fs/btrfs/delayed-ref.c

   1 /*
   2  * Copyright (C) 2009 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/slab.h>
  21 #include <linux/sort.h>
  22 #include "ctree.h"
  23 #include "delayed-ref.h"
  24 #include "transaction.h"
  25
  26 struct kmem_cache *btrfs_delayed_ref_head_cachep;
  27 struct kmem_cache *btrfs_delayed_tree_ref_cachep;
  28 struct kmem_cache *btrfs_delayed_data_ref_cachep;
  29 struct kmem_cache *btrfs_delayed_extent_op_cachep;
  30 /*
  31  * delayed back reference update tracking.  For subvolume trees
  32  * we queue up extent allocations and backref maintenance for
  33  * delayed processing.   This avoids deep call chains where we
  34  * add extents in the middle of btrfs_search_slot, and it allows
  35  * us to buffer up frequently modified backrefs in an rb tree instead
  36  * of hammering updates on the extent allocation tree.
  37  */
  38
  39 /*
  40  * compare two delayed tree backrefs with same bytenr and type
  41  */
  42 static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref2,
  43                           struct btrfs_delayed_tree_ref *ref1, int type)
  44 {
  45         if (type == BTRFS_TREE_BLOCK_REF_KEY) {
  46                 if (ref1->root < ref2->root)
  47                         return -1;
  48                 if (ref1->root > ref2->root)
  49                         return 1;
  50         } else {
  51                 if (ref1->parent < ref2->parent)
  52                         return -1;
  53                 if (ref1->parent > ref2->parent)
  54                         return 1;
  55         }
  56         return 0;
  57 }
  58
  59 /*
  60  * compare two delayed data backrefs with same bytenr and type
  61  */
  62 static int comp_data_refs(struct btrfs_delayed_data_ref *ref2,
  63                           struct btrfs_delayed_data_ref *ref1)
  64 {
  65         if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
  66                 if (ref1->root < ref2->root)
  67                         return -1;
  68                 if (ref1->root > ref2->root)
  69                         return 1;
  70                 if (ref1->objectid < ref2->objectid)
  71                         return -1;
  72                 if (ref1->objectid > ref2->objectid)
  73                         return 1;
  74                 if (ref1->offset < ref2->offset)
  75                         return -1;
  76                 if (ref1->offset > ref2->offset)
  77                         return 1;
  78         } else {
  79                 if (ref1->parent < ref2->parent)
  80                         return -1;
  81                 if (ref1->parent > ref2->parent)
  82                         return 1;
  83         }
  84         return 0;
  85 }
  86
  87 /*
  88  * entries in the rb tree are ordered by the byte number of the extent,
  89  * type of the delayed backrefs and content of delayed backrefs.
  90  */
  91 static int comp_entry(struct btrfs_delayed_ref_node *ref2,
  92                       struct btrfs_delayed_ref_node *ref1,
  93                       bool compare_seq)
  94 {
  95         if (ref1->bytenr < ref2->bytenr)
  96                 return -1;
  97         if (ref1->bytenr > ref2->bytenr)
  98                 return 1;
  99         if (ref1->is_head && ref2->is_head)
 100                 return 0;
 101         if (ref2->is_head)
 102                 return -1;
 103         if (ref1->is_head)
 104                 return 1;
 105         if (ref1->type < ref2->type)
 106                 return -1;
 107         if (ref1->type > ref2->type)
 108                 return 1;
 109         /* merging of sequenced refs is not allowed */
 110         if (compare_seq) {
 111                 if (ref1->seq < ref2->seq)
 112                         return -1;
 113                 if (ref1->seq > ref2->seq)
 114                         return 1;
 115         }
 116         if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
 117             ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) {
 118                 return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2),
 119                                       btrfs_delayed_node_to_tree_ref(ref1),
 120                                       ref1->type);
 121         } else if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY ||
 122                    ref1->type == BTRFS_SHARED_DATA_REF_KEY) {
 123                 return comp_data_refs(btrfs_delayed_node_to_data_ref(ref2),
 124                                       btrfs_delayed_node_to_data_ref(ref1));
 125         }
 126         BUG();
 127         return 0;
 128 }
 129
 130 /*
 131  * insert a new ref into the rbtree.  This returns any existing refs
 132  * for the same (bytenr,parent) tuple, or NULL if the new node was properly
 133  * inserted.
