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