fs/btrfs/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
  19 #include <linux/highmem.h>
  20 #include "ctree.h"
  21 #include "disk-io.h"
  22 #include "transaction.h"
  23 #include "print-tree.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);
  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);
  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 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  38                    struct btrfs_path *path, int level, int slot);
  39
  40 inline void btrfs_init_path(struct btrfs_path *p)
  41 {
  42         memset(p, 0, sizeof(*p));
  43 }
  44
  45 struct btrfs_path *btrfs_alloc_path(void)
  46 {
  47         struct btrfs_path *path;
  48         path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
  49         if (path) {
  50                 btrfs_init_path(path);
  51                 path->reada = 1;
  52         }
  53         return path;
  54 }
  55
  56 void btrfs_free_path(struct btrfs_path *p)
  57 {
  58         btrfs_release_path(NULL, p);
  59         kmem_cache_free(btrfs_path_cachep, p);
  60 }
  61
  62 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
  63 {
  64         int i;
  65         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  66                 if (!p->nodes[i])
  67                         break;
  68                 free_extent_buffer(p->nodes[i]);
  69         }
  70         memset(p, 0, sizeof(*p));
  71 }
  72
  73 static int __btrfs_cow_block(struct btrfs_trans_handle *trans,
  74                              struct btrfs_root *root,
  75                              struct extent_buffer *buf,
  76                              struct extent_buffer *parent, int parent_slot,
  77                              struct extent_buffer **cow_ret,
  78                              u64 search_start, u64 empty_size)
  79 {
  80         struct extent_buffer *cow;
  81         int ret = 0;
  82         int different_trans = 0;
  83
  84         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
  85
  86         cow = btrfs_alloc_free_block(trans, root, search_start, empty_size);
  87         if (IS_ERR(cow))
  88                 return PTR_ERR(cow);
  89
  90         if (buf->len != root->sectorsize || cow->len != root->sectorsize)
  91                 WARN_ON(1);
  92
  93         copy_extent_buffer(cow, buf, 0, 0, cow->len);
  94         btrfs_set_header_blocknr(cow, extent_buffer_blocknr(cow));
  95         btrfs_set_header_generation(cow, trans->transid);
  96         btrfs_set_header_owner(cow, root->root_key.objectid);
  97
  98         WARN_ON(btrfs_header_generation(buf) > trans->transid);
  99         if (btrfs_header_generation(buf) != trans->transid) {
 100                 different_trans = 1;
 101                 ret = btrfs_inc_ref(trans, root, buf);
 102                 if (ret)
 103                         return ret;
 104         } else {
 105                 clean_tree_block(trans, root, buf);
 106         }
 107
 108         if (buf == root->node) {
 109                 root->node = cow;
 110                 extent_buffer_get(cow);
 111                 if (buf != root->commit_root) {
 112                         btrfs_free_extent(trans, root,
 113                                           extent_buffer_blocknr(buf), 1, 1);
 114                 }
 115                 free_extent_buffer(buf);
 116         } else {
 117                 btrfs_set_node_blockptr(parent, parent_slot,
 118                                         extent_buffer_blocknr(cow));
 119                 btrfs_mark_buffer_dirty(parent);
 120                 WARN_ON(btrfs_header_generation(parent) != trans->transid);
 121                 btrfs_free_extent(trans, root, extent_buffer_blocknr(buf),1,1);
 122         }
 123         free_extent_buffer(buf);
 124         btrfs_mark_buffer_dirty(cow);
 125         *cow_ret = cow;
 126         return 0;
 127 }
 128
 129 int btrfs_cow_block(struct btrfs_trans_handle *trans,
 130                     struct btrfs_root *root, struct extent_buffer *buf,
 131                     struct extent_buffer *parent, int parent_slot,
 132                     struct extent_buffer **cow_ret)
 133 {
 134         u64 search_start;
 135         if (trans->transaction != root->fs_info->running_transaction) {
 136                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 137                        root->fs_info->running_transaction->transid);
 138                 WARN_ON(1);
 139         }
 140         if (trans->transid != root->fs_info->generation) {
 141                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 142                        root->fs_info->generation);
 143                 WARN_ON(1);
 144         }
 145         if (btrfs_header_generation(buf) == trans->transid) {
 146                 *cow_ret = buf;
 147                 return 0;
 148         }
 149
 150         search_start = extent_buffer_blocknr(buf) & ~((u64)65535);
 151         return __btrfs_cow_block(trans, root, buf, parent,
 152                                  parent_slot, cow_ret, search_start, 0);
 153 }
 154
 155 static int close_blocks(u64 blocknr, u64 other)
 156 {
 157         if (blocknr < other && other - blocknr < 8)
 158                 return 1;
 159         if (blocknr > other && blocknr - other < 8)
 160                 return 1;
 161         return 0;
 162 }
 163
 164 #if 0
 165 static int should_defrag_leaf(struct extent_buffer *eb)
 166 {
 167         return 0;
 168         struct btrfs_leaf *leaf = btrfs_buffer_leaf(eb);
 169         struct btrfs_disk_key *key;
 170         u32 nritems;
 171
 172         if (buffer_defrag(bh))
 173                 return 1;
 174
 175         nritems = btrfs_header_nritems(&leaf->header);
 176         if (nritems == 0)
 177                 return 0;
 178
 179         key = &leaf->items[0].key;
 180         if (btrfs_disk_key_type(key) == BTRFS_DIR_ITEM_KEY)
 181                 return 1;
 182
 183         key = &leaf->items[nritems-1].key;
 184         if (btrfs_disk_key_type(key) == BTRFS_DIR_ITEM_KEY)
 185                 return 1;
 186         if (nritems > 4) {
 187                 key = &leaf->items[nritems/2].key;
 188                 if (btrfs_disk_key_type(key) == BTRFS_DIR_ITEM_KEY)
 189                         return 1;
 190         }
 191         return 0;
 192 }
 193 #endif
 194
 195 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 196                        struct btrfs_root *root, struct extent_buffer *parent,
 197                        int cache_only, u64 *last_ret)
 198 {
 199         return 0;
 200 #if 0
 201         struct btrfs_node *parent_node;
 202         struct extent_buffer *cur_eb;
 203         struct extent_buffer *tmp_eb;
 204         u64 blocknr;
 205         u64 search_start = *last_ret;
 206         u64 last_block = 0;
 207         u64 other;
 208         u32 parent_nritems;
 209         int start_slot;
 210         int end_slot;
 211         int i;
 212         int err = 0;
 213         int parent_level;
 214
 215         if (trans->transaction != root->fs_info->running_transaction) {
 216                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 217                        root->fs_info->running_transaction->transid);
 218                 WARN_ON(1);
 219         }
 220         if (trans->transid != root->fs_info->generation) {
 221                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 222                        root->fs_info->generation);
 223                 WARN_ON(1);
 224         }
 225         if (buffer_defrag_done(parent))
 226                 return 0;
 227
 228         parent_node = btrfs_buffer_node(parent);
 229         parent_nritems = btrfs_header_nritems(&parent_node->header);
 230         parent_level = btrfs_header_level(&parent_node->header);
 231
 232         start_slot = 0;
 233         end_slot = parent_nritems;
 234
 235         if (parent_nritems == 1)
 236                 return 0;
 237
 238         for (i = start_slot; i < end_slot; i++) {
 239                 int close = 1;
 240                 blocknr = btrfs_node_blockptr(parent_node, i);
 241                 if (last_block == 0)
 242                         last_block = blocknr;
 243                 if (i > 0) {
 244                         other = btrfs_node_blockptr(parent_node, i - 1);
 245                         close = close_blocks(blocknr, other);
 246                 }
 247                 if (close && i < end_slot - 1) {
 248                         other = btrfs_node_blockptr(parent_node, i + 1);
 249                         close = close_blocks(blocknr, other);
 250                 }
 251                 if (close) {
 252                         last_block = blocknr;
 253                         continue;
 254                 }
 255
 256                 cur_bh = btrfs_find_tree_block(root, blocknr);
 257                 if (!cur_bh || !buffer_uptodate(cur_bh) ||
 258                     buffer_locked(cur_bh) ||
 259                     (parent_level != 1 && !buffer_defrag(cur_bh)) ||
 260                     (parent_level == 1 && !should_defrag_leaf(cur_bh))) {
 261                         if (cache_only) {
 262                                 brelse(cur_bh);
 263                                 continue;
 264                         }
 265                         if (!cur_bh || !buffer_uptodate(cur_bh) ||
 266                             buffer_locked(cur_bh)) {
 267                                 brelse(cur_bh);
 268                                 cur_bh = read_tree_block(root, blocknr);
 269                         }
 270                 }
 271                 if (search_start == 0)
 272                         search_start = last_block & ~((u64)65535);
 273
 274                 err = __btrfs_cow_block(trans, root, cur_bh, parent, i,
 275                                         &tmp_bh, search_start,
 276                                         min(8, end_slot - i));
 277                 if (err) {
 278                         brelse(cur_bh);
 279                         break;
 280                 }
 281                 search_start = bh_blocknr(tmp_bh);
 282                 *last_ret = search_start;
 283                 if (parent_level == 1)
 284                         clear_buffer_defrag(tmp_bh);
 285                 set_buffer_defrag_done(tmp_bh);
 286                 brelse(tmp_bh);
 287         }
 288         return err;
 289 #endif
 290 }
 291
 292 /*
 293  * The leaf data grows from end-to-front in the node.
