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TOMOYO Linux Cross Reference
Linux/fs/btrfs/delayed-ref.c

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  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 "ctree.h"
 22 #include "delayed-ref.h"
 23 #include "transaction.h"
 24 
 25 /*
 26  * delayed back reference update tracking.  For subvolume trees
 27  * we queue up extent allocations and backref maintenance for
 28  * delayed processing.   This avoids deep call chains where we
 29  * add extents in the middle of btrfs_search_slot, and it allows
 30  * us to buffer up frequently modified backrefs in an rb tree instead
 31  * of hammering updates on the extent allocation tree.
 32  */
 33 
 34 /*
 35  * compare two delayed tree backrefs with same bytenr and type
 36  */
 37 static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref2,
 38                           struct btrfs_delayed_tree_ref *ref1)
 39 {
 40         if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) {
 41                 if (ref1->root < ref2->root)
 42                         return -1;
 43                 if (ref1->root > ref2->root)
 44                         return 1;
 45         } else {
 46                 if (ref1->parent < ref2->parent)
 47                         return -1;
 48                 if (ref1->parent > ref2->parent)
 49                         return 1;
 50         }
 51         return 0;
 52 }
 53 
 54 /*
 55  * compare two delayed data backrefs with same bytenr and type
 56  */
 57 static int comp_data_refs(struct btrfs_delayed_data_ref *ref2,
 58                           struct btrfs_delayed_data_ref *ref1)
 59 {
 60         if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
 61                 if (ref1->root < ref2->root)
 62                         return -1;
 63                 if (ref1->root > ref2->root)
 64                         return 1;
 65                 if (ref1->objectid < ref2->objectid)
 66                         return -1;
 67                 if (ref1->objectid > ref2->objectid)
 68                         return 1;
 69                 if (ref1->offset < ref2->offset)
 70                         return -1;
 71                 if (ref1->offset > ref2->offset)
 72                         return 1;
 73         } else {
 74                 if (ref1->parent < ref2->parent)
 75                         return -1;
 76                 if (ref1->parent > ref2->parent)
 77                         return 1;
 78         }
 79         return 0;
 80 }
 81 
 82 /*
 83  * entries in the rb tree are ordered by the byte number of the extent,
 84  * type of the delayed backrefs and content of delayed backrefs.
 85  */
 86 static int comp_entry(struct btrfs_delayed_ref_node *ref2,
 87                       struct btrfs_delayed_ref_node *ref1)
 88 {
 89         if (ref1->bytenr < ref2->bytenr)
 90                 return -1;
 91         if (ref1->bytenr > ref2->bytenr)
 92                 return 1;
 93         if (ref1->is_head && ref2->is_head)
 94                 return 0;
 95         if (ref2->is_head)
 96                 return -1;
 97         if (ref1->is_head)
 98                 return 1;
 99         if (ref1->type < ref2->type)
100                 return -1;
101         if (ref1->type > ref2->type)
102                 return 1;
103         if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
104             ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) {
105                 return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2),
106                                       btrfs_delayed_node_to_tree_ref(ref1));
107         } else if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY ||
108                    ref1->type == BTRFS_SHARED_DATA_REF_KEY) {
109                 return comp_data_refs(btrfs_delayed_node_to_data_ref(ref2),
110                                       btrfs_delayed_node_to_data_ref(ref1));
111         }
112         BUG();
113         return 0;
114 }
115 
116 /*
117  * insert a new ref into the rbtree.  This returns any existing refs
118  * for the same (bytenr,parent) tuple, or NULL if the new node was properly
119  * inserted.
