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 struct kmem_cache *btrfs_delayed_ref_head_cachep;
  27 struct kmem_cache *btrfs_delayed_tree_ref_cachep;
  28 struct kmem_cache *btrfs_delayed_data_ref_cachep;
  29 struct kmem_cache *btrfs_delayed_extent_op_cachep;
  30 /*
  31  * delayed back reference update tracking.  For subvolume trees
  32  * we queue up extent allocations and backref maintenance for
  33  * delayed processing.   This avoids deep call chains where we
  34  * add extents in the middle of btrfs_search_slot, and it allows
  35  * us to buffer up frequently modified backrefs in an rb tree instead
  36  * of hammering updates on the extent allocation tree.
  37  */
  38
  39 /*
  40  * compare two delayed tree backrefs with same bytenr and type
  41  */
  42 static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref2,
  43                           struct btrfs_delayed_tree_ref *ref1, int type)
  44 {
  45         if (type == BTRFS_TREE_BLOCK_REF_KEY) {
  46                 if (ref1->root < ref2->root)
  47                         return -1;
  48                 if (ref1->root > ref2->root)
  49                         return 1;
  50         } else {
  51                 if (ref1->parent < ref2->parent)
  52                         return -1;
  53                 if (ref1->parent > ref2->parent)
  54                         return 1;
  55         }
  56         return 0;
  57 }
  58
  59 /*
  60  * compare two delayed data backrefs with same bytenr and type
  61  */
  62 static int comp_data_refs(struct btrfs_delayed_data_ref *ref2,
  63                           struct btrfs_delayed_data_ref *ref1)
  64 {
  65         if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
  66                 if (ref1->root < ref2->root)
  67                         return -1;
  68                 if (ref1->root > ref2->root)
  69                         return 1;
  70                 if (ref1->objectid < ref2->objectid)
  71                         return -1;
  72                 if (ref1->objectid > ref2->objectid)
  73                         return 1;
  74                 if (ref1->offset < ref2->offset)
  75                         return -1;
  76                 if (ref1->offset > ref2->offset)
  77                         return 1;
  78         } else {
  79                 if (ref1->parent < ref2->parent)
  80                         return -1;
  81                 if (ref1->parent > ref2->parent)
  82                         return 1;
  83         }
  84         return 0;
  85 }
  86
  87 /*
  88  * entries in the rb tree are ordered by the byte number of the extent,
  89  * type of the delayed backrefs and content of delayed backrefs.
  90  */
  91 static int comp_entry(struct btrfs_delayed_ref_node *ref2,
  92                       struct btrfs_delayed_ref_node *ref1,
  93                       bool compare_seq)
  94 {
  95         if (ref1->bytenr < ref2->bytenr)
  96                 return -1;
  97         if (ref1->bytenr > ref2->bytenr)
  98                 return 1;
  99         if (ref1->is_head && ref2->is_head)
 100                 return 0;
 101         if (ref2->is_head)
 102                 return -1;
 103         if (ref1->is_head)
 104                 return 1;
 105         if (ref1->type < ref2->type)
 106                 return -1;
 107         if (ref1->type > ref2->type)
 108                 return 1;
 109         /* merging of sequenced refs is not allowed */
 110         if (compare_seq) {
 111                 if (ref1->seq < ref2->seq)
 112                         return -1;
 113                 if (ref1->seq > ref2->seq)
 114                         return 1;
 115         }
 116         if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
 117             ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) {
 118                 return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2),
 119                                       btrfs_delayed_node_to_tree_ref(ref1),
 120                                       ref1->type);
 121         } else if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY ||
 122                    ref1->type == BTRFS_SHARED_DATA_REF_KEY) {
 123                 return comp_data_refs(btrfs_delayed_node_to_data_ref(ref2),
 124                                       btrfs_delayed_node_to_data_ref(ref1));
 125         }
 126         BUG();
 127         return 0;
 128 }
 129
 130 /*
 131  * insert a new ref into the rbtree.  This returns any existing refs
 132  * for the same (bytenr,parent) tuple, or NULL if the new node was properly
 133  * inserted.