 294  * this returns the address of the start of the last item,
 295  * which is the stop of the leaf data stack
 296  */
 297 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 298                                          struct extent_buffer *leaf)
 299 {
 300         u32 nr = btrfs_header_nritems(leaf);
 301         if (nr == 0)
 302                 return BTRFS_LEAF_DATA_SIZE(root);
 303         return btrfs_item_offset_nr(leaf, nr - 1);
 304 }
 305
 306 /*
 307  * compare two keys in a memcmp fashion
 308  */
 309 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 310 {
 311         struct btrfs_key k1;
 312
 313         btrfs_disk_key_to_cpu(&k1, disk);
 314
 315         if (k1.objectid > k2->objectid)
 316                 return 1;
 317         if (k1.objectid < k2->objectid)
 318                 return -1;
 319         if (k1.type > k2->type)
 320                 return 1;
 321         if (k1.type < k2->type)
 322                 return -1;
 323         if (k1.offset > k2->offset)
 324                 return 1;
 325         if (k1.offset < k2->offset)
 326                 return -1;
 327         return 0;
 328 }
 329
 330 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 331                       int level)
 332 {
 333         struct extent_buffer *parent = NULL;
 334         struct extent_buffer *node = path->nodes[level];
 335         struct btrfs_disk_key parent_key;
 336         struct btrfs_disk_key node_key;
 337         int parent_slot;
 338         int slot;
 339         struct btrfs_key cpukey;
 340         u32 nritems = btrfs_header_nritems(node);
 341
 342         if (path->nodes[level + 1])
 343                 parent = path->nodes[level + 1];
 344
 345         slot = path->slots[level];
 346         BUG_ON(nritems == 0);
 347         if (parent) {
 348                 parent_slot = path->slots[level + 1];
 349                 btrfs_node_key(parent, &parent_key, parent_slot);
 350                 btrfs_node_key(node, &node_key, 0);
 351                 BUG_ON(memcmp(&parent_key, &node_key,
 352                               sizeof(struct btrfs_disk_key)));
 353                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 354                        btrfs_header_blocknr(node));
 355         }
 356         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 357         if (slot != 0) {
 358                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 359                 btrfs_node_key(node, &node_key, slot);
 360                 BUG_ON(comp_keys(&node_key, &cpukey) <= 0);
 361         }
 362         if (slot < nritems - 1) {
 363                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 364                 btrfs_node_key(node, &node_key, slot);
 365                 BUG_ON(comp_keys(&node_key, &cpukey) >= 0);
 366         }
 367         return 0;
 368 }
 369
 370 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 371                       int level)
 372 {
 373         struct extent_buffer *leaf = path->nodes[level];
 374         struct extent_buffer *parent = NULL;
 375         int parent_slot;
 376         struct btrfs_key cpukey;
 377         struct btrfs_disk_key parent_key;
 378         struct btrfs_disk_key leaf_key;
 379         int slot = path->slots[0];
 380
 381         u32 nritems = btrfs_header_nritems(leaf);
 382
 383         if (path->nodes[level + 1])
 384                 parent = path->nodes[level + 1];
 385
 386         if (nritems == 0)
 387                 return 0;
 388
 389         if (parent) {
 390                 parent_slot = path->slots[level + 1];
 391                 btrfs_node_key(parent, &parent_key, parent_slot);
 392                 btrfs_item_key(leaf, &leaf_key, 0);
 393
 394                 BUG_ON(memcmp(&parent_key, &leaf_key,
 395                        sizeof(struct btrfs_disk_key)));
 396                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 397                        btrfs_header_blocknr(leaf));
 398         }
 399 #if 0
 400         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 401                 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
 402                 btrfs_item_key(leaf, &leaf_key, i);
 403                 if (comp_keys(&leaf_key, &cpukey) >= 0) {
 404                         btrfs_print_leaf(root, leaf);
 405                         printk("slot %d offset bad key\n", i);
 406                         BUG_ON(1);
 407                 }
 408                 if (btrfs_item_offset_nr(leaf, i) !=
 409                         btrfs_item_end_nr(leaf, i + 1)) {
 410                         btrfs_print_leaf(root, leaf);
 411                         printk("slot %d offset bad\n", i);
 412                         BUG_ON(1);
 413                 }
 414                 if (i == 0) {
 415                         if (btrfs_item_offset_nr(leaf, i) +
 416                                btrfs_item_size_nr(leaf, i) !=
 417                                BTRFS_LEAF_DATA_SIZE(root)) {
 418                                 btrfs_print_leaf(root, leaf);
 419                                 printk("slot %d first offset bad\n", i);
 420                                 BUG_ON(1);
 421                         }
 422                 }
 423         }
 424         if (nritems > 0) {
 425                 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
 426                                 btrfs_print_leaf(root, leaf);
 427                                 printk("slot %d bad size \n", nritems - 1);
 428                                 BUG_ON(1);
 429                 }
 430         }
 431 #endif
 432         if (slot != 0 && slot < nritems - 1) {
 433                 btrfs_item_key(leaf, &leaf_key, slot);
 434                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 435                 if (comp_keys(&leaf_key, &cpukey) <= 0) {
 436                         btrfs_print_leaf(root, leaf);
 437                         printk("slot %d offset bad key\n", slot);
 438                         BUG_ON(1);
 439                 }
 440                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 441                        btrfs_item_end_nr(leaf, slot)) {
 442                         btrfs_print_leaf(root, leaf);
 443                         printk("slot %d offset bad\n", slot);
 444                         BUG_ON(1);
 445                 }
 446         }
 447         if (slot < nritems - 1) {
 448                 btrfs_item_key(leaf, &leaf_key, slot);
 449                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 450                 BUG_ON(comp_keys(&leaf_key, &cpukey) >= 0);
 451                 if (btrfs_item_offset_nr(leaf, slot) !=
 452                         btrfs_item_end_nr(leaf, slot + 1)) {
 453                         btrfs_print_leaf(root, leaf);
 454                         printk("slot %d offset bad\n", slot);
 455                         BUG_ON(1);
 456                 }
 457         }
 458         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 459                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 460         return 0;
 461 }
 462
 463 static int check_block(struct btrfs_root *root, struct btrfs_path *path,
 464                         int level)
 465 {
 466         struct extent_buffer *buf = path->nodes[level];
 467         char fsid[BTRFS_FSID_SIZE];
 468
 469         read_extent_buffer(buf, fsid, (unsigned long)btrfs_header_fsid(buf),
 470                            BTRFS_FSID_SIZE);
 471
 472         if (memcmp(fsid, root->fs_info->fsid, BTRFS_FSID_SIZE)) {
 473                 int i = 0;
 474                 printk("warning bad block %Lu\n", buf->start);
 475                 if (!btrfs_buffer_uptodate(buf)) {
 476                         WARN_ON(1);
 477                 }
 478                 for (i = 0; i < BTRFS_FSID_SIZE; i++) {
 479                         printk("%x:%x ", root->fs_info->fsid[i], fsid[i]);
 480                 }
 481                 printk("\n");
 482                 // BUG();
 483         }
 484         if (level == 0)
 485                 return check_leaf(root, path, level);
 486         return check_node(root, path, level);
 487 }
 488
 489 /*
 490  * search for key in the extent_buffer.  The items start at offset p,
 491  * and they are item_size apart.  There are 'max' items in p.
 492  *
 493  * the slot in the array is returned via slot, and it points to
 494  * the place where you would insert key if it is not found in
 495  * the array.
 496  *
 497  * slot may point to max if the key is bigger than all of the keys
 498  */
 499 static int generic_bin_search(struct extent_buffer *eb, unsigned long p,
 500                               int item_size, struct btrfs_key *key,
 501                               int max, int *slot)
 502 {
 503         int low = 0;
 504         int high = max;
 505         int mid;
 506         int ret;
 507         struct btrfs_disk_key *tmp;
 508         struct btrfs_disk_key unaligned;
 509         unsigned long offset;
 510         char *map_token = NULL;
 511         char *kaddr = NULL;
 512         unsigned long map_start = 0;
 513         unsigned long map_len = 0;
 514
 515         while(low < high) {
 516                 mid = (low + high) / 2;
 517                 offset = p + mid * item_size;
 518
 519                 if (!map_token || offset < map_start ||
 520                     (offset + sizeof(struct btrfs_disk_key)) >
 521                     map_start + map_len) {
 522                         if (map_token)
 523                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 524                         map_extent_buffer(eb, offset, &map_token, &kaddr,
 525                                           &map_start, &map_len, KM_USER0);
 526
 527                 }
 528                 if (offset + sizeof(struct btrfs_disk_key) >
 529                     map_start + map_len) {
 530                         unmap_extent_buffer(eb, map_token, KM_USER0);
 531                         read_extent_buffer(eb, &unaligned,
 532                                            offset, sizeof(unaligned));
 533                         map_token = NULL;
 534                         tmp = &unaligned;
 535                 } else {
 536                         tmp = (struct btrfs_disk_key *)(kaddr + offset -
 537                                                         map_start);
 538                 }
 539                 ret = comp_keys(tmp, key);
 540
 541                 if (ret < 0)
 542                         low = mid + 1;
 543                 else if (ret > 0)
 544                         high = mid;
 545                 else {
 546                         *slot = mid;
 547                         unmap_extent_buffer(eb, map_token, KM_USER0);
 548                         return 0;
 549                 }
 550         }
 551         *slot = low;
 552         if (map_token)
 553                 unmap_extent_buffer(eb, map_token, KM_USER0);
 554         return 1;
 555 }
 556
 557 /*
 558  * simple bin_search frontend that does the right thing for
 559  * leaves vs nodes
 560  */
 561 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 562                       int level, int *slot)
 563 {
 564         if (level == 0) {
 565                 return generic_bin_search(eb,
 566                                           offsetof(struct btrfs_leaf, items),
 567                                           sizeof(struct btrfs_item),
 568                                           key, btrfs_header_nritems(eb),
 569                                           slot);
 570         } else {
 571                 return generic_bin_search(eb,
 572                                           offsetof(struct btrfs_node, ptrs),
 573                                           sizeof(struct btrfs_key_ptr),
 574                                           key, btrfs_header_nritems(eb),
 575                                           slot);
 576         }
 577         return -1;
 578 }
 579
 580 static struct extent_buffer *read_node_slot(struct btrfs_root *root,
 581                                    struct extent_buffer *parent, int slot)
 582 {
 583         if (slot < 0)
 584                 return NULL;
 585         if (slot >= btrfs_header_nritems(parent))
 586                 return NULL;
 587         return read_tree_block(root, btrfs_node_blockptr(parent, slot));
 588 }
 589
 590 static int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root
 591                          *root, struct btrfs_path *path, int level)
 592 {
 593         struct extent_buffer *right = NULL;
 594         struct extent_buffer *mid;
 595         struct extent_buffer *left = NULL;
 596         struct extent_buffer *parent = NULL;
 597         int ret = 0;
 598         int wret;
 599         int pslot;
 600         int orig_slot = path->slots[level];
 601         int err_on_enospc = 0;
 602         u64 orig_ptr;
 603
 604         if (level == 0)
 605                 return 0;
 606
 607         mid = path->nodes[level];
 608         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 609
 610         if (level < BTRFS_MAX_LEVEL - 1)
 611                 parent = path->nodes[level + 1];
 612         pslot = path->slots[level + 1];
 613
 614         /*
 615          * deal with the case where there is only one pointer in the root
 616          * by promoting the node below to a root
 617          */
 618         if (!parent) {
 619                 struct extent_buffer *child;
 620                 u64 blocknr = extent_buffer_blocknr(mid);
 621
 622                 if (btrfs_header_nritems(mid) != 1)
 623                         return 0;
 624
 625                 /* promote the child to a root */
 626                 child = read_node_slot(root, mid, 0);
 627                 BUG_ON(!child);
 628                 root->node = child;
 629                 path->nodes[level] = NULL;
 630                 clean_tree_block(trans, root, mid);
 631                 wait_on_tree_block_writeback(root, mid);
