ctree.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 #include "ctree.h"
  19 #include "disk-io.h"
  20 #include "transaction.h"
  21 #include "print-tree.h"
  22
  23 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  24                       *root, struct btrfs_path *path, int level);
  25 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  26                       *root, struct btrfs_key *ins_key,
  27                       struct btrfs_path *path, int data_size, int extend);
  28 static int push_node_left(struct btrfs_trans_handle *trans,
  29                           struct btrfs_root *root, struct extent_buffer *dst,
  30                           struct extent_buffer *src);
  31 static int balance_node_right(struct btrfs_trans_handle *trans,
  32                               struct btrfs_root *root,
  33                               struct extent_buffer *dst_buf,
  34                               struct extent_buffer *src_buf);
  35 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  36                    struct btrfs_path *path, int level, int slot);
  37
  38 inline void btrfs_init_path(struct btrfs_path *p)
  39 {
  40         memset(p, 0, sizeof(*p));
  41 }
  42
  43 struct btrfs_path *btrfs_alloc_path(void)
  44 {
  45         struct btrfs_path *path;
  46         path = kmalloc(sizeof(struct btrfs_path), GFP_NOFS);
  47         if (path) {
  48                 btrfs_init_path(path);
  49                 path->reada = 0;
  50         }
  51         return path;
  52 }
  53
  54 void btrfs_free_path(struct btrfs_path *p)
  55 {
  56         btrfs_release_path(NULL, p);
  57         kfree(p);
  58 }
  59
  60 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
  61 {
  62         int i;
  63         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  64                 if (!p->nodes[i])
  65                         break;
  66                 free_extent_buffer(p->nodes[i]);
  67         }
  68         memset(p, 0, sizeof(*p));
  69 }
  70
  71 static void add_root_to_dirty_list(struct btrfs_root *root)
  72 {
  73         if (root->track_dirty && list_empty(&root->dirty_list)) {
  74                 list_add(&root->dirty_list,
  75                          &root->fs_info->dirty_cowonly_roots);
  76         }
  77 }
  78
  79 int btrfs_copy_root(struct btrfs_trans_handle *trans,
  80                       struct btrfs_root *root,
  81                       struct extent_buffer *buf,
  82                       struct extent_buffer **cow_ret, u64 new_root_objectid)
  83 {
  84         struct extent_buffer *cow;
  85         u32 nritems;
  86         int ret = 0;
  87         int level;
  88         struct btrfs_key first_key;
  89         struct btrfs_root *new_root;
  90
  91         new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
  92         if (!new_root)
  93                 return -ENOMEM;
  94
  95         memcpy(new_root, root, sizeof(*new_root));
  96         new_root->root_key.objectid = new_root_objectid;
  97
  98         WARN_ON(root->ref_cows && trans->transid !=
  99                 root->fs_info->running_transaction->transid);
 100         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 101
 102         level = btrfs_header_level(buf);
 103         nritems = btrfs_header_nritems(buf);
 104         if (nritems) {
 105                 if (level == 0)
 106                         btrfs_item_key_to_cpu(buf, &first_key, 0);
 107                 else
 108                         btrfs_node_key_to_cpu(buf, &first_key, 0);
 109         } else {
 110                 first_key.objectid = 0;
 111         }
 112         cow = __btrfs_alloc_free_block(trans, new_root, buf->len,
 113                                        new_root_objectid,
 114                                        trans->transid, first_key.objectid,
 115                                        level, buf->start, 0);
 116         if (IS_ERR(cow)) {
 117                 kfree(new_root);
 118                 return PTR_ERR(cow);
 119         }
 120
 121         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 122         btrfs_set_header_bytenr(cow, cow->start);
 123         btrfs_set_header_generation(cow, trans->transid);
 124         btrfs_set_header_owner(cow, new_root_objectid);
 125
 126         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 127         ret = btrfs_inc_ref(trans, new_root, buf);
 128         kfree(new_root);
 129
 130         if (ret)
 131                 return ret;
 132
 133         btrfs_mark_buffer_dirty(cow);
 134         *cow_ret = cow;
 135         return 0;
 136 }
 137
 138 int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 139                              struct btrfs_root *root,
 140                              struct extent_buffer *buf,
 141                              struct extent_buffer *parent, int parent_slot,
 142                              struct extent_buffer **cow_ret,
 143                              u64 search_start, u64 empty_size)
 144 {
 145         u64 root_gen;
 146         struct extent_buffer *cow;
 147         u32 nritems;
 148         int ret = 0;
 149         int different_trans = 0;
 150         int level;
 151         struct btrfs_key first_key;
 152
 153         if (root->ref_cows) {
 154                 root_gen = trans->transid;
 155         } else {
 156                 root_gen = 0;
 157         }
 158
 159         WARN_ON(root->ref_cows && trans->transid !=
 160                 root->fs_info->running_transaction->transid);
 161         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 162
 163         level = btrfs_header_level(buf);
 164         nritems = btrfs_header_nritems(buf);
 165         if (nritems) {
 166                 if (level == 0)
 167                         btrfs_item_key_to_cpu(buf, &first_key, 0);
 168                 else
 169                         btrfs_node_key_to_cpu(buf, &first_key, 0);
 170         } else {
 171                 first_key.objectid = 0;
 172         }
 173         cow = __btrfs_alloc_free_block(trans, root, buf->len,
 174                                      root->root_key.objectid,
 175                                      root_gen, first_key.objectid, level,
 176                                      search_start, empty_size);
 177         if (IS_ERR(cow))
 178                 return PTR_ERR(cow);
 179
 180         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 181         btrfs_set_header_bytenr(cow, cow->start);
 182         btrfs_set_header_generation(cow, trans->transid);
 183         btrfs_set_header_owner(cow, root->root_key.objectid);
 184
 185         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 186         if (btrfs_header_generation(buf) != trans->transid) {
 187                 different_trans = 1;
 188                 ret = btrfs_inc_ref(trans, root, buf);
 189                 if (ret)
 190                         return ret;
 191         } else {
 192                 clean_tree_block(trans, root, buf);
 193         }
 194
 195         if (buf == root->node) {
 196                 root_gen = btrfs_header_generation(buf);
 197                 root->node = cow;
 198                 extent_buffer_get(cow);
 199                 if (buf != root->commit_root) {
 200                         btrfs_free_extent(trans, root, buf->start,
 201                                           buf->len, root->root_key.objectid,
 202                                           root_gen, 0, 0, 1);
 203                 }
 204                 free_extent_buffer(buf);
 205                 add_root_to_dirty_list(root);
 206         } else {
 207                 root_gen = btrfs_header_generation(parent);
 208                 btrfs_set_node_blockptr(parent, parent_slot,
 209                                         cow->start);
 210                 WARN_ON(trans->transid == 0);
 211                 btrfs_set_node_ptr_generation(parent, parent_slot,
 212                                               trans->transid);
 213                 btrfs_mark_buffer_dirty(parent);
 214                 WARN_ON(btrfs_header_generation(parent) != trans->transid);
 215                 btrfs_free_extent(trans, root, buf->start, buf->len,
 216                                   btrfs_header_owner(parent), root_gen,
 217                                   0, 0, 1);
 218         }
 219         free_extent_buffer(buf);
 220         btrfs_mark_buffer_dirty(cow);
 221         *cow_ret = cow;
 222         return 0;
 223 }
 224
 225 int btrfs_cow_block(struct btrfs_trans_handle *trans,
 226                     struct btrfs_root *root, struct extent_buffer *buf,
 227                     struct extent_buffer *parent, int parent_slot,
 228                     struct extent_buffer **cow_ret)
 229 {
 230         u64 search_start;
 231         int ret;
 232         /*
 233         if (trans->transaction != root->fs_info->running_transaction) {
 234                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 235                        root->fs_info->running_transaction->transid);
 236                 WARN_ON(1);
 237         }
 238         */
 239         if (trans->transid != root->fs_info->generation) {
 240                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 241                        root->fs_info->generation);
 242                 WARN_ON(1);
 243         }
 244         if (btrfs_header_generation(buf) == trans->transid) {
 245                 *cow_ret = buf;
 246                 return 0;
 247         }
 248
 249         search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
 250         ret = __btrfs_cow_block(trans, root, buf, parent,
 251                                  parent_slot, cow_ret, search_start, 0);
 252         return ret;
 253 }
 254
 255 /*
 256 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 257 {
 258         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 259                 return 1;
 260         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 261                 return 1;
 262         return 0;
 263 }
 264 */
 265
 266 /*
 267  * compare two keys in a memcmp fashion
 268  */
 269 int btrfs_comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 270 {
 271         struct btrfs_key k1;
 272
 273         btrfs_disk_key_to_cpu(&k1, disk);
 274
 275         if (k1.objectid > k2->objectid)
 276                 return 1;
 277         if (k1.objectid < k2->objectid)
 278                 return -1;
 279         if (k1.type > k2->type)
 280                 return 1;
 281         if (k1.type < k2->type)
 282                 return -1;
 283         if (k1.offset > k2->offset)
 284                 return 1;
 285         if (k1.offset < k2->offset)
 286                 return -1;
 287         return 0;
 288 }
 289
 290
 291 #if 0
 292 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 293                        struct btrfs_root *root, struct extent_buffer *parent,
 294                        int start_slot, int cache_only, u64 *last_ret,
 295                        struct btrfs_key *progress)
 296 {
 297         struct extent_buffer *cur;
 298         struct extent_buffer *tmp;
 299         u64 blocknr;
 300         u64 search_start = *last_ret;
 301         u64 last_block = 0;
 302         u64 other;
 303         u32 parent_nritems;
 304         int end_slot;
 305         int i;
 306         int err = 0;
 307         int parent_level;
 308         int uptodate;
 309         u32 blocksize;
 310         int progress_passed = 0;
 311         struct btrfs_disk_key disk_key;
 312
 313         parent_level = btrfs_header_level(parent);
 314         if (cache_only && parent_level != 1)
 315                 return 0;
 316
 317         if (trans->transaction != root->fs_info->running_transaction) {
 318                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 319                        root->fs_info->running_transaction->transid);
 320                 WARN_ON(1);
 321         }
 322         if (trans->transid != root->fs_info->generation) {
 323                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 324                        root->fs_info->generation);
 325                 WARN_ON(1);
 326         }
 327
 328         parent_nritems = btrfs_header_nritems(parent);
 329         blocksize = btrfs_level_size(root, parent_level - 1);
 330         end_slot = parent_nritems;
 331
 332         if (parent_nritems == 1)
 333                 return 0;
 334
 335         for (i = start_slot; i < end_slot; i++) {
 336                 int close = 1;
 337
 338                 if (!parent->map_token) {
 339                         map_extent_buffer(parent,
 340                                         btrfs_node_key_ptr_offset(i),
 341                                         sizeof(struct btrfs_key_ptr),
 342                                         &parent->map_token, &parent->kaddr,
 343                                         &parent->map_start, &parent->map_len,
 344                                         KM_USER1);
 345                 }
 346                 btrfs_node_key(parent, &disk_key, i);
 347                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
 348                         continue;
 349
 350                 progress_passed = 1;
 351                 blocknr = btrfs_node_blockptr(parent, i);
 352                 if (last_block == 0)
 353                         last_block = blocknr;
 354
 355                 if (i > 0) {
 356                         other = btrfs_node_blockptr(parent, i - 1);
 357                         close = close_blocks(blocknr, other, blocksize);
 358                 }
 359                 if (close && i < end_slot - 2) {
 360                         other = btrfs_node_blockptr(parent, i + 1);
 361                         close = close_blocks(blocknr, other, blocksize);
 362                 }
 363                 if (close) {
 364                         last_block = blocknr;
 365                         continue;
 366                 }
 367                 if (parent->map_token) {
 368                         unmap_extent_buffer(parent, parent->map_token,
 369                                             KM_USER1);
 370                         parent->map_token = NULL;
 371                 }
 372
 373                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
 374                 if (cur)
 375                         uptodate = btrfs_buffer_uptodate(cur);
 376                 else
 377                         uptodate = 0;
 378                 if (!cur || !uptodate) {
 379                         if (cache_only) {
 380                                 free_extent_buffer(cur);
 381                                 continue;
 382                         }
 383                         if (!cur) {
 384                                 cur = read_tree_block(root, blocknr,
 385                                                          blocksize);
 386                         } else if (!uptodate) {
 387                                 btrfs_read_buffer(cur);
 388                         }
 389                 }
 390                 if (search_start == 0)
 391                         search_start = last_block;
 392
 393                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 394                                         &tmp, search_start,
 395                                         min(16 * blocksize,
 396                                             (end_slot - i) * blocksize));
 397                 if (err) {
 398                         free_extent_buffer(cur);
 399                         break;
 400                 }
 401                 search_start = tmp->start;
 402                 last_block = tmp->start;
 403                 *last_ret = search_start;
 404                 if (parent_level == 1)
 405                         btrfs_clear_buffer_defrag(tmp);
 406                 free_extent_buffer(tmp);
 407         }
 408         if (parent->map_token) {
 409                 unmap_extent_buffer(parent, parent->map_token,
 410                                     KM_USER1);
 411                 parent->map_token = NULL;
 412         }
 413         return err;
 414 }
 415 #endif
 416
 417 /*
 418  * The leaf data grows from end-to-front in the node.
