fs/btrfs/delayed-ref.c

   1 /*
   2  * Copyright (C) 2009 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/slab.h>
  21 #include <linux/sort.h>
  22 #include "ctree.h"
  23 #include "delayed-ref.h"
  24 #include "transaction.h"
  25
  26 /*
  27  * delayed back reference update tracking.  For subvolume trees
  28  * we queue up extent allocations and backref maintenance for
  29  * delayed processing.   This avoids deep call chains where we
  30  * add extents in the middle of btrfs_search_slot, and it allows
  31  * us to buffer up frequently modified backrefs in an rb tree instead
  32  * of hammering updates on the extent allocation tree.
  33  */
  34
  35 /*
  36  * compare two delayed tree backrefs with same bytenr and type
  37  */
  38 static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref2,
  39                           struct btrfs_delayed_tree_ref *ref1)
  40 {
  41         if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) {
  42                 if (ref1->root < ref2->root)
  43                         return -1;
  44                 if (ref1->root > ref2->root)
  45                         return 1;
  46         } else {
  47                 if (ref1->parent < ref2->parent)
  48                         return -1;
  49                 if (ref1->parent > ref2->parent)
  50                         return 1;
  51         }
  52         return 0;
  53 }
  54
  55 /*
  56  * compare two delayed data backrefs with same bytenr and type
  57  */
  58 static int comp_data_refs(struct btrfs_delayed_data_ref *ref2,
  59                           struct btrfs_delayed_data_ref *ref1)
  60 {
  61         if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
  62                 if (ref1->root < ref2->root)
  63                         return -1;
  64                 if (ref1->root > ref2->root)
  65                         return 1;
  66                 if (ref1->objectid < ref2->objectid)
  67                         return -1;
  68                 if (ref1->objectid > ref2->objectid)
  69                         return 1;
  70                 if (ref1->offset < ref2->offset)
  71                         return -1;
  72                 if (ref1->offset > ref2->offset)
  73                         return 1;
  74         } else {
  75                 if (ref1->parent < ref2->parent)
  76                         return -1;
  77                 if (ref1->parent > ref2->parent)
  78                         return 1;
  79         }
  80         return 0;
  81 }
  82
  83 /*
  84  * entries in the rb tree are ordered by the byte number of the extent,
  85  * type of the delayed backrefs and content of delayed backrefs.
  86  */
  87 static int comp_entry(struct btrfs_delayed_ref_node *ref2,
  88                       struct btrfs_delayed_ref_node *ref1)
  89 {
  90         if (ref1->bytenr < ref2->bytenr)
  91                 return -1;
  92         if (ref1->bytenr > ref2->bytenr)
  93                 return 1;
  94         if (ref1->is_head && ref2->is_head)
  95                 return 0;
  96         if (ref2->is_head)
  97                 return -1;
  98         if (ref1->is_head)
  99                 return 1;
 100         if (ref1->type < ref2->type)
 101                 return -1;
 102         if (ref1->type > ref2->type)
 103                 return 1;
 104         /* merging of sequenced refs is not allowed */
 105         if (ref1->seq < ref2->seq)
 106                 return -1;
 107         if (ref1->seq > ref2->seq)
 108                 return 1;
 109         if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
 110             ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) {
 111                 return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2),
 112                                       btrfs_delayed_node_to_tree_ref(ref1));
 113         } else if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY ||
 114                    ref1->type == BTRFS_SHARED_DATA_REF_KEY) {
 115                 return comp_data_refs(btrfs_delayed_node_to_data_ref(ref2),
 116                                       btrfs_delayed_node_to_data_ref(ref1));
 117         }
 118         BUG();
 119         return 0;
 120 }
 121
 122 /*
 123  * insert a new ref into the rbtree.  This returns any existing refs
 124  * for the same (bytenr,parent) tuple, or NULL if the new node was properly
 125  * inserted.
 126  */
 127 static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root,
 128                                                   struct rb_node *node)
 129 {
 130         struct rb_node **p = &root->rb_node;
 131         struct rb_node *parent_node = NULL;
 132         struct btrfs_delayed_ref_node *entry;
 133         struct btrfs_delayed_ref_node *ins;
 134         int cmp;
 135
 136         ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 137         while (*p) {
 138                 parent_node = *p;
 139                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
 140                                  rb_node);
 141
 142                 cmp = comp_entry(entry, ins);
 143                 if (cmp < 0)
 144                         p = &(*p)->rb_left;
 145                 else if (cmp > 0)
 146                         p = &(*p)->rb_right;
 147                 else
 148                         return entry;
 149         }
 150
 151         rb_link_node(node, parent_node, p);
 152         rb_insert_color(node, root);
 153         return NULL;
 154 }
 155
 156 /*
 157  * find an head entry based on bytenr. This returns the delayed ref
 158  * head if it was able to find one, or NULL if nothing was in that spot.
