1 /* 2 * Copyright (c) 2007-2008 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $DragonFly: src/sys/vfs/hammer/hammer_cursor.c,v 1.42 2008/08/06 15:38:58 dillon Exp $ 35 */ 36 37 /* 38 * HAMMER B-Tree index - cursor support routines 39 */ 40 #include "hammer.h" 41 42 static int hammer_load_cursor_parent(hammer_cursor_t cursor, int try_exclusive); 43 44 /* 45 * Initialize a fresh cursor using the B-Tree node cache. If the cache 46 * is not available initialize a fresh cursor at the root of the filesystem. 47 */ 48 int 49 hammer_init_cursor(hammer_transaction_t trans, hammer_cursor_t cursor, 50 hammer_node_cache_t cache, hammer_inode_t ip) 51 { 52 hammer_volume_t volume; 53 hammer_node_t node; 54 int error; 55 56 bzero(cursor, sizeof(*cursor)); 57 58 cursor->trans = trans; 59 60 /* 61 * If the cursor operation is on behalf of an inode, lock 62 * the inode. 63 */ 64 if ((cursor->ip = ip) != NULL) { 65 ++ip->cursor_ip_refs; 66 if (trans->type == HAMMER_TRANS_FLS) 67 hammer_lock_ex(&ip->lock); 68 else 69 hammer_lock_sh(&ip->lock); 70 } 71 72 /* 73 * Step 1 - acquire a locked node from the cache if possible 74 */ 75 if (cache && cache->node) { 76 node = hammer_ref_node_safe(trans, cache, &error); 77 if (error == 0) { 78 hammer_lock_sh(&node->lock); 79 if (node->flags & HAMMER_NODE_DELETED) { 80 hammer_unlock(&node->lock); 81 hammer_rel_node(node); 82 node = NULL; 83 } 84 } 85 if (node == NULL) 86 ++hammer_stats_btree_root_iterations; 87 } else { 88 node = NULL; 89 ++hammer_stats_btree_root_iterations; 90 } 91 92 /* 93 * Step 2 - If we couldn't get a node from the cache, get 94 * the one from the root of the filesystem. 95 */ 96 while (node == NULL) { 97 volume = hammer_get_root_volume(trans->hmp, &error); 98 if (error) 99 break; 100 node = hammer_get_node(trans, volume->ondisk->vol0_btree_root, 101 0, &error); 102 hammer_rel_volume(volume, 0); 103 if (error) 104 break; 105 hammer_lock_sh(&node->lock); 106 107 /* 108 * If someone got in before we could lock the node, retry. 109 */ 110 if (node->flags & HAMMER_NODE_DELETED) { 111 hammer_unlock(&node->lock); 112 hammer_rel_node(node); 113 node = NULL; 114 continue; 115 } 116 if (volume->ondisk->vol0_btree_root != node->node_offset) { 117 hammer_unlock(&node->lock); 118 hammer_rel_node(node); 119 node = NULL; 120 continue; 121 } 122 } 123 124 /* 125 * Step 3 - finish initializing the cursor by acquiring the parent 126 */ 127 cursor->node = node; 128 if (error == 0) 129 error = hammer_load_cursor_parent(cursor, 0); 130 KKASSERT(error == 0); 131 /* if (error) hammer_done_cursor(cursor); */ 132 return(error); 133 } 134 135 /* 136 * Normalize a cursor. Sometimes cursors can be left in a state 137 * where node is NULL. If the cursor is in this state, cursor up. 138 */ 139 void 140 hammer_normalize_cursor(hammer_cursor_t cursor) 141 { 142 if (cursor->node == NULL) { 143 KKASSERT(cursor->parent != NULL); 144 hammer_cursor_up(cursor); 145 } 146 } 147 148 149 /* 150 * We are finished with a cursor. We NULL out various fields as sanity 151 * check, in case the structure is inappropriately used afterwords. 