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/sched.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, buf->len,
  87                                      search_start, empty_size);
  88         if (IS_ERR(cow))
  89                 return PTR_ERR(cow);
  90
  91         copy_extent_buffer(cow, buf, 0, 0, cow->len);
  92         btrfs_set_header_bytenr(cow, cow->start);
  93         btrfs_set_header_generation(cow, trans->transid);
  94         btrfs_set_header_owner(cow, root->root_key.objectid);
  95
  96         WARN_ON(btrfs_header_generation(buf) > trans->transid);
  97         if (btrfs_header_generation(buf) != trans->transid) {
  98                 different_trans = 1;
  99                 ret = btrfs_inc_ref(trans, root, buf);
 100                 if (ret)
 101                         return ret;
 102         } else {
 103                 clean_tree_block(trans, root, buf);
 104         }
 105
 106         if (buf == root->node) {
 107                 root->node = cow;
 108                 extent_buffer_get(cow);
 109                 if (buf != root->commit_root) {
 110                         btrfs_free_extent(trans, root, buf->start,
 111                                           buf->len, 1);
 112                 }
 113                 free_extent_buffer(buf);
 114         } else {
 115                 btrfs_set_node_blockptr(parent, parent_slot,
 116                                         cow->start);
 117                 btrfs_mark_buffer_dirty(parent);
 118                 WARN_ON(btrfs_header_generation(parent) != trans->transid);
 119                 btrfs_free_extent(trans, root, buf->start, buf->len, 1);
 120         }
 121         free_extent_buffer(buf);
 122         btrfs_mark_buffer_dirty(cow);
 123         *cow_ret = cow;
 124         return 0;
 125 }
 126
 127 int btrfs_cow_block(struct btrfs_trans_handle *trans,
 128                     struct btrfs_root *root, struct extent_buffer *buf,
 129                     struct extent_buffer *parent, int parent_slot,
 130                     struct extent_buffer **cow_ret)
 131 {
 132         u64 search_start;
 133         int ret;
 134         if (trans->transaction != root->fs_info->running_transaction) {
 135                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 136                        root->fs_info->running_transaction->transid);
 137                 WARN_ON(1);
 138         }
 139         if (trans->transid != root->fs_info->generation) {
 140                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 141                        root->fs_info->generation);
 142                 WARN_ON(1);
 143         }
 144         if (btrfs_header_generation(buf) == trans->transid) {
 145                 *cow_ret = buf;
 146                 return 0;
 147         }
 148
 149         search_start = buf->start & ~((u64)BTRFS_BLOCK_GROUP_SIZE - 1);
 150         ret = __btrfs_cow_block(trans, root, buf, parent,
 151                                  parent_slot, cow_ret, search_start, 0);
 152         return ret;
 153 }
 154
 155 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 156 {
 157         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 158                 return 1;
 159         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 160                 return 1;
 161         return 0;
 162 }
 163
 164 static int should_defrag_leaf(struct extent_buffer *leaf)
 165 {
 166         struct btrfs_key key;
 167         u32 nritems;
 168
 169         if (btrfs_buffer_defrag(leaf))
 170                 return 1;
 171
 172         nritems = btrfs_header_nritems(leaf);
 173         if (nritems == 0)
 174                 return 0;
 175
 176         btrfs_item_key_to_cpu(leaf, &key, 0);
 177         if (key.type == BTRFS_DIR_ITEM_KEY)
 178                 return 1;
 179
 180
 181         btrfs_item_key_to_cpu(leaf, &key, nritems - 1);
 182         if (key.type == BTRFS_DIR_ITEM_KEY)
 183                 return 1;
 184         if (nritems > 4) {
 185                 btrfs_item_key_to_cpu(leaf, &key, nritems / 2);
 186                 if (key.type == BTRFS_DIR_ITEM_KEY)
 187                         return 1;
 188         }
 189         return 0;
 190 }
 191
 192 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 193                        struct btrfs_root *root, struct extent_buffer *parent,
 194                        int start_slot, int cache_only, u64 *last_ret,
 195                        struct btrfs_key *progress)
 196 {
 197         struct extent_buffer *cur;
 198         struct extent_buffer *tmp;
 199         u64 blocknr;
 200         u64 search_start = *last_ret;
 201         u64 last_block = 0;
 202         u64 other;
 203         u32 parent_nritems;
 204         int end_slot;
 205         int i;
 206         int err = 0;
 207         int parent_level;
 208         int uptodate;
 209         u32 blocksize;
 210
 211         if (trans->transaction != root->fs_info->running_transaction) {
 212                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 213                        root->fs_info->running_transaction->transid);
 214                 WARN_ON(1);
 215         }
 216         if (trans->transid != root->fs_info->generation) {
 217                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 218                        root->fs_info->generation);
 219                 WARN_ON(1);
 220         }
 221         parent_level = btrfs_header_level(parent);
 222
 223         parent_nritems = btrfs_header_nritems(parent);
 224         blocksize = btrfs_level_size(root, parent_level - 1);
 225         end_slot = parent_nritems;
 226
 227         if (parent_nritems == 1)
 228                 return 0;
 229
 230         if (root != root->fs_info->extent_root) {
 231                 struct btrfs_key first_key;
 232                 struct btrfs_key last_key;
 233
 234                 btrfs_node_key_to_cpu(parent, &first_key, 0);
 235                 btrfs_node_key_to_cpu(parent, &last_key, parent_nritems - 1);
 236                 if (first_key.objectid != last_key.objectid)
 237                         return 0;
 238         }
 239
 240         for (i = start_slot; i < end_slot; i++) {
 241                 int close = 1;
 242
 243                 blocknr = btrfs_node_blockptr(parent, i);
 244                 if (last_block == 0)
 245                         last_block = blocknr;
 246                 if (i > 0) {
 247                         other = btrfs_node_blockptr(parent, i - 1);
 248                         close = close_blocks(blocknr, other, blocksize);
 249                 }
 250                 if (close && i < end_slot - 1) {
 251                         other = btrfs_node_blockptr(parent, i + 1);
 252                         close = close_blocks(blocknr, other, blocksize);
 253                 }
 254                 if (close) {
 255                         last_block = blocknr;
 256                         continue;
 257                 }
 258
 259                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
 260                 if (cur)
 261                         uptodate = btrfs_buffer_uptodate(cur);
 262                 else
 263                         uptodate = 0;
 264                 if (!cur || !uptodate ||
 265                     (parent_level != 1 && !btrfs_buffer_defrag(cur)) ||
 266                     (parent_level == 1 && !should_defrag_leaf(cur))) {
 267                         if (cache_only) {
 268                                 free_extent_buffer(cur);
 269                                 continue;
 270                         }
 271                         if (!cur) {
 272                                 cur = read_tree_block(root, blocknr,
 273                                                          blocksize);
 274                         } else if (!uptodate) {
 275                                 btrfs_read_buffer(cur);
 276                         }
 277                 }
 278                 if (search_start == 0)
 279                         search_start = last_block;
 280
 281                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 282                                         &tmp, search_start,
 283                                         min(16 * blocksize,
 284                                             (end_slot - i) * blocksize));
 285                 if (err) {
 286                         free_extent_buffer(cur);
 287                         break;
 288                 }
 289                 search_start = tmp->start;
 290                 *last_ret = search_start;
 291                 if (parent_level == 1)
 292                         btrfs_clear_buffer_defrag(tmp);
 293                 free_extent_buffer(tmp);
 294         }
 295         return err;
 296 }
 297
 298 /*
 299  * The leaf data grows from end-to-front in the node.
