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 #include "internal.h"
  24
  25 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  26                       *root, struct btrfs_path *path, int level);
  27 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  28                       *root, struct btrfs_key *ins_key,
  29                       struct btrfs_path *path, int data_size, int extend);
  30 static int push_node_left(struct btrfs_trans_handle *trans,
  31                           struct btrfs_root *root, struct extent_buffer *dst,
  32                           struct extent_buffer *src, int empty);
  33 static int balance_node_right(struct btrfs_trans_handle *trans,
  34                               struct btrfs_root *root,
  35                               struct extent_buffer *dst_buf,
  36                               struct extent_buffer *src_buf);
  37
  38 inline void btrfs_init_path(struct btrfs_path *p)
  39 {
  40         memset(p, 0, sizeof(*p));
  41 }
  42
  43 struct btrfs_path *btrfs_alloc_path(void)
  44 {
  45         struct btrfs_path *path;
  46         path = kzalloc(sizeof(struct btrfs_path), GFP_NOFS);
  47         return path;
  48 }
  49
  50 void btrfs_free_path(struct btrfs_path *p)
  51 {
  52         if (!p)
  53                 return;
  54         btrfs_release_path(p);
  55         kfree(p);
  56 }
  57
  58 void btrfs_release_path(struct btrfs_path *p)
  59 {
  60         int i;
  61         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  62                 if (!p->nodes[i])
  63                         continue;
  64                 free_extent_buffer(p->nodes[i]);
  65         }
  66         memset(p, 0, sizeof(*p));
  67 }
  68
  69 void add_root_to_dirty_list(struct btrfs_root *root)
  70 {
  71         if (root->track_dirty && list_empty(&root->dirty_list)) {
  72                 list_add(&root->dirty_list,
  73                          &root->fs_info->dirty_cowonly_roots);
  74         }
  75 }
  76
  77 int btrfs_copy_root(struct btrfs_trans_handle *trans,
  78                       struct btrfs_root *root,
  79                       struct extent_buffer *buf,
  80                       struct extent_buffer **cow_ret, u64 new_root_objectid)
  81 {
  82         struct extent_buffer *cow;
  83         int ret = 0;
  84         int level;
  85         struct btrfs_root *new_root;
  86         struct btrfs_disk_key disk_key;
  87
  88         new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
  89         if (!new_root)
  90                 return -ENOMEM;
  91
  92         memcpy(new_root, root, sizeof(*new_root));
  93         new_root->root_key.objectid = new_root_objectid;
  94
  95         WARN_ON(root->ref_cows && trans->transid !=
  96                 root->fs_info->running_transaction->transid);
  97         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
  98
  99         level = btrfs_header_level(buf);
 100         if (level == 0)
 101                 btrfs_item_key(buf, &disk_key, 0);
 102         else
 103                 btrfs_node_key(buf, &disk_key, 0);
 104         cow = btrfs_alloc_free_block(trans, new_root, buf->len,
 105                                      new_root_objectid, &disk_key,
 106                                      level, buf->start, 0);
 107         if (IS_ERR(cow)) {
 108                 kfree(new_root);
 109                 return PTR_ERR(cow);
 110         }
 111
 112         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 113         btrfs_set_header_bytenr(cow, cow->start);
 114         btrfs_set_header_generation(cow, trans->transid);
 115         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 116         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 117                                      BTRFS_HEADER_FLAG_RELOC);
 118         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 119                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 120         else
 121                 btrfs_set_header_owner(cow, new_root_objectid);
 122
 123         write_extent_buffer(cow, root->fs_info->fsid,
 124                             btrfs_header_fsid(), BTRFS_FSID_SIZE);
 125
 126         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 127         ret = btrfs_inc_ref(trans, new_root, cow, 0);
 128         kfree(new_root);
 129
 130         if (ret)
 131                 return ret;
 132
 133         btrfs_mark_buffer_dirty(cow);
 134         *cow_ret = cow;
 135         return 0;
 136 }
 137
 138 /*
 139  * check if the tree block can be shared by multiple trees
 140  */
 141 static int btrfs_block_can_be_shared(struct btrfs_root *root,
 142                                      struct extent_buffer *buf)
 143 {
 144         /*
 145          * Tree blocks not in reference counted trees and tree roots
 146          * are never shared. If a block was allocated after the last
 147          * snapshot and the block was not allocated by tree relocation,
 148          * we know the block is not shared.
 149          */
 150         if (root->ref_cows &&
 151             buf != root->node && buf != root->commit_root &&
 152             (btrfs_header_generation(buf) <=
 153              btrfs_root_last_snapshot(&root->root_item) ||
 154              btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 155                 return 1;
 156 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 157         if (root->ref_cows &&
 158             btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 159                 return 1;
 160 #endif
 161         return 0;
 162 }
 163
 164 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 165                                        struct btrfs_root *root,
 166                                        struct extent_buffer *buf,
 167                                        struct extent_buffer *cow)
 168 {
 169         u64 refs;
 170         u64 owner;
 171         u64 flags;
 172         u64 new_flags = 0;
 173         int ret;
 174
 175         /*
 176          * Backrefs update rules:
 177          *
 178          * Always use full backrefs for extent pointers in tree block
 179          * allocated by tree relocation.
 180          *
 181          * If a shared tree block is no longer referenced by its owner
 182          * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 183          * use full backrefs for extent pointers in tree block.
 184          *
 185          * If a tree block is been relocating
 186          * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
 187          * use full backrefs for extent pointers in tree block.
 188          * The reason for this is some operations (such as drop tree)
 189          * are only allowed for blocks use full backrefs.
 190          */
 191
 192         if (btrfs_block_can_be_shared(root, buf)) {
 193                 ret = btrfs_lookup_extent_info(trans, root, buf->start,
 194                                                btrfs_header_level(buf), 1,
 195                                                &refs, &flags);
 196                 BUG_ON(ret);
 197                 BUG_ON(refs == 0);
 198         } else {
 199                 refs = 1;
 200                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 201                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 202                         flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
 203                 else
 204                         flags = 0;
 205         }
 206
 207         owner = btrfs_header_owner(buf);
 208         BUG_ON(!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) &&
 209                owner == BTRFS_TREE_RELOC_OBJECTID);
 210
 211         if (refs > 1) {
 212                 if ((owner == root->root_key.objectid ||
 213                      root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 214                     !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 215                         ret = btrfs_inc_ref(trans, root, buf, 1);
 216                         BUG_ON(ret);
 217
 218                         if (root->root_key.objectid ==
 219                             BTRFS_TREE_RELOC_OBJECTID) {
 220                                 ret = btrfs_dec_ref(trans, root, buf, 0);
 221                                 BUG_ON(ret);
 222                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 223                                 BUG_ON(ret);
 224                         }
 225                         new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 226                 } else {
 227
 228                         if (root->root_key.objectid ==
 229                             BTRFS_TREE_RELOC_OBJECTID)
 230                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 231                         else
 232                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 233                         BUG_ON(ret);
 234                 }
 235                 if (new_flags != 0) {
 236                         ret = btrfs_set_block_flags(trans, root, buf->start,
 237                                                     btrfs_header_level(buf),
 238                                                     new_flags);
 239                         BUG_ON(ret);
 240                 }
 241         } else {
 242                 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
 243                         if (root->root_key.objectid ==
 244                             BTRFS_TREE_RELOC_OBJECTID)
 245                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 246                         else
 247                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 248                         BUG_ON(ret);
 249                         ret = btrfs_dec_ref(trans, root, buf, 1);
 250                         BUG_ON(ret);
 251                 }
 252                 clean_tree_block(trans, root, buf);
 253         }
 254         return 0;
 255 }
 256
 257 int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 258                              struct btrfs_root *root,
 259                              struct extent_buffer *buf,
 260                              struct extent_buffer *parent, int parent_slot,
 261                              struct extent_buffer **cow_ret,
 262                              u64 search_start, u64 empty_size)
 263 {
 264         struct extent_buffer *cow;
 265         struct btrfs_disk_key disk_key;
 266         int level;
 267
 268         WARN_ON(root->ref_cows && trans->transid !=
 269                 root->fs_info->running_transaction->transid);
 270         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 271
 272         level = btrfs_header_level(buf);
 273
 274         if (level == 0)
 275                 btrfs_item_key(buf, &disk_key, 0);
 276         else
 277                 btrfs_node_key(buf, &disk_key, 0);
 278
 279         cow = btrfs_alloc_free_block(trans, root, buf->len,
 280                                      root->root_key.objectid, &disk_key,
 281                                      level, search_start, empty_size);
 282         if (IS_ERR(cow))
 283                 return PTR_ERR(cow);
 284
 285         copy_extent_buffer(cow, buf, 0, 0, cow->len);
 286         btrfs_set_header_bytenr(cow, cow->start);
 287         btrfs_set_header_generation(cow, trans->transid);
 288         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 289         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 290                                      BTRFS_HEADER_FLAG_RELOC);
 291         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 292                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 293         else
 294                 btrfs_set_header_owner(cow, root->root_key.objectid);
 295
 296         write_extent_buffer(cow, root->fs_info->fsid,
 297                             btrfs_header_fsid(), BTRFS_FSID_SIZE);
 298
 299         WARN_ON(!(buf->flags & EXTENT_BAD_TRANSID) &&
 300                 btrfs_header_generation(buf) > trans->transid);
 301
 302         update_ref_for_cow(trans, root, buf, cow);
 303
 304         if (buf == root->node) {
 305                 root->node = cow;
 306                 extent_buffer_get(cow);
 307
 308                 btrfs_free_extent(trans, root, buf->start, buf->len,
 309                                   0, root->root_key.objectid, level, 0);
 310                 free_extent_buffer(buf);
 311                 add_root_to_dirty_list(root);
 312         } else {
 313                 btrfs_set_node_blockptr(parent, parent_slot,
 314                                         cow->start);
 315                 WARN_ON(trans->transid == 0);
 316                 btrfs_set_node_ptr_generation(parent, parent_slot,
 317                                               trans->transid);
 318                 btrfs_mark_buffer_dirty(parent);
 319                 WARN_ON(btrfs_header_generation(parent) != trans->transid);
 320
 321                 btrfs_free_extent(trans, root, buf->start, buf->len,
 322                                   0, root->root_key.objectid, level, 1);
 323         }
 324         if (!list_empty(&buf->recow)) {
 325                 list_del_init(&buf->recow);
 326                 free_extent_buffer(buf);
 327         }
 328         free_extent_buffer(buf);
 329         btrfs_mark_buffer_dirty(cow);
 330         *cow_ret = cow;
 331         return 0;
 332 }
 333
 334 static inline int should_cow_block(struct btrfs_trans_handle *trans,
 335                                    struct btrfs_root *root,
 336                                    struct extent_buffer *buf)
 337 {
 338         if (btrfs_header_generation(buf) == trans->transid &&
 339             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
 340             !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
 341               btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 342                 return 0;
 343         return 1;
 344 }
 345
 346 int btrfs_cow_block(struct btrfs_trans_handle *trans,
 347                     struct btrfs_root *root, struct extent_buffer *buf,
 348                     struct extent_buffer *parent, int parent_slot,
 349                     struct extent_buffer **cow_ret)
 350 {
 351         u64 search_start;
 352         int ret;
 353         /*
 354         if (trans->transaction != root->fs_info->running_transaction) {
 355                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 356                        root->fs_info->running_transaction->transid);
 357                 WARN_ON(1);
 358         }
 359         */
 360         if (trans->transid != root->fs_info->generation) {
 361                 printk(KERN_CRIT "trans %llu running %llu\n",
 362                         (unsigned long long)trans->transid,
 363                         (unsigned long long)root->fs_info->generation);
 364                 WARN_ON(1);
 365         }
 366         if (!should_cow_block(trans, root, buf)) {
 367                 *cow_ret = buf;
 368                 return 0;
 369         }
 370
 371         search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
 372         ret = __btrfs_cow_block(trans, root, buf, parent,
 373                                  parent_slot, cow_ret, search_start, 0);
 374         return ret;
 375 }
 376
 377 int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
 378 {
 379         if (k1->objectid > k2->objectid)
 380                 return 1;
 381         if (k1->objectid < k2->objectid)
 382                 return -1;
 383         if (k1->type > k2->type)
 384                 return 1;
 385         if (k1->type < k2->type)
 386                 return -1;
 387         if (k1->offset > k2->offset)
 388                 return 1;
 389         if (k1->offset < k2->offset)
 390                 return -1;
 391         return 0;
 392 }
 393
 394 /*
 395  * compare two keys in a memcmp fashion
 396  */
 397 static int btrfs_comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 398 {
 399         struct btrfs_key k1;
 400
 401         btrfs_disk_key_to_cpu(&k1, disk);
 402         return btrfs_comp_cpu_keys(&k1, k2);
 403 }
 404
 405 /*
 406  * The leaf data grows from end-to-front in the node.