 134  */
 135 static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root,
 136                                                   struct rb_node *node)
 137 {
 138         struct rb_node **p = &root->rb_node;
 139         struct rb_node *parent_node = NULL;
 140         struct btrfs_delayed_ref_node *entry;
 141         struct btrfs_delayed_ref_node *ins;
 142         int cmp;
 143
 144         ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 145         while (*p) {
 146                 parent_node = *p;
 147                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
 148                                  rb_node);
 149
 150                 cmp = comp_entry(entry, ins, 1);
 151                 if (cmp < 0)
 152                         p = &(*p)->rb_left;
 153                 else if (cmp > 0)
 154                         p = &(*p)->rb_right;
 155                 else
 156                         return entry;
 157         }
 158
 159         rb_link_node(node, parent_node, p);
 160         rb_insert_color(node, root);
 161         return NULL;
 162 }
 163
 164 /* insert a new ref to head ref rbtree */
 165 static struct btrfs_delayed_ref_head *htree_insert(struct rb_root *root,
 166                                                    struct rb_node *node)
 167 {
 168         struct rb_node **p = &root->rb_node;
 169         struct rb_node *parent_node = NULL;
 170         struct btrfs_delayed_ref_head *entry;
 171         struct btrfs_delayed_ref_head *ins;
 172         u64 bytenr;
 173
 174         ins = rb_entry(node, struct btrfs_delayed_ref_head, href_node);
 175         bytenr = ins->node.bytenr;
 176         while (*p) {
 177                 parent_node = *p;
 178                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_head,
 179                                  href_node);
 180
 181                 if (bytenr < entry->node.bytenr)
 182                         p = &(*p)->rb_left;
 183                 else if (bytenr > entry->node.bytenr)
 184                         p = &(*p)->rb_right;
 185                 else
 186                         return entry;
 187         }
 188
 189         rb_link_node(node, parent_node, p);
 190         rb_insert_color(node, root);
 191         return NULL;
 192 }
 193
 194 /*
 195  * find an head entry based on bytenr. This returns the delayed ref
 196  * head if it was able to find one, or NULL if nothing was in that spot.
 197  * If return_bigger is given, the next bigger entry is returned if no exact
 198  * match is found.
 199  */
 200 static struct btrfs_delayed_ref_head *
 201 find_ref_head(struct rb_root *root, u64 bytenr,
 202               struct btrfs_delayed_ref_head **last, int return_bigger)
 203 {
 204         struct rb_node *n;
 205         struct btrfs_delayed_ref_head *entry;
 206         int cmp = 0;
 207
 208 again:
 209         n = root->rb_node;
 210         entry = NULL;
 211         while (n) {
 212                 entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
 213                 if (last)
 214                         *last = entry;
 215
 216                 if (bytenr < entry->node.bytenr)
 217                         cmp = -1;
 218                 else if (bytenr > entry->node.bytenr)
 219                         cmp = 1;
 220                 else
 221                         cmp = 0;
 222
 223                 if (cmp < 0)
 224                         n = n->rb_left;
 225                 else if (cmp > 0)
 226                         n = n->rb_right;
 227                 else
 228                         return entry;
 229         }
 230         if (entry && return_bigger) {
 231                 if (cmp > 0) {
 232                         n = rb_next(&entry->href_node);
 233                         if (!n)
 234                                 n = rb_first(root);
 235                         entry = rb_entry(n, struct btrfs_delayed_ref_head,
 236                                          href_node);
 237                         bytenr = entry->node.bytenr;
 238                         return_bigger = 0;
 239                         goto again;
 240                 }
 241                 return entry;
 242         }
 243         return NULL;
 244 }
 245
 246 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 247                            struct btrfs_delayed_ref_head *head)
