fs/btrfs/ctree.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/highmem.h>
  20 #include "ctree.h"
  21 #include "disk-io.h"
  22 #include "transaction.h"
  23 #include "print-tree.h"
  24
  25 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  26                       *root, struct btrfs_path *path, int level);
  27 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  28                       *root, struct btrfs_key *ins_key,
  29                       struct btrfs_path *path, int data_size);
  30 static int push_node_left(struct btrfs_trans_handle *trans,
  31                           struct btrfs_root *root, struct extent_buffer *dst,
  32                           struct extent_buffer *src);
  33 static int balance_node_right(struct btrfs_trans_handle *trans,
  34                               struct btrfs_root *root,
  35                               struct extent_buffer *dst_buf,
  36                               struct extent_buffer *src_buf);
  37 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  38                    struct btrfs_path *path, int level, int slot);
  39
  40 inline void btrfs_init_path(struct btrfs_path *p)
  41 {
  42         memset(p, 0, sizeof(*p));
  43 }
  44
  45 struct btrfs_path *btrfs_alloc_path(void)
  46 {
  47         struct btrfs_path *path;
  48         path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
  49         if (path) {
  50                 btrfs_init_path(path);
  51                 path->reada = 1;
  52         }
  53         return path;
  54 }
  55
  56 void btrfs_free_path(struct btrfs_path *p)
  57 {
  58         btrfs_release_path(NULL, p);
  59         kmem_cache_free(btrfs_path_cachep, p);
  60 }
  61
  62 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
  63 {
  64         int i;
  65         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  66                 if (!p->nodes[i])
  67                         break;
  68                 free_extent_buffer(p->nodes[i]);
  69         }
  70         memset(p, 0, sizeof(*p));
  71 }
  72
  73 static int __btrfs_cow_block(struct btrfs_trans_handle *trans,
  74                              struct btrfs_root *root,
  75                              struct extent_buffer *buf,
  76                              struct extent_buffer *parent, int parent_slot,
  77                              struct extent_buffer **cow_ret,
  78                              u64 search_start, u64 empty_size)
  79 {
  80         struct extent_buffer *cow;
  81         int ret = 0;
  82         int different_trans = 0;
  83
  84         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
  85
  86         cow = btrfs_alloc_free_block(trans, root, search_start, empty_size);
  87         if (IS_ERR(cow))
  88                 return PTR_ERR(cow);
  89
  90         if (buf->len != root->sectorsize || cow->len != root->sectorsize)
  91                 WARN_ON(1);
  92
  93         copy_extent_buffer(cow, buf, 0, 0, cow->len);
  94         btrfs_set_header_blocknr(cow, extent_buffer_blocknr(cow));
  95         btrfs_set_header_generation(cow, trans->transid);
  96         btrfs_set_header_owner(cow, root->root_key.objectid);
  97
  98         WARN_ON(btrfs_header_generation(buf) > trans->transid);
  99         if (btrfs_header_generation(buf) != trans->transid) {
 100                 different_trans = 1;
 101                 ret = btrfs_inc_ref(trans, root, buf);
 102                 if (ret)
 103                         return ret;
 104         } else {
 105                 clean_tree_block(trans, root, buf);
 106         }
 107
 108         if (buf == root->node) {
 109                 root->node = cow;
 110                 extent_buffer_get(cow);
 111                 if (buf != root->commit_root) {
 112                         btrfs_free_extent(trans, root,
 113                                           extent_buffer_blocknr(buf), 1, 1);
 114                 }
 115                 free_extent_buffer(buf);
 116         } else {
 117                 btrfs_set_node_blockptr(parent, parent_slot,
 118                                         extent_buffer_blocknr(cow));
 119                 btrfs_mark_buffer_dirty(parent);
 120                 WARN_ON(btrfs_header_generation(parent) != trans->transid);
 121                 btrfs_free_extent(trans, root, extent_buffer_blocknr(buf),1,1);
 122         }
 123         free_extent_buffer(buf);
 124         btrfs_mark_buffer_dirty(cow);
 125         *cow_ret = cow;
 126         return 0;
 127 }
 128
 129 int btrfs_cow_block(struct btrfs_trans_handle *trans,
 130                     struct btrfs_root *root, struct extent_buffer *buf,
 131                     struct extent_buffer *parent, int parent_slot,
 132                     struct extent_buffer **cow_ret)
 133 {
 134         u64 search_start;
 135         if (trans->transaction != root->fs_info->running_transaction) {
 136                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 137                        root->fs_info->running_transaction->transid);
 138                 WARN_ON(1);
 139         }
 140         if (trans->transid != root->fs_info->generation) {
 141                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 142                        root->fs_info->generation);
 143                 WARN_ON(1);
 144         }
 145         if (btrfs_header_generation(buf) == trans->transid) {
 146                 *cow_ret = buf;
 147                 return 0;
 148         }
 149
 150         search_start = extent_buffer_blocknr(buf) & ~((u64)65535);
 151         return __btrfs_cow_block(trans, root, buf, parent,
 152                                  parent_slot, cow_ret, search_start, 0);
 153 }
 154
 155 static int close_blocks(u64 blocknr, u64 other)
 156 {
 157         if (blocknr < other && other - blocknr < 8)
 158                 return 1;
 159         if (blocknr > other && blocknr - other < 8)
 160                 return 1;
 161         return 0;
 162 }
 163
 164 #if 0
 165 static int should_defrag_leaf(struct extent_buffer *eb)
 166 {
 167         return 0;
 168         struct btrfs_leaf *leaf = btrfs_buffer_leaf(eb);
 169         struct btrfs_disk_key *key;
 170         u32 nritems;
 171
 172         if (buffer_defrag(bh))
 173                 return 1;
 174
 175         nritems = btrfs_header_nritems(&leaf->header);
 176         if (nritems == 0)
 177                 return 0;
 178
 179         key = &leaf->items[0].key;
 180         if (btrfs_disk_key_type(key) == BTRFS_DIR_ITEM_KEY)
 181                 return 1;
 182
 183         key = &leaf->items[nritems-1].key;
 184         if (btrfs_disk_key_type(key) == BTRFS_DIR_ITEM_KEY)
 185                 return 1;
 186         if (nritems > 4) {
 187                 key = &leaf->items[nritems/2].key;
 188                 if (btrfs_disk_key_type(key) == BTRFS_DIR_ITEM_KEY)
 189                         return 1;
 190         }
 191         return 0;
 192 }
 193 #endif
 194
 195 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 196                        struct btrfs_root *root, struct extent_buffer *parent,
 197                        int cache_only, u64 *last_ret)
 198 {
 199         return 0;
 200 #if 0
 201         struct btrfs_node *parent_node;
 202         struct extent_buffer *cur_eb;
 203         struct extent_buffer *tmp_eb;
 204         u64 blocknr;
 205         u64 search_start = *last_ret;
 206         u64 last_block = 0;
 207         u64 other;
 208         u32 parent_nritems;
 209         int start_slot;
 210         int end_slot;
 211         int i;
 212         int err = 0;
 213         int parent_level;
 214
 215         if (trans->transaction != root->fs_info->running_transaction) {
 216                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 217                        root->fs_info->running_transaction->transid);
 218                 WARN_ON(1);
 219         }
 220         if (trans->transid != root->fs_info->generation) {
 221                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
 222                        root->fs_info->generation);
 223                 WARN_ON(1);
 224         }
 225         if (buffer_defrag_done(parent))
 226                 return 0;
 227
 228         parent_node = btrfs_buffer_node(parent);
 229         parent_nritems = btrfs_header_nritems(&parent_node->header);
 230         parent_level = btrfs_header_level(&parent_node->header);
 231
 232         start_slot = 0;
 233         end_slot = parent_nritems;
 234
 235         if (parent_nritems == 1)
 236                 return 0;
 237
 238         for (i = start_slot; i < end_slot; i++) {
 239                 int close = 1;
 240                 blocknr = btrfs_node_blockptr(parent_node, i);
 241                 if (last_block == 0)
 242                         last_block = blocknr;
 243                 if (i > 0) {
 244                         other = btrfs_node_blockptr(parent_node, i - 1);
 245                         close = close_blocks(blocknr, other);
 246                 }
 247                 if (close && i < end_slot - 1) {
 248                         other = btrfs_node_blockptr(parent_node, i + 1);
 249                         close = close_blocks(blocknr, other);
 250                 }
 251                 if (close) {
 252                         last_block = blocknr;
 253                         continue;
 254                 }
 255
 256                 cur_bh = btrfs_find_tree_block(root, blocknr);
 257                 if (!cur_bh || !buffer_uptodate(cur_bh) ||
 258                     buffer_locked(cur_bh) ||
 259                     (parent_level != 1 && !buffer_defrag(cur_bh)) ||
 260                     (parent_level == 1 && !should_defrag_leaf(cur_bh))) {
 261                         if (cache_only) {
 262                                 brelse(cur_bh);
 263                                 continue;
 264                         }
 265                         if (!cur_bh || !buffer_uptodate(cur_bh) ||
 266                             buffer_locked(cur_bh)) {
 267                                 brelse(cur_bh);
 268                                 cur_bh = read_tree_block(root, blocknr);
 269                         }
 270                 }
 271                 if (search_start == 0)
 272                         search_start = last_block & ~((u64)65535);
 273
 274                 err = __btrfs_cow_block(trans, root, cur_bh, parent, i,
 275                                         &tmp_bh, search_start,
 276                                         min(8, end_slot - i));
 277                 if (err) {
 278                         brelse(cur_bh);
 279                         break;
 280                 }
 281                 search_start = bh_blocknr(tmp_bh);
 282                 *last_ret = search_start;
 283                 if (parent_level == 1)
 284                         clear_buffer_defrag(tmp_bh);
 285                 set_buffer_defrag_done(tmp_bh);
 286                 brelse(tmp_bh);
 287         }
 288         return err;
 289 #endif
 290 }
 291
 292 /*
 293  * The leaf data grows from end-to-front in the node.
