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 if (hammer_debug_debug & 0x0001) 714 Debugger("CRC FAILED: DATA"); 715 if (cursor->trans->flags & HAMMER_TRANSF_CRCDOM) 716 error = EDOM; /* less critical (mirroring) */ 717 else 718 error = EIO; /* critical */ 719 } 720 return(error); 721 } 722 723 724 /* 725 * Insert a leaf element into the B-Tree at the current cursor position. 726 * The cursor is positioned such that the element at and beyond the cursor 727 * are shifted to make room for the new record. 728 * 729 * The caller must call hammer_btree_lookup() with the HAMMER_CURSOR_INSERT 730 * flag set and that call must return ENOENT before this function can be 731 * called. 732 * 733 * The caller may depend on the cursor's exclusive lock after return to 734 * interlock frontend visibility (see HAMMER_RECF_CONVERT_DELETE). 735 * 736 * ENOSPC is returned if there is no room to insert a new record. 737 */ 738 int 739 hammer_btree_insert(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm, 740 int *doprop) 741 { 742 hammer_node_ondisk_t node; 743 int i; 744 int error; 745 746 *doprop = 0; 747 if ((error = hammer_cursor_upgrade_node(cursor)) != 0) 748 return(error); 749 ++hammer_stats_btree_inserts; 750 751 /* 752 * Insert the element at the leaf node and update the count in the 753 * parent. It is possible for parent to be NULL, indicating that 754 * the filesystem's ROOT B-Tree node is a leaf itself, which is 755 * possible. The root inode can never be deleted so the leaf should 756 * never be empty. 757 * 758 * Remember that the right-hand boundary is not included in the 759 * count. 760 */ 761 hammer_modify_node_all(cursor->trans, cursor->node); 762 node = cursor->node->ondisk; 763 i = cursor->index; 764 KKASSERT(elm->base.btype != 0); 765 KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF); 766 KKASSERT(node->count < HAMMER_BTREE_LEAF_ELMS); 767 if (i != node->count) { 768 bcopy(&node->elms[i], &node->elms[i+1], 769 (node->count - i) * sizeof(*elm)); 770 } 771 node->elms[i].leaf = *elm; 772 ++node->count; 773 hammer_cursor_inserted_element(cursor->node, i); 774 775 /* 776 * Update the leaf node's aggregate mirror_tid for mirroring 777 * support. 778 */ 779 if (node->mirror_tid < elm->base.delete_tid) { 780 node->mirror_tid = elm->base.delete_tid; 781 *doprop = 1; 782 } 783 if (node->mirror_tid < elm->base.create_tid) { 784 node->mirror_tid = elm->base.create_tid; 785 *doprop = 1; 786 } 787 hammer_modify_node_done(cursor->node); 788 789 /* 790 * Debugging sanity checks. 791 */ 792 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->base) <= 0); 793 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->base) > 0); 794 if (i) { 795 KKASSERT(hammer_btree_cmp(&node->elms[i-1].leaf.base, &elm->base) < 0); 796 } 797 if (i != node->count - 1) 798 KKASSERT(hammer_btree_cmp(&node->elms[i+1].leaf.base, &elm->base) > 0); 799 800 return(0); 801 } 802 803 /* 804 * Delete a record from the B-Tree at the current cursor position. 805 * The cursor is positioned such that the current element is the one 806 * to be deleted. 807 * 808 * On return the cursor will be positioned after the deleted element and 809 * MAY point to an internal node. It will be suitable for the continuation 810 * of an iteration but not for an insertion or deletion. 811 * 812 * Deletions will attempt to partially rebalance the B-Tree in an upward 813 * direction, but will terminate rather then deadlock. Empty internal nodes 814 * are never allowed by a deletion which deadlocks may end up giving us an 815 * empty leaf. The pruner will clean up and rebalance the tree. 816 * 817 * This function can return EDEADLK, requiring the caller to retry the 818 * operation after clearing the deadlock. 819 */ 820 int 821 hammer_btree_delete(hammer_cursor_t cursor) 822 { 823 hammer_node_ondisk_t ondisk; 824 hammer_node_t node; 825 hammer_node_t parent; 826 int error; 827 int i; 828 829 KKASSERT (cursor->trans->sync_lock_refs > 0); 830 if ((error = hammer_cursor_upgrade(cursor)) != 0) 831 return(error); 832 ++hammer_stats_btree_deletes; 833 834 /* 835 * Delete the element from the leaf node. 836 * 837 * Remember that leaf nodes do not have boundaries. 838 */ 839 node = cursor->node; 840 ondisk = node->ondisk; 841 i = cursor->index; 842 843 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_LEAF); 844 KKASSERT(i >= 0 && i < ondisk->count); 845 hammer_modify_node_all(cursor->trans, node); 846 if (i + 1 != ondisk->count) { 847 bcopy(&ondisk->elms[i+1], &ondisk->elms[i], 848 (ondisk->count - i - 1) * sizeof(ondisk->elms[0])); 849 } 850 --ondisk->count; 851 hammer_modify_node_done(node); 852 hammer_cursor_deleted_element(node, i); 853 854 /* 855 * Validate local parent 856 */ 857 if (ondisk->parent) { 858 parent = cursor->parent; 859 860 KKASSERT(parent != NULL); 861 KKASSERT(parent->node_offset == ondisk->parent); 862 } 863 864 /* 865 * If the leaf becomes empty it must be detached from the parent, 866 * potentially recursing through to the filesystem root. 867 * 868 * This may reposition the cursor at one of the parent's of the 869 * current node. 870 * 871 * Ignore deadlock errors, that simply means that btree_remove 872 * was unable to recurse and had to leave us with an empty leaf. 873 */ 874 KKASSERT(cursor->index <= ondisk->count); 875 if (ondisk->count == 0) { 876 error = btree_remove(cursor); 877 if (error == EDEADLK) 878 error = 0; 879 } else { 880 error = 0; 881 } 882 KKASSERT(cursor->parent == NULL || 883 cursor->parent_index < cursor->parent->ondisk->count); 884 return(error); 885 } 886 887 /* 888 * PRIMAY B-TREE SEARCH SUPPORT PROCEDURE 889 * 890 * Search the filesystem B-Tree for cursor->key_beg, return the matching node. 891 * 892 * The search can begin ANYWHERE in the B-Tree. As a first step the search 893 * iterates up the tree as necessary to properly position itself prior to 894 * actually doing the sarch. 895 * 896 * INSERTIONS: The search will split full nodes and leaves on its way down 897 * and guarentee that the leaf it ends up on is not full. If we run out 898 * of space the search continues to the leaf (to position the cursor for 899 * the spike), but ENOSPC is returned. 900 * 901 * The search is only guarenteed to end up on a leaf if an error code of 0 902 * is returned, or if inserting and an error code of ENOENT is returned. 903 * Otherwise it can stop at an internal node. On success a search returns 904 * a leaf node. 905 * 906 * COMPLEXITY WARNING! This is the core B-Tree search code for the entire 907 * filesystem, and it is not simple code. Please note the following facts: 908 * 909 * - Internal node recursions have a boundary on the left AND right. The 910 * right boundary is non-inclusive. The create_tid is a generic part 911 * of the key for internal nodes. 912 * 913 * - Leaf nodes contain terminal elements only now. 914 * 915 * - Filesystem lookups typically set HAMMER_CURSOR_ASOF, indicating a 916 * historical search. ASOF and INSERT are mutually exclusive. When 917 * doing an as-of lookup btree_search() checks for a right-edge boundary 918 * case. If while recursing down the left-edge differs from the key 919 * by ONLY its create_tid, HAMMER_CURSOR_CREATE_CHECK is set along 920 * with cursor->create_check. This is used by btree_lookup() to iterate. 921 * The iteration backwards because as-of searches can wind up going 922 * down the wrong branch of the B-Tree. 923 */ 924 static 925 int 926 btree_search(hammer_cursor_t cursor, int flags) 927 { 928 hammer_node_ondisk_t node; 929 hammer_btree_elm_t elm; 930 int error; 931 int enospc = 0; 932 int i; 933 int r; 934 int s; 935 936 flags |= cursor->flags; 937 ++hammer_stats_btree_searches; 938 939 if (hammer_debug_btree) { 940 kprintf("SEARCH %016llx[%d] %016llx %02x key=%016llx cre=%016llx lo=%02x (td = %p)\n", 941 cursor->node->node_offset, 942 cursor->index, 943 cursor->key_beg.obj_id, 944 cursor->key_beg.rec_type, 945 cursor->key_beg.key, 946 cursor->key_beg.create_tid, 947 cursor->key_beg.localization, 948 curthread 949 ); 950 if (cursor->parent) 951 kprintf("SEARCHP %016llx[%d] (%016llx/%016llx %016llx/%016llx) (%p/%p %p/%p)\n", 952 cursor->parent->node_offset, cursor->parent_index, 953 cursor->left_bound->obj_id, 954 cursor->parent->ondisk->elms[cursor->parent_index].internal.base.obj_id, 955 cursor->right_bound->obj_id, 956 cursor->parent->ondisk->elms[cursor->parent_index+1].internal.base.obj_id, 957 cursor->left_bound, 958 &cursor->parent->ondisk->elms[cursor->parent_index], 959 cursor->right_bound, 960 &cursor->parent->ondisk->elms[cursor->parent_index+1] 961 ); 962 } 963 964 /* 965 * Move our cursor up the tree until we find a node whos range covers 966 * the key we are trying to locate. 