 134  */
 135 static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root,
 136                                                   struct rb_node *node)
 137 {
 138         struct rb_node **p = &root->rb_node;
 139         struct rb_node *parent_node = NULL;
 140         struct btrfs_delayed_ref_node *entry;
 141         struct btrfs_delayed_ref_node *ins;
 142         int cmp;
 143
 144         ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 145         while (*p) {
 146                 parent_node = *p;
 147                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
 148                                  rb_node);
 149
 150                 cmp = comp_entry(entry, ins, 1);
 151                 if (cmp < 0)
 152                         p = &(*p)->rb_left;
 153                 else if (cmp > 0)
 154                         p = &(*p)->rb_right;
 155                 else
 156                         return entry;
 157         }
 158
 159         rb_link_node(node, parent_node, p);
 160         rb_insert_color(node, root);
 161         return NULL;
 162 }
 163
 164 /*
 165  * find an head entry based on bytenr. This returns the delayed ref
 166  * head if it was able to find one, or NULL if nothing was in that spot.
 167  * If return_bigger is given, the next bigger entry is returned if no exact
 168  * match is found.
 169  */
 170 static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root,
 171                                   u64 bytenr,
 172                                   struct btrfs_delayed_ref_node **last,
 173                                   int return_bigger)
 174 {
 175         struct rb_node *n;
 176         struct btrfs_delayed_ref_node *entry;
 177         int cmp = 0;
 178
 179 again:
 180         n = root->rb_node;
 181         entry = NULL;
 182         while (n) {
 183                 entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
 184                 WARN_ON(!entry->in_tree);
 185                 if (last)
 186                         *last = entry;
 187
 188                 if (bytenr < entry->bytenr)
 189                         cmp = -1;
 190                 else if (bytenr > entry->bytenr)
 191                         cmp = 1;
 192                 else if (!btrfs_delayed_ref_is_head(entry))
 193                         cmp = 1;
 194                 else
 195                         cmp = 0;
 196
 197                 if (cmp < 0)
 198                         n = n->rb_left;
 199                 else if (cmp > 0)
 200                         n = n->rb_right;
 201                 else
 202                         return entry;
 203         }
 204         if (entry && return_bigger) {
 205                 if (cmp > 0) {
 206                         n = rb_next(&entry->rb_node);
 207                         if (!n)
 208                                 n = rb_first(root);
 209                         entry = rb_entry(n, struct btrfs_delayed_ref_node,
 210                                          rb_node);
 211                         bytenr = entry->bytenr;
 212                         return_bigger = 0;
 213                         goto again;
 214                 }
 215                 return entry;
 216         }
 217         return NULL;
 218 }
 219
 220 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 221                            struct btrfs_delayed_ref_head *head)
 222 {
 223         struct btrfs_delayed_ref_root *delayed_refs;
 224
 225         delayed_refs = &trans->transaction->delayed_refs;
 226         assert_spin_locked(&delayed_refs->lock);
 227         if (mutex_trylock(&head->mutex))
 228                 return 0;
 229
 230         atomic_inc(&head->node.refs);
 231         spin_unlock(&delayed_refs->lock);
 232
 233         mutex_lock(&head->mutex);
 234         spin_lock(&delayed_refs->lock);
 235         if (!head->node.in_tree) {
 236                 mutex_unlock(&head->mutex);
 237                 btrfs_put_delayed_ref(&head->node);
 238                 return -EAGAIN;
 239         }
 240         btrfs_put_delayed_ref(&head->node);
 241         return 0;
 242 }
 243
 244 static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
 245                                     struct btrfs_delayed_ref_root *delayed_refs,
 246                                     struct btrfs_delayed_ref_node *ref)
 247 {
 248         rb_erase(&ref->rb_node, &delayed_refs->root);
 249         ref->in_tree = 0;
 250         btrfs_put_delayed_ref(ref);
 251         delayed_refs->num_entries--;
 252         if (trans->delayed_ref_updates)
 253                 trans->delayed_ref_updates--;
 254 }
 255
 256 static int merge_ref(struct btrfs_trans_handle *trans,
