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 "ctree.h"
  20 #include "disk-io.h"
  21 #include "transaction.h"
  22 #include "print-tree.h"
  23
  24 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  25                       *root, struct btrfs_path *path, int level);
  26 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  27                       *root, struct btrfs_key *ins_key,
  28                       struct btrfs_path *path, int data_size);
  29 static int push_node_left(struct btrfs_trans_handle *trans,
  30                           struct btrfs_root *root, struct extent_buffer *dst,
  31                           struct extent_buffer *src);
  32 static int balance_node_right(struct btrfs_trans_handle *trans,
  33                               struct btrfs_root *root,
  34                               struct extent_buffer *dst_buf,
  35                               struct extent_buffer *src_buf);
  36 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  37                    struct btrfs_path *path, int level, int slot);
  38
  39 inline void btrfs_init_path(struct btrfs_path *p)
  40 {
  41         memset(p, 0, sizeof(*p));
  42 }
  43
  44 struct btrfs_path *btrfs_alloc_path(void)
  45 {
  46         struct btrfs_path *path;
  47         path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
  48         if (path) {
  49                 btrfs_init_path(path);
  50                 path->reada = 1;
  51         }
  52         return path;
  53 }
  54
  55 void btrfs_free_path(struct btrfs_path *p)
  56 {
  57         btrfs_release_path(NULL, p);
  58         kmem_cache_free(btrfs_path_cachep, p);
  59 }
  60
  61 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
  62 {
  63         int i;
  64         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  65                 if (!p->nodes[i])
  66                         break;
  67                 free_extent_buffer(p->nodes[i]);
  68         }
  69         memset(p, 0, sizeof(*p));
  70 }
  71
  72 static int __btrfs_cow_block(struct btrfs_trans_handle *trans,
  73                              struct btrfs_root *root,
  74                              struct extent_buffer *buf,
  75                              struct extent_buffer *parent, int parent_slot,
  76                              struct extent_buffer **cow_ret,
  77                              u64 search_start, u64 empty_size)
  78 {
  79         struct extent_buffer *cow;
  80         int ret = 0;
  81         int different_trans = 0;
  82
  83         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
  84
  85         cow = btrfs_alloc_free_block(trans, root, buf->len,
  86                                      search_start, empty_size);
  87         if (IS_ERR(cow))
  88                 return PTR_ERR(cow);
  89
  90         copy_extent_buffer(cow, buf, 0, 0, cow->len);
  91         btrfs_set_header_bytenr(cow, cow->start);
  92         btrfs_set_header_generation(cow, trans->transid);
  93         btrfs_set_header_owner(cow, root->root_key.objectid);
  94
  95         WARN_ON(btrfs_header_generation(buf) > trans->transid);
  96         if (btrfs_header_generation(buf) != trans->transid) {
  97                 different_trans = 1;
  98                 ret = btrfs_inc_ref(trans, root, buf);
  99                 if (ret)
 100                         return ret;
 101         } else {
 102                 clean_tree_block(trans, root, buf);
 103         }
 104
 105         if (buf == root->node) {
 106                 root->node = cow;
 107                 extent_buffer_get(cow);
 108                 if (buf != root->commit_root) {
 109                         btrfs_free_extent(trans, root, buf->start,
 110                                           buf->len, 1);
 111                 }
 112                 free_extent_buffer(buf);
 113         } else {
 114                 btrfs_set_node_blockptr(parent, parent_slot,
 115                                         cow->start);
 116                 btrfs_mark_buffer_dirty(parent);
 117                 WARN_ON(btrfs_header_generation(parent) != trans->transid);
 118                 btrfs_free_extent(trans, root, buf->start, buf->len, 1);
 119         }
 120         free_extent_buffer(buf);
 121         btrfs_mark_buffer_dirty(cow);
 122         *cow_ret = cow;
 123         return 0;
 124 }
 125
 126 int btrfs_cow_block(struct btrfs_trans_handle *trans,
 127                     struct btrfs_root *root, struct extent_buffer *buf,
 128                     struct extent_buffer *parent, int parent_slot,
 129                     struct extent_buffer **cow_ret)
 130 {
 131         u64 search_start;
 132         int ret;
 133         if (trans->transaction != root->fs_info->running_transaction) {
 134                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 135                        root->fs_info->running_transaction->transid);
 136                 WARN_ON(1);
 137         }
 138         if (trans->transid != root->fs_info->generation) {
 139                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 140                        root->fs_info->generation);
 141                 WARN_ON(1);
 142         }
 143         if (btrfs_header_generation(buf) == trans->transid) {
 144                 *cow_ret = buf;
 145                 return 0;
 146         }
 147
 148         search_start = buf->start & ~((u64)BTRFS_BLOCK_GROUP_SIZE - 1);
 149         ret = __btrfs_cow_block(trans, root, buf, parent,
 150                                  parent_slot, cow_ret, search_start, 0);
 151         return ret;
 152 }
 153
 154 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 155 {
 156         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 157                 return 1;
 158         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 159                 return 1;
 160         return 0;
 161 }
 162
 163 static int should_defrag_leaf(struct extent_buffer *leaf)
 164 {
 165         struct btrfs_key key;
 166         u32 nritems;
 167
 168         if (btrfs_buffer_defrag(leaf))
 169                 return 1;
 170
 171         nritems = btrfs_header_nritems(leaf);
 172         if (nritems == 0)
 173                 return 0;
 174
 175         btrfs_item_key_to_cpu(leaf, &key, 0);
 176         if (key.type == BTRFS_DIR_ITEM_KEY)
 177                 return 1;
 178
 179
 180         btrfs_item_key_to_cpu(leaf, &key, nritems - 1);
 181         if (key.type == BTRFS_DIR_ITEM_KEY)
 182                 return 1;
 183         if (nritems > 4) {
 184                 btrfs_item_key_to_cpu(leaf, &key, nritems / 2);
 185                 if (key.type == BTRFS_DIR_ITEM_KEY)
 186                         return 1;
 187         }
 188         return 0;
 189 }
 190
 191 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 192                        struct btrfs_root *root, struct extent_buffer *parent,
 193                        int cache_only, u64 *last_ret)
 194 {
 195         struct extent_buffer *cur;
 196         struct extent_buffer *tmp;
 197         u64 blocknr;
 198         u64 search_start = *last_ret;
 199         u64 last_block = 0;
 200         u64 other;
 201         u32 parent_nritems;
 202         int start_slot;
 203         int end_slot;
 204         int i;
 205         int err = 0;
 206         int parent_level;
 207         int uptodate;
 208         u32 blocksize;
 209
 210         if (trans->transaction != root->fs_info->running_transaction) {
 211                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 212                        root->fs_info->running_transaction->transid);
 213                 WARN_ON(1);
 214         }
 215         if (trans->transid != root->fs_info->generation) {
 216                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 217                        root->fs_info->generation);
 218                 WARN_ON(1);
 219         }
 220         parent_level = btrfs_header_level(parent);
 221
 222         parent_nritems = btrfs_header_nritems(parent);
 223         blocksize = btrfs_level_size(root, parent_level - 1);
 224
 225         start_slot = 0;
 226         end_slot = parent_nritems;
 227
 228         if (parent_nritems == 1)
 229                 return 0;
 230
 231         for (i = start_slot; i < end_slot; i++) {
 232                 int close = 1;
 233                 blocknr = btrfs_node_blockptr(parent, i);
 234                 if (last_block == 0)
 235                         last_block = blocknr;
 236                 if (i > 0) {
 237                         other = btrfs_node_blockptr(parent, i - 1);
 238                         close = close_blocks(blocknr, other, blocksize);
 239                 }
 240                 if (close && i < end_slot - 1) {
 241                         other = btrfs_node_blockptr(parent, i + 1);
 242                         close = close_blocks(blocknr, other, blocksize);
 243                 }
 244                 if (close) {
 245                         last_block = blocknr;
 246                         continue;
 247                 }
 248
 249                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
 250                 if (cur)
 251                         uptodate = btrfs_buffer_uptodate(cur);
 252                 else
 253                         uptodate = 0;
 254                 if (!cur || !uptodate ||
 255                     (parent_level != 1 && !btrfs_buffer_defrag(cur)) ||
 256                     (parent_level == 1 && !should_defrag_leaf(cur))) {
 257                         if (cache_only) {
 258                                 free_extent_buffer(cur);
 259                                 continue;
 260                         }
 261                         if (!cur) {
 262                                 cur = read_tree_block(root, blocknr,
 263                                                          blocksize);
 264                         } else if (!uptodate) {
 265                                 btrfs_read_buffer(cur);
 266                         }
 267                 }
 268                 if (search_start == 0)
 269                         search_start = last_block;
 270
 271                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 272                                         &tmp, search_start,
 273                                         min(16 * blocksize,
 274                                             (end_slot - i) * blocksize));
 275                 if (err) {
 276                         free_extent_buffer(cur);
 277                         break;
 278                 }
 279                 search_start = tmp->start;
 280                 *last_ret = search_start;
 281                 if (parent_level == 1)
 282                         btrfs_clear_buffer_defrag(tmp);
 283                 btrfs_set_buffer_defrag_done(tmp);
 284                 free_extent_buffer(tmp);
 285         }
 286         return err;
 287 }
 288
 289 /*
 290  * The leaf data grows from end-to-front in the node.
