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 update an extent delayed ref in the
 323  * rbtree.  existing and update must both have the same
 324  * bytenr and parent
 325  *
 326  * This may free existing if the update cancels out whatever
 327  * operation it was doing.
 328  */
 329 static noinline void
 330 update_existing_ref(struct btrfs_trans_handle *trans,
 331                     struct btrfs_delayed_ref_root *delayed_refs,
 332                     struct btrfs_delayed_ref_node *existing,
 333                     struct btrfs_delayed_ref_node *update)
 334 {
 335         if (update->action != existing->action) {
 336                 /*
 337                  * this is effectively undoing either an add or a
 338                  * drop.  We decrement the ref_mod, and if it goes
 339                  * down to zero we just delete the entry without
 340                  * every changing the extent allocation tree.
 341                  */
 342                 existing->ref_mod--;
 343                 if (existing->ref_mod == 0) {
 344                         rb_erase(&existing->rb_node,
 345                                  &delayed_refs->root);
 346                         existing->in_tree = 0;
 347                         btrfs_put_delayed_ref(existing);
 348                         delayed_refs->num_entries--;
 349                         if (trans->delayed_ref_updates)
 350                                 trans->delayed_ref_updates--;
 351                 } else {
 352                         WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 353                                 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 354                 }
 355         } else {
 356                 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 357                         existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 358                 /*
 359                  * the action on the existing ref matches
 360                  * the action on the ref we're trying to add.
 361                  * Bump the ref_mod by one so the backref that
 362                  * is eventually added/removed has the correct
 363                  * reference count
 364                  */
 365                 existing->ref_mod += update->ref_mod;
 366         }
 367 }
 368
 369 /*
 370  * helper function to update the accounting in the head ref
 371  * existing and update must have the same bytenr
 372  */
 373 static noinline void
 374 update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
 375                          struct btrfs_delayed_ref_node *update)
 376 {
 377         struct btrfs_delayed_ref_head *existing_ref;
 378         struct btrfs_delayed_ref_head *ref;
 379
 380         existing_ref = btrfs_delayed_node_to_head(existing);
 381         ref = btrfs_delayed_node_to_head(update);
 382         BUG_ON(existing_ref->is_data != ref->is_data);
 383
 384         if (ref->must_insert_reserved) {
 385                 /* if the extent was freed and then
 386                  * reallocated before the delayed ref
 387                  * entries were processed, we can end up
 388                  * with an existing head ref without
 389                  * the must_insert_reserved flag set.
 390                  * Set it again here
 391                  */
 392                 existing_ref->must_insert_reserved = ref->must_insert_reserved;
 393
 394                 /*
 395                  * update the num_bytes so we make sure the accounting
 396                  * is done correctly
 397                  */
 398                 existing->num_bytes = update->num_bytes;
 399
 400         }
 401
 402         if (ref->extent_op) {
 403                 if (!existing_ref->extent_op) {
 404                         existing_ref->extent_op = ref->extent_op;
 405                 } else {
 406                         if (ref->extent_op->update_key) {
 407                                 memcpy(&existing_ref->extent_op->key,
 408                                        &ref->extent_op->key,
 409                                        sizeof(ref->extent_op->key));
 410                                 existing_ref->extent_op->update_key = 1;
 411                         }
 412                         if (ref->extent_op->update_flags) {
 413                                 existing_ref->extent_op->flags_to_set |=
 414                                         ref->extent_op->flags_to_set;
 415                                 existing_ref->extent_op->update_flags = 1;
 416                         }
 417                         kfree(ref->extent_op);
 418                 }
 419         }
 420         /*
 421          * update the reference mod on the head to reflect this new operation
 422          */
 423         existing->ref_mod += update->ref_mod;
 424 }
 425
 426 /*
 427  * helper function to actually insert a head node into the rbtree.
 428  * this does all the dirty work in terms of maintaining the correct
 429  * overall modification count.
 430  */
 431 static noinline int add_delayed_ref_head(struct btrfs_trans_handle *trans,
 432                                         struct btrfs_delayed_ref_node *ref,
 433                                         u64 bytenr, u64 num_bytes,
 434                                         int action, int is_data)
 435 {
 436         struct btrfs_delayed_ref_node *existing;
 437         struct btrfs_delayed_ref_head *head_ref = NULL;
 438         struct btrfs_delayed_ref_root *delayed_refs;
 439         int count_mod = 1;
 440         int must_insert_reserved = 0;
 441
 442         /*
 443          * the head node stores the sum of all the mods, so dropping a ref
 444          * should drop the sum in the head node by one.