 294  * this returns the address of the start of the last item,
 295  * which is the stop of the leaf data stack
 296  */
 297 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 298                                          struct extent_buffer *leaf)
 299 {
 300         u32 nr = btrfs_header_nritems(leaf);
 301         if (nr == 0)
 302                 return BTRFS_LEAF_DATA_SIZE(root);
 303         return btrfs_item_offset_nr(leaf, nr - 1);
 304 }
 305
 306 /*
 307  * compare two keys in a memcmp fashion
 308  */
 309 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 310 {
 311         struct btrfs_key k1;
 312
 313         btrfs_disk_key_to_cpu(&k1, disk);
 314
 315         if (k1.objectid > k2->objectid)
 316                 return 1;
 317         if (k1.objectid < k2->objectid)
 318                 return -1;
 319         if (k1.type > k2->type)
 320                 return 1;
 321         if (k1.type < k2->type)
 322                 return -1;
 323         if (k1.offset > k2->offset)
 324                 return 1;
 325         if (k1.offset < k2->offset)
 326                 return -1;
 327         return 0;
 328 }
 329
 330 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 331                       int level)
 332 {
 333         struct extent_buffer *parent = NULL;
 334         struct extent_buffer *node = path->nodes[level];
 335         struct btrfs_disk_key parent_key;
 336         struct btrfs_disk_key node_key;
 337         int parent_slot;
 338         int slot;
 339         struct btrfs_key cpukey;
 340         u32 nritems = btrfs_header_nritems(node);
 341
 342         if (path->nodes[level + 1])
 343                 parent = path->nodes[level + 1];
 344
 345         slot = path->slots[level];
 346         BUG_ON(nritems == 0);
 347         if (parent) {
 348                 parent_slot = path->slots[level + 1];
 349                 btrfs_node_key(parent, &parent_key, parent_slot);
 350                 btrfs_node_key(node, &node_key, 0);
 351                 BUG_ON(memcmp(&parent_key, &node_key,
 352                               sizeof(struct btrfs_disk_key)));
 353                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 354                        btrfs_header_blocknr(node));
 355         }
 356         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 357         if (slot != 0) {
 358                 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
 359                 btrfs_node_key(node, &node_key, slot);
 360                 BUG_ON(comp_keys(&node_key, &cpukey) <= 0);
 361         }
 362         if (slot < nritems - 1) {
 363                 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
 364                 btrfs_node_key(node, &node_key, slot);
 365                 BUG_ON(comp_keys(&node_key, &cpukey) >= 0);
 366         }
 367         return 0;
 368 }
 369
 370 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 371                       int level)
 372 {
 373         struct extent_buffer *leaf = path->nodes[level];
 374         struct extent_buffer *parent = NULL;
 375         int parent_slot;
 376         struct btrfs_key cpukey;
 377         struct btrfs_disk_key parent_key;
 378         struct btrfs_disk_key leaf_key;
 379         int slot = path->slots[0];
 380
 381         u32 nritems = btrfs_header_nritems(leaf);
 382
 383         if (path->nodes[level + 1])
 384                 parent = path->nodes[level + 1];
 385
 386         if (nritems == 0)
 387                 return 0;
 388
 389         if (parent) {
 390                 parent_slot = path->slots[level + 1];
 391                 btrfs_node_key(parent, &parent_key, parent_slot);
 392                 btrfs_item_key(leaf, &leaf_key, 0);
 393
 394                 BUG_ON(memcmp(&parent_key, &leaf_key,
 395                        sizeof(struct btrfs_disk_key)));
 396                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 397                        btrfs_header_blocknr(leaf));
 398         }
 399 #if 0
 400         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 401                 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
 402                 btrfs_item_key(leaf, &leaf_key, i);
 403                 if (comp_keys(&leaf_key, &cpukey) >= 0) {
 404                         btrfs_print_leaf(root, leaf);
 405                         printk("slot %d offset bad key\n", i);
 406                         BUG_ON(1);
 407                 }
 408                 if (btrfs_item_offset_nr(leaf, i) !=
 409                         btrfs_item_end_nr(leaf, i + 1)) {
 410                         btrfs_print_leaf(root, leaf);
 411                         printk("slot %d offset bad\n", i);
 412                         BUG_ON(1);
 413                 }
 414                 if (i == 0) {
 415                         if (btrfs_item_offset_nr(leaf, i) +
 416                                btrfs_item_size_nr(leaf, i) !=
 417                                BTRFS_LEAF_DATA_SIZE(root)) {
 418                                 btrfs_print_leaf(root, leaf);
 419                                 printk("slot %d first offset bad\n", i);
 420                                 BUG_ON(1);
 421                         }
 422                 }
 423         }
 424         if (nritems > 0) {
 425                 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
 426                                 btrfs_print_leaf(root, leaf);
 427                                 printk("slot %d bad size \n", nritems - 1);
 428                                 BUG_ON(1);
 429                 }
 430         }
 431 #endif
 432         if (slot != 0 && slot < nritems - 1) {
 433                 btrfs_item_key(leaf, &leaf_key, slot);
 434                 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
 435                 if (comp_keys(&leaf_key, &cpukey) <= 0) {
 436                         btrfs_print_leaf(root, leaf);
 437                         printk("slot %d offset bad key\n", slot);
 438                         BUG_ON(1);
 439                 }
 440                 if (btrfs_item_offset_nr(leaf, slot - 1) !=
 441                        btrfs_item_end_nr(leaf, slot)) {
 442                         btrfs_print_leaf(root, leaf);
 443                         printk("slot %d offset bad\n", slot);
 444                         BUG_ON(1);
 445                 }
 446         }
 447         if (slot < nritems - 1) {
 448                 btrfs_item_key(leaf, &leaf_key, slot);
 449                 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
 450                 BUG_ON(comp_keys(&leaf_key, &cpukey) >= 0);
 451                 if (btrfs_item_offset_nr(leaf, slot) !=
 452                         btrfs_item_end_nr(leaf, slot + 1)) {
 453                         btrfs_print_leaf(root, leaf);
 454                         printk("slot %d offset bad\n", slot);
 455                         BUG_ON(1);
 456                 }
 457         }
 458         BUG_ON(btrfs_item_offset_nr(leaf, 0) +
 459                btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
 460         return 0;
 461 }
 462
 463 static int check_block(struct btrfs_root *root, struct btrfs_path *path,
 464                         int level)
 465 {
 466         struct extent_buffer *buf = path->nodes[level];
 467
 468         if (memcmp_extent_buffer(buf, root->fs_info->fsid,
 469                                  (unsigned long)btrfs_header_fsid(buf),
 470                                  BTRFS_FSID_SIZE)) {
 471                 printk("warning bad block %Lu\n", buf->start);
 472                 BUG();
 473         }
 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 }
 586
 587 static int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root
 588                          *root, struct btrfs_path *path, int level)
 589 {
 590         struct extent_buffer *right = NULL;
 591         struct extent_buffer *mid;
 592         struct extent_buffer *left = NULL;
 593         struct extent_buffer *parent = NULL;
 594         int ret = 0;
 595         int wret;
 596         int pslot;
 597         int orig_slot = path->slots[level];
 598         int err_on_enospc = 0;
 599         u64 orig_ptr;
 600
 601         if (level == 0)
 602                 return 0;
 603
 604         mid = path->nodes[level];
 605         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 606
 607         if (level < BTRFS_MAX_LEVEL - 1)
 608                 parent = path->nodes[level + 1];
 609         pslot = path->slots[level + 1];
 610
 611         /*
 612          * deal with the case where there is only one pointer in the root
 613          * by promoting the node below to a root
 614          */
 615         if (!parent) {
 616                 struct extent_buffer *child;
 617                 u64 blocknr = extent_buffer_blocknr(mid);
 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                 /* once for the root ptr */
 632                 free_extent_buffer(mid);
 633                 return btrfs_free_extent(trans, root, blocknr, 1, 1);
 634         }
 635         if (btrfs_header_nritems(mid) >
 636             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 637                 return 0;
 638
 639         if (btrfs_header_nritems(mid) < 2)
 640                 err_on_enospc = 1;
 641
 642         left = read_node_slot(root, parent, pslot - 1);
 643         if (left) {
 644                 wret = btrfs_cow_block(trans, root, left,
 645                                        parent, pslot - 1, &left);
 646                 if (wret) {
 647                         ret = wret;
 648                         goto enospc;
 649                 }
 650         }
 651         right = read_node_slot(root, parent, pslot + 1);
 652         if (right) {
 653                 wret = btrfs_cow_block(trans, root, right,
 654                                        parent, pslot + 1, &right);
 655                 if (wret) {
 656                         ret = wret;
 657                         goto enospc;
 658                 }
 659         }
 660
 661         /* first, try to make some room in the middle buffer */
 662         if (left) {
 663                 orig_slot += btrfs_header_nritems(left);
 664                 wret = push_node_left(trans, root, left, mid);
 665                 if (wret < 0)
 666                         ret = wret;
 667                 if (btrfs_header_nritems(mid) < 2)
 668                         err_on_enospc = 1;
 669         }
 670
 671         /*
 672          * then try to empty the right most buffer into the middle
 673          */
 674         if (right) {
 675                 wret = push_node_left(trans, root, mid, right);
 676                 if (wret < 0 && wret != -ENOSPC)
 677                         ret = wret;
 678                 if (btrfs_header_nritems(right) == 0) {
 679                         u64 blocknr = extent_buffer_blocknr(right);
 680                         clean_tree_block(trans, root, right);
 681                         wait_on_tree_block_writeback(root, right);
 682                         free_extent_buffer(right);
 683                         right = NULL;
 684                         wret = del_ptr(trans, root, path, level + 1, pslot +
 685                                        1);
 686                         if (wret)
 687                                 ret = wret;
 688                         wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
 689                         if (wret)
 690                                 ret = wret;
 691                 } else {
 692                         struct btrfs_disk_key right_key;
 693                         btrfs_node_key(right, &right_key, 0);
 694                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 695                         btrfs_mark_buffer_dirty(parent);
 696                 }
 697         }
 698         if (btrfs_header_nritems(mid) == 1) {
 699                 /*
 700                  * we're not allowed to leave a node with one item in the
 701                  * tree during a delete.  A deletion from lower in the tree
 702                  * could try to delete the only pointer in this node.
