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 <linux/slab.h>
  21 #include "ctree.h"
  22 #include "disk-io.h"
  23 #include "transaction.h"
  24 #include "print-tree.h"
  25 #include "locking.h"
  26
  27 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  28                       *root, struct btrfs_path *path, int level);
  29 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  30                       *root, struct btrfs_key *ins_key,
  31                       struct btrfs_path *path, int data_size, int extend);
  32 static int push_node_left(struct btrfs_trans_handle *trans,
  33                           struct btrfs_root *root, struct extent_buffer *dst,
  34                           struct extent_buffer *src, int empty);
  35 static int balance_node_right(struct btrfs_trans_handle *trans,
  36                               struct btrfs_root *root,
  37                               struct extent_buffer *dst_buf,
  38                               struct extent_buffer *src_buf);
  39 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  40                    struct btrfs_path *path, int level, int slot);
  41 static int setup_items_for_insert(struct btrfs_trans_handle *trans,
  42                         struct btrfs_root *root, struct btrfs_path *path,
  43                         struct btrfs_key *cpu_key, u32 *data_size,
  44                         u32 total_data, u32 total_size, int nr);
  45
  46
  47 struct btrfs_path *btrfs_alloc_path(void)
  48 {
  49         struct btrfs_path *path;
  50         path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
  51         if (path)
  52                 path->reada = 1;
  53         return path;
  54 }
  55
  56 /*
  57  * set all locked nodes in the path to blocking locks.  This should
  58  * be done before scheduling
  59  */
  60 noinline void btrfs_set_path_blocking(struct btrfs_path *p)
  61 {
  62         int i;
  63         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  64                 if (p->nodes[i] && p->locks[i])
  65                         btrfs_set_lock_blocking(p->nodes[i]);
  66         }
  67 }
  68
  69 /*
  70  * reset all the locked nodes in the patch to spinning locks.
  71  *
  72  * held is used to keep lockdep happy, when lockdep is enabled
  73  * we set held to a blocking lock before we go around and
  74  * retake all the spinlocks in the path.  You can safely use NULL
  75  * for held
  76  */
  77 noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
  78                                         struct extent_buffer *held)
  79 {
  80         int i;
  81
  82 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  83         /* lockdep really cares that we take all of these spinlocks
  84          * in the right order.  If any of the locks in the path are not
  85          * currently blocking, it is going to complain.  So, make really
  86          * really sure by forcing the path to blocking before we clear
  87          * the path blocking.
  88          */
  89         if (held)
  90                 btrfs_set_lock_blocking(held);
  91         btrfs_set_path_blocking(p);
  92 #endif
  93
  94         for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
  95                 if (p->nodes[i] && p->locks[i])
  96                         btrfs_clear_lock_blocking(p->nodes[i]);
  97         }
  98
  99 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 100         if (held)
 101                 btrfs_clear_lock_blocking(held);
 102 #endif
 103 }
 104
 105 /* this also releases the path */
 106 void btrfs_free_path(struct btrfs_path *p)
 107 {
 108         btrfs_release_path(NULL, p);
 109         kmem_cache_free(btrfs_path_cachep, p);
 110 }
 111
 112 /*
 113  * path release drops references on the extent buffers in the path
 114  * and it drops any locks held by this path
 115  *
 116  * It is safe to call this on paths that no locks or extent buffers held.
 117  */
 118 noinline void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
 119 {
 120         int i;
 121
 122         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
 123                 p->slots[i] = 0;
 124                 if (!p->nodes[i])
 125                         continue;
 126                 if (p->locks[i]) {
 127                         btrfs_tree_unlock(p->nodes[i]);
 128                         p->locks[i] = 0;
 129                 }
 130                 free_extent_buffer(p->nodes[i]);
 131                 p->nodes[i] = NULL;
 132         }
 133 }
 134
 135 /*
 136  * safely gets a reference on the root node of a tree.  A lock
 137  * is not taken, so a concurrent writer may put a different node
 138  * at the root of the tree.  See btrfs_lock_root_node for the
 139  * looping required.
 140  *
 141  * The extent buffer returned by this has a reference taken, so
 142  * it won't disappear.  It may stop being the root of the tree
 143  * at any time because there are no locks held.
 144  */
 145 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
 146 {
 147         struct extent_buffer *eb;
 148         spin_lock(&root->node_lock);
 149         eb = root->node;
 150         extent_buffer_get(eb);
 151         spin_unlock(&root->node_lock);
 152         return eb;
 153 }
 154
 155 /* loop around taking references on and locking the root node of the
 156  * tree until you end up with a lock on the root.  A locked buffer
 157  * is returned, with a reference held.
 158  */
 159 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
 160 {
 161         struct extent_buffer *eb;
 162
 163         while (1) {
 164                 eb = btrfs_root_node(root);
 165                 btrfs_tree_lock(eb);
 166
 167                 spin_lock(&root->node_lock);
 168                 if (eb == root->node) {
 169                         spin_unlock(&root->node_lock);
 170                         break;
 171                 }
 172                 spin_unlock(&root->node_lock);
 173
 174                 btrfs_tree_unlock(eb);
 175                 free_extent_buffer(eb);
 176         }
 177         return eb;
 178 }
 179
 180 /* cowonly root (everything not a reference counted cow subvolume), just get
 181  * put onto a simple dirty list.  transaction.c walks this to make sure they
 182  * get properly updated on disk.
 183  */
 184 static void add_root_to_dirty_list(struct btrfs_root *root)
 185 {
 186         if (root->track_dirty && list_empty(&root->dirty_list)) {
 187                 list_add(&root->dirty_list,
 188                          &root->fs_info->dirty_cowonly_roots);
 189         }
 190 }
 191
 192 /*
 193  * used by snapshot creation to make a copy of a root for a tree with
 194  * a given objectid.  The buffer with the new root node is returned in
 195  * cow_ret, and this func returns zero on success or a negative error code.
 196  */
 197 int btrfs_copy_root(struct btrfs_trans_handle *trans,
 198                       struct btrfs_root *root,
 199                       struct extent_buffer *buf,
 200                       struct extent_buffer **cow_ret, u64 new_root_objectid)
 201 {
 202         struct extent_buffer *cow;
 203         u32 nritems;
 204         int ret = 0;
 205         int level;
 206         struct btrfs_disk_key disk_key;
 207
 208         WARN_ON(root->ref_cows && trans->transid !=
 209                 root->fs_info->running_transaction->transid);
 210         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 211
 212         level = btrfs_header_level(buf);
 213         nritems = btrfs_header_nritems(buf);
 214         if (level == 0)
 215                 btrfs_item_key(buf, &disk_key, 0);
 216         else
 217                 btrfs_node_key(buf, &disk_key, 0);
 218
 219         cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
 220                                      new_root_objectid, &disk_key, level,
 221                                      buf->start, 0);
 222         if (IS_ERR(cow))
 223                 return PTR_ERR(cow);
 224
 225         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 226         btrfs_set_header_bytenr(cow, cow->start);
 227         btrfs_set_header_generation(cow, trans->transid);
 228         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 229         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 230                                      BTRFS_HEADER_FLAG_RELOC);
 231         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 232                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 233         else
 234                 btrfs_set_header_owner(cow, new_root_objectid);
 235
 236         write_extent_buffer(cow, root->fs_info->fsid,
 237                             (unsigned long)btrfs_header_fsid(cow),
 238                             BTRFS_FSID_SIZE);
 239
 240         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 241         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 242                 ret = btrfs_inc_ref(trans, root, cow, 1);
 243         else
 244                 ret = btrfs_inc_ref(trans, root, cow, 0);
 245
 246         if (ret)
 247                 return ret;
 248
 249         btrfs_mark_buffer_dirty(cow);
 250         *cow_ret = cow;
 251         return 0;
 252 }
 253
 254 /*
 255  * check if the tree block can be shared by multiple trees
 256  */
 257 int btrfs_block_can_be_shared(struct btrfs_root *root,
 258                               struct extent_buffer *buf)
 259 {
 260         /*
 261          * Tree blocks not in refernece counted trees and tree roots
 262          * are never shared. If a block was allocated after the last
 263          * snapshot and the block was not allocated by tree relocation,
 264          * we know the block is not shared.
 265          */
 266         if (root->ref_cows &&
 267             buf != root->node && buf != root->commit_root &&
 268             (btrfs_header_generation(buf) <=
 269              btrfs_root_last_snapshot(&root->root_item) ||
 270              btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 271                 return 1;
 272 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 273         if (root->ref_cows &&
 274             btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 275                 return 1;
 276 #endif
 277         return 0;
 278 }
 279
 280 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 281                                        struct btrfs_root *root,
 282                                        struct extent_buffer *buf,
 283                                        struct extent_buffer *cow,
 284                                        int *last_ref)
 285 {
 286         u64 refs;
 287         u64 owner;
 288         u64 flags;
 289         u64 new_flags = 0;
 290         int ret;
 291
 292         /*
 293          * Backrefs update rules:
 294          *
 295          * Always use full backrefs for extent pointers in tree block
 296          * allocated by tree relocation.
 297          *
 298          * If a shared tree block is no longer referenced by its owner
 299          * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 300          * use full backrefs for extent pointers in tree block.
 301          *
 302          * If a tree block is been relocating
 303          * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
 304          * use full backrefs for extent pointers in tree block.
 305          * The reason for this is some operations (such as drop tree)
 306          * are only allowed for blocks use full backrefs.
 307          */
 308
 309         if (btrfs_block_can_be_shared(root, buf)) {
 310                 ret = btrfs_lookup_extent_info(trans, root, buf->start,
 311                                                buf->len, &refs, &flags);
 312                 BUG_ON(ret);
 313                 BUG_ON(refs == 0);
 314         } else {
 315                 refs = 1;
 316                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 317                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 318                         flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
 319                 else
 320                         flags = 0;
 321         }
 322
 323         owner = btrfs_header_owner(buf);
 324         BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
 325                !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
 326
 327         if (refs > 1) {
 328                 if ((owner == root->root_key.objectid ||
 329                      root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 330                     !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 331                         ret = btrfs_inc_ref(trans, root, buf, 1);
 332                         BUG_ON(ret);
 333
 334                         if (root->root_key.objectid ==
 335                             BTRFS_TREE_RELOC_OBJECTID) {
 336                                 ret = btrfs_dec_ref(trans, root, buf, 0);
 337                                 BUG_ON(ret);
 338                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 339                                 BUG_ON(ret);
 340                         }
 341                         new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 342                 } else {
 343
 344                         if (root->root_key.objectid ==
 345                             BTRFS_TREE_RELOC_OBJECTID)
 346                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 347                         else
 348                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 349                         BUG_ON(ret);
 350                 }
 351                 if (new_flags != 0) {
 352                         ret = btrfs_set_disk_extent_flags(trans, root,
 353                                                           buf->start,
 354                                                           buf->len,
 355                                                           new_flags, 0);
 356                         BUG_ON(ret);
 357                 }
 358         } else {
 359                 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
 360                         if (root->root_key.objectid ==
 361                             BTRFS_TREE_RELOC_OBJECTID)
 362                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 363                         else
 364                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 365                         BUG_ON(ret);
 366                         ret = btrfs_dec_ref(trans, root, buf, 1);
 367                         BUG_ON(ret);
 368                 }
 369                 clean_tree_block(trans, root, buf);
 370                 *last_ref = 1;
 371         }
 372         return 0;
 373 }
 374
 375 /*
 376  * does the dirty work in cow of a single block.  The parent block (if
 377  * supplied) is updated to point to the new cow copy.  The new buffer is marked
 378  * dirty and returned locked.  If you modify the block it needs to be marked
 379  * dirty again.
 380  *
 381  * search_start -- an allocation hint for the new block
 382  *
 383  * empty_size -- a hint that you plan on doing more cow.  This is the size in
 384  * bytes the allocator should try to find free next to the block it returns.
 385  * This is just a hint and may be ignored by the allocator.
 386  */
 387 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 388                              struct btrfs_root *root,
 389                              struct extent_buffer *buf,
 390                              struct extent_buffer *parent, int parent_slot,
 391                              struct extent_buffer **cow_ret,
 392                              u64 search_start, u64 empty_size)
 393 {
 394         struct btrfs_disk_key disk_key;
 395         struct extent_buffer *cow;
 396         int level;
 397         int last_ref = 0;
 398         int unlock_orig = 0;
 399         u64 parent_start;
 400
 401         if (*cow_ret == buf)
 402                 unlock_orig = 1;
 403
 404         btrfs_assert_tree_locked(buf);
 405
 406         WARN_ON(root->ref_cows && trans->transid !=
 407                 root->fs_info->running_transaction->transid);
 408         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 409
 410         level = btrfs_header_level(buf);
 411
 412         if (level == 0)
 413                 btrfs_item_key(buf, &disk_key, 0);
 414         else
 415                 btrfs_node_key(buf, &disk_key, 0);
 416
 417         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
 418                 if (parent)
 419                         parent_start = parent->start;
 420                 else
 421                         parent_start = 0;
 422         } else
 423                 parent_start = 0;
 424
 425         cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
 426                                      root->root_key.objectid, &disk_key,
 427                                      level, search_start, empty_size);
 428         if (IS_ERR(cow))
 429                 return PTR_ERR(cow);
 430
 431         /* cow is set to blocking by btrfs_init_new_buffer */
 432
 433         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 434         btrfs_set_header_bytenr(cow, cow->start);
 435         btrfs_set_header_generation(cow, trans->transid);
 436         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 437         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 438                                      BTRFS_HEADER_FLAG_RELOC);
 439         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 440                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 441         else
 442                 btrfs_set_header_owner(cow, root->root_key.objectid);
 443
 444         write_extent_buffer(cow, root->fs_info->fsid,
 445                             (unsigned long)btrfs_header_fsid(cow),
 446                             BTRFS_FSID_SIZE);
 447
 448         update_ref_for_cow(trans, root, buf, cow, &last_ref);
 449
 450         if (root->ref_cows)
 451                 btrfs_reloc_cow_block(trans, root, buf, cow);
 452
 453         if (buf == root->node) {
 454                 WARN_ON(parent && parent != buf);
 455                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 456                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 457                         parent_start = buf->start;
 458                 else
 459                         parent_start = 0;
 460
 461                 spin_lock(&root->node_lock);
 462                 root->node = cow;
 463                 extent_buffer_get(cow);
 464                 spin_unlock(&root->node_lock);
 465
 466                 btrfs_free_tree_block(trans, root, buf, parent_start,
 467                                       last_ref);
 468                 free_extent_buffer(buf);
 469                 add_root_to_dirty_list(root);
 470         } else {
 471                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 472                         parent_start = parent->start;
 473                 else
 474                         parent_start = 0;
 475
 476                 WARN_ON(trans->transid != btrfs_header_generation(parent));
 477                 btrfs_set_node_blockptr(parent, parent_slot,
 478                                         cow->start);
 479                 btrfs_set_node_ptr_generation(parent, parent_slot,
 480                                               trans->transid);
 481                 btrfs_mark_buffer_dirty(parent);
 482                 btrfs_free_tree_block(trans, root, buf, parent_start,
 483                                       last_ref);
 484         }
 485         if (unlock_orig)
 486                 btrfs_tree_unlock(buf);
 487         free_extent_buffer(buf);
 488         btrfs_mark_buffer_dirty(cow);
 489         *cow_ret = cow;
 490         return 0;
 491 }
 492
 493 static inline int should_cow_block(struct btrfs_trans_handle *trans,
 494                                    struct btrfs_root *root,
 495                                    struct extent_buffer *buf)
 496 {
 497         if (btrfs_header_generation(buf) == trans->transid &&
 498             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
 499             !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
 500               btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 501                 return 0;
 502         return 1;
 503 }
 504
 505 /*
 506  * cows a single block, see __btrfs_cow_block for the real work.
