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 }
 255
 256 static bool merge_ref(struct btrfs_trans_handle *trans,
 257                       struct btrfs_delayed_ref_root *delayed_refs,
 258                       struct btrfs_delayed_ref_head *head,
 259                       struct btrfs_delayed_ref_node *ref,
 260                       u64 seq)
 261 {
 262         struct btrfs_delayed_ref_node *next;
 263         struct rb_node *node = rb_next(&ref->ref_node);
 264         bool done = false;
 265
 266         while (!done && node) {
 267                 int mod;
 268
 269                 next = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
 270                 node = rb_next(node);
 271                 if (seq && next->seq >= seq)
 272                         break;
 273                 if (comp_refs(ref, next, false))
 274                         break;
 275
 276                 if (ref->action == next->action) {
 277                         mod = next->ref_mod;
 278                 } else {
 279                         if (ref->ref_mod < next->ref_mod) {
 280                                 swap(ref, next);
 281                                 done = true;
 282                         }
 283                         mod = -next->ref_mod;
 284                 }
 285
 286                 drop_delayed_ref(trans, delayed_refs, head, next);
 287                 ref->ref_mod += mod;
 288                 if (ref->ref_mod == 0) {
 289                         drop_delayed_ref(trans, delayed_refs, head, ref);
 290                         done = true;
 291                 } else {
 292                         /*
 293                          * Can't have multiples of the same ref on a tree block.
 294                          */
 295                         WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
 296                                 ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
 297                 }
 298         }
 299
 300         return done;
 301 }
 302
 303 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 304                               struct btrfs_delayed_ref_root *delayed_refs,
 305                               struct btrfs_delayed_ref_head *head)
 306 {
 307         struct btrfs_fs_info *fs_info = trans->fs_info;
 308         struct btrfs_delayed_ref_node *ref;
 309         struct rb_node *node;
 310         u64 seq = 0;
 311
 312         lockdep_assert_held(&head->lock);
 313
 314         if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
 315                 return;
 316
 317         /* We don't have too many refs to merge for data. */
 318         if (head->is_data)
 319                 return;
 320
 321         spin_lock(&fs_info->tree_mod_seq_lock);
 322         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 323                 struct seq_list *elem;
 324
 325                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 326                                         struct seq_list, list);
 327                 seq = elem->seq;
 328         }
 329         spin_unlock(&fs_info->tree_mod_seq_lock);
 330
 331 again:
 332         for (node = rb_first_cached(&head->ref_tree); node;
 333              node = rb_next(node)) {
 334                 ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
 335                 if (seq && ref->seq >= seq)
 336                         continue;
 337                 if (merge_ref(trans, delayed_refs, head, ref, seq))
 338                         goto again;
 339         }
 340 }
 341
 342 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq)
 343 {
 344         struct seq_list *elem;
 345         int ret = 0;
 346
 347         spin_lock(&fs_info->tree_mod_seq_lock);
 348         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 349                 elem = list_first_entry(&fs_info->tree_mod_seq_list,
 350                                         struct seq_list, list);
 351                 if (seq >= elem->seq) {
 352                         btrfs_debug(fs_info,
 353                                 "holding back delayed_ref %#x.%x, lowest is %#x.%x",
 354                                 (u32)(seq >> 32), (u32)seq,
 355                                 (u32)(elem->seq >> 32), (u32)elem->seq);
 356                         ret = 1;
 357                 }
 358         }
 359
 360         spin_unlock(&fs_info->tree_mod_seq_lock);
 361         return ret;
 362 }
 363
 364 struct btrfs_delayed_ref_head *btrfs_select_ref_head(
 365                 struct btrfs_delayed_ref_root *delayed_refs)
 366 {
 367         struct btrfs_delayed_ref_head *head;
 368
 369 again:
 370         head = find_ref_head(delayed_refs, delayed_refs->run_delayed_start,
 371                              true);
 372         if (!head && delayed_refs->run_delayed_start != 0) {
 373                 delayed_refs->run_delayed_start = 0;
 374                 head = find_first_ref_head(delayed_refs);