 445          */
 446         if (action == BTRFS_UPDATE_DELAYED_HEAD)
 447                 count_mod = 0;
 448         else if (action == BTRFS_DROP_DELAYED_REF)
 449                 count_mod = -1;
 450
 451         /*
 452          * BTRFS_ADD_DELAYED_EXTENT means that we need to update
 453          * the reserved accounting when the extent is finally added, or
 454          * if a later modification deletes the delayed ref without ever
 455          * inserting the extent into the extent allocation tree.
 456          * ref->must_insert_reserved is the flag used to record
 457          * that accounting mods are required.
 458          *
 459          * Once we record must_insert_reserved, switch the action to
 460          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
 461          */
 462         if (action == BTRFS_ADD_DELAYED_EXTENT)
 463                 must_insert_reserved = 1;
 464         else
 465                 must_insert_reserved = 0;
 466
 467         delayed_refs = &trans->transaction->delayed_refs;
 468
 469         /* first set the basic ref node struct up */
 470         atomic_set(&ref->refs, 1);
 471         ref->bytenr = bytenr;
 472         ref->num_bytes = num_bytes;
 473         ref->ref_mod = count_mod;
 474         ref->type  = 0;
 475         ref->action  = 0;
 476         ref->is_head = 1;
 477         ref->in_tree = 1;
 478
 479         head_ref = btrfs_delayed_node_to_head(ref);
 480         head_ref->must_insert_reserved = must_insert_reserved;
 481         head_ref->is_data = is_data;
 482
 483         INIT_LIST_HEAD(&head_ref->cluster);
 484         mutex_init(&head_ref->mutex);
 485
 486         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 487
 488         if (existing) {
 489                 update_existing_head_ref(existing, ref);
 490                 /*
 491                  * we've updated the existing ref, free the newly
 492                  * allocated ref
 493                  */
 494                 kfree(ref);
 495         } else {
 496                 delayed_refs->num_heads++;
 497                 delayed_refs->num_heads_ready++;
 498                 delayed_refs->num_entries++;
 499                 trans->delayed_ref_updates++;
 500         }
 501         return 0;
 502 }
 503
 504 /*
 505  * helper to insert a delayed tree ref into the rbtree.
 506  */
 507 static noinline int add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 508                                          struct btrfs_delayed_ref_node *ref,
 509                                          u64 bytenr, u64 num_bytes, u64 parent,
 510                                          u64 ref_root, int level, int action)
 511 {
 512         struct btrfs_delayed_ref_node *existing;
 513         struct btrfs_delayed_tree_ref *full_ref;
 514         struct btrfs_delayed_ref_root *delayed_refs;
 515
 516         if (action == BTRFS_ADD_DELAYED_EXTENT)
 517                 action = BTRFS_ADD_DELAYED_REF;
 518
 519         delayed_refs = &trans->transaction->delayed_refs;
 520
 521         /* first set the basic ref node struct up */
 522         atomic_set(&ref->refs, 1);
 523         ref->bytenr = bytenr;
 524         ref->num_bytes = num_bytes;
 525         ref->ref_mod = 1;
 526         ref->action = action;
 527         ref->is_head = 0;
 528         ref->in_tree = 1;
 529
 530         full_ref = btrfs_delayed_node_to_tree_ref(ref);
 531         if (parent) {
 532                 full_ref->parent = parent;
 533                 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
 534         } else {
 535                 full_ref->root = ref_root;
 536                 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
 537         }
 538         full_ref->level = level;
 539
 540         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 541
 542         if (existing) {
 543                 update_existing_ref(trans, delayed_refs, existing, ref);
 544                 /*
 545                  * we've updated the existing ref, free the newly
 546                  * allocated ref
 547                  */
 548                 kfree(ref);
 549         } else {
 550                 delayed_refs->num_entries++;
 551                 trans->delayed_ref_updates++;
 552         }
 553         return 0;
 554 }
 555
 556 /*
 557  * helper to insert a delayed data ref into the rbtree.