 507  * This version of it has extra checks so that a block isn't cow'd more than
 508  * once per transaction, as long as it hasn't been written yet
 509  */
 510 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
 511                     struct btrfs_root *root, struct extent_buffer *buf,
 512                     struct extent_buffer *parent, int parent_slot,
 513                     struct extent_buffer **cow_ret)
 514 {
 515         u64 search_start;
 516         int ret;
 517
 518         if (trans->transaction != root->fs_info->running_transaction) {
 519                 printk(KERN_CRIT "trans %llu running %llu\n",
 520                        (unsigned long long)trans->transid,
 521                        (unsigned long long)
 522                        root->fs_info->running_transaction->transid);
 523                 WARN_ON(1);
 524         }
 525         if (trans->transid != root->fs_info->generation) {
 526                 printk(KERN_CRIT "trans %llu running %llu\n",
 527                        (unsigned long long)trans->transid,
 528                        (unsigned long long)root->fs_info->generation);
 529                 WARN_ON(1);
 530         }
 531
 532         if (!should_cow_block(trans, root, buf)) {
 533                 *cow_ret = buf;
 534                 return 0;
 535         }
 536
 537         search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
 538
 539         if (parent)
 540                 btrfs_set_lock_blocking(parent);
 541         btrfs_set_lock_blocking(buf);
 542
 543         ret = __btrfs_cow_block(trans, root, buf, parent,
 544                                  parent_slot, cow_ret, search_start, 0);
 545         return ret;
 546 }
 547
 548 /*
 549  * helper function for defrag to decide if two blocks pointed to by a
 550  * node are actually close by
 551  */
 552 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 553 {
 554         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 555                 return 1;
 556         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 557                 return 1;
 558         return 0;
 559 }
 560
 561 /*
 562  * compare two keys in a memcmp fashion
 563  */
 564 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 565 {
 566         struct btrfs_key k1;
 567
 568         btrfs_disk_key_to_cpu(&k1, disk);
 569
 570         return btrfs_comp_cpu_keys(&k1, k2);
 571 }
 572
 573 /*
 574  * same as comp_keys only with two btrfs_key's
 575  */
 576 int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
 577 {
 578         if (k1->objectid > k2->objectid)
 579                 return 1;
 580         if (k1->objectid < k2->objectid)
 581                 return -1;
 582         if (k1->type > k2->type)
 583                 return 1;
 584         if (k1->type < k2->type)
 585                 return -1;
 586         if (k1->offset > k2->offset)
 587                 return 1;
 588         if (k1->offset < k2->offset)
 589                 return -1;
 590         return 0;
 591 }
 592
 593 /*
 594  * this is used by the defrag code to go through all the
 595  * leaves pointed to by a node and reallocate them so that
 596  * disk order is close to key order
 597  */
 598 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 599                        struct btrfs_root *root, struct extent_buffer *parent,
 600                        int start_slot, int cache_only, u64 *last_ret,
 601                        struct btrfs_key *progress)
 602 {
 603         struct extent_buffer *cur;
 604         u64 blocknr;
 605         u64 gen;
 606         u64 search_start = *last_ret;
 607         u64 last_block = 0;
 608         u64 other;
 609         u32 parent_nritems;
 610         int end_slot;
 611         int i;
 612         int err = 0;
 613         int parent_level;
 614         int uptodate;
 615         u32 blocksize;
 616         int progress_passed = 0;
 617         struct btrfs_disk_key disk_key;
 618
 619         parent_level = btrfs_header_level(parent);
 620         if (cache_only && parent_level != 1)
 621                 return 0;
 622
 623         if (trans->transaction != root->fs_info->running_transaction)
 624                 WARN_ON(1);
 625         if (trans->transid != root->fs_info->generation)
 626                 WARN_ON(1);
 627
 628         parent_nritems = btrfs_header_nritems(parent);
 629         blocksize = btrfs_level_size(root, parent_level - 1);
 630         end_slot = parent_nritems;
 631
 632         if (parent_nritems == 1)
 633                 return 0;
 634
 635         btrfs_set_lock_blocking(parent);
 636
 637         for (i = start_slot; i < end_slot; i++) {
 638                 int close = 1;
 639
 640                 if (!parent->map_token) {
 641                         map_extent_buffer(parent,
 642                                         btrfs_node_key_ptr_offset(i),
 643                                         sizeof(struct btrfs_key_ptr),
 644                                         &parent->map_token, &parent->kaddr,
 645                                         &parent->map_start, &parent->map_len,
 646                                         KM_USER1);
 647                 }
 648                 btrfs_node_key(parent, &disk_key, i);
 649                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
 650                         continue;
 651
 652                 progress_passed = 1;
 653                 blocknr = btrfs_node_blockptr(parent, i);
 654                 gen = btrfs_node_ptr_generation(parent, i);
 655                 if (last_block == 0)
 656                         last_block = blocknr;
 657
 658                 if (i > 0) {
 659                         other = btrfs_node_blockptr(parent, i - 1);
 660                         close = close_blocks(blocknr, other, blocksize);
 661                 }
 662                 if (!close && i < end_slot - 2) {
 663                         other = btrfs_node_blockptr(parent, i + 1);
 664                         close = close_blocks(blocknr, other, blocksize);
 665                 }
 666                 if (close) {
 667                         last_block = blocknr;
 668                         continue;
 669                 }
 670                 if (parent->map_token) {
 671                         unmap_extent_buffer(parent, parent->map_token,
 672                                             KM_USER1);
 673                         parent->map_token = NULL;
 674                 }
 675
 676                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
 677                 if (cur)
 678                         uptodate = btrfs_buffer_uptodate(cur, gen);
 679                 else
 680                         uptodate = 0;
 681                 if (!cur || !uptodate) {
 682                         if (cache_only) {
 683                                 free_extent_buffer(cur);
 684                                 continue;
 685                         }
 686                         if (!cur) {
 687                                 cur = read_tree_block(root, blocknr,
 688                                                          blocksize, gen);
 689                         } else if (!uptodate) {
 690                                 btrfs_read_buffer(cur, gen);
 691                         }
 692                 }
 693                 if (search_start == 0)
 694                         search_start = last_block;
 695
 696                 btrfs_tree_lock(cur);
 697                 btrfs_set_lock_blocking(cur);
 698                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 699                                         &cur, search_start,
 700                                         min(16 * blocksize,
 701                                             (end_slot - i) * blocksize));
 702                 if (err) {
 703                         btrfs_tree_unlock(cur);
 704                         free_extent_buffer(cur);
 705                         break;
 706                 }
 707                 search_start = cur->start;
 708                 last_block = cur->start;
 709                 *last_ret = search_start;
 710                 btrfs_tree_unlock(cur);
 711                 free_extent_buffer(cur);
 712         }
 713         if (parent->map_token) {
 714                 unmap_extent_buffer(parent, parent->map_token,
 715                                     KM_USER1);
 716                 parent->map_token = NULL;
 717         }
 718         return err;
 719 }
 720
 721 /*
 722  * The leaf data grows from end-to-front in the node.
 723  * this returns the address of the start of the last item,
 724  * which is the stop of the leaf data stack
 725  */
 726 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 727                                          struct extent_buffer *leaf)
 728 {
 729         u32 nr = btrfs_header_nritems(leaf);
 730         if (nr == 0)
 731                 return BTRFS_LEAF_DATA_SIZE(root);
 732         return btrfs_item_offset_nr(leaf, nr - 1);
 733 }
 734
 735 /*
 736  * extra debugging checks to make sure all the items in a key are
 737  * well formed and in the proper order
 738  */
 739 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 740                       int level)
 741 {
 742         struct extent_buffer *parent = NULL;
 743         struct extent_buffer *node = path->nodes[level];
 744         struct btrfs_disk_key parent_key;
 745         struct btrfs_disk_key node_key;
 746         int parent_slot;
 747         int slot;
 748         struct btrfs_key cpukey;
 749         u32 nritems = btrfs_header_nritems(node);
 750
 751         if (path->nodes[level + 1])
 752                 parent = path->nodes[level + 1];
 753
 754         slot = path->slots[level];
 755         BUG_ON(nritems == 0);
 756         if (parent) {
 757                 parent_slot = path->slots[level + 1];
 758                 btrfs_node_key(parent, &parent_key, parent_slot);
 759                 btrfs_node_key(node, &node_key, 0);
 760                 BUG_ON(memcmp(&parent_key, &node_key,
 761                               sizeof(struct btrfs_disk_key)));
 762                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 763                        btrfs_header_bytenr(node));
 764         }
 765         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 766         if (slot != 0) {
 767                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 768                 btrfs_node_key(node, &node_key, slot);
 769                 BUG_ON(comp_keys(&node_key, &cpukey) <= 0);
 770         }
 771         if (slot < nritems - 1) {
 772                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 773                 btrfs_node_key(node, &node_key, slot);
 774                 BUG_ON(comp_keys(&node_key, &cpukey) >= 0);
 775         }
 776         return 0;
 777 }
 778
 779 /*
 780  * extra checking to make sure all the items in a leaf are
 781  * well formed and in the proper order
 782  */
 783 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 784                       int level)
 785 {
 786         struct extent_buffer *leaf = path->nodes[level];
 787         struct extent_buffer *parent = NULL;
 788         int parent_slot;
 789         struct btrfs_key cpukey;
 790         struct btrfs_disk_key parent_key;
 791         struct btrfs_disk_key leaf_key;
 792         int slot = path->slots[0];
 793
 794         u32 nritems = btrfs_header_nritems(leaf);
 795
 796         if (path->nodes[level + 1])
 797                 parent = path->nodes[level + 1];
 798
 799         if (nritems == 0)
 800                 return 0;
 801
 802         if (parent) {
 803                 parent_slot = path->slots[level + 1];
 804                 btrfs_node_key(parent, &parent_key, parent_slot);
 805                 btrfs_item_key(leaf, &leaf_key, 0);
 806
 807                 BUG_ON(memcmp(&parent_key, &leaf_key,
 808                        sizeof(struct btrfs_disk_key)));
 809                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 810                        btrfs_header_bytenr(leaf));
 811         }
 812         if (slot != 0 && slot < nritems - 1) {
 813                 btrfs_item_key(leaf, &leaf_key, slot);
 814                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 815                 if (comp_keys(&leaf_key, &cpukey) <= 0) {
 816                         btrfs_print_leaf(root, leaf);
 817                         printk(KERN_CRIT "slot %d offset bad key\n", slot);
 818                         BUG_ON(1);
 819                 }
 820                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 821                        btrfs_item_end_nr(leaf, slot)) {
 822                         btrfs_print_leaf(root, leaf);
 823                         printk(KERN_CRIT "slot %d offset bad\n", slot);
 824                         BUG_ON(1);
 825                 }
 826         }
 827         if (slot < nritems - 1) {
 828                 btrfs_item_key(leaf, &leaf_key, slot);
 829                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 830                 BUG_ON(comp_keys(&leaf_key, &cpukey) >= 0);
 831                 if (btrfs_item_offset_nr(leaf, slot) !=
 832                         btrfs_item_end_nr(leaf, slot + 1)) {
 833                         btrfs_print_leaf(root, leaf);
 834                         printk(KERN_CRIT "slot %d offset bad\n", slot);
 835                         BUG_ON(1);
 836                 }
 837         }
 838         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 839                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 840         return 0;
 841 }
 842
 843 static noinline int check_block(struct btrfs_root *root,
 844                                 struct btrfs_path *path, int level)
 845 {
 846         return 0;
 847         if (level == 0)
 848                 return check_leaf(root, path, level);
 849         return check_node(root, path, level);
 850 }
 851
 852 /*
 853  * search for key in the extent_buffer.  The items start at offset p,
 854  * and they are item_size apart.  There are 'max' items in p.
 855  *
 856  * the slot in the array is returned via slot, and it points to
 857  * the place where you would insert key if it is not found in
 858  * the array.
 859  *
 860  * slot may point to max if the key is bigger than all of the keys
 861  */
 862 static noinline int generic_bin_search(struct extent_buffer *eb,
 863                                        unsigned long p,
 864                                        int item_size, struct btrfs_key *key,
 865                                        int max, int *slot)
 866 {
 867         int low = 0;
 868         int high = max;
 869         int mid;
 870         int ret;
 871         struct btrfs_disk_key *tmp = NULL;
 872         struct btrfs_disk_key unaligned;
 873         unsigned long offset;
 874         char *map_token = NULL;
 875         char *kaddr = NULL;
 876         unsigned long map_start = 0;
 877         unsigned long map_len = 0;
 878         int err;
 879
 880         while (low < high) {
 881                 mid = (low + high) / 2;
 882                 offset = p + mid * item_size;
 883
 884                 if (!map_token || offset < map_start ||
 885                     (offset + sizeof(struct btrfs_disk_key)) >
 886                     map_start + map_len) {
 887                         if (map_token) {
 888                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 889                                 map_token = NULL;
 890                         }
 891
 892                         err = map_private_extent_buffer(eb, offset,
 893                                                 sizeof(struct btrfs_disk_key),
 894                                                 &map_token, &kaddr,
 895                                                 &map_start, &map_len, KM_USER0);
 896
 897                         if (!err) {
 898                                 tmp = (struct btrfs_disk_key *)(kaddr + offset -
 899                                                         map_start);
 900                         } else {
 901                                 read_extent_buffer(eb, &unaligned,
 902                                                    offset, sizeof(unaligned));
 903                                 tmp = &unaligned;
 904                         }
 905
 906                 } else {
 907                         tmp = (struct btrfs_disk_key *)(kaddr + offset -
 908                                                         map_start);
 909                 }
 910                 ret = comp_keys(tmp, key);
 911
 912                 if (ret < 0)
 913                         low = mid + 1;
 914                 else if (ret > 0)
 915                         high = mid;
 916                 else {
 917                         *slot = mid;
 918                         if (map_token)
 919                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 920                         return 0;
 921                 }
 922         }
 923         *slot = low;
 924         if (map_token)
 925                 unmap_extent_buffer(eb, map_token, KM_USER0);
 926         return 1;
 927 }
 928
 929 /*
 930  * simple bin_search frontend that does the right thing for
 931  * leaves vs nodes
 932  */
 933 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 934                       int level, int *slot)
 935 {
 936         if (level == 0) {
 937                 return generic_bin_search(eb,
 938                                           offsetof(struct btrfs_leaf, items),
 939                                           sizeof(struct btrfs_item),
 940                                           key, btrfs_header_nritems(eb),
 941                                           slot);
 942         } else {
 943                 return generic_bin_search(eb,
 944                                           offsetof(struct btrfs_node, ptrs),
 945                                           sizeof(struct btrfs_key_ptr),
 946                                           key, btrfs_header_nritems(eb),
 947                                           slot);
 948         }
 949         return -1;
 950 }
 951
 952 int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 953                      int level, int *slot)
 954 {
 955         return bin_search(eb, key, level, slot);
 956 }
 957
 958 static void root_add_used(struct btrfs_root *root, u32 size)
 959 {
 960         spin_lock(&root->accounting_lock);
 961         btrfs_set_root_used(&root->root_item,
 962                             btrfs_root_used(&root->root_item) + size);
 963         spin_unlock(&root->accounting_lock);
 964 }
 965
 966 static void root_sub_used(struct btrfs_root *root, u32 size)
 967 {
 968         spin_lock(&root->accounting_lock);
 969         btrfs_set_root_used(&root->root_item,
 970                             btrfs_root_used(&root->root_item) - size);
 971         spin_unlock(&root->accounting_lock);
 972 }
 973
 974 /* given a node and slot number, this reads the blocks it points to.  The
 975  * extent buffer is returned with a reference taken (but unlocked).
 976  * NULL is returned on error.
 977  */
 978 static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
 979                                    struct extent_buffer *parent, int slot)
 980 {
 981         int level = btrfs_header_level(parent);
 982         if (slot < 0)
 983                 return NULL;
 984         if (slot >= btrfs_header_nritems(parent))
 985                 return NULL;
 986
 987         BUG_ON(level == 0);
 988
 989         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 990                        btrfs_level_size(root, level - 1),
 991                        btrfs_node_ptr_generation(parent, slot));
 992 }
 993
 994 /*
 995  * node level balancing, used to make sure nodes are in proper order for
 996  * item deletion.  We balance from the top down, so we have to make sure
 997  * that a deletion won't leave an node completely empty later on.
 998  */
 999 static noinline int balance_level(struct btrfs_trans_handle *trans,
1000                          struct btrfs_root *root,
1001                          struct btrfs_path *path, int level)
1002 {
1003         struct extent_buffer *right = NULL;
1004         struct extent_buffer *mid;
1005         struct extent_buffer *left = NULL;
1006         struct extent_buffer *parent = NULL;
1007         int ret = 0;
1008         int wret;
1009         int pslot;
1010         int orig_slot = path->slots[level];
1011         int err_on_enospc = 0;
1012         u64 orig_ptr;
1013
1014         if (level == 0)
1015                 return 0;
1016
1017         mid = path->nodes[level];
1018
1019         WARN_ON(!path->locks[level]);
1020         WARN_ON(btrfs_header_generation(mid) != trans->transid);
1021
1022         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1023
1024         if (level < BTRFS_MAX_LEVEL - 1)
1025                 parent = path->nodes[level + 1];
1026         pslot = path->slots[level + 1];
1027
1028         /*
1029          * deal with the case where there is only one pointer in the root
1030          * by promoting the node below to a root
1031          */
1032         if (!parent) {
1033                 struct extent_buffer *child;
1034
1035                 if (btrfs_header_nritems(mid) != 1)
1036                         return 0;
1037
1038                 /* promote the child to a root */
1039                 child = read_node_slot(root, mid, 0);
1040                 BUG_ON(!child);
1041                 btrfs_tree_lock(child);
1042                 btrfs_set_lock_blocking(child);
1043                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1044                 if (ret) {
1045                         btrfs_tree_unlock(child);
1046                         free_extent_buffer(child);
1047                         goto enospc;
1048                 }
1049
1050                 spin_lock(&root->node_lock);
1051                 root->node = child;
1052                 spin_unlock(&root->node_lock);
1053
1054                 add_root_to_dirty_list(root);
1055                 btrfs_tree_unlock(child);
1056
1057                 path->locks[level] = 0;
1058                 path->nodes[level] = NULL;
1059                 clean_tree_block(trans, root, mid);
1060                 btrfs_tree_unlock(mid);
1061                 /* once for the path */
1062                 free_extent_buffer(mid);
1063
1064                 root_sub_used(root, mid->len);
1065                 btrfs_free_tree_block(trans, root, mid, 0, 1);
1066                 /* once for the root ptr */
1067                 free_extent_buffer(mid);
1068                 return 0;
1069         }
1070         if (btrfs_header_nritems(mid) >
1071             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
1072                 return 0;
1073
1074         if (btrfs_header_nritems(mid) < 2)
1075                 err_on_enospc = 1;
1076
1077         left = read_node_slot(root, parent, pslot - 1);
1078         if (left) {
1079                 btrfs_tree_lock(left);
1080                 btrfs_set_lock_blocking(left);
1081                 wret = btrfs_cow_block(trans, root, left,
1082                                        parent, pslot - 1, &left);
1083                 if (wret) {
1084                         ret = wret;
1085                         goto enospc;
1086                 }
1087         }
1088         right = read_node_slot(root, parent, pslot + 1);
1089         if (right) {
1090                 btrfs_tree_lock(right);
1091                 btrfs_set_lock_blocking(right);
1092                 wret = btrfs_cow_block(trans, root, right,
1093                                        parent, pslot + 1, &right);
1094                 if (wret) {
1095                         ret = wret;
1096                         goto enospc;
1097                 }
1098         }
1099
1100         /* first, try to make some room in the middle buffer */
1101         if (left) {
1102                 orig_slot += btrfs_header_nritems(left);
1103                 wret = push_node_left(trans, root, left, mid, 1);
1104                 if (wret < 0)
1105                         ret = wret;
1106                 if (btrfs_header_nritems(mid) < 2)
1107                         err_on_enospc = 1;
1108         }
1109
1110         /*
1111          * then try to empty the right most buffer into the middle
1112          */
1113         if (right) {
1114                 wret = push_node_left(trans, root, mid, right, 1);
1115                 if (wret < 0 && wret != -ENOSPC)
1116                         ret = wret;
1117                 if (btrfs_header_nritems(right) == 0) {
1118                         clean_tree_block(trans, root, right);
1119                         btrfs_tree_unlock(right);
1120                         wret = del_ptr(trans, root, path, level + 1, pslot +
1121                                        1);
1122                         if (wret)
1123                                 ret = wret;
1124                         root_sub_used(root, right->len);
1125                         btrfs_free_tree_block(trans, root, right, 0, 1);
1126                         free_extent_buffer(right);
1127                         right = NULL;
1128                 } else {
1129                         struct btrfs_disk_key right_key;
1130                         btrfs_node_key(right, &right_key, 0);
1131                         btrfs_set_node_key(parent, &right_key, pslot + 1);
1132                         btrfs_mark_buffer_dirty(parent);
1133                 }
1134         }
1135         if (btrfs_header_nritems(mid) == 1) {
1136                 /*
1137                  * we're not allowed to leave a node with one item in the
1138                  * tree during a delete.  A deletion from lower in the tree
1139                  * could try to delete the only pointer in this node.
1140                  * So, pull some keys from the left.
