fs/btrfs/ctree.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include "ctree.h"
  20 #include "disk-io.h"
  21 #include "transaction.h"
  22
  23 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  24                       *root, struct btrfs_path *path, int level);
  25 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  26                       *root, struct btrfs_key *ins_key,
  27                       struct btrfs_path *path, int data_size);
  28 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
  29                           *root, struct buffer_head *dst, struct buffer_head
  30                           *src);
  31 static int balance_node_right(struct btrfs_trans_handle *trans, struct
  32                               btrfs_root *root, struct buffer_head *dst_buf,
  33                               struct buffer_head *src_buf);
  34 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  35                    struct btrfs_path *path, int level, int slot);
  36
  37 inline void btrfs_init_path(struct btrfs_path *p)
  38 {
  39         memset(p, 0, sizeof(*p));
  40 }
  41
  42 struct btrfs_path *btrfs_alloc_path(void)
  43 {
  44         struct btrfs_path *path;
  45         path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
  46         if (path)
  47                 btrfs_init_path(path);
  48         return path;
  49 }
  50
  51 void btrfs_free_path(struct btrfs_path *p)
  52 {
  53         btrfs_release_path(NULL, p);
  54         kmem_cache_free(btrfs_path_cachep, p);
  55 }
  56
  57 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
  58 {
  59         int i;
  60         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  61                 if (!p->nodes[i])
  62                         break;
  63                 btrfs_block_release(root, p->nodes[i]);
  64         }
  65         memset(p, 0, sizeof(*p));
  66 }
  67
  68 static int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
  69                            *root, struct buffer_head *buf, struct buffer_head
  70                            *parent, int parent_slot, struct buffer_head
  71                            **cow_ret)
  72 {
  73         struct buffer_head *cow;
  74         struct btrfs_node *cow_node;
  75         int ret;
  76
  77         WARN_ON(!buffer_uptodate(buf));
  78         if (trans->transaction != root->fs_info->running_transaction) {
  79                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
  80                        root->fs_info->running_transaction->transid);
  81                 WARN_ON(1);
  82         }
  83         if (trans->transid != root->fs_info->generation) {
  84                 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
  85                        root->fs_info->generation);
  86                 WARN_ON(1);
  87         }
  88         if (btrfs_header_generation(btrfs_buffer_header(buf)) ==
  89                                     trans->transid) {
  90                 *cow_ret = buf;
  91                 return 0;
  92         }
  93         cow = btrfs_alloc_free_block(trans, root, buf->b_blocknr);
  94         if (IS_ERR(cow))
  95                 return PTR_ERR(cow);
  96         cow_node = btrfs_buffer_node(cow);
  97         if (buf->b_size != root->blocksize || cow->b_size != root->blocksize)
  98                 WARN_ON(1);
  99         memcpy(cow_node, btrfs_buffer_node(buf), root->blocksize);
 100         btrfs_set_header_blocknr(&cow_node->header, bh_blocknr(cow));
 101         btrfs_set_header_generation(&cow_node->header, trans->transid);
 102         btrfs_set_header_owner(&cow_node->header, root->root_key.objectid);
 103         ret = btrfs_inc_ref(trans, root, buf);
 104         if (ret)
 105                 return ret;
 106         if (buf == root->node) {
 107                 root->node = cow;
 108                 get_bh(cow);
 109                 if (buf != root->commit_root) {
 110                         btrfs_free_extent(trans, root, bh_blocknr(buf), 1, 1);
 111                 }
 112                 btrfs_block_release(root, buf);
 113         } else {
 114                 btrfs_set_node_blockptr(btrfs_buffer_node(parent), parent_slot,
 115                                         bh_blocknr(cow));
 116                 btrfs_mark_buffer_dirty(parent);
 117                 btrfs_free_extent(trans, root, bh_blocknr(buf), 1, 1);
 118         }
 119         btrfs_block_release(root, buf);
 120         btrfs_mark_buffer_dirty(cow);
 121         *cow_ret = cow;
 122         return 0;
 123 }
 124
 125 /*
 126  * The leaf data grows from end-to-front in the node.
 127  * this returns the address of the start of the last item,
 128  * which is the stop of the leaf data stack
 129  */
 130 static inline unsigned int leaf_data_end(struct btrfs_root *root,
 131                                          struct btrfs_leaf *leaf)
 132 {
 133         u32 nr = btrfs_header_nritems(&leaf->header);
 134         if (nr == 0)
 135                 return BTRFS_LEAF_DATA_SIZE(root);
 136         return btrfs_item_offset(leaf->items + nr - 1);
 137 }
 138
 139 /*
 140  * compare two keys in a memcmp fashion
 141  */
 142 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 143 {
 144         struct btrfs_key k1;
 145
 146         btrfs_disk_key_to_cpu(&k1, disk);
 147
 148         if (k1.objectid > k2->objectid)
 149                 return 1;
 150         if (k1.objectid < k2->objectid)
 151                 return -1;
 152         if (k1.flags > k2->flags)
 153                 return 1;
 154         if (k1.flags < k2->flags)
 155                 return -1;
 156         if (k1.offset > k2->offset)
 157                 return 1;
 158         if (k1.offset < k2->offset)
 159                 return -1;
 160         return 0;
 161 }
 162
 163 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
 164                       int level)
 165 {
 166         struct btrfs_node *parent = NULL;
 167         struct btrfs_node *node = btrfs_buffer_node(path->nodes[level]);
 168         int parent_slot;
 169         int slot;
 170         struct btrfs_key cpukey;
 171         u32 nritems = btrfs_header_nritems(&node->header);
 172
 173         if (path->nodes[level + 1])
 174                 parent = btrfs_buffer_node(path->nodes[level + 1]);
 175
 176         slot = path->slots[level];
 177         BUG_ON(nritems == 0);
 178         if (parent) {
 179                 struct btrfs_disk_key *parent_key;
 180
 181                 parent_slot = path->slots[level + 1];
 182                 parent_key = &parent->ptrs[parent_slot].key;
 183                 BUG_ON(memcmp(parent_key, &node->ptrs[0].key,
 184                               sizeof(struct btrfs_disk_key)));
 185                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 186                        btrfs_header_blocknr(&node->header));
 187         }
 188         BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
 189         if (slot != 0) {
 190                 btrfs_disk_key_to_cpu(&cpukey, &node->ptrs[slot - 1].key);
 191                 BUG_ON(comp_keys(&node->ptrs[slot].key, &cpukey) <= 0);
 192         }
 193         if (slot < nritems - 1) {
 194                 btrfs_disk_key_to_cpu(&cpukey, &node->ptrs[slot + 1].key);
 195                 BUG_ON(comp_keys(&node->ptrs[slot].key, &cpukey) >= 0);
 196         }
 197         return 0;
 198 }
 199
 200 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
 201                       int level)
 202 {
 203         struct btrfs_leaf *leaf = btrfs_buffer_leaf(path->nodes[level]);
 204         struct btrfs_node *parent = NULL;
 205         int parent_slot;
 206         int slot = path->slots[0];
 207         struct btrfs_key cpukey;
 208
 209         u32 nritems = btrfs_header_nritems(&leaf->header);
 210
 211         if (path->nodes[level + 1])
 212                 parent = btrfs_buffer_node(path->nodes[level + 1]);
 213
 214         BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
 215
 216         if (nritems == 0)
 217                 return 0;
 218
 219         if (parent) {
 220                 struct btrfs_disk_key *parent_key;
 221
 222                 parent_slot = path->slots[level + 1];
 223                 parent_key = &parent->ptrs[parent_slot].key;
 224                 BUG_ON(memcmp(parent_key, &leaf->items[0].key,
 225                        sizeof(struct btrfs_disk_key)));
 226                 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
 227                        btrfs_header_blocknr(&leaf->header));
 228         }
 229         if (slot != 0) {
 230                 btrfs_disk_key_to_cpu(&cpukey, &leaf->items[slot - 1].key);
 231                 BUG_ON(comp_keys(&leaf->items[slot].key, &cpukey) <= 0);
 232                 BUG_ON(btrfs_item_offset(leaf->items + slot - 1) !=
 233                         btrfs_item_end(leaf->items + slot));
 234         }
 235         if (slot < nritems - 1) {
 236                 btrfs_disk_key_to_cpu(&cpukey, &leaf->items[slot + 1].key);
 237                 BUG_ON(comp_keys(&leaf->items[slot].key, &cpukey) >= 0);
 238                 BUG_ON(btrfs_item_offset(leaf->items + slot) !=
 239                         btrfs_item_end(leaf->items + slot + 1));
 240         }
 241         BUG_ON(btrfs_item_offset(leaf->items) +
 242                btrfs_item_size(leaf->items) != BTRFS_LEAF_DATA_SIZE(root));
 243         return 0;
 244 }
 245
 246 static int check_block(struct btrfs_root *root, struct btrfs_path *path,
 247                         int level)
 248 {
 249         struct btrfs_node *node = btrfs_buffer_node(path->nodes[level]);
 250         if (memcmp(node->header.fsid, root->fs_info->disk_super->fsid,
 251                    sizeof(node->header.fsid)))
 252                 BUG();
 253         if (level == 0)
 254                 return check_leaf(root, path, level);
 255         return check_node(root, path, level);
 256 }
 257
 258 /*
 259  * search for key in the array p.  items p are item_size apart
 260  * and there are 'max' items in p
 261  * the slot in the array is returned via slot, and it points to
 262  * the place where you would insert key if it is not found in
 263  * the array.
