fs/btrfs/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
  19 #include <linux/sched.h>
  20 #include "ctree.h"
  21 #include "disk-io.h"
  22 #include "transaction.h"
  23 #include "print-tree.h"
  24 #include "locking.h"
  25
  26 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  27                       *root, struct btrfs_path *path, int level);
  28 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  29                       *root, struct btrfs_key *ins_key,
  30                       struct btrfs_path *path, int data_size, int extend);
  31 static int push_node_left(struct btrfs_trans_handle *trans,
  32                           struct btrfs_root *root, struct extent_buffer *dst,
  33                           struct extent_buffer *src, int empty);
  34 static int balance_node_right(struct btrfs_trans_handle *trans,
  35                               struct btrfs_root *root,
  36                               struct extent_buffer *dst_buf,
  37                               struct extent_buffer *src_buf);
  38 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  39                    struct btrfs_path *path, int level, int slot);
  40
  41 inline void btrfs_init_path(struct btrfs_path *p)
  42 {
  43         memset(p, 0, sizeof(*p));
  44 }
  45
  46 struct btrfs_path *btrfs_alloc_path(void)
  47 {
  48         struct btrfs_path *path;
  49         path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
  50         if (path) {
  51                 btrfs_init_path(path);
  52                 path->reada = 1;
  53         }
  54         return path;
  55 }
  56
  57 void btrfs_free_path(struct btrfs_path *p)
  58 {
  59         btrfs_release_path(NULL, p);
  60         kmem_cache_free(btrfs_path_cachep, p);
  61 }
  62
  63 void noinline btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
  64 {
  65         int i;
  66
  67         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  68                 p->slots[i] = 0;
  69                 if (!p->nodes[i])
  70                         continue;
  71                 if (p->locks[i]) {
  72                         btrfs_tree_unlock(p->nodes[i]);
  73                         p->locks[i] = 0;
  74                 }
  75                 free_extent_buffer(p->nodes[i]);
  76                 p->nodes[i] = NULL;
  77         }
  78 }
  79
  80 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
  81 {
  82         struct extent_buffer *eb;
  83         spin_lock(&root->node_lock);
  84         eb = root->node;
  85         extent_buffer_get(eb);
  86         spin_unlock(&root->node_lock);
  87         return eb;
  88 }
  89
  90 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
  91 {
  92         struct extent_buffer *eb;
  93
  94         while(1) {
  95                 eb = btrfs_root_node(root);
  96                 btrfs_tree_lock(eb);
  97
  98                 spin_lock(&root->node_lock);
  99                 if (eb == root->node) {
 100                         spin_unlock(&root->node_lock);
 101                         break;
 102                 }
 103                 spin_unlock(&root->node_lock);
 104
 105                 btrfs_tree_unlock(eb);
 106                 free_extent_buffer(eb);
 107         }
 108         return eb;
 109 }
 110
 111 static void add_root_to_dirty_list(struct btrfs_root *root)
 112 {
 113         if (root->track_dirty && list_empty(&root->dirty_list)) {
 114                 list_add(&root->dirty_list,
 115                          &root->fs_info->dirty_cowonly_roots);
 116         }
 117 }
 118
 119 int btrfs_copy_root(struct btrfs_trans_handle *trans,
 120                       struct btrfs_root *root,
 121                       struct extent_buffer *buf,
 122                       struct extent_buffer **cow_ret, u64 new_root_objectid)
 123 {
 124         struct extent_buffer *cow;
 125         u32 nritems;
 126         int ret = 0;
 127         int level;
 128         struct btrfs_key first_key;
 129         struct btrfs_root *new_root;
 130
 131         new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
 132         if (!new_root)
 133                 return -ENOMEM;
 134
 135         memcpy(new_root, root, sizeof(*new_root));
 136         new_root->root_key.objectid = new_root_objectid;
 137
 138         WARN_ON(root->ref_cows && trans->transid !=
 139                 root->fs_info->running_transaction->transid);
 140         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 141
 142         level = btrfs_header_level(buf);
 143         nritems = btrfs_header_nritems(buf);
 144         if (nritems) {
 145                 if (level == 0)
 146                         btrfs_item_key_to_cpu(buf, &first_key, 0);
 147                 else
 148                         btrfs_node_key_to_cpu(buf, &first_key, 0);
 149         } else {
 150                 first_key.objectid = 0;
 151         }
 152         cow = btrfs_alloc_free_block(trans, new_root, buf->len,
 153                                        new_root_objectid,
 154                                        trans->transid, first_key.objectid,
 155                                        level, buf->start, 0);
 156         if (IS_ERR(cow)) {
 157                 kfree(new_root);
 158                 return PTR_ERR(cow);
 159         }
 160
 161         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 162         btrfs_set_header_bytenr(cow, cow->start);
 163         btrfs_set_header_generation(cow, trans->transid);
 164         btrfs_set_header_owner(cow, new_root_objectid);
 165         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
 166
 167         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 168         ret = btrfs_inc_ref(trans, new_root, buf, 0);
 169         kfree(new_root);
 170
 171         if (ret)
 172                 return ret;
 173
 174         btrfs_mark_buffer_dirty(cow);
 175         *cow_ret = cow;
 176         return 0;
 177 }
 178
 179 int noinline __btrfs_cow_block(struct btrfs_trans_handle *trans,
 180                              struct btrfs_root *root,
 181                              struct extent_buffer *buf,
 182                              struct extent_buffer *parent, int parent_slot,
 183                              struct extent_buffer **cow_ret,
 184                              u64 search_start, u64 empty_size,
 185                              u64 prealloc_dest)
 186 {
 187         u64 root_gen;
 188         struct extent_buffer *cow;
 189         u32 nritems;
 190         int ret = 0;
 191         int different_trans = 0;
 192         int level;
 193         int unlock_orig = 0;
 194         struct btrfs_key first_key;
 195
 196         if (*cow_ret == buf)
 197                 unlock_orig = 1;
 198
 199         WARN_ON(!btrfs_tree_locked(buf));
 200
 201         if (root->ref_cows) {
 202                 root_gen = trans->transid;
 203         } else {
 204                 root_gen = 0;
 205         }
 206         WARN_ON(root->ref_cows && trans->transid !=
 207                 root->fs_info->running_transaction->transid);
 208         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 209
 210         level = btrfs_header_level(buf);
 211         nritems = btrfs_header_nritems(buf);
 212         if (nritems) {
 213                 if (level == 0)
 214                         btrfs_item_key_to_cpu(buf, &first_key, 0);
 215                 else
 216                         btrfs_node_key_to_cpu(buf, &first_key, 0);
 217         } else {
 218                 first_key.objectid = 0;
 219         }
 220         if (prealloc_dest) {
 221                 struct btrfs_key ins;
 222
 223                 ins.objectid = prealloc_dest;
 224                 ins.offset = buf->len;
 225                 ins.type = BTRFS_EXTENT_ITEM_KEY;
 226
 227                 ret = btrfs_alloc_reserved_extent(trans, root,
 228                                                   root->root_key.objectid,
 229                                                   root_gen, level,
 230                                                   first_key.objectid,
 231                                                   &ins);
 232                 BUG_ON(ret);
 233                 cow = btrfs_init_new_buffer(trans, root, prealloc_dest,
 234                                             buf->len);
 235         } else {
 236                 cow = btrfs_alloc_free_block(trans, root, buf->len,
 237                                              root->root_key.objectid,
 238                                              root_gen, first_key.objectid,
 239                                              level, search_start, empty_size);
 240         }
 241         if (IS_ERR(cow))
 242                 return PTR_ERR(cow);
 243
 244         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 245         btrfs_set_header_bytenr(cow, cow->start);
 246         btrfs_set_header_generation(cow, trans->transid);
 247         btrfs_set_header_owner(cow, root->root_key.objectid);
 248         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
 249
 250         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 251         if (btrfs_header_generation(buf) != trans->transid) {
 252                 different_trans = 1;
 253                 ret = btrfs_inc_ref(trans, root, buf, 1);
 254                 if (ret)
 255                         return ret;
 256         } else {
 257                 clean_tree_block(trans, root, buf);
 258         }
 259
 260         if (buf == root->node) {
 261                 WARN_ON(parent && parent != buf);
 262                 root_gen = btrfs_header_generation(buf);
 263
 264                 spin_lock(&root->node_lock);
 265                 root->node = cow;
 266                 extent_buffer_get(cow);
 267                 spin_unlock(&root->node_lock);
 268
 269                 if (buf != root->commit_root) {
 270                         btrfs_free_extent(trans, root, buf->start,
 271                                           buf->len, root->root_key.objectid,
 272                                           root_gen, 0, 0, 1);
 273                 }
 274                 free_extent_buffer(buf);
 275                 add_root_to_dirty_list(root);
 276         } else {
 277                 root_gen = btrfs_header_generation(parent);
 278                 btrfs_set_node_blockptr(parent, parent_slot,
 279                                         cow->start);
 280                 WARN_ON(trans->transid == 0);
 281                 btrfs_set_node_ptr_generation(parent, parent_slot,
 282                                               trans->transid);
 283                 btrfs_mark_buffer_dirty(parent);
 284                 WARN_ON(btrfs_header_generation(parent) != trans->transid);
 285                 btrfs_free_extent(trans, root, buf->start, buf->len,
 286                                   btrfs_header_owner(parent), root_gen,
 287                                   0, 0, 1);
 288         }
 289         if (unlock_orig)
 290                 btrfs_tree_unlock(buf);
 291         free_extent_buffer(buf);
 292         btrfs_mark_buffer_dirty(cow);
 293         *cow_ret = cow;
 294         return 0;
 295 }
 296
 297 int noinline btrfs_cow_block(struct btrfs_trans_handle *trans,
 298                     struct btrfs_root *root, struct extent_buffer *buf,
 299                     struct extent_buffer *parent, int parent_slot,
 300                     struct extent_buffer **cow_ret, u64 prealloc_dest)
 301 {
 302         u64 search_start;
 303         u64 header_trans;
 304         int ret;
 305
 306         if (trans->transaction != root->fs_info->running_transaction) {
 307                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 308                        root->fs_info->running_transaction->transid);
 309                 WARN_ON(1);
 310         }
 311         if (trans->transid != root->fs_info->generation) {
 312                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 313                        root->fs_info->generation);
 314                 WARN_ON(1);
 315         }
 316
 317         header_trans = btrfs_header_generation(buf);
 318         spin_lock(&root->fs_info->hash_lock);
 319         if (header_trans == trans->transid &&
 320             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
 321                 *cow_ret = buf;
 322                 spin_unlock(&root->fs_info->hash_lock);
 323                 WARN_ON(prealloc_dest);
 324                 return 0;
 325         }
 326         spin_unlock(&root->fs_info->hash_lock);
 327         search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
 328         ret = __btrfs_cow_block(trans, root, buf, parent,
 329                                  parent_slot, cow_ret, search_start, 0,
 330                                  prealloc_dest);
 331         return ret;
 332 }
 333
 334 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 335 {
 336         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 337                 return 1;
 338         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 339                 return 1;
 340         return 0;
 341 }
 342
 343 /*
 344  * compare two keys in a memcmp fashion
 345  */
 346 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 347 {
 348         struct btrfs_key k1;
 349
 350         btrfs_disk_key_to_cpu(&k1, disk);
 351
 352         if (k1.objectid > k2->objectid)
 353                 return 1;
 354         if (k1.objectid < k2->objectid)
 355                 return -1;
 356         if (k1.type > k2->type)
 357                 return 1;
 358         if (k1.type < k2->type)
 359                 return -1;
 360         if (k1.offset > k2->offset)
 361                 return 1;
 362         if (k1.offset < k2->offset)
 363                 return -1;
 364         return 0;
 365 }
 366
 367
 368 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 369                        struct btrfs_root *root, struct extent_buffer *parent,
 370                        int start_slot, int cache_only, u64 *last_ret,
 371                        struct btrfs_key *progress)
 372 {
 373         struct extent_buffer *cur;
 374         u64 blocknr;
 375         u64 gen;
 376         u64 search_start = *last_ret;
 377         u64 last_block = 0;
 378         u64 other;
 379         u32 parent_nritems;
 380         int end_slot;
 381         int i;
 382         int err = 0;
 383         int parent_level;
 384         int uptodate;
 385         u32 blocksize;
 386         int progress_passed = 0;
 387         struct btrfs_disk_key disk_key;
 388
 389         parent_level = btrfs_header_level(parent);
 390         if (cache_only && parent_level != 1)
 391                 return 0;
 392
 393         if (trans->transaction != root->fs_info->running_transaction) {
 394                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 395                        root->fs_info->running_transaction->transid);
 396                 WARN_ON(1);
 397         }
 398         if (trans->transid != root->fs_info->generation) {
 399                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 400                        root->fs_info->generation);
 401                 WARN_ON(1);
 402         }
 403
 404         parent_nritems = btrfs_header_nritems(parent);
 405         blocksize = btrfs_level_size(root, parent_level - 1);
 406         end_slot = parent_nritems;
 407
 408         if (parent_nritems == 1)
 409                 return 0;
 410
 411         for (i = start_slot; i < end_slot; i++) {
 412                 int close = 1;
 413
 414                 if (!parent->map_token) {
 415                         map_extent_buffer(parent,
 416                                         btrfs_node_key_ptr_offset(i),
 417                                         sizeof(struct btrfs_key_ptr),
 418                                         &parent->map_token, &parent->kaddr,
 419                                         &parent->map_start, &parent->map_len,
 420                                         KM_USER1);
 421                 }
 422                 btrfs_node_key(parent, &disk_key, i);
 423                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
 424                         continue;
 425
 426                 progress_passed = 1;
 427                 blocknr = btrfs_node_blockptr(parent, i);
 428                 gen = btrfs_node_ptr_generation(parent, i);
 429                 if (last_block == 0)
 430                         last_block = blocknr;
 431
 432                 if (i > 0) {
 433                         other = btrfs_node_blockptr(parent, i - 1);
 434                         close = close_blocks(blocknr, other, blocksize);
 435                 }
 436                 if (!close && i < end_slot - 2) {
 437                         other = btrfs_node_blockptr(parent, i + 1);
 438                         close = close_blocks(blocknr, other, blocksize);
 439                 }
 440                 if (close) {
 441                         last_block = blocknr;
 442                         continue;
 443                 }
 444                 if (parent->map_token) {
 445                         unmap_extent_buffer(parent, parent->map_token,
 446                                             KM_USER1);
 447                         parent->map_token = NULL;
 448                 }
 449
 450                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
 451                 if (cur)
 452                         uptodate = btrfs_buffer_uptodate(cur, gen);
 453                 else
 454                         uptodate = 0;
 455                 if (!cur || !uptodate) {
 456                         if (cache_only) {
 457                                 free_extent_buffer(cur);
 458                                 continue;
 459                         }
 460                         if (!cur) {
 461                                 cur = read_tree_block(root, blocknr,
 462                                                          blocksize, gen);
 463                         } else if (!uptodate) {
 464                                 btrfs_read_buffer(cur, gen);
 465                         }
 466                 }
 467                 if (search_start == 0)
 468                         search_start = last_block;
 469
 470                 btrfs_tree_lock(cur);
 471                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 472                                         &cur, search_start,
 473                                         min(16 * blocksize,
 474                                             (end_slot - i) * blocksize), 0);
 475                 if (err) {
 476                         btrfs_tree_unlock(cur);
 477                         free_extent_buffer(cur);
 478                         break;
 479                 }
 480                 search_start = cur->start;
 481                 last_block = cur->start;
 482                 *last_ret = search_start;
 483                 btrfs_tree_unlock(cur);
 484                 free_extent_buffer(cur);
 485         }
 486         if (parent->map_token) {
 487                 unmap_extent_buffer(parent, parent->map_token,
 488                                     KM_USER1);
 489                 parent->map_token = NULL;
 490         }
 491         return err;
 492 }
 493
 494 /*
 495  * The leaf data grows from end-to-front in the node.
