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 * NOTE! EDEADLK *CANNOT* be returned by this procedure. 114 */ 115 int 116 hammer_btree_iterate(hammer_cursor_t cursor) 117 { 118 hammer_node_ondisk_t node; 119 hammer_btree_elm_t elm; 120 int error = 0; 121 int r; 122 int s; 123 124 /* 125 * Skip past the current record 126 */ 127 node = cursor->node->ondisk; 128 if (node == NULL) 129 return(ENOENT); 130 if (cursor->index < node->count && 131 (cursor->flags & HAMMER_CURSOR_ATEDISK)) { 132 ++cursor->index; 133 } 134 135 /* 136 * Loop until an element is found or we are done. 137 */ 138 for (;;) { 139 /* 140 * We iterate up the tree and then index over one element 141 * while we are at the last element in the current node. 142 * 143 * If we are at the root of the filesystem, cursor_up 144 * returns ENOENT. 145 * 146 * XXX this could be optimized by storing the information in 147 * the parent reference. 148 * 149 * XXX we can lose the node lock temporarily, this could mess 150 * up our scan. 151 */ 152 ++hammer_stats_btree_iterations; 153 hammer_flusher_clean_loose_ios(cursor->trans->hmp); 154 155 if (cursor->index == node->count) { 156 if (hammer_debug_btree) { 157 kprintf("BRACKETU %016llx[%d] -> %016llx[%d] (td=%p)\n", 158 cursor->node->node_offset, 159 cursor->index, 160 (cursor->parent ? cursor->parent->node_offset : -1), 161 cursor->parent_index, 162 curthread); 163 } 164 KKASSERT(cursor->parent == NULL || cursor->parent->ondisk->elms[cursor->parent_index].internal.subtree_offset == cursor->node->node_offset); 165 error = hammer_cursor_up(cursor); 166 if (error) 167 break; 168 /* reload stale pointer */ 169 node = cursor->node->ondisk; 170 KKASSERT(cursor->index != node->count); 171 172 /* 173 * If we are reblocking we want to return internal 174 * nodes. Note that the internal node will be 175 * returned multiple times, on each upward recursion 176 * from its children. The caller selects which 177 * revisit it cares about (usually first or last only). 178 */ 179 if (cursor->flags & HAMMER_CURSOR_REBLOCKING) { 180 cursor->flags |= HAMMER_CURSOR_ATEDISK; 181 return(0); 182 } 183 ++cursor->index; 184 continue; 185 } 186 187 /* 188 * Check internal or leaf element. Determine if the record 189 * at the cursor has gone beyond the end of our range. 190 * 191 * We recurse down through internal nodes. 192 */ 193 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) { 194 elm = &node->elms[cursor->index]; 195 196 r = hammer_btree_cmp(&cursor->key_end, &elm[0].base); 197 s = hammer_btree_cmp(&cursor->key_beg, &elm[1].base); 198 if (hammer_debug_btree) { 199 kprintf("BRACKETL %016llx[%d] %016llx %02x %016llx lo=%02x %d (td=%p)\n", 200 cursor->node->node_offset, 201 cursor->index, 202 elm[0].internal.base.obj_id, 203 elm[0].internal.base.rec_type, 204 elm[0].internal.base.key, 205 elm[0].internal.base.localization, 206 r, 207 curthread 208 ); 209 kprintf("BRACKETR %016llx[%d] %016llx %02x %016llx lo=%02x %d\n", 210 cursor->node->node_offset, 211 cursor->index + 1, 212 elm[1].internal.base.obj_id, 213 elm[1].internal.base.rec_type, 214 elm[1].internal.base.key, 215 elm[1].internal.base.localization, 216 s 217 ); 218 } 219 220 if (r < 0) { 221 error = ENOENT; 222 break; 223 } 224 if (r == 0 && (cursor->flags & 225 HAMMER_CURSOR_END_INCLUSIVE) == 0) { 226 error = ENOENT; 227 break; 228 } 229 KKASSERT(s <= 0); 230 231 /* 232 * Better not be zero 233 */ 234 KKASSERT(elm->internal.subtree_offset != 0); 235 236 /* 237 * If running the mirror filter see if we can skip 238 * one or more entire sub-trees. If we can we 239 * return the internal mode and the caller processes 240 * the skipped range (see mirror_read) 241 */ 242 if (cursor->flags & HAMMER_CURSOR_MIRROR_FILTERED) { 243 if (elm->internal.mirror_tid < 244 cursor->cmirror->mirror_tid) { 245 hammer_cursor_mirror_filter(cursor); 246 return(0); 247 } 248 } 249 250 error = hammer_cursor_down(cursor); 251 if (error) 252 break; 253 KKASSERT(cursor->index == 0); 254 /* reload stale pointer */ 255 node = cursor->node->ondisk; 256 continue; 257 } else { 258 elm = &node->elms[cursor->index]; 259 r = hammer_btree_cmp(&cursor->key_end, &elm->base); 260 if (hammer_debug_btree) { 261 kprintf("ELEMENT %016llx:%d %c %016llx %02x %016llx lo=%02x %d\n", 262 cursor->node->node_offset, 263 cursor->index, 264 (elm[0].leaf.base.btype ? 265 elm[0].leaf.base.btype : '?'), 266 elm[0].leaf.base.obj_id, 267 elm[0].leaf.base.rec_type, 268 elm[0].leaf.base.key, 269 elm[0].leaf.base.localization, 270 r 271 ); 272 } 273 if (r < 0) { 274 error = ENOENT; 275 break; 276 } 277 278 /* 279 * We support both end-inclusive and 280 * end-exclusive searches. 281 */ 282 if (r == 0 && 283 (cursor->flags & HAMMER_CURSOR_END_INCLUSIVE) == 0) { 284 error = ENOENT; 285 break; 286 } 287 288 switch(elm->leaf.base.btype) { 289 case HAMMER_BTREE_TYPE_RECORD: 290 if ((cursor->flags & HAMMER_CURSOR_ASOF) && 291 hammer_btree_chkts(cursor->asof, &elm->base)) { 292 ++cursor->index; 293 continue; 294 } 295 error = 0; 296 break; 297 default: 298 error = EINVAL; 299 break; 300 } 301 if (error) 302 break; 303 } 304 /* 305 * node pointer invalid after loop 306 */ 307 308 /* 309 * Return entry 310 */ 311 if (hammer_debug_btree) { 312 int i = cursor->index; 313 hammer_btree_elm_t elm = &cursor->node->ondisk->elms[i]; 314 kprintf("ITERATE %p:%d %016llx %02x %016llx lo=%02x\n", 315 cursor->node, i, 316 elm->internal.base.obj_id, 317 elm->internal.base.rec_type, 318 elm->internal.base.key, 319 elm->internal.base.localization 320 ); 321 } 322 return(0); 323 } 324 return(error); 325 } 326 327 /* 328 * We hit an internal element that we could skip as part of a mirroring 329 * scan. Calculate the entire range being skipped. 330 * 331 * It is important to include any gaps between the parent's left_bound 332 * and the node's left_bound, and same goes for the right side. 333 */ 334 static void 335 hammer_cursor_mirror_filter(hammer_cursor_t cursor) 336 { 337 struct hammer_cmirror *cmirror; 338 hammer_node_ondisk_t ondisk; 339 hammer_btree_elm_t elm; 340 341 ondisk = cursor->node->ondisk; 342 cmirror = cursor->cmirror; 343 344 /* 345 * Calculate the skipped range 346 */ 347 elm = &ondisk->elms[cursor->index]; 348 if (cursor->index == 0) 349 cmirror->skip_beg = *cursor->left_bound; 350 else 351 cmirror->skip_beg = elm->internal.base; 352 while (cursor->index < ondisk->count) { 353 if (elm->internal.mirror_tid >= cmirror->mirror_tid) 354 break; 355 ++cursor->index; 356 ++elm; 357 } 358 if (cursor->index == ondisk->count) 359 cmirror->skip_end = *cursor->right_bound; 360 else 361 cmirror->skip_end = elm->internal.base; 362 363 /* 364 * clip the returned result. 365 */ 366 if (hammer_btree_cmp(&cmirror->skip_beg, &cursor->key_beg) < 0) 367 cmirror->skip_beg = cursor->key_beg; 368 if (hammer_btree_cmp(&cmirror->skip_end, &cursor->key_end) > 0) 369 cmirror->skip_end = cursor->key_end; 370 } 371 372 /* 373 * Iterate in the reverse direction. This is used by the pruning code to 374 * avoid overlapping records. 375 */ 376 int 377 hammer_btree_iterate_reverse(hammer_cursor_t cursor) 378 { 379 hammer_node_ondisk_t node; 380 hammer_btree_elm_t elm; 381 int error = 0; 382 int r; 383 int s; 384 385 /* mirror filtering not supported for reverse iteration */ 386 KKASSERT ((cursor->flags & HAMMER_CURSOR_MIRROR_FILTERED) == 0); 387 388 /* 389 * Skip past the current record. For various reasons the cursor 390 * may end up set to -1 or set to point at the end of the current 391 * node. These cases must be addressed. 392 */ 393 node = cursor->node->ondisk; 394 if (node == NULL) 395 return(ENOENT); 396 if (cursor->index != -1 && 397 (cursor->flags & HAMMER_CURSOR_ATEDISK)) { 398 --cursor->index; 399 } 400 if (cursor->index == cursor->node->ondisk->count) 401 --cursor->index; 402 403 /* 404 * Loop until an element is found or we are done. 405 */ 406 for (;;) { 407 ++hammer_stats_btree_iterations; 408 hammer_flusher_clean_loose_ios(cursor->trans->hmp); 409 410 /* 411 * We iterate up the tree and then index over one element 412 * while we are at the last element in the current node. 413 */ 414 if (cursor->index == -1) { 415 error = hammer_cursor_up(cursor); 416 if (error) { 417 cursor->index = 0; /* sanity */ 418 break; 419 } 420 /* reload stale pointer */ 421 node = cursor->node->ondisk; 422 KKASSERT(cursor->index != node->count); 423 --cursor->index; 424 continue; 425 } 426 427 /* 428 * Check internal or leaf element. Determine if the record 429 * at the cursor has gone beyond the end of our range. 430 * 431 * We recurse down through internal nodes. 432 */ 433 KKASSERT(cursor->index != node->count); 434 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) { 435 elm = &node->elms[cursor->index]; 436 r = hammer_btree_cmp(&cursor->key_end, &elm[0].base); 437 s = hammer_btree_cmp(&cursor->key_beg, &elm[1].base); 438 if (hammer_debug_btree) { 439 kprintf("BRACKETL %016llx[%d] %016llx %02x %016llx lo=%02x %d\n", 440 cursor->node->node_offset, 441 cursor->index, 442 elm[0].internal.base.obj_id, 443 elm[0].internal.base.rec_type, 444 elm[0].internal.base.key, 445 elm[0].internal.base.localization, 446 r 447 ); 448 kprintf("BRACKETR %016llx[%d] %016llx %02x %016llx lo=%02x %d\n", 449 cursor->node->node_offset, 450 cursor->index + 1, 451 elm[1].internal.base.obj_id, 452 elm[1].internal.base.rec_type, 453 elm[1].internal.base.key, 454 elm[1].internal.base.localization, 455 s 456 ); 457 } 458 459 if (s >= 0) { 460 error = ENOENT; 461 break; 462 } 463 KKASSERT(r >= 0); 464 465 /* 466 * Better not be zero 467 */ 468 KKASSERT(elm->internal.subtree_offset != 0); 469 470 error = hammer_cursor_down(cursor); 471 if (error) 472 break; 473 KKASSERT(cursor->index == 0); 474 /* reload stale pointer */ 475 node = cursor->node->ondisk; 476 477 /* this can assign -1 if the leaf was empty */ 478 cursor->index = node->count - 1; 479 continue; 480 } else { 481 elm = &node->elms[cursor->index]; 482 s = hammer_btree_cmp(&cursor->key_beg, &elm->base); 483 if (hammer_debug_btree) { 484 kprintf("ELEMENT %016llx:%d %c %016llx %02x %016llx lo=%02x %d\n", 485 cursor->node->node_offset, 486 cursor->index, 487 (elm[0].leaf.base.btype ? 