2 * Copyright (c) 2007-2008 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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
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.
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
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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
34 * $DragonFly: src/sys/vfs/hammer/hammer_btree.c,v 1.70 2008/07/11 01:22:29 dillon Exp $
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.
48 * A B-Tree internal node looks like this:
50 * B N N N N N N B <-- boundary and internal elements
51 * S S S S S S S <-- subtree pointers
53 * A B-Tree leaf node basically looks like this:
55 * L L L L L L L L <-- leaf elemenets
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.
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
68 * B-Trees also make the stacking of trees fairly straightforward.
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
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
85 static int btree_search(hammer_cursor_t cursor, int flags);
86 static int btree_split_internal(hammer_cursor_t cursor);
87 static int btree_split_leaf(hammer_cursor_t cursor);
88 static int btree_remove(hammer_cursor_t cursor);
89 static int btree_node_is_full(hammer_node_ondisk_t node);
90 static int hammer_btree_mirror_propagate(hammer_cursor_t cursor,
91 hammer_tid_t mirror_tid);
92 static void hammer_make_separator(hammer_base_elm_t key1,
93 hammer_base_elm_t key2, hammer_base_elm_t dest);
94 static void hammer_cursor_mirror_filter(hammer_cursor_t cursor);
97 * Iterate records after a search. The cursor is iterated forwards past
98 * the current record until a record matching the key-range requirements
99 * is found. ENOENT is returned if the iteration goes past the ending
102 * The iteration is inclusive of key_beg and can be inclusive or exclusive
103 * of key_end depending on whether HAMMER_CURSOR_END_INCLUSIVE is set.
105 * When doing an as-of search (cursor->asof != 0), key_beg.create_tid
106 * may be modified by B-Tree functions.
108 * cursor->key_beg may or may not be modified by this function during
109 * the iteration. XXX future - in case of an inverted lock we may have
110 * to reinitiate the lookup and set key_beg to properly pick up where we
113 * NOTE! EDEADLK *CANNOT* be returned by this procedure.
116 hammer_btree_iterate(hammer_cursor_t cursor)
118 hammer_node_ondisk_t node;
119 hammer_btree_elm_t elm;
125 * Skip past the current record
127 node = cursor->node->ondisk;
130 if (cursor->index < node->count &&
131 (cursor->flags & HAMMER_CURSOR_ATEDISK)) {
136 * Loop until an element is found or we are done.
140 * We iterate up the tree and then index over one element
141 * while we are at the last element in the current node.
143 * If we are at the root of the filesystem, cursor_up
146 * XXX this could be optimized by storing the information in
147 * the parent reference.
149 * XXX we can lose the node lock temporarily, this could mess
152 ++hammer_stats_btree_iterations;
153 hammer_flusher_clean_loose_ios(cursor->trans->hmp);
155 if (cursor->index == node->count) {
156 if (hammer_debug_btree) {
157 kprintf("BRACKETU %016llx[%d] -> %016llx[%d] (td=%p)\n",
158 cursor->node->node_offset,
160 (cursor->parent ? cursor->parent->node_offset : -1),
161 cursor->parent_index,
164 KKASSERT(cursor->parent == NULL || cursor->parent->ondisk->elms[cursor->parent_index].internal.subtree_offset == cursor->node->node_offset);
165 error = hammer_cursor_up(cursor);
168 /* reload stale pointer */
169 node = cursor->node->ondisk;
170 KKASSERT(cursor->index != node->count);
173 * If we are reblocking we want to return internal
176 if (cursor->flags & HAMMER_CURSOR_REBLOCKING) {
177 cursor->flags |= HAMMER_CURSOR_ATEDISK;
185 * Check internal or leaf element. Determine if the record
186 * at the cursor has gone beyond the end of our range.
188 * We recurse down through internal nodes.
190 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) {
191 elm = &node->elms[cursor->index];
193 r = hammer_btree_cmp(&cursor->key_end, &elm[0].base);
194 s = hammer_btree_cmp(&cursor->key_beg, &elm[1].base);
195 if (hammer_debug_btree) {
196 kprintf("BRACKETL %016llx[%d] %016llx %02x %016llx lo=%02x %d (td=%p)\n",
197 cursor->node->node_offset,
199 elm[0].internal.base.obj_id,
200 elm[0].internal.base.rec_type,
201 elm[0].internal.base.key,
202 elm[0].internal.base.localization,
206 kprintf("BRACKETR %016llx[%d] %016llx %02x %016llx lo=%02x %d\n",
207 cursor->node->node_offset,
209 elm[1].internal.base.obj_id,
210 elm[1].internal.base.rec_type,
211 elm[1].internal.base.key,
212 elm[1].internal.base.localization,
221 if (r == 0 && (cursor->flags &
222 HAMMER_CURSOR_END_INCLUSIVE) == 0) {
231 KKASSERT(elm->internal.subtree_offset != 0);
234 * If running the mirror filter see if we can skip
235 * one or more entire sub-trees. If we can we
236 * return the internal mode and the caller processes
237 * the skipped range (see mirror_read)
239 if (cursor->flags & HAMMER_CURSOR_MIRROR_FILTERED) {
240 if (elm->internal.mirror_tid <
241 cursor->cmirror->mirror_tid) {
242 hammer_cursor_mirror_filter(cursor);
247 error = hammer_cursor_down(cursor);
250 KKASSERT(cursor->index == 0);
251 /* reload stale pointer */
252 node = cursor->node->ondisk;
255 elm = &node->elms[cursor->index];
256 r = hammer_btree_cmp(&cursor->key_end, &elm->base);
257 if (hammer_debug_btree) {
258 kprintf("ELEMENT %016llx:%d %c %016llx %02x %016llx lo=%02x %d\n",
259 cursor->node->node_offset,
261 (elm[0].leaf.base.btype ?
262 elm[0].leaf.base.btype : '?'),
263 elm[0].leaf.base.obj_id,
264 elm[0].leaf.base.rec_type,
265 elm[0].leaf.base.key,
266 elm[0].leaf.base.localization,
276 * We support both end-inclusive and
277 * end-exclusive searches.
280 (cursor->flags & HAMMER_CURSOR_END_INCLUSIVE) == 0) {
285 switch(elm->leaf.base.btype) {
286 case HAMMER_BTREE_TYPE_RECORD:
287 if ((cursor->flags & HAMMER_CURSOR_ASOF) &&
288 hammer_btree_chkts(cursor->asof, &elm->base)) {
301 * node pointer invalid after loop
307 if (hammer_debug_btree) {
308 int i = cursor->index;
309 hammer_btree_elm_t elm = &cursor->node->ondisk->elms[i];
310 kprintf("ITERATE %p:%d %016llx %02x %016llx lo=%02x\n",
312 elm->internal.base.obj_id,
313 elm->internal.base.rec_type,
314 elm->internal.base.key,
315 elm->internal.base.localization
324 * We hit an internal element that we could skip as part of a mirroring
325 * scan. Calculate the entire range being skipped.
327 * It is important to include any gaps between the parent's left_bound
328 * and the node's left_bound, and same goes for the right side.
331 hammer_cursor_mirror_filter(hammer_cursor_t cursor)
333 struct hammer_cmirror *cmirror;
334 hammer_node_ondisk_t ondisk;
335 hammer_btree_elm_t elm;
337 ondisk = cursor->node->ondisk;
338 cmirror = cursor->cmirror;
341 * Calculate the skipped range
343 elm = &ondisk->elms[cursor->index];
344 if (cursor->index == 0)
345 cmirror->skip_beg = *cursor->left_bound;
347 cmirror->skip_beg = elm->internal.base;
348 while (cursor->index < ondisk->count) {
349 if (elm->internal.mirror_tid >= cmirror->mirror_tid)
354 if (cursor->index == ondisk->count)
355 cmirror->skip_end = *cursor->right_bound;
357 cmirror->skip_end = elm->internal.base;
360 * clip the returned result.
362 if (hammer_btree_cmp(&cmirror->skip_beg, &cursor->key_beg) < 0)
363 cmirror->skip_beg = cursor->key_beg;
364 if (hammer_btree_cmp(&cmirror->skip_end, &cursor->key_end) > 0)
365 cmirror->skip_end = cursor->key_end;
369 * Iterate in the reverse direction. This is used by the pruning code to
370 * avoid overlapping records.
373 hammer_btree_iterate_reverse(hammer_cursor_t cursor)
375 hammer_node_ondisk_t node;
376 hammer_btree_elm_t elm;
381 /* mirror filtering not supported for reverse iteration */
382 KKASSERT ((cursor->flags & HAMMER_CURSOR_MIRROR_FILTERED) == 0);
385 * Skip past the current record. For various reasons the cursor
386 * may end up set to -1 or set to point at the end of the current
387 * node. These cases must be addressed.
389 node = cursor->node->ondisk;
392 if (cursor->index != -1 &&
393 (cursor->flags & HAMMER_CURSOR_ATEDISK)) {
396 if (cursor->index == cursor->node->ondisk->count)
400 * Loop until an element is found or we are done.
403 ++hammer_stats_btree_iterations;
404 hammer_flusher_clean_loose_ios(cursor->trans->hmp);
407 * We iterate up the tree and then index over one element
408 * while we are at the last element in the current node.
410 if (cursor->index == -1) {
411 error = hammer_cursor_up(cursor);
413 cursor->index = 0; /* sanity */
416 /* reload stale pointer */
417 node = cursor->node->ondisk;
418 KKASSERT(cursor->index != node->count);
424 * Check internal or leaf element. Determine if the record
425 * at the cursor has gone beyond the end of our range.
427 * We recurse down through internal nodes.