 407  * this returns the address of the start of the last item,
 408  * which is the stop of the leaf data stack
 409  */
 410 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 411                                          struct extent_buffer *leaf)
 412 {
 413         u32 nr = btrfs_header_nritems(leaf);
 414         if (nr == 0)
 415                 return BTRFS_LEAF_DATA_SIZE(root);
 416         return btrfs_item_offset_nr(leaf, nr - 1);
 417 }
 418
 419 enum btrfs_tree_block_status
 420 btrfs_check_node(struct btrfs_root *root, struct btrfs_disk_key *parent_key,
 421                  struct extent_buffer *buf)
 422 {
 423         int i;
 424         struct btrfs_key cpukey;
 425         struct btrfs_disk_key key;
 426         u32 nritems = btrfs_header_nritems(buf);
 427         enum btrfs_tree_block_status ret = BTRFS_TREE_BLOCK_INVALID_NRITEMS;
 428
 429         if (nritems == 0 || nritems > BTRFS_NODEPTRS_PER_BLOCK(root))
 430                 goto fail;
 431
 432         ret = BTRFS_TREE_BLOCK_INVALID_PARENT_KEY;
 433         if (parent_key && parent_key->type) {
 434                 btrfs_node_key(buf, &key, 0);
 435                 if (memcmp(parent_key, &key, sizeof(key)))
 436                         goto fail;
 437         }
 438         ret = BTRFS_TREE_BLOCK_BAD_KEY_ORDER;
 439         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 440                 btrfs_node_key(buf, &key, i);
 441                 btrfs_node_key_to_cpu(buf, &cpukey, i + 1);
 442                 if (btrfs_comp_keys(&key, &cpukey) >= 0)
 443                         goto fail;
 444         }
 445         return BTRFS_TREE_BLOCK_CLEAN;
 446 fail:
 447         if (btrfs_header_owner(buf) == BTRFS_EXTENT_TREE_OBJECTID) {
 448                 if (parent_key)
 449                         btrfs_disk_key_to_cpu(&cpukey, parent_key);
 450                 else
 451                         btrfs_node_key_to_cpu(buf, &cpukey, 0);
 452                 btrfs_add_corrupt_extent_record(root->fs_info, &cpukey,
 453                                                 buf->start, buf->len,
 454                                                 btrfs_header_level(buf));
 455         }
 456         return ret;
 457 }
 458
 459 enum btrfs_tree_block_status
 460 btrfs_check_leaf(struct btrfs_root *root, struct btrfs_disk_key *parent_key,
 461                  struct extent_buffer *buf)
 462 {
 463         int i;
 464         struct btrfs_key cpukey;
 465         struct btrfs_disk_key key;
 466         u32 nritems = btrfs_header_nritems(buf);
 467         enum btrfs_tree_block_status ret = BTRFS_TREE_BLOCK_INVALID_NRITEMS;
 468
 469         if (nritems * sizeof(struct btrfs_item) > buf->len)  {
 470                 fprintf(stderr, "invalid number of items %llu\n",
 471                         (unsigned long long)buf->start);
 472                 goto fail;
 473         }
 474
 475         if (btrfs_header_level(buf) != 0) {
 476                 ret = BTRFS_TREE_BLOCK_INVALID_LEVEL;
 477                 fprintf(stderr, "leaf is not a leaf %llu\n",
 478                        (unsigned long long)btrfs_header_bytenr(buf));
 479                 goto fail;
 480         }
 481         if (btrfs_leaf_free_space(root, buf) < 0) {
 482                 ret = BTRFS_TREE_BLOCK_INVALID_FREE_SPACE;
 483                 fprintf(stderr, "leaf free space incorrect %llu %d\n",
 484                         (unsigned long long)btrfs_header_bytenr(buf),
 485                         btrfs_leaf_free_space(root, buf));
 486                 goto fail;
 487         }
 488
 489         if (nritems == 0)
 490                 return BTRFS_TREE_BLOCK_CLEAN;
 491
 492         btrfs_item_key(buf, &key, 0);
 493         if (parent_key && parent_key->type &&
 494             memcmp(parent_key, &key, sizeof(key))) {
 495                 ret = BTRFS_TREE_BLOCK_INVALID_PARENT_KEY;
 496                 fprintf(stderr, "leaf parent key incorrect %llu\n",
 497                        (unsigned long long)btrfs_header_bytenr(buf));
 498                 goto fail;
 499         }
 500         for (i = 0; nritems > 1 && i < nritems - 1; i++) {
 501                 btrfs_item_key(buf, &key, i);
 502                 btrfs_item_key_to_cpu(buf, &cpukey, i + 1);
 503                 if (btrfs_comp_keys(&key, &cpukey) >= 0) {
 504                         ret = BTRFS_TREE_BLOCK_BAD_KEY_ORDER;
 505                         fprintf(stderr, "bad key ordering %d %d\n", i, i+1);
 506                         goto fail;
 507                 }
 508                 if (btrfs_item_offset_nr(buf, i) !=
 509                         btrfs_item_end_nr(buf, i + 1)) {
 510                         ret = BTRFS_TREE_BLOCK_INVALID_OFFSETS;
 511                         fprintf(stderr, "incorrect offsets %u %u\n",
 512                                 btrfs_item_offset_nr(buf, i),
 513                                 btrfs_item_end_nr(buf, i + 1));
 514                         goto fail;
 515                 }
 516                 if (i == 0 && btrfs_item_end_nr(buf, i) !=
 517                     BTRFS_LEAF_DATA_SIZE(root)) {
 518                         ret = BTRFS_TREE_BLOCK_INVALID_OFFSETS;
 519                         fprintf(stderr, "bad item end %u wanted %u\n",
 520                                 btrfs_item_end_nr(buf, i),
 521                                 (unsigned)BTRFS_LEAF_DATA_SIZE(root));
 522                         goto fail;
 523                 }
 524         }
 525
 526         for (i = 0; i < nritems; i++) {
 527                 if (btrfs_item_end_nr(buf, i) > BTRFS_LEAF_DATA_SIZE(root)) {
 528                         btrfs_item_key(buf, &key, 0);
 529                         btrfs_print_key(&key);
 530                         fflush(stdout);
 531                         ret = BTRFS_TREE_BLOCK_INVALID_OFFSETS;
 532                         fprintf(stderr, "slot end outside of leaf %llu > %llu\n",
 533                                 (unsigned long long)btrfs_item_end_nr(buf, i),
 534                                 (unsigned long long)BTRFS_LEAF_DATA_SIZE(root));
 535                         goto fail;
 536                 }
 537         }
 538
 539         return BTRFS_TREE_BLOCK_CLEAN;
 540 fail:
 541         if (btrfs_header_owner(buf) == BTRFS_EXTENT_TREE_OBJECTID) {
 542                 if (parent_key)
 543                         btrfs_disk_key_to_cpu(&cpukey, parent_key);
 544                 else
 545                         btrfs_item_key_to_cpu(buf, &cpukey, 0);
 546
 547                 btrfs_add_corrupt_extent_record(root->fs_info, &cpukey,
 548                                                 buf->start, buf->len, 0);
 549         }
 550         return ret;
 551 }
 552
 553 static int noinline check_block(struct btrfs_root *root,
 554                                 struct btrfs_path *path, int level)
 555 {
 556         struct btrfs_disk_key key;
 557         struct btrfs_disk_key *key_ptr = NULL;
 558         struct extent_buffer *parent;
 559         enum btrfs_tree_block_status ret;
 560
 561         if (path->skip_check_block)
 562                 return 0;
 563         if (path->nodes[level + 1]) {
 564                 parent = path->nodes[level + 1];
 565                 btrfs_node_key(parent, &key, path->slots[level + 1]);
 566                 key_ptr = &key;
 567         }
 568         if (level == 0)
 569                 ret =  btrfs_check_leaf(root, key_ptr, path->nodes[0]);
 570         else
 571                 ret = btrfs_check_node(root, key_ptr, path->nodes[level]);
 572         if (ret == BTRFS_TREE_BLOCK_CLEAN)
 573                 return 0;
 574         return -EIO;
 575 }
 576
 577 /*
 578  * search for key in the extent_buffer.  The items start at offset p,
 579  * and they are item_size apart.  There are 'max' items in p.
 580  *
 581  * the slot in the array is returned via slot, and it points to
 582  * the place where you would insert key if it is not found in
 583  * the array.
 584  *
 585  * slot may point to max if the key is bigger than all of the keys
 586  */
 587 static int generic_bin_search(struct extent_buffer *eb, unsigned long p,
 588                               int item_size, struct btrfs_key *key,
 589                               int max, int *slot)
 590 {
 591         int low = 0;
 592         int high = max;
 593         int mid;
 594         int ret;
 595         unsigned long offset;
 596         struct btrfs_disk_key *tmp;
 597
 598         while(low < high) {
 599                 mid = (low + high) / 2;
 600                 offset = p + mid * item_size;
 601
 602                 tmp = (struct btrfs_disk_key *)(eb->data + offset);
 603                 ret = btrfs_comp_keys(tmp, key);
 604
 605                 if (ret < 0)
 606                         low = mid + 1;
 607                 else if (ret > 0)
 608                         high = mid;
 609                 else {
 610                         *slot = mid;
 611                         return 0;
 612                 }
 613         }
 614         *slot = low;
 615         return 1;
 616 }
 617
 618 /*
 619  * simple bin_search frontend that does the right thing for
 620  * leaves vs nodes
 621  */
 622 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 623                       int level, int *slot)
 624 {
 625         if (level == 0)
 626                 return generic_bin_search(eb,
 627                                           offsetof(struct btrfs_leaf, items),
 628                                           sizeof(struct btrfs_item),
 629                                           key, btrfs_header_nritems(eb),
 630                                           slot);
 631         else
 632                 return generic_bin_search(eb,
 633                                           offsetof(struct btrfs_node, ptrs),
 634                                           sizeof(struct btrfs_key_ptr),
 635                                           key, btrfs_header_nritems(eb),
 636                                           slot);
 637 }
 638
 639 struct extent_buffer *read_node_slot(struct btrfs_root *root,
 640                                    struct extent_buffer *parent, int slot)
 641 {
 642         int level = btrfs_header_level(parent);
 643         if (slot < 0)
 644                 return NULL;
 645         if (slot >= btrfs_header_nritems(parent))
 646                 return NULL;
 647
 648         if (level == 0)
 649                 return NULL;
 650
 651         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 652                        root->nodesize,
 653                        btrfs_node_ptr_generation(parent, slot));
 654 }
 655
 656 static int balance_level(struct btrfs_trans_handle *trans,
 657                          struct btrfs_root *root,
 658                          struct btrfs_path *path, int level)
 659 {
 660         struct extent_buffer *right = NULL;
 661         struct extent_buffer *mid;
 662         struct extent_buffer *left = NULL;
 663         struct extent_buffer *parent = NULL;
 664         int ret = 0;
 665         int wret;
 666         int pslot;
 667         int orig_slot = path->slots[level];
 668         u64 orig_ptr;
 669
 670         if (level == 0)
 671                 return 0;
 672
 673         mid = path->nodes[level];
 674         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 675
 676         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 677
 678         if (level < BTRFS_MAX_LEVEL - 1) {
 679                 parent = path->nodes[level + 1];
 680                 pslot = path->slots[level + 1];
 681         }
 682
 683         /*
 684          * deal with the case where there is only one pointer in the root
 685          * by promoting the node below to a root
 686          */
 687         if (!parent) {
 688                 struct extent_buffer *child;
 689
 690                 if (btrfs_header_nritems(mid) != 1)
 691                         return 0;
 692
 693                 /* promote the child to a root */
 694                 child = read_node_slot(root, mid, 0);
 695                 BUG_ON(!extent_buffer_uptodate(child));
 696                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
 697                 BUG_ON(ret);
 698
 699                 root->node = child;
 700                 add_root_to_dirty_list(root);
 701                 path->nodes[level] = NULL;
 702                 clean_tree_block(trans, root, mid);
 703                 wait_on_tree_block_writeback(root, mid);
 704                 /* once for the path */
 705                 free_extent_buffer(mid);
 706
 707                 ret = btrfs_free_extent(trans, root, mid->start, mid->len,
 708                                         0, root->root_key.objectid,
 709                                         level, 1);
 710                 /* once for the root ptr */
 711                 free_extent_buffer(mid);
 712                 return ret;
 713         }
 714         if (btrfs_header_nritems(mid) >
 715             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 716                 return 0;
 717
 718         left = read_node_slot(root, parent, pslot - 1);
 719         if (extent_buffer_uptodate(left)) {
 720                 wret = btrfs_cow_block(trans, root, left,
 721                                        parent, pslot - 1, &left);
 722                 if (wret) {
 723                         ret = wret;
 724                         goto enospc;
 725                 }
 726         }
 727         right = read_node_slot(root, parent, pslot + 1);
 728         if (extent_buffer_uptodate(right)) {
 729                 wret = btrfs_cow_block(trans, root, right,
 730                                        parent, pslot + 1, &right);
 731                 if (wret) {
 732                         ret = wret;
 733                         goto enospc;
 734                 }
 735         }
 736
 737         /* first, try to make some room in the middle buffer */
 738         if (left) {
 739                 orig_slot += btrfs_header_nritems(left);
 740                 wret = push_node_left(trans, root, left, mid, 1);
 741                 if (wret < 0)
 742                         ret = wret;
 743         }
 744
 745         /*
 746          * then try to empty the right most buffer into the middle
 747          */
 748         if (right) {
 749                 wret = push_node_left(trans, root, mid, right, 1);
 750                 if (wret < 0 && wret != -ENOSPC)
 751                         ret = wret;
 752                 if (btrfs_header_nritems(right) == 0) {
 753                         u64 bytenr = right->start;
 754                         u32 blocksize = right->len;
 755
 756                         clean_tree_block(trans, root, right);
 757                         wait_on_tree_block_writeback(root, right);
 758                         free_extent_buffer(right);
 759                         right = NULL;
 760                         wret = btrfs_del_ptr(trans, root, path,
 761                                              level + 1, pslot + 1);
 762                         if (wret)
 763                                 ret = wret;
 764                         wret = btrfs_free_extent(trans, root, bytenr,
 765                                                  blocksize, 0,
 766                                                  root->root_key.objectid,
 767                                                  level, 0);
 768                         if (wret)
 769                                 ret = wret;
 770                 } else {
 771                         struct btrfs_disk_key right_key;
 772                         btrfs_node_key(right, &right_key, 0);
 773                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 774                         btrfs_mark_buffer_dirty(parent);
 775                 }
 776         }
 777         if (btrfs_header_nritems(mid) == 1) {
 778                 /*
 779                  * we're not allowed to leave a node with one item in the
 780                  * tree during a delete.  A deletion from lower in the tree
 781                  * could try to delete the only pointer in this node.