 703                  * So, pull some keys from the left.
 704                  * There has to be a left pointer at this point because
 705                  * otherwise we would have pulled some pointers from the
 706                  * right
 707                  */
 708                 BUG_ON(!left);
 709                 wret = balance_node_right(trans, root, mid, left);
 710                 if (wret < 0) {
 711                         ret = wret;
 712                         goto enospc;
 713                 }
 714                 BUG_ON(wret == 1);
 715         }
 716         if (btrfs_header_nritems(mid) == 0) {
 717                 /* we've managed to empty the middle node, drop it */
 718                 u64 blocknr = extent_buffer_blocknr(mid);
 719                 clean_tree_block(trans, root, mid);
 720                 wait_on_tree_block_writeback(root, mid);
 721                 free_extent_buffer(mid);
 722                 mid = NULL;
 723                 wret = del_ptr(trans, root, path, level + 1, pslot);
 724                 if (wret)
 725                         ret = wret;
 726                 wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
 727                 if (wret)
 728                         ret = wret;
 729         } else {
 730                 /* update the parent key to reflect our changes */
 731                 struct btrfs_disk_key mid_key;
 732                 btrfs_node_key(mid, &mid_key, 0);
 733                 btrfs_set_node_key(parent, &mid_key, pslot);
 734                 btrfs_mark_buffer_dirty(parent);
 735         }
 736
 737         /* update the path */
 738         if (left) {
 739                 if (btrfs_header_nritems(left) > orig_slot) {
 740                         extent_buffer_get(left);
 741                         path->nodes[level] = left;
 742                         path->slots[level + 1] -= 1;
 743                         path->slots[level] = orig_slot;
 744                         if (mid)
 745                                 free_extent_buffer(mid);
 746                 } else {
 747                         orig_slot -= btrfs_header_nritems(left);
 748                         path->slots[level] = orig_slot;
 749                 }
 750         }
 751         /* double check we haven't messed things up */
 752         check_block(root, path, level);
 753         if (orig_ptr !=
 754             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
 755                 BUG();
 756 enospc:
 757         if (right)
 758                 free_extent_buffer(right);
 759         if (left)
 760                 free_extent_buffer(left);
 761         return ret;
 762 }
 763
 764 /* returns zero if the push worked, non-zero otherwise */
 765 static int push_nodes_for_insert(struct btrfs_trans_handle *trans,
 766                                 struct btrfs_root *root,
 767                                 struct btrfs_path *path, int level)
 768 {
 769         struct extent_buffer *right = NULL;
 770         struct extent_buffer *mid;
 771         struct extent_buffer *left = NULL;
 772         struct extent_buffer *parent = NULL;
 773         int ret = 0;
 774         int wret;
 775         int pslot;
 776         int orig_slot = path->slots[level];
 777         u64 orig_ptr;
 778
 779         if (level == 0)
 780                 return 1;
 781
 782         mid = path->nodes[level];
 783         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 784
 785         if (level < BTRFS_MAX_LEVEL - 1)
 786                 parent = path->nodes[level + 1];
 787         pslot = path->slots[level + 1];
 788
 789         if (!parent)
 790                 return 1;
 791
 792         left = read_node_slot(root, parent, pslot - 1);
 793
 794         /* first, try to make some room in the middle buffer */
 795         if (left) {
 796                 u32 left_nr;
 797                 left_nr = btrfs_header_nritems(left);
 798                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 799                         wret = 1;
 800                 } else {
 801                         ret = btrfs_cow_block(trans, root, left, parent,
 802                                               pslot - 1, &left);
 803                         if (ret)
 804                                 wret = 1;
 805                         else {
 806                                 wret = push_node_left(trans, root,
 807                                                       left, mid);
 808                         }
 809                 }
 810                 if (wret < 0)
 811                         ret = wret;
 812                 if (wret == 0) {
 813                         struct btrfs_disk_key disk_key;
 814                         orig_slot += left_nr;
 815                         btrfs_node_key(mid, &disk_key, 0);
 816                         btrfs_set_node_key(parent, &disk_key, pslot);
 817                         btrfs_mark_buffer_dirty(parent);
 818                         if (btrfs_header_nritems(left) > orig_slot) {
 819                                 path->nodes[level] = left;
 820                                 path->slots[level + 1] -= 1;
 821                                 path->slots[level] = orig_slot;
 822                                 free_extent_buffer(mid);
 823                         } else {
 824                                 orig_slot -=
 825                                         btrfs_header_nritems(left);
 826                                 path->slots[level] = orig_slot;
 827                                 free_extent_buffer(left);
 828                         }
 829                         check_node(root, path, level);
 830                         return 0;
 831                 }
 832                 free_extent_buffer(left);
 833         }
 834         right= read_node_slot(root, parent, pslot + 1);
 835
 836         /*
 837          * then try to empty the right most buffer into the middle
 838          */
 839         if (right) {
 840                 u32 right_nr;
 841                 right_nr = btrfs_header_nritems(right);
 842                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 843                         wret = 1;
 844                 } else {
 845                         ret = btrfs_cow_block(trans, root, right,
 846                                               parent, pslot + 1,
 847                                               &right);
 848                         if (ret)
 849                                 wret = 1;
 850                         else {
 851                                 wret = balance_node_right(trans, root,
 852                                                           right, mid);
 853                         }
 854                 }
 855                 if (wret < 0)
 856                         ret = wret;
 857                 if (wret == 0) {
 858                         struct btrfs_disk_key disk_key;
 859
 860                         btrfs_node_key(right, &disk_key, 0);
 861                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
 862                         btrfs_mark_buffer_dirty(parent);
 863
 864                         if (btrfs_header_nritems(mid) <= orig_slot) {
 865                                 path->nodes[level] = right;
 866                                 path->slots[level + 1] += 1;
 867                                 path->slots[level] = orig_slot -
 868                                         btrfs_header_nritems(mid);
 869                                 free_extent_buffer(mid);
 870                         } else {
 871                                 free_extent_buffer(right);
 872                         }
 873                         check_node(root, path, level);
 874                         return 0;
 875                 }
 876                 free_extent_buffer(right);
 877         }
 878         check_node(root, path, level);
 879         return 1;
 880 }
 881
 882 /*
 883  * readahead one full node of leaves
 884  */
 885 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
 886                              int level, int slot)
 887 {
 888         struct extent_buffer *node;
 889         int i;
 890         u32 nritems;
 891         u64 blocknr;
 892         u64 search;
 893         u64 cluster_start;
 894         int ret;
 895         int nread = 0;
 896         int direction = path->reada;
 897         struct radix_tree_root found;
 898         unsigned long gang[8];
 899         struct extent_buffer *eb;
 900
 901         if (level == 0)
 902                 return;
 903
 904         if (!path->nodes[level])
 905                 return;
 906
 907         node = path->nodes[level];
 908         search = btrfs_node_blockptr(node, slot);
 909         eb = btrfs_find_tree_block(root, search);
 910         if (eb) {
 911                 free_extent_buffer(eb);
 912                 return;
 913         }
 914
 915         init_bit_radix(&found);
 916         nritems = btrfs_header_nritems(node);
 917         for (i = slot; i < nritems; i++) {
 918                 blocknr = btrfs_node_blockptr(node, i);
 919                 set_radix_bit(&found, blocknr);
 920         }
 921         if (direction > 0) {
 922                 cluster_start = search - 4;
 923                 if (cluster_start > search)
 924                         cluster_start = 0;
 925         } else
 926                 cluster_start = search + 4;
 927         while(1) {
 928                 ret = find_first_radix_bit(&found, gang, 0, ARRAY_SIZE(gang));
 929                 if (!ret)
 930                         break;
 931                 for (i = 0; i < ret; i++) {
 932                         blocknr = gang[i];
 933                         clear_radix_bit(&found, blocknr);
 934                         if (path->reada == 1 && nread > 16)
 935                                 continue;
 936                         if (close_blocks(cluster_start, blocknr)) {
 937                                 readahead_tree_block(root, blocknr);
 938                                 nread++;
 939                                 cluster_start = blocknr;
 940                         }
 941                 }
 942         }
 943 }
 944 /*
 945  * look for key in the tree.  path is filled in with nodes along the way
 946  * if key is found, we return zero and you can find the item in the leaf
 947  * level of the path (level 0)
 948  *
 949  * If the key isn't found, the path points to the slot where it should
 950  * be inserted, and 1 is returned.  If there are other errors during the
 951  * search a negative error number is returned.
