fs/btrfs/ctree.c

   1 /*
   2  * Copyright (C) 2007,2008 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 static int setup_items_for_insert(struct btrfs_trans_handle *trans,
  41                         struct btrfs_root *root, struct btrfs_path *path,
  42                         struct btrfs_key *cpu_key, u32 *data_size,
  43                         u32 total_data, u32 total_size, int nr);
  44
  45
  46 struct btrfs_path *btrfs_alloc_path(void)
  47 {
  48         struct btrfs_path *path;
  49         path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
  50         if (path)
  51                 path->reada = 1;
  52         return path;
  53 }
  54
  55 /*
  56  * set all locked nodes in the path to blocking locks.  This should
  57  * be done before scheduling
  58  */
  59 noinline void btrfs_set_path_blocking(struct btrfs_path *p)
  60 {
  61         int i;
  62         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  63                 if (p->nodes[i] && p->locks[i])
  64                         btrfs_set_lock_blocking(p->nodes[i]);
  65         }
  66 }
  67
  68 /*
  69  * reset all the locked nodes in the patch to spinning locks.
  70  *
  71  * held is used to keep lockdep happy, when lockdep is enabled
  72  * we set held to a blocking lock before we go around and
  73  * retake all the spinlocks in the path.  You can safely use NULL
  74  * for held
  75  */
  76 noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
  77                                         struct extent_buffer *held)
  78 {
  79         int i;
  80
  81 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  82         /* lockdep really cares that we take all of these spinlocks
  83          * in the right order.  If any of the locks in the path are not
  84          * currently blocking, it is going to complain.  So, make really
  85          * really sure by forcing the path to blocking before we clear
  86          * the path blocking.
  87          */
  88         if (held)
  89                 btrfs_set_lock_blocking(held);
  90         btrfs_set_path_blocking(p);
  91 #endif
  92
  93         for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
  94                 if (p->nodes[i] && p->locks[i])
  95                         btrfs_clear_lock_blocking(p->nodes[i]);
  96         }
  97
  98 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  99         if (held)
 100                 btrfs_clear_lock_blocking(held);
 101 #endif
 102 }
 103
 104 /* this also releases the path */
 105 void btrfs_free_path(struct btrfs_path *p)
 106 {
 107         btrfs_release_path(NULL, p);
 108         kmem_cache_free(btrfs_path_cachep, p);
 109 }
 110
 111 /*
 112  * path release drops references on the extent buffers in the path
 113  * and it drops any locks held by this path
 114  *
 115  * It is safe to call this on paths that no locks or extent buffers held.
 116  */
 117 noinline void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
 118 {
 119         int i;
 120
 121         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
 122                 p->slots[i] = 0;
 123                 if (!p->nodes[i])
 124                         continue;
 125                 if (p->locks[i]) {
 126                         btrfs_tree_unlock(p->nodes[i]);
 127                         p->locks[i] = 0;
 128                 }
 129                 free_extent_buffer(p->nodes[i]);
 130                 p->nodes[i] = NULL;
 131         }
 132 }
 133
 134 /*
 135  * safely gets a reference on the root node of a tree.  A lock
 136  * is not taken, so a concurrent writer may put a different node
 137  * at the root of the tree.  See btrfs_lock_root_node for the
 138  * looping required.
 139  *
 140  * The extent buffer returned by this has a reference taken, so
 141  * it won't disappear.  It may stop being the root of the tree
 142  * at any time because there are no locks held.
 143  */
 144 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
 145 {
 146         struct extent_buffer *eb;
 147         spin_lock(&root->node_lock);
 148         eb = root->node;
 149         extent_buffer_get(eb);
 150         spin_unlock(&root->node_lock);
 151         return eb;
 152 }
 153
 154 /* loop around taking references on and locking the root node of the
 155  * tree until you end up with a lock on the root.  A locked buffer
 156  * is returned, with a reference held.
 157  */
 158 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
 159 {
 160         struct extent_buffer *eb;
 161
 162         while (1) {
 163                 eb = btrfs_root_node(root);
 164                 btrfs_tree_lock(eb);
 165
 166                 spin_lock(&root->node_lock);
 167                 if (eb == root->node) {
 168                         spin_unlock(&root->node_lock);
 169                         break;
 170                 }
 171                 spin_unlock(&root->node_lock);
 172
 173                 btrfs_tree_unlock(eb);
 174                 free_extent_buffer(eb);
 175         }
 176         return eb;
 177 }
 178
 179 /* cowonly root (everything not a reference counted cow subvolume), just get
 180  * put onto a simple dirty list.  transaction.c walks this to make sure they
 181  * get properly updated on disk.
 182  */
 183 static void add_root_to_dirty_list(struct btrfs_root *root)
 184 {
 185         if (root->track_dirty && list_empty(&root->dirty_list)) {
 186                 list_add(&root->dirty_list,
 187                          &root->fs_info->dirty_cowonly_roots);
 188         }
 189 }
 190
 191 /*
 192  * used by snapshot creation to make a copy of a root for a tree with
 193  * a given objectid.  The buffer with the new root node is returned in
 194  * cow_ret, and this func returns zero on success or a negative error code.
 195  */
 196 int btrfs_copy_root(struct btrfs_trans_handle *trans,
 197                       struct btrfs_root *root,
 198                       struct extent_buffer *buf,
 199                       struct extent_buffer **cow_ret, u64 new_root_objectid)
 200 {
 201         struct extent_buffer *cow;
 202         u32 nritems;
 203         int ret = 0;
 204         int level;
 205         struct btrfs_disk_key disk_key;
 206
 207         WARN_ON(root->ref_cows && trans->transid !=
 208                 root->fs_info->running_transaction->transid);
 209         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 210
 211         level = btrfs_header_level(buf);
 212         nritems = btrfs_header_nritems(buf);
 213         if (level == 0)
 214                 btrfs_item_key(buf, &disk_key, 0);
 215         else
 216                 btrfs_node_key(buf, &disk_key, 0);
 217
 218         cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
 219                                      new_root_objectid, &disk_key, level,
 220                                      buf->start, 0);
 221         if (IS_ERR(cow))
 222                 return PTR_ERR(cow);
 223
 224         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 225         btrfs_set_header_bytenr(cow, cow->start);
 226         btrfs_set_header_generation(cow, trans->transid);
 227         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 228         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 229                                      BTRFS_HEADER_FLAG_RELOC);
 230         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 231                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 232         else
 233                 btrfs_set_header_owner(cow, new_root_objectid);
 234
 235         write_extent_buffer(cow, root->fs_info->fsid,
 236                             (unsigned long)btrfs_header_fsid(cow),
 237                             BTRFS_FSID_SIZE);
 238
 239         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 240         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 241                 ret = btrfs_inc_ref(trans, root, cow, 1);
 242         else
 243                 ret = btrfs_inc_ref(trans, root, cow, 0);
 244
 245         if (ret)
 246                 return ret;
 247
 248         btrfs_mark_buffer_dirty(cow);
 249         *cow_ret = cow;
 250         return 0;
 251 }
 252
 253 /*
 254  * check if the tree block can be shared by multiple trees
 255  */
 256 int btrfs_block_can_be_shared(struct btrfs_root *root,
 257                               struct extent_buffer *buf)
 258 {
 259         /*
 260          * Tree blocks not in refernece counted trees and tree roots
 261          * are never shared. If a block was allocated after the last
 262          * snapshot and the block was not allocated by tree relocation,
 263          * we know the block is not shared.
 264          */
 265         if (root->ref_cows &&
 266             buf != root->node && buf != root->commit_root &&
 267             (btrfs_header_generation(buf) <=
 268              btrfs_root_last_snapshot(&root->root_item) ||
 269              btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 270                 return 1;
 271 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 272         if (root->ref_cows &&
 273             btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 274                 return 1;
 275 #endif
 276         return 0;
 277 }
 278
 279 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 280                                        struct btrfs_root *root,
 281                                        struct extent_buffer *buf,
 282                                        struct extent_buffer *cow)
 283 {
 284         u64 refs;
 285         u64 owner;
 286         u64 flags;
 287         u64 new_flags = 0;
 288         int ret;
 289
 290         /*
 291          * Backrefs update rules:
 292          *
 293          * Always use full backrefs for extent pointers in tree block
 294          * allocated by tree relocation.
 295          *
 296          * If a shared tree block is no longer referenced by its owner
 297          * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 298          * use full backrefs for extent pointers in tree block.
 299          *
 300          * If a tree block is been relocating
 301          * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
 302          * use full backrefs for extent pointers in tree block.
 303          * The reason for this is some operations (such as drop tree)
 304          * are only allowed for blocks use full backrefs.
 305          */
 306
 307         if (btrfs_block_can_be_shared(root, buf)) {
 308                 ret = btrfs_lookup_extent_info(trans, root, buf->start,
 309                                                buf->len, &refs, &flags);
 310                 BUG_ON(ret);
 311                 BUG_ON(refs == 0);
 312         } else {
 313                 refs = 1;
 314                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 315                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 316                         flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
 317                 else
 318                         flags = 0;
 319         }
 320
 321         owner = btrfs_header_owner(buf);
 322         BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
 323                !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
 324
 325         if (refs > 1) {
 326                 if ((owner == root->root_key.objectid ||
 327                      root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 328                     !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 329                         ret = btrfs_inc_ref(trans, root, buf, 1);
 330                         BUG_ON(ret);
 331
 332                         if (root->root_key.objectid ==
 333                             BTRFS_TREE_RELOC_OBJECTID) {
 334                                 ret = btrfs_dec_ref(trans, root, buf, 0);
 335                                 BUG_ON(ret);
 336                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 337                                 BUG_ON(ret);
 338                         }
 339                         new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 340                 } else {
 341
 342                         if (root->root_key.objectid ==
 343                             BTRFS_TREE_RELOC_OBJECTID)
 344                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 345                         else
 346                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 347                         BUG_ON(ret);
 348                 }
 349                 if (new_flags != 0) {
 350                         ret = btrfs_set_disk_extent_flags(trans, root,
 351                                                           buf->start,
 352                                                           buf->len,
 353                                                           new_flags, 0);
 354                         BUG_ON(ret);
 355                 }
 356         } else {
 357                 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
 358                         if (root->root_key.objectid ==
 359                             BTRFS_TREE_RELOC_OBJECTID)
 360                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 361                         else
 362                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 363                         BUG_ON(ret);
 364                         ret = btrfs_dec_ref(trans, root, buf, 1);
 365                         BUG_ON(ret);
 366                 }
 367                 clean_tree_block(trans, root, buf);
 368         }
 369         return 0;
 370 }
 371
 372 /*
 373  * does the dirty work in cow of a single block.  The parent block (if
 374  * supplied) is updated to point to the new cow copy.  The new buffer is marked
 375  * dirty and returned locked.  If you modify the block it needs to be marked
 376  * dirty again.
 377  *
 378  * search_start -- an allocation hint for the new block
 379  *
 380  * empty_size -- a hint that you plan on doing more cow.  This is the size in
 381  * bytes the allocator should try to find free next to the block it returns.
 382  * This is just a hint and may be ignored by the allocator.
 383  */
 384 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 385                              struct btrfs_root *root,
 386                              struct extent_buffer *buf,
 387                              struct extent_buffer *parent, int parent_slot,
 388                              struct extent_buffer **cow_ret,
 389                              u64 search_start, u64 empty_size)
 390 {
 391         struct btrfs_disk_key disk_key;
 392         struct extent_buffer *cow;
 393         int level;
 394         int unlock_orig = 0;
 395         u64 parent_start;
 396
 397         if (*cow_ret == buf)
 398                 unlock_orig = 1;
 399
 400         btrfs_assert_tree_locked(buf);
 401
 402         WARN_ON(root->ref_cows && trans->transid !=
 403                 root->fs_info->running_transaction->transid);
 404         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 405
 406         level = btrfs_header_level(buf);
 407
 408         if (level == 0)
 409                 btrfs_item_key(buf, &disk_key, 0);
 410         else
 411                 btrfs_node_key(buf, &disk_key, 0);
 412
 413         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
 414                 if (parent)
 415                         parent_start = parent->start;
 416                 else
 417                         parent_start = 0;
 418         } else
 419                 parent_start = 0;
 420
 421         cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
 422                                      root->root_key.objectid, &disk_key,
 423                                      level, search_start, empty_size);
 424         if (IS_ERR(cow))
 425                 return PTR_ERR(cow);
 426
 427         /* cow is set to blocking by btrfs_init_new_buffer */
 428
 429         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 430         btrfs_set_header_bytenr(cow, cow->start);
 431         btrfs_set_header_generation(cow, trans->transid);
 432         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 433         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 434                                      BTRFS_HEADER_FLAG_RELOC);
 435         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 436                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 437         else
 438                 btrfs_set_header_owner(cow, root->root_key.objectid);
 439
 440         write_extent_buffer(cow, root->fs_info->fsid,
 441                             (unsigned long)btrfs_header_fsid(cow),
 442                             BTRFS_FSID_SIZE);
 443
 444         update_ref_for_cow(trans, root, buf, cow);
 445
 446         if (buf == root->node) {
 447                 WARN_ON(parent && parent != buf);
 448                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 449                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 450                         parent_start = buf->start;
 451                 else
 452                         parent_start = 0;
 453
 454                 spin_lock(&root->node_lock);
 455                 root->node = cow;
 456                 extent_buffer_get(cow);
 457                 spin_unlock(&root->node_lock);
 458
 459                 btrfs_free_tree_block(trans, root, buf->start, buf->len,
 460                                 parent_start, root->root_key.objectid, level);
 461                 free_extent_buffer(buf);
 462                 add_root_to_dirty_list(root);
 463         } else {
 464                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 465                         parent_start = parent->start;
 466                 else
 467                         parent_start = 0;
 468
 469                 WARN_ON(trans->transid != btrfs_header_generation(parent));
 470                 btrfs_set_node_blockptr(parent, parent_slot,
 471                                         cow->start);
 472                 btrfs_set_node_ptr_generation(parent, parent_slot,
 473                                               trans->transid);
 474                 btrfs_mark_buffer_dirty(parent);
 475                 btrfs_free_tree_block(trans, root, buf->start, buf->len,
 476                                 parent_start, root->root_key.objectid, level);
 477         }
 478         if (unlock_orig)
 479                 btrfs_tree_unlock(buf);
 480         free_extent_buffer(buf);
 481         btrfs_mark_buffer_dirty(cow);
 482         *cow_ret = cow;
 483         return 0;
 484 }
 485
 486 static inline int should_cow_block(struct btrfs_trans_handle *trans,
 487                                    struct btrfs_root *root,
 488                                    struct extent_buffer *buf)
 489 {
 490         if (btrfs_header_generation(buf) == trans->transid &&
 491             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
 492             !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
 493               btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 494                 return 0;
 495         return 1;
 496 }
 497
 498 /*
 499  * cows a single block, see __btrfs_cow_block for the real work.
