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, 0);
 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                 BUG_ON(wret == 1);
 805         }
 806         if (btrfs_header_nritems(mid) == 0) {
 807                 /* we've managed to empty the middle node, drop it */
 808                 u64 root_gen = btrfs_header_generation(parent);
 809                 u64 bytenr = mid->start;
 810                 u32 blocksize = mid->len;
 811                 clean_tree_block(trans, root, mid);
 812                 wait_on_tree_block_writeback(root, mid);
 813                 free_extent_buffer(mid);
 814                 mid = NULL;
 815                 wret = del_ptr(trans, root, path, level + 1, pslot);
 816                 if (wret)
 817                         ret = wret;
 818                 wret = btrfs_free_extent(trans, root, bytenr, blocksize,
 819                                          btrfs_header_owner(parent),
 820                                          root_gen, 0, 0, 1);
 821                 if (wret)
 822                         ret = wret;
 823         } else {
 824                 /* update the parent key to reflect our changes */
 825                 struct btrfs_disk_key mid_key;
 826                 btrfs_node_key(mid, &mid_key, 0);
 827                 btrfs_set_node_key(parent, &mid_key, pslot);
 828                 btrfs_mark_buffer_dirty(parent);
 829         }
 830
 831         /* update the path */
 832         if (left) {
 833                 if (btrfs_header_nritems(left) > orig_slot) {
 834                         extent_buffer_get(left);
 835                         path->nodes[level] = left;
 836                         path->slots[level + 1] -= 1;
 837                         path->slots[level] = orig_slot;
 838                         if (mid)
 839                                 free_extent_buffer(mid);
 840                 } else {
 841                         orig_slot -= btrfs_header_nritems(left);
 842                         path->slots[level] = orig_slot;
 843                 }
 844         }
 845         /* double check we haven't messed things up */
 846         check_block(root, path, level);
 847         if (orig_ptr !=
 848             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 849                 BUG();
 850 enospc:
 851         if (right)
 852                 free_extent_buffer(right);
 853         if (left)
 854                 free_extent_buffer(left);
 855         return ret;
 856 }
 857
 858 /* returns zero if the push worked, non-zero otherwise */
 859 static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
 860                                           struct btrfs_root *root,
 861                                           struct btrfs_path *path, int level)
 862 {
 863         struct extent_buffer *right = NULL;
 864         struct extent_buffer *mid;
 865         struct extent_buffer *left = NULL;
 866         struct extent_buffer *parent = NULL;
 867         int ret = 0;
 868         int wret;
 869         int pslot;
 870         int orig_slot = path->slots[level];
 871         u64 orig_ptr;
 872
 873         if (level == 0)
 874                 return 1;
 875
 876         mid = path->nodes[level];
 877         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 878         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 879
 880         if (level < BTRFS_MAX_LEVEL - 1)
 881                 parent = path->nodes[level + 1];
 882         pslot = path->slots[level + 1];
 883
 884         if (!parent)
 885                 return 1;
 886
 887         left = read_node_slot(root, parent, pslot - 1);
 888
 889         /* first, try to make some room in the middle buffer */
 890         if (left) {
 891                 u32 left_nr;
 892                 left_nr = btrfs_header_nritems(left);
 893                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 894                         wret = 1;
 895                 } else {
 896                         ret = btrfs_cow_block(trans, root, left, parent,
 897                                               pslot - 1, &left);
 898                         if (ret)
 899                                 wret = 1;
 900                         else {
 901                                 wret = push_node_left(trans, root,
 902                                                       left, mid, 0);
 903                         }
 904                 }
 905                 if (wret < 0)
 906                         ret = wret;
 907                 if (wret == 0) {
 908                         struct btrfs_disk_key disk_key;
 909                         orig_slot += left_nr;
 910                         btrfs_node_key(mid, &disk_key, 0);
 911                         btrfs_set_node_key(parent, &disk_key, pslot);
 912                         btrfs_mark_buffer_dirty(parent);
 913                         if (btrfs_header_nritems(left) > orig_slot) {
 914                                 path->nodes[level] = left;
 915                                 path->slots[level + 1] -= 1;
 916                                 path->slots[level] = orig_slot;
 917                                 free_extent_buffer(mid);
 918                         } else {
 919                                 orig_slot -=
 920                                         btrfs_header_nritems(left);
 921                                 path->slots[level] = orig_slot;
 922                                 free_extent_buffer(left);
 923                         }
 924                         return 0;
 925                 }
 926                 free_extent_buffer(left);
 927         }
 928         right= read_node_slot(root, parent, pslot + 1);
 929
 930         /*
 931          * then try to empty the right most buffer into the middle
 932          */
 933         if (right) {
 934                 u32 right_nr;
 935                 right_nr = btrfs_header_nritems(right);
 936                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 937                         wret = 1;
 938                 } else {
 939                         ret = btrfs_cow_block(trans, root, right,
 940                                               parent, pslot + 1,
 941                                               &right);
 942                         if (ret)
 943                                 wret = 1;
 944                         else {
 945                                 wret = balance_node_right(trans, root,
 946                                                           right, mid);
 947                         }
 948                 }
 949                 if (wret < 0)
 950                         ret = wret;
 951                 if (wret == 0) {
 952                         struct btrfs_disk_key disk_key;
 953
 954                         btrfs_node_key(right, &disk_key, 0);
 955                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
 956                         btrfs_mark_buffer_dirty(parent);
 957
 958                         if (btrfs_header_nritems(mid) <= orig_slot) {
 959                                 path->nodes[level] = right;
 960                                 path->slots[level + 1] += 1;
 961                                 path->slots[level] = orig_slot -
 962                                         btrfs_header_nritems(mid);
 963                                 free_extent_buffer(mid);
 964                         } else {
 965                                 free_extent_buffer(right);
 966                         }
 967                         return 0;
 968                 }
 969                 free_extent_buffer(right);
 970         }
 971         return 1;
 972 }
 973
 974 /*
 975  * readahead one full node of leaves
 976  */
 977 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 978                              int level, int slot, u64 objectid)
 979 {
 980         struct extent_buffer *node;
 981         struct btrfs_disk_key disk_key;
 982         u32 nritems;
 983         u64 search;
 984         u64 lowest_read;
 985         u64 highest_read;
 986         u64 nread = 0;
 987         int direction = path->reada;
 988         struct extent_buffer *eb;
 989         u32 nr;
 990         u32 blocksize;
 991         u32 nscan = 0;
 992
 993         if (level != 1)
 994                 return;
 995
 996         if (!path->nodes[level])
 997                 return;
 998
 999         node = path->nodes[level];
1000         search = btrfs_node_blockptr(node, slot);
1001         blocksize = btrfs_level_size(root, level - 1);
1002         eb = btrfs_find_tree_block(root, search, blocksize);
1003         if (eb) {
1004                 free_extent_buffer(eb);
1005                 return;
1006         }
1007
1008         highest_read = search;
1009         lowest_read = search;
1010
1011         nritems = btrfs_header_nritems(node);
1012         nr = slot;
1013         while(1) {
1014                 if (direction < 0) {
1015                         if (nr == 0)
1016                                 break;
1017                         nr--;
1018                 } else if (direction > 0) {
1019                         nr++;
1020                         if (nr >= nritems)
1021                                 break;
1022                 }
1023                 if (path->reada < 0 && objectid) {
1024                         btrfs_node_key(node, &disk_key, nr);
1025                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1026                                 break;
1027                 }
1028                 search = btrfs_node_blockptr(node, nr);
1029                 if ((search >= lowest_read && search <= highest_read) ||
1030                     (search < lowest_read && lowest_read - search <= 32768) ||
1031                     (search > highest_read && search - highest_read <= 32768)) {
1032                         readahead_tree_block(root, search, blocksize);
1033                         nread += blocksize;
1034                 }
1035                 nscan++;
1036                 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
1037                         break;
1038                 if(nread > (1024 * 1024) || nscan > 128)
1039                         break;
1040
1041                 if (search < lowest_read)
1042                         lowest_read = search;
1043                 if (search > highest_read)
1044                         highest_read = search;
1045         }
1046 }
1047
1048 /*
1049  * look for key in the tree.  path is filled in with nodes along the way
1050  * if key is found, we return zero and you can find the item in the leaf
1051  * level of the path (level 0)
1052  *
1053  * If the key isn't found, the path points to the slot where it should
1054  * be inserted, and 1 is returned.  If there are other errors during the
1055  * search a negative error number is returned.
