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_btree.c,v 1.76 2008/08/06 15:38:58 dillon Exp $ 35 */ 36 37 /* 38 * HAMMER B-Tree index 39 * 40 * HAMMER implements a modified B+Tree. In documentation this will 41 * simply be refered to as the HAMMER B-Tree. Basically a HAMMER B-Tree 42 * looks like a B+Tree (A B-Tree which stores its records only at the leafs 43 * of the tree), but adds two additional boundary elements which describe 44 * the left-most and right-most element a node is able to represent. In 45 * otherwords, we have boundary elements at the two ends of a B-Tree node 46 * instead of sub-tree pointers. 47 * 48 * A B-Tree internal node looks like this: 49 * 50 * B N N N N N N B <-- boundary and internal elements 51 * S S S S S S S <-- subtree pointers 52 * 53 * A B-Tree leaf node basically looks like this: 54 * 55 * L L L L L L L L <-- leaf elemenets 56 * 57 * The radix for an internal node is 1 less then a leaf but we get a 58 * number of significant benefits for our troubles. 59 * 60 * The big benefit to using a B-Tree containing boundary information 61 * is that it is possible to cache pointers into the middle of the tree 62 * and not have to start searches, insertions, OR deletions at the root 63 * node. In particular, searches are able to progress in a definitive 64 * direction from any point in the tree without revisting nodes. This 65 * greatly improves the efficiency of many operations, most especially 66 * record appends. 67 * 68 * B-Trees also make the stacking of trees fairly straightforward. 69 * 70 * INSERTIONS: A search performed with the intention of doing 71 * an insert will guarantee that the terminal leaf node is not full by 72 * splitting full nodes. Splits occur top-down during the dive down the 73 * B-Tree. 74 * 75 * DELETIONS: A deletion makes no attempt to proactively balance the 76 * tree and will recursively remove nodes that become empty. If a 77 * deadlock occurs a deletion may not be able to remove an empty leaf. 78 * Deletions never allow internal nodes to become empty (that would blow 79 * up the boundaries). 80 */ 81 #include "hammer.h" 82 #include <sys/buf.h> 83 #include <sys/buf2.h> 84 85 static int btree_search(hammer_cursor_t cursor, int flags); 86 static int btree_split_internal(hammer_cursor_t cursor); 87 static int btree_split_leaf(hammer_cursor_t cursor); 88 static int btree_remove(hammer_cursor_t cursor); 89 static int btree_node_is_full(hammer_node_ondisk_t node); 90 static int hammer_btree_mirror_propagate(hammer_cursor_t cursor, 91 hammer_tid_t mirror_tid); 92 static void hammer_make_separator(hammer_base_elm_t key1, 93 hammer_base_elm_t key2, hammer_base_elm_t dest); 94 static void hammer_cursor_mirror_filter(hammer_cursor_t cursor); 95 96 /* 97 * Iterate records after a search. The cursor is iterated forwards past 98 * the current record until a record matching the key-range requirements 99 * is found. ENOENT is returned if the iteration goes past the ending 100 * key. 101 * 102 * The iteration is inclusive of key_beg and can be inclusive or exclusive 103 * of key_end depending on whether HAMMER_CURSOR_END_INCLUSIVE is set. 104 * 105 * When doing an as-of search (cursor->asof != 0), key_beg.create_tid 106 * may be modified by B-Tree functions. 107 * 108 * cursor->key_beg may or may not be modified by this function during 109 * the iteration. XXX future - in case of an inverted lock we may have 110 * to reinitiate the lookup and set key_beg to properly pick up where we 111 * left off. 112 * 113 * If HAMMER_CURSOR_ITERATE_CHECK is set it is possible that the cursor 114 * was reverse indexed due to being moved to a parent while unlocked, 115 * and something else might have inserted an element outside the iteration 116 * range. When this case occurs the iterator just keeps iterating until 117 * it gets back into the iteration range (instead of asserting). 118 * 119 * NOTE! EDEADLK *CANNOT* be returned by this procedure. 120 */ 121 int 122 hammer_btree_iterate(hammer_cursor_t cursor) 123 { 124 hammer_node_ondisk_t node; 125 hammer_btree_elm_t elm; 126 hammer_mount_t hmp; 127 int error = 0; 128 int r; 129 int s; 130 131 /* 132 * Skip past the current record 133 */ 134 hmp = cursor->trans->hmp; 135 node = cursor->node->ondisk; 136 if (node == NULL) 137 return(ENOENT); 138 if (cursor->index < node->count && 139 (cursor->flags & HAMMER_CURSOR_ATEDISK)) { 140 ++cursor->index; 141 } 142 143 /* 144 * HAMMER can wind up being cpu-bound. 145 */ 146 if (++hmp->check_yield > hammer_yield_check) { 147 hmp->check_yield = 0; 148 lwkt_user_yield(); 149 } 150 151 152 /* 153 * Loop until an element is found or we are done. 154 */ 155 for (;;) { 156 /* 157 * We iterate up the tree and then index over one element 158 * while we are at the last element in the current node. 159 * 160 * If we are at the root of the filesystem, cursor_up 161 * returns ENOENT. 162 * 163 * XXX this could be optimized by storing the information in 164 * the parent reference. 165 * 166 * XXX we can lose the node lock temporarily, this could mess 167 * up our scan. 168 */ 169 ++hammer_stats_btree_iterations; 170 hammer_flusher_clean_loose_ios(hmp); 171 172 if (cursor->index == node->count) { 173 if (hammer_debug_btree) { 174 kprintf("BRACKETU %016llx[%d] -> %016llx[%d] (td=%p)\n", 175 (long long)cursor->node->node_offset, 176 cursor->index, 177 (long long)(cursor->parent ? cursor->parent->node_offset : -1), 178 cursor->parent_index, 179 curthread); 180 } 181 KKASSERT(cursor->parent == NULL || cursor->parent->ondisk->elms[cursor->parent_index].internal.subtree_offset == cursor->node->node_offset); 182 error = hammer_cursor_up(cursor); 183 if (error) 184 break; 185 /* reload stale pointer */ 186 node = cursor->node->ondisk; 187 KKASSERT(cursor->index != node->count); 188 189 /* 190 * If we are reblocking we want to return internal 191 * nodes. Note that the internal node will be 192 * returned multiple times, on each upward recursion 193 * from its children. The caller selects which 194 * revisit it cares about (usually first or last only). 195 */ 196 if (cursor->flags & HAMMER_CURSOR_REBLOCKING) { 197 cursor->flags |= HAMMER_CURSOR_ATEDISK; 198 return(0); 199 } 200 ++cursor->index; 201 continue; 202 } 203 204 /* 205 * Check internal or leaf element. Determine if the record 206 * at the cursor has gone beyond the end of our range. 207 * 208 * We recurse down through internal nodes. 209 */ 210 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) { 211 elm = &node->elms[cursor->index]; 212 213 r = hammer_btree_cmp(&cursor->key_end, &elm[0].base); 214 s = hammer_btree_cmp(&cursor->key_beg, &elm[1].base); 215 if (hammer_debug_btree) { 216 kprintf("BRACKETL %016llx[%d] %016llx %02x %016llx lo=%02x %d (td=%p)\n", 217 (long long)cursor->node->node_offset, 218 cursor->index, 219 (long long)elm[0].internal.base.obj_id, 220 elm[0].internal.base.rec_type, 221 (long long)elm[0].internal.base.key, 222 elm[0].internal.base.localization, 223 r, 224 curthread 225 ); 226 kprintf("BRACKETR %016llx[%d] %016llx %02x %016llx lo=%02x %d\n", 227 (long long)cursor->node->node_offset, 228 cursor->index + 1, 229 (long long)elm[1].internal.base.obj_id, 230 elm[1].internal.base.rec_type, 231 (long long)elm[1].internal.base.key, 232 elm[1].internal.base.localization, 233 s 234 ); 235 } 236 237 if (r < 0) { 238 error = ENOENT; 239 break; 240 } 241 if (r == 0 && (cursor->flags & 242 HAMMER_CURSOR_END_INCLUSIVE) == 0) { 243 error = ENOENT; 244 break; 245 } 246 247 /* 248 * Better not be zero 249 */ 250 KKASSERT(elm->internal.subtree_offset != 0); 251 252 if (s <= 0) { 253 /* 254 * If running the mirror filter see if we 255 * can skip one or more entire sub-trees. 256 * If we can we return the internal node 257 * and the caller processes the skipped 258 * range (see mirror_read). 259 */ 260 if (cursor->flags & 261 HAMMER_CURSOR_MIRROR_FILTERED) { 262 if (elm->internal.mirror_tid < 263 cursor->cmirror->mirror_tid) { 264 hammer_cursor_mirror_filter(cursor); 265 return(0); 266 } 267 } 268 } else { 269 /* 270 * Normally it would be impossible for the 271 * cursor to have gotten back-indexed, 272 * but it can happen if a node is deleted 273 * and the cursor is moved to its parent 274 * internal node. ITERATE_CHECK will be set. 275 */ 276 KKASSERT(cursor->flags & 277 HAMMER_CURSOR_ITERATE_CHECK); 278 kprintf("hammer_btree_iterate: " 279 "DEBUG: Caught parent seek " 280 "in internal iteration\n"); 281 } 282 283 error = hammer_cursor_down(cursor); 284 if (error) 285 break; 286 KKASSERT(cursor->index == 0); 287 /* reload stale pointer */ 288 node = cursor->node->ondisk; 289 continue; 290 } else { 291 elm = &node->elms[cursor->index]; 292 r = hammer_btree_cmp(&cursor->key_end, &elm->base); 293 if (hammer_debug_btree) { 294 kprintf("ELEMENT %016llx:%d %c %016llx %02x %016llx lo=%02x %d\n", 295 (long long)cursor->node->node_offset, 296 cursor->index, 297 (elm[0].leaf.base.btype ? 298 elm[0].leaf.base.btype : '?'), 299 (long long)elm[0].leaf.base.obj_id, 300 elm[0].leaf.base.rec_type, 301 (long long)elm[0].leaf.base.key, 302 elm[0].leaf.base.localization, 303 r 304 ); 305 } 306 if (r < 0) { 307 error = ENOENT; 308 break; 309 } 310 311 /* 312 * We support both end-inclusive and 313 * end-exclusive searches. 314 */ 315 if (r == 0 && 316 (cursor->flags & HAMMER_CURSOR_END_INCLUSIVE) == 0) { 317 error = ENOENT; 318 break; 319 } 320 321 /* 322 * If ITERATE_CHECK is set an unlocked cursor may 323 * have been moved to a parent and the iterate can 324 * happen upon elements that are not in the requested 325 * range. 326 */ 327 if (cursor->flags & HAMMER_CURSOR_ITERATE_CHECK) { 328 s = hammer_btree_cmp(&cursor->key_beg, 329 &elm->base); 330 if (s > 0) { 331 kprintf("hammer_btree_iterate: " 332 "DEBUG: Caught parent seek " 333 "in leaf iteration\n"); 334 ++cursor->index; 335 continue; 336 } 337 } 338 cursor->flags &= ~HAMMER_CURSOR_ITERATE_CHECK; 339 340 /* 341 * Return the element 342 */ 343 switch(elm->leaf.base.btype) { 344 case HAMMER_BTREE_TYPE_RECORD: 345 if ((cursor->flags & HAMMER_CURSOR_ASOF) && 346 hammer_btree_chkts(cursor->asof, &elm->base)) { 347 ++cursor->index; 348 continue; 349 } 350 error = 0; 351 break; 352 default: 353 error = EINVAL; 354 break; 355 } 356 if (error) 357 break; 358 } 359 /* 360 * node pointer invalid after loop 361 */ 362 363 /* 364 * Return entry 365 */ 366 if (hammer_debug_btree) { 367 int i = cursor->index; 368 hammer_btree_elm_t elm = &cursor->node->ondisk->elms[i]; 369 kprintf("ITERATE %p:%d %016llx %02x %016llx lo=%02x\n", 370 cursor->node, i, 371 (long long)elm->internal.base.obj_id, 372 elm->internal.base.rec_type, 373 (long long)elm->internal.base.key, 374 elm->internal.base.localization 375 ); 376 } 377 return(0); 378 } 379 return(error); 380 } 381 382 /* 383 * We hit an internal element that we could skip as part of a mirroring 384 * scan. Calculate the entire range being skipped. 385 * 386 * It is important to include any gaps between the parent's left_bound 387 * and the node's left_bound, and same goes for the right side. 388 */ 389 static void 390 hammer_cursor_mirror_filter(hammer_cursor_t cursor) 391 { 392 struct hammer_cmirror *cmirror; 393 hammer_node_ondisk_t ondisk; 394 hammer_btree_elm_t elm; 395 396 ondisk = cursor->node->ondisk; 397 cmirror = cursor->cmirror; 398 399 /* 400 * Calculate the skipped range 401 */ 402 elm = &ondisk->elms[cursor->index]; 403 if (cursor->index == 0) 404 cmirror->skip_beg = *cursor->left_bound; 405 else 406 cmirror->skip_beg = elm->internal.base; 407 while (cursor->index < ondisk->count) { 408 if (elm->internal.mirror_tid >= cmirror->mirror_tid) 409 break; 410 ++cursor->index; 411 ++elm; 412 } 413 if (cursor->index == ondisk->count) 414 cmirror->skip_end = *cursor->right_bound; 415 else 416 cmirror->skip_end = elm->internal.base; 417 418 /* 419 * clip the returned result. 420 */ 421 if (hammer_btree_cmp(&cmirror->skip_beg, &cursor->key_beg) < 0) 422 cmirror->skip_beg = cursor->key_beg; 423 if (hammer_btree_cmp(&cmirror->skip_end, &cursor->key_end) > 0) 424 cmirror->skip_end = cursor->key_end; 425 } 426 427 /* 428 * Iterate in the reverse direction. This is used by the pruning code to 429 * avoid overlapping records. 