 952  *
 953  * if ins_len > 0, nodes and leaves will be split as we walk down the
 954  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
 955  * possible)
 956  */
 957 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 958                       *root, struct btrfs_key *key, struct btrfs_path *p, int
 959                       ins_len, int cow)
 960 {
 961         struct extent_buffer *b;
 962         u64 blocknr;
 963         int slot;
 964         int ret;
 965         int level;
 966         int should_reada = p->reada;
 967         u8 lowest_level = 0;
 968
 969         lowest_level = p->lowest_level;
 970         WARN_ON(lowest_level && ins_len);
 971         WARN_ON(p->nodes[0] != NULL);
 972         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
 973 again:
 974         b = root->node;
 975         extent_buffer_get(b);
 976         while (b) {
 977                 level = btrfs_header_level(b);
 978                 if (cow) {
 979                         int wret;
 980                         wret = btrfs_cow_block(trans, root, b,
 981                                                p->nodes[level + 1],
 982                                                p->slots[level + 1],
 983                                                &b);
 984                         if (wret) {
 985                                 free_extent_buffer(b);
 986                                 return wret;
 987                         }
 988                 }
 989                 BUG_ON(!cow && ins_len);
 990                 if (level != btrfs_header_level(b))
 991                         WARN_ON(1);
 992                 level = btrfs_header_level(b);
 993                 p->nodes[level] = b;
 994                 ret = check_block(root, p, level);
 995                 if (ret)
 996                         return -1;
 997                 ret = bin_search(b, key, level, &slot);
 998                 if (level != 0) {
 999                         if (ret && slot > 0)
1000                                 slot -= 1;
1001                         p->slots[level] = slot;
1002                         if (ins_len > 0 && btrfs_header_nritems(b) >=
1003                             BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1004                                 int sret = split_node(trans, root, p, level);
1005                                 BUG_ON(sret > 0);
1006                                 if (sret)
1007                                         return sret;
1008                                 b = p->nodes[level];
1009                                 slot = p->slots[level];
1010                         } else if (ins_len < 0) {
1011                                 int sret = balance_level(trans, root, p,
1012                                                          level);
1013                                 if (sret)
1014                                         return sret;
1015                                 b = p->nodes[level];
1016                                 if (!b)
1017                                         goto again;
1018                                 slot = p->slots[level];
1019                                 BUG_ON(btrfs_header_nritems(b) == 1);
1020                         }
1021                         /* this is only true while dropping a snapshot */
1022                         if (level == lowest_level)
1023                                 break;
1024                         blocknr = btrfs_node_blockptr(b, slot);
1025                         if (should_reada)
1026                                 reada_for_search(root, p, level, slot);
1027                         b = read_tree_block(root, btrfs_node_blockptr(b, slot));
1028                 } else {
1029                         p->slots[level] = slot;
1030                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1031                             sizeof(struct btrfs_item) + ins_len) {
1032                                 int sret = split_leaf(trans, root, key,
1033                                                       p, ins_len);
1034                                 BUG_ON(sret > 0);
1035                                 if (sret)
1036                                         return sret;
1037                         }
1038                         return ret;
1039                 }
1040         }
1041         return 1;
1042 }
1043
1044 /*
1045  * adjust the pointers going up the tree, starting at level
1046  * making sure the right key of each node is points to 'key'.
1047  * This is used after shifting pointers to the left, so it stops
1048  * fixing up pointers when a given leaf/node is not in slot 0 of the
1049  * higher levels
1050  *
1051  * If this fails to write a tree block, it returns -1, but continues
1052  * fixing up the blocks in ram so the tree is consistent.
1053  */
1054 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1055                           struct btrfs_root *root, struct btrfs_path *path,
1056                           struct btrfs_disk_key *key, int level)
1057 {
1058         int i;
1059         int ret = 0;
1060         struct extent_buffer *t;
1061
1062         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1063                 int tslot = path->slots[i];
1064                 if (!path->nodes[i])
1065                         break;
1066                 t = path->nodes[i];
1067                 btrfs_set_node_key(t, key, tslot);
1068                 btrfs_mark_buffer_dirty(path->nodes[i]);
1069                 if (tslot != 0)
1070                         break;
1071         }
1072         return ret;
1073 }
1074
1075 /*
1076  * try to push data from one node into the next node left in the
1077  * tree.
1078  *
1079  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1080  * error, and > 0 if there was no room in the left hand block.
1081  */
1082 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
1083                           *root, struct extent_buffer *dst,
1084                           struct extent_buffer *src)
1085 {
1086         int push_items = 0;
1087         int src_nritems;
1088         int dst_nritems;
1089         int ret = 0;
1090
1091         src_nritems = btrfs_header_nritems(src);
1092         dst_nritems = btrfs_header_nritems(dst);
1093         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1094
1095         if (push_items <= 0) {
1096                 return 1;
1097         }
1098
1099         if (src_nritems < push_items)
1100                 push_items = src_nritems;
1101
1102         copy_extent_buffer(dst, src,
1103                            btrfs_node_key_ptr_offset(dst_nritems),
1104                            btrfs_node_key_ptr_offset(0),
1105                            push_items * sizeof(struct btrfs_key_ptr));
1106
1107         if (push_items < src_nritems) {
1108                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1109                                       btrfs_node_key_ptr_offset(push_items),
1110                                       (src_nritems - push_items) *
1111                                       sizeof(struct btrfs_key_ptr));
1112         }
1113         btrfs_set_header_nritems(src, src_nritems - push_items);
1114         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1115         btrfs_mark_buffer_dirty(src);
1116         btrfs_mark_buffer_dirty(dst);
1117         return ret;
1118 }
1119
1120 /*
1121  * try to push data from one node into the next node right in the
1122  * tree.
1123  *
1124  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1125  * error, and > 0 if there was no room in the right hand block.
1126  *
1127  * this will  only push up to 1/2 the contents of the left node over
1128  */
1129 static int balance_node_right(struct btrfs_trans_handle *trans,
1130                               struct btrfs_root *root,
1131                               struct extent_buffer *dst,
1132                               struct extent_buffer *src)
1133 {
1134         int push_items = 0;
1135         int max_push;
1136         int src_nritems;
1137         int dst_nritems;
1138         int ret = 0;
1139
1140         src_nritems = btrfs_header_nritems(src);
1141         dst_nritems = btrfs_header_nritems(dst);
1142         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1143         if (push_items <= 0)
1144                 return 1;
1145
1146         max_push = src_nritems / 2 + 1;
1147         /* don't try to empty the node */
1148         if (max_push >= src_nritems)
1149                 return 1;
1150
1151         if (max_push < push_items)
1152                 push_items = max_push;
1153
1154         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1155                                       btrfs_node_key_ptr_offset(0),
1156                                       (dst_nritems) *
1157                                       sizeof(struct btrfs_key_ptr));
1158
1159         copy_extent_buffer(dst, src,
1160                            btrfs_node_key_ptr_offset(0),
1161                            btrfs_node_key_ptr_offset(src_nritems - push_items),
1162                            push_items * sizeof(struct btrfs_key_ptr));
1163
1164         btrfs_set_header_nritems(src, src_nritems - push_items);
1165         btrfs_set_header_nritems(dst, dst_nritems + push_items);
1166
1167         btrfs_mark_buffer_dirty(src);
1168         btrfs_mark_buffer_dirty(dst);
1169         return ret;
1170 }
1171
1172 /*
1173  * helper function to insert a new root level in the tree.
1174  * A new node is allocated, and a single item is inserted to
1175  * point to the existing root
1176  *
1177  * returns zero on success or < 0 on failure.
1178  */
1179 static int insert_new_root(struct btrfs_trans_handle *trans,
1180                            struct btrfs_root *root,
1181                            struct btrfs_path *path, int level)
1182 {
1183         struct extent_buffer *lower;
1184         struct extent_buffer *c;
1185         struct btrfs_disk_key lower_key;
1186
1187         BUG_ON(path->nodes[level]);
1188         BUG_ON(path->nodes[level-1] != root->node);
1189
1190         c = btrfs_alloc_free_block(trans, root,
1191                                    extent_buffer_blocknr(root->node), 0);
1192         if (IS_ERR(c))
1193                 return PTR_ERR(c);
1194         memset_extent_buffer(c, 0, 0, root->nodesize);
1195         btrfs_set_header_nritems(c, 1);
1196         btrfs_set_header_level(c, level);
1197         btrfs_set_header_blocknr(c, extent_buffer_blocknr(c));
1198         btrfs_set_header_generation(c, trans->transid);
1199         btrfs_set_header_owner(c, root->root_key.objectid);
1200         lower = path->nodes[level-1];
1201
1202         write_extent_buffer(c, root->fs_info->fsid,
1203                             (unsigned long)btrfs_header_fsid(c),
1204                             BTRFS_FSID_SIZE);
1205         if (level == 1)
1206                 btrfs_item_key(lower, &lower_key, 0);
1207         else
1208                 btrfs_node_key(lower, &lower_key, 0);
1209         btrfs_set_node_key(c, &lower_key, 0);
1210         btrfs_set_node_blockptr(c, 0, extent_buffer_blocknr(lower));
1211
1212         btrfs_mark_buffer_dirty(c);
1213
1214         /* the super has an extra ref to root->node */
1215         free_extent_buffer(root->node);
1216         root->node = c;
1217         extent_buffer_get(c);
1218         path->nodes[level] = c;
1219         path->slots[level] = 0;
1220         return 0;
1221 }
1222
1223 /*
1224  * worker function to insert a single pointer in a node.
1225  * the node should have enough room for the pointer already
1226  *
1227  * slot and level indicate where you want the key to go, and
1228  * blocknr is the block the key points to.
