inode.c

   1 /*
   2  * Copyright (C) 2014 Fujitsu.  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 /*
  20  * Unlike inode.c in kernel, which can use most of the kernel infrastructure
  21  * like inode/dentry things, in user-land, we can only use inode number to
  22  * do directly operation on extent buffer, which may cause extra searching,
  23  * but should not be a huge problem since progs is less performance sensitive.
  24  */
  25 #include <sys/stat.h>
  26
  27 #include "ctree.h"
  28 #include "transaction.h"
  29 #include "disk-io.h"
  30 #include "time.h"
  31 #include "messages.h"
  32
  33 /*
  34  * Find a free inode index for later btrfs_add_link().
  35  * Currently just search from the largest dir_index and +1.
  36  */
  37 static int btrfs_find_free_dir_index(struct btrfs_root *root, u64 dir_ino,
  38                                      u64 *ret_ino)
  39 {
  40         struct btrfs_path *path;
  41         struct btrfs_key key;
  42         struct btrfs_key found_key;
  43         u64 ret_val = 2;
  44         int ret = 0;
  45
  46         if (!ret_ino)
  47                 return 0;
  48
  49         path = btrfs_alloc_path();
  50         if (!path)
  51                 return -ENOMEM;
  52
  53         key.objectid = dir_ino;
  54         key.type = BTRFS_DIR_INDEX_KEY;
  55         key.offset = (u64)-1;
  56
  57         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  58         if (ret < 0)
  59                 goto out;
  60         ret = 0;
  61         if (path->slots[0] == 0) {
  62                 ret = btrfs_prev_leaf(root, path);
  63                 if (ret < 0)
  64                         goto out;
  65                 if (ret > 0) {
  66                         /*
  67                          * This shouldn't happen since there must be a leaf
  68                          * containing the DIR_ITEM.
  69                          * Can only happen when the previous leaf is corrupted.
  70                          */
  71                         ret = -EIO;
  72                         goto out;
  73                 }
  74         } else {
  75                 path->slots[0]--;
  76         }
  77         btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
  78         if (found_key.objectid != dir_ino ||
  79             found_key.type != BTRFS_DIR_INDEX_KEY)
  80                 goto out;
  81         ret_val = found_key.offset + 1;
  82 out:
  83         btrfs_free_path(path);
  84         if (ret == 0)
  85                 *ret_ino = ret_val;
  86         return ret;
  87 }
  88
  89 /* Check the dir_item/index conflicts before insert */
  90 int check_dir_conflict(struct btrfs_root *root, char *name, int namelen,
  91                        u64 dir, u64 index)
  92 {
  93         struct btrfs_path *path;
  94         struct btrfs_key key;
  95         struct btrfs_inode_item *inode_item;
  96         struct btrfs_dir_item *dir_item;
  97         int ret = 0;
  98
  99         path = btrfs_alloc_path();
 100         if (!path)
 101                 return -ENOMEM;
 102
 103         /* Given dir exists? */
 104         key.objectid = dir;
 105         key.type = BTRFS_INODE_ITEM_KEY;
 106         key.offset = 0;
 107         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 108         if (ret < 0)
 109                 goto out;
 110         if (ret > 0) {
 111                 ret = -ENOENT;
 112                 goto out;
 113         }
 114
 115         /* Is it a dir? */
 116         inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 117                                     struct btrfs_inode_item);
 118         if (!(btrfs_inode_mode(path->nodes[0], inode_item) & S_IFDIR)) {
 119                 ret = -ENOTDIR;
 120                 goto out;
 121         }
 122         btrfs_release_path(path);
 123
 124         /* Name conflicting? */
 125         dir_item = btrfs_lookup_dir_item(NULL, root, path, dir, name,
 126                                          namelen, 0);
 127         if (IS_ERR(dir_item)) {
 128                 ret = PTR_ERR(dir_item);
 129                 goto out;
 130         }
 131         if (dir_item) {
 132                 ret = -EEXIST;
 133                 goto out;
 134         }
 135         btrfs_release_path(path);
 136
 137         /* Index conflicting? */
 138         dir_item = btrfs_lookup_dir_index(NULL, root, path, dir, name,
 139                                           namelen, index, 0);
 140         if (IS_ERR(dir_item) && PTR_ERR(dir_item) == -ENOENT)
 141                 dir_item = NULL;
 142         if (IS_ERR(dir_item)) {
 143                 ret = PTR_ERR(dir_item);
 144                 goto out;
 145         }
 146         if (dir_item) {
 147                 ret = -EEXIST;
 148                 goto out;
 149         }
 150
 151 out:
 152         btrfs_free_path(path);
 153         return ret;
 154 }
 155
 156 /*
 157  * Add dir_item/index for 'parent_ino' if add_backref is true, also insert a
 158  * backref from the ino to parent dir and update the nlink(Kernel version does
 159  * not do this thing)
 160  *
 161  * Currently only supports adding link from an inode to another inode.
