ctree.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include "kerncompat.h"
   4 #include "radix-tree.h"
   5 #include "ctree.h"
   6 #include "disk-io.h"
   7 #include "print-tree.h"
   8
   9 static int split_node(struct ctree_root *root, struct ctree_path *path,
  10                       int level);
  11 static int split_leaf(struct ctree_root *root, struct ctree_path *path,
  12                       int data_size);
  13 static int push_node_left(struct ctree_root *root, struct tree_buffer *dst,
  14                           struct tree_buffer *src);
  15 static int balance_node_right(struct ctree_root *root,
  16                               struct tree_buffer *dst_buf,
  17                               struct tree_buffer *src_buf);
  18 static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
  19                    int slot);
  20
  21 inline void init_path(struct ctree_path *p)
  22 {
  23         memset(p, 0, sizeof(*p));
  24 }
  25
  26 void release_path(struct ctree_root *root, struct ctree_path *p)
  27 {
  28         int i;
  29         for (i = 0; i < MAX_LEVEL; i++) {
  30                 if (!p->nodes[i])
  31                         break;
  32                 tree_block_release(root, p->nodes[i]);
  33         }
  34         memset(p, 0, sizeof(*p));
  35 }
  36
  37 int btrfs_cow_block(struct ctree_root *root,
  38                     struct tree_buffer *buf,
  39                     struct tree_buffer *parent,
  40                     int parent_slot,
  41                     struct tree_buffer **cow_ret)
  42 {
  43         struct tree_buffer *cow;
  44
  45         if (!list_empty(&buf->dirty)) {
  46                 *cow_ret = buf;
  47                 return 0;
  48         }
  49         cow = alloc_free_block(root);
  50         memcpy(&cow->node, &buf->node, sizeof(buf->node));
  51         btrfs_set_header_blocknr(&cow->node.header, cow->blocknr);
  52         *cow_ret = cow;
  53         btrfs_inc_ref(root, buf);
  54         if (buf == root->node) {
  55                 root->node = cow;
  56                 cow->count++;
  57                 if (buf != root->commit_root)
  58                         free_extent(root, buf->blocknr, 1);
  59                 tree_block_release(root, buf);
  60         } else {
  61                 parent->node.blockptrs[parent_slot] = cow->blocknr;
  62                 BUG_ON(list_empty(&parent->dirty));
  63                 free_extent(root, buf->blocknr, 1);
  64         }
  65         tree_block_release(root, buf);
  66         return 0;
  67 }
  68
  69 /*
  70  * The leaf data grows from end-to-front in the node.
  71  * this returns the address of the start of the last item,
  72  * which is the stop of the leaf data stack
  73  */
  74 static inline unsigned int leaf_data_end(struct leaf *leaf)
  75 {
  76         u32 nr = btrfs_header_nritems(&leaf->header);
  77         if (nr == 0)
  78                 return sizeof(leaf->data);
  79         return leaf->items[nr-1].offset;
  80 }
  81
  82 /*
  83  * The space between the end of the leaf items and
  84  * the start of the leaf data.  IOW, how much room
  85  * the leaf has left for both items and data
  86  */
  87 int leaf_free_space(struct leaf *leaf)
  88 {
  89         int data_end = leaf_data_end(leaf);
  90         int nritems = btrfs_header_nritems(&leaf->header);
  91         char *items_end = (char *)(leaf->items + nritems + 1);
  92         return (char *)(leaf->data + data_end) - (char *)items_end;
  93 }
  94
  95 /*
  96  * compare two keys in a memcmp fashion
  97  */
  98 int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
  99 {
 100         struct btrfs_key k1;
 101
 102         btrfs_disk_key_to_cpu(&k1, disk);
 103
 104         if (k1.objectid > k2->objectid)
 105                 return 1;
 106         if (k1.objectid < k2->objectid)
 107                 return -1;
 108         if (k1.flags > k2->flags)
 109                 return 1;
 110         if (k1.flags < k2->flags)
 111                 return -1;
 112         if (k1.offset > k2->offset)
 113                 return 1;
 114         if (k1.offset < k2->offset)
 115                 return -1;
 116         return 0;
 117 }
 118
 119 int check_node(struct ctree_path *path, int level)
 120 {
 121         int i;
 122         struct node *parent = NULL;
 123         struct node *node = &path->nodes[level]->node;
 124         int parent_slot;
 125         u32 nritems = btrfs_header_nritems(&node->header);
 126
 127         if (path->nodes[level + 1])
 128                 parent = &path->nodes[level + 1]->node;
 129         parent_slot = path->slots[level + 1];
 130         BUG_ON(nritems == 0);
 131         if (parent) {
 132                 struct btrfs_disk_key *parent_key;
 133                 parent_key = &parent->keys[parent_slot];
 134                 BUG_ON(memcmp(parent_key, node->keys,
 135                               sizeof(struct btrfs_disk_key)));
 136                 BUG_ON(parent->blockptrs[parent_slot] !=
 137                        btrfs_header_blocknr(&node->header));
 138         }
 139         BUG_ON(nritems > NODEPTRS_PER_BLOCK);
 140         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 141                 struct btrfs_key cpukey;
 142                 btrfs_disk_key_to_cpu(&cpukey, &node->keys[i + 1]);
 143                 BUG_ON(comp_keys(&node->keys[i], &cpukey) >= 0);
 144         }
 145         return 0;
 146 }
 147
 148 int check_leaf(struct ctree_path *path, int level)
 149 {
 150         int i;
 151         struct leaf *leaf = &path->nodes[level]->leaf;
 152         struct node *parent = NULL;
 153         int parent_slot;
 154         u32 nritems = btrfs_header_nritems(&leaf->header);
 155
 156         if (path->nodes[level + 1])
 157                 parent = &path->nodes[level + 1]->node;
 158         parent_slot = path->slots[level + 1];
 159         BUG_ON(leaf_free_space(leaf) < 0);
 160
 161         if (nritems == 0)
 162                 return 0;
 163
 164         if (parent) {
 165                 struct btrfs_disk_key *parent_key;
 166                 parent_key = &parent->keys[parent_slot];
 167                 BUG_ON(memcmp(parent_key, &leaf->items[0].key,
 168                        sizeof(struct btrfs_disk_key)));
 169                 BUG_ON(parent->blockptrs[parent_slot] !=
 170                        btrfs_header_blocknr(&leaf->header));
 171         }
 172         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 173                 struct btrfs_key cpukey;
 174                 btrfs_disk_key_to_cpu(&cpukey, &leaf->items[i + 1].key);
 175                 BUG_ON(comp_keys(&leaf->items[i].key,
 176                                  &cpukey) >= 0);
 177                 BUG_ON(leaf->items[i].offset != leaf->items[i + 1].offset +
 178                     leaf->items[i + 1].size);
 179                 if (i == 0) {
 180                         BUG_ON(leaf->items[i].offset + leaf->items[i].size !=
 181                                 LEAF_DATA_SIZE);
 182                 }
 183         }
 184         return 0;
 185 }
 186
 187 int check_block(struct ctree_path *path, int level)
 188 {
 189         if (level == 0)
 190                 return check_leaf(path, level);
 191         return check_node(path, level);
 192 }
 193
 194 /*
 195  * search for key in the array p.  items p are item_size apart
 196  * and there are 'max' items in p
 197  * the slot in the array is returned via slot, and it points to
 198  * the place where you would insert key if it is not found in
 199  * the array.