 300  * this returns the address of the start of the last item,
 301  * which is the stop of the leaf data stack
 302  */
 303 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 304                                          struct extent_buffer *leaf)
 305 {
 306         u32 nr = btrfs_header_nritems(leaf);
 307         if (nr == 0)
 308                 return BTRFS_LEAF_DATA_SIZE(root);
 309         return btrfs_item_offset_nr(leaf, nr - 1);
 310 }
 311
 312 /*
 313  * compare two keys in a memcmp fashion
 314  */
 315 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 316 {
 317         struct btrfs_key k1;
 318
 319         btrfs_disk_key_to_cpu(&k1, disk);
 320
 321         if (k1.objectid > k2->objectid)
 322                 return 1;
 323         if (k1.objectid < k2->objectid)
 324                 return -1;
 325         if (k1.type > k2->type)
 326                 return 1;
 327         if (k1.type < k2->type)
 328                 return -1;
 329         if (k1.offset > k2->offset)
 330                 return 1;
 331         if (k1.offset < k2->offset)
 332                 return -1;
 333         return 0;
 334 }
 335
 336 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 337                       int level)
 338 {
 339         struct extent_buffer *parent = NULL;
 340         struct extent_buffer *node = path->nodes[level];
 341         struct btrfs_disk_key parent_key;
 342         struct btrfs_disk_key node_key;
 343         int parent_slot;
 344         int slot;
 345         struct btrfs_key cpukey;
 346         u32 nritems = btrfs_header_nritems(node);
 347
 348         if (path->nodes[level + 1])
 349                 parent = path->nodes[level + 1];
 350
 351         slot = path->slots[level];
 352         BUG_ON(nritems == 0);
 353         if (parent) {
 354                 parent_slot = path->slots[level + 1];
 355                 btrfs_node_key(parent, &parent_key, parent_slot);
 356                 btrfs_node_key(node, &node_key, 0);
 357                 BUG_ON(memcmp(&parent_key, &node_key,
 358                               sizeof(struct btrfs_disk_key)));
 359                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 360                        btrfs_header_bytenr(node));
 361         }
 362         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 363         if (slot != 0) {
 364                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 365                 btrfs_node_key(node, &node_key, slot);
 366                 BUG_ON(comp_keys(&node_key, &cpukey) <= 0);
 367         }
 368         if (slot < nritems - 1) {
 369                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 370                 btrfs_node_key(node, &node_key, slot);
 371                 BUG_ON(comp_keys(&node_key, &cpukey) >= 0);
 372         }
 373         return 0;
 374 }
 375
 376 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 377                       int level)
 378 {
 379         struct extent_buffer *leaf = path->nodes[level];
 380         struct extent_buffer *parent = NULL;
 381         int parent_slot;
 382         struct btrfs_key cpukey;
 383         struct btrfs_disk_key parent_key;
 384         struct btrfs_disk_key leaf_key;
 385         int slot = path->slots[0];
 386
 387         u32 nritems = btrfs_header_nritems(leaf);
 388
 389         if (path->nodes[level + 1])
 390                 parent = path->nodes[level + 1];
 391
 392         if (nritems == 0)
 393                 return 0;
 394
 395         if (parent) {
 396                 parent_slot = path->slots[level + 1];
 397                 btrfs_node_key(parent, &parent_key, parent_slot);
 398                 btrfs_item_key(leaf, &leaf_key, 0);
 399
 400                 BUG_ON(memcmp(&parent_key, &leaf_key,
 401                        sizeof(struct btrfs_disk_key)));
 402                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 403                        btrfs_header_bytenr(leaf));
 404         }
 405 #if 0
 406         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 407                 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
 408                 btrfs_item_key(leaf, &leaf_key, i);
 409                 if (comp_keys(&leaf_key, &cpukey) >= 0) {
 410                         btrfs_print_leaf(root, leaf);
 411                         printk("slot %d offset bad key\n", i);
 412                         BUG_ON(1);
 413                 }
 414                 if (btrfs_item_offset_nr(leaf, i) !=
 415                         btrfs_item_end_nr(leaf, i + 1)) {
 416                         btrfs_print_leaf(root, leaf);
 417                         printk("slot %d offset bad\n", i);
 418                         BUG_ON(1);
 419                 }
 420                 if (i == 0) {
 421                         if (btrfs_item_offset_nr(leaf, i) +
 422                                btrfs_item_size_nr(leaf, i) !=
 423                                BTRFS_LEAF_DATA_SIZE(root)) {
 424                                 btrfs_print_leaf(root, leaf);
 425                                 printk("slot %d first offset bad\n", i);
 426                                 BUG_ON(1);
 427                         }
 428                 }
 429         }
 430         if (nritems > 0) {
 431                 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
 432                                 btrfs_print_leaf(root, leaf);
 433                                 printk("slot %d bad size \n", nritems - 1);
 434                                 BUG_ON(1);
 435                 }
 436         }
 437 #endif
 438         if (slot != 0 && slot < nritems - 1) {
 439                 btrfs_item_key(leaf, &leaf_key, slot);
 440                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 441                 if (comp_keys(&leaf_key, &cpukey) <= 0) {
 442                         btrfs_print_leaf(root, leaf);
 443                         printk("slot %d offset bad key\n", slot);
 444                         BUG_ON(1);
 445                 }
 446                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 447                        btrfs_item_end_nr(leaf, slot)) {
 448                         btrfs_print_leaf(root, leaf);
 449                         printk("slot %d offset bad\n", slot);
 450                         BUG_ON(1);
 451                 }
 452         }
 453         if (slot < nritems - 1) {
 454                 btrfs_item_key(leaf, &leaf_key, slot);
 455                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 456                 BUG_ON(comp_keys(&leaf_key, &cpukey) >= 0);
 457                 if (btrfs_item_offset_nr(leaf, slot) !=
 458                         btrfs_item_end_nr(leaf, slot + 1)) {
 459                         btrfs_print_leaf(root, leaf);
 460                         printk("slot %d offset bad\n", slot);
 461                         BUG_ON(1);
 462                 }
 463         }
 464         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 465                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 466         return 0;
 467 }
 468
 469 static int check_block(struct btrfs_root *root, struct btrfs_path *path,
 470                         int level)
 471 {
 472         return 0;
 473 #if 0
 474         struct extent_buffer *buf = path->nodes[level];
 475
 476         if (memcmp_extent_buffer(buf, root->fs_info->fsid,
 477                                  (unsigned long)btrfs_header_fsid(buf),
 478                                  BTRFS_FSID_SIZE)) {
 479                 printk("warning bad block %Lu\n", buf->start);
 480                 return 1;
 481         }
 482 #endif
 483         if (level == 0)
 484                 return check_leaf(root, path, level);
 485         return check_node(root, path, level);
 486 }
 487
 488 /*
 489  * search for key in the extent_buffer.  The items start at offset p,
 490  * and they are item_size apart.  There are 'max' items in p.
 491  *
 492  * the slot in the array is returned via slot, and it points to
 493  * the place where you would insert key if it is not found in
 494  * the array.
 495  *
 496  * slot may point to max if the key is bigger than all of the keys
 497  */
 498 static int generic_bin_search(struct extent_buffer *eb, unsigned long p,
 499                               int item_size, struct btrfs_key *key,
 500                               int max, int *slot)
 501 {
 502         int low = 0;
 503         int high = max;
 504         int mid;
 505         int ret;
 506         struct btrfs_disk_key *tmp = NULL;
 507         struct btrfs_disk_key unaligned;
 508         unsigned long offset;
 509         char *map_token = NULL;
 510         char *kaddr = NULL;
 511         unsigned long map_start = 0;
 512         unsigned long map_len = 0;
 513         int err;
 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_token = NULL;
 525                         }
 526                         err = map_extent_buffer(eb, offset,
 527                                                 sizeof(struct btrfs_disk_key),
 528                                                 &map_token, &kaddr,
 529                                                 &map_start, &map_len, KM_USER0);
 530
 531                         if (!err) {
 532                                 tmp = (struct btrfs_disk_key *)(kaddr + offset -
 533                                                         map_start);
 534                         } else {
 535                                 read_extent_buffer(eb, &unaligned,
 536                                                    offset, sizeof(unaligned));
 537                                 tmp = &unaligned;
 538                         }
 539
 540                 } else {
 541                         tmp = (struct btrfs_disk_key *)(kaddr + offset -
 542                                                         map_start);
 543                 }
 544                 ret = comp_keys(tmp, key);
 545
 546                 if (ret < 0)
 547                         low = mid + 1;
 548                 else if (ret > 0)
 549                         high = mid;
 550                 else {
 551                         *slot = mid;
 552                         if (map_token)
 553                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 554                         return 0;
 555                 }
 556         }
 557         *slot = low;
 558         if (map_token)
 559                 unmap_extent_buffer(eb, map_token, KM_USER0);
 560         return 1;
 561 }
 562
 563 /*
 564  * simple bin_search frontend that does the right thing for
 565  * leaves vs nodes
 566  */
 567 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 568                       int level, int *slot)
 569 {
 570         if (level == 0) {
 571                 return generic_bin_search(eb,
 572                                           offsetof(struct btrfs_leaf, items),
 573                                           sizeof(struct btrfs_item),
 574                                           key, btrfs_header_nritems(eb),
 575                                           slot);
 576         } else {
 577                 return generic_bin_search(eb,
 578                                           offsetof(struct btrfs_node, ptrs),
 579                                           sizeof(struct btrfs_key_ptr),
 580                                           key, btrfs_header_nritems(eb),
 581                                           slot);
 582         }
 583         return -1;
 584 }
 585
 586 static struct extent_buffer *read_node_slot(struct btrfs_root *root,
 587                                    struct extent_buffer *parent, int slot)
 588 {
 589         if (slot < 0)
 590                 return NULL;
 591         if (slot >= btrfs_header_nritems(parent))
 592                 return NULL;
 593         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 594                        btrfs_level_size(root, btrfs_header_level(parent) - 1));
 595 }
 596
 597 static int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root
 598                          *root, struct btrfs_path *path, int level)
 599 {
 600         struct extent_buffer *right = NULL;
 601         struct extent_buffer *mid;
 602         struct extent_buffer *left = NULL;
 603         struct extent_buffer *parent = NULL;
 604         int ret = 0;
 605         int wret;
 606         int pslot;
 607         int orig_slot = path->slots[level];
 608         int err_on_enospc = 0;
 609         u64 orig_ptr;
 610
 611         if (level == 0)
 612                 return 0;
 613
 614         mid = path->nodes[level];
 615         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 616
 617         if (level < BTRFS_MAX_LEVEL - 1)
 618                 parent = path->nodes[level + 1];
 619         pslot = path->slots[level + 1];
 620
 621         /*
 622          * deal with the case where there is only one pointer in the root
 623          * by promoting the node below to a root
 624          */
 625         if (!parent) {
 626                 struct extent_buffer *child;
 627
 628                 if (btrfs_header_nritems(mid) != 1)
 629                         return 0;
 630
 631                 /* promote the child to a root */
 632                 child = read_node_slot(root, mid, 0);
 633                 BUG_ON(!child);
 634                 root->node = child;
 635                 path->nodes[level] = NULL;
 636                 clean_tree_block(trans, root, mid);
 637                 wait_on_tree_block_writeback(root, mid);
 638                 /* once for the path */
 639                 free_extent_buffer(mid);
 640                 ret = btrfs_free_extent(trans, root, mid->start, mid->len, 1);
 641                 /* once for the root ptr */
 642                 free_extent_buffer(mid);
 643                 return ret;
 644         }
 645         if (btrfs_header_nritems(mid) >
 646             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 647                 return 0;
 648
 649         if (btrfs_header_nritems(mid) < 2)
 650                 err_on_enospc = 1;
 651
 652         left = read_node_slot(root, parent, pslot - 1);
 653         if (left) {
 654                 wret = btrfs_cow_block(trans, root, left,
 655                                        parent, pslot - 1, &left);
 656                 if (wret) {
 657                         ret = wret;
 658                         goto enospc;
 659                 }
 660         }
 661         right = read_node_slot(root, parent, pslot + 1);
 662         if (right) {
 663                 wret = btrfs_cow_block(trans, root, right,
 664                                        parent, pslot + 1, &right);
 665                 if (wret) {
 666                         ret = wret;
 667                         goto enospc;
 668                 }
 669         }
 670
 671         /* first, try to make some room in the middle buffer */
 672         if (left) {
 673                 orig_slot += btrfs_header_nritems(left);
 674                 wret = push_node_left(trans, root, left, mid);
 675                 if (wret < 0)
 676                         ret = wret;
 677                 if (btrfs_header_nritems(mid) < 2)
 678                         err_on_enospc = 1;
 679         }
 680
 681         /*
 682          * then try to empty the right most buffer into the middle
 683          */
 684         if (right) {
 685                 wret = push_node_left(trans, root, mid, right);
 686                 if (wret < 0 && wret != -ENOSPC)
 687                         ret = wret;
 688                 if (btrfs_header_nritems(right) == 0) {
 689                         u64 bytenr = right->start;
 690                         u32 blocksize = right->len;
 691
 692                         clean_tree_block(trans, root, right);
 693                         wait_on_tree_block_writeback(root, right);
 694                         free_extent_buffer(right);
 695                         right = NULL;
 696                         wret = del_ptr(trans, root, path, level + 1, pslot +
 697                                        1);
 698                         if (wret)
 699                                 ret = wret;
 700                         wret = btrfs_free_extent(trans, root, bytenr,
 701                                                  blocksize, 1);
 702                         if (wret)
 703                                 ret = wret;
 704                 } else {
 705                         struct btrfs_disk_key right_key;
 706                         btrfs_node_key(right, &right_key, 0);
 707                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 708                         btrfs_mark_buffer_dirty(parent);
 709                 }
 710         }
 711         if (btrfs_header_nritems(mid) == 1) {
 712                 /*
 713                  * we're not allowed to leave a node with one item in the
 714                  * tree during a delete.  A deletion from lower in the tree
 715                  * could try to delete the only pointer in this node.
