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
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
36 * HAMMER B-Tree index - cursor support routines
40 static int hammer_load_cursor_parent(hammer_cursor_t cursor
, int try_exclusive
);
43 * Initialize a fresh cursor using the B-Tree node cache. If the cache
44 * is not available initialize a fresh cursor at the root of the filesystem.
47 hammer_init_cursor(hammer_transaction_t trans
, hammer_cursor_t cursor
,
48 hammer_node_cache_t cache
, hammer_inode_t ip
)
50 hammer_volume_t volume
;
56 bzero(cursor
, sizeof(*cursor
));
58 cursor
->trans
= trans
;
62 * As the number of inodes queued to the flusher increases we use
63 * time-domain multiplexing to control read vs flush performance.
64 * We have to do it here, before acquiring any ip or node locks,
65 * to avoid deadlocking or excessively delaying the flusher.
67 * The full time period is hammer_tdmux_ticks, typically 1/5 of
70 * inode allocation begins to get restrained at 2/4 the limit
71 * via the "hmrrcm" mechanism in hammer_inode. We want to begin
72 * limiting read activity before that to try to avoid processes
73 * stalling out in "hmrrcm".
75 tticks
= hammer_tdmux_ticks
;
76 if (trans
->type
!= HAMMER_TRANS_FLS
&& tticks
&&
77 hmp
->count_reclaims
> hammer_limit_reclaims
/ tticks
&&
78 hmp
->count_reclaims
> hammer_autoflush
* 2 &&
79 hammer_flusher_running(hmp
)) {
85 * 0 ... xticks ... tticks
87 * rticks is the calculated position, xticks is the demarc
88 * where values below xticks are reserved for the flusher
89 * and values >= to xticks may be used by the frontend.
91 * At least one tick is always made available for the
94 rticks
= (u_int
)ticks
% tticks
;
95 xticks
= hmp
->count_reclaims
* tticks
/ hammer_limit_reclaims
;
98 * Ensure rticks and xticks are stable
101 if (rticks
< xticks
) {
102 if (hammer_debug_general
& 0x0004)
103 hdkprintf("rt %3u, xt %3u, tt %3u\n",
104 rticks
, xticks
, tticks
);
105 tsleep(&dummy
, 0, "htdmux", xticks
- rticks
);
110 * If the cursor operation is on behalf of an inode, lock
113 * When acquiring a shared lock on an inode on which the backend
114 * flusher deadlocked, wait up to hammer_tdmux_ticks (1 second)
115 * for the deadlock to clear.
117 if ((cursor
->ip
= ip
) != NULL
) {
118 ++ip
->cursor_ip_refs
;
119 if (trans
->type
== HAMMER_TRANS_FLS
) {
120 hammer_lock_ex(&ip
->lock
);
123 if (ip
->cursor_exclreq_count
) {
124 tsleep(&ip
->cursor_exclreq_count
, 0,
125 "hstag1", hammer_tdmux_ticks
);
128 hammer_lock_sh(&ip
->lock
);
133 * Step 1 - acquire a locked node from the cache if possible
135 if (cache
&& cache
->node
) {
136 node
= hammer_ref_node_safe(trans
, cache
, &error
);
138 hammer_lock_sh(&node
->lock
);
139 if (node
->flags
& HAMMER_NODE_DELETED
) {
140 hammer_unlock(&node
->lock
);
141 hammer_rel_node(node
);
146 ++hammer_stats_btree_root_iterations
;
149 ++hammer_stats_btree_root_iterations
;
153 * Step 2 - If we couldn't get a node from the cache, get
154 * the one from the root of the filesystem.
156 while (node
== NULL
) {
157 volume
= hammer_get_root_volume(hmp
, &error
);
160 node
= hammer_get_node(trans
, volume
->ondisk
->vol0_btree_root
,
162 hammer_rel_volume(volume
, 0);
166 * When the frontend acquires the root b-tree node while the
167 * backend is deadlocked on it, wait up to hammer_tdmux_ticks
168 * (1 second) for the deadlock to clear.
171 if (node
->cursor_exclreq_count
&&
172 cursor
->trans
->type
!= HAMMER_TRANS_FLS
) {
173 tsleep(&node
->cursor_exclreq_count
, 0,
174 "hstag3", hammer_tdmux_ticks
);
177 hammer_lock_sh(&node
->lock
);
180 * If someone got in before we could lock the node, retry.