1056  *
1057  * if ins_len > 0, nodes and leaves will be split as we walk down the
1058  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
1059  * possible)
1060  */
1061 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1062                       *root, struct btrfs_key *key, struct btrfs_path *p, int
1063                       ins_len, int cow)
1064 {
1065         struct extent_buffer *b;
1066         u64 bytenr;
1067         u64 ptr_gen;
1068         int slot;
1069         int ret;
1070         int level;
1071         int should_reada = p->reada;
1072         u8 lowest_level = 0;
1073
1074         lowest_level = p->lowest_level;
1075         WARN_ON(lowest_level && ins_len);
1076         WARN_ON(p->nodes[0] != NULL);
1077         /*
1078         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
1079         */
1080 again:
1081         b = root->node;
1082         extent_buffer_get(b);
1083         while (b) {
1084                 level = btrfs_header_level(b);
1085                 if (cow) {
1086                         int wret;
1087                         wret = btrfs_cow_block(trans, root, b,
1088                                                p->nodes[level + 1],
1089                                                p->slots[level + 1],
1090                                                &b);
1091                         if (wret) {
1092                                 free_extent_buffer(b);
1093                                 return wret;
1094                         }
1095                 }
1096                 BUG_ON(!cow && ins_len);
1097                 if (level != btrfs_header_level(b))
1098                         WARN_ON(1);
1099                 level = btrfs_header_level(b);
1100                 p->nodes[level] = b;
1101                 ret = check_block(root, p, level);
1102                 if (ret)
1103                         return -1;
1104                 ret = bin_search(b, key, level, &slot);
1105                 if (level != 0) {
1106                         if (ret && slot > 0)
1107                                 slot -= 1;
1108                         p->slots[level] = slot;
1109                         if (ins_len > 0 && btrfs_header_nritems(b) >=
1110                             BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
1111                                 int sret = split_node(trans, root, p, level);
1112                                 BUG_ON(sret > 0);
1113                                 if (sret)
1114                                         return sret;
1115                                 b = p->nodes[level];
1116                                 slot = p->slots[level];
1117                         } else if (ins_len < 0) {
1118                                 int sret = balance_level(trans, root, p,
1119                                                          level);
1120                                 if (sret)
1121                                         return sret;
1122                                 b = p->nodes[level];
1123                                 if (!b) {
1124                                         btrfs_release_path(NULL, p);
1125                                         goto again;
1126                                 }
1127                                 slot = p->slots[level];
1128                                 BUG_ON(btrfs_header_nritems(b) == 1);
1129                         }
1130                         /* this is only true while dropping a snapshot */
1131                         if (level == lowest_level)
1132                                 break;
1133                         bytenr = btrfs_node_blockptr(b, slot);
1134                         ptr_gen = btrfs_node_ptr_generation(b, slot);
1135                         if (should_reada)
1136                                 reada_for_search(root, p, level, slot,
1137                                                  key->objectid);
1138                         b = read_tree_block(root, bytenr,
1139                                             btrfs_level_size(root, level - 1));
1140                         if (ptr_gen != btrfs_header_generation(b)) {
1141                                 printk("block %llu bad gen wanted %llu "
1142                                        "found %llu\n",
1143                                 (unsigned long long)b->start,
1144                                 (unsigned long long)ptr_gen,
1145                                 (unsigned long long)btrfs_header_generation(b));
1146                         }
1147                 } else {
1148                         p->slots[level] = slot;
1149                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1150                             sizeof(struct btrfs_item) + ins_len) {
1151                                 int sret = split_leaf(trans, root, key,
1152                                                       p, ins_len, ret == 0);
1153                                 BUG_ON(sret > 0);
1154                                 if (sret)
1155                                         return sret;
1156                         }
1157                         return ret;
1158                 }
1159         }
1160         return 1;
1161 }
1162
1163 /*
1164  * adjust the pointers going up the tree, starting at level
1165  * making sure the right key of each node is points to 'key'.
1166  * This is used after shifting pointers to the left, so it stops
1167  * fixing up pointers when a given leaf/node is not in slot 0 of the
1168  * higher levels
1169  *
1170  * If this fails to write a tree block, it returns -1, but continues
1171  * fixing up the blocks in ram so the tree is consistent.
1172  */
1173 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1174                           struct btrfs_root *root, struct btrfs_path *path,
1175                           struct btrfs_disk_key *key, int level)
1176 {
1177         int i;
1178         int ret = 0;
1179         struct extent_buffer *t;
1180
1181         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1182                 int tslot = path->slots[i];
1183                 if (!path->nodes[i])
1184                         break;
1185                 t = path->nodes[i];
1186                 btrfs_set_node_key(t, key, tslot);
1187                 btrfs_mark_buffer_dirty(path->nodes[i]);
1188                 if (tslot != 0)
1189                         break;
1190         }
1191         return ret;
1192 }
1193
1194 /*
1195  * try to push data from one node into the next node left in the
1196  * tree.
1197  *
1198  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1199  * error, and > 0 if there was no room in the left hand block.
1200  */
1201 static int push_node_left(struct btrfs_trans_handle *trans,
1202                           struct btrfs_root *root, struct extent_buffer *dst,
1203                           struct extent_buffer *src, int empty)
1204 {
1205         int push_items = 0;
1206         int src_nritems;
1207         int dst_nritems;
1208         int ret = 0;
1209
1210         src_nritems = btrfs_header_nritems(src);
1211         dst_nritems = btrfs_header_nritems(dst);
1212         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1213         WARN_ON(btrfs_header_generation(src) != trans->transid);
1214         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1215
1216         if (!empty && src_nritems <= 2)
1217                 return 1;
1218
1219         if (push_items <= 0) {
1220                 return 1;
1221         }
1222
1223         if (empty)
1224                 push_items = min(src_nritems, push_items);
1225         else
1226                 push_items = min(src_nritems - 2, push_items);
1227
1228         copy_extent_buffer(dst, src,
1229                            btrfs_node_key_ptr_offset(dst_nritems),
1230                            btrfs_node_key_ptr_offset(0),
1231                            push_items * sizeof(struct btrfs_key_ptr));
1232
1233         if (push_items < src_nritems) {
1234                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1235                                       btrfs_node_key_ptr_offset(push_items),
1236                                       (src_nritems - push_items) *
1237                                       sizeof(struct btrfs_key_ptr));
1238         }
1239         btrfs_set_header_nritems(src, src_nritems - push_items);
1240         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1241         btrfs_mark_buffer_dirty(src);
1242         btrfs_mark_buffer_dirty(dst);
1243         return ret;
1244 }
1245
1246 /*
1247  * try to push data from one node into the next node right in the
1248  * tree.
1249  *
1250  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1251  * error, and > 0 if there was no room in the right hand block.
