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 "messages.h"
  10 #include "ctree.h"
  11 #include "delayed-ref.h"
  12 #include "transaction.h"
  13 #include "qgroup.h"
  14 #include "space-info.h"
  15 #include "tree-mod-log.h"
  16 #include "fs.h"
  17
  18 struct kmem_cache *btrfs_delayed_ref_head_cachep;
  19 struct kmem_cache *btrfs_delayed_tree_ref_cachep;
  20 struct kmem_cache *btrfs_delayed_data_ref_cachep;
  21 struct kmem_cache *btrfs_delayed_extent_op_cachep;
  22 /*
  23  * delayed back reference update tracking.  For subvolume trees
  24  * we queue up extent allocations and backref maintenance for
  25  * delayed processing.   This avoids deep call chains where we
  26  * add extents in the middle of btrfs_search_slot, and it allows
  27  * us to buffer up frequently modified backrefs in an rb tree instead
  28  * of hammering updates on the extent allocation tree.
  29  */
  30
  31 bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info)
  32 {
  33         struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
  34         struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
  35         bool ret = false;
  36         u64 reserved;
  37
  38         spin_lock(&global_rsv->lock);
  39         reserved = global_rsv->reserved;
  40         spin_unlock(&global_rsv->lock);
  41
  42         /*
  43          * Since the global reserve is just kind of magic we don't really want
  44          * to rely on it to save our bacon, so if our size is more than the
  45          * delayed_refs_rsv and the global rsv then it's time to think about
  46          * bailing.
  47          */
  48         spin_lock(&delayed_refs_rsv->lock);
  49         reserved += delayed_refs_rsv->reserved;
  50         if (delayed_refs_rsv->size >= reserved)
  51                 ret = true;
  52         spin_unlock(&delayed_refs_rsv->lock);
  53         return ret;
  54 }
  55
  56 /*
  57  * Release a ref head's reservation.
  58  *
  59  * @fs_info:  the filesystem
  60  * @nr:       number of items to drop
  61  *
  62  * Drops the delayed ref head's count from the delayed refs rsv and free any
  63  * excess reservation we had.
  64  */
  65 void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr)
  66 {
  67         struct btrfs_block_rsv *block_rsv = &fs_info->delayed_refs_rsv;
  68         const u64 num_bytes = btrfs_calc_delayed_ref_bytes(fs_info, nr);
  69         u64 released = 0;
  70
  71         released = btrfs_block_rsv_release(fs_info, block_rsv, num_bytes, NULL);
  72         if (released)
  73                 trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv",
  74                                               0, released, 0);
  75 }
  76
  77 /*
  78  * Adjust the size of the delayed refs rsv.
  79  *
  80  * This is to be called anytime we may have adjusted trans->delayed_ref_updates,
  81  * it'll calculate the additional size and add it to the delayed_refs_rsv.
  82  */
  83 void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans)
  84 {
  85         struct btrfs_fs_info *fs_info = trans->fs_info;
  86         struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
  87         u64 num_bytes;
  88
  89         if (!trans->delayed_ref_updates)
  90                 return;
  91
  92         num_bytes = btrfs_calc_delayed_ref_bytes(fs_info,
  93                                                  trans->delayed_ref_updates);
  94
  95         spin_lock(&delayed_rsv->lock);
  96         delayed_rsv->size += num_bytes;
  97         delayed_rsv->full = false;
  98         spin_unlock(&delayed_rsv->lock);
  99         trans->delayed_ref_updates = 0;
 100 }
 101
 102 /*
 103  * Transfer bytes to our delayed refs rsv.
 104  *
 105  * @fs_info:   the filesystem
 106  * @num_bytes: number of bytes to transfer
 107  *
 108  * This transfers up to the num_bytes amount, previously reserved, to the
 109  * delayed_refs_rsv.  Any extra bytes are returned to the space info.
 110  */
 111 void btrfs_migrate_to_delayed_refs_rsv(struct btrfs_fs_info *fs_info,
 112                                        u64 num_bytes)
 113 {
 114         struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
 115         u64 to_free = 0;
 116
 117         spin_lock(&delayed_refs_rsv->lock);
 118         if (delayed_refs_rsv->size > delayed_refs_rsv->reserved) {
 119                 u64 delta = delayed_refs_rsv->size -
 120                         delayed_refs_rsv->reserved;
 121                 if (num_bytes > delta) {
 122                         to_free = num_bytes - delta;
 123                         num_bytes = delta;
 124                 }
 125         } else {
 126                 to_free = num_bytes;
 127                 num_bytes = 0;
 128         }
 129
 130         if (num_bytes)
 131                 delayed_refs_rsv->reserved += num_bytes;
 132         if (delayed_refs_rsv->reserved >= delayed_refs_rsv->size)
 133                 delayed_refs_rsv->full = true;
 134         spin_unlock(&delayed_refs_rsv->lock);
 135
 136         if (num_bytes)
 137                 trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv",
 138                                               0, num_bytes, 1);
 139         if (to_free)
 140                 btrfs_space_info_free_bytes_may_use(fs_info,
 141                                 delayed_refs_rsv->space_info, to_free);
 142 }
 143
 144 /*
 145  * Refill based on our delayed refs usage.
 146  *
 147  * @fs_info: the filesystem
 148  * @flush:   control how we can flush for this reservation.
 149  *
 150  * This will refill the delayed block_rsv up to 1 items size worth of space and
 151  * will return -ENOSPC if we can't make the reservation.
