2 * Copyright (C) 2009 Oracle. All rights reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
19 #include <linux/sched.h>
20 #include <linux/slab.h>
21 #include <linux/sort.h>
23 #include "delayed-ref.h"
24 #include "transaction.h"
27 * delayed back reference update tracking. For subvolume trees
28 * we queue up extent allocations and backref maintenance for
29 * delayed processing. This avoids deep call chains where we
30 * add extents in the middle of btrfs_search_slot, and it allows
31 * us to buffer up frequently modified backrefs in an rb tree instead
32 * of hammering updates on the extent allocation tree.
36 * compare two delayed tree backrefs with same bytenr and type
38 static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref2,
39 struct btrfs_delayed_tree_ref *ref1)
41 if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) {
42 if (ref1->root < ref2->root)
44 if (ref1->root > ref2->root)
47 if (ref1->parent < ref2->parent)
49 if (ref1->parent > ref2->parent)
56 * compare two delayed data backrefs with same bytenr and type
58 static int comp_data_refs(struct btrfs_delayed_data_ref *ref2,
59 struct btrfs_delayed_data_ref *ref1)
61 if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
62 if (ref1->root < ref2->root)
64 if (ref1->root > ref2->root)
66 if (ref1->objectid < ref2->objectid)
68 if (ref1->objectid > ref2->objectid)
70 if (ref1->offset < ref2->offset)
72 if (ref1->offset > ref2->offset)
75 if (ref1->parent < ref2->parent)
77 if (ref1->parent > ref2->parent)
84 * entries in the rb tree are ordered by the byte number of the extent,
85 * type of the delayed backrefs and content of delayed backrefs.
87 static int comp_entry(struct btrfs_delayed_ref_node *ref2,
88 struct btrfs_delayed_ref_node *ref1)
90 if (ref1->bytenr < ref2->bytenr)
92 if (ref1->bytenr > ref2->bytenr)
94 if (ref1->is_head && ref2->is_head)
100 if (ref1->type < ref2->type)
102 if (ref1->type > ref2->type)
104 if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
105 ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) {
106 return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2),
107 btrfs_delayed_node_to_tree_ref(ref1));
108 } else if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY ||
109 ref1->type == BTRFS_SHARED_DATA_REF_KEY) {
110 return comp_data_refs(btrfs_delayed_node_to_data_ref(ref2),
111 btrfs_delayed_node_to_data_ref(ref1));
118 * insert a new ref into the rbtree. This returns any existing refs
119 * for the same (bytenr,parent) tuple, or NULL if the new node was properly
122 static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root,
123 struct rb_node *node)
125 struct rb_node **p = &root->rb_node;
126 struct rb_node *parent_node = NULL;
127 struct btrfs_delayed_ref_node *entry;
128 struct btrfs_delayed_ref_node *ins;
131 ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
134 entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
137 cmp = comp_entry(entry, ins);
146 rb_link_node(node, parent_node, p);
147 rb_insert_color(node, root);
152 * find an head entry based on bytenr. This returns the delayed ref
153 * head if it was able to find one, or NULL if nothing was in that spot
155 static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root,
157 struct btrfs_delayed_ref_node **last)
159 struct rb_node *n = root->rb_node;
160 struct btrfs_delayed_ref_node *entry;
164 entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
165 WARN_ON(!entry->in_tree);
169 if (bytenr < entry->bytenr)
171 else if (bytenr > entry->bytenr)
173 else if (!btrfs_delayed_ref_is_head(entry))
188 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
189 struct btrfs_delayed_ref_head *head)
191 struct btrfs_delayed_ref_root *delayed_refs;
193 delayed_refs = &trans->transaction->delayed_refs;
194 assert_spin_locked(&delayed_refs->lock);
195 if (mutex_trylock(&head->mutex))
198 atomic_inc(&head->node.refs);
199 spin_unlock(&delayed_refs->lock);
201 mutex_lock(&head->mutex);
202 spin_lock(&delayed_refs->lock);
203 if (!head->node.in_tree) {
204 mutex_unlock(&head->mutex);
205 btrfs_put_delayed_ref(&head->node);
208 btrfs_put_delayed_ref(&head->node);
212 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
213 struct list_head *cluster, u64 start)
216 struct btrfs_delayed_ref_root *delayed_refs;