182 if (node
->flags
& HAMMER_NODE_DELETED
) {
183 hammer_unlock(&node
->lock
);
184 hammer_rel_node(node
);
188 if (volume
->ondisk
->vol0_btree_root
!= node
->node_offset
) {
189 hammer_unlock(&node
->lock
);
190 hammer_rel_node(node
);
197 * Step 3 - finish initializing the cursor by acquiring the parent
201 error
= hammer_load_cursor_parent(cursor
, 0);
202 KKASSERT(error
== 0);
203 /* if (error) hammer_done_cursor(cursor); */
208 * Normalize a cursor. Sometimes cursors can be left in a state
209 * where node is NULL. If the cursor is in this state, cursor up.
212 hammer_normalize_cursor(hammer_cursor_t cursor
)
214 if (cursor
->node
== NULL
) {
215 KKASSERT(cursor
->parent
!= NULL
);
216 hammer_cursor_up(cursor
);
222 * We are finished with a cursor. We NULL out various fields as sanity
223 * check, in case the structure is inappropriately used afterwords.
226 hammer_done_cursor(hammer_cursor_t cursor
)
230 KKASSERT((cursor
->flags
& HAMMER_CURSOR_TRACKED
) == 0);
231 if (cursor
->parent
) {
232 hammer_unlock(&cursor
->parent
->lock
);
233 hammer_rel_node(cursor
->parent
);
234 cursor
->parent
= NULL
;
237 hammer_unlock(&cursor
->node
->lock
);
238 hammer_rel_node(cursor
->node
);
241 if (cursor
->data_buffer
) {
242 hammer_rel_buffer(cursor
->data_buffer
, 0);
243 cursor
->data_buffer
= NULL
;
245 if ((ip
= cursor
->ip
) != NULL
) {
246 KKASSERT(ip
->cursor_ip_refs
> 0);
247 --ip
->cursor_ip_refs
;
248 hammer_unlock(&ip
->lock
);
252 hammer_rel_mem_record(cursor
->iprec
);
253 cursor
->iprec
= NULL
;
257 * If we deadlocked this node will be referenced. Do a quick
258 * lock/unlock to wait for the deadlock condition to clear.
260 * Maintain exclreq_count / wakeup as necessary to notify new
261 * entrants into ip. We continue to hold the fs_token so our
262 * EDEADLK retry loop should get its chance before another thread
265 if (cursor
->deadlk_node
) {
267 if (ip
&& cursor
->trans
->type
== HAMMER_TRANS_FLS
)
268 ++ip
->cursor_exclreq_count
;
269 ++cursor
->deadlk_node
->cursor_exclreq_count
;
271 hammer_lock_ex_ident(&cursor
->deadlk_node
->lock
, "hmrdlk");
272 hammer_unlock(&cursor
->deadlk_node
->lock
);
274 if (--cursor
->deadlk_node
->cursor_exclreq_count
== 0)
275 wakeup(&cursor
->deadlk_node
->cursor_exclreq_count
);
276 if (ip
&& cursor
->trans
->type
== HAMMER_TRANS_FLS
) {
277 if (--ip
->cursor_exclreq_count
== 0)
278 wakeup(&ip
->cursor_exclreq_count
);
281 hammer_rel_node(cursor
->deadlk_node
);
282 cursor
->deadlk_node
= NULL
;
284 if (cursor
->deadlk_rec
) {
285 hammer_wait_mem_record_ident(cursor
->deadlk_rec
, "hmmdlr");
286 hammer_rel_mem_record(cursor
->deadlk_rec
);
287 cursor
->deadlk_rec
= NULL
;
292 cursor
->left_bound
= NULL
;
293 cursor
->right_bound
= NULL
;
294 cursor
->trans
= NULL
;
298 * Upgrade cursor->node and cursor->parent to exclusive locks. This
299 * function can return EDEADLK.
301 * The lock must already be either held shared or already held exclusively
304 * We upgrade the parent first as it is the most likely to collide first
305 * with the downward traversal that the frontend typically does.
307 * If we fail to upgrade the lock and cursor->deadlk_node is NULL,
308 * we add another reference to the node that failed and set
309 * cursor->deadlk_node so hammer_done_cursor() can block on it.