 257                      struct btrfs_delayed_ref_root *delayed_refs,
 258                      struct btrfs_delayed_ref_node *ref, u64 seq)
 259 {
 260         struct rb_node *node;
 261         int merged = 0;
 262         int mod = 0;
 263         int done = 0;
 264
 265         node = rb_prev(&ref->rb_node);
 266         while (node) {
 267                 struct btrfs_delayed_ref_node *next;
 268
 269                 next = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 270                 node = rb_prev(node);
 271                 if (next->bytenr != ref->bytenr)
 272                         break;
 273                 if (seq && next->seq >= seq)
 274                         break;
 275                 if (comp_entry(ref, next, 0))
 276                         continue;
 277
 278                 if (ref->action == next->action) {
 279                         mod = next->ref_mod;
 280                 } else {
 281                         if (ref->ref_mod < next->ref_mod) {
 282                                 struct btrfs_delayed_ref_node *tmp;
 283
 284                                 tmp = ref;
 285                                 ref = next;
 286                                 next = tmp;
 287                                 done = 1;
 288                         }
 289                         mod = -next->ref_mod;
 290                 }
 291
 292                 merged++;
 293                 drop_delayed_ref(trans, delayed_refs, next);
 294                 ref->ref_mod += mod;
 295                 if (ref->ref_mod == 0) {
 296                         drop_delayed_ref(trans, delayed_refs, ref);
 297                         break;
 298                 } else {
 299                         /*
 300                          * You can't have multiples of the same ref on a tree
 301                          * block.
 302                          */
 303                         WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
 304                                 ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
 305                 }
 306
 307                 if (done)
 308                         break;
 309                 node = rb_prev(&ref->rb_node);
 310         }
 311
 312         return merged;
 313 }
 314
 315 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 316                               struct btrfs_fs_info *fs_info,
 317                               struct btrfs_delayed_ref_root *delayed_refs,
 318                               struct btrfs_delayed_ref_head *head)
 319 {
 320         struct rb_node *node;
 321         u64 seq = 0;
 322
 323         spin_lock(&fs_info->tree_mod_seq_lock);
 324         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 325                 struct seq_list *elem;
 326
 327                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 328                                         struct seq_list, list);
 329                 seq = elem->seq;
 330         }
 331         spin_unlock(&fs_info->tree_mod_seq_lock);
 332
 333         node = rb_prev(&head->node.rb_node);
 334         while (node) {
 335                 struct btrfs_delayed_ref_node *ref;
 336
 337                 ref = rb_entry(node, struct btrfs_delayed_ref_node,
 338                                rb_node);
 339                 if (ref->bytenr != head->node.bytenr)
 340                         break;
 341
 342                 /* We can't merge refs that are outside of our seq count */
 343                 if (seq && ref->seq >= seq)
 344                         break;
 345                 if (merge_ref(trans, delayed_refs, ref, seq))
 346                         node = rb_prev(&head->node.rb_node);
 347                 else
 348                         node = rb_prev(node);
 349         }
 350 }
 351
 352 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 353                             struct btrfs_delayed_ref_root *delayed_refs,
 354                             u64 seq)
 355 {
 356         struct seq_list *elem;
 357         int ret = 0;
 358
 359         spin_lock(&fs_info->tree_mod_seq_lock);
 360         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 361                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 362                                         struct seq_list, list);
 363                 if (seq >= elem->seq) {
 364                         pr_debug("holding back delayed_ref %#x.%x, lowest is %#x.%x (%p)\n",
 365                                  (u32)(seq >> 32), (u32)seq,
 366                                  (u32)(elem->seq >> 32), (u32)elem->seq,
 367                                  delayed_refs);
 368                         ret = 1;