 159  * If return_bigger is given, the next bigger entry is returned if no exact
 160  * match is found.
 161  */
 162 static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root,
 163                                   u64 bytenr,
 164                                   struct btrfs_delayed_ref_node **last,
 165                                   int return_bigger)
 166 {
 167         struct rb_node *n;
 168         struct btrfs_delayed_ref_node *entry;
 169         int cmp = 0;
 170
 171 again:
 172         n = root->rb_node;
 173         entry = NULL;
 174         while (n) {
 175                 entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
 176                 WARN_ON(!entry->in_tree);
 177                 if (last)
 178                         *last = entry;
 179
 180                 if (bytenr < entry->bytenr)
 181                         cmp = -1;
 182                 else if (bytenr > entry->bytenr)
 183                         cmp = 1;
 184                 else if (!btrfs_delayed_ref_is_head(entry))
 185                         cmp = 1;
 186                 else
 187                         cmp = 0;
 188
 189                 if (cmp < 0)
 190                         n = n->rb_left;
 191                 else if (cmp > 0)
 192                         n = n->rb_right;
 193                 else
 194                         return entry;
 195         }
 196         if (entry && return_bigger) {
 197                 if (cmp > 0) {
 198                         n = rb_next(&entry->rb_node);
 199                         if (!n)
 200                                 n = rb_first(root);
 201                         entry = rb_entry(n, struct btrfs_delayed_ref_node,
 202                                          rb_node);
 203                         bytenr = entry->bytenr;
 204                         return_bigger = 0;
 205                         goto again;
 206                 }
 207                 return entry;
 208         }
 209         return NULL;
 210 }
 211
 212 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 213                            struct btrfs_delayed_ref_head *head)
 214 {
 215         struct btrfs_delayed_ref_root *delayed_refs;
 216
 217         delayed_refs = &trans->transaction->delayed_refs;
 218         assert_spin_locked(&delayed_refs->lock);
 219         if (mutex_trylock(&head->mutex))
 220                 return 0;
 221
 222         atomic_inc(&head->node.refs);
 223         spin_unlock(&delayed_refs->lock);
 224
 225         mutex_lock(&head->mutex);
 226         spin_lock(&delayed_refs->lock);
 227         if (!head->node.in_tree) {
 228                 mutex_unlock(&head->mutex);
 229                 btrfs_put_delayed_ref(&head->node);
 230                 return -EAGAIN;
 231         }
 232         btrfs_put_delayed_ref(&head->node);
 233         return 0;
 234 }
 235
 236 int btrfs_check_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs,
 237                             u64 seq)
 238 {
 239         struct seq_list *elem;
 240
 241         assert_spin_locked(&delayed_refs->lock);
 242         if (list_empty(&delayed_refs->seq_head))
 243                 return 0;
 244
 245         elem = list_first_entry(&delayed_refs->seq_head, struct seq_list, list);
 246         if (seq >= elem->seq) {
 247                 pr_debug("holding back delayed_ref %llu, lowest is %llu (%p)\n",
 248                          seq, elem->seq, delayed_refs);
 249                 return 1;
 250         }
 251         return 0;
 252 }
 253
 254 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
 255                            struct list_head *cluster, u64 start)
 256 {
 257         int count = 0;
 258         struct btrfs_delayed_ref_root *delayed_refs;
 259         struct rb_node *node;
 260         struct btrfs_delayed_ref_node *ref;
 261         struct btrfs_delayed_ref_head *head;
 262
 263         delayed_refs = &trans->transaction->delayed_refs;
 264         if (start == 0) {
 265                 node = rb_first(&delayed_refs->root);
 266         } else {
 267                 ref = NULL;
 268                 find_ref_head(&delayed_refs->root, start + 1, &ref, 1);
 269                 if (ref) {
 270                         node = &ref->rb_node;
 271                 } else
 272                         node = rb_first(&delayed_refs->root);
 273         }
 274 again:
 275         while (node && count < 32) {
 276                 ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 277                 if (btrfs_delayed_ref_is_head(ref)) {
 278                         head = btrfs_delayed_node_to_head(ref);
 279                         if (list_empty(&head->cluster)) {
 280                                 list_add_tail(&head->cluster, cluster);
