fs/btrfs/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 btrfs_item_offset(leaf->items + nr - 1);
  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(btrfs_item_offset(leaf->items + i) !=
 178                         btrfs_item_end(leaf->items + i + 1));
 179                 if (i == 0) {
 180                         BUG_ON(btrfs_item_offset(leaf->items + i) +
 181                                btrfs_item_size(leaf->items + i) !=
 182                                LEAF_DATA_SIZE);
 183                 }
 184         }
 185         return 0;
 186 }
 187
 188 int check_block(struct ctree_path *path, int level)
 189 {
 190         if (level == 0)
 191                 return check_leaf(path, level);
 192         return check_node(path, level);
 193 }
 194
 195 /*
 196  * search for key in the array p.  items p are item_size apart
 197  * and there are 'max' items in p
 198  * the slot in the array is returned via slot, and it points to
 199  * the place where you would insert key if it is not found in
 200  * the array.
 201  *
 202  * slot may point to max if the key is bigger than all of the keys
 203  */
 204 int generic_bin_search(char *p, int item_size, struct btrfs_key *key,
 205                        int max, int *slot)
 206 {
 207         int low = 0;
 208         int high = max;
 209         int mid;
 210         int ret;
 211         struct btrfs_disk_key *tmp;
 212
 213         while(low < high) {
 214                 mid = (low + high) / 2;
 215                 tmp = (struct btrfs_disk_key *)(p + mid * item_size);
 216                 ret = comp_keys(tmp, key);
 217
 218                 if (ret < 0)
 219                         low = mid + 1;
 220                 else if (ret > 0)
 221                         high = mid;
 222                 else {
 223                         *slot = mid;
 224                         return 0;
 225                 }
 226         }
 227         *slot = low;
 228         return 1;
 229 }
 230
 231 /*
 232  * simple bin_search frontend that does the right thing for
 233  * leaves vs nodes
 234  */
 235 int bin_search(struct node *c, struct btrfs_key *key, int *slot)
 236 {
 237         if (btrfs_is_leaf(c)) {
 238                 struct leaf *l = (struct leaf *)c;
 239                 return generic_bin_search((void *)l->items,
 240                                           sizeof(struct btrfs_item),
 241                                           key, btrfs_header_nritems(&c->header),
 242                                           slot);
 243         } else {
 244                 return generic_bin_search((void *)c->keys,
 245                                           sizeof(struct btrfs_disk_key),
 246                                           key, btrfs_header_nritems(&c->header),
 247                                           slot);
 248         }
 249         return -1;
 250 }
 251
 252 struct tree_buffer *read_node_slot(struct ctree_root *root,
 253                                    struct tree_buffer *parent_buf,
 254                                    int slot)
 255 {
 256         struct node *node = &parent_buf->node;
 257         if (slot < 0)
 258                 return NULL;
 259         if (slot >= btrfs_header_nritems(&node->header))
 260                 return NULL;
 261         return read_tree_block(root, node->blockptrs[slot]);
 262 }
 263
 264 static int balance_level(struct ctree_root *root, struct ctree_path *path,
 265                         int level)
 266 {
 267         struct tree_buffer *right_buf;
 268         struct tree_buffer *mid_buf;
 269         struct tree_buffer *left_buf;
 270         struct tree_buffer *parent_buf = NULL;
 271         struct node *right = NULL;
 272         struct node *mid;
 273         struct node *left = NULL;
 274         struct node *parent = NULL;
 275         int ret = 0;
 276         int wret;
 277         int pslot;
 278         int orig_slot = path->slots[level];
 279         u64 orig_ptr;
 280
 281         if (level == 0)
 282                 return 0;
 283
 284         mid_buf = path->nodes[level];
 285         mid = &mid_buf->node;
 286         orig_ptr = mid->blockptrs[orig_slot];
 287
 288         if (level < MAX_LEVEL - 1)
 289                 parent_buf = path->nodes[level + 1];
 290         pslot = path->slots[level + 1];
 291
 292         if (!parent_buf) {
 293                 struct tree_buffer *child;
 294                 u64 blocknr = mid_buf->blocknr;
 295
 296                 if (btrfs_header_nritems(&mid->header) != 1)
 297                         return 0;
 298
 299                 /* promote the child to a root */
 300                 child = read_node_slot(root, mid_buf, 0);
 301                 BUG_ON(!child);
 302                 root->node = child;
 303                 path->nodes[level] = NULL;
 304                 /* once for the path */
 305                 tree_block_release(root, mid_buf);
 306                 /* once for the root ptr */
 307                 tree_block_release(root, mid_buf);
 308                 clean_tree_block(root, mid_buf);
 309                 return free_extent(root, blocknr, 1);
 310         }
 311         parent = &parent_buf->node;
 312
 313         if (btrfs_header_nritems(&mid->header) > NODEPTRS_PER_BLOCK / 4)
 314                 return 0;
 315
 316         left_buf = read_node_slot(root, parent_buf, pslot - 1);
 317         right_buf = read_node_slot(root, parent_buf, pslot + 1);
 318
 319         /* first, try to make some room in the middle buffer */
 320         if (left_buf) {
 321                 btrfs_cow_block(root, left_buf, parent_buf,
 322                                 pslot - 1, &left_buf);
 323                 left = &left_buf->node;
 324                 orig_slot += btrfs_header_nritems(&left->header);
 325                 wret = push_node_left(root, left_buf, mid_buf);
 326                 if (wret < 0)
 327                         ret = wret;
 328         }
 329
 330         /*
 331          * then try to empty the right most buffer into the middle
 332          */
 333         if (right_buf) {
 334                 btrfs_cow_block(root, right_buf, parent_buf,
 335                                 pslot + 1, &right_buf);
 336                 right = &right_buf->node;
 337                 wret = push_node_left(root, mid_buf, right_buf);
 338                 if (wret < 0)
 339                         ret = wret;
 340                 if (btrfs_header_nritems(&right->header) == 0) {
 341                         u64 blocknr = right_buf->blocknr;
 342                         tree_block_release(root, right_buf);
 343                         clean_tree_block(root, right_buf);
 344                         right_buf = NULL;
 345                         right = NULL;
 346                         wret = del_ptr(root, path, level + 1, pslot + 1);
 347                         if (wret)
 348                                 ret = wret;
 349                         wret = free_extent(root, blocknr, 1);
 350                         if (wret)
 351                                 ret = wret;
 352                 } else {
 353                         memcpy(parent->keys + pslot + 1, right->keys,
 354                                 sizeof(struct btrfs_disk_key));
 355                         BUG_ON(list_empty(&parent_buf->dirty));
 356                 }
 357         }
 358         if (btrfs_header_nritems(&mid->header) == 1) {
 359                 /*
 360                  * we're not allowed to leave a node with one item in the
 361                  * tree during a delete.  A deletion from lower in the tree
 362                  * could try to delete the only pointer in this node.