 264  *
 265  * slot may point to max if the key is bigger than all of the keys
 266  */
 267 static int generic_bin_search(char *p, int item_size, struct btrfs_key *key,
 268                        int max, int *slot)
 269 {
 270         int low = 0;
 271         int high = max;
 272         int mid;
 273         int ret;
 274         struct btrfs_disk_key *tmp;
 275
 276         while(low < high) {
 277                 mid = (low + high) / 2;
 278                 tmp = (struct btrfs_disk_key *)(p + mid * item_size);
 279                 ret = comp_keys(tmp, key);
 280
 281                 if (ret < 0)
 282                         low = mid + 1;
 283                 else if (ret > 0)
 284                         high = mid;
 285                 else {
 286                         *slot = mid;
 287                         return 0;
 288                 }
 289         }
 290         *slot = low;
 291         return 1;
 292 }
 293
 294 /*
 295  * simple bin_search frontend that does the right thing for
 296  * leaves vs nodes
 297  */
 298 static int bin_search(struct btrfs_node *c, struct btrfs_key *key, int *slot)
 299 {
 300         if (btrfs_is_leaf(c)) {
 301                 struct btrfs_leaf *l = (struct btrfs_leaf *)c;
 302                 return generic_bin_search((void *)l->items,
 303                                           sizeof(struct btrfs_item),
 304                                           key, btrfs_header_nritems(&c->header),
 305                                           slot);
 306         } else {
 307                 return generic_bin_search((void *)c->ptrs,
 308                                           sizeof(struct btrfs_key_ptr),
 309                                           key, btrfs_header_nritems(&c->header),
 310                                           slot);
 311         }
 312         return -1;
 313 }
 314
 315 static struct buffer_head *read_node_slot(struct btrfs_root *root,
 316                                    struct buffer_head *parent_buf,
 317                                    int slot)
 318 {
 319         struct btrfs_node *node = btrfs_buffer_node(parent_buf);
 320         if (slot < 0)
 321                 return NULL;
 322         if (slot >= btrfs_header_nritems(&node->header))
 323                 return NULL;
 324         return read_tree_block(root, btrfs_node_blockptr(node, slot));
 325 }
 326
 327 static int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root
 328                          *root, struct btrfs_path *path, int level)
 329 {
 330         struct buffer_head *right_buf;
 331         struct buffer_head *mid_buf;
 332         struct buffer_head *left_buf;
 333         struct buffer_head *parent_buf = NULL;
 334         struct btrfs_node *right = NULL;
 335         struct btrfs_node *mid;
 336         struct btrfs_node *left = NULL;
 337         struct btrfs_node *parent = NULL;
 338         int ret = 0;
 339         int wret;
 340         int pslot;
 341         int orig_slot = path->slots[level];
 342         int err_on_enospc = 0;
 343         u64 orig_ptr;
 344
 345         if (level == 0)
 346                 return 0;
 347
 348         mid_buf = path->nodes[level];
 349         mid = btrfs_buffer_node(mid_buf);
 350         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 351
 352         if (level < BTRFS_MAX_LEVEL - 1)
 353                 parent_buf = path->nodes[level + 1];
 354         pslot = path->slots[level + 1];
 355
 356         /*
 357          * deal with the case where there is only one pointer in the root
 358          * by promoting the node below to a root
 359          */
 360         if (!parent_buf) {
 361                 struct buffer_head *child;
 362                 u64 blocknr = bh_blocknr(mid_buf);
 363
 364                 if (btrfs_header_nritems(&mid->header) != 1)
 365                         return 0;
 366
 367                 /* promote the child to a root */
 368                 child = read_node_slot(root, mid_buf, 0);
 369                 BUG_ON(!child);
 370                 root->node = child;
 371                 path->nodes[level] = NULL;
 372                 clean_tree_block(trans, root, mid_buf);
 373                 wait_on_buffer(mid_buf);
 374                 /* once for the path */
 375                 btrfs_block_release(root, mid_buf);
 376                 /* once for the root ptr */
 377                 btrfs_block_release(root, mid_buf);
 378                 return btrfs_free_extent(trans, root, blocknr, 1, 1);
 379         }
 380         parent = btrfs_buffer_node(parent_buf);
 381
 382         if (btrfs_header_nritems(&mid->header) >
 383             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
 384                 return 0;
 385
 386         if (btrfs_header_nritems(&mid->header) < 2)
 387                 err_on_enospc = 1;
 388
 389         left_buf = read_node_slot(root, parent_buf, pslot - 1);
 390         right_buf = read_node_slot(root, parent_buf, pslot + 1);
 391
 392         /* first, try to make some room in the middle buffer */
 393         if (left_buf) {
 394                 wret = btrfs_cow_block(trans, root, left_buf,
 395                                        parent_buf, pslot - 1, &left_buf);
 396                 if (wret) {
 397                         ret = wret;
 398                         goto enospc;
 399                 }
 400                 left = btrfs_buffer_node(left_buf);
 401                 orig_slot += btrfs_header_nritems(&left->header);
 402                 wret = push_node_left(trans, root, left_buf, mid_buf);
 403                 if (wret < 0)
 404                         ret = wret;
 405                 if (btrfs_header_nritems(&mid->header) < 2)
 406                         err_on_enospc = 1;
 407         }
 408
 409         /*
 410          * then try to empty the right most buffer into the middle
 411          */
 412         if (right_buf) {
 413                 wret = btrfs_cow_block(trans, root, right_buf,
 414                                        parent_buf, pslot + 1, &right_buf);
 415                 if (wret) {
 416                         ret = wret;
 417                         goto enospc;
 418                 }
 419
 420                 right = btrfs_buffer_node(right_buf);
 421                 wret = push_node_left(trans, root, mid_buf, right_buf);
 422                 if (wret < 0 && wret != -ENOSPC)
 423                         ret = wret;
 424                 if (btrfs_header_nritems(&right->header) == 0) {
 425                         u64 blocknr = bh_blocknr(right_buf);
 426                         clean_tree_block(trans, root, right_buf);
 427                         wait_on_buffer(right_buf);
 428                         btrfs_block_release(root, right_buf);
 429                         right_buf = NULL;
 430                         right = NULL;
 431                         wret = del_ptr(trans, root, path, level + 1, pslot +
 432                                        1);
 433                         if (wret)
 434                                 ret = wret;
 435                         wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
 436                         if (wret)
 437                                 ret = wret;
 438                 } else {
 439                         btrfs_memcpy(root, parent,
 440                                      &parent->ptrs[pslot + 1].key,
 441                                      &right->ptrs[0].key,
 442                                      sizeof(struct btrfs_disk_key));
 443                         btrfs_mark_buffer_dirty(parent_buf);
 444                 }
 445         }
 446         if (btrfs_header_nritems(&mid->header) == 1) {
 447                 /*
 448                  * we're not allowed to leave a node with one item in the
 449                  * tree during a delete.  A deletion from lower in the tree
 450                  * could try to delete the only pointer in this node.
 451                  * So, pull some keys from the left.
