ctree.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include "kerncompat.h"
  22 #include "ctree.h"
  23 #include "disk-io.h"
  24 #include "transaction.h"
  25 #include "print-tree.h"
  26
  27 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  28                       *root, struct btrfs_path *path, int level);
  29 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  30                       *root, struct btrfs_key *ins_key,
  31                       struct btrfs_path *path, int data_size, int extend);
  32 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
  33                           *root, struct btrfs_buffer *dst, struct btrfs_buffer
  34                           *src);
  35 static int balance_node_right(struct btrfs_trans_handle *trans, struct
  36                               btrfs_root *root, struct btrfs_buffer *dst_buf,
  37                               struct btrfs_buffer *src_buf);
  38 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  39                    struct btrfs_path *path, int level, int slot);
  40
  41 inline void btrfs_init_path(struct btrfs_path *p)
  42 {
  43         memset(p, 0, sizeof(*p));
  44 }
  45
  46 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
  47 {
  48         int i;
  49         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  50                 if (!p->nodes[i])
  51                         break;
  52                 btrfs_block_release(root, p->nodes[i]);
  53         }
  54         memset(p, 0, sizeof(*p));
  55 }
  56 int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
  57                            *root, struct btrfs_buffer *buf, struct btrfs_buffer
  58                            *parent, int parent_slot, struct btrfs_buffer
  59                            **cow_ret)
  60 {
  61         struct btrfs_buffer *cow;
  62         u64 root_gen;
  63
  64         if (!list_empty(&buf->dirty)) {
  65                 *cow_ret = buf;
  66                 return 0;
  67         }
  68         cow = btrfs_alloc_free_block(trans, root, buf->size);
  69         memcpy(&cow->node, &buf->node, buf->size);
  70         btrfs_set_header_bytenr(&cow->node.header, cow->bytenr);
  71         btrfs_set_header_generation(&cow->node.header, trans->transid);
  72         btrfs_set_header_owner(&cow->node.header, root->root_key.objectid);
  73         *cow_ret = cow;
  74         btrfs_inc_ref(trans, root, buf);
  75         if (buf == root->node) {
  76                 root_gen = btrfs_header_generation(&buf->node.header);
  77                 root->node = cow;
  78                 cow->count++;
  79                 if (buf != root->commit_root)
  80                         btrfs_free_extent(trans, root, buf->bytenr,
  81                                           buf->size, root->root_key.objectid,
  82                                           root_gen, 0, 0, 1);
  83                 btrfs_block_release(root, buf);
  84         } else {
  85                 root_gen = btrfs_header_generation(&parent->node.header);
  86                 btrfs_set_node_blockptr(&parent->node, parent_slot,
  87                                         cow->bytenr);
  88                 btrfs_set_node_ptr_generation(&parent->node, parent_slot,
  89                                               trans->transid);
  90                 BUG_ON(list_empty(&parent->dirty));
  91                 btrfs_free_extent(trans, root, buf->bytenr, buf->size,
  92                                   root->root_key.objectid, root_gen, 0, 0, 1);
  93         }
  94         btrfs_block_release(root, buf);
  95         return 0;
  96 }
  97
  98 /*
  99  * The leaf data grows from end-to-front in the node.
 100  * this returns the address of the start of the last item,
 101  * which is the stop of the leaf data stack
 102  */
 103 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 104                                          struct btrfs_leaf *leaf)
 105 {
 106         u32 nr = btrfs_header_nritems(&leaf->header);
 107         if (nr == 0)
 108                 return BTRFS_LEAF_DATA_SIZE(root);
 109         return btrfs_item_offset(leaf->items + nr - 1);
 110 }
 111
 112 /*
 113  * how many bytes are required to store the items in a leaf.  start
 114  * and nr indicate which items in the leaf to check.  This totals up the
 115  * space used both by the item structs and the item data
 116  */
 117 static int leaf_space_used(struct btrfs_leaf *l, int start, int nr)
 118 {
 119         int data_len;
 120         int nritems = btrfs_header_nritems(&l->header);
 121         int end;
 122
 123         if (nritems < start + nr)
 124                 end = nritems - 1;
 125         else
 126                 end = start + nr - 1;
 127
 128         if (!nr)
 129                 return 0;
 130         data_len = btrfs_item_end(l->items + start);
 131         data_len = data_len - btrfs_item_offset(l->items + end);
 132         data_len += sizeof(struct btrfs_item) * nr;
 133         return data_len;
 134 }
 135
 136 /*
 137  * The space between the end of the leaf items and
 138  * the start of the leaf data.  IOW, how much room
 139  * the leaf has left for both items and data
 140  */
 141 int btrfs_leaf_free_space(struct btrfs_root *root, struct btrfs_leaf *leaf)
 142 {
 143         int nritems = btrfs_header_nritems(&leaf->header);
 144         return BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
 145 }
 146
 147 /*
 148  * compare two keys in a memcmp fashion
 149  */
 150 int btrfs_comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 151 {
 152         struct btrfs_key k1;
 153
 154         btrfs_disk_key_to_cpu(&k1, disk);
 155
 156         if (k1.objectid > k2->objectid)
 157                 return 1;
 158         if (k1.objectid < k2->objectid)
 159                 return -1;
 160         if (k1.type > k2->type)
 161                 return 1;
 162         if (k1.type < k2->type)
 163                 return -1;
 164         if (k1.offset > k2->offset)
 165                 return 1;
 166         if (k1.offset < k2->offset)
 167                 return -1;
 168         return 0;
 169 }
 170
 171 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 172                       int level)
 173 {
 174         int i;
 175         struct btrfs_node *parent = NULL;
 176         struct btrfs_node *node = &path->nodes[level]->node;
 177         int parent_slot;
 178         u32 nritems = btrfs_header_nritems(&node->header);
 179
 180         if (path->nodes[level + 1])
 181                 parent = &path->nodes[level + 1]->node;
 182         parent_slot = path->slots[level + 1];
 183         BUG_ON(nritems == 0);
 184         if (parent) {
 185                 struct btrfs_disk_key *parent_key;
 186                 parent_key = &parent->ptrs[parent_slot].key;
 187                 BUG_ON(memcmp(parent_key, &node->ptrs[0].key,
 188                               sizeof(struct btrfs_disk_key)));
 189                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 190                        btrfs_header_bytenr(&node->header));
 191         }
 192         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 193         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 194                 struct btrfs_key cpukey;
 195                 btrfs_disk_key_to_cpu(&cpukey, &node->ptrs[i + 1].key);
 196                 BUG_ON(btrfs_comp_keys(&node->ptrs[i].key, &cpukey) >= 0);
 197         }
 198         return 0;
 199 }
 200
 201 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 202                       int level)
 203 {
 204         int i;
 205         struct btrfs_leaf *leaf = &path->nodes[level]->leaf;
 206         struct btrfs_node *parent = NULL;
 207         int parent_slot;
 208         u32 nritems = btrfs_header_nritems(&leaf->header);
 209
 210         if (path->nodes[level + 1])
 211                 parent = &path->nodes[level + 1]->node;
 212         parent_slot = path->slots[level + 1];
 213         BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
 214
 215         if (nritems == 0)
 216                 return 0;
 217
 218         if (parent) {
 219                 struct btrfs_disk_key *parent_key;
 220                 parent_key = &parent->ptrs[parent_slot].key;
 221                 BUG_ON(memcmp(parent_key, &leaf->items[0].key,
 222                        sizeof(struct btrfs_disk_key)));
 223                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 224                        btrfs_header_bytenr(&leaf->header));
 225         }
 226         for (i = 0; nritems > 1 && i < nritems - 2; i++) {
 227                 struct btrfs_key cpukey;
 228                 btrfs_disk_key_to_cpu(&cpukey, &leaf->items[i + 1].key);
 229                 BUG_ON(btrfs_comp_keys(&leaf->items[i].key,
 230                                  &cpukey) >= 0);
 231                 BUG_ON(btrfs_item_offset(leaf->items + i) !=
 232                         btrfs_item_end(leaf->items + i + 1));
 233                 if (i == 0) {
 234                         BUG_ON(btrfs_item_offset(leaf->items + i) +
 235                                btrfs_item_size(leaf->items + i) !=
 236                                BTRFS_LEAF_DATA_SIZE(root));
 237                 }
 238         }
 239         return 0;
 240 }
 241
 242 static int check_block(struct btrfs_root *root, struct btrfs_path *path,
 243                         int level)
 244 {
 245         if (level == 0)
 246                 return check_leaf(root, path, level);
 247         return check_node(root, path, level);
 248 }
 249
 250 /*
 251  * search for key in the array p.  items p are item_size apart
 252  * and there are 'max' items in p
 253  * the slot in the array is returned via slot, and it points to
 254  * the place where you would insert key if it is not found in
 255  * the array.