 248 {
 249         struct btrfs_delayed_ref_root *delayed_refs;
 250
 251         delayed_refs = &trans->transaction->delayed_refs;
 252         assert_spin_locked(&delayed_refs->lock);
 253         if (mutex_trylock(&head->mutex))
 254                 return 0;
 255
 256         atomic_inc(&head->node.refs);
 257         spin_unlock(&delayed_refs->lock);
 258
 259         mutex_lock(&head->mutex);
 260         spin_lock(&delayed_refs->lock);
 261         if (!head->node.in_tree) {
 262                 mutex_unlock(&head->mutex);
 263                 btrfs_put_delayed_ref(&head->node);
 264                 return -EAGAIN;
 265         }
 266         btrfs_put_delayed_ref(&head->node);
 267         return 0;
 268 }
 269
 270 static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
 271                                     struct btrfs_delayed_ref_root *delayed_refs,
 272                                     struct btrfs_delayed_ref_head *head,
 273                                     struct btrfs_delayed_ref_node *ref)
 274 {
 275         if (btrfs_delayed_ref_is_head(ref)) {
 276                 head = btrfs_delayed_node_to_head(ref);
 277                 rb_erase(&head->href_node, &delayed_refs->href_root);
 278         } else {
 279                 assert_spin_locked(&head->lock);
 280                 rb_erase(&ref->rb_node, &head->ref_root);
 281         }
 282         ref->in_tree = 0;
 283         btrfs_put_delayed_ref(ref);
 284         atomic_dec(&delayed_refs->num_entries);
 285         if (trans->delayed_ref_updates)
 286                 trans->delayed_ref_updates--;
 287 }
 288
 289 static int merge_ref(struct btrfs_trans_handle *trans,
 290                      struct btrfs_delayed_ref_root *delayed_refs,
 291                      struct btrfs_delayed_ref_head *head,
 292                      struct btrfs_delayed_ref_node *ref, u64 seq)
 293 {
 294         struct rb_node *node;
 295         int mod = 0;
 296         int done = 0;
 297
 298         node = rb_next(&ref->rb_node);
 299         while (!done && node) {
 300                 struct btrfs_delayed_ref_node *next;
 301
 302                 next = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 303                 node = rb_next(node);
 304                 if (seq && next->seq >= seq)
 305                         break;
 306                 if (comp_entry(ref, next, 0))
 307                         continue;
 308
 309                 if (ref->action == next->action) {
 310                         mod = next->ref_mod;
 311                 } else {
 312                         if (ref->ref_mod < next->ref_mod) {
 313                                 struct btrfs_delayed_ref_node *tmp;
 314
 315                                 tmp = ref;
 316                                 ref = next;
 317                                 next = tmp;
 318                                 done = 1;
 319                         }
 320                         mod = -next->ref_mod;
 321                 }
 322
 323                 drop_delayed_ref(trans, delayed_refs, head, next);
 324                 ref->ref_mod += mod;
 325                 if (ref->ref_mod == 0) {
 326                         drop_delayed_ref(trans, delayed_refs, head, ref);
 327                         done = 1;
 328                 } else {
 329                         /*
 330                          * You can't have multiples of the same ref on a tree
 331                          * block.
 332                          */
 333                         WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
 334                                 ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
 335                 }
 336         }
 337         return done;
 338 }
 339
 340 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 341                               struct btrfs_fs_info *fs_info,
 342                               struct btrfs_delayed_ref_root *delayed_refs,
 343                               struct btrfs_delayed_ref_head *head)
 344 {
 345         struct rb_node *node;
 346         u64 seq = 0;
 347
 348         assert_spin_locked(&head->lock);
 349         /*
 350          * We don't have too much refs to merge in the case of delayed data
 351          * refs.