 419  * this returns the address of the start of the last item,
 420  * which is the stop of the leaf data stack
 421  */
 422 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 423                                          struct extent_buffer *leaf)
 424 {
 425         u32 nr = btrfs_header_nritems(leaf);
 426         if (nr == 0)
 427                 return BTRFS_LEAF_DATA_SIZE(root);
 428         return btrfs_item_offset_nr(leaf, nr - 1);
 429 }
 430
 431 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 432                       int level)
 433 {
 434         struct extent_buffer *parent = NULL;
 435         struct extent_buffer *node = path->nodes[level];
 436         struct btrfs_disk_key parent_key;
 437         struct btrfs_disk_key node_key;
 438         int parent_slot;
 439         int slot;
 440         struct btrfs_key cpukey;
 441         u32 nritems = btrfs_header_nritems(node);
 442
 443         if (path->nodes[level + 1])
 444                 parent = path->nodes[level + 1];
 445
 446         slot = path->slots[level];
 447         BUG_ON(nritems == 0);
 448         if (parent) {
 449                 parent_slot = path->slots[level + 1];
 450                 btrfs_node_key(parent, &parent_key, parent_slot);
 451                 btrfs_node_key(node, &node_key, 0);
 452                 BUG_ON(memcmp(&parent_key, &node_key,
 453                               sizeof(struct btrfs_disk_key)));
 454                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 455                        btrfs_header_bytenr(node));
 456         }
 457         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 458         if (slot != 0) {
 459                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 460                 btrfs_node_key(node, &node_key, slot);
 461                 BUG_ON(btrfs_comp_keys(&node_key, &cpukey) <= 0);
 462         }
 463         if (slot < nritems - 1) {
 464                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 465                 btrfs_node_key(node, &node_key, slot);
 466                 BUG_ON(btrfs_comp_keys(&node_key, &cpukey) >= 0);
 467         }
 468         return 0;
 469 }
 470
 471 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 472                       int level)
 473 {
 474         struct extent_buffer *leaf = path->nodes[level];
 475         struct extent_buffer *parent = NULL;
 476         int parent_slot;
 477         struct btrfs_key cpukey;
 478         struct btrfs_disk_key parent_key;
 479         struct btrfs_disk_key leaf_key;
 480         int slot = path->slots[0];
 481
 482         u32 nritems = btrfs_header_nritems(leaf);
 483
 484         if (path->nodes[level + 1])
 485                 parent = path->nodes[level + 1];
 486
 487         if (nritems == 0)
 488                 return 0;
 489
 490         if (parent) {
 491                 parent_slot = path->slots[level + 1];
 492                 btrfs_node_key(parent, &parent_key, parent_slot);
 493                 btrfs_item_key(leaf, &leaf_key, 0);
 494
 495                 BUG_ON(memcmp(&parent_key, &leaf_key,
 496                        sizeof(struct btrfs_disk_key)));
 497                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 498                        btrfs_header_bytenr(leaf));
 499         }
 500 #if 0
 501         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 502                 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
 503                 btrfs_item_key(leaf, &leaf_key, i);
 504                 if (comp_keys(&leaf_key, &cpukey) >= 0) {
 505                         btrfs_print_leaf(root, leaf);
 506                         printk("slot %d offset bad key\n", i);
 507                         BUG_ON(1);
 508                 }
 509                 if (btrfs_item_offset_nr(leaf, i) !=
 510                         btrfs_item_end_nr(leaf, i + 1)) {
 511                         btrfs_print_leaf(root, leaf);
 512                         printk("slot %d offset bad\n", i);
 513                         BUG_ON(1);
 514                 }
 515                 if (i == 0) {
 516                         if (btrfs_item_offset_nr(leaf, i) +
 517                                btrfs_item_size_nr(leaf, i) !=
 518                                BTRFS_LEAF_DATA_SIZE(root)) {
 519                                 btrfs_print_leaf(root, leaf);
 520                                 printk("slot %d first offset bad\n", i);
 521                                 BUG_ON(1);
 522                         }
 523                 }
 524         }
 525         if (nritems > 0) {
 526                 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
 527                                 btrfs_print_leaf(root, leaf);
 528                                 printk("slot %d bad size \n", nritems - 1);
 529                                 BUG_ON(1);
 530                 }
 531         }
 532 #endif
 533         if (slot != 0 && slot < nritems - 1) {
 534                 btrfs_item_key(leaf, &leaf_key, slot);
 535                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 536                 if (btrfs_comp_keys(&leaf_key, &cpukey) <= 0) {
 537                         btrfs_print_leaf(root, leaf);
 538                         printk("slot %d offset bad key\n", slot);
 539                         BUG_ON(1);
 540                 }
 541                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 542                        btrfs_item_end_nr(leaf, slot)) {
 543                         btrfs_print_leaf(root, leaf);
 544                         printk("slot %d offset bad\n", slot);
 545                         BUG_ON(1);
 546                 }
 547         }
 548         if (slot < nritems - 1) {
 549                 btrfs_item_key(leaf, &leaf_key, slot);
 550                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 551                 BUG_ON(btrfs_comp_keys(&leaf_key, &cpukey) >= 0);
 552                 if (btrfs_item_offset_nr(leaf, slot) !=
 553                         btrfs_item_end_nr(leaf, slot + 1)) {
 554                         btrfs_print_leaf(root, leaf);
 555                         printk("slot %d offset bad\n", slot);
 556                         BUG_ON(1);
 557                 }
 558         }
 559         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 560                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 561         return 0;
 562 }
 563
 564 static int noinline check_block(struct btrfs_root *root,
 565                                 struct btrfs_path *path, int level)
 566 {
 567         return 0;
 568 #if 0
 569         struct extent_buffer *buf = path->nodes[level];
 570
 571         if (memcmp_extent_buffer(buf, root->fs_info->fsid,
 572                                  (unsigned long)btrfs_header_fsid(buf),
 573                                  BTRFS_FSID_SIZE)) {
 574                 printk("warning bad block %Lu\n", buf->start);
 575                 return 1;
 576         }
 577 #endif
 578         if (level == 0)
 579                 return check_leaf(root, path, level);
 580         return check_node(root, path, level);
 581 }
 582
 583 /*
 584  * search for key in the extent_buffer.  The items start at offset p,
 585  * and they are item_size apart.  There are 'max' items in p.
 586  *
 587  * the slot in the array is returned via slot, and it points to
 588  * the place where you would insert key if it is not found in
 589  * the array.