1252  *
1253  * this will  only push up to 1/2 the contents of the left node over
1254  */
1255 static int balance_node_right(struct btrfs_trans_handle *trans,
1256                               struct btrfs_root *root,
1257                               struct extent_buffer *dst,
1258                               struct extent_buffer *src)
1259 {
1260         int push_items = 0;
1261         int max_push;
1262         int src_nritems;
1263         int dst_nritems;
1264         int ret = 0;
1265
1266         WARN_ON(btrfs_header_generation(src) != trans->transid);
1267         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1268
1269         src_nritems = btrfs_header_nritems(src);
1270         dst_nritems = btrfs_header_nritems(dst);
1271         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1272         if (push_items <= 0)
1273                 return 1;
1274
1275         max_push = src_nritems / 2 + 1;
1276         /* don't try to empty the node */
1277         if (max_push >= src_nritems)
1278                 return 1;
1279
1280         if (max_push < push_items)
1281                 push_items = max_push;
1282
1283         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1284                                       btrfs_node_key_ptr_offset(0),
1285                                       (dst_nritems) *
1286                                       sizeof(struct btrfs_key_ptr));
1287
1288         copy_extent_buffer(dst, src,
1289                            btrfs_node_key_ptr_offset(0),
1290                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1291                            push_items * sizeof(struct btrfs_key_ptr));
1292
1293         btrfs_set_header_nritems(src, src_nritems - push_items);
1294         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1295
1296         btrfs_mark_buffer_dirty(src);
1297         btrfs_mark_buffer_dirty(dst);
1298         return ret;
1299 }
1300
1301 /*
1302  * helper function to insert a new root level in the tree.
1303  * A new node is allocated, and a single item is inserted to
1304  * point to the existing root
1305  *
1306  * returns zero on success or < 0 on failure.
1307  */
1308 static int noinline insert_new_root(struct btrfs_trans_handle *trans,
1309                            struct btrfs_root *root,
1310                            struct btrfs_path *path, int level)
1311 {
1312         u64 root_gen;
1313         u64 lower_gen;
1314         struct extent_buffer *lower;
1315         struct extent_buffer *c;
1316         struct btrfs_disk_key lower_key;
1317
1318         BUG_ON(path->nodes[level]);
1319         BUG_ON(path->nodes[level-1] != root->node);
1320
1321         if (root->ref_cows)
1322                 root_gen = trans->transid;
1323         else
1324                 root_gen = 0;
1325
1326         lower = path->nodes[level-1];
1327         if (level == 1)
1328                 btrfs_item_key(lower, &lower_key, 0);
1329         else
1330                 btrfs_node_key(lower, &lower_key, 0);
1331
1332         c = __btrfs_alloc_free_block(trans, root, root->nodesize,
1333                                    root->root_key.objectid,
1334                                    root_gen, lower_key.objectid, level,
1335                                    root->node->start, 0);
1336         if (IS_ERR(c))
1337                 return PTR_ERR(c);
1338         memset_extent_buffer(c, 0, 0, root->nodesize);
1339         btrfs_set_header_nritems(c, 1);
1340         btrfs_set_header_level(c, level);
1341         btrfs_set_header_bytenr(c, c->start);
1342         btrfs_set_header_generation(c, trans->transid);
1343         btrfs_set_header_owner(c, root->root_key.objectid);
1344
1345         write_extent_buffer(c, root->fs_info->fsid,
1346                             (unsigned long)btrfs_header_fsid(c),
1347                             BTRFS_FSID_SIZE);
1348
1349         write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
1350                             (unsigned long)btrfs_header_chunk_tree_uuid(c),
1351                             BTRFS_UUID_SIZE);
1352
1353         btrfs_set_node_key(c, &lower_key, 0);
1354         btrfs_set_node_blockptr(c, 0, lower->start);
1355         lower_gen = btrfs_header_generation(lower);
1356         WARN_ON(lower_gen == 0);
1357
1358         btrfs_set_node_ptr_generation(c, 0, lower_gen);
1359
1360         btrfs_mark_buffer_dirty(c);
1361
1362         /* the super has an extra ref to root->node */
1363         free_extent_buffer(root->node);
1364         root->node = c;
1365         add_root_to_dirty_list(root);
1366         extent_buffer_get(c);
1367         path->nodes[level] = c;
1368         path->slots[level] = 0;
1369
1370         if (root->ref_cows && lower_gen != trans->transid) {
1371                 struct btrfs_path *back_path = btrfs_alloc_path();
1372                 int ret;
1373                 ret = btrfs_insert_extent_backref(trans,
1374                                                   root->fs_info->extent_root,
1375                                                   path, lower->start,
1376                                                   root->root_key.objectid,
1377                                                   trans->transid, 0, 0);
1378                 BUG_ON(ret);
1379                 btrfs_free_path(back_path);
1380         }
1381         return 0;
1382 }
1383
1384 /*
1385  * worker function to insert a single pointer in a node.
1386  * the node should have enough room for the pointer already
1387  *
1388  * slot and level indicate where you want the key to go, and
1389  * blocknr is the block the key points to.
1390  *
1391  * returns zero on success and < 0 on any error
1392  */
1393 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1394                       *root, struct btrfs_path *path, struct btrfs_disk_key
1395                       *key, u64 bytenr, int slot, int level)
1396 {
1397         struct extent_buffer *lower;
1398         int nritems;
1399
1400         BUG_ON(!path->nodes[level]);
1401         lower = path->nodes[level];
1402         nritems = btrfs_header_nritems(lower);
1403         if (slot > nritems)
1404                 BUG();
1405         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1406                 BUG();
1407         if (slot != nritems) {
1408                 memmove_extent_buffer(lower,
1409                               btrfs_node_key_ptr_offset(slot + 1),
1410                               btrfs_node_key_ptr_offset(slot),
1411                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1412         }
1413         btrfs_set_node_key(lower, key, slot);
1414         btrfs_set_node_blockptr(lower, slot, bytenr);
1415         WARN_ON(trans->transid == 0);
1416         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
1417         btrfs_set_header_nritems(lower, nritems + 1);
1418         btrfs_mark_buffer_dirty(lower);
1419         return 0;
1420 }
1421
1422 /*
1423  * split the node at the specified level in path in two.
1424  * The path is corrected to point to the appropriate node after the split
1425  *
1426  * Before splitting this tries to make some room in the node by pushing
1427  * left and right, if either one works, it returns right away.