 782                  * So, pull some keys from the left.
 783                  * There has to be a left pointer at this point because
 784                  * otherwise we would have pulled some pointers from the
 785                  * right
 786                  */
 787                 BUG_ON(!left);
 788                 wret = balance_node_right(trans, root, mid, left);
 789                 if (wret < 0) {
 790                         ret = wret;
 791                         goto enospc;
 792                 }
 793                 if (wret == 1) {
 794                         wret = push_node_left(trans, root, left, mid, 1);
 795                         if (wret < 0)
 796                                 ret = wret;
 797                 }
 798                 BUG_ON(wret == 1);
 799         }
 800         if (btrfs_header_nritems(mid) == 0) {
 801                 /* we've managed to empty the middle node, drop it */
 802                 u64 bytenr = mid->start;
 803                 u32 blocksize = mid->len;
 804                 clean_tree_block(trans, root, mid);
 805                 wait_on_tree_block_writeback(root, mid);
 806                 free_extent_buffer(mid);
 807                 mid = NULL;
 808                 wret = btrfs_del_ptr(trans, root, path, level + 1, pslot);
 809                 if (wret)
 810                         ret = wret;
 811                 wret = btrfs_free_extent(trans, root, bytenr, blocksize,
 812                                          0, root->root_key.objectid,
 813                                          level, 0);
 814                 if (wret)
 815                         ret = wret;
 816         } else {
 817                 /* update the parent key to reflect our changes */
 818                 struct btrfs_disk_key mid_key;
 819                 btrfs_node_key(mid, &mid_key, 0);
 820                 btrfs_set_node_key(parent, &mid_key, pslot);
 821                 btrfs_mark_buffer_dirty(parent);
 822         }
 823
 824         /* update the path */
 825         if (left) {
 826                 if (btrfs_header_nritems(left) > orig_slot) {
 827                         extent_buffer_get(left);
 828                         path->nodes[level] = left;
 829                         path->slots[level + 1] -= 1;
 830                         path->slots[level] = orig_slot;
 831                         if (mid)
 832                                 free_extent_buffer(mid);
 833                 } else {
 834                         orig_slot -= btrfs_header_nritems(left);
 835                         path->slots[level] = orig_slot;
 836                 }
 837         }
 838         /* double check we haven't messed things up */
 839         check_block(root, path, level);
 840         if (orig_ptr !=
 841             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 842                 BUG();
 843 enospc:
 844         if (right)
 845                 free_extent_buffer(right);
 846         if (left)
 847                 free_extent_buffer(left);
 848         return ret;
 849 }
 850
 851 /* returns zero if the push worked, non-zero otherwise */
 852 static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
 853                                           struct btrfs_root *root,
 854                                           struct btrfs_path *path, int level)
 855 {
 856         struct extent_buffer *right = NULL;
 857         struct extent_buffer *mid;
 858         struct extent_buffer *left = NULL;
 859         struct extent_buffer *parent = NULL;
 860         int ret = 0;
 861         int wret;
 862         int pslot;
 863         int orig_slot = path->slots[level];
 864
 865         if (level == 0)
 866                 return 1;
 867
 868         mid = path->nodes[level];
 869         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 870
 871         if (level < BTRFS_MAX_LEVEL - 1) {
 872                 parent = path->nodes[level + 1];
 873                 pslot = path->slots[level + 1];
 874         }
 875
 876         if (!parent)
 877                 return 1;
 878
 879         left = read_node_slot(root, parent, pslot - 1);
 880
 881         /* first, try to make some room in the middle buffer */
 882         if (extent_buffer_uptodate(left)) {
 883                 u32 left_nr;
 884                 left_nr = btrfs_header_nritems(left);
 885                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 886                         wret = 1;
 887                 } else {
 888                         ret = btrfs_cow_block(trans, root, left, parent,
 889                                               pslot - 1, &left);
 890                         if (ret)
 891                                 wret = 1;
 892                         else {
 893                                 wret = push_node_left(trans, root,
 894                                                       left, mid, 0);
 895                         }
 896                 }
 897                 if (wret < 0)
 898                         ret = wret;
 899                 if (wret == 0) {
 900                         struct btrfs_disk_key disk_key;
 901                         orig_slot += left_nr;
 902                         btrfs_node_key(mid, &disk_key, 0);
 903                         btrfs_set_node_key(parent, &disk_key, pslot);
 904                         btrfs_mark_buffer_dirty(parent);
 905                         if (btrfs_header_nritems(left) > orig_slot) {
 906                                 path->nodes[level] = left;
 907                                 path->slots[level + 1] -= 1;
 908                                 path->slots[level] = orig_slot;
 909                                 free_extent_buffer(mid);
 910                         } else {
 911                                 orig_slot -=
 912                                         btrfs_header_nritems(left);
 913                                 path->slots[level] = orig_slot;
 914                                 free_extent_buffer(left);
 915                         }
 916                         return 0;
 917                 }
 918                 free_extent_buffer(left);
 919         }
 920         right= read_node_slot(root, parent, pslot + 1);
 921
 922         /*
 923          * then try to empty the right most buffer into the middle
 924          */
 925         if (extent_buffer_uptodate(right)) {
 926                 u32 right_nr;
 927                 right_nr = btrfs_header_nritems(right);
 928                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 929                         wret = 1;
 930                 } else {
 931                         ret = btrfs_cow_block(trans, root, right,
 932                                               parent, pslot + 1,
 933                                               &right);
 934                         if (ret)
 935                                 wret = 1;
 936                         else {
 937                                 wret = balance_node_right(trans, root,
 938                                                           right, mid);
 939                         }
 940                 }
 941                 if (wret < 0)
 942                         ret = wret;
 943                 if (wret == 0) {
 944                         struct btrfs_disk_key disk_key;
 945
 946                         btrfs_node_key(right, &disk_key, 0);
 947                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
 948                         btrfs_mark_buffer_dirty(parent);
 949
 950                         if (btrfs_header_nritems(mid) <= orig_slot) {
 951                                 path->nodes[level] = right;
 952                                 path->slots[level + 1] += 1;
 953                                 path->slots[level] = orig_slot -
 954                                         btrfs_header_nritems(mid);
 955                                 free_extent_buffer(mid);
 956                         } else {
 957                                 free_extent_buffer(right);
 958                         }
 959                         return 0;
 960                 }
 961                 free_extent_buffer(right);
 962         }
 963         return 1;
 964 }
 965
 966 /*
 967  * readahead one full node of leaves
 968  */
 969 void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 970                              int level, int slot, u64 objectid)
 971 {
 972         struct extent_buffer *node;
 973         struct btrfs_disk_key disk_key;
 974         u32 nritems;
 975         u64 search;
 976         u64 lowest_read;
 977         u64 highest_read;
 978         u64 nread = 0;
 979         int direction = path->reada;
 980         struct extent_buffer *eb;
 981         u32 nr;
 982         u32 blocksize;
 983         u32 nscan = 0;
 984
 985         if (level != 1)
 986                 return;
 987
 988         if (!path->nodes[level])
 989                 return;
 990
 991         node = path->nodes[level];
 992         search = btrfs_node_blockptr(node, slot);
 993         blocksize = root->nodesize;
 994         eb = btrfs_find_tree_block(root, search, blocksize);
 995         if (eb) {
 996                 free_extent_buffer(eb);
 997                 return;
 998         }
 999
1000         highest_read = search;
1001         lowest_read = search;
1002
1003         nritems = btrfs_header_nritems(node);
1004         nr = slot;
1005         while(1) {
1006                 if (direction < 0) {
1007                         if (nr == 0)
1008                                 break;
1009                         nr--;
1010                 } else if (direction > 0) {
1011                         nr++;
1012                         if (nr >= nritems)
1013                                 break;
1014                 }
1015                 if (path->reada < 0 && objectid) {
1016                         btrfs_node_key(node, &disk_key, nr);
1017                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1018                                 break;
1019                 }
1020                 search = btrfs_node_blockptr(node, nr);
1021                 if ((search >= lowest_read && search <= highest_read) ||
1022                     (search < lowest_read && lowest_read - search <= 32768) ||
1023                     (search > highest_read && search - highest_read <= 32768)) {
1024                         readahead_tree_block(root, search, blocksize,
1025                                      btrfs_node_ptr_generation(node, nr));
1026                         nread += blocksize;
1027                 }
1028                 nscan++;
1029                 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
1030                         break;
1031                 if(nread > (1024 * 1024) || nscan > 128)
1032                         break;
1033
1034                 if (search < lowest_read)
1035                         lowest_read = search;
1036                 if (search > highest_read)
1037                         highest_read = search;
1038         }
1039 }
1040
1041 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *found_path,
1042                 u64 iobjectid, u64 ioff, u8 key_type,
1043                 struct btrfs_key *found_key)
1044 {
1045         int ret;
1046         struct btrfs_key key;
1047         struct extent_buffer *eb;
1048         struct btrfs_path *path;
1049
1050         key.type = key_type;
1051         key.objectid = iobjectid;
1052         key.offset = ioff;
1053
1054         if (found_path == NULL) {
1055                 path = btrfs_alloc_path();
1056                 if (!path)
1057                         return -ENOMEM;
1058         } else
1059                 path = found_path;
1060
1061         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1062         if ((ret < 0) || (found_key == NULL))
1063                 goto out;
1064
1065         eb = path->nodes[0];
1066         if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1067                 ret = btrfs_next_leaf(fs_root, path);
1068                 if (ret)
1069                         goto out;
1070                 eb = path->nodes[0];
1071         }
1072
1073         btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1074         if (found_key->type != key.type ||
1075                         found_key->objectid != key.objectid) {
1076                 ret = 1;
1077                 goto out;
1078         }
1079
1080 out:
1081         if (path != found_path)
1082                 btrfs_free_path(path);
1083         return ret;
1084 }
1085
1086 /*
1087  * look for key in the tree.  path is filled in with nodes along the way
1088  * if key is found, we return zero and you can find the item in the leaf
1089  * level of the path (level 0)
1090  *
1091  * If the key isn't found, the path points to the slot where it should
1092  * be inserted, and 1 is returned.  If there are other errors during the
1093  * search a negative error number is returned.