 632                 /* once for the path */
 633                 free_extent_buffer(mid);
 634                 /* once for the root ptr */
 635                 free_extent_buffer(mid);
 636                 return btrfs_free_extent(trans, root, blocknr, 1, 1);
 637         }
 638         if (btrfs_header_nritems(mid) >
 639             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 640                 return 0;
 641
 642         if (btrfs_header_nritems(mid) < 2)
 643                 err_on_enospc = 1;
 644
 645         left = read_node_slot(root, parent, pslot - 1);
 646         if (left) {
 647                 wret = btrfs_cow_block(trans, root, left,
 648                                        parent, pslot - 1, &left);
 649                 if (wret) {
 650                         ret = wret;
 651                         goto enospc;
 652                 }
 653         }
 654         right = read_node_slot(root, parent, pslot + 1);
 655         if (right) {
 656                 wret = btrfs_cow_block(trans, root, right,
 657                                        parent, pslot + 1, &right);
 658                 if (wret) {
 659                         ret = wret;
 660                         goto enospc;
 661                 }
 662         }
 663
 664         /* first, try to make some room in the middle buffer */
 665         if (left) {
 666                 orig_slot += btrfs_header_nritems(left);
 667                 wret = push_node_left(trans, root, left, mid);
 668                 if (wret < 0)
 669                         ret = wret;
 670                 if (btrfs_header_nritems(mid) < 2)
 671                         err_on_enospc = 1;
 672         }
 673
 674         /*
 675          * then try to empty the right most buffer into the middle
 676          */
 677         if (right) {
 678                 wret = push_node_left(trans, root, mid, right);
 679                 if (wret < 0 && wret != -ENOSPC)
 680                         ret = wret;
 681                 if (btrfs_header_nritems(right) == 0) {
 682                         u64 blocknr = extent_buffer_blocknr(right);
 683                         clean_tree_block(trans, root, right);
 684                         wait_on_tree_block_writeback(root, right);
 685                         free_extent_buffer(right);
 686                         right = NULL;
 687                         wret = del_ptr(trans, root, path, level + 1, pslot +
 688                                        1);
 689                         if (wret)
 690                                 ret = wret;
 691                         wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
 692                         if (wret)
 693                                 ret = wret;
 694                 } else {
 695                         struct btrfs_disk_key right_key;
 696                         btrfs_node_key(right, &right_key, 0);
 697                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 698                         btrfs_mark_buffer_dirty(parent);
 699                 }
 700         }
 701         if (btrfs_header_nritems(mid) == 1) {
 702                 /*
 703                  * we're not allowed to leave a node with one item in the
 704                  * tree during a delete.  A deletion from lower in the tree
 705                  * could try to delete the only pointer in this node.
 706                  * So, pull some keys from the left.
 707                  * There has to be a left pointer at this point because
 708                  * otherwise we would have pulled some pointers from the
 709                  * right
 710                  */
 711                 BUG_ON(!left);
 712                 wret = balance_node_right(trans, root, mid, left);
 713                 if (wret < 0) {
 714                         ret = wret;
 715                         goto enospc;
 716                 }
 717                 BUG_ON(wret == 1);
 718         }
 719         if (btrfs_header_nritems(mid) == 0) {
 720                 /* we've managed to empty the middle node, drop it */
 721                 u64 blocknr = extent_buffer_blocknr(mid);
 722                 clean_tree_block(trans, root, mid);
 723                 wait_on_tree_block_writeback(root, mid);
 724                 free_extent_buffer(mid);
 725                 mid = NULL;
 726                 wret = del_ptr(trans, root, path, level + 1, pslot);
 727                 if (wret)
 728                         ret = wret;
 729                 wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
 730                 if (wret)
 731                         ret = wret;
 732         } else {
 733                 /* update the parent key to reflect our changes */
 734                 struct btrfs_disk_key mid_key;
 735                 btrfs_node_key(mid, &mid_key, 0);
 736                 btrfs_set_node_key(parent, &mid_key, pslot);
 737                 btrfs_mark_buffer_dirty(parent);
 738         }
 739
 740         /* update the path */
 741         if (left) {
 742                 if (btrfs_header_nritems(left) > orig_slot) {
 743                         extent_buffer_get(left);
 744                         path->nodes[level] = left;
 745                         path->slots[level + 1] -= 1;
 746                         path->slots[level] = orig_slot;
 747                         if (mid)
 748                                 free_extent_buffer(mid);
 749                 } else {
 750                         orig_slot -= btrfs_header_nritems(left);
 751                         path->slots[level] = orig_slot;
 752                 }
 753         }
 754         /* double check we haven't messed things up */
 755         check_block(root, path, level);
 756         if (orig_ptr !=
 757             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 758                 BUG();
 759 enospc:
 760         if (right)
 761                 free_extent_buffer(right);
 762         if (left)
 763                 free_extent_buffer(left);
 764         return ret;
 765 }
 766
 767 /* returns zero if the push worked, non-zero otherwise */
 768 static int push_nodes_for_insert(struct btrfs_trans_handle *trans,
 769                                 struct btrfs_root *root,
 770                                 struct btrfs_path *path, int level)
 771 {
 772         struct extent_buffer *right = NULL;
 773         struct extent_buffer *mid;
 774         struct extent_buffer *left = NULL;
 775         struct extent_buffer *parent = NULL;
 776         int ret = 0;
 777         int wret;
 778         int pslot;
 779         int orig_slot = path->slots[level];
 780         u64 orig_ptr;
 781
 782         if (level == 0)
 783                 return 1;
 784
 785         mid = path->nodes[level];
 786         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 787
 788         if (level < BTRFS_MAX_LEVEL - 1)
 789                 parent = path->nodes[level + 1];
 790         pslot = path->slots[level + 1];
 791
 792         if (!parent)
 793                 return 1;
 794
 795         left = read_node_slot(root, parent, pslot - 1);
 796
 797         /* first, try to make some room in the middle buffer */
 798         if (left) {
 799                 u32 left_nr;
 800                 left_nr = btrfs_header_nritems(left);
 801                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 802                         wret = 1;
 803                 } else {
 804                         ret = btrfs_cow_block(trans, root, left, parent,
 805                                               pslot - 1, &left);
 806                         if (ret)
 807                                 wret = 1;
 808                         else {
 809                                 wret = push_node_left(trans, root,
 810                                                       left, mid);
 811                         }
 812                 }
 813                 if (wret < 0)
 814                         ret = wret;
 815                 if (wret == 0) {
 816                         struct btrfs_disk_key disk_key;
 817                         orig_slot += left_nr;
 818                         btrfs_node_key(mid, &disk_key, 0);
 819                         btrfs_set_node_key(parent, &disk_key, pslot);
 820                         btrfs_mark_buffer_dirty(parent);
 821                         if (btrfs_header_nritems(left) > orig_slot) {
 822                                 path->nodes[level] = left;
 823                                 path->slots[level + 1] -= 1;
 824                                 path->slots[level] = orig_slot;
 825                                 free_extent_buffer(mid);
 826                         } else {
 827                                 orig_slot -=
 828                                         btrfs_header_nritems(left);
 829                                 path->slots[level] = orig_slot;
 830                                 free_extent_buffer(left);
 831                         }
 832                         check_node(root, path, level);
 833                         return 0;
 834                 }
 835                 free_extent_buffer(left);
 836         }
 837         right= read_node_slot(root, parent, pslot + 1);
 838
 839         /*
 840          * then try to empty the right most buffer into the middle
 841          */
 842         if (right) {
 843                 u32 right_nr;
 844                 right_nr = btrfs_header_nritems(right);
 845                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 846                         wret = 1;
 847                 } else {
 848                         ret = btrfs_cow_block(trans, root, right,
 849                                               parent, pslot + 1,
 850                                               &right);
 851                         if (ret)
 852                                 wret = 1;
 853                         else {
 854                                 wret = balance_node_right(trans, root,
 855                                                           right, mid);
 856                         }
 857                 }
 858                 if (wret < 0)
 859                         ret = wret;
 860                 if (wret == 0) {
 861                         struct btrfs_disk_key disk_key;
 862
 863                         btrfs_node_key(right, &disk_key, 0);
 864                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
 865                         btrfs_mark_buffer_dirty(parent);
 866
 867                         if (btrfs_header_nritems(mid) <= orig_slot) {
 868                                 path->nodes[level] = right;
 869                                 path->slots[level + 1] += 1;
 870                                 path->slots[level] = orig_slot -
 871                                         btrfs_header_nritems(mid);
 872                                 free_extent_buffer(mid);
 873                         } else {
 874                                 free_extent_buffer(right);
 875                         }
 876                         check_node(root, path, level);
 877                         return 0;
 878                 }
 879                 free_extent_buffer(right);
 880         }
 881         check_node(root, path, level);
 882         return 1;
 883 }
 884
 885 /*
 886  * readahead one full node of leaves
 887  */
 888 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 889                              int level, int slot)
 890 {
 891         struct extent_buffer *node;
 892         int i;
 893         u32 nritems;
 894         u64 blocknr;
 895         u64 search;
 896         u64 cluster_start;
 897         int ret;
 898         int nread = 0;
 899         int direction = path->reada;
 900         struct radix_tree_root found;
 901         unsigned long gang[8];
 902         struct extent_buffer *eb;
 903
 904         if (level == 0)
 905                 return;
 906
 907         if (!path->nodes[level])
 908                 return;
 909
 910         node = path->nodes[level];
 911         search = btrfs_node_blockptr(node, slot);
 912         eb = btrfs_find_tree_block(root, search);
 913         if (eb) {
 914                 free_extent_buffer(eb);
 915                 return;
 916         }
 917
 918         init_bit_radix(&found);
 919         nritems = btrfs_header_nritems(node);
 920         for (i = slot; i < nritems; i++) {
 921                 blocknr = btrfs_node_blockptr(node, i);
 922                 set_radix_bit(&found, blocknr);
 923         }
 924         if (direction > 0) {
 925                 cluster_start = search - 4;
 926                 if (cluster_start > search)
 927                         cluster_start = 0;
 928         } else
 929                 cluster_start = search + 4;
 930         while(1) {
 931                 ret = find_first_radix_bit(&found, gang, 0, ARRAY_SIZE(gang));
 932                 if (!ret)
 933                         break;
 934                 for (i = 0; i < ret; i++) {
 935                         blocknr = gang[i];
 936                         clear_radix_bit(&found, blocknr);
 937                         if (path->reada == 1 && nread > 16)
 938                                 continue;
 939                         if (close_blocks(cluster_start, blocknr)) {
 940                                 readahead_tree_block(root, blocknr);
 941                                 nread++;
 942                                 cluster_start = blocknr;
 943                         }
 944                 }
 945         }
 946 }
 947 /*
 948  * look for key in the tree.  path is filled in with nodes along the way
 949  * if key is found, we return zero and you can find the item in the leaf
 950  * level of the path (level 0)
 951  *
 952  * If the key isn't found, the path points to the slot where it should
 953  * be inserted, and 1 is returned.  If there are other errors during the
 954  * search a negative error number is returned.
