fs/btrfs/ctree.c

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