1094  *
1095  * if ins_len > 0, nodes and leaves will be split as we walk down the
1096  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
1097  * possible)
1098  */
1099 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1100                       *root, struct btrfs_key *key, struct btrfs_path *p, int
1101                       ins_len, int cow)
1102 {
1103         struct extent_buffer *b;
1104         int slot;
1105         int ret;
1106         int level;
1107         int should_reada = p->reada;
1108         u8 lowest_level = 0;
1109
1110         lowest_level = p->lowest_level;
1111         WARN_ON(lowest_level && ins_len > 0);
1112         WARN_ON(p->nodes[0] != NULL);
1113         /*
1114         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
1115         */
1116 again:
1117         b = root->node;
1118         extent_buffer_get(b);
1119         while (b) {
1120                 level = btrfs_header_level(b);
1121                 if (cow) {
1122                         int wret;
1123                         wret = btrfs_cow_block(trans, root, b,
1124                                                p->nodes[level + 1],
1125                                                p->slots[level + 1],
1126                                                &b);
1127                         if (wret) {
1128                                 free_extent_buffer(b);
1129                                 return wret;
1130                         }
1131                 }
1132                 BUG_ON(!cow && ins_len);
1133                 if (level != btrfs_header_level(b))
1134                         WARN_ON(1);
1135                 level = btrfs_header_level(b);
1136                 p->nodes[level] = b;
1137                 ret = check_block(root, p, level);
1138                 if (ret)
1139                         return -1;
1140                 ret = bin_search(b, key, level, &slot);
1141                 if (level != 0) {
1142                         if (ret && slot > 0)
1143                                 slot -= 1;
1144                         p->slots[level] = slot;
1145                         if ((p->search_for_split || ins_len > 0) &&
1146                             btrfs_header_nritems(b) >=
1147                             BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
1148                                 int sret = split_node(trans, root, p, level);
1149                                 BUG_ON(sret > 0);
1150                                 if (sret)
1151                                         return sret;
1152                                 b = p->nodes[level];
1153                                 slot = p->slots[level];
1154                         } else if (ins_len < 0) {
1155                                 int sret = balance_level(trans, root, p,
1156                                                          level);
1157                                 if (sret)
1158                                         return sret;
1159                                 b = p->nodes[level];
1160                                 if (!b) {
1161                                         btrfs_release_path(p);
1162                                         goto again;
1163                                 }
1164                                 slot = p->slots[level];
1165                                 BUG_ON(btrfs_header_nritems(b) == 1);
1166                         }
1167                         /* this is only true while dropping a snapshot */
1168                         if (level == lowest_level)
1169                                 break;
1170
1171                         if (should_reada)
1172                                 reada_for_search(root, p, level, slot,
1173                                                  key->objectid);
1174
1175                         b = read_node_slot(root, b, slot);
1176                         if (!extent_buffer_uptodate(b))
1177                                 return -EIO;
1178                 } else {
1179                         p->slots[level] = slot;
1180                         if (ins_len > 0 &&
1181                             ins_len > btrfs_leaf_free_space(root, b)) {
1182                                 int sret = split_leaf(trans, root, key,
1183                                                       p, ins_len, ret == 0);
1184                                 BUG_ON(sret > 0);
1185                                 if (sret)
1186                                         return sret;
1187                         }
1188                         return ret;
1189                 }
1190         }
1191         return 1;
1192 }
1193
1194 /*
1195  * adjust the pointers going up the tree, starting at level
1196  * making sure the right key of each node is points to 'key'.
1197  * This is used after shifting pointers to the left, so it stops
1198  * fixing up pointers when a given leaf/node is not in slot 0 of the
1199  * higher levels
1200  */
1201 void btrfs_fixup_low_keys(struct btrfs_root *root, struct btrfs_path *path,
1202                           struct btrfs_disk_key *key, int level)
1203 {
1204         int i;
1205         struct extent_buffer *t;
1206
1207         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1208                 int tslot = path->slots[i];
1209                 if (!path->nodes[i])
1210                         break;
1211                 t = path->nodes[i];
1212                 btrfs_set_node_key(t, key, tslot);
1213                 btrfs_mark_buffer_dirty(path->nodes[i]);
1214                 if (tslot != 0)
1215                         break;
1216         }
1217 }
1218
1219 /*
1220  * update item key.
1221  *
1222  * This function isn't completely safe. It's the caller's responsibility
1223  * that the new key won't break the order
1224  */
1225 int btrfs_set_item_key_safe(struct btrfs_root *root, struct btrfs_path *path,
1226                             struct btrfs_key *new_key)
1227 {
1228         struct btrfs_disk_key disk_key;
1229         struct extent_buffer *eb;
1230         int slot;
1231
1232         eb = path->nodes[0];
1233         slot = path->slots[0];
1234         if (slot > 0) {
1235                 btrfs_item_key(eb, &disk_key, slot - 1);
1236                 if (btrfs_comp_keys(&disk_key, new_key) >= 0)
1237                         return -1;
1238         }
1239         if (slot < btrfs_header_nritems(eb) - 1) {
1240                 btrfs_item_key(eb, &disk_key, slot + 1);
1241                 if (btrfs_comp_keys(&disk_key, new_key) <= 0)
1242                         return -1;
1243         }
1244
1245         btrfs_cpu_key_to_disk(&disk_key, new_key);
1246         btrfs_set_item_key(eb, &disk_key, slot);
1247         btrfs_mark_buffer_dirty(eb);
1248         if (slot == 0)
1249                 btrfs_fixup_low_keys(root, path, &disk_key, 1);
1250         return 0;
1251 }
1252
1253 /*
1254  * update an item key without the safety checks.  This is meant to be called by
1255  * fsck only.
1256  */
1257 void btrfs_set_item_key_unsafe(struct btrfs_root *root,
1258                                struct btrfs_path *path,
1259                                struct btrfs_key *new_key)
1260 {
1261         struct btrfs_disk_key disk_key;
1262         struct extent_buffer *eb;
1263         int slot;
1264
1265         eb = path->nodes[0];
1266         slot = path->slots[0];
1267
1268         btrfs_cpu_key_to_disk(&disk_key, new_key);
1269         btrfs_set_item_key(eb, &disk_key, slot);
1270         btrfs_mark_buffer_dirty(eb);
1271         if (slot == 0)
1272                 btrfs_fixup_low_keys(root, path, &disk_key, 1);
1273 }
1274
1275 /*
1276  * try to push data from one node into the next node left in the
1277  * tree.
1278  *
1279  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1280  * error, and > 0 if there was no room in the left hand block.
1281  */
1282 static int push_node_left(struct btrfs_trans_handle *trans,
1283                           struct btrfs_root *root, struct extent_buffer *dst,
1284                           struct extent_buffer *src, int empty)
1285 {
1286         int push_items = 0;
1287         int src_nritems;
1288         int dst_nritems;
1289         int ret = 0;
1290
1291         src_nritems = btrfs_header_nritems(src);
1292         dst_nritems = btrfs_header_nritems(dst);
1293         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1294         WARN_ON(btrfs_header_generation(src) != trans->transid);
1295         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1296
1297         if (!empty && src_nritems <= 8)
1298                 return 1;
1299
1300         if (push_items <= 0) {
1301                 return 1;
1302         }
1303
1304         if (empty) {
1305                 push_items = min(src_nritems, push_items);
1306                 if (push_items < src_nritems) {
1307                         /* leave at least 8 pointers in the node if
1308                          * we aren't going to empty it
1309                          */
1310                         if (src_nritems - push_items < 8) {
1311                                 if (push_items <= 8)
1312                                         return 1;
1313                                 push_items -= 8;
1314                         }
1315                 }
1316         } else
1317                 push_items = min(src_nritems - 8, push_items);
1318
1319         copy_extent_buffer(dst, src,
1320                            btrfs_node_key_ptr_offset(dst_nritems),
1321                            btrfs_node_key_ptr_offset(0),
1322                            push_items * sizeof(struct btrfs_key_ptr));
1323
1324         if (push_items < src_nritems) {
1325                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1326                                       btrfs_node_key_ptr_offset(push_items),
1327                                       (src_nritems - push_items) *
1328                                       sizeof(struct btrfs_key_ptr));
1329         }
1330         btrfs_set_header_nritems(src, src_nritems - push_items);
1331         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1332         btrfs_mark_buffer_dirty(src);
1333         btrfs_mark_buffer_dirty(dst);
1334
1335         return ret;
1336 }
1337
1338 /*
1339  * try to push data from one node into the next node right in the
1340  * tree.
1341  *
1342  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1343  * error, and > 0 if there was no room in the right hand block.
1344  *
1345  * this will  only push up to 1/2 the contents of the left node over
1346  */
1347 static int balance_node_right(struct btrfs_trans_handle *trans,
1348                               struct btrfs_root *root,
1349                               struct extent_buffer *dst,
1350                               struct extent_buffer *src)
1351 {
1352         int push_items = 0;
1353         int max_push;
1354         int src_nritems;
1355         int dst_nritems;
1356         int ret = 0;
1357
1358         WARN_ON(btrfs_header_generation(src) != trans->transid);
1359         WARN_ON(btrfs_header_generation(dst) != trans->transid);
1360
1361         src_nritems = btrfs_header_nritems(src);
1362         dst_nritems = btrfs_header_nritems(dst);
1363         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1364         if (push_items <= 0) {
1365                 return 1;
1366         }
1367
1368         if (src_nritems < 4) {
1369                 return 1;
1370         }
1371
1372         max_push = src_nritems / 2 + 1;
1373         /* don't try to empty the node */
1374         if (max_push >= src_nritems) {
1375                 return 1;
1376         }
1377
1378         if (max_push < push_items)
1379                 push_items = max_push;
1380
1381         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1382                                       btrfs_node_key_ptr_offset(0),
1383                                       (dst_nritems) *
1384                                       sizeof(struct btrfs_key_ptr));
1385
1386         copy_extent_buffer(dst, src,
1387                            btrfs_node_key_ptr_offset(0),
1388                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1389                            push_items * sizeof(struct btrfs_key_ptr));
1390
1391         btrfs_set_header_nritems(src, src_nritems - push_items);
1392         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1393
1394         btrfs_mark_buffer_dirty(src);
1395         btrfs_mark_buffer_dirty(dst);
1396
1397         return ret;
1398 }
1399
1400 /*
1401  * helper function to insert a new root level in the tree.
1402  * A new node is allocated, and a single item is inserted to
1403  * point to the existing root
1404  *
1405  * returns zero on success or < 0 on failure.
1406  */
1407 static int noinline insert_new_root(struct btrfs_trans_handle *trans,
1408                            struct btrfs_root *root,
1409                            struct btrfs_path *path, int level)
1410 {
1411         u64 lower_gen;
1412         struct extent_buffer *lower;
1413         struct extent_buffer *c;
1414         struct extent_buffer *old;
1415         struct btrfs_disk_key lower_key;
1416
1417         BUG_ON(path->nodes[level]);
1418         BUG_ON(path->nodes[level-1] != root->node);
1419
1420         lower = path->nodes[level-1];
1421         if (level == 1)
1422                 btrfs_item_key(lower, &lower_key, 0);
1423         else
1424                 btrfs_node_key(lower, &lower_key, 0);
1425
1426         c = btrfs_alloc_free_block(trans, root, root->nodesize,
1427                                    root->root_key.objectid, &lower_key,
1428                                    level, root->node->start, 0);
1429
1430         if (IS_ERR(c))
1431                 return PTR_ERR(c);
1432
1433         memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
1434         btrfs_set_header_nritems(c, 1);
1435         btrfs_set_header_level(c, level);
1436         btrfs_set_header_bytenr(c, c->start);
1437         btrfs_set_header_generation(c, trans->transid);
1438         btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
1439         btrfs_set_header_owner(c, root->root_key.objectid);
1440
1441         write_extent_buffer(c, root->fs_info->fsid,
1442                             btrfs_header_fsid(), BTRFS_FSID_SIZE);
1443
1444         write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
1445                             btrfs_header_chunk_tree_uuid(c),
1446                             BTRFS_UUID_SIZE);
1447
1448         btrfs_set_node_key(c, &lower_key, 0);
1449         btrfs_set_node_blockptr(c, 0, lower->start);
1450         lower_gen = btrfs_header_generation(lower);
1451         WARN_ON(lower_gen != trans->transid);
1452
1453         btrfs_set_node_ptr_generation(c, 0, lower_gen);
1454
1455         btrfs_mark_buffer_dirty(c);
1456
1457         old = root->node;
1458         root->node = c;
1459
1460         /* the super has an extra ref to root->node */
1461         free_extent_buffer(old);
1462
1463         add_root_to_dirty_list(root);
1464         extent_buffer_get(c);
1465         path->nodes[level] = c;
1466         path->slots[level] = 0;
1467         return 0;
1468 }
1469
1470 /*
1471  * worker function to insert a single pointer in a node.