 590  *
 591  * slot may point to max if the key is bigger than all of the keys
 592  */
 593 static int generic_bin_search(struct extent_buffer *eb, unsigned long p,
 594                               int item_size, struct btrfs_key *key,
 595                               int max, int *slot)
 596 {
 597         int low = 0;
 598         int high = max;
 599         int mid;
 600         int ret;
 601         unsigned long offset;
 602         struct btrfs_disk_key *tmp;
 603
 604         while(low < high) {
 605                 mid = (low + high) / 2;
 606                 offset = p + mid * item_size;
 607
 608                 tmp = (struct btrfs_disk_key *)(eb->data + offset);
 609                 ret = btrfs_comp_keys(tmp, key);
 610
 611                 if (ret < 0)
 612                         low = mid + 1;
 613                 else if (ret > 0)
 614                         high = mid;
 615                 else {
 616                         *slot = mid;
 617                         return 0;
 618                 }
 619         }
 620         *slot = low;
 621         return 1;
 622 }
 623
 624 /*
 625  * simple bin_search frontend that does the right thing for
 626  * leaves vs nodes
 627  */
 628 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 629                       int level, int *slot)
 630 {
 631         if (level == 0) {
 632                 return generic_bin_search(eb,
 633                                           offsetof(struct btrfs_leaf, items),
 634                                           sizeof(struct btrfs_item),
 635                                           key, btrfs_header_nritems(eb),
 636                                           slot);
 637         } else {
 638                 return generic_bin_search(eb,
 639                                           offsetof(struct btrfs_node, ptrs),
 640                                           sizeof(struct btrfs_key_ptr),
 641                                           key, btrfs_header_nritems(eb),
 642                                           slot);
 643         }
 644         return -1;
 645 }
 646
 647 static struct extent_buffer *read_node_slot(struct btrfs_root *root,
 648                                    struct extent_buffer *parent, int slot)
 649 {
 650         if (slot < 0)
 651                 return NULL;
 652         if (slot >= btrfs_header_nritems(parent))
 653                 return NULL;
 654         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 655                        btrfs_level_size(root, btrfs_header_level(parent) - 1));
 656 }
 657
 658 static int balance_level(struct btrfs_trans_handle *trans,
 659                          struct btrfs_root *root,
 660                          struct btrfs_path *path, int level)
 661 {
 662         struct extent_buffer *right = NULL;
 663         struct extent_buffer *mid;
 664         struct extent_buffer *left = NULL;
 665         struct extent_buffer *parent = NULL;
 666         int ret = 0;
 667         int wret;
 668         int pslot;
 669         int orig_slot = path->slots[level];
 670         int err_on_enospc = 0;
 671         u64 orig_ptr;
 672
 673         if (level == 0)
 674                 return 0;
 675
 676         mid = path->nodes[level];
 677         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 678
 679         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 680
 681         if (level < BTRFS_MAX_LEVEL - 1)
 682                 parent = path->nodes[level + 1];
 683         pslot = path->slots[level + 1];
 684
 685         /*
 686          * deal with the case where there is only one pointer in the root
 687          * by promoting the node below to a root
 688          */
 689         if (!parent) {
 690                 struct extent_buffer *child;
 691
 692                 if (btrfs_header_nritems(mid) != 1)
 693                         return 0;
 694
 695                 /* promote the child to a root */
 696                 child = read_node_slot(root, mid, 0);
 697                 BUG_ON(!child);
 698                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
 699                 BUG_ON(ret);
 700
 701                 root->node = child;
 702                 add_root_to_dirty_list(root);
 703                 path->nodes[level] = NULL;
 704                 clean_tree_block(trans, root, mid);
 705                 wait_on_tree_block_writeback(root, mid);
 706                 /* once for the path */
 707                 free_extent_buffer(mid);
 708                 ret = btrfs_free_extent(trans, root, mid->start, mid->len,
 709                                         root->root_key.objectid,
 710                                         btrfs_header_generation(mid), 0, 0, 1);
 711                 /* once for the root ptr */
 712                 free_extent_buffer(mid);
 713                 return ret;
 714         }
 715         if (btrfs_header_nritems(mid) >
 716             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 717                 return 0;
 718
 719         if (btrfs_header_nritems(mid) < 2)
 720                 err_on_enospc = 1;
 721
 722         left = read_node_slot(root, parent, pslot - 1);
 723         if (left) {
 724                 wret = btrfs_cow_block(trans, root, left,
 725                                        parent, pslot - 1, &left);
 726                 if (wret) {
 727                         ret = wret;
 728                         goto enospc;
 729                 }
 730         }
 731         right = read_node_slot(root, parent, pslot + 1);
 732         if (right) {
 733                 wret = btrfs_cow_block(trans, root, right,
 734                                        parent, pslot + 1, &right);
 735                 if (wret) {
 736                         ret = wret;
 737                         goto enospc;
 738                 }
 739         }
 740
 741         /* first, try to make some room in the middle buffer */
 742         if (left) {
 743                 orig_slot += btrfs_header_nritems(left);
 744                 wret = push_node_left(trans, root, left, mid);
 745                 if (wret < 0)
 746                         ret = wret;
 747                 if (btrfs_header_nritems(mid) < 2)
 748                         err_on_enospc = 1;
 749         }
 750
 751         /*
 752          * then try to empty the right most buffer into the middle
 753          */
 754         if (right) {
 755                 wret = push_node_left(trans, root, mid, right);
 756                 if (wret < 0 && wret != -ENOSPC)
 757                         ret = wret;
 758                 if (btrfs_header_nritems(right) == 0) {
 759                         u64 bytenr = right->start;
 760                         u64 generation = btrfs_header_generation(parent);
 761                         u32 blocksize = right->len;
 762
 763                         clean_tree_block(trans, root, right);
 764                         wait_on_tree_block_writeback(root, right);
 765                         free_extent_buffer(right);
 766                         right = NULL;
 767                         wret = del_ptr(trans, root, path, level + 1, pslot +
 768                                        1);
 769                         if (wret)
 770                                 ret = wret;
 771                         wret = btrfs_free_extent(trans, root, bytenr,
 772                                                  blocksize,
 773                                                  btrfs_header_owner(parent),
 774                                                  generation, 0, 0, 1);
 775                         if (wret)
 776                                 ret = wret;
 777                 } else {
 778                         struct btrfs_disk_key right_key;
 779                         btrfs_node_key(right, &right_key, 0);
 780                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 781                         btrfs_mark_buffer_dirty(parent);
 782                 }
 783         }
 784         if (btrfs_header_nritems(mid) == 1) {
 785                 /*
 786                  * we're not allowed to leave a node with one item in the
 787                  * tree during a delete.  A deletion from lower in the tree
 788                  * could try to delete the only pointer in this node.
 789                  * So, pull some keys from the left.
 790                  * There has to be a left pointer at this point because
 791                  * otherwise we would have pulled some pointers from the
 792                  * right
 793                  */
 794                 BUG_ON(!left);
 795                 wret = balance_node_right(trans, root, mid, left);
 796                 if (wret < 0) {
 797                         ret = wret;
 798                         goto enospc;
 799                 }
 800                 BUG_ON(wret == 1);
 801         }
 802         if (btrfs_header_nritems(mid) == 0) {
 803                 /* we've managed to empty the middle node, drop it */
 804                 u64 root_gen = btrfs_header_generation(parent);
 805                 u64 bytenr = mid->start;
 806                 u32 blocksize = mid->len;
 807                 clean_tree_block(trans, root, mid);
 808                 wait_on_tree_block_writeback(root, mid);
 809                 free_extent_buffer(mid);
 810                 mid = NULL;
 811                 wret = del_ptr(trans, root, path, level + 1, pslot);
 812                 if (wret)
 813                         ret = wret;
 814                 wret = btrfs_free_extent(trans, root, bytenr, blocksize,
 815                                          btrfs_header_owner(parent),
 816                                          root_gen, 0, 0, 1);
 817                 if (wret)
 818                         ret = wret;
 819         } else {
 820                 /* update the parent key to reflect our changes */
 821                 struct btrfs_disk_key mid_key;
 822                 btrfs_node_key(mid, &mid_key, 0);
 823                 btrfs_set_node_key(parent, &mid_key, pslot);
 824                 btrfs_mark_buffer_dirty(parent);
 825         }
 826
 827         /* update the path */
 828         if (left) {
 829                 if (btrfs_header_nritems(left) > orig_slot) {
 830                         extent_buffer_get(left);
 831                         path->nodes[level] = left;
 832                         path->slots[level + 1] -= 1;
 833                         path->slots[level] = orig_slot;
 834                         if (mid)
 835                                 free_extent_buffer(mid);
 836                 } else {
 837                         orig_slot -= btrfs_header_nritems(left);
 838                         path->slots[level] = orig_slot;
 839                 }
 840         }
 841         /* double check we haven't messed things up */
 842         check_block(root, path, level);
 843         if (orig_ptr !=
 844             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 845                 BUG();
 846 enospc:
 847         if (right)
 848                 free_extent_buffer(right);
 849         if (left)
 850                 free_extent_buffer(left);
 851         return ret;
 852 }
 853
 854 /* returns zero if the push worked, non-zero otherwise */
 855 static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
 856                                           struct btrfs_root *root,
 857                                           struct btrfs_path *path, int level)
 858 {
 859         struct extent_buffer *right = NULL;
 860         struct extent_buffer *mid;
 861         struct extent_buffer *left = NULL;
 862         struct extent_buffer *parent = NULL;
 863         int ret = 0;
 864         int wret;
 865         int pslot;
 866         int orig_slot = path->slots[level];
 867         u64 orig_ptr;
 868
 869         if (level == 0)
 870                 return 1;
 871
 872         mid = path->nodes[level];
 873         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 874         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 875
 876         if (level < BTRFS_MAX_LEVEL - 1)
 877                 parent = path->nodes[level + 1];
 878         pslot = path->slots[level + 1];
 879
 880         if (!parent)
 881                 return 1;
 882
 883         left = read_node_slot(root, parent, pslot - 1);
 884
 885         /* first, try to make some room in the middle buffer */
 886         if (left) {
 887                 u32 left_nr;
 888                 left_nr = btrfs_header_nritems(left);
 889                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 890                         wret = 1;
 891                 } else {
 892                         ret = btrfs_cow_block(trans, root, left, parent,
 893                                               pslot - 1, &left);
 894                         if (ret)
 895                                 wret = 1;
 896                         else {
 897                                 wret = push_node_left(trans, root,
 898                                                       left, mid);
 899                         }
 900                 }
 901                 if (wret < 0)
 902                         ret = wret;
 903                 if (wret == 0) {
 904                         struct btrfs_disk_key disk_key;
 905                         orig_slot += left_nr;
 906                         btrfs_node_key(mid, &disk_key, 0);
 907                         btrfs_set_node_key(parent, &disk_key, pslot);
 908                         btrfs_mark_buffer_dirty(parent);
 909                         if (btrfs_header_nritems(left) > orig_slot) {
 910                                 path->nodes[level] = left;
 911                                 path->slots[level + 1] -= 1;
 912                                 path->slots[level] = orig_slot;
 913                                 free_extent_buffer(mid);
 914                         } else {
 915                                 orig_slot -=
 916                                         btrfs_header_nritems(left);
 917                                 path->slots[level] = orig_slot;
 918                                 free_extent_buffer(left);
 919                         }
 920                         return 0;
 921                 }
 922                 free_extent_buffer(left);
 923         }
 924         right= read_node_slot(root, parent, pslot + 1);
 925
 926         /*
 927          * then try to empty the right most buffer into the middle
 928          */
 929         if (right) {
 930                 u32 right_nr;
 931                 right_nr = btrfs_header_nritems(right);
 932                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 933                         wret = 1;
 934                 } else {
 935                         ret = btrfs_cow_block(trans, root, right,
 936                                               parent, pslot + 1,
 937                                               &right);
 938                         if (ret)
 939                                 wret = 1;
 940                         else {
 941                                 wret = balance_node_right(trans, root,
 942                                                           right, mid);
 943                         }
 944                 }
 945                 if (wret < 0)
 946                         ret = wret;
 947                 if (wret == 0) {
 948                         struct btrfs_disk_key disk_key;
 949
 950                         btrfs_node_key(right, &disk_key, 0);
 951                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
 952                         btrfs_mark_buffer_dirty(parent);
 953
 954                         if (btrfs_header_nritems(mid) <= orig_slot) {
 955                                 path->nodes[level] = right;
 956                                 path->slots[level + 1] += 1;
 957                                 path->slots[level] = orig_slot -
 958                                         btrfs_header_nritems(mid);
 959                                 free_extent_buffer(mid);
 960                         } else {
 961                                 free_extent_buffer(right);
 962                         }
 963                         return 0;
 964                 }
 965                 free_extent_buffer(right);
 966         }
 967         return 1;
 968 }
 969
 970 /*
 971  * readahead one full node of leaves
 972  */
 973 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 974                              int level, int slot, u64 objectid)
 975 {
 976         struct extent_buffer *node;
 977         struct btrfs_disk_key disk_key;
 978         u32 nritems;
 979         u64 search;
 980         u64 lowest_read;
 981         u64 highest_read;
 982         u64 nread = 0;
 983         int direction = path->reada;
 984         struct extent_buffer *eb;
 985         u32 nr;
 986         u32 blocksize;
 987         u32 nscan = 0;
 988
 989         if (level != 1)
 990                 return;
 991
 992         if (!path->nodes[level])
 993                 return;
 994
 995         node = path->nodes[level];
 996         search = btrfs_node_blockptr(node, slot);
 997         blocksize = btrfs_level_size(root, level - 1);
 998         eb = btrfs_find_tree_block(root, search, blocksize);
 999         if (eb) {
1000                 free_extent_buffer(eb);
1001                 return;
1002         }
1003
1004         highest_read = search;
1005         lowest_read = search;
1006
1007         nritems = btrfs_header_nritems(node);
1008         nr = slot;
1009         while(1) {
1010                 if (direction < 0) {
1011                         if (nr == 0)
1012                                 break;
1013                         nr--;
1014                 } else if (direction > 0) {
1015                         nr++;
1016                         if (nr >= nritems)
1017                                 break;
1018                 }
1019                 if (path->reada < 0 && objectid) {
1020                         btrfs_node_key(node, &disk_key, nr);
1021                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1022                                 break;
1023                 }
1024                 search = btrfs_node_blockptr(node, nr);
1025                 if ((search >= lowest_read && search <= highest_read) ||
1026                     (search < lowest_read && lowest_read - search <= 32768) ||
1027                     (search > highest_read && search - highest_read <= 32768)) {
1028                         readahead_tree_block(root, search, blocksize);
1029                         nread += blocksize;
1030                 }
1031                 nscan++;
1032                 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
1033                         break;
1034                 if(nread > (1024 * 1024) || nscan > 128)
1035                         break;
1036
1037                 if (search < lowest_read)
1038                         lowest_read = search;
1039                 if (search > highest_read)
1040                         highest_read = search;
1041         }
1042 }
1043
1044 /*
1045  * look for key in the tree.  path is filled in with nodes along the way
1046  * if key is found, we return zero and you can find the item in the leaf
1047  * level of the path (level 0)
1048  *
1049  * If the key isn't found, the path points to the slot where it should
1050  * be inserted, and 1 is returned.  If there are other errors during the
1051  * search a negative error number is returned.