 256  *
 257  * slot may point to max if the key is bigger than all of the keys
 258  */
 259 static int generic_bin_search(char *p, int item_size, struct btrfs_key *key,
 260                        int max, int *slot)
 261 {
 262         int low = 0;
 263         int high = max;
 264         int mid;
 265         int ret;
 266         struct btrfs_disk_key *tmp;
 267
 268         while(low < high) {
 269                 mid = (low + high) / 2;
 270                 tmp = (struct btrfs_disk_key *)(p + mid * item_size);
 271                 ret = btrfs_comp_keys(tmp, key);
 272
 273                 if (ret < 0)
 274                         low = mid + 1;
 275                 else if (ret > 0)
 276                         high = mid;
 277                 else {
 278                         *slot = mid;
 279                         return 0;
 280                 }
 281         }
 282         *slot = low;
 283         return 1;
 284 }
 285
 286 /*
 287  * simple bin_search frontend that does the right thing for
 288  * leaves vs nodes
 289  */
 290 static int bin_search(struct btrfs_node *c, struct btrfs_key *key, int *slot)
 291 {
 292         if (btrfs_is_leaf(c)) {
 293                 struct btrfs_leaf *l = (struct btrfs_leaf *)c;
 294                 return generic_bin_search((void *)l->items,
 295                                           sizeof(struct btrfs_item),
 296                                           key, btrfs_header_nritems(&c->header),
 297                                           slot);
 298         } else {
 299                 return generic_bin_search((void *)c->ptrs,
 300                                           sizeof(struct btrfs_key_ptr),
 301                                           key, btrfs_header_nritems(&c->header),
 302                                           slot);
 303         }
 304         return -1;
 305 }
 306
 307 static struct btrfs_buffer *read_node_slot(struct btrfs_root *root,
 308                                    struct btrfs_buffer *parent_buf,
 309                                    int slot)
 310 {
 311         struct btrfs_node *node = &parent_buf->node;
 312         int level = btrfs_header_level(&node->header);
 313         if (slot < 0)
 314                 return NULL;
 315         if (slot >= btrfs_header_nritems(&node->header))
 316                 return NULL;
 317         return read_tree_block(root, btrfs_node_blockptr(node, slot),
 318                                btrfs_level_size(root, level - 1));
 319 }
 320
 321 static int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root
 322                          *root, struct btrfs_path *path, int level)
 323 {
 324         struct btrfs_buffer *right_buf;
 325         struct btrfs_buffer *mid_buf;
 326         struct btrfs_buffer *left_buf;
 327         struct btrfs_buffer *parent_buf = NULL;
 328         struct btrfs_node *right = NULL;
 329         struct btrfs_node *mid;
 330         struct btrfs_node *left = NULL;
 331         struct btrfs_node *parent = NULL;
 332         int ret = 0;
 333         int wret;
 334         int pslot;
 335         int orig_slot = path->slots[level];
 336         u64 orig_ptr;
 337
 338         if (level == 0)
 339                 return 0;
 340
 341         mid_buf = path->nodes[level];
 342         mid = &mid_buf->node;
 343         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 344
 345         if (level < BTRFS_MAX_LEVEL - 1)
 346                 parent_buf = path->nodes[level + 1];
 347         pslot = path->slots[level + 1];
 348
 349         /*
 350          * deal with the case where there is only one pointer in the root
 351          * by promoting the node below to a root
 352          */
 353         if (!parent_buf) {
 354                 struct btrfs_buffer *child;
 355                 u64 bytenr = mid_buf->bytenr;
 356
 357                 if (btrfs_header_nritems(&mid->header) != 1)
 358                         return 0;
 359
 360                 /* promote the child to a root */
 361                 child = read_node_slot(root, mid_buf, 0);
 362                 BUG_ON(!child);
 363                 root->node = child;
 364                 path->nodes[level] = NULL;
 365                 /* once for the path */
 366                 btrfs_block_release(root, mid_buf);
 367                 /* once for the root ptr */
 368                 btrfs_block_release(root, mid_buf);
 369                 clean_tree_block(trans, root, mid_buf);
 370                 return btrfs_free_extent(trans, root, bytenr, root->nodesize,
 371                                          root->root_key.objectid,
 372                                          btrfs_header_generation(&mid->header),
 373                                          0, 0, 1);
 374         }
 375         parent = &parent_buf->node;
 376
 377         if (btrfs_header_nritems(&mid->header) >
 378             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 379                 return 0;
 380
 381         left_buf = read_node_slot(root, parent_buf, pslot - 1);
 382         right_buf = read_node_slot(root, parent_buf, pslot + 1);
 383
 384         /* first, try to make some room in the middle buffer */
 385         if (left_buf) {
 386                 btrfs_cow_block(trans, root, left_buf, parent_buf, pslot - 1,
 387                                 &left_buf);
 388                 left = &left_buf->node;
 389                 orig_slot += btrfs_header_nritems(&left->header);
 390                 wret = push_node_left(trans, root, left_buf, mid_buf);
 391                 if (wret < 0)
 392                         ret = wret;
 393         }
 394
 395         /*
 396          * then try to empty the right most buffer into the middle
 397          */
 398         if (right_buf) {
 399                 btrfs_cow_block(trans, root, right_buf, parent_buf, pslot + 1,
 400                                 &right_buf);
 401                 right = &right_buf->node;
 402                 wret = push_node_left(trans, root, mid_buf, right_buf);
 403                 if (wret < 0)
 404                         ret = wret;
 405                 if (btrfs_header_nritems(&right->header) == 0) {
 406                         u64 generation;
 407                         u64 bytenr = right_buf->bytenr;
 408
 409                         generation = btrfs_header_generation(&parent->header);
 410                         btrfs_block_release(root, right_buf);
 411                         clean_tree_block(trans, root, right_buf);
 412                         right_buf = NULL;
 413                         right = NULL;
 414                         wret = del_ptr(trans, root, path, level + 1, pslot +
 415                                        1);
 416                         if (wret)
 417                                 ret = wret;
 418                         wret = btrfs_free_extent(trans, root, bytenr,
 419                                                  root->nodesize,
 420                                                  root->root_key.objectid,
 421                                                  generation, 0, 0, 1);
 422                         if (wret)
 423                                 ret = wret;
 424                 } else {
 425                         memcpy(&parent->ptrs[pslot + 1].key,
 426                                 &right->ptrs[0].key,
 427                                 sizeof(struct btrfs_disk_key));
 428                         BUG_ON(list_empty(&parent_buf->dirty));
 429                 }
 430         }
 431         if (btrfs_header_nritems(&mid->header) == 1) {
 432                 /*
 433                  * we're not allowed to leave a node with one item in the
 434                  * tree during a delete.  A deletion from lower in the tree
 435                  * could try to delete the only pointer in this node.
 436                  * So, pull some keys from the left.