152 */ 153 void 154 hammer_done_cursor(hammer_cursor_t cursor) 155 { 156 hammer_inode_t ip; 157 158 KKASSERT((cursor->flags & HAMMER_CURSOR_TRACKED) == 0); 159 if (cursor->parent) { 160 hammer_unlock(&cursor->parent->lock); 161 hammer_rel_node(cursor->parent); 162 cursor->parent = NULL; 163 } 164 if (cursor->node) { 165 hammer_unlock(&cursor->node->lock); 166 hammer_rel_node(cursor->node); 167 cursor->node = NULL; 168 } 169 if (cursor->data_buffer) { 170 hammer_rel_buffer(cursor->data_buffer, 0); 171 cursor->data_buffer = NULL; 172 } 173 if ((ip = cursor->ip) != NULL) { 174 KKASSERT(ip->cursor_ip_refs > 0); 175 --ip->cursor_ip_refs; 176 hammer_unlock(&ip->lock); 177 cursor->ip = NULL; 178 } 179 if (cursor->iprec) { 180 hammer_rel_mem_record(cursor->iprec); 181 cursor->iprec = NULL; 182 } 183 184 /* 185 * If we deadlocked this node will be referenced. Do a quick 186 * lock/unlock to wait for the deadlock condition to clear. 187 */ 188 if (cursor->deadlk_node) { 189 hammer_lock_ex_ident(&cursor->deadlk_node->lock, "hmrdlk"); 190 hammer_unlock(&cursor->deadlk_node->lock); 191 hammer_rel_node(cursor->deadlk_node); 192 cursor->deadlk_node = NULL; 193 } 194 if (cursor->deadlk_rec) { 195 hammer_wait_mem_record_ident(cursor->deadlk_rec, "hmmdlr"); 196 hammer_rel_mem_record(cursor->deadlk_rec); 197 cursor->deadlk_rec = NULL; 198 } 199 200 cursor->data = NULL; 201 cursor->leaf = NULL; 202 cursor->left_bound = NULL; 203 cursor->right_bound = NULL; 204 cursor->trans = NULL; 205 } 206 207 /* 208 * Upgrade cursor->node and cursor->parent to exclusive locks. This 209 * function can return EDEADLK. 210 * 211 * The lock must already be either held shared or already held exclusively 212 * by us. 213 * 214 * If we fail to upgrade the lock and cursor->deadlk_node is NULL, 215 * we add another reference to the node that failed and set 216 * cursor->deadlk_node so hammer_done_cursor() can block on it. 217 */ 218 int 219 hammer_cursor_upgrade(hammer_cursor_t cursor) 220 { 221 int error; 222 223 error = hammer_lock_upgrade(&cursor->node->lock); 224 if (error && cursor->deadlk_node == NULL) { 225 cursor->deadlk_node = cursor->node; 226 hammer_ref_node(cursor->deadlk_node); 227 } else if (error == 0 && cursor->parent) { 228 error = hammer_lock_upgrade(&cursor->parent->lock); 229 if (error && cursor->deadlk_node == NULL) { 230 cursor->deadlk_node = cursor->parent; 231 hammer_ref_node(cursor->deadlk_node); 232 } 233 } 234 return(error); 235 } 236 237 int 238 hammer_cursor_upgrade_node(hammer_cursor_t cursor) 239 { 240 int error; 241 242 error = hammer_lock_upgrade(&cursor->node->lock); 243 if (error && cursor->deadlk_node == NULL) { 244 cursor->deadlk_node = cursor->node; 245 hammer_ref_node(cursor->deadlk_node); 246 } 247 return(error); 248 } 249 250 /* 251 * Downgrade cursor->node and cursor->parent to shared locks. This 252 * function can return EDEADLK. 253 */ 254 void 255 hammer_cursor_downgrade(hammer_cursor_t cursor) 256 { 257 if (hammer_lock_excl_owned(&cursor->node->lock, curthread)) 258 hammer_lock_downgrade(&cursor->node->lock); 259 if (cursor->parent && 260 hammer_lock_excl_owned(&cursor->parent->lock, curthread)) { 261 hammer_lock_downgrade(&cursor->parent->lock); 262 } 263 } 264 265 /* 266 * Seek the cursor to the specified node and index. 