 162  */
 163 int btrfs_add_link(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 164                    u64 ino, u64 parent_ino, char *name, int namelen,
 165                    u8 type, u64 *index, int add_backref, int ignore_existed)
 166 {
 167         struct btrfs_path *path;
 168         struct btrfs_key key;
 169         struct btrfs_inode_item *inode_item;
 170         u32 nlink;
 171         u64 inode_size;
 172         u64 ret_index = 0;
 173         int ret = 0;
 174
 175         path = btrfs_alloc_path();
 176         if (!path)
 177                 return -ENOMEM;
 178
 179         if (index && *index) {
 180                 ret_index = *index;
 181         } else {
 182                 ret = btrfs_find_free_dir_index(root, parent_ino, &ret_index);
 183                 if (ret < 0)
 184                         goto out;
 185         }
 186
 187         ret = check_dir_conflict(root, name, namelen, parent_ino, ret_index);
 188         if (ret < 0 && !(ignore_existed && ret == -EEXIST))
 189                 goto out;
 190
 191         /* Add inode ref */
 192         if (add_backref) {
 193                 ret = btrfs_insert_inode_ref(trans, root, name, namelen,
 194                                              ino, parent_ino, ret_index);
 195                 if (ret < 0 && !(ignore_existed && ret == -EEXIST))
 196                         goto out;
 197
 198                 /* do not update nlinks if existed */
 199                 if (!ret) {
 200                         /* Update nlinks for the inode */
 201                         key.objectid = ino;
 202                         key.type = BTRFS_INODE_ITEM_KEY;
 203                         key.offset = 0;
 204                         ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 205                         if (ret) {
 206                                 if (ret > 0)
 207                                         ret = -ENOENT;
 208                                 goto out;
 209                         }
 210                         inode_item = btrfs_item_ptr(path->nodes[0],
 211                                     path->slots[0], struct btrfs_inode_item);
 212                         nlink = btrfs_inode_nlink(path->nodes[0], inode_item);
 213                         nlink++;
 214                         btrfs_set_inode_nlink(path->nodes[0], inode_item,
 215                                               nlink);
 216                         btrfs_mark_buffer_dirty(path->nodes[0]);
 217                         btrfs_release_path(path);
 218                 }
 219         }
 220
 221         /* Add dir_item and dir_index */
 222         key.objectid = ino;
 223         key.type = BTRFS_INODE_ITEM_KEY;
 224         key.offset = 0;
 225         ret = btrfs_insert_dir_item(trans, root, name, namelen, parent_ino,
 226                                     &key, type, ret_index);
 227         if (ret < 0)
 228                 goto out;
 229
 230         /* Update inode size of the parent inode */
 231         key.objectid = parent_ino;
 232         key.type = BTRFS_INODE_ITEM_KEY;
 233         key.offset = 0;
 234         ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 235         if (ret)
 236                 goto out;
 237         inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 238                                     struct btrfs_inode_item);
 239         inode_size = btrfs_inode_size(path->nodes[0], inode_item);
 240         inode_size += namelen * 2;
 241         btrfs_set_inode_size(path->nodes[0], inode_item, inode_size);
 242         btrfs_mark_buffer_dirty(path->nodes[0]);
 243         btrfs_release_path(path);
 244
 245 out:
 246         btrfs_free_path(path);
 247         if (ret == 0 && index)
 248                 *index = ret_index;
 249         return ret;
 250 }
 251
 252 int btrfs_add_orphan_item(struct btrfs_trans_handle *trans,
 253                           struct btrfs_root *root, struct btrfs_path *path,
 254                           u64 ino)
 255 {
 256         struct btrfs_key key;
 257
 258         key.objectid = BTRFS_ORPHAN_OBJECTID;
 259         key.type = BTRFS_ORPHAN_ITEM_KEY;
 260         key.offset = ino;
 261
 262         return btrfs_insert_empty_item(trans, root, path, &key, 0);
 263 }
 264
 265 /*
 266  * Unlink an inode, which will remove its backref and corresponding dir_index/
 267  * dir_item if any of them exists.
