sys/vfs/hammer/hammer_btree.c

   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 1.63 2008/07/05 18:59:27 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_transaction_t trans,
  91                         hammer_node_t node, int index, 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
  95 /*
  96  * Iterate records after a search.  The cursor is iterated forwards past
  97  * the current record until a record matching the key-range requirements
  98  * is found.  ENOENT is returned if the iteration goes past the ending
  99  * key.
 100  *
 101  * The iteration is inclusive of key_beg and can be inclusive or exclusive
 102  * of key_end depending on whether HAMMER_CURSOR_END_INCLUSIVE is set.
 103  *
 104  * When doing an as-of search (cursor->asof != 0), key_beg.create_tid
 105  * may be modified by B-Tree functions.
 106  *
 107  * cursor->key_beg may or may not be modified by this function during
 108  * the iteration.  XXX future - in case of an inverted lock we may have
 109  * to reinitiate the lookup and set key_beg to properly pick up where we
 110  * left off.
 111  *
 112  * NOTE!  EDEADLK *CANNOT* be returned by this procedure.
 113  */
 114 int
 115 hammer_btree_iterate(hammer_cursor_t cursor)
 116 {
 117         hammer_node_ondisk_t node;
 118         hammer_btree_elm_t elm;
 119         int error;
 120         int r;
 121         int s;
 122
 123         /*
 124          * Skip past the current record
 125          */
 126         node = cursor->node->ondisk;
 127         if (node == NULL)
 128                 return(ENOENT);
 129         if (cursor->index < node->count &&
 130             (cursor->flags & HAMMER_CURSOR_ATEDISK)) {
 131                 ++cursor->index;
 132         }
 133
 134         /*
 135          * Loop until an element is found or we are done.
 136          */
 137         for (;;) {
 138                 /*
 139                  * We iterate up the tree and then index over one element
 140                  * while we are at the last element in the current node.
 141                  *
 142                  * If we are at the root of the filesystem, cursor_up
 143                  * returns ENOENT.
 144                  *
 145                  * XXX this could be optimized by storing the information in
 146                  * the parent reference.
 147                  *
 148                  * XXX we can lose the node lock temporarily, this could mess
 149                  * up our scan.
 150                  */
 151                 ++hammer_stats_btree_iterations;
 152                 hammer_flusher_clean_loose_ios(cursor->trans->hmp);
 153
 154                 if (cursor->index == node->count) {
 155                         if (hammer_debug_btree) {
 156                                 kprintf("BRACKETU %016llx[%d] -> %016llx[%d] (td=%p)\n",
 157                                         cursor->node->node_offset,
 158                                         cursor->index,
 159                                         (cursor->parent ? cursor->parent->node_offset : -1),
 160                                         cursor->parent_index,
 161                                         curthread);
 162                         }
 163                         KKASSERT(cursor->parent == NULL || cursor->parent->ondisk->elms[cursor->parent_index].internal.subtree_offset == cursor->node->node_offset);
 164                         error = hammer_cursor_up(cursor);
 165                         if (error)
 166                                 break;
 167                         /* reload stale pointer */
 168                         node = cursor->node->ondisk;
 169                         KKASSERT(cursor->index != node->count);
 170
 171                         /*
 172                          * If we are reblocking we want to return internal
 173                          * nodes.
 174                          */
 175                         if (cursor->flags & HAMMER_CURSOR_REBLOCKING) {
 176                                 cursor->flags |= HAMMER_CURSOR_ATEDISK;
 177                                 return(0);
 178                         }
 179                         ++cursor->index;
 180                         continue;
 181                 }
 182
 183                 /*
 184                  * Check internal or leaf element.  Determine if the record
 185                  * at the cursor has gone beyond the end of our range.
 186                  *
 187                  * We recurse down through internal nodes.
 188                  */
 189                 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) {
 190                         elm = &node->elms[cursor->index];
 191
 192                         r = hammer_btree_cmp(&cursor->key_end, &elm[0].base);
 193                         s = hammer_btree_cmp(&cursor->key_beg, &elm[1].base);
 194                         if (hammer_debug_btree) {
 195                                 kprintf("BRACKETL %016llx[%d] %016llx %02x %016llx lo=%02x %d (td=%p)\n",
 196                                         cursor->node->node_offset,
 197                                         cursor->index,
 198                                         elm[0].internal.base.obj_id,
 199                                         elm[0].internal.base.rec_type,
 200                                         elm[0].internal.base.key,
 201                                         elm[0].internal.base.localization,
 202                                         r,
 203                                         curthread
 204                                 );
 205                                 kprintf("BRACKETR %016llx[%d] %016llx %02x %016llx lo=%02x %d\n",
 206                                         cursor->node->node_offset,
 207                                         cursor->index + 1,
 208                                         elm[1].internal.base.obj_id,
 209                                         elm[1].internal.base.rec_type,
 210                                         elm[1].internal.base.key,
 211                                         elm[1].internal.base.localization,
 212                                         s
 213                                 );
 214                         }
 215
 216                         if (r < 0) {
 217                                 error = ENOENT;
 218                                 break;
 219                         }
 220                         if (r == 0 && (cursor->flags &
 221                                        HAMMER_CURSOR_END_INCLUSIVE) == 0) {
 222                                 error = ENOENT;
 223                                 break;
 224                         }
 225                         KKASSERT(s <= 0);
 226
 227                         /*
 228                          * Better not be zero
 229                          */
 230                         KKASSERT(elm->internal.subtree_offset != 0);
 231
 232                         /*
 233                          * If running the mirror filter see if we can skip
 234                          * the entire sub-tree.
 235                          */
 236                         if (cursor->flags & HAMMER_CURSOR_MIRROR_FILTERED) {
 237                                 if (elm->internal.mirror_tid <
 238                                     cursor->mirror_tid) {
 239                                         ++cursor->index;
 240                                         continue;
 241                                 }
 242                         }
 243
 244                         error = hammer_cursor_down(cursor);
 245                         if (error)
 246                                 break;
 247                         KKASSERT(cursor->index == 0);
 248                         /* reload stale pointer */
 249                         node = cursor->node->ondisk;
 250                         continue;
 251                 } else {
 252                         elm = &node->elms[cursor->index];
 253                         r = hammer_btree_cmp(&cursor->key_end, &elm->base);
 254                         if (hammer_debug_btree) {
 255                                 kprintf("ELEMENT  %016llx:%d %c %016llx %02x %016llx lo=%02x %d\n",
 256                                         cursor->node->node_offset,
 257                                         cursor->index,
 258                                         (elm[0].leaf.base.btype ?
 259                                          elm[0].leaf.base.btype : '?'),
 260                                         elm[0].leaf.base.obj_id,
 261                                         elm[0].leaf.base.rec_type,
 262                                         elm[0].leaf.base.key,
 263                                         elm[0].leaf.base.localization,
 264                                         r
 265                                 );
 266                         }
 267                         if (r < 0) {
 268                                 error = ENOENT;
 269                                 break;
 270                         }
 271
 272                         /*
 273                          * We support both end-inclusive and
 274                          * end-exclusive searches.
 275                          */
 276                         if (r == 0 &&
 277                            (cursor->flags & HAMMER_CURSOR_END_INCLUSIVE) == 0) {
 278                                 error = ENOENT;
 279                                 break;
 280                         }
 281
 282                         switch(elm->leaf.base.btype) {
 283                         case HAMMER_BTREE_TYPE_RECORD:
 284                                 if ((cursor->flags & HAMMER_CURSOR_ASOF) &&
 285                                     hammer_btree_chkts(cursor->asof, &elm->base)) {
 286                                         ++cursor->index;
 287                                         continue;
 288                                 }
 289                                 break;
 290                         default:
 291                                 error = EINVAL;
 292                                 break;
 293                         }
 294                         if (error)
 295                                 break;
 296                 }
 297                 /*
 298                  * node pointer invalid after loop
 299                  */
 300
 301                 /*
 302                  * Return entry
 303                  */
 304                 if (hammer_debug_btree) {
 305                         int i = cursor->index;
 306                         hammer_btree_elm_t elm = &cursor->node->ondisk->elms[i];
 307                         kprintf("ITERATE  %p:%d %016llx %02x %016llx lo=%02x\n",
 308                                 cursor->node, i,
 309                                 elm->internal.base.obj_id,
 310                                 elm->internal.base.rec_type,
 311                                 elm->internal.base.key,
 312                                 elm->internal.base.localization
 313                         );
 314                 }
 315                 return(0);
 316         }
 317         return(error);
 318 }
 319
 320 /*
 321  * Iterate in the reverse direction.  This is used by the pruning code to
 322  * avoid overlapping records.
 323  */
 324 int
 325 hammer_btree_iterate_reverse(hammer_cursor_t cursor)
 326 {
 327         hammer_node_ondisk_t node;
 328         hammer_btree_elm_t elm;
 329         int error;
 330         int r;
 331         int s;
 332
 333         /*
 334          * Skip past the current record.  For various reasons the cursor
 335          * may end up set to -1 or set to point at the end of the current
 336          * node.  These cases must be addressed.
 337          */
 338         node = cursor->node->ondisk;
 339         if (node == NULL)
 340                 return(ENOENT);
 341         if (cursor->index != -1 &&
 342             (cursor->flags & HAMMER_CURSOR_ATEDISK)) {
 343                 --cursor->index;
 344         }
 345         if (cursor->index == cursor->node->ondisk->count)
 346                 --cursor->index;
 347
 348         /*
 349          * Loop until an element is found or we are done.
 350          */
 351         for (;;) {
 352                 ++hammer_stats_btree_iterations;
 353                 hammer_flusher_clean_loose_ios(cursor->trans->hmp);
 354
 355                 /*
 356                  * We iterate up the tree and then index over one element
 357                  * while we are at the last element in the current node.
 358                  */
 359                 if (cursor->index == -1) {
 360                         error = hammer_cursor_up(cursor);
 361                         if (error) {
 362                                 cursor->index = 0; /* sanity */
 363                                 break;
 364                         }
 365                         /* reload stale pointer */
 366                         node = cursor->node->ondisk;
 367                         KKASSERT(cursor->index != node->count);
 368                         --cursor->index;
 369                         continue;
 370                 }
 371
 372                 /*
 373                  * Check internal or leaf element.  Determine if the record
 374                  * at the cursor has gone beyond the end of our range.
 375                  *
 376                  * We recurse down through internal nodes.
 377                  */
 378                 KKASSERT(cursor->index != node->count);
 379                 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) {
 380                         elm = &node->elms[cursor->index];
 381                         r = hammer_btree_cmp(&cursor->key_end, &elm[0].base);
 382                         s = hammer_btree_cmp(&cursor->key_beg, &elm[1].base);
 383                         if (hammer_debug_btree) {
 384                                 kprintf("BRACKETL %016llx[%d] %016llx %02x %016llx lo=%02x %d\n",
 385                                         cursor->node->node_offset,
 386                                         cursor->index,
 387                                         elm[0].internal.base.obj_id,
 388                                         elm[0].internal.base.rec_type,
 389                                         elm[0].internal.base.key,
 390                                         elm[0].internal.base.localization,
 391                                         r
 392                                 );
 393                                 kprintf("BRACKETR %016llx[%d] %016llx %02x %016llx lo=%02x %d\n",
 394                                         cursor->node->node_offset,
 395                                         cursor->index + 1,
 396                                         elm[1].internal.base.obj_id,
 397                                         elm[1].internal.base.rec_type,
 398                                         elm[1].internal.base.key,
 399                                         elm[1].internal.base.localization,
 400                                         s
 401                                 );
 402                         }
 403
 404                         if (s >= 0) {
 405                                 error = ENOENT;
 406                                 break;
 407                         }
 408                         KKASSERT(r >= 0);
 409
 410                         /*
 411                          * Better not be zero
 412                          */
 413                         KKASSERT(elm->internal.subtree_offset != 0);
 414
 415                         error = hammer_cursor_down(cursor);
 416                         if (error)
 417                                 break;
 418                         KKASSERT(cursor->index == 0);
 419                         /* reload stale pointer */
 420                         node = cursor->node->ondisk;
 421
 422                         /* this can assign -1 if the leaf was empty */
 423                         cursor->index = node->count - 1;
 424                         continue;
 425                 } else {
 426                         elm = &node->elms[cursor->index];
 427                         s = hammer_btree_cmp(&cursor->key_beg, &elm->base);
 428                         if (hammer_debug_btree) {
 429                                 kprintf("ELEMENT  %016llx:%d %c %016llx %02x %016llx lo=%02x %d\n",
 430                                         cursor->node->node_offset,
 431                                         cursor->index,
 432                                         (elm[0].leaf.base.btype ?