 452                  * There has to be a left pointer at this point because
 453                  * otherwise we would have pulled some pointers from the
 454                  * right
 455                  */
 456                 BUG_ON(!left_buf);
 457                 wret = balance_node_right(trans, root, mid_buf, left_buf);
 458                 if (wret < 0) {
 459                         ret = wret;
 460                         goto enospc;
 461                 }
 462                 BUG_ON(wret == 1);
 463         }
 464         if (btrfs_header_nritems(&mid->header) == 0) {
 465                 /* we've managed to empty the middle node, drop it */
 466                 u64 blocknr = bh_blocknr(mid_buf);
 467                 clean_tree_block(trans, root, mid_buf);
 468                 wait_on_buffer(mid_buf);
 469                 btrfs_block_release(root, mid_buf);
 470                 mid_buf = NULL;
 471                 mid = NULL;
 472                 wret = del_ptr(trans, root, path, level + 1, pslot);
 473                 if (wret)
 474                         ret = wret;
 475                 wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
 476                 if (wret)
 477                         ret = wret;
 478         } else {
 479                 /* update the parent key to reflect our changes */
 480                 btrfs_memcpy(root, parent,
 481                              &parent->ptrs[pslot].key, &mid->ptrs[0].key,
 482                              sizeof(struct btrfs_disk_key));
 483                 btrfs_mark_buffer_dirty(parent_buf);
 484         }
 485
 486         /* update the path */
 487         if (left_buf) {
 488                 if (btrfs_header_nritems(&left->header) > orig_slot) {
 489                         get_bh(left_buf);
 490                         path->nodes[level] = left_buf;
 491                         path->slots[level + 1] -= 1;
 492                         path->slots[level] = orig_slot;
 493                         if (mid_buf)
 494                                 btrfs_block_release(root, mid_buf);
 495                 } else {
 496                         orig_slot -= btrfs_header_nritems(&left->header);
 497                         path->slots[level] = orig_slot;
 498                 }
 499         }
 500         /* double check we haven't messed things up */
 501         check_block(root, path, level);
 502         if (orig_ptr !=
 503             btrfs_node_blockptr(btrfs_buffer_node(path->nodes[level]),
 504                                 path->slots[level]))
 505                 BUG();
 506 enospc:
 507         if (right_buf)
 508                 btrfs_block_release(root, right_buf);
 509         if (left_buf)
 510                 btrfs_block_release(root, left_buf);
 511         return ret;
 512 }
 513
 514 /* returns zero if the push worked, non-zero otherwise */
 515 static int push_nodes_for_insert(struct btrfs_trans_handle *trans,
 516                                 struct btrfs_root *root,
 517                                 struct btrfs_path *path, int level)
 518 {
 519         struct buffer_head *right_buf;
 520         struct buffer_head *mid_buf;
 521         struct buffer_head *left_buf;
 522         struct buffer_head *parent_buf = NULL;
 523         struct btrfs_node *right = NULL;
 524         struct btrfs_node *mid;
 525         struct btrfs_node *left = NULL;
 526         struct btrfs_node *parent = NULL;
 527         int ret = 0;
 528         int wret;
 529         int pslot;
 530         int orig_slot = path->slots[level];
 531         u64 orig_ptr;
 532
 533         if (level == 0)
 534                 return 1;
 535
 536         mid_buf = path->nodes[level];
 537         mid = btrfs_buffer_node(mid_buf);
 538         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 539
 540         if (level < BTRFS_MAX_LEVEL - 1)
 541                 parent_buf = path->nodes[level + 1];
 542         pslot = path->slots[level + 1];
 543
 544         if (!parent_buf)
 545                 return 1;
 546         parent = btrfs_buffer_node(parent_buf);
 547
 548         left_buf = read_node_slot(root, parent_buf, pslot - 1);
 549
 550         /* first, try to make some room in the middle buffer */
 551         if (left_buf) {
 552                 u32 left_nr;
 553                 left = btrfs_buffer_node(left_buf);
 554                 left_nr = btrfs_header_nritems(&left->header);
 555                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 556                         wret = 1;
 557                 } else {
 558                         ret = btrfs_cow_block(trans, root, left_buf, parent_buf,
 559                                               pslot - 1, &left_buf);
 560                         if (ret)
 561                                 wret = 1;
 562                         else {
 563                                 left = btrfs_buffer_node(left_buf);
 564                                 wret = push_node_left(trans, root,
 565                                                       left_buf, mid_buf);
 566                         }
 567                 }
 568                 if (wret < 0)
 569                         ret = wret;
 570                 if (wret == 0) {
 571                         orig_slot += left_nr;
 572                         btrfs_memcpy(root, parent,
 573                                      &parent->ptrs[pslot].key,
 574                                      &mid->ptrs[0].key,
 575                                      sizeof(struct btrfs_disk_key));
 576                         btrfs_mark_buffer_dirty(parent_buf);
 577                         if (btrfs_header_nritems(&left->header) > orig_slot) {
 578                                 path->nodes[level] = left_buf;
 579                                 path->slots[level + 1] -= 1;
 580                                 path->slots[level] = orig_slot;
 581                                 btrfs_block_release(root, mid_buf);
 582                         } else {
 583                                 orig_slot -=
 584                                         btrfs_header_nritems(&left->header);
 585                                 path->slots[level] = orig_slot;
 586                                 btrfs_block_release(root, left_buf);
 587                         }
 588                         check_node(root, path, level);
 589                         return 0;
 590                 }
 591                 btrfs_block_release(root, left_buf);
 592         }
 593         right_buf = read_node_slot(root, parent_buf, pslot + 1);
 594
 595         /*
 596          * then try to empty the right most buffer into the middle
 597          */
 598         if (right_buf) {
 599                 u32 right_nr;
 600                 right = btrfs_buffer_node(right_buf);
 601                 right_nr = btrfs_header_nritems(&right->header);
 602                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 603                         wret = 1;
 604                 } else {
 605                         ret = btrfs_cow_block(trans, root, right_buf,
 606                                               parent_buf, pslot + 1,
 607                                               &right_buf);
 608                         if (ret)
 609                                 wret = 1;
 610                         else {
 611                                 right = btrfs_buffer_node(right_buf);
 612                                 wret = balance_node_right(trans, root,
 613                                                           right_buf, mid_buf);
 614                         }
 615                 }
 616                 if (wret < 0)
 617                         ret = wret;
 618                 if (wret == 0) {
 619                         btrfs_memcpy(root, parent,
 620                                      &parent->ptrs[pslot + 1].key,
 621                                      &right->ptrs[0].key,
 622                                      sizeof(struct btrfs_disk_key));
 623                         btrfs_mark_buffer_dirty(parent_buf);
 624                         if (btrfs_header_nritems(&mid->header) <= orig_slot) {
 625                                 path->nodes[level] = right_buf;
 626                                 path->slots[level + 1] += 1;
 627                                 path->slots[level] = orig_slot -
 628                                         btrfs_header_nritems(&mid->header);
 629                                 btrfs_block_release(root, mid_buf);
 630                         } else {
 631                                 btrfs_block_release(root, right_buf);
 632                         }
 633                         check_node(root, path, level);
 634                         return 0;
 635                 }
 636                 btrfs_block_release(root, right_buf);
 637         }
 638         check_node(root, path, level);
 639         return 1;
 640 }
 641
 642 /*
 643  * look for key in the tree.  path is filled in with nodes along the way
 644  * if key is found, we return zero and you can find the item in the leaf
 645  * level of the path (level 0)
 646  *
 647  * If the key isn't found, the path points to the slot where it should
 648  * be inserted, and 1 is returned.  If there are other errors during the
 649  * search a negative error number is returned.
 650  *
 651  * if ins_len > 0, nodes and leaves will be split as we walk down the
 652  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
 653  * possible)
 654  */
 655 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 656                       *root, struct btrfs_key *key, struct btrfs_path *p, int
 657                       ins_len, int cow)
 658 {
 659         struct buffer_head *b;
 660         struct buffer_head *cow_buf;
 661         struct btrfs_node *c;
 662         int slot;
 663         int ret;
 664         int level;
 665
 666         WARN_ON(p->nodes[0] != NULL);
 667         WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
 668 again:
 669         b = root->node;
 670         get_bh(b);
 671         while (b) {
 672                 c = btrfs_buffer_node(b);
 673                 level = btrfs_header_level(&c->header);
 674                 if (cow) {
 675                         int wret;
 676                         wret = btrfs_cow_block(trans, root, b,
 677                                                p->nodes[level + 1],
 678                                                p->slots[level + 1],
 679                                                &cow_buf);
 680                         if (wret) {
 681                                 btrfs_block_release(root, cow_buf);
 682                                 return wret;
 683                         }
 684                         b = cow_buf;
 685                         c = btrfs_buffer_node(b);
 686                 }
 687                 BUG_ON(!cow && ins_len);
 688                 if (level != btrfs_header_level(&c->header))
 689                         WARN_ON(1);
 690                 level = btrfs_header_level(&c->header);
 691                 p->nodes[level] = b;
 692                 ret = check_block(root, p, level);
 693                 if (ret)
 694                         return -1;
 695                 ret = bin_search(c, key, &slot);
 696                 if (!btrfs_is_leaf(c)) {
 697                         if (ret && slot > 0)
 698                                 slot -= 1;
 699                         p->slots[level] = slot;
 700                         if (ins_len > 0 && btrfs_header_nritems(&c->header) >=
 701                             BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
 702                                 int sret = split_node(trans, root, p, level);
 703                                 BUG_ON(sret > 0);
 704                                 if (sret)
 705                                         return sret;
 706                                 b = p->nodes[level];
 707                                 c = btrfs_buffer_node(b);
 708                                 slot = p->slots[level];
 709                         } else if (ins_len < 0) {
 710                                 int sret = balance_level(trans, root, p,
 711                                                          level);
 712                                 if (sret)
 713                                         return sret;
 714                                 b = p->nodes[level];
 715                                 if (!b)
 716                                         goto again;
 717                                 c = btrfs_buffer_node(b);
 718                                 slot = p->slots[level];
 719                                 BUG_ON(btrfs_header_nritems(&c->header) == 1);
 720                         }
 721                         b = read_tree_block(root, btrfs_node_blockptr(c, slot));
 722                 } else {
 723                         struct btrfs_leaf *l = (struct btrfs_leaf *)c;
 724                         p->slots[level] = slot;
 725                         if (ins_len > 0 && btrfs_leaf_free_space(root, l) <
 726                             sizeof(struct btrfs_item) + ins_len) {
 727                                 int sret = split_leaf(trans, root, key,
 728                                                       p, ins_len);
 729                                 BUG_ON(sret > 0);
 730                                 if (sret)
 731                                         return sret;
 732                         }
 733                         return ret;
 734                 }
 735         }
 736         return 1;
 737 }
 738
 739 /*
 740  * adjust the pointers going up the tree, starting at level
 741  * making sure the right key of each node is points to 'key'.
 742  * This is used after shifting pointers to the left, so it stops
 743  * fixing up pointers when a given leaf/node is not in slot 0 of the
 744  * higher levels
 745  *
 746  * If this fails to write a tree block, it returns -1, but continues
 747  * fixing up the blocks in ram so the tree is consistent.