 268  *
 269  * If an inode's nlink is reduced to 0 and 'add_orphan' is true, it will be
 270  * added to orphan inode and waiting to be deleted by next kernel mount.
 271  */
 272 int btrfs_unlink(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 273                  u64 ino, u64 parent_ino, u64 index, const char *name,
 274                  int namelen, int add_orphan)
 275 {
 276         struct btrfs_path *path;
 277         struct btrfs_key key;
 278         struct btrfs_inode_item *inode_item;
 279         struct btrfs_inode_ref *inode_ref;
 280         struct btrfs_dir_item *dir_item;
 281         u64 inode_size;
 282         u32 nlinks;
 283         int del_inode_ref = 0;
 284         int del_dir_item = 0;
 285         int del_dir_index = 0;
 286         int ret = 0;
 287
 288         path = btrfs_alloc_path();
 289         if (!path)
 290                 return -ENOMEM;
 291
 292         /* check the ref and backref exists */
 293         inode_ref = btrfs_lookup_inode_ref(trans, root, path, name, namelen,
 294                                            ino, parent_ino, 0);
 295         if (IS_ERR(inode_ref)) {
 296                 ret = PTR_ERR(inode_ref);
 297                 goto out;
 298         }
 299         if (inode_ref)
 300                 del_inode_ref = 1;
 301         btrfs_release_path(path);
 302
 303         dir_item = btrfs_lookup_dir_item(NULL, root, path, parent_ino,
 304                                          name, namelen, 0);
 305         if (IS_ERR(dir_item)) {
 306                 ret = PTR_ERR(dir_item);
 307                 goto out;
 308         }
 309         if (dir_item)
 310                 del_dir_item = 1;
 311         btrfs_release_path(path);
 312
 313         dir_item = btrfs_lookup_dir_index(NULL, root, path, parent_ino,
 314                                           name, namelen, index, 0);
 315         /*
 316          * Since lookup_dir_index() will return -ENOENT when not found,
 317          * we need to do extra check.
 318          */
 319         if (IS_ERR(dir_item) && PTR_ERR(dir_item) == -ENOENT)
 320                 dir_item = NULL;
 321         if (IS_ERR(dir_item)) {
 322                 ret = PTR_ERR(dir_item);
 323                 goto out;
 324         }
 325         if (dir_item)
 326                 del_dir_index = 1;
 327         btrfs_release_path(path);
 328
 329         if (!del_inode_ref && !del_dir_item && !del_dir_index) {
 330                 /* All not found, shouldn't happen */
 331                 ret = -ENOENT;
 332                 goto out;
 333         }
 334
 335         if (del_inode_ref) {
 336                 /* Only decrease nlink when deleting inode_ref */
 337                 key.objectid = ino;
 338                 key.type = BTRFS_INODE_ITEM_KEY;
 339                 key.offset = 0;
 340                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 341                 if (ret) {
 342                         if (ret > 0)
 343                                 ret = -ENOENT;
 344                         goto out;
 345                 }
 346                 inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 347                                             struct btrfs_inode_item);
 348                 nlinks = btrfs_inode_nlink(path->nodes[0], inode_item);
 349                 if (nlinks > 0)
 350                         nlinks--;
 351                 btrfs_set_inode_nlink(path->nodes[0], inode_item, nlinks);
 352                 btrfs_mark_buffer_dirty(path->nodes[0]);
 353                 btrfs_release_path(path);
 354
 355                 /* For nlinks == 0, add it to orphan list if needed */
 356                 if (nlinks == 0 && add_orphan) {
 357                         ret = btrfs_add_orphan_item(trans, root, path, ino);
 358                         if (ret < 0)
 359                                 goto out;
 360                         btrfs_mark_buffer_dirty(path->nodes[0]);
 361                         btrfs_release_path(path);
 362                 }
 363
 364                 ret = btrfs_del_inode_ref(trans, root, name, namelen, ino,
 365                                           parent_ino, &index);
 366                 if (ret < 0)
 367                         goto out;
 368         }
 369
 370         if (del_dir_index) {
 371                 dir_item = btrfs_lookup_dir_index(trans, root, path,