 716                  * So, pull some keys from the left.
 717                  * There has to be a left pointer at this point because
 718                  * otherwise we would have pulled some pointers from the
 719                  * right
 720                  */
 721                 BUG_ON(!left);
 722                 wret = balance_node_right(trans, root, mid, left);
 723                 if (wret < 0) {
 724                         ret = wret;
 725                         goto enospc;
 726                 }
 727                 BUG_ON(wret == 1);
 728         }
 729         if (btrfs_header_nritems(mid) == 0) {
 730                 /* we've managed to empty the middle node, drop it */
 731                 u64 bytenr = mid->start;
 732                 u32 blocksize = mid->len;
 733                 clean_tree_block(trans, root, mid);
 734                 wait_on_tree_block_writeback(root, mid);
 735                 free_extent_buffer(mid);
 736                 mid = NULL;
 737                 wret = del_ptr(trans, root, path, level + 1, pslot);
 738                 if (wret)
 739                         ret = wret;
 740                 wret = btrfs_free_extent(trans, root, bytenr, blocksize, 1);
 741                 if (wret)
 742                         ret = wret;
 743         } else {
 744                 /* update the parent key to reflect our changes */
 745                 struct btrfs_disk_key mid_key;
 746                 btrfs_node_key(mid, &mid_key, 0);
 747                 btrfs_set_node_key(parent, &mid_key, pslot);
 748                 btrfs_mark_buffer_dirty(parent);
 749         }
 750
 751         /* update the path */
 752         if (left) {
 753                 if (btrfs_header_nritems(left) > orig_slot) {
 754                         extent_buffer_get(left);
 755                         path->nodes[level] = left;
 756                         path->slots[level + 1] -= 1;
 757                         path->slots[level] = orig_slot;
 758                         if (mid)
 759                                 free_extent_buffer(mid);
 760                 } else {
 761                         orig_slot -= btrfs_header_nritems(left);
 762                         path->slots[level] = orig_slot;
 763                 }
 764         }
 765         /* double check we haven't messed things up */
 766         check_block(root, path, level);
 767         if (orig_ptr !=
 768             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 769                 BUG();
 770 enospc:
 771         if (right)
 772                 free_extent_buffer(right);
 773         if (left)
 774                 free_extent_buffer(left);
 775         return ret;
 776 }
 777
 778 /* returns zero if the push worked, non-zero otherwise */
 779 static int push_nodes_for_insert(struct btrfs_trans_handle *trans,
 780                                 struct btrfs_root *root,
 781                                 struct btrfs_path *path, int level)
 782 {
 783         struct extent_buffer *right = NULL;
 784         struct extent_buffer *mid;
 785         struct extent_buffer *left = NULL;
 786         struct extent_buffer *parent = NULL;
 787         int ret = 0;
 788         int wret;
 789         int pslot;
 790         int orig_slot = path->slots[level];
 791         u64 orig_ptr;
 792
 793         if (level == 0)
 794                 return 1;
 795
 796         mid = path->nodes[level];
 797         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 798
 799         if (level < BTRFS_MAX_LEVEL - 1)
 800                 parent = path->nodes[level + 1];
 801         pslot = path->slots[level + 1];
 802
 803         if (!parent)
 804                 return 1;
 805
 806         left = read_node_slot(root, parent, pslot - 1);
 807
 808         /* first, try to make some room in the middle buffer */
 809         if (left) {
 810                 u32 left_nr;
 811                 left_nr = btrfs_header_nritems(left);
 812                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 813                         wret = 1;
 814                 } else {
 815                         ret = btrfs_cow_block(trans, root, left, parent,
 816                                               pslot - 1, &left);
 817                         if (ret)
 818                                 wret = 1;
 819                         else {
 820                                 wret = push_node_left(trans, root,
 821                                                       left, mid);
 822                         }
 823                 }
 824                 if (wret < 0)
 825                         ret = wret;
 826                 if (wret == 0) {
 827                         struct btrfs_disk_key disk_key;
 828                         orig_slot += left_nr;
 829                         btrfs_node_key(mid, &disk_key, 0);
 830                         btrfs_set_node_key(parent, &disk_key, pslot);
 831                         btrfs_mark_buffer_dirty(parent);
 832                         if (btrfs_header_nritems(left) > orig_slot) {
 833                                 path->nodes[level] = left;
 834                                 path->slots[level + 1] -= 1;
 835                                 path->slots[level] = orig_slot;
 836                                 free_extent_buffer(mid);
 837                         } else {
 838                                 orig_slot -=
 839                                         btrfs_header_nritems(left);
 840                                 path->slots[level] = orig_slot;
 841                                 free_extent_buffer(left);
 842                         }
 843                         return 0;
 844                 }
 845                 free_extent_buffer(left);
 846         }
 847         right= read_node_slot(root, parent, pslot + 1);
 848
 849         /*
 850          * then try to empty the right most buffer into the middle
 851          */
 852         if (right) {
 853                 u32 right_nr;
 854                 right_nr = btrfs_header_nritems(right);
 855                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 856                         wret = 1;
 857                 } else {
 858                         ret = btrfs_cow_block(trans, root, right,
 859                                               parent, pslot + 1,
 860                                               &right);
 861                         if (ret)
 862                                 wret = 1;
 863                         else {
 864                                 wret = balance_node_right(trans, root,
 865                                                           right, mid);
 866                         }
 867                 }
 868                 if (wret < 0)
 869                         ret = wret;
 870                 if (wret == 0) {
 871                         struct btrfs_disk_key disk_key;
 872
 873                         btrfs_node_key(right, &disk_key, 0);
 874                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
 875                         btrfs_mark_buffer_dirty(parent);
 876
 877                         if (btrfs_header_nritems(mid) <= orig_slot) {
 878                                 path->nodes[level] = right;
 879                                 path->slots[level + 1] += 1;
 880                                 path->slots[level] = orig_slot -
 881                                         btrfs_header_nritems(mid);
 882                                 free_extent_buffer(mid);
 883                         } else {
 884                                 free_extent_buffer(right);
 885                         }
 886                         return 0;
 887                 }
 888                 free_extent_buffer(right);
 889         }
 890         return 1;
 891 }
 892
 893 /*
 894  * readahead one full node of leaves
 895  */
 896 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 897                              int level, int slot)
 898 {
 899         struct extent_buffer *node;
 900         u32 nritems;
 901         u64 search;
 902         u64 lowest_read;
 903         u64 highest_read;
 904         u64 nread = 0;
 905         int direction = path->reada;
 906         struct extent_buffer *eb;
 907         u32 nr;
 908         u32 blocksize;
 909         u32 nscan = 0;
 910
 911         if (level != 1)
 912                 return;
 913
 914         if (!path->nodes[level])
 915                 return;
 916
 917         node = path->nodes[level];
 918         search = btrfs_node_blockptr(node, slot);
 919         blocksize = btrfs_level_size(root, level - 1);
 920         eb = btrfs_find_tree_block(root, search, blocksize);
 921         if (eb) {
 922                 free_extent_buffer(eb);
 923                 return;
 924         }
 925
 926         highest_read = search;
 927         lowest_read = search;
 928
 929         nritems = btrfs_header_nritems(node);
 930         nr = slot;
 931         while(1) {
 932                 if (direction < 0) {
 933                         if (nr == 0)
 934                                 break;
 935                         nr--;
 936                 } else if (direction > 0) {
 937                         nr++;
 938                         if (nr >= nritems)
 939                                 break;
 940                 }
 941                 search = btrfs_node_blockptr(node, nr);
 942                 if ((search >= lowest_read && search <= highest_read) ||
 943                     (search < lowest_read && lowest_read - search <= 32768) ||
 944                     (search > highest_read && search - highest_read <= 32768)) {
 945                         readahead_tree_block(root, search, blocksize);
 946                         nread += blocksize;
 947                 }
 948                 nscan++;
 949                 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
 950                         break;
 951                 if(nread > (1024 * 1024) || nscan > 128)
 952                         break;
 953
 954                 if (search < lowest_read)
 955                         lowest_read = search;
 956                 if (search > highest_read)
 957                         highest_read = search;
 958         }
 959 }
 960 /*
 961  * look for key in the tree.  path is filled in with nodes along the way
 962  * if key is found, we return zero and you can find the item in the leaf
 963  * level of the path (level 0)
 964  *
 965  * If the key isn't found, the path points to the slot where it should
 966  * be inserted, and 1 is returned.  If there are other errors during the
 967  * search a negative error number is returned.
