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, int empty);
  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             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
 249                 *cow_ret = buf;
 250                 return 0;
 251         }
 252
 253         search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
 254         ret = __btrfs_cow_block(trans, root, buf, parent,
 255                                  parent_slot, cow_ret, search_start, 0);
 256         return ret;
 257 }
 258
 259 /*
 260 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 261 {
 262         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 263                 return 1;
 264         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 265                 return 1;
 266         return 0;
 267 }
 268 */
 269
 270 /*
 271  * compare two keys in a memcmp fashion
 272  */
 273 int btrfs_comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 274 {
 275         struct btrfs_key k1;
 276
 277         btrfs_disk_key_to_cpu(&k1, disk);
 278
 279         if (k1.objectid > k2->objectid)
 280                 return 1;
 281         if (k1.objectid < k2->objectid)
 282                 return -1;
 283         if (k1.type > k2->type)
 284                 return 1;
 285         if (k1.type < k2->type)
 286                 return -1;
 287         if (k1.offset > k2->offset)
 288                 return 1;
 289         if (k1.offset < k2->offset)
 290                 return -1;
 291         return 0;
 292 }
 293
 294
 295 #if 0
 296 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 297                        struct btrfs_root *root, struct extent_buffer *parent,
 298                        int start_slot, int cache_only, u64 *last_ret,
 299                        struct btrfs_key *progress)
 300 {
 301         struct extent_buffer *cur;
 302         struct extent_buffer *tmp;
 303         u64 blocknr;
 304         u64 search_start = *last_ret;
 305         u64 last_block = 0;
 306         u64 other;
 307         u32 parent_nritems;
 308         int end_slot;
 309         int i;
 310         int err = 0;
 311         int parent_level;
 312         int uptodate;
 313         u32 blocksize;
 314         int progress_passed = 0;
 315         struct btrfs_disk_key disk_key;
 316
 317         parent_level = btrfs_header_level(parent);
 318         if (cache_only && parent_level != 1)
 319                 return 0;
 320
 321         if (trans->transaction != root->fs_info->running_transaction) {
 322                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 323                        root->fs_info->running_transaction->transid);
 324                 WARN_ON(1);
 325         }
 326         if (trans->transid != root->fs_info->generation) {
 327                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 328                        root->fs_info->generation);
 329                 WARN_ON(1);
 330         }
 331
 332         parent_nritems = btrfs_header_nritems(parent);
 333         blocksize = btrfs_level_size(root, parent_level - 1);
 334         end_slot = parent_nritems;
 335
 336         if (parent_nritems == 1)
 337                 return 0;
 338
 339         for (i = start_slot; i < end_slot; i++) {
 340                 int close = 1;
 341
 342                 if (!parent->map_token) {
 343                         map_extent_buffer(parent,
 344                                         btrfs_node_key_ptr_offset(i),
 345                                         sizeof(struct btrfs_key_ptr),
 346                                         &parent->map_token, &parent->kaddr,
 347                                         &parent->map_start, &parent->map_len,
 348                                         KM_USER1);
 349                 }
 350                 btrfs_node_key(parent, &disk_key, i);
 351                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
 352                         continue;
 353
 354                 progress_passed = 1;
 355                 blocknr = btrfs_node_blockptr(parent, i);
 356                 if (last_block == 0)
 357                         last_block = blocknr;
 358
 359                 if (i > 0) {
 360                         other = btrfs_node_blockptr(parent, i - 1);
 361                         close = close_blocks(blocknr, other, blocksize);
 362                 }
 363                 if (close && i < end_slot - 2) {
 364                         other = btrfs_node_blockptr(parent, i + 1);
 365                         close = close_blocks(blocknr, other, blocksize);
 366                 }
 367                 if (close) {
 368                         last_block = blocknr;
 369                         continue;
 370                 }
 371                 if (parent->map_token) {
 372                         unmap_extent_buffer(parent, parent->map_token,
 373                                             KM_USER1);
 374                         parent->map_token = NULL;
 375                 }
 376
 377                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
 378                 if (cur)
 379                         uptodate = btrfs_buffer_uptodate(cur);
 380                 else
 381                         uptodate = 0;
 382                 if (!cur || !uptodate) {
 383                         if (cache_only) {
 384                                 free_extent_buffer(cur);
 385                                 continue;
 386                         }
 387                         if (!cur) {
 388                                 cur = read_tree_block(root, blocknr,
 389                                                          blocksize);
 390                         } else if (!uptodate) {
 391                                 btrfs_read_buffer(cur);
 392                         }
 393                 }
 394                 if (search_start == 0)
 395                         search_start = last_block;
 396
 397                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 398                                         &tmp, search_start,
 399                                         min(16 * blocksize,
 400                                             (end_slot - i) * blocksize));
 401                 if (err) {
 402                         free_extent_buffer(cur);
 403                         break;
 404                 }
 405                 search_start = tmp->start;
 406                 last_block = tmp->start;
 407                 *last_ret = search_start;
 408                 if (parent_level == 1)
 409                         btrfs_clear_buffer_defrag(tmp);
 410                 free_extent_buffer(tmp);
 411         }
 412         if (parent->map_token) {
 413                 unmap_extent_buffer(parent, parent->map_token,
 414                                     KM_USER1);
 415                 parent->map_token = NULL;
 416         }
 417         return err;
 418 }
 419 #endif
 420
 421 /*
 422  * The leaf data grows from end-to-front in the node.
 423  * this returns the address of the start of the last item,
 424  * which is the stop of the leaf data stack
 425  */
 426 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 427                                          struct extent_buffer *leaf)
 428 {
 429         u32 nr = btrfs_header_nritems(leaf);
 430         if (nr == 0)
 431                 return BTRFS_LEAF_DATA_SIZE(root);
 432         return btrfs_item_offset_nr(leaf, nr - 1);
 433 }
 434
 435 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 436                       int level)
 437 {
 438         struct extent_buffer *parent = NULL;
 439         struct extent_buffer *node = path->nodes[level];
 440         struct btrfs_disk_key parent_key;
 441         struct btrfs_disk_key node_key;
 442         int parent_slot;
 443         int slot;
 444         struct btrfs_key cpukey;
 445         u32 nritems = btrfs_header_nritems(node);
 446
 447         if (path->nodes[level + 1])
 448                 parent = path->nodes[level + 1];
 449
 450         slot = path->slots[level];
 451         BUG_ON(nritems == 0);
 452         if (parent) {
 453                 parent_slot = path->slots[level + 1];
 454                 btrfs_node_key(parent, &parent_key, parent_slot);
 455                 btrfs_node_key(node, &node_key, 0);
 456                 BUG_ON(memcmp(&parent_key, &node_key,
 457                               sizeof(struct btrfs_disk_key)));
 458                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 459                        btrfs_header_bytenr(node));
 460         }
 461         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 462         if (slot != 0) {
 463                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 464                 btrfs_node_key(node, &node_key, slot);
 465                 BUG_ON(btrfs_comp_keys(&node_key, &cpukey) <= 0);
 466         }
 467         if (slot < nritems - 1) {
 468                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 469                 btrfs_node_key(node, &node_key, slot);
 470                 BUG_ON(btrfs_comp_keys(&node_key, &cpukey) >= 0);
 471         }
 472         return 0;
 473 }
 474
 475 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 476                       int level)
 477 {
 478         struct extent_buffer *leaf = path->nodes[level];
 479         struct extent_buffer *parent = NULL;
 480         int parent_slot;
 481         struct btrfs_key cpukey;
 482         struct btrfs_disk_key parent_key;
 483         struct btrfs_disk_key leaf_key;
 484         int slot = path->slots[0];
 485
 486         u32 nritems = btrfs_header_nritems(leaf);
 487
 488         if (path->nodes[level + 1])
 489                 parent = path->nodes[level + 1];
 490
 491         if (nritems == 0)
 492                 return 0;
 493
 494         if (parent) {
 495                 parent_slot = path->slots[level + 1];
 496                 btrfs_node_key(parent, &parent_key, parent_slot);
 497                 btrfs_item_key(leaf, &leaf_key, 0);
 498
 499                 BUG_ON(memcmp(&parent_key, &leaf_key,
 500                        sizeof(struct btrfs_disk_key)));
 501                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 502                        btrfs_header_bytenr(leaf));
 503         }
 504 #if 0
 505         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 506                 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
 507                 btrfs_item_key(leaf, &leaf_key, i);
 508                 if (comp_keys(&leaf_key, &cpukey) >= 0) {
 509                         btrfs_print_leaf(root, leaf);
 510                         printk("slot %d offset bad key\n", i);
 511                         BUG_ON(1);
 512                 }
 513                 if (btrfs_item_offset_nr(leaf, i) !=
 514                         btrfs_item_end_nr(leaf, i + 1)) {
 515                         btrfs_print_leaf(root, leaf);
 516                         printk("slot %d offset bad\n", i);
 517                         BUG_ON(1);
 518                 }
 519                 if (i == 0) {
 520                         if (btrfs_item_offset_nr(leaf, i) +
 521                                btrfs_item_size_nr(leaf, i) !=
 522                                BTRFS_LEAF_DATA_SIZE(root)) {
 523                                 btrfs_print_leaf(root, leaf);
 524                                 printk("slot %d first offset bad\n", i);
 525                                 BUG_ON(1);
 526                         }
 527                 }
 528         }
 529         if (nritems > 0) {
 530                 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
 531                                 btrfs_print_leaf(root, leaf);
 532                                 printk("slot %d bad size \n", nritems - 1);
 533                                 BUG_ON(1);
 534                 }
 535         }
 536 #endif
 537         if (slot != 0 && slot < nritems - 1) {
 538                 btrfs_item_key(leaf, &leaf_key, slot);
 539                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 540                 if (btrfs_comp_keys(&leaf_key, &cpukey) <= 0) {
 541                         btrfs_print_leaf(root, leaf);
 542                         printk("slot %d offset bad key\n", slot);
 543                         BUG_ON(1);
 544                 }
 545                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 546                        btrfs_item_end_nr(leaf, slot)) {
 547                         btrfs_print_leaf(root, leaf);
 548                         printk("slot %d offset bad\n", slot);
 549                         BUG_ON(1);
 550                 }
 551         }
 552         if (slot < nritems - 1) {
 553                 btrfs_item_key(leaf, &leaf_key, slot);
 554                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 555                 BUG_ON(btrfs_comp_keys(&leaf_key, &cpukey) >= 0);
 556                 if (btrfs_item_offset_nr(leaf, slot) !=
 557                         btrfs_item_end_nr(leaf, slot + 1)) {
 558                         btrfs_print_leaf(root, leaf);
 559                         printk("slot %d offset bad\n", slot);
 560                         BUG_ON(1);
 561                 }
 562         }
 563         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 564                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 565         return 0;
 566 }
 567
 568 static int noinline check_block(struct btrfs_root *root,
 569                                 struct btrfs_path *path, int level)
 570 {
 571         return 0;
 572 #if 0
 573         struct extent_buffer *buf = path->nodes[level];
 574
 575         if (memcmp_extent_buffer(buf, root->fs_info->fsid,
 576                                  (unsigned long)btrfs_header_fsid(buf),
 577                                  BTRFS_FSID_SIZE)) {
 578                 printk("warning bad block %Lu\n", buf->start);
 579                 return 1;
 580         }
 581 #endif
 582         if (level == 0)
 583                 return check_leaf(root, path, level);
 584         return check_node(root, path, level);
 585 }
 586
 587 /*
 588  * search for key in the extent_buffer.  The items start at offset p,
 589  * and they are item_size apart.  There are 'max' items in p.