 372                                                   parent_ino, name, namelen,
 373                                                   index, -1);
 374                 if (IS_ERR(dir_item)) {
 375                         ret = PTR_ERR(dir_item);
 376                         goto out;
 377                 }
 378                 if (!dir_item) {
 379                         ret = -ENOENT;
 380                         goto out;
 381                 }
 382                 ret = btrfs_delete_one_dir_name(trans, root, path, dir_item);
 383                 if (ret)
 384                         goto out;
 385                 btrfs_release_path(path);
 386
 387                 /* Update inode size of the parent inode */
 388                 key.objectid = parent_ino;
 389                 key.type = BTRFS_INODE_ITEM_KEY;
 390                 key.offset = 0;
 391                 ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 392                 if (ret)
 393                         goto out;
 394                 inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 395                                             struct btrfs_inode_item);
 396                 inode_size = btrfs_inode_size(path->nodes[0], inode_item);
 397                 if (inode_size >= namelen)
 398                         inode_size -= namelen;
 399                 btrfs_set_inode_size(path->nodes[0], inode_item, inode_size);
 400                 btrfs_mark_buffer_dirty(path->nodes[0]);
 401                 btrfs_release_path(path);
 402         }
 403
 404         if (del_dir_item) {
 405                 dir_item = btrfs_lookup_dir_item(trans, root, path, parent_ino,
 406                                                  name, namelen, -1);
 407                 if (IS_ERR(dir_item)) {
 408                         ret = PTR_ERR(dir_item);
 409                         goto out;
 410                 }
 411                 if (!dir_item) {
 412                         ret = -ENOENT;
 413                         goto out;
 414                 }
 415                 ret = btrfs_delete_one_dir_name(trans, root, path, dir_item);
 416                 if (ret < 0)
 417                         goto out;
 418                 btrfs_release_path(path);
 419
 420                 /* Update inode size of the parent inode */
 421                 key.objectid = parent_ino;
 422                 key.type = BTRFS_INODE_ITEM_KEY;
 423                 key.offset = 0;
 424                 ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 425                 if (ret)
 426                         goto out;
 427                 inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 428                                             struct btrfs_inode_item);
 429                 inode_size = btrfs_inode_size(path->nodes[0], inode_item);
 430                 if (inode_size >= namelen)
 431                         inode_size -= namelen;
 432                 btrfs_set_inode_size(path->nodes[0], inode_item, inode_size);
 433                 btrfs_mark_buffer_dirty(path->nodes[0]);
 434                 btrfs_release_path(path);
 435         }
 436
 437 out:
 438         btrfs_free_path(path);
 439         return ret;
 440 }
 441
 442 /* Fill inode item with 'mode'. Uid/gid to root/root */
 443 static void fill_inode_item(struct btrfs_trans_handle *trans,
 444                             struct btrfs_inode_item *inode_item,
 445                             u32 mode, u32 nlink)
 446 {
 447         time_t now = time(NULL);
 448
 449         btrfs_set_stack_inode_generation(inode_item, trans->transid);
 450         btrfs_set_stack_inode_uid(inode_item, 0);
 451         btrfs_set_stack_inode_gid(inode_item, 0);
 452         btrfs_set_stack_inode_size(inode_item, 0);
 453         btrfs_set_stack_inode_mode(inode_item, mode);
 454         btrfs_set_stack_inode_nlink(inode_item, nlink);
 455         btrfs_set_stack_timespec_sec(&inode_item->atime, now);
 456         btrfs_set_stack_timespec_nsec(&inode_item->atime, 0);
 457         btrfs_set_stack_timespec_sec(&inode_item->mtime, now);
 458         btrfs_set_stack_timespec_nsec(&inode_item->mtime, 0);
 459         btrfs_set_stack_timespec_sec(&inode_item->ctime, now);
 460         btrfs_set_stack_timespec_nsec(&inode_item->ctime, 0);
 461 }
 462
 463 /*
 464  * Unlike kernel btrfs_new_inode(), we only create the INODE_ITEM, without
 465  * its backref.
 466  * The backref is added by btrfs_add_link().