312 hammer_cursor_upgrade(hammer_cursor_t cursor
)
316 if (cursor
->parent
) {
317 error
= hammer_lock_upgrade(&cursor
->parent
->lock
, 1);
318 if (error
&& cursor
->deadlk_node
== NULL
) {
319 cursor
->deadlk_node
= cursor
->parent
;
320 hammer_ref_node(cursor
->deadlk_node
);
326 error
= hammer_lock_upgrade(&cursor
->node
->lock
, 1);
327 if (error
&& cursor
->deadlk_node
== NULL
) {
328 cursor
->deadlk_node
= cursor
->node
;
329 hammer_ref_node(cursor
->deadlk_node
);
333 error
= hammer_lock_upgrade(&cursor
->node
->lock
, 1);
334 if (error
&& cursor
->deadlk_node
== NULL
) {
335 cursor
->deadlk_node
= cursor
->node
;
336 hammer_ref_node(cursor
->deadlk_node
);
337 } else if (error
== 0 && cursor
->parent
) {
338 error
= hammer_lock_upgrade(&cursor
->parent
->lock
, 1);
339 if (error
&& cursor
->deadlk_node
== NULL
) {
340 cursor
->deadlk_node
= cursor
->parent
;
341 hammer_ref_node(cursor
->deadlk_node
);
349 hammer_cursor_upgrade_node(hammer_cursor_t cursor
)
353 error
= hammer_lock_upgrade(&cursor
->node
->lock
, 1);
354 if (error
&& cursor
->deadlk_node
== NULL
) {
355 cursor
->deadlk_node
= cursor
->node
;
356 hammer_ref_node(cursor
->deadlk_node
);
362 * Downgrade cursor->node and cursor->parent to shared locks.
365 hammer_cursor_downgrade(hammer_cursor_t cursor
)
367 if (hammer_lock_excl_owned(&cursor
->node
->lock
, curthread
))
368 hammer_lock_downgrade(&cursor
->node
->lock
, 1);
369 if (cursor
->parent
&&
370 hammer_lock_excl_owned(&cursor
->parent
->lock
, curthread
)) {
371 hammer_lock_downgrade(&cursor
->parent
->lock
, 1);
376 * Upgrade and downgrade pairs of cursors. This is used by the dedup
377 * code which must deal with two cursors. A special function is needed
378 * because some of the nodes may be shared between the two cursors,
379 * resulting in share counts > 1 which will normally cause an upgrade
384 collect_node(hammer_node_t
*array
, int *counts
, int n
, hammer_node_t node
)
388 for (i
= 0; i
< n
; ++i
) {
389 if (array
[i
] == node
)
403 hammer_cursor_upgrade2(hammer_cursor_t cursor1
, hammer_cursor_t cursor2
)
405 hammer_node_t nodes
[4];
411 n
= collect_node(nodes
, counts
, 0, cursor1
->node
);
413 n
= collect_node(nodes
, counts
, n
, cursor1
->parent
);
414 n
= collect_node(nodes
, counts
, n
, cursor2
->node
);
416 n
= collect_node(nodes
, counts
, n
, cursor2
->parent
);
419 for (i
= 0; i
< n
; ++i
) {
420 error
= hammer_lock_upgrade(&nodes
[i
]->lock
, counts
[i
]);
426 hammer_lock_downgrade(&nodes
[i
]->lock
, counts
[i
]);
432 hammer_cursor_downgrade2(hammer_cursor_t cursor1
, hammer_cursor_t cursor2
)
434 hammer_node_t nodes
[4];
439 n
= collect_node(nodes
, counts
, 0, cursor1
->node
);
441 n
= collect_node(nodes
, counts
, n
, cursor1
->parent
);
442 n
= collect_node(nodes
, counts
, n
, cursor2
->node
);
444 n
= collect_node(nodes
, counts
, n
, cursor2
->parent
);
446 for (i
= 0; i
< n
; ++i
)
447 hammer_lock_downgrade(&nodes
[i
]->lock
, counts
[i
]);
451 * Seek the cursor to the specified node and index.
453 * The caller must ref the node prior to calling this routine and release
454 * it after it returns. If the seek succeeds the cursor will gain its own
458 hammer_cursor_seek(hammer_cursor_t cursor
, hammer_node_t node
, int index
)
462 hammer_cursor_downgrade(cursor
);
465 if (cursor
->node
!= node
) {
466 hammer_unlock(&cursor
->node
->lock
);
467 hammer_rel_node(cursor
->node
);
469 hammer_ref_node(node
);
470 hammer_lock_sh(&node
->lock
);
471 KKASSERT ((node
->flags
& HAMMER_NODE_DELETED
) == 0);
473 if (cursor
->parent
) {
474 hammer_unlock(&cursor
->parent
->lock
);
475 hammer_rel_node(cursor
->parent
);
476 cursor
->parent
= NULL
;
477 cursor
->parent_index
= 0;
479 error
= hammer_load_cursor_parent(cursor
, 0);
481 cursor
->index
= index
;
486 * Load the parent of cursor->node into cursor->parent.