 437                  * There has to be a left pointer at this point because
 438                  * otherwise we would have pulled some pointers from the
 439                  * right
 440                  */
 441                 BUG_ON(!left_buf);
 442                 wret = balance_node_right(trans, root, mid_buf, left_buf);
 443                 if (wret < 0)
 444                         ret = wret;
 445                 BUG_ON(wret == 1);
 446         }
 447         if (btrfs_header_nritems(&mid->header) == 0) {
 448                 /* we've managed to empty the middle node, drop it */
 449                 u64 bytenr = mid_buf->bytenr;
 450                 u64 generation;
 451
 452                 generation = btrfs_header_generation(&parent->header);
 453                 btrfs_block_release(root, mid_buf);
 454                 clean_tree_block(trans, root, mid_buf);
 455                 mid_buf = NULL;
 456                 mid = NULL;
 457                 wret = del_ptr(trans, root, path, level + 1, pslot);
 458                 if (wret)
 459                         ret = wret;
 460                 wret = btrfs_free_extent(trans, root, bytenr, root->nodesize,
 461                                          root->root_key.objectid,
 462                                          generation, 0, 0, 1);
 463                 if (wret)
 464                         ret = wret;
 465         } else {
 466                 /* update the parent key to reflect our changes */
 467                 memcpy(&parent->ptrs[pslot].key, &mid->ptrs[0].key,
 468                        sizeof(struct btrfs_disk_key));
 469                 BUG_ON(list_empty(&parent_buf->dirty));
 470         }
 471
 472         /* update the path */
 473         if (left_buf) {
 474                 if (btrfs_header_nritems(&left->header) > orig_slot) {
 475                         left_buf->count++; // released below
 476                         path->nodes[level] = left_buf;
 477                         path->slots[level + 1] -= 1;
 478                         path->slots[level] = orig_slot;
 479                         if (mid_buf)
 480                                 btrfs_block_release(root, mid_buf);
 481                 } else {
 482                         orig_slot -= btrfs_header_nritems(&left->header);
 483                         path->slots[level] = orig_slot;
 484                 }
 485         }
 486         /* double check we haven't messed things up */
 487         check_block(root, path, level);
 488         if (orig_ptr != btrfs_node_blockptr(&path->nodes[level]->node,
 489                                             path->slots[level]))
 490                 BUG();
 491
 492         if (right_buf)
 493                 btrfs_block_release(root, right_buf);
 494         if (left_buf)
 495                 btrfs_block_release(root, left_buf);
 496         return ret;
 497 }
 498 static int push_nodes_for_insert(struct btrfs_trans_handle *trans,
 499                                 struct btrfs_root *root,
 500                                 struct btrfs_path *path, int level)
 501 {
 502         struct btrfs_node *right;
 503         struct btrfs_node *mid;
 504         struct btrfs_node *left;
 505         struct btrfs_node *parent;
 506         struct btrfs_buffer *right_buf;
 507         struct btrfs_buffer *mid_buf;
 508         struct btrfs_buffer *left_buf;
 509         struct btrfs_buffer *parent_buf = NULL;
 510         int ret = 0;
 511         int wret;
 512         int pslot;
 513         int orig_slot = path->slots[level];
 514         u64 orig_ptr;
 515
 516         if (level == 0)
 517                 return 1;
 518
 519         mid_buf = path->nodes[level];
 520         mid = &mid_buf->node;
 521         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 522
 523         if (level < BTRFS_MAX_LEVEL - 1)
 524                 parent_buf = path->nodes[level + 1];
 525         pslot = path->slots[level + 1];
 526
 527         if (!parent_buf)
 528                 return 1;
 529         parent = &parent_buf->node;
 530
 531         left_buf = read_node_slot(root, parent_buf, pslot - 1);
 532         left = &left_buf->node;
 533
 534         /* first, try to make some room in the middle buffer */
 535         if (left_buf) {
 536                 u32 left_nr;
 537                 left_nr = btrfs_header_nritems(&left->header);
 538                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 539                         wret = 1;
 540                 } else {
 541                         ret = btrfs_cow_block(trans, root, left_buf,
 542                                               parent_buf, pslot - 1,
 543                                               &left_buf);
 544                         left = &left_buf->node;
 545                         if (ret)
 546                                 wret = 1;
 547                         else {
 548                                 wret = push_node_left(trans, root,
 549                                                       left_buf, mid_buf);
 550                         }
 551                 }
 552                 if (wret < 0)
 553                         ret = wret;
 554                 if (wret == 0) {
 555                         orig_slot += left_nr;
 556                         memcpy(&parent->ptrs[pslot].key, &mid->ptrs[0].key,
 557                                 sizeof(struct btrfs_disk_key));
 558                         BUG_ON(list_empty(&parent_buf->dirty));
 559                         if (btrfs_header_nritems(&left->header) > orig_slot) {
 560                                 path->nodes[level] = left_buf;
 561                                 path->slots[level + 1] -= 1;
 562                                 path->slots[level] = orig_slot;
 563                                 btrfs_block_release(root, mid_buf);
 564                         } else {
 565                                 orig_slot -=
 566                                         btrfs_header_nritems(&left->header);
 567                                 path->slots[level] = orig_slot;
 568                                 btrfs_block_release(root, left_buf);
 569                         }
 570                         return 0;
 571                 }
 572                 btrfs_block_release(root, left_buf);
 573         }
 574
 575         right_buf = read_node_slot(root, parent_buf, pslot + 1);
 576         right = &right_buf->node;
 577
 578         /*
 579          * then try to empty the right most buffer into the middle
 580          */
 581         if (right_buf) {
 582                 u32 right_nr;
 583                 right_nr = btrfs_header_nritems(&right->header);
 584                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 585                         wret = 1;
 586                 } else {
 587                         ret = btrfs_cow_block(trans, root, right_buf,
 588                                               parent_buf, pslot + 1,
 589                                               &right_buf);
 590                         right = &right_buf->node;
 591                         if (ret)
 592                                 wret = 1;
 593                         else {
 594                                 wret = balance_node_right(trans, root,
 595                                                 right_buf, mid_buf);
 596                         }
 597                 }
 598                 if (wret < 0)
 599                         ret = wret;
 600                 if (wret == 0) {
 601                         memcpy(&parent->ptrs[pslot + 1].key,
 602                                &right->ptrs[0].key,
 603                                sizeof(struct btrfs_disk_key));
 604                         BUG_ON(list_empty(&parent_buf->dirty));
 605                         if (btrfs_header_nritems(&mid->header) <= orig_slot) {
 606                                 path->nodes[level] = right_buf;
 607                                 path->slots[level + 1] += 1;
 608                                 path->slots[level] = orig_slot -
 609                                         btrfs_header_nritems(&mid->header);
 610                                 btrfs_block_release(root, mid_buf);
 611                         } else {
 612                                 btrfs_block_release(root, right_buf);
 613                         }
 614                         return 0;
 615                 }
 616                 btrfs_block_release(root, right_buf);
 617         }
 618         return 1;
 619 }
 620
 621 /*
 622  * look for key in the tree.  path is filled in with nodes along the way
 623  * if key is found, we return zero and you can find the item in the leaf
 624  * level of the path (level 0)
 625  *
 626  * If the key isn't found, the path points to the slot where it should
 627  * be inserted, and 1 is returned.  If there are other errors during the
 628  * search a negative error number is returned.
 629  *
 630  * if ins_len > 0, nodes and leaves will be split as we walk down the
 631  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
 632  * possible)
 633  */
 634 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 635                       *root, struct btrfs_key *key, struct btrfs_path *p, int
 636                       ins_len, int cow)
 637 {
 638         struct btrfs_buffer *b;
 639         struct btrfs_node *c;
 640         int slot;
 641         int ret;
 642         int level;
 643
 644 again:
 645         b = root->node;
 646         b->count++;
 647         while (b) {
 648                 level = btrfs_header_level(&b->node.header);
 649                 if (cow) {
 650                         int wret;
 651                         wret = btrfs_cow_block(trans, root, b,
 652                                               p->nodes[level + 1],
 653                                               p->slots[level + 1],
 654                                               &b);
 655                         if (wret) {
 656                                 btrfs_block_release(root, b);
 657                                 return wret;
 658                         }
 659                 }
 660                 BUG_ON(!cow && ins_len);
 661                 c = &b->node;
 662                 p->nodes[level] = b;
 663                 ret = check_block(root, p, level);
 664                 if (ret)
 665                         return -1;
 666                 ret = bin_search(c, key, &slot);
 667                 if (!btrfs_is_leaf(c)) {
 668                         if (ret && slot > 0)
 669                                 slot -= 1;
 670                         p->slots[level] = slot;
 671                         if (ins_len > 0 && btrfs_header_nritems(&c->header) >=
 672                             BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 673                                 int sret = split_node(trans, root, p, level);
 674                                 BUG_ON(sret > 0);
 675                                 if (sret)
 676                                         return sret;
 677                                 b = p->nodes[level];
 678                                 c = &b->node;
 679                                 slot = p->slots[level];
 680                         } else if (ins_len < 0) {
 681                                 int sret = balance_level(trans, root, p,
 682                                                          level);
 683                                 if (sret)
 684                                         return sret;
 685                                 b = p->nodes[level];
 686                                 if (!b) {
 687                                         btrfs_release_path(NULL, p);
 688                                         goto again;
 689                                 }
 690                                 c = &b->node;
 691                                 slot = p->slots[level];
 692                                 BUG_ON(btrfs_header_nritems(&c->header) == 1);
 693                         }
 694                         b = read_tree_block(root,
 695                                             btrfs_node_blockptr(c, slot),
 696                                             btrfs_level_size(root, level - 1));
 697                 } else {
 698                         struct btrfs_leaf *l = (struct btrfs_leaf *)c;
 699                         p->slots[level] = slot;
 700                         if (ins_len > 0 && btrfs_leaf_free_space(root, l) <
 701                             sizeof(struct btrfs_item) + ins_len) {
 702                                 int sret = split_leaf(trans, root, key,
 703                                                       p, ins_len, ret == 0);
 704                                 BUG_ON(sret > 0);
 705                                 if (sret)
 706                                         return sret;
 707                         }
 708                         BUG_ON(root->node->count == 1);
 709                         return ret;
 710                 }
 711         }
 712         BUG_ON(root->node->count == 1);
 713         return 1;
 714 }
 715
 716 /*
 717  * adjust the pointers going up the tree, starting at level
 718  * making sure the right key of each node is points to 'key'.
 719  * This is used after shifting pointers to the left, so it stops
 720  * fixing up pointers when a given leaf/node is not in slot 0 of the
 721  * higher levels
 722  *
 723  * If this fails to write a tree block, it returns -1, but continues
 724  * fixing up the blocks in ram so the tree is consistent.