967 * 968 * The left bound is inclusive, the right bound is non-inclusive. 969 * It is ok to cursor up too far. 970 */ 971 for (;;) { 972 r = hammer_btree_cmp(&cursor->key_beg, cursor->left_bound); 973 s = hammer_btree_cmp(&cursor->key_beg, cursor->right_bound); 974 if (r >= 0 && s < 0) 975 break; 976 KKASSERT(cursor->parent); 977 ++hammer_stats_btree_iterations; 978 error = hammer_cursor_up(cursor); 979 if (error) 980 goto done; 981 } 982 983 /* 984 * The delete-checks below are based on node, not parent. Set the 985 * initial delete-check based on the parent. 986 */ 987 if (r == 1) { 988 KKASSERT(cursor->left_bound->create_tid != 1); 989 cursor->create_check = cursor->left_bound->create_tid - 1; 990 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK; 991 } 992 993 /* 994 * We better have ended up with a node somewhere. 995 */ 996 KKASSERT(cursor->node != NULL); 997 998 /* 999 * If we are inserting we can't start at a full node if the parent 1000 * is also full (because there is no way to split the node), 1001 * continue running up the tree until the requirement is satisfied 1002 * or we hit the root of the filesystem. 1003 * 1004 * (If inserting we aren't doing an as-of search so we don't have 1005 * to worry about create_check). 1006 */ 1007 while ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) { 1008 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 1009 if (btree_node_is_full(cursor->node->ondisk) == 0) 1010 break; 1011 } else { 1012 if (btree_node_is_full(cursor->node->ondisk) ==0) 1013 break; 1014 } 1015 if (cursor->node->ondisk->parent == 0 || 1016 cursor->parent->ondisk->count != HAMMER_BTREE_INT_ELMS) { 1017 break; 1018 } 1019 ++hammer_stats_btree_iterations; 1020 error = hammer_cursor_up(cursor); 1021 /* node may have become stale */ 1022 if (error) 1023 goto done; 1024 } 1025 1026 /* 1027 * Push down through internal nodes to locate the requested key. 1028 */ 1029 node = cursor->node->ondisk; 1030 while (node->type == HAMMER_BTREE_TYPE_INTERNAL) { 1031 /* 1032 * Scan the node to find the subtree index to push down into. 1033 * We go one-past, then back-up. 1034 * 1035 * We must proactively remove deleted elements which may 1036 * have been left over from a deadlocked btree_remove(). 1037 * 1038 * The left and right boundaries are included in the loop 1039 * in order to detect edge cases. 1040 * 1041 * If the separator only differs by create_tid (r == 1) 1042 * and we are doing an as-of search, we may end up going 1043 * down a branch to the left of the one containing the 1044 * desired key. This requires numerous special cases. 1045 */ 1046 ++hammer_stats_btree_iterations; 1047 if (hammer_debug_btree) { 1048 kprintf("SEARCH-I %016llx count=%d\n", 1049 cursor->node->node_offset, 1050 node->count); 1051 } 1052 1053 /* 1054 * Try to shortcut the search before dropping into the 1055 * linear loop. Locate the first node where r <= 1. 1056 */ 1057 i = hammer_btree_search_node(&cursor->key_beg, node); 1058 while (i <= node->count) { 1059 ++hammer_stats_btree_elements; 1060 elm = &node->elms[i]; 1061 r = hammer_btree_cmp(&cursor->key_beg, &elm->base); 1062 if (hammer_debug_btree > 2) { 1063 kprintf(" IELM %p %d r=%d\n", 1064 &node->elms[i], i, r); 1065 } 1066 if (r < 0) 1067 break; 1068 if (r == 1) { 1069 KKASSERT(elm->base.create_tid != 1); 1070 cursor->create_check = elm->base.create_tid - 1; 1071 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK; 1072 } 1073 ++i; 1074 } 1075 if (hammer_debug_btree) { 1076 kprintf("SEARCH-I preI=%d/%d r=%d\n", 1077 i, node->count, r); 1078 } 1079 1080 /* 1081 * These cases occur when the parent's idea of the boundary 1082 * is wider then the child's idea of the boundary, and 1083 * require special handling. If not inserting we can 1084 * terminate the search early for these cases but the 1085 * child's boundaries cannot be unconditionally modified. 1086 */ 1087 if (i == 0) { 1088 /* 1089 * If i == 0 the search terminated to the LEFT of the 1090 * left_boundary but to the RIGHT of the parent's left 1091 * boundary. 1092 */ 1093 u_int8_t save; 1094 1095 elm = &node->elms[0]; 1096 1097 /* 1098 * If we aren't inserting we can stop here. 1099 */ 1100 if ((flags & (HAMMER_CURSOR_INSERT | 1101 HAMMER_CURSOR_PRUNING)) == 0) { 1102 cursor->index = 0; 1103 return(ENOENT); 1104 } 1105 1106 /* 1107 * Correct a left-hand boundary mismatch. 1108 * 1109 * We can only do this if we can upgrade the lock, 1110 * and synchronized as a background cursor (i.e. 1111 * inserting or pruning). 1112 * 1113 * WARNING: We can only do this if inserting, i.e. 1114 * we are running on the backend. 1115 */ 1116 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1117 return(error); 1118 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND); 1119 hammer_modify_node_field(cursor->trans, cursor->node, 1120 elms[0]); 1121 save = node->elms[0].base.btype; 1122 node->elms[0].base = *cursor->left_bound; 1123 node->elms[0].base.btype = save; 1124 hammer_modify_node_done(cursor->node); 1125 } else if (i == node->count + 1) { 1126 /* 1127 * If i == node->count + 1 the search terminated to 1128 * the RIGHT of the right boundary but to the LEFT 1129 * of the parent's right boundary. If we aren't 1130 * inserting we can stop here. 1131 * 1132 * Note that the last element in this case is 1133 * elms[i-2] prior to adjustments to 'i'. 1134 */ 1135 --i; 1136 if ((flags & (HAMMER_CURSOR_INSERT | 1137 HAMMER_CURSOR_PRUNING)) == 0) { 1138 cursor->index = i; 1139 return (ENOENT); 1140 } 1141 1142 /* 1143 * Correct a right-hand boundary mismatch. 1144 * (actual push-down record is i-2 prior to 1145 * adjustments to i). 1146 * 1147 * We can only do this if we can upgrade the lock, 1148 * and synchronized as a background cursor (i.e. 1149 * inserting or pruning). 1150 * 1151 * WARNING: We can only do this if inserting, i.e. 1152 * we are running on the backend. 1153 */ 1154 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1155 return(error); 1156 elm = &node->elms[i]; 1157 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND); 1158 hammer_modify_node(cursor->trans, cursor->node, 1159 &elm->base, sizeof(elm->base)); 1160 elm->base = *cursor->right_bound; 1161 hammer_modify_node_done(cursor->node); 1162 --i; 1163 } else { 1164 /* 1165 * The push-down index is now i - 1. If we had 1166 * terminated on the right boundary this will point 1167 * us at the last element. 1168 */ 1169 --i; 1170 } 1171 cursor->index = i; 1172 elm = &node->elms[i]; 1173 1174 if (hammer_debug_btree) { 1175 kprintf("RESULT-I %016llx[%d] %016llx %02x " 1176 "key=%016llx cre=%016llx lo=%02x\n", 1177 cursor->node->node_offset, 1178 i, 1179 elm->internal.base.obj_id, 1180 elm->internal.base.rec_type, 1181 elm->internal.base.key, 1182 elm->internal.base.create_tid, 1183 elm->internal.base.localization 1184 ); 1185 } 1186 1187 /* 1188 * We better have a valid subtree offset. 1189 */ 1190 KKASSERT(elm->internal.subtree_offset != 0); 1191 1192 /* 1193 * Handle insertion and deletion requirements. 1194 * 1195 * If inserting split full nodes. The split code will 1196 * adjust cursor->node and cursor->index if the current 1197 * index winds up in the new node. 1198 * 1199 * If inserting and a left or right edge case was detected, 1200 * we cannot correct the left or right boundary and must 1201 * prepend and append an empty leaf node in order to make 1202 * the boundary correction. 1203 * 1204 * If we run out of space we set enospc and continue on 1205 * to a leaf to provide the spike code with a good point 1206 * of entry. 1207 */ 1208 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) { 1209 if (btree_node_is_full(node)) { 1210 error = btree_split_internal(cursor); 1211 if (error) { 1212 if (error != ENOSPC) 1213 goto done; 1214 enospc = 1; 1215 } 1216 /* 1217 * reload stale pointers 1218 */ 1219 i = cursor->index; 1220 node = cursor->node->ondisk; 1221 } 1222 } 1223 1224 /* 1225 * Push down (push into new node, existing node becomes 1226 * the parent) and continue the search. 