 291  * this returns the address of the start of the last item,
 292  * which is the stop of the leaf data stack
 293  */
 294 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 295                                          struct extent_buffer *leaf)
 296 {
 297         u32 nr = btrfs_header_nritems(leaf);
 298         if (nr == 0)
 299                 return BTRFS_LEAF_DATA_SIZE(root);
 300         return btrfs_item_offset_nr(leaf, nr - 1);
 301 }
 302
 303 /*
 304  * compare two keys in a memcmp fashion
 305  */
 306 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 307 {
 308         struct btrfs_key k1;
 309
 310         btrfs_disk_key_to_cpu(&k1, disk);
 311
 312         if (k1.objectid > k2->objectid)
 313                 return 1;
 314         if (k1.objectid < k2->objectid)
 315                 return -1;
 316         if (k1.type > k2->type)
 317                 return 1;
 318         if (k1.type < k2->type)
 319                 return -1;
 320         if (k1.offset > k2->offset)
 321                 return 1;
 322         if (k1.offset < k2->offset)
 323                 return -1;
 324         return 0;
 325 }
 326
 327 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 328                       int level)
 329 {
 330         struct extent_buffer *parent = NULL;
 331         struct extent_buffer *node = path->nodes[level];
 332         struct btrfs_disk_key parent_key;
 333         struct btrfs_disk_key node_key;
 334         int parent_slot;
 335         int slot;
 336         struct btrfs_key cpukey;
 337         u32 nritems = btrfs_header_nritems(node);
 338
 339         if (path->nodes[level + 1])
 340                 parent = path->nodes[level + 1];
 341
 342         slot = path->slots[level];
 343         BUG_ON(nritems == 0);
 344         if (parent) {
 345                 parent_slot = path->slots[level + 1];
 346                 btrfs_node_key(parent, &parent_key, parent_slot);
 347                 btrfs_node_key(node, &node_key, 0);
 348                 BUG_ON(memcmp(&parent_key, &node_key,
 349                               sizeof(struct btrfs_disk_key)));
 350                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 351                        btrfs_header_bytenr(node));
 352         }
 353         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 354         if (slot != 0) {
 355                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 356                 btrfs_node_key(node, &node_key, slot);
 357                 BUG_ON(comp_keys(&node_key, &cpukey) <= 0);
 358         }
 359         if (slot < nritems - 1) {
 360                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 361                 btrfs_node_key(node, &node_key, slot);
 362                 BUG_ON(comp_keys(&node_key, &cpukey) >= 0);
 363         }
 364         return 0;
 365 }
 366
 367 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 368                       int level)
 369 {
 370         struct extent_buffer *leaf = path->nodes[level];
 371         struct extent_buffer *parent = NULL;
 372         int parent_slot;
 373         struct btrfs_key cpukey;
 374         struct btrfs_disk_key parent_key;
 375         struct btrfs_disk_key leaf_key;
 376         int slot = path->slots[0];
 377
 378         u32 nritems = btrfs_header_nritems(leaf);
 379
 380         if (path->nodes[level + 1])
 381                 parent = path->nodes[level + 1];
 382
 383         if (nritems == 0)
 384                 return 0;
 385
 386         if (parent) {
 387                 parent_slot = path->slots[level + 1];
 388                 btrfs_node_key(parent, &parent_key, parent_slot);
 389                 btrfs_item_key(leaf, &leaf_key, 0);
 390
 391                 BUG_ON(memcmp(&parent_key, &leaf_key,
 392                        sizeof(struct btrfs_disk_key)));
 393                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 394                        btrfs_header_bytenr(leaf));
 395         }
 396 #if 0
 397         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 398                 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
 399                 btrfs_item_key(leaf, &leaf_key, i);
 400                 if (comp_keys(&leaf_key, &cpukey) >= 0) {
 401                         btrfs_print_leaf(root, leaf);
 402                         printk("slot %d offset bad key\n", i);
 403                         BUG_ON(1);
 404                 }
 405                 if (btrfs_item_offset_nr(leaf, i) !=
 406                         btrfs_item_end_nr(leaf, i + 1)) {
 407                         btrfs_print_leaf(root, leaf);
 408                         printk("slot %d offset bad\n", i);
 409                         BUG_ON(1);
 410                 }
 411                 if (i == 0) {
 412                         if (btrfs_item_offset_nr(leaf, i) +
 413                                btrfs_item_size_nr(leaf, i) !=
 414                                BTRFS_LEAF_DATA_SIZE(root)) {
 415                                 btrfs_print_leaf(root, leaf);
 416                                 printk("slot %d first offset bad\n", i);
 417                                 BUG_ON(1);
 418                         }
 419                 }
 420         }
 421         if (nritems > 0) {
 422                 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
 423                                 btrfs_print_leaf(root, leaf);
 424                                 printk("slot %d bad size \n", nritems - 1);
 425                                 BUG_ON(1);
 426                 }
 427         }
 428 #endif
 429         if (slot != 0 && slot < nritems - 1) {
 430                 btrfs_item_key(leaf, &leaf_key, slot);
 431                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 432                 if (comp_keys(&leaf_key, &cpukey) <= 0) {
 433                         btrfs_print_leaf(root, leaf);
 434                         printk("slot %d offset bad key\n", slot);
 435                         BUG_ON(1);
 436                 }
 437                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 438                        btrfs_item_end_nr(leaf, slot)) {
 439                         btrfs_print_leaf(root, leaf);
 440                         printk("slot %d offset bad\n", slot);
 441                         BUG_ON(1);
 442                 }
 443         }
 444         if (slot < nritems - 1) {
 445                 btrfs_item_key(leaf, &leaf_key, slot);
 446                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 447                 BUG_ON(comp_keys(&leaf_key, &cpukey) >= 0);
 448                 if (btrfs_item_offset_nr(leaf, slot) !=
 449                         btrfs_item_end_nr(leaf, slot + 1)) {
 450                         btrfs_print_leaf(root, leaf);
 451                         printk("slot %d offset bad\n", slot);
 452                         BUG_ON(1);
 453                 }
 454         }
 455         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 456                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 457         return 0;
 458 }
 459
 460 static int check_block(struct btrfs_root *root, struct btrfs_path *path,
 461                         int level)
 462 {
 463         return 0;
 464 #if 0
 465         struct extent_buffer *buf = path->nodes[level];
 466
 467         if (memcmp_extent_buffer(buf, root->fs_info->fsid,
 468                                  (unsigned long)btrfs_header_fsid(buf),
 469                                  BTRFS_FSID_SIZE)) {
 470                 printk("warning bad block %Lu\n", buf->start);
 471                 return 1;
 472         }
 473 #endif
 474         if (level == 0)
 475                 return check_leaf(root, path, level);
 476         return check_node(root, path, level);
 477 }
 478
 479 /*
 480  * search for key in the extent_buffer.  The items start at offset p,
 481  * and they are item_size apart.  There are 'max' items in p.
 482  *
 483  * the slot in the array is returned via slot, and it points to
 484  * the place where you would insert key if it is not found in
 485  * the array.
 486  *
 487  * slot may point to max if the key is bigger than all of the keys
 488  */
 489 static int generic_bin_search(struct extent_buffer *eb, unsigned long p,
 490                               int item_size, struct btrfs_key *key,
 491                               int max, int *slot)
 492 {
 493         int low = 0;
 494         int high = max;
 495         int mid;
 496         int ret;
 497         struct btrfs_disk_key *tmp = NULL;
 498         struct btrfs_disk_key unaligned;
 499         unsigned long offset;
 500         char *map_token = NULL;
 501         char *kaddr = NULL;
 502         unsigned long map_start = 0;
 503         unsigned long map_len = 0;
 504         int err;
 505
 506         while(low < high) {
 507                 mid = (low + high) / 2;
 508                 offset = p + mid * item_size;
 509
 510                 if (!map_token || offset < map_start ||
 511                     (offset + sizeof(struct btrfs_disk_key)) >
 512                     map_start + map_len) {
 513                         if (map_token) {
 514                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 515                                 map_token = NULL;
 516                         }
 517                         err = map_extent_buffer(eb, offset,
 518                                                 sizeof(struct btrfs_disk_key),
 519                                                 &map_token, &kaddr,
 520                                                 &map_start, &map_len, KM_USER0);
 521
 522                         if (!err) {
 523                                 tmp = (struct btrfs_disk_key *)(kaddr + offset -
 524                                                         map_start);
 525                         } else {
 526                                 read_extent_buffer(eb, &unaligned,
 527                                                    offset, sizeof(unaligned));
 528                                 tmp = &unaligned;
 529                         }
 530
 531                 } else {
 532                         tmp = (struct btrfs_disk_key *)(kaddr + offset -
 533                                                         map_start);
 534                 }
 535                 ret = comp_keys(tmp, key);
 536
 537                 if (ret < 0)
 538                         low = mid + 1;
 539                 else if (ret > 0)
 540                         high = mid;
 541                 else {
 542                         *slot = mid;
 543                         if (map_token)
 544                                 unmap_extent_buffer(eb, map_token, KM_USER0);
 545                         return 0;
 546                 }
 547         }
 548         *slot = low;
 549         if (map_token)
 550                 unmap_extent_buffer(eb, map_token, KM_USER0);
 551         return 1;
 552 }
 553
 554 /*
 555  * simple bin_search frontend that does the right thing for
 556  * leaves vs nodes
 557  */
 558 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
 559                       int level, int *slot)
 560 {
 561         if (level == 0) {
 562                 return generic_bin_search(eb,
 563                                           offsetof(struct btrfs_leaf, items),
 564                                           sizeof(struct btrfs_item),
 565                                           key, btrfs_header_nritems(eb),
 566                                           slot);
 567         } else {
 568                 return generic_bin_search(eb,
 569                                           offsetof(struct btrfs_node, ptrs),
 570                                           sizeof(struct btrfs_key_ptr),
 571                                           key, btrfs_header_nritems(eb),
 572                                           slot);
 573         }
 574         return -1;
 575 }
 576
 577 static struct extent_buffer *read_node_slot(struct btrfs_root *root,
 578                                    struct extent_buffer *parent, int slot)
 579 {
 580         if (slot < 0)
 581                 return NULL;
 582         if (slot >= btrfs_header_nritems(parent))
 583                 return NULL;
 584         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
 585                        btrfs_level_size(root, btrfs_header_level(parent) - 1));
 586 }
 587
 588 static int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root
 589                          *root, struct btrfs_path *path, int level)
 590 {
 591         struct extent_buffer *right = NULL;
 592         struct extent_buffer *mid;
 593         struct extent_buffer *left = NULL;
 594         struct extent_buffer *parent = NULL;
 595         int ret = 0;
 596         int wret;
 597         int pslot;
 598         int orig_slot = path->slots[level];
 599         int err_on_enospc = 0;
 600         u64 orig_ptr;
 601
 602         if (level == 0)
 603                 return 0;
 604
 605         mid = path->nodes[level];
 606         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 607
 608         if (level < BTRFS_MAX_LEVEL - 1)
 609                 parent = path->nodes[level + 1];
 610         pslot = path->slots[level + 1];
 611
 612         /*
 613          * deal with the case where there is only one pointer in the root
 614          * by promoting the node below to a root
 615          */
 616         if (!parent) {
 617                 struct extent_buffer *child;
 618
 619                 if (btrfs_header_nritems(mid) != 1)
 620                         return 0;
 621
 622                 /* promote the child to a root */
 623                 child = read_node_slot(root, mid, 0);
 624                 BUG_ON(!child);
 625                 root->node = child;
 626                 path->nodes[level] = NULL;
 627                 clean_tree_block(trans, root, mid);
 628                 wait_on_tree_block_writeback(root, mid);
 629                 /* once for the path */
 630                 free_extent_buffer(mid);
 631                 ret = btrfs_free_extent(trans, root, mid->start, mid->len, 1);
 632                 /* once for the root ptr */
 633                 free_extent_buffer(mid);
 634                 return ret;
 635         }
 636         if (btrfs_header_nritems(mid) >
 637             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 638                 return 0;
 639
 640         if (btrfs_header_nritems(mid) < 2)
 641                 err_on_enospc = 1;
 642
 643         left = read_node_slot(root, parent, pslot - 1);
 644         if (left) {
 645                 wret = btrfs_cow_block(trans, root, left,
 646                                        parent, pslot - 1, &left);
 647                 if (wret) {
 648                         ret = wret;
 649                         goto enospc;
 650                 }
 651         }
 652         right = read_node_slot(root, parent, pslot + 1);
 653         if (right) {
 654                 wret = btrfs_cow_block(trans, root, right,
 655                                        parent, pslot + 1, &right);
 656                 if (wret) {
 657                         ret = wret;
 658                         goto enospc;
 659                 }
 660         }
 661
 662         /* first, try to make some room in the middle buffer */
 663         if (left) {
 664                 orig_slot += btrfs_header_nritems(left);
 665                 wret = push_node_left(trans, root, left, mid);
 666                 if (wret < 0)
 667                         ret = wret;
 668                 if (btrfs_header_nritems(mid) < 2)
 669                         err_on_enospc = 1;
 670         }
 671
 672         /*
 673          * then try to empty the right most buffer into the middle
 674          */
 675         if (right) {
 676                 wret = push_node_left(trans, root, mid, right);
 677                 if (wret < 0 && wret != -ENOSPC)
 678                         ret = wret;
 679                 if (btrfs_header_nritems(right) == 0) {
 680                         u64 bytenr = right->start;
 681                         u32 blocksize = right->len;
 682
 683                         clean_tree_block(trans, root, right);
 684                         wait_on_tree_block_writeback(root, right);
 685                         free_extent_buffer(right);
 686                         right = NULL;
 687                         wret = del_ptr(trans, root, path, level + 1, pslot +
 688                                        1);
 689                         if (wret)
 690                                 ret = wret;
 691                         wret = btrfs_free_extent(trans, root, bytenr,
 692                                                  blocksize, 1);
 693                         if (wret)
 694                                 ret = wret;
 695                 } else {
 696                         struct btrfs_disk_key right_key;
 697                         btrfs_node_key(right, &right_key, 0);
 698                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 699                         btrfs_mark_buffer_dirty(parent);
 700                 }
 701         }
 702         if (btrfs_header_nritems(mid) == 1) {
 703                 /*
 704                  * we're not allowed to leave a node with one item in the
 705                  * tree during a delete.  A deletion from lower in the tree
 706                  * could try to delete the only pointer in this node.