488 elm[0].leaf.base.btype : '?'), 489 elm[0].leaf.base.obj_id, 490 elm[0].leaf.base.rec_type, 491 elm[0].leaf.base.key, 492 elm[0].leaf.base.localization, 493 s 494 ); 495 } 496 if (s > 0) { 497 error = ENOENT; 498 break; 499 } 500 501 switch(elm->leaf.base.btype) { 502 case HAMMER_BTREE_TYPE_RECORD: 503 if ((cursor->flags & HAMMER_CURSOR_ASOF) && 504 hammer_btree_chkts(cursor->asof, &elm->base)) { 505 --cursor->index; 506 continue; 507 } 508 error = 0; 509 break; 510 default: 511 error = EINVAL; 512 break; 513 } 514 if (error) 515 break; 516 } 517 /* 518 * node pointer invalid after loop 519 */ 520 521 /* 522 * Return entry 523 */ 524 if (hammer_debug_btree) { 525 int i = cursor->index; 526 hammer_btree_elm_t elm = &cursor->node->ondisk->elms[i]; 527 kprintf("ITERATE %p:%d %016llx %02x %016llx lo=%02x\n", 528 cursor->node, i, 529 elm->internal.base.obj_id, 530 elm->internal.base.rec_type, 531 elm->internal.base.key, 532 elm->internal.base.localization 533 ); 534 } 535 return(0); 536 } 537 return(error); 538 } 539 540 /* 541 * Lookup cursor->key_beg. 0 is returned on success, ENOENT if the entry 542 * could not be found, EDEADLK if inserting and a retry is needed, and a 543 * fatal error otherwise. When retrying, the caller must terminate the 544 * cursor and reinitialize it. EDEADLK cannot be returned if not inserting. 545 * 546 * The cursor is suitably positioned for a deletion on success, and suitably 547 * positioned for an insertion on ENOENT if HAMMER_CURSOR_INSERT was 548 * specified. 549 * 550 * The cursor may begin anywhere, the search will traverse the tree in 551 * either direction to locate the requested element. 552 * 553 * Most of the logic implementing historical searches is handled here. We 554 * do an initial lookup with create_tid set to the asof TID. Due to the 555 * way records are laid out, a backwards iteration may be required if 556 * ENOENT is returned to locate the historical record. Here's the 557 * problem: 558 * 559 * create_tid: 10 15 20 560 * LEAF1 LEAF2 561 * records: (11) (18) 562 * 563 * Lets say we want to do a lookup AS-OF timestamp 17. We will traverse 564 * LEAF2 but the only record in LEAF2 has a create_tid of 18, which is 565 * not visible and thus causes ENOENT to be returned. We really need 566 * to check record 11 in LEAF1. If it also fails then the search fails 567 * (e.g. it might represent the range 11-16 and thus still not match our 568 * AS-OF timestamp of 17). Note that LEAF1 could be empty, requiring 569 * further iterations. 570 * 571 * If this case occurs btree_search() will set HAMMER_CURSOR_CREATE_CHECK 572 * and the cursor->create_check TID if an iteration might be needed. 573 * In the above example create_check would be set to 14. 574 */ 575 int 576 hammer_btree_lookup(hammer_cursor_t cursor) 577 { 578 int error; 579 580 KKASSERT ((cursor->flags & HAMMER_CURSOR_INSERT) == 0 || 581 cursor->trans->sync_lock_refs > 0); 582 ++hammer_stats_btree_lookups; 583 if (cursor->flags & HAMMER_CURSOR_ASOF) { 584 KKASSERT((cursor->flags & HAMMER_CURSOR_INSERT) == 0); 585 cursor->key_beg.create_tid = cursor->asof; 586 for (;;) { 587 cursor->flags &= ~HAMMER_CURSOR_CREATE_CHECK; 588 error = btree_search(cursor, 0); 589 if (error != ENOENT || 590 (cursor->flags & HAMMER_CURSOR_CREATE_CHECK) == 0) { 591 /* 592 * Stop if no error. 593 * Stop if error other then ENOENT. 594 * Stop if ENOENT and not special case. 595 */ 596 break; 597 } 598 if (hammer_debug_btree) { 599 kprintf("CREATE_CHECK %016llx\n", 600 cursor->create_check); 601 } 602 cursor->key_beg.create_tid = cursor->create_check; 603 /* loop */ 604 } 605 } else { 606 error = btree_search(cursor, 0); 607 } 608 if (error == 0) 609 error = hammer_btree_extract(cursor, cursor->flags); 610 return(error); 611 } 612 613 /* 614 * Execute the logic required to start an iteration. The first record 615 * located within the specified range is returned and iteration control 616 * flags are adjusted for successive hammer_btree_iterate() calls. 617 */ 618 int 619 hammer_btree_first(hammer_cursor_t cursor) 620 { 621 int error; 622 623 error = hammer_btree_lookup(cursor); 624 if (error == ENOENT) { 625 cursor->flags &= ~HAMMER_CURSOR_ATEDISK; 626 error = hammer_btree_iterate(cursor); 627 } 628 cursor->flags |= HAMMER_CURSOR_ATEDISK; 629 return(error); 630 } 631 632 /* 633 * Similarly but for an iteration in the reverse direction. 634 * 635 * Set ATEDISK when iterating backwards to skip the current entry, 636 * which after an ENOENT lookup will be pointing beyond our end point. 637 */ 638 int 639 hammer_btree_last(hammer_cursor_t cursor) 640 { 641 struct hammer_base_elm save; 642 int error; 643 644 save = cursor->key_beg; 645 cursor->key_beg = cursor->key_end; 646 error = hammer_btree_lookup(cursor); 647 cursor->key_beg = save; 648 if (error == ENOENT || 649 (cursor->flags & HAMMER_CURSOR_END_INCLUSIVE) == 0) { 650 cursor->flags |= HAMMER_CURSOR_ATEDISK; 651 error = hammer_btree_iterate_reverse(cursor); 652 } 653 cursor->flags |= HAMMER_CURSOR_ATEDISK; 654 return(error); 655 } 656 657 /* 658 * Extract the record and/or data associated with the cursor's current 659 * position. Any prior record or data stored in the cursor is replaced. 660 * The cursor must be positioned at a leaf node. 661 * 662 * NOTE: All extractions occur at the leaf of the B-Tree. 663 */ 664 int 665 hammer_btree_extract(hammer_cursor_t cursor, int flags) 666 { 667 hammer_node_ondisk_t node; 668 hammer_btree_elm_t elm; 669 hammer_off_t data_off; 670 hammer_mount_t hmp; 671 int32_t data_len; 672 int error; 673 674 /* 675 * The case where the data reference resolves to the same buffer 676 * as the record reference must be handled. 677 */ 678 node = cursor->node->ondisk; 679 elm = &node->elms[cursor->index]; 680 cursor->data = NULL; 681 hmp = cursor->node->hmp; 682 683 /* 684 * There is nothing to extract for an internal element. 685 */ 686 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) 687 return(EINVAL); 688 689 /* 690 * Only record types have data. 691 */ 692 KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF); 693 cursor->leaf = &elm->leaf; 694 695 if ((flags & HAMMER_CURSOR_GET_DATA) == 0) 696 return(0); 697 if (elm->leaf.base.btype != HAMMER_BTREE_TYPE_RECORD) 698 return(0); 699 data_off = elm->leaf.data_offset; 700 data_len = elm->leaf.data_len; 701 if (data_off == 0) 702 return(0); 703 704 /* 705 * Load the data 706 */ 707 KKASSERT(data_len >= 0 && data_len <= HAMMER_XBUFSIZE); 708 cursor->data = hammer_bread_ext(hmp, data_off, data_len, 709 &error, &cursor->data_buffer); 710 if (hammer_crc_test_leaf(cursor->data, &elm->leaf) == 0) { 711 kprintf("CRC DATA @ %016llx/%d FAILED\n", 712 elm->leaf.data_offset, elm->leaf.data_len); 713 Debugger("CRC FAILED: DATA"); 714 } 715 return(error); 716 } 717 718 719 /* 720 * Insert a leaf element into the B-Tree at the current cursor position. 721 * The cursor is positioned such that the element at and beyond the cursor 722 * are shifted to make room for the new record. 723 * 724 * The caller must call hammer_btree_lookup() with the HAMMER_CURSOR_INSERT 725 * flag set and that call must return ENOENT before this function can be 726 * called. 727 * 728 * The caller may depend on the cursor's exclusive lock after return to 729 * interlock frontend visibility (see HAMMER_RECF_CONVERT_DELETE). 730 * 731 * ENOSPC is returned if there is no room to insert a new record. 732 */ 733 int 734 hammer_btree_insert(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm, 735 int *doprop) 736 { 737 hammer_node_ondisk_t node; 738 int i; 739 int error; 740 741 *doprop = 0; 742 if ((error = hammer_cursor_upgrade_node(cursor)) != 0) 743 return(error); 744 ++hammer_stats_btree_inserts; 745 746 /* 747 * Insert the element at the leaf node and update the count in the 748 * parent. It is possible for parent to be NULL, indicating that 749 * the filesystem's ROOT B-Tree node is a leaf itself, which is 750 * possible. The root inode can never be deleted so the leaf should 751 * never be empty. 752 * 753 * Remember that the right-hand boundary is not included in the 754 * count. 755 */ 756 hammer_modify_node_all(cursor->trans, cursor->node); 757 node = cursor->node->ondisk; 758 i = cursor->index; 759 KKASSERT(elm->base.btype != 0); 760 KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF); 761 KKASSERT(node->count < HAMMER_BTREE_LEAF_ELMS); 762 if (i != node->count) { 763 bcopy(&node->elms[i], &node->elms[i+1], 764 (node->count - i) * sizeof(*elm)); 765 } 766 node->elms[i].leaf = *elm; 767 ++node->count; 768 hammer_cursor_inserted_element(cursor->node, i); 769 770 /* 771 * Update the leaf node's aggregate mirror_tid for mirroring 772 * support. 773 */ 774 if (node->mirror_tid < elm->base.delete_tid) { 775 node->mirror_tid = elm->base.delete_tid; 776 *doprop = 1; 777 } 778 if (node->mirror_tid < elm->base.create_tid) { 779 node->mirror_tid = elm->base.create_tid; 780 *doprop = 1; 781 } 782 hammer_modify_node_done(cursor->node); 783 784 /* 785 * Debugging sanity checks. 786 */ 787 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->base) <= 0); 788 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->base) > 0); 789 if (i) { 790 KKASSERT(hammer_btree_cmp(&node->elms[i-1].leaf.base, &elm->base) < 0); 791 } 792 if (i != node->count - 1) 793 KKASSERT(hammer_btree_cmp(&node->elms[i+1].leaf.base, &elm->base) > 0); 794 795 return(0); 796 } 797 798 /* 799 * Delete a record from the B-Tree at the current cursor position. 800 * The cursor is positioned such that the current element is the one 801 * to be deleted. 802 * 803 * On return the cursor will be positioned after the deleted element and 804 * MAY point to an internal node. It will be suitable for the continuation 805 * of an iteration but not for an insertion or deletion. 806 * 807 * Deletions will attempt to partially rebalance the B-Tree in an upward 808 * direction, but will terminate rather then deadlock. Empty internal nodes 809 * are never allowed by a deletion which deadlocks may end up giving us an 810 * empty leaf. The pruner will clean up and rebalance the tree. 811 * 812 * This function can return EDEADLK, requiring the caller to retry the 813 * operation after clearing the deadlock. 814 */ 815 int 816 hammer_btree_delete(hammer_cursor_t cursor) 817 { 818 hammer_node_ondisk_t ondisk; 819 hammer_node_t node; 820 hammer_node_t parent; 821 int error; 822 int i; 823 824 KKASSERT (cursor->trans->sync_lock_refs > 0); 825 if ((error = hammer_cursor_upgrade(cursor)) != 0) 826 return(error); 827 ++hammer_stats_btree_deletes; 828 829 /* 830 * Delete the element from the leaf node. 831 * 832 * Remember that leaf nodes do not have boundaries. 