 968  *
 969  * if ins_len > 0, nodes and leaves will be split as we walk down the
 970  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
 971  * possible)
 972  */
 973 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 974                       *root, struct btrfs_key *key, struct btrfs_path *p, int
 975                       ins_len, int cow)
 976 {
 977         struct extent_buffer *b;
 978         u64 bytenr;
 979         int slot;
 980         int ret;
 981         int level;
 982         int should_reada = p->reada;
 983         u8 lowest_level = 0;
 984
 985         lowest_level = p->lowest_level;
 986         WARN_ON(lowest_level && ins_len);
 987         WARN_ON(p->nodes[0] != NULL);
 988         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
 989 again:
 990         b = root->node;
 991         extent_buffer_get(b);
 992         while (b) {
 993                 level = btrfs_header_level(b);
 994                 if (cow) {
 995                         int wret;
 996                         wret = btrfs_cow_block(trans, root, b,
 997                                                p->nodes[level + 1],
 998                                                p->slots[level + 1],
 999                                                &b);
1000                         if (wret) {
1001                                 free_extent_buffer(b);
1002                                 return wret;
1003                         }
1004                 }
1005                 BUG_ON(!cow && ins_len);
1006                 if (level != btrfs_header_level(b))
1007                         WARN_ON(1);
1008                 level = btrfs_header_level(b);
1009                 p->nodes[level] = b;
1010                 ret = check_block(root, p, level);
1011                 if (ret)
1012                         return -1;
1013                 ret = bin_search(b, key, level, &slot);
1014                 if (level != 0) {
1015                         if (ret && slot > 0)
1016                                 slot -= 1;
1017                         p->slots[level] = slot;
1018                         if (ins_len > 0 && btrfs_header_nritems(b) >=
1019                             BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1020                                 int sret = split_node(trans, root, p, level);
1021                                 BUG_ON(sret > 0);
1022                                 if (sret)
1023                                         return sret;
1024                                 b = p->nodes[level];
1025                                 slot = p->slots[level];
1026                         } else if (ins_len < 0) {
1027                                 int sret = balance_level(trans, root, p,
1028                                                          level);
1029                                 if (sret)
1030                                         return sret;
1031                                 b = p->nodes[level];
1032                                 if (!b) {
1033                                         btrfs_release_path(NULL, p);
1034                                         goto again;
1035                                 }
1036                                 slot = p->slots[level];
1037                                 BUG_ON(btrfs_header_nritems(b) == 1);
1038                         }
1039                         /* this is only true while dropping a snapshot */
1040                         if (level == lowest_level)
1041                                 break;
1042                         bytenr = btrfs_node_blockptr(b, slot);
1043                         if (should_reada)
1044                                 reada_for_search(root, p, level, slot);
1045                         b = read_tree_block(root, bytenr,
1046                                             btrfs_level_size(root, level - 1));
1047                 } else {
1048                         p->slots[level] = slot;
1049                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1050                             sizeof(struct btrfs_item) + ins_len) {
1051                                 int sret = split_leaf(trans, root, key,
1052                                                       p, ins_len);
1053                                 BUG_ON(sret > 0);
1054                                 if (sret)
1055                                         return sret;
1056                         }
1057                         return ret;
1058                 }
1059         }
1060         return 1;
1061 }
1062
1063 /*
1064  * adjust the pointers going up the tree, starting at level
1065  * making sure the right key of each node is points to 'key'.
1066  * This is used after shifting pointers to the left, so it stops
1067  * fixing up pointers when a given leaf/node is not in slot 0 of the
1068  * higher levels
1069  *
1070  * If this fails to write a tree block, it returns -1, but continues
1071  * fixing up the blocks in ram so the tree is consistent.
1072  */
1073 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1074                           struct btrfs_root *root, struct btrfs_path *path,
1075                           struct btrfs_disk_key *key, int level)
1076 {
1077         int i;
1078         int ret = 0;
1079         struct extent_buffer *t;
1080
1081         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1082                 int tslot = path->slots[i];
1083                 if (!path->nodes[i])
1084                         break;
1085                 t = path->nodes[i];
1086                 btrfs_set_node_key(t, key, tslot);
1087                 btrfs_mark_buffer_dirty(path->nodes[i]);
1088                 if (tslot != 0)
1089                         break;
1090         }
1091         return ret;
1092 }
1093
1094 /*
1095  * try to push data from one node into the next node left in the
1096  * tree.
1097  *
1098  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1099  * error, and > 0 if there was no room in the left hand block.
1100  */
1101 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
1102                           *root, struct extent_buffer *dst,
1103                           struct extent_buffer *src)
1104 {
1105         int push_items = 0;
1106         int src_nritems;
1107         int dst_nritems;
1108         int ret = 0;
1109
1110         src_nritems = btrfs_header_nritems(src);
1111         dst_nritems = btrfs_header_nritems(dst);
1112         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1113
1114         if (push_items <= 0) {
1115                 return 1;
1116         }
1117
1118         if (src_nritems < push_items)
1119                 push_items = src_nritems;
1120
1121         copy_extent_buffer(dst, src,
1122                            btrfs_node_key_ptr_offset(dst_nritems),
1123                            btrfs_node_key_ptr_offset(0),
1124                            push_items * sizeof(struct btrfs_key_ptr));
1125
1126         if (push_items < src_nritems) {
1127                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1128                                       btrfs_node_key_ptr_offset(push_items),
1129                                       (src_nritems - push_items) *
1130                                       sizeof(struct btrfs_key_ptr));
1131         }
1132         btrfs_set_header_nritems(src, src_nritems - push_items);
1133         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1134         btrfs_mark_buffer_dirty(src);
1135         btrfs_mark_buffer_dirty(dst);
1136         return ret;
1137 }
1138
1139 /*
1140  * try to push data from one node into the next node right in the
1141  * tree.
1142  *
1143  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1144  * error, and > 0 if there was no room in the right hand block.
1145  *
1146  * this will  only push up to 1/2 the contents of the left node over
1147  */
1148 static int balance_node_right(struct btrfs_trans_handle *trans,
1149                               struct btrfs_root *root,
1150                               struct extent_buffer *dst,
1151                               struct extent_buffer *src)
1152 {
1153         int push_items = 0;
1154         int max_push;
1155         int src_nritems;
1156         int dst_nritems;
1157         int ret = 0;
1158
1159         src_nritems = btrfs_header_nritems(src);
1160         dst_nritems = btrfs_header_nritems(dst);
1161         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1162         if (push_items <= 0)
1163                 return 1;
1164
1165         max_push = src_nritems / 2 + 1;
1166         /* don't try to empty the node */
1167         if (max_push >= src_nritems)
1168                 return 1;
1169
1170         if (max_push < push_items)
1171                 push_items = max_push;
1172
1173         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1174                                       btrfs_node_key_ptr_offset(0),
1175                                       (dst_nritems) *
1176                                       sizeof(struct btrfs_key_ptr));
1177
1178         copy_extent_buffer(dst, src,
1179                            btrfs_node_key_ptr_offset(0),
1180                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1181                            push_items * sizeof(struct btrfs_key_ptr));
1182
1183         btrfs_set_header_nritems(src, src_nritems - push_items);
1184         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1185
1186         btrfs_mark_buffer_dirty(src);
1187         btrfs_mark_buffer_dirty(dst);
1188         return ret;
1189 }
1190
1191 /*
1192  * helper function to insert a new root level in the tree.
1193  * A new node is allocated, and a single item is inserted to
1194  * point to the existing root
1195  *
1196  * returns zero on success or < 0 on failure.
1197  */
1198 static int insert_new_root(struct btrfs_trans_handle *trans,
1199                            struct btrfs_root *root,
1200                            struct btrfs_path *path, int level)
1201 {
1202         struct extent_buffer *lower;
1203         struct extent_buffer *c;
1204         struct btrfs_disk_key lower_key;
1205
1206         BUG_ON(path->nodes[level]);
1207         BUG_ON(path->nodes[level-1] != root->node);
1208
1209         c = btrfs_alloc_free_block(trans, root, root->nodesize,
1210                                    root->node->start, 0);
1211         if (IS_ERR(c))
1212                 return PTR_ERR(c);
1213         memset_extent_buffer(c, 0, 0, root->nodesize);
1214         btrfs_set_header_nritems(c, 1);
1215         btrfs_set_header_level(c, level);
1216         btrfs_set_header_bytenr(c, c->start);
1217         btrfs_set_header_generation(c, trans->transid);
1218         btrfs_set_header_owner(c, root->root_key.objectid);
1219         lower = path->nodes[level-1];
1220
1221         write_extent_buffer(c, root->fs_info->fsid,
1222                             (unsigned long)btrfs_header_fsid(c),
1223                             BTRFS_FSID_SIZE);
1224         if (level == 1)
1225                 btrfs_item_key(lower, &lower_key, 0);
1226         else
1227                 btrfs_node_key(lower, &lower_key, 0);
1228         btrfs_set_node_key(c, &lower_key, 0);
1229         btrfs_set_node_blockptr(c, 0, lower->start);
1230
1231         btrfs_mark_buffer_dirty(c);
1232
1233         /* the super has an extra ref to root->node */
1234         free_extent_buffer(root->node);
1235         root->node = c;
1236         extent_buffer_get(c);
1237         path->nodes[level] = c;
1238         path->slots[level] = 0;
1239         return 0;
1240 }
1241
1242 /*
1243  * worker function to insert a single pointer in a node.
1244  * the node should have enough room for the pointer already
1245  *
1246  * slot and level indicate where you want the key to go, and
1247  * blocknr is the block the key points to.
1248  *
1249  * returns zero on success and < 0 on any error
1250  */
1251 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1252                       *root, struct btrfs_path *path, struct btrfs_disk_key
1253                       *key, u64 bytenr, int slot, int level)
1254 {
1255         struct extent_buffer *lower;
1256         int nritems;
1257
1258         BUG_ON(!path->nodes[level]);
1259         lower = path->nodes[level];
1260         nritems = btrfs_header_nritems(lower);
1261         if (slot > nritems)
1262                 BUG();
1263         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1264                 BUG();
1265         if (slot != nritems) {
1266                 memmove_extent_buffer(lower,
1267                               btrfs_node_key_ptr_offset(slot + 1),
1268                               btrfs_node_key_ptr_offset(slot),
1269                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1270         }
1271         btrfs_set_node_key(lower, key, slot);
1272         btrfs_set_node_blockptr(lower, slot, bytenr);
1273         btrfs_set_header_nritems(lower, nritems + 1);
1274         btrfs_mark_buffer_dirty(lower);
1275         return 0;
1276 }
1277
1278 /*
1279  * split the node at the specified level in path in two.
1280  * The path is corrected to point to the appropriate node after the split
1281  *
1282  * Before splitting this tries to make some room in the node by pushing
1283  * left and right, if either one works, it returns right away.