 496  * this returns the address of the start of the last item,
 497  * which is the stop of the leaf data stack
 498  */
 499 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 500                                          struct extent_buffer *leaf)
 501 {
 502         u32 nr = btrfs_header_nritems(leaf);
 503         if (nr == 0)
 504                 return BTRFS_LEAF_DATA_SIZE(root);
 505         return btrfs_item_offset_nr(leaf, nr - 1);
 506 }
 507
 508 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 509                       int level)
 510 {
 511         struct extent_buffer *parent = NULL;
 512         struct extent_buffer *node = path->nodes[level];
 513         struct btrfs_disk_key parent_key;
 514         struct btrfs_disk_key node_key;
 515         int parent_slot;
 516         int slot;
 517         struct btrfs_key cpukey;
 518         u32 nritems = btrfs_header_nritems(node);
 519
 520         if (path->nodes[level + 1])
 521                 parent = path->nodes[level + 1];
 522
 523         slot = path->slots[level];
 524         BUG_ON(nritems == 0);
 525         if (parent) {
 526                 parent_slot = path->slots[level + 1];
 527                 btrfs_node_key(parent, &parent_key, parent_slot);
 528                 btrfs_node_key(node, &node_key, 0);
 529                 BUG_ON(memcmp(&parent_key, &node_key,
 530                               sizeof(struct btrfs_disk_key)));
 531                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 532                        btrfs_header_bytenr(node));
 533         }
 534         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 535         if (slot != 0) {
 536                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 537                 btrfs_node_key(node, &node_key, slot);
 538                 BUG_ON(comp_keys(&node_key, &cpukey) <= 0);
 539         }
 540         if (slot < nritems - 1) {
 541                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 542                 btrfs_node_key(node, &node_key, slot);
 543                 BUG_ON(comp_keys(&node_key, &cpukey) >= 0);
 544         }
 545         return 0;
 546 }
 547
 548 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 549                       int level)
 550 {
 551         struct extent_buffer *leaf = path->nodes[level];
 552         struct extent_buffer *parent = NULL;
 553         int parent_slot;
 554         struct btrfs_key cpukey;
 555         struct btrfs_disk_key parent_key;
 556         struct btrfs_disk_key leaf_key;
 557         int slot = path->slots[0];
 558
 559         u32 nritems = btrfs_header_nritems(leaf);
 560
 561         if (path->nodes[level + 1])
 562                 parent = path->nodes[level + 1];
 563
 564         if (nritems == 0)
 565                 return 0;
 566
 567         if (parent) {
 568                 parent_slot = path->slots[level + 1];
 569                 btrfs_node_key(parent, &parent_key, parent_slot);
 570                 btrfs_item_key(leaf, &leaf_key, 0);
 571
 572                 BUG_ON(memcmp(&parent_key, &leaf_key,
 573                        sizeof(struct btrfs_disk_key)));
 574                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 575                        btrfs_header_bytenr(leaf));
 576         }
 577 #if 0
 578         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 579                 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
 580                 btrfs_item_key(leaf, &leaf_key, i);
 581                 if (comp_keys(&leaf_key, &cpukey) >= 0) {
 582                         btrfs_print_leaf(root, leaf);
 583                         printk("slot %d offset bad key\n", i);
 584                         BUG_ON(1);
 585                 }
 586                 if (btrfs_item_offset_nr(leaf, i) !=
 587                         btrfs_item_end_nr(leaf, i + 1)) {
 588                         btrfs_print_leaf(root, leaf);
 589                         printk("slot %d offset bad\n", i);
 590                         BUG_ON(1);
 591                 }
 592                 if (i == 0) {
 593                         if (btrfs_item_offset_nr(leaf, i) +
 594                                btrfs_item_size_nr(leaf, i) !=
 595                                BTRFS_LEAF_DATA_SIZE(root)) {
 596                                 btrfs_print_leaf(root, leaf);
 597                                 printk("slot %d first offset bad\n", i);
 598                                 BUG_ON(1);
 599                         }
 600                 }
 601         }
 602         if (nritems > 0) {
 603                 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
 604                                 btrfs_print_leaf(root, leaf);
 605                                 printk("slot %d bad size \n", nritems - 1);
 606                                 BUG_ON(1);
 607                 }
 608         }
 609 #endif
 610         if (slot != 0 && slot < nritems - 1) {
 611                 btrfs_item_key(leaf, &leaf_key, slot);
 612                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 613                 if (comp_keys(&leaf_key, &cpukey) <= 0) {
 614                         btrfs_print_leaf(root, leaf);
 615                         printk("slot %d offset bad key\n", slot);
 616                         BUG_ON(1);
 617                 }
 618                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 619                        btrfs_item_end_nr(leaf, slot)) {
 620                         btrfs_print_leaf(root, leaf);
 621                         printk("slot %d offset bad\n", slot);
 622                         BUG_ON(1);
 623                 }
 624         }
 625         if (slot < nritems - 1) {
 626                 btrfs_item_key(leaf, &leaf_key, slot);
 627                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 628                 BUG_ON(comp_keys(&leaf_key, &cpukey) >= 0);
 629                 if (btrfs_item_offset_nr(leaf, slot) !=
 630                         btrfs_item_end_nr(leaf, slot + 1)) {
 631                         btrfs_print_leaf(root, leaf);
 632                         printk("slot %d offset bad\n", slot);
 633                         BUG_ON(1);
 634                 }
 635         }
 636         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 637                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 638         return 0;
 639 }
 640
 641 static int noinline check_block(struct btrfs_root *root,
 642                                 struct btrfs_path *path, int level)
 643 {
 644         u64 found_start;
 645         return 0;
 646         if (btrfs_header_level(path->nodes[level]) != level)
 647             printk("warning: bad level %Lu wanted %d found %d\n",
 648                    path->nodes[level]->start, level,
 649                    btrfs_header_level(path->nodes[level]));
 650         found_start = btrfs_header_bytenr(path->nodes[level]);
 651         if (found_start != path->nodes[level]->start) {
 652             printk("warning: bad bytentr %Lu found %Lu\n",
 653                    path->nodes[level]->start, found_start);
 654         }
 655 #if 0
 656         struct extent_buffer *buf = path->nodes[level];
 657
 658         if (memcmp_extent_buffer(buf, root->fs_info->fsid,
 659                                  (unsigned long)btrfs_header_fsid(buf),
 660                                  BTRFS_FSID_SIZE)) {
 661                 printk("warning bad block %Lu\n", buf->start);
 662                 return 1;
 663         }
 664 #endif
 665         if (level == 0)
 666                 return check_leaf(root, path, level);
 667         return check_node(root, path, level);
 668 }
 669
 670 /*
 671  * search for key in the extent_buffer.  The items start at offset p,
 672  * and they are item_size apart.  There are 'max' items in p.
 673  *
 674  * the slot in the array is returned via slot, and it points to
 675  * the place where you would insert key if it is not found in
 676  * the array.
 677  *
 678  * slot may point to max if the key is bigger than all of the keys
 679  */
 680 static noinline int generic_bin_search(struct extent_buffer *eb,
 681                                        unsigned long p,
 682                                        int item_size, struct btrfs_key *key,
 683                                        int max, int *slot)
 684 {
 685         int low = 0;
 686         int high = max;
 687         int mid;
 688         int ret;
 689         struct btrfs_disk_key *tmp = NULL;
 690         struct btrfs_disk_key unaligned;
 691         unsigned long offset;
 692         char *map_token = NULL;
 693         char *kaddr = NULL;
 694         unsigned long map_start = 0;
 695         unsigned long map_len = 0;
 696         int err;
 697
 698         while(low < high) {
 699                 mid = (low + high) / 2;
 700                 offset = p + mid * item_size;
 701
 702                 if (!map_token || offset < map_start ||
 703                     (offset + sizeof(struct btrfs_disk_key)) >
 704                     map_start + map_len) {
 705                         if (map_token) {
 706                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 707                                 map_token = NULL;
 708                         }
 709                         err = map_extent_buffer(eb, offset,
 710                                                 sizeof(struct btrfs_disk_key),
 711                                                 &map_token, &kaddr,
 712                                                 &map_start, &map_len, KM_USER0);
 713
 714                         if (!err) {
 715                                 tmp = (struct btrfs_disk_key *)(kaddr + offset -
 716                                                         map_start);
 717                         } else {
 718                                 read_extent_buffer(eb, &unaligned,
 719                                                    offset, sizeof(unaligned));
 720                                 tmp = &unaligned;
 721                         }
 722
 723                 } else {
 724                         tmp = (struct btrfs_disk_key *)(kaddr + offset -
 725                                                         map_start);
 726                 }
 727                 ret = comp_keys(tmp, key);
 728
 729                 if (ret < 0)
 730                         low = mid + 1;
 731                 else if (ret > 0)
 732                         high = mid;
 733                 else {
 734                         *slot = mid;
 735                         if (map_token)
 736                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 737                         return 0;
 738                 }
 739         }
 740         *slot = low;
 741         if (map_token)
 742                 unmap_extent_buffer(eb, map_token, KM_USER0);
 743         return 1;
 744 }
 745
 746 /*
 747  * simple bin_search frontend that does the right thing for
 748  * leaves vs nodes
 749  */
 750 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 751                       int level, int *slot)
 752 {
 753         if (level == 0) {
 754                 return generic_bin_search(eb,
 755                                           offsetof(struct btrfs_leaf, items),
 756                                           sizeof(struct btrfs_item),
 757                                           key, btrfs_header_nritems(eb),
 758                                           slot);
 759         } else {
 760                 return generic_bin_search(eb,
 761                                           offsetof(struct btrfs_node, ptrs),
 762                                           sizeof(struct btrfs_key_ptr),
 763                                           key, btrfs_header_nritems(eb),
 764                                           slot);
 765         }
 766         return -1;
 767 }
 768
 769 static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
 770                                    struct extent_buffer *parent, int slot)
 771 {
 772         int level = btrfs_header_level(parent);
 773         if (slot < 0)
 774                 return NULL;
 775         if (slot >= btrfs_header_nritems(parent))
 776                 return NULL;
 777
 778         BUG_ON(level == 0);
 779
 780         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 781                        btrfs_level_size(root, level - 1),
 782                        btrfs_node_ptr_generation(parent, slot));
 783 }
 784
 785 static noinline int balance_level(struct btrfs_trans_handle *trans,
 786                          struct btrfs_root *root,
 787                          struct btrfs_path *path, int level)
 788 {
 789         struct extent_buffer *right = NULL;
 790         struct extent_buffer *mid;
 791         struct extent_buffer *left = NULL;
 792         struct extent_buffer *parent = NULL;
 793         int ret = 0;
 794         int wret;
 795         int pslot;
 796         int orig_slot = path->slots[level];
 797         int err_on_enospc = 0;
 798         u64 orig_ptr;
 799
 800         if (level == 0)
 801                 return 0;
 802
 803         mid = path->nodes[level];
 804         WARN_ON(!path->locks[level]);
 805         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 806
 807         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 808
 809         if (level < BTRFS_MAX_LEVEL - 1)
 810                 parent = path->nodes[level + 1];
 811         pslot = path->slots[level + 1];
 812
 813         /*
 814          * deal with the case where there is only one pointer in the root
 815          * by promoting the node below to a root
 816          */
 817         if (!parent) {
 818                 struct extent_buffer *child;
 819
 820                 if (btrfs_header_nritems(mid) != 1)
 821                         return 0;
 822
 823                 /* promote the child to a root */
 824                 child = read_node_slot(root, mid, 0);
 825                 btrfs_tree_lock(child);
 826                 BUG_ON(!child);
 827                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child, 0);
 828                 BUG_ON(ret);
 829
 830                 spin_lock(&root->node_lock);
 831                 root->node = child;
 832                 spin_unlock(&root->node_lock);
 833
 834                 add_root_to_dirty_list(root);
 835                 btrfs_tree_unlock(child);
 836                 path->locks[level] = 0;
 837                 path->nodes[level] = NULL;
 838                 clean_tree_block(trans, root, mid);
 839                 btrfs_tree_unlock(mid);
 840                 /* once for the path */
 841                 free_extent_buffer(mid);
 842                 ret = btrfs_free_extent(trans, root, mid->start, mid->len,
 843                                         root->root_key.objectid,
 844                                         btrfs_header_generation(mid), 0, 0, 1);
 845                 /* once for the root ptr */
 846                 free_extent_buffer(mid);
 847                 return ret;
 848         }
 849         if (btrfs_header_nritems(mid) >
 850             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 851                 return 0;
 852
 853         if (btrfs_header_nritems(mid) < 2)
 854                 err_on_enospc = 1;
 855
 856         left = read_node_slot(root, parent, pslot - 1);
 857         if (left) {
 858                 btrfs_tree_lock(left);
 859                 wret = btrfs_cow_block(trans, root, left,
 860                                        parent, pslot - 1, &left, 0);
 861                 if (wret) {
 862                         ret = wret;
 863                         goto enospc;
 864                 }
 865         }
 866         right = read_node_slot(root, parent, pslot + 1);
 867         if (right) {
 868                 btrfs_tree_lock(right);
 869                 wret = btrfs_cow_block(trans, root, right,
 870                                        parent, pslot + 1, &right, 0);
 871                 if (wret) {
 872                         ret = wret;
 873                         goto enospc;
 874                 }
 875         }
 876
 877         /* first, try to make some room in the middle buffer */
 878         if (left) {
 879                 orig_slot += btrfs_header_nritems(left);
 880                 wret = push_node_left(trans, root, left, mid, 1);
 881                 if (wret < 0)
 882                         ret = wret;
 883                 if (btrfs_header_nritems(mid) < 2)
 884                         err_on_enospc = 1;
 885         }
 886
 887         /*
 888          * then try to empty the right most buffer into the middle
 889          */
 890         if (right) {
 891                 wret = push_node_left(trans, root, mid, right, 1);
 892                 if (wret < 0 && wret != -ENOSPC)
 893                         ret = wret;
 894                 if (btrfs_header_nritems(right) == 0) {
 895                         u64 bytenr = right->start;
 896                         u64 generation = btrfs_header_generation(parent);
 897                         u32 blocksize = right->len;
 898
 899                         clean_tree_block(trans, root, right);
 900                         btrfs_tree_unlock(right);
 901                         free_extent_buffer(right);
 902                         right = NULL;
 903                         wret = del_ptr(trans, root, path, level + 1, pslot +
 904                                        1);
 905                         if (wret)
 906                                 ret = wret;
 907                         wret = btrfs_free_extent(trans, root, bytenr,
 908                                                  blocksize,
 909                                                  btrfs_header_owner(parent),
 910                                                  generation, 0, 0, 1);
 911                         if (wret)
 912                                 ret = wret;
 913                 } else {
 914                         struct btrfs_disk_key right_key;
 915                         btrfs_node_key(right, &right_key, 0);
 916                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 917                         btrfs_mark_buffer_dirty(parent);
 918                 }
 919         }
 920         if (btrfs_header_nritems(mid) == 1) {
 921                 /*
 922                  * we're not allowed to leave a node with one item in the
 923                  * tree during a delete.  A deletion from lower in the tree
 924                  * could try to delete the only pointer in this node.
