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 * Set ATEDISK so a low-level caller can call btree_first/btree_iterate 619 * in a loop without worrying about it. Higher-level merged searches will 620 * adjust the flag appropriately. 621 */ 622 int 623 hammer_btree_first(hammer_cursor_t cursor) 624 { 625 int error; 626 627 error = hammer_btree_lookup(cursor); 628 if (error == ENOENT) { 629 cursor->flags &= ~HAMMER_CURSOR_ATEDISK; 630 error = hammer_btree_iterate(cursor); 631 } 632 cursor->flags |= HAMMER_CURSOR_ATEDISK; 633 return(error); 634 } 635 636 /* 637 * Similarly but for an iteration in the reverse direction. 638 * 639 * Set ATEDISK when iterating backwards to skip the current entry, 640 * which after an ENOENT lookup will be pointing beyond our end point. 641 * 642 * Set ATEDISK so a low-level caller can call btree_last/btree_iterate_reverse 643 * in a loop without worrying about it. Higher-level merged searches will 644 * adjust the flag appropriately. 645 */ 646 int 647 hammer_btree_last(hammer_cursor_t cursor) 648 { 649 struct hammer_base_elm save; 650 int error; 651 652 save = cursor->key_beg; 653 cursor->key_beg = cursor->key_end; 654 error = hammer_btree_lookup(cursor); 655 cursor->key_beg = save; 656 if (error == ENOENT || 657 (cursor->flags & HAMMER_CURSOR_END_INCLUSIVE) == 0) { 658 cursor->flags |= HAMMER_CURSOR_ATEDISK; 659 error = hammer_btree_iterate_reverse(cursor); 660 } 661 cursor->flags |= HAMMER_CURSOR_ATEDISK; 662 return(error); 663 } 664 665 /* 666 * Extract the record and/or data associated with the cursor's current 667 * position. Any prior record or data stored in the cursor is replaced. 668 * The cursor must be positioned at a leaf node. 669 * 670 * NOTE: All extractions occur at the leaf of the B-Tree. 671 */ 672 int 673 hammer_btree_extract(hammer_cursor_t cursor, int flags) 674 { 675 hammer_node_ondisk_t node; 676 hammer_btree_elm_t elm; 677 hammer_off_t data_off; 678 hammer_mount_t hmp; 679 int32_t data_len; 680 int error; 681 682 /* 683 * The case where the data reference resolves to the same buffer 684 * as the record reference must be handled. 685 */ 686 node = cursor->node->ondisk; 687 elm = &node->elms[cursor->index]; 688 cursor->data = NULL; 689 hmp = cursor->node->hmp; 690 691 /* 692 * There is nothing to extract for an internal element. 693 */ 694 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) 695 return(EINVAL); 696 697 /* 698 * Only record types have data. 699 */ 700 KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF); 701 cursor->leaf = &elm->leaf; 702 703 if ((flags & HAMMER_CURSOR_GET_DATA) == 0) 704 return(0); 705 if (elm->leaf.base.btype != HAMMER_BTREE_TYPE_RECORD) 706 return(0); 707 data_off = elm->leaf.data_offset; 708 data_len = elm->leaf.data_len; 709 if (data_off == 0) 710 return(0); 711 712 /* 713 * Load the data 714 */ 715 KKASSERT(data_len >= 0 && data_len <= HAMMER_XBUFSIZE); 716 cursor->data = hammer_bread_ext(hmp, data_off, data_len, 717 &error, &cursor->data_buffer); 718 if (hammer_crc_test_leaf(cursor->data, &elm->leaf) == 0) { 719 kprintf("CRC DATA @ %016llx/%d FAILED\n", 720 elm->leaf.data_offset, elm->leaf.data_len); 721 if (hammer_debug_debug & 0x0001) 722 Debugger("CRC FAILED: DATA"); 723 if (cursor->trans->flags & HAMMER_TRANSF_CRCDOM) 724 error = EDOM; /* less critical (mirroring) */ 725 else 726 error = EIO; /* critical */ 727 } 728 return(error); 729 } 730 731 732 /* 733 * Insert a leaf element into the B-Tree at the current cursor position. 734 * The cursor is positioned such that the element at and beyond the cursor 735 * are shifted to make room for the new record. 736 * 737 * The caller must call hammer_btree_lookup() with the HAMMER_CURSOR_INSERT 738 * flag set and that call must return ENOENT before this function can be 739 * called. 740 * 741 * The caller may depend on the cursor's exclusive lock after return to 742 * interlock frontend visibility (see HAMMER_RECF_CONVERT_DELETE). 743 * 744 * ENOSPC is returned if there is no room to insert a new record. 745 */ 746 int 747 hammer_btree_insert(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm, 748 int *doprop) 749 { 750 hammer_node_ondisk_t node; 751 int i; 752 int error; 753 754 *doprop = 0; 755 if ((error = hammer_cursor_upgrade_node(cursor)) != 0) 756 return(error); 757 ++hammer_stats_btree_inserts; 758 759 /* 760 * Insert the element at the leaf node and update the count in the 761 * parent. It is possible for parent to be NULL, indicating that 762 * the filesystem's ROOT B-Tree node is a leaf itself, which is 763 * possible. The root inode can never be deleted so the leaf should 764 * never be empty. 765 * 766 * Remember that the right-hand boundary is not included in the 767 * count. 768 */ 769 hammer_modify_node_all(cursor->trans, cursor->node); 770 node = cursor->node->ondisk; 771 i = cursor->index; 772 KKASSERT(elm->base.btype != 0); 773 KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF); 774 KKASSERT(node->count < HAMMER_BTREE_LEAF_ELMS); 775 if (i != node->count) { 776 bcopy(&node->elms[i], &node->elms[i+1], 777 (node->count - i) * sizeof(*elm)); 778 } 779 node->elms[i].leaf = *elm; 780 ++node->count; 781 hammer_cursor_inserted_element(cursor->node, i); 782 783 /* 784 * Update the leaf node's aggregate mirror_tid for mirroring 785 * support. 786 */ 787 if (node->mirror_tid < elm->base.delete_tid) { 788 node->mirror_tid = elm->base.delete_tid; 789 *doprop = 1; 790 } 791 if (node->mirror_tid < elm->base.create_tid) { 792 node->mirror_tid = elm->base.create_tid; 793 *doprop = 1; 794 } 795 hammer_modify_node_done(cursor->node); 796 797 /* 798 * Debugging sanity checks. 799 */ 800 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->base) <= 0); 801 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->base) > 0); 802 if (i) { 803 KKASSERT(hammer_btree_cmp(&node->elms[i-1].leaf.base, &elm->base) < 0); 804 } 805 if (i != node->count - 1) 806 KKASSERT(hammer_btree_cmp(&node->elms[i+1].leaf.base, &elm->base) > 0); 807 808 return(0); 809 } 810 811 /* 812 * Delete a record from the B-Tree at the current cursor position. 813 * The cursor is positioned such that the current element is the one 814 * to be deleted. 815 * 816 * On return the cursor will be positioned after the deleted element and 817 * MAY point to an internal node. It will be suitable for the continuation 818 * of an iteration but not for an insertion or deletion. 819 * 820 * Deletions will attempt to partially rebalance the B-Tree in an upward 821 * direction, but will terminate rather then deadlock. Empty internal nodes 822 * are never allowed by a deletion which deadlocks may end up giving us an 823 * empty leaf. The pruner will clean up and rebalance the tree. 824 * 825 * This function can return EDEADLK, requiring the caller to retry the 826 * operation after clearing the deadlock. 827 */ 828 int 829 hammer_btree_delete(hammer_cursor_t cursor) 830 { 831 hammer_node_ondisk_t ondisk; 832 hammer_node_t node; 833 hammer_node_t parent; 834 int error; 835 int i; 836 837 KKASSERT (cursor->trans->sync_lock_refs > 0); 838 if ((error = hammer_cursor_upgrade(cursor)) != 0) 839 return(error); 840 ++hammer_stats_btree_deletes; 841 842 /* 843 * Delete the element from the leaf node. 844 * 845 * Remember that leaf nodes do not have boundaries. 846 */ 847 node = cursor->node; 848 ondisk = node->ondisk; 849 i = cursor->index; 850 851 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_LEAF); 852 KKASSERT(i >= 0 && i < ondisk->count); 853 hammer_modify_node_all(cursor->trans, node); 854 if (i + 1 != ondisk->count) { 855 bcopy(&ondisk->elms[i+1], &ondisk->elms[i], 856 (ondisk->count - i - 1) * sizeof(ondisk->elms[0])); 857 } 858 --ondisk->count; 859 hammer_modify_node_done(node); 860 hammer_cursor_deleted_element(node, i); 861 862 /* 863 * Validate local parent 864 */ 865 if (ondisk->parent) { 866 parent = cursor->parent; 867 868 KKASSERT(parent != NULL); 869 KKASSERT(parent->node_offset == ondisk->parent); 870 } 871 872 /* 873 * If the leaf becomes empty it must be detached from the parent, 874 * potentially recursing through to the filesystem root. 875 * 876 * This may reposition the cursor at one of the parent's of the 877 * current node. 878 * 879 * Ignore deadlock errors, that simply means that btree_remove 880 * was unable to recurse and had to leave us with an empty leaf. 881 */ 882 KKASSERT(cursor->index <= ondisk->count); 883 if (ondisk->count == 0) { 884 error = btree_remove(cursor); 885 if (error == EDEADLK) 886 error = 0; 887 } else { 888 error = 0; 889 } 890 KKASSERT(cursor->parent == NULL || 891 cursor->parent_index < cursor->parent->ondisk->count); 892 return(error); 893 } 894 895 /* 896 * PRIMAY B-TREE SEARCH SUPPORT PROCEDURE 897 * 898 * Search the filesystem B-Tree for cursor->key_beg, return the matching node. 899 * 900 * The search can begin ANYWHERE in the B-Tree. As a first step the search 901 * iterates up the tree as necessary to properly position itself prior to 902 * actually doing the sarch. 