ctree.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18 #include "ctree.h"
  19 #include "disk-io.h"
  20 #include "transaction.h"
  21 #include "print-tree.h"
  22
  23 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  24                       *root, struct btrfs_path *path, int level);
  25 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  26                       *root, struct btrfs_key *ins_key,
  27                       struct btrfs_path *path, int data_size, int extend);
  28 static int push_node_left(struct btrfs_trans_handle *trans,
  29                           struct btrfs_root *root, struct extent_buffer *dst,
  30                           struct extent_buffer *src, int empty);
  31 static int balance_node_right(struct btrfs_trans_handle *trans,
  32                               struct btrfs_root *root,
  33                               struct extent_buffer *dst_buf,
  34                               struct extent_buffer *src_buf);
  35 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  36                    struct btrfs_path *path, int level, int slot);
  37
  38 inline void btrfs_init_path(struct btrfs_path *p)
  39 {
  40         memset(p, 0, sizeof(*p));
  41 }
  42
  43 struct btrfs_path *btrfs_alloc_path(void)
  44 {
  45         struct btrfs_path *path;
  46         path = kmalloc(sizeof(struct btrfs_path), GFP_NOFS);
  47         if (path) {
  48                 btrfs_init_path(path);
  49                 path->reada = 0;
  50         }
  51         return path;
  52 }
  53
  54 void btrfs_free_path(struct btrfs_path *p)
  55 {
  56         btrfs_release_path(NULL, p);
  57         kfree(p);
  58 }
  59
  60 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
  61 {
  62         int i;
  63         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  64                 if (!p->nodes[i])
  65                         continue;
  66                 free_extent_buffer(p->nodes[i]);
  67         }
  68         memset(p, 0, sizeof(*p));
  69 }
  70
  71 static void add_root_to_dirty_list(struct btrfs_root *root)
  72 {
  73         if (root->track_dirty && list_empty(&root->dirty_list)) {
  74                 list_add(&root->dirty_list,
  75                          &root->fs_info->dirty_cowonly_roots);
  76         }
  77 }
  78
  79 int btrfs_copy_root(struct btrfs_trans_handle *trans,
  80                       struct btrfs_root *root,
  81                       struct extent_buffer *buf,
  82                       struct extent_buffer **cow_ret, u64 new_root_objectid)
  83 {
  84         struct extent_buffer *cow;
  85         int ret = 0;
  86         int level;
  87         struct btrfs_root *new_root;
  88         struct btrfs_disk_key disk_key;
  89
  90         new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
  91         if (!new_root)
  92                 return -ENOMEM;
  93
  94         memcpy(new_root, root, sizeof(*new_root));
  95         new_root->root_key.objectid = new_root_objectid;
  96
  97         WARN_ON(root->ref_cows && trans->transid !=
  98                 root->fs_info->running_transaction->transid);
  99         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 100
 101         level = btrfs_header_level(buf);
 102         if (level == 0)
 103                 btrfs_item_key(buf, &disk_key, 0);
 104         else
 105                 btrfs_node_key(buf, &disk_key, 0);
 106         cow = btrfs_alloc_free_block(trans, new_root, buf->len,
 107                                      new_root_objectid, &disk_key,
 108                                      level, buf->start, 0);
 109         if (IS_ERR(cow)) {
 110                 kfree(new_root);
 111                 return PTR_ERR(cow);
 112         }
 113
 114         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 115         btrfs_set_header_bytenr(cow, cow->start);
 116         btrfs_set_header_generation(cow, trans->transid);
 117         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 118         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 119                                      BTRFS_HEADER_FLAG_RELOC);
 120         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 121                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 122         else
 123                 btrfs_set_header_owner(cow, new_root_objectid);
 124
 125         write_extent_buffer(cow, root->fs_info->fsid,
 126                             (unsigned long)btrfs_header_fsid(cow),
 127                             BTRFS_FSID_SIZE);
 128
 129         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 130         ret = btrfs_inc_ref(trans, new_root, cow, 0);
 131         kfree(new_root);
 132
 133         if (ret)
 134                 return ret;
 135
 136         btrfs_mark_buffer_dirty(cow);
 137         *cow_ret = cow;
 138         return 0;
 139 }
 140
 141 /*
 142  * check if the tree block can be shared by multiple trees
 143  */
 144 int btrfs_block_can_be_shared(struct btrfs_root *root,
 145                               struct extent_buffer *buf)
 146 {
 147         /*
 148          * Tree blocks not in refernece counted trees and tree roots
 149          * are never shared. If a block was allocated after the last
 150          * snapshot and the block was not allocated by tree relocation,
 151          * we know the block is not shared.
 152          */
 153         if (root->ref_cows &&
 154             buf != root->node && buf != root->commit_root &&
 155             (btrfs_header_generation(buf) <=
 156              btrfs_root_last_snapshot(&root->root_item) ||
 157              btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 158                 return 1;
 159 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 160         if (root->ref_cows &&
 161             btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 162                 return 1;
 163 #endif
 164         return 0;
 165 }
 166
 167 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 168                                        struct btrfs_root *root,
 169                                        struct extent_buffer *buf,
 170                                        struct extent_buffer *cow)
 171 {
 172         u64 refs;
 173         u64 owner;
 174         u64 flags;
 175         u64 new_flags = 0;
 176         int ret;
 177
 178         /*
 179          * Backrefs update rules:
 180          *
 181          * Always use full backrefs for extent pointers in tree block
 182          * allocated by tree relocation.
 183          *
 184          * If a shared tree block is no longer referenced by its owner
 185          * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 186          * use full backrefs for extent pointers in tree block.
 187          *
 188          * If a tree block is been relocating
 189          * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
 190          * use full backrefs for extent pointers in tree block.
 191          * The reason for this is some operations (such as drop tree)
 192          * are only allowed for blocks use full backrefs.
 193          */
 194
 195         if (btrfs_block_can_be_shared(root, buf)) {
 196                 ret = btrfs_lookup_extent_info(trans, root, buf->start,
 197                                                buf->len, &refs, &flags);
 198                 BUG_ON(ret);
 199                 BUG_ON(refs == 0);
 200         } else {
 201                 refs = 1;
 202                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 203                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 204                         flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
 205                 else
 206                         flags = 0;
 207         }
 208
 209         owner = btrfs_header_owner(buf);
 210         BUG_ON(!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) &&
 211                owner == BTRFS_TREE_RELOC_OBJECTID);
 212
 213         if (refs > 1) {
 214                 if ((owner == root->root_key.objectid ||
 215                      root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 216                     !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 217                         ret = btrfs_inc_ref(trans, root, buf, 1);
 218                         BUG_ON(ret);
 219
 220                         if (root->root_key.objectid ==
 221                             BTRFS_TREE_RELOC_OBJECTID) {
 222                                 ret = btrfs_dec_ref(trans, root, buf, 0);
 223                                 BUG_ON(ret);
 224                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 225                                 BUG_ON(ret);
 226                         }
 227                         new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 228                 } else {
 229
 230                         if (root->root_key.objectid ==
 231                             BTRFS_TREE_RELOC_OBJECTID)
 232                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 233                         else
 234                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 235                         BUG_ON(ret);
 236                 }
 237                 if (new_flags != 0) {
 238                         ret = btrfs_set_block_flags(trans, root, buf->start,
 239                                                     buf->len, new_flags);
 240                         BUG_ON(ret);
 241                 }
 242         } else {
 243                 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
 244                         if (root->root_key.objectid ==
 245                             BTRFS_TREE_RELOC_OBJECTID)
 246                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 247                         else
 248                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 249                         BUG_ON(ret);
 250                         ret = btrfs_dec_ref(trans, root, buf, 1);
 251                         BUG_ON(ret);
 252                 }
 253                 clean_tree_block(trans, root, buf);
 254         }
 255         return 0;
 256 }
 257
 258 int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 259                              struct btrfs_root *root,
 260                              struct extent_buffer *buf,
 261                              struct extent_buffer *parent, int parent_slot,
 262                              struct extent_buffer **cow_ret,
 263                              u64 search_start, u64 empty_size)
 264 {
 265         u64 generation;
 266         struct extent_buffer *cow;
 267         struct btrfs_disk_key disk_key;
 268         int level;
 269
 270         WARN_ON(root->ref_cows && trans->transid !=
 271                 root->fs_info->running_transaction->transid);
 272         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 273
 274         level = btrfs_header_level(buf);
 275         generation = btrfs_header_generation(buf);
 276
 277         if (level == 0)
 278                 btrfs_item_key(buf, &disk_key, 0);
 279         else
 280                 btrfs_node_key(buf, &disk_key, 0);
 281
 282         cow = btrfs_alloc_free_block(trans, root, buf->len,
 283                                      root->root_key.objectid, &disk_key,
 284                                      level, search_start, empty_size);
 285         if (IS_ERR(cow))
 286                 return PTR_ERR(cow);
 287
 288         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 289         btrfs_set_header_bytenr(cow, cow->start);
 290         btrfs_set_header_generation(cow, trans->transid);
 291         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 292         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 293                                      BTRFS_HEADER_FLAG_RELOC);
 294         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 295                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 296         else
 297                 btrfs_set_header_owner(cow, root->root_key.objectid);
 298
 299         write_extent_buffer(cow, root->fs_info->fsid,
 300                             (unsigned long)btrfs_header_fsid(cow),
 301                             BTRFS_FSID_SIZE);
 302
 303         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 304
 305         update_ref_for_cow(trans, root, buf, cow);
 306
 307         if (buf == root->node) {
 308                 root->node = cow;
 309                 extent_buffer_get(cow);
 310
 311                 btrfs_free_extent(trans, root, buf->start, buf->len,
 312                                   0, root->root_key.objectid, level, 0);
 313                 free_extent_buffer(buf);
 314                 add_root_to_dirty_list(root);
 315         } else {
 316                 btrfs_set_node_blockptr(parent, parent_slot,
 317                                         cow->start);
 318                 WARN_ON(trans->transid == 0);
 319                 btrfs_set_node_ptr_generation(parent, parent_slot,
 320                                               trans->transid);
 321                 btrfs_mark_buffer_dirty(parent);
 322                 WARN_ON(btrfs_header_generation(parent) != trans->transid);
 323
 324                 btrfs_free_extent(trans, root, buf->start, buf->len,
 325                                   0, root->root_key.objectid, level, 1);
 326         }
 327         free_extent_buffer(buf);
 328         btrfs_mark_buffer_dirty(cow);
 329         *cow_ret = cow;
 330         return 0;
 331 }
 332
 333 static inline int should_cow_block(struct btrfs_trans_handle *trans,
 334                                    struct btrfs_root *root,
 335                                    struct extent_buffer *buf)
 336 {
 337         if (btrfs_header_generation(buf) == trans->transid &&
 338             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
 339             !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
 340               btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 341                 return 0;
 342         return 1;
 343 }
 344
 345 int btrfs_cow_block(struct btrfs_trans_handle *trans,
 346                     struct btrfs_root *root, struct extent_buffer *buf,
 347                     struct extent_buffer *parent, int parent_slot,
 348                     struct extent_buffer **cow_ret)
 349 {
 350         u64 search_start;
 351         int ret;
 352         /*
 353         if (trans->transaction != root->fs_info->running_transaction) {
 354                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 355                        root->fs_info->running_transaction->transid);
 356                 WARN_ON(1);
 357         }
 358         */