 925                  * So, pull some keys from the left.
 926                  * There has to be a left pointer at this point because
 927                  * otherwise we would have pulled some pointers from the
 928                  * right
 929                  */
 930                 BUG_ON(!left);
 931                 wret = balance_node_right(trans, root, mid, left);
 932                 if (wret < 0) {
 933                         ret = wret;
 934                         goto enospc;
 935                 }
 936                 if (wret == 1) {
 937                         wret = push_node_left(trans, root, left, mid, 1);
 938                         if (wret < 0)
 939                                 ret = wret;
 940                 }
 941                 BUG_ON(wret == 1);
 942         }
 943         if (btrfs_header_nritems(mid) == 0) {
 944                 /* we've managed to empty the middle node, drop it */
 945                 u64 root_gen = btrfs_header_generation(parent);
 946                 u64 bytenr = mid->start;
 947                 u32 blocksize = mid->len;
 948
 949                 clean_tree_block(trans, root, mid);
 950                 btrfs_tree_unlock(mid);
 951                 free_extent_buffer(mid);
 952                 mid = NULL;
 953                 wret = del_ptr(trans, root, path, level + 1, pslot);
 954                 if (wret)
 955                         ret = wret;
 956                 wret = btrfs_free_extent(trans, root, bytenr, blocksize,
 957                                          btrfs_header_owner(parent),
 958                                          root_gen, 0, 0, 1);
 959                 if (wret)
 960                         ret = wret;
 961         } else {
 962                 /* update the parent key to reflect our changes */
 963                 struct btrfs_disk_key mid_key;
 964                 btrfs_node_key(mid, &mid_key, 0);
 965                 btrfs_set_node_key(parent, &mid_key, pslot);
 966                 btrfs_mark_buffer_dirty(parent);
 967         }
 968
 969         /* update the path */
 970         if (left) {
 971                 if (btrfs_header_nritems(left) > orig_slot) {
 972                         extent_buffer_get(left);
 973                         /* left was locked after cow */
 974                         path->nodes[level] = left;
 975                         path->slots[level + 1] -= 1;
 976                         path->slots[level] = orig_slot;
 977                         if (mid) {
 978                                 btrfs_tree_unlock(mid);
 979                                 free_extent_buffer(mid);
 980                         }
 981                 } else {
 982                         orig_slot -= btrfs_header_nritems(left);
 983                         path->slots[level] = orig_slot;
 984                 }
 985         }
 986         /* double check we haven't messed things up */
 987         check_block(root, path, level);
 988         if (orig_ptr !=
 989             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 990                 BUG();
 991 enospc:
 992         if (right) {
 993                 btrfs_tree_unlock(right);
 994                 free_extent_buffer(right);
 995         }
 996         if (left) {
 997                 if (path->nodes[level] != left)
 998                         btrfs_tree_unlock(left);
 999                 free_extent_buffer(left);
1000         }
1001         return ret;
1002 }
1003
1004 /* returns zero if the push worked, non-zero otherwise */
1005 static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
1006                                           struct btrfs_root *root,
1007                                           struct btrfs_path *path, int level)
1008 {
1009         struct extent_buffer *right = NULL;
1010         struct extent_buffer *mid;
1011         struct extent_buffer *left = NULL;
1012         struct extent_buffer *parent = NULL;
1013         int ret = 0;
1014         int wret;
1015         int pslot;
1016         int orig_slot = path->slots[level];
1017         u64 orig_ptr;
1018
1019         if (level == 0)
1020                 return 1;
1021
1022         mid = path->nodes[level];
1023         WARN_ON(btrfs_header_generation(mid) != trans->transid);
1024         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1025
1026         if (level < BTRFS_MAX_LEVEL - 1)
1027                 parent = path->nodes[level + 1];
1028         pslot = path->slots[level + 1];
1029
1030         if (!parent)
1031                 return 1;
1032
1033         left = read_node_slot(root, parent, pslot - 1);
1034
1035         /* first, try to make some room in the middle buffer */
1036         if (left) {
1037                 u32 left_nr;
1038
1039                 btrfs_tree_lock(left);
1040                 left_nr = btrfs_header_nritems(left);
1041                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1042                         wret = 1;
1043                 } else {
1044                         ret = btrfs_cow_block(trans, root, left, parent,
1045                                               pslot - 1, &left, 0);
1046                         if (ret)
1047                                 wret = 1;
1048                         else {
1049                                 wret = push_node_left(trans, root,
1050                                                       left, mid, 0);
1051                         }
1052                 }
1053                 if (wret < 0)
1054                         ret = wret;
1055                 if (wret == 0) {
1056                         struct btrfs_disk_key disk_key;
1057                         orig_slot += left_nr;
1058                         btrfs_node_key(mid, &disk_key, 0);
1059                         btrfs_set_node_key(parent, &disk_key, pslot);
1060                         btrfs_mark_buffer_dirty(parent);
1061                         if (btrfs_header_nritems(left) > orig_slot) {
1062                                 path->nodes[level] = left;
1063                                 path->slots[level + 1] -= 1;
1064                                 path->slots[level] = orig_slot;
1065                                 btrfs_tree_unlock(mid);
1066                                 free_extent_buffer(mid);
1067                         } else {
1068                                 orig_slot -=
1069                                         btrfs_header_nritems(left);
1070                                 path->slots[level] = orig_slot;
1071                                 btrfs_tree_unlock(left);
1072                                 free_extent_buffer(left);
1073                         }
1074                         return 0;
1075                 }
1076                 btrfs_tree_unlock(left);
1077                 free_extent_buffer(left);
1078         }
1079         right = read_node_slot(root, parent, pslot + 1);
1080
1081         /*
1082          * then try to empty the right most buffer into the middle
1083          */
1084         if (right) {
1085                 u32 right_nr;
1086                 btrfs_tree_lock(right);
1087                 right_nr = btrfs_header_nritems(right);
1088                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1089                         wret = 1;
1090                 } else {
1091                         ret = btrfs_cow_block(trans, root, right,
1092                                               parent, pslot + 1,
1093                                               &right, 0);
1094                         if (ret)
1095                                 wret = 1;
1096                         else {
1097                                 wret = balance_node_right(trans, root,
1098                                                           right, mid);
1099                         }
1100                 }
1101                 if (wret < 0)
1102                         ret = wret;
1103                 if (wret == 0) {
1104                         struct btrfs_disk_key disk_key;
1105
1106                         btrfs_node_key(right, &disk_key, 0);
1107                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
1108                         btrfs_mark_buffer_dirty(parent);
1109
1110                         if (btrfs_header_nritems(mid) <= orig_slot) {
1111                                 path->nodes[level] = right;
1112                                 path->slots[level + 1] += 1;
1113                                 path->slots[level] = orig_slot -
1114                                         btrfs_header_nritems(mid);
1115                                 btrfs_tree_unlock(mid);
1116                                 free_extent_buffer(mid);
1117                         } else {
1118                                 btrfs_tree_unlock(right);
1119                                 free_extent_buffer(right);
1120                         }
1121                         return 0;
1122                 }
1123                 btrfs_tree_unlock(right);
1124                 free_extent_buffer(right);
1125         }
1126         return 1;
1127 }
1128
1129 /*
1130  * readahead one full node of leaves
1131  */
1132 static noinline void reada_for_search(struct btrfs_root *root,
1133                                       struct btrfs_path *path,
1134                                       int level, int slot, u64 objectid)
1135 {
1136         struct extent_buffer *node;
1137         struct btrfs_disk_key disk_key;
1138         u32 nritems;
1139         u64 search;
1140         u64 lowest_read;
1141         u64 highest_read;
1142         u64 nread = 0;
1143         int direction = path->reada;
1144         struct extent_buffer *eb;
1145         u32 nr;
1146         u32 blocksize;
1147         u32 nscan = 0;
1148
1149         if (level != 1)
1150                 return;
1151
1152         if (!path->nodes[level])
1153                 return;
1154
1155         node = path->nodes[level];
1156
1157         search = btrfs_node_blockptr(node, slot);
1158         blocksize = btrfs_level_size(root, level - 1);
1159         eb = btrfs_find_tree_block(root, search, blocksize);
1160         if (eb) {
1161                 free_extent_buffer(eb);
1162                 return;
1163         }
1164
1165         highest_read = search;
1166         lowest_read = search;
1167
1168         nritems = btrfs_header_nritems(node);
1169         nr = slot;
1170         while(1) {
1171                 if (direction < 0) {
1172                         if (nr == 0)
1173                                 break;
1174                         nr--;
1175                 } else if (direction > 0) {
1176                         nr++;
1177                         if (nr >= nritems)
1178                                 break;
1179                 }
1180                 if (path->reada < 0 && objectid) {
1181                         btrfs_node_key(node, &disk_key, nr);
1182                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1183                                 break;
1184                 }
1185                 search = btrfs_node_blockptr(node, nr);
1186                 if ((search >= lowest_read && search <= highest_read) ||
1187                     (search < lowest_read && lowest_read - search <= 32768) ||
1188                     (search > highest_read && search - highest_read <= 32768)) {
1189                         readahead_tree_block(root, search, blocksize,
1190                                      btrfs_node_ptr_generation(node, nr));
1191                         nread += blocksize;
1192                 }
1193                 nscan++;
1194                 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
1195                         break;
1196                 if(nread > (1024 * 1024) || nscan > 128)
1197                         break;
1198
1199                 if (search < lowest_read)
1200                         lowest_read = search;
1201                 if (search > highest_read)
1202                         highest_read = search;
1203         }
1204 }
1205
1206 static noinline void unlock_up(struct btrfs_path *path, int level,
1207                                int lowest_unlock)
1208 {
1209         int i;
1210         int skip_level = level;
1211         int no_skips = 0;
1212         struct extent_buffer *t;
1213
1214         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1215                 if (!path->nodes[i])
1216                         break;
1217                 if (!path->locks[i])
1218                         break;
1219                 if (!no_skips && path->slots[i] == 0) {
1220                         skip_level = i + 1;
1221                         continue;
1222                 }
1223                 if (!no_skips && path->keep_locks) {
1224                         u32 nritems;
1225                         t = path->nodes[i];
1226                         nritems = btrfs_header_nritems(t);
1227                         if (nritems < 1 || path->slots[i] >= nritems - 1) {
1228                                 skip_level = i + 1;
1229                                 continue;
1230                         }
1231                 }
1232                 if (skip_level < i && i >= lowest_unlock)
1233                         no_skips = 1;
1234
1235                 t = path->nodes[i];
1236                 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
1237                         btrfs_tree_unlock(t);
1238                         path->locks[i] = 0;
1239                 }
1240         }
1241 }
1242
1243 /*
1244  * look for key in the tree.  path is filled in with nodes along the way
1245  * if key is found, we return zero and you can find the item in the leaf
1246  * level of the path (level 0)
1247  *
1248  * If the key isn't found, the path points to the slot where it should
1249  * be inserted, and 1 is returned.  If there are other errors during the
1250  * search a negative error number is returned.
1251  *
1252  * if ins_len > 0, nodes and leaves will be split as we walk down the
1253  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
1254  * possible)
1255  */
1256 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1257                       *root, struct btrfs_key *key, struct btrfs_path *p, int
1258                       ins_len, int cow)
1259 {
1260         struct extent_buffer *b;
1261         struct extent_buffer *tmp;
1262         int slot;
1263         int ret;
1264         int level;
1265         int should_reada = p->reada;
1266         int lowest_unlock = 1;
1267         int blocksize;
1268         u8 lowest_level = 0;
1269         u64 blocknr;
1270         u64 gen;
1271         struct btrfs_key prealloc_block;
1272
1273         lowest_level = p->lowest_level;
1274         WARN_ON(lowest_level && ins_len);
1275         WARN_ON(p->nodes[0] != NULL);
1276         WARN_ON(cow && root == root->fs_info->extent_root &&
1277                 !mutex_is_locked(&root->fs_info->alloc_mutex));
1278         if (ins_len < 0)
1279                 lowest_unlock = 2;
1280
1281         prealloc_block.objectid = 0;
1282
1283 again:
1284         if (p->skip_locking)
1285                 b = btrfs_root_node(root);
1286         else
1287                 b = btrfs_lock_root_node(root);
1288
1289         while (b) {
1290                 level = btrfs_header_level(b);
1291
1292                 /*
1293                  * setup the path here so we can release it under lock
1294                  * contention with the cow code
1295                  */
1296                 p->nodes[level] = b;
1297                 if (!p->skip_locking)
1298                         p->locks[level] = 1;
1299
1300                 if (cow) {
1301                         int wret;
1302
1303                         /* is a cow on this block not required */
1304                         spin_lock(&root->fs_info->hash_lock);
1305                         if (btrfs_header_generation(b) == trans->transid &&
1306                             !btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) {
1307                                 spin_unlock(&root->fs_info->hash_lock);
1308                                 goto cow_done;
1309                         }
1310                         spin_unlock(&root->fs_info->hash_lock);
1311
1312                         /* ok, we have to cow, is our old prealloc the right
1313                          * size?