 748  */
 749 static int fixup_low_keys(struct btrfs_trans_handle *trans, struct btrfs_root
 750                           *root, struct btrfs_path *path, struct btrfs_disk_key
 751                           *key, int level)
 752 {
 753         int i;
 754         int ret = 0;
 755         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
 756                 struct btrfs_node *t;
 757                 int tslot = path->slots[i];
 758                 if (!path->nodes[i])
 759                         break;
 760                 t = btrfs_buffer_node(path->nodes[i]);
 761                 btrfs_memcpy(root, t, &t->ptrs[tslot].key, key, sizeof(*key));
 762                 btrfs_mark_buffer_dirty(path->nodes[i]);
 763                 if (tslot != 0)
 764                         break;
 765         }
 766         return ret;
 767 }
 768
 769 /*
 770  * try to push data from one node into the next node left in the
 771  * tree.
 772  *
 773  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
 774  * error, and > 0 if there was no room in the left hand block.
 775  */
 776 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
 777                           *root, struct buffer_head *dst_buf, struct
 778                           buffer_head *src_buf)
 779 {
 780         struct btrfs_node *src = btrfs_buffer_node(src_buf);
 781         struct btrfs_node *dst = btrfs_buffer_node(dst_buf);
 782         int push_items = 0;
 783         int src_nritems;
 784         int dst_nritems;
 785         int ret = 0;
 786
 787         src_nritems = btrfs_header_nritems(&src->header);
 788         dst_nritems = btrfs_header_nritems(&dst->header);
 789         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
 790
 791         if (push_items <= 0) {
 792                 return 1;
 793         }
 794
 795         if (src_nritems < push_items)
 796                 push_items = src_nritems;
 797
 798         btrfs_memcpy(root, dst, dst->ptrs + dst_nritems, src->ptrs,
 799                      push_items * sizeof(struct btrfs_key_ptr));
 800         if (push_items < src_nritems) {
 801                 btrfs_memmove(root, src, src->ptrs, src->ptrs + push_items,
 802                         (src_nritems - push_items) *
 803                         sizeof(struct btrfs_key_ptr));
 804         }
 805         btrfs_set_header_nritems(&src->header, src_nritems - push_items);
 806         btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
 807         btrfs_mark_buffer_dirty(src_buf);
 808         btrfs_mark_buffer_dirty(dst_buf);
 809         return ret;
 810 }
 811
 812 /*
 813  * try to push data from one node into the next node right in the
 814  * tree.
 815  *
 816  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
 817  * error, and > 0 if there was no room in the right hand block.
 818  *
 819  * this will  only push up to 1/2 the contents of the left node over
 820  */
 821 static int balance_node_right(struct btrfs_trans_handle *trans, struct
 822                               btrfs_root *root, struct buffer_head *dst_buf,
 823                               struct buffer_head *src_buf)
 824 {
 825         struct btrfs_node *src = btrfs_buffer_node(src_buf);
 826         struct btrfs_node *dst = btrfs_buffer_node(dst_buf);
 827         int push_items = 0;
 828         int max_push;
 829         int src_nritems;
 830         int dst_nritems;
 831         int ret = 0;
 832
 833         src_nritems = btrfs_header_nritems(&src->header);
 834         dst_nritems = btrfs_header_nritems(&dst->header);
 835         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
 836         if (push_items <= 0) {
 837                 return 1;
 838         }
 839
 840         max_push = src_nritems / 2 + 1;
 841         /* don't try to empty the node */
 842         if (max_push > src_nritems)
 843                 return 1;
 844         if (max_push < push_items)
 845                 push_items = max_push;
 846
 847         btrfs_memmove(root, dst, dst->ptrs + push_items, dst->ptrs,
 848                       dst_nritems * sizeof(struct btrfs_key_ptr));
 849
 850         btrfs_memcpy(root, dst, dst->ptrs,
 851                      src->ptrs + src_nritems - push_items,
 852                      push_items * sizeof(struct btrfs_key_ptr));
 853
 854         btrfs_set_header_nritems(&src->header, src_nritems - push_items);
 855         btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
 856
 857         btrfs_mark_buffer_dirty(src_buf);
 858         btrfs_mark_buffer_dirty(dst_buf);
 859         return ret;
 860 }
 861
 862 /*
 863  * helper function to insert a new root level in the tree.
 864  * A new node is allocated, and a single item is inserted to
 865  * point to the existing root
 866  *
 867  * returns zero on success or < 0 on failure.
 868  */
 869 static int insert_new_root(struct btrfs_trans_handle *trans, struct btrfs_root
 870                            *root, struct btrfs_path *path, int level)
 871 {
 872         struct buffer_head *t;
 873         struct btrfs_node *lower;
 874         struct btrfs_node *c;
 875         struct btrfs_disk_key *lower_key;
 876
 877         BUG_ON(path->nodes[level]);
 878         BUG_ON(path->nodes[level-1] != root->node);
 879
 880         t = btrfs_alloc_free_block(trans, root, root->node->b_blocknr);
 881         if (IS_ERR(t))
 882                 return PTR_ERR(t);
 883         c = btrfs_buffer_node(t);
 884         memset(c, 0, root->blocksize);
 885         btrfs_set_header_nritems(&c->header, 1);
 886         btrfs_set_header_level(&c->header, level);
 887         btrfs_set_header_blocknr(&c->header, bh_blocknr(t));
 888         btrfs_set_header_generation(&c->header, trans->transid);
 889         btrfs_set_header_owner(&c->header, root->root_key.objectid);
 890         lower = btrfs_buffer_node(path->nodes[level-1]);
 891         memcpy(c->header.fsid, root->fs_info->disk_super->fsid,
 892                sizeof(c->header.fsid));
 893         if (btrfs_is_leaf(lower))
 894                 lower_key = &((struct btrfs_leaf *)lower)->items[0].key;
 895         else
 896                 lower_key = &lower->ptrs[0].key;
 897         btrfs_memcpy(root, c, &c->ptrs[0].key, lower_key,
 898                      sizeof(struct btrfs_disk_key));
 899         btrfs_set_node_blockptr(c, 0, bh_blocknr(path->nodes[level - 1]));
 900
 901         btrfs_mark_buffer_dirty(t);
 902
 903         /* the super has an extra ref to root->node */
 904         btrfs_block_release(root, root->node);
 905         root->node = t;
 906         get_bh(t);
 907         path->nodes[level] = t;
 908         path->slots[level] = 0;
 909         return 0;
 910 }
 911
 912 /*
 913  * worker function to insert a single pointer in a node.
 914  * the node should have enough room for the pointer already
 915  *
 916  * slot and level indicate where you want the key to go, and
 917  * blocknr is the block the key points to.
 918  *
 919  * returns zero on success and < 0 on any error
 920  */
 921 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
 922                       *root, struct btrfs_path *path, struct btrfs_disk_key
 923                       *key, u64 blocknr, int slot, int level)
 924 {
 925         struct btrfs_node *lower;
 926         int nritems;
 927
 928         BUG_ON(!path->nodes[level]);
 929         lower = btrfs_buffer_node(path->nodes[level]);
 930         nritems = btrfs_header_nritems(&lower->header);
 931         if (slot > nritems)
 932                 BUG();
 933         if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
 934                 BUG();
 935         if (slot != nritems) {
 936                 btrfs_memmove(root, lower, lower->ptrs + slot + 1,
 937                               lower->ptrs + slot,
 938                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
 939         }
 940         btrfs_memcpy(root, lower, &lower->ptrs[slot].key,
 941                      key, sizeof(struct btrfs_disk_key));
 942         btrfs_set_node_blockptr(lower, slot, blocknr);
 943         btrfs_set_header_nritems(&lower->header, nritems + 1);
 944         btrfs_mark_buffer_dirty(path->nodes[level]);
 945         check_node(root, path, level);
 946         return 0;
 947 }
 948
 949 /*
 950  * split the node at the specified level in path in two.
 951  * The path is corrected to point to the appropriate node after the split
 952  *
 953  * Before splitting this tries to make some room in the node by pushing
 954  * left and right, if either one works, it returns right away.