1227 */ 1228 error = hammer_cursor_down(cursor); 1229 /* node may have become stale */ 1230 if (error) 1231 goto done; 1232 node = cursor->node->ondisk; 1233 } 1234 1235 /* 1236 * We are at a leaf, do a linear search of the key array. 1237 * 1238 * On success the index is set to the matching element and 0 1239 * is returned. 1240 * 1241 * On failure the index is set to the insertion point and ENOENT 1242 * is returned. 1243 * 1244 * Boundaries are not stored in leaf nodes, so the index can wind 1245 * up to the left of element 0 (index == 0) or past the end of 1246 * the array (index == node->count). It is also possible that the 1247 * leaf might be empty. 1248 */ 1249 ++hammer_stats_btree_iterations; 1250 KKASSERT (node->type == HAMMER_BTREE_TYPE_LEAF); 1251 KKASSERT(node->count <= HAMMER_BTREE_LEAF_ELMS); 1252 if (hammer_debug_btree) { 1253 kprintf("SEARCH-L %016llx count=%d\n", 1254 cursor->node->node_offset, 1255 node->count); 1256 } 1257 1258 /* 1259 * Try to shortcut the search before dropping into the 1260 * linear loop. Locate the first node where r <= 1. 1261 */ 1262 i = hammer_btree_search_node(&cursor->key_beg, node); 1263 while (i < node->count) { 1264 ++hammer_stats_btree_elements; 1265 elm = &node->elms[i]; 1266 1267 r = hammer_btree_cmp(&cursor->key_beg, &elm->leaf.base); 1268 1269 if (hammer_debug_btree > 1) 1270 kprintf(" ELM %p %d r=%d\n", &node->elms[i], i, r); 1271 1272 /* 1273 * We are at a record element. Stop if we've flipped past 1274 * key_beg, not counting the create_tid test. Allow the 1275 * r == 1 case (key_beg > element but differs only by its 1276 * create_tid) to fall through to the AS-OF check. 1277 */ 1278 KKASSERT (elm->leaf.base.btype == HAMMER_BTREE_TYPE_RECORD); 1279 1280 if (r < 0) 1281 goto failed; 1282 if (r > 1) { 1283 ++i; 1284 continue; 1285 } 1286 1287 /* 1288 * Check our as-of timestamp against the element. 1289 */ 1290 if (flags & HAMMER_CURSOR_ASOF) { 1291 if (hammer_btree_chkts(cursor->asof, 1292 &node->elms[i].base) != 0) { 1293 ++i; 1294 continue; 1295 } 1296 /* success */ 1297 } else { 1298 if (r > 0) { /* can only be +1 */ 1299 ++i; 1300 continue; 1301 } 1302 /* success */ 1303 } 1304 cursor->index = i; 1305 error = 0; 1306 if (hammer_debug_btree) { 1307 kprintf("RESULT-L %016llx[%d] (SUCCESS)\n", 1308 cursor->node->node_offset, i); 1309 } 1310 goto done; 1311 } 1312 1313 /* 1314 * The search of the leaf node failed. i is the insertion point. 1315 */ 1316 failed: 1317 if (hammer_debug_btree) { 1318 kprintf("RESULT-L %016llx[%d] (FAILED)\n", 1319 cursor->node->node_offset, i); 1320 } 1321 1322 /* 1323 * No exact match was found, i is now at the insertion point. 1324 * 1325 * If inserting split a full leaf before returning. This 1326 * may have the side effect of adjusting cursor->node and 1327 * cursor->index. 1328 */ 1329 cursor->index = i; 1330 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0 && 1331 btree_node_is_full(node)) { 1332 error = btree_split_leaf(cursor); 1333 if (error) { 1334 if (error != ENOSPC) 1335 goto done; 1336 enospc = 1; 1337 } 1338 /* 1339 * reload stale pointers 1340 */ 1341 /* NOT USED 1342 i = cursor->index; 1343 node = &cursor->node->internal; 1344 */ 1345 } 1346 1347 /* 1348 * We reached a leaf but did not find the key we were looking for. 1349 * If this is an insert we will be properly positioned for an insert 1350 * (ENOENT) or spike (ENOSPC) operation. 1351 */ 1352 error = enospc ? ENOSPC : ENOENT; 1353 done: 1354 return(error); 1355 } 1356 1357 /* 1358 * Heuristical search for the first element whos comparison is <= 1. May 1359 * return an index whos compare result is > 1 but may only return an index 1360 * whos compare result is <= 1 if it is the first element with that result. 1361 */ 1362 int 1363 hammer_btree_search_node(hammer_base_elm_t elm, hammer_node_ondisk_t node) 1364 { 1365 int b; 1366 int s; 1367 int i; 1368 int r; 1369 1370 /* 1371 * Don't bother if the node does not have very many elements 1372 */ 1373 b = 0; 1374 s = node->count; 1375 while (s - b > 4) { 1376 i = b + (s - b) / 2; 1377 ++hammer_stats_btree_elements; 1378 r = hammer_btree_cmp(elm, &node->elms[i].leaf.base); 1379 if (r <= 1) { 1380 s = i; 1381 } else { 1382 b = i; 1383 } 1384 } 1385 return(b); 1386 } 1387 1388 1389 /************************************************************************ 1390 * SPLITTING AND MERGING * 1391 ************************************************************************ 1392 * 1393 * These routines do all the dirty work required to split and merge nodes. 1394 */ 1395 1396 /* 1397 * Split an internal node into two nodes and move the separator at the split 1398 * point to the parent. 1399 * 1400 * (cursor->node, cursor->index) indicates the element the caller intends 1401 * to push into. We will adjust node and index if that element winds 1402 * up in the split node. 1403 * 1404 * If we are at the root of the filesystem a new root must be created with 1405 * two elements, one pointing to the original root and one pointing to the 1406 * newly allocated split node. 1407 */ 1408 static 1409 int 1410 btree_split_internal(hammer_cursor_t cursor) 1411 { 1412 hammer_node_ondisk_t ondisk; 1413 hammer_node_t node; 1414 hammer_node_t parent; 1415 hammer_node_t new_node; 1416 hammer_btree_elm_t elm; 1417 hammer_btree_elm_t parent_elm; 1418 struct hammer_node_lock lockroot; 1419 hammer_mount_t hmp = cursor->trans->hmp; 1420 int parent_index; 1421 int made_root; 1422 int split; 1423 int error; 1424 int i; 1425 const int esize = sizeof(*elm); 1426 1427 hammer_node_lock_init(&lockroot, cursor->node); 1428 error = hammer_btree_lock_children(cursor, 1, &lockroot); 1429 if (error) 1430 goto done; 1431 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1432 goto done; 1433 ++hammer_stats_btree_splits; 1434 1435 /* 1436 * We are splitting but elms[split] will be promoted to the parent, 1437 * leaving the right hand node with one less element. If the 1438 * insertion point will be on the left-hand side adjust the split 1439 * point to give the right hand side one additional node. 1440 */ 1441 node = cursor->node; 1442 ondisk = node->ondisk; 1443 split = (ondisk->count + 1) / 2; 1444 if (cursor->index <= split) 1445 --split; 1446 1447 /* 1448 * If we are at the root of the filesystem, create a new root node 1449 * with 1 element and split normally. Avoid making major 1450 * modifications until we know the whole operation will work. 1451 */ 1452 if (ondisk->parent == 0) { 1453 parent = hammer_alloc_btree(cursor->trans, &error); 1454 if (parent == NULL) 1455 goto done; 1456 hammer_lock_ex(&parent->lock); 1457 hammer_modify_node_noundo(cursor->trans, parent); 1458 ondisk = parent->ondisk; 1459 ondisk->count = 1; 1460 ondisk->parent = 0; 1461 ondisk->mirror_tid = node->ondisk->mirror_tid; 1462 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1463 ondisk->elms[0].base = hmp->root_btree_beg; 1464 ondisk->elms[0].base.btype = node->ondisk->type; 1465 ondisk->elms[0].internal.subtree_offset = node->node_offset; 1466 ondisk->elms[1].base = hmp->root_btree_end; 1467 hammer_modify_node_done(parent); 1468 /* ondisk->elms[1].base.btype - not used */ 1469 made_root = 1; 1470 parent_index = 0; /* index of current node in parent */ 1471 } else { 1472 made_root = 0; 1473 parent = cursor->parent; 1474 parent_index = cursor->parent_index; 1475 } 1476 1477 /* 1478 * Split node into new_node at the split point. 1479 * 1480 * B O O O P N N B <-- P = node->elms[split] 1481 * 0 1 2 3 4 5 6 <-- subtree indices 1482 * 1483 * x x P x x 1484 * s S S s 1485 * / \ 1486 * B O O O B B N N B <--- inner boundary points are 'P' 1487 * 0 1 2 3 4 5 6 1488 * 1489 */ 1490 new_node = hammer_alloc_btree(cursor->trans, &error); 1491 if (new_node == NULL) { 1492 if (made_root) { 1493 hammer_unlock(&parent->lock); 1494 hammer_delete_node(cursor->trans, parent); 1495 hammer_rel_node(parent); 1496 } 1497 goto done; 1498 } 1499 hammer_lock_ex(&new_node->lock); 1500 1501 /* 1502 * Create the new node. P becomes the left-hand boundary in the 1503 * new node. Copy the right-hand boundary as well. 1504 * 1505 * elm is the new separator. 