 500  * This version of it has extra checks so that a block isn't cow'd more than
 501  * once per transaction, as long as it hasn't been written yet
 502  */
 503 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
 504                     struct btrfs_root *root, struct extent_buffer *buf,
 505                     struct extent_buffer *parent, int parent_slot,
 506                     struct extent_buffer **cow_ret)
 507 {
 508         u64 search_start;
 509         int ret;
 510
 511         if (trans->transaction != root->fs_info->running_transaction) {
 512                 printk(KERN_CRIT "trans %llu running %llu\n",
 513                        (unsigned long long)trans->transid,
 514                        (unsigned long long)
 515                        root->fs_info->running_transaction->transid);
 516                 WARN_ON(1);
 517         }
 518         if (trans->transid != root->fs_info->generation) {
 519                 printk(KERN_CRIT "trans %llu running %llu\n",
 520                        (unsigned long long)trans->transid,
 521                        (unsigned long long)root->fs_info->generation);
 522                 WARN_ON(1);
 523         }
 524
 525         if (!should_cow_block(trans, root, buf)) {
 526                 *cow_ret = buf;
 527                 return 0;
 528         }
 529
 530         search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
 531
 532         if (parent)
 533                 btrfs_set_lock_blocking(parent);
 534         btrfs_set_lock_blocking(buf);
 535
 536         ret = __btrfs_cow_block(trans, root, buf, parent,
 537                                  parent_slot, cow_ret, search_start, 0);
 538         return ret;
 539 }
 540
 541 /*
 542  * helper function for defrag to decide if two blocks pointed to by a
 543  * node are actually close by
 544  */
 545 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 546 {
 547         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 548                 return 1;
 549         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 550                 return 1;
 551         return 0;
 552 }
 553
 554 /*
 555  * compare two keys in a memcmp fashion
 556  */
 557 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 558 {
 559         struct btrfs_key k1;
 560
 561         btrfs_disk_key_to_cpu(&k1, disk);
 562
 563         return btrfs_comp_cpu_keys(&k1, k2);
 564 }
 565
 566 /*
 567  * same as comp_keys only with two btrfs_key's
 568  */
 569 int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
 570 {
 571         if (k1->objectid > k2->objectid)
 572                 return 1;
 573         if (k1->objectid < k2->objectid)
 574                 return -1;
 575         if (k1->type > k2->type)
 576                 return 1;
 577         if (k1->type < k2->type)
 578                 return -1;
 579         if (k1->offset > k2->offset)
 580                 return 1;
 581         if (k1->offset < k2->offset)
 582                 return -1;
 583         return 0;
 584 }
 585
 586 /*
 587  * this is used by the defrag code to go through all the
 588  * leaves pointed to by a node and reallocate them so that
 589  * disk order is close to key order
 590  */
 591 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 592                        struct btrfs_root *root, struct extent_buffer *parent,
 593                        int start_slot, int cache_only, u64 *last_ret,
 594                        struct btrfs_key *progress)
 595 {
 596         struct extent_buffer *cur;
 597         u64 blocknr;
 598         u64 gen;
 599         u64 search_start = *last_ret;
 600         u64 last_block = 0;
 601         u64 other;
 602         u32 parent_nritems;
 603         int end_slot;
 604         int i;
 605         int err = 0;
 606         int parent_level;
 607         int uptodate;
 608         u32 blocksize;
 609         int progress_passed = 0;
 610         struct btrfs_disk_key disk_key;
 611
 612         parent_level = btrfs_header_level(parent);
 613         if (cache_only && parent_level != 1)
 614                 return 0;
 615
 616         if (trans->transaction != root->fs_info->running_transaction)
 617                 WARN_ON(1);
 618         if (trans->transid != root->fs_info->generation)
 619                 WARN_ON(1);
 620
 621         parent_nritems = btrfs_header_nritems(parent);
 622         blocksize = btrfs_level_size(root, parent_level - 1);
 623         end_slot = parent_nritems;
 624
 625         if (parent_nritems == 1)
 626                 return 0;
 627
 628         btrfs_set_lock_blocking(parent);
 629
 630         for (i = start_slot; i < end_slot; i++) {
 631                 int close = 1;
 632
 633                 if (!parent->map_token) {
 634                         map_extent_buffer(parent,
 635                                         btrfs_node_key_ptr_offset(i),
 636                                         sizeof(struct btrfs_key_ptr),
 637                                         &parent->map_token, &parent->kaddr,
 638                                         &parent->map_start, &parent->map_len,
 639                                         KM_USER1);
 640                 }
 641                 btrfs_node_key(parent, &disk_key, i);
 642                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
 643                         continue;
 644
 645                 progress_passed = 1;
 646                 blocknr = btrfs_node_blockptr(parent, i);
 647                 gen = btrfs_node_ptr_generation(parent, i);
 648                 if (last_block == 0)
 649                         last_block = blocknr;
 650
 651                 if (i > 0) {
 652                         other = btrfs_node_blockptr(parent, i - 1);
 653                         close = close_blocks(blocknr, other, blocksize);
 654                 }
 655                 if (!close && i < end_slot - 2) {
 656                         other = btrfs_node_blockptr(parent, i + 1);
 657                         close = close_blocks(blocknr, other, blocksize);
 658                 }
 659                 if (close) {
 660                         last_block = blocknr;
 661                         continue;
 662                 }
 663                 if (parent->map_token) {
 664                         unmap_extent_buffer(parent, parent->map_token,
 665                                             KM_USER1);
 666                         parent->map_token = NULL;
 667                 }
 668
 669                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
 670                 if (cur)
 671                         uptodate = btrfs_buffer_uptodate(cur, gen);
 672                 else
 673                         uptodate = 0;
 674                 if (!cur || !uptodate) {
 675                         if (cache_only) {
 676                                 free_extent_buffer(cur);
 677                                 continue;
 678                         }
 679                         if (!cur) {
 680                                 cur = read_tree_block(root, blocknr,
 681                                                          blocksize, gen);
 682                         } else if (!uptodate) {
 683                                 btrfs_read_buffer(cur, gen);
 684                         }
 685                 }
 686                 if (search_start == 0)
 687                         search_start = last_block;
 688
 689                 btrfs_tree_lock(cur);
 690                 btrfs_set_lock_blocking(cur);
 691                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 692                                         &cur, search_start,
 693                                         min(16 * blocksize,
 694                                             (end_slot - i) * blocksize));
 695                 if (err) {
 696                         btrfs_tree_unlock(cur);
 697                         free_extent_buffer(cur);
 698                         break;
 699                 }
 700                 search_start = cur->start;
 701                 last_block = cur->start;
 702                 *last_ret = search_start;
 703                 btrfs_tree_unlock(cur);
 704                 free_extent_buffer(cur);
 705         }
 706         if (parent->map_token) {
 707                 unmap_extent_buffer(parent, parent->map_token,
 708                                     KM_USER1);
 709                 parent->map_token = NULL;
 710         }
 711         return err;
 712 }
 713
 714 /*
 715  * The leaf data grows from end-to-front in the node.
 716  * this returns the address of the start of the last item,
 717  * which is the stop of the leaf data stack
 718  */
 719 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 720                                          struct extent_buffer *leaf)
 721 {
 722         u32 nr = btrfs_header_nritems(leaf);
 723         if (nr == 0)
 724                 return BTRFS_LEAF_DATA_SIZE(root);
 725         return btrfs_item_offset_nr(leaf, nr - 1);
 726 }
 727
 728 /*
 729  * extra debugging checks to make sure all the items in a key are
 730  * well formed and in the proper order
 731  */
 732 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 733                       int level)
 734 {
 735         struct extent_buffer *parent = NULL;
 736         struct extent_buffer *node = path->nodes[level];
 737         struct btrfs_disk_key parent_key;
 738         struct btrfs_disk_key node_key;
 739         int parent_slot;
 740         int slot;
 741         struct btrfs_key cpukey;
 742         u32 nritems = btrfs_header_nritems(node);
 743
 744         if (path->nodes[level + 1])
 745                 parent = path->nodes[level + 1];
 746
 747         slot = path->slots[level];
 748         BUG_ON(nritems == 0);
 749         if (parent) {
 750                 parent_slot = path->slots[level + 1];
 751                 btrfs_node_key(parent, &parent_key, parent_slot);
 752                 btrfs_node_key(node, &node_key, 0);
 753                 BUG_ON(memcmp(&parent_key, &node_key,
 754                               sizeof(struct btrfs_disk_key)));
 755                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 756                        btrfs_header_bytenr(node));
 757         }
 758         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 759         if (slot != 0) {
 760                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 761                 btrfs_node_key(node, &node_key, slot);
 762                 BUG_ON(comp_keys(&node_key, &cpukey) <= 0);
 763         }
 764         if (slot < nritems - 1) {
 765                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 766                 btrfs_node_key(node, &node_key, slot);
 767                 BUG_ON(comp_keys(&node_key, &cpukey) >= 0);
 768         }
 769         return 0;
 770 }
 771
 772 /*
 773  * extra checking to make sure all the items in a leaf are
 774  * well formed and in the proper order
 775  */
 776 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 777                       int level)
 778 {
 779         struct extent_buffer *leaf = path->nodes[level];
 780         struct extent_buffer *parent = NULL;
 781         int parent_slot;
 782         struct btrfs_key cpukey;
 783         struct btrfs_disk_key parent_key;
 784         struct btrfs_disk_key leaf_key;
 785         int slot = path->slots[0];
 786
 787         u32 nritems = btrfs_header_nritems(leaf);
 788
 789         if (path->nodes[level + 1])
 790                 parent = path->nodes[level + 1];
 791
 792         if (nritems == 0)
 793                 return 0;
 794
 795         if (parent) {
 796                 parent_slot = path->slots[level + 1];
 797                 btrfs_node_key(parent, &parent_key, parent_slot);
 798                 btrfs_item_key(leaf, &leaf_key, 0);
 799
 800                 BUG_ON(memcmp(&parent_key, &leaf_key,
 801                        sizeof(struct btrfs_disk_key)));
 802                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 803                        btrfs_header_bytenr(leaf));
 804         }
 805         if (slot != 0 && slot < nritems - 1) {
 806                 btrfs_item_key(leaf, &leaf_key, slot);
 807                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 808                 if (comp_keys(&leaf_key, &cpukey) <= 0) {
 809                         btrfs_print_leaf(root, leaf);
 810                         printk(KERN_CRIT "slot %d offset bad key\n", slot);
 811                         BUG_ON(1);
 812                 }
 813                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 814                        btrfs_item_end_nr(leaf, slot)) {
 815                         btrfs_print_leaf(root, leaf);
 816                         printk(KERN_CRIT "slot %d offset bad\n", slot);
 817                         BUG_ON(1);
 818                 }
 819         }
 820         if (slot < nritems - 1) {
 821                 btrfs_item_key(leaf, &leaf_key, slot);
 822                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 823                 BUG_ON(comp_keys(&leaf_key, &cpukey) >= 0);
 824                 if (btrfs_item_offset_nr(leaf, slot) !=
 825                         btrfs_item_end_nr(leaf, slot + 1)) {
 826                         btrfs_print_leaf(root, leaf);
 827                         printk(KERN_CRIT "slot %d offset bad\n", slot);
 828                         BUG_ON(1);
 829                 }
 830         }
 831         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 832                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 833         return 0;
 834 }
 835
 836 static noinline int check_block(struct btrfs_root *root,
 837                                 struct btrfs_path *path, int level)
 838 {
 839         return 0;
 840         if (level == 0)
 841                 return check_leaf(root, path, level);
 842         return check_node(root, path, level);
 843 }
 844
 845 /*
 846  * search for key in the extent_buffer.  The items start at offset p,
 847  * and they are item_size apart.  There are 'max' items in p.
 848  *
 849  * the slot in the array is returned via slot, and it points to
 850  * the place where you would insert key if it is not found in
 851  * the array.
 852  *
 853  * slot may point to max if the key is bigger than all of the keys
 854  */
 855 static noinline int generic_bin_search(struct extent_buffer *eb,
 856                                        unsigned long p,
 857                                        int item_size, struct btrfs_key *key,
 858                                        int max, int *slot)
 859 {
 860         int low = 0;
 861         int high = max;
 862         int mid;
 863         int ret;
 864         struct btrfs_disk_key *tmp = NULL;
 865         struct btrfs_disk_key unaligned;
 866         unsigned long offset;
 867         char *map_token = NULL;
 868         char *kaddr = NULL;
 869         unsigned long map_start = 0;
 870         unsigned long map_len = 0;
 871         int err;
 872
 873         while (low < high) {
 874                 mid = (low + high) / 2;
 875                 offset = p + mid * item_size;
 876
 877                 if (!map_token || offset < map_start ||
 878                     (offset + sizeof(struct btrfs_disk_key)) >
 879                     map_start + map_len) {
 880                         if (map_token) {
 881                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 882                                 map_token = NULL;
 883                         }
 884
 885                         err = map_private_extent_buffer(eb, offset,
 886                                                 sizeof(struct btrfs_disk_key),
 887                                                 &map_token, &kaddr,
 888                                                 &map_start, &map_len, KM_USER0);
 889
 890                         if (!err) {
 891                                 tmp = (struct btrfs_disk_key *)(kaddr + offset -
 892                                                         map_start);
 893                         } else {
 894                                 read_extent_buffer(eb, &unaligned,
 895                                                    offset, sizeof(unaligned));
 896                                 tmp = &unaligned;
 897                         }
 898
 899                 } else {
 900                         tmp = (struct btrfs_disk_key *)(kaddr + offset -
 901                                                         map_start);
 902                 }
 903                 ret = comp_keys(tmp, key);
 904
 905                 if (ret < 0)
 906                         low = mid + 1;
 907                 else if (ret > 0)
 908                         high = mid;
 909                 else {
 910                         *slot = mid;
 911                         if (map_token)
 912                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 913                         return 0;
 914                 }
 915         }
 916         *slot = low;
 917         if (map_token)
 918                 unmap_extent_buffer(eb, map_token, KM_USER0);
 919         return 1;
 920 }
 921
 922 /*
 923  * simple bin_search frontend that does the right thing for
 924  * leaves vs nodes
 925  */
 926 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 927                       int level, int *slot)
 928 {
 929         if (level == 0) {
 930                 return generic_bin_search(eb,
 931                                           offsetof(struct btrfs_leaf, items),
 932                                           sizeof(struct btrfs_item),
 933                                           key, btrfs_header_nritems(eb),
 934                                           slot);
 935         } else {
 936                 return generic_bin_search(eb,
 937                                           offsetof(struct btrfs_node, ptrs),
 938                                           sizeof(struct btrfs_key_ptr),
 939                                           key, btrfs_header_nritems(eb),
 940                                           slot);
 941         }
 942         return -1;
 943 }
 944
 945 int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 946                      int level, int *slot)
 947 {
 948         return bin_search(eb, key, level, slot);
 949 }
 950
 951 /* given a node and slot number, this reads the blocks it points to.  The
 952  * extent buffer is returned with a reference taken (but unlocked).
 953  * NULL is returned on error.
 954  */
 955 static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
 956                                    struct extent_buffer *parent, int slot)
 957 {
 958         int level = btrfs_header_level(parent);
 959         if (slot < 0)
 960                 return NULL;
 961         if (slot >= btrfs_header_nritems(parent))
 962                 return NULL;
 963
 964         BUG_ON(level == 0);
 965
 966         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 967                        btrfs_level_size(root, level - 1),
 968                        btrfs_node_ptr_generation(parent, slot));
 969 }
 970
 971 /*
 972  * node level balancing, used to make sure nodes are in proper order for
 973  * item deletion.  We balance from the top down, so we have to make sure
 974  * that a deletion won't leave an node completely empty later on.
 975  */
 976 static noinline int balance_level(struct btrfs_trans_handle *trans,
 977                          struct btrfs_root *root,
 978                          struct btrfs_path *path, int level)
 979 {
 980         struct extent_buffer *right = NULL;
 981         struct extent_buffer *mid;
 982         struct extent_buffer *left = NULL;
 983         struct extent_buffer *parent = NULL;
 984         int ret = 0;
 985         int wret;
 986         int pslot;
 987         int orig_slot = path->slots[level];
 988         int err_on_enospc = 0;
 989         u64 orig_ptr;
 990
 991         if (level == 0)
 992                 return 0;
 993
 994         mid = path->nodes[level];
 995
 996         WARN_ON(!path->locks[level]);
 997         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 998
 999         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1000
1001         if (level < BTRFS_MAX_LEVEL - 1)
1002                 parent = path->nodes[level + 1];
1003         pslot = path->slots[level + 1];
1004
1005         /*
1006          * deal with the case where there is only one pointer in the root
1007          * by promoting the node below to a root
1008          */
1009         if (!parent) {
1010                 struct extent_buffer *child;
1011
1012                 if (btrfs_header_nritems(mid) != 1)
1013                         return 0;
1014
1015                 /* promote the child to a root */
1016                 child = read_node_slot(root, mid, 0);
1017                 BUG_ON(!child);
1018                 btrfs_tree_lock(child);
1019                 btrfs_set_lock_blocking(child);
1020                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1021                 BUG_ON(ret);
1022
1023                 spin_lock(&root->node_lock);
1024                 root->node = child;
1025                 spin_unlock(&root->node_lock);
1026
1027                 add_root_to_dirty_list(root);
1028                 btrfs_tree_unlock(child);
1029
1030                 path->locks[level] = 0;
1031                 path->nodes[level] = NULL;
1032                 clean_tree_block(trans, root, mid);
1033                 btrfs_tree_unlock(mid);
1034                 /* once for the path */
1035                 free_extent_buffer(mid);
1036                 ret = btrfs_free_tree_block(trans, root, mid->start, mid->len,
1037                                             0, root->root_key.objectid, level);
1038                 /* once for the root ptr */
1039                 free_extent_buffer(mid);
1040                 return ret;
1041         }
1042         if (btrfs_header_nritems(mid) >
1043             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
1044                 return 0;
1045
1046         if (btrfs_header_nritems(mid) < 2)
1047                 err_on_enospc = 1;
1048
1049         left = read_node_slot(root, parent, pslot - 1);
1050         if (left) {
1051                 btrfs_tree_lock(left);
1052                 btrfs_set_lock_blocking(left);
1053                 wret = btrfs_cow_block(trans, root, left,
1054                                        parent, pslot - 1, &left);
1055                 if (wret) {
1056                         ret = wret;
1057                         goto enospc;
1058                 }
1059         }
1060         right = read_node_slot(root, parent, pslot + 1);
1061         if (right) {
1062                 btrfs_tree_lock(right);
1063                 btrfs_set_lock_blocking(right);
1064                 wret = btrfs_cow_block(trans, root, right,
1065                                        parent, pslot + 1, &right);
1066                 if (wret) {
1067                         ret = wret;
1068                         goto enospc;
1069                 }
1070         }
1071
1072         /* first, try to make some room in the middle buffer */
1073         if (left) {
1074                 orig_slot += btrfs_header_nritems(left);
1075                 wret = push_node_left(trans, root, left, mid, 1);
1076                 if (wret < 0)
1077                         ret = wret;
1078                 if (btrfs_header_nritems(mid) < 2)
1079                         err_on_enospc = 1;
1080         }
1081
1082         /*
1083          * then try to empty the right most buffer into the middle
1084          */
1085         if (right) {
1086                 wret = push_node_left(trans, root, mid, right, 1);
1087                 if (wret < 0 && wret != -ENOSPC)
1088                         ret = wret;
1089                 if (btrfs_header_nritems(right) == 0) {
1090                         u64 bytenr = right->start;
1091                         u32 blocksize = right->len;
1092
1093                         clean_tree_block(trans, root, right);
1094                         btrfs_tree_unlock(right);
1095                         free_extent_buffer(right);
1096                         right = NULL;
1097                         wret = del_ptr(trans, root, path, level + 1, pslot +
1098                                        1);
1099                         if (wret)
1100                                 ret = wret;
1101                         wret = btrfs_free_tree_block(trans, root,
1102                                                      bytenr, blocksize, 0,
1103                                                      root->root_key.objectid,
1104                                                      level);
1105                         if (wret)
1106                                 ret = wret;
1107                 } else {
1108                         struct btrfs_disk_key right_key;
1109                         btrfs_node_key(right, &right_key, 0);
1110                         btrfs_set_node_key(parent, &right_key, pslot + 1);
1111                         btrfs_mark_buffer_dirty(parent);
1112                 }
1113         }
1114         if (btrfs_header_nritems(mid) == 1) {
1115                 /*
1116                  * we're not allowed to leave a node with one item in the
1117                  * tree during a delete.  A deletion from lower in the tree
1118                  * could try to delete the only pointer in this node.
1119                  * So, pull some keys from the left.