429 KKASSERT(cursor->index != node->count);
430 if (node->type == HAMMER_BTREE_TYPE_INTERNAL) {
431 elm = &node->elms[cursor->index];
432 r = hammer_btree_cmp(&cursor->key_end, &elm[0].base);
433 s = hammer_btree_cmp(&cursor->key_beg, &elm[1].base);
434 if (hammer_debug_btree) {
435 kprintf("BRACKETL %016llx[%d] %016llx %02x %016llx lo=%02x %d\n",
436 cursor->node->node_offset,
438 elm[0].internal.base.obj_id,
439 elm[0].internal.base.rec_type,
440 elm[0].internal.base.key,
441 elm[0].internal.base.localization,
444 kprintf("BRACKETR %016llx[%d] %016llx %02x %016llx lo=%02x %d\n",
445 cursor->node->node_offset,
447 elm[1].internal.base.obj_id,
448 elm[1].internal.base.rec_type,
449 elm[1].internal.base.key,
450 elm[1].internal.base.localization,
464 KKASSERT(elm->internal.subtree_offset != 0);
466 error = hammer_cursor_down(cursor);
469 KKASSERT(cursor->index == 0);
470 /* reload stale pointer */
471 node = cursor->node->ondisk;
473 /* this can assign -1 if the leaf was empty */
474 cursor->index = node->count - 1;
477 elm = &node->elms[cursor->index];
478 s = hammer_btree_cmp(&cursor->key_beg, &elm->base);
479 if (hammer_debug_btree) {
480 kprintf("ELEMENT %016llx:%d %c %016llx %02x %016llx lo=%02x %d\n",
481 cursor->node->node_offset,
483 (elm[0].leaf.base.btype ?
484 elm[0].leaf.base.btype : '?'),
485 elm[0].leaf.base.obj_id,
486 elm[0].leaf.base.rec_type,
487 elm[0].leaf.base.key,
488 elm[0].leaf.base.localization,
497 switch(elm->leaf.base.btype) {
498 case HAMMER_BTREE_TYPE_RECORD:
499 if ((cursor->flags & HAMMER_CURSOR_ASOF) &&
500 hammer_btree_chkts(cursor->asof, &elm->base)) {
513 * node pointer invalid after loop
519 if (hammer_debug_btree) {
520 int i = cursor->index;
521 hammer_btree_elm_t elm = &cursor->node->ondisk->elms[i];
522 kprintf("ITERATE %p:%d %016llx %02x %016llx lo=%02x\n",
524 elm->internal.base.obj_id,
525 elm->internal.base.rec_type,
526 elm->internal.base.key,
527 elm->internal.base.localization
536 * Lookup cursor->key_beg. 0 is returned on success, ENOENT if the entry
537 * could not be found, EDEADLK if inserting and a retry is needed, and a
538 * fatal error otherwise. When retrying, the caller must terminate the
539 * cursor and reinitialize it. EDEADLK cannot be returned if not inserting.
541 * The cursor is suitably positioned for a deletion on success, and suitably
542 * positioned for an insertion on ENOENT if HAMMER_CURSOR_INSERT was
545 * The cursor may begin anywhere, the search will traverse the tree in
546 * either direction to locate the requested element.
548 * Most of the logic implementing historical searches is handled here. We
549 * do an initial lookup with create_tid set to the asof TID. Due to the
550 * way records are laid out, a backwards iteration may be required if
551 * ENOENT is returned to locate the historical record. Here's the
554 * create_tid: 10 15 20
558 * Lets say we want to do a lookup AS-OF timestamp 17. We will traverse
559 * LEAF2 but the only record in LEAF2 has a create_tid of 18, which is
560 * not visible and thus causes ENOENT to be returned. We really need
561 * to check record 11 in LEAF1. If it also fails then the search fails
562 * (e.g. it might represent the range 11-16 and thus still not match our
563 * AS-OF timestamp of 17). Note that LEAF1 could be empty, requiring
564 * further iterations.
566 * If this case occurs btree_search() will set HAMMER_CURSOR_CREATE_CHECK
567 * and the cursor->create_check TID if an iteration might be needed.
568 * In the above example create_check would be set to 14.
571 hammer_btree_lookup(hammer_cursor_t cursor)
575 KKASSERT ((cursor->flags & HAMMER_CURSOR_INSERT) == 0 ||
576 cursor->trans->sync_lock_refs > 0);
577 ++hammer_stats_btree_lookups;
578 if (cursor->flags & HAMMER_CURSOR_ASOF) {
579 KKASSERT((cursor->flags & HAMMER_CURSOR_INSERT) == 0);
580 cursor->key_beg.create_tid = cursor->asof;
582 cursor->flags &= ~HAMMER_CURSOR_CREATE_CHECK;
583 error = btree_search(cursor, 0);
584 if (error != ENOENT ||
585 (cursor->flags & HAMMER_CURSOR_CREATE_CHECK) == 0) {
588 * Stop if error other then ENOENT.
589 * Stop if ENOENT and not special case.
593 if (hammer_debug_btree) {
594 kprintf("CREATE_CHECK %016llx\n",
595 cursor->create_check);
597 cursor->key_beg.create_tid = cursor->create_check;
601 error = btree_search(cursor, 0);
604 error = hammer_btree_extract(cursor, cursor->flags);
609 * Execute the logic required to start an iteration. The first record
610 * located within the specified range is returned and iteration control
611 * flags are adjusted for successive hammer_btree_iterate() calls.
614 hammer_btree_first(hammer_cursor_t cursor)
618 error = hammer_btree_lookup(cursor);
619 if (error == ENOENT) {
620 cursor->flags &= ~HAMMER_CURSOR_ATEDISK;
621 error = hammer_btree_iterate(cursor);
623 cursor->flags |= HAMMER_CURSOR_ATEDISK;
628 * Similarly but for an iteration in the reverse direction.
630 * Set ATEDISK when iterating backwards to skip the current entry,
631 * which after an ENOENT lookup will be pointing beyond our end point.
634 hammer_btree_last(hammer_cursor_t cursor)
636 struct hammer_base_elm save;
639 save = cursor->key_beg;
640 cursor->key_beg = cursor->key_end;
641 error = hammer_btree_lookup(cursor);
642 cursor->key_beg = save;
643 if (error == ENOENT ||
644 (cursor->flags & HAMMER_CURSOR_END_INCLUSIVE) == 0) {
645 cursor->flags |= HAMMER_CURSOR_ATEDISK;
646 error = hammer_btree_iterate_reverse(cursor);
648 cursor->flags |= HAMMER_CURSOR_ATEDISK;
653 * Extract the record and/or data associated with the cursor's current
654 * position. Any prior record or data stored in the cursor is replaced.
655 * The cursor must be positioned at a leaf node.
657 * NOTE: All extractions occur at the leaf of the B-Tree.
660 hammer_btree_extract(hammer_cursor_t cursor, int flags)
663 hammer_node_ondisk_t node;
664 hammer_btree_elm_t elm;
665 hammer_off_t data_off;
670 * The case where the data reference resolves to the same buffer
671 * as the record reference must be handled.
673 node = cursor->node->ondisk;
674 elm = &node->elms[cursor->index];
676 hmp = cursor->node->hmp;
679 * There is nothing to extract for an internal element.
681 if (node->type == HAMMER_BTREE_TYPE_INTERNAL)
685 * Only record types have data.
687 KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF);
688 cursor->leaf = &elm->leaf;
690 if ((flags & HAMMER_CURSOR_GET_DATA) == 0)
692 if (elm->leaf.base.btype != HAMMER_BTREE_TYPE_RECORD)
694 data_off = elm->leaf.data_offset;
695 data_len = elm->leaf.data_len;
702 KKASSERT(data_len >= 0 && data_len <= HAMMER_XBUFSIZE);
703 cursor->data = hammer_bread_ext(hmp, data_off, data_len,
704 &error, &cursor->data_buffer);
705 if (hammer_crc_test_leaf(cursor->data, &elm->leaf) == 0)
706 Debugger("CRC FAILED: DATA");
712 * Insert a leaf element into the B-Tree at the current cursor position.
713 * The cursor is positioned such that the element at and beyond the cursor
714 * are shifted to make room for the new record.
716 * The caller must call hammer_btree_lookup() with the HAMMER_CURSOR_INSERT
717 * flag set and that call must return ENOENT before this function can be
720 * The caller may depend on the cursor's exclusive lock after return to
721 * interlock frontend visibility (see HAMMER_RECF_CONVERT_DELETE).
723 * ENOSPC is returned if there is no room to insert a new record.
726 hammer_btree_insert(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm,
729 hammer_node_ondisk_t node;
734 if ((error = hammer_cursor_upgrade_node(cursor)) != 0)
736 ++hammer_stats_btree_inserts;
739 * Insert the element at the leaf node and update the count in the
740 * parent. It is possible for parent to be NULL, indicating that
741 * the filesystem's ROOT B-Tree node is a leaf itself, which is
742 * possible. The root inode can never be deleted so the leaf should
745 * Remember that the right-hand boundary is not included in the
748 hammer_modify_node_all(cursor->trans, cursor->node);
749 node = cursor->node->ondisk;
751 KKASSERT(elm->base.btype != 0);
752 KKASSERT(node->type == HAMMER_BTREE_TYPE_LEAF);
753 KKASSERT(node->count < HAMMER_BTREE_LEAF_ELMS);
754 if (i != node->count) {
755 bcopy(&node->elms[i], &node->elms[i+1],
756 (node->count - i) * sizeof(*elm));
758 node->elms[i].leaf = *elm;
760 hammer_cursor_inserted_element(cursor->node, i);
763 * Update the leaf node's aggregate mirror_tid for mirroring
766 if (node->mirror_tid < elm->base.delete_tid) {
767 node->mirror_tid = elm->base.delete_tid;
770 if (node->mirror_tid < elm->base.create_tid) {
771 node->mirror_tid = elm->base.create_tid;
774 hammer_modify_node_done(cursor->node);
777 * Debugging sanity checks.