1314                          */
1315                         if (prealloc_block.objectid &&
1316                             prealloc_block.offset != b->len) {
1317                                 btrfs_free_reserved_extent(root,
1318                                            prealloc_block.objectid,
1319                                            prealloc_block.offset);
1320                                 prealloc_block.objectid = 0;
1321                         }
1322
1323                         /*
1324                          * for higher level blocks, try not to allocate blocks
1325                          * with the block and the parent locks held.
1326                          */
1327                         if (level > 1 && !prealloc_block.objectid &&
1328                             btrfs_path_lock_waiting(p, level)) {
1329                                 u32 size = b->len;
1330                                 u64 hint = b->start;
1331
1332                                 btrfs_release_path(root, p);
1333                                 ret = btrfs_reserve_extent(trans, root,
1334                                                            size, size, 0,
1335                                                            hint, (u64)-1,
1336                                                            &prealloc_block, 0);
1337                                 BUG_ON(ret);
1338                                 goto again;
1339                         }
1340
1341                         wret = btrfs_cow_block(trans, root, b,
1342                                                p->nodes[level + 1],
1343                                                p->slots[level + 1],
1344                                                &b, prealloc_block.objectid);
1345                         prealloc_block.objectid = 0;
1346                         if (wret) {
1347                                 free_extent_buffer(b);
1348                                 ret = wret;
1349                                 goto done;
1350                         }
1351                 }
1352 cow_done:
1353                 BUG_ON(!cow && ins_len);
1354                 if (level != btrfs_header_level(b))
1355                         WARN_ON(1);
1356                 level = btrfs_header_level(b);
1357
1358                 p->nodes[level] = b;
1359                 if (!p->skip_locking)
1360                         p->locks[level] = 1;
1361
1362                 ret = check_block(root, p, level);
1363                 if (ret) {
1364                         ret = -1;
1365                         goto done;
1366                 }
1367
1368                 ret = bin_search(b, key, level, &slot);
1369                 if (level != 0) {
1370                         if (ret && slot > 0)
1371                                 slot -= 1;
1372                         p->slots[level] = slot;
1373                         if (ins_len > 0 && btrfs_header_nritems(b) >=
1374                             BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
1375                                 int sret = split_node(trans, root, p, level);
1376                                 BUG_ON(sret > 0);
1377                                 if (sret) {
1378                                         ret = sret;
1379                                         goto done;
1380                                 }
1381                                 b = p->nodes[level];
1382                                 slot = p->slots[level];
1383                         } else if (ins_len < 0) {
1384                                 int sret = balance_level(trans, root, p,
1385                                                          level);
1386                                 if (sret) {
1387                                         ret = sret;
1388                                         goto done;
1389                                 }
1390                                 b = p->nodes[level];
1391                                 if (!b) {
1392                                         btrfs_release_path(NULL, p);
1393                                         goto again;
1394                                 }
1395                                 slot = p->slots[level];
1396                                 BUG_ON(btrfs_header_nritems(b) == 1);
1397                         }
1398                         unlock_up(p, level, lowest_unlock);
1399
1400                         /* this is only true while dropping a snapshot */
1401                         if (level == lowest_level) {
1402                                 break;
1403                         }
1404
1405                         blocknr = btrfs_node_blockptr(b, slot);
1406                         gen = btrfs_node_ptr_generation(b, slot);
1407                         blocksize = btrfs_level_size(root, level - 1);
1408
1409                         tmp = btrfs_find_tree_block(root, blocknr, blocksize);
1410                         if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
1411                                 b = tmp;
1412                         } else {
1413                                 /*
1414                                  * reduce lock contention at high levels
1415                                  * of the btree by dropping locks before
1416                                  * we read.
1417                                  */
1418                                 if (level > 1) {
1419                                         btrfs_release_path(NULL, p);
1420                                         if (tmp)
1421                                                 free_extent_buffer(tmp);
1422                                         if (should_reada)
1423                                                 reada_for_search(root, p,
1424                                                                  level, slot,
1425                                                                  key->objectid);
1426
1427                                         tmp = read_tree_block(root, blocknr,
1428                                                          blocksize, gen);
1429                                         if (tmp)
1430                                                 free_extent_buffer(tmp);
1431                                         goto again;
1432                                 } else {
1433                                         if (tmp)
1434                                                 free_extent_buffer(tmp);
1435                                         if (should_reada)
1436                                                 reada_for_search(root, p,
1437                                                                  level, slot,
1438                                                                  key->objectid);
1439                                         b = read_node_slot(root, b, slot);
1440                                 }
1441                         }
1442                         if (!p->skip_locking)
1443                                 btrfs_tree_lock(b);
1444                 } else {
1445                         p->slots[level] = slot;
1446                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1447                             sizeof(struct btrfs_item) + ins_len) {
1448                                 int sret = split_leaf(trans, root, key,
1449                                                       p, ins_len, ret == 0);
1450                                 BUG_ON(sret > 0);
1451                                 if (sret) {
1452                                         ret = sret;
1453                                         goto done;
1454                                 }
1455                         }
1456                         unlock_up(p, level, lowest_unlock);
1457                         goto done;
1458                 }
1459         }
1460         ret = 1;
1461 done:
1462         if (prealloc_block.objectid) {
1463                 btrfs_free_reserved_extent(root,
1464                            prealloc_block.objectid,
1465                            prealloc_block.offset);
1466         }
1467
1468         return ret;
1469 }
1470
1471 /*
1472  * adjust the pointers going up the tree, starting at level
1473  * making sure the right key of each node is points to 'key'.
1474  * This is used after shifting pointers to the left, so it stops
1475  * fixing up pointers when a given leaf/node is not in slot 0 of the
1476  * higher levels
1477  *
1478  * If this fails to write a tree block, it returns -1, but continues
1479  * fixing up the blocks in ram so the tree is consistent.
1480  */
1481 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1482                           struct btrfs_root *root, struct btrfs_path *path,
1483                           struct btrfs_disk_key *key, int level)
1484 {
1485         int i;
1486         int ret = 0;
1487         struct extent_buffer *t;
1488
1489         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1490                 int tslot = path->slots[i];
1491                 if (!path->nodes[i])
1492                         break;
1493                 t = path->nodes[i];
1494                 btrfs_set_node_key(t, key, tslot);
1495                 btrfs_mark_buffer_dirty(path->nodes[i]);
1496                 if (tslot != 0)
1497                         break;
1498         }
1499         return ret;
1500 }
1501
1502 /*
1503  * try to push data from one node into the next node left in the
1504  * tree.
1505  *
1506  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1507  * error, and > 0 if there was no room in the left hand block.
1508  */
1509 static int push_node_left(struct btrfs_trans_handle *trans,
1510                           struct btrfs_root *root, struct extent_buffer *dst,
1511                           struct extent_buffer *src, int empty)
1512 {
1513         int push_items = 0;
1514         int src_nritems;
1515         int dst_nritems;
1516         int ret = 0;
1517
1518         src_nritems = btrfs_header_nritems(src);
1519         dst_nritems = btrfs_header_nritems(dst);
1520         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1521         WARN_ON(btrfs_header_generation(src) != trans->transid);
1522         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1523
1524         if (!empty && src_nritems <= 8)
1525                 return 1;
1526
1527         if (push_items <= 0) {
1528                 return 1;
1529         }
1530
1531         if (empty) {
1532                 push_items = min(src_nritems, push_items);
1533                 if (push_items < src_nritems) {
1534                         /* leave at least 8 pointers in the node if
1535                          * we aren't going to empty it
1536                          */
1537                         if (src_nritems - push_items < 8) {
1538                                 if (push_items <= 8)
1539                                         return 1;
1540                                 push_items -= 8;
1541                         }
1542                 }
1543         } else
1544                 push_items = min(src_nritems - 8, push_items);
1545
1546         copy_extent_buffer(dst, src,
1547                            btrfs_node_key_ptr_offset(dst_nritems),
1548                            btrfs_node_key_ptr_offset(0),
1549                            push_items * sizeof(struct btrfs_key_ptr));
1550
1551         if (push_items < src_nritems) {
1552                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1553                                       btrfs_node_key_ptr_offset(push_items),
1554                                       (src_nritems - push_items) *
1555                                       sizeof(struct btrfs_key_ptr));
1556         }
1557         btrfs_set_header_nritems(src, src_nritems - push_items);
1558         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1559         btrfs_mark_buffer_dirty(src);
1560         btrfs_mark_buffer_dirty(dst);
1561         return ret;
1562 }
1563
1564 /*
1565  * try to push data from one node into the next node right in the
1566  * tree.
1567  *
1568  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1569  * error, and > 0 if there was no room in the right hand block.
1570  *
1571  * this will  only push up to 1/2 the contents of the left node over
1572  */
1573 static int balance_node_right(struct btrfs_trans_handle *trans,
1574                               struct btrfs_root *root,
1575                               struct extent_buffer *dst,
1576                               struct extent_buffer *src)
1577 {
1578         int push_items = 0;
1579         int max_push;
1580         int src_nritems;
1581         int dst_nritems;
1582         int ret = 0;
1583
1584         WARN_ON(btrfs_header_generation(src) != trans->transid);
1585         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1586
1587         src_nritems = btrfs_header_nritems(src);
1588         dst_nritems = btrfs_header_nritems(dst);
1589         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1590         if (push_items <= 0) {
1591                 return 1;
1592         }
1593
1594         if (src_nritems < 4) {
1595                 return 1;
1596         }
1597
1598         max_push = src_nritems / 2 + 1;
1599         /* don't try to empty the node */
1600         if (max_push >= src_nritems) {
1601                 return 1;
1602         }
1603
1604         if (max_push < push_items)
1605                 push_items = max_push;
1606
1607         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1608                                       btrfs_node_key_ptr_offset(0),
1609                                       (dst_nritems) *
1610                                       sizeof(struct btrfs_key_ptr));
1611
1612         copy_extent_buffer(dst, src,
1613                            btrfs_node_key_ptr_offset(0),
1614                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1615                            push_items * sizeof(struct btrfs_key_ptr));
1616
1617         btrfs_set_header_nritems(src, src_nritems - push_items);
1618         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1619
1620         btrfs_mark_buffer_dirty(src);
1621         btrfs_mark_buffer_dirty(dst);
1622         return ret;
1623 }
1624
1625 /*
1626  * helper function to insert a new root level in the tree.
1627  * A new node is allocated, and a single item is inserted to
1628  * point to the existing root
1629  *
1630  * returns zero on success or < 0 on failure.
1631  */
1632 static int noinline insert_new_root(struct btrfs_trans_handle *trans,
1633                            struct btrfs_root *root,
1634                            struct btrfs_path *path, int level)
1635 {
1636         u64 root_gen;
1637         u64 lower_gen;
1638         struct extent_buffer *lower;
1639         struct extent_buffer *c;
1640         struct extent_buffer *old;
1641         struct btrfs_disk_key lower_key;
1642
1643         BUG_ON(path->nodes[level]);
1644         BUG_ON(path->nodes[level-1] != root->node);
1645
1646         if (root->ref_cows)
1647                 root_gen = trans->transid;
1648         else
1649                 root_gen = 0;
1650
1651         lower = path->nodes[level-1];
1652         if (level == 1)
1653                 btrfs_item_key(lower, &lower_key, 0);
1654         else
1655                 btrfs_node_key(lower, &lower_key, 0);
1656
1657         c = btrfs_alloc_free_block(trans, root, root->nodesize,
1658                                    root->root_key.objectid,
1659                                    root_gen, le64_to_cpu(lower_key.objectid),
1660                                    level, root->node->start, 0);
1661         if (IS_ERR(c))
1662                 return PTR_ERR(c);
1663
1664         memset_extent_buffer(c, 0, 0, root->nodesize);
1665         btrfs_set_header_nritems(c, 1);
1666         btrfs_set_header_level(c, level);
1667         btrfs_set_header_bytenr(c, c->start);
1668         btrfs_set_header_generation(c, trans->transid);
1669         btrfs_set_header_owner(c, root->root_key.objectid);
1670
1671         write_extent_buffer(c, root->fs_info->fsid,
1672                             (unsigned long)btrfs_header_fsid(c),
1673                             BTRFS_FSID_SIZE);
1674
1675         write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
1676                             (unsigned long)btrfs_header_chunk_tree_uuid(c),
1677                             BTRFS_UUID_SIZE);
1678
1679         btrfs_set_node_key(c, &lower_key, 0);
1680         btrfs_set_node_blockptr(c, 0, lower->start);
1681         lower_gen = btrfs_header_generation(lower);
1682         WARN_ON(lower_gen == 0);
1683
1684         btrfs_set_node_ptr_generation(c, 0, lower_gen);
1685
1686         btrfs_mark_buffer_dirty(c);
1687
1688         spin_lock(&root->node_lock);
1689         old = root->node;
1690         root->node = c;
1691         spin_unlock(&root->node_lock);
1692
1693         /* the super has an extra ref to root->node */
1694         free_extent_buffer(old);
1695
1696         add_root_to_dirty_list(root);
1697         extent_buffer_get(c);
1698         path->nodes[level] = c;
1699         path->locks[level] = 1;
1700         path->slots[level] = 0;
1701
1702         if (root->ref_cows && lower_gen != trans->transid) {
1703                 struct btrfs_path *back_path = btrfs_alloc_path();
1704                 int ret;
1705                 mutex_lock(&root->fs_info->alloc_mutex);
1706                 ret = btrfs_insert_extent_backref(trans,
1707                                                   root->fs_info->extent_root,
1708                                                   path, lower->start,
1709                                                   root->root_key.objectid,
1710                                                   trans->transid, 0, 0);
1711                 BUG_ON(ret);
1712                 mutex_unlock(&root->fs_info->alloc_mutex);
1713                 btrfs_free_path(back_path);
1714         }
1715         return 0;
1716 }
1717
1718 /*
1719  * worker function to insert a single pointer in a node.
