kernel/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         if (ref1->no_quota > ref2->no_quota)
 110                 return 1;
 111         if (ref1->no_quota < ref2->no_quota)
 112                 return -1;
 113         /* merging of sequenced refs is not allowed */
 114         if (compare_seq) {
 115                 if (ref1->seq < ref2->seq)
 116                         return -1;
 117                 if (ref1->seq > ref2->seq)
 118                         return 1;
 119         }
 120         if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
 121             ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) {
 122                 return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2),
 123                                       btrfs_delayed_node_to_tree_ref(ref1),
 124                                       ref1->type);
 125         } else if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY ||
 126                    ref1->type == BTRFS_SHARED_DATA_REF_KEY) {
 127                 return comp_data_refs(btrfs_delayed_node_to_data_ref(ref2),
 128                                       btrfs_delayed_node_to_data_ref(ref1));
 129         }
 130         BUG();
 131         return 0;
 132 }
 133
 134 /*
 135  * insert a new ref into the rbtree.  This returns any existing refs
 136  * for the same (bytenr,parent) tuple, or NULL if the new node was properly
 137  * inserted.
 138  */
 139 static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root,
 140                                                   struct rb_node *node)
 141 {
 142         struct rb_node **p = &root->rb_node;
 143         struct rb_node *parent_node = NULL;
 144         struct btrfs_delayed_ref_node *entry;
 145         struct btrfs_delayed_ref_node *ins;
 146         int cmp;
 147
 148         ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 149         while (*p) {
 150                 parent_node = *p;
 151                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
 152                                  rb_node);
 153
 154                 cmp = comp_entry(entry, ins, 1);
 155                 if (cmp < 0)
 156                         p = &(*p)->rb_left;
 157                 else if (cmp > 0)
 158                         p = &(*p)->rb_right;
 159                 else
 160                         return entry;
 161         }
 162
 163         rb_link_node(node, parent_node, p);
 164         rb_insert_color(node, root);
 165         return NULL;
 166 }
 167
 168 /* insert a new ref to head ref rbtree */
 169 static struct btrfs_delayed_ref_head *htree_insert(struct rb_root *root,
 170                                                    struct rb_node *node)
 171 {
 172         struct rb_node **p = &root->rb_node;
 173         struct rb_node *parent_node = NULL;
 174         struct btrfs_delayed_ref_head *entry;
 175         struct btrfs_delayed_ref_head *ins;
 176         u64 bytenr;
 177
 178         ins = rb_entry(node, struct btrfs_delayed_ref_head, href_node);
 179         bytenr = ins->node.bytenr;
 180         while (*p) {
 181                 parent_node = *p;
 182                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_head,
 183                                  href_node);
 184
 185                 if (bytenr < entry->node.bytenr)
 186                         p = &(*p)->rb_left;
 187                 else if (bytenr > entry->node.bytenr)
 188                         p = &(*p)->rb_right;
 189                 else
 190                         return entry;
 191         }
 192
 193         rb_link_node(node, parent_node, p);
 194         rb_insert_color(node, root);
 195         return NULL;
 196 }
 197
 198 /*
 199  * find an head entry based on bytenr. This returns the delayed ref
 200  * head if it was able to find one, or NULL if nothing was in that spot.
 201  * If return_bigger is given, the next bigger entry is returned if no exact
 202  * match is found.