 725  */
 726 static int fixup_low_keys(struct btrfs_trans_handle *trans, struct btrfs_root
 727                           *root, struct btrfs_path *path, struct btrfs_disk_key
 728                           *key, int level)
 729 {
 730         int i;
 731         int ret = 0;
 732         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
 733                 struct btrfs_node *t;
 734                 int tslot = path->slots[i];
 735                 if (!path->nodes[i])
 736                         break;
 737                 t = &path->nodes[i]->node;
 738                 memcpy(&t->ptrs[tslot].key, key, sizeof(*key));
 739                 BUG_ON(list_empty(&path->nodes[i]->dirty));
 740                 if (tslot != 0)
 741                         break;
 742         }
 743         return ret;
 744 }
 745
 746 /*
 747  * try to push data from one node into the next node left in the
 748  * tree.
 749  *
 750  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
 751  * error, and > 0 if there was no room in the left hand block.
 752  */
 753 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
 754                           *root, struct btrfs_buffer *dst_buf, struct
 755                           btrfs_buffer *src_buf)
 756 {
 757         struct btrfs_node *src = &src_buf->node;
 758         struct btrfs_node *dst = &dst_buf->node;
 759         int push_items = 0;
 760         int src_nritems;
 761         int dst_nritems;
 762         int ret = 0;
 763
 764         src_nritems = btrfs_header_nritems(&src->header);
 765         dst_nritems = btrfs_header_nritems(&dst->header);
 766         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
 767         if (push_items <= 0) {
 768                 return 1;
 769         }
 770
 771         if (src_nritems < push_items)
 772                 push_items = src_nritems;
 773
 774         memcpy(dst->ptrs + dst_nritems, src->ptrs,
 775                 push_items * sizeof(struct btrfs_key_ptr));
 776         if (push_items < src_nritems) {
 777                 memmove(src->ptrs, src->ptrs + push_items,
 778                         (src_nritems - push_items) *
 779                         sizeof(struct btrfs_key_ptr));
 780         }
 781         btrfs_set_header_nritems(&src->header, src_nritems - push_items);
 782         btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
 783         BUG_ON(list_empty(&src_buf->dirty));
 784         BUG_ON(list_empty(&dst_buf->dirty));
 785         return ret;
 786 }
 787
 788 /*
 789  * try to push data from one node into the next node right in the
 790  * tree.
 791  *
 792  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
 793  * error, and > 0 if there was no room in the right hand block.
 794  *
 795  * this will  only push up to 1/2 the contents of the left node over
 796  */
 797 static int balance_node_right(struct btrfs_trans_handle *trans, struct
 798                               btrfs_root *root, struct btrfs_buffer *dst_buf,
 799                               struct btrfs_buffer *src_buf)
 800 {
 801         struct btrfs_node *src = &src_buf->node;
 802         struct btrfs_node *dst = &dst_buf->node;
 803         int push_items = 0;
 804         int max_push;
 805         int src_nritems;
 806         int dst_nritems;
 807         int ret = 0;
 808
 809         src_nritems = btrfs_header_nritems(&src->header);
 810         dst_nritems = btrfs_header_nritems(&dst->header);
 811         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
 812         if (push_items <= 0) {
 813                 return 1;
 814         }
 815         max_push = src_nritems / 2 + 1;
 816         /* don't try to empty the node */
 817         if (max_push >= src_nritems)
 818                 return 1;
 819         if (max_push < push_items)
 820                 push_items = max_push;
 821
 822         memmove(dst->ptrs + push_items, dst->ptrs,
 823                 dst_nritems * sizeof(struct btrfs_key_ptr));
 824         memcpy(dst->ptrs, src->ptrs + src_nritems - push_items,
 825                 push_items * sizeof(struct btrfs_key_ptr));
 826
 827         btrfs_set_header_nritems(&src->header, src_nritems - push_items);
 828         btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
 829
 830         BUG_ON(list_empty(&src_buf->dirty));
 831         BUG_ON(list_empty(&dst_buf->dirty));
 832         return ret;
 833 }
 834
 835 /*
 836  * helper function to insert a new root level in the tree.
 837  * A new node is allocated, and a single item is inserted to
 838  * point to the existing root
 839  *
 840  * returns zero on success or < 0 on failure.
 841  */
 842 static int insert_new_root(struct btrfs_trans_handle *trans, struct btrfs_root
 843                            *root, struct btrfs_path *path, int level)
 844 {
 845         struct btrfs_buffer *t;
 846         struct btrfs_node *lower;
 847         struct btrfs_node *c;
 848         struct btrfs_disk_key *lower_key;
 849
 850         BUG_ON(path->nodes[level]);
 851         BUG_ON(path->nodes[level-1] != root->node);
 852         t = btrfs_alloc_free_block(trans, root, root->nodesize);
 853         c = &t->node;
 854         memset(&c->header, 0, sizeof(c->header));
 855         btrfs_set_header_nritems(&c->header, 1);
 856         btrfs_set_header_level(&c->header, level);
 857         btrfs_set_header_bytenr(&c->header, t->bytenr);
 858         btrfs_set_header_generation(&c->header, trans->transid);
 859         btrfs_set_header_owner(&c->header, root->root_key.objectid);
 860         memcpy(c->header.fsid, root->fs_info->disk_super->fsid,
 861                sizeof(c->header.fsid));
 862         lower = &path->nodes[level-1]->node;
 863
 864         if (btrfs_is_leaf(lower))
 865                 lower_key = &((struct btrfs_leaf *)lower)->items[0].key;
 866         else
 867                 lower_key = &lower->ptrs[0].key;
 868         memcpy(&c->ptrs[0].key, lower_key, sizeof(struct btrfs_disk_key));
 869         btrfs_set_node_blockptr(c, 0, path->nodes[level - 1]->bytenr);
 870         BUG_ON(list_empty(&t->dirty));
 871         btrfs_set_node_ptr_generation(c, 0,
 872                  btrfs_header_generation(&path->nodes[level - 1]->node.header));
 873         /* the super has an extra ref to root->node */
 874         btrfs_block_release(root, root->node);
 875         root->node = t;
 876         t->count++;
 877         path->nodes[level] = t;
 878         path->slots[level] = 0;
 879         return 0;
 880 }
 881
 882 /*
 883  * worker function to insert a single pointer in a node.
 884  * the node should have enough room for the pointer already
 885  *
 886  * slot and level indicate where you want the key to go, and
 887  * bytenr is the block the key points to.
 888  *
 889  * returns zero on success and < 0 on any error
 890  */
 891 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
 892                       *root, struct btrfs_path *path, struct btrfs_disk_key
 893                       *key, u64 bytenr, int slot, int level)
 894 {
 895         struct btrfs_node *lower;
 896         int nritems;
 897
 898         BUG_ON(!path->nodes[level]);
 899         lower = &path->nodes[level]->node;
 900         nritems = btrfs_header_nritems(&lower->header);
 901         if (slot > nritems)
 902                 BUG();
 903         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
 904                 BUG();
 905         if (slot != nritems) {
 906                 memmove(lower->ptrs + slot + 1, lower->ptrs + slot,
 907                         (nritems - slot) * sizeof(struct btrfs_key_ptr));
 908         }
 909         memcpy(&lower->ptrs[slot].key, key, sizeof(struct btrfs_disk_key));
 910         btrfs_set_node_blockptr(lower, slot, bytenr);
 911         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
 912         btrfs_set_header_nritems(&lower->header, nritems + 1);
 913         BUG_ON(list_empty(&path->nodes[level]->dirty));
 914         return 0;
 915 }
 916
 917 /*
 918  * split the node at the specified level in path in two.
 919  * The path is corrected to point to the appropriate node after the split
 920  *
 921  * Before splitting this tries to make some room in the node by pushing
 922  * left and right, if either one works, it returns right away.