779 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->base) <= 0);
780 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->base) > 0);
782 KKASSERT(hammer_btree_cmp(&node->elms[i-1].leaf.base, &elm->base) < 0);
784 if (i != node->count - 1)
785 KKASSERT(hammer_btree_cmp(&node->elms[i+1].leaf.base, &elm->base) > 0);
791 * Delete a record from the B-Tree at the current cursor position.
792 * The cursor is positioned such that the current element is the one
795 * On return the cursor will be positioned after the deleted element and
796 * MAY point to an internal node. It will be suitable for the continuation
797 * of an iteration but not for an insertion or deletion.
799 * Deletions will attempt to partially rebalance the B-Tree in an upward
800 * direction, but will terminate rather then deadlock. Empty internal nodes
801 * are never allowed by a deletion which deadlocks may end up giving us an
802 * empty leaf. The pruner will clean up and rebalance the tree.
804 * This function can return EDEADLK, requiring the caller to retry the
805 * operation after clearing the deadlock.
808 hammer_btree_delete(hammer_cursor_t cursor)
810 hammer_node_ondisk_t ondisk;
812 hammer_node_t parent;
816 KKASSERT (cursor->trans->sync_lock_refs > 0);
817 if ((error = hammer_cursor_upgrade(cursor)) != 0)
819 ++hammer_stats_btree_deletes;
822 * Delete the element from the leaf node.
824 * Remember that leaf nodes do not have boundaries.
827 ondisk = node->ondisk;
830 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_LEAF);
831 KKASSERT(i >= 0 && i < ondisk->count);
832 hammer_modify_node_all(cursor->trans, node);
833 if (i + 1 != ondisk->count) {
834 bcopy(&ondisk->elms[i+1], &ondisk->elms[i],
835 (ondisk->count - i - 1) * sizeof(ondisk->elms[0]));
838 hammer_modify_node_done(node);
839 hammer_cursor_deleted_element(node, i);
842 * Validate local parent
844 if (ondisk->parent) {
845 parent = cursor->parent;
847 KKASSERT(parent != NULL);
848 KKASSERT(parent->node_offset == ondisk->parent);
852 * If the leaf becomes empty it must be detached from the parent,
853 * potentially recursing through to the filesystem root.
855 * This may reposition the cursor at one of the parent's of the
858 * Ignore deadlock errors, that simply means that btree_remove
859 * was unable to recurse and had to leave us with an empty leaf.
861 KKASSERT(cursor->index <= ondisk->count);
862 if (ondisk->count == 0) {
863 error = btree_remove(cursor);
864 if (error == EDEADLK)
869 KKASSERT(cursor->parent == NULL ||
870 cursor->parent_index < cursor->parent->ondisk->count);
875 * PRIMAY B-TREE SEARCH SUPPORT PROCEDURE
877 * Search the filesystem B-Tree for cursor->key_beg, return the matching node.
879 * The search can begin ANYWHERE in the B-Tree. As a first step the search
880 * iterates up the tree as necessary to properly position itself prior to
881 * actually doing the sarch.
883 * INSERTIONS: The search will split full nodes and leaves on its way down
884 * and guarentee that the leaf it ends up on is not full. If we run out
885 * of space the search continues to the leaf (to position the cursor for
886 * the spike), but ENOSPC is returned.
888 * The search is only guarenteed to end up on a leaf if an error code of 0
889 * is returned, or if inserting and an error code of ENOENT is returned.
890 * Otherwise it can stop at an internal node. On success a search returns
893 * COMPLEXITY WARNING! This is the core B-Tree search code for the entire
894 * filesystem, and it is not simple code. Please note the following facts:
896 * - Internal node recursions have a boundary on the left AND right. The
897 * right boundary is non-inclusive. The create_tid is a generic part
898 * of the key for internal nodes.
900 * - Leaf nodes contain terminal elements only now.
902 * - Filesystem lookups typically set HAMMER_CURSOR_ASOF, indicating a
903 * historical search. ASOF and INSERT are mutually exclusive. When
904 * doing an as-of lookup btree_search() checks for a right-edge boundary
905 * case. If while recursing down the left-edge differs from the key
906 * by ONLY its create_tid, HAMMER_CURSOR_CREATE_CHECK is set along
907 * with cursor->create_check. This is used by btree_lookup() to iterate.
908 * The iteration backwards because as-of searches can wind up going
909 * down the wrong branch of the B-Tree.
913 btree_search(hammer_cursor_t cursor, int flags)
915 hammer_node_ondisk_t node;
916 hammer_btree_elm_t elm;
923 flags |= cursor->flags;
924 ++hammer_stats_btree_searches;
926 if (hammer_debug_btree) {
927 kprintf("SEARCH %016llx[%d] %016llx %02x key=%016llx cre=%016llx lo=%02x (td = %p)\n",
928 cursor->node->node_offset,
930 cursor->key_beg.obj_id,
931 cursor->key_beg.rec_type,
933 cursor->key_beg.create_tid,
934 cursor->key_beg.localization,
938 kprintf("SEARCHP %016llx[%d] (%016llx/%016llx %016llx/%016llx) (%p/%p %p/%p)\n",
939 cursor->parent->node_offset, cursor->parent_index,
940 cursor->left_bound->obj_id,
941 cursor->parent->ondisk->elms[cursor->parent_index].internal.base.obj_id,
942 cursor->right_bound->obj_id,
943 cursor->parent->ondisk->elms[cursor->parent_index+1].internal.base.obj_id,
945 &cursor->parent->ondisk->elms[cursor->parent_index],
947 &cursor->parent->ondisk->elms[cursor->parent_index+1]
952 * Move our cursor up the tree until we find a node whos range covers
953 * the key we are trying to locate.
955 * The left bound is inclusive, the right bound is non-inclusive.
956 * It is ok to cursor up too far.
959 r = hammer_btree_cmp(&cursor->key_beg, cursor->left_bound);
960 s = hammer_btree_cmp(&cursor->key_beg, cursor->right_bound);
963 KKASSERT(cursor->parent);
964 ++hammer_stats_btree_iterations;
965 error = hammer_cursor_up(cursor);
971 * The delete-checks below are based on node, not parent. Set the
972 * initial delete-check based on the parent.
975 KKASSERT(cursor->left_bound->create_tid != 1);
976 cursor->create_check = cursor->left_bound->create_tid - 1;
977 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK;
981 * We better have ended up with a node somewhere.
983 KKASSERT(cursor->node != NULL);
986 * If we are inserting we can't start at a full node if the parent
987 * is also full (because there is no way to split the node),
988 * continue running up the tree until the requirement is satisfied
989 * or we hit the root of the filesystem.
991 * (If inserting we aren't doing an as-of search so we don't have
992 * to worry about create_check).
994 while ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) {
995 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) {
996 if (btree_node_is_full(cursor->node->ondisk) == 0)
999 if (btree_node_is_full(cursor->node->ondisk) ==0)
1002 if (cursor->node->ondisk->parent == 0 ||
1003 cursor->parent->ondisk->count != HAMMER_BTREE_INT_ELMS) {
1006 ++hammer_stats_btree_iterations;
1007 error = hammer_cursor_up(cursor);
1008 /* node may have become stale */
1014 * Push down through internal nodes to locate the requested key.
1016 node = cursor->node->ondisk;
1017 while (node->type == HAMMER_BTREE_TYPE_INTERNAL) {
1019 * Scan the node to find the subtree index to push down into.
1020 * We go one-past, then back-up.
1022 * We must proactively remove deleted elements which may
1023 * have been left over from a deadlocked btree_remove().
1025 * The left and right boundaries are included in the loop
1026 * in order to detect edge cases.
1028 * If the separator only differs by create_tid (r == 1)
1029 * and we are doing an as-of search, we may end up going
1030 * down a branch to the left of the one containing the
1031 * desired key. This requires numerous special cases.
1033 ++hammer_stats_btree_iterations;
1034 if (hammer_debug_btree) {
1035 kprintf("SEARCH-I %016llx count=%d\n",
1036 cursor->node->node_offset,
1041 * Try to shortcut the search before dropping into the
1042 * linear loop. Locate the first node where r <= 1.
1044 i = hammer_btree_search_node(&cursor->key_beg, node);
1045 while (i <= node->count) {
1046 ++hammer_stats_btree_elements;
1047 elm = &node->elms[i];
1048 r = hammer_btree_cmp(&cursor->key_beg, &elm->base);
1049 if (hammer_debug_btree > 2) {
1050 kprintf(" IELM %p %d r=%d\n",
1051 &node->elms[i], i, r);
1056 KKASSERT(elm->base.create_tid != 1);
1057 cursor->create_check = elm->base.create_tid - 1;
1058 cursor->flags |= HAMMER_CURSOR_CREATE_CHECK;
1062 if (hammer_debug_btree) {
1063 kprintf("SEARCH-I preI=%d/%d r=%d\n",
1068 * These cases occur when the parent's idea of the boundary
1069 * is wider then the child's idea of the boundary, and
1070 * require special handling. If not inserting we can
1071 * terminate the search early for these cases but the
1072 * child's boundaries cannot be unconditionally modified.
1076 * If i == 0 the search terminated to the LEFT of the
1077 * left_boundary but to the RIGHT of the parent's left
1082 elm = &node->elms[0];
1085 * If we aren't inserting we can stop here.