430 */ 431 int 432 hammer_btree_iterate_reverse(hammer_cursor_t cursor) 433 { 434 hammer_node_ondisk_t node; 435 hammer_btree_elm_t elm; 436 hammer_mount_t hmp; 437 int error = 0; 438 int r; 439 int s; 440 441 /* mirror filtering not supported for reverse iteration */ 442 KKASSERT ((cursor->flags & HAMMER_CURSOR_MIRROR_FILTERED) == 0); 443 444 /* 445 * Skip past the current record. For various reasons the cursor 446 * may end up set to -1 or set to point at the end of the current 447 * node. These cases must be addressed. 448 */ 449 node = cursor->node->ondisk; 450 if (node == NULL) 451 return(ENOENT); 452 if (cursor->index != -1 && 453 (cursor->flags & HAMMER_CURSOR_ATEDISK)) { 454 --cursor->index; 455 } 456 if (cursor->index == cursor->node->ondisk->count) 457 --cursor->index; 458 459 /* 460 * HAMMER can wind up being cpu-bound. 461 */ 462 hmp = cursor->trans->hmp; 463 if (++hmp->check_yield > hammer_yield_check) { 464 hmp->check_yield = 0; 465 lwkt_user_yield(); 466 } 467 468 /* 469 * Loop until an element is found or we are done. 470 */ 471 for (;;) { 472 ++hammer_stats_btree_iterations; 473 hammer_flusher_clean_loose_ios(hmp); 474 475 /* 476 * We iterate up the tree and then index over one element 477 * while we are at the last element in the current node. 478 */ 479 if (cursor->index == -1) { 480 error = hammer_cursor_up(cursor); 481 if (error) { 482 cursor->index = 0; /* sanity */ 483 break; 484 } 485 /* reload stale pointer */ 486 node = cursor->node->ondisk; 487 KKASSERT(cursor->index != node->count); 488 --cursor->index; 489 continue; 490 } 491 492 /* 493 * Check internal or leaf element. Determine if the record 494 * at the cursor has gone beyond the end of our range. 495 * 496 * We recurse down through internal nodes. 497 */ 498 KKASSERT(cursor->index != node->count); 499 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) { 500 elm = &node->elms[cursor->index]; 501 r = hammer_btree_cmp(&cursor->key_end, &elm[0].base); 502 s = hammer_btree_cmp(&cursor->key_beg, &elm[1].base); 503 if (hammer_debug_btree) { 504 kprintf("BRACKETL %016llx[%d] %016llx %02x %016llx lo=%02x %d\n", 505 (long long)cursor->node->node_offset, 506 cursor->index, 507 (long long)elm[0].internal.base.obj_id, 508 elm[0].internal.base.rec_type, 509 (long long)elm[0].internal.base.key, 510 elm[0].internal.base.localization, 511 r 512 ); 513 kprintf("BRACKETR %016llx[%d] %016llx %02x %016llx lo=%02x %d\n", 514 (long long)cursor->node->node_offset, 515 cursor->index + 1, 516 (long long)elm[1].internal.base.obj_id, 517 elm[1].internal.base.rec_type, 518 (long long)elm[1].internal.base.key, 519 elm[1].internal.base.localization, 520 s 521 ); 522 } 523 524 if (s >= 0) { 525 error = ENOENT; 526 break; 527 } 528 529 /* 530 * It shouldn't be possible to be seeked past key_end, 531 * even if the cursor got moved to a parent. 532 */ 533 KKASSERT(r >= 0); 534 535 /* 536 * Better not be zero 537 */ 538 KKASSERT(elm->internal.subtree_offset != 0); 539 540 error = hammer_cursor_down(cursor); 541 if (error) 542 break; 543 KKASSERT(cursor->index == 0); 544 /* reload stale pointer */ 545 node = cursor->node->ondisk; 546 547 /* this can assign -1 if the leaf was empty */ 548 cursor->index = node->count - 1; 549 continue; 550 } else { 551 elm = &node->elms[cursor->index]; 552 s = hammer_btree_cmp(&cursor->key_beg, &elm->base); 553 if (hammer_debug_btree) { 554 kprintf("ELEMENT %016llx:%d %c %016llx %02x %016llx lo=%02x %d\n", 555 (long long)cursor->node->node_offset, 556 cursor->index, 557 (elm[0].leaf.base.btype ? 558 elm[0].leaf.base.btype : '?'), 559 (long long)elm[0].leaf.base.obj_id, 560 elm[0].leaf.base.rec_type, 561 (long long)elm[0].leaf.base.key, 562 elm[0].leaf.base.localization, 563 s 564 ); 565 } 566 if (s > 0) { 567 error = ENOENT; 568 break; 569 } 570 571 /* 572 * It shouldn't be possible to be seeked past key_end, 573 * even if the cursor got moved to a parent. 574 */ 575 cursor->flags &= ~HAMMER_CURSOR_ITERATE_CHECK; 576 577 /* 578 * Return the element 579 */ 580 switch(elm->leaf.base.btype) { 581 case HAMMER_BTREE_TYPE_RECORD: 582 if ((cursor->flags & HAMMER_CURSOR_ASOF) && 583 hammer_btree_chkts(cursor->asof, &elm->base)) { 584 --cursor->index; 585 continue; 586 } 587 error = 0; 588 break; 589 default: 590 error = EINVAL; 591 break; 592 } 593 if (error) 594 break; 595 } 596 /* 597 * node pointer invalid after loop 598 */ 599 600 /* 601 * Return entry 602 */ 603 if (hammer_debug_btree) { 604 int i = cursor->index; 605 hammer_btree_elm_t elm = &cursor->node->ondisk->elms[i]; 606 kprintf("ITERATE %p:%d %016llx %02x %016llx lo=%02x\n", 607 cursor->node, i, 608 (long long)elm->internal.base.obj_id, 609 elm->internal.base.rec_type, 610 (long long)elm->internal.base.key, 611 elm->internal.base.localization 612 ); 613 } 614 return(0); 615 } 616 return(error); 617 } 618 619 /* 620 * Lookup cursor->key_beg. 0 is returned on success, ENOENT if the entry 621 * could not be found, EDEADLK if inserting and a retry is needed, and a 622 * fatal error otherwise. When retrying, the caller must terminate the 623 * cursor and reinitialize it. EDEADLK cannot be returned if not inserting. 624 * 625 * The cursor is suitably positioned for a deletion on success, and suitably 626 * positioned for an insertion on ENOENT if HAMMER_CURSOR_INSERT was 627 * specified. 628 * 629 * The cursor may begin anywhere, the search will traverse the tree in 630 * either direction to locate the requested element. 631 * 632 * Most of the logic implementing historical searches is handled here. We 633 * do an initial lookup with create_tid set to the asof TID. Due to the 634 * way records are laid out, a backwards iteration may be required if 635 * ENOENT is returned to locate the historical record. Here's the 636 * problem: 637 * 638 * create_tid: 10 15 20 639 * LEAF1 LEAF2 640 * records: (11) (18) 641 * 642 * Lets say we want to do a lookup AS-OF timestamp 17. We will traverse 643 * LEAF2 but the only record in LEAF2 has a create_tid of 18, which is 644 * not visible and thus causes ENOENT to be returned. We really need 645 * to check record 11 in LEAF1. If it also fails then the search fails 646 * (e.g. it might represent the range 11-16 and thus still not match our 647 * AS-OF timestamp of 17). Note that LEAF1 could be empty, requiring 648 * further iterations. 649 * 650 * If this case occurs btree_search() will set HAMMER_CURSOR_CREATE_CHECK 651 * and the cursor->create_check TID if an iteration might be needed. 652 * In the above example create_check would be set to 14. 653 */ 654 int 655 hammer_btree_lookup(hammer_cursor_t cursor) 656 { 657 int error; 658 659 cursor->flags &= ~HAMMER_CURSOR_ITERATE_CHECK; 660 KKASSERT ((cursor->flags & HAMMER_CURSOR_INSERT) == 0 || 661 cursor->trans->sync_lock_refs > 0); 662 ++hammer_stats_btree_lookups; 663 if (cursor->flags & HAMMER_CURSOR_ASOF) { 664 KKASSERT((cursor->flags & HAMMER_CURSOR_INSERT) == 0); 665 cursor->key_beg.create_tid = cursor->asof; 666 for (;;) { 667 cursor->flags &= ~HAMMER_CURSOR_CREATE_CHECK; 668 error = btree_search(cursor, 0); 669 if (error != ENOENT || 670 (cursor->flags & HAMMER_CURSOR_CREATE_CHECK) == 0) { 671 /* 672 * Stop if no error. 673 * Stop if error other then ENOENT. 674 * Stop if ENOENT and not special case. 675 */ 676 break; 677 } 678 if (hammer_debug_btree) { 679 kprintf("CREATE_CHECK %016llx\n", 680 (long long)cursor->create_check); 681 } 682 cursor->key_beg.create_tid = cursor->create_check; 683 /* loop */ 684 } 685 } else { 686 error = btree_search(cursor, 0); 687 } 688 if (error == 0) 689 error = hammer_btree_extract(cursor, cursor->flags); 690 return(error); 691 } 692 693 /* 694 * Execute the logic required to start an iteration. The first record 695 * located within the specified range is returned and iteration control 696 * flags are adjusted for successive hammer_btree_iterate() calls. 697 * 698 * Set ATEDISK so a low-level caller can call btree_first/btree_iterate 699 * in a loop without worrying about it. Higher-level merged searches will 700 * adjust the flag appropriately. 701 */ 702 int 703 hammer_btree_first(hammer_cursor_t cursor) 704 { 705 int error; 706 707 error = hammer_btree_lookup(cursor); 708 if (error == ENOENT) { 709 cursor->flags &= ~HAMMER_CURSOR_ATEDISK; 710 error = hammer_btree_iterate(cursor); 711 } 712 cursor->flags |= HAMMER_CURSOR_ATEDISK; 713 return(error); 714 } 715 716 /* 717 * Similarly but for an iteration in the reverse direction. 718 * 719 * Set ATEDISK when iterating backwards to skip the current entry, 720 * which after an ENOENT lookup will be pointing beyond our end point. 721 * 722 * Set ATEDISK so a low-level caller can call btree_last/btree_iterate_reverse 723 * in a loop without worrying about it. Higher-level merged searches will 724 * adjust the flag appropriately. 725 */ 726 int 727 hammer_btree_last(hammer_cursor_t cursor) 728 { 729 struct hammer_base_elm save; 730 int error; 731 732 save = cursor->key_beg; 733 cursor->key_beg = cursor->key_end; 734 error = hammer_btree_lookup(cursor); 735 cursor->key_beg = save; 736 if (error == ENOENT || 737 (cursor->flags & HAMMER_CURSOR_END_INCLUSIVE) == 0) { 738 cursor->flags |= HAMMER_CURSOR_ATEDISK; 739 error = hammer_btree_iterate_reverse(cursor); 740 } 741 cursor->flags |= HAMMER_CURSOR_ATEDISK; 742 return(error); 743 } 744 745 /* 746 * Extract the record and/or data associated with the cursor's current 747 * position. Any prior record or data stored in the cursor is replaced. 748 * The cursor must be positioned at a leaf node. 749 * 750 * NOTE: All extractions occur at the leaf of the B-Tree. 751 */ 752 int 753 hammer_btree_extract(hammer_cursor_t cursor, int flags) 754 { 755 hammer_node_ondisk_t node; 756 hammer_btree_elm_t elm; 757 hammer_off_t data_off; 758 hammer_mount_t hmp; 759 int32_t data_len; 760 int error; 761 762 /* 763 * The case where the data reference resolves to the same buffer 764 * as the record reference must be handled. 765 */ 766 node = cursor->node->ondisk; 767 elm = &node->elms[cursor->index]; 768 cursor->data = NULL; 769 hmp = cursor->node->hmp; 770 771 /* 772 * There is nothing to extract for an internal element. 773 */ 774 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) 775 return(EINVAL); 776 777 /* 778 * Only record types have data. 779 */ 780 KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF); 781 cursor->leaf = &elm->leaf; 782 783 if ((flags & HAMMER_CURSOR_GET_DATA) == 0) 784 return(0); 785 if (elm->leaf.base.btype != HAMMER_BTREE_TYPE_RECORD) 786 return(0); 787 data_off = elm->leaf.data_offset; 788 data_len = elm->leaf.data_len; 789 if (data_off == 0) 790 return(0); 791 792 /* 793 * Load the data 794 */ 795 KKASSERT(data_len >= 0 && data_len <= HAMMER_XBUFSIZE); 796 cursor->data = hammer_bread_ext(hmp, data_off, data_len, 797 &error, &cursor->data_buffer); 798 799 /* 800 * Mark the data buffer as not being meta-data if it isn't 801 * meta-data (sometimes bulk data is accessed via a volume 802 * block device). 803 */ 804 if (error == 0) { 805 switch(elm->leaf.base.rec_type) { 806 case HAMMER_RECTYPE_DATA: 807 case HAMMER_RECTYPE_DB: 808 if ((data_off & HAMMER_ZONE_LARGE_DATA) == 0) 809 break; 810 if (hammer_double_buffer == 0 || 811 (cursor->flags & HAMMER_CURSOR_NOSWAPCACHE)) { 812 hammer_io_notmeta(cursor->data_buffer); 813 } 814 break; 815 default: 816 break; 817 } 818 } 819 820 /* 821 * Deal with CRC errors on the extracted data. 822 */ 823 if (error == 0 && 824 hammer_crc_test_leaf(cursor->data, &elm->leaf) == 0) { 825 kprintf("CRC DATA @ %016llx/%d FAILED\n", 826 (long long)elm->leaf.data_offset, elm->leaf.data_len); 827 if (hammer_debug_critical) 828 Debugger("CRC FAILED: DATA"); 829 if (cursor->trans->flags & HAMMER_TRANSF_CRCDOM) 830 error = EDOM; /* less critical (mirroring) */ 831 else 832 error = EIO; /* critical */ 833 } 834 return(error); 835 } 836 837 838 /* 839 * Insert a leaf element into the B-Tree at the current cursor position. 840 * The cursor is positioned such that the element at and beyond the cursor 841 * are shifted to make room for the new record. 842 * 843 * The caller must call hammer_btree_lookup() with the HAMMER_CURSOR_INSERT 844 * flag set and that call must return ENOENT before this function can be 845 * called. 