 363                  * So, pull some keys from the left.
 364                  * There has to be a left pointer at this point because
 365                  * otherwise we would have pulled some pointers from the
 366                  * right
 367                  */
 368                 BUG_ON(!left_buf);
 369                 wret = balance_node_right(root, mid_buf, left_buf);
 370                 if (wret < 0)
 371                         ret = wret;
 372                 BUG_ON(wret == 1);
 373         }
 374         if (btrfs_header_nritems(&mid->header) == 0) {
 375                 /* we've managed to empty the middle node, drop it */
 376                 u64 blocknr = mid_buf->blocknr;
 377                 tree_block_release(root, mid_buf);
 378                 clean_tree_block(root, mid_buf);
 379                 mid_buf = NULL;
 380                 mid = NULL;
 381                 wret = del_ptr(root, path, level + 1, pslot);
 382                 if (wret)
 383                         ret = wret;
 384                 wret = free_extent(root, blocknr, 1);
 385                 if (wret)
 386                         ret = wret;
 387         } else {
 388                 /* update the parent key to reflect our changes */
 389                 memcpy(parent->keys + pslot, mid->keys,
 390                        sizeof(struct btrfs_disk_key));
 391                 BUG_ON(list_empty(&parent_buf->dirty));
 392         }
 393
 394         /* update the path */
 395         if (left_buf) {
 396                 if (btrfs_header_nritems(&left->header) > orig_slot) {
 397                         left_buf->count++; // released below
 398                         path->nodes[level] = left_buf;
 399                         path->slots[level + 1] -= 1;
 400                         path->slots[level] = orig_slot;
 401                         if (mid_buf)
 402                                 tree_block_release(root, mid_buf);
 403                 } else {
 404                         orig_slot -= btrfs_header_nritems(&left->header);
 405                         path->slots[level] = orig_slot;
 406                 }
 407         }
 408         /* double check we haven't messed things up */
 409         check_block(path, level);
 410         if (orig_ptr != path->nodes[level]->node.blockptrs[path->slots[level]])
 411                 BUG();
 412
 413         if (right_buf)
 414                 tree_block_release(root, right_buf);
 415         if (left_buf)
 416                 tree_block_release(root, left_buf);
 417         return ret;
 418 }
 419
 420 /*
 421  * look for key in the tree.  path is filled in with nodes along the way
 422  * if key is found, we return zero and you can find the item in the leaf
 423  * level of the path (level 0)
 424  *
 425  * If the key isn't found, the path points to the slot where it should
 426  * be inserted, and 1 is returned.  If there are other errors during the
 427  * search a negative error number is returned.
 428  *
 429  * if ins_len > 0, nodes and leaves will be split as we walk down the
 430  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
 431  * possible)
 432  */
 433 int search_slot(struct ctree_root *root, struct btrfs_key *key,
 434                 struct ctree_path *p, int ins_len, int cow)
 435 {
 436         struct tree_buffer *b;
 437         struct tree_buffer *cow_buf;
 438         struct node *c;
 439         int slot;
 440         int ret;
 441         int level;
 442
 443 again:
 444         b = root->node;
 445         b->count++;
 446         while (b) {
 447                 level = btrfs_header_level(&b->node.header);
 448                 if (cow) {
 449                         int wret;
 450                         wret = btrfs_cow_block(root, b, p->nodes[level + 1],
 451                                                p->slots[level + 1], &cow_buf);
 452                         b = cow_buf;
 453                 }
 454                 BUG_ON(!cow && ins_len);
 455                 c = &b->node;
 456                 p->nodes[level] = b;
 457                 ret = check_block(p, level);
 458                 if (ret)
 459                         return -1;
 460                 ret = bin_search(c, key, &slot);
 461                 if (!btrfs_is_leaf(c)) {
 462                         if (ret && slot > 0)
 463                                 slot -= 1;
 464                         p->slots[level] = slot;
 465                         if (ins_len > 0 && btrfs_header_nritems(&c->header) ==
 466                             NODEPTRS_PER_BLOCK) {
 467                                 int sret = split_node(root, p, level);
 468                                 BUG_ON(sret > 0);
 469                                 if (sret)
 470                                         return sret;
 471                                 b = p->nodes[level];
 472                                 c = &b->node;
 473                                 slot = p->slots[level];
 474                         } else if (ins_len < 0) {
 475                                 int sret = balance_level(root, p, level);
 476                                 if (sret)
 477                                         return sret;
 478                                 b = p->nodes[level];
 479                                 if (!b)
 480                                         goto again;
 481                                 c = &b->node;
 482                                 slot = p->slots[level];
 483                                 BUG_ON(btrfs_header_nritems(&c->header) == 1);
 484                         }
 485                         b = read_tree_block(root, c->blockptrs[slot]);
 486                 } else {
 487                         struct leaf *l = (struct leaf *)c;
 488                         p->slots[level] = slot;
 489                         if (ins_len > 0 && leaf_free_space(l) <
 490                             sizeof(struct btrfs_item) + ins_len) {
 491                                 int sret = split_leaf(root, p, ins_len);
 492                                 BUG_ON(sret > 0);
 493                                 if (sret)
 494                                         return sret;
 495                         }
 496                         BUG_ON(root->node->count == 1);
 497                         return ret;
 498                 }
 499         }
 500         BUG_ON(root->node->count == 1);
 501         return 1;
 502 }
 503
 504 /*
 505  * adjust the pointers going up the tree, starting at level
 506  * making sure the right key of each node is points to 'key'.
