Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux...
[~shefty/rdma-dev.git] / fs / btrfs / delayed-ref.c
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  */
38 static 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  */
58 static 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  */
87 static 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  */
127 static 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  */
162 static 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
171 again:
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
212 int 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
236 int 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
254 int 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         }
274 again:
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  */
321 static noinline void
322 update_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  */
365 static noinline void
366 update_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  */
423 static noinline int 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(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         return 0;
498 }
499
500 /*
501  * helper to insert a delayed tree ref into the rbtree.
502  */
503 static noinline int add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
504                                          struct btrfs_trans_handle *trans,
505                                          struct btrfs_delayed_ref_node *ref,
506                                          u64 bytenr, u64 num_bytes, u64 parent,
507                                          u64 ref_root, int level, int action,
508                                          int for_cow)
509 {
510         struct btrfs_delayed_ref_node *existing;
511         struct btrfs_delayed_tree_ref *full_ref;
512         struct btrfs_delayed_ref_root *delayed_refs;
513         u64 seq = 0;
514
515         if (action == BTRFS_ADD_DELAYED_EXTENT)
516                 action = BTRFS_ADD_DELAYED_REF;
517
518         delayed_refs = &trans->transaction->delayed_refs;
519
520         /* first set the basic ref node struct up */
521         atomic_set(&ref->refs, 1);
522         ref->bytenr = bytenr;
523         ref->num_bytes = num_bytes;
524         ref->ref_mod = 1;
525         ref->action = action;
526         ref->is_head = 0;
527         ref->in_tree = 1;
528
529         if (need_ref_seq(for_cow, ref_root))
530                 seq = inc_delayed_seq(delayed_refs);
531         ref->seq = seq;
532
533         full_ref = btrfs_delayed_node_to_tree_ref(ref);
534         full_ref->parent = parent;
535         full_ref->root = ref_root;
536         if (parent)
537                 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
538         else
539                 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
540         full_ref->level = level;
541
542         trace_btrfs_delayed_tree_ref(ref, full_ref, action);
543
544         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
545
546         if (existing) {
547                 update_existing_ref(trans, delayed_refs, existing, ref);
548                 /*
549                  * we've updated the existing ref, free the newly
550                  * allocated ref
551                  */
552                 kfree(ref);
553         } else {
554                 delayed_refs->num_entries++;
555                 trans->delayed_ref_updates++;
556         }
557         return 0;
558 }
559
560 /*
561  * helper to insert a delayed data ref into the rbtree.
562  */
563 static noinline int add_delayed_data_ref(struct btrfs_fs_info *fs_info,
564                                          struct btrfs_trans_handle *trans,
565                                          struct btrfs_delayed_ref_node *ref,
566                                          u64 bytenr, u64 num_bytes, u64 parent,
567                                          u64 ref_root, u64 owner, u64 offset,
568                                          int action, int for_cow)
569 {
570         struct btrfs_delayed_ref_node *existing;
571         struct btrfs_delayed_data_ref *full_ref;
572         struct btrfs_delayed_ref_root *delayed_refs;
573         u64 seq = 0;
574
575         if (action == BTRFS_ADD_DELAYED_EXTENT)
576                 action = BTRFS_ADD_DELAYED_REF;
577
578         delayed_refs = &trans->transaction->delayed_refs;
579
580         /* first set the basic ref node struct up */
581         atomic_set(&ref->refs, 1);
582         ref->bytenr = bytenr;
583         ref->num_bytes = num_bytes;
584         ref->ref_mod = 1;
585         ref->action = action;
586         ref->is_head = 0;
587         ref->in_tree = 1;
588
589         if (need_ref_seq(for_cow, ref_root))
590                 seq = inc_delayed_seq(delayed_refs);
591         ref->seq = seq;
592
593         full_ref = btrfs_delayed_node_to_data_ref(ref);
594         full_ref->parent = parent;
595         full_ref->root = ref_root;
596         if (parent)
597                 ref->type = BTRFS_SHARED_DATA_REF_KEY;
598         else
599                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
600
601         full_ref->objectid = owner;
602         full_ref->offset = offset;
603
604         trace_btrfs_delayed_data_ref(ref, full_ref, action);
605
606         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
607
608         if (existing) {
609                 update_existing_ref(trans, delayed_refs, existing, ref);
610                 /*
611                  * we've updated the existing ref, free the newly
612                  * allocated ref
613                  */
614                 kfree(ref);
615         } else {
616                 delayed_refs->num_entries++;
617                 trans->delayed_ref_updates++;
618         }
619         return 0;
620 }
621
622 /*
623  * add a delayed tree ref.  This does all of the accounting required
624  * to make sure the delayed ref is eventually processed before this
625  * transaction commits.
