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