1284  *
1285  * returns 0 on success and < 0 on failure
1286  */
1287 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1288                       *root, struct btrfs_path *path, int level)
1289 {
1290         struct extent_buffer *c;
1291         struct extent_buffer *split;
1292         struct btrfs_disk_key disk_key;
1293         int mid;
1294         int ret;
1295         int wret;
1296         u32 c_nritems;
1297
1298         c = path->nodes[level];
1299         if (c == root->node) {
1300                 /* trying to split the root, lets make a new one */
1301                 ret = insert_new_root(trans, root, path, level + 1);
1302                 if (ret)
1303                         return ret;
1304         } else {
1305                 ret = push_nodes_for_insert(trans, root, path, level);
1306                 c = path->nodes[level];
1307                 if (!ret && btrfs_header_nritems(c) <
1308                     BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
1309                         return 0;
1310                 if (ret < 0)
1311                         return ret;
1312         }
1313
1314         c_nritems = btrfs_header_nritems(c);
1315         split = btrfs_alloc_free_block(trans, root, root->nodesize,
1316                                        c->start, 0);
1317         if (IS_ERR(split))
1318                 return PTR_ERR(split);
1319
1320         btrfs_set_header_flags(split, btrfs_header_flags(c));
1321         btrfs_set_header_level(split, btrfs_header_level(c));
1322         btrfs_set_header_bytenr(split, split->start);
1323         btrfs_set_header_generation(split, trans->transid);
1324         btrfs_set_header_owner(split, root->root_key.objectid);
1325         write_extent_buffer(split, root->fs_info->fsid,
1326                             (unsigned long)btrfs_header_fsid(split),
1327                             BTRFS_FSID_SIZE);
1328
1329         mid = (c_nritems + 1) / 2;
1330
1331         copy_extent_buffer(split, c,
1332                            btrfs_node_key_ptr_offset(0),
1333                            btrfs_node_key_ptr_offset(mid),
1334                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1335         btrfs_set_header_nritems(split, c_nritems - mid);
1336         btrfs_set_header_nritems(c, mid);
1337         ret = 0;
1338
1339         btrfs_mark_buffer_dirty(c);
1340         btrfs_mark_buffer_dirty(split);
1341
1342         btrfs_node_key(split, &disk_key, 0);
1343         wret = insert_ptr(trans, root, path, &disk_key, split->start,
1344                           path->slots[level + 1] + 1,
1345                           level + 1);
1346         if (wret)
1347                 ret = wret;
1348
1349         if (path->slots[level] >= mid) {
1350                 path->slots[level] -= mid;
1351                 free_extent_buffer(c);
1352                 path->nodes[level] = split;
1353                 path->slots[level + 1] += 1;
1354         } else {
1355                 free_extent_buffer(split);
1356         }
1357         return ret;
1358 }
1359
1360 /*
1361  * how many bytes are required to store the items in a leaf.  start
1362  * and nr indicate which items in the leaf to check.  This totals up the
1363  * space used both by the item structs and the item data
1364  */
1365 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1366 {
1367         int data_len;
1368         int nritems = btrfs_header_nritems(l);
1369         int end = min(nritems, start + nr) - 1;
1370
1371         if (!nr)
1372                 return 0;
1373         data_len = btrfs_item_end_nr(l, start);
1374         data_len = data_len - btrfs_item_offset_nr(l, end);
1375         data_len += sizeof(struct btrfs_item) * nr;
1376         WARN_ON(data_len < 0);
1377         return data_len;
1378 }
1379
1380 /*
1381  * The space between the end of the leaf items and
1382  * the start of the leaf data.  IOW, how much room
1383  * the leaf has left for both items and data
1384  */
1385 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1386 {
1387         int nritems = btrfs_header_nritems(leaf);
1388         int ret;
1389         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1390         if (ret < 0) {
1391                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1392                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
1393                        leaf_space_used(leaf, 0, nritems), nritems);
1394         }
1395         return ret;
1396 }
1397
1398 /*
1399  * push some data in the path leaf to the right, trying to free up at
1400  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1401  *
1402  * returns 1 if the push failed because the other node didn't have enough
1403  * room, 0 if everything worked out and < 0 if there were major errors.
1404  */
1405 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1406                            *root, struct btrfs_path *path, int data_size)
1407 {
1408         struct extent_buffer *left = path->nodes[0];
1409         struct extent_buffer *right;
1410         struct extent_buffer *upper;
1411         struct btrfs_disk_key disk_key;
1412         int slot;
1413         int i;
1414         int free_space;
1415         int push_space = 0;
1416         int push_items = 0;
1417         struct btrfs_item *item;
1418         u32 left_nritems;
1419         u32 right_nritems;
1420         u32 data_end;
1421         u32 this_item_size;
1422         int ret;
1423
1424         slot = path->slots[1];
1425         if (!path->nodes[1]) {
1426                 return 1;
1427         }
1428         upper = path->nodes[1];
1429         if (slot >= btrfs_header_nritems(upper) - 1)
1430                 return 1;
1431
1432         right = read_tree_block(root, btrfs_node_blockptr(upper, slot + 1),
1433                                 root->leafsize);
1434         free_space = btrfs_leaf_free_space(root, right);
1435         if (free_space < data_size + sizeof(struct btrfs_item)) {
1436                 free_extent_buffer(right);
1437                 return 1;
1438         }
1439
1440         /* cow and double check */
1441         ret = btrfs_cow_block(trans, root, right, upper,
1442                               slot + 1, &right);
1443         if (ret) {
1444                 free_extent_buffer(right);
1445                 return 1;
1446         }
1447         free_space = btrfs_leaf_free_space(root, right);
1448         if (free_space < data_size + sizeof(struct btrfs_item)) {
1449                 free_extent_buffer(right);
1450                 return 1;
1451         }
1452
1453         left_nritems = btrfs_header_nritems(left);
1454         if (left_nritems == 0) {
1455                 free_extent_buffer(right);
1456                 return 1;
1457         }
1458
1459         for (i = left_nritems - 1; i >= 1; i--) {
1460                 item = btrfs_item_nr(left, i);
1461
1462                 if (path->slots[0] == i)
1463                         push_space += data_size + sizeof(*item);
1464
1465                 if (!left->map_token) {
1466                         map_extent_buffer(left, (unsigned long)item,
1467                                         sizeof(struct btrfs_item),
1468                                         &left->map_token, &left->kaddr,
1469                                         &left->map_start, &left->map_len,
1470                                         KM_USER1);
1471                 }
1472
1473                 this_item_size = btrfs_item_size(left, item);
1474                 if (this_item_size + sizeof(*item) + push_space > free_space)
1475                         break;
1476                 push_items++;
1477                 push_space += this_item_size + sizeof(*item);
1478         }
1479         if (left->map_token) {
1480                 unmap_extent_buffer(left, left->map_token, KM_USER1);
1481                 left->map_token = NULL;
1482         }
1483
1484         if (push_items == 0) {
1485                 free_extent_buffer(right);
1486                 return 1;
1487         }
1488
1489         if (push_items == left_nritems)
1490                 WARN_ON(1);
1491
1492         /* push left to right */
1493         right_nritems = btrfs_header_nritems(right);
1494         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1495         push_space -= leaf_data_end(root, left);
1496
1497         /* make room in the right data area */
1498         data_end = leaf_data_end(root, right);
1499         memmove_extent_buffer(right,
1500                               btrfs_leaf_data(right) + data_end - push_space,
1501                               btrfs_leaf_data(right) + data_end,
1502                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1503
1504         /* copy from the left data area */
1505         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1506                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1507                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1508                      push_space);
1509
1510         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1511                               btrfs_item_nr_offset(0),
1512                               right_nritems * sizeof(struct btrfs_item));
1513
1514         /* copy the items from left to right */
1515         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1516                    btrfs_item_nr_offset(left_nritems - push_items),
1517                    push_items * sizeof(struct btrfs_item));
1518
1519         /* update the item pointers */
1520         right_nritems += push_items;
1521         btrfs_set_header_nritems(right, right_nritems);
1522         push_space = BTRFS_LEAF_DATA_SIZE(root);
1523
1524         for (i = 0; i < right_nritems; i++) {
1525                 item = btrfs_item_nr(right, i);
1526                 if (!right->map_token) {
1527                         map_extent_buffer(right, (unsigned long)item,
1528                                         sizeof(struct btrfs_item),
1529                                         &right->map_token, &right->kaddr,
1530                                         &right->map_start, &right->map_len,
1531                                         KM_USER1);
1532                 }
1533                 push_space -= btrfs_item_size(right, item);
1534                 btrfs_set_item_offset(right, item, push_space);
1535         }
1536
1537         if (right->map_token) {
1538                 unmap_extent_buffer(right, right->map_token, KM_USER1);
1539                 right->map_token = NULL;
1540         }
1541         left_nritems -= push_items;
1542         btrfs_set_header_nritems(left, left_nritems);
1543
1544         btrfs_mark_buffer_dirty(left);
1545         btrfs_mark_buffer_dirty(right);
1546
1547         btrfs_item_key(right, &disk_key, 0);
1548         btrfs_set_node_key(upper, &disk_key, slot + 1);
1549         btrfs_mark_buffer_dirty(upper);
1550
1551         /* then fixup the leaf pointer in the path */
1552         if (path->slots[0] >= left_nritems) {
1553                 path->slots[0] -= left_nritems;
1554                 free_extent_buffer(path->nodes[0]);
1555                 path->nodes[0] = right;
1556                 path->slots[1] += 1;
1557         } else {
1558                 free_extent_buffer(right);
1559         }
1560         return 0;
1561 }
1562 /*
1563  * push some data in the path leaf to the left, trying to free up at
1564  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1565  */
1566 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1567                           *root, struct btrfs_path *path, int data_size)
1568 {
1569         struct btrfs_disk_key disk_key;
1570         struct extent_buffer *right = path->nodes[0];
1571         struct extent_buffer *left;
1572         int slot;
1573         int i;
1574         int free_space;
1575         int push_space = 0;
1576         int push_items = 0;
1577         struct btrfs_item *item;
1578         u32 old_left_nritems;
1579         u32 right_nritems;
1580         int ret = 0;
1581         int wret;
1582         u32 this_item_size;
1583         u32 old_left_item_size;
1584
1585         slot = path->slots[1];
1586         if (slot == 0)
1587                 return 1;
1588         if (!path->nodes[1])
1589                 return 1;
1590
1591         right_nritems = btrfs_header_nritems(right);
1592         if (right_nritems == 0) {
1593                 return 1;
1594         }
1595
1596         left = read_tree_block(root, btrfs_node_blockptr(path->nodes[1],
1597                                slot - 1), root->leafsize);
1598         free_space = btrfs_leaf_free_space(root, left);
1599         if (free_space < data_size + sizeof(struct btrfs_item)) {
1600                 free_extent_buffer(left);
1601                 return 1;
1602         }
1603
1604         /* cow and double check */
1605         ret = btrfs_cow_block(trans, root, left,
1606                               path->nodes[1], slot - 1, &left);
1607         if (ret) {
1608                 /* we hit -ENOSPC, but it isn't fatal here */
1609                 free_extent_buffer(left);
1610                 return 1;
1611         }
1612