 507  * This is used after shifting pointers to the left, so it stops
 508  * fixing up pointers when a given leaf/node is not in slot 0 of the
 509  * higher levels
 510  *
 511  * If this fails to write a tree block, it returns -1, but continues
 512  * fixing up the blocks in ram so the tree is consistent.
 513  */
 514 static int fixup_low_keys(struct ctree_root *root,
 515                            struct ctree_path *path, struct btrfs_disk_key *key,
 516                            int level)
 517 {
 518         int i;
 519         int ret = 0;
 520         for (i = level; i < MAX_LEVEL; i++) {
 521                 struct node *t;
 522                 int tslot = path->slots[i];
 523                 if (!path->nodes[i])
 524                         break;
 525                 t = &path->nodes[i]->node;
 526                 memcpy(t->keys + tslot, key, sizeof(*key));
 527                 BUG_ON(list_empty(&path->nodes[i]->dirty));
 528                 if (tslot != 0)
 529                         break;
 530         }
 531         return ret;
 532 }
 533
 534 /*
 535  * try to push data from one node into the next node left in the
 536  * tree.
 537  *
 538  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
 539  * error, and > 0 if there was no room in the left hand block.
 540  */
 541 static int push_node_left(struct ctree_root *root, struct tree_buffer *dst_buf,
 542                           struct tree_buffer *src_buf)
 543 {
 544         struct node *src = &src_buf->node;
 545         struct node *dst = &dst_buf->node;
 546         int push_items = 0;
 547         int src_nritems;
 548         int dst_nritems;
 549         int ret = 0;
 550
 551         src_nritems = btrfs_header_nritems(&src->header);
 552         dst_nritems = btrfs_header_nritems(&dst->header);
 553         push_items = NODEPTRS_PER_BLOCK - dst_nritems;
 554         if (push_items <= 0) {
 555                 return 1;
 556         }
 557
 558         if (src_nritems < push_items)
 559                 push_items = src_nritems;
 560
 561         memcpy(dst->keys + dst_nritems, src->keys,
 562                 push_items * sizeof(struct btrfs_disk_key));
 563         memcpy(dst->blockptrs + dst_nritems, src->blockptrs,
 564                 push_items * sizeof(u64));
 565         if (push_items < src_nritems) {
 566                 memmove(src->keys, src->keys + push_items,
 567                         (src_nritems - push_items) *
 568                         sizeof(struct btrfs_disk_key));
 569                 memmove(src->blockptrs, src->blockptrs + push_items,
 570                         (src_nritems - push_items) * sizeof(u64));
 571         }
 572         btrfs_set_header_nritems(&src->header, src_nritems - push_items);
 573         btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
 574         BUG_ON(list_empty(&src_buf->dirty));
 575         BUG_ON(list_empty(&dst_buf->dirty));
 576         return ret;
 577 }
 578
 579 /*
 580  * try to push data from one node into the next node right in the
 581  * tree.
 582  *
 583  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
 584  * error, and > 0 if there was no room in the right hand block.
 585  *
 586  * this will  only push up to 1/2 the contents of the left node over
 587  */
 588 static int balance_node_right(struct ctree_root *root,
 589                               struct tree_buffer *dst_buf,
 590                               struct tree_buffer *src_buf)
 591 {
 592         struct node *src = &src_buf->node;
 593         struct node *dst = &dst_buf->node;
 594         int push_items = 0;
 595         int max_push;
 596         int src_nritems;
 597         int dst_nritems;
 598         int ret = 0;
 599
 600         src_nritems = btrfs_header_nritems(&src->header);
 601         dst_nritems = btrfs_header_nritems(&dst->header);
 602         push_items = NODEPTRS_PER_BLOCK - dst_nritems;
 603         if (push_items <= 0) {
 604                 return 1;
 605         }
 606
 607         max_push = src_nritems / 2 + 1;
 608         /* don't try to empty the node */
 609         if (max_push > src_nritems)
 610                 return 1;
 611         if (max_push < push_items)
 612                 push_items = max_push;
 613
 614         memmove(dst->keys + push_items, dst->keys,
 615                 dst_nritems * sizeof(struct btrfs_disk_key));
 616         memmove(dst->blockptrs + push_items, dst->blockptrs,
 617                 dst_nritems * sizeof(u64));
 618         memcpy(dst->keys, src->keys + src_nritems - push_items,
 619                 push_items * sizeof(struct btrfs_disk_key));
 620         memcpy(dst->blockptrs, src->blockptrs + src_nritems - push_items,
 621                 push_items * sizeof(u64));
 622
 623         btrfs_set_header_nritems(&src->header, src_nritems - push_items);
 624         btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
 625
 626         BUG_ON(list_empty(&src_buf->dirty));
 627         BUG_ON(list_empty(&dst_buf->dirty));
 628         return ret;
 629 }
 630
 631 /*
 632  * helper function to insert a new root level in the tree.
 633  * A new node is allocated, and a single item is inserted to
 634  * point to the existing root
 635  *
 636  * returns zero on success or < 0 on failure.
