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         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
 126
 127         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 128         ret = btrfs_inc_ref(trans, new_root, buf);
 129         kfree(new_root);
 130
 131         if (ret)
 132                 return ret;
 133
 134         btrfs_mark_buffer_dirty(cow);
 135         *cow_ret = cow;
 136         return 0;
 137 }
 138
 139 int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 140                              struct btrfs_root *root,
 141                              struct extent_buffer *buf,
 142                              struct extent_buffer *parent, int parent_slot,
 143                              struct extent_buffer **cow_ret,
 144                              u64 search_start, u64 empty_size)
 145 {
 146         u64 root_gen;
 147         struct extent_buffer *cow;
 148         u32 nritems;
 149         int ret = 0;
 150         int different_trans = 0;
 151         int level;
 152         struct btrfs_key first_key;
 153
 154         if (root->ref_cows) {
 155                 root_gen = trans->transid;
 156         } else {
 157                 root_gen = 0;
 158         }
 159
 160         WARN_ON(root->ref_cows && trans->transid !=
 161                 root->fs_info->running_transaction->transid);
 162         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 163
 164         level = btrfs_header_level(buf);
 165         nritems = btrfs_header_nritems(buf);
 166         if (nritems) {
 167                 if (level == 0)
 168                         btrfs_item_key_to_cpu(buf, &first_key, 0);
 169                 else
 170                         btrfs_node_key_to_cpu(buf, &first_key, 0);
 171         } else {
 172                 first_key.objectid = 0;
 173         }
 174         cow = __btrfs_alloc_free_block(trans, root, buf->len,
 175                                      root->root_key.objectid,
 176                                      root_gen, first_key.objectid, level,
 177                                      search_start, empty_size);
 178         if (IS_ERR(cow))
 179                 return PTR_ERR(cow);
 180
 181         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 182         btrfs_set_header_bytenr(cow, cow->start);
 183         btrfs_set_header_generation(cow, trans->transid);
 184         btrfs_set_header_owner(cow, root->root_key.objectid);
 185         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
 186
 187         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 188         if (btrfs_header_generation(buf) != trans->transid) {
 189                 different_trans = 1;
 190                 ret = btrfs_inc_ref(trans, root, buf);
 191                 if (ret)
 192                         return ret;
 193         } else {
 194                 clean_tree_block(trans, root, buf);
 195         }
 196
 197         if (buf == root->node) {
 198                 root_gen = btrfs_header_generation(buf);
 199                 root->node = cow;
 200                 extent_buffer_get(cow);
 201                 if (buf != root->commit_root) {
 202                         btrfs_free_extent(trans, root, buf->start,
 203                                           buf->len, root->root_key.objectid,
 204                                           root_gen, 0, 0, 1);
 205                 }
 206                 free_extent_buffer(buf);
 207                 add_root_to_dirty_list(root);
 208         } else {
 209                 root_gen = btrfs_header_generation(parent);
 210                 btrfs_set_node_blockptr(parent, parent_slot,
 211                                         cow->start);
 212                 WARN_ON(trans->transid == 0);
 213                 btrfs_set_node_ptr_generation(parent, parent_slot,
 214                                               trans->transid);
 215                 btrfs_mark_buffer_dirty(parent);
 216                 WARN_ON(btrfs_header_generation(parent) != trans->transid);
 217                 btrfs_free_extent(trans, root, buf->start, buf->len,
 218                                   btrfs_header_owner(parent), root_gen,
 219                                   0, 0, 1);
 220         }
 221         free_extent_buffer(buf);
 222         btrfs_mark_buffer_dirty(cow);
 223         *cow_ret = cow;
 224         return 0;
 225 }
 226
 227 int btrfs_cow_block(struct btrfs_trans_handle *trans,
 228                     struct btrfs_root *root, struct extent_buffer *buf,
 229                     struct extent_buffer *parent, int parent_slot,
 230                     struct extent_buffer **cow_ret)
 231 {
 232         u64 search_start;
 233         int ret;
 234         /*
 235         if (trans->transaction != root->fs_info->running_transaction) {
 236                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 237                        root->fs_info->running_transaction->transid);
 238                 WARN_ON(1);
 239         }
 240         */
 241         if (trans->transid != root->fs_info->generation) {
 242                 printk(KERN_CRIT "trans %llu running %llu\n",
 243                         (unsigned long long)trans->transid,
 244                         (unsigned long long)root->fs_info->generation);
 245                 WARN_ON(1);
 246         }
 247         if (btrfs_header_generation(buf) == trans->transid) {
 248 #if 0
 249                 &&
 250             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
 251 #endif
 252                 *cow_ret = buf;
 253                 return 0;
 254         }
 255
 256         search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
 257         ret = __btrfs_cow_block(trans, root, buf, parent,
 258                                  parent_slot, cow_ret, search_start, 0);
 259         return ret;
 260 }
 261
 262 /*
 263 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 264 {
 265         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 266                 return 1;
 267         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 268                 return 1;
 269         return 0;
 270 }
 271 */
 272
 273 /*
 274  * compare two keys in a memcmp fashion
 275  */
 276 int btrfs_comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 277 {
 278         struct btrfs_key k1;
 279
 280         btrfs_disk_key_to_cpu(&k1, disk);
 281
 282         if (k1.objectid > k2->objectid)
 283                 return 1;
 284         if (k1.objectid < k2->objectid)
 285                 return -1;
 286         if (k1.type > k2->type)
 287                 return 1;
 288         if (k1.type < k2->type)
 289                 return -1;
 290         if (k1.offset > k2->offset)
 291                 return 1;
 292         if (k1.offset < k2->offset)
 293                 return -1;
 294         return 0;
 295 }
 296
 297
 298 #if 0
 299 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 300                        struct btrfs_root *root, struct extent_buffer *parent,
 301                        int start_slot, int cache_only, u64 *last_ret,
 302                        struct btrfs_key *progress)
 303 {
 304         struct extent_buffer *cur;
 305         struct extent_buffer *tmp;
 306         u64 blocknr;
 307         u64 search_start = *last_ret;
 308         u64 last_block = 0;
 309         u64 other;
 310         u32 parent_nritems;
 311         int end_slot;
 312         int i;
 313         int err = 0;
 314         int parent_level;
 315         int uptodate;
 316         u32 blocksize;
 317         int progress_passed = 0;
 318         struct btrfs_disk_key disk_key;
 319
 320         parent_level = btrfs_header_level(parent);
 321         if (cache_only && parent_level != 1)
 322                 return 0;
 323
 324         if (trans->transaction != root->fs_info->running_transaction) {
 325                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 326                        root->fs_info->running_transaction->transid);
 327                 WARN_ON(1);
 328         }
 329         if (trans->transid != root->fs_info->generation) {
 330                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 331                        root->fs_info->generation);
 332                 WARN_ON(1);
 333         }
 334
 335         parent_nritems = btrfs_header_nritems(parent);
 336         blocksize = btrfs_level_size(root, parent_level - 1);
 337         end_slot = parent_nritems;
 338
 339         if (parent_nritems == 1)
 340                 return 0;
 341
 342         for (i = start_slot; i < end_slot; i++) {
 343                 int close = 1;
 344
 345                 if (!parent->map_token) {
 346                         map_extent_buffer(parent,
 347                                         btrfs_node_key_ptr_offset(i),
 348                                         sizeof(struct btrfs_key_ptr),
 349                                         &parent->map_token, &parent->kaddr,
 350                                         &parent->map_start, &parent->map_len,
 351                                         KM_USER1);
 352                 }
 353                 btrfs_node_key(parent, &disk_key, i);
 354                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
 355                         continue;
 356
 357                 progress_passed = 1;
 358                 blocknr = btrfs_node_blockptr(parent, i);
 359                 if (last_block == 0)
 360                         last_block = blocknr;
 361
 362                 if (i > 0) {
 363                         other = btrfs_node_blockptr(parent, i - 1);
 364                         close = close_blocks(blocknr, other, blocksize);
 365                 }
 366                 if (close && i < end_slot - 2) {
 367                         other = btrfs_node_blockptr(parent, i + 1);
 368                         close = close_blocks(blocknr, other, blocksize);
 369                 }
 370                 if (close) {
 371                         last_block = blocknr;
 372                         continue;
 373                 }
 374                 if (parent->map_token) {
 375                         unmap_extent_buffer(parent, parent->map_token,
 376                                             KM_USER1);
 377                         parent->map_token = NULL;
 378                 }
 379
 380                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
 381                 if (cur)
 382                         uptodate = btrfs_buffer_uptodate(cur);
 383                 else
 384                         uptodate = 0;
 385                 if (!cur || !uptodate) {
 386                         if (cache_only) {
 387                                 free_extent_buffer(cur);
 388                                 continue;
 389                         }
 390                         if (!cur) {
 391                                 cur = read_tree_block(root, blocknr,
 392                                                          blocksize);
 393                         } else if (!uptodate) {
 394                                 btrfs_read_buffer(cur);
 395                         }
 396                 }
 397                 if (search_start == 0)
 398                         search_start = last_block;
 399
 400                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 401                                         &tmp, search_start,
 402                                         min(16 * blocksize,
 403                                             (end_slot - i) * blocksize));
 404                 if (err) {
 405                         free_extent_buffer(cur);
 406                         break;
 407                 }
 408                 search_start = tmp->start;
 409                 last_block = tmp->start;
 410                 *last_ret = search_start;
 411                 if (parent_level == 1)
 412                         btrfs_clear_buffer_defrag(tmp);
 413                 free_extent_buffer(tmp);
 414         }
 415         if (parent->map_token) {
 416                 unmap_extent_buffer(parent, parent->map_token,
 417                                     KM_USER1);
 418                 parent->map_token = NULL;
 419         }
 420         return err;
 421 }
 422 #endif
 423
 424 /*
 425  * The leaf data grows from end-to-front in the node.