120  */
121 static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root,
122                                                   struct rb_node *node)
123 {
124         struct rb_node **p = &root->rb_node;
125         struct rb_node *parent_node = NULL;
126         struct btrfs_delayed_ref_node *entry;
127         struct btrfs_delayed_ref_node *ins;
128         int cmp;
129 
130         ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
131         while (*p) {
132                 parent_node = *p;
133                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
134                                  rb_node);
135 
136                 cmp = comp_entry(entry, ins);
137                 if (cmp < 0)
138                         p = &(*p)->rb_left;
139                 else if (cmp > 0)
140                         p = &(*p)->rb_right;
141                 else
142                         return entry;
143         }
144 
145         rb_link_node(node, parent_node, p);
146         rb_insert_color(node, root);
147         return NULL;
148 }
149 
150 /*
151  * find an head entry based on bytenr. This returns the delayed ref
152  * head if it was able to find one, or NULL if nothing was in that spot
153  */
154 static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root,
155                                   u64 bytenr,
156                                   struct btrfs_delayed_ref_node **last)
157 {
158         struct rb_node *n = root->rb_node;
159         struct btrfs_delayed_ref_node *entry;
160         int cmp;
161 
162         while (n) {
163                 entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
164                 WARN_ON(!entry->in_tree);
165                 if (last)
166                         *last = entry;
167 
168                 if (bytenr < entry->bytenr)
169                         cmp = -1;
170                 else if (bytenr > entry->bytenr)
171                         cmp = 1;
172                 else if (!btrfs_delayed_ref_is_head(entry))
173                         cmp = 1;
174                 else
175                         cmp = 0;
176 
177                 if (cmp < 0)
178                         n = n->rb_left;
179                 else if (cmp > 0)
180                         n = n->rb_right;
181                 else
182                         return entry;
183         }
184         return NULL;
185 }
186 
187 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
188                            struct btrfs_delayed_ref_head *head)
189 {
190         struct btrfs_delayed_ref_root *delayed_refs;
191 
192         delayed_refs = &trans->transaction->delayed_refs;
193         assert_spin_locked(&delayed_refs->lock);
194         if (mutex_trylock(&head->mutex))
195                 return 0;
196 
197         atomic_inc(&head->node.refs);
198         spin_unlock(&delayed_refs->lock);
199 
200         mutex_lock(&head->mutex);
201         spin_lock(&delayed_refs->lock);
202         if (!head->node.in_tree) {
203                 mutex_unlock(&head->mutex);
204                 btrfs_put_delayed_ref(&head->node);
205                 return -EAGAIN;
206         }
207         btrfs_put_delayed_ref(&head->node);
208         return 0;
209 }
210 
211 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
212                            struct list_head *cluster, u64 start)
213 {
214         int count = 0;
215         struct btrfs_delayed_ref_root *delayed_refs;
216         struct rb_node *node;
217         struct btrfs_delayed_ref_node *ref;
218         struct btrfs_delayed_ref_head *head;
219 
220         delayed_refs = &trans->transaction->delayed_refs;
221         if (start == 0) {
222                 node = rb_first(&delayed_refs->root);
223         } else {
224                 ref = NULL;
225                 find_ref_head(&delayed_refs->root, start, &ref);
226                 if (ref) {
227                         struct btrfs_delayed_ref_node *tmp;
228 
229                         node = rb_prev(&ref->rb_node);
230                         while (node) {
231                                 tmp = rb_entry(node,
232                                                struct btrfs_delayed_ref_node,
233                                                rb_node);
234                                 if (tmp->bytenr < start)
235                                         break;
236                                 ref = tmp;
237                                 node = rb_prev(&ref->rb_node);
238                         }
239                         node = &ref->rb_node;
240                 } else
241                         node = rb_first(&delayed_refs->root);
242         }
243 again:
244         while (node && count < 32) {
245                 ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
246                 if (btrfs_delayed_ref_is_head(ref)) {
247                         head = btrfs_delayed_node_to_head(ref);
248                         if (list_empty(&head->cluster)) {
249                                 list_add_tail(&head->cluster, cluster);
250                                 delayed_refs->run_delayed_start =
251                                         head->node.bytenr;
252                                 count++;
253 
254                                 WARN_ON(delayed_refs->num_heads_ready == 0);
255                                 delayed_refs->num_heads_ready--;
256                         } else if (count) {
257                                 /* the goal of the clustering is to find extents
258                                  * that are likely to end up in the same extent
259                                  * leaf on disk.  So, we don't want them spread
260                                  * all over the tree.  Stop now if we've hit
261                                  * a head that was already in use
262                                  */
263                                 break;
264                         }
265                 }
266                 node = rb_next(node);
267         }
268         if (count) {
269                 return 0;
270         } else if (start) {
271                 /*
272                  * we've gone to the end of the rbtree without finding any
273                  * clusters.  start from the beginning and try again
274                  */
275                 start = 0;
276                 node = rb_first(&delayed_refs->root);
277                 goto again;
278         }
279         return 1;
280 }
281 
282 /*
283  * This checks to see if there are any delayed refs in the
284  * btree for a given bytenr.  It returns one if it finds any
285  * and zero otherwise.
286  *
287  * If it only finds a head node, it returns 0.