 590  *
 591  * the slot in the array is returned via slot, and it points to
 592  * the place where you would insert key if it is not found in
 593  * the array.
 594  *
 595  * slot may point to max if the key is bigger than all of the keys
 596  */
 597 static int generic_bin_search(struct extent_buffer *eb, unsigned long p,
 598                               int item_size, struct btrfs_key *key,
 599                               int max, int *slot)
 600 {
 601         int low = 0;
 602         int high = max;
 603         int mid;
 604         int ret;
 605         unsigned long offset;
 606         struct btrfs_disk_key *tmp;
 607
 608         while(low < high) {
 609                 mid = (low + high) / 2;
 610                 offset = p + mid * item_size;
 611
 612                 tmp = (struct btrfs_disk_key *)(eb->data + offset);
 613                 ret = btrfs_comp_keys(tmp, key);
 614
 615                 if (ret < 0)
 616                         low = mid + 1;
 617                 else if (ret > 0)
 618                         high = mid;
 619                 else {
 620                         *slot = mid;
 621                         return 0;
 622                 }
 623         }
 624         *slot = low;
 625         return 1;
 626 }
 627
 628 /*
 629  * simple bin_search frontend that does the right thing for
 630  * leaves vs nodes
 631  */
 632 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 633                       int level, int *slot)
 634 {
 635         if (level == 0) {
 636                 return generic_bin_search(eb,
 637                                           offsetof(struct btrfs_leaf, items),
 638                                           sizeof(struct btrfs_item),
 639                                           key, btrfs_header_nritems(eb),
 640                                           slot);
 641         } else {
 642                 return generic_bin_search(eb,
 643                                           offsetof(struct btrfs_node, ptrs),
 644                                           sizeof(struct btrfs_key_ptr),
 645                                           key, btrfs_header_nritems(eb),
 646                                           slot);
 647         }
 648         return -1;
 649 }
 650
 651 static struct extent_buffer *read_node_slot(struct btrfs_root *root,
 652                                    struct extent_buffer *parent, int slot)
 653 {
 654         if (slot < 0)
 655                 return NULL;
 656         if (slot >= btrfs_header_nritems(parent))
 657                 return NULL;
 658         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 659                        btrfs_level_size(root, btrfs_header_level(parent) - 1));
 660 }
 661
 662 static int balance_level(struct btrfs_trans_handle *trans,
 663                          struct btrfs_root *root,
 664                          struct btrfs_path *path, int level)
 665 {
 666         struct extent_buffer *right = NULL;
 667         struct extent_buffer *mid;
 668         struct extent_buffer *left = NULL;
 669         struct extent_buffer *parent = NULL;
 670         int ret = 0;
 671         int wret;
 672         int pslot;
 673         int orig_slot = path->slots[level];
 674         int err_on_enospc = 0;
 675         u64 orig_ptr;
 676
 677         if (level == 0)
 678                 return 0;
 679
 680         mid = path->nodes[level];
 681         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 682
 683         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 684
 685         if (level < BTRFS_MAX_LEVEL - 1)
 686                 parent = path->nodes[level + 1];
 687         pslot = path->slots[level + 1];
 688
 689         /*
 690          * deal with the case where there is only one pointer in the root
 691          * by promoting the node below to a root
 692          */
 693         if (!parent) {
 694                 struct extent_buffer *child;
 695
 696                 if (btrfs_header_nritems(mid) != 1)
 697                         return 0;
 698
 699                 /* promote the child to a root */
 700                 child = read_node_slot(root, mid, 0);
 701                 BUG_ON(!child);
 702                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
 703                 BUG_ON(ret);
 704
 705                 root->node = child;
 706                 add_root_to_dirty_list(root);
 707                 path->nodes[level] = NULL;
 708                 clean_tree_block(trans, root, mid);
 709                 wait_on_tree_block_writeback(root, mid);
 710                 /* once for the path */
 711                 free_extent_buffer(mid);
 712                 ret = btrfs_free_extent(trans, root, mid->start, mid->len,
 713                                         root->root_key.objectid,
 714                                         btrfs_header_generation(mid), 0, 0, 1);
 715                 /* once for the root ptr */
 716                 free_extent_buffer(mid);
 717                 return ret;
 718         }
 719         if (btrfs_header_nritems(mid) >
 720             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 721                 return 0;
 722
 723         if (btrfs_header_nritems(mid) < 2)
 724                 err_on_enospc = 1;
 725
 726         left = read_node_slot(root, parent, pslot - 1);
 727         if (left) {
 728                 wret = btrfs_cow_block(trans, root, left,
 729                                        parent, pslot - 1, &left);
 730                 if (wret) {
 731                         ret = wret;
 732                         goto enospc;
 733                 }
 734         }
 735         right = read_node_slot(root, parent, pslot + 1);
 736         if (right) {
 737                 wret = btrfs_cow_block(trans, root, right,
 738                                        parent, pslot + 1, &right);
 739                 if (wret) {
 740                         ret = wret;
 741                         goto enospc;
 742                 }
 743         }
 744
 745         /* first, try to make some room in the middle buffer */
 746         if (left) {
 747                 orig_slot += btrfs_header_nritems(left);
 748                 wret = push_node_left(trans, root, left, mid, 1);
 749                 if (wret < 0)
 750                         ret = wret;
 751                 if (btrfs_header_nritems(mid) < 2)
 752                         err_on_enospc = 1;
 753         }
 754
 755         /*
 756          * then try to empty the right most buffer into the middle
 757          */
 758         if (right) {
 759                 wret = push_node_left(trans, root, mid, right, 1);
 760                 if (wret < 0 && wret != -ENOSPC)
 761                         ret = wret;
 762                 if (btrfs_header_nritems(right) == 0) {
 763                         u64 bytenr = right->start;
 764                         u64 generation = btrfs_header_generation(parent);
 765                         u32 blocksize = right->len;
 766
 767                         clean_tree_block(trans, root, right);
 768                         wait_on_tree_block_writeback(root, right);
 769                         free_extent_buffer(right);
 770                         right = NULL;
 771                         wret = del_ptr(trans, root, path, level + 1, pslot +
 772                                        1);
 773                         if (wret)
 774                                 ret = wret;
 775                         wret = btrfs_free_extent(trans, root, bytenr,
 776                                                  blocksize,
 777                                                  btrfs_header_owner(parent),
 778                                                  generation, 0, 0, 1);
 779                         if (wret)
 780                                 ret = wret;
 781                 } else {
 782                         struct btrfs_disk_key right_key;
 783                         btrfs_node_key(right, &right_key, 0);
 784                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 785                         btrfs_mark_buffer_dirty(parent);
 786                 }
 787         }
 788         if (btrfs_header_nritems(mid) == 1) {
 789                 /*
 790                  * we're not allowed to leave a node with one item in the
 791                  * tree during a delete.  A deletion from lower in the tree
 792                  * could try to delete the only pointer in this node.
 793                  * So, pull some keys from the left.