 426  * this returns the address of the start of the last item,
 427  * which is the stop of the leaf data stack
 428  */
 429 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 430                                          struct extent_buffer *leaf)
 431 {
 432         u32 nr = btrfs_header_nritems(leaf);
 433         if (nr == 0)
 434                 return BTRFS_LEAF_DATA_SIZE(root);
 435         return btrfs_item_offset_nr(leaf, nr - 1);
 436 }
 437
 438 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 439                       int level)
 440 {
 441         struct extent_buffer *parent = NULL;
 442         struct extent_buffer *node = path->nodes[level];
 443         struct btrfs_disk_key parent_key;
 444         struct btrfs_disk_key node_key;
 445         int parent_slot;
 446         int slot;
 447         struct btrfs_key cpukey;
 448         u32 nritems = btrfs_header_nritems(node);
 449
 450         if (path->nodes[level + 1])
 451                 parent = path->nodes[level + 1];
 452
 453         slot = path->slots[level];
 454         BUG_ON(nritems == 0);
 455         if (parent) {
 456                 parent_slot = path->slots[level + 1];
 457                 btrfs_node_key(parent, &parent_key, parent_slot);
 458                 btrfs_node_key(node, &node_key, 0);
 459                 BUG_ON(memcmp(&parent_key, &node_key,
 460                               sizeof(struct btrfs_disk_key)));
 461                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 462                        btrfs_header_bytenr(node));
 463         }
 464         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 465         if (slot != 0) {
 466                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 467                 btrfs_node_key(node, &node_key, slot);
 468                 BUG_ON(btrfs_comp_keys(&node_key, &cpukey) <= 0);
 469         }
 470         if (slot < nritems - 1) {
 471                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 472                 btrfs_node_key(node, &node_key, slot);
 473                 BUG_ON(btrfs_comp_keys(&node_key, &cpukey) >= 0);
 474         }
 475         return 0;
 476 }
 477
 478 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 479                       int level)
 480 {
 481         struct extent_buffer *leaf = path->nodes[level];
 482         struct extent_buffer *parent = NULL;
 483         int parent_slot;
 484         struct btrfs_key cpukey;
 485         struct btrfs_disk_key parent_key;
 486         struct btrfs_disk_key leaf_key;
 487         int slot = path->slots[0];
 488
 489         u32 nritems = btrfs_header_nritems(leaf);
 490
 491         if (path->nodes[level + 1])
 492                 parent = path->nodes[level + 1];
 493
 494         if (nritems == 0)
 495                 return 0;
 496
 497         if (parent) {
 498                 parent_slot = path->slots[level + 1];
 499                 btrfs_node_key(parent, &parent_key, parent_slot);
 500                 btrfs_item_key(leaf, &leaf_key, 0);
 501
 502                 BUG_ON(memcmp(&parent_key, &leaf_key,
 503                        sizeof(struct btrfs_disk_key)));
 504                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 505                        btrfs_header_bytenr(leaf));
 506         }
 507 #if 0
 508         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 509                 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
 510                 btrfs_item_key(leaf, &leaf_key, i);
 511                 if (comp_keys(&leaf_key, &cpukey) >= 0) {
 512                         btrfs_print_leaf(root, leaf);
 513                         printk("slot %d offset bad key\n", i);
 514                         BUG_ON(1);
 515                 }
 516                 if (btrfs_item_offset_nr(leaf, i) !=
 517                         btrfs_item_end_nr(leaf, i + 1)) {
 518                         btrfs_print_leaf(root, leaf);
 519                         printk("slot %d offset bad\n", i);
 520                         BUG_ON(1);
 521                 }
 522                 if (i == 0) {
 523                         if (btrfs_item_offset_nr(leaf, i) +
 524                                btrfs_item_size_nr(leaf, i) !=
 525                                BTRFS_LEAF_DATA_SIZE(root)) {
 526                                 btrfs_print_leaf(root, leaf);
 527                                 printk("slot %d first offset bad\n", i);
 528                                 BUG_ON(1);
 529                         }
 530                 }
 531         }
 532         if (nritems > 0) {
 533                 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
 534                                 btrfs_print_leaf(root, leaf);
 535                                 printk("slot %d bad size \n", nritems - 1);
 536                                 BUG_ON(1);
 537                 }
 538         }
 539 #endif
 540         if (slot != 0 && slot < nritems - 1) {
 541                 btrfs_item_key(leaf, &leaf_key, slot);
 542                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 543                 if (btrfs_comp_keys(&leaf_key, &cpukey) <= 0) {
 544                         btrfs_print_leaf(root, leaf);
 545                         printk("slot %d offset bad key\n", slot);
 546                         BUG_ON(1);
 547                 }
 548                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 549                        btrfs_item_end_nr(leaf, slot)) {
 550                         btrfs_print_leaf(root, leaf);
 551                         printk("slot %d offset bad\n", slot);
 552                         BUG_ON(1);
 553                 }
 554         }
 555         if (slot < nritems - 1) {
 556                 btrfs_item_key(leaf, &leaf_key, slot);
 557                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 558                 BUG_ON(btrfs_comp_keys(&leaf_key, &cpukey) >= 0);
 559                 if (btrfs_item_offset_nr(leaf, slot) !=
 560                         btrfs_item_end_nr(leaf, slot + 1)) {
 561                         btrfs_print_leaf(root, leaf);
 562                         printk("slot %d offset bad\n", slot);
 563                         BUG_ON(1);
 564                 }
 565         }
 566         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 567                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 568         return 0;
 569 }
 570
 571 static int noinline check_block(struct btrfs_root *root,
 572                                 struct btrfs_path *path, int level)
 573 {
 574         return 0;
 575 #if 0
 576         struct extent_buffer *buf = path->nodes[level];
 577
 578         if (memcmp_extent_buffer(buf, root->fs_info->fsid,
 579                                  (unsigned long)btrfs_header_fsid(buf),
 580                                  BTRFS_FSID_SIZE)) {
 581                 printk("warning bad block %Lu\n", buf->start);
 582                 return 1;
 583         }
 584 #endif
 585         if (level == 0)
 586                 return check_leaf(root, path, level);
 587         return check_node(root, path, level);
 588 }
 589
 590 /*
 591  * search for key in the extent_buffer.  The items start at offset p,
 592  * and they are item_size apart.  There are 'max' items in p.
 593  *
 594  * the slot in the array is returned via slot, and it points to
 595  * the place where you would insert key if it is not found in
 596  * the array.
 597  *
 598  * slot may point to max if the key is bigger than all of the keys
 599  */
 600 static int generic_bin_search(struct extent_buffer *eb, unsigned long p,
 601                               int item_size, struct btrfs_key *key,
 602                               int max, int *slot)
 603 {
 604         int low = 0;
 605         int high = max;
 606         int mid;
 607         int ret;
 608         unsigned long offset;
 609         struct btrfs_disk_key *tmp;
 610
 611         while(low < high) {
 612                 mid = (low + high) / 2;
 613                 offset = p + mid * item_size;
 614
 615                 tmp = (struct btrfs_disk_key *)(eb->data + offset);
 616                 ret = btrfs_comp_keys(tmp, key);
 617
 618                 if (ret < 0)
 619                         low = mid + 1;
 620                 else if (ret > 0)
 621                         high = mid;
 622                 else {
 623                         *slot = mid;
 624                         return 0;
 625                 }
 626         }
 627         *slot = low;
 628         return 1;
 629 }
 630
 631 /*
 632  * simple bin_search frontend that does the right thing for
 633  * leaves vs nodes
 634  */
 635 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 636                       int level, int *slot)
 637 {
 638         if (level == 0) {
 639                 return generic_bin_search(eb,
 640                                           offsetof(struct btrfs_leaf, items),
 641                                           sizeof(struct btrfs_item),
 642                                           key, btrfs_header_nritems(eb),
 643                                           slot);
 644         } else {
 645                 return generic_bin_search(eb,
 646                                           offsetof(struct btrfs_node, ptrs),
 647                                           sizeof(struct btrfs_key_ptr),
 648                                           key, btrfs_header_nritems(eb),
 649                                           slot);
 650         }
 651         return -1;
 652 }
 653
 654 static struct extent_buffer *read_node_slot(struct btrfs_root *root,
 655                                    struct extent_buffer *parent, int slot)
 656 {
 657         if (slot < 0)
 658                 return NULL;
 659         if (slot >= btrfs_header_nritems(parent))
 660                 return NULL;
 661         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 662                        btrfs_level_size(root, btrfs_header_level(parent) - 1));
 663 }
 664
 665 static int balance_level(struct btrfs_trans_handle *trans,
 666                          struct btrfs_root *root,
 667                          struct btrfs_path *path, int level)
 668 {
 669         struct extent_buffer *right = NULL;
 670         struct extent_buffer *mid;
 671         struct extent_buffer *left = NULL;
 672         struct extent_buffer *parent = NULL;
 673         int ret = 0;
 674         int wret;
 675         int pslot;
 676         int orig_slot = path->slots[level];
 677         int err_on_enospc = 0;
 678         u64 orig_ptr;
 679
 680         if (level == 0)
 681                 return 0;
 682
 683         mid = path->nodes[level];
 684         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 685
 686         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 687
 688         if (level < BTRFS_MAX_LEVEL - 1)
 689                 parent = path->nodes[level + 1];
 690         pslot = path->slots[level + 1];
 691
 692         /*
 693          * deal with the case where there is only one pointer in the root
 694          * by promoting the node below to a root
 695          */
 696         if (!parent) {
 697                 struct extent_buffer *child;
 698
 699                 if (btrfs_header_nritems(mid) != 1)
 700                         return 0;
 701
 702                 /* promote the child to a root */
 703                 child = read_node_slot(root, mid, 0);
 704                 BUG_ON(!child);
 705                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
 706                 BUG_ON(ret);
 707
 708                 root->node = child;
 709                 add_root_to_dirty_list(root);
 710                 path->nodes[level] = NULL;
 711                 clean_tree_block(trans, root, mid);
 712                 wait_on_tree_block_writeback(root, mid);
 713                 /* once for the path */
 714                 free_extent_buffer(mid);
 715                 ret = btrfs_free_extent(trans, root, mid->start, mid->len,
 716                                         root->root_key.objectid,
 717                                         btrfs_header_generation(mid), 0, 0, 1);
 718                 /* once for the root ptr */
 719                 free_extent_buffer(mid);
 720                 return ret;
 721         }
 722         if (btrfs_header_nritems(mid) >
 723             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 724                 return 0;
 725
 726         if (btrfs_header_nritems(mid) < 2)
 727                 err_on_enospc = 1;
 728
 729         left = read_node_slot(root, parent, pslot - 1);
 730         if (left) {
 731                 wret = btrfs_cow_block(trans, root, left,
 732                                        parent, pslot - 1, &left);
 733                 if (wret) {
 734                         ret = wret;
 735                         goto enospc;
 736                 }
 737         }
 738         right = read_node_slot(root, parent, pslot + 1);
 739         if (right) {
 740                 wret = btrfs_cow_block(trans, root, right,
 741                                        parent, pslot + 1, &right);
 742                 if (wret) {
 743                         ret = wret;
 744                         goto enospc;
 745                 }
 746         }
 747
 748         /* first, try to make some room in the middle buffer */
 749         if (left) {
 750                 orig_slot += btrfs_header_nritems(left);
 751                 wret = push_node_left(trans, root, left, mid);
 752                 if (wret < 0)
 753                         ret = wret;
 754                 if (btrfs_header_nritems(mid) < 2)
 755                         err_on_enospc = 1;
 756         }
 757
 758         /*
 759          * then try to empty the right most buffer into the middle
 760          */
 761         if (right) {
 762                 wret = push_node_left(trans, root, mid, right);
 763                 if (wret < 0 && wret != -ENOSPC)
 764                         ret = wret;
 765                 if (btrfs_header_nritems(right) == 0) {
 766                         u64 bytenr = right->start;
 767                         u64 generation = btrfs_header_generation(parent);
 768                         u32 blocksize = right->len;
 769
 770                         clean_tree_block(trans, root, right);
 771                         wait_on_tree_block_writeback(root, right);
 772                         free_extent_buffer(right);
 773                         right = NULL;
 774                         wret = del_ptr(trans, root, path, level + 1, pslot +
 775                                        1);
 776                         if (wret)
 777                                 ret = wret;
 778                         wret = btrfs_free_extent(trans, root, bytenr,
 779                                                  blocksize,
 780                                                  btrfs_header_owner(parent),
 781                                                  generation, 0, 0, 1);
 782                         if (wret)
 783                                 ret = wret;
 784                 } else {
 785                         struct btrfs_disk_key right_key;
 786                         btrfs_node_key(right, &right_key, 0);
 787                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 788                         btrfs_mark_buffer_dirty(parent);
 789                 }
 790         }
 791         if (btrfs_header_nritems(mid) == 1) {
 792                 /*
 793                  * we're not allowed to leave a node with one item in the
 794                  * tree during a delete.  A deletion from lower in the tree
 795                  * could try to delete the only pointer in this node.