217 struct rb_node *node;
218 struct btrfs_delayed_ref_node *ref;
219 struct btrfs_delayed_ref_head *head;
221 delayed_refs = &trans->transaction->delayed_refs;
223 node = rb_first(&delayed_refs->root);
226 find_ref_head(&delayed_refs->root, start, &ref);
228 struct btrfs_delayed_ref_node *tmp;
230 node = rb_prev(&ref->rb_node);
233 struct btrfs_delayed_ref_node,
235 if (tmp->bytenr < start)
238 node = rb_prev(&ref->rb_node);
240 node = &ref->rb_node;
242 node = rb_first(&delayed_refs->root);
245 while (node && count < 32) {
246 ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
247 if (btrfs_delayed_ref_is_head(ref)) {
248 head = btrfs_delayed_node_to_head(ref);
249 if (list_empty(&head->cluster)) {
250 list_add_tail(&head->cluster, cluster);
251 delayed_refs->run_delayed_start =
255 WARN_ON(delayed_refs->num_heads_ready == 0);
256 delayed_refs->num_heads_ready--;
258 /* the goal of the clustering is to find extents
259 * that are likely to end up in the same extent
260 * leaf on disk. So, we don't want them spread
261 * all over the tree. Stop now if we've hit
262 * a head that was already in use
267 node = rb_next(node);
273 * we've gone to the end of the rbtree without finding any
274 * clusters. start from the beginning and try again
277 node = rb_first(&delayed_refs->root);
284 * helper function to update an extent delayed ref in the
285 * rbtree. existing and update must both have the same
288 * This may free existing if the update cancels out whatever
289 * operation it was doing.
292 update_existing_ref(struct btrfs_trans_handle *trans,
293 struct btrfs_delayed_ref_root *delayed_refs,
294 struct btrfs_delayed_ref_node *existing,
295 struct btrfs_delayed_ref_node *update)
297 if (update->action != existing->action) {
299 * this is effectively undoing either an add or a
300 * drop. We decrement the ref_mod, and if it goes
301 * down to zero we just delete the entry without
302 * every changing the extent allocation tree.
305 if (existing->ref_mod == 0) {
306 rb_erase(&existing->rb_node,
307 &delayed_refs->root);
308 existing->in_tree = 0;
309 btrfs_put_delayed_ref(existing);
310 delayed_refs->num_entries--;
311 if (trans->delayed_ref_updates)
312 trans->delayed_ref_updates--;
314 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
315 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
318 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
319 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
321 * the action on the existing ref matches
322 * the action on the ref we're trying to add.
323 * Bump the ref_mod by one so the backref that
324 * is eventually added/removed has the correct
327 existing->ref_mod += update->ref_mod;
332 * helper function to update the accounting in the head ref
333 * existing and update must have the same bytenr
336 update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
337 struct btrfs_delayed_ref_node *update)
339 struct btrfs_delayed_ref_head *existing_ref;
340 struct btrfs_delayed_ref_head *ref;
342 existing_ref = btrfs_delayed_node_to_head(existing);
343 ref = btrfs_delayed_node_to_head(update);
344 BUG_ON(existing_ref->is_data != ref->is_data);
346 if (ref->must_insert_reserved) {
347 /* if the extent was freed and then
348 * reallocated before the delayed ref
349 * entries were processed, we can end up
350 * with an existing head ref without
351 * the must_insert_reserved flag set.
354 existing_ref->must_insert_reserved = ref->must_insert_reserved;
357 * update the num_bytes so we make sure the accounting
360 existing->num_bytes = update->num_bytes;
364 if (ref->extent_op) {
365 if (!existing_ref->extent_op) {
366 existing_ref->extent_op = ref->extent_op;
368 if (ref->extent_op->update_key) {
369 memcpy(&existing_ref->extent_op->key,
370 &ref->extent_op->key,
371 sizeof(ref->extent_op->key));
372 existing_ref->extent_op->update_key = 1;
374 if (ref->extent_op->update_flags) {
375 existing_ref->extent_op->flags_to_set |=
376 ref->extent_op->flags_to_set;
377 existing_ref->extent_op->update_flags = 1;
379 kfree(ref->extent_op);
383 * update the reference mod on the head to reflect this new operation
385 existing->ref_mod += update->ref_mod;
389 * helper function to actually insert a head node into the rbtree.