 281                                 delayed_refs->run_delayed_start =
 282                                         head->node.bytenr;
 283                                 count++;
 284
 285                                 WARN_ON(delayed_refs->num_heads_ready == 0);
 286                                 delayed_refs->num_heads_ready--;
 287                         } else if (count) {
 288                                 /* the goal of the clustering is to find extents
 289                                  * that are likely to end up in the same extent
 290                                  * leaf on disk.  So, we don't want them spread
 291                                  * all over the tree.  Stop now if we've hit
 292                                  * a head that was already in use
 293                                  */
 294                                 break;
 295                         }
 296                 }
 297                 node = rb_next(node);
 298         }
 299         if (count) {
 300                 return 0;
 301         } else if (start) {
 302                 /*
 303                  * we've gone to the end of the rbtree without finding any
 304                  * clusters.  start from the beginning and try again
 305                  */
 306                 start = 0;
 307                 node = rb_first(&delayed_refs->root);
 308                 goto again;
 309         }
 310         return 1;
 311 }
 312
 313 /*
 314  * helper function to update an extent delayed ref in the
 315  * rbtree.  existing and update must both have the same
 316  * bytenr and parent
 317  *
 318  * This may free existing if the update cancels out whatever
 319  * operation it was doing.
 320  */
 321 static noinline void
 322 update_existing_ref(struct btrfs_trans_handle *trans,
 323                     struct btrfs_delayed_ref_root *delayed_refs,
 324                     struct btrfs_delayed_ref_node *existing,
 325                     struct btrfs_delayed_ref_node *update)
 326 {
 327         if (update->action != existing->action) {
 328                 /*
 329                  * this is effectively undoing either an add or a
 330                  * drop.  We decrement the ref_mod, and if it goes
 331                  * down to zero we just delete the entry without
 332                  * every changing the extent allocation tree.
 333                  */
 334                 existing->ref_mod--;
 335                 if (existing->ref_mod == 0) {
 336                         rb_erase(&existing->rb_node,
 337                                  &delayed_refs->root);
 338                         existing->in_tree = 0;
 339                         btrfs_put_delayed_ref(existing);
 340                         delayed_refs->num_entries--;
 341                         if (trans->delayed_ref_updates)
 342                                 trans->delayed_ref_updates--;
 343                 } else {
 344                         WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 345                                 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 346                 }
 347         } else {
 348                 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 349                         existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 350                 /*
 351                  * the action on the existing ref matches
 352                  * the action on the ref we're trying to add.
 353                  * Bump the ref_mod by one so the backref that
 354                  * is eventually added/removed has the correct
 355                  * reference count
 356                  */
 357                 existing->ref_mod += update->ref_mod;
 358         }
 359 }
 360
 361 /*
 362  * helper function to update the accounting in the head ref
 363  * existing and update must have the same bytenr
 364  */
 365 static noinline void
 366 update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
 367                          struct btrfs_delayed_ref_node *update)
 368 {
 369         struct btrfs_delayed_ref_head *existing_ref;
 370         struct btrfs_delayed_ref_head *ref;
 371
 372         existing_ref = btrfs_delayed_node_to_head(existing);
 373         ref = btrfs_delayed_node_to_head(update);
 374         BUG_ON(existing_ref->is_data != ref->is_data);
 375
 376         if (ref->must_insert_reserved) {
 377                 /* if the extent was freed and then
 378                  * reallocated before the delayed ref
 379                  * entries were processed, we can end up
 380                  * with an existing head ref without
 381                  * the must_insert_reserved flag set.