 637  */
 638 static int insert_new_root(struct ctree_root *root,
 639                            struct ctree_path *path, int level)
 640 {
 641         struct tree_buffer *t;
 642         struct node *lower;
 643         struct node *c;
 644         struct btrfs_disk_key *lower_key;
 645
 646         BUG_ON(path->nodes[level]);
 647         BUG_ON(path->nodes[level-1] != root->node);
 648
 649         t = alloc_free_block(root);
 650         c = &t->node;
 651         memset(c, 0, sizeof(c));
 652         btrfs_set_header_nritems(&c->header, 1);
 653         btrfs_set_header_level(&c->header, level);
 654         btrfs_set_header_blocknr(&c->header, t->blocknr);
 655         btrfs_set_header_parentid(&c->header,
 656                                btrfs_header_parentid(&root->node->node.header));
 657         lower = &path->nodes[level-1]->node;
 658         if (btrfs_is_leaf(lower))
 659                 lower_key = &((struct leaf *)lower)->items[0].key;
 660         else
 661                 lower_key = lower->keys;
 662         memcpy(c->keys, lower_key, sizeof(struct btrfs_disk_key));
 663         c->blockptrs[0] = path->nodes[level-1]->blocknr;
 664         /* the super has an extra ref to root->node */
 665         tree_block_release(root, root->node);
 666         root->node = t;
 667         t->count++;
 668         path->nodes[level] = t;
 669         path->slots[level] = 0;
 670         return 0;
 671 }
 672
 673 /*
 674  * worker function to insert a single pointer in a node.
 675  * the node should have enough room for the pointer already
 676  *
 677  * slot and level indicate where you want the key to go, and
 678  * blocknr is the block the key points to.
 679  *
 680  * returns zero on success and < 0 on any error
 681  */
 682 static int insert_ptr(struct ctree_root *root,
 683                 struct ctree_path *path, struct btrfs_disk_key *key,
 684                 u64 blocknr, int slot, int level)
 685 {
 686         struct node *lower;
 687         int nritems;
 688
 689         BUG_ON(!path->nodes[level]);
 690         lower = &path->nodes[level]->node;
 691         nritems = btrfs_header_nritems(&lower->header);
 692         if (slot > nritems)
 693                 BUG();
 694         if (nritems == NODEPTRS_PER_BLOCK)
 695                 BUG();
 696         if (slot != nritems) {
 697                 memmove(lower->keys + slot + 1, lower->keys + slot,
 698                         (nritems - slot) * sizeof(struct btrfs_disk_key));
 699                 memmove(lower->blockptrs + slot + 1, lower->blockptrs + slot,
 700                         (nritems - slot) * sizeof(u64));
 701         }
 702         memcpy(lower->keys + slot, key, sizeof(struct btrfs_disk_key));
 703         lower->blockptrs[slot] = blocknr;
 704         btrfs_set_header_nritems(&lower->header, nritems + 1);
 705         if (lower->keys[1].objectid == 0)
 706                         BUG();
 707         BUG_ON(list_empty(&path->nodes[level]->dirty));
 708         return 0;
 709 }
 710
 711 /*
 712  * split the node at the specified level in path in two.
 713  * The path is corrected to point to the appropriate node after the split
 714  *
 715  * Before splitting this tries to make some room in the node by pushing
 716  * left and right, if either one works, it returns right away.
 717  *
 718  * returns 0 on success and < 0 on failure
 719  */
 720 static int split_node(struct ctree_root *root, struct ctree_path *path,
 721                       int level)
 722 {
 723         struct tree_buffer *t;
 724         struct node *c;
 725         struct tree_buffer *split_buffer;
 726         struct node *split;
 727         int mid;
 728         int ret;
 729         int wret;
 730         u32 c_nritems;
 731
 732         t = path->nodes[level];
 733         c = &t->node;
 734         if (t == root->node) {
 735                 /* trying to split the root, lets make a new one */
 736                 ret = insert_new_root(root, path, level + 1);
 737                 if (ret)
 738                         return ret;
 739         }
 740         c_nritems = btrfs_header_nritems(&c->header);
 741         split_buffer = alloc_free_block(root);
 742         split = &split_buffer->node;
 743         btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
 744         btrfs_set_header_blocknr(&split->header, split_buffer->blocknr);
 745         btrfs_set_header_parentid(&split->header,
 746                                btrfs_header_parentid(&root->node->node.header));
 747         mid = (c_nritems + 1) / 2;
 748         memcpy(split->keys, c->keys + mid,
 749                 (c_nritems - mid) * sizeof(struct btrfs_disk_key));
 750         memcpy(split->blockptrs, c->blockptrs + mid,
 751                 (c_nritems - mid) * sizeof(u64));
 752         btrfs_set_header_nritems(&split->header, c_nritems - mid);
 753         btrfs_set_header_nritems(&c->header, mid);
 754         ret = 0;
 755
 756         BUG_ON(list_empty(&t->dirty));
 757         wret = insert_ptr(root, path, split->keys, split_buffer->blocknr,
 758                           path->slots[level + 1] + 1, level + 1);
 759         if (wret)
 760                 ret = wret;
 761
 762         if (path->slots[level] >= mid) {
 763                 path->slots[level] -= mid;
 764                 tree_block_release(root, t);
 765                 path->nodes[level] = split_buffer;
 766                 path->slots[level + 1] += 1;
 767         } else {
 768                 tree_block_release(root, split_buffer);
 769         }
 770         return ret;
 771 }
 772
 773 /*
 774  * how many bytes are required to store the items in a leaf.  start
 775  * and nr indicate which items in the leaf to check.  This totals up the
 776  * space used both by the item structs and the item data
 777  */
 778 static int leaf_space_used(struct leaf *l, int start, int nr)
 779 {
 780         int data_len;
 781         int end = start + nr - 1;
 782
 783         if (!nr)
 784                 return 0;
 785         data_len = btrfs_item_end(l->items + start);
 786         data_len = data_len - btrfs_item_offset(l->items + end);
 787         data_len += sizeof(struct btrfs_item) * nr;
 788         return data_len;
 789 }
 790
 791 /*
 792  * push some data in the path leaf to the right, trying to free up at
 793  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
 794  *
 795  * returns 1 if the push failed because the other node didn't have enough
 796  * room, 0 if everything worked out and < 0 if there were major errors.