1472  * the node should have enough room for the pointer already
1473  *
1474  * slot and level indicate where you want the key to go, and
1475  * blocknr is the block the key points to.
1476  *
1477  * returns zero on success and < 0 on any error
1478  */
1479 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1480                       *root, struct btrfs_path *path, struct btrfs_disk_key
1481                       *key, u64 bytenr, int slot, int level)
1482 {
1483         struct extent_buffer *lower;
1484         int nritems;
1485
1486         BUG_ON(!path->nodes[level]);
1487         lower = path->nodes[level];
1488         nritems = btrfs_header_nritems(lower);
1489         if (slot > nritems)
1490                 BUG();
1491         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1492                 BUG();
1493         if (slot != nritems) {
1494                 memmove_extent_buffer(lower,
1495                               btrfs_node_key_ptr_offset(slot + 1),
1496                               btrfs_node_key_ptr_offset(slot),
1497                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1498         }
1499         btrfs_set_node_key(lower, key, slot);
1500         btrfs_set_node_blockptr(lower, slot, bytenr);
1501         WARN_ON(trans->transid == 0);
1502         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
1503         btrfs_set_header_nritems(lower, nritems + 1);
1504         btrfs_mark_buffer_dirty(lower);
1505         return 0;
1506 }
1507
1508 /*
1509  * split the node at the specified level in path in two.
1510  * The path is corrected to point to the appropriate node after the split
1511  *
1512  * Before splitting this tries to make some room in the node by pushing
1513  * left and right, if either one works, it returns right away.
1514  *
1515  * returns 0 on success and < 0 on failure
1516  */
1517 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1518                       *root, struct btrfs_path *path, int level)
1519 {
1520         struct extent_buffer *c;
1521         struct extent_buffer *split;
1522         struct btrfs_disk_key disk_key;
1523         int mid;
1524         int ret;
1525         int wret;
1526         u32 c_nritems;
1527
1528         c = path->nodes[level];
1529         WARN_ON(btrfs_header_generation(c) != trans->transid);
1530         if (c == root->node) {
1531                 /* trying to split the root, lets make a new one */
1532                 ret = insert_new_root(trans, root, path, level + 1);
1533                 if (ret)
1534                         return ret;
1535         } else {
1536                 ret = push_nodes_for_insert(trans, root, path, level);
1537                 c = path->nodes[level];
1538                 if (!ret && btrfs_header_nritems(c) <
1539                     BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
1540                         return 0;
1541                 if (ret < 0)
1542                         return ret;
1543         }
1544
1545         c_nritems = btrfs_header_nritems(c);
1546         mid = (c_nritems + 1) / 2;
1547         btrfs_node_key(c, &disk_key, mid);
1548
1549         split = btrfs_alloc_free_block(trans, root, root->nodesize,
1550                                         root->root_key.objectid,
1551                                         &disk_key, level, c->start, 0);
1552         if (IS_ERR(split))
1553                 return PTR_ERR(split);
1554
1555         memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
1556         btrfs_set_header_level(split, btrfs_header_level(c));
1557         btrfs_set_header_bytenr(split, split->start);
1558         btrfs_set_header_generation(split, trans->transid);
1559         btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
1560         btrfs_set_header_owner(split, root->root_key.objectid);
1561         write_extent_buffer(split, root->fs_info->fsid,
1562                             btrfs_header_fsid(), BTRFS_FSID_SIZE);
1563         write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
1564                             btrfs_header_chunk_tree_uuid(split),
1565                             BTRFS_UUID_SIZE);
1566
1567
1568         copy_extent_buffer(split, c,
1569                            btrfs_node_key_ptr_offset(0),
1570                            btrfs_node_key_ptr_offset(mid),
1571                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1572         btrfs_set_header_nritems(split, c_nritems - mid);
1573         btrfs_set_header_nritems(c, mid);
1574         ret = 0;
1575
1576         btrfs_mark_buffer_dirty(c);
1577         btrfs_mark_buffer_dirty(split);
1578
1579         wret = insert_ptr(trans, root, path, &disk_key, split->start,
1580                           path->slots[level + 1] + 1,
1581                           level + 1);
1582         if (wret)
1583                 ret = wret;
1584
1585         if (path->slots[level] >= mid) {
1586                 path->slots[level] -= mid;
1587                 free_extent_buffer(c);
1588                 path->nodes[level] = split;
1589                 path->slots[level + 1] += 1;
1590         } else {
1591                 free_extent_buffer(split);
1592         }
1593         return ret;
1594 }
1595
1596 /*
1597  * how many bytes are required to store the items in a leaf.  start
1598  * and nr indicate which items in the leaf to check.  This totals up the
1599  * space used both by the item structs and the item data
1600  */
1601 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1602 {
1603         int data_len;
1604         int nritems = btrfs_header_nritems(l);
1605         int end = min(nritems, start + nr) - 1;
1606
1607         if (!nr)
1608                 return 0;
1609         data_len = btrfs_item_end_nr(l, start);
1610         data_len = data_len - btrfs_item_offset_nr(l, end);
1611         data_len += sizeof(struct btrfs_item) * nr;
1612         WARN_ON(data_len < 0);
1613         return data_len;
1614 }
1615
1616 /*
1617  * The space between the end of the leaf items and
1618  * the start of the leaf data.  IOW, how much room
1619  * the leaf has left for both items and data
1620  */
1621 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1622 {
1623         u32 nodesize = (root ? BTRFS_LEAF_DATA_SIZE(root) : leaf->len);
1624         int nritems = btrfs_header_nritems(leaf);
1625         int ret;
1626         ret = nodesize - leaf_space_used(leaf, 0, nritems);
1627         if (ret < 0) {
1628                 printk("leaf free space ret %d, leaf data size %u, used %d nritems %d\n",
1629                        ret, nodesize, leaf_space_used(leaf, 0, nritems),
1630                        nritems);
1631         }
1632         return ret;
1633 }
1634
1635 /*
1636  * push some data in the path leaf to the right, trying to free up at
1637  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1638  *
1639  * returns 1 if the push failed because the other node didn't have enough
1640  * room, 0 if everything worked out and < 0 if there were major errors.
1641  */
1642 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1643                            *root, struct btrfs_path *path, int data_size,
1644                            int empty)
1645 {
1646         struct extent_buffer *left = path->nodes[0];
1647         struct extent_buffer *right;
1648         struct extent_buffer *upper;
1649         struct btrfs_disk_key disk_key;
1650         int slot;
1651         u32 i;
1652         int free_space;
1653         int push_space = 0;
1654         int push_items = 0;
1655         struct btrfs_item *item;
1656         u32 left_nritems;
1657         u32 nr;
1658         u32 right_nritems;
1659         u32 data_end;
1660         u32 this_item_size;
1661         int ret;
1662
1663         slot = path->slots[1];
1664         if (!path->nodes[1]) {
1665                 return 1;
1666         }
1667         upper = path->nodes[1];
1668         if (slot >= btrfs_header_nritems(upper) - 1)
1669                 return 1;
1670
1671         right = read_node_slot(root, upper, slot + 1);
1672         if (!extent_buffer_uptodate(right)) {
1673                 if (IS_ERR(right))
1674                         return PTR_ERR(right);
1675                 return -EIO;
1676         }
1677         free_space = btrfs_leaf_free_space(root, right);
1678         if (free_space < data_size) {
1679                 free_extent_buffer(right);
1680                 return 1;
1681         }
1682
1683         /* cow and double check */
1684         ret = btrfs_cow_block(trans, root, right, upper,
1685                               slot + 1, &right);
1686         if (ret) {
1687                 free_extent_buffer(right);
1688                 return 1;
1689         }
1690         free_space = btrfs_leaf_free_space(root, right);
1691         if (free_space < data_size) {
1692                 free_extent_buffer(right);
1693                 return 1;
1694         }
1695
1696         left_nritems = btrfs_header_nritems(left);
1697         if (left_nritems == 0) {
1698                 free_extent_buffer(right);
1699                 return 1;
1700         }
1701
1702         if (empty)
1703                 nr = 0;
1704         else
1705                 nr = 1;
1706
1707         i = left_nritems - 1;
1708         while (i >= nr) {
1709                 item = btrfs_item_nr(i);
1710
1711                 if (path->slots[0] == i)
1712                         push_space += data_size + sizeof(*item);
1713
1714                 this_item_size = btrfs_item_size(left, item);
1715                 if (this_item_size + sizeof(*item) + push_space > free_space)
1716                         break;
1717                 push_items++;
1718                 push_space += this_item_size + sizeof(*item);
1719                 if (i == 0)
1720                         break;
1721                 i--;
1722         }
1723
1724         if (push_items == 0) {
1725                 free_extent_buffer(right);
1726                 return 1;
1727         }
1728
1729         if (!empty && push_items == left_nritems)
1730                 WARN_ON(1);
1731
1732         /* push left to right */
1733         right_nritems = btrfs_header_nritems(right);
1734
1735         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1736         push_space -= leaf_data_end(root, left);
1737
1738         /* make room in the right data area */
1739         data_end = leaf_data_end(root, right);
1740         memmove_extent_buffer(right,
1741                               btrfs_leaf_data(right) + data_end - push_space,
1742                               btrfs_leaf_data(right) + data_end,
1743                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1744
1745         /* copy from the left data area */
1746         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1747                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1748                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1749                      push_space);
1750
1751         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1752                               btrfs_item_nr_offset(0),
1753                               right_nritems * sizeof(struct btrfs_item));
1754
1755         /* copy the items from left to right */
1756         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1757                    btrfs_item_nr_offset(left_nritems - push_items),
1758                    push_items * sizeof(struct btrfs_item));
1759
1760         /* update the item pointers */
1761         right_nritems += push_items;
1762         btrfs_set_header_nritems(right, right_nritems);
1763         push_space = BTRFS_LEAF_DATA_SIZE(root);
1764         for (i = 0; i < right_nritems; i++) {
1765                 item = btrfs_item_nr(i);
1766                 push_space -= btrfs_item_size(right, item);
1767                 btrfs_set_item_offset(right, item, push_space);
1768         }
1769
1770         left_nritems -= push_items;
1771         btrfs_set_header_nritems(left, left_nritems);
1772
1773         if (left_nritems)
1774                 btrfs_mark_buffer_dirty(left);
1775         btrfs_mark_buffer_dirty(right);
1776
1777         btrfs_item_key(right, &disk_key, 0);
1778         btrfs_set_node_key(upper, &disk_key, slot + 1);
1779         btrfs_mark_buffer_dirty(upper);
1780
1781         /* then fixup the leaf pointer in the path */
1782         if (path->slots[0] >= left_nritems) {
1783                 path->slots[0] -= left_nritems;
1784                 free_extent_buffer(path->nodes[0]);
1785                 path->nodes[0] = right;
1786                 path->slots[1] += 1;
1787         } else {
1788                 free_extent_buffer(right);
1789         }
1790         return 0;
1791 }
1792 /*
1793  * push some data in the path leaf to the left, trying to free up at
1794  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1795  */
1796 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1797                           *root, struct btrfs_path *path, int data_size,
1798                           int empty)
1799 {
1800         struct btrfs_disk_key disk_key;
1801         struct extent_buffer *right = path->nodes[0];
1802         struct extent_buffer *left;
1803         int slot;
1804         int i;
1805         int free_space;
1806         int push_space = 0;
1807         int push_items = 0;
1808         struct btrfs_item *item;
1809         u32 old_left_nritems;
1810         u32 right_nritems;
1811         u32 nr;
1812         int ret = 0;
1813         u32 this_item_size;
1814         u32 old_left_item_size;
1815
1816         slot = path->slots[1];
1817         if (slot == 0)
1818                 return 1;
1819         if (!path->nodes[1])
1820                 return 1;
1821
1822         right_nritems = btrfs_header_nritems(right);
1823         if (right_nritems == 0) {
1824                 return 1;
1825         }
1826
1827         left = read_node_slot(root, path->nodes[1], slot - 1);
1828         free_space = btrfs_leaf_free_space(root, left);
1829         if (free_space < data_size) {
1830                 free_extent_buffer(left);
1831                 return 1;
1832         }
1833
1834         /* cow and double check */
1835         ret = btrfs_cow_block(trans, root, left,
1836                               path->nodes[1], slot - 1, &left);
1837         if (ret) {
1838                 /* we hit -ENOSPC, but it isn't fatal here */
1839                 free_extent_buffer(left);
1840                 return 1;
1841         }
1842
1843         free_space = btrfs_leaf_free_space(root, left);
1844         if (free_space < data_size) {
1845                 free_extent_buffer(left);
1846                 return 1;
1847         }
1848
1849         if (empty)
1850                 nr = right_nritems;
1851         else
1852                 nr = right_nritems - 1;
1853
1854         for (i = 0; i < nr; i++) {
1855                 item = btrfs_item_nr(i);
1856
1857                 if (path->slots[0] == i)
1858                         push_space += data_size + sizeof(*item);
1859
1860                 this_item_size = btrfs_item_size(right, item);
1861                 if (this_item_size + sizeof(*item) + push_space > free_space)
1862                         break;
1863
1864                 push_items++;
1865                 push_space += this_item_size + sizeof(*item);
1866         }
1867
1868         if (push_items == 0) {
1869                 free_extent_buffer(left);
1870                 return 1;
1871         }
1872         if (!empty && push_items == btrfs_header_nritems(right))
1873                 WARN_ON(1);
1874
1875         /* push data from right to left */
1876         copy_extent_buffer(left, right,
1877                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1878                            btrfs_item_nr_offset(0),
1879                            push_items * sizeof(struct btrfs_item));
1880
1881         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1882                      btrfs_item_offset_nr(right, push_items -1);
1883
1884         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1885                      leaf_data_end(root, left) - push_space,
1886                      btrfs_leaf_data(right) +
1887                      btrfs_item_offset_nr(right, push_items - 1),
1888                      push_space);
1889         old_left_nritems = btrfs_header_nritems(left);
1890         BUG_ON(old_left_nritems == 0);
1891
1892         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
1893         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1894                 u32 ioff;
1895
1896                 item = btrfs_item_nr(i);
1897                 ioff = btrfs_item_offset(left, item);
1898                 btrfs_set_item_offset(left, item,
1899                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
1900         }
1901         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1902
1903         /* fixup right node */
1904         if (push_items > right_nritems) {
1905                 printk("push items %d nr %u\n", push_items, right_nritems);
1906                 WARN_ON(1);
1907         }
1908
1909         if (push_items < right_nritems) {
1910                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
1911                                                   leaf_data_end(root, right);
1912                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
1913                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
1914                                       btrfs_leaf_data(right) +
1915                                       leaf_data_end(root, right), push_space);
1916
1917                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1918                               btrfs_item_nr_offset(push_items),
1919                              (btrfs_header_nritems(right) - push_items) *
1920                              sizeof(struct btrfs_item));
1921         }
1922         right_nritems -= push_items;
1923         btrfs_set_header_nritems(right, right_nritems);
1924         push_space = BTRFS_LEAF_DATA_SIZE(root);
1925         for (i = 0; i < right_nritems; i++) {
1926                 item = btrfs_item_nr(i);
1927                 push_space = push_space - btrfs_item_size(right, item);
1928                 btrfs_set_item_offset(right, item, push_space);
1929         }
1930
1931         btrfs_mark_buffer_dirty(left);
1932         if (right_nritems)
1933                 btrfs_mark_buffer_dirty(right);
1934
1935         btrfs_item_key(right, &disk_key, 0);
1936         btrfs_fixup_low_keys(root, path, &disk_key, 1);
1937
1938         /* then fixup the leaf pointer in the path */
1939         if (path->slots[0] < push_items) {
1940                 path->slots[0] += old_left_nritems;
1941                 free_extent_buffer(path->nodes[0]);
1942                 path->nodes[0] = left;
1943                 path->slots[1] -= 1;
1944         } else {
1945                 free_extent_buffer(left);
1946                 path->slots[0] -= push_items;
1947         }
1948         BUG_ON(path->slots[0] < 0);
1949         return ret;
1950 }
1951
1952 /*
1953  * split the path's leaf in two, making sure there is at least data_size
1954  * available for the resulting leaf level of the path.