 152  */
 153 int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
 154                                   enum btrfs_reserve_flush_enum flush)
 155 {
 156         struct btrfs_block_rsv *block_rsv = &fs_info->delayed_refs_rsv;
 157         u64 limit = btrfs_calc_delayed_ref_bytes(fs_info, 1);
 158         u64 num_bytes = 0;
 159         u64 refilled_bytes;
 160         u64 to_free;
 161         int ret = -ENOSPC;
 162
 163         spin_lock(&block_rsv->lock);
 164         if (block_rsv->reserved < block_rsv->size) {
 165                 num_bytes = block_rsv->size - block_rsv->reserved;
 166                 num_bytes = min(num_bytes, limit);
 167         }
 168         spin_unlock(&block_rsv->lock);
 169
 170         if (!num_bytes)
 171                 return 0;
 172
 173         ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv, num_bytes, flush);
 174         if (ret)
 175                 return ret;
 176
 177         /*
 178          * We may have raced with someone else, so check again if we the block
 179          * reserve is still not full and release any excess space.
 180          */
 181         spin_lock(&block_rsv->lock);
 182         if (block_rsv->reserved < block_rsv->size) {
 183                 u64 needed = block_rsv->size - block_rsv->reserved;
 184
 185                 if (num_bytes >= needed) {
 186                         block_rsv->reserved += needed;
 187                         block_rsv->full = true;
 188                         to_free = num_bytes - needed;
 189                         refilled_bytes = needed;
 190                 } else {
 191                         block_rsv->reserved += num_bytes;
 192                         to_free = 0;
 193                         refilled_bytes = num_bytes;
 194                 }
 195         } else {
 196                 to_free = num_bytes;
 197                 refilled_bytes = 0;
 198         }
 199         spin_unlock(&block_rsv->lock);
 200
 201         if (to_free > 0)
 202                 btrfs_space_info_free_bytes_may_use(fs_info, block_rsv->space_info,
 203                                                     to_free);
 204
 205         if (refilled_bytes > 0)
 206                 trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv", 0,
 207                                               refilled_bytes, 1);
 208         return 0;
 209 }
 210
 211 /*
 212  * compare two delayed tree backrefs with same bytenr and type
 213  */
 214 static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref1,
 215                           struct btrfs_delayed_tree_ref *ref2)
 216 {
 217         if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) {
 218                 if (ref1->root < ref2->root)
 219                         return -1;
 220                 if (ref1->root > ref2->root)
 221                         return 1;
 222         } else {
 223                 if (ref1->parent < ref2->parent)
 224                         return -1;
 225                 if (ref1->parent > ref2->parent)
 226                         return 1;
 227         }
 228         return 0;
 229 }
 230
 231 /*
 232  * compare two delayed data backrefs with same bytenr and type
 233  */
 234 static int comp_data_refs(struct btrfs_delayed_data_ref *ref1,
 235                           struct btrfs_delayed_data_ref *ref2)
 236 {
 237         if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
 238                 if (ref1->root < ref2->root)
 239                         return -1;
 240                 if (ref1->root > ref2->root)
 241                         return 1;
 242                 if (ref1->objectid < ref2->objectid)
 243                         return -1;
 244                 if (ref1->objectid > ref2->objectid)
 245                         return 1;
 246                 if (ref1->offset < ref2->offset)
 247                         return -1;
 248                 if (ref1->offset > ref2->offset)
 249                         return 1;
 250         } else {
 251                 if (ref1->parent < ref2->parent)
 252                         return -1;
 253                 if (ref1->parent > ref2->parent)
 254                         return 1;
 255         }
 256         return 0;
 257 }
 258
 259 static int comp_refs(struct btrfs_delayed_ref_node *ref1,
 260                      struct btrfs_delayed_ref_node *ref2,
 261                      bool check_seq)
 262 {
 263         int ret = 0;
 264
 265         if (ref1->type < ref2->type)
 266                 return -1;
 267         if (ref1->type > ref2->type)
 268                 return 1;
 269         if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
 270             ref1->type == BTRFS_SHARED_BLOCK_REF_KEY)
 271                 ret = comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref1),
 272                                      btrfs_delayed_node_to_tree_ref(ref2));
 273         else
 274                 ret = comp_data_refs(btrfs_delayed_node_to_data_ref(ref1),
 275                                      btrfs_delayed_node_to_data_ref(ref2));
 276         if (ret)
 277                 return ret;
 278         if (check_seq) {
 279                 if (ref1->seq < ref2->seq)
 280                         return -1;
 281                 if (ref1->seq > ref2->seq)
 282                         return 1;
 283         }
 284         return 0;
 285 }
 286
 287 /* insert a new ref to head ref rbtree */
 288 static struct btrfs_delayed_ref_head *htree_insert(struct rb_root_cached *root,
 289                                                    struct rb_node *node)
 290 {
 291         struct rb_node **p = &root->rb_root.rb_node;
 292         struct rb_node *parent_node = NULL;
 293         struct btrfs_delayed_ref_head *entry;
 294         struct btrfs_delayed_ref_head *ins;
 295         u64 bytenr;
 296         bool leftmost = true;
 297
 298         ins = rb_entry(node, struct btrfs_delayed_ref_head, href_node);
 299         bytenr = ins->bytenr;
 300         while (*p) {
 301                 parent_node = *p;
 302                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_head,
 303                                  href_node);
 304
 305                 if (bytenr < entry->bytenr) {
 306                         p = &(*p)->rb_left;
 307                 } else if (bytenr > entry->bytenr) {
 308                         p = &(*p)->rb_right;