 467  */
 468 int btrfs_new_inode(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 469                 u64 ino, u32 mode)
 470 {
 471         struct btrfs_inode_item inode_item = {0};
 472         int ret = 0;
 473
 474         fill_inode_item(trans, &inode_item, mode, 0);
 475         ret = btrfs_insert_inode(trans, root, ino, &inode_item);
 476         return ret;
 477 }
 478
 479 /*
 480  * Change inode flags to given value
 481  */
 482 int btrfs_change_inode_flags(struct btrfs_trans_handle *trans,
 483                              struct btrfs_root *root, u64 ino, u64 flags)
 484 {
 485         struct btrfs_inode_item *item;
 486         struct btrfs_path *path;
 487         struct btrfs_key key;
 488         int ret;
 489
 490         path = btrfs_alloc_path();
 491         if (!path)
 492                 return -ENOMEM;
 493
 494         key.objectid = ino;
 495         key.type = BTRFS_INODE_ITEM_KEY;
 496         key.offset = 0;
 497
 498         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 499         if (ret > 0) {
 500                 ret = -ENOENT;
 501                 goto out;
 502         }
 503         if (ret < 0)
 504                 goto out;
 505
 506         item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 507                               struct btrfs_inode_item);
 508         btrfs_set_inode_flags(path->nodes[0], item, flags);
 509         btrfs_mark_buffer_dirty(path->nodes[0]);
 510 out:
 511         btrfs_free_path(path);
 512         return ret;
 513 }
 514
 515 /*
 516  * Make a dir under the parent inode 'parent_ino' with 'name'
 517  * and 'mode', The owner will be root/root.
 518  */
 519 int btrfs_mkdir(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 520                 char *name, int namelen, u64 parent_ino, u64 *ino, int mode)
 521 {
 522         struct btrfs_dir_item *dir_item;
 523         struct btrfs_path *path;
 524         u64 ret_ino = 0;
 525         int ret = 0;
 526
 527         path = btrfs_alloc_path();
 528         if (!path)
 529                 return -ENOMEM;
 530
 531         if (ino && *ino)
 532                 ret_ino = *ino;
 533
 534         dir_item = btrfs_lookup_dir_item(NULL, root, path, parent_ino,
 535                                          name, namelen, 0);
 536         if (IS_ERR(dir_item)) {
 537                 ret = PTR_ERR(dir_item);
 538                 goto out;
 539         }
 540
 541         if (dir_item) {
 542                 struct btrfs_key found_key;
 543
 544                 /*
 545                  * Already have conflicting name, check if it is a dir.
 546                  * Either way, no need to continue.
 547                  */
 548                 btrfs_dir_item_key_to_cpu(path->nodes[0], dir_item, &found_key);
 549                 ret_ino = found_key.objectid;
 550                 if (btrfs_dir_type(path->nodes[0], dir_item) != BTRFS_FT_DIR)
 551                         ret = -EEXIST;
 552                 goto out;
 553         }
 554
 555         if (!ret_ino)
 556                 /*
 557                  * This is *UNSAFE* if some leaf is corrupted,
 558                  * only used as a fallback method. Caller should either
 559                  * ensure the fs is OK or pass ino with unused inode number.
 560                  */
 561                 ret = btrfs_find_free_objectid(NULL, root, parent_ino,
 562                                                &ret_ino);
 563         if (ret)
 564                 goto out;
 565         ret = btrfs_new_inode(trans, root, ret_ino, mode | S_IFDIR);
 566         if (ret)
 567                 goto out;
 568         ret = btrfs_add_link(trans, root, ret_ino, parent_ino, name, namelen,
 569                              BTRFS_FT_DIR, NULL, 1, 0);
 570         if (ret)
 571                 goto out;
 572 out:
 573         btrfs_free_path(path);
 574         if (ret == 0 && ino)
 575                 *ino = ret_ino;
 576         return ret;
 577 }
 578
 579 struct btrfs_root *btrfs_mksubvol(struct btrfs_root *root,
 580                                   const char *base, u64 root_objectid,
 581                                   bool convert)
 582 {
 583         struct btrfs_trans_handle *trans;
 584         struct btrfs_fs_info *fs_info = root->fs_info;
 585         struct btrfs_root *tree_root = fs_info->tree_root;
 586         struct btrfs_root *new_root = NULL;
 587         struct btrfs_path path;
 588         struct btrfs_inode_item *inode_item;
 589         struct extent_buffer *leaf;
 590         struct btrfs_key key;
 591         u64 dirid = btrfs_root_dirid(&root->root_item);
