fs/btrfs/delayed-ref.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2009 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/sched.h>
   7 #include <linux/slab.h>
   8 #include <linux/sort.h>
   9 #include "ctree.h"
  10 #include "delayed-ref.h"
  11 #include "transaction.h"
  12 #include "qgroup.h"
  13
  14 struct kmem_cache *btrfs_delayed_ref_head_cachep;
  15 struct kmem_cache *btrfs_delayed_tree_ref_cachep;
  16 struct kmem_cache *btrfs_delayed_data_ref_cachep;
  17 struct kmem_cache *btrfs_delayed_extent_op_cachep;
  18 /*
  19  * delayed back reference update tracking.  For subvolume trees
  20  * we queue up extent allocations and backref maintenance for
  21  * delayed processing.   This avoids deep call chains where we
  22  * add extents in the middle of btrfs_search_slot, and it allows
  23  * us to buffer up frequently modified backrefs in an rb tree instead
  24  * of hammering updates on the extent allocation tree.
  25  */
  26
  27 /*
  28  * compare two delayed tree backrefs with same bytenr and type
  29  */
  30 static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref1,
  31                           struct btrfs_delayed_tree_ref *ref2)
  32 {
  33         if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) {
  34                 if (ref1->root < ref2->root)
  35                         return -1;
  36                 if (ref1->root > ref2->root)
  37                         return 1;
  38         } else {
  39                 if (ref1->parent < ref2->parent)
  40                         return -1;
  41                 if (ref1->parent > ref2->parent)
  42                         return 1;
  43         }
  44         return 0;
  45 }
  46
  47 /*
  48  * compare two delayed data backrefs with same bytenr and type
  49  */
  50 static int comp_data_refs(struct btrfs_delayed_data_ref *ref1,
  51                           struct btrfs_delayed_data_ref *ref2)
  52 {
  53         if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
  54                 if (ref1->root < ref2->root)
  55                         return -1;
  56                 if (ref1->root > ref2->root)
  57                         return 1;
  58                 if (ref1->objectid < ref2->objectid)
  59                         return -1;
  60                 if (ref1->objectid > ref2->objectid)
  61                         return 1;
  62                 if (ref1->offset < ref2->offset)
  63                         return -1;
  64                 if (ref1->offset > ref2->offset)
  65                         return 1;
  66         } else {
  67                 if (ref1->parent < ref2->parent)
  68                         return -1;
  69                 if (ref1->parent > ref2->parent)
  70                         return 1;
  71         }
  72         return 0;
  73 }
  74
  75 static int comp_refs(struct btrfs_delayed_ref_node *ref1,
  76                      struct btrfs_delayed_ref_node *ref2,
  77                      bool check_seq)
  78 {
  79         int ret = 0;
  80
  81         if (ref1->type < ref2->type)
  82                 return -1;
  83         if (ref1->type > ref2->type)
  84                 return 1;
  85         if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
  86             ref1->type == BTRFS_SHARED_BLOCK_REF_KEY)
  87                 ret = comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref1),
  88                                      btrfs_delayed_node_to_tree_ref(ref2));
  89         else
  90                 ret = comp_data_refs(btrfs_delayed_node_to_data_ref(ref1),
  91                                      btrfs_delayed_node_to_data_ref(ref2));
  92         if (ret)
  93                 return ret;
  94         if (check_seq) {
  95                 if (ref1->seq < ref2->seq)
  96                         return -1;
  97                 if (ref1->seq > ref2->seq)
  98                         return 1;
  99         }
 100         return 0;
 101 }
 102
 103 /* insert a new ref to head ref rbtree */
 104 static struct btrfs_delayed_ref_head *htree_insert(struct rb_root_cached *root,
 105                                                    struct rb_node *node)
 106 {
 107         struct rb_node **p = &root->rb_root.rb_node;
 108         struct rb_node *parent_node = NULL;
 109         struct btrfs_delayed_ref_head *entry;
 110         struct btrfs_delayed_ref_head *ins;
 111         u64 bytenr;
 112         bool leftmost = true;
 113
 114         ins = rb_entry(node, struct btrfs_delayed_ref_head, href_node);
 115         bytenr = ins->bytenr;
 116         while (*p) {
 117                 parent_node = *p;
 118                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_head,
 119                                  href_node);
 120
 121                 if (bytenr < entry->bytenr) {
 122                         p = &(*p)->rb_left;
 123                 } else if (bytenr > entry->bytenr) {
 124                         p = &(*p)->rb_right;
 125                         leftmost = false;
 126                 } else {
 127                         return entry;
 128                 }
 129         }
 130
 131         rb_link_node(node, parent_node, p);
 132         rb_insert_color_cached(node, root, leftmost);
 133         return NULL;
 134 }
 135