 707                  * So, pull some keys from the left.
 708                  * There has to be a left pointer at this point because
 709                  * otherwise we would have pulled some pointers from the
 710                  * right
 711                  */
 712                 BUG_ON(!left);
 713                 wret = balance_node_right(trans, root, mid, left);
 714                 if (wret < 0) {
 715                         ret = wret;
 716                         goto enospc;
 717                 }
 718                 BUG_ON(wret == 1);
 719         }
 720         if (btrfs_header_nritems(mid) == 0) {
 721                 /* we've managed to empty the middle node, drop it */
 722                 u64 bytenr = mid->start;
 723                 u32 blocksize = mid->len;
 724                 clean_tree_block(trans, root, mid);
 725                 wait_on_tree_block_writeback(root, mid);
 726                 free_extent_buffer(mid);
 727                 mid = NULL;
 728                 wret = del_ptr(trans, root, path, level + 1, pslot);
 729                 if (wret)
 730                         ret = wret;
 731                 wret = btrfs_free_extent(trans, root, bytenr, blocksize, 1);
 732                 if (wret)
 733                         ret = wret;
 734         } else {
 735                 /* update the parent key to reflect our changes */
 736                 struct btrfs_disk_key mid_key;
 737                 btrfs_node_key(mid, &mid_key, 0);
 738                 btrfs_set_node_key(parent, &mid_key, pslot);
 739                 btrfs_mark_buffer_dirty(parent);
 740         }
 741
 742         /* update the path */
 743         if (left) {
 744                 if (btrfs_header_nritems(left) > orig_slot) {
 745                         extent_buffer_get(left);
 746                         path->nodes[level] = left;
 747                         path->slots[level + 1] -= 1;
 748                         path->slots[level] = orig_slot;
 749                         if (mid)
 750                                 free_extent_buffer(mid);
 751                 } else {
 752                         orig_slot -= btrfs_header_nritems(left);
 753                         path->slots[level] = orig_slot;
 754                 }
 755         }
 756         /* double check we haven't messed things up */
 757         check_block(root, path, level);
 758         if (orig_ptr !=
 759             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 760                 BUG();
 761 enospc:
 762         if (right)
 763                 free_extent_buffer(right);
 764         if (left)
 765                 free_extent_buffer(left);
 766         return ret;
 767 }
 768
 769 /* returns zero if the push worked, non-zero otherwise */
 770 static int push_nodes_for_insert(struct btrfs_trans_handle *trans,
 771                                 struct btrfs_root *root,
 772                                 struct btrfs_path *path, int level)
 773 {
 774         struct extent_buffer *right = NULL;
 775         struct extent_buffer *mid;
 776         struct extent_buffer *left = NULL;
 777         struct extent_buffer *parent = NULL;
 778         int ret = 0;
 779         int wret;
 780         int pslot;
 781         int orig_slot = path->slots[level];
 782         u64 orig_ptr;
 783
 784         if (level == 0)
 785                 return 1;
 786
 787         mid = path->nodes[level];
 788         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 789
 790         if (level < BTRFS_MAX_LEVEL - 1)
 791                 parent = path->nodes[level + 1];
 792         pslot = path->slots[level + 1];
 793
 794         if (!parent)
 795                 return 1;
 796
 797         left = read_node_slot(root, parent, pslot - 1);
 798
 799         /* first, try to make some room in the middle buffer */
 800         if (left) {
 801                 u32 left_nr;
 802                 left_nr = btrfs_header_nritems(left);
 803                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 804                         wret = 1;
 805                 } else {
 806                         ret = btrfs_cow_block(trans, root, left, parent,
 807                                               pslot - 1, &left);
 808                         if (ret)
 809                                 wret = 1;
 810                         else {
 811                                 wret = push_node_left(trans, root,
 812                                                       left, mid);
 813                         }
 814                 }
 815                 if (wret < 0)
 816                         ret = wret;
 817                 if (wret == 0) {
 818                         struct btrfs_disk_key disk_key;
 819                         orig_slot += left_nr;
 820                         btrfs_node_key(mid, &disk_key, 0);
 821                         btrfs_set_node_key(parent, &disk_key, pslot);
 822                         btrfs_mark_buffer_dirty(parent);
 823                         if (btrfs_header_nritems(left) > orig_slot) {
 824                                 path->nodes[level] = left;
 825                                 path->slots[level + 1] -= 1;
 826                                 path->slots[level] = orig_slot;
 827                                 free_extent_buffer(mid);
 828                         } else {
 829                                 orig_slot -=
 830                                         btrfs_header_nritems(left);
 831                                 path->slots[level] = orig_slot;
 832                                 free_extent_buffer(left);
 833                         }
 834                         return 0;
 835                 }
 836                 free_extent_buffer(left);
 837         }
 838         right= read_node_slot(root, parent, pslot + 1);
 839
 840         /*
 841          * then try to empty the right most buffer into the middle
 842          */
 843         if (right) {
 844                 u32 right_nr;
 845                 right_nr = btrfs_header_nritems(right);
 846                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 847                         wret = 1;
 848                 } else {
 849                         ret = btrfs_cow_block(trans, root, right,
 850                                               parent, pslot + 1,
 851                                               &right);
 852                         if (ret)
 853                                 wret = 1;
 854                         else {
 855                                 wret = balance_node_right(trans, root,
 856                                                           right, mid);
 857                         }
 858                 }
 859                 if (wret < 0)
 860                         ret = wret;
 861                 if (wret == 0) {
 862                         struct btrfs_disk_key disk_key;
 863
 864                         btrfs_node_key(right, &disk_key, 0);
 865                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
 866                         btrfs_mark_buffer_dirty(parent);
 867
 868                         if (btrfs_header_nritems(mid) <= orig_slot) {
 869                                 path->nodes[level] = right;
 870                                 path->slots[level + 1] += 1;
 871                                 path->slots[level] = orig_slot -
 872                                         btrfs_header_nritems(mid);
 873                                 free_extent_buffer(mid);
 874                         } else {
 875                                 free_extent_buffer(right);
 876                         }
 877                         return 0;
 878                 }
 879                 free_extent_buffer(right);
 880         }
 881         return 1;
 882 }
 883
 884 /*
 885  * readahead one full node of leaves
 886  */
 887 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 888                              int level, int slot)
 889 {
 890         struct extent_buffer *node;
 891         u32 nritems;
 892         u64 search;
 893         u64 lowest_read;
 894         u64 highest_read;
 895         u64 nread = 0;
 896         int direction = path->reada;
 897         struct extent_buffer *eb;
 898         u32 nr;
 899         u32 blocksize;
 900         u32 nscan = 0;
 901
 902         if (level == 0)
 903                 return;
 904
 905         if (!path->nodes[level])
 906                 return;
 907
 908         node = path->nodes[level];
 909         search = btrfs_node_blockptr(node, slot);
 910         blocksize = btrfs_level_size(root, level - 1);
 911         eb = btrfs_find_tree_block(root, search, blocksize);
 912         if (eb) {
 913                 free_extent_buffer(eb);
 914                 return;
 915         }
 916
 917         highest_read = search;
 918         lowest_read = search;
 919
 920         nritems = btrfs_header_nritems(node);
 921         nr = slot;
 922         while(1) {
 923                 if (direction < 0) {
 924                         if (nr == 0)
 925                                 break;
 926                         nr--;
 927                 } else if (direction > 0) {
 928                         nr++;
 929                         if (nr >= nritems)
 930                                 break;
 931                 }
 932                 search = btrfs_node_blockptr(node, nr);
 933                 if ((search >= lowest_read && search <= highest_read) ||
 934                     (search < lowest_read && lowest_read - search <= 32768) ||
 935                     (search > highest_read && search - highest_read <= 32768)) {
 936                         readahead_tree_block(root, search, blocksize);
 937                         nread += blocksize;
 938                 }
 939                 nscan++;
 940                 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
 941                         break;
 942                 if(nread > (1024 * 1024) || nscan > 128)
 943                         break;
 944
 945                 if (search < lowest_read)
 946                         lowest_read = search;
 947                 if (search > highest_read)
 948                         highest_read = search;
 949         }
 950 }
 951 /*
 952  * look for key in the tree.  path is filled in with nodes along the way
 953  * if key is found, we return zero and you can find the item in the leaf
 954  * level of the path (level 0)
 955  *
 956  * If the key isn't found, the path points to the slot where it should
 957  * be inserted, and 1 is returned.  If there are other errors during the
 958  * search a negative error number is returned.