 794                  * There has to be a left pointer at this point because
 795                  * otherwise we would have pulled some pointers from the
 796                  * right
 797                  */
 798                 BUG_ON(!left);
 799                 wret = balance_node_right(trans, root, mid, left);
 800                 if (wret < 0) {
 801                         ret = wret;
 802                         goto enospc;
 803                 }
 804                 if (wret == 1) {
 805                         wret = push_node_left(trans, root, left, mid, 1);
 806                         if (wret < 0)
 807                                 ret = wret;
 808                 }
 809                 BUG_ON(wret == 1);
 810         }
 811         if (btrfs_header_nritems(mid) == 0) {
 812                 /* we've managed to empty the middle node, drop it */
 813                 u64 root_gen = btrfs_header_generation(parent);
 814                 u64 bytenr = mid->start;
 815                 u32 blocksize = mid->len;
 816                 clean_tree_block(trans, root, mid);
 817                 wait_on_tree_block_writeback(root, mid);
 818                 free_extent_buffer(mid);
 819                 mid = NULL;
 820                 wret = del_ptr(trans, root, path, level + 1, pslot);
 821                 if (wret)
 822                         ret = wret;
 823                 wret = btrfs_free_extent(trans, root, bytenr, blocksize,
 824                                          btrfs_header_owner(parent),
 825                                          root_gen, 0, 0, 1);
 826                 if (wret)
 827                         ret = wret;
 828         } else {
 829                 /* update the parent key to reflect our changes */
 830                 struct btrfs_disk_key mid_key;
 831                 btrfs_node_key(mid, &mid_key, 0);
 832                 btrfs_set_node_key(parent, &mid_key, pslot);
 833                 btrfs_mark_buffer_dirty(parent);
 834         }
 835
 836         /* update the path */
 837         if (left) {
 838                 if (btrfs_header_nritems(left) > orig_slot) {
 839                         extent_buffer_get(left);
 840                         path->nodes[level] = left;
 841                         path->slots[level + 1] -= 1;
 842                         path->slots[level] = orig_slot;
 843                         if (mid)
 844                                 free_extent_buffer(mid);
 845                 } else {
 846                         orig_slot -= btrfs_header_nritems(left);
 847                         path->slots[level] = orig_slot;
 848                 }
 849         }
 850         /* double check we haven't messed things up */
 851         check_block(root, path, level);
 852         if (orig_ptr !=
 853             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 854                 BUG();
 855 enospc:
 856         if (right)
 857                 free_extent_buffer(right);
 858         if (left)
 859                 free_extent_buffer(left);
 860         return ret;
 861 }
 862
 863 /* returns zero if the push worked, non-zero otherwise */
 864 static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
 865                                           struct btrfs_root *root,
 866                                           struct btrfs_path *path, int level)
 867 {
 868         struct extent_buffer *right = NULL;
 869         struct extent_buffer *mid;
 870         struct extent_buffer *left = NULL;
 871         struct extent_buffer *parent = NULL;
 872         int ret = 0;
 873         int wret;
 874         int pslot;
 875         int orig_slot = path->slots[level];
 876         u64 orig_ptr;
 877
 878         if (level == 0)
 879                 return 1;
 880
 881         mid = path->nodes[level];
 882         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 883         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 884
 885         if (level < BTRFS_MAX_LEVEL - 1)
 886                 parent = path->nodes[level + 1];
 887         pslot = path->slots[level + 1];
 888
 889         if (!parent)
 890                 return 1;
 891
 892         left = read_node_slot(root, parent, pslot - 1);
 893
 894         /* first, try to make some room in the middle buffer */
 895         if (left) {
 896                 u32 left_nr;
 897                 left_nr = btrfs_header_nritems(left);
 898                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 899                         wret = 1;
 900                 } else {
 901                         ret = btrfs_cow_block(trans, root, left, parent,
 902                                               pslot - 1, &left);
 903                         if (ret)
 904                                 wret = 1;
 905                         else {
 906                                 wret = push_node_left(trans, root,
 907                                                       left, mid, 0);
 908                         }
 909                 }
 910                 if (wret < 0)
 911                         ret = wret;
 912                 if (wret == 0) {
 913                         struct btrfs_disk_key disk_key;
 914                         orig_slot += left_nr;
 915                         btrfs_node_key(mid, &disk_key, 0);
 916                         btrfs_set_node_key(parent, &disk_key, pslot);
 917                         btrfs_mark_buffer_dirty(parent);
 918                         if (btrfs_header_nritems(left) > orig_slot) {
 919                                 path->nodes[level] = left;
 920                                 path->slots[level + 1] -= 1;
 921                                 path->slots[level] = orig_slot;
 922                                 free_extent_buffer(mid);
 923                         } else {
 924                                 orig_slot -=
 925                                         btrfs_header_nritems(left);
 926                                 path->slots[level] = orig_slot;
 927                                 free_extent_buffer(left);
 928                         }
 929                         return 0;
 930                 }
 931                 free_extent_buffer(left);
 932         }
 933         right= read_node_slot(root, parent, pslot + 1);
 934
 935         /*
 936          * then try to empty the right most buffer into the middle
 937          */
 938         if (right) {
 939                 u32 right_nr;
 940                 right_nr = btrfs_header_nritems(right);
 941                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 942                         wret = 1;
 943                 } else {
 944                         ret = btrfs_cow_block(trans, root, right,
 945                                               parent, pslot + 1,
 946                                               &right);
 947                         if (ret)
 948                                 wret = 1;
 949                         else {
 950                                 wret = balance_node_right(trans, root,
 951                                                           right, mid);
 952                         }
 953                 }
 954                 if (wret < 0)
 955                         ret = wret;
 956                 if (wret == 0) {
 957                         struct btrfs_disk_key disk_key;
 958
 959                         btrfs_node_key(right, &disk_key, 0);
 960                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
 961                         btrfs_mark_buffer_dirty(parent);
 962
 963                         if (btrfs_header_nritems(mid) <= orig_slot) {
 964                                 path->nodes[level] = right;
 965                                 path->slots[level + 1] += 1;
 966                                 path->slots[level] = orig_slot -
 967                                         btrfs_header_nritems(mid);
 968                                 free_extent_buffer(mid);
 969                         } else {
 970                                 free_extent_buffer(right);
 971                         }
 972                         return 0;
 973                 }
 974                 free_extent_buffer(right);
 975         }
 976         return 1;
 977 }
 978
 979 /*
 980  * readahead one full node of leaves
 981  */
 982 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 983                              int level, int slot, u64 objectid)
 984 {
 985         struct extent_buffer *node;
 986         struct btrfs_disk_key disk_key;
 987         u32 nritems;
 988         u64 search;
 989         u64 lowest_read;
 990         u64 highest_read;
 991         u64 nread = 0;
 992         int direction = path->reada;
 993         struct extent_buffer *eb;
 994         u32 nr;
 995         u32 blocksize;
 996         u32 nscan = 0;
 997
 998         if (level != 1)
 999                 return;
1000
1001         if (!path->nodes[level])
1002                 return;
1003
1004         node = path->nodes[level];
1005         search = btrfs_node_blockptr(node, slot);
1006         blocksize = btrfs_level_size(root, level - 1);
1007         eb = btrfs_find_tree_block(root, search, blocksize);
1008         if (eb) {
1009                 free_extent_buffer(eb);
1010                 return;
1011         }
1012
1013         highest_read = search;
1014         lowest_read = search;
1015
1016         nritems = btrfs_header_nritems(node);
1017         nr = slot;
1018         while(1) {
1019                 if (direction < 0) {
1020                         if (nr == 0)
1021                                 break;
1022                         nr--;
1023                 } else if (direction > 0) {
1024                         nr++;
1025                         if (nr >= nritems)
1026                                 break;
1027                 }
1028                 if (path->reada < 0 && objectid) {
1029                         btrfs_node_key(node, &disk_key, nr);
1030                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1031                                 break;
1032                 }
1033                 search = btrfs_node_blockptr(node, nr);
1034                 if ((search >= lowest_read && search <= highest_read) ||
1035                     (search < lowest_read && lowest_read - search <= 32768) ||
1036                     (search > highest_read && search - highest_read <= 32768)) {
1037                         readahead_tree_block(root, search, blocksize);
1038                         nread += blocksize;
1039                 }
1040                 nscan++;
1041                 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
1042                         break;
1043                 if(nread > (1024 * 1024) || nscan > 128)
1044                         break;
1045
1046                 if (search < lowest_read)
1047                         lowest_read = search;
1048                 if (search > highest_read)
1049                         highest_read = search;
1050         }
1051 }
1052
1053 /*
1054  * look for key in the tree.  path is filled in with nodes along the way
1055  * if key is found, we return zero and you can find the item in the leaf
1056  * level of the path (level 0)
1057  *
1058  * If the key isn't found, the path points to the slot where it should
1059  * be inserted, and 1 is returned.  If there are other errors during the
1060  * search a negative error number is returned.
1061  *
1062  * if ins_len > 0, nodes and leaves will be split as we walk down the
1063  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
1064  * possible)
1065  */
1066 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1067                       *root, struct btrfs_key *key, struct btrfs_path *p, int
1068                       ins_len, int cow)
1069 {
1070         struct extent_buffer *b;
1071         u64 bytenr;
1072         u64 ptr_gen;
1073         int slot;
1074         int ret;
1075         int level;
1076         int should_reada = p->reada;
1077         u8 lowest_level = 0;
1078
1079         lowest_level = p->lowest_level;
1080         WARN_ON(lowest_level && ins_len);
1081         WARN_ON(p->nodes[0] != NULL);
1082         /*
1083         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
1084         */
1085 again:
1086         b = root->node;
1087         extent_buffer_get(b);
1088         while (b) {
1089                 level = btrfs_header_level(b);
1090                 if (cow) {
1091                         int wret;
1092                         wret = btrfs_cow_block(trans, root, b,
1093                                                p->nodes[level + 1],
1094                                                p->slots[level + 1],
1095                                                &b);
1096                         if (wret) {
1097                                 free_extent_buffer(b);
1098                                 return wret;
1099                         }
1100                 }
1101                 BUG_ON(!cow && ins_len);
1102                 if (level != btrfs_header_level(b))
1103                         WARN_ON(1);
1104                 level = btrfs_header_level(b);
1105                 p->nodes[level] = b;
1106                 ret = check_block(root, p, level);
1107                 if (ret)
1108                         return -1;
1109                 ret = bin_search(b, key, level, &slot);
1110                 if (level != 0) {
1111                         if (ret && slot > 0)
1112                                 slot -= 1;
1113                         p->slots[level] = slot;
1114                         if (ins_len > 0 && btrfs_header_nritems(b) >=
1115                             BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
1116                                 int sret = split_node(trans, root, p, level);
1117                                 BUG_ON(sret > 0);
1118                                 if (sret)
1119                                         return sret;
1120                                 b = p->nodes[level];
1121                                 slot = p->slots[level];
1122                         } else if (ins_len < 0) {
1123                                 int sret = balance_level(trans, root, p,
1124                                                          level);
1125                                 if (sret)
1126                                         return sret;
1127                                 b = p->nodes[level];
1128                                 if (!b) {
1129                                         btrfs_release_path(NULL, p);
1130                                         goto again;
1131                                 }
1132                                 slot = p->slots[level];
1133                                 BUG_ON(btrfs_header_nritems(b) == 1);
1134                         }
1135                         /* this is only true while dropping a snapshot */
1136                         if (level == lowest_level)
1137                                 break;
1138                         bytenr = btrfs_node_blockptr(b, slot);
1139                         ptr_gen = btrfs_node_ptr_generation(b, slot);
1140                         if (should_reada)
1141                                 reada_for_search(root, p, level, slot,
1142                                                  key->objectid);
1143                         b = read_tree_block(root, bytenr,
1144                                             btrfs_level_size(root, level - 1));
1145                         if (ptr_gen != btrfs_header_generation(b)) {
1146                                 printk("block %llu bad gen wanted %llu "
1147                                        "found %llu\n",
1148                                 (unsigned long long)b->start,
1149                                 (unsigned long long)ptr_gen,
1150                                 (unsigned long long)btrfs_header_generation(b));
1151                         }
1152                 } else {
1153                         p->slots[level] = slot;
1154                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1155                             sizeof(struct btrfs_item) + ins_len) {
1156                                 int sret = split_leaf(trans, root, key,
1157                                                       p, ins_len, ret == 0);
1158                                 BUG_ON(sret > 0);
1159                                 if (sret)
1160                                         return sret;
1161                         }
1162                         return ret;
1163                 }
1164         }
1165         return 1;
1166 }
1167
1168 /*
1169  * adjust the pointers going up the tree, starting at level
1170  * making sure the right key of each node is points to 'key'.