390 * this does all the dirty work in terms of maintaining the correct
391 * overall modification count.
393 static noinline int add_delayed_ref_head(struct btrfs_fs_info *fs_info,
394 struct btrfs_trans_handle *trans,
395 struct btrfs_delayed_ref_node *ref,
396 u64 bytenr, u64 num_bytes,
397 int action, int is_data)
399 struct btrfs_delayed_ref_node *existing;
400 struct btrfs_delayed_ref_head *head_ref = NULL;
401 struct btrfs_delayed_ref_root *delayed_refs;
403 int must_insert_reserved = 0;
406 * the head node stores the sum of all the mods, so dropping a ref
407 * should drop the sum in the head node by one.
409 if (action == BTRFS_UPDATE_DELAYED_HEAD)
411 else if (action == BTRFS_DROP_DELAYED_REF)
415 * BTRFS_ADD_DELAYED_EXTENT means that we need to update
416 * the reserved accounting when the extent is finally added, or
417 * if a later modification deletes the delayed ref without ever
418 * inserting the extent into the extent allocation tree.
419 * ref->must_insert_reserved is the flag used to record
420 * that accounting mods are required.
422 * Once we record must_insert_reserved, switch the action to
423 * BTRFS_ADD_DELAYED_REF because other special casing is not required.
425 if (action == BTRFS_ADD_DELAYED_EXTENT)
426 must_insert_reserved = 1;
428 must_insert_reserved = 0;
430 delayed_refs = &trans->transaction->delayed_refs;
432 /* first set the basic ref node struct up */
433 atomic_set(&ref->refs, 1);
434 ref->bytenr = bytenr;
435 ref->num_bytes = num_bytes;
436 ref->ref_mod = count_mod;
442 head_ref = btrfs_delayed_node_to_head(ref);
443 head_ref->must_insert_reserved = must_insert_reserved;
444 head_ref->is_data = is_data;
446 INIT_LIST_HEAD(&head_ref->cluster);
447 mutex_init(&head_ref->mutex);
449 trace_btrfs_delayed_ref_head(ref, head_ref, action);
451 existing = tree_insert(&delayed_refs->root, &ref->rb_node);
454 update_existing_head_ref(existing, ref);
456 * we've updated the existing ref, free the newly
461 delayed_refs->num_heads++;
462 delayed_refs->num_heads_ready++;
463 delayed_refs->num_entries++;
464 trans->delayed_ref_updates++;
470 * helper to insert a delayed tree ref into the rbtree.
472 static noinline int add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
473 struct btrfs_trans_handle *trans,
474 struct btrfs_delayed_ref_node *ref,
475 u64 bytenr, u64 num_bytes, u64 parent,
476 u64 ref_root, int level, int action,
479 struct btrfs_delayed_ref_node *existing;
480 struct btrfs_delayed_tree_ref *full_ref;
481 struct btrfs_delayed_ref_root *delayed_refs;
483 if (action == BTRFS_ADD_DELAYED_EXTENT)
484 action = BTRFS_ADD_DELAYED_REF;
486 delayed_refs = &trans->transaction->delayed_refs;
488 /* first set the basic ref node struct up */
489 atomic_set(&ref->refs, 1);
490 ref->bytenr = bytenr;
491 ref->num_bytes = num_bytes;
493 ref->action = action;
497 full_ref = btrfs_delayed_node_to_tree_ref(ref);
498 full_ref->parent = parent;
499 full_ref->root = ref_root;
501 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
503 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
504 full_ref->level = level;
506 trace_btrfs_delayed_tree_ref(ref, full_ref, action);
508 existing = tree_insert(&delayed_refs->root, &ref->rb_node);
511 update_existing_ref(trans, delayed_refs, existing, ref);
513 * we've updated the existing ref, free the newly
518 delayed_refs->num_entries++;
519 trans->delayed_ref_updates++;
525 * helper to insert a delayed data ref into the rbtree.