626  */
627 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
628                                struct btrfs_trans_handle *trans,
629                                u64 bytenr, u64 num_bytes, u64 parent,
630                                u64 ref_root,  int level, int action,
631                                struct btrfs_delayed_extent_op *extent_op,
632                                int for_cow)
633 {
634         struct btrfs_delayed_tree_ref *ref;
635         struct btrfs_delayed_ref_head *head_ref;
636         struct btrfs_delayed_ref_root *delayed_refs;
637         int ret;
638
639         BUG_ON(extent_op && extent_op->is_data);
640         ref = kmalloc(sizeof(*ref), GFP_NOFS);
641         if (!ref)
642                 return -ENOMEM;
643
644         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
645         if (!head_ref) {
646                 kfree(ref);
647                 return -ENOMEM;
648         }
649
650         head_ref->extent_op = extent_op;
651
652         delayed_refs = &trans->transaction->delayed_refs;
653         spin_lock(&delayed_refs->lock);
654
655         /*
656          * insert both the head node and the new ref without dropping
657          * the spin lock
658          */
659         ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
660                                    num_bytes, action, 0);
661         BUG_ON(ret);
662
663         ret = add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
664                                    num_bytes, parent, ref_root, level, action,
665                                    for_cow);
666         BUG_ON(ret);
667         if (!need_ref_seq(for_cow, ref_root) &&
668             waitqueue_active(&delayed_refs->seq_wait))
669                 wake_up(&delayed_refs->seq_wait);
670         spin_unlock(&delayed_refs->lock);
671         return 0;
672 }
673
674 /*
675  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
676  */
677 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
678                                struct btrfs_trans_handle *trans,
679                                u64 bytenr, u64 num_bytes,
680                                u64 parent, u64 ref_root,
681                                u64 owner, u64 offset, int action,
682                                struct btrfs_delayed_extent_op *extent_op,
683                                int for_cow)
684 {
685         struct btrfs_delayed_data_ref *ref;
686         struct btrfs_delayed_ref_head *head_ref;
687         struct btrfs_delayed_ref_root *delayed_refs;
688         int ret;
689
690         BUG_ON(extent_op && !extent_op->is_data);
691         ref = kmalloc(sizeof(*ref), GFP_NOFS);
692         if (!ref)
693                 return -ENOMEM;
694
695         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
696         if (!head_ref) {
697                 kfree(ref);
698                 return -ENOMEM;
699         }
700
701         head_ref->extent_op = extent_op;
702
703         delayed_refs = &trans->transaction->delayed_refs;
704         spin_lock(&delayed_refs->lock);
705
706         /*
707          * insert both the head node and the new ref without dropping
708          * the spin lock
709          */
710         ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
711                                    num_bytes, action, 1);
712         BUG_ON(ret);
713
714         ret = add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
715                                    num_bytes, parent, ref_root, owner, offset,
716                                    action, for_cow);
717         BUG_ON(ret);
718         if (!need_ref_seq(for_cow, ref_root) &&
719             waitqueue_active(&delayed_refs->seq_wait))
720                 wake_up(&delayed_refs->seq_wait);
721         spin_unlock(&delayed_refs->lock);
722         return 0;
723 }
724
725 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
726                                 struct btrfs_trans_handle *trans,
727                                 u64 bytenr, u64 num_bytes,
728                                 struct btrfs_delayed_extent_op *extent_op)
729 {
730         struct btrfs_delayed_ref_head *head_ref;
731         struct btrfs_delayed_ref_root *delayed_refs;
732         int ret;
733
734         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
735         if (!head_ref)
736                 return -ENOMEM;
737
738         head_ref->extent_op = extent_op;
739
740         delayed_refs = &trans->transaction->delayed_refs;
741         spin_lock(&delayed_refs->lock);
742
743         ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
744                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
745                                    extent_op->is_data);
746         BUG_ON(ret);
747
748         if (waitqueue_active(&delayed_refs->seq_wait))
749                 wake_up(&delayed_refs->seq_wait);
750         spin_unlock(&delayed_refs->lock);
751         return 0;
752 }
753
754 /*
755  * this does a simple search for the head node for a given extent.
756  * It must be called with the delayed ref spinlock held, and it returns
757  * the head node if any where found, or NULL if not.
758  */
759 struct btrfs_delayed_ref_head *
760 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
761 {
762         struct btrfs_delayed_ref_node *ref;
763         struct btrfs_delayed_ref_root *delayed_refs;
764
765         delayed_refs = &trans->transaction->delayed_refs;
766         ref = find_ref_head(&delayed_refs->root, bytenr, NULL, 0);
767         if (ref)
768                 return btrfs_delayed_node_to_head(ref);
769         return NULL;
770 }