903 * 904 * INSERTIONS: The search will split full nodes and leaves on its way down 905 * and guarentee that the leaf it ends up on is not full. If we run out 906 * of space the search continues to the leaf (to position the cursor for 907 * the spike), but ENOSPC is returned. 908 * 909 * The search is only guarenteed to end up on a leaf if an error code of 0 910 * is returned, or if inserting and an error code of ENOENT is returned. 911 * Otherwise it can stop at an internal node. On success a search returns 912 * a leaf node. 913 * 914 * COMPLEXITY WARNING! This is the core B-Tree search code for the entire 915 * filesystem, and it is not simple code. Please note the following facts: 916 * 917 * - Internal node recursions have a boundary on the left AND right. The 918 * right boundary is non-inclusive. The create_tid is a generic part 919 * of the key for internal nodes. 920 * 921 * - Leaf nodes contain terminal elements only now. 922 * 923 * - Filesystem lookups typically set HAMMER_CURSOR_ASOF, indicating a 924 * historical search. ASOF and INSERT are mutually exclusive. When 925 * doing an as-of lookup btree_search() checks for a right-edge boundary 926 * case. If while recursing down the left-edge differs from the key 927 * by ONLY its create_tid, HAMMER_CURSOR_CREATE_CHECK is set along 928 * with cursor->create_check. This is used by btree_lookup() to iterate. 929 * The iteration backwards because as-of searches can wind up going 930 * down the wrong branch of the B-Tree. 931 */ 932 static 933 int 934 btree_search(hammer_cursor_t cursor, int flags) 935 { 936 hammer_node_ondisk_t node; 937 hammer_btree_elm_t elm; 938 int error; 939 int enospc = 0; 940 int i; 941 int r; 942 int s; 943 944 flags |= cursor->flags; 945 ++hammer_stats_btree_searches; 946 947 if (hammer_debug_btree) { 948 kprintf("SEARCH %016llx[%d] %016llx %02x key=%016llx cre=%016llx lo=%02x (td = %p)\n", 949 cursor->node->node_offset, 950 cursor->index, 951 cursor->key_beg.obj_id, 952 cursor->key_beg.rec_type, 953 cursor->key_beg.key, 954 cursor->key_beg.create_tid, 955 cursor->key_beg.localization, 956 curthread 957 ); 958 if (cursor->parent) 959 kprintf("SEARCHP %016llx[%d] (%016llx/%016llx %016llx/%016llx) (%p/%p %p/%p)\n", 960 cursor->parent->node_offset, cursor->parent_index, 961 cursor->left_bound->obj_id, 962 cursor->parent->ondisk->elms[cursor->parent_index].internal.base.obj_id, 963 cursor->right_bound->obj_id, 964 cursor->parent->ondisk->elms[cursor->parent_index+1].internal.base.obj_id, 965 cursor->left_bound, 966 &cursor->parent->ondisk->elms[cursor->parent_index], 967 cursor->right_bound, 968 &cursor->parent->ondisk->elms[cursor->parent_index+1] 969 ); 970 } 971 972 /* 973 * Move our cursor up the tree until we find a node whos range covers 974 * the key we are trying to locate. 975 * 976 * The left bound is inclusive, the right bound is non-inclusive. 977 * It is ok to cursor up too far. 978 */ 979 for (;;) { 980 r = hammer_btree_cmp(&cursor->key_beg, cursor->left_bound); 981 s = hammer_btree_cmp(&cursor->key_beg, cursor->right_bound); 982 if (r >= 0 && s < 0) 983 break; 984 KKASSERT(cursor->parent); 985 ++hammer_stats_btree_iterations; 986 error = hammer_cursor_up(cursor); 987 if (error) 988 goto done; 989 } 990 991 /* 992 * The delete-checks below are based on node, not parent. Set the 993 * initial delete-check based on the parent. 994 */ 995 if (r == 1) { 996 KKASSERT(cursor->left_bound->create_tid != 1); 997 cursor->create_check = cursor->left_bound->create_tid - 1; 998 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK; 999 } 1000 1001 /* 1002 * We better have ended up with a node somewhere. 1003 */ 1004 KKASSERT(cursor->node != NULL); 1005 1006 /* 1007 * If we are inserting we can't start at a full node if the parent 1008 * is also full (because there is no way to split the node), 1009 * continue running up the tree until the requirement is satisfied 1010 * or we hit the root of the filesystem. 1011 * 1012 * (If inserting we aren't doing an as-of search so we don't have 1013 * to worry about create_check). 1014 */ 1015 while ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) { 1016 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 1017 if (btree_node_is_full(cursor->node->ondisk) == 0) 1018 break; 1019 } else { 1020 if (btree_node_is_full(cursor->node->ondisk) ==0) 1021 break; 1022 } 1023 if (cursor->node->ondisk->parent == 0 || 1024 cursor->parent->ondisk->count != HAMMER_BTREE_INT_ELMS) { 1025 break; 1026 } 1027 ++hammer_stats_btree_iterations; 1028 error = hammer_cursor_up(cursor); 1029 /* node may have become stale */ 1030 if (error) 1031 goto done; 1032 } 1033 1034 /* 1035 * Push down through internal nodes to locate the requested key. 1036 */ 1037 node = cursor->node->ondisk; 1038 while (node->type == HAMMER_BTREE_TYPE_INTERNAL) { 1039 /* 1040 * Scan the node to find the subtree index to push down into. 1041 * We go one-past, then back-up. 1042 * 1043 * We must proactively remove deleted elements which may 1044 * have been left over from a deadlocked btree_remove(). 1045 * 1046 * The left and right boundaries are included in the loop 1047 * in order to detect edge cases. 1048 * 1049 * If the separator only differs by create_tid (r == 1) 1050 * and we are doing an as-of search, we may end up going 1051 * down a branch to the left of the one containing the 1052 * desired key. This requires numerous special cases. 1053 */ 1054 ++hammer_stats_btree_iterations; 1055 if (hammer_debug_btree) { 1056 kprintf("SEARCH-I %016llx count=%d\n", 1057 cursor->node->node_offset, 1058 node->count); 1059 } 1060 1061 /* 1062 * Try to shortcut the search before dropping into the 1063 * linear loop. Locate the first node where r <= 1. 1064 */ 1065 i = hammer_btree_search_node(&cursor->key_beg, node); 1066 while (i <= node->count) { 1067 ++hammer_stats_btree_elements; 1068 elm = &node->elms[i]; 1069 r = hammer_btree_cmp(&cursor->key_beg, &elm->base); 1070 if (hammer_debug_btree > 2) { 1071 kprintf(" IELM %p %d r=%d\n", 1072 &node->elms[i], i, r); 1073 } 1074 if (r < 0) 1075 break; 1076 if (r == 1) { 1077 KKASSERT(elm->base.create_tid != 1); 1078 cursor->create_check = elm->base.create_tid - 1; 1079 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK; 1080 } 1081 ++i; 1082 } 1083 if (hammer_debug_btree) { 1084 kprintf("SEARCH-I preI=%d/%d r=%d\n", 1085 i, node->count, r); 1086 } 1087 1088 /* 1089 * These cases occur when the parent's idea of the boundary 1090 * is wider then the child's idea of the boundary, and 1091 * require special handling. If not inserting we can 1092 * terminate the search early for these cases but the 1093 * child's boundaries cannot be unconditionally modified. 1094 */ 1095 if (i == 0) { 1096 /* 1097 * If i == 0 the search terminated to the LEFT of the 1098 * left_boundary but to the RIGHT of the parent's left 1099 * boundary. 1100 */ 1101 u_int8_t save; 1102 1103 elm = &node->elms[0]; 1104 1105 /* 1106 * If we aren't inserting we can stop here. 1107 */ 1108 if ((flags & (HAMMER_CURSOR_INSERT | 1109 HAMMER_CURSOR_PRUNING)) == 0) { 1110 cursor->index = 0; 1111 return(ENOENT); 1112 } 1113 1114 /* 1115 * Correct a left-hand boundary mismatch. 1116 * 1117 * We can only do this if we can upgrade the lock, 1118 * and synchronized as a background cursor (i.e. 1119 * inserting or pruning). 1120 * 1121 * WARNING: We can only do this if inserting, i.e. 1122 * we are running on the backend. 1123 */ 1124 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1125 return(error); 1126 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND); 1127 hammer_modify_node_field(cursor->trans, cursor->node, 1128 elms[0]); 1129 save = node->elms[0].base.btype; 1130 node->elms[0].base = *cursor->left_bound; 1131 node->elms[0].base.btype = save; 1132 hammer_modify_node_done(cursor->node); 1133 } else if (i == node->count + 1) { 1134 /* 1135 * If i == node->count + 1 the search terminated to 1136 * the RIGHT of the right boundary but to the LEFT 1137 * of the parent's right boundary. If we aren't 1138 * inserting we can stop here. 1139 * 1140 * Note that the last element in this case is 1141 * elms[i-2] prior to adjustments to 'i'. 1142 */ 1143 --i; 1144 if ((flags & (HAMMER_CURSOR_INSERT | 1145 HAMMER_CURSOR_PRUNING)) == 0) { 1146 cursor->index = i; 1147 return (ENOENT); 1148 } 1149 1150 /* 1151 * Correct a right-hand boundary mismatch. 1152 * (actual push-down record is i-2 prior to 1153 * adjustments to i). 