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