1052  *
1053  * if ins_len > 0, nodes and leaves will be split as we walk down the
1054  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
1055  * possible)
1056  */
1057 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1058                       *root, struct btrfs_key *key, struct btrfs_path *p, int
1059                       ins_len, int cow)
1060 {
1061         struct extent_buffer *b;
1062         u64 bytenr;
1063         u64 ptr_gen;
1064         int slot;
1065         int ret;
1066         int level;
1067         int should_reada = p->reada;
1068         u8 lowest_level = 0;
1069
1070         lowest_level = p->lowest_level;
1071         WARN_ON(lowest_level && ins_len);
1072         WARN_ON(p->nodes[0] != NULL);
1073         /*
1074         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
1075         */
1076 again:
1077         b = root->node;
1078         extent_buffer_get(b);
1079         while (b) {
1080                 level = btrfs_header_level(b);
1081                 if (cow) {
1082                         int wret;
1083                         wret = btrfs_cow_block(trans, root, b,
1084                                                p->nodes[level + 1],
1085                                                p->slots[level + 1],
1086                                                &b);
1087                         if (wret) {
1088                                 free_extent_buffer(b);
1089                                 return wret;
1090                         }
1091                 }
1092                 BUG_ON(!cow && ins_len);
1093                 if (level != btrfs_header_level(b))
1094                         WARN_ON(1);
1095                 level = btrfs_header_level(b);
1096                 p->nodes[level] = b;
1097                 ret = check_block(root, p, level);
1098                 if (ret)
1099                         return -1;
1100                 ret = bin_search(b, key, level, &slot);
1101                 if (level != 0) {
1102                         if (ret && slot > 0)
1103                                 slot -= 1;
1104                         p->slots[level] = slot;
1105                         if (ins_len > 0 && btrfs_header_nritems(b) >=
1106                             BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1107                                 int sret = split_node(trans, root, p, level);
1108                                 BUG_ON(sret > 0);
1109                                 if (sret)
1110                                         return sret;
1111                                 b = p->nodes[level];
1112                                 slot = p->slots[level];
1113                         } else if (ins_len < 0) {
1114                                 int sret = balance_level(trans, root, p,
1115                                                          level);
1116                                 if (sret)
1117                                         return sret;
1118                                 b = p->nodes[level];
1119                                 if (!b) {
1120                                         btrfs_release_path(NULL, p);
1121                                         goto again;
1122                                 }
1123                                 slot = p->slots[level];
1124                                 BUG_ON(btrfs_header_nritems(b) == 1);
1125                         }
1126                         /* this is only true while dropping a snapshot */
1127                         if (level == lowest_level)
1128                                 break;
1129                         bytenr = btrfs_node_blockptr(b, slot);
1130                         ptr_gen = btrfs_node_ptr_generation(b, slot);
1131                         if (should_reada)
1132                                 reada_for_search(root, p, level, slot,
1133                                                  key->objectid);
1134                         b = read_tree_block(root, bytenr,
1135                                             btrfs_level_size(root, level - 1));
1136                         if (ptr_gen != btrfs_header_generation(b)) {
1137                                 printk("block %llu bad gen wanted %llu "
1138                                        "found %llu\n",
1139                                 (unsigned long long)b->start,
1140                                 (unsigned long long)ptr_gen,
1141                                 (unsigned long long)btrfs_header_generation(b));
1142                         }
1143                 } else {
1144                         p->slots[level] = slot;
1145                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1146                             sizeof(struct btrfs_item) + ins_len) {
1147                                 int sret = split_leaf(trans, root, key,
1148                                                       p, ins_len, ret == 0);
1149                                 BUG_ON(sret > 0);
1150                                 if (sret)
1151                                         return sret;
1152                         }
1153                         return ret;
1154                 }
1155         }
1156         return 1;
1157 }
1158
1159 /*
1160  * adjust the pointers going up the tree, starting at level
1161  * making sure the right key of each node is points to 'key'.
1162  * This is used after shifting pointers to the left, so it stops
1163  * fixing up pointers when a given leaf/node is not in slot 0 of the
1164  * higher levels
1165  *
1166  * If this fails to write a tree block, it returns -1, but continues
1167  * fixing up the blocks in ram so the tree is consistent.
1168  */
1169 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1170                           struct btrfs_root *root, struct btrfs_path *path,
1171                           struct btrfs_disk_key *key, int level)
1172 {
1173         int i;
1174         int ret = 0;
1175         struct extent_buffer *t;
1176
1177         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1178                 int tslot = path->slots[i];
1179                 if (!path->nodes[i])
1180                         break;
1181                 t = path->nodes[i];
1182                 btrfs_set_node_key(t, key, tslot);
1183                 btrfs_mark_buffer_dirty(path->nodes[i]);
1184                 if (tslot != 0)
1185                         break;
1186         }
1187         return ret;
1188 }
1189
1190 /*
1191  * try to push data from one node into the next node left in the
1192  * tree.
1193  *
1194  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1195  * error, and > 0 if there was no room in the left hand block.
1196  */
1197 static int push_node_left(struct btrfs_trans_handle *trans,
1198                           struct btrfs_root *root, struct extent_buffer *dst,
1199                           struct extent_buffer *src)
1200 {
1201         int push_items = 0;
1202         int src_nritems;
1203         int dst_nritems;
1204         int ret = 0;
1205
1206         src_nritems = btrfs_header_nritems(src);
1207         dst_nritems = btrfs_header_nritems(dst);
1208         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1209         WARN_ON(btrfs_header_generation(src) != trans->transid);
1210         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1211
1212         if (push_items <= 0) {
1213                 return 1;
1214         }
1215
1216         if (src_nritems < push_items)
1217                 push_items = src_nritems;
1218
1219         copy_extent_buffer(dst, src,
1220                            btrfs_node_key_ptr_offset(dst_nritems),
1221                            btrfs_node_key_ptr_offset(0),
1222                            push_items * sizeof(struct btrfs_key_ptr));
1223
1224         if (push_items < src_nritems) {
1225                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1226                                       btrfs_node_key_ptr_offset(push_items),
1227                                       (src_nritems - push_items) *
1228                                       sizeof(struct btrfs_key_ptr));
1229         }
1230         btrfs_set_header_nritems(src, src_nritems - push_items);
1231         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1232         btrfs_mark_buffer_dirty(src);
1233         btrfs_mark_buffer_dirty(dst);
1234         return ret;
1235 }
1236
1237 /*
1238  * try to push data from one node into the next node right in the
1239  * tree.
1240  *
1241  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1242  * error, and > 0 if there was no room in the right hand block.
1243  *
1244  * this will  only push up to 1/2 the contents of the left node over
1245  */
1246 static int balance_node_right(struct btrfs_trans_handle *trans,
1247                               struct btrfs_root *root,
1248                               struct extent_buffer *dst,
1249                               struct extent_buffer *src)
1250 {
1251         int push_items = 0;
1252         int max_push;
1253         int src_nritems;
1254         int dst_nritems;
1255         int ret = 0;
1256
1257         WARN_ON(btrfs_header_generation(src) != trans->transid);
1258         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1259
1260         src_nritems = btrfs_header_nritems(src);
1261         dst_nritems = btrfs_header_nritems(dst);
1262         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1263         if (push_items <= 0)
1264                 return 1;
1265
1266         max_push = src_nritems / 2 + 1;
1267         /* don't try to empty the node */
1268         if (max_push >= src_nritems)
1269                 return 1;
1270
1271         if (max_push < push_items)
1272                 push_items = max_push;
1273
1274         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1275                                       btrfs_node_key_ptr_offset(0),
1276                                       (dst_nritems) *
1277                                       sizeof(struct btrfs_key_ptr));
1278
1279         copy_extent_buffer(dst, src,
1280                            btrfs_node_key_ptr_offset(0),
1281                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1282                            push_items * sizeof(struct btrfs_key_ptr));
1283
1284         btrfs_set_header_nritems(src, src_nritems - push_items);
1285         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1286
1287         btrfs_mark_buffer_dirty(src);
1288         btrfs_mark_buffer_dirty(dst);
1289         return ret;
1290 }
1291
1292 /*
1293  * helper function to insert a new root level in the tree.
1294  * A new node is allocated, and a single item is inserted to
1295  * point to the existing root
1296  *
1297  * returns zero on success or < 0 on failure.
