Commit | Line | Data |
---|---|---|
56bec294 CM |
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/sort.h> | |
21 | #include <linux/ftrace.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 | * Right now this code is only used for reference counted trees, but | |
35 | * the long term goal is to get rid of the similar code for delayed | |
36 | * extent tree modifications. | |
37 | */ | |
38 | ||
39 | /* | |
40 | * entries in the rb tree are ordered by the byte number of the extent | |
41 | * and by the byte number of the parent block. | |
42 | */ | |
43 | static int comp_entry(struct btrfs_delayed_ref_node *ref, | |
44 | u64 bytenr, u64 parent) | |
45 | { | |
46 | if (bytenr < ref->bytenr) | |
47 | return -1; | |
48 | if (bytenr > ref->bytenr) | |
49 | return 1; | |
50 | if (parent < ref->parent) | |
51 | return -1; | |
52 | if (parent > ref->parent) | |
53 | return 1; | |
54 | return 0; | |
55 | } | |
56 | ||
57 | /* | |
58 | * insert a new ref into the rbtree. This returns any existing refs | |
59 | * for the same (bytenr,parent) tuple, or NULL if the new node was properly | |
60 | * inserted. | |
61 | */ | |
62 | static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root, | |
63 | u64 bytenr, u64 parent, | |
64 | struct rb_node *node) | |
65 | { | |
66 | struct rb_node **p = &root->rb_node; | |
67 | struct rb_node *parent_node = NULL; | |
68 | struct btrfs_delayed_ref_node *entry; | |
69 | int cmp; | |
70 | ||
71 | while (*p) { | |
72 | parent_node = *p; | |
73 | entry = rb_entry(parent_node, struct btrfs_delayed_ref_node, | |
74 | rb_node); | |
75 | ||
76 | cmp = comp_entry(entry, bytenr, parent); | |
77 | if (cmp < 0) | |
78 | p = &(*p)->rb_left; | |
79 | else if (cmp > 0) | |
80 | p = &(*p)->rb_right; | |
81 | else | |
82 | return entry; | |
83 | } | |
84 | ||
85 | entry = rb_entry(node, struct btrfs_delayed_ref_node, rb_node); | |
86 | rb_link_node(node, parent_node, p); | |
87 | rb_insert_color(node, root); | |
88 | return NULL; | |
89 | } | |
90 | ||
91 | /* | |
92 | * find an entry based on (bytenr,parent). This returns the delayed | |
93 | * ref if it was able to find one, or NULL if nothing was in that spot | |
94 | */ | |
95 | static struct btrfs_delayed_ref_node *tree_search(struct rb_root *root, | |
c3e69d58 CM |
96 | u64 bytenr, u64 parent, |
97 | struct btrfs_delayed_ref_node **last) | |
56bec294 CM |
98 | { |
99 | struct rb_node *n = root->rb_node; | |
100 | struct btrfs_delayed_ref_node *entry; | |
101 | int cmp; | |
102 | ||
103 | while (n) { | |
104 | entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node); | |
105 | WARN_ON(!entry->in_tree); | |
c3e69d58 CM |
106 | if (last) |
107 | *last = entry; | |
56bec294 CM |
108 | |
109 | cmp = comp_entry(entry, bytenr, parent); | |
110 | if (cmp < 0) | |
111 | n = n->rb_left; | |
112 | else if (cmp > 0) | |
113 | n = n->rb_right; | |
114 | else | |
115 | return entry; | |
116 | } | |
117 | return NULL; | |
118 | } | |
119 | ||
c3e69d58 CM |
120 | int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans, |
121 | struct btrfs_delayed_ref_head *head) | |
56bec294 | 122 | { |
c3e69d58 CM |
123 | struct btrfs_delayed_ref_root *delayed_refs; |
124 | ||
125 | delayed_refs = &trans->transaction->delayed_refs; | |
126 | assert_spin_locked(&delayed_refs->lock); | |