1087 if ((flags & (HAMMER_CURSOR_INSERT |
1088 HAMMER_CURSOR_PRUNING)) == 0) {
1094 * Correct a left-hand boundary mismatch.
1096 * We can only do this if we can upgrade the lock,
1097 * and synchronized as a background cursor (i.e.
1098 * inserting or pruning).
1100 * WARNING: We can only do this if inserting, i.e.
1101 * we are running on the backend.
1103 if ((error = hammer_cursor_upgrade(cursor)) != 0)
1105 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND);
1106 hammer_modify_node_field(cursor->trans, cursor->node,
1108 save = node->elms[0].base.btype;
1109 node->elms[0].base = *cursor->left_bound;
1110 node->elms[0].base.btype = save;
1111 hammer_modify_node_done(cursor->node);
1112 } else if (i == node->count + 1) {
1114 * If i == node->count + 1 the search terminated to
1115 * the RIGHT of the right boundary but to the LEFT
1116 * of the parent's right boundary. If we aren't
1117 * inserting we can stop here.
1119 * Note that the last element in this case is
1120 * elms[i-2] prior to adjustments to 'i'.
1123 if ((flags & (HAMMER_CURSOR_INSERT |
1124 HAMMER_CURSOR_PRUNING)) == 0) {
1130 * Correct a right-hand boundary mismatch.
1131 * (actual push-down record is i-2 prior to
1132 * adjustments to i).
1134 * We can only do this if we can upgrade the lock,
1135 * and synchronized as a background cursor (i.e.
1136 * inserting or pruning).
1138 * WARNING: We can only do this if inserting, i.e.
1139 * we are running on the backend.
1141 if ((error = hammer_cursor_upgrade(cursor)) != 0)
1143 elm = &node->elms[i];
1144 KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND);
1145 hammer_modify_node(cursor->trans, cursor->node,
1146 &elm->base, sizeof(elm->base));
1147 elm->base = *cursor->right_bound;
1148 hammer_modify_node_done(cursor->node);
1152 * The push-down index is now i - 1. If we had
1153 * terminated on the right boundary this will point
1154 * us at the last element.
1159 elm = &node->elms[i];
1161 if (hammer_debug_btree) {
1162 kprintf("RESULT-I %016llx[%d] %016llx %02x "
1163 "key=%016llx cre=%016llx lo=%02x\n",
1164 cursor->node->node_offset,
1166 elm->internal.base.obj_id,
1167 elm->internal.base.rec_type,
1168 elm->internal.base.key,
1169 elm->internal.base.create_tid,
1170 elm->internal.base.localization
1175 * We better have a valid subtree offset.
1177 KKASSERT(elm->internal.subtree_offset != 0);
1180 * Handle insertion and deletion requirements.
1182 * If inserting split full nodes. The split code will
1183 * adjust cursor->node and cursor->index if the current
1184 * index winds up in the new node.
1186 * If inserting and a left or right edge case was detected,
1187 * we cannot correct the left or right boundary and must
1188 * prepend and append an empty leaf node in order to make
1189 * the boundary correction.
1191 * If we run out of space we set enospc and continue on
1192 * to a leaf to provide the spike code with a good point
1195 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0) {
1196 if (btree_node_is_full(node)) {
1197 error = btree_split_internal(cursor);
1199 if (error != ENOSPC)
1204 * reload stale pointers
1207 node = cursor->node->ondisk;
1212 * Push down (push into new node, existing node becomes
1213 * the parent) and continue the search.
1215 error = hammer_cursor_down(cursor);
1216 /* node may have become stale */
1219 node = cursor->node->ondisk;
1223 * We are at a leaf, do a linear search of the key array.
1225 * On success the index is set to the matching element and 0
1228 * On failure the index is set to the insertion point and ENOENT
1231 * Boundaries are not stored in leaf nodes, so the index can wind
1232 * up to the left of element 0 (index == 0) or past the end of
1233 * the array (index == node->count). It is also possible that the
1234 * leaf might be empty.
1236 ++hammer_stats_btree_iterations;
1237 KKASSERT (node->type == HAMMER_BTREE_TYPE_LEAF);
1238 KKASSERT(node->count <= HAMMER_BTREE_LEAF_ELMS);
1239 if (hammer_debug_btree) {
1240 kprintf("SEARCH-L %016llx count=%d\n",
1241 cursor->node->node_offset,
1246 * Try to shortcut the search before dropping into the
1247 * linear loop. Locate the first node where r <= 1.
1249 i = hammer_btree_search_node(&cursor->key_beg, node);
1250 while (i < node->count) {
1251 ++hammer_stats_btree_elements;
1252 elm = &node->elms[i];
1254 r = hammer_btree_cmp(&cursor->key_beg, &elm->leaf.base);
1256 if (hammer_debug_btree > 1)
1257 kprintf(" ELM %p %d r=%d\n", &node->elms[i], i, r);
1260 * We are at a record element. Stop if we've flipped past
1261 * key_beg, not counting the create_tid test. Allow the
1262 * r == 1 case (key_beg > element but differs only by its
1263 * create_tid) to fall through to the AS-OF check.
1265 KKASSERT (elm->leaf.base.btype == HAMMER_BTREE_TYPE_RECORD);
1275 * Check our as-of timestamp against the element.
1277 if (flags & HAMMER_CURSOR_ASOF) {
1278 if (hammer_btree_chkts(cursor->asof,
1279 &node->elms[i].base) != 0) {
1285 if (r > 0) { /* can only be +1 */
1293 if (hammer_debug_btree) {
1294 kprintf("RESULT-L %016llx[%d] (SUCCESS)\n",
1295 cursor->node->node_offset, i);
1301 * The search of the leaf node failed. i is the insertion point.
1304 if (hammer_debug_btree) {
1305 kprintf("RESULT-L %016llx[%d] (FAILED)\n",
1306 cursor->node->node_offset, i);
1310 * No exact match was found, i is now at the insertion point.
1312 * If inserting split a full leaf before returning. This
1313 * may have the side effect of adjusting cursor->node and
1317 if ((flags & HAMMER_CURSOR_INSERT) && enospc == 0 &&
1318 btree_node_is_full(node)) {
1319 error = btree_split_leaf(cursor);
1321 if (error != ENOSPC)
1326 * reload stale pointers
1330 node = &cursor->node->internal;
1335 * We reached a leaf but did not find the key we were looking for.
1336 * If this is an insert we will be properly positioned for an insert
1337 * (ENOENT) or spike (ENOSPC) operation.
1339 error = enospc ? ENOSPC : ENOENT;
1345 * Heuristical search for the first element whos comparison is <= 1. May
1346 * return an index whos compare result is > 1 but may only return an index
1347 * whos compare result is <= 1 if it is the first element with that result.
1350 hammer_btree_search_node(hammer_base_elm_t elm, hammer_node_ondisk_t node)
1358 * Don't bother if the node does not have very many elements
1363 i = b + (s - b) / 2;
1364 ++hammer_stats_btree_elements;
1365 r = hammer_btree_cmp(elm, &node->elms[i].leaf.base);
1376 /************************************************************************
1377 * SPLITTING AND MERGING *
1378 ************************************************************************
1380 * These routines do all the dirty work required to split and merge nodes.
1384 * Split an internal node into two nodes and move the separator at the split
1385 * point to the parent.
1387 * (cursor->node, cursor->index) indicates the element the caller intends
1388 * to push into. We will adjust node and index if that element winds
1389 * up in the split node.
1391 * If we are at the root of the filesystem a new root must be created with
1392 * two elements, one pointing to the original root and one pointing to the
1393 * newly allocated split node.
1397 btree_split_internal(hammer_cursor_t cursor)
1399 hammer_node_ondisk_t ondisk;
1401 hammer_node_t parent;
1402 hammer_node_t new_node;
1403 hammer_btree_elm_t elm;
1404 hammer_btree_elm_t parent_elm;
1405 hammer_node_locklist_t locklist = NULL;
1406 hammer_mount_t hmp = cursor->trans->hmp;
1412 const int esize = sizeof(*elm);
1414 error = hammer_btree_lock_children(cursor, &locklist);
1417 if ((error = hammer_cursor_upgrade(cursor)) != 0)
1419 ++hammer_stats_btree_splits;
1422 * We are splitting but elms[split] will be promoted to the parent,
1423 * leaving the right hand node with one less element. If the
1424 * insertion point will be on the left-hand side adjust the split
1425 * point to give the right hand side one additional node.
1427 node = cursor->node;
1428 ondisk = node->ondisk;
1429 split = (ondisk->count + 1) / 2;
1430 if (cursor->index <= split)
1434 * If we are at the root of the filesystem, create a new root node
1435 * with 1 element and split normally. Avoid making major
1436 * modifications until we know the whole operation will work.
1438 if (ondisk->parent == 0) {
1439 parent = hammer_alloc_btree(cursor->trans, &error);
1442 hammer_lock_ex(&parent->lock);
1443 hammer_modify_node_noundo(cursor->trans, parent);
1444 ondisk = parent->ondisk;
1447 ondisk->mirror_tid = node->ondisk->mirror_tid;
1448 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL;
1449 ondisk->elms[0].base = hmp->root_btree_beg;
1450 ondisk->elms[0].base.btype = node->ondisk->type;
1451 ondisk->elms[0].internal.subtree_offset = node->node_offset;
1452 ondisk->elms[1].base = hmp->root_btree_end;
1453 hammer_modify_node_done(parent);
1454 /* ondisk->elms[1].base.btype - not used */
1456 parent_index = 0; /* index of current node in parent */
1459 parent = cursor->parent;
1460 parent_index = cursor->parent_index;
1464 * Split node into new_node at the split point.