1955  *
1956  * returns 0 if all went well and < 0 on failure.
1957  */
1958 static noinline int copy_for_split(struct btrfs_trans_handle *trans,
1959                                struct btrfs_root *root,
1960                                struct btrfs_path *path,
1961                                struct extent_buffer *l,
1962                                struct extent_buffer *right,
1963                                int slot, int mid, int nritems)
1964 {
1965         int data_copy_size;
1966         int rt_data_off;
1967         int i;
1968         int ret = 0;
1969         int wret;
1970         struct btrfs_disk_key disk_key;
1971
1972         nritems = nritems - mid;
1973         btrfs_set_header_nritems(right, nritems);
1974         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
1975
1976         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
1977                            btrfs_item_nr_offset(mid),
1978                            nritems * sizeof(struct btrfs_item));
1979
1980         copy_extent_buffer(right, l,
1981                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1982                      data_copy_size, btrfs_leaf_data(l) +
1983                      leaf_data_end(root, l), data_copy_size);
1984
1985         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1986                       btrfs_item_end_nr(l, mid);
1987
1988         for (i = 0; i < nritems; i++) {
1989                 struct btrfs_item *item = btrfs_item_nr(i);
1990                 u32 ioff = btrfs_item_offset(right, item);
1991                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
1992         }
1993
1994         btrfs_set_header_nritems(l, mid);
1995         ret = 0;
1996         btrfs_item_key(right, &disk_key, 0);
1997         wret = insert_ptr(trans, root, path, &disk_key, right->start,
1998                           path->slots[1] + 1, 1);
1999         if (wret)
2000                 ret = wret;
2001
2002         btrfs_mark_buffer_dirty(right);
2003         btrfs_mark_buffer_dirty(l);
2004         BUG_ON(path->slots[0] != slot);
2005
2006         if (mid <= slot) {
2007                 free_extent_buffer(path->nodes[0]);
2008                 path->nodes[0] = right;
2009                 path->slots[0] -= mid;
2010                 path->slots[1] += 1;
2011         } else {
2012                 free_extent_buffer(right);
2013         }
2014
2015         BUG_ON(path->slots[0] < 0);
2016
2017         return ret;
2018 }
2019
2020 /*
2021  * split the path's leaf in two, making sure there is at least data_size
2022  * available for the resulting leaf level of the path.
2023  *
2024  * returns 0 if all went well and < 0 on failure.
2025  */
2026 static noinline int split_leaf(struct btrfs_trans_handle *trans,
2027                                struct btrfs_root *root,
2028                                struct btrfs_key *ins_key,
2029                                struct btrfs_path *path, int data_size,
2030                                int extend)
2031 {
2032         struct btrfs_disk_key disk_key;
2033         struct extent_buffer *l;
2034         u32 nritems;
2035         int mid;
2036         int slot;
2037         struct extent_buffer *right;
2038         int ret = 0;
2039         int wret;
2040         int split;
2041         int num_doubles = 0;
2042
2043         l = path->nodes[0];
2044         slot = path->slots[0];
2045         if (extend && data_size + btrfs_item_size_nr(l, slot) +
2046             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root))
2047                 return -EOVERFLOW;
2048
2049         /* first try to make some room by pushing left and right */
2050         if (data_size && ins_key->type != BTRFS_DIR_ITEM_KEY) {
2051                 wret = push_leaf_right(trans, root, path, data_size, 0);
2052                 if (wret < 0)
2053                         return wret;
2054                 if (wret) {
2055                         wret = push_leaf_left(trans, root, path, data_size, 0);
2056                         if (wret < 0)
2057                                 return wret;
2058                 }
2059                 l = path->nodes[0];
2060
2061                 /* did the pushes work? */
2062                 if (btrfs_leaf_free_space(root, l) >= data_size)
2063                         return 0;
2064         }
2065
2066         if (!path->nodes[1]) {
2067                 ret = insert_new_root(trans, root, path, 1);
2068                 if (ret)
2069                         return ret;
2070         }
2071 again:
2072         split = 1;
2073         l = path->nodes[0];
2074         slot = path->slots[0];
2075         nritems = btrfs_header_nritems(l);
2076         mid = (nritems + 1) / 2;
2077
2078         if (mid <= slot) {
2079                 if (nritems == 1 ||
2080                     leaf_space_used(l, mid, nritems - mid) + data_size >
2081                         BTRFS_LEAF_DATA_SIZE(root)) {
2082                         if (slot >= nritems) {
2083                                 split = 0;
2084                         } else {
2085                                 mid = slot;
2086                                 if (mid != nritems &&
2087                                     leaf_space_used(l, mid, nritems - mid) +
2088                                     data_size > BTRFS_LEAF_DATA_SIZE(root)) {
2089                                         split = 2;
2090                                 }
2091                         }
2092                 }
2093         } else {
2094                 if (leaf_space_used(l, 0, mid) + data_size >
2095                         BTRFS_LEAF_DATA_SIZE(root)) {
2096                         if (!extend && data_size && slot == 0) {
2097                                 split = 0;
2098                         } else if ((extend || !data_size) && slot == 0) {
2099                                 mid = 1;
2100                         } else {
2101                                 mid = slot;
2102                                 if (mid != nritems &&
2103                                     leaf_space_used(l, mid, nritems - mid) +
2104                                     data_size > BTRFS_LEAF_DATA_SIZE(root)) {
2105                                         split = 2 ;
2106                                 }
2107                         }
2108                 }
2109         }
2110
2111         if (split == 0)
2112                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
2113         else
2114                 btrfs_item_key(l, &disk_key, mid);
2115
2116         right = btrfs_alloc_free_block(trans, root, root->nodesize,
2117                                         root->root_key.objectid,
2118                                         &disk_key, 0, l->start, 0);
2119         if (IS_ERR(right)) {
2120                 BUG_ON(1);
2121                 return PTR_ERR(right);
2122         }
2123
2124         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
2125         btrfs_set_header_bytenr(right, right->start);
2126         btrfs_set_header_generation(right, trans->transid);
2127         btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
2128         btrfs_set_header_owner(right, root->root_key.objectid);
2129         btrfs_set_header_level(right, 0);
2130         write_extent_buffer(right, root->fs_info->fsid,
2131                             btrfs_header_fsid(), BTRFS_FSID_SIZE);
2132
2133         write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
2134                             btrfs_header_chunk_tree_uuid(right),
2135                             BTRFS_UUID_SIZE);
2136
2137         if (split == 0) {
2138                 if (mid <= slot) {
2139                         btrfs_set_header_nritems(right, 0);
2140                         wret = insert_ptr(trans, root, path,
2141                                           &disk_key, right->start,
2142                                           path->slots[1] + 1, 1);
2143                         if (wret)
2144                                 ret = wret;
2145
2146                         free_extent_buffer(path->nodes[0]);
2147                         path->nodes[0] = right;
2148                         path->slots[0] = 0;
2149                         path->slots[1] += 1;
2150                 } else {
2151                         btrfs_set_header_nritems(right, 0);
2152                         wret = insert_ptr(trans, root, path,
2153                                           &disk_key,
2154                                           right->start,
2155                                           path->slots[1], 1);
2156                         if (wret)
2157                                 ret = wret;
2158                         free_extent_buffer(path->nodes[0]);
2159                         path->nodes[0] = right;
2160                         path->slots[0] = 0;
2161                         if (path->slots[1] == 0) {
2162                                 btrfs_fixup_low_keys(root, path,
2163                                                      &disk_key, 1);
2164                         }
2165                 }
2166                 btrfs_mark_buffer_dirty(right);
2167                 return ret;
2168         }
2169
2170         ret = copy_for_split(trans, root, path, l, right, slot, mid, nritems);
2171         BUG_ON(ret);
2172
2173         if (split == 2) {
2174                 BUG_ON(num_doubles != 0);
2175                 num_doubles++;
2176                 goto again;
2177         }
2178
2179         return ret;
2180 }
2181
2182 /*
2183  * This function splits a single item into two items,
2184  * giving 'new_key' to the new item and splitting the
2185  * old one at split_offset (from the start of the item).
2186  *
2187  * The path may be released by this operation.  After
2188  * the split, the path is pointing to the old item.  The
2189  * new item is going to be in the same node as the old one.
2190  *
2191  * Note, the item being split must be smaller enough to live alone on
2192  * a tree block with room for one extra struct btrfs_item
2193  *
2194  * This allows us to split the item in place, keeping a lock on the
2195  * leaf the entire time.