1613         free_space = btrfs_leaf_free_space(root, left);
1614         if (free_space < data_size + sizeof(struct btrfs_item)) {
1615                 free_extent_buffer(left);
1616                 return 1;
1617         }
1618
1619         for (i = 0; i < right_nritems - 1; i++) {
1620                 item = btrfs_item_nr(right, i);
1621                 if (!right->map_token) {
1622                         map_extent_buffer(right, (unsigned long)item,
1623                                         sizeof(struct btrfs_item),
1624                                         &right->map_token, &right->kaddr,
1625                                         &right->map_start, &right->map_len,
1626                                         KM_USER1);
1627                 }
1628
1629                 if (path->slots[0] == i)
1630                         push_space += data_size + sizeof(*item);
1631
1632                 this_item_size = btrfs_item_size(right, item);
1633                 if (this_item_size + sizeof(*item) + push_space > free_space)
1634                         break;
1635
1636                 push_items++;
1637                 push_space += this_item_size + sizeof(*item);
1638         }
1639
1640         if (right->map_token) {
1641                 unmap_extent_buffer(right, right->map_token, KM_USER1);
1642                 right->map_token = NULL;
1643         }
1644
1645         if (push_items == 0) {
1646                 free_extent_buffer(left);
1647                 return 1;
1648         }
1649         if (push_items == btrfs_header_nritems(right))
1650                 WARN_ON(1);
1651
1652         /* push data from right to left */
1653         copy_extent_buffer(left, right,
1654                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1655                            btrfs_item_nr_offset(0),
1656                            push_items * sizeof(struct btrfs_item));
1657
1658         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1659                      btrfs_item_offset_nr(right, push_items -1);
1660
1661         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1662                      leaf_data_end(root, left) - push_space,
1663                      btrfs_leaf_data(right) +
1664                      btrfs_item_offset_nr(right, push_items - 1),
1665                      push_space);
1666         old_left_nritems = btrfs_header_nritems(left);
1667         BUG_ON(old_left_nritems < 0);
1668
1669         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
1670         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1671                 u32 ioff;
1672
1673                 item = btrfs_item_nr(left, i);
1674                 if (!left->map_token) {
1675                         map_extent_buffer(left, (unsigned long)item,
1676                                         sizeof(struct btrfs_item),
1677                                         &left->map_token, &left->kaddr,
1678                                         &left->map_start, &left->map_len,
1679                                         KM_USER1);
1680                 }
1681
1682                 ioff = btrfs_item_offset(left, item);
1683                 btrfs_set_item_offset(left, item,
1684                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
1685         }
1686         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1687         if (left->map_token) {
1688                 unmap_extent_buffer(left, left->map_token, KM_USER1);
1689                 left->map_token = NULL;
1690         }
1691
1692         /* fixup right node */
1693         push_space = btrfs_item_offset_nr(right, push_items - 1) -
1694                                           leaf_data_end(root, right);
1695         memmove_extent_buffer(right, btrfs_leaf_data(right) +
1696                               BTRFS_LEAF_DATA_SIZE(root) - push_space,
1697                               btrfs_leaf_data(right) +
1698                               leaf_data_end(root, right), push_space);
1699
1700         memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1701                               btrfs_item_nr_offset(push_items),
1702                              (btrfs_header_nritems(right) - push_items) *
1703                              sizeof(struct btrfs_item));
1704
1705         right_nritems = btrfs_header_nritems(right) - push_items;
1706         btrfs_set_header_nritems(right, right_nritems);
1707         push_space = BTRFS_LEAF_DATA_SIZE(root);
1708
1709         for (i = 0; i < right_nritems; i++) {
1710                 item = btrfs_item_nr(right, i);
1711
1712                 if (!right->map_token) {
1713                         map_extent_buffer(right, (unsigned long)item,
1714                                         sizeof(struct btrfs_item),
1715                                         &right->map_token, &right->kaddr,
1716                                         &right->map_start, &right->map_len,
1717                                         KM_USER1);
1718                 }
1719
1720                 push_space = push_space - btrfs_item_size(right, item);
1721                 btrfs_set_item_offset(right, item, push_space);
1722         }
1723         if (right->map_token) {
1724                 unmap_extent_buffer(right, right->map_token, KM_USER1);
1725                 right->map_token = NULL;
1726         }
1727
1728         btrfs_mark_buffer_dirty(left);
1729         btrfs_mark_buffer_dirty(right);
1730
1731         btrfs_item_key(right, &disk_key, 0);
1732         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1733         if (wret)
1734                 ret = wret;
1735
1736         /* then fixup the leaf pointer in the path */
1737         if (path->slots[0] < push_items) {
1738                 path->slots[0] += old_left_nritems;
1739                 free_extent_buffer(path->nodes[0]);
1740                 path->nodes[0] = left;
1741                 path->slots[1] -= 1;
1742         } else {
1743                 free_extent_buffer(left);
1744                 path->slots[0] -= push_items;
1745         }
1746         BUG_ON(path->slots[0] < 0);
1747         return ret;
1748 }
1749
1750 /*
1751  * split the path's leaf in two, making sure there is at least data_size
1752  * available for the resulting leaf level of the path.
1753  *
1754  * returns 0 if all went well and < 0 on failure.
1755  */
1756 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1757                       *root, struct btrfs_key *ins_key,
1758                       struct btrfs_path *path, int data_size)
1759 {
1760         struct extent_buffer *l;
1761         u32 nritems;
1762         int mid;
1763         int slot;
1764         struct extent_buffer *right;
1765         int space_needed = data_size + sizeof(struct btrfs_item);
1766         int data_copy_size;
1767         int rt_data_off;
1768         int i;
1769         int ret = 0;
1770         int wret;
1771         int double_split = 0;
1772         struct btrfs_disk_key disk_key;
1773
1774         /* first try to make some room by pushing left and right */
1775         if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
1776                 wret = push_leaf_right(trans, root, path, data_size);
1777                 if (wret < 0) {
1778                         return wret;
1779                 }
1780                 if (wret) {
1781                         wret = push_leaf_left(trans, root, path, data_size);
1782                         if (wret < 0)
1783                                 return wret;
1784                 }
1785                 l = path->nodes[0];
1786
1787                 /* did the pushes work? */
1788                 if (btrfs_leaf_free_space(root, l) >=
1789                     sizeof(struct btrfs_item) + data_size) {
1790                         return 0;
1791                 }
1792         } else {
1793                 l = path->nodes[0];
1794         }
1795
1796         if (!path->nodes[1]) {
1797                 ret = insert_new_root(trans, root, path, 1);
1798                 if (ret)
1799                         return ret;
1800         }
1801         slot = path->slots[0];
1802         nritems = btrfs_header_nritems(l);
1803         mid = (nritems + 1)/ 2;
1804
1805         right = btrfs_alloc_free_block(trans, root, root->leafsize,
1806                                        l->start, 0);
1807         if (IS_ERR(right))
1808                 return PTR_ERR(right);
1809
1810         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1811         btrfs_set_header_bytenr(right, right->start);
1812         btrfs_set_header_generation(right, trans->transid);
1813         btrfs_set_header_owner(right, root->root_key.objectid);
1814         btrfs_set_header_level(right, 0);
1815         write_extent_buffer(right, root->fs_info->fsid,
1816                             (unsigned long)btrfs_header_fsid(right),
1817                             BTRFS_FSID_SIZE);
1818
1819         if (mid <= slot) {
1820                 if (nritems == 1 ||
1821                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1822                         BTRFS_LEAF_DATA_SIZE(root)) {
1823                         if (slot >= nritems) {
1824                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1825                                 btrfs_set_header_nritems(right, 0);
1826                                 wret = insert_ptr(trans, root, path,
1827                                                   &disk_key, right->start,
1828                                                   path->slots[1] + 1, 1);
1829                                 if (wret)
1830                                         ret = wret;
1831                                 free_extent_buffer(path->nodes[0]);
1832                                 path->nodes[0] = right;
1833                                 path->slots[0] = 0;
1834                                 path->slots[1] += 1;
1835                                 return ret;
1836                         }
1837                         mid = slot;
1838                         if (mid != nritems &&
1839                             leaf_space_used(l, mid, nritems - mid) +
1840                             space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1841                                 double_split = 1;
1842                         }
1843                 }
1844         } else {
1845                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1846                         BTRFS_LEAF_DATA_SIZE(root)) {
1847                         if (slot == 0) {
1848                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1849                                 btrfs_set_header_nritems(right, 0);
1850                                 wret = insert_ptr(trans, root, path,
1851                                                   &disk_key,
1852                                                   right->start,
1853                                                   path->slots[1], 1);
1854                                 if (wret)
1855                                         ret = wret;
1856                                 free_extent_buffer(path->nodes[0]);
1857                                 path->nodes[0] = right;
1858                                 path->slots[0] = 0;
1859                                 if (path->slots[1] == 0) {
1860                                         wret = fixup_low_keys(trans, root,
1861                                                    path, &disk_key, 1);
1862                                         if (wret)
1863                                                 ret = wret;
1864                                 }
1865                                 return ret;
1866                         }
1867                         mid = slot;
1868                         if (mid != nritems &&
1869                             leaf_space_used(l, mid, nritems - mid) +
1870                             space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1871                                 double_split = 1;
1872                         }
1873                 }
1874         }
1875         nritems = nritems - mid;
1876         btrfs_set_header_nritems(right, nritems);
1877         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
1878
1879         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
1880                            btrfs_item_nr_offset(mid),
1881                            nritems * sizeof(struct btrfs_item));
1882
1883         copy_extent_buffer(right, l,
1884                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1885                      data_copy_size, btrfs_leaf_data(l) +
1886                      leaf_data_end(root, l), data_copy_size);
1887
1888         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1889                       btrfs_item_end_nr(l, mid);
1890
1891         for (i = 0; i < nritems; i++) {
1892                 struct btrfs_item *item = btrfs_item_nr(right, i);
1893                 u32 ioff;
1894
1895                 if (!right->map_token) {
1896                         map_extent_buffer(right, (unsigned long)item,
1897                                         sizeof(struct btrfs_item),