527 static noinline int add_delayed_data_ref(struct btrfs_fs_info *fs_info,
528 struct btrfs_trans_handle *trans,
529 struct btrfs_delayed_ref_node *ref,
530 u64 bytenr, u64 num_bytes, u64 parent,
531 u64 ref_root, u64 owner, u64 offset,
532 int action, int for_cow)
534 struct btrfs_delayed_ref_node *existing;
535 struct btrfs_delayed_data_ref *full_ref;
536 struct btrfs_delayed_ref_root *delayed_refs;
538 if (action == BTRFS_ADD_DELAYED_EXTENT)
539 action = BTRFS_ADD_DELAYED_REF;
541 delayed_refs = &trans->transaction->delayed_refs;
543 /* first set the basic ref node struct up */
544 atomic_set(&ref->refs, 1);
545 ref->bytenr = bytenr;
546 ref->num_bytes = num_bytes;
548 ref->action = action;
552 full_ref = btrfs_delayed_node_to_data_ref(ref);
553 full_ref->parent = parent;
554 full_ref->root = ref_root;
556 ref->type = BTRFS_SHARED_DATA_REF_KEY;
558 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
560 full_ref->objectid = owner;
561 full_ref->offset = offset;
563 trace_btrfs_delayed_data_ref(ref, full_ref, action);
565 existing = tree_insert(&delayed_refs->root, &ref->rb_node);
568 update_existing_ref(trans, delayed_refs, existing, ref);
570 * we've updated the existing ref, free the newly
575 delayed_refs->num_entries++;
576 trans->delayed_ref_updates++;
582 * add a delayed tree ref. This does all of the accounting required
583 * to make sure the delayed ref is eventually processed before this
584 * transaction commits.
586 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
587 struct btrfs_trans_handle *trans,
588 u64 bytenr, u64 num_bytes, u64 parent,
589 u64 ref_root, int level, int action,
590 struct btrfs_delayed_extent_op *extent_op,
593 struct btrfs_delayed_tree_ref *ref;
594 struct btrfs_delayed_ref_head *head_ref;
595 struct btrfs_delayed_ref_root *delayed_refs;
598 BUG_ON(extent_op && extent_op->is_data);
599 ref = kmalloc(sizeof(*ref), GFP_NOFS);
603 head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
609 head_ref->extent_op = extent_op;
611 delayed_refs = &trans->transaction->delayed_refs;
612 spin_lock(&delayed_refs->lock);
615 * insert both the head node and the new ref without dropping
618 ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
619 num_bytes, action, 0);
622 ret = add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
623 num_bytes, parent, ref_root, level, action,
626 spin_unlock(&delayed_refs->lock);
631 * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
633 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
634 struct btrfs_trans_handle *trans,
635 u64 bytenr, u64 num_bytes,
636 u64 parent, u64 ref_root,
637 u64 owner, u64 offset, int action,
638 struct btrfs_delayed_extent_op *extent_op,
641 struct btrfs_delayed_data_ref *ref;
642 struct btrfs_delayed_ref_head *head_ref;
643 struct btrfs_delayed_ref_root *delayed_refs;
646 BUG_ON(extent_op && !extent_op->is_data);
647 ref = kmalloc(sizeof(*ref), GFP_NOFS);
651 head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
657 head_ref->extent_op = extent_op;
659 delayed_refs = &trans->transaction->delayed_refs;
660 spin_lock(&delayed_refs->lock);
663 * insert both the head node and the new ref without dropping
666 ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
667 num_bytes, action, 1);
670 ret = add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
671 num_bytes, parent, ref_root, owner, offset,
674 spin_unlock(&delayed_refs->lock);
678 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
679 struct btrfs_trans_handle *trans,
680 u64 bytenr, u64 num_bytes,
681 struct btrfs_delayed_extent_op *extent_op)
683 struct btrfs_delayed_ref_head *head_ref;
684 struct btrfs_delayed_ref_root *delayed_refs;
687 head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
691 head_ref->extent_op = extent_op;
693 delayed_refs = &trans->transaction->delayed_refs;
694 spin_lock(&delayed_refs->lock);
696 ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
697 num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
701 spin_unlock(&delayed_refs->lock);
706 * this does a simple search for the head node for a given extent.
707 * It must be called with the delayed ref spinlock held, and it returns
708 * the head node if any where found, or NULL if not.
710 struct btrfs_delayed_ref_head *
711 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
713 struct btrfs_delayed_ref_node *ref;
714 struct btrfs_delayed_ref_root *delayed_refs;
716 delayed_refs = &trans->transaction->delayed_refs;
717 ref = find_ref_head(&delayed_refs->root, bytenr, NULL);
719 return btrfs_delayed_node_to_head(ref);