 309                         leftmost = false;
 310                 } else {
 311                         return entry;
 312                 }
 313         }
 314
 315         rb_link_node(node, parent_node, p);
 316         rb_insert_color_cached(node, root, leftmost);
 317         return NULL;
 318 }
 319
 320 static struct btrfs_delayed_ref_node* tree_insert(struct rb_root_cached *root,
 321                 struct btrfs_delayed_ref_node *ins)
 322 {
 323         struct rb_node **p = &root->rb_root.rb_node;
 324         struct rb_node *node = &ins->ref_node;
 325         struct rb_node *parent_node = NULL;
 326         struct btrfs_delayed_ref_node *entry;
 327         bool leftmost = true;
 328
 329         while (*p) {
 330                 int comp;
 331
 332                 parent_node = *p;
 333                 entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
 334                                  ref_node);
 335                 comp = comp_refs(ins, entry, true);
 336                 if (comp < 0) {
 337                         p = &(*p)->rb_left;
 338                 } else if (comp > 0) {
 339                         p = &(*p)->rb_right;
 340                         leftmost = false;
 341                 } else {
 342                         return entry;
 343                 }
 344         }
 345
 346         rb_link_node(node, parent_node, p);
 347         rb_insert_color_cached(node, root, leftmost);
 348         return NULL;
 349 }
 350
 351 static struct btrfs_delayed_ref_head *find_first_ref_head(
 352                 struct btrfs_delayed_ref_root *dr)
 353 {
 354         struct rb_node *n;
 355         struct btrfs_delayed_ref_head *entry;
 356
 357         n = rb_first_cached(&dr->href_root);
 358         if (!n)
 359                 return NULL;
 360
 361         entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
 362
 363         return entry;
 364 }
 365
 366 /*
 367  * Find a head entry based on bytenr. This returns the delayed ref head if it
 368  * was able to find one, or NULL if nothing was in that spot.  If return_bigger
 369  * is given, the next bigger entry is returned if no exact match is found.
 370  */
 371 static struct btrfs_delayed_ref_head *find_ref_head(
 372                 struct btrfs_delayed_ref_root *dr, u64 bytenr,
 373                 bool return_bigger)
 374 {
 375         struct rb_root *root = &dr->href_root.rb_root;
 376         struct rb_node *n;
 377         struct btrfs_delayed_ref_head *entry;
 378
 379         n = root->rb_node;
 380         entry = NULL;
 381         while (n) {
 382                 entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
 383
 384                 if (bytenr < entry->bytenr)
 385                         n = n->rb_left;
 386                 else if (bytenr > entry->bytenr)
 387                         n = n->rb_right;
 388                 else
 389                         return entry;
 390         }
 391         if (entry && return_bigger) {
 392                 if (bytenr > entry->bytenr) {
 393                         n = rb_next(&entry->href_node);
 394                         if (!n)
 395                                 return NULL;
 396                         entry = rb_entry(n, struct btrfs_delayed_ref_head,
 397                                          href_node);
 398                 }
 399                 return entry;
 400         }
 401         return NULL;
 402 }
 403
 404 int btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,
 405                            struct btrfs_delayed_ref_head *head)
 406 {
 407         lockdep_assert_held(&delayed_refs->lock);
 408         if (mutex_trylock(&head->mutex))
 409                 return 0;
 410
 411         refcount_inc(&head->refs);
 412         spin_unlock(&delayed_refs->lock);
 413
 414         mutex_lock(&head->mutex);
 415         spin_lock(&delayed_refs->lock);
 416         if (RB_EMPTY_NODE(&head->href_node)) {
 417                 mutex_unlock(&head->mutex);
 418                 btrfs_put_delayed_ref_head(head);
 419                 return -EAGAIN;
 420         }
 421         btrfs_put_delayed_ref_head(head);
 422         return 0;
 423 }
 424
 425 static inline void drop_delayed_ref(struct btrfs_delayed_ref_root *delayed_refs,
 426                                     struct btrfs_delayed_ref_head *head,
 427                                     struct btrfs_delayed_ref_node *ref)
 428 {
 429         lockdep_assert_held(&head->lock);
 430         rb_erase_cached(&ref->ref_node, &head->ref_tree);
 431         RB_CLEAR_NODE(&ref->ref_node);
 432         if (!list_empty(&ref->add_list))
 433                 list_del(&ref->add_list);
 434         btrfs_put_delayed_ref(ref);
 435         atomic_dec(&delayed_refs->num_entries);
 436 }
 437
 438 static bool merge_ref(struct btrfs_delayed_ref_root *delayed_refs,
 439                       struct btrfs_delayed_ref_head *head,
 440                       struct btrfs_delayed_ref_node *ref,
 441                       u64 seq)
 442 {
 443         struct btrfs_delayed_ref_node *next;
 444         struct rb_node *node = rb_next(&ref->ref_node);
 445         bool done = false;
 446
 447         while (!done && node) {
 448                 int mod;
 449
 450                 next = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
 451                 node = rb_next(node);
 452                 if (seq && next->seq >= seq)
 453                         break;
 454                 if (comp_refs(ref, next, false))
 455                         break;
 456
 457                 if (ref->action == next->action) {
 458                         mod = next->ref_mod;
 459                 } else {
 460                         if (ref->ref_mod < next->ref_mod) {
 461                                 swap(ref, next);
 462                                 done = true;
 463                         }
 464                         mod = -next->ref_mod;
 465                 }
 466
 467                 drop_delayed_ref(delayed_refs, head, next);
 468                 ref->ref_mod += mod;
 469                 if (ref->ref_mod == 0) {
 470                         drop_delayed_ref(delayed_refs, head, ref);
 471                         done = true;
 472                 } else {
 473                         /*
 474                          * Can't have multiples of the same ref on a tree block.