 200  *
 201  * slot may point to max if the key is bigger than all of the keys
 202  */
 203 int generic_bin_search(char *p, int item_size, struct btrfs_key *key,
 204                        int max, int *slot)
 205 {
 206         int low = 0;
 207         int high = max;
 208         int mid;
 209         int ret;
 210         struct btrfs_disk_key *tmp;
 211
 212         while(low < high) {
 213                 mid = (low + high) / 2;
 214                 tmp = (struct btrfs_disk_key *)(p + mid * item_size);
 215                 ret = comp_keys(tmp, key);
 216
 217                 if (ret < 0)
 218                         low = mid + 1;
 219                 else if (ret > 0)
 220                         high = mid;
 221                 else {
 222                         *slot = mid;
 223                         return 0;
 224                 }
 225         }
 226         *slot = low;
 227         return 1;
 228 }
 229
 230 /*
 231  * simple bin_search frontend that does the right thing for
 232  * leaves vs nodes
 233  */
 234 int bin_search(struct node *c, struct btrfs_key *key, int *slot)
 235 {
 236         if (btrfs_is_leaf(c)) {
 237                 struct leaf *l = (struct leaf *)c;
 238                 return generic_bin_search((void *)l->items, sizeof(struct item),
 239                                           key, btrfs_header_nritems(&c->header),
 240                                           slot);
 241         } else {
 242                 return generic_bin_search((void *)c->keys,
 243                                           sizeof(struct btrfs_disk_key),
 244                                           key, btrfs_header_nritems(&c->header),
 245                                           slot);
 246         }
 247         return -1;
 248 }
 249
 250 struct tree_buffer *read_node_slot(struct ctree_root *root,
 251                                    struct tree_buffer *parent_buf,
 252                                    int slot)
 253 {
 254         struct node *node = &parent_buf->node;
 255         if (slot < 0)
 256                 return NULL;
 257         if (slot >= btrfs_header_nritems(&node->header))
 258                 return NULL;
 259         return read_tree_block(root, node->blockptrs[slot]);
 260 }
 261
 262 static int balance_level(struct ctree_root *root, struct ctree_path *path,
 263                         int level)
 264 {
 265         struct tree_buffer *right_buf;
 266         struct tree_buffer *mid_buf;
 267         struct tree_buffer *left_buf;
 268         struct tree_buffer *parent_buf = NULL;
 269         struct node *right = NULL;
 270         struct node *mid;
 271         struct node *left = NULL;
 272         struct node *parent = NULL;
 273         int ret = 0;
 274         int wret;
 275         int pslot;
 276         int orig_slot = path->slots[level];
 277         u64 orig_ptr;
 278
 279         if (level == 0)
 280                 return 0;
 281
 282         mid_buf = path->nodes[level];
 283         mid = &mid_buf->node;
 284         orig_ptr = mid->blockptrs[orig_slot];
 285
 286         if (level < MAX_LEVEL - 1)
 287                 parent_buf = path->nodes[level + 1];
 288         pslot = path->slots[level + 1];
 289
 290         if (!parent_buf) {
 291                 struct tree_buffer *child;
 292                 u64 blocknr = mid_buf->blocknr;
 293
 294                 if (btrfs_header_nritems(&mid->header) != 1)
 295                         return 0;
 296
 297                 /* promote the child to a root */
 298                 child = read_node_slot(root, mid_buf, 0);
 299                 BUG_ON(!child);
 300                 root->node = child;
 301                 path->nodes[level] = NULL;
 302                 /* once for the path */
 303                 tree_block_release(root, mid_buf);
 304                 /* once for the root ptr */
 305                 tree_block_release(root, mid_buf);
 306                 clean_tree_block(root, mid_buf);
 307                 return free_extent(root, blocknr, 1);
 308         }
 309         parent = &parent_buf->node;
 310
 311         if (btrfs_header_nritems(&mid->header) > NODEPTRS_PER_BLOCK / 4)
 312                 return 0;
 313
 314         left_buf = read_node_slot(root, parent_buf, pslot - 1);
 315         right_buf = read_node_slot(root, parent_buf, pslot + 1);
 316
 317         /* first, try to make some room in the middle buffer */
 318         if (left_buf) {
 319                 btrfs_cow_block(root, left_buf, parent_buf,
 320                                 pslot - 1, &left_buf);
 321                 left = &left_buf->node;
 322                 orig_slot += btrfs_header_nritems(&left->header);
 323                 wret = push_node_left(root, left_buf, mid_buf);
 324                 if (wret < 0)
 325                         ret = wret;
 326         }
 327
 328         /*
 329          * then try to empty the right most buffer into the middle
 330          */
 331         if (right_buf) {
 332                 btrfs_cow_block(root, right_buf, parent_buf,
 333                                 pslot + 1, &right_buf);
 334                 right = &right_buf->node;
 335                 wret = push_node_left(root, mid_buf, right_buf);
 336                 if (wret < 0)
 337                         ret = wret;
 338                 if (btrfs_header_nritems(&right->header) == 0) {
 339                         u64 blocknr = right_buf->blocknr;
 340                         tree_block_release(root, right_buf);
 341                         clean_tree_block(root, right_buf);
 342                         right_buf = NULL;
 343                         right = NULL;
 344                         wret = del_ptr(root, path, level + 1, pslot + 1);
 345                         if (wret)
 346                                 ret = wret;
 347                         wret = free_extent(root, blocknr, 1);
 348                         if (wret)
 349                                 ret = wret;
 350                 } else {
 351                         memcpy(parent->keys + pslot + 1, right->keys,
 352                                 sizeof(struct btrfs_disk_key));
 353                         BUG_ON(list_empty(&parent_buf->dirty));
 354                 }
 355         }
 356         if (btrfs_header_nritems(&mid->header) == 1) {
 357                 /*
 358                  * we're not allowed to leave a node with one item in the
 359                  * tree during a delete.  A deletion from lower in the tree
 360                  * could try to delete the only pointer in this node.