 796                  * So, pull some keys from the left.
 797                  * There has to be a left pointer at this point because
 798                  * otherwise we would have pulled some pointers from the
 799                  * right
 800                  */
 801                 BUG_ON(!left);
 802                 wret = balance_node_right(trans, root, mid, left);
 803                 if (wret < 0) {
 804                         ret = wret;
 805                         goto enospc;
 806                 }
 807                 BUG_ON(wret == 1);
 808         }
 809         if (btrfs_header_nritems(mid) == 0) {
 810                 /* we've managed to empty the middle node, drop it */
 811                 u64 root_gen = btrfs_header_generation(parent);
 812                 u64 bytenr = mid->start;
 813                 u32 blocksize = mid->len;
 814                 clean_tree_block(trans, root, mid);
 815                 wait_on_tree_block_writeback(root, mid);
 816                 free_extent_buffer(mid);
 817                 mid = NULL;
 818                 wret = del_ptr(trans, root, path, level + 1, pslot);
 819                 if (wret)
 820                         ret = wret;
 821                 wret = btrfs_free_extent(trans, root, bytenr, blocksize,
 822                                          btrfs_header_owner(parent),
 823                                          root_gen, 0, 0, 1);
 824                 if (wret)
 825                         ret = wret;
 826         } else {
 827                 /* update the parent key to reflect our changes */
 828                 struct btrfs_disk_key mid_key;
 829                 btrfs_node_key(mid, &mid_key, 0);
 830                 btrfs_set_node_key(parent, &mid_key, pslot);
 831                 btrfs_mark_buffer_dirty(parent);
 832         }
 833
 834         /* update the path */
 835         if (left) {
 836                 if (btrfs_header_nritems(left) > orig_slot) {
 837                         extent_buffer_get(left);
 838                         path->nodes[level] = left;
 839                         path->slots[level + 1] -= 1;
 840                         path->slots[level] = orig_slot;
 841                         if (mid)
 842                                 free_extent_buffer(mid);
 843                 } else {
 844                         orig_slot -= btrfs_header_nritems(left);
 845                         path->slots[level] = orig_slot;
 846                 }
 847         }
 848         /* double check we haven't messed things up */
 849         check_block(root, path, level);
 850         if (orig_ptr !=
 851             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 852                 BUG();
 853 enospc:
 854         if (right)
 855                 free_extent_buffer(right);
 856         if (left)
 857                 free_extent_buffer(left);
 858         return ret;
 859 }
 860
 861 /* returns zero if the push worked, non-zero otherwise */
 862 static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
 863                                           struct btrfs_root *root,
 864                                           struct btrfs_path *path, int level)
 865 {
 866         struct extent_buffer *right = NULL;
 867         struct extent_buffer *mid;
 868         struct extent_buffer *left = NULL;
 869         struct extent_buffer *parent = NULL;
 870         int ret = 0;
 871         int wret;
 872         int pslot;
 873         int orig_slot = path->slots[level];
 874         u64 orig_ptr;
 875
 876         if (level == 0)
 877                 return 1;
 878
 879         mid = path->nodes[level];
 880         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 881         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 882
 883         if (level < BTRFS_MAX_LEVEL - 1)
 884                 parent = path->nodes[level + 1];
 885         pslot = path->slots[level + 1];
 886
 887         if (!parent)
 888                 return 1;
 889
 890         left = read_node_slot(root, parent, pslot - 1);
 891
 892         /* first, try to make some room in the middle buffer */
 893         if (left) {
 894                 u32 left_nr;
 895                 left_nr = btrfs_header_nritems(left);
 896                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 897                         wret = 1;
 898                 } else {
 899                         ret = btrfs_cow_block(trans, root, left, parent,
 900                                               pslot - 1, &left);
 901                         if (ret)
 902                                 wret = 1;
 903                         else {
 904                                 wret = push_node_left(trans, root,
 905                                                       left, mid);
 906                         }
 907                 }
 908                 if (wret < 0)
 909                         ret = wret;
 910                 if (wret == 0) {
 911                         struct btrfs_disk_key disk_key;
 912                         orig_slot += left_nr;
 913                         btrfs_node_key(mid, &disk_key, 0);
 914                         btrfs_set_node_key(parent, &disk_key, pslot);
 915                         btrfs_mark_buffer_dirty(parent);
 916                         if (btrfs_header_nritems(left) > orig_slot) {
 917                                 path->nodes[level] = left;
 918                                 path->slots[level + 1] -= 1;
 919                                 path->slots[level] = orig_slot;
 920                                 free_extent_buffer(mid);
 921                         } else {
 922                                 orig_slot -=
 923                                         btrfs_header_nritems(left);
 924                                 path->slots[level] = orig_slot;
 925                                 free_extent_buffer(left);
 926                         }
 927                         return 0;
 928                 }
 929                 free_extent_buffer(left);
 930         }
 931         right= read_node_slot(root, parent, pslot + 1);
 932
 933         /*
 934          * then try to empty the right most buffer into the middle
 935          */
 936         if (right) {
 937                 u32 right_nr;
 938                 right_nr = btrfs_header_nritems(right);
 939                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 940                         wret = 1;
 941                 } else {
 942                         ret = btrfs_cow_block(trans, root, right,
 943                                               parent, pslot + 1,
 944                                               &right);
 945                         if (ret)
 946                                 wret = 1;
 947                         else {
 948                                 wret = balance_node_right(trans, root,
 949                                                           right, mid);
 950                         }
 951                 }
 952                 if (wret < 0)
 953                         ret = wret;
 954                 if (wret == 0) {
 955                         struct btrfs_disk_key disk_key;
 956
 957                         btrfs_node_key(right, &disk_key, 0);
 958                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
 959                         btrfs_mark_buffer_dirty(parent);
 960
 961                         if (btrfs_header_nritems(mid) <= orig_slot) {
 962                                 path->nodes[level] = right;
 963                                 path->slots[level + 1] += 1;
 964                                 path->slots[level] = orig_slot -
 965                                         btrfs_header_nritems(mid);
 966                                 free_extent_buffer(mid);
 967                         } else {
 968                                 free_extent_buffer(right);
 969                         }
 970                         return 0;
 971                 }
 972                 free_extent_buffer(right);
 973         }
 974         return 1;
 975 }
 976
 977 /*
 978  * readahead one full node of leaves
 979  */
 980 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 981                              int level, int slot, u64 objectid)
 982 {
 983         struct extent_buffer *node;
 984         struct btrfs_disk_key disk_key;
 985         u32 nritems;
 986         u64 search;
 987         u64 lowest_read;
 988         u64 highest_read;
 989         u64 nread = 0;
 990         int direction = path->reada;
 991         struct extent_buffer *eb;
 992         u32 nr;
 993         u32 blocksize;
 994         u32 nscan = 0;
 995
 996         if (level != 1)
 997                 return;
 998
 999         if (!path->nodes[level])
1000                 return;
1001
1002         node = path->nodes[level];
1003         search = btrfs_node_blockptr(node, slot);
1004         blocksize = btrfs_level_size(root, level - 1);
1005         eb = btrfs_find_tree_block(root, search, blocksize);
1006         if (eb) {
1007                 free_extent_buffer(eb);
1008                 return;
1009         }
1010
1011         highest_read = search;
1012         lowest_read = search;
1013
1014         nritems = btrfs_header_nritems(node);
1015         nr = slot;
1016         while(1) {
1017                 if (direction < 0) {
1018                         if (nr == 0)
1019                                 break;
1020                         nr--;
1021                 } else if (direction > 0) {
1022                         nr++;
1023                         if (nr >= nritems)
1024                                 break;
1025                 }
1026                 if (path->reada < 0 && objectid) {
1027                         btrfs_node_key(node, &disk_key, nr);
1028                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1029                                 break;
1030                 }
1031                 search = btrfs_node_blockptr(node, nr);
1032                 if ((search >= lowest_read && search <= highest_read) ||
1033                     (search < lowest_read && lowest_read - search <= 32768) ||
1034                     (search > highest_read && search - highest_read <= 32768)) {
1035                         readahead_tree_block(root, search, blocksize);
1036                         nread += blocksize;
1037                 }
1038                 nscan++;
1039                 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
1040                         break;
1041                 if(nread > (1024 * 1024) || nscan > 128)
1042                         break;
1043
1044                 if (search < lowest_read)
1045                         lowest_read = search;
1046                 if (search > highest_read)
1047                         highest_read = search;
1048         }
1049 }
1050
1051 /*
1052  * look for key in the tree.  path is filled in with nodes along the way
1053  * if key is found, we return zero and you can find the item in the leaf
1054  * level of the path (level 0)
1055  *
1056  * If the key isn't found, the path points to the slot where it should
1057  * be inserted, and 1 is returned.  If there are other errors during the
1058  * search a negative error number is returned.