833 */ 834 node = cursor->node; 835 ondisk = node->ondisk; 836 i = cursor->index; 837 838 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_LEAF); 839 KKASSERT(i >= 0 && i < ondisk->count); 840 hammer_modify_node_all(cursor->trans, node); 841 if (i + 1 != ondisk->count) { 842 bcopy(&ondisk->elms[i+1], &ondisk->elms[i], 843 (ondisk->count - i - 1) * sizeof(ondisk->elms[0])); 844 } 845 --ondisk->count; 846 hammer_modify_node_done(node); 847 hammer_cursor_deleted_element(node, i); 848 849 /* 850 * Validate local parent 851 */ 852 if (ondisk->parent) { 853 parent = cursor->parent; 854 855 KKASSERT(parent != NULL); 856 KKASSERT(parent->node_offset == ondisk->parent); 857 } 858 859 /* 860 * If the leaf becomes empty it must be detached from the parent, 861 * potentially recursing through to the filesystem root. 862 * 863 * This may reposition the cursor at one of the parent's of the 864 * current node. 865 * 866 * Ignore deadlock errors, that simply means that btree_remove 867 * was unable to recurse and had to leave us with an empty leaf. 868 */ 869 KKASSERT(cursor->index <= ondisk->count); 870 if (ondisk->count == 0) { 871 error = btree_remove(cursor); 872 if (error == EDEADLK) 873 error = 0; 874 } else { 875 error = 0; 876 } 877 KKASSERT(cursor->parent == NULL || 878 cursor->parent_index < cursor->parent->ondisk->count); 879 return(error); 880 } 881 882 /* 883 * PRIMAY B-TREE SEARCH SUPPORT PROCEDURE 884 * 885 * Search the filesystem B-Tree for cursor->key_beg, return the matching node. 886 * 887 * The search can begin ANYWHERE in the B-Tree. As a first step the search 888 * iterates up the tree as necessary to properly position itself prior to 889 * actually doing the sarch. 890 * 891 * INSERTIONS: The search will split full nodes and leaves on its way down 892 * and guarentee that the leaf it ends up on is not full. If we run out 893 * of space the search continues to the leaf (to position the cursor for 894 * the spike), but ENOSPC is returned. 895 * 896 * The search is only guarenteed to end up on a leaf if an error code of 0 897 * is returned, or if inserting and an error code of ENOENT is returned. 898 * Otherwise it can stop at an internal node. On success a search returns 899 * a leaf node. 900 * 901 * COMPLEXITY WARNING! This is the core B-Tree search code for the entire 902 * filesystem, and it is not simple code. Please note the following facts: 903 * 904 * - Internal node recursions have a boundary on the left AND right. The 905 * right boundary is non-inclusive. The create_tid is a generic part 906 * of the key for internal nodes. 907 * 908 * - Leaf nodes contain terminal elements only now. 909 * 910 * - Filesystem lookups typically set HAMMER_CURSOR_ASOF, indicating a 911 * historical search. ASOF and INSERT are mutually exclusive. When 912 * doing an as-of lookup btree_search() checks for a right-edge boundary 913 * case. If while recursing down the left-edge differs from the key 914 * by ONLY its create_tid, HAMMER_CURSOR_CREATE_CHECK is set along 915 * with cursor->create_check. This is used by btree_lookup() to iterate. 916 * The iteration backwards because as-of searches can wind up going 917 * down the wrong branch of the B-Tree. 918 */ 919 static 920 int 921 btree_search(hammer_cursor_t cursor, int flags) 922 { 923 hammer_node_ondisk_t node; 924 hammer_btree_elm_t elm; 925 int error; 926 int enospc = 0; 927 int i; 928 int r; 929 int s; 930 931 flags |= cursor->flags; 932 ++hammer_stats_btree_searches; 933 934 if (hammer_debug_btree) { 935 kprintf("SEARCH %016llx[%d] %016llx %02x key=%016llx cre=%016llx lo=%02x (td = %p)\n", 936 cursor->node->node_offset, 937 cursor->index, 938 cursor->key_beg.obj_id, 939 cursor->key_beg.rec_type, 940 cursor->key_beg.key, 941 cursor->key_beg.create_tid, 942 cursor->key_beg.localization, 943 curthread 944 ); 945 if (cursor->parent) 946 kprintf("SEARCHP %016llx[%d] (%016llx/%016llx %016llx/%016llx) (%p/%p %p/%p)\n", 947 cursor->parent->node_offset, cursor->parent_index, 948 cursor->left_bound->obj_id, 949 cursor->parent->ondisk->elms[cursor->parent_index].internal.base.obj_id, 950 cursor->right_bound->obj_id, 951 cursor->parent->ondisk->elms[cursor->parent_index+1].internal.base.obj_id, 952 cursor->left_bound, 953 &cursor->parent->ondisk->elms[cursor->parent_index], 954 cursor->right_bound, 955 &cursor->parent->ondisk->elms[cursor->parent_index+1] 956 ); 957 } 958 959 /* 960 * Move our cursor up the tree until we find a node whos range covers 961 * the key we are trying to locate. 962 * 963 * The left bound is inclusive, the right bound is non-inclusive. 964 * It is ok to cursor up too far. 965 */ 966 for (;;) { 967 r = hammer_btree_cmp(&cursor->key_beg, cursor->left_bound); 968 s = hammer_btree_cmp(&cursor->key_beg, cursor->right_bound); 969 if (r >= 0 && s < 0) 970 break; 971 KKASSERT(cursor->parent); 972 ++hammer_stats_btree_iterations; 973 error = hammer_cursor_up(cursor); 974 if (error) 975 goto done; 976 } 977 978 /* 979 * The delete-checks below are based on node, not parent. Set the 980 * initial delete-check based on the parent. 981 */ 982 if (r == 1) { 983 KKASSERT(cursor->left_bound->create_tid != 1); 984 cursor->create_check = cursor->left_bound->create_tid - 1; 985 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK; 986 } 987 988 /* 989 * We better have ended up with a node somewhere. 990 */ 991 KKASSERT(cursor->node != NULL); 992 993 /* 994 * If we are inserting we can't start at a full node if the parent 995 * is also full (because there is no way to split the node), 996 * continue running up the tree until the requirement is satisfied 997 * or we hit the root of the filesystem. 998 * 999 * (If inserting we aren't doing an as-of search so we don't have 1000 * to worry about create_check). 1001 */ 1002 while ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) { 1003 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 1004 if (btree_node_is_full(cursor->node->ondisk) == 0) 1005 break; 1006 } else { 1007 if (btree_node_is_full(cursor->node->ondisk) ==0) 1008 break; 1009 } 1010 if (cursor->node->ondisk->parent == 0 || 1011 cursor->parent->ondisk->count != HAMMER_BTREE_INT_ELMS) { 1012 break; 1013 } 1014 ++hammer_stats_btree_iterations; 1015 error = hammer_cursor_up(cursor); 1016 /* node may have become stale */ 1017 if (error) 1018 goto done; 1019 } 1020 1021 /* 1022 * Push down through internal nodes to locate the requested key. 1023 */ 1024 node = cursor->node->ondisk; 1025 while (node->type == HAMMER_BTREE_TYPE_INTERNAL) { 1026 /* 1027 * Scan the node to find the subtree index to push down into. 1028 * We go one-past, then back-up. 1029 * 1030 * We must proactively remove deleted elements which may 1031 * have been left over from a deadlocked btree_remove(). 1032 * 1033 * The left and right boundaries are included in the loop 1034 * in order to detect edge cases. 1035 * 1036 * If the separator only differs by create_tid (r == 1) 1037 * and we are doing an as-of search, we may end up going 1038 * down a branch to the left of the one containing the 1039 * desired key. This requires numerous special cases. 1040 */ 1041 ++hammer_stats_btree_iterations; 1042 if (hammer_debug_btree) { 1043 kprintf("SEARCH-I %016llx count=%d\n", 1044 cursor->node->node_offset, 1045 node->count); 1046 } 1047 1048 /* 1049 * Try to shortcut the search before dropping into the 1050 * linear loop. Locate the first node where r <= 1. 1051 */ 1052 i = hammer_btree_search_node(&cursor->key_beg, node); 1053 while (i <= node->count) { 1054 ++hammer_stats_btree_elements; 1055 elm = &node->elms[i]; 1056 r = hammer_btree_cmp(&cursor->key_beg, &elm->base); 1057 if (hammer_debug_btree > 2) { 1058 kprintf(" IELM %p %d r=%d\n", 1059 &node->elms[i], i, r); 1060 } 1061 if (r < 0) 1062 break; 1063 if (r == 1) { 1064 KKASSERT(elm->base.create_tid != 1); 1065 cursor->create_check = elm->base.create_tid - 1; 1066 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK; 1067 } 1068 ++i; 1069 } 1070 if (hammer_debug_btree) { 1071 kprintf("SEARCH-I preI=%d/%d r=%d\n", 1072 i, node->count, r); 1073 } 1074 1075 /* 1076 * These cases occur when the parent's idea of the boundary 1077 * is wider then the child's idea of the boundary, and 1078 * require special handling. If not inserting we can 1079 * terminate the search early for these cases but the 1080 * child's boundaries cannot be unconditionally modified. 1081 */ 1082 if (i == 0) { 1083 /* 1084 * If i == 0 the search terminated to the LEFT of the 1085 * left_boundary but to the RIGHT of the parent's left 1086 * boundary. 1087 */ 1088 u_int8_t save; 1089 1090 elm = &node->elms[0]; 1091 1092 /* 1093 * If we aren't inserting we can stop here. 1094 */ 1095 if ((flags & (HAMMER_CURSOR_INSERT | 1096 HAMMER_CURSOR_PRUNING)) == 0) { 1097 cursor->index = 0; 1098 return(ENOENT); 1099 } 1100 1101 /* 1102 * Correct a left-hand boundary mismatch. 1103 * 1104 * We can only do this if we can upgrade the lock, 1105 * and synchronized as a background cursor (i.e. 1106 * inserting or pruning). 1107 * 1108 * WARNING: We can only do this if inserting, i.e. 1109 * we are running on the backend. 1110 */ 1111 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1112 return(error); 1113 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND); 1114 hammer_modify_node_field(cursor->trans, cursor->node, 1115 elms[0]); 1116 save = node->elms[0].base.btype; 1117 node->elms[0].base = *cursor->left_bound; 1118 node->elms[0].base.btype = save; 1119 hammer_modify_node_done(cursor->node); 1120 } else if (i == node->count + 1) { 1121 /* 1122 * If i == node->count + 1 the search terminated to 1123 * the RIGHT of the right boundary but to the LEFT 1124 * of the parent's right boundary. If we aren't 1125 * inserting we can stop here. 1126 * 1127 * Note that the last element in this case is 1128 * elms[i-2] prior to adjustments to 'i'. 1129 */ 1130 --i; 1131 if ((flags & (HAMMER_CURSOR_INSERT | 1132 HAMMER_CURSOR_PRUNING)) == 0) { 1133 cursor->index = i; 1134 return (ENOENT); 1135 } 1136 1137 /* 1138 * Correct a right-hand boundary mismatch. 1139 * (actual push-down record is i-2 prior to 1140 * adjustments to i). 1141 * 1142 * We can only do this if we can upgrade the lock, 1143 * and synchronized as a background cursor (i.e. 1144 * inserting or pruning). 1145 * 1146 * WARNING: We can only do this if inserting, i.e. 1147 * we are running on the backend. 