288  *
289  * The idea is to use this when deciding if you can safely delete an
290  * extent from the extent allocation tree.  There may be a pending
291  * ref in the rbtree that adds or removes references, so as long as this
292  * returns one you need to leave the BTRFS_EXTENT_ITEM in the extent
293  * allocation tree.
294  */
295 int btrfs_delayed_ref_pending(struct btrfs_trans_handle *trans, u64 bytenr)
296 {
297         struct btrfs_delayed_ref_node *ref;
298         struct btrfs_delayed_ref_root *delayed_refs;
299         struct rb_node *prev_node;
300         int ret = 0;
301 
302         delayed_refs = &trans->transaction->delayed_refs;
303         spin_lock(&delayed_refs->lock);
304 
305         ref = find_ref_head(&delayed_refs->root, bytenr, NULL);
306         if (ref) {
307                 prev_node = rb_prev(&ref->rb_node);
308                 if (!prev_node)
309                         goto out;
310                 ref = rb_entry(prev_node, struct btrfs_delayed_ref_node,
311                                rb_node);
312                 if (ref->bytenr == bytenr)
313                         ret = 1;
314         }
315 out:
316         spin_unlock(&delayed_refs->lock);
317         return ret;
318 }
319 
320 /*
321  * helper function to lookup reference count and flags of extent.
322  *
323  * the head node for delayed ref is used to store the sum of all the
324  * reference count modifications queued up in the rbtree. the head
325  * node may also store the extent flags to set. This way you can check
326  * to see what the reference count and extent flags would be if all of
327  * the delayed refs are not processed.
328  */
329 int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
330                              struct btrfs_root *root, u64 bytenr,
331                              u64 num_bytes, u64 *refs, u64 *flags)
332 {
333         struct btrfs_delayed_ref_node *ref;
334         struct btrfs_delayed_ref_head *head;
335         struct btrfs_delayed_ref_root *delayed_refs;
336         struct btrfs_path *path;
337         struct btrfs_extent_item *ei;
338         struct extent_buffer *leaf;
339         struct btrfs_key key;
340         u32 item_size;
341         u64 num_refs;
342         u64 extent_flags;
343         int ret;
344 
345         path = btrfs_alloc_path();
346         if (!path)
347                 return -ENOMEM;
348 
349         key.objectid = bytenr;
350         key.type = BTRFS_EXTENT_ITEM_KEY;
351         key.offset = num_bytes;
352         delayed_refs = &trans->transaction->delayed_refs;
353 again:
354         ret = btrfs_search_slot(trans, root->fs_info->extent_root,
355                                 &key, path, 0, 0);
356         if (ret < 0)
357                 goto out;
358 
359         if (ret == 0) {
360                 leaf = path->nodes[0];
361                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
362                 if (item_size >= sizeof(*ei)) {
363                         ei = btrfs_item_ptr(leaf, path->slots[0],
364                                             struct btrfs_extent_item);
365                         num_refs = btrfs_extent_refs(leaf, ei);
366                         extent_flags = btrfs_extent_flags(leaf, ei);
367                 } else {
368 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
369                         struct btrfs_extent_item_v0 *ei0;
370                         BUG_ON(item_size != sizeof(*ei0));
371                         ei0 = btrfs_item_ptr(leaf, path->slots[0],
372                                              struct btrfs_extent_item_v0);
373                         num_refs = btrfs_extent_refs_v0(leaf, ei0);
374                         /* FIXME: this isn't correct for data */
375                         extent_flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
376 #else
377                         BUG();
378 #endif
379                 }
380                 BUG_ON(num_refs == 0);
381         } else {
382                 num_refs = 0;
383                 extent_flags = 0;
384                 ret = 0;
385         }
386 
387         spin_lock(&delayed_refs->lock);
388         ref = find_ref_head(&delayed_refs->root, bytenr, NULL);
389         if (ref) {
390                 head = btrfs_delayed_node_to_head(ref);
391                 if (!mutex_trylock(&head->mutex)) {
392                         atomic_inc(&ref->refs);
393                         spin_unlock(&delayed_refs->lock);
394 
395                         btrfs_release_path(root->fs_info->extent_root, path);
396 
397                         mutex_lock(&head->mutex);
398                         mutex_unlock(&head->mutex);
399                         btrfs_put_delayed_ref(ref);
400                         goto again;
401                 }
402                 if (head->extent_op && head->extent_op->update_flags)
403                         extent_flags |= head->extent_op->flags_to_set;
404                 else
405                         BUG_ON(num_refs == 0);
406 
407                 num_refs += ref->ref_mod;
408                 mutex_unlock(&head->mutex);
409         }
410         WARN_ON(num_refs == 0);
411         if (refs)
412                 *refs = num_refs;
413         if (flags)
414                 *flags = extent_flags;
415 out:
416         spin_unlock(&delayed_refs->lock);
417         btrfs_free_path(path);
418         return ret;
419 }
420 
421 /*
422  * helper function to update an extent delayed ref in the
423  * rbtree.  existing and update must both have the same
424  * bytenr and parent
425  *
426  * This may free existing if the update cancels out whatever
427  * operation it was doing.
