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 can fail with EDEADLK. 375 * 376 * This function is only run when recursively deleting parent nodes 377 * to get rid of an empty leaf. 378 */ 379 int 380 hammer_cursor_up_locked(hammer_cursor_t cursor) 381 { 382 hammer_node_t save; 383 int error; 384 int save_index; 385 386 /* 387 * If the parent is NULL we are at the root of the B-Tree and 388 * return ENOENT. 389 */ 390 if (cursor->parent == NULL) 391 return (ENOENT); 392 393 save = cursor->node; 394 save_index = cursor->index; 395 396 /* 397 * Set the node to its parent. 398 */ 399 cursor->node = cursor->parent; 400 cursor->index = cursor->parent_index; 401 cursor->parent = NULL; 402 cursor->parent_index = 0; 403 404 /* 405 * load the new parent, attempt to exclusively lock it. Note that 406 * we are still holding the old parent (now cursor->node) exclusively 407 * locked. 408 * 409 * This can return EDEADLK. Undo the operation on any error. These 410 * up sequences can occur during iterations so be sure to restore 411 * the index. 412 */ 413 error = hammer_load_cursor_parent(cursor, 1); 414 if (error) { 415 cursor->parent = cursor->node; 416 cursor->parent_index = cursor->index; 417 cursor->node = save; 418 cursor->index = save_index; 419 } 420 return(error); 421 } 422 423 424 /* 425 * Cursor down through the current node, which must be an internal node. 426 * 427 * This routine adjusts the cursor and sets index to 0. 428 */ 429 int 430 hammer_cursor_down(hammer_cursor_t cursor) 431 { 432 hammer_node_t node; 433 hammer_btree_elm_t elm; 434 int error; 435 436 /* 437 * The current node becomes the current parent 438 */ 439 hammer_cursor_downgrade(cursor); 440 node = cursor->node; 441 KKASSERT(cursor->index >= 0 && cursor->index < node->ondisk->count); 442 if (cursor->parent) { 443 hammer_unlock(&cursor->parent->lock); 444 hammer_rel_node(cursor->parent); 445 } 446 cursor->parent = node; 447 cursor->parent_index = cursor->index; 448 cursor->node = NULL; 449 cursor->index = 0; 450 451 /* 452 * Extract element to push into at (node,index), set bounds. 453 */ 454 elm = &node->ondisk->elms[cursor->parent_index]; 455 456 /* 457 * Ok, push down into elm. If elm specifies an internal or leaf 458 * node the current node must be an internal node. If elm specifies 459 * a spike then the current node must be a leaf node. 460 */ 461 switch(elm->base.btype) { 462 case HAMMER_BTREE_TYPE_INTERNAL: 463 case HAMMER_BTREE_TYPE_LEAF: 464 KKASSERT(node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL); 465 KKASSERT(elm->internal.subtree_offset != 0); 466 cursor->left_bound = &elm[0].internal.base; 467 cursor->right_bound = &elm[1].internal.base; 468 node = hammer_get_node(cursor->trans, 469 elm->internal.subtree_offset, 0, &error); 470 if (error == 0) { 471 KASSERT(elm->base.btype == node->ondisk->type, ("BTYPE MISMATCH %c %c NODE %p\n", elm->base.btype, node->ondisk->type, node)); 472 if (node->ondisk->parent != cursor->parent->node_offset) 473 panic("node %p %016llx vs %016llx\n", node, (long long)node->ondisk->parent, (long long)cursor->parent->node_offset); 474 KKASSERT(node->ondisk->parent == cursor->parent->node_offset); 475 } 476 break; 477 default: 478 panic("hammer_cursor_down: illegal btype %02x (%c)\n", 479 elm->base.btype, 480 (elm->base.btype ? elm->base.btype : '?')); 481 break; 482 } 483 if (error == 0) { 484 hammer_lock_sh(&node->lock); 485 KKASSERT ((node->flags & HAMMER_NODE_DELETED) == 0); 486 cursor->node = node; 487 cursor->index = 0; 488 } 489 return(error); 490 } 491 492 /************************************************************************ 493 * DEADLOCK RECOVERY * 494 ************************************************************************ 495 * 496 * These are the new deadlock recovery functions. Currently they are only 497 * used for the mirror propagation and physical node removal cases but 498 * ultimately the intention is to use them for all deadlock recovery 499 * operations. 