1120                  * There has to be a left pointer at this point because
1121                  * otherwise we would have pulled some pointers from the
1122                  * right
1123                  */
1124                 BUG_ON(!left);
1125                 wret = balance_node_right(trans, root, mid, left);
1126                 if (wret < 0) {
1127                         ret = wret;
1128                         goto enospc;
1129                 }
1130                 if (wret == 1) {
1131                         wret = push_node_left(trans, root, left, mid, 1);
1132                         if (wret < 0)
1133                                 ret = wret;
1134                 }
1135                 BUG_ON(wret == 1);
1136         }
1137         if (btrfs_header_nritems(mid) == 0) {
1138                 /* we've managed to empty the middle node, drop it */
1139                 u64 bytenr = mid->start;
1140                 u32 blocksize = mid->len;
1141
1142                 clean_tree_block(trans, root, mid);
1143                 btrfs_tree_unlock(mid);
1144                 free_extent_buffer(mid);
1145                 mid = NULL;
1146                 wret = del_ptr(trans, root, path, level + 1, pslot);
1147                 if (wret)
1148                         ret = wret;
1149                 wret = btrfs_free_tree_block(trans, root, bytenr, blocksize,
1150                                          0, root->root_key.objectid, level);
1151                 if (wret)
1152                         ret = wret;
1153         } else {
1154                 /* update the parent key to reflect our changes */
1155                 struct btrfs_disk_key mid_key;
1156                 btrfs_node_key(mid, &mid_key, 0);
1157                 btrfs_set_node_key(parent, &mid_key, pslot);
1158                 btrfs_mark_buffer_dirty(parent);
1159         }
1160
1161         /* update the path */
1162         if (left) {
1163                 if (btrfs_header_nritems(left) > orig_slot) {
1164                         extent_buffer_get(left);
1165                         /* left was locked after cow */
1166                         path->nodes[level] = left;
1167                         path->slots[level + 1] -= 1;
1168                         path->slots[level] = orig_slot;
1169                         if (mid) {
1170                                 btrfs_tree_unlock(mid);
1171                                 free_extent_buffer(mid);
1172                         }
1173                 } else {
1174                         orig_slot -= btrfs_header_nritems(left);
1175                         path->slots[level] = orig_slot;
1176                 }
1177         }
1178         /* double check we haven't messed things up */
1179         check_block(root, path, level);
1180         if (orig_ptr !=
1181             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1182                 BUG();
1183 enospc:
1184         if (right) {
1185                 btrfs_tree_unlock(right);
1186                 free_extent_buffer(right);
1187         }
1188         if (left) {
1189                 if (path->nodes[level] != left)
1190                         btrfs_tree_unlock(left);
1191                 free_extent_buffer(left);
1192         }
1193         return ret;
1194 }
1195
1196 /* Node balancing for insertion.  Here we only split or push nodes around
1197  * when they are completely full.  This is also done top down, so we
1198  * have to be pessimistic.
1199  */
1200 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1201                                           struct btrfs_root *root,
1202                                           struct btrfs_path *path, int level)
1203 {
1204         struct extent_buffer *right = NULL;
1205         struct extent_buffer *mid;
1206         struct extent_buffer *left = NULL;
1207         struct extent_buffer *parent = NULL;
1208         int ret = 0;
1209         int wret;
1210         int pslot;
1211         int orig_slot = path->slots[level];
1212         u64 orig_ptr;
1213
1214         if (level == 0)
1215                 return 1;
1216
1217         mid = path->nodes[level];
1218         WARN_ON(btrfs_header_generation(mid) != trans->transid);
1219         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1220
1221         if (level < BTRFS_MAX_LEVEL - 1)
1222                 parent = path->nodes[level + 1];
1223         pslot = path->slots[level + 1];
1224
1225         if (!parent)
1226                 return 1;
1227
1228         left = read_node_slot(root, parent, pslot - 1);
1229
1230         /* first, try to make some room in the middle buffer */
1231         if (left) {
1232                 u32 left_nr;
1233
1234                 btrfs_tree_lock(left);
1235                 btrfs_set_lock_blocking(left);
1236
1237                 left_nr = btrfs_header_nritems(left);
1238                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1239                         wret = 1;
1240                 } else {
1241                         ret = btrfs_cow_block(trans, root, left, parent,
1242                                               pslot - 1, &left);
1243                         if (ret)
1244                                 wret = 1;
1245                         else {
1246                                 wret = push_node_left(trans, root,
1247                                                       left, mid, 0);
1248                         }
1249                 }
1250                 if (wret < 0)
1251                         ret = wret;
1252                 if (wret == 0) {
1253                         struct btrfs_disk_key disk_key;
1254                         orig_slot += left_nr;
1255                         btrfs_node_key(mid, &disk_key, 0);
1256                         btrfs_set_node_key(parent, &disk_key, pslot);
1257                         btrfs_mark_buffer_dirty(parent);
1258                         if (btrfs_header_nritems(left) > orig_slot) {
1259                                 path->nodes[level] = left;
1260                                 path->slots[level + 1] -= 1;
1261                                 path->slots[level] = orig_slot;
1262                                 btrfs_tree_unlock(mid);
1263                                 free_extent_buffer(mid);
1264                         } else {
1265                                 orig_slot -=
1266                                         btrfs_header_nritems(left);
1267                                 path->slots[level] = orig_slot;
1268                                 btrfs_tree_unlock(left);
1269                                 free_extent_buffer(left);
1270                         }
1271                         return 0;
1272                 }
1273                 btrfs_tree_unlock(left);
1274                 free_extent_buffer(left);
1275         }
1276         right = read_node_slot(root, parent, pslot + 1);
1277
1278         /*
1279          * then try to empty the right most buffer into the middle
1280          */
1281         if (right) {
1282                 u32 right_nr;
1283
1284                 btrfs_tree_lock(right);
1285                 btrfs_set_lock_blocking(right);
1286
1287                 right_nr = btrfs_header_nritems(right);
1288                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1289                         wret = 1;
1290                 } else {
1291                         ret = btrfs_cow_block(trans, root, right,
1292                                               parent, pslot + 1,
1293                                               &right);
1294                         if (ret)
1295                                 wret = 1;
1296                         else {
1297                                 wret = balance_node_right(trans, root,
1298                                                           right, mid);
1299                         }
1300                 }
1301                 if (wret < 0)
1302                         ret = wret;
1303                 if (wret == 0) {
1304                         struct btrfs_disk_key disk_key;
1305
1306                         btrfs_node_key(right, &disk_key, 0);
1307                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
1308                         btrfs_mark_buffer_dirty(parent);
1309
1310                         if (btrfs_header_nritems(mid) <= orig_slot) {
1311                                 path->nodes[level] = right;
1312                                 path->slots[level + 1] += 1;
1313                                 path->slots[level] = orig_slot -
1314                                         btrfs_header_nritems(mid);
1315                                 btrfs_tree_unlock(mid);
1316                                 free_extent_buffer(mid);
1317                         } else {
1318                                 btrfs_tree_unlock(right);
1319                                 free_extent_buffer(right);
1320                         }
1321                         return 0;
1322                 }
1323                 btrfs_tree_unlock(right);
1324                 free_extent_buffer(right);
1325         }
1326         return 1;
1327 }
1328
1329 /*
1330  * readahead one full node of leaves, finding things that are close
1331  * to the block in 'slot', and triggering ra on them.
1332  */
1333 static void reada_for_search(struct btrfs_root *root,
1334                              struct btrfs_path *path,
1335                              int level, int slot, u64 objectid)
1336 {
1337         struct extent_buffer *node;
1338         struct btrfs_disk_key disk_key;
1339         u32 nritems;
1340         u64 search;
1341         u64 target;
1342         u64 nread = 0;
1343         int direction = path->reada;
1344         struct extent_buffer *eb;
1345         u32 nr;
1346         u32 blocksize;
1347         u32 nscan = 0;
1348
1349         if (level != 1)
1350                 return;
1351
1352         if (!path->nodes[level])
1353                 return;
1354
1355         node = path->nodes[level];
1356
1357         search = btrfs_node_blockptr(node, slot);
1358         blocksize = btrfs_level_size(root, level - 1);
1359         eb = btrfs_find_tree_block(root, search, blocksize);
1360         if (eb) {
1361                 free_extent_buffer(eb);
1362                 return;
1363         }
1364
1365         target = search;
1366
1367         nritems = btrfs_header_nritems(node);
1368         nr = slot;
1369         while (1) {
1370                 if (direction < 0) {
1371                         if (nr == 0)
1372                                 break;
1373                         nr--;
1374                 } else if (direction > 0) {
1375                         nr++;
1376                         if (nr >= nritems)
1377                                 break;
1378                 }
1379                 if (path->reada < 0 && objectid) {
1380                         btrfs_node_key(node, &disk_key, nr);
1381                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1382                                 break;
1383                 }
1384                 search = btrfs_node_blockptr(node, nr);
1385                 if ((search <= target && target - search <= 65536) ||
1386                     (search > target && search - target <= 65536)) {
1387                         readahead_tree_block(root, search, blocksize,
1388                                      btrfs_node_ptr_generation(node, nr));
1389                         nread += blocksize;
1390                 }
1391                 nscan++;
1392                 if ((nread > 65536 || nscan > 32))
1393                         break;
1394         }
1395 }
1396
1397 /*
1398  * returns -EAGAIN if it had to drop the path, or zero if everything was in
1399  * cache
1400  */
1401 static noinline int reada_for_balance(struct btrfs_root *root,
1402                                       struct btrfs_path *path, int level)
1403 {
1404         int slot;
1405         int nritems;
1406         struct extent_buffer *parent;
1407         struct extent_buffer *eb;
1408         u64 gen;
1409         u64 block1 = 0;
1410         u64 block2 = 0;
1411         int ret = 0;
1412         int blocksize;
1413
1414         parent = path->nodes[level + 1];
1415         if (!parent)
1416                 return 0;
1417
1418         nritems = btrfs_header_nritems(parent);
1419         slot = path->slots[level + 1];
1420         blocksize = btrfs_level_size(root, level);
1421
1422         if (slot > 0) {
1423                 block1 = btrfs_node_blockptr(parent, slot - 1);
1424                 gen = btrfs_node_ptr_generation(parent, slot - 1);
1425                 eb = btrfs_find_tree_block(root, block1, blocksize);
1426                 if (eb && btrfs_buffer_uptodate(eb, gen))
1427                         block1 = 0;
1428                 free_extent_buffer(eb);
1429         }
1430         if (slot + 1 < nritems) {
1431                 block2 = btrfs_node_blockptr(parent, slot + 1);
1432                 gen = btrfs_node_ptr_generation(parent, slot + 1);
1433                 eb = btrfs_find_tree_block(root, block2, blocksize);
1434                 if (eb && btrfs_buffer_uptodate(eb, gen))
1435                         block2 = 0;
1436                 free_extent_buffer(eb);
1437         }
1438         if (block1 || block2) {
1439                 ret = -EAGAIN;
1440
1441                 /* release the whole path */
1442                 btrfs_release_path(root, path);
1443
1444                 /* read the blocks */
1445                 if (block1)
1446                         readahead_tree_block(root, block1, blocksize, 0);
1447                 if (block2)
1448                         readahead_tree_block(root, block2, blocksize, 0);
1449
1450                 if (block1) {
1451                         eb = read_tree_block(root, block1, blocksize, 0);
1452                         free_extent_buffer(eb);
1453                 }
1454                 if (block2) {
1455                         eb = read_tree_block(root, block2, blocksize, 0);
1456                         free_extent_buffer(eb);
1457                 }
1458         }
1459         return ret;
1460 }
1461
1462
1463 /*
1464  * when we walk down the tree, it is usually safe to unlock the higher layers
1465  * in the tree.  The exceptions are when our path goes through slot 0, because
1466  * operations on the tree might require changing key pointers higher up in the
1467  * tree.
1468  *
1469  * callers might also have set path->keep_locks, which tells this code to keep
1470  * the lock if the path points to the last slot in the block.  This is part of
1471  * walking through the tree, and selecting the next slot in the higher block.
1472  *
1473  * lowest_unlock sets the lowest level in the tree we're allowed to unlock.  so
1474  * if lowest_unlock is 1, level 0 won't be unlocked
1475  */
1476 static noinline void unlock_up(struct btrfs_path *path, int level,
1477                                int lowest_unlock)
1478 {
1479         int i;
1480         int skip_level = level;
1481         int no_skips = 0;
1482         struct extent_buffer *t;
1483
1484         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1485                 if (!path->nodes[i])
1486                         break;
1487                 if (!path->locks[i])
1488                         break;
1489                 if (!no_skips && path->slots[i] == 0) {
1490                         skip_level = i + 1;
1491                         continue;
1492                 }
1493                 if (!no_skips && path->keep_locks) {
1494                         u32 nritems;
1495                         t = path->nodes[i];
1496                         nritems = btrfs_header_nritems(t);
1497                         if (nritems < 1 || path->slots[i] >= nritems - 1) {
1498                                 skip_level = i + 1;
1499                                 continue;
1500                         }
1501                 }
1502                 if (skip_level < i && i >= lowest_unlock)
1503                         no_skips = 1;
1504
1505                 t = path->nodes[i];
1506                 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
1507                         btrfs_tree_unlock(t);
1508                         path->locks[i] = 0;
1509                 }
1510         }
1511 }
1512
1513 /*
1514  * This releases any locks held in the path starting at level and
1515  * going all the way up to the root.
1516  *
1517  * btrfs_search_slot will keep the lock held on higher nodes in a few
1518  * corner cases, such as COW of the block at slot zero in the node.  This
1519  * ignores those rules, and it should only be called when there are no
1520  * more updates to be done higher up in the tree.
1521  */
1522 noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
1523 {
1524         int i;
1525
1526         if (path->keep_locks)
1527                 return;
1528
1529         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1530                 if (!path->nodes[i])
1531                         continue;
1532                 if (!path->locks[i])
1533                         continue;
1534                 btrfs_tree_unlock(path->nodes[i]);
1535                 path->locks[i] = 0;
1536         }
1537 }
1538
1539 /*
1540  * helper function for btrfs_search_slot.  The goal is to find a block
1541  * in cache without setting the path to blocking.  If we find the block
1542  * we return zero and the path is unchanged.
1543  *
1544  * If we can't find the block, we set the path blocking and do some
1545  * reada.  -EAGAIN is returned and the search must be repeated.
1546  */
1547 static int
1548 read_block_for_search(struct btrfs_trans_handle *trans,
1549                        struct btrfs_root *root, struct btrfs_path *p,
1550                        struct extent_buffer **eb_ret, int level, int slot,
1551                        struct btrfs_key *key)
1552 {
1553         u64 blocknr;
1554         u64 gen;
1555         u32 blocksize;
1556         struct extent_buffer *b = *eb_ret;
1557         struct extent_buffer *tmp;
1558         int ret;
1559
1560         blocknr = btrfs_node_blockptr(b, slot);
1561         gen = btrfs_node_ptr_generation(b, slot);
1562         blocksize = btrfs_level_size(root, level - 1);
1563
1564         tmp = btrfs_find_tree_block(root, blocknr, blocksize);
1565         if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
1566                 /*
1567                  * we found an up to date block without sleeping, return
1568                  * right away
1569                  */
1570                 *eb_ret = tmp;
1571                 return 0;
1572         }
1573
1574         /*
1575          * reduce lock contention at high levels
1576          * of the btree by dropping locks before
1577          * we read.  Don't release the lock on the current
1578          * level because we need to walk this node to figure
1579          * out which blocks to read.
1580          */
1581         btrfs_unlock_up_safe(p, level + 1);
1582         btrfs_set_path_blocking(p);
1583
1584         if (tmp)
1585                 free_extent_buffer(tmp);
1586         if (p->reada)
1587                 reada_for_search(root, p, level, slot, key->objectid);
1588
1589         btrfs_release_path(NULL, p);
1590
1591         ret = -EAGAIN;
1592         tmp = read_tree_block(root, blocknr, blocksize, gen);
1593         if (tmp) {
1594                 /*
1595                  * If the read above didn't mark this buffer up to date,
1596                  * it will never end up being up to date.  Set ret to EIO now
1597                  * and give up so that our caller doesn't loop forever
1598                  * on our EAGAINs.
1599                  */
1600                 if (!btrfs_buffer_uptodate(tmp, 0))
1601                         ret = -EIO;
1602                 free_extent_buffer(tmp);
1603         }
1604         return ret;
1605 }
1606
1607 /*
1608  * helper function for btrfs_search_slot.  This does all of the checks
1609  * for node-level blocks and does any balancing required based on
1610  * the ins_len.
1611  *
1612  * If no extra work was required, zero is returned.  If we had to
1613  * drop the path, -EAGAIN is returned and btrfs_search_slot must
1614  * start over
1615  */
1616 static int
1617 setup_nodes_for_search(struct btrfs_trans_handle *trans,
1618                        struct btrfs_root *root, struct btrfs_path *p,
1619                        struct extent_buffer *b, int level, int ins_len)
1620 {
1621         int ret;
1622         if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1623             BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
1624                 int sret;
1625
1626                 sret = reada_for_balance(root, p, level);
1627                 if (sret)
1628                         goto again;
1629
1630                 btrfs_set_path_blocking(p);
1631                 sret = split_node(trans, root, p, level);
1632                 btrfs_clear_path_blocking(p, NULL);
1633
1634                 BUG_ON(sret > 0);
1635                 if (sret) {
1636                         ret = sret;
1637                         goto done;
1638                 }
1639                 b = p->nodes[level];
1640         } else if (ins_len < 0 && btrfs_header_nritems(b) <
1641                    BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
1642                 int sret;
1643
1644                 sret = reada_for_balance(root, p, level);
1645                 if (sret)
1646                         goto again;
1647
1648                 btrfs_set_path_blocking(p);
1649                 sret = balance_level(trans, root, p, level);
1650                 btrfs_clear_path_blocking(p, NULL);
1651
1652                 if (sret) {
1653                         ret = sret;
1654                         goto done;
1655                 }
1656                 b = p->nodes[level];
1657                 if (!b) {
1658                         btrfs_release_path(NULL, p);
1659                         goto again;
1660                 }
1661                 BUG_ON(btrfs_header_nritems(b) == 1);
1662         }
1663         return 0;
1664
1665 again:
1666         ret = -EAGAIN;
1667 done:
1668         return ret;
1669 }
1670
1671 /*
1672  * look for key in the tree.  path is filled in with nodes along the way
1673  * if key is found, we return zero and you can find the item in the leaf
1674  * level of the path (level 0)
1675  *
1676  * If the key isn't found, the path points to the slot where it should
1677  * be inserted, and 1 is returned.  If there are other errors during the
1678  * search a negative error number is returned.