2196  */
2197 int btrfs_split_item(struct btrfs_trans_handle *trans,
2198                      struct btrfs_root *root,
2199                      struct btrfs_path *path,
2200                      struct btrfs_key *new_key,
2201                      unsigned long split_offset)
2202 {
2203         u32 item_size;
2204         struct extent_buffer *leaf;
2205         struct btrfs_key orig_key;
2206         struct btrfs_item *item;
2207         struct btrfs_item *new_item;
2208         int ret = 0;
2209         int slot;
2210         u32 nritems;
2211         u32 orig_offset;
2212         struct btrfs_disk_key disk_key;
2213         char *buf;
2214
2215         leaf = path->nodes[0];
2216         btrfs_item_key_to_cpu(leaf, &orig_key, path->slots[0]);
2217         if (btrfs_leaf_free_space(root, leaf) >= sizeof(struct btrfs_item))
2218                 goto split;
2219
2220         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
2221         btrfs_release_path(path);
2222
2223         path->search_for_split = 1;
2224
2225         ret = btrfs_search_slot(trans, root, &orig_key, path, 0, 1);
2226         path->search_for_split = 0;
2227
2228         /* if our item isn't there or got smaller, return now */
2229         if (ret != 0 || item_size != btrfs_item_size_nr(path->nodes[0],
2230                                                         path->slots[0])) {
2231                 return -EAGAIN;
2232         }
2233
2234         ret = split_leaf(trans, root, &orig_key, path, 0, 0);
2235         BUG_ON(ret);
2236
2237         BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
2238         leaf = path->nodes[0];
2239
2240 split:
2241         item = btrfs_item_nr(path->slots[0]);
2242         orig_offset = btrfs_item_offset(leaf, item);
2243         item_size = btrfs_item_size(leaf, item);
2244
2245
2246         buf = kmalloc(item_size, GFP_NOFS);
2247         BUG_ON(!buf);
2248         read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
2249                             path->slots[0]), item_size);
2250         slot = path->slots[0] + 1;
2251         leaf = path->nodes[0];
2252
2253         nritems = btrfs_header_nritems(leaf);
2254
2255         if (slot != nritems) {
2256                 /* shift the items */
2257                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
2258                               btrfs_item_nr_offset(slot),
2259                               (nritems - slot) * sizeof(struct btrfs_item));
2260
2261         }
2262
2263         btrfs_cpu_key_to_disk(&disk_key, new_key);
2264         btrfs_set_item_key(leaf, &disk_key, slot);
2265
2266         new_item = btrfs_item_nr(slot);
2267
2268         btrfs_set_item_offset(leaf, new_item, orig_offset);
2269         btrfs_set_item_size(leaf, new_item, item_size - split_offset);
2270
2271         btrfs_set_item_offset(leaf, item,
2272                               orig_offset + item_size - split_offset);
2273         btrfs_set_item_size(leaf, item, split_offset);
2274
2275         btrfs_set_header_nritems(leaf, nritems + 1);
2276
2277         /* write the data for the start of the original item */
2278         write_extent_buffer(leaf, buf,
2279                             btrfs_item_ptr_offset(leaf, path->slots[0]),
2280                             split_offset);
2281
2282         /* write the data for the new item */
2283         write_extent_buffer(leaf, buf + split_offset,
2284                             btrfs_item_ptr_offset(leaf, slot),
2285                             item_size - split_offset);
2286         btrfs_mark_buffer_dirty(leaf);
2287
2288         ret = 0;
2289         if (btrfs_leaf_free_space(root, leaf) < 0) {
2290                 btrfs_print_leaf(root, leaf);
2291                 BUG();
2292         }
2293         kfree(buf);
2294         return ret;
2295 }
2296
2297 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
2298                         struct btrfs_root *root,
2299                         struct btrfs_path *path,
2300                         u32 new_size, int from_end)
2301 {
2302         int ret = 0;
2303         int slot;
2304         struct extent_buffer *leaf;
2305         struct btrfs_item *item;
2306         u32 nritems;
2307         unsigned int data_end;
2308         unsigned int old_data_start;
2309         unsigned int old_size;
2310         unsigned int size_diff;
2311         int i;
2312
2313         leaf = path->nodes[0];
2314         slot = path->slots[0];
2315
2316         old_size = btrfs_item_size_nr(leaf, slot);
2317         if (old_size == new_size)
2318                 return 0;
2319
2320         nritems = btrfs_header_nritems(leaf);
2321         data_end = leaf_data_end(root, leaf);
2322
2323         old_data_start = btrfs_item_offset_nr(leaf, slot);
2324
2325         size_diff = old_size - new_size;
2326
2327         BUG_ON(slot < 0);
2328         BUG_ON(slot >= nritems);
2329
2330         /*
2331          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2332          */
2333         /* first correct the data pointers */
2334         for (i = slot; i < nritems; i++) {
2335                 u32 ioff;
2336                 item = btrfs_item_nr(i);
2337                 ioff = btrfs_item_offset(leaf, item);
2338                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2339         }
2340
2341         /* shift the data */
2342         if (from_end) {
2343                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2344                               data_end + size_diff, btrfs_leaf_data(leaf) +
2345                               data_end, old_data_start + new_size - data_end);
2346         } else {
2347                 struct btrfs_disk_key disk_key;
2348                 u64 offset;
2349
2350                 btrfs_item_key(leaf, &disk_key, slot);
2351
2352                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
2353                         unsigned long ptr;
2354                         struct btrfs_file_extent_item *fi;
2355
2356                         fi = btrfs_item_ptr(leaf, slot,
2357                                             struct btrfs_file_extent_item);
2358                         fi = (struct btrfs_file_extent_item *)(
2359                              (unsigned long)fi - size_diff);
2360
2361                         if (btrfs_file_extent_type(leaf, fi) ==
2362                             BTRFS_FILE_EXTENT_INLINE) {
2363                                 ptr = btrfs_item_ptr_offset(leaf, slot);
2364                                 memmove_extent_buffer(leaf, ptr,
2365                                         (unsigned long)fi,
2366                                         offsetof(struct btrfs_file_extent_item,
2367                                                  disk_bytenr));
2368                         }
2369                 }
2370
2371                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2372                               data_end + size_diff, btrfs_leaf_data(leaf) +
2373                               data_end, old_data_start - data_end);
2374
2375                 offset = btrfs_disk_key_offset(&disk_key);
2376                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
2377                 btrfs_set_item_key(leaf, &disk_key, slot);
2378                 if (slot == 0)
2379                         btrfs_fixup_low_keys(root, path, &disk_key, 1);
2380         }
2381
2382         item = btrfs_item_nr(slot);
2383         btrfs_set_item_size(leaf, item, new_size);
2384         btrfs_mark_buffer_dirty(leaf);
2385
2386         ret = 0;
2387         if (btrfs_leaf_free_space(root, leaf) < 0) {
2388                 btrfs_print_leaf(root, leaf);
2389                 BUG();
2390         }
2391         return ret;
2392 }
2393
2394 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2395                       struct btrfs_root *root, struct btrfs_path *path,
2396                       u32 data_size)
2397 {
2398         int ret = 0;
2399         int slot;
2400         struct extent_buffer *leaf;
2401         struct btrfs_item *item;
2402         u32 nritems;
2403         unsigned int data_end;
2404         unsigned int old_data;
2405         unsigned int old_size;
2406         int i;
2407
2408         leaf = path->nodes[0];
2409
2410         nritems = btrfs_header_nritems(leaf);
2411         data_end = leaf_data_end(root, leaf);
2412
2413         if (btrfs_leaf_free_space(root, leaf) < data_size) {
2414                 btrfs_print_leaf(root, leaf);
2415                 BUG();
2416         }
2417         slot = path->slots[0];
2418         old_data = btrfs_item_end_nr(leaf, slot);
2419
2420         BUG_ON(slot < 0);
2421         if (slot >= nritems) {
2422                 btrfs_print_leaf(root, leaf);
2423                 printk("slot %d too large, nritems %d\n", slot, nritems);
2424                 BUG_ON(1);
2425         }
2426
2427         /*
2428          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2429          */
2430         /* first correct the data pointers */
2431         for (i = slot; i < nritems; i++) {
2432                 u32 ioff;
2433                 item = btrfs_item_nr(i);
2434                 ioff = btrfs_item_offset(leaf, item);
2435                 btrfs_set_item_offset(leaf, item, ioff - data_size);
2436         }
2437
2438         /* shift the data */
2439         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2440                       data_end - data_size, btrfs_leaf_data(leaf) +
2441                       data_end, old_data - data_end);
2442
2443         data_end = old_data;
2444         old_size = btrfs_item_size_nr(leaf, slot);
2445         item = btrfs_item_nr(slot);
2446         btrfs_set_item_size(leaf, item, old_size + data_size);
2447         btrfs_mark_buffer_dirty(leaf);
2448
2449         ret = 0;
2450         if (btrfs_leaf_free_space(root, leaf) < 0) {
2451                 btrfs_print_leaf(root, leaf);
2452                 BUG();
2453         }
2454         return ret;
2455 }
2456
2457 /*
2458  * Given a key and some data, insert an item into the tree.
2459  * This does all the path init required, making room in the tree if needed.
2460  */
2461 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
2462                             struct btrfs_root *root,
2463                             struct btrfs_path *path,
2464                             struct btrfs_key *cpu_key, u32 *data_size,
2465                             int nr)
2466 {
2467         struct extent_buffer *leaf;
2468         struct btrfs_item *item;
2469         int ret = 0;
2470         int slot;
2471         int i;
2472         u32 nritems;
2473         u32 total_size = 0;
2474         u32 total_data = 0;
2475         unsigned int data_end;
2476         struct btrfs_disk_key disk_key;
2477
2478         for (i = 0; i < nr; i++) {
2479                 total_data += data_size[i];
2480         }
2481
2482         /* create a root if there isn't one */
2483         if (!root->node)
2484                 BUG();
2485
2486         total_size = total_data + nr * sizeof(struct btrfs_item);
2487         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
2488         if (ret == 0) {
2489                 return -EEXIST;
2490         }
2491         if (ret < 0)
2492                 goto out;
2493
2494         leaf = path->nodes[0];
2495
2496         nritems = btrfs_header_nritems(leaf);
2497         data_end = leaf_data_end(root, leaf);
2498
2499         if (btrfs_leaf_free_space(root, leaf) < total_size) {
2500                 btrfs_print_leaf(root, leaf);
2501                 printk("not enough freespace need %u have %d\n",
2502                        total_size, btrfs_leaf_free_space(root, leaf));
2503                 BUG();
2504         }
2505
2506         slot = path->slots[0];
2507         BUG_ON(slot < 0);
2508
2509         if (slot != nritems) {
2510                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2511
2512                 if (old_data < data_end) {
2513                         btrfs_print_leaf(root, leaf);
2514                         printk("slot %d old_data %d data_end %d\n",
2515                                slot, old_data, data_end);
2516                         BUG_ON(1);
2517                 }
2518                 /*
2519                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2520                  */
2521                 /* first correct the data pointers */
2522                 for (i = slot; i < nritems; i++) {
2523                         u32 ioff;
2524
2525                         item = btrfs_item_nr(i);
2526                         ioff = btrfs_item_offset(leaf, item);
2527                         btrfs_set_item_offset(leaf, item, ioff - total_data);
2528                 }
2529
2530                 /* shift the items */
2531                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
2532                               btrfs_item_nr_offset(slot),
2533                               (nritems - slot) * sizeof(struct btrfs_item));
2534
2535                 /* shift the data */
2536                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2537                               data_end - total_data, btrfs_leaf_data(leaf) +
2538                               data_end, old_data - data_end);
2539                 data_end = old_data;
2540         }
2541
2542         /* setup the item for the new data */
2543         for (i = 0; i < nr; i++) {
2544                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
2545                 btrfs_set_item_key(leaf, &disk_key, slot + i);
2546                 item = btrfs_item_nr(slot + i);
2547                 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
2548                 data_end -= data_size[i];
2549                 btrfs_set_item_size(leaf, item, data_size[i]);
2550         }
2551         btrfs_set_header_nritems(leaf, nritems + nr);
2552         btrfs_mark_buffer_dirty(leaf);
2553
2554         ret = 0;
2555         if (slot == 0) {
2556                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2557                 btrfs_fixup_low_keys(root, path, &disk_key, 1);
2558         }
2559
2560         if (btrfs_leaf_free_space(root, leaf) < 0) {
2561                 btrfs_print_leaf(root, leaf);
2562                 BUG();
2563         }
2564
2565 out:
2566         return ret;
2567 }
2568
2569 /*
2570  * Given a key and some data, insert an item into the tree.
2571  * This does all the path init required, making room in the tree if needed.
2572  */
2573 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2574                       *root, struct btrfs_key *cpu_key, void *data, u32
2575                       data_size)
2576 {
2577         int ret = 0;
2578         struct btrfs_path *path;
2579         struct extent_buffer *leaf;
2580         unsigned long ptr;
2581
2582         path = btrfs_alloc_path();
2583         if (!path)
2584                 return -ENOMEM;
2585
2586         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2587         if (!ret) {
2588                 leaf = path->nodes[0];
2589                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2590                 write_extent_buffer(leaf, data, ptr, data_size);
2591                 btrfs_mark_buffer_dirty(leaf);
2592         }
2593         btrfs_free_path(path);
2594         return ret;
2595 }
2596
2597 /*
2598  * delete the pointer from a given node.