1171  * This is used after shifting pointers to the left, so it stops
1172  * fixing up pointers when a given leaf/node is not in slot 0 of the
1173  * higher levels
1174  *
1175  * If this fails to write a tree block, it returns -1, but continues
1176  * fixing up the blocks in ram so the tree is consistent.
1177  */
1178 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1179                           struct btrfs_root *root, struct btrfs_path *path,
1180                           struct btrfs_disk_key *key, int level)
1181 {
1182         int i;
1183         int ret = 0;
1184         struct extent_buffer *t;
1185
1186         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1187                 int tslot = path->slots[i];
1188                 if (!path->nodes[i])
1189                         break;
1190                 t = path->nodes[i];
1191                 btrfs_set_node_key(t, key, tslot);
1192                 btrfs_mark_buffer_dirty(path->nodes[i]);
1193                 if (tslot != 0)
1194                         break;
1195         }
1196         return ret;
1197 }
1198
1199 /*
1200  * try to push data from one node into the next node left in the
1201  * tree.
1202  *
1203  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1204  * error, and > 0 if there was no room in the left hand block.
1205  */
1206 static int push_node_left(struct btrfs_trans_handle *trans,
1207                           struct btrfs_root *root, struct extent_buffer *dst,
1208                           struct extent_buffer *src, int empty)
1209 {
1210         int push_items = 0;
1211         int src_nritems;
1212         int dst_nritems;
1213         int ret = 0;
1214
1215         src_nritems = btrfs_header_nritems(src);
1216         dst_nritems = btrfs_header_nritems(dst);
1217         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1218         WARN_ON(btrfs_header_generation(src) != trans->transid);
1219         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1220
1221         if (!empty && src_nritems <= 8)
1222                 return 1;
1223
1224         if (push_items <= 0) {
1225                 return 1;
1226         }
1227
1228         if (empty) {
1229                 push_items = min(src_nritems, push_items);
1230                 if (push_items < src_nritems) {
1231                         /* leave at least 8 pointers in the node if
1232                          * we aren't going to empty it
1233                          */
1234                         if (src_nritems - push_items < 8) {
1235                                 if (push_items <= 8)
1236                                         return 1;
1237                                 push_items -= 8;
1238                         }
1239                 }
1240         } else
1241                 push_items = min(src_nritems - 8, push_items);
1242
1243         copy_extent_buffer(dst, src,
1244                            btrfs_node_key_ptr_offset(dst_nritems),
1245                            btrfs_node_key_ptr_offset(0),
1246                            push_items * sizeof(struct btrfs_key_ptr));
1247
1248         if (push_items < src_nritems) {
1249                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1250                                       btrfs_node_key_ptr_offset(push_items),
1251                                       (src_nritems - push_items) *
1252                                       sizeof(struct btrfs_key_ptr));
1253         }
1254         btrfs_set_header_nritems(src, src_nritems - push_items);
1255         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1256         btrfs_mark_buffer_dirty(src);
1257         btrfs_mark_buffer_dirty(dst);
1258         return ret;
1259 }
1260
1261 /*
1262  * try to push data from one node into the next node right in the
1263  * tree.
1264  *
1265  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1266  * error, and > 0 if there was no room in the right hand block.
1267  *
1268  * this will  only push up to 1/2 the contents of the left node over
1269  */
1270 static int balance_node_right(struct btrfs_trans_handle *trans,
1271                               struct btrfs_root *root,
1272                               struct extent_buffer *dst,
1273                               struct extent_buffer *src)
1274 {
1275         int push_items = 0;
1276         int max_push;
1277         int src_nritems;
1278         int dst_nritems;
1279         int ret = 0;
1280
1281         WARN_ON(btrfs_header_generation(src) != trans->transid);
1282         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1283
1284         src_nritems = btrfs_header_nritems(src);
1285         dst_nritems = btrfs_header_nritems(dst);
1286         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1287         if (push_items <= 0) {
1288                 return 1;
1289         }
1290
1291         if (src_nritems < 4) {
1292                 return 1;
1293         }
1294
1295         max_push = src_nritems / 2 + 1;
1296         /* don't try to empty the node */
1297         if (max_push >= src_nritems) {
1298                 return 1;
1299         }
1300
1301         if (max_push < push_items)
1302                 push_items = max_push;
1303
1304         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1305                                       btrfs_node_key_ptr_offset(0),
1306                                       (dst_nritems) *
1307                                       sizeof(struct btrfs_key_ptr));
1308
1309         copy_extent_buffer(dst, src,
1310                            btrfs_node_key_ptr_offset(0),
1311                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1312                            push_items * sizeof(struct btrfs_key_ptr));
1313
1314         btrfs_set_header_nritems(src, src_nritems - push_items);
1315         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1316
1317         btrfs_mark_buffer_dirty(src);
1318         btrfs_mark_buffer_dirty(dst);
1319         return ret;
1320 }
1321
1322 /*
1323  * helper function to insert a new root level in the tree.
1324  * A new node is allocated, and a single item is inserted to
1325  * point to the existing root
1326  *
1327  * returns zero on success or < 0 on failure.
1328  */
1329 static int noinline insert_new_root(struct btrfs_trans_handle *trans,
1330                            struct btrfs_root *root,
1331                            struct btrfs_path *path, int level)
1332 {
1333         u64 root_gen;
1334         u64 lower_gen;
1335         struct extent_buffer *lower;
1336         struct extent_buffer *c;
1337         struct btrfs_disk_key lower_key;
1338
1339         BUG_ON(path->nodes[level]);
1340         BUG_ON(path->nodes[level-1] != root->node);
1341
1342         if (root->ref_cows)
1343                 root_gen = trans->transid;
1344         else
1345                 root_gen = 0;
1346
1347         lower = path->nodes[level-1];
1348         if (level == 1)
1349                 btrfs_item_key(lower, &lower_key, 0);
1350         else
1351                 btrfs_node_key(lower, &lower_key, 0);
1352
1353         c = __btrfs_alloc_free_block(trans, root, root->nodesize,
1354                                    root->root_key.objectid,
1355                                    root_gen, lower_key.objectid, level,
1356                                    root->node->start, 0);
1357         if (IS_ERR(c))
1358                 return PTR_ERR(c);
1359         memset_extent_buffer(c, 0, 0, root->nodesize);
1360         btrfs_set_header_nritems(c, 1);
1361         btrfs_set_header_level(c, level);
1362         btrfs_set_header_bytenr(c, c->start);
1363         btrfs_set_header_generation(c, trans->transid);
1364         btrfs_set_header_owner(c, root->root_key.objectid);
1365
1366         write_extent_buffer(c, root->fs_info->fsid,
1367                             (unsigned long)btrfs_header_fsid(c),
1368                             BTRFS_FSID_SIZE);
1369
1370         write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
1371                             (unsigned long)btrfs_header_chunk_tree_uuid(c),
1372                             BTRFS_UUID_SIZE);
1373
1374         btrfs_set_node_key(c, &lower_key, 0);
1375         btrfs_set_node_blockptr(c, 0, lower->start);
1376         lower_gen = btrfs_header_generation(lower);
1377         WARN_ON(lower_gen == 0);
1378
1379         btrfs_set_node_ptr_generation(c, 0, lower_gen);
1380
1381         btrfs_mark_buffer_dirty(c);
1382
1383         /* the super has an extra ref to root->node */
1384         free_extent_buffer(root->node);
1385         root->node = c;
1386         add_root_to_dirty_list(root);
1387         extent_buffer_get(c);
1388         path->nodes[level] = c;
1389         path->slots[level] = 0;
1390
1391         if (root->ref_cows && lower_gen != trans->transid) {
1392                 struct btrfs_path *back_path = btrfs_alloc_path();
1393                 int ret;
1394                 ret = btrfs_insert_extent_backref(trans,
1395                                                   root->fs_info->extent_root,
1396                                                   path, lower->start,
1397                                                   root->root_key.objectid,
1398                                                   trans->transid, 0, 0);
1399                 BUG_ON(ret);
1400                 btrfs_free_path(back_path);
1401         }
1402         return 0;
1403 }
1404
1405 /*
1406  * worker function to insert a single pointer in a node.
1407  * the node should have enough room for the pointer already
1408  *
1409  * slot and level indicate where you want the key to go, and
1410  * blocknr is the block the key points to.
1411  *
1412  * returns zero on success and < 0 on any error
1413  */
1414 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1415                       *root, struct btrfs_path *path, struct btrfs_disk_key
1416                       *key, u64 bytenr, int slot, int level)
1417 {
1418         struct extent_buffer *lower;
1419         int nritems;
1420
1421         BUG_ON(!path->nodes[level]);
1422         lower = path->nodes[level];
1423         nritems = btrfs_header_nritems(lower);
1424         if (slot > nritems)
1425                 BUG();
1426         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1427                 BUG();
1428         if (slot != nritems) {
1429                 memmove_extent_buffer(lower,
1430                               btrfs_node_key_ptr_offset(slot + 1),
1431                               btrfs_node_key_ptr_offset(slot),
1432                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1433         }
1434         btrfs_set_node_key(lower, key, slot);
1435         btrfs_set_node_blockptr(lower, slot, bytenr);
1436         WARN_ON(trans->transid == 0);
1437         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
1438         btrfs_set_header_nritems(lower, nritems + 1);
1439         btrfs_mark_buffer_dirty(lower);
1440         return 0;
1441 }
1442
1443 /*
1444  * split the node at the specified level in path in two.
1445  * The path is corrected to point to the appropriate node after the split
1446  *
1447  * Before splitting this tries to make some room in the node by pushing
1448  * left and right, if either one works, it returns right away.
