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