 136 static struct btrfs_delayed_ref_node* tree_insert(struct rb_root_cached *root,
 137                 struct btrfs_delayed_ref_node *ins)
 138 {
 139         struct rb_node **p = &root->rb_root.rb_node;
 140         struct rb_node *node = &ins->ref_node;
 141         struct rb_node *parent_node = NULL;
 142         struct btrfs_delayed_ref_node *entry;
 143         bool leftmost = true;
 144
 145         while (*p) {
 146                 int comp;
 147
 148                 parent_node = *p;
 149                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
 150                                  ref_node);
 151                 comp = comp_refs(ins, entry, true);
 152                 if (comp < 0) {
 153                         p = &(*p)->rb_left;
 154                 } else if (comp > 0) {
 155                         p = &(*p)->rb_right;
 156                         leftmost = false;
 157                 } else {
 158                         return entry;
 159                 }
 160         }
 161
 162         rb_link_node(node, parent_node, p);
 163         rb_insert_color_cached(node, root, leftmost);
 164         return NULL;
 165 }
 166
 167 static struct btrfs_delayed_ref_head *find_first_ref_head(
 168                 struct btrfs_delayed_ref_root *dr)
 169 {
 170         struct rb_node *n;
 171         struct btrfs_delayed_ref_head *entry;
 172
 173         n = rb_first_cached(&dr->href_root);
 174         if (!n)
 175                 return NULL;
 176
 177         entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
 178
 179         return entry;
 180 }
 181
 182 /*
 183  * Find a head entry based on bytenr. This returns the delayed ref head if it
 184  * was able to find one, or NULL if nothing was in that spot.  If return_bigger
 185  * is given, the next bigger entry is returned if no exact match is found.
 186  */
 187 static struct btrfs_delayed_ref_head *find_ref_head(
 188                 struct btrfs_delayed_ref_root *dr, u64 bytenr,
 189                 bool return_bigger)
 190 {
 191         struct rb_root *root = &dr->href_root.rb_root;
 192         struct rb_node *n;
 193         struct btrfs_delayed_ref_head *entry;
 194
 195         n = root->rb_node;
 196         entry = NULL;
 197         while (n) {
 198                 entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
 199
 200                 if (bytenr < entry->bytenr)
 201                         n = n->rb_left;
 202                 else if (bytenr > entry->bytenr)
 203                         n = n->rb_right;
 204                 else
 205                         return entry;
 206         }
 207         if (entry && return_bigger) {
 208                 if (bytenr > entry->bytenr) {
 209                         n = rb_next(&entry->href_node);
 210                         if (!n)
 211                                 return NULL;
 212                         entry = rb_entry(n, struct btrfs_delayed_ref_head,
 213                                          href_node);
 214                 }
 215                 return entry;
 216         }
 217         return NULL;
 218 }
 219
 220 int btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,
 221                            struct btrfs_delayed_ref_head *head)
 222 {
 223         lockdep_assert_held(&delayed_refs->lock);
 224         if (mutex_trylock(&head->mutex))
 225                 return 0;
 226
 227         refcount_inc(&head->refs);
 228         spin_unlock(&delayed_refs->lock);
 229
 230         mutex_lock(&head->mutex);
 231         spin_lock(&delayed_refs->lock);
 232         if (RB_EMPTY_NODE(&head->href_node)) {
 233                 mutex_unlock(&head->mutex);
 234                 btrfs_put_delayed_ref_head(head);
 235                 return -EAGAIN;
 236         }
 237         btrfs_put_delayed_ref_head(head);
 238         return 0;
 239 }
 240
 241 static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
 242                                     struct btrfs_delayed_ref_root *delayed_refs,
 243                                     struct btrfs_delayed_ref_head *head,
 244                                     struct btrfs_delayed_ref_node *ref)
 245 {
 246         lockdep_assert_held(&head->lock);
 247         rb_erase_cached(&ref->ref_node, &head->ref_tree);
 248         RB_CLEAR_NODE(&ref->ref_node);
 249         if (!list_empty(&ref->add_list))
 250                 list_del(&ref->add_list);
 251         ref->in_tree = 0;
 252         btrfs_put_delayed_ref(ref);
 253         atomic_dec(&delayed_refs->num_entries);
 254         if (trans->delayed_ref_updates)
 255                 trans->delayed_ref_updates--;
 256 }
 257
 258 static bool merge_ref(struct btrfs_trans_handle *trans,
 259                       struct btrfs_delayed_ref_root *delayed_refs,
 260                       struct btrfs_delayed_ref_head *head,
 261                       struct btrfs_delayed_ref_node *ref,
 262                       u64 seq)
 263 {
 264         struct btrfs_delayed_ref_node *next;
 265         struct rb_node *node = rb_next(&ref->ref_node);
 266         bool done = false;
 267
 268         while (!done && node) {
 269                 int mod;
 270
 271                 next = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