1466 * B O O O P N N B <-- P = node->elms[split]
1467 * 0 1 2 3 4 5 6 <-- subtree indices
1472 * B O O O B B N N B <--- inner boundary points are 'P'
1476 new_node = hammer_alloc_btree(cursor->trans, &error);
1477 if (new_node == NULL) {
1479 hammer_unlock(&parent->lock);
1480 hammer_delete_node(cursor->trans, parent);
1481 hammer_rel_node(parent);
1485 hammer_lock_ex(&new_node->lock);
1488 * Create the new node. P becomes the left-hand boundary in the
1489 * new node. Copy the right-hand boundary as well.
1491 * elm is the new separator.
1493 hammer_modify_node_noundo(cursor->trans, new_node);
1494 hammer_modify_node_all(cursor->trans, node);
1495 ondisk = node->ondisk;
1496 elm = &ondisk->elms[split];
1497 bcopy(elm, &new_node->ondisk->elms[0],
1498 (ondisk->count - split + 1) * esize);
1499 new_node->ondisk->count = ondisk->count - split;
1500 new_node->ondisk->parent = parent->node_offset;
1501 new_node->ondisk->type = HAMMER_BTREE_TYPE_INTERNAL;
1502 new_node->ondisk->mirror_tid = ondisk->mirror_tid;
1503 KKASSERT(ondisk->type == new_node->ondisk->type);
1504 hammer_cursor_split_node(node, new_node, split);
1507 * Cleanup the original node. Elm (P) becomes the new boundary,
1508 * its subtree_offset was moved to the new node. If we had created
1509 * a new root its parent pointer may have changed.
1511 elm->internal.subtree_offset = 0;
1512 ondisk->count = split;
1515 * Insert the separator into the parent, fixup the parent's
1516 * reference to the original node, and reference the new node.
1517 * The separator is P.
1519 * Remember that base.count does not include the right-hand boundary.
1521 hammer_modify_node_all(cursor->trans, parent);
1522 ondisk = parent->ondisk;
1523 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS);
1524 parent_elm = &ondisk->elms[parent_index+1];
1525 bcopy(parent_elm, parent_elm + 1,
1526 (ondisk->count - parent_index) * esize);
1527 parent_elm->internal.base = elm->base; /* separator P */
1528 parent_elm->internal.base.btype = new_node->ondisk->type;
1529 parent_elm->internal.subtree_offset = new_node->node_offset;
1530 parent_elm->internal.mirror_tid = new_node->ondisk->mirror_tid;
1532 hammer_modify_node_done(parent);
1533 hammer_cursor_inserted_element(parent, parent_index + 1);
1536 * The children of new_node need their parent pointer set to new_node.
1537 * The children have already been locked by
1538 * hammer_btree_lock_children().
1540 for (i = 0; i < new_node->ondisk->count; ++i) {
1541 elm = &new_node->ondisk->elms[i];
1542 error = btree_set_parent(cursor->trans, new_node, elm);
1544 panic("btree_split_internal: btree-fixup problem");
1547 hammer_modify_node_done(new_node);
1550 * The filesystem's root B-Tree pointer may have to be updated.
1553 hammer_volume_t volume;
1555 volume = hammer_get_root_volume(hmp, &error);
1556 KKASSERT(error == 0);
1558 hammer_modify_volume_field(cursor->trans, volume,
1560 volume->ondisk->vol0_btree_root = parent->node_offset;
1561 hammer_modify_volume_done(volume);
1562 node->ondisk->parent = parent->node_offset;
1563 if (cursor->parent) {
1564 hammer_unlock(&cursor->parent->lock);
1565 hammer_rel_node(cursor->parent);
1567 cursor->parent = parent; /* lock'd and ref'd */
1568 hammer_rel_volume(volume, 0);
1570 hammer_modify_node_done(node);
1573 * Ok, now adjust the cursor depending on which element the original
1574 * index was pointing at. If we are >= the split point the push node
1575 * is now in the new node.
1577 * NOTE: If we are at the split point itself we cannot stay with the
1578 * original node because the push index will point at the right-hand
1579 * boundary, which is illegal.
1581 * NOTE: The cursor's parent or parent_index must be adjusted for
1582 * the case where a new parent (new root) was created, and the case
1583 * where the cursor is now pointing at the split node.
1585 if (cursor->index >= split) {
1586 cursor->parent_index = parent_index + 1;
1587 cursor->index -= split;
1588 hammer_unlock(&cursor->node->lock);
1589 hammer_rel_node(cursor->node);
1590 cursor->node = new_node; /* locked and ref'd */
1592 cursor->parent_index = parent_index;
1593 hammer_unlock(&new_node->lock);
1594 hammer_rel_node(new_node);
1598 * Fixup left and right bounds
1600 parent_elm = &parent->ondisk->elms[cursor->parent_index];
1601 cursor->left_bound = &parent_elm[0].internal.base;
1602 cursor->right_bound = &parent_elm[1].internal.base;
1603 KKASSERT(hammer_btree_cmp(cursor->left_bound,
1604 &cursor->node->ondisk->elms[0].internal.base) <= 0);
1605 KKASSERT(hammer_btree_cmp(cursor->right_bound,
1606 &cursor->node->ondisk->elms[cursor->node->ondisk->count].internal.base) >= 0);
1609 hammer_btree_unlock_children(&locklist);
1610 hammer_cursor_downgrade(cursor);
1615 * Same as the above, but splits a full leaf node.
1621 btree_split_leaf(hammer_cursor_t cursor)
1623 hammer_node_ondisk_t ondisk;
1624 hammer_node_t parent;
1627 hammer_node_t new_leaf;
1628 hammer_btree_elm_t elm;
1629 hammer_btree_elm_t parent_elm;
1630 hammer_base_elm_t mid_boundary;
1635 const size_t esize = sizeof(*elm);
1637 if ((error = hammer_cursor_upgrade(cursor)) != 0)
1639 ++hammer_stats_btree_splits;
1641 KKASSERT(hammer_btree_cmp(cursor->left_bound,
1642 &cursor->node->ondisk->elms[0].leaf.base) <= 0);
1643 KKASSERT(hammer_btree_cmp(cursor->right_bound,
1644 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0);
1647 * Calculate the split point. If the insertion point will be on
1648 * the left-hand side adjust the split point to give the right
1649 * hand side one additional node.
1651 * Spikes are made up of two leaf elements which cannot be
1654 leaf = cursor->node;
1655 ondisk = leaf->ondisk;
1656 split = (ondisk->count + 1) / 2;
1657 if (cursor->index <= split)
1662 elm = &ondisk->elms[split];
1664 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm[-1].leaf.base) <= 0);
1665 KKASSERT(hammer_btree_cmp(cursor->left_bound, &elm->leaf.base) <= 0);
1666 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm->leaf.base) > 0);
1667 KKASSERT(hammer_btree_cmp(cursor->right_bound, &elm[1].leaf.base) > 0);
1670 * If we are at the root of the tree, create a new root node with
1671 * 1 element and split normally. Avoid making major modifications
1672 * until we know the whole operation will work.
1674 if (ondisk->parent == 0) {
1675 parent = hammer_alloc_btree(cursor->trans, &error);
1678 hammer_lock_ex(&parent->lock);
1679 hammer_modify_node_noundo(cursor->trans, parent);
1680 ondisk = parent->ondisk;
1683 ondisk->mirror_tid = leaf->ondisk->mirror_tid;
1684 ondisk->type = HAMMER_BTREE_TYPE_INTERNAL;
1685 ondisk->elms[0].base = hmp->root_btree_beg;
1686 ondisk->elms[0].base.btype = leaf->ondisk->type;
1687 ondisk->elms[0].internal.subtree_offset = leaf->node_offset;
1688 ondisk->elms[1].base = hmp->root_btree_end;
1689 /* ondisk->elms[1].base.btype = not used */
1690 hammer_modify_node_done(parent);
1692 parent_index = 0; /* insertion point in parent */
1695 parent = cursor->parent;
1696 parent_index = cursor->parent_index;
1700 * Split leaf into new_leaf at the split point. Select a separator
1701 * value in-between the two leafs but with a bent towards the right
1702 * leaf since comparisons use an 'elm >= separator' inequality.
1711 new_leaf = hammer_alloc_btree(cursor->trans, &error);
1712 if (new_leaf == NULL) {
1714 hammer_unlock(&parent->lock);
1715 hammer_delete_node(cursor->trans, parent);
1716 hammer_rel_node(parent);
1720 hammer_lock_ex(&new_leaf->lock);
1723 * Create the new node and copy the leaf elements from the split
1724 * point on to the new node.
1726 hammer_modify_node_all(cursor->trans, leaf);
1727 hammer_modify_node_noundo(cursor->trans, new_leaf);
1728 ondisk = leaf->ondisk;
1729 elm = &ondisk->elms[split];
1730 bcopy(elm, &new_leaf->ondisk->elms[0], (ondisk->count - split) * esize);
1731 new_leaf->ondisk->count = ondisk->count - split;
1732 new_leaf->ondisk->parent = parent->node_offset;
1733 new_leaf->ondisk->type = HAMMER_BTREE_TYPE_LEAF;
1734 new_leaf->ondisk->mirror_tid = ondisk->mirror_tid;
1735 KKASSERT(ondisk->type == new_leaf->ondisk->type);
1736 hammer_modify_node_done(new_leaf);
1737 hammer_cursor_split_node(leaf, new_leaf, split);
1740 * Cleanup the original node. Because this is a leaf node and
1741 * leaf nodes do not have a right-hand boundary, there
1742 * aren't any special edge cases to clean up. We just fixup the
1745 ondisk->count = split;
1748 * Insert the separator into the parent, fixup the parent's
1749 * reference to the original node, and reference the new node.