1298  */
1299 static int noinline insert_new_root(struct btrfs_trans_handle *trans,
1300                            struct btrfs_root *root,
1301                            struct btrfs_path *path, int level)
1302 {
1303         u64 root_gen;
1304         u64 lower_gen;
1305         struct extent_buffer *lower;
1306         struct extent_buffer *c;
1307         struct btrfs_disk_key lower_key;
1308
1309         BUG_ON(path->nodes[level]);
1310         BUG_ON(path->nodes[level-1] != root->node);
1311
1312         if (root->ref_cows)
1313                 root_gen = trans->transid;
1314         else
1315                 root_gen = 0;
1316
1317         lower = path->nodes[level-1];
1318         if (level == 1)
1319                 btrfs_item_key(lower, &lower_key, 0);
1320         else
1321                 btrfs_node_key(lower, &lower_key, 0);
1322
1323         c = __btrfs_alloc_free_block(trans, root, root->nodesize,
1324                                    root->root_key.objectid,
1325                                    root_gen, lower_key.objectid, level,
1326                                    root->node->start, 0);
1327         if (IS_ERR(c))
1328                 return PTR_ERR(c);
1329         memset_extent_buffer(c, 0, 0, root->nodesize);
1330         btrfs_set_header_nritems(c, 1);
1331         btrfs_set_header_level(c, level);
1332         btrfs_set_header_bytenr(c, c->start);
1333         btrfs_set_header_generation(c, trans->transid);
1334         btrfs_set_header_owner(c, root->root_key.objectid);
1335
1336         write_extent_buffer(c, root->fs_info->fsid,
1337                             (unsigned long)btrfs_header_fsid(c),
1338                             BTRFS_FSID_SIZE);
1339         btrfs_set_node_key(c, &lower_key, 0);
1340         btrfs_set_node_blockptr(c, 0, lower->start);
1341         lower_gen = btrfs_header_generation(lower);
1342         WARN_ON(lower_gen == 0);
1343
1344         btrfs_set_node_ptr_generation(c, 0, lower_gen);
1345
1346         btrfs_mark_buffer_dirty(c);
1347
1348         /* the super has an extra ref to root->node */
1349         free_extent_buffer(root->node);
1350         root->node = c;
1351         add_root_to_dirty_list(root);
1352         extent_buffer_get(c);
1353         path->nodes[level] = c;
1354         path->slots[level] = 0;
1355
1356         if (root->ref_cows && lower_gen != trans->transid) {
1357                 struct btrfs_path *back_path = btrfs_alloc_path();
1358                 int ret;
1359                 ret = btrfs_insert_extent_backref(trans,
1360                                                   root->fs_info->extent_root,
1361                                                   path, lower->start,
1362                                                   root->root_key.objectid,
1363                                                   trans->transid, 0, 0);
1364                 BUG_ON(ret);
1365                 btrfs_free_path(back_path);
1366         }
1367         return 0;
1368 }
1369
1370 /*
1371  * worker function to insert a single pointer in a node.
1372  * the node should have enough room for the pointer already
1373  *
1374  * slot and level indicate where you want the key to go, and
1375  * blocknr is the block the key points to.
1376  *
1377  * returns zero on success and < 0 on any error
1378  */
1379 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1380                       *root, struct btrfs_path *path, struct btrfs_disk_key
1381                       *key, u64 bytenr, int slot, int level)
1382 {
1383         struct extent_buffer *lower;
1384         int nritems;
1385
1386         BUG_ON(!path->nodes[level]);
1387         lower = path->nodes[level];
1388         nritems = btrfs_header_nritems(lower);
1389         if (slot > nritems)
1390                 BUG();
1391         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1392                 BUG();
1393         if (slot != nritems) {
1394                 memmove_extent_buffer(lower,
1395                               btrfs_node_key_ptr_offset(slot + 1),
1396                               btrfs_node_key_ptr_offset(slot),
1397                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1398         }
1399         btrfs_set_node_key(lower, key, slot);
1400         btrfs_set_node_blockptr(lower, slot, bytenr);
1401         WARN_ON(trans->transid == 0);
1402         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
1403         btrfs_set_header_nritems(lower, nritems + 1);
1404         btrfs_mark_buffer_dirty(lower);
1405         return 0;
1406 }
1407
1408 /*
1409  * split the node at the specified level in path in two.
1410  * The path is corrected to point to the appropriate node after the split
1411  *
1412  * Before splitting this tries to make some room in the node by pushing
1413  * left and right, if either one works, it returns right away.
1414  *
1415  * returns 0 on success and < 0 on failure
1416  */
1417 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1418                       *root, struct btrfs_path *path, int level)
1419 {
1420         u64 root_gen;
1421         struct extent_buffer *c;
1422         struct extent_buffer *split;
1423         struct btrfs_disk_key disk_key;
1424         int mid;
1425         int ret;
1426         int wret;
1427         u32 c_nritems;
1428
1429         c = path->nodes[level];
1430         WARN_ON(btrfs_header_generation(c) != trans->transid);
1431         if (c == root->node) {
1432                 /* trying to split the root, lets make a new one */
1433                 ret = insert_new_root(trans, root, path, level + 1);
1434                 if (ret)
1435                         return ret;
1436         } else {
1437                 ret = push_nodes_for_insert(trans, root, path, level);
1438                 c = path->nodes[level];
1439                 if (!ret && btrfs_header_nritems(c) <
1440                     BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
1441                         return 0;
1442                 if (ret < 0)
1443                         return ret;
1444         }
1445
1446         c_nritems = btrfs_header_nritems(c);
1447         if (root->ref_cows)
1448                 root_gen = trans->transid;
1449         else
1450                 root_gen = 0;
1451
1452         btrfs_node_key(c, &disk_key, 0);
1453         split = __btrfs_alloc_free_block(trans, root, root->nodesize,
1454                                          root->root_key.objectid,
1455                                          root_gen,
1456                                          btrfs_disk_key_objectid(&disk_key),
1457                                          level, c->start, 0);
1458         if (IS_ERR(split))
1459                 return PTR_ERR(split);
1460
1461         btrfs_set_header_flags(split, btrfs_header_flags(c));
1462         btrfs_set_header_level(split, btrfs_header_level(c));
1463         btrfs_set_header_bytenr(split, split->start);
1464         btrfs_set_header_generation(split, trans->transid);
1465         btrfs_set_header_owner(split, root->root_key.objectid);
1466         write_extent_buffer(split, root->fs_info->fsid,
1467                             (unsigned long)btrfs_header_fsid(split),
1468                             BTRFS_FSID_SIZE);
1469
1470         mid = (c_nritems + 1) / 2;
1471
1472         copy_extent_buffer(split, c,
1473                            btrfs_node_key_ptr_offset(0),
1474                            btrfs_node_key_ptr_offset(mid),
1475                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1476         btrfs_set_header_nritems(split, c_nritems - mid);
1477         btrfs_set_header_nritems(c, mid);
1478         ret = 0;
1479
1480         btrfs_mark_buffer_dirty(c);
1481         btrfs_mark_buffer_dirty(split);
1482
1483         btrfs_node_key(split, &disk_key, 0);
1484         wret = insert_ptr(trans, root, path, &disk_key, split->start,
1485                           path->slots[level + 1] + 1,
1486                           level + 1);
1487         if (wret)
1488                 ret = wret;
1489
1490         if (path->slots[level] >= mid) {
1491                 path->slots[level] -= mid;
1492                 free_extent_buffer(c);
1493                 path->nodes[level] = split;
1494                 path->slots[level + 1] += 1;
1495         } else {
1496                 free_extent_buffer(split);
1497         }
1498         return ret;
1499 }
1500
1501 /*
1502  * how many bytes are required to store the items in a leaf.  start
1503  * and nr indicate which items in the leaf to check.  This totals up the
1504  * space used both by the item structs and the item data
1505  */
1506 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1507 {
1508         int data_len;
1509         int nritems = btrfs_header_nritems(l);
1510         int end = min(nritems, start + nr) - 1;
1511
1512         if (!nr)
1513                 return 0;
1514         data_len = btrfs_item_end_nr(l, start);
1515         data_len = data_len - btrfs_item_offset_nr(l, end);
1516         data_len += sizeof(struct btrfs_item) * nr;
1517         WARN_ON(data_len < 0);
1518         return data_len;
1519 }
1520
1521 /*
1522  * The space between the end of the leaf items and
1523  * the start of the leaf data.  IOW, how much room
1524  * the leaf has left for both items and data
1525  */
1526 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1527 {
1528         int nritems = btrfs_header_nritems(leaf);
1529         int ret;
1530         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1531         if (ret < 0) {
1532                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1533                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
1534                        leaf_space_used(leaf, 0, nritems), nritems);
1535         }
1536         return ret;
1537 }
1538
1539 /*
1540  * push some data in the path leaf to the right, trying to free up at
1541  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1542  *
1543  * returns 1 if the push failed because the other node didn't have enough
1544  * room, 0 if everything worked out and < 0 if there were major errors.
1545  */
1546 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1547                            *root, struct btrfs_path *path, int data_size,
1548                            int empty)
1549 {
1550         struct extent_buffer *left = path->nodes[0];
1551         struct extent_buffer *right;
1552         struct extent_buffer *upper;
1553         struct btrfs_disk_key disk_key;
1554         int slot;
1555         u32 i;
1556         int free_space;
1557         int push_space = 0;
1558         int push_items = 0;
1559         struct btrfs_item *item;
1560         u32 left_nritems;
1561         u32 nr;
1562         u32 right_nritems;
1563         u32 data_end;
1564         u32 this_item_size;
1565         int ret;
1566
1567         slot = path->slots[1];
1568         if (!path->nodes[1]) {
1569                 return 1;
1570         }
1571         upper = path->nodes[1];
1572         if (slot >= btrfs_header_nritems(upper) - 1)
1573                 return 1;
1574
1575         right = read_tree_block(root, btrfs_node_blockptr(upper, slot + 1),
1576                                 root->leafsize);
1577         free_space = btrfs_leaf_free_space(root, right);
1578         if (free_space < data_size + sizeof(struct btrfs_item)) {
1579                 free_extent_buffer(right);
1580                 return 1;
1581         }
1582
1583         /* cow and double check */
1584         ret = btrfs_cow_block(trans, root, right, upper,
1585                               slot + 1, &right);
1586         if (ret) {
1587                 free_extent_buffer(right);
1588                 return 1;
1589         }
1590         free_space = btrfs_leaf_free_space(root, right);
1591         if (free_space < data_size + sizeof(struct btrfs_item)) {
1592                 free_extent_buffer(right);
1593                 return 1;
1594         }
1595
1596         left_nritems = btrfs_header_nritems(left);
1597         if (left_nritems == 0) {
1598                 free_extent_buffer(right);
1599                 return 1;
1600         }
1601
1602         if (empty)
1603                 nr = 0;
1604         else
1605                 nr = 1;
1606
1607         i = left_nritems - 1;
1608         while (i >= nr) {
1609                 item = btrfs_item_nr(left, i);
1610
1611                 if (path->slots[0] == i)
1612                         push_space += data_size + sizeof(*item);
1613
1614                 this_item_size = btrfs_item_size(left, item);
1615                 if (this_item_size + sizeof(*item) + push_space > free_space)
1616                         break;
1617                 push_items++;
1618                 push_space += this_item_size + sizeof(*item);
1619                 if (i == 0)
1620                         break;
1621                 i--;
1622         }
1623
1624         if (push_items == 0) {
1625                 free_extent_buffer(right);
1626                 return 1;
1627         }
1628
1629         if (!empty && push_items == left_nritems)
1630                 WARN_ON(1);
1631
1632         /* push left to right */
1633         right_nritems = btrfs_header_nritems(right);
1634
1635         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1636         push_space -= leaf_data_end(root, left);
1637
1638         /* make room in the right data area */
1639         data_end = leaf_data_end(root, right);
1640         memmove_extent_buffer(right,
1641                               btrfs_leaf_data(right) + data_end - push_space,
1642                               btrfs_leaf_data(right) + data_end,
1643                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1644
1645         /* copy from the left data area */
1646         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1647                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1648                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1649                      push_space);
