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