500 * 501 * WARNING! The contents of the cursor may be modified while unlocked. 502 * passive modifications including adjusting the node, parent, 503 * indexes, and leaf pointer. 504 * 505 * An outright removal of the element the cursor was pointing at 506 * will cause the HAMMER_CURSOR_TRACKED_RIPOUT flag to be set, 507 * which chains to causing the HAMMER_CURSOR_RETEST to be set 508 * when the cursor is locked again. 509 */ 510 void 511 hammer_unlock_cursor(hammer_cursor_t cursor) 512 { 513 hammer_node_t node; 514 515 KKASSERT((cursor->flags & HAMMER_CURSOR_TRACKED) == 0); 516 KKASSERT(cursor->node); 517 518 /* 519 * Release the cursor's locks and track B-Tree operations on node. 520 * While being tracked our cursor can be modified by other threads 521 * and the node may be replaced. 522 */ 523 if (cursor->parent) { 524 hammer_unlock(&cursor->parent->lock); 525 hammer_rel_node(cursor->parent); 526 cursor->parent = NULL; 527 } 528 node = cursor->node; 529 cursor->flags |= HAMMER_CURSOR_TRACKED; 530 TAILQ_INSERT_TAIL(&node->cursor_list, cursor, deadlk_entry); 531 hammer_unlock(&node->lock); 532 } 533 534 /* 535 * Get the cursor heated up again. The cursor's node may have 536 * changed and we might have to locate the new parent. 537 * 538 * If the exact element we were on got deleted RIPOUT will be 539 * set and we must clear ATEDISK so an iteration does not skip 540 * the element after it. 541 */ 542 int 543 hammer_lock_cursor(hammer_cursor_t cursor) 544 { 545 hammer_node_t node; 546 int error; 547 548 KKASSERT(cursor->flags & HAMMER_CURSOR_TRACKED); 549 550 /* 551 * Relock the node 552 */ 553 for (;;) { 554 node = cursor->node; 555 hammer_ref_node(node); 556 hammer_lock_sh(&node->lock); 557 if (cursor->node == node) { 558 hammer_rel_node(node); 559 break; 560 } 561 hammer_unlock(&node->lock); 562 hammer_rel_node(node); 563 } 564 565 /* 566 * Untrack the cursor, clean up, and re-establish the parent node. 567 */ 568 TAILQ_REMOVE(&node->cursor_list, cursor, deadlk_entry); 569 cursor->flags &= ~HAMMER_CURSOR_TRACKED; 570 571 /* 572 * If a ripout has occured iterations must re-test the (new) 573 * current element. Clearing ATEDISK prevents the element from 574 * being skipped and RETEST causes it to be re-tested. 575 */ 576 if (cursor->flags & HAMMER_CURSOR_TRACKED_RIPOUT) { 577 cursor->flags &= ~HAMMER_CURSOR_TRACKED_RIPOUT; 578 cursor->flags &= ~HAMMER_CURSOR_ATEDISK; 579 cursor->flags |= HAMMER_CURSOR_RETEST; 580 } 581 error = hammer_load_cursor_parent(cursor, 0); 582 return(error); 583 } 584 585 /* 586 * Recover from a deadlocked cursor, tracking any node removals or 587 * replacements. If the cursor's current node is removed by another 588 * thread (via btree_remove()) the cursor will be seeked upwards. 589 * 590 * The caller is working a modifying operation and must be holding the 591 * sync lock (shared). We do not release the sync lock because this 592 * would break atomicy. 