 959  *
 960  * if ins_len > 0, nodes and leaves will be split as we walk down the
 961  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
 962  * possible)
 963  */
 964 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 965                       *root, struct btrfs_key *key, struct btrfs_path *p, int
 966                       ins_len, int cow)
 967 {
 968         struct extent_buffer *b;
 969         u64 bytenr;
 970         int slot;
 971         int ret;
 972         int level;
 973         int should_reada = p->reada;
 974         u8 lowest_level = 0;
 975
 976         lowest_level = p->lowest_level;
 977         WARN_ON(lowest_level && ins_len);
 978         WARN_ON(p->nodes[0] != NULL);
 979         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
 980 again:
 981         b = root->node;
 982         extent_buffer_get(b);
 983         while (b) {
 984                 level = btrfs_header_level(b);
 985                 if (cow) {
 986                         int wret;
 987                         wret = btrfs_cow_block(trans, root, b,
 988                                                p->nodes[level + 1],
 989                                                p->slots[level + 1],
 990                                                &b);
 991                         if (wret) {
 992                                 free_extent_buffer(b);
 993                                 return wret;
 994                         }
 995                 }
 996                 BUG_ON(!cow && ins_len);
 997                 if (level != btrfs_header_level(b))
 998                         WARN_ON(1);
 999                 level = btrfs_header_level(b);
1000                 p->nodes[level] = b;
1001                 ret = check_block(root, p, level);
1002                 if (ret)
1003                         return -1;
1004                 ret = bin_search(b, key, level, &slot);
1005                 if (level != 0) {
1006                         if (ret && slot > 0)
1007                                 slot -= 1;
1008                         p->slots[level] = slot;
1009                         if (ins_len > 0 && btrfs_header_nritems(b) >=
1010                             BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1011                                 int sret = split_node(trans, root, p, level);
1012                                 BUG_ON(sret > 0);
1013                                 if (sret)
1014                                         return sret;
1015                                 b = p->nodes[level];
1016                                 slot = p->slots[level];
1017                         } else if (ins_len < 0) {
1018                                 int sret = balance_level(trans, root, p,
1019                                                          level);
1020                                 if (sret)
1021                                         return sret;
1022                                 b = p->nodes[level];
1023                                 if (!b) {
1024                                         btrfs_release_path(NULL, p);
1025                                         goto again;
1026                                 }
1027                                 slot = p->slots[level];
1028                                 BUG_ON(btrfs_header_nritems(b) == 1);
1029                         }
1030                         /* this is only true while dropping a snapshot */
1031                         if (level == lowest_level)
1032                                 break;
1033                         bytenr = btrfs_node_blockptr(b, slot);
1034                         if (should_reada)
1035                                 reada_for_search(root, p, level, slot);
1036                         b = read_tree_block(root, bytenr,
1037                                             btrfs_level_size(root, level - 1));
1038                 } else {
1039                         p->slots[level] = slot;
1040                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1041                             sizeof(struct btrfs_item) + ins_len) {
1042                                 int sret = split_leaf(trans, root, key,
1043                                                       p, ins_len);
1044                                 BUG_ON(sret > 0);
1045                                 if (sret)
1046                                         return sret;
1047                         }
1048                         return ret;
1049                 }
1050         }
1051         return 1;
1052 }
1053
1054 /*
1055  * adjust the pointers going up the tree, starting at level
1056  * making sure the right key of each node is points to 'key'.
1057  * This is used after shifting pointers to the left, so it stops
1058  * fixing up pointers when a given leaf/node is not in slot 0 of the
1059  * higher levels
1060  *
1061  * If this fails to write a tree block, it returns -1, but continues
1062  * fixing up the blocks in ram so the tree is consistent.
1063  */
1064 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1065                           struct btrfs_root *root, struct btrfs_path *path,
1066                           struct btrfs_disk_key *key, int level)
1067 {
1068         int i;
1069         int ret = 0;
1070         struct extent_buffer *t;
1071
1072         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1073                 int tslot = path->slots[i];
1074                 if (!path->nodes[i])
1075                         break;
1076                 t = path->nodes[i];
1077                 btrfs_set_node_key(t, key, tslot);
1078                 btrfs_mark_buffer_dirty(path->nodes[i]);
1079                 if (tslot != 0)
1080                         break;
1081         }
1082         return ret;
1083 }
1084
1085 /*
1086  * try to push data from one node into the next node left in the
1087  * tree.
1088  *
1089  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1090  * error, and > 0 if there was no room in the left hand block.
1091  */
1092 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
1093                           *root, struct extent_buffer *dst,
1094                           struct extent_buffer *src)
1095 {
1096         int push_items = 0;
1097         int src_nritems;
1098         int dst_nritems;
1099         int ret = 0;
1100
1101         src_nritems = btrfs_header_nritems(src);
1102         dst_nritems = btrfs_header_nritems(dst);
1103         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1104
1105         if (push_items <= 0) {
1106                 return 1;
1107         }
1108
1109         if (src_nritems < push_items)
1110                 push_items = src_nritems;
1111
1112         copy_extent_buffer(dst, src,
1113                            btrfs_node_key_ptr_offset(dst_nritems),
1114                            btrfs_node_key_ptr_offset(0),
1115                            push_items * sizeof(struct btrfs_key_ptr));
1116
1117         if (push_items < src_nritems) {
1118                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1119                                       btrfs_node_key_ptr_offset(push_items),
1120                                       (src_nritems - push_items) *
1121                                       sizeof(struct btrfs_key_ptr));
1122         }
1123         btrfs_set_header_nritems(src, src_nritems - push_items);
1124         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1125         btrfs_mark_buffer_dirty(src);
1126         btrfs_mark_buffer_dirty(dst);
1127         return ret;
1128 }
1129
1130 /*
1131  * try to push data from one node into the next node right in the
1132  * tree.
1133  *
1134  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1135  * error, and > 0 if there was no room in the right hand block.
1136  *
1137  * this will  only push up to 1/2 the contents of the left node over
1138  */
1139 static int balance_node_right(struct btrfs_trans_handle *trans,
1140                               struct btrfs_root *root,
1141                               struct extent_buffer *dst,
1142                               struct extent_buffer *src)
1143 {
1144         int push_items = 0;
1145         int max_push;
1146         int src_nritems;
1147         int dst_nritems;
1148         int ret = 0;
1149
1150         src_nritems = btrfs_header_nritems(src);
1151         dst_nritems = btrfs_header_nritems(dst);
1152         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1153         if (push_items <= 0)
1154                 return 1;
1155
1156         max_push = src_nritems / 2 + 1;
1157         /* don't try to empty the node */
1158         if (max_push >= src_nritems)
1159                 return 1;
1160
1161         if (max_push < push_items)
1162                 push_items = max_push;
1163
1164         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1165                                       btrfs_node_key_ptr_offset(0),
1166                                       (dst_nritems) *
1167                                       sizeof(struct btrfs_key_ptr));
1168
1169         copy_extent_buffer(dst, src,
1170                            btrfs_node_key_ptr_offset(0),
1171                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1172                            push_items * sizeof(struct btrfs_key_ptr));
1173
1174         btrfs_set_header_nritems(src, src_nritems - push_items);
1175         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1176
1177         btrfs_mark_buffer_dirty(src);
1178         btrfs_mark_buffer_dirty(dst);
1179         return ret;
1180 }
1181
1182 /*
1183  * helper function to insert a new root level in the tree.
1184  * A new node is allocated, and a single item is inserted to
1185  * point to the existing root
1186  *
1187  * returns zero on success or < 0 on failure.
1188  */
1189 static int insert_new_root(struct btrfs_trans_handle *trans,
1190                            struct btrfs_root *root,
1191                            struct btrfs_path *path, int level)
1192 {
1193         struct extent_buffer *lower;
1194         struct extent_buffer *c;
1195         struct btrfs_disk_key lower_key;
1196
1197         BUG_ON(path->nodes[level]);
1198         BUG_ON(path->nodes[level-1] != root->node);
1199
1200         c = btrfs_alloc_free_block(trans, root, root->nodesize,
1201                                    root->node->start, 0);
1202         if (IS_ERR(c))
1203                 return PTR_ERR(c);
1204         memset_extent_buffer(c, 0, 0, root->nodesize);
1205         btrfs_set_header_nritems(c, 1);
1206         btrfs_set_header_level(c, level);
1207         btrfs_set_header_bytenr(c, c->start);
1208         btrfs_set_header_generation(c, trans->transid);
1209         btrfs_set_header_owner(c, root->root_key.objectid);
1210         lower = path->nodes[level-1];
1211
1212         write_extent_buffer(c, root->fs_info->fsid,
1213                             (unsigned long)btrfs_header_fsid(c),
1214                             BTRFS_FSID_SIZE);
1215         if (level == 1)
1216                 btrfs_item_key(lower, &lower_key, 0);
1217         else
1218                 btrfs_node_key(lower, &lower_key, 0);
1219         btrfs_set_node_key(c, &lower_key, 0);
1220         btrfs_set_node_blockptr(c, 0, lower->start);
1221
1222         btrfs_mark_buffer_dirty(c);
1223
1224         /* the super has an extra ref to root->node */
1225         free_extent_buffer(root->node);
1226         root->node = c;
1227         extent_buffer_get(c);
1228         path->nodes[level] = c;
1229         path->slots[level] = 0;
1230         return 0;
1231 }
1232
1233 /*
1234  * worker function to insert a single pointer in a node.
1235  * the node should have enough room for the pointer already
1236  *
1237  * slot and level indicate where you want the key to go, and
1238  * blocknr is the block the key points to.