1506 */ 1507 hammer_modify_node_noundo(cursor->trans, new_node); 1508 hammer_modify_node_all(cursor->trans, node); 1509 ondisk = node->ondisk; 1510 elm = &ondisk->elms[split]; 1511 bcopy(elm, &new_node->ondisk->elms[0], 1512 (ondisk->count - split + 1) * esize); 1513 new_node->ondisk->count = ondisk->count - split; 1514 new_node->ondisk->parent = parent->node_offset; 1515 new_node->ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1516 new_node->ondisk->mirror_tid = ondisk->mirror_tid; 1517 KKASSERT(ondisk->type == new_node->ondisk->type); 1518 hammer_cursor_split_node(node, new_node, split); 1519 1520 /* 1521 * Cleanup the original node. Elm (P) becomes the new boundary, 1522 * its subtree_offset was moved to the new node. If we had created 1523 * a new root its parent pointer may have changed. 1524 */ 1525 elm->internal.subtree_offset = 0; 1526 ondisk->count = split; 1527 1528 /* 1529 * Insert the separator into the parent, fixup the parent's 1530 * reference to the original node, and reference the new node. 1531 * The separator is P. 1532 * 1533 * Remember that base.count does not include the right-hand boundary. 1534 */ 1535 hammer_modify_node_all(cursor->trans, parent); 1536 ondisk = parent->ondisk; 1537 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS); 1538 parent_elm = &ondisk->elms[parent_index+1]; 1539 bcopy(parent_elm, parent_elm + 1, 1540 (ondisk->count - parent_index) * esize); 1541 parent_elm->internal.base = elm->base; /* separator P */ 1542 parent_elm->internal.base.btype = new_node->ondisk->type; 1543 parent_elm->internal.subtree_offset = new_node->node_offset; 1544 parent_elm->internal.mirror_tid = new_node->ondisk->mirror_tid; 1545 ++ondisk->count; 1546 hammer_modify_node_done(parent); 1547 hammer_cursor_inserted_element(parent, parent_index + 1); 1548 1549 /* 1550 * The children of new_node need their parent pointer set to new_node. 1551 * The children have already been locked by 1552 * hammer_btree_lock_children(). 1553 */ 1554 for (i = 0; i < new_node->ondisk->count; ++i) { 1555 elm = &new_node->ondisk->elms[i]; 1556 error = btree_set_parent(cursor->trans, new_node, elm); 1557 if (error) { 1558 panic("btree_split_internal: btree-fixup problem"); 1559 } 1560 } 1561 hammer_modify_node_done(new_node); 1562 1563 /* 1564 * The filesystem's root B-Tree pointer may have to be updated. 1565 */ 1566 if (made_root) { 1567 hammer_volume_t volume; 1568 1569 volume = hammer_get_root_volume(hmp, &error); 1570 KKASSERT(error == 0); 1571 1572 hammer_modify_volume_field(cursor->trans, volume, 1573 vol0_btree_root); 1574 volume->ondisk->vol0_btree_root = parent->node_offset; 1575 hammer_modify_volume_done(volume); 1576 node->ondisk->parent = parent->node_offset; 1577 if (cursor->parent) { 1578 hammer_unlock(&cursor->parent->lock); 1579 hammer_rel_node(cursor->parent); 1580 } 1581 cursor->parent = parent; /* lock'd and ref'd */ 1582 hammer_rel_volume(volume, 0); 1583 } 1584 hammer_modify_node_done(node); 1585 1586 /* 1587 * Ok, now adjust the cursor depending on which element the original 1588 * index was pointing at. If we are >= the split point the push node 1589 * is now in the new node. 1590 * 1591 * NOTE: If we are at the split point itself we cannot stay with the 1592 * original node because the push index will point at the right-hand 1593 * boundary, which is illegal. 1594 * 1595 * NOTE: The cursor's parent or parent_index must be adjusted for 1596 * the case where a new parent (new root) was created, and the case 1597 * where the cursor is now pointing at the split node. 1598 */ 1599 if (cursor->index >= split) { 1600 cursor->parent_index = parent_index + 1; 1601 cursor->index -= split; 1602 hammer_unlock(&cursor->node->lock); 1603 hammer_rel_node(cursor->node); 1604 cursor->node = new_node; /* locked and ref'd */ 1605 } else { 1606 cursor->parent_index = parent_index; 1607 hammer_unlock(&new_node->lock); 1608 hammer_rel_node(new_node); 1609 } 1610 1611 /* 1612 * Fixup left and right bounds 1613 */ 1614 parent_elm = &parent->ondisk->elms[cursor->parent_index]; 1615 cursor->left_bound = &parent_elm[0].internal.base; 1616 cursor->right_bound = &parent_elm[1].internal.base; 1617 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1618 &cursor->node->ondisk->elms[0].internal.base) <= 0); 1619 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1620 &cursor->node->ondisk->elms[cursor->node->ondisk->count].internal.base) >= 0); 1621 1622 done: 1623 hammer_btree_unlock_children(cursor, &lockroot); 1624 hammer_cursor_downgrade(cursor); 1625 return (error); 1626 } 1627 1628 /* 1629 * Same as the above, but splits a full leaf node. 1630 * 1631 * This function 1632 */ 1633 static 1634 int 1635 btree_split_leaf(hammer_cursor_t cursor) 1636 { 1637 hammer_node_ondisk_t ondisk; 1638 hammer_node_t parent; 1639 hammer_node_t leaf; 1640 hammer_mount_t hmp; 1641 hammer_node_t new_leaf; 1642 hammer_btree_elm_t elm; 1643 hammer_btree_elm_t parent_elm; 1644 hammer_base_elm_t mid_boundary; 1645 int parent_index; 1646 int made_root; 1647 int split; 1648 int error; 1649 const size_t esize = sizeof(*elm); 1650 1651 if ((error = hammer_cursor_upgrade(cursor)) != 0) 1652 return(error); 1653 ++hammer_stats_btree_splits; 1654 1655 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1656 &cursor->node->ondisk->elms[0].leaf.base) <= 0); 1657 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1658 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0); 1659 1660 /* 1661 * Calculate the split point. If the insertion point will be on 1662 * the left-hand side adjust the split point to give the right 1663 * hand side one additional node. 1664 * 1665 * Spikes are made up of two leaf elements which cannot be 1666 * safely split. 1667 */ 1668 leaf = cursor->node; 1669 ondisk = leaf->ondisk; 1670 split = (ondisk->count + 1) / 2; 1671 if (cursor->index <= split) 1672 --split; 1673 error = 0; 1674 hmp = leaf->hmp; 1675 1676 elm = &ondisk->elms[split]; 1677 1678 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm[-1].leaf.base) <= 0); 1679 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->leaf.base) <= 0); 1680 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->leaf.base) > 0); 1681 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm[1].leaf.base) > 0); 1682 1683 /* 1684 * If we are at the root of the tree, create a new root node with 1685 * 1 element and split normally. Avoid making major modifications 1686 * until we know the whole operation will work. 1687 */ 1688 if (ondisk->parent == 0) { 1689 parent = hammer_alloc_btree(cursor->trans, &error); 1690 if (parent == NULL) 1691 goto done; 1692 hammer_lock_ex(&parent->lock); 1693 hammer_modify_node_noundo(cursor->trans, parent); 1694 ondisk = parent->ondisk; 1695 ondisk->count = 1; 1696 ondisk->parent = 0; 1697 ondisk->mirror_tid = leaf->ondisk->mirror_tid; 1698 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL; 1699 ondisk->elms[0].base = hmp->root_btree_beg; 1700 ondisk->elms[0].base.btype = leaf->ondisk->type; 1701 ondisk->elms[0].internal.subtree_offset = leaf->node_offset; 1702 ondisk->elms[1].base = hmp->root_btree_end; 1703 /* ondisk->elms[1].base.btype = not used */ 1704 hammer_modify_node_done(parent); 1705 made_root = 1; 1706 parent_index = 0; /* insertion point in parent */ 1707 } else { 1708 made_root = 0; 1709 parent = cursor->parent; 1710 parent_index = cursor->parent_index; 1711 } 1712 1713 /* 1714 * Split leaf into new_leaf at the split point. Select a separator 1715 * value in-between the two leafs but with a bent towards the right 1716 * leaf since comparisons use an 'elm >= separator' inequality. 1717 * 1718 * L L L L L L L L 1719 * 1720 * x x P x x 1721 * s S S s 1722 * / \ 1723 * L L L L L L L L 1724 */ 1725 new_leaf = hammer_alloc_btree(cursor->trans, &error); 1726 if (new_leaf == NULL) { 1727 if (made_root) { 1728 hammer_unlock(&parent->lock); 1729 hammer_delete_node(cursor->trans, parent); 1730 hammer_rel_node(parent); 1731 } 1732 goto done; 1733 } 1734 hammer_lock_ex(&new_leaf->lock); 1735 1736 /* 1737 * Create the new node and copy the leaf elements from the split 1738 * point on to the new node. 1739 */ 1740 hammer_modify_node_all(cursor->trans, leaf); 1741 hammer_modify_node_noundo(cursor->trans, new_leaf); 1742 ondisk = leaf->ondisk; 1743 elm = &ondisk->elms[split]; 1744 bcopy(elm, &new_leaf->ondisk->elms[0], (ondisk->count - split) * esize); 1745 new_leaf->ondisk->count = ondisk->count - split; 1746 new_leaf->ondisk->parent = parent->node_offset; 1747 new_leaf->ondisk->type = HAMMER_BTREE_TYPE_LEAF; 1748 new_leaf->ondisk->mirror_tid = ondisk->mirror_tid; 1749 KKASSERT(ondisk->type == new_leaf->ondisk->type); 1750 hammer_modify_node_done(new_leaf); 1751 hammer_cursor_split_node(leaf, new_leaf, split); 1752 1753 /* 1754 * Cleanup the original node. Because this is a leaf node and 1755 * leaf nodes do not have a right-hand boundary, there 1756 * aren't any special edge cases to clean up. We just fixup the 1757 * count. 