 433                                          elm[0].leaf.base.btype : '?'),
 434                                         elm[0].leaf.base.obj_id,
 435                                         elm[0].leaf.base.rec_type,
 436                                         elm[0].leaf.base.key,
 437                                         elm[0].leaf.base.localization,
 438                                         s
 439                                 );
 440                         }
 441                         if (s > 0) {
 442                                 error = ENOENT;
 443                                 break;
 444                         }
 445
 446                         switch(elm->leaf.base.btype) {
 447                         case HAMMER_BTREE_TYPE_RECORD:
 448                                 if ((cursor->flags & HAMMER_CURSOR_ASOF) &&
 449                                     hammer_btree_chkts(cursor->asof, &elm->base)) {
 450                                         --cursor->index;
 451                                         continue;
 452                                 }
 453                                 break;
 454                         default:
 455                                 error = EINVAL;
 456                                 break;
 457                         }
 458                         if (error)
 459                                 break;
 460                 }
 461                 /*
 462                  * node pointer invalid after loop
 463                  */
 464
 465                 /*
 466                  * Return entry
 467                  */
 468                 if (hammer_debug_btree) {
 469                         int i = cursor->index;
 470                         hammer_btree_elm_t elm = &cursor->node->ondisk->elms[i];
 471                         kprintf("ITERATE  %p:%d %016llx %02x %016llx lo=%02x\n",
 472                                 cursor->node, i,
 473                                 elm->internal.base.obj_id,
 474                                 elm->internal.base.rec_type,
 475                                 elm->internal.base.key,
 476                                 elm->internal.base.localization
 477                         );
 478                 }
 479                 return(0);
 480         }
 481         return(error);
 482 }
 483
 484 /*
 485  * Lookup cursor->key_beg.  0 is returned on success, ENOENT if the entry
 486  * could not be found, EDEADLK if inserting and a retry is needed, and a
 487  * fatal error otherwise.  When retrying, the caller must terminate the
 488  * cursor and reinitialize it.  EDEADLK cannot be returned if not inserting.
 489  *
 490  * The cursor is suitably positioned for a deletion on success, and suitably
 491  * positioned for an insertion on ENOENT if HAMMER_CURSOR_INSERT was
 492  * specified.
 493  *
 494  * The cursor may begin anywhere, the search will traverse the tree in
 495  * either direction to locate the requested element.
 496  *
 497  * Most of the logic implementing historical searches is handled here.  We
 498  * do an initial lookup with create_tid set to the asof TID.  Due to the
 499  * way records are laid out, a backwards iteration may be required if
 500  * ENOENT is returned to locate the historical record.  Here's the
 501  * problem:
 502  *
 503  * create_tid:    10      15       20
 504  *                   LEAF1   LEAF2
 505  * records:         (11)        (18)
 506  *
 507  * Lets say we want to do a lookup AS-OF timestamp 17.  We will traverse
 508  * LEAF2 but the only record in LEAF2 has a create_tid of 18, which is
 509  * not visible and thus causes ENOENT to be returned.  We really need
 510  * to check record 11 in LEAF1.  If it also fails then the search fails
 511  * (e.g. it might represent the range 11-16 and thus still not match our
 512  * AS-OF timestamp of 17).  Note that LEAF1 could be empty, requiring
 513  * further iterations.
 514  *
 515  * If this case occurs btree_search() will set HAMMER_CURSOR_CREATE_CHECK
 516  * and the cursor->create_check TID if an iteration might be needed.
 517  * In the above example create_check would be set to 14.
 518  */
 519 int
 520 hammer_btree_lookup(hammer_cursor_t cursor)
 521 {
 522         int error;
 523
 524         ++hammer_stats_btree_lookups;
 525         if (cursor->flags & HAMMER_CURSOR_ASOF) {
 526                 KKASSERT((cursor->flags & HAMMER_CURSOR_INSERT) == 0);
 527                 cursor->key_beg.create_tid = cursor->asof;
 528                 for (;;) {
 529                         cursor->flags &= ~HAMMER_CURSOR_CREATE_CHECK;
 530                         error = btree_search(cursor, 0);
 531                         if (error != ENOENT ||
 532                             (cursor->flags & HAMMER_CURSOR_CREATE_CHECK) == 0) {
 533                                 /*
 534                                  * Stop if no error.
 535                                  * Stop if error other then ENOENT.
 536                                  * Stop if ENOENT and not special case.
 537                                  */
 538                                 break;
 539                         }
 540                         if (hammer_debug_btree) {
 541                                 kprintf("CREATE_CHECK %016llx\n",
 542                                         cursor->create_check);
 543                         }
 544                         cursor->key_beg.create_tid = cursor->create_check;
 545                         /* loop */
 546                 }
 547         } else {
 548                 error = btree_search(cursor, 0);
 549         }
 550         if (error == 0)
 551                 error = hammer_btree_extract(cursor, cursor->flags);
 552         return(error);
 553 }
 554
 555 /*
 556  * Execute the logic required to start an iteration.  The first record
 557  * located within the specified range is returned and iteration control
 558  * flags are adjusted for successive hammer_btree_iterate() calls.
 559  */
 560 int
 561 hammer_btree_first(hammer_cursor_t cursor)
 562 {
 563         int error;
 564
 565         error = hammer_btree_lookup(cursor);
 566         if (error == ENOENT) {
 567                 cursor->flags &= ~HAMMER_CURSOR_ATEDISK;
 568                 error = hammer_btree_iterate(cursor);
 569         }
 570         cursor->flags |= HAMMER_CURSOR_ATEDISK;
 571         return(error);
 572 }
 573
 574 /*
 575  * Similarly but for an iteration in the reverse direction.
 576  *
 577  * Set ATEDISK when iterating backwards to skip the current entry,
 578  * which after an ENOENT lookup will be pointing beyond our end point.
 579  */
 580 int
 581 hammer_btree_last(hammer_cursor_t cursor)
 582 {
 583         struct hammer_base_elm save;
 584         int error;
 585
 586         save = cursor->key_beg;
 587         cursor->key_beg = cursor->key_end;
 588         error = hammer_btree_lookup(cursor);
 589         cursor->key_beg = save;
 590         if (error == ENOENT ||
 591             (cursor->flags & HAMMER_CURSOR_END_INCLUSIVE) == 0) {
 592                 cursor->flags |= HAMMER_CURSOR_ATEDISK;
 593                 error = hammer_btree_iterate_reverse(cursor);
 594         }
 595         cursor->flags |= HAMMER_CURSOR_ATEDISK;
 596         return(error);
 597 }
 598
 599 /*
 600  * Extract the record and/or data associated with the cursor's current
 601  * position.  Any prior record or data stored in the cursor is replaced.
 602  * The cursor must be positioned at a leaf node.
 603  *
 604  * NOTE: All extractions occur at the leaf of the B-Tree.
 605  */
 606 int
 607 hammer_btree_extract(hammer_cursor_t cursor, int flags)
 608 {
 609         hammer_mount_t hmp;
 610         hammer_node_ondisk_t node;
 611         hammer_btree_elm_t elm;
 612         hammer_off_t data_off;
 613         int32_t data_len;
 614         int error;
 615
 616         /*
 617          * The case where the data reference resolves to the same buffer
 618          * as the record reference must be handled.
 619          */
 620         node = cursor->node->ondisk;
 621         elm = &node->elms[cursor->index];
 622         cursor->data = NULL;
 623         hmp = cursor->node->hmp;
 624
 625         /*
 626          * There is nothing to extract for an internal element.
 627          */
 628         if (node->type == HAMMER_BTREE_TYPE_INTERNAL)
 629                 return(EINVAL);
 630
 631         /*
 632          * Only record types have data.
 633          */
 634         KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF);
 635         cursor->leaf = &elm->leaf;
 636
 637         if ((flags & HAMMER_CURSOR_GET_DATA) == 0)
 638                 return(0);
 639         if (elm->leaf.base.btype != HAMMER_BTREE_TYPE_RECORD)
 640                 return(0);
 641         data_off = elm->leaf.data_offset;
 642         data_len = elm->leaf.data_len;
 643         if (data_off == 0)
 644                 return(0);
 645
 646         /*
 647          * Load the data
 648          */
 649         KKASSERT(data_len >= 0 && data_len <= HAMMER_XBUFSIZE);
 650         cursor->data = hammer_bread_ext(hmp, data_off, data_len,
 651                                         &error, &cursor->data_buffer);
 652         if (hammer_crc_test_leaf(cursor->data, &elm->leaf) == 0)
 653                 Debugger("CRC FAILED: DATA");
 654         return(error);
 655 }
 656
 657
 658 /*
 659  * Insert a leaf element into the B-Tree at the current cursor position.
 660  * The cursor is positioned such that the element at and beyond the cursor
 661  * are shifted to make room for the new record.
 662  *
 663  * The caller must call hammer_btree_lookup() with the HAMMER_CURSOR_INSERT
 664  * flag set and that call must return ENOENT before this function can be
 665  * called.
 666  *
 667  * The caller may depend on the cursor's exclusive lock after return to
 668  * interlock frontend visibility (see HAMMER_RECF_CONVERT_DELETE).
 669  *
 670  * ENOSPC is returned if there is no room to insert a new record.
 671  */
 672 int
 673 hammer_btree_insert(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm,
 674                     int *doprop)
 675 {
 676         hammer_node_ondisk_t node;
 677         int i;
 678         int error;
 679
 680         *doprop = 0;
 681         if ((error = hammer_cursor_upgrade_node(cursor)) != 0)
 682                 return(error);
 683         ++hammer_stats_btree_inserts;
 684
 685         /*
 686          * Insert the element at the leaf node and update the count in the
 687          * parent.  It is possible for parent to be NULL, indicating that
 688          * the filesystem's ROOT B-Tree node is a leaf itself, which is
 689          * possible.  The root inode can never be deleted so the leaf should
 690          * never be empty.
 691          *
 692          * Remember that the right-hand boundary is not included in the
 693          * count.
 694          */
 695         hammer_modify_node_all(cursor->trans, cursor->node);
 696         node = cursor->node->ondisk;
 697         i = cursor->index;
 698         KKASSERT(elm->base.btype != 0);
 699         KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF);
 700         KKASSERT(node->count < HAMMER_BTREE_LEAF_ELMS);
 701         if (i != node->count) {
 702                 bcopy(&node->elms[i], &node->elms[i+1],
 703                       (node->count - i) * sizeof(*elm));
 704         }
 705         node->elms[i].leaf = *elm;
 706         ++node->count;
 707
 708         /*
 709          * Update the leaf node's aggregate mirror_tid for mirroring
 710          * support.
 711          */
 712         if (node->mirror_tid < elm->base.delete_tid) {
 713                 node->mirror_tid = elm->base.delete_tid;
 714                 *doprop = 1;
 715         }
 716         if (node->mirror_tid < elm->base.create_tid) {
 717                 node->mirror_tid = elm->base.create_tid;
 718                 *doprop = 1;
 719         }
 720         hammer_modify_node_done(cursor->node);
 721
 722         /*
 723          * Debugging sanity checks.
