calc the free space on the devices that can be used to store
 954  * file data.
 955  */
 956 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
 957 {
 958         struct btrfs_fs_info *fs_info = root->fs_info;
 959         struct btrfs_device_info *devices_info;
 960         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 961         struct btrfs_device *device;
 962         u64 skip_space;
 963         u64 type;
 964         u64 avail_space;
 965         u64 used_space;
 966         u64 min_stripe_size;
 967         int min_stripes = 1;
 968         int i = 0, nr_devices;
 969         int ret;
 970
 971         nr_devices = fs_info->fs_devices->rw_devices;
 972         BUG_ON(!nr_devices);
 973
 974         devices_info = kmalloc(sizeof(*devices_info) * nr_devices,
 975                                GFP_NOFS);
 976         if (!devices_info)
 977                 return -ENOMEM;
 978
 979         /* calc min stripe number for data space alloction */
 980         type = btrfs_get_alloc_profile(root, 1);
 981         if (type & BTRFS_BLOCK_GROUP_RAID0)
 982                 min_stripes = 2;
 983         else if (type & BTRFS_BLOCK_GROUP_RAID1)
 984                 min_stripes = 2;
 985         else if (type & BTRFS_BLOCK_GROUP_RAID10)
 986                 min_stripes = 4;
 987
 988         if (type & BTRFS_BLOCK_GROUP_DUP)
 989                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
 990         else
 991                 min_stripe_size = BTRFS_STRIPE_LEN;
 992
 993         list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) {
 994                 if (!device->in_fs_metadata)
 995                         continue;
 996
 997                 avail_space = device->total_bytes - device->bytes_used;
 998
 999                 /* align with stripe_len */
1000                 do_div(avail_space, BTRFS_STRIPE_LEN);
1001                 avail_space *= BTRFS_STRIPE_LEN;
1002
1003                 /*
1004                  * In order to avoid overwritting the superblock on the drive,
1005                  * btrfs starts at an offset of at least 1MB when doing chunk
1006                  * allocation.
1007                  */
1008                 skip_space = 1024 * 1024;
1009
1010                 /* user can set the offset in fs_info->alloc_start. */
1011                 if (fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1012                     device->total_bytes)
1013                         skip_space = max(fs_info->alloc_start, skip_space);
1014
1015                 /*
1016                  * btrfs can not use the free space in [0, skip_space - 1],
1017                  * we must subtract it from the total. In order to implement
1018                  * it, we account the used space in this range first.
1019                  */
1020                 ret = btrfs_account_dev_extents_size(device, 0, skip_space - 1,
1021                                                      &used_space);
1022                 if (ret) {
1023                         kfree(devices_info);
1024                         return ret;
1025                 }
1026
1027                 /* calc the free space in [0, skip_space - 1] */
1028                 skip_space -= used_space;
1029
1030                 /*
1031                  * we can use the free space in [0, skip_space - 1], subtract
1032                  * it from the total.
