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 /* insert a new ref to head ref rbtree */
 165 static struct btrfs_delayed_ref_head *htree_insert(struct rb_root *root,
 166                                                    struct rb_node *node)
 167 {
 168         struct rb_node **p = &root->rb_node;
 169         struct rb_node *parent_node = NULL;
 170         struct btrfs_delayed_ref_head *entry;
 171         struct btrfs_delayed_ref_head *ins;
 172         u64 bytenr;
 173
 174         ins = rb_entry(node, struct btrfs_delayed_ref_head, href_node);
 175         bytenr = ins->node.bytenr;
 176         while (*p) {
 177                 parent_node = *p;
 178                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_head,
 179                                  href_node);
 180
 181                 if (bytenr < entry->node.bytenr)
 182                         p = &(*p)->rb_left;
 183                 else if (bytenr > entry->node.bytenr)
 184                         p = &(*p)->rb_right;
 185                 else
 186                         return entry;
 187         }
 188
 189         rb_link_node(node, parent_node, p);
 190         rb_insert_color(node, root);
 191         return NULL;
 192 }
 193
 194 /*
 195  * find an head entry based on bytenr. This returns the delayed ref
 196  * head if it was able to find one, or NULL if nothing was in that spot.
 197  * If return_bigger is given, the next bigger entry is returned if no exact
 198  * match is found.
 199  */
 200 static struct btrfs_delayed_ref_head *
 201 find_ref_head(struct rb_root *root, u64 bytenr,
 202               int return_bigger)
 203 {
 204         struct rb_node *n;
 205         struct btrfs_delayed_ref_head *entry;
 206
 207         n = root->rb_node;
 208         entry = NULL;
 209         while (n) {
 210                 entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
 211
 212                 if (bytenr < entry->node.bytenr)
 213                         n = n->rb_left;
 214                 else if (bytenr > entry->node.bytenr)
 215                         n = n->rb_right;
 216                 else
 217                         return entry;
 218         }
 219         if (entry && return_bigger) {
 220                 if (bytenr > entry->node.bytenr) {
 221                         n = rb_next(&entry->href_node);
 222                         if (!n)
 223                                 n = rb_first(root);
 224                         entry = rb_entry(n, struct btrfs_delayed_ref_head,
 225                                          href_node);
 226                         return entry;
 227                 }
 228                 return entry;
 229         }
 230         return NULL;
 231 }
 232
 233 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 234                            struct btrfs_delayed_ref_head *head)
 235 {
 236         struct btrfs_delayed_ref_root *delayed_refs;
 237
 238         delayed_refs = &trans->transaction->delayed_refs;
 239         assert_spin_locked(&delayed_refs->lock);
 240         if (mutex_trylock(&head->mutex))
 241                 return 0;
 242
 243         atomic_inc(&head->node.refs);
 244         spin_unlock(&delayed_refs->lock);
 245
 246         mutex_lock(&head->mutex);
 247         spin_lock(&delayed_refs->lock);
 248         if (!head->node.in_tree) {
 249                 mutex_unlock(&head->mutex);
 250                 btrfs_put_delayed_ref(&head->node);
 251                 return -EAGAIN;
 252         }
 253         btrfs_put_delayed_ref(&head->node);
 254         return 0;
 255 }
 256
 257 static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
 258                                     struct btrfs_delayed_ref_root *delayed_refs,
 259                                     struct btrfs_delayed_ref_head *head,
 260                                     struct btrfs_delayed_ref_node *ref)
 261 {
 262         if (btrfs_delayed_ref_is_head(ref)) {
 263                 head = btrfs_delayed_node_to_head(ref);
 264                 rb_erase(&head->href_node, &delayed_refs->href_root);
 265         } else {
 266                 assert_spin_locked(&head->lock);
 267                 rb_erase(&ref->rb_node, &head->ref_root);
 268         }
 269         ref->in_tree = 0;
 270         btrfs_put_delayed_ref(ref);
 271         atomic_dec(&delayed_refs->num_entries);
 272         if (trans->delayed_ref_updates)
 273                 trans->delayed_ref_updates--;
 274 }
 275
 276 static int merge_ref(struct btrfs_trans_handle *trans,
 277                      struct btrfs_delayed_ref_root *delayed_refs,
 278                      struct btrfs_delayed_ref_head *head,
 279                      struct btrfs_delayed_ref_node *ref, u64 seq)
 280 {
 281         struct rb_node *node;
 282         int mod = 0;
 283         int done = 0;
 284
 285         node = rb_next(&ref->rb_node);
 286         while (!done && node) {
 287                 struct btrfs_delayed_ref_node *next;
 288
 289                 next = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 290                 node = rb_next(node);
 291                 if (seq && next->seq >= seq)
 292                         break;
 293                 if (comp_entry(ref, next, 0))
 294                         continue;
 295
 296                 if (ref->action == next->action) {
 297                         mod = next->ref_mod;
 298                 } else {
 299                         if (ref->ref_mod < next->ref_mod) {
 300                                 struct btrfs_delayed_ref_node *tmp;
 301
 302                                 tmp = ref;
 303                                 ref = next;
 304                                 next = tmp;
 305                                 done = 1;
 306                         }
 307                         mod = -next->ref_mod;
 308                 }
 309
 310                 drop_delayed_ref(trans, delayed_refs, head, next);
 311                 ref->ref_mod += mod;
 312                 if (ref->ref_mod == 0) {
 313                         drop_delayed_ref(trans, delayed_refs, head, ref);
 314                         done = 1;
 315                 } else {
 316                         /*
 317                          * You can't have multiples of the same ref on a tree
 318                          * block.