1758 */ 1759 ondisk->count = split; 1760 1761 /* 1762 * Insert the separator into the parent, fixup the parent's 1763 * reference to the original node, and reference the new node. 1764 * The separator is P. 1765 * 1766 * Remember that base.count does not include the right-hand boundary. 1767 * We are copying parent_index+1 to parent_index+2, not +0 to +1. 1768 */ 1769 hammer_modify_node_all(cursor->trans, parent); 1770 ondisk = parent->ondisk; 1771 KKASSERT(split != 0); 1772 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS); 1773 parent_elm = &ondisk->elms[parent_index+1]; 1774 bcopy(parent_elm, parent_elm + 1, 1775 (ondisk->count - parent_index) * esize); 1776 1777 hammer_make_separator(&elm[-1].base, &elm[0].base, &parent_elm->base); 1778 parent_elm->internal.base.btype = new_leaf->ondisk->type; 1779 parent_elm->internal.subtree_offset = new_leaf->node_offset; 1780 parent_elm->internal.mirror_tid = new_leaf->ondisk->mirror_tid; 1781 mid_boundary = &parent_elm->base; 1782 ++ondisk->count; 1783 hammer_modify_node_done(parent); 1784 hammer_cursor_inserted_element(parent, parent_index + 1); 1785 1786 /* 1787 * The filesystem's root B-Tree pointer may have to be updated. 1788 */ 1789 if (made_root) { 1790 hammer_volume_t volume; 1791 1792 volume = hammer_get_root_volume(hmp, &error); 1793 KKASSERT(error == 0); 1794 1795 hammer_modify_volume_field(cursor->trans, volume, 1796 vol0_btree_root); 1797 volume->ondisk->vol0_btree_root = parent->node_offset; 1798 hammer_modify_volume_done(volume); 1799 leaf->ondisk->parent = parent->node_offset; 1800 if (cursor->parent) { 1801 hammer_unlock(&cursor->parent->lock); 1802 hammer_rel_node(cursor->parent); 1803 } 1804 cursor->parent = parent; /* lock'd and ref'd */ 1805 hammer_rel_volume(volume, 0); 1806 } 1807 hammer_modify_node_done(leaf); 1808 1809 /* 1810 * Ok, now adjust the cursor depending on which element the original 1811 * index was pointing at. If we are >= the split point the push node 1812 * is now in the new node. 1813 * 1814 * NOTE: If we are at the split point itself we need to select the 1815 * old or new node based on where key_beg's insertion point will be. 1816 * If we pick the wrong side the inserted element will wind up in 1817 * the wrong leaf node and outside that node's bounds. 1818 */ 1819 if (cursor->index > split || 1820 (cursor->index == split && 1821 hammer_btree_cmp(&cursor->key_beg, mid_boundary) >= 0)) { 1822 cursor->parent_index = parent_index + 1; 1823 cursor->index -= split; 1824 hammer_unlock(&cursor->node->lock); 1825 hammer_rel_node(cursor->node); 1826 cursor->node = new_leaf; 1827 } else { 1828 cursor->parent_index = parent_index; 1829 hammer_unlock(&new_leaf->lock); 1830 hammer_rel_node(new_leaf); 1831 } 1832 1833 /* 1834 * Fixup left and right bounds 1835 */ 1836 parent_elm = &parent->ondisk->elms[cursor->parent_index]; 1837 cursor->left_bound = &parent_elm[0].internal.base; 1838 cursor->right_bound = &parent_elm[1].internal.base; 1839 1840 /* 1841 * Assert that the bounds are correct. 1842 */ 1843 KKASSERT(hammer_btree_cmp(cursor->left_bound, 1844 &cursor->node->ondisk->elms[0].leaf.base) <= 0); 1845 KKASSERT(hammer_btree_cmp(cursor->right_bound, 1846 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0); 1847 KKASSERT(hammer_btree_cmp(cursor->left_bound, &cursor->key_beg) <= 0); 1848 KKASSERT(hammer_btree_cmp(cursor->right_bound, &cursor->key_beg) > 0); 1849 1850 done: 1851 hammer_cursor_downgrade(cursor); 1852 return (error); 1853 } 1854 1855 #if 0 1856 1857 /* 1858 * Recursively correct the right-hand boundary's create_tid to (tid) as 1859 * long as the rest of the key matches. We have to recurse upward in 1860 * the tree as well as down the left side of each parent's right node. 1861 * 1862 * Return EDEADLK if we were only partially successful, forcing the caller 1863 * to try again. The original cursor is not modified. This routine can 1864 * also fail with EDEADLK if it is forced to throw away a portion of its 1865 * record history. 1866 * 1867 * The caller must pass a downgraded cursor to us (otherwise we can't dup it). 1868 */ 1869 struct hammer_rhb { 1870 TAILQ_ENTRY(hammer_rhb) entry; 1871 hammer_node_t node; 1872 int index; 1873 }; 1874 1875 TAILQ_HEAD(hammer_rhb_list, hammer_rhb); 1876 1877 int 1878 hammer_btree_correct_rhb(hammer_cursor_t cursor, hammer_tid_t tid) 1879 { 1880 struct hammer_mount *hmp; 1881 struct hammer_rhb_list rhb_list; 1882 hammer_base_elm_t elm; 1883 hammer_node_t orig_node; 1884 struct hammer_rhb *rhb; 1885 int orig_index; 1886 int error; 1887 1888 TAILQ_INIT(&rhb_list); 1889 hmp = cursor->trans->hmp; 1890 1891 /* 1892 * Save our position so we can restore it on return. This also 1893 * gives us a stable 'elm'. 1894 */ 1895 orig_node = cursor->node; 1896 hammer_ref_node(orig_node); 1897 hammer_lock_sh(&orig_node->lock); 1898 orig_index = cursor->index; 1899 elm = &orig_node->ondisk->elms[orig_index].base; 1900 1901 /* 1902 * Now build a list of parents going up, allocating a rhb 1903 * structure for each one. 1904 */ 1905 while (cursor->parent) { 1906 /* 1907 * Stop if we no longer have any right-bounds to fix up 1908 */ 1909 if (elm->obj_id != cursor->right_bound->obj_id || 1910 elm->rec_type != cursor->right_bound->rec_type || 1911 elm->key != cursor->right_bound->key) { 1912 break; 1913 } 1914 1915 /* 1916 * Stop if the right-hand bound's create_tid does not 1917 * need to be corrected. 1918 */ 1919 if (cursor->right_bound->create_tid >= tid) 1920 break; 1921 1922 rhb = kmalloc(sizeof(*rhb), hmp->m_misc, M_WAITOK|M_ZERO); 1923 rhb->node = cursor->parent; 1924 rhb->index = cursor->parent_index; 1925 hammer_ref_node(rhb->node); 1926 hammer_lock_sh(&rhb->node->lock); 1927 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry); 1928 1929 hammer_cursor_up(cursor); 1930 } 1931 1932 /* 1933 * now safely adjust the right hand bound for each rhb. This may 1934 * also require taking the right side of the tree and iterating down 1935 * ITS left side. 1936 */ 1937 error = 0; 1938 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 1939 error = hammer_cursor_seek(cursor, rhb->node, rhb->index); 1940 if (error) 1941 break; 1942 TAILQ_REMOVE(&rhb_list, rhb, entry); 1943 hammer_unlock(&rhb->node->lock); 1944 hammer_rel_node(rhb->node); 1945 kfree(rhb, hmp->m_misc); 1946 1947 switch (cursor->node->ondisk->type) { 1948 case HAMMER_BTREE_TYPE_INTERNAL: 1949 /* 1950 * Right-boundary for parent at internal node 1951 * is one element to the right of the element whos 1952 * right boundary needs adjusting. We must then 1953 * traverse down the left side correcting any left 1954 * bounds (which may now be too far to the left). 1955 */ 1956 ++cursor->index; 1957 error = hammer_btree_correct_lhb(cursor, tid); 1958 break; 1959 default: 1960 panic("hammer_btree_correct_rhb(): Bad node type"); 1961 error = EINVAL; 1962 break; 1963 } 1964 } 1965 1966 /* 1967 * Cleanup 1968 */ 1969 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 1970 TAILQ_REMOVE(&rhb_list, rhb, entry); 1971 hammer_unlock(&rhb->node->lock); 1972 hammer_rel_node(rhb->node); 1973 kfree(rhb, hmp->m_misc); 1974 } 1975 error = hammer_cursor_seek(cursor, orig_node, orig_index); 1976 hammer_unlock(&orig_node->lock); 1977 hammer_rel_node(orig_node); 1978 return (error); 1979 } 1980 1981 /* 1982 * Similar to rhb (in fact, rhb calls lhb), but corrects the left hand 1983 * bound going downward starting at the current cursor position. 1984 * 1985 * This function does not restore the cursor after use. 1986 */ 1987 int 1988 hammer_btree_correct_lhb(hammer_cursor_t cursor, hammer_tid_t tid) 1989 { 1990 struct hammer_rhb_list rhb_list; 1991 hammer_base_elm_t elm; 1992 hammer_base_elm_t cmp; 1993 struct hammer_rhb *rhb; 1994 struct hammer_mount *hmp; 1995 int error; 1996 1997 TAILQ_INIT(&rhb_list); 1998 hmp = cursor->trans->hmp; 1999 2000 cmp = &cursor->node->ondisk->elms[cursor->index].base; 2001 2002 /* 2003 * Record the node and traverse down the left-hand side for all 2004 * matching records needing a boundary correction. 