 361                  * So, pull some keys from the left.
 362                  * There has to be a left pointer at this point because
 363                  * otherwise we would have pulled some pointers from the
 364                  * right
 365                  */
 366                 BUG_ON(!left_buf);
 367                 wret = balance_node_right(root, mid_buf, left_buf);
 368                 if (wret < 0)
 369                         ret = wret;
 370                 BUG_ON(wret == 1);
 371         }
 372         if (btrfs_header_nritems(&mid->header) == 0) {
 373                 /* we've managed to empty the middle node, drop it */
 374                 u64 blocknr = mid_buf->blocknr;
 375                 tree_block_release(root, mid_buf);
 376                 clean_tree_block(root, mid_buf);
 377                 mid_buf = NULL;
 378                 mid = NULL;
 379                 wret = del_ptr(root, path, level + 1, pslot);
 380                 if (wret)
 381                         ret = wret;
 382                 wret = free_extent(root, blocknr, 1);
 383                 if (wret)
 384                         ret = wret;
 385         } else {
 386                 /* update the parent key to reflect our changes */
 387                 memcpy(parent->keys + pslot, mid->keys,
 388                        sizeof(struct btrfs_disk_key));
 389                 BUG_ON(list_empty(&parent_buf->dirty));
 390         }
 391
 392         /* update the path */
 393         if (left_buf) {
 394                 if (btrfs_header_nritems(&left->header) > orig_slot) {
 395                         left_buf->count++; // released below
 396                         path->nodes[level] = left_buf;
 397                         path->slots[level + 1] -= 1;
 398                         path->slots[level] = orig_slot;
 399                         if (mid_buf)
 400                                 tree_block_release(root, mid_buf);
 401                 } else {
 402                         orig_slot -= btrfs_header_nritems(&left->header);
 403                         path->slots[level] = orig_slot;
 404                 }
 405         }
 406         /* double check we haven't messed things up */
 407         check_block(path, level);
 408         if (orig_ptr != path->nodes[level]->node.blockptrs[path->slots[level]])
 409                 BUG();
 410
 411         if (right_buf)
 412                 tree_block_release(root, right_buf);
 413         if (left_buf)
 414                 tree_block_release(root, left_buf);
 415         return ret;
 416 }
 417
 418 /*
 419  * look for key in the tree.  path is filled in with nodes along the way
 420  * if key is found, we return zero and you can find the item in the leaf
 421  * level of the path (level 0)
 422  *
 423  * If the key isn't found, the path points to the slot where it should
 424  * be inserted, and 1 is returned.  If there are other errors during the
 425  * search a negative error number is returned.
 426  *
 427  * if ins_len > 0, nodes and leaves will be split as we walk down the
 428  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
 429  * possible)
 430  */
 431 int search_slot(struct ctree_root *root, struct btrfs_key *key,
 432                 struct ctree_path *p, int ins_len, int cow)
 433 {
 434         struct tree_buffer *b;
 435         struct tree_buffer *cow_buf;
 436         struct node *c;
 437         int slot;
 438         int ret;
 439         int level;
 440
 441 again:
 442         b = root->node;
 443         b->count++;
 444         while (b) {
 445                 level = btrfs_header_level(&b->node.header);
 446                 if (cow) {
 447                         int wret;
 448                         wret = btrfs_cow_block(root, b, p->nodes[level + 1],
 449                                                p->slots[level + 1], &cow_buf);
 450                         b = cow_buf;
 451                 }
 452                 BUG_ON(!cow && ins_len);
 453                 c = &b->node;
 454                 p->nodes[level] = b;
 455                 ret = check_block(p, level);
 456                 if (ret)
 457                         return -1;
 458                 ret = bin_search(c, key, &slot);
 459                 if (!btrfs_is_leaf(c)) {
 460                         if (ret && slot > 0)
 461                                 slot -= 1;
 462                         p->slots[level] = slot;
 463                         if (ins_len > 0 && btrfs_header_nritems(&c->header) ==
 464                             NODEPTRS_PER_BLOCK) {
 465                                 int sret = split_node(root, p, level);
 466                                 BUG_ON(sret > 0);
 467                                 if (sret)
 468                                         return sret;
 469                                 b = p->nodes[level];
 470                                 c = &b->node;
 471                                 slot = p->slots[level];
 472                         } else if (ins_len < 0) {
 473                                 int sret = balance_level(root, p, level);
 474                                 if (sret)
 475                                         return sret;
 476                                 b = p->nodes[level];
 477                                 if (!b)
 478                                         goto again;
 479                                 c = &b->node;
 480                                 slot = p->slots[level];
 481                                 BUG_ON(btrfs_header_nritems(&c->header) == 1);
 482                         }
 483                         b = read_tree_block(root, c->blockptrs[slot]);
 484                 } else {
 485                         struct leaf *l = (struct leaf *)c;
 486                         p->slots[level] = slot;
 487                         if (ins_len > 0 && leaf_free_space(l) <
 488                             sizeof(struct item) + ins_len) {
 489                                 int sret = split_leaf(root, p, ins_len);
 490                                 BUG_ON(sret > 0);
 491                                 if (sret)
 492                                         return sret;
 493                         }
 494                         BUG_ON(root->node->count == 1);
 495                         return ret;
 496                 }
 497         }
 498         BUG_ON(root->node->count == 1);
 499         return 1;
 500 }
 501
 502 /*
 503  * adjust the pointers going up the tree, starting at level
 504  * making sure the right key of each node is points to 'key'.
 505  * This is used after shifting pointers to the left, so it stops
 506  * fixing up pointers when a given leaf/node is not in slot 0 of the
 507  * higher levels
 508  *
 509  * If this fails to write a tree block, it returns -1, but continues
 510  * fixing up the blocks in ram so the tree is consistent.