1898                                         &right->map_token, &right->kaddr,
1899                                         &right->map_start, &right->map_len,
1900                                         KM_USER1);
1901                 }
1902
1903                 ioff = btrfs_item_offset(right, item);
1904                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
1905         }
1906
1907         if (right->map_token) {
1908                 unmap_extent_buffer(right, right->map_token, KM_USER1);
1909                 right->map_token = NULL;
1910         }
1911
1912         btrfs_set_header_nritems(l, mid);
1913         ret = 0;
1914         btrfs_item_key(right, &disk_key, 0);
1915         wret = insert_ptr(trans, root, path, &disk_key, right->start,
1916                           path->slots[1] + 1, 1);
1917         if (wret)
1918                 ret = wret;
1919
1920         btrfs_mark_buffer_dirty(right);
1921         btrfs_mark_buffer_dirty(l);
1922         BUG_ON(path->slots[0] != slot);
1923
1924         if (mid <= slot) {
1925                 free_extent_buffer(path->nodes[0]);
1926                 path->nodes[0] = right;
1927                 path->slots[0] -= mid;
1928                 path->slots[1] += 1;
1929         } else
1930                 free_extent_buffer(right);
1931
1932         BUG_ON(path->slots[0] < 0);
1933
1934         if (!double_split) {
1935                 return ret;
1936         }
1937
1938         right = btrfs_alloc_free_block(trans, root, root->leafsize,
1939                                        l->start, 0);
1940         if (IS_ERR(right))
1941                 return PTR_ERR(right);
1942
1943         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1944         btrfs_set_header_bytenr(right, right->start);
1945         btrfs_set_header_generation(right, trans->transid);
1946         btrfs_set_header_owner(right, root->root_key.objectid);
1947         btrfs_set_header_level(right, 0);
1948         write_extent_buffer(right, root->fs_info->fsid,
1949                             (unsigned long)btrfs_header_fsid(right),
1950                             BTRFS_FSID_SIZE);
1951
1952         btrfs_cpu_key_to_disk(&disk_key, ins_key);
1953         btrfs_set_header_nritems(right, 0);
1954         wret = insert_ptr(trans, root, path,
1955                           &disk_key, right->start,
1956                           path->slots[1], 1);
1957         if (wret)
1958                 ret = wret;
1959         if (path->slots[1] == 0) {
1960                 wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1961                 if (wret)
1962                         ret = wret;
1963         }
1964         free_extent_buffer(path->nodes[0]);
1965         path->nodes[0] = right;
1966         path->slots[0] = 0;
1967         return ret;
1968 }
1969
1970 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
1971                         struct btrfs_root *root,
1972                         struct btrfs_path *path,
1973                         u32 new_size)
1974 {
1975         int ret = 0;
1976         int slot;
1977         int slot_orig;
1978         struct extent_buffer *leaf;
1979         struct btrfs_item *item;
1980         u32 nritems;
1981         unsigned int data_end;
1982         unsigned int old_data_start;
1983         unsigned int old_size;
1984         unsigned int size_diff;
1985         int i;
1986
1987         slot_orig = path->slots[0];
1988         leaf = path->nodes[0];
1989
1990         nritems = btrfs_header_nritems(leaf);
1991         data_end = leaf_data_end(root, leaf);
1992
1993         slot = path->slots[0];
1994         old_data_start = btrfs_item_offset_nr(leaf, slot);
1995         old_size = btrfs_item_size_nr(leaf, slot);
1996         BUG_ON(old_size <= new_size);
1997         size_diff = old_size - new_size;
1998
1999         BUG_ON(slot < 0);
2000         BUG_ON(slot >= nritems);
2001
2002         /*
2003          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2004          */
2005         /* first correct the data pointers */
2006         for (i = slot; i < nritems; i++) {
2007                 u32 ioff;
2008                 item = btrfs_item_nr(leaf, i);
2009
2010                 if (!leaf->map_token) {
2011                         map_extent_buffer(leaf, (unsigned long)item,
2012                                         sizeof(struct btrfs_item),
2013                                         &leaf->map_token, &leaf->kaddr,
2014                                         &leaf->map_start, &leaf->map_len,
2015                                         KM_USER1);
2016                 }
2017
2018                 ioff = btrfs_item_offset(leaf, item);
2019                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2020         }
2021
2022         if (leaf->map_token) {
2023                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2024                 leaf->map_token = NULL;
2025         }
2026
2027         /* shift the data */
2028         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2029                       data_end + size_diff, btrfs_leaf_data(leaf) +
2030                       data_end, old_data_start + new_size - data_end);
2031
2032         item = btrfs_item_nr(leaf, slot);
2033         btrfs_set_item_size(leaf, item, new_size);
2034         btrfs_mark_buffer_dirty(leaf);
2035
2036         ret = 0;
2037         if (btrfs_leaf_free_space(root, leaf) < 0) {
2038                 btrfs_print_leaf(root, leaf);
2039                 BUG();
2040         }
2041         return ret;
2042 }
2043
2044 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2045                       struct btrfs_root *root, struct btrfs_path *path,
2046                       u32 data_size)
2047 {
2048         int ret = 0;
2049         int slot;
2050         int slot_orig;
2051         struct extent_buffer *leaf;
2052         struct btrfs_item *item;
2053         u32 nritems;
2054         unsigned int data_end;
2055         unsigned int old_data;
2056         unsigned int old_size;
2057         int i;
2058
2059         slot_orig = path->slots[0];
2060         leaf = path->nodes[0];
2061
2062         nritems = btrfs_header_nritems(leaf);
2063         data_end = leaf_data_end(root, leaf);
2064
2065         if (btrfs_leaf_free_space(root, leaf) < data_size) {
2066                 btrfs_print_leaf(root, leaf);
2067                 BUG();
2068         }
2069         slot = path->slots[0];
2070         old_data = btrfs_item_end_nr(leaf, slot);
2071
2072         BUG_ON(slot < 0);
2073         if (slot >= nritems) {
2074                 btrfs_print_leaf(root, leaf);
2075                 printk("slot %d too large, nritems %d\n", slot, nritems);
2076                 BUG_ON(1);
2077         }
2078
2079         /*
2080          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2081          */
2082         /* first correct the data pointers */
2083         for (i = slot; i < nritems; i++) {
2084                 u32 ioff;
2085                 item = btrfs_item_nr(leaf, i);
2086
2087                 if (!leaf->map_token) {
2088                         map_extent_buffer(leaf, (unsigned long)item,
2089                                         sizeof(struct btrfs_item),
2090                                         &leaf->map_token, &leaf->kaddr,
2091                                         &leaf->map_start, &leaf->map_len,
2092                                         KM_USER1);
2093                 }
2094                 ioff = btrfs_item_offset(leaf, item);
2095                 btrfs_set_item_offset(leaf, item, ioff - data_size);
2096         }
2097
2098         if (leaf->map_token) {
2099                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2100                 leaf->map_token = NULL;
2101         }
2102
2103         /* shift the data */
2104         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2105                       data_end - data_size, btrfs_leaf_data(leaf) +
2106                       data_end, old_data - data_end);
2107
2108         data_end = old_data;
2109         old_size = btrfs_item_size_nr(leaf, slot);
2110         item = btrfs_item_nr(leaf, slot);
2111         btrfs_set_item_size(leaf, item, old_size + data_size);
2112         btrfs_mark_buffer_dirty(leaf);
2113
2114         ret = 0;
2115         if (btrfs_leaf_free_space(root, leaf) < 0) {
2116                 btrfs_print_leaf(root, leaf);
2117                 BUG();
2118         }
2119         return ret;
2120 }
2121
2122 /*
2123  * Given a key and some data, insert an item into the tree.
2124  * This does all the path init required, making room in the tree if needed.
2125  */
2126 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans,
2127                             struct btrfs_root *root,
2128                             struct btrfs_path *path,
2129                             struct btrfs_key *cpu_key, u32 data_size)
2130 {
2131         struct extent_buffer *leaf;
2132         struct btrfs_item *item;
2133         int ret = 0;
2134         int slot;
2135         int slot_orig;
2136         u32 nritems;
2137         unsigned int data_end;
2138         struct btrfs_disk_key disk_key;
2139
2140         btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2141
2142         /* create a root if there isn't one */
2143         if (!root->node)
2144                 BUG();
2145
2146         ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
2147         if (ret == 0) {
2148                 return -EEXIST;
2149         }
2150         if (ret < 0)
2151                 goto out;
2152
2153         slot_orig = path->slots[0];
2154         leaf = path->nodes[0];
2155
2156         nritems = btrfs_header_nritems(leaf);
2157         data_end = leaf_data_end(root, leaf);
2158
2159         if (btrfs_leaf_free_space(root, leaf) <
2160             sizeof(struct btrfs_item) + data_size) {
2161                 btrfs_print_leaf(root, leaf);
2162                 printk("not enough freespace need %u have %d\n",
2163                        data_size, btrfs_leaf_free_space(root, leaf));
2164                 BUG();
2165         }
2166
2167         slot = path->slots[0];
2168         BUG_ON(slot < 0);
2169
2170         if (slot != nritems) {
2171                 int i;
2172                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2173
2174                 if (old_data < data_end) {
2175                         btrfs_print_leaf(root, leaf);
2176                         printk("slot %d old_data %d data_end %d\n",
2177                                slot, old_data, data_end);
2178                         BUG_ON(1);
2179                 }
2180                 /*
2181                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2182                  */
2183                 /* first correct the data pointers */
2184                 WARN_ON(leaf->map_token);
2185                 for (i = slot; i < nritems; i++) {
2186                         u32 ioff;
2187
2188                         item = btrfs_item_nr(leaf, i);
2189                         if (!leaf->map_token) {
2190                                 map_extent_buffer(leaf, (unsigned long)item,
2191                                         sizeof(struct btrfs_item),
2192                                         &leaf->map_token, &leaf->kaddr,
2193                                         &leaf->map_start, &leaf->map_len,
2194                                         KM_USER1);
2195                         }
2196
2197                         ioff = btrfs_item_offset(leaf, item);
2198                         btrfs_set_item_offset(leaf, item, ioff - data_size);
2199                 }
2200                 if (leaf->map_token) {
2201                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2202                         leaf->map_token = NULL;
2203                 }
2204
2205                 /* shift the items */
2206                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
2207                               btrfs_item_nr_offset(slot),
2208                               (nritems - slot) * sizeof(struct btrfs_item));
2209
2210                 /* shift the data */
2211                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2212                               data_end - data_size, btrfs_leaf_data(leaf) +
2213                               data_end, old_data - data_end);
2214                 data_end = old_data;
2215         }
2216
2217         /* setup the item for the new data */
2218         btrfs_set_item_key(leaf, &disk_key, slot);
2219         item = btrfs_item_nr(leaf, slot);
2220         btrfs_set_item_offset(leaf, item, data_end - data_size);
2221         btrfs_set_item_size(leaf, item, data_size);
2222         btrfs_set_header_nritems(leaf, nritems + 1);
2223         btrfs_mark_buffer_dirty(leaf);
2224
2225         ret = 0;
2226         if (slot == 0)
2227                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2228
2229         if (btrfs_leaf_free_space(root, leaf) < 0) {
2230                 btrfs_print_leaf(root, leaf);
2231                 BUG();
2232         }
2233 out:
2234         return ret;
2235 }
2236
2237 /*
2238  * Given a key and some data, insert an item into the tree.
