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v3.5.6
  1/*
  2 * Copyright (C) 2009 Oracle.  All rights reserved.
  3 *
  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.
  7 *
  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.
 12 *
 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.
 17 */
 18
 19#include <linux/sched.h>
 20#include <linux/slab.h>
 21#include <linux/sort.h>
 22#include "ctree.h"
 23#include "delayed-ref.h"
 24#include "transaction.h"
 25
 26/*
 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.
 33 */
 34
 35/*
 36 * compare two delayed tree backrefs with same bytenr and type
 37 */
 38static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref2,
 39			  struct btrfs_delayed_tree_ref *ref1)
 40{
 41	if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) {
 42		if (ref1->root < ref2->root)
 43			return -1;
 44		if (ref1->root > ref2->root)
 45			return 1;
 46	} else {
 47		if (ref1->parent < ref2->parent)
 48			return -1;
 49		if (ref1->parent > ref2->parent)
 50			return 1;
 51	}
 52	return 0;
 53}
 54
 55/*
 56 * compare two delayed data backrefs with same bytenr and type
 57 */
 58static int comp_data_refs(struct btrfs_delayed_data_ref *ref2,
 59			  struct btrfs_delayed_data_ref *ref1)
 60{
 61	if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
 62		if (ref1->root < ref2->root)
 63			return -1;
 64		if (ref1->root > ref2->root)
 65			return 1;
 66		if (ref1->objectid < ref2->objectid)
 67			return -1;
 68		if (ref1->objectid > ref2->objectid)
 69			return 1;
 70		if (ref1->offset < ref2->offset)
 71			return -1;
 72		if (ref1->offset > ref2->offset)
 73			return 1;
 74	} else {
 75		if (ref1->parent < ref2->parent)
 76			return -1;
 77		if (ref1->parent > ref2->parent)
 78			return 1;
 79	}
 80	return 0;
 81}
 82
 83/*
 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.
 86 */
 87static int comp_entry(struct btrfs_delayed_ref_node *ref2,
 88		      struct btrfs_delayed_ref_node *ref1)
 89{
 90	if (ref1->bytenr < ref2->bytenr)
 91		return -1;
 92	if (ref1->bytenr > ref2->bytenr)
 93		return 1;
 94	if (ref1->is_head && ref2->is_head)
 95		return 0;
 96	if (ref2->is_head)
 97		return -1;
 98	if (ref1->is_head)
 99		return 1;
100	if (ref1->type < ref2->type)
101		return -1;
102	if (ref1->type > ref2->type)
103		return 1;
104	/* merging of sequenced refs is not allowed */
105	if (ref1->seq < ref2->seq)
106		return -1;
107	if (ref1->seq > ref2->seq)
108		return 1;
109	if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
110	    ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) {
111		return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2),
112				      btrfs_delayed_node_to_tree_ref(ref1));
113	} else if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY ||
114		   ref1->type == BTRFS_SHARED_DATA_REF_KEY) {
115		return comp_data_refs(btrfs_delayed_node_to_data_ref(ref2),
116				      btrfs_delayed_node_to_data_ref(ref1));
117	}
118	BUG();
119	return 0;
120}
121
122/*
123 * insert a new ref into the rbtree.  This returns any existing refs
124 * for the same (bytenr,parent) tuple, or NULL if the new node was properly
125 * inserted.
126 */
127static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root,
128						  struct rb_node *node)
129{
130	struct rb_node **p = &root->rb_node;
131	struct rb_node *parent_node = NULL;
132	struct btrfs_delayed_ref_node *entry;
133	struct btrfs_delayed_ref_node *ins;
134	int cmp;
135
136	ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
137	while (*p) {
138		parent_node = *p;
139		entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
140				 rb_node);
141
142		cmp = comp_entry(entry, ins);
143		if (cmp < 0)
144			p = &(*p)->rb_left;
145		else if (cmp > 0)
146			p = &(*p)->rb_right;
147		else
148			return entry;
149	}
150
151	rb_link_node(node, parent_node, p);
152	rb_insert_color(node, root);
153	return NULL;
154}
155
156/*
157 * find an head entry based on bytenr. This returns the delayed ref
158 * head if it was able to find one, or NULL if nothing was in that spot.
159 * If return_bigger is given, the next bigger entry is returned if no exact
160 * match is found.
161 */
162static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root,
163				  u64 bytenr,
164				  struct btrfs_delayed_ref_node **last,
165				  int return_bigger)
166{
167	struct rb_node *n;
168	struct btrfs_delayed_ref_node *entry;
169	int cmp = 0;
170
171again:
172	n = root->rb_node;
173	entry = NULL;
174	while (n) {
175		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
176		WARN_ON(!entry->in_tree);
177		if (last)
178			*last = entry;
179
180		if (bytenr < entry->bytenr)
181			cmp = -1;
182		else if (bytenr > entry->bytenr)
183			cmp = 1;
184		else if (!btrfs_delayed_ref_is_head(entry))
185			cmp = 1;
186		else
187			cmp = 0;
188
189		if (cmp < 0)
190			n = n->rb_left;
191		else if (cmp > 0)
192			n = n->rb_right;
193		else
194			return entry;
195	}
196	if (entry && return_bigger) {
197		if (cmp > 0) {
198			n = rb_next(&entry->rb_node);
199			if (!n)
200				n = rb_first(root);
201			entry = rb_entry(n, struct btrfs_delayed_ref_node,
202					 rb_node);
203			bytenr = entry->bytenr;
204			return_bigger = 0;
205			goto again;
206		}
207		return entry;
208	}
209	return NULL;
210}
211
212int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
213			   struct btrfs_delayed_ref_head *head)
214{
215	struct btrfs_delayed_ref_root *delayed_refs;
216
217	delayed_refs = &trans->transaction->delayed_refs;
218	assert_spin_locked(&delayed_refs->lock);
219	if (mutex_trylock(&head->mutex))
220		return 0;
221
222	atomic_inc(&head->node.refs);
223	spin_unlock(&delayed_refs->lock);
224
225	mutex_lock(&head->mutex);
226	spin_lock(&delayed_refs->lock);
227	if (!head->node.in_tree) {
228		mutex_unlock(&head->mutex);
229		btrfs_put_delayed_ref(&head->node);
230		return -EAGAIN;
231	}
232	btrfs_put_delayed_ref(&head->node);
233	return 0;
234}
235
236int btrfs_check_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs,
237			    u64 seq)
238{
239	struct seq_list *elem;
240
241	assert_spin_locked(&delayed_refs->lock);
242	if (list_empty(&delayed_refs->seq_head))
243		return 0;
244
245	elem = list_first_entry(&delayed_refs->seq_head, struct seq_list, list);
246	if (seq >= elem->seq) {
247		pr_debug("holding back delayed_ref %llu, lowest is %llu (%p)\n",
248			 seq, elem->seq, delayed_refs);
249		return 1;
250	}
251	return 0;
252}
253
254int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
255			   struct list_head *cluster, u64 start)
256{
257	int count = 0;
258	struct btrfs_delayed_ref_root *delayed_refs;
259	struct rb_node *node;
260	struct btrfs_delayed_ref_node *ref;
261	struct btrfs_delayed_ref_head *head;
262
263	delayed_refs = &trans->transaction->delayed_refs;
264	if (start == 0) {
265		node = rb_first(&delayed_refs->root);
266	} else {
267		ref = NULL;
268		find_ref_head(&delayed_refs->root, start + 1, &ref, 1);
269		if (ref) {
 