127 | if (mutex_trylock(&head->mutex)) | |
128 | return 0; | |
129 | ||
130 | atomic_inc(&head->node.refs); | |
131 | spin_unlock(&delayed_refs->lock); | |
132 | ||
133 | mutex_lock(&head->mutex); | |
134 | spin_lock(&delayed_refs->lock); | |
135 | if (!head->node.in_tree) { | |
136 | mutex_unlock(&head->mutex); | |
137 | btrfs_put_delayed_ref(&head->node); | |
138 | return -EAGAIN; | |
139 | } | |
140 | btrfs_put_delayed_ref(&head->node); | |
141 | return 0; | |
142 | } | |
143 | ||
144 | int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans, | |
145 | struct list_head *cluster, u64 start) | |
146 | { | |
147 | int count = 0; | |
148 | struct btrfs_delayed_ref_root *delayed_refs; | |
56bec294 | 149 | struct rb_node *node; |
c3e69d58 | 150 | struct btrfs_delayed_ref_node *ref; |
56bec294 | 151 | struct btrfs_delayed_ref_head *head; |
56bec294 | 152 | |
c3e69d58 CM |
153 | delayed_refs = &trans->transaction->delayed_refs; |
154 | if (start == 0) { | |
155 | node = rb_first(&delayed_refs->root); | |
156 | } else { | |
157 | ref = NULL; | |
158 | tree_search(&delayed_refs->root, start, (u64)-1, &ref); | |
159 | if (ref) { | |
160 | struct btrfs_delayed_ref_node *tmp; | |
161 | ||
162 | node = rb_prev(&ref->rb_node); | |
163 | while (node) { | |
164 | tmp = rb_entry(node, | |
165 | struct btrfs_delayed_ref_node, | |
166 | rb_node); | |
167 | if (tmp->bytenr < start) | |
168 | break; | |
169 | ref = tmp; | |
170 | node = rb_prev(&ref->rb_node); | |
171 | } | |
172 | node = &ref->rb_node; | |
173 | } else | |
174 | node = rb_first(&delayed_refs->root); | |
175 | } | |
176 | again: | |
177 | while (node && count < 32) { | |
178 | ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node); | |
56bec294 CM |
179 | if (btrfs_delayed_ref_is_head(ref)) { |
180 | head = btrfs_delayed_node_to_head(ref); | |
c3e69d58 CM |
181 | if (list_empty(&head->cluster)) { |
182 | list_add_tail(&head->cluster, cluster); | |
183 | delayed_refs->run_delayed_start = | |
184 | head->node.bytenr; | |
185 | count++; | |
186 | ||
187 | WARN_ON(delayed_refs->num_heads_ready == 0); | |
188 | delayed_refs->num_heads_ready--; | |
189 | } else if (count) { | |
190 | /* the goal of the clustering is to find extents | |
191 | * that are likely to end up in the same extent | |
192 | * leaf on disk. So, we don't want them spread | |
193 | * all over the tree. Stop now if we've hit | |
194 | * a head that was already in use | |
195 | */ | |
56bec294 CM |
196 | break; |
197 | } | |
198 | } | |
c3e69d58 | 199 | node = rb_next(node); |
56bec294 | 200 | } |
c3e69d58 CM |
201 | if (count) { |
202 | return 0; | |
203 | } else if (start) { | |
204 | /* | |
205 | * we've gone to the end of the rbtree without finding any | |
206 | * clusters. start from the beginning and try again | |
207 | */ | |
208 | start = 0; | |
209 | node = rb_first(&delayed_refs->root); | |
210 | goto again; | |
211 | } | |
212 | return 1; | |
56bec294 CM |
213 | } |
214 | ||
215 | /* | |
216 | * This checks to see if there are any delayed refs in the | |
217 | * btree for a given bytenr. It returns one if it finds any | |
218 | * and zero otherwise. | |
219 | * | |
220 | * If it only finds a head node, it returns 0. | |
221 | * | |
222 | * The idea is to use this when deciding if you can safely delete an | |