 511  */
 512 static int fixup_low_keys(struct ctree_root *root,
 513                            struct ctree_path *path, struct btrfs_disk_key *key,
 514                            int level)
 515 {
 516         int i;
 517         int ret = 0;
 518         for (i = level; i < MAX_LEVEL; i++) {
 519                 struct node *t;
 520                 int tslot = path->slots[i];
 521                 if (!path->nodes[i])
 522                         break;
 523                 t = &path->nodes[i]->node;
 524                 memcpy(t->keys + tslot, key, sizeof(*key));
 525                 BUG_ON(list_empty(&path->nodes[i]->dirty));
 526                 if (tslot != 0)
 527                         break;
 528         }
 529         return ret;
 530 }
 531
 532 /*
 533  * try to push data from one node into the next node left in the
 534  * tree.
 535  *
 536  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
 537  * error, and > 0 if there was no room in the left hand block.
 538  */
 539 static int push_node_left(struct ctree_root *root, struct tree_buffer *dst_buf,
 540                           struct tree_buffer *src_buf)
 541 {
 542         struct node *src = &src_buf->node;
 543         struct node *dst = &dst_buf->node;
 544         int push_items = 0;
 545         int src_nritems;
 546         int dst_nritems;
 547         int ret = 0;
 548
 549         src_nritems = btrfs_header_nritems(&src->header);
 550         dst_nritems = btrfs_header_nritems(&dst->header);
 551         push_items = NODEPTRS_PER_BLOCK - dst_nritems;
 552         if (push_items <= 0) {
 553                 return 1;
 554         }
 555
 556         if (src_nritems < push_items)
 557                 push_items = src_nritems;
 558
 559         memcpy(dst->keys + dst_nritems, src->keys,
 560                 push_items * sizeof(struct btrfs_disk_key));
 561         memcpy(dst->blockptrs + dst_nritems, src->blockptrs,
 562                 push_items * sizeof(u64));
 563         if (push_items < src_nritems) {
 564                 memmove(src->keys, src->keys + push_items,
 565                         (src_nritems - push_items) *
 566                         sizeof(struct btrfs_disk_key));
 567                 memmove(src->blockptrs, src->blockptrs + push_items,
 568                         (src_nritems - push_items) * sizeof(u64));
 569         }
 570         btrfs_set_header_nritems(&src->header, src_nritems - push_items);
 571         btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
 572         BUG_ON(list_empty(&src_buf->dirty));
 573         BUG_ON(list_empty(&dst_buf->dirty));
 574         return ret;
 575 }
 576
 577 /*
 578  * try to push data from one node into the next node right in the
 579  * tree.
 580  *
 581  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
 582  * error, and > 0 if there was no room in the right hand block.
 583  *
 584  * this will  only push up to 1/2 the contents of the left node over
 585  */
 586 static int balance_node_right(struct ctree_root *root,
 587                               struct tree_buffer *dst_buf,
 588                               struct tree_buffer *src_buf)
 589 {
 590         struct node *src = &src_buf->node;
 591         struct node *dst = &dst_buf->node;
 592         int push_items = 0;
 593         int max_push;
 594         int src_nritems;
 595         int dst_nritems;
 596         int ret = 0;
 597
 598         src_nritems = btrfs_header_nritems(&src->header);
 599         dst_nritems = btrfs_header_nritems(&dst->header);
 600         push_items = NODEPTRS_PER_BLOCK - dst_nritems;
 601         if (push_items <= 0) {
 602                 return 1;
 603         }
 604
 605         max_push = src_nritems / 2 + 1;
 606         /* don't try to empty the node */
 607         if (max_push > src_nritems)
 608                 return 1;
 609         if (max_push < push_items)
 610                 push_items = max_push;
 611
 612         memmove(dst->keys + push_items, dst->keys,
 613                 dst_nritems * sizeof(struct btrfs_disk_key));
 614         memmove(dst->blockptrs + push_items, dst->blockptrs,
 615                 dst_nritems * sizeof(u64));
 616         memcpy(dst->keys, src->keys + src_nritems - push_items,
 617                 push_items * sizeof(struct btrfs_disk_key));
 618         memcpy(dst->blockptrs, src->blockptrs + src_nritems - push_items,
 619                 push_items * sizeof(u64));
 620
 621         btrfs_set_header_nritems(&src->header, src_nritems - push_items);
 622         btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
 623
 624         BUG_ON(list_empty(&src_buf->dirty));
 625         BUG_ON(list_empty(&dst_buf->dirty));
 626         return ret;
 627 }
 628
 629 /*
 630  * helper function to insert a new root level in the tree.
 631  * A new node is allocated, and a single item is inserted to
 632  * point to the existing root
 633  *
 634  * returns zero on success or < 0 on failure.
 635  */
 636 static int insert_new_root(struct ctree_root *root,
 637                            struct ctree_path *path, int level)
 638 {
 639         struct tree_buffer *t;
 640         struct node *lower;
 641         struct node *c;
 642         struct btrfs_disk_key *lower_key;
 643
 644         BUG_ON(path->nodes[level]);
 645         BUG_ON(path->nodes[level-1] != root->node);
 646
 647         t = alloc_free_block(root);
 648         c = &t->node;
 649         memset(c, 0, sizeof(c));
 650         btrfs_set_header_nritems(&c->header, 1);
 651         btrfs_set_header_level(&c->header, level);
 652         btrfs_set_header_blocknr(&c->header, t->blocknr);
 653         btrfs_set_header_parentid(&c->header,
 654                                btrfs_header_parentid(&root->node->node.header));
 655         lower = &path->nodes[level-1]->node;
 656         if (btrfs_is_leaf(lower))
 657                 lower_key = &((struct leaf *)lower)->items[0].key;
 658         else
 659                 lower_key = lower->keys;
 660         memcpy(c->keys, lower_key, sizeof(struct btrfs_disk_key));
 661         c->blockptrs[0] = path->nodes[level-1]->blocknr;
 662         /* the super has an extra ref to root->node */
 663         tree_block_release(root, root->node);
 664         root->node = t;
 665         t->count++;
 666         path->nodes[level] = t;
 667         path->slots[level] = 0;
 668         return 0;
 669 }
 670
 671 /*
 672  * worker function to insert a single pointer in a node.
 673  * the node should have enough room for the pointer already
 674  *
 675  * slot and level indicate where you want the key to go, and
 676  * blocknr is the block the key points to.