 375         }
 376         if (!head)
 377                 return NULL;
 378
 379         while (head->processing) {
 380                 struct rb_node *node;
 381
 382                 node = rb_next(&head->href_node);
 383                 if (!node) {
 384                         if (delayed_refs->run_delayed_start == 0)
 385                                 return NULL;
 386                         delayed_refs->run_delayed_start = 0;
 387                         goto again;
 388                 }
 389                 head = rb_entry(node, struct btrfs_delayed_ref_head,
 390                                 href_node);
 391         }
 392
 393         head->processing = 1;
 394         WARN_ON(delayed_refs->num_heads_ready == 0);
 395         delayed_refs->num_heads_ready--;
 396         delayed_refs->run_delayed_start = head->bytenr +
 397                 head->num_bytes;
 398         return head;
 399 }
 400
 401 void btrfs_delete_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 402                            struct btrfs_delayed_ref_head *head)
 403 {
 404         lockdep_assert_held(&delayed_refs->lock);
 405         lockdep_assert_held(&head->lock);
 406
 407         rb_erase_cached(&head->href_node, &delayed_refs->href_root);
 408         RB_CLEAR_NODE(&head->href_node);
 409         atomic_dec(&delayed_refs->num_entries);
 410         delayed_refs->num_heads--;
 411         if (head->processing == 0)
 412                 delayed_refs->num_heads_ready--;
 413 }
 414
 415 /*
 416  * Helper to insert the ref_node to the tail or merge with tail.
 417  *
 418  * Return 0 for insert.
 419  * Return >0 for merge.
 420  */
 421 static int insert_delayed_ref(struct btrfs_trans_handle *trans,
 422                               struct btrfs_delayed_ref_root *root,
 423                               struct btrfs_delayed_ref_head *href,
 424                               struct btrfs_delayed_ref_node *ref)
 425 {
 426         struct btrfs_delayed_ref_node *exist;
 427         int mod;
 428         int ret = 0;
 429
 430         spin_lock(&href->lock);
 431         exist = tree_insert(&href->ref_tree, ref);
 432         if (!exist)
 433                 goto inserted;
 434
 435         /* Now we are sure we can merge */
 436         ret = 1;
 437         if (exist->action == ref->action) {
 438                 mod = ref->ref_mod;
 439         } else {
 440                 /* Need to change action */
 441                 if (exist->ref_mod < ref->ref_mod) {
 442                         exist->action = ref->action;
 443                         mod = -exist->ref_mod;
 444                         exist->ref_mod = ref->ref_mod;
 445                         if (ref->action == BTRFS_ADD_DELAYED_REF)
 446                                 list_add_tail(&exist->add_list,
 447                                               &href->ref_add_list);
 448                         else if (ref->action == BTRFS_DROP_DELAYED_REF) {
 449                                 ASSERT(!list_empty(&exist->add_list));
 450                                 list_del(&exist->add_list);
 451                         } else {
 452                                 ASSERT(0);
 453                         }
 454                 } else
 455                         mod = -ref->ref_mod;
 456         }
 457         exist->ref_mod += mod;
 458
 459         /* remove existing tail if its ref_mod is zero */
 460         if (exist->ref_mod == 0)
 461                 drop_delayed_ref(trans, root, href, exist);
 462         spin_unlock(&href->lock);
 463         return ret;
 464 inserted:
 465         if (ref->action == BTRFS_ADD_DELAYED_REF)
 466                 list_add_tail(&ref->add_list, &href->ref_add_list);
 467         atomic_inc(&root->num_entries);
 468         spin_unlock(&href->lock);
 469         return ret;
 470 }
 471
 472 /*
 473  * helper function to update the accounting in the head ref
 474  * existing and update must have the same bytenr
 475  */
 476 static noinline void update_existing_head_ref(struct btrfs_trans_handle *trans,
 477                          struct btrfs_delayed_ref_head *existing,
 478                          struct btrfs_delayed_ref_head *update,
 479                          int *old_ref_mod_ret)
 480 {
 481         struct btrfs_delayed_ref_root *delayed_refs =
 482                 &trans->transaction->delayed_refs;
 483         struct btrfs_fs_info *fs_info = trans->fs_info;
 484         int old_ref_mod;
 485
 486         BUG_ON(existing->is_data != update->is_data);
 487
 488         spin_lock(&existing->lock);
 489         if (update->must_insert_reserved) {
 490                 /* if the extent was freed and then
 491                  * reallocated before the delayed ref
 492                  * entries were processed, we can end up
 493                  * with an existing head ref without
 494                  * the must_insert_reserved flag set.