1428  *
1429  * returns 0 on success and < 0 on failure
1430  */
1431 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1432                       *root, struct btrfs_path *path, int level)
1433 {
1434         u64 root_gen;
1435         struct extent_buffer *c;
1436         struct extent_buffer *split;
1437         struct btrfs_disk_key disk_key;
1438         int mid;
1439         int ret;
1440         int wret;
1441         u32 c_nritems;
1442
1443         c = path->nodes[level];
1444         WARN_ON(btrfs_header_generation(c) != trans->transid);
1445         if (c == root->node) {
1446                 /* trying to split the root, lets make a new one */
1447                 ret = insert_new_root(trans, root, path, level + 1);
1448                 if (ret)
1449                         return ret;
1450         } else {
1451                 ret = push_nodes_for_insert(trans, root, path, level);
1452                 c = path->nodes[level];
1453                 if (!ret && btrfs_header_nritems(c) <
1454                     BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
1455                         return 0;
1456                 if (ret < 0)
1457                         return ret;
1458         }
1459
1460         c_nritems = btrfs_header_nritems(c);
1461         if (root->ref_cows)
1462                 root_gen = trans->transid;
1463         else
1464                 root_gen = 0;
1465
1466         btrfs_node_key(c, &disk_key, 0);
1467         split = __btrfs_alloc_free_block(trans, root, root->nodesize,
1468                                          root->root_key.objectid,
1469                                          root_gen,
1470                                          btrfs_disk_key_objectid(&disk_key),
1471                                          level, c->start, 0);
1472         if (IS_ERR(split))
1473                 return PTR_ERR(split);
1474
1475         btrfs_set_header_flags(split, btrfs_header_flags(c));
1476         btrfs_set_header_level(split, btrfs_header_level(c));
1477         btrfs_set_header_bytenr(split, split->start);
1478         btrfs_set_header_generation(split, trans->transid);
1479         btrfs_set_header_owner(split, root->root_key.objectid);
1480         btrfs_set_header_flags(split, 0);
1481         write_extent_buffer(split, root->fs_info->fsid,
1482                             (unsigned long)btrfs_header_fsid(split),
1483                             BTRFS_FSID_SIZE);
1484         write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
1485                             (unsigned long)btrfs_header_chunk_tree_uuid(split),
1486                             BTRFS_UUID_SIZE);
1487
1488         mid = (c_nritems + 1) / 2;
1489
1490         copy_extent_buffer(split, c,
1491                            btrfs_node_key_ptr_offset(0),
1492                            btrfs_node_key_ptr_offset(mid),
1493                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1494         btrfs_set_header_nritems(split, c_nritems - mid);
1495         btrfs_set_header_nritems(c, mid);
1496         ret = 0;
1497
1498         btrfs_mark_buffer_dirty(c);
1499         btrfs_mark_buffer_dirty(split);
1500
1501         btrfs_node_key(split, &disk_key, 0);
1502         wret = insert_ptr(trans, root, path, &disk_key, split->start,
1503                           path->slots[level + 1] + 1,
1504                           level + 1);
1505         if (wret)
1506                 ret = wret;
1507
1508         if (path->slots[level] >= mid) {
1509                 path->slots[level] -= mid;
1510                 free_extent_buffer(c);
1511                 path->nodes[level] = split;
1512                 path->slots[level + 1] += 1;
1513         } else {
1514                 free_extent_buffer(split);
1515         }
1516         return ret;
1517 }
1518
1519 /*
1520  * how many bytes are required to store the items in a leaf.  start
1521  * and nr indicate which items in the leaf to check.  This totals up the
1522  * space used both by the item structs and the item data
1523  */
1524 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1525 {
1526         int data_len;
1527         int nritems = btrfs_header_nritems(l);
1528         int end = min(nritems, start + nr) - 1;
1529
1530         if (!nr)
1531                 return 0;
1532         data_len = btrfs_item_end_nr(l, start);
1533         data_len = data_len - btrfs_item_offset_nr(l, end);
1534         data_len += sizeof(struct btrfs_item) * nr;
1535         WARN_ON(data_len < 0);
1536         return data_len;
1537 }
1538
1539 /*
1540  * The space between the end of the leaf items and
1541  * the start of the leaf data.  IOW, how much room
1542  * the leaf has left for both items and data
1543  */
1544 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1545 {
1546         int nritems = btrfs_header_nritems(leaf);
1547         int ret;
1548         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1549         if (ret < 0) {
1550                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1551                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
1552                        leaf_space_used(leaf, 0, nritems), nritems);
1553         }
1554         return ret;
1555 }
1556
1557 /*
1558  * push some data in the path leaf to the right, trying to free up at
1559  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1560  *
1561  * returns 1 if the push failed because the other node didn't have enough
1562  * room, 0 if everything worked out and < 0 if there were major errors.
1563  */
1564 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1565                            *root, struct btrfs_path *path, int data_size,
1566                            int empty)
1567 {
1568         struct extent_buffer *left = path->nodes[0];
1569         struct extent_buffer *right;
1570         struct extent_buffer *upper;
1571         struct btrfs_disk_key disk_key;
1572         int slot;
1573         u32 i;
1574         int free_space;
1575         int push_space = 0;
1576         int push_items = 0;
1577         struct btrfs_item *item;
1578         u32 left_nritems;
1579         u32 nr;
1580         u32 right_nritems;
1581         u32 data_end;
1582         u32 this_item_size;
1583         int ret;
1584
1585         slot = path->slots[1];
1586         if (!path->nodes[1]) {
1587                 return 1;
1588         }
1589         upper = path->nodes[1];
1590         if (slot >= btrfs_header_nritems(upper) - 1)
1591                 return 1;
1592
1593         right = read_tree_block(root, btrfs_node_blockptr(upper, slot + 1),
1594                                 root->leafsize);
1595         free_space = btrfs_leaf_free_space(root, right);
1596         if (free_space < data_size + sizeof(struct btrfs_item)) {
1597                 free_extent_buffer(right);
1598                 return 1;
1599         }
1600
1601         /* cow and double check */
1602         ret = btrfs_cow_block(trans, root, right, upper,
1603                               slot + 1, &right);
1604         if (ret) {
1605                 free_extent_buffer(right);
1606                 return 1;
1607         }
1608         free_space = btrfs_leaf_free_space(root, right);
1609         if (free_space < data_size + sizeof(struct btrfs_item)) {
1610                 free_extent_buffer(right);
1611                 return 1;
1612         }
1613
1614         left_nritems = btrfs_header_nritems(left);
1615         if (left_nritems == 0) {
1616                 free_extent_buffer(right);
1617                 return 1;
1618         }
1619
1620         if (empty)
1621                 nr = 0;
1622         else
1623                 nr = 1;
1624
1625         i = left_nritems - 1;
1626         while (i >= nr) {
1627                 item = btrfs_item_nr(left, i);
1628
1629                 if (path->slots[0] == i)
1630                         push_space += data_size + sizeof(*item);
1631
1632                 this_item_size = btrfs_item_size(left, item);
1633                 if (this_item_size + sizeof(*item) + push_space > free_space)
1634                         break;
1635                 push_items++;
1636                 push_space += this_item_size + sizeof(*item);
1637                 if (i == 0)
1638                         break;
1639                 i--;
1640         }
1641
1642         if (push_items == 0) {
1643                 free_extent_buffer(right);
1644                 return 1;
1645         }
1646
1647         if (!empty && push_items == left_nritems)
1648                 WARN_ON(1);
1649
1650         /* push left to right */
1651         right_nritems = btrfs_header_nritems(right);
1652
1653         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1654         push_space -= leaf_data_end(root, left);
1655
1656         /* make room in the right data area */
1657         data_end = leaf_data_end(root, right);
1658         memmove_extent_buffer(right,
1659                               btrfs_leaf_data(right) + data_end - push_space,
1660                               btrfs_leaf_data(right) + data_end,
1661                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1662
1663         /* copy from the left data area */
1664         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1665                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1666                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1667                      push_space);
1668
1669         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1670                               btrfs_item_nr_offset(0),
1671                               right_nritems * sizeof(struct btrfs_item));
1672
1673         /* copy the items from left to right */
1674         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1675                    btrfs_item_nr_offset(left_nritems - push_items),
1676                    push_items * sizeof(struct btrfs_item));
1677
1678         /* update the item pointers */
1679         right_nritems += push_items;
1680         btrfs_set_header_nritems(right, right_nritems);
1681         push_space = BTRFS_LEAF_DATA_SIZE(root);
1682         for (i = 0; i < right_nritems; i++) {
1683                 item = btrfs_item_nr(right, i);
1684                 push_space -= btrfs_item_size(right, item);
1685                 btrfs_set_item_offset(right, item, push_space);
1686         }
1687
1688         left_nritems -= push_items;
1689         btrfs_set_header_nritems(left, left_nritems);
1690
1691         if (left_nritems)
1692                 btrfs_mark_buffer_dirty(left);
1693         btrfs_mark_buffer_dirty(right);
1694
1695         btrfs_item_key(right, &disk_key, 0);
1696         btrfs_set_node_key(upper, &disk_key, slot + 1);
1697         btrfs_mark_buffer_dirty(upper);
1698
1699         /* then fixup the leaf pointer in the path */
1700         if (path->slots[0] >= left_nritems) {
1701                 path->slots[0] -= left_nritems;
1702                 free_extent_buffer(path->nodes[0]);
1703                 path->nodes[0] = right;