 923  *
 924  * returns 0 on success and < 0 on failure
 925  */
 926 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
 927                       *root, struct btrfs_path *path, int level)
 928 {
 929         struct btrfs_buffer *t;
 930         struct btrfs_node *c;
 931         struct btrfs_buffer *split_buffer;
 932         struct btrfs_node *split;
 933         int mid;
 934         int ret;
 935         int wret;
 936         u32 c_nritems;
 937
 938         t = path->nodes[level];
 939         c = &t->node;
 940         if (t == root->node) {
 941                 /* trying to split the root, lets make a new one */
 942                 ret = insert_new_root(trans, root, path, level + 1);
 943                 if (ret)
 944                         return ret;
 945         } else {
 946                 ret = push_nodes_for_insert(trans, root, path, level);
 947                 t = path->nodes[level];
 948                 c = &t->node;
 949                 if (!ret && btrfs_header_nritems(&c->header) <
 950                     BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
 951                         return 0;
 952                 if (ret < 0)
 953                         return ret;
 954         }
 955         c_nritems = btrfs_header_nritems(&c->header);
 956         split_buffer = btrfs_alloc_free_block(trans, root, root->nodesize);
 957         split = &split_buffer->node;
 958         btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
 959         btrfs_set_header_level(&split->header, btrfs_header_level(&c->header));
 960         btrfs_set_header_bytenr(&split->header, split_buffer->bytenr);
 961         btrfs_set_header_generation(&split->header, trans->transid);
 962         btrfs_set_header_owner(&split->header, root->root_key.objectid);
 963         memcpy(split->header.fsid, root->fs_info->disk_super->fsid,
 964                sizeof(split->header.fsid));
 965         mid = (c_nritems + 1) / 2;
 966         memcpy(split->ptrs, c->ptrs + mid,
 967                 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
 968         btrfs_set_header_nritems(&split->header, c_nritems - mid);
 969         btrfs_set_header_nritems(&c->header, mid);
 970         ret = 0;
 971
 972         BUG_ON(list_empty(&t->dirty));
 973         wret = insert_ptr(trans, root, path, &split->ptrs[0].key,
 974                           split_buffer->bytenr, path->slots[level + 1] + 1,
 975                           level + 1);
 976         if (wret)
 977                 ret = wret;
 978
 979         if (path->slots[level] >= mid) {
 980                 path->slots[level] -= mid;
 981                 btrfs_block_release(root, t);
 982                 path->nodes[level] = split_buffer;
 983                 path->slots[level + 1] += 1;
 984         } else {
 985                 btrfs_block_release(root, split_buffer);
 986         }
 987         return ret;
 988 }
 989
 990 /*
 991  * push some data in the path leaf to the right, trying to free up at
 992  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
 993  *
 994  * returns 1 if the push failed because the other node didn't have enough
 995  * room, 0 if everything worked out and < 0 if there were major errors.
 996  */
 997 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
 998                            *root, struct btrfs_path *path, int data_size,
 999                            int empty)
1000 {
1001         struct btrfs_buffer *left_buf = path->nodes[0];
1002         struct btrfs_leaf *left = &left_buf->leaf;
1003         struct btrfs_leaf *right;
1004         struct btrfs_buffer *right_buf;
1005         struct btrfs_buffer *upper;
1006         int slot;
1007         u32 i;
1008         int free_space;
1009         int push_space = 0;
1010         int push_items = 0;
1011         struct btrfs_item *item;
1012         u32 left_nritems;
1013         u32 nr;
1014         u32 right_nritems;
1015         slot = path->slots[1];
1016         if (!path->nodes[1]) {
1017                 return 1;
1018         }
1019         upper = path->nodes[1];
1020         if (slot >= btrfs_header_nritems(&upper->node.header) - 1) {
1021                 return 1;
1022         }
1023         right_buf = read_tree_block(root,
1024                             btrfs_node_blockptr(&upper->node, slot + 1),
1025                             root->leafsize);
1026         right = &right_buf->leaf;
1027         free_space = btrfs_leaf_free_space(root, right);
1028         if (free_space < data_size + sizeof(struct btrfs_item)) {
1029                 btrfs_block_release(root, right_buf);
1030                 return 1;
1031         }
1032         /* cow and double check */
1033         btrfs_cow_block(trans, root, right_buf, upper, slot + 1, &right_buf);
1034         right = &right_buf->leaf;
1035         free_space = btrfs_leaf_free_space(root, right);
1036         if (free_space < data_size + sizeof(struct btrfs_item)) {
1037                 btrfs_block_release(root, right_buf);
1038                 return 1;
1039         }
1040         left_nritems = btrfs_header_nritems(&left->header);
1041         if (left_nritems == 0) {
1042                 btrfs_block_release(root, right_buf);
1043                 return 1;
1044         }
1045
1046         if (empty)
1047                 nr = 0;
1048         else
1049                 nr = 1;
1050
1051         i = left_nritems - 1;
1052         while (i >= nr) {
1053                 item = left->items + i;
1054                 if (path->slots[0] == i)
1055                         push_space += data_size + sizeof(*item);
1056                 if (btrfs_item_size(item) + sizeof(*item) + push_space >
1057                     free_space)
1058                         break;
1059                 push_items++;
1060                 push_space += btrfs_item_size(item) + sizeof(*item);
1061                 if (i == 0)
1062                         break;
1063                 i--;
1064         }
1065         if (push_items == 0) {
1066                 btrfs_block_release(root, right_buf);
1067                 return 1;
1068         }
1069         right_nritems = btrfs_header_nritems(&right->header);
1070         /* push left to right */
1071         push_space = btrfs_item_end(left->items + left_nritems - push_items);
1072         push_space -= leaf_data_end(root, left);
1073         /* make room in the right data area */
1074         memmove(btrfs_leaf_data(right) + leaf_data_end(root, right) -
1075                 push_space, btrfs_leaf_data(right) + leaf_data_end(root, right),
1076                 BTRFS_LEAF_DATA_SIZE(root) - leaf_data_end(root, right));
1077         /* copy from the left data area */
1078         memcpy(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) - push_space,
1079                 btrfs_leaf_data(left) + leaf_data_end(root, left), push_space);
1080         memmove(right->items + push_items, right->items,
1081                 right_nritems * sizeof(struct btrfs_item));
1082         /* copy the items from left to right */
1083         memcpy(right->items, left->items + left_nritems - push_items,
1084                 push_items * sizeof(struct btrfs_item));
1085
1086         /* update the item pointers */
1087         right_nritems += push_items;
1088         btrfs_set_header_nritems(&right->header, right_nritems);
1089         push_space = BTRFS_LEAF_DATA_SIZE(root);
1090         for (i = 0; i < right_nritems; i++) {
1091                 btrfs_set_item_offset(right->items + i, push_space -
1092                                       btrfs_item_size(right->items + i));
1093                 push_space = btrfs_item_offset(right->items + i);
1094         }
1095         left_nritems -= push_items;
1096         btrfs_set_header_nritems(&left->header, left_nritems);
1097
1098         BUG_ON(list_empty(&left_buf->dirty));
1099         BUG_ON(list_empty(&right_buf->dirty));
1100         memcpy(&upper->node.ptrs[slot + 1].key,
1101                 &right->items[0].key, sizeof(struct btrfs_disk_key));
1102         BUG_ON(list_empty(&upper->dirty));
1103
1104         /* then fixup the leaf pointer in the path */
1105         if (path->slots[0] >= left_nritems) {
1106                 path->slots[0] -= left_nritems;
1107                 btrfs_block_release(root, path->nodes[0]);
1108                 path->nodes[0] = right_buf;
1109                 path->slots[1] += 1;
1110         } else {
1111                 btrfs_block_release(root, right_buf);
1112         }
1113         return 0;
1114 }
1115 /*
1116  * push some data in the path leaf to the left, trying to free up at
1117  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1118  */
1119 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1120                           *root, struct btrfs_path *path, int data_size,
1121                           int empty)
1122 {
1123         struct btrfs_buffer *right_buf = path->nodes[0];
1124         struct btrfs_leaf *right = &right_buf->leaf;
1125         struct btrfs_buffer *t;
1126         struct btrfs_leaf *left;
1127         int slot;
1128         int i;
1129         int free_space;
1130         int push_space = 0;
1131         int push_items = 0;
1132         struct btrfs_item *item;
1133         u32 old_left_nritems;
1134         u32 right_nritems;
1135         u32 nr;
1136         int ret = 0;
1137         int wret;
1138         slot = path->slots[1];
1139         if (slot == 0) {
1140                 return 1;
1141         }
1142         if (!path->nodes[1]) {
1143                 return 1;
1144         }
1145         right_nritems = btrfs_header_nritems(&right->header);
1146         if (right_nritems == 0) {
1147                 return 1;
1148         }
1149
1150         t = read_tree_block(root,
1151                     btrfs_node_blockptr(&path->nodes[1]->node, slot - 1),
1152                     root->leafsize);
1153         left = &t->leaf;
1154         free_space = btrfs_leaf_free_space(root, left);
1155         if (free_space < data_size + sizeof(struct btrfs_item)) {
1156                 btrfs_block_release(root, t);
1157                 return 1;
1158         }
1159
1160         /* cow and double check */
1161         btrfs_cow_block(trans, root, t, path->nodes[1], slot - 1, &t);
1162         left = &t->leaf;
1163         free_space = btrfs_leaf_free_space(root, left);
1164         if (free_space < data_size + sizeof(struct btrfs_item)) {
1165                 btrfs_block_release(root, t);
1166                 return 1;
1167         }
1168         if (empty)
1169                 nr = right_nritems;
1170         else
1171                 nr = right_nritems - 1;
1172
1173         for (i = 0; i < nr; i++) {
1174                 item = right->items + i;
1175                 if (path->slots[0] == i)
1176                         push_space += data_size + sizeof(*item);
1177                 if (btrfs_item_size(item) + sizeof(*item) + push_space >
1178                     free_space)
1179                         break;
1180                 push_items++;
1181                 push_space += btrfs_item_size(item) + sizeof(*item);
1182         }
1183         if (push_items == 0) {
1184                 btrfs_block_release(root, t);
1185                 return 1;
1186         }
1187         /* push data from right to left */