 495                  * Set it again here
 496                  */
 497                 existing->must_insert_reserved = update->must_insert_reserved;
 498
 499                 /*
 500                  * update the num_bytes so we make sure the accounting
 501                  * is done correctly
 502                  */
 503                 existing->num_bytes = update->num_bytes;
 504
 505         }
 506
 507         if (update->extent_op) {
 508                 if (!existing->extent_op) {
 509                         existing->extent_op = update->extent_op;
 510                 } else {
 511                         if (update->extent_op->update_key) {
 512                                 memcpy(&existing->extent_op->key,
 513                                        &update->extent_op->key,
 514                                        sizeof(update->extent_op->key));
 515                                 existing->extent_op->update_key = true;
 516                         }
 517                         if (update->extent_op->update_flags) {
 518                                 existing->extent_op->flags_to_set |=
 519                                         update->extent_op->flags_to_set;
 520                                 existing->extent_op->update_flags = true;
 521                         }
 522                         btrfs_free_delayed_extent_op(update->extent_op);
 523                 }
 524         }
 525         /*
 526          * update the reference mod on the head to reflect this new operation,
 527          * only need the lock for this case cause we could be processing it
 528          * currently, for refs we just added we know we're a-ok.
 529          */
 530         old_ref_mod = existing->total_ref_mod;
 531         if (old_ref_mod_ret)
 532                 *old_ref_mod_ret = old_ref_mod;
 533         existing->ref_mod += update->ref_mod;
 534         existing->total_ref_mod += update->ref_mod;
 535
 536         /*
 537          * If we are going to from a positive ref mod to a negative or vice
 538          * versa we need to make sure to adjust pending_csums accordingly.
 539          */
 540         if (existing->is_data) {
 541                 u64 csum_leaves =
 542                         btrfs_csum_bytes_to_leaves(fs_info,
 543                                                    existing->num_bytes);
 544
 545                 if (existing->total_ref_mod >= 0 && old_ref_mod < 0) {
 546                         delayed_refs->pending_csums -= existing->num_bytes;
 547                         btrfs_delayed_refs_rsv_release(fs_info, csum_leaves);
 548                 }
 549                 if (existing->total_ref_mod < 0 && old_ref_mod >= 0) {
 550                         delayed_refs->pending_csums += existing->num_bytes;
 551                         trans->delayed_ref_updates += csum_leaves;
 552                 }
 553         }
 554         spin_unlock(&existing->lock);
 555 }
 556
 557 static void init_delayed_ref_head(struct btrfs_delayed_ref_head *head_ref,
 558                                   struct btrfs_qgroup_extent_record *qrecord,
 559                                   u64 bytenr, u64 num_bytes, u64 ref_root,
 560                                   u64 reserved, int action, bool is_data,
 561                                   bool is_system)
 562 {
 563         int count_mod = 1;
 564         int must_insert_reserved = 0;
 565
 566         /* If reserved is provided, it must be a data extent. */
 567         BUG_ON(!is_data && reserved);
 568
 569         /*
 570          * The head node stores the sum of all the mods, so dropping a ref
 571          * should drop the sum in the head node by one.
 572          */
 573         if (action == BTRFS_UPDATE_DELAYED_HEAD)
 574                 count_mod = 0;
 575         else if (action == BTRFS_DROP_DELAYED_REF)
 576                 count_mod = -1;
 577
 578         /*
 579          * BTRFS_ADD_DELAYED_EXTENT means that we need to update the reserved
 580          * accounting when the extent is finally added, or if a later
 581          * modification deletes the delayed ref without ever inserting the
 582          * extent into the extent allocation tree.  ref->must_insert_reserved
 583          * is the flag used to record that accounting mods are required.