1720  * the node should have enough room for the pointer already
1721  *
1722  * slot and level indicate where you want the key to go, and
1723  * blocknr is the block the key points to.
1724  *
1725  * returns zero on success and < 0 on any error
1726  */
1727 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1728                       *root, struct btrfs_path *path, struct btrfs_disk_key
1729                       *key, u64 bytenr, int slot, int level)
1730 {
1731         struct extent_buffer *lower;
1732         int nritems;
1733
1734         BUG_ON(!path->nodes[level]);
1735         lower = path->nodes[level];
1736         nritems = btrfs_header_nritems(lower);
1737         if (slot > nritems)
1738                 BUG();
1739         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1740                 BUG();
1741         if (slot != nritems) {
1742                 memmove_extent_buffer(lower,
1743                               btrfs_node_key_ptr_offset(slot + 1),
1744                               btrfs_node_key_ptr_offset(slot),
1745                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1746         }
1747         btrfs_set_node_key(lower, key, slot);
1748         btrfs_set_node_blockptr(lower, slot, bytenr);
1749         WARN_ON(trans->transid == 0);
1750         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
1751         btrfs_set_header_nritems(lower, nritems + 1);
1752         btrfs_mark_buffer_dirty(lower);
1753         return 0;
1754 }
1755
1756 /*
1757  * split the node at the specified level in path in two.
1758  * The path is corrected to point to the appropriate node after the split
1759  *
1760  * Before splitting this tries to make some room in the node by pushing
1761  * left and right, if either one works, it returns right away.
1762  *
1763  * returns 0 on success and < 0 on failure
1764  */
1765 static noinline int split_node(struct btrfs_trans_handle *trans,
1766                                struct btrfs_root *root,
1767                                struct btrfs_path *path, int level)
1768 {
1769         u64 root_gen;
1770         struct extent_buffer *c;
1771         struct extent_buffer *split;
1772         struct btrfs_disk_key disk_key;
1773         int mid;
1774         int ret;
1775         int wret;
1776         u32 c_nritems;
1777
1778         c = path->nodes[level];
1779         WARN_ON(btrfs_header_generation(c) != trans->transid);
1780         if (c == root->node) {
1781                 /* trying to split the root, lets make a new one */
1782                 ret = insert_new_root(trans, root, path, level + 1);
1783                 if (ret)
1784                         return ret;
1785         } else {
1786                 ret = push_nodes_for_insert(trans, root, path, level);
1787                 c = path->nodes[level];
1788                 if (!ret && btrfs_header_nritems(c) <
1789                     BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
1790                         return 0;
1791                 if (ret < 0)
1792                         return ret;
1793         }
1794
1795         c_nritems = btrfs_header_nritems(c);
1796         if (root->ref_cows)
1797                 root_gen = trans->transid;
1798         else
1799                 root_gen = 0;
1800
1801         btrfs_node_key(c, &disk_key, 0);
1802         split = btrfs_alloc_free_block(trans, root, root->nodesize,
1803                                          root->root_key.objectid,
1804                                          root_gen,
1805                                          btrfs_disk_key_objectid(&disk_key),
1806                                          level, c->start, 0);
1807         if (IS_ERR(split))
1808                 return PTR_ERR(split);
1809
1810         btrfs_set_header_flags(split, btrfs_header_flags(c));
1811         btrfs_set_header_level(split, btrfs_header_level(c));
1812         btrfs_set_header_bytenr(split, split->start);
1813         btrfs_set_header_generation(split, trans->transid);
1814         btrfs_set_header_owner(split, root->root_key.objectid);
1815         btrfs_set_header_flags(split, 0);
1816         write_extent_buffer(split, root->fs_info->fsid,
1817                             (unsigned long)btrfs_header_fsid(split),
1818                             BTRFS_FSID_SIZE);
1819         write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
1820                             (unsigned long)btrfs_header_chunk_tree_uuid(split),
1821                             BTRFS_UUID_SIZE);
1822
1823         mid = (c_nritems + 1) / 2;
1824
1825         copy_extent_buffer(split, c,
1826                            btrfs_node_key_ptr_offset(0),
1827                            btrfs_node_key_ptr_offset(mid),
1828                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1829         btrfs_set_header_nritems(split, c_nritems - mid);
1830         btrfs_set_header_nritems(c, mid);
1831         ret = 0;
1832
1833         btrfs_mark_buffer_dirty(c);
1834         btrfs_mark_buffer_dirty(split);
1835
1836         btrfs_node_key(split, &disk_key, 0);
1837         wret = insert_ptr(trans, root, path, &disk_key, split->start,
1838                           path->slots[level + 1] + 1,
1839                           level + 1);
1840         if (wret)
1841                 ret = wret;
1842
1843         if (path->slots[level] >= mid) {
1844                 path->slots[level] -= mid;
1845                 btrfs_tree_unlock(c);
1846                 free_extent_buffer(c);
1847                 path->nodes[level] = split;
1848                 path->slots[level + 1] += 1;
1849         } else {
1850                 btrfs_tree_unlock(split);
1851                 free_extent_buffer(split);
1852         }
1853         return ret;
1854 }
1855
1856 /*
1857  * how many bytes are required to store the items in a leaf.  start
1858  * and nr indicate which items in the leaf to check.  This totals up the
1859  * space used both by the item structs and the item data
1860  */
1861 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1862 {
1863         int data_len;
1864         int nritems = btrfs_header_nritems(l);
1865         int end = min(nritems, start + nr) - 1;
1866
1867         if (!nr)
1868                 return 0;
1869         data_len = btrfs_item_end_nr(l, start);
1870         data_len = data_len - btrfs_item_offset_nr(l, end);
1871         data_len += sizeof(struct btrfs_item) * nr;
1872         WARN_ON(data_len < 0);
1873         return data_len;
1874 }
1875
1876 /*
1877  * The space between the end of the leaf items and
1878  * the start of the leaf data.  IOW, how much room
1879  * the leaf has left for both items and data
1880  */
1881 int noinline btrfs_leaf_free_space(struct btrfs_root *root,
1882                                    struct extent_buffer *leaf)
1883 {
1884         int nritems = btrfs_header_nritems(leaf);
1885         int ret;
1886         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1887         if (ret < 0) {
1888                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1889                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
1890                        leaf_space_used(leaf, 0, nritems), nritems);
1891         }
1892         return ret;
1893 }
1894
1895 /*
1896  * push some data in the path leaf to the right, trying to free up at
1897  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1898  *
1899  * returns 1 if the push failed because the other node didn't have enough
1900  * room, 0 if everything worked out and < 0 if there were major errors.
1901  */
1902 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1903                            *root, struct btrfs_path *path, int data_size,
1904                            int empty)
1905 {
1906         struct extent_buffer *left = path->nodes[0];
1907         struct extent_buffer *right;
1908         struct extent_buffer *upper;
1909         struct btrfs_disk_key disk_key;
1910         int slot;
1911         u32 i;
1912         int free_space;
1913         int push_space = 0;
1914         int push_items = 0;
1915         struct btrfs_item *item;
1916         u32 left_nritems;
1917         u32 nr;
1918         u32 right_nritems;
1919         u32 data_end;
1920         u32 this_item_size;
1921         int ret;
1922
1923         slot = path->slots[1];
1924         if (!path->nodes[1]) {
1925                 return 1;
1926         }
1927         upper = path->nodes[1];
1928         if (slot >= btrfs_header_nritems(upper) - 1)
1929                 return 1;
1930
1931         WARN_ON(!btrfs_tree_locked(path->nodes[1]));
1932
1933         right = read_node_slot(root, upper, slot + 1);
1934         btrfs_tree_lock(right);
1935         free_space = btrfs_leaf_free_space(root, right);
1936         if (free_space < data_size + sizeof(struct btrfs_item))
1937                 goto out_unlock;
1938
1939         /* cow and double check */
1940         ret = btrfs_cow_block(trans, root, right, upper,
1941                               slot + 1, &right, 0);
1942         if (ret)
1943                 goto out_unlock;
1944
1945         free_space = btrfs_leaf_free_space(root, right);
1946         if (free_space < data_size + sizeof(struct btrfs_item))
1947                 goto out_unlock;
1948
1949         left_nritems = btrfs_header_nritems(left);
1950         if (left_nritems == 0)
1951                 goto out_unlock;
1952
1953         if (empty)
1954                 nr = 0;
1955         else
1956                 nr = 1;
1957
1958         i = left_nritems - 1;
1959         while (i >= nr) {
1960                 item = btrfs_item_nr(left, i);
1961
1962                 if (path->slots[0] == i)
1963                         push_space += data_size + sizeof(*item);
1964
1965                 if (!left->map_token) {
1966                         map_extent_buffer(left, (unsigned long)item,
1967                                         sizeof(struct btrfs_item),
1968                                         &left->map_token, &left->kaddr,
1969                                         &left->map_start, &left->map_len,
1970                                         KM_USER1);
1971                 }
1972
1973                 this_item_size = btrfs_item_size(left, item);
1974                 if (this_item_size + sizeof(*item) + push_space > free_space)
1975                         break;
1976                 push_items++;
1977                 push_space += this_item_size + sizeof(*item);
1978                 if (i == 0)
1979                         break;
1980                 i--;
1981         }
1982         if (left->map_token) {
1983                 unmap_extent_buffer(left, left->map_token, KM_USER1);
1984                 left->map_token = NULL;
1985         }
1986
1987         if (push_items == 0)
1988                 goto out_unlock;
1989
1990         if (!empty && push_items == left_nritems)
1991                 WARN_ON(1);
1992
1993         /* push left to right */
1994         right_nritems = btrfs_header_nritems(right);
1995
1996         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1997         push_space -= leaf_data_end(root, left);
1998
1999         /* make room in the right data area */
2000         data_end = leaf_data_end(root, right);
2001         memmove_extent_buffer(right,
2002                               btrfs_leaf_data(right) + data_end - push_space,
2003                               btrfs_leaf_data(right) + data_end,
2004                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
2005
2006         /* copy from the left data area */
2007         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
2008                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
2009                      btrfs_leaf_data(left) + leaf_data_end(root, left),
2010                      push_space);
2011
2012         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
2013                               btrfs_item_nr_offset(0),
2014                               right_nritems * sizeof(struct btrfs_item));
2015
2016         /* copy the items from left to right */
2017         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
2018                    btrfs_item_nr_offset(left_nritems - push_items),
2019                    push_items * sizeof(struct btrfs_item));
2020
2021         /* update the item pointers */
2022         right_nritems += push_items;
2023         btrfs_set_header_nritems(right, right_nritems);
2024         push_space = BTRFS_LEAF_DATA_SIZE(root);
2025         for (i = 0; i < right_nritems; i++) {
2026                 item = btrfs_item_nr(right, i);
2027                 if (!right->map_token) {
2028                         map_extent_buffer(right, (unsigned long)item,
2029                                         sizeof(struct btrfs_item),
2030                                         &right->map_token, &right->kaddr,
2031                                         &right->map_start, &right->map_len,
2032                                         KM_USER1);
2033                 }
2034                 push_space -= btrfs_item_size(right, item);
2035                 btrfs_set_item_offset(right, item, push_space);
2036         }
2037
2038         if (right->map_token) {
2039                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2040                 right->map_token = NULL;
2041         }
2042         left_nritems -= push_items;
2043         btrfs_set_header_nritems(left, left_nritems);
2044
2045         if (left_nritems)
2046                 btrfs_mark_buffer_dirty(left);
2047         btrfs_mark_buffer_dirty(right);
2048
2049         btrfs_item_key(right, &disk_key, 0);
2050         btrfs_set_node_key(upper, &disk_key, slot + 1);
2051         btrfs_mark_buffer_dirty(upper);
2052
2053         /* then fixup the leaf pointer in the path */
2054         if (path->slots[0] >= left_nritems) {
2055                 path->slots[0] -= left_nritems;
2056                 if (btrfs_header_nritems(path->nodes[0]) == 0)
2057                         clean_tree_block(trans, root, path->nodes[0]);
2058                 btrfs_tree_unlock(path->nodes[0]);
2059                 free_extent_buffer(path->nodes[0]);
2060                 path->nodes[0] = right;
2061                 path->slots[1] += 1;
2062         } else {
2063                 btrfs_tree_unlock(right);
2064                 free_extent_buffer(right);
2065         }
2066         return 0;
2067
2068 out_unlock:
2069         btrfs_tree_unlock(right);
2070         free_extent_buffer(right);
2071         return 1;
2072 }
2073
2074 /*
2075  * push some data in the path leaf to the left, trying to free up at
2076  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
2077  */
2078 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
2079                           *root, struct btrfs_path *path, int data_size,
2080                           int empty)
2081 {
2082         struct btrfs_disk_key disk_key;
2083         struct extent_buffer *right = path->nodes[0];
2084         struct extent_buffer *left;
2085         int slot;
2086         int i;
2087         int free_space;
2088         int push_space = 0;
2089         int push_items = 0;
2090         struct btrfs_item *item;
2091         u32 old_left_nritems;
2092         u32 right_nritems;
2093         u32 nr;
2094         int ret = 0;
2095         int wret;
2096         u32 this_item_size;
2097         u32 old_left_item_size;
2098
2099         slot = path->slots[1];
2100         if (slot == 0)
2101                 return 1;
2102         if (!path->nodes[1])
2103                 return 1;
2104
2105         right_nritems = btrfs_header_nritems(right);
2106         if (right_nritems == 0) {
2107                 return 1;
2108         }
2109
2110         WARN_ON(!btrfs_tree_locked(path->nodes[1]));
2111
2112         left = read_node_slot(root, path->nodes[1], slot - 1);
2113         btrfs_tree_lock(left);
2114         free_space = btrfs_leaf_free_space(root, left);
2115         if (free_space < data_size + sizeof(struct btrfs_item)) {
2116                 ret = 1;
2117                 goto out;
2118         }
2119
2120         /* cow and double check */
2121         ret = btrfs_cow_block(trans, root, left,
2122                               path->nodes[1], slot - 1, &left, 0);
2123         if (ret) {
2124                 /* we hit -ENOSPC, but it isn't fatal here */
2125                 ret = 1;
2126                 goto out;
2127         }
2128
2129         free_space = btrfs_leaf_free_space(root, left);
2130         if (free_space < data_size + sizeof(struct btrfs_item)) {
2131                 ret = 1;
2132                 goto out;
2133         }
2134
2135         if (empty)
2136                 nr = right_nritems;
2137         else
2138                 nr = right_nritems - 1;
2139
2140         for (i = 0; i < nr; i++) {
2141                 item = btrfs_item_nr(right, i);
2142                 if (!right->map_token) {
2143                         map_extent_buffer(right, (unsigned long)item,
2144                                         sizeof(struct btrfs_item),
2145                                         &right->map_token, &right->kaddr,
2146                                         &right->map_start, &right->map_len,
2147                                         KM_USER1);
2148                 }
2149
2150                 if (path->slots[0] == i)
2151                         push_space += data_size + sizeof(*item);
2152
2153                 this_item_size = btrfs_item_size(right, item);
2154                 if (this_item_size + sizeof(*item) + push_space > free_space)