846 * 847 * The caller may depend on the cursor's exclusive lock after return to 848 * interlock frontend visibility (see HAMMER_RECF_CONVERT_DELETE). 849 * 850 * ENOSPC is returned if there is no room to insert a new record. 851 */ 852 int 853 hammer_btree_insert(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm, 854 int *doprop) 855 { 856 hammer_node_ondisk_t node; 857 int i; 858 int error; 859 860 *doprop = 0; 861 if ((error = hammer_cursor_upgrade_node(cursor)) != 0) 862 return(error); 863 ++hammer_stats_btree_inserts; 864 865 /* 866 * Insert the element at the leaf node and update the count in the 867 * parent. It is possible for parent to be NULL, indicating that 868 * the filesystem's ROOT B-Tree node is a leaf itself, which is 869 * possible. The root inode can never be deleted so the leaf should 870 * never be empty. 871 * 872 * Remember that the right-hand boundary is not included in the 873 * count. 874 */ 875 hammer_modify_node_all(cursor->trans, cursor->node); 876 node = cursor->node->ondisk; 877 i = cursor->index; 878 KKASSERT(elm->base.btype != 0); 879 KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF); 880 KKASSERT(node->count < HAMMER_BTREE_LEAF_ELMS); 881 if (i != node->count) { 882 bcopy(&node->elms[i], &node->elms[i+1], 883 (node->count - i) * sizeof(*elm)); 884 } 885 node->elms[i].leaf = *elm; 886 ++node->count; 887 hammer_cursor_inserted_element(cursor->node, i); 888 889 /* 890 * Update the leaf node's aggregate mirror_tid for mirroring 891 * support. 892 */ 893 if (node->mirror_tid < elm->base.delete_tid) { 894 node->mirror_tid = elm->base.delete_tid; 895 *doprop = 1; 896 } 897 if (node->mirror_tid < elm->base.create_tid) { 898 node->mirror_tid = elm->base.create_tid; 899 *doprop = 1; 900 } 901 hammer_modify_node_done(cursor->node); 902 903 /* 904 * Debugging sanity checks. 905 */ 906 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->base) <= 0); 907 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->base) > 0); 908 if (i) { 909 KKASSERT(hammer_btree_cmp(&node->elms[i-1].leaf.base, &elm->base) < 0); 910 } 911 if (i != node->count - 1) 912 KKASSERT(hammer_btree_cmp(&node->elms[i+1].leaf.base, &elm->base) > 0); 913 914 return(0); 915 } 916 917 /* 918 * Delete a record from the B-Tree at the current cursor position. 919 * The cursor is positioned such that the current element is the one 920 * to be deleted. 921 * 922 * On return the cursor will be positioned after the deleted element and 923 * MAY point to an internal node. It will be suitable for the continuation 924 * of an iteration but not for an insertion or deletion. 925 * 926 * Deletions will attempt to partially rebalance the B-Tree in an upward 927 * direction, but will terminate rather then deadlock. Empty internal nodes 928 * are never allowed by a deletion which deadlocks may end up giving us an 929 * empty leaf. The pruner will clean up and rebalance the tree. 930 * 931 * This function can return EDEADLK, requiring the caller to retry the 932 * operation after clearing the deadlock. 933 */ 934 int 935 hammer_btree_delete(hammer_cursor_t cursor) 936 { 937 hammer_node_ondisk_t ondisk; 938 hammer_node_t node; 939 hammer_node_t parent; 940 int error; 941 int i; 942 943 KKASSERT (cursor->trans->sync_lock_refs > 0); 944 if ((error = hammer_cursor_upgrade(cursor)) != 0) 945 return(error); 946 ++hammer_stats_btree_deletes; 947 948 /* 949 * Delete the element from the leaf node. 950 * 951 * Remember that leaf nodes do not have boundaries. 952 */ 953 node = cursor->node; 954 ondisk = node->ondisk; 955 i = cursor->index; 956 957 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_LEAF); 958 KKASSERT(i >= 0 && i < ondisk->count); 959 hammer_modify_node_all(cursor->trans, node); 960 if (i + 1 != ondisk->count) { 961 bcopy(&ondisk->elms[i+1], &ondisk->elms[i], 962 (ondisk->count - i - 1) * sizeof(ondisk->elms[0])); 963 } 964 --ondisk->count; 965 hammer_modify_node_done(node); 966 hammer_cursor_deleted_element(node, i); 967 968 /* 969 * Validate local parent 970 */ 971 if (ondisk->parent) { 972 parent = cursor->parent; 973 974 KKASSERT(parent != NULL); 975 KKASSERT(parent->node_offset == ondisk->parent); 976 } 977 978 /* 979 * If the leaf becomes empty it must be detached from the parent, 980 * potentially recursing through to the filesystem root. 981 * 982 * This may reposition the cursor at one of the parent's of the 983 * current node. 984 * 985 * Ignore deadlock errors, that simply means that btree_remove 986 * was unable to recurse and had to leave us with an empty leaf. 987 */ 988 KKASSERT(cursor->index <= ondisk->count); 989 if (ondisk->count == 0) { 990 error = btree_remove(cursor); 991 if (error == EDEADLK) 992 error = 0; 993 } else { 994 error = 0; 995 } 996 KKASSERT(cursor->parent == NULL || 997 cursor->parent_index < cursor->parent->ondisk->count); 998 return(error); 999 } 1000 1001 /* 1002 * PRIMAY B-TREE SEARCH SUPPORT PROCEDURE 1003 * 1004 * Search the filesystem B-Tree for cursor->key_beg, return the matching node. 1005 * 1006 * The search can begin ANYWHERE in the B-Tree. As a first step the search 1007 * iterates up the tree as necessary to properly position itself prior to 1008 * actually doing the sarch. 1009 * 1010 * INSERTIONS: The search will split full nodes and leaves on its way down 1011 * and guarentee that the leaf it ends up on is not full. If we run out 1012 * of space the search continues to the leaf (to position the cursor for 1013 * the spike), but ENOSPC is returned. 1014 * 1015 * The search is only guarenteed to end up on a leaf if an error code of 0 1016 * is returned, or if inserting and an error code of ENOENT is returned. 1017 * Otherwise it can stop at an internal node. On success a search returns 1018 * a leaf node. 1019 * 1020 * COMPLEXITY WARNING! This is the core B-Tree search code for the entire 1021 * filesystem, and it is not simple code. Please note the following facts: 1022 * 1023 * - Internal node recursions have a boundary on the left AND right. The 1024 * right boundary is non-inclusive. The create_tid is a generic part 1025 * of the key for internal nodes. 1026 * 1027 * - Leaf nodes contain terminal elements only now. 1028 * 1029 * - Filesystem lookups typically set HAMMER_CURSOR_ASOF, indicating a 1030 * historical search. ASOF and INSERT are mutually exclusive. When 1031 * doing an as-of lookup btree_search() checks for a right-edge boundary 1032 * case. If while recursing down the left-edge differs from the key 1033 * by ONLY its create_tid, HAMMER_CURSOR_CREATE_CHECK is set along 1034 * with cursor->create_check. This is used by btree_lookup() to iterate. 1035 * The iteration backwards because as-of searches can wind up going 1036 * down the wrong branch of the B-Tree. 1037 */ 1038 static 1039 int 1040 btree_search(hammer_cursor_t cursor, int flags) 1041 { 1042 hammer_node_ondisk_t node; 1043 hammer_btree_elm_t elm; 1044 int error; 1045 int enospc = 0; 1046 int i; 1047 int r; 1048 int s; 1049 1050 flags |= cursor->flags; 1051 ++hammer_stats_btree_searches; 1052 1053 if (hammer_debug_btree) { 1054 kprintf("SEARCH %016llx[%d] %016llx %02x key=%016llx cre=%016llx lo=%02x (td = %p)\n", 1055 (long long)cursor->node->node_offset, 1056 cursor->index, 1057 (long long)cursor->key_beg.obj_id, 1058 cursor->key_beg.rec_type, 1059 (long long)cursor->key_beg.key, 1060 (long long)cursor->key_beg.create_tid, 1061 cursor->key_beg.localization, 1062 curthread 1063 ); 1064 if (cursor->parent) 1065 kprintf("SEARCHP %016llx[%d] (%016llx/%016llx %016llx/%016llx) (%p/%p %p/%p)\n", 1066 (long long)cursor->parent->node_offset, 1067 cursor->parent_index, 1068 (long long)cursor->left_bound->obj_id, 1069 (long long)cursor->parent->ondisk->elms[cursor->parent_index].internal.base.obj_id, 1070 (long long)cursor->right_bound->obj_id, 1071 (long long)cursor->parent->ondisk->elms[cursor->parent_index+1].internal.base.obj_id, 1072 cursor->left_bound, 1073 &cursor->parent->ondisk->elms[cursor->parent_index], 1074 cursor->right_bound, 1075 &cursor->parent->ondisk->elms[cursor->parent_index+1] 1076 ); 1077 } 1078 1079 /* 1080 * Move our cursor up the tree until we find a node whos range covers 1081 * the key we are trying to locate. 1082 * 1083 * The left bound is inclusive, the right bound is non-inclusive. 1084 * It is ok to cursor up too far. 1085 */ 1086 for (;;) { 1087 r = hammer_btree_cmp(&cursor->key_beg, cursor->left_bound); 1088 s = hammer_btree_cmp(&cursor->key_beg, cursor->right_bound); 1089 if (r >= 0 && s < 0) 1090 break; 1091 KKASSERT(cursor->parent); 1092 ++hammer_stats_btree_iterations; 1093 error = hammer_cursor_up(cursor); 1094 if (error) 1095 goto done; 1096 } 1097 1098 /* 1099 * The delete-checks below are based on node, not parent. Set the 1100 * initial delete-check based on the parent. 1101 */ 1102 if (r == 1) { 1103 KKASSERT(cursor->left_bound->create_tid != 1); 1104 cursor->create_check = cursor->left_bound->create_tid - 1; 1105 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK; 1106 } 1107 1108 /* 1109 * We better have ended up with a node somewhere. 1110 */ 1111 KKASSERT(cursor->node != NULL); 1112 1113 /* 1114 * If we are inserting we can't start at a full node if the parent 1115 * is also full (because there is no way to split the node), 1116 * continue running up the tree until the requirement is satisfied 1117 * or we hit the root of the filesystem. 1118 * 1119 * (If inserting we aren't doing an as-of search so we don't have 1120 * to worry about create_check). 1121 */ 1122 while ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) { 1123 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 1124 if (btree_node_is_full(cursor->node->ondisk) == 0) 1125 break; 1126 } else { 1127 if (btree_node_is_full(cursor->node->ondisk) ==0) 1128 break; 1129 } 1130 if (cursor->node->ondisk->parent == 0 || 1131 cursor->parent->ondisk->count != HAMMER_BTREE_INT_ELMS) { 1132 break; 1133 } 1134 ++hammer_stats_btree_iterations; 1135 error = hammer_cursor_up(cursor); 1136 /* node may have become stale */ 1137 if (error) 1138 goto done; 1139 } 1140 1141 /* 1142 * Push down through internal nodes to locate the requested key. 1143 */ 1144 node = cursor->node->ondisk; 1145 while (node->type == HAMMER_BTREE_TYPE_INTERNAL) { 1146 /* 1147 * Scan the node to find the subtree index to push down into. 1148 * We go one-past, then back-up. 1149 * 1150 * We must proactively remove deleted elements which may 1151 * have been left over from a deadlocked btree_remove(). 1152 * 1153 * The left and right boundaries are included in the loop 1154 * in order to detect edge cases. 1155 * 1156 * If the separator only differs by create_tid (r == 1) 1157 * and we are doing an as-of search, we may end up going 1158 * down a branch to the left of the one containing the 1159 * desired key. This requires numerous special cases. 1160 */ 1161 ++hammer_stats_btree_iterations; 1162 if (hammer_debug_btree) { 1163 kprintf("SEARCH-I %016llx count=%d\n", 1164 (long long)cursor->node->node_offset, 1165 node->count); 1166 } 1167 1168 /* 1169 * Try to shortcut the search before dropping into the 1170 * linear loop. Locate the first node where r <= 1. 1171 */ 1172 i = hammer_btree_search_node(&cursor->key_beg, node); 1173 while (i <= node->count) { 1174 ++hammer_stats_btree_elements; 1175 elm = &node->elms[i]; 1176 r = hammer_btree_cmp(&cursor->key_beg, &elm->base); 1177 if (hammer_debug_btree > 2) { 1178 kprintf(" IELM %p %d r=%d\n", 1179 &node->elms[i], i, r); 1180 } 1181 if (r < 0) 1182 break; 1183 if (r == 1) { 1184 KKASSERT(elm->base.create_tid != 1); 1185 cursor->create_check = elm->base.create_tid - 1; 1186 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK; 1187 } 1188 ++i; 1189 } 1190 if (hammer_debug_btree) { 1191 kprintf("SEARCH-I preI=%d/%d r=%d\n", 1192 i, node->count, r); 1193 } 1194 1195 /* 1196 * These cases occur when the parent's idea of the boundary 1197 * is wider then the child's idea of the boundary, and 1198 * require special handling. If not inserting we can 1199 * terminate the search early for these cases but the 1200 * child's boundaries cannot be unconditionally modified. 1201 */ 1202 if (i == 0) { 1203 /* 1204 * If i == 0 the search terminated to the LEFT of the 1205 * left_boundary but to the RIGHT of the parent's left 1206 * boundary. 