1650
1651         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1652                               btrfs_item_nr_offset(0),
1653                               right_nritems * sizeof(struct btrfs_item));
1654
1655         /* copy the items from left to right */
1656         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1657                    btrfs_item_nr_offset(left_nritems - push_items),
1658                    push_items * sizeof(struct btrfs_item));
1659
1660         /* update the item pointers */
1661         right_nritems += push_items;
1662         btrfs_set_header_nritems(right, right_nritems);
1663         push_space = BTRFS_LEAF_DATA_SIZE(root);
1664         for (i = 0; i < right_nritems; i++) {
1665                 item = btrfs_item_nr(right, i);
1666                 push_space -= btrfs_item_size(right, item);
1667                 btrfs_set_item_offset(right, item, push_space);
1668         }
1669
1670         left_nritems -= push_items;
1671         btrfs_set_header_nritems(left, left_nritems);
1672
1673         if (left_nritems)
1674                 btrfs_mark_buffer_dirty(left);
1675         btrfs_mark_buffer_dirty(right);
1676
1677         btrfs_item_key(right, &disk_key, 0);
1678         btrfs_set_node_key(upper, &disk_key, slot + 1);
1679         btrfs_mark_buffer_dirty(upper);
1680
1681         /* then fixup the leaf pointer in the path */
1682         if (path->slots[0] >= left_nritems) {
1683                 path->slots[0] -= left_nritems;
1684                 free_extent_buffer(path->nodes[0]);
1685                 path->nodes[0] = right;
1686                 path->slots[1] += 1;
1687         } else {
1688                 free_extent_buffer(right);
1689         }
1690         return 0;
1691 }
1692 /*
1693  * push some data in the path leaf to the left, trying to free up at
1694  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1695  */
1696 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1697                           *root, struct btrfs_path *path, int data_size,
1698                           int empty)
1699 {
1700         struct btrfs_disk_key disk_key;
1701         struct extent_buffer *right = path->nodes[0];
1702         struct extent_buffer *left;
1703         int slot;
1704         int i;
1705         int free_space;
1706         int push_space = 0;
1707         int push_items = 0;
1708         struct btrfs_item *item;
1709         u32 old_left_nritems;
1710         u32 right_nritems;
1711         u32 nr;
1712         int ret = 0;
1713         int wret;
1714         u32 this_item_size;
1715         u32 old_left_item_size;
1716
1717         slot = path->slots[1];
1718         if (slot == 0)
1719                 return 1;
1720         if (!path->nodes[1])
1721                 return 1;
1722
1723         right_nritems = btrfs_header_nritems(right);
1724         if (right_nritems == 0) {
1725                 return 1;
1726         }
1727
1728         left = read_tree_block(root, btrfs_node_blockptr(path->nodes[1],
1729                                slot - 1), root->leafsize);
1730         free_space = btrfs_leaf_free_space(root, left);
1731         if (free_space < data_size + sizeof(struct btrfs_item)) {
1732                 free_extent_buffer(left);
1733                 return 1;
1734         }
1735
1736         /* cow and double check */
1737         ret = btrfs_cow_block(trans, root, left,
1738                               path->nodes[1], slot - 1, &left);
1739         if (ret) {
1740                 /* we hit -ENOSPC, but it isn't fatal here */
1741                 free_extent_buffer(left);
1742                 return 1;
1743         }
1744
1745         free_space = btrfs_leaf_free_space(root, left);
1746         if (free_space < data_size + sizeof(struct btrfs_item)) {
1747                 free_extent_buffer(left);
1748                 return 1;
1749         }
1750
1751         if (empty)
1752                 nr = right_nritems;
1753         else
1754                 nr = right_nritems - 1;
1755
1756         for (i = 0; i < nr; i++) {
1757                 item = btrfs_item_nr(right, i);
1758
1759                 if (path->slots[0] == i)
1760                         push_space += data_size + sizeof(*item);
1761
1762                 this_item_size = btrfs_item_size(right, item);
1763                 if (this_item_size + sizeof(*item) + push_space > free_space)
1764                         break;
1765
1766                 push_items++;
1767                 push_space += this_item_size + sizeof(*item);
1768         }
1769
1770         if (push_items == 0) {
1771                 free_extent_buffer(left);
1772                 return 1;
1773         }
1774         if (!empty && push_items == btrfs_header_nritems(right))
1775                 WARN_ON(1);
1776
1777         /* push data from right to left */
1778         copy_extent_buffer(left, right,
1779                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1780                            btrfs_item_nr_offset(0),
1781                            push_items * sizeof(struct btrfs_item));
1782
1783         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1784                      btrfs_item_offset_nr(right, push_items -1);
1785
1786         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1787                      leaf_data_end(root, left) - push_space,
1788                      btrfs_leaf_data(right) +
1789                      btrfs_item_offset_nr(right, push_items - 1),
1790                      push_space);
1791         old_left_nritems = btrfs_header_nritems(left);
1792         BUG_ON(old_left_nritems < 0);
1793
1794         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
1795         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1796                 u32 ioff;
1797
1798                 item = btrfs_item_nr(left, i);
1799                 ioff = btrfs_item_offset(left, item);
1800                 btrfs_set_item_offset(left, item,
1801                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
1802         }
1803         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1804
1805         /* fixup right node */
1806         if (push_items > right_nritems) {
1807                 printk("push items %d nr %u\n", push_items, right_nritems);
1808                 WARN_ON(1);
1809         }
1810
1811         if (push_items < right_nritems) {
1812                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
1813                                                   leaf_data_end(root, right);
1814                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
1815                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
1816                                       btrfs_leaf_data(right) +
1817                                       leaf_data_end(root, right), push_space);
1818
1819                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1820                               btrfs_item_nr_offset(push_items),
1821                              (btrfs_header_nritems(right) - push_items) *
1822                              sizeof(struct btrfs_item));
1823         }
1824         right_nritems -= push_items;
1825         btrfs_set_header_nritems(right, right_nritems);
1826         push_space = BTRFS_LEAF_DATA_SIZE(root);
1827         for (i = 0; i < right_nritems; i++) {
1828                 item = btrfs_item_nr(right, i);
1829                 push_space = push_space - btrfs_item_size(right, item);
1830                 btrfs_set_item_offset(right, item, push_space);
1831         }
1832
1833         btrfs_mark_buffer_dirty(left);
1834         if (right_nritems)
1835                 btrfs_mark_buffer_dirty(right);
1836
1837         btrfs_item_key(right, &disk_key, 0);
1838         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1839         if (wret)
1840                 ret = wret;
1841
1842         /* then fixup the leaf pointer in the path */
1843         if (path->slots[0] < push_items) {
1844                 path->slots[0] += old_left_nritems;
1845                 free_extent_buffer(path->nodes[0]);
1846                 path->nodes[0] = left;
1847                 path->slots[1] -= 1;
1848         } else {
1849                 free_extent_buffer(left);
1850                 path->slots[0] -= push_items;
1851         }
1852         BUG_ON(path->slots[0] < 0);
1853         return ret;
1854 }
1855
1856 /*
1857  * split the path's leaf in two, making sure there is at least data_size
1858  * available for the resulting leaf level of the path.
1859  *
1860  * returns 0 if all went well and < 0 on failure.
1861  */
1862 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1863                       *root, struct btrfs_key *ins_key,
1864                       struct btrfs_path *path, int data_size, int extend)
1865 {
1866         u64 root_gen;
1867         struct extent_buffer *l;
1868         u32 nritems;
1869         int mid;
1870         int slot;
1871         struct extent_buffer *right;
1872         int space_needed = data_size + sizeof(struct btrfs_item);
1873         int data_copy_size;
1874         int rt_data_off;
1875         int i;
1876         int ret = 0;
1877         int wret;
1878         int double_split;
1879         int num_doubles = 0;
1880         struct btrfs_disk_key disk_key;
1881
1882         if (extend)
1883                 space_needed = data_size;
1884
1885         if (root->ref_cows)
1886                 root_gen = trans->transid;
1887         else
1888                 root_gen = 0;
1889
1890         /* first try to make some room by pushing left and right */
1891         if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
1892                 wret = push_leaf_right(trans, root, path, data_size, 0);
1893                 if (wret < 0) {
1894                         return wret;
1895                 }
1896                 if (wret) {
1897                         wret = push_leaf_left(trans, root, path, data_size, 0);
1898                         if (wret < 0)
1899                                 return wret;
1900                 }
1901                 l = path->nodes[0];
1902
1903                 /* did the pushes work? */
1904                 if (btrfs_leaf_free_space(root, l) >= space_needed)
1905                         return 0;
1906         }
1907
1908         if (!path->nodes[1]) {
1909                 ret = insert_new_root(trans, root, path, 1);
1910                 if (ret)
1911                         return ret;
1912         }
1913 again:
1914         double_split = 0;
1915         l = path->nodes[0];
1916         slot = path->slots[0];
1917         nritems = btrfs_header_nritems(l);
1918         mid = (nritems + 1)/ 2;
1919
1920         btrfs_item_key(l, &disk_key, 0);
1921
1922         right = __btrfs_alloc_free_block(trans, root, root->leafsize,
1923                                          root->root_key.objectid,
1924                                          root_gen, disk_key.objectid, 0,
1925                                          l->start, 0);
1926         if (IS_ERR(right))
1927                 return PTR_ERR(right);
1928
1929         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1930         btrfs_set_header_bytenr(right, right->start);
1931         btrfs_set_header_generation(right, trans->transid);
1932         btrfs_set_header_owner(right, root->root_key.objectid);
1933         btrfs_set_header_level(right, 0);
1934         write_extent_buffer(right, root->fs_info->fsid,
1935                             (unsigned long)btrfs_header_fsid(right),
1936                             BTRFS_FSID_SIZE);
1937         if (mid <= slot) {
1938                 if (nritems == 1 ||
1939                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1940                         BTRFS_LEAF_DATA_SIZE(root)) {
1941                         if (slot >= nritems) {
1942                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1943                                 btrfs_set_header_nritems(right, 0);
1944                                 wret = insert_ptr(trans, root, path,
1945                                                   &disk_key, right->start,
1946                                                   path->slots[1] + 1, 1);
1947                                 if (wret)
1948                                         ret = wret;
1949                                 free_extent_buffer(path->nodes[0]);
1950                                 path->nodes[0] = right;
1951                                 path->slots[0] = 0;
1952                                 path->slots[1] += 1;
1953                                 return ret;
1954                         }
1955                         mid = slot;
1956                         if (mid != nritems &&
1957                             leaf_space_used(l, mid, nritems - mid) +
1958                             space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1959                                 double_split = 1;
1960                         }
1961                 }
1962         } else {
1963                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1964                         BTRFS_LEAF_DATA_SIZE(root)) {
1965                         if (!extend && slot == 0) {
1966                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1967                                 btrfs_set_header_nritems(right, 0);
1968                                 wret = insert_ptr(trans, root, path,
1969                                                   &disk_key,
1970                                                   right->start,
1971                                                   path->slots[1], 1);
1972                                 if (wret)
1973                                         ret = wret;
1974                                 free_extent_buffer(path->nodes[0]);
1975                                 path->nodes[0] = right;