1154 * 1155 * We can only do this if we can upgrade the lock, 1156 * and synchronized as a background cursor (i.e. 1157 * inserting or pruning). 1158 * 1159 * WARNING: We can only do this if inserting, i.e. 1160 * we are running on the backend. 1161 */ 1162 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1163 return(error); 1164 elm = &node->elms[i]; 1165 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND); 1166 hammer_modify_node(cursor->trans, cursor->node, 1167 &elm->base, sizeof(elm->base)); 1168 elm->base = *cursor->right_bound; 1169 hammer_modify_node_done(cursor->node); 1170 --i; 1171 } else { 1172 /* 1173 * The push-down index is now i - 1. If we had 1174 * terminated on the right boundary this will point 1175 * us at the last element. 1176 */ 1177 --i; 1178 } 1179 cursor->index = i; 1180 elm = &node->elms[i]; 1181 1182 if (hammer_debug_btree) { 1183 kprintf("RESULT-I %016llx[%d] %016llx %02x " 1184 "key=%016llx cre=%016llx lo=%02x\n", 1185 cursor->node->node_offset, 1186 i, 1187 elm->internal.base.obj_id, 1188 elm->internal.base.rec_type, 1189 elm->internal.base.key, 1190 elm->internal.base.create_tid, 1191 elm->internal.base.localization 1192 ); 1193 } 1194 1195 /* 1196 * We better have a valid subtree offset. 1197 */ 1198 KKASSERT(elm->internal.subtree_offset != 0); 1199 1200 /* 1201 * Handle insertion and deletion requirements. 1202 * 1203 * If inserting split full nodes. The split code will 1204 * adjust cursor->node and cursor->index if the current 1205 * index winds up in the new node. 1206 * 1207 * If inserting and a left or right edge case was detected, 1208 * we cannot correct the left or right boundary and must 1209 * prepend and append an empty leaf node in order to make 1210 * the boundary correction. 1211 * 1212 * If we run out of space we set enospc and continue on 1213 * to a leaf to provide the spike code with a good point 1214 * of entry. 1215 */ 1216 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) { 1217 if (btree_node_is_full(node)) { 1218 error = btree_split_internal(cursor); 1219 if (error) { 1220 if (error != ENOSPC) 1221 goto done; 1222 enospc = 1; 1223 } 1224 /* 1225 * reload stale pointers 1226 */ 1227 i = cursor->index; 1228 node = cursor->node->ondisk; 1229 } 1230 } 1231 1232 /* 1233 * Push down (push into new node, existing node becomes 1234 * the parent) and continue the search. 1235 */ 1236 error = hammer_cursor_down(cursor); 1237 /* node may have become stale */ 1238 if (error) 1239 goto done; 1240 node = cursor->node->ondisk; 1241 } 1242 1243 /* 1244 * We are at a leaf, do a linear search of the key array. 1245 * 1246 * On success the index is set to the matching element and 0 1247 * is returned. 1248 * 1249 * On failure the index is set to the insertion point and ENOENT 1250 * is returned. 1251 * 1252 * Boundaries are not stored in leaf nodes, so the index can wind 1253 * up to the left of element 0 (index == 0) or past the end of 1254 * the array (index == node->count). It is also possible that the 1255 * leaf might be empty. 1256 */ 1257 ++hammer_stats_btree_iterations; 1258 KKASSERT (node->type == HAMMER_BTREE_TYPE_LEAF); 1259 KKASSERT(node->count <= HAMMER_BTREE_LEAF_ELMS); 1260 if (hammer_debug_btree) { 1261 kprintf("SEARCH-L %016llx count=%d\n", 1262 cursor->node->node_offset, 1263 node->count); 1264 } 1265 1266 /* 1267 * Try to shortcut the search before dropping into the 1268 * linear loop. Locate the first node where r <= 1. 1269 */ 1270 i = hammer_btree_search_node(&cursor->key_beg, node); 1271 while (i < node->count) { 1272 ++hammer_stats_btree_elements; 1273 elm = &node->elms[i]; 1274 1275 r = hammer_btree_cmp(&cursor->key_beg, &elm->leaf.base); 1276 1277 if (hammer_debug_btree > 1) 1278 kprintf(" ELM %p %d r=%d\n", &node->elms[i], i, r); 1279 1280 /* 1281 * We are at a record element. Stop if we've flipped past 1282 * key_beg, not counting the create_tid test. Allow the 1283 * r == 1 case (key_beg > element but differs only by its 1284 * create_tid) to fall through to the AS-OF check. 1285 */ 1286 KKASSERT (elm->leaf.base.btype == HAMMER_BTREE_TYPE_RECORD); 1287 1288 if (r < 0) 1289 goto failed; 1290 if (r > 1) { 1291 ++i; 1292 continue; 1293 } 1294 1295 /* 1296 * Check our as-of timestamp against the element. 1297 */ 1298 if (flags & HAMMER_CURSOR_ASOF) { 1299 if (hammer_btree_chkts(cursor->asof, 1300 &node->elms[i].base) != 0) { 1301 ++i; 1302 continue; 1303 } 1304 /* success */ 1305 } else { 1306 if (r > 0) { /* can only be +1 */ 1307 ++i; 1308 continue; 1309 } 1310 /* success */ 1311 } 1312 cursor->index = i; 1313 error = 0; 1314 if (hammer_debug_btree) { 1315 kprintf("RESULT-L %016llx[%d] (SUCCESS)\n", 1316 cursor->node->node_offset, i); 1317 } 1318 goto done; 1319 } 1320 1321 /* 1322 * The search of the leaf node failed. i is the insertion point. 1323 */ 1324 failed: 1325 if (hammer_debug_btree) { 1326 kprintf("RESULT-L %016llx[%d] (FAILED)\n", 1327 cursor->node->node_offset, i); 1328 } 1329 1330 /* 1331 * No exact match was found, i is now at the insertion point. 1332 * 1333 * If inserting split a full leaf before returning. This 1334 * may have the side effect of adjusting cursor->node and 1335 * cursor->index. 1336 */ 1337 cursor->index = i; 1338 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0 && 1339 btree_node_is_full(node)) { 1340 error = btree_split_leaf(cursor); 1341 if (error) { 1342 if (error != ENOSPC) 1343 goto done; 1344 enospc = 1; 1345 } 1346 /* 1347 * reload stale pointers 1348 */ 1349 /* NOT USED 1350 i = cursor->index; 1351 node = &cursor->node->internal; 1352 */ 1353 } 1354 1355 /* 1356 * We reached a leaf but did not find the key we were looking for. 1357 * If this is an insert we will be properly positioned for an insert 1358 * (ENOENT) or spike (ENOSPC) operation. 1359 */ 1360 error = enospc ? ENOSPC : ENOENT; 1361 done: 1362 return(error); 1363 } 1364 1365 /* 1366 * Heuristical search for the first element whos comparison is <= 1. May 1367 * return an index whos compare result is > 1 but may only return an index 1368 * whos compare result is <= 1 if it is the first element with that result. 1369 */ 1370 int 1371 hammer_btree_search_node(hammer_base_elm_t elm, hammer_node_ondisk_t node) 1372 { 1373 int b; 1374 int s; 1375 int i; 1376 int r; 1377 1378 /* 1379 * Don't bother if the node does not have very many elements 1380 */ 1381 b = 0; 1382 s = node->count; 1383 while (s - b > 4) { 1384 i = b + (s - b) / 2; 1385 ++hammer_stats_btree_elements; 1386 r = hammer_btree_cmp(elm, &node->elms[i].leaf.base); 1387 if (r <= 1) { 1388 s = i; 1389 } else { 1390 b = i; 1391 } 1392 } 1393 return(b); 1394 } 1395 1396 1397 /************************************************************************ 1398 * SPLITTING AND MERGING * 1399 ************************************************************************ 1400 * 1401 * These routines do all the dirty work required to split and merge nodes. 1402 */ 1403 1404 /* 1405 * Split an internal node into two nodes and move the separator at the split 1406 * point to the parent. 1407 * 1408 * (cursor->node, cursor->index) indicates the element the caller intends 1409 * to push into. We will adjust node and index if that element winds 1410 * up in the split node. 1411 * 1412 * If we are at the root of the filesystem a new root must be created with 1413 * two elements, one pointing to the original root and one pointing to the 1414 * newly allocated split node. 1415 */ 1416 static 1417 int 1418 btree_split_internal(hammer_cursor_t cursor) 1419 { 1420 hammer_node_ondisk_t ondisk; 1421 hammer_node_t node; 1422 hammer_node_t parent; 1423 hammer_node_t new_node; 1424 hammer_btree_elm_t elm; 1425 hammer_btree_elm_t parent_elm; 1426 struct hammer_node_lock lockroot; 1427 hammer_mount_t hmp = cursor->trans->hmp; 1428 int parent_index; 1429 int made_root; 1430 int split; 1431 int error; 1432 int i; 1433 const int esize = sizeof(*elm); 1434 1435 hammer_node_lock_init(&lockroot, cursor->node); 1436 error = hammer_btree_lock_children(cursor, 1, &lockroot); 1437 if (error) 1438 goto done; 1439 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1440 goto done; 1441 ++hammer_stats_btree_splits; 1442 1443 /* 1444 * We are splitting but elms[split] will be promoted to the parent, 1445 * leaving the right hand node with one less element. If the 1446 * insertion point will be on the left-hand side adjust the split 1447 * point to give the right hand side one additional node. 1448 */ 1449 node = cursor->node; 1450 ondisk = node->ondisk; 1451 split = (ondisk->count + 1) / 2; 1452 if (cursor->index <= split) 1453 --split; 1454 1455 /* 1456 * If we are at the root of the filesystem, create a new root node 1457 * with 1 element and split normally. Avoid making major 1458 * modifications until we know the whole operation will work. 1459 */ 1460 if (ondisk->parent == 0) { 1461 parent = hammer_alloc_btree(cursor->trans, &error); 1462 if (parent == NULL) 1463 goto done; 1464 hammer_lock_ex(&parent->lock); 1465 hammer_modify_node_noundo(cursor->trans, parent); 1466 ondisk = parent->ondisk; 1467 ondisk->count = 1; 1468 ondisk->parent = 0; 1469 ondisk->mirror_tid = node->ondisk->mirror_tid; 1470 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1471 ondisk->elms[0].base = hmp->root_btree_beg; 1472 ondisk->elms[0].base.btype = node->ondisk->type; 1473 ondisk->elms[0].internal.subtree_offset = node->node_offset; 1474 ondisk->elms[1].base = hmp->root_btree_end; 1475 hammer_modify_node_done(parent); 1476 /* ondisk->elms[1].base.btype - not used */ 1477 made_root = 1; 1478 parent_index = 0; /* index of current node in parent */ 1479 } else { 1480 made_root = 0; 1481 parent = cursor->parent; 1482 parent_index = cursor->parent_index; 1483 } 1484 1485 /* 1486 * Split node into new_node at the split point. 