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_fs_info *fs_info,
 237                             struct btrfs_delayed_ref_root *delayed_refs,
 238                             u64 seq)
 239 {
 240         struct seq_list *elem;
 241         int ret = 0;
 242
 243         spin_lock(&fs_info->tree_mod_seq_lock);
 244         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 245                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 246                                         struct seq_list, list);
 247                 if (seq >= elem->seq) {
 248                         pr_debug("holding back delayed_ref %llu, lowest is "
 249                                  "%llu (%p)\n", seq, elem->seq, delayed_refs);
 250                         ret = 1;
 251                 }
 252         }
 253
 254         spin_unlock(&fs_info->tree_mod_seq_lock);
 255         return ret;
 256 }
 257
 258 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
 259                            struct list_head *cluster, u64 start)
 260 {
 261         int count = 0;
 262         struct btrfs_delayed_ref_root *delayed_refs;
 263         struct rb_node *node;
 264         struct btrfs_delayed_ref_node *ref;
 265         struct btrfs_delayed_ref_head *head;
 266
 267         delayed_refs = &trans->transaction->delayed_refs;
 268         if (start == 0) {
 269                 node = rb_first(&delayed_refs->root);
 270         } else {
 271                 ref = NULL;
 272                 find_ref_head(&delayed_refs->root, start + 1, &ref, 1);
 273                 if (ref) {
 274                         node = &ref->rb_node;
 275                 } else
 276                         node = rb_first(&delayed_refs->root);
 277         }
 278 again:
 279         while (node && count < 32) {
 280                 ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 281                 if (btrfs_delayed_ref_is_head(ref)) {
 282                         head = btrfs_delayed_node_to_head(ref);
 283                         if (list_empty(&head->cluster)) {
 284                                 list_add_tail(&head->cluster, cluster);
 285                                 delayed_refs->run_delayed_start =
 286                                         head->node.bytenr;
 287                                 count++;
 288
 289                                 WARN_ON(delayed_refs->num_heads_ready == 0);
 290                                 delayed_refs->num_heads_ready--;
 291                         } else if (count) {
 292                                 /* the goal of the clustering is to find extents
 293                                  * that are likely to end up in the same extent
 294                                  * leaf on disk.  So, we don't want them spread
 295                                  * all over the tree.  Stop now if we've hit
 296                                  * a head that was already in use
 297                                  */
 298                                 break;
 299                         }
 300                 }
 301                 node = rb_next(node);
 302         }
 303         if (count) {
 304                 return 0;
 305         } else if (start) {
 306                 /*
 307                  * we've gone to the end of the rbtree without finding any
 308                  * clusters.  start from the beginning and try again
 309                  */
 310                 start = 0;
 311                 node = rb_first(&delayed_refs->root);
 312                 goto again;
 313         }
 314         return 1;
 315 }
 316
 317 /*
 318  * helper function to update an extent delayed ref in the
 319  * rbtree.  existing and update must both have the same
 320  * bytenr and parent
 321  *
 322  * This may free existing if the update cancels out whatever
 323  * operation it was doing.
 324  */
 325 static noinline void
 326 update_existing_ref(struct btrfs_trans_handle *trans,
 327                     struct btrfs_delayed_ref_root *delayed_refs,
 328                     struct btrfs_delayed_ref_node *existing,
 329                     struct btrfs_delayed_ref_node *update)
 330 {
 331         if (update->action != existing->action) {
 332                 /*
 333                  * this is effectively undoing either an add or a
 334                  * drop.  We decrement the ref_mod, and if it goes
 335                  * down to zero we just delete the entry without
 336                  * every changing the extent allocation tree.
 337                  */
 338                 existing->ref_mod--;
 339                 if (existing->ref_mod == 0) {
 340                         rb_erase(&existing->rb_node,
 341                                  &delayed_refs->root);
 342                         existing->in_tree = 0;
 343                         btrfs_put_delayed_ref(existing);
 344                         delayed_refs->num_entries--;
 345                         if (trans->delayed_ref_updates)
 346                                 trans->delayed_ref_updates--;
 347                 } else {
 348                         WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 349                                 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 350                 }
 351         } else {
 352                 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 353                         existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 354                 /*
 355                  * the action on the existing ref matches
 356                  * the action on the ref we're trying to add.