 203  */
 204 static struct btrfs_delayed_ref_head *
 205 find_ref_head(struct rb_root *root, u64 bytenr,
 206               int return_bigger)
 207 {
 208         struct rb_node *n;
 209         struct btrfs_delayed_ref_head *entry;
 210
 211         n = root->rb_node;
 212         entry = NULL;
 213         while (n) {
 214                 entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
 215
 216                 if (bytenr < entry->node.bytenr)
 217                         n = n->rb_left;
 218                 else if (bytenr > entry->node.bytenr)
 219                         n = n->rb_right;
 220                 else
 221                         return entry;
 222         }
 223         if (entry && return_bigger) {
 224                 if (bytenr > entry->node.bytenr) {
 225                         n = rb_next(&entry->href_node);
 226                         if (!n)
 227                                 n = rb_first(root);
 228                         entry = rb_entry(n, struct btrfs_delayed_ref_head,
 229                                          href_node);
 230                         return entry;
 231                 }
 232                 return entry;
 233         }
 234         return NULL;
 235 }
 236
 237 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 238                            struct btrfs_delayed_ref_head *head)
 239 {
 240         struct btrfs_delayed_ref_root *delayed_refs;
 241
 242         delayed_refs = &trans->transaction->delayed_refs;
 243         assert_spin_locked(&delayed_refs->lock);
 244         if (mutex_trylock(&head->mutex))
 245                 return 0;
 246
 247         atomic_inc(&head->node.refs);
 248         spin_unlock(&delayed_refs->lock);
 249
 250         mutex_lock(&head->mutex);
 251         spin_lock(&delayed_refs->lock);
 252         if (!head->node.in_tree) {
 253                 mutex_unlock(&head->mutex);
 254                 btrfs_put_delayed_ref(&head->node);
 255                 return -EAGAIN;
 256         }
 257         btrfs_put_delayed_ref(&head->node);
 258         return 0;
 259 }
 260
 261 static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
 262                                     struct btrfs_delayed_ref_root *delayed_refs,
 263                                     struct btrfs_delayed_ref_head *head,
 264                                     struct btrfs_delayed_ref_node *ref)
 265 {
 266         if (btrfs_delayed_ref_is_head(ref)) {
 267                 head = btrfs_delayed_node_to_head(ref);
 268                 rb_erase(&head->href_node, &delayed_refs->href_root);
 269         } else {
 270                 assert_spin_locked(&head->lock);
 271                 rb_erase(&ref->rb_node, &head->ref_root);
 272         }
 273         ref->in_tree = 0;
 274         btrfs_put_delayed_ref(ref);
 275         atomic_dec(&delayed_refs->num_entries);
 276         if (trans->delayed_ref_updates)
 277                 trans->delayed_ref_updates--;
 278 }
 279
 280 static int merge_ref(struct btrfs_trans_handle *trans,
 281                      struct btrfs_delayed_ref_root *delayed_refs,
 282                      struct btrfs_delayed_ref_head *head,
 283                      struct btrfs_delayed_ref_node *ref, u64 seq)
 284 {
 285         struct rb_node *node;
 286         int mod = 0;
 287         int done = 0;
 288
 289         node = rb_next(&ref->rb_node);
 290         while (!done && node) {
 291                 struct btrfs_delayed_ref_node *next;
 292
 293                 next = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
 294                 node = rb_next(node);
 295                 if (seq && next->seq >= seq)
 296                         break;
 297                 if (comp_entry(ref, next, 0))
 298                         continue;
 299
 300                 if (ref->action == next->action) {
 301                         mod = next->ref_mod;
 302                 } else {
 303                         if (ref->ref_mod < next->ref_mod) {
 304                                 struct btrfs_delayed_ref_node *tmp;
 305
 306                                 tmp = ref;
 307                                 ref = next;
 308                                 next = tmp;
 309                                 done = 1;
 310                         }
 311                         mod = -next->ref_mod;
 312                 }
 313
 314                 drop_delayed_ref(trans, delayed_refs, head, next);
 315                 ref->ref_mod += mod;
 316                 if (ref->ref_mod == 0) {
 317                         drop_delayed_ref(trans, delayed_refs, head, ref);
 318                         done = 1;
 319                 } else {
 320                         /*
 321                          * You can't have multiples of the same ref on a tree
 322                          * block.