1704                 path->slots[1] += 1;
1705         } else {
1706                 free_extent_buffer(right);
1707         }
1708         return 0;
1709 }
1710 /*
1711  * push some data in the path leaf to the left, trying to free up at
1712  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1713  */
1714 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1715                           *root, struct btrfs_path *path, int data_size,
1716                           int empty)
1717 {
1718         struct btrfs_disk_key disk_key;
1719         struct extent_buffer *right = path->nodes[0];
1720         struct extent_buffer *left;
1721         int slot;
1722         int i;
1723         int free_space;
1724         int push_space = 0;
1725         int push_items = 0;
1726         struct btrfs_item *item;
1727         u32 old_left_nritems;
1728         u32 right_nritems;
1729         u32 nr;
1730         int ret = 0;
1731         int wret;
1732         u32 this_item_size;
1733         u32 old_left_item_size;
1734
1735         slot = path->slots[1];
1736         if (slot == 0)
1737                 return 1;
1738         if (!path->nodes[1])
1739                 return 1;
1740
1741         right_nritems = btrfs_header_nritems(right);
1742         if (right_nritems == 0) {
1743                 return 1;
1744         }
1745
1746         left = read_tree_block(root, btrfs_node_blockptr(path->nodes[1],
1747                                slot - 1), root->leafsize);
1748         free_space = btrfs_leaf_free_space(root, left);
1749         if (free_space < data_size + sizeof(struct btrfs_item)) {
1750                 free_extent_buffer(left);
1751                 return 1;
1752         }
1753
1754         /* cow and double check */
1755         ret = btrfs_cow_block(trans, root, left,
1756                               path->nodes[1], slot - 1, &left);
1757         if (ret) {
1758                 /* we hit -ENOSPC, but it isn't fatal here */
1759                 free_extent_buffer(left);
1760                 return 1;
1761         }
1762
1763         free_space = btrfs_leaf_free_space(root, left);
1764         if (free_space < data_size + sizeof(struct btrfs_item)) {
1765                 free_extent_buffer(left);
1766                 return 1;
1767         }
1768
1769         if (empty)
1770                 nr = right_nritems;
1771         else
1772                 nr = right_nritems - 1;
1773
1774         for (i = 0; i < nr; i++) {
1775                 item = btrfs_item_nr(right, i);
1776
1777                 if (path->slots[0] == i)
1778                         push_space += data_size + sizeof(*item);
1779
1780                 this_item_size = btrfs_item_size(right, item);
1781                 if (this_item_size + sizeof(*item) + push_space > free_space)
1782                         break;
1783
1784                 push_items++;
1785                 push_space += this_item_size + sizeof(*item);
1786         }
1787
1788         if (push_items == 0) {
1789                 free_extent_buffer(left);
1790                 return 1;
1791         }
1792         if (!empty && push_items == btrfs_header_nritems(right))
1793                 WARN_ON(1);
1794
1795         /* push data from right to left */
1796         copy_extent_buffer(left, right,
1797                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1798                            btrfs_item_nr_offset(0),
1799                            push_items * sizeof(struct btrfs_item));
1800
1801         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1802                      btrfs_item_offset_nr(right, push_items -1);
1803
1804         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1805                      leaf_data_end(root, left) - push_space,
1806                      btrfs_leaf_data(right) +
1807                      btrfs_item_offset_nr(right, push_items - 1),
1808                      push_space);
1809         old_left_nritems = btrfs_header_nritems(left);
1810         BUG_ON(old_left_nritems < 0);
1811
1812         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
1813         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1814                 u32 ioff;
1815
1816                 item = btrfs_item_nr(left, i);
1817                 ioff = btrfs_item_offset(left, item);
1818                 btrfs_set_item_offset(left, item,
1819                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
1820         }
1821         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1822
1823         /* fixup right node */
1824         if (push_items > right_nritems) {
1825                 printk("push items %d nr %u\n", push_items, right_nritems);
1826                 WARN_ON(1);
1827         }
1828
1829         if (push_items < right_nritems) {
1830                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
1831                                                   leaf_data_end(root, right);
1832                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
1833                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
1834                                       btrfs_leaf_data(right) +
1835                                       leaf_data_end(root, right), push_space);
1836
1837                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1838                               btrfs_item_nr_offset(push_items),
1839                              (btrfs_header_nritems(right) - push_items) *
1840                              sizeof(struct btrfs_item));
1841         }
1842         right_nritems -= push_items;
1843         btrfs_set_header_nritems(right, right_nritems);
1844         push_space = BTRFS_LEAF_DATA_SIZE(root);
1845         for (i = 0; i < right_nritems; i++) {
1846                 item = btrfs_item_nr(right, i);
1847                 push_space = push_space - btrfs_item_size(right, item);
1848                 btrfs_set_item_offset(right, item, push_space);
1849         }
1850
1851         btrfs_mark_buffer_dirty(left);
1852         if (right_nritems)
1853                 btrfs_mark_buffer_dirty(right);
1854
1855         btrfs_item_key(right, &disk_key, 0);
1856         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1857         if (wret)
1858                 ret = wret;
1859
1860         /* then fixup the leaf pointer in the path */
1861         if (path->slots[0] < push_items) {
1862                 path->slots[0] += old_left_nritems;
1863                 free_extent_buffer(path->nodes[0]);
1864                 path->nodes[0] = left;
1865                 path->slots[1] -= 1;
1866         } else {
1867                 free_extent_buffer(left);
1868                 path->slots[0] -= push_items;
1869         }
1870         BUG_ON(path->slots[0] < 0);
1871         return ret;
1872 }
1873
1874 /*
1875  * split the path's leaf in two, making sure there is at least data_size
1876  * available for the resulting leaf level of the path.
1877  *
1878  * returns 0 if all went well and < 0 on failure.
1879  */
1880 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1881                       *root, struct btrfs_key *ins_key,
1882                       struct btrfs_path *path, int data_size, int extend)
1883 {
1884         u64 root_gen;
1885         struct extent_buffer *l;
1886         u32 nritems;
1887         int mid;
1888         int slot;
1889         struct extent_buffer *right;
1890         int space_needed = data_size + sizeof(struct btrfs_item);
1891         int data_copy_size;
1892         int rt_data_off;
1893         int i;
1894         int ret = 0;
1895         int wret;
1896         int double_split;
1897         int num_doubles = 0;
1898         struct btrfs_disk_key disk_key;
1899
1900         if (extend)
1901                 space_needed = data_size;
1902
1903         if (root->ref_cows)
1904                 root_gen = trans->transid;
1905         else
1906                 root_gen = 0;
1907
1908         /* first try to make some room by pushing left and right */
1909         if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
1910                 wret = push_leaf_right(trans, root, path, data_size, 0);
1911                 if (wret < 0) {
1912                         return wret;
1913                 }
1914                 if (wret) {
1915                         wret = push_leaf_left(trans, root, path, data_size, 0);
1916                         if (wret < 0)
1917                                 return wret;
1918                 }
1919                 l = path->nodes[0];
1920
1921                 /* did the pushes work? */
1922                 if (btrfs_leaf_free_space(root, l) >= space_needed)
1923                         return 0;
1924         }
1925
1926         if (!path->nodes[1]) {
1927                 ret = insert_new_root(trans, root, path, 1);
1928                 if (ret)
1929                         return ret;
1930         }
1931 again:
1932         double_split = 0;
1933         l = path->nodes[0];
1934         slot = path->slots[0];
1935         nritems = btrfs_header_nritems(l);
1936         mid = (nritems + 1)/ 2;
1937
1938         btrfs_item_key(l, &disk_key, 0);
1939
1940         right = __btrfs_alloc_free_block(trans, root, root->leafsize,
1941                                          root->root_key.objectid,
1942                                          root_gen, disk_key.objectid, 0,
1943                                          l->start, 0);
1944         if (IS_ERR(right)) {
1945                 BUG_ON(1);
1946                 return PTR_ERR(right);
1947         }
1948
1949         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1950         btrfs_set_header_bytenr(right, right->start);
1951         btrfs_set_header_generation(right, trans->transid);
1952         btrfs_set_header_owner(right, root->root_key.objectid);
1953         btrfs_set_header_level(right, 0);
1954         write_extent_buffer(right, root->fs_info->fsid,
1955                             (unsigned long)btrfs_header_fsid(right),
1956                             BTRFS_FSID_SIZE);
1957
1958         write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
1959                             (unsigned long)btrfs_header_chunk_tree_uuid(right),
1960                             BTRFS_UUID_SIZE);
1961         if (mid <= slot) {
1962                 if (nritems == 1 ||
1963                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1964                         BTRFS_LEAF_DATA_SIZE(root)) {
1965                         if (slot >= nritems) {
1966                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1967                                 btrfs_set_header_nritems(right, 0);
1968                                 wret = insert_ptr(trans, root, path,
1969                                                   &disk_key, right->start,
1970                                                   path->slots[1] + 1, 1);
1971                                 if (wret)
1972                                         ret = wret;