 359         if (trans->transid != root->fs_info->generation) {
 360                 printk(KERN_CRIT "trans %llu running %llu\n",
 361                         (unsigned long long)trans->transid,
 362                         (unsigned long long)root->fs_info->generation);
 363                 WARN_ON(1);
 364         }
 365         if (!should_cow_block(trans, root, buf)) {
 366                 *cow_ret = buf;
 367                 return 0;
 368         }
 369
 370         search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
 371         ret = __btrfs_cow_block(trans, root, buf, parent,
 372                                  parent_slot, cow_ret, search_start, 0);
 373         return ret;
 374 }
 375
 376 /*
 377 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 378 {
 379         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 380                 return 1;
 381         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 382                 return 1;
 383         return 0;
 384 }
 385 */
 386
 387 /*
 388  * compare two keys in a memcmp fashion
 389  */
 390 int btrfs_comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 391 {
 392         struct btrfs_key k1;
 393
 394         btrfs_disk_key_to_cpu(&k1, disk);
 395
 396         if (k1.objectid > k2->objectid)
 397                 return 1;
 398         if (k1.objectid < k2->objectid)
 399                 return -1;
 400         if (k1.type > k2->type)
 401                 return 1;
 402         if (k1.type < k2->type)
 403                 return -1;
 404         if (k1.offset > k2->offset)
 405                 return 1;
 406         if (k1.offset < k2->offset)
 407                 return -1;
 408         return 0;
 409 }
 410
 411
 412 #if 0
 413 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 414                        struct btrfs_root *root, struct extent_buffer *parent,
 415                        int start_slot, int cache_only, u64 *last_ret,
 416                        struct btrfs_key *progress)
 417 {
 418         struct extent_buffer *cur;
 419         struct extent_buffer *tmp;
 420         u64 blocknr;
 421         u64 gen;
 422         u64 search_start = *last_ret;
 423         u64 last_block = 0;
 424         u64 other;
 425         u32 parent_nritems;
 426         int end_slot;
 427         int i;
 428         int err = 0;
 429         int parent_level;
 430         int uptodate;
 431         u32 blocksize;
 432         int progress_passed = 0;
 433         struct btrfs_disk_key disk_key;
 434
 435         parent_level = btrfs_header_level(parent);
 436         if (cache_only && parent_level != 1)
 437                 return 0;
 438
 439         if (trans->transaction != root->fs_info->running_transaction) {
 440                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 441                        root->fs_info->running_transaction->transid);
 442                 WARN_ON(1);
 443         }
 444         if (trans->transid != root->fs_info->generation) {
 445                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 446                        root->fs_info->generation);
 447                 WARN_ON(1);
 448         }
 449
 450         parent_nritems = btrfs_header_nritems(parent);
 451         blocksize = btrfs_level_size(root, parent_level - 1);
 452         end_slot = parent_nritems;
 453
 454         if (parent_nritems == 1)
 455                 return 0;
 456
 457         for (i = start_slot; i < end_slot; i++) {
 458                 int close = 1;
 459
 460                 if (!parent->map_token) {
 461                         map_extent_buffer(parent,
 462                                         btrfs_node_key_ptr_offset(i),
 463                                         sizeof(struct btrfs_key_ptr),
 464                                         &parent->map_token, &parent->kaddr,
 465                                         &parent->map_start, &parent->map_len,
 466                                         KM_USER1);
 467                 }
 468                 btrfs_node_key(parent, &disk_key, i);
 469                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
 470                         continue;
 471
 472                 progress_passed = 1;
 473                 blocknr = btrfs_node_blockptr(parent, i);
 474                 gen = btrfs_node_ptr_generation(parent, i);
 475                 if (last_block == 0)
 476                         last_block = blocknr;
 477
 478                 if (i > 0) {
 479                         other = btrfs_node_blockptr(parent, i - 1);
 480                         close = close_blocks(blocknr, other, blocksize);
 481                 }
 482                 if (close && i < end_slot - 2) {
 483                         other = btrfs_node_blockptr(parent, i + 1);
 484                         close = close_blocks(blocknr, other, blocksize);
 485                 }
 486                 if (close) {
 487                         last_block = blocknr;
 488                         continue;
 489                 }
 490                 if (parent->map_token) {
 491                         unmap_extent_buffer(parent, parent->map_token,
 492                                             KM_USER1);
 493                         parent->map_token = NULL;
 494                 }
 495
 496                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
 497                 if (cur)
 498                         uptodate = btrfs_buffer_uptodate(cur, gen);
 499                 else
 500                         uptodate = 0;
 501                 if (!cur || !uptodate) {
 502                         if (cache_only) {
 503                                 free_extent_buffer(cur);
 504                                 continue;
 505                         }
 506                         if (!cur) {
 507                                 cur = read_tree_block(root, blocknr,
 508                                                          blocksize, gen);
 509                         } else if (!uptodate) {
 510                                 btrfs_read_buffer(cur, gen);
 511                         }
 512                 }
 513                 if (search_start == 0)
 514                         search_start = last_block;
 515
 516                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 517                                         &tmp, search_start,
 518                                         min(16 * blocksize,
 519                                             (end_slot - i) * blocksize));
 520                 if (err) {
 521                         free_extent_buffer(cur);
 522                         break;
 523                 }
 524                 search_start = tmp->start;
 525                 last_block = tmp->start;
 526                 *last_ret = search_start;
 527                 if (parent_level == 1)
 528                         btrfs_clear_buffer_defrag(tmp);
 529                 free_extent_buffer(tmp);
 530         }
 531         if (parent->map_token) {
 532                 unmap_extent_buffer(parent, parent->map_token,
 533                                     KM_USER1);
 534                 parent->map_token = NULL;
 535         }
 536         return err;
 537 }
 538 #endif
 539
 540 /*
 541  * The leaf data grows from end-to-front in the node.
 542  * this returns the address of the start of the last item,
 543  * which is the stop of the leaf data stack
 544  */
 545 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 546                                          struct extent_buffer *leaf)
 547 {
 548         u32 nr = btrfs_header_nritems(leaf);
 549         if (nr == 0)
 550                 return BTRFS_LEAF_DATA_SIZE(root);
 551         return btrfs_item_offset_nr(leaf, nr - 1);
 552 }
 553
 554 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 555                       int level)
 556 {
 557         struct extent_buffer *parent = NULL;
 558         struct extent_buffer *node = path->nodes[level];
 559         struct btrfs_disk_key parent_key;
 560         struct btrfs_disk_key node_key;
 561         int parent_slot;
 562         int slot;
 563         struct btrfs_key cpukey;
 564         u32 nritems = btrfs_header_nritems(node);
 565
 566         if (path->nodes[level + 1])
 567                 parent = path->nodes[level + 1];
 568
 569         slot = path->slots[level];
 570         BUG_ON(nritems == 0);
 571         if (parent) {
 572                 parent_slot = path->slots[level + 1];
 573                 btrfs_node_key(parent, &parent_key, parent_slot);
 574                 btrfs_node_key(node, &node_key, 0);
 575                 BUG_ON(memcmp(&parent_key, &node_key,
 576                               sizeof(struct btrfs_disk_key)));
 577                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 578                        btrfs_header_bytenr(node));
 579         }
 580         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 581         if (slot != 0) {
 582                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 583                 btrfs_node_key(node, &node_key, slot);
 584                 BUG_ON(btrfs_comp_keys(&node_key, &cpukey) <= 0);
 585         }
 586         if (slot < nritems - 1) {
 587                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 588                 btrfs_node_key(node, &node_key, slot);
 589                 BUG_ON(btrfs_comp_keys(&node_key, &cpukey) >= 0);
 590         }
 591         return 0;
 592 }
 593
 594 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 595                       int level)
 596 {
 597         struct extent_buffer *leaf = path->nodes[level];
 598         struct extent_buffer *parent = NULL;
 599         int parent_slot;
 600         struct btrfs_key cpukey;
 601         struct btrfs_disk_key parent_key;
 602         struct btrfs_disk_key leaf_key;
 603         int slot = path->slots[0];
 604
 605         u32 nritems = btrfs_header_nritems(leaf);
 606
 607         if (path->nodes[level + 1])
 608                 parent = path->nodes[level + 1];
 609
 610         if (nritems == 0)
 611                 return 0;
 612
 613         if (parent) {
 614                 parent_slot = path->slots[level + 1];
 615                 btrfs_node_key(parent, &parent_key, parent_slot);
 616                 btrfs_item_key(leaf, &leaf_key, 0);
 617
 618                 BUG_ON(memcmp(&parent_key, &leaf_key,
 619                        sizeof(struct btrfs_disk_key)));
 620                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 621                        btrfs_header_bytenr(leaf));
 622         }
 623 #if 0
 624         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 625                 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
 626                 btrfs_item_key(leaf, &leaf_key, i);
 627                 if (comp_keys(&leaf_key, &cpukey) >= 0) {
 628                         btrfs_print_leaf(root, leaf);
 629                         printk("slot %d offset bad key\n", i);
 630                         BUG_ON(1);
 631                 }
 632                 if (btrfs_item_offset_nr(leaf, i) !=
 633                         btrfs_item_end_nr(leaf, i + 1)) {
 634                         btrfs_print_leaf(root, leaf);
 635                         printk("slot %d offset bad\n", i);
 636                         BUG_ON(1);
 637                 }
 638                 if (i == 0) {
 639                         if (btrfs_item_offset_nr(leaf, i) +
 640                                btrfs_item_size_nr(leaf, i) !=
 641                                BTRFS_LEAF_DATA_SIZE(root)) {
 642                                 btrfs_print_leaf(root, leaf);
 643                                 printk("slot %d first offset bad\n", i);
 644                                 BUG_ON(1);
 645                         }
 646                 }
 647         }
 648         if (nritems > 0) {
 649                 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
 650                                 btrfs_print_leaf(root, leaf);
 651                                 printk("slot %d bad size \n", nritems - 1);
 652                                 BUG_ON(1);
 653                 }
 654         }
 655 #endif
 656         if (slot != 0 && slot < nritems - 1) {
 657                 btrfs_item_key(leaf, &leaf_key, slot);
 658                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 659                 if (btrfs_comp_keys(&leaf_key, &cpukey) <= 0) {
 660                         btrfs_print_leaf(root, leaf);
 661                         printk("slot %d offset bad key\n", slot);
 662                         BUG_ON(1);
 663                 }
 664                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 665                        btrfs_item_end_nr(leaf, slot)) {
 666                         btrfs_print_leaf(root, leaf);
 667                         printk("slot %d offset bad\n", slot);
 668                         BUG_ON(1);
 669                 }
 670         }
 671         if (slot < nritems - 1) {
 672                 btrfs_item_key(leaf, &leaf_key, slot);
 673                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 674                 BUG_ON(btrfs_comp_keys(&leaf_key, &cpukey) >= 0);
 675                 if (btrfs_item_offset_nr(leaf, slot) !=
 676                         btrfs_item_end_nr(leaf, slot + 1)) {
 677                         btrfs_print_leaf(root, leaf);
 678                         printk("slot %d offset bad\n", slot);
 679                         BUG_ON(1);
 680                 }
 681         }
 682         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 683                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 684         return 0;
 685 }
 686
 687 static int noinline check_block(struct btrfs_root *root,
 688                                 struct btrfs_path *path, int level)
 689 {
 690         return 0;
 691 #if 0
 692         struct extent_buffer *buf = path->nodes[level];
 693
 694         if (memcmp_extent_buffer(buf, root->fs_info->fsid,
 695                                  (unsigned long)btrfs_header_fsid(buf),
 696                                  BTRFS_FSID_SIZE)) {
 697                 printk("warning bad block %Lu\n", buf->start);
 698                 return 1;
 699         }
 700 #endif
 701         if (level == 0)
 702                 return check_leaf(root, path, level);
 703         return check_node(root, path, level);
 704 }
 705
 706 /*
 707  * search for key in the extent_buffer.  The items start at offset p,
 708  * and they are item_size apart.  There are 'max' items in p.
 709  *
 710  * the slot in the array is returned via slot, and it points to
 711  * the place where you would insert key if it is not found in
 712  * the array.