 369                 }
 370         }
 371
 372         spin_unlock(&fs_info->tree_mod_seq_lock);
 373         return ret;
 374 }
 375
 376 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
 377                            struct list_head *cluster, u64 start)
 378 {
 379         int count = 0;
 380         struct btrfs_delayed_ref_root *delayed_refs;
 381         struct rb_node *node;
 382         struct btrfs_delayed_ref_node *ref;
 383         struct btrfs_delayed_ref_head *head;
 384
 385         delayed_refs = &trans->transaction->delayed_refs;
 386         if (start == 0) {
 387                 node = rb_first(&delayed_refs->root);
 388         } else {
 389                 ref = NULL;
 390                 find_ref_head(&delayed_refs->root, start + 1, &ref, 1);
 391                 if (ref) {
 392                         node = &ref->rb_node;
 393                 } else
 394                         node = rb_first(&delayed_refs->root);
 395         }
 396 again:
 397         while (node && count < 32) {
 398                 ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 399                 if (btrfs_delayed_ref_is_head(ref)) {
 400                         head = btrfs_delayed_node_to_head(ref);
 401                         if (list_empty(&head->cluster)) {
 402                                 list_add_tail(&head->cluster, cluster);
 403                                 delayed_refs->run_delayed_start =
 404                                         head->node.bytenr;
 405                                 count++;
 406
 407                                 WARN_ON(delayed_refs->num_heads_ready == 0);
 408                                 delayed_refs->num_heads_ready--;
 409                         } else if (count) {
 410                                 /* the goal of the clustering is to find extents
 411                                  * that are likely to end up in the same extent
 412                                  * leaf on disk.  So, we don't want them spread
 413                                  * all over the tree.  Stop now if we've hit
 414                                  * a head that was already in use
 415                                  */
 416                                 break;
 417                         }
 418                 }
 419                 node = rb_next(node);
 420         }
 421         if (count) {
 422                 return 0;
 423         } else if (start) {
 424                 /*
 425                  * we've gone to the end of the rbtree without finding any
 426                  * clusters.  start from the beginning and try again
 427                  */
 428                 start = 0;
 429                 node = rb_first(&delayed_refs->root);
 430                 goto again;
 431         }
 432         return 1;
 433 }
 434
 435 void btrfs_release_ref_cluster(struct list_head *cluster)
 436 {
 437         struct list_head *pos, *q;
 438
 439         list_for_each_safe(pos, q, cluster)
 440                 list_del_init(pos);
 441 }
 442
 443 /*
 444  * helper function to update an extent delayed ref in the
 445  * rbtree.  existing and update must both have the same
 446  * bytenr and parent
 447  *
 448  * This may free existing if the update cancels out whatever
 449  * operation it was doing.
 450  */
 451 static noinline void
 452 update_existing_ref(struct btrfs_trans_handle *trans,
 453                     struct btrfs_delayed_ref_root *delayed_refs,
 454                     struct btrfs_delayed_ref_node *existing,
 455                     struct btrfs_delayed_ref_node *update)
 456 {
 457         if (update->action != existing->action) {
 458                 /*
 459                  * this is effectively undoing either an add or a
 460                  * drop.  We decrement the ref_mod, and if it goes
 461                  * down to zero we just delete the entry without
 462                  * every changing the extent allocation tree.
 463                  */
 464                 existing->ref_mod--;
 465                 if (existing->ref_mod == 0)
 466                         drop_delayed_ref(trans, delayed_refs, existing);
 467                 else
 468                         WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 469                                 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 470         } else {
 471                 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 472                         existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 473                 /*
 474                  * the action on the existing ref matches
 475                  * the action on the ref we're trying to add.