 323                          */
 324                         WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
 325                                 ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
 326                 }
 327         }
 328         return done;
 329 }
 330
 331 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 332                               struct btrfs_fs_info *fs_info,
 333                               struct btrfs_delayed_ref_root *delayed_refs,
 334                               struct btrfs_delayed_ref_head *head)
 335 {
 336         struct rb_node *node;
 337         u64 seq = 0;
 338
 339         assert_spin_locked(&head->lock);
 340         /*
 341          * We don't have too much refs to merge in the case of delayed data
 342          * refs.
 343          */
 344         if (head->is_data)
 345                 return;
 346
 347         spin_lock(&fs_info->tree_mod_seq_lock);
 348         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 349                 struct seq_list *elem;
 350
 351                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 352                                         struct seq_list, list);
 353                 seq = elem->seq;
 354         }
 355         spin_unlock(&fs_info->tree_mod_seq_lock);
 356
 357         node = rb_first(&head->ref_root);
 358         while (node) {
 359                 struct btrfs_delayed_ref_node *ref;
 360
 361                 ref = rb_entry(node, struct btrfs_delayed_ref_node,
 362                                rb_node);
 363                 /* We can't merge refs that are outside of our seq count */
 364                 if (seq && ref->seq >= seq)
 365                         break;
 366                 if (merge_ref(trans, delayed_refs, head, ref, seq))
 367                         node = rb_first(&head->ref_root);
 368                 else
 369                         node = rb_next(&ref->rb_node);
 370         }
 371 }
 372
 373 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 374                             struct btrfs_delayed_ref_root *delayed_refs,
 375                             u64 seq)
 376 {
 377         struct seq_list *elem;
 378         int ret = 0;
 379
 380         spin_lock(&fs_info->tree_mod_seq_lock);
 381         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 382                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 383                                         struct seq_list, list);
 384                 if (seq >= elem->seq) {
 385                         pr_debug("holding back delayed_ref %#x.%x, lowest is %#x.%x (%p)\n",
 386                                  (u32)(seq >> 32), (u32)seq,
 387                                  (u32)(elem->seq >> 32), (u32)elem->seq,
 388                                  delayed_refs);
 389                         ret = 1;
 390                 }
 391         }
 392
 393         spin_unlock(&fs_info->tree_mod_seq_lock);
 394         return ret;
 395 }
 396
 397 struct btrfs_delayed_ref_head *
 398 btrfs_select_ref_head(struct btrfs_trans_handle *trans)
 399 {
 400         struct btrfs_delayed_ref_root *delayed_refs;
 401         struct btrfs_delayed_ref_head *head;
 402         u64 start;
 403         bool loop = false;
 404
 405         delayed_refs = &trans->transaction->delayed_refs;
 406
 407 again:
 408         start = delayed_refs->run_delayed_start;
 409         head = find_ref_head(&delayed_refs->href_root, start, 1);
 410         if (!head && !loop) {
 411                 delayed_refs->run_delayed_start = 0;
 412                 start = 0;
 413                 loop = true;
 414                 head = find_ref_head(&delayed_refs->href_root, start, 1);
 415                 if (!head)
 416                         return NULL;
 417         } else if (!head && loop) {
 418                 return NULL;
 419         }
 420
 421         while (head->processing) {
 422                 struct rb_node *node;
 423
 424                 node = rb_next(&head->href_node);
 425                 if (!node) {
 426                         if (loop)
 427                                 return NULL;
 428                         delayed_refs->run_delayed_start = 0;
 429                         start = 0;
 430                         loop = true;
 431                         goto again;
 432                 }
 433                 head = rb_entry(node, struct btrfs_delayed_ref_head,
 434                                 href_node);
 435         }
 436
 437         head->processing = 1;
 438         WARN_ON(delayed_refs->num_heads_ready == 0);
 439         delayed_refs->num_heads_ready--;
 440         delayed_refs->run_delayed_start = head->node.bytenr +
 441                 head->node.num_bytes;
 442         return head;
 443 }
 444
 445 /*
 446  * helper function to update an extent delayed ref in the
 447  * rbtree.  existing and update must both have the same
 448  * bytenr and parent
 449  *
 450  * This may free existing if the update cancels out whatever
 451  * operation it was doing.
