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 "extent-tree.h"
  13#include "transaction.h"
  14#include "qgroup.h"
  15#include "space-info.h"
  16#include "tree-mod-log.h"
  17#include "fs.h"
  18
  19struct kmem_cache *btrfs_delayed_ref_head_cachep;
  20struct kmem_cache *btrfs_delayed_ref_node_cachep;
 
  21struct 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
  31bool 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_refs:  number of delayed refs to drop
  61 * @nr_csums: number of csum items to drop
  62 *
  63 * Drops the delayed ref head's count from the delayed refs rsv and free any
  64 * excess reservation we had.
  65 */
  66void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr_refs, int nr_csums)
  67{
  68	struct btrfs_block_rsv *block_rsv = &fs_info->delayed_refs_rsv;
  69	u64 num_bytes;
  70	u64 released;
  71
  72	num_bytes = btrfs_calc_delayed_ref_bytes(fs_info, nr_refs);
  73	num_bytes += btrfs_calc_delayed_ref_csum_bytes(fs_info, nr_csums);
  74
  75	released = btrfs_block_rsv_release(fs_info, block_rsv, num_bytes, NULL);
  76	if (released)
  77		trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv",
  78					      0, released, 0);
  79}
  80
  81/*
  82 * Adjust the size of the delayed refs rsv.
  83 *
  84 * This is to be called anytime we may have adjusted trans->delayed_ref_updates
  85 * or trans->delayed_ref_csum_deletions, it'll calculate the additional size and
  86 * add it to the delayed_refs_rsv.
  87 */
  88void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans)
  89{
  90	struct btrfs_fs_info *fs_info = trans->fs_info;
  91	struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
  92	struct btrfs_block_rsv *local_rsv = &trans->delayed_rsv;
  93	u64 num_bytes;
  94	u64 reserved_bytes;
  95
  96	num_bytes = btrfs_calc_delayed_ref_bytes(fs_info, trans->delayed_ref_updates);
  97	num_bytes += btrfs_calc_delayed_ref_csum_bytes(fs_info,
  98						       trans->delayed_ref_csum_deletions);
  99
 100	if (num_bytes == 0)
 101		return;
 102
 103	/*
 104	 * Try to take num_bytes from the transaction's local delayed reserve.
 105	 * If not possible, try to take as much as it's available. If the local
 106	 * reserve doesn't have enough reserved space, the delayed refs reserve
 107	 * will be refilled next time btrfs_delayed_refs_rsv_refill() is called
 108	 * by someone or if a transaction commit is triggered before that, the
 109	 * global block reserve will be used. We want to minimize using the
 110	 * global block reserve for cases we can account for in advance, to
 111	 * avoid exhausting it and reach -ENOSPC during a transaction commit.
 112	 */
 113	spin_lock(&local_rsv->lock);
 114	reserved_bytes = min(num_bytes, local_rsv->reserved);
 115	local_rsv->reserved -= reserved_bytes;
 116	local_rsv->full = (local_rsv->reserved >= local_rsv->size);
 117	spin_unlock(&local_rsv->lock);
 118
 119	spin_lock(&delayed_rsv->lock);
 120	delayed_rsv->size += num_bytes;
 121	delayed_rsv->reserved += reserved_bytes;
 122	delayed_rsv->full = (delayed_rsv->reserved >= delayed_rsv->size);
 123	spin_unlock(&delayed_rsv->lock);
 124	trans->delayed_ref_updates = 0;
 125	trans->delayed_ref_csum_deletions = 0;
 126}
 127
 128/*
 129 * Adjust the size of the delayed refs block reserve for 1 block group item
 130 * insertion, used after allocating a block group.
 131 */
 132void btrfs_inc_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info)
 133{
 134	struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
 135
 136	spin_lock(&delayed_rsv->lock);
 137	/*
 138	 * Inserting a block group item does not require changing the free space
 139	 * tree, only the extent tree or the block group tree, so this is all we
 140	 * need.
 141	 */
 142	delayed_rsv->size += btrfs_calc_insert_metadata_size(fs_info, 1);
 143	delayed_rsv->full = false;
 144	spin_unlock(&delayed_rsv->lock);
 145}
 146
 147/*
 148 * Adjust the size of the delayed refs block reserve to release space for 1
 149 * block group item insertion.
 150 */
 151void btrfs_dec_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info)
 152{
 153	struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
 154	const u64 num_bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
 155	u64 released;
 156
 157	released = btrfs_block_rsv_release(fs_info, delayed_rsv, num_bytes, NULL);
 158	if (released > 0)
 159		trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv",
 160					      0, released, 0);
 161}
 162
 163/*
 164 * Adjust the size of the delayed refs block reserve for 1 block group item
 165 * update.
 166 */
 167void btrfs_inc_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info)
 168{
 169	struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
 170
 171	spin_lock(&delayed_rsv->lock);
 172	/*
 173	 * Updating a block group item does not result in new nodes/leaves and
 174	 * does not require changing the free space tree, only the extent tree
 175	 * or the block group tree, so this is all we need.
 176	 */
 177	delayed_rsv->size += btrfs_calc_metadata_size(fs_info, 1);
 178	delayed_rsv->full = false;
 179	spin_unlock(&delayed_rsv->lock);
 180}
 181
 182/*
 183 * Adjust the size of the delayed refs block reserve to release space for 1
 184 * block group item update.
 185 */
 186void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info)
 187{
 188	struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
 189	const u64 num_bytes = btrfs_calc_metadata_size(fs_info, 1);
 190	u64 released;
 191
 192	released = btrfs_block_rsv_release(fs_info, delayed_rsv, num_bytes, NULL);
 193	if (released > 0)
 194		trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv",
 195					      0, released, 0);
 196}
 197
 198/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 199 * Refill based on our delayed refs usage.
 200 *
 201 * @fs_info: the filesystem
 202 * @flush:   control how we can flush for this reservation.
 203 *
 204 * This will refill the delayed block_rsv up to 1 items size worth of space and
 205 * will return -ENOSPC if we can't make the reservation.
 206 */
 207int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
 208				  enum btrfs_reserve_flush_enum flush)
 209{
 210	struct btrfs_block_rsv *block_rsv = &fs_info->delayed_refs_rsv;
 211	struct btrfs_space_info *space_info = block_rsv->space_info;
 212	u64 limit = btrfs_calc_delayed_ref_bytes(fs_info, 1);
 213	u64 num_bytes = 0;
 214	u64 refilled_bytes;
 215	u64 to_free;
 216	int ret = -ENOSPC;
 217
 218	spin_lock(&block_rsv->lock);
 219	if (block_rsv->reserved < block_rsv->size) {
 220		num_bytes = block_rsv->size - block_rsv->reserved;
 221		num_bytes = min(num_bytes, limit);
 222	}
 223	spin_unlock(&block_rsv->lock);
 224
 225	if (!num_bytes)
 226		return 0;
 227
 228	ret = btrfs_reserve_metadata_bytes(fs_info, space_info, num_bytes, flush);
 229	if (ret)
 230		return ret;
 231
 232	/*
 233	 * We may have raced with someone else, so check again if we the block
 234	 * reserve is still not full and release any excess space.
 235	 */
 236	spin_lock(&block_rsv->lock);
 237	if (block_rsv->reserved < block_rsv->size) {
 238		u64 needed = block_rsv->size - block_rsv->reserved;
 239
 240		if (num_bytes >= needed) {
 241			block_rsv->reserved += needed;
 242			block_rsv->full = true;
 243			to_free = num_bytes - needed;
 244			refilled_bytes = needed;
 245		} else {
 246			block_rsv->reserved += num_bytes;
 247			to_free = 0;
 248			refilled_bytes = num_bytes;
 249		}
 250	} else {
 251		to_free = num_bytes;
 252		refilled_bytes = 0;
 253	}
 254	spin_unlock(&block_rsv->lock);
 255
 256	if (to_free > 0)
 257		btrfs_space_info_free_bytes_may_use(fs_info, space_info, to_free);
 258
 259	if (refilled_bytes > 0)
 260		trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv", 0,
 261					      refilled_bytes, 1);
 262	return 0;
 263}
 264
 265/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 266 * compare two delayed data backrefs with same bytenr and type
 267 */
 268static int comp_data_refs(struct btrfs_delayed_ref_node *ref1,
 269			  struct btrfs_delayed_ref_node *ref2)
 270{
 271	if (ref1->data_ref.objectid < ref2->data_ref.objectid)
 272		return -1;
 273	if (ref1->data_ref.objectid > ref2->data_ref.objectid)
 274		return 1;
 275	if (ref1->data_ref.offset < ref2->data_ref.offset)
 276		return -1;
 277	if (ref1->data_ref.offset > ref2->data_ref.offset)
 278		return 1;
 