1679  *
1680  * if ins_len > 0, nodes and leaves will be split as we walk down the
1681  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
1682  * possible)
1683  */
1684 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1685                       *root, struct btrfs_key *key, struct btrfs_path *p, int
1686                       ins_len, int cow)
1687 {
1688         struct extent_buffer *b;
1689         int slot;
1690         int ret;
1691         int err;
1692         int level;
1693         int lowest_unlock = 1;
1694         u8 lowest_level = 0;
1695
1696         lowest_level = p->lowest_level;
1697         WARN_ON(lowest_level && ins_len > 0);
1698         WARN_ON(p->nodes[0] != NULL);
1699
1700         if (ins_len < 0)
1701                 lowest_unlock = 2;
1702
1703 again:
1704         if (p->search_commit_root) {
1705                 b = root->commit_root;
1706                 extent_buffer_get(b);
1707                 if (!p->skip_locking)
1708                         btrfs_tree_lock(b);
1709         } else {
1710                 if (p->skip_locking)
1711                         b = btrfs_root_node(root);
1712                 else
1713                         b = btrfs_lock_root_node(root);
1714         }
1715
1716         while (b) {
1717                 level = btrfs_header_level(b);
1718
1719                 /*
1720                  * setup the path here so we can release it under lock
1721                  * contention with the cow code
1722                  */
1723                 p->nodes[level] = b;
1724                 if (!p->skip_locking)
1725                         p->locks[level] = 1;
1726
1727                 if (cow) {
1728                         /*
1729                          * if we don't really need to cow this block
1730                          * then we don't want to set the path blocking,
1731                          * so we test it here
1732                          */
1733                         if (!should_cow_block(trans, root, b))
1734                                 goto cow_done;
1735
1736                         btrfs_set_path_blocking(p);
1737
1738                         err = btrfs_cow_block(trans, root, b,
1739                                               p->nodes[level + 1],
1740                                               p->slots[level + 1], &b);
1741                         if (err) {
1742                                 free_extent_buffer(b);
1743                                 ret = err;
1744                                 goto done;
1745                         }
1746                 }
1747 cow_done:
1748                 BUG_ON(!cow && ins_len);
1749                 if (level != btrfs_header_level(b))
1750                         WARN_ON(1);
1751                 level = btrfs_header_level(b);
1752
1753                 p->nodes[level] = b;
1754                 if (!p->skip_locking)
1755                         p->locks[level] = 1;
1756
1757                 btrfs_clear_path_blocking(p, NULL);
1758
1759                 /*
1760                  * we have a lock on b and as long as we aren't changing
1761                  * the tree, there is no way to for the items in b to change.
1762                  * It is safe to drop the lock on our parent before we
1763                  * go through the expensive btree search on b.
1764                  *
1765                  * If cow is true, then we might be changing slot zero,
1766                  * which may require changing the parent.  So, we can't
1767                  * drop the lock until after we know which slot we're
1768                  * operating on.
1769                  */
1770                 if (!cow)
1771                         btrfs_unlock_up_safe(p, level + 1);
1772
1773                 ret = check_block(root, p, level);
1774                 if (ret) {
1775                         ret = -1;
1776                         goto done;
1777                 }
1778
1779                 ret = bin_search(b, key, level, &slot);
1780
1781                 if (level != 0) {
1782                         int dec = 0;
1783                         if (ret && slot > 0) {
1784                                 dec = 1;
1785                                 slot -= 1;
1786                         }
1787                         p->slots[level] = slot;
1788                         err = setup_nodes_for_search(trans, root, p, b, level,
1789                                                      ins_len);
1790                         if (err == -EAGAIN)
1791                                 goto again;
1792                         if (err) {
1793                                 ret = err;
1794                                 goto done;
1795                         }
1796                         b = p->nodes[level];
1797                         slot = p->slots[level];
1798
1799                         unlock_up(p, level, lowest_unlock);
1800
1801                         if (level == lowest_level) {
1802                                 if (dec)
1803                                         p->slots[level]++;
1804                                 goto done;
1805                         }
1806
1807                         err = read_block_for_search(trans, root, p,
1808                                                     &b, level, slot, key);
1809                         if (err == -EAGAIN)
1810                                 goto again;
1811                         if (err) {
1812                                 ret = err;
1813                                 goto done;
1814                         }
1815
1816                         if (!p->skip_locking) {
1817                                 btrfs_clear_path_blocking(p, NULL);
1818                                 err = btrfs_try_spin_lock(b);
1819
1820                                 if (!err) {
1821                                         btrfs_set_path_blocking(p);
1822                                         btrfs_tree_lock(b);
1823                                         btrfs_clear_path_blocking(p, b);
1824                                 }
1825                         }
1826                 } else {
1827                         p->slots[level] = slot;
1828                         if (ins_len > 0 &&
1829                             btrfs_leaf_free_space(root, b) < ins_len) {
1830                                 btrfs_set_path_blocking(p);
1831                                 err = split_leaf(trans, root, key,
1832                                                  p, ins_len, ret == 0);
1833                                 btrfs_clear_path_blocking(p, NULL);
1834
1835                                 BUG_ON(err > 0);
1836                                 if (err) {
1837                                         ret = err;
1838                                         goto done;
1839                                 }
1840                         }
1841                         if (!p->search_for_split)
1842                                 unlock_up(p, level, lowest_unlock);
1843                         goto done;
1844                 }
1845         }
1846         ret = 1;
1847 done:
1848         /*
1849          * we don't really know what they plan on doing with the path
1850          * from here on, so for now just mark it as blocking
1851          */
1852         if (!p->leave_spinning)
1853                 btrfs_set_path_blocking(p);
1854         if (ret < 0)
1855                 btrfs_release_path(root, p);
1856         return ret;
1857 }
1858
1859 /*
1860  * adjust the pointers going up the tree, starting at level
1861  * making sure the right key of each node is points to 'key'.
1862  * This is used after shifting pointers to the left, so it stops
1863  * fixing up pointers when a given leaf/node is not in slot 0 of the
1864  * higher levels
1865  *
1866  * If this fails to write a tree block, it returns -1, but continues
1867  * fixing up the blocks in ram so the tree is consistent.
1868  */
1869 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1870                           struct btrfs_root *root, struct btrfs_path *path,
1871                           struct btrfs_disk_key *key, int level)
1872 {
1873         int i;
1874         int ret = 0;
1875         struct extent_buffer *t;
1876
1877         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1878                 int tslot = path->slots[i];
1879                 if (!path->nodes[i])
1880                         break;
1881                 t = path->nodes[i];
1882                 btrfs_set_node_key(t, key, tslot);
1883                 btrfs_mark_buffer_dirty(path->nodes[i]);
1884                 if (tslot != 0)
1885                         break;
1886         }
1887         return ret;
1888 }
1889
1890 /*
1891  * update item key.
1892  *
1893  * This function isn't completely safe. It's the caller's responsibility
1894  * that the new key won't break the order
1895  */
1896 int btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
1897                             struct btrfs_root *root, struct btrfs_path *path,
1898                             struct btrfs_key *new_key)
1899 {
1900         struct btrfs_disk_key disk_key;
1901         struct extent_buffer *eb;
1902         int slot;
1903
1904         eb = path->nodes[0];
1905         slot = path->slots[0];
1906         if (slot > 0) {
1907                 btrfs_item_key(eb, &disk_key, slot - 1);
1908                 if (comp_keys(&disk_key, new_key) >= 0)
1909                         return -1;
1910         }
1911         if (slot < btrfs_header_nritems(eb) - 1) {
1912                 btrfs_item_key(eb, &disk_key, slot + 1);
1913                 if (comp_keys(&disk_key, new_key) <= 0)
1914                         return -1;
1915         }
1916
1917         btrfs_cpu_key_to_disk(&disk_key, new_key);
1918         btrfs_set_item_key(eb, &disk_key, slot);
1919         btrfs_mark_buffer_dirty(eb);
1920         if (slot == 0)
1921                 fixup_low_keys(trans, root, path, &disk_key, 1);
1922         return 0;
1923 }
1924
1925 /*
1926  * try to push data from one node into the next node left in the
1927  * tree.
1928  *
1929  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1930  * error, and > 0 if there was no room in the left hand block.
1931  */
1932 static int push_node_left(struct btrfs_trans_handle *trans,
1933                           struct btrfs_root *root, struct extent_buffer *dst,
1934                           struct extent_buffer *src, int empty)
1935 {
1936         int push_items = 0;
1937         int src_nritems;
1938         int dst_nritems;
1939         int ret = 0;
1940
1941         src_nritems = btrfs_header_nritems(src);
1942         dst_nritems = btrfs_header_nritems(dst);
1943         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1944         WARN_ON(btrfs_header_generation(src) != trans->transid);
1945         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1946
1947         if (!empty && src_nritems <= 8)
1948                 return 1;
1949
1950         if (push_items <= 0)
1951                 return 1;
1952
1953         if (empty) {
1954                 push_items = min(src_nritems, push_items);
1955                 if (push_items < src_nritems) {
1956                         /* leave at least 8 pointers in the node if
1957                          * we aren't going to empty it
1958                          */
1959                         if (src_nritems - push_items < 8) {
1960                                 if (push_items <= 8)
1961                                         return 1;
1962                                 push_items -= 8;
1963                         }
1964                 }
1965         } else
1966                 push_items = min(src_nritems - 8, push_items);
1967
1968         copy_extent_buffer(dst, src,
1969                            btrfs_node_key_ptr_offset(dst_nritems),
1970                            btrfs_node_key_ptr_offset(0),
1971                            push_items * sizeof(struct btrfs_key_ptr));
1972
1973         if (push_items < src_nritems) {
1974                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1975                                       btrfs_node_key_ptr_offset(push_items),
1976                                       (src_nritems - push_items) *
1977                                       sizeof(struct btrfs_key_ptr));
1978         }
1979         btrfs_set_header_nritems(src, src_nritems - push_items);
1980         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1981         btrfs_mark_buffer_dirty(src);
1982         btrfs_mark_buffer_dirty(dst);
1983
1984         return ret;
1985 }
1986
1987 /*
1988  * try to push data from one node into the next node right in the
1989  * tree.
1990  *
1991  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1992  * error, and > 0 if there was no room in the right hand block.
1993  *
1994  * this will  only push up to 1/2 the contents of the left node over
1995  */
1996 static int balance_node_right(struct btrfs_trans_handle *trans,
1997                               struct btrfs_root *root,
1998                               struct extent_buffer *dst,
1999                               struct extent_buffer *src)
2000 {
2001         int push_items = 0;
2002         int max_push;
2003         int src_nritems;
2004         int dst_nritems;
2005         int ret = 0;
2006
2007         WARN_ON(btrfs_header_generation(src) != trans->transid);
2008         WARN_ON(btrfs_header_generation(dst) != trans->transid);
2009
2010         src_nritems = btrfs_header_nritems(src);
2011         dst_nritems = btrfs_header_nritems(dst);
2012         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
2013         if (push_items <= 0)
2014                 return 1;
2015
2016         if (src_nritems < 4)
2017                 return 1;
2018
2019         max_push = src_nritems / 2 + 1;
2020         /* don't try to empty the node */
2021         if (max_push >= src_nritems)
2022                 return 1;
2023
2024         if (max_push < push_items)
2025                 push_items = max_push;
2026
2027         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
2028                                       btrfs_node_key_ptr_offset(0),
2029                                       (dst_nritems) *
2030                                       sizeof(struct btrfs_key_ptr));
2031
2032         copy_extent_buffer(dst, src,
2033                            btrfs_node_key_ptr_offset(0),
2034                            btrfs_node_key_ptr_offset(src_nritems - push_items),
2035                            push_items * sizeof(struct btrfs_key_ptr));
2036
2037         btrfs_set_header_nritems(src, src_nritems - push_items);
2038         btrfs_set_header_nritems(dst, dst_nritems + push_items);
2039
2040         btrfs_mark_buffer_dirty(src);
2041         btrfs_mark_buffer_dirty(dst);
2042
2043         return ret;
2044 }
2045
2046 /*
2047  * helper function to insert a new root level in the tree.
2048  * A new node is allocated, and a single item is inserted to
2049  * point to the existing root
2050  *
2051  * returns zero on success or < 0 on failure.
2052  */
2053 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2054                            struct btrfs_root *root,
2055                            struct btrfs_path *path, int level)
2056 {
2057         u64 lower_gen;
2058         struct extent_buffer *lower;
2059         struct extent_buffer *c;
2060         struct extent_buffer *old;
2061         struct btrfs_disk_key lower_key;
2062
2063         BUG_ON(path->nodes[level]);
2064         BUG_ON(path->nodes[level-1] != root->node);
2065
2066         lower = path->nodes[level-1];
2067         if (level == 1)
2068                 btrfs_item_key(lower, &lower_key, 0);
2069         else
2070                 btrfs_node_key(lower, &lower_key, 0);
2071
2072         c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
2073                                    root->root_key.objectid, &lower_key,
2074                                    level, root->node->start, 0);
2075         if (IS_ERR(c))
2076                 return PTR_ERR(c);
2077
2078         memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
2079         btrfs_set_header_nritems(c, 1);
2080         btrfs_set_header_level(c, level);
2081         btrfs_set_header_bytenr(c, c->start);
2082         btrfs_set_header_generation(c, trans->transid);
2083         btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
2084         btrfs_set_header_owner(c, root->root_key.objectid);
2085
2086         write_extent_buffer(c, root->fs_info->fsid,
2087                             (unsigned long)btrfs_header_fsid(c),
2088                             BTRFS_FSID_SIZE);
2089
2090         write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
2091                             (unsigned long)btrfs_header_chunk_tree_uuid(c),
2092                             BTRFS_UUID_SIZE);
2093
2094         btrfs_set_node_key(c, &lower_key, 0);
2095         btrfs_set_node_blockptr(c, 0, lower->start);
2096         lower_gen = btrfs_header_generation(lower);
2097         WARN_ON(lower_gen != trans->transid);
2098
2099         btrfs_set_node_ptr_generation(c, 0, lower_gen);
2100
2101         btrfs_mark_buffer_dirty(c);
2102
2103         spin_lock(&root->node_lock);
2104         old = root->node;
2105         root->node = c;
2106         spin_unlock(&root->node_lock);
2107
2108         /* the super has an extra ref to root->node */
2109         free_extent_buffer(old);
2110
2111         add_root_to_dirty_list(root);
2112         extent_buffer_get(c);
2113         path->nodes[level] = c;
2114         path->locks[level] = 1;
2115         path->slots[level] = 0;
2116         return 0;
2117 }
2118
2119 /*
2120  * worker function to insert a single pointer in a node.
2121  * the node should have enough room for the pointer already
2122  *
2123  * slot and level indicate where you want the key to go, and
2124  * blocknr is the block the key points to.
2125  *
2126  * returns zero on success and < 0 on any error
2127  */
2128 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
2129                       *root, struct btrfs_path *path, struct btrfs_disk_key
2130                       *key, u64 bytenr, int slot, int level)
2131 {
2132         struct extent_buffer *lower;
2133         int nritems;
2134
2135         BUG_ON(!path->nodes[level]);
2136         lower = path->nodes[level];
2137         nritems = btrfs_header_nritems(lower);
2138         BUG_ON(slot > nritems);
2139         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
2140                 BUG();
2141         if (slot != nritems) {
2142                 memmove_extent_buffer(lower,
2143                               btrfs_node_key_ptr_offset(slot + 1),
2144                               btrfs_node_key_ptr_offset(slot),
2145                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
2146         }
2147         btrfs_set_node_key(lower, key, slot);
2148         btrfs_set_node_blockptr(lower, slot, bytenr);
2149         WARN_ON(trans->transid == 0);
2150         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
2151         btrfs_set_header_nritems(lower, nritems + 1);
2152         btrfs_mark_buffer_dirty(lower);
2153         return 0;
2154 }
2155
2156 /*
2157  * split the node at the specified level in path in two.
2158  * The path is corrected to point to the appropriate node after the split
2159  *
2160  * Before splitting this tries to make some room in the node by pushing
2161  * left and right, if either one works, it returns right away.