 713  *
 714  * slot may point to max if the key is bigger than all of the keys
 715  */
 716 static int generic_bin_search(struct extent_buffer *eb, unsigned long p,
 717                               int item_size, struct btrfs_key *key,
 718                               int max, int *slot)
 719 {
 720         int low = 0;
 721         int high = max;
 722         int mid;
 723         int ret;
 724         unsigned long offset;
 725         struct btrfs_disk_key *tmp;
 726
 727         while(low < high) {
 728                 mid = (low + high) / 2;
 729                 offset = p + mid * item_size;
 730
 731                 tmp = (struct btrfs_disk_key *)(eb->data + offset);
 732                 ret = btrfs_comp_keys(tmp, key);
 733
 734                 if (ret < 0)
 735                         low = mid + 1;
 736                 else if (ret > 0)
 737                         high = mid;
 738                 else {
 739                         *slot = mid;
 740                         return 0;
 741                 }
 742         }
 743         *slot = low;
 744         return 1;
 745 }
 746
 747 /*
 748  * simple bin_search frontend that does the right thing for
 749  * leaves vs nodes
 750  */
 751 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 752                       int level, int *slot)
 753 {
 754         if (level == 0) {
 755                 return generic_bin_search(eb,
 756                                           offsetof(struct btrfs_leaf, items),
 757                                           sizeof(struct btrfs_item),
 758                                           key, btrfs_header_nritems(eb),
 759                                           slot);
 760         } else {
 761                 return generic_bin_search(eb,
 762                                           offsetof(struct btrfs_node, ptrs),
 763                                           sizeof(struct btrfs_key_ptr),
 764                                           key, btrfs_header_nritems(eb),
 765                                           slot);
 766         }
 767         return -1;
 768 }
 769
 770 static struct extent_buffer *read_node_slot(struct btrfs_root *root,
 771                                    struct extent_buffer *parent, int slot)
 772 {
 773         int level = btrfs_header_level(parent);
 774         if (slot < 0)
 775                 return NULL;
 776         if (slot >= btrfs_header_nritems(parent))
 777                 return NULL;
 778
 779         BUG_ON(level == 0);
 780
 781         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 782                        btrfs_level_size(root, level - 1),
 783                        btrfs_node_ptr_generation(parent, slot));
 784 }
 785
 786 static int balance_level(struct btrfs_trans_handle *trans,
 787                          struct btrfs_root *root,
 788                          struct btrfs_path *path, int level)
 789 {
 790         struct extent_buffer *right = NULL;
 791         struct extent_buffer *mid;
 792         struct extent_buffer *left = NULL;
 793         struct extent_buffer *parent = NULL;
 794         int ret = 0;
 795         int wret;
 796         int pslot;
 797         int orig_slot = path->slots[level];
 798         int err_on_enospc = 0;
 799         u64 orig_ptr;
 800
 801         if (level == 0)
 802                 return 0;
 803
 804         mid = path->nodes[level];
 805         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 806
 807         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 808
 809         if (level < BTRFS_MAX_LEVEL - 1)
 810                 parent = path->nodes[level + 1];
 811         pslot = path->slots[level + 1];
 812
 813         /*
 814          * deal with the case where there is only one pointer in the root
 815          * by promoting the node below to a root
 816          */
 817         if (!parent) {
 818                 struct extent_buffer *child;
 819
 820                 if (btrfs_header_nritems(mid) != 1)
 821                         return 0;
 822
 823                 /* promote the child to a root */
 824                 child = read_node_slot(root, mid, 0);
 825                 BUG_ON(!child);
 826                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
 827                 BUG_ON(ret);
 828
 829                 root->node = child;
 830                 add_root_to_dirty_list(root);
 831                 path->nodes[level] = NULL;
 832                 clean_tree_block(trans, root, mid);
 833                 wait_on_tree_block_writeback(root, mid);
 834                 /* once for the path */
 835                 free_extent_buffer(mid);
 836
 837                 ret = btrfs_free_extent(trans, root, mid->start, mid->len,
 838                                         0, root->root_key.objectid,
 839                                         level, 1);
 840                 /* once for the root ptr */
 841                 free_extent_buffer(mid);
 842                 return ret;
 843         }
 844         if (btrfs_header_nritems(mid) >
 845             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 846                 return 0;
 847
 848         if (btrfs_header_nritems(mid) < 2)
 849                 err_on_enospc = 1;
 850
 851         left = read_node_slot(root, parent, pslot - 1);
 852         if (left) {
 853                 wret = btrfs_cow_block(trans, root, left,
 854                                        parent, pslot - 1, &left);
 855                 if (wret) {
 856                         ret = wret;
 857                         goto enospc;
 858                 }
 859         }
 860         right = read_node_slot(root, parent, pslot + 1);
 861         if (right) {
 862                 wret = btrfs_cow_block(trans, root, right,
 863                                        parent, pslot + 1, &right);
 864                 if (wret) {
 865                         ret = wret;
 866                         goto enospc;
 867                 }
 868         }
 869
 870         /* first, try to make some room in the middle buffer */
 871         if (left) {
 872                 orig_slot += btrfs_header_nritems(left);
 873                 wret = push_node_left(trans, root, left, mid, 1);
 874                 if (wret < 0)
 875                         ret = wret;
 876                 if (btrfs_header_nritems(mid) < 2)
 877                         err_on_enospc = 1;
 878         }
 879
 880         /*
 881          * then try to empty the right most buffer into the middle
 882          */
 883         if (right) {
 884                 wret = push_node_left(trans, root, mid, right, 1);
 885                 if (wret < 0 && wret != -ENOSPC)
 886                         ret = wret;
 887                 if (btrfs_header_nritems(right) == 0) {
 888                         u64 bytenr = right->start;
 889                         u32 blocksize = right->len;
 890
 891                         clean_tree_block(trans, root, right);
 892                         wait_on_tree_block_writeback(root, right);
 893                         free_extent_buffer(right);
 894                         right = NULL;
 895                         wret = del_ptr(trans, root, path, level + 1, pslot +
 896                                        1);
 897                         if (wret)
 898                                 ret = wret;
 899                         wret = btrfs_free_extent(trans, root, bytenr,
 900                                                  blocksize, 0,
 901                                                  root->root_key.objectid,
 902                                                  level, 0);
 903                         if (wret)
 904                                 ret = wret;
 905                 } else {
 906                         struct btrfs_disk_key right_key;
 907                         btrfs_node_key(right, &right_key, 0);
 908                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 909                         btrfs_mark_buffer_dirty(parent);
 910                 }
 911         }
 912         if (btrfs_header_nritems(mid) == 1) {
 913                 /*
 914                  * we're not allowed to leave a node with one item in the
 915                  * tree during a delete.  A deletion from lower in the tree
 916                  * could try to delete the only pointer in this node.
 917                  * So, pull some keys from the left.
 918                  * There has to be a left pointer at this point because
 919                  * otherwise we would have pulled some pointers from the
 920                  * right
 921                  */
 922                 BUG_ON(!left);
 923                 wret = balance_node_right(trans, root, mid, left);
 924                 if (wret < 0) {
 925                         ret = wret;
 926                         goto enospc;
 927                 }
 928                 if (wret == 1) {
 929                         wret = push_node_left(trans, root, left, mid, 1);
 930                         if (wret < 0)
 931                                 ret = wret;
 932                 }
 933                 BUG_ON(wret == 1);
 934         }
 935         if (btrfs_header_nritems(mid) == 0) {
 936                 /* we've managed to empty the middle node, drop it */
 937                 u64 bytenr = mid->start;
 938                 u32 blocksize = mid->len;
 939                 clean_tree_block(trans, root, mid);
 940                 wait_on_tree_block_writeback(root, mid);
 941                 free_extent_buffer(mid);
 942                 mid = NULL;
 943                 wret = del_ptr(trans, root, path, level + 1, pslot);
 944                 if (wret)
 945                         ret = wret;
 946                 wret = btrfs_free_extent(trans, root, bytenr, blocksize,
 947                                          0, root->root_key.objectid,
 948                                          level, 0);
 949                 if (wret)
 950                         ret = wret;
 951         } else {
 952                 /* update the parent key to reflect our changes */
 953                 struct btrfs_disk_key mid_key;
 954                 btrfs_node_key(mid, &mid_key, 0);
 955                 btrfs_set_node_key(parent, &mid_key, pslot);
 956                 btrfs_mark_buffer_dirty(parent);
 957         }
 958
 959         /* update the path */
 960         if (left) {
 961                 if (btrfs_header_nritems(left) > orig_slot) {
 962                         extent_buffer_get(left);
 963                         path->nodes[level] = left;
 964                         path->slots[level + 1] -= 1;
 965                         path->slots[level] = orig_slot;
 966                         if (mid)
 967                                 free_extent_buffer(mid);
 968                 } else {
 969                         orig_slot -= btrfs_header_nritems(left);
 970                         path->slots[level] = orig_slot;
 971                 }
 972         }
 973         /* double check we haven't messed things up */
 974         check_block(root, path, level);
 975         if (orig_ptr !=
 976             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 977                 BUG();
 978 enospc:
 979         if (right)
 980                 free_extent_buffer(right);
 981         if (left)
 982                 free_extent_buffer(left);
 983         return ret;
 984 }
 985
 986 /* returns zero if the push worked, non-zero otherwise */
 987 static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
 988                                           struct btrfs_root *root,
 989                                           struct btrfs_path *path, int level)
 990 {
 991         struct extent_buffer *right = NULL;
 992         struct extent_buffer *mid;
 993         struct extent_buffer *left = NULL;
 994         struct extent_buffer *parent = NULL;
 995         int ret = 0;
 996         int wret;
 997         int pslot;
 998         int orig_slot = path->slots[level];
 999         u64 orig_ptr;
1000
1001         if (level == 0)
1002                 return 1;
1003
1004         mid = path->nodes[level];
1005         WARN_ON(btrfs_header_generation(mid) != trans->transid);
1006         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1007
1008         if (level < BTRFS_MAX_LEVEL - 1)
1009                 parent = path->nodes[level + 1];
1010         pslot = path->slots[level + 1];
1011
1012         if (!parent)
1013                 return 1;
1014
1015         left = read_node_slot(root, parent, pslot - 1);
1016
1017         /* first, try to make some room in the middle buffer */
1018         if (left) {
1019                 u32 left_nr;
1020                 left_nr = btrfs_header_nritems(left);
1021                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1022                         wret = 1;
1023                 } else {
1024                         ret = btrfs_cow_block(trans, root, left, parent,
1025                                               pslot - 1, &left);
1026                         if (ret)
1027                                 wret = 1;
1028                         else {
1029                                 wret = push_node_left(trans, root,
1030                                                       left, mid, 0);
1031                         }
1032                 }
1033                 if (wret < 0)
1034                         ret = wret;
1035                 if (wret == 0) {
1036                         struct btrfs_disk_key disk_key;
1037                         orig_slot += left_nr;
1038                         btrfs_node_key(mid, &disk_key, 0);
1039                         btrfs_set_node_key(parent, &disk_key, pslot);
1040                         btrfs_mark_buffer_dirty(parent);
1041                         if (btrfs_header_nritems(left) > orig_slot) {
1042                                 path->nodes[level] = left;
1043                                 path->slots[level + 1] -= 1;
1044                                 path->slots[level] = orig_slot;
1045                                 free_extent_buffer(mid);
1046                         } else {
1047                                 orig_slot -=
1048                                         btrfs_header_nritems(left);
1049                                 path->slots[level] = orig_slot;
1050                                 free_extent_buffer(left);
1051                         }
1052                         return 0;
1053                 }
1054                 free_extent_buffer(left);
1055         }
1056         right= read_node_slot(root, parent, pslot + 1);
1057
1058         /*
1059          * then try to empty the right most buffer into the middle
1060          */
1061         if (right) {
1062                 u32 right_nr;
1063                 right_nr = btrfs_header_nritems(right);
1064                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1065                         wret = 1;
1066                 } else {
1067                         ret = btrfs_cow_block(trans, root, right,
1068                                               parent, pslot + 1,
1069                                               &right);
1070                         if (ret)
1071                                 wret = 1;
1072                         else {
1073                                 wret = balance_node_right(trans, root,
1074                                                           right, mid);
1075                         }
1076                 }
1077                 if (wret < 0)
1078                         ret = wret;
1079                 if (wret == 0) {
1080                         struct btrfs_disk_key disk_key;
1081
1082                         btrfs_node_key(right, &disk_key, 0);
1083                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
1084                         btrfs_mark_buffer_dirty(parent);
1085
1086                         if (btrfs_header_nritems(mid) <= orig_slot) {
1087                                 path->nodes[level] = right;
1088                                 path->slots[level + 1] += 1;
1089                                 path->slots[level] = orig_slot -
1090                                         btrfs_header_nritems(mid);
1091                                 free_extent_buffer(mid);
1092                         } else {
1093                                 free_extent_buffer(right);
1094                         }
1095                         return 0;
1096                 }
1097                 free_extent_buffer(right);
1098         }
1099         return 1;
1100 }
1101
1102 /*
1103  * readahead one full node of leaves
1104  */
1105 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
1106                              int level, int slot, u64 objectid)
1107 {
1108         struct extent_buffer *node;
1109         struct btrfs_disk_key disk_key;
1110         u32 nritems;
1111         u64 search;
1112         u64 lowest_read;
1113         u64 highest_read;
1114         u64 nread = 0;
1115         int direction = path->reada;
1116         struct extent_buffer *eb;
1117         u32 nr;
1118         u32 blocksize;
1119         u32 nscan = 0;
1120
1121         if (level != 1)
1122                 return;
1123
1124         if (!path->nodes[level])
1125                 return;
1126
1127         node = path->nodes[level];
1128         search = btrfs_node_blockptr(node, slot);
1129         blocksize = btrfs_level_size(root, level - 1);
1130         eb = btrfs_find_tree_block(root, search, blocksize);
1131         if (eb) {
1132                 free_extent_buffer(eb);
1133                 return;
1134         }
1135
1136         highest_read = search;
1137         lowest_read = search;
1138
1139         nritems = btrfs_header_nritems(node);
1140         nr = slot;
1141         while(1) {
1142                 if (direction < 0) {
1143                         if (nr == 0)
1144                                 break;
1145                         nr--;
1146                 } else if (direction > 0) {
1147                         nr++;
1148                         if (nr >= nritems)
1149                                 break;
1150                 }
1151                 if (path->reada < 0 && objectid) {
1152                         btrfs_node_key(node, &disk_key, nr);
1153                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1154                                 break;
1155                 }
1156                 search = btrfs_node_blockptr(node, nr);
1157                 if ((search >= lowest_read && search <= highest_read) ||
1158                     (search < lowest_read && lowest_read - search <= 32768) ||
1159                     (search > highest_read && search - highest_read <= 32768)) {
1160                         readahead_tree_block(root, search, blocksize,
1161                                      btrfs_node_ptr_generation(node, nr));
1162                         nread += blocksize;
1163                 }
1164                 nscan++;
1165                 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
1166                         break;
1167                 if(nread > (1024 * 1024) || nscan > 128)
1168                         break;
1169
1170                 if (search < lowest_read)
1171                         lowest_read = search;
1172                 if (search > highest_read)
1173                         highest_read = search;
1174         }
1175 }
1176
1177 /*
1178  * look for key in the tree.  path is filled in with nodes along the way
1179  * if key is found, we return zero and you can find the item in the leaf
1180  * level of the path (level 0)
1181  *
1182  * If the key isn't found, the path points to the slot where it should
1183  * be inserted, and 1 is returned.  If there are other errors during the
1184  * search a negative error number is returned.