 319                          */
 320                         WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
 321                                 ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
 322                 }
 323         }
 324         return done;
 325 }
 326
 327 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 328                               struct btrfs_fs_info *fs_info,
 329                               struct btrfs_delayed_ref_root *delayed_refs,
 330                               struct btrfs_delayed_ref_head *head)
 331 {
 332         struct rb_node *node;
 333         u64 seq = 0;
 334
 335         assert_spin_locked(&head->lock);
 336         /*
 337          * We don't have too much refs to merge in the case of delayed data
 338          * refs.
 339          */
 340         if (head->is_data)
 341                 return;
 342
 343         spin_lock(&fs_info->tree_mod_seq_lock);
 344         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 345                 struct seq_list *elem;
 346
 347                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 348                                         struct seq_list, list);
 349                 seq = elem->seq;
 350         }
 351         spin_unlock(&fs_info->tree_mod_seq_lock);
 352
 353         node = rb_first(&head->ref_root);
 354         while (node) {
 355                 struct btrfs_delayed_ref_node *ref;
 356
 357                 ref = rb_entry(node, struct btrfs_delayed_ref_node,
 358                                rb_node);
 359                 /* We can't merge refs that are outside of our seq count */
 360                 if (seq && ref->seq >= seq)
 361                         break;
 362                 if (merge_ref(trans, delayed_refs, head, ref, seq))
 363                         node = rb_first(&head->ref_root);
 364                 else
 365                         node = rb_next(&ref->rb_node);
 366         }
 367 }
 368
 369 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 370                             struct btrfs_delayed_ref_root *delayed_refs,
 371                             u64 seq)
 372 {
 373         struct seq_list *elem;
 374         int ret = 0;
 375
 376         spin_lock(&fs_info->tree_mod_seq_lock);
 377         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 378                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 379                                         struct seq_list, list);
 380                 if (seq >= elem->seq) {
 381                         pr_debug("holding back delayed_ref %#x.%x, lowest is %#x.%x (%p)\n",
 382                                  (u32)(seq >> 32), (u32)seq,
 383                                  (u32)(elem->seq >> 32), (u32)elem->seq,
 384                                  delayed_refs);
 385                         ret = 1;
 386                 }
 387         }
 388
 389         spin_unlock(&fs_info->tree_mod_seq_lock);
 390         return ret;
 391 }
 392
 393 struct btrfs_delayed_ref_head *
 394 btrfs_select_ref_head(struct btrfs_trans_handle *trans)
 395 {
 396         struct btrfs_delayed_ref_root *delayed_refs;
 397         struct btrfs_delayed_ref_head *head;
 398         u64 start;
 399         bool loop = false;
 400
 401         delayed_refs = &trans->transaction->delayed_refs;
 402
 403 again:
 404         start = delayed_refs->run_delayed_start;
 405         head = find_ref_head(&delayed_refs->href_root, start, 1);
 406         if (!head && !loop) {
 407                 delayed_refs->run_delayed_start = 0;
 408                 start = 0;
 409                 loop = true;
 410                 head = find_ref_head(&delayed_refs->href_root, start, 1);
 411                 if (!head)
 412                         return NULL;
 413         } else if (!head && loop) {
 414                 return NULL;
 415         }
 416
 417         while (head->processing) {
 418                 struct rb_node *node;
 419
 420                 node = rb_next(&head->href_node);
 421                 if (!node) {
 422                         if (loop)
 423                                 return NULL;
 424                         delayed_refs->run_delayed_start = 0;
 425                         start = 0;
 426                         loop = true;
 427                         goto again;
 428                 }
 429                 head = rb_entry(node, struct btrfs_delayed_ref_head,
 430                                 href_node);
 431         }
 432
 433         head->processing = 1;
 434         WARN_ON(delayed_refs->num_heads_ready == 0);
 435         delayed_refs->num_heads_ready--;
 436         delayed_refs->run_delayed_start = head->node.bytenr +
 437                 head->node.num_bytes;
 438         return head;
 439 }
 440
 441 /*
 442  * helper function to update an extent delayed ref in the
 443  * rbtree.  existing and update must both have the same
 444  * bytenr and parent
 445  *
 446  * This may free existing if the update cancels out whatever
 447  * operation it was doing.