1976                                 path->slots[0] = 0;
1977                                 if (path->slots[1] == 0) {
1978                                         wret = fixup_low_keys(trans, root,
1979                                                    path, &disk_key, 1);
1980                                         if (wret)
1981                                                 ret = wret;
1982                                 }
1983                                 return ret;
1984                         } else if (extend && slot == 0) {
1985                                 mid = 1;
1986                         } else {
1987                                 mid = slot;
1988                                 if (mid != nritems &&
1989                                     leaf_space_used(l, mid, nritems - mid) +
1990                                     space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1991                                         double_split = 1;
1992                                 }
1993                         }
1994                 }
1995         }
1996         nritems = nritems - mid;
1997         btrfs_set_header_nritems(right, nritems);
1998         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
1999
2000         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2001                            btrfs_item_nr_offset(mid),
2002                            nritems * sizeof(struct btrfs_item));
2003
2004         copy_extent_buffer(right, l,
2005                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2006                      data_copy_size, btrfs_leaf_data(l) +
2007                      leaf_data_end(root, l), data_copy_size);
2008
2009         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2010                       btrfs_item_end_nr(l, mid);
2011
2012         for (i = 0; i < nritems; i++) {
2013                 struct btrfs_item *item = btrfs_item_nr(right, i);
2014                 u32 ioff = btrfs_item_offset(right, item);
2015                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2016         }
2017
2018         btrfs_set_header_nritems(l, mid);
2019         ret = 0;
2020         btrfs_item_key(right, &disk_key, 0);
2021         wret = insert_ptr(trans, root, path, &disk_key, right->start,
2022                           path->slots[1] + 1, 1);
2023         if (wret)
2024                 ret = wret;
2025
2026         btrfs_mark_buffer_dirty(right);
2027         btrfs_mark_buffer_dirty(l);
2028         BUG_ON(path->slots[0] != slot);
2029
2030         if (mid <= slot) {
2031                 free_extent_buffer(path->nodes[0]);
2032                 path->nodes[0] = right;
2033                 path->slots[0] -= mid;
2034                 path->slots[1] += 1;
2035         } else
2036                 free_extent_buffer(right);
2037
2038         BUG_ON(path->slots[0] < 0);
2039
2040         if (double_split) {
2041                 BUG_ON(num_doubles != 0);
2042                 num_doubles++;
2043                 goto again;
2044         }
2045         return ret;
2046 }
2047
2048 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
2049                         struct btrfs_root *root,
2050                         struct btrfs_path *path,
2051                         u32 new_size, int from_end)
2052 {
2053         int ret = 0;
2054         int slot;
2055         int slot_orig;
2056         struct extent_buffer *leaf;
2057         struct btrfs_item *item;
2058         u32 nritems;
2059         unsigned int data_end;
2060         unsigned int old_data_start;
2061         unsigned int old_size;
2062         unsigned int size_diff;
2063         int i;
2064
2065         slot_orig = path->slots[0];
2066         leaf = path->nodes[0];
2067         slot = path->slots[0];
2068
2069         old_size = btrfs_item_size_nr(leaf, slot);
2070         if (old_size == new_size)
2071                 return 0;
2072
2073         nritems = btrfs_header_nritems(leaf);
2074         data_end = leaf_data_end(root, leaf);
2075
2076         old_data_start = btrfs_item_offset_nr(leaf, slot);
2077
2078         size_diff = old_size - new_size;
2079
2080         BUG_ON(slot < 0);
2081         BUG_ON(slot >= nritems);
2082
2083         /*
2084          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2085          */
2086         /* first correct the data pointers */
2087         for (i = slot; i < nritems; i++) {
2088                 u32 ioff;
2089                 item = btrfs_item_nr(leaf, i);
2090                 ioff = btrfs_item_offset(leaf, item);
2091                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2092         }
2093
2094         /* shift the data */
2095         if (from_end) {
2096                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2097                               data_end + size_diff, btrfs_leaf_data(leaf) +
2098                               data_end, old_data_start + new_size - data_end);
2099         } else {
2100                 struct btrfs_disk_key disk_key;
2101                 u64 offset;
2102
2103                 btrfs_item_key(leaf, &disk_key, slot);
2104
2105                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
2106                         unsigned long ptr;
2107                         struct btrfs_file_extent_item *fi;
2108
2109                         fi = btrfs_item_ptr(leaf, slot,
2110                                             struct btrfs_file_extent_item);
2111                         fi = (struct btrfs_file_extent_item *)(
2112                              (unsigned long)fi - size_diff);
2113
2114                         if (btrfs_file_extent_type(leaf, fi) ==
2115                             BTRFS_FILE_EXTENT_INLINE) {
2116                                 ptr = btrfs_item_ptr_offset(leaf, slot);
2117                                 memmove_extent_buffer(leaf, ptr,
2118                                         (unsigned long)fi,
2119                                         offsetof(struct btrfs_file_extent_item,
2120                                                  disk_bytenr));
2121                         }
2122                 }
2123
2124                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2125                               data_end + size_diff, btrfs_leaf_data(leaf) +
2126                               data_end, old_data_start - data_end);
2127
2128                 offset = btrfs_disk_key_offset(&disk_key);
2129                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
2130                 btrfs_set_item_key(leaf, &disk_key, slot);
2131                 if (slot == 0)
2132                         fixup_low_keys(trans, root, path, &disk_key, 1);
2133         }
2134
2135         item = btrfs_item_nr(leaf, slot);
2136         btrfs_set_item_size(leaf, item, new_size);
2137         btrfs_mark_buffer_dirty(leaf);
2138
2139         ret = 0;
2140         if (btrfs_leaf_free_space(root, leaf) < 0) {
2141                 btrfs_print_leaf(root, leaf);
2142                 BUG();
2143         }
2144         return ret;
2145 }
2146
2147 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2148                       struct btrfs_root *root, struct btrfs_path *path,
2149                       u32 data_size)
2150 {
2151         int ret = 0;
2152         int slot;
2153         int slot_orig;
2154         struct extent_buffer *leaf;
2155         struct btrfs_item *item;
2156         u32 nritems;
2157         unsigned int data_end;
2158         unsigned int old_data;
2159         unsigned int old_size;
2160         int i;
2161
2162         slot_orig = path->slots[0];
2163         leaf = path->nodes[0];
2164
2165         nritems = btrfs_header_nritems(leaf);
2166         data_end = leaf_data_end(root, leaf);
2167
2168         if (btrfs_leaf_free_space(root, leaf) < data_size) {
2169                 btrfs_print_leaf(root, leaf);
2170                 BUG();
2171         }
2172         slot = path->slots[0];
2173         old_data = btrfs_item_end_nr(leaf, slot);
2174
2175         BUG_ON(slot < 0);
2176         if (slot >= nritems) {
2177                 btrfs_print_leaf(root, leaf);
2178                 printk("slot %d too large, nritems %d\n", slot, nritems);
2179                 BUG_ON(1);
2180         }
2181
2182         /*
2183          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2184          */
2185         /* first correct the data pointers */
2186         for (i = slot; i < nritems; i++) {
2187                 u32 ioff;
2188                 item = btrfs_item_nr(leaf, i);
2189                 ioff = btrfs_item_offset(leaf, item);
2190                 btrfs_set_item_offset(leaf, item, ioff - data_size);
2191         }
2192
2193         /* shift the data */
2194         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2195                       data_end - data_size, btrfs_leaf_data(leaf) +
2196                       data_end, old_data - data_end);
2197
2198         data_end = old_data;
2199         old_size = btrfs_item_size_nr(leaf, slot);
2200         item = btrfs_item_nr(leaf, slot);
2201         btrfs_set_item_size(leaf, item, old_size + data_size);
2202         btrfs_mark_buffer_dirty(leaf);
2203
2204         ret = 0;
2205         if (btrfs_leaf_free_space(root, leaf) < 0) {
2206                 btrfs_print_leaf(root, leaf);
2207                 BUG();
2208         }
2209         return ret;
2210 }
2211
2212 /*
2213  * Given a key and some data, insert an item into the tree.
2214  * This does all the path init required, making room in the tree if needed.
2215  */
2216 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
2217                             struct btrfs_root *root,
2218                             struct btrfs_path *path,
2219                             struct btrfs_key *cpu_key, u32 *data_size,
2220                             int nr)
2221 {
2222         struct extent_buffer *leaf;
2223         struct btrfs_item *item;
2224         int ret = 0;
2225         int slot;
2226         int slot_orig;
2227         int i;
2228         u32 nritems;
2229         u32 total_size = 0;
2230         u32 total_data = 0;
2231         unsigned int data_end;
2232         struct btrfs_disk_key disk_key;
2233
2234         for (i = 0; i < nr; i++) {
2235                 total_data += data_size[i];
2236         }
2237
2238         /* create a root if there isn't one */
2239         if (!root->node)
2240                 BUG();
2241
2242         total_size = total_data + (nr - 1) * sizeof(struct btrfs_item);
2243         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
2244         if (ret == 0) {
2245                 return -EEXIST;
2246         }
2247         if (ret < 0)
2248                 goto out;
2249
2250         slot_orig = path->slots[0];
2251         leaf = path->nodes[0];
2252
2253         nritems = btrfs_header_nritems(leaf);
2254         data_end = leaf_data_end(root, leaf);
2255
2256         if (btrfs_leaf_free_space(root, leaf) <
2257             sizeof(struct btrfs_item) + total_size) {
2258                 btrfs_print_leaf(root, leaf);
2259                 printk("not enough freespace need %u have %d\n",
2260                        total_size, btrfs_leaf_free_space(root, leaf));
2261                 BUG();
2262         }
2263
2264         slot = path->slots[0];
2265         BUG_ON(slot < 0);
2266
2267         if (slot != nritems) {
2268                 int i;
2269                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2270
2271                 if (old_data < data_end) {
2272                         btrfs_print_leaf(root, leaf);
2273                         printk("slot %d old_data %d data_end %d\n",
2274                                slot, old_data, data_end);
2275                         BUG_ON(1);
2276                 }
2277                 /*
2278                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2279                  */
2280                 /* first correct the data pointers */
2281                 for (i = slot; i < nritems; i++) {
2282                         u32 ioff;
2283
2284                         item = btrfs_item_nr(leaf, i);
2285                         ioff = btrfs_item_offset(leaf, item);
2286                         btrfs_set_item_offset(leaf, item, ioff - total_data);
2287                 }
2288
2289                 /* shift the items */
2290                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
2291                               btrfs_item_nr_offset(slot),
2292                               (nritems - slot) * sizeof(struct btrfs_item));
2293
2294                 /* shift the data */
2295                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2296                               data_end - total_data, btrfs_leaf_data(leaf) +
2297                               data_end, old_data - data_end);
2298                 data_end = old_data;
2299         }
2300
2301         /* setup the item for the new data */
2302         for (i = 0; i < nr; i++) {
2303                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
2304                 btrfs_set_item_key(leaf, &disk_key, slot + i);
2305                 item = btrfs_item_nr(leaf, slot + i);
2306                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
2307                 data_end -= data_size[i];
2308                 btrfs_set_item_size(leaf, item, data_size[i]);
2309         }
2310         btrfs_set_header_nritems(leaf, nritems + nr);
2311         btrfs_mark_buffer_dirty(leaf);
2312
2313         ret = 0;
2314         if (slot == 0) {
2315                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2316                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2317         }
2318
2319         if (btrfs_leaf_free_space(root, leaf) < 0) {
2320                 btrfs_print_leaf(root, leaf);
2321                 BUG();
2322         }
2323
2324 out:
2325         return ret;
2326 }
2327
2328 /*
2329  * Given a key and some data, insert an item into the tree.