1229  *
1230  * returns zero on success and < 0 on any error
1231  */
1232 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1233                       *root, struct btrfs_path *path, struct btrfs_disk_key
1234                       *key, u64 blocknr, int slot, int level)
1235 {
1236         struct extent_buffer *lower;
1237         int nritems;
1238
1239         BUG_ON(!path->nodes[level]);
1240         lower = path->nodes[level];
1241         nritems = btrfs_header_nritems(lower);
1242         if (slot > nritems)
1243                 BUG();
1244         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1245                 BUG();
1246         if (slot != nritems) {
1247                 memmove_extent_buffer(lower,
1248                               btrfs_node_key_ptr_offset(slot + 1),
1249                               btrfs_node_key_ptr_offset(slot),
1250                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
1251         }
1252         btrfs_set_node_key(lower, key, slot);
1253         btrfs_set_node_blockptr(lower, slot, blocknr);
1254         btrfs_set_header_nritems(lower, nritems + 1);
1255         btrfs_mark_buffer_dirty(lower);
1256         check_node(root, path, level);
1257         return 0;
1258 }
1259
1260 /*
1261  * split the node at the specified level in path in two.
1262  * The path is corrected to point to the appropriate node after the split
1263  *
1264  * Before splitting this tries to make some room in the node by pushing
1265  * left and right, if either one works, it returns right away.
1266  *
1267  * returns 0 on success and < 0 on failure
1268  */
1269 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1270                       *root, struct btrfs_path *path, int level)
1271 {
1272         struct extent_buffer *c;
1273         struct extent_buffer *split;
1274         struct btrfs_disk_key disk_key;
1275         int mid;
1276         int ret;
1277         int wret;
1278         u32 c_nritems;
1279
1280         c = path->nodes[level];
1281         if (c == root->node) {
1282                 /* trying to split the root, lets make a new one */
1283                 ret = insert_new_root(trans, root, path, level + 1);
1284                 if (ret)
1285                         return ret;
1286         } else {
1287                 ret = push_nodes_for_insert(trans, root, path, level);
1288                 c = path->nodes[level];
1289                 if (!ret && btrfs_header_nritems(c) <
1290                     BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
1291                         return 0;
1292                 if (ret < 0)
1293                         return ret;
1294         }
1295
1296         c_nritems = btrfs_header_nritems(c);
1297         split = btrfs_alloc_free_block(trans, root,
1298                                        extent_buffer_blocknr(c), 0);
1299         if (IS_ERR(split))
1300                 return PTR_ERR(split);
1301
1302         btrfs_set_header_flags(split, btrfs_header_flags(c));
1303         btrfs_set_header_level(split, btrfs_header_level(c));
1304         btrfs_set_header_blocknr(split, extent_buffer_blocknr(split));
1305         btrfs_set_header_generation(split, trans->transid);
1306         btrfs_set_header_owner(split, root->root_key.objectid);
1307         write_extent_buffer(split, root->fs_info->fsid,
1308                             (unsigned long)btrfs_header_fsid(split),
1309                             BTRFS_FSID_SIZE);
1310
1311         mid = (c_nritems + 1) / 2;
1312
1313         copy_extent_buffer(split, c,
1314                            btrfs_node_key_ptr_offset(0),
1315                            btrfs_node_key_ptr_offset(mid),
1316                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1317         btrfs_set_header_nritems(split, c_nritems - mid);
1318         btrfs_set_header_nritems(c, mid);
1319         ret = 0;
1320
1321         btrfs_mark_buffer_dirty(c);
1322         btrfs_mark_buffer_dirty(split);
1323
1324         btrfs_node_key(split, &disk_key, 0);
1325         wret = insert_ptr(trans, root, path, &disk_key,
1326                           extent_buffer_blocknr(split),
1327                           path->slots[level + 1] + 1,
1328                           level + 1);
1329         if (wret)
1330                 ret = wret;
1331
1332         if (path->slots[level] >= mid) {
1333                 path->slots[level] -= mid;
1334                 free_extent_buffer(c);
1335                 path->nodes[level] = split;
1336                 path->slots[level + 1] += 1;
1337         } else {
1338                 free_extent_buffer(split);
1339         }
1340         return ret;
1341 }
1342
1343 /*
1344  * how many bytes are required to store the items in a leaf.  start
1345  * and nr indicate which items in the leaf to check.  This totals up the
1346  * space used both by the item structs and the item data
1347  */
1348 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1349 {
1350         int data_len;
1351         int nritems = btrfs_header_nritems(l);
1352         int end = min(nritems, start + nr) - 1;
1353
1354         if (!nr)
1355                 return 0;
1356         data_len = btrfs_item_end_nr(l, start);
1357         data_len = data_len - btrfs_item_offset_nr(l, end);
1358         data_len += sizeof(struct btrfs_item) * nr;
1359         WARN_ON(data_len < 0);
1360         return data_len;
1361 }
1362
1363 /*
1364  * The space between the end of the leaf items and
1365  * the start of the leaf data.  IOW, how much room
1366  * the leaf has left for both items and data
1367  */
1368 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1369 {
1370         int nritems = btrfs_header_nritems(leaf);
1371         int ret;
1372         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1373         if (ret < 0) {
1374                 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1375                        ret, BTRFS_LEAF_DATA_SIZE(root),
1376                        leaf_space_used(leaf, 0, nritems), nritems);
1377         }
1378         return ret;
1379 }
1380
1381 /*
1382  * push some data in the path leaf to the right, trying to free up at
1383  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1384  *
1385  * returns 1 if the push failed because the other node didn't have enough
1386  * room, 0 if everything worked out and < 0 if there were major errors.
1387  */
1388 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1389                            *root, struct btrfs_path *path, int data_size)
1390 {
1391         struct extent_buffer *left = path->nodes[0];
1392         struct extent_buffer *right;
1393         struct extent_buffer *upper;
1394         struct btrfs_disk_key disk_key;
1395         int slot;
1396         int i;
1397         int free_space;
1398         int push_space = 0;
1399         int push_items = 0;
1400         struct btrfs_item *item;
1401         u32 left_nritems;
1402         u32 right_nritems;
1403         u32 data_end;
1404         int ret;
1405
1406         slot = path->slots[1];
1407         if (!path->nodes[1]) {
1408                 return 1;
1409         }
1410         upper = path->nodes[1];
1411         if (slot >= btrfs_header_nritems(upper) - 1)
1412                 return 1;
1413
1414         right = read_tree_block(root, btrfs_node_blockptr(upper, slot + 1));
1415         free_space = btrfs_leaf_free_space(root, right);
1416         if (free_space < data_size + sizeof(struct btrfs_item)) {
1417                 free_extent_buffer(right);
1418                 return 1;
1419         }
1420
1421         /* cow and double check */
1422         ret = btrfs_cow_block(trans, root, right, upper,
1423                               slot + 1, &right);
1424         if (ret) {
1425                 free_extent_buffer(right);
1426                 return 1;
1427         }
1428         free_space = btrfs_leaf_free_space(root, right);
1429         if (free_space < data_size + sizeof(struct btrfs_item)) {
1430                 free_extent_buffer(right);
1431                 return 1;
1432         }
1433
1434         left_nritems = btrfs_header_nritems(left);
1435         if (left_nritems == 0) {
1436                 free_extent_buffer(right);
1437                 return 1;
1438         }
1439
1440         for (i = left_nritems - 1; i >= 1; i--) {
1441                 item = btrfs_item_nr(left, i);
1442                 if (path->slots[0] == i)
1443                         push_space += data_size + sizeof(*item);
1444                 if (btrfs_item_size(left, item) + sizeof(*item) + push_space >
1445                     free_space)
1446                         break;
1447                 push_items++;
1448                 push_space += btrfs_item_size(left, item) + sizeof(*item);
1449         }
1450
1451         if (push_items == 0) {
1452                 free_extent_buffer(right);
1453                 return 1;
1454         }
1455
1456         if (push_items == left_nritems)
1457                 WARN_ON(1);
1458
1459         /* push left to right */
1460         right_nritems = btrfs_header_nritems(right);
1461         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1462         push_space -= leaf_data_end(root, left);
1463
1464         /* make room in the right data area */
1465         data_end = leaf_data_end(root, right);
1466         memmove_extent_buffer(right,
1467                               btrfs_leaf_data(right) + data_end - push_space,
1468                               btrfs_leaf_data(right) + data_end,
1469                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
1470
1471         /* copy from the left data area */
1472         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1473                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1474                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1475                      push_space);
1476
1477         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1478                               btrfs_item_nr_offset(0),
1479                               right_nritems * sizeof(struct btrfs_item));
1480
1481         /* copy the items from left to right */
1482         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1483                    btrfs_item_nr_offset(left_nritems - push_items),
1484                    push_items * sizeof(struct btrfs_item));
1485
1486         /* update the item pointers */