593 */ 594 int 595 hammer_recover_cursor(hammer_cursor_t cursor) 596 { 597 int error; 598 599 hammer_unlock_cursor(cursor); 600 KKASSERT(cursor->trans->sync_lock_refs > 0); 601 602 /* 603 * Wait for the deadlock to clear 604 */ 605 if (cursor->deadlk_node) { 606 hammer_lock_ex_ident(&cursor->deadlk_node->lock, "hmrdlk"); 607 hammer_unlock(&cursor->deadlk_node->lock); 608 hammer_rel_node(cursor->deadlk_node); 609 cursor->deadlk_node = NULL; 610 } 611 if (cursor->deadlk_rec) { 612 hammer_wait_mem_record_ident(cursor->deadlk_rec, "hmmdlr"); 613 hammer_rel_mem_record(cursor->deadlk_rec); 614 cursor->deadlk_rec = NULL; 615 } 616 error = hammer_lock_cursor(cursor); 617 return(error); 618 } 619 620 /* 621 * Dup ocursor to ncursor. ncursor inherits ocursor's locks and ocursor 622 * is effectively unlocked and becomes tracked. If ocursor was not locked 623 * then ncursor also inherits the tracking. 624 * 625 * After the caller finishes working with ncursor it must be cleaned up 626 * with hammer_done_cursor(), and the caller must re-lock ocursor. 627 */ 628 hammer_cursor_t 629 hammer_push_cursor(hammer_cursor_t ocursor) 630 { 631 hammer_cursor_t ncursor; 632 hammer_inode_t ip; 633 hammer_node_t node; 634 hammer_mount_t hmp; 635 636 hmp = ocursor->trans->hmp; 637 ncursor = kmalloc(sizeof(*ncursor), hmp->m_misc, M_WAITOK | M_ZERO); 638 bcopy(ocursor, ncursor, sizeof(*ocursor)); 639 640 node = ocursor->node; 641 hammer_ref_node(node); 642 if ((ocursor->flags & HAMMER_CURSOR_TRACKED) == 0) { 643 ocursor->flags |= HAMMER_CURSOR_TRACKED; 644 TAILQ_INSERT_TAIL(&node->cursor_list, ocursor, deadlk_entry); 645 } 646 if (ncursor->parent) 647 ocursor->parent = NULL; 648 ocursor->data_buffer = NULL; 649 ocursor->leaf = NULL; 650 ocursor->data = NULL; 651 if (ncursor->flags & HAMMER_CURSOR_TRACKED) 652 TAILQ_INSERT_TAIL(&node->cursor_list, ncursor, deadlk_entry); 653 if ((ip = ncursor->ip) != NULL) { 654 ++ip->cursor_ip_refs; 655 } 656 if (ncursor->iprec) 657 hammer_ref(&ncursor->iprec->lock); 658 return(ncursor); 659 } 660 661 /* 662 * Destroy ncursor and restore ocursor 663 * 664 * This is a temporary hack for the release. We can't afford to lose 665 * the IP lock until the IP object scan code is able to deal with it, 666 * so have ocursor inherit it back. 667 */ 668 void 669 hammer_pop_cursor(hammer_cursor_t ocursor, hammer_cursor_t ncursor) 670 { 671 hammer_mount_t hmp; 672 hammer_inode_t ip; 673 674 hmp = ncursor->trans->hmp; 675 ip = ncursor->ip; 676 ncursor->ip = NULL; 677 if (ip) 678 --ip->cursor_ip_refs; 679 hammer_done_cursor(ncursor); 680 kfree(ncursor, hmp->m_misc); 681 KKASSERT(ocursor->ip == ip); 682 hammer_lock_cursor(ocursor); 683 } 684 685 /* 686 * onode is being replaced by nnode by the reblocking code. 687 */ 688 void 689 hammer_cursor_replaced_node(hammer_node_t onode, hammer_node_t nnode) 690 { 691 hammer_cursor_t cursor; 692 hammer_node_ondisk_t ondisk; 693 hammer_node_ondisk_t nndisk; 694 695 ondisk = onode->ondisk; 696 nndisk = nnode->ondisk; 697 698 while ((cursor = TAILQ_FIRST(&onode->cursor_list)) != NULL) { 699 TAILQ_REMOVE(&onode->cursor_list, cursor, deadlk_entry); 700 TAILQ_INSERT_TAIL(&nnode->cursor_list, cursor, deadlk_entry); 701 KKASSERT(cursor->node == onode); 702 if (cursor->leaf == &ondisk->elms[cursor->index].leaf) 703 cursor->leaf = &nndisk->elms[cursor->index].leaf; 704 cursor->node = nnode; 705 hammer_ref_node(nnode); 706 hammer_rel_node(onode); 707 } 708 } 709 710 /* 711 * We have removed <node> from the parent and collapsed the parent. 712 * 713 * Cursors in deadlock recovery are seeked upward to the parent so the 714 * btree_remove() recursion works properly even though we have marked 715 * the cursor as requiring a reseek. 716 * 717 * This is the only cursor function which sets HAMMER_CURSOR_ITERATE_CHECK, 718 * meaning the cursor is no longer definitively pointing at an element 719 * within its iteration (if the cursor is being used to iterate). The 720 * iteration code will take this into account instead of asserting if the 721 * cursor is outside the iteration range. 