 677  *
 678  * returns zero on success and < 0 on any error
 679  */
 680 static int insert_ptr(struct ctree_root *root,
 681                 struct ctree_path *path, struct btrfs_disk_key *key,
 682                 u64 blocknr, int slot, int level)
 683 {
 684         struct node *lower;
 685         int nritems;
 686
 687         BUG_ON(!path->nodes[level]);
 688         lower = &path->nodes[level]->node;
 689         nritems = btrfs_header_nritems(&lower->header);
 690         if (slot > nritems)
 691                 BUG();
 692         if (nritems == NODEPTRS_PER_BLOCK)
 693                 BUG();
 694         if (slot != nritems) {
 695                 memmove(lower->keys + slot + 1, lower->keys + slot,
 696                         (nritems - slot) * sizeof(struct btrfs_disk_key));
 697                 memmove(lower->blockptrs + slot + 1, lower->blockptrs + slot,
 698                         (nritems - slot) * sizeof(u64));
 699         }
 700         memcpy(lower->keys + slot, key, sizeof(struct btrfs_disk_key));
 701         lower->blockptrs[slot] = blocknr;
 702         btrfs_set_header_nritems(&lower->header, nritems + 1);
 703         if (lower->keys[1].objectid == 0)
 704                         BUG();
 705         BUG_ON(list_empty(&path->nodes[level]->dirty));
 706         return 0;
 707 }
 708
 709 /*
 710  * split the node at the specified level in path in two.
 711  * The path is corrected to point to the appropriate node after the split
 712  *
 713  * Before splitting this tries to make some room in the node by pushing
 714  * left and right, if either one works, it returns right away.
 715  *
 716  * returns 0 on success and < 0 on failure
 717  */
 718 static int split_node(struct ctree_root *root, struct ctree_path *path,
 719                       int level)
 720 {
 721         struct tree_buffer *t;
 722         struct node *c;
 723         struct tree_buffer *split_buffer;
 724         struct node *split;
 725         int mid;
 726         int ret;
 727         int wret;
 728         u32 c_nritems;
 729
 730         t = path->nodes[level];
 731         c = &t->node;
 732         if (t == root->node) {
 733                 /* trying to split the root, lets make a new one */
 734                 ret = insert_new_root(root, path, level + 1);
 735                 if (ret)
 736                         return ret;
 737         }
 738         c_nritems = btrfs_header_nritems(&c->header);
 739         split_buffer = alloc_free_block(root);
 740         split = &split_buffer->node;
 741         btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
 742         btrfs_set_header_blocknr(&split->header, split_buffer->blocknr);
 743         btrfs_set_header_parentid(&split->header,
 744                                btrfs_header_parentid(&root->node->node.header));
 745         mid = (c_nritems + 1) / 2;
 746         memcpy(split->keys, c->keys + mid,
 747                 (c_nritems - mid) * sizeof(struct btrfs_disk_key));
 748         memcpy(split->blockptrs, c->blockptrs + mid,
 749                 (c_nritems - mid) * sizeof(u64));
 750         btrfs_set_header_nritems(&split->header, c_nritems - mid);
 751         btrfs_set_header_nritems(&c->header, mid);
 752         ret = 0;
 753
 754         BUG_ON(list_empty(&t->dirty));
 755         wret = insert_ptr(root, path, split->keys, split_buffer->blocknr,
 756                           path->slots[level + 1] + 1, level + 1);
 757         if (wret)
 758                 ret = wret;
 759
 760         if (path->slots[level] >= mid) {
 761                 path->slots[level] -= mid;
 762                 tree_block_release(root, t);
 763                 path->nodes[level] = split_buffer;
 764                 path->slots[level + 1] += 1;
 765         } else {
 766                 tree_block_release(root, split_buffer);
 767         }
 768         return ret;
 769 }
 770
 771 /*
 772  * how many bytes are required to store the items in a leaf.  start
 773  * and nr indicate which items in the leaf to check.  This totals up the
 774  * space used both by the item structs and the item data
 775  */
 776 static int leaf_space_used(struct leaf *l, int start, int nr)
 777 {
 778         int data_len;
 779         int end = start + nr - 1;
 780
 781         if (!nr)
 782                 return 0;
 783         data_len = l->items[start].offset + l->items[start].size;
 784         data_len = data_len - l->items[end].offset;
 785         data_len += sizeof(struct item) * nr;
 786         return data_len;
 787 }
 788
 789 /*
 790  * push some data in the path leaf to the right, trying to free up at
 791  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
 792  *
 793  * returns 1 if the push failed because the other node didn't have enough
 794  * room, 0 if everything worked out and < 0 if there were major errors.
 795  */
 796 static int push_leaf_right(struct ctree_root *root, struct ctree_path *path,
 797                            int data_size)
 798 {
 799         struct tree_buffer *left_buf = path->nodes[0];
 800         struct leaf *left = &left_buf->leaf;
 801         struct leaf *right;
 802         struct tree_buffer *right_buf;
 803         struct tree_buffer *upper;
 804         int slot;
 805         int i;
 806         int free_space;
 807         int push_space = 0;
 808         int push_items = 0;
 809         struct item *item;
 810         u32 left_nritems;
 811         u32 right_nritems;
 812
 813         slot = path->slots[1];
 814         if (!path->nodes[1]) {
 815                 return 1;
 816         }
 817         upper = path->nodes[1];
 818         if (slot >= btrfs_header_nritems(&upper->node.header) - 1) {
 819                 return 1;
 820         }
 821         right_buf = read_tree_block(root, upper->node.blockptrs[slot + 1]);
 822         right = &right_buf->leaf;
 823         free_space = leaf_free_space(right);
 824         if (free_space < data_size + sizeof(struct item)) {
 825                 tree_block_release(root, right_buf);
 826                 return 1;
 827         }
 828         /* cow and double check */
 829         btrfs_cow_block(root, right_buf, upper, slot + 1, &right_buf);
 830         right = &right_buf->leaf;
 831         free_space = leaf_free_space(right);
 832         if (free_space < data_size + sizeof(struct item)) {
 833                 tree_block_release(root, right_buf);
 834                 return 1;
 835         }
 836
 837         left_nritems = btrfs_header_nritems(&left->header);
 838         for (i = left_nritems - 1; i >= 0; i--) {
 839                 item = left->items + i;
 840                 if (path->slots[0] == i)
 841                         push_space += data_size + sizeof(*item);
 842                 if (item->size + sizeof(*item) + push_space > free_space)
 843                         break;
 844                 push_items++;
 845                 push_space += item->size + sizeof(*item);
 846         }
 847         if (push_items == 0) {
 848                 tree_block_release(root, right_buf);
 849                 return 1;
 850         }
 851         right_nritems = btrfs_header_nritems(&right->header);