2005 */ 2006 error = 0; 2007 for (;;) { 2008 rhb = kmalloc(sizeof(*rhb), hmp->m_misc, M_WAITOK|M_ZERO); 2009 rhb->node = cursor->node; 2010 rhb->index = cursor->index; 2011 hammer_ref_node(rhb->node); 2012 hammer_lock_sh(&rhb->node->lock); 2013 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry); 2014 2015 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2016 /* 2017 * Nothing to traverse down if we are at the right 2018 * boundary of an internal node. 2019 */ 2020 if (cursor->index == cursor->node->ondisk->count) 2021 break; 2022 } else { 2023 elm = &cursor->node->ondisk->elms[cursor->index].base; 2024 if (elm->btype == HAMMER_BTREE_TYPE_RECORD) 2025 break; 2026 panic("Illegal leaf record type %02x", elm->btype); 2027 } 2028 error = hammer_cursor_down(cursor); 2029 if (error) 2030 break; 2031 2032 elm = &cursor->node->ondisk->elms[cursor->index].base; 2033 if (elm->obj_id != cmp->obj_id || 2034 elm->rec_type != cmp->rec_type || 2035 elm->key != cmp->key) { 2036 break; 2037 } 2038 if (elm->create_tid >= tid) 2039 break; 2040 2041 } 2042 2043 /* 2044 * Now we can safely adjust the left-hand boundary from the bottom-up. 2045 * The last element we remove from the list is the caller's right hand 2046 * boundary, which must also be adjusted. 2047 */ 2048 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2049 error = hammer_cursor_seek(cursor, rhb->node, rhb->index); 2050 if (error) 2051 break; 2052 TAILQ_REMOVE(&rhb_list, rhb, entry); 2053 hammer_unlock(&rhb->node->lock); 2054 hammer_rel_node(rhb->node); 2055 kfree(rhb, hmp->m_misc); 2056 2057 elm = &cursor->node->ondisk->elms[cursor->index].base; 2058 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2059 hammer_modify_node(cursor->trans, cursor->node, 2060 &elm->create_tid, 2061 sizeof(elm->create_tid)); 2062 elm->create_tid = tid; 2063 hammer_modify_node_done(cursor->node); 2064 } else { 2065 panic("hammer_btree_correct_lhb(): Bad element type"); 2066 } 2067 } 2068 2069 /* 2070 * Cleanup 2071 */ 2072 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) { 2073 TAILQ_REMOVE(&rhb_list, rhb, entry); 2074 hammer_unlock(&rhb->node->lock); 2075 hammer_rel_node(rhb->node); 2076 kfree(rhb, hmp->m_misc); 2077 } 2078 return (error); 2079 } 2080 2081 #endif 2082 2083 /* 2084 * Attempt to remove the locked, empty or want-to-be-empty B-Tree node at 2085 * (cursor->node). Returns 0 on success, EDEADLK if we could not complete 2086 * the operation due to a deadlock, or some other error. 2087 * 2088 * This routine is initially called with an empty leaf and may be 2089 * recursively called with single-element internal nodes. 2090 * 2091 * It should also be noted that when removing empty leaves we must be sure 2092 * to test and update mirror_tid because another thread may have deadlocked 2093 * against us (or someone) trying to propagate it up and cannot retry once 2094 * the node has been deleted. 2095 * 2096 * On return the cursor may end up pointing to an internal node, suitable 2097 * for further iteration but not for an immediate insertion or deletion. 2098 */ 2099 static int 2100 btree_remove(hammer_cursor_t cursor) 2101 { 2102 hammer_node_ondisk_t ondisk; 2103 hammer_btree_elm_t elm; 2104 hammer_node_t node; 2105 hammer_node_t parent; 2106 const int esize = sizeof(*elm); 2107 int error; 2108 2109 node = cursor->node; 2110 2111 /* 2112 * When deleting the root of the filesystem convert it to 2113 * an empty leaf node. Internal nodes cannot be empty. 2114 */ 2115 ondisk = node->ondisk; 2116 if (ondisk->parent == 0) { 2117 KKASSERT(cursor->parent == NULL); 2118 hammer_modify_node_all(cursor->trans, node); 2119 KKASSERT(ondisk == node->ondisk); 2120 ondisk->type = HAMMER_BTREE_TYPE_LEAF; 2121 ondisk->count = 0; 2122 hammer_modify_node_done(node); 2123 cursor->index = 0; 2124 return(0); 2125 } 2126 2127 parent = cursor->parent; 2128 hammer_cursor_removed_node(node, parent, cursor->parent_index); 2129 2130 /* 2131 * Attempt to remove the parent's reference to the child. If the 2132 * parent would become empty we have to recurse. If we fail we 2133 * leave the parent pointing to an empty leaf node. 2134 * 2135 * We have to recurse successfully before we can delete the internal 2136 * node as it is illegal to have empty internal nodes. Even though 2137 * the operation may be aborted we must still fixup any unlocked 2138 * cursors as if we had deleted the element prior to recursing 2139 * (by calling hammer_cursor_deleted_element()) so those cursors 2140 * are properly forced up the chain by the recursion. 2141 */ 2142 if (parent->ondisk->count == 1) { 2143 /* 2144 * This special cursor_up_locked() call leaves the original 2145 * node exclusively locked and referenced, leaves the 2146 * original parent locked (as the new node), and locks the 2147 * new parent. It can return EDEADLK. 2148 */ 2149 error = hammer_cursor_up_locked(cursor); 2150 if (error == 0) { 2151 hammer_cursor_deleted_element(cursor->node, 0); 2152 error = btree_remove(cursor); 2153 if (error == 0) { 2154 hammer_modify_node_all(cursor->trans, node); 2155 ondisk = node->ondisk; 2156 ondisk->type = HAMMER_BTREE_TYPE_DELETED; 2157 ondisk->count = 0; 2158 hammer_modify_node_done(node); 2159 hammer_flush_node(node); 2160 hammer_delete_node(cursor->trans, node); 2161 } else { 2162 kprintf("Warning: BTREE_REMOVE: Defering " 2163 "parent removal1 @ %016llx, skipping\n", 2164 node->node_offset); 2165 } 2166 hammer_unlock(&node->lock); 2167 hammer_rel_node(node); 2168 } else { 2169 kprintf("Warning: BTREE_REMOVE: Defering parent " 2170 "removal2 @ %016llx, skipping\n", 2171 node->node_offset); 2172 } 2173 } else { 2174 KKASSERT(parent->ondisk->count > 1); 2175 2176 hammer_modify_node_all(cursor->trans, parent); 2177 ondisk = parent->ondisk; 2178 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_INTERNAL); 2179 2180 elm = &ondisk->elms[cursor->parent_index]; 2181 KKASSERT(elm->internal.subtree_offset == node->node_offset); 2182 KKASSERT(ondisk->count > 0); 2183 2184 /* 2185 * We must retain the highest mirror_tid. The deleted 2186 * range is now encompassed by the element to the left. 2187 * If we are already at the left edge the new left edge 2188 * inherits mirror_tid. 2189 * 2190 * Note that bounds of the parent to our parent may create 2191 * a gap to the left of our left-most node or to the right 2192 * of our right-most node. The gap is silently included 2193 * in the mirror_tid's area of effect from the point of view 2194 * of the scan. 2195 */ 2196 if (cursor->parent_index) { 2197 if (elm[-1].internal.mirror_tid < 2198 elm[0].internal.mirror_tid) { 2199 elm[-1].internal.mirror_tid = 2200 elm[0].internal.mirror_tid; 2201 } 2202 } else { 2203 if (elm[1].internal.mirror_tid < 2204 elm[0].internal.mirror_tid) { 2205 elm[1].internal.mirror_tid = 2206 elm[0].internal.mirror_tid; 2207 } 2208 } 2209 2210 /* 2211 * Delete the subtree reference in the parent 2212 */ 2213 bcopy(&elm[1], &elm[0], 2214 (ondisk->count - cursor->parent_index) * esize); 2215 --ondisk->count; 2216 hammer_modify_node_done(parent); 2217 hammer_cursor_deleted_element(parent, cursor->parent_index); 2218 hammer_flush_node(node); 2219 hammer_delete_node(cursor->trans, node); 2220 2221 /* 2222 * cursor->node is invalid, cursor up to make the cursor 2223 * valid again. 2224 */ 2225 error = hammer_cursor_up(cursor); 2226 } 2227 return (error); 2228 } 2229 2230 /* 2231 * Propagate cursor->trans->tid up the B-Tree starting at the current 2232 * cursor position using pseudofs info gleaned from the passed inode. 2233 * 2234 * The passed inode has no relationship to the cursor position other 2235 * then being in the same pseudofs as the insertion or deletion we 2236 * are propagating the mirror_tid for. 2237 */ 2238 void 2239 hammer_btree_do_propagation(hammer_cursor_t cursor, 2240 hammer_pseudofs_inmem_t pfsm, 2241 hammer_btree_leaf_elm_t leaf) 2242 { 2243 hammer_cursor_t ncursor; 2244 hammer_tid_t mirror_tid; 2245 int error; 2246 2247 /* 2248 * We do not propagate a mirror_tid if the filesystem was mounted 2249 * in no-mirror mode. 2250 */ 2251 if (cursor->trans->hmp->master_id < 0) 2252 return; 2253 2254 /* 2255 * This is a bit of a hack because we cannot deadlock or return 2256 * EDEADLK here. The related operation has already completed and 2257 * we must propagate the mirror_tid now regardless. 