1487 * 1488 * B O O O P N N B <-- P = node->elms[split] 1489 * 0 1 2 3 4 5 6 <-- subtree indices 1490 * 1491 * x x P x x 1492 * s S S s 1493 * / \ 1494 * B O O O B B N N B <--- inner boundary points are 'P' 1495 * 0 1 2 3 4 5 6 1496 * 1497 */ 1498 new_node = hammer_alloc_btree(cursor->trans, &error); 1499 if (new_node == NULL) { 1500 if (made_root) { 1501 hammer_unlock(&parent->lock); 1502 hammer_delete_node(cursor->trans, parent); 1503 hammer_rel_node(parent); 1504 } 1505 goto done; 1506 } 1507 hammer_lock_ex(&new_node->lock); 1508 1509 /* 1510 * Create the new node. P becomes the left-hand boundary in the 1511 * new node. Copy the right-hand boundary as well. 1512 * 1513 * elm is the new separator. 1514 */ 1515 hammer_modify_node_noundo(cursor->trans, new_node); 1516 hammer_modify_node_all(cursor->trans, node); 1517 ondisk = node->ondisk; 1518 elm = &ondisk->elms[split]; 1519 bcopy(elm, &new_node->ondisk->elms[0], 1520 (ondisk->count - split + 1) * esize); 1521 new_node->ondisk->count = ondisk->count - split; 1522 new_node->ondisk->parent = parent->node_offset; 1523 new_node->ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1524 new_node->ondisk->mirror_tid = ondisk->mirror_tid; 1525 KKASSERT(ondisk->type == new_node->ondisk->type); 1526 hammer_cursor_split_node(node, new_node, split); 1527 1528 /* 1529 * Cleanup the original node. Elm (P) becomes the new boundary, 1530 * its subtree_offset was moved to the new node. If we had created 1531 * a new root its parent pointer may have changed. 1532 */ 1533 elm->internal.subtree_offset = 0; 1534 ondisk->count = split; 1535 1536 /* 1537 * Insert the separator into the parent, fixup the parent's 1538 * reference to the original node, and reference the new node. 1539 * The separator is P. 1540 * 1541 * Remember that base.count does not include the right-hand boundary. 1542 */ 1543 hammer_modify_node_all(cursor->trans, parent); 1544 ondisk = parent->ondisk; 1545 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS); 1546 parent_elm = &ondisk->elms[parent_index+1]; 1547 bcopy(parent_elm, parent_elm + 1, 1548 (ondisk->count - parent_index) * esize); 1549 parent_elm->internal.base = elm->base; /* separator P */ 1550 parent_elm->internal.base.btype = new_node->ondisk->type; 1551 parent_elm->internal.subtree_offset = new_node->node_offset; 1552 parent_elm->internal.mirror_tid = new_node->ondisk->mirror_tid; 1553 ++ondisk->count; 1554 hammer_modify_node_done(parent); 1555 hammer_cursor_inserted_element(parent, parent_index + 1); 1556 1557 /* 1558 * The children of new_node need their parent pointer set to new_node. 1559 * The children have already been locked by 1560 * hammer_btree_lock_children(). 1561 */ 1562 for (i = 0; i < new_node->ondisk->count; ++i) { 1563 elm = &new_node->ondisk->elms[i]; 1564 error = btree_set_parent(cursor->trans, new_node, elm); 1565 if (error) { 1566 panic("btree_split_internal: btree-fixup problem"); 1567 } 1568 } 1569 hammer_modify_node_done(new_node); 1570 1571 /* 1572 * The filesystem's root B-Tree pointer may have to be updated. 1573 */ 1574 if (made_root) { 1575 hammer_volume_t volume; 1576 1577 volume = hammer_get_root_volume(hmp, &error); 1578 KKASSERT(error == 0); 1579 1580 hammer_modify_volume_field(cursor->trans, volume, 1581 vol0_btree_root); 1582 volume->ondisk->vol0_btree_root = parent->node_offset; 1583 hammer_modify_volume_done(volume); 1584 node->ondisk->parent = parent->node_offset; 1585 if (cursor->parent) { 1586 hammer_unlock(&cursor->parent->lock); 1587 hammer_rel_node(cursor->parent); 1588 } 1589 cursor->parent = parent; /* lock'd and ref'd */ 1590 hammer_rel_volume(volume, 0); 1591 } 1592 hammer_modify_node_done(node); 1593 1594 /* 1595 * Ok, now adjust the cursor depending on which element the original 1596 * index was pointing at. If we are >= the split point the push node 1597 * is now in the new node. 1598 * 1599 * NOTE: If we are at the split point itself we cannot stay with the 1600 * original node because the push index will point at the right-hand 1601 * boundary, which is illegal. 1602 * 1603 * NOTE: The cursor's parent or parent_index must be adjusted for 1604 * the case where a new parent (new root) was created, and the case 1605 * where the cursor is now pointing at the split node. 1606 */ 1607 if (cursor->index >= split) { 1608 cursor->parent_index = parent_index + 1; 1609 cursor->index -= split; 1610 hammer_unlock(&cursor->node->lock); 1611 hammer_rel_node(cursor->node); 1612 cursor->node = new_node; /* locked and ref'd */ 1613 } else { 1614 cursor->parent_index = parent_index; 1615 hammer_unlock(&new_node->lock); 1616 hammer_rel_node(new_node); 1617 } 1618 1619 /* 1620 * Fixup left and right bounds 1621 */ 1622 parent_elm = &parent->ondisk->elms[cursor->parent_index]; 1623 cursor->left_bound = &parent_elm[0].internal.base; 1624 cursor->right_bound = &parent_elm[1].internal.base; 1625 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1626 &cursor->node->ondisk->elms[0].internal.base) <= 0); 1627 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1628 &cursor->node->ondisk->elms[cursor->node->ondisk->count].internal.base) >= 0); 1629 1630 done: 1631 hammer_btree_unlock_children(cursor, &lockroot); 1632 hammer_cursor_downgrade(cursor); 1633 return (error); 1634 } 1635 1636 /* 1637 * Same as the above, but splits a full leaf node. 1638 * 1639 * This function 1640 */ 1641 static 1642 int 1643 btree_split_leaf(hammer_cursor_t cursor) 1644 { 1645 hammer_node_ondisk_t ondisk; 1646 hammer_node_t parent; 1647 hammer_node_t leaf; 1648 hammer_mount_t hmp; 1649 hammer_node_t new_leaf; 1650 hammer_btree_elm_t elm; 1651 hammer_btree_elm_t parent_elm; 1652 hammer_base_elm_t mid_boundary; 1653 int parent_index; 1654 int made_root; 1655 int split; 1656 int error; 1657 const size_t esize = sizeof(*elm); 1658 1659 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1660 return(error); 1661 ++hammer_stats_btree_splits; 1662 1663 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1664 &cursor->node->ondisk->elms[0].leaf.base) <= 0); 1665 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1666 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0); 1667 1668 /* 1669 * Calculate the split point. If the insertion point will be on 1670 * the left-hand side adjust the split point to give the right 1671 * hand side one additional node. 1672 * 1673 * Spikes are made up of two leaf elements which cannot be 1674 * safely split. 1675 */ 1676 leaf = cursor->node; 1677 ondisk = leaf->ondisk; 1678 split = (ondisk->count + 1) / 2; 1679 if (cursor->index <= split) 1680 --split; 1681 error = 0; 1682 hmp = leaf->hmp; 1683 1684 elm = &ondisk->elms[split]; 1685 1686 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm[-1].leaf.base) <= 0); 1687 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->leaf.base) <= 0); 1688 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->leaf.base) > 0); 1689 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm[1].leaf.base) > 0); 1690 1691 /* 1692 * If we are at the root of the tree, create a new root node with 1693 * 1 element and split normally. Avoid making major modifications 1694 * until we know the whole operation will work. 1695 */ 1696 if (ondisk->parent == 0) { 1697 parent = hammer_alloc_btree(cursor->trans, &error); 1698 if (parent == NULL) 1699 goto done; 1700 hammer_lock_ex(&parent->lock); 1701 hammer_modify_node_noundo(cursor->trans, parent); 1702 ondisk = parent->ondisk; 1703 ondisk->count = 1; 1704 ondisk->parent = 0; 1705 ondisk->mirror_tid = leaf->ondisk->mirror_tid; 1706 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1707 ondisk->elms[0].base = hmp->root_btree_beg; 1708 ondisk->elms[0].base.btype = leaf->ondisk->type; 1709 ondisk->elms[0].internal.subtree_offset = leaf->node_offset; 1710 ondisk->elms[1].base = hmp->root_btree_end; 1711 /* ondisk->elms[1].base.btype = not used */ 1712 hammer_modify_node_done(parent); 1713 made_root = 1; 1714 parent_index = 0; /* insertion point in parent */ 1715 } else { 1716 made_root = 0; 1717 parent = cursor->parent; 1718 parent_index = cursor->parent_index; 1719 } 1720 1721 /* 1722 * Split leaf into new_leaf at the split point. Select a separator 1723 * value in-between the two leafs but with a bent towards the right 1724 * leaf since comparisons use an 'elm >= separator' inequality. 