1185  *
1186  * if ins_len > 0, nodes and leaves will be split as we walk down the
1187  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
1188  * possible)
1189  */
1190 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1191                       *root, struct btrfs_key *key, struct btrfs_path *p, int
1192                       ins_len, int cow)
1193 {
1194         struct extent_buffer *b;
1195         int slot;
1196         int ret;
1197         int level;
1198         int should_reada = p->reada;
1199         u8 lowest_level = 0;
1200
1201         lowest_level = p->lowest_level;
1202         WARN_ON(lowest_level && ins_len);
1203         WARN_ON(p->nodes[0] != NULL);
1204         /*
1205         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
1206         */
1207 again:
1208         b = root->node;
1209         extent_buffer_get(b);
1210         while (b) {
1211                 level = btrfs_header_level(b);
1212                 if (cow) {
1213                         int wret;
1214                         wret = btrfs_cow_block(trans, root, b,
1215                                                p->nodes[level + 1],
1216                                                p->slots[level + 1],
1217                                                &b);
1218                         if (wret) {
1219                                 free_extent_buffer(b);
1220                                 return wret;
1221                         }
1222                 }
1223                 BUG_ON(!cow && ins_len);
1224                 if (level != btrfs_header_level(b))
1225                         WARN_ON(1);
1226                 level = btrfs_header_level(b);
1227                 p->nodes[level] = b;
1228                 ret = check_block(root, p, level);
1229                 if (ret)
1230                         return -1;
1231                 ret = bin_search(b, key, level, &slot);
1232                 if (level != 0) {
1233                         if (ret && slot > 0)
1234                                 slot -= 1;
1235                         p->slots[level] = slot;
1236                         if ((p->search_for_split || ins_len > 0) &&
1237                             btrfs_header_nritems(b) >=
1238                             BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
1239                                 int sret = split_node(trans, root, p, level);
1240                                 BUG_ON(sret > 0);
1241                                 if (sret)
1242                                         return sret;
1243                                 b = p->nodes[level];
1244                                 slot = p->slots[level];
1245                         } else if (ins_len < 0) {
1246                                 int sret = balance_level(trans, root, p,
1247                                                          level);
1248                                 if (sret)
1249                                         return sret;
1250                                 b = p->nodes[level];
1251                                 if (!b) {
1252                                         btrfs_release_path(NULL, p);
1253                                         goto again;
1254                                 }
1255                                 slot = p->slots[level];
1256                                 BUG_ON(btrfs_header_nritems(b) == 1);
1257                         }
1258                         /* this is only true while dropping a snapshot */
1259                         if (level == lowest_level)
1260                                 break;
1261
1262                         if (should_reada)
1263                                 reada_for_search(root, p, level, slot,
1264                                                  key->objectid);
1265
1266                         b = read_node_slot(root, b, slot);
1267                 } else {
1268                         p->slots[level] = slot;
1269                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1270                             sizeof(struct btrfs_item) + ins_len) {
1271                                 int sret = split_leaf(trans, root, key,
1272                                                       p, ins_len, ret == 0);
1273                                 BUG_ON(sret > 0);
1274                                 if (sret)
1275                                         return sret;
1276                         }
1277                         return ret;
1278                 }
1279         }
1280         return 1;
1281 }
1282
1283 /*
1284  * adjust the pointers going up the tree, starting at level
1285  * making sure the right key of each node is points to 'key'.
1286  * This is used after shifting pointers to the left, so it stops
1287  * fixing up pointers when a given leaf/node is not in slot 0 of the
1288  * higher levels
1289  *
1290  * If this fails to write a tree block, it returns -1, but continues
1291  * fixing up the blocks in ram so the tree is consistent.
1292  */
1293 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1294                           struct btrfs_root *root, struct btrfs_path *path,
1295                           struct btrfs_disk_key *key, int level)
1296 {
1297         int i;
1298         int ret = 0;
1299         struct extent_buffer *t;
1300
1301         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1302                 int tslot = path->slots[i];
1303                 if (!path->nodes[i])
1304                         break;
1305                 t = path->nodes[i];
1306                 btrfs_set_node_key(t, key, tslot);
1307                 btrfs_mark_buffer_dirty(path->nodes[i]);
1308                 if (tslot != 0)
1309                         break;
1310         }
1311         return ret;
1312 }
1313
1314 /*
1315  * update item key.
1316  *
1317  * This function isn't completely safe. It's the caller's responsibility
1318  * that the new key won't break the order
1319  */
1320 int btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
1321                             struct btrfs_root *root, struct btrfs_path *path,
1322                             struct btrfs_key *new_key)
1323 {
1324         struct btrfs_disk_key disk_key;
1325         struct extent_buffer *eb;
1326         int slot;
1327
1328         eb = path->nodes[0];
1329         slot = path->slots[0];
1330         if (slot > 0) {
1331                 btrfs_item_key(eb, &disk_key, slot - 1);
1332                 if (btrfs_comp_keys(&disk_key, new_key) >= 0)
1333                         return -1;
1334         }
1335         if (slot < btrfs_header_nritems(eb) - 1) {
1336                 btrfs_item_key(eb, &disk_key, slot + 1);
1337                 if (btrfs_comp_keys(&disk_key, new_key) <= 0)
1338                         return -1;
1339         }
1340
1341         btrfs_cpu_key_to_disk(&disk_key, new_key);
1342         btrfs_set_item_key(eb, &disk_key, slot);
1343         btrfs_mark_buffer_dirty(eb);
1344         if (slot == 0)
1345                 fixup_low_keys(trans, root, path, &disk_key, 1);
1346         return 0;
1347 }
1348
1349 /*
1350  * try to push data from one node into the next node left in the
1351  * tree.
1352  *
1353  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1354  * error, and > 0 if there was no room in the left hand block.
1355  */
1356 static int push_node_left(struct btrfs_trans_handle *trans,
1357                           struct btrfs_root *root, struct extent_buffer *dst,
1358                           struct extent_buffer *src, int empty)
1359 {
1360         int push_items = 0;
1361         int src_nritems;
1362         int dst_nritems;
1363         int ret = 0;
1364
1365         src_nritems = btrfs_header_nritems(src);
1366         dst_nritems = btrfs_header_nritems(dst);
1367         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1368         WARN_ON(btrfs_header_generation(src) != trans->transid);
1369         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1370
1371         if (!empty && src_nritems <= 8)
1372                 return 1;
1373
1374         if (push_items <= 0) {
1375                 return 1;
1376         }
1377
1378         if (empty) {
1379                 push_items = min(src_nritems, push_items);
1380                 if (push_items < src_nritems) {
1381                         /* leave at least 8 pointers in the node if
1382                          * we aren't going to empty it
1383                          */
1384                         if (src_nritems - push_items < 8) {
1385                                 if (push_items <= 8)
1386                                         return 1;
1387                                 push_items -= 8;
1388                         }
1389                 }
1390         } else
1391                 push_items = min(src_nritems - 8, push_items);
1392
1393         copy_extent_buffer(dst, src,
1394                            btrfs_node_key_ptr_offset(dst_nritems),
1395                            btrfs_node_key_ptr_offset(0),
1396                            push_items * sizeof(struct btrfs_key_ptr));
1397
1398         if (push_items < src_nritems) {
1399                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1400                                       btrfs_node_key_ptr_offset(push_items),
1401                                       (src_nritems - push_items) *
1402                                       sizeof(struct btrfs_key_ptr));
1403         }
1404         btrfs_set_header_nritems(src, src_nritems - push_items);
1405         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1406         btrfs_mark_buffer_dirty(src);
1407         btrfs_mark_buffer_dirty(dst);
1408
1409         return ret;
1410 }
1411
1412 /*
1413  * try to push data from one node into the next node right in the
1414  * tree.
1415  *
1416  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1417  * error, and > 0 if there was no room in the right hand block.
1418  *
1419  * this will  only push up to 1/2 the contents of the left node over
1420  */
1421 static int balance_node_right(struct btrfs_trans_handle *trans,
1422                               struct btrfs_root *root,
1423                               struct extent_buffer *dst,
1424                               struct extent_buffer *src)
1425 {
1426         int push_items = 0;
1427         int max_push;
1428         int src_nritems;
1429         int dst_nritems;
1430         int ret = 0;
1431
1432         WARN_ON(btrfs_header_generation(src) != trans->transid);
1433         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1434
1435         src_nritems = btrfs_header_nritems(src);
1436         dst_nritems = btrfs_header_nritems(dst);
1437         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1438         if (push_items <= 0) {
1439                 return 1;
1440         }
1441
1442         if (src_nritems < 4) {
1443                 return 1;
1444         }
1445
1446         max_push = src_nritems / 2 + 1;
1447         /* don't try to empty the node */
1448         if (max_push >= src_nritems) {
1449                 return 1;
1450         }
1451
1452         if (max_push < push_items)
1453                 push_items = max_push;
1454
1455         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1456                                       btrfs_node_key_ptr_offset(0),
1457                                       (dst_nritems) *
1458                                       sizeof(struct btrfs_key_ptr));
1459
1460         copy_extent_buffer(dst, src,
1461                            btrfs_node_key_ptr_offset(0),
1462                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1463                            push_items * sizeof(struct btrfs_key_ptr));
1464
1465         btrfs_set_header_nritems(src, src_nritems - push_items);
1466         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1467
1468         btrfs_mark_buffer_dirty(src);
1469         btrfs_mark_buffer_dirty(dst);
1470
1471         return ret;
1472 }
1473
1474 /*
1475  * helper function to insert a new root level in the tree.
1476  * A new node is allocated, and a single item is inserted to
1477  * point to the existing root
1478  *
1479  * returns zero on success or < 0 on failure.