 
 
 
 
 
 
 
 
 
 
 
270			node = &ref->rb_node;
271		} else
272			node = rb_first(&delayed_refs->root);
273	}
274again:
275	while (node && count < 32) {
276		ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
277		if (btrfs_delayed_ref_is_head(ref)) {
278			head = btrfs_delayed_node_to_head(ref);
279			if (list_empty(&head->cluster)) {
280				list_add_tail(&head->cluster, cluster);
281				delayed_refs->run_delayed_start =
282					head->node.bytenr;
283				count++;
284
285				WARN_ON(delayed_refs->num_heads_ready == 0);
286				delayed_refs->num_heads_ready--;
287			} else if (count) {
288				/* the goal of the clustering is to find extents
289				 * that are likely to end up in the same extent
290				 * leaf on disk.  So, we don't want them spread
291				 * all over the tree.  Stop now if we've hit
292				 * a head that was already in use
293				 */
294				break;
295			}
296		}
297		node = rb_next(node);
298	}
299	if (count) {
300		return 0;
301	} else if (start) {
302		/*
303		 * we've gone to the end of the rbtree without finding any
304		 * clusters.  start from the beginning and try again
305		 */
306		start = 0;
307		node = rb_first(&delayed_refs->root);
308		goto again;
309	}
310	return 1;
311}
312
313/*
314 * helper function to update an extent delayed ref in the
315 * rbtree.  existing and update must both have the same
316 * bytenr and parent
317 *
318 * This may free existing if the update cancels out whatever
319 * operation it was doing.
320 */
321static noinline void
322update_existing_ref(struct btrfs_trans_handle *trans,
323		    struct btrfs_delayed_ref_root *delayed_refs,
324		    struct btrfs_delayed_ref_node *existing,
325		    struct btrfs_delayed_ref_node *update)
326{
327	if (update->action != existing->action) {
328		/*
329		 * this is effectively undoing either an add or a
330		 * drop.  We decrement the ref_mod, and if it goes
331		 * down to zero we just delete the entry without
332		 * every changing the extent allocation tree.
333		 */
334		existing->ref_mod--;
335		if (existing->ref_mod == 0) {
336			rb_erase(&existing->rb_node,
337				 &delayed_refs->root);
338			existing->in_tree = 0;
339			btrfs_put_delayed_ref(existing);
340			delayed_refs->num_entries--;
341			if (trans->delayed_ref_updates)
342				trans->delayed_ref_updates--;
343		} else {
344			WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
345				existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
346		}
347	} else {
348		WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
349			existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
350		/*
351		 * the action on the existing ref matches
352		 * the action on the ref we're trying to add.
353		 * Bump the ref_mod by one so the backref that
354		 * is eventually added/removed has the correct
355		 * reference count
356		 */
357		existing->ref_mod += update->ref_mod;
358	}
359}
360
361/*
362 * helper function to update the accounting in the head ref
363 * existing and update must have the same bytenr
364 */
365static noinline void
366update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
367			 struct btrfs_delayed_ref_node *update)
368{
369	struct btrfs_delayed_ref_head *existing_ref;
370	struct btrfs_delayed_ref_head *ref;
371
372	existing_ref = btrfs_delayed_node_to_head(existing);
373	ref = btrfs_delayed_node_to_head(update);
374	BUG_ON(existing_ref->is_data != ref->is_data);
375
376	if (ref->must_insert_reserved) {
377		/* if the extent was freed and then
378		 * reallocated before the delayed ref
379		 * entries were processed, we can end up
380		 * with an existing head ref without
381		 * the must_insert_reserved flag set.
382		 * Set it again here
383		 */
384		existing_ref->must_insert_reserved = ref->must_insert_reserved;
385
386		/*
387		 * update the num_bytes so we make sure the accounting
388		 * is done correctly
389		 */
390		existing->num_bytes = update->num_bytes;
391
392	}
393
394	if (ref->extent_op) {
395		if (!existing_ref->extent_op) {
396			existing_ref->extent_op = ref->extent_op;
397		} else {
398			if (ref->extent_op->update_key) {
399				memcpy(&existing_ref->extent_op->key,
400				       &ref->extent_op->key,
401				       sizeof(ref->extent_op->key));