428  */
429 static noinline void
430 update_existing_ref(struct btrfs_trans_handle *trans,
431                     struct btrfs_delayed_ref_root *delayed_refs,
432                     struct btrfs_delayed_ref_node *existing,
433                     struct btrfs_delayed_ref_node *update)
434 {
435         if (update->action != existing->action) {
436                 /*
437                  * this is effectively undoing either an add or a
438                  * drop.  We decrement the ref_mod, and if it goes
439                  * down to zero we just delete the entry without
440                  * every changing the extent allocation tree.
441                  */
442                 existing->ref_mod--;
443                 if (existing->ref_mod == 0) {
444                         rb_erase(&existing->rb_node,
445                                  &delayed_refs->root);
446                         existing->in_tree = 0;
447                         btrfs_put_delayed_ref(existing);
448                         delayed_refs->num_entries--;
449                         if (trans->delayed_ref_updates)
450                                 trans->delayed_ref_updates--;
451                 } else {
452                         WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
453                                 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
454                 }
455         } else {
456                 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
457                         existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
458                 /*
459                  * the action on the existing ref matches
460                  * the action on the ref we're trying to add.
461                  * Bump the ref_mod by one so the backref that
462                  * is eventually added/removed has the correct
463                  * reference count
464                  */
465                 existing->ref_mod += update->ref_mod;
466         }
467 }
468 
469 /*
470  * helper function to update the accounting in the head ref
471  * existing and update must have the same bytenr
472  */
473 static noinline void
474 update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
475                          struct btrfs_delayed_ref_node *update)
476 {
477         struct btrfs_delayed_ref_head *existing_ref;
478         struct btrfs_delayed_ref_head *ref;
479 
480         existing_ref = btrfs_delayed_node_to_head(existing);
481         ref = btrfs_delayed_node_to_head(update);
482         BUG_ON(existing_ref->is_data != ref->is_data);
483 
484         if (ref->must_insert_reserved) {
485                 /* if the extent was freed and then
486                  * reallocated before the delayed ref
487                  * entries were processed, we can end up
488                  * with an existing head ref without
489                  * the must_insert_reserved flag set.
490                  * Set it again here
491                  */
492                 existing_ref->must_insert_reserved = ref->must_insert_reserved;
493 
494                 /*
495                  * update the num_bytes so we make sure the accounting
496                  * is done correctly
497                  */
498                 existing->num_bytes = update->num_bytes;
499 
500         }
501 
502         if (ref->extent_op) {
503                 if (!existing_ref->extent_op) {
504                         existing_ref->extent_op = ref->extent_op;
505                 } else {
506                         if (ref->extent_op->update_key) {
507                                 memcpy(&existing_ref->extent_op->key,
508                                        &ref->extent_op->key,
509                                        sizeof(ref->extent_op->key));
510                                 existing_ref->extent_op->update_key = 1;
511                         }
512                         if (ref->extent_op->update_flags) {
513                                 existing_ref->extent_op->flags_to_set |=
514                                         ref->extent_op->flags_to_set;
515                                 existing_ref->extent_op->update_flags = 1;
516                         }
517                         kfree(ref->extent_op);
518                 }
519         }
520         /*
521          * update the reference mod on the head to reflect this new operation
522          */
523         existing->ref_mod += update->ref_mod;
524 }
525 
526 /*
527  * helper function to actually insert a head node into the rbtree.
528  * this does all the dirty work in terms of maintaining the correct
529  * overall modification count.