1480  */
1481 static int noinline insert_new_root(struct btrfs_trans_handle *trans,
1482                            struct btrfs_root *root,
1483                            struct btrfs_path *path, int level)
1484 {
1485         u64 lower_gen;
1486         struct extent_buffer *lower;
1487         struct extent_buffer *c;
1488         struct extent_buffer *old;
1489         struct btrfs_disk_key lower_key;
1490
1491         BUG_ON(path->nodes[level]);
1492         BUG_ON(path->nodes[level-1] != root->node);
1493
1494         lower = path->nodes[level-1];
1495         if (level == 1)
1496                 btrfs_item_key(lower, &lower_key, 0);
1497         else
1498                 btrfs_node_key(lower, &lower_key, 0);
1499
1500         c = btrfs_alloc_free_block(trans, root, root->nodesize,
1501                                    root->root_key.objectid, &lower_key,
1502                                    level, root->node->start, 0);
1503
1504         if (IS_ERR(c))
1505                 return PTR_ERR(c);
1506
1507         memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
1508         btrfs_set_header_nritems(c, 1);
1509         btrfs_set_header_level(c, level);
1510         btrfs_set_header_bytenr(c, c->start);
1511         btrfs_set_header_generation(c, trans->transid);
1512         btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
1513         btrfs_set_header_owner(c, root->root_key.objectid);
1514
1515         write_extent_buffer(c, root->fs_info->fsid,
1516                             (unsigned long)btrfs_header_fsid(c),
1517                             BTRFS_FSID_SIZE);
1518
1519         write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
1520                             (unsigned long)btrfs_header_chunk_tree_uuid(c),
1521                             BTRFS_UUID_SIZE);
1522
1523         btrfs_set_node_key(c, &lower_key, 0);
1524         btrfs_set_node_blockptr(c, 0, lower->start);
1525         lower_gen = btrfs_header_generation(lower);
1526         WARN_ON(lower_gen != trans->transid);
1527
1528         btrfs_set_node_ptr_generation(c, 0, lower_gen);
1529
1530         btrfs_mark_buffer_dirty(c);
1531
1532         old = root->node;
1533         root->node = c;
1534
1535         /* the super has an extra ref to root->node */
1536         free_extent_buffer(old);
1537
1538         add_root_to_dirty_list(root);
1539         extent_buffer_get(c);
1540         path->nodes[level] = c;
1541         path->slots[level] = 0;
1542         return 0;
1543 }
1544
1545 /*
1546  * worker function to insert a single pointer in a node.
1547  * the node should have enough room for the pointer already
1548  *
1549  * slot and level indicate where you want the key to go, and
1550  * blocknr is the block the key points to.
1551  *
1552  * returns zero on success and < 0 on any error
1553  */
1554 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1555                       *root, struct btrfs_path *path, struct btrfs_disk_key
1556                       *key, u64 bytenr, int slot, int level)
1557 {
1558         struct extent_buffer *lower;
1559         int nritems;
1560
1561         BUG_ON(!path->nodes[level]);
1562         lower = path->nodes[level];
1563         nritems = btrfs_header_nritems(lower);
1564         if (slot > nritems)
1565                 BUG();
1566         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1567                 BUG();
1568         if (slot != nritems) {
1569                 memmove_extent_buffer(lower,
1570                               btrfs_node_key_ptr_offset(slot + 1),
1571                               btrfs_node_key_ptr_offset(slot),
1572                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1573         }
1574         btrfs_set_node_key(lower, key, slot);
1575         btrfs_set_node_blockptr(lower, slot, bytenr);
1576         WARN_ON(trans->transid == 0);
1577         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
1578         btrfs_set_header_nritems(lower, nritems + 1);
1579         btrfs_mark_buffer_dirty(lower);
1580         return 0;
1581 }
1582
1583 /*
1584  * split the node at the specified level in path in two.
1585  * The path is corrected to point to the appropriate node after the split
1586  *
1587  * Before splitting this tries to make some room in the node by pushing
1588  * left and right, if either one works, it returns right away.
1589  *
1590  * returns 0 on success and < 0 on failure
1591  */
1592 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1593                       *root, struct btrfs_path *path, int level)
1594 {
1595         struct extent_buffer *c;
1596         struct extent_buffer *split;
1597         struct btrfs_disk_key disk_key;
1598         int mid;
1599         int ret;
1600         int wret;
1601         u32 c_nritems;
1602
1603         c = path->nodes[level];
1604         WARN_ON(btrfs_header_generation(c) != trans->transid);
1605         if (c == root->node) {
1606                 /* trying to split the root, lets make a new one */
1607                 ret = insert_new_root(trans, root, path, level + 1);
1608                 if (ret)
1609                         return ret;
1610         } else {
1611                 ret = push_nodes_for_insert(trans, root, path, level);
1612                 c = path->nodes[level];
1613                 if (!ret && btrfs_header_nritems(c) <
1614                     BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
1615                         return 0;
1616                 if (ret < 0)
1617                         return ret;
1618         }
1619
1620         c_nritems = btrfs_header_nritems(c);
1621         mid = (c_nritems + 1) / 2;
1622         btrfs_node_key(c, &disk_key, mid);
1623
1624         split = btrfs_alloc_free_block(trans, root, root->nodesize,
1625                                         root->root_key.objectid,
1626                                         &disk_key, level, c->start, 0);
1627         if (IS_ERR(split))
1628                 return PTR_ERR(split);
1629
1630         memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
1631         btrfs_set_header_level(split, btrfs_header_level(c));
1632         btrfs_set_header_bytenr(split, split->start);
1633         btrfs_set_header_generation(split, trans->transid);
1634         btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
1635         btrfs_set_header_owner(split, root->root_key.objectid);
1636         write_extent_buffer(split, root->fs_info->fsid,
1637                             (unsigned long)btrfs_header_fsid(split),
1638                             BTRFS_FSID_SIZE);
1639         write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
1640                             (unsigned long)btrfs_header_chunk_tree_uuid(split),
1641                             BTRFS_UUID_SIZE);
1642
1643
1644         copy_extent_buffer(split, c,
1645                            btrfs_node_key_ptr_offset(0),
1646                            btrfs_node_key_ptr_offset(mid),
1647                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1648         btrfs_set_header_nritems(split, c_nritems - mid);
1649         btrfs_set_header_nritems(c, mid);
1650         ret = 0;
1651
1652         btrfs_mark_buffer_dirty(c);
1653         btrfs_mark_buffer_dirty(split);
1654
1655         wret = insert_ptr(trans, root, path, &disk_key, split->start,
1656                           path->slots[level + 1] + 1,
1657                           level + 1);
1658         if (wret)
1659                 ret = wret;
1660
1661         if (path->slots[level] >= mid) {
1662                 path->slots[level] -= mid;
1663                 free_extent_buffer(c);
1664                 path->nodes[level] = split;
1665                 path->slots[level + 1] += 1;
1666         } else {
1667                 free_extent_buffer(split);
1668         }
1669         return ret;
1670 }
1671
1672 /*
1673  * how many bytes are required to store the items in a leaf.  start
1674  * and nr indicate which items in the leaf to check.  This totals up the
1675  * space used both by the item structs and the item data
1676  */
1677 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1678 {
1679         int data_len;
1680         int nritems = btrfs_header_nritems(l);
1681         int end = min(nritems, start + nr) - 1;
1682
1683         if (!nr)
1684                 return 0;
1685         data_len = btrfs_item_end_nr(l, start);
1686         data_len = data_len - btrfs_item_offset_nr(l, end);
1687         data_len += sizeof(struct btrfs_item) * nr;
1688         WARN_ON(data_len < 0);
1689         return data_len;
1690 }
1691
1692 /*
1693  * The space between the end of the leaf items and
1694  * the start of the leaf data.  IOW, how much room
1695  * the leaf has left for both items and data
1696  */
1697 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1698 {
1699         int nritems = btrfs_header_nritems(leaf);
1700         int ret;
1701         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1702         if (ret < 0) {
1703                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1704                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
1705                        leaf_space_used(leaf, 0, nritems), nritems);
1706         }
1707         return ret;
1708 }
1709
1710 /*
1711  * push some data in the path leaf to the right, trying to free up at
1712  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1713  *
1714  * returns 1 if the push failed because the other node didn't have enough
1715  * room, 0 if everything worked out and < 0 if there were major errors.
1716  */
1717 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1718                            *root, struct btrfs_path *path, int data_size,
1719                            int empty)
1720 {
1721         struct extent_buffer *left = path->nodes[0];
1722         struct extent_buffer *right;
1723         struct extent_buffer *upper;
1724         struct btrfs_disk_key disk_key;
1725         int slot;
1726         u32 i;
1727         int free_space;
1728         int push_space = 0;
1729         int push_items = 0;
1730         struct btrfs_item *item;
1731         u32 left_nritems;
1732         u32 nr;
1733         u32 right_nritems;
1734         u32 data_end;
1735         u32 this_item_size;
1736         int ret;
1737
1738         slot = path->slots[1];
1739         if (!path->nodes[1]) {
1740                 return 1;
1741         }
1742         upper = path->nodes[1];
1743         if (slot >= btrfs_header_nritems(upper) - 1)
1744                 return 1;
1745
1746         right = read_node_slot(root, upper, slot + 1);
1747         free_space = btrfs_leaf_free_space(root, right);
1748         if (free_space < data_size + sizeof(struct btrfs_item)) {
1749                 free_extent_buffer(right);
1750                 return 1;
1751         }
1752
1753         /* cow and double check */
1754         ret = btrfs_cow_block(trans, root, right, upper,
1755                               slot + 1, &right);
1756         if (ret) {
1757                 free_extent_buffer(right);
1758                 return 1;
1759         }
1760         free_space = btrfs_leaf_free_space(root, right);
1761         if (free_space < data_size + sizeof(struct btrfs_item)) {
1762                 free_extent_buffer(right);
1763                 return 1;
1764         }
1765
1766         left_nritems = btrfs_header_nritems(left);
1767         if (left_nritems == 0) {
1768                 free_extent_buffer(right);
1769                 return 1;
1770         }
1771
1772         if (empty)
1773                 nr = 0;
1774         else
1775                 nr = 1;
1776
1777         i = left_nritems - 1;
1778         while (i >= nr) {
1779                 item = btrfs_item_nr(left, i);
1780
1781                 if (path->slots[0] == i)
1782                         push_space += data_size + sizeof(*item);
1783
1784                 this_item_size = btrfs_item_size(left, item);
1785                 if (this_item_size + sizeof(*item) + push_space > free_space)
1786                         break;
1787                 push_items++;
1788                 push_space += this_item_size + sizeof(*item);
1789                 if (i == 0)
1790                         break;
1791                 i--;
1792         }
1793
1794         if (push_items == 0) {
1795                 free_extent_buffer(right);
1796                 return 1;
1797         }
1798
1799         if (!empty && push_items == left_nritems)
1800                 WARN_ON(1);
1801
1802         /* push left to right */
1803         right_nritems = btrfs_header_nritems(right);
1804
1805         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1806         push_space -= leaf_data_end(root, left);
1807
1808         /* make room in the right data area */
1809         data_end = leaf_data_end(root, right);
1810         memmove_extent_buffer(right,
1811                               btrfs_leaf_data(right) + data_end - push_space,
1812                               btrfs_leaf_data(right) + data_end,
1813                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1814
1815         /* copy from the left data area */
1816         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1817                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1818                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1819                      push_space);
1820
1821         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1822                               btrfs_item_nr_offset(0),
1823                               right_nritems * sizeof(struct btrfs_item));
1824
1825         /* copy the items from left to right */
1826         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1827                    btrfs_item_nr_offset(left_nritems - push_items),
1828                    push_items * sizeof(struct btrfs_item));
1829
1830         /* update the item pointers */
1831         right_nritems += push_items;
1832         btrfs_set_header_nritems(right, right_nritems);
1833         push_space = BTRFS_LEAF_DATA_SIZE(root);
1834         for (i = 0; i < right_nritems; i++) {
1835                 item = btrfs_item_nr(right, i);
1836                 push_space -= btrfs_item_size(right, item);
1837                 btrfs_set_item_offset(right, item, push_space);
1838         }
1839
1840         left_nritems -= push_items;
1841         btrfs_set_header_nritems(left, left_nritems);
1842
1843         if (left_nritems)
1844                 btrfs_mark_buffer_dirty(left);
1845         btrfs_mark_buffer_dirty(right);
1846
1847         btrfs_item_key(right, &disk_key, 0);
1848         btrfs_set_node_key(upper, &disk_key, slot + 1);
1849         btrfs_mark_buffer_dirty(upper);
1850
1851         /* then fixup the leaf pointer in the path */
1852         if (path->slots[0] >= left_nritems) {
1853                 path->slots[0] -= left_nritems;
1854                 free_extent_buffer(path->nodes[0]);
1855                 path->nodes[0] = right;
1856                 path->slots[1] += 1;
1857         } else {
1858                 free_extent_buffer(right);
1859         }
1860         return 0;
1861 }
1862 /*
1863  * push some data in the path leaf to the left, trying to free up at
1864  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1865  */
1866 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1867                           *root, struct btrfs_path *path, int data_size,
1868                           int empty)
1869 {
1870         struct btrfs_disk_key disk_key;
1871         struct extent_buffer *right = path->nodes[0];
1872         struct extent_buffer *left;
1873         int slot;
1874         int i;
1875         int free_space;
1876         int push_space = 0;