 955  *
 956  * if ins_len > 0, nodes and leaves will be split as we walk down the
 957  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
 958  * possible)
 959  */
 960 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 961                       *root, struct btrfs_key *key, struct btrfs_path *p, int
 962                       ins_len, int cow)
 963 {
 964         struct extent_buffer *b;
 965         u64 blocknr;
 966         int slot;
 967         int ret;
 968         int level;
 969         int should_reada = p->reada;
 970         u8 lowest_level = 0;
 971
 972         lowest_level = p->lowest_level;
 973         WARN_ON(lowest_level && ins_len);
 974         WARN_ON(p->nodes[0] != NULL);
 975         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
 976 again:
 977         b = root->node;
 978         extent_buffer_get(b);
 979         while (b) {
 980                 level = btrfs_header_level(b);
 981                 if (cow) {
 982                         int wret;
 983                         wret = btrfs_cow_block(trans, root, b,
 984                                                p->nodes[level + 1],
 985                                                p->slots[level + 1],
 986                                                &b);
 987                         if (wret) {
 988                                 free_extent_buffer(b);
 989                                 return wret;
 990                         }
 991                 }
 992                 BUG_ON(!cow && ins_len);
 993                 if (level != btrfs_header_level(b))
 994                         WARN_ON(1);
 995                 level = btrfs_header_level(b);
 996                 p->nodes[level] = b;
 997                 ret = check_block(root, p, level);
 998                 if (ret)
 999                         return -1;
1000                 ret = bin_search(b, key, level, &slot);
1001                 if (level != 0) {
1002                         if (ret && slot > 0)
1003                                 slot -= 1;
1004                         p->slots[level] = slot;
1005                         if (ins_len > 0 && btrfs_header_nritems(b) >=
1006                             BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1007                                 int sret = split_node(trans, root, p, level);
1008                                 BUG_ON(sret > 0);
1009                                 if (sret)
1010                                         return sret;
1011                                 b = p->nodes[level];
1012                                 slot = p->slots[level];
1013                         } else if (ins_len < 0) {
1014                                 int sret = balance_level(trans, root, p,
1015                                                          level);
1016                                 if (sret)
1017                                         return sret;
1018                                 b = p->nodes[level];
1019                                 if (!b)
1020                                         goto again;
1021                                 slot = p->slots[level];
1022                                 BUG_ON(btrfs_header_nritems(b) == 1);
1023                         }
1024                         /* this is only true while dropping a snapshot */
1025                         if (level == lowest_level)
1026                                 break;
1027                         blocknr = btrfs_node_blockptr(b, slot);
1028                         if (should_reada)
1029                                 reada_for_search(root, p, level, slot);
1030                         b = read_tree_block(root, btrfs_node_blockptr(b, slot));
1031                 } else {
1032                         p->slots[level] = slot;
1033                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1034                             sizeof(struct btrfs_item) + ins_len) {
1035                                 int sret = split_leaf(trans, root, key,
1036                                                       p, ins_len);
1037                                 BUG_ON(sret > 0);
1038                                 if (sret)
1039                                         return sret;
1040                         }
1041                         return ret;
1042                 }
1043         }
1044         return 1;
1045 }
1046
1047 /*
1048  * adjust the pointers going up the tree, starting at level
1049  * making sure the right key of each node is points to 'key'.
1050  * This is used after shifting pointers to the left, so it stops
1051  * fixing up pointers when a given leaf/node is not in slot 0 of the
1052  * higher levels
1053  *
1054  * If this fails to write a tree block, it returns -1, but continues
1055  * fixing up the blocks in ram so the tree is consistent.
1056  */
1057 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1058                           struct btrfs_root *root, struct btrfs_path *path,
1059                           struct btrfs_disk_key *key, int level)
1060 {
1061         int i;
1062         int ret = 0;
1063         struct extent_buffer *t;
1064
1065         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1066                 int tslot = path->slots[i];
1067                 if (!path->nodes[i])
1068                         break;
1069                 t = path->nodes[i];
1070                 btrfs_set_node_key(t, key, tslot);
1071                 btrfs_mark_buffer_dirty(path->nodes[i]);
1072                 if (tslot != 0)
1073                         break;
1074         }
1075         return ret;
1076 }
1077
1078 /*
1079  * try to push data from one node into the next node left in the
1080  * tree.
1081  *
1082  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1083  * error, and > 0 if there was no room in the left hand block.
1084  */
1085 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
1086                           *root, struct extent_buffer *dst,
1087                           struct extent_buffer *src)
1088 {
1089         int push_items = 0;
1090         int src_nritems;
1091         int dst_nritems;
1092         int ret = 0;
1093
1094         src_nritems = btrfs_header_nritems(src);
1095         dst_nritems = btrfs_header_nritems(dst);
1096         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1097
1098         if (push_items <= 0) {
1099                 return 1;
1100         }
1101
1102         if (src_nritems < push_items)
1103                 push_items = src_nritems;
1104
1105         copy_extent_buffer(dst, src,
1106                            btrfs_node_key_ptr_offset(dst_nritems),
1107                            btrfs_node_key_ptr_offset(0),
1108                            push_items * sizeof(struct btrfs_key_ptr));
1109
1110         if (push_items < src_nritems) {
1111                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1112                                       btrfs_node_key_ptr_offset(push_items),
1113                                       (src_nritems - push_items) *
1114                                       sizeof(struct btrfs_key_ptr));
1115         }
1116         btrfs_set_header_nritems(src, src_nritems - push_items);
1117         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1118         btrfs_mark_buffer_dirty(src);
1119         btrfs_mark_buffer_dirty(dst);
1120         return ret;
1121 }
1122
1123 /*
1124  * try to push data from one node into the next node right in the
1125  * tree.
1126  *
1127  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1128  * error, and > 0 if there was no room in the right hand block.
1129  *
1130  * this will  only push up to 1/2 the contents of the left node over
1131  */
1132 static int balance_node_right(struct btrfs_trans_handle *trans,
1133                               struct btrfs_root *root,
1134                               struct extent_buffer *dst,
1135                               struct extent_buffer *src)
1136 {
1137         int push_items = 0;
1138         int max_push;
1139         int src_nritems;
1140         int dst_nritems;
1141         int ret = 0;
1142
1143         src_nritems = btrfs_header_nritems(src);
1144         dst_nritems = btrfs_header_nritems(dst);
1145         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1146         if (push_items <= 0)
1147                 return 1;
1148
1149         max_push = src_nritems / 2 + 1;
1150         /* don't try to empty the node */
1151         if (max_push >= src_nritems)
1152                 return 1;
1153
1154         if (max_push < push_items)
1155                 push_items = max_push;
1156
1157         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1158                                       btrfs_node_key_ptr_offset(0),
1159                                       (dst_nritems) *
1160                                       sizeof(struct btrfs_key_ptr));
1161
1162         copy_extent_buffer(dst, src,
1163                            btrfs_node_key_ptr_offset(0),
1164                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1165                            push_items * sizeof(struct btrfs_key_ptr));
1166
1167         btrfs_set_header_nritems(src, src_nritems - push_items);
1168         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1169
1170         btrfs_mark_buffer_dirty(src);
1171         btrfs_mark_buffer_dirty(dst);
1172         return ret;
1173 }
1174
1175 /*
1176  * helper function to insert a new root level in the tree.
1177  * A new node is allocated, and a single item is inserted to
1178  * point to the existing root
1179  *
1180  * returns zero on success or < 0 on failure.