1059  *
1060  * if ins_len > 0, nodes and leaves will be split as we walk down the
1061  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
1062  * possible)
1063  */
1064 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1065                       *root, struct btrfs_key *key, struct btrfs_path *p, int
1066                       ins_len, int cow)
1067 {
1068         struct extent_buffer *b;
1069         u64 bytenr;
1070         u64 ptr_gen;
1071         int slot;
1072         int ret;
1073         int level;
1074         int should_reada = p->reada;
1075         u8 lowest_level = 0;
1076
1077         lowest_level = p->lowest_level;
1078         WARN_ON(lowest_level && ins_len);
1079         WARN_ON(p->nodes[0] != NULL);
1080         /*
1081         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
1082         */
1083 again:
1084         b = root->node;
1085         extent_buffer_get(b);
1086         while (b) {
1087                 level = btrfs_header_level(b);
1088                 if (cow) {
1089                         int wret;
1090                         wret = btrfs_cow_block(trans, root, b,
1091                                                p->nodes[level + 1],
1092                                                p->slots[level + 1],
1093                                                &b);
1094                         if (wret) {
1095                                 free_extent_buffer(b);
1096                                 return wret;
1097                         }
1098                 }
1099                 BUG_ON(!cow && ins_len);
1100                 if (level != btrfs_header_level(b))
1101                         WARN_ON(1);
1102                 level = btrfs_header_level(b);
1103                 p->nodes[level] = b;
1104                 ret = check_block(root, p, level);
1105                 if (ret)
1106                         return -1;
1107                 ret = bin_search(b, key, level, &slot);
1108                 if (level != 0) {
1109                         if (ret && slot > 0)
1110                                 slot -= 1;
1111                         p->slots[level] = slot;
1112                         if (ins_len > 0 && btrfs_header_nritems(b) >=
1113                             BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1114                                 int sret = split_node(trans, root, p, level);
1115                                 BUG_ON(sret > 0);
1116                                 if (sret)
1117                                         return sret;
1118                                 b = p->nodes[level];
1119                                 slot = p->slots[level];
1120                         } else if (ins_len < 0) {
1121                                 int sret = balance_level(trans, root, p,
1122                                                          level);
1123                                 if (sret)
1124                                         return sret;
1125                                 b = p->nodes[level];
1126                                 if (!b) {
1127                                         btrfs_release_path(NULL, p);
1128                                         goto again;
1129                                 }
1130                                 slot = p->slots[level];
1131                                 BUG_ON(btrfs_header_nritems(b) == 1);
1132                         }
1133                         /* this is only true while dropping a snapshot */
1134                         if (level == lowest_level)
1135                                 break;
1136                         bytenr = btrfs_node_blockptr(b, slot);
1137                         ptr_gen = btrfs_node_ptr_generation(b, slot);
1138                         if (should_reada)
1139                                 reada_for_search(root, p, level, slot,
1140                                                  key->objectid);
1141                         b = read_tree_block(root, bytenr,
1142                                             btrfs_level_size(root, level - 1));
1143                         if (ptr_gen != btrfs_header_generation(b)) {
1144                                 printk("block %llu bad gen wanted %llu "
1145                                        "found %llu\n",
1146                                 (unsigned long long)b->start,
1147                                 (unsigned long long)ptr_gen,
1148                                 (unsigned long long)btrfs_header_generation(b));
1149                         }
1150                 } else {
1151                         p->slots[level] = slot;
1152                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1153                             sizeof(struct btrfs_item) + ins_len) {
1154                                 int sret = split_leaf(trans, root, key,
1155                                                       p, ins_len, ret == 0);
1156                                 BUG_ON(sret > 0);
1157                                 if (sret)
1158                                         return sret;
1159                         }
1160                         return ret;
1161                 }
1162         }
1163         return 1;
1164 }
1165
1166 /*
1167  * adjust the pointers going up the tree, starting at level
1168  * making sure the right key of each node is points to 'key'.
1169  * This is used after shifting pointers to the left, so it stops
1170  * fixing up pointers when a given leaf/node is not in slot 0 of the
1171  * higher levels
1172  *
1173  * If this fails to write a tree block, it returns -1, but continues
1174  * fixing up the blocks in ram so the tree is consistent.
1175  */
1176 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1177                           struct btrfs_root *root, struct btrfs_path *path,
1178                           struct btrfs_disk_key *key, int level)
1179 {
1180         int i;
1181         int ret = 0;
1182         struct extent_buffer *t;
1183
1184         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1185                 int tslot = path->slots[i];
1186                 if (!path->nodes[i])
1187                         break;
1188                 t = path->nodes[i];
1189                 btrfs_set_node_key(t, key, tslot);
1190                 btrfs_mark_buffer_dirty(path->nodes[i]);
1191                 if (tslot != 0)
1192                         break;
1193         }
1194         return ret;
1195 }
1196
1197 /*
1198  * try to push data from one node into the next node left in the
1199  * tree.
1200  *
1201  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1202  * error, and > 0 if there was no room in the left hand block.
1203  */
1204 static int push_node_left(struct btrfs_trans_handle *trans,
1205                           struct btrfs_root *root, struct extent_buffer *dst,
1206                           struct extent_buffer *src)
1207 {
1208         int push_items = 0;
1209         int src_nritems;
1210         int dst_nritems;
1211         int ret = 0;
1212
1213         src_nritems = btrfs_header_nritems(src);
1214         dst_nritems = btrfs_header_nritems(dst);
1215         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1216         WARN_ON(btrfs_header_generation(src) != trans->transid);
1217         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1218
1219         if (push_items <= 0) {
1220                 return 1;
1221         }
1222
1223         if (src_nritems < push_items)
1224                 push_items = src_nritems;
1225
1226         copy_extent_buffer(dst, src,
1227                            btrfs_node_key_ptr_offset(dst_nritems),
1228                            btrfs_node_key_ptr_offset(0),
1229                            push_items * sizeof(struct btrfs_key_ptr));
1230
1231         if (push_items < src_nritems) {
1232                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1233                                       btrfs_node_key_ptr_offset(push_items),
1234                                       (src_nritems - push_items) *
1235                                       sizeof(struct btrfs_key_ptr));
1236         }
1237         btrfs_set_header_nritems(src, src_nritems - push_items);
1238         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1239         btrfs_mark_buffer_dirty(src);
1240         btrfs_mark_buffer_dirty(dst);
1241         return ret;
1242 }
1243
1244 /*
1245  * try to push data from one node into the next node right in the
1246  * tree.
1247  *
1248  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1249  * error, and > 0 if there was no room in the right hand block.
1250  *
1251  * this will  only push up to 1/2 the contents of the left node over
1252  */
1253 static int balance_node_right(struct btrfs_trans_handle *trans,
1254                               struct btrfs_root *root,
1255                               struct extent_buffer *dst,
1256                               struct extent_buffer *src)
1257 {
1258         int push_items = 0;
1259         int max_push;
1260         int src_nritems;
1261         int dst_nritems;
1262         int ret = 0;
1263
1264         WARN_ON(btrfs_header_generation(src) != trans->transid);
1265         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1266
1267         src_nritems = btrfs_header_nritems(src);
1268         dst_nritems = btrfs_header_nritems(dst);
1269         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1270         if (push_items <= 0)
1271                 return 1;
1272
1273         max_push = src_nritems / 2 + 1;
1274         /* don't try to empty the node */
1275         if (max_push >= src_nritems)
1276                 return 1;
1277
1278         if (max_push < push_items)
1279                 push_items = max_push;
1280
1281         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1282                                       btrfs_node_key_ptr_offset(0),
1283                                       (dst_nritems) *
1284                                       sizeof(struct btrfs_key_ptr));
1285
1286         copy_extent_buffer(dst, src,
1287                            btrfs_node_key_ptr_offset(0),
1288                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1289                            push_items * sizeof(struct btrfs_key_ptr));
1290
1291         btrfs_set_header_nritems(src, src_nritems - push_items);
1292         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1293
1294         btrfs_mark_buffer_dirty(src);
1295         btrfs_mark_buffer_dirty(dst);
1296         return ret;
1297 }
1298
1299 /*
1300  * helper function to insert a new root level in the tree.
1301  * A new node is allocated, and a single item is inserted to
1302  * point to the existing root
1303  *
1304  * returns zero on success or < 0 on failure.
1305  */
1306 static int noinline insert_new_root(struct btrfs_trans_handle *trans,
1307                            struct btrfs_root *root,
1308                            struct btrfs_path *path, int level)
1309 {
1310         u64 root_gen;
1311         u64 lower_gen;
1312         struct extent_buffer *lower;
1313         struct extent_buffer *c;
1314         struct btrfs_disk_key lower_key;
1315
1316         BUG_ON(path->nodes[level]);
1317         BUG_ON(path->nodes[level-1] != root->node);
1318
1319         if (root->ref_cows)
1320                 root_gen = trans->transid;
1321         else
1322                 root_gen = 0;
1323
1324         lower = path->nodes[level-1];
1325         if (level == 1)
1326                 btrfs_item_key(lower, &lower_key, 0);
1327         else
1328                 btrfs_node_key(lower, &lower_key, 0);
1329
1330         c = __btrfs_alloc_free_block(trans, root, root->nodesize,
1331                                    root->root_key.objectid,
1332                                    root_gen, lower_key.objectid, level,
1333                                    root->node->start, 0);
1334         if (IS_ERR(c))
1335                 return PTR_ERR(c);
1336         memset_extent_buffer(c, 0, 0, root->nodesize);
1337         btrfs_set_header_nritems(c, 1);
1338         btrfs_set_header_level(c, level);
1339         btrfs_set_header_bytenr(c, c->start);
1340         btrfs_set_header_generation(c, trans->transid);
1341         btrfs_set_header_owner(c, root->root_key.objectid);
1342
1343         write_extent_buffer(c, root->fs_info->fsid,
1344                             (unsigned long)btrfs_header_fsid(c),
1345                             BTRFS_FSID_SIZE);
1346         btrfs_set_node_key(c, &lower_key, 0);
1347         btrfs_set_node_blockptr(c, 0, lower->start);
1348         lower_gen = btrfs_header_generation(lower);
1349         WARN_ON(lower_gen == 0);
1350
1351         btrfs_set_node_ptr_generation(c, 0, lower_gen);
1352
1353         btrfs_mark_buffer_dirty(c);
1354
1355         /* the super has an extra ref to root->node */
1356         free_extent_buffer(root->node);
1357         root->node = c;
1358         add_root_to_dirty_list(root);
1359         extent_buffer_get(c);
1360         path->nodes[level] = c;
1361         path->slots[level] = 0;
1362
1363         if (root->ref_cows && lower_gen != trans->transid) {
1364                 struct btrfs_path *back_path = btrfs_alloc_path();
1365                 int ret;
1366                 ret = btrfs_insert_extent_backref(trans,
1367                                                   root->fs_info->extent_root,
1368                                                   path, lower->start,
1369                                                   root->root_key.objectid,
1370                                                   trans->transid, 0, 0);
1371                 BUG_ON(ret);
1372                 btrfs_free_path(back_path);
1373         }
1374         return 0;
1375 }
1376
1377 /*
1378  * worker function to insert a single pointer in a node.