1141                  * There has to be a left pointer at this point because
1142                  * otherwise we would have pulled some pointers from the
1143                  * right
1144                  */
1145                 BUG_ON(!left);
1146                 wret = balance_node_right(trans, root, mid, left);
1147                 if (wret < 0) {
1148                         ret = wret;
1149                         goto enospc;
1150                 }
1151                 if (wret == 1) {
1152                         wret = push_node_left(trans, root, left, mid, 1);
1153                         if (wret < 0)
1154                                 ret = wret;
1155                 }
1156                 BUG_ON(wret == 1);
1157         }
1158         if (btrfs_header_nritems(mid) == 0) {
1159                 clean_tree_block(trans, root, mid);
1160                 btrfs_tree_unlock(mid);
1161                 wret = del_ptr(trans, root, path, level + 1, pslot);
1162                 if (wret)
1163                         ret = wret;
1164                 root_sub_used(root, mid->len);
1165                 btrfs_free_tree_block(trans, root, mid, 0, 1);
1166                 free_extent_buffer(mid);
1167                 mid = NULL;
1168         } else {
1169                 /* update the parent key to reflect our changes */
1170                 struct btrfs_disk_key mid_key;
1171                 btrfs_node_key(mid, &mid_key, 0);
1172                 btrfs_set_node_key(parent, &mid_key, pslot);
1173                 btrfs_mark_buffer_dirty(parent);
1174         }
1175
1176         /* update the path */
1177         if (left) {
1178                 if (btrfs_header_nritems(left) > orig_slot) {
1179                         extent_buffer_get(left);
1180                         /* left was locked after cow */
1181                         path->nodes[level] = left;
1182                         path->slots[level + 1] -= 1;
1183                         path->slots[level] = orig_slot;
1184                         if (mid) {
1185                                 btrfs_tree_unlock(mid);
1186                                 free_extent_buffer(mid);
1187                         }
1188                 } else {
1189                         orig_slot -= btrfs_header_nritems(left);
1190                         path->slots[level] = orig_slot;
1191                 }
1192         }
1193         /* double check we haven't messed things up */
1194         check_block(root, path, level);
1195         if (orig_ptr !=
1196             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1197                 BUG();
1198 enospc:
1199         if (right) {
1200                 btrfs_tree_unlock(right);
1201                 free_extent_buffer(right);
1202         }
1203         if (left) {
1204                 if (path->nodes[level] != left)
1205                         btrfs_tree_unlock(left);
1206                 free_extent_buffer(left);
1207         }
1208         return ret;
1209 }
1210
1211 /* Node balancing for insertion.  Here we only split or push nodes around
1212  * when they are completely full.  This is also done top down, so we
1213  * have to be pessimistic.
1214  */
1215 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1216                                           struct btrfs_root *root,
1217                                           struct btrfs_path *path, int level)
1218 {
1219         struct extent_buffer *right = NULL;
1220         struct extent_buffer *mid;
1221         struct extent_buffer *left = NULL;
1222         struct extent_buffer *parent = NULL;
1223         int ret = 0;
1224         int wret;
1225         int pslot;
1226         int orig_slot = path->slots[level];
1227         u64 orig_ptr;
1228
1229         if (level == 0)
1230                 return 1;
1231
1232         mid = path->nodes[level];
1233         WARN_ON(btrfs_header_generation(mid) != trans->transid);
1234         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1235
1236         if (level < BTRFS_MAX_LEVEL - 1)
1237                 parent = path->nodes[level + 1];
1238         pslot = path->slots[level + 1];
1239
1240         if (!parent)
1241                 return 1;
1242
1243         left = read_node_slot(root, parent, pslot - 1);
1244
1245         /* first, try to make some room in the middle buffer */
1246         if (left) {
1247                 u32 left_nr;
1248
1249                 btrfs_tree_lock(left);
1250                 btrfs_set_lock_blocking(left);
1251
1252                 left_nr = btrfs_header_nritems(left);
1253                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1254                         wret = 1;
1255                 } else {
1256                         ret = btrfs_cow_block(trans, root, left, parent,
1257                                               pslot - 1, &left);
1258                         if (ret)
1259                                 wret = 1;
1260                         else {
1261                                 wret = push_node_left(trans, root,
1262                                                       left, mid, 0);
1263                         }
1264                 }
1265                 if (wret < 0)
1266                         ret = wret;
1267                 if (wret == 0) {
1268                         struct btrfs_disk_key disk_key;
1269                         orig_slot += left_nr;
1270                         btrfs_node_key(mid, &disk_key, 0);
1271                         btrfs_set_node_key(parent, &disk_key, pslot);
1272                         btrfs_mark_buffer_dirty(parent);
1273                         if (btrfs_header_nritems(left) > orig_slot) {
1274                                 path->nodes[level] = left;
1275                                 path->slots[level + 1] -= 1;
1276                                 path->slots[level] = orig_slot;
1277                                 btrfs_tree_unlock(mid);
1278                                 free_extent_buffer(mid);
1279                         } else {
1280                                 orig_slot -=
1281                                         btrfs_header_nritems(left);
1282                                 path->slots[level] = orig_slot;
1283                                 btrfs_tree_unlock(left);
1284                                 free_extent_buffer(left);
1285                         }
1286                         return 0;
1287                 }
1288                 btrfs_tree_unlock(left);
1289                 free_extent_buffer(left);
1290         }
1291         right = read_node_slot(root, parent, pslot + 1);
1292
1293         /*
1294          * then try to empty the right most buffer into the middle
1295          */
1296         if (right) {
1297                 u32 right_nr;
1298
1299                 btrfs_tree_lock(right);
1300                 btrfs_set_lock_blocking(right);
1301
1302                 right_nr = btrfs_header_nritems(right);
1303                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1304                         wret = 1;
1305                 } else {
1306                         ret = btrfs_cow_block(trans, root, right,
1307                                               parent, pslot + 1,
1308                                               &right);
1309                         if (ret)
1310                                 wret = 1;
1311                         else {
1312                                 wret = balance_node_right(trans, root,
1313                                                           right, mid);
1314                         }
1315                 }
1316                 if (wret < 0)
1317                         ret = wret;
1318                 if (wret == 0) {
1319                         struct btrfs_disk_key disk_key;
1320
1321                         btrfs_node_key(right, &disk_key, 0);
1322                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
1323                         btrfs_mark_buffer_dirty(parent);
1324
1325                         if (btrfs_header_nritems(mid) <= orig_slot) {
1326                                 path->nodes[level] = right;
1327                                 path->slots[level + 1] += 1;
1328                                 path->slots[level] = orig_slot -
1329                                         btrfs_header_nritems(mid);
1330                                 btrfs_tree_unlock(mid);
1331                                 free_extent_buffer(mid);
1332                         } else {
1333                                 btrfs_tree_unlock(right);
1334                                 free_extent_buffer(right);
1335                         }
1336                         return 0;
1337                 }
1338                 btrfs_tree_unlock(right);
1339                 free_extent_buffer(right);
1340         }
1341         return 1;
1342 }
1343
1344 /*
1345  * readahead one full node of leaves, finding things that are close
1346  * to the block in 'slot', and triggering ra on them.
1347  */
1348 static void reada_for_search(struct btrfs_root *root,
1349                              struct btrfs_path *path,
1350                              int level, int slot, u64 objectid)
1351 {
1352         struct extent_buffer *node;
1353         struct btrfs_disk_key disk_key;
1354         u32 nritems;
1355         u64 search;
1356         u64 target;
1357         u64 nread = 0;
1358         int direction = path->reada;
1359         struct extent_buffer *eb;
1360         u32 nr;
1361         u32 blocksize;
1362         u32 nscan = 0;
1363
1364         if (level != 1)
1365                 return;
1366
1367         if (!path->nodes[level])
1368                 return;
1369
1370         node = path->nodes[level];
1371
1372         search = btrfs_node_blockptr(node, slot);
1373         blocksize = btrfs_level_size(root, level - 1);
1374         eb = btrfs_find_tree_block(root, search, blocksize);
1375         if (eb) {
1376                 free_extent_buffer(eb);
1377                 return;
1378         }
1379
1380         target = search;
1381
1382         nritems = btrfs_header_nritems(node);
1383         nr = slot;
1384         while (1) {
1385                 if (direction < 0) {
1386                         if (nr == 0)
1387                                 break;
1388                         nr--;
1389                 } else if (direction > 0) {
1390                         nr++;
1391                         if (nr >= nritems)
1392                                 break;
1393                 }
1394                 if (path->reada < 0 && objectid) {
1395                         btrfs_node_key(node, &disk_key, nr);
1396                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1397                                 break;
1398                 }
1399                 search = btrfs_node_blockptr(node, nr);
1400                 if ((search <= target && target - search <= 65536) ||
1401                     (search > target && search - target <= 65536)) {
1402                         readahead_tree_block(root, search, blocksize,
1403                                      btrfs_node_ptr_generation(node, nr));
1404                         nread += blocksize;
1405                 }
1406                 nscan++;
1407                 if ((nread > 65536 || nscan > 32))
1408                         break;
1409         }
1410 }
1411
1412 /*
1413  * returns -EAGAIN if it had to drop the path, or zero if everything was in
1414  * cache
1415  */
1416 static noinline int reada_for_balance(struct btrfs_root *root,
1417                                       struct btrfs_path *path, int level)
1418 {
1419         int slot;
1420         int nritems;
1421         struct extent_buffer *parent;
1422         struct extent_buffer *eb;
1423         u64 gen;
1424         u64 block1 = 0;
1425         u64 block2 = 0;
1426         int ret = 0;
1427         int blocksize;
1428
1429         parent = path->nodes[level + 1];
1430         if (!parent)
1431                 return 0;
1432
1433         nritems = btrfs_header_nritems(parent);
1434         slot = path->slots[level + 1];
1435         blocksize = btrfs_level_size(root, level);
1436
1437         if (slot > 0) {
1438                 block1 = btrfs_node_blockptr(parent, slot - 1);
1439                 gen = btrfs_node_ptr_generation(parent, slot - 1);
1440                 eb = btrfs_find_tree_block(root, block1, blocksize);
1441                 if (eb && btrfs_buffer_uptodate(eb, gen))
1442                         block1 = 0;
1443                 free_extent_buffer(eb);
1444         }
1445         if (slot + 1 < nritems) {
1446                 block2 = btrfs_node_blockptr(parent, slot + 1);
1447                 gen = btrfs_node_ptr_generation(parent, slot + 1);
1448                 eb = btrfs_find_tree_block(root, block2, blocksize);
1449                 if (eb && btrfs_buffer_uptodate(eb, gen))
1450                         block2 = 0;
1451                 free_extent_buffer(eb);
1452         }
1453         if (block1 || block2) {
1454                 ret = -EAGAIN;
1455
1456                 /* release the whole path */
1457                 btrfs_release_path(root, path);
1458
1459                 /* read the blocks */
1460                 if (block1)
1461                         readahead_tree_block(root, block1, blocksize, 0);
1462                 if (block2)
1463                         readahead_tree_block(root, block2, blocksize, 0);
1464
1465                 if (block1) {
1466                         eb = read_tree_block(root, block1, blocksize, 0);
1467                         free_extent_buffer(eb);
1468                 }
1469                 if (block2) {
1470                         eb = read_tree_block(root, block2, blocksize, 0);
1471                         free_extent_buffer(eb);
1472                 }
1473         }
1474         return ret;
1475 }
1476
1477
1478 /*
1479  * when we walk down the tree, it is usually safe to unlock the higher layers
1480  * in the tree.  The exceptions are when our path goes through slot 0, because
1481  * operations on the tree might require changing key pointers higher up in the
1482  * tree.
1483  *
1484  * callers might also have set path->keep_locks, which tells this code to keep
1485  * the lock if the path points to the last slot in the block.  This is part of
1486  * walking through the tree, and selecting the next slot in the higher block.
1487  *
1488  * lowest_unlock sets the lowest level in the tree we're allowed to unlock.  so
1489  * if lowest_unlock is 1, level 0 won't be unlocked
1490  */
1491 static noinline void unlock_up(struct btrfs_path *path, int level,
1492                                int lowest_unlock)
1493 {
1494         int i;
1495         int skip_level = level;
1496         int no_skips = 0;
1497         struct extent_buffer *t;
1498
1499         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1500                 if (!path->nodes[i])
1501                         break;
1502                 if (!path->locks[i])
1503                         break;
1504                 if (!no_skips && path->slots[i] == 0) {
1505                         skip_level = i + 1;
1506                         continue;
1507                 }
1508                 if (!no_skips && path->keep_locks) {
1509                         u32 nritems;
1510                         t = path->nodes[i];
1511                         nritems = btrfs_header_nritems(t);
1512                         if (nritems < 1 || path->slots[i] >= nritems - 1) {
1513                                 skip_level = i + 1;
1514                                 continue;
1515                         }
1516                 }
1517                 if (skip_level < i && i >= lowest_unlock)
1518                         no_skips = 1;
1519
1520                 t = path->nodes[i];
1521                 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
1522                         btrfs_tree_unlock(t);
1523                         path->locks[i] = 0;
1524                 }
1525         }
1526 }
1527
1528 /*
1529  * This releases any locks held in the path starting at level and
1530  * going all the way up to the root.
1531  *
1532  * btrfs_search_slot will keep the lock held on higher nodes in a few
1533  * corner cases, such as COW of the block at slot zero in the node.  This
1534  * ignores those rules, and it should only be called when there are no
1535  * more updates to be done higher up in the tree.
1536  */
1537 noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
1538 {
1539         int i;
1540
1541         if (path->keep_locks)
1542                 return;
1543
1544         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1545                 if (!path->nodes[i])
1546                         continue;
1547                 if (!path->locks[i])
1548                         continue;
1549                 btrfs_tree_unlock(path->nodes[i]);
1550                 path->locks[i] = 0;
1551         }
1552 }
1553
1554 /*
1555  * helper function for btrfs_search_slot.  The goal is to find a block
1556  * in cache without setting the path to blocking.  If we find the block
1557  * we return zero and the path is unchanged.
1558  *
1559  * If we can't find the block, we set the path blocking and do some
1560  * reada.  -EAGAIN is returned and the search must be repeated.
1561  */
1562 static int
1563 read_block_for_search(struct btrfs_trans_handle *trans,
1564                        struct btrfs_root *root, struct btrfs_path *p,
1565                        struct extent_buffer **eb_ret, int level, int slot,
1566                        struct btrfs_key *key)
1567 {
1568         u64 blocknr;
1569         u64 gen;
1570         u32 blocksize;
1571         struct extent_buffer *b = *eb_ret;
1572         struct extent_buffer *tmp;
1573         int ret;
1574
1575         blocknr = btrfs_node_blockptr(b, slot);
1576         gen = btrfs_node_ptr_generation(b, slot);
1577         blocksize = btrfs_level_size(root, level - 1);
1578
1579         tmp = btrfs_find_tree_block(root, blocknr, blocksize);
1580         if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
1581                 /*
1582                  * we found an up to date block without sleeping, return
1583                  * right away
1584                  */
1585                 *eb_ret = tmp;
1586                 return 0;
1587         }
1588
1589         /*
1590          * reduce lock contention at high levels
1591          * of the btree by dropping locks before
1592          * we read.  Don't release the lock on the current
1593          * level because we need to walk this node to figure
1594          * out which blocks to read.
1595          */
1596         btrfs_unlock_up_safe(p, level + 1);
1597         btrfs_set_path_blocking(p);
1598
1599         if (tmp)
1600                 free_extent_buffer(tmp);
1601         if (p->reada)
1602                 reada_for_search(root, p, level, slot, key->objectid);
1603
1604         btrfs_release_path(NULL, p);
1605
1606         ret = -EAGAIN;
1607         tmp = read_tree_block(root, blocknr, blocksize, 0);
1608         if (tmp) {
1609                 /*
1610                  * If the read above didn't mark this buffer up to date,
1611                  * it will never end up being up to date.  Set ret to EIO now
1612                  * and give up so that our caller doesn't loop forever
1613                  * on our EAGAINs.
1614                  */
1615                 if (!btrfs_buffer_uptodate(tmp, 0))
1616                         ret = -EIO;
1617                 free_extent_buffer(tmp);
1618         }
1619         return ret;
1620 }
1621
1622 /*
1623  * helper function for btrfs_search_slot.  This does all of the checks
1624  * for node-level blocks and does any balancing required based on
1625  * the ins_len.
1626  *
1627  * If no extra work was required, zero is returned.  If we had to
1628  * drop the path, -EAGAIN is returned and btrfs_search_slot must
1629  * start over
1630  */
1631 static int
1632 setup_nodes_for_search(struct btrfs_trans_handle *trans,
1633                        struct btrfs_root *root, struct btrfs_path *p,
1634                        struct extent_buffer *b, int level, int ins_len)
1635 {
1636         int ret;
1637         if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1638             BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
1639                 int sret;
1640
1641                 sret = reada_for_balance(root, p, level);
1642                 if (sret)
1643                         goto again;
1644
1645                 btrfs_set_path_blocking(p);
1646                 sret = split_node(trans, root, p, level);
1647                 btrfs_clear_path_blocking(p, NULL);
1648
1649                 BUG_ON(sret > 0);
1650                 if (sret) {
1651                         ret = sret;
1652                         goto done;
1653                 }
1654                 b = p->nodes[level];
1655         } else if (ins_len < 0 && btrfs_header_nritems(b) <
1656                    BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
1657                 int sret;
1658
1659                 sret = reada_for_balance(root, p, level);
1660                 if (sret)
1661                         goto again;
1662
1663                 btrfs_set_path_blocking(p);
1664                 sret = balance_level(trans, root, p, level);
1665                 btrfs_clear_path_blocking(p, NULL);
1666
1667                 if (sret) {
1668                         ret = sret;
1669                         goto done;
1670                 }
1671                 b = p->nodes[level];
1672                 if (!b) {
1673                         btrfs_release_path(NULL, p);
1674                         goto again;
1675                 }
1676                 BUG_ON(btrfs_header_nritems(b) == 1);
1677         }
1678         return 0;
1679
1680 again:
1681         ret = -EAGAIN;
1682 done:
1683         return ret;
1684 }
1685
1686 /*
1687  * look for key in the tree.  path is filled in with nodes along the way
1688  * if key is found, we return zero and you can find the item in the leaf
1689  * level of the path (level 0)
1690  *
1691  * If the key isn't found, the path points to the slot where it should
1692  * be inserted, and 1 is returned.  If there are other errors during the
1693  * search a negative error number is returned.
