fs/btrfs/ctree.c

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