223 | * extent from the extent allocation tree. There may be a pending | |
224 | * ref in the rbtree that adds or removes references, so as long as this | |
225 | * returns one you need to leave the BTRFS_EXTENT_ITEM in the extent | |
226 | * allocation tree. | |
227 | */ | |
228 | int btrfs_delayed_ref_pending(struct btrfs_trans_handle *trans, u64 bytenr) | |
229 | { | |
230 | struct btrfs_delayed_ref_node *ref; | |
231 | struct btrfs_delayed_ref_root *delayed_refs; | |
232 | struct rb_node *prev_node; | |
233 | int ret = 0; | |
234 | ||
235 | delayed_refs = &trans->transaction->delayed_refs; | |
236 | spin_lock(&delayed_refs->lock); | |
237 | ||
c3e69d58 | 238 | ref = tree_search(&delayed_refs->root, bytenr, (u64)-1, NULL); |
56bec294 CM |
239 | if (ref) { |
240 | prev_node = rb_prev(&ref->rb_node); | |
241 | if (!prev_node) | |
242 | goto out; | |
243 | ref = rb_entry(prev_node, struct btrfs_delayed_ref_node, | |
244 | rb_node); | |
245 | if (ref->bytenr == bytenr) | |
246 | ret = 1; | |
247 | } | |
248 | out: | |
249 | spin_unlock(&delayed_refs->lock); | |
250 | return ret; | |
251 | } | |
252 | ||
253 | /* | |
254 | * helper function to lookup reference count | |
255 | * | |
256 | * the head node for delayed ref is used to store the sum of all the | |
257 | * reference count modifications queued up in the rbtree. This way you | |
258 | * can check to see what the reference count would be if all of the | |
259 | * delayed refs are processed. | |
260 | */ | |
261 | int btrfs_lookup_extent_ref(struct btrfs_trans_handle *trans, | |
262 | struct btrfs_root *root, u64 bytenr, | |
263 | u64 num_bytes, u32 *refs) | |
264 | { | |
265 | struct btrfs_delayed_ref_node *ref; | |
266 | struct btrfs_delayed_ref_head *head; | |
267 | struct btrfs_delayed_ref_root *delayed_refs; | |
268 | struct btrfs_path *path; | |
269 | struct extent_buffer *leaf; | |
270 | struct btrfs_extent_item *ei; | |
271 | struct btrfs_key key; | |
272 | u32 num_refs; | |
273 | int ret; | |
274 | ||
275 | path = btrfs_alloc_path(); | |
276 | if (!path) | |
277 | return -ENOMEM; | |
278 | ||
279 | key.objectid = bytenr; | |
280 | key.type = BTRFS_EXTENT_ITEM_KEY; | |
281 | key.offset = num_bytes; | |
282 | delayed_refs = &trans->transaction->delayed_refs; | |
283 | again: | |
284 | ret = btrfs_search_slot(trans, root->fs_info->extent_root, | |
285 | &key, path, 0, 0); | |
286 | if (ret < 0) | |
287 | goto out; | |
288 | ||
289 | if (ret == 0) { | |
290 | leaf = path->nodes[0]; | |
291 | ei = btrfs_item_ptr(leaf, path->slots[0], | |
292 | struct btrfs_extent_item); | |
293 | num_refs = btrfs_extent_refs(leaf, ei); | |
294 | } else { | |
295 | num_refs = 0; | |
296 | ret = 0; | |
297 | } | |
298 | ||
299 | spin_lock(&delayed_refs->lock); | |
c3e69d58 | 300 | ref = tree_search(&delayed_refs->root, bytenr, (u64)-1, NULL); |
56bec294 CM |
301 | if (ref) { |
302 | head = btrfs_delayed_node_to_head(ref); | |
303 | if (mutex_trylock(&head->mutex)) { | |
304 | num_refs += ref->ref_mod; | |
305 | mutex_unlock(&head->mutex); | |
306 | *refs = num_refs; | |
307 | goto out; | |
308 | } | |
309 | ||
310 | atomic_inc(&ref->refs); | |
311 | spin_unlock(&delayed_refs->lock); | |
312 | ||
313 | btrfs_release_path(root->fs_info->extent_root, path); | |
314 | ||