 955  *
 956  * returns 0 on success and < 0 on failure
 957  */
 958 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
 959                       *root, struct btrfs_path *path, int level)
 960 {
 961         struct buffer_head *t;
 962         struct btrfs_node *c;
 963         struct buffer_head *split_buffer;
 964         struct btrfs_node *split;
 965         int mid;
 966         int ret;
 967         int wret;
 968         u32 c_nritems;
 969
 970         t = path->nodes[level];
 971         c = btrfs_buffer_node(t);
 972         if (t == root->node) {
 973                 /* trying to split the root, lets make a new one */
 974                 ret = insert_new_root(trans, root, path, level + 1);
 975                 if (ret)
 976                         return ret;
 977         } else {
 978                 ret = push_nodes_for_insert(trans, root, path, level);
 979                 t = path->nodes[level];
 980                 c = btrfs_buffer_node(t);
 981                 if (!ret &&
 982                     btrfs_header_nritems(&c->header) <
 983                     BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
 984                         return 0;
 985                 if (ret < 0)
 986                         return ret;
 987         }
 988
 989         c_nritems = btrfs_header_nritems(&c->header);
 990         split_buffer = btrfs_alloc_free_block(trans, root, t->b_blocknr);
 991         if (IS_ERR(split_buffer))
 992                 return PTR_ERR(split_buffer);
 993
 994         split = btrfs_buffer_node(split_buffer);
 995         btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
 996         btrfs_set_header_level(&split->header, btrfs_header_level(&c->header));
 997         btrfs_set_header_blocknr(&split->header, bh_blocknr(split_buffer));
 998         btrfs_set_header_generation(&split->header, trans->transid);
 999         btrfs_set_header_owner(&split->header, root->root_key.objectid);
1000         memcpy(split->header.fsid, root->fs_info->disk_super->fsid,
1001                sizeof(split->header.fsid));
1002         mid = (c_nritems + 1) / 2;
1003         btrfs_memcpy(root, split, split->ptrs, c->ptrs + mid,
1004                      (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1005         btrfs_set_header_nritems(&split->header, c_nritems - mid);
1006         btrfs_set_header_nritems(&c->header, mid);
1007         ret = 0;
1008
1009         btrfs_mark_buffer_dirty(t);
1010         btrfs_mark_buffer_dirty(split_buffer);
1011         wret = insert_ptr(trans, root, path, &split->ptrs[0].key,
1012                           bh_blocknr(split_buffer), path->slots[level + 1] + 1,
1013                           level + 1);
1014         if (wret)
1015                 ret = wret;
1016
1017         if (path->slots[level] >= mid) {
1018                 path->slots[level] -= mid;
1019                 btrfs_block_release(root, t);
1020                 path->nodes[level] = split_buffer;
1021                 path->slots[level + 1] += 1;
1022         } else {
1023                 btrfs_block_release(root, split_buffer);
1024         }
1025         return ret;
1026 }
1027
1028 /*
1029  * how many bytes are required to store the items in a leaf.  start
1030  * and nr indicate which items in the leaf to check.  This totals up the
1031  * space used both by the item structs and the item data
1032  */
1033 static int leaf_space_used(struct btrfs_leaf *l, int start, int nr)
1034 {
1035         int data_len;
1036         int nritems = btrfs_header_nritems(&l->header);
1037         int end = min(nritems, start + nr) - 1;
1038
1039         if (!nr)
1040                 return 0;
1041         data_len = btrfs_item_end(l->items + start);
1042         data_len = data_len - btrfs_item_offset(l->items + end);
1043         data_len += sizeof(struct btrfs_item) * nr;
1044         WARN_ON(data_len < 0);
1045         return data_len;
1046 }
1047
1048 /*
1049  * The space between the end of the leaf items and
1050  * the start of the leaf data.  IOW, how much room
1051  * the leaf has left for both items and data
1052  */
1053 int btrfs_leaf_free_space(struct btrfs_root *root, struct btrfs_leaf *leaf)
1054 {
1055         int nritems = btrfs_header_nritems(&leaf->header);
1056         return BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1057 }
1058
1059 /*
1060  * push some data in the path leaf to the right, trying to free up at
1061  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1062  *
1063  * returns 1 if the push failed because the other node didn't have enough
1064  * room, 0 if everything worked out and < 0 if there were major errors.
1065  */
1066 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1067                            *root, struct btrfs_path *path, int data_size)
1068 {
1069         struct buffer_head *left_buf = path->nodes[0];
1070         struct btrfs_leaf *left = btrfs_buffer_leaf(left_buf);
1071         struct btrfs_leaf *right;
1072         struct buffer_head *right_buf;
1073         struct buffer_head *upper;
1074         struct btrfs_node *upper_node;
1075         int slot;
1076         int i;
1077         int free_space;
1078         int push_space = 0;
1079         int push_items = 0;
1080         struct btrfs_item *item;
1081         u32 left_nritems;
1082         u32 right_nritems;
1083         int ret;
1084
1085         slot = path->slots[1];
1086         if (!path->nodes[1]) {
1087                 return 1;
1088         }
1089         upper = path->nodes[1];
1090         upper_node = btrfs_buffer_node(upper);
1091         if (slot >= btrfs_header_nritems(&upper_node->header) - 1) {
1092                 return 1;
1093         }
1094         right_buf = read_tree_block(root,
1095                     btrfs_node_blockptr(btrfs_buffer_node(upper), slot + 1));
1096         right = btrfs_buffer_leaf(right_buf);
1097         free_space = btrfs_leaf_free_space(root, right);
1098         if (free_space < data_size + sizeof(struct btrfs_item)) {
1099                 btrfs_block_release(root, right_buf);
1100                 return 1;
1101         }
1102         /* cow and double check */
1103         ret = btrfs_cow_block(trans, root, right_buf, upper,
1104                               slot + 1, &right_buf);
1105         if (ret) {
1106                 btrfs_block_release(root, right_buf);
1107                 return 1;
1108         }
1109         right = btrfs_buffer_leaf(right_buf);
1110         free_space = btrfs_leaf_free_space(root, right);
1111         if (free_space < data_size + sizeof(struct btrfs_item)) {
1112                 btrfs_block_release(root, right_buf);
1113                 return 1;
1114         }
1115
1116         left_nritems = btrfs_header_nritems(&left->header);
1117         if (left_nritems == 0) {
1118                 btrfs_block_release(root, right_buf);
1119                 return 1;
1120         }
1121         for (i = left_nritems - 1; i >= 1; i--) {
1122                 item = left->items + i;
1123                 if (path->slots[0] == i)
1124                         push_space += data_size + sizeof(*item);
1125                 if (btrfs_item_size(item) + sizeof(*item) + push_space >
1126                     free_space)
1127                         break;
1128                 push_items++;
1129                 push_space += btrfs_item_size(item) + sizeof(*item);
1130         }
1131         if (push_items == 0) {
1132                 btrfs_block_release(root, right_buf);
1133                 return 1;
1134         }
1135         if (push_items == left_nritems)
1136                 WARN_ON(1);
1137         right_nritems = btrfs_header_nritems(&right->header);
1138         /* push left to right */
1139         push_space = btrfs_item_end(left->items + left_nritems - push_items);
1140         push_space -= leaf_data_end(root, left);
1141         /* make room in the right data area */
1142         btrfs_memmove(root, right, btrfs_leaf_data(right) +
1143                       leaf_data_end(root, right) - push_space,
1144                       btrfs_leaf_data(right) +
1145                       leaf_data_end(root, right), BTRFS_LEAF_DATA_SIZE(root) -
1146                       leaf_data_end(root, right));
1147         /* copy from the left data area */
1148         btrfs_memcpy(root, right, btrfs_leaf_data(right) +
1149                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
1150                      btrfs_leaf_data(left) + leaf_data_end(root, left),
1151                      push_space);
1152         btrfs_memmove(root, right, right->items + push_items, right->items,
1153                 right_nritems * sizeof(struct btrfs_item));
1154         /* copy the items from left to right */
1155         btrfs_memcpy(root, right, right->items, left->items +
1156                      left_nritems - push_items,
1157                      push_items * sizeof(struct btrfs_item));
1158
1159         /* update the item pointers */
1160         right_nritems += push_items;
1161         btrfs_set_header_nritems(&right->header, right_nritems);
1162         push_space = BTRFS_LEAF_DATA_SIZE(root);
1163         for (i = 0; i < right_nritems; i++) {
1164                 btrfs_set_item_offset(right->items + i, push_space -
1165                                       btrfs_item_size(right->items + i));
1166                 push_space = btrfs_item_offset(right->items + i);
1167         }
1168         left_nritems -= push_items;
1169         btrfs_set_header_nritems(&left->header, left_nritems);
1170
1171         btrfs_mark_buffer_dirty(left_buf);
1172         btrfs_mark_buffer_dirty(right_buf);
1173
1174         btrfs_memcpy(root, upper_node, &upper_node->ptrs[slot + 1].key,
1175                 &right->items[0].key, sizeof(struct btrfs_disk_key));
1176         btrfs_mark_buffer_dirty(upper);
1177
1178         /* then fixup the leaf pointer in the path */
1179         if (path->slots[0] >= left_nritems) {
1180                 path->slots[0] -= left_nritems;
1181                 btrfs_block_release(root, path->nodes[0]);
1182                 path->nodes[0] = right_buf;
1183                 path->slots[1] += 1;
1184         } else {
1185                 btrfs_block_release(root, right_buf);
1186         }
1187         if (path->nodes[1])
1188                 check_node(root, path, 1);
1189         return 0;
1190 }
1191 /*
1192  * push some data in the path leaf to the left, trying to free up at
1193  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
1194  */
1195 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1196                           *root, struct btrfs_path *path, int data_size)
1197 {
1198         struct buffer_head *right_buf = path->nodes[0];
1199         struct btrfs_leaf *right = btrfs_buffer_leaf(right_buf);
1200         struct buffer_head *t;
1201         struct btrfs_leaf *left;
1202         int slot;
1203         int i;
1204         int free_space;
1205         int push_space = 0;
1206         int push_items = 0;