 272                 node = rb_next(node);
 273                 if (seq && next->seq >= seq)
 274                         break;
 275                 if (comp_refs(ref, next, false))
 276                         break;
 277
 278                 if (ref->action == next->action) {
 279                         mod = next->ref_mod;
 280                 } else {
 281                         if (ref->ref_mod < next->ref_mod) {
 282                                 swap(ref, next);
 283                                 done = true;
 284                         }
 285                         mod = -next->ref_mod;
 286                 }
 287
 288                 drop_delayed_ref(trans, delayed_refs, head, next);
 289                 ref->ref_mod += mod;
 290                 if (ref->ref_mod == 0) {
 291                         drop_delayed_ref(trans, delayed_refs, head, ref);
 292                         done = true;
 293                 } else {
 294                         /*
 295                          * Can't have multiples of the same ref on a tree block.
 296                          */
 297                         WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
 298                                 ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
 299                 }
 300         }
 301
 302         return done;
 303 }
 304
 305 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 306                               struct btrfs_delayed_ref_root *delayed_refs,
 307                               struct btrfs_delayed_ref_head *head)
 308 {
 309         struct btrfs_fs_info *fs_info = trans->fs_info;
 310         struct btrfs_delayed_ref_node *ref;
 311         struct rb_node *node;
 312         u64 seq = 0;
 313
 314         lockdep_assert_held(&head->lock);
 315
 316         if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
 317                 return;
 318
 319         /* We don't have too many refs to merge for data. */
 320         if (head->is_data)
 321                 return;
 322
 323         spin_lock(&fs_info->tree_mod_seq_lock);
 324         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 325                 struct seq_list *elem;
 326
 327                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 328                                         struct seq_list, list);
 329                 seq = elem->seq;
 330         }
 331         spin_unlock(&fs_info->tree_mod_seq_lock);
 332
 333 again:
 334         for (node = rb_first_cached(&head->ref_tree); node;
 335              node = rb_next(node)) {
 336                 ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
 337                 if (seq && ref->seq >= seq)
 338                         continue;
 339                 if (merge_ref(trans, delayed_refs, head, ref, seq))
 340                         goto again;
 341         }
 342 }
 343
 344 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq)
 345 {
 346         struct seq_list *elem;
 347         int ret = 0;
 348
 349         spin_lock(&fs_info->tree_mod_seq_lock);
 350         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 351                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 352                                         struct seq_list, list);
 353                 if (seq >= elem->seq) {
 354                         btrfs_debug(fs_info,
 355                                 "holding back delayed_ref %#x.%x, lowest is %#x.%x",
 356                                 (u32)(seq >> 32), (u32)seq,
 357                                 (u32)(elem->seq >> 32), (u32)elem->seq);
 358                         ret = 1;
 359                 }
 360         }
 361
 362         spin_unlock(&fs_info->tree_mod_seq_lock);
 363         return ret;
 364 }
 365
 366 struct btrfs_delayed_ref_head *btrfs_select_ref_head(
 367                 struct btrfs_delayed_ref_root *delayed_refs)
 368 {
 369         struct btrfs_delayed_ref_head *head;
 370
 371 again:
 372         head = find_ref_head(delayed_refs, delayed_refs->run_delayed_start,
 373                              true);
 374         if (!head && delayed_refs->run_delayed_start != 0) {
 375                 delayed_refs->run_delayed_start = 0;
 376                 head = find_first_ref_head(delayed_refs);
 377         }
 378         if (!head)
 379                 return NULL;
 380
 381         while (head->processing) {
 382                 struct rb_node *node;
 383
 384                 node = rb_next(&head->href_node);
 385                 if (!node) {
 386                         if (delayed_refs->run_delayed_start == 0)
 387                                 return NULL;
 388                         delayed_refs->run_delayed_start = 0;
 389                         goto again;
 390                 }
 391                 head = rb_entry(node, struct btrfs_delayed_ref_head,
 392                                 href_node);
 393         }
 394
 395         head->processing = 1;
 396         WARN_ON(delayed_refs->num_heads_ready == 0);
 397         delayed_refs->num_heads_ready--;
 398         delayed_refs->run_delayed_start = head->bytenr +
 399                 head->num_bytes;
 400         return head;
 401 }
 402
 403 /*
 404  * Helper to insert the ref_node to the tail or merge with tail.