2162  *
2163  * returns 0 on success and < 0 on failure
2164  */
2165 static noinline int split_node(struct btrfs_trans_handle *trans,
2166                                struct btrfs_root *root,
2167                                struct btrfs_path *path, int level)
2168 {
2169         struct extent_buffer *c;
2170         struct extent_buffer *split;
2171         struct btrfs_disk_key disk_key;
2172         int mid;
2173         int ret;
2174         int wret;
2175         u32 c_nritems;
2176
2177         c = path->nodes[level];
2178         WARN_ON(btrfs_header_generation(c) != trans->transid);
2179         if (c == root->node) {
2180                 /* trying to split the root, lets make a new one */
2181                 ret = insert_new_root(trans, root, path, level + 1);
2182                 if (ret)
2183                         return ret;
2184         } else {
2185                 ret = push_nodes_for_insert(trans, root, path, level);
2186                 c = path->nodes[level];
2187                 if (!ret && btrfs_header_nritems(c) <
2188                     BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
2189                         return 0;
2190                 if (ret < 0)
2191                         return ret;
2192         }
2193
2194         c_nritems = btrfs_header_nritems(c);
2195         mid = (c_nritems + 1) / 2;
2196         btrfs_node_key(c, &disk_key, mid);
2197
2198         split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
2199                                         root->root_key.objectid,
2200                                         &disk_key, level, c->start, 0);
2201         if (IS_ERR(split))
2202                 return PTR_ERR(split);
2203
2204         memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
2205         btrfs_set_header_level(split, btrfs_header_level(c));
2206         btrfs_set_header_bytenr(split, split->start);
2207         btrfs_set_header_generation(split, trans->transid);
2208         btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
2209         btrfs_set_header_owner(split, root->root_key.objectid);
2210         write_extent_buffer(split, root->fs_info->fsid,
2211                             (unsigned long)btrfs_header_fsid(split),
2212                             BTRFS_FSID_SIZE);
2213         write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
2214                             (unsigned long)btrfs_header_chunk_tree_uuid(split),
2215                             BTRFS_UUID_SIZE);
2216
2217
2218         copy_extent_buffer(split, c,
2219                            btrfs_node_key_ptr_offset(0),
2220                            btrfs_node_key_ptr_offset(mid),
2221                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
2222         btrfs_set_header_nritems(split, c_nritems - mid);
2223         btrfs_set_header_nritems(c, mid);
2224         ret = 0;
2225
2226         btrfs_mark_buffer_dirty(c);
2227         btrfs_mark_buffer_dirty(split);
2228
2229         wret = insert_ptr(trans, root, path, &disk_key, split->start,
2230                           path->slots[level + 1] + 1,
2231                           level + 1);
2232         if (wret)
2233                 ret = wret;
2234
2235         if (path->slots[level] >= mid) {
2236                 path->slots[level] -= mid;
2237                 btrfs_tree_unlock(c);
2238                 free_extent_buffer(c);
2239                 path->nodes[level] = split;
2240                 path->slots[level + 1] += 1;
2241         } else {
2242                 btrfs_tree_unlock(split);
2243                 free_extent_buffer(split);
2244         }
2245         return ret;
2246 }
2247
2248 /*
2249  * how many bytes are required to store the items in a leaf.  start
2250  * and nr indicate which items in the leaf to check.  This totals up the
2251  * space used both by the item structs and the item data
2252  */
2253 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
2254 {
2255         int data_len;
2256         int nritems = btrfs_header_nritems(l);
2257         int end = min(nritems, start + nr) - 1;
2258
2259         if (!nr)
2260                 return 0;
2261         data_len = btrfs_item_end_nr(l, start);
2262         data_len = data_len - btrfs_item_offset_nr(l, end);
2263         data_len += sizeof(struct btrfs_item) * nr;
2264         WARN_ON(data_len < 0);
2265         return data_len;
2266 }
2267
2268 /*
2269  * The space between the end of the leaf items and
2270  * the start of the leaf data.  IOW, how much room
2271  * the leaf has left for both items and data
2272  */
2273 noinline int btrfs_leaf_free_space(struct btrfs_root *root,
2274                                    struct extent_buffer *leaf)
2275 {
2276         int nritems = btrfs_header_nritems(leaf);
2277         int ret;
2278         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
2279         if (ret < 0) {
2280                 printk(KERN_CRIT "leaf free space ret %d, leaf data size %lu, "
2281                        "used %d nritems %d\n",
2282                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
2283                        leaf_space_used(leaf, 0, nritems), nritems);
2284         }
2285         return ret;
2286 }
2287
2288 static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
2289                                       struct btrfs_root *root,
2290                                       struct btrfs_path *path,
2291                                       int data_size, int empty,
2292                                       struct extent_buffer *right,
2293                                       int free_space, u32 left_nritems)
2294 {
2295         struct extent_buffer *left = path->nodes[0];
2296         struct extent_buffer *upper = path->nodes[1];
2297         struct btrfs_disk_key disk_key;
2298         int slot;
2299         u32 i;
2300         int push_space = 0;
2301         int push_items = 0;
2302         struct btrfs_item *item;
2303         u32 nr;
2304         u32 right_nritems;
2305         u32 data_end;
2306         u32 this_item_size;
2307
2308         if (empty)
2309                 nr = 0;
2310         else
2311                 nr = 1;
2312
2313         if (path->slots[0] >= left_nritems)
2314                 push_space += data_size;
2315
2316         slot = path->slots[1];
2317         i = left_nritems - 1;
2318         while (i >= nr) {
2319                 item = btrfs_item_nr(left, i);
2320
2321                 if (!empty && push_items > 0) {
2322                         if (path->slots[0] > i)
2323                                 break;
2324                         if (path->slots[0] == i) {
2325                                 int space = btrfs_leaf_free_space(root, left);
2326                                 if (space + push_space * 2 > free_space)
2327                                         break;
2328                         }
2329                 }
2330
2331                 if (path->slots[0] == i)
2332                         push_space += data_size;
2333
2334                 if (!left->map_token) {
2335                         map_extent_buffer(left, (unsigned long)item,
2336                                         sizeof(struct btrfs_item),
2337                                         &left->map_token, &left->kaddr,
2338                                         &left->map_start, &left->map_len,
2339                                         KM_USER1);
2340                 }
2341
2342                 this_item_size = btrfs_item_size(left, item);
2343                 if (this_item_size + sizeof(*item) + push_space > free_space)
2344                         break;
2345
2346                 push_items++;
2347                 push_space += this_item_size + sizeof(*item);
2348                 if (i == 0)
2349                         break;
2350                 i--;
2351         }
2352         if (left->map_token) {
2353                 unmap_extent_buffer(left, left->map_token, KM_USER1);
2354                 left->map_token = NULL;
2355         }
2356
2357         if (push_items == 0)
2358                 goto out_unlock;
2359
2360         if (!empty && push_items == left_nritems)
2361                 WARN_ON(1);
2362
2363         /* push left to right */
2364         right_nritems = btrfs_header_nritems(right);
2365
2366         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
2367         push_space -= leaf_data_end(root, left);
2368
2369         /* make room in the right data area */
2370         data_end = leaf_data_end(root, right);
2371         memmove_extent_buffer(right,
2372                               btrfs_leaf_data(right) + data_end - push_space,
2373                               btrfs_leaf_data(right) + data_end,
2374                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
2375
2376         /* copy from the left data area */
2377         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
2378                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
2379                      btrfs_leaf_data(left) + leaf_data_end(root, left),
2380                      push_space);
2381
2382         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
2383                               btrfs_item_nr_offset(0),
2384                               right_nritems * sizeof(struct btrfs_item));
2385
2386         /* copy the items from left to right */
2387         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
2388                    btrfs_item_nr_offset(left_nritems - push_items),
2389                    push_items * sizeof(struct btrfs_item));
2390
2391         /* update the item pointers */
2392         right_nritems += push_items;
2393         btrfs_set_header_nritems(right, right_nritems);
2394         push_space = BTRFS_LEAF_DATA_SIZE(root);
2395         for (i = 0; i < right_nritems; i++) {
2396                 item = btrfs_item_nr(right, i);
2397                 if (!right->map_token) {
2398                         map_extent_buffer(right, (unsigned long)item,
2399                                         sizeof(struct btrfs_item),
2400                                         &right->map_token, &right->kaddr,
2401                                         &right->map_start, &right->map_len,
2402                                         KM_USER1);
2403                 }
2404                 push_space -= btrfs_item_size(right, item);
2405                 btrfs_set_item_offset(right, item, push_space);
2406         }
2407
2408         if (right->map_token) {
2409                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2410                 right->map_token = NULL;
2411         }
2412         left_nritems -= push_items;
2413         btrfs_set_header_nritems(left, left_nritems);
2414
2415         if (left_nritems)
2416                 btrfs_mark_buffer_dirty(left);
2417         btrfs_mark_buffer_dirty(right);
2418
2419         btrfs_item_key(right, &disk_key, 0);
2420         btrfs_set_node_key(upper, &disk_key, slot + 1);
2421         btrfs_mark_buffer_dirty(upper);
2422
2423         /* then fixup the leaf pointer in the path */
2424         if (path->slots[0] >= left_nritems) {
2425                 path->slots[0] -= left_nritems;
2426                 if (btrfs_header_nritems(path->nodes[0]) == 0)
2427                         clean_tree_block(trans, root, path->nodes[0]);
2428                 btrfs_tree_unlock(path->nodes[0]);
2429                 free_extent_buffer(path->nodes[0]);
2430                 path->nodes[0] = right;
2431                 path->slots[1] += 1;
2432         } else {
2433                 btrfs_tree_unlock(right);
2434                 free_extent_buffer(right);
2435         }
2436         return 0;
2437
2438 out_unlock:
2439         btrfs_tree_unlock(right);
2440         free_extent_buffer(right);
2441         return 1;
2442 }
2443
2444 /*
2445  * push some data in the path leaf to the right, trying to free up at
2446  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
2447  *
2448  * returns 1 if the push failed because the other node didn't have enough
2449  * room, 0 if everything worked out and < 0 if there were major errors.
2450  */
2451 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
2452                            *root, struct btrfs_path *path, int data_size,
2453                            int empty)
2454 {
2455         struct extent_buffer *left = path->nodes[0];
2456         struct extent_buffer *right;
2457         struct extent_buffer *upper;
2458         int slot;
2459         int free_space;
2460         u32 left_nritems;
2461         int ret;
2462
2463         if (!path->nodes[1])
2464                 return 1;
2465
2466         slot = path->slots[1];
2467         upper = path->nodes[1];
2468         if (slot >= btrfs_header_nritems(upper) - 1)
2469                 return 1;
2470
2471         btrfs_assert_tree_locked(path->nodes[1]);
2472
2473         right = read_node_slot(root, upper, slot + 1);
2474         btrfs_tree_lock(right);
2475         btrfs_set_lock_blocking(right);
2476
2477         free_space = btrfs_leaf_free_space(root, right);
2478         if (free_space < data_size)
2479                 goto out_unlock;
2480
2481         /* cow and double check */
2482         ret = btrfs_cow_block(trans, root, right, upper,
2483                               slot + 1, &right);
2484         if (ret)
2485                 goto out_unlock;
2486
2487         free_space = btrfs_leaf_free_space(root, right);
2488         if (free_space < data_size)
2489                 goto out_unlock;
2490
2491         left_nritems = btrfs_header_nritems(left);
2492         if (left_nritems == 0)
2493                 goto out_unlock;
2494
2495         return __push_leaf_right(trans, root, path, data_size, empty,
2496                                 right, free_space, left_nritems);
2497 out_unlock:
2498         btrfs_tree_unlock(right);
2499         free_extent_buffer(right);
2500         return 1;
2501 }
2502
2503 /*
2504  * push some data in the path leaf to the left, trying to free up at
2505  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
2506  */
2507 static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
2508                                      struct btrfs_root *root,
2509                                      struct btrfs_path *path, int data_size,
2510                                      int empty, struct extent_buffer *left,
2511                                      int free_space, int right_nritems)
2512 {
2513         struct btrfs_disk_key disk_key;
2514         struct extent_buffer *right = path->nodes[0];
2515         int slot;
2516         int i;
2517         int push_space = 0;
2518         int push_items = 0;
2519         struct btrfs_item *item;
2520         u32 old_left_nritems;
2521         u32 nr;
2522         int ret = 0;
2523         int wret;
2524         u32 this_item_size;
2525         u32 old_left_item_size;
2526
2527         slot = path->slots[1];
2528
2529         if (empty)
2530                 nr = right_nritems;
2531         else
2532                 nr = right_nritems - 1;
2533
2534         for (i = 0; i < nr; i++) {
2535                 item = btrfs_item_nr(right, i);
2536                 if (!right->map_token) {
2537                         map_extent_buffer(right, (unsigned long)item,
2538                                         sizeof(struct btrfs_item),
2539                                         &right->map_token, &right->kaddr,
2540                                         &right->map_start, &right->map_len,
2541                                         KM_USER1);
2542                 }
2543
2544                 if (!empty && push_items > 0) {
2545                         if (path->slots[0] < i)
2546                                 break;
2547                         if (path->slots[0] == i) {
2548                                 int space = btrfs_leaf_free_space(root, right);
2549                                 if (space + push_space * 2 > free_space)
2550                                         break;
2551                         }
2552                 }
2553
2554                 if (path->slots[0] == i)
2555                         push_space += data_size;
2556
2557                 this_item_size = btrfs_item_size(right, item);
2558                 if (this_item_size + sizeof(*item) + push_space > free_space)
2559                         break;
2560
2561                 push_items++;
2562                 push_space += this_item_size + sizeof(*item);
2563         }
2564
2565         if (right->map_token) {
2566                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2567                 right->map_token = NULL;
2568         }
2569
2570         if (push_items == 0) {
2571                 ret = 1;
2572                 goto out;
2573         }
2574         if (!empty && push_items == btrfs_header_nritems(right))
2575                 WARN_ON(1);
2576
2577         /* push data from right to left */
2578         copy_extent_buffer(left, right,
2579                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
2580                            btrfs_item_nr_offset(0),
2581                            push_items * sizeof(struct btrfs_item));
2582
2583         push_space = BTRFS_LEAF_DATA_SIZE(root) -
2584                      btrfs_item_offset_nr(right, push_items - 1);
2585
2586         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
2587                      leaf_data_end(root, left) - push_space,
2588                      btrfs_leaf_data(right) +
2589                      btrfs_item_offset_nr(right, push_items - 1),
2590                      push_space);
2591         old_left_nritems = btrfs_header_nritems(left);
2592         BUG_ON(old_left_nritems <= 0);
2593
2594         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
2595         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
2596                 u32 ioff;
2597
2598                 item = btrfs_item_nr(left, i);
2599                 if (!left->map_token) {
2600                         map_extent_buffer(left, (unsigned long)item,
2601                                         sizeof(struct btrfs_item),
2602                                         &left->map_token, &left->kaddr,
2603                                         &left->map_start, &left->map_len,
2604                                         KM_USER1);
2605                 }
2606
2607                 ioff = btrfs_item_offset(left, item);
2608                 btrfs_set_item_offset(left, item,
2609                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
2610         }
2611         btrfs_set_header_nritems(left, old_left_nritems + push_items);
2612         if (left->map_token) {
2613                 unmap_extent_buffer(left, left->map_token, KM_USER1);
2614                 left->map_token = NULL;
2615         }
2616
2617         /* fixup right node */
2618         if (push_items > right_nritems) {
2619                 printk(KERN_CRIT "push items %d nr %u\n", push_items,
2620                        right_nritems);
2621                 WARN_ON(1);
2622         }
2623
2624         if (push_items < right_nritems) {
2625                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
2626                                                   leaf_data_end(root, right);
2627                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
2628                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
2629                                       btrfs_leaf_data(right) +
2630                                       leaf_data_end(root, right), push_space);
2631
2632                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
2633                               btrfs_item_nr_offset(push_items),
2634                              (btrfs_header_nritems(right) - push_items) *
2635                              sizeof(struct btrfs_item));
2636         }
2637         right_nritems -= push_items;
2638         btrfs_set_header_nritems(right, right_nritems);
2639         push_space = BTRFS_LEAF_DATA_SIZE(root);
2640         for (i = 0; i < right_nritems; i++) {
2641                 item = btrfs_item_nr(right, i);
2642
2643                 if (!right->map_token) {
2644                         map_extent_buffer(right, (unsigned long)item,
2645                                         sizeof(struct btrfs_item),
2646                                         &right->map_token, &right->kaddr,
2647                                         &right->map_start, &right->map_len,
2648                                         KM_USER1);
2649                 }
2650
2651                 push_space = push_space - btrfs_item_size(right, item);
2652                 btrfs_set_item_offset(right, item, push_space);
2653         }
2654         if (right->map_token) {
2655                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2656                 right->map_token = NULL;
2657         }
2658
2659         btrfs_mark_buffer_dirty(left);
2660         if (right_nritems)
2661                 btrfs_mark_buffer_dirty(right);
2662
2663         btrfs_item_key(right, &disk_key, 0);
2664         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
2665         if (wret)
2666                 ret = wret;
2667
2668         /* then fixup the leaf pointer in the path */
2669         if (path->slots[0] < push_items) {
2670                 path->slots[0] += old_left_nritems;
2671                 if (btrfs_header_nritems(path->nodes[0]) == 0)
2672                         clean_tree_block(trans, root, path->nodes[0]);
2673                 btrfs_tree_unlock(path->nodes[0]);
2674                 free_extent_buffer(path->nodes[0]);
2675                 path->nodes[0] = left;
2676                 path->slots[1] -= 1;
2677         } else {
2678                 btrfs_tree_unlock(left);
2679                 free_extent_buffer(left);
2680                 path->slots[0] -= push_items;
2681         }
2682         BUG_ON(path->slots[0] < 0);
2683         return ret;
2684 out:
2685         btrfs_tree_unlock(left);
2686         free_extent_buffer(left);
2687         return ret;
2688 }
2689
2690 /*
2691  * push some data in the path leaf to the left, trying to free up at
2692  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
2693  */
2694 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
2695                           *root, struct btrfs_path *path, int data_size,
2696                           int empty)
2697 {
2698         struct extent_buffer *right = path->nodes[0];
2699         struct extent_buffer *left;
2700         int slot;
2701         int free_space;
2702         u32 right_nritems;
2703         int ret = 0;
2704
2705         slot = path->slots[1];
2706         if (slot == 0)
2707                 return 1;
2708         if (!path->nodes[1])
2709                 return 1;
2710
2711         right_nritems = btrfs_header_nritems(right);
2712         if (right_nritems == 0)
2713                 return 1;
2714
2715         btrfs_assert_tree_locked(path->nodes[1]);
2716
2717         left = read_node_slot(root, path->nodes[1], slot - 1);
2718         btrfs_tree_lock(left);
2719         btrfs_set_lock_blocking(left);
2720
2721         free_space = btrfs_leaf_free_space(root, left);
2722         if (free_space < data_size) {
2723                 ret = 1;
2724                 goto out;
2725         }
2726
2727         /* cow and double check */
2728         ret = btrfs_cow_block(trans, root, left,
2729                               path->nodes[1], slot - 1, &left);
2730         if (ret) {
2731                 /* we hit -ENOSPC, but it isn't fatal here */
2732                 ret = 1;
2733                 goto out;
2734         }
2735
2736         free_space = btrfs_leaf_free_space(root, left);
2737         if (free_space < data_size) {
2738                 ret = 1;
2739                 goto out;
2740         }
2741
2742         return __push_leaf_left(trans, root, path, data_size,
2743                                empty, left, free_space, right_nritems);
2744 out:
2745         btrfs_tree_unlock(left);
2746         free_extent_buffer(left);
2747         return ret;
2748 }
2749
2750 /*
2751  * split the path's leaf in two, making sure there is at least data_size
2752  * available for the resulting leaf level of the path.
2753  *
2754  * returns 0 if all went well and < 0 on failure.