 476                  * Bump the ref_mod by one so the backref that
 477                  * is eventually added/removed has the correct
 478                  * reference count
 479                  */
 480                 existing->ref_mod += update->ref_mod;
 481         }
 482 }
 483
 484 /*
 485  * helper function to update the accounting in the head ref
 486  * existing and update must have the same bytenr
 487  */
 488 static noinline void
 489 update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
 490                          struct btrfs_delayed_ref_node *update)
 491 {
 492         struct btrfs_delayed_ref_head *existing_ref;
 493         struct btrfs_delayed_ref_head *ref;
 494
 495         existing_ref = btrfs_delayed_node_to_head(existing);
 496         ref = btrfs_delayed_node_to_head(update);
 497         BUG_ON(existing_ref->is_data != ref->is_data);
 498
 499         if (ref->must_insert_reserved) {
 500                 /* if the extent was freed and then
 501                  * reallocated before the delayed ref
 502                  * entries were processed, we can end up
 503                  * with an existing head ref without
 504                  * the must_insert_reserved flag set.
 505                  * Set it again here
 506                  */
 507                 existing_ref->must_insert_reserved = ref->must_insert_reserved;
 508
 509                 /*
 510                  * update the num_bytes so we make sure the accounting
 511                  * is done correctly
 512                  */
 513                 existing->num_bytes = update->num_bytes;
 514
 515         }
 516
 517         if (ref->extent_op) {
 518                 if (!existing_ref->extent_op) {
 519                         existing_ref->extent_op = ref->extent_op;
 520                 } else {
 521                         if (ref->extent_op->update_key) {
 522                                 memcpy(&existing_ref->extent_op->key,
 523                                        &ref->extent_op->key,
 524                                        sizeof(ref->extent_op->key));
 525                                 existing_ref->extent_op->update_key = 1;
 526                         }
 527                         if (ref->extent_op->update_flags) {
 528                                 existing_ref->extent_op->flags_to_set |=
 529                                         ref->extent_op->flags_to_set;
 530                                 existing_ref->extent_op->update_flags = 1;
 531                         }
 532                         btrfs_free_delayed_extent_op(ref->extent_op);
 533                 }
 534         }
 535         /*
 536          * update the reference mod on the head to reflect this new operation
 537          */
 538         existing->ref_mod += update->ref_mod;
 539 }
 540
 541 /*
 542  * helper function to actually insert a head node into the rbtree.
 543  * this does all the dirty work in terms of maintaining the correct
 544  * overall modification count.
 545  */
 546 static noinline void add_delayed_ref_head(struct btrfs_fs_info *fs_info,
 547                                         struct btrfs_trans_handle *trans,
 548                                         struct btrfs_delayed_ref_node *ref,
 549                                         u64 bytenr, u64 num_bytes,
 550                                         int action, int is_data)
 551 {
 552         struct btrfs_delayed_ref_node *existing;
 553         struct btrfs_delayed_ref_head *head_ref = NULL;
 554         struct btrfs_delayed_ref_root *delayed_refs;
 555         int count_mod = 1;
 556         int must_insert_reserved = 0;
 557
 558         /*
 559          * the head node stores the sum of all the mods, so dropping a ref
 560          * should drop the sum in the head node by one.
 561          */
 562         if (action == BTRFS_UPDATE_DELAYED_HEAD)
 563                 count_mod = 0;
 564         else if (action == BTRFS_DROP_DELAYED_REF)
 565                 count_mod = -1;
 566
 567         /*
 568          * BTRFS_ADD_DELAYED_EXTENT means that we need to update
 569          * the reserved accounting when the extent is finally added, or
 570          * if a later modification deletes the delayed ref without ever
 571          * inserting the extent into the extent allocation tree.
 572          * ref->must_insert_reserved is the flag used to record
 573          * that accounting mods are required.