490 hammer_load_cursor_parent(hammer_cursor_t cursor
, int try_exclusive
)
493 hammer_node_t parent
;
495 hammer_btree_elm_t elm
;
499 hmp
= cursor
->trans
->hmp
;
501 if (cursor
->node
->ondisk
->parent
) {
503 parent
= hammer_btree_get_parent(cursor
->trans
, node
,
505 &error
, try_exclusive
);
507 elm
= &parent
->ondisk
->elms
[parent_index
];
508 cursor
->parent
= parent
;
509 cursor
->parent_index
= parent_index
;
510 cursor
->left_bound
= &elm
[0].internal
.base
;
511 cursor
->right_bound
= &elm
[1].internal
.base
;
514 cursor
->parent
= NULL
;
515 cursor
->parent_index
= 0;
516 cursor
->left_bound
= &hmp
->root_btree_beg
;
517 cursor
->right_bound
= &hmp
->root_btree_end
;
524 * Cursor up to our parent node. Return ENOENT if we are at the root of
528 hammer_cursor_up(hammer_cursor_t cursor
)
532 hammer_cursor_downgrade(cursor
);
535 * If the parent is NULL we are at the root of the B-Tree and
538 if (cursor
->parent
== NULL
)
542 * Set the node to its parent.
544 hammer_unlock(&cursor
->node
->lock
);
545 hammer_rel_node(cursor
->node
);
546 cursor
->node
= cursor
->parent
;
547 cursor
->index
= cursor
->parent_index
;
548 cursor
->parent
= NULL
;
549 cursor
->parent_index
= 0;
551 error
= hammer_load_cursor_parent(cursor
, 0);
556 * Special cursor up given a locked cursor. The orignal node is not
557 * unlocked or released and the cursor is not downgraded.
559 * This function can fail with EDEADLK.
561 * This function is only run when recursively deleting parent nodes
562 * to get rid of an empty leaf.
565 hammer_cursor_up_locked(hammer_cursor_t cursor
)
572 * If the parent is NULL we are at the root of the B-Tree and
575 if (cursor
->parent
== NULL
)
579 save_index
= cursor
->index
;
582 * Set the node to its parent.
584 cursor
->node
= cursor
->parent
;
585 cursor
->index
= cursor
->parent_index
;
586 cursor
->parent
= NULL
;
587 cursor
->parent_index
= 0;
590 * load the new parent, attempt to exclusively lock it. Note that
591 * we are still holding the old parent (now cursor->node) exclusively
594 * This can return EDEADLK. Undo the operation on any error. These
595 * up sequences can occur during iterations so be sure to restore
598 error
= hammer_load_cursor_parent(cursor
, 1);
600 cursor
->parent
= cursor
->node
;
601 cursor
->parent_index
= cursor
->index
;
603 cursor
->index
= save_index
;
610 * Cursor down through the current node, which must be an internal node.
612 * This routine adjusts the cursor and sets index to 0.
615 hammer_cursor_down(hammer_cursor_t cursor
)
618 hammer_btree_elm_t elm
;
622 * The current node becomes the current parent
624 hammer_cursor_downgrade(cursor
);
626 KKASSERT(cursor
->index
>= 0 && cursor
->index
< node
->ondisk
->count
);
627 if (cursor
->parent
) {
628 hammer_unlock(&cursor
->parent
->lock
);
629 hammer_rel_node(cursor
->parent
);
631 cursor
->parent
= node
;
632 cursor
->parent_index
= cursor
->index
;
637 * Extract element to push into at (node,index), set bounds.
639 elm
= &node
->ondisk
->elms
[cursor
->parent_index
];
642 * Ok, push down into elm of an internal node.
644 KKASSERT(node
->ondisk
->type
== HAMMER_BTREE_TYPE_INTERNAL
);
645 KKASSERT(elm
->internal
.subtree_offset
!= 0);
646 cursor
->left_bound
= &elm
[0].internal
.base
;
647 cursor
->right_bound
= &elm
[1].internal
.base
;
648 node
= hammer_get_node(cursor
->trans
,
649 elm
->internal
.subtree_offset
, 0, &error
);
651 KASSERT(elm
->base
.btype
== node
->ondisk
->type
,
652 ("BTYPE MISMATCH %c %c NODE %p",
653 elm
->base
.btype
, node
->ondisk
->type
, node
));
654 if (node
->ondisk
->parent
!= cursor
->parent
->node_offset
)
655 hpanic("node %p %016jx vs %016jx",
657 (intmax_t)node
->ondisk
->parent
,
658 (intmax_t)cursor
->parent
->node_offset
);
659 KKASSERT(node
->ondisk
->parent
== cursor
->parent
->node_offset
);
663 * If no error occured we can lock the new child node. If the
664 * node is deadlock flagged wait up to hammer_tdmux_ticks (1 second)
665 * for the deadlock to clear. Otherwise a large number of concurrent
666 * readers can continuously stall the flusher.