530  */
531 static noinline int add_delayed_ref_head(struct btrfs_trans_handle *trans,
532                                         struct btrfs_delayed_ref_node *ref,
533                                         u64 bytenr, u64 num_bytes,
534                                         int action, int is_data)
535 {
536         struct btrfs_delayed_ref_node *existing;
537         struct btrfs_delayed_ref_head *head_ref = NULL;
538         struct btrfs_delayed_ref_root *delayed_refs;
539         int count_mod = 1;
540         int must_insert_reserved = 0;
541 
542         /*
543          * the head node stores the sum of all the mods, so dropping a ref
544          * should drop the sum in the head node by one.
545          */
546         if (action == BTRFS_UPDATE_DELAYED_HEAD)
547                 count_mod = 0;
548         else if (action == BTRFS_DROP_DELAYED_REF)
549                 count_mod = -1;
550 
551         /*
552          * BTRFS_ADD_DELAYED_EXTENT means that we need to update
553          * the reserved accounting when the extent is finally added, or
554          * if a later modification deletes the delayed ref without ever
555          * inserting the extent into the extent allocation tree.
556          * ref->must_insert_reserved is the flag used to record
557          * that accounting mods are required.
558          *
559          * Once we record must_insert_reserved, switch the action to
560          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
561          */
562         if (action == BTRFS_ADD_DELAYED_EXTENT)
563                 must_insert_reserved = 1;
564         else
565                 must_insert_reserved = 0;
566 
567         delayed_refs = &trans->transaction->delayed_refs;
568 
569         /* first set the basic ref node struct up */
570         atomic_set(&ref->refs, 1);
571         ref->bytenr = bytenr;
572         ref->num_bytes = num_bytes;
573         ref->ref_mod = count_mod;
574         ref->type  = 0;
575         ref->action  = 0;
576         ref->is_head = 1;
577         ref->in_tree = 1;
578 
579         head_ref = btrfs_delayed_node_to_head(ref);
580         head_ref->must_insert_reserved = must_insert_reserved;
581         head_ref->is_data = is_data;
582 
583         INIT_LIST_HEAD(&head_ref->cluster);
584         mutex_init(&head_ref->mutex);
585 
586         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
587 
588         if (existing) {
589                 update_existing_head_ref(existing, ref);
590                 /*
591                  * we've updated the existing ref, free the newly
592                  * allocated ref
593                  */
594                 kfree(ref);
595         } else {
596                 delayed_refs->num_heads++;
597                 delayed_refs->num_heads_ready++;
598                 delayed_refs->num_entries++;
599                 trans->delayed_ref_updates++;
600         }
601         return 0;
602 }
603 
604 /*
605  * helper to insert a delayed tree ref into the rbtree.
606  */
607 static noinline int add_delayed_tree_ref(struct btrfs_trans_handle *trans,
608                                          struct btrfs_delayed_ref_node *ref,
609                                          u64 bytenr, u64 num_bytes, u64 parent,
610                                          u64 ref_root, int level, int action)
611 {
612         struct btrfs_delayed_ref_node *existing;
613         struct btrfs_delayed_tree_ref *full_ref;
614         struct btrfs_delayed_ref_root *delayed_refs;
615 
616         if (action == BTRFS_ADD_DELAYED_EXTENT)
617                 action = BTRFS_ADD_DELAYED_REF;
618 
619         delayed_refs = &trans->transaction->delayed_refs;
620 
621         /* first set the basic ref node struct up */
622         atomic_set(&ref->refs, 1);
623         ref->bytenr = bytenr;
624         ref->num_bytes = num_bytes;
625         ref->ref_mod = 1;
626         ref->action = action;
627         ref->is_head = 0;
628         ref->in_tree = 1;
629 
630         full_ref = btrfs_delayed_node_to_tree_ref(ref);
631         if (parent) {
632                 full_ref->parent = parent;
633                 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
634         } else {
635                 full_ref->root = ref_root;
636                 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
637         }
638         full_ref->level = level;
639 
640         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
641 
642         if (existing) {
643                 update_existing_ref(trans, delayed_refs, existing, ref);
644                 /*
645                  * we've updated the existing ref, free the newly
646                  * allocated ref
647                  */
648                 kfree(ref);
649         } else {
650                 delayed_refs->num_entries++;
651                 trans->delayed_ref_updates++;
652         }
653         return 0;
654 }
655 
656 /*
657  * helper to insert a delayed data ref into the rbtree.