 405  *
 406  * Return 0 for insert.
 407  * Return >0 for merge.
 408  */
 409 static int insert_delayed_ref(struct btrfs_trans_handle *trans,
 410                               struct btrfs_delayed_ref_root *root,
 411                               struct btrfs_delayed_ref_head *href,
 412                               struct btrfs_delayed_ref_node *ref)
 413 {
 414         struct btrfs_delayed_ref_node *exist;
 415         int mod;
 416         int ret = 0;
 417
 418         spin_lock(&href->lock);
 419         exist = tree_insert(&href->ref_tree, ref);
 420         if (!exist)
 421                 goto inserted;
 422
 423         /* Now we are sure we can merge */
 424         ret = 1;
 425         if (exist->action == ref->action) {
 426                 mod = ref->ref_mod;
 427         } else {
 428                 /* Need to change action */
 429                 if (exist->ref_mod < ref->ref_mod) {
 430                         exist->action = ref->action;
 431                         mod = -exist->ref_mod;
 432                         exist->ref_mod = ref->ref_mod;
 433                         if (ref->action == BTRFS_ADD_DELAYED_REF)
 434                                 list_add_tail(&exist->add_list,
 435                                               &href->ref_add_list);
 436                         else if (ref->action == BTRFS_DROP_DELAYED_REF) {
 437                                 ASSERT(!list_empty(&exist->add_list));
 438                                 list_del(&exist->add_list);
 439                         } else {
 440                                 ASSERT(0);
 441                         }
 442                 } else
 443                         mod = -ref->ref_mod;
 444         }
 445         exist->ref_mod += mod;
 446
 447         /* remove existing tail if its ref_mod is zero */
 448         if (exist->ref_mod == 0)
 449                 drop_delayed_ref(trans, root, href, exist);
 450         spin_unlock(&href->lock);
 451         return ret;
 452 inserted:
 453         if (ref->action == BTRFS_ADD_DELAYED_REF)
 454                 list_add_tail(&ref->add_list, &href->ref_add_list);
 455         atomic_inc(&root->num_entries);
 456         trans->delayed_ref_updates++;
 457         spin_unlock(&href->lock);
 458         return ret;
 459 }
 460
 461 /*
 462  * helper function to update the accounting in the head ref
 463  * existing and update must have the same bytenr
 464  */
 465 static noinline void
 466 update_existing_head_ref(struct btrfs_delayed_ref_root *delayed_refs,
 467                          struct btrfs_delayed_ref_head *existing,
 468                          struct btrfs_delayed_ref_head *update,
 469                          int *old_ref_mod_ret)
 470 {
 471         int old_ref_mod;
 472
 473         BUG_ON(existing->is_data != update->is_data);
 474
 475         spin_lock(&existing->lock);
 476         if (update->must_insert_reserved) {
 477                 /* if the extent was freed and then
 478                  * reallocated before the delayed ref
 479                  * entries were processed, we can end up
 480                  * with an existing head ref without
 481                  * the must_insert_reserved flag set.
 482                  * Set it again here
 483                  */
 484                 existing->must_insert_reserved = update->must_insert_reserved;
 485
 486                 /*
 487                  * update the num_bytes so we make sure the accounting
 488                  * is done correctly
 489                  */
 490                 existing->num_bytes = update->num_bytes;
 491
 492         }
 493
 494         if (update->extent_op) {
 495                 if (!existing->extent_op) {
 496                         existing->extent_op = update->extent_op;
 497                 } else {
 498                         if (update->extent_op->update_key) {
 499                                 memcpy(&existing->extent_op->key,
 500                                        &update->extent_op->key,
 501                                        sizeof(update->extent_op->key));
 502                                 existing->extent_op->update_key = true;
 503                         }
 504                         if (update->extent_op->update_flags) {
 505                                 existing->extent_op->flags_to_set |=
 506                                         update->extent_op->flags_to_set;
 507                                 existing->extent_op->update_flags = true;
 508                         }
 509                         btrfs_free_delayed_extent_op(update->extent_op);
 510                 }
 511         }
 512         /*
 513          * update the reference mod on the head to reflect this new operation,
 514          * only need the lock for this case cause we could be processing it
 515          * currently, for refs we just added we know we're a-ok.