1973                                 free_extent_buffer(path->nodes[0]);
1974                                 path->nodes[0] = right;
1975                                 path->slots[0] = 0;
1976                                 path->slots[1] += 1;
1977                                 return ret;
1978                         }
1979                         mid = slot;
1980                         if (mid != nritems &&
1981                             leaf_space_used(l, mid, nritems - mid) +
1982                             space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1983                                 double_split = 1;
1984                         }
1985                 }
1986         } else {
1987                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1988                         BTRFS_LEAF_DATA_SIZE(root)) {
1989                         if (!extend && slot == 0) {
1990                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1991                                 btrfs_set_header_nritems(right, 0);
1992                                 wret = insert_ptr(trans, root, path,
1993                                                   &disk_key,
1994                                                   right->start,
1995                                                   path->slots[1], 1);
1996                                 if (wret)
1997                                         ret = wret;
1998                                 free_extent_buffer(path->nodes[0]);
1999                                 path->nodes[0] = right;
2000                                 path->slots[0] = 0;
2001                                 if (path->slots[1] == 0) {
2002                                         wret = fixup_low_keys(trans, root,
2003                                                    path, &disk_key, 1);
2004                                         if (wret)
2005                                                 ret = wret;
2006                                 }
2007                                 return ret;
2008                         } else if (extend && slot == 0) {
2009                                 mid = 1;
2010                         } else {
2011                                 mid = slot;
2012                                 if (mid != nritems &&
2013                                     leaf_space_used(l, mid, nritems - mid) +
2014                                     space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
2015                                         double_split = 1;
2016                                 }
2017                         }
2018                 }
2019         }
2020         nritems = nritems - mid;
2021         btrfs_set_header_nritems(right, nritems);
2022         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
2023
2024         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2025                            btrfs_item_nr_offset(mid),
2026                            nritems * sizeof(struct btrfs_item));
2027
2028         copy_extent_buffer(right, l,
2029                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2030                      data_copy_size, btrfs_leaf_data(l) +
2031                      leaf_data_end(root, l), data_copy_size);
2032
2033         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2034                       btrfs_item_end_nr(l, mid);
2035
2036         for (i = 0; i < nritems; i++) {
2037                 struct btrfs_item *item = btrfs_item_nr(right, i);
2038                 u32 ioff = btrfs_item_offset(right, item);
2039                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2040         }
2041
2042         btrfs_set_header_nritems(l, mid);
2043         ret = 0;
2044         btrfs_item_key(right, &disk_key, 0);
2045         wret = insert_ptr(trans, root, path, &disk_key, right->start,
2046                           path->slots[1] + 1, 1);
2047         if (wret)
2048                 ret = wret;
2049
2050         btrfs_mark_buffer_dirty(right);
2051         btrfs_mark_buffer_dirty(l);
2052         BUG_ON(path->slots[0] != slot);
2053
2054         if (mid <= slot) {
2055                 free_extent_buffer(path->nodes[0]);
2056                 path->nodes[0] = right;
2057                 path->slots[0] -= mid;
2058                 path->slots[1] += 1;
2059         } else
2060                 free_extent_buffer(right);
2061
2062         BUG_ON(path->slots[0] < 0);
2063
2064         if (double_split) {
2065                 BUG_ON(num_doubles != 0);
2066                 num_doubles++;
2067                 goto again;
2068         }
2069         return ret;
2070 }
2071
2072 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
2073                         struct btrfs_root *root,
2074                         struct btrfs_path *path,
2075                         u32 new_size, int from_end)
2076 {
2077         int ret = 0;
2078         int slot;
2079         int slot_orig;
2080         struct extent_buffer *leaf;
2081         struct btrfs_item *item;
2082         u32 nritems;
2083         unsigned int data_end;
2084         unsigned int old_data_start;
2085         unsigned int old_size;
2086         unsigned int size_diff;
2087         int i;
2088
2089         slot_orig = path->slots[0];
2090         leaf = path->nodes[0];
2091         slot = path->slots[0];
2092
2093         old_size = btrfs_item_size_nr(leaf, slot);
2094         if (old_size == new_size)
2095                 return 0;
2096
2097         nritems = btrfs_header_nritems(leaf);
2098         data_end = leaf_data_end(root, leaf);
2099
2100         old_data_start = btrfs_item_offset_nr(leaf, slot);
2101
2102         size_diff = old_size - new_size;
2103
2104         BUG_ON(slot < 0);
2105         BUG_ON(slot >= nritems);
2106
2107         /*
2108          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2109          */
2110         /* first correct the data pointers */
2111         for (i = slot; i < nritems; i++) {
2112                 u32 ioff;
2113                 item = btrfs_item_nr(leaf, i);
2114                 ioff = btrfs_item_offset(leaf, item);
2115                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2116         }
2117
2118         /* shift the data */
2119         if (from_end) {
2120                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2121                               data_end + size_diff, btrfs_leaf_data(leaf) +
2122                               data_end, old_data_start + new_size - data_end);
2123         } else {
2124                 struct btrfs_disk_key disk_key;
2125                 u64 offset;
2126
2127                 btrfs_item_key(leaf, &disk_key, slot);
2128
2129                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
2130                         unsigned long ptr;
2131                         struct btrfs_file_extent_item *fi;
2132
2133                         fi = btrfs_item_ptr(leaf, slot,
2134                                             struct btrfs_file_extent_item);
2135                         fi = (struct btrfs_file_extent_item *)(
2136                              (unsigned long)fi - size_diff);
2137
2138                         if (btrfs_file_extent_type(leaf, fi) ==
2139                             BTRFS_FILE_EXTENT_INLINE) {
2140                                 ptr = btrfs_item_ptr_offset(leaf, slot);
2141                                 memmove_extent_buffer(leaf, ptr,
2142                                         (unsigned long)fi,
2143                                         offsetof(struct btrfs_file_extent_item,
2144                                                  disk_bytenr));
2145                         }
2146                 }
2147
2148                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2149                               data_end + size_diff, btrfs_leaf_data(leaf) +
2150                               data_end, old_data_start - data_end);
2151
2152                 offset = btrfs_disk_key_offset(&disk_key);
2153                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
2154                 btrfs_set_item_key(leaf, &disk_key, slot);
2155                 if (slot == 0)
2156                         fixup_low_keys(trans, root, path, &disk_key, 1);
2157         }
2158
2159         item = btrfs_item_nr(leaf, slot);
2160         btrfs_set_item_size(leaf, item, new_size);
2161         btrfs_mark_buffer_dirty(leaf);
2162
2163         ret = 0;
2164         if (btrfs_leaf_free_space(root, leaf) < 0) {
2165                 btrfs_print_leaf(root, leaf);
2166                 BUG();
2167         }
2168         return ret;
2169 }
2170
2171 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2172                       struct btrfs_root *root, struct btrfs_path *path,
2173                       u32 data_size)
2174 {
2175         int ret = 0;
2176         int slot;
2177         int slot_orig;
2178         struct extent_buffer *leaf;
2179         struct btrfs_item *item;
2180         u32 nritems;
2181         unsigned int data_end;
2182         unsigned int old_data;
2183         unsigned int old_size;
2184         int i;
2185
2186         slot_orig = path->slots[0];
2187         leaf = path->nodes[0];
2188
2189         nritems = btrfs_header_nritems(leaf);
2190         data_end = leaf_data_end(root, leaf);
2191
2192         if (btrfs_leaf_free_space(root, leaf) < data_size) {
2193                 btrfs_print_leaf(root, leaf);
2194                 BUG();
2195         }
2196         slot = path->slots[0];
2197         old_data = btrfs_item_end_nr(leaf, slot);
2198
2199         BUG_ON(slot < 0);
2200         if (slot >= nritems) {
2201                 btrfs_print_leaf(root, leaf);
2202                 printk("slot %d too large, nritems %d\n", slot, nritems);
2203                 BUG_ON(1);
2204         }
2205
2206         /*
2207          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2208          */
2209         /* first correct the data pointers */
2210         for (i = slot; i < nritems; i++) {
2211                 u32 ioff;
2212                 item = btrfs_item_nr(leaf, i);
2213                 ioff = btrfs_item_offset(leaf, item);
2214                 btrfs_set_item_offset(leaf, item, ioff - data_size);
2215         }
2216
2217         /* shift the data */
2218         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2219                       data_end - data_size, btrfs_leaf_data(leaf) +
2220                       data_end, old_data - data_end);
2221
2222         data_end = old_data;
2223         old_size = btrfs_item_size_nr(leaf, slot);
2224         item = btrfs_item_nr(leaf, slot);
2225         btrfs_set_item_size(leaf, item, old_size + data_size);
2226         btrfs_mark_buffer_dirty(leaf);
2227
2228         ret = 0;
2229         if (btrfs_leaf_free_space(root, leaf) < 0) {
2230                 btrfs_print_leaf(root, leaf);
2231                 BUG();
2232         }
2233         return ret;
2234 }
2235
2236 /*
2237  * Given a key and some data, insert an item into the tree.