1379  * the node should have enough room for the pointer already
1380  *
1381  * slot and level indicate where you want the key to go, and
1382  * blocknr is the block the key points to.
1383  *
1384  * returns zero on success and < 0 on any error
1385  */
1386 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1387                       *root, struct btrfs_path *path, struct btrfs_disk_key
1388                       *key, u64 bytenr, int slot, int level)
1389 {
1390         struct extent_buffer *lower;
1391         int nritems;
1392
1393         BUG_ON(!path->nodes[level]);
1394         lower = path->nodes[level];
1395         nritems = btrfs_header_nritems(lower);
1396         if (slot > nritems)
1397                 BUG();
1398         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1399                 BUG();
1400         if (slot != nritems) {
1401                 memmove_extent_buffer(lower,
1402                               btrfs_node_key_ptr_offset(slot + 1),
1403                               btrfs_node_key_ptr_offset(slot),
1404                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1405         }
1406         btrfs_set_node_key(lower, key, slot);
1407         btrfs_set_node_blockptr(lower, slot, bytenr);
1408         WARN_ON(trans->transid == 0);
1409         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
1410         btrfs_set_header_nritems(lower, nritems + 1);
1411         btrfs_mark_buffer_dirty(lower);
1412         return 0;
1413 }
1414
1415 /*
1416  * split the node at the specified level in path in two.
1417  * The path is corrected to point to the appropriate node after the split
1418  *
1419  * Before splitting this tries to make some room in the node by pushing
1420  * left and right, if either one works, it returns right away.
1421  *
1422  * returns 0 on success and < 0 on failure
1423  */
1424 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1425                       *root, struct btrfs_path *path, int level)
1426 {
1427         u64 root_gen;
1428         struct extent_buffer *c;
1429         struct extent_buffer *split;
1430         struct btrfs_disk_key disk_key;
1431         int mid;
1432         int ret;
1433         int wret;
1434         u32 c_nritems;
1435
1436         c = path->nodes[level];
1437         WARN_ON(btrfs_header_generation(c) != trans->transid);
1438         if (c == root->node) {
1439                 /* trying to split the root, lets make a new one */
1440                 ret = insert_new_root(trans, root, path, level + 1);
1441                 if (ret)
1442                         return ret;
1443         } else {
1444                 ret = push_nodes_for_insert(trans, root, path, level);
1445                 c = path->nodes[level];
1446                 if (!ret && btrfs_header_nritems(c) <
1447                     BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
1448                         return 0;
1449                 if (ret < 0)
1450                         return ret;
1451         }
1452
1453         c_nritems = btrfs_header_nritems(c);
1454         if (root->ref_cows)
1455                 root_gen = trans->transid;
1456         else
1457                 root_gen = 0;
1458
1459         btrfs_node_key(c, &disk_key, 0);
1460         split = __btrfs_alloc_free_block(trans, root, root->nodesize,
1461                                          root->root_key.objectid,
1462                                          root_gen,
1463                                          btrfs_disk_key_objectid(&disk_key),
1464                                          level, c->start, 0);
1465         if (IS_ERR(split))
1466                 return PTR_ERR(split);
1467
1468         btrfs_set_header_flags(split, btrfs_header_flags(c));
1469         btrfs_set_header_level(split, btrfs_header_level(c));
1470         btrfs_set_header_bytenr(split, split->start);
1471         btrfs_set_header_generation(split, trans->transid);
1472         btrfs_set_header_owner(split, root->root_key.objectid);
1473         btrfs_set_header_flags(split, 0);
1474         write_extent_buffer(split, root->fs_info->fsid,
1475                             (unsigned long)btrfs_header_fsid(split),
1476                             BTRFS_FSID_SIZE);
1477
1478         mid = (c_nritems + 1) / 2;
1479
1480         copy_extent_buffer(split, c,
1481                            btrfs_node_key_ptr_offset(0),
1482                            btrfs_node_key_ptr_offset(mid),
1483                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1484         btrfs_set_header_nritems(split, c_nritems - mid);
1485         btrfs_set_header_nritems(c, mid);
1486         ret = 0;
1487
1488         btrfs_mark_buffer_dirty(c);
1489         btrfs_mark_buffer_dirty(split);
1490
1491         btrfs_node_key(split, &disk_key, 0);
1492         wret = insert_ptr(trans, root, path, &disk_key, split->start,
1493                           path->slots[level + 1] + 1,
1494                           level + 1);
1495         if (wret)
1496                 ret = wret;
1497
1498         if (path->slots[level] >= mid) {
1499                 path->slots[level] -= mid;
1500                 free_extent_buffer(c);
1501                 path->nodes[level] = split;
1502                 path->slots[level + 1] += 1;
1503         } else {
1504                 free_extent_buffer(split);
1505         }
1506         return ret;
1507 }
1508
1509 /*
1510  * how many bytes are required to store the items in a leaf.  start
1511  * and nr indicate which items in the leaf to check.  This totals up the
1512  * space used both by the item structs and the item data
1513  */
1514 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1515 {
1516         int data_len;
1517         int nritems = btrfs_header_nritems(l);
1518         int end = min(nritems, start + nr) - 1;
1519
1520         if (!nr)
1521                 return 0;
1522         data_len = btrfs_item_end_nr(l, start);
1523         data_len = data_len - btrfs_item_offset_nr(l, end);
1524         data_len += sizeof(struct btrfs_item) * nr;
1525         WARN_ON(data_len < 0);
1526         return data_len;
1527 }
1528
1529 /*
1530  * The space between the end of the leaf items and
1531  * the start of the leaf data.  IOW, how much room
1532  * the leaf has left for both items and data
1533  */
1534 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1535 {
1536         int nritems = btrfs_header_nritems(leaf);
1537         int ret;
1538         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1539         if (ret < 0) {
1540                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1541                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
1542                        leaf_space_used(leaf, 0, nritems), nritems);
1543         }
1544         return ret;
1545 }
1546
1547 /*
1548  * push some data in the path leaf to the right, trying to free up at
1549  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1550  *
1551  * returns 1 if the push failed because the other node didn't have enough
1552  * room, 0 if everything worked out and < 0 if there were major errors.
1553  */
1554 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1555                            *root, struct btrfs_path *path, int data_size,
1556                            int empty)
1557 {
1558         struct extent_buffer *left = path->nodes[0];
1559         struct extent_buffer *right;
1560         struct extent_buffer *upper;
1561         struct btrfs_disk_key disk_key;
1562         int slot;
1563         u32 i;
1564         int free_space;
1565         int push_space = 0;
1566         int push_items = 0;
1567         struct btrfs_item *item;
1568         u32 left_nritems;
1569         u32 nr;
1570         u32 right_nritems;
1571         u32 data_end;
1572         u32 this_item_size;
1573         int ret;
1574
1575         slot = path->slots[1];
1576         if (!path->nodes[1]) {
1577                 return 1;
1578         }
1579         upper = path->nodes[1];
1580         if (slot >= btrfs_header_nritems(upper) - 1)
1581                 return 1;
1582
1583         right = read_tree_block(root, btrfs_node_blockptr(upper, slot + 1),
1584                                 root->leafsize);
1585         free_space = btrfs_leaf_free_space(root, right);
1586         if (free_space < data_size + sizeof(struct btrfs_item)) {
1587                 free_extent_buffer(right);
1588                 return 1;
1589         }
1590
1591         /* cow and double check */
1592         ret = btrfs_cow_block(trans, root, right, upper,
1593                               slot + 1, &right);
1594         if (ret) {
1595                 free_extent_buffer(right);
1596                 return 1;
1597         }
1598         free_space = btrfs_leaf_free_space(root, right);
1599         if (free_space < data_size + sizeof(struct btrfs_item)) {
1600                 free_extent_buffer(right);
1601                 return 1;
1602         }
1603
1604         left_nritems = btrfs_header_nritems(left);
1605         if (left_nritems == 0) {
1606                 free_extent_buffer(right);
1607                 return 1;
1608         }
1609
1610         if (empty)
1611                 nr = 0;
1612         else
1613                 nr = 1;
1614
1615         i = left_nritems - 1;
1616         while (i >= nr) {
1617                 item = btrfs_item_nr(left, i);
1618
1619                 if (path->slots[0] == i)
1620                         push_space += data_size + sizeof(*item);
1621
1622                 this_item_size = btrfs_item_size(left, item);
1623                 if (this_item_size + sizeof(*item) + push_space > free_space)
1624                         break;
1625                 push_items++;
1626                 push_space += this_item_size + sizeof(*item);
1627                 if (i == 0)
1628                         break;
1629                 i--;
1630         }
1631
1632         if (push_items == 0) {
1633                 free_extent_buffer(right);
1634                 return 1;
1635         }
1636
1637         if (!empty && push_items == left_nritems)
1638                 WARN_ON(1);
1639
1640         /* push left to right */
1641         right_nritems = btrfs_header_nritems(right);
1642
1643         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1644         push_space -= leaf_data_end(root, left);
1645
1646         /* make room in the right data area */
1647         data_end = leaf_data_end(root, right);
1648         memmove_extent_buffer(right,
1649                               btrfs_leaf_data(right) + data_end - push_space,
1650                               btrfs_leaf_data(right) + data_end,
1651                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1652
1653         /* copy from the left data area */
1654         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1655                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1656                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1657                      push_space);
1658
1659         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1660                               btrfs_item_nr_offset(0),
1661                               right_nritems * sizeof(struct btrfs_item));
1662
1663         /* copy the items from left to right */
1664         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1665                    btrfs_item_nr_offset(left_nritems - push_items),
1666                    push_items * sizeof(struct btrfs_item));
1667
1668         /* update the item pointers */
1669         right_nritems += push_items;
1670         btrfs_set_header_nritems(right, right_nritems);
1671         push_space = BTRFS_LEAF_DATA_SIZE(root);
1672         for (i = 0; i < right_nritems; i++) {
1673                 item = btrfs_item_nr(right, i);
1674                 push_space -= btrfs_item_size(right, item);
1675                 btrfs_set_item_offset(right, item, push_space);
1676         }
1677
1678         left_nritems -= push_items;
1679         btrfs_set_header_nritems(left, left_nritems);
1680
1681         if (left_nritems)
1682                 btrfs_mark_buffer_dirty(left);
1683         btrfs_mark_buffer_dirty(right);
1684
1685         btrfs_item_key(right, &disk_key, 0);
1686         btrfs_set_node_key(upper, &disk_key, slot + 1);
1687         btrfs_mark_buffer_dirty(upper);
1688
1689         /* then fixup the leaf pointer in the path */
1690         if (path->slots[0] >= left_nritems) {
1691                 path->slots[0] -= left_nritems;
1692                 free_extent_buffer(path->nodes[0]);
1693                 path->nodes[0] = right;
1694                 path->slots[1] += 1;
1695         } else {
1696                 free_extent_buffer(right);
1697         }
1698         return 0;
1699 }
1700 /*
1701  * push some data in the path leaf to the left, trying to free up at
1702  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1703  */