1750 * The separator is P.
1752 * Remember that base.count does not include the right-hand boundary.
1753 * We are copying parent_index+1 to parent_index+2, not +0 to +1.
1755 hammer_modify_node_all(cursor->trans, parent);
1756 ondisk = parent->ondisk;
1757 KKASSERT(split != 0);
1758 KKASSERT(ondisk->count != HAMMER_BTREE_INT_ELMS);
1759 parent_elm = &ondisk->elms[parent_index+1];
1760 bcopy(parent_elm, parent_elm + 1,
1761 (ondisk->count - parent_index) * esize);
1763 hammer_make_separator(&elm[-1].base, &elm[0].base, &parent_elm->base);
1764 parent_elm->internal.base.btype = new_leaf->ondisk->type;
1765 parent_elm->internal.subtree_offset = new_leaf->node_offset;
1766 parent_elm->internal.mirror_tid = new_leaf->ondisk->mirror_tid;
1767 mid_boundary = &parent_elm->base;
1769 hammer_modify_node_done(parent);
1770 hammer_cursor_inserted_element(parent, parent_index + 1);
1773 * The filesystem's root B-Tree pointer may have to be updated.
1776 hammer_volume_t volume;
1778 volume = hammer_get_root_volume(hmp, &error);
1779 KKASSERT(error == 0);
1781 hammer_modify_volume_field(cursor->trans, volume,
1783 volume->ondisk->vol0_btree_root = parent->node_offset;
1784 hammer_modify_volume_done(volume);
1785 leaf->ondisk->parent = parent->node_offset;
1786 if (cursor->parent) {
1787 hammer_unlock(&cursor->parent->lock);
1788 hammer_rel_node(cursor->parent);
1790 cursor->parent = parent; /* lock'd and ref'd */
1791 hammer_rel_volume(volume, 0);
1793 hammer_modify_node_done(leaf);
1796 * Ok, now adjust the cursor depending on which element the original
1797 * index was pointing at. If we are >= the split point the push node
1798 * is now in the new node.
1800 * NOTE: If we are at the split point itself we need to select the
1801 * old or new node based on where key_beg's insertion point will be.
1802 * If we pick the wrong side the inserted element will wind up in
1803 * the wrong leaf node and outside that node's bounds.
1805 if (cursor->index > split ||
1806 (cursor->index == split &&
1807 hammer_btree_cmp(&cursor->key_beg, mid_boundary) >= 0)) {
1808 cursor->parent_index = parent_index + 1;
1809 cursor->index -= split;
1810 hammer_unlock(&cursor->node->lock);
1811 hammer_rel_node(cursor->node);
1812 cursor->node = new_leaf;
1814 cursor->parent_index = parent_index;
1815 hammer_unlock(&new_leaf->lock);
1816 hammer_rel_node(new_leaf);
1820 * Fixup left and right bounds
1822 parent_elm = &parent->ondisk->elms[cursor->parent_index];
1823 cursor->left_bound = &parent_elm[0].internal.base;
1824 cursor->right_bound = &parent_elm[1].internal.base;
1827 * Assert that the bounds are correct.
1829 KKASSERT(hammer_btree_cmp(cursor->left_bound,
1830 &cursor->node->ondisk->elms[0].leaf.base) <= 0);
1831 KKASSERT(hammer_btree_cmp(cursor->right_bound,
1832 &cursor->node->ondisk->elms[cursor->node->ondisk->count-1].leaf.base) > 0);
1833 KKASSERT(hammer_btree_cmp(cursor->left_bound, &cursor->key_beg) <= 0);
1834 KKASSERT(hammer_btree_cmp(cursor->right_bound, &cursor->key_beg) > 0);
1837 hammer_cursor_downgrade(cursor);
1844 * Recursively correct the right-hand boundary's create_tid to (tid) as
1845 * long as the rest of the key matches. We have to recurse upward in
1846 * the tree as well as down the left side of each parent's right node.
1848 * Return EDEADLK if we were only partially successful, forcing the caller
1849 * to try again. The original cursor is not modified. This routine can
1850 * also fail with EDEADLK if it is forced to throw away a portion of its
1853 * The caller must pass a downgraded cursor to us (otherwise we can't dup it).
1856 TAILQ_ENTRY(hammer_rhb) entry;
1861 TAILQ_HEAD(hammer_rhb_list, hammer_rhb);
1864 hammer_btree_correct_rhb(hammer_cursor_t cursor, hammer_tid_t tid)
1866 struct hammer_rhb_list rhb_list;
1867 hammer_base_elm_t elm;
1868 hammer_node_t orig_node;
1869 struct hammer_rhb *rhb;
1873 TAILQ_INIT(&rhb_list);
1876 * Save our position so we can restore it on return. This also
1877 * gives us a stable 'elm'.
1879 orig_node = cursor->node;
1880 hammer_ref_node(orig_node);
1881 hammer_lock_sh(&orig_node->lock);
1882 orig_index = cursor->index;
1883 elm = &orig_node->ondisk->elms[orig_index].base;
1886 * Now build a list of parents going up, allocating a rhb
1887 * structure for each one.
1889 while (cursor->parent) {
1891 * Stop if we no longer have any right-bounds to fix up
1893 if (elm->obj_id != cursor->right_bound->obj_id ||
1894 elm->rec_type != cursor->right_bound->rec_type ||
1895 elm->key != cursor->right_bound->key) {
1900 * Stop if the right-hand bound's create_tid does not
1901 * need to be corrected.
1903 if (cursor->right_bound->create_tid >= tid)
1906 rhb = kmalloc(sizeof(*rhb), M_HAMMER, M_WAITOK|M_ZERO);
1907 rhb->node = cursor->parent;
1908 rhb->index = cursor->parent_index;
1909 hammer_ref_node(rhb->node);
1910 hammer_lock_sh(&rhb->node->lock);
1911 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry);
1913 hammer_cursor_up(cursor);
1917 * now safely adjust the right hand bound for each rhb. This may
1918 * also require taking the right side of the tree and iterating down
1922 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) {
1923 error = hammer_cursor_seek(cursor, rhb->node, rhb->index);
1926 TAILQ_REMOVE(&rhb_list, rhb, entry);
1927 hammer_unlock(&rhb->node->lock);
1928 hammer_rel_node(rhb->node);
1929 kfree(rhb, M_HAMMER);
1931 switch (cursor->node->ondisk->type) {
1932 case HAMMER_BTREE_TYPE_INTERNAL:
1934 * Right-boundary for parent at internal node
1935 * is one element to the right of the element whos
1936 * right boundary needs adjusting. We must then
1937 * traverse down the left side correcting any left
1938 * bounds (which may now be too far to the left).
1941 error = hammer_btree_correct_lhb(cursor, tid);
1944 panic("hammer_btree_correct_rhb(): Bad node type");
1953 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) {
1954 TAILQ_REMOVE(&rhb_list, rhb, entry);
1955 hammer_unlock(&rhb->node->lock);
1956 hammer_rel_node(rhb->node);
1957 kfree(rhb, M_HAMMER);
1959 error = hammer_cursor_seek(cursor, orig_node, orig_index);
1960 hammer_unlock(&orig_node->lock);
1961 hammer_rel_node(orig_node);
1966 * Similar to rhb (in fact, rhb calls lhb), but corrects the left hand
1967 * bound going downward starting at the current cursor position.
1969 * This function does not restore the cursor after use.
1972 hammer_btree_correct_lhb(hammer_cursor_t cursor, hammer_tid_t tid)
1974 struct hammer_rhb_list rhb_list;
1975 hammer_base_elm_t elm;
1976 hammer_base_elm_t cmp;
1977 struct hammer_rhb *rhb;
1980 TAILQ_INIT(&rhb_list);
1982 cmp = &cursor->node->ondisk->elms[cursor->index].base;
1985 * Record the node and traverse down the left-hand side for all
1986 * matching records needing a boundary correction.
1990 rhb = kmalloc(sizeof(*rhb), M_HAMMER, M_WAITOK|M_ZERO);
1991 rhb->node = cursor->node;
1992 rhb->index = cursor->index;
1993 hammer_ref_node(rhb->node);
1994 hammer_lock_sh(&rhb->node->lock);
1995 TAILQ_INSERT_HEAD(&rhb_list, rhb, entry);
1997 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) {
1999 * Nothing to traverse down if we are at the right
2000 * boundary of an internal node.
2002 if (cursor->index == cursor->node->ondisk->count)
2005 elm = &cursor->node->ondisk->elms[cursor->index].base;
2006 if (elm->btype == HAMMER_BTREE_TYPE_RECORD)
2008 panic("Illegal leaf record type %02x", elm->btype);
2010 error = hammer_cursor_down(cursor);
2014 elm = &cursor->node->ondisk->elms[cursor->index].base;
2015 if (elm->obj_id != cmp->obj_id ||
2016 elm->rec_type != cmp->rec_type ||
2017 elm->key != cmp->key) {
2020 if (elm->create_tid >= tid)
2026 * Now we can safely adjust the left-hand boundary from the bottom-up.
2027 * The last element we remove from the list is the caller's right hand
2028 * boundary, which must also be adjusted.