 852         /* push left to right */
 853         push_space = left->items[left_nritems - push_items].offset +
 854                      left->items[left_nritems - push_items].size;
 855         push_space -= leaf_data_end(left);
 856         /* make room in the right data area */
 857         memmove(right->data + leaf_data_end(right) - push_space,
 858                 right->data + leaf_data_end(right),
 859                 LEAF_DATA_SIZE - leaf_data_end(right));
 860         /* copy from the left data area */
 861         memcpy(right->data + LEAF_DATA_SIZE - push_space,
 862                 left->data + leaf_data_end(left),
 863                 push_space);
 864         memmove(right->items + push_items, right->items,
 865                 right_nritems * sizeof(struct item));
 866         /* copy the items from left to right */
 867         memcpy(right->items, left->items + left_nritems - push_items,
 868                 push_items * sizeof(struct item));
 869
 870         /* update the item pointers */
 871         right_nritems += push_items;
 872         btrfs_set_header_nritems(&right->header, right_nritems);
 873         push_space = LEAF_DATA_SIZE;
 874         for (i = 0; i < right_nritems; i++) {
 875                 right->items[i].offset = push_space - right->items[i].size;
 876                 push_space = right->items[i].offset;
 877         }
 878         left_nritems -= push_items;
 879         btrfs_set_header_nritems(&left->header, left_nritems);
 880
 881         BUG_ON(list_empty(&left_buf->dirty));
 882         BUG_ON(list_empty(&right_buf->dirty));
 883         memcpy(upper->node.keys + slot + 1,
 884                 &right->items[0].key, sizeof(struct btrfs_disk_key));
 885         BUG_ON(list_empty(&upper->dirty));
 886
 887         /* then fixup the leaf pointer in the path */
 888         if (path->slots[0] >= left_nritems) {
 889                 path->slots[0] -= left_nritems;
 890                 tree_block_release(root, path->nodes[0]);
 891                 path->nodes[0] = right_buf;
 892                 path->slots[1] += 1;
 893         } else {
 894                 tree_block_release(root, right_buf);
 895         }
 896         return 0;
 897 }
 898 /*
 899  * push some data in the path leaf to the left, trying to free up at
 900  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
 901  */
 902 static int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
 903                           int data_size)
 904 {
 905         struct tree_buffer *right_buf = path->nodes[0];
 906         struct leaf *right = &right_buf->leaf;
 907         struct tree_buffer *t;
 908         struct leaf *left;
 909         int slot;
 910         int i;
 911         int free_space;
 912         int push_space = 0;
 913         int push_items = 0;
 914         struct item *item;
 915         u32 old_left_nritems;
 916         int ret = 0;
 917         int wret;
 918
 919         slot = path->slots[1];
 920         if (slot == 0) {
 921                 return 1;
 922         }
 923         if (!path->nodes[1]) {
 924                 return 1;
 925         }
 926         t = read_tree_block(root, path->nodes[1]->node.blockptrs[slot - 1]);
 927         left = &t->leaf;
 928         free_space = leaf_free_space(left);
 929         if (free_space < data_size + sizeof(struct item)) {
 930                 tree_block_release(root, t);
 931                 return 1;
 932         }
 933
 934         /* cow and double check */
 935         btrfs_cow_block(root, t, path->nodes[1], slot - 1, &t);
 936         left = &t->leaf;
 937         free_space = leaf_free_space(left);
 938         if (free_space < data_size + sizeof(struct item)) {
 939                 tree_block_release(root, t);
 940                 return 1;
 941         }
 942
 943         for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
 944                 item = right->items + i;
 945                 if (path->slots[0] == i)
 946                         push_space += data_size + sizeof(*item);
 947                 if (item->size + sizeof(*item) + push_space > free_space)
 948                         break;
 949                 push_items++;
 950                 push_space += item->size + sizeof(*item);
 951         }
 952         if (push_items == 0) {
 953                 tree_block_release(root, t);
 954                 return 1;
 955         }
 956         /* push data from right to left */
 957         memcpy(left->items + btrfs_header_nritems(&left->header),
 958                 right->items, push_items * sizeof(struct item));
 959         push_space = LEAF_DATA_SIZE - right->items[push_items -1].offset;
 960         memcpy(left->data + leaf_data_end(left) - push_space,
 961                 right->data + right->items[push_items - 1].offset,
 962                 push_space);
 963         old_left_nritems = btrfs_header_nritems(&left->header);
 964         BUG_ON(old_left_nritems < 0);
 965
 966         for(i = old_left_nritems; i < old_left_nritems + push_items; i++) {
 967                 left->items[i].offset -= LEAF_DATA_SIZE -
 968                         left->items[old_left_nritems -1].offset;
 969         }
 970         btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
 971
 972         /* fixup right node */
 973         push_space = right->items[push_items-1].offset - leaf_data_end(right);
 974         memmove(right->data + LEAF_DATA_SIZE - push_space, right->data +
 975                 leaf_data_end(right), push_space);
 976         memmove(right->items, right->items + push_items,
 977                 (btrfs_header_nritems(&right->header) - push_items) *
 978                 sizeof(struct item));
 979         btrfs_set_header_nritems(&right->header,
 980                                  btrfs_header_nritems(&right->header) -
 981                                  push_items);
 982         push_space = LEAF_DATA_SIZE;
 983
 984         for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
 985                 right->items[i].offset = push_space - right->items[i].size;
 986                 push_space = right->items[i].offset;
 987         }
 988
 989         BUG_ON(list_empty(&t->dirty));
 990         BUG_ON(list_empty(&right_buf->dirty));
 991
 992         wret = fixup_low_keys(root, path, &right->items[0].key, 1);
 993         if (wret)
 994                 ret = wret;
 995
 996         /* then fixup the leaf pointer in the path */
 997         if (path->slots[0] < push_items) {
 998                 path->slots[0] += old_left_nritems;
 999                 tree_block_release(root, path->nodes[0]);
1000                 path->nodes[0] = t;
1001                 path->slots[1] -= 1;
1002         } else {
1003                 tree_block_release(root, t);
1004                 path->slots[0] -= push_items;
1005         }
1006         BUG_ON(path->slots[0] < 0);
1007         return ret;
1008 }
1009
1010 /*
1011  * split the path's leaf in two, making sure there is at least data_size
1012  * available for the resulting leaf level of the path.
1013  *
1014  * returns 0 if all went well and < 0 on failure.