 382                  * Set it again here
 383                  */
 384                 existing_ref->must_insert_reserved = ref->must_insert_reserved;
 385
 386                 /*
 387                  * update the num_bytes so we make sure the accounting
 388                  * is done correctly
 389                  */
 390                 existing->num_bytes = update->num_bytes;
 391
 392         }
 393
 394         if (ref->extent_op) {
 395                 if (!existing_ref->extent_op) {
 396                         existing_ref->extent_op = ref->extent_op;
 397                 } else {
 398                         if (ref->extent_op->update_key) {
 399                                 memcpy(&existing_ref->extent_op->key,
 400                                        &ref->extent_op->key,
 401                                        sizeof(ref->extent_op->key));
 402                                 existing_ref->extent_op->update_key = 1;
 403                         }
 404                         if (ref->extent_op->update_flags) {
 405                                 existing_ref->extent_op->flags_to_set |=
 406                                         ref->extent_op->flags_to_set;
 407                                 existing_ref->extent_op->update_flags = 1;
 408                         }
 409                         kfree(ref->extent_op);
 410                 }
 411         }
 412         /*
 413          * update the reference mod on the head to reflect this new operation
 414          */
 415         existing->ref_mod += update->ref_mod;
 416 }
 417
 418 /*
 419  * helper function to actually insert a head node into the rbtree.
 420  * this does all the dirty work in terms of maintaining the correct
 421  * overall modification count.
 422  */
 423 static noinline void add_delayed_ref_head(struct btrfs_fs_info *fs_info,
 424                                         struct btrfs_trans_handle *trans,
 425                                         struct btrfs_delayed_ref_node *ref,
 426                                         u64 bytenr, u64 num_bytes,
 427                                         int action, int is_data)
 428 {
 429         struct btrfs_delayed_ref_node *existing;
 430         struct btrfs_delayed_ref_head *head_ref = NULL;
 431         struct btrfs_delayed_ref_root *delayed_refs;
 432         int count_mod = 1;
 433         int must_insert_reserved = 0;
 434
 435         /*
 436          * the head node stores the sum of all the mods, so dropping a ref
 437          * should drop the sum in the head node by one.
 438          */
 439         if (action == BTRFS_UPDATE_DELAYED_HEAD)
 440                 count_mod = 0;
 441         else if (action == BTRFS_DROP_DELAYED_REF)
 442                 count_mod = -1;
 443
 444         /*
 445          * BTRFS_ADD_DELAYED_EXTENT means that we need to update
 446          * the reserved accounting when the extent is finally added, or
 447          * if a later modification deletes the delayed ref without ever
 448          * inserting the extent into the extent allocation tree.
 449          * ref->must_insert_reserved is the flag used to record
 450          * that accounting mods are required.
 451          *
 452          * Once we record must_insert_reserved, switch the action to
 453          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
 454          */
 455         if (action == BTRFS_ADD_DELAYED_EXTENT)
 456                 must_insert_reserved = 1;
 457         else
 458                 must_insert_reserved = 0;
 459
 460         delayed_refs = &trans->transaction->delayed_refs;
 461
 462         /* first set the basic ref node struct up */
 463         atomic_set(&ref->refs, 1);
 464         ref->bytenr = bytenr;
 465         ref->num_bytes = num_bytes;
 466         ref->ref_mod = count_mod;
 467         ref->type  = 0;
 468         ref->action  = 0;
 469         ref->is_head = 1;
 470         ref->in_tree = 1;
 471         ref->seq = 0;
 472
 473         head_ref = btrfs_delayed_node_to_head(ref);
 474         head_ref->must_insert_reserved = must_insert_reserved;
 475         head_ref->is_data = is_data;
 476
 477         INIT_LIST_HEAD(&head_ref->cluster);
 478         mutex_init(&head_ref->mutex);
 479
 480         trace_btrfs_delayed_ref_head(ref, head_ref, action);
 481
 482         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 483
 484         if (existing) {
 485                 update_existing_head_ref(existing, ref);
 486                 /*
 487                  * we've updated the existing ref, free the newly
 488                  * allocated ref
 489                  */
 490                 kfree(head_ref);
 491         } else {
 492                 delayed_refs->num_heads++;
 493                 delayed_refs->num_heads_ready++;
 494                 delayed_refs->num_entries++;
 495                 trans->delayed_ref_updates++;
 496         }
 497 }
 498
 499 /*
 500  * helper to insert a delayed tree ref into the rbtree.