 452  */
 453 static noinline void
 454 update_existing_ref(struct btrfs_trans_handle *trans,
 455                     struct btrfs_delayed_ref_root *delayed_refs,
 456                     struct btrfs_delayed_ref_head *head,
 457                     struct btrfs_delayed_ref_node *existing,
 458                     struct btrfs_delayed_ref_node *update)
 459 {
 460         if (update->action != existing->action) {
 461                 /*
 462                  * this is effectively undoing either an add or a
 463                  * drop.  We decrement the ref_mod, and if it goes
 464                  * down to zero we just delete the entry without
 465                  * every changing the extent allocation tree.
 466                  */
 467                 existing->ref_mod--;
 468                 if (existing->ref_mod == 0)
 469                         drop_delayed_ref(trans, delayed_refs, head, existing);
 470                 else
 471                         WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 472                                 existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 473         } else {
 474                 WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
 475                         existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
 476                 /*
 477                  * the action on the existing ref matches
 478                  * the action on the ref we're trying to add.
 479                  * Bump the ref_mod by one so the backref that
 480                  * is eventually added/removed has the correct
 481                  * reference count
 482                  */
 483                 existing->ref_mod += update->ref_mod;
 484         }
 485 }
 486
 487 /*
 488  * helper function to update the accounting in the head ref
 489  * existing and update must have the same bytenr
 490  */
 491 static noinline void
 492 update_existing_head_ref(struct btrfs_delayed_ref_root *delayed_refs,
 493                          struct btrfs_delayed_ref_node *existing,
 494                          struct btrfs_delayed_ref_node *update)
 495 {
 496         struct btrfs_delayed_ref_head *existing_ref;
 497         struct btrfs_delayed_ref_head *ref;
 498         int old_ref_mod;
 499
 500         existing_ref = btrfs_delayed_node_to_head(existing);
 501         ref = btrfs_delayed_node_to_head(update);
 502         BUG_ON(existing_ref->is_data != ref->is_data);
 503
 504         spin_lock(&existing_ref->lock);
 505         if (ref->must_insert_reserved) {
 506                 /* if the extent was freed and then
 507                  * reallocated before the delayed ref
 508                  * entries were processed, we can end up
 509                  * with an existing head ref without
 510                  * the must_insert_reserved flag set.
 511                  * Set it again here
 512                  */
 513                 existing_ref->must_insert_reserved = ref->must_insert_reserved;
 514
 515                 /*
 516                  * update the num_bytes so we make sure the accounting
 517                  * is done correctly
 518                  */
 519                 existing->num_bytes = update->num_bytes;
 520
 521         }
 522
 523         if (ref->extent_op) {
 524                 if (!existing_ref->extent_op) {
 525                         existing_ref->extent_op = ref->extent_op;
 526                 } else {
 527                         if (ref->extent_op->update_key) {
 528                                 memcpy(&existing_ref->extent_op->key,
 529                                        &ref->extent_op->key,
 530                                        sizeof(ref->extent_op->key));
 531                                 existing_ref->extent_op->update_key = 1;
 532                         }
 533                         if (ref->extent_op->update_flags) {
 534                                 existing_ref->extent_op->flags_to_set |=
 535                                         ref->extent_op->flags_to_set;
 536                                 existing_ref->extent_op->update_flags = 1;
 537                         }
 538                         btrfs_free_delayed_extent_op(ref->extent_op);
 539                 }
 540         }
 541         /*
 542          * update the reference mod on the head to reflect this new operation,
 543          * only need the lock for this case cause we could be processing it
 544          * currently, for refs we just added we know we're a-ok.
 545          */
 546         old_ref_mod = existing_ref->total_ref_mod;
 547         existing->ref_mod += update->ref_mod;
 548         existing_ref->total_ref_mod += update->ref_mod;
 549
 550         /*
 551          * If we are going to from a positive ref mod to a negative or vice
 552          * versa we need to make sure to adjust pending_csums accordingly.