1207 */ 1208 u_int8_t save; 1209 1210 elm = &node->elms[0]; 1211 1212 /* 1213 * If we aren't inserting we can stop here. 1214 */ 1215 if ((flags & (HAMMER_CURSOR_INSERT | 1216 HAMMER_CURSOR_PRUNING)) == 0) { 1217 cursor->index = 0; 1218 return(ENOENT); 1219 } 1220 1221 /* 1222 * Correct a left-hand boundary mismatch. 1223 * 1224 * We can only do this if we can upgrade the lock, 1225 * and synchronized as a background cursor (i.e. 1226 * inserting or pruning). 1227 * 1228 * WARNING: We can only do this if inserting, i.e. 1229 * we are running on the backend. 1230 */ 1231 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1232 return(error); 1233 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND); 1234 hammer_modify_node_field(cursor->trans, cursor->node, 1235 elms[0]); 1236 save = node->elms[0].base.btype; 1237 node->elms[0].base = *cursor->left_bound; 1238 node->elms[0].base.btype = save; 1239 hammer_modify_node_done(cursor->node); 1240 } else if (i == node->count + 1) { 1241 /* 1242 * If i == node->count + 1 the search terminated to 1243 * the RIGHT of the right boundary but to the LEFT 1244 * of the parent's right boundary. If we aren't 1245 * inserting we can stop here. 1246 * 1247 * Note that the last element in this case is 1248 * elms[i-2] prior to adjustments to 'i'. 1249 */ 1250 --i; 1251 if ((flags & (HAMMER_CURSOR_INSERT | 1252 HAMMER_CURSOR_PRUNING)) == 0) { 1253 cursor->index = i; 1254 return (ENOENT); 1255 } 1256 1257 /* 1258 * Correct a right-hand boundary mismatch. 1259 * (actual push-down record is i-2 prior to 1260 * adjustments to i). 1261 * 1262 * We can only do this if we can upgrade the lock, 1263 * and synchronized as a background cursor (i.e. 1264 * inserting or pruning). 1265 * 1266 * WARNING: We can only do this if inserting, i.e. 1267 * we are running on the backend. 1268 */ 1269 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1270 return(error); 1271 elm = &node->elms[i]; 1272 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND); 1273 hammer_modify_node(cursor->trans, cursor->node, 1274 &elm->base, sizeof(elm->base)); 1275 elm->base = *cursor->right_bound; 1276 hammer_modify_node_done(cursor->node); 1277 --i; 1278 } else { 1279 /* 1280 * The push-down index is now i - 1. If we had 1281 * terminated on the right boundary this will point 1282 * us at the last element. 1283 */ 1284 --i; 1285 } 1286 cursor->index = i; 1287 elm = &node->elms[i]; 1288 1289 if (hammer_debug_btree) { 1290 kprintf("RESULT-I %016llx[%d] %016llx %02x " 1291 "key=%016llx cre=%016llx lo=%02x\n", 1292 (long long)cursor->node->node_offset, 1293 i, 1294 (long long)elm->internal.base.obj_id, 1295 elm->internal.base.rec_type, 1296 (long long)elm->internal.base.key, 1297 (long long)elm->internal.base.create_tid, 1298 elm->internal.base.localization 1299 ); 1300 } 1301 1302 /* 1303 * We better have a valid subtree offset. 1304 */ 1305 KKASSERT(elm->internal.subtree_offset != 0); 1306 1307 /* 1308 * Handle insertion and deletion requirements. 1309 * 1310 * If inserting split full nodes. The split code will 1311 * adjust cursor->node and cursor->index if the current 1312 * index winds up in the new node. 1313 * 1314 * If inserting and a left or right edge case was detected, 1315 * we cannot correct the left or right boundary and must 1316 * prepend and append an empty leaf node in order to make 1317 * the boundary correction. 1318 * 1319 * If we run out of space we set enospc and continue on 1320 * to a leaf to provide the spike code with a good point 1321 * of entry. 1322 */ 1323 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) { 1324 if (btree_node_is_full(node)) { 1325 error = btree_split_internal(cursor); 1326 if (error) { 1327 if (error != ENOSPC) 1328 goto done; 1329 enospc = 1; 1330 } 1331 /* 1332 * reload stale pointers 1333 */ 1334 i = cursor->index; 1335 node = cursor->node->ondisk; 1336 } 1337 } 1338 1339 /* 1340 * Push down (push into new node, existing node becomes 1341 * the parent) and continue the search. 1342 */ 1343 error = hammer_cursor_down(cursor); 1344 /* node may have become stale */ 1345 if (error) 1346 goto done; 1347 node = cursor->node->ondisk; 1348 } 1349 1350 /* 1351 * We are at a leaf, do a linear search of the key array. 1352 * 1353 * On success the index is set to the matching element and 0 1354 * is returned. 1355 * 1356 * On failure the index is set to the insertion point and ENOENT 1357 * is returned. 1358 * 1359 * Boundaries are not stored in leaf nodes, so the index can wind 1360 * up to the left of element 0 (index == 0) or past the end of 1361 * the array (index == node->count). It is also possible that the 1362 * leaf might be empty. 1363 */ 1364 ++hammer_stats_btree_iterations; 1365 KKASSERT (node->type == HAMMER_BTREE_TYPE_LEAF); 1366 KKASSERT(node->count <= HAMMER_BTREE_LEAF_ELMS); 1367 if (hammer_debug_btree) { 1368 kprintf("SEARCH-L %016llx count=%d\n", 1369 (long long)cursor->node->node_offset, 1370 node->count); 1371 } 1372 1373 /* 1374 * Try to shortcut the search before dropping into the 1375 * linear loop. Locate the first node where r <= 1. 1376 */ 1377 i = hammer_btree_search_node(&cursor->key_beg, node); 1378 while (i < node->count) { 1379 ++hammer_stats_btree_elements; 1380 elm = &node->elms[i]; 1381 1382 r = hammer_btree_cmp(&cursor->key_beg, &elm->leaf.base); 1383 1384 if (hammer_debug_btree > 1) 1385 kprintf(" ELM %p %d r=%d\n", &node->elms[i], i, r); 1386 1387 /* 1388 * We are at a record element. Stop if we've flipped past 1389 * key_beg, not counting the create_tid test. Allow the 1390 * r == 1 case (key_beg > element but differs only by its 1391 * create_tid) to fall through to the AS-OF check. 1392 */ 1393 KKASSERT (elm->leaf.base.btype == HAMMER_BTREE_TYPE_RECORD); 1394 1395 if (r < 0) 1396 goto failed; 1397 if (r > 1) { 1398 ++i; 1399 continue; 1400 } 1401 1402 /* 1403 * Check our as-of timestamp against the element. 1404 */ 1405 if (flags & HAMMER_CURSOR_ASOF) { 1406 if (hammer_btree_chkts(cursor->asof, 1407 &node->elms[i].base) != 0) { 1408 ++i; 1409 continue; 1410 } 1411 /* success */ 1412 } else { 1413 if (r > 0) { /* can only be +1 */ 1414 ++i; 1415 continue; 1416 } 1417 /* success */ 1418 } 1419 cursor->index = i; 1420 error = 0; 1421 if (hammer_debug_btree) { 1422 kprintf("RESULT-L %016llx[%d] (SUCCESS)\n", 1423 (long long)cursor->node->node_offset, i); 1424 } 1425 goto done; 1426 } 1427 1428 /* 1429 * The search of the leaf node failed. i is the insertion point. 1430 */ 1431 failed: 1432 if (hammer_debug_btree) { 1433 kprintf("RESULT-L %016llx[%d] (FAILED)\n", 1434 (long long)cursor->node->node_offset, i); 1435 } 1436 1437 /* 1438 * No exact match was found, i is now at the insertion point. 1439 * 1440 * If inserting split a full leaf before returning. This 1441 * may have the side effect of adjusting cursor->node and 1442 * cursor->index. 1443 */ 1444 cursor->index = i; 1445 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0 && 1446 btree_node_is_full(node)) { 1447 error = btree_split_leaf(cursor); 1448 if (error) { 1449 if (error != ENOSPC) 1450 goto done; 1451 enospc = 1; 1452 } 1453 /* 1454 * reload stale pointers 1455 */ 1456 /* NOT USED 1457 i = cursor->index; 1458 node = &cursor->node->internal; 1459 */ 1460 } 1461 1462 /* 1463 * We reached a leaf but did not find the key we were looking for. 1464 * If this is an insert we will be properly positioned for an insert 1465 * (ENOENT) or spike (ENOSPC) operation. 1466 */ 1467 error = enospc ? ENOSPC : ENOENT; 1468 done: 1469 return(error); 1470 } 1471 1472 /* 1473 * Heuristical search for the first element whos comparison is <= 1. May 1474 * return an index whos compare result is > 1 but may only return an index 1475 * whos compare result is <= 1 if it is the first element with that result. 1476 */ 1477 int 1478 hammer_btree_search_node(hammer_base_elm_t elm, hammer_node_ondisk_t node) 1479 { 1480 int b; 1481 int s; 1482 int i; 1483 int r; 1484 1485 /* 1486 * Don't bother if the node does not have very many elements 1487 */ 1488 b = 0; 1489 s = node->count; 1490 while (s - b > 4) { 1491 i = b + (s - b) / 2; 1492 ++hammer_stats_btree_elements; 1493 r = hammer_btree_cmp(elm, &node->elms[i].leaf.base); 1494 if (r <= 1) { 1495 s = i; 1496 } else { 1497 b = i; 1498 } 1499 } 1500 return(b); 1501 } 1502 1503 1504 /************************************************************************ 1505 * SPLITTING AND MERGING * 1506 ************************************************************************ 1507 * 1508 * These routines do all the dirty work required to split and merge nodes. 1509 */ 1510 1511 /* 1512 * Split an internal node into two nodes and move the separator at the split 1513 * point to the parent. 1514 * 1515 * (cursor->node, cursor->index) indicates the element the caller intends 1516 * to push into. We will adjust node and index if that element winds 1517 * up in the split node. 1518 * 1519 * If we are at the root of the filesystem a new root must be created with 1520 * two elements, one pointing to the original root and one pointing to the 1521 * newly allocated split node. 1522 */ 1523 static 1524 int 1525 btree_split_internal(hammer_cursor_t cursor) 1526 { 1527 hammer_node_ondisk_t ondisk; 1528 hammer_node_t node; 1529 hammer_node_t parent; 1530 hammer_node_t new_node; 1531 hammer_btree_elm_t elm; 1532 hammer_btree_elm_t parent_elm; 1533 struct hammer_node_lock lockroot; 1534 hammer_mount_t hmp = cursor->trans->hmp; 1535 hammer_off_t hint; 1536 int parent_index; 1537 int made_root; 1538 int split; 1539 int error; 1540 int i; 1541 const int esize = sizeof(*elm); 1542 1543 hammer_node_lock_init(&lockroot, cursor->node); 1544 error = hammer_btree_lock_children(cursor, 1, &lockroot, NULL); 1545 if (error) 1546 goto done; 1547 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1548 goto done; 1549 ++hammer_stats_btree_splits; 1550 1551 /* 1552 * Calculate the split point. If the insertion point is at the 1553 * end of the leaf we adjust the split point significantly to the 1554 * right to try to optimize node fill and flag it. If we hit 1555 * that same leaf again our heuristic failed and we don't try 1556 * to optimize node fill (it could lead to a degenerate case). 1557 */ 1558 node = cursor->node; 1559 ondisk = node->ondisk; 1560 KKASSERT(ondisk->count > 4); 1561 if (cursor->index == ondisk->count && 1562 (node->flags & HAMMER_NODE_NONLINEAR) == 0) { 1563 split = (ondisk->count + 1) * 3 / 4; 1564 node->flags |= HAMMER_NODE_NONLINEAR; 1565 } else { 1566 /* 1567 * We are splitting but elms[split] will be promoted to 1568 * the parent, leaving the right hand node with one less 1569 * element. If the insertion point will be on the 1570 * left-hand side adjust the split point to give the 1571 * right hand side one additional node. 1572 */ 1573 split = (ondisk->count + 1) / 2; 1574 if (cursor->index <= split) 1575 --split; 1576 } 1577 1578 /* 1579 * If we are at the root of the filesystem, create a new root node 1580 * with 1 element and split normally. Avoid making major 1581 * modifications until we know the whole operation will work. 1582 */ 1583 if (ondisk->parent == 0) { 1584 parent = hammer_alloc_btree(cursor->trans, 0, &error); 1585 if (parent == NULL) 1586 goto done; 1587 hammer_lock_ex(&parent->lock); 1588 hammer_modify_node_noundo(cursor->trans, parent); 1589 ondisk = parent->ondisk; 1590 ondisk->count = 1; 1591 ondisk->parent = 0; 1592 ondisk->mirror_tid = node->ondisk->mirror_tid; 1593 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1594 ondisk->elms[0].base = hmp->root_btree_beg; 1595 ondisk->elms[0].base.btype = node->ondisk->type; 1596 ondisk->elms[0].internal.subtree_offset = node->node_offset; 1597 ondisk->elms[1].base = hmp->root_btree_end; 1598 hammer_modify_node_done(parent); 1599 /* ondisk->elms[1].base.btype - not used */ 1600 made_root = 1; 1601 parent_index = 0; /* index of current node in parent */ 1602 } else { 1603 made_root = 0; 1604 parent = cursor->parent; 1605 parent_index = cursor->parent_index; 1606 } 1607 1608 /* 1609 * Calculate a hint for the allocation of the new B-Tree node. 1610 * The most likely expansion is coming from the insertion point 1611 * at cursor->index, so try to localize the allocation of our 1612 * new node to accomodate that sub-tree. 1613 * 1614 * Use the right-most sub-tree when expandinging on the right edge. 1615 * This is a very common case when copying a directory tree. 1616 */ 1617 if (cursor->index == ondisk->count) 1618 hint = ondisk->elms[cursor->index - 1].internal.subtree_offset; 1619 else 1620 hint = ondisk->elms[cursor->index].internal.subtree_offset; 1621 1622 /* 1623 * Split node into new_node at the split point. 