402				existing_ref->extent_op->update_key = 1;
403			}
404			if (ref->extent_op->update_flags) {
405				existing_ref->extent_op->flags_to_set |=
406					ref->extent_op->flags_to_set;
407				existing_ref->extent_op->update_flags = 1;
408			}
409			kfree(ref->extent_op);
410		}
411	}
412	/*
413	 * update the reference mod on the head to reflect this new operation
414	 */
415	existing->ref_mod += update->ref_mod;
416}
417
418/*
419 * helper function to actually insert a head node into the rbtree.
420 * this does all the dirty work in terms of maintaining the correct
421 * overall modification count.
422 */
423static noinline void add_delayed_ref_head(struct btrfs_fs_info *fs_info,
424					struct btrfs_trans_handle *trans,
425					struct btrfs_delayed_ref_node *ref,
426					u64 bytenr, u64 num_bytes,
427					int action, int is_data)
428{
429	struct btrfs_delayed_ref_node *existing;
430	struct btrfs_delayed_ref_head *head_ref = NULL;
431	struct btrfs_delayed_ref_root *delayed_refs;
432	int count_mod = 1;
433	int must_insert_reserved = 0;
434
435	/*
436	 * the head node stores the sum of all the mods, so dropping a ref
437	 * should drop the sum in the head node by one.
438	 */
439	if (action == BTRFS_UPDATE_DELAYED_HEAD)
440		count_mod = 0;
441	else if (action == BTRFS_DROP_DELAYED_REF)
442		count_mod = -1;
443
444	/*
445	 * BTRFS_ADD_DELAYED_EXTENT means that we need to update
446	 * the reserved accounting when the extent is finally added, or
447	 * if a later modification deletes the delayed ref without ever
448	 * inserting the extent into the extent allocation tree.
449	 * ref->must_insert_reserved is the flag used to record
450	 * that accounting mods are required.
451	 *
452	 * Once we record must_insert_reserved, switch the action to
453	 * BTRFS_ADD_DELAYED_REF because other special casing is not required.
454	 */
455	if (action == BTRFS_ADD_DELAYED_EXTENT)
456		must_insert_reserved = 1;
457	else
458		must_insert_reserved = 0;
459
460	delayed_refs = &trans->transaction->delayed_refs;
461
462	/* first set the basic ref node struct up */
463	atomic_set(&ref->refs, 1);
464	ref->bytenr = bytenr;
465	ref->num_bytes = num_bytes;
466	ref->ref_mod = count_mod;
467	ref->type  = 0;
468	ref->action  = 0;
469	ref->is_head = 1;
470	ref->in_tree = 1;
471	ref->seq = 0;
472
473	head_ref = btrfs_delayed_node_to_head(ref);
474	head_ref->must_insert_reserved = must_insert_reserved;
475	head_ref->is_data = is_data;
476
477	INIT_LIST_HEAD(&head_ref->cluster);
478	mutex_init(&head_ref->mutex);
479
480	trace_btrfs_delayed_ref_head(ref, head_ref, action);
481
482	existing = tree_insert(&delayed_refs->root, &ref->rb_node);
483
484	if (existing) {
485		update_existing_head_ref(existing, ref);
486		/*
487		 * we've updated the existing ref, free the newly
488		 * allocated ref
489		 */
490		kfree(head_ref);
491	} else {
492		delayed_refs->num_heads++;
493		delayed_refs->num_heads_ready++;
494		delayed_refs->num_entries++;
495		trans->delayed_ref_updates++;
496	}
 
497}
498
499/*
500 * helper to insert a delayed tree ref into the rbtree.
501 */
502static noinline void add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
503					 struct btrfs_trans_handle *trans,
504					 struct btrfs_delayed_ref_node *ref,
505					 u64 bytenr, u64 num_bytes, u64 parent,
506					 u64 ref_root, int level, int action,
507					 int for_cow)
508{
509	struct btrfs_delayed_ref_node *existing;
510	struct btrfs_delayed_tree_ref *full_ref;
511	struct btrfs_delayed_ref_root *delayed_refs;
512	u64 seq = 0;
513
514	if (action == BTRFS_ADD_DELAYED_EXTENT)
515		action = BTRFS_ADD_DELAYED_REF;
516
517	delayed_refs = &trans->transaction->delayed_refs;
518
519	/* first set the basic ref node struct up */
520	atomic_set(&ref->refs, 1);
521	ref->bytenr = bytenr;
522	ref->num_bytes = num_bytes;
523	ref->ref_mod = 1;
524	ref->action = action;
525	ref->is_head = 0;
526	ref->in_tree = 1;
527
528	if (is_fstree(ref_root))
529		seq = inc_delayed_seq(delayed_refs);
530	ref->seq = seq;
531
532	full_ref = btrfs_delayed_node_to_tree_ref(ref);
533	full_ref->parent = parent;
534	full_ref->root = ref_root;
535	if (parent)
536		ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
537	else
 