 553          */
 554         if (existing_ref->is_data) {
 555                 if (existing_ref->total_ref_mod >= 0 && old_ref_mod < 0)
 556                         delayed_refs->pending_csums -= existing->num_bytes;
 557                 if (existing_ref->total_ref_mod < 0 && old_ref_mod >= 0)
 558                         delayed_refs->pending_csums += existing->num_bytes;
 559         }
 560         spin_unlock(&existing_ref->lock);
 561 }
 562
 563 /*
 564  * helper function to actually insert a head node into the rbtree.
 565  * this does all the dirty work in terms of maintaining the correct
 566  * overall modification count.
 567  */
 568 static noinline struct btrfs_delayed_ref_head *
 569 add_delayed_ref_head(struct btrfs_fs_info *fs_info,
 570                      struct btrfs_trans_handle *trans,
 571                      struct btrfs_delayed_ref_node *ref, u64 bytenr,
 572                      u64 num_bytes, int action, int is_data)
 573 {
 574         struct btrfs_delayed_ref_head *existing;
 575         struct btrfs_delayed_ref_head *head_ref = NULL;
 576         struct btrfs_delayed_ref_root *delayed_refs;
 577         int count_mod = 1;
 578         int must_insert_reserved = 0;
 579
 580         /*
 581          * the head node stores the sum of all the mods, so dropping a ref
 582          * should drop the sum in the head node by one.
 583          */
 584         if (action == BTRFS_UPDATE_DELAYED_HEAD)
 585                 count_mod = 0;
 586         else if (action == BTRFS_DROP_DELAYED_REF)
 587                 count_mod = -1;
 588
 589         /*
 590          * BTRFS_ADD_DELAYED_EXTENT means that we need to update
 591          * the reserved accounting when the extent is finally added, or
 592          * if a later modification deletes the delayed ref without ever
 593          * inserting the extent into the extent allocation tree.
 594          * ref->must_insert_reserved is the flag used to record
 595          * that accounting mods are required.
 596          *
 597          * Once we record must_insert_reserved, switch the action to
 598          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
 599          */
 600         if (action == BTRFS_ADD_DELAYED_EXTENT)
 601                 must_insert_reserved = 1;
 602         else
 603                 must_insert_reserved = 0;
 604
 605         delayed_refs = &trans->transaction->delayed_refs;
 606
 607         /* first set the basic ref node struct up */
 608         atomic_set(&ref->refs, 1);
 609         ref->bytenr = bytenr;
 610         ref->num_bytes = num_bytes;
 611         ref->ref_mod = count_mod;
 612         ref->type  = 0;
 613         ref->action  = 0;
 614         ref->is_head = 1;
 615         ref->in_tree = 1;
 616         ref->seq = 0;
 617
 618         head_ref = btrfs_delayed_node_to_head(ref);
 619         head_ref->must_insert_reserved = must_insert_reserved;
 620         head_ref->is_data = is_data;
 621         head_ref->ref_root = RB_ROOT;
 622         head_ref->processing = 0;
 623         head_ref->total_ref_mod = count_mod;
 624
 625         spin_lock_init(&head_ref->lock);
 626         mutex_init(&head_ref->mutex);
 627
 628         trace_add_delayed_ref_head(ref, head_ref, action);
 629
 630         existing = htree_insert(&delayed_refs->href_root,
 631                                 &head_ref->href_node);
 632         if (existing) {
 633                 update_existing_head_ref(delayed_refs, &existing->node, ref);
 634                 /*
 635                  * we've updated the existing ref, free the newly
 636                  * allocated ref
 637                  */
 638                 kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 639                 head_ref = existing;
 640         } else {
 641                 if (is_data && count_mod < 0)
 642                         delayed_refs->pending_csums += num_bytes;
 643                 delayed_refs->num_heads++;
 644                 delayed_refs->num_heads_ready++;
 645                 atomic_inc(&delayed_refs->num_entries);
 646                 trans->delayed_ref_updates++;
 647         }
 648         return head_ref;
 649 }
 650
 651 /*
 652  * helper to insert a delayed tree ref into the rbtree.