 448  */
 449 static noinline void
 450 update_existing_ref(struct btrfs_trans_handle *trans,
 451                     struct btrfs_delayed_ref_root *delayed_refs,
 452                     struct btrfs_delayed_ref_head *head,
 453                     struct btrfs_delayed_ref_node *existing,
 454                     struct btrfs_delayed_ref_node *update)
 455 {
 456         if (update->action != existing->action) {
 457                 /*
 458                  * this is effectively undoing either an add or a
 459                  * drop.  We decrement the ref_mod, and if it goes
 460                  * down to zero we just delete the entry without
 461                  * every changing the extent allocation tree.
 462                  */
 463                 existing->ref_mod--;
 464                 if (existing->ref_mod == 0)
 465                         drop_delayed_ref(trans, delayed_refs, head, existing);
 466                 else
 467                         WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 468                                 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 469         } else {
 470                 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 471                         existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 472                 /*
 473                  * the action on the existing ref matches
 474                  * the action on the ref we're trying to add.
 475                  * Bump the ref_mod by one so the backref that
 476                  * is eventually added/removed has the correct
 477                  * reference count
 478                  */
 479                 existing->ref_mod += update->ref_mod;
 480         }
 481 }
 482
 483 /*
 484  * helper function to update the accounting in the head ref
 485  * existing and update must have the same bytenr
 486  */
 487 static noinline void
 488 update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
 489                          struct btrfs_delayed_ref_node *update)
 490 {
 491         struct btrfs_delayed_ref_head *existing_ref;
 492         struct btrfs_delayed_ref_head *ref;
 493
 494         existing_ref = btrfs_delayed_node_to_head(existing);
 495         ref = btrfs_delayed_node_to_head(update);
 496         BUG_ON(existing_ref->is_data != ref->is_data);
 497
 498         spin_lock(&existing_ref->lock);
 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          * only need the lock for this case cause we could be processing it
 538          * currently, for refs we just added we know we're a-ok.
 539          */
 540         existing->ref_mod += update->ref_mod;
 541         spin_unlock(&existing_ref->lock);
 542 }
 543
 544 /*
 545  * helper function to actually insert a head node into the rbtree.
 546  * this does all the dirty work in terms of maintaining the correct
 547  * overall modification count.
 548  */
 549 static noinline struct btrfs_delayed_ref_head *
 550 add_delayed_ref_head(struct btrfs_fs_info *fs_info,
 551                      struct btrfs_trans_handle *trans,
 552                      struct btrfs_delayed_ref_node *ref, u64 bytenr,
 553                      u64 num_bytes, int action, int is_data)
 554 {
 555         struct btrfs_delayed_ref_head *existing;
 556         struct btrfs_delayed_ref_head *head_ref = NULL;
 557         struct btrfs_delayed_ref_root *delayed_refs;
 558         int count_mod = 1;
 559         int must_insert_reserved = 0;
 560
 561         /*
 562          * the head node stores the sum of all the mods, so dropping a ref
 563          * should drop the sum in the head node by one.
 564          */
 565         if (action == BTRFS_UPDATE_DELAYED_HEAD)
 566                 count_mod = 0;
 567         else if (action == BTRFS_DROP_DELAYED_REF)
 568                 count_mod = -1;
 569
 570         /*
 571          * BTRFS_ADD_DELAYED_EXTENT means that we need to update
 572          * the reserved accounting when the extent is finally added, or
 573          * if a later modification deletes the delayed ref without ever
 574          * inserting the extent into the extent allocation tree.