 357                  * Bump the ref_mod by one so the backref that
 358                  * is eventually added/removed has the correct
 359                  * reference count
 360                  */
 361                 existing->ref_mod += update->ref_mod;
 362         }
 363 }
 364
 365 /*
 366  * helper function to update the accounting in the head ref
 367  * existing and update must have the same bytenr
 368  */
 369 static noinline void
 370 update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
 371                          struct btrfs_delayed_ref_node *update)
 372 {
 373         struct btrfs_delayed_ref_head *existing_ref;
 374         struct btrfs_delayed_ref_head *ref;
 375
 376         existing_ref = btrfs_delayed_node_to_head(existing);
 377         ref = btrfs_delayed_node_to_head(update);
 378         BUG_ON(existing_ref->is_data != ref->is_data);
 379
 380         if (ref->must_insert_reserved) {
 381                 /* if the extent was freed and then
 382                  * reallocated before the delayed ref
 383                  * entries were processed, we can end up
 384                  * with an existing head ref without
 385                  * the must_insert_reserved flag set.
 386                  * Set it again here
 387                  */
 388                 existing_ref->must_insert_reserved = ref->must_insert_reserved;
 389
 390                 /*
 391                  * update the num_bytes so we make sure the accounting
 392                  * is done correctly
 393                  */
 394                 existing->num_bytes = update->num_bytes;
 395
 396         }
 397
 398         if (ref->extent_op) {
 399                 if (!existing_ref->extent_op) {
 400                         existing_ref->extent_op = ref->extent_op;
 401                 } else {
 402                         if (ref->extent_op->update_key) {
 403                                 memcpy(&existing_ref->extent_op->key,
 404                                        &ref->extent_op->key,
 405                                        sizeof(ref->extent_op->key));
 406                                 existing_ref->extent_op->update_key = 1;
 407                         }
 408                         if (ref->extent_op->update_flags) {
 409                                 existing_ref->extent_op->flags_to_set |=
 410                                         ref->extent_op->flags_to_set;
 411                                 existing_ref->extent_op->update_flags = 1;
 412                         }
 413                         kfree(ref->extent_op);
 414                 }
 415         }
 416         /*
 417          * update the reference mod on the head to reflect this new operation
 418          */
 419         existing->ref_mod += update->ref_mod;
 420 }
 421
 422 /*
 423  * helper function to actually insert a head node into the rbtree.
 424  * this does all the dirty work in terms of maintaining the correct
 425  * overall modification count.
 426  */
 427 static noinline void add_delayed_ref_head(struct btrfs_fs_info *fs_info,
 428                                         struct btrfs_trans_handle *trans,
 429                                         struct btrfs_delayed_ref_node *ref,
 430                                         u64 bytenr, u64 num_bytes,
 431                                         int action, int is_data)
 432 {
 433         struct btrfs_delayed_ref_node *existing;
 434         struct btrfs_delayed_ref_head *head_ref = NULL;
 435         struct btrfs_delayed_ref_root *delayed_refs;
 436         int count_mod = 1;
 437         int must_insert_reserved = 0;
 438
 439         /*
 440          * the head node stores the sum of all the mods, so dropping a ref
 441          * should drop the sum in the head node by one.
 442          */
 443         if (action == BTRFS_UPDATE_DELAYED_HEAD)
 444                 count_mod = 0;
 445         else if (action == BTRFS_DROP_DELAYED_REF)
 446                 count_mod = -1;
 447
 448         /*
 449          * BTRFS_ADD_DELAYED_EXTENT means that we need to update
 450          * the reserved accounting when the extent is finally added, or
 451          * if a later modification deletes the delayed ref without ever
 452          * inserting the extent into the extent allocation tree.
 453          * ref->must_insert_reserved is the flag used to record
 454          * that accounting mods are required.
 455          *
 456          * Once we record must_insert_reserved, switch the action to
 457          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
 458          */
 459         if (action == BTRFS_ADD_DELAYED_EXTENT)
 460                 must_insert_reserved = 1;
 461         else
 462                 must_insert_reserved = 0;
 463
 464         delayed_refs = &trans->transaction->delayed_refs;
 465
 466         /* first set the basic ref node struct up */
 467         atomic_set(&ref->refs, 1);
 468         ref->bytenr = bytenr;
 469         ref->num_bytes = num_bytes;
 470         ref->ref_mod = count_mod;
 471         ref->type  = 0;
 472         ref->action  = 0;
 473         ref->is_head = 1;
 474         ref->in_tree = 1;
 475         ref->seq = 0;
 476
 477         head_ref = btrfs_delayed_node_to_head(ref);
 478         head_ref->must_insert_reserved = must_insert_reserved;
 479         head_ref->is_data = is_data;
 480
 481         INIT_LIST_HEAD(&head_ref->cluster);
 482         mutex_init(&head_ref->mutex);
 483
 484         trace_btrfs_delayed_ref_head(ref, head_ref, action);
 485
 486         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 487
 488         if (existing) {
 489                 update_existing_head_ref(existing, ref);
 490                 /*
 491                  * we've updated the existing ref, free the newly
 492                  * allocated ref
 493                  */
 494                 kfree(head_ref);
 495         } else {
 496                 delayed_refs->num_heads++;
 497                 delayed_refs->num_heads_ready++;
 498                 delayed_refs->num_entries++;
 499                 trans->delayed_ref_updates++;
 500         }
 501 }
 502
 503 /*
 504  * helper to insert a delayed tree ref into the rbtree.