1148 */ 1149 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1150 return(error); 1151 elm = &node->elms[i]; 1152 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND); 1153 hammer_modify_node(cursor->trans, cursor->node, 1154 &elm->base, sizeof(elm->base)); 1155 elm->base = *cursor->right_bound; 1156 hammer_modify_node_done(cursor->node); 1157 --i; 1158 } else { 1159 /* 1160 * The push-down index is now i - 1. If we had 1161 * terminated on the right boundary this will point 1162 * us at the last element. 1163 */ 1164 --i; 1165 } 1166 cursor->index = i; 1167 elm = &node->elms[i]; 1168 1169 if (hammer_debug_btree) { 1170 kprintf("RESULT-I %016llx[%d] %016llx %02x " 1171 "key=%016llx cre=%016llx lo=%02x\n", 1172 cursor->node->node_offset, 1173 i, 1174 elm->internal.base.obj_id, 1175 elm->internal.base.rec_type, 1176 elm->internal.base.key, 1177 elm->internal.base.create_tid, 1178 elm->internal.base.localization 1179 ); 1180 } 1181 1182 /* 1183 * We better have a valid subtree offset. 1184 */ 1185 KKASSERT(elm->internal.subtree_offset != 0); 1186 1187 /* 1188 * Handle insertion and deletion requirements. 1189 * 1190 * If inserting split full nodes. The split code will 1191 * adjust cursor->node and cursor->index if the current 1192 * index winds up in the new node. 1193 * 1194 * If inserting and a left or right edge case was detected, 1195 * we cannot correct the left or right boundary and must 1196 * prepend and append an empty leaf node in order to make 1197 * the boundary correction. 1198 * 1199 * If we run out of space we set enospc and continue on 1200 * to a leaf to provide the spike code with a good point 1201 * of entry. 1202 */ 1203 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) { 1204 if (btree_node_is_full(node)) { 1205 error = btree_split_internal(cursor); 1206 if (error) { 1207 if (error != ENOSPC) 1208 goto done; 1209 enospc = 1; 1210 } 1211 /* 1212 * reload stale pointers 1213 */ 1214 i = cursor->index; 1215 node = cursor->node->ondisk; 1216 } 1217 } 1218 1219 /* 1220 * Push down (push into new node, existing node becomes 1221 * the parent) and continue the search. 1222 */ 1223 error = hammer_cursor_down(cursor); 1224 /* node may have become stale */ 1225 if (error) 1226 goto done; 1227 node = cursor->node->ondisk; 1228 } 1229 1230 /* 1231 * We are at a leaf, do a linear search of the key array. 1232 * 1233 * On success the index is set to the matching element and 0 1234 * is returned. 1235 * 1236 * On failure the index is set to the insertion point and ENOENT 1237 * is returned. 1238 * 1239 * Boundaries are not stored in leaf nodes, so the index can wind 1240 * up to the left of element 0 (index == 0) or past the end of 1241 * the array (index == node->count). It is also possible that the 1242 * leaf might be empty. 1243 */ 1244 ++hammer_stats_btree_iterations; 1245 KKASSERT (node->type == HAMMER_BTREE_TYPE_LEAF); 1246 KKASSERT(node->count <= HAMMER_BTREE_LEAF_ELMS); 1247 if (hammer_debug_btree) { 1248 kprintf("SEARCH-L %016llx count=%d\n", 1249 cursor->node->node_offset, 1250 node->count); 1251 } 1252 1253 /* 1254 * Try to shortcut the search before dropping into the 1255 * linear loop. Locate the first node where r <= 1. 1256 */ 1257 i = hammer_btree_search_node(&cursor->key_beg, node); 1258 while (i < node->count) { 1259 ++hammer_stats_btree_elements; 1260 elm = &node->elms[i]; 1261 1262 r = hammer_btree_cmp(&cursor->key_beg, &elm->leaf.base); 1263 1264 if (hammer_debug_btree > 1) 1265 kprintf(" ELM %p %d r=%d\n", &node->elms[i], i, r); 1266 1267 /* 1268 * We are at a record element. Stop if we've flipped past 1269 * key_beg, not counting the create_tid test. Allow the 1270 * r == 1 case (key_beg > element but differs only by its 1271 * create_tid) to fall through to the AS-OF check. 1272 */ 1273 KKASSERT (elm->leaf.base.btype == HAMMER_BTREE_TYPE_RECORD); 1274 1275 if (r < 0) 1276 goto failed; 1277 if (r > 1) { 1278 ++i; 1279 continue; 1280 } 1281 1282 /* 1283 * Check our as-of timestamp against the element. 1284 */ 1285 if (flags & HAMMER_CURSOR_ASOF) { 1286 if (hammer_btree_chkts(cursor->asof, 1287 &node->elms[i].base) != 0) { 1288 ++i; 1289 continue; 1290 } 1291 /* success */ 1292 } else { 1293 if (r > 0) { /* can only be +1 */ 1294 ++i; 1295 continue; 1296 } 1297 /* success */ 1298 } 1299 cursor->index = i; 1300 error = 0; 1301 if (hammer_debug_btree) { 1302 kprintf("RESULT-L %016llx[%d] (SUCCESS)\n", 1303 cursor->node->node_offset, i); 1304 } 1305 goto done; 1306 } 1307 1308 /* 1309 * The search of the leaf node failed. i is the insertion point. 1310 */ 1311 failed: 1312 if (hammer_debug_btree) { 1313 kprintf("RESULT-L %016llx[%d] (FAILED)\n", 1314 cursor->node->node_offset, i); 1315 } 1316 1317 /* 1318 * No exact match was found, i is now at the insertion point. 1319 * 1320 * If inserting split a full leaf before returning. This 1321 * may have the side effect of adjusting cursor->node and 1322 * cursor->index. 1323 */ 1324 cursor->index = i; 1325 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0 && 1326 btree_node_is_full(node)) { 1327 error = btree_split_leaf(cursor); 1328 if (error) { 1329 if (error != ENOSPC) 1330 goto done; 1331 enospc = 1; 1332 } 1333 /* 1334 * reload stale pointers 1335 */ 1336 /* NOT USED 1337 i = cursor->index; 1338 node = &cursor->node->internal; 1339 */ 1340 } 1341 1342 /* 1343 * We reached a leaf but did not find the key we were looking for. 1344 * If this is an insert we will be properly positioned for an insert 1345 * (ENOENT) or spike (ENOSPC) operation. 1346 */ 1347 error = enospc ? ENOSPC : ENOENT; 1348 done: 1349 return(error); 1350 } 1351 1352 /* 1353 * Heuristical search for the first element whos comparison is <= 1. May 1354 * return an index whos compare result is > 1 but may only return an index 1355 * whos compare result is <= 1 if it is the first element with that result. 1356 */ 1357 int 1358 hammer_btree_search_node(hammer_base_elm_t elm, hammer_node_ondisk_t node) 1359 { 1360 int b; 1361 int s; 1362 int i; 1363 int r; 1364 1365 /* 1366 * Don't bother if the node does not have very many elements 1367 */ 1368 b = 0; 1369 s = node->count; 1370 while (s - b > 4) { 1371 i = b + (s - b) / 2; 1372 ++hammer_stats_btree_elements; 1373 r = hammer_btree_cmp(elm, &node->elms[i].leaf.base); 1374 if (r <= 1) { 1375 s = i; 1376 } else { 1377 b = i; 1378 } 1379 } 1380 return(b); 1381 } 1382 1383 1384 /************************************************************************ 1385 * SPLITTING AND MERGING * 1386 ************************************************************************ 1387 * 1388 * These routines do all the dirty work required to split and merge nodes. 1389 */ 1390 1391 /* 1392 * Split an internal node into two nodes and move the separator at the split 1393 * point to the parent. 1394 * 1395 * (cursor->node, cursor->index) indicates the element the caller intends 1396 * to push into. We will adjust node and index if that element winds 1397 * up in the split node. 1398 * 1399 * If we are at the root of the filesystem a new root must be created with 1400 * two elements, one pointing to the original root and one pointing to the 1401 * newly allocated split node. 1402 */ 1403 static 1404 int 1405 btree_split_internal(hammer_cursor_t cursor) 1406 { 1407 hammer_node_ondisk_t ondisk; 1408 hammer_node_t node; 1409 hammer_node_t parent; 1410 hammer_node_t new_node; 1411 hammer_btree_elm_t elm; 1412 hammer_btree_elm_t parent_elm; 1413 struct hammer_node_lock lockroot; 1414 hammer_mount_t hmp = cursor->trans->hmp; 1415 int parent_index; 1416 int made_root; 1417 int split; 1418 int error; 1419 int i; 1420 const int esize = sizeof(*elm); 1421 1422 hammer_node_lock_init(&lockroot, cursor->node); 1423 error = hammer_btree_lock_children(cursor, 1, &lockroot); 1424 if (error) 1425 goto done; 1426 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1427 goto done; 1428 ++hammer_stats_btree_splits; 1429 1430 /* 1431 * We are splitting but elms[split] will be promoted to the parent, 1432 * leaving the right hand node with one less element. If the 1433 * insertion point will be on the left-hand side adjust the split 1434 * point to give the right hand side one additional node. 1435 */ 1436 node = cursor->node; 1437 ondisk = node->ondisk; 1438 split = (ondisk->count + 1) / 2; 1439 if (cursor->index <= split) 1440 --split; 1441 1442 /* 1443 * If we are at the root of the filesystem, create a new root node 1444 * with 1 element and split normally. Avoid making major 1445 * modifications until we know the whole operation will work. 1446 */ 1447 if (ondisk->parent == 0) { 1448 parent = hammer_alloc_btree(cursor->trans, &error); 1449 if (parent == NULL) 1450 goto done; 1451 hammer_lock_ex(&parent->lock); 1452 hammer_modify_node_noundo(cursor->trans, parent); 1453 ondisk = parent->ondisk; 1454 ondisk->count = 1; 1455 ondisk->parent = 0; 1456 ondisk->mirror_tid = node->ondisk->mirror_tid; 1457 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1458 ondisk->elms[0].base = hmp->root_btree_beg; 1459 ondisk->elms[0].base.btype = node->ondisk->type; 1460 ondisk->elms[0].internal.subtree_offset = node->node_offset; 1461 ondisk->elms[1].base = hmp->root_btree_end; 1462 hammer_modify_node_done(parent); 1463 /* ondisk->elms[1].base.btype - not used */ 1464 made_root = 1; 1465 parent_index = 0; /* index of current node in parent */ 1466 } else { 1467 made_root = 0; 1468 parent = cursor->parent; 1469 parent_index = cursor->parent_index; 1470 } 1471 1472 /* 1473 * Split node into new_node at the split point. 1474 * 1475 * B O O O P N N B <-- P = node->elms[split] 1476 * 0 1 2 3 4 5 6 <-- subtree indices 1477 * 1478 * x x P x x 1479 * s S S s 1480 * / \ 1481 * B O O O B B N N B <--- inner boundary points are 'P' 1482 * 0 1 2 3 4 5 6 1483 * 1484 */ 1485 new_node = hammer_alloc_btree(cursor->trans, &error); 1486 if (new_node == NULL) { 1487 if (made_root) { 1488 hammer_unlock(&parent->lock); 1489 hammer_delete_node(cursor->trans, parent); 1490 hammer_rel_node(parent); 1491 } 1492 goto done; 1493 } 1494 hammer_lock_ex(&new_node->lock); 1495 1496 /* 1497 * Create the new node. P becomes the left-hand boundary in the 1498 * new node. Copy the right-hand boundary as well. 1499 * 1500 * elm is the new separator. 