1181  */
1182 static int insert_new_root(struct btrfs_trans_handle *trans,
1183                            struct btrfs_root *root,
1184                            struct btrfs_path *path, int level)
1185 {
1186         struct extent_buffer *lower;
1187         struct extent_buffer *c;
1188         struct btrfs_disk_key lower_key;
1189
1190         BUG_ON(path->nodes[level]);
1191         BUG_ON(path->nodes[level-1] != root->node);
1192
1193         c = btrfs_alloc_free_block(trans, root,
1194                                    extent_buffer_blocknr(root->node), 0);
1195         if (IS_ERR(c))
1196                 return PTR_ERR(c);
1197         memset_extent_buffer(c, 0, 0, root->nodesize);
1198         btrfs_set_header_nritems(c, 1);
1199         btrfs_set_header_level(c, level);
1200         btrfs_set_header_blocknr(c, extent_buffer_blocknr(c));
1201         btrfs_set_header_generation(c, trans->transid);
1202         btrfs_set_header_owner(c, root->root_key.objectid);
1203         lower = path->nodes[level-1];
1204
1205         write_extent_buffer(c, root->fs_info->fsid,
1206                             (unsigned long)btrfs_header_fsid(c),
1207                             BTRFS_FSID_SIZE);
1208         if (level == 1)
1209                 btrfs_item_key(lower, &lower_key, 0);
1210         else
1211                 btrfs_node_key(lower, &lower_key, 0);
1212         btrfs_set_node_key(c, &lower_key, 0);
1213         btrfs_set_node_blockptr(c, 0, extent_buffer_blocknr(lower));
1214
1215         btrfs_mark_buffer_dirty(c);
1216
1217         /* the super has an extra ref to root->node */
1218         free_extent_buffer(root->node);
1219         root->node = c;
1220         extent_buffer_get(c);
1221         path->nodes[level] = c;
1222         path->slots[level] = 0;
1223         return 0;
1224 }
1225
1226 /*
1227  * worker function to insert a single pointer in a node.
1228  * the node should have enough room for the pointer already
1229  *
1230  * slot and level indicate where you want the key to go, and
1231  * blocknr is the block the key points to.
1232  *
1233  * returns zero on success and < 0 on any error
1234  */
1235 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1236                       *root, struct btrfs_path *path, struct btrfs_disk_key
1237                       *key, u64 blocknr, int slot, int level)
1238 {
1239         struct extent_buffer *lower;
1240         int nritems;
1241
1242         BUG_ON(!path->nodes[level]);
1243         lower = path->nodes[level];
1244         nritems = btrfs_header_nritems(lower);
1245         if (slot > nritems)
1246                 BUG();
1247         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1248                 BUG();
1249         if (slot != nritems) {
1250                 memmove_extent_buffer(lower,
1251                               btrfs_node_key_ptr_offset(slot + 1),
1252                               btrfs_node_key_ptr_offset(slot),
1253                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1254         }
1255         btrfs_set_node_key(lower, key, slot);
1256         btrfs_set_node_blockptr(lower, slot, blocknr);
1257         btrfs_set_header_nritems(lower, nritems + 1);
1258         btrfs_mark_buffer_dirty(lower);
1259         check_node(root, path, level);
1260         return 0;
1261 }
1262
1263 /*
1264  * split the node at the specified level in path in two.
1265  * The path is corrected to point to the appropriate node after the split
1266  *
1267  * Before splitting this tries to make some room in the node by pushing
1268  * left and right, if either one works, it returns right away.
1269  *
1270  * returns 0 on success and < 0 on failure
1271  */
1272 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1273                       *root, struct btrfs_path *path, int level)
1274 {
1275         struct extent_buffer *c;
1276         struct extent_buffer *split;
1277         struct btrfs_disk_key disk_key;
1278         int mid;
1279         int ret;
1280         int wret;
1281         u32 c_nritems;
1282
1283         c = path->nodes[level];
1284         if (c == root->node) {
1285                 /* trying to split the root, lets make a new one */
1286                 ret = insert_new_root(trans, root, path, level + 1);
1287                 if (ret)
1288                         return ret;
1289         } else {
1290                 ret = push_nodes_for_insert(trans, root, path, level);
1291                 c = path->nodes[level];
1292                 if (!ret && btrfs_header_nritems(c) <
1293                     BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
1294                         return 0;
1295                 if (ret < 0)
1296                         return ret;
1297         }
1298
1299         c_nritems = btrfs_header_nritems(c);
1300         split = btrfs_alloc_free_block(trans, root,
1301                                        extent_buffer_blocknr(c), 0);
1302         if (IS_ERR(split))
1303                 return PTR_ERR(split);
1304
1305         btrfs_set_header_flags(split, btrfs_header_flags(c));
1306         btrfs_set_header_level(split, btrfs_header_level(c));
1307         btrfs_set_header_blocknr(split, extent_buffer_blocknr(split));
1308         btrfs_set_header_generation(split, trans->transid);
1309         btrfs_set_header_owner(split, root->root_key.objectid);
1310         write_extent_buffer(split, root->fs_info->fsid,
1311                             (unsigned long)btrfs_header_fsid(split),
1312                             BTRFS_FSID_SIZE);
1313
1314         mid = (c_nritems + 1) / 2;
1315
1316         copy_extent_buffer(split, c,
1317                            btrfs_node_key_ptr_offset(0),
1318                            btrfs_node_key_ptr_offset(mid),
1319                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1320         btrfs_set_header_nritems(split, c_nritems - mid);
1321         btrfs_set_header_nritems(c, mid);
1322         ret = 0;
1323
1324         btrfs_mark_buffer_dirty(c);
1325         btrfs_mark_buffer_dirty(split);
1326
1327         btrfs_node_key(split, &disk_key, 0);
1328         wret = insert_ptr(trans, root, path, &disk_key,
1329                           extent_buffer_blocknr(split),
1330                           path->slots[level + 1] + 1,
1331                           level + 1);
1332         if (wret)
1333                 ret = wret;
1334
1335         if (path->slots[level] >= mid) {
1336                 path->slots[level] -= mid;
1337                 free_extent_buffer(c);
1338                 path->nodes[level] = split;
1339                 path->slots[level + 1] += 1;
1340         } else {
1341                 free_extent_buffer(split);
1342         }
1343         return ret;
1344 }
1345
1346 /*
1347  * how many bytes are required to store the items in a leaf.  start
1348  * and nr indicate which items in the leaf to check.  This totals up the
1349  * space used both by the item structs and the item data
1350  */
1351 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1352 {
1353         int data_len;
1354         int nritems = btrfs_header_nritems(l);
1355         int end = min(nritems, start + nr) - 1;
1356
1357         if (!nr)
1358                 return 0;
1359         data_len = btrfs_item_end_nr(l, start);
1360         data_len = data_len - btrfs_item_offset_nr(l, end);
1361         data_len += sizeof(struct btrfs_item) * nr;
1362         WARN_ON(data_len < 0);
1363         return data_len;
1364 }
1365
1366 /*
1367  * The space between the end of the leaf items and
1368  * the start of the leaf data.  IOW, how much room
1369  * the leaf has left for both items and data
1370  */
1371 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1372 {
1373         int nritems = btrfs_header_nritems(leaf);
1374         int ret;
1375         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1376         if (ret < 0) {
1377                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1378                        ret, BTRFS_LEAF_DATA_SIZE(root),
1379                        leaf_space_used(leaf, 0, nritems), nritems);
1380         }
1381         return ret;
1382 }
1383
1384 /*
1385  * push some data in the path leaf to the right, trying to free up at
1386  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1387  *
1388  * returns 1 if the push failed because the other node didn't have enough
1389  * room, 0 if everything worked out and < 0 if there were major errors.