 505  */
 506 static noinline void add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 507                                          struct btrfs_trans_handle *trans,
 508                                          struct btrfs_delayed_ref_node *ref,
 509                                          u64 bytenr, u64 num_bytes, u64 parent,
 510                                          u64 ref_root, int level, int action,
 511                                          int for_cow)
 512 {
 513         struct btrfs_delayed_ref_node *existing;
 514         struct btrfs_delayed_tree_ref *full_ref;
 515         struct btrfs_delayed_ref_root *delayed_refs;
 516         u64 seq = 0;
 517
 518         if (action == BTRFS_ADD_DELAYED_EXTENT)
 519                 action = BTRFS_ADD_DELAYED_REF;
 520
 521         delayed_refs = &trans->transaction->delayed_refs;
 522
 523         /* first set the basic ref node struct up */
 524         atomic_set(&ref->refs, 1);
 525         ref->bytenr = bytenr;
 526         ref->num_bytes = num_bytes;
 527         ref->ref_mod = 1;
 528         ref->action = action;
 529         ref->is_head = 0;
 530         ref->in_tree = 1;
 531
 532         if (need_ref_seq(for_cow, ref_root))
 533                 seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 534         ref->seq = seq;
 535
 536         full_ref = btrfs_delayed_node_to_tree_ref(ref);
 537         full_ref->parent = parent;
 538         full_ref->root = ref_root;
 539         if (parent)
 540                 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
 541         else
 542                 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
 543         full_ref->level = level;
 544
 545         trace_btrfs_delayed_tree_ref(ref, full_ref, action);
 546
 547         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 548
 549         if (existing) {
 550                 update_existing_ref(trans, delayed_refs, existing, ref);
 551                 /*
 552                  * we've updated the existing ref, free the newly
 553                  * allocated ref
 554                  */
 555                 kfree(full_ref);
 556         } else {
 557                 delayed_refs->num_entries++;
 558                 trans->delayed_ref_updates++;
 559         }
 560 }
 561
 562 /*
 563  * helper to insert a delayed data ref into the rbtree.
 564  */
 565 static noinline void add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 566                                          struct btrfs_trans_handle *trans,
 567                                          struct btrfs_delayed_ref_node *ref,
 568                                          u64 bytenr, u64 num_bytes, u64 parent,
 569                                          u64 ref_root, u64 owner, u64 offset,
 570                                          int action, int for_cow)
 571 {
 572         struct btrfs_delayed_ref_node *existing;
 573         struct btrfs_delayed_data_ref *full_ref;
 574         struct btrfs_delayed_ref_root *delayed_refs;
 575         u64 seq = 0;
 576
 577         if (action == BTRFS_ADD_DELAYED_EXTENT)
 578                 action = BTRFS_ADD_DELAYED_REF;
 579
 580         delayed_refs = &trans->transaction->delayed_refs;
 581
 582         /* first set the basic ref node struct up */
 583         atomic_set(&ref->refs, 1);
 584         ref->bytenr = bytenr;
 585         ref->num_bytes = num_bytes;
 586         ref->ref_mod = 1;
 587         ref->action = action;
 588         ref->is_head = 0;
 589         ref->in_tree = 1;
 590
 591         if (need_ref_seq(for_cow, ref_root))
 592                 seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 593         ref->seq = seq;
 594
 595         full_ref = btrfs_delayed_node_to_data_ref(ref);
 596         full_ref->parent = parent;
 597         full_ref->root = ref_root;
 598         if (parent)
 599                 ref->type = BTRFS_SHARED_DATA_REF_KEY;
 600         else
 601                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
 602
 603         full_ref->objectid = owner;
 604         full_ref->offset = offset;
 605
 606         trace_btrfs_delayed_data_ref(ref, full_ref, action);
 607
 608         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 609
 610         if (existing) {
 611                 update_existing_ref(trans, delayed_refs, existing, ref);
 612                 /*
 613                  * we've updated the existing ref, free the newly
 614                  * allocated ref
 615                  */
 616                 kfree(full_ref);
 617         } else {
 618                 delayed_refs->num_entries++;
 619                 trans->delayed_ref_updates++;
 620         }
 621 }
 622
 623 /*
 624  * add a delayed tree ref.  This does all of the accounting required
 625  * to make sure the delayed ref is eventually processed before this
 626  * transaction commits.