 584          *
 585          * Once we record must_insert_reserved, switch the action to
 586          * BTRFS_ADD_DELAYED_REF because other special casing is not required.
 587          */
 588         if (action == BTRFS_ADD_DELAYED_EXTENT)
 589                 must_insert_reserved = 1;
 590         else
 591                 must_insert_reserved = 0;
 592
 593         refcount_set(&head_ref->refs, 1);
 594         head_ref->bytenr = bytenr;
 595         head_ref->num_bytes = num_bytes;
 596         head_ref->ref_mod = count_mod;
 597         head_ref->must_insert_reserved = must_insert_reserved;
 598         head_ref->is_data = is_data;
 599         head_ref->is_system = is_system;
 600         head_ref->ref_tree = RB_ROOT_CACHED;
 601         INIT_LIST_HEAD(&head_ref->ref_add_list);
 602         RB_CLEAR_NODE(&head_ref->href_node);
 603         head_ref->processing = 0;
 604         head_ref->total_ref_mod = count_mod;
 605         spin_lock_init(&head_ref->lock);
 606         mutex_init(&head_ref->mutex);
 607
 608         if (qrecord) {
 609                 if (ref_root && reserved) {
 610                         qrecord->data_rsv = reserved;
 611                         qrecord->data_rsv_refroot = ref_root;
 612                 }
 613                 qrecord->bytenr = bytenr;
 614                 qrecord->num_bytes = num_bytes;
 615                 qrecord->old_roots = NULL;
 616         }
 617 }
 618
 619 /*
 620  * helper function to actually insert a head node into the rbtree.
 621  * this does all the dirty work in terms of maintaining the correct
 622  * overall modification count.
 623  */
 624 static noinline struct btrfs_delayed_ref_head *
 625 add_delayed_ref_head(struct btrfs_trans_handle *trans,
 626                      struct btrfs_delayed_ref_head *head_ref,
 627                      struct btrfs_qgroup_extent_record *qrecord,
 628                      int action, int *qrecord_inserted_ret,
 629                      int *old_ref_mod, int *new_ref_mod)
 630 {
 631         struct btrfs_delayed_ref_head *existing;
 632         struct btrfs_delayed_ref_root *delayed_refs;
 633         int qrecord_inserted = 0;
 634
 635         delayed_refs = &trans->transaction->delayed_refs;
 636
 637         /* Record qgroup extent info if provided */
 638         if (qrecord) {
 639                 if (btrfs_qgroup_trace_extent_nolock(trans->fs_info,
 640                                         delayed_refs, qrecord))
 641                         kfree(qrecord);
 642                 else
 643                         qrecord_inserted = 1;
 644         }
 645
 646         trace_add_delayed_ref_head(trans->fs_info, head_ref, action);
 647
 648         existing = htree_insert(&delayed_refs->href_root,
 649                                 &head_ref->href_node);
 650         if (existing) {
 651                 update_existing_head_ref(trans, existing, head_ref,
 652                                          old_ref_mod);
 653                 /*
 654                  * we've updated the existing ref, free the newly
 655                  * allocated ref
 656                  */
 657                 kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 658                 head_ref = existing;
 659         } else {
 660                 if (old_ref_mod)
 661                         *old_ref_mod = 0;
 662                 if (head_ref->is_data && head_ref->ref_mod < 0) {
 663                         delayed_refs->pending_csums += head_ref->num_bytes;
 664                         trans->delayed_ref_updates +=
 665                                 btrfs_csum_bytes_to_leaves(trans->fs_info,
 666                                                            head_ref->num_bytes);
 667                 }
 668                 delayed_refs->num_heads++;
 669                 delayed_refs->num_heads_ready++;
 670                 atomic_inc(&delayed_refs->num_entries);
 671                 trans->delayed_ref_updates++;
 672         }
 673         if (qrecord_inserted_ret)
 674                 *qrecord_inserted_ret = qrecord_inserted;
 675         if (new_ref_mod)
 676                 *new_ref_mod = head_ref->total_ref_mod;
 677
 678         return head_ref;
 679 }
 680
 681 /*
 682  * init_delayed_ref_common - Initialize the structure which represents a
 683  *                           modification to a an extent.