267 * 268 * The caller must ref the node prior to calling this routine and release 269 * it after it returns. If the seek succeeds the cursor will gain its own 270 * ref on the node. 271 */ 272 int 273 hammer_cursor_seek(hammer_cursor_t cursor, hammer_node_t node, int index) 274 { 275 int error; 276 277 hammer_cursor_downgrade(cursor); 278 error = 0; 279 280 if (cursor->node != node) { 281 hammer_unlock(&cursor->node->lock); 282 hammer_rel_node(cursor->node); 283 cursor->node = node; 284 hammer_ref_node(node); 285 hammer_lock_sh(&node->lock); 286 KKASSERT ((node->flags & HAMMER_NODE_DELETED) == 0); 287 288 if (cursor->parent) { 289 hammer_unlock(&cursor->parent->lock); 290 hammer_rel_node(cursor->parent); 291 cursor->parent = NULL; 292 cursor->parent_index = 0; 293 } 294 error = hammer_load_cursor_parent(cursor, 0); 295 } 296 cursor->index = index; 297 return (error); 298 } 299 300 /* 301 * Load the parent of cursor->node into cursor->parent. 302 */ 303 static 304 int 305 hammer_load_cursor_parent(hammer_cursor_t cursor, int try_exclusive) 306 { 307 hammer_mount_t hmp; 308 hammer_node_t parent; 309 hammer_node_t node; 310 hammer_btree_elm_t elm; 311 int error; 312 int parent_index; 313 314 hmp = cursor->trans->hmp; 315 316 if (cursor->node->ondisk->parent) { 317 node = cursor->node; 318 parent = hammer_btree_get_parent(cursor->trans, node, 319 &parent_index, 320 &error, try_exclusive); 321 if (error == 0) { 322 elm = &parent->ondisk->elms[parent_index]; 323 cursor->parent = parent; 324 cursor->parent_index = parent_index; 325 cursor->left_bound = &elm[0].internal.base; 326 cursor->right_bound = &elm[1].internal.base; 327 } 328 } else { 329 cursor->parent = NULL; 330 cursor->parent_index = 0; 331 cursor->left_bound = &hmp->root_btree_beg; 332 cursor->right_bound = &hmp->root_btree_end; 333 error = 0; 334 } 335 return(error); 336 } 337 338 /* 339 * Cursor up to our parent node. Return ENOENT if we are at the root of 340 * the filesystem. 341 */ 342 int 343 hammer_cursor_up(hammer_cursor_t cursor) 344 { 345 int error; 346 347 hammer_cursor_downgrade(cursor); 348 349 /* 350 * If the parent is NULL we are at the root of the B-Tree and 351 * return ENOENT. 352 */ 353 if (cursor->parent == NULL) 354 return (ENOENT); 355 356 /* 357 * Set the node to its parent. 358 */ 359 hammer_unlock(&cursor->node->lock); 360 hammer_rel_node(cursor->node); 361 cursor->node = cursor->parent; 362 cursor->index = cursor->parent_index; 363 cursor->parent = NULL; 364 cursor->parent_index = 0; 365 366 error = hammer_load_cursor_parent(cursor, 0); 367 return(error); 368 } 369 370 /* 371 * Special cursor up given a locked cursor. The orignal node is not 372 * unlocked or released and the cursor is not downgraded. 373 * 374 * This function will recover from deadlocks. EDEADLK cannot be returned. 375 */ 376 int 377 hammer_cursor_up_locked(hammer_cursor_t cursor) 378 { 379 hammer_node_t save; 380 int error; 381 382 /* 383 * If the parent is NULL we are at the root of the B-Tree and 384 * return ENOENT. 385 */ 386 if (cursor->parent == NULL) 387 return (ENOENT); 388 389 save = cursor->node; 390 391 /* 392 * Set the node to its parent. 