 724          */
 725         KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->base) <= 0);
 726         KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->base) > 0);
 727         if (i) {
 728                 KKASSERT(hammer_btree_cmp(&node->elms[i-1].leaf.base, &elm->base) < 0);
 729         }
 730         if (i != node->count - 1)
 731                 KKASSERT(hammer_btree_cmp(&node->elms[i+1].leaf.base, &elm->base) > 0);
 732
 733         return(0);
 734 }
 735
 736 /*
 737  * Delete a record from the B-Tree at the current cursor position.
 738  * The cursor is positioned such that the current element is the one
 739  * to be deleted.
 740  *
 741  * On return the cursor will be positioned after the deleted element and
 742  * MAY point to an internal node.  It will be suitable for the continuation
 743  * of an iteration but not for an insertion or deletion.
 744  *
 745  * Deletions will attempt to partially rebalance the B-Tree in an upward
 746  * direction, but will terminate rather then deadlock.  Empty internal nodes
 747  * are never allowed by a deletion which deadlocks may end up giving us an
 748  * empty leaf.  The pruner will clean up and rebalance the tree.
 749  *
 750  * This function can return EDEADLK, requiring the caller to retry the
 751  * operation after clearing the deadlock.
 752  */
 753 int
 754 hammer_btree_delete(hammer_cursor_t cursor)
 755 {
 756         hammer_node_ondisk_t ondisk;
 757         hammer_node_t node;
 758         hammer_node_t parent;
 759         int error;
 760         int i;
 761
 762         if ((error = hammer_cursor_upgrade(cursor)) != 0)
 763                 return(error);
 764         ++hammer_stats_btree_deletes;
 765
 766         /*
 767          * Delete the element from the leaf node.
 768          *
 769          * Remember that leaf nodes do not have boundaries.
 770          */
 771         node = cursor->node;
 772         ondisk = node->ondisk;
 773         i = cursor->index;
 774
 775         KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_LEAF);
 776         KKASSERT(i >= 0 && i < ondisk->count);
 777         hammer_modify_node_all(cursor->trans, node);
 778         if (i + 1 != ondisk->count) {
 779                 bcopy(&ondisk->elms[i+1], &ondisk->elms[i],
 780                       (ondisk->count - i - 1) * sizeof(ondisk->elms[0]));
 781         }
 782         --ondisk->count;
 783         hammer_modify_node_done(node);
 784         hammer_cursor_deleted_element(node, i);
 785
 786         /*
 787          * Validate local parent
 788          */
 789         if (ondisk->parent) {
 790                 parent = cursor->parent;
 791
 792                 KKASSERT(parent != NULL);
 793                 KKASSERT(parent->node_offset == ondisk->parent);
 794         }
 795
 796         /*
 797          * If the leaf becomes empty it must be detached from the parent,
 798          * potentially recursing through to the filesystem root.
 799          *
 800          * This may reposition the cursor at one of the parent's of the
 801          * current node.
 802          *
 803          * Ignore deadlock errors, that simply means that btree_remove
 804          * was unable to recurse and had to leave us with an empty leaf.
 805          */
 806         KKASSERT(cursor->index <= ondisk->count);
 807         if (ondisk->count == 0) {
 808                 error = btree_remove(cursor);
 809                 if (error == EDEADLK)
 810                         error = 0;
 811         } else {
 812                 error = 0;
 813         }
 814         KKASSERT(cursor->parent == NULL ||
 815                  cursor->parent_index < cursor->parent->ondisk->count);
 816         return(error);
 817 }
 818
 819 /*
 820  * PRIMAY B-TREE SEARCH SUPPORT PROCEDURE
 821  *
 822  * Search the filesystem B-Tree for cursor->key_beg, return the matching node.
 823  *
 824  * The search can begin ANYWHERE in the B-Tree.  As a first step the search
 825  * iterates up the tree as necessary to properly position itself prior to
 826  * actually doing the sarch.
 827  *
 828  * INSERTIONS: The search will split full nodes and leaves on its way down
 829  * and guarentee that the leaf it ends up on is not full.  If we run out
 830  * of space the search continues to the leaf (to position the cursor for
 831  * the spike), but ENOSPC is returned.
 832  *
 833  * The search is only guarenteed to end up on a leaf if an error code of 0
 834  * is returned, or if inserting and an error code of ENOENT is returned.
 835  * Otherwise it can stop at an internal node.  On success a search returns
 836  * a leaf node.
 837  *
 838  * COMPLEXITY WARNING!  This is the core B-Tree search code for the entire
 839  * filesystem, and it is not simple code.  Please note the following facts:
 840  *
 841  * - Internal node recursions have a boundary on the left AND right.  The
 842  *   right boundary is non-inclusive.  The create_tid is a generic part
 843  *   of the key for internal nodes.
 844  *
 845  * - Leaf nodes contain terminal elements only now.
 846  *
 847  * - Filesystem lookups typically set HAMMER_CURSOR_ASOF, indicating a
 848  *   historical search.  ASOF and INSERT are mutually exclusive.  When
 849  *   doing an as-of lookup btree_search() checks for a right-edge boundary
 850  *   case.  If while recursing down the left-edge differs from the key
 851  *   by ONLY its create_tid, HAMMER_CURSOR_CREATE_CHECK is set along
 852  *   with cursor->create_check.  This is used by btree_lookup() to iterate.
 853  *   The iteration backwards because as-of searches can wind up going
 854  *   down the wrong branch of the B-Tree.
 855  */
 856 static
 857 int
 858 btree_search(hammer_cursor_t cursor, int flags)
 859 {
 860         hammer_node_ondisk_t node;
 861         hammer_btree_elm_t elm;
 862         int error;
 863         int enospc = 0;
 864         int i;
 865         int r;
 866         int s;
 867
 868         flags |= cursor->flags;
 869         ++hammer_stats_btree_searches;
 870
 871         if (hammer_debug_btree) {
 872                 kprintf("SEARCH   %016llx[%d] %016llx %02x key=%016llx cre=%016llx lo=%02x (td = %p)\n",
 873                         cursor->node->node_offset,
 874                         cursor->index,
 875                         cursor->key_beg.obj_id,
 876                         cursor->key_beg.rec_type,
 877                         cursor->key_beg.key,
 878                         cursor->key_beg.create_tid,
 879                         cursor->key_beg.localization,
 880                         curthread
 881                 );
 882                 if (cursor->parent)
 883                     kprintf("SEARCHP %016llx[%d] (%016llx/%016llx %016llx/%016llx) (%p/%p %p/%p)\n",
 884                         cursor->parent->node_offset, cursor->parent_index,
 885                         cursor->left_bound->obj_id,
 886                         cursor->parent->ondisk->elms[cursor->parent_index].internal.base.obj_id,
 887                         cursor->right_bound->obj_id,
 888                         cursor->parent->ondisk->elms[cursor->parent_index+1].internal.base.obj_id,
 889                         cursor->left_bound,
 890                         &cursor->parent->ondisk->elms[cursor->parent_index],
 891                         cursor->right_bound,
 892                         &cursor->parent->ondisk->elms[cursor->parent_index+1]
 893                     );
 894         }
 895
 896         /*
 897          * Move our cursor up the tree until we find a node whos range covers
 898          * the key we are trying to locate.
 899          *
 900          * The left bound is inclusive, the right bound is non-inclusive.
 901          * It is ok to cursor up too far.
 902          */
 903         for (;;) {
 904                 r = hammer_btree_cmp(&cursor->key_beg, cursor->left_bound);
 905                 s = hammer_btree_cmp(&cursor->key_beg, cursor->right_bound);
 906                 if (r >= 0 && s < 0)
 907                         break;
 908                 KKASSERT(cursor->parent);
 909                 ++hammer_stats_btree_iterations;
 910                 error = hammer_cursor_up(cursor);
 911                 if (error)
 912                         goto done;
 913         }
 914
 915         /*
 916          * The delete-checks below are based on node, not parent.  Set the
 917          * initial delete-check based on the parent.
 918          */
 919         if (r == 1) {
 920                 KKASSERT(cursor->left_bound->create_tid != 1);
 921                 cursor->create_check = cursor->left_bound->create_tid - 1;
 922                 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK;
 923         }
 924
 925         /*
 926          * We better have ended up with a node somewhere.
 927          */
 928         KKASSERT(cursor->node != NULL);
 929
 930         /*
 931          * If we are inserting we can't start at a full node if the parent
 932          * is also full (because there is no way to split the node),
 933          * continue running up the tree until the requirement is satisfied
 934          * or we hit the root of the filesystem.
 935          *
 936          * (If inserting we aren't doing an as-of search so we don't have
 937          *  to worry about create_check).
 938          */
 939         while ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) {
 940                 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) {
 941                         if (btree_node_is_full(cursor->node->ondisk) == 0)
 942                                 break;
 943                 } else {
 944                         if (btree_node_is_full(cursor->node->ondisk) ==0)
 945                                 break;
 946                 }
 947                 if (cursor->node->ondisk->parent == 0 ||
 948                     cursor->parent->ondisk->count != HAMMER_BTREE_INT_ELMS) {
 949                         break;
 950                 }
 951                 ++hammer_stats_btree_iterations;
 952                 error = hammer_cursor_up(cursor);
 953                 /* node may have become stale */
 954                 if (error)
 955                         goto done;
 956         }
 957
 958         /*
 959          * Push down through internal nodes to locate the requested key.
 960          */
 961         node = cursor->node->ondisk;
 962         while (node->type == HAMMER_BTREE_TYPE_INTERNAL) {
 963                 /*
 964                  * Scan the node to find the subtree index to push down into.
 965                  * We go one-past, then back-up.
 966                  *
 967                  * We must proactively remove deleted elements which may
 968                  * have been left over from a deadlocked btree_remove().
 969                  *
 970                  * The left and right boundaries are included in the loop
 971                  * in order to detect edge cases.
 972                  *
 973                  * If the separator only differs by create_tid (r == 1)
 974                  * and we are doing an as-of search, we may end up going
 975                  * down a branch to the left of the one containing the
 976                  * desired key.  This requires numerous special cases.
 977                  */
 978                 ++hammer_stats_btree_iterations;
 979                 if (hammer_debug_btree) {
 980                         kprintf("SEARCH-I %016llx count=%d\n",
 981                                 cursor->node->node_offset,
 982                                 node->count);
 983                 }
 984
 985                 /*
 986                  * Try to shortcut the search before dropping into the
 987                  * linear loop.  Locate the first node where r <= 1.
 988                  */
 989                 i = hammer_btree_search_node(&cursor->key_beg, node);
 990                 while (i <= node->count) {
 991                         ++hammer_stats_btree_elements;
 992                         elm = &node->elms[i];
 993                         r = hammer_btree_cmp(&cursor->key_beg, &elm->base);
 994                         if (hammer_debug_btree > 2) {
 995                                 kprintf(" IELM %p %d r=%d\n",
 996                                         &node->elms[i], i, r);
 997                         }
 998                         if (r < 0)
 999                                 break;
1000                         if (r == 1) {
1001                                 KKASSERT(elm->base.create_tid != 1);
1002                                 cursor->create_check = elm->base.create_tid - 1;
1003                                 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK;
1004                         }
1005                         ++i;
1006                 }
1007                 if (hammer_debug_btree) {
1008                         kprintf("SEARCH-I preI=%d/%d r=%d\n",
1009                                 i, node->count, r);
1010                 }
1011
1012                 /*
1013                  * These cases occur when the parent's idea of the boundary
1014                  * is wider then the child's idea of the boundary, and
1015                  * require special handling.  If not inserting we can
1016                  * terminate the search early for these cases but the
1017                  * child's boundaries cannot be unconditionally modified.