1207         struct btrfs_item *item;
1208         u32 old_left_nritems;
1209         int ret = 0;
1210         int wret;
1211
1212         slot = path->slots[1];
1213         if (slot == 0) {
1214                 return 1;
1215         }
1216         if (!path->nodes[1]) {
1217                 return 1;
1218         }
1219         t = read_tree_block(root,
1220             btrfs_node_blockptr(btrfs_buffer_node(path->nodes[1]), slot - 1));
1221         left = btrfs_buffer_leaf(t);
1222         free_space = btrfs_leaf_free_space(root, left);
1223         if (free_space < data_size + sizeof(struct btrfs_item)) {
1224                 btrfs_block_release(root, t);
1225                 return 1;
1226         }
1227
1228         /* cow and double check */
1229         ret = btrfs_cow_block(trans, root, t, path->nodes[1], slot - 1, &t);
1230         if (ret) {
1231                 /* we hit -ENOSPC, but it isn't fatal here */
1232                 return 1;
1233         }
1234         left = btrfs_buffer_leaf(t);
1235         free_space = btrfs_leaf_free_space(root, left);
1236         if (free_space < data_size + sizeof(struct btrfs_item)) {
1237                 btrfs_block_release(root, t);
1238                 return 1;
1239         }
1240
1241         if (btrfs_header_nritems(&right->header) == 0) {
1242                 btrfs_block_release(root, t);
1243                 return 1;
1244         }
1245
1246         for (i = 0; i < btrfs_header_nritems(&right->header) - 1; i++) {
1247                 item = right->items + i;
1248                 if (path->slots[0] == i)
1249                         push_space += data_size + sizeof(*item);
1250                 if (btrfs_item_size(item) + sizeof(*item) + push_space >
1251                     free_space)
1252                         break;
1253                 push_items++;
1254                 push_space += btrfs_item_size(item) + sizeof(*item);
1255         }
1256         if (push_items == 0) {
1257                 btrfs_block_release(root, t);
1258                 return 1;
1259         }
1260         if (push_items == btrfs_header_nritems(&right->header))
1261                 WARN_ON(1);
1262         /* push data from right to left */
1263         btrfs_memcpy(root, left, left->items +
1264                      btrfs_header_nritems(&left->header),
1265                      right->items, push_items * sizeof(struct btrfs_item));
1266         push_space = BTRFS_LEAF_DATA_SIZE(root) -
1267                      btrfs_item_offset(right->items + push_items -1);
1268         btrfs_memcpy(root, left, btrfs_leaf_data(left) +
1269                      leaf_data_end(root, left) - push_space,
1270                      btrfs_leaf_data(right) +
1271                      btrfs_item_offset(right->items + push_items - 1),
1272                      push_space);
1273         old_left_nritems = btrfs_header_nritems(&left->header);
1274         BUG_ON(old_left_nritems < 0);
1275
1276         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1277                 u32 ioff = btrfs_item_offset(left->items + i);
1278                 btrfs_set_item_offset(left->items + i, ioff -
1279                                      (BTRFS_LEAF_DATA_SIZE(root) -
1280                                       btrfs_item_offset(left->items +
1281                                                         old_left_nritems - 1)));
1282         }
1283         btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
1284
1285         /* fixup right node */
1286         push_space = btrfs_item_offset(right->items + push_items - 1) -
1287                      leaf_data_end(root, right);
1288         btrfs_memmove(root, right, btrfs_leaf_data(right) +
1289                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
1290                       btrfs_leaf_data(right) +
1291                       leaf_data_end(root, right), push_space);
1292         btrfs_memmove(root, right, right->items, right->items + push_items,
1293                 (btrfs_header_nritems(&right->header) - push_items) *
1294                 sizeof(struct btrfs_item));
1295         btrfs_set_header_nritems(&right->header,
1296                                  btrfs_header_nritems(&right->header) -
1297                                  push_items);
1298         push_space = BTRFS_LEAF_DATA_SIZE(root);
1299
1300         for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1301                 btrfs_set_item_offset(right->items + i, push_space -
1302                                       btrfs_item_size(right->items + i));
1303                 push_space = btrfs_item_offset(right->items + i);
1304         }
1305
1306         btrfs_mark_buffer_dirty(t);
1307         btrfs_mark_buffer_dirty(right_buf);
1308
1309         wret = fixup_low_keys(trans, root, path, &right->items[0].key, 1);
1310         if (wret)
1311                 ret = wret;
1312
1313         /* then fixup the leaf pointer in the path */
1314         if (path->slots[0] < push_items) {
1315                 path->slots[0] += old_left_nritems;
1316                 btrfs_block_release(root, path->nodes[0]);
1317                 path->nodes[0] = t;
1318                 path->slots[1] -= 1;
1319         } else {
1320                 btrfs_block_release(root, t);
1321                 path->slots[0] -= push_items;
1322         }
1323         BUG_ON(path->slots[0] < 0);
1324         if (path->nodes[1])
1325                 check_node(root, path, 1);
1326         return ret;
1327 }
1328
1329 /*
1330  * split the path's leaf in two, making sure there is at least data_size
1331  * available for the resulting leaf level of the path.
1332  *
1333  * returns 0 if all went well and < 0 on failure.
1334  */
1335 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1336                       *root, struct btrfs_key *ins_key,
1337                       struct btrfs_path *path, int data_size)
1338 {
1339         struct buffer_head *l_buf;
1340         struct btrfs_leaf *l;
1341         u32 nritems;
1342         int mid;
1343         int slot;
1344         struct btrfs_leaf *right;
1345         struct buffer_head *right_buffer;
1346         int space_needed = data_size + sizeof(struct btrfs_item);
1347         int data_copy_size;
1348         int rt_data_off;
1349         int i;
1350         int ret = 0;
1351         int wret;
1352         int double_split = 0;
1353         struct btrfs_disk_key disk_key;
1354
1355         /* first try to make some room by pushing left and right */
1356         wret = push_leaf_left(trans, root, path, data_size);
1357         if (wret < 0)
1358                 return wret;
1359         if (wret) {
1360                 wret = push_leaf_right(trans, root, path, data_size);
1361                 if (wret < 0)
1362                         return wret;
1363         }
1364         l_buf = path->nodes[0];
1365         l = btrfs_buffer_leaf(l_buf);
1366
1367         /* did the pushes work? */
1368         if (btrfs_leaf_free_space(root, l) >=
1369             sizeof(struct btrfs_item) + data_size)
1370                 return 0;
1371
1372         if (!path->nodes[1]) {
1373                 ret = insert_new_root(trans, root, path, 1);
1374                 if (ret)
1375                         return ret;
1376         }
1377         slot = path->slots[0];
1378         nritems = btrfs_header_nritems(&l->header);
1379         mid = (nritems + 1)/ 2;
1380
1381         right_buffer = btrfs_alloc_free_block(trans, root, l_buf->b_blocknr);
1382         if (IS_ERR(right_buffer))
1383                 return PTR_ERR(right_buffer);
1384
1385         right = btrfs_buffer_leaf(right_buffer);
1386         memset(&right->header, 0, sizeof(right->header));
1387         btrfs_set_header_blocknr(&right->header, bh_blocknr(right_buffer));
1388         btrfs_set_header_generation(&right->header, trans->transid);
1389         btrfs_set_header_owner(&right->header, root->root_key.objectid);
1390         btrfs_set_header_level(&right->header, 0);
1391         memcpy(right->header.fsid, root->fs_info->disk_super->fsid,
1392                sizeof(right->header.fsid));
1393         if (mid <= slot) {
1394                 if (nritems == 1 ||
1395                     leaf_space_used(l, mid, nritems - mid) + space_needed >
1396                         BTRFS_LEAF_DATA_SIZE(root)) {
1397                         if (slot >= nritems) {
1398                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1399                                 btrfs_set_header_nritems(&right->header, 0);
1400                                 wret = insert_ptr(trans, root, path,
1401                                                   &disk_key,
1402                                                   bh_blocknr(right_buffer),
1403                                                   path->slots[1] + 1, 1);
1404                                 if (wret)
1405                                         ret = wret;
1406                                 btrfs_block_release(root, path->nodes[0]);
1407                                 path->nodes[0] = right_buffer;
1408                                 path->slots[0] = 0;
1409                                 path->slots[1] += 1;
1410                                 return ret;
1411                         }
1412                         mid = slot;
1413                         double_split = 1;
1414                 }
1415         } else {
1416                 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1417                         BTRFS_LEAF_DATA_SIZE(root)) {
1418                         if (slot == 0) {
1419                                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1420                                 btrfs_set_header_nritems(&right->header, 0);
1421                                 wret = insert_ptr(trans, root, path,
1422                                                   &disk_key,
1423                                                   bh_blocknr(right_buffer),
1424                                                   path->slots[1], 1);
1425                                 if (wret)
1426                                         ret = wret;
1427                                 btrfs_block_release(root, path->nodes[0]);
1428                                 path->nodes[0] = right_buffer;
1429                                 path->slots[0] = 0;
1430                                 if (path->slots[1] == 0) {
1431                                         wret = fixup_low_keys(trans, root,
1432                                                    path, &disk_key, 1);
1433                                         if (wret)
1434                                                 ret = wret;
1435                                 }
1436                                 return ret;
1437                         }
1438                         mid = slot;
1439                         double_split = 1;
1440                 }
1441         }
1442         btrfs_set_header_nritems(&right->header, nritems - mid);