1704 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1705                           *root, struct btrfs_path *path, int data_size,
1706                           int empty)
1707 {
1708         struct btrfs_disk_key disk_key;
1709         struct extent_buffer *right = path->nodes[0];
1710         struct extent_buffer *left;
1711         int slot;
1712         int i;
1713         int free_space;
1714         int push_space = 0;
1715         int push_items = 0;
1716         struct btrfs_item *item;
1717         u32 old_left_nritems;
1718         u32 right_nritems;
1719         u32 nr;
1720         int ret = 0;
1721         int wret;
1722         u32 this_item_size;
1723         u32 old_left_item_size;
1724
1725         slot = path->slots[1];
1726         if (slot == 0)
1727                 return 1;
1728         if (!path->nodes[1])
1729                 return 1;
1730
1731         right_nritems = btrfs_header_nritems(right);
1732         if (right_nritems == 0) {
1733                 return 1;
1734         }
1735
1736         left = read_tree_block(root, btrfs_node_blockptr(path->nodes[1],
1737                                slot - 1), root->leafsize);
1738         free_space = btrfs_leaf_free_space(root, left);
1739         if (free_space < data_size + sizeof(struct btrfs_item)) {
1740                 free_extent_buffer(left);
1741                 return 1;
1742         }
1743
1744         /* cow and double check */
1745         ret = btrfs_cow_block(trans, root, left,
1746                               path->nodes[1], slot - 1, &left);
1747         if (ret) {
1748                 /* we hit -ENOSPC, but it isn't fatal here */
1749                 free_extent_buffer(left);
1750                 return 1;
1751         }
1752
1753         free_space = btrfs_leaf_free_space(root, left);
1754         if (free_space < data_size + sizeof(struct btrfs_item)) {
1755                 free_extent_buffer(left);
1756                 return 1;
1757         }
1758
1759         if (empty)
1760                 nr = right_nritems;
1761         else
1762                 nr = right_nritems - 1;
1763
1764         for (i = 0; i < nr; i++) {
1765                 item = btrfs_item_nr(right, i);
1766
1767                 if (path->slots[0] == i)
1768                         push_space += data_size + sizeof(*item);
1769
1770                 this_item_size = btrfs_item_size(right, item);
1771                 if (this_item_size + sizeof(*item) + push_space > free_space)
1772                         break;
1773
1774                 push_items++;
1775                 push_space += this_item_size + sizeof(*item);
1776         }
1777
1778         if (push_items == 0) {
1779                 free_extent_buffer(left);
1780                 return 1;
1781         }
1782         if (!empty && push_items == btrfs_header_nritems(right))
1783                 WARN_ON(1);
1784
1785         /* push data from right to left */
1786         copy_extent_buffer(left, right,
1787                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1788                            btrfs_item_nr_offset(0),
1789                            push_items * sizeof(struct btrfs_item));
1790
1791         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1792                      btrfs_item_offset_nr(right, push_items -1);
1793
1794         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1795                      leaf_data_end(root, left) - push_space,
1796                      btrfs_leaf_data(right) +
1797                      btrfs_item_offset_nr(right, push_items - 1),
1798                      push_space);
1799         old_left_nritems = btrfs_header_nritems(left);
1800         BUG_ON(old_left_nritems < 0);
1801
1802         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
1803         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1804                 u32 ioff;
1805
1806                 item = btrfs_item_nr(left, i);
1807                 ioff = btrfs_item_offset(left, item);
1808                 btrfs_set_item_offset(left, item,
1809                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
1810         }
1811         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1812
1813         /* fixup right node */
1814         if (push_items > right_nritems) {
1815                 printk("push items %d nr %u\n", push_items, right_nritems);
1816                 WARN_ON(1);
1817         }
1818
1819         if (push_items < right_nritems) {
1820                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
1821                                                   leaf_data_end(root, right);
1822                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
1823                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
1824                                       btrfs_leaf_data(right) +
1825                                       leaf_data_end(root, right), push_space);
1826
1827                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1828                               btrfs_item_nr_offset(push_items),
1829                              (btrfs_header_nritems(right) - push_items) *
1830                              sizeof(struct btrfs_item));
1831         }
1832         right_nritems -= push_items;
1833         btrfs_set_header_nritems(right, right_nritems);
1834         push_space = BTRFS_LEAF_DATA_SIZE(root);
1835         for (i = 0; i < right_nritems; i++) {
1836                 item = btrfs_item_nr(right, i);
1837                 push_space = push_space - btrfs_item_size(right, item);
1838                 btrfs_set_item_offset(right, item, push_space);
1839         }
1840
1841         btrfs_mark_buffer_dirty(left);
1842         if (right_nritems)
1843                 btrfs_mark_buffer_dirty(right);
1844
1845         btrfs_item_key(right, &disk_key, 0);
1846         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1847         if (wret)
1848                 ret = wret;
1849
1850         /* then fixup the leaf pointer in the path */
1851         if (path->slots[0] < push_items) {
1852                 path->slots[0] += old_left_nritems;
1853                 free_extent_buffer(path->nodes[0]);
1854                 path->nodes[0] = left;
1855                 path->slots[1] -= 1;
1856         } else {
1857                 free_extent_buffer(left);
1858                 path->slots[0] -= push_items;
1859         }
1860         BUG_ON(path->slots[0] < 0);
1861         return ret;
1862 }
1863
1864 /*
1865  * split the path's leaf in two, making sure there is at least data_size
1866  * available for the resulting leaf level of the path.
1867  *
1868  * returns 0 if all went well and < 0 on failure.
1869  */
1870 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1871                       *root, struct btrfs_key *ins_key,
1872                       struct btrfs_path *path, int data_size, int extend)
1873 {
1874         u64 root_gen;
1875         struct extent_buffer *l;
1876         u32 nritems;
1877         int mid;
1878         int slot;
1879         struct extent_buffer *right;
1880         int space_needed = data_size + sizeof(struct btrfs_item);
1881         int data_copy_size;
1882         int rt_data_off;
1883         int i;
1884         int ret = 0;
1885         int wret;
1886         int double_split;
1887         int num_doubles = 0;
1888         struct btrfs_disk_key disk_key;
1889
1890         if (extend)
1891                 space_needed = data_size;
1892
1893         if (root->ref_cows)
1894                 root_gen = trans->transid;
1895         else
1896                 root_gen = 0;
1897
1898         /* first try to make some room by pushing left and right */
1899         if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
1900                 wret = push_leaf_right(trans, root, path, data_size, 0);
1901                 if (wret < 0) {
1902                         return wret;
1903                 }
1904                 if (wret) {
1905                         wret = push_leaf_left(trans, root, path, data_size, 0);
1906                         if (wret < 0)
1907                                 return wret;
1908                 }
1909                 l = path->nodes[0];
1910
1911                 /* did the pushes work? */
1912                 if (btrfs_leaf_free_space(root, l) >= space_needed)
1913                         return 0;
1914         }
1915
1916         if (!path->nodes[1]) {
1917                 ret = insert_new_root(trans, root, path, 1);
1918                 if (ret)
1919                         return ret;
1920         }
1921 again:
1922         double_split = 0;
1923         l = path->nodes[0];
1924         slot = path->slots[0];
1925         nritems = btrfs_header_nritems(l);
1926         mid = (nritems + 1)/ 2;
1927
1928         btrfs_item_key(l, &disk_key, 0);
1929
1930         right = __btrfs_alloc_free_block(trans, root, root->leafsize,
1931                                          root->root_key.objectid,
1932                                          root_gen, disk_key.objectid, 0,
1933                                          l->start, 0);
1934         if (IS_ERR(right))
1935                 return PTR_ERR(right);
1936
1937         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1938         btrfs_set_header_bytenr(right, right->start);
1939         btrfs_set_header_generation(right, trans->transid);
1940         btrfs_set_header_owner(right, root->root_key.objectid);
1941         btrfs_set_header_level(right, 0);
1942         write_extent_buffer(right, root->fs_info->fsid,
1943                             (unsigned long)btrfs_header_fsid(right),
1944                             BTRFS_FSID_SIZE);
1945         if (mid <= slot) {
1946                 if (nritems == 1 ||
1947                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1948                         BTRFS_LEAF_DATA_SIZE(root)) {
1949                         if (slot >= nritems) {
1950                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1951                                 btrfs_set_header_nritems(right, 0);
1952                                 wret = insert_ptr(trans, root, path,
1953                                                   &disk_key, right->start,
1954                                                   path->slots[1] + 1, 1);
1955                                 if (wret)
1956                                         ret = wret;
1957                                 free_extent_buffer(path->nodes[0]);
1958                                 path->nodes[0] = right;
1959                                 path->slots[0] = 0;
1960                                 path->slots[1] += 1;
1961                                 return ret;
1962                         }
1963                         mid = slot;
1964                         if (mid != nritems &&
1965                             leaf_space_used(l, mid, nritems - mid) +
1966                             space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1967                                 double_split = 1;
1968                         }
1969                 }
1970         } else {
1971                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1972                         BTRFS_LEAF_DATA_SIZE(root)) {
1973                         if (!extend && slot == 0) {
1974                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1975                                 btrfs_set_header_nritems(right, 0);
1976                                 wret = insert_ptr(trans, root, path,
1977                                                   &disk_key,
1978                                                   right->start,
1979                                                   path->slots[1], 1);
1980                                 if (wret)
1981                                         ret = wret;
1982                                 free_extent_buffer(path->nodes[0]);
1983                                 path->nodes[0] = right;
1984                                 path->slots[0] = 0;
1985                                 if (path->slots[1] == 0) {
1986                                         wret = fixup_low_keys(trans, root,
1987                                                    path, &disk_key, 1);
1988                                         if (wret)
1989                                                 ret = wret;
1990                                 }
1991                                 return ret;
1992                         } else if (extend && slot == 0) {
1993                                 mid = 1;
1994                         } else {
1995                                 mid = slot;
1996                                 if (mid != nritems &&
1997                                     leaf_space_used(l, mid, nritems - mid) +
1998                                     space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1999                                         double_split = 1;
2000                                 }
2001                         }
2002                 }