 558  */
 559 static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans,
 560                                          struct btrfs_delayed_ref_node *ref,
 561                                          u64 bytenr, u64 num_bytes, u64 parent,
 562                                          u64 ref_root, u64 owner, u64 offset,
 563                                          int action)
 564 {
 565         struct btrfs_delayed_ref_node *existing;
 566         struct btrfs_delayed_data_ref *full_ref;
 567         struct btrfs_delayed_ref_root *delayed_refs;
 568
 569         if (action == BTRFS_ADD_DELAYED_EXTENT)
 570                 action = BTRFS_ADD_DELAYED_REF;
 571
 572         delayed_refs = &trans->transaction->delayed_refs;
 573
 574         /* first set the basic ref node struct up */
 575         atomic_set(&ref->refs, 1);
 576         ref->bytenr = bytenr;
 577         ref->num_bytes = num_bytes;
 578         ref->ref_mod = 1;
 579         ref->action = action;
 580         ref->is_head = 0;
 581         ref->in_tree = 1;
 582
 583         full_ref = btrfs_delayed_node_to_data_ref(ref);
 584         if (parent) {
 585                 full_ref->parent = parent;
 586                 ref->type = BTRFS_SHARED_DATA_REF_KEY;
 587         } else {
 588                 full_ref->root = ref_root;
 589                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
 590         }
 591         full_ref->objectid = owner;
 592         full_ref->offset = offset;
 593
 594         existing = tree_insert(&delayed_refs->root, &ref->rb_node);
 595
 596         if (existing) {
 597                 update_existing_ref(trans, delayed_refs, existing, ref);
 598                 /*
 599                  * we've updated the existing ref, free the newly
 600                  * allocated ref
 601                  */
 602                 kfree(ref);
 603         } else {
 604                 delayed_refs->num_entries++;
 605                 trans->delayed_ref_updates++;
 606         }
 607         return 0;
 608 }
 609
 610 /*
 611  * add a delayed tree ref.  This does all of the accounting required
 612  * to make sure the delayed ref is eventually processed before this
 613  * transaction commits.
 614  */
 615 int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 616                                u64 bytenr, u64 num_bytes, u64 parent,
 617                                u64 ref_root,  int level, int action,
 618                                struct btrfs_delayed_extent_op *extent_op)
 619 {
 620         struct btrfs_delayed_tree_ref *ref;
 621         struct btrfs_delayed_ref_head *head_ref;
 622         struct btrfs_delayed_ref_root *delayed_refs;
 623         int ret;
 624
 625         BUG_ON(extent_op && extent_op->is_data);
 626         ref = kmalloc(sizeof(*ref), GFP_NOFS);
 627         if (!ref)
 628                 return -ENOMEM;
 629
 630         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
 631         if (!head_ref) {
 632                 kfree(ref);
 633                 return -ENOMEM;
 634         }
 635
 636         head_ref->extent_op = extent_op;
 637
 638         delayed_refs = &trans->transaction->delayed_refs;
 639         spin_lock(&delayed_refs->lock);
 640
 641         /*
 642          * insert both the head node and the new ref without dropping
 643          * the spin lock
 644          */
 645         ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
 646                                    action, 0);
 647         BUG_ON(ret);
 648
 649         ret = add_delayed_tree_ref(trans, &ref->node, bytenr, num_bytes,
 650                                    parent, ref_root, level, action);
 651         BUG_ON(ret);
 652         spin_unlock(&delayed_refs->lock);
 653         return 0;
 654 }
 655
 656 /*
 657  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 658  */
 659 int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 660                                u64 bytenr, u64 num_bytes,
 661                                u64 parent, u64 ref_root,
 662                                u64 owner, u64 offset, int action,
 663                                struct btrfs_delayed_extent_op *extent_op)
 664 {
 665         struct btrfs_delayed_data_ref *ref;
 666         struct btrfs_delayed_ref_head *head_ref;
 667         struct btrfs_delayed_ref_root *delayed_refs;
 668         int ret;
 669
 670         BUG_ON(extent_op && !extent_op->is_data);
 671         ref = kmalloc(sizeof(*ref), GFP_NOFS);
 672         if (!ref)
 673                 return -ENOMEM;
 674
 675         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
 676         if (!head_ref) {
 677                 kfree(ref);
 678                 return -ENOMEM;
 679         }
 680
 681         head_ref->extent_op = extent_op;
 682
 683         delayed_refs = &trans->transaction->delayed_refs;
 684         spin_lock(&delayed_refs->lock);
 685
 686         /*
 687          * insert both the head node and the new ref without dropping
 688          * the spin lock
 689          */
 690         ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
 691                                    action, 1);
 692         BUG_ON(ret);
 693
 694         ret = add_delayed_data_ref(trans, &ref->node, bytenr, num_bytes,
 695                                    parent, ref_root, owner, offset, action);
 696         BUG_ON(ret);
 697         spin_unlock(&delayed_refs->lock);
 698         return 0;
 699 }
 700
 701 int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
 702                                 u64 bytenr, u64 num_bytes,
 703                                 struct btrfs_delayed_extent_op *extent_op)
 704 {
 705         struct btrfs_delayed_ref_head *head_ref;
 706         struct btrfs_delayed_ref_root *delayed_refs;
 707         int ret;
 708
 709         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
 710         if (!head_ref)
 711                 return -ENOMEM;
 712
 713         head_ref->extent_op = extent_op;
 714
 715         delayed_refs = &trans->transaction->delayed_refs;
 716         spin_lock(&delayed_refs->lock);
 717
 718         ret = add_delayed_ref_head(trans, &head_ref->node, bytenr,
 719                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
 720                                    extent_op->is_data);
 721         BUG_ON(ret);
 722
 723         spin_unlock(&delayed_refs->lock);
 724         return 0;
 725 }
 726
 727 /*
 728  * this does a simple search for the head node for a given extent.