315 | mutex_lock(&head->mutex); | |
316 | mutex_unlock(&head->mutex); | |
317 | btrfs_put_delayed_ref(ref); | |
318 | goto again; | |
319 | } else { | |
320 | *refs = num_refs; | |
321 | } | |
322 | out: | |
323 | spin_unlock(&delayed_refs->lock); | |
324 | btrfs_free_path(path); | |
325 | return ret; | |
326 | } | |
327 | ||
328 | /* | |
329 | * helper function to update an extent delayed ref in the | |
330 | * rbtree. existing and update must both have the same | |
331 | * bytenr and parent | |
332 | * | |
333 | * This may free existing if the update cancels out whatever | |
334 | * operation it was doing. | |
335 | */ | |
336 | static noinline void | |
337 | update_existing_ref(struct btrfs_trans_handle *trans, | |
338 | struct btrfs_delayed_ref_root *delayed_refs, | |
339 | struct btrfs_delayed_ref_node *existing, | |
340 | struct btrfs_delayed_ref_node *update) | |
341 | { | |
342 | struct btrfs_delayed_ref *existing_ref; | |
343 | struct btrfs_delayed_ref *ref; | |
344 | ||
345 | existing_ref = btrfs_delayed_node_to_ref(existing); | |
346 | ref = btrfs_delayed_node_to_ref(update); | |
347 | ||
348 | if (ref->pin) | |
349 | existing_ref->pin = 1; | |
350 | ||
351 | if (ref->action != existing_ref->action) { | |
352 | /* | |
353 | * this is effectively undoing either an add or a | |
354 | * drop. We decrement the ref_mod, and if it goes | |
355 | * down to zero we just delete the entry without | |
356 | * every changing the extent allocation tree. | |
357 | */ | |
358 | existing->ref_mod--; | |
359 | if (existing->ref_mod == 0) { | |
360 | rb_erase(&existing->rb_node, | |
361 | &delayed_refs->root); | |
362 | existing->in_tree = 0; | |
363 | btrfs_put_delayed_ref(existing); | |
364 | delayed_refs->num_entries--; | |
365 | if (trans->delayed_ref_updates) | |
366 | trans->delayed_ref_updates--; | |
367 | } | |
368 | } else { | |
369 | if (existing_ref->action == BTRFS_ADD_DELAYED_REF) { | |
370 | /* if we're adding refs, make sure all the | |
371 | * details match up. The extent could | |
372 | * have been totally freed and reallocated | |
373 | * by a different owner before the delayed | |
374 | * ref entries were removed. | |
375 | */ | |
376 | existing_ref->owner_objectid = ref->owner_objectid; | |
377 | existing_ref->generation = ref->generation; | |
378 | existing_ref->root = ref->root; | |
379 | existing->num_bytes = update->num_bytes; | |
380 | } | |
381 | /* | |
382 | * the action on the existing ref matches | |
383 | * the action on the ref we're trying to add. | |
384 | * Bump the ref_mod by one so the backref that | |
385 | * is eventually added/removed has the correct | |
386 | * reference count | |
387 | */ | |
388 | existing->ref_mod += update->ref_mod; | |
389 | } | |
390 | } | |
391 | ||
392 | /* | |
393 | * helper function to update the accounting in the head ref | |
394 | * existing and update must have the same bytenr | |
395 | */ | |
396 | static noinline void | |
397 | update_existing_head_ref(struct btrfs_delayed_ref_node *existing, | |
398 | struct btrfs_delayed_ref_node *update) | |
399 | { | |
400 | struct btrfs_delayed_ref_head *existing_ref; | |
401 | struct btrfs_delayed_ref_head *ref; | |
402 | ||
403 | existing_ref = btrfs_delayed_node_to_head(existing); | |
404 | ref = btrfs_delayed_node_to_head(update); | |