1725 * 1726 * L L L L L L L L 1727 * 1728 * x x P x x 1729 * s S S s 1730 * / \ 1731 * L L L L L L L L 1732 */ 1733 new_leaf = hammer_alloc_btree(cursor->trans, &error); 1734 if (new_leaf == NULL) { 1735 if (made_root) { 1736 hammer_unlock(&parent->lock); 1737 hammer_delete_node(cursor->trans, parent); 1738 hammer_rel_node(parent); 1739 } 1740 goto done; 1741 } 1742 hammer_lock_ex(&new_leaf->lock); 1743 1744 /* 1745 * Create the new node and copy the leaf elements from the split 1746 * point on to the new node. 1747 */ 1748 hammer_modify_node_all(cursor->trans, leaf); 1749 hammer_modify_node_noundo(cursor->trans, new_leaf); 1750 ondisk = leaf->ondisk; 1751 elm = &ondisk->elms[split]; 1752 bcopy(elm, &new_leaf->ondisk->elms[0], (ondisk->count - split) * esize); 1753 new_leaf->ondisk->count = ondisk->count - split; 1754 new_leaf->ondisk->parent = parent->node_offset; 1755 new_leaf->ondisk->type = HAMMER_BTREE_TYPE_LEAF; 1756 new_leaf->ondisk->mirror_tid = ondisk->mirror_tid; 1757 KKASSERT(ondisk->type == new_leaf->ondisk->type); 1758 hammer_modify_node_done(new_leaf); 1759 hammer_cursor_split_node(leaf, new_leaf, split); 1760 1761 /* 1762 * Cleanup the original node. Because this is a leaf node and 1763 * leaf nodes do not have a right-hand boundary, there 1764 * aren't any special edge cases to clean up. We just fixup the 1765 * count. 1766 */ 1767 ondisk->count = split; 1768 1769 /* 1770 * Insert the separator into the parent, fixup the parent's 1771 * reference to the original node, and reference the new node. 1772 * The separator is P. 1773 * 1774 * Remember that base.count does not include the right-hand boundary. 1775 * We are copying parent_index+1 to parent_index+2, not +0 to +1. 1776 */ 1777 hammer_modify_node_all(cursor->trans, parent); 1778 ondisk = parent->ondisk; 1779 KKASSERT(split != 0); 1780 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS); 1781 parent_elm = &ondisk->elms[parent_index+1]; 1782 bcopy(parent_elm, parent_elm + 1, 1783 (ondisk->count - parent_index) * esize); 1784 1785 hammer_make_separator(&elm[-1].base, &elm[0].base, &parent_elm->base); 1786 parent_elm->internal.base.btype = new_leaf->ondisk->type; 1787 parent_elm->internal.subtree_offset = new_leaf->node_offset; 1788 parent_elm->internal.mirror_tid = new_leaf->ondisk->mirror_tid; 1789 mid_boundary = &parent_elm->base; 1790 ++ondisk->count; 1791 hammer_modify_node_done(parent); 1792 hammer_cursor_inserted_element(parent, parent_index + 1); 1793 1794 /* 1795 * The filesystem's root B-Tree pointer may have to be updated. 1796 */ 1797 if (made_root) { 1798 hammer_volume_t volume; 1799 1800 volume = hammer_get_root_volume(hmp, &error); 1801 KKASSERT(error == 0); 1802 1803 hammer_modify_volume_field(cursor->trans, volume, 1804 vol0_btree_root); 1805 volume->ondisk->vol0_btree_root = parent->node_offset; 1806 hammer_modify_volume_done(volume); 1807 leaf->ondisk->parent = parent->node_offset; 1808 if (cursor->parent) { 1809 hammer_unlock(&cursor->parent->lock); 1810 hammer_rel_node(cursor->parent); 1811 } 1812 cursor->parent = parent; /* lock'd and ref'd */ 1813 hammer_rel_volume(volume, 0); 1814 } 1815 hammer_modify_node_done(leaf); 1816 1817 /* 1818 * Ok, now adjust the cursor depending on which element the original 1819 * index was pointing at. If we are >= the split point the push node 1820 * is now in the new node. 1821 * 1822 * NOTE: If we are at the split point itself we need to select the 1823 * old or new node based on where key_beg's insertion point will be. 1824 * If we pick the wrong side the inserted element will wind up in 1825 * the wrong leaf node and outside that node's bounds. 1826 */ 1827 if (cursor->index > split || 1828 (cursor->index == split && 1829 hammer_btree_cmp(&cursor->key_beg, mid_boundary) >= 0)) { 1830 cursor->parent_index = parent_index + 1; 1831 cursor->index -= split; 1832 hammer_unlock(&cursor->node->lock); 1833 hammer_rel_node(cursor->node); 1834 cursor->node = new_leaf; 1835 } else { 1836 cursor->parent_index = parent_index; 1837 hammer_unlock(&new_leaf->lock); 1838 hammer_rel_node(new_leaf); 1839 } 1840 1841 /* 1842 * Fixup left and right bounds 1843 */ 1844 parent_elm = &parent->ondisk->elms[cursor->parent_index]; 1845 cursor->left_bound = &parent_elm[0].internal.base; 1846 cursor->right_bound = &parent_elm[1].internal.base; 1847 1848 /* 1849 * Assert that the bounds are correct. 1850 */ 1851 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1852 &cursor->node->ondisk->elms[0].leaf.base) <= 0); 1853 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1854 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0); 1855 KKASSERT(hammer_btree_cmp(cursor->left_bound, &cursor->key_beg) <= 0); 1856 KKASSERT(hammer_btree_cmp(cursor->right_bound, &cursor->key_beg) > 0); 1857 1858 done: 1859 hammer_cursor_downgrade(cursor); 1860 return (error); 1861 } 1862 1863 #if 0 1864 1865 /* 1866 * Recursively correct the right-hand boundary's create_tid to (tid) as 1867 * long as the rest of the key matches. We have to recurse upward in 1868 * the tree as well as down the left side of each parent's right node. 1869 * 1870 * Return EDEADLK if we were only partially successful, forcing the caller 1871 * to try again. The original cursor is not modified. This routine can 1872 * also fail with EDEADLK if it is forced to throw away a portion of its 1873 * record history. 1874 * 1875 * The caller must pass a downgraded cursor to us (otherwise we can't dup it). 1876 */ 1877 struct hammer_rhb { 1878 TAILQ_ENTRY(hammer_rhb) entry; 1879 hammer_node_t node; 1880 int index; 1881 }; 1882 1883 TAILQ_HEAD(hammer_rhb_list, hammer_rhb); 1884 1885 int 1886 hammer_btree_correct_rhb(hammer_cursor_t cursor, hammer_tid_t tid) 1887 { 1888 struct hammer_mount *hmp; 1889 struct hammer_rhb_list rhb_list; 1890 hammer_base_elm_t elm; 1891 hammer_node_t orig_node; 1892 struct hammer_rhb *rhb; 1893 int orig_index; 1894 int error; 1895 1896 TAILQ_INIT(&rhb_list); 1897 hmp = cursor->trans->hmp; 1898 1899 /* 1900 * Save our position so we can restore it on return. This also 1901 * gives us a stable 'elm'. 1902 */ 1903 orig_node = cursor->node; 1904 hammer_ref_node(orig_node); 1905 hammer_lock_sh(&orig_node->lock); 1906 orig_index = cursor->index; 1907 elm = &orig_node->ondisk->elms[orig_index].base; 1908 1909 /* 1910 * Now build a list of parents going up, allocating a rhb 1911 * structure for each one. 1912 */ 1913 while (cursor->parent) { 1914 /* 1915 * Stop if we no longer have any right-bounds to fix up 1916 */ 1917 if (elm->obj_id != cursor->right_bound->obj_id || 1918 elm->rec_type != cursor->right_bound->rec_type || 1919 elm->key != cursor->right_bound->key) { 1920 break; 1921 } 1922 1923 /* 1924 * Stop if the right-hand bound's create_tid does not 1925 * need to be corrected. 1926 */ 1927 if (cursor->right_bound->create_tid >= tid) 1928 break; 1929 1930 rhb = kmalloc(sizeof(*rhb), hmp->m_misc, M_WAITOK|M_ZERO); 1931 rhb->node = cursor->parent; 1932 rhb->index = cursor->parent_index; 1933 hammer_ref_node(rhb->node); 1934 hammer_lock_sh(&rhb->node->lock); 1935 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry); 1936 1937 hammer_cursor_up(cursor); 1938 } 1939 1940 /* 1941 * now safely adjust the right hand bound for each rhb. This may 1942 * also require taking the right side of the tree and iterating down 1943 * ITS left side. 1944 */ 1945 error = 0; 1946 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 1947 error = hammer_cursor_seek(cursor, rhb->node, rhb->index); 1948 if (error) 1949 break; 1950 TAILQ_REMOVE(&rhb_list, rhb, entry); 1951 hammer_unlock(&rhb->node->lock); 1952 hammer_rel_node(rhb->node); 1953 kfree(rhb, hmp->m_misc); 1954 1955 switch (cursor->node->ondisk->type) { 1956 case HAMMER_BTREE_TYPE_INTERNAL: 1957 /* 1958 * Right-boundary for parent at internal node 1959 * is one element to the right of the element whos 1960 * right boundary needs adjusting. We must then 1961 * traverse down the left side correcting any left 1962 * bounds (which may now be too far to the left). 