722 */ 723 void 724 hammer_cursor_removed_node(hammer_node_t node, hammer_node_t parent, int index) 725 { 726 hammer_cursor_t cursor; 727 hammer_node_ondisk_t ondisk; 728 729 KKASSERT(parent != NULL); 730 ondisk = node->ondisk; 731 732 while ((cursor = TAILQ_FIRST(&node->cursor_list)) != NULL) { 733 KKASSERT(cursor->node == node); 734 KKASSERT(cursor->index == 0); 735 TAILQ_REMOVE(&node->cursor_list, cursor, deadlk_entry); 736 TAILQ_INSERT_TAIL(&parent->cursor_list, cursor, deadlk_entry); 737 if (cursor->leaf == &ondisk->elms[cursor->index].leaf) 738 cursor->leaf = NULL; 739 cursor->flags |= HAMMER_CURSOR_TRACKED_RIPOUT; 740 cursor->flags |= HAMMER_CURSOR_ITERATE_CHECK; 741 cursor->node = parent; 742 cursor->index = index; 743 hammer_ref_node(parent); 744 hammer_rel_node(node); 745 } 746 } 747 748 /* 749 * node was split at (onode, index) with elements >= index moved to nnode. 750 */ 751 void 752 hammer_cursor_split_node(hammer_node_t onode, hammer_node_t nnode, int index) 753 { 754 hammer_cursor_t cursor; 755 hammer_node_ondisk_t ondisk; 756 hammer_node_ondisk_t nndisk; 757 758 ondisk = onode->ondisk; 759 nndisk = nnode->ondisk; 760 761 again: 762 TAILQ_FOREACH(cursor, &onode->cursor_list, deadlk_entry) { 763 KKASSERT(cursor->node == onode); 764 if (cursor->index < index) 765 continue; 766 TAILQ_REMOVE(&onode->cursor_list, cursor, deadlk_entry); 767 TAILQ_INSERT_TAIL(&nnode->cursor_list, cursor, deadlk_entry); 768 if (cursor->leaf == &ondisk->elms[cursor->index].leaf) 769 cursor->leaf = &nndisk->elms[cursor->index - index].leaf; 770 cursor->node = nnode; 771 cursor->index -= index; 772 hammer_ref_node(nnode); 773 hammer_rel_node(onode); 774 goto again; 775 } 776 } 777 778 /* 779 * An element was moved from one node to another or within a node. The 780 * index may also represent the end of the node (index == numelements). 781 * 782 * {oparent,pindex} is the parent node's pointer to onode/oindex. 783 * 784 * This is used by the rebalancing code. This is not an insertion or 785 * deletion and any additional elements, including the degenerate case at 786 * the end of the node, will be dealt with by additional distinct calls. 787 */ 788 void 789 hammer_cursor_moved_element(hammer_node_t oparent, int pindex, 790 hammer_node_t onode, int oindex, 791 hammer_node_t nnode, int nindex) 792 { 793 hammer_cursor_t cursor; 794 hammer_node_ondisk_t ondisk; 795 hammer_node_ondisk_t nndisk; 796 797 /* 798 * Adjust any cursors pointing at the element 799 */ 800 ondisk = onode->ondisk; 801 nndisk = nnode->ondisk; 802 again1: 803 TAILQ_FOREACH(cursor, &onode->cursor_list, deadlk_entry) { 804 KKASSERT(cursor->node == onode); 805 if (cursor->index != oindex) 806 continue; 807 TAILQ_REMOVE(&onode->cursor_list, cursor, deadlk_entry); 808 TAILQ_INSERT_TAIL(&nnode->cursor_list, cursor, deadlk_entry); 809 if (cursor->leaf == &ondisk->elms[oindex].leaf) 810 cursor->leaf = &nndisk->elms[nindex].leaf; 811 cursor->node = nnode; 812 cursor->index = nindex; 813 hammer_ref_node(nnode); 814 hammer_rel_node(onode); 815 goto again1; 816 } 817 818 /* 819 * When moving the first element of onode to a different node any 820 * cursor which is pointing at (oparent,pindex) must be repointed 821 * to nnode and ATEDISK must be cleared. 822 * 823 * This prevents cursors from losing track due to insertions. 824 * Insertions temporarily release the cursor in order to update 825 * the mirror_tids. It primarily effects the mirror_write code. 826 * The other code paths generally only do a single insertion and 827 * then relookup or drop the cursor. 