 352          */
 353         if (head->is_data)
 354                 return;
 355
 356         spin_lock(&fs_info->tree_mod_seq_lock);
 357         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 358                 struct seq_list *elem;
 359
 360                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 361                                         struct seq_list, list);
 362                 seq = elem->seq;
 363         }
 364         spin_unlock(&fs_info->tree_mod_seq_lock);
 365
 366         node = rb_first(&head->ref_root);
 367         while (node) {
 368                 struct btrfs_delayed_ref_node *ref;
 369
 370                 ref = rb_entry(node, struct btrfs_delayed_ref_node,
 371                                rb_node);
 372                 /* We can't merge refs that are outside of our seq count */
 373                 if (seq && ref->seq >= seq)
 374                         break;
 375                 if (merge_ref(trans, delayed_refs, head, ref, seq))
 376                         node = rb_first(&head->ref_root);
 377                 else
 378                         node = rb_next(&ref->rb_node);
 379         }
 380 }
 381
 382 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 383                             struct btrfs_delayed_ref_root *delayed_refs,
 384                             u64 seq)
 385 {
 386         struct seq_list *elem;
 387         int ret = 0;
 388
 389         spin_lock(&fs_info->tree_mod_seq_lock);
 390         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 391                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 392                                         struct seq_list, list);
 393                 if (seq >= elem->seq) {
 394                         pr_debug("holding back delayed_ref %#x.%x, lowest is %#x.%x (%p)\n",
 395                                  (u32)(seq >> 32), (u32)seq,
 396                                  (u32)(elem->seq >> 32), (u32)elem->seq,
 397                                  delayed_refs);
 398                         ret = 1;
 399                 }
 400         }
 401
 402         spin_unlock(&fs_info->tree_mod_seq_lock);
 403         return ret;
 404 }
 405
 406 struct btrfs_delayed_ref_head *
 407 btrfs_select_ref_head(struct btrfs_trans_handle *trans)
 408 {
 409         struct btrfs_delayed_ref_root *delayed_refs;
 410         struct btrfs_delayed_ref_head *head;
 411         u64 start;
 412         bool loop = false;
 413
 414         delayed_refs = &trans->transaction->delayed_refs;
 415
 416 again:
 417         start = delayed_refs->run_delayed_start;
 418         head = find_ref_head(&delayed_refs->href_root, start, NULL, 1);
 419         if (!head && !loop) {
 420                 delayed_refs->run_delayed_start = 0;
 421                 start = 0;
 422                 loop = true;
 423                 head = find_ref_head(&delayed_refs->href_root, start, NULL, 1);
 424                 if (!head)
 425                         return NULL;
 426         } else if (!head && loop) {
 427                 return NULL;
 428         }
 429
 430         while (head->processing) {
 431                 struct rb_node *node;
 432
 433                 node = rb_next(&head->href_node);
 434                 if (!node) {
 435                         if (loop)
 436                                 return NULL;
 437                         delayed_refs->run_delayed_start = 0;
 438                         start = 0;
 439                         loop = true;
 440                         goto again;
 441                 }
 442                 head = rb_entry(node, struct btrfs_delayed_ref_head,
 443                                 href_node);
 444         }
 445
 446         head->processing = 1;
 447         WARN_ON(delayed_refs->num_heads_ready == 0);
 448         delayed_refs->num_heads_ready--;
 449         delayed_refs->run_delayed_start = head->node.bytenr +
 450                 head->node.num_bytes;
 451         return head;
 452 }
 453
 454 /*
 455  * helper function to update an extent delayed ref in the
 456  * rbtree.  existing and update must both have the same
 457  * bytenr and parent
 458  *
 459  * This may free existing if the update cancels out whatever
 460  * operation it was doing.
 461  */
 462 static noinline void
 463 update_existing_ref(struct btrfs_trans_handle *trans,
 464                     struct btrfs_delayed_ref_root *delayed_refs,
 465                     struct btrfs_delayed_ref_head *head,
 466                     struct btrfs_delayed_ref_node *existing,
 467                     struct btrfs_delayed_ref_node *update)
 468 {
 469         if (update->action != existing->action) {
 470                 /*
 471                  * this is effectively undoing either an add or a
 472                  * drop.  We decrement the ref_mod, and if it goes
 473                  * down to zero we just delete the entry without
 474                  * every changing the extent allocation tree.
 475                  */
 476                 existing->ref_mod--;
 477                 if (existing->ref_mod == 0)
 478                         drop_delayed_ref(trans, delayed_refs, head, existing);
 479                 else
 480                         WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 481                                 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 482         } else {
 483                 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 484                         existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 485                 /*
 486                  * the action on the existing ref matches
 487                  * the action on the ref we're trying to add.