1487         right_nritems += push_items;
1488         btrfs_set_header_nritems(right, right_nritems);
1489         push_space = BTRFS_LEAF_DATA_SIZE(root);
1490         for (i = 0; i < right_nritems; i++) {
1491                 item = btrfs_item_nr(right, i);
1492                 btrfs_set_item_offset(right, item, push_space -
1493                                       btrfs_item_size(right, item));
1494                 push_space = btrfs_item_offset(right, item);
1495         }
1496         left_nritems -= push_items;
1497         btrfs_set_header_nritems(left, left_nritems);
1498
1499         btrfs_mark_buffer_dirty(left);
1500         btrfs_mark_buffer_dirty(right);
1501
1502         btrfs_item_key(right, &disk_key, 0);
1503         btrfs_set_node_key(upper, &disk_key, slot + 1);
1504         btrfs_mark_buffer_dirty(upper);
1505
1506         /* then fixup the leaf pointer in the path */
1507         if (path->slots[0] >= left_nritems) {
1508                 path->slots[0] -= left_nritems;
1509                 free_extent_buffer(path->nodes[0]);
1510                 path->nodes[0] = right;
1511                 path->slots[1] += 1;
1512         } else {
1513                 free_extent_buffer(right);
1514         }
1515         if (path->nodes[1])
1516                 check_node(root, path, 1);
1517         return 0;
1518 }
1519 /*
1520  * push some data in the path leaf to the left, trying to free up at
1521  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1522  */
1523 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1524                           *root, struct btrfs_path *path, int data_size)
1525 {
1526         struct btrfs_disk_key disk_key;
1527         struct extent_buffer *right = path->nodes[0];
1528         struct extent_buffer *left;
1529         int slot;
1530         int i;
1531         int free_space;
1532         int push_space = 0;
1533         int push_items = 0;
1534         struct btrfs_item *item;
1535         u32 old_left_nritems;
1536         u32 right_nritems;
1537         int ret = 0;
1538         int wret;
1539
1540         slot = path->slots[1];
1541         if (slot == 0)
1542                 return 1;
1543         if (!path->nodes[1])
1544                 return 1;
1545
1546         left = read_tree_block(root, btrfs_node_blockptr(path->nodes[1],
1547                                                          slot - 1));
1548         free_space = btrfs_leaf_free_space(root, left);
1549         if (free_space < data_size + sizeof(struct btrfs_item)) {
1550                 free_extent_buffer(left);
1551                 return 1;
1552         }
1553
1554         /* cow and double check */
1555         ret = btrfs_cow_block(trans, root, left,
1556                               path->nodes[1], slot - 1, &left);
1557         if (ret) {
1558                 /* we hit -ENOSPC, but it isn't fatal here */
1559                 free_extent_buffer(left);
1560                 return 1;
1561         }
1562         free_space = btrfs_leaf_free_space(root, left);
1563         if (free_space < data_size + sizeof(struct btrfs_item)) {
1564                 free_extent_buffer(left);
1565                 return 1;
1566         }
1567
1568         right_nritems = btrfs_header_nritems(right);
1569         if (right_nritems == 0) {
1570                 free_extent_buffer(left);
1571                 return 1;
1572         }
1573
1574         for (i = 0; i < right_nritems - 1; i++) {
1575                 item = btrfs_item_nr(right, i);
1576                 if (path->slots[0] == i)
1577                         push_space += data_size + sizeof(*item);
1578                 if (btrfs_item_size(right, item) + sizeof(*item) + push_space >
1579                     free_space)
1580                         break;
1581                 push_items++;
1582                 push_space += btrfs_item_size(right, item) + sizeof(*item);
1583         }
1584         if (push_items == 0) {
1585                 free_extent_buffer(left);
1586                 return 1;
1587         }
1588         if (push_items == btrfs_header_nritems(right))
1589                 WARN_ON(1);
1590
1591         /* push data from right to left */
1592         copy_extent_buffer(left, right,
1593                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
1594                            btrfs_item_nr_offset(0),
1595                            push_items * sizeof(struct btrfs_item));
1596
1597         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1598                      btrfs_item_offset_nr(right, push_items -1);
1599
1600         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1601                      leaf_data_end(root, left) - push_space,
1602                      btrfs_leaf_data(right) +
1603                      btrfs_item_offset_nr(right, push_items - 1),
1604                      push_space);
1605         old_left_nritems = btrfs_header_nritems(left);
1606         BUG_ON(old_left_nritems < 0);
1607
1608         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1609                 u32 ioff;
1610                 item = btrfs_item_nr(left, i);
1611                 ioff = btrfs_item_offset(left, item);
1612                 btrfs_set_item_offset(left, item,
1613                       ioff - (BTRFS_LEAF_DATA_SIZE(root) -
1614                       btrfs_item_offset_nr(left, old_left_nritems - 1)));
1615         }
1616         btrfs_set_header_nritems(left, old_left_nritems + push_items);
1617
1618         /* fixup right node */
1619         push_space = btrfs_item_offset_nr(right, push_items - 1) -
1620                                           leaf_data_end(root, right);
1621         memmove_extent_buffer(right, btrfs_leaf_data(right) +
1622                               BTRFS_LEAF_DATA_SIZE(root) - push_space,
1623                               btrfs_leaf_data(right) +
1624                               leaf_data_end(root, right), push_space);
1625
1626         memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1627                               btrfs_item_nr_offset(push_items),
1628                              (btrfs_header_nritems(right) - push_items) *
1629                              sizeof(struct btrfs_item));
1630
1631         right_nritems = btrfs_header_nritems(right) - push_items;
1632         btrfs_set_header_nritems(right, right_nritems);
1633         push_space = BTRFS_LEAF_DATA_SIZE(root);
1634
1635         for (i = 0; i < right_nritems; i++) {
1636                 item = btrfs_item_nr(right, i);
1637                 btrfs_set_item_offset(right, item, push_space -
1638                                       btrfs_item_size(right, item));
1639                 push_space = btrfs_item_offset(right, item);
1640         }
1641
1642         btrfs_mark_buffer_dirty(left);
1643         btrfs_mark_buffer_dirty(right);
1644
1645         btrfs_item_key(right, &disk_key, 0);
1646         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1647         if (wret)
1648                 ret = wret;
1649
1650         /* then fixup the leaf pointer in the path */
1651         if (path->slots[0] < push_items) {
1652                 path->slots[0] += old_left_nritems;
1653                 free_extent_buffer(path->nodes[0]);
1654                 path->nodes[0] = left;
1655                 path->slots[1] -= 1;
1656         } else {
1657                 free_extent_buffer(left);
1658                 path->slots[0] -= push_items;
1659         }
1660         BUG_ON(path->slots[0] < 0);
1661         if (path->nodes[1])
1662                 check_node(root, path, 1);
1663         return ret;
1664 }
1665
1666 /*
1667  * split the path's leaf in two, making sure there is at least data_size
1668  * available for the resulting leaf level of the path.
1669  *
1670  * returns 0 if all went well and < 0 on failure.
1671  */
1672 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1673                       *root, struct btrfs_key *ins_key,
1674                       struct btrfs_path *path, int data_size)
1675 {
1676         struct extent_buffer *l;
1677         u32 nritems;
1678         int mid;
1679         int slot;
1680         struct extent_buffer *right;
1681         int space_needed = data_size + sizeof(struct btrfs_item);
1682         int data_copy_size;
1683         int rt_data_off;
1684         int i;
1685         int ret = 0;
1686         int wret;
1687         int double_split = 0;
1688         struct btrfs_disk_key disk_key;
1689
1690         /* first try to make some room by pushing left and right */
1691         wret = push_leaf_left(trans, root, path, data_size);
1692         if (wret < 0)
1693                 return wret;
1694         if (wret) {
1695                 wret = push_leaf_right(trans, root, path, data_size);
1696                 if (wret < 0)
1697                         return wret;
1698         }
1699         l = path->nodes[0];
1700
1701         /* did the pushes work? */
1702         if (btrfs_leaf_free_space(root, l) >=
1703             sizeof(struct btrfs_item) + data_size)
1704                 return 0;
1705
1706         if (!path->nodes[1]) {
1707                 ret = insert_new_root(trans, root, path, 1);
1708                 if (ret)
1709                         return ret;
1710         }
1711         slot = path->slots[0];
1712         nritems = btrfs_header_nritems(l);
1713         mid = (nritems + 1)/ 2;
1714
1715         right = btrfs_alloc_free_block(trans, root,
1716                                               extent_buffer_blocknr(l), 0);
1717         if (IS_ERR(right))
1718                 return PTR_ERR(right);
1719
1720         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1721         btrfs_set_header_blocknr(right, extent_buffer_blocknr(right));
1722         btrfs_set_header_generation(right, trans->transid);
1723         btrfs_set_header_owner(right, root->root_key.objectid);
1724         btrfs_set_header_level(right, 0);
1725         write_extent_buffer(right, root->fs_info->fsid,
1726                             (unsigned long)btrfs_header_fsid(right),
1727                             BTRFS_FSID_SIZE);
1728
1729         if (mid <= slot) {
1730                 if (nritems == 1 ||
1731                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1732                         BTRFS_LEAF_DATA_SIZE(root)) {
1733                         if (slot >= nritems) {
1734                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1735                                 btrfs_set_header_nritems(right, 0);