1449  *
1450  * returns 0 on success and < 0 on failure
1451  */
1452 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1453                       *root, struct btrfs_path *path, int level)
1454 {
1455         u64 root_gen;
1456         struct extent_buffer *c;
1457         struct extent_buffer *split;
1458         struct btrfs_disk_key disk_key;
1459         int mid;
1460         int ret;
1461         int wret;
1462         u32 c_nritems;
1463
1464         c = path->nodes[level];
1465         WARN_ON(btrfs_header_generation(c) != trans->transid);
1466         if (c == root->node) {
1467                 /* trying to split the root, lets make a new one */
1468                 ret = insert_new_root(trans, root, path, level + 1);
1469                 if (ret)
1470                         return ret;
1471         } else {
1472                 ret = push_nodes_for_insert(trans, root, path, level);
1473                 c = path->nodes[level];
1474                 if (!ret && btrfs_header_nritems(c) <
1475                     BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
1476                         return 0;
1477                 if (ret < 0)
1478                         return ret;
1479         }
1480
1481         c_nritems = btrfs_header_nritems(c);
1482         if (root->ref_cows)
1483                 root_gen = trans->transid;
1484         else
1485                 root_gen = 0;
1486
1487         btrfs_node_key(c, &disk_key, 0);
1488         split = __btrfs_alloc_free_block(trans, root, root->nodesize,
1489                                          root->root_key.objectid,
1490                                          root_gen,
1491                                          btrfs_disk_key_objectid(&disk_key),
1492                                          level, c->start, 0);
1493         if (IS_ERR(split))
1494                 return PTR_ERR(split);
1495
1496         btrfs_set_header_flags(split, btrfs_header_flags(c));
1497         btrfs_set_header_level(split, btrfs_header_level(c));
1498         btrfs_set_header_bytenr(split, split->start);
1499         btrfs_set_header_generation(split, trans->transid);
1500         btrfs_set_header_owner(split, root->root_key.objectid);
1501         btrfs_set_header_flags(split, 0);
1502         write_extent_buffer(split, root->fs_info->fsid,
1503                             (unsigned long)btrfs_header_fsid(split),
1504                             BTRFS_FSID_SIZE);
1505         write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
1506                             (unsigned long)btrfs_header_chunk_tree_uuid(split),
1507                             BTRFS_UUID_SIZE);
1508
1509         mid = (c_nritems + 1) / 2;
1510
1511         copy_extent_buffer(split, c,
1512                            btrfs_node_key_ptr_offset(0),
1513                            btrfs_node_key_ptr_offset(mid),
1514                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1515         btrfs_set_header_nritems(split, c_nritems - mid);
1516         btrfs_set_header_nritems(c, mid);
1517         ret = 0;
1518
1519         btrfs_mark_buffer_dirty(c);
1520         btrfs_mark_buffer_dirty(split);
1521
1522         btrfs_node_key(split, &disk_key, 0);
1523         wret = insert_ptr(trans, root, path, &disk_key, split->start,
1524                           path->slots[level + 1] + 1,
1525                           level + 1);
1526         if (wret)
1527                 ret = wret;
1528
1529         if (path->slots[level] >= mid) {
1530                 path->slots[level] -= mid;
1531                 free_extent_buffer(c);
1532                 path->nodes[level] = split;
1533                 path->slots[level + 1] += 1;
1534         } else {
1535                 free_extent_buffer(split);
1536         }
1537         return ret;
1538 }
1539
1540 /*
1541  * how many bytes are required to store the items in a leaf.  start
1542  * and nr indicate which items in the leaf to check.  This totals up the
1543  * space used both by the item structs and the item data
1544  */
1545 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1546 {
1547         int data_len;
1548         int nritems = btrfs_header_nritems(l);
1549         int end = min(nritems, start + nr) - 1;
1550
1551         if (!nr)
1552                 return 0;
1553         data_len = btrfs_item_end_nr(l, start);
1554         data_len = data_len - btrfs_item_offset_nr(l, end);
1555         data_len += sizeof(struct btrfs_item) * nr;
1556         WARN_ON(data_len < 0);
1557         return data_len;
1558 }
1559
1560 /*
1561  * The space between the end of the leaf items and
1562  * the start of the leaf data.  IOW, how much room
1563  * the leaf has left for both items and data
1564  */
1565 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1566 {
1567         int nritems = btrfs_header_nritems(leaf);
1568         int ret;
1569         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1570         if (ret < 0) {
1571                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1572                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
1573                        leaf_space_used(leaf, 0, nritems), nritems);
1574         }
1575         return ret;
1576 }
1577
1578 /*
1579  * push some data in the path leaf to the right, trying to free up at
1580  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1581  *
1582  * returns 1 if the push failed because the other node didn't have enough
1583  * room, 0 if everything worked out and < 0 if there were major errors.
1584  */
1585 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1586                            *root, struct btrfs_path *path, int data_size,
1587                            int empty)
1588 {
1589         struct extent_buffer *left = path->nodes[0];
1590         struct extent_buffer *right;
1591         struct extent_buffer *upper;
1592         struct btrfs_disk_key disk_key;
1593         int slot;
1594         u32 i;
1595         int free_space;
1596         int push_space = 0;
1597         int push_items = 0;
1598         struct btrfs_item *item;
1599         u32 left_nritems;
1600         u32 nr;
1601         u32 right_nritems;
1602         u32 data_end;
1603         u32 this_item_size;
1604         int ret;
1605
1606         slot = path->slots[1];
1607         if (!path->nodes[1]) {
1608                 return 1;
1609         }
1610         upper = path->nodes[1];
1611         if (slot >= btrfs_header_nritems(upper) - 1)
1612                 return 1;
1613
1614         right = read_tree_block(root, btrfs_node_blockptr(upper, slot + 1),
1615                                 root->leafsize);
1616         free_space = btrfs_leaf_free_space(root, right);
1617         if (free_space < data_size + sizeof(struct btrfs_item)) {
1618                 free_extent_buffer(right);
1619                 return 1;
1620         }
1621
1622         /* cow and double check */
1623         ret = btrfs_cow_block(trans, root, right, upper,
1624                               slot + 1, &right);
1625         if (ret) {
1626                 free_extent_buffer(right);
1627                 return 1;
1628         }
1629         free_space = btrfs_leaf_free_space(root, right);
1630         if (free_space < data_size + sizeof(struct btrfs_item)) {
1631                 free_extent_buffer(right);
1632                 return 1;
1633         }
1634
1635         left_nritems = btrfs_header_nritems(left);
1636         if (left_nritems == 0) {
1637                 free_extent_buffer(right);
1638                 return 1;
1639         }
1640
1641         if (empty)
1642                 nr = 0;
1643         else
1644                 nr = 1;
1645
1646         i = left_nritems - 1;
1647         while (i >= nr) {
1648                 item = btrfs_item_nr(left, i);
1649
1650                 if (path->slots[0] == i)
1651                         push_space += data_size + sizeof(*item);
1652
1653                 this_item_size = btrfs_item_size(left, item);
1654                 if (this_item_size + sizeof(*item) + push_space > free_space)
1655                         break;
1656                 push_items++;
1657                 push_space += this_item_size + sizeof(*item);
1658                 if (i == 0)
1659                         break;
1660                 i--;
1661         }
1662
1663         if (push_items == 0) {
1664                 free_extent_buffer(right);
1665                 return 1;
1666         }
1667
1668         if (!empty && push_items == left_nritems)
1669                 WARN_ON(1);
1670
1671         /* push left to right */
1672         right_nritems = btrfs_header_nritems(right);
1673
1674         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1675         push_space -= leaf_data_end(root, left);
1676
1677         /* make room in the right data area */
1678         data_end = leaf_data_end(root, right);
1679         memmove_extent_buffer(right,
1680                               btrfs_leaf_data(right) + data_end - push_space,
1681                               btrfs_leaf_data(right) + data_end,
1682                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1683
1684         /* copy from the left data area */
1685         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1686                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1687                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1688                      push_space);
1689
1690         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1691                               btrfs_item_nr_offset(0),
1692                               right_nritems * sizeof(struct btrfs_item));
1693
1694         /* copy the items from left to right */
1695         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1696                    btrfs_item_nr_offset(left_nritems - push_items),
1697                    push_items * sizeof(struct btrfs_item));
1698
1699         /* update the item pointers */
1700         right_nritems += push_items;
1701         btrfs_set_header_nritems(right, right_nritems);
1702         push_space = BTRFS_LEAF_DATA_SIZE(root);
1703         for (i = 0; i < right_nritems; i++) {
1704                 item = btrfs_item_nr(right, i);
1705                 push_space -= btrfs_item_size(right, item);
1706                 btrfs_set_item_offset(right, item, push_space);
1707         }
1708
1709         left_nritems -= push_items;
1710         btrfs_set_header_nritems(left, left_nritems);
1711
1712         if (left_nritems)
1713                 btrfs_mark_buffer_dirty(left);
1714         btrfs_mark_buffer_dirty(right);
1715
1716         btrfs_item_key(right, &disk_key, 0);
1717         btrfs_set_node_key(upper, &disk_key, slot + 1);
1718         btrfs_mark_buffer_dirty(upper);
1719
1720         /* then fixup the leaf pointer in the path */
1721         if (path->slots[0] >= left_nritems) {
1722                 path->slots[0] -= left_nritems;
1723                 free_extent_buffer(path->nodes[0]);
1724                 path->nodes[0] = right;
1725                 path->slots[1] += 1;
1726         } else {
1727                 free_extent_buffer(right);
1728         }
1729         return 0;
1730 }
1731 /*
1732  * push some data in the path leaf to the left, trying to free up at
1733  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1734  */
1735 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1736                           *root, struct btrfs_path *path, int data_size,
1737                           int empty)
1738 {
1739         struct btrfs_disk_key disk_key;
1740         struct extent_buffer *right = path->nodes[0];
1741         struct extent_buffer *left;
1742         int slot;
1743         int i;
1744         int free_space;
1745         int push_space = 0;
1746         int push_items = 0;
1747         struct btrfs_item *item;
1748         u32 old_left_nritems;
1749         u32 right_nritems;
1750         u32 nr;
1751         int ret = 0;
1752         int wret;
1753         u32 this_item_size;
1754         u32 old_left_item_size;
1755
1756         slot = path->slots[1];
1757         if (slot == 0)
1758                 return 1;
1759         if (!path->nodes[1])
1760                 return 1;
1761
1762         right_nritems = btrfs_header_nritems(right);
1763         if (right_nritems == 0) {
1764                 return 1;
1765         }
1766
1767         left = read_tree_block(root, btrfs_node_blockptr(path->nodes[1],
1768                                slot - 1), root->leafsize);
1769         free_space = btrfs_leaf_free_space(root, left);
1770         if (free_space < data_size + sizeof(struct btrfs_item)) {
1771                 free_extent_buffer(left);
1772                 return 1;
1773         }
1774
1775         /* cow and double check */
1776         ret = btrfs_cow_block(trans, root, left,