393 */ 394 cursor->node = cursor->parent; 395 cursor->index = cursor->parent_index; 396 cursor->parent = NULL; 397 cursor->parent_index = 0; 398 399 /* 400 * load the new parent, attempt to exclusively lock it. Note that 401 * we are still holding the old parent (now cursor->node) exclusively 402 * locked. This can return EDEADLK. 403 */ 404 error = hammer_load_cursor_parent(cursor, 1); 405 if (error) { 406 cursor->parent = cursor->node; 407 cursor->parent_index = cursor->index; 408 cursor->node = save; 409 cursor->index = 0; 410 } 411 return(error); 412 } 413 414 415 /* 416 * Cursor down through the current node, which must be an internal node. 417 * 418 * This routine adjusts the cursor and sets index to 0. 419 */ 420 int 421 hammer_cursor_down(hammer_cursor_t cursor) 422 { 423 hammer_node_t node; 424 hammer_btree_elm_t elm; 425 int error; 426 427 /* 428 * The current node becomes the current parent 429 */ 430 hammer_cursor_downgrade(cursor); 431 node = cursor->node; 432 KKASSERT(cursor->index >= 0 && cursor->index < node->ondisk->count); 433 if (cursor->parent) { 434 hammer_unlock(&cursor->parent->lock); 435 hammer_rel_node(cursor->parent); 436 } 437 cursor->parent = node; 438 cursor->parent_index = cursor->index; 439 cursor->node = NULL; 440 cursor->index = 0; 441 442 /* 443 * Extract element to push into at (node,index), set bounds. 444 */ 445 elm = &node->ondisk->elms[cursor->parent_index]; 446 447 /* 448 * Ok, push down into elm. If elm specifies an internal or leaf 449 * node the current node must be an internal node. If elm specifies 450 * a spike then the current node must be a leaf node. 451 */ 452 switch(elm->base.btype) { 453 case HAMMER_BTREE_TYPE_INTERNAL: 454 case HAMMER_BTREE_TYPE_LEAF: 455 KKASSERT(node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL); 456 KKASSERT(elm->internal.subtree_offset != 0); 457 cursor->left_bound = &elm[0].internal.base; 458 cursor->right_bound = &elm[1].internal.base; 459 node = hammer_get_node(cursor->trans, 460 elm->internal.subtree_offset, 0, &error); 461 if (error == 0) { 462 KASSERT(elm->base.btype == node->ondisk->type, ("BTYPE MISMATCH %c %c NODE %p\n", elm->base.btype, node->ondisk->type, node)); 463 if (node->ondisk->parent != cursor->parent->node_offset) 464 panic("node %p %016llx vs %016llx\n", node, (long long)node->ondisk->parent, (long long)cursor->parent->node_offset); 465 KKASSERT(node->ondisk->parent == cursor->parent->node_offset); 466 } 467 break; 468 default: 469 panic("hammer_cursor_down: illegal btype %02x (%c)\n", 470 elm->base.btype, 471 (elm->base.btype ? elm->base.btype : '?')); 472 break; 473 } 474 if (error == 0) { 475 hammer_lock_sh(&node->lock); 476 KKASSERT ((node->flags & HAMMER_NODE_DELETED) == 0); 477 cursor->node = node; 478 cursor->index = 0; 479 } 480 return(error); 481 } 482 483 /************************************************************************ 484 * DEADLOCK RECOVERY * 485 ************************************************************************ 486 * 487 * These are the new deadlock recovery functions. Currently they are only 488 * used for the mirror propagation and physical node removal cases but 489 * ultimately the intention is to use them for all deadlock recovery 490 * operations. 