 729  * It must be called with the delayed ref spinlock held, and it returns
 730  * the head node if any where found, or NULL if not.
 731  */
 732 struct btrfs_delayed_ref_head *
 733 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
 734 {
 735         struct btrfs_delayed_ref_node *ref;
 736         struct btrfs_delayed_ref_root *delayed_refs;
 737
 738         delayed_refs = &trans->transaction->delayed_refs;
 739         ref = find_ref_head(&delayed_refs->root, bytenr, NULL);
 740         if (ref)
 741                 return btrfs_delayed_node_to_head(ref);
 742         return NULL;
 743 }
 744
 745 /*
 746  * add a delayed ref to the tree.  This does all of the accounting required
 747  * to make sure the delayed ref is eventually processed before this
 748  * transaction commits.
 749  *
 750  * The main point of this call is to add and remove a backreference in a single
 751  * shot, taking the lock only once, and only searching for the head node once.
 752  *
 753  * It is the same as doing a ref add and delete in two separate calls.
 754  */
 755 #if 0
 756 int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
 757                           u64 bytenr, u64 num_bytes, u64 orig_parent,
 758                           u64 parent, u64 orig_ref_root, u64 ref_root,
 759                           u64 orig_ref_generation, u64 ref_generation,
 760                           u64 owner_objectid, int pin)
 761 {
 762         struct btrfs_delayed_ref *ref;
 763         struct btrfs_delayed_ref *old_ref;
 764         struct btrfs_delayed_ref_head *head_ref;
 765         struct btrfs_delayed_ref_root *delayed_refs;
 766         int ret;
 767
 768         ref = kmalloc(sizeof(*ref), GFP_NOFS);
 769         if (!ref)
 770                 return -ENOMEM;
 771
 772         old_ref = kmalloc(sizeof(*old_ref), GFP_NOFS);
 773         if (!old_ref) {
 774                 kfree(ref);
 775                 return -ENOMEM;
 776         }
 777
 778         /*
 779          * the parent = 0 case comes from cases where we don't actually
 780          * know the parent yet.  It will get updated later via a add/drop
 781          * pair.
 782          */
 783         if (parent == 0)
 784                 parent = bytenr;
 785         if (orig_parent == 0)
 786                 orig_parent = bytenr;
 787
 788         head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
 789         if (!head_ref) {
 790                 kfree(ref);
 791                 kfree(old_ref);
 792                 return -ENOMEM;
 793         }
 794         delayed_refs = &trans->transaction->delayed_refs;
 795         spin_lock(&delayed_refs->lock);
 796
 797         /*
 798          * insert both the head node and the new ref without dropping
 799          * the spin lock
 800          */
 801         ret = __btrfs_add_delayed_ref(trans, &head_ref->node, bytenr, num_bytes,
 802                                       (u64)-1, 0, 0, 0,
 803                                       BTRFS_UPDATE_DELAYED_HEAD, 0);
 804         BUG_ON(ret);
 805
 806         ret = __btrfs_add_delayed_ref(trans, &ref->node, bytenr, num_bytes,
 807                                       parent, ref_root, ref_generation,
 808                                       owner_objectid, BTRFS_ADD_DELAYED_REF, 0);
 809         BUG_ON(ret);
 810
 811         ret = __btrfs_add_delayed_ref(trans, &old_ref->node, bytenr, num_bytes,
 812                                       orig_parent, orig_ref_root,
 813                                       orig_ref_generation, owner_objectid,
 814                                       BTRFS_DROP_DELAYED_REF, pin);
 815         BUG_ON(ret);
 816         spin_unlock(&delayed_refs->lock);
 817         return 0;
 818 }
 819 #endif