1777                               path->nodes[1], slot - 1, &left);
1778         if (ret) {
1779                 /* we hit -ENOSPC, but it isn't fatal here */
1780                 free_extent_buffer(left);
1781                 return 1;
1782         }
1783
1784         free_space = btrfs_leaf_free_space(root, left);
1785         if (free_space < data_size + sizeof(struct btrfs_item)) {
1786                 free_extent_buffer(left);
1787                 return 1;
1788         }
1789
1790         if (empty)
1791                 nr = right_nritems;
1792         else
1793                 nr = right_nritems - 1;
1794
1795         for (i = 0; i < nr; i++) {
1796                 item = btrfs_item_nr(right, i);
1797
1798                 if (path->slots[0] == i)
1799                         push_space += data_size + sizeof(*item);
1800
1801                 this_item_size = btrfs_item_size(right, item);
1802                 if (this_item_size + sizeof(*item) + push_space > free_space)
1803                         break;
1804
1805                 push_items++;
1806                 push_space += this_item_size + sizeof(*item);
1807         }
1808
1809         if (push_items == 0) {
1810                 free_extent_buffer(left);
1811                 return 1;
1812         }
1813         if (!empty && push_items == btrfs_header_nritems(right))
1814                 WARN_ON(1);
1815
1816         /* push data from right to left */
1817         copy_extent_buffer(left, right,
1818                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1819                            btrfs_item_nr_offset(0),
1820                            push_items * sizeof(struct btrfs_item));
1821
1822         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1823                      btrfs_item_offset_nr(right, push_items -1);
1824
1825         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1826                      leaf_data_end(root, left) - push_space,
1827                      btrfs_leaf_data(right) +
1828                      btrfs_item_offset_nr(right, push_items - 1),
1829                      push_space);
1830         old_left_nritems = btrfs_header_nritems(left);
1831         BUG_ON(old_left_nritems < 0);
1832
1833         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
1834         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1835                 u32 ioff;
1836
1837                 item = btrfs_item_nr(left, i);
1838                 ioff = btrfs_item_offset(left, item);
1839                 btrfs_set_item_offset(left, item,
1840                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
1841         }
1842         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1843
1844         /* fixup right node */
1845         if (push_items > right_nritems) {
1846                 printk("push items %d nr %u\n", push_items, right_nritems);
1847                 WARN_ON(1);
1848         }
1849
1850         if (push_items < right_nritems) {
1851                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
1852                                                   leaf_data_end(root, right);
1853                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
1854                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
1855                                       btrfs_leaf_data(right) +
1856                                       leaf_data_end(root, right), push_space);
1857
1858                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1859                               btrfs_item_nr_offset(push_items),
1860                              (btrfs_header_nritems(right) - push_items) *
1861                              sizeof(struct btrfs_item));
1862         }
1863         right_nritems -= push_items;
1864         btrfs_set_header_nritems(right, right_nritems);
1865         push_space = BTRFS_LEAF_DATA_SIZE(root);
1866         for (i = 0; i < right_nritems; i++) {
1867                 item = btrfs_item_nr(right, i);
1868                 push_space = push_space - btrfs_item_size(right, item);
1869                 btrfs_set_item_offset(right, item, push_space);
1870         }
1871
1872         btrfs_mark_buffer_dirty(left);
1873         if (right_nritems)
1874                 btrfs_mark_buffer_dirty(right);
1875
1876         btrfs_item_key(right, &disk_key, 0);
1877         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1878         if (wret)
1879                 ret = wret;
1880
1881         /* then fixup the leaf pointer in the path */
1882         if (path->slots[0] < push_items) {
1883                 path->slots[0] += old_left_nritems;
1884                 free_extent_buffer(path->nodes[0]);
1885                 path->nodes[0] = left;
1886                 path->slots[1] -= 1;
1887         } else {
1888                 free_extent_buffer(left);
1889                 path->slots[0] -= push_items;
1890         }
1891         BUG_ON(path->slots[0] < 0);
1892         return ret;
1893 }
1894
1895 /*
1896  * split the path's leaf in two, making sure there is at least data_size
1897  * available for the resulting leaf level of the path.
1898  *
1899  * returns 0 if all went well and < 0 on failure.
1900  */
1901 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1902                       *root, struct btrfs_key *ins_key,
1903                       struct btrfs_path *path, int data_size, int extend)
1904 {
1905         u64 root_gen;
1906         struct extent_buffer *l;
1907         u32 nritems;
1908         int mid;
1909         int slot;
1910         struct extent_buffer *right;
1911         int space_needed = data_size + sizeof(struct btrfs_item);
1912         int data_copy_size;
1913         int rt_data_off;
1914         int i;
1915         int ret = 0;
1916         int wret;
1917         int double_split;
1918         int num_doubles = 0;
1919         struct btrfs_disk_key disk_key;
1920
1921         if (extend)
1922                 space_needed = data_size;
1923
1924         if (root->ref_cows)
1925                 root_gen = trans->transid;
1926         else
1927                 root_gen = 0;
1928
1929         /* first try to make some room by pushing left and right */
1930         if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
1931                 wret = push_leaf_right(trans, root, path, data_size, 0);
1932                 if (wret < 0) {
1933                         return wret;
1934                 }
1935                 if (wret) {
1936                         wret = push_leaf_left(trans, root, path, data_size, 0);
1937                         if (wret < 0)
1938                                 return wret;
1939                 }
1940                 l = path->nodes[0];
1941
1942                 /* did the pushes work? */
1943                 if (btrfs_leaf_free_space(root, l) >= space_needed)
1944                         return 0;
1945         }
1946
1947         if (!path->nodes[1]) {
1948                 ret = insert_new_root(trans, root, path, 1);
1949                 if (ret)
1950                         return ret;
1951         }
1952 again:
1953         double_split = 0;
1954         l = path->nodes[0];
1955         slot = path->slots[0];
1956         nritems = btrfs_header_nritems(l);
1957         mid = (nritems + 1)/ 2;
1958
1959         btrfs_item_key(l, &disk_key, 0);
1960
1961         right = __btrfs_alloc_free_block(trans, root, root->leafsize,
1962                                          root->root_key.objectid,
1963                                          root_gen, disk_key.objectid, 0,
1964                                          l->start, 0);
1965         if (IS_ERR(right)) {
1966                 BUG_ON(1);
1967                 return PTR_ERR(right);
1968         }
1969
1970         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1971         btrfs_set_header_bytenr(right, right->start);
1972         btrfs_set_header_generation(right, trans->transid);
1973         btrfs_set_header_owner(right, root->root_key.objectid);
1974         btrfs_set_header_level(right, 0);
1975         write_extent_buffer(right, root->fs_info->fsid,
1976                             (unsigned long)btrfs_header_fsid(right),
1977                             BTRFS_FSID_SIZE);
1978
1979         write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
1980                             (unsigned long)btrfs_header_chunk_tree_uuid(right),
1981                             BTRFS_UUID_SIZE);
1982         if (mid <= slot) {
1983                 if (nritems == 1 ||
1984                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1985                         BTRFS_LEAF_DATA_SIZE(root)) {
1986                         if (slot >= nritems) {
1987                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1988                                 btrfs_set_header_nritems(right, 0);
1989                                 wret = insert_ptr(trans, root, path,
1990                                                   &disk_key, right->start,
1991                                                   path->slots[1] + 1, 1);
1992                                 if (wret)
1993                                         ret = wret;
1994                                 free_extent_buffer(path->nodes[0]);
1995                                 path->nodes[0] = right;
1996                                 path->slots[0] = 0;
1997                                 path->slots[1] += 1;
1998                                 return ret;
1999                         }
2000                         mid = slot;
2001                         if (mid != nritems &&
2002                             leaf_space_used(l, mid, nritems - mid) +
2003                             space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
2004                                 double_split = 1;
2005                         }
2006                 }
2007         } else {
2008                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
2009                         BTRFS_LEAF_DATA_SIZE(root)) {
2010                         if (!extend && slot == 0) {
2011                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
2012                                 btrfs_set_header_nritems(right, 0);
2013                                 wret = insert_ptr(trans, root, path,
2014                                                   &disk_key,
2015                                                   right->start,
2016                                                   path->slots[1], 1);
2017                                 if (wret)
2018                                         ret = wret;
2019                                 free_extent_buffer(path->nodes[0]);
2020                                 path->nodes[0] = right;
2021                                 path->slots[0] = 0;
2022                                 if (path->slots[1] == 0) {
2023                                         wret = fixup_low_keys(trans, root,
2024                                                    path, &disk_key, 1);
2025                                         if (wret)
2026                                                 ret = wret;
2027                                 }
2028                                 return ret;
2029                         } else if (extend && slot == 0) {
2030                                 mid = 1;
2031                         } else {
2032                                 mid = slot;
2033                                 if (mid != nritems &&
2034                                     leaf_space_used(l, mid, nritems - mid) +
2035                                     space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
2036                                         double_split = 1;
2037                                 }
2038                         }
2039                 }
2040         }
2041         nritems = nritems - mid;
2042         btrfs_set_header_nritems(right, nritems);
2043         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
2044
2045         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2046                            btrfs_item_nr_offset(mid),
2047                            nritems * sizeof(struct btrfs_item));
2048
2049         copy_extent_buffer(right, l,
2050                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2051                      data_copy_size, btrfs_leaf_data(l) +
2052                      leaf_data_end(root, l), data_copy_size);
2053
2054         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2055                       btrfs_item_end_nr(l, mid);
2056
2057         for (i = 0; i < nritems; i++) {
2058                 struct btrfs_item *item = btrfs_item_nr(right, i);
2059                 u32 ioff = btrfs_item_offset(right, item);
2060                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2061         }