 653  */
 654 static noinline void
 655 add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 656                      struct btrfs_trans_handle *trans,
 657                      struct btrfs_delayed_ref_head *head_ref,
 658                      struct btrfs_delayed_ref_node *ref, u64 bytenr,
 659                      u64 num_bytes, u64 parent, u64 ref_root, int level,
 660                      int action, int no_quota)
 661 {
 662         struct btrfs_delayed_ref_node *existing;
 663         struct btrfs_delayed_tree_ref *full_ref;
 664         struct btrfs_delayed_ref_root *delayed_refs;
 665         u64 seq = 0;
 666
 667         if (action == BTRFS_ADD_DELAYED_EXTENT)
 668                 action = BTRFS_ADD_DELAYED_REF;
 669
 670         if (is_fstree(ref_root))
 671                 seq = atomic64_read(&fs_info->tree_mod_seq);
 672         delayed_refs = &trans->transaction->delayed_refs;
 673
 674         /* first set the basic ref node struct up */
 675         atomic_set(&ref->refs, 1);
 676         ref->bytenr = bytenr;
 677         ref->num_bytes = num_bytes;
 678         ref->ref_mod = 1;
 679         ref->action = action;
 680         ref->is_head = 0;
 681         ref->in_tree = 1;
 682         ref->no_quota = no_quota;
 683         ref->seq = seq;
 684
 685         full_ref = btrfs_delayed_node_to_tree_ref(ref);
 686         full_ref->parent = parent;
 687         full_ref->root = ref_root;
 688         if (parent)
 689                 ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
 690         else
 691                 ref->type = BTRFS_TREE_BLOCK_REF_KEY;
 692         full_ref->level = level;
 693
 694         trace_add_delayed_tree_ref(ref, full_ref, action);
 695
 696         spin_lock(&head_ref->lock);
 697         existing = tree_insert(&head_ref->ref_root, &ref->rb_node);
 698         if (existing) {
 699                 update_existing_ref(trans, delayed_refs, head_ref, existing,
 700                                     ref);
 701                 /*
 702                  * we've updated the existing ref, free the newly
 703                  * allocated ref
 704                  */
 705                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, full_ref);
 706         } else {
 707                 atomic_inc(&delayed_refs->num_entries);
 708                 trans->delayed_ref_updates++;
 709         }
 710         spin_unlock(&head_ref->lock);
 711 }
 712
 713 /*
 714  * helper to insert a delayed data ref into the rbtree.
 715  */
 716 static noinline void
 717 add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 718                      struct btrfs_trans_handle *trans,
 719                      struct btrfs_delayed_ref_head *head_ref,
 720                      struct btrfs_delayed_ref_node *ref, u64 bytenr,
 721                      u64 num_bytes, u64 parent, u64 ref_root, u64 owner,
 722                      u64 offset, int action, int no_quota)
 723 {
 724         struct btrfs_delayed_ref_node *existing;
 725         struct btrfs_delayed_data_ref *full_ref;
 726         struct btrfs_delayed_ref_root *delayed_refs;
 727         u64 seq = 0;
 728
 729         if (action == BTRFS_ADD_DELAYED_EXTENT)
 730                 action = BTRFS_ADD_DELAYED_REF;
 731
 732         delayed_refs = &trans->transaction->delayed_refs;
 733
 734         if (is_fstree(ref_root))
 735                 seq = atomic64_read(&fs_info->tree_mod_seq);
 736
 737         /* first set the basic ref node struct up */
 738         atomic_set(&ref->refs, 1);
 739         ref->bytenr = bytenr;
 740         ref->num_bytes = num_bytes;
 741         ref->ref_mod = 1;
 742         ref->action = action;
 743         ref->is_head = 0;
 744         ref->in_tree = 1;
 745         ref->no_quota = no_quota;
 746         ref->seq = seq;
 747
 748         full_ref = btrfs_delayed_node_to_data_ref(ref);
 749         full_ref->parent = parent;
 750         full_ref->root = ref_root;
 751         if (parent)
 752                 ref->type = BTRFS_SHARED_DATA_REF_KEY;
 753         else
 754                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
 755
 756         full_ref->objectid = owner;
 757         full_ref->offset = offset;
 758