1015  */
1016 static int split_leaf(struct ctree_root *root, struct ctree_path *path,
1017                       int data_size)
1018 {
1019         struct tree_buffer *l_buf;
1020         struct leaf *l;
1021         u32 nritems;
1022         int mid;
1023         int slot;
1024         struct leaf *right;
1025         struct tree_buffer *right_buffer;
1026         int space_needed = data_size + sizeof(struct item);
1027         int data_copy_size;
1028         int rt_data_off;
1029         int i;
1030         int ret;
1031         int wret;
1032
1033         l_buf = path->nodes[0];
1034         l = &l_buf->leaf;
1035
1036         /* did the pushes work? */
1037         if (leaf_free_space(l) >= sizeof(struct item) + data_size)
1038                 return 0;
1039
1040         if (!path->nodes[1]) {
1041                 ret = insert_new_root(root, path, 1);
1042                 if (ret)
1043                         return ret;
1044         }
1045         slot = path->slots[0];
1046         nritems = btrfs_header_nritems(&l->header);
1047         mid = (nritems + 1)/ 2;
1048         right_buffer = alloc_free_block(root);
1049         BUG_ON(!right_buffer);
1050         BUG_ON(mid == nritems);
1051         right = &right_buffer->leaf;
1052         memset(right, 0, sizeof(*right));
1053         if (mid <= slot) {
1054                 /* FIXME, just alloc a new leaf here */
1055                 if (leaf_space_used(l, mid, nritems - mid) + space_needed >
1056                         LEAF_DATA_SIZE)
1057                         BUG();
1058         } else {
1059                 /* FIXME, just alloc a new leaf here */
1060                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1061                         LEAF_DATA_SIZE)
1062                         BUG();
1063         }
1064         btrfs_set_header_nritems(&right->header, nritems - mid);
1065         btrfs_set_header_blocknr(&right->header, right_buffer->blocknr);
1066         btrfs_set_header_level(&right->header, 0);
1067         btrfs_set_header_parentid(&right->header,
1068                                btrfs_header_parentid(&root->node->node.header));
1069         data_copy_size = l->items[mid].offset + l->items[mid].size -
1070                          leaf_data_end(l);
1071         memcpy(right->items, l->items + mid,
1072                (nritems - mid) * sizeof(struct item));
1073         memcpy(right->data + LEAF_DATA_SIZE - data_copy_size,
1074                l->data + leaf_data_end(l), data_copy_size);
1075         rt_data_off = LEAF_DATA_SIZE -
1076                      (l->items[mid].offset + l->items[mid].size);
1077
1078         for (i = 0; i < btrfs_header_nritems(&right->header); i++)
1079                 right->items[i].offset += rt_data_off;
1080
1081         btrfs_set_header_nritems(&l->header, mid);
1082         ret = 0;
1083         wret = insert_ptr(root, path, &right->items[0].key,
1084                           right_buffer->blocknr, path->slots[1] + 1, 1);
1085         if (wret)
1086                 ret = wret;
1087         BUG_ON(list_empty(&right_buffer->dirty));
1088         BUG_ON(list_empty(&l_buf->dirty));
1089         BUG_ON(path->slots[0] != slot);
1090         if (mid <= slot) {
1091                 tree_block_release(root, path->nodes[0]);
1092                 path->nodes[0] = right_buffer;
1093                 path->slots[0] -= mid;
1094                 path->slots[1] += 1;
1095         } else
1096                 tree_block_release(root, right_buffer);
1097         BUG_ON(path->slots[0] < 0);
1098         return ret;
1099 }
1100
1101 /*
1102  * Given a key and some data, insert an item into the tree.
1103  * This does all the path init required, making room in the tree if needed.
1104  */
1105 int insert_item(struct ctree_root *root, struct btrfs_key *cpu_key,
1106                           void *data, int data_size)
1107 {
1108         int ret = 0;
1109         int slot;
1110         int slot_orig;
1111         struct leaf *leaf;
1112         struct tree_buffer *leaf_buf;
1113         u32 nritems;
1114         unsigned int data_end;
1115         struct ctree_path path;
1116         struct btrfs_disk_key disk_key;
1117
1118         btrfs_cpu_key_to_disk(&disk_key, cpu_key);
1119
1120         /* create a root if there isn't one */
1121         if (!root->node)
1122                 BUG();
1123         init_path(&path);
1124         ret = search_slot(root, cpu_key, &path, data_size, 1);
1125         if (ret == 0) {
1126                 release_path(root, &path);
1127                 return -EEXIST;
1128         }
1129         if (ret < 0)
1130                 goto out;
1131
1132         slot_orig = path.slots[0];
1133         leaf_buf = path.nodes[0];
1134         leaf = &leaf_buf->leaf;
1135
1136         nritems = btrfs_header_nritems(&leaf->header);
1137         data_end = leaf_data_end(leaf);
1138
1139         if (leaf_free_space(leaf) <  sizeof(struct item) + data_size)
1140                 BUG();
1141
1142         slot = path.slots[0];
1143         BUG_ON(slot < 0);
1144         if (slot != nritems) {
1145                 int i;
1146                 unsigned int old_data = leaf->items[slot].offset +
1147                                         leaf->items[slot].size;
1148
1149                 /*
1150                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
1151                  */
1152                 /* first correct the data pointers */
1153                 for (i = slot; i < nritems; i++)
1154                         leaf->items[i].offset -= data_size;
1155
1156                 /* shift the items */
1157                 memmove(leaf->items + slot + 1, leaf->items + slot,
1158                         (nritems - slot) * sizeof(struct item));
1159
1160                 /* shift the data */
1161                 memmove(leaf->data + data_end - data_size, leaf->data +
1162                         data_end, old_data - data_end);
1163                 data_end = old_data;
1164         }
1165         /* copy the new data in */
1166         memcpy(&leaf->items[slot].key, &disk_key,
1167                 sizeof(struct btrfs_disk_key));
1168         leaf->items[slot].offset = data_end - data_size;
1169         leaf->items[slot].size = data_size;
1170         memcpy(leaf->data + data_end - data_size, data, data_size);
1171         btrfs_set_header_nritems(&leaf->header, nritems + 1);
1172
1173         ret = 0;
1174         if (slot == 0)
1175                 ret = fixup_low_keys(root, &path, &disk_key, 1);
1176
1177         BUG_ON(list_empty(&leaf_buf->dirty));
1178         if (leaf_free_space(leaf) < 0)
1179                 BUG();
1180         check_leaf(&path, 0);
1181 out:
1182         release_path(root, &path);
1183         return ret;
1184 }
1185
1186 /*
1187  * delete the pointer from a given node.
1188  *
1189  * If the delete empties a node, the node is removed from the tree,
1190  * continuing all the way the root if required.  The root is converted into
1191  * a leaf if all the nodes are emptied.