2330  * This does all the path init required, making room in the tree if needed.
2331  */
2332 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2333                       *root, struct btrfs_key *cpu_key, void *data, u32
2334                       data_size)
2335 {
2336         int ret = 0;
2337         struct btrfs_path *path;
2338         struct extent_buffer *leaf;
2339         unsigned long ptr;
2340
2341         path = btrfs_alloc_path();
2342         BUG_ON(!path);
2343         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2344         if (!ret) {
2345                 leaf = path->nodes[0];
2346                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2347                 write_extent_buffer(leaf, data, ptr, data_size);
2348                 btrfs_mark_buffer_dirty(leaf);
2349         }
2350         btrfs_free_path(path);
2351         return ret;
2352 }
2353
2354 /*
2355  * delete the pointer from a given node.
2356  *
2357  * If the delete empties a node, the node is removed from the tree,
2358  * continuing all the way the root if required.  The root is converted into
2359  * a leaf if all the nodes are emptied.
2360  */
2361 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2362                    struct btrfs_path *path, int level, int slot)
2363 {
2364         struct extent_buffer *parent = path->nodes[level];
2365         u32 nritems;
2366         int ret = 0;
2367         int wret;
2368
2369         nritems = btrfs_header_nritems(parent);
2370         if (slot != nritems -1) {
2371                 memmove_extent_buffer(parent,
2372                               btrfs_node_key_ptr_offset(slot),
2373                               btrfs_node_key_ptr_offset(slot + 1),
2374                               sizeof(struct btrfs_key_ptr) *
2375                               (nritems - slot - 1));
2376         }
2377         nritems--;
2378         btrfs_set_header_nritems(parent, nritems);
2379         if (nritems == 0 && parent == root->node) {
2380                 BUG_ON(btrfs_header_level(root->node) != 1);
2381                 /* just turn the root into a leaf and break */
2382                 btrfs_set_header_level(root->node, 0);
2383         } else if (slot == 0) {
2384                 struct btrfs_disk_key disk_key;
2385
2386                 btrfs_node_key(parent, &disk_key, 0);
2387                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2388                 if (wret)
2389                         ret = wret;
2390         }
2391         btrfs_mark_buffer_dirty(parent);
2392         return ret;
2393 }
2394
2395 /*
2396  * delete the item at the leaf level in path.  If that empties
2397  * the leaf, remove it from the tree
2398  */
2399 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2400                     struct btrfs_path *path, int slot, int nr)
2401 {
2402         struct extent_buffer *leaf;
2403         struct btrfs_item *item;
2404         int last_off;
2405         int dsize = 0;
2406         int ret = 0;
2407         int wret;
2408         int i;
2409         u32 nritems;
2410
2411         leaf = path->nodes[0];
2412         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
2413
2414         for (i = 0; i < nr; i++)
2415                 dsize += btrfs_item_size_nr(leaf, slot + i);
2416
2417         nritems = btrfs_header_nritems(leaf);
2418
2419         if (slot + nr != nritems) {
2420                 int i;
2421                 int data_end = leaf_data_end(root, leaf);
2422
2423                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2424                               data_end + dsize,
2425                               btrfs_leaf_data(leaf) + data_end,
2426                               last_off - data_end);
2427
2428                 for (i = slot + nr; i < nritems; i++) {
2429                         u32 ioff;
2430
2431                         item = btrfs_item_nr(leaf, i);
2432                         ioff = btrfs_item_offset(leaf, item);
2433                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2434                 }
2435
2436                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2437                               btrfs_item_nr_offset(slot + nr),
2438                               sizeof(struct btrfs_item) *
2439                               (nritems - slot - nr));
2440         }
2441         btrfs_set_header_nritems(leaf, nritems - nr);
2442         nritems -= nr;
2443
2444         /* delete the leaf if we've emptied it */
2445         if (nritems == 0) {
2446                 if (leaf == root->node) {
2447                         btrfs_set_header_level(leaf, 0);
2448                 } else {
2449                         u64 root_gen = btrfs_header_generation(path->nodes[1]);
2450                         clean_tree_block(trans, root, leaf);
2451                         wait_on_tree_block_writeback(root, leaf);
2452                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
2453                         if (wret)
2454                                 ret = wret;
2455                         wret = btrfs_free_extent(trans, root,
2456                                          leaf->start, leaf->len,
2457                                          btrfs_header_owner(path->nodes[1]),
2458                                          root_gen, 0, 0, 1);
2459                         if (wret)
2460                                 ret = wret;
2461                 }
2462         } else {
2463                 int used = leaf_space_used(leaf, 0, nritems);
2464                 if (slot == 0) {
2465                         struct btrfs_disk_key disk_key;
2466
2467                         btrfs_item_key(leaf, &disk_key, 0);
2468                         wret = fixup_low_keys(trans, root, path,
2469                                               &disk_key, 1);
2470                         if (wret)
2471                                 ret = wret;
2472                 }
2473
2474                 /* delete the leaf if it is mostly empty */
2475                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 4) {
2476                         /* push_leaf_left fixes the path.
2477                          * make sure the path still points to our leaf
2478                          * for possible call to del_ptr below
2479                          */
2480                         slot = path->slots[1];
2481                         extent_buffer_get(leaf);
2482
2483                         wret = push_leaf_left(trans, root, path, 1, 1);
2484                         if (wret < 0 && wret != -ENOSPC)
2485                                 ret = wret;
2486
2487                         if (path->nodes[0] == leaf &&
2488                             btrfs_header_nritems(leaf)) {
2489                                 wret = push_leaf_right(trans, root, path, 1, 1);
2490                                 if (wret < 0 && wret != -ENOSPC)
2491                                         ret = wret;
2492                         }
2493
2494                         if (btrfs_header_nritems(leaf) == 0) {
2495                                 u64 root_gen;
2496                                 u64 bytenr = leaf->start;
2497                                 u32 blocksize = leaf->len;
2498
2499                                 root_gen = btrfs_header_generation(
2500                                                            path->nodes[1]);
2501
2502                                 clean_tree_block(trans, root, leaf);
2503                                 wait_on_tree_block_writeback(root, leaf);
2504
2505                                 wret = del_ptr(trans, root, path, 1, slot);
2506                                 if (wret)
2507                                         ret = wret;
2508
2509                                 free_extent_buffer(leaf);
2510                                 wret = btrfs_free_extent(trans, root, bytenr,
2511                                              blocksize,
2512                                              btrfs_header_owner(path->nodes[1]),
2513                                              root_gen, 0, 0, 1);
2514                                 if (wret)
2515                                         ret = wret;
2516                         } else {
2517                                 btrfs_mark_buffer_dirty(leaf);
2518                                 free_extent_buffer(leaf);
2519                         }
2520                 } else {
2521                         btrfs_mark_buffer_dirty(leaf);
2522                 }
2523         }
2524         return ret;
2525 }
2526
2527 /*
2528  * walk up the tree as far as required to find the previous leaf.
2529  * returns 0 if it found something or 1 if there are no lesser leaves.
2530  * returns < 0 on io errors.
2531  */
2532 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2533 {
2534         u64 bytenr;
2535         int slot;
2536         int level = 1;
2537         struct extent_buffer *c;
2538         struct extent_buffer *next = NULL;
2539
2540         while(level < BTRFS_MAX_LEVEL) {
2541                 if (!path->nodes[level])
2542                         return 1;
2543
2544                 slot = path->slots[level];
2545                 c = path->nodes[level];
2546                 if (slot == 0) {
2547                         level++;
2548                         if (level == BTRFS_MAX_LEVEL)
2549                                 return 1;
2550                         continue;
2551                 }
2552                 slot--;
2553
2554                 bytenr = btrfs_node_blockptr(c, slot);
2555                 if (next)
2556                         free_extent_buffer(next);
2557
2558                 next = read_tree_block(root, bytenr,
2559                                        btrfs_level_size(root, level - 1));
2560                 break;
2561         }
2562         path->slots[level] = slot;
2563         while(1) {
2564                 level--;
2565                 c = path->nodes[level];
2566                 free_extent_buffer(c);
2567                 slot = btrfs_header_nritems(next);
2568                 if (slot != 0)
2569                         slot--;
2570                 path->nodes[level] = next;
2571                 path->slots[level] = slot;
2572                 if (!level)
2573                         break;
2574                 next = read_tree_block(root, btrfs_node_blockptr(next, slot),
2575                                        btrfs_level_size(root, level - 1));
2576         }
2577         return 0;
2578 }
2579
2580 /*
2581  * walk up the tree as far as required to find the next leaf.
2582  * returns 0 if it found something or 1 if there are no greater leaves.
2583  * returns < 0 on io errors.
2584  */
2585 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2586 {
2587         int slot;
2588         int level = 1;
2589         u64 bytenr;
2590         struct extent_buffer *c;
2591         struct extent_buffer *next = NULL;
2592
2593         while(level < BTRFS_MAX_LEVEL) {
2594                 if (!path->nodes[level])
2595                         return 1;
2596
2597                 slot = path->slots[level] + 1;
2598                 c = path->nodes[level];
2599                 if (slot >= btrfs_header_nritems(c)) {
2600                         level++;
2601                         if (level == BTRFS_MAX_LEVEL)
2602                                 return 1;
2603                         continue;
2604                 }
2605
2606                 bytenr = btrfs_node_blockptr(c, slot);
2607                 if (next)
2608                         free_extent_buffer(next);
2609
2610                 if (path->reada)
2611                         reada_for_search(root, path, level, slot, 0);
2612
2613                 next = read_tree_block(root, bytenr,
2614                                        btrfs_level_size(root, level -1));
2615                 break;
2616         }
2617         path->slots[level] = slot;
2618         while(1) {
2619                 level--;
2620                 c = path->nodes[level];
2621                 free_extent_buffer(c);
2622                 path->nodes[level] = next;
2623                 path->slots[level] = 0;
2624                 if (!level)
2625                         break;
2626                 if (path->reada)
2627                         reada_for_search(root, path, level, 0, 0);
2628                 next = read_tree_block(root, btrfs_node_blockptr(next, 0),
2629                                        btrfs_level_size(root, level - 1));
2630         }
2631         return 0;
2632 }
2633
2634 int btrfs_previous_item(struct btrfs_root *root,
2635                         struct btrfs_path *path, u64 min_objectid,
2636                         int type)
2637 {
2638         struct btrfs_key found_key;
2639         struct extent_buffer *leaf;
2640         int ret;
2641
2642         while(1) {
2643                 if (path->slots[0] == 0) {
2644                         ret = btrfs_prev_leaf(root, path);
2645                         if (ret != 0)
2646                                 return ret;
2647                 } else {
2648                         path->slots[0]--;
2649                 }
2650                 leaf = path->nodes[0];
2651                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2652                 if (found_key.type == type)
2653                         return 0;
2654         }
2655         return 1;
2656 }
2657