1736                                 wret = insert_ptr(trans, root, path,
1737                                                   &disk_key,
1738                                                   extent_buffer_blocknr(right),
1739                                                   path->slots[1] + 1, 1);
1740                                 if (wret)
1741                                         ret = wret;
1742                                 free_extent_buffer(path->nodes[0]);
1743                                 path->nodes[0] = right;
1744                                 path->slots[0] = 0;
1745                                 path->slots[1] += 1;
1746                                 return ret;
1747                         }
1748                         mid = slot;
1749                         double_split = 1;
1750                 }
1751         } else {
1752                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1753                         BTRFS_LEAF_DATA_SIZE(root)) {
1754                         if (slot == 0) {
1755                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1756                                 btrfs_set_header_nritems(right, 0);
1757                                 wret = insert_ptr(trans, root, path,
1758                                                   &disk_key,
1759                                                   extent_buffer_blocknr(right),
1760                                                   path->slots[1], 1);
1761                                 if (wret)
1762                                         ret = wret;
1763                                 free_extent_buffer(path->nodes[0]);
1764                                 path->nodes[0] = right;
1765                                 path->slots[0] = 0;
1766                                 if (path->slots[1] == 0) {
1767                                         wret = fixup_low_keys(trans, root,
1768                                                    path, &disk_key, 1);
1769                                         if (wret)
1770                                                 ret = wret;
1771                                 }
1772                                 return ret;
1773                         }
1774                         mid = slot;
1775                         double_split = 1;
1776                 }
1777         }
1778         nritems = nritems - mid;
1779         btrfs_set_header_nritems(right, nritems);
1780         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
1781
1782         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
1783                            btrfs_item_nr_offset(mid),
1784                            nritems * sizeof(struct btrfs_item));
1785
1786         copy_extent_buffer(right, l,
1787                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1788                      data_copy_size, btrfs_leaf_data(l) +
1789                      leaf_data_end(root, l), data_copy_size);
1790
1791         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1792                       btrfs_item_end_nr(l, mid);
1793
1794         for (i = 0; i < nritems; i++) {
1795                 struct btrfs_item *item = btrfs_item_nr(right, i);
1796                 u32 ioff = btrfs_item_offset(right, item);
1797                 btrfs_set_item_offset(right, item, ioff + rt_data_off);
1798         }
1799
1800         btrfs_set_header_nritems(l, mid);
1801         ret = 0;
1802         btrfs_item_key(right, &disk_key, 0);
1803         wret = insert_ptr(trans, root, path, &disk_key,
1804                           extent_buffer_blocknr(right), path->slots[1] + 1, 1);
1805         if (wret)
1806                 ret = wret;
1807
1808         btrfs_mark_buffer_dirty(right);
1809         btrfs_mark_buffer_dirty(l);
1810         BUG_ON(path->slots[0] != slot);
1811
1812         if (mid <= slot) {
1813                 free_extent_buffer(path->nodes[0]);
1814                 path->nodes[0] = right;
1815                 path->slots[0] -= mid;
1816                 path->slots[1] += 1;
1817         } else
1818                 free_extent_buffer(right);
1819
1820         BUG_ON(path->slots[0] < 0);
1821         check_node(root, path, 1);
1822         check_leaf(root, path, 0);
1823
1824         if (!double_split)
1825                 return ret;
1826
1827         right = btrfs_alloc_free_block(trans, root,
1828                                        extent_buffer_blocknr(l), 0);
1829         if (IS_ERR(right))
1830                 return PTR_ERR(right);
1831
1832         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
1833         btrfs_set_header_blocknr(right, extent_buffer_blocknr(right));
1834         btrfs_set_header_generation(right, trans->transid);
1835         btrfs_set_header_owner(right, root->root_key.objectid);
1836         btrfs_set_header_level(right, 0);
1837         write_extent_buffer(right, root->fs_info->fsid,
1838                             (unsigned long)btrfs_header_fsid(right),
1839                             BTRFS_FSID_SIZE);
1840
1841         btrfs_cpu_key_to_disk(&disk_key, ins_key);
1842         btrfs_set_header_nritems(right, 0);
1843         wret = insert_ptr(trans, root, path,
1844                           &disk_key,
1845                           extent_buffer_blocknr(right),
1846                           path->slots[1], 1);
1847         if (wret)
1848                 ret = wret;
1849         if (path->slots[1] == 0) {
1850                 wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1851                 if (wret)
1852                         ret = wret;
1853         }
1854         free_extent_buffer(path->nodes[0]);
1855         path->nodes[0] = right;
1856         path->slots[0] = 0;
1857         check_node(root, path, 1);
1858         check_leaf(root, path, 0);
1859         return ret;
1860 }
1861
1862 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
1863                         struct btrfs_root *root,
1864                         struct btrfs_path *path,
1865                         u32 new_size)
1866 {
1867         int ret = 0;
1868         int slot;
1869         int slot_orig;
1870         struct extent_buffer *leaf;
1871         struct btrfs_item *item;
1872         u32 nritems;
1873         unsigned int data_end;
1874         unsigned int old_data_start;
1875         unsigned int old_size;
1876         unsigned int size_diff;
1877         int i;
1878
1879         slot_orig = path->slots[0];
1880         leaf = path->nodes[0];
1881
1882         nritems = btrfs_header_nritems(leaf);
1883         data_end = leaf_data_end(root, leaf);
1884
1885         slot = path->slots[0];
1886         old_data_start = btrfs_item_offset_nr(leaf, slot);
1887         old_size = btrfs_item_size_nr(leaf, slot);
1888         BUG_ON(old_size <= new_size);
1889         size_diff = old_size - new_size;
1890
1891         BUG_ON(slot < 0);
1892         BUG_ON(slot >= nritems);
1893
1894         /*
1895          * item0..itemN ... dataN.offset..dataN.size .. data0.size
1896          */
1897         /* first correct the data pointers */
1898         for (i = slot; i < nritems; i++) {
1899                 u32 ioff;
1900                 item = btrfs_item_nr(leaf, i);
1901                 ioff = btrfs_item_offset(leaf, item);
1902                 btrfs_set_item_offset(leaf, item, ioff + size_diff);
1903         }
1904         /* shift the data */
1905         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
1906                       data_end + size_diff, btrfs_leaf_data(leaf) +
1907                       data_end, old_data_start + new_size - data_end);
1908
1909         item = btrfs_item_nr(leaf, slot);
1910         btrfs_set_item_size(leaf, item, new_size);
1911         btrfs_mark_buffer_dirty(leaf);
1912
1913         ret = 0;
1914         if (btrfs_leaf_free_space(root, leaf) < 0) {
1915                 btrfs_print_leaf(root, leaf);
1916                 BUG();
1917         }
1918         check_leaf(root, path, 0);
1919         return ret;
1920 }
1921
1922 int btrfs_extend_item(struct btrfs_trans_handle *trans,
1923                       struct btrfs_root *root, struct btrfs_path *path,
1924                       u32 data_size)
1925 {
1926         int ret = 0;
1927         int slot;
1928         int slot_orig;
1929         struct extent_buffer *leaf;
1930         struct btrfs_item *item;
1931         u32 nritems;
1932         unsigned int data_end;
1933         unsigned int old_data;
1934         unsigned int old_size;
1935         int i;
1936
1937         slot_orig = path->slots[0];
1938         leaf = path->nodes[0];
1939
1940         nritems = btrfs_header_nritems(leaf);
1941         data_end = leaf_data_end(root, leaf);
1942
1943         if (btrfs_leaf_free_space(root, leaf) < data_size) {
1944                 btrfs_print_leaf(root, leaf);
1945                 BUG();
1946         }
1947         slot = path->slots[0];
1948         old_data = btrfs_item_end_nr(leaf, slot);
1949
1950         BUG_ON(slot < 0);
1951         BUG_ON(slot >= nritems);
1952
1953         /*
1954          * item0..itemN ... dataN.offset..dataN.size .. data0.size
1955          */
1956         /* first correct the data pointers */
1957         for (i = slot; i < nritems; i++) {
1958                 u32 ioff;
1959                 item = btrfs_item_nr(leaf, i);
1960                 ioff = btrfs_item_offset(leaf, item);
1961                 btrfs_set_item_offset(leaf, item, ioff - data_size);
1962         }
1963
1964         /* shift the data */
1965         memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
1966                       data_end - data_size, btrfs_leaf_data(leaf) +
1967                       data_end, old_data - data_end);
1968
1969         data_end = old_data;
1970         old_size = btrfs_item_size_nr(leaf, slot);
1971         item = btrfs_item_nr(leaf, slot);
1972         btrfs_set_item_size(leaf, item, old_size + data_size);
1973         btrfs_mark_buffer_dirty(leaf);
1974
1975         ret = 0;
1976         if (btrfs_leaf_free_space(root, leaf) < 0) {
1977                 btrfs_print_leaf(root, leaf);
1978                 BUG();
1979         }
1980         check_leaf(root, path, 0);
1981         return ret;
1982 }
1983
1984 /*
1985  * Given a key and some data, insert an item into the tree.
1986  * This does all the path init required, making room in the tree if needed.