1239  *
1240  * returns zero on success and < 0 on any error
1241  */
1242 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1243                       *root, struct btrfs_path *path, struct btrfs_disk_key
1244                       *key, u64 bytenr, int slot, int level)
1245 {
1246         struct extent_buffer *lower;
1247         int nritems;
1248
1249         BUG_ON(!path->nodes[level]);
1250         lower = path->nodes[level];
1251         nritems = btrfs_header_nritems(lower);
1252         if (slot > nritems)
1253                 BUG();
1254         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1255                 BUG();
1256         if (slot != nritems) {
1257                 memmove_extent_buffer(lower,
1258                               btrfs_node_key_ptr_offset(slot + 1),
1259                               btrfs_node_key_ptr_offset(slot),
1260                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1261         }
1262         btrfs_set_node_key(lower, key, slot);
1263         btrfs_set_node_blockptr(lower, slot, bytenr);
1264         btrfs_set_header_nritems(lower, nritems + 1);
1265         btrfs_mark_buffer_dirty(lower);
1266         return 0;
1267 }
1268
1269 /*
1270  * split the node at the specified level in path in two.
1271  * The path is corrected to point to the appropriate node after the split
1272  *
1273  * Before splitting this tries to make some room in the node by pushing
1274  * left and right, if either one works, it returns right away.
1275  *
1276  * returns 0 on success and < 0 on failure
1277  */
1278 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1279                       *root, struct btrfs_path *path, int level)
1280 {
1281         struct extent_buffer *c;
1282         struct extent_buffer *split;
1283         struct btrfs_disk_key disk_key;
1284         int mid;
1285         int ret;
1286         int wret;
1287         u32 c_nritems;
1288
1289         c = path->nodes[level];
1290         if (c == root->node) {
1291                 /* trying to split the root, lets make a new one */
1292                 ret = insert_new_root(trans, root, path, level + 1);
1293                 if (ret)
1294                         return ret;
1295         } else {
1296                 ret = push_nodes_for_insert(trans, root, path, level);
1297                 c = path->nodes[level];
1298                 if (!ret && btrfs_header_nritems(c) <
1299                     BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
1300                         return 0;
1301                 if (ret < 0)
1302                         return ret;
1303         }
1304
1305         c_nritems = btrfs_header_nritems(c);
1306         split = btrfs_alloc_free_block(trans, root, root->nodesize,
1307                                        c->start, 0);
1308         if (IS_ERR(split))
1309                 return PTR_ERR(split);
1310
1311         btrfs_set_header_flags(split, btrfs_header_flags(c));
1312         btrfs_set_header_level(split, btrfs_header_level(c));
1313         btrfs_set_header_bytenr(split, split->start);
1314         btrfs_set_header_generation(split, trans->transid);
1315         btrfs_set_header_owner(split, root->root_key.objectid);
1316         write_extent_buffer(split, root->fs_info->fsid,
1317                             (unsigned long)btrfs_header_fsid(split),
1318                             BTRFS_FSID_SIZE);
1319
1320         mid = (c_nritems + 1) / 2;
1321
1322         copy_extent_buffer(split, c,
1323                            btrfs_node_key_ptr_offset(0),
1324                            btrfs_node_key_ptr_offset(mid),
1325                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1326         btrfs_set_header_nritems(split, c_nritems - mid);
1327         btrfs_set_header_nritems(c, mid);
1328         ret = 0;
1329
1330         btrfs_mark_buffer_dirty(c);
1331         btrfs_mark_buffer_dirty(split);
1332
1333         btrfs_node_key(split, &disk_key, 0);
1334         wret = insert_ptr(trans, root, path, &disk_key, split->start,
1335                           path->slots[level + 1] + 1,
1336                           level + 1);
1337         if (wret)
1338                 ret = wret;
1339
1340         if (path->slots[level] >= mid) {
1341                 path->slots[level] -= mid;
1342                 free_extent_buffer(c);
1343                 path->nodes[level] = split;
1344                 path->slots[level + 1] += 1;
1345         } else {
1346                 free_extent_buffer(split);
1347         }
1348         return ret;
1349 }
1350
1351 /*
1352  * how many bytes are required to store the items in a leaf.  start
1353  * and nr indicate which items in the leaf to check.  This totals up the
1354  * space used both by the item structs and the item data
1355  */
1356 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1357 {
1358         int data_len;
1359         int nritems = btrfs_header_nritems(l);
1360         int end = min(nritems, start + nr) - 1;
1361
1362         if (!nr)
1363                 return 0;
1364         data_len = btrfs_item_end_nr(l, start);
1365         data_len = data_len - btrfs_item_offset_nr(l, end);
1366         data_len += sizeof(struct btrfs_item) * nr;
1367         WARN_ON(data_len < 0);
1368         return data_len;
1369 }
1370
1371 /*
1372  * The space between the end of the leaf items and
1373  * the start of the leaf data.  IOW, how much room
1374  * the leaf has left for both items and data
1375  */
1376 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1377 {
1378         int nritems = btrfs_header_nritems(leaf);
1379         int ret;
1380         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1381         if (ret < 0) {
1382                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1383                        ret, BTRFS_LEAF_DATA_SIZE(root),
1384                        leaf_space_used(leaf, 0, nritems), nritems);
1385         }
1386         return ret;
1387 }
1388
1389 /*
1390  * push some data in the path leaf to the right, trying to free up at
1391  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1392  *
1393  * returns 1 if the push failed because the other node didn't have enough
1394  * room, 0 if everything worked out and < 0 if there were major errors.
1395  */
1396 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1397                            *root, struct btrfs_path *path, int data_size)
1398 {
1399         struct extent_buffer *left = path->nodes[0];
1400         struct extent_buffer *right;
1401         struct extent_buffer *upper;
1402         struct btrfs_disk_key disk_key;
1403         int slot;
1404         int i;
1405         int free_space;
1406         int push_space = 0;
1407         int push_items = 0;
1408         struct btrfs_item *item;
1409         u32 left_nritems;
1410         u32 right_nritems;
1411         u32 data_end;
1412         u32 this_item_size;
1413         int ret;
1414
1415         slot = path->slots[1];
1416         if (!path->nodes[1]) {
1417                 return 1;
1418         }
1419         upper = path->nodes[1];
1420         if (slot >= btrfs_header_nritems(upper) - 1)
1421                 return 1;
1422
1423         right = read_tree_block(root, btrfs_node_blockptr(upper, slot + 1),
1424                                 root->leafsize);
1425         free_space = btrfs_leaf_free_space(root, right);
1426         if (free_space < data_size + sizeof(struct btrfs_item)) {
1427                 free_extent_buffer(right);
1428                 return 1;
1429         }
1430
1431         /* cow and double check */
1432         ret = btrfs_cow_block(trans, root, right, upper,
1433                               slot + 1, &right);
1434         if (ret) {
1435                 free_extent_buffer(right);
1436                 return 1;
1437         }
1438         free_space = btrfs_leaf_free_space(root, right);
1439         if (free_space < data_size + sizeof(struct btrfs_item)) {
1440                 free_extent_buffer(right);
1441                 return 1;
1442         }
1443
1444         left_nritems = btrfs_header_nritems(left);
1445         if (left_nritems == 0) {
1446                 free_extent_buffer(right);
1447                 return 1;
1448         }
1449
1450         for (i = left_nritems - 1; i >= 1; i--) {
1451                 item = btrfs_item_nr(left, i);
1452
1453                 if (path->slots[0] == i)
1454                         push_space += data_size + sizeof(*item);
1455
1456                 if (!left->map_token) {
1457                         map_extent_buffer(left, (unsigned long)item,
1458                                         sizeof(struct btrfs_item),
1459                                         &left->map_token, &left->kaddr,
1460                                         &left->map_start, &left->map_len,
1461                                         KM_USER1);
1462                 }
1463
1464                 this_item_size = btrfs_item_size(left, item);
1465                 if (this_item_size + sizeof(*item) + push_space > free_space)
1466                         break;
1467                 push_items++;
1468                 push_space += this_item_size + sizeof(*item);
1469         }
1470         if (left->map_token) {
1471                 unmap_extent_buffer(left, left->map_token, KM_USER1);
1472                 left->map_token = NULL;
1473         }
1474
1475         if (push_items == 0) {
1476                 free_extent_buffer(right);
1477                 return 1;
1478         }
1479
1480         if (push_items == left_nritems)
1481                 WARN_ON(1);
1482
1483         /* push left to right */
1484         right_nritems = btrfs_header_nritems(right);
1485         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1486         push_space -= leaf_data_end(root, left);
1487
1488         /* make room in the right data area */
1489         data_end = leaf_data_end(root, right);
1490         memmove_extent_buffer(right,
1491                               btrfs_leaf_data(right) + data_end - push_space,
1492                               btrfs_leaf_data(right) + data_end,
1493                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1494
1495         /* copy from the left data area */
1496         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1497                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1498                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1499                      push_space);
1500
1501         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1502                               btrfs_item_nr_offset(0),
1503                               right_nritems * sizeof(struct btrfs_item));
1504
1505         /* copy the items from left to right */
1506         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1507                    btrfs_item_nr_offset(left_nritems - push_items),
1508                    push_items * sizeof(struct btrfs_item));
1509
1510         /* update the item pointers */
1511         right_nritems += push_items;
1512         btrfs_set_header_nritems(right, right_nritems);
1513         push_space = BTRFS_LEAF_DATA_SIZE(root);
1514
1515         for (i = 0; i < right_nritems; i++) {
1516                 item = btrfs_item_nr(right, i);
1517                 if (!right->map_token) {
1518                         map_extent_buffer(right, (unsigned long)item,
1519                                         sizeof(struct btrfs_item),
1520                                         &right->map_token, &right->kaddr,
1521                                         &right->map_start, &right->map_len,
1522                                         KM_USER1);
1523                 }
1524                 push_space -= btrfs_item_size(right, item);
1525                 btrfs_set_item_offset(right, item, push_space);
1526         }
1527
1528         if (right->map_token) {
1529                 unmap_extent_buffer(right, right->map_token, KM_USER1);