2239  * This does all the path init required, making room in the tree if needed.
2240  */
2241 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2242                       *root, struct btrfs_key *cpu_key, void *data, u32
2243                       data_size)
2244 {
2245         int ret = 0;
2246         struct btrfs_path *path;
2247         struct extent_buffer *leaf;
2248         unsigned long ptr;
2249
2250         path = btrfs_alloc_path();
2251         BUG_ON(!path);
2252         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2253         if (!ret) {
2254                 leaf = path->nodes[0];
2255                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2256                 write_extent_buffer(leaf, data, ptr, data_size);
2257                 btrfs_mark_buffer_dirty(leaf);
2258         }
2259         btrfs_free_path(path);
2260         return ret;
2261 }
2262
2263 /*
2264  * delete the pointer from a given node.
2265  *
2266  * If the delete empties a node, the node is removed from the tree,
2267  * continuing all the way the root if required.  The root is converted into
2268  * a leaf if all the nodes are emptied.
2269  */
2270 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2271                    struct btrfs_path *path, int level, int slot)
2272 {
2273         struct extent_buffer *parent = path->nodes[level];
2274         u32 nritems;
2275         int ret = 0;
2276         int wret;
2277
2278         nritems = btrfs_header_nritems(parent);
2279         if (slot != nritems -1) {
2280                 memmove_extent_buffer(parent,
2281                               btrfs_node_key_ptr_offset(slot),
2282                               btrfs_node_key_ptr_offset(slot + 1),
2283                               sizeof(struct btrfs_key_ptr) *
2284                               (nritems - slot - 1));
2285         }
2286         nritems--;
2287         btrfs_set_header_nritems(parent, nritems);
2288         if (nritems == 0 && parent == root->node) {
2289                 BUG_ON(btrfs_header_level(root->node) != 1);
2290                 /* just turn the root into a leaf and break */
2291                 btrfs_set_header_level(root->node, 0);
2292         } else if (slot == 0) {
2293                 struct btrfs_disk_key disk_key;
2294
2295                 btrfs_node_key(parent, &disk_key, 0);
2296                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2297                 if (wret)
2298                         ret = wret;
2299         }
2300         btrfs_mark_buffer_dirty(parent);
2301         return ret;
2302 }
2303
2304 /*
2305  * delete the item at the leaf level in path.  If that empties
2306  * the leaf, remove it from the tree
2307  */
2308 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2309                    struct btrfs_path *path)
2310 {
2311         int slot;
2312         struct extent_buffer *leaf;
2313         struct btrfs_item *item;
2314         int doff;
2315         int dsize;
2316         int ret = 0;
2317         int wret;
2318         u32 nritems;
2319
2320         leaf = path->nodes[0];
2321         slot = path->slots[0];
2322         doff = btrfs_item_offset_nr(leaf, slot);
2323         dsize = btrfs_item_size_nr(leaf, slot);
2324         nritems = btrfs_header_nritems(leaf);
2325
2326         if (slot != nritems - 1) {
2327                 int i;
2328                 int data_end = leaf_data_end(root, leaf);
2329
2330                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2331                               data_end + dsize,
2332                               btrfs_leaf_data(leaf) + data_end,
2333                               doff - data_end);
2334
2335                 for (i = slot + 1; i < nritems; i++) {
2336                         u32 ioff;
2337
2338                         item = btrfs_item_nr(leaf, i);
2339                         if (!leaf->map_token) {
2340                                 map_extent_buffer(leaf, (unsigned long)item,
2341                                         sizeof(struct btrfs_item),
2342                                         &leaf->map_token, &leaf->kaddr,
2343                                         &leaf->map_start, &leaf->map_len,
2344                                         KM_USER1);
2345                         }
2346                         ioff = btrfs_item_offset(leaf, item);
2347                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2348                 }
2349
2350                 if (leaf->map_token) {
2351                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2352                         leaf->map_token = NULL;
2353                 }
2354
2355                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2356                               btrfs_item_nr_offset(slot + 1),
2357                               sizeof(struct btrfs_item) *
2358                               (nritems - slot - 1));
2359         }
2360         btrfs_set_header_nritems(leaf, nritems - 1);
2361         nritems--;
2362
2363         /* delete the leaf if we've emptied it */
2364         if (nritems == 0) {
2365                 if (leaf == root->node) {
2366                         btrfs_set_header_level(leaf, 0);
2367                 } else {
2368                         clean_tree_block(trans, root, leaf);
2369                         wait_on_tree_block_writeback(root, leaf);
2370                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
2371                         if (wret)
2372                                 ret = wret;
2373                         wret = btrfs_free_extent(trans, root,
2374                                                  leaf->start, leaf->len, 1);
2375                         if (wret)
2376                                 ret = wret;
2377                 }
2378         } else {
2379                 int used = leaf_space_used(leaf, 0, nritems);
2380                 if (slot == 0) {
2381                         struct btrfs_disk_key disk_key;
2382
2383                         btrfs_item_key(leaf, &disk_key, 0);
2384                         wret = fixup_low_keys(trans, root, path,
2385                                               &disk_key, 1);
2386                         if (wret)
2387                                 ret = wret;
2388                 }
2389
2390                 /* delete the leaf if it is mostly empty */
2391                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
2392                         /* push_leaf_left fixes the path.
2393                          * make sure the path still points to our leaf
2394                          * for possible call to del_ptr below
2395                          */
2396                         slot = path->slots[1];
2397                         extent_buffer_get(leaf);
2398
2399                         wret = push_leaf_right(trans, root, path, 1);
2400                         if (wret < 0 && wret != -ENOSPC)
2401                                 ret = wret;
2402
2403                         if (path->nodes[0] == leaf &&
2404                             btrfs_header_nritems(leaf)) {
2405                                 wret = push_leaf_left(trans, root, path, 1);
2406                                 if (wret < 0 && wret != -ENOSPC)
2407                                         ret = wret;
2408                         }
2409
2410                         if (btrfs_header_nritems(leaf) == 0) {
2411                                 u64 bytenr = leaf->start;
2412                                 u32 blocksize = leaf->len;
2413
2414                                 clean_tree_block(trans, root, leaf);
2415                                 wait_on_tree_block_writeback(root, leaf);
2416
2417                                 wret = del_ptr(trans, root, path, 1, slot);
2418                                 if (wret)
2419                                         ret = wret;
2420
2421                                 free_extent_buffer(leaf);
2422                                 wret = btrfs_free_extent(trans, root, bytenr,
2423                                                          blocksize, 1);
2424                                 if (wret)
2425                                         ret = wret;
2426                         } else {
2427                                 btrfs_mark_buffer_dirty(leaf);
2428                                 free_extent_buffer(leaf);
2429                         }
2430                 } else {
2431                         btrfs_mark_buffer_dirty(leaf);
2432                 }
2433         }
2434         return ret;
2435 }
2436
2437 /*
2438  * walk up the tree as far as required to find the next leaf.
2439  * returns 0 if it found something or 1 if there are no greater leaves.
2440  * returns < 0 on io errors.
2441  */
2442 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2443 {
2444         int slot;
2445         int level = 1;
2446         u64 bytenr;
2447         struct extent_buffer *c;
2448         struct extent_buffer *next = NULL;
2449
2450         while(level < BTRFS_MAX_LEVEL) {
2451                 if (!path->nodes[level])
2452                         return 1;
2453
2454                 slot = path->slots[level] + 1;
2455                 c = path->nodes[level];
2456                 if (slot >= btrfs_header_nritems(c)) {
2457                         level++;
2458                         continue;
2459                 }
2460
2461                 bytenr = btrfs_node_blockptr(c, slot);
2462                 if (next)
2463                         free_extent_buffer(next);
2464
2465                 if (path->reada)
2466                         reada_for_search(root, path, level, slot);
2467
2468                 next = read_tree_block(root, bytenr,
2469                                        btrfs_level_size(root, level -1));
2470                 break;
2471         }
2472         path->slots[level] = slot;
2473         while(1) {
2474                 level--;
2475                 c = path->nodes[level];
2476                 free_extent_buffer(c);
2477                 path->nodes[level] = next;
2478                 path->slots[level] = 0;
2479                 if (!level)
2480                         break;
2481                 if (path->reada)
2482                         reada_for_search(root, path, level, 0);
2483                 next = read_tree_block(root, btrfs_node_blockptr(next, 0),
2484                                        btrfs_level_size(root, level - 1));
2485         }
2486         return 0;
2487 }