 475                          */
 476                         WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
 477                                 ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
 478                 }
 479         }
 480
 481         return done;
 482 }
 483
 484 void btrfs_merge_delayed_refs(struct btrfs_fs_info *fs_info,
 485                               struct btrfs_delayed_ref_root *delayed_refs,
 486                               struct btrfs_delayed_ref_head *head)
 487 {
 488         struct btrfs_delayed_ref_node *ref;
 489         struct rb_node *node;
 490         u64 seq = 0;
 491
 492         lockdep_assert_held(&head->lock);
 493
 494         if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
 495                 return;
 496
 497         /* We don't have too many refs to merge for data. */
 498         if (head->is_data)
 499                 return;
 500
 501         seq = btrfs_tree_mod_log_lowest_seq(fs_info);
 502 again:
 503         for (node = rb_first_cached(&head->ref_tree); node;
 504              node = rb_next(node)) {
 505                 ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
 506                 if (seq && ref->seq >= seq)
 507                         continue;
 508                 if (merge_ref(delayed_refs, head, ref, seq))
 509                         goto again;
 510         }
 511 }
 512
 513 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq)
 514 {
 515         int ret = 0;
 516         u64 min_seq = btrfs_tree_mod_log_lowest_seq(fs_info);
 517
 518         if (min_seq != 0 && seq >= min_seq) {
 519                 btrfs_debug(fs_info,
 520                             "holding back delayed_ref %llu, lowest is %llu",
 521                             seq, min_seq);
 522                 ret = 1;
 523         }
 524
 525         return ret;
 526 }
 527
 528 struct btrfs_delayed_ref_head *btrfs_select_ref_head(
 529                 struct btrfs_delayed_ref_root *delayed_refs)
 530 {
 531         struct btrfs_delayed_ref_head *head;
 532
 533         lockdep_assert_held(&delayed_refs->lock);
 534 again:
 535         head = find_ref_head(delayed_refs, delayed_refs->run_delayed_start,
 536                              true);
 537         if (!head && delayed_refs->run_delayed_start != 0) {
 538                 delayed_refs->run_delayed_start = 0;
 539                 head = find_first_ref_head(delayed_refs);
 540         }
 541         if (!head)
 542                 return NULL;
 543
 544         while (head->processing) {
 545                 struct rb_node *node;
 546
 547                 node = rb_next(&head->href_node);
 548                 if (!node) {
 549                         if (delayed_refs->run_delayed_start == 0)
 550                                 return NULL;
 551                         delayed_refs->run_delayed_start = 0;
 552                         goto again;
 553                 }
 554                 head = rb_entry(node, struct btrfs_delayed_ref_head,
 555                                 href_node);
 556         }
 557
 558         head->processing = true;
 559         WARN_ON(delayed_refs->num_heads_ready == 0);
 560         delayed_refs->num_heads_ready--;
 561         delayed_refs->run_delayed_start = head->bytenr +
 562                 head->num_bytes;
 563         return head;
 564 }
 565
 566 void btrfs_delete_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 567                            struct btrfs_delayed_ref_head *head)
 568 {
 569         lockdep_assert_held(&delayed_refs->lock);
 570         lockdep_assert_held(&head->lock);
 571
 572         rb_erase_cached(&head->href_node, &delayed_refs->href_root);
 573         RB_CLEAR_NODE(&head->href_node);
 574         atomic_dec(&delayed_refs->num_entries);
 575         delayed_refs->num_heads--;
 576         if (!head->processing)
 577                 delayed_refs->num_heads_ready--;
 578 }
 579
 580 /*
 581  * Helper to insert the ref_node to the tail or merge with tail.
 582  *
 583  * Return false if the ref was inserted.
 584  * Return true if the ref was merged into an existing one (and therefore can be
 585  * freed by the caller).