1530                 right->map_token = NULL;
1531         }
1532         left_nritems -= push_items;
1533         btrfs_set_header_nritems(left, left_nritems);
1534
1535         btrfs_mark_buffer_dirty(left);
1536         btrfs_mark_buffer_dirty(right);
1537
1538         btrfs_item_key(right, &disk_key, 0);
1539         btrfs_set_node_key(upper, &disk_key, slot + 1);
1540         btrfs_mark_buffer_dirty(upper);
1541
1542         /* then fixup the leaf pointer in the path */
1543         if (path->slots[0] >= left_nritems) {
1544                 path->slots[0] -= left_nritems;
1545                 free_extent_buffer(path->nodes[0]);
1546                 path->nodes[0] = right;
1547                 path->slots[1] += 1;
1548         } else {
1549                 free_extent_buffer(right);
1550         }
1551         return 0;
1552 }
1553 /*
1554  * push some data in the path leaf to the left, trying to free up at
1555  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1556  */
1557 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1558                           *root, struct btrfs_path *path, int data_size)
1559 {
1560         struct btrfs_disk_key disk_key;
1561         struct extent_buffer *right = path->nodes[0];
1562         struct extent_buffer *left;
1563         int slot;
1564         int i;
1565         int free_space;
1566         int push_space = 0;
1567         int push_items = 0;
1568         struct btrfs_item *item;
1569         u32 old_left_nritems;
1570         u32 right_nritems;
1571         int ret = 0;
1572         int wret;
1573         u32 this_item_size;
1574         u32 old_left_item_size;
1575
1576         slot = path->slots[1];
1577         if (slot == 0)
1578                 return 1;
1579         if (!path->nodes[1])
1580                 return 1;
1581
1582         left = read_tree_block(root, btrfs_node_blockptr(path->nodes[1],
1583                                slot - 1), root->leafsize);
1584         free_space = btrfs_leaf_free_space(root, left);
1585         if (free_space < data_size + sizeof(struct btrfs_item)) {
1586                 free_extent_buffer(left);
1587                 return 1;
1588         }
1589
1590         /* cow and double check */
1591         ret = btrfs_cow_block(trans, root, left,
1592                               path->nodes[1], slot - 1, &left);
1593         if (ret) {
1594                 /* we hit -ENOSPC, but it isn't fatal here */
1595                 free_extent_buffer(left);
1596                 return 1;
1597         }
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         right_nritems = btrfs_header_nritems(right);
1605         if (right_nritems == 0) {
1606                 free_extent_buffer(left);
1607                 return 1;
1608         }
1609
1610         for (i = 0; i < right_nritems - 1; i++) {
1611                 item = btrfs_item_nr(right, i);
1612                 if (!right->map_token) {
1613                         map_extent_buffer(right, (unsigned long)item,
1614                                         sizeof(struct btrfs_item),
1615                                         &right->map_token, &right->kaddr,
1616                                         &right->map_start, &right->map_len,
1617                                         KM_USER1);
1618                 }
1619
1620                 if (path->slots[0] == i)
1621                         push_space += data_size + sizeof(*item);
1622
1623                 this_item_size = btrfs_item_size(right, item);
1624                 if (this_item_size + sizeof(*item) + push_space > free_space)
1625                         break;
1626
1627                 push_items++;
1628                 push_space += this_item_size + sizeof(*item);
1629         }
1630
1631         if (right->map_token) {
1632                 unmap_extent_buffer(right, right->map_token, KM_USER1);
1633                 right->map_token = NULL;
1634         }
1635
1636         if (push_items == 0) {
1637                 free_extent_buffer(left);
1638                 return 1;
1639         }
1640         if (push_items == btrfs_header_nritems(right))
1641                 WARN_ON(1);
1642
1643         /* push data from right to left */
1644         copy_extent_buffer(left, right,
1645                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1646                            btrfs_item_nr_offset(0),
1647                            push_items * sizeof(struct btrfs_item));
1648
1649         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1650                      btrfs_item_offset_nr(right, push_items -1);
1651
1652         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1653                      leaf_data_end(root, left) - push_space,
1654                      btrfs_leaf_data(right) +
1655                      btrfs_item_offset_nr(right, push_items - 1),
1656                      push_space);
1657         old_left_nritems = btrfs_header_nritems(left);
1658         BUG_ON(old_left_nritems < 0);
1659
1660         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
1661         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1662                 u32 ioff;
1663
1664                 item = btrfs_item_nr(left, i);
1665                 if (!left->map_token) {
1666                         map_extent_buffer(left, (unsigned long)item,
1667                                         sizeof(struct btrfs_item),
1668                                         &left->map_token, &left->kaddr,
1669                                         &left->map_start, &left->map_len,
1670                                         KM_USER1);
1671                 }
1672
1673                 ioff = btrfs_item_offset(left, item);
1674                 btrfs_set_item_offset(left, item,
1675                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
1676         }
1677         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1678         if (left->map_token) {
1679                 unmap_extent_buffer(left, left->map_token, KM_USER1);
1680                 left->map_token = NULL;
1681         }
1682
1683         /* fixup right node */
1684         push_space = btrfs_item_offset_nr(right, push_items - 1) -
1685                                           leaf_data_end(root, right);
1686         memmove_extent_buffer(right, btrfs_leaf_data(right) +
1687                               BTRFS_LEAF_DATA_SIZE(root) - push_space,
1688                               btrfs_leaf_data(right) +
1689                               leaf_data_end(root, right), push_space);
1690
1691         memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1692                               btrfs_item_nr_offset(push_items),
1693                              (btrfs_header_nritems(right) - push_items) *
1694                              sizeof(struct btrfs_item));
1695
1696         right_nritems = btrfs_header_nritems(right) - push_items;
1697         btrfs_set_header_nritems(right, right_nritems);
1698         push_space = BTRFS_LEAF_DATA_SIZE(root);
1699
1700         for (i = 0; i < right_nritems; i++) {
1701                 item = btrfs_item_nr(right, i);
1702
1703                 if (!right->map_token) {
1704                         map_extent_buffer(right, (unsigned long)item,
1705                                         sizeof(struct btrfs_item),
1706                                         &right->map_token, &right->kaddr,
1707                                         &right->map_start, &right->map_len,
1708                                         KM_USER1);
1709                 }
1710
1711                 push_space = push_space - btrfs_item_size(right, item);
1712                 btrfs_set_item_offset(right, item, push_space);
1713         }
1714         if (right->map_token) {
1715                 unmap_extent_buffer(right, right->map_token, KM_USER1);
1716                 right->map_token = NULL;
1717         }
1718
1719         btrfs_mark_buffer_dirty(left);
1720         btrfs_mark_buffer_dirty(right);
1721
1722         btrfs_item_key(right, &disk_key, 0);
1723         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1724         if (wret)
1725                 ret = wret;
1726
1727         /* then fixup the leaf pointer in the path */
1728         if (path->slots[0] < push_items) {
1729                 path->slots[0] += old_left_nritems;
1730                 free_extent_buffer(path->nodes[0]);
1731                 path->nodes[0] = left;
1732                 path->slots[1] -= 1;
1733         } else {
1734                 free_extent_buffer(left);
1735                 path->slots[0] -= push_items;
1736         }
1737         BUG_ON(path->slots[0] < 0);
1738         return ret;
1739 }
1740
1741 /*
1742  * split the path's leaf in two, making sure there is at least data_size
1743  * available for the resulting leaf level of the path.
1744  *
1745  * returns 0 if all went well and < 0 on failure.
1746  */
1747 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1748                       *root, struct btrfs_key *ins_key,
1749                       struct btrfs_path *path, int data_size)
1750 {
1751         struct extent_buffer *l;
1752         u32 nritems;
1753         int mid;
1754         int slot;
1755         struct extent_buffer *right;
1756         int space_needed = data_size + sizeof(struct btrfs_item);
1757         int data_copy_size;
1758         int rt_data_off;
1759         int i;
1760         int ret = 0;
1761         int wret;
1762         int double_split = 0;
1763         struct btrfs_disk_key disk_key;
1764
1765         /* first try to make some room by pushing left and right */
1766         wret = push_leaf_left(trans, root, path, data_size);
1767         if (wret < 0) {
1768                 return wret;
1769         }
1770         if (wret) {
1771                 wret = push_leaf_right(trans, root, path, data_size);
1772                 if (wret < 0)
1773                         return wret;
1774         }
1775         l = path->nodes[0];
1776
1777         /* did the pushes work? */
1778         if (btrfs_leaf_free_space(root, l) >=
1779             sizeof(struct btrfs_item) + data_size) {
1780                 return 0;
1781         }
1782
1783         if (!path->nodes[1]) {
1784                 ret = insert_new_root(trans, root, path, 1);
1785                 if (ret)
1786                         return ret;
1787         }
1788         slot = path->slots[0];
1789         nritems = btrfs_header_nritems(l);
1790         mid = (nritems + 1)/ 2;
1791
1792         right = btrfs_alloc_free_block(trans, root, root->leafsize,
1793                                        l->start, 0);
1794         if (IS_ERR(right))
1795                 return PTR_ERR(right);
1796
1797         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1798         btrfs_set_header_bytenr(right, right->start);
1799         btrfs_set_header_generation(right, trans->transid);
1800         btrfs_set_header_owner(right, root->root_key.objectid);
1801         btrfs_set_header_level(right, 0);
1802         write_extent_buffer(right, root->fs_info->fsid,
1803                             (unsigned long)btrfs_header_fsid(right),
1804                             BTRFS_FSID_SIZE);
1805
1806         if (mid <= slot) {
1807                 if (nritems == 1 ||
1808                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1809                         BTRFS_LEAF_DATA_SIZE(root)) {
1810                         if (slot >= nritems) {
1811                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1812                                 btrfs_set_header_nritems(right, 0);
1813                                 wret = insert_ptr(trans, root, path,
1814                                                   &disk_key, right->start,
1815                                                   path->slots[1] + 1, 1);
1816                                 if (wret)
1817                                         ret = wret;