1501 */ 1502 hammer_modify_node_noundo(cursor->trans, new_node); 1503 hammer_modify_node_all(cursor->trans, node); 1504 ondisk = node->ondisk; 1505 elm = &ondisk->elms[split]; 1506 bcopy(elm, &new_node->ondisk->elms[0], 1507 (ondisk->count - split + 1) * esize); 1508 new_node->ondisk->count = ondisk->count - split; 1509 new_node->ondisk->parent = parent->node_offset; 1510 new_node->ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1511 new_node->ondisk->mirror_tid = ondisk->mirror_tid; 1512 KKASSERT(ondisk->type == new_node->ondisk->type); 1513 hammer_cursor_split_node(node, new_node, split); 1514 1515 /* 1516 * Cleanup the original node. Elm (P) becomes the new boundary, 1517 * its subtree_offset was moved to the new node. If we had created 1518 * a new root its parent pointer may have changed. 1519 */ 1520 elm->internal.subtree_offset = 0; 1521 ondisk->count = split; 1522 1523 /* 1524 * Insert the separator into the parent, fixup the parent's 1525 * reference to the original node, and reference the new node. 1526 * The separator is P. 1527 * 1528 * Remember that base.count does not include the right-hand boundary. 1529 */ 1530 hammer_modify_node_all(cursor->trans, parent); 1531 ondisk = parent->ondisk; 1532 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS); 1533 parent_elm = &ondisk->elms[parent_index+1]; 1534 bcopy(parent_elm, parent_elm + 1, 1535 (ondisk->count - parent_index) * esize); 1536 parent_elm->internal.base = elm->base; /* separator P */ 1537 parent_elm->internal.base.btype = new_node->ondisk->type; 1538 parent_elm->internal.subtree_offset = new_node->node_offset; 1539 parent_elm->internal.mirror_tid = new_node->ondisk->mirror_tid; 1540 ++ondisk->count; 1541 hammer_modify_node_done(parent); 1542 hammer_cursor_inserted_element(parent, parent_index + 1); 1543 1544 /* 1545 * The children of new_node need their parent pointer set to new_node. 1546 * The children have already been locked by 1547 * hammer_btree_lock_children(). 1548 */ 1549 for (i = 0; i < new_node->ondisk->count; ++i) { 1550 elm = &new_node->ondisk->elms[i]; 1551 error = btree_set_parent(cursor->trans, new_node, elm); 1552 if (error) { 1553 panic("btree_split_internal: btree-fixup problem"); 1554 } 1555 } 1556 hammer_modify_node_done(new_node); 1557 1558 /* 1559 * The filesystem's root B-Tree pointer may have to be updated. 1560 */ 1561 if (made_root) { 1562 hammer_volume_t volume; 1563 1564 volume = hammer_get_root_volume(hmp, &error); 1565 KKASSERT(error == 0); 1566 1567 hammer_modify_volume_field(cursor->trans, volume, 1568 vol0_btree_root); 1569 volume->ondisk->vol0_btree_root = parent->node_offset; 1570 hammer_modify_volume_done(volume); 1571 node->ondisk->parent = parent->node_offset; 1572 if (cursor->parent) { 1573 hammer_unlock(&cursor->parent->lock); 1574 hammer_rel_node(cursor->parent); 1575 } 1576 cursor->parent = parent; /* lock'd and ref'd */ 1577 hammer_rel_volume(volume, 0); 1578 } 1579 hammer_modify_node_done(node); 1580 1581 /* 1582 * Ok, now adjust the cursor depending on which element the original 1583 * index was pointing at. If we are >= the split point the push node 1584 * is now in the new node. 1585 * 1586 * NOTE: If we are at the split point itself we cannot stay with the 1587 * original node because the push index will point at the right-hand 1588 * boundary, which is illegal. 1589 * 1590 * NOTE: The cursor's parent or parent_index must be adjusted for 1591 * the case where a new parent (new root) was created, and the case 1592 * where the cursor is now pointing at the split node. 1593 */ 1594 if (cursor->index >= split) { 1595 cursor->parent_index = parent_index + 1; 1596 cursor->index -= split; 1597 hammer_unlock(&cursor->node->lock); 1598 hammer_rel_node(cursor->node); 1599 cursor->node = new_node; /* locked and ref'd */ 1600 } else { 1601 cursor->parent_index = parent_index; 1602 hammer_unlock(&new_node->lock); 1603 hammer_rel_node(new_node); 1604 } 1605 1606 /* 1607 * Fixup left and right bounds 1608 */ 1609 parent_elm = &parent->ondisk->elms[cursor->parent_index]; 1610 cursor->left_bound = &parent_elm[0].internal.base; 1611 cursor->right_bound = &parent_elm[1].internal.base; 1612 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1613 &cursor->node->ondisk->elms[0].internal.base) <= 0); 1614 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1615 &cursor->node->ondisk->elms[cursor->node->ondisk->count].internal.base) >= 0); 1616 1617 done: 1618 hammer_btree_unlock_children(cursor, &lockroot); 1619 hammer_cursor_downgrade(cursor); 1620 return (error); 1621 } 1622 1623 /* 1624 * Same as the above, but splits a full leaf node. 1625 * 1626 * This function 1627 */ 1628 static 1629 int 1630 btree_split_leaf(hammer_cursor_t cursor) 1631 { 1632 hammer_node_ondisk_t ondisk; 1633 hammer_node_t parent; 1634 hammer_node_t leaf; 1635 hammer_mount_t hmp; 1636 hammer_node_t new_leaf; 1637 hammer_btree_elm_t elm; 1638 hammer_btree_elm_t parent_elm; 1639 hammer_base_elm_t mid_boundary; 1640 int parent_index; 1641 int made_root; 1642 int split; 1643 int error; 1644 const size_t esize = sizeof(*elm); 1645 1646 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1647 return(error); 1648 ++hammer_stats_btree_splits; 1649 1650 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1651 &cursor->node->ondisk->elms[0].leaf.base) <= 0); 1652 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1653 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0); 1654 1655 /* 1656 * Calculate the split point. If the insertion point will be on 1657 * the left-hand side adjust the split point to give the right 1658 * hand side one additional node. 1659 * 1660 * Spikes are made up of two leaf elements which cannot be 1661 * safely split. 1662 */ 1663 leaf = cursor->node; 1664 ondisk = leaf->ondisk; 1665 split = (ondisk->count + 1) / 2; 1666 if (cursor->index <= split) 1667 --split; 1668 error = 0; 1669 hmp = leaf->hmp; 1670 1671 elm = &ondisk->elms[split]; 1672 1673 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm[-1].leaf.base) <= 0); 1674 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->leaf.base) <= 0); 1675 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->leaf.base) > 0); 1676 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm[1].leaf.base) > 0); 1677 1678 /* 1679 * If we are at the root of the tree, create a new root node with 1680 * 1 element and split normally. Avoid making major modifications 1681 * until we know the whole operation will work. 1682 */ 1683 if (ondisk->parent == 0) { 1684 parent = hammer_alloc_btree(cursor->trans, &error); 1685 if (parent == NULL) 1686 goto done; 1687 hammer_lock_ex(&parent->lock); 1688 hammer_modify_node_noundo(cursor->trans, parent); 1689 ondisk = parent->ondisk; 1690 ondisk->count = 1; 1691 ondisk->parent = 0; 1692 ondisk->mirror_tid = leaf->ondisk->mirror_tid; 1693 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1694 ondisk->elms[0].base = hmp->root_btree_beg; 1695 ondisk->elms[0].base.btype = leaf->ondisk->type; 1696 ondisk->elms[0].internal.subtree_offset = leaf->node_offset; 1697 ondisk->elms[1].base = hmp->root_btree_end; 1698 /* ondisk->elms[1].base.btype = not used */ 1699 hammer_modify_node_done(parent); 1700 made_root = 1; 1701 parent_index = 0; /* insertion point in parent */ 1702 } else { 1703 made_root = 0; 1704 parent = cursor->parent; 1705 parent_index = cursor->parent_index; 1706 } 1707 1708 /* 1709 * Split leaf into new_leaf at the split point. Select a separator 1710 * value in-between the two leafs but with a bent towards the right 1711 * leaf since comparisons use an 'elm >= separator' inequality. 1712 * 1713 * L L L L L L L L 1714 * 1715 * x x P x x 1716 * s S S s 1717 * / \ 1718 * L L L L L L L L 1719 */ 1720 new_leaf = hammer_alloc_btree(cursor->trans, &error); 1721 if (new_leaf == NULL) { 1722 if (made_root) { 1723 hammer_unlock(&parent->lock); 1724 hammer_delete_node(cursor->trans, parent); 1725 hammer_rel_node(parent); 1726 } 1727 goto done; 1728 } 1729 hammer_lock_ex(&new_leaf->lock); 1730 1731 /* 1732 * Create the new node and copy the leaf elements from the split 1733 * point on to the new node. 1734 */ 1735 hammer_modify_node_all(cursor->trans, leaf); 1736 hammer_modify_node_noundo(cursor->trans, new_leaf); 1737 ondisk = leaf->ondisk; 1738 elm = &ondisk->elms[split]; 1739 bcopy(elm, &new_leaf->ondisk->elms[0], (ondisk->count - split) * esize); 1740 new_leaf->ondisk->count = ondisk->count - split; 1741 new_leaf->ondisk->parent = parent->node_offset; 1742 new_leaf->ondisk->type = HAMMER_BTREE_TYPE_LEAF; 1743 new_leaf->ondisk->mirror_tid = ondisk->mirror_tid; 1744 KKASSERT(ondisk->type == new_leaf->ondisk->type); 1745 hammer_modify_node_done(new_leaf); 1746 hammer_cursor_split_node(leaf, new_leaf, split); 1747 1748 /* 1749 * Cleanup the original node. Because this is a leaf node and 1750 * leaf nodes do not have a right-hand boundary, there 1751 * aren't any special edge cases to clean up. We just fixup the 1752 * count. 1753 */ 1754 ondisk->count = split; 1755 1756 /* 1757 * Insert the separator into the parent, fixup the parent's 1758 * reference to the original node, and reference the new node. 1759 * The separator is P. 1760 * 1761 * Remember that base.count does not include the right-hand boundary. 1762 * We are copying parent_index+1 to parent_index+2, not +0 to +1. 1763 */ 1764 hammer_modify_node_all(cursor->trans, parent); 1765 ondisk = parent->ondisk; 1766 KKASSERT(split != 0); 1767 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS); 1768 parent_elm = &ondisk->elms[parent_index+1]; 1769 bcopy(parent_elm, parent_elm + 1, 1770 (ondisk->count - parent_index) * esize); 1771 1772 hammer_make_separator(&elm[-1].base, &elm[0].base, &parent_elm->base); 1773 parent_elm->internal.base.btype = new_leaf->ondisk->type; 1774 parent_elm->internal.subtree_offset = new_leaf->node_offset; 1775 parent_elm->internal.mirror_tid = new_leaf->ondisk->mirror_tid; 1776 mid_boundary = &parent_elm->base; 1777 ++ondisk->count; 1778 hammer_modify_node_done(parent); 1779 hammer_cursor_inserted_element(parent, parent_index + 1); 1780 1781 /* 1782 * The filesystem's root B-Tree pointer may have to be updated. 