668 * We specifically do this in the cursor_down() code in order to
669 * deal with frontend top-down searches smashing against bottom-up
670 * flusher-based mirror updates. These collisions typically occur
671 * above the inode in the B-Tree and are not covered by the
672 * ip->cursor_exclreq_count logic.
676 if (node
->cursor_exclreq_count
&&
677 cursor
->trans
->type
!= HAMMER_TRANS_FLS
) {
678 tsleep(&node
->cursor_exclreq_count
, 0,
679 "hstag2", hammer_tdmux_ticks
);
682 hammer_lock_sh(&node
->lock
);
683 KKASSERT ((node
->flags
& HAMMER_NODE_DELETED
) == 0);
690 /************************************************************************
691 * DEADLOCK RECOVERY *
692 ************************************************************************
694 * These are the new deadlock recovery functions. Currently they are only
695 * used for the mirror propagation and physical node removal cases but
696 * ultimately the intention is to use them for all deadlock recovery
699 * WARNING! The contents of the cursor may be modified while unlocked.
700 * passive modifications including adjusting the node, parent,
701 * indexes, and leaf pointer.
703 * An outright removal of the element the cursor was pointing at
704 * will cause the HAMMER_CURSOR_TRACKED_RIPOUT flag to be set,
705 * which chains to causing the HAMMER_CURSOR_RETEST to be set
706 * when the cursor is locked again.
709 hammer_unlock_cursor(hammer_cursor_t cursor
)
713 KKASSERT((cursor
->flags
& HAMMER_CURSOR_TRACKED
) == 0);
714 KKASSERT(cursor
->node
);
717 * Release the cursor's locks and track B-Tree operations on node.
718 * While being tracked our cursor can be modified by other threads
719 * and the node may be replaced.
721 if (cursor
->parent
) {
722 hammer_unlock(&cursor
->parent
->lock
);
723 hammer_rel_node(cursor
->parent
);
724 cursor
->parent
= NULL
;
727 cursor
->flags
|= HAMMER_CURSOR_TRACKED
;
728 TAILQ_INSERT_TAIL(&node
->cursor_list
, cursor
, deadlk_entry
);
729 hammer_unlock(&node
->lock
);
733 * Get the cursor heated up again. The cursor's node may have
734 * changed and we might have to locate the new parent.
736 * If the exact element we were on got deleted RIPOUT will be
737 * set and we must clear ATEDISK so an iteration does not skip
738 * the element after it.
741 hammer_lock_cursor(hammer_cursor_t cursor
)
746 KKASSERT(cursor
->flags
& HAMMER_CURSOR_TRACKED
);
753 hammer_ref_node(node
);
754 hammer_lock_sh(&node
->lock
);
755 if (cursor
->node
== node
) {
756 hammer_rel_node(node
);
759 hammer_unlock(&node
->lock
);
760 hammer_rel_node(node
);
764 * Untrack the cursor, clean up, and re-establish the parent node.
766 TAILQ_REMOVE(&node
->cursor_list
, cursor
, deadlk_entry
);
767 cursor
->flags
&= ~HAMMER_CURSOR_TRACKED
;
770 * If a ripout has occured iterations must re-test the (new)
771 * current element. Clearing ATEDISK prevents the element from
772 * being skipped and RETEST causes it to be re-tested.
774 if (cursor
->flags
& HAMMER_CURSOR_TRACKED_RIPOUT
) {
775 cursor
->flags
&= ~HAMMER_CURSOR_TRACKED_RIPOUT
;
776 cursor
->flags
&= ~HAMMER_CURSOR_ATEDISK
;
777 cursor
->flags
|= HAMMER_CURSOR_RETEST
;
779 error
= hammer_load_cursor_parent(cursor
, 0);
784 * Recover from a deadlocked cursor, tracking any node removals or
785 * replacements. If the cursor's current node is removed by another
786 * thread (via btree_remove()) the cursor will be seeked upwards.
788 * The caller is working a modifying operation and must be holding the
789 * sync lock (shared). We do not release the sync lock because this
790 * would break atomicy.
793 hammer_recover_cursor(hammer_cursor_t cursor
)
795 hammer_transaction_t trans __debugvar
;
801 hammer_unlock_cursor(cursor
);
806 trans
= cursor
->trans
;
807 KKASSERT(trans
->sync_lock_refs
> 0);
810 * Wait for the deadlock to clear.