2755  */
2756 static noinline int copy_for_split(struct btrfs_trans_handle *trans,
2757                                struct btrfs_root *root,
2758                                struct btrfs_path *path,
2759                                struct extent_buffer *l,
2760                                struct extent_buffer *right,
2761                                int slot, int mid, int nritems)
2762 {
2763         int data_copy_size;
2764         int rt_data_off;
2765         int i;
2766         int ret = 0;
2767         int wret;
2768         struct btrfs_disk_key disk_key;
2769
2770         nritems = nritems - mid;
2771         btrfs_set_header_nritems(right, nritems);
2772         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
2773
2774         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2775                            btrfs_item_nr_offset(mid),
2776                            nritems * sizeof(struct btrfs_item));
2777
2778         copy_extent_buffer(right, l,
2779                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2780                      data_copy_size, btrfs_leaf_data(l) +
2781                      leaf_data_end(root, l), data_copy_size);
2782
2783         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2784                       btrfs_item_end_nr(l, mid);
2785
2786         for (i = 0; i < nritems; i++) {
2787                 struct btrfs_item *item = btrfs_item_nr(right, i);
2788                 u32 ioff;
2789
2790                 if (!right->map_token) {
2791                         map_extent_buffer(right, (unsigned long)item,
2792                                         sizeof(struct btrfs_item),
2793                                         &right->map_token, &right->kaddr,
2794                                         &right->map_start, &right->map_len,
2795                                         KM_USER1);
2796                 }
2797
2798                 ioff = btrfs_item_offset(right, item);
2799                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2800         }
2801
2802         if (right->map_token) {
2803                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2804                 right->map_token = NULL;
2805         }
2806
2807         btrfs_set_header_nritems(l, mid);
2808         ret = 0;
2809         btrfs_item_key(right, &disk_key, 0);
2810         wret = insert_ptr(trans, root, path, &disk_key, right->start,
2811                           path->slots[1] + 1, 1);
2812         if (wret)
2813                 ret = wret;
2814
2815         btrfs_mark_buffer_dirty(right);
2816         btrfs_mark_buffer_dirty(l);
2817         BUG_ON(path->slots[0] != slot);
2818
2819         if (mid <= slot) {
2820                 btrfs_tree_unlock(path->nodes[0]);
2821                 free_extent_buffer(path->nodes[0]);
2822                 path->nodes[0] = right;
2823                 path->slots[0] -= mid;
2824                 path->slots[1] += 1;
2825         } else {
2826                 btrfs_tree_unlock(right);
2827                 free_extent_buffer(right);
2828         }
2829
2830         BUG_ON(path->slots[0] < 0);
2831
2832         return ret;
2833 }
2834
2835 /*
2836  * split the path's leaf in two, making sure there is at least data_size
2837  * available for the resulting leaf level of the path.
2838  *
2839  * returns 0 if all went well and < 0 on failure.
2840  */
2841 static noinline int split_leaf(struct btrfs_trans_handle *trans,
2842                                struct btrfs_root *root,
2843                                struct btrfs_key *ins_key,
2844                                struct btrfs_path *path, int data_size,
2845                                int extend)
2846 {
2847         struct btrfs_disk_key disk_key;
2848         struct extent_buffer *l;
2849         u32 nritems;
2850         int mid;
2851         int slot;
2852         struct extent_buffer *right;
2853         int ret = 0;
2854         int wret;
2855         int split;
2856         int num_doubles = 0;
2857
2858         l = path->nodes[0];
2859         slot = path->slots[0];
2860         if (extend && data_size + btrfs_item_size_nr(l, slot) +
2861             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root))
2862                 return -EOVERFLOW;
2863
2864         /* first try to make some room by pushing left and right */
2865         if (data_size && ins_key->type != BTRFS_DIR_ITEM_KEY) {
2866                 wret = push_leaf_right(trans, root, path, data_size, 0);
2867                 if (wret < 0)
2868                         return wret;
2869                 if (wret) {
2870                         wret = push_leaf_left(trans, root, path, data_size, 0);
2871                         if (wret < 0)
2872                                 return wret;
2873                 }
2874                 l = path->nodes[0];
2875
2876                 /* did the pushes work? */
2877                 if (btrfs_leaf_free_space(root, l) >= data_size)
2878                         return 0;
2879         }
2880
2881         if (!path->nodes[1]) {
2882                 ret = insert_new_root(trans, root, path, 1);
2883                 if (ret)
2884                         return ret;
2885         }
2886 again:
2887         split = 1;
2888         l = path->nodes[0];
2889         slot = path->slots[0];
2890         nritems = btrfs_header_nritems(l);
2891         mid = (nritems + 1) / 2;
2892
2893         if (mid <= slot) {
2894                 if (nritems == 1 ||
2895                     leaf_space_used(l, mid, nritems - mid) + data_size >
2896                         BTRFS_LEAF_DATA_SIZE(root)) {
2897                         if (slot >= nritems) {
2898                                 split = 0;
2899                         } else {
2900                                 mid = slot;
2901                                 if (mid != nritems &&
2902                                     leaf_space_used(l, mid, nritems - mid) +
2903                                     data_size > BTRFS_LEAF_DATA_SIZE(root)) {
2904                                         split = 2;
2905                                 }
2906                         }
2907                 }
2908         } else {
2909                 if (leaf_space_used(l, 0, mid) + data_size >
2910                         BTRFS_LEAF_DATA_SIZE(root)) {
2911                         if (!extend && data_size && slot == 0) {
2912                                 split = 0;
2913                         } else if ((extend || !data_size) && slot == 0) {
2914                                 mid = 1;
2915                         } else {
2916                                 mid = slot;
2917                                 if (mid != nritems &&
2918                                     leaf_space_used(l, mid, nritems - mid) +
2919                                     data_size > BTRFS_LEAF_DATA_SIZE(root)) {
2920                                         split = 2 ;
2921                                 }
2922                         }
2923                 }
2924         }
2925
2926         if (split == 0)
2927                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
2928         else
2929                 btrfs_item_key(l, &disk_key, mid);
2930
2931         right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
2932                                         root->root_key.objectid,
2933                                         &disk_key, 0, l->start, 0);
2934         if (IS_ERR(right)) {
2935                 BUG_ON(1);
2936                 return PTR_ERR(right);
2937         }
2938
2939         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
2940         btrfs_set_header_bytenr(right, right->start);
2941         btrfs_set_header_generation(right, trans->transid);
2942         btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
2943         btrfs_set_header_owner(right, root->root_key.objectid);
2944         btrfs_set_header_level(right, 0);
2945         write_extent_buffer(right, root->fs_info->fsid,
2946                             (unsigned long)btrfs_header_fsid(right),
2947                             BTRFS_FSID_SIZE);
2948
2949         write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
2950                             (unsigned long)btrfs_header_chunk_tree_uuid(right),
2951                             BTRFS_UUID_SIZE);
2952
2953         if (split == 0) {
2954                 if (mid <= slot) {
2955                         btrfs_set_header_nritems(right, 0);
2956                         wret = insert_ptr(trans, root, path,
2957                                           &disk_key, right->start,
2958                                           path->slots[1] + 1, 1);
2959                         if (wret)
2960                                 ret = wret;
2961
2962                         btrfs_tree_unlock(path->nodes[0]);
2963                         free_extent_buffer(path->nodes[0]);
2964                         path->nodes[0] = right;
2965                         path->slots[0] = 0;
2966                         path->slots[1] += 1;
2967                 } else {
2968                         btrfs_set_header_nritems(right, 0);
2969                         wret = insert_ptr(trans, root, path,
2970                                           &disk_key,
2971                                           right->start,
2972                                           path->slots[1], 1);
2973                         if (wret)
2974                                 ret = wret;
2975                         btrfs_tree_unlock(path->nodes[0]);
2976                         free_extent_buffer(path->nodes[0]);
2977                         path->nodes[0] = right;
2978                         path->slots[0] = 0;
2979                         if (path->slots[1] == 0) {
2980                                 wret = fixup_low_keys(trans, root,
2981                                                 path, &disk_key, 1);
2982                                 if (wret)
2983                                         ret = wret;
2984                         }
2985                 }
2986                 btrfs_mark_buffer_dirty(right);
2987                 return ret;
2988         }
2989
2990         ret = copy_for_split(trans, root, path, l, right, slot, mid, nritems);
2991         BUG_ON(ret);
2992
2993         if (split == 2) {
2994                 BUG_ON(num_doubles != 0);
2995                 num_doubles++;
2996                 goto again;
2997         }
2998
2999         return ret;
3000 }
3001
3002 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3003                                          struct btrfs_root *root,
3004                                          struct btrfs_path *path, int ins_len)
3005 {
3006         struct btrfs_key key;
3007         struct extent_buffer *leaf;
3008         struct btrfs_file_extent_item *fi;
3009         u64 extent_len = 0;
3010         u32 item_size;
3011         int ret;
3012
3013         leaf = path->nodes[0];
3014         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3015
3016         BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3017                key.type != BTRFS_EXTENT_CSUM_KEY);
3018
3019         if (btrfs_leaf_free_space(root, leaf) >= ins_len)
3020                 return 0;
3021
3022         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3023         if (key.type == BTRFS_EXTENT_DATA_KEY) {
3024                 fi = btrfs_item_ptr(leaf, path->slots[0],
3025                                     struct btrfs_file_extent_item);
3026                 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3027         }
3028         btrfs_release_path(root, path);
3029
3030         path->keep_locks = 1;
3031         path->search_for_split = 1;
3032         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3033         path->search_for_split = 0;
3034         if (ret < 0)
3035                 goto err;
3036
3037         ret = -EAGAIN;
3038         leaf = path->nodes[0];
3039         /* if our item isn't there or got smaller, return now */
3040         if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0]))
3041                 goto err;
3042
3043         if (key.type == BTRFS_EXTENT_DATA_KEY) {
3044                 fi = btrfs_item_ptr(leaf, path->slots[0],
3045                                     struct btrfs_file_extent_item);
3046                 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3047                         goto err;
3048         }
3049
3050         btrfs_set_path_blocking(path);
3051         ret = split_leaf(trans, root, &key, path, ins_len, 1);
3052         BUG_ON(ret);
3053
3054         path->keep_locks = 0;
3055         btrfs_unlock_up_safe(path, 1);
3056         return 0;
3057 err:
3058         path->keep_locks = 0;
3059         return ret;
3060 }
3061
3062 static noinline int split_item(struct btrfs_trans_handle *trans,
3063                                struct btrfs_root *root,
3064                                struct btrfs_path *path,
3065                                struct btrfs_key *new_key,
3066                                unsigned long split_offset)
3067 {
3068         struct extent_buffer *leaf;
3069         struct btrfs_item *item;
3070         struct btrfs_item *new_item;
3071         int slot;
3072         char *buf;
3073         u32 nritems;
3074         u32 item_size;
3075         u32 orig_offset;
3076         struct btrfs_disk_key disk_key;
3077
3078         leaf = path->nodes[0];
3079         BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
3080
3081         btrfs_set_path_blocking(path);
3082
3083         item = btrfs_item_nr(leaf, path->slots[0]);
3084         orig_offset = btrfs_item_offset(leaf, item);
3085         item_size = btrfs_item_size(leaf, item);
3086
3087         buf = kmalloc(item_size, GFP_NOFS);
3088         if (!buf)
3089                 return -ENOMEM;
3090
3091         read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3092                             path->slots[0]), item_size);
3093
3094         slot = path->slots[0] + 1;
3095         nritems = btrfs_header_nritems(leaf);
3096         if (slot != nritems) {
3097                 /* shift the items */
3098                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
3099                                 btrfs_item_nr_offset(slot),
3100                                 (nritems - slot) * sizeof(struct btrfs_item));
3101         }
3102
3103         btrfs_cpu_key_to_disk(&disk_key, new_key);
3104         btrfs_set_item_key(leaf, &disk_key, slot);
3105
3106         new_item = btrfs_item_nr(leaf, slot);
3107
3108         btrfs_set_item_offset(leaf, new_item, orig_offset);
3109         btrfs_set_item_size(leaf, new_item, item_size - split_offset);
3110
3111         btrfs_set_item_offset(leaf, item,
3112                               orig_offset + item_size - split_offset);
3113         btrfs_set_item_size(leaf, item, split_offset);
3114
3115         btrfs_set_header_nritems(leaf, nritems + 1);
3116
3117         /* write the data for the start of the original item */
3118         write_extent_buffer(leaf, buf,
3119                             btrfs_item_ptr_offset(leaf, path->slots[0]),
3120                             split_offset);
3121
3122         /* write the data for the new item */
3123         write_extent_buffer(leaf, buf + split_offset,
3124                             btrfs_item_ptr_offset(leaf, slot),
3125                             item_size - split_offset);
3126         btrfs_mark_buffer_dirty(leaf);
3127
3128         BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
3129         kfree(buf);
3130         return 0;
3131 }
3132
3133 /*
3134  * This function splits a single item into two items,
3135  * giving 'new_key' to the new item and splitting the
3136  * old one at split_offset (from the start of the item).
3137  *
3138  * The path may be released by this operation.  After
3139  * the split, the path is pointing to the old item.  The
3140  * new item is going to be in the same node as the old one.
3141  *
3142  * Note, the item being split must be smaller enough to live alone on
3143  * a tree block with room for one extra struct btrfs_item
3144  *
3145  * This allows us to split the item in place, keeping a lock on the
3146  * leaf the entire time.
3147  */
3148 int btrfs_split_item(struct btrfs_trans_handle *trans,
3149                      struct btrfs_root *root,
3150                      struct btrfs_path *path,
3151                      struct btrfs_key *new_key,
3152                      unsigned long split_offset)
3153 {
3154         int ret;
3155         ret = setup_leaf_for_split(trans, root, path,
3156                                    sizeof(struct btrfs_item));
3157         if (ret)
3158                 return ret;
3159
3160         ret = split_item(trans, root, path, new_key, split_offset);
3161         return ret;
3162 }
3163
3164 /*
3165  * This function duplicate a item, giving 'new_key' to the new item.
3166  * It guarantees both items live in the same tree leaf and the new item
3167  * is contiguous with the original item.
3168  *
3169  * This allows us to split file extent in place, keeping a lock on the
3170  * leaf the entire time.
3171  */
3172 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
3173                          struct btrfs_root *root,
3174                          struct btrfs_path *path,
3175                          struct btrfs_key *new_key)
3176 {
3177         struct extent_buffer *leaf;
3178         int ret;
3179         u32 item_size;
3180
3181         leaf = path->nodes[0];
3182         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3183         ret = setup_leaf_for_split(trans, root, path,
3184                                    item_size + sizeof(struct btrfs_item));
3185         if (ret)
3186                 return ret;
3187
3188         path->slots[0]++;
3189         ret = setup_items_for_insert(trans, root, path, new_key, &item_size,
3190                                      item_size, item_size +
3191                                      sizeof(struct btrfs_item), 1);
3192         BUG_ON(ret);
3193
3194         leaf = path->nodes[0];
3195         memcpy_extent_buffer(leaf,
3196                              btrfs_item_ptr_offset(leaf, path->slots[0]),
3197                              btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
3198                              item_size);
3199         return 0;
3200 }
3201
3202 /*
3203  * make the item pointed to by the path smaller.  new_size indicates
3204  * how small to make it, and from_end tells us if we just chop bytes
3205  * off the end of the item or if we shift the item to chop bytes off
3206  * the front.
3207  */
3208 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
3209                         struct btrfs_root *root,
3210                         struct btrfs_path *path,
3211                         u32 new_size, int from_end)
3212 {
3213         int ret = 0;
3214         int slot;
3215         int slot_orig;
3216         struct extent_buffer *leaf;
3217         struct btrfs_item *item;
3218         u32 nritems;
3219         unsigned int data_end;
3220         unsigned int old_data_start;
3221         unsigned int old_size;
3222         unsigned int size_diff;
3223         int i;
3224
3225         slot_orig = path->slots[0];
3226         leaf = path->nodes[0];
3227         slot = path->slots[0];
3228
3229         old_size = btrfs_item_size_nr(leaf, slot);
3230         if (old_size == new_size)
3231                 return 0;
3232
3233         nritems = btrfs_header_nritems(leaf);
3234         data_end = leaf_data_end(root, leaf);
3235
3236         old_data_start = btrfs_item_offset_nr(leaf, slot);
3237
3238         size_diff = old_size - new_size;
3239
3240         BUG_ON(slot < 0);
3241         BUG_ON(slot >= nritems);
3242
3243         /*
3244          * item0..itemN ... dataN.offset..dataN.size .. data0.size
3245          */
3246         /* first correct the data pointers */
3247         for (i = slot; i < nritems; i++) {
3248                 u32 ioff;
3249                 item = btrfs_item_nr(leaf, i);
3250
3251                 if (!leaf->map_token) {
3252                         map_extent_buffer(leaf, (unsigned long)item,
3253                                         sizeof(struct btrfs_item),
3254                                         &leaf->map_token, &leaf->kaddr,
3255                                         &leaf->map_start, &leaf->map_len,
3256                                         KM_USER1);
3257                 }
3258
3259                 ioff = btrfs_item_offset(leaf, item);
3260                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
3261         }
3262
3263         if (leaf->map_token) {
3264                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3265                 leaf->map_token = NULL;
3266         }
3267
3268         /* shift the data */
3269         if (from_end) {
3270                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3271                               data_end + size_diff, btrfs_leaf_data(leaf) +
3272                               data_end, old_data_start + new_size - data_end);
3273         } else {
3274                 struct btrfs_disk_key disk_key;
3275                 u64 offset;
3276
3277                 btrfs_item_key(leaf, &disk_key, slot);
3278
3279                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
3280                         unsigned long ptr;
3281                         struct btrfs_file_extent_item *fi;
3282
3283                         fi = btrfs_item_ptr(leaf, slot,
3284                                             struct btrfs_file_extent_item);
3285                         fi = (struct btrfs_file_extent_item *)(
3286                              (unsigned long)fi - size_diff);
3287
3288                         if (btrfs_file_extent_type(leaf, fi) ==
3289                             BTRFS_FILE_EXTENT_INLINE) {
3290                                 ptr = btrfs_item_ptr_offset(leaf, slot);
3291                                 memmove_extent_buffer(leaf, ptr,
3292                                       (unsigned long)fi,
3293                                       offsetof(struct btrfs_file_extent_item,
3294                                                  disk_bytenr));
3295                         }
3296                 }
3297
3298                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3299                               data_end + size_diff, btrfs_leaf_data(leaf) +
3300                               data_end, old_data_start - data_end);
3301
3302                 offset = btrfs_disk_key_offset(&disk_key);
3303                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
3304                 btrfs_set_item_key(leaf, &disk_key, slot);
3305                 if (slot == 0)
3306                         fixup_low_keys(trans, root, path, &disk_key, 1);
3307         }
3308
3309         item = btrfs_item_nr(leaf, slot);
3310         btrfs_set_item_size(leaf, item, new_size);
3311         btrfs_mark_buffer_dirty(leaf);
3312
3313         ret = 0;
3314         if (btrfs_leaf_free_space(root, leaf) < 0) {
3315                 btrfs_print_leaf(root, leaf);
3316                 BUG();
3317         }
3318         return ret;
3319 }
3320
3321 /*
3322  * make the item pointed to by the path bigger, data_size is the new size.