1694  *
1695  * if ins_len > 0, nodes and leaves will be split as we walk down the
1696  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
1697  * possible)
1698  */
1699 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1700                       *root, struct btrfs_key *key, struct btrfs_path *p, int
1701                       ins_len, int cow)
1702 {
1703         struct extent_buffer *b;
1704         int slot;
1705         int ret;
1706         int err;
1707         int level;
1708         int lowest_unlock = 1;
1709         u8 lowest_level = 0;
1710
1711         lowest_level = p->lowest_level;
1712         WARN_ON(lowest_level && ins_len > 0);
1713         WARN_ON(p->nodes[0] != NULL);
1714
1715         if (ins_len < 0)
1716                 lowest_unlock = 2;
1717
1718 again:
1719         if (p->search_commit_root) {
1720                 b = root->commit_root;
1721                 extent_buffer_get(b);
1722                 if (!p->skip_locking)
1723                         btrfs_tree_lock(b);
1724         } else {
1725                 if (p->skip_locking)
1726                         b = btrfs_root_node(root);
1727                 else
1728                         b = btrfs_lock_root_node(root);
1729         }
1730
1731         while (b) {
1732                 level = btrfs_header_level(b);
1733
1734                 /*
1735                  * setup the path here so we can release it under lock
1736                  * contention with the cow code
1737                  */
1738                 p->nodes[level] = b;
1739                 if (!p->skip_locking)
1740                         p->locks[level] = 1;
1741
1742                 if (cow) {
1743                         /*
1744                          * if we don't really need to cow this block
1745                          * then we don't want to set the path blocking,
1746                          * so we test it here
1747                          */
1748                         if (!should_cow_block(trans, root, b))
1749                                 goto cow_done;
1750
1751                         btrfs_set_path_blocking(p);
1752
1753                         err = btrfs_cow_block(trans, root, b,
1754                                               p->nodes[level + 1],
1755                                               p->slots[level + 1], &b);
1756                         if (err) {
1757                                 ret = err;
1758                                 goto done;
1759                         }
1760                 }
1761 cow_done:
1762                 BUG_ON(!cow && ins_len);
1763                 if (level != btrfs_header_level(b))
1764                         WARN_ON(1);
1765                 level = btrfs_header_level(b);
1766
1767                 p->nodes[level] = b;
1768                 if (!p->skip_locking)
1769                         p->locks[level] = 1;
1770
1771                 btrfs_clear_path_blocking(p, NULL);
1772
1773                 /*
1774                  * we have a lock on b and as long as we aren't changing
1775                  * the tree, there is no way to for the items in b to change.
1776                  * It is safe to drop the lock on our parent before we
1777                  * go through the expensive btree search on b.
1778                  *
1779                  * If cow is true, then we might be changing slot zero,
1780                  * which may require changing the parent.  So, we can't
1781                  * drop the lock until after we know which slot we're
1782                  * operating on.
1783                  */
1784                 if (!cow)
1785                         btrfs_unlock_up_safe(p, level + 1);
1786
1787                 ret = check_block(root, p, level);
1788                 if (ret) {
1789                         ret = -1;
1790                         goto done;
1791                 }
1792
1793                 ret = bin_search(b, key, level, &slot);
1794
1795                 if (level != 0) {
1796                         int dec = 0;
1797                         if (ret && slot > 0) {
1798                                 dec = 1;
1799                                 slot -= 1;
1800                         }
1801                         p->slots[level] = slot;
1802                         err = setup_nodes_for_search(trans, root, p, b, level,
1803                                                      ins_len);
1804                         if (err == -EAGAIN)
1805                                 goto again;
1806                         if (err) {
1807                                 ret = err;
1808                                 goto done;
1809                         }
1810                         b = p->nodes[level];
1811                         slot = p->slots[level];
1812
1813                         unlock_up(p, level, lowest_unlock);
1814
1815                         if (level == lowest_level) {
1816                                 if (dec)
1817                                         p->slots[level]++;
1818                                 goto done;
1819                         }
1820
1821                         err = read_block_for_search(trans, root, p,
1822                                                     &b, level, slot, key);
1823                         if (err == -EAGAIN)
1824                                 goto again;
1825                         if (err) {
1826                                 ret = err;
1827                                 goto done;
1828                         }
1829
1830                         if (!p->skip_locking) {
1831                                 btrfs_clear_path_blocking(p, NULL);
1832                                 err = btrfs_try_spin_lock(b);
1833
1834                                 if (!err) {
1835                                         btrfs_set_path_blocking(p);
1836                                         btrfs_tree_lock(b);
1837                                         btrfs_clear_path_blocking(p, b);
1838                                 }
1839                         }
1840                 } else {
1841                         p->slots[level] = slot;
1842                         if (ins_len > 0 &&
1843                             btrfs_leaf_free_space(root, b) < ins_len) {
1844                                 btrfs_set_path_blocking(p);
1845                                 err = split_leaf(trans, root, key,
1846                                                  p, ins_len, ret == 0);
1847                                 btrfs_clear_path_blocking(p, NULL);
1848
1849                                 BUG_ON(err > 0);
1850                                 if (err) {
1851                                         ret = err;
1852                                         goto done;
1853                                 }
1854                         }
1855                         if (!p->search_for_split)
1856                                 unlock_up(p, level, lowest_unlock);
1857                         goto done;
1858                 }
1859         }
1860         ret = 1;
1861 done:
1862         /*
1863          * we don't really know what they plan on doing with the path
1864          * from here on, so for now just mark it as blocking
1865          */
1866         if (!p->leave_spinning)
1867                 btrfs_set_path_blocking(p);
1868         if (ret < 0)
1869                 btrfs_release_path(root, p);
1870         return ret;
1871 }
1872
1873 /*
1874  * adjust the pointers going up the tree, starting at level
1875  * making sure the right key of each node is points to 'key'.
1876  * This is used after shifting pointers to the left, so it stops
1877  * fixing up pointers when a given leaf/node is not in slot 0 of the
1878  * higher levels
1879  *
1880  * If this fails to write a tree block, it returns -1, but continues
1881  * fixing up the blocks in ram so the tree is consistent.
1882  */
1883 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1884                           struct btrfs_root *root, struct btrfs_path *path,
1885                           struct btrfs_disk_key *key, int level)
1886 {
1887         int i;
1888         int ret = 0;
1889         struct extent_buffer *t;
1890
1891         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1892                 int tslot = path->slots[i];
1893                 if (!path->nodes[i])
1894                         break;
1895                 t = path->nodes[i];
1896                 btrfs_set_node_key(t, key, tslot);
1897                 btrfs_mark_buffer_dirty(path->nodes[i]);
1898                 if (tslot != 0)
1899                         break;
1900         }
1901         return ret;
1902 }
1903
1904 /*
1905  * update item key.
1906  *
1907  * This function isn't completely safe. It's the caller's responsibility
1908  * that the new key won't break the order
1909  */
1910 int btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
1911                             struct btrfs_root *root, struct btrfs_path *path,
1912                             struct btrfs_key *new_key)
1913 {
1914         struct btrfs_disk_key disk_key;
1915         struct extent_buffer *eb;
1916         int slot;
1917
1918         eb = path->nodes[0];
1919         slot = path->slots[0];
1920         if (slot > 0) {
1921                 btrfs_item_key(eb, &disk_key, slot - 1);
1922                 if (comp_keys(&disk_key, new_key) >= 0)
1923                         return -1;
1924         }
1925         if (slot < btrfs_header_nritems(eb) - 1) {
1926                 btrfs_item_key(eb, &disk_key, slot + 1);
1927                 if (comp_keys(&disk_key, new_key) <= 0)
1928                         return -1;
1929         }
1930
1931         btrfs_cpu_key_to_disk(&disk_key, new_key);
1932         btrfs_set_item_key(eb, &disk_key, slot);
1933         btrfs_mark_buffer_dirty(eb);
1934         if (slot == 0)
1935                 fixup_low_keys(trans, root, path, &disk_key, 1);
1936         return 0;
1937 }
1938
1939 /*
1940  * try to push data from one node into the next node left in the
1941  * tree.
1942  *
1943  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1944  * error, and > 0 if there was no room in the left hand block.
1945  */
1946 static int push_node_left(struct btrfs_trans_handle *trans,
1947                           struct btrfs_root *root, struct extent_buffer *dst,
1948                           struct extent_buffer *src, int empty)
1949 {
1950         int push_items = 0;
1951         int src_nritems;
1952         int dst_nritems;
1953         int ret = 0;
1954
1955         src_nritems = btrfs_header_nritems(src);
1956         dst_nritems = btrfs_header_nritems(dst);
1957         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1958         WARN_ON(btrfs_header_generation(src) != trans->transid);
1959         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1960
1961         if (!empty && src_nritems <= 8)
1962                 return 1;
1963
1964         if (push_items <= 0)
1965                 return 1;
1966
1967         if (empty) {
1968                 push_items = min(src_nritems, push_items);
1969                 if (push_items < src_nritems) {
1970                         /* leave at least 8 pointers in the node if
1971                          * we aren't going to empty it
1972                          */
1973                         if (src_nritems - push_items < 8) {
1974                                 if (push_items <= 8)
1975                                         return 1;
1976                                 push_items -= 8;
1977                         }
1978                 }
1979         } else
1980                 push_items = min(src_nritems - 8, push_items);
1981
1982         copy_extent_buffer(dst, src,
1983                            btrfs_node_key_ptr_offset(dst_nritems),
1984                            btrfs_node_key_ptr_offset(0),
1985                            push_items * sizeof(struct btrfs_key_ptr));
1986
1987         if (push_items < src_nritems) {
1988                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1989                                       btrfs_node_key_ptr_offset(push_items),
1990                                       (src_nritems - push_items) *
1991                                       sizeof(struct btrfs_key_ptr));
1992         }
1993         btrfs_set_header_nritems(src, src_nritems - push_items);
1994         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1995         btrfs_mark_buffer_dirty(src);
1996         btrfs_mark_buffer_dirty(dst);
1997
1998         return ret;
1999 }
2000
2001 /*
2002  * try to push data from one node into the next node right in the
2003  * tree.
2004  *
2005  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2006  * error, and > 0 if there was no room in the right hand block.
2007  *
2008  * this will  only push up to 1/2 the contents of the left node over
2009  */
2010 static int balance_node_right(struct btrfs_trans_handle *trans,
2011                               struct btrfs_root *root,
2012                               struct extent_buffer *dst,
2013                               struct extent_buffer *src)
2014 {
2015         int push_items = 0;
2016         int max_push;
2017         int src_nritems;
2018         int dst_nritems;
2019         int ret = 0;
2020
2021         WARN_ON(btrfs_header_generation(src) != trans->transid);
2022         WARN_ON(btrfs_header_generation(dst) != trans->transid);
2023
2024         src_nritems = btrfs_header_nritems(src);
2025         dst_nritems = btrfs_header_nritems(dst);
2026         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
2027         if (push_items <= 0)
2028                 return 1;
2029
2030         if (src_nritems < 4)
2031                 return 1;
2032
2033         max_push = src_nritems / 2 + 1;
2034         /* don't try to empty the node */
2035         if (max_push >= src_nritems)
2036                 return 1;
2037
2038         if (max_push < push_items)
2039                 push_items = max_push;
2040
2041         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
2042                                       btrfs_node_key_ptr_offset(0),
2043                                       (dst_nritems) *
2044                                       sizeof(struct btrfs_key_ptr));
2045
2046         copy_extent_buffer(dst, src,
2047                            btrfs_node_key_ptr_offset(0),
2048                            btrfs_node_key_ptr_offset(src_nritems - push_items),
2049                            push_items * sizeof(struct btrfs_key_ptr));
2050
2051         btrfs_set_header_nritems(src, src_nritems - push_items);
2052         btrfs_set_header_nritems(dst, dst_nritems + push_items);
2053
2054         btrfs_mark_buffer_dirty(src);
2055         btrfs_mark_buffer_dirty(dst);
2056
2057         return ret;
2058 }
2059
2060 /*
2061  * helper function to insert a new root level in the tree.
2062  * A new node is allocated, and a single item is inserted to
2063  * point to the existing root
2064  *
2065  * returns zero on success or < 0 on failure.
2066  */
2067 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2068                            struct btrfs_root *root,
2069                            struct btrfs_path *path, int level)
2070 {
2071         u64 lower_gen;
2072         struct extent_buffer *lower;
2073         struct extent_buffer *c;
2074         struct extent_buffer *old;
2075         struct btrfs_disk_key lower_key;
2076
2077         BUG_ON(path->nodes[level]);
2078         BUG_ON(path->nodes[level-1] != root->node);
2079
2080         lower = path->nodes[level-1];
2081         if (level == 1)
2082                 btrfs_item_key(lower, &lower_key, 0);
2083         else
2084                 btrfs_node_key(lower, &lower_key, 0);
2085
2086         c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
2087                                    root->root_key.objectid, &lower_key,
2088                                    level, root->node->start, 0);
2089         if (IS_ERR(c))
2090                 return PTR_ERR(c);
2091
2092         root_add_used(root, root->nodesize);
2093
2094         memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
2095         btrfs_set_header_nritems(c, 1);
2096         btrfs_set_header_level(c, level);
2097         btrfs_set_header_bytenr(c, c->start);
2098         btrfs_set_header_generation(c, trans->transid);
2099         btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
2100         btrfs_set_header_owner(c, root->root_key.objectid);
2101
2102         write_extent_buffer(c, root->fs_info->fsid,
2103                             (unsigned long)btrfs_header_fsid(c),
2104                             BTRFS_FSID_SIZE);
2105
2106         write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
2107                             (unsigned long)btrfs_header_chunk_tree_uuid(c),
2108                             BTRFS_UUID_SIZE);
2109
2110         btrfs_set_node_key(c, &lower_key, 0);
2111         btrfs_set_node_blockptr(c, 0, lower->start);
2112         lower_gen = btrfs_header_generation(lower);
2113         WARN_ON(lower_gen != trans->transid);
2114
2115         btrfs_set_node_ptr_generation(c, 0, lower_gen);
2116
2117         btrfs_mark_buffer_dirty(c);
2118
2119         spin_lock(&root->node_lock);
2120         old = root->node;
2121         root->node = c;
2122         spin_unlock(&root->node_lock);
2123
2124         /* the super has an extra ref to root->node */
2125         free_extent_buffer(old);
2126
2127         add_root_to_dirty_list(root);
2128         extent_buffer_get(c);
2129         path->nodes[level] = c;
2130         path->locks[level] = 1;
2131         path->slots[level] = 0;
2132         return 0;
2133 }
2134
2135 /*
2136  * worker function to insert a single pointer in a node.
2137  * the node should have enough room for the pointer already
2138  *
2139  * slot and level indicate where you want the key to go, and
2140  * blocknr is the block the key points to.
2141  *
2142  * returns zero on success and < 0 on any error
2143  */
2144 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
2145                       *root, struct btrfs_path *path, struct btrfs_disk_key
2146                       *key, u64 bytenr, int slot, int level)
2147 {
2148         struct extent_buffer *lower;
2149         int nritems;
2150
2151         BUG_ON(!path->nodes[level]);
2152         btrfs_assert_tree_locked(path->nodes[level]);
2153         lower = path->nodes[level];
2154         nritems = btrfs_header_nritems(lower);
2155         BUG_ON(slot > nritems);
2156         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
2157                 BUG();
2158         if (slot != nritems) {
2159                 memmove_extent_buffer(lower,
2160                               btrfs_node_key_ptr_offset(slot + 1),
2161                               btrfs_node_key_ptr_offset(slot),
2162                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
2163         }
2164         btrfs_set_node_key(lower, key, slot);
2165         btrfs_set_node_blockptr(lower, slot, bytenr);
2166         WARN_ON(trans->transid == 0);
2167         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
2168         btrfs_set_header_nritems(lower, nritems + 1);
2169         btrfs_mark_buffer_dirty(lower);
2170         return 0;
2171 }
2172
2173 /*
2174  * split the node at the specified level in path in two.
2175  * The path is corrected to point to the appropriate node after the split
2176  *
2177  * Before splitting this tries to make some room in the node by pushing
2178  * left and right, if either one works, it returns right away.