1783 */ 1784 if (made_root) { 1785 hammer_volume_t volume; 1786 1787 volume = hammer_get_root_volume(hmp, &error); 1788 KKASSERT(error == 0); 1789 1790 hammer_modify_volume_field(cursor->trans, volume, 1791 vol0_btree_root); 1792 volume->ondisk->vol0_btree_root = parent->node_offset; 1793 hammer_modify_volume_done(volume); 1794 leaf->ondisk->parent = parent->node_offset; 1795 if (cursor->parent) { 1796 hammer_unlock(&cursor->parent->lock); 1797 hammer_rel_node(cursor->parent); 1798 } 1799 cursor->parent = parent; /* lock'd and ref'd */ 1800 hammer_rel_volume(volume, 0); 1801 } 1802 hammer_modify_node_done(leaf); 1803 1804 /* 1805 * Ok, now adjust the cursor depending on which element the original 1806 * index was pointing at. If we are >= the split point the push node 1807 * is now in the new node. 1808 * 1809 * NOTE: If we are at the split point itself we need to select the 1810 * old or new node based on where key_beg's insertion point will be. 1811 * If we pick the wrong side the inserted element will wind up in 1812 * the wrong leaf node and outside that node's bounds. 1813 */ 1814 if (cursor->index > split || 1815 (cursor->index == split && 1816 hammer_btree_cmp(&cursor->key_beg, mid_boundary) >= 0)) { 1817 cursor->parent_index = parent_index + 1; 1818 cursor->index -= split; 1819 hammer_unlock(&cursor->node->lock); 1820 hammer_rel_node(cursor->node); 1821 cursor->node = new_leaf; 1822 } else { 1823 cursor->parent_index = parent_index; 1824 hammer_unlock(&new_leaf->lock); 1825 hammer_rel_node(new_leaf); 1826 } 1827 1828 /* 1829 * Fixup left and right bounds 1830 */ 1831 parent_elm = &parent->ondisk->elms[cursor->parent_index]; 1832 cursor->left_bound = &parent_elm[0].internal.base; 1833 cursor->right_bound = &parent_elm[1].internal.base; 1834 1835 /* 1836 * Assert that the bounds are correct. 1837 */ 1838 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1839 &cursor->node->ondisk->elms[0].leaf.base) <= 0); 1840 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1841 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0); 1842 KKASSERT(hammer_btree_cmp(cursor->left_bound, &cursor->key_beg) <= 0); 1843 KKASSERT(hammer_btree_cmp(cursor->right_bound, &cursor->key_beg) > 0); 1844 1845 done: 1846 hammer_cursor_downgrade(cursor); 1847 return (error); 1848 } 1849 1850 #if 0 1851 1852 /* 1853 * Recursively correct the right-hand boundary's create_tid to (tid) as 1854 * long as the rest of the key matches. We have to recurse upward in 1855 * the tree as well as down the left side of each parent's right node. 1856 * 1857 * Return EDEADLK if we were only partially successful, forcing the caller 1858 * to try again. The original cursor is not modified. This routine can 1859 * also fail with EDEADLK if it is forced to throw away a portion of its 1860 * record history. 1861 * 1862 * The caller must pass a downgraded cursor to us (otherwise we can't dup it). 1863 */ 1864 struct hammer_rhb { 1865 TAILQ_ENTRY(hammer_rhb) entry; 1866 hammer_node_t node; 1867 int index; 1868 }; 1869 1870 TAILQ_HEAD(hammer_rhb_list, hammer_rhb); 1871 1872 int 1873 hammer_btree_correct_rhb(hammer_cursor_t cursor, hammer_tid_t tid) 1874 { 1875 struct hammer_mount *hmp; 1876 struct hammer_rhb_list rhb_list; 1877 hammer_base_elm_t elm; 1878 hammer_node_t orig_node; 1879 struct hammer_rhb *rhb; 1880 int orig_index; 1881 int error; 1882 1883 TAILQ_INIT(&rhb_list); 1884 hmp = cursor->trans->hmp; 1885 1886 /* 1887 * Save our position so we can restore it on return. This also 1888 * gives us a stable 'elm'. 1889 */ 1890 orig_node = cursor->node; 1891 hammer_ref_node(orig_node); 1892 hammer_lock_sh(&orig_node->lock); 1893 orig_index = cursor->index; 1894 elm = &orig_node->ondisk->elms[orig_index].base; 1895 1896 /* 1897 * Now build a list of parents going up, allocating a rhb 1898 * structure for each one. 1899 */ 1900 while (cursor->parent) { 1901 /* 1902 * Stop if we no longer have any right-bounds to fix up 1903 */ 1904 if (elm->obj_id != cursor->right_bound->obj_id || 1905 elm->rec_type != cursor->right_bound->rec_type || 1906 elm->key != cursor->right_bound->key) { 1907 break; 1908 } 1909 1910 /* 1911 * Stop if the right-hand bound's create_tid does not 1912 * need to be corrected. 1913 */ 1914 if (cursor->right_bound->create_tid >= tid) 1915 break; 1916 1917 rhb = kmalloc(sizeof(*rhb), hmp->m_misc, M_WAITOK|M_ZERO); 1918 rhb->node = cursor->parent; 1919 rhb->index = cursor->parent_index; 1920 hammer_ref_node(rhb->node); 1921 hammer_lock_sh(&rhb->node->lock); 1922 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry); 1923 1924 hammer_cursor_up(cursor); 1925 } 1926 1927 /* 1928 * now safely adjust the right hand bound for each rhb. This may 1929 * also require taking the right side of the tree and iterating down 1930 * ITS left side. 1931 */ 1932 error = 0; 1933 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 1934 error = hammer_cursor_seek(cursor, rhb->node, rhb->index); 1935 if (error) 1936 break; 1937 TAILQ_REMOVE(&rhb_list, rhb, entry); 1938 hammer_unlock(&rhb->node->lock); 1939 hammer_rel_node(rhb->node); 1940 kfree(rhb, hmp->m_misc); 1941 1942 switch (cursor->node->ondisk->type) { 1943 case HAMMER_BTREE_TYPE_INTERNAL: 1944 /* 1945 * Right-boundary for parent at internal node 1946 * is one element to the right of the element whos 1947 * right boundary needs adjusting. We must then 1948 * traverse down the left side correcting any left 1949 * bounds (which may now be too far to the left). 1950 */ 1951 ++cursor->index; 1952 error = hammer_btree_correct_lhb(cursor, tid); 1953 break; 1954 default: 1955 panic("hammer_btree_correct_rhb(): Bad node type"); 1956 error = EINVAL; 1957 break; 1958 } 1959 } 1960 1961 /* 1962 * Cleanup 1963 */ 1964 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 1965 TAILQ_REMOVE(&rhb_list, rhb, entry); 1966 hammer_unlock(&rhb->node->lock); 1967 hammer_rel_node(rhb->node); 1968 kfree(rhb, hmp->m_misc); 1969 } 1970 error = hammer_cursor_seek(cursor, orig_node, orig_index); 1971 hammer_unlock(&orig_node->lock); 1972 hammer_rel_node(orig_node); 1973 return (error); 1974 } 1975 1976 /* 1977 * Similar to rhb (in fact, rhb calls lhb), but corrects the left hand 1978 * bound going downward starting at the current cursor position. 1979 * 1980 * This function does not restore the cursor after use. 1981 */ 1982 int 1983 hammer_btree_correct_lhb(hammer_cursor_t cursor, hammer_tid_t tid) 1984 { 1985 struct hammer_rhb_list rhb_list; 1986 hammer_base_elm_t elm; 1987 hammer_base_elm_t cmp; 1988 struct hammer_rhb *rhb; 1989 struct hammer_mount *hmp; 1990 int error; 1991 1992 TAILQ_INIT(&rhb_list); 1993 hmp = cursor->trans->hmp; 1994 1995 cmp = &cursor->node->ondisk->elms[cursor->index].base; 1996 1997 /* 1998 * Record the node and traverse down the left-hand side for all 1999 * matching records needing a boundary correction. 2000 */ 2001 error = 0; 2002 for (;;) { 2003 rhb = kmalloc(sizeof(*rhb), hmp->m_misc, M_WAITOK|M_ZERO); 2004 rhb->node = cursor->node; 2005 rhb->index = cursor->index; 2006 hammer_ref_node(rhb->node); 2007 hammer_lock_sh(&rhb->node->lock); 2008 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry); 2009 2010 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2011 /* 2012 * Nothing to traverse down if we are at the right 2013 * boundary of an internal node. 2014 */ 2015 if (cursor->index == cursor->node->ondisk->count) 2016 break; 2017 } else { 2018 elm = &cursor->node->ondisk->elms[cursor->index].base; 2019 if (elm->btype == HAMMER_BTREE_TYPE_RECORD) 2020 break; 2021 panic("Illegal leaf record type %02x", elm->btype); 2022 } 2023 error = hammer_cursor_down(cursor); 2024 if (error) 2025 break; 2026 2027 elm = &cursor->node->ondisk->elms[cursor->index].base; 2028 if (elm->obj_id != cmp->obj_id || 2029 elm->rec_type != cmp->rec_type || 2030 elm->key != cmp->key) { 2031 break; 2032 } 2033 if (elm->create_tid >= tid) 2034 break; 2035 2036 } 2037 2038 /* 2039 * Now we can safely adjust the left-hand boundary from the bottom-up. 2040 * The last element we remove from the list is the caller's right hand 2041 * boundary, which must also be adjusted. 2042 */ 2043 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2044 error = hammer_cursor_seek(cursor, rhb->node, rhb->index); 2045 if (error) 2046 break; 2047 TAILQ_REMOVE(&rhb_list, rhb, entry); 2048 hammer_unlock(&rhb->node->lock); 2049 hammer_rel_node(rhb->node); 2050 kfree(rhb, hmp->m_misc); 2051 2052 elm = &cursor->node->ondisk->elms[cursor->index].base; 2053 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2054 hammer_modify_node(cursor->trans, cursor->node, 2055 &elm->create_tid, 2056 sizeof(elm->create_tid)); 2057 elm->create_tid = tid; 2058 hammer_modify_node_done(cursor->node); 2059 } else { 2060 panic("hammer_btree_correct_lhb(): Bad element type"); 2061 } 2062 } 2063 2064 /* 2065 * Cleanup 2066 */ 2067 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2068 TAILQ_REMOVE(&rhb_list, rhb, entry); 2069 hammer_unlock(&rhb->node->lock); 2070 hammer_rel_node(rhb->node); 2071 kfree(rhb, hmp->m_misc); 2072 } 2073 return (error); 2074 } 2075 2076 #endif 2077 2078 /* 2079 * Attempt to remove the locked, empty or want-to-be-empty B-Tree node at 2080 * (cursor->node). Returns 0 on success, EDEADLK if we could not complete 2081 * the operation due to a deadlock, or some other error. 2082 * 2083 * This routine is initially called with an empty leaf and may be 2084 * recursively called with single-element internal nodes. 2085 * 2086 * It should also be noted that when removing empty leaves we must be sure 2087 * to test and update mirror_tid because another thread may have deadlocked 2088 * against us (or someone) trying to propagate it up and cannot retry once 2089 * the node has been deleted. 2090 * 2091 * On return the cursor may end up pointing to an internal node, suitable 2092 * for further iteration but not for an immediate insertion or deletion. 2093 */ 2094 static int 2095 btree_remove(hammer_cursor_t cursor) 2096 { 2097 hammer_node_ondisk_t ondisk; 2098 hammer_btree_elm_t elm; 2099 hammer_node_t node; 2100 hammer_node_t parent; 2101 const int esize = sizeof(*elm); 2102 int error; 2103 2104 node = cursor->node; 2105 2106 /* 2107 * When deleting the root of the filesystem convert it to 2108 * an empty leaf node. Internal nodes cannot be empty. 2109 */ 2110 ondisk = node->ondisk; 2111 if (ondisk->parent == 0) { 2112 KKASSERT(cursor->parent == NULL); 2113 hammer_modify_node_all(cursor->trans, node); 2114 KKASSERT(ondisk == node->ondisk); 2115 ondisk->type = HAMMER_BTREE_TYPE_LEAF; 2116 ondisk->count = 0; 2117 hammer_modify_node_done(node); 2118 cursor->index = 0; 2119 return(0); 2120 } 2121 2122 parent = cursor->parent; 2123 hammer_cursor_removed_node(node, parent, cursor->parent_index); 2124 2125 /* 2126 * Attempt to remove the parent's reference to the child. If the 2127 * parent would become empty we have to recurse. If we fail we 2128 * leave the parent pointing to an empty leaf node. 2129 * 2130 * We have to recurse successfully before we can delete the internal 2131 * node as it is illegal to have empty internal nodes. Even though 2132 * the operation may be aborted we must still fixup any unlocked 2133 * cursors as if we had deleted the element prior to recursing 2134 * (by calling hammer_cursor_deleted_element()) so those cursors 2135 * are properly forced up the chain by the recursion. 