658  */
659 static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans,
660                                          struct btrfs_delayed_ref_node *ref,
661                                          u64 bytenr, u64 num_bytes, u64 parent,
662                                          u64 ref_root, u64 owner, u64 offset,
663                                          int action)
664 {
665         struct btrfs_delayed_ref_node *existing;
666         struct btrfs_delayed_data_ref *full_ref;
667         struct btrfs_delayed_ref_root *delayed_refs;
668 
669         if (action == BTRFS_ADD_DELAYED_EXTENT)
670                 action = BTRFS_ADD_DELAYED_REF;
671 
672         delayed_refs = &trans->transaction->delayed_refs;
673 
674         /* first set the basic ref node struct up */
675         atomic_set(&ref->refs, 1);
676         ref->bytenr = bytenr;
677         ref->num_bytes = num_bytes;
678         ref->ref_mod = 1;
679         ref->action = action;
680         ref->is_head = 0;
681         ref->in_tree = 1;
682 
683         full_ref = btrfs_delayed_node_to_data_ref(ref);
684         if (parent) {
685                 full_ref->parent = parent;
686                 ref->type = BTRFS_SHARED_DATA_REF_KEY;
687         } else {
688                 full_ref->root = ref_root;
689                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
690         }
691         full_ref->objectid = owner;
692         full_ref->offset = offset;
693 
694         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
695 
696         if (existing) {
697                 update_existing_ref(trans, delayed_refs, existing, ref);
698                 /*
699                  * we've updated the existing ref, free the newly
700                  * allocated ref
701                  */
702                 kfree(ref);
703         } else {
704                 delayed_refs->num_entries++;
705                 trans->delayed_ref_updates++;
706         }
707         return 0;
708 }
709 
710 /*
711  * add a delayed tree ref.  This does all of the accounting required
712  * to make sure the delayed ref is eventually processed before this
713  * transaction commits.
714  */
715 int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
716                                u64 bytenr, u64 num_bytes, u64 parent,
717                                u64 ref_root,  int level, int action,
718                                struct btrfs_delayed_extent_op *extent_op)
719 {
720         struct btrfs_delayed_tree_ref *ref;
721         struct btrfs_delayed_ref_head *head_ref;
722         struct btrfs_delayed_ref_root *delayed_refs;
723         int ret;
724 
725         BUG_ON(extent_op && extent_op->is_data);
726         ref = kmalloc(sizeof(*ref), GFP_NOFS);
727         if (!ref)
728                 return -ENOMEM;
729 
730         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
731         if (!head_ref) {
732                 kfree(ref);
733                 return -ENOMEM;
734         }
735 
736         head_ref->extent_op = extent_op;
737 
738         delayed_refs = &trans->transaction->delayed_refs;
739         spin_lock(&delayed_refs->lock);
740 
741         /*
742          * insert both the head node and the new ref without dropping
743          * the spin lock
744          */
745         ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
746                                    action, 0);
747         BUG_ON(ret);
748 
749         ret = add_delayed_tree_ref(trans, &ref->node, bytenr, num_bytes,
750                                    parent, ref_root, level, action);
751         BUG_ON(ret);
752         spin_unlock(&delayed_refs->lock);
753         return 0;
754 }
755 
756 /*
757  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
758  */
759 int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
760                                u64 bytenr, u64 num_bytes,
761                                u64 parent, u64 ref_root,
762                                u64 owner, u64 offset, int action,
763                                struct btrfs_delayed_extent_op *extent_op)
764 {
765         struct btrfs_delayed_data_ref *ref;
766         struct btrfs_delayed_ref_head *head_ref;
767         struct btrfs_delayed_ref_root *delayed_refs;
768         int ret;
769 
770         BUG_ON(extent_op && !extent_op->is_data);
771         ref = kmalloc(sizeof(*ref), GFP_NOFS);
772         if (!ref)
773                 return -ENOMEM;
774 
775         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
776         if (!head_ref) {
777                 kfree(ref);
778                 return -ENOMEM;
779         }
780 
781         head_ref->extent_op = extent_op;
782 
783         delayed_refs = &trans->transaction->delayed_refs;
784         spin_lock(&delayed_refs->lock);
785 
786         /*
787          * insert both the head node and the new ref without dropping
788          * the spin lock
789          */
790         ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
791                                    action, 1);
792         BUG_ON(ret);
793 
794         ret = add_delayed_data_ref(trans, &ref->node, bytenr, num_bytes,
795                                    parent, ref_root, owner, offset, action);
796         BUG_ON(ret);
797         spin_unlock(&delayed_refs->lock);
798         return 0;
799 }
800 
801 int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
802                                 u64 bytenr, u64 num_bytes,
803                                 struct btrfs_delayed_extent_op *extent_op)
804 {
805         struct btrfs_delayed_ref_head *head_ref;
806         struct btrfs_delayed_ref_root *delayed_refs;
807         int ret;
808 
809         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
810         if (!head_ref)
811                 return -ENOMEM;
812 
813         head_ref->extent_op = extent_op;
814 
815         delayed_refs = &trans->transaction->delayed_refs;
816         spin_lock(&delayed_refs->lock);
817 
818         ret = add_delayed_ref_head(trans, &head_ref->node, bytenr,
819                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
820                                    extent_op->is_data);
821         BUG_ON(ret);
822 
823         spin_unlock(&delayed_refs->lock);
824         return 0;
825 }
826 
827 /*
828  * this does a simple search for the head node for a given extent.