538		ref->type = BTRFS_TREE_BLOCK_REF_KEY;
 
539	full_ref->level = level;
540
541	trace_btrfs_delayed_tree_ref(ref, full_ref, action);
542
543	existing = tree_insert(&delayed_refs->root, &ref->rb_node);
544
545	if (existing) {
546		update_existing_ref(trans, delayed_refs, existing, ref);
547		/*
548		 * we've updated the existing ref, free the newly
549		 * allocated ref
550		 */
551		kfree(full_ref);
552	} else {
553		delayed_refs->num_entries++;
554		trans->delayed_ref_updates++;
555	}
 
556}
557
558/*
559 * helper to insert a delayed data ref into the rbtree.
560 */
561static noinline void add_delayed_data_ref(struct btrfs_fs_info *fs_info,
562					 struct btrfs_trans_handle *trans,
563					 struct btrfs_delayed_ref_node *ref,
564					 u64 bytenr, u64 num_bytes, u64 parent,
565					 u64 ref_root, u64 owner, u64 offset,
566					 int action, int for_cow)
567{
568	struct btrfs_delayed_ref_node *existing;
569	struct btrfs_delayed_data_ref *full_ref;
570	struct btrfs_delayed_ref_root *delayed_refs;
571	u64 seq = 0;
572
573	if (action == BTRFS_ADD_DELAYED_EXTENT)
574		action = BTRFS_ADD_DELAYED_REF;
575
576	delayed_refs = &trans->transaction->delayed_refs;
577
578	/* first set the basic ref node struct up */
579	atomic_set(&ref->refs, 1);
580	ref->bytenr = bytenr;
581	ref->num_bytes = num_bytes;
582	ref->ref_mod = 1;
583	ref->action = action;
584	ref->is_head = 0;
585	ref->in_tree = 1;
586
587	if (is_fstree(ref_root))
588		seq = inc_delayed_seq(delayed_refs);
589	ref->seq = seq;
590
591	full_ref = btrfs_delayed_node_to_data_ref(ref);
592	full_ref->parent = parent;
593	full_ref->root = ref_root;
594	if (parent)
595		ref->type = BTRFS_SHARED_DATA_REF_KEY;
596	else
 
597		ref->type = BTRFS_EXTENT_DATA_REF_KEY;
598
599	full_ref->objectid = owner;
600	full_ref->offset = offset;
601
602	trace_btrfs_delayed_data_ref(ref, full_ref, action);
603
604	existing = tree_insert(&delayed_refs->root, &ref->rb_node);
605
606	if (existing) {
607		update_existing_ref(trans, delayed_refs, existing, ref);
608		/*
609		 * we've updated the existing ref, free the newly
610		 * allocated ref
611		 */
612		kfree(full_ref);
613	} else {
614		delayed_refs->num_entries++;
615		trans->delayed_ref_updates++;
616	}
 
617}
618
619/*
620 * add a delayed tree ref.  This does all of the accounting required
621 * to make sure the delayed ref is eventually processed before this
622 * transaction commits.
623 */
624int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
625			       struct btrfs_trans_handle *trans,
626			       u64 bytenr, u64 num_bytes, u64 parent,
627			       u64 ref_root,  int level, int action,
628			       struct btrfs_delayed_extent_op *extent_op,
629			       int for_cow)
630{
631	struct btrfs_delayed_tree_ref *ref;
632	struct btrfs_delayed_ref_head *head_ref;
633	struct btrfs_delayed_ref_root *delayed_refs;
 
634
635	BUG_ON(extent_op && extent_op->is_data);
636	ref = kmalloc(sizeof(*ref), GFP_NOFS);
637	if (!ref)
638		return -ENOMEM;
639
640	head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
641	if (!head_ref) {
642		kfree(ref);
643		return -ENOMEM;
644	}
645
646	head_ref->extent_op = extent_op;
647
648	delayed_refs = &trans->transaction->delayed_refs;
649	spin_lock(&delayed_refs->lock);
650
651	/*
652	 * insert both the head node and the new ref without dropping
653	 * the spin lock
654	 */
655	add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
656				   num_bytes, action, 0);
657
658	add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
659				   num_bytes, parent, ref_root, level, action,
660				   for_cow);
661	if (!is_fstree(ref_root) &&
662	    waitqueue_active(&delayed_refs->seq_wait))
663		wake_up(&delayed_refs->seq_wait);
664	spin_unlock(&delayed_refs->lock);
665
666	return 0;
667}
668
669/*
670 * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
671 */
672int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
673			       struct btrfs_trans_handle *trans,
674			       u64 bytenr, u64 num_bytes,
675			       u64 parent, u64 ref_root,
676			       u64 owner, u64 offset, int action,
677			       struct btrfs_delayed_extent_op *extent_op,
678			       int for_cow)
679{
680	struct btrfs_delayed_data_ref *ref;
681	struct btrfs_delayed_ref_head *head_ref;
682	struct btrfs_delayed_ref_root *delayed_refs;
 