 488                  * Bump the ref_mod by one so the backref that
 489                  * is eventually added/removed has the correct
 490                  * reference count
 491                  */
 492                 existing->ref_mod += update->ref_mod;
 493         }
 494 }
 495
 496 /*
 497  * helper function to update the accounting in the head ref
 498  * existing and update must have the same bytenr
 499  */
 500 static noinline void
 501 update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
 502                          struct btrfs_delayed_ref_node *update)
 503 {
 504         struct btrfs_delayed_ref_head *existing_ref;
 505         struct btrfs_delayed_ref_head *ref;
 506
 507         existing_ref = btrfs_delayed_node_to_head(existing);
 508         ref = btrfs_delayed_node_to_head(update);
 509         BUG_ON(existing_ref->is_data != ref->is_data);
 510
 511         if (ref->must_insert_reserved) {
 512                 /* if the extent was freed and then
 513                  * reallocated before the delayed ref
 514                  * entries were processed, we can end up
 515                  * with an existing head ref without
 516                  * the must_insert_reserved flag set.
 517                  * Set it again here
 518                  */
 519                 existing_ref->must_insert_reserved = ref->must_insert_reserved;
 520
 521                 /*
 522                  * update the num_bytes so we make sure the accounting
 523                  * is done correctly
 524                  */
 525                 existing->num_bytes = update->num_bytes;
 526
 527         }
 528
 529         if (ref->extent_op) {
 530                 if (!existing_ref->extent_op) {
 531                         existing_ref->extent_op = ref->extent_op;
 532                 } else {
 533                         if (ref->extent_op->update_key) {
 534                                 memcpy(&existing_ref->extent_op->key,
 535                                        &ref->extent_op->key,
 536                                        sizeof(ref->extent_op->key));
 537                                 existing_ref->extent_op->update_key = 1;
 538                         }
 539                         if (ref->extent_op->update_flags) {
 540                                 existing_ref->extent_op->flags_to_set |=
 541                                         ref->extent_op->flags_to_set;
 542                                 existing_ref->extent_op->update_flags = 1;
 543                         }
 544                         btrfs_free_delayed_extent_op(ref->extent_op);
 545                 }
 546         }
 547         /*
 548          * update the reference mod on the head to reflect this new operation,
 549          * only need the lock for this case cause we could be processing it
 550          * currently, for refs we just added we know we're a-ok.
 551          */
 552         spin_lock(&existing_ref->lock);
 553         existing->ref_mod += update->ref_mod;
 554         spin_unlock(&existing_ref->lock);
 555 }
 556
 557 /*
 558  * helper function to actually insert a head node into the rbtree.
 559  * this does all the dirty work in terms of maintaining the correct
 560  * overall modification count.
 561  */
 562 static noinline struct btrfs_delayed_ref_head *
 563 add_delayed_ref_head(struct btrfs_fs_info *fs_info,
 564                      struct btrfs_trans_handle *trans,
 565                      struct btrfs_delayed_ref_node *ref, u64 bytenr,
 566                      u64 num_bytes, int action, int is_data)
 567 {
 568         struct btrfs_delayed_ref_head *existing;
 569         struct btrfs_delayed_ref_head *head_ref = NULL;
 570         struct btrfs_delayed_ref_root *delayed_refs;
 571         int count_mod = 1;
 572         int must_insert_reserved = 0;
 573
 574         /*
 575          * the head node stores the sum of all the mods, so dropping a ref
 576          * should drop the sum in the head node by one.
 577          */
 578         if (action == BTRFS_UPDATE_DELAYED_HEAD)
 579                 count_mod = 0;
 580         else if (action == BTRFS_DROP_DELAYED_REF)
 581                 count_mod = -1;
 582
 583         /*
 584          * BTRFS_ADD_DELAYED_EXTENT means that we need to update
 585          * the reserved accounting when the extent is finally added, or
 586          * if a later modification deletes the delayed ref without ever
 587          * inserting the extent into the extent allocation tree.
 588          * ref->must_insert_reserved is the flag used to record
 589          * that accounting mods are required.