 797  */
 798 static int push_leaf_right(struct ctree_root *root, struct ctree_path *path,
 799                            int data_size)
 800 {
 801         struct tree_buffer *left_buf = path->nodes[0];
 802         struct leaf *left = &left_buf->leaf;
 803         struct leaf *right;
 804         struct tree_buffer *right_buf;
 805         struct tree_buffer *upper;
 806         int slot;
 807         int i;
 808         int free_space;
 809         int push_space = 0;
 810         int push_items = 0;
 811         struct btrfs_item *item;
 812         u32 left_nritems;
 813         u32 right_nritems;
 814
 815         slot = path->slots[1];
 816         if (!path->nodes[1]) {
 817                 return 1;
 818         }
 819         upper = path->nodes[1];
 820         if (slot >= btrfs_header_nritems(&upper->node.header) - 1) {
 821                 return 1;
 822         }
 823         right_buf = read_tree_block(root, upper->node.blockptrs[slot + 1]);
 824         right = &right_buf->leaf;
 825         free_space = leaf_free_space(right);
 826         if (free_space < data_size + sizeof(struct btrfs_item)) {
 827                 tree_block_release(root, right_buf);
 828                 return 1;
 829         }
 830         /* cow and double check */
 831         btrfs_cow_block(root, right_buf, upper, slot + 1, &right_buf);
 832         right = &right_buf->leaf;
 833         free_space = leaf_free_space(right);
 834         if (free_space < data_size + sizeof(struct btrfs_item)) {
 835                 tree_block_release(root, right_buf);
 836                 return 1;
 837         }
 838
 839         left_nritems = btrfs_header_nritems(&left->header);
 840         for (i = left_nritems - 1; i >= 0; i--) {
 841                 item = left->items + i;
 842                 if (path->slots[0] == i)
 843                         push_space += data_size + sizeof(*item);
 844                 if (btrfs_item_size(item) + sizeof(*item) + push_space >
 845                     free_space)
 846                         break;
 847                 push_items++;
 848                 push_space += btrfs_item_size(item) + sizeof(*item);
 849         }
 850         if (push_items == 0) {
 851                 tree_block_release(root, right_buf);
 852                 return 1;
 853         }
 854         right_nritems = btrfs_header_nritems(&right->header);
 855         /* push left to right */
 856         push_space = btrfs_item_end(left->items + left_nritems - push_items);
 857         push_space -= leaf_data_end(left);
 858         /* make room in the right data area */
 859         memmove(right->data + leaf_data_end(right) - push_space,
 860                 right->data + leaf_data_end(right),
 861                 LEAF_DATA_SIZE - leaf_data_end(right));
 862         /* copy from the left data area */
 863         memcpy(right->data + LEAF_DATA_SIZE - push_space,
 864                 left->data + leaf_data_end(left),
 865                 push_space);
 866         memmove(right->items + push_items, right->items,
 867                 right_nritems * sizeof(struct btrfs_item));
 868         /* copy the items from left to right */
 869         memcpy(right->items, left->items + left_nritems - push_items,
 870                 push_items * sizeof(struct btrfs_item));
 871
 872         /* update the item pointers */
 873         right_nritems += push_items;
 874         btrfs_set_header_nritems(&right->header, right_nritems);
 875         push_space = LEAF_DATA_SIZE;
 876         for (i = 0; i < right_nritems; i++) {
 877                 btrfs_set_item_offset(right->items + i, push_space -
 878                                       btrfs_item_size(right->items + i));
 879                 push_space = btrfs_item_offset(right->items + i);
 880         }
 881         left_nritems -= push_items;
 882         btrfs_set_header_nritems(&left->header, left_nritems);
 883
 884         BUG_ON(list_empty(&left_buf->dirty));
 885         BUG_ON(list_empty(&right_buf->dirty));
 886         memcpy(upper->node.keys + slot + 1,
 887                 &right->items[0].key, sizeof(struct btrfs_disk_key));
 888         BUG_ON(list_empty(&upper->dirty));
 889
 890         /* then fixup the leaf pointer in the path */
 891         if (path->slots[0] >= left_nritems) {
 892                 path->slots[0] -= left_nritems;
 893                 tree_block_release(root, path->nodes[0]);
 894                 path->nodes[0] = right_buf;
 895                 path->slots[1] += 1;
 896         } else {
 897                 tree_block_release(root, right_buf);
 898         }
 899         return 0;
 900 }
 901 /*
 902  * push some data in the path leaf to the left, trying to free up at
 903  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
 904  */
 905 static int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
 906                           int data_size)
 907 {
 908         struct tree_buffer *right_buf = path->nodes[0];
 909         struct leaf *right = &right_buf->leaf;
 910         struct tree_buffer *t;
 911         struct leaf *left;
 912         int slot;
 913         int i;
 914         int free_space;
 915         int push_space = 0;
 916         int push_items = 0;
 917         struct btrfs_item *item;
 918         u32 old_left_nritems;
 919         int ret = 0;
 920         int wret;
 921
 922         slot = path->slots[1];
 923         if (slot == 0) {
 924                 return 1;
 925         }
 926         if (!path->nodes[1]) {
 927                 return 1;
 928         }
 929         t = read_tree_block(root, path->nodes[1]->node.blockptrs[slot - 1]);
 930         left = &t->leaf;
 931         free_space = leaf_free_space(left);
 932         if (free_space < data_size + sizeof(struct btrfs_item)) {
 933                 tree_block_release(root, t);
 934                 return 1;
 935         }
 936
 937         /* cow and double check */
 938         btrfs_cow_block(root, t, path->nodes[1], slot - 1, &t);
 939         left = &t->leaf;
 940         free_space = leaf_free_space(left);
 941         if (free_space < data_size + sizeof(struct btrfs_item)) {
 942                 tree_block_release(root, t);
 943                 return 1;
 944         }
 945
 946         for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
 947                 item = right->items + i;
 948                 if (path->slots[0] == i)
 949                         push_space += data_size + sizeof(*item);
 950                 if (btrfs_item_size(item) + sizeof(*item) + push_space >
 951                     free_space)
 952                         break;
 953                 push_items++;
 954                 push_space += btrfs_item_size(item) + sizeof(*item);
 955         }
 956         if (push_items == 0) {
 957                 tree_block_release(root, t);