 516          */
 517         old_ref_mod = existing->total_ref_mod;
 518         if (old_ref_mod_ret)
 519                 *old_ref_mod_ret = old_ref_mod;
 520         existing->ref_mod += update->ref_mod;
 521         existing->total_ref_mod += update->ref_mod;
 522
 523         /*
 524          * If we are going to from a positive ref mod to a negative or vice
 525          * versa we need to make sure to adjust pending_csums accordingly.
 526          */
 527         if (existing->is_data) {
 528                 if (existing->total_ref_mod >= 0 && old_ref_mod < 0)
 529                         delayed_refs->pending_csums -= existing->num_bytes;
 530                 if (existing->total_ref_mod < 0 && old_ref_mod >= 0)
 531                         delayed_refs->pending_csums += existing->num_bytes;
 532         }
 533         spin_unlock(&existing->lock);
 534 }
 535
 536 static void init_delayed_ref_head(struct btrfs_delayed_ref_head *head_ref,
 537                                   struct btrfs_qgroup_extent_record *qrecord,
 538                                   u64 bytenr, u64 num_bytes, u64 ref_root,
 539                                   u64 reserved, int action, bool is_data,
 540                                   bool is_system)
 541 {
 542         int count_mod = 1;
 543         int must_insert_reserved = 0;
 544
 545         /* If reserved is provided, it must be a data extent. */
 546         BUG_ON(!is_data && reserved);
 547
 548         /*
 549          * The head node stores the sum of all the mods, so dropping a ref
 550          * should drop the sum in the head node by one.
 551          */
 552         if (action == BTRFS_UPDATE_DELAYED_HEAD)
 553                 count_mod = 0;
 554         else if (action == BTRFS_DROP_DELAYED_REF)
 555                 count_mod = -1;
 556
 557         /*
 558          * BTRFS_ADD_DELAYED_EXTENT means that we need to update the reserved
 559          * accounting when the extent is finally added, or if a later
 560          * modification deletes the delayed ref without ever inserting the
 561          * extent into the extent allocation tree.  ref->must_insert_reserved
 562          * is the flag used to record that accounting mods are required.
 563          *
 564          * Once we record must_insert_reserved, switch the action to
 565          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
 566          */
 567         if (action == BTRFS_ADD_DELAYED_EXTENT)
 568                 must_insert_reserved = 1;
 569         else
 570                 must_insert_reserved = 0;
 571
 572         refcount_set(&head_ref->refs, 1);
 573         head_ref->bytenr = bytenr;
 574         head_ref->num_bytes = num_bytes;
 575         head_ref->ref_mod = count_mod;
 576         head_ref->must_insert_reserved = must_insert_reserved;
 577         head_ref->is_data = is_data;
 578         head_ref->is_system = is_system;
 579         head_ref->ref_tree = RB_ROOT_CACHED;
 580         INIT_LIST_HEAD(&head_ref->ref_add_list);
 581         RB_CLEAR_NODE(&head_ref->href_node);
 582         head_ref->processing = 0;
 583         head_ref->total_ref_mod = count_mod;
 584         head_ref->qgroup_reserved = 0;
 585         head_ref->qgroup_ref_root = 0;
 586         spin_lock_init(&head_ref->lock);
 587         mutex_init(&head_ref->mutex);
 588
 589         if (qrecord) {
 590                 if (ref_root && reserved) {
 591                         head_ref->qgroup_ref_root = ref_root;
 592                         head_ref->qgroup_reserved = reserved;
 593                 }
 594
 595                 qrecord->bytenr = bytenr;
 596                 qrecord->num_bytes = num_bytes;
 597                 qrecord->old_roots = NULL;
 598         }
 599 }
 600
 601 /*
 602  * helper function to actually insert a head node into the rbtree.
 603  * this does all the dirty work in terms of maintaining the correct
 604  * overall modification count.