812 * Maintain exclreq_count / wakeup as necessary to notify new
813 * entrants into ip. We continue to hold the fs_token so our
814 * EDEADLK retry loop should get its chance before another thread
817 if (cursor
->deadlk_node
) {
819 if (ip
&& trans
->type
== HAMMER_TRANS_FLS
)
820 ++ip
->cursor_exclreq_count
;
821 ++cursor
->deadlk_node
->cursor_exclreq_count
;
823 hammer_lock_ex_ident(&cursor
->deadlk_node
->lock
, "hmrdlk");
824 hammer_unlock(&cursor
->deadlk_node
->lock
);
826 if (--cursor
->deadlk_node
->cursor_exclreq_count
== 0)
827 wakeup(&cursor
->deadlk_node
->cursor_exclreq_count
);
828 if (ip
&& trans
->type
== HAMMER_TRANS_FLS
) {
829 if (--ip
->cursor_exclreq_count
== 0)
830 wakeup(&ip
->cursor_exclreq_count
);
833 hammer_rel_node(cursor
->deadlk_node
);
834 cursor
->deadlk_node
= NULL
;
836 if (cursor
->deadlk_rec
) {
837 hammer_wait_mem_record_ident(cursor
->deadlk_rec
, "hmmdlr");
838 hammer_rel_mem_record(cursor
->deadlk_rec
);
839 cursor
->deadlk_rec
= NULL
;
841 error
= hammer_lock_cursor(cursor
);
846 * Dup ocursor to ncursor. ncursor inherits ocursor's locks and ocursor
847 * is effectively unlocked and becomes tracked. If ocursor was not locked
848 * then ncursor also inherits the tracking.
850 * After the caller finishes working with ncursor it must be cleaned up
851 * with hammer_done_cursor(), and the caller must re-lock ocursor.
854 hammer_push_cursor(hammer_cursor_t ocursor
)
856 hammer_cursor_t ncursor
;
861 hmp
= ocursor
->trans
->hmp
;
862 ncursor
= kmalloc(sizeof(*ncursor
), hmp
->m_misc
, M_WAITOK
| M_ZERO
);
863 bcopy(ocursor
, ncursor
, sizeof(*ocursor
));
865 node
= ocursor
->node
;
866 hammer_ref_node(node
);
867 if ((ocursor
->flags
& HAMMER_CURSOR_TRACKED
) == 0) {
868 ocursor
->flags
|= HAMMER_CURSOR_TRACKED
;
869 TAILQ_INSERT_TAIL(&node
->cursor_list
, ocursor
, deadlk_entry
);
872 ocursor
->parent
= NULL
;
873 ocursor
->data_buffer
= NULL
;
874 ocursor
->leaf
= NULL
;
875 ocursor
->data
= NULL
;
876 if (ncursor
->flags
& HAMMER_CURSOR_TRACKED
)
877 TAILQ_INSERT_TAIL(&node
->cursor_list
, ncursor
, deadlk_entry
);
878 if ((ip
= ncursor
->ip
) != NULL
) {
879 ++ip
->cursor_ip_refs
;
882 hammer_ref(&ncursor
->iprec
->lock
);
887 * Destroy ncursor and restore ocursor
889 * This is a temporary hack for the release. We can't afford to lose
890 * the IP lock until the IP object scan code is able to deal with it,
891 * so have ocursor inherit it back.
894 hammer_pop_cursor(hammer_cursor_t ocursor
, hammer_cursor_t ncursor
)
899 hmp
= ncursor
->trans
->hmp
;
903 --ip
->cursor_ip_refs
;
904 hammer_done_cursor(ncursor
);
905 kfree(ncursor
, hmp
->m_misc
);
906 KKASSERT(ocursor
->ip
== ip
);
907 hammer_lock_cursor(ocursor
);
911 * onode is being replaced by nnode by the reblocking code.
914 hammer_cursor_replaced_node(hammer_node_t onode
, hammer_node_t nnode
)
916 hammer_cursor_t cursor
;
917 hammer_node_ondisk_t ondisk
;
918 hammer_node_ondisk_t nndisk
;
920 ondisk
= onode
->ondisk
;
921 nndisk
= nnode
->ondisk
;
923 while ((cursor
= TAILQ_FIRST(&onode
->cursor_list
)) != NULL
) {
924 TAILQ_REMOVE(&onode
->cursor_list
, cursor
, deadlk_entry
);
925 TAILQ_INSERT_TAIL(&nnode
->cursor_list
, cursor
, deadlk_entry
);
926 KKASSERT(cursor
->node
== onode
);
927 if (cursor
->leaf
== &ondisk
->elms
[cursor
->index
].leaf
)
928 cursor
->leaf
= &nndisk
->elms
[cursor
->index
].leaf
;
929 cursor
->node
= nnode
;
930 hammer_ref_node(nnode
);
931 hammer_rel_node(onode
);
936 * We have removed <node> from the parent and collapsed the parent.
938 * Cursors in deadlock recovery are seeked upward to the parent so the
939 * btree_remove() recursion works properly even though we have marked
940 * the cursor as requiring a reseek.