2155                         break;
2156
2157                 push_items++;
2158                 push_space += this_item_size + sizeof(*item);
2159         }
2160
2161         if (right->map_token) {
2162                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2163                 right->map_token = NULL;
2164         }
2165
2166         if (push_items == 0) {
2167                 ret = 1;
2168                 goto out;
2169         }
2170         if (!empty && push_items == btrfs_header_nritems(right))
2171                 WARN_ON(1);
2172
2173         /* push data from right to left */
2174         copy_extent_buffer(left, right,
2175                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
2176                            btrfs_item_nr_offset(0),
2177                            push_items * sizeof(struct btrfs_item));
2178
2179         push_space = BTRFS_LEAF_DATA_SIZE(root) -
2180                      btrfs_item_offset_nr(right, push_items -1);
2181
2182         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
2183                      leaf_data_end(root, left) - push_space,
2184                      btrfs_leaf_data(right) +
2185                      btrfs_item_offset_nr(right, push_items - 1),
2186                      push_space);
2187         old_left_nritems = btrfs_header_nritems(left);
2188         BUG_ON(old_left_nritems < 0);
2189
2190         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
2191         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
2192                 u32 ioff;
2193
2194                 item = btrfs_item_nr(left, i);
2195                 if (!left->map_token) {
2196                         map_extent_buffer(left, (unsigned long)item,
2197                                         sizeof(struct btrfs_item),
2198                                         &left->map_token, &left->kaddr,
2199                                         &left->map_start, &left->map_len,
2200                                         KM_USER1);
2201                 }
2202
2203                 ioff = btrfs_item_offset(left, item);
2204                 btrfs_set_item_offset(left, item,
2205                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
2206         }
2207         btrfs_set_header_nritems(left, old_left_nritems + push_items);
2208         if (left->map_token) {
2209                 unmap_extent_buffer(left, left->map_token, KM_USER1);
2210                 left->map_token = NULL;
2211         }
2212
2213         /* fixup right node */
2214         if (push_items > right_nritems) {
2215                 printk("push items %d nr %u\n", push_items, right_nritems);
2216                 WARN_ON(1);
2217         }
2218
2219         if (push_items < right_nritems) {
2220                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
2221                                                   leaf_data_end(root, right);
2222                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
2223                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
2224                                       btrfs_leaf_data(right) +
2225                                       leaf_data_end(root, right), push_space);
2226
2227                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
2228                               btrfs_item_nr_offset(push_items),
2229                              (btrfs_header_nritems(right) - push_items) *
2230                              sizeof(struct btrfs_item));
2231         }
2232         right_nritems -= push_items;
2233         btrfs_set_header_nritems(right, right_nritems);
2234         push_space = BTRFS_LEAF_DATA_SIZE(root);
2235         for (i = 0; i < right_nritems; i++) {
2236                 item = btrfs_item_nr(right, i);
2237
2238                 if (!right->map_token) {
2239                         map_extent_buffer(right, (unsigned long)item,
2240                                         sizeof(struct btrfs_item),
2241                                         &right->map_token, &right->kaddr,
2242                                         &right->map_start, &right->map_len,
2243                                         KM_USER1);
2244                 }
2245
2246                 push_space = push_space - btrfs_item_size(right, item);
2247                 btrfs_set_item_offset(right, item, push_space);
2248         }
2249         if (right->map_token) {
2250                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2251                 right->map_token = NULL;
2252         }
2253
2254         btrfs_mark_buffer_dirty(left);
2255         if (right_nritems)
2256                 btrfs_mark_buffer_dirty(right);
2257
2258         btrfs_item_key(right, &disk_key, 0);
2259         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
2260         if (wret)
2261                 ret = wret;
2262
2263         /* then fixup the leaf pointer in the path */
2264         if (path->slots[0] < push_items) {
2265                 path->slots[0] += old_left_nritems;
2266                 if (btrfs_header_nritems(path->nodes[0]) == 0)
2267                         clean_tree_block(trans, root, path->nodes[0]);
2268                 btrfs_tree_unlock(path->nodes[0]);
2269                 free_extent_buffer(path->nodes[0]);
2270                 path->nodes[0] = left;
2271                 path->slots[1] -= 1;
2272         } else {
2273                 btrfs_tree_unlock(left);
2274                 free_extent_buffer(left);
2275                 path->slots[0] -= push_items;
2276         }
2277         BUG_ON(path->slots[0] < 0);
2278         return ret;
2279 out:
2280         btrfs_tree_unlock(left);
2281         free_extent_buffer(left);
2282         return ret;
2283 }
2284
2285 /*
2286  * split the path's leaf in two, making sure there is at least data_size
2287  * available for the resulting leaf level of the path.
2288  *
2289  * returns 0 if all went well and < 0 on failure.
2290  */
2291 static noinline int split_leaf(struct btrfs_trans_handle *trans,
2292                                struct btrfs_root *root,
2293                                struct btrfs_key *ins_key,
2294                                struct btrfs_path *path, int data_size,
2295                                int extend)
2296 {
2297         u64 root_gen;
2298         struct extent_buffer *l;
2299         u32 nritems;
2300         int mid;
2301         int slot;
2302         struct extent_buffer *right;
2303         int space_needed = data_size + sizeof(struct btrfs_item);
2304         int data_copy_size;
2305         int rt_data_off;
2306         int i;
2307         int ret = 0;
2308         int wret;
2309         int double_split;
2310         int num_doubles = 0;
2311         struct btrfs_disk_key disk_key;
2312
2313         if (extend)
2314                 space_needed = data_size;
2315
2316         if (root->ref_cows)
2317                 root_gen = trans->transid;
2318         else
2319                 root_gen = 0;
2320
2321         /* first try to make some room by pushing left and right */
2322         if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
2323                 wret = push_leaf_right(trans, root, path, data_size, 0);
2324                 if (wret < 0) {
2325                         return wret;
2326                 }
2327                 if (wret) {
2328                         wret = push_leaf_left(trans, root, path, data_size, 0);
2329                         if (wret < 0)
2330                                 return wret;
2331                 }
2332                 l = path->nodes[0];
2333
2334                 /* did the pushes work? */
2335                 if (btrfs_leaf_free_space(root, l) >= space_needed)
2336                         return 0;
2337         }
2338
2339         if (!path->nodes[1]) {
2340                 ret = insert_new_root(trans, root, path, 1);
2341                 if (ret)
2342                         return ret;
2343         }
2344 again:
2345         double_split = 0;
2346         l = path->nodes[0];
2347         slot = path->slots[0];
2348         nritems = btrfs_header_nritems(l);
2349         mid = (nritems + 1)/ 2;
2350
2351         btrfs_item_key(l, &disk_key, 0);
2352
2353         right = btrfs_alloc_free_block(trans, root, root->leafsize,
2354                                          root->root_key.objectid,
2355                                          root_gen,
2356                                          le64_to_cpu(disk_key.objectid),
2357                                          0, l->start, 0);
2358         if (IS_ERR(right)) {
2359                 BUG_ON(1);
2360                 return PTR_ERR(right);
2361         }
2362
2363         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
2364         btrfs_set_header_bytenr(right, right->start);
2365         btrfs_set_header_generation(right, trans->transid);
2366         btrfs_set_header_owner(right, root->root_key.objectid);
2367         btrfs_set_header_level(right, 0);
2368         write_extent_buffer(right, root->fs_info->fsid,
2369                             (unsigned long)btrfs_header_fsid(right),
2370                             BTRFS_FSID_SIZE);
2371
2372         write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
2373                             (unsigned long)btrfs_header_chunk_tree_uuid(right),
2374                             BTRFS_UUID_SIZE);
2375         if (mid <= slot) {
2376                 if (nritems == 1 ||
2377                     leaf_space_used(l, mid, nritems - mid) + space_needed >
2378                         BTRFS_LEAF_DATA_SIZE(root)) {
2379                         if (slot >= nritems) {
2380                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
2381                                 btrfs_set_header_nritems(right, 0);
2382                                 wret = insert_ptr(trans, root, path,
2383                                                   &disk_key, right->start,
2384                                                   path->slots[1] + 1, 1);
2385                                 if (wret)
2386                                         ret = wret;
2387
2388                                 btrfs_tree_unlock(path->nodes[0]);
2389                                 free_extent_buffer(path->nodes[0]);
2390                                 path->nodes[0] = right;
2391                                 path->slots[0] = 0;
2392                                 path->slots[1] += 1;
2393                                 btrfs_mark_buffer_dirty(right);
2394                                 return ret;
2395                         }
2396                         mid = slot;
2397                         if (mid != nritems &&
2398                             leaf_space_used(l, mid, nritems - mid) +
2399                             space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
2400                                 double_split = 1;
2401                         }
2402                 }
2403         } else {
2404                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
2405                         BTRFS_LEAF_DATA_SIZE(root)) {
2406                         if (!extend && slot == 0) {
2407                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
2408                                 btrfs_set_header_nritems(right, 0);
2409                                 wret = insert_ptr(trans, root, path,
2410                                                   &disk_key,
2411                                                   right->start,
2412                                                   path->slots[1], 1);
2413                                 if (wret)
2414                                         ret = wret;
2415                                 btrfs_tree_unlock(path->nodes[0]);
2416                                 free_extent_buffer(path->nodes[0]);
2417                                 path->nodes[0] = right;
2418                                 path->slots[0] = 0;
2419                                 if (path->slots[1] == 0) {
2420                                         wret = fixup_low_keys(trans, root,
2421                                                    path, &disk_key, 1);
2422                                         if (wret)
2423                                                 ret = wret;
2424                                 }
2425                                 btrfs_mark_buffer_dirty(right);
2426                                 return ret;
2427                         } else if (extend && slot == 0) {
2428                                 mid = 1;
2429                         } else {
2430                                 mid = slot;
2431                                 if (mid != nritems &&
2432                                     leaf_space_used(l, mid, nritems - mid) +
2433                                     space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
2434                                         double_split = 1;
2435                                 }
2436                         }
2437                 }
2438         }
2439         nritems = nritems - mid;
2440         btrfs_set_header_nritems(right, nritems);
2441         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
2442
2443         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2444                            btrfs_item_nr_offset(mid),
2445                            nritems * sizeof(struct btrfs_item));
2446
2447         copy_extent_buffer(right, l,
2448                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2449                      data_copy_size, btrfs_leaf_data(l) +
2450                      leaf_data_end(root, l), data_copy_size);
2451
2452         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2453                       btrfs_item_end_nr(l, mid);
2454
2455         for (i = 0; i < nritems; i++) {
2456                 struct btrfs_item *item = btrfs_item_nr(right, i);
2457                 u32 ioff;
2458
2459                 if (!right->map_token) {
2460                         map_extent_buffer(right, (unsigned long)item,
2461                                         sizeof(struct btrfs_item),
2462                                         &right->map_token, &right->kaddr,
2463                                         &right->map_start, &right->map_len,
2464                                         KM_USER1);
2465                 }
2466
2467                 ioff = btrfs_item_offset(right, item);
2468                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2469         }
2470
2471         if (right->map_token) {
2472                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2473                 right->map_token = NULL;
2474         }
2475
2476         btrfs_set_header_nritems(l, mid);
2477         ret = 0;
2478         btrfs_item_key(right, &disk_key, 0);
2479         wret = insert_ptr(trans, root, path, &disk_key, right->start,
2480                           path->slots[1] + 1, 1);
2481         if (wret)
2482                 ret = wret;
2483
2484         btrfs_mark_buffer_dirty(right);
2485         btrfs_mark_buffer_dirty(l);
2486         BUG_ON(path->slots[0] != slot);
2487
2488         if (mid <= slot) {
2489                 btrfs_tree_unlock(path->nodes[0]);
2490                 free_extent_buffer(path->nodes[0]);
2491                 path->nodes[0] = right;
2492                 path->slots[0] -= mid;
2493                 path->slots[1] += 1;
2494         } else {
2495                 btrfs_tree_unlock(right);
2496                 free_extent_buffer(right);
2497         }
2498
2499         BUG_ON(path->slots[0] < 0);
2500
2501         if (double_split) {
2502                 BUG_ON(num_doubles != 0);
2503                 num_doubles++;
2504                 goto again;
2505         }
2506         return ret;
2507 }
2508
2509 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
2510                         struct btrfs_root *root,
2511                         struct btrfs_path *path,
2512                         u32 new_size, int from_end)
2513 {
2514         int ret = 0;
2515         int slot;
2516         int slot_orig;
2517         struct extent_buffer *leaf;
2518         struct btrfs_item *item;
2519         u32 nritems;
2520         unsigned int data_end;
2521         unsigned int old_data_start;
2522         unsigned int old_size;
2523         unsigned int size_diff;
2524         int i;
2525
2526         slot_orig = path->slots[0];
2527         leaf = path->nodes[0];
2528         slot = path->slots[0];
2529
2530         old_size = btrfs_item_size_nr(leaf, slot);
2531         if (old_size == new_size)
2532                 return 0;
2533
2534         nritems = btrfs_header_nritems(leaf);
2535         data_end = leaf_data_end(root, leaf);
2536
2537         old_data_start = btrfs_item_offset_nr(leaf, slot);
2538
2539         size_diff = old_size - new_size;
2540
2541         BUG_ON(slot < 0);
2542         BUG_ON(slot >= nritems);
2543
2544         /*
2545          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2546          */
2547         /* first correct the data pointers */
2548         for (i = slot; i < nritems; i++) {
2549                 u32 ioff;
2550                 item = btrfs_item_nr(leaf, i);
2551
2552                 if (!leaf->map_token) {
2553                         map_extent_buffer(leaf, (unsigned long)item,
2554                                         sizeof(struct btrfs_item),
2555                                         &leaf->map_token, &leaf->kaddr,
2556                                         &leaf->map_start, &leaf->map_len,
