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