 605  */
 606 static noinline struct btrfs_delayed_ref_head *
 607 add_delayed_ref_head(struct btrfs_trans_handle *trans,
 608                      struct btrfs_delayed_ref_head *head_ref,
 609                      struct btrfs_qgroup_extent_record *qrecord,
 610                      int action, int *qrecord_inserted_ret,
 611                      int *old_ref_mod, int *new_ref_mod)
 612 {
 613         struct btrfs_delayed_ref_head *existing;
 614         struct btrfs_delayed_ref_root *delayed_refs;
 615         int qrecord_inserted = 0;
 616
 617         delayed_refs = &trans->transaction->delayed_refs;
 618
 619         /* Record qgroup extent info if provided */
 620         if (qrecord) {
 621                 if (btrfs_qgroup_trace_extent_nolock(trans->fs_info,
 622                                         delayed_refs, qrecord))
 623                         kfree(qrecord);
 624                 else
 625                         qrecord_inserted = 1;
 626         }
 627
 628         trace_add_delayed_ref_head(trans->fs_info, head_ref, action);
 629
 630         existing = htree_insert(&delayed_refs->href_root,
 631                                 &head_ref->href_node);
 632         if (existing) {
 633                 WARN_ON(qrecord && head_ref->qgroup_ref_root
 634                         && head_ref->qgroup_reserved
 635                         && existing->qgroup_ref_root
 636                         && existing->qgroup_reserved);
 637                 update_existing_head_ref(delayed_refs, existing, head_ref,
 638                                          old_ref_mod);
 639                 /*
 640                  * we've updated the existing ref, free the newly
 641                  * allocated ref
 642                  */
 643                 kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 644                 head_ref = existing;
 645         } else {
 646                 if (old_ref_mod)
 647                         *old_ref_mod = 0;
 648                 if (head_ref->is_data && head_ref->ref_mod < 0)
 649                         delayed_refs->pending_csums += head_ref->num_bytes;
 650                 delayed_refs->num_heads++;
 651                 delayed_refs->num_heads_ready++;
 652                 atomic_inc(&delayed_refs->num_entries);
 653                 trans->delayed_ref_updates++;
 654         }
 655         if (qrecord_inserted_ret)
 656                 *qrecord_inserted_ret = qrecord_inserted;
 657         if (new_ref_mod)
 658                 *new_ref_mod = head_ref->total_ref_mod;
 659
 660         return head_ref;
 661 }
 662
 663 /*
 664  * init_delayed_ref_common - Initialize the structure which represents a
 665  *                           modification to a an extent.
 666  *
 667  * @fs_info:    Internal to the mounted filesystem mount structure.
 668  *
 669  * @ref:        The structure which is going to be initialized.
 670  *
 671  * @bytenr:     The logical address of the extent for which a modification is
 672  *              going to be recorded.
 673  *
 674  * @num_bytes:  Size of the extent whose modification is being recorded.
 675  *
 676  * @ref_root:   The id of the root where this modification has originated, this
 677  *              can be either one of the well-known metadata trees or the
 678  *              subvolume id which references this extent.
 679  *
 680  * @action:     Can be one of BTRFS_ADD_DELAYED_REF/BTRFS_DROP_DELAYED_REF or
 681  *              BTRFS_ADD_DELAYED_EXTENT
 682  *
 683  * @ref_type:   Holds the type of the extent which is being recorded, can be
 684  *              one of BTRFS_SHARED_BLOCK_REF_KEY/BTRFS_TREE_BLOCK_REF_KEY
 685  *              when recording a metadata extent or BTRFS_SHARED_DATA_REF_KEY/
 686  *              BTRFS_EXTENT_DATA_REF_KEY when recording data extent
 687  */
 688 static void init_delayed_ref_common(struct btrfs_fs_info *fs_info,
 689                                     struct btrfs_delayed_ref_node *ref,
 690                                     u64 bytenr, u64 num_bytes, u64 ref_root,
 691                                     int action, u8 ref_type)
 692 {
 693         u64 seq = 0;
 694
 695         if (action == BTRFS_ADD_DELAYED_EXTENT)
 696                 action = BTRFS_ADD_DELAYED_REF;
 697
 698         if (is_fstree(ref_root))
 699                 seq = atomic64_read(&fs_info->tree_mod_seq);
 700
 701         refcount_set(&ref->refs, 1);
 702         ref->bytenr = bytenr;
 703         ref->num_bytes = num_bytes;
 704         ref->ref_mod = 1;
 705         ref->action = action;
 706         ref->is_head = 0;
 707         ref->in_tree = 1;
 708         ref->seq = seq;
 709         ref->type = ref_type;
 710         RB_CLEAR_NODE(&ref->ref_node);
 711         INIT_LIST_HEAD(&ref->add_list);
 712 }
 713
 714 /*
 715  * add a delayed tree ref.  This does all of the accounting required
 716  * to make sure the delayed ref is eventually processed before this
 717  * transaction commits.