2003         }
2004         nritems = nritems - mid;
2005         btrfs_set_header_nritems(right, nritems);
2006         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
2007
2008         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2009                            btrfs_item_nr_offset(mid),
2010                            nritems * sizeof(struct btrfs_item));
2011
2012         copy_extent_buffer(right, l,
2013                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2014                      data_copy_size, btrfs_leaf_data(l) +
2015                      leaf_data_end(root, l), data_copy_size);
2016
2017         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2018                       btrfs_item_end_nr(l, mid);
2019
2020         for (i = 0; i < nritems; i++) {
2021                 struct btrfs_item *item = btrfs_item_nr(right, i);
2022                 u32 ioff = btrfs_item_offset(right, item);
2023                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2024         }
2025
2026         btrfs_set_header_nritems(l, mid);
2027         ret = 0;
2028         btrfs_item_key(right, &disk_key, 0);
2029         wret = insert_ptr(trans, root, path, &disk_key, right->start,
2030                           path->slots[1] + 1, 1);
2031         if (wret)
2032                 ret = wret;
2033
2034         btrfs_mark_buffer_dirty(right);
2035         btrfs_mark_buffer_dirty(l);
2036         BUG_ON(path->slots[0] != slot);
2037
2038         if (mid <= slot) {
2039                 free_extent_buffer(path->nodes[0]);
2040                 path->nodes[0] = right;
2041                 path->slots[0] -= mid;
2042                 path->slots[1] += 1;
2043         } else
2044                 free_extent_buffer(right);
2045
2046         BUG_ON(path->slots[0] < 0);
2047
2048         if (double_split) {
2049                 BUG_ON(num_doubles != 0);
2050                 num_doubles++;
2051                 goto again;
2052         }
2053         return ret;
2054 }
2055
2056 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
2057                         struct btrfs_root *root,
2058                         struct btrfs_path *path,
2059                         u32 new_size, int from_end)
2060 {
2061         int ret = 0;
2062         int slot;
2063         int slot_orig;
2064         struct extent_buffer *leaf;
2065         struct btrfs_item *item;
2066         u32 nritems;
2067         unsigned int data_end;
2068         unsigned int old_data_start;
2069         unsigned int old_size;
2070         unsigned int size_diff;
2071         int i;
2072
2073         slot_orig = path->slots[0];
2074         leaf = path->nodes[0];
2075         slot = path->slots[0];
2076
2077         old_size = btrfs_item_size_nr(leaf, slot);
2078         if (old_size == new_size)
2079                 return 0;
2080
2081         nritems = btrfs_header_nritems(leaf);
2082         data_end = leaf_data_end(root, leaf);
2083
2084         old_data_start = btrfs_item_offset_nr(leaf, slot);
2085
2086         size_diff = old_size - new_size;
2087
2088         BUG_ON(slot < 0);
2089         BUG_ON(slot >= nritems);
2090
2091         /*
2092          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2093          */
2094         /* first correct the data pointers */
2095         for (i = slot; i < nritems; i++) {
2096                 u32 ioff;
2097                 item = btrfs_item_nr(leaf, i);
2098                 ioff = btrfs_item_offset(leaf, item);
2099                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2100         }
2101
2102         /* shift the data */
2103         if (from_end) {
2104                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2105                               data_end + size_diff, btrfs_leaf_data(leaf) +
2106                               data_end, old_data_start + new_size - data_end);
2107         } else {
2108                 struct btrfs_disk_key disk_key;
2109                 u64 offset;
2110
2111                 btrfs_item_key(leaf, &disk_key, slot);
2112
2113                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
2114                         unsigned long ptr;
2115                         struct btrfs_file_extent_item *fi;
2116
2117                         fi = btrfs_item_ptr(leaf, slot,
2118                                             struct btrfs_file_extent_item);
2119                         fi = (struct btrfs_file_extent_item *)(
2120                              (unsigned long)fi - size_diff);
2121
2122                         if (btrfs_file_extent_type(leaf, fi) ==
2123                             BTRFS_FILE_EXTENT_INLINE) {
2124                                 ptr = btrfs_item_ptr_offset(leaf, slot);
2125                                 memmove_extent_buffer(leaf, ptr,
2126                                         (unsigned long)fi,
2127                                         offsetof(struct btrfs_file_extent_item,
2128                                                  disk_bytenr));
2129                         }
2130                 }
2131
2132                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2133                               data_end + size_diff, btrfs_leaf_data(leaf) +
2134                               data_end, old_data_start - data_end);
2135
2136                 offset = btrfs_disk_key_offset(&disk_key);
2137                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
2138                 btrfs_set_item_key(leaf, &disk_key, slot);
2139                 if (slot == 0)
2140                         fixup_low_keys(trans, root, path, &disk_key, 1);
2141         }
2142
2143         item = btrfs_item_nr(leaf, slot);
2144         btrfs_set_item_size(leaf, item, new_size);
2145         btrfs_mark_buffer_dirty(leaf);
2146
2147         ret = 0;
2148         if (btrfs_leaf_free_space(root, leaf) < 0) {
2149                 btrfs_print_leaf(root, leaf);
2150                 BUG();
2151         }
2152         return ret;
2153 }
2154
2155 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2156                       struct btrfs_root *root, struct btrfs_path *path,
2157                       u32 data_size)
2158 {
2159         int ret = 0;
2160         int slot;
2161         int slot_orig;
2162         struct extent_buffer *leaf;
2163         struct btrfs_item *item;
2164         u32 nritems;
2165         unsigned int data_end;
2166         unsigned int old_data;
2167         unsigned int old_size;
2168         int i;
2169
2170         slot_orig = path->slots[0];
2171         leaf = path->nodes[0];
2172
2173         nritems = btrfs_header_nritems(leaf);
2174         data_end = leaf_data_end(root, leaf);
2175
2176         if (btrfs_leaf_free_space(root, leaf) < data_size) {
2177                 btrfs_print_leaf(root, leaf);
2178                 BUG();
2179         }
2180         slot = path->slots[0];
2181         old_data = btrfs_item_end_nr(leaf, slot);
2182
2183         BUG_ON(slot < 0);
2184         if (slot >= nritems) {
2185                 btrfs_print_leaf(root, leaf);
2186                 printk("slot %d too large, nritems %d\n", slot, nritems);
2187                 BUG_ON(1);
2188         }
2189
2190         /*
2191          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2192          */
2193         /* first correct the data pointers */
2194         for (i = slot; i < nritems; i++) {
2195                 u32 ioff;
2196                 item = btrfs_item_nr(leaf, i);
2197                 ioff = btrfs_item_offset(leaf, item);
2198                 btrfs_set_item_offset(leaf, item, ioff - data_size);
2199         }
2200
2201         /* shift the data */
2202         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2203                       data_end - data_size, btrfs_leaf_data(leaf) +
2204                       data_end, old_data - data_end);
2205
2206         data_end = old_data;
2207         old_size = btrfs_item_size_nr(leaf, slot);
2208         item = btrfs_item_nr(leaf, slot);
2209         btrfs_set_item_size(leaf, item, old_size + data_size);
2210         btrfs_mark_buffer_dirty(leaf);
2211
2212         ret = 0;
2213         if (btrfs_leaf_free_space(root, leaf) < 0) {
2214                 btrfs_print_leaf(root, leaf);
2215                 BUG();
2216         }
2217         return ret;
2218 }
2219
2220 /*
2221  * Given a key and some data, insert an item into the tree.
2222  * This does all the path init required, making room in the tree if needed.
2223  */
2224 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
2225                             struct btrfs_root *root,
2226                             struct btrfs_path *path,
2227                             struct btrfs_key *cpu_key, u32 *data_size,
2228                             int nr)
2229 {
2230         struct extent_buffer *leaf;
2231         struct btrfs_item *item;
2232         int ret = 0;
2233         int slot;
2234         int slot_orig;
2235         int i;
2236         u32 nritems;
2237         u32 total_size = 0;
2238         u32 total_data = 0;
2239         unsigned int data_end;
2240         struct btrfs_disk_key disk_key;
2241
2242         for (i = 0; i < nr; i++) {
2243                 total_data += data_size[i];
2244         }
2245
2246         /* create a root if there isn't one */
2247         if (!root->node)
2248                 BUG();
2249
2250         total_size = total_data + (nr - 1) * sizeof(struct btrfs_item);
2251         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
2252         if (ret == 0) {
2253                 return -EEXIST;
2254         }
2255         if (ret < 0)
2256                 goto out;
2257
2258         slot_orig = path->slots[0];
2259         leaf = path->nodes[0];
2260
2261         nritems = btrfs_header_nritems(leaf);
2262         data_end = leaf_data_end(root, leaf);
2263
2264         if (btrfs_leaf_free_space(root, leaf) <
2265             sizeof(struct btrfs_item) + total_size) {
2266                 btrfs_print_leaf(root, leaf);
2267                 printk("not enough freespace need %u have %d\n",
2268                        total_size, btrfs_leaf_free_space(root, leaf));
2269                 BUG();
2270         }
2271
2272         slot = path->slots[0];
2273         BUG_ON(slot < 0);
2274
2275         if (slot != nritems) {
2276                 int i;
2277                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2278
2279                 if (old_data < data_end) {
2280                         btrfs_print_leaf(root, leaf);
2281                         printk("slot %d old_data %d data_end %d\n",
2282                                slot, old_data, data_end);
2283                         BUG_ON(1);
2284                 }
2285                 /*
2286                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2287                  */
2288                 /* first correct the data pointers */
2289                 for (i = slot; i < nritems; i++) {
2290                         u32 ioff;
2291
2292                         item = btrfs_item_nr(leaf, i);
2293                         ioff = btrfs_item_offset(leaf, item);
2294                         btrfs_set_item_offset(leaf, item, ioff - total_data);
2295                 }
2296
2297                 /* shift the items */
2298                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
2299                               btrfs_item_nr_offset(slot),
2300                               (nritems - slot) * sizeof(struct btrfs_item));
2301
2302                 /* shift the data */
2303                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2304                               data_end - total_data, btrfs_leaf_data(leaf) +
2305                               data_end, old_data - data_end);
2306                 data_end = old_data;
2307         }
2308
2309         /* setup the item for the new data */
2310         for (i = 0; i < nr; i++) {
2311                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
2312                 btrfs_set_item_key(leaf, &disk_key, slot + i);
2313                 item = btrfs_item_nr(leaf, slot + i);
2314                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
2315                 data_end -= data_size[i];
2316                 btrfs_set_item_size(leaf, item, data_size[i]);
2317         }
2318         btrfs_set_header_nritems(leaf, nritems + nr);
2319         btrfs_mark_buffer_dirty(leaf);
2320
2321         ret = 0;
2322         if (slot == 0) {
2323                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2324                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2325         }
2326
2327         if (btrfs_leaf_free_space(root, leaf) < 0) {
2328                 btrfs_print_leaf(root, leaf);
2329                 BUG();
2330         }
2331
2332 out:
2333         return ret;
2334 }
2335
2336 /*
2337  * Given a key and some data, insert an item into the tree.
2338  * This does all the path init required, making room in the tree if needed.