942 * This is the only cursor function which sets HAMMER_CURSOR_ITERATE_CHECK,
943 * meaning the cursor is no longer definitively pointing at an element
944 * within its iteration (if the cursor is being used to iterate). The
945 * iteration code will take this into account instead of asserting if the
946 * cursor is outside the iteration range.
949 hammer_cursor_removed_node(hammer_node_t node
, hammer_node_t parent
, int index
)
951 hammer_cursor_t cursor
;
952 hammer_node_ondisk_t ondisk
;
954 KKASSERT(parent
!= NULL
);
955 ondisk
= node
->ondisk
;
957 while ((cursor
= TAILQ_FIRST(&node
->cursor_list
)) != NULL
) {
958 KKASSERT(cursor
->node
== node
);
959 KKASSERT(cursor
->index
== 0);
960 TAILQ_REMOVE(&node
->cursor_list
, cursor
, deadlk_entry
);
961 TAILQ_INSERT_TAIL(&parent
->cursor_list
, cursor
, deadlk_entry
);
962 if (cursor
->leaf
== &ondisk
->elms
[cursor
->index
].leaf
)
964 cursor
->flags
|= HAMMER_CURSOR_TRACKED_RIPOUT
;
965 cursor
->flags
|= HAMMER_CURSOR_ITERATE_CHECK
;
966 cursor
->node
= parent
;
967 cursor
->index
= index
;
968 hammer_ref_node(parent
);
969 hammer_rel_node(node
);
974 * node was split at (onode, index) with elements >= index moved to nnode.
977 hammer_cursor_split_node(hammer_node_t onode
, hammer_node_t nnode
, int index
)
979 hammer_cursor_t cursor
;
980 hammer_node_ondisk_t ondisk
;
981 hammer_node_ondisk_t nndisk
;
983 ondisk
= onode
->ondisk
;
984 nndisk
= nnode
->ondisk
;
987 TAILQ_FOREACH(cursor
, &onode
->cursor_list
, deadlk_entry
) {
988 KKASSERT(cursor
->node
== onode
);
989 if (cursor
->index
< index
)
991 TAILQ_REMOVE(&onode
->cursor_list
, cursor
, deadlk_entry
);
992 TAILQ_INSERT_TAIL(&nnode
->cursor_list
, cursor
, deadlk_entry
);
993 if (cursor
->leaf
== &ondisk
->elms
[cursor
->index
].leaf
)
994 cursor
->leaf
= &nndisk
->elms
[cursor
->index
- index
].leaf
;
995 cursor
->node
= nnode
;
996 cursor
->index
-= index
;
997 hammer_ref_node(nnode
);
998 hammer_rel_node(onode
);
1004 * An element was moved from one node to another or within a node. The
1005 * index may also represent the end of the node (index == numelements).
1007 * {oparent,pindex} is the parent node's pointer to onode/oindex.
1009 * This is used by the rebalancing code. This is not an insertion or
1010 * deletion and any additional elements, including the degenerate case at
1011 * the end of the node, will be dealt with by additional distinct calls.
1014 hammer_cursor_moved_element(hammer_node_t oparent
, int pindex
,
1015 hammer_node_t onode
, int oindex
,
1016 hammer_node_t nnode
, int nindex
)
1018 hammer_cursor_t cursor
;
1019 hammer_node_ondisk_t ondisk
;
1020 hammer_node_ondisk_t nndisk
;
1023 * Adjust any cursors pointing at the element
1025 ondisk
= onode
->ondisk
;
1026 nndisk
= nnode
->ondisk
;
1028 TAILQ_FOREACH(cursor
, &onode
->cursor_list
, deadlk_entry
) {
1029 KKASSERT(cursor
->node
== onode
);
1030 if (cursor
->index
!= oindex
)
1032 TAILQ_REMOVE(&onode
->cursor_list
, cursor
, deadlk_entry
);
1033 TAILQ_INSERT_TAIL(&nnode
->cursor_list
, cursor
, deadlk_entry
);
1034 if (cursor
->leaf
== &ondisk
->elms
[oindex
].leaf
)
1035 cursor
->leaf
= &nndisk
->elms
[nindex
].leaf
;
1036 cursor
->node
= nnode
;
1037 cursor
->index
= nindex
;
1038 hammer_ref_node(nnode
);
1039 hammer_rel_node(onode
);
1044 * When moving the first element of onode to a different node any
1045 * cursor which is pointing at (oparent,pindex) must be repointed
1046 * to nnode and ATEDISK must be cleared.
1048 * This prevents cursors from losing track due to insertions.