1188         memcpy(left->items + btrfs_header_nritems(&left->header),
1189                 right->items, push_items * sizeof(struct btrfs_item));
1190         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1191                      btrfs_item_offset(right->items + push_items -1);
1192         memcpy(btrfs_leaf_data(left) + leaf_data_end(root, left) - push_space,
1193                 btrfs_leaf_data(right) +
1194                 btrfs_item_offset(right->items + push_items - 1),
1195                 push_space);
1196         old_left_nritems = btrfs_header_nritems(&left->header);
1197         BUG_ON(old_left_nritems < 0);
1198
1199         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1200                 u32 ioff = btrfs_item_offset(left->items + i);
1201                 btrfs_set_item_offset(left->items + i, ioff -
1202                                      (BTRFS_LEAF_DATA_SIZE(root) -
1203                                       btrfs_item_offset(left->items +
1204                                                         old_left_nritems - 1)));
1205         }
1206         btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
1207         /* fixup right node */
1208         if (push_items < right_nritems) {
1209                 push_space = btrfs_item_offset(right->items + push_items - 1) -
1210                                                leaf_data_end(root, right);
1211                 memmove(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1212                         push_space, btrfs_leaf_data(right) +
1213                         leaf_data_end(root, right), push_space);
1214                 memmove(right->items, right->items + push_items,
1215                         (right_nritems - push_items) *
1216                         sizeof(struct btrfs_item));
1217         }
1218         right_nritems -= push_items;
1219         btrfs_set_header_nritems(&right->header, right_nritems);
1220         push_space = BTRFS_LEAF_DATA_SIZE(root);
1221         for (i = 0; i < right_nritems; i++) {
1222                 btrfs_set_item_offset(right->items + i, push_space -
1223                                       btrfs_item_size(right->items + i));
1224                 push_space = btrfs_item_offset(right->items + i);
1225         }
1226
1227         BUG_ON(list_empty(&t->dirty));
1228         BUG_ON(list_empty(&right_buf->dirty));
1229
1230         wret = fixup_low_keys(trans, root, path, &right->items[0].key, 1);
1231         if (wret)
1232                 ret = wret;
1233
1234         /* then fixup the leaf pointer in the path */
1235         if (path->slots[0] < push_items) {
1236                 path->slots[0] += old_left_nritems;
1237                 btrfs_block_release(root, path->nodes[0]);
1238                 path->nodes[0] = t;
1239                 path->slots[1] -= 1;
1240         } else {
1241                 btrfs_block_release(root, t);
1242                 path->slots[0] -= push_items;
1243         }
1244         BUG_ON(path->slots[0] < 0);
1245         return ret;
1246 }
1247
1248 /*
1249  * split the path's leaf in two, making sure there is at least data_size
1250  * available for the resulting leaf level of the path.
1251  *
1252  * returns 0 if all went well and < 0 on failure.
1253  */
1254 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1255                       *root, struct btrfs_key *ins_key,
1256                       struct btrfs_path *path, int data_size, int extend)
1257 {
1258         struct btrfs_buffer *l_buf;
1259         struct btrfs_leaf *l;
1260         u32 nritems;
1261         int mid;
1262         int slot;
1263         struct btrfs_leaf *right;
1264         struct btrfs_buffer *right_buffer;
1265         int space_needed = data_size + sizeof(struct btrfs_item);
1266         int data_copy_size;
1267         int rt_data_off;
1268         int i;
1269         int ret = 0;
1270         int wret;
1271         int double_split;
1272         int num_doubles = 0;
1273         struct btrfs_disk_key disk_key;
1274
1275         if (extend)
1276                 space_needed = data_size;
1277         /* first try to make some room by pushing left and right */
1278         if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
1279                 wret = push_leaf_right(trans, root, path, data_size, 0);
1280                 if (wret < 0) {
1281                         return wret;
1282                 }
1283                 if (wret) {
1284                         wret = push_leaf_left(trans, root, path, data_size, 0);
1285                         if (wret < 0)
1286                                 return wret;
1287                 }
1288                 l_buf = path->nodes[0];
1289                 l = &l_buf->leaf;
1290
1291                 /* did the pushes work? */
1292                 if (btrfs_leaf_free_space(root, l) >= space_needed)
1293                         return 0;
1294         }
1295         if (!path->nodes[1]) {
1296                 ret = insert_new_root(trans, root, path, 1);
1297                 if (ret)
1298                         return ret;
1299         }
1300 again:
1301         double_split = 0;
1302         l_buf = path->nodes[0];
1303         l = &l_buf->leaf;
1304         slot = path->slots[0];
1305         nritems = btrfs_header_nritems(&l->header);
1306         mid = (nritems + 1)/ 2;
1307
1308         right_buffer = btrfs_alloc_free_block(trans, root, root->leafsize);
1309         right = &right_buffer->leaf;
1310         memset(&right->header, 0, sizeof(right->header));
1311         btrfs_set_header_bytenr(&right->header, right_buffer->bytenr);
1312         btrfs_set_header_level(&right->header, 0);
1313         btrfs_set_header_owner(&right->header, root->root_key.objectid);
1314         btrfs_set_header_generation(&right->header, trans->transid);
1315         memcpy(right->header.fsid, root->fs_info->disk_super->fsid,
1316                sizeof(right->header.fsid));
1317         if (mid <= slot) {
1318                 if (nritems == 1 ||
1319                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1320                         BTRFS_LEAF_DATA_SIZE(root)) {
1321                         if (slot >= nritems) {
1322                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1323                                 btrfs_set_header_nritems(&right->header, 0);
1324                                 wret = insert_ptr(trans, root, path,
1325                                                   &disk_key, right_buffer->bytenr,
1326                                                   path->slots[1] + 1, 1);
1327                                 if (wret)
1328                                         ret = wret;
1329                                 btrfs_block_release(root, path->nodes[0]);
1330                                 path->nodes[0] = right_buffer;
1331                                 path->slots[0] = 0;
1332                                 path->slots[1] += 1;
1333                                 return ret;
1334                         }
1335                         mid = slot;
1336                         if (mid != nritems &&
1337                             leaf_space_used(l, mid, nritems - mid) +
1338                             space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1339                                 double_split = 1;
1340                         }
1341                 }
1342         } else {
1343                 if (leaf_space_used(l, 0, mid) + space_needed >
1344                         BTRFS_LEAF_DATA_SIZE(root)) {
1345                         if (!extend && slot == 0) {
1346                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1347                                 btrfs_set_header_nritems(&right->header, 0);
1348                                 wret = insert_ptr(trans, root, path,
1349                                                   &disk_key,
1350                                                   right_buffer->bytenr,
1351                                                   path->slots[1], 1);
1352                                 if (wret)
1353                                         ret = wret;
1354                                 btrfs_block_release(root, path->nodes[0]);
1355                                 path->nodes[0] = right_buffer;
1356                                 path->slots[0] = 0;
1357                                 if (path->slots[1] == 0) {
1358                                         wret = fixup_low_keys(trans, root,
1359                                                    path, &disk_key, 1);
1360                                         if (wret)
1361                                                 ret = wret;
1362                                 }
1363                                 return ret;
1364                         } else if (extend && slot == 0) {
1365                                 mid = 1;
1366                         } else {
1367                                 mid = slot;
1368                                 if (mid != nritems &&
1369                                     leaf_space_used(l, mid, nritems - mid) +
1370                                     space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
1371                                         double_split = 1;
1372                                 }
1373                         }
1374                 }
1375         }
1376         nritems = nritems - mid;
1377         btrfs_set_header_nritems(&right->header, nritems);
1378         data_copy_size = btrfs_item_end(l->items +  mid) -
1379                          leaf_data_end(root, l);
1380         memcpy(right->items, l->items + mid,
1381                nritems * sizeof(struct btrfs_item));
1382         memcpy(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1383                 data_copy_size, btrfs_leaf_data(l) +
1384                 leaf_data_end(root, l), data_copy_size);
1385         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1386                       btrfs_item_end(l->items + mid);
1387         for (i = 0; i < nritems; i++) {
1388                 u32 ioff = btrfs_item_offset(right->items + i);
1389                 btrfs_set_item_offset(right->items + i, ioff + rt_data_off);
1390         }
1391
1392         btrfs_set_header_nritems(&l->header, mid);
1393         ret = 0;
1394         wret = insert_ptr(trans, root, path, &right->items[0].key,
1395                           right_buffer->bytenr, path->slots[1] + 1, 1);
1396         if (wret)
1397                 ret = wret;
1398
1399         BUG_ON(list_empty(&right_buffer->dirty));
1400         BUG_ON(list_empty(&l_buf->dirty));
1401         BUG_ON(path->slots[0] != slot);
1402         if (mid <= slot) {
1403                 btrfs_block_release(root, path->nodes[0]);
1404                 path->nodes[0] = right_buffer;
1405                 path->slots[0] -= mid;
1406                 path->slots[1] += 1;
1407         } else
1408                 btrfs_block_release(root, right_buffer);
1409
1410         BUG_ON(path->slots[0] < 0);
1411         if (double_split) {
1412                 BUG_ON(num_doubles != 0);
1413                 num_doubles++;
1414                 goto again;
1415         }
1416         return ret;
1417 }
1418 /*
1419  * Given a key and some data, insert an item into the tree.