 958                 return 1;
 959         }
 960         /* push data from right to left */
 961         memcpy(left->items + btrfs_header_nritems(&left->header),
 962                 right->items, push_items * sizeof(struct btrfs_item));
 963         push_space = LEAF_DATA_SIZE -
 964                      btrfs_item_offset(right->items + push_items -1);
 965         memcpy(left->data + leaf_data_end(left) - push_space,
 966                 right->data + btrfs_item_offset(right->items + push_items - 1),
 967                 push_space);
 968         old_left_nritems = btrfs_header_nritems(&left->header);
 969         BUG_ON(old_left_nritems < 0);
 970
 971         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
 972                 u16 ioff = btrfs_item_offset(left->items + i);
 973                 btrfs_set_item_offset(left->items + i, ioff - (LEAF_DATA_SIZE -
 974                                       btrfs_item_offset(left->items +
 975                                                         old_left_nritems - 1)));
 976         }
 977         btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
 978
 979         /* fixup right node */
 980         push_space = btrfs_item_offset(right->items + push_items - 1) -
 981                      leaf_data_end(right);
 982         memmove(right->data + LEAF_DATA_SIZE - push_space, right->data +
 983                 leaf_data_end(right), push_space);
 984         memmove(right->items, right->items + push_items,
 985                 (btrfs_header_nritems(&right->header) - push_items) *
 986                 sizeof(struct btrfs_item));
 987         btrfs_set_header_nritems(&right->header,
 988                                  btrfs_header_nritems(&right->header) -
 989                                  push_items);
 990         push_space = LEAF_DATA_SIZE;
 991
 992         for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
 993                 btrfs_set_item_offset(right->items + i, push_space -
 994                                       btrfs_item_size(right->items + i));
 995                 push_space = btrfs_item_offset(right->items + i);
 996         }
 997
 998         BUG_ON(list_empty(&t->dirty));
 999         BUG_ON(list_empty(&right_buf->dirty));
1000
1001         wret = fixup_low_keys(root, path, &right->items[0].key, 1);
1002         if (wret)
1003                 ret = wret;
1004
1005         /* then fixup the leaf pointer in the path */
1006         if (path->slots[0] < push_items) {
1007                 path->slots[0] += old_left_nritems;
1008                 tree_block_release(root, path->nodes[0]);
1009                 path->nodes[0] = t;
1010                 path->slots[1] -= 1;
1011         } else {
1012                 tree_block_release(root, t);
1013                 path->slots[0] -= push_items;
1014         }
1015         BUG_ON(path->slots[0] < 0);
1016         return ret;
1017 }
1018
1019 /*
1020  * split the path's leaf in two, making sure there is at least data_size
1021  * available for the resulting leaf level of the path.
1022  *
1023  * returns 0 if all went well and < 0 on failure.
1024  */
1025 static int split_leaf(struct ctree_root *root, struct ctree_path *path,
1026                       int data_size)
1027 {
1028         struct tree_buffer *l_buf;
1029         struct leaf *l;
1030         u32 nritems;
1031         int mid;
1032         int slot;
1033         struct leaf *right;
1034         struct tree_buffer *right_buffer;
1035         int space_needed = data_size + sizeof(struct btrfs_item);
1036         int data_copy_size;
1037         int rt_data_off;
1038         int i;
1039         int ret;
1040         int wret;
1041
1042         l_buf = path->nodes[0];
1043         l = &l_buf->leaf;
1044
1045         /* did the pushes work? */
1046         if (leaf_free_space(l) >= sizeof(struct btrfs_item) + data_size)
1047                 return 0;
1048
1049         if (!path->nodes[1]) {
1050                 ret = insert_new_root(root, path, 1);
1051                 if (ret)
1052                         return ret;
1053         }
1054         slot = path->slots[0];
1055         nritems = btrfs_header_nritems(&l->header);
1056         mid = (nritems + 1)/ 2;
1057         right_buffer = alloc_free_block(root);
1058         BUG_ON(!right_buffer);
1059         BUG_ON(mid == nritems);
1060         right = &right_buffer->leaf;
1061         memset(right, 0, sizeof(*right));
1062         if (mid <= slot) {
1063                 /* FIXME, just alloc a new leaf here */
1064                 if (leaf_space_used(l, mid, nritems - mid) + space_needed >
1065                         LEAF_DATA_SIZE)
1066                         BUG();
1067         } else {
1068                 /* FIXME, just alloc a new leaf here */
1069                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1070                         LEAF_DATA_SIZE)
1071                         BUG();
1072         }
1073         btrfs_set_header_nritems(&right->header, nritems - mid);
1074         btrfs_set_header_blocknr(&right->header, right_buffer->blocknr);
1075         btrfs_set_header_level(&right->header, 0);
1076         btrfs_set_header_parentid(&right->header,
1077                                btrfs_header_parentid(&root->node->node.header));
1078         data_copy_size = btrfs_item_end(l->items + mid) - leaf_data_end(l);
1079         memcpy(right->items, l->items + mid,
1080                (nritems - mid) * sizeof(struct btrfs_item));
1081         memcpy(right->data + LEAF_DATA_SIZE - data_copy_size,
1082                l->data + leaf_data_end(l), data_copy_size);
1083         rt_data_off = LEAF_DATA_SIZE - btrfs_item_end(l->items + mid);
1084
1085         for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1086                 u16 ioff = btrfs_item_offset(right->items + i);
1087                 btrfs_set_item_offset(right->items + i, ioff + rt_data_off);
1088         }
1089
1090         btrfs_set_header_nritems(&l->header, mid);
1091         ret = 0;
1092         wret = insert_ptr(root, path, &right->items[0].key,
1093                           right_buffer->blocknr, path->slots[1] + 1, 1);
1094         if (wret)
1095                 ret = wret;
1096         BUG_ON(list_empty(&right_buffer->dirty));
1097         BUG_ON(list_empty(&l_buf->dirty));
1098         BUG_ON(path->slots[0] != slot);
1099         if (mid <= slot) {
1100                 tree_block_release(root, path->nodes[0]);
1101                 path->nodes[0] = right_buffer;
1102                 path->slots[0] -= mid;
1103                 path->slots[1] += 1;
1104         } else
1105                 tree_block_release(root, right_buffer);
1106         BUG_ON(path->slots[0] < 0);
1107         return ret;
1108 }
1109
1110 /*
1111  * Given a key and some data, insert an item into the tree.