 684  *
 685  * @fs_info:    Internal to the mounted filesystem mount structure.
 686  *
 687  * @ref:        The structure which is going to be initialized.
 688  *
 689  * @bytenr:     The logical address of the extent for which a modification is
 690  *              going to be recorded.
 691  *
 692  * @num_bytes:  Size of the extent whose modification is being recorded.
 693  *
 694  * @ref_root:   The id of the root where this modification has originated, this
 695  *              can be either one of the well-known metadata trees or the
 696  *              subvolume id which references this extent.
 697  *
 698  * @action:     Can be one of BTRFS_ADD_DELAYED_REF/BTRFS_DROP_DELAYED_REF or
 699  *              BTRFS_ADD_DELAYED_EXTENT
 700  *
 701  * @ref_type:   Holds the type of the extent which is being recorded, can be
 702  *              one of BTRFS_SHARED_BLOCK_REF_KEY/BTRFS_TREE_BLOCK_REF_KEY
 703  *              when recording a metadata extent or BTRFS_SHARED_DATA_REF_KEY/
 704  *              BTRFS_EXTENT_DATA_REF_KEY when recording data extent
 705  */
 706 static void init_delayed_ref_common(struct btrfs_fs_info *fs_info,
 707                                     struct btrfs_delayed_ref_node *ref,
 708                                     u64 bytenr, u64 num_bytes, u64 ref_root,
 709                                     int action, u8 ref_type)
 710 {
 711         u64 seq = 0;
 712
 713         if (action == BTRFS_ADD_DELAYED_EXTENT)
 714                 action = BTRFS_ADD_DELAYED_REF;
 715
 716         if (is_fstree(ref_root))
 717                 seq = atomic64_read(&fs_info->tree_mod_seq);
 718
 719         refcount_set(&ref->refs, 1);
 720         ref->bytenr = bytenr;
 721         ref->num_bytes = num_bytes;
 722         ref->ref_mod = 1;
 723         ref->action = action;
 724         ref->is_head = 0;
 725         ref->in_tree = 1;
 726         ref->seq = seq;
 727         ref->type = ref_type;
 728         RB_CLEAR_NODE(&ref->ref_node);
 729         INIT_LIST_HEAD(&ref->add_list);
 730 }
 731
 732 /*
 733  * add a delayed tree ref.  This does all of the accounting required
 734  * to make sure the delayed ref is eventually processed before this
 735  * transaction commits.
 736  */
 737 int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 738                                u64 bytenr, u64 num_bytes, u64 parent,
 739                                u64 ref_root,  int level, int action,
 740                                struct btrfs_delayed_extent_op *extent_op,
 741                                int *old_ref_mod, int *new_ref_mod)
 742 {
 743         struct btrfs_fs_info *fs_info = trans->fs_info;
 744         struct btrfs_delayed_tree_ref *ref;
 745         struct btrfs_delayed_ref_head *head_ref;
 746         struct btrfs_delayed_ref_root *delayed_refs;
 747         struct btrfs_qgroup_extent_record *record = NULL;
 748         int qrecord_inserted;
 749         bool is_system = (ref_root == BTRFS_CHUNK_TREE_OBJECTID);
 750         int ret;
 751         u8 ref_type;
 752
 753         BUG_ON(extent_op && extent_op->is_data);
 754         ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
 755         if (!ref)
 756                 return -ENOMEM;
 757
 758         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 759         if (!head_ref) {
 760                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 761                 return -ENOMEM;
 762         }
 763
 764         if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
 765             is_fstree(ref_root)) {
 766                 record = kzalloc(sizeof(*record), GFP_NOFS);
 767                 if (!record) {
 768                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 769                         kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 770                         return -ENOMEM;
 771                 }
 772         }
 773
 774         if (parent)
 775                 ref_type = BTRFS_SHARED_BLOCK_REF_KEY;
 776         else
 777                 ref_type = BTRFS_TREE_BLOCK_REF_KEY;
 778
 779         init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
 780                                 ref_root, action, ref_type);
 781         ref->root = ref_root;
 782         ref->parent = parent;
 783         ref->level = level;
 784
 785         init_delayed_ref_head(head_ref, record, bytenr, num_bytes,
 786                               ref_root, 0, action, false, is_system);
 787         head_ref->extent_op = extent_op;
 788
 789         delayed_refs = &trans->transaction->delayed_refs;
 790         spin_lock(&delayed_refs->lock);
 791
 792         /*
 793          * insert both the head node and the new ref without dropping
 794          * the spin lock
 795          */
 796         head_ref = add_delayed_ref_head(trans, head_ref, record,
 797                                         action, &qrecord_inserted,
 798                                         old_ref_mod, new_ref_mod);
 799
 800         ret = insert_delayed_ref(trans, delayed_refs, head_ref, &ref->node);
 801         spin_unlock(&delayed_refs->lock);
 802
 803         /*
 804          * Need to update the delayed_refs_rsv with any changes we may have
 805          * made.