2258 * 2259 * Generate a new cursor which inherits the original's locks and 2260 * unlock the original. Use the new cursor to propagate the 2261 * mirror_tid. Then clean up the new cursor and reacquire locks 2262 * on the original. 2263 * 2264 * hammer_dup_cursor() cannot dup locks. The dup inherits the 2265 * original's locks and the original is tracked and must be 2266 * re-locked. 2267 */ 2268 mirror_tid = cursor->node->ondisk->mirror_tid; 2269 KKASSERT(mirror_tid != 0); 2270 ncursor = hammer_push_cursor(cursor); 2271 error = hammer_btree_mirror_propagate(ncursor, mirror_tid); 2272 KKASSERT(error == 0); 2273 hammer_pop_cursor(cursor, ncursor); 2274 } 2275 2276 2277 /* 2278 * Propagate a mirror TID update upwards through the B-Tree to the root. 2279 * 2280 * A locked internal node must be passed in. The node will remain locked 2281 * on return. 2282 * 2283 * This function syncs mirror_tid at the specified internal node's element, 2284 * adjusts the node's aggregation mirror_tid, and then recurses upwards. 2285 */ 2286 static int 2287 hammer_btree_mirror_propagate(hammer_cursor_t cursor, hammer_tid_t mirror_tid) 2288 { 2289 hammer_btree_internal_elm_t elm; 2290 hammer_node_t node; 2291 int error; 2292 2293 for (;;) { 2294 error = hammer_cursor_up(cursor); 2295 if (error == 0) 2296 error = hammer_cursor_upgrade(cursor); 2297 while (error == EDEADLK) { 2298 hammer_recover_cursor(cursor); 2299 error = hammer_cursor_upgrade(cursor); 2300 } 2301 if (error) 2302 break; 2303 node = cursor->node; 2304 KKASSERT (node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL); 2305 2306 /* 2307 * Adjust the node's element 2308 */ 2309 elm = &node->ondisk->elms[cursor->index].internal; 2310 if (elm->mirror_tid >= mirror_tid) 2311 break; 2312 hammer_modify_node(cursor->trans, node, &elm->mirror_tid, 2313 sizeof(elm->mirror_tid)); 2314 elm->mirror_tid = mirror_tid; 2315 hammer_modify_node_done(node); 2316 if (hammer_debug_general & 0x0002) { 2317 kprintf("mirror_propagate: propagate " 2318 "%016llx @%016llx:%d\n", 2319 mirror_tid, node->node_offset, cursor->index); 2320 } 2321 2322 2323 /* 2324 * Adjust the node's mirror_tid aggregator 2325 */ 2326 if (node->ondisk->mirror_tid >= mirror_tid) 2327 return(0); 2328 hammer_modify_node_field(cursor->trans, node, mirror_tid); 2329 node->ondisk->mirror_tid = mirror_tid; 2330 hammer_modify_node_done(node); 2331 if (hammer_debug_general & 0x0002) { 2332 kprintf("mirror_propagate: propagate " 2333 "%016llx @%016llx\n", 2334 mirror_tid, node->node_offset); 2335 } 2336 } 2337 if (error == ENOENT) 2338 error = 0; 2339 return(error); 2340 } 2341 2342 hammer_node_t 2343 hammer_btree_get_parent(hammer_transaction_t trans, hammer_node_t node, 2344 int *parent_indexp, int *errorp, int try_exclusive) 2345 { 2346 hammer_node_t parent; 2347 hammer_btree_elm_t elm; 2348 int i; 2349 2350 /* 2351 * Get the node 2352 */ 2353 parent = hammer_get_node(trans, node->ondisk->parent, 0, errorp); 2354 if (*errorp) { 2355 KKASSERT(parent == NULL); 2356 return(NULL); 2357 } 2358 KKASSERT ((parent->flags & HAMMER_NODE_DELETED) == 0); 2359 2360 /* 2361 * Lock the node 2362 */ 2363 if (try_exclusive) { 2364 if (hammer_lock_ex_try(&parent->lock)) { 2365 hammer_rel_node(parent); 2366 *errorp = EDEADLK; 2367 return(NULL); 2368 } 2369 } else { 2370 hammer_lock_sh(&parent->lock); 2371 } 2372 2373 /* 2374 * Figure out which element in the parent is pointing to the 2375 * child. 2376 */ 2377 if (node->ondisk->count) { 2378 i = hammer_btree_search_node(&node->ondisk->elms[0].base, 2379 parent->ondisk); 2380 } else { 2381 i = 0; 2382 } 2383 while (i < parent->ondisk->count) { 2384 elm = &parent->ondisk->elms[i]; 2385 if (elm->internal.subtree_offset == node->node_offset) 2386 break; 2387 ++i; 2388 } 2389 if (i == parent->ondisk->count) { 2390 hammer_unlock(&parent->lock); 2391 panic("Bad B-Tree link: parent %p node %p\n", parent, node); 2392 } 2393 *parent_indexp = i; 2394 KKASSERT(*errorp == 0); 2395 return(parent); 2396 } 2397 2398 /* 2399 * The element (elm) has been moved to a new internal node (node). 2400 * 2401 * If the element represents a pointer to an internal node that node's 2402 * parent must be adjusted to the element's new location. 2403 * 2404 * XXX deadlock potential here with our exclusive locks 2405 */ 2406 int 2407 btree_set_parent(hammer_transaction_t trans, hammer_node_t node, 2408 hammer_btree_elm_t elm) 2409 { 2410 hammer_node_t child; 2411 int error; 2412 2413 error = 0; 2414 2415 switch(elm->base.btype) { 2416 case HAMMER_BTREE_TYPE_INTERNAL: 2417 case HAMMER_BTREE_TYPE_LEAF: 2418 child = hammer_get_node(trans, elm->internal.subtree_offset, 2419 0, &error); 2420 if (error == 0) { 2421 hammer_modify_node_field(trans, child, parent); 2422 child->ondisk->parent = node->node_offset; 2423 hammer_modify_node_done(child); 2424 hammer_rel_node(child); 2425 } 2426 break; 2427 default: 2428 break; 2429 } 2430 return(error); 2431 } 2432 2433 /* 2434 * Initialize the root of a recursive B-Tree node lock list structure. 2435 */ 2436 void 2437 hammer_node_lock_init(hammer_node_lock_t parent, hammer_node_t node) 2438 { 2439 TAILQ_INIT(&parent->list); 2440 parent->parent = NULL; 2441 parent->node = node; 2442 parent->index = -1; 2443 parent->count = node->ondisk->count; 2444 parent->copy = NULL; 2445 parent->flags = 0; 2446 } 2447 2448 /* 2449 * Exclusively lock all the children of node. This is used by the split 2450 * code to prevent anyone from accessing the children of a cursor node 2451 * while we fix-up its parent offset. 2452 * 2453 * If we don't lock the children we can really mess up cursors which block 2454 * trying to cursor-up into our node. 2455 * 2456 * On failure EDEADLK (or some other error) is returned. If a deadlock 2457 * error is returned the cursor is adjusted to block on termination. 2458 * 2459 * The caller is responsible for managing parent->node, the root's node 2460 * is usually aliased from a cursor. 2461 */ 2462 int 2463 hammer_btree_lock_children(hammer_cursor_t cursor, int depth, 2464 hammer_node_lock_t parent) 2465 { 2466 hammer_node_t node; 2467 hammer_node_lock_t item; 2468 hammer_node_ondisk_t ondisk; 2469 hammer_btree_elm_t elm; 2470 hammer_node_t child; 2471 struct hammer_mount *hmp; 2472 int error; 2473 int i; 2474 2475 node = parent->node; 2476 ondisk = node->ondisk; 2477 error = 0; 2478 hmp = cursor->trans->hmp; 2479 2480 /* 2481 * We really do not want to block on I/O with exclusive locks held, 2482 * pre-get the children before trying to lock the mess. This is 2483 * only done one-level deep for now. 2484 */ 2485 for (i = 0; i < ondisk->count; ++i) { 2486 ++hammer_stats_btree_elements; 2487 elm = &ondisk->elms[i]; 2488 if (elm->base.btype != HAMMER_BTREE_TYPE_LEAF && 2489 elm->base.btype != HAMMER_BTREE_TYPE_INTERNAL) { 2490 continue; 2491 } 2492 child = hammer_get_node(cursor->trans, 2493 elm->internal.subtree_offset, 2494 0, &error); 2495 if (child) 2496 hammer_rel_node(child); 2497 } 2498 2499 /* 2500 * Do it for real 2501 */ 2502 for (i = 0; error == 0 && i < ondisk->count; ++i) { 2503 ++hammer_stats_btree_elements; 2504 elm = &ondisk->elms[i]; 2505 2506 switch(elm->base.btype) { 2507 case HAMMER_BTREE_TYPE_INTERNAL: 2508 case HAMMER_BTREE_TYPE_LEAF: 2509 KKASSERT(elm->internal.subtree_offset != 0); 2510 child = hammer_get_node(cursor->trans, 2511 elm->internal.subtree_offset, 2512 0, &error); 2513 break; 2514 default: 2515 child = NULL; 2516 break; 2517 } 2518 if (child) { 2519 if (hammer_lock_ex_try(&child->lock) != 0) { 2520 if (cursor->deadlk_node == NULL) { 2521 cursor->deadlk_node = child; 2522 hammer_ref_node(cursor->deadlk_node); 2523 } 2524 error = EDEADLK; 2525 hammer_rel_node(child); 2526 } else { 2527 item = kmalloc(sizeof(*item), hmp->m_misc, 2528 M_WAITOK|M_ZERO); 2529 TAILQ_INSERT_TAIL(&parent->list, item, entry); 2530 TAILQ_INIT(&item->list); 2531 item->parent = parent; 2532 item->node = child; 2533 item->index = i; 2534 item->count = child->ondisk->count; 2535 2536 /* 2537 * Recurse (used by the rebalancing code) 2538 */ 2539 if (depth > 1 && elm->base.btype == HAMMER_BTREE_TYPE_INTERNAL) { 2540 error = hammer_btree_lock_children( 2541 cursor, 2542 depth - 1, 2543 item); 2544 } 2545 } 2546 } 2547 } 2548 if (error) 2549 hammer_btree_unlock_children(cursor, parent); 2550 return(error); 2551 } 2552 2553 /* 2554 * Create an in-memory copy of all B-Tree nodes listed, recursively, 2555 * including the parent. 