1963 */ 1964 ++cursor->index; 1965 error = hammer_btree_correct_lhb(cursor, tid); 1966 break; 1967 default: 1968 panic("hammer_btree_correct_rhb(): Bad node type"); 1969 error = EINVAL; 1970 break; 1971 } 1972 } 1973 1974 /* 1975 * Cleanup 1976 */ 1977 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 1978 TAILQ_REMOVE(&rhb_list, rhb, entry); 1979 hammer_unlock(&rhb->node->lock); 1980 hammer_rel_node(rhb->node); 1981 kfree(rhb, hmp->m_misc); 1982 } 1983 error = hammer_cursor_seek(cursor, orig_node, orig_index); 1984 hammer_unlock(&orig_node->lock); 1985 hammer_rel_node(orig_node); 1986 return (error); 1987 } 1988 1989 /* 1990 * Similar to rhb (in fact, rhb calls lhb), but corrects the left hand 1991 * bound going downward starting at the current cursor position. 1992 * 1993 * This function does not restore the cursor after use. 1994 */ 1995 int 1996 hammer_btree_correct_lhb(hammer_cursor_t cursor, hammer_tid_t tid) 1997 { 1998 struct hammer_rhb_list rhb_list; 1999 hammer_base_elm_t elm; 2000 hammer_base_elm_t cmp; 2001 struct hammer_rhb *rhb; 2002 struct hammer_mount *hmp; 2003 int error; 2004 2005 TAILQ_INIT(&rhb_list); 2006 hmp = cursor->trans->hmp; 2007 2008 cmp = &cursor->node->ondisk->elms[cursor->index].base; 2009 2010 /* 2011 * Record the node and traverse down the left-hand side for all 2012 * matching records needing a boundary correction. 2013 */ 2014 error = 0; 2015 for (;;) { 2016 rhb = kmalloc(sizeof(*rhb), hmp->m_misc, M_WAITOK|M_ZERO); 2017 rhb->node = cursor->node; 2018 rhb->index = cursor->index; 2019 hammer_ref_node(rhb->node); 2020 hammer_lock_sh(&rhb->node->lock); 2021 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry); 2022 2023 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2024 /* 2025 * Nothing to traverse down if we are at the right 2026 * boundary of an internal node. 2027 */ 2028 if (cursor->index == cursor->node->ondisk->count) 2029 break; 2030 } else { 2031 elm = &cursor->node->ondisk->elms[cursor->index].base; 2032 if (elm->btype == HAMMER_BTREE_TYPE_RECORD) 2033 break; 2034 panic("Illegal leaf record type %02x", elm->btype); 2035 } 2036 error = hammer_cursor_down(cursor); 2037 if (error) 2038 break; 2039 2040 elm = &cursor->node->ondisk->elms[cursor->index].base; 2041 if (elm->obj_id != cmp->obj_id || 2042 elm->rec_type != cmp->rec_type || 2043 elm->key != cmp->key) { 2044 break; 2045 } 2046 if (elm->create_tid >= tid) 2047 break; 2048 2049 } 2050 2051 /* 2052 * Now we can safely adjust the left-hand boundary from the bottom-up. 2053 * The last element we remove from the list is the caller's right hand 2054 * boundary, which must also be adjusted. 2055 */ 2056 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2057 error = hammer_cursor_seek(cursor, rhb->node, rhb->index); 2058 if (error) 2059 break; 2060 TAILQ_REMOVE(&rhb_list, rhb, entry); 2061 hammer_unlock(&rhb->node->lock); 2062 hammer_rel_node(rhb->node); 2063 kfree(rhb, hmp->m_misc); 2064 2065 elm = &cursor->node->ondisk->elms[cursor->index].base; 2066 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2067 hammer_modify_node(cursor->trans, cursor->node, 2068 &elm->create_tid, 2069 sizeof(elm->create_tid)); 2070 elm->create_tid = tid; 2071 hammer_modify_node_done(cursor->node); 2072 } else { 2073 panic("hammer_btree_correct_lhb(): Bad element type"); 2074 } 2075 } 2076 2077 /* 2078 * Cleanup 2079 */ 2080 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2081 TAILQ_REMOVE(&rhb_list, rhb, entry); 2082 hammer_unlock(&rhb->node->lock); 2083 hammer_rel_node(rhb->node); 2084 kfree(rhb, hmp->m_misc); 2085 } 2086 return (error); 2087 } 2088 2089 #endif 2090 2091 /* 2092 * Attempt to remove the locked, empty or want-to-be-empty B-Tree node at 2093 * (cursor->node). Returns 0 on success, EDEADLK if we could not complete 2094 * the operation due to a deadlock, or some other error. 2095 * 2096 * This routine is initially called with an empty leaf and may be 2097 * recursively called with single-element internal nodes. 2098 * 2099 * It should also be noted that when removing empty leaves we must be sure 2100 * to test and update mirror_tid because another thread may have deadlocked 2101 * against us (or someone) trying to propagate it up and cannot retry once 2102 * the node has been deleted. 2103 * 2104 * On return the cursor may end up pointing to an internal node, suitable 2105 * for further iteration but not for an immediate insertion or deletion. 2106 */ 2107 static int 2108 btree_remove(hammer_cursor_t cursor) 2109 { 2110 hammer_node_ondisk_t ondisk; 2111 hammer_btree_elm_t elm; 2112 hammer_node_t node; 2113 hammer_node_t parent; 2114 const int esize = sizeof(*elm); 2115 int error; 2116 2117 node = cursor->node; 2118 2119 /* 2120 * When deleting the root of the filesystem convert it to 2121 * an empty leaf node. Internal nodes cannot be empty. 2122 */ 2123 ondisk = node->ondisk; 2124 if (ondisk->parent == 0) { 2125 KKASSERT(cursor->parent == NULL); 2126 hammer_modify_node_all(cursor->trans, node); 2127 KKASSERT(ondisk == node->ondisk); 2128 ondisk->type = HAMMER_BTREE_TYPE_LEAF; 2129 ondisk->count = 0; 2130 hammer_modify_node_done(node); 2131 cursor->index = 0; 2132 return(0); 2133 } 2134 2135 parent = cursor->parent; 2136 hammer_cursor_removed_node(node, parent, cursor->parent_index); 2137 2138 /* 2139 * Attempt to remove the parent's reference to the child. If the 2140 * parent would become empty we have to recurse. If we fail we 2141 * leave the parent pointing to an empty leaf node. 2142 * 2143 * We have to recurse successfully before we can delete the internal 2144 * node as it is illegal to have empty internal nodes. Even though 2145 * the operation may be aborted we must still fixup any unlocked 2146 * cursors as if we had deleted the element prior to recursing 2147 * (by calling hammer_cursor_deleted_element()) so those cursors 2148 * are properly forced up the chain by the recursion. 2149 */ 2150 if (parent->ondisk->count == 1) { 2151 /* 2152 * This special cursor_up_locked() call leaves the original 2153 * node exclusively locked and referenced, leaves the 2154 * original parent locked (as the new node), and locks the 2155 * new parent. It can return EDEADLK. 2156 */ 2157 error = hammer_cursor_up_locked(cursor); 2158 if (error == 0) { 2159 hammer_cursor_deleted_element(cursor->node, 0); 2160 error = btree_remove(cursor); 2161 if (error == 0) { 2162 hammer_modify_node_all(cursor->trans, node); 2163 ondisk = node->ondisk; 2164 ondisk->type = HAMMER_BTREE_TYPE_DELETED; 2165 ondisk->count = 0; 2166 hammer_modify_node_done(node); 2167 hammer_flush_node(node); 2168 hammer_delete_node(cursor->trans, node); 2169 } else { 2170 /* 2171 * Defer parent removal because we could not 2172 * get the lock, just let the leaf remain 2173 * empty. 2174 */ 2175 /**/ 2176 } 2177 hammer_unlock(&node->lock); 2178 hammer_rel_node(node); 2179 } else { 2180 /* 2181 * Defer parent removal because we could not 2182 * get the lock, just let the leaf remain 2183 * empty. 2184 */ 2185 /**/ 2186 } 2187 } else { 2188 KKASSERT(parent->ondisk->count > 1); 2189 2190 hammer_modify_node_all(cursor->trans, parent); 2191 ondisk = parent->ondisk; 2192 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_INTERNAL); 2193 2194 elm = &ondisk->elms[cursor->parent_index]; 2195 KKASSERT(elm->internal.subtree_offset == node->node_offset); 2196 KKASSERT(ondisk->count > 0); 2197 2198 /* 2199 * We must retain the highest mirror_tid. The deleted 2200 * range is now encompassed by the element to the left. 2201 * If we are already at the left edge the new left edge 2202 * inherits mirror_tid. 2203 * 2204 * Note that bounds of the parent to our parent may create 2205 * a gap to the left of our left-most node or to the right 2206 * of our right-most node. The gap is silently included 2207 * in the mirror_tid's area of effect from the point of view 2208 * of the scan. 2209 */ 2210 if (cursor->parent_index) { 2211 if (elm[-1].internal.mirror_tid < 2212 elm[0].internal.mirror_tid) { 2213 elm[-1].internal.mirror_tid = 2214 elm[0].internal.mirror_tid; 2215 } 2216 } else { 2217 if (elm[1].internal.mirror_tid < 2218 elm[0].internal.mirror_tid) { 2219 elm[1].internal.mirror_tid = 2220 elm[0].internal.mirror_tid; 2221 } 2222 } 2223 2224 /* 2225 * Delete the subtree reference in the parent 2226 */ 2227 bcopy(&elm[1], &elm[0], 2228 (ondisk->count - cursor->parent_index) * esize); 2229 --ondisk->count; 2230 hammer_modify_node_done(parent); 2231 hammer_cursor_deleted_element(parent, cursor->parent_index); 2232 hammer_flush_node(node); 2233 hammer_delete_node(cursor->trans, node); 2234 2235 /* 2236 * cursor->node is invalid, cursor up to make the cursor 2237 * valid again. 2238 */ 2239 error = hammer_cursor_up(cursor); 2240 } 2241 return (error); 2242 } 2243 2244 /* 2245 * Propagate cursor->trans->tid up the B-Tree starting at the current 2246 * cursor position using pseudofs info gleaned from the passed inode. 