 718  */
 719 int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 720                                u64 bytenr, u64 num_bytes, u64 parent,
 721                                u64 ref_root,  int level, int action,
 722                                struct btrfs_delayed_extent_op *extent_op,
 723                                int *old_ref_mod, int *new_ref_mod)
 724 {
 725         struct btrfs_fs_info *fs_info = trans->fs_info;
 726         struct btrfs_delayed_tree_ref *ref;
 727         struct btrfs_delayed_ref_head *head_ref;
 728         struct btrfs_delayed_ref_root *delayed_refs;
 729         struct btrfs_qgroup_extent_record *record = NULL;
 730         int qrecord_inserted;
 731         bool is_system = (ref_root == BTRFS_CHUNK_TREE_OBJECTID);
 732         int ret;
 733         u8 ref_type;
 734
 735         BUG_ON(extent_op && extent_op->is_data);
 736         ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
 737         if (!ref)
 738                 return -ENOMEM;
 739
 740         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 741         if (!head_ref) {
 742                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 743                 return -ENOMEM;
 744         }
 745
 746         if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
 747             is_fstree(ref_root)) {
 748                 record = kmalloc(sizeof(*record), GFP_NOFS);
 749                 if (!record) {
 750                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 751                         kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 752                         return -ENOMEM;
 753                 }
 754         }
 755
 756         if (parent)
 757                 ref_type = BTRFS_SHARED_BLOCK_REF_KEY;
 758         else
 759                 ref_type = BTRFS_TREE_BLOCK_REF_KEY;
 760
 761         init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
 762                                 ref_root, action, ref_type);
 763         ref->root = ref_root;
 764         ref->parent = parent;
 765         ref->level = level;
 766
 767         init_delayed_ref_head(head_ref, record, bytenr, num_bytes,
 768                               ref_root, 0, action, false, is_system);
 769         head_ref->extent_op = extent_op;
 770
 771         delayed_refs = &trans->transaction->delayed_refs;
 772         spin_lock(&delayed_refs->lock);
 773
 774         /*
 775          * insert both the head node and the new ref without dropping
 776          * the spin lock
 777          */
 778         head_ref = add_delayed_ref_head(trans, head_ref, record,
 779                                         action, &qrecord_inserted,
 780                                         old_ref_mod, new_ref_mod);
 781
 782         ret = insert_delayed_ref(trans, delayed_refs, head_ref, &ref->node);
 783         spin_unlock(&delayed_refs->lock);
 784
 785         trace_add_delayed_tree_ref(fs_info, &ref->node, ref,
 786                                    action == BTRFS_ADD_DELAYED_EXTENT ?
 787                                    BTRFS_ADD_DELAYED_REF : action);
 788         if (ret > 0)
 789                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 790
 791         if (qrecord_inserted)
 792                 btrfs_qgroup_trace_extent_post(fs_info, record);
 793
 794         return 0;
 795 }
 796
 797 /*
 798  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 799  */
 800 int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 801                                u64 bytenr, u64 num_bytes,
 802                                u64 parent, u64 ref_root,
 803                                u64 owner, u64 offset, u64 reserved, int action,
 804                                int *old_ref_mod, int *new_ref_mod)
 805 {
 806         struct btrfs_fs_info *fs_info = trans->fs_info;
 807         struct btrfs_delayed_data_ref *ref;
 808         struct btrfs_delayed_ref_head *head_ref;
 809         struct btrfs_delayed_ref_root *delayed_refs;
 810         struct btrfs_qgroup_extent_record *record = NULL;
 811         int qrecord_inserted;
 812         int ret;
 813         u8 ref_type;
 814
 815         ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
 816         if (!ref)
 817                 return -ENOMEM;
 818
 819         if (parent)
 820                 ref_type = BTRFS_SHARED_DATA_REF_KEY;
 821         else
 822                 ref_type = BTRFS_EXTENT_DATA_REF_KEY;
 823         init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
 824                                 ref_root, action, ref_type);
 825         ref->root = ref_root;
 826         ref->parent = parent;
 827         ref->objectid = owner;
 828         ref->offset = offset;
 829
 830
 831         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 832         if (!head_ref) {
 833                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 834                 return -ENOMEM;
 835         }
 836
 837         if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
 838             is_fstree(ref_root)) {
 839                 record = kmalloc(sizeof(*record), GFP_NOFS);
 840                 if (!record) {
 841                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 842                         kmem_cache_free(btrfs_delayed_ref_head_cachep,
 843                                         head_ref);
 844                         return -ENOMEM;
 845                 }
 846         }
 847
 848         init_delayed_ref_head(head_ref, record, bytenr, num_bytes, ref_root,
 849                               reserved, action, true, false);
 850         head_ref->extent_op = NULL;
 851
 852         delayed_refs = &trans->transaction->delayed_refs;
 853         spin_lock(&delayed_refs->lock);
 854
 855         /*
 856          * insert both the head node and the new ref without dropping
 857          * the spin lock
 858          */
 859         head_ref = add_delayed_ref_head(trans, head_ref, record,
 860                                         action, &qrecord_inserted,
 861                                         old_ref_mod, new_ref_mod);
 862
 863         ret = insert_delayed_ref(trans, delayed_refs, head_ref, &ref->node);
 864         spin_unlock(&delayed_refs->lock);
 865
 866         trace_add_delayed_data_ref(trans->fs_info, &ref->node, ref,
 867                                    action == BTRFS_ADD_DELAYED_EXTENT ?