 586  */
 587 static bool insert_delayed_ref(struct btrfs_delayed_ref_root *root,
 588                                struct btrfs_delayed_ref_head *href,
 589                                struct btrfs_delayed_ref_node *ref)
 590 {
 591         struct btrfs_delayed_ref_node *exist;
 592         int mod;
 593
 594         spin_lock(&href->lock);
 595         exist = tree_insert(&href->ref_tree, ref);
 596         if (!exist) {
 597                 if (ref->action == BTRFS_ADD_DELAYED_REF)
 598                         list_add_tail(&ref->add_list, &href->ref_add_list);
 599                 atomic_inc(&root->num_entries);
 600                 spin_unlock(&href->lock);
 601                 return false;
 602         }
 603
 604         /* Now we are sure we can merge */
 605         if (exist->action == ref->action) {
 606                 mod = ref->ref_mod;
 607         } else {
 608                 /* Need to change action */
 609                 if (exist->ref_mod < ref->ref_mod) {
 610                         exist->action = ref->action;
 611                         mod = -exist->ref_mod;
 612                         exist->ref_mod = ref->ref_mod;
 613                         if (ref->action == BTRFS_ADD_DELAYED_REF)
 614                                 list_add_tail(&exist->add_list,
 615                                               &href->ref_add_list);
 616                         else if (ref->action == BTRFS_DROP_DELAYED_REF) {
 617                                 ASSERT(!list_empty(&exist->add_list));
 618                                 list_del(&exist->add_list);
 619                         } else {
 620                                 ASSERT(0);
 621                         }
 622                 } else
 623                         mod = -ref->ref_mod;
 624         }
 625         exist->ref_mod += mod;
 626
 627         /* remove existing tail if its ref_mod is zero */
 628         if (exist->ref_mod == 0)
 629                 drop_delayed_ref(root, href, exist);
 630         spin_unlock(&href->lock);
 631         return true;
 632 }
 633
 634 /*
 635  * helper function to update the accounting in the head ref
 636  * existing and update must have the same bytenr
 637  */
 638 static noinline void update_existing_head_ref(struct btrfs_trans_handle *trans,
 639                          struct btrfs_delayed_ref_head *existing,
 640                          struct btrfs_delayed_ref_head *update)
 641 {
 642         struct btrfs_delayed_ref_root *delayed_refs =
 643                 &trans->transaction->delayed_refs;
 644         struct btrfs_fs_info *fs_info = trans->fs_info;
 645         int old_ref_mod;
 646
 647         BUG_ON(existing->is_data != update->is_data);
 648
 649         spin_lock(&existing->lock);
 650         if (update->must_insert_reserved) {
 651                 /* if the extent was freed and then
 652                  * reallocated before the delayed ref
 653                  * entries were processed, we can end up
 654                  * with an existing head ref without
 655                  * the must_insert_reserved flag set.
 656                  * Set it again here
 657                  */
 658                 existing->must_insert_reserved = update->must_insert_reserved;
 659
 660                 /*
 661                  * update the num_bytes so we make sure the accounting
 662                  * is done correctly
 663                  */
 664                 existing->num_bytes = update->num_bytes;
 665
 666         }
 667
 668         if (update->extent_op) {
 669                 if (!existing->extent_op) {
 670                         existing->extent_op = update->extent_op;
 671                 } else {
 672                         if (update->extent_op->update_key) {
 673                                 memcpy(&existing->extent_op->key,
 674                                        &update->extent_op->key,
 675                                        sizeof(update->extent_op->key));
 676                                 existing->extent_op->update_key = true;
 677                         }
 678                         if (update->extent_op->update_flags) {
 679                                 existing->extent_op->flags_to_set |=
 680                                         update->extent_op->flags_to_set;
 681                                 existing->extent_op->update_flags = true;
 682                         }
 683                         btrfs_free_delayed_extent_op(update->extent_op);
 684                 }
 685         }
 686         /*
 687          * update the reference mod on the head to reflect this new operation,
 688          * only need the lock for this case cause we could be processing it
 689          * currently, for refs we just added we know we're a-ok.
 690          */
 691         old_ref_mod = existing->total_ref_mod;
 692         existing->ref_mod += update->ref_mod;
 693         existing->total_ref_mod += update->ref_mod;
 694
 695         /*
 696          * If we are going to from a positive ref mod to a negative or vice
 697          * versa we need to make sure to adjust pending_csums accordingly.
 698          */
 699         if (existing->is_data) {
 700                 u64 csum_leaves =
 701                         btrfs_csum_bytes_to_leaves(fs_info,
 702                                                    existing->num_bytes);
 703
 704                 if (existing->total_ref_mod >= 0 && old_ref_mod < 0) {
 705                         delayed_refs->pending_csums -= existing->num_bytes;
 706                         btrfs_delayed_refs_rsv_release(fs_info, csum_leaves);
 707                 }
 708                 if (existing->total_ref_mod < 0 && old_ref_mod >= 0) {
 709                         delayed_refs->pending_csums += existing->num_bytes;
 710                         trans->delayed_ref_updates += csum_leaves;
 711                 }
 712         }
 713
 714         spin_unlock(&existing->lock);
 715 }
 716
 717 static void init_delayed_ref_head(struct btrfs_delayed_ref_head *head_ref,
 718                                   struct btrfs_qgroup_extent_record *qrecord,
 719                                   u64 bytenr, u64 num_bytes, u64 ref_root,
 720                                   u64 reserved, int action, bool is_data,
 721                                   bool is_system)
 722 {
 723         int count_mod = 1;
 724         bool must_insert_reserved = false;
 725
 726         /* If reserved is provided, it must be a data extent. */
 727         BUG_ON(!is_data && reserved);
 728
 729         switch (action) {
 730         case BTRFS_UPDATE_DELAYED_HEAD:
 731                 count_mod = 0;
 732                 break;
 733         case BTRFS_DROP_DELAYED_REF:
 734                 /*
 735                  * The head node stores the sum of all the mods, so dropping a ref
 736                  * should drop the sum in the head node by one.
 737                  */
 738                 count_mod = -1;
 739                 break;
 740         case BTRFS_ADD_DELAYED_EXTENT:
 741                 /*
 742                  * BTRFS_ADD_DELAYED_EXTENT means that we need to update the
 743                  * reserved accounting when the extent is finally added, or if a
 744                  * later modification deletes the delayed ref without ever
 745                  * inserting the extent into the extent allocation tree.
 746                  * ref->must_insert_reserved is the flag used to record that
 747                  * accounting mods are required.