1624 * 1625 * B O O O P N N B <-- P = node->elms[split] (index 4) 1626 * 0 1 2 3 4 5 6 <-- subtree indices 1627 * 1628 * x x P x x 1629 * s S S s 1630 * / \ 1631 * B O O O B B N N B <--- inner boundary points are 'P' 1632 * 0 1 2 3 4 5 6 1633 */ 1634 new_node = hammer_alloc_btree(cursor->trans, 0, &error); 1635 if (new_node == NULL) { 1636 if (made_root) { 1637 hammer_unlock(&parent->lock); 1638 hammer_delete_node(cursor->trans, parent); 1639 hammer_rel_node(parent); 1640 } 1641 goto done; 1642 } 1643 hammer_lock_ex(&new_node->lock); 1644 1645 /* 1646 * Create the new node. P becomes the left-hand boundary in the 1647 * new node. Copy the right-hand boundary as well. 1648 * 1649 * elm is the new separator. 1650 */ 1651 hammer_modify_node_noundo(cursor->trans, new_node); 1652 hammer_modify_node_all(cursor->trans, node); 1653 ondisk = node->ondisk; 1654 elm = &ondisk->elms[split]; 1655 bcopy(elm, &new_node->ondisk->elms[0], 1656 (ondisk->count - split + 1) * esize); 1657 new_node->ondisk->count = ondisk->count - split; 1658 new_node->ondisk->parent = parent->node_offset; 1659 new_node->ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1660 new_node->ondisk->mirror_tid = ondisk->mirror_tid; 1661 KKASSERT(ondisk->type == new_node->ondisk->type); 1662 hammer_cursor_split_node(node, new_node, split); 1663 1664 /* 1665 * Cleanup the original node. Elm (P) becomes the new boundary, 1666 * its subtree_offset was moved to the new node. If we had created 1667 * a new root its parent pointer may have changed. 1668 */ 1669 elm->internal.subtree_offset = 0; 1670 ondisk->count = split; 1671 1672 /* 1673 * Insert the separator into the parent, fixup the parent's 1674 * reference to the original node, and reference the new node. 1675 * The separator is P. 1676 * 1677 * Remember that base.count does not include the right-hand boundary. 1678 */ 1679 hammer_modify_node_all(cursor->trans, parent); 1680 ondisk = parent->ondisk; 1681 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS); 1682 parent_elm = &ondisk->elms[parent_index+1]; 1683 bcopy(parent_elm, parent_elm + 1, 1684 (ondisk->count - parent_index) * esize); 1685 parent_elm->internal.base = elm->base; /* separator P */ 1686 parent_elm->internal.base.btype = new_node->ondisk->type; 1687 parent_elm->internal.subtree_offset = new_node->node_offset; 1688 parent_elm->internal.mirror_tid = new_node->ondisk->mirror_tid; 1689 ++ondisk->count; 1690 hammer_modify_node_done(parent); 1691 hammer_cursor_inserted_element(parent, parent_index + 1); 1692 1693 /* 1694 * The children of new_node need their parent pointer set to new_node. 1695 * The children have already been locked by 1696 * hammer_btree_lock_children(). 1697 */ 1698 for (i = 0; i < new_node->ondisk->count; ++i) { 1699 elm = &new_node->ondisk->elms[i]; 1700 error = btree_set_parent(cursor->trans, new_node, elm); 1701 if (error) { 1702 panic("btree_split_internal: btree-fixup problem"); 1703 } 1704 } 1705 hammer_modify_node_done(new_node); 1706 1707 /* 1708 * The filesystem's root B-Tree pointer may have to be updated. 1709 */ 1710 if (made_root) { 1711 hammer_volume_t volume; 1712 1713 volume = hammer_get_root_volume(hmp, &error); 1714 KKASSERT(error == 0); 1715 1716 hammer_modify_volume_field(cursor->trans, volume, 1717 vol0_btree_root); 1718 volume->ondisk->vol0_btree_root = parent->node_offset; 1719 hammer_modify_volume_done(volume); 1720 node->ondisk->parent = parent->node_offset; 1721 if (cursor->parent) { 1722 hammer_unlock(&cursor->parent->lock); 1723 hammer_rel_node(cursor->parent); 1724 } 1725 cursor->parent = parent; /* lock'd and ref'd */ 1726 hammer_rel_volume(volume, 0); 1727 } 1728 hammer_modify_node_done(node); 1729 1730 /* 1731 * Ok, now adjust the cursor depending on which element the original 1732 * index was pointing at. If we are >= the split point the push node 1733 * is now in the new node. 1734 * 1735 * NOTE: If we are at the split point itself we cannot stay with the 1736 * original node because the push index will point at the right-hand 1737 * boundary, which is illegal. 1738 * 1739 * NOTE: The cursor's parent or parent_index must be adjusted for 1740 * the case where a new parent (new root) was created, and the case 1741 * where the cursor is now pointing at the split node. 1742 */ 1743 if (cursor->index >= split) { 1744 cursor->parent_index = parent_index + 1; 1745 cursor->index -= split; 1746 hammer_unlock(&cursor->node->lock); 1747 hammer_rel_node(cursor->node); 1748 cursor->node = new_node; /* locked and ref'd */ 1749 } else { 1750 cursor->parent_index = parent_index; 1751 hammer_unlock(&new_node->lock); 1752 hammer_rel_node(new_node); 1753 } 1754 1755 /* 1756 * Fixup left and right bounds 1757 */ 1758 parent_elm = &parent->ondisk->elms[cursor->parent_index]; 1759 cursor->left_bound = &parent_elm[0].internal.base; 1760 cursor->right_bound = &parent_elm[1].internal.base; 1761 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1762 &cursor->node->ondisk->elms[0].internal.base) <= 0); 1763 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1764 &cursor->node->ondisk->elms[cursor->node->ondisk->count].internal.base) >= 0); 1765 1766 done: 1767 hammer_btree_unlock_children(cursor->trans->hmp, &lockroot, NULL); 1768 hammer_cursor_downgrade(cursor); 1769 return (error); 1770 } 1771 1772 /* 1773 * Same as the above, but splits a full leaf node. 1774 * 1775 * This function 1776 */ 1777 static 1778 int 1779 btree_split_leaf(hammer_cursor_t cursor) 1780 { 1781 hammer_node_ondisk_t ondisk; 1782 hammer_node_t parent; 1783 hammer_node_t leaf; 1784 hammer_mount_t hmp; 1785 hammer_node_t new_leaf; 1786 hammer_btree_elm_t elm; 1787 hammer_btree_elm_t parent_elm; 1788 hammer_base_elm_t mid_boundary; 1789 hammer_off_t hint; 1790 int parent_index; 1791 int made_root; 1792 int split; 1793 int error; 1794 const size_t esize = sizeof(*elm); 1795 1796 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1797 return(error); 1798 ++hammer_stats_btree_splits; 1799 1800 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1801 &cursor->node->ondisk->elms[0].leaf.base) <= 0); 1802 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1803 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0); 1804 1805 /* 1806 * Calculate the split point. If the insertion point is at the 1807 * end of the leaf we adjust the split point significantly to the 1808 * right to try to optimize node fill and flag it. If we hit 1809 * that same leaf again our heuristic failed and we don't try 1810 * to optimize node fill (it could lead to a degenerate case). 1811 * 1812 * Spikes are made up of two leaf elements which cannot be 1813 * safely split. 1814 */ 1815 leaf = cursor->node; 1816 ondisk = leaf->ondisk; 1817 KKASSERT(ondisk->count > 4); 1818 if (cursor->index == ondisk->count && 1819 (leaf->flags & HAMMER_NODE_NONLINEAR) == 0) { 1820 split = (ondisk->count + 1) * 3 / 4; 1821 leaf->flags |= HAMMER_NODE_NONLINEAR; 1822 } else { 1823 split = (ondisk->count + 1) / 2; 1824 } 1825 1826 #if 0 1827 /* 1828 * If the insertion point is at the split point shift the 1829 * split point left so we don't have to worry about 1830 */ 1831 if (cursor->index == split) 1832 --split; 1833 #endif 1834 KKASSERT(split > 0 && split < ondisk->count); 1835 1836 error = 0; 1837 hmp = leaf->hmp; 1838 1839 elm = &ondisk->elms[split]; 1840 1841 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm[-1].leaf.base) <= 0); 1842 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->leaf.base) <= 0); 1843 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->leaf.base) > 0); 1844 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm[1].leaf.base) > 0); 1845 1846 /* 1847 * If we are at the root of the tree, create a new root node with 1848 * 1 element and split normally. Avoid making major modifications 1849 * until we know the whole operation will work. 1850 */ 1851 if (ondisk->parent == 0) { 1852 parent = hammer_alloc_btree(cursor->trans, 0, &error); 1853 if (parent == NULL) 1854 goto done; 1855 hammer_lock_ex(&parent->lock); 1856 hammer_modify_node_noundo(cursor->trans, parent); 1857 ondisk = parent->ondisk; 1858 ondisk->count = 1; 1859 ondisk->parent = 0; 1860 ondisk->mirror_tid = leaf->ondisk->mirror_tid; 1861 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1862 ondisk->elms[0].base = hmp->root_btree_beg; 1863 ondisk->elms[0].base.btype = leaf->ondisk->type; 1864 ondisk->elms[0].internal.subtree_offset = leaf->node_offset; 1865 ondisk->elms[1].base = hmp->root_btree_end; 1866 /* ondisk->elms[1].base.btype = not used */ 1867 hammer_modify_node_done(parent); 1868 made_root = 1; 1869 parent_index = 0; /* insertion point in parent */ 1870 } else { 1871 made_root = 0; 1872 parent = cursor->parent; 1873 parent_index = cursor->parent_index; 1874 } 1875 1876 /* 1877 * Calculate a hint for the allocation of the new B-Tree leaf node. 1878 * For now just try to localize it within the same bigblock as 1879 * the current leaf. 1880 * 1881 * If the insertion point is at the end of the leaf we recognize a 1882 * likely append sequence of some sort (data, meta-data, inodes, 1883 * whatever). Set the hint to zero to allocate out of linear space 1884 * instead of trying to completely fill previously hinted space. 1885 * 1886 * This also sets the stage for recursive splits to localize using 1887 * the new space. 1888 */ 1889 ondisk = leaf->ondisk; 1890 if (cursor->index == ondisk->count) 1891 hint = 0; 1892 else 1893 hint = leaf->node_offset; 1894 1895 /* 1896 * Split leaf into new_leaf at the split point. Select a separator 1897 * value in-between the two leafs but with a bent towards the right 1898 * leaf since comparisons use an 'elm >= separator' inequality. 1899 * 1900 * L L L L L L L L 1901 * 1902 * x x P x x 1903 * s S S s 1904 * / \ 1905 * L L L L L L L L 1906 */ 1907 new_leaf = hammer_alloc_btree(cursor->trans, 0, &error); 1908 if (new_leaf == NULL) { 1909 if (made_root) { 1910 hammer_unlock(&parent->lock); 1911 hammer_delete_node(cursor->trans, parent); 1912 hammer_rel_node(parent); 1913 } 1914 goto done; 1915 } 1916 hammer_lock_ex(&new_leaf->lock); 1917 1918 /* 1919 * Create the new node and copy the leaf elements from the split 1920 * point on to the new node. 1921 */ 1922 hammer_modify_node_all(cursor->trans, leaf); 1923 hammer_modify_node_noundo(cursor->trans, new_leaf); 1924 ondisk = leaf->ondisk; 1925 elm = &ondisk->elms[split]; 1926 bcopy(elm, &new_leaf->ondisk->elms[0], (ondisk->count - split) * esize); 1927 new_leaf->ondisk->count = ondisk->count - split; 1928 new_leaf->ondisk->parent = parent->node_offset; 1929 new_leaf->ondisk->type = HAMMER_BTREE_TYPE_LEAF; 1930 new_leaf->ondisk->mirror_tid = ondisk->mirror_tid; 1931 KKASSERT(ondisk->type == new_leaf->ondisk->type); 1932 hammer_modify_node_done(new_leaf); 1933 hammer_cursor_split_node(leaf, new_leaf, split); 1934 1935 /* 1936 * Cleanup the original node. Because this is a leaf node and 1937 * leaf nodes do not have a right-hand boundary, there 1938 * aren't any special edge cases to clean up. We just fixup the 1939 * count. 1940 */ 1941 ondisk->count = split; 1942 1943 /* 1944 * Insert the separator into the parent, fixup the parent's 1945 * reference to the original node, and reference the new node. 1946 * The separator is P. 1947 * 1948 * Remember that base.count does not include the right-hand boundary. 1949 * We are copying parent_index+1 to parent_index+2, not +0 to +1. 1950 */ 1951 hammer_modify_node_all(cursor->trans, parent); 1952 ondisk = parent->ondisk; 1953 KKASSERT(split != 0); 1954 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS); 1955 parent_elm = &ondisk->elms[parent_index+1]; 1956 bcopy(parent_elm, parent_elm + 1, 1957 (ondisk->count - parent_index) * esize); 1958 1959 hammer_make_separator(&elm[-1].base, &elm[0].base, &parent_elm->base); 1960 parent_elm->internal.base.btype = new_leaf->ondisk->type; 1961 parent_elm->internal.subtree_offset = new_leaf->node_offset; 1962 parent_elm->internal.mirror_tid = new_leaf->ondisk->mirror_tid; 1963 mid_boundary = &parent_elm->base; 1964 ++ondisk->count; 1965 hammer_modify_node_done(parent); 1966 hammer_cursor_inserted_element(parent, parent_index + 1); 1967 1968 /* 1969 * The filesystem's root B-Tree pointer may have to be updated. 