1033                  */
1034                 if (avail_space && avail_space >= skip_space)
1035                         avail_space -= skip_space;
1036                 else
1037                         avail_space = 0;
1038
1039                 if (avail_space < min_stripe_size)
1040                         continue;
1041
1042                 devices_info[i].dev = device;
1043                 devices_info[i].max_avail = avail_space;
1044
1045                 i++;
1046         }
1047
1048         nr_devices = i;
1049
1050         btrfs_descending_sort_devices(devices_info, nr_devices);
1051
1052         i = nr_devices - 1;
1053         avail_space = 0;
1054         while (nr_devices >= min_stripes) {
1055                 if (devices_info[i].max_avail >= min_stripe_size) {
1056                         int j;
1057                         u64 alloc_size;
1058
1059                         avail_space += devices_info[i].max_avail * min_stripes;
1060                         alloc_size = devices_info[i].max_avail;
1061                         for (j = i + 1 - min_stripes; j <= i; j++)
1062                                 devices_info[j].max_avail -= alloc_size;
1063                 }
1064                 i--;
1065                 nr_devices--;
1066         }
1067
1068         kfree(devices_info);
1069         *free_bytes = avail_space;
1070         return 0;
1071 }
1072
1073 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1074 {
1075         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
1076         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
1077         struct list_head *head = &root->fs_info->space_info;
1078         struct btrfs_space_info *found;
1079         u64 total_used = 0;
1080         u64 total_free_data = 0;
1081         int bits = dentry->d_sb->s_blocksize_bits;
1082         __be32 *fsid = (__be32 *)root->fs_info->fsid;
1083         int ret;
1084
1085         /* holding chunk_muext to avoid allocating new chunks */
1086         mutex_lock(&root->fs_info->chunk_mutex);
1087         rcu_read_lock();
1088         list_for_each_entry_rcu(found, head, list) {
1089                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
1090                         total_free_data += found->disk_total - found->disk_used;
1091                         total_free_data -=
1092                                 btrfs_account_ro_block_groups_free_space(found);
1093                 }
1094
1095                 total_used += found->disk_used;
1096         }
1097         rcu_read_unlock();
1098
1099         buf->f_namelen = BTRFS_NAME_LEN;
1100         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
1101         buf->f_bfree = buf->f_blocks - (total_used >> bits);
1102         buf->f_bsize = dentry->d_sb->s_blocksize;
1103         buf->f_type = BTRFS_SUPER_MAGIC;
1104         buf->f_bavail = total_free_data;
1105         ret = btrfs_calc_avail_data_space(root, &total_free_data);
1106         if (ret) {
1107                 mutex_unlock(&root->fs_info->chunk_mutex);
1108                 return ret;
1109         }
1110         buf->f_bavail += total_free_data;
1111         buf->f_bavail = buf->f_bavail >> bits;
1112         mutex_unlock(&root->fs_info->chunk_mutex);
1113
1114         /* We treat it as constant endianness (it doesn't matter _which_)
1115            because we want the fsid to come out the same whether mounted
1116            on a big-endian or little-endian host */
1117         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
1118         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
1119         /* Mask in the root object ID too, to disambiguate subvols */
1120         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
1121         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
1122
1123         return 0;
1124 }
1125
1126 static struct file_system_type btrfs_fs_type = {
1127         .owner          = THIS_MODULE,
1128         .name           = "btrfs",
1129         .mount          = btrfs_mount,
1130         .kill_sb        = kill_anon_super,
1131         .fs_flags       = FS_REQUIRES_DEV,
1132 };
1133
1134 /*
1135  * used by btrfsctl to scan devices when no FS is mounted
1136  */
1137 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
1138                                 unsigned long arg)
1139 {
1140         struct btrfs_ioctl_vol_args *vol;
1141         struct btrfs_fs_devices *fs_devices;
1142         int ret = -ENOTTY;
1143
1144         if (!capable(CAP_SYS_ADMIN))
1145                 return -EPERM;
1146