 592         u64 index = 2;
 593         char buf[BTRFS_NAME_LEN + 1]; /* for snprintf null */
 594         int len;
 595         int i;
 596         int ret;
 597
 598         len = strlen(base);
 599         if (len == 0 || len > BTRFS_NAME_LEN)
 600                 return NULL;
 601
 602         btrfs_init_path(&path);
 603         key.objectid = dirid;
 604         key.type = BTRFS_DIR_INDEX_KEY;
 605         key.offset = (u64)-1;
 606
 607         ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
 608         if (ret <= 0) {
 609                 error("search for DIR_INDEX dirid %llu failed: %d",
 610                                 (unsigned long long)dirid, ret);
 611                 goto fail;
 612         }
 613
 614         if (path.slots[0] > 0) {
 615                 path.slots[0]--;
 616                 btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
 617                 if (key.objectid == dirid && key.type == BTRFS_DIR_INDEX_KEY)
 618                         index = key.offset + 1;
 619         }
 620         btrfs_release_path(&path);
 621
 622         trans = btrfs_start_transaction(root, 1);
 623         if (IS_ERR(trans)) {
 624                 error("unable to start transaction");
 625                 goto fail;
 626         }
 627
 628         key.objectid = dirid;
 629         key.offset = 0;
 630         key.type =  BTRFS_INODE_ITEM_KEY;
 631
 632         ret = btrfs_lookup_inode(trans, root, &path, &key, 1);
 633         if (ret) {
 634                 error("search for INODE_ITEM %llu failed: %d",
 635                                 (unsigned long long)dirid, ret);
 636                 goto fail;
 637         }
 638         leaf = path.nodes[0];
 639         inode_item = btrfs_item_ptr(leaf, path.slots[0],
 640                                     struct btrfs_inode_item);
 641
 642         key.objectid = root_objectid;
 643         key.offset = (u64)-1;
 644         key.type = BTRFS_ROOT_ITEM_KEY;
 645
 646         memcpy(buf, base, len);
 647         if (convert) {
 648                 for (i = 0; i < 1024; i++) {
 649                         ret = btrfs_insert_dir_item(trans, root, buf, len,
 650                                         dirid, &key, BTRFS_FT_DIR, index);
 651                         if (ret != -EEXIST)
 652                                 break;
 653                         len = snprintf(buf, ARRAY_SIZE(buf), "%s%d", base, i);
 654                         if (len < 1 || len > BTRFS_NAME_LEN) {
 655                                 ret = -EINVAL;
 656                                 break;
 657                         }
 658                 }
 659         } else {
 660                 ret = btrfs_insert_dir_item(trans, root, buf, len, dirid, &key,
 661                                             BTRFS_FT_DIR, index);
 662         }
 663         if (ret)
 664                 goto fail;
 665
 666         btrfs_set_inode_size(leaf, inode_item, len * 2 +
 667                              btrfs_inode_size(leaf, inode_item));
 668         btrfs_mark_buffer_dirty(leaf);
 669         btrfs_release_path(&path);
 670
 671         /* add the backref first */
 672         ret = btrfs_add_root_ref(trans, tree_root, root_objectid,
 673                                  BTRFS_ROOT_BACKREF_KEY,
 674                                  root->root_key.objectid,
 675                                  dirid, index, buf, len);
 676         if (ret) {
 677                 error("unable to add root backref for %llu: %d",
 678                                 root->root_key.objectid, ret);
 679                 goto fail;
 680         }
 681
 682         /* now add the forward ref */
 683         ret = btrfs_add_root_ref(trans, tree_root, root->root_key.objectid,
 684                                  BTRFS_ROOT_REF_KEY, root_objectid,
 685                                  dirid, index, buf, len);
 686         if (ret) {
 687                 error("unable to add root ref for %llu: %d",
 688                                 root->root_key.objectid, ret);
 689                 goto fail;
 690         }
 691
 692         ret = btrfs_commit_transaction(trans, root);
 693         if (ret) {
 694                 error("transaction commit failed: %d", ret);
 695                 goto fail;
 696         }
 697
 698         new_root = btrfs_read_fs_root(fs_info, &key);
 699         if (IS_ERR(new_root)) {
 700                 error("unable to fs read root: %lu", PTR_ERR(new_root));
 701                 new_root = NULL;
 702         }
 703 fail:
 704         btrfs_init_path(&path);
 705         return new_root;
 706 }