2238  * This does all the path init required, making room in the tree if needed.
2239  */
2240 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
2241                             struct btrfs_root *root,
2242                             struct btrfs_path *path,
2243                             struct btrfs_key *cpu_key, u32 *data_size,
2244                             int nr)
2245 {
2246         struct extent_buffer *leaf;
2247         struct btrfs_item *item;
2248         int ret = 0;
2249         int slot;
2250         int slot_orig;
2251         int i;
2252         u32 nritems;
2253         u32 total_size = 0;
2254         u32 total_data = 0;
2255         unsigned int data_end;
2256         struct btrfs_disk_key disk_key;
2257
2258         for (i = 0; i < nr; i++) {
2259                 total_data += data_size[i];
2260         }
2261
2262         /* create a root if there isn't one */
2263         if (!root->node)
2264                 BUG();
2265
2266         total_size = total_data + (nr - 1) * sizeof(struct btrfs_item);
2267         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
2268         if (ret == 0) {
2269                 return -EEXIST;
2270         }
2271         if (ret < 0)
2272                 goto out;
2273
2274         slot_orig = path->slots[0];
2275         leaf = path->nodes[0];
2276
2277         nritems = btrfs_header_nritems(leaf);
2278         data_end = leaf_data_end(root, leaf);
2279
2280         if (btrfs_leaf_free_space(root, leaf) <
2281             sizeof(struct btrfs_item) + total_size) {
2282                 btrfs_print_leaf(root, leaf);
2283                 printk("not enough freespace need %u have %d\n",
2284                        total_size, btrfs_leaf_free_space(root, leaf));
2285                 BUG();
2286         }
2287
2288         slot = path->slots[0];
2289         BUG_ON(slot < 0);
2290
2291         if (slot != nritems) {
2292                 int i;
2293                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2294
2295                 if (old_data < data_end) {
2296                         btrfs_print_leaf(root, leaf);
2297                         printk("slot %d old_data %d data_end %d\n",
2298                                slot, old_data, data_end);
2299                         BUG_ON(1);
2300                 }
2301                 /*
2302                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2303                  */
2304                 /* first correct the data pointers */
2305                 for (i = slot; i < nritems; i++) {
2306                         u32 ioff;
2307
2308                         item = btrfs_item_nr(leaf, i);
2309                         ioff = btrfs_item_offset(leaf, item);
2310                         btrfs_set_item_offset(leaf, item, ioff - total_data);
2311                 }
2312
2313                 /* shift the items */
2314                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
2315                               btrfs_item_nr_offset(slot),
2316                               (nritems - slot) * sizeof(struct btrfs_item));
2317
2318                 /* shift the data */
2319                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2320                               data_end - total_data, btrfs_leaf_data(leaf) +
2321                               data_end, old_data - data_end);
2322                 data_end = old_data;
2323         }
2324
2325         /* setup the item for the new data */
2326         for (i = 0; i < nr; i++) {
2327                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
2328                 btrfs_set_item_key(leaf, &disk_key, slot + i);
2329                 item = btrfs_item_nr(leaf, slot + i);
2330                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
2331                 data_end -= data_size[i];
2332                 btrfs_set_item_size(leaf, item, data_size[i]);
2333         }
2334         btrfs_set_header_nritems(leaf, nritems + nr);
2335         btrfs_mark_buffer_dirty(leaf);
2336
2337         ret = 0;
2338         if (slot == 0) {
2339                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2340                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2341         }
2342
2343         if (btrfs_leaf_free_space(root, leaf) < 0) {
2344                 btrfs_print_leaf(root, leaf);
2345                 BUG();
2346         }
2347
2348 out:
2349         return ret;
2350 }
2351
2352 /*
2353  * Given a key and some data, insert an item into the tree.
2354  * This does all the path init required, making room in the tree if needed.
2355  */
2356 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2357                       *root, struct btrfs_key *cpu_key, void *data, u32
2358                       data_size)
2359 {
2360         int ret = 0;
2361         struct btrfs_path *path;
2362         struct extent_buffer *leaf;
2363         unsigned long ptr;
2364
2365         path = btrfs_alloc_path();
2366         BUG_ON(!path);
2367         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2368         if (!ret) {
2369                 leaf = path->nodes[0];
2370                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2371                 write_extent_buffer(leaf, data, ptr, data_size);
2372                 btrfs_mark_buffer_dirty(leaf);
2373         }
2374         btrfs_free_path(path);
2375         return ret;
2376 }
2377
2378 /*
2379  * delete the pointer from a given node.
2380  *
2381  * If the delete empties a node, the node is removed from the tree,
2382  * continuing all the way the root if required.  The root is converted into
2383  * a leaf if all the nodes are emptied.