828 */ 829 if (onode == nnode || oindex) 830 return; 831 ondisk = oparent->ondisk; 832 again2: 833 TAILQ_FOREACH(cursor, &oparent->cursor_list, deadlk_entry) { 834 KKASSERT(cursor->node == oparent); 835 if (cursor->index != pindex) 836 continue; 837 kprintf("HAMMER debug: shifted cursor pointing at parent\n" 838 "parent %016jx:%d onode %016jx:%d nnode %016jx:%d\n", 839 (intmax_t)oparent->node_offset, pindex, 840 (intmax_t)onode->node_offset, oindex, 841 (intmax_t)nnode->node_offset, nindex); 842 TAILQ_REMOVE(&oparent->cursor_list, cursor, deadlk_entry); 843 TAILQ_INSERT_TAIL(&nnode->cursor_list, cursor, deadlk_entry); 844 if (cursor->leaf == &ondisk->elms[oindex].leaf) 845 cursor->leaf = &nndisk->elms[nindex].leaf; 846 cursor->node = nnode; 847 cursor->index = nindex; 848 cursor->flags &= ~HAMMER_CURSOR_ATEDISK; 849 hammer_ref_node(nnode); 850 hammer_rel_node(oparent); 851 goto again2; 852 } 853 } 854 855 /* 856 * The B-Tree element pointing to the specified node was moved from (oparent) 857 * to (nparent, nindex). We must locate any tracked cursors pointing at 858 * node and adjust their parent accordingly. 859 * 860 * This is used by the rebalancing code when packing elements causes an 861 * element to shift from one node to another. 862 */ 863 void 864 hammer_cursor_parent_changed(hammer_node_t node, hammer_node_t oparent, 865 hammer_node_t nparent, int nindex) 866 { 867 hammer_cursor_t cursor; 868 869 again: 870 TAILQ_FOREACH(cursor, &node->cursor_list, deadlk_entry) { 871 KKASSERT(cursor->node == node); 872 if (cursor->parent == oparent) { 873 cursor->parent = nparent; 874 cursor->parent_index = nindex; 875 hammer_ref_node(nparent); 876 hammer_rel_node(oparent); 877 goto again; 878 } 879 } 880 } 881 882 /* 883 * Deleted element at (node, index) 884 * 885 * Shift indexes >= index 886 */ 887 void 888 hammer_cursor_deleted_element(hammer_node_t node, int index) 889 { 890 hammer_cursor_t cursor; 891 hammer_node_ondisk_t ondisk; 892 893 ondisk = node->ondisk; 894 895 TAILQ_FOREACH(cursor, &node->cursor_list, deadlk_entry) { 896 KKASSERT(cursor->node == node); 897 if (cursor->index == index) { 898 cursor->flags |= HAMMER_CURSOR_TRACKED_RIPOUT; 899 if (cursor->leaf == &ondisk->elms[cursor->index].leaf) 900 cursor->leaf = NULL; 901 } else if (cursor->index > index) { 902 if (cursor->leaf == &ondisk->elms[cursor->index].leaf) 903 cursor->leaf = &ondisk->elms[cursor->index - 1].leaf; 904 --cursor->index; 905 } 906 } 907 } 908 909 /* 910 * Inserted element at (node, index) 911 * 912 * Shift indexes >= index 913 */ 914 void 915 hammer_cursor_inserted_element(hammer_node_t node, int index) 916 { 917 hammer_cursor_t cursor; 918 hammer_node_ondisk_t ondisk; 919 920 ondisk = node->ondisk; 921 922 TAILQ_FOREACH(cursor, &node->cursor_list, deadlk_entry) { 923 KKASSERT(cursor->node == node); 924 if (cursor->index >= index) { 925 if (cursor->leaf == &ondisk->elms[cursor->index].leaf) 926 cursor->leaf = &ondisk->elms[cursor->index + 1].leaf; 927 ++cursor->index; 928 } 929 } 930 } 931 932 /* 933 * Invalidate the cached data buffer associated with a cursor. 934 * 935 * This needs to be done when the underlying block is being freed or 936 * the referenced buffer can prevent the related buffer cache buffer 937 * from being properly invalidated. 938 */ 939 void 940 hammer_cursor_invalidate_cache(hammer_cursor_t cursor) 941 { 942 if (cursor->data_buffer) { 943 hammer_rel_buffer(cursor->data_buffer, 0); 944 cursor->data_buffer = NULL; 945 cursor->data = NULL; 946 } 947 } 948 949