829  * It must be called with the delayed ref spinlock held, and it returns
830  * the head node if any where found, or NULL if not.
831  */
832 struct btrfs_delayed_ref_head *
833 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
834 {
835         struct btrfs_delayed_ref_node *ref;
836         struct btrfs_delayed_ref_root *delayed_refs;
837 
838         delayed_refs = &trans->transaction->delayed_refs;
839         ref = find_ref_head(&delayed_refs->root, bytenr, NULL);
840         if (ref)
841                 return btrfs_delayed_node_to_head(ref);
842         return NULL;
843 }
844 
845 /*
846  * add a delayed ref to the tree.  This does all of the accounting required
847  * to make sure the delayed ref is eventually processed before this
848  * transaction commits.
849  *
850  * The main point of this call is to add and remove a backreference in a single
851  * shot, taking the lock only once, and only searching for the head node once.
852  *
853  * It is the same as doing a ref add and delete in two separate calls.
854  */
855 #if 0
856 int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
857                           u64 bytenr, u64 num_bytes, u64 orig_parent,
858                           u64 parent, u64 orig_ref_root, u64 ref_root,
859                           u64 orig_ref_generation, u64 ref_generation,
860                           u64 owner_objectid, int pin)
861 {
862         struct btrfs_delayed_ref *ref;
863         struct btrfs_delayed_ref *old_ref;
864         struct btrfs_delayed_ref_head *head_ref;
865         struct btrfs_delayed_ref_root *delayed_refs;
866         int ret;
867 
868         ref = kmalloc(sizeof(*ref), GFP_NOFS);
869         if (!ref)
870                 return -ENOMEM;
871 
872         old_ref = kmalloc(sizeof(*old_ref), GFP_NOFS);
873         if (!old_ref) {
874                 kfree(ref);
875                 return -ENOMEM;
876         }
877 
878         /*
879          * the parent = 0 case comes from cases where we don't actually
880          * know the parent yet.  It will get updated later via a add/drop
881          * pair.
882          */
883         if (parent == 0)
884                 parent = bytenr;
885         if (orig_parent == 0)
886                 orig_parent = bytenr;
887 
888         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
889         if (!head_ref) {
890                 kfree(ref);
891                 kfree(old_ref);
892                 return -ENOMEM;
893         }
894         delayed_refs = &trans->transaction->delayed_refs;
895         spin_lock(&delayed_refs->lock);
896 
897         /*
898          * insert both the head node and the new ref without dropping
899          * the spin lock
900          */
901         ret = __btrfs_add_delayed_ref(trans, &head_ref->node, bytenr, num_bytes,
902                                       (u64)-1, 0, 0, 0,
903                                       BTRFS_UPDATE_DELAYED_HEAD, 0);
904         BUG_ON(ret);
905 
906         ret = __btrfs_add_delayed_ref(trans, &ref->node, bytenr, num_bytes,
907                                       parent, ref_root, ref_generation,
908                                       owner_objectid, BTRFS_ADD_DELAYED_REF, 0);
909         BUG_ON(ret);
910 
911         ret = __btrfs_add_delayed_ref(trans, &old_ref->node, bytenr, num_bytes,
912                                       orig_parent, orig_ref_root,
913                                       orig_ref_generation, owner_objectid,
914                                       BTRFS_DROP_DELAYED_REF, pin);
915         BUG_ON(ret);
916         spin_unlock(&delayed_refs->lock);
917         return 0;
918 }
919 #endif
920 

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