1018                  */
1019                 if (i == 0) {
1020                         /*
1021                          * If i == 0 the search terminated to the LEFT of the
1022                          * left_boundary but to the RIGHT of the parent's left
1023                          * boundary.
1024                          */
1025                         u_int8_t save;
1026
1027                         elm = &node->elms[0];
1028
1029                         /*
1030                          * If we aren't inserting we can stop here.
1031                          */
1032                         if ((flags & (HAMMER_CURSOR_INSERT |
1033                                       HAMMER_CURSOR_PRUNING)) == 0) {
1034                                 cursor->index = 0;
1035                                 return(ENOENT);
1036                         }
1037
1038                         /*
1039                          * Correct a left-hand boundary mismatch.
1040                          *
1041                          * We can only do this if we can upgrade the lock,
1042                          * and synchronized as a background cursor (i.e.
1043                          * inserting or pruning).
1044                          *
1045                          * WARNING: We can only do this if inserting, i.e.
1046                          * we are running on the backend.
1047                          */
1048                         if ((error = hammer_cursor_upgrade(cursor)) != 0)
1049                                 return(error);
1050                         KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND);
1051                         hammer_modify_node_field(cursor->trans, cursor->node,
1052                                                  elms[0]);
1053                         save = node->elms[0].base.btype;
1054                         node->elms[0].base = *cursor->left_bound;
1055                         node->elms[0].base.btype = save;
1056                         hammer_modify_node_done(cursor->node);
1057                 } else if (i == node->count + 1) {
1058                         /*
1059                          * If i == node->count + 1 the search terminated to
1060                          * the RIGHT of the right boundary but to the LEFT
1061                          * of the parent's right boundary.  If we aren't
1062                          * inserting we can stop here.
1063                          *
1064                          * Note that the last element in this case is
1065                          * elms[i-2] prior to adjustments to 'i'.
1066                          */
1067                         --i;
1068                         if ((flags & (HAMMER_CURSOR_INSERT |
1069                                       HAMMER_CURSOR_PRUNING)) == 0) {
1070                                 cursor->index = i;
1071                                 return (ENOENT);
1072                         }
1073
1074                         /*
1075                          * Correct a right-hand boundary mismatch.
1076                          * (actual push-down record is i-2 prior to
1077                          * adjustments to i).
1078                          *
1079                          * We can only do this if we can upgrade the lock,
1080                          * and synchronized as a background cursor (i.e.
1081                          * inserting or pruning).
1082                          *
1083                          * WARNING: We can only do this if inserting, i.e.
1084                          * we are running on the backend.
1085                          */
1086                         if ((error = hammer_cursor_upgrade(cursor)) != 0)
1087                                 return(error);
1088                         elm = &node->elms[i];
1089                         KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND);
1090                         hammer_modify_node(cursor->trans, cursor->node,
1091                                            &elm->base, sizeof(elm->base));
1092                         elm->base = *cursor->right_bound;
1093                         hammer_modify_node_done(cursor->node);
1094                         --i;
1095                 } else {
1096                         /*
1097                          * The push-down index is now i - 1.  If we had
1098                          * terminated on the right boundary this will point
1099                          * us at the last element.
1100                          */
1101                         --i;
1102                 }
1103                 cursor->index = i;
1104                 elm = &node->elms[i];
1105
1106                 if (hammer_debug_btree) {
1107                         kprintf("RESULT-I %016llx[%d] %016llx %02x "
1108                                 "key=%016llx cre=%016llx lo=%02x\n",
1109                                 cursor->node->node_offset,
1110                                 i,
1111                                 elm->internal.base.obj_id,
1112                                 elm->internal.base.rec_type,
1113                                 elm->internal.base.key,
1114                                 elm->internal.base.create_tid,
1115                                 elm->internal.base.localization
1116                         );
1117                 }
1118
1119                 /*
1120                  * We better have a valid subtree offset.
1121                  */
1122                 KKASSERT(elm->internal.subtree_offset != 0);
1123
1124                 /*
1125                  * Handle insertion and deletion requirements.
1126                  *
1127                  * If inserting split full nodes.  The split code will
1128                  * adjust cursor->node and cursor->index if the current
1129                  * index winds up in the new node.
1130                  *
1131                  * If inserting and a left or right edge case was detected,
1132                  * we cannot correct the left or right boundary and must
1133                  * prepend and append an empty leaf node in order to make
1134                  * the boundary correction.
1135                  *
1136                  * If we run out of space we set enospc and continue on
1137                  * to a leaf to provide the spike code with a good point
1138                  * of entry.
1139                  */
1140                 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) {
1141                         if (btree_node_is_full(node)) {
1142                                 error = btree_split_internal(cursor);
1143                                 if (error) {
1144                                         if (error != ENOSPC)
1145                                                 goto done;
1146                                         enospc = 1;
1147                                 }
1148                                 /*
1149                                  * reload stale pointers
1150                                  */
1151                                 i = cursor->index;
1152                                 node = cursor->node->ondisk;
1153                         }
1154                 }
1155
1156                 /*
1157                  * Push down (push into new node, existing node becomes
1158                  * the parent) and continue the search.
1159                  */
1160                 error = hammer_cursor_down(cursor);
1161                 /* node may have become stale */
1162                 if (error)
1163                         goto done;
1164                 node = cursor->node->ondisk;
1165         }
1166
1167         /*
1168          * We are at a leaf, do a linear search of the key array.
1169          *
1170          * On success the index is set to the matching element and 0
1171          * is returned.
1172          *
1173          * On failure the index is set to the insertion point and ENOENT
1174          * is returned.
1175          *
1176          * Boundaries are not stored in leaf nodes, so the index can wind
1177          * up to the left of element 0 (index == 0) or past the end of
1178          * the array (index == node->count).  It is also possible that the
1179          * leaf might be empty.
1180          */
1181         ++hammer_stats_btree_iterations;
1182         KKASSERT (node->type == HAMMER_BTREE_TYPE_LEAF);
1183         KKASSERT(node->count <= HAMMER_BTREE_LEAF_ELMS);
1184         if (hammer_debug_btree) {
1185                 kprintf("SEARCH-L %016llx count=%d\n",
1186                         cursor->node->node_offset,
1187                         node->count);
1188         }
1189
1190         /*
1191          * Try to shortcut the search before dropping into the
1192          * linear loop.  Locate the first node where r <= 1.
1193          */
1194         i = hammer_btree_search_node(&cursor->key_beg, node);
1195         while (i < node->count) {
1196                 ++hammer_stats_btree_elements;
1197                 elm = &node->elms[i];
1198
1199                 r = hammer_btree_cmp(&cursor->key_beg, &elm->leaf.base);
1200
1201                 if (hammer_debug_btree > 1)
1202                         kprintf("  ELM %p %d r=%d\n", &node->elms[i], i, r);
1203
1204                 /*
1205                  * We are at a record element.  Stop if we've flipped past
1206                  * key_beg, not counting the create_tid test.  Allow the
1207                  * r == 1 case (key_beg > element but differs only by its
1208                  * create_tid) to fall through to the AS-OF check.
1209                  */
1210                 KKASSERT (elm->leaf.base.btype == HAMMER_BTREE_TYPE_RECORD);
1211
1212                 if (r < 0)
1213                         goto failed;
1214                 if (r > 1) {
1215                         ++i;
1216                         continue;
1217                 }
1218
1219                 /*
1220                  * Check our as-of timestamp against the element.
1221                  */
1222                 if (flags & HAMMER_CURSOR_ASOF) {
1223                         if (hammer_btree_chkts(cursor->asof,
1224                                                &node->elms[i].base) != 0) {
1225                                 ++i;
1226                                 continue;
1227                         }
1228                         /* success */
1229                 } else {
1230                         if (r > 0) {    /* can only be +1 */
1231                                 ++i;
1232                                 continue;
1233                         }
1234                         /* success */
1235                 }
1236                 cursor->index = i;
1237                 error = 0;
1238                 if (hammer_debug_btree) {
1239                         kprintf("RESULT-L %016llx[%d] (SUCCESS)\n",
1240                                 cursor->node->node_offset, i);
1241                 }
1242                 goto done;
1243         }
1244
1245         /*
1246          * The search of the leaf node failed.  i is the insertion point.
1247          */
1248 failed:
1249         if (hammer_debug_btree) {
1250                 kprintf("RESULT-L %016llx[%d] (FAILED)\n",
1251                         cursor->node->node_offset, i);
1252         }
1253
1254         /*
1255          * No exact match was found, i is now at the insertion point.
1256          *
1257          * If inserting split a full leaf before returning.  This
1258          * may have the side effect of adjusting cursor->node and
1259          * cursor->index.
1260          */
1261         cursor->index = i;
1262         if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0 &&
1263              btree_node_is_full(node)) {
1264                 error = btree_split_leaf(cursor);
1265                 if (error) {
1266                         if (error != ENOSPC)
1267                                 goto done;
1268                         enospc = 1;
1269                 }
1270                 /*
1271                  * reload stale pointers
1272                  */
1273                 /* NOT USED
1274                 i = cursor->index;
1275                 node = &cursor->node->internal;
1276                 */
1277         }
1278
1279         /*
1280          * We reached a leaf but did not find the key we were looking for.
1281          * If this is an insert we will be properly positioned for an insert
1282          * (ENOENT) or spike (ENOSPC) operation.
1283          */
1284         error = enospc ? ENOSPC : ENOENT;
1285 done:
1286         return(error);
1287 }
1288
1289 /*
1290  * Heuristical search for the first element whos comparison is <= 1.  May
1291  * return an index whos compare result is > 1 but may only return an index
1292  * whos compare result is <= 1 if it is the first element with that result.
1293  */
1294 int
1295 hammer_btree_search_node(hammer_base_elm_t elm, hammer_node_ondisk_t node)
1296 {
1297         int b;
1298         int s;
1299         int i;
1300         int r;
1301
1302         /*
1303          * Don't bother if the node does not have very many elements
1304          */
1305         b = 0;
1306         s = node->count;
1307         while (s - b > 4) {
1308                 i = b + (s - b) / 2;
1309                 ++hammer_stats_btree_elements;
1310                 r = hammer_btree_cmp(elm, &node->elms[i].leaf.base);
1311                 if (r <= 1) {
1312                         s = i;
1313                 } else {
1314                         b = i;
1315                 }
1316         }
1317         return(b);
1318 }
1319
1320
1321 /************************************************************************
1322  *                         SPLITTING AND MERGING                        *
1323  ************************************************************************
1324  *
1325  * These routines do all the dirty work required to split and merge nodes.
1326  */
1327
1328 /*
1329  * Split an internal node into two nodes and move the separator at the split
1330  * point to the parent.
1331  *
1332  * (cursor->node, cursor->index) indicates the element the caller intends
1333  * to push into.  We will adjust node and index if that element winds
1334  * up in the split node.
1335  *
1336  * If we are at the root of the filesystem a new root must be created with
1337  * two elements, one pointing to the original root and one pointing to the
1338  * newly allocated split node.
1339  */
1340 static
1341 int
1342 btree_split_internal(hammer_cursor_t cursor)
1343 {
1344         hammer_node_ondisk_t ondisk;
1345         hammer_node_t node;
1346         hammer_node_t parent;
1347         hammer_node_t new_node;
1348         hammer_btree_elm_t elm;
1349         hammer_btree_elm_t parent_elm;
1350         hammer_node_locklist_t locklist = NULL;
1351         hammer_mount_t hmp = cursor->trans->hmp;
1352         int parent_index;
1353         int made_root;
1354         int split;
1355         int error;
1356         int i;
1357         const int esize = sizeof(*elm);
1358
1359         error = hammer_btree_lock_children(cursor, &locklist);
1360         if (error)
1361                 goto done;
1362         if ((error = hammer_cursor_upgrade(cursor)) != 0)
1363                 goto done;
1364         ++hammer_stats_btree_splits;
1365
1366         /*
1367          * We are splitting but elms[split] will be promoted to the parent,
1368          * leaving the right hand node with one less element.  If the
1369          * insertion point will be on the left-hand side adjust the split
1370          * point to give the right hand side one additional node.