405 | ||
406 | if (ref->must_insert_reserved) { | |
407 | /* if the extent was freed and then | |
408 | * reallocated before the delayed ref | |
409 | * entries were processed, we can end up | |
410 | * with an existing head ref without | |
411 | * the must_insert_reserved flag set. | |
412 | * Set it again here | |
413 | */ | |
414 | existing_ref->must_insert_reserved = ref->must_insert_reserved; | |
415 | ||
416 | /* | |
417 | * update the num_bytes so we make sure the accounting | |
418 | * is done correctly | |
419 | */ | |
420 | existing->num_bytes = update->num_bytes; | |
421 | ||
422 | } | |
423 | ||
424 | /* | |
425 | * update the reference mod on the head to reflect this new operation | |
426 | */ | |
427 | existing->ref_mod += update->ref_mod; | |
428 | } | |
429 | ||
430 | /* | |
431 | * helper function to actually insert a delayed ref into the rbtree. | |
432 | * this does all the dirty work in terms of maintaining the correct | |
433 | * overall modification count in the head node and properly dealing | |
434 | * with updating existing nodes as new modifications are queued. | |
435 | */ | |
436 | static noinline int __btrfs_add_delayed_ref(struct btrfs_trans_handle *trans, | |
437 | struct btrfs_delayed_ref_node *ref, | |
438 | u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root, | |
439 | u64 ref_generation, u64 owner_objectid, int action, | |
440 | int pin) | |
441 | { | |
442 | struct btrfs_delayed_ref_node *existing; | |
443 | struct btrfs_delayed_ref *full_ref; | |
c3e69d58 | 444 | struct btrfs_delayed_ref_head *head_ref = NULL; |
56bec294 CM |
445 | struct btrfs_delayed_ref_root *delayed_refs; |
446 | int count_mod = 1; | |
447 | int must_insert_reserved = 0; | |
448 | ||
449 | /* | |
450 | * the head node stores the sum of all the mods, so dropping a ref | |
451 | * should drop the sum in the head node by one. | |
452 | */ | |
1a81af4d CM |
453 | if (parent == (u64)-1) { |
454 | if (action == BTRFS_DROP_DELAYED_REF) | |
455 | count_mod = -1; | |
456 | else if (action == BTRFS_UPDATE_DELAYED_HEAD) | |
457 | count_mod = 0; | |
458 | } | |
56bec294 CM |
459 | |
460 | /* | |
461 | * BTRFS_ADD_DELAYED_EXTENT means that we need to update | |
462 | * the reserved accounting when the extent is finally added, or | |
463 | * if a later modification deletes the delayed ref without ever | |
464 | * inserting the extent into the extent allocation tree. | |
465 | * ref->must_insert_reserved is the flag used to record | |
466 | * that accounting mods are required. | |
467 | * | |
468 | * Once we record must_insert_reserved, switch the action to | |
469 | * BTRFS_ADD_DELAYED_REF because other special casing is not required. | |
470 | */ | |
471 | if (action == BTRFS_ADD_DELAYED_EXTENT) { | |
472 | must_insert_reserved = 1; | |
473 | action = BTRFS_ADD_DELAYED_REF; | |
474 | } else { | |
475 | must_insert_reserved = 0; | |
476 | } | |
477 | ||
478 | ||
479 | delayed_refs = &trans->transaction->delayed_refs; | |
480 | ||
481 | /* first set the basic ref node struct up */ | |
482 | atomic_set(&ref->refs, 1); | |
483 | ref->bytenr = bytenr; | |
484 | ref->parent = parent; | |
485 | ref->ref_mod = count_mod; | |
486 | ref->in_tree = 1; | |
487 | ref->num_bytes = num_bytes; | |
488 | ||
489 | if (btrfs_delayed_ref_is_head(ref)) { | |