491 */ 492 void 493 hammer_unlock_cursor(hammer_cursor_t cursor) 494 { 495 hammer_node_t node; 496 497 KKASSERT((cursor->flags & HAMMER_CURSOR_TRACKED) == 0); 498 KKASSERT(cursor->node); 499 500 /* 501 * Release the cursor's locks and track B-Tree operations on node. 502 * While being tracked our cursor can be modified by other threads 503 * and the node may be replaced. 504 */ 505 if (cursor->parent) { 506 hammer_unlock(&cursor->parent->lock); 507 hammer_rel_node(cursor->parent); 508 cursor->parent = NULL; 509 } 510 node = cursor->node; 511 cursor->flags |= HAMMER_CURSOR_TRACKED; 512 TAILQ_INSERT_TAIL(&node->cursor_list, cursor, deadlk_entry); 513 hammer_unlock(&node->lock); 514 } 515 516 /* 517 * Get the cursor heated up again. The cursor's node may have 518 * changed and we might have to locate the new parent. 519 * 520 * If the exact element we were on got deleted RIPOUT will be 521 * set and we must clear ATEDISK so an iteration does not skip 522 * the element after it. 523 */ 524 int 525 hammer_lock_cursor(hammer_cursor_t cursor) 526 { 527 hammer_node_t node; 528 int error; 529 530 KKASSERT(cursor->flags & HAMMER_CURSOR_TRACKED); 531 532 /* 533 * Relock the node 534 */ 535 for (;;) { 536 node = cursor->node; 537 hammer_ref_node(node); 538 hammer_lock_sh(&node->lock); 539 if (cursor->node == node) { 540 hammer_rel_node(node); 541 break; 542 } 543 hammer_unlock(&node->lock); 544 hammer_rel_node(node); 545 } 546 547 /* 548 * Untrack the cursor, clean up, and re-establish the parent node. 549 */ 550 TAILQ_REMOVE(&node->cursor_list, cursor, deadlk_entry); 551 cursor->flags &= ~HAMMER_CURSOR_TRACKED; 552 553 /* 554 * If a ripout has occured iterations must re-test the (new) 555 * current element. Clearing ATEDISK prevents the element from 556 * being skipped and RETEST causes it to be re-tested. 557 */ 558 if (cursor->flags & HAMMER_CURSOR_TRACKED_RIPOUT) { 559 cursor->flags &= ~HAMMER_CURSOR_TRACKED_RIPOUT; 560 cursor->flags &= ~HAMMER_CURSOR_ATEDISK; 561 cursor->flags |= HAMMER_CURSOR_RETEST; 562 } 563 error = hammer_load_cursor_parent(cursor, 0); 564 return(error); 565 } 566 567 /* 568 * Recover from a deadlocked cursor, tracking any node removals or 569 * replacements. If the cursor's current node is removed by another 570 * thread (via btree_remove()) the cursor will be seeked upwards. 571 * 572 * The caller is working a modifying operation and must be holding the 573 * sync lock (shared). We do not release the sync lock because this 574 * would break atomicy. 575 */ 576 int 577 hammer_recover_cursor(hammer_cursor_t cursor) 578 { 579 int error; 580 581 hammer_unlock_cursor(cursor); 582 KKASSERT(cursor->trans->sync_lock_refs > 0); 583 584 /* 585 * Wait for the deadlock to clear 586 */ 587 if (cursor->deadlk_node) { 588 hammer_lock_ex_ident(&cursor->deadlk_node->lock, "hmrdlk"); 589 hammer_unlock(&cursor->deadlk_node->lock); 590 hammer_rel_node(cursor->deadlk_node); 591 cursor->deadlk_node = NULL; 592 } 593 if (cursor->deadlk_rec) { 594 hammer_wait_mem_record_ident(cursor->deadlk_rec, "hmmdlr"); 595 hammer_rel_mem_record(cursor->deadlk_rec); 596 cursor->deadlk_rec = NULL; 597 } 598 error = hammer_lock_cursor(cursor); 599 return(error); 600 } 601 602 /* 603 * Dup ocursor to ncursor. ncursor inherits ocursor's locks and ocursor 604 * is effectively unlocked and becomes tracked. If ocursor was not locked 605 * then ncursor also inherits the tracking. 