1371          */
1372         node = cursor->node;
1373         ondisk = node->ondisk;
1374         split = (ondisk->count + 1) / 2;
1375         if (cursor->index <= split)
1376                 --split;
1377
1378         /*
1379          * If we are at the root of the filesystem, create a new root node
1380          * with 1 element and split normally.  Avoid making major
1381          * modifications until we know the whole operation will work.
1382          */
1383         if (ondisk->parent == 0) {
1384                 parent = hammer_alloc_btree(cursor->trans, &error);
1385                 if (parent == NULL)
1386                         goto done;
1387                 hammer_lock_ex(&parent->lock);
1388                 hammer_modify_node_noundo(cursor->trans, parent);
1389                 ondisk = parent->ondisk;
1390                 ondisk->count = 1;
1391                 ondisk->parent = 0;
1392                 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL;
1393                 ondisk->elms[0].base = hmp->root_btree_beg;
1394                 ondisk->elms[0].base.btype = node->ondisk->type;
1395                 ondisk->elms[0].internal.subtree_offset = node->node_offset;
1396                 ondisk->elms[1].base = hmp->root_btree_end;
1397                 hammer_modify_node_done(parent);
1398                 /* ondisk->elms[1].base.btype - not used */
1399                 made_root = 1;
1400                 parent_index = 0;       /* index of current node in parent */
1401         } else {
1402                 made_root = 0;
1403                 parent = cursor->parent;
1404                 parent_index = cursor->parent_index;
1405         }
1406
1407         /*
1408          * Split node into new_node at the split point.
1409          *
1410          *  B O O O P N N B     <-- P = node->elms[split]
1411          *   0 1 2 3 4 5 6      <-- subtree indices
1412          *
1413          *       x x P x x
1414          *        s S S s
1415          *         /   \
1416          *  B O O O B    B N N B        <--- inner boundary points are 'P'
1417          *   0 1 2 3      4 5 6
1418          *
1419          */
1420         new_node = hammer_alloc_btree(cursor->trans, &error);
1421         if (new_node == NULL) {
1422                 if (made_root) {
1423                         hammer_unlock(&parent->lock);
1424                         hammer_delete_node(cursor->trans, parent);
1425                         hammer_rel_node(parent);
1426                 }
1427                 goto done;
1428         }
1429         hammer_lock_ex(&new_node->lock);
1430
1431         /*
1432          * Create the new node.  P becomes the left-hand boundary in the
1433          * new node.  Copy the right-hand boundary as well.
1434          *
1435          * elm is the new separator.
1436          */
1437         hammer_modify_node_noundo(cursor->trans, new_node);
1438         hammer_modify_node_all(cursor->trans, node);
1439         ondisk = node->ondisk;
1440         elm = &ondisk->elms[split];
1441         bcopy(elm, &new_node->ondisk->elms[0],
1442               (ondisk->count - split + 1) * esize);
1443         new_node->ondisk->count = ondisk->count - split;
1444         new_node->ondisk->parent = parent->node_offset;
1445         new_node->ondisk->type = HAMMER_BTREE_TYPE_INTERNAL;
1446         KKASSERT(ondisk->type == new_node->ondisk->type);
1447         hammer_cursor_split_node(node, new_node, split);
1448
1449         /*
1450          * Cleanup the original node.  Elm (P) becomes the new boundary,
1451          * its subtree_offset was moved to the new node.  If we had created
1452          * a new root its parent pointer may have changed.
1453          */
1454         elm->internal.subtree_offset = 0;
1455         ondisk->count = split;
1456
1457         /*
1458          * Insert the separator into the parent, fixup the parent's
1459          * reference to the original node, and reference the new node.
1460          * The separator is P.
1461          *
1462          * Remember that base.count does not include the right-hand boundary.
1463          */
1464         hammer_modify_node_all(cursor->trans, parent);
1465         ondisk = parent->ondisk;
1466         KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS);
1467         parent_elm = &ondisk->elms[parent_index+1];
1468         bcopy(parent_elm, parent_elm + 1,
1469               (ondisk->count - parent_index) * esize);
1470         parent_elm->internal.base = elm->base;  /* separator P */
1471         parent_elm->internal.base.btype = new_node->ondisk->type;
1472         parent_elm->internal.subtree_offset = new_node->node_offset;
1473         ++ondisk->count;
1474         hammer_modify_node_done(parent);
1475         hammer_cursor_inserted_element(parent, parent_index + 1);
1476
1477         /*
1478          * The children of new_node need their parent pointer set to new_node.
1479          * The children have already been locked by
1480          * hammer_btree_lock_children().
1481          */
1482         for (i = 0; i < new_node->ondisk->count; ++i) {
1483                 elm = &new_node->ondisk->elms[i];
1484                 error = btree_set_parent(cursor->trans, new_node, elm);
1485                 if (error) {
1486                         panic("btree_split_internal: btree-fixup problem");
1487                 }
1488         }
1489         hammer_modify_node_done(new_node);
1490
1491         /*
1492          * The filesystem's root B-Tree pointer may have to be updated.
1493          */
1494         if (made_root) {
1495                 hammer_volume_t volume;
1496
1497                 volume = hammer_get_root_volume(hmp, &error);
1498                 KKASSERT(error == 0);
1499
1500                 hammer_modify_volume_field(cursor->trans, volume,
1501                                            vol0_btree_root);
1502                 volume->ondisk->vol0_btree_root = parent->node_offset;
1503                 hammer_modify_volume_done(volume);
1504                 node->ondisk->parent = parent->node_offset;
1505                 if (cursor->parent) {
1506                         hammer_unlock(&cursor->parent->lock);
1507                         hammer_rel_node(cursor->parent);
1508                 }
1509                 cursor->parent = parent;        /* lock'd and ref'd */
1510                 hammer_rel_volume(volume, 0);
1511         }
1512         hammer_modify_node_done(node);
1513
1514         /*
1515          * Ok, now adjust the cursor depending on which element the original
1516          * index was pointing at.  If we are >= the split point the push node
1517          * is now in the new node.
1518          *
1519          * NOTE: If we are at the split point itself we cannot stay with the
1520          * original node because the push index will point at the right-hand
1521          * boundary, which is illegal.
1522          *
1523          * NOTE: The cursor's parent or parent_index must be adjusted for
1524          * the case where a new parent (new root) was created, and the case
1525          * where the cursor is now pointing at the split node.
1526          */
1527         if (cursor->index >= split) {
1528                 cursor->parent_index = parent_index + 1;
1529                 cursor->index -= split;
1530                 hammer_unlock(&cursor->node->lock);
1531                 hammer_rel_node(cursor->node);
1532                 cursor->node = new_node;        /* locked and ref'd */
1533         } else {
1534                 cursor->parent_index = parent_index;
1535                 hammer_unlock(&new_node->lock);
1536                 hammer_rel_node(new_node);
1537         }
1538
1539         /*
1540          * Fixup left and right bounds
1541          */
1542         parent_elm = &parent->ondisk->elms[cursor->parent_index];
1543         cursor->left_bound = &parent_elm[0].internal.base;
1544         cursor->right_bound = &parent_elm[1].internal.base;
1545         KKASSERT(hammer_btree_cmp(cursor->left_bound,
1546                  &cursor->node->ondisk->elms[0].internal.base) <= 0);
1547         KKASSERT(hammer_btree_cmp(cursor->right_bound,
1548                  &cursor->node->ondisk->elms[cursor->node->ondisk->count].internal.base) >= 0);
1549
1550 done:
1551         hammer_btree_unlock_children(&locklist);
1552         hammer_cursor_downgrade(cursor);
1553         return (error);
1554 }
1555
1556 /*
1557  * Same as the above, but splits a full leaf node.
1558  *
1559  * This function
1560  */
1561 static
1562 int
1563 btree_split_leaf(hammer_cursor_t cursor)
1564 {
1565         hammer_node_ondisk_t ondisk;
1566         hammer_node_t parent;
1567         hammer_node_t leaf;
1568         hammer_mount_t hmp;
1569         hammer_node_t new_leaf;
1570         hammer_btree_elm_t elm;
1571         hammer_btree_elm_t parent_elm;
1572         hammer_base_elm_t mid_boundary;
1573         int parent_index;
1574         int made_root;
1575         int split;
1576         int error;
1577         const size_t esize = sizeof(*elm);
1578
1579         if ((error = hammer_cursor_upgrade(cursor)) != 0)
1580                 return(error);
1581         ++hammer_stats_btree_splits;
1582
1583         KKASSERT(hammer_btree_cmp(cursor->left_bound,
1584                  &cursor->node->ondisk->elms[0].leaf.base) <= 0);
1585         KKASSERT(hammer_btree_cmp(cursor->right_bound,
1586                  &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0);
1587
1588         /*
1589          * Calculate the split point.  If the insertion point will be on
1590          * the left-hand side adjust the split point to give the right
1591          * hand side one additional node.
1592          *
1593          * Spikes are made up of two leaf elements which cannot be
1594          * safely split.
1595          */
1596         leaf = cursor->node;
1597         ondisk = leaf->ondisk;
1598         split = (ondisk->count + 1) / 2;
1599         if (cursor->index <= split)
1600                 --split;
1601         error = 0;
1602         hmp = leaf->hmp;
1603
1604         elm = &ondisk->elms[split];
1605
1606         KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm[-1].leaf.base) <= 0);
1607         KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->leaf.base) <= 0);
1608         KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->leaf.base) > 0);
1609         KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm[1].leaf.base) > 0);
1610
1611         /*
1612          * If we are at the root of the tree, create a new root node with
1613          * 1 element and split normally.  Avoid making major modifications
1614          * until we know the whole operation will work.
1615          */
1616         if (ondisk->parent == 0) {
1617                 parent = hammer_alloc_btree(cursor->trans, &error);
1618                 if (parent == NULL)
1619                         goto done;
1620                 hammer_lock_ex(&parent->lock);
1621                 hammer_modify_node_noundo(cursor->trans, parent);
1622                 ondisk = parent->ondisk;
1623                 ondisk->count = 1;
1624                 ondisk->parent = 0;
1625                 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL;
1626                 ondisk->elms[0].base = hmp->root_btree_beg;
1627                 ondisk->elms[0].base.btype = leaf->ondisk->type;
1628                 ondisk->elms[0].internal.subtree_offset = leaf->node_offset;
1629                 ondisk->elms[1].base = hmp->root_btree_end;
1630                 /* ondisk->elms[1].base.btype = not used */
1631                 hammer_modify_node_done(parent);
1632                 made_root = 1;
1633                 parent_index = 0;       /* insertion point in parent */
1634         } else {
1635                 made_root = 0;
1636                 parent = cursor->parent;
1637                 parent_index = cursor->parent_index;
1638         }
1639
1640         /*
1641          * Split leaf into new_leaf at the split point.  Select a separator
1642          * value in-between the two leafs but with a bent towards the right
1643          * leaf since comparisons use an 'elm >= separator' inequality.
1644          *
1645          *  L L L L L L L L
1646          *
1647          *       x x P x x
1648          *        s S S s
1649          *         /   \
1650          *  L L L L     L L L L
1651          */
1652         new_leaf = hammer_alloc_btree(cursor->trans, &error);
1653         if (new_leaf == NULL) {
1654                 if (made_root) {
1655                         hammer_unlock(&parent->lock);
1656                         hammer_delete_node(cursor->trans, parent);
1657                         hammer_rel_node(parent);
1658                 }
1659                 goto done;
1660         }
1661         hammer_lock_ex(&new_leaf->lock);
1662
1663         /*
1664          * Create the new node and copy the leaf elements from the split
1665          * point on to the new node.