2179  *
2180  * returns 0 on success and < 0 on failure
2181  */
2182 static noinline int split_node(struct btrfs_trans_handle *trans,
2183                                struct btrfs_root *root,
2184                                struct btrfs_path *path, int level)
2185 {
2186         struct extent_buffer *c;
2187         struct extent_buffer *split;
2188         struct btrfs_disk_key disk_key;
2189         int mid;
2190         int ret;
2191         int wret;
2192         u32 c_nritems;
2193
2194         c = path->nodes[level];
2195         WARN_ON(btrfs_header_generation(c) != trans->transid);
2196         if (c == root->node) {
2197                 /* trying to split the root, lets make a new one */
2198                 ret = insert_new_root(trans, root, path, level + 1);
2199                 if (ret)
2200                         return ret;
2201         } else {
2202                 ret = push_nodes_for_insert(trans, root, path, level);
2203                 c = path->nodes[level];
2204                 if (!ret && btrfs_header_nritems(c) <
2205                     BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
2206                         return 0;
2207                 if (ret < 0)
2208                         return ret;
2209         }
2210
2211         c_nritems = btrfs_header_nritems(c);
2212         mid = (c_nritems + 1) / 2;
2213         btrfs_node_key(c, &disk_key, mid);
2214
2215         split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
2216                                         root->root_key.objectid,
2217                                         &disk_key, level, c->start, 0);
2218         if (IS_ERR(split))
2219                 return PTR_ERR(split);
2220
2221         root_add_used(root, root->nodesize);
2222
2223         memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
2224         btrfs_set_header_level(split, btrfs_header_level(c));
2225         btrfs_set_header_bytenr(split, split->start);
2226         btrfs_set_header_generation(split, trans->transid);
2227         btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
2228         btrfs_set_header_owner(split, root->root_key.objectid);
2229         write_extent_buffer(split, root->fs_info->fsid,
2230                             (unsigned long)btrfs_header_fsid(split),
2231                             BTRFS_FSID_SIZE);
2232         write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
2233                             (unsigned long)btrfs_header_chunk_tree_uuid(split),
2234                             BTRFS_UUID_SIZE);
2235
2236
2237         copy_extent_buffer(split, c,
2238                            btrfs_node_key_ptr_offset(0),
2239                            btrfs_node_key_ptr_offset(mid),
2240                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
2241         btrfs_set_header_nritems(split, c_nritems - mid);
2242         btrfs_set_header_nritems(c, mid);
2243         ret = 0;
2244
2245         btrfs_mark_buffer_dirty(c);
2246         btrfs_mark_buffer_dirty(split);
2247
2248         wret = insert_ptr(trans, root, path, &disk_key, split->start,
2249                           path->slots[level + 1] + 1,
2250                           level + 1);
2251         if (wret)
2252                 ret = wret;
2253
2254         if (path->slots[level] >= mid) {
2255                 path->slots[level] -= mid;
2256                 btrfs_tree_unlock(c);
2257                 free_extent_buffer(c);
2258                 path->nodes[level] = split;
2259                 path->slots[level + 1] += 1;
2260         } else {
2261                 btrfs_tree_unlock(split);
2262                 free_extent_buffer(split);
2263         }
2264         return ret;
2265 }
2266
2267 /*
2268  * how many bytes are required to store the items in a leaf.  start
2269  * and nr indicate which items in the leaf to check.  This totals up the
2270  * space used both by the item structs and the item data
2271  */
2272 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
2273 {
2274         int data_len;
2275         int nritems = btrfs_header_nritems(l);
2276         int end = min(nritems, start + nr) - 1;
2277
2278         if (!nr)
2279                 return 0;
2280         data_len = btrfs_item_end_nr(l, start);
2281         data_len = data_len - btrfs_item_offset_nr(l, end);
2282         data_len += sizeof(struct btrfs_item) * nr;
2283         WARN_ON(data_len < 0);
2284         return data_len;
2285 }
2286
2287 /*
2288  * The space between the end of the leaf items and
2289  * the start of the leaf data.  IOW, how much room
2290  * the leaf has left for both items and data
2291  */
2292 noinline int btrfs_leaf_free_space(struct btrfs_root *root,
2293                                    struct extent_buffer *leaf)
2294 {
2295         int nritems = btrfs_header_nritems(leaf);
2296         int ret;
2297         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
2298         if (ret < 0) {
2299                 printk(KERN_CRIT "leaf free space ret %d, leaf data size %lu, "
2300                        "used %d nritems %d\n",
2301                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
2302                        leaf_space_used(leaf, 0, nritems), nritems);
2303         }
2304         return ret;
2305 }
2306
2307 /*
2308  * min slot controls the lowest index we're willing to push to the
2309  * right.  We'll push up to and including min_slot, but no lower
2310  */
2311 static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
2312                                       struct btrfs_root *root,
2313                                       struct btrfs_path *path,
2314                                       int data_size, int empty,
2315                                       struct extent_buffer *right,
2316                                       int free_space, u32 left_nritems,
2317                                       u32 min_slot)
2318 {
2319         struct extent_buffer *left = path->nodes[0];
2320         struct extent_buffer *upper = path->nodes[1];
2321         struct btrfs_disk_key disk_key;
2322         int slot;
2323         u32 i;
2324         int push_space = 0;
2325         int push_items = 0;
2326         struct btrfs_item *item;
2327         u32 nr;
2328         u32 right_nritems;
2329         u32 data_end;
2330         u32 this_item_size;
2331
2332         if (empty)
2333                 nr = 0;
2334         else
2335                 nr = max_t(u32, 1, min_slot);
2336
2337         if (path->slots[0] >= left_nritems)
2338                 push_space += data_size;
2339
2340         slot = path->slots[1];
2341         i = left_nritems - 1;
2342         while (i >= nr) {
2343                 item = btrfs_item_nr(left, i);
2344
2345                 if (!empty && push_items > 0) {
2346                         if (path->slots[0] > i)
2347                                 break;
2348                         if (path->slots[0] == i) {
2349                                 int space = btrfs_leaf_free_space(root, left);
2350                                 if (space + push_space * 2 > free_space)
2351                                         break;
2352                         }
2353                 }
2354
2355                 if (path->slots[0] == i)
2356                         push_space += data_size;
2357
2358                 if (!left->map_token) {
2359                         map_extent_buffer(left, (unsigned long)item,
2360                                         sizeof(struct btrfs_item),
2361                                         &left->map_token, &left->kaddr,
2362                                         &left->map_start, &left->map_len,
2363                                         KM_USER1);
2364                 }
2365
2366                 this_item_size = btrfs_item_size(left, item);
2367                 if (this_item_size + sizeof(*item) + push_space > free_space)
2368                         break;
2369
2370                 push_items++;
2371                 push_space += this_item_size + sizeof(*item);
2372                 if (i == 0)
2373                         break;
2374                 i--;
2375         }
2376         if (left->map_token) {
2377                 unmap_extent_buffer(left, left->map_token, KM_USER1);
2378                 left->map_token = NULL;
2379         }
2380
2381         if (push_items == 0)
2382                 goto out_unlock;
2383
2384         if (!empty && push_items == left_nritems)
2385                 WARN_ON(1);
2386
2387         /* push left to right */
2388         right_nritems = btrfs_header_nritems(right);
2389
2390         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
2391         push_space -= leaf_data_end(root, left);
2392
2393         /* make room in the right data area */
2394         data_end = leaf_data_end(root, right);
2395         memmove_extent_buffer(right,
2396                               btrfs_leaf_data(right) + data_end - push_space,
2397                               btrfs_leaf_data(right) + data_end,
2398                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
2399
2400         /* copy from the left data area */
2401         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
2402                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
2403                      btrfs_leaf_data(left) + leaf_data_end(root, left),
2404                      push_space);
2405
2406         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
2407                               btrfs_item_nr_offset(0),
2408                               right_nritems * sizeof(struct btrfs_item));
2409
2410         /* copy the items from left to right */
2411         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
2412                    btrfs_item_nr_offset(left_nritems - push_items),
2413                    push_items * sizeof(struct btrfs_item));
2414
2415         /* update the item pointers */
2416         right_nritems += push_items;
2417         btrfs_set_header_nritems(right, right_nritems);
2418         push_space = BTRFS_LEAF_DATA_SIZE(root);
2419         for (i = 0; i < right_nritems; i++) {
2420                 item = btrfs_item_nr(right, i);
2421                 if (!right->map_token) {
2422                         map_extent_buffer(right, (unsigned long)item,
2423                                         sizeof(struct btrfs_item),
2424                                         &right->map_token, &right->kaddr,
2425                                         &right->map_start, &right->map_len,
2426                                         KM_USER1);
2427                 }
2428                 push_space -= btrfs_item_size(right, item);
2429                 btrfs_set_item_offset(right, item, push_space);
2430         }
2431
2432         if (right->map_token) {
2433                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2434                 right->map_token = NULL;
2435         }
2436         left_nritems -= push_items;
2437         btrfs_set_header_nritems(left, left_nritems);
2438
2439         if (left_nritems)
2440                 btrfs_mark_buffer_dirty(left);
2441         else
2442                 clean_tree_block(trans, root, left);
2443
2444         btrfs_mark_buffer_dirty(right);
2445
2446         btrfs_item_key(right, &disk_key, 0);
2447         btrfs_set_node_key(upper, &disk_key, slot + 1);
2448         btrfs_mark_buffer_dirty(upper);
2449
2450         /* then fixup the leaf pointer in the path */
2451         if (path->slots[0] >= left_nritems) {
2452                 path->slots[0] -= left_nritems;
2453                 if (btrfs_header_nritems(path->nodes[0]) == 0)
2454                         clean_tree_block(trans, root, path->nodes[0]);
2455                 btrfs_tree_unlock(path->nodes[0]);
2456                 free_extent_buffer(path->nodes[0]);
2457                 path->nodes[0] = right;
2458                 path->slots[1] += 1;
2459         } else {
2460                 btrfs_tree_unlock(right);
2461                 free_extent_buffer(right);
2462         }
2463         return 0;
2464
2465 out_unlock:
2466         btrfs_tree_unlock(right);
2467         free_extent_buffer(right);
2468         return 1;
2469 }
2470
2471 /*
2472  * push some data in the path leaf to the right, trying to free up at
2473  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
2474  *
2475  * returns 1 if the push failed because the other node didn't have enough
2476  * room, 0 if everything worked out and < 0 if there were major errors.
2477  *
2478  * this will push starting from min_slot to the end of the leaf.  It won't
2479  * push any slot lower than min_slot
2480  */
2481 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
2482                            *root, struct btrfs_path *path,
2483                            int min_data_size, int data_size,
2484                            int empty, u32 min_slot)
2485 {
2486         struct extent_buffer *left = path->nodes[0];
2487         struct extent_buffer *right;
2488         struct extent_buffer *upper;
2489         int slot;
2490         int free_space;
2491         u32 left_nritems;
2492         int ret;
2493
2494         if (!path->nodes[1])
2495                 return 1;
2496
2497         slot = path->slots[1];
2498         upper = path->nodes[1];
2499         if (slot >= btrfs_header_nritems(upper) - 1)
2500                 return 1;
2501
2502         btrfs_assert_tree_locked(path->nodes[1]);
2503
2504         right = read_node_slot(root, upper, slot + 1);
2505         btrfs_tree_lock(right);
2506         btrfs_set_lock_blocking(right);
2507
2508         free_space = btrfs_leaf_free_space(root, right);
2509         if (free_space < data_size)
2510                 goto out_unlock;
2511
2512         /* cow and double check */
2513         ret = btrfs_cow_block(trans, root, right, upper,
2514                               slot + 1, &right);
2515         if (ret)
2516                 goto out_unlock;
2517
2518         free_space = btrfs_leaf_free_space(root, right);
2519         if (free_space < data_size)
2520                 goto out_unlock;
2521
2522         left_nritems = btrfs_header_nritems(left);
2523         if (left_nritems == 0)
2524                 goto out_unlock;
2525
2526         return __push_leaf_right(trans, root, path, min_data_size, empty,
2527                                 right, free_space, left_nritems, min_slot);
2528 out_unlock:
2529         btrfs_tree_unlock(right);
2530         free_extent_buffer(right);
2531         return 1;
2532 }
2533
2534 /*
2535  * push some data in the path leaf to the left, trying to free up at
2536  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
2537  *
2538  * max_slot can put a limit on how far into the leaf we'll push items.  The
2539  * item at 'max_slot' won't be touched.  Use (u32)-1 to make us do all the
2540  * items
2541  */
2542 static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
2543                                      struct btrfs_root *root,
2544                                      struct btrfs_path *path, int data_size,
2545                                      int empty, struct extent_buffer *left,
2546                                      int free_space, u32 right_nritems,
2547                                      u32 max_slot)
2548 {
2549         struct btrfs_disk_key disk_key;
2550         struct extent_buffer *right = path->nodes[0];
2551         int slot;
2552         int i;
2553         int push_space = 0;
2554         int push_items = 0;
2555         struct btrfs_item *item;
2556         u32 old_left_nritems;
2557         u32 nr;
2558         int ret = 0;
2559         int wret;
2560         u32 this_item_size;
2561         u32 old_left_item_size;
2562
2563         slot = path->slots[1];
2564
2565         if (empty)
2566                 nr = min(right_nritems, max_slot);
2567         else
2568                 nr = min(right_nritems - 1, max_slot);
2569
2570         for (i = 0; i < nr; i++) {
2571                 item = btrfs_item_nr(right, i);
2572                 if (!right->map_token) {
2573                         map_extent_buffer(right, (unsigned long)item,
2574                                         sizeof(struct btrfs_item),
2575                                         &right->map_token, &right->kaddr,
2576                                         &right->map_start, &right->map_len,
2577                                         KM_USER1);
2578                 }
2579
2580                 if (!empty && push_items > 0) {
2581                         if (path->slots[0] < i)
2582                                 break;
2583                         if (path->slots[0] == i) {
2584                                 int space = btrfs_leaf_free_space(root, right);
2585                                 if (space + push_space * 2 > free_space)
2586                                         break;
2587                         }
2588                 }
2589
2590                 if (path->slots[0] == i)
2591                         push_space += data_size;
2592
2593                 this_item_size = btrfs_item_size(right, item);
2594                 if (this_item_size + sizeof(*item) + push_space > free_space)
2595                         break;
2596
2597                 push_items++;
2598                 push_space += this_item_size + sizeof(*item);
2599         }
2600
2601         if (right->map_token) {
2602                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2603                 right->map_token = NULL;
2604         }
2605
2606         if (push_items == 0) {
2607                 ret = 1;
2608                 goto out;
2609         }
2610         if (!empty && push_items == btrfs_header_nritems(right))
2611                 WARN_ON(1);
2612
2613         /* push data from right to left */
2614         copy_extent_buffer(left, right,
2615                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
2616                            btrfs_item_nr_offset(0),
2617                            push_items * sizeof(struct btrfs_item));
2618
2619         push_space = BTRFS_LEAF_DATA_SIZE(root) -
2620                      btrfs_item_offset_nr(right, push_items - 1);
2621
2622         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
2623                      leaf_data_end(root, left) - push_space,
2624                      btrfs_leaf_data(right) +
2625                      btrfs_item_offset_nr(right, push_items - 1),
2626                      push_space);
2627         old_left_nritems = btrfs_header_nritems(left);
2628         BUG_ON(old_left_nritems <= 0);
2629
2630         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
2631         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
2632                 u32 ioff;
2633
2634                 item = btrfs_item_nr(left, i);
2635                 if (!left->map_token) {
2636                         map_extent_buffer(left, (unsigned long)item,
2637                                         sizeof(struct btrfs_item),
2638                                         &left->map_token, &left->kaddr,
2639                                         &left->map_start, &left->map_len,
2640                                         KM_USER1);
2641                 }
2642
2643                 ioff = btrfs_item_offset(left, item);
2644                 btrfs_set_item_offset(left, item,
2645                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
2646         }
2647         btrfs_set_header_nritems(left, old_left_nritems + push_items);
2648         if (left->map_token) {
2649                 unmap_extent_buffer(left, left->map_token, KM_USER1);
2650                 left->map_token = NULL;
2651         }
2652
2653         /* fixup right node */
2654         if (push_items > right_nritems) {
2655                 printk(KERN_CRIT "push items %d nr %u\n", push_items,
2656                        right_nritems);
2657                 WARN_ON(1);
2658         }
2659
2660         if (push_items < right_nritems) {
2661                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
2662                                                   leaf_data_end(root, right);
2663                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
2664                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
2665                                       btrfs_leaf_data(right) +
2666                                       leaf_data_end(root, right), push_space);
2667
2668                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
2669                               btrfs_item_nr_offset(push_items),
2670                              (btrfs_header_nritems(right) - push_items) *
2671                              sizeof(struct btrfs_item));
2672         }
2673         right_nritems -= push_items;
2674         btrfs_set_header_nritems(right, right_nritems);
2675         push_space = BTRFS_LEAF_DATA_SIZE(root);
2676         for (i = 0; i < right_nritems; i++) {
2677                 item = btrfs_item_nr(right, i);
2678
2679                 if (!right->map_token) {
2680                         map_extent_buffer(right, (unsigned long)item,
2681                                         sizeof(struct btrfs_item),
2682                                         &right->map_token, &right->kaddr,
2683                                         &right->map_start, &right->map_len,
2684                                         KM_USER1);
2685                 }
2686
2687                 push_space = push_space - btrfs_item_size(right, item);
2688                 btrfs_set_item_offset(right, item, push_space);
2689         }
2690         if (right->map_token) {
2691                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2692                 right->map_token = NULL;
2693         }
2694
2695         btrfs_mark_buffer_dirty(left);
2696         if (right_nritems)
2697                 btrfs_mark_buffer_dirty(right);
2698         else
2699                 clean_tree_block(trans, root, right);
2700
2701         btrfs_item_key(right, &disk_key, 0);
2702         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
2703         if (wret)
2704                 ret = wret;
2705
2706         /* then fixup the leaf pointer in the path */
2707         if (path->slots[0] < push_items) {
2708                 path->slots[0] += old_left_nritems;
2709                 btrfs_tree_unlock(path->nodes[0]);
2710                 free_extent_buffer(path->nodes[0]);
2711                 path->nodes[0] = left;
2712                 path->slots[1] -= 1;
2713         } else {
2714                 btrfs_tree_unlock(left);
2715                 free_extent_buffer(left);
2716                 path->slots[0] -= push_items;
2717         }
2718         BUG_ON(path->slots[0] < 0);
2719         return ret;
2720 out:
2721         btrfs_tree_unlock(left);
2722         free_extent_buffer(left);
2723         return ret;
2724 }
2725
2726 /*
2727  * push some data in the path leaf to the left, trying to free up at
2728  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
2729  *
2730  * max_slot can put a limit on how far into the leaf we'll push items.  The
2731  * item at 'max_slot' won't be touched.  Use (u32)-1 to make us push all the
2732  * items
2733  */
2734 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
2735                           *root, struct btrfs_path *path, int min_data_size,
2736                           int data_size, int empty, u32 max_slot)
2737 {
2738         struct extent_buffer *right = path->nodes[0];
2739         struct extent_buffer *left;
2740         int slot;
2741         int free_space;
2742         u32 right_nritems;
2743         int ret = 0;
2744
2745         slot = path->slots[1];
2746         if (slot == 0)
2747                 return 1;
2748         if (!path->nodes[1])
2749                 return 1;
2750
2751         right_nritems = btrfs_header_nritems(right);
2752         if (right_nritems == 0)
2753                 return 1;
2754
2755         btrfs_assert_tree_locked(path->nodes[1]);
2756
2757         left = read_node_slot(root, path->nodes[1], slot - 1);
2758         btrfs_tree_lock(left);
2759         btrfs_set_lock_blocking(left);
2760
2761         free_space = btrfs_leaf_free_space(root, left);
2762         if (free_space < data_size) {
2763                 ret = 1;
2764                 goto out;
2765         }
2766
2767         /* cow and double check */
2768         ret = btrfs_cow_block(trans, root, left,
2769                               path->nodes[1], slot - 1, &left);
2770         if (ret) {
2771                 /* we hit -ENOSPC, but it isn't fatal here */
2772                 ret = 1;
2773                 goto out;
2774         }
2775
2776         free_space = btrfs_leaf_free_space(root, left);
2777         if (free_space < data_size) {
2778                 ret = 1;
2779                 goto out;
2780         }
2781
2782         return __push_leaf_left(trans, root, path, min_data_size,
2783                                empty, left, free_space, right_nritems,
2784                                max_slot);
2785 out:
2786         btrfs_tree_unlock(left);
2787         free_extent_buffer(left);
2788         return ret;
2789 }
2790
2791 /*
2792  * split the path's leaf in two, making sure there is at least data_size
2793  * available for the resulting leaf level of the path.
2794  *
2795  * returns 0 if all went well and < 0 on failure.