 868                                    BTRFS_ADD_DELAYED_REF : action);
 869         if (ret > 0)
 870                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 871
 872
 873         if (qrecord_inserted)
 874                 return btrfs_qgroup_trace_extent_post(fs_info, record);
 875         return 0;
 876 }
 877
 878 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 879                                 struct btrfs_trans_handle *trans,
 880                                 u64 bytenr, u64 num_bytes,
 881                                 struct btrfs_delayed_extent_op *extent_op)
 882 {
 883         struct btrfs_delayed_ref_head *head_ref;
 884         struct btrfs_delayed_ref_root *delayed_refs;
 885
 886         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 887         if (!head_ref)
 888                 return -ENOMEM;
 889
 890         init_delayed_ref_head(head_ref, NULL, bytenr, num_bytes, 0, 0,
 891                               BTRFS_UPDATE_DELAYED_HEAD, extent_op->is_data,
 892                               false);
 893         head_ref->extent_op = extent_op;
 894
 895         delayed_refs = &trans->transaction->delayed_refs;
 896         spin_lock(&delayed_refs->lock);
 897
 898         add_delayed_ref_head(trans, head_ref, NULL, BTRFS_UPDATE_DELAYED_HEAD,
 899                              NULL, NULL, NULL);
 900
 901         spin_unlock(&delayed_refs->lock);
 902         return 0;
 903 }
 904
 905 /*
 906  * this does a simple search for the head node for a given extent.
 907  * It must be called with the delayed ref spinlock held, and it returns
 908  * the head node if any where found, or NULL if not.
 909  */
 910 struct btrfs_delayed_ref_head *
 911 btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 bytenr)
 912 {
 913         return find_ref_head(delayed_refs, bytenr, false);
 914 }
 915
 916 void __cold btrfs_delayed_ref_exit(void)
 917 {
 918         kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
 919         kmem_cache_destroy(btrfs_delayed_tree_ref_cachep);
 920         kmem_cache_destroy(btrfs_delayed_data_ref_cachep);
 921         kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
 922 }
 923
 924 int __init btrfs_delayed_ref_init(void)
 925 {
 926         btrfs_delayed_ref_head_cachep = kmem_cache_create(
 927                                 "btrfs_delayed_ref_head",
 928                                 sizeof(struct btrfs_delayed_ref_head), 0,
 929                                 SLAB_MEM_SPREAD, NULL);
 930         if (!btrfs_delayed_ref_head_cachep)
 931                 goto fail;
 932
 933         btrfs_delayed_tree_ref_cachep = kmem_cache_create(
 934                                 "btrfs_delayed_tree_ref",
 935                                 sizeof(struct btrfs_delayed_tree_ref), 0,
 936                                 SLAB_MEM_SPREAD, NULL);
 937         if (!btrfs_delayed_tree_ref_cachep)
 938                 goto fail;
 939
 940         btrfs_delayed_data_ref_cachep = kmem_cache_create(
 941                                 "btrfs_delayed_data_ref",
 942                                 sizeof(struct btrfs_delayed_data_ref), 0,
 943                                 SLAB_MEM_SPREAD, NULL);
 944         if (!btrfs_delayed_data_ref_cachep)
 945                 goto fail;
 946
 947         btrfs_delayed_extent_op_cachep = kmem_cache_create(
 948                                 "btrfs_delayed_extent_op",
 949                                 sizeof(struct btrfs_delayed_extent_op), 0,
 950                                 SLAB_MEM_SPREAD, NULL);
 951         if (!btrfs_delayed_extent_op_cachep)
 952                 goto fail;
 953
 954         return 0;
 955 fail:
 956         btrfs_delayed_ref_exit();
 957         return -ENOMEM;
 958 }