3323  */
3324 int btrfs_extend_item(struct btrfs_trans_handle *trans,
3325                       struct btrfs_root *root, struct btrfs_path *path,
3326                       u32 data_size)
3327 {
3328         int ret = 0;
3329         int slot;
3330         int slot_orig;
3331         struct extent_buffer *leaf;
3332         struct btrfs_item *item;
3333         u32 nritems;
3334         unsigned int data_end;
3335         unsigned int old_data;
3336         unsigned int old_size;
3337         int i;
3338
3339         slot_orig = path->slots[0];
3340         leaf = path->nodes[0];
3341
3342         nritems = btrfs_header_nritems(leaf);
3343         data_end = leaf_data_end(root, leaf);
3344
3345         if (btrfs_leaf_free_space(root, leaf) < data_size) {
3346                 btrfs_print_leaf(root, leaf);
3347                 BUG();
3348         }
3349         slot = path->slots[0];
3350         old_data = btrfs_item_end_nr(leaf, slot);
3351
3352         BUG_ON(slot < 0);
3353         if (slot >= nritems) {
3354                 btrfs_print_leaf(root, leaf);
3355                 printk(KERN_CRIT "slot %d too large, nritems %d\n",
3356                        slot, nritems);
3357                 BUG_ON(1);
3358         }
3359
3360         /*
3361          * item0..itemN ... dataN.offset..dataN.size .. data0.size
3362          */
3363         /* first correct the data pointers */
3364         for (i = slot; i < nritems; i++) {
3365                 u32 ioff;
3366                 item = btrfs_item_nr(leaf, i);
3367
3368                 if (!leaf->map_token) {
3369                         map_extent_buffer(leaf, (unsigned long)item,
3370                                         sizeof(struct btrfs_item),
3371                                         &leaf->map_token, &leaf->kaddr,
3372                                         &leaf->map_start, &leaf->map_len,
3373                                         KM_USER1);
3374                 }
3375                 ioff = btrfs_item_offset(leaf, item);
3376                 btrfs_set_item_offset(leaf, item, ioff - data_size);
3377         }
3378
3379         if (leaf->map_token) {
3380                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3381                 leaf->map_token = NULL;
3382         }
3383
3384         /* shift the data */
3385         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3386                       data_end - data_size, btrfs_leaf_data(leaf) +
3387                       data_end, old_data - data_end);
3388
3389         data_end = old_data;
3390         old_size = btrfs_item_size_nr(leaf, slot);
3391         item = btrfs_item_nr(leaf, slot);
3392         btrfs_set_item_size(leaf, item, old_size + data_size);
3393         btrfs_mark_buffer_dirty(leaf);
3394
3395         ret = 0;
3396         if (btrfs_leaf_free_space(root, leaf) < 0) {
3397                 btrfs_print_leaf(root, leaf);
3398                 BUG();
3399         }
3400         return ret;
3401 }
3402
3403 /*
3404  * Given a key and some data, insert items into the tree.
3405  * This does all the path init required, making room in the tree if needed.
3406  * Returns the number of keys that were inserted.
3407  */
3408 int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
3409                             struct btrfs_root *root,
3410                             struct btrfs_path *path,
3411                             struct btrfs_key *cpu_key, u32 *data_size,
3412                             int nr)
3413 {
3414         struct extent_buffer *leaf;
3415         struct btrfs_item *item;
3416         int ret = 0;
3417         int slot;
3418         int i;
3419         u32 nritems;
3420         u32 total_data = 0;
3421         u32 total_size = 0;
3422         unsigned int data_end;
3423         struct btrfs_disk_key disk_key;
3424         struct btrfs_key found_key;
3425
3426         for (i = 0; i < nr; i++) {
3427                 if (total_size + data_size[i] + sizeof(struct btrfs_item) >
3428                     BTRFS_LEAF_DATA_SIZE(root)) {
3429                         break;
3430                         nr = i;
3431                 }
3432                 total_data += data_size[i];
3433                 total_size += data_size[i] + sizeof(struct btrfs_item);
3434         }
3435         BUG_ON(nr == 0);
3436
3437         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
3438         if (ret == 0)
3439                 return -EEXIST;
3440         if (ret < 0)
3441                 goto out;
3442
3443         leaf = path->nodes[0];
3444
3445         nritems = btrfs_header_nritems(leaf);
3446         data_end = leaf_data_end(root, leaf);
3447
3448         if (btrfs_leaf_free_space(root, leaf) < total_size) {
3449                 for (i = nr; i >= 0; i--) {
3450                         total_data -= data_size[i];
3451                         total_size -= data_size[i] + sizeof(struct btrfs_item);
3452                         if (total_size < btrfs_leaf_free_space(root, leaf))
3453                                 break;
3454                 }
3455                 nr = i;
3456         }
3457
3458         slot = path->slots[0];
3459         BUG_ON(slot < 0);
3460
3461         if (slot != nritems) {
3462                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
3463
3464                 item = btrfs_item_nr(leaf, slot);
3465                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
3466
3467                 /* figure out how many keys we can insert in here */
3468                 total_data = data_size[0];
3469                 for (i = 1; i < nr; i++) {
3470                         if (btrfs_comp_cpu_keys(&found_key, cpu_key + i) <= 0)
3471                                 break;
3472                         total_data += data_size[i];
3473                 }
3474                 nr = i;
3475
3476                 if (old_data < data_end) {
3477                         btrfs_print_leaf(root, leaf);
3478                         printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
3479                                slot, old_data, data_end);
3480                         BUG_ON(1);
3481                 }
3482                 /*
3483                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
3484                  */
3485                 /* first correct the data pointers */
3486                 WARN_ON(leaf->map_token);
3487                 for (i = slot; i < nritems; i++) {
3488                         u32 ioff;
3489
3490                         item = btrfs_item_nr(leaf, i);
3491                         if (!leaf->map_token) {
3492                                 map_extent_buffer(leaf, (unsigned long)item,
3493                                         sizeof(struct btrfs_item),
3494                                         &leaf->map_token, &leaf->kaddr,
3495                                         &leaf->map_start, &leaf->map_len,
3496                                         KM_USER1);
3497                         }
3498
3499                         ioff = btrfs_item_offset(leaf, item);
3500                         btrfs_set_item_offset(leaf, item, ioff - total_data);
3501                 }
3502                 if (leaf->map_token) {
3503                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3504                         leaf->map_token = NULL;
3505                 }
3506
3507                 /* shift the items */
3508                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
3509                               btrfs_item_nr_offset(slot),
3510                               (nritems - slot) * sizeof(struct btrfs_item));
3511
3512                 /* shift the data */
3513                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3514                               data_end - total_data, btrfs_leaf_data(leaf) +
3515                               data_end, old_data - data_end);
3516                 data_end = old_data;
3517         } else {
3518                 /*
3519                  * this sucks but it has to be done, if we are inserting at
3520                  * the end of the leaf only insert 1 of the items, since we
3521                  * have no way of knowing whats on the next leaf and we'd have
3522                  * to drop our current locks to figure it out
3523                  */
3524                 nr = 1;
3525         }
3526
3527         /* setup the item for the new data */
3528         for (i = 0; i < nr; i++) {
3529                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
3530                 btrfs_set_item_key(leaf, &disk_key, slot + i);
3531                 item = btrfs_item_nr(leaf, slot + i);
3532                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
3533                 data_end -= data_size[i];
3534                 btrfs_set_item_size(leaf, item, data_size[i]);
3535         }
3536         btrfs_set_header_nritems(leaf, nritems + nr);
3537         btrfs_mark_buffer_dirty(leaf);
3538
3539         ret = 0;
3540         if (slot == 0) {
3541                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
3542                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
3543         }
3544
3545         if (btrfs_leaf_free_space(root, leaf) < 0) {
3546                 btrfs_print_leaf(root, leaf);
3547                 BUG();
3548         }
3549 out:
3550         if (!ret)
3551                 ret = nr;
3552         return ret;
3553 }
3554
3555 /*
3556  * this is a helper for btrfs_insert_empty_items, the main goal here is
3557  * to save stack depth by doing the bulk of the work in a function
3558  * that doesn't call btrfs_search_slot
3559  */
3560 static noinline_for_stack int
3561 setup_items_for_insert(struct btrfs_trans_handle *trans,
3562                       struct btrfs_root *root, struct btrfs_path *path,
3563                       struct btrfs_key *cpu_key, u32 *data_size,
3564                       u32 total_data, u32 total_size, int nr)
3565 {
3566         struct btrfs_item *item;
3567         int i;
3568         u32 nritems;
3569         unsigned int data_end;
3570         struct btrfs_disk_key disk_key;
3571         int ret;
3572         struct extent_buffer *leaf;
3573         int slot;
3574
3575         leaf = path->nodes[0];
3576         slot = path->slots[0];
3577
3578         nritems = btrfs_header_nritems(leaf);
3579         data_end = leaf_data_end(root, leaf);
3580
3581         if (btrfs_leaf_free_space(root, leaf) < total_size) {
3582                 btrfs_print_leaf(root, leaf);
3583                 printk(KERN_CRIT "not enough freespace need %u have %d\n",
3584                        total_size, btrfs_leaf_free_space(root, leaf));
3585                 BUG();
3586         }
3587
3588         if (slot != nritems) {
3589                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
3590
3591                 if (old_data < data_end) {
3592                         btrfs_print_leaf(root, leaf);
3593                         printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
3594                                slot, old_data, data_end);
3595                         BUG_ON(1);
3596                 }
3597                 /*
3598                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
3599                  */
3600                 /* first correct the data pointers */
3601                 WARN_ON(leaf->map_token);
3602                 for (i = slot; i < nritems; i++) {
3603                         u32 ioff;
3604
3605                         item = btrfs_item_nr(leaf, i);
3606                         if (!leaf->map_token) {
3607                                 map_extent_buffer(leaf, (unsigned long)item,
3608                                         sizeof(struct btrfs_item),
3609                                         &leaf->map_token, &leaf->kaddr,
3610                                         &leaf->map_start, &leaf->map_len,
3611                                         KM_USER1);
3612                         }
3613
3614                         ioff = btrfs_item_offset(leaf, item);
3615                         btrfs_set_item_offset(leaf, item, ioff - total_data);
3616                 }
3617                 if (leaf->map_token) {
3618                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3619                         leaf->map_token = NULL;
3620                 }
3621
3622                 /* shift the items */
3623                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
3624                               btrfs_item_nr_offset(slot),
3625                               (nritems - slot) * sizeof(struct btrfs_item));
3626
3627                 /* shift the data */
3628                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3629                               data_end - total_data, btrfs_leaf_data(leaf) +
3630                               data_end, old_data - data_end);
3631                 data_end = old_data;
3632         }
3633
3634         /* setup the item for the new data */
3635         for (i = 0; i < nr; i++) {
3636                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
3637                 btrfs_set_item_key(leaf, &disk_key, slot + i);
3638                 item = btrfs_item_nr(leaf, slot + i);
3639                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
3640                 data_end -= data_size[i];
3641                 btrfs_set_item_size(leaf, item, data_size[i]);
3642         }
3643
3644         btrfs_set_header_nritems(leaf, nritems + nr);
3645
3646         ret = 0;
3647         if (slot == 0) {
3648                 struct btrfs_disk_key disk_key;
3649                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
3650                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
3651         }
3652         btrfs_unlock_up_safe(path, 1);
3653         btrfs_mark_buffer_dirty(leaf);
3654
3655         if (btrfs_leaf_free_space(root, leaf) < 0) {
3656                 btrfs_print_leaf(root, leaf);
3657                 BUG();
3658         }
3659         return ret;
3660 }
3661
3662 /*
3663  * Given a key and some data, insert items into the tree.
3664  * This does all the path init required, making room in the tree if needed.
3665  */
3666 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
3667                             struct btrfs_root *root,
3668                             struct btrfs_path *path,
3669                             struct btrfs_key *cpu_key, u32 *data_size,
3670                             int nr)
3671 {
3672         struct extent_buffer *leaf;
3673         int ret = 0;
3674         int slot;
3675         int i;
3676         u32 total_size = 0;
3677         u32 total_data = 0;
3678
3679         for (i = 0; i < nr; i++)
3680                 total_data += data_size[i];
3681
3682         total_size = total_data + (nr * sizeof(struct btrfs_item));
3683         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
3684         if (ret == 0)
3685                 return -EEXIST;
3686         if (ret < 0)
3687                 goto out;
3688
3689         leaf = path->nodes[0];
3690         slot = path->slots[0];
3691         BUG_ON(slot < 0);
3692
3693         ret = setup_items_for_insert(trans, root, path, cpu_key, data_size,
3694                                total_data, total_size, nr);
3695
3696 out:
3697         return ret;
3698 }
3699
3700 /*
3701  * Given a key and some data, insert an item into the tree.
3702  * This does all the path init required, making room in the tree if needed.
3703  */
3704 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
3705                       *root, struct btrfs_key *cpu_key, void *data, u32
3706                       data_size)
3707 {
3708         int ret = 0;
3709         struct btrfs_path *path;
3710         struct extent_buffer *leaf;
3711         unsigned long ptr;
3712
3713         path = btrfs_alloc_path();
3714         BUG_ON(!path);
3715         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
3716         if (!ret) {
3717                 leaf = path->nodes[0];
3718                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
3719                 write_extent_buffer(leaf, data, ptr, data_size);
3720                 btrfs_mark_buffer_dirty(leaf);
3721         }
3722         btrfs_free_path(path);
3723         return ret;
3724 }
3725
3726 /*
3727  * delete the pointer from a given node.
3728  *
3729  * the tree should have been previously balanced so the deletion does not
3730  * empty a node.
3731  */
3732 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3733                    struct btrfs_path *path, int level, int slot)
3734 {
3735         struct extent_buffer *parent = path->nodes[level];
3736         u32 nritems;
3737         int ret = 0;
3738         int wret;
3739
3740         nritems = btrfs_header_nritems(parent);
3741         if (slot != nritems - 1) {
3742                 memmove_extent_buffer(parent,
3743                               btrfs_node_key_ptr_offset(slot),
3744                               btrfs_node_key_ptr_offset(slot + 1),
3745                               sizeof(struct btrfs_key_ptr) *
3746                               (nritems - slot - 1));
3747         }
3748         nritems--;
3749         btrfs_set_header_nritems(parent, nritems);
3750         if (nritems == 0 && parent == root->node) {
3751                 BUG_ON(btrfs_header_level(root->node) != 1);
3752                 /* just turn the root into a leaf and break */
3753                 btrfs_set_header_level(root->node, 0);
3754         } else if (slot == 0) {
3755                 struct btrfs_disk_key disk_key;
3756
3757                 btrfs_node_key(parent, &disk_key, 0);
3758                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
3759                 if (wret)
3760                         ret = wret;
3761         }
3762         btrfs_mark_buffer_dirty(parent);
3763         return ret;
3764 }
3765
3766 /*
3767  * a helper function to delete the leaf pointed to by path->slots[1] and
3768  * path->nodes[1].
3769  *
3770  * This deletes the pointer in path->nodes[1] and frees the leaf
3771  * block extent.  zero is returned if it all worked out, < 0 otherwise.
3772  *
3773  * The path must have already been setup for deleting the leaf, including
3774  * all the proper balancing.  path->nodes[1] must be locked.
3775  */
3776 static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
3777                                    struct btrfs_root *root,
3778                                    struct btrfs_path *path,
3779                                    struct extent_buffer *leaf)
3780 {
3781         int ret;
3782
3783         WARN_ON(btrfs_header_generation(leaf) != trans->transid);
3784         ret = del_ptr(trans, root, path, 1, path->slots[1]);
3785         if (ret)
3786                 return ret;
3787
3788         /*
3789          * btrfs_free_extent is expensive, we want to make sure we
3790          * aren't holding any locks when we call it
3791          */
3792         btrfs_unlock_up_safe(path, 0);
3793
3794         ret = btrfs_free_tree_block(trans, root, leaf->start, leaf->len,
3795                                     0, root->root_key.objectid, 0);
3796         return ret;
3797 }
3798 /*
3799  * delete the item at the leaf level in path.  If that empties
3800  * the leaf, remove it from the tree
3801  */
3802 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3803                     struct btrfs_path *path, int slot, int nr)
3804 {
3805         struct extent_buffer *leaf;
3806         struct btrfs_item *item;
3807         int last_off;
3808         int dsize = 0;
3809         int ret = 0;
3810         int wret;
3811         int i;
3812         u32 nritems;
3813
3814         leaf = path->nodes[0];
3815         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
3816
3817         for (i = 0; i < nr; i++)
3818                 dsize += btrfs_item_size_nr(leaf, slot + i);
3819
3820         nritems = btrfs_header_nritems(leaf);
3821
3822         if (slot + nr != nritems) {
3823                 int data_end = leaf_data_end(root, leaf);
3824
3825                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3826                               data_end + dsize,
3827                               btrfs_leaf_data(leaf) + data_end,
3828                               last_off - data_end);
3829
3830                 for (i = slot + nr; i < nritems; i++) {
3831                         u32 ioff;
3832
3833                         item = btrfs_item_nr(leaf, i);
3834                         if (!leaf->map_token) {
3835                                 map_extent_buffer(leaf, (unsigned long)item,
3836                                         sizeof(struct btrfs_item),
3837                                         &leaf->map_token, &leaf->kaddr,
3838                                         &leaf->map_start, &leaf->map_len,
3839                                         KM_USER1);
3840                         }
3841                         ioff = btrfs_item_offset(leaf, item);
3842                         btrfs_set_item_offset(leaf, item, ioff + dsize);
3843                 }
3844
3845                 if (leaf->map_token) {
3846                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3847                         leaf->map_token = NULL;
3848                 }
3849
3850                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
3851                               btrfs_item_nr_offset(slot + nr),
3852                               sizeof(struct btrfs_item) *
3853                               (nritems - slot - nr));
3854         }
3855         btrfs_set_header_nritems(leaf, nritems - nr);
3856         nritems -= nr;
3857
3858         /* delete the leaf if we've emptied it */
3859         if (nritems == 0) {
3860                 if (leaf == root->node) {
3861                         btrfs_set_header_level(leaf, 0);
3862                 } else {
3863                         ret = btrfs_del_leaf(trans, root, path, leaf);
3864                         BUG_ON(ret);
3865                 }
3866         } else {
3867                 int used = leaf_space_used(leaf, 0, nritems);
3868                 if (slot == 0) {
3869                         struct btrfs_disk_key disk_key;
3870
3871                         btrfs_item_key(leaf, &disk_key, 0);
3872                         wret = fixup_low_keys(trans, root, path,
3873                                               &disk_key, 1);
3874                         if (wret)
3875                                 ret = wret;
3876                 }
3877
3878                 /* delete the leaf if it is mostly empty */
3879                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
3880                         /* push_leaf_left fixes the path.