2557                                         KM_USER1);
2558                 }
2559
2560                 ioff = btrfs_item_offset(leaf, item);
2561                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2562         }
2563
2564         if (leaf->map_token) {
2565                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2566                 leaf->map_token = NULL;
2567         }
2568
2569         /* shift the data */
2570         if (from_end) {
2571                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2572                               data_end + size_diff, btrfs_leaf_data(leaf) +
2573                               data_end, old_data_start + new_size - data_end);
2574         } else {
2575                 struct btrfs_disk_key disk_key;
2576                 u64 offset;
2577
2578                 btrfs_item_key(leaf, &disk_key, slot);
2579
2580                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
2581                         unsigned long ptr;
2582                         struct btrfs_file_extent_item *fi;
2583
2584                         fi = btrfs_item_ptr(leaf, slot,
2585                                             struct btrfs_file_extent_item);
2586                         fi = (struct btrfs_file_extent_item *)(
2587                              (unsigned long)fi - size_diff);
2588
2589                         if (btrfs_file_extent_type(leaf, fi) ==
2590                             BTRFS_FILE_EXTENT_INLINE) {
2591                                 ptr = btrfs_item_ptr_offset(leaf, slot);
2592                                 memmove_extent_buffer(leaf, ptr,
2593                                         (unsigned long)fi,
2594                                         offsetof(struct btrfs_file_extent_item,
2595                                                  disk_bytenr));
2596                         }
2597                 }
2598
2599                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2600                               data_end + size_diff, btrfs_leaf_data(leaf) +
2601                               data_end, old_data_start - data_end);
2602
2603                 offset = btrfs_disk_key_offset(&disk_key);
2604                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
2605                 btrfs_set_item_key(leaf, &disk_key, slot);
2606                 if (slot == 0)
2607                         fixup_low_keys(trans, root, path, &disk_key, 1);
2608         }
2609
2610         item = btrfs_item_nr(leaf, slot);
2611         btrfs_set_item_size(leaf, item, new_size);
2612         btrfs_mark_buffer_dirty(leaf);
2613
2614         ret = 0;
2615         if (btrfs_leaf_free_space(root, leaf) < 0) {
2616                 btrfs_print_leaf(root, leaf);
2617                 BUG();
2618         }
2619         return ret;
2620 }
2621
2622 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2623                       struct btrfs_root *root, struct btrfs_path *path,
2624                       u32 data_size)
2625 {
2626         int ret = 0;
2627         int slot;
2628         int slot_orig;
2629         struct extent_buffer *leaf;
2630         struct btrfs_item *item;
2631         u32 nritems;
2632         unsigned int data_end;
2633         unsigned int old_data;
2634         unsigned int old_size;
2635         int i;
2636
2637         slot_orig = path->slots[0];
2638         leaf = path->nodes[0];
2639
2640         nritems = btrfs_header_nritems(leaf);
2641         data_end = leaf_data_end(root, leaf);
2642
2643         if (btrfs_leaf_free_space(root, leaf) < data_size) {
2644                 btrfs_print_leaf(root, leaf);
2645                 BUG();
2646         }
2647         slot = path->slots[0];
2648         old_data = btrfs_item_end_nr(leaf, slot);
2649
2650         BUG_ON(slot < 0);
2651         if (slot >= nritems) {
2652                 btrfs_print_leaf(root, leaf);
2653                 printk("slot %d too large, nritems %d\n", slot, nritems);
2654                 BUG_ON(1);
2655         }
2656
2657         /*
2658          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2659          */
2660         /* first correct the data pointers */
2661         for (i = slot; i < nritems; i++) {
2662                 u32 ioff;
2663                 item = btrfs_item_nr(leaf, i);
2664
2665                 if (!leaf->map_token) {
2666                         map_extent_buffer(leaf, (unsigned long)item,
2667                                         sizeof(struct btrfs_item),
2668                                         &leaf->map_token, &leaf->kaddr,
2669                                         &leaf->map_start, &leaf->map_len,
2670                                         KM_USER1);
2671                 }
2672                 ioff = btrfs_item_offset(leaf, item);
2673                 btrfs_set_item_offset(leaf, item, ioff - data_size);
2674         }
2675
2676         if (leaf->map_token) {
2677                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2678                 leaf->map_token = NULL;
2679         }
2680
2681         /* shift the data */
2682         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2683                       data_end - data_size, btrfs_leaf_data(leaf) +
2684                       data_end, old_data - data_end);
2685
2686         data_end = old_data;
2687         old_size = btrfs_item_size_nr(leaf, slot);
2688         item = btrfs_item_nr(leaf, slot);
2689         btrfs_set_item_size(leaf, item, old_size + data_size);
2690         btrfs_mark_buffer_dirty(leaf);
2691
2692         ret = 0;
2693         if (btrfs_leaf_free_space(root, leaf) < 0) {
2694                 btrfs_print_leaf(root, leaf);
2695                 BUG();
2696         }
2697         return ret;
2698 }
2699
2700 /*
2701  * Given a key and some data, insert an item into the tree.
2702  * This does all the path init required, making room in the tree if needed.
2703  */
2704 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
2705                             struct btrfs_root *root,
2706                             struct btrfs_path *path,
2707                             struct btrfs_key *cpu_key, u32 *data_size,
2708                             int nr)
2709 {
2710         struct extent_buffer *leaf;
2711         struct btrfs_item *item;
2712         int ret = 0;
2713         int slot;
2714         int slot_orig;
2715         int i;
2716         u32 nritems;
2717         u32 total_size = 0;
2718         u32 total_data = 0;
2719         unsigned int data_end;
2720         struct btrfs_disk_key disk_key;
2721
2722         for (i = 0; i < nr; i++) {
2723                 total_data += data_size[i];
2724         }
2725
2726         total_size = total_data + (nr * sizeof(struct btrfs_item));
2727         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
2728         if (ret == 0) {
2729                 return -EEXIST;
2730         }
2731         if (ret < 0)
2732                 goto out;
2733
2734         slot_orig = path->slots[0];
2735         leaf = path->nodes[0];
2736
2737         nritems = btrfs_header_nritems(leaf);
2738         data_end = leaf_data_end(root, leaf);
2739
2740         if (btrfs_leaf_free_space(root, leaf) <
2741             sizeof(struct btrfs_item) + total_size) {
2742                 btrfs_print_leaf(root, leaf);
2743                 printk("not enough freespace need %u have %d\n",
2744                        total_size, btrfs_leaf_free_space(root, leaf));
2745                 BUG();
2746         }
2747
2748         slot = path->slots[0];
2749         BUG_ON(slot < 0);
2750
2751         if (slot != nritems) {
2752                 int i;
2753                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2754
2755                 if (old_data < data_end) {
2756                         btrfs_print_leaf(root, leaf);
2757                         printk("slot %d old_data %d data_end %d\n",
2758                                slot, old_data, data_end);
2759                         BUG_ON(1);
2760                 }
2761                 /*
2762                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2763                  */
2764                 /* first correct the data pointers */
2765                 WARN_ON(leaf->map_token);
2766                 for (i = slot; i < nritems; i++) {
2767                         u32 ioff;
2768
2769                         item = btrfs_item_nr(leaf, i);
2770                         if (!leaf->map_token) {
2771                                 map_extent_buffer(leaf, (unsigned long)item,
2772                                         sizeof(struct btrfs_item),
2773                                         &leaf->map_token, &leaf->kaddr,
2774                                         &leaf->map_start, &leaf->map_len,
2775                                         KM_USER1);
2776                         }
2777
2778                         ioff = btrfs_item_offset(leaf, item);
2779                         btrfs_set_item_offset(leaf, item, ioff - total_data);
2780                 }
2781                 if (leaf->map_token) {
2782                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2783                         leaf->map_token = NULL;
2784                 }
2785
2786                 /* shift the items */
2787                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
2788                               btrfs_item_nr_offset(slot),
2789                               (nritems - slot) * sizeof(struct btrfs_item));
2790
2791                 /* shift the data */
2792                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2793                               data_end - total_data, btrfs_leaf_data(leaf) +
2794                               data_end, old_data - data_end);
2795                 data_end = old_data;
2796         }
2797
2798         /* setup the item for the new data */
2799         for (i = 0; i < nr; i++) {
2800                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
2801                 btrfs_set_item_key(leaf, &disk_key, slot + i);
2802                 item = btrfs_item_nr(leaf, slot + i);
2803                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
2804                 data_end -= data_size[i];
2805                 btrfs_set_item_size(leaf, item, data_size[i]);
2806         }
2807         btrfs_set_header_nritems(leaf, nritems + nr);
2808         btrfs_mark_buffer_dirty(leaf);
2809
2810         ret = 0;
2811         if (slot == 0) {
2812                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2813                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2814         }
2815
2816         if (btrfs_leaf_free_space(root, leaf) < 0) {
2817                 btrfs_print_leaf(root, leaf);
2818                 BUG();
2819         }
2820 out:
2821         return ret;
2822 }
2823
2824 /*
2825  * Given a key and some data, insert an item into the tree.
2826  * This does all the path init required, making room in the tree if needed.
2827  */
2828 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2829                       *root, struct btrfs_key *cpu_key, void *data, u32
2830                       data_size)
2831 {
2832         int ret = 0;
2833         struct btrfs_path *path;
2834         struct extent_buffer *leaf;
2835         unsigned long ptr;
2836
2837         path = btrfs_alloc_path();
2838         BUG_ON(!path);
2839         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2840         if (!ret) {
2841                 leaf = path->nodes[0];
2842                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2843                 write_extent_buffer(leaf, data, ptr, data_size);
2844                 btrfs_mark_buffer_dirty(leaf);
2845         }
2846         btrfs_free_path(path);
2847         return ret;
2848 }
2849
2850 /*
2851  * delete the pointer from a given node.
2852  *
2853  * If the delete empties a node, the node is removed from the tree,
2854  * continuing all the way the root if required.  The root is converted into
2855  * a leaf if all the nodes are emptied.
2856  */
2857 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2858                    struct btrfs_path *path, int level, int slot)
2859 {
2860         struct extent_buffer *parent = path->nodes[level];
2861         u32 nritems;
2862         int ret = 0;
2863         int wret;
2864
2865         nritems = btrfs_header_nritems(parent);
2866         if (slot != nritems -1) {
2867                 memmove_extent_buffer(parent,
2868                               btrfs_node_key_ptr_offset(slot),
2869                               btrfs_node_key_ptr_offset(slot + 1),
2870                               sizeof(struct btrfs_key_ptr) *
2871                               (nritems - slot - 1));
2872         }
2873         nritems--;
2874         btrfs_set_header_nritems(parent, nritems);
2875         if (nritems == 0 && parent == root->node) {
2876                 BUG_ON(btrfs_header_level(root->node) != 1);
2877                 /* just turn the root into a leaf and break */
2878                 btrfs_set_header_level(root->node, 0);
2879         } else if (slot == 0) {
2880                 struct btrfs_disk_key disk_key;
2881
2882                 btrfs_node_key(parent, &disk_key, 0);
2883                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2884                 if (wret)
2885                         ret = wret;
2886         }
2887         btrfs_mark_buffer_dirty(parent);
2888         return ret;
2889 }
2890
2891 /*
2892  * delete the item at the leaf level in path.  If that empties
2893  * the leaf, remove it from the tree
2894  */
2895 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2896                     struct btrfs_path *path, int slot, int nr)
2897 {
2898         struct extent_buffer *leaf;
2899         struct btrfs_item *item;
2900         int last_off;
2901         int dsize = 0;
2902         int ret = 0;
2903         int wret;
2904         int i;
2905         u32 nritems;
2906
2907         leaf = path->nodes[0];
2908         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
2909
2910         for (i = 0; i < nr; i++)
2911                 dsize += btrfs_item_size_nr(leaf, slot + i);
2912
2913         nritems = btrfs_header_nritems(leaf);
2914
2915         if (slot + nr != nritems) {
2916                 int i;
2917                 int data_end = leaf_data_end(root, leaf);
2918
2919                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2920                               data_end + dsize,
2921                               btrfs_leaf_data(leaf) + data_end,
2922                               last_off - data_end);
2923
2924                 for (i = slot + nr; i < nritems; i++) {
2925                         u32 ioff;
2926
2927                         item = btrfs_item_nr(leaf, i);
2928                         if (!leaf->map_token) {
2929                                 map_extent_buffer(leaf, (unsigned long)item,
2930                                         sizeof(struct btrfs_item),
2931                                         &leaf->map_token, &leaf->kaddr,
2932                                         &leaf->map_start, &leaf->map_len,
2933                                         KM_USER1);
2934                         }
2935                         ioff = btrfs_item_offset(leaf, item);
2936                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2937                 }
2938
2939                 if (leaf->map_token) {
2940                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2941                         leaf->map_token = NULL;
2942                 }
2943
2944                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2945                               btrfs_item_nr_offset(slot + nr),
2946                               sizeof(struct btrfs_item) *
2947                               (nritems - slot - nr));
2948         }
2949         btrfs_set_header_nritems(leaf, nritems - nr);
2950         nritems -= nr;
2951
2952         /* delete the leaf if we've emptied it */
2953         if (nritems == 0) {
2954                 if (leaf == root->node) {
2955                         btrfs_set_header_level(leaf, 0);
2956                 } else {
2957                         u64 root_gen = btrfs_header_generation(path->nodes[1]);
2958                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
2959                         if (wret)
2960                                 ret = wret;
2961                         wret = btrfs_free_extent(trans, root,
2962                                          leaf->start, leaf->len,
2963                                          btrfs_header_owner(path->nodes[1]),
2964                                          root_gen, 0, 0, 1);
2965                         if (wret)
2966                                 ret = wret;
2967                 }
2968         } else {
2969                 int used = leaf_space_used(leaf, 0, nritems);
2970                 if (slot == 0) {
2971                         struct btrfs_disk_key disk_key;
2972
2973                         btrfs_item_key(leaf, &disk_key, 0);
2974                         wret = fixup_low_keys(trans, root, path,
2975                                               &disk_key, 1);
2976                         if (wret)
2977                                 ret = wret;
2978                 }
2979
2980                 /* delete the leaf if it is mostly empty */
2981                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 4) {
2982                         /* push_leaf_left fixes the path.