1818                                 free_extent_buffer(path->nodes[0]);
1819                                 path->nodes[0] = right;
1820                                 path->slots[0] = 0;
1821                                 path->slots[1] += 1;
1822                                 return ret;
1823                         }
1824                         mid = slot;
1825                         if (mid != nritems &&
1826                             leaf_space_used(l, mid, nritems - mid) +
1827                             space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1828                                 double_split = 1;
1829                         }
1830                 }
1831         } else {
1832                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1833                         BTRFS_LEAF_DATA_SIZE(root)) {
1834                         if (slot == 0) {
1835                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1836                                 btrfs_set_header_nritems(right, 0);
1837                                 wret = insert_ptr(trans, root, path,
1838                                                   &disk_key,
1839                                                   right->start,
1840                                                   path->slots[1], 1);
1841                                 if (wret)
1842                                         ret = wret;
1843                                 free_extent_buffer(path->nodes[0]);
1844                                 path->nodes[0] = right;
1845                                 path->slots[0] = 0;
1846                                 if (path->slots[1] == 0) {
1847                                         wret = fixup_low_keys(trans, root,
1848                                                    path, &disk_key, 1);
1849                                         if (wret)
1850                                                 ret = wret;
1851                                 }
1852                                 return ret;
1853                         }
1854                         mid = slot;
1855                         double_split = 1;
1856                 }
1857         }
1858         nritems = nritems - mid;
1859         btrfs_set_header_nritems(right, nritems);
1860         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
1861
1862         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
1863                            btrfs_item_nr_offset(mid),
1864                            nritems * sizeof(struct btrfs_item));
1865
1866         copy_extent_buffer(right, l,
1867                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1868                      data_copy_size, btrfs_leaf_data(l) +
1869                      leaf_data_end(root, l), data_copy_size);
1870
1871         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1872                       btrfs_item_end_nr(l, mid);
1873
1874         for (i = 0; i < nritems; i++) {
1875                 struct btrfs_item *item = btrfs_item_nr(right, i);
1876                 u32 ioff;
1877
1878                 if (!right->map_token) {
1879                         map_extent_buffer(right, (unsigned long)item,
1880                                         sizeof(struct btrfs_item),
1881                                         &right->map_token, &right->kaddr,
1882                                         &right->map_start, &right->map_len,
1883                                         KM_USER1);
1884                 }
1885
1886                 ioff = btrfs_item_offset(right, item);
1887                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
1888         }
1889
1890         if (right->map_token) {
1891                 unmap_extent_buffer(right, right->map_token, KM_USER1);
1892                 right->map_token = NULL;
1893         }
1894
1895         btrfs_set_header_nritems(l, mid);
1896         ret = 0;
1897         btrfs_item_key(right, &disk_key, 0);
1898         wret = insert_ptr(trans, root, path, &disk_key, right->start,
1899                           path->slots[1] + 1, 1);
1900         if (wret)
1901                 ret = wret;
1902
1903         btrfs_mark_buffer_dirty(right);
1904         btrfs_mark_buffer_dirty(l);
1905         BUG_ON(path->slots[0] != slot);
1906
1907         if (mid <= slot) {
1908                 free_extent_buffer(path->nodes[0]);
1909                 path->nodes[0] = right;
1910                 path->slots[0] -= mid;
1911                 path->slots[1] += 1;
1912         } else
1913                 free_extent_buffer(right);
1914
1915         BUG_ON(path->slots[0] < 0);
1916
1917         if (!double_split) {
1918                 return ret;
1919         }
1920
1921         right = btrfs_alloc_free_block(trans, root, root->leafsize,
1922                                        l->start, 0);
1923         if (IS_ERR(right))
1924                 return PTR_ERR(right);
1925
1926         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1927         btrfs_set_header_bytenr(right, right->start);
1928         btrfs_set_header_generation(right, trans->transid);
1929         btrfs_set_header_owner(right, root->root_key.objectid);
1930         btrfs_set_header_level(right, 0);
1931         write_extent_buffer(right, root->fs_info->fsid,
1932                             (unsigned long)btrfs_header_fsid(right),
1933                             BTRFS_FSID_SIZE);
1934
1935         btrfs_cpu_key_to_disk(&disk_key, ins_key);
1936         btrfs_set_header_nritems(right, 0);
1937         wret = insert_ptr(trans, root, path,
1938                           &disk_key, right->start,
1939                           path->slots[1], 1);
1940         if (wret)
1941                 ret = wret;
1942         if (path->slots[1] == 0) {
1943                 wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1944                 if (wret)
1945                         ret = wret;
1946         }
1947         free_extent_buffer(path->nodes[0]);
1948         path->nodes[0] = right;
1949         path->slots[0] = 0;
1950         return ret;
1951 }
1952
1953 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
1954                         struct btrfs_root *root,
1955                         struct btrfs_path *path,
1956                         u32 new_size)
1957 {
1958         int ret = 0;
1959         int slot;
1960         int slot_orig;
1961         struct extent_buffer *leaf;
1962         struct btrfs_item *item;
1963         u32 nritems;
1964         unsigned int data_end;
1965         unsigned int old_data_start;
1966         unsigned int old_size;
1967         unsigned int size_diff;
1968         int i;
1969
1970         slot_orig = path->slots[0];
1971         leaf = path->nodes[0];
1972
1973         nritems = btrfs_header_nritems(leaf);
1974         data_end = leaf_data_end(root, leaf);
1975
1976         slot = path->slots[0];
1977         old_data_start = btrfs_item_offset_nr(leaf, slot);
1978         old_size = btrfs_item_size_nr(leaf, slot);
1979         BUG_ON(old_size <= new_size);
1980         size_diff = old_size - new_size;
1981
1982         BUG_ON(slot < 0);
1983         BUG_ON(slot >= nritems);
1984
1985         /*
1986          * item0..itemN ... dataN.offset..dataN.size .. data0.size
1987          */
1988         /* first correct the data pointers */
1989         for (i = slot; i < nritems; i++) {
1990                 u32 ioff;
1991                 item = btrfs_item_nr(leaf, i);
1992
1993                 if (!leaf->map_token) {
1994                         map_extent_buffer(leaf, (unsigned long)item,
1995                                         sizeof(struct btrfs_item),
1996                                         &leaf->map_token, &leaf->kaddr,
1997                                         &leaf->map_start, &leaf->map_len,
1998                                         KM_USER1);
1999                 }
2000
2001                 ioff = btrfs_item_offset(leaf, item);
2002                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2003         }
2004
2005         if (leaf->map_token) {
2006                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2007                 leaf->map_token = NULL;
2008         }
2009
2010         /* shift the data */
2011         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2012                       data_end + size_diff, btrfs_leaf_data(leaf) +
2013                       data_end, old_data_start + new_size - data_end);
2014
2015         item = btrfs_item_nr(leaf, slot);
2016         btrfs_set_item_size(leaf, item, new_size);
2017         btrfs_mark_buffer_dirty(leaf);
2018
2019         ret = 0;
2020         if (btrfs_leaf_free_space(root, leaf) < 0) {
2021                 btrfs_print_leaf(root, leaf);
2022                 BUG();
2023         }
2024         return ret;
2025 }
2026
2027 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2028                       struct btrfs_root *root, struct btrfs_path *path,
2029                       u32 data_size)
2030 {
2031         int ret = 0;
2032         int slot;
2033         int slot_orig;
2034         struct extent_buffer *leaf;
2035         struct btrfs_item *item;
2036         u32 nritems;
2037         unsigned int data_end;
2038         unsigned int old_data;
2039         unsigned int old_size;
2040         int i;
2041
2042         slot_orig = path->slots[0];
2043         leaf = path->nodes[0];
2044
2045         nritems = btrfs_header_nritems(leaf);
2046         data_end = leaf_data_end(root, leaf);
2047
2048         if (btrfs_leaf_free_space(root, leaf) < data_size) {
2049                 btrfs_print_leaf(root, leaf);
2050                 BUG();
2051         }
2052         slot = path->slots[0];
2053         old_data = btrfs_item_end_nr(leaf, slot);
2054
2055         BUG_ON(slot < 0);
2056         if (slot >= nritems) {
2057                 btrfs_print_leaf(root, leaf);
2058                 printk("slot %d too large, nritems %d\n", slot, nritems);
2059                 BUG_ON(1);
2060         }
2061
2062         /*
2063          * item0..itemN ... dataN.offset..dataN.size .. data0.size
2064          */
2065         /* first correct the data pointers */
2066         for (i = slot; i < nritems; i++) {
2067                 u32 ioff;
2068                 item = btrfs_item_nr(leaf, i);
2069
2070                 if (!leaf->map_token) {
2071                         map_extent_buffer(leaf, (unsigned long)item,
2072                                         sizeof(struct btrfs_item),
2073                                         &leaf->map_token, &leaf->kaddr,
2074                                         &leaf->map_start, &leaf->map_len,
2075                                         KM_USER1);
2076                 }
2077                 ioff = btrfs_item_offset(leaf, item);
2078                 btrfs_set_item_offset(leaf, item, ioff - data_size);
2079         }
2080
2081         if (leaf->map_token) {
2082                 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2083                 leaf->map_token = NULL;
2084         }
2085
2086         /* shift the data */
2087         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2088                       data_end - data_size, btrfs_leaf_data(leaf) +
2089                       data_end, old_data - data_end);
2090
2091         data_end = old_data;
2092         old_size = btrfs_item_size_nr(leaf, slot);
2093         item = btrfs_item_nr(leaf, slot);
2094         btrfs_set_item_size(leaf, item, old_size + data_size);
2095         btrfs_mark_buffer_dirty(leaf);
2096
2097         ret = 0;
2098         if (btrfs_leaf_free_space(root, leaf) < 0) {
2099                 btrfs_print_leaf(root, leaf);
2100                 BUG();
2101         }
2102         return ret;
2103 }
2104
2105 /*
2106  * Given a key and some data, insert an item into the tree.
2107  * This does all the path init required, making room in the tree if needed.