3881                          * make sure the path still points to our leaf
3882                          * for possible call to del_ptr below
3883                          */
3884                         slot = path->slots[1];
3885                         extent_buffer_get(leaf);
3886
3887                         btrfs_set_path_blocking(path);
3888                         wret = push_leaf_left(trans, root, path, 1, 1);
3889                         if (wret < 0 && wret != -ENOSPC)
3890                                 ret = wret;
3891
3892                         if (path->nodes[0] == leaf &&
3893                             btrfs_header_nritems(leaf)) {
3894                                 wret = push_leaf_right(trans, root, path, 1, 1);
3895                                 if (wret < 0 && wret != -ENOSPC)
3896                                         ret = wret;
3897                         }
3898
3899                         if (btrfs_header_nritems(leaf) == 0) {
3900                                 path->slots[1] = slot;
3901                                 ret = btrfs_del_leaf(trans, root, path, leaf);
3902                                 BUG_ON(ret);
3903                                 free_extent_buffer(leaf);
3904                         } else {
3905                                 /* if we're still in the path, make sure
3906                                  * we're dirty.  Otherwise, one of the
3907                                  * push_leaf functions must have already
3908                                  * dirtied this buffer
3909                                  */
3910                                 if (path->nodes[0] == leaf)
3911                                         btrfs_mark_buffer_dirty(leaf);
3912                                 free_extent_buffer(leaf);
3913                         }
3914                 } else {
3915                         btrfs_mark_buffer_dirty(leaf);
3916                 }
3917         }
3918         return ret;
3919 }
3920
3921 /*
3922  * search the tree again to find a leaf with lesser keys
3923  * returns 0 if it found something or 1 if there are no lesser leaves.
3924  * returns < 0 on io errors.
3925  *
3926  * This may release the path, and so you may lose any locks held at the
3927  * time you call it.
3928  */
3929 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
3930 {
3931         struct btrfs_key key;
3932         struct btrfs_disk_key found_key;
3933         int ret;
3934
3935         btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
3936
3937         if (key.offset > 0)
3938                 key.offset--;
3939         else if (key.type > 0)
3940                 key.type--;
3941         else if (key.objectid > 0)
3942                 key.objectid--;
3943         else
3944                 return 1;
3945
3946         btrfs_release_path(root, path);
3947         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3948         if (ret < 0)
3949                 return ret;
3950         btrfs_item_key(path->nodes[0], &found_key, 0);
3951         ret = comp_keys(&found_key, &key);
3952         if (ret < 0)
3953                 return 0;
3954         return 1;
3955 }
3956
3957 /*
3958  * A helper function to walk down the tree starting at min_key, and looking
3959  * for nodes or leaves that are either in cache or have a minimum
3960  * transaction id.  This is used by the btree defrag code, and tree logging
3961  *
3962  * This does not cow, but it does stuff the starting key it finds back
3963  * into min_key, so you can call btrfs_search_slot with cow=1 on the
3964  * key and get a writable path.
3965  *
3966  * This does lock as it descends, and path->keep_locks should be set
3967  * to 1 by the caller.
3968  *
3969  * This honors path->lowest_level to prevent descent past a given level
3970  * of the tree.
3971  *
3972  * min_trans indicates the oldest transaction that you are interested
3973  * in walking through.  Any nodes or leaves older than min_trans are
3974  * skipped over (without reading them).
3975  *
3976  * returns zero if something useful was found, < 0 on error and 1 if there
3977  * was nothing in the tree that matched the search criteria.
3978  */
3979 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
3980                          struct btrfs_key *max_key,
3981                          struct btrfs_path *path, int cache_only,
3982                          u64 min_trans)
3983 {
3984         struct extent_buffer *cur;
3985         struct btrfs_key found_key;
3986         int slot;
3987         int sret;
3988         u32 nritems;
3989         int level;
3990         int ret = 1;
3991
3992         WARN_ON(!path->keep_locks);
3993 again:
3994         cur = btrfs_lock_root_node(root);
3995         level = btrfs_header_level(cur);
3996         WARN_ON(path->nodes[level]);
3997         path->nodes[level] = cur;
3998         path->locks[level] = 1;
3999
4000         if (btrfs_header_generation(cur) < min_trans) {
4001                 ret = 1;
4002                 goto out;
4003         }
4004         while (1) {
4005                 nritems = btrfs_header_nritems(cur);
4006                 level = btrfs_header_level(cur);
4007                 sret = bin_search(cur, min_key, level, &slot);
4008
4009                 /* at the lowest level, we're done, setup the path and exit */
4010                 if (level == path->lowest_level) {
4011                         if (slot >= nritems)
4012                                 goto find_next_key;
4013                         ret = 0;
4014                         path->slots[level] = slot;
4015                         btrfs_item_key_to_cpu(cur, &found_key, slot);
4016                         goto out;
4017                 }
4018                 if (sret && slot > 0)
4019                         slot--;
4020                 /*
4021                  * check this node pointer against the cache_only and
4022                  * min_trans parameters.  If it isn't in cache or is too
4023                  * old, skip to the next one.
4024                  */
4025                 while (slot < nritems) {
4026                         u64 blockptr;
4027                         u64 gen;
4028                         struct extent_buffer *tmp;
4029                         struct btrfs_disk_key disk_key;
4030
4031                         blockptr = btrfs_node_blockptr(cur, slot);
4032                         gen = btrfs_node_ptr_generation(cur, slot);
4033                         if (gen < min_trans) {
4034                                 slot++;
4035                                 continue;
4036                         }
4037                         if (!cache_only)
4038                                 break;
4039
4040                         if (max_key) {
4041                                 btrfs_node_key(cur, &disk_key, slot);
4042                                 if (comp_keys(&disk_key, max_key) >= 0) {
4043                                         ret = 1;
4044                                         goto out;
4045                                 }
4046                         }
4047
4048                         tmp = btrfs_find_tree_block(root, blockptr,
4049                                             btrfs_level_size(root, level - 1));
4050
4051                         if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
4052                                 free_extent_buffer(tmp);
4053                                 break;
4054                         }
4055                         if (tmp)
4056                                 free_extent_buffer(tmp);
4057                         slot++;
4058                 }
4059 find_next_key:
4060                 /*
4061                  * we didn't find a candidate key in this node, walk forward
4062                  * and find another one
4063                  */
4064                 if (slot >= nritems) {
4065                         path->slots[level] = slot;
4066                         btrfs_set_path_blocking(path);
4067                         sret = btrfs_find_next_key(root, path, min_key, level,
4068                                                   cache_only, min_trans);
4069                         if (sret == 0) {
4070                                 btrfs_release_path(root, path);
4071                                 goto again;
4072                         } else {
4073                                 goto out;
4074                         }
4075                 }
4076                 /* save our key for returning back */
4077                 btrfs_node_key_to_cpu(cur, &found_key, slot);
4078                 path->slots[level] = slot;
4079                 if (level == path->lowest_level) {
4080                         ret = 0;
4081                         unlock_up(path, level, 1);
4082                         goto out;
4083                 }
4084                 btrfs_set_path_blocking(path);
4085                 cur = read_node_slot(root, cur, slot);
4086
4087                 btrfs_tree_lock(cur);
4088
4089                 path->locks[level - 1] = 1;
4090                 path->nodes[level - 1] = cur;
4091                 unlock_up(path, level, 1);
4092                 btrfs_clear_path_blocking(path, NULL);
4093         }
4094 out:
4095         if (ret == 0)
4096                 memcpy(min_key, &found_key, sizeof(found_key));
4097         btrfs_set_path_blocking(path);
4098         return ret;
4099 }
4100
4101 /*
4102  * this is similar to btrfs_next_leaf, but does not try to preserve
4103  * and fixup the path.  It looks for and returns the next key in the
4104  * tree based on the current path and the cache_only and min_trans
4105  * parameters.
4106  *
4107  * 0 is returned if another key is found, < 0 if there are any errors
4108  * and 1 is returned if there are no higher keys in the tree
4109  *
4110  * path->keep_locks should be set to 1 on the search made before
4111  * calling this function.
4112  */
4113 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4114                         struct btrfs_key *key, int level,
4115                         int cache_only, u64 min_trans)
4116 {
4117         int slot;
4118         struct extent_buffer *c;
4119
4120         WARN_ON(!path->keep_locks);
4121         while (level < BTRFS_MAX_LEVEL) {
4122                 if (!path->nodes[level])
4123                         return 1;
4124
4125                 slot = path->slots[level] + 1;
4126                 c = path->nodes[level];
4127 next:
4128                 if (slot >= btrfs_header_nritems(c)) {
4129                         int ret;
4130                         int orig_lowest;
4131                         struct btrfs_key cur_key;
4132                         if (level + 1 >= BTRFS_MAX_LEVEL ||
4133                             !path->nodes[level + 1])
4134                                 return 1;
4135
4136                         if (path->locks[level + 1]) {
4137                                 level++;
4138                                 continue;
4139                         }
4140
4141                         slot = btrfs_header_nritems(c) - 1;
4142                         if (level == 0)
4143                                 btrfs_item_key_to_cpu(c, &cur_key, slot);
4144                         else
4145                                 btrfs_node_key_to_cpu(c, &cur_key, slot);
4146
4147                         orig_lowest = path->lowest_level;
4148                         btrfs_release_path(root, path);
4149                         path->lowest_level = level;
4150                         ret = btrfs_search_slot(NULL, root, &cur_key, path,
4151                                                 0, 0);
4152                         path->lowest_level = orig_lowest;
4153                         if (ret < 0)
4154                                 return ret;
4155
4156                         c = path->nodes[level];
4157                         slot = path->slots[level];
4158                         if (ret == 0)
4159                                 slot++;
4160                         goto next;
4161                 }
4162
4163                 if (level == 0)
4164                         btrfs_item_key_to_cpu(c, key, slot);
4165                 else {
4166                         u64 blockptr = btrfs_node_blockptr(c, slot);
4167                         u64 gen = btrfs_node_ptr_generation(c, slot);
4168
4169                         if (cache_only) {
4170                                 struct extent_buffer *cur;
4171                                 cur = btrfs_find_tree_block(root, blockptr,
4172                                             btrfs_level_size(root, level - 1));
4173                                 if (!cur || !btrfs_buffer_uptodate(cur, gen)) {
4174                                         slot++;
4175                                         if (cur)
4176                                                 free_extent_buffer(cur);
4177                                         goto next;
4178                                 }
4179                                 free_extent_buffer(cur);
4180                         }
4181                         if (gen < min_trans) {
4182                                 slot++;
4183                                 goto next;
4184                         }
4185                         btrfs_node_key_to_cpu(c, key, slot);
4186                 }
4187                 return 0;
4188         }
4189         return 1;
4190 }
4191
4192 /*
4193  * search the tree again to find a leaf with greater keys
4194  * returns 0 if it found something or 1 if there are no greater leaves.
4195  * returns < 0 on io errors.
4196  */
4197 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
4198 {
4199         int slot;
4200         int level;
4201         struct extent_buffer *c;
4202         struct extent_buffer *next;
4203         struct btrfs_key key;
4204         u32 nritems;
4205         int ret;
4206         int old_spinning = path->leave_spinning;
4207         int force_blocking = 0;
4208
4209         nritems = btrfs_header_nritems(path->nodes[0]);
4210         if (nritems == 0)
4211                 return 1;
4212
4213         /*
4214          * we take the blocks in an order that upsets lockdep.  Using
4215          * blocking mode is the only way around it.
4216          */
4217 #ifdef CONFIG_DEBUG_LOCK_ALLOC
4218         force_blocking = 1;
4219 #endif
4220
4221         btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4222 again:
4223         level = 1;
4224         next = NULL;
4225         btrfs_release_path(root, path);
4226
4227         path->keep_locks = 1;
4228
4229         if (!force_blocking)
4230                 path->leave_spinning = 1;
4231
4232         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4233         path->keep_locks = 0;
4234
4235         if (ret < 0)
4236                 return ret;
4237
4238         nritems = btrfs_header_nritems(path->nodes[0]);
4239         /*
4240          * by releasing the path above we dropped all our locks.  A balance
4241          * could have added more items next to the key that used to be
4242          * at the very end of the block.  So, check again here and
4243          * advance the path if there are now more items available.
4244          */
4245         if (nritems > 0 && path->slots[0] < nritems - 1) {
4246                 if (ret == 0)
4247                         path->slots[0]++;
4248                 ret = 0;
4249                 goto done;
4250         }
4251
4252         while (level < BTRFS_MAX_LEVEL) {
4253                 if (!path->nodes[level]) {
4254                         ret = 1;
4255                         goto done;
4256                 }
4257
4258                 slot = path->slots[level] + 1;
4259                 c = path->nodes[level];
4260                 if (slot >= btrfs_header_nritems(c)) {
4261                         level++;
4262                         if (level == BTRFS_MAX_LEVEL) {
4263                                 ret = 1;
4264                                 goto done;
4265                         }
4266                         continue;
4267                 }
4268
4269                 if (next) {
4270                         btrfs_tree_unlock(next);
4271                         free_extent_buffer(next);
4272                 }
4273
4274                 next = c;
4275                 ret = read_block_for_search(NULL, root, path, &next, level,
4276                                             slot, &key);
4277                 if (ret == -EAGAIN)
4278                         goto again;
4279
4280                 if (ret < 0) {
4281                         btrfs_release_path(root, path);
4282                         goto done;
4283                 }
4284
4285                 if (!path->skip_locking) {
4286                         ret = btrfs_try_spin_lock(next);
4287                         if (!ret) {
4288                                 btrfs_set_path_blocking(path);
4289                                 btrfs_tree_lock(next);
4290                                 if (!force_blocking)
4291                                         btrfs_clear_path_blocking(path, next);
4292                         }
4293                         if (force_blocking)
4294                                 btrfs_set_lock_blocking(next);
4295                 }
4296                 break;
4297         }
4298         path->slots[level] = slot;
4299         while (1) {
4300                 level--;
4301                 c = path->nodes[level];
4302                 if (path->locks[level])
4303                         btrfs_tree_unlock(c);
4304
4305                 free_extent_buffer(c);
4306                 path->nodes[level] = next;
4307                 path->slots[level] = 0;
4308                 if (!path->skip_locking)
4309                         path->locks[level] = 1;
4310
4311                 if (!level)
4312                         break;
4313
4314                 ret = read_block_for_search(NULL, root, path, &next, level,
4315                                             0, &key);
4316                 if (ret == -EAGAIN)
4317                         goto again;
4318
4319                 if (ret < 0) {
4320                         btrfs_release_path(root, path);
4321                         goto done;
4322                 }
4323
4324                 if (!path->skip_locking) {
4325                         btrfs_assert_tree_locked(path->nodes[level]);
4326                         ret = btrfs_try_spin_lock(next);
4327                         if (!ret) {
4328                                 btrfs_set_path_blocking(path);
4329                                 btrfs_tree_lock(next);
4330                                 if (!force_blocking)
4331                                         btrfs_clear_path_blocking(path, next);
4332                         }
4333                         if (force_blocking)
4334                                 btrfs_set_lock_blocking(next);
4335                 }
4336         }
4337         ret = 0;
4338 done:
4339         unlock_up(path, 0, 1);
4340         path->leave_spinning = old_spinning;
4341         if (!old_spinning)
4342                 btrfs_set_path_blocking(path);
4343
4344         return ret;
4345 }
4346
4347 /*
4348  * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
4349  * searching until it gets past min_objectid or finds an item of 'type'
4350  *
4351  * returns 0 if something is found, 1 if nothing was found and < 0 on error
4352  */
4353 int btrfs_previous_item(struct btrfs_root *root,
4354                         struct btrfs_path *path, u64 min_objectid,
4355                         int type)
4356 {
4357         struct btrfs_key found_key;
4358         struct extent_buffer *leaf;
4359         u32 nritems;
4360         int ret;
4361
4362         while (1) {
4363                 if (path->slots[0] == 0) {
4364                         btrfs_set_path_blocking(path);
4365                         ret = btrfs_prev_leaf(root, path);
4366                         if (ret != 0)
4367                                 return ret;
4368                 } else {
4369                         path->slots[0]--;
4370                 }
4371                 leaf = path->nodes[0];
4372                 nritems = btrfs_header_nritems(leaf);
4373                 if (nritems == 0)
4374                         return 1;
4375                 if (path->slots[0] == nritems)
4376                         path->slots[0]--;
4377
4378                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4379                 if (found_key.objectid < min_objectid)
4380                         break;
4381                 if (found_key.type == type)
4382                         return 0;
4383                 if (found_key.objectid == min_objectid &&
4384                     found_key.type < type)
4385                         break;
4386         }
4387         return 1;
4388 }