2247 * 2248 * The passed inode has no relationship to the cursor position other 2249 * then being in the same pseudofs as the insertion or deletion we 2250 * are propagating the mirror_tid for. 2251 */ 2252 void 2253 hammer_btree_do_propagation(hammer_cursor_t cursor, 2254 hammer_pseudofs_inmem_t pfsm, 2255 hammer_btree_leaf_elm_t leaf) 2256 { 2257 hammer_cursor_t ncursor; 2258 hammer_tid_t mirror_tid; 2259 int error; 2260 2261 /* 2262 * We do not propagate a mirror_tid if the filesystem was mounted 2263 * in no-mirror mode. 2264 */ 2265 if (cursor->trans->hmp->master_id < 0) 2266 return; 2267 2268 /* 2269 * This is a bit of a hack because we cannot deadlock or return 2270 * EDEADLK here. The related operation has already completed and 2271 * we must propagate the mirror_tid now regardless. 2272 * 2273 * Generate a new cursor which inherits the original's locks and 2274 * unlock the original. Use the new cursor to propagate the 2275 * mirror_tid. Then clean up the new cursor and reacquire locks 2276 * on the original. 2277 * 2278 * hammer_dup_cursor() cannot dup locks. The dup inherits the 2279 * original's locks and the original is tracked and must be 2280 * re-locked. 2281 */ 2282 mirror_tid = cursor->node->ondisk->mirror_tid; 2283 KKASSERT(mirror_tid != 0); 2284 ncursor = hammer_push_cursor(cursor); 2285 error = hammer_btree_mirror_propagate(ncursor, mirror_tid); 2286 KKASSERT(error == 0); 2287 hammer_pop_cursor(cursor, ncursor); 2288 } 2289 2290 2291 /* 2292 * Propagate a mirror TID update upwards through the B-Tree to the root. 2293 * 2294 * A locked internal node must be passed in. The node will remain locked 2295 * on return. 2296 * 2297 * This function syncs mirror_tid at the specified internal node's element, 2298 * adjusts the node's aggregation mirror_tid, and then recurses upwards. 2299 */ 2300 static int 2301 hammer_btree_mirror_propagate(hammer_cursor_t cursor, hammer_tid_t mirror_tid) 2302 { 2303 hammer_btree_internal_elm_t elm; 2304 hammer_node_t node; 2305 int error; 2306 2307 for (;;) { 2308 error = hammer_cursor_up(cursor); 2309 if (error == 0) 2310 error = hammer_cursor_upgrade(cursor); 2311 while (error == EDEADLK) { 2312 hammer_recover_cursor(cursor); 2313 error = hammer_cursor_upgrade(cursor); 2314 } 2315 if (error) 2316 break; 2317 node = cursor->node; 2318 KKASSERT (node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL); 2319 2320 /* 2321 * Adjust the node's element 2322 */ 2323 elm = &node->ondisk->elms[cursor->index].internal; 2324 if (elm->mirror_tid >= mirror_tid) 2325 break; 2326 hammer_modify_node(cursor->trans, node, &elm->mirror_tid, 2327 sizeof(elm->mirror_tid)); 2328 elm->mirror_tid = mirror_tid; 2329 hammer_modify_node_done(node); 2330 if (hammer_debug_general & 0x0002) { 2331 kprintf("mirror_propagate: propagate " 2332 "%016llx @%016llx:%d\n", 2333 mirror_tid, node->node_offset, cursor->index); 2334 } 2335 2336 2337 /* 2338 * Adjust the node's mirror_tid aggregator 2339 */ 2340 if (node->ondisk->mirror_tid >= mirror_tid) 2341 return(0); 2342 hammer_modify_node_field(cursor->trans, node, mirror_tid); 2343 node->ondisk->mirror_tid = mirror_tid; 2344 hammer_modify_node_done(node); 2345 if (hammer_debug_general & 0x0002) { 2346 kprintf("mirror_propagate: propagate " 2347 "%016llx @%016llx\n", 2348 mirror_tid, node->node_offset); 2349 } 2350 } 2351 if (error == ENOENT) 2352 error = 0; 2353 return(error); 2354 } 2355 2356 hammer_node_t 2357 hammer_btree_get_parent(hammer_transaction_t trans, hammer_node_t node, 2358 int *parent_indexp, int *errorp, int try_exclusive) 2359 { 2360 hammer_node_t parent; 2361 hammer_btree_elm_t elm; 2362 int i; 2363 2364 /* 2365 * Get the node 2366 */ 2367 parent = hammer_get_node(trans, node->ondisk->parent, 0, errorp); 2368 if (*errorp) { 2369 KKASSERT(parent == NULL); 2370 return(NULL); 2371 } 2372 KKASSERT ((parent->flags & HAMMER_NODE_DELETED) == 0); 2373 2374 /* 2375 * Lock the node 2376 */ 2377 if (try_exclusive) { 2378 if (hammer_lock_ex_try(&parent->lock)) { 2379 hammer_rel_node(parent); 2380 *errorp = EDEADLK; 2381 return(NULL); 2382 } 2383 } else { 2384 hammer_lock_sh(&parent->lock); 2385 } 2386 2387 /* 2388 * Figure out which element in the parent is pointing to the 2389 * child. 2390 */ 2391 if (node->ondisk->count) { 2392 i = hammer_btree_search_node(&node->ondisk->elms[0].base, 2393 parent->ondisk); 2394 } else { 2395 i = 0; 2396 } 2397 while (i < parent->ondisk->count) { 2398 elm = &parent->ondisk->elms[i]; 2399 if (elm->internal.subtree_offset == node->node_offset) 2400 break; 2401 ++i; 2402 } 2403 if (i == parent->ondisk->count) { 2404 hammer_unlock(&parent->lock); 2405 panic("Bad B-Tree link: parent %p node %p\n", parent, node); 2406 } 2407 *parent_indexp = i; 2408 KKASSERT(*errorp == 0); 2409 return(parent); 2410 } 2411 2412 /* 2413 * The element (elm) has been moved to a new internal node (node). 2414 * 2415 * If the element represents a pointer to an internal node that node's 2416 * parent must be adjusted to the element's new location. 2417 * 2418 * XXX deadlock potential here with our exclusive locks 2419 */ 2420 int 2421 btree_set_parent(hammer_transaction_t trans, hammer_node_t node, 2422 hammer_btree_elm_t elm) 2423 { 2424 hammer_node_t child; 2425 int error; 2426 2427 error = 0; 2428 2429 switch(elm->base.btype) { 2430 case HAMMER_BTREE_TYPE_INTERNAL: 2431 case HAMMER_BTREE_TYPE_LEAF: 2432 child = hammer_get_node(trans, elm->internal.subtree_offset, 2433 0, &error); 2434 if (error == 0) { 2435 hammer_modify_node_field(trans, child, parent); 2436 child->ondisk->parent = node->node_offset; 2437 hammer_modify_node_done(child); 2438 hammer_rel_node(child); 2439 } 2440 break; 2441 default: 2442 break; 2443 } 2444 return(error); 2445 } 2446 2447 /* 2448 * Initialize the root of a recursive B-Tree node lock list structure. 2449 */ 2450 void 2451 hammer_node_lock_init(hammer_node_lock_t parent, hammer_node_t node) 2452 { 2453 TAILQ_INIT(&parent->list); 2454 parent->parent = NULL; 2455 parent->node = node; 2456 parent->index = -1; 2457 parent->count = node->ondisk->count; 2458 parent->copy = NULL; 2459 parent->flags = 0; 2460 } 2461 2462 /* 2463 * Exclusively lock all the children of node. This is used by the split 2464 * code to prevent anyone from accessing the children of a cursor node 2465 * while we fix-up its parent offset. 2466 * 2467 * If we don't lock the children we can really mess up cursors which block 2468 * trying to cursor-up into our node. 2469 * 2470 * On failure EDEADLK (or some other error) is returned. If a deadlock 2471 * error is returned the cursor is adjusted to block on termination. 2472 * 2473 * The caller is responsible for managing parent->node, the root's node 2474 * is usually aliased from a cursor. 2475 */ 2476 int 2477 hammer_btree_lock_children(hammer_cursor_t cursor, int depth, 2478 hammer_node_lock_t parent) 2479 { 2480 hammer_node_t node; 2481 hammer_node_lock_t item; 2482 hammer_node_ondisk_t ondisk; 2483 hammer_btree_elm_t elm; 2484 hammer_node_t child; 2485 struct hammer_mount *hmp; 2486 int error; 2487 int i; 2488 2489 node = parent->node; 2490 ondisk = node->ondisk; 2491 error = 0; 2492 hmp = cursor->trans->hmp; 2493 2494 /* 2495 * We really do not want to block on I/O with exclusive locks held, 2496 * pre-get the children before trying to lock the mess. This is 2497 * only done one-level deep for now. 2498 */ 2499 for (i = 0; i < ondisk->count; ++i) { 2500 ++hammer_stats_btree_elements; 2501 elm = &ondisk->elms[i]; 2502 if (elm->base.btype != HAMMER_BTREE_TYPE_LEAF && 2503 elm->base.btype != HAMMER_BTREE_TYPE_INTERNAL) { 2504 continue; 2505 } 2506 child = hammer_get_node(cursor->trans, 2507 elm->internal.subtree_offset, 2508 0, &error); 2509 if (child) 2510 hammer_rel_node(child); 2511 } 2512 2513 /* 2514 * Do it for real 2515 */ 2516 for (i = 0; error == 0 && i < ondisk->count; ++i) { 2517 ++hammer_stats_btree_elements; 2518 elm = &ondisk->elms[i]; 2519 2520 switch(elm->base.btype) { 2521 case HAMMER_BTREE_TYPE_INTERNAL: 2522 case HAMMER_BTREE_TYPE_LEAF: 2523 KKASSERT(elm->internal.subtree_offset != 0); 2524 child = hammer_get_node(cursor->trans, 2525 elm->internal.subtree_offset, 2526 0, &error); 2527 break; 2528 default: 2529 child = NULL; 2530 break; 2531 } 2532 if (child) { 2533 if (hammer_lock_ex_try(&child->lock) != 0) { 2534 if (cursor->deadlk_node == NULL) { 2535 cursor->deadlk_node = child; 2536 hammer_ref_node(cursor->deadlk_node); 2537 } 2538 error = EDEADLK; 2539 hammer_rel_node(child); 2540 } else { 2541 item = kmalloc(sizeof(*item), hmp->m_misc, 2542 M_WAITOK|M_ZERO); 2543 TAILQ_INSERT_TAIL(&parent->list, item, entry); 2544 TAILQ_INIT(&item->list); 2545 item->parent = parent; 2546 item->node = child; 2547 item->index = i; 2548 item->count = child->ondisk->count; 2549 2550 /* 2551 * Recurse (used by the rebalancing code) 2552 */ 2553 if (depth > 1 && elm->base.btype == HAMMER_BTREE_TYPE_INTERNAL) { 2554 error = hammer_btree_lock_children( 2555 cursor, 2556 depth - 1, 2557 item); 2558 } 2559 } 2560 } 2561 } 2562 if (error) 2563 hammer_btree_unlock_children(cursor, parent); 2564 return(error); 2565 } 2566 2567 /* 2568 * Create an in-memory copy of all B-Tree nodes listed, recursively, 2569 * including the parent. 