2062
2063         btrfs_set_header_nritems(l, mid);
2064         ret = 0;
2065         btrfs_item_key(right, &disk_key, 0);
2066         wret = insert_ptr(trans, root, path, &disk_key, right->start,
2067                           path->slots[1] + 1, 1);
2068         if (wret)
2069                 ret = wret;
2070
2071         btrfs_mark_buffer_dirty(right);
2072         btrfs_mark_buffer_dirty(l);
2073         BUG_ON(path->slots[0] != slot);
2074
2075         if (mid <= slot) {
2076                 free_extent_buffer(path->nodes[0]);
2077                 path->nodes[0] = right;
2078                 path->slots[0] -= mid;
2079                 path->slots[1] += 1;
2080         } else
2081                 free_extent_buffer(right);
2082
2083         BUG_ON(path->slots[0] < 0);
2084
2085         if (double_split) {
2086                 BUG_ON(num_doubles != 0);
2087                 num_doubles++;
2088                 goto again;
2089         }
2090         return ret;
2091 }
2092
2093 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
2094                         struct btrfs_root *root,
2095                         struct btrfs_path *path,
2096                         u32 new_size, int from_end)
2097 {
2098         int ret = 0;
2099         int slot;
2100         int slot_orig;
2101         struct extent_buffer *leaf;
2102         struct btrfs_item *item;
2103         u32 nritems;
2104         unsigned int data_end;
2105         unsigned int old_data_start;
2106         unsigned int old_size;
2107         unsigned int size_diff;
2108         int i;
2109
2110         slot_orig = path->slots[0];
2111         leaf = path->nodes[0];
2112         slot = path->slots[0];
2113
2114         old_size = btrfs_item_size_nr(leaf, slot);
2115         if (old_size == new_size)
2116                 return 0;
2117
2118         nritems = btrfs_header_nritems(leaf);
2119         data_end = leaf_data_end(root, leaf);
2120
2121         old_data_start = btrfs_item_offset_nr(leaf, slot);
2122
2123         size_diff = old_size - new_size;
2124
2125         BUG_ON(slot < 0);
2126         BUG_ON(slot >= nritems);
2127
2128         /*
2129          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2130          */
2131         /* first correct the data pointers */
2132         for (i = slot; i < nritems; i++) {
2133                 u32 ioff;
2134                 item = btrfs_item_nr(leaf, i);
2135                 ioff = btrfs_item_offset(leaf, item);
2136                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2137         }
2138
2139         /* shift the data */
2140         if (from_end) {
2141                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2142                               data_end + size_diff, btrfs_leaf_data(leaf) +
2143                               data_end, old_data_start + new_size - data_end);
2144         } else {
2145                 struct btrfs_disk_key disk_key;
2146                 u64 offset;
2147
2148                 btrfs_item_key(leaf, &disk_key, slot);
2149
2150                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
2151                         unsigned long ptr;
2152                         struct btrfs_file_extent_item *fi;
2153
2154                         fi = btrfs_item_ptr(leaf, slot,
2155                                             struct btrfs_file_extent_item);
2156                         fi = (struct btrfs_file_extent_item *)(
2157                              (unsigned long)fi - size_diff);
2158
2159                         if (btrfs_file_extent_type(leaf, fi) ==
2160                             BTRFS_FILE_EXTENT_INLINE) {
2161                                 ptr = btrfs_item_ptr_offset(leaf, slot);
2162                                 memmove_extent_buffer(leaf, ptr,
2163                                         (unsigned long)fi,
2164                                         offsetof(struct btrfs_file_extent_item,
2165                                                  disk_bytenr));
2166                         }
2167                 }
2168
2169                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2170                               data_end + size_diff, btrfs_leaf_data(leaf) +
2171                               data_end, old_data_start - data_end);
2172
2173                 offset = btrfs_disk_key_offset(&disk_key);
2174                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
2175                 btrfs_set_item_key(leaf, &disk_key, slot);
2176                 if (slot == 0)
2177                         fixup_low_keys(trans, root, path, &disk_key, 1);
2178         }
2179
2180         item = btrfs_item_nr(leaf, slot);
2181         btrfs_set_item_size(leaf, item, new_size);
2182         btrfs_mark_buffer_dirty(leaf);
2183
2184         ret = 0;
2185         if (btrfs_leaf_free_space(root, leaf) < 0) {
2186                 btrfs_print_leaf(root, leaf);
2187                 BUG();
2188         }
2189         return ret;
2190 }
2191
2192 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2193                       struct btrfs_root *root, struct btrfs_path *path,
2194                       u32 data_size)
2195 {
2196         int ret = 0;
2197         int slot;
2198         int slot_orig;
2199         struct extent_buffer *leaf;
2200         struct btrfs_item *item;
2201         u32 nritems;
2202         unsigned int data_end;
2203         unsigned int old_data;
2204         unsigned int old_size;
2205         int i;
2206
2207         slot_orig = path->slots[0];
2208         leaf = path->nodes[0];
2209
2210         nritems = btrfs_header_nritems(leaf);
2211         data_end = leaf_data_end(root, leaf);
2212
2213         if (btrfs_leaf_free_space(root, leaf) < data_size) {
2214                 btrfs_print_leaf(root, leaf);
2215                 BUG();
2216         }
2217         slot = path->slots[0];
2218         old_data = btrfs_item_end_nr(leaf, slot);
2219
2220         BUG_ON(slot < 0);
2221         if (slot >= nritems) {
2222                 btrfs_print_leaf(root, leaf);
2223                 printk("slot %d too large, nritems %d\n", slot, nritems);
2224                 BUG_ON(1);
2225         }
2226
2227         /*
2228          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2229          */
2230         /* first correct the data pointers */
2231         for (i = slot; i < nritems; i++) {
2232                 u32 ioff;
2233                 item = btrfs_item_nr(leaf, i);
2234                 ioff = btrfs_item_offset(leaf, item);
2235                 btrfs_set_item_offset(leaf, item, ioff - data_size);
2236         }
2237
2238         /* shift the data */
2239         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2240                       data_end - data_size, btrfs_leaf_data(leaf) +
2241                       data_end, old_data - data_end);
2242
2243         data_end = old_data;
2244         old_size = btrfs_item_size_nr(leaf, slot);
2245         item = btrfs_item_nr(leaf, slot);
2246         btrfs_set_item_size(leaf, item, old_size + data_size);
2247         btrfs_mark_buffer_dirty(leaf);
2248
2249         ret = 0;
2250         if (btrfs_leaf_free_space(root, leaf) < 0) {
2251                 btrfs_print_leaf(root, leaf);
2252                 BUG();
2253         }
2254         return ret;
2255 }
2256
2257 /*
2258  * Given a key and some data, insert an item into the tree.
2259  * This does all the path init required, making room in the tree if needed.
2260  */
2261 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
2262                             struct btrfs_root *root,
2263                             struct btrfs_path *path,
2264                             struct btrfs_key *cpu_key, u32 *data_size,
2265                             int nr)
2266 {
2267         struct extent_buffer *leaf;
2268         struct btrfs_item *item;
2269         int ret = 0;
2270         int slot;
2271         int slot_orig;
2272         int i;
2273         u32 nritems;
2274         u32 total_size = 0;
2275         u32 total_data = 0;
2276         unsigned int data_end;
2277         struct btrfs_disk_key disk_key;
2278
2279         for (i = 0; i < nr; i++) {
2280                 total_data += data_size[i];
2281         }
2282
2283         /* create a root if there isn't one */
2284         if (!root->node)
2285                 BUG();
2286
2287         total_size = total_data + (nr - 1) * sizeof(struct btrfs_item);
2288         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
2289         if (ret == 0) {
2290                 return -EEXIST;
2291         }
2292         if (ret < 0)
2293                 goto out;
2294
2295         slot_orig = path->slots[0];
2296         leaf = path->nodes[0];
2297
2298         nritems = btrfs_header_nritems(leaf);
2299         data_end = leaf_data_end(root, leaf);
2300
2301         if (btrfs_leaf_free_space(root, leaf) <
2302             sizeof(struct btrfs_item) + total_size) {
2303                 btrfs_print_leaf(root, leaf);
2304                 printk("not enough freespace need %u have %d\n",
2305                        total_size, btrfs_leaf_free_space(root, leaf));
2306                 BUG();
2307         }
2308
2309         slot = path->slots[0];
2310         BUG_ON(slot < 0);
2311
2312         if (slot != nritems) {
2313                 int i;
2314                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2315
2316                 if (old_data < data_end) {
2317                         btrfs_print_leaf(root, leaf);
2318                         printk("slot %d old_data %d data_end %d\n",
2319                                slot, old_data, data_end);
2320                         BUG_ON(1);
2321                 }
2322                 /*
2323                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2324                  */
2325                 /* first correct the data pointers */
2326                 for (i = slot; i < nritems; i++) {
2327                         u32 ioff;
2328
2329                         item = btrfs_item_nr(leaf, i);
2330                         ioff = btrfs_item_offset(leaf, item);
2331                         btrfs_set_item_offset(leaf, item, ioff - total_data);
2332                 }
2333
2334                 /* shift the items */
2335                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
2336                               btrfs_item_nr_offset(slot),
2337                               (nritems - slot) * sizeof(struct btrfs_item));
2338
2339                 /* shift the data */
2340                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2341                               data_end - total_data, btrfs_leaf_data(leaf) +
2342                               data_end, old_data - data_end);
2343                 data_end = old_data;
2344         }
2345
2346         /* setup the item for the new data */
2347         for (i = 0; i < nr; i++) {
2348                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
2349                 btrfs_set_item_key(leaf, &disk_key, slot + i);
2350                 item = btrfs_item_nr(leaf, slot + i);
2351                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
2352                 data_end -= data_size[i];
2353                 btrfs_set_item_size(leaf, item, data_size[i]);
2354         }
2355         btrfs_set_header_nritems(leaf, nritems + nr);
2356         btrfs_mark_buffer_dirty(leaf);
2357
2358         ret = 0;
2359         if (slot == 0) {
2360                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2361                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2362         }
2363
2364         if (btrfs_leaf_free_space(root, leaf) < 0) {
2365                 btrfs_print_leaf(root, leaf);
2366                 BUG();
2367         }
2368
2369 out:
2370         return ret;
2371 }
2372
2373 /*
2374  * Given a key and some data, insert an item into the tree.
2375  * This does all the path init required, making room in the tree if needed.
2376  */
2377 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2378                       *root, struct btrfs_key *cpu_key, void *data, u32
2379                       data_size)
2380 {
2381         int ret = 0;
2382         struct btrfs_path *path;
2383         struct extent_buffer *leaf;
2384         unsigned long ptr;
2385
2386         path = btrfs_alloc_path();
2387         BUG_ON(!path);
2388         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2389         if (!ret) {
2390                 leaf = path->nodes[0];
2391                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2392                 write_extent_buffer(leaf, data, ptr, data_size);
2393                 btrfs_mark_buffer_dirty(leaf);
2394         }
2395         btrfs_free_path(path);
2396         return ret;
2397 }
2398
2399 /*
2400  * delete the pointer from a given node.