1147         vol = memdup_user((void __user *)arg, sizeof(*vol));
1148         if (IS_ERR(vol))
1149                 return PTR_ERR(vol);
1150
1151         switch (cmd) {
1152         case BTRFS_IOC_SCAN_DEV:
1153                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1154                                             &btrfs_fs_type, &fs_devices);
1155                 break;
1156         }
1157
1158         kfree(vol);
1159         return ret;
1160 }
1161
1162 static int btrfs_freeze(struct super_block *sb)
1163 {
1164         struct btrfs_root *root = btrfs_sb(sb);
1165         mutex_lock(&root->fs_info->transaction_kthread_mutex);
1166         mutex_lock(&root->fs_info->cleaner_mutex);
1167         return 0;
1168 }
1169
1170 static int btrfs_unfreeze(struct super_block *sb)
1171 {
1172         struct btrfs_root *root = btrfs_sb(sb);
1173         mutex_unlock(&root->fs_info->cleaner_mutex);
1174         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
1175         return 0;
1176 }
1177
1178 static const struct super_operations btrfs_super_ops = {
1179         .drop_inode     = btrfs_drop_inode,
1180         .evict_inode    = btrfs_evict_inode,
1181         .put_super      = btrfs_put_super,
1182         .sync_fs        = btrfs_sync_fs,
1183         .show_options   = btrfs_show_options,
1184         .write_inode    = btrfs_write_inode,
1185         .dirty_inode    = btrfs_dirty_inode,
1186         .alloc_inode    = btrfs_alloc_inode,
1187         .destroy_inode  = btrfs_destroy_inode,
1188         .statfs         = btrfs_statfs,
1189         .remount_fs     = btrfs_remount,
1190         .freeze_fs      = btrfs_freeze,
1191         .unfreeze_fs    = btrfs_unfreeze,
1192 };
1193
1194 static const struct file_operations btrfs_ctl_fops = {
1195         .unlocked_ioctl  = btrfs_control_ioctl,
1196         .compat_ioctl = btrfs_control_ioctl,
1197         .owner   = THIS_MODULE,
1198         .llseek = noop_llseek,
1199 };
1200
1201 static struct miscdevice btrfs_misc = {
1202         .minor          = BTRFS_MINOR,
1203         .name           = "btrfs-control",
1204         .fops           = &btrfs_ctl_fops
1205 };
1206
1207 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
1208 MODULE_ALIAS("devname:btrfs-control");
1209
1210 static int btrfs_interface_init(void)
1211 {
1212         return misc_register(&btrfs_misc);
1213 }
1214
1215 static void btrfs_interface_exit(void)
1216 {
1217         if (misc_deregister(&btrfs_misc) < 0)
1218                 printk(KERN_INFO "misc_deregister failed for control device");
1219 }
1220
1221 static int __init init_btrfs_fs(void)
1222 {
1223         int err;
1224
1225         err = btrfs_init_sysfs();
1226         if (err)
1227                 return err;
1228
1229         err = btrfs_init_compress();
1230         if (err)
1231                 goto free_sysfs;
1232
1233         err = btrfs_init_cachep();
1234         if (err)
1235                 goto free_compress;
1236
1237         err = extent_io_init();
1238         if (err)
1239                 goto free_cachep;
1240
1241         err = extent_map_init();
1242         if (err)
1243                 goto free_extent_io;
1244
1245         err = btrfs_delayed_inode_init();
1246         if (err)
1247                 goto free_extent_map;
1248
1249         err = btrfs_interface_init();
1250         if (err)
1251                 goto free_delayed_inode;
1252
1253         err = register_filesystem(&btrfs_fs_type);
1254         if (err)
1255                 goto unregister_ioctl;
1256
1257         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
1258         return 0;
1259
1260 unregister_ioctl:
1261         btrfs_interface_exit();
1262 free_delayed_inode:
1263         btrfs_delayed_inode_exit();
1264 free_extent_map:
1265         extent_map_exit();
1266 free_extent_io:
1267         extent_io_exit();
1268 free_cachep:
1269         btrfs_destroy_cachep();
1270 free_compress:
1271         btrfs_exit_compress();
1272 free_sysfs:
1273         btrfs_exit_sysfs();
1274         return err;
1275 }
1276
1277 static void __exit exit_btrfs_fs(void)
1278 {
1279         btrfs_destroy_cachep();
1280         btrfs_delayed_inode_exit();
1281         extent_map_exit();
1282         extent_io_exit();
1283         btrfs_interface_exit();
1284         unregister_filesystem(&btrfs_fs_type);
1285         btrfs_exit_sysfs();
1286         btrfs_cleanup_fs_uuids();
1287         btrfs_exit_compress();
1288 }
1289
1290 module_init(init_btrfs_fs)
1291 module_exit(exit_btrfs_fs)
1292
1293 MODULE_LICENSE("GPL");