2556 */ 2557 void 2558 hammer_btree_lock_copy(hammer_cursor_t cursor, hammer_node_lock_t parent) 2559 { 2560 hammer_mount_t hmp = cursor->trans->hmp; 2561 hammer_node_lock_t item; 2562 2563 if (parent->copy == NULL) { 2564 parent->copy = kmalloc(sizeof(*parent->copy), hmp->m_misc, 2565 M_WAITOK); 2566 *parent->copy = *parent->node->ondisk; 2567 } 2568 TAILQ_FOREACH(item, &parent->list, entry) { 2569 hammer_btree_lock_copy(cursor, item); 2570 } 2571 } 2572 2573 /* 2574 * Recursively sync modified copies to the media. 2575 */ 2576 int 2577 hammer_btree_sync_copy(hammer_cursor_t cursor, hammer_node_lock_t parent) 2578 { 2579 hammer_node_lock_t item; 2580 int count = 0; 2581 2582 if (parent->flags & HAMMER_NODE_LOCK_UPDATED) { 2583 ++count; 2584 hammer_modify_node_all(cursor->trans, parent->node); 2585 *parent->node->ondisk = *parent->copy; 2586 hammer_modify_node_done(parent->node); 2587 if (parent->copy->type == HAMMER_BTREE_TYPE_DELETED) { 2588 hammer_flush_node(parent->node); 2589 hammer_delete_node(cursor->trans, parent->node); 2590 } 2591 } 2592 TAILQ_FOREACH(item, &parent->list, entry) { 2593 count += hammer_btree_sync_copy(cursor, item); 2594 } 2595 return(count); 2596 } 2597 2598 /* 2599 * Release previously obtained node locks. The caller is responsible for 2600 * cleaning up parent->node itself (its usually just aliased from a cursor), 2601 * but this function will take care of the copies. 2602 */ 2603 void 2604 hammer_btree_unlock_children(hammer_cursor_t cursor, hammer_node_lock_t parent) 2605 { 2606 hammer_node_lock_t item; 2607 2608 if (parent->copy) { 2609 kfree(parent->copy, cursor->trans->hmp->m_misc); 2610 parent->copy = NULL; /* safety */ 2611 } 2612 while ((item = TAILQ_FIRST(&parent->list)) != NULL) { 2613 TAILQ_REMOVE(&parent->list, item, entry); 2614 hammer_btree_unlock_children(cursor, item); 2615 hammer_unlock(&item->node->lock); 2616 hammer_rel_node(item->node); 2617 kfree(item, cursor->trans->hmp->m_misc); 2618 } 2619 } 2620 2621 /************************************************************************ 2622 * MISCELLANIOUS SUPPORT * 2623 ************************************************************************/ 2624 2625 /* 2626 * Compare two B-Tree elements, return -N, 0, or +N (e.g. similar to strcmp). 2627 * 2628 * Note that for this particular function a return value of -1, 0, or +1 2629 * can denote a match if create_tid is otherwise discounted. A create_tid 2630 * of zero is considered to be 'infinity' in comparisons. 2631 * 2632 * See also hammer_rec_rb_compare() and hammer_rec_cmp() in hammer_object.c. 2633 */ 2634 int 2635 hammer_btree_cmp(hammer_base_elm_t key1, hammer_base_elm_t key2) 2636 { 2637 if (key1->localization < key2->localization) 2638 return(-5); 2639 if (key1->localization > key2->localization) 2640 return(5); 2641 2642 if (key1->obj_id < key2->obj_id) 2643 return(-4); 2644 if (key1->obj_id > key2->obj_id) 2645 return(4); 2646 2647 if (key1->rec_type < key2->rec_type) 2648 return(-3); 2649 if (key1->rec_type > key2->rec_type) 2650 return(3); 2651 2652 if (key1->key < key2->key) 2653 return(-2); 2654 if (key1->key > key2->key) 2655 return(2); 2656 2657 /* 2658 * A create_tid of zero indicates a record which is undeletable 2659 * and must be considered to have a value of positive infinity. 2660 */ 2661 if (key1->create_tid == 0) { 2662 if (key2->create_tid == 0) 2663 return(0); 2664 return(1); 2665 } 2666 if (key2->create_tid == 0) 2667 return(-1); 2668 if (key1->create_tid < key2->create_tid) 2669 return(-1); 2670 if (key1->create_tid > key2->create_tid) 2671 return(1); 2672 return(0); 2673 } 2674 2675 /* 2676 * Test a timestamp against an element to determine whether the 2677 * element is visible. A timestamp of 0 means 'infinity'. 2678 */ 2679 int 2680 hammer_btree_chkts(hammer_tid_t asof, hammer_base_elm_t base) 2681 { 2682 if (asof == 0) { 2683 if (base->delete_tid) 2684 return(1); 2685 return(0); 2686 } 2687 if (asof < base->create_tid) 2688 return(-1); 2689 if (base->delete_tid && asof >= base->delete_tid) 2690 return(1); 2691 return(0); 2692 } 2693 2694 /* 2695 * Create a separator half way inbetween key1 and key2. For fields just 2696 * one unit apart, the separator will match key2. key1 is on the left-hand 2697 * side and key2 is on the right-hand side. 2698 * 2699 * key2 must be >= the separator. It is ok for the separator to match key2. 2700 * 2701 * NOTE: Even if key1 does not match key2, the separator may wind up matching 2702 * key2. 2703 * 2704 * NOTE: It might be beneficial to just scrap this whole mess and just 2705 * set the separator to key2. 2706 */ 2707 #define MAKE_SEPARATOR(key1, key2, dest, field) \ 2708 dest->field = key1->field + ((key2->field - key1->field + 1) >> 1); 2709 2710 static void 2711 hammer_make_separator(hammer_base_elm_t key1, hammer_base_elm_t key2, 2712 hammer_base_elm_t dest) 2713 { 2714 bzero(dest, sizeof(*dest)); 2715 2716 dest->rec_type = key2->rec_type; 2717 dest->key = key2->key; 2718 dest->obj_id = key2->obj_id; 2719 dest->create_tid = key2->create_tid; 2720 2721 MAKE_SEPARATOR(key1, key2, dest, localization); 2722 if (key1->localization == key2->localization) { 2723 MAKE_SEPARATOR(key1, key2, dest, obj_id); 2724 if (key1->obj_id == key2->obj_id) { 2725 MAKE_SEPARATOR(key1, key2, dest, rec_type); 2726 if (key1->rec_type == key2->rec_type) { 2727 MAKE_SEPARATOR(key1, key2, dest, key); 2728 /* 2729 * Don't bother creating a separator for 2730 * create_tid, which also conveniently avoids 2731 * having to handle the create_tid == 0 2732 * (infinity) case. Just leave create_tid 2733 * set to key2. 2734 * 2735 * Worst case, dest matches key2 exactly, 2736 * which is acceptable. 2737 */ 2738 } 2739 } 2740 } 2741 } 2742 2743 #undef MAKE_SEPARATOR 2744 2745 /* 2746 * Return whether a generic internal or leaf node is full 2747 */ 2748 static int 2749 btree_node_is_full(hammer_node_ondisk_t node) 2750 { 2751 switch(node->type) { 2752 case HAMMER_BTREE_TYPE_INTERNAL: 2753 if (node->count == HAMMER_BTREE_INT_ELMS) 2754 return(1); 2755 break; 2756 case HAMMER_BTREE_TYPE_LEAF: 2757 if (node->count == HAMMER_BTREE_LEAF_ELMS) 2758 return(1); 2759 break; 2760 default: 2761 panic("illegal btree subtype"); 2762 } 2763 return(0); 2764 } 2765 2766 #if 0 2767 static int 2768 btree_max_elements(u_int8_t type) 2769 { 2770 if (type == HAMMER_BTREE_TYPE_LEAF) 2771 return(HAMMER_BTREE_LEAF_ELMS); 2772 if (type == HAMMER_BTREE_TYPE_INTERNAL) 2773 return(HAMMER_BTREE_INT_ELMS); 2774 panic("btree_max_elements: bad type %d\n", type); 2775 } 2776 #endif 2777 2778 void 2779 hammer_print_btree_node(hammer_node_ondisk_t ondisk) 2780 { 2781 hammer_btree_elm_t elm; 2782 int i; 2783 2784 kprintf("node %p count=%d parent=%016llx type=%c\n", 2785 ondisk, ondisk->count, ondisk->parent, ondisk->type); 2786 2787 /* 2788 * Dump both boundary elements if an internal node 2789 */ 2790 if (ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) { 2791 for (i = 0; i <= ondisk->count; ++i) { 2792 elm = &ondisk->elms[i]; 2793 hammer_print_btree_elm(elm, ondisk->type, i); 2794 } 2795 } else { 2796 for (i = 0; i < ondisk->count; ++i) { 2797 elm = &ondisk->elms[i]; 2798 hammer_print_btree_elm(elm, ondisk->type, i); 2799 } 2800 } 2801 } 2802 2803 void 2804 hammer_print_btree_elm(hammer_btree_elm_t elm, u_int8_t type, int i) 2805 { 2806 kprintf(" %2d", i); 2807 kprintf("\tobj_id = %016llx\n", elm->base.obj_id); 2808 kprintf("\tkey = %016llx\n", elm->base.key); 2809 kprintf("\tcreate_tid = %016llx\n", elm->base.create_tid); 2810 kprintf("\tdelete_tid = %016llx\n", elm->base.delete_tid); 2811 kprintf("\trec_type = %04x\n", elm->base.rec_type); 2812 kprintf("\tobj_type = %02x\n", elm->base.obj_type); 2813 kprintf("\tbtype = %02x (%c)\n", 2814 elm->base.btype, 2815 (elm->base.btype ? elm->base.btype : '?')); 2816 kprintf("\tlocalization = %02x\n", elm->base.localization); 2817 2818 switch(type) { 2819 case HAMMER_BTREE_TYPE_INTERNAL: 2820 kprintf("\tsubtree_off = %016llx\n", 2821 elm->internal.subtree_offset); 2822 break; 2823 case HAMMER_BTREE_TYPE_RECORD: 2824 kprintf("\tdata_offset = %016llx\n", elm->leaf.data_offset); 2825 kprintf("\tdata_len = %08x\n", elm->leaf.data_len); 2826 kprintf("\tdata_crc = %08x\n", elm->leaf.data_crc); 2827 break; 2828 } 2829 } 2830