683
684	BUG_ON(extent_op && !extent_op->is_data);
685	ref = kmalloc(sizeof(*ref), GFP_NOFS);
686	if (!ref)
687		return -ENOMEM;
688
689	head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
690	if (!head_ref) {
691		kfree(ref);
692		return -ENOMEM;
693	}
694
695	head_ref->extent_op = extent_op;
696
697	delayed_refs = &trans->transaction->delayed_refs;
698	spin_lock(&delayed_refs->lock);
699
700	/*
701	 * insert both the head node and the new ref without dropping
702	 * the spin lock
703	 */
704	add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
705				   num_bytes, action, 1);
706
707	add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
708				   num_bytes, parent, ref_root, owner, offset,
709				   action, for_cow);
710	if (!is_fstree(ref_root) &&
711	    waitqueue_active(&delayed_refs->seq_wait))
712		wake_up(&delayed_refs->seq_wait);
713	spin_unlock(&delayed_refs->lock);
714
715	return 0;
716}
717
718int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
719				struct btrfs_trans_handle *trans,
720				u64 bytenr, u64 num_bytes,
721				struct btrfs_delayed_extent_op *extent_op)
722{
723	struct btrfs_delayed_ref_head *head_ref;
724	struct btrfs_delayed_ref_root *delayed_refs;
 
725
726	head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
727	if (!head_ref)
728		return -ENOMEM;
729
730	head_ref->extent_op = extent_op;
731
732	delayed_refs = &trans->transaction->delayed_refs;
733	spin_lock(&delayed_refs->lock);
734
735	add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
736				   num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
737				   extent_op->is_data);
 
738
739	if (waitqueue_active(&delayed_refs->seq_wait))
740		wake_up(&delayed_refs->seq_wait);
741	spin_unlock(&delayed_refs->lock);
742	return 0;
743}
744
745/*
746 * this does a simple search for the head node for a given extent.
747 * It must be called with the delayed ref spinlock held, and it returns
748 * the head node if any where found, or NULL if not.
749 */
750struct btrfs_delayed_ref_head *
751btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
752{
753	struct btrfs_delayed_ref_node *ref;
754	struct btrfs_delayed_ref_root *delayed_refs;
755
756	delayed_refs = &trans->transaction->delayed_refs;
757	ref = find_ref_head(&delayed_refs->root, bytenr, NULL, 0);
758	if (ref)
759		return btrfs_delayed_node_to_head(ref);
760	return NULL;
761}
v3.1
  1/*
  2 * Copyright (C) 2009 Oracle.  All rights reserved.
  3 *
  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.
  7 *
  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.
 12 *
 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.
 17 */
 18
 19#include <linux/sched.h>
 20#include <linux/slab.h>
 21#include <linux/sort.h>
 22#include "ctree.h"
 23#include "delayed-ref.h"
 24#include "transaction.h"
 25
 26/*
 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.
 33 */
 34
 35/*
 36 * compare two delayed tree backrefs with same bytenr and type
 37 */
 38static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref2,
 39			  struct btrfs_delayed_tree_ref *ref1)
 40{
 41	if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) {
 42		if (ref1->root < ref2->root)
 43			return -1;
 44		if (ref1->root > ref2->root)
 45			return 1;
 46	} else {
 47		if (ref1->parent < ref2->parent)
 48			return -1;
 49		if (ref1->parent > ref2->parent)
 50			return 1;
 51	}
 52	return 0;
 53}
 54
 55/*
 56 * compare two delayed data backrefs with same bytenr and type
 57 */
 58static int comp_data_refs(struct btrfs_delayed_data_ref *ref2,
 59			  struct btrfs_delayed_data_ref *ref1)
 60{
 61	if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
 62		if (ref1->root < ref2->root)
 63			return -1;
 64		if (ref1->root > ref2->root)
 65			return 1;
 66		if (ref1->objectid < ref2->objectid)
 67			return -1;
 68		if (ref1->objectid > ref2->objectid)
 69			return 1;
 70		if (ref1->offset < ref2->offset)
 71			return -1;
 72		if (ref1->offset > ref2->offset)
 73			return 1;
 74	} else {
 75		if (ref1->parent < ref2->parent)
 76			return -1;
 77		if (ref1->parent > ref2->parent)
 78			return 1;
 79	}
 80	return 0;
 81}
 82
 83/*
 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.
 86 */
 87static int comp_entry(struct btrfs_delayed_ref_node *ref2,
 88		      struct btrfs_delayed_ref_node *ref1)
 89{
 90	if (ref1->bytenr < ref2->bytenr)
 91		return -1;
 92	if (ref1->bytenr > ref2->bytenr)
 93		return 1;
 94	if (ref1->is_head && ref2->is_head)
 95		return 0;
 96	if (ref2->is_head)
 97		return -1;
 98	if (ref1->is_head)
 99		return 1;
100	if (ref1->type < ref2->type)
101		return -1;
102	if (ref1->type > ref2->type)
103		return 1;
 
 
 
 
 