2796  */
2797 static noinline int copy_for_split(struct btrfs_trans_handle *trans,
2798                                struct btrfs_root *root,
2799                                struct btrfs_path *path,
2800                                struct extent_buffer *l,
2801                                struct extent_buffer *right,
2802                                int slot, int mid, int nritems)
2803 {
2804         int data_copy_size;
2805         int rt_data_off;
2806         int i;
2807         int ret = 0;
2808         int wret;
2809         struct btrfs_disk_key disk_key;
2810
2811         nritems = nritems - mid;
2812         btrfs_set_header_nritems(right, nritems);
2813         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
2814
2815         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2816                            btrfs_item_nr_offset(mid),
2817                            nritems * sizeof(struct btrfs_item));
2818
2819         copy_extent_buffer(right, l,
2820                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2821                      data_copy_size, btrfs_leaf_data(l) +
2822                      leaf_data_end(root, l), data_copy_size);
2823
2824         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2825                       btrfs_item_end_nr(l, mid);
2826
2827         for (i = 0; i < nritems; i++) {
2828                 struct btrfs_item *item = btrfs_item_nr(right, i);
2829                 u32 ioff;
2830
2831                 if (!right->map_token) {
2832                         map_extent_buffer(right, (unsigned long)item,
2833                                         sizeof(struct btrfs_item),
2834                                         &right->map_token, &right->kaddr,
2835                                         &right->map_start, &right->map_len,
2836                                         KM_USER1);
2837                 }
2838
2839                 ioff = btrfs_item_offset(right, item);
2840                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2841         }
2842
2843         if (right->map_token) {
2844                 unmap_extent_buffer(right, right->map_token, KM_USER1);
2845                 right->map_token = NULL;
2846         }
2847
2848         btrfs_set_header_nritems(l, mid);
2849         ret = 0;
2850         btrfs_item_key(right, &disk_key, 0);
2851         wret = insert_ptr(trans, root, path, &disk_key, right->start,
2852                           path->slots[1] + 1, 1);
2853         if (wret)
2854                 ret = wret;
2855
2856         btrfs_mark_buffer_dirty(right);
2857         btrfs_mark_buffer_dirty(l);
2858         BUG_ON(path->slots[0] != slot);
2859
2860         if (mid <= slot) {
2861                 btrfs_tree_unlock(path->nodes[0]);
2862                 free_extent_buffer(path->nodes[0]);
2863                 path->nodes[0] = right;
2864                 path->slots[0] -= mid;
2865                 path->slots[1] += 1;
2866         } else {
2867                 btrfs_tree_unlock(right);
2868                 free_extent_buffer(right);
2869         }
2870
2871         BUG_ON(path->slots[0] < 0);
2872
2873         return ret;
2874 }
2875
2876 /*
2877  * double splits happen when we need to insert a big item in the middle
2878  * of a leaf.  A double split can leave us with 3 mostly empty leaves:
2879  * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
2880  *          A                 B                 C
2881  *
2882  * We avoid this by trying to push the items on either side of our target
2883  * into the adjacent leaves.  If all goes well we can avoid the double split
2884  * completely.
2885  */
2886 static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
2887                                           struct btrfs_root *root,
2888                                           struct btrfs_path *path,
2889                                           int data_size)
2890 {
2891         int ret;
2892         int progress = 0;
2893         int slot;
2894         u32 nritems;
2895
2896         slot = path->slots[0];
2897
2898         /*
2899          * try to push all the items after our slot into the
2900          * right leaf
2901          */
2902         ret = push_leaf_right(trans, root, path, 1, data_size, 0, slot);
2903         if (ret < 0)
2904                 return ret;
2905
2906         if (ret == 0)
2907                 progress++;
2908
2909         nritems = btrfs_header_nritems(path->nodes[0]);
2910         /*
2911          * our goal is to get our slot at the start or end of a leaf.  If
2912          * we've done so we're done
2913          */
2914         if (path->slots[0] == 0 || path->slots[0] == nritems)
2915                 return 0;
2916
2917         if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
2918                 return 0;
2919
2920         /* try to push all the items before our slot into the next leaf */
2921         slot = path->slots[0];
2922         ret = push_leaf_left(trans, root, path, 1, data_size, 0, slot);
2923         if (ret < 0)
2924                 return ret;
2925
2926         if (ret == 0)
2927                 progress++;
2928
2929         if (progress)
2930                 return 0;
2931         return 1;
2932 }
2933
2934 /*
2935  * split the path's leaf in two, making sure there is at least data_size
2936  * available for the resulting leaf level of the path.
2937  *
2938  * returns 0 if all went well and < 0 on failure.
2939  */
2940 static noinline int split_leaf(struct btrfs_trans_handle *trans,
2941                                struct btrfs_root *root,
2942                                struct btrfs_key *ins_key,
2943                                struct btrfs_path *path, int data_size,
2944                                int extend)
2945 {
2946         struct btrfs_disk_key disk_key;
2947         struct extent_buffer *l;
2948         u32 nritems;
2949         int mid;
2950         int slot;
2951         struct extent_buffer *right;
2952         int ret = 0;
2953         int wret;
2954         int split;
2955         int num_doubles = 0;
2956         int tried_avoid_double = 0;
2957
2958         l = path->nodes[0];
2959         slot = path->slots[0];
2960         if (extend && data_size + btrfs_item_size_nr(l, slot) +
2961             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root))
2962                 return -EOVERFLOW;
2963
2964         /* first try to make some room by pushing left and right */
2965         if (data_size) {
2966                 wret = push_leaf_right(trans, root, path, data_size,
2967                                        data_size, 0, 0);
2968                 if (wret < 0)
2969                         return wret;
2970                 if (wret) {
2971                         wret = push_leaf_left(trans, root, path, data_size,
2972                                               data_size, 0, (u32)-1);
2973                         if (wret < 0)
2974                                 return wret;
2975                 }
2976                 l = path->nodes[0];
2977
2978                 /* did the pushes work? */
2979                 if (btrfs_leaf_free_space(root, l) >= data_size)
2980                         return 0;
2981         }
2982
2983         if (!path->nodes[1]) {
2984                 ret = insert_new_root(trans, root, path, 1);
2985                 if (ret)
2986                         return ret;
2987         }
2988 again:
2989         split = 1;
2990         l = path->nodes[0];
2991         slot = path->slots[0];
2992         nritems = btrfs_header_nritems(l);
2993         mid = (nritems + 1) / 2;
2994
2995         if (mid <= slot) {
2996                 if (nritems == 1 ||
2997                     leaf_space_used(l, mid, nritems - mid) + data_size >
2998                         BTRFS_LEAF_DATA_SIZE(root)) {
2999                         if (slot >= nritems) {
3000                                 split = 0;
3001                         } else {
3002                                 mid = slot;
3003                                 if (mid != nritems &&
3004                                     leaf_space_used(l, mid, nritems - mid) +
3005                                     data_size > BTRFS_LEAF_DATA_SIZE(root)) {
3006                                         if (data_size && !tried_avoid_double)
3007                                                 goto push_for_double;
3008                                         split = 2;
3009                                 }
3010                         }
3011                 }
3012         } else {
3013                 if (leaf_space_used(l, 0, mid) + data_size >
3014                         BTRFS_LEAF_DATA_SIZE(root)) {
3015                         if (!extend && data_size && slot == 0) {
3016                                 split = 0;
3017                         } else if ((extend || !data_size) && slot == 0) {
3018                                 mid = 1;
3019                         } else {
3020                                 mid = slot;
3021                                 if (mid != nritems &&
3022                                     leaf_space_used(l, mid, nritems - mid) +
3023                                     data_size > BTRFS_LEAF_DATA_SIZE(root)) {
3024                                         if (data_size && !tried_avoid_double)
3025                                                 goto push_for_double;
3026                                         split = 2 ;
3027                                 }
3028                         }
3029                 }
3030         }
3031
3032         if (split == 0)
3033                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3034         else
3035                 btrfs_item_key(l, &disk_key, mid);
3036
3037         right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
3038                                         root->root_key.objectid,
3039                                         &disk_key, 0, l->start, 0);
3040         if (IS_ERR(right))
3041                 return PTR_ERR(right);
3042
3043         root_add_used(root, root->leafsize);
3044
3045         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
3046         btrfs_set_header_bytenr(right, right->start);
3047         btrfs_set_header_generation(right, trans->transid);
3048         btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
3049         btrfs_set_header_owner(right, root->root_key.objectid);
3050         btrfs_set_header_level(right, 0);
3051         write_extent_buffer(right, root->fs_info->fsid,
3052                             (unsigned long)btrfs_header_fsid(right),
3053                             BTRFS_FSID_SIZE);
3054
3055         write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
3056                             (unsigned long)btrfs_header_chunk_tree_uuid(right),
3057                             BTRFS_UUID_SIZE);
3058
3059         if (split == 0) {
3060                 if (mid <= slot) {
3061                         btrfs_set_header_nritems(right, 0);
3062                         wret = insert_ptr(trans, root, path,
3063                                           &disk_key, right->start,
3064                                           path->slots[1] + 1, 1);
3065                         if (wret)
3066                                 ret = wret;
3067
3068                         btrfs_tree_unlock(path->nodes[0]);
3069                         free_extent_buffer(path->nodes[0]);
3070                         path->nodes[0] = right;
3071                         path->slots[0] = 0;
3072                         path->slots[1] += 1;
3073                 } else {
3074                         btrfs_set_header_nritems(right, 0);
3075                         wret = insert_ptr(trans, root, path,
3076                                           &disk_key,
3077                                           right->start,
3078                                           path->slots[1], 1);
3079                         if (wret)
3080                                 ret = wret;
3081                         btrfs_tree_unlock(path->nodes[0]);
3082                         free_extent_buffer(path->nodes[0]);
3083                         path->nodes[0] = right;
3084                         path->slots[0] = 0;
3085                         if (path->slots[1] == 0) {
3086                                 wret = fixup_low_keys(trans, root,
3087                                                 path, &disk_key, 1);
3088                                 if (wret)
3089                                         ret = wret;
3090                         }
3091                 }
3092                 btrfs_mark_buffer_dirty(right);
3093                 return ret;
3094         }
3095
3096         ret = copy_for_split(trans, root, path, l, right, slot, mid, nritems);
3097         BUG_ON(ret);
3098
3099         if (split == 2) {
3100                 BUG_ON(num_doubles != 0);
3101                 num_doubles++;
3102                 goto again;
3103         }
3104
3105         return ret;
3106
3107 push_for_double:
3108         push_for_double_split(trans, root, path, data_size);
3109         tried_avoid_double = 1;
3110         if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
3111                 return 0;
3112         goto again;
3113 }
3114
3115 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3116                                          struct btrfs_root *root,
3117                                          struct btrfs_path *path, int ins_len)
3118 {
3119         struct btrfs_key key;
3120         struct extent_buffer *leaf;
3121         struct btrfs_file_extent_item *fi;
3122         u64 extent_len = 0;
3123         u32 item_size;
3124         int ret;
3125
3126         leaf = path->nodes[0];
3127         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3128
3129         BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3130                key.type != BTRFS_EXTENT_CSUM_KEY);
3131
3132         if (btrfs_leaf_free_space(root, leaf) >= ins_len)
3133                 return 0;
3134
3135         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3136         if (key.type == BTRFS_EXTENT_DATA_KEY) {
3137                 fi = btrfs_item_ptr(leaf, path->slots[0],
3138                                     struct btrfs_file_extent_item);
3139                 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3140         }
3141         btrfs_release_path(root, path);
3142
3143         path->keep_locks = 1;
3144         path->search_for_split = 1;
3145         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3146         path->search_for_split = 0;
3147         if (ret < 0)
3148                 goto err;
3149
3150         ret = -EAGAIN;
3151         leaf = path->nodes[0];
3152         /* if our item isn't there or got smaller, return now */
3153         if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0]))
3154                 goto err;
3155
3156         /* the leaf has  changed, it now has room.  return now */
3157         if (btrfs_leaf_free_space(root, path->nodes[0]) >= ins_len)
3158                 goto err;
3159
3160         if (key.type == BTRFS_EXTENT_DATA_KEY) {
3161                 fi = btrfs_item_ptr(leaf, path->slots[0],
3162                                     struct btrfs_file_extent_item);
3163                 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3164                         goto err;
3165         }
3166
3167         btrfs_set_path_blocking(path);
3168         ret = split_leaf(trans, root, &key, path, ins_len, 1);
3169         if (ret)
3170                 goto err;
3171
3172         path->keep_locks = 0;
3173         btrfs_unlock_up_safe(path, 1);
3174         return 0;
3175 err:
3176         path->keep_locks = 0;
3177         return ret;
3178 }
3179
3180 static noinline int split_item(struct btrfs_trans_handle *trans,
3181                                struct btrfs_root *root,
3182                                struct btrfs_path *path,
3183                                struct btrfs_key *new_key,
3184                                unsigned long split_offset)
3185 {
3186         struct extent_buffer *leaf;
3187         struct btrfs_item *item;
3188         struct btrfs_item *new_item;
3189         int slot;
3190         char *buf;
3191         u32 nritems;
3192         u32 item_size;
3193         u32 orig_offset;
3194         struct btrfs_disk_key disk_key;
3195
3196         leaf = path->nodes[0];
3197         BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
3198
3199         btrfs_set_path_blocking(path);
3200
3201         item = btrfs_item_nr(leaf, path->slots[0]);
3202         orig_offset = btrfs_item_offset(leaf, item);
3203         item_size = btrfs_item_size(leaf, item);
3204
3205         buf = kmalloc(item_size, GFP_NOFS);
3206         if (!buf)
3207                 return -ENOMEM;
3208
3209         read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3210                             path->slots[0]), item_size);
3211
3212         slot = path->slots[0] + 1;
3213         nritems = btrfs_header_nritems(leaf);
3214         if (slot != nritems) {
3215                 /* shift the items */
3216                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
3217                                 btrfs_item_nr_offset(slot),
3218                                 (nritems - slot) * sizeof(struct btrfs_item));
3219         }
3220
3221         btrfs_cpu_key_to_disk(&disk_key, new_key);
3222         btrfs_set_item_key(leaf, &disk_key, slot);
3223
3224         new_item = btrfs_item_nr(leaf, slot);
3225
3226         btrfs_set_item_offset(leaf, new_item, orig_offset);
3227         btrfs_set_item_size(leaf, new_item, item_size - split_offset);
3228
3229         btrfs_set_item_offset(leaf, item,
3230                               orig_offset + item_size - split_offset);
3231         btrfs_set_item_size(leaf, item, split_offset);
3232
3233         btrfs_set_header_nritems(leaf, nritems + 1);
3234
3235         /* write the data for the start of the original item */
3236         write_extent_buffer(leaf, buf,
3237                             btrfs_item_ptr_offset(leaf, path->slots[0]),
3238                             split_offset);
3239
3240         /* write the data for the new item */
3241         write_extent_buffer(leaf, buf + split_offset,
3242                             btrfs_item_ptr_offset(leaf, slot),
3243                             item_size - split_offset);
3244         btrfs_mark_buffer_dirty(leaf);
3245
3246         BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
3247         kfree(buf);
3248         return 0;
3249 }
3250
3251 /*
3252  * This function splits a single item into two items,
3253  * giving 'new_key' to the new item and splitting the
3254  * old one at split_offset (from the start of the item).
3255  *
3256  * The path may be released by this operation.  After
3257  * the split, the path is pointing to the old item.  The
3258  * new item is going to be in the same node as the old one.
3259  *
3260  * Note, the item being split must be smaller enough to live alone on
3261  * a tree block with room for one extra struct btrfs_item
3262  *
3263  * This allows us to split the item in place, keeping a lock on the
3264  * leaf the entire time.
3265  */
3266 int btrfs_split_item(struct btrfs_trans_handle *trans,
3267                      struct btrfs_root *root,
3268                      struct btrfs_path *path,
3269                      struct btrfs_key *new_key,
3270                      unsigned long split_offset)
3271 {
3272         int ret;
3273         ret = setup_leaf_for_split(trans, root, path,
3274                                    sizeof(struct btrfs_item));
3275         if (ret)
3276                 return ret;
3277
3278         ret = split_item(trans, root, path, new_key, split_offset);
3279         return ret;
3280 }
3281
3282 /*
3283  * This function duplicate a item, giving 'new_key' to the new item.
3284  * It guarantees both items live in the same tree leaf and the new item
3285  * is contiguous with the original item.
3286  *
3287  * This allows us to split file extent in place, keeping a lock on the
3288  * leaf the entire time.
3289  */
3290 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
3291                          struct btrfs_root *root,
3292                          struct btrfs_path *path,
3293                          struct btrfs_key *new_key)
3294 {
3295         struct extent_buffer *leaf;
3296         int ret;
3297         u32 item_size;
3298
3299         leaf = path->nodes[0];
3300         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3301         ret = setup_leaf_for_split(trans, root, path,
3302                                    item_size + sizeof(struct btrfs_item));
3303         if (ret)
3304                 return ret;
3305
3306         path->slots[0]++;
3307         ret = setup_items_for_insert(trans, root, path, new_key, &item_size,
3308                                      item_size, item_size +
3309                                      sizeof(struct btrfs_item), 1);
3310         BUG_ON(ret);
3311
3312         leaf = path->nodes[0];
3313         memcpy_extent_buffer(leaf,
3314                              btrfs_item_ptr_offset(leaf, path->slots[0]),
3315                              btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
3316                              item_size);
3317         return 0;
3318 }
3319
3320 /*
3321  * make the item pointed to by the path smaller.  new_size indicates
3322  * how small to make it, and from_end tells us if we just chop bytes
3323  * off the end of the item or if we shift the item to chop bytes off
3324  * the front.
3325  */
3326 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
3327                         struct btrfs_root *root,
3328                         struct btrfs_path *path,
3329                         u32 new_size, int from_end)
3330 {
3331         int ret = 0;
3332         int slot;
3333         int slot_orig;
3334         struct extent_buffer *leaf;
3335         struct btrfs_item *item;
3336         u32 nritems;
3337         unsigned int data_end;
3338         unsigned int old_data_start;
3339         unsigned int old_size;
3340         unsigned int size_diff;
3341         int i;
3342
3343         slot_orig = path->slots[0];
3344         leaf = path->nodes[0];
3345         slot = path->slots[0];
3346
3347         old_size = btrfs_item_size_nr(leaf, slot);
3348         if (old_size == new_size)
3349                 return 0;
3350
3351         nritems = btrfs_header_nritems(leaf);
3352         data_end = leaf_data_end(root, leaf);
3353
3354         old_data_start = btrfs_item_offset_nr(leaf, slot);
3355
3356         size_diff = old_size - new_size;
3357
3358         BUG_ON(slot < 0);
3359         BUG_ON(slot >= nritems);
3360
3361         /*
3362          * item0..itemN ... dataN.offset..dataN.size .. data0.size
3363          */
3364         /* first correct the data pointers */
3365         for (i = slot; i < nritems; i++) {
3366                 u32 ioff;
3367                 item = btrfs_item_nr(leaf, i);
3368
3369                 if (!leaf->map_token) {
3370                         map_extent_buffer(leaf, (unsigned long)item,
3371                                         sizeof(struct btrfs_item),
3372                                         &leaf->map_token, &leaf->kaddr,
3373                                         &leaf->map_start, &leaf->map_len,
3374                                         KM_USER1);
3375                 }
3376
3377                 ioff = btrfs_item_offset(leaf, item);
3378                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
3379         }
3380
3381         if (leaf->map_token) {
3382                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3383                 leaf->map_token = NULL;
3384         }
3385
3386         /* shift the data */
3387         if (from_end) {
3388                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3389                               data_end + size_diff, btrfs_leaf_data(leaf) +
3390                               data_end, old_data_start + new_size - data_end);
3391         } else {
3392                 struct btrfs_disk_key disk_key;
3393                 u64 offset;
3394
3395                 btrfs_item_key(leaf, &disk_key, slot);
3396
3397                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
3398                         unsigned long ptr;
3399                         struct btrfs_file_extent_item *fi;
3400
3401                         fi = btrfs_item_ptr(leaf, slot,
3402                                             struct btrfs_file_extent_item);
3403                         fi = (struct btrfs_file_extent_item *)(
3404                              (unsigned long)fi - size_diff);
3405
3406                         if (btrfs_file_extent_type(leaf, fi) ==
3407                             BTRFS_FILE_EXTENT_INLINE) {
3408                                 ptr = btrfs_item_ptr_offset(leaf, slot);
3409                                 memmove_extent_buffer(leaf, ptr,
3410                                       (unsigned long)fi,
3411                                       offsetof(struct btrfs_file_extent_item,
3412                                                  disk_bytenr));
3413                         }
3414                 }
3415
3416                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3417                               data_end + size_diff, btrfs_leaf_data(leaf) +
3418                               data_end, old_data_start - data_end);
3419
3420                 offset = btrfs_disk_key_offset(&disk_key);
3421                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
3422                 btrfs_set_item_key(leaf, &disk_key, slot);
3423                 if (slot == 0)
3424                         fixup_low_keys(trans, root, path, &disk_key, 1);
3425         }
3426
3427         item = btrfs_item_nr(leaf, slot);
3428         btrfs_set_item_size(leaf, item, new_size);
3429         btrfs_mark_buffer_dirty(leaf);
3430
3431         ret = 0;
3432         if (btrfs_leaf_free_space(root, leaf) < 0) {
3433                 btrfs_print_leaf(root, leaf);
3434                 BUG();
3435         }
3436         return ret;
3437 }
3438
3439 /*
3440  * make the item pointed to by the path bigger, data_size is the new size.