1666          */
1667         hammer_modify_node_all(cursor->trans, leaf);
1668         hammer_modify_node_noundo(cursor->trans, new_leaf);
1669         ondisk = leaf->ondisk;
1670         elm = &ondisk->elms[split];
1671         bcopy(elm, &new_leaf->ondisk->elms[0], (ondisk->count - split) * esize);
1672         new_leaf->ondisk->count = ondisk->count - split;
1673         new_leaf->ondisk->parent = parent->node_offset;
1674         new_leaf->ondisk->type = HAMMER_BTREE_TYPE_LEAF;
1675         KKASSERT(ondisk->type == new_leaf->ondisk->type);
1676         hammer_modify_node_done(new_leaf);
1677         hammer_cursor_split_node(leaf, new_leaf, split);
1678
1679         /*
1680          * Cleanup the original node.  Because this is a leaf node and
1681          * leaf nodes do not have a right-hand boundary, there
1682          * aren't any special edge cases to clean up.  We just fixup the
1683          * count.
1684          */
1685         ondisk->count = split;
1686
1687         /*
1688          * Insert the separator into the parent, fixup the parent's
1689          * reference to the original node, and reference the new node.
1690          * The separator is P.
1691          *
1692          * Remember that base.count does not include the right-hand boundary.
1693          * We are copying parent_index+1 to parent_index+2, not +0 to +1.
1694          */
1695         hammer_modify_node_all(cursor->trans, parent);
1696         ondisk = parent->ondisk;
1697         KKASSERT(split != 0);
1698         KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS);
1699         parent_elm = &ondisk->elms[parent_index+1];
1700         bcopy(parent_elm, parent_elm + 1,
1701               (ondisk->count - parent_index) * esize);
1702
1703         hammer_make_separator(&elm[-1].base, &elm[0].base, &parent_elm->base);
1704         parent_elm->internal.base.btype = new_leaf->ondisk->type;
1705         parent_elm->internal.subtree_offset = new_leaf->node_offset;
1706         mid_boundary = &parent_elm->base;
1707         ++ondisk->count;
1708         hammer_modify_node_done(parent);
1709         hammer_cursor_inserted_element(parent, parent_index + 1);
1710
1711         /*
1712          * The filesystem's root B-Tree pointer may have to be updated.
1713          */
1714         if (made_root) {
1715                 hammer_volume_t volume;
1716
1717                 volume = hammer_get_root_volume(hmp, &error);
1718                 KKASSERT(error == 0);
1719
1720                 hammer_modify_volume_field(cursor->trans, volume,
1721                                            vol0_btree_root);
1722                 volume->ondisk->vol0_btree_root = parent->node_offset;
1723                 hammer_modify_volume_done(volume);
1724                 leaf->ondisk->parent = parent->node_offset;
1725                 if (cursor->parent) {
1726                         hammer_unlock(&cursor->parent->lock);
1727                         hammer_rel_node(cursor->parent);
1728                 }
1729                 cursor->parent = parent;        /* lock'd and ref'd */
1730                 hammer_rel_volume(volume, 0);
1731         }
1732         hammer_modify_node_done(leaf);
1733
1734         /*
1735          * Ok, now adjust the cursor depending on which element the original
1736          * index was pointing at.  If we are >= the split point the push node
1737          * is now in the new node.
1738          *
1739          * NOTE: If we are at the split point itself we need to select the
1740          * old or new node based on where key_beg's insertion point will be.
1741          * If we pick the wrong side the inserted element will wind up in
1742          * the wrong leaf node and outside that node's bounds.
1743          */
1744         if (cursor->index > split ||
1745             (cursor->index == split &&
1746              hammer_btree_cmp(&cursor->key_beg, mid_boundary) >= 0)) {
1747                 cursor->parent_index = parent_index + 1;
1748                 cursor->index -= split;
1749                 hammer_unlock(&cursor->node->lock);
1750                 hammer_rel_node(cursor->node);
1751                 cursor->node = new_leaf;
1752         } else {
1753                 cursor->parent_index = parent_index;
1754                 hammer_unlock(&new_leaf->lock);
1755                 hammer_rel_node(new_leaf);
1756         }
1757
1758         /*
1759          * Fixup left and right bounds
1760          */
1761         parent_elm = &parent->ondisk->elms[cursor->parent_index];
1762         cursor->left_bound = &parent_elm[0].internal.base;
1763         cursor->right_bound = &parent_elm[1].internal.base;
1764
1765         /*
1766          * Assert that the bounds are correct.
1767          */
1768         KKASSERT(hammer_btree_cmp(cursor->left_bound,
1769                  &cursor->node->ondisk->elms[0].leaf.base) <= 0);
1770         KKASSERT(hammer_btree_cmp(cursor->right_bound,
1771                  &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0);
1772         KKASSERT(hammer_btree_cmp(cursor->left_bound, &cursor->key_beg) <= 0);
1773         KKASSERT(hammer_btree_cmp(cursor->right_bound, &cursor->key_beg) > 0);
1774
1775 done:
1776         hammer_cursor_downgrade(cursor);
1777         return (error);
1778 }
1779
1780 /*
1781  * Recursively correct the right-hand boundary's create_tid to (tid) as
1782  * long as the rest of the key matches.  We have to recurse upward in
1783  * the tree as well as down the left side of each parent's right node.
1784  *
1785  * Return EDEADLK if we were only partially successful, forcing the caller
1786  * to try again.  The original cursor is not modified.  This routine can
1787  * also fail with EDEADLK if it is forced to throw away a portion of its
1788  * record history.
1789  *
1790  * The caller must pass a downgraded cursor to us (otherwise we can't dup it).
1791  */
1792 struct hammer_rhb {
1793         TAILQ_ENTRY(hammer_rhb) entry;
1794         hammer_node_t   node;
1795         int             index;
1796 };
1797
1798 TAILQ_HEAD(hammer_rhb_list, hammer_rhb);
1799
1800 int
1801 hammer_btree_correct_rhb(hammer_cursor_t cursor, hammer_tid_t tid)
1802 {
1803         struct hammer_rhb_list rhb_list;
1804         hammer_base_elm_t elm;
1805         hammer_node_t orig_node;
1806         struct hammer_rhb *rhb;
1807         int orig_index;
1808         int error;
1809
1810         TAILQ_INIT(&rhb_list);
1811
1812         /*
1813          * Save our position so we can restore it on return.  This also
1814          * gives us a stable 'elm'.
1815          */
1816         orig_node = cursor->node;
1817         hammer_ref_node(orig_node);
1818         hammer_lock_sh(&orig_node->lock);
1819         orig_index = cursor->index;
1820         elm = &orig_node->ondisk->elms[orig_index].base;
1821
1822         /*
1823          * Now build a list of parents going up, allocating a rhb
1824          * structure for each one.
1825          */
1826         while (cursor->parent) {
1827                 /*
1828                  * Stop if we no longer have any right-bounds to fix up
1829                  */
1830                 if (elm->obj_id != cursor->right_bound->obj_id ||
1831                     elm->rec_type != cursor->right_bound->rec_type ||
1832                     elm->key != cursor->right_bound->key) {
1833                         break;
1834                 }
1835
1836                 /*
1837                  * Stop if the right-hand bound's create_tid does not
1838                  * need to be corrected.
1839                  */
1840                 if (cursor->right_bound->create_tid >= tid)
1841                         break;
1842
1843                 rhb = kmalloc(sizeof(*rhb), M_HAMMER, M_WAITOK|M_ZERO);
1844                 rhb->node = cursor->parent;
1845                 rhb->index = cursor->parent_index;
1846                 hammer_ref_node(rhb->node);
1847                 hammer_lock_sh(&rhb->node->lock);
1848                 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry);
1849
1850                 hammer_cursor_up(cursor);
1851         }
1852
1853         /*
1854          * now safely adjust the right hand bound for each rhb.  This may
1855          * also require taking the right side of the tree and iterating down
1856          * ITS left side.
1857          */
1858         error = 0;
1859         while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) {
1860                 error = hammer_cursor_seek(cursor, rhb->node, rhb->index);
1861                 if (error)
1862                         break;
1863                 TAILQ_REMOVE(&rhb_list, rhb, entry);
1864                 hammer_unlock(&rhb->node->lock);
1865                 hammer_rel_node(rhb->node);
1866                 kfree(rhb, M_HAMMER);
1867
1868                 switch (cursor->node->ondisk->type) {
1869                 case HAMMER_BTREE_TYPE_INTERNAL:
1870                         /*
1871                          * Right-boundary for parent at internal node
1872                          * is one element to the right of the element whos
1873                          * right boundary needs adjusting.  We must then
1874                          * traverse down the left side correcting any left
1875                          * bounds (which may now be too far to the left).
1876                          */
1877                         ++cursor->index;
1878                         error = hammer_btree_correct_lhb(cursor, tid);
1879                         break;
1880                 default:
1881                         panic("hammer_btree_correct_rhb(): Bad node type");
1882                         error = EINVAL;
1883                         break;
1884                 }
1885         }
1886
1887         /*
1888          * Cleanup
1889          */
1890         while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) {
1891                 TAILQ_REMOVE(&rhb_list, rhb, entry);
1892                 hammer_unlock(&rhb->node->lock);
1893                 hammer_rel_node(rhb->node);
1894                 kfree(rhb, M_HAMMER);
1895         }
1896         error = hammer_cursor_seek(cursor, orig_node, orig_index);
1897         hammer_unlock(&orig_node->lock);
1898         hammer_rel_node(orig_node);
1899         return (error);
1900 }
1901
1902 /*
1903  * Similar to rhb (in fact, rhb calls lhb), but corrects the left hand
1904  * bound going downward starting at the current cursor position.
1905  *
1906  * This function does not restore the cursor after use.
1907  */
1908 int
1909 hammer_btree_correct_lhb(hammer_cursor_t cursor, hammer_tid_t tid)
1910 {
1911         struct hammer_rhb_list rhb_list;
1912         hammer_base_elm_t elm;
1913         hammer_base_elm_t cmp;
1914         struct hammer_rhb *rhb;
1915         int error;
1916
1917         TAILQ_INIT(&rhb_list);
1918
1919         cmp = &cursor->node->ondisk->elms[cursor->index].base;
1920
1921         /*
1922          * Record the node and traverse down the left-hand side for all
1923          * matching records needing a boundary correction.
1924          */
1925         error = 0;
1926         for (;;) {
1927                 rhb = kmalloc(sizeof(*rhb), M_HAMMER, M_WAITOK|M_ZERO);
1928                 rhb->node = cursor->node;
1929                 rhb->index = cursor->index;
1930                 hammer_ref_node(rhb->node);
1931                 hammer_lock_sh(&rhb->node->lock);
1932                 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry);
1933
1934                 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) {
1935                         /*
1936                          * Nothing to traverse down if we are at the right
1937                          * boundary of an internal node.
1938                          */
1939                         if (cursor->index == cursor->node->ondisk->count)
1940                                 break;
1941                 } else {
1942                         elm = &cursor->node->ondisk->elms[cursor->index].base;
1943                         if (elm->btype == HAMMER_BTREE_TYPE_RECORD)
1944                                 break;
1945                         panic("Illegal leaf record type %02x", elm->btype);
1946                 }
1947                 error = hammer_cursor_down(cursor);
1948                 if (error)
1949                         break;
1950
1951                 elm = &cursor->node->ondisk->elms[cursor->index].base;
1952                 if (elm->obj_id != cmp->obj_id ||
1953                     elm->rec_type != cmp->rec_type ||
1954                     elm->key != cmp->key) {
1955                         break;
1956                 }
1957                 if (elm->create_tid >= tid)
1958                         break;
1959
1960         }
1961
1962         /*
1963          * Now we can safely adjust the left-hand boundary from the bottom-up.