1877         int push_items = 0;
1878         struct btrfs_item *item;
1879         u32 old_left_nritems;
1880         u32 right_nritems;
1881         u32 nr;
1882         int ret = 0;
1883         int wret;
1884         u32 this_item_size;
1885         u32 old_left_item_size;
1886
1887         slot = path->slots[1];
1888         if (slot == 0)
1889                 return 1;
1890         if (!path->nodes[1])
1891                 return 1;
1892
1893         right_nritems = btrfs_header_nritems(right);
1894         if (right_nritems == 0) {
1895                 return 1;
1896         }
1897
1898         left = read_node_slot(root, path->nodes[1], slot - 1);
1899         free_space = btrfs_leaf_free_space(root, left);
1900         if (free_space < data_size + sizeof(struct btrfs_item)) {
1901                 free_extent_buffer(left);
1902                 return 1;
1903         }
1904
1905         /* cow and double check */
1906         ret = btrfs_cow_block(trans, root, left,
1907                               path->nodes[1], slot - 1, &left);
1908         if (ret) {
1909                 /* we hit -ENOSPC, but it isn't fatal here */
1910                 free_extent_buffer(left);
1911                 return 1;
1912         }
1913
1914         free_space = btrfs_leaf_free_space(root, left);
1915         if (free_space < data_size + sizeof(struct btrfs_item)) {
1916                 free_extent_buffer(left);
1917                 return 1;
1918         }
1919
1920         if (empty)
1921                 nr = right_nritems;
1922         else
1923                 nr = right_nritems - 1;
1924
1925         for (i = 0; i < nr; i++) {
1926                 item = btrfs_item_nr(right, i);
1927
1928                 if (path->slots[0] == i)
1929                         push_space += data_size + sizeof(*item);
1930
1931                 this_item_size = btrfs_item_size(right, item);
1932                 if (this_item_size + sizeof(*item) + push_space > free_space)
1933                         break;
1934
1935                 push_items++;
1936                 push_space += this_item_size + sizeof(*item);
1937         }
1938
1939         if (push_items == 0) {
1940                 free_extent_buffer(left);
1941                 return 1;
1942         }
1943         if (!empty && push_items == btrfs_header_nritems(right))
1944                 WARN_ON(1);
1945
1946         /* push data from right to left */
1947         copy_extent_buffer(left, right,
1948                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1949                            btrfs_item_nr_offset(0),
1950                            push_items * sizeof(struct btrfs_item));
1951
1952         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1953                      btrfs_item_offset_nr(right, push_items -1);
1954
1955         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1956                      leaf_data_end(root, left) - push_space,
1957                      btrfs_leaf_data(right) +
1958                      btrfs_item_offset_nr(right, push_items - 1),
1959                      push_space);
1960         old_left_nritems = btrfs_header_nritems(left);
1961         BUG_ON(old_left_nritems < 0);
1962
1963         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
1964         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1965                 u32 ioff;
1966
1967                 item = btrfs_item_nr(left, i);
1968                 ioff = btrfs_item_offset(left, item);
1969                 btrfs_set_item_offset(left, item,
1970                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
1971         }
1972         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1973
1974         /* fixup right node */
1975         if (push_items > right_nritems) {
1976                 printk("push items %d nr %u\n", push_items, right_nritems);
1977                 WARN_ON(1);
1978         }
1979
1980         if (push_items < right_nritems) {
1981                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
1982                                                   leaf_data_end(root, right);
1983                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
1984                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
1985                                       btrfs_leaf_data(right) +
1986                                       leaf_data_end(root, right), push_space);
1987
1988                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1989                               btrfs_item_nr_offset(push_items),
1990                              (btrfs_header_nritems(right) - push_items) *
1991                              sizeof(struct btrfs_item));
1992         }
1993         right_nritems -= push_items;
1994         btrfs_set_header_nritems(right, right_nritems);
1995         push_space = BTRFS_LEAF_DATA_SIZE(root);
1996         for (i = 0; i < right_nritems; i++) {
1997                 item = btrfs_item_nr(right, i);
1998                 push_space = push_space - btrfs_item_size(right, item);
1999                 btrfs_set_item_offset(right, item, push_space);
2000         }
2001
2002         btrfs_mark_buffer_dirty(left);
2003         if (right_nritems)
2004                 btrfs_mark_buffer_dirty(right);
2005
2006         btrfs_item_key(right, &disk_key, 0);
2007         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
2008         if (wret)
2009                 ret = wret;
2010
2011         /* then fixup the leaf pointer in the path */
2012         if (path->slots[0] < push_items) {
2013                 path->slots[0] += old_left_nritems;
2014                 free_extent_buffer(path->nodes[0]);
2015                 path->nodes[0] = left;
2016                 path->slots[1] -= 1;
2017         } else {
2018                 free_extent_buffer(left);
2019                 path->slots[0] -= push_items;
2020         }
2021         BUG_ON(path->slots[0] < 0);
2022         return ret;
2023 }
2024
2025 /*
2026  * split the path's leaf in two, making sure there is at least data_size
2027  * available for the resulting leaf level of the path.
2028  *
2029  * returns 0 if all went well and < 0 on failure.
2030  */
2031 static noinline int copy_for_split(struct btrfs_trans_handle *trans,
2032                                struct btrfs_root *root,
2033                                struct btrfs_path *path,
2034                                struct extent_buffer *l,
2035                                struct extent_buffer *right,
2036                                int slot, int mid, int nritems)
2037 {
2038         int data_copy_size;
2039         int rt_data_off;
2040         int i;
2041         int ret = 0;
2042         int wret;
2043         struct btrfs_disk_key disk_key;
2044
2045         nritems = nritems - mid;
2046         btrfs_set_header_nritems(right, nritems);
2047         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
2048
2049         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2050                            btrfs_item_nr_offset(mid),
2051                            nritems * sizeof(struct btrfs_item));
2052
2053         copy_extent_buffer(right, l,
2054                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2055                      data_copy_size, btrfs_leaf_data(l) +
2056                      leaf_data_end(root, l), data_copy_size);
2057
2058         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2059                       btrfs_item_end_nr(l, mid);
2060
2061         for (i = 0; i < nritems; i++) {
2062                 struct btrfs_item *item = btrfs_item_nr(right, i);
2063                 u32 ioff = btrfs_item_offset(right, item);
2064                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2065         }
2066
2067         btrfs_set_header_nritems(l, mid);
2068         ret = 0;
2069         btrfs_item_key(right, &disk_key, 0);
2070         wret = insert_ptr(trans, root, path, &disk_key, right->start,
2071                           path->slots[1] + 1, 1);
2072         if (wret)
2073                 ret = wret;
2074
2075         btrfs_mark_buffer_dirty(right);
2076         btrfs_mark_buffer_dirty(l);
2077         BUG_ON(path->slots[0] != slot);
2078
2079         if (mid <= slot) {
2080                 free_extent_buffer(path->nodes[0]);
2081                 path->nodes[0] = right;
2082                 path->slots[0] -= mid;
2083                 path->slots[1] += 1;
2084         } else {
2085                 free_extent_buffer(right);
2086         }
2087
2088         BUG_ON(path->slots[0] < 0);
2089
2090         return ret;
2091 }
2092
2093 /*
2094  * split the path's leaf in two, making sure there is at least data_size
2095  * available for the resulting leaf level of the path.
2096  *
2097  * returns 0 if all went well and < 0 on failure.
2098  */
2099 static noinline int split_leaf(struct btrfs_trans_handle *trans,
2100                                struct btrfs_root *root,
2101                                struct btrfs_key *ins_key,
2102                                struct btrfs_path *path, int data_size,
2103                                int extend)
2104 {
2105         struct btrfs_disk_key disk_key;
2106         struct extent_buffer *l;
2107         u32 nritems;
2108         int mid;
2109         int slot;
2110         struct extent_buffer *right;
2111         int ret = 0;
2112         int wret;
2113         int split;
2114         int num_doubles = 0;
2115
2116         /* first try to make some room by pushing left and right */
2117         if (data_size && ins_key->type != BTRFS_DIR_ITEM_KEY) {
2118                 wret = push_leaf_right(trans, root, path, data_size, 0);
2119                 if (wret < 0)
2120                         return wret;
2121                 if (wret) {
2122                         wret = push_leaf_left(trans, root, path, data_size, 0);
2123                         if (wret < 0)
2124                                 return wret;
2125                 }
2126                 l = path->nodes[0];
2127
2128                 /* did the pushes work? */
2129                 if (btrfs_leaf_free_space(root, l) >= data_size)
2130                         return 0;
2131         }
2132
2133         if (!path->nodes[1]) {
2134                 ret = insert_new_root(trans, root, path, 1);
2135                 if (ret)
2136                         return ret;
2137         }
2138 again:
2139         split = 1;
2140         l = path->nodes[0];
2141         slot = path->slots[0];
2142         nritems = btrfs_header_nritems(l);
2143         mid = (nritems + 1) / 2;
2144
2145         if (mid <= slot) {
2146                 if (nritems == 1 ||
2147                     leaf_space_used(l, mid, nritems - mid) + data_size >
2148                         BTRFS_LEAF_DATA_SIZE(root)) {
2149                         if (slot >= nritems) {
2150                                 split = 0;
2151                         } else {
2152                                 mid = slot;
2153                                 if (mid != nritems &&
2154                                     leaf_space_used(l, mid, nritems - mid) +
2155                                     data_size > BTRFS_LEAF_DATA_SIZE(root)) {
2156                                         split = 2;
2157                                 }
2158                         }
2159                 }
2160         } else {
2161                 if (leaf_space_used(l, 0, mid) + data_size >
2162                         BTRFS_LEAF_DATA_SIZE(root)) {
2163                         if (!extend && data_size && slot == 0) {
2164                                 split = 0;
2165                         } else if ((extend || !data_size) && slot == 0) {
2166                                 mid = 1;
2167                         } else {
2168                                 mid = slot;
2169                                 if (mid != nritems &&
2170                                     leaf_space_used(l, mid, nritems - mid) +
2171                                     data_size > BTRFS_LEAF_DATA_SIZE(root)) {
2172                                         split = 2 ;
2173                                 }
2174                         }
2175                 }
2176         }
2177
2178         if (split == 0)
2179                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
2180         else
2181                 btrfs_item_key(l, &disk_key, mid);
2182
2183         right = btrfs_alloc_free_block(trans, root, root->leafsize,
2184                                         root->root_key.objectid,
2185                                         &disk_key, 0, l->start, 0);
2186         if (IS_ERR(right)) {
2187                 BUG_ON(1);
2188                 return PTR_ERR(right);
2189         }
2190
2191         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
2192         btrfs_set_header_bytenr(right, right->start);
2193         btrfs_set_header_generation(right, trans->transid);
2194         btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
2195         btrfs_set_header_owner(right, root->root_key.objectid);
2196         btrfs_set_header_level(right, 0);
2197         write_extent_buffer(right, root->fs_info->fsid,
2198                             (unsigned long)btrfs_header_fsid(right),
2199                             BTRFS_FSID_SIZE);
2200
2201         write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
2202                             (unsigned long)btrfs_header_chunk_tree_uuid(right),
2203                             BTRFS_UUID_SIZE);
2204
2205         if (split == 0) {
2206                 if (mid <= slot) {
2207                         btrfs_set_header_nritems(right, 0);
2208                         wret = insert_ptr(trans, root, path,
2209                                           &disk_key, right->start,
2210                                           path->slots[1] + 1, 1);
2211                         if (wret)
2212                                 ret = wret;
2213
2214                         free_extent_buffer(path->nodes[0]);
2215                         path->nodes[0] = right;
2216                         path->slots[0] = 0;
2217                         path->slots[1] += 1;
2218                 } else {
2219                         btrfs_set_header_nritems(right, 0);
2220                         wret = insert_ptr(trans, root, path,
2221                                           &disk_key,
2222                                           right->start,
2223                                           path->slots[1], 1);
2224                         if (wret)
2225                                 ret = wret;
2226                         free_extent_buffer(path->nodes[0]);
2227                         path->nodes[0] = right;
2228                         path->slots[0] = 0;
2229                         if (path->slots[1] == 0) {
2230                                 wret = fixup_low_keys(trans, root,
2231                                                 path, &disk_key, 1);
2232                                 if (wret)
2233                                         ret = wret;
2234                         }
2235                 }
2236                 btrfs_mark_buffer_dirty(right);
2237                 return ret;
2238         }
2239
2240         ret = copy_for_split(trans, root, path, l, right, slot, mid, nritems);
2241         BUG_ON(ret);
2242
2243         if (split == 2) {
2244                 BUG_ON(num_doubles != 0);
2245                 num_doubles++;
2246                 goto again;
2247         }
2248
2249         return ret;
2250 }
2251
2252 /*
2253  * This function splits a single item into two items,
2254  * giving 'new_key' to the new item and splitting the
2255  * old one at split_offset (from the start of the item).