1420  * This does all the path init required, making room in the tree if needed.
1421  */
1422 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
1423                             *root, struct btrfs_path *path, struct btrfs_key
1424                             *cpu_key, u32 data_size)
1425 {
1426         int ret = 0;
1427         int slot;
1428         int slot_orig;
1429         struct btrfs_leaf *leaf;
1430         struct btrfs_buffer *leaf_buf;
1431         u32 nritems;
1432         unsigned int data_end;
1433         struct btrfs_disk_key disk_key;
1434
1435         btrfs_cpu_key_to_disk(&disk_key, cpu_key);
1436
1437         /* create a root if there isn't one */
1438         if (!root->node)
1439                 BUG();
1440         ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
1441         if (ret == 0) {
1442                 return -EEXIST;
1443         }
1444         if (ret < 0)
1445                 goto out;
1446
1447         slot_orig = path->slots[0];
1448         leaf_buf = path->nodes[0];
1449         leaf = &leaf_buf->leaf;
1450
1451         nritems = btrfs_header_nritems(&leaf->header);
1452         data_end = leaf_data_end(root, leaf);
1453
1454         if (btrfs_leaf_free_space(root, leaf) <
1455             sizeof(struct btrfs_item) + data_size)
1456                 BUG();
1457
1458         slot = path->slots[0];
1459         BUG_ON(slot < 0);
1460         if (slot != nritems) {
1461                 int i;
1462                 unsigned int old_data = btrfs_item_end(leaf->items + slot);
1463
1464                 /*
1465                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
1466                  */
1467                 /* first correct the data pointers */
1468                 for (i = slot; i < nritems; i++) {
1469                         u32 ioff = btrfs_item_offset(leaf->items + i);
1470                         btrfs_set_item_offset(leaf->items + i,
1471                                               ioff - data_size);
1472                 }
1473
1474                 /* shift the items */
1475                 memmove(leaf->items + slot + 1, leaf->items + slot,
1476                         (nritems - slot) * sizeof(struct btrfs_item));
1477
1478                 /* shift the data */
1479                 memmove(btrfs_leaf_data(leaf) + data_end - data_size,
1480                         btrfs_leaf_data(leaf) +
1481                         data_end, old_data - data_end);
1482                 data_end = old_data;
1483         }
1484         /* setup the item for the new data */
1485         memcpy(&leaf->items[slot].key, &disk_key,
1486                 sizeof(struct btrfs_disk_key));
1487         btrfs_set_item_offset(leaf->items + slot, data_end - data_size);
1488         btrfs_set_item_size(leaf->items + slot, data_size);
1489         btrfs_set_header_nritems(&leaf->header, nritems + 1);
1490
1491         ret = 0;
1492         if (slot == 0)
1493                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
1494
1495         BUG_ON(list_empty(&leaf_buf->dirty));
1496         if (btrfs_leaf_free_space(root, leaf) < 0)
1497                 BUG();
1498         check_leaf(root, path, 0);
1499 out:
1500         return ret;
1501 }
1502
1503 /*
1504  * Given a key and some data, insert an item into the tree.
1505  * This does all the path init required, making room in the tree if needed.
1506  */
1507 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
1508                       *root, struct btrfs_key *cpu_key, void *data, u32
1509                       data_size)
1510 {
1511         int ret = 0;
1512         struct btrfs_path path;
1513         u8 *ptr;
1514
1515         btrfs_init_path(&path);
1516         ret = btrfs_insert_empty_item(trans, root, &path, cpu_key, data_size);
1517         if (!ret) {
1518                 ptr = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0], u8);
1519                 memcpy(ptr, data, data_size);
1520         }
1521         btrfs_release_path(root, &path);
1522         return ret;
1523 }
1524
1525 /*
1526  * delete the pointer from a given node.
1527  *
1528  * If the delete empties a node, the node is removed from the tree,
1529  * continuing all the way the root if required.  The root is converted into
1530  * a leaf if all the nodes are emptied.
1531  */
1532 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1533                    struct btrfs_path *path, int level, int slot)
1534 {
1535         struct btrfs_node *node;
1536         struct btrfs_buffer *parent = path->nodes[level];
1537         u32 nritems;
1538         int ret = 0;
1539         int wret;
1540
1541         node = &parent->node;
1542         nritems = btrfs_header_nritems(&node->header);
1543         if (slot != nritems -1) {
1544                 memmove(node->ptrs + slot, node->ptrs + slot + 1,
1545                         sizeof(struct btrfs_key_ptr) * (nritems - slot - 1));
1546         }
1547         nritems--;
1548         btrfs_set_header_nritems(&node->header, nritems);
1549         if (nritems == 0 && parent == root->node) {
1550                 BUG_ON(btrfs_header_level(&root->node->node.header) != 1);
1551                 /* just turn the root into a leaf and break */
1552                 btrfs_set_header_level(&root->node->node.header, 0);
1553         } else if (slot == 0) {
1554                 wret = fixup_low_keys(trans, root, path, &node->ptrs[0].key,
1555                                       level + 1);
1556                 if (wret)
1557                         ret = wret;
1558         }
1559         BUG_ON(list_empty(&parent->dirty));
1560         return ret;
1561 }
1562
1563 /*
1564  * delete the item at the leaf level in path.  If that empties
1565  * the leaf, remove it from the tree
1566  */
1567 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1568                    struct btrfs_path *path)
1569 {
1570         int slot;
1571         struct btrfs_leaf *leaf;
1572         struct btrfs_buffer *leaf_buf;
1573         int doff;
1574         int dsize;
1575         int ret = 0;
1576         int wret;
1577         u32 nritems;
1578
1579         leaf_buf = path->nodes[0];
1580         leaf = &leaf_buf->leaf;
1581         slot = path->slots[0];
1582         doff = btrfs_item_offset(leaf->items + slot);
1583         dsize = btrfs_item_size(leaf->items + slot);
1584         nritems = btrfs_header_nritems(&leaf->header);
1585
1586         if (slot != nritems - 1) {
1587                 int i;
1588                 int data_end = leaf_data_end(root, leaf);
1589                 memmove(btrfs_leaf_data(leaf) + data_end + dsize,
1590                         btrfs_leaf_data(leaf) + data_end,
1591                         doff - data_end);
1592                 for (i = slot + 1; i < nritems; i++) {
1593                         u32 ioff = btrfs_item_offset(leaf->items + i);
1594                         btrfs_set_item_offset(leaf->items + i, ioff + dsize);
1595                 }
1596                 memmove(leaf->items + slot, leaf->items + slot + 1,
1597                         sizeof(struct btrfs_item) *
1598                         (nritems - slot - 1));
1599         }
1600         btrfs_set_header_nritems(&leaf->header, nritems - 1);
1601         nritems--;
1602         /* delete the leaf if we've emptied it */
1603         if (nritems == 0) {
1604                 if (leaf_buf == root->node) {
1605                         btrfs_set_header_level(&leaf->header, 0);
1606                         BUG_ON(list_empty(&leaf_buf->dirty));
1607                 } else {
1608                         u64 generation =
1609                           btrfs_header_generation(&path->nodes[1]->node.header);
1610
1611                         clean_tree_block(trans, root, leaf_buf);
1612                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
1613                         if (wret)
1614                                 ret = wret;
1615                         wret = btrfs_free_extent(trans, root, leaf_buf->bytenr,
1616                                                  leaf_buf->size,
1617                                                  root->root_key.objectid,
1618                                                  generation, 0, 0, 1);
1619                         if (wret)
1620                                 ret = wret;
1621                 }
1622         } else {
1623                 int used = leaf_space_used(leaf, 0, nritems);
1624                 if (slot == 0) {
1625                         wret = fixup_low_keys(trans, root, path,
1626                                               &leaf->items[0].key, 1);
1627                         if (wret)
1628                                 ret = wret;
1629                 }
1630                 BUG_ON(list_empty(&leaf_buf->dirty));
1631
1632                 /* delete the leaf if it is mostly empty */
1633                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
1634                         /* push_leaf_left fixes the path.