 575          * ref->must_insert_reserved is the flag used to record
 576          * that accounting mods are required.
 577          *
 578          * Once we record must_insert_reserved, switch the action to
 579          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
 580          */
 581         if (action == BTRFS_ADD_DELAYED_EXTENT)
 582                 must_insert_reserved = 1;
 583         else
 584                 must_insert_reserved = 0;
 585
 586         delayed_refs = &trans->transaction->delayed_refs;
 587
 588         /* first set the basic ref node struct up */
 589         atomic_set(&ref->refs, 1);
 590         ref->bytenr = bytenr;
 591         ref->num_bytes = num_bytes;
 592         ref->ref_mod = count_mod;
 593         ref->type  = 0;
 594         ref->action  = 0;
 595         ref->is_head = 1;
 596         ref->in_tree = 1;
 597         ref->seq = 0;
 598
 599         head_ref = btrfs_delayed_node_to_head(ref);
 600         head_ref->must_insert_reserved = must_insert_reserved;
 601         head_ref->is_data = is_data;
 602         head_ref->ref_root = RB_ROOT;
 603         head_ref->processing = 0;
 604
 605         spin_lock_init(&head_ref->lock);
 606         mutex_init(&head_ref->mutex);
 607
 608         trace_add_delayed_ref_head(ref, head_ref, action);
 609
 610         existing = htree_insert(&delayed_refs->href_root,
 611                                 &head_ref->href_node);
 612         if (existing) {
 613                 update_existing_head_ref(&existing->node, ref);
 614                 /*
 615                  * we've updated the existing ref, free the newly
 616                  * allocated ref
 617                  */
 618                 kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 619                 head_ref = existing;
 620         } else {
 621                 delayed_refs->num_heads++;
 622                 delayed_refs->num_heads_ready++;
 623                 atomic_inc(&delayed_refs->num_entries);
 624                 trans->delayed_ref_updates++;
 625         }
 626         return head_ref;
 627 }
 628
 629 /*
 630  * helper to insert a delayed tree ref into the rbtree.
 631  */
 632 static noinline void
 633 add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 634                      struct btrfs_trans_handle *trans,
 635                      struct btrfs_delayed_ref_head *head_ref,
 636                      struct btrfs_delayed_ref_node *ref, u64 bytenr,
 637                      u64 num_bytes, u64 parent, u64 ref_root, int level,
 638                      int action, int for_cow)
 639 {
 640         struct btrfs_delayed_ref_node *existing;
 641         struct btrfs_delayed_tree_ref *full_ref;
 642         struct btrfs_delayed_ref_root *delayed_refs;
 643         u64 seq = 0;
 644
 645         if (action == BTRFS_ADD_DELAYED_EXTENT)
 646                 action = BTRFS_ADD_DELAYED_REF;
 647
 648         delayed_refs = &trans->transaction->delayed_refs;
 649
 650         /* first set the basic ref node struct up */
 651         atomic_set(&ref->refs, 1);
 652         ref->bytenr = bytenr;
 653         ref->num_bytes = num_bytes;
 654         ref->ref_mod = 1;
 655         ref->action = action;
 656         ref->is_head = 0;
 657         ref->in_tree = 1;
 658
 659         if (need_ref_seq(for_cow, ref_root))
 660                 seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 661         ref->seq = seq;
 662
 663         full_ref = btrfs_delayed_node_to_tree_ref(ref);
 664         full_ref->parent = parent;
 665         full_ref->root = ref_root;
 666         if (parent)
 667                 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
 668         else
 669                 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
 670         full_ref->level = level;
 671
 672         trace_add_delayed_tree_ref(ref, full_ref, action);
 673
 674         spin_lock(&head_ref->lock);
 675         existing = tree_insert(&head_ref->ref_root, &ref->rb_node);
 676         if (existing) {
 677                 update_existing_ref(trans, delayed_refs, head_ref, existing,
 678                                     ref);
 679                 /*
 680                  * we've updated the existing ref, free the newly
 681                  * allocated ref
 682                  */
 683                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, full_ref);
 684         } else {
 685                 atomic_inc(&delayed_refs->num_entries);
 686                 trans->delayed_ref_updates++;
 687         }
 688         spin_unlock(&head_ref->lock);
 689 }
 690
 691 /*
 692  * helper to insert a delayed data ref into the rbtree.