2256  *
2257  * The path may be released by this operation.  After
2258  * the split, the path is pointing to the old item.  The
2259  * new item is going to be in the same node as the old one.
2260  *
2261  * Note, the item being split must be smaller enough to live alone on
2262  * a tree block with room for one extra struct btrfs_item
2263  *
2264  * This allows us to split the item in place, keeping a lock on the
2265  * leaf the entire time.
2266  */
2267 int btrfs_split_item(struct btrfs_trans_handle *trans,
2268                      struct btrfs_root *root,
2269                      struct btrfs_path *path,
2270                      struct btrfs_key *new_key,
2271                      unsigned long split_offset)
2272 {
2273         u32 item_size;
2274         struct extent_buffer *leaf;
2275         struct btrfs_key orig_key;
2276         struct btrfs_item *item;
2277         struct btrfs_item *new_item;
2278         int ret = 0;
2279         int slot;
2280         u32 nritems;
2281         u32 orig_offset;
2282         struct btrfs_disk_key disk_key;
2283         char *buf;
2284
2285         leaf = path->nodes[0];
2286         btrfs_item_key_to_cpu(leaf, &orig_key, path->slots[0]);
2287         if (btrfs_leaf_free_space(root, leaf) >= sizeof(struct btrfs_item))
2288                 goto split;
2289
2290         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
2291         btrfs_release_path(root, path);
2292
2293         path->search_for_split = 1;
2294
2295         ret = btrfs_search_slot(trans, root, &orig_key, path, 0, 1);
2296         path->search_for_split = 0;
2297
2298         /* if our item isn't there or got smaller, return now */
2299         if (ret != 0 || item_size != btrfs_item_size_nr(path->nodes[0],
2300                                                         path->slots[0])) {
2301                 return -EAGAIN;
2302         }
2303
2304         ret = split_leaf(trans, root, &orig_key, path, 0, 0);
2305         BUG_ON(ret);
2306
2307         BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
2308         leaf = path->nodes[0];
2309
2310 split:
2311         item = btrfs_item_nr(leaf, path->slots[0]);
2312         orig_offset = btrfs_item_offset(leaf, item);
2313         item_size = btrfs_item_size(leaf, item);
2314
2315
2316         buf = kmalloc(item_size, GFP_NOFS);
2317         read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
2318                             path->slots[0]), item_size);
2319         slot = path->slots[0] + 1;
2320         leaf = path->nodes[0];
2321
2322         nritems = btrfs_header_nritems(leaf);
2323
2324         if (slot != nritems) {
2325                 /* shift the items */
2326                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
2327                               btrfs_item_nr_offset(slot),
2328                               (nritems - slot) * sizeof(struct btrfs_item));
2329
2330         }
2331
2332         btrfs_cpu_key_to_disk(&disk_key, new_key);
2333         btrfs_set_item_key(leaf, &disk_key, slot);
2334
2335         new_item = btrfs_item_nr(leaf, slot);
2336
2337         btrfs_set_item_offset(leaf, new_item, orig_offset);
2338         btrfs_set_item_size(leaf, new_item, item_size - split_offset);
2339
2340         btrfs_set_item_offset(leaf, item,
2341                               orig_offset + item_size - split_offset);
2342         btrfs_set_item_size(leaf, item, split_offset);
2343
2344         btrfs_set_header_nritems(leaf, nritems + 1);
2345
2346         /* write the data for the start of the original item */
2347         write_extent_buffer(leaf, buf,
2348                             btrfs_item_ptr_offset(leaf, path->slots[0]),
2349                             split_offset);
2350
2351         /* write the data for the new item */
2352         write_extent_buffer(leaf, buf + split_offset,
2353                             btrfs_item_ptr_offset(leaf, slot),
2354                             item_size - split_offset);
2355         btrfs_mark_buffer_dirty(leaf);
2356
2357         ret = 0;
2358         if (btrfs_leaf_free_space(root, leaf) < 0) {
2359                 btrfs_print_leaf(root, leaf);
2360                 BUG();
2361         }
2362         kfree(buf);
2363         return ret;
2364 }
2365
2366 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
2367                         struct btrfs_root *root,
2368                         struct btrfs_path *path,
2369                         u32 new_size, int from_end)
2370 {
2371         int ret = 0;
2372         int slot;
2373         int slot_orig;
2374         struct extent_buffer *leaf;
2375         struct btrfs_item *item;
2376         u32 nritems;
2377         unsigned int data_end;
2378         unsigned int old_data_start;
2379         unsigned int old_size;
2380         unsigned int size_diff;
2381         int i;
2382
2383         slot_orig = path->slots[0];
2384         leaf = path->nodes[0];
2385         slot = path->slots[0];
2386
2387         old_size = btrfs_item_size_nr(leaf, slot);
2388         if (old_size == new_size)
2389                 return 0;
2390
2391         nritems = btrfs_header_nritems(leaf);
2392         data_end = leaf_data_end(root, leaf);
2393
2394         old_data_start = btrfs_item_offset_nr(leaf, slot);
2395
2396         size_diff = old_size - new_size;
2397
2398         BUG_ON(slot < 0);
2399         BUG_ON(slot >= nritems);
2400
2401         /*
2402          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2403          */
2404         /* first correct the data pointers */
2405         for (i = slot; i < nritems; i++) {
2406                 u32 ioff;
2407                 item = btrfs_item_nr(leaf, i);
2408                 ioff = btrfs_item_offset(leaf, item);
2409                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2410         }
2411
2412         /* shift the data */
2413         if (from_end) {
2414                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2415                               data_end + size_diff, btrfs_leaf_data(leaf) +
2416                               data_end, old_data_start + new_size - data_end);
2417         } else {
2418                 struct btrfs_disk_key disk_key;
2419                 u64 offset;
2420
2421                 btrfs_item_key(leaf, &disk_key, slot);
2422
2423                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
2424                         unsigned long ptr;
2425                         struct btrfs_file_extent_item *fi;
2426
2427                         fi = btrfs_item_ptr(leaf, slot,
2428                                             struct btrfs_file_extent_item);
2429                         fi = (struct btrfs_file_extent_item *)(
2430                              (unsigned long)fi - size_diff);
2431
2432                         if (btrfs_file_extent_type(leaf, fi) ==
2433                             BTRFS_FILE_EXTENT_INLINE) {
2434                                 ptr = btrfs_item_ptr_offset(leaf, slot);
2435                                 memmove_extent_buffer(leaf, ptr,
2436                                         (unsigned long)fi,
2437                                         offsetof(struct btrfs_file_extent_item,
2438                                                  disk_bytenr));
2439                         }
2440                 }
2441
2442                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2443                               data_end + size_diff, btrfs_leaf_data(leaf) +
2444                               data_end, old_data_start - data_end);
2445
2446                 offset = btrfs_disk_key_offset(&disk_key);
2447                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
2448                 btrfs_set_item_key(leaf, &disk_key, slot);
2449                 if (slot == 0)
2450                         fixup_low_keys(trans, root, path, &disk_key, 1);
2451         }
2452
2453         item = btrfs_item_nr(leaf, slot);
2454         btrfs_set_item_size(leaf, item, new_size);
2455         btrfs_mark_buffer_dirty(leaf);
2456
2457         ret = 0;
2458         if (btrfs_leaf_free_space(root, leaf) < 0) {
2459                 btrfs_print_leaf(root, leaf);
2460                 BUG();
2461         }
2462         return ret;
2463 }
2464
2465 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2466                       struct btrfs_root *root, struct btrfs_path *path,
2467                       u32 data_size)
2468 {
2469         int ret = 0;
2470         int slot;
2471         int slot_orig;
2472         struct extent_buffer *leaf;
2473         struct btrfs_item *item;
2474         u32 nritems;
2475         unsigned int data_end;
2476         unsigned int old_data;
2477         unsigned int old_size;
2478         int i;
2479
2480         slot_orig = path->slots[0];
2481         leaf = path->nodes[0];
2482
2483         nritems = btrfs_header_nritems(leaf);
2484         data_end = leaf_data_end(root, leaf);
2485
2486         if (btrfs_leaf_free_space(root, leaf) < data_size) {
2487                 btrfs_print_leaf(root, leaf);
2488                 BUG();
2489         }
2490         slot = path->slots[0];
2491         old_data = btrfs_item_end_nr(leaf, slot);
2492
2493         BUG_ON(slot < 0);
2494         if (slot >= nritems) {
2495                 btrfs_print_leaf(root, leaf);
2496                 printk("slot %d too large, nritems %d\n", slot, nritems);
2497                 BUG_ON(1);
2498         }
2499
2500         /*
2501          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2502          */
2503         /* first correct the data pointers */
2504         for (i = slot; i < nritems; i++) {
2505                 u32 ioff;
2506                 item = btrfs_item_nr(leaf, i);
2507                 ioff = btrfs_item_offset(leaf, item);
2508                 btrfs_set_item_offset(leaf, item, ioff - data_size);
2509         }
2510
2511         /* shift the data */
2512         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2513                       data_end - data_size, btrfs_leaf_data(leaf) +
2514                       data_end, old_data - data_end);
2515
2516         data_end = old_data;
2517         old_size = btrfs_item_size_nr(leaf, slot);
2518         item = btrfs_item_nr(leaf, slot);
2519         btrfs_set_item_size(leaf, item, old_size + data_size);
2520         btrfs_mark_buffer_dirty(leaf);
2521
2522         ret = 0;
2523         if (btrfs_leaf_free_space(root, leaf) < 0) {
2524                 btrfs_print_leaf(root, leaf);
2525                 BUG();
2526         }
2527         return ret;
2528 }
2529
2530 /*
2531  * Given a key and some data, insert an item into the tree.
2532  * This does all the path init required, making room in the tree if needed.
2533  */
2534 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
2535                             struct btrfs_root *root,
2536                             struct btrfs_path *path,
2537                             struct btrfs_key *cpu_key, u32 *data_size,
2538                             int nr)
2539 {
2540         struct extent_buffer *leaf;
2541         struct btrfs_item *item;
2542         int ret = 0;
2543         int slot;
2544         int slot_orig;
2545         int i;
2546         u32 nritems;
2547         u32 total_size = 0;
2548         u32 total_data = 0;
2549         unsigned int data_end;
2550         struct btrfs_disk_key disk_key;
2551
2552         for (i = 0; i < nr; i++) {
2553                 total_data += data_size[i];
2554         }
2555
2556         /* create a root if there isn't one */
2557         if (!root->node)
2558                 BUG();
2559
2560         total_size = total_data + (nr - 1) * sizeof(struct btrfs_item);
2561         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
2562         if (ret == 0) {
2563                 return -EEXIST;
2564         }
2565         if (ret < 0)
2566                 goto out;
2567
2568         slot_orig = path->slots[0];
2569         leaf = path->nodes[0];
2570
2571         nritems = btrfs_header_nritems(leaf);
2572         data_end = leaf_data_end(root, leaf);
2573
2574         if (btrfs_leaf_free_space(root, leaf) <
2575             sizeof(struct btrfs_item) + total_size) {
2576                 btrfs_print_leaf(root, leaf);
2577                 printk("not enough freespace need %u have %d\n",
2578                        total_size, btrfs_leaf_free_space(root, leaf));
2579                 BUG();
2580         }
2581
2582         slot = path->slots[0];
2583         BUG_ON(slot < 0);
2584
2585         if (slot != nritems) {
2586                 int i;
2587                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2588
2589                 if (old_data < data_end) {
2590                         btrfs_print_leaf(root, leaf);
2591                         printk("slot %d old_data %d data_end %d\n",
2592                                slot, old_data, data_end);
2593                         BUG_ON(1);
2594                 }
2595                 /*
2596                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2597                  */
2598                 /* first correct the data pointers */
2599                 for (i = slot; i < nritems; i++) {
2600                         u32 ioff;
2601
2602                         item = btrfs_item_nr(leaf, i);
2603                         ioff = btrfs_item_offset(leaf, item);
2604                         btrfs_set_item_offset(leaf, item, ioff - total_data);
2605                 }
2606
2607                 /* shift the items */
2608                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
2609                               btrfs_item_nr_offset(slot),
2610                               (nritems - slot) * sizeof(struct btrfs_item));
2611
2612                 /* shift the data */
2613                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2614                               data_end - total_data, btrfs_leaf_data(leaf) +
2615                               data_end, old_data - data_end);
2616                 data_end = old_data;
2617         }
2618
2619         /* setup the item for the new data */
2620         for (i = 0; i < nr; i++) {
2621                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
2622                 btrfs_set_item_key(leaf, &disk_key, slot + i);
2623                 item = btrfs_item_nr(leaf, slot + i);
2624                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
2625                 data_end -= data_size[i];
2626                 btrfs_set_item_size(leaf, item, data_size[i]);
2627         }
2628         btrfs_set_header_nritems(leaf, nritems + nr);
2629         btrfs_mark_buffer_dirty(leaf);
2630
2631         ret = 0;
2632         if (slot == 0) {
2633                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2634                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2635         }
2636
2637         if (btrfs_leaf_free_space(root, leaf) < 0) {
2638                 btrfs_print_leaf(root, leaf);
2639                 BUG();
2640         }
2641
2642 out:
2643         return ret;
2644 }
2645
2646 /*
2647  * Given a key and some data, insert an item into the tree.