2136 */ 2137 if (parent->ondisk->count == 1) { 2138 /* 2139 * This special cursor_up_locked() call leaves the original 2140 * node exclusively locked and referenced, leaves the 2141 * original parent locked (as the new node), and locks the 2142 * new parent. It can return EDEADLK. 2143 */ 2144 error = hammer_cursor_up_locked(cursor); 2145 if (error == 0) { 2146 hammer_cursor_deleted_element(cursor->node, 0); 2147 error = btree_remove(cursor); 2148 if (error == 0) { 2149 hammer_modify_node_all(cursor->trans, node); 2150 ondisk = node->ondisk; 2151 ondisk->type = HAMMER_BTREE_TYPE_DELETED; 2152 ondisk->count = 0; 2153 hammer_modify_node_done(node); 2154 hammer_flush_node(node); 2155 hammer_delete_node(cursor->trans, node); 2156 } else { 2157 kprintf("Warning: BTREE_REMOVE: Defering " 2158 "parent removal1 @ %016llx, skipping\n", 2159 node->node_offset); 2160 } 2161 hammer_unlock(&node->lock); 2162 hammer_rel_node(node); 2163 } else { 2164 kprintf("Warning: BTREE_REMOVE: Defering parent " 2165 "removal2 @ %016llx, skipping\n", 2166 node->node_offset); 2167 } 2168 } else { 2169 KKASSERT(parent->ondisk->count > 1); 2170 2171 hammer_modify_node_all(cursor->trans, parent); 2172 ondisk = parent->ondisk; 2173 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_INTERNAL); 2174 2175 elm = &ondisk->elms[cursor->parent_index]; 2176 KKASSERT(elm->internal.subtree_offset == node->node_offset); 2177 KKASSERT(ondisk->count > 0); 2178 2179 /* 2180 * We must retain the highest mirror_tid. The deleted 2181 * range is now encompassed by the element to the left. 2182 * If we are already at the left edge the new left edge 2183 * inherits mirror_tid. 2184 * 2185 * Note that bounds of the parent to our parent may create 2186 * a gap to the left of our left-most node or to the right 2187 * of our right-most node. The gap is silently included 2188 * in the mirror_tid's area of effect from the point of view 2189 * of the scan. 2190 */ 2191 if (cursor->parent_index) { 2192 if (elm[-1].internal.mirror_tid < 2193 elm[0].internal.mirror_tid) { 2194 elm[-1].internal.mirror_tid = 2195 elm[0].internal.mirror_tid; 2196 } 2197 } else { 2198 if (elm[1].internal.mirror_tid < 2199 elm[0].internal.mirror_tid) { 2200 elm[1].internal.mirror_tid = 2201 elm[0].internal.mirror_tid; 2202 } 2203 } 2204 2205 /* 2206 * Delete the subtree reference in the parent 2207 */ 2208 bcopy(&elm[1], &elm[0], 2209 (ondisk->count - cursor->parent_index) * esize); 2210 --ondisk->count; 2211 hammer_modify_node_done(parent); 2212 hammer_cursor_deleted_element(parent, cursor->parent_index); 2213 hammer_flush_node(node); 2214 hammer_delete_node(cursor->trans, node); 2215 2216 /* 2217 * cursor->node is invalid, cursor up to make the cursor 2218 * valid again. 2219 */ 2220 error = hammer_cursor_up(cursor); 2221 } 2222 return (error); 2223 } 2224 2225 /* 2226 * Propagate cursor->trans->tid up the B-Tree starting at the current 2227 * cursor position using pseudofs info gleaned from the passed inode. 2228 * 2229 * The passed inode has no relationship to the cursor position other 2230 * then being in the same pseudofs as the insertion or deletion we 2231 * are propagating the mirror_tid for. 2232 */ 2233 void 2234 hammer_btree_do_propagation(hammer_cursor_t cursor, 2235 hammer_pseudofs_inmem_t pfsm, 2236 hammer_btree_leaf_elm_t leaf) 2237 { 2238 hammer_cursor_t ncursor; 2239 hammer_tid_t mirror_tid; 2240 int error; 2241 2242 /* 2243 * We do not propagate a mirror_tid if the filesystem was mounted 2244 * in no-mirror mode. 2245 */ 2246 if (cursor->trans->hmp->master_id < 0) 2247 return; 2248 2249 /* 2250 * This is a bit of a hack because we cannot deadlock or return 2251 * EDEADLK here. The related operation has already completed and 2252 * we must propagate the mirror_tid now regardless. 2253 * 2254 * Generate a new cursor which inherits the original's locks and 2255 * unlock the original. Use the new cursor to propagate the 2256 * mirror_tid. Then clean up the new cursor and reacquire locks 2257 * on the original. 2258 * 2259 * hammer_dup_cursor() cannot dup locks. The dup inherits the 2260 * original's locks and the original is tracked and must be 2261 * re-locked. 2262 */ 2263 mirror_tid = cursor->node->ondisk->mirror_tid; 2264 KKASSERT(mirror_tid != 0); 2265 ncursor = hammer_push_cursor(cursor); 2266 error = hammer_btree_mirror_propagate(ncursor, mirror_tid); 2267 KKASSERT(error == 0); 2268 hammer_pop_cursor(cursor, ncursor); 2269 } 2270 2271 2272 /* 2273 * Propagate a mirror TID update upwards through the B-Tree to the root. 2274 * 2275 * A locked internal node must be passed in. The node will remain locked 2276 * on return. 2277 * 2278 * This function syncs mirror_tid at the specified internal node's element, 2279 * adjusts the node's aggregation mirror_tid, and then recurses upwards. 2280 */ 2281 static int 2282 hammer_btree_mirror_propagate(hammer_cursor_t cursor, hammer_tid_t mirror_tid) 2283 { 2284 hammer_btree_internal_elm_t elm; 2285 hammer_node_t node; 2286 int error; 2287 2288 for (;;) { 2289 error = hammer_cursor_up(cursor); 2290 if (error == 0) 2291 error = hammer_cursor_upgrade(cursor); 2292 while (error == EDEADLK) { 2293 hammer_recover_cursor(cursor); 2294 error = hammer_cursor_upgrade(cursor); 2295 } 2296 if (error) 2297 break; 2298 node = cursor->node; 2299 KKASSERT (node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL); 2300 2301 /* 2302 * Adjust the node's element 2303 */ 2304 elm = &node->ondisk->elms[cursor->index].internal; 2305 if (elm->mirror_tid >= mirror_tid) 2306 break; 2307 hammer_modify_node(cursor->trans, node, &elm->mirror_tid, 2308 sizeof(elm->mirror_tid)); 2309 elm->mirror_tid = mirror_tid; 2310 hammer_modify_node_done(node); 2311 if (hammer_debug_general & 0x0002) { 2312 kprintf("mirror_propagate: propagate " 2313 "%016llx @%016llx:%d\n", 2314 mirror_tid, node->node_offset, cursor->index); 2315 } 2316 2317 2318 /* 2319 * Adjust the node's mirror_tid aggregator 2320 */ 2321 if (node->ondisk->mirror_tid >= mirror_tid) 2322 return(0); 2323 hammer_modify_node_field(cursor->trans, node, mirror_tid); 2324 node->ondisk->mirror_tid = mirror_tid; 2325 hammer_modify_node_done(node); 2326 if (hammer_debug_general & 0x0002) { 2327 kprintf("mirror_propagate: propagate " 2328 "%016llx @%016llx\n", 2329 mirror_tid, node->node_offset); 2330 } 2331 } 2332 if (error == ENOENT) 2333 error = 0; 2334 return(error); 2335 } 2336 2337 hammer_node_t 2338 hammer_btree_get_parent(hammer_transaction_t trans, hammer_node_t node, 2339 int *parent_indexp, int *errorp, int try_exclusive) 2340 { 2341 hammer_node_t parent; 2342 hammer_btree_elm_t elm; 2343 int i; 2344 2345 /* 2346 * Get the node 2347 */ 2348 parent = hammer_get_node(trans, node->ondisk->parent, 0, errorp); 2349 if (*errorp) { 2350 KKASSERT(parent == NULL); 2351 return(NULL); 2352 } 2353 KKASSERT ((parent->flags & HAMMER_NODE_DELETED) == 0); 2354 2355 /* 2356 * Lock the node 2357 */ 2358 if (try_exclusive) { 2359 if (hammer_lock_ex_try(&parent->lock)) { 2360 hammer_rel_node(parent); 2361 *errorp = EDEADLK; 2362 return(NULL); 2363 } 2364 } else { 2365 hammer_lock_sh(&parent->lock); 2366 } 2367 2368 /* 2369 * Figure out which element in the parent is pointing to the 2370 * child. 2371 */ 2372 if (node->ondisk->count) { 2373 i = hammer_btree_search_node(&node->ondisk->elms[0].base, 2374 parent->ondisk); 2375 } else { 2376 i = 0; 2377 } 2378 while (i < parent->ondisk->count) { 2379 elm = &parent->ondisk->elms[i]; 2380 if (elm->internal.subtree_offset == node->node_offset) 2381 break; 2382 ++i; 2383 } 2384 if (i == parent->ondisk->count) { 2385 hammer_unlock(&parent->lock); 2386 panic("Bad B-Tree link: parent %p node %p\n", parent, node); 2387 } 2388 *parent_indexp = i; 2389 KKASSERT(*errorp == 0); 2390 return(parent); 2391 } 2392 2393 /* 2394 * The element (elm) has been moved to a new internal node (node). 2395 * 2396 * If the element represents a pointer to an internal node that node's 2397 * parent must be adjusted to the element's new location. 2398 * 2399 * XXX deadlock potential here with our exclusive locks 2400 */ 2401 int 2402 btree_set_parent(hammer_transaction_t trans, hammer_node_t node, 2403 hammer_btree_elm_t elm) 2404 { 2405 hammer_node_t child; 2406 int error; 2407 2408 error = 0; 2409 2410 switch(elm->base.btype) { 2411 case HAMMER_BTREE_TYPE_INTERNAL: 2412 case HAMMER_BTREE_TYPE_LEAF: 2413 child = hammer_get_node(trans, elm->internal.subtree_offset, 2414 0, &error); 2415 if (error == 0) { 2416 hammer_modify_node_field(trans, child, parent); 2417 child->ondisk->parent = node->node_offset; 2418 hammer_modify_node_done(child); 2419 hammer_rel_node(child); 2420 } 2421 break; 2422 default: 2423 break; 2424 } 2425 return(error); 2426 } 2427 2428 /* 2429 * Initialize the root of a recursive B-Tree node lock list structure. 2430 */ 2431 void 2432 hammer_node_lock_init(hammer_node_lock_t parent, hammer_node_t node) 2433 { 2434 TAILQ_INIT(&parent->list); 2435 parent->parent = NULL; 2436 parent->node = node; 2437 parent->index = -1; 2438 parent->count = node->ondisk->count; 2439 parent->copy = NULL; 2440 parent->flags = 0; 2441 } 2442 2443 /* 2444 * Exclusively lock all the children of node. This is used by the split 2445 * code to prevent anyone from accessing the children of a cursor node 2446 * while we fix-up its parent offset. 2447 * 2448 * If we don't lock the children we can really mess up cursors which block 2449 * trying to cursor-up into our node. 2450 * 2451 * On failure EDEADLK (or some other error) is returned. If a deadlock 2452 * error is returned the cursor is adjusted to block on termination. 2453 * 2454 * The caller is responsible for managing parent->node, the root's node 2455 * is usually aliased from a cursor. 