 501  */
 502 static noinline void add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 503                                          struct btrfs_trans_handle *trans,
 504                                          struct btrfs_delayed_ref_node *ref,
 505                                          u64 bytenr, u64 num_bytes, u64 parent,
 506                                          u64 ref_root, int level, int action,
 507                                          int for_cow)
 508 {
 509         struct btrfs_delayed_ref_node *existing;
 510         struct btrfs_delayed_tree_ref *full_ref;
 511         struct btrfs_delayed_ref_root *delayed_refs;
 512         u64 seq = 0;
 513
 514         if (action == BTRFS_ADD_DELAYED_EXTENT)
 515                 action = BTRFS_ADD_DELAYED_REF;
 516
 517         delayed_refs = &trans->transaction->delayed_refs;
 518
 519         /* first set the basic ref node struct up */
 520         atomic_set(&ref->refs, 1);
 521         ref->bytenr = bytenr;
 522         ref->num_bytes = num_bytes;
 523         ref->ref_mod = 1;
 524         ref->action = action;
 525         ref->is_head = 0;
 526         ref->in_tree = 1;
 527
 528         if (need_ref_seq(for_cow, ref_root))
 529                 seq = inc_delayed_seq(delayed_refs);
 530         ref->seq = seq;
 531
 532         full_ref = btrfs_delayed_node_to_tree_ref(ref);
 533         full_ref->parent = parent;
 534         full_ref->root = ref_root;
 535         if (parent)
 536                 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
 537         else
 538                 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
 539         full_ref->level = level;
 540
 541         trace_btrfs_delayed_tree_ref(ref, full_ref, action);
 542
 543         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 544
 545         if (existing) {
 546                 update_existing_ref(trans, delayed_refs, existing, ref);
 547                 /*
 548                  * we've updated the existing ref, free the newly
 549                  * allocated ref
 550                  */
 551                 kfree(full_ref);
 552         } else {
 553                 delayed_refs->num_entries++;
 554                 trans->delayed_ref_updates++;
 555         }
 556 }
 557
 558 /*
 559  * helper to insert a delayed data ref into the rbtree.
 560  */
 561 static noinline void add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 562                                          struct btrfs_trans_handle *trans,
 563                                          struct btrfs_delayed_ref_node *ref,
 564                                          u64 bytenr, u64 num_bytes, u64 parent,
 565                                          u64 ref_root, u64 owner, u64 offset,
 566                                          int action, int for_cow)
 567 {
 568         struct btrfs_delayed_ref_node *existing;
 569         struct btrfs_delayed_data_ref *full_ref;
 570         struct btrfs_delayed_ref_root *delayed_refs;
 571         u64 seq = 0;
 572
 573         if (action == BTRFS_ADD_DELAYED_EXTENT)
 574                 action = BTRFS_ADD_DELAYED_REF;
 575
 576         delayed_refs = &trans->transaction->delayed_refs;
 577
 578         /* first set the basic ref node struct up */
 579         atomic_set(&ref->refs, 1);
 580         ref->bytenr = bytenr;
 581         ref->num_bytes = num_bytes;
 582         ref->ref_mod = 1;
 583         ref->action = action;
 584         ref->is_head = 0;
 585         ref->in_tree = 1;
 586
 587         if (need_ref_seq(for_cow, ref_root))
 588                 seq = inc_delayed_seq(delayed_refs);
 589         ref->seq = seq;
 590
 591         full_ref = btrfs_delayed_node_to_data_ref(ref);
 592         full_ref->parent = parent;
 593         full_ref->root = ref_root;
 594         if (parent)
 595                 ref->type = BTRFS_SHARED_DATA_REF_KEY;
 596         else
 597                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
 598
 599         full_ref->objectid = owner;
 600         full_ref->offset = offset;
 601
 602         trace_btrfs_delayed_data_ref(ref, full_ref, action);
 603
 604         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 605
 606         if (existing) {
 607                 update_existing_ref(trans, delayed_refs, existing, ref);
 608                 /*
 609                  * we've updated the existing ref, free the newly
 610                  * allocated ref
 611                  */
 612                 kfree(full_ref);
 613         } else {
 614                 delayed_refs->num_entries++;
 615                 trans->delayed_ref_updates++;
 616         }
 617 }
 618
 619 /*
 620  * add a delayed tree ref.  This does all of the accounting required
 621  * to make sure the delayed ref is eventually processed before this
 622  * transaction commits.