2983                          * make sure the path still points to our leaf
2984                          * for possible call to del_ptr below
2985                          */
2986                         slot = path->slots[1];
2987                         extent_buffer_get(leaf);
2988
2989                         wret = push_leaf_left(trans, root, path, 1, 1);
2990                         if (wret < 0 && wret != -ENOSPC)
2991                                 ret = wret;
2992
2993                         if (path->nodes[0] == leaf &&
2994                             btrfs_header_nritems(leaf)) {
2995                                 wret = push_leaf_right(trans, root, path, 1, 1);
2996                                 if (wret < 0 && wret != -ENOSPC)
2997                                         ret = wret;
2998                         }
2999
3000                         if (btrfs_header_nritems(leaf) == 0) {
3001                                 u64 root_gen;
3002                                 u64 bytenr = leaf->start;
3003                                 u32 blocksize = leaf->len;
3004
3005                                 root_gen = btrfs_header_generation(
3006                                                            path->nodes[1]);
3007
3008                                 wret = del_ptr(trans, root, path, 1, slot);
3009                                 if (wret)
3010                                         ret = wret;
3011
3012                                 free_extent_buffer(leaf);
3013                                 wret = btrfs_free_extent(trans, root, bytenr,
3014                                              blocksize,
3015                                              btrfs_header_owner(path->nodes[1]),
3016                                              root_gen, 0, 0, 1);
3017                                 if (wret)
3018                                         ret = wret;
3019                         } else {
3020                                 /* if we're still in the path, make sure
3021                                  * we're dirty.  Otherwise, one of the
3022                                  * push_leaf functions must have already
3023                                  * dirtied this buffer
3024                                  */
3025                                 if (path->nodes[0] == leaf)
3026                                         btrfs_mark_buffer_dirty(leaf);
3027                                 free_extent_buffer(leaf);
3028                         }
3029                 } else {
3030                         btrfs_mark_buffer_dirty(leaf);
3031                 }
3032         }
3033         return ret;
3034 }
3035
3036 /*
3037  * search the tree again to find a leaf with lesser keys
3038  * returns 0 if it found something or 1 if there are no lesser leaves.
3039  * returns < 0 on io errors.
3040  */
3041 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
3042 {
3043         struct btrfs_key key;
3044         struct btrfs_disk_key found_key;
3045         int ret;
3046
3047         btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
3048
3049         if (key.offset > 0)
3050                 key.offset--;
3051         else if (key.type > 0)
3052                 key.type--;
3053         else if (key.objectid > 0)
3054                 key.objectid--;
3055         else
3056                 return 1;
3057
3058         btrfs_release_path(root, path);
3059         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3060         if (ret < 0)
3061                 return ret;
3062         btrfs_item_key(path->nodes[0], &found_key, 0);
3063         ret = comp_keys(&found_key, &key);
3064         if (ret < 0)
3065                 return 0;
3066         return 1;
3067 }
3068
3069 /*
3070  * A helper function to walk down the tree starting at min_key, and looking
3071  * for nodes or leaves that are either in cache or have a minimum
3072  * transaction id.  This is used by the btree defrag code, but could
3073  * also be used to search for blocks that have changed since a given
3074  * transaction id.
3075  *
3076  * This does not cow, but it does stuff the starting key it finds back
3077  * into min_key, so you can call btrfs_search_slot with cow=1 on the
3078  * key and get a writable path.
3079  *
3080  * This does lock as it descends, and path->keep_locks should be set
3081  * to 1 by the caller.
3082  *
3083  * This honors path->lowest_level to prevent descent past a given level
3084  * of the tree.
3085  *
3086  * returns zero if something useful was found, < 0 on error and 1 if there
3087  * was nothing in the tree that matched the search criteria.
3088  */
3089 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
3090                          struct btrfs_key *max_key,
3091                          struct btrfs_path *path, int cache_only,
3092                          u64 min_trans)
3093 {
3094         struct extent_buffer *cur;
3095         struct btrfs_key found_key;
3096         int slot;
3097         int sret;
3098         u32 nritems;
3099         int level;
3100         int ret = 1;
3101
3102 again:
3103         cur = btrfs_lock_root_node(root);
3104         level = btrfs_header_level(cur);
3105         WARN_ON(path->nodes[level]);
3106         path->nodes[level] = cur;
3107         path->locks[level] = 1;
3108
3109         if (btrfs_header_generation(cur) < min_trans) {
3110                 ret = 1;
3111                 goto out;
3112         }
3113         while(1) {
3114                 nritems = btrfs_header_nritems(cur);
3115                 level = btrfs_header_level(cur);
3116                 sret = bin_search(cur, min_key, level, &slot);
3117
3118                 /* at level = 0, we're done, setup the path and exit */
3119                 if (level == 0) {
3120                         if (slot >= nritems)
3121                                 goto find_next_key;
3122                         ret = 0;
3123                         path->slots[level] = slot;
3124                         btrfs_item_key_to_cpu(cur, &found_key, slot);
3125                         goto out;
3126                 }
3127                 if (sret && slot > 0)
3128                         slot--;
3129                 /*
3130                  * check this node pointer against the cache_only and
3131                  * min_trans parameters.  If it isn't in cache or is too
3132                  * old, skip to the next one.
3133                  */
3134                 while(slot < nritems) {
3135                         u64 blockptr;
3136                         u64 gen;
3137                         struct extent_buffer *tmp;
3138                         struct btrfs_disk_key disk_key;
3139
3140                         blockptr = btrfs_node_blockptr(cur, slot);
3141                         gen = btrfs_node_ptr_generation(cur, slot);
3142                         if (gen < min_trans) {
3143                                 slot++;
3144                                 continue;
3145                         }
3146                         if (!cache_only)
3147                                 break;
3148
3149                         if (max_key) {
3150                                 btrfs_node_key(cur, &disk_key, slot);
3151                                 if (comp_keys(&disk_key, max_key) >= 0) {
3152                                         ret = 1;
3153                                         goto out;
3154                                 }
3155                         }
3156
3157                         tmp = btrfs_find_tree_block(root, blockptr,
3158                                             btrfs_level_size(root, level - 1));
3159
3160                         if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
3161                                 free_extent_buffer(tmp);
3162                                 break;
3163                         }
3164                         if (tmp)
3165                                 free_extent_buffer(tmp);
3166                         slot++;
3167                 }
3168 find_next_key:
3169                 /*
3170                  * we didn't find a candidate key in this node, walk forward
3171                  * and find another one
3172                  */
3173                 if (slot >= nritems) {
3174                         path->slots[level] = slot;
3175                         sret = btrfs_find_next_key(root, path, min_key, level,
3176                                                   cache_only, min_trans);
3177                         if (sret == 0) {
3178                                 btrfs_release_path(root, path);
3179                                 goto again;
3180                         } else {
3181                                 goto out;
3182                         }
3183                 }
3184                 /* save our key for returning back */
3185                 btrfs_node_key_to_cpu(cur, &found_key, slot);
3186                 path->slots[level] = slot;
3187                 if (level == path->lowest_level) {
3188                         ret = 0;
3189                         unlock_up(path, level, 1);
3190                         goto out;
3191                 }
3192                 cur = read_node_slot(root, cur, slot);
3193
3194                 btrfs_tree_lock(cur);
3195                 path->locks[level - 1] = 1;
3196                 path->nodes[level - 1] = cur;
3197                 unlock_up(path, level, 1);
3198         }
3199 out:
3200         if (ret == 0)
3201                 memcpy(min_key, &found_key, sizeof(found_key));
3202         return ret;
3203 }
3204
3205 /*
3206  * this is similar to btrfs_next_leaf, but does not try to preserve
3207  * and fixup the path.  It looks for and returns the next key in the
3208  * tree based on the current path and the cache_only and min_trans
3209  * parameters.
3210  *
3211  * 0 is returned if another key is found, < 0 if there are any errors
3212  * and 1 is returned if there are no higher keys in the tree
3213  *
3214  * path->keep_locks should be set to 1 on the search made before
3215  * calling this function.
3216  */
3217 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
3218                         struct btrfs_key *key, int lowest_level,
3219                         int cache_only, u64 min_trans)
3220 {
3221         int level = lowest_level;
3222         int slot;
3223         struct extent_buffer *c;
3224
3225         while(level < BTRFS_MAX_LEVEL) {
3226                 if (!path->nodes[level])
3227                         return 1;
3228
3229                 slot = path->slots[level] + 1;
3230                 c = path->nodes[level];
3231 next:
3232                 if (slot >= btrfs_header_nritems(c)) {
3233                         level++;
3234                         if (level == BTRFS_MAX_LEVEL) {
3235                                 return 1;
3236                         }
3237                         continue;
3238                 }
3239                 if (level == 0)
3240                         btrfs_item_key_to_cpu(c, key, slot);
3241                 else {
3242                         u64 blockptr = btrfs_node_blockptr(c, slot);
3243                         u64 gen = btrfs_node_ptr_generation(c, slot);
3244
3245                         if (cache_only) {
3246                                 struct extent_buffer *cur;
3247                                 cur = btrfs_find_tree_block(root, blockptr,
3248                                             btrfs_level_size(root, level - 1));
3249                                 if (!cur || !btrfs_buffer_uptodate(cur, gen)) {
3250                                         slot++;
3251                                         if (cur)
3252                                                 free_extent_buffer(cur);
3253                                         goto next;
3254                                 }
3255                                 free_extent_buffer(cur);
3256                         }
3257                         if (gen < min_trans) {
3258                                 slot++;
3259                                 goto next;
3260                         }
3261                         btrfs_node_key_to_cpu(c, key, slot);
3262                 }
3263                 return 0;
3264         }
3265         return 1;
3266 }
3267
3268 /*
3269  * search the tree again to find a leaf with greater keys
3270  * returns 0 if it found something or 1 if there are no greater leaves.
3271  * returns < 0 on io errors.
3272  */
3273 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
3274 {
3275         int slot;
3276         int level = 1;
3277         struct extent_buffer *c;
3278         struct extent_buffer *next = NULL;
3279         struct btrfs_key key;
3280         u32 nritems;
3281         int ret;
3282
3283         nritems = btrfs_header_nritems(path->nodes[0]);
3284         if (nritems == 0) {
3285                 return 1;
3286         }
3287
3288         btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
3289
3290         btrfs_release_path(root, path);
3291         path->keep_locks = 1;
3292         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3293         path->keep_locks = 0;
3294
3295         if (ret < 0)
3296                 return ret;
3297
3298         nritems = btrfs_header_nritems(path->nodes[0]);
3299         /*
3300          * by releasing the path above we dropped all our locks.  A balance
3301          * could have added more items next to the key that used to be
3302          * at the very end of the block.  So, check again here and
3303          * advance the path if there are now more items available.
3304          */
3305         if (nritems > 0 && path->slots[0] < nritems - 1) {
3306                 path->slots[0]++;
3307                 goto done;
3308         }
3309
3310         while(level < BTRFS_MAX_LEVEL) {
3311                 if (!path->nodes[level])
3312                         return 1;
3313
3314                 slot = path->slots[level] + 1;
3315                 c = path->nodes[level];
3316                 if (slot >= btrfs_header_nritems(c)) {
3317                         level++;
3318                         if (level == BTRFS_MAX_LEVEL) {
3319                                 return 1;
3320                         }
3321                         continue;
3322                 }
3323
3324                 if (next) {
3325                         btrfs_tree_unlock(next);
3326                         free_extent_buffer(next);
3327                 }
3328
3329                 if (level == 1 && (path->locks[1] || path->skip_locking) &&
3330                     path->reada)
3331                         reada_for_search(root, path, level, slot, 0);
3332
3333                 next = read_node_slot(root, c, slot);
3334                 if (!path->skip_locking) {
3335                         WARN_ON(!btrfs_tree_locked(c));
3336                         btrfs_tree_lock(next);
3337                 }
3338                 break;
3339         }
3340         path->slots[level] = slot;
3341         while(1) {
3342                 level--;
3343                 c = path->nodes[level];
3344                 if (path->locks[level])
3345                         btrfs_tree_unlock(c);
3346                 free_extent_buffer(c);
3347                 path->nodes[level] = next;
3348                 path->slots[level] = 0;
3349                 if (!path->skip_locking)
3350                         path->locks[level] = 1;
3351                 if (!level)
3352                         break;
3353                 if (level == 1 && path->locks[1] && path->reada)
3354                         reada_for_search(root, path, level, slot, 0);
3355                 next = read_node_slot(root, next, 0);
3356                 if (!path->skip_locking) {
3357                         WARN_ON(!btrfs_tree_locked(path->nodes[level]));
3358                         btrfs_tree_lock(next);
3359                 }
3360         }
3361 done:
3362         unlock_up(path, 0, 1);
3363         return 0;
3364 }
3365
3366 /*
3367  * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
3368  * searching until it gets past min_objectid or finds an item of 'type'
3369  *
3370  * returns 0 if something is found, 1 if nothing was found and < 0 on error
3371  */
3372 int btrfs_previous_item(struct btrfs_root *root,
3373                         struct btrfs_path *path, u64 min_objectid,
3374                         int type)
3375 {
3376         struct btrfs_key found_key;
3377         struct extent_buffer *leaf;
3378         u32 nritems;
3379         int ret;
3380
3381         while(1) {
3382                 if (path->slots[0] == 0) {
3383                         ret = btrfs_prev_leaf(root, path);
3384                         if (ret != 0)
3385                                 return ret;
3386                 } else {
3387                         path->slots[0]--;
3388                 }
3389                 leaf = path->nodes[0];
3390                 nritems = btrfs_header_nritems(leaf);
3391                 if (nritems == 0)
3392                         return 1;
3393                 if (path->slots[0] == nritems)
3394                         path->slots[0]--;
3395
3396                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
3397                 if (found_key.type == type)
3398                         return 0;
3399                 if (found_key.objectid < min_objectid)
3400                         break;
3401                 if (found_key.objectid == min_objectid &&
3402                     found_key.type < type)
3403                         break;
3404         }
3405         return 1;
3406 }