 748                  *
 749                  * Once we record must_insert_reserved, switch the action to
 750                  * BTRFS_ADD_DELAYED_REF because other special casing is not
 751                  * required.
 752                  */
 753                 must_insert_reserved = true;
 754                 break;
 755         }
 756
 757         refcount_set(&head_ref->refs, 1);
 758         head_ref->bytenr = bytenr;
 759         head_ref->num_bytes = num_bytes;
 760         head_ref->ref_mod = count_mod;
 761         head_ref->must_insert_reserved = must_insert_reserved;
 762         head_ref->is_data = is_data;
 763         head_ref->is_system = is_system;
 764         head_ref->ref_tree = RB_ROOT_CACHED;
 765         INIT_LIST_HEAD(&head_ref->ref_add_list);
 766         RB_CLEAR_NODE(&head_ref->href_node);
 767         head_ref->processing = false;
 768         head_ref->total_ref_mod = count_mod;
 769         spin_lock_init(&head_ref->lock);
 770         mutex_init(&head_ref->mutex);
 771
 772         if (qrecord) {
 773                 if (ref_root && reserved) {
 774                         qrecord->data_rsv = reserved;
 775                         qrecord->data_rsv_refroot = ref_root;
 776                 }
 777                 qrecord->bytenr = bytenr;
 778                 qrecord->num_bytes = num_bytes;
 779                 qrecord->old_roots = NULL;
 780         }
 781 }
 782
 783 /*
 784  * helper function to actually insert a head node into the rbtree.
 785  * this does all the dirty work in terms of maintaining the correct
 786  * overall modification count.
 787  */
 788 static noinline struct btrfs_delayed_ref_head *
 789 add_delayed_ref_head(struct btrfs_trans_handle *trans,
 790                      struct btrfs_delayed_ref_head *head_ref,
 791                      struct btrfs_qgroup_extent_record *qrecord,
 792                      int action, bool *qrecord_inserted_ret)
 793 {
 794         struct btrfs_delayed_ref_head *existing;
 795         struct btrfs_delayed_ref_root *delayed_refs;
 796         bool qrecord_inserted = false;
 797
 798         delayed_refs = &trans->transaction->delayed_refs;
 799
 800         /* Record qgroup extent info if provided */
 801         if (qrecord) {
 802                 if (btrfs_qgroup_trace_extent_nolock(trans->fs_info,
 803                                         delayed_refs, qrecord))
 804                         kfree(qrecord);
 805                 else
 806                         qrecord_inserted = true;
 807         }
 808
 809         trace_add_delayed_ref_head(trans->fs_info, head_ref, action);
 810
 811         existing = htree_insert(&delayed_refs->href_root,
 812                                 &head_ref->href_node);
 813         if (existing) {
 814                 update_existing_head_ref(trans, existing, head_ref);
 815                 /*
 816                  * we've updated the existing ref, free the newly
 817                  * allocated ref
 818                  */
 819                 kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 820                 head_ref = existing;
 821         } else {
 822                 if (head_ref->is_data && head_ref->ref_mod < 0) {
 823                         delayed_refs->pending_csums += head_ref->num_bytes;
 824                         trans->delayed_ref_updates +=
 825                                 btrfs_csum_bytes_to_leaves(trans->fs_info,
 826                                                            head_ref->num_bytes);
 827                 }
 828                 delayed_refs->num_heads++;
 829                 delayed_refs->num_heads_ready++;
 830                 atomic_inc(&delayed_refs->num_entries);
 831                 trans->delayed_ref_updates++;
 832         }
 833         if (qrecord_inserted_ret)
 834                 *qrecord_inserted_ret = qrecord_inserted;
 835
 836         return head_ref;
 837 }
 838
 839 /*
 840  * init_delayed_ref_common - Initialize the structure which represents a
 841  *                           modification to a an extent.
 842  *
 843  * @fs_info:    Internal to the mounted filesystem mount structure.
 844  *
 845  * @ref:        The structure which is going to be initialized.
 846  *
 847  * @bytenr:     The logical address of the extent for which a modification is
 848  *              going to be recorded.
 849  *
 850  * @num_bytes:  Size of the extent whose modification is being recorded.
 851  *
 852  * @ref_root:   The id of the root where this modification has originated, this
 853  *              can be either one of the well-known metadata trees or the
 854  *              subvolume id which references this extent.
 855  *
 856  * @action:     Can be one of BTRFS_ADD_DELAYED_REF/BTRFS_DROP_DELAYED_REF or
 857  *              BTRFS_ADD_DELAYED_EXTENT
 858  *
 859  * @ref_type:   Holds the type of the extent which is being recorded, can be
 860  *              one of BTRFS_SHARED_BLOCK_REF_KEY/BTRFS_TREE_BLOCK_REF_KEY
 861  *              when recording a metadata extent or BTRFS_SHARED_DATA_REF_KEY/
 862  *              BTRFS_EXTENT_DATA_REF_KEY when recording data extent
 863  */
 864 static void init_delayed_ref_common(struct btrfs_fs_info *fs_info,
 865                                     struct btrfs_delayed_ref_node *ref,
 866                                     u64 bytenr, u64 num_bytes, u64 ref_root,
 867                                     int action, u8 ref_type)
 868 {
 869         u64 seq = 0;
 870
 871         if (action == BTRFS_ADD_DELAYED_EXTENT)
 872                 action = BTRFS_ADD_DELAYED_REF;
 873
 874         if (is_fstree(ref_root))
 875                 seq = atomic64_read(&fs_info->tree_mod_seq);
 876
 877         refcount_set(&ref->refs, 1);
 878         ref->bytenr = bytenr;
 879         ref->num_bytes = num_bytes;
 880         ref->ref_mod = 1;
 881         ref->action = action;
 882         ref->seq = seq;
 883         ref->type = ref_type;
 884         RB_CLEAR_NODE(&ref->ref_node);
 885         INIT_LIST_HEAD(&ref->add_list);
 886 }
 887
 888 /*
 889  * add a delayed tree ref.  This does all of the accounting required
 890  * to make sure the delayed ref is eventually processed before this
 891  * transaction commits.