490 | head_ref = btrfs_delayed_node_to_head(ref); | |
491 | head_ref->must_insert_reserved = must_insert_reserved; | |
c3e69d58 | 492 | INIT_LIST_HEAD(&head_ref->cluster); |
56bec294 CM |
493 | mutex_init(&head_ref->mutex); |
494 | } else { | |
495 | full_ref = btrfs_delayed_node_to_ref(ref); | |
496 | full_ref->root = ref_root; | |
497 | full_ref->generation = ref_generation; | |
498 | full_ref->owner_objectid = owner_objectid; | |
499 | full_ref->pin = pin; | |
500 | full_ref->action = action; | |
501 | } | |
502 | ||
503 | existing = tree_insert(&delayed_refs->root, bytenr, | |
504 | parent, &ref->rb_node); | |
505 | ||
506 | if (existing) { | |
507 | if (btrfs_delayed_ref_is_head(ref)) | |
508 | update_existing_head_ref(existing, ref); | |
509 | else | |
510 | update_existing_ref(trans, delayed_refs, existing, ref); | |
511 | ||
512 | /* | |
513 | * we've updated the existing ref, free the newly | |
514 | * allocated ref | |
515 | */ | |
516 | kfree(ref); | |
517 | } else { | |
c3e69d58 CM |
518 | if (btrfs_delayed_ref_is_head(ref)) { |
519 | delayed_refs->num_heads++; | |
520 | delayed_refs->num_heads_ready++; | |
521 | } | |
56bec294 CM |
522 | delayed_refs->num_entries++; |
523 | trans->delayed_ref_updates++; | |
524 | } | |
525 | return 0; | |
526 | } | |
527 | ||
528 | /* | |
529 | * add a delayed ref to the tree. This does all of the accounting required | |
530 | * to make sure the delayed ref is eventually processed before this | |
531 | * transaction commits. | |
532 | */ | |
533 | int btrfs_add_delayed_ref(struct btrfs_trans_handle *trans, | |
534 | u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root, | |
535 | u64 ref_generation, u64 owner_objectid, int action, | |
536 | int pin) | |
537 | { | |
538 | struct btrfs_delayed_ref *ref; | |
539 | struct btrfs_delayed_ref_head *head_ref; | |
540 | struct btrfs_delayed_ref_root *delayed_refs; | |
541 | int ret; | |
542 | ||
543 | ref = kmalloc(sizeof(*ref), GFP_NOFS); | |
544 | if (!ref) | |
545 | return -ENOMEM; | |
546 | ||
547 | /* | |
548 | * the parent = 0 case comes from cases where we don't actually | |
549 | * know the parent yet. It will get updated later via a add/drop | |
550 | * pair. | |
551 | */ | |
552 | if (parent == 0) | |
553 | parent = bytenr; | |
554 | ||
555 | head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS); | |
556 | if (!head_ref) { | |
557 | kfree(ref); | |
558 | return -ENOMEM; | |
559 | } | |
560 | delayed_refs = &trans->transaction->delayed_refs; | |
561 | spin_lock(&delayed_refs->lock); | |
562 | ||
563 | /* | |
564 | * insert both the head node and the new ref without dropping | |
565 | * the spin lock | |
566 | */ | |
567 | ret = __btrfs_add_delayed_ref(trans, &head_ref->node, bytenr, num_bytes, | |
568 | (u64)-1, 0, 0, 0, action, pin); | |
569 | BUG_ON(ret); | |
570 | ||
571 | ret = __btrfs_add_delayed_ref(trans, &ref->node, bytenr, num_bytes, | |
572 | parent, ref_root, ref_generation, | |
573 | owner_objectid, action, pin); | |
574 | BUG_ON(ret); | |
575 | spin_unlock(&delayed_refs->lock); | |
576 | return 0; | |
577 | } | |
578 | ||
1887be66 CM |
579 | /* |
580 | * this does a simple search for the head node for a given extent. | |
581 | * It must be called with the delayed ref spinlock held, and it returns | |