1964          * The last element we remove from the list is the caller's right hand
1965          * boundary, which must also be adjusted.
1966          */
1967         while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) {
1968                 error = hammer_cursor_seek(cursor, rhb->node, rhb->index);
1969                 if (error)
1970                         break;
1971                 TAILQ_REMOVE(&rhb_list, rhb, entry);
1972                 hammer_unlock(&rhb->node->lock);
1973                 hammer_rel_node(rhb->node);
1974                 kfree(rhb, M_HAMMER);
1975
1976                 elm = &cursor->node->ondisk->elms[cursor->index].base;
1977                 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) {
1978                         hammer_modify_node(cursor->trans, cursor->node,
1979                                            &elm->create_tid,
1980                                            sizeof(elm->create_tid));
1981                         elm->create_tid = tid;
1982                         hammer_modify_node_done(cursor->node);
1983                 } else {
1984                         panic("hammer_btree_correct_lhb(): Bad element type");
1985                 }
1986         }
1987
1988         /*
1989          * Cleanup
1990          */
1991         while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) {
1992                 TAILQ_REMOVE(&rhb_list, rhb, entry);
1993                 hammer_unlock(&rhb->node->lock);
1994                 hammer_rel_node(rhb->node);
1995                 kfree(rhb, M_HAMMER);
1996         }
1997         return (error);
1998 }
1999
2000 /*
2001  * Attempt to remove the locked, empty or want-to-be-empty B-Tree node at
2002  * (cursor->node).  Returns 0 on success, EDEADLK if we could not complete
2003  * the operation due to a deadlock, or some other error.
2004  *
2005  * This routine is always called with an empty, locked leaf but may recurse
2006  * into want-to-be-empty parents as part of its operation.
2007  *
2008  * It should also be noted that when removing empty leaves we must be sure
2009  * to test and update mirror_tid because another thread may have deadlocked
2010  * against us (or someone) trying to propagate it up and cannot retry once
2011  * the node has been deleted.
2012  *
2013  * On return the cursor may end up pointing to an internal node, suitable
2014  * for further iteration but not for an immediate insertion or deletion.
2015  */
2016 static int
2017 btree_remove(hammer_cursor_t cursor)
2018 {
2019         hammer_node_ondisk_t ondisk;
2020         hammer_btree_elm_t elm;
2021         hammer_node_t node;
2022         hammer_node_t parent;
2023         const int esize = sizeof(*elm);
2024         int error;
2025
2026         node = cursor->node;
2027
2028         /*
2029          * When deleting the root of the filesystem convert it to
2030          * an empty leaf node.  Internal nodes cannot be empty.
2031          */
2032         ondisk = node->ondisk;
2033         if (ondisk->parent == 0) {
2034                 KKASSERT(cursor->parent == NULL);
2035                 hammer_modify_node_all(cursor->trans, node);
2036                 KKASSERT(ondisk == node->ondisk);
2037                 ondisk->type = HAMMER_BTREE_TYPE_LEAF;
2038                 ondisk->count = 0;
2039                 hammer_modify_node_done(node);
2040                 cursor->index = 0;
2041                 return(0);
2042         }
2043
2044         parent = cursor->parent;
2045         hammer_cursor_removed_node(node, parent, cursor->parent_index);
2046
2047         /*
2048          * Attempt to remove the parent's reference to the child.  If the
2049          * parent would become empty we have to recurse.  If we fail we
2050          * leave the parent pointing to an empty leaf node.
2051          */
2052         if (parent->ondisk->count == 1) {
2053                 /*
2054                  * This special cursor_up_locked() call leaves the original
2055                  * node exclusively locked and referenced, leaves the
2056                  * original parent locked (as the new node), and locks the
2057                  * new parent.  It can return EDEADLK.
2058                  */
2059                 error = hammer_cursor_up_locked(cursor);
2060                 if (error == 0) {
2061                         error = btree_remove(cursor);
2062                         if (error == 0) {
2063                                 hammer_modify_node_all(cursor->trans, node);
2064                                 ondisk = node->ondisk;
2065                                 ondisk->type = HAMMER_BTREE_TYPE_DELETED;
2066                                 ondisk->count = 0;
2067                                 hammer_modify_node_done(node);
2068                                 hammer_flush_node(node);
2069                                 hammer_delete_node(cursor->trans, node);
2070                         } else {
2071                                 kprintf("Warning: BTREE_REMOVE: Defering "
2072                                         "parent removal1 @ %016llx, skipping\n",
2073                                         node->node_offset);
2074                         }
2075                         hammer_unlock(&node->lock);
2076                         hammer_rel_node(node);
2077                 } else {
2078                         kprintf("Warning: BTREE_REMOVE: Defering parent "
2079                                 "removal2 @ %016llx, skipping\n",
2080                                 node->node_offset);
2081                 }
2082         } else {
2083                 KKASSERT(parent->ondisk->count > 1);
2084
2085                 /*
2086                  * Delete the subtree reference in the parent
2087                  */
2088                 hammer_modify_node_all(cursor->trans, parent);
2089                 ondisk = parent->ondisk;
2090                 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_INTERNAL);
2091
2092                 elm = &ondisk->elms[cursor->parent_index];
2093                 KKASSERT(elm->internal.subtree_offset == node->node_offset);
2094                 KKASSERT(ondisk->count > 0);
2095                 bcopy(&elm[1], &elm[0],
2096                       (ondisk->count - cursor->parent_index) * esize);
2097                 --ondisk->count;
2098                 hammer_modify_node_done(parent);
2099                 hammer_flush_node(node);
2100                 hammer_delete_node(cursor->trans, node);
2101
2102                 /*
2103                  * cursor->node is invalid, cursor up to make the cursor
2104                  * valid again.
2105                  */
2106                 error = hammer_cursor_up(cursor);
2107         }
2108         return (error);
2109 }
2110
2111 /*
2112  * Propagate cursor->trans->tid up the B-Tree starting at the current
2113  * cursor position using pseudofs info gleaned from the passed inode.
2114  *
2115  * The passed inode has no relationship to the cursor position other
2116  * then being in the same pseudofs as the insertion or deletion we
2117  * are propagating the mirror_tid for.
2118  */
2119 void
2120 hammer_btree_do_propagation(hammer_cursor_t cursor, hammer_inode_t ip,
2121                             hammer_btree_leaf_elm_t leaf)
2122 {
2123         hammer_pseudofs_inmem_t pfsm;
2124         int error;
2125
2126         /*
2127          * We only propagate the mirror_tid up if we are in master or slave
2128          * mode.  We do not bother if we are in no-mirror mode.
2129          */
2130         pfsm = ip->pfsm;
2131         KKASSERT(pfsm != NULL);
2132         if (pfsm->pfsd.master_id < 0 &&
2133             (pfsm->pfsd.mirror_flags & HAMMER_PFSD_SLAVE) == 0) {
2134                 return;
2135         }
2136
2137         error = hammer_btree_mirror_propagate(cursor->trans,
2138                                         cursor->parent, cursor->parent_index,
2139                                         cursor->node->ondisk->mirror_tid);
2140         /* XXX */
2141 }
2142
2143
2144 /*
2145  * Propagate a mirror TID update upwards through the B-Tree to the root.
2146  *
2147  * A locked internal node must be passed in.  The node will remain locked
2148  * on return.
2149  *
2150  * This function syncs mirror_tid at the specified internal node's element,
2151  * adjusts the node's aggregation mirror_tid, and then recurses upwards.
2152  */
2153 static int
2154 hammer_btree_mirror_propagate(hammer_transaction_t trans, hammer_node_t node,
2155                               int index, hammer_tid_t mirror_tid)
2156 {
2157         hammer_btree_internal_elm_t elm;
2158         hammer_node_t parent;
2159         int parent_index;
2160         int error;
2161
2162         KKASSERT (node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL);
2163
2164         /*
2165          * Adjust the node's element
2166          */
2167         elm = &node->ondisk->elms[index].internal;
2168         if (elm->mirror_tid >= mirror_tid)
2169                 return(0);
2170         hammer_modify_node(trans, node, &elm->mirror_tid,
2171                            sizeof(elm->mirror_tid));
2172         elm->mirror_tid = mirror_tid;
2173         hammer_modify_node_done(node);
2174
2175         /*
2176          * Adjust the node's mirror_tid aggregator
2177          */
2178         if (node->ondisk->mirror_tid >= mirror_tid)
2179                 return(0);
2180         hammer_modify_node_field(trans, node, mirror_tid);
2181         node->ondisk->mirror_tid = mirror_tid;
2182         hammer_modify_node_done(node);
2183
2184         error = 0;
2185         if (node->ondisk->parent) {
2186                 parent = hammer_btree_get_parent(node, &parent_index,
2187                                                  &error, 1);
2188                 if (parent) {
2189                         hammer_btree_mirror_propagate(trans, parent,
2190                                                       parent_index, mirror_tid);
2191                         hammer_unlock(&parent->lock);
2192                         hammer_rel_node(parent);
2193                 }
2194         }
2195         return(error);
2196 }
2197
2198 hammer_node_t
2199 hammer_btree_get_parent(hammer_node_t node, int *parent_indexp, int *errorp,
2200                         int try_exclusive)
2201 {
2202         hammer_node_t parent;
2203         hammer_btree_elm_t elm;
2204         int i;
2205
2206         /*
2207          * Get the node
2208          */
2209         parent = hammer_get_node(node->hmp, node->ondisk->parent, 0, errorp);
2210         if (*errorp) {
2211                 KKASSERT(parent == NULL);
2212                 return(NULL);
2213         }
2214         KKASSERT ((parent->flags & HAMMER_NODE_DELETED) == 0);
2215
2216         /*
2217          * Lock the node
2218          */
2219         if (try_exclusive) {
2220                 if (hammer_lock_ex_try(&parent->lock)) {
2221                         hammer_rel_node(parent);
2222                         *errorp = EDEADLK;
2223                         return(NULL);
2224                 }
2225         } else {
2226                 hammer_lock_sh(&parent->lock);
2227         }
2228
2229         /*
2230          * Figure out which element in the parent is pointing to the
2231          * child.
2232          */
2233         if (node->ondisk->count) {
2234                 i = hammer_btree_search_node(&node->ondisk->elms[0].base,
2235                                              parent->ondisk);
2236         } else {
2237                 i = 0;
2238         }
2239         while (i < parent->ondisk->count) {
2240                 elm = &parent->ondisk->elms[i];
2241                 if (elm->internal.subtree_offset == node->node_offset)
2242                         break;
2243                 ++i;
2244         }
2245         if (i == parent->ondisk->count) {
2246                 hammer_unlock(&parent->lock);
2247                 panic("Bad B-Tree link: parent %p node %p\n", parent, node);
2248         }
2249         *parent_indexp = i;
2250         KKASSERT(*errorp == 0);
2251         return(parent);
2252 }
2253
2254 /*
2255  * The element (elm) has been moved to a new internal node (node).
2256  *
2257  * If the element represents a pointer to an internal node that node's
2258  * parent must be adjusted to the element's new location.
2259  *
2260  * XXX deadlock potential here with our exclusive locks
2261  */
2262 int
2263 btree_set_parent(hammer_transaction_t trans, hammer_node_t node,
2264                  hammer_btree_elm_t elm)
2265 {
2266         hammer_node_t child;
2267         int error;
2268
2269         error = 0;
2270
2271         switch(elm->base.btype) {
2272         case HAMMER_BTREE_TYPE_INTERNAL:
2273         case HAMMER_BTREE_TYPE_LEAF:
2274                 child = hammer_get_node(node->hmp, elm->internal.subtree_offset,
2275                                         0, &error);
2276                 if (error == 0) {
2277                         hammer_modify_node_field(trans, child, parent);
2278                         child->ondisk->parent = node->node_offset;
2279                         hammer_modify_node_done(child);
2280                         hammer_rel_node(child);
2281                 }
2282                 break;
2283         default:
2284                 break;
2285         }
2286         return(error);
2287 }
2288
2289 /*
2290  * Exclusively lock all the children of node.  This is used by the split
2291  * code to prevent anyone from accessing the children of a cursor node
2292  * while we fix-up its parent offset.