2339  */
2340 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2341                       *root, struct btrfs_key *cpu_key, void *data, u32
2342                       data_size)
2343 {
2344         int ret = 0;
2345         struct btrfs_path *path;
2346         struct extent_buffer *leaf;
2347         unsigned long ptr;
2348
2349         path = btrfs_alloc_path();
2350         BUG_ON(!path);
2351         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2352         if (!ret) {
2353                 leaf = path->nodes[0];
2354                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2355                 write_extent_buffer(leaf, data, ptr, data_size);
2356                 btrfs_mark_buffer_dirty(leaf);
2357         }
2358         btrfs_free_path(path);
2359         return ret;
2360 }
2361
2362 /*
2363  * delete the pointer from a given node.
2364  *
2365  * If the delete empties a node, the node is removed from the tree,
2366  * continuing all the way the root if required.  The root is converted into
2367  * a leaf if all the nodes are emptied.
2368  */
2369 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2370                    struct btrfs_path *path, int level, int slot)
2371 {
2372         struct extent_buffer *parent = path->nodes[level];
2373         u32 nritems;
2374         int ret = 0;
2375         int wret;
2376
2377         nritems = btrfs_header_nritems(parent);
2378         if (slot != nritems -1) {
2379                 memmove_extent_buffer(parent,
2380                               btrfs_node_key_ptr_offset(slot),
2381                               btrfs_node_key_ptr_offset(slot + 1),
2382                               sizeof(struct btrfs_key_ptr) *
2383                               (nritems - slot - 1));
2384         }
2385         nritems--;
2386         btrfs_set_header_nritems(parent, nritems);
2387         if (nritems == 0 && parent == root->node) {
2388                 BUG_ON(btrfs_header_level(root->node) != 1);
2389                 /* just turn the root into a leaf and break */
2390                 btrfs_set_header_level(root->node, 0);
2391         } else if (slot == 0) {
2392                 struct btrfs_disk_key disk_key;
2393
2394                 btrfs_node_key(parent, &disk_key, 0);
2395                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2396                 if (wret)
2397                         ret = wret;
2398         }
2399         btrfs_mark_buffer_dirty(parent);
2400         return ret;
2401 }
2402
2403 /*
2404  * delete the item at the leaf level in path.  If that empties
2405  * the leaf, remove it from the tree
2406  */
2407 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2408                     struct btrfs_path *path, int slot, int nr)
2409 {
2410         struct extent_buffer *leaf;
2411         struct btrfs_item *item;
2412         int last_off;
2413         int dsize = 0;
2414         int ret = 0;
2415         int wret;
2416         int i;
2417         u32 nritems;
2418
2419         leaf = path->nodes[0];
2420         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
2421
2422         for (i = 0; i < nr; i++)
2423                 dsize += btrfs_item_size_nr(leaf, slot + i);
2424
2425         nritems = btrfs_header_nritems(leaf);
2426
2427         if (slot + nr != nritems) {
2428                 int i;
2429                 int data_end = leaf_data_end(root, leaf);
2430
2431                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2432                               data_end + dsize,
2433                               btrfs_leaf_data(leaf) + data_end,
2434                               last_off - data_end);
2435
2436                 for (i = slot + nr; i < nritems; i++) {
2437                         u32 ioff;
2438
2439                         item = btrfs_item_nr(leaf, i);
2440                         ioff = btrfs_item_offset(leaf, item);
2441                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2442                 }
2443
2444                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2445                               btrfs_item_nr_offset(slot + nr),
2446                               sizeof(struct btrfs_item) *
2447                               (nritems - slot - nr));
2448         }
2449         btrfs_set_header_nritems(leaf, nritems - nr);
2450         nritems -= nr;
2451
2452         /* delete the leaf if we've emptied it */
2453         if (nritems == 0) {
2454                 if (leaf == root->node) {
2455                         btrfs_set_header_level(leaf, 0);
2456                 } else {
2457                         u64 root_gen = btrfs_header_generation(path->nodes[1]);
2458                         clean_tree_block(trans, root, leaf);
2459                         wait_on_tree_block_writeback(root, leaf);
2460                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
2461                         if (wret)
2462                                 ret = wret;
2463                         wret = btrfs_free_extent(trans, root,
2464                                          leaf->start, leaf->len,
2465                                          btrfs_header_owner(path->nodes[1]),
2466                                          root_gen, 0, 0, 1);
2467                         if (wret)
2468                                 ret = wret;
2469                 }
2470         } else {
2471                 int used = leaf_space_used(leaf, 0, nritems);
2472                 if (slot == 0) {
2473                         struct btrfs_disk_key disk_key;
2474
2475                         btrfs_item_key(leaf, &disk_key, 0);
2476                         wret = fixup_low_keys(trans, root, path,
2477                                               &disk_key, 1);
2478                         if (wret)
2479                                 ret = wret;
2480                 }
2481
2482                 /* delete the leaf if it is mostly empty */
2483                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 4) {
2484                         /* push_leaf_left fixes the path.
2485                          * make sure the path still points to our leaf
2486                          * for possible call to del_ptr below
2487                          */
2488                         slot = path->slots[1];
2489                         extent_buffer_get(leaf);
2490
2491                         wret = push_leaf_left(trans, root, path, 1, 1);
2492                         if (wret < 0 && wret != -ENOSPC)
2493                                 ret = wret;
2494
2495                         if (path->nodes[0] == leaf &&
2496                             btrfs_header_nritems(leaf)) {
2497                                 wret = push_leaf_right(trans, root, path, 1, 1);
2498                                 if (wret < 0 && wret != -ENOSPC)
2499                                         ret = wret;
2500                         }
2501
2502                         if (btrfs_header_nritems(leaf) == 0) {
2503                                 u64 root_gen;
2504                                 u64 bytenr = leaf->start;
2505                                 u32 blocksize = leaf->len;
2506
2507                                 root_gen = btrfs_header_generation(
2508                                                            path->nodes[1]);
2509
2510                                 clean_tree_block(trans, root, leaf);
2511                                 wait_on_tree_block_writeback(root, leaf);
2512
2513                                 wret = del_ptr(trans, root, path, 1, slot);
2514                                 if (wret)
2515                                         ret = wret;
2516
2517                                 free_extent_buffer(leaf);
2518                                 wret = btrfs_free_extent(trans, root, bytenr,
2519                                              blocksize,
2520                                              btrfs_header_owner(path->nodes[1]),
2521                                              root_gen, 0, 0, 1);
2522                                 if (wret)
2523                                         ret = wret;
2524                         } else {
2525                                 btrfs_mark_buffer_dirty(leaf);
2526                                 free_extent_buffer(leaf);
2527                         }
2528                 } else {
2529                         btrfs_mark_buffer_dirty(leaf);
2530                 }
2531         }
2532         return ret;
2533 }
2534
2535 /*
2536  * walk up the tree as far as required to find the previous leaf.
2537  * returns 0 if it found something or 1 if there are no lesser leaves.
2538  * returns < 0 on io errors.
2539  */
2540 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2541 {
2542         u64 bytenr;
2543         int slot;
2544         int level = 1;
2545         struct extent_buffer *c;
2546         struct extent_buffer *next = NULL;
2547
2548         while(level < BTRFS_MAX_LEVEL) {
2549                 if (!path->nodes[level])
2550                         return 1;
2551
2552                 slot = path->slots[level];
2553                 c = path->nodes[level];
2554                 if (slot == 0) {
2555                         level++;
2556                         if (level == BTRFS_MAX_LEVEL)
2557                                 return 1;
2558                         continue;
2559                 }
2560                 slot--;
2561
2562                 bytenr = btrfs_node_blockptr(c, slot);
2563                 if (next)
2564                         free_extent_buffer(next);
2565
2566                 next = read_tree_block(root, bytenr,
2567                                        btrfs_level_size(root, level - 1));
2568                 break;
2569         }
2570         path->slots[level] = slot;
2571         while(1) {
2572                 level--;
2573                 c = path->nodes[level];
2574                 free_extent_buffer(c);
2575                 slot = btrfs_header_nritems(next);
2576                 if (slot != 0)
2577                         slot--;
2578                 path->nodes[level] = next;
2579                 path->slots[level] = slot;
2580                 if (!level)
2581                         break;
2582                 next = read_tree_block(root, btrfs_node_blockptr(next, slot),
2583                                        btrfs_level_size(root, level - 1));
2584         }
2585         return 0;
2586 }
2587
2588 /*
2589  * walk up the tree as far as required to find the next leaf.
2590  * returns 0 if it found something or 1 if there are no greater leaves.
2591  * returns < 0 on io errors.
2592  */
2593 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2594 {
2595         int slot;
2596         int level = 1;
2597         u64 bytenr;
2598         struct extent_buffer *c;
2599         struct extent_buffer *next = NULL;
2600
2601         while(level < BTRFS_MAX_LEVEL) {
2602                 if (!path->nodes[level])
2603                         return 1;
2604
2605                 slot = path->slots[level] + 1;
2606                 c = path->nodes[level];
2607                 if (slot >= btrfs_header_nritems(c)) {
2608                         level++;
2609                         if (level == BTRFS_MAX_LEVEL)
2610                                 return 1;
2611                         continue;
2612                 }
2613
2614                 bytenr = btrfs_node_blockptr(c, slot);
2615                 if (next)
2616                         free_extent_buffer(next);
2617
2618                 if (path->reada)
2619                         reada_for_search(root, path, level, slot, 0);
2620
2621                 next = read_tree_block(root, bytenr,
2622                                        btrfs_level_size(root, level -1));
2623                 break;
2624         }
2625         path->slots[level] = slot;
2626         while(1) {
2627                 level--;
2628                 c = path->nodes[level];
2629                 free_extent_buffer(c);
2630                 path->nodes[level] = next;
2631                 path->slots[level] = 0;
2632                 if (!level)
2633                         break;
2634                 if (path->reada)
2635                         reada_for_search(root, path, level, 0, 0);
2636                 next = read_tree_block(root, btrfs_node_blockptr(next, 0),
2637                                        btrfs_level_size(root, level - 1));
2638         }
2639         return 0;
2640 }
2641
2642 int btrfs_previous_item(struct btrfs_root *root,
2643                         struct btrfs_path *path, u64 min_objectid,
2644                         int type)
2645 {
2646         struct btrfs_key found_key;
2647         struct extent_buffer *leaf;
2648         int ret;
2649
2650         while(1) {
2651                 if (path->slots[0] == 0) {
2652                         ret = btrfs_prev_leaf(root, path);
2653                         if (ret != 0)
2654                                 return ret;
2655                 } else {
2656                         path->slots[0]--;
2657                 }
2658                 leaf = path->nodes[0];
2659                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2660                 if (found_key.type == type)
2661                         return 0;
2662         }
2663         return 1;
2664 }
2665