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));
112	}
113	BUG();
114	return 0;
115}
116
117/*
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
120 * inserted.
121 */
122static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root,
123						  struct rb_node *node)
124{
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;
129	int cmp;
130
131	ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
132	while (*p) {
133		parent_node = *p;
134		entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
135				 rb_node);
136
137		cmp = comp_entry(entry, ins);
138		if (cmp < 0)
139			p = &(*p)->rb_left;
140		else if (cmp > 0)
141			p = &(*p)->rb_right;
142		else
143			return entry;
144	}
145
146	rb_link_node(node, parent_node, p);
147	rb_insert_color(node, root);
148	return NULL;
149}
150
151/*
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
 
 
154 */
155static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root,
156				  u64 bytenr,
157				  struct btrfs_delayed_ref_node **last)
 
158{
159	struct rb_node *n = root->rb_node;
160	struct btrfs_delayed_ref_node *entry;
161	int cmp;
162
 
 
 
163	while (n) {
164		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
165		WARN_ON(!entry->in_tree);
166		if (last)
167			*last = entry;
168
169		if (bytenr < entry->bytenr)
170			cmp = -1;
171		else if (bytenr > entry->bytenr)
172			cmp = 1;
173		else if (!btrfs_delayed_ref_is_head(entry))
174			cmp = 1;
175		else
176			cmp = 0;
177
178		if (cmp < 0)
179			n = n->rb_left;
180		else if (cmp > 0)
181			n = n->rb_right;
182		else
183			return entry;
184	}
 
 
 
 
 
 
 
 
 
 
 
 
 
185	return NULL;
186}
187
188int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
189			   struct btrfs_delayed_ref_head *head)
190{
191	struct btrfs_delayed_ref_root *delayed_refs;
192
193	delayed_refs = &trans->transaction->delayed_refs;
194	assert_spin_locked(&delayed_refs->lock);
195	if (mutex_trylock(&head->mutex))
196		return 0;
197
198	atomic_inc(&head->node.refs);
199	spin_unlock(&delayed_refs->lock);
200
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);
206		return -EAGAIN;
207	}
208	btrfs_put_delayed_ref(&head->node);
209	return 0;
210}
211
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
212int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
213			   struct list_head *cluster, u64 start)
214{
215	int count = 0;
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;
220
221	delayed_refs = &trans->transaction->delayed_refs;
222	if (start == 0) {
223		node = rb_first(&delayed_refs->root);
224	} else {
225		ref = NULL;
226		find_ref_head(&delayed_refs->root, start, &ref);
227		if (ref) {
228			struct btrfs_delayed_ref_node *tmp;
229
230			node = rb_prev(&ref->rb_node);
231			while (node) {
232				tmp = rb_entry(node,
233					       struct btrfs_delayed_ref_node,
234					       rb_node);
235				if (tmp->bytenr < start)
236					break;
237				ref = tmp;
238				node = rb_prev(&ref->rb_node);
239			}
240			node = &ref->rb_node;
241		} else
242			node = rb_first(&delayed_refs->root);
243	}
244again:
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 =
252					head->node.bytenr;
253				count++;
254
255				WARN_ON(delayed_refs->num_heads_ready == 0);
256				delayed_refs->num_heads_ready--;
257			} else if (count) {
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
263				 */
264				break;
265			}
266		}
267		node = rb_next(node);
268	}
269	if (count) {
270		return 0;
271	} else if (start) {
272		/*
273		 * we've gone to the end of the rbtree without finding any
274		 * clusters.  start from the beginning and try again
275		 */
276		start = 0;
277		node = rb_first(&delayed_refs->root);
278		goto again;
279	}
280	return 1;
281}
282
283/*
284 * helper function to update an extent delayed ref in the
285 * rbtree.  existing and update must both have the same
286 * bytenr and parent
287 *
288 * This may free existing if the update cancels out whatever
289 * operation it was doing.
290 */
291static noinline void
292update_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)
296{
297	if (update->action != existing->action) {
298		/*
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.
303		 */
304		existing->ref_mod--;
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--;
313		} else {
314			WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
315				existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
316		}
317	} else {
318		WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
319			existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
320		/*
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
325		 * reference count
326		 */
327		existing->ref_mod += update->ref_mod;
328	}
329}
330
331/*
332 * helper function to update the accounting in the head ref
333 * existing and update must have the same bytenr
334 */
335static noinline void
336update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
337			 struct btrfs_delayed_ref_node *update)
338{
339	struct btrfs_delayed_ref_head *existing_ref;
340	struct btrfs_delayed_ref_head *ref;
341
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);
345
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.
352		 * Set it again here
353		 */
354		existing_ref->must_insert_reserved = ref->must_insert_reserved;
355
356		/*
357		 * update the num_bytes so we make sure the accounting
358		 * is done correctly
359		 */
360		existing->num_bytes = update->num_bytes;
361
362	}
363
364	if (ref->extent_op) {
365		if (!existing_ref->extent_op) {
366			existing_ref->extent_op = ref->extent_op;
367		} else {
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;
373			}
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;
378			}
379			kfree(ref->extent_op);
380		}
381	}
382	/*
383	 * update the reference mod on the head to reflect this new operation
384	 */
385	existing->ref_mod += update->ref_mod;
386}
387
388/*
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.
392 */
393static noinline int add_delayed_ref_head(struct btrfs_trans_handle *trans,
 