 627  */
 628 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 629                                struct btrfs_trans_handle *trans,
 630                                u64 bytenr, u64 num_bytes, u64 parent,
 631                                u64 ref_root,  int level, int action,
 632                                struct btrfs_delayed_extent_op *extent_op,
 633                                int for_cow)
 634 {
 635         struct btrfs_delayed_tree_ref *ref;
 636         struct btrfs_delayed_ref_head *head_ref;
 637         struct btrfs_delayed_ref_root *delayed_refs;
 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         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 660                                    num_bytes, action, 0);
 661
 662         add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
 663                                    num_bytes, parent, ref_root, level, action,
 664                                    for_cow);
 665         spin_unlock(&delayed_refs->lock);
 666         if (need_ref_seq(for_cow, ref_root))
 667                 btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 668
 669         return 0;
 670 }
 671
 672 /*
 673  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 674  */
 675 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 676                                struct btrfs_trans_handle *trans,
 677                                u64 bytenr, u64 num_bytes,
 678                                u64 parent, u64 ref_root,
 679                                u64 owner, u64 offset, int action,
 680                                struct btrfs_delayed_extent_op *extent_op,
 681                                int for_cow)
 682 {
 683         struct btrfs_delayed_data_ref *ref;
 684         struct btrfs_delayed_ref_head *head_ref;
 685         struct btrfs_delayed_ref_root *delayed_refs;
 686
 687         BUG_ON(extent_op && !extent_op->is_data);
 688         ref = kmalloc(sizeof(*ref), GFP_NOFS);
 689         if (!ref)
 690                 return -ENOMEM;
 691
 692         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
 693         if (!head_ref) {
 694                 kfree(ref);
 695                 return -ENOMEM;
 696         }
 697
 698         head_ref->extent_op = extent_op;
 699
 700         delayed_refs = &trans->transaction->delayed_refs;
 701         spin_lock(&delayed_refs->lock);
 702
 703         /*
 704          * insert both the head node and the new ref without dropping
 705          * the spin lock
 706          */
 707         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 708                                    num_bytes, action, 1);
 709
 710         add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
 711                                    num_bytes, parent, ref_root, owner, offset,
 712                                    action, for_cow);
 713         spin_unlock(&delayed_refs->lock);
 714         if (need_ref_seq(for_cow, ref_root))
 715                 btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 716
 717         return 0;
 718 }
 719
 720 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 721                                 struct btrfs_trans_handle *trans,
 722                                 u64 bytenr, u64 num_bytes,
 723                                 struct btrfs_delayed_extent_op *extent_op)
 724 {
 725         struct btrfs_delayed_ref_head *head_ref;
 726         struct btrfs_delayed_ref_root *delayed_refs;
 727
 728         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
 729         if (!head_ref)
 730                 return -ENOMEM;
 731
 732         head_ref->extent_op = extent_op;
 733
 734         delayed_refs = &trans->transaction->delayed_refs;
 735         spin_lock(&delayed_refs->lock);
 736
 737         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 738                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
 739                                    extent_op->is_data);
 740
 741         spin_unlock(&delayed_refs->lock);
 742         return 0;
 743 }
 744
 745 /*
 746  * this does a simple search for the head node for a given extent.
 747  * It must be called with the delayed ref spinlock held, and it returns
 748  * the head node if any where found, or NULL if not.
 749  */
 750 struct btrfs_delayed_ref_head *
 751 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
 752 {
 753         struct btrfs_delayed_ref_node *ref;
 754         struct btrfs_delayed_ref_root *delayed_refs;
 755
 756         delayed_refs = &trans->transaction->delayed_refs;
 757         ref = find_ref_head(&delayed_refs->root, bytenr, NULL, 0);
 758         if (ref)
 759                 return btrfs_delayed_node_to_head(ref);
 760         return NULL;
 761 }