 806          */
 807         btrfs_update_delayed_refs_rsv(trans);
 808
 809         trace_add_delayed_tree_ref(fs_info, &ref->node, ref,
 810                                    action == BTRFS_ADD_DELAYED_EXTENT ?
 811                                    BTRFS_ADD_DELAYED_REF : action);
 812         if (ret > 0)
 813                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 814
 815         if (qrecord_inserted)
 816                 btrfs_qgroup_trace_extent_post(fs_info, record);
 817
 818         return 0;
 819 }
 820
 821 /*
 822  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 823  */
 824 int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 825                                u64 bytenr, u64 num_bytes,
 826                                u64 parent, u64 ref_root,
 827                                u64 owner, u64 offset, u64 reserved, int action,
 828                                int *old_ref_mod, int *new_ref_mod)
 829 {
 830         struct btrfs_fs_info *fs_info = trans->fs_info;
 831         struct btrfs_delayed_data_ref *ref;
 832         struct btrfs_delayed_ref_head *head_ref;
 833         struct btrfs_delayed_ref_root *delayed_refs;
 834         struct btrfs_qgroup_extent_record *record = NULL;
 835         int qrecord_inserted;
 836         int ret;
 837         u8 ref_type;
 838
 839         ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
 840         if (!ref)
 841                 return -ENOMEM;
 842
 843         if (parent)
 844                 ref_type = BTRFS_SHARED_DATA_REF_KEY;
 845         else
 846                 ref_type = BTRFS_EXTENT_DATA_REF_KEY;
 847         init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
 848                                 ref_root, action, ref_type);
 849         ref->root = ref_root;
 850         ref->parent = parent;
 851         ref->objectid = owner;
 852         ref->offset = offset;
 853
 854
 855         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 856         if (!head_ref) {
 857                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 858                 return -ENOMEM;
 859         }
 860
 861         if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
 862             is_fstree(ref_root)) {
 863                 record = kzalloc(sizeof(*record), GFP_NOFS);
 864                 if (!record) {
 865                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 866                         kmem_cache_free(btrfs_delayed_ref_head_cachep,
 867                                         head_ref);
 868                         return -ENOMEM;
 869                 }
 870         }
 871
 872         init_delayed_ref_head(head_ref, record, bytenr, num_bytes, ref_root,
 873                               reserved, action, true, false);
 874         head_ref->extent_op = NULL;
 875
 876         delayed_refs = &trans->transaction->delayed_refs;
 877         spin_lock(&delayed_refs->lock);
 878
 879         /*
 880          * insert both the head node and the new ref without dropping
 881          * the spin lock
 882          */
 883         head_ref = add_delayed_ref_head(trans, head_ref, record,
 884                                         action, &qrecord_inserted,
 885                                         old_ref_mod, new_ref_mod);
 886
 887         ret = insert_delayed_ref(trans, delayed_refs, head_ref, &ref->node);
 888         spin_unlock(&delayed_refs->lock);
 889
 890         /*
 891          * Need to update the delayed_refs_rsv with any changes we may have
 892          * made.