394					struct btrfs_delayed_ref_node *ref,
395					u64 bytenr, u64 num_bytes,
396					int action, int is_data)
397{
398	struct btrfs_delayed_ref_node *existing;
399	struct btrfs_delayed_ref_head *head_ref = NULL;
400	struct btrfs_delayed_ref_root *delayed_refs;
401	int count_mod = 1;
402	int must_insert_reserved = 0;
403
404	/*
405	 * the head node stores the sum of all the mods, so dropping a ref
406	 * should drop the sum in the head node by one.
407	 */
408	if (action == BTRFS_UPDATE_DELAYED_HEAD)
409		count_mod = 0;
410	else if (action == BTRFS_DROP_DELAYED_REF)
411		count_mod = -1;
412
413	/*
414	 * BTRFS_ADD_DELAYED_EXTENT means that we need to update
415	 * the reserved accounting when the extent is finally added, or
416	 * if a later modification deletes the delayed ref without ever
417	 * inserting the extent into the extent allocation tree.
418	 * ref->must_insert_reserved is the flag used to record
419	 * that accounting mods are required.
420	 *
421	 * Once we record must_insert_reserved, switch the action to
422	 * BTRFS_ADD_DELAYED_REF because other special casing is not required.
423	 */
424	if (action == BTRFS_ADD_DELAYED_EXTENT)
425		must_insert_reserved = 1;
426	else
427		must_insert_reserved = 0;
428
429	delayed_refs = &trans->transaction->delayed_refs;
430
431	/* first set the basic ref node struct up */
432	atomic_set(&ref->refs, 1);
433	ref->bytenr = bytenr;
434	ref->num_bytes = num_bytes;
435	ref->ref_mod = count_mod;
436	ref->type  = 0;
437	ref->action  = 0;
438	ref->is_head = 1;
439	ref->in_tree = 1;
 
440
441	head_ref = btrfs_delayed_node_to_head(ref);
442	head_ref->must_insert_reserved = must_insert_reserved;
443	head_ref->is_data = is_data;
444
445	INIT_LIST_HEAD(&head_ref->cluster);
446	mutex_init(&head_ref->mutex);
447
448	trace_btrfs_delayed_ref_head(ref, head_ref, action);
449
450	existing = tree_insert(&delayed_refs->root, &ref->rb_node);
451
452	if (existing) {
453		update_existing_head_ref(existing, ref);
454		/*
455		 * we've updated the existing ref, free the newly
456		 * allocated ref
457		 */
458		kfree(ref);
459	} else {
460		delayed_refs->num_heads++;
461		delayed_refs->num_heads_ready++;
462		delayed_refs->num_entries++;
463		trans->delayed_ref_updates++;
464	}
465	return 0;
466}
467
468/*
469 * helper to insert a delayed tree ref into the rbtree.
470 */
471static noinline int add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 
472					 struct btrfs_delayed_ref_node *ref,
473					 u64 bytenr, u64 num_bytes, u64 parent,
474					 u64 ref_root, int level, int action)
 
475{
476	struct btrfs_delayed_ref_node *existing;
477	struct btrfs_delayed_tree_ref *full_ref;
478	struct btrfs_delayed_ref_root *delayed_refs;
 
479
480	if (action == BTRFS_ADD_DELAYED_EXTENT)
481		action = BTRFS_ADD_DELAYED_REF;
482
483	delayed_refs = &trans->transaction->delayed_refs;
484
485	/* first set the basic ref node struct up */
486	atomic_set(&ref->refs, 1);
487	ref->bytenr = bytenr;
488	ref->num_bytes = num_bytes;
489	ref->ref_mod = 1;
490	ref->action = action;
491	ref->is_head = 0;
492	ref->in_tree = 1;
493
 
 
 
 
494	full_ref = btrfs_delayed_node_to_tree_ref(ref);
495	if (parent) {
496		full_ref->parent = parent;
 
497		ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
498	} else {
499		full_ref->root = ref_root;
500		ref->type = BTRFS_TREE_BLOCK_REF_KEY;
501	}
502	full_ref->level = level;
503
504	trace_btrfs_delayed_tree_ref(ref, full_ref, action);
505
506	existing = tree_insert(&delayed_refs->root, &ref->rb_node);
507
508	if (existing) {
509		update_existing_ref(trans, delayed_refs, existing, ref);
510		/*
511		 * we've updated the existing ref, free the newly
512		 * allocated ref
513		 */
514		kfree(ref);
515	} else {
516		delayed_refs->num_entries++;
517		trans->delayed_ref_updates++;
518	}
519	return 0;
520}
521
522/*
523 * helper to insert a delayed data ref into the rbtree.
524 */
525static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans,
 
526					 struct btrfs_delayed_ref_node *ref,
527					 u64 bytenr, u64 num_bytes, u64 parent,
528					 u64 ref_root, u64 owner, u64 offset,
529					 int action)
530{
531	struct btrfs_delayed_ref_node *existing;
532	struct btrfs_delayed_data_ref *full_ref;
533	struct btrfs_delayed_ref_root *delayed_refs;
 
534
535	if (action == BTRFS_ADD_DELAYED_EXTENT)
536		action = BTRFS_ADD_DELAYED_REF;
537
538	delayed_refs = &trans->transaction->delayed_refs;
539
540	/* first set the basic ref node struct up */
541	atomic_set(&ref->refs, 1);
542	ref->bytenr = bytenr;
543	ref->num_bytes = num_bytes;
544	ref->ref_mod = 1;
545	ref->action = action;
546	ref->is_head = 0;
547	ref->in_tree = 1;
548
 