2030 while (error == 0 && (rhb = TAILQ_FIRST(&rhb_list)) != NULL) {
2031 error = hammer_cursor_seek(cursor, rhb->node, rhb->index);
2034 TAILQ_REMOVE(&rhb_list, rhb, entry);
2035 hammer_unlock(&rhb->node->lock);
2036 hammer_rel_node(rhb->node);
2037 kfree(rhb, M_HAMMER);
2039 elm = &cursor->node->ondisk->elms[cursor->index].base;
2040 if (cursor->node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) {
2041 hammer_modify_node(cursor->trans, cursor->node,
2043 sizeof(elm->create_tid));
2044 elm->create_tid = tid;
2045 hammer_modify_node_done(cursor->node);
2047 panic("hammer_btree_correct_lhb(): Bad element type");
2054 while ((rhb = TAILQ_FIRST(&rhb_list)) != NULL) {
2055 TAILQ_REMOVE(&rhb_list, rhb, entry);
2056 hammer_unlock(&rhb->node->lock);
2057 hammer_rel_node(rhb->node);
2058 kfree(rhb, M_HAMMER);
2066 * Attempt to remove the locked, empty or want-to-be-empty B-Tree node at
2067 * (cursor->node). Returns 0 on success, EDEADLK if we could not complete
2068 * the operation due to a deadlock, or some other error.
2070 * This routine is always called with an empty, locked leaf but may recurse
2071 * into want-to-be-empty parents as part of its operation.
2073 * It should also be noted that when removing empty leaves we must be sure
2074 * to test and update mirror_tid because another thread may have deadlocked
2075 * against us (or someone) trying to propagate it up and cannot retry once
2076 * the node has been deleted.
2078 * On return the cursor may end up pointing to an internal node, suitable
2079 * for further iteration but not for an immediate insertion or deletion.
2082 btree_remove(hammer_cursor_t cursor)
2084 hammer_node_ondisk_t ondisk;
2085 hammer_btree_elm_t elm;
2087 hammer_node_t parent;
2088 const int esize = sizeof(*elm);
2091 node = cursor->node;
2094 * When deleting the root of the filesystem convert it to
2095 * an empty leaf node. Internal nodes cannot be empty.
2097 ondisk = node->ondisk;
2098 if (ondisk->parent == 0) {
2099 KKASSERT(cursor->parent == NULL);
2100 hammer_modify_node_all(cursor->trans, node);
2101 KKASSERT(ondisk == node->ondisk);
2102 ondisk->type = HAMMER_BTREE_TYPE_LEAF;
2104 hammer_modify_node_done(node);
2109 parent = cursor->parent;
2110 hammer_cursor_removed_node(node, parent, cursor->parent_index);
2113 * Attempt to remove the parent's reference to the child. If the
2114 * parent would become empty we have to recurse. If we fail we
2115 * leave the parent pointing to an empty leaf node.
2117 if (parent->ondisk->count == 1) {
2119 * This special cursor_up_locked() call leaves the original
2120 * node exclusively locked and referenced, leaves the
2121 * original parent locked (as the new node), and locks the
2122 * new parent. It can return EDEADLK.
2124 error = hammer_cursor_up_locked(cursor);
2126 error = btree_remove(cursor);
2128 hammer_modify_node_all(cursor->trans, node);
2129 ondisk = node->ondisk;
2130 ondisk->type = HAMMER_BTREE_TYPE_DELETED;
2132 hammer_modify_node_done(node);
2133 hammer_flush_node(node);
2134 hammer_delete_node(cursor->trans, node);
2136 kprintf("Warning: BTREE_REMOVE: Defering "
2137 "parent removal1 @ %016llx, skipping\n",
2140 hammer_unlock(&node->lock);
2141 hammer_rel_node(node);
2143 kprintf("Warning: BTREE_REMOVE: Defering parent "
2144 "removal2 @ %016llx, skipping\n",
2148 KKASSERT(parent->ondisk->count > 1);
2150 hammer_modify_node_all(cursor->trans, parent);
2151 ondisk = parent->ondisk;
2152 KKASSERT(ondisk->type == HAMMER_BTREE_TYPE_INTERNAL);
2154 elm = &ondisk->elms[cursor->parent_index];
2155 KKASSERT(elm->internal.subtree_offset == node->node_offset);
2156 KKASSERT(ondisk->count > 0);
2159 * We must retain the highest mirror_tid. The deleted
2160 * range is now encompassed by the element to the left.
2161 * If we are already at the left edge the new left edge
2162 * inherits mirror_tid.
2164 * Note that bounds of the parent to our parent may create
2165 * a gap to the left of our left-most node or to the right
2166 * of our right-most node. The gap is silently included
2167 * in the mirror_tid's area of effect from the point of view
2170 if (cursor->parent_index) {
2171 if (elm[-1].internal.mirror_tid <
2172 elm[0].internal.mirror_tid) {
2173 elm[-1].internal.mirror_tid =
2174 elm[0].internal.mirror_tid;
2177 if (elm[1].internal.mirror_tid <
2178 elm[0].internal.mirror_tid) {
2179 elm[1].internal.mirror_tid =
2180 elm[0].internal.mirror_tid;
2185 * Delete the subtree reference in the parent
2187 bcopy(&elm[1], &elm[0],
2188 (ondisk->count - cursor->parent_index) * esize);
2190 hammer_modify_node_done(parent);
2191 hammer_cursor_deleted_element(parent, cursor->parent_index);
2192 hammer_flush_node(node);
2193 hammer_delete_node(cursor->trans, node);
2196 * cursor->node is invalid, cursor up to make the cursor
2199 error = hammer_cursor_up(cursor);
2205 * Propagate cursor->trans->tid up the B-Tree starting at the current
2206 * cursor position using pseudofs info gleaned from the passed inode.
2208 * The passed inode has no relationship to the cursor position other
2209 * then being in the same pseudofs as the insertion or deletion we
2210 * are propagating the mirror_tid for.
2213 hammer_btree_do_propagation(hammer_cursor_t cursor,
2214 hammer_pseudofs_inmem_t pfsm,
2215 hammer_btree_leaf_elm_t leaf)
2217 hammer_cursor_t ncursor;
2218 hammer_tid_t mirror_tid;
2222 * We only propagate the mirror_tid up if we are in master or slave
2223 * mode. We do not bother if we are in no-mirror mode.
2225 * If pfsm is NULL we propagate (from mirror_write).
2228 pfsm->pfsd.master_id < 0 &&
2229 (pfsm->pfsd.mirror_flags & HAMMER_PFSD_SLAVE) == 0) {
2234 * This is a bit of a hack because we cannot deadlock or return
2235 * EDEADLK here. The related operation has already completed and
2236 * we must propagate the mirror_tid now regardless.
2238 * Generate a new cursor which inherits the original's locks and
2239 * unlock the original. Use the new cursor to propagate the
2240 * mirror_tid. Then clean up the new cursor and reacquire locks
2243 * hammer_dup_cursor() cannot dup locks. The dup inherits the
2244 * original's locks and the original is tracked and must be
2247 mirror_tid = cursor->node->ondisk->mirror_tid;
2248 KKASSERT(mirror_tid != 0);
2249 ncursor = hammer_push_cursor(cursor);
2250 error = hammer_btree_mirror_propagate(ncursor, mirror_tid);
2251 KKASSERT(error == 0);
2252 hammer_pop_cursor(cursor, ncursor);
2257 * Propagate a mirror TID update upwards through the B-Tree to the root.
2259 * A locked internal node must be passed in. The node will remain locked
2262 * This function syncs mirror_tid at the specified internal node's element,
2263 * adjusts the node's aggregation mirror_tid, and then recurses upwards.
2266 hammer_btree_mirror_propagate(hammer_cursor_t cursor, hammer_tid_t mirror_tid)
2268 hammer_btree_internal_elm_t elm;
2273 error = hammer_cursor_up(cursor);
2275 error = hammer_cursor_upgrade(cursor);
2276 while (error == EDEADLK) {
2277 hammer_recover_cursor(cursor);
2278 error = hammer_cursor_upgrade(cursor);
2282 node = cursor->node;
2283 KKASSERT (node->ondisk->type == HAMMER_BTREE_TYPE_INTERNAL);
2286 * Adjust the node's element
2288 elm = &node->ondisk->elms[cursor->index].internal;
2289 if (elm->mirror_tid >= mirror_tid)
2291 hammer_modify_node(cursor->trans, node, &elm->mirror_tid,
2292 sizeof(elm->mirror_tid));
2293 elm->mirror_tid = mirror_tid;
2294 hammer_modify_node_done(node);
2297 * Adjust the node's mirror_tid aggregator
2299 if (node->ondisk->mirror_tid >= mirror_tid)
2301 hammer_modify_node_field(cursor->trans, node, mirror_tid);
2302 node->ondisk->mirror_tid = mirror_tid;
2303 hammer_modify_node_done(node);
2305 if (error == ENOENT)
2311 hammer_btree_get_parent(hammer_node_t node, int *parent_indexp, int *errorp,
2314 hammer_node_t parent;
2315 hammer_btree_elm_t elm;
2321 parent = hammer_get_node(node->hmp, node->ondisk->parent, 0, errorp);
2323 KKASSERT(parent == NULL);
2326 KKASSERT ((parent->flags & HAMMER_NODE_DELETED) == 0);
2331 if (try_exclusive) {
2332 if (hammer_lock_ex_try(&parent->lock)) {
2333 hammer_rel_node(parent);
2338 hammer_lock_sh(&parent->lock);
2342 * Figure out which element in the parent is pointing to the
2345 if (node->ondisk->count) {
2346 i = hammer_btree_search_node(&node->ondisk->elms[0].base,
2351 while (i < parent->ondisk->count) {
2352 elm = &parent->ondisk->elms[i];
2353 if (elm->internal.subtree_offset == node->node_offset)
2357 if (i == parent->ondisk->count) {
2358 hammer_unlock(&parent->lock);
2359 panic("Bad B-Tree link: parent %p node %p\n", parent, node);
2362 KKASSERT(*errorp == 0);
2367 * The element (elm) has been moved to a new internal node (node).
2369 * If the element represents a pointer to an internal node that node's
2370 * parent must be adjusted to the element's new location.