 590          *
 591          * Once we record must_insert_reserved, switch the action to
 592          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
 593          */
 594         if (action == BTRFS_ADD_DELAYED_EXTENT)
 595                 must_insert_reserved = 1;
 596         else
 597                 must_insert_reserved = 0;
 598
 599         delayed_refs = &trans->transaction->delayed_refs;
 600
 601         /* first set the basic ref node struct up */
 602         atomic_set(&ref->refs, 1);
 603         ref->bytenr = bytenr;
 604         ref->num_bytes = num_bytes;
 605         ref->ref_mod = count_mod;
 606         ref->type  = 0;
 607         ref->action  = 0;
 608         ref->is_head = 1;
 609         ref->in_tree = 1;
 610         ref->seq = 0;
 611
 612         head_ref = btrfs_delayed_node_to_head(ref);
 613         head_ref->must_insert_reserved = must_insert_reserved;
 614         head_ref->is_data = is_data;
 615         head_ref->ref_root = RB_ROOT;
 616         head_ref->processing = 0;
 617
 618         spin_lock_init(&head_ref->lock);
 619         mutex_init(&head_ref->mutex);
 620
 621         trace_add_delayed_ref_head(ref, head_ref, action);
 622
 623         existing = htree_insert(&delayed_refs->href_root,
 624                                 &head_ref->href_node);
 625         if (existing) {
 626                 update_existing_head_ref(&existing->node, ref);
 627                 /*
 628                  * we've updated the existing ref, free the newly
 629                  * allocated ref
 630                  */
 631                 kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 632                 head_ref = existing;
 633         } else {
 634                 delayed_refs->num_heads++;
 635                 delayed_refs->num_heads_ready++;
 636                 atomic_inc(&delayed_refs->num_entries);
 637                 trans->delayed_ref_updates++;
 638         }
 639         return head_ref;
 640 }
 641
 642 /*
 643  * helper to insert a delayed tree ref into the rbtree.
 644  */
 645 static noinline void
 646 add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 647                      struct btrfs_trans_handle *trans,
 648                      struct btrfs_delayed_ref_head *head_ref,
 649                      struct btrfs_delayed_ref_node *ref, u64 bytenr,
 650                      u64 num_bytes, u64 parent, u64 ref_root, int level,
 651                      int action, int for_cow)
 652 {
 653         struct btrfs_delayed_ref_node *existing;
 654         struct btrfs_delayed_tree_ref *full_ref;
 655         struct btrfs_delayed_ref_root *delayed_refs;
 656         u64 seq = 0;
 657
 658         if (action == BTRFS_ADD_DELAYED_EXTENT)
 659                 action = BTRFS_ADD_DELAYED_REF;
 660
 661         delayed_refs = &trans->transaction->delayed_refs;
 662
 663         /* first set the basic ref node struct up */
 664         atomic_set(&ref->refs, 1);
 665         ref->bytenr = bytenr;
 666         ref->num_bytes = num_bytes;
 667         ref->ref_mod = 1;
 668         ref->action = action;
 669         ref->is_head = 0;
 670         ref->in_tree = 1;
 671
 672         if (need_ref_seq(for_cow, ref_root))
 673                 seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 674         ref->seq = seq;
 675
 676         full_ref = btrfs_delayed_node_to_tree_ref(ref);
 677         full_ref->parent = parent;
 678         full_ref->root = ref_root;
 679         if (parent)
 680                 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
 681         else
 682                 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
 683         full_ref->level = level;
 684
 685         trace_add_delayed_tree_ref(ref, full_ref, action);
 686
 687         spin_lock(&head_ref->lock);
 688         existing = tree_insert(&head_ref->ref_root, &ref->rb_node);
 689         if (existing) {
 690                 update_existing_ref(trans, delayed_refs, head_ref, existing,
 691                                     ref);
 692                 /*
 693                  * we've updated the existing ref, free the newly
 694                  * allocated ref
 695                  */
 696                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, full_ref);
 697         } else {
 698                 atomic_inc(&delayed_refs->num_entries);
 699                 trans->delayed_ref_updates++;
 700         }
 701         spin_unlock(&head_ref->lock);
 702 }
 703
 704 /*
 705  * helper to insert a delayed data ref into the rbtree.