 892  */
 893 int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 894                                struct btrfs_ref *generic_ref,
 895                                struct btrfs_delayed_extent_op *extent_op)
 896 {
 897         struct btrfs_fs_info *fs_info = trans->fs_info;
 898         struct btrfs_delayed_tree_ref *ref;
 899         struct btrfs_delayed_ref_head *head_ref;
 900         struct btrfs_delayed_ref_root *delayed_refs;
 901         struct btrfs_qgroup_extent_record *record = NULL;
 902         bool qrecord_inserted;
 903         bool is_system;
 904         bool merged;
 905         int action = generic_ref->action;
 906         int level = generic_ref->tree_ref.level;
 907         u64 bytenr = generic_ref->bytenr;
 908         u64 num_bytes = generic_ref->len;
 909         u64 parent = generic_ref->parent;
 910         u8 ref_type;
 911
 912         is_system = (generic_ref->tree_ref.owning_root == BTRFS_CHUNK_TREE_OBJECTID);
 913
 914         ASSERT(generic_ref->type == BTRFS_REF_METADATA && generic_ref->action);
 915         ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
 916         if (!ref)
 917                 return -ENOMEM;
 918
 919         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 920         if (!head_ref) {
 921                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 922                 return -ENOMEM;
 923         }
 924
 925         if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
 926             !generic_ref->skip_qgroup) {
 927                 record = kzalloc(sizeof(*record), GFP_NOFS);
 928                 if (!record) {
 929                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 930                         kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 931                         return -ENOMEM;
 932                 }
 933         }
 934
 935         if (parent)
 936                 ref_type = BTRFS_SHARED_BLOCK_REF_KEY;
 937         else
 938                 ref_type = BTRFS_TREE_BLOCK_REF_KEY;
 939
 940         init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
 941                                 generic_ref->tree_ref.owning_root, action,
 942                                 ref_type);
 943         ref->root = generic_ref->tree_ref.owning_root;
 944         ref->parent = parent;
 945         ref->level = level;
 946
 947         init_delayed_ref_head(head_ref, record, bytenr, num_bytes,
 948                               generic_ref->tree_ref.owning_root, 0, action,
 949                               false, is_system);
 950         head_ref->extent_op = extent_op;
 951
 952         delayed_refs = &trans->transaction->delayed_refs;
 953         spin_lock(&delayed_refs->lock);
 954
 955         /*
 956          * insert both the head node and the new ref without dropping
 957          * the spin lock
 958          */
 959         head_ref = add_delayed_ref_head(trans, head_ref, record,
 960                                         action, &qrecord_inserted);
 961
 962         merged = insert_delayed_ref(delayed_refs, head_ref, &ref->node);
 963         spin_unlock(&delayed_refs->lock);
 964
 965         /*
 966          * Need to update the delayed_refs_rsv with any changes we may have
 967          * made.
 968          */
 969         btrfs_update_delayed_refs_rsv(trans);
 970
 971         trace_add_delayed_tree_ref(fs_info, &ref->node, ref,
 972                                    action == BTRFS_ADD_DELAYED_EXTENT ?
 973                                    BTRFS_ADD_DELAYED_REF : action);
 974         if (merged)
 975                 kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 976
 977         if (qrecord_inserted)
 978                 btrfs_qgroup_trace_extent_post(trans, record);
 979
 980         return 0;
 981 }
 982
 983 /*
 984  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
 985  */
 986 int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 987                                struct btrfs_ref *generic_ref,
 988                                u64 reserved)
 989 {
 990         struct btrfs_fs_info *fs_info = trans->fs_info;
 991         struct btrfs_delayed_data_ref *ref;
 992         struct btrfs_delayed_ref_head *head_ref;
 993         struct btrfs_delayed_ref_root *delayed_refs;
 994         struct btrfs_qgroup_extent_record *record = NULL;
 995         bool qrecord_inserted;
 996         int action = generic_ref->action;
 997         bool merged;
 998         u64 bytenr = generic_ref->bytenr;
 999         u64 num_bytes = generic_ref->len;
1000         u64 parent = generic_ref->parent;
1001         u64 ref_root = generic_ref->data_ref.owning_root;
1002         u64 owner = generic_ref->data_ref.ino;
1003         u64 offset = generic_ref->data_ref.offset;
1004         u8 ref_type;
1005
1006         ASSERT(generic_ref->type == BTRFS_REF_DATA && action);
1007         ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
1008         if (!ref)
1009                 return -ENOMEM;
1010
1011         if (parent)
1012                 ref_type = BTRFS_SHARED_DATA_REF_KEY;
1013         else
1014                 ref_type = BTRFS_EXTENT_DATA_REF_KEY;
1015         init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
1016                                 ref_root, action, ref_type);
1017         ref->root = ref_root;
1018         ref->parent = parent;
1019         ref->objectid = owner;
1020         ref->offset = offset;
1021
1022
1023         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
1024         if (!head_ref) {
1025                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
1026                 return -ENOMEM;
1027         }
1028
1029         if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
1030             !generic_ref->skip_qgroup) {
1031                 record = kzalloc(sizeof(*record), GFP_NOFS);
1032                 if (!record) {
1033                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
1034                         kmem_cache_free(btrfs_delayed_ref_head_cachep,
1035                                         head_ref);
1036                         return -ENOMEM;
1037                 }
1038         }
1039
1040         init_delayed_ref_head(head_ref, record, bytenr, num_bytes, ref_root,
1041                               reserved, action, true, false);
1042         head_ref->extent_op = NULL;
1043
1044         delayed_refs = &trans->transaction->delayed_refs;
1045         spin_lock(&delayed_refs->lock);
1046
1047         /*
1048          * insert both the head node and the new ref without dropping
1049          * the spin lock
1050          */
1051         head_ref = add_delayed_ref_head(trans, head_ref, record,
1052                                         action, &qrecord_inserted);
1053
1054         merged = insert_delayed_ref(delayed_refs, head_ref, &ref->node);
1055         spin_unlock(&delayed_refs->lock);
1056
1057         /*
1058          * Need to update the delayed_refs_rsv with any changes we may have
1059          * made.