1970 */ 1971 if (made_root) { 1972 hammer_volume_t volume; 1973 1974 volume = hammer_get_root_volume(hmp, &error); 1975 KKASSERT(error == 0); 1976 1977 hammer_modify_volume_field(cursor->trans, volume, 1978 vol0_btree_root); 1979 volume->ondisk->vol0_btree_root = parent->node_offset; 1980 hammer_modify_volume_done(volume); 1981 leaf->ondisk->parent = parent->node_offset; 1982 if (cursor->parent) { 1983 hammer_unlock(&cursor->parent->lock); 1984 hammer_rel_node(cursor->parent); 1985 } 1986 cursor->parent = parent; /* lock'd and ref'd */ 1987 hammer_rel_volume(volume, 0); 1988 } 1989 hammer_modify_node_done(leaf); 1990 1991 /* 1992 * Ok, now adjust the cursor depending on which element the original 1993 * index was pointing at. If we are >= the split point the push node 1994 * is now in the new node. 1995 * 1996 * NOTE: If we are at the split point itself we need to select the 1997 * old or new node based on where key_beg's insertion point will be. 1998 * If we pick the wrong side the inserted element will wind up in 1999 * the wrong leaf node and outside that node's bounds. 2000 */ 2001 if (cursor->index > split || 2002 (cursor->index == split && 2003 hammer_btree_cmp(&cursor->key_beg, mid_boundary) >= 0)) { 2004 cursor->parent_index = parent_index + 1; 2005 cursor->index -= split; 2006 hammer_unlock(&cursor->node->lock); 2007 hammer_rel_node(cursor->node); 2008 cursor->node = new_leaf; 2009 } else { 2010 cursor->parent_index = parent_index; 2011 hammer_unlock(&new_leaf->lock); 2012 hammer_rel_node(new_leaf); 2013 } 2014 2015 /* 2016 * Fixup left and right bounds 2017 */ 2018 parent_elm = &parent->ondisk->elms[cursor->parent_index]; 2019 cursor->left_bound = &parent_elm[0].internal.base; 2020 cursor->right_bound = &parent_elm[1].internal.base; 2021 2022 /* 2023 * Assert that the bounds are correct. 2024 */ 2025 KKASSERT(hammer_btree_cmp(cursor->left_bound, 2026 &cursor->node->ondisk->elms[0].leaf.base) <= 0); 2027 KKASSERT(hammer_btree_cmp(cursor->right_bound, 2028 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0); 2029 KKASSERT(hammer_btree_cmp(cursor->left_bound, &cursor->key_beg) <= 0); 2030 KKASSERT(hammer_btree_cmp(cursor->right_bound, &cursor->key_beg) > 0); 2031 2032 done: 2033 hammer_cursor_downgrade(cursor); 2034 return (error); 2035 } 2036 2037 #if 0 2038 2039 /* 2040 * Recursively correct the right-hand boundary's create_tid to (tid) as 2041 * long as the rest of the key matches. We have to recurse upward in 2042 * the tree as well as down the left side of each parent's right node. 2043 * 2044 * Return EDEADLK if we were only partially successful, forcing the caller 2045 * to try again. The original cursor is not modified. This routine can 2046 * also fail with EDEADLK if it is forced to throw away a portion of its 2047 * record history. 2048 * 2049 * The caller must pass a downgraded cursor to us (otherwise we can't dup it). 2050 */ 2051 struct hammer_rhb { 2052 TAILQ_ENTRY(hammer_rhb) entry; 2053 hammer_node_t node; 2054 int index; 2055 }; 2056 2057 TAILQ_HEAD(hammer_rhb_list, hammer_rhb); 2058 2059 int 2060 hammer_btree_correct_rhb(hammer_cursor_t cursor, hammer_tid_t tid) 2061 { 2062 struct hammer_mount *hmp; 2063 struct hammer_rhb_list rhb_list; 2064 hammer_base_elm_t elm; 2065 hammer_node_t orig_node; 2066 struct hammer_rhb *rhb; 2067 int orig_index; 2068 int error; 2069 2070 TAILQ_INIT(&rhb_list); 2071 hmp = cursor->trans->hmp; 2072 2073 /* 2074 * Save our position so we can restore it on return. This also 2075 * gives us a stable 'elm'. 2076 */ 2077 orig_node = cursor->node; 2078 hammer_ref_node(orig_node); 2079 hammer_lock_sh(&orig_node->lock); 2080 orig_index = cursor->index; 2081 elm = &orig_node->ondisk->elms[orig_index].base; 2082 2083 /* 2084 * Now build a list of parents going up, allocating a rhb 2085 * structure for each one. 2086 */ 2087 while (cursor->parent) { 2088 /* 2089 * Stop if we no longer have any right-bounds to fix up 2090 */ 2091 if (elm->obj_id != cursor->right_bound->obj_id || 2092 elm->rec_type != cursor->right_bound->rec_type || 2093 elm->key != cursor->right_bound->key) { 2094 break; 2095 } 2096 2097 /* 2098 * Stop if the right-hand bound's create_tid does not 2099 * need to be corrected. 2100 */ 2101 if (cursor->right_bound->create_tid >= tid) 2102 break; 2103 2104 rhb = kmalloc(sizeof(*rhb), hmp->m_misc, M_WAITOK|M_ZERO); 2105 rhb->node = cursor->parent; 2106 rhb->index = cursor->parent_index; 2107 hammer_ref_node(rhb->node); 2108 hammer_lock_sh(&rhb->node->lock); 2109 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry); 2110 2111 hammer_cursor_up(cursor); 2112 } 2113 2114 /* 2115 * now safely adjust the right hand bound for each rhb. This may 2116 * also require taking the right side of the tree and iterating down 2117 * ITS left side. 2118 */ 2119 error = 0; 2120 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2121 error = hammer_cursor_seek(cursor, rhb->node, rhb->index); 2122 if (error) 2123 break; 2124 TAILQ_REMOVE(&rhb_list, rhb, entry); 2125 hammer_unlock(&rhb->node->lock); 2126 hammer_rel_node(rhb->node); 2127 kfree(rhb, hmp->m_misc); 2128 2129 switch (cursor->node->ondisk->type) { 2130 case HAMMER_BTREE_TYPE_INTERNAL: 2131 /* 2132 * Right-boundary for parent at internal node 2133 * is one element to the right of the element whos 2134 * right boundary needs adjusting. We must then 2135 * traverse down the left side correcting any left 2136 * bounds (which may now be too far to the left). 2137 */ 2138 ++cursor->index; 2139 error = hammer_btree_correct_lhb(cursor, tid); 2140 break; 2141 default: 2142 panic("hammer_btree_correct_rhb(): Bad node type"); 2143 error = EINVAL; 2144 break; 2145 } 2146 } 2147 2148 /* 2149 * Cleanup 2150 */ 2151 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2152 TAILQ_REMOVE(&rhb_list, rhb, entry); 2153 hammer_unlock(&rhb->node->lock); 2154 hammer_rel_node(rhb->node); 2155 kfree(rhb, hmp->m_misc); 2156 } 2157 error = hammer_cursor_seek(cursor, orig_node, orig_index); 2158 hammer_unlock(&orig_node->lock); 2159 hammer_rel_node(orig_node); 2160 return (error); 2161 } 2162 2163 /* 2164 * Similar to rhb (in fact, rhb calls lhb), but corrects the left hand 2165 * bound going downward starting at the current cursor position. 2166 * 2167 * This function does not restore the cursor after use. 2168 */ 2169 int 2170 hammer_btree_correct_lhb(hammer_cursor_t cursor, hammer_tid_t tid) 2171 { 2172 struct hammer_rhb_list rhb_list; 2173 hammer_base_elm_t elm; 2174 hammer_base_elm_t cmp; 2175 struct hammer_rhb *rhb; 2176 struct hammer_mount *hmp; 2177 int error; 2178 2179 TAILQ_INIT(&rhb_list); 2180 hmp = cursor->trans->hmp; 2181 2182 cmp = &cursor->node->ondisk->elms[cursor->index].base; 2183 2184 /* 2185 * Record the node and traverse down the left-hand side for all 2186 * matching records needing a boundary correction. 2187 */ 2188 error = 0; 2189 for (;;) { 2190 rhb = kmalloc(sizeof(*rhb), hmp->m_misc, M_WAITOK|M_ZERO); 2191 rhb->node = cursor->node; 2192 rhb->index = cursor->index; 2193 hammer_ref_node(rhb->node); 2194 hammer_lock_sh(&rhb->node->lock); 2195 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry); 2196 2197 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2198 /* 2199 * Nothing to traverse down if we are at the right 2200 * boundary of an internal node. 2201 */ 2202 if (cursor->index == cursor->node->ondisk->count) 2203 break; 2204 } else { 2205 elm = &cursor->node->ondisk->elms[cursor->index].base; 2206 if (elm->btype == HAMMER_BTREE_TYPE_RECORD) 2207 break; 2208 panic("Illegal leaf record type %02x", elm->btype); 2209 } 2210 error = hammer_cursor_down(cursor); 2211 if (error) 2212 break; 2213 2214 elm = &cursor->node->ondisk->elms[cursor->index].base; 2215 if (elm->obj_id != cmp->obj_id || 2216 elm->rec_type != cmp->rec_type || 2217 elm->key != cmp->key) { 2218 break; 2219 } 2220 if (elm->create_tid >= tid) 2221 break; 2222 2223 } 2224 2225 /* 2226 * Now we can safely adjust the left-hand boundary from the bottom-up. 2227 * The last element we remove from the list is the caller's right hand 2228 * boundary, which must also be adjusted. 2229 */ 2230 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2231 error = hammer_cursor_seek(cursor, rhb->node, rhb->index); 2232 if (error) 2233 break; 2234 TAILQ_REMOVE(&rhb_list, rhb, entry); 2235 hammer_unlock(&rhb->node->lock); 2236 hammer_rel_node(rhb->node); 2237 kfree(rhb, hmp->m_misc); 2238 2239 elm = &cursor->node->ondisk->elms[cursor->index].base; 2240 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2241 hammer_modify_node(cursor->trans, cursor->node, 2242 &elm->create_tid, 2243 sizeof(elm->create_tid)); 2244 elm->create_tid = tid; 2245 hammer_modify_node_done(cursor->node); 2246 } else { 2247 panic("hammer_btree_correct_lhb(): Bad element type"); 2248 } 2249 } 2250 2251 /* 2252 * Cleanup 2253 */ 2254 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2255 TAILQ_REMOVE(&rhb_list, rhb, entry); 2256 hammer_unlock(&rhb->node->lock); 2257 hammer_rel_node(rhb->node); 2258 kfree(rhb, hmp->m_misc); 2259 } 2260 return (error); 2261 } 2262 2263 #endif 2264 2265 /* 2266 * Attempt to remove the locked, empty or want-to-be-empty B-Tree node at 2267 * (cursor->node). Returns 0 on success, EDEADLK if we could not complete 2268 * the operation due to a deadlock, or some other error. 2269 * 2270 * This routine is initially called with an empty leaf and may be 2271 * recursively called with single-element internal nodes. 2272 * 2273 * It should also be noted that when removing empty leaves we must be sure 2274 * to test and update mirror_tid because another thread may have deadlocked 2275 * against us (or someone) trying to propagate it up and cannot retry once 2276 * the node has been deleted. 2277 * 2278 * On return the cursor may end up pointing to an internal node, suitable 2279 * for further iteration but not for an immediate insertion or deletion. 2280 */ 2281 static int 2282 btree_remove(hammer_cursor_t cursor) 2283 { 2284 hammer_node_ondisk_t ondisk; 2285 hammer_btree_elm_t elm; 2286 hammer_node_t node; 2287 hammer_node_t parent; 2288 const int esize = sizeof(*elm); 2289 int error; 2290 2291 node = cursor->node; 2292 2293 /* 2294 * When deleting the root of the filesystem convert it to 2295 * an empty leaf node. Internal nodes cannot be empty. 2296 */ 2297 ondisk = node->ondisk; 2298 if (ondisk->parent == 0) { 2299 KKASSERT(cursor->parent == NULL); 2300 hammer_modify_node_all(cursor->trans, node); 2301 KKASSERT(ondisk == node->ondisk); 2302 ondisk->type = HAMMER_BTREE_TYPE_LEAF; 2303 ondisk->count = 0; 2304 hammer_modify_node_done(node); 2305 cursor->index = 0; 2306 return(0); 2307 } 2308 2309 parent = cursor->parent; 2310 2311 /* 2312 * Attempt to remove the parent's reference to the child. If the 2313 * parent would become empty we have to recurse. If we fail we 2314 * leave the parent pointing to an empty leaf node. 2315 * 2316 * We have to recurse successfully before we can delete the internal 2317 * node as it is illegal to have empty internal nodes. Even though 2318 * the operation may be aborted we must still fixup any unlocked 2319 * cursors as if we had deleted the element prior to recursing 2320 * (by calling hammer_cursor_deleted_element()) so those cursors 2321 * are properly forced up the chain by the recursion. 2322 */ 2323 if (parent->ondisk->count == 1) { 2324 /* 2325 * This special cursor_up_locked() call leaves the original 2326 * node exclusively locked and referenced, leaves the 2327 * original parent locked (as the new node), and locks the 2328 * new parent. It can return EDEADLK. 2329 * 2330 * We cannot call hammer_cursor_removed_node() until we are 2331 * actually able to remove the node. If we did then tracked 2332 * cursors in the middle of iterations could be repointed 2333 * to a parent node. If this occurs they could end up 2334 * scanning newly inserted records into the node (that could 2335 * not be deleted) when they push down again. 