2108  */
2109 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans,
2110                             struct btrfs_root *root,
2111                             struct btrfs_path *path,
2112                             struct btrfs_key *cpu_key, u32 data_size)
2113 {
2114         struct extent_buffer *leaf;
2115         struct btrfs_item *item;
2116         int ret = 0;
2117         int slot;
2118         int slot_orig;
2119         u32 nritems;
2120         unsigned int data_end;
2121         struct btrfs_disk_key disk_key;
2122
2123         btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2124
2125         /* create a root if there isn't one */
2126         if (!root->node)
2127                 BUG();
2128
2129         ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
2130         if (ret == 0) {
2131                 return -EEXIST;
2132         }
2133         if (ret < 0)
2134                 goto out;
2135
2136         slot_orig = path->slots[0];
2137         leaf = path->nodes[0];
2138
2139         nritems = btrfs_header_nritems(leaf);
2140         data_end = leaf_data_end(root, leaf);
2141
2142         if (btrfs_leaf_free_space(root, leaf) <
2143             sizeof(struct btrfs_item) + data_size) {
2144                 btrfs_print_leaf(root, leaf);
2145                 printk("not enough freespace need %u have %d\n",
2146                        data_size, btrfs_leaf_free_space(root, leaf));
2147                 BUG();
2148         }
2149
2150         slot = path->slots[0];
2151         BUG_ON(slot < 0);
2152
2153         if (slot != nritems) {
2154                 int i;
2155                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2156
2157                 if (old_data < data_end) {
2158                         btrfs_print_leaf(root, leaf);
2159                         printk("slot %d old_data %d data_end %d\n",
2160                                slot, old_data, data_end);
2161                         BUG_ON(1);
2162                 }
2163                 /*
2164                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2165                  */
2166                 /* first correct the data pointers */
2167                 WARN_ON(leaf->map_token);
2168                 for (i = slot; i < nritems; i++) {
2169                         u32 ioff;
2170
2171                         item = btrfs_item_nr(leaf, i);
2172                         if (!leaf->map_token) {
2173                                 map_extent_buffer(leaf, (unsigned long)item,
2174                                         sizeof(struct btrfs_item),
2175                                         &leaf->map_token, &leaf->kaddr,
2176                                         &leaf->map_start, &leaf->map_len,
2177                                         KM_USER1);
2178                         }
2179
2180                         ioff = btrfs_item_offset(leaf, item);
2181                         btrfs_set_item_offset(leaf, item, ioff - data_size);
2182                 }
2183                 if (leaf->map_token) {
2184                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2185                         leaf->map_token = NULL;
2186                 }
2187
2188                 /* shift the items */
2189                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
2190                               btrfs_item_nr_offset(slot),
2191                               (nritems - slot) * sizeof(struct btrfs_item));
2192
2193                 /* shift the data */
2194                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2195                               data_end - data_size, btrfs_leaf_data(leaf) +
2196                               data_end, old_data - data_end);
2197                 data_end = old_data;
2198         }
2199
2200         /* setup the item for the new data */
2201         btrfs_set_item_key(leaf, &disk_key, slot);
2202         item = btrfs_item_nr(leaf, slot);
2203         btrfs_set_item_offset(leaf, item, data_end - data_size);
2204         btrfs_set_item_size(leaf, item, data_size);
2205         btrfs_set_header_nritems(leaf, nritems + 1);
2206         btrfs_mark_buffer_dirty(leaf);
2207
2208         ret = 0;
2209         if (slot == 0)
2210                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2211
2212         if (btrfs_leaf_free_space(root, leaf) < 0) {
2213                 btrfs_print_leaf(root, leaf);
2214                 BUG();
2215         }
2216 out:
2217         return ret;
2218 }
2219
2220 /*
2221  * Given a key and some data, insert an item into the tree.
2222  * This does all the path init required, making room in the tree if needed.
2223  */
2224 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2225                       *root, struct btrfs_key *cpu_key, void *data, u32
2226                       data_size)
2227 {
2228         int ret = 0;
2229         struct btrfs_path *path;
2230         struct extent_buffer *leaf;
2231         unsigned long ptr;
2232
2233         path = btrfs_alloc_path();
2234         BUG_ON(!path);
2235         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2236         if (!ret) {
2237                 leaf = path->nodes[0];
2238                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2239                 write_extent_buffer(leaf, data, ptr, data_size);
2240                 btrfs_mark_buffer_dirty(leaf);
2241         }
2242         btrfs_free_path(path);
2243         return ret;
2244 }
2245
2246 /*
2247  * delete the pointer from a given node.
2248  *
2249  * If the delete empties a node, the node is removed from the tree,
2250  * continuing all the way the root if required.  The root is converted into
2251  * a leaf if all the nodes are emptied.
2252  */
2253 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2254                    struct btrfs_path *path, int level, int slot)
2255 {
2256         struct extent_buffer *parent = path->nodes[level];
2257         u32 nritems;
2258         int ret = 0;
2259         int wret;
2260
2261         nritems = btrfs_header_nritems(parent);
2262         if (slot != nritems -1) {
2263                 memmove_extent_buffer(parent,
2264                               btrfs_node_key_ptr_offset(slot),
2265                               btrfs_node_key_ptr_offset(slot + 1),
2266                               sizeof(struct btrfs_key_ptr) *
2267                               (nritems - slot - 1));
2268         }
2269         nritems--;
2270         btrfs_set_header_nritems(parent, nritems);
2271         if (nritems == 0 && parent == root->node) {
2272                 BUG_ON(btrfs_header_level(root->node) != 1);
2273                 /* just turn the root into a leaf and break */
2274                 btrfs_set_header_level(root->node, 0);
2275         } else if (slot == 0) {
2276                 struct btrfs_disk_key disk_key;
2277
2278                 btrfs_node_key(parent, &disk_key, 0);
2279                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2280                 if (wret)
2281                         ret = wret;
2282         }
2283         btrfs_mark_buffer_dirty(parent);
2284         return ret;
2285 }
2286
2287 /*
2288  * delete the item at the leaf level in path.  If that empties
2289  * the leaf, remove it from the tree
2290  */
2291 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2292                    struct btrfs_path *path)
2293 {
2294         int slot;
2295         struct extent_buffer *leaf;
2296         struct btrfs_item *item;
2297         int doff;
2298         int dsize;
2299         int ret = 0;
2300         int wret;
2301         u32 nritems;
2302
2303         leaf = path->nodes[0];
2304         slot = path->slots[0];
2305         doff = btrfs_item_offset_nr(leaf, slot);
2306         dsize = btrfs_item_size_nr(leaf, slot);
2307         nritems = btrfs_header_nritems(leaf);
2308
2309         if (slot != nritems - 1) {
2310                 int i;
2311                 int data_end = leaf_data_end(root, leaf);
2312
2313                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2314                               data_end + dsize,
2315                               btrfs_leaf_data(leaf) + data_end,
2316                               doff - data_end);
2317
2318                 for (i = slot + 1; i < nritems; i++) {
2319                         u32 ioff;
2320
2321                         item = btrfs_item_nr(leaf, i);
2322                         if (!leaf->map_token) {
2323                                 map_extent_buffer(leaf, (unsigned long)item,
2324                                         sizeof(struct btrfs_item),
2325                                         &leaf->map_token, &leaf->kaddr,
2326                                         &leaf->map_start, &leaf->map_len,
2327                                         KM_USER1);
2328                         }
2329                         ioff = btrfs_item_offset(leaf, item);
2330                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2331                 }
2332
2333                 if (leaf->map_token) {
2334                         unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2335                         leaf->map_token = NULL;
2336                 }
2337
2338                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2339                               btrfs_item_nr_offset(slot + 1),
2340                               sizeof(struct btrfs_item) *
2341                               (nritems - slot - 1));
2342         }
2343         btrfs_set_header_nritems(leaf, nritems - 1);
2344         nritems--;
2345
2346         /* delete the leaf if we've emptied it */
2347         if (nritems == 0) {
2348                 if (leaf == root->node) {
2349                         btrfs_set_header_level(leaf, 0);
2350                 } else {
2351                         clean_tree_block(trans, root, leaf);
2352                         wait_on_tree_block_writeback(root, leaf);
2353                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
2354                         if (wret)
2355                                 ret = wret;
2356                         wret = btrfs_free_extent(trans, root,
2357                                                  leaf->start, leaf->len, 1);
2358                         if (wret)
2359                                 ret = wret;
2360                 }
2361         } else {
2362                 int used = leaf_space_used(leaf, 0, nritems);
2363                 if (slot == 0) {
2364                         struct btrfs_disk_key disk_key;
2365
2366                         btrfs_item_key(leaf, &disk_key, 0);
2367                         wret = fixup_low_keys(trans, root, path,
2368                                               &disk_key, 1);
2369                         if (wret)
2370                                 ret = wret;
2371                 }
2372
2373                 /* delete the leaf if it is mostly empty */
2374                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
2375                         /* push_leaf_left fixes the path.
2376                          * make sure the path still points to our leaf
2377                          * for possible call to del_ptr below
2378                          */
2379                         slot = path->slots[1];
2380                         extent_buffer_get(leaf);
2381
2382                         wret = push_leaf_left(trans, root, path, 1);
2383                         if (wret < 0 && wret != -ENOSPC)
2384                                 ret = wret;
2385
2386                         if (path->nodes[0] == leaf &&
2387                             btrfs_header_nritems(leaf)) {
2388                                 wret = push_leaf_right(trans, root, path, 1);
2389                                 if (wret < 0 && wret != -ENOSPC)
2390                                         ret = wret;
2391                         }
2392
2393                         if (btrfs_header_nritems(leaf) == 0) {
2394                                 u64 bytenr = leaf->start;
2395                                 u32 blocksize = leaf->len;
2396
2397                                 clean_tree_block(trans, root, leaf);
2398                                 wait_on_tree_block_writeback(root, leaf);
2399
2400                                 wret = del_ptr(trans, root, path, 1, slot);
2401                                 if (wret)
2402                                         ret = wret;
2403
2404                                 free_extent_buffer(leaf);
2405                                 wret = btrfs_free_extent(trans, root, bytenr,
2406                                                          blocksize, 1);
2407                                 if (wret)
2408                                         ret = wret;
2409                         } else {
2410                                 btrfs_mark_buffer_dirty(leaf);
2411                                 free_extent_buffer(leaf);
2412                         }
2413                 } else {
2414                         btrfs_mark_buffer_dirty(leaf);
2415                 }
2416         }
2417         return ret;
2418 }
2419
2420 /*
2421  * walk up the tree as far as required to find the next leaf.
2422  * returns 0 if it found something or 1 if there are no greater leaves.
2423  * returns < 0 on io errors.
2424  */
2425 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2426 {
2427         int slot;
2428         int level = 1;
2429         u64 bytenr;
2430         struct extent_buffer *c;
2431         struct extent_buffer *next = NULL;
2432
2433         while(level < BTRFS_MAX_LEVEL) {
2434                 if (!path->nodes[level])
2435                         return 1;
2436
2437                 slot = path->slots[level] + 1;
2438                 c = path->nodes[level];
2439                 if (slot >= btrfs_header_nritems(c)) {
2440                         level++;
2441                         continue;
2442                 }
2443
2444                 bytenr = btrfs_node_blockptr(c, slot);
2445                 if (next)
2446                         free_extent_buffer(next);
2447
2448                 if (path->reada)
2449                         reada_for_search(root, path, level, slot);
2450
2451                 next = read_tree_block(root, bytenr,
2452                                        btrfs_level_size(root, level -1));
2453                 break;
2454         }
2455         path->slots[level] = slot;
2456         while(1) {
2457                 level--;
2458                 c = path->nodes[level];
2459                 free_extent_buffer(c);
2460                 path->nodes[level] = next;
2461                 path->slots[level] = 0;
2462                 if (!level)
2463                         break;
2464                 if (path->reada)
2465                         reada_for_search(root, path, level, 0);
2466                 next = read_tree_block(root, btrfs_node_blockptr(next, 0),
2467                                        btrfs_level_size(root, level - 1));
2468         }
2469         return 0;
2470 }