 623  */
 624 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 625                                struct btrfs_trans_handle *trans,
 626                                u64 bytenr, u64 num_bytes, u64 parent,
 627                                u64 ref_root,  int level, int action,
 628                                struct btrfs_delayed_extent_op *extent_op,
 629                                int for_cow)
 630 {
 631         struct btrfs_delayed_tree_ref *ref;
 632         struct btrfs_delayed_ref_head *head_ref;
 633         struct btrfs_delayed_ref_root *delayed_refs;
 634
 635         BUG_ON(extent_op && extent_op->is_data);
 636         ref = kmalloc(sizeof(*ref), GFP_NOFS);
 637         if (!ref)
 638                 return -ENOMEM;
 639
 640         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
 641         if (!head_ref) {
 642                 kfree(ref);
 643                 return -ENOMEM;
 644         }
 645
 646         head_ref->extent_op = extent_op;
 647
 648         delayed_refs = &trans->transaction->delayed_refs;
 649         spin_lock(&delayed_refs->lock);
 650
 651         /*
 652          * insert both the head node and the new ref without dropping
 653          * the spin lock
 654          */
 655         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 656                                    num_bytes, action, 0);
 657
 658         add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
 659                                    num_bytes, parent, ref_root, level, action,
 660                                    for_cow);
 661         if (!need_ref_seq(for_cow, ref_root) &&
 662             waitqueue_active(&delayed_refs->seq_wait))
 663                 wake_up(&delayed_refs->seq_wait);
 664         spin_unlock(&delayed_refs->lock);
 665         return 0;
 666 }
 667
 668 /*
 669  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 670  */
 671 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 672                                struct btrfs_trans_handle *trans,
 673                                u64 bytenr, u64 num_bytes,
 674                                u64 parent, u64 ref_root,
 675                                u64 owner, u64 offset, int action,
 676                                struct btrfs_delayed_extent_op *extent_op,
 677                                int for_cow)
 678 {
 679         struct btrfs_delayed_data_ref *ref;
 680         struct btrfs_delayed_ref_head *head_ref;
 681         struct btrfs_delayed_ref_root *delayed_refs;
 682
 683         BUG_ON(extent_op && !extent_op->is_data);
 684         ref = kmalloc(sizeof(*ref), GFP_NOFS);
 685         if (!ref)
 686                 return -ENOMEM;
 687
 688         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
 689         if (!head_ref) {
 690                 kfree(ref);
 691                 return -ENOMEM;
 692         }
 693
 694         head_ref->extent_op = extent_op;
 695
 696         delayed_refs = &trans->transaction->delayed_refs;
 697         spin_lock(&delayed_refs->lock);
 698
 699         /*
 700          * insert both the head node and the new ref without dropping
 701          * the spin lock
 702          */
 703         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 704                                    num_bytes, action, 1);
 705
 706         add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
 707                                    num_bytes, parent, ref_root, owner, offset,
 708                                    action, for_cow);
 709         if (!need_ref_seq(for_cow, ref_root) &&
 710             waitqueue_active(&delayed_refs->seq_wait))
 711                 wake_up(&delayed_refs->seq_wait);
 712         spin_unlock(&delayed_refs->lock);
 713         return 0;
 714 }
 715
 716 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 717                                 struct btrfs_trans_handle *trans,
 718                                 u64 bytenr, u64 num_bytes,
 719                                 struct btrfs_delayed_extent_op *extent_op)
 720 {
 721         struct btrfs_delayed_ref_head *head_ref;
 722         struct btrfs_delayed_ref_root *delayed_refs;
 723
 724         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
 725         if (!head_ref)
 726                 return -ENOMEM;
 727
 728         head_ref->extent_op = extent_op;
 729
 730         delayed_refs = &trans->transaction->delayed_refs;
 731         spin_lock(&delayed_refs->lock);
 732
 733         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 734                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
 735                                    extent_op->is_data);
 736
 737         if (waitqueue_active(&delayed_refs->seq_wait))
 738                 wake_up(&delayed_refs->seq_wait);
 739         spin_unlock(&delayed_refs->lock);
 740         return 0;
 741 }
 742
 743 /*
 744  * this does a simple search for the head node for a given extent.
 745  * It must be called with the delayed ref spinlock held, and it returns
 746  * the head node if any where found, or NULL if not.
 747  */
 748 struct btrfs_delayed_ref_head *
 749 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
 750 {
 751         struct btrfs_delayed_ref_node *ref;
 752         struct btrfs_delayed_ref_root *delayed_refs;
 753
 754         delayed_refs = &trans->transaction->delayed_refs;
 755         ref = find_ref_head(&delayed_refs->root, bytenr, NULL, 0);
 756         if (ref)
 757                 return btrfs_delayed_node_to_head(ref);
 758         return NULL;
 759 }