1635                          * make sure the path still points to our leaf
1636                          * for possible call to del_ptr below
1637                          */
1638                         slot = path->slots[1];
1639                         leaf_buf->count++;
1640                         wret = push_leaf_right(trans, root, path, 1, 1);
1641                         if (wret < 0)
1642                                 ret = wret;
1643                         if (path->nodes[0] == leaf_buf &&
1644                             btrfs_header_nritems(&leaf->header)) {
1645                                 wret = push_leaf_left(trans, root, path, 1, 1);
1646                                 if (wret < 0)
1647                                         ret = wret;
1648                         }
1649                         if (btrfs_header_nritems(&leaf->header) == 0) {
1650                                 u64 bytenr = leaf_buf->bytenr;
1651                                 struct btrfs_buffer *parent = path->nodes[1];
1652                                 u64 generation =
1653                                   btrfs_header_generation(&parent->node.header);
1654
1655                                 clean_tree_block(trans, root, leaf_buf);
1656                                 wret = del_ptr(trans, root, path, 1, slot);
1657                                 if (wret)
1658                                         ret = wret;
1659                                 wret = btrfs_free_extent(trans, root, bytenr,
1660                                                  leaf_buf->size,
1661                                                  root->root_key.objectid,
1662                                                  generation, 0, 0, 1);
1663                                 btrfs_block_release(root, leaf_buf);
1664                                 if (wret)
1665                                         ret = wret;
1666                         } else {
1667                                 btrfs_block_release(root, leaf_buf);
1668                         }
1669                 }
1670         }
1671         return ret;
1672 }
1673 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
1674                         struct btrfs_root *root,
1675                         struct btrfs_path *path,
1676                         u32 new_size, int from_end)
1677 {
1678         int ret = 0;
1679         int slot;
1680         int slot_orig;
1681         struct btrfs_leaf *leaf;
1682         struct btrfs_item *item;
1683         u32 nritems;
1684         unsigned int data_end;
1685         unsigned int old_data_start;
1686         unsigned int old_size;
1687         unsigned int size_diff;
1688         int i;
1689
1690         slot_orig = path->slots[0];
1691         leaf = &path->nodes[0]->leaf;
1692         slot = path->slots[0];
1693
1694         old_size = btrfs_item_size(leaf->items + slot);
1695         if (old_size == new_size)
1696                 return 0;
1697
1698         nritems = btrfs_header_nritems(&leaf->header);
1699         data_end = leaf_data_end(root, leaf);
1700
1701         old_data_start = btrfs_item_offset(leaf->items + slot);
1702
1703         size_diff = old_size - new_size;
1704
1705         BUG_ON(slot < 0);
1706         BUG_ON(slot >= nritems);
1707
1708         /*
1709          * item0..itemN ... dataN.offset..dataN.size .. data0.size
1710          */
1711         /* first correct the data pointers */
1712         for (i = slot; i < nritems; i++) {
1713                 u32 ioff;
1714                 item = leaf->items + i;
1715                 ioff = btrfs_item_offset(item);
1716                 btrfs_set_item_offset(item, ioff + size_diff);
1717         }
1718
1719         /* shift the data */
1720         if (from_end) {
1721                 memmove(btrfs_leaf_data(leaf) + data_end + size_diff,
1722                         btrfs_leaf_data(leaf) + data_end,
1723                         old_data_start + new_size - data_end);
1724         } else {
1725                 struct btrfs_disk_key *disk_key;
1726                 u64 offset;
1727
1728                 disk_key = &leaf->items[slot].key;
1729                 if (btrfs_disk_key_type(disk_key) == BTRFS_EXTENT_DATA_KEY) {
1730                         char *ptr;
1731                         struct btrfs_file_extent_item *fi;
1732
1733                         fi = btrfs_item_ptr(leaf, slot,
1734                                             struct btrfs_file_extent_item);
1735                         fi = (struct btrfs_file_extent_item *)(
1736                              (unsigned long)fi - size_diff);
1737
1738                         if (btrfs_file_extent_type(fi) ==
1739                             BTRFS_FILE_EXTENT_INLINE) {
1740                                 ptr = btrfs_item_ptr(leaf, slot, char);
1741                                 memmove(ptr, (char *)fi,
1742                                         offsetof(struct btrfs_file_extent_item,
1743                                                  disk_bytenr));
1744                         }
1745                 }
1746
1747                 memmove(btrfs_leaf_data(leaf) + data_end + size_diff,
1748                         btrfs_leaf_data(leaf) + data_end,
1749                         old_data_start - data_end);
1750
1751                 offset = btrfs_disk_key_offset(disk_key);
1752                 btrfs_set_disk_key_offset(disk_key, offset + size_diff);
1753                 if (slot == 0)
1754                         fixup_low_keys(trans, root, path, disk_key, 1);
1755         }
1756
1757         item = leaf->items + slot;
1758         btrfs_set_item_size(item, new_size);
1759         BUG_ON(list_empty(&path->nodes[0]->dirty));
1760
1761         ret = 0;
1762         if (btrfs_leaf_free_space(root, leaf) < 0) {
1763                 btrfs_print_leaf(root, leaf);
1764                 BUG();
1765         }
1766         return ret;
1767 }
1768
1769 int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root
1770                       *root, struct btrfs_path *path, u32 data_size)
1771 {
1772         int ret = 0;
1773         int slot;
1774         int slot_orig;
1775         struct btrfs_leaf *leaf;
1776         struct btrfs_buffer *leaf_buf;
1777         u32 nritems;
1778         unsigned int data_end;
1779         unsigned int old_data;
1780         unsigned int old_size;
1781         int i;
1782
1783         slot_orig = path->slots[0];
1784         leaf_buf = path->nodes[0];
1785         leaf = &leaf_buf->leaf;
1786
1787         nritems = btrfs_header_nritems(&leaf->header);
1788         data_end = leaf_data_end(root, leaf);
1789
1790         if (btrfs_leaf_free_space(root, leaf) < data_size)
1791                 BUG();
1792         slot = path->slots[0];
1793         old_data = btrfs_item_end(leaf->items + slot);
1794
1795         BUG_ON(slot < 0);
1796         BUG_ON(slot >= nritems);
1797
1798         /*
1799          * item0..itemN ... dataN.offset..dataN.size .. data0.size
1800          */
1801         /* first correct the data pointers */
1802         for (i = slot; i < nritems; i++) {
1803                 u32 ioff = btrfs_item_offset(leaf->items + i);
1804                 btrfs_set_item_offset(leaf->items + i,
1805                                       ioff - data_size);
1806         }
1807         /* shift the data */
1808         memmove(btrfs_leaf_data(leaf) + data_end - data_size,
1809                 btrfs_leaf_data(leaf) + data_end, old_data - data_end);
1810         data_end = old_data;
1811         old_size = btrfs_item_size(leaf->items + slot);
1812         btrfs_set_item_size(leaf->items + slot, old_size + data_size);
1813
1814         ret = 0;
1815         if (btrfs_leaf_free_space(root, leaf) < 0)
1816                 BUG();
1817         check_leaf(root, path, 0);
1818         return ret;
1819 }
1820
1821 /*
1822  * walk up the tree as far as required to find the next leaf.
1823  * returns 0 if it found something or 1 if there are no greater leaves.
1824  * returns < 0 on io errors.
1825  */
1826 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
1827 {
1828         int slot;
1829         int level = 1;
1830         u64 bytenr;
1831         struct btrfs_buffer *c;
1832         struct btrfs_buffer *next = NULL;
1833
1834         while(level < BTRFS_MAX_LEVEL) {
1835                 if (!path->nodes[level])
1836                         return 1;
1837                 slot = path->slots[level] + 1;
1838                 c = path->nodes[level];
1839                 if (slot >= btrfs_header_nritems(&c->node.header)) {
1840                         level++;
1841                         continue;
1842                 }
1843                 bytenr = btrfs_node_blockptr(&c->node, slot);
1844                 if (next)
1845                         btrfs_block_release(root, next);
1846                 next = read_tree_block(root, bytenr,
1847                                        btrfs_level_size(root, level - 1));
1848                 break;
1849         }
1850         path->slots[level] = slot;
1851         while(1) {
1852                 level--;
1853                 c = path->nodes[level];
1854                 btrfs_block_release(root, c);
1855                 path->nodes[level] = next;
1856                 path->slots[level] = 0;
1857                 if (!level)
1858                         break;
1859                 next = read_tree_block(root,
1860                                        btrfs_node_blockptr(&next->node, 0),
1861                                        btrfs_level_size(root, level - 1));
1862         }
1863         check_leaf(root, path, 0);
1864         return 0;
1865 }