2599  *
2600  * If the delete empties a node, the node is removed from the tree,
2601  * continuing all the way the root if required.  The root is converted into
2602  * a leaf if all the nodes are emptied.
2603  */
2604 int btrfs_del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2605                    struct btrfs_path *path, int level, int slot)
2606 {
2607         struct extent_buffer *parent = path->nodes[level];
2608         u32 nritems;
2609         int ret = 0;
2610
2611         nritems = btrfs_header_nritems(parent);
2612         if (slot != nritems -1) {
2613                 memmove_extent_buffer(parent,
2614                               btrfs_node_key_ptr_offset(slot),
2615                               btrfs_node_key_ptr_offset(slot + 1),
2616                               sizeof(struct btrfs_key_ptr) *
2617                               (nritems - slot - 1));
2618         }
2619         nritems--;
2620         btrfs_set_header_nritems(parent, nritems);
2621         if (nritems == 0 && parent == root->node) {
2622                 BUG_ON(btrfs_header_level(root->node) != 1);
2623                 /* just turn the root into a leaf and break */
2624                 btrfs_set_header_level(root->node, 0);
2625         } else if (slot == 0) {
2626                 struct btrfs_disk_key disk_key;
2627
2628                 btrfs_node_key(parent, &disk_key, 0);
2629                 btrfs_fixup_low_keys(root, path, &disk_key, level + 1);
2630         }
2631         btrfs_mark_buffer_dirty(parent);
2632         return ret;
2633 }
2634
2635 /*
2636  * a helper function to delete the leaf pointed to by path->slots[1] and
2637  * path->nodes[1].
2638  *
2639  * This deletes the pointer in path->nodes[1] and frees the leaf
2640  * block extent.  zero is returned if it all worked out, < 0 otherwise.
2641  *
2642  * The path must have already been setup for deleting the leaf, including
2643  * all the proper balancing.  path->nodes[1] must be locked.
2644  */
2645 static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
2646                                    struct btrfs_root *root,
2647                                    struct btrfs_path *path,
2648                                    struct extent_buffer *leaf)
2649 {
2650         int ret;
2651
2652         WARN_ON(btrfs_header_generation(leaf) != trans->transid);
2653         ret = btrfs_del_ptr(trans, root, path, 1, path->slots[1]);
2654         if (ret)
2655                 return ret;
2656
2657         ret = btrfs_free_extent(trans, root, leaf->start, leaf->len,
2658                                 0, root->root_key.objectid, 0, 0);
2659         return ret;
2660 }
2661
2662 /*
2663  * delete the item at the leaf level in path.  If that empties
2664  * the leaf, remove it from the tree
2665  */
2666 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2667                     struct btrfs_path *path, int slot, int nr)
2668 {
2669         struct extent_buffer *leaf;
2670         struct btrfs_item *item;
2671         int last_off;
2672         int dsize = 0;
2673         int ret = 0;
2674         int wret;
2675         int i;
2676         u32 nritems;
2677
2678         leaf = path->nodes[0];
2679         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
2680
2681         for (i = 0; i < nr; i++)
2682                 dsize += btrfs_item_size_nr(leaf, slot + i);
2683
2684         nritems = btrfs_header_nritems(leaf);
2685
2686         if (slot + nr != nritems) {
2687                 int data_end = leaf_data_end(root, leaf);
2688
2689                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2690                               data_end + dsize,
2691                               btrfs_leaf_data(leaf) + data_end,
2692                               last_off - data_end);
2693
2694                 for (i = slot + nr; i < nritems; i++) {
2695                         u32 ioff;
2696
2697                         item = btrfs_item_nr(i);
2698                         ioff = btrfs_item_offset(leaf, item);
2699                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2700                 }
2701
2702                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2703                               btrfs_item_nr_offset(slot + nr),
2704                               sizeof(struct btrfs_item) *
2705                               (nritems - slot - nr));
2706         }
2707         btrfs_set_header_nritems(leaf, nritems - nr);
2708         nritems -= nr;
2709
2710         /* delete the leaf if we've emptied it */
2711         if (nritems == 0) {
2712                 if (leaf == root->node) {
2713                         btrfs_set_header_level(leaf, 0);
2714                 } else {
2715                         clean_tree_block(trans, root, leaf);
2716                         wait_on_tree_block_writeback(root, leaf);
2717
2718                         wret = btrfs_del_leaf(trans, root, path, leaf);
2719                         BUG_ON(ret);
2720                         if (wret)
2721                                 ret = wret;
2722                 }
2723         } else {
2724                 int used = leaf_space_used(leaf, 0, nritems);
2725                 if (slot == 0) {
2726                         struct btrfs_disk_key disk_key;
2727
2728                         btrfs_item_key(leaf, &disk_key, 0);
2729                         btrfs_fixup_low_keys(root, path, &disk_key, 1);
2730                 }
2731
2732                 /* delete the leaf if it is mostly empty */
2733                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 4) {
2734                         /* push_leaf_left fixes the path.
2735                          * make sure the path still points to our leaf
2736                          * for possible call to del_ptr below
2737                          */
2738                         slot = path->slots[1];
2739                         extent_buffer_get(leaf);
2740
2741                         wret = push_leaf_left(trans, root, path, 1, 1);
2742                         if (wret < 0 && wret != -ENOSPC)
2743                                 ret = wret;
2744
2745                         if (path->nodes[0] == leaf &&
2746                             btrfs_header_nritems(leaf)) {
2747                                 wret = push_leaf_right(trans, root, path, 1, 1);
2748                                 if (wret < 0 && wret != -ENOSPC)
2749                                         ret = wret;
2750                         }
2751
2752                         if (btrfs_header_nritems(leaf) == 0) {
2753                                 clean_tree_block(trans, root, leaf);
2754                                 wait_on_tree_block_writeback(root, leaf);
2755
2756                                 path->slots[1] = slot;
2757                                 ret = btrfs_del_leaf(trans, root, path, leaf);
2758                                 BUG_ON(ret);
2759                                 free_extent_buffer(leaf);
2760
2761                         } else {
2762                                 btrfs_mark_buffer_dirty(leaf);
2763                                 free_extent_buffer(leaf);
2764                         }
2765                 } else {
2766                         btrfs_mark_buffer_dirty(leaf);
2767                 }
2768         }
2769         return ret;
2770 }
2771
2772 /*
2773  * walk up the tree as far as required to find the previous leaf.
2774  * returns 0 if it found something or 1 if there are no lesser leaves.
2775  * returns < 0 on io errors.
2776  */
2777 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2778 {
2779         int slot;
2780         int level = 1;
2781         struct extent_buffer *c;
2782         struct extent_buffer *next = NULL;
2783
2784         while(level < BTRFS_MAX_LEVEL) {
2785                 if (!path->nodes[level])
2786                         return 1;
2787
2788                 slot = path->slots[level];
2789                 c = path->nodes[level];
2790                 if (slot == 0) {
2791                         level++;
2792                         if (level == BTRFS_MAX_LEVEL)
2793                                 return 1;
2794                         continue;
2795                 }
2796                 slot--;
2797
2798                 next = read_node_slot(root, c, slot);
2799                 if (!extent_buffer_uptodate(next)) {
2800                         if (IS_ERR(next))
2801                                 return PTR_ERR(next);
2802                         return -EIO;
2803                 }
2804                 break;
2805         }
2806         path->slots[level] = slot;
2807         while(1) {
2808                 level--;
2809                 c = path->nodes[level];
2810                 free_extent_buffer(c);
2811                 slot = btrfs_header_nritems(next);
2812                 if (slot != 0)
2813                         slot--;
2814                 path->nodes[level] = next;
2815                 path->slots[level] = slot;
2816                 if (!level)
2817                         break;
2818                 next = read_node_slot(root, next, slot);
2819                 if (!extent_buffer_uptodate(next)) {
2820                         if (IS_ERR(next))
2821                                 return PTR_ERR(next);
2822                         return -EIO;
2823                 }
2824         }
2825         return 0;
2826 }
2827
2828 /*
2829  * walk up the tree as far as required to find the next leaf.
2830  * returns 0 if it found something or 1 if there are no greater leaves.
2831  * returns < 0 on io errors.
2832  */
2833 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2834 {
2835         int slot;
2836         int level = 1;
2837         struct extent_buffer *c;
2838         struct extent_buffer *next = NULL;
2839
2840         while(level < BTRFS_MAX_LEVEL) {
2841                 if (!path->nodes[level])
2842                         return 1;
2843
2844                 slot = path->slots[level] + 1;
2845                 c = path->nodes[level];
2846                 if (slot >= btrfs_header_nritems(c)) {
2847                         level++;
2848                         if (level == BTRFS_MAX_LEVEL)
2849                                 return 1;
2850                         continue;
2851                 }
2852
2853                 if (path->reada)
2854                         reada_for_search(root, path, level, slot, 0);
2855
2856                 next = read_node_slot(root, c, slot);
2857                 if (!extent_buffer_uptodate(next))
2858                         return -EIO;
2859                 break;
2860         }
2861         path->slots[level] = slot;
2862         while(1) {
2863                 level--;
2864                 c = path->nodes[level];
2865                 free_extent_buffer(c);
2866                 path->nodes[level] = next;
2867                 path->slots[level] = 0;
2868                 if (!level)
2869                         break;
2870                 if (path->reada)
2871                         reada_for_search(root, path, level, 0, 0);
2872                 next = read_node_slot(root, next, 0);
2873                 if (!extent_buffer_uptodate(next))
2874                         return -EIO;
2875         }
2876         return 0;
2877 }
2878
2879 int btrfs_previous_item(struct btrfs_root *root,
2880                         struct btrfs_path *path, u64 min_objectid,
2881                         int type)
2882 {
2883         struct btrfs_key found_key;
2884         struct extent_buffer *leaf;
2885         u32 nritems;
2886         int ret;
2887
2888         while(1) {
2889                 if (path->slots[0] == 0) {
2890                         ret = btrfs_prev_leaf(root, path);
2891                         if (ret != 0)
2892                                 return ret;
2893                 } else {
2894                         path->slots[0]--;
2895                 }
2896                 leaf = path->nodes[0];
2897                 nritems = btrfs_header_nritems(leaf);
2898                 if (nritems == 0)
2899                         return 1;
2900                 if (path->slots[0] == nritems)
2901                         path->slots[0]--;
2902
2903                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2904                 if (found_key.objectid < min_objectid)
2905                         break;
2906                 if (found_key.type == type)
2907                         return 0;
2908                 if (found_key.objectid == min_objectid &&
2909                     found_key.type < type)
2910                         break;
2911         }
2912         return 1;
2913 }
2914
2915 /*
2916  * search in extent tree to find a previous Metadata/Data extent item with
2917  * min objecitd.
2918  *
2919  * returns 0 if something is found, 1 if nothing was found and < 0 on error
2920  */
2921 int btrfs_previous_extent_item(struct btrfs_root *root,
2922                         struct btrfs_path *path, u64 min_objectid)
2923 {
2924         struct btrfs_key found_key;
2925         struct extent_buffer *leaf;
2926         u32 nritems;
2927         int ret;
2928
2929         while (1) {
2930                 if (path->slots[0] == 0) {
2931                         ret = btrfs_prev_leaf(root, path);
2932                         if (ret != 0)
2933                                 return ret;
2934                 } else {
2935                         path->slots[0]--;
2936                 }
2937                 leaf = path->nodes[0];
2938                 nritems = btrfs_header_nritems(leaf);
2939                 if (nritems == 0)
2940                         return 1;
2941                 if (path->slots[0] == nritems)
2942                         path->slots[0]--;
2943
2944                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2945                 if (found_key.objectid < min_objectid)
2946                         break;
2947                 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
2948                     found_key.type == BTRFS_METADATA_ITEM_KEY)
2949                         return 0;
2950                 if (found_key.objectid == min_objectid &&
2951                     found_key.type < BTRFS_EXTENT_ITEM_KEY)
2952                         break;
2953         }
2954         return 1;
2955 }
2956
2957 /*
2958  * Search in extent tree to found next meta/data extent
2959  * Caller needs to check for no-hole or skinny metadata features.
2960  */
2961 int btrfs_next_extent_item(struct btrfs_root *root,
2962                         struct btrfs_path *path, u64 max_objectid)
2963 {
2964         struct btrfs_key found_key;
2965         int ret;
2966
2967         while (1) {
2968                 ret = btrfs_next_item(root, path);
2969                 if (ret)
2970                         return ret;
2971                 btrfs_item_key_to_cpu(path->nodes[0], &found_key,
2972                                       path->slots[0]);
2973                 if (found_key.objectid > max_objectid)
2974                         return 1;
2975                 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
2976                     found_key.type == BTRFS_METADATA_ITEM_KEY)
2977                 return 0;
2978         }
2979 }