1390  */
1391 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1392                            *root, struct btrfs_path *path, int data_size)
1393 {
1394         struct extent_buffer *left = path->nodes[0];
1395         struct extent_buffer *right;
1396         struct extent_buffer *upper;
1397         struct btrfs_disk_key disk_key;
1398         int slot;
1399         int i;
1400         int free_space;
1401         int push_space = 0;
1402         int push_items = 0;
1403         struct btrfs_item *item;
1404         u32 left_nritems;
1405         u32 right_nritems;
1406         u32 data_end;
1407         int ret;
1408
1409         slot = path->slots[1];
1410         if (!path->nodes[1]) {
1411                 return 1;
1412         }
1413         upper = path->nodes[1];
1414         if (slot >= btrfs_header_nritems(upper) - 1)
1415                 return 1;
1416
1417         right = read_tree_block(root, btrfs_node_blockptr(upper, slot + 1));
1418         free_space = btrfs_leaf_free_space(root, right);
1419         if (free_space < data_size + sizeof(struct btrfs_item)) {
1420                 free_extent_buffer(right);
1421                 return 1;
1422         }
1423
1424         /* cow and double check */
1425         ret = btrfs_cow_block(trans, root, right, upper,
1426                               slot + 1, &right);
1427         if (ret) {
1428                 free_extent_buffer(right);
1429                 return 1;
1430         }
1431         free_space = btrfs_leaf_free_space(root, right);
1432         if (free_space < data_size + sizeof(struct btrfs_item)) {
1433                 free_extent_buffer(right);
1434                 return 1;
1435         }
1436
1437         left_nritems = btrfs_header_nritems(left);
1438         if (left_nritems == 0) {
1439                 free_extent_buffer(right);
1440                 return 1;
1441         }
1442
1443         for (i = left_nritems - 1; i >= 1; i--) {
1444                 item = btrfs_item_nr(left, i);
1445                 if (path->slots[0] == i)
1446                         push_space += data_size + sizeof(*item);
1447                 if (btrfs_item_size(left, item) + sizeof(*item) + push_space >
1448                     free_space)
1449                         break;
1450                 push_items++;
1451                 push_space += btrfs_item_size(left, item) + sizeof(*item);
1452         }
1453
1454         if (push_items == 0) {
1455                 free_extent_buffer(right);
1456                 return 1;
1457         }
1458
1459         if (push_items == left_nritems)
1460                 WARN_ON(1);
1461
1462         /* push left to right */
1463         right_nritems = btrfs_header_nritems(right);
1464         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1465         push_space -= leaf_data_end(root, left);
1466
1467         /* make room in the right data area */
1468         data_end = leaf_data_end(root, right);
1469         memmove_extent_buffer(right,
1470                               btrfs_leaf_data(right) + data_end - push_space,
1471                               btrfs_leaf_data(right) + data_end,
1472                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1473
1474         /* copy from the left data area */
1475         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1476                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1477                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1478                      push_space);
1479
1480         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1481                               btrfs_item_nr_offset(0),
1482                               right_nritems * sizeof(struct btrfs_item));
1483
1484         /* copy the items from left to right */
1485         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1486                    btrfs_item_nr_offset(left_nritems - push_items),
1487                    push_items * sizeof(struct btrfs_item));
1488
1489         /* update the item pointers */
1490         right_nritems += push_items;
1491         btrfs_set_header_nritems(right, right_nritems);
1492         push_space = BTRFS_LEAF_DATA_SIZE(root);
1493         for (i = 0; i < right_nritems; i++) {
1494                 item = btrfs_item_nr(right, i);
1495                 btrfs_set_item_offset(right, item, push_space -
1496                                       btrfs_item_size(right, item));
1497                 push_space = btrfs_item_offset(right, item);
1498         }
1499         left_nritems -= push_items;
1500         btrfs_set_header_nritems(left, left_nritems);
1501
1502         btrfs_mark_buffer_dirty(left);
1503         btrfs_mark_buffer_dirty(right);
1504
1505         btrfs_item_key(right, &disk_key, 0);
1506         btrfs_set_node_key(upper, &disk_key, slot + 1);
1507         btrfs_mark_buffer_dirty(upper);
1508
1509         /* then fixup the leaf pointer in the path */
1510         if (path->slots[0] >= left_nritems) {
1511                 path->slots[0] -= left_nritems;
1512                 free_extent_buffer(path->nodes[0]);
1513                 path->nodes[0] = right;
1514                 path->slots[1] += 1;
1515         } else {
1516                 free_extent_buffer(right);
1517         }
1518         if (path->nodes[1])
1519                 check_node(root, path, 1);
1520         return 0;
1521 }
1522 /*
1523  * push some data in the path leaf to the left, trying to free up at
1524  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1525  */
1526 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1527                           *root, struct btrfs_path *path, int data_size)
1528 {
1529         struct btrfs_disk_key disk_key;
1530         struct extent_buffer *right = path->nodes[0];
1531         struct extent_buffer *left;
1532         int slot;
1533         int i;
1534         int free_space;
1535         int push_space = 0;
1536         int push_items = 0;
1537         struct btrfs_item *item;
1538         u32 old_left_nritems;
1539         u32 right_nritems;
1540         int ret = 0;
1541         int wret;
1542
1543         slot = path->slots[1];
1544         if (slot == 0)
1545                 return 1;
1546         if (!path->nodes[1])
1547                 return 1;
1548
1549         left = read_tree_block(root, btrfs_node_blockptr(path->nodes[1],
1550                                                          slot - 1));
1551         free_space = btrfs_leaf_free_space(root, left);
1552         if (free_space < data_size + sizeof(struct btrfs_item)) {
1553                 free_extent_buffer(left);
1554                 return 1;
1555         }
1556
1557         /* cow and double check */
1558         ret = btrfs_cow_block(trans, root, left,
1559                               path->nodes[1], slot - 1, &left);
1560         if (ret) {
1561                 /* we hit -ENOSPC, but it isn't fatal here */
1562                 free_extent_buffer(left);
1563                 return 1;
1564         }
1565         free_space = btrfs_leaf_free_space(root, left);
1566         if (free_space < data_size + sizeof(struct btrfs_item)) {
1567                 free_extent_buffer(left);
1568                 return 1;
1569         }
1570
1571         right_nritems = btrfs_header_nritems(right);
1572         if (right_nritems == 0) {
1573                 free_extent_buffer(left);
1574                 return 1;
1575         }
1576
1577         for (i = 0; i < right_nritems - 1; i++) {
1578                 item = btrfs_item_nr(right, i);
1579                 if (path->slots[0] == i)
1580                         push_space += data_size + sizeof(*item);
1581                 if (btrfs_item_size(right, item) + sizeof(*item) + push_space >
1582                     free_space)
1583                         break;
1584                 push_items++;
1585                 push_space += btrfs_item_size(right, item) + sizeof(*item);
1586         }
1587         if (push_items == 0) {
1588                 free_extent_buffer(left);
1589                 return 1;
1590         }
1591         if (push_items == btrfs_header_nritems(right))
1592                 WARN_ON(1);
1593
1594         /* push data from right to left */
1595         copy_extent_buffer(left, right,
1596                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1597                            btrfs_item_nr_offset(0),
1598                            push_items * sizeof(struct btrfs_item));
1599
1600         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1601                      btrfs_item_offset_nr(right, push_items -1);
1602
1603         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1604                      leaf_data_end(root, left) - push_space,
1605                      btrfs_leaf_data(right) +
1606                      btrfs_item_offset_nr(right, push_items - 1),
1607                      push_space);
1608         old_left_nritems = btrfs_header_nritems(left);
1609         BUG_ON(old_left_nritems < 0);
1610
1611         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1612                 u32 ioff;
1613                 item = btrfs_item_nr(left, i);
1614                 ioff = btrfs_item_offset(left, item);
1615                 btrfs_set_item_offset(left, item,
1616                       ioff - (BTRFS_LEAF_DATA_SIZE(root) -
1617                       btrfs_item_offset_nr(left, old_left_nritems - 1)));
1618         }
1619         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1620
1621         /* fixup right node */
1622         push_space = btrfs_item_offset_nr(right, push_items - 1) -
1623                                           leaf_data_end(root, right);
1624         memmove_extent_buffer(right, btrfs_leaf_data(right) +
1625                               BTRFS_LEAF_DATA_SIZE(root) - push_space,
1626                               btrfs_leaf_data(right) +
1627                               leaf_data_end(root, right), push_space);
1628
1629         memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1630                               btrfs_item_nr_offset(push_items),
1631                              (btrfs_header_nritems(right) - push_items) *
1632                              sizeof(struct btrfs_item));
1633
1634         right_nritems = btrfs_header_nritems(right) - push_items;
1635         btrfs_set_header_nritems(right, right_nritems);
1636         push_space = BTRFS_LEAF_DATA_SIZE(root);
1637
1638         for (i = 0; i < right_nritems; i++) {
1639                 item = btrfs_item_nr(right, i);
1640                 btrfs_set_item_offset(right, item, push_space -
1641                                       btrfs_item_size(right, item));
1642                 push_space = btrfs_item_offset(right, item);
1643         }
1644
1645         btrfs_mark_buffer_dirty(left);
1646         btrfs_mark_buffer_dirty(right);
1647
1648         btrfs_item_key(right, &disk_key, 0);
1649         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1650         if (wret)
1651                 ret = wret;
1652
1653         /* then fixup the leaf pointer in the path */
1654         if (path->slots[0] < push_items) {
1655                 path->slots[0] += old_left_nritems;
1656                 free_extent_buffer(path->nodes[0]);
1657                 path->nodes[0] = left;
1658                 path->slots[1] -= 1;
1659         } else {
1660                 free_extent_buffer(left);
1661                 path->slots[0] -= push_items;
1662         }
1663         BUG_ON(path->slots[0] < 0);
1664         if (path->nodes[1])
1665                 check_node(root, path, 1);
1666         return ret;
1667 }
1668
1669 /*
1670  * split the path's leaf in two, making sure there is at least data_size
1671  * available for the resulting leaf level of the path.
1672  *
1673  * returns 0 if all went well and < 0 on failure.