 759         trace_add_delayed_data_ref(ref, full_ref, action);
 760
 761         spin_lock(&head_ref->lock);
 762         existing = tree_insert(&head_ref->ref_root, &ref->rb_node);
 763         if (existing) {
 764                 update_existing_ref(trans, delayed_refs, head_ref, existing,
 765                                     ref);
 766                 /*
 767                  * we've updated the existing ref, free the newly
 768                  * allocated ref
 769                  */
 770                 kmem_cache_free(btrfs_delayed_data_ref_cachep, full_ref);
 771         } else {
 772                 atomic_inc(&delayed_refs->num_entries);
 773                 trans->delayed_ref_updates++;
 774         }
 775         spin_unlock(&head_ref->lock);
 776 }
 777
 778 /*
 779  * add a delayed tree ref.  This does all of the accounting required
 780  * to make sure the delayed ref is eventually processed before this
 781  * transaction commits.
 782  */
 783 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 784                                struct btrfs_trans_handle *trans,
 785                                u64 bytenr, u64 num_bytes, u64 parent,
 786                                u64 ref_root,  int level, int action,
 787                                struct btrfs_delayed_extent_op *extent_op,
 788                                int no_quota)
 789 {
 790         struct btrfs_delayed_tree_ref *ref;
 791         struct btrfs_delayed_ref_head *head_ref;
 792         struct btrfs_delayed_ref_root *delayed_refs;
 793
 794         if (!is_fstree(ref_root) || !fs_info->quota_enabled)
 795                 no_quota = 0;
 796
 797         BUG_ON(extent_op && extent_op->is_data);
 798         ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
 799         if (!ref)
 800                 return -ENOMEM;
 801
 802         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 803         if (!head_ref) {
 804                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 805                 return -ENOMEM;
 806         }
 807
 808         head_ref->extent_op = extent_op;
 809
 810         delayed_refs = &trans->transaction->delayed_refs;
 811         spin_lock(&delayed_refs->lock);
 812
 813         /*
 814          * insert both the head node and the new ref without dropping
 815          * the spin lock
 816          */
 817         head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node,
 818                                         bytenr, num_bytes, action, 0);
 819
 820         add_delayed_tree_ref(fs_info, trans, head_ref, &ref->node, bytenr,
 821                                    num_bytes, parent, ref_root, level, action,
 822                                    no_quota);
 823         spin_unlock(&delayed_refs->lock);
 824
 825         return 0;
 826 }
 827
 828 /*
 829  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 830  */
 831 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 832                                struct btrfs_trans_handle *trans,
 833                                u64 bytenr, u64 num_bytes,
 834                                u64 parent, u64 ref_root,
 835                                u64 owner, u64 offset, int action,
 836                                struct btrfs_delayed_extent_op *extent_op,
 837                                int no_quota)
 838 {
 839         struct btrfs_delayed_data_ref *ref;
 840         struct btrfs_delayed_ref_head *head_ref;
 841         struct btrfs_delayed_ref_root *delayed_refs;
 842
 843         if (!is_fstree(ref_root) || !fs_info->quota_enabled)
 844                 no_quota = 0;
 845
 846         BUG_ON(extent_op && !extent_op->is_data);
 847         ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
 848         if (!ref)
 849                 return -ENOMEM;
 850
 851         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 852         if (!head_ref) {
 853                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 854                 return -ENOMEM;
 855         }
 856
 857         head_ref->extent_op = extent_op;
 858
 859         delayed_refs = &trans->transaction->delayed_refs;
 860         spin_lock(&delayed_refs->lock);
 861
 862         /*
 863          * insert both the head node and the new ref without dropping