2372 * XXX deadlock potential here with our exclusive locks
2375 btree_set_parent(hammer_transaction_t trans, hammer_node_t node,
2376 hammer_btree_elm_t elm)
2378 hammer_node_t child;
2383 switch(elm->base.btype) {
2384 case HAMMER_BTREE_TYPE_INTERNAL:
2385 case HAMMER_BTREE_TYPE_LEAF:
2386 child = hammer_get_node(node->hmp, elm->internal.subtree_offset,
2389 hammer_modify_node_field(trans, child, parent);
2390 child->ondisk->parent = node->node_offset;
2391 hammer_modify_node_done(child);
2392 hammer_rel_node(child);
2402 * Exclusively lock all the children of node. This is used by the split
2403 * code to prevent anyone from accessing the children of a cursor node
2404 * while we fix-up its parent offset.
2406 * If we don't lock the children we can really mess up cursors which block
2407 * trying to cursor-up into our node.
2409 * On failure EDEADLK (or some other error) is returned. If a deadlock
2410 * error is returned the cursor is adjusted to block on termination.
2413 hammer_btree_lock_children(hammer_cursor_t cursor,
2414 struct hammer_node_locklist **locklistp)
2417 hammer_node_locklist_t item;
2418 hammer_node_ondisk_t ondisk;
2419 hammer_btree_elm_t elm;
2420 hammer_node_t child;
2424 node = cursor->node;
2425 ondisk = node->ondisk;
2429 * We really do not want to block on I/O with exclusive locks held,
2430 * pre-get the children before trying to lock the mess.
2432 for (i = 0; i < ondisk->count; ++i) {
2433 ++hammer_stats_btree_elements;
2434 elm = &ondisk->elms[i];
2435 if (elm->base.btype != HAMMER_BTREE_TYPE_LEAF &&
2436 elm->base.btype != HAMMER_BTREE_TYPE_INTERNAL) {
2439 child = hammer_get_node(node->hmp,
2440 elm->internal.subtree_offset,
2443 hammer_rel_node(child);
2449 for (i = 0; error == 0 && i < ondisk->count; ++i) {
2450 ++hammer_stats_btree_elements;
2451 elm = &ondisk->elms[i];
2453 switch(elm->base.btype) {
2454 case HAMMER_BTREE_TYPE_INTERNAL:
2455 case HAMMER_BTREE_TYPE_LEAF:
2456 KKASSERT(elm->internal.subtree_offset != 0);
2457 child = hammer_get_node(node->hmp,
2458 elm->internal.subtree_offset,
2466 if (hammer_lock_ex_try(&child->lock) != 0) {
2467 if (cursor->deadlk_node == NULL) {
2468 cursor->deadlk_node = child;
2469 hammer_ref_node(cursor->deadlk_node);
2472 hammer_rel_node(child);
2474 item = kmalloc(sizeof(*item),
2475 M_HAMMER, M_WAITOK);
2476 item->next = *locklistp;
2483 hammer_btree_unlock_children(locklistp);
2489 * Release previously obtained node locks.
2492 hammer_btree_unlock_children(struct hammer_node_locklist **locklistp)
2494 hammer_node_locklist_t item;
2496 while ((item = *locklistp) != NULL) {
2497 *locklistp = item->next;
2498 hammer_unlock(&item->node->lock);
2499 hammer_rel_node(item->node);
2500 kfree(item, M_HAMMER);
2504 /************************************************************************
2505 * MISCELLANIOUS SUPPORT *
2506 ************************************************************************/
2509 * Compare two B-Tree elements, return -N, 0, or +N (e.g. similar to strcmp).
2511 * Note that for this particular function a return value of -1, 0, or +1
2512 * can denote a match if create_tid is otherwise discounted. A create_tid
2513 * of zero is considered to be 'infinity' in comparisons.
2515 * See also hammer_rec_rb_compare() and hammer_rec_cmp() in hammer_object.c.
2518 hammer_btree_cmp(hammer_base_elm_t key1, hammer_base_elm_t key2)
2520 if (key1->localization < key2->localization)
2522 if (key1->localization > key2->localization)
2525 if (key1->obj_id < key2->obj_id)
2527 if (key1->obj_id > key2->obj_id)
2530 if (key1->rec_type < key2->rec_type)
2532 if (key1->rec_type > key2->rec_type)
2535 if (key1->key < key2->key)
2537 if (key1->key > key2->key)
2541 * A create_tid of zero indicates a record which is undeletable
2542 * and must be considered to have a value of positive infinity.
2544 if (key1->create_tid == 0) {
2545 if (key2->create_tid == 0)
2549 if (key2->create_tid == 0)
2551 if (key1->create_tid < key2->create_tid)
2553 if (key1->create_tid > key2->create_tid)
2559 * Test a timestamp against an element to determine whether the
2560 * element is visible. A timestamp of 0 means 'infinity'.
2563 hammer_btree_chkts(hammer_tid_t asof, hammer_base_elm_t base)
2566 if (base->delete_tid)
2570 if (asof < base->create_tid)
2572 if (base->delete_tid && asof >= base->delete_tid)
2578 * Create a separator half way inbetween key1 and key2. For fields just
2579 * one unit apart, the separator will match key2. key1 is on the left-hand
2580 * side and key2 is on the right-hand side.
2582 * key2 must be >= the separator. It is ok for the separator to match key2.
2584 * NOTE: Even if key1 does not match key2, the separator may wind up matching
2587 * NOTE: It might be beneficial to just scrap this whole mess and just
2588 * set the separator to key2.
2590 #define MAKE_SEPARATOR(key1, key2, dest, field) \
2591 dest->field = key1->field + ((key2->field - key1->field + 1) >> 1);
2594 hammer_make_separator(hammer_base_elm_t key1, hammer_base_elm_t key2,
2595 hammer_base_elm_t dest)
2597 bzero(dest, sizeof(*dest));
2599 dest->rec_type = key2->rec_type;
2600 dest->key = key2->key;
2601 dest->obj_id = key2->obj_id;
2602 dest->create_tid = key2->create_tid;
2604 MAKE_SEPARATOR(key1, key2, dest, localization);
2605 if (key1->localization == key2->localization) {
2606 MAKE_SEPARATOR(key1, key2, dest, obj_id);
2607 if (key1->obj_id == key2->obj_id) {
2608 MAKE_SEPARATOR(key1, key2, dest, rec_type);
2609 if (key1->rec_type == key2->rec_type) {
2610 MAKE_SEPARATOR(key1, key2, dest, key);
2612 * Don't bother creating a separator for
2613 * create_tid, which also conveniently avoids
2614 * having to handle the create_tid == 0
2615 * (infinity) case. Just leave create_tid
2618 * Worst case, dest matches key2 exactly,
2619 * which is acceptable.
2626 #undef MAKE_SEPARATOR
2629 * Return whether a generic internal or leaf node is full
2632 btree_node_is_full(hammer_node_ondisk_t node)
2634 switch(node->type) {
2635 case HAMMER_BTREE_TYPE_INTERNAL:
2636 if (node->count == HAMMER_BTREE_INT_ELMS)
2639 case HAMMER_BTREE_TYPE_LEAF:
2640 if (node->count == HAMMER_BTREE_LEAF_ELMS)
2644 panic("illegal btree subtype");
2651 btree_max_elements(u_int8_t type)
2653 if (type == HAMMER_BTREE_TYPE_LEAF)
2654 return(HAMMER_BTREE_LEAF_ELMS);
2655 if (type == HAMMER_BTREE_TYPE_INTERNAL)
2656 return(HAMMER_BTREE_INT_ELMS);
2657 panic("btree_max_elements: bad type %d\n", type);
2662 hammer_print_btree_node(hammer_node_ondisk_t ondisk)
2664 hammer_btree_elm_t elm;
2667 kprintf("node %p count=%d parent=%016llx type=%c\n",
2668 ondisk, ondisk->count, ondisk->parent, ondisk->type);
2671 * Dump both boundary elements if an internal node
2673 if (ondisk->type == HAMMER_BTREE_TYPE_INTERNAL) {
2674 for (i = 0; i <= ondisk->count; ++i) {
2675 elm = &ondisk->elms[i];
2676 hammer_print_btree_elm(elm, ondisk->type, i);
2679 for (i = 0; i < ondisk->count; ++i) {
2680 elm = &ondisk->elms[i];
2681 hammer_print_btree_elm(elm, ondisk->type, i);
2687 hammer_print_btree_elm(hammer_btree_elm_t elm, u_int8_t type, int i)
2690 kprintf("\tobj_id = %016llx\n", elm->base.obj_id);
2691 kprintf("\tkey = %016llx\n", elm->base.key);
2692 kprintf("\tcreate_tid = %016llx\n", elm->base.create_tid);
2693 kprintf("\tdelete_tid = %016llx\n", elm->base.delete_tid);
2694 kprintf("\trec_type = %04x\n", elm->base.rec_type);
2695 kprintf("\tobj_type = %02x\n", elm->base.obj_type);
2696 kprintf("\tbtype = %02x (%c)\n",
2698 (elm->base.btype ? elm->base.btype : '?'));
2699 kprintf("\tlocalization = %02x\n", elm->base.localization);
2702 case HAMMER_BTREE_TYPE_INTERNAL:
2703 kprintf("\tsubtree_off = %016llx\n",
2704 elm->internal.subtree_offset);
2706 case HAMMER_BTREE_TYPE_RECORD:
2707 kprintf("\tdata_offset = %016llx\n", elm->leaf.data_offset);
2708 kprintf("\tdata_len = %08x\n", elm->leaf.data_len);
2709 kprintf("\tdata_crc = %08x\n", elm->leaf.data_crc);