1049 * Insertions temporarily release the cursor in order to update
1050 * the mirror_tids. It primarily effects the mirror_write code.
1051 * The other code paths generally only do a single insertion and
1052 * then relookup or drop the cursor.
1054 if (onode
== nnode
|| oindex
)
1056 ondisk
= oparent
->ondisk
;
1058 TAILQ_FOREACH(cursor
, &oparent
->cursor_list
, deadlk_entry
) {
1059 KKASSERT(cursor
->node
== oparent
);
1060 if (cursor
->index
!= pindex
)
1062 hkprintf("debug: shifted cursor pointing at parent\n"
1063 "parent %016jx:%d onode %016jx:%d nnode %016jx:%d\n",
1064 (intmax_t)oparent
->node_offset
, pindex
,
1065 (intmax_t)onode
->node_offset
, oindex
,
1066 (intmax_t)nnode
->node_offset
, nindex
);
1067 TAILQ_REMOVE(&oparent
->cursor_list
, cursor
, deadlk_entry
);
1068 TAILQ_INSERT_TAIL(&nnode
->cursor_list
, cursor
, deadlk_entry
);
1069 if (cursor
->leaf
== &ondisk
->elms
[oindex
].leaf
)
1070 cursor
->leaf
= &nndisk
->elms
[nindex
].leaf
;
1071 cursor
->node
= nnode
;
1072 cursor
->index
= nindex
;
1073 cursor
->flags
&= ~HAMMER_CURSOR_ATEDISK
;
1074 hammer_ref_node(nnode
);
1075 hammer_rel_node(oparent
);
1081 * The B-Tree element pointing to the specified node was moved from (oparent)
1082 * to (nparent, nindex). We must locate any tracked cursors pointing at
1083 * node and adjust their parent accordingly.
1085 * This is used by the rebalancing code when packing elements causes an
1086 * element to shift from one node to another.
1089 hammer_cursor_parent_changed(hammer_node_t node
, hammer_node_t oparent
,
1090 hammer_node_t nparent
, int nindex
)
1092 hammer_cursor_t cursor
;
1095 TAILQ_FOREACH(cursor
, &node
->cursor_list
, deadlk_entry
) {
1096 KKASSERT(cursor
->node
== node
);
1097 if (cursor
->parent
== oparent
) {
1098 cursor
->parent
= nparent
;
1099 cursor
->parent_index
= nindex
;
1100 hammer_ref_node(nparent
);
1101 hammer_rel_node(oparent
);
1108 * Deleted element at (node, index)
1110 * Shift indexes >= index
1113 hammer_cursor_deleted_element(hammer_node_t node
, int index
)
1115 hammer_cursor_t cursor
;
1116 hammer_node_ondisk_t ondisk
;
1118 ondisk
= node
->ondisk
;
1120 TAILQ_FOREACH(cursor
, &node
->cursor_list
, deadlk_entry
) {
1121 KKASSERT(cursor
->node
== node
);
1122 if (cursor
->index
== index
) {
1123 cursor
->flags
|= HAMMER_CURSOR_TRACKED_RIPOUT
;
1124 if (cursor
->leaf
== &ondisk
->elms
[cursor
->index
].leaf
)
1125 cursor
->leaf
= NULL
;
1126 } else if (cursor
->index
> index
) {
1127 if (cursor
->leaf
== &ondisk
->elms
[cursor
->index
].leaf
)
1128 cursor
->leaf
= &ondisk
->elms
[cursor
->index
- 1].leaf
;
1135 * Inserted element at (node, index)
1137 * Shift indexes >= index
1140 hammer_cursor_inserted_element(hammer_node_t node
, int index
)
1142 hammer_cursor_t cursor
;
1143 hammer_node_ondisk_t ondisk
;
1145 ondisk
= node
->ondisk
;
1147 TAILQ_FOREACH(cursor
, &node
->cursor_list
, deadlk_entry
) {
1148 KKASSERT(cursor
->node
== node
);
1149 if (cursor
->index
>= index
) {
1150 if (cursor
->leaf
== &ondisk
->elms
[cursor
->index
].leaf
)
1151 cursor
->leaf
= &ondisk
->elms
[cursor
->index
+ 1].leaf
;
1158 * Invalidate the cached data buffer associated with a cursor.
1160 * This needs to be done when the underlying block is being freed or
1161 * the referenced buffer can prevent the related buffer cache buffer
1162 * from being properly invalidated.
1165 hammer_cursor_invalidate_cache(hammer_cursor_t cursor
)
1167 if (cursor
->data_buffer
) {
1168 hammer_rel_buffer(cursor
->data_buffer
, 0);
1169 cursor
->data_buffer
= NULL
;
1170 cursor
->data
= NULL
;