 893          */
 894         btrfs_update_delayed_refs_rsv(trans);
 895
 896         trace_add_delayed_data_ref(trans->fs_info, &ref->node, ref,
 897                                    action == BTRFS_ADD_DELAYED_EXTENT ?
 898                                    BTRFS_ADD_DELAYED_REF : action);
 899         if (ret > 0)
 900                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 901
 902
 903         if (qrecord_inserted)
 904                 return btrfs_qgroup_trace_extent_post(fs_info, record);
 905         return 0;
 906 }
 907
 908 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 909                                 struct btrfs_trans_handle *trans,
 910                                 u64 bytenr, u64 num_bytes,
 911                                 struct btrfs_delayed_extent_op *extent_op)
 912 {
 913         struct btrfs_delayed_ref_head *head_ref;
 914         struct btrfs_delayed_ref_root *delayed_refs;
 915
 916         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 917         if (!head_ref)
 918                 return -ENOMEM;
 919
 920         init_delayed_ref_head(head_ref, NULL, bytenr, num_bytes, 0, 0,
 921                               BTRFS_UPDATE_DELAYED_HEAD, extent_op->is_data,
 922                               false);
 923         head_ref->extent_op = extent_op;
 924
 925         delayed_refs = &trans->transaction->delayed_refs;
 926         spin_lock(&delayed_refs->lock);
 927
 928         add_delayed_ref_head(trans, head_ref, NULL, BTRFS_UPDATE_DELAYED_HEAD,
 929                              NULL, NULL, NULL);
 930
 931         spin_unlock(&delayed_refs->lock);
 932
 933         /*
 934          * Need to update the delayed_refs_rsv with any changes we may have
 935          * made.
 936          */
 937         btrfs_update_delayed_refs_rsv(trans);
 938         return 0;
 939 }
 940
 941 /*
 942  * this does a simple search for the head node for a given extent.
 943  * It must be called with the delayed ref spinlock held, and it returns
 944  * the head node if any where found, or NULL if not.
 945  */
 946 struct btrfs_delayed_ref_head *
 947 btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 bytenr)
 948 {
 949         return find_ref_head(delayed_refs, bytenr, false);
 950 }
 951
 952 void __cold btrfs_delayed_ref_exit(void)
 953 {
 954         kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
 955         kmem_cache_destroy(btrfs_delayed_tree_ref_cachep);
 956         kmem_cache_destroy(btrfs_delayed_data_ref_cachep);
 957         kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
 958 }
 959
 960 int __init btrfs_delayed_ref_init(void)
 961 {
 962         btrfs_delayed_ref_head_cachep = kmem_cache_create(
 963                                 "btrfs_delayed_ref_head",
 964                                 sizeof(struct btrfs_delayed_ref_head), 0,
 965                                 SLAB_MEM_SPREAD, NULL);
 966         if (!btrfs_delayed_ref_head_cachep)
 967                 goto fail;
 968
 969         btrfs_delayed_tree_ref_cachep = kmem_cache_create(
 970                                 "btrfs_delayed_tree_ref",
 971                                 sizeof(struct btrfs_delayed_tree_ref), 0,
 972                                 SLAB_MEM_SPREAD, NULL);
 973         if (!btrfs_delayed_tree_ref_cachep)
 974                 goto fail;
 975
 976         btrfs_delayed_data_ref_cachep = kmem_cache_create(
 977                                 "btrfs_delayed_data_ref",
 978                                 sizeof(struct btrfs_delayed_data_ref), 0,
 979                                 SLAB_MEM_SPREAD, NULL);
 980         if (!btrfs_delayed_data_ref_cachep)
 981                 goto fail;
 982
 983         btrfs_delayed_extent_op_cachep = kmem_cache_create(
 984                                 "btrfs_delayed_extent_op",
 985                                 sizeof(struct btrfs_delayed_extent_op), 0,
 986                                 SLAB_MEM_SPREAD, NULL);
 987         if (!btrfs_delayed_extent_op_cachep)
 988                 goto fail;
 989
 990         return 0;
 991 fail:
 992         btrfs_delayed_ref_exit();
 993         return -ENOMEM;
 994 }