606 * 607 * After the caller finishes working with ncursor it must be cleaned up 608 * with hammer_done_cursor(), and the caller must re-lock ocursor. 609 */ 610 hammer_cursor_t 611 hammer_push_cursor(hammer_cursor_t ocursor) 612 { 613 hammer_cursor_t ncursor; 614 hammer_inode_t ip; 615 hammer_node_t node; 616 hammer_mount_t hmp; 617 618 hmp = ocursor->trans->hmp; 619 ncursor = kmalloc(sizeof(*ncursor), hmp->m_misc, M_WAITOK | M_ZERO); 620 bcopy(ocursor, ncursor, sizeof(*ocursor)); 621 622 node = ocursor->node; 623 hammer_ref_node(node); 624 if ((ocursor->flags & HAMMER_CURSOR_TRACKED) == 0) { 625 ocursor->flags |= HAMMER_CURSOR_TRACKED; 626 TAILQ_INSERT_TAIL(&node->cursor_list, ocursor, deadlk_entry); 627 } 628 if (ncursor->parent) 629 ocursor->parent = NULL; 630 ocursor->data_buffer = NULL; 631 ocursor->leaf = NULL; 632 ocursor->data = NULL; 633 if (ncursor->flags & HAMMER_CURSOR_TRACKED) 634 TAILQ_INSERT_TAIL(&node->cursor_list, ncursor, deadlk_entry); 635 if ((ip = ncursor->ip) != NULL) { 636 ++ip->cursor_ip_refs; 637 } 638 if (ncursor->iprec) 639 hammer_ref(&ncursor->iprec->lock); 640 return(ncursor); 641 } 642 643 /* 644 * Destroy ncursor and restore ocursor 645 * 646 * This is a temporary hack for the release. We can't afford to lose 647 * the IP lock until the IP object scan code is able to deal with it, 648 * so have ocursor inherit it back. 649 */ 650 void 651 hammer_pop_cursor(hammer_cursor_t ocursor, hammer_cursor_t ncursor) 652 { 653 hammer_mount_t hmp; 654 hammer_inode_t ip; 655 656 hmp = ncursor->trans->hmp; 657 ip = ncursor->ip; 658 ncursor->ip = NULL; 659 if (ip) 660 --ip->cursor_ip_refs; 661 hammer_done_cursor(ncursor); 662 kfree(ncursor, hmp->m_misc); 663 KKASSERT(ocursor->ip == ip); 664 hammer_lock_cursor(ocursor); 665 } 666 667 /* 668 * onode is being replaced by nnode by the reblocking code. 669 */ 670 void 671 hammer_cursor_replaced_node(hammer_node_t onode, hammer_node_t nnode) 672 { 673 hammer_cursor_t cursor; 674 675 while ((cursor = TAILQ_FIRST(&onode->cursor_list)) != NULL) { 676 TAILQ_REMOVE(&onode->cursor_list, cursor, deadlk_entry); 677 TAILQ_INSERT_TAIL(&nnode->cursor_list, cursor, deadlk_entry); 678 KKASSERT(cursor->node == onode); 679 cursor->node = nnode; 680 hammer_ref_node(nnode); 681 hammer_rel_node(onode); 682 } 683 } 684 685 /* 686 * node is being removed, cursors in deadlock recovery are seeked upward 687 * to the parent. 688 */ 689 void 690 hammer_cursor_removed_node(hammer_node_t node, hammer_node_t parent, int index) 691 { 692 hammer_cursor_t cursor; 693 694 KKASSERT(parent != NULL); 695 while ((cursor = TAILQ_FIRST(&node->cursor_list)) != NULL) { 696 KKASSERT(cursor->node == node); 697 KKASSERT(cursor->index == 0); 698 TAILQ_REMOVE(&node->cursor_list, cursor, deadlk_entry); 699 TAILQ_INSERT_TAIL(&parent->cursor_list, cursor, deadlk_entry); 700 cursor->flags |= HAMMER_CURSOR_TRACKED_RIPOUT; 701 cursor->node = parent; 702 cursor->index = index; 703 hammer_ref_node(parent); 704 hammer_rel_node(node); 705 } 706 } 707 708 /* 709 * node was split at (onode, index) with elements >= index moved to nnode. 