 574          *
 575          * Once we record must_insert_reserved, switch the action to
 576          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
 577          */
 578         if (action == BTRFS_ADD_DELAYED_EXTENT)
 579                 must_insert_reserved = 1;
 580         else
 581                 must_insert_reserved = 0;
 582
 583         delayed_refs = &trans->transaction->delayed_refs;
 584
 585         /* first set the basic ref node struct up */
 586         atomic_set(&ref->refs, 1);
 587         ref->bytenr = bytenr;
 588         ref->num_bytes = num_bytes;
 589         ref->ref_mod = count_mod;
 590         ref->type  = 0;
 591         ref->action  = 0;
 592         ref->is_head = 1;
 593         ref->in_tree = 1;
 594         ref->seq = 0;
 595
 596         head_ref = btrfs_delayed_node_to_head(ref);
 597         head_ref->must_insert_reserved = must_insert_reserved;
 598         head_ref->is_data = is_data;
 599
 600         INIT_LIST_HEAD(&head_ref->cluster);
 601         mutex_init(&head_ref->mutex);
 602
 603         trace_add_delayed_ref_head(ref, head_ref, action);
 604
 605         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 606
 607         if (existing) {
 608                 update_existing_head_ref(existing, ref);
 609                 /*
 610                  * we've updated the existing ref, free the newly
 611                  * allocated ref
 612                  */
 613                 kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 614         } else {
 615                 delayed_refs->num_heads++;
 616                 delayed_refs->num_heads_ready++;
 617                 delayed_refs->num_entries++;
 618                 trans->delayed_ref_updates++;
 619         }
 620 }
 621
 622 /*
 623  * helper to insert a delayed tree ref into the rbtree.
 624  */
 625 static noinline void add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 626                                          struct btrfs_trans_handle *trans,
 627                                          struct btrfs_delayed_ref_node *ref,
 628                                          u64 bytenr, u64 num_bytes, u64 parent,
 629                                          u64 ref_root, int level, int action,
 630                                          int for_cow)
 631 {
 632         struct btrfs_delayed_ref_node *existing;
 633         struct btrfs_delayed_tree_ref *full_ref;
 634         struct btrfs_delayed_ref_root *delayed_refs;
 635         u64 seq = 0;
 636
 637         if (action == BTRFS_ADD_DELAYED_EXTENT)
 638                 action = BTRFS_ADD_DELAYED_REF;
 639
 640         delayed_refs = &trans->transaction->delayed_refs;
 641
 642         /* first set the basic ref node struct up */
 643         atomic_set(&ref->refs, 1);
 644         ref->bytenr = bytenr;
 645         ref->num_bytes = num_bytes;
 646         ref->ref_mod = 1;
 647         ref->action = action;
 648         ref->is_head = 0;
 649         ref->in_tree = 1;
 650
 651         if (need_ref_seq(for_cow, ref_root))
 652                 seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 653         ref->seq = seq;
 654
 655         full_ref = btrfs_delayed_node_to_tree_ref(ref);
 656         full_ref->parent = parent;
 657         full_ref->root = ref_root;
 658         if (parent)
 659                 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
 660         else
 661                 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
 662         full_ref->level = level;
 663
 664         trace_add_delayed_tree_ref(ref, full_ref, action);
 665
 666         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 667
 668         if (existing) {
 669                 update_existing_ref(trans, delayed_refs, existing, ref);
 670                 /*
 671                  * we've updated the existing ref, free the newly
 672                  * allocated ref
 673                  */
 674                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, full_ref);
 675         } else {
 676                 delayed_refs->num_entries++;
 677                 trans->delayed_ref_updates++;
 678         }
 679 }
 680
 681 /*
 682  * helper to insert a delayed data ref into the rbtree.