1112  * This does all the path init required, making room in the tree if needed.
1113  */
1114 int insert_item(struct ctree_root *root, struct btrfs_key *cpu_key,
1115                           void *data, int data_size)
1116 {
1117         int ret = 0;
1118         int slot;
1119         int slot_orig;
1120         struct leaf *leaf;
1121         struct tree_buffer *leaf_buf;
1122         u32 nritems;
1123         unsigned int data_end;
1124         struct ctree_path path;
1125         struct btrfs_disk_key disk_key;
1126
1127         btrfs_cpu_key_to_disk(&disk_key, cpu_key);
1128
1129         /* create a root if there isn't one */
1130         if (!root->node)
1131                 BUG();
1132         init_path(&path);
1133         ret = search_slot(root, cpu_key, &path, data_size, 1);
1134         if (ret == 0) {
1135                 release_path(root, &path);
1136                 return -EEXIST;
1137         }
1138         if (ret < 0)
1139                 goto out;
1140
1141         slot_orig = path.slots[0];
1142         leaf_buf = path.nodes[0];
1143         leaf = &leaf_buf->leaf;
1144
1145         nritems = btrfs_header_nritems(&leaf->header);
1146         data_end = leaf_data_end(leaf);
1147
1148         if (leaf_free_space(leaf) <  sizeof(struct btrfs_item) + data_size)
1149                 BUG();
1150
1151         slot = path.slots[0];
1152         BUG_ON(slot < 0);
1153         if (slot != nritems) {
1154                 int i;
1155                 unsigned int old_data = btrfs_item_end(leaf->items + slot);
1156
1157                 /*
1158                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
1159                  */
1160                 /* first correct the data pointers */
1161                 for (i = slot; i < nritems; i++) {
1162                         u16 ioff = btrfs_item_offset(leaf->items + i);
1163                         btrfs_set_item_offset(leaf->items + i,
1164                                               ioff - data_size);
1165                 }
1166
1167                 /* shift the items */
1168                 memmove(leaf->items + slot + 1, leaf->items + slot,
1169                         (nritems - slot) * sizeof(struct btrfs_item));
1170
1171                 /* shift the data */
1172                 memmove(leaf->data + data_end - data_size, leaf->data +
1173                         data_end, old_data - data_end);
1174                 data_end = old_data;
1175         }
1176         /* copy the new data in */
1177         memcpy(&leaf->items[slot].key, &disk_key,
1178                 sizeof(struct btrfs_disk_key));
1179         btrfs_set_item_offset(leaf->items + slot, data_end - data_size);
1180         btrfs_set_item_size(leaf->items + slot, data_size);
1181         memcpy(leaf->data + data_end - data_size, data, data_size);
1182         btrfs_set_header_nritems(&leaf->header, nritems + 1);
1183
1184         ret = 0;
1185         if (slot == 0)
1186                 ret = fixup_low_keys(root, &path, &disk_key, 1);
1187
1188         BUG_ON(list_empty(&leaf_buf->dirty));
1189         if (leaf_free_space(leaf) < 0)
1190                 BUG();
1191         check_leaf(&path, 0);
1192 out:
1193         release_path(root, &path);
1194         return ret;
1195 }
1196
1197 /*
1198  * delete the pointer from a given node.
1199  *
1200  * If the delete empties a node, the node is removed from the tree,
1201  * continuing all the way the root if required.  The root is converted into
1202  * a leaf if all the nodes are emptied.