 706  */
 707 static noinline void
 708 add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 709                      struct btrfs_trans_handle *trans,
 710                      struct btrfs_delayed_ref_head *head_ref,
 711                      struct btrfs_delayed_ref_node *ref, u64 bytenr,
 712                      u64 num_bytes, u64 parent, u64 ref_root, u64 owner,
 713                      u64 offset, int action, int for_cow)
 714 {
 715         struct btrfs_delayed_ref_node *existing;
 716         struct btrfs_delayed_data_ref *full_ref;
 717         struct btrfs_delayed_ref_root *delayed_refs;
 718         u64 seq = 0;
 719
 720         if (action == BTRFS_ADD_DELAYED_EXTENT)
 721                 action = BTRFS_ADD_DELAYED_REF;
 722
 723         delayed_refs = &trans->transaction->delayed_refs;
 724
 725         /* first set the basic ref node struct up */
 726         atomic_set(&ref->refs, 1);
 727         ref->bytenr = bytenr;
 728         ref->num_bytes = num_bytes;
 729         ref->ref_mod = 1;
 730         ref->action = action;
 731         ref->is_head = 0;
 732         ref->in_tree = 1;
 733
 734         if (need_ref_seq(for_cow, ref_root))
 735                 seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 736         ref->seq = seq;
 737
 738         full_ref = btrfs_delayed_node_to_data_ref(ref);
 739         full_ref->parent = parent;
 740         full_ref->root = ref_root;
 741         if (parent)
 742                 ref->type = BTRFS_SHARED_DATA_REF_KEY;
 743         else
 744                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
 745
 746         full_ref->objectid = owner;
 747         full_ref->offset = offset;
 748
 749         trace_add_delayed_data_ref(ref, full_ref, action);
 750
 751         spin_lock(&head_ref->lock);
 752         existing = tree_insert(&head_ref->ref_root, &ref->rb_node);
 753         if (existing) {
 754                 update_existing_ref(trans, delayed_refs, head_ref, existing,
 755                                     ref);
 756                 /*
 757                  * we've updated the existing ref, free the newly
 758                  * allocated ref
 759                  */
 760                 kmem_cache_free(btrfs_delayed_data_ref_cachep, full_ref);
 761         } else {
 762                 atomic_inc(&delayed_refs->num_entries);
 763                 trans->delayed_ref_updates++;
 764         }
 765         spin_unlock(&head_ref->lock);
 766 }
 767
 768 /*
 769  * add a delayed tree ref.  This does all of the accounting required
 770  * to make sure the delayed ref is eventually processed before this
 771  * transaction commits.
 772  */
 773 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 774                                struct btrfs_trans_handle *trans,
 775                                u64 bytenr, u64 num_bytes, u64 parent,
 776                                u64 ref_root,  int level, int action,
 777                                struct btrfs_delayed_extent_op *extent_op,
 778                                int for_cow)
 779 {
 780         struct btrfs_delayed_tree_ref *ref;
 781         struct btrfs_delayed_ref_head *head_ref;
 782         struct btrfs_delayed_ref_root *delayed_refs;
 783
 784         BUG_ON(extent_op && extent_op->is_data);
 785         ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
 786         if (!ref)
 787                 return -ENOMEM;
 788
 789         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 790         if (!head_ref) {
 791                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 792                 return -ENOMEM;
 793         }
 794
 795         head_ref->extent_op = extent_op;
 796
 797         delayed_refs = &trans->transaction->delayed_refs;
 798         spin_lock(&delayed_refs->lock);
 799
 800         /*
 801          * insert both the head node and the new ref without dropping
 802          * the spin lock
 803          */
 804         head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node,
 805                                         bytenr, num_bytes, action, 0);
 806
 807         add_delayed_tree_ref(fs_info, trans, head_ref, &ref->node, bytenr,
 808                                    num_bytes, parent, ref_root, level, action,
 809                                    for_cow);
 810         spin_unlock(&delayed_refs->lock);
 811         if (need_ref_seq(for_cow, ref_root))
 812                 btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 813
 814         return 0;
 815 }
 816
 817 /*
 818  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 819  */
 820 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 821                                struct btrfs_trans_handle *trans,
 822                                u64 bytenr, u64 num_bytes,
 823                                u64 parent, u64 ref_root,
 824                                u64 owner, u64 offset, int action,
 825                                struct btrfs_delayed_extent_op *extent_op,
 826                                int for_cow)
 827 {
 828         struct btrfs_delayed_data_ref *ref;