2570 */ 2571 void 2572 hammer_btree_lock_copy(hammer_cursor_t cursor, hammer_node_lock_t parent) 2573 { 2574 hammer_mount_t hmp = cursor->trans->hmp; 2575 hammer_node_lock_t item; 2576 2577 if (parent->copy == NULL) { 2578 parent->copy = kmalloc(sizeof(*parent->copy), hmp->m_misc, 2579 M_WAITOK); 2580 *parent->copy = *parent->node->ondisk; 2581 } 2582 TAILQ_FOREACH(item, &parent->list, entry) { 2583 hammer_btree_lock_copy(cursor, item); 2584 } 2585 } 2586 2587 /* 2588 * Recursively sync modified copies to the media. 2589 */ 2590 int 2591 hammer_btree_sync_copy(hammer_cursor_t cursor, hammer_node_lock_t parent) 2592 { 2593 hammer_node_lock_t item; 2594 int count = 0; 2595 2596 if (parent->flags & HAMMER_NODE_LOCK_UPDATED) { 2597 ++count; 2598 hammer_modify_node_all(cursor->trans, parent->node); 2599 *parent->node->ondisk = *parent->copy; 2600 hammer_modify_node_done(parent->node); 2601 if (parent->copy->type == HAMMER_BTREE_TYPE_DELETED) { 2602 hammer_flush_node(parent->node); 2603 hammer_delete_node(cursor->trans, parent->node); 2604 } 2605 } 2606 TAILQ_FOREACH(item, &parent->list, entry) { 2607 count += hammer_btree_sync_copy(cursor, item); 2608 } 2609 return(count); 2610 } 2611 2612 /* 2613 * Release previously obtained node locks. The caller is responsible for 2614 * cleaning up parent->node itself (its usually just aliased from a cursor), 2615 * but this function will take care of the copies. 2616 */ 2617 void 2618 hammer_btree_unlock_children(hammer_cursor_t cursor, hammer_node_lock_t parent) 2619 { 2620 hammer_node_lock_t item; 2621 2622 if (parent->copy) { 2623 kfree(parent->copy, cursor->trans->hmp->m_misc); 2624 parent->copy = NULL; /* safety */ 2625 } 2626 while ((item = TAILQ_FIRST(&parent->list)) != NULL) { 2627 TAILQ_REMOVE(&parent->list, item, entry); 2628 hammer_btree_unlock_children(cursor, item); 2629 hammer_unlock(&item->node->lock); 2630 hammer_rel_node(item->node); 2631 kfree(item, cursor->trans->hmp->m_misc); 2632 } 2633 } 2634 2635 /************************************************************************ 2636 * MISCELLANIOUS SUPPORT * 2637 ************************************************************************/ 2638 2639 /* 2640 * Compare two B-Tree elements, return -N, 0, or +N (e.g. similar to strcmp). 2641 * 2642 * Note that for this particular function a return value of -1, 0, or +1 2643 * can denote a match if create_tid is otherwise discounted. A create_tid 2644 * of zero is considered to be 'infinity' in comparisons. 2645 * 2646 * See also hammer_rec_rb_compare() and hammer_rec_cmp() in hammer_object.c. 2647 */ 2648 int 2649 hammer_btree_cmp(hammer_base_elm_t key1, hammer_base_elm_t key2) 2650 { 2651 if (key1->localization < key2->localization) 2652 return(-5); 2653 if (key1->localization > key2->localization) 2654 return(5); 2655 2656 if (key1->obj_id < key2->obj_id) 2657 return(-4); 2658 if (key1->obj_id > key2->obj_id) 2659 return(4); 2660 2661 if (key1->rec_type < key2->rec_type) 2662 return(-3); 2663 if (key1->rec_type > key2->rec_type) 2664 return(3); 2665 2666 if (key1->key < key2->key) 2667 return(-2); 2668 if (key1->key > key2->key) 2669 return(2); 2670 2671 /* 2672 * A create_tid of zero indicates a record which is undeletable 2673 * and must be considered to have a value of positive infinity. 2674 */ 2675 if (key1->create_tid == 0) { 2676 if (key2->create_tid == 0) 2677 return(0); 2678 return(1); 2679 } 2680 if (key2->create_tid == 0) 2681 return(-1); 2682 if (key1->create_tid < key2->create_tid) 2683 return(-1); 2684 if (key1->create_tid > key2->create_tid) 2685 return(1); 2686 return(0); 2687 } 2688 2689 /* 2690 * Test a timestamp against an element to determine whether the 2691 * element is visible. A timestamp of 0 means 'infinity'. 2692 */ 2693 int 2694 hammer_btree_chkts(hammer_tid_t asof, hammer_base_elm_t base) 2695 { 2696 if (asof == 0) { 2697 if (base->delete_tid) 2698 return(1); 2699 return(0); 2700 } 2701 if (asof < base->create_tid) 2702 return(-1); 2703 if (base->delete_tid && asof >= base->delete_tid) 2704 return(1); 2705 return(0); 2706 } 2707 2708 /* 2709 * Create a separator half way inbetween key1 and key2. For fields just 2710 * one unit apart, the separator will match key2. key1 is on the left-hand 2711 * side and key2 is on the right-hand side. 2712 * 2713 * key2 must be >= the separator. It is ok for the separator to match key2. 2714 * 2715 * NOTE: Even if key1 does not match key2, the separator may wind up matching 2716 * key2. 2717 * 2718 * NOTE: It might be beneficial to just scrap this whole mess and just 2719 * set the separator to key2. 2720 */ 2721 #define MAKE_SEPARATOR(key1, key2, dest, field) \ 2722 dest->field = key1->field + ((key2->field - key1->field + 1) >> 1); 2723 2724 static void 2725 hammer_make_separator(hammer_base_elm_t key1, hammer_base_elm_t key2, 2726 hammer_base_elm_t dest) 2727 { 2728 bzero(dest, sizeof(*dest)); 2729 2730 dest->rec_type = key2->rec_type; 2731 dest->key = key2->key; 2732 dest->obj_id = key2->obj_id; 2733 dest->create_tid = key2->create_tid; 2734 2735 MAKE_SEPARATOR(key1, key2, dest, localization); 2736 if (key1->localization == key2->localization) { 2737 MAKE_SEPARATOR(key1, key2, dest, obj_id); 2738 if (key1->obj_id == key2->obj_id) { 2739 MAKE_SEPARATOR(key1, key2, dest, rec_type); 2740 if (key1->rec_type == key2->rec_type) { 2741 MAKE_SEPARATOR(key1, key2, dest, key); 2742 /* 2743 * Don't bother creating a separator for 2744 * create_tid, which also conveniently avoids 2745 * having to handle the create_tid == 0 2746 * (infinity) case. Just leave create_tid 2747 * set to key2. 2748 * 2749 * Worst case, dest matches key2 exactly, 2750 * which is acceptable. 2751 */ 2752 } 2753 } 2754 } 2755 } 2756 2757 #undef MAKE_SEPARATOR 2758 2759 /* 2760 * Return whether a generic internal or leaf node is full 2761 */ 2762 static int 2763 btree_node_is_full(hammer_node_ondisk_t node) 2764 { 2765 switch(node->type) { 2766 case HAMMER_BTREE_TYPE_INTERNAL: 2767 if (node->count == HAMMER_BTREE_INT_ELMS) 2768 return(1); 2769 break; 2770 case HAMMER_BTREE_TYPE_LEAF: 2771 if (node->count == HAMMER_BTREE_LEAF_ELMS) 2772 return(1); 2773 break; 2774 default: 2775 panic("illegal btree subtype"); 2776 } 2777 return(0); 2778 } 2779 2780 #if 0 2781 static int 2782 btree_max_elements(u_int8_t type) 2783 { 2784 if (type == HAMMER_BTREE_TYPE_LEAF) 2785 return(HAMMER_BTREE_LEAF_ELMS); 2786 if (type == HAMMER_BTREE_TYPE_INTERNAL) 2787 return(HAMMER_BTREE_INT_ELMS); 2788 panic("btree_max_elements: bad type %d\n", type); 2789 } 2790 #endif 2791 2792 void 2793 hammer_print_btree_node(hammer_node_ondisk_t ondisk) 2794 { 2795 hammer_btree_elm_t elm; 2796 int i; 2797 2798 kprintf("node %p count=%d parent=%016llx type=%c\n", 2799 ondisk, ondisk->count, ondisk->parent, ondisk->type); 2800 2801 /* 2802 * Dump both boundary elements if an internal node 2803 */ 2804 if (ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2805 for (i = 0; i <= ondisk->count; ++i) { 2806 elm = &ondisk->elms[i]; 2807 hammer_print_btree_elm(elm, ondisk->type, i); 2808 } 2809 } else { 2810 for (i = 0; i < ondisk->count; ++i) { 2811 elm = &ondisk->elms[i]; 2812 hammer_print_btree_elm(elm, ondisk->type, i); 2813 } 2814 } 2815 } 2816 2817 void 2818 hammer_print_btree_elm(hammer_btree_elm_t elm, u_int8_t type, int i) 2819 { 2820 kprintf(" %2d", i); 2821 kprintf("\tobj_id = %016llx\n", elm->base.obj_id); 2822 kprintf("\tkey = %016llx\n", elm->base.key); 2823 kprintf("\tcreate_tid = %016llx\n", elm->base.create_tid); 2824 kprintf("\tdelete_tid = %016llx\n", elm->base.delete_tid); 2825 kprintf("\trec_type = %04x\n", elm->base.rec_type); 2826 kprintf("\tobj_type = %02x\n", elm->base.obj_type); 2827 kprintf("\tbtype = %02x (%c)\n", 2828 elm->base.btype, 2829 (elm->base.btype ? elm->base.btype : '?')); 2830 kprintf("\tlocalization = %02x\n", elm->base.localization); 2831 2832 switch(type) { 2833 case HAMMER_BTREE_TYPE_INTERNAL: 2834 kprintf("\tsubtree_off = %016llx\n", 2835 elm->internal.subtree_offset); 2836 break; 2837 case HAMMER_BTREE_TYPE_RECORD: 2838 kprintf("\tdata_offset = %016llx\n", elm->leaf.data_offset); 2839 kprintf("\tdata_len = %08x\n", elm->leaf.data_len); 2840 kprintf("\tdata_crc = %08x\n", elm->leaf.data_crc); 2841 break; 2842 } 2843 } 2844