1443         data_copy_size = btrfs_item_end(l->items + mid) -
1444                          leaf_data_end(root, l);
1445         btrfs_memcpy(root, right, right->items, l->items + mid,
1446                      (nritems - mid) * sizeof(struct btrfs_item));
1447         btrfs_memcpy(root, right,
1448                      btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1449                      data_copy_size, btrfs_leaf_data(l) +
1450                      leaf_data_end(root, l), data_copy_size);
1451         rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1452                       btrfs_item_end(l->items + mid);
1453
1454         for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1455                 u32 ioff = btrfs_item_offset(right->items + i);
1456                 btrfs_set_item_offset(right->items + i, ioff + rt_data_off);
1457         }
1458
1459         btrfs_set_header_nritems(&l->header, mid);
1460         ret = 0;
1461         wret = insert_ptr(trans, root, path, &right->items[0].key,
1462                           bh_blocknr(right_buffer), path->slots[1] + 1, 1);
1463         if (wret)
1464                 ret = wret;
1465         btrfs_mark_buffer_dirty(right_buffer);
1466         btrfs_mark_buffer_dirty(l_buf);
1467         BUG_ON(path->slots[0] != slot);
1468         if (mid <= slot) {
1469                 btrfs_block_release(root, path->nodes[0]);
1470                 path->nodes[0] = right_buffer;
1471                 path->slots[0] -= mid;
1472                 path->slots[1] += 1;
1473         } else
1474                 btrfs_block_release(root, right_buffer);
1475         BUG_ON(path->slots[0] < 0);
1476         check_node(root, path, 1);
1477
1478         if (!double_split)
1479                 return ret;
1480         right_buffer = btrfs_alloc_free_block(trans, root, l_buf->b_blocknr);
1481         if (IS_ERR(right_buffer))
1482                 return PTR_ERR(right_buffer);
1483
1484         right = btrfs_buffer_leaf(right_buffer);
1485         memset(&right->header, 0, sizeof(right->header));
1486         btrfs_set_header_blocknr(&right->header, bh_blocknr(right_buffer));
1487         btrfs_set_header_generation(&right->header, trans->transid);
1488         btrfs_set_header_owner(&right->header, root->root_key.objectid);
1489         btrfs_set_header_level(&right->header, 0);
1490         memcpy(right->header.fsid, root->fs_info->disk_super->fsid,
1491                sizeof(right->header.fsid));
1492         btrfs_cpu_key_to_disk(&disk_key, ins_key);
1493         btrfs_set_header_nritems(&right->header, 0);
1494         wret = insert_ptr(trans, root, path,
1495                           &disk_key,
1496                           bh_blocknr(right_buffer),
1497                           path->slots[1], 1);
1498         if (wret)
1499                 ret = wret;
1500         if (path->slots[1] == 0) {
1501                 wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1502                 if (wret)
1503                         ret = wret;
1504         }
1505         btrfs_block_release(root, path->nodes[0]);
1506         path->nodes[0] = right_buffer;
1507         path->slots[0] = 0;
1508         check_node(root, path, 1);
1509         check_leaf(root, path, 0);
1510         return ret;
1511 }
1512
1513 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
1514                         struct btrfs_root *root,
1515                         struct btrfs_path *path,
1516                         u32 new_size)
1517 {
1518         int ret = 0;
1519         int slot;
1520         int slot_orig;
1521         struct btrfs_leaf *leaf;
1522         struct buffer_head *leaf_buf;
1523         u32 nritems;
1524         unsigned int data_end;
1525         unsigned int old_data_start;
1526         unsigned int old_size;
1527         unsigned int size_diff;
1528         int i;
1529
1530         slot_orig = path->slots[0];
1531         leaf_buf = path->nodes[0];
1532         leaf = btrfs_buffer_leaf(leaf_buf);
1533
1534         nritems = btrfs_header_nritems(&leaf->header);
1535         data_end = leaf_data_end(root, leaf);
1536
1537         slot = path->slots[0];
1538         old_data_start = btrfs_item_offset(leaf->items + slot);
1539         old_size = btrfs_item_size(leaf->items + slot);
1540         BUG_ON(old_size <= new_size);
1541         size_diff = old_size - new_size;
1542
1543         BUG_ON(slot < 0);
1544         BUG_ON(slot >= nritems);
1545
1546         /*
1547          * item0..itemN ... dataN.offset..dataN.size .. data0.size
1548          */
1549         /* first correct the data pointers */
1550         for (i = slot; i < nritems; i++) {
1551                 u32 ioff = btrfs_item_offset(leaf->items + i);
1552                 btrfs_set_item_offset(leaf->items + i,
1553                                       ioff + size_diff);
1554         }
1555         /* shift the data */
1556         btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
1557                       data_end + size_diff, btrfs_leaf_data(leaf) +
1558                       data_end, old_data_start + new_size - data_end);
1559         btrfs_set_item_size(leaf->items + slot, new_size);
1560         btrfs_mark_buffer_dirty(leaf_buf);
1561
1562         ret = 0;
1563         if (btrfs_leaf_free_space(root, leaf) < 0)
1564                 BUG();
1565         check_leaf(root, path, 0);
1566         return ret;
1567 }
1568
1569 int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root
1570                       *root, struct btrfs_path *path, u32 data_size)
1571 {
1572         int ret = 0;
1573         int slot;
1574         int slot_orig;
1575         struct btrfs_leaf *leaf;
1576         struct buffer_head *leaf_buf;
1577         u32 nritems;
1578         unsigned int data_end;
1579         unsigned int old_data;
1580         unsigned int old_size;
1581         int i;
1582
1583         slot_orig = path->slots[0];
1584         leaf_buf = path->nodes[0];
1585         leaf = btrfs_buffer_leaf(leaf_buf);
1586
1587         nritems = btrfs_header_nritems(&leaf->header);
1588         data_end = leaf_data_end(root, leaf);
1589
1590         if (btrfs_leaf_free_space(root, leaf) < data_size)
1591                 BUG();
1592         slot = path->slots[0];
1593         old_data = btrfs_item_end(leaf->items + slot);
1594
1595         BUG_ON(slot < 0);
1596         BUG_ON(slot >= nritems);
1597
1598         /*
1599          * item0..itemN ... dataN.offset..dataN.size .. data0.size
1600          */
1601         /* first correct the data pointers */
1602         for (i = slot; i < nritems; i++) {
1603                 u32 ioff = btrfs_item_offset(leaf->items + i);
1604                 btrfs_set_item_offset(leaf->items + i,
1605                                       ioff - data_size);
1606         }
1607         /* shift the data */
1608         btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
1609                       data_end - data_size, btrfs_leaf_data(leaf) +
1610                       data_end, old_data - data_end);
1611         data_end = old_data;
1612         old_size = btrfs_item_size(leaf->items + slot);
1613         btrfs_set_item_size(leaf->items + slot, old_size + data_size);
1614         btrfs_mark_buffer_dirty(leaf_buf);
1615
1616         ret = 0;
1617         if (btrfs_leaf_free_space(root, leaf) < 0)
1618                 BUG();
1619         check_leaf(root, path, 0);
1620         return ret;
1621 }
1622
1623 /*
1624  * Given a key and some data, insert an item into the tree.
1625  * This does all the path init required, making room in the tree if needed.
1626  */
1627 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
1628                             *root, struct btrfs_path *path, struct btrfs_key
1629                             *cpu_key, u32 data_size)
1630 {
1631         int ret = 0;
1632         int slot;
1633         int slot_orig;
1634         struct btrfs_leaf *leaf;
1635         struct buffer_head *leaf_buf;
1636         u32 nritems;
1637         unsigned int data_end;
1638         struct btrfs_disk_key disk_key;
1639
1640         btrfs_cpu_key_to_disk(&disk_key, cpu_key);
1641
1642         /* create a root if there isn't one */
1643         if (!root->node)
1644                 BUG();
1645         ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
1646         if (ret == 0) {
1647                 return -EEXIST;
1648         }
1649         if (ret < 0)
1650                 goto out;
1651
1652         slot_orig = path->slots[0];
1653         leaf_buf = path->nodes[0];
1654         leaf = btrfs_buffer_leaf(leaf_buf);
1655
1656         nritems = btrfs_header_nritems(&leaf->header);
1657         data_end = leaf_data_end(root, leaf);
1658
1659         if (btrfs_leaf_free_space(root, leaf) <
1660             sizeof(struct btrfs_item) + data_size) {
1661                 BUG();
1662         }
1663         slot = path->slots[0];
1664         BUG_ON(slot < 0);
1665         if (slot != nritems) {
1666                 int i;
1667                 unsigned int old_data = btrfs_item_end(leaf->items + slot);
1668
1669                 /*
1670                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
1671                  */
1672                 /* first correct the data pointers */
1673                 for (i = slot; i < nritems; i++) {
1674                         u32 ioff = btrfs_item_offset(leaf->items + i);
1675                         btrfs_set_item_offset(leaf->items + i,
1676                                               ioff - data_size);
1677                 }
1678
1679                 /* shift the items */
1680                 btrfs_memmove(root, leaf, leaf->items + slot + 1,
1681                               leaf->items + slot,
1682                               (nritems - slot) * sizeof(struct btrfs_item));
1683
1684                 /* shift the data */
1685                 btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
1686                               data_end - data_size, btrfs_leaf_data(leaf) +
1687                               data_end, old_data - data_end);
1688                 data_end = old_data;
1689         }
1690         /* setup the item for the new data */
1691         btrfs_memcpy(root, leaf, &leaf->items[slot].key, &disk_key,
1692                      sizeof(struct btrfs_disk_key));
1693         btrfs_set_item_offset(leaf->items + slot, data_end - data_size);
1694         btrfs_set_item_size(leaf->items + slot, data_size);
1695         btrfs_set_header_nritems(&leaf->header, nritems + 1);
1696         btrfs_mark_buffer_dirty(leaf_buf);
1697
1698         ret = 0;
1699         if (slot == 0)
1700                 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
1701
1702         if (btrfs_leaf_free_space(root, leaf) < 0)
1703                 BUG();
1704         check_leaf(root, path, 0);
1705 out:
1706         return ret;
1707 }
1708
1709 /*
1710  * Given a key and some data, insert an item into the tree.