 829         struct btrfs_delayed_ref_head *head_ref;
 830         struct btrfs_delayed_ref_root *delayed_refs;
 831
 832         BUG_ON(extent_op && !extent_op->is_data);
 833         ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
 834         if (!ref)
 835                 return -ENOMEM;
 836
 837         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 838         if (!head_ref) {
 839                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 840                 return -ENOMEM;
 841         }
 842
 843         head_ref->extent_op = extent_op;
 844
 845         delayed_refs = &trans->transaction->delayed_refs;
 846         spin_lock(&delayed_refs->lock);
 847
 848         /*
 849          * insert both the head node and the new ref without dropping
 850          * the spin lock
 851          */
 852         head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node,
 853                                         bytenr, num_bytes, action, 1);
 854
 855         add_delayed_data_ref(fs_info, trans, head_ref, &ref->node, bytenr,
 856                                    num_bytes, parent, ref_root, owner, offset,
 857                                    action, for_cow);
 858         spin_unlock(&delayed_refs->lock);
 859         if (need_ref_seq(for_cow, ref_root))
 860                 btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 861
 862         return 0;
 863 }
 864
 865 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 866                                 struct btrfs_trans_handle *trans,
 867                                 u64 bytenr, u64 num_bytes,
 868                                 struct btrfs_delayed_extent_op *extent_op)
 869 {
 870         struct btrfs_delayed_ref_head *head_ref;
 871         struct btrfs_delayed_ref_root *delayed_refs;
 872
 873         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 874         if (!head_ref)
 875                 return -ENOMEM;
 876
 877         head_ref->extent_op = extent_op;
 878
 879         delayed_refs = &trans->transaction->delayed_refs;
 880         spin_lock(&delayed_refs->lock);
 881
 882         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 883                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
 884                                    extent_op->is_data);
 885
 886         spin_unlock(&delayed_refs->lock);
 887         return 0;
 888 }
 889
 890 /*
 891  * this does a simple search for the head node for a given extent.
 892  * It must be called with the delayed ref spinlock held, and it returns
 893  * the head node if any where found, or NULL if not.
 894  */
 895 struct btrfs_delayed_ref_head *
 896 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
 897 {
 898         struct btrfs_delayed_ref_root *delayed_refs;
 899
 900         delayed_refs = &trans->transaction->delayed_refs;
 901         return find_ref_head(&delayed_refs->href_root, bytenr, NULL, 0);
 902 }
 903
 904 void btrfs_delayed_ref_exit(void)
 905 {
 906         if (btrfs_delayed_ref_head_cachep)
 907                 kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
 908         if (btrfs_delayed_tree_ref_cachep)
 909                 kmem_cache_destroy(btrfs_delayed_tree_ref_cachep);
 910         if (btrfs_delayed_data_ref_cachep)
 911                 kmem_cache_destroy(btrfs_delayed_data_ref_cachep);
 912         if (btrfs_delayed_extent_op_cachep)
 913                 kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
 914 }
 915
 916 int btrfs_delayed_ref_init(void)
 917 {
 918         btrfs_delayed_ref_head_cachep = kmem_cache_create(
 919                                 "btrfs_delayed_ref_head",
 920                                 sizeof(struct btrfs_delayed_ref_head), 0,
 921                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 922         if (!btrfs_delayed_ref_head_cachep)
 923                 goto fail;
 924
 925         btrfs_delayed_tree_ref_cachep = kmem_cache_create(
 926                                 "btrfs_delayed_tree_ref",
 927                                 sizeof(struct btrfs_delayed_tree_ref), 0,
 928                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 929         if (!btrfs_delayed_tree_ref_cachep)
 930                 goto fail;
 931
 932         btrfs_delayed_data_ref_cachep = kmem_cache_create(
 933                                 "btrfs_delayed_data_ref",
 934                                 sizeof(struct btrfs_delayed_data_ref), 0,
 935                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 936         if (!btrfs_delayed_data_ref_cachep)
 937                 goto fail;
 938
 939         btrfs_delayed_extent_op_cachep = kmem_cache_create(
 940                                 "btrfs_delayed_extent_op",
 941                                 sizeof(struct btrfs_delayed_extent_op), 0,
 942                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 943         if (!btrfs_delayed_extent_op_cachep)
 944                 goto fail;
 945
 946         return 0;
 947 fail:
 948         btrfs_delayed_ref_exit();
 949         return -ENOMEM;
 950 }