1987  */
1988 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans,
1989                             struct btrfs_root *root,
1990                             struct btrfs_path *path,
1991                             struct btrfs_key *cpu_key, u32 data_size)
1992 {
1993         struct extent_buffer *leaf;
1994         struct btrfs_item *item;
1995         int ret = 0;
1996         int slot;
1997         int slot_orig;
1998         u32 nritems;
1999         unsigned int data_end;
2000         struct btrfs_disk_key disk_key;
2001
2002         btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2003
2004         /* create a root if there isn't one */
2005         if (!root->node)
2006                 BUG();
2007
2008         ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
2009         if (ret == 0) {
2010                 return -EEXIST;
2011         }
2012         if (ret < 0)
2013                 goto out;
2014
2015         slot_orig = path->slots[0];
2016         leaf = path->nodes[0];
2017
2018         nritems = btrfs_header_nritems(leaf);
2019         data_end = leaf_data_end(root, leaf);
2020
2021         if (btrfs_leaf_free_space(root, leaf) <
2022             sizeof(struct btrfs_item) + data_size) {
2023                 BUG();
2024         }
2025
2026         slot = path->slots[0];
2027         BUG_ON(slot < 0);
2028
2029         if (slot != nritems) {
2030                 int i;
2031                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2032
2033                 if (old_data < data_end) {
2034                         btrfs_print_leaf(root, leaf);
2035                         printk("slot %d old_data %d data_end %d\n",
2036                                slot, old_data, data_end);
2037                         BUG_ON(1);
2038                 }
2039                 /*
2040                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
2041                  */
2042                 /* first correct the data pointers */
2043                 for (i = slot; i < nritems; i++) {
2044                         u32 ioff;
2045                         item = btrfs_item_nr(leaf, i);
2046                         ioff = btrfs_item_offset(leaf, item);
2047                         btrfs_set_item_offset(leaf, item, ioff - data_size);
2048                 }
2049
2050                 /* shift the items */
2051                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
2052                               btrfs_item_nr_offset(slot),
2053                               (nritems - slot) * sizeof(struct btrfs_item));
2054
2055                 /* shift the data */
2056                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2057                               data_end - data_size, btrfs_leaf_data(leaf) +
2058                               data_end, old_data - data_end);
2059                 data_end = old_data;
2060         }
2061
2062         /* setup the item for the new data */
2063         btrfs_set_item_key(leaf, &disk_key, slot);
2064         item = btrfs_item_nr(leaf, slot);
2065         btrfs_set_item_offset(leaf, item, data_end - data_size);
2066         btrfs_set_item_size(leaf, item, data_size);
2067         btrfs_set_header_nritems(leaf, nritems + 1);
2068         btrfs_mark_buffer_dirty(leaf);
2069
2070         ret = 0;
2071         if (slot == 0)
2072                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2073
2074         if (btrfs_leaf_free_space(root, leaf) < 0) {
2075                 btrfs_print_leaf(root, leaf);
2076                 BUG();
2077         }
2078         check_leaf(root, path, 0);
2079 out:
2080         return ret;
2081 }
2082
2083 /*
2084  * Given a key and some data, insert an item into the tree.
2085  * This does all the path init required, making room in the tree if needed.
2086  */
2087 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2088                       *root, struct btrfs_key *cpu_key, void *data, u32
2089                       data_size)
2090 {
2091         int ret = 0;
2092         struct btrfs_path *path;
2093         struct extent_buffer *leaf;
2094         unsigned long ptr;
2095
2096         path = btrfs_alloc_path();
2097         BUG_ON(!path);
2098         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2099         if (!ret) {
2100                 leaf = path->nodes[0];
2101                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2102                 write_extent_buffer(leaf, data, ptr, data_size);
2103                 btrfs_mark_buffer_dirty(leaf);
2104         }
2105         btrfs_free_path(path);
2106         return ret;
2107 }
2108
2109 /*
2110  * delete the pointer from a given node.
2111  *
2112  * If the delete empties a node, the node is removed from the tree,
2113  * continuing all the way the root if required.  The root is converted into
2114  * a leaf if all the nodes are emptied.
2115  */
2116 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2117                    struct btrfs_path *path, int level, int slot)
2118 {
2119         struct extent_buffer *parent = path->nodes[level];
2120         u32 nritems;
2121         int ret = 0;
2122         int wret;
2123
2124         nritems = btrfs_header_nritems(parent);
2125         if (slot != nritems -1) {
2126                 memmove_extent_buffer(parent,
2127                               btrfs_node_key_ptr_offset(slot),
2128                               btrfs_node_key_ptr_offset(slot + 1),
2129                               sizeof(struct btrfs_key_ptr) *
2130                               (nritems - slot - 1));
2131         }
2132         nritems--;
2133         btrfs_set_header_nritems(parent, nritems);
2134         if (nritems == 0 && parent == root->node) {
2135                 BUG_ON(btrfs_header_level(root->node) != 1);
2136                 /* just turn the root into a leaf and break */
2137                 btrfs_set_header_level(root->node, 0);
2138         } else if (slot == 0) {
2139                 struct btrfs_disk_key disk_key;
2140
2141                 btrfs_node_key(parent, &disk_key, 0);
2142                 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2143                 if (wret)
2144                         ret = wret;
2145         }
2146         btrfs_mark_buffer_dirty(parent);
2147         return ret;
2148 }
2149
2150 /*
2151  * delete the item at the leaf level in path.  If that empties
2152  * the leaf, remove it from the tree
2153  */
2154 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2155                    struct btrfs_path *path)
2156 {
2157         int slot;
2158         struct extent_buffer *leaf;
2159         struct btrfs_item *item;
2160         int doff;
2161         int dsize;
2162         int ret = 0;
2163         int wret;
2164         u32 nritems;
2165
2166         leaf = path->nodes[0];
2167         slot = path->slots[0];
2168         doff = btrfs_item_offset_nr(leaf, slot);
2169         dsize = btrfs_item_size_nr(leaf, slot);
2170         nritems = btrfs_header_nritems(leaf);
2171
2172         if (slot != nritems - 1) {
2173                 int i;
2174                 int data_end = leaf_data_end(root, leaf);
2175
2176                 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2177                               data_end + dsize,
2178                               btrfs_leaf_data(leaf) + data_end,
2179                               doff - data_end);
2180
2181                 for (i = slot + 1; i < nritems; i++) {
2182                         u32 ioff;
2183                         item = btrfs_item_nr(leaf, i);
2184                         ioff = btrfs_item_offset(leaf, item);
2185                         btrfs_set_item_offset(leaf, item, ioff + dsize);
2186                 }
2187                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2188                               btrfs_item_nr_offset(slot + 1),
2189                               sizeof(struct btrfs_item) *
2190                               (nritems - slot - 1));
2191         }
2192         btrfs_set_header_nritems(leaf, nritems - 1);
2193         nritems--;
2194
2195         /* delete the leaf if we've emptied it */
2196         if (nritems == 0) {
2197                 if (leaf == root->node) {
2198                         btrfs_set_header_level(leaf, 0);
2199                 } else {
2200                         clean_tree_block(trans, root, leaf);
2201                         wait_on_tree_block_writeback(root, leaf);
2202                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
2203                         if (wret)
2204                                 ret = wret;
2205                         wret = btrfs_free_extent(trans, root,
2206                                                  extent_buffer_blocknr(leaf),
2207                                                  1, 1);
2208                         if (wret)
2209                                 ret = wret;
2210                 }
2211         } else {
2212                 int used = leaf_space_used(leaf, 0, nritems);
2213                 if (slot == 0) {
2214                         struct btrfs_disk_key disk_key;
2215
2216                         btrfs_item_key(leaf, &disk_key, 0);
2217                         wret = fixup_low_keys(trans, root, path,
2218                                               &disk_key, 1);
2219                         if (wret)
2220                                 ret = wret;
2221                 }
2222
2223                 /* delete the leaf if it is mostly empty */
2224                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
2225                         /* push_leaf_left fixes the path.
2226                          * make sure the path still points to our leaf
2227                          * for possible call to del_ptr below
2228                          */
2229                         slot = path->slots[1];
2230                         extent_buffer_get(leaf);
2231
2232                         wret = push_leaf_left(trans, root, path, 1);
2233                         if (wret < 0 && wret != -ENOSPC)
2234                                 ret = wret;
2235
2236                         if (path->nodes[0] == leaf &&
2237                             btrfs_header_nritems(leaf)) {
2238                                 wret = push_leaf_right(trans, root, path, 1);
2239                                 if (wret < 0 && wret != -ENOSPC)
2240                                         ret = wret;
2241                         }
2242
2243                         if (btrfs_header_nritems(leaf) == 0) {
2244                                 u64 blocknr = extent_buffer_blocknr(leaf);
2245
2246                                 clean_tree_block(trans, root, leaf);
2247                                 wait_on_tree_block_writeback(root, leaf);
2248
2249                                 wret = del_ptr(trans, root, path, 1, slot);
2250                                 if (wret)
2251                                         ret = wret;
2252
2253                                 free_extent_buffer(leaf);
2254                                 wret = btrfs_free_extent(trans, root, blocknr,
2255                                                          1, 1);
2256                                 if (wret)
2257                                         ret = wret;
2258                         } else {
2259                                 btrfs_mark_buffer_dirty(leaf);
2260                                 free_extent_buffer(leaf);
2261                         }
2262                 } else {
2263                         btrfs_mark_buffer_dirty(leaf);
2264                 }
2265         }
2266         return ret;
2267 }
2268
2269 /*
2270  * walk up the tree as far as required to find the next leaf.
2271  * returns 0 if it found something or 1 if there are no greater leaves.
2272  * returns < 0 on io errors.
2273  */
2274 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2275 {
2276         int slot;
2277         int level = 1;
2278         u64 blocknr;
2279         struct extent_buffer *c;
2280         struct extent_buffer *next = NULL;
2281
2282         while(level < BTRFS_MAX_LEVEL) {
2283                 if (!path->nodes[level])
2284                         return 1;
2285
2286                 slot = path->slots[level] + 1;
2287                 c = path->nodes[level];
2288                 if (slot >= btrfs_header_nritems(c)) {
2289                         level++;
2290                         continue;
2291                 }
2292
2293                 blocknr = btrfs_node_blockptr(c, slot);
2294                 if (next)
2295                         free_extent_buffer(next);
2296
2297                 if (path->reada)
2298                         reada_for_search(root, path, level, slot);
2299
2300                 next = read_tree_block(root, blocknr);
2301                 break;
2302         }
2303         path->slots[level] = slot;
2304         while(1) {
2305                 level--;
2306                 c = path->nodes[level];
2307                 free_extent_buffer(c);
2308                 path->nodes[level] = next;
2309                 path->slots[level] = 0;
2310                 if (!level)
2311                         break;
2312                 if (path->reada)
2313                         reada_for_search(root, path, level, 0);
2314                 next = read_tree_block(root, btrfs_node_blockptr(next, 0));
2315         }
2316         return 0;
2317 }