1060          */
1061         btrfs_update_delayed_refs_rsv(trans);
1062
1063         trace_add_delayed_data_ref(trans->fs_info, &ref->node, ref,
1064                                    action == BTRFS_ADD_DELAYED_EXTENT ?
1065                                    BTRFS_ADD_DELAYED_REF : action);
1066         if (merged)
1067                 kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
1068
1069
1070         if (qrecord_inserted)
1071                 return btrfs_qgroup_trace_extent_post(trans, record);
1072         return 0;
1073 }
1074
1075 int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
1076                                 u64 bytenr, u64 num_bytes,
1077                                 struct btrfs_delayed_extent_op *extent_op)
1078 {
1079         struct btrfs_delayed_ref_head *head_ref;
1080         struct btrfs_delayed_ref_root *delayed_refs;
1081
1082         head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
1083         if (!head_ref)
1084                 return -ENOMEM;
1085
1086         init_delayed_ref_head(head_ref, NULL, bytenr, num_bytes, 0, 0,
1087                               BTRFS_UPDATE_DELAYED_HEAD, false, false);
1088         head_ref->extent_op = extent_op;
1089
1090         delayed_refs = &trans->transaction->delayed_refs;
1091         spin_lock(&delayed_refs->lock);
1092
1093         add_delayed_ref_head(trans, head_ref, NULL, BTRFS_UPDATE_DELAYED_HEAD,
1094                              NULL);
1095
1096         spin_unlock(&delayed_refs->lock);
1097
1098         /*
1099          * Need to update the delayed_refs_rsv with any changes we may have
1100          * made.
1101          */
1102         btrfs_update_delayed_refs_rsv(trans);
1103         return 0;
1104 }
1105
1106 /*
1107  * This does a simple search for the head node for a given extent.  Returns the
1108  * head node if found, or NULL if not.
1109  */
1110 struct btrfs_delayed_ref_head *
1111 btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 bytenr)
1112 {
1113         lockdep_assert_held(&delayed_refs->lock);
1114
1115         return find_ref_head(delayed_refs, bytenr, false);
1116 }
1117
1118 void __cold btrfs_delayed_ref_exit(void)
1119 {
1120         kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
1121         kmem_cache_destroy(btrfs_delayed_tree_ref_cachep);
1122         kmem_cache_destroy(btrfs_delayed_data_ref_cachep);
1123         kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
1124 }
1125
1126 int __init btrfs_delayed_ref_init(void)
1127 {
1128         btrfs_delayed_ref_head_cachep = kmem_cache_create(
1129                                 "btrfs_delayed_ref_head",
1130                                 sizeof(struct btrfs_delayed_ref_head), 0,
1131                                 SLAB_MEM_SPREAD, NULL);
1132         if (!btrfs_delayed_ref_head_cachep)
1133                 goto fail;
1134
1135         btrfs_delayed_tree_ref_cachep = kmem_cache_create(
1136                                 "btrfs_delayed_tree_ref",
1137                                 sizeof(struct btrfs_delayed_tree_ref), 0,
1138                                 SLAB_MEM_SPREAD, NULL);
1139         if (!btrfs_delayed_tree_ref_cachep)
1140                 goto fail;
1141
1142         btrfs_delayed_data_ref_cachep = kmem_cache_create(
1143                                 "btrfs_delayed_data_ref",
1144                                 sizeof(struct btrfs_delayed_data_ref), 0,
1145                                 SLAB_MEM_SPREAD, NULL);
1146         if (!btrfs_delayed_data_ref_cachep)
1147                 goto fail;
1148
1149         btrfs_delayed_extent_op_cachep = kmem_cache_create(
1150                                 "btrfs_delayed_extent_op",
1151                                 sizeof(struct btrfs_delayed_extent_op), 0,
1152                                 SLAB_MEM_SPREAD, NULL);
1153         if (!btrfs_delayed_extent_op_cachep)
1154                 goto fail;
1155
1156         return 0;
1157 fail:
1158         btrfs_delayed_ref_exit();
1159         return -ENOMEM;
1160 }