582 | * the head node if any where found, or NULL if not. | |
583 | */ | |
584 | struct btrfs_delayed_ref_head * | |
585 | btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr) | |
586 | { | |
587 | struct btrfs_delayed_ref_node *ref; | |
588 | struct btrfs_delayed_ref_root *delayed_refs; | |
589 | ||
590 | delayed_refs = &trans->transaction->delayed_refs; | |
c3e69d58 | 591 | ref = tree_search(&delayed_refs->root, bytenr, (u64)-1, NULL); |
1887be66 CM |
592 | if (ref) |
593 | return btrfs_delayed_node_to_head(ref); | |
594 | return NULL; | |
595 | } | |
596 | ||
56bec294 CM |
597 | /* |
598 | * add a delayed ref to the tree. This does all of the accounting required | |
599 | * to make sure the delayed ref is eventually processed before this | |
600 | * transaction commits. | |
601 | * | |
602 | * The main point of this call is to add and remove a backreference in a single | |
603 | * shot, taking the lock only once, and only searching for the head node once. | |
604 | * | |
605 | * It is the same as doing a ref add and delete in two separate calls. | |
606 | */ | |
607 | int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans, | |
608 | u64 bytenr, u64 num_bytes, u64 orig_parent, | |
609 | u64 parent, u64 orig_ref_root, u64 ref_root, | |
610 | u64 orig_ref_generation, u64 ref_generation, | |
611 | u64 owner_objectid, int pin) | |
612 | { | |
613 | struct btrfs_delayed_ref *ref; | |
614 | struct btrfs_delayed_ref *old_ref; | |
615 | struct btrfs_delayed_ref_head *head_ref; | |
616 | struct btrfs_delayed_ref_root *delayed_refs; | |
617 | int ret; | |
618 | ||
619 | ref = kmalloc(sizeof(*ref), GFP_NOFS); | |
620 | if (!ref) | |
621 | return -ENOMEM; | |
622 | ||
623 | old_ref = kmalloc(sizeof(*old_ref), GFP_NOFS); | |
624 | if (!old_ref) { | |
625 | kfree(ref); | |
626 | return -ENOMEM; | |
627 | } | |
628 | ||
629 | /* | |
630 | * the parent = 0 case comes from cases where we don't actually | |
631 | * know the parent yet. It will get updated later via a add/drop | |
632 | * pair. | |
633 | */ | |
634 | if (parent == 0) | |
635 | parent = bytenr; | |
636 | if (orig_parent == 0) | |
637 | orig_parent = bytenr; | |
638 | ||
639 | head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS); | |
640 | if (!head_ref) { | |
641 | kfree(ref); | |
642 | kfree(old_ref); | |
643 | return -ENOMEM; | |
644 | } | |
645 | delayed_refs = &trans->transaction->delayed_refs; | |
646 | spin_lock(&delayed_refs->lock); | |
647 | ||
648 | /* | |
649 | * insert both the head node and the new ref without dropping | |
650 | * the spin lock | |
651 | */ | |
652 | ret = __btrfs_add_delayed_ref(trans, &head_ref->node, bytenr, num_bytes, | |
653 | (u64)-1, 0, 0, 0, | |
1a81af4d | 654 | BTRFS_UPDATE_DELAYED_HEAD, 0); |
56bec294 CM |
655 | BUG_ON(ret); |
656 | ||
657 | ret = __btrfs_add_delayed_ref(trans, &ref->node, bytenr, num_bytes, | |
658 | parent, ref_root, ref_generation, | |
659 | owner_objectid, BTRFS_ADD_DELAYED_REF, 0); | |
660 | BUG_ON(ret); | |
661 | ||
662 | ret = __btrfs_add_delayed_ref(trans, &old_ref->node, bytenr, num_bytes, | |
663 | orig_parent, orig_ref_root, | |
664 | orig_ref_generation, owner_objectid, | |
665 | BTRFS_DROP_DELAYED_REF, pin); | |
666 | BUG_ON(ret); | |
667 | spin_unlock(&delayed_refs->lock); | |
668 | return 0; | |
669 | } |