2336 * 2337 * Due to the way the recursion works the final parent is left 2338 * in cursor->parent after the recursion returns. Each 2339 * layer on the way back up is thus able to call 2340 * hammer_cursor_removed_node() and 'jump' the node up to 2341 * the (same) final parent. 2342 * 2343 * NOTE! The local variable 'parent' is invalid after we 2344 * call hammer_cursor_up_locked(). 2345 */ 2346 error = hammer_cursor_up_locked(cursor); 2347 parent = NULL; 2348 2349 if (error == 0) { 2350 hammer_cursor_deleted_element(cursor->node, 0); 2351 error = btree_remove(cursor); 2352 if (error == 0) { 2353 KKASSERT(node != cursor->node); 2354 hammer_cursor_removed_node( 2355 node, cursor->node, 2356 cursor->index); 2357 hammer_modify_node_all(cursor->trans, node); 2358 ondisk = node->ondisk; 2359 ondisk->type = HAMMER_BTREE_TYPE_DELETED; 2360 ondisk->count = 0; 2361 hammer_modify_node_done(node); 2362 hammer_flush_node(node, 0); 2363 hammer_delete_node(cursor->trans, node); 2364 } else { 2365 /* 2366 * Defer parent removal because we could not 2367 * get the lock, just let the leaf remain 2368 * empty. 2369 */ 2370 /**/ 2371 } 2372 hammer_unlock(&node->lock); 2373 hammer_rel_node(node); 2374 } else { 2375 /* 2376 * Defer parent removal because we could not 2377 * get the lock, just let the leaf remain 2378 * empty. 2379 */ 2380 /**/ 2381 } 2382 } else { 2383 KKASSERT(parent->ondisk->count > 1); 2384 2385 hammer_modify_node_all(cursor->trans, parent); 2386 ondisk = parent->ondisk; 2387 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_INTERNAL); 2388 2389 elm = &ondisk->elms[cursor->parent_index]; 2390 KKASSERT(elm->internal.subtree_offset == node->node_offset); 2391 KKASSERT(ondisk->count > 0); 2392 2393 /* 2394 * We must retain the highest mirror_tid. The deleted 2395 * range is now encompassed by the element to the left. 2396 * If we are already at the left edge the new left edge 2397 * inherits mirror_tid. 2398 * 2399 * Note that bounds of the parent to our parent may create 2400 * a gap to the left of our left-most node or to the right 2401 * of our right-most node. The gap is silently included 2402 * in the mirror_tid's area of effect from the point of view 2403 * of the scan. 2404 */ 2405 if (cursor->parent_index) { 2406 if (elm[-1].internal.mirror_tid < 2407 elm[0].internal.mirror_tid) { 2408 elm[-1].internal.mirror_tid = 2409 elm[0].internal.mirror_tid; 2410 } 2411 } else { 2412 if (elm[1].internal.mirror_tid < 2413 elm[0].internal.mirror_tid) { 2414 elm[1].internal.mirror_tid = 2415 elm[0].internal.mirror_tid; 2416 } 2417 } 2418 2419 /* 2420 * Delete the subtree reference in the parent. Include 2421 * boundary element at end. 2422 */ 2423 bcopy(&elm[1], &elm[0], 2424 (ondisk->count - cursor->parent_index) * esize); 2425 --ondisk->count; 2426 hammer_modify_node_done(parent); 2427 hammer_cursor_removed_node(node, parent, cursor->parent_index); 2428 hammer_cursor_deleted_element(parent, cursor->parent_index); 2429 hammer_flush_node(node, 0); 2430 hammer_delete_node(cursor->trans, node); 2431 2432 /* 2433 * cursor->node is invalid, cursor up to make the cursor 2434 * valid again. We have to flag the condition in case 2435 * another thread wiggles an insertion in during an 2436 * iteration. 2437 */ 2438 cursor->flags |= HAMMER_CURSOR_ITERATE_CHECK; 2439 error = hammer_cursor_up(cursor); 2440 } 2441 return (error); 2442 } 2443 2444 /* 2445 * Propagate cursor->trans->tid up the B-Tree starting at the current 2446 * cursor position using pseudofs info gleaned from the passed inode. 2447 * 2448 * The passed inode has no relationship to the cursor position other 2449 * then being in the same pseudofs as the insertion or deletion we 2450 * are propagating the mirror_tid for. 2451 * 2452 * WARNING! Because we push and pop the passed cursor, it may be 2453 * modified by other B-Tree operations while it is unlocked 2454 * and things like the node & leaf pointers, and indexes might 2455 * change. 2456 */ 2457 void 2458 hammer_btree_do_propagation(hammer_cursor_t cursor, 2459 hammer_pseudofs_inmem_t pfsm, 2460 hammer_btree_leaf_elm_t leaf) 2461 { 2462 hammer_cursor_t ncursor; 2463 hammer_tid_t mirror_tid; 2464 int error; 2465 2466 /* 2467 * We do not propagate a mirror_tid if the filesystem was mounted 2468 * in no-mirror mode. 2469 */ 2470 if (cursor->trans->hmp->master_id < 0) 2471 return; 2472 2473 /* 2474 * This is a bit of a hack because we cannot deadlock or return 2475 * EDEADLK here. The related operation has already completed and 2476 * we must propagate the mirror_tid now regardless. 2477 * 2478 * Generate a new cursor which inherits the original's locks and 2479 * unlock the original. Use the new cursor to propagate the 2480 * mirror_tid. Then clean up the new cursor and reacquire locks 2481 * on the original. 2482 * 2483 * hammer_dup_cursor() cannot dup locks. The dup inherits the 2484 * original's locks and the original is tracked and must be 2485 * re-locked. 2486 */ 2487 mirror_tid = cursor->node->ondisk->mirror_tid; 2488 KKASSERT(mirror_tid != 0); 2489 ncursor = hammer_push_cursor(cursor); 2490 error = hammer_btree_mirror_propagate(ncursor, mirror_tid); 2491 KKASSERT(error == 0); 2492 hammer_pop_cursor(cursor, ncursor); 2493 /* WARNING: cursor's leaf pointer may change after pop */ 2494 } 2495 2496 2497 /* 2498 * Propagate a mirror TID update upwards through the B-Tree to the root. 2499 * 2500 * A locked internal node must be passed in. The node will remain locked 2501 * on return. 2502 * 2503 * This function syncs mirror_tid at the specified internal node's element, 2504 * adjusts the node's aggregation mirror_tid, and then recurses upwards. 2505 */ 2506 static int 2507 hammer_btree_mirror_propagate(hammer_cursor_t cursor, hammer_tid_t mirror_tid) 2508 { 2509 hammer_btree_internal_elm_t elm; 2510 hammer_node_t node; 2511 int error; 2512 2513 for (;;) { 2514 error = hammer_cursor_up(cursor); 2515 if (error == 0) 2516 error = hammer_cursor_upgrade(cursor); 2517 2518 /* 2519 * We can ignore HAMMER_CURSOR_ITERATE_CHECK, the 2520 * cursor will still be properly positioned for 2521 * mirror propagation, just not for iterations. 2522 */ 2523 while (error == EDEADLK) { 2524 hammer_recover_cursor(cursor); 2525 error = hammer_cursor_upgrade(cursor); 2526 } 2527 if (error) 2528 break; 2529 2530 /* 2531 * If the cursor deadlocked it could end up at a leaf 2532 * after we lost the lock. 2533 */ 2534 node = cursor->node; 2535 if (node->ondisk->type != HAMMER_BTREE_TYPE_INTERNAL) 2536 continue; 2537 2538 /* 2539 * Adjust the node's element 2540 */ 2541 elm = &node->ondisk->elms[cursor->index].internal; 2542 if (elm->mirror_tid >= mirror_tid) 2543 break; 2544 hammer_modify_node(cursor->trans, node, &elm->mirror_tid, 2545 sizeof(elm->mirror_tid)); 2546 elm->mirror_tid = mirror_tid; 2547 hammer_modify_node_done(node); 2548 if (hammer_debug_general & 0x0002) { 2549 kprintf("mirror_propagate: propagate " 2550 "%016llx @%016llx:%d\n", 2551 (long long)mirror_tid, 2552 (long long)node->node_offset, 2553 cursor->index); 2554 } 2555 2556 2557 /* 2558 * Adjust the node's mirror_tid aggregator 2559 */ 2560 if (node->ondisk->mirror_tid >= mirror_tid) 2561 return(0); 2562 hammer_modify_node_field(cursor->trans, node, mirror_tid); 2563 node->ondisk->mirror_tid = mirror_tid; 2564 hammer_modify_node_done(node); 2565 if (hammer_debug_general & 0x0002) { 2566 kprintf("mirror_propagate: propagate " 2567 "%016llx @%016llx\n", 2568 (long long)mirror_tid, 2569 (long long)node->node_offset); 2570 } 2571 } 2572 if (error == ENOENT) 2573 error = 0; 2574 return(error); 2575 } 2576 2577 hammer_node_t 2578 hammer_btree_get_parent(hammer_transaction_t trans, hammer_node_t node, 2579 int *parent_indexp, int *errorp, int try_exclusive) 2580 { 2581 hammer_node_t parent; 2582 hammer_btree_elm_t elm; 2583 int i; 2584 2585 /* 2586 * Get the node 2587 */ 2588 parent = hammer_get_node(trans, node->ondisk->parent, 0, errorp); 2589 if (*errorp) { 2590 KKASSERT(parent == NULL); 2591 return(NULL); 2592 } 2593 KKASSERT ((parent->flags & HAMMER_NODE_DELETED) == 0); 2594 2595 /* 2596 * Lock the node 2597 */ 2598 if (try_exclusive) { 2599 if (hammer_lock_ex_try(&parent->lock)) { 2600 hammer_rel_node(parent); 2601 *errorp = EDEADLK; 2602 return(NULL); 2603 } 2604 } else { 2605 hammer_lock_sh(&parent->lock); 2606 } 2607 2608 /* 2609 * Figure out which element in the parent is pointing to the 2610 * child. 2611 */ 2612 if (node->ondisk->count) { 2613 i = hammer_btree_search_node(&node->ondisk->elms[0].base, 2614 parent->ondisk); 2615 } else { 2616 i = 0; 2617 } 2618 while (i < parent->ondisk->count) { 2619 elm = &parent->ondisk->elms[i]; 2620 if (elm->internal.subtree_offset == node->node_offset) 2621 break; 2622 ++i; 2623 } 2624 if (i == parent->ondisk->count) { 2625 hammer_unlock(&parent->lock); 2626 panic("Bad B-Tree link: parent %p node %p\n", parent, node); 2627 } 2628 *parent_indexp = i; 2629 KKASSERT(*errorp == 0); 2630 return(parent); 2631 } 2632 2633 /* 2634 * The element (elm) has been moved to a new internal node (node). 2635 * 2636 * If the element represents a pointer to an internal node that node's 2637 * parent must be adjusted to the element's new location. 2638 * 2639 * XXX deadlock potential here with our exclusive locks 2640 */ 2641 int 2642 btree_set_parent(hammer_transaction_t trans, hammer_node_t node, 2643 hammer_btree_elm_t elm) 2644 { 2645 hammer_node_t child; 2646 int error; 2647 2648 error = 0; 2649 2650 switch(elm->base.btype) { 2651 case HAMMER_BTREE_TYPE_INTERNAL: 2652 case HAMMER_BTREE_TYPE_LEAF: 2653 child = hammer_get_node(trans, elm->internal.subtree_offset, 2654 0, &error); 2655 if (error == 0) { 2656 hammer_modify_node_field(trans, child, parent); 2657 child->ondisk->parent = node->node_offset; 2658 hammer_modify_node_done(child); 2659 hammer_rel_node(child); 2660 } 2661 break; 2662 default: 2663 break; 2664 } 2665 return(error); 2666 } 2667 2668 /* 2669 * Initialize the root of a recursive B-Tree node lock list structure. 2670 */ 2671 void 2672 hammer_node_lock_init(hammer_node_lock_t parent, hammer_node_t node) 2673 { 2674 TAILQ_INIT(&parent->list); 2675 parent->parent = NULL; 2676 parent->node = node; 2677 parent->index = -1; 2678 parent->count = node->ondisk->count; 2679 parent->copy = NULL; 2680 parent->flags = 0; 2681 } 2682 2683 /* 2684 * Initialize a cache of hammer_node_lock's including space allocated 2685 * for node copies. 2686 * 2687 * This is used by the rebalancing code to preallocate the copy space 2688 * for ~4096 B-Tree nodes (16MB of data) prior to acquiring any HAMMER 2689 * locks, otherwise we can blow out the pageout daemon's emergency 2690 * reserve and deadlock it. 2691 * 2692 * NOTE: HAMMER_NODE_LOCK_LCACHE is not set on items cached in the lcache. 2693 * The flag is set when the item is pulled off the cache for use. 2694 */ 2695 void 2696 hammer_btree_lcache_init(hammer_mount_t hmp, hammer_node_lock_t lcache, 2697 int depth) 2698 { 2699 hammer_node_lock_t item; 2700 int count; 2701 2702 for (count = 1; depth; --depth) 2703 count *= HAMMER_BTREE_LEAF_ELMS; 2704 bzero(lcache, sizeof(*lcache)); 2705 TAILQ_INIT(&lcache->list); 2706 while (count) { 2707 item = kmalloc(sizeof(*item), hmp->m_misc, M_WAITOK|M_ZERO); 2708 item->copy = kmalloc(sizeof(*item->copy), 2709 hmp->m_misc, M_WAITOK); 2710 TAILQ_INIT(&item->list); 2711 TAILQ_INSERT_TAIL(&lcache->list, item, entry); 2712 --count; 2713 } 2714 } 2715 2716 void 2717 hammer_btree_lcache_free(hammer_mount_t hmp, hammer_node_lock_t lcache) 2718 { 2719 hammer_node_lock_t item; 2720 2721 while ((item = TAILQ_FIRST(&lcache->list)) != NULL) { 2722 TAILQ_REMOVE(&lcache->list, item, entry); 2723 KKASSERT(item->copy); 2724 KKASSERT(TAILQ_EMPTY(&item->list)); 2725 kfree(item->copy, hmp->m_misc); 2726 kfree(item, hmp->m_misc); 2727 } 2728 KKASSERT(lcache->copy == NULL); 2729 } 2730 2731 /* 2732 * Exclusively lock all the children of node. This is used by the split 2733 * code to prevent anyone from accessing the children of a cursor node 2734 * while we fix-up its parent offset. 