2293  *
2294  * If we don't lock the children we can really mess up cursors which block
2295  * trying to cursor-up into our node.
2296  *
2297  * On failure EDEADLK (or some other error) is returned.  If a deadlock
2298  * error is returned the cursor is adjusted to block on termination.
2299  */
2300 int
2301 hammer_btree_lock_children(hammer_cursor_t cursor,
2302                            struct hammer_node_locklist **locklistp)
2303 {
2304         hammer_node_t node;
2305         hammer_node_locklist_t item;
2306         hammer_node_ondisk_t ondisk;
2307         hammer_btree_elm_t elm;
2308         hammer_node_t child;
2309         int error;
2310         int i;
2311
2312         node = cursor->node;
2313         ondisk = node->ondisk;
2314         error = 0;
2315
2316         /*
2317          * We really do not want to block on I/O with exclusive locks held,
2318          * pre-get the children before trying to lock the mess.
2319          */
2320         for (i = 0; i < ondisk->count; ++i) {
2321                 ++hammer_stats_btree_elements;
2322                 elm = &ondisk->elms[i];
2323                 if (elm->base.btype != HAMMER_BTREE_TYPE_LEAF &&
2324                     elm->base.btype != HAMMER_BTREE_TYPE_INTERNAL) {
2325                         continue;
2326                 }
2327                 child = hammer_get_node(node->hmp,
2328                                         elm->internal.subtree_offset,
2329                                         0, &error);
2330                 if (child)
2331                         hammer_rel_node(child);
2332         }
2333
2334         /*
2335          * Do it for real
2336          */
2337         for (i = 0; error == 0 && i < ondisk->count; ++i) {
2338                 ++hammer_stats_btree_elements;
2339                 elm = &ondisk->elms[i];
2340
2341                 switch(elm->base.btype) {
2342                 case HAMMER_BTREE_TYPE_INTERNAL:
2343                 case HAMMER_BTREE_TYPE_LEAF:
2344                         KKASSERT(elm->internal.subtree_offset != 0);
2345                         child = hammer_get_node(node->hmp,
2346                                                 elm->internal.subtree_offset,
2347                                                 0, &error);
2348                         break;
2349                 default:
2350                         child = NULL;
2351                         break;
2352                 }
2353                 if (child) {
2354                         if (hammer_lock_ex_try(&child->lock) != 0) {
2355                                 if (cursor->deadlk_node == NULL) {
2356                                         cursor->deadlk_node = child;
2357                                         hammer_ref_node(cursor->deadlk_node);
2358                                 }
2359                                 error = EDEADLK;
2360                                 hammer_rel_node(child);
2361                         } else {
2362                                 item = kmalloc(sizeof(*item),
2363                                                 M_HAMMER, M_WAITOK);
2364                                 item->next = *locklistp;
2365                                 item->node = child;
2366                                 *locklistp = item;
2367                         }
2368                 }
2369         }
2370         if (error)
2371                 hammer_btree_unlock_children(locklistp);
2372         return(error);
2373 }
2374
2375
2376 /*
2377  * Release previously obtained node locks.
2378  */
2379 void
2380 hammer_btree_unlock_children(struct hammer_node_locklist **locklistp)
2381 {
2382         hammer_node_locklist_t item;
2383
2384         while ((item = *locklistp) != NULL) {
2385                 *locklistp = item->next;
2386                 hammer_unlock(&item->node->lock);
2387                 hammer_rel_node(item->node);
2388                 kfree(item, M_HAMMER);
2389         }
2390 }
2391
2392 /************************************************************************
2393  *                         MISCELLANIOUS SUPPORT                        *
2394  ************************************************************************/
2395
2396 /*
2397  * Compare two B-Tree elements, return -N, 0, or +N (e.g. similar to strcmp).
2398  *
2399  * Note that for this particular function a return value of -1, 0, or +1
2400  * can denote a match if create_tid is otherwise discounted.  A create_tid
2401  * of zero is considered to be 'infinity' in comparisons.
2402  *
2403  * See also hammer_rec_rb_compare() and hammer_rec_cmp() in hammer_object.c.
2404  */
2405 int
2406 hammer_btree_cmp(hammer_base_elm_t key1, hammer_base_elm_t key2)
2407 {
2408         if (key1->localization < key2->localization)
2409                 return(-5);
2410         if (key1->localization > key2->localization)
2411                 return(5);
2412
2413         if (key1->obj_id < key2->obj_id)
2414                 return(-4);
2415         if (key1->obj_id > key2->obj_id)
2416                 return(4);
2417
2418         if (key1->rec_type < key2->rec_type)
2419                 return(-3);
2420         if (key1->rec_type > key2->rec_type)
2421                 return(3);
2422
2423         if (key1->key < key2->key)
2424                 return(-2);
2425         if (key1->key > key2->key)
2426                 return(2);
2427
2428         /*
2429          * A create_tid of zero indicates a record which is undeletable
2430          * and must be considered to have a value of positive infinity.
2431          */
2432         if (key1->create_tid == 0) {
2433                 if (key2->create_tid == 0)
2434                         return(0);
2435                 return(1);
2436         }
2437         if (key2->create_tid == 0)
2438                 return(-1);
2439         if (key1->create_tid < key2->create_tid)
2440                 return(-1);
2441         if (key1->create_tid > key2->create_tid)
2442                 return(1);
2443         return(0);
2444 }
2445
2446 /*
2447  * Test a timestamp against an element to determine whether the
2448  * element is visible.  A timestamp of 0 means 'infinity'.
2449  */
2450 int
2451 hammer_btree_chkts(hammer_tid_t asof, hammer_base_elm_t base)
2452 {
2453         if (asof == 0) {
2454                 if (base->delete_tid)
2455                         return(1);
2456                 return(0);
2457         }
2458         if (asof < base->create_tid)
2459                 return(-1);
2460         if (base->delete_tid && asof >= base->delete_tid)
2461                 return(1);
2462         return(0);
2463 }
2464
2465 /*
2466  * Create a separator half way inbetween key1 and key2.  For fields just
2467  * one unit apart, the separator will match key2.  key1 is on the left-hand
2468  * side and key2 is on the right-hand side.
2469  *
2470  * key2 must be >= the separator.  It is ok for the separator to match key2.
2471  *
2472  * NOTE: Even if key1 does not match key2, the separator may wind up matching
2473  * key2.
2474  *
2475  * NOTE: It might be beneficial to just scrap this whole mess and just
2476  * set the separator to key2.
2477  */
2478 #define MAKE_SEPARATOR(key1, key2, dest, field) \
2479         dest->field = key1->field + ((key2->field - key1->field + 1) >> 1);
2480
2481 static void
2482 hammer_make_separator(hammer_base_elm_t key1, hammer_base_elm_t key2,
2483                       hammer_base_elm_t dest)
2484 {
2485         bzero(dest, sizeof(*dest));
2486
2487         dest->rec_type = key2->rec_type;
2488         dest->key = key2->key;
2489         dest->obj_id = key2->obj_id;
2490         dest->create_tid = key2->create_tid;
2491
2492         MAKE_SEPARATOR(key1, key2, dest, localization);
2493         if (key1->localization == key2->localization) {
2494                 MAKE_SEPARATOR(key1, key2, dest, obj_id);
2495                 if (key1->obj_id == key2->obj_id) {
2496                         MAKE_SEPARATOR(key1, key2, dest, rec_type);
2497                         if (key1->rec_type == key2->rec_type) {
2498                                 MAKE_SEPARATOR(key1, key2, dest, key);
2499                                 /*
2500                                  * Don't bother creating a separator for
2501                                  * create_tid, which also conveniently avoids
2502                                  * having to handle the create_tid == 0
2503                                  * (infinity) case.  Just leave create_tid
2504                                  * set to key2.
2505                                  *
2506                                  * Worst case, dest matches key2 exactly,
2507                                  * which is acceptable.
2508                                  */
2509                         }
2510                 }
2511         }
2512 }
2513
2514 #undef MAKE_SEPARATOR
2515
2516 /*
2517  * Return whether a generic internal or leaf node is full
2518  */
2519 static int
2520 btree_node_is_full(hammer_node_ondisk_t node)
2521 {
2522         switch(node->type) {
2523         case HAMMER_BTREE_TYPE_INTERNAL:
2524                 if (node->count == HAMMER_BTREE_INT_ELMS)
2525                         return(1);
2526                 break;
2527         case HAMMER_BTREE_TYPE_LEAF:
2528                 if (node->count == HAMMER_BTREE_LEAF_ELMS)
2529                         return(1);
2530                 break;
2531         default:
2532                 panic("illegal btree subtype");
2533         }
2534         return(0);
2535 }
2536
2537 #if 0
2538 static int
2539 btree_max_elements(u_int8_t type)
2540 {
2541         if (type == HAMMER_BTREE_TYPE_LEAF)
2542                 return(HAMMER_BTREE_LEAF_ELMS);
2543         if (type == HAMMER_BTREE_TYPE_INTERNAL)
2544                 return(HAMMER_BTREE_INT_ELMS);
2545         panic("btree_max_elements: bad type %d\n", type);
2546 }
2547 #endif
2548
2549 void
2550 hammer_print_btree_node(hammer_node_ondisk_t ondisk)
2551 {
2552         hammer_btree_elm_t elm;
2553         int i;
2554
2555         kprintf("node %p count=%d parent=%016llx type=%c\n",
2556                 ondisk, ondisk->count, ondisk->parent, ondisk->type);
2557
2558         /*
2559          * Dump both boundary elements if an internal node
2560          */
2561         if (ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) {
2562                 for (i = 0; i <= ondisk->count; ++i) {
2563                         elm = &ondisk->elms[i];
2564                         hammer_print_btree_elm(elm, ondisk->type, i);
2565                 }
2566         } else {
2567                 for (i = 0; i < ondisk->count; ++i) {
2568                         elm = &ondisk->elms[i];
2569                         hammer_print_btree_elm(elm, ondisk->type, i);
2570                 }
2571         }
2572 }
2573
2574 void
2575 hammer_print_btree_elm(hammer_btree_elm_t elm, u_int8_t type, int i)
2576 {
2577         kprintf("  %2d", i);
2578         kprintf("\tobj_id       = %016llx\n", elm->base.obj_id);
2579         kprintf("\tkey          = %016llx\n", elm->base.key);
2580         kprintf("\tcreate_tid   = %016llx\n", elm->base.create_tid);
2581         kprintf("\tdelete_tid   = %016llx\n", elm->base.delete_tid);
2582         kprintf("\trec_type     = %04x\n", elm->base.rec_type);
2583         kprintf("\tobj_type     = %02x\n", elm->base.obj_type);
2584         kprintf("\tbtype        = %02x (%c)\n",
2585                 elm->base.btype,
2586                 (elm->base.btype ? elm->base.btype : '?'));
2587         kprintf("\tlocalization = %02x\n", elm->base.localization);
2588
2589         switch(type) {
2590         case HAMMER_BTREE_TYPE_INTERNAL:
2591                 kprintf("\tsubtree_off  = %016llx\n",
2592                         elm->internal.subtree_offset);
2593                 break;
2594         case HAMMER_BTREE_TYPE_RECORD:
2595                 kprintf("\tdata_offset  = %016llx\n", elm->leaf.data_offset);
2596                 kprintf("\tdata_len     = %08x\n", elm->leaf.data_len);
2597                 kprintf("\tdata_crc     = %08x\n", elm->leaf.data_crc);
2598                 break;
2599         }
2600 }