3441  */
3442 int btrfs_extend_item(struct btrfs_trans_handle *trans,
3443                       struct btrfs_root *root, struct btrfs_path *path,
3444                       u32 data_size)
3445 {
3446         int ret = 0;
3447         int slot;
3448         int slot_orig;
3449         struct extent_buffer *leaf;
3450         struct btrfs_item *item;
3451         u32 nritems;
3452         unsigned int data_end;
3453         unsigned int old_data;
3454         unsigned int old_size;
3455         int i;
3456
3457         slot_orig = path->slots[0];
3458         leaf = path->nodes[0];
3459
3460         nritems = btrfs_header_nritems(leaf);
3461         data_end = leaf_data_end(root, leaf);
3462
3463         if (btrfs_leaf_free_space(root, leaf) < data_size) {
3464                 btrfs_print_leaf(root, leaf);
3465                 BUG();
3466         }
3467         slot = path->slots[0];
3468         old_data = btrfs_item_end_nr(leaf, slot);
3469
3470         BUG_ON(slot < 0);
3471         if (slot >= nritems) {
3472                 btrfs_print_leaf(root, leaf);
3473                 printk(KERN_CRIT "slot %d too large, nritems %d\n",
3474                        slot, nritems);
3475                 BUG_ON(1);
3476         }
3477
3478         /*
3479          * item0..itemN ... dataN.offset..dataN.size .. data0.size
3480          */
3481         /* first correct the data pointers */
3482         for (i = slot; i < nritems; i++) {
3483                 u32 ioff;
3484                 item = btrfs_item_nr(leaf, i);
3485
3486                 if (!leaf->map_token) {
3487                         map_extent_buffer(leaf, (unsigned long)item,
3488                                         sizeof(struct btrfs_item),
3489                                         &leaf->map_token, &leaf->kaddr,
3490                                         &leaf->map_start, &leaf->map_len,
3491                                         KM_USER1);
3492                 }
3493                 ioff = btrfs_item_offset(leaf, item);
3494                 btrfs_set_item_offset(leaf, item, ioff - data_size);
3495         }
3496
3497         if (leaf->map_token) {
3498                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3499                 leaf->map_token = NULL;
3500         }
3501
3502         /* shift the data */
3503         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3504                       data_end - data_size, btrfs_leaf_data(leaf) +
3505                       data_end, old_data - data_end);
3506
3507         data_end = old_data;
3508         old_size = btrfs_item_size_nr(leaf, slot);
3509         item = btrfs_item_nr(leaf, slot);
3510         btrfs_set_item_size(leaf, item, old_size + data_size);
3511         btrfs_mark_buffer_dirty(leaf);
3512
3513         ret = 0;
3514         if (btrfs_leaf_free_space(root, leaf) < 0) {
3515                 btrfs_print_leaf(root, leaf);
3516                 BUG();
3517         }
3518         return ret;
3519 }
3520
3521 /*
3522  * Given a key and some data, insert items into the tree.
3523  * This does all the path init required, making room in the tree if needed.
3524  * Returns the number of keys that were inserted.
3525  */
3526 int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
3527                             struct btrfs_root *root,
3528                             struct btrfs_path *path,
3529                             struct btrfs_key *cpu_key, u32 *data_size,
3530                             int nr)
3531 {
3532         struct extent_buffer *leaf;
3533         struct btrfs_item *item;
3534         int ret = 0;
3535         int slot;
3536         int i;
3537         u32 nritems;
3538         u32 total_data = 0;
3539         u32 total_size = 0;
3540         unsigned int data_end;
3541         struct btrfs_disk_key disk_key;
3542         struct btrfs_key found_key;
3543
3544         for (i = 0; i < nr; i++) {
3545                 if (total_size + data_size[i] + sizeof(struct btrfs_item) >
3546                     BTRFS_LEAF_DATA_SIZE(root)) {
3547                         break;
3548                         nr = i;
3549                 }
3550                 total_data += data_size[i];
3551                 total_size += data_size[i] + sizeof(struct btrfs_item);
3552         }
3553         BUG_ON(nr == 0);
3554
3555         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
3556         if (ret == 0)
3557                 return -EEXIST;
3558         if (ret < 0)
3559                 goto out;
3560
3561         leaf = path->nodes[0];
3562
3563         nritems = btrfs_header_nritems(leaf);
3564         data_end = leaf_data_end(root, leaf);
3565
3566         if (btrfs_leaf_free_space(root, leaf) < total_size) {
3567                 for (i = nr; i >= 0; i--) {
3568                         total_data -= data_size[i];
3569                         total_size -= data_size[i] + sizeof(struct btrfs_item);
3570                         if (total_size < btrfs_leaf_free_space(root, leaf))
3571                                 break;
3572                 }
3573                 nr = i;
3574         }
3575
3576         slot = path->slots[0];
3577         BUG_ON(slot < 0);
3578
3579         if (slot != nritems) {
3580                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
3581
3582                 item = btrfs_item_nr(leaf, slot);
3583                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
3584
3585                 /* figure out how many keys we can insert in here */
3586                 total_data = data_size[0];
3587                 for (i = 1; i < nr; i++) {
3588                         if (btrfs_comp_cpu_keys(&found_key, cpu_key + i) <= 0)
3589                                 break;
3590                         total_data += data_size[i];
3591                 }
3592                 nr = i;
3593
3594                 if (old_data < data_end) {
3595                         btrfs_print_leaf(root, leaf);
3596                         printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
3597                                slot, old_data, data_end);
3598                         BUG_ON(1);
3599                 }
3600                 /*
3601                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
3602                  */
3603                 /* first correct the data pointers */
3604                 WARN_ON(leaf->map_token);
3605                 for (i = slot; i < nritems; i++) {
3606                         u32 ioff;
3607
3608                         item = btrfs_item_nr(leaf, i);
3609                         if (!leaf->map_token) {
3610                                 map_extent_buffer(leaf, (unsigned long)item,
3611                                         sizeof(struct btrfs_item),
3612                                         &leaf->map_token, &leaf->kaddr,
3613                                         &leaf->map_start, &leaf->map_len,
3614                                         KM_USER1);
3615                         }
3616
3617                         ioff = btrfs_item_offset(leaf, item);
3618                         btrfs_set_item_offset(leaf, item, ioff - total_data);
3619                 }
3620                 if (leaf->map_token) {
3621                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3622                         leaf->map_token = NULL;
3623                 }
3624
3625                 /* shift the items */
3626                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
3627                               btrfs_item_nr_offset(slot),
3628                               (nritems - slot) * sizeof(struct btrfs_item));
3629
3630                 /* shift the data */
3631                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3632                               data_end - total_data, btrfs_leaf_data(leaf) +
3633                               data_end, old_data - data_end);
3634                 data_end = old_data;
3635         } else {
3636                 /*
3637                  * this sucks but it has to be done, if we are inserting at
3638                  * the end of the leaf only insert 1 of the items, since we
3639                  * have no way of knowing whats on the next leaf and we'd have
3640                  * to drop our current locks to figure it out
3641                  */
3642                 nr = 1;
3643         }
3644
3645         /* setup the item for the new data */
3646         for (i = 0; i < nr; i++) {
3647                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
3648                 btrfs_set_item_key(leaf, &disk_key, slot + i);
3649                 item = btrfs_item_nr(leaf, slot + i);
3650                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
3651                 data_end -= data_size[i];
3652                 btrfs_set_item_size(leaf, item, data_size[i]);
3653         }
3654         btrfs_set_header_nritems(leaf, nritems + nr);
3655         btrfs_mark_buffer_dirty(leaf);
3656
3657         ret = 0;
3658         if (slot == 0) {
3659                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
3660                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
3661         }
3662
3663         if (btrfs_leaf_free_space(root, leaf) < 0) {
3664                 btrfs_print_leaf(root, leaf);
3665                 BUG();
3666         }
3667 out:
3668         if (!ret)
3669                 ret = nr;
3670         return ret;
3671 }
3672
3673 /*
3674  * this is a helper for btrfs_insert_empty_items, the main goal here is
3675  * to save stack depth by doing the bulk of the work in a function
3676  * that doesn't call btrfs_search_slot
3677  */
3678 static noinline_for_stack int
3679 setup_items_for_insert(struct btrfs_trans_handle *trans,
3680                       struct btrfs_root *root, struct btrfs_path *path,
3681                       struct btrfs_key *cpu_key, u32 *data_size,
3682                       u32 total_data, u32 total_size, int nr)
3683 {
3684         struct btrfs_item *item;
3685         int i;
3686         u32 nritems;
3687         unsigned int data_end;
3688         struct btrfs_disk_key disk_key;
3689         int ret;
3690         struct extent_buffer *leaf;
3691         int slot;
3692
3693         leaf = path->nodes[0];
3694         slot = path->slots[0];
3695
3696         nritems = btrfs_header_nritems(leaf);
3697         data_end = leaf_data_end(root, leaf);
3698
3699         if (btrfs_leaf_free_space(root, leaf) < total_size) {
3700                 btrfs_print_leaf(root, leaf);
3701                 printk(KERN_CRIT "not enough freespace need %u have %d\n",
3702                        total_size, btrfs_leaf_free_space(root, leaf));
3703                 BUG();
3704         }
3705
3706         if (slot != nritems) {
3707                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
3708
3709                 if (old_data < data_end) {
3710                         btrfs_print_leaf(root, leaf);
3711                         printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
3712                                slot, old_data, data_end);
3713                         BUG_ON(1);
3714                 }
3715                 /*
3716                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
3717                  */
3718                 /* first correct the data pointers */
3719                 WARN_ON(leaf->map_token);
3720                 for (i = slot; i < nritems; i++) {
3721                         u32 ioff;
3722
3723                         item = btrfs_item_nr(leaf, i);
3724                         if (!leaf->map_token) {
3725                                 map_extent_buffer(leaf, (unsigned long)item,
3726                                         sizeof(struct btrfs_item),
3727                                         &leaf->map_token, &leaf->kaddr,
3728                                         &leaf->map_start, &leaf->map_len,
3729                                         KM_USER1);
3730                         }
3731
3732                         ioff = btrfs_item_offset(leaf, item);
3733                         btrfs_set_item_offset(leaf, item, ioff - total_data);
3734                 }
3735                 if (leaf->map_token) {
3736                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3737                         leaf->map_token = NULL;
3738                 }
3739
3740                 /* shift the items */
3741                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
3742                               btrfs_item_nr_offset(slot),
3743                               (nritems - slot) * sizeof(struct btrfs_item));
3744
3745                 /* shift the data */
3746                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3747                               data_end - total_data, btrfs_leaf_data(leaf) +
3748                               data_end, old_data - data_end);
3749                 data_end = old_data;
3750         }
3751
3752         /* setup the item for the new data */
3753         for (i = 0; i < nr; i++) {
3754                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
3755                 btrfs_set_item_key(leaf, &disk_key, slot + i);
3756                 item = btrfs_item_nr(leaf, slot + i);
3757                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
3758                 data_end -= data_size[i];
3759                 btrfs_set_item_size(leaf, item, data_size[i]);
3760         }
3761
3762         btrfs_set_header_nritems(leaf, nritems + nr);
3763
3764         ret = 0;
3765         if (slot == 0) {
3766                 struct btrfs_disk_key disk_key;
3767                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
3768                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
3769         }
3770         btrfs_unlock_up_safe(path, 1);
3771         btrfs_mark_buffer_dirty(leaf);
3772
3773         if (btrfs_leaf_free_space(root, leaf) < 0) {
3774                 btrfs_print_leaf(root, leaf);
3775                 BUG();
3776         }
3777         return ret;
3778 }
3779
3780 /*
3781  * Given a key and some data, insert items into the tree.
3782  * This does all the path init required, making room in the tree if needed.
3783  */
3784 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
3785                             struct btrfs_root *root,
3786                             struct btrfs_path *path,
3787                             struct btrfs_key *cpu_key, u32 *data_size,
3788                             int nr)
3789 {
3790         struct extent_buffer *leaf;
3791         int ret = 0;
3792         int slot;
3793         int i;
3794         u32 total_size = 0;
3795         u32 total_data = 0;
3796
3797         for (i = 0; i < nr; i++)
3798                 total_data += data_size[i];
3799
3800         total_size = total_data + (nr * sizeof(struct btrfs_item));
3801         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
3802         if (ret == 0)
3803                 return -EEXIST;
3804         if (ret < 0)
3805                 goto out;
3806
3807         leaf = path->nodes[0];
3808         slot = path->slots[0];
3809         BUG_ON(slot < 0);
3810
3811         ret = setup_items_for_insert(trans, root, path, cpu_key, data_size,
3812                                total_data, total_size, nr);
3813
3814 out:
3815         return ret;
3816 }
3817
3818 /*
3819  * Given a key and some data, insert an item into the tree.
3820  * This does all the path init required, making room in the tree if needed.
3821  */
3822 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
3823                       *root, struct btrfs_key *cpu_key, void *data, u32
3824                       data_size)
3825 {
3826         int ret = 0;
3827         struct btrfs_path *path;
3828         struct extent_buffer *leaf;
3829         unsigned long ptr;
3830
3831         path = btrfs_alloc_path();
3832         BUG_ON(!path);
3833         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
3834         if (!ret) {
3835                 leaf = path->nodes[0];
3836                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
3837                 write_extent_buffer(leaf, data, ptr, data_size);
3838                 btrfs_mark_buffer_dirty(leaf);
3839         }
3840         btrfs_free_path(path);
3841         return ret;
3842 }
3843
3844 /*
3845  * delete the pointer from a given node.
3846  *
3847  * the tree should have been previously balanced so the deletion does not
3848  * empty a node.
3849  */
3850 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3851                    struct btrfs_path *path, int level, int slot)
3852 {
3853         struct extent_buffer *parent = path->nodes[level];
3854         u32 nritems;
3855         int ret = 0;
3856         int wret;
3857
3858         nritems = btrfs_header_nritems(parent);
3859         if (slot != nritems - 1) {
3860                 memmove_extent_buffer(parent,
3861                               btrfs_node_key_ptr_offset(slot),
3862                               btrfs_node_key_ptr_offset(slot + 1),
3863                               sizeof(struct btrfs_key_ptr) *
3864                               (nritems - slot - 1));
3865         }
3866         nritems--;
3867         btrfs_set_header_nritems(parent, nritems);
3868         if (nritems == 0 && parent == root->node) {
3869                 BUG_ON(btrfs_header_level(root->node) != 1);
3870                 /* just turn the root into a leaf and break */
3871                 btrfs_set_header_level(root->node, 0);
3872         } else if (slot == 0) {
3873                 struct btrfs_disk_key disk_key;
3874
3875                 btrfs_node_key(parent, &disk_key, 0);
3876                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
3877                 if (wret)
3878                         ret = wret;
3879         }
3880         btrfs_mark_buffer_dirty(parent);
3881         return ret;
3882 }
3883
3884 /*
3885  * a helper function to delete the leaf pointed to by path->slots[1] and
3886  * path->nodes[1].
3887  *
3888  * This deletes the pointer in path->nodes[1] and frees the leaf
3889  * block extent.  zero is returned if it all worked out, < 0 otherwise.
3890  *
3891  * The path must have already been setup for deleting the leaf, including
3892  * all the proper balancing.  path->nodes[1] must be locked.