2648  * This does all the path init required, making room in the tree if needed.
2649  */
2650 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2651                       *root, struct btrfs_key *cpu_key, void *data, u32
2652                       data_size)
2653 {
2654         int ret = 0;
2655         struct btrfs_path *path;
2656         struct extent_buffer *leaf;
2657         unsigned long ptr;
2658
2659         path = btrfs_alloc_path();
2660         BUG_ON(!path);
2661         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2662         if (!ret) {
2663                 leaf = path->nodes[0];
2664                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2665                 write_extent_buffer(leaf, data, ptr, data_size);
2666                 btrfs_mark_buffer_dirty(leaf);
2667         }
2668         btrfs_free_path(path);
2669         return ret;
2670 }
2671
2672 /*
2673  * delete the pointer from a given node.
2674  *
2675  * If the delete empties a node, the node is removed from the tree,
2676  * continuing all the way the root if required.  The root is converted into
2677  * a leaf if all the nodes are emptied.
2678  */
2679 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2680                    struct btrfs_path *path, int level, int slot)
2681 {
2682         struct extent_buffer *parent = path->nodes[level];
2683         u32 nritems;
2684         int ret = 0;
2685         int wret;
2686
2687         nritems = btrfs_header_nritems(parent);
2688         if (slot != nritems -1) {
2689                 memmove_extent_buffer(parent,
2690                               btrfs_node_key_ptr_offset(slot),
2691                               btrfs_node_key_ptr_offset(slot + 1),
2692                               sizeof(struct btrfs_key_ptr) *
2693                               (nritems - slot - 1));
2694         }
2695         nritems--;
2696         btrfs_set_header_nritems(parent, nritems);
2697         if (nritems == 0 && parent == root->node) {
2698                 BUG_ON(btrfs_header_level(root->node) != 1);
2699                 /* just turn the root into a leaf and break */
2700                 btrfs_set_header_level(root->node, 0);
2701         } else if (slot == 0) {
2702                 struct btrfs_disk_key disk_key;
2703
2704                 btrfs_node_key(parent, &disk_key, 0);
2705                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2706                 if (wret)
2707                         ret = wret;
2708         }
2709         btrfs_mark_buffer_dirty(parent);
2710         return ret;
2711 }
2712
2713 /*
2714  * a helper function to delete the leaf pointed to by path->slots[1] and
2715  * path->nodes[1].
2716  *
2717  * This deletes the pointer in path->nodes[1] and frees the leaf
2718  * block extent.  zero is returned if it all worked out, < 0 otherwise.
2719  *
2720  * The path must have already been setup for deleting the leaf, including
2721  * all the proper balancing.  path->nodes[1] must be locked.
2722  */
2723 static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
2724                                    struct btrfs_root *root,
2725                                    struct btrfs_path *path,
2726                                    struct extent_buffer *leaf)
2727 {
2728         int ret;
2729
2730         WARN_ON(btrfs_header_generation(leaf) != trans->transid);
2731         ret = del_ptr(trans, root, path, 1, path->slots[1]);
2732         if (ret)
2733                 return ret;
2734
2735         ret = btrfs_free_extent(trans, root, leaf->start, leaf->len,
2736                                 0, root->root_key.objectid, 0, 0);
2737         return ret;
2738 }
2739
2740 /*
2741  * delete the item at the leaf level in path.  If that empties
2742  * the leaf, remove it from the tree
2743  */
2744 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2745                     struct btrfs_path *path, int slot, int nr)
2746 {
2747         struct extent_buffer *leaf;
2748         struct btrfs_item *item;
2749         int last_off;
2750         int dsize = 0;
2751         int ret = 0;
2752         int wret;
2753         int i;
2754         u32 nritems;
2755
2756         leaf = path->nodes[0];
2757         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
2758
2759         for (i = 0; i < nr; i++)
2760                 dsize += btrfs_item_size_nr(leaf, slot + i);
2761
2762         nritems = btrfs_header_nritems(leaf);
2763
2764         if (slot + nr != nritems) {
2765                 int i;
2766                 int data_end = leaf_data_end(root, leaf);
2767
2768                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2769                               data_end + dsize,
2770                               btrfs_leaf_data(leaf) + data_end,
2771                               last_off - data_end);
2772
2773                 for (i = slot + nr; i < nritems; i++) {
2774                         u32 ioff;
2775
2776                         item = btrfs_item_nr(leaf, i);
2777                         ioff = btrfs_item_offset(leaf, item);
2778                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2779                 }
2780
2781                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2782                               btrfs_item_nr_offset(slot + nr),
2783                               sizeof(struct btrfs_item) *
2784                               (nritems - slot - nr));
2785         }
2786         btrfs_set_header_nritems(leaf, nritems - nr);
2787         nritems -= nr;
2788
2789         /* delete the leaf if we've emptied it */
2790         if (nritems == 0) {
2791                 if (leaf == root->node) {
2792                         btrfs_set_header_level(leaf, 0);
2793                 } else {
2794                         clean_tree_block(trans, root, leaf);
2795                         wait_on_tree_block_writeback(root, leaf);
2796
2797                         wret = btrfs_del_leaf(trans, root, path, leaf);
2798                         BUG_ON(ret);
2799                         if (wret)
2800                                 ret = wret;
2801                 }
2802         } else {
2803                 int used = leaf_space_used(leaf, 0, nritems);
2804                 if (slot == 0) {
2805                         struct btrfs_disk_key disk_key;
2806
2807                         btrfs_item_key(leaf, &disk_key, 0);
2808                         wret = fixup_low_keys(trans, root, path,
2809                                               &disk_key, 1);
2810                         if (wret)
2811                                 ret = wret;
2812                 }
2813
2814                 /* delete the leaf if it is mostly empty */
2815                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 4) {
2816                         /* push_leaf_left fixes the path.
2817                          * make sure the path still points to our leaf
2818                          * for possible call to del_ptr below
2819                          */
2820                         slot = path->slots[1];
2821                         extent_buffer_get(leaf);
2822
2823                         wret = push_leaf_left(trans, root, path, 1, 1);
2824                         if (wret < 0 && wret != -ENOSPC)
2825                                 ret = wret;
2826
2827                         if (path->nodes[0] == leaf &&
2828                             btrfs_header_nritems(leaf)) {
2829                                 wret = push_leaf_right(trans, root, path, 1, 1);
2830                                 if (wret < 0 && wret != -ENOSPC)
2831                                         ret = wret;
2832                         }
2833
2834                         if (btrfs_header_nritems(leaf) == 0) {
2835                                 clean_tree_block(trans, root, leaf);
2836                                 wait_on_tree_block_writeback(root, leaf);
2837
2838                                 path->slots[1] = slot;
2839                                 ret = btrfs_del_leaf(trans, root, path, leaf);
2840                                 BUG_ON(ret);
2841                                 free_extent_buffer(leaf);
2842
2843                         } else {
2844                                 btrfs_mark_buffer_dirty(leaf);
2845                                 free_extent_buffer(leaf);
2846                         }
2847                 } else {
2848                         btrfs_mark_buffer_dirty(leaf);
2849                 }
2850         }
2851         return ret;
2852 }
2853
2854 /*
2855  * walk up the tree as far as required to find the previous leaf.
2856  * returns 0 if it found something or 1 if there are no lesser leaves.
2857  * returns < 0 on io errors.
2858  */
2859 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2860 {
2861         int slot;
2862         int level = 1;
2863         struct extent_buffer *c;
2864         struct extent_buffer *next = NULL;
2865
2866         while(level < BTRFS_MAX_LEVEL) {
2867                 if (!path->nodes[level])
2868                         return 1;
2869
2870                 slot = path->slots[level];
2871                 c = path->nodes[level];
2872                 if (slot == 0) {
2873                         level++;
2874                         if (level == BTRFS_MAX_LEVEL)
2875                                 return 1;
2876                         continue;
2877                 }
2878                 slot--;
2879
2880                 if (next)
2881                         free_extent_buffer(next);
2882
2883                 next = read_node_slot(root, c, slot);
2884                 break;
2885         }
2886         path->slots[level] = slot;
2887         while(1) {
2888                 level--;
2889                 c = path->nodes[level];
2890                 free_extent_buffer(c);
2891                 slot = btrfs_header_nritems(next);
2892                 if (slot != 0)
2893                         slot--;
2894                 path->nodes[level] = next;
2895                 path->slots[level] = slot;
2896                 if (!level)
2897                         break;
2898                 next = read_node_slot(root, next, slot);
2899         }
2900         return 0;
2901 }
2902
2903 /*
2904  * walk up the tree as far as required to find the next leaf.
2905  * returns 0 if it found something or 1 if there are no greater leaves.
2906  * returns < 0 on io errors.
2907  */
2908 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2909 {
2910         int slot;
2911         int level = 1;
2912         struct extent_buffer *c;
2913         struct extent_buffer *next = NULL;
2914
2915         while(level < BTRFS_MAX_LEVEL) {
2916                 if (!path->nodes[level])
2917                         return 1;
2918
2919                 slot = path->slots[level] + 1;
2920                 c = path->nodes[level];
2921                 if (slot >= btrfs_header_nritems(c)) {
2922                         level++;
2923                         if (level == BTRFS_MAX_LEVEL)
2924                                 return 1;
2925                         continue;
2926                 }
2927
2928                 if (next)
2929                         free_extent_buffer(next);
2930
2931                 if (path->reada)
2932                         reada_for_search(root, path, level, slot, 0);
2933
2934                 next = read_node_slot(root, c, slot);
2935                 break;
2936         }
2937         path->slots[level] = slot;
2938         while(1) {
2939                 level--;
2940                 c = path->nodes[level];
2941                 free_extent_buffer(c);
2942                 path->nodes[level] = next;
2943                 path->slots[level] = 0;
2944                 if (!level)
2945                         break;
2946                 if (path->reada)
2947                         reada_for_search(root, path, level, 0, 0);
2948                 next = read_node_slot(root, next, 0);
2949         }
2950         return 0;
2951 }
2952
2953 int btrfs_previous_item(struct btrfs_root *root,
2954                         struct btrfs_path *path, u64 min_objectid,
2955                         int type)
2956 {
2957         struct btrfs_key found_key;
2958         struct extent_buffer *leaf;
2959         int ret;
2960
2961         while(1) {
2962                 if (path->slots[0] == 0) {
2963                         ret = btrfs_prev_leaf(root, path);
2964                         if (ret != 0)
2965                                 return ret;
2966                 } else {
2967                         path->slots[0]--;
2968                 }
2969                 leaf = path->nodes[0];
2970                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2971                 if (found_key.type == type)
2972                         return 0;
2973         }
2974         return 1;
2975 }
2976