 693  */
 694 static noinline void
 695 add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 696                      struct btrfs_trans_handle *trans,
 697                      struct btrfs_delayed_ref_head *head_ref,
 698                      struct btrfs_delayed_ref_node *ref, u64 bytenr,
 699                      u64 num_bytes, u64 parent, u64 ref_root, u64 owner,
 700                      u64 offset, int action, int for_cow)
 701 {
 702         struct btrfs_delayed_ref_node *existing;
 703         struct btrfs_delayed_data_ref *full_ref;
 704         struct btrfs_delayed_ref_root *delayed_refs;
 705         u64 seq = 0;
 706
 707         if (action == BTRFS_ADD_DELAYED_EXTENT)
 708                 action = BTRFS_ADD_DELAYED_REF;
 709
 710         delayed_refs = &trans->transaction->delayed_refs;
 711
 712         /* first set the basic ref node struct up */
 713         atomic_set(&ref->refs, 1);
 714         ref->bytenr = bytenr;
 715         ref->num_bytes = num_bytes;
 716         ref->ref_mod = 1;
 717         ref->action = action;
 718         ref->is_head = 0;
 719         ref->in_tree = 1;
 720
 721         if (need_ref_seq(for_cow, ref_root))
 722                 seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 723         ref->seq = seq;
 724
 725         full_ref = btrfs_delayed_node_to_data_ref(ref);
 726         full_ref->parent = parent;
 727         full_ref->root = ref_root;
 728         if (parent)
 729                 ref->type = BTRFS_SHARED_DATA_REF_KEY;
 730         else
 731                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
 732
 733         full_ref->objectid = owner;
 734         full_ref->offset = offset;
 735
 736         trace_add_delayed_data_ref(ref, full_ref, action);
 737
 738         spin_lock(&head_ref->lock);
 739         existing = tree_insert(&head_ref->ref_root, &ref->rb_node);
 740         if (existing) {
 741                 update_existing_ref(trans, delayed_refs, head_ref, existing,
 742                                     ref);
 743                 /*
 744                  * we've updated the existing ref, free the newly
 745                  * allocated ref
 746                  */
 747                 kmem_cache_free(btrfs_delayed_data_ref_cachep, full_ref);
 748         } else {
 749                 atomic_inc(&delayed_refs->num_entries);
 750                 trans->delayed_ref_updates++;
 751         }
 752         spin_unlock(&head_ref->lock);
 753 }
 754
 755 /*
 756  * add a delayed tree ref.  This does all of the accounting required
 757  * to make sure the delayed ref is eventually processed before this
 758  * transaction commits.
 759  */
 760 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 761                                struct btrfs_trans_handle *trans,
 762                                u64 bytenr, u64 num_bytes, u64 parent,
 763                                u64 ref_root,  int level, int action,
 764                                struct btrfs_delayed_extent_op *extent_op,
 765                                int for_cow)
 766 {
 767         struct btrfs_delayed_tree_ref *ref;
 768         struct btrfs_delayed_ref_head *head_ref;
 769         struct btrfs_delayed_ref_root *delayed_refs;
 770
 771         BUG_ON(extent_op && extent_op->is_data);
 772         ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
 773         if (!ref)
 774                 return -ENOMEM;
 775
 776         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 777         if (!head_ref) {
 778                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 779                 return -ENOMEM;
 780         }
 781
 782         head_ref->extent_op = extent_op;
 783
 784         delayed_refs = &trans->transaction->delayed_refs;
 785         spin_lock(&delayed_refs->lock);
 786
 787         /*
 788          * insert both the head node and the new ref without dropping
 789          * the spin lock
 790          */
 791         head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node,
 792                                         bytenr, num_bytes, action, 0);
 793
 794         add_delayed_tree_ref(fs_info, trans, head_ref, &ref->node, bytenr,
 795                                    num_bytes, parent, ref_root, level, action,
 796                                    for_cow);
 797         spin_unlock(&delayed_refs->lock);
 798         if (need_ref_seq(for_cow, ref_root))
 799                 btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 800
 801         return 0;
 802 }
 803
 804 /*
 805  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 806  */
 807 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 808                                struct btrfs_trans_handle *trans,
 809                                u64 bytenr, u64 num_bytes,
 810                                u64 parent, u64 ref_root,
 811                                u64 owner, u64 offset, int action,
 812                                struct btrfs_delayed_extent_op *extent_op,
 813                                int for_cow)
 814 {
 815         struct btrfs_delayed_data_ref *ref;