1674  */
1675 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1676                       *root, struct btrfs_key *ins_key,
1677                       struct btrfs_path *path, int data_size)
1678 {
1679         struct extent_buffer *l;
1680         u32 nritems;
1681         int mid;
1682         int slot;
1683         struct extent_buffer *right;
1684         int space_needed = data_size + sizeof(struct btrfs_item);
1685         int data_copy_size;
1686         int rt_data_off;
1687         int i;
1688         int ret = 0;
1689         int wret;
1690         int double_split = 0;
1691         struct btrfs_disk_key disk_key;
1692
1693         /* first try to make some room by pushing left and right */
1694         wret = push_leaf_left(trans, root, path, data_size);
1695         if (wret < 0)
1696                 return wret;
1697         if (wret) {
1698                 wret = push_leaf_right(trans, root, path, data_size);
1699                 if (wret < 0)
1700                         return wret;
1701         }
1702         l = path->nodes[0];
1703
1704         /* did the pushes work? */
1705         if (btrfs_leaf_free_space(root, l) >=
1706             sizeof(struct btrfs_item) + data_size)
1707                 return 0;
1708
1709         if (!path->nodes[1]) {
1710                 ret = insert_new_root(trans, root, path, 1);
1711                 if (ret)
1712                         return ret;
1713         }
1714         slot = path->slots[0];
1715         nritems = btrfs_header_nritems(l);
1716         mid = (nritems + 1)/ 2;
1717
1718         right = btrfs_alloc_free_block(trans, root,
1719                                               extent_buffer_blocknr(l), 0);
1720         if (IS_ERR(right))
1721                 return PTR_ERR(right);
1722
1723         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1724         btrfs_set_header_blocknr(right, extent_buffer_blocknr(right));
1725         btrfs_set_header_generation(right, trans->transid);
1726         btrfs_set_header_owner(right, root->root_key.objectid);
1727         btrfs_set_header_level(right, 0);
1728         write_extent_buffer(right, root->fs_info->fsid,
1729                             (unsigned long)btrfs_header_fsid(right),
1730                             BTRFS_FSID_SIZE);
1731
1732         if (mid <= slot) {
1733                 if (nritems == 1 ||
1734                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1735                         BTRFS_LEAF_DATA_SIZE(root)) {
1736                         if (slot >= nritems) {
1737                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1738                                 btrfs_set_header_nritems(right, 0);
1739                                 wret = insert_ptr(trans, root, path,
1740                                                   &disk_key,
1741                                                   extent_buffer_blocknr(right),
1742                                                   path->slots[1] + 1, 1);
1743                                 if (wret)
1744                                         ret = wret;
1745                                 free_extent_buffer(path->nodes[0]);
1746                                 path->nodes[0] = right;
1747                                 path->slots[0] = 0;
1748                                 path->slots[1] += 1;
1749                                 return ret;
1750                         }
1751                         mid = slot;
1752                         double_split = 1;
1753                 }
1754         } else {
1755                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1756                         BTRFS_LEAF_DATA_SIZE(root)) {
1757                         if (slot == 0) {
1758                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1759                                 btrfs_set_header_nritems(right, 0);
1760                                 wret = insert_ptr(trans, root, path,
1761                                                   &disk_key,
1762                                                   extent_buffer_blocknr(right),
1763                                                   path->slots[1], 1);
1764                                 if (wret)
1765                                         ret = wret;
1766                                 free_extent_buffer(path->nodes[0]);
1767                                 path->nodes[0] = right;
1768                                 path->slots[0] = 0;
1769                                 if (path->slots[1] == 0) {
1770                                         wret = fixup_low_keys(trans, root,
1771                                                    path, &disk_key, 1);
1772                                         if (wret)
1773                                                 ret = wret;
1774                                 }
1775                                 return ret;
1776                         }
1777                         mid = slot;
1778                         double_split = 1;
1779                 }
1780         }
1781         nritems = nritems - mid;
1782         btrfs_set_header_nritems(right, nritems);
1783         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
1784
1785         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
1786                            btrfs_item_nr_offset(mid),
1787                            nritems * sizeof(struct btrfs_item));
1788
1789         copy_extent_buffer(right, l,
1790                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1791                      data_copy_size, btrfs_leaf_data(l) +
1792                      leaf_data_end(root, l), data_copy_size);
1793
1794         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1795                       btrfs_item_end_nr(l, mid);
1796
1797         for (i = 0; i < nritems; i++) {
1798                 struct btrfs_item *item = btrfs_item_nr(right, i);
1799                 u32 ioff = btrfs_item_offset(right, item);
1800                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
1801         }
1802
1803         btrfs_set_header_nritems(l, mid);
1804         ret = 0;
1805         btrfs_item_key(right, &disk_key, 0);
1806         wret = insert_ptr(trans, root, path, &disk_key,
1807                           extent_buffer_blocknr(right), path->slots[1] + 1, 1);
1808         if (wret)
1809                 ret = wret;
1810
1811         btrfs_mark_buffer_dirty(right);
1812         btrfs_mark_buffer_dirty(l);
1813         BUG_ON(path->slots[0] != slot);
1814
1815         if (mid <= slot) {
1816                 free_extent_buffer(path->nodes[0]);
1817                 path->nodes[0] = right;
1818                 path->slots[0] -= mid;
1819                 path->slots[1] += 1;
1820         } else
1821                 free_extent_buffer(right);
1822
1823         BUG_ON(path->slots[0] < 0);
1824         check_node(root, path, 1);
1825         check_leaf(root, path, 0);
1826
1827         if (!double_split)
1828                 return ret;
1829
1830         right = btrfs_alloc_free_block(trans, root,
1831                                        extent_buffer_blocknr(l), 0);
1832         if (IS_ERR(right))
1833                 return PTR_ERR(right);
1834
1835         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1836         btrfs_set_header_blocknr(right, extent_buffer_blocknr(right));
1837         btrfs_set_header_generation(right, trans->transid);
1838         btrfs_set_header_owner(right, root->root_key.objectid);
1839         btrfs_set_header_level(right, 0);
1840         write_extent_buffer(right, root->fs_info->fsid,
1841                             (unsigned long)btrfs_header_fsid(right),
1842                             BTRFS_FSID_SIZE);
1843
1844         btrfs_cpu_key_to_disk(&disk_key, ins_key);
1845         btrfs_set_header_nritems(right, 0);
1846         wret = insert_ptr(trans, root, path,
1847                           &disk_key,
1848                           extent_buffer_blocknr(right),
1849                           path->slots[1], 1);
1850         if (wret)
1851                 ret = wret;
1852         if (path->slots[1] == 0) {
1853                 wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1854                 if (wret)
1855                         ret = wret;
1856         }
1857         free_extent_buffer(path->nodes[0]);
1858         path->nodes[0] = right;
1859         path->slots[0] = 0;
1860         check_node(root, path, 1);
1861         check_leaf(root, path, 0);
1862         return ret;
1863 }
1864
1865 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
1866                         struct btrfs_root *root,
1867                         struct btrfs_path *path,
1868                         u32 new_size)
1869 {
1870         int ret = 0;
1871         int slot;
1872         int slot_orig;
1873         struct extent_buffer *leaf;
1874         struct btrfs_item *item;
1875         u32 nritems;
1876         unsigned int data_end;
1877         unsigned int old_data_start;
1878         unsigned int old_size;
1879         unsigned int size_diff;
1880         int i;
1881
1882         slot_orig = path->slots[0];
1883         leaf = path->nodes[0];
1884
1885         nritems = btrfs_header_nritems(leaf);
1886         data_end = leaf_data_end(root, leaf);
1887
1888         slot = path->slots[0];
1889         old_data_start = btrfs_item_offset_nr(leaf, slot);
1890         old_size = btrfs_item_size_nr(leaf, slot);
1891         BUG_ON(old_size <= new_size);
1892         size_diff = old_size - new_size;
1893
1894         BUG_ON(slot < 0);
1895         BUG_ON(slot >= nritems);
1896
1897         /*
1898          * item0..itemN ... dataN.offset..dataN.size .. data0.size
1899          */
1900         /* first correct the data pointers */
1901         for (i = slot; i < nritems; i++) {
1902                 u32 ioff;
1903                 item = btrfs_item_nr(leaf, i);
1904                 ioff = btrfs_item_offset(leaf, item);
1905                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
1906         }
1907         /* shift the data */
1908         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
1909                       data_end + size_diff, btrfs_leaf_data(leaf) +
1910                       data_end, old_data_start + new_size - data_end);
1911
1912         item = btrfs_item_nr(leaf, slot);
1913         btrfs_set_item_size(leaf, item, new_size);
1914         btrfs_mark_buffer_dirty(leaf);
1915
1916         ret = 0;
1917         if (btrfs_leaf_free_space(root, leaf) < 0) {
1918                 btrfs_print_leaf(root, leaf);
1919                 BUG();
1920         }
1921         check_leaf(root, path, 0);
1922         return ret;
1923 }
1924
1925 int btrfs_extend_item(struct btrfs_trans_handle *trans,
1926                       struct btrfs_root *root, struct btrfs_path *path,
1927                       u32 data_size)
1928 {
1929         int ret = 0;
1930         int slot;
1931         int slot_orig;
1932         struct extent_buffer *leaf;
1933         struct btrfs_item *item;
1934         u32 nritems;
1935         unsigned int data_end;
1936         unsigned int old_data;
1937         unsigned int old_size;
1938         int i;
1939
1940         slot_orig = path->slots[0];
1941         leaf = path->nodes[0];
1942
1943         nritems = btrfs_header_nritems(leaf);
1944         data_end = leaf_data_end(root, leaf);
1945
1946         if (btrfs_leaf_free_space(root, leaf) < data_size) {
1947                 btrfs_print_leaf(root, leaf);
1948                 BUG();
1949         }
1950         slot = path->slots[0];
1951         old_data = btrfs_item_end_nr(leaf, slot);
1952
1953         BUG_ON(slot < 0);
1954         BUG_ON(slot >= nritems);
1955
1956         /*
1957          * item0..itemN ... dataN.offset..dataN.size .. data0.size
1958          */
1959         /* first correct the data pointers */
1960         for (i = slot; i < nritems; i++) {
1961                 u32 ioff;
1962                 item = btrfs_item_nr(leaf, i);
1963                 ioff = btrfs_item_offset(leaf, item);
1964                 btrfs_set_item_offset(leaf, item, ioff - data_size);
1965         }
1966
1967         /* shift the data */
1968         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
1969                       data_end - data_size, btrfs_leaf_data(leaf) +
1970                       data_end, old_data - data_end);
1971
1972         data_end = old_data;
1973         old_size = btrfs_item_size_nr(leaf, slot);
1974         item = btrfs_item_nr(leaf, slot);
1975         btrfs_set_item_size(leaf, item, old_size + data_size);
1976         btrfs_mark_buffer_dirty(leaf);
1977
1978         ret = 0;
1979         if (btrfs_leaf_free_space(root, leaf) < 0) {
1980                 btrfs_print_leaf(root, leaf);
1981                 BUG();
1982         }
1983         check_leaf(root, path, 0);
1984         return ret;
1985 }
1986
1987 /*
1988  * Given a key and some data, insert an item into the tree.
1989  * This does all the path init required, making room in the tree if needed.