 864          * the spin lock
 865          */
 866         head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node,
 867                                         bytenr, num_bytes, action, 1);
 868
 869         add_delayed_data_ref(fs_info, trans, head_ref, &ref->node, bytenr,
 870                                    num_bytes, parent, ref_root, owner, offset,
 871                                    action, no_quota);
 872         spin_unlock(&delayed_refs->lock);
 873
 874         return 0;
 875 }
 876
 877 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 878                                 struct btrfs_trans_handle *trans,
 879                                 u64 bytenr, u64 num_bytes,
 880                                 struct btrfs_delayed_extent_op *extent_op)
 881 {
 882         struct btrfs_delayed_ref_head *head_ref;
 883         struct btrfs_delayed_ref_root *delayed_refs;
 884
 885         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 886         if (!head_ref)
 887                 return -ENOMEM;
 888
 889         head_ref->extent_op = extent_op;
 890
 891         delayed_refs = &trans->transaction->delayed_refs;
 892         spin_lock(&delayed_refs->lock);
 893
 894         add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
 895                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
 896                                    extent_op->is_data);
 897
 898         spin_unlock(&delayed_refs->lock);
 899         return 0;
 900 }
 901
 902 /*
 903  * this does a simple search for the head node for a given extent.
 904  * It must be called with the delayed ref spinlock held, and it returns
 905  * the head node if any where found, or NULL if not.
 906  */
 907 struct btrfs_delayed_ref_head *
 908 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
 909 {
 910         struct btrfs_delayed_ref_root *delayed_refs;
 911
 912         delayed_refs = &trans->transaction->delayed_refs;
 913         return find_ref_head(&delayed_refs->href_root, bytenr, 0);
 914 }
 915
 916 void btrfs_delayed_ref_exit(void)
 917 {
 918         if (btrfs_delayed_ref_head_cachep)
 919                 kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
 920         if (btrfs_delayed_tree_ref_cachep)
 921                 kmem_cache_destroy(btrfs_delayed_tree_ref_cachep);
 922         if (btrfs_delayed_data_ref_cachep)
 923                 kmem_cache_destroy(btrfs_delayed_data_ref_cachep);
 924         if (btrfs_delayed_extent_op_cachep)
 925                 kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
 926 }
 927
 928 int btrfs_delayed_ref_init(void)
 929 {
 930         btrfs_delayed_ref_head_cachep = kmem_cache_create(
 931                                 "btrfs_delayed_ref_head",
 932                                 sizeof(struct btrfs_delayed_ref_head), 0,
 933                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 934         if (!btrfs_delayed_ref_head_cachep)
 935                 goto fail;
 936
 937         btrfs_delayed_tree_ref_cachep = kmem_cache_create(
 938                                 "btrfs_delayed_tree_ref",
 939                                 sizeof(struct btrfs_delayed_tree_ref), 0,
 940                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 941         if (!btrfs_delayed_tree_ref_cachep)
 942                 goto fail;
 943
 944         btrfs_delayed_data_ref_cachep = kmem_cache_create(
 945                                 "btrfs_delayed_data_ref",
 946                                 sizeof(struct btrfs_delayed_data_ref), 0,
 947                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 948         if (!btrfs_delayed_data_ref_cachep)
 949                 goto fail;
 950
 951         btrfs_delayed_extent_op_cachep = kmem_cache_create(
 952                                 "btrfs_delayed_extent_op",
 953                                 sizeof(struct btrfs_delayed_extent_op), 0,
 954                                 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
 955         if (!btrfs_delayed_extent_op_cachep)
 956                 goto fail;
 957
 958         return 0;
 959 fail:
 960         btrfs_delayed_ref_exit();
 961         return -ENOMEM;
 962 }