1711  * This does all the path init required, making room in the tree if needed.
1712  */
1713 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
1714                       *root, struct btrfs_key *cpu_key, void *data, u32
1715                       data_size)
1716 {
1717         int ret = 0;
1718         struct btrfs_path *path;
1719         u8 *ptr;
1720
1721         path = btrfs_alloc_path();
1722         BUG_ON(!path);
1723         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
1724         if (!ret) {
1725                 ptr = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
1726                                      path->slots[0], u8);
1727                 btrfs_memcpy(root, path->nodes[0]->b_data,
1728                              ptr, data, data_size);
1729                 btrfs_mark_buffer_dirty(path->nodes[0]);
1730         }
1731         btrfs_free_path(path);
1732         return ret;
1733 }
1734
1735 /*
1736  * delete the pointer from a given node.
1737  *
1738  * If the delete empties a node, the node is removed from the tree,
1739  * continuing all the way the root if required.  The root is converted into
1740  * a leaf if all the nodes are emptied.
1741  */
1742 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1743                    struct btrfs_path *path, int level, int slot)
1744 {
1745         struct btrfs_node *node;
1746         struct buffer_head *parent = path->nodes[level];
1747         u32 nritems;
1748         int ret = 0;
1749         int wret;
1750
1751         node = btrfs_buffer_node(parent);
1752         nritems = btrfs_header_nritems(&node->header);
1753         if (slot != nritems -1) {
1754                 btrfs_memmove(root, node, node->ptrs + slot,
1755                               node->ptrs + slot + 1,
1756                               sizeof(struct btrfs_key_ptr) *
1757                               (nritems - slot - 1));
1758         }
1759         nritems--;
1760         btrfs_set_header_nritems(&node->header, nritems);
1761         if (nritems == 0 && parent == root->node) {
1762                 struct btrfs_header *header = btrfs_buffer_header(root->node);
1763                 BUG_ON(btrfs_header_level(header) != 1);
1764                 /* just turn the root into a leaf and break */
1765                 btrfs_set_header_level(header, 0);
1766         } else if (slot == 0) {
1767                 wret = fixup_low_keys(trans, root, path, &node->ptrs[0].key,
1768                                       level + 1);
1769                 if (wret)
1770                         ret = wret;
1771         }
1772         btrfs_mark_buffer_dirty(parent);
1773         return ret;
1774 }
1775
1776 /*
1777  * delete the item at the leaf level in path.  If that empties
1778  * the leaf, remove it from the tree
1779  */
1780 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1781                    struct btrfs_path *path)
1782 {
1783         int slot;
1784         struct btrfs_leaf *leaf;
1785         struct buffer_head *leaf_buf;
1786         int doff;
1787         int dsize;
1788         int ret = 0;
1789         int wret;
1790         u32 nritems;
1791
1792         leaf_buf = path->nodes[0];
1793         leaf = btrfs_buffer_leaf(leaf_buf);
1794         slot = path->slots[0];
1795         doff = btrfs_item_offset(leaf->items + slot);
1796         dsize = btrfs_item_size(leaf->items + slot);
1797         nritems = btrfs_header_nritems(&leaf->header);
1798
1799         if (slot != nritems - 1) {
1800                 int i;
1801                 int data_end = leaf_data_end(root, leaf);
1802                 btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
1803                               data_end + dsize,
1804                               btrfs_leaf_data(leaf) + data_end,
1805                               doff - data_end);
1806                 for (i = slot + 1; i < nritems; i++) {
1807                         u32 ioff = btrfs_item_offset(leaf->items + i);
1808                         btrfs_set_item_offset(leaf->items + i, ioff + dsize);
1809                 }
1810                 btrfs_memmove(root, leaf, leaf->items + slot,
1811                               leaf->items + slot + 1,
1812                               sizeof(struct btrfs_item) *
1813                               (nritems - slot - 1));
1814         }
1815         btrfs_set_header_nritems(&leaf->header, nritems - 1);
1816         nritems--;
1817         /* delete the leaf if we've emptied it */
1818         if (nritems == 0) {
1819                 if (leaf_buf == root->node) {
1820                         btrfs_set_header_level(&leaf->header, 0);
1821                 } else {
1822                         clean_tree_block(trans, root, leaf_buf);
1823                         wait_on_buffer(leaf_buf);
1824                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
1825                         if (wret)
1826                                 ret = wret;
1827                         wret = btrfs_free_extent(trans, root,
1828                                                  bh_blocknr(leaf_buf), 1, 1);
1829                         if (wret)
1830                                 ret = wret;
1831                 }
1832         } else {
1833                 int used = leaf_space_used(leaf, 0, nritems);
1834                 if (slot == 0) {
1835                         wret = fixup_low_keys(trans, root, path,
1836                                               &leaf->items[0].key, 1);
1837                         if (wret)
1838                                 ret = wret;
1839                 }
1840
1841                 /* delete the leaf if it is mostly empty */
1842                 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
1843                         /* push_leaf_left fixes the path.
1844                          * make sure the path still points to our leaf
1845                          * for possible call to del_ptr below
1846                          */
1847                         slot = path->slots[1];
1848                         get_bh(leaf_buf);
1849                         wret = push_leaf_left(trans, root, path, 1);
1850                         if (wret < 0 && wret != -ENOSPC)
1851                                 ret = wret;
1852                         if (path->nodes[0] == leaf_buf &&
1853                             btrfs_header_nritems(&leaf->header)) {
1854                                 wret = push_leaf_right(trans, root, path, 1);
1855                                 if (wret < 0 && wret != -ENOSPC)
1856                                         ret = wret;
1857                         }
1858                         if (btrfs_header_nritems(&leaf->header) == 0) {
1859                                 u64 blocknr = bh_blocknr(leaf_buf);
1860                                 clean_tree_block(trans, root, leaf_buf);
1861                                 wait_on_buffer(leaf_buf);
1862                                 wret = del_ptr(trans, root, path, 1, slot);
1863                                 if (wret)
1864                                         ret = wret;
1865                                 btrfs_block_release(root, leaf_buf);
1866                                 wret = btrfs_free_extent(trans, root, blocknr,
1867                                                          1, 1);
1868                                 if (wret)
1869                                         ret = wret;
1870                         } else {
1871                                 btrfs_mark_buffer_dirty(leaf_buf);
1872                                 btrfs_block_release(root, leaf_buf);
1873                         }
1874                 } else {
1875                         btrfs_mark_buffer_dirty(leaf_buf);
1876                 }
1877         }
1878         return ret;
1879 }
1880
1881 /*
1882  * walk up the tree as far as required to find the next leaf.
1883  * returns 0 if it found something or 1 if there are no greater leaves.
1884  * returns < 0 on io errors.
1885  */
1886 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
1887 {
1888         int slot;
1889         int level = 1;
1890         u64 blocknr;
1891         struct buffer_head *c;
1892         struct btrfs_node *c_node;
1893         struct buffer_head *next = NULL;
1894
1895         while(level < BTRFS_MAX_LEVEL) {
1896                 if (!path->nodes[level])
1897                         return 1;
1898                 slot = path->slots[level] + 1;
1899                 c = path->nodes[level];
1900                 c_node = btrfs_buffer_node(c);
1901                 if (slot >= btrfs_header_nritems(&c_node->header)) {
1902                         level++;
1903                         continue;
1904                 }
1905                 blocknr = btrfs_node_blockptr(c_node, slot);
1906                 if (next)
1907                         btrfs_block_release(root, next);
1908                 next = read_tree_block(root, blocknr);
1909                 break;
1910         }
1911         path->slots[level] = slot;
1912         while(1) {
1913                 level--;
1914                 c = path->nodes[level];
1915                 btrfs_block_release(root, c);
1916                 path->nodes[level] = next;
1917                 path->slots[level] = 0;
1918                 if (!level)
1919                         break;
1920                 next = read_tree_block(root,
1921                        btrfs_node_blockptr(btrfs_buffer_node(next), 0));
1922         }
1923         return 0;
1924 }