2384  */
2385 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2386                    struct btrfs_path *path, int level, int slot)
2387 {
2388         struct extent_buffer *parent = path->nodes[level];
2389         u32 nritems;
2390         int ret = 0;
2391         int wret;
2392
2393         nritems = btrfs_header_nritems(parent);
2394         if (slot != nritems -1) {
2395                 memmove_extent_buffer(parent,
2396                               btrfs_node_key_ptr_offset(slot),
2397                               btrfs_node_key_ptr_offset(slot + 1),
2398                               sizeof(struct btrfs_key_ptr) *
2399                               (nritems - slot - 1));
2400         }
2401         nritems--;
2402         btrfs_set_header_nritems(parent, nritems);
2403         if (nritems == 0 && parent == root->node) {
2404                 BUG_ON(btrfs_header_level(root->node) != 1);
2405                 /* just turn the root into a leaf and break */
2406                 btrfs_set_header_level(root->node, 0);
2407         } else if (slot == 0) {
2408                 struct btrfs_disk_key disk_key;
2409
2410                 btrfs_node_key(parent, &disk_key, 0);
2411                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2412                 if (wret)
2413                         ret = wret;
2414         }
2415         btrfs_mark_buffer_dirty(parent);
2416         return ret;
2417 }
2418
2419 /*
2420  * delete the item at the leaf level in path.  If that empties
2421  * the leaf, remove it from the tree
2422  */
2423 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2424                     struct btrfs_path *path, int slot, int nr)
2425 {
2426         struct extent_buffer *leaf;
2427         struct btrfs_item *item;
2428         int last_off;
2429         int dsize = 0;
2430         int ret = 0;
2431         int wret;
2432         int i;
2433         u32 nritems;
2434
2435         leaf = path->nodes[0];
2436         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
2437
2438         for (i = 0; i < nr; i++)
2439                 dsize += btrfs_item_size_nr(leaf, slot + i);
2440
2441         nritems = btrfs_header_nritems(leaf);
2442
2443         if (slot + nr != nritems) {
2444                 int i;
2445                 int data_end = leaf_data_end(root, leaf);
2446
2447                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2448                               data_end + dsize,
2449                               btrfs_leaf_data(leaf) + data_end,
2450                               last_off - data_end);
2451
2452                 for (i = slot + nr; i < nritems; i++) {
2453                         u32 ioff;
2454
2455                         item = btrfs_item_nr(leaf, i);
2456                         ioff = btrfs_item_offset(leaf, item);
2457                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2458                 }
2459
2460                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2461                               btrfs_item_nr_offset(slot + nr),
2462                               sizeof(struct btrfs_item) *
2463                               (nritems - slot - nr));
2464         }
2465         btrfs_set_header_nritems(leaf, nritems - nr);
2466         nritems -= nr;
2467
2468         /* delete the leaf if we've emptied it */
2469         if (nritems == 0) {
2470                 if (leaf == root->node) {
2471                         btrfs_set_header_level(leaf, 0);
2472                 } else {
2473                         u64 root_gen = btrfs_header_generation(path->nodes[1]);
2474                         clean_tree_block(trans, root, leaf);
2475                         wait_on_tree_block_writeback(root, leaf);
2476                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
2477                         if (wret)
2478                                 ret = wret;
2479                         wret = btrfs_free_extent(trans, root,
2480                                          leaf->start, leaf->len,
2481                                          btrfs_header_owner(path->nodes[1]),
2482                                          root_gen, 0, 0, 1);
2483                         if (wret)
2484                                 ret = wret;
2485                 }
2486         } else {
2487                 int used = leaf_space_used(leaf, 0, nritems);
2488                 if (slot == 0) {
2489                         struct btrfs_disk_key disk_key;
2490
2491                         btrfs_item_key(leaf, &disk_key, 0);
2492                         wret = fixup_low_keys(trans, root, path,
2493                                               &disk_key, 1);
2494                         if (wret)
2495                                 ret = wret;
2496                 }
2497
2498                 /* delete the leaf if it is mostly empty */
2499                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 4) {
2500                         /* push_leaf_left fixes the path.
2501                          * make sure the path still points to our leaf
2502                          * for possible call to del_ptr below
2503                          */
2504                         slot = path->slots[1];
2505                         extent_buffer_get(leaf);
2506
2507                         wret = push_leaf_left(trans, root, path, 1, 1);
2508                         if (wret < 0 && wret != -ENOSPC)
2509                                 ret = wret;
2510
2511                         if (path->nodes[0] == leaf &&
2512                             btrfs_header_nritems(leaf)) {
2513                                 wret = push_leaf_right(trans, root, path, 1, 1);
2514                                 if (wret < 0 && wret != -ENOSPC)
2515                                         ret = wret;
2516                         }
2517
2518                         if (btrfs_header_nritems(leaf) == 0) {
2519                                 u64 root_gen;
2520                                 u64 bytenr = leaf->start;
2521                                 u32 blocksize = leaf->len;
2522
2523                                 root_gen = btrfs_header_generation(
2524                                                            path->nodes[1]);
2525
2526                                 clean_tree_block(trans, root, leaf);
2527                                 wait_on_tree_block_writeback(root, leaf);
2528
2529                                 wret = del_ptr(trans, root, path, 1, slot);
2530                                 if (wret)
2531                                         ret = wret;
2532
2533                                 free_extent_buffer(leaf);
2534                                 wret = btrfs_free_extent(trans, root, bytenr,
2535                                              blocksize,
2536                                              btrfs_header_owner(path->nodes[1]),
2537                                              root_gen, 0, 0, 1);
2538                                 if (wret)
2539                                         ret = wret;
2540                         } else {
2541                                 btrfs_mark_buffer_dirty(leaf);
2542                                 free_extent_buffer(leaf);
2543                         }
2544                 } else {
2545                         btrfs_mark_buffer_dirty(leaf);
2546                 }
2547         }
2548         return ret;
2549 }
2550
2551 /*
2552  * walk up the tree as far as required to find the previous leaf.
2553  * returns 0 if it found something or 1 if there are no lesser leaves.
2554  * returns < 0 on io errors.
2555  */
2556 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2557 {
2558         u64 bytenr;
2559         int slot;
2560         int level = 1;
2561         struct extent_buffer *c;
2562         struct extent_buffer *next = NULL;
2563
2564         while(level < BTRFS_MAX_LEVEL) {
2565                 if (!path->nodes[level])
2566                         return 1;
2567
2568                 slot = path->slots[level];
2569                 c = path->nodes[level];
2570                 if (slot == 0) {
2571                         level++;
2572                         if (level == BTRFS_MAX_LEVEL)
2573                                 return 1;
2574                         continue;
2575                 }
2576                 slot--;
2577
2578                 bytenr = btrfs_node_blockptr(c, slot);
2579                 if (next)
2580                         free_extent_buffer(next);
2581
2582                 next = read_tree_block(root, bytenr,
2583                                        btrfs_level_size(root, level - 1));
2584                 break;
2585         }
2586         path->slots[level] = slot;
2587         while(1) {
2588                 level--;
2589                 c = path->nodes[level];
2590                 free_extent_buffer(c);
2591                 slot = btrfs_header_nritems(next);
2592                 if (slot != 0)
2593                         slot--;
2594                 path->nodes[level] = next;
2595                 path->slots[level] = slot;
2596                 if (!level)
2597                         break;
2598                 next = read_tree_block(root, btrfs_node_blockptr(next, slot),
2599                                        btrfs_level_size(root, level - 1));
2600         }
2601         return 0;
2602 }
2603
2604 /*
2605  * walk up the tree as far as required to find the next leaf.
2606  * returns 0 if it found something or 1 if there are no greater leaves.
2607  * returns < 0 on io errors.
2608  */
2609 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2610 {
2611         int slot;
2612         int level = 1;
2613         u64 bytenr;
2614         struct extent_buffer *c;
2615         struct extent_buffer *next = NULL;
2616
2617         while(level < BTRFS_MAX_LEVEL) {
2618                 if (!path->nodes[level])
2619                         return 1;
2620
2621                 slot = path->slots[level] + 1;
2622                 c = path->nodes[level];
2623                 if (slot >= btrfs_header_nritems(c)) {
2624                         level++;
2625                         if (level == BTRFS_MAX_LEVEL)
2626                                 return 1;
2627                         continue;
2628                 }
2629
2630                 bytenr = btrfs_node_blockptr(c, slot);
2631                 if (next)
2632                         free_extent_buffer(next);
2633
2634                 if (path->reada)
2635                         reada_for_search(root, path, level, slot, 0);
2636
2637                 next = read_tree_block(root, bytenr,
2638                                        btrfs_level_size(root, level -1));
2639                 break;
2640         }
2641         path->slots[level] = slot;
2642         while(1) {
2643                 level--;
2644                 c = path->nodes[level];
2645                 free_extent_buffer(c);
2646                 path->nodes[level] = next;
2647                 path->slots[level] = 0;
2648                 if (!level)
2649                         break;
2650                 if (path->reada)
2651                         reada_for_search(root, path, level, 0, 0);
2652                 next = read_tree_block(root, btrfs_node_blockptr(next, 0),
2653                                        btrfs_level_size(root, level - 1));
2654         }
2655         return 0;
2656 }
2657
2658 int btrfs_previous_item(struct btrfs_root *root,
2659                         struct btrfs_path *path, u64 min_objectid,
2660                         int type)
2661 {
2662         struct btrfs_key found_key;
2663         struct extent_buffer *leaf;
2664         int ret;
2665
2666         while(1) {
2667                 if (path->slots[0] == 0) {
2668                         ret = btrfs_prev_leaf(root, path);
2669                         if (ret != 0)
2670                                 return ret;
2671                 } else {
2672                         path->slots[0]--;
2673                 }
2674                 leaf = path->nodes[0];
2675                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2676                 if (found_key.type == type)
2677                         return 0;
2678         }
2679         return 1;
2680 }
2681