 
 
 
549	full_ref = btrfs_delayed_node_to_data_ref(ref);
550	if (parent) {
551		full_ref->parent = parent;
 
552		ref->type = BTRFS_SHARED_DATA_REF_KEY;
553	} else {
554		full_ref->root = ref_root;
555		ref->type = BTRFS_EXTENT_DATA_REF_KEY;
556	}
557	full_ref->objectid = owner;
558	full_ref->offset = offset;
559
560	trace_btrfs_delayed_data_ref(ref, full_ref, action);
561
562	existing = tree_insert(&delayed_refs->root, &ref->rb_node);
563
564	if (existing) {
565		update_existing_ref(trans, delayed_refs, existing, ref);
566		/*
567		 * we've updated the existing ref, free the newly
568		 * allocated ref
569		 */
570		kfree(ref);
571	} else {
572		delayed_refs->num_entries++;
573		trans->delayed_ref_updates++;
574	}
575	return 0;
576}
577
578/*
579 * add a delayed tree ref.  This does all of the accounting required
580 * to make sure the delayed ref is eventually processed before this
581 * transaction commits.
582 */
583int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 
584			       u64 bytenr, u64 num_bytes, u64 parent,
585			       u64 ref_root,  int level, int action,
586			       struct btrfs_delayed_extent_op *extent_op)
 
587{
588	struct btrfs_delayed_tree_ref *ref;
589	struct btrfs_delayed_ref_head *head_ref;
590	struct btrfs_delayed_ref_root *delayed_refs;
591	int ret;
592
593	BUG_ON(extent_op && extent_op->is_data);
594	ref = kmalloc(sizeof(*ref), GFP_NOFS);
595	if (!ref)
596		return -ENOMEM;
597
598	head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
599	if (!head_ref) {
600		kfree(ref);
601		return -ENOMEM;
602	}
603
604	head_ref->extent_op = extent_op;
605
606	delayed_refs = &trans->transaction->delayed_refs;
607	spin_lock(&delayed_refs->lock);
608
609	/*
610	 * insert both the head node and the new ref without dropping
611	 * the spin lock
612	 */
613	ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
614				   action, 0);
615	BUG_ON(ret);
616
617	ret = add_delayed_tree_ref(trans, &ref->node, bytenr, num_bytes,
618				   parent, ref_root, level, action);
619	BUG_ON(ret);
 
 
620	spin_unlock(&delayed_refs->lock);
 
621	return 0;
622}
623
624/*
625 * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
626 */
627int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 
628			       u64 bytenr, u64 num_bytes,
629			       u64 parent, u64 ref_root,
630			       u64 owner, u64 offset, int action,
631			       struct btrfs_delayed_extent_op *extent_op)
 
632{
633	struct btrfs_delayed_data_ref *ref;
634	struct btrfs_delayed_ref_head *head_ref;
635	struct btrfs_delayed_ref_root *delayed_refs;
636	int ret;
637
638	BUG_ON(extent_op && !extent_op->is_data);
639	ref = kmalloc(sizeof(*ref), GFP_NOFS);
640	if (!ref)
641		return -ENOMEM;
642
643	head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
644	if (!head_ref) {
645		kfree(ref);
646		return -ENOMEM;
647	}
648
649	head_ref->extent_op = extent_op;
650
651	delayed_refs = &trans->transaction->delayed_refs;
652	spin_lock(&delayed_refs->lock);
653
654	/*
655	 * insert both the head node and the new ref without dropping
656	 * the spin lock
657	 */
658	ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
659				   action, 1);
660	BUG_ON(ret);
661
662	ret = add_delayed_data_ref(trans, &ref->node, bytenr, num_bytes,
663				   parent, ref_root, owner, offset, action);
664	BUG_ON(ret);
 
 
665	spin_unlock(&delayed_refs->lock);
 
666	return 0;
667}
668
669int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
 
670				u64 bytenr, u64 num_bytes,
671				struct btrfs_delayed_extent_op *extent_op)
672{
673	struct btrfs_delayed_ref_head *head_ref;
674	struct btrfs_delayed_ref_root *delayed_refs;
675	int ret;
676
677	head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
678	if (!head_ref)
679		return -ENOMEM;
680
681	head_ref->extent_op = extent_op;
682
683	delayed_refs = &trans->transaction->delayed_refs;
684	spin_lock(&delayed_refs->lock);
685
686	ret = add_delayed_ref_head(trans, &head_ref->node, bytenr,
687				   num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
688				   extent_op->is_data);
689	BUG_ON(ret);
690
 
 
691	spin_unlock(&delayed_refs->lock);
692	return 0;
693}
694
695/*
696 * this does a simple search for the head node for a given extent.
697 * It must be called with the delayed ref spinlock held, and it returns
698 * the head node if any where found, or NULL if not.
699 */
700struct btrfs_delayed_ref_head *
701btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
702{
703	struct btrfs_delayed_ref_node *ref;
704	struct btrfs_delayed_ref_root *delayed_refs;
705
706	delayed_refs = &trans->transaction->delayed_refs;
707	ref = find_ref_head(&delayed_refs->root, bytenr, NULL);
708	if (ref)
709		return btrfs_delayed_node_to_head(ref);
710	return NULL;
711}