710 */ 711 void 712 hammer_cursor_split_node(hammer_node_t onode, hammer_node_t nnode, int index) 713 { 714 hammer_cursor_t cursor; 715 716 again: 717 TAILQ_FOREACH(cursor, &onode->cursor_list, deadlk_entry) { 718 KKASSERT(cursor->node == onode); 719 if (cursor->index < index) 720 continue; 721 TAILQ_REMOVE(&onode->cursor_list, cursor, deadlk_entry); 722 TAILQ_INSERT_TAIL(&nnode->cursor_list, cursor, deadlk_entry); 723 cursor->node = nnode; 724 cursor->index -= index; 725 hammer_ref_node(nnode); 726 hammer_rel_node(onode); 727 goto again; 728 } 729 } 730 731 /* 732 * An element was moved from one node to another or within a node. The 733 * index may also represent the end of the node (index == numelements). 734 * 735 * This is used by the rebalancing code. This is not an insertion or 736 * deletion and any additional elements, including the degenerate case at 737 * the end of the node, will be dealt with by additional distinct calls. 738 */ 739 void 740 hammer_cursor_moved_element(hammer_node_t onode, hammer_node_t nnode, 741 int oindex, int nindex) 742 { 743 hammer_cursor_t cursor; 744 745 again: 746 TAILQ_FOREACH(cursor, &onode->cursor_list, deadlk_entry) { 747 KKASSERT(cursor->node == onode); 748 if (cursor->index != oindex) 749 continue; 750 TAILQ_REMOVE(&onode->cursor_list, cursor, deadlk_entry); 751 TAILQ_INSERT_TAIL(&nnode->cursor_list, cursor, deadlk_entry); 752 cursor->node = nnode; 753 cursor->index = nindex; 754 hammer_ref_node(nnode); 755 hammer_rel_node(onode); 756 goto again; 757 } 758 } 759 760 /* 761 * The B-Tree element pointing to the specified node was moved from (oparent) 762 * to (nparent, nindex). We must locate any tracked cursors pointing at 763 * node and adjust their parent accordingly. 764 * 765 * This is used by the rebalancing code when packing elements causes an 766 * element to shift from one node to another. 767 */ 768 void 769 hammer_cursor_parent_changed(hammer_node_t node, hammer_node_t oparent, 770 hammer_node_t nparent, int nindex) 771 { 772 hammer_cursor_t cursor; 773 774 again: 775 TAILQ_FOREACH(cursor, &node->cursor_list, deadlk_entry) { 776 KKASSERT(cursor->node == node); 777 if (cursor->parent == oparent) { 778 cursor->parent = nparent; 779 cursor->parent_index = nindex; 780 hammer_ref_node(nparent); 781 hammer_rel_node(oparent); 782 goto again; 783 } 784 } 785 } 786 787 /* 788 * Deleted element at (node, index) 789 * 790 * Shift indexes >= index 791 */ 792 void 793 hammer_cursor_deleted_element(hammer_node_t node, int index) 794 { 795 hammer_cursor_t cursor; 796 797 TAILQ_FOREACH(cursor, &node->cursor_list, deadlk_entry) { 798 KKASSERT(cursor->node == node); 799 if (cursor->index == index) { 800 cursor->flags |= HAMMER_CURSOR_TRACKED_RIPOUT; 801 } else if (cursor->index > index) { 802 --cursor->index; 803 } 804 } 805 } 806 807 /* 808 * Inserted element at (node, index) 809 * 810 * Shift indexes >= index 811 */ 812 void 813 hammer_cursor_inserted_element(hammer_node_t node, int index) 814 { 815 hammer_cursor_t cursor; 816 817 TAILQ_FOREACH(cursor, &node->cursor_list, deadlk_entry) { 818 KKASSERT(cursor->node == node); 819 if (cursor->index >= index) 820 ++cursor->index; 821 } 822 } 823 824