 683  */
 684 static noinline void add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 685                                          struct btrfs_trans_handle *trans,
 686                                          struct btrfs_delayed_ref_node *ref,
 687                                          u64 bytenr, u64 num_bytes, u64 parent,
 688                                          u64 ref_root, u64 owner, u64 offset,
 689                                          int action, int for_cow)
 690 {
 691         struct btrfs_delayed_ref_node *existing;
 692         struct btrfs_delayed_data_ref *full_ref;
 693         struct btrfs_delayed_ref_root *delayed_refs;
 694         u64 seq = 0;
 695
 696         if (action == BTRFS_ADD_DELAYED_EXTENT)
 697                 action = BTRFS_ADD_DELAYED_REF;
 698
 699         delayed_refs = &trans->transaction->delayed_refs;
 700
 701         /* first set the basic ref node struct up */
 702         atomic_set(&ref->refs, 1);
 703         ref->bytenr = bytenr;
 704         ref->num_bytes = num_bytes;
 705         ref->ref_mod = 1;
 706         ref->action = action;
 707         ref->is_head = 0;
 708         ref->in_tree = 1;
 709
 710         if (need_ref_seq(for_cow, ref_root))
 711                 seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 712         ref->seq = seq;
 713
 714         full_ref = btrfs_delayed_node_to_data_ref(ref);
 715         full_ref->parent = parent;
 716         full_ref->root = ref_root;
 717         if (parent)
 718                 ref->type = BTRFS_SHARED_DATA_REF_KEY;
 719         else
 720                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
 721
 722         full_ref->objectid = owner;
 723         full_ref->offset = offset;
 724
 725         trace_add_delayed_data_ref(ref, full_ref, action);
 726
 727         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 728
 729         if (existing) {
 730                 update_existing_ref(trans, delayed_refs, existing, ref);
 731                 /*
 732                  * we've updated the existing ref, free the newly
 733                  * allocated ref
 734                  */
 735                 kmem_cache_free(btrfs_delayed_data_ref_cachep, full_ref);
 736         } else {
 737                 delayed_refs->num_entries++;
 738                 trans->delayed_ref_updates++;
 739         }
 740 }
 741
 742 /*
 743  * add a delayed tree ref.  This does all of the accounting required
 744  * to make sure the delayed ref is eventually processed before this
 745  * transaction commits.
 746  */
 747 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 748                                struct btrfs_trans_handle *trans,
 749                                u64 bytenr, u64 num_bytes, u64 parent,
 750                                u64 ref_root,  int level, int action,
 751                                struct btrfs_delayed_extent_op *extent_op,
 752                                int for_cow)
 753 {
 754         struct btrfs_delayed_tree_ref *ref;
 755         struct btrfs_delayed_ref_head *head_ref;
 756         struct btrfs_delayed_ref_root *delayed_refs;
 757
 758         BUG_ON(extent_op && extent_op->is_data);
 759         ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
 760         if (!ref)
 761                 return -ENOMEM;
 762
 763         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 764         if (!head_ref) {
 765                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 766                 return -ENOMEM;
 767         }
 768
 769         head_ref->extent_op = extent_op;
 770
 771         delayed_refs = &trans->transaction->delayed_refs;
 772         spin_lock(&delayed_refs->lock);
 773
 774         /*
 775          * insert both the head node and the new ref without dropping
 776          * the spin lock
 777          */
 778         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 779                                    num_bytes, action, 0);
 780
 781         add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
 782                                    num_bytes, parent, ref_root, level, action,
 783                                    for_cow);
 784         spin_unlock(&delayed_refs->lock);
 785         if (need_ref_seq(for_cow, ref_root))
 786                 btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 787
 788         return 0;
 789 }
 790
 791 /*
 792  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 793  */
 794 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 795                                struct btrfs_trans_handle *trans,
 796                                u64 bytenr, u64 num_bytes,
 797                                u64 parent, u64 ref_root,
 798                                u64 owner, u64 offset, int action,
 799                                struct btrfs_delayed_extent_op *extent_op,
 800                                int for_cow)
 801 {
 802         struct btrfs_delayed_data_ref *ref;
 803         struct btrfs_delayed_ref_head *head_ref;
 804         struct btrfs_delayed_ref_root *delayed_refs;
 805