3893  */
3894 static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
3895                                    struct btrfs_root *root,
3896                                    struct btrfs_path *path,
3897                                    struct extent_buffer *leaf)
3898 {
3899         int ret;
3900
3901         WARN_ON(btrfs_header_generation(leaf) != trans->transid);
3902         ret = del_ptr(trans, root, path, 1, path->slots[1]);
3903         if (ret)
3904                 return ret;
3905
3906         /*
3907          * btrfs_free_extent is expensive, we want to make sure we
3908          * aren't holding any locks when we call it
3909          */
3910         btrfs_unlock_up_safe(path, 0);
3911
3912         root_sub_used(root, leaf->len);
3913
3914         btrfs_free_tree_block(trans, root, leaf, 0, 1);
3915         return 0;
3916 }
3917 /*
3918  * delete the item at the leaf level in path.  If that empties
3919  * the leaf, remove it from the tree
3920  */
3921 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3922                     struct btrfs_path *path, int slot, int nr)
3923 {
3924         struct extent_buffer *leaf;
3925         struct btrfs_item *item;
3926         int last_off;
3927         int dsize = 0;
3928         int ret = 0;
3929         int wret;
3930         int i;
3931         u32 nritems;
3932
3933         leaf = path->nodes[0];
3934         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
3935
3936         for (i = 0; i < nr; i++)
3937                 dsize += btrfs_item_size_nr(leaf, slot + i);
3938
3939         nritems = btrfs_header_nritems(leaf);
3940
3941         if (slot + nr != nritems) {
3942                 int data_end = leaf_data_end(root, leaf);
3943
3944                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3945                               data_end + dsize,
3946                               btrfs_leaf_data(leaf) + data_end,
3947                               last_off - data_end);
3948
3949                 for (i = slot + nr; i < nritems; i++) {
3950                         u32 ioff;
3951
3952                         item = btrfs_item_nr(leaf, i);
3953                         if (!leaf->map_token) {
3954                                 map_extent_buffer(leaf, (unsigned long)item,
3955                                         sizeof(struct btrfs_item),
3956                                         &leaf->map_token, &leaf->kaddr,
3957                                         &leaf->map_start, &leaf->map_len,
3958                                         KM_USER1);
3959                         }
3960                         ioff = btrfs_item_offset(leaf, item);
3961                         btrfs_set_item_offset(leaf, item, ioff + dsize);
3962                 }
3963
3964                 if (leaf->map_token) {
3965                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
3966                         leaf->map_token = NULL;
3967                 }
3968
3969                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
3970                               btrfs_item_nr_offset(slot + nr),
3971                               sizeof(struct btrfs_item) *
3972                               (nritems - slot - nr));
3973         }
3974         btrfs_set_header_nritems(leaf, nritems - nr);
3975         nritems -= nr;
3976
3977         /* delete the leaf if we've emptied it */
3978         if (nritems == 0) {
3979                 if (leaf == root->node) {
3980                         btrfs_set_header_level(leaf, 0);
3981                 } else {
3982                         btrfs_set_path_blocking(path);
3983                         clean_tree_block(trans, root, leaf);
3984                         ret = btrfs_del_leaf(trans, root, path, leaf);
3985                         BUG_ON(ret);
3986                 }
3987         } else {
3988                 int used = leaf_space_used(leaf, 0, nritems);
3989                 if (slot == 0) {
3990                         struct btrfs_disk_key disk_key;
3991
3992                         btrfs_item_key(leaf, &disk_key, 0);
3993                         wret = fixup_low_keys(trans, root, path,
3994                                               &disk_key, 1);
3995                         if (wret)
3996                                 ret = wret;
3997                 }
3998
3999                 /* delete the leaf if it is mostly empty */
4000                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
4001                         /* push_leaf_left fixes the path.
4002                          * make sure the path still points to our leaf
4003                          * for possible call to del_ptr below
4004                          */
4005                         slot = path->slots[1];
4006                         extent_buffer_get(leaf);
4007
4008                         btrfs_set_path_blocking(path);
4009                         wret = push_leaf_left(trans, root, path, 1, 1,
4010                                               1, (u32)-1);
4011                         if (wret < 0 && wret != -ENOSPC)
4012                                 ret = wret;
4013
4014                         if (path->nodes[0] == leaf &&
4015                             btrfs_header_nritems(leaf)) {
4016                                 wret = push_leaf_right(trans, root, path, 1,
4017                                                        1, 1, 0);
4018                                 if (wret < 0 && wret != -ENOSPC)
4019                                         ret = wret;
4020                         }
4021
4022                         if (btrfs_header_nritems(leaf) == 0) {
4023                                 path->slots[1] = slot;
4024                                 ret = btrfs_del_leaf(trans, root, path, leaf);
4025                                 BUG_ON(ret);
4026                                 free_extent_buffer(leaf);
4027                         } else {
4028                                 /* if we're still in the path, make sure
4029                                  * we're dirty.  Otherwise, one of the
4030                                  * push_leaf functions must have already
4031                                  * dirtied this buffer
4032                                  */
4033                                 if (path->nodes[0] == leaf)
4034                                         btrfs_mark_buffer_dirty(leaf);
4035                                 free_extent_buffer(leaf);
4036                         }
4037                 } else {
4038                         btrfs_mark_buffer_dirty(leaf);
4039                 }
4040         }
4041         return ret;
4042 }
4043
4044 /*
4045  * search the tree again to find a leaf with lesser keys
4046  * returns 0 if it found something or 1 if there are no lesser leaves.
4047  * returns < 0 on io errors.
4048  *
4049  * This may release the path, and so you may lose any locks held at the
4050  * time you call it.
4051  */
4052 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
4053 {
4054         struct btrfs_key key;
4055         struct btrfs_disk_key found_key;
4056         int ret;
4057
4058         btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
4059
4060         if (key.offset > 0)
4061                 key.offset--;
4062         else if (key.type > 0)
4063                 key.type--;
4064         else if (key.objectid > 0)
4065                 key.objectid--;
4066         else
4067                 return 1;
4068
4069         btrfs_release_path(root, path);
4070         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4071         if (ret < 0)
4072                 return ret;
4073         btrfs_item_key(path->nodes[0], &found_key, 0);
4074         ret = comp_keys(&found_key, &key);
4075         if (ret < 0)
4076                 return 0;
4077         return 1;
4078 }
4079
4080 /*
4081  * A helper function to walk down the tree starting at min_key, and looking
4082  * for nodes or leaves that are either in cache or have a minimum
4083  * transaction id.  This is used by the btree defrag code, and tree logging
4084  *
4085  * This does not cow, but it does stuff the starting key it finds back
4086  * into min_key, so you can call btrfs_search_slot with cow=1 on the
4087  * key and get a writable path.
4088  *
4089  * This does lock as it descends, and path->keep_locks should be set
4090  * to 1 by the caller.
4091  *
4092  * This honors path->lowest_level to prevent descent past a given level
4093  * of the tree.
4094  *
4095  * min_trans indicates the oldest transaction that you are interested
4096  * in walking through.  Any nodes or leaves older than min_trans are
4097  * skipped over (without reading them).
4098  *
4099  * returns zero if something useful was found, < 0 on error and 1 if there
4100  * was nothing in the tree that matched the search criteria.
4101  */
4102 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4103                          struct btrfs_key *max_key,
4104                          struct btrfs_path *path, int cache_only,
4105                          u64 min_trans)
4106 {
4107         struct extent_buffer *cur;
4108         struct btrfs_key found_key;
4109         int slot;
4110         int sret;
4111         u32 nritems;
4112         int level;
4113         int ret = 1;
4114
4115         WARN_ON(!path->keep_locks);
4116 again:
4117         cur = btrfs_lock_root_node(root);
4118         level = btrfs_header_level(cur);
4119         WARN_ON(path->nodes[level]);
4120         path->nodes[level] = cur;
4121         path->locks[level] = 1;
4122
4123         if (btrfs_header_generation(cur) < min_trans) {
4124                 ret = 1;
4125                 goto out;
4126         }
4127         while (1) {
4128                 nritems = btrfs_header_nritems(cur);
4129                 level = btrfs_header_level(cur);
4130                 sret = bin_search(cur, min_key, level, &slot);
4131
4132                 /* at the lowest level, we're done, setup the path and exit */
4133                 if (level == path->lowest_level) {
4134                         if (slot >= nritems)
4135                                 goto find_next_key;
4136                         ret = 0;
4137                         path->slots[level] = slot;
4138                         btrfs_item_key_to_cpu(cur, &found_key, slot);
4139                         goto out;
4140                 }
4141                 if (sret && slot > 0)
4142                         slot--;
4143                 /*
4144                  * check this node pointer against the cache_only and
4145                  * min_trans parameters.  If it isn't in cache or is too
4146                  * old, skip to the next one.
4147                  */
4148                 while (slot < nritems) {
4149                         u64 blockptr;
4150                         u64 gen;
4151                         struct extent_buffer *tmp;
4152                         struct btrfs_disk_key disk_key;
4153
4154                         blockptr = btrfs_node_blockptr(cur, slot);
4155                         gen = btrfs_node_ptr_generation(cur, slot);
4156                         if (gen < min_trans) {
4157                                 slot++;
4158                                 continue;
4159                         }
4160                         if (!cache_only)
4161                                 break;
4162
4163                         if (max_key) {
4164                                 btrfs_node_key(cur, &disk_key, slot);
4165                                 if (comp_keys(&disk_key, max_key) >= 0) {
4166                                         ret = 1;
4167                                         goto out;
4168                                 }
4169                         }
4170
4171                         tmp = btrfs_find_tree_block(root, blockptr,
4172                                             btrfs_level_size(root, level - 1));
4173
4174                         if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
4175                                 free_extent_buffer(tmp);
4176                                 break;
4177                         }
4178                         if (tmp)
4179                                 free_extent_buffer(tmp);
4180                         slot++;
4181                 }
4182 find_next_key:
4183                 /*
4184                  * we didn't find a candidate key in this node, walk forward
4185                  * and find another one
4186                  */
4187                 if (slot >= nritems) {
4188                         path->slots[level] = slot;
4189                         btrfs_set_path_blocking(path);
4190                         sret = btrfs_find_next_key(root, path, min_key, level,
4191                                                   cache_only, min_trans);
4192                         if (sret == 0) {
4193                                 btrfs_release_path(root, path);
4194                                 goto again;
4195                         } else {
4196                                 goto out;
4197                         }
4198                 }
4199                 /* save our key for returning back */
4200                 btrfs_node_key_to_cpu(cur, &found_key, slot);
4201                 path->slots[level] = slot;
4202                 if (level == path->lowest_level) {
4203                         ret = 0;
4204                         unlock_up(path, level, 1);
4205                         goto out;
4206                 }
4207                 btrfs_set_path_blocking(path);
4208                 cur = read_node_slot(root, cur, slot);
4209
4210                 btrfs_tree_lock(cur);
4211
4212                 path->locks[level - 1] = 1;
4213                 path->nodes[level - 1] = cur;
4214                 unlock_up(path, level, 1);
4215                 btrfs_clear_path_blocking(path, NULL);
4216         }
4217 out:
4218         if (ret == 0)
4219                 memcpy(min_key, &found_key, sizeof(found_key));
4220         btrfs_set_path_blocking(path);
4221         return ret;
4222 }
4223
4224 /*
4225  * this is similar to btrfs_next_leaf, but does not try to preserve
4226  * and fixup the path.  It looks for and returns the next key in the
4227  * tree based on the current path and the cache_only and min_trans
4228  * parameters.
4229  *
4230  * 0 is returned if another key is found, < 0 if there are any errors
4231  * and 1 is returned if there are no higher keys in the tree
4232  *
4233  * path->keep_locks should be set to 1 on the search made before
4234  * calling this function.
4235  */
4236 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4237                         struct btrfs_key *key, int level,
4238                         int cache_only, u64 min_trans)
4239 {
4240         int slot;
4241         struct extent_buffer *c;
4242
4243         WARN_ON(!path->keep_locks);
4244         while (level < BTRFS_MAX_LEVEL) {
4245                 if (!path->nodes[level])
4246                         return 1;
4247
4248                 slot = path->slots[level] + 1;
4249                 c = path->nodes[level];
4250 next:
4251                 if (slot >= btrfs_header_nritems(c)) {
4252                         int ret;
4253                         int orig_lowest;
4254                         struct btrfs_key cur_key;
4255                         if (level + 1 >= BTRFS_MAX_LEVEL ||
4256                             !path->nodes[level + 1])
4257                                 return 1;
4258
4259                         if (path->locks[level + 1]) {
4260                                 level++;
4261                                 continue;
4262                         }
4263
4264                         slot = btrfs_header_nritems(c) - 1;
4265                         if (level == 0)
4266                                 btrfs_item_key_to_cpu(c, &cur_key, slot);
4267                         else
4268                                 btrfs_node_key_to_cpu(c, &cur_key, slot);
4269
4270                         orig_lowest = path->lowest_level;
4271                         btrfs_release_path(root, path);
4272                         path->lowest_level = level;
4273                         ret = btrfs_search_slot(NULL, root, &cur_key, path,
4274                                                 0, 0);
4275                         path->lowest_level = orig_lowest;
4276                         if (ret < 0)
4277                                 return ret;
4278
4279                         c = path->nodes[level];
4280                         slot = path->slots[level];
4281                         if (ret == 0)
4282                                 slot++;
4283                         goto next;
4284                 }
4285
4286                 if (level == 0)
4287                         btrfs_item_key_to_cpu(c, key, slot);
4288                 else {
4289                         u64 blockptr = btrfs_node_blockptr(c, slot);
4290                         u64 gen = btrfs_node_ptr_generation(c, slot);
4291
4292                         if (cache_only) {
4293                                 struct extent_buffer *cur;
4294                                 cur = btrfs_find_tree_block(root, blockptr,
4295                                             btrfs_level_size(root, level - 1));
4296                                 if (!cur || !btrfs_buffer_uptodate(cur, gen)) {
4297                                         slot++;
4298                                         if (cur)
4299                                                 free_extent_buffer(cur);
4300                                         goto next;
4301                                 }
4302                                 free_extent_buffer(cur);
4303                         }
4304                         if (gen < min_trans) {
4305                                 slot++;
4306                                 goto next;
4307                         }
4308                         btrfs_node_key_to_cpu(c, key, slot);
4309                 }
4310                 return 0;
4311         }
4312         return 1;
4313 }
4314
4315 /*
4316  * search the tree again to find a leaf with greater keys
4317  * returns 0 if it found something or 1 if there are no greater leaves.
4318  * returns < 0 on io errors.
4319  */
4320 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
4321 {
4322         int slot;
4323         int level;
4324         struct extent_buffer *c;
4325         struct extent_buffer *next;
4326         struct btrfs_key key;
4327         u32 nritems;
4328         int ret;
4329         int old_spinning = path->leave_spinning;
4330         int force_blocking = 0;
4331
4332         nritems = btrfs_header_nritems(path->nodes[0]);
4333         if (nritems == 0)
4334                 return 1;
4335
4336         /*
4337          * we take the blocks in an order that upsets lockdep.  Using
4338          * blocking mode is the only way around it.
4339          */
4340 #ifdef CONFIG_DEBUG_LOCK_ALLOC
4341         force_blocking = 1;
4342 #endif
4343
4344         btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4345 again:
4346         level = 1;
4347         next = NULL;
4348         btrfs_release_path(root, path);
4349
4350         path->keep_locks = 1;
4351
4352         if (!force_blocking)
4353                 path->leave_spinning = 1;
4354
4355         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4356         path->keep_locks = 0;
4357
4358         if (ret < 0)
4359                 return ret;
4360
4361         nritems = btrfs_header_nritems(path->nodes[0]);
4362         /*
4363          * by releasing the path above we dropped all our locks.  A balance
4364          * could have added more items next to the key that used to be
4365          * at the very end of the block.  So, check again here and
4366          * advance the path if there are now more items available.
4367          */
4368         if (nritems > 0 && path->slots[0] < nritems - 1) {
4369                 if (ret == 0)
4370                         path->slots[0]++;
4371                 ret = 0;
4372                 goto done;
4373         }
4374
4375         while (level < BTRFS_MAX_LEVEL) {
4376                 if (!path->nodes[level]) {
4377                         ret = 1;
4378                         goto done;
4379                 }
4380
4381                 slot = path->slots[level] + 1;
4382                 c = path->nodes[level];
4383                 if (slot >= btrfs_header_nritems(c)) {
4384                         level++;
4385                         if (level == BTRFS_MAX_LEVEL) {
4386                                 ret = 1;
4387                                 goto done;
4388                         }
4389                         continue;
4390                 }
4391
4392                 if (next) {
4393                         btrfs_tree_unlock(next);
4394                         free_extent_buffer(next);
4395                 }
4396
4397                 next = c;
4398                 ret = read_block_for_search(NULL, root, path, &next, level,
4399                                             slot, &key);
4400                 if (ret == -EAGAIN)
4401                         goto again;
4402
4403                 if (ret < 0) {
4404                         btrfs_release_path(root, path);
4405                         goto done;
4406                 }
4407
4408                 if (!path->skip_locking) {
4409                         ret = btrfs_try_spin_lock(next);
4410                         if (!ret) {
4411                                 btrfs_set_path_blocking(path);
4412                                 btrfs_tree_lock(next);
4413                                 if (!force_blocking)
4414                                         btrfs_clear_path_blocking(path, next);
4415                         }
4416                         if (force_blocking)
4417                                 btrfs_set_lock_blocking(next);
4418                 }
4419                 break;
4420         }
4421         path->slots[level] = slot;
4422         while (1) {
4423                 level--;
4424                 c = path->nodes[level];
4425                 if (path->locks[level])
4426                         btrfs_tree_unlock(c);
4427
4428                 free_extent_buffer(c);
4429                 path->nodes[level] = next;
4430                 path->slots[level] = 0;
4431                 if (!path->skip_locking)
4432                         path->locks[level] = 1;
4433
4434                 if (!level)
4435                         break;
4436
4437                 ret = read_block_for_search(NULL, root, path, &next, level,
4438                                             0, &key);
4439                 if (ret == -EAGAIN)
4440                         goto again;
4441
4442                 if (ret < 0) {
4443                         btrfs_release_path(root, path);
4444                         goto done;
4445                 }
4446
4447                 if (!path->skip_locking) {
4448                         btrfs_assert_tree_locked(path->nodes[level]);
4449                         ret = btrfs_try_spin_lock(next);
4450                         if (!ret) {
4451                                 btrfs_set_path_blocking(path);
4452                                 btrfs_tree_lock(next);
4453                                 if (!force_blocking)
4454                                         btrfs_clear_path_blocking(path, next);
4455                         }
4456                         if (force_blocking)
4457                                 btrfs_set_lock_blocking(next);
4458                 }
4459         }
4460         ret = 0;
4461 done:
4462         unlock_up(path, 0, 1);
4463         path->leave_spinning = old_spinning;
4464         if (!old_spinning)
4465                 btrfs_set_path_blocking(path);
4466
4467         return ret;
4468 }
4469
4470 /*
4471  * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
4472  * searching until it gets past min_objectid or finds an item of 'type'
4473  *
4474  * returns 0 if something is found, 1 if nothing was found and < 0 on error
4475  */
4476 int btrfs_previous_item(struct btrfs_root *root,
4477                         struct btrfs_path *path, u64 min_objectid,
4478                         int type)
4479 {
4480         struct btrfs_key found_key;
4481         struct extent_buffer *leaf;
4482         u32 nritems;
4483         int ret;
4484
4485         while (1) {
4486                 if (path->slots[0] == 0) {
4487                         btrfs_set_path_blocking(path);
4488                         ret = btrfs_prev_leaf(root, path);
4489                         if (ret != 0)
4490                                 return ret;
4491                 } else {
4492                         path->slots[0]--;
4493                 }
4494                 leaf = path->nodes[0];
4495                 nritems = btrfs_header_nritems(leaf);
4496                 if (nritems == 0)
4497                         return 1;
4498                 if (path->slots[0] == nritems)
4499                         path->slots[0]--;
4500
4501                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4502                 if (found_key.objectid < min_objectid)
4503                         break;
4504                 if (found_key.type == type)
4505                         return 0;
4506                 if (found_key.objectid == min_objectid &&
4507                     found_key.type < type)
4508                         break;
4509         }
4510         return 1;
4511 }