1192  */
1193 static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
1194                    int slot)
1195 {
1196         struct node *node;
1197         struct tree_buffer *parent = path->nodes[level];
1198         u32 nritems;
1199         int ret = 0;
1200         int wret;
1201
1202         node = &parent->node;
1203         nritems = btrfs_header_nritems(&node->header);
1204         if (slot != nritems -1) {
1205                 memmove(node->keys + slot, node->keys + slot + 1,
1206                         sizeof(struct btrfs_disk_key) * (nritems - slot - 1));
1207                 memmove(node->blockptrs + slot,
1208                         node->blockptrs + slot + 1,
1209                         sizeof(u64) * (nritems - slot - 1));
1210         }
1211         nritems--;
1212         btrfs_set_header_nritems(&node->header, nritems);
1213         if (nritems == 0 && parent == root->node) {
1214                 BUG_ON(btrfs_header_level(&root->node->node.header) != 1);
1215                 /* just turn the root into a leaf and break */
1216                 btrfs_set_header_level(&root->node->node.header, 0);
1217         } else if (slot == 0) {
1218                 wret = fixup_low_keys(root, path, node->keys, level + 1);
1219                 if (wret)
1220                         ret = wret;
1221         }
1222         BUG_ON(list_empty(&parent->dirty));
1223         return ret;
1224 }
1225
1226 /*
1227  * delete the item at the leaf level in path.  If that empties
1228  * the leaf, remove it from the tree
1229  */
1230 int del_item(struct ctree_root *root, struct ctree_path *path)
1231 {
1232         int slot;
1233         struct leaf *leaf;
1234         struct tree_buffer *leaf_buf;
1235         int doff;
1236         int dsize;
1237         int ret = 0;
1238         int wret;
1239         u32 nritems;
1240
1241         leaf_buf = path->nodes[0];
1242         leaf = &leaf_buf->leaf;
1243         slot = path->slots[0];
1244         doff = leaf->items[slot].offset;
1245         dsize = leaf->items[slot].size;
1246         nritems = btrfs_header_nritems(&leaf->header);
1247
1248         if (slot != nritems - 1) {
1249                 int i;
1250                 int data_end = leaf_data_end(leaf);
1251                 memmove(leaf->data + data_end + dsize,
1252                         leaf->data + data_end,
1253                         doff - data_end);
1254                 for (i = slot + 1; i < nritems; i++)
1255                         leaf->items[i].offset += dsize;
1256                 memmove(leaf->items + slot, leaf->items + slot + 1,
1257                         sizeof(struct item) *
1258                         (nritems - slot - 1));
1259         }
1260         btrfs_set_header_nritems(&leaf->header, nritems - 1);
1261         nritems--;
1262         /* delete the leaf if we've emptied it */
1263         if (nritems == 0) {
1264                 if (leaf_buf == root->node) {
1265                         btrfs_set_header_level(&leaf->header, 0);
1266                         BUG_ON(list_empty(&leaf_buf->dirty));
1267                 } else {
1268                         clean_tree_block(root, leaf_buf);
1269                         wret = del_ptr(root, path, 1, path->slots[1]);
1270                         if (wret)
1271                                 ret = wret;
1272                         wret = free_extent(root, leaf_buf->blocknr, 1);
1273                         if (wret)
1274                                 ret = wret;
1275                 }
1276         } else {
1277                 int used = leaf_space_used(leaf, 0, nritems);
1278                 if (slot == 0) {
1279                         wret = fixup_low_keys(root, path,
1280                                                    &leaf->items[0].key, 1);
1281                         if (wret)
1282                                 ret = wret;
1283                 }
1284                 BUG_ON(list_empty(&leaf_buf->dirty));
1285
1286                 /* delete the leaf if it is mostly empty */
1287                 if (used < LEAF_DATA_SIZE / 3) {
1288                         /* push_leaf_left fixes the path.
1289                          * make sure the path still points to our leaf
1290                          * for possible call to del_ptr below
1291                          */
1292                         slot = path->slots[1];
1293                         leaf_buf->count++;
1294                         wret = push_leaf_left(root, path, 1);
1295                         if (wret < 0)
1296                                 ret = wret;
1297                         if (path->nodes[0] == leaf_buf &&
1298                             btrfs_header_nritems(&leaf->header)) {
1299                                 wret = push_leaf_right(root, path, 1);
1300                                 if (wret < 0)
1301                                         ret = wret;
1302                         }
1303                         if (btrfs_header_nritems(&leaf->header) == 0) {
1304                                 u64 blocknr = leaf_buf->blocknr;
1305                                 clean_tree_block(root, leaf_buf);
1306                                 wret = del_ptr(root, path, 1, slot);
1307                                 if (wret)
1308                                         ret = wret;
1309                                 tree_block_release(root, leaf_buf);
1310                                 wret = free_extent(root, blocknr, 1);
1311                                 if (wret)
1312                                         ret = wret;
1313                         } else {
1314                                 tree_block_release(root, leaf_buf);
1315                         }
1316                 }
1317         }
1318         return ret;
1319 }
1320
1321 /*
1322  * walk up the tree as far as required to find the next leaf.
1323  * returns 0 if it found something or 1 if there are no greater leaves.
1324  * returns < 0 on io errors.
1325  */
1326 int next_leaf(struct ctree_root *root, struct ctree_path *path)
1327 {
1328         int slot;
1329         int level = 1;
1330         u64 blocknr;
1331         struct tree_buffer *c;
1332         struct tree_buffer *next = NULL;
1333
1334         while(level < MAX_LEVEL) {
1335                 if (!path->nodes[level])
1336                         return 1;
1337                 slot = path->slots[level] + 1;
1338                 c = path->nodes[level];
1339                 if (slot >= btrfs_header_nritems(&c->node.header)) {
1340                         level++;
1341                         continue;
1342                 }
1343                 blocknr = c->node.blockptrs[slot];
1344                 if (next)
1345                         tree_block_release(root, next);
1346                 next = read_tree_block(root, blocknr);
1347                 break;
1348         }
1349         path->slots[level] = slot;
1350         while(1) {
1351                 level--;
1352                 c = path->nodes[level];
1353                 tree_block_release(root, c);
1354                 path->nodes[level] = next;
1355                 path->slots[level] = 0;
1356                 if (!level)
1357                         break;
1358                 next = read_tree_block(root, next->node.blockptrs[0]);
1359         }
1360         return 0;
1361 }
1362
1363