2735 * 2736 * If we don't lock the children we can really mess up cursors which block 2737 * trying to cursor-up into our node. 2738 * 2739 * On failure EDEADLK (or some other error) is returned. If a deadlock 2740 * error is returned the cursor is adjusted to block on termination. 2741 * 2742 * The caller is responsible for managing parent->node, the root's node 2743 * is usually aliased from a cursor. 2744 */ 2745 int 2746 hammer_btree_lock_children(hammer_cursor_t cursor, int depth, 2747 hammer_node_lock_t parent, 2748 hammer_node_lock_t lcache) 2749 { 2750 hammer_node_t node; 2751 hammer_node_lock_t item; 2752 hammer_node_ondisk_t ondisk; 2753 hammer_btree_elm_t elm; 2754 hammer_node_t child; 2755 struct hammer_mount *hmp; 2756 int error; 2757 int i; 2758 2759 node = parent->node; 2760 ondisk = node->ondisk; 2761 error = 0; 2762 hmp = cursor->trans->hmp; 2763 2764 /* 2765 * We really do not want to block on I/O with exclusive locks held, 2766 * pre-get the children before trying to lock the mess. This is 2767 * only done one-level deep for now. 2768 */ 2769 for (i = 0; i < ondisk->count; ++i) { 2770 ++hammer_stats_btree_elements; 2771 elm = &ondisk->elms[i]; 2772 if (elm->base.btype != HAMMER_BTREE_TYPE_LEAF && 2773 elm->base.btype != HAMMER_BTREE_TYPE_INTERNAL) { 2774 continue; 2775 } 2776 child = hammer_get_node(cursor->trans, 2777 elm->internal.subtree_offset, 2778 0, &error); 2779 if (child) 2780 hammer_rel_node(child); 2781 } 2782 2783 /* 2784 * Do it for real 2785 */ 2786 for (i = 0; error == 0 && i < ondisk->count; ++i) { 2787 ++hammer_stats_btree_elements; 2788 elm = &ondisk->elms[i]; 2789 2790 switch(elm->base.btype) { 2791 case HAMMER_BTREE_TYPE_INTERNAL: 2792 case HAMMER_BTREE_TYPE_LEAF: 2793 KKASSERT(elm->internal.subtree_offset != 0); 2794 child = hammer_get_node(cursor->trans, 2795 elm->internal.subtree_offset, 2796 0, &error); 2797 break; 2798 default: 2799 child = NULL; 2800 break; 2801 } 2802 if (child) { 2803 if (hammer_lock_ex_try(&child->lock) != 0) { 2804 if (cursor->deadlk_node == NULL) { 2805 cursor->deadlk_node = child; 2806 hammer_ref_node(cursor->deadlk_node); 2807 } 2808 error = EDEADLK; 2809 hammer_rel_node(child); 2810 } else { 2811 if (lcache) { 2812 item = TAILQ_FIRST(&lcache->list); 2813 KKASSERT(item != NULL); 2814 item->flags |= HAMMER_NODE_LOCK_LCACHE; 2815 TAILQ_REMOVE(&lcache->list, 2816 item, entry); 2817 } else { 2818 item = kmalloc(sizeof(*item), 2819 hmp->m_misc, 2820 M_WAITOK|M_ZERO); 2821 TAILQ_INIT(&item->list); 2822 } 2823 2824 TAILQ_INSERT_TAIL(&parent->list, item, entry); 2825 item->parent = parent; 2826 item->node = child; 2827 item->index = i; 2828 item->count = child->ondisk->count; 2829 2830 /* 2831 * Recurse (used by the rebalancing code) 2832 */ 2833 if (depth > 1 && elm->base.btype == HAMMER_BTREE_TYPE_INTERNAL) { 2834 error = hammer_btree_lock_children( 2835 cursor, 2836 depth - 1, 2837 item, 2838 lcache); 2839 } 2840 } 2841 } 2842 } 2843 if (error) 2844 hammer_btree_unlock_children(hmp, parent, lcache); 2845 return(error); 2846 } 2847 2848 /* 2849 * Create an in-memory copy of all B-Tree nodes listed, recursively, 2850 * including the parent. 2851 */ 2852 void 2853 hammer_btree_lock_copy(hammer_cursor_t cursor, hammer_node_lock_t parent) 2854 { 2855 hammer_mount_t hmp = cursor->trans->hmp; 2856 hammer_node_lock_t item; 2857 2858 if (parent->copy == NULL) { 2859 KKASSERT((parent->flags & HAMMER_NODE_LOCK_LCACHE) == 0); 2860 parent->copy = kmalloc(sizeof(*parent->copy), 2861 hmp->m_misc, M_WAITOK); 2862 } 2863 KKASSERT((parent->flags & HAMMER_NODE_LOCK_UPDATED) == 0); 2864 *parent->copy = *parent->node->ondisk; 2865 TAILQ_FOREACH(item, &parent->list, entry) { 2866 hammer_btree_lock_copy(cursor, item); 2867 } 2868 } 2869 2870 /* 2871 * Recursively sync modified copies to the media. 2872 */ 2873 int 2874 hammer_btree_sync_copy(hammer_cursor_t cursor, hammer_node_lock_t parent) 2875 { 2876 hammer_node_lock_t item; 2877 int count = 0; 2878 2879 if (parent->flags & HAMMER_NODE_LOCK_UPDATED) { 2880 ++count; 2881 hammer_modify_node_all(cursor->trans, parent->node); 2882 *parent->node->ondisk = *parent->copy; 2883 hammer_modify_node_done(parent->node); 2884 if (parent->copy->type == HAMMER_BTREE_TYPE_DELETED) { 2885 hammer_flush_node(parent->node, 0); 2886 hammer_delete_node(cursor->trans, parent->node); 2887 } 2888 } 2889 TAILQ_FOREACH(item, &parent->list, entry) { 2890 count += hammer_btree_sync_copy(cursor, item); 2891 } 2892 return(count); 2893 } 2894 2895 /* 2896 * Release previously obtained node locks. The caller is responsible for 2897 * cleaning up parent->node itself (its usually just aliased from a cursor), 2898 * but this function will take care of the copies. 2899 * 2900 * NOTE: The root node is not placed in the lcache and node->copy is not 2901 * deallocated when lcache != NULL. 2902 */ 2903 void 2904 hammer_btree_unlock_children(hammer_mount_t hmp, hammer_node_lock_t parent, 2905 hammer_node_lock_t lcache) 2906 { 2907 hammer_node_lock_t item; 2908 hammer_node_ondisk_t copy; 2909 2910 while ((item = TAILQ_FIRST(&parent->list)) != NULL) { 2911 TAILQ_REMOVE(&parent->list, item, entry); 2912 hammer_btree_unlock_children(hmp, item, lcache); 2913 hammer_unlock(&item->node->lock); 2914 hammer_rel_node(item->node); 2915 if (lcache) { 2916 /* 2917 * NOTE: When placing the item back in the lcache 2918 * the flag is cleared by the bzero(). 2919 * Remaining fields are cleared as a safety 2920 * measure. 2921 */ 2922 KKASSERT(item->flags & HAMMER_NODE_LOCK_LCACHE); 2923 KKASSERT(TAILQ_EMPTY(&item->list)); 2924 copy = item->copy; 2925 bzero(item, sizeof(*item)); 2926 TAILQ_INIT(&item->list); 2927 item->copy = copy; 2928 if (copy) 2929 bzero(copy, sizeof(*copy)); 2930 TAILQ_INSERT_TAIL(&lcache->list, item, entry); 2931 } else { 2932 kfree(item, hmp->m_misc); 2933 } 2934 } 2935 if (parent->copy && (parent->flags & HAMMER_NODE_LOCK_LCACHE) == 0) { 2936 kfree(parent->copy, hmp->m_misc); 2937 parent->copy = NULL; /* safety */ 2938 } 2939 } 2940 2941 /************************************************************************ 2942 * MISCELLANIOUS SUPPORT * 2943 ************************************************************************/ 2944 2945 /* 2946 * Compare two B-Tree elements, return -N, 0, or +N (e.g. similar to strcmp). 2947 * 2948 * Note that for this particular function a return value of -1, 0, or +1 2949 * can denote a match if create_tid is otherwise discounted. A create_tid 2950 * of zero is considered to be 'infinity' in comparisons. 2951 * 2952 * See also hammer_rec_rb_compare() and hammer_rec_cmp() in hammer_object.c. 2953 */ 2954 int 2955 hammer_btree_cmp(hammer_base_elm_t key1, hammer_base_elm_t key2) 2956 { 2957 if (key1->localization < key2->localization) 2958 return(-5); 2959 if (key1->localization > key2->localization) 2960 return(5); 2961 2962 if (key1->obj_id < key2->obj_id) 2963 return(-4); 2964 if (key1->obj_id > key2->obj_id) 2965 return(4); 2966 2967 if (key1->rec_type < key2->rec_type) 2968 return(-3); 2969 if (key1->rec_type > key2->rec_type) 2970 return(3); 2971 2972 if (key1->key < key2->key) 2973 return(-2); 2974 if (key1->key > key2->key) 2975 return(2); 2976 2977 /* 2978 * A create_tid of zero indicates a record which is undeletable 2979 * and must be considered to have a value of positive infinity. 2980 */ 2981 if (key1->create_tid == 0) { 2982 if (key2->create_tid == 0) 2983 return(0); 2984 return(1); 2985 } 2986 if (key2->create_tid == 0) 2987 return(-1); 2988 if (key1->create_tid < key2->create_tid) 2989 return(-1); 2990 if (key1->create_tid > key2->create_tid) 2991 return(1); 2992 return(0); 2993 } 2994 2995 /* 2996 * Test a timestamp against an element to determine whether the 2997 * element is visible. A timestamp of 0 means 'infinity'. 2998 */ 2999 int 3000 hammer_btree_chkts(hammer_tid_t asof, hammer_base_elm_t base) 3001 { 3002 if (asof == 0) { 3003 if (base->delete_tid) 3004 return(1); 3005 return(0); 3006 } 3007 if (asof < base->create_tid) 3008 return(-1); 3009 if (base->delete_tid && asof >= base->delete_tid) 3010 return(1); 3011 return(0); 3012 } 3013 3014 /* 3015 * Create a separator half way inbetween key1 and key2. For fields just 3016 * one unit apart, the separator will match key2. key1 is on the left-hand 3017 * side and key2 is on the right-hand side. 3018 * 3019 * key2 must be >= the separator. It is ok for the separator to match key2. 3020 * 3021 * NOTE: Even if key1 does not match key2, the separator may wind up matching 3022 * key2. 3023 * 3024 * NOTE: It might be beneficial to just scrap this whole mess and just 3025 * set the separator to key2. 3026 */ 3027 #define MAKE_SEPARATOR(key1, key2, dest, field) \ 3028 dest->field = key1->field + ((key2->field - key1->field + 1) >> 1); 3029 3030 static void 3031 hammer_make_separator(hammer_base_elm_t key1, hammer_base_elm_t key2, 3032 hammer_base_elm_t dest) 3033 { 3034 bzero(dest, sizeof(*dest)); 3035 3036 dest->rec_type = key2->rec_type; 3037 dest->key = key2->key; 3038 dest->obj_id = key2->obj_id; 3039 dest->create_tid = key2->create_tid; 3040 3041 MAKE_SEPARATOR(key1, key2, dest, localization); 3042 if (key1->localization == key2->localization) { 3043 MAKE_SEPARATOR(key1, key2, dest, obj_id); 3044 if (key1->obj_id == key2->obj_id) { 3045 MAKE_SEPARATOR(key1, key2, dest, rec_type); 3046 if (key1->rec_type == key2->rec_type) { 3047 MAKE_SEPARATOR(key1, key2, dest, key); 3048 /* 3049 * Don't bother creating a separator for 3050 * create_tid, which also conveniently avoids 3051 * having to handle the create_tid == 0 3052 * (infinity) case. Just leave create_tid 3053 * set to key2. 3054 * 3055 * Worst case, dest matches key2 exactly, 3056 * which is acceptable. 3057 */ 3058 } 3059 } 3060 } 3061 } 3062 3063 #undef MAKE_SEPARATOR 3064 3065 /* 3066 * Return whether a generic internal or leaf node is full 3067 */ 3068 static int 3069 btree_node_is_full(hammer_node_ondisk_t node) 3070 { 3071 switch(node->type) { 3072 case HAMMER_BTREE_TYPE_INTERNAL: 3073 if (node->count == HAMMER_BTREE_INT_ELMS) 3074 return(1); 3075 break; 3076 case HAMMER_BTREE_TYPE_LEAF: 3077 if (node->count == HAMMER_BTREE_LEAF_ELMS) 3078 return(1); 3079 break; 3080 default: 3081 panic("illegal btree subtype"); 3082 } 3083 return(0); 3084 } 3085 3086 #if 0 3087 static int 3088 btree_max_elements(u_int8_t type) 3089 { 3090 if (type == HAMMER_BTREE_TYPE_LEAF) 3091 return(HAMMER_BTREE_LEAF_ELMS); 3092 if (type == HAMMER_BTREE_TYPE_INTERNAL) 3093 return(HAMMER_BTREE_INT_ELMS); 3094 panic("btree_max_elements: bad type %d\n", type); 3095 } 3096 #endif 3097 3098 void 3099 hammer_print_btree_node(hammer_node_ondisk_t ondisk) 3100 { 3101 hammer_btree_elm_t elm; 3102 int i; 3103 3104 kprintf("node %p count=%d parent=%016llx type=%c\n", 3105 ondisk, ondisk->count, 3106 (long long)ondisk->parent, ondisk->type); 3107 3108 /* 3109 * Dump both boundary elements if an internal node 3110 */ 3111 if (ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 3112 for (i = 0; i <= ondisk->count; ++i) { 3113 elm = &ondisk->elms[i]; 3114 hammer_print_btree_elm(elm, ondisk->type, i); 3115 } 3116 } else { 3117 for (i = 0; i < ondisk->count; ++i) { 3118 elm = &ondisk->elms[i]; 3119 hammer_print_btree_elm(elm, ondisk->type, i); 3120 } 3121 } 3122 } 3123 3124 void 3125 hammer_print_btree_elm(hammer_btree_elm_t elm, u_int8_t type, int i) 3126 { 3127 kprintf(" %2d", i); 3128 kprintf("\tobj_id = %016llx\n", (long long)elm->base.obj_id); 3129 kprintf("\tkey = %016llx\n", (long long)elm->base.key); 3130 kprintf("\tcreate_tid = %016llx\n", (long long)elm->base.create_tid); 3131 kprintf("\tdelete_tid = %016llx\n", (long long)elm->base.delete_tid); 3132 kprintf("\trec_type = %04x\n", elm->base.rec_type); 3133 kprintf("\tobj_type = %02x\n", elm->base.obj_type); 3134 kprintf("\tbtype = %02x (%c)\n", 3135 elm->base.btype, 3136 (elm->base.btype ? elm->base.btype : '?')); 3137 kprintf("\tlocalization = %02x\n", elm->base.localization); 3138 3139 switch(type) { 3140 case HAMMER_BTREE_TYPE_INTERNAL: 3141 kprintf("\tsubtree_off = %016llx\n", 3142 (long long)elm->internal.subtree_offset); 3143 break; 3144 case HAMMER_BTREE_TYPE_RECORD: 3145 kprintf("\tdata_offset = %016llx\n", 3146 (long long)elm->leaf.data_offset); 3147 kprintf("\tdata_len = %08x\n", elm->leaf.data_len); 3148 kprintf("\tdata_crc = %08x\n", elm->leaf.data_crc); 3149 break; 3150 } 3151 } 3152