1203  */
1204 static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
1205                    int slot)
1206 {
1207         struct node *node;
1208         struct tree_buffer *parent = path->nodes[level];
1209         u32 nritems;
1210         int ret = 0;
1211         int wret;
1212
1213         node = &parent->node;
1214         nritems = btrfs_header_nritems(&node->header);
1215         if (slot != nritems -1) {
1216                 memmove(node->keys + slot, node->keys + slot + 1,
1217                         sizeof(struct btrfs_disk_key) * (nritems - slot - 1));
1218                 memmove(node->blockptrs + slot,
1219                         node->blockptrs + slot + 1,
1220                         sizeof(u64) * (nritems - slot - 1));
1221         }
1222         nritems--;
1223         btrfs_set_header_nritems(&node->header, nritems);
1224         if (nritems == 0 && parent == root->node) {
1225                 BUG_ON(btrfs_header_level(&root->node->node.header) != 1);
1226                 /* just turn the root into a leaf and break */
1227                 btrfs_set_header_level(&root->node->node.header, 0);
1228         } else if (slot == 0) {
1229                 wret = fixup_low_keys(root, path, node->keys, level + 1);
1230                 if (wret)
1231                         ret = wret;
1232         }
1233         BUG_ON(list_empty(&parent->dirty));
1234         return ret;
1235 }
1236
1237 /*
1238  * delete the item at the leaf level in path.  If that empties
1239  * the leaf, remove it from the tree
1240  */
1241 int del_item(struct ctree_root *root, struct ctree_path *path)
1242 {
1243         int slot;
1244         struct leaf *leaf;
1245         struct tree_buffer *leaf_buf;
1246         int doff;
1247         int dsize;
1248         int ret = 0;
1249         int wret;
1250         u32 nritems;
1251
1252         leaf_buf = path->nodes[0];
1253         leaf = &leaf_buf->leaf;
1254         slot = path->slots[0];
1255         doff = btrfs_item_offset(leaf->items + slot);
1256         dsize = btrfs_item_size(leaf->items + slot);
1257         nritems = btrfs_header_nritems(&leaf->header);
1258
1259         if (slot != nritems - 1) {
1260                 int i;
1261                 int data_end = leaf_data_end(leaf);
1262                 memmove(leaf->data + data_end + dsize,
1263                         leaf->data + data_end,
1264                         doff - data_end);
1265                 for (i = slot + 1; i < nritems; i++) {
1266                         u16 ioff = btrfs_item_offset(leaf->items + i);
1267                         btrfs_set_item_offset(leaf->items + i, ioff + dsize);
1268                 }
1269                 memmove(leaf->items + slot, leaf->items + slot + 1,
1270                         sizeof(struct btrfs_item) *
1271                         (nritems - slot - 1));
1272         }
1273         btrfs_set_header_nritems(&leaf->header, nritems - 1);
1274         nritems--;
1275         /* delete the leaf if we've emptied it */
1276         if (nritems == 0) {
1277                 if (leaf_buf == root->node) {
1278                         btrfs_set_header_level(&leaf->header, 0);
1279                         BUG_ON(list_empty(&leaf_buf->dirty));
1280                 } else {
1281                         clean_tree_block(root, leaf_buf);
1282                         wret = del_ptr(root, path, 1, path->slots[1]);
1283                         if (wret)
1284                                 ret = wret;
1285                         wret = free_extent(root, leaf_buf->blocknr, 1);
1286                         if (wret)
1287                                 ret = wret;
1288                 }
1289         } else {
1290                 int used = leaf_space_used(leaf, 0, nritems);
1291                 if (slot == 0) {
1292                         wret = fixup_low_keys(root, path,
1293                                                    &leaf->items[0].key, 1);
1294                         if (wret)
1295                                 ret = wret;
1296                 }
1297                 BUG_ON(list_empty(&leaf_buf->dirty));
1298
1299                 /* delete the leaf if it is mostly empty */
1300                 if (used < LEAF_DATA_SIZE / 3) {
1301                         /* push_leaf_left fixes the path.
1302                          * make sure the path still points to our leaf
1303                          * for possible call to del_ptr below
1304                          */
1305                         slot = path->slots[1];
1306                         leaf_buf->count++;
1307                         wret = push_leaf_left(root, path, 1);
1308                         if (wret < 0)
1309                                 ret = wret;
1310                         if (path->nodes[0] == leaf_buf &&
1311                             btrfs_header_nritems(&leaf->header)) {
1312                                 wret = push_leaf_right(root, path, 1);
1313                                 if (wret < 0)
1314                                         ret = wret;
1315                         }
1316                         if (btrfs_header_nritems(&leaf->header) == 0) {
1317                                 u64 blocknr = leaf_buf->blocknr;
1318                                 clean_tree_block(root, leaf_buf);
1319                                 wret = del_ptr(root, path, 1, slot);
1320                                 if (wret)
1321                                         ret = wret;
1322                                 tree_block_release(root, leaf_buf);
1323                                 wret = free_extent(root, blocknr, 1);
1324                                 if (wret)
1325                                         ret = wret;
1326                         } else {
1327                                 tree_block_release(root, leaf_buf);
1328                         }
1329                 }
1330         }
1331         return ret;
1332 }
1333
1334 /*
1335  * walk up the tree as far as required to find the next leaf.
1336  * returns 0 if it found something or 1 if there are no greater leaves.
1337  * returns < 0 on io errors.
1338  */
1339 int next_leaf(struct ctree_root *root, struct ctree_path *path)
1340 {
1341         int slot;
1342         int level = 1;
1343         u64 blocknr;
1344         struct tree_buffer *c;
1345         struct tree_buffer *next = NULL;
1346
1347         while(level < MAX_LEVEL) {
1348                 if (!path->nodes[level])
1349                         return 1;
1350                 slot = path->slots[level] + 1;
1351                 c = path->nodes[level];
1352                 if (slot >= btrfs_header_nritems(&c->node.header)) {
1353                         level++;
1354                         continue;
1355                 }
1356                 blocknr = c->node.blockptrs[slot];
1357                 if (next)
1358                         tree_block_release(root, next);
1359                 next = read_tree_block(root, blocknr);
1360                 break;
1361         }
1362         path->slots[level] = slot;
1363         while(1) {
1364                 level--;
1365                 c = path->nodes[level];
1366                 tree_block_release(root, c);
1367                 path->nodes[level] = next;
1368                 path->slots[level] = 0;
1369                 if (!level)
1370                         break;
1371                 next = read_tree_block(root, next->node.blockptrs[0]);
1372         }
1373         return 0;
1374 }
1375
1376