2401  *
2402  * If the delete empties a node, the node is removed from the tree,
2403  * continuing all the way the root if required.  The root is converted into
2404  * a leaf if all the nodes are emptied.
2405  */
2406 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2407                    struct btrfs_path *path, int level, int slot)
2408 {
2409         struct extent_buffer *parent = path->nodes[level];
2410         u32 nritems;
2411         int ret = 0;
2412         int wret;
2413
2414         nritems = btrfs_header_nritems(parent);
2415         if (slot != nritems -1) {
2416                 memmove_extent_buffer(parent,
2417                               btrfs_node_key_ptr_offset(slot),
2418                               btrfs_node_key_ptr_offset(slot + 1),
2419                               sizeof(struct btrfs_key_ptr) *
2420                               (nritems - slot - 1));
2421         }
2422         nritems--;
2423         btrfs_set_header_nritems(parent, nritems);
2424         if (nritems == 0 && parent == root->node) {
2425                 BUG_ON(btrfs_header_level(root->node) != 1);
2426                 /* just turn the root into a leaf and break */
2427                 btrfs_set_header_level(root->node, 0);
2428         } else if (slot == 0) {
2429                 struct btrfs_disk_key disk_key;
2430
2431                 btrfs_node_key(parent, &disk_key, 0);
2432                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2433                 if (wret)
2434                         ret = wret;
2435         }
2436         btrfs_mark_buffer_dirty(parent);
2437         return ret;
2438 }
2439
2440 /*
2441  * delete the item at the leaf level in path.  If that empties
2442  * the leaf, remove it from the tree
2443  */
2444 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2445                     struct btrfs_path *path, int slot, int nr)
2446 {
2447         struct extent_buffer *leaf;
2448         struct btrfs_item *item;
2449         int last_off;
2450         int dsize = 0;
2451         int ret = 0;
2452         int wret;
2453         int i;
2454         u32 nritems;
2455
2456         leaf = path->nodes[0];
2457         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
2458
2459         for (i = 0; i < nr; i++)
2460                 dsize += btrfs_item_size_nr(leaf, slot + i);
2461
2462         nritems = btrfs_header_nritems(leaf);
2463
2464         if (slot + nr != nritems) {
2465                 int i;
2466                 int data_end = leaf_data_end(root, leaf);
2467
2468                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2469                               data_end + dsize,
2470                               btrfs_leaf_data(leaf) + data_end,
2471                               last_off - data_end);
2472
2473                 for (i = slot + nr; i < nritems; i++) {
2474                         u32 ioff;
2475
2476                         item = btrfs_item_nr(leaf, i);
2477                         ioff = btrfs_item_offset(leaf, item);
2478                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2479                 }
2480
2481                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2482                               btrfs_item_nr_offset(slot + nr),
2483                               sizeof(struct btrfs_item) *
2484                               (nritems - slot - nr));
2485         }
2486         btrfs_set_header_nritems(leaf, nritems - nr);
2487         nritems -= nr;
2488
2489         /* delete the leaf if we've emptied it */
2490         if (nritems == 0) {
2491                 if (leaf == root->node) {
2492                         btrfs_set_header_level(leaf, 0);
2493                 } else {
2494                         u64 root_gen = btrfs_header_generation(path->nodes[1]);
2495                         clean_tree_block(trans, root, leaf);
2496                         wait_on_tree_block_writeback(root, leaf);
2497                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
2498                         if (wret)
2499                                 ret = wret;
2500                         wret = btrfs_free_extent(trans, root,
2501                                          leaf->start, leaf->len,
2502                                          btrfs_header_owner(path->nodes[1]),
2503                                          root_gen, 0, 0, 1);
2504                         if (wret)
2505                                 ret = wret;
2506                 }
2507         } else {
2508                 int used = leaf_space_used(leaf, 0, nritems);
2509                 if (slot == 0) {
2510                         struct btrfs_disk_key disk_key;
2511
2512                         btrfs_item_key(leaf, &disk_key, 0);
2513                         wret = fixup_low_keys(trans, root, path,
2514                                               &disk_key, 1);
2515                         if (wret)
2516                                 ret = wret;
2517                 }
2518
2519                 /* delete the leaf if it is mostly empty */
2520                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 4) {
2521                         /* push_leaf_left fixes the path.
2522                          * make sure the path still points to our leaf
2523                          * for possible call to del_ptr below
2524                          */
2525                         slot = path->slots[1];
2526                         extent_buffer_get(leaf);
2527
2528                         wret = push_leaf_left(trans, root, path, 1, 1);
2529                         if (wret < 0 && wret != -ENOSPC)
2530                                 ret = wret;
2531
2532                         if (path->nodes[0] == leaf &&
2533                             btrfs_header_nritems(leaf)) {
2534                                 wret = push_leaf_right(trans, root, path, 1, 1);
2535                                 if (wret < 0 && wret != -ENOSPC)
2536                                         ret = wret;
2537                         }
2538
2539                         if (btrfs_header_nritems(leaf) == 0) {
2540                                 u64 root_gen;
2541                                 u64 bytenr = leaf->start;
2542                                 u32 blocksize = leaf->len;
2543
2544                                 root_gen = btrfs_header_generation(
2545                                                            path->nodes[1]);
2546
2547                                 clean_tree_block(trans, root, leaf);
2548                                 wait_on_tree_block_writeback(root, leaf);
2549
2550                                 wret = del_ptr(trans, root, path, 1, slot);
2551                                 if (wret)
2552                                         ret = wret;
2553
2554                                 free_extent_buffer(leaf);
2555                                 wret = btrfs_free_extent(trans, root, bytenr,
2556                                              blocksize,
2557                                              btrfs_header_owner(path->nodes[1]),
2558                                              root_gen, 0, 0, 1);
2559                                 if (wret)
2560                                         ret = wret;
2561                         } else {
2562                                 btrfs_mark_buffer_dirty(leaf);
2563                                 free_extent_buffer(leaf);
2564                         }
2565                 } else {
2566                         btrfs_mark_buffer_dirty(leaf);
2567                 }
2568         }
2569         return ret;
2570 }
2571
2572 /*
2573  * walk up the tree as far as required to find the previous leaf.
2574  * returns 0 if it found something or 1 if there are no lesser leaves.
2575  * returns < 0 on io errors.
2576  */
2577 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2578 {
2579         u64 bytenr;
2580         int slot;
2581         int level = 1;
2582         struct extent_buffer *c;
2583         struct extent_buffer *next = NULL;
2584
2585         while(level < BTRFS_MAX_LEVEL) {
2586                 if (!path->nodes[level])
2587                         return 1;
2588
2589                 slot = path->slots[level];
2590                 c = path->nodes[level];
2591                 if (slot == 0) {
2592                         level++;
2593                         if (level == BTRFS_MAX_LEVEL)
2594                                 return 1;
2595                         continue;
2596                 }
2597                 slot--;
2598
2599                 bytenr = btrfs_node_blockptr(c, slot);
2600                 if (next)
2601                         free_extent_buffer(next);
2602
2603                 next = read_tree_block(root, bytenr,
2604                                        btrfs_level_size(root, level - 1));
2605                 break;
2606         }
2607         path->slots[level] = slot;
2608         while(1) {
2609                 level--;
2610                 c = path->nodes[level];
2611                 free_extent_buffer(c);
2612                 slot = btrfs_header_nritems(next);
2613                 if (slot != 0)
2614                         slot--;
2615                 path->nodes[level] = next;
2616                 path->slots[level] = slot;
2617                 if (!level)
2618                         break;
2619                 next = read_tree_block(root, btrfs_node_blockptr(next, slot),
2620                                        btrfs_level_size(root, level - 1));
2621         }
2622         return 0;
2623 }
2624
2625 /*
2626  * walk up the tree as far as required to find the next leaf.
2627  * returns 0 if it found something or 1 if there are no greater leaves.
2628  * returns < 0 on io errors.
2629  */
2630 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2631 {
2632         int slot;
2633         int level = 1;
2634         u64 bytenr;
2635         struct extent_buffer *c;
2636         struct extent_buffer *next = NULL;
2637
2638         while(level < BTRFS_MAX_LEVEL) {
2639                 if (!path->nodes[level])
2640                         return 1;
2641
2642                 slot = path->slots[level] + 1;
2643                 c = path->nodes[level];
2644                 if (slot >= btrfs_header_nritems(c)) {
2645                         level++;
2646                         if (level == BTRFS_MAX_LEVEL)
2647                                 return 1;
2648                         continue;
2649                 }
2650
2651                 bytenr = btrfs_node_blockptr(c, slot);
2652                 if (next)
2653                         free_extent_buffer(next);
2654
2655                 if (path->reada)
2656                         reada_for_search(root, path, level, slot, 0);
2657
2658                 next = read_tree_block(root, bytenr,
2659                                        btrfs_level_size(root, level -1));
2660                 break;
2661         }
2662         path->slots[level] = slot;
2663         while(1) {
2664                 level--;
2665                 c = path->nodes[level];
2666                 free_extent_buffer(c);
2667                 path->nodes[level] = next;
2668                 path->slots[level] = 0;
2669                 if (!level)
2670                         break;
2671                 if (path->reada)
2672                         reada_for_search(root, path, level, 0, 0);
2673                 next = read_tree_block(root, btrfs_node_blockptr(next, 0),
2674                                        btrfs_level_size(root, level - 1));
2675         }
2676         return 0;
2677 }
2678
2679 int btrfs_previous_item(struct btrfs_root *root,
2680                         struct btrfs_path *path, u64 min_objectid,
2681                         int type)
2682 {
2683         struct btrfs_key found_key;
2684         struct extent_buffer *leaf;
2685         int ret;
2686
2687         while(1) {
2688                 if (path->slots[0] == 0) {
2689                         ret = btrfs_prev_leaf(root, path);
2690                         if (ret != 0)
2691                                 return ret;
2692                 } else {
2693                         path->slots[0]--;
2694                 }
2695                 leaf = path->nodes[0];
2696                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2697                 if (found_key.type == type)
2698                         return 0;
2699         }
2700         return 1;
2701 }
2702