 806         BUG_ON(extent_op && !extent_op->is_data);
 807         ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
 808         if (!ref)
 809                 return -ENOMEM;
 810
 811         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 812         if (!head_ref) {
 813                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 814                 return -ENOMEM;
 815         }
 816
 817         head_ref->extent_op = extent_op;
 818
 819         delayed_refs = &trans->transaction->delayed_refs;
 820         spin_lock(&delayed_refs->lock);
 821
 822         /*
 823          * insert both the head node and the new ref without dropping
 824          * the spin lock
 825          */
 826         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 827                                    num_bytes, action, 1);
 828
 829         add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
 830                                    num_bytes, parent, ref_root, owner, offset,
 831                                    action, for_cow);
 832         spin_unlock(&delayed_refs->lock);
 833         if (need_ref_seq(for_cow, ref_root))
 834                 btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 835
 836         return 0;
 837 }
 838
 839 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 840                                 struct btrfs_trans_handle *trans,
 841                                 u64 bytenr, u64 num_bytes,
 842                                 struct btrfs_delayed_extent_op *extent_op)
 843 {
 844         struct btrfs_delayed_ref_head *head_ref;
 845         struct btrfs_delayed_ref_root *delayed_refs;
 846
 847         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 848         if (!head_ref)
 849                 return -ENOMEM;
 850
 851         head_ref->extent_op = extent_op;
 852
 853         delayed_refs = &trans->transaction->delayed_refs;
 854         spin_lock(&delayed_refs->lock);
 855
 856         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 857                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
 858                                    extent_op->is_data);
 859
 860         spin_unlock(&delayed_refs->lock);
 861         return 0;
 862 }
 863
 864 /*
 865  * this does a simple search for the head node for a given extent.
 866  * It must be called with the delayed ref spinlock held, and it returns
 867  * the head node if any where found, or NULL if not.
 868  */
 869 struct btrfs_delayed_ref_head *
 870 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
 871 {
 872         struct btrfs_delayed_ref_node *ref;
 873         struct btrfs_delayed_ref_root *delayed_refs;
 874
 875         delayed_refs = &trans->transaction->delayed_refs;
 876         ref = find_ref_head(&delayed_refs->root, bytenr, NULL, 0);
 877         if (ref)
 878                 return btrfs_delayed_node_to_head(ref);
 879         return NULL;
 880 }
 881
 882 void btrfs_delayed_ref_exit(void)
 883 {
 884         if (btrfs_delayed_ref_head_cachep)
 885                 kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
 886         if (btrfs_delayed_tree_ref_cachep)
 887                 kmem_cache_destroy(btrfs_delayed_tree_ref_cachep);
 888         if (btrfs_delayed_data_ref_cachep)
 889                 kmem_cache_destroy(btrfs_delayed_data_ref_cachep);
 890         if (btrfs_delayed_extent_op_cachep)
 891                 kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
 892 }
 893
 894 int btrfs_delayed_ref_init(void)
 895 {
 896         btrfs_delayed_ref_head_cachep = kmem_cache_create(
 897                                 "btrfs_delayed_ref_head",
 898                                 sizeof(struct btrfs_delayed_ref_head), 0,
 899                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 900         if (!btrfs_delayed_ref_head_cachep)
 901                 goto fail;
 902
 903         btrfs_delayed_tree_ref_cachep = kmem_cache_create(
 904                                 "btrfs_delayed_tree_ref",
 905                                 sizeof(struct btrfs_delayed_tree_ref), 0,
 906                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 907         if (!btrfs_delayed_tree_ref_cachep)
 908                 goto fail;
 909
 910         btrfs_delayed_data_ref_cachep = kmem_cache_create(
 911                                 "btrfs_delayed_data_ref",
 912                                 sizeof(struct btrfs_delayed_data_ref), 0,
 913                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 914         if (!btrfs_delayed_data_ref_cachep)
 915                 goto fail;
 916
 917         btrfs_delayed_extent_op_cachep = kmem_cache_create(
 918                                 "btrfs_delayed_extent_op",
 919                                 sizeof(struct btrfs_delayed_extent_op), 0,
 920                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 921         if (!btrfs_delayed_extent_op_cachep)
 922                 goto fail;
 923
 924         return 0;
 925 fail:
 926         btrfs_delayed_ref_exit();
 927         return -ENOMEM;
 928 }