 816         struct btrfs_delayed_ref_head *head_ref;
 817         struct btrfs_delayed_ref_root *delayed_refs;
 818
 819         BUG_ON(extent_op && !extent_op->is_data);
 820         ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
 821         if (!ref)
 822                 return -ENOMEM;
 823
 824         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 825         if (!head_ref) {
 826                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 827                 return -ENOMEM;
 828         }
 829
 830         head_ref->extent_op = extent_op;
 831
 832         delayed_refs = &trans->transaction->delayed_refs;
 833         spin_lock(&delayed_refs->lock);
 834
 835         /*
 836          * insert both the head node and the new ref without dropping
 837          * the spin lock
 838          */
 839         head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node,
 840                                         bytenr, num_bytes, action, 1);
 841
 842         add_delayed_data_ref(fs_info, trans, head_ref, &ref->node, bytenr,
 843                                    num_bytes, parent, ref_root, owner, offset,
 844                                    action, for_cow);
 845         spin_unlock(&delayed_refs->lock);
 846         if (need_ref_seq(for_cow, ref_root))
 847                 btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 848
 849         return 0;
 850 }
 851
 852 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 853                                 struct btrfs_trans_handle *trans,
 854                                 u64 bytenr, u64 num_bytes,
 855                                 struct btrfs_delayed_extent_op *extent_op)
 856 {
 857         struct btrfs_delayed_ref_head *head_ref;
 858         struct btrfs_delayed_ref_root *delayed_refs;
 859
 860         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 861         if (!head_ref)
 862                 return -ENOMEM;
 863
 864         head_ref->extent_op = extent_op;
 865
 866         delayed_refs = &trans->transaction->delayed_refs;
 867         spin_lock(&delayed_refs->lock);
 868
 869         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 870                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
 871                                    extent_op->is_data);
 872
 873         spin_unlock(&delayed_refs->lock);
 874         return 0;
 875 }
 876
 877 /*
 878  * this does a simple search for the head node for a given extent.
 879  * It must be called with the delayed ref spinlock held, and it returns
 880  * the head node if any where found, or NULL if not.
 881  */
 882 struct btrfs_delayed_ref_head *
 883 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
 884 {
 885         struct btrfs_delayed_ref_root *delayed_refs;
 886
 887         delayed_refs = &trans->transaction->delayed_refs;
 888         return find_ref_head(&delayed_refs->href_root, bytenr, 0);
 889 }
 890
 891 void btrfs_delayed_ref_exit(void)
 892 {
 893         if (btrfs_delayed_ref_head_cachep)
 894                 kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
 895         if (btrfs_delayed_tree_ref_cachep)
 896                 kmem_cache_destroy(btrfs_delayed_tree_ref_cachep);
 897         if (btrfs_delayed_data_ref_cachep)
 898                 kmem_cache_destroy(btrfs_delayed_data_ref_cachep);
 899         if (btrfs_delayed_extent_op_cachep)
 900                 kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
 901 }
 902
 903 int btrfs_delayed_ref_init(void)
 904 {
 905         btrfs_delayed_ref_head_cachep = kmem_cache_create(
 906                                 "btrfs_delayed_ref_head",
 907                                 sizeof(struct btrfs_delayed_ref_head), 0,
 908                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 909         if (!btrfs_delayed_ref_head_cachep)
 910                 goto fail;
 911
 912         btrfs_delayed_tree_ref_cachep = kmem_cache_create(
 913                                 "btrfs_delayed_tree_ref",
 914                                 sizeof(struct btrfs_delayed_tree_ref), 0,
 915                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 916         if (!btrfs_delayed_tree_ref_cachep)
 917                 goto fail;
 918
 919         btrfs_delayed_data_ref_cachep = kmem_cache_create(
 920                                 "btrfs_delayed_data_ref",
 921                                 sizeof(struct btrfs_delayed_data_ref), 0,
 922                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 923         if (!btrfs_delayed_data_ref_cachep)
 924                 goto fail;
 925
 926         btrfs_delayed_extent_op_cachep = kmem_cache_create(
 927                                 "btrfs_delayed_extent_op",
 928                                 sizeof(struct btrfs_delayed_extent_op), 0,
 929                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 930         if (!btrfs_delayed_extent_op_cachep)
 931                 goto fail;
 932
 933         return 0;
 934 fail:
 935         btrfs_delayed_ref_exit();
 936         return -ENOMEM;
 937 }