1990  */
1991 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans,
1992                             struct btrfs_root *root,
1993                             struct btrfs_path *path,
1994                             struct btrfs_key *cpu_key, u32 data_size)
1995 {
1996         struct extent_buffer *leaf;
1997         struct btrfs_item *item;
1998         int ret = 0;
1999         int slot;
2000         int slot_orig;
2001         u32 nritems;
2002         unsigned int data_end;
2003         struct btrfs_disk_key disk_key;
2004
2005         btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2006
2007         /* create a root if there isn't one */
2008         if (!root->node)
2009                 BUG();
2010
2011         ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
2012         if (ret == 0) {
2013                 return -EEXIST;
2014         }
2015         if (ret < 0)
2016                 goto out;
2017
2018         slot_orig = path->slots[0];
2019         leaf = path->nodes[0];
2020
2021         nritems = btrfs_header_nritems(leaf);
2022         data_end = leaf_data_end(root, leaf);
2023
2024         if (btrfs_leaf_free_space(root, leaf) <
2025             sizeof(struct btrfs_item) + data_size) {
2026                 BUG();
2027         }
2028
2029         slot = path->slots[0];
2030         BUG_ON(slot < 0);
2031
2032         if (slot != nritems) {
2033                 int i;
2034                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2035
2036                 if (old_data < data_end) {
2037                         btrfs_print_leaf(root, leaf);
2038                         printk("slot %d old_data %d data_end %d\n",
2039                                slot, old_data, data_end);
2040                         BUG_ON(1);
2041                 }
2042                 /*
2043                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2044                  */
2045                 /* first correct the data pointers */
2046                 for (i = slot; i < nritems; i++) {
2047                         u32 ioff;
2048                         item = btrfs_item_nr(leaf, i);
2049                         ioff = btrfs_item_offset(leaf, item);
2050                         btrfs_set_item_offset(leaf, item, ioff - data_size);
2051                 }
2052
2053                 /* shift the items */
2054                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
2055                               btrfs_item_nr_offset(slot),
2056                               (nritems - slot) * sizeof(struct btrfs_item));
2057
2058                 /* shift the data */
2059                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2060                               data_end - data_size, btrfs_leaf_data(leaf) +
2061                               data_end, old_data - data_end);
2062                 data_end = old_data;
2063         }
2064
2065         /* setup the item for the new data */
2066         btrfs_set_item_key(leaf, &disk_key, slot);
2067         item = btrfs_item_nr(leaf, slot);
2068         btrfs_set_item_offset(leaf, item, data_end - data_size);
2069         btrfs_set_item_size(leaf, item, data_size);
2070         btrfs_set_header_nritems(leaf, nritems + 1);
2071         btrfs_mark_buffer_dirty(leaf);
2072
2073         ret = 0;
2074         if (slot == 0)
2075                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2076
2077         if (btrfs_leaf_free_space(root, leaf) < 0) {
2078                 btrfs_print_leaf(root, leaf);
2079                 BUG();
2080         }
2081         check_leaf(root, path, 0);
2082 out:
2083         return ret;
2084 }
2085
2086 /*
2087  * Given a key and some data, insert an item into the tree.
2088  * This does all the path init required, making room in the tree if needed.
2089  */
2090 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2091                       *root, struct btrfs_key *cpu_key, void *data, u32
2092                       data_size)
2093 {
2094         int ret = 0;
2095         struct btrfs_path *path;
2096         struct extent_buffer *leaf;
2097         unsigned long ptr;
2098
2099         path = btrfs_alloc_path();
2100         BUG_ON(!path);
2101         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2102         if (!ret) {
2103                 leaf = path->nodes[0];
2104                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2105                 write_extent_buffer(leaf, data, ptr, data_size);
2106                 btrfs_mark_buffer_dirty(leaf);
2107         }
2108         btrfs_free_path(path);
2109         return ret;
2110 }
2111
2112 /*
2113  * delete the pointer from a given node.
2114  *
2115  * If the delete empties a node, the node is removed from the tree,
2116  * continuing all the way the root if required.  The root is converted into
2117  * a leaf if all the nodes are emptied.
2118  */
2119 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2120                    struct btrfs_path *path, int level, int slot)
2121 {
2122         struct extent_buffer *parent = path->nodes[level];
2123         u32 nritems;
2124         int ret = 0;
2125         int wret;
2126
2127         nritems = btrfs_header_nritems(parent);
2128         if (slot != nritems -1) {
2129                 memmove_extent_buffer(parent,
2130                               btrfs_node_key_ptr_offset(slot),
2131                               btrfs_node_key_ptr_offset(slot + 1),
2132                               sizeof(struct btrfs_key_ptr) *
2133                               (nritems - slot - 1));
2134         }
2135         nritems--;
2136         btrfs_set_header_nritems(parent, nritems);
2137         if (nritems == 0 && parent == root->node) {
2138                 BUG_ON(btrfs_header_level(root->node) != 1);
2139                 /* just turn the root into a leaf and break */
2140                 btrfs_set_header_level(root->node, 0);
2141         } else if (slot == 0) {
2142                 struct btrfs_disk_key disk_key;
2143
2144                 btrfs_node_key(parent, &disk_key, 0);
2145                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2146                 if (wret)
2147                         ret = wret;
2148         }
2149         btrfs_mark_buffer_dirty(parent);
2150         return ret;
2151 }
2152
2153 /*
2154  * delete the item at the leaf level in path.  If that empties
2155  * the leaf, remove it from the tree
2156  */
2157 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2158                    struct btrfs_path *path)
2159 {
2160         int slot;
2161         struct extent_buffer *leaf;
2162         struct btrfs_item *item;
2163         int doff;
2164         int dsize;
2165         int ret = 0;
2166         int wret;
2167         u32 nritems;
2168
2169         leaf = path->nodes[0];
2170         slot = path->slots[0];
2171         doff = btrfs_item_offset_nr(leaf, slot);
2172         dsize = btrfs_item_size_nr(leaf, slot);
2173         nritems = btrfs_header_nritems(leaf);
2174
2175         if (slot != nritems - 1) {
2176                 int i;
2177                 int data_end = leaf_data_end(root, leaf);
2178
2179                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2180                               data_end + dsize,
2181                               btrfs_leaf_data(leaf) + data_end,
2182                               doff - data_end);
2183
2184                 for (i = slot + 1; i < nritems; i++) {
2185                         u32 ioff;
2186                         item = btrfs_item_nr(leaf, i);
2187                         ioff = btrfs_item_offset(leaf, item);
2188                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2189                 }
2190                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2191                               btrfs_item_nr_offset(slot + 1),
2192                               sizeof(struct btrfs_item) *
2193                               (nritems - slot - 1));
2194         }
2195         btrfs_set_header_nritems(leaf, nritems - 1);
2196         nritems--;
2197
2198         /* delete the leaf if we've emptied it */
2199         if (nritems == 0) {
2200                 if (leaf == root->node) {
2201                         btrfs_set_header_level(leaf, 0);
2202                 } else {
2203                         clean_tree_block(trans, root, leaf);
2204                         wait_on_tree_block_writeback(root, leaf);
2205                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
2206                         if (wret)
2207                                 ret = wret;
2208                         wret = btrfs_free_extent(trans, root,
2209                                                  extent_buffer_blocknr(leaf),
2210                                                  1, 1);
2211                         if (wret)
2212                                 ret = wret;
2213                 }
2214         } else {
2215                 int used = leaf_space_used(leaf, 0, nritems);
2216                 if (slot == 0) {
2217                         struct btrfs_disk_key disk_key;
2218
2219                         btrfs_item_key(leaf, &disk_key, 0);
2220                         wret = fixup_low_keys(trans, root, path,
2221                                               &disk_key, 1);
2222                         if (wret)
2223                                 ret = wret;
2224                 }
2225
2226                 /* delete the leaf if it is mostly empty */
2227                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
2228                         /* push_leaf_left fixes the path.
2229                          * make sure the path still points to our leaf
2230                          * for possible call to del_ptr below
2231                          */
2232                         slot = path->slots[1];
2233                         extent_buffer_get(leaf);
2234
2235                         wret = push_leaf_left(trans, root, path, 1);
2236                         if (wret < 0 && wret != -ENOSPC)
2237                                 ret = wret;
2238
2239                         if (path->nodes[0] == leaf &&
2240                             btrfs_header_nritems(leaf)) {
2241                                 wret = push_leaf_right(trans, root, path, 1);
2242                                 if (wret < 0 && wret != -ENOSPC)
2243                                         ret = wret;
2244                         }
2245
2246                         if (btrfs_header_nritems(leaf) == 0) {
2247                                 u64 blocknr = extent_buffer_blocknr(leaf);
2248
2249                                 clean_tree_block(trans, root, leaf);
2250                                 wait_on_tree_block_writeback(root, leaf);
2251
2252                                 wret = del_ptr(trans, root, path, 1, slot);
2253                                 if (wret)
2254                                         ret = wret;
2255
2256                                 free_extent_buffer(leaf);
2257                                 wret = btrfs_free_extent(trans, root, blocknr,
2258                                                          1, 1);
2259                                 if (wret)
2260                                         ret = wret;
2261                         } else {
2262                                 btrfs_mark_buffer_dirty(leaf);
2263                                 free_extent_buffer(leaf);
2264                         }
2265                 } else {
2266                         btrfs_mark_buffer_dirty(leaf);
2267                 }
2268         }
2269         return ret;
2270 }
2271
2272 /*
2273  * walk up the tree as far as required to find the next leaf.
2274  * returns 0 if it found something or 1 if there are no greater leaves.
2275  * returns < 0 on io errors.
2276  */
2277 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2278 {
2279         int slot;
2280         int level = 1;
2281         u64 blocknr;
2282         struct extent_buffer *c;
2283         struct extent_buffer *next = NULL;
2284
2285         while(level < BTRFS_MAX_LEVEL) {
2286                 if (!path->nodes[level])
2287                         return 1;
2288
2289                 slot = path->slots[level] + 1;
2290                 c = path->nodes[level];
2291                 if (slot >= btrfs_header_nritems(c)) {
2292                         level++;
2293                         continue;
2294                 }
2295
2296                 blocknr = btrfs_node_blockptr(c, slot);
2297                 if (next)
2298                         free_extent_buffer(next);
2299
2300                 if (path->reada)
2301                         reada_for_search(root, path, level, slot);
2302
2303                 next = read_tree_block(root, blocknr);
2304                 break;
2305         }
2306         path->slots[level] = slot;
2307         while(1) {
2308                 level--;
2309                 c = path->nodes[level];
2310                 free_extent_buffer(c);
2311                 path->nodes[level] = next;
2312                 path->slots[level] = 0;
2313                 if (!level)
2314                         break;
2315                 if (path->reada)
2316                         reada_for_search(root, path, level, 0);
2317                 next = read_tree_block(root, btrfs_node_blockptr(next, 0));
2318         }
2319         return 0;
2320 }