2456 */ 2457 int 2458 hammer_btree_lock_children(hammer_cursor_t cursor, int depth, 2459 hammer_node_lock_t parent) 2460 { 2461 hammer_node_t node; 2462 hammer_node_lock_t item; 2463 hammer_node_ondisk_t ondisk; 2464 hammer_btree_elm_t elm; 2465 hammer_node_t child; 2466 struct hammer_mount *hmp; 2467 int error; 2468 int i; 2469 2470 node = parent->node; 2471 ondisk = node->ondisk; 2472 error = 0; 2473 hmp = cursor->trans->hmp; 2474 2475 /* 2476 * We really do not want to block on I/O with exclusive locks held, 2477 * pre-get the children before trying to lock the mess. This is 2478 * only done one-level deep for now. 2479 */ 2480 for (i = 0; i < ondisk->count; ++i) { 2481 ++hammer_stats_btree_elements; 2482 elm = &ondisk->elms[i]; 2483 if (elm->base.btype != HAMMER_BTREE_TYPE_LEAF && 2484 elm->base.btype != HAMMER_BTREE_TYPE_INTERNAL) { 2485 continue; 2486 } 2487 child = hammer_get_node(cursor->trans, 2488 elm->internal.subtree_offset, 2489 0, &error); 2490 if (child) 2491 hammer_rel_node(child); 2492 } 2493 2494 /* 2495 * Do it for real 2496 */ 2497 for (i = 0; error == 0 && i < ondisk->count; ++i) { 2498 ++hammer_stats_btree_elements; 2499 elm = &ondisk->elms[i]; 2500 2501 switch(elm->base.btype) { 2502 case HAMMER_BTREE_TYPE_INTERNAL: 2503 case HAMMER_BTREE_TYPE_LEAF: 2504 KKASSERT(elm->internal.subtree_offset != 0); 2505 child = hammer_get_node(cursor->trans, 2506 elm->internal.subtree_offset, 2507 0, &error); 2508 break; 2509 default: 2510 child = NULL; 2511 break; 2512 } 2513 if (child) { 2514 if (hammer_lock_ex_try(&child->lock) != 0) { 2515 if (cursor->deadlk_node == NULL) { 2516 cursor->deadlk_node = child; 2517 hammer_ref_node(cursor->deadlk_node); 2518 } 2519 error = EDEADLK; 2520 hammer_rel_node(child); 2521 } else { 2522 item = kmalloc(sizeof(*item), hmp->m_misc, 2523 M_WAITOK|M_ZERO); 2524 TAILQ_INSERT_TAIL(&parent->list, item, entry); 2525 TAILQ_INIT(&item->list); 2526 item->parent = parent; 2527 item->node = child; 2528 item->index = i; 2529 item->count = child->ondisk->count; 2530 2531 /* 2532 * Recurse (used by the rebalancing code) 2533 */ 2534 if (depth > 1 && elm->base.btype == HAMMER_BTREE_TYPE_INTERNAL) { 2535 error = hammer_btree_lock_children( 2536 cursor, 2537 depth - 1, 2538 item); 2539 } 2540 } 2541 } 2542 } 2543 if (error) 2544 hammer_btree_unlock_children(cursor, parent); 2545 return(error); 2546 } 2547 2548 /* 2549 * Create an in-memory copy of all B-Tree nodes listed, recursively, 2550 * including the parent. 2551 */ 2552 void 2553 hammer_btree_lock_copy(hammer_cursor_t cursor, hammer_node_lock_t parent) 2554 { 2555 hammer_mount_t hmp = cursor->trans->hmp; 2556 hammer_node_lock_t item; 2557 2558 if (parent->copy == NULL) { 2559 parent->copy = kmalloc(sizeof(*parent->copy), hmp->m_misc, 2560 M_WAITOK); 2561 *parent->copy = *parent->node->ondisk; 2562 } 2563 TAILQ_FOREACH(item, &parent->list, entry) { 2564 hammer_btree_lock_copy(cursor, item); 2565 } 2566 } 2567 2568 /* 2569 * Recursively sync modified copies to the media. 2570 */ 2571 int 2572 hammer_btree_sync_copy(hammer_cursor_t cursor, hammer_node_lock_t parent) 2573 { 2574 hammer_node_lock_t item; 2575 int count = 0; 2576 2577 if (parent->flags & HAMMER_NODE_LOCK_UPDATED) { 2578 ++count; 2579 hammer_modify_node_all(cursor->trans, parent->node); 2580 *parent->node->ondisk = *parent->copy; 2581 hammer_modify_node_done(parent->node); 2582 if (parent->copy->type == HAMMER_BTREE_TYPE_DELETED) { 2583 hammer_flush_node(parent->node); 2584 hammer_delete_node(cursor->trans, parent->node); 2585 } 2586 } 2587 TAILQ_FOREACH(item, &parent->list, entry) { 2588 count += hammer_btree_sync_copy(cursor, item); 2589 } 2590 return(count); 2591 } 2592 2593 /* 2594 * Release previously obtained node locks. The caller is responsible for 2595 * cleaning up parent->node itself (its usually just aliased from a cursor), 2596 * but this function will take care of the copies. 2597 */ 2598 void 2599 hammer_btree_unlock_children(hammer_cursor_t cursor, hammer_node_lock_t parent) 2600 { 2601 hammer_node_lock_t item; 2602 2603 if (parent->copy) { 2604 kfree(parent->copy, cursor->trans->hmp->m_misc); 2605 parent->copy = NULL; /* safety */ 2606 } 2607 while ((item = TAILQ_FIRST(&parent->list)) != NULL) { 2608 TAILQ_REMOVE(&parent->list, item, entry); 2609 hammer_btree_unlock_children(cursor, item); 2610 hammer_unlock(&item->node->lock); 2611 hammer_rel_node(item->node); 2612 kfree(item, cursor->trans->hmp->m_misc); 2613 } 2614 } 2615 2616 /************************************************************************ 2617 * MISCELLANIOUS SUPPORT * 2618 ************************************************************************/ 2619 2620 /* 2621 * Compare two B-Tree elements, return -N, 0, or +N (e.g. similar to strcmp). 2622 * 2623 * Note that for this particular function a return value of -1, 0, or +1 2624 * can denote a match if create_tid is otherwise discounted. A create_tid 2625 * of zero is considered to be 'infinity' in comparisons. 2626 * 2627 * See also hammer_rec_rb_compare() and hammer_rec_cmp() in hammer_object.c. 2628 */ 2629 int 2630 hammer_btree_cmp(hammer_base_elm_t key1, hammer_base_elm_t key2) 2631 { 2632 if (key1->localization < key2->localization) 2633 return(-5); 2634 if (key1->localization > key2->localization) 2635 return(5); 2636 2637 if (key1->obj_id < key2->obj_id) 2638 return(-4); 2639 if (key1->obj_id > key2->obj_id) 2640 return(4); 2641 2642 if (key1->rec_type < key2->rec_type) 2643 return(-3); 2644 if (key1->rec_type > key2->rec_type) 2645 return(3); 2646 2647 if (key1->key < key2->key) 2648 return(-2); 2649 if (key1->key > key2->key) 2650 return(2); 2651 2652 /* 2653 * A create_tid of zero indicates a record which is undeletable 2654 * and must be considered to have a value of positive infinity. 2655 */ 2656 if (key1->create_tid == 0) { 2657 if (key2->create_tid == 0) 2658 return(0); 2659 return(1); 2660 } 2661 if (key2->create_tid == 0) 2662 return(-1); 2663 if (key1->create_tid < key2->create_tid) 2664 return(-1); 2665 if (key1->create_tid > key2->create_tid) 2666 return(1); 2667 return(0); 2668 } 2669 2670 /* 2671 * Test a timestamp against an element to determine whether the 2672 * element is visible. A timestamp of 0 means 'infinity'. 2673 */ 2674 int 2675 hammer_btree_chkts(hammer_tid_t asof, hammer_base_elm_t base) 2676 { 2677 if (asof == 0) { 2678 if (base->delete_tid) 2679 return(1); 2680 return(0); 2681 } 2682 if (asof < base->create_tid) 2683 return(-1); 2684 if (base->delete_tid && asof >= base->delete_tid) 2685 return(1); 2686 return(0); 2687 } 2688 2689 /* 2690 * Create a separator half way inbetween key1 and key2. For fields just 2691 * one unit apart, the separator will match key2. key1 is on the left-hand 2692 * side and key2 is on the right-hand side. 2693 * 2694 * key2 must be >= the separator. It is ok for the separator to match key2. 2695 * 2696 * NOTE: Even if key1 does not match key2, the separator may wind up matching 2697 * key2. 2698 * 2699 * NOTE: It might be beneficial to just scrap this whole mess and just 2700 * set the separator to key2. 2701 */ 2702 #define MAKE_SEPARATOR(key1, key2, dest, field) \ 2703 dest->field = key1->field + ((key2->field - key1->field + 1) >> 1); 2704 2705 static void 2706 hammer_make_separator(hammer_base_elm_t key1, hammer_base_elm_t key2, 2707 hammer_base_elm_t dest) 2708 { 2709 bzero(dest, sizeof(*dest)); 2710 2711 dest->rec_type = key2->rec_type; 2712 dest->key = key2->key; 2713 dest->obj_id = key2->obj_id; 2714 dest->create_tid = key2->create_tid; 2715 2716 MAKE_SEPARATOR(key1, key2, dest, localization); 2717 if (key1->localization == key2->localization) { 2718 MAKE_SEPARATOR(key1, key2, dest, obj_id); 2719 if (key1->obj_id == key2->obj_id) { 2720 MAKE_SEPARATOR(key1, key2, dest, rec_type); 2721 if (key1->rec_type == key2->rec_type) { 2722 MAKE_SEPARATOR(key1, key2, dest, key); 2723 /* 2724 * Don't bother creating a separator for 2725 * create_tid, which also conveniently avoids 2726 * having to handle the create_tid == 0 2727 * (infinity) case. Just leave create_tid 2728 * set to key2. 2729 * 2730 * Worst case, dest matches key2 exactly, 2731 * which is acceptable. 2732 */ 2733 } 2734 } 2735 } 2736 } 2737 2738 #undef MAKE_SEPARATOR 2739 2740 /* 2741 * Return whether a generic internal or leaf node is full 2742 */ 2743 static int 2744 btree_node_is_full(hammer_node_ondisk_t node) 2745 { 2746 switch(node->type) { 2747 case HAMMER_BTREE_TYPE_INTERNAL: 2748 if (node->count == HAMMER_BTREE_INT_ELMS) 2749 return(1); 2750 break; 2751 case HAMMER_BTREE_TYPE_LEAF: 2752 if (node->count == HAMMER_BTREE_LEAF_ELMS) 2753 return(1); 2754 break; 2755 default: 2756 panic("illegal btree subtype"); 2757 } 2758 return(0); 2759 } 2760 2761 #if 0 2762 static int 2763 btree_max_elements(u_int8_t type) 2764 { 2765 if (type == HAMMER_BTREE_TYPE_LEAF) 2766 return(HAMMER_BTREE_LEAF_ELMS); 2767 if (type == HAMMER_BTREE_TYPE_INTERNAL) 2768 return(HAMMER_BTREE_INT_ELMS); 2769 panic("btree_max_elements: bad type %d\n", type); 2770 } 2771 #endif 2772 2773 void 2774 hammer_print_btree_node(hammer_node_ondisk_t ondisk) 2775 { 2776 hammer_btree_elm_t elm; 2777 int i; 2778 2779 kprintf("node %p count=%d parent=%016llx type=%c\n", 2780 ondisk, ondisk->count, ondisk->parent, ondisk->type); 2781 2782 /* 2783 * Dump both boundary elements if an internal node 2784 */ 2785 if (ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2786 for (i = 0; i <= ondisk->count; ++i) { 2787 elm = &ondisk->elms[i]; 2788 hammer_print_btree_elm(elm, ondisk->type, i); 2789 } 2790 } else { 2791 for (i = 0; i < ondisk->count; ++i) { 2792 elm = &ondisk->elms[i]; 2793 hammer_print_btree_elm(elm, ondisk->type, i); 2794 } 2795 } 2796 } 2797 2798 void 2799 hammer_print_btree_elm(hammer_btree_elm_t elm, u_int8_t type, int i) 2800 { 2801 kprintf(" %2d", i); 2802 kprintf("\tobj_id = %016llx\n", elm->base.obj_id); 2803 kprintf("\tkey = %016llx\n", elm->base.key); 2804 kprintf("\tcreate_tid = %016llx\n", elm->base.create_tid); 2805 kprintf("\tdelete_tid = %016llx\n", elm->base.delete_tid); 2806 kprintf("\trec_type = %04x\n", elm->base.rec_type); 2807 kprintf("\tobj_type = %02x\n", elm->base.obj_type); 2808 kprintf("\tbtype = %02x (%c)\n", 2809 elm->base.btype, 2810 (elm->base.btype ? elm->base.btype : '?')); 2811 kprintf("\tlocalization = %02x\n", elm->base.localization); 2812 2813 switch(type) { 2814 case HAMMER_BTREE_TYPE_INTERNAL: 2815 kprintf("\tsubtree_off = %016llx\n", 2816 elm->internal.subtree_offset); 2817 break; 2818 case HAMMER_BTREE_TYPE_RECORD: 2819 kprintf("\tdata_offset = %016llx\n", elm->leaf.data_offset); 2820 kprintf("\tdata_len = %08x\n", elm->leaf.data_len); 2821 kprintf("\tdata_crc = %08x\n", elm->leaf.data_crc); 2822 break; 2823 } 2824 } 2825