 
 
 
 
 
 
 
 
 
 
 279	return 0;
 280}
 281
 282static int comp_refs(struct btrfs_delayed_ref_node *ref1,
 283		     struct btrfs_delayed_ref_node *ref2,
 284		     bool check_seq)
 285{
 286	int ret = 0;
 287
 288	if (ref1->type < ref2->type)
 289		return -1;
 290	if (ref1->type > ref2->type)
 291		return 1;
 292	if (ref1->type == BTRFS_SHARED_BLOCK_REF_KEY ||
 293	    ref1->type == BTRFS_SHARED_DATA_REF_KEY) {
 294		if (ref1->parent < ref2->parent)
 295			return -1;
 296		if (ref1->parent > ref2->parent)
 297			return 1;
 298	} else {
 299		if (ref1->ref_root < ref2->ref_root)
 300			return -1;
 301		if (ref1->ref_root > ref2->ref_root)
 302			return 1;
 303		if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY)
 304			ret = comp_data_refs(ref1, ref2);
 305	}
 306	if (ret)
 307		return ret;
 308	if (check_seq) {
 309		if (ref1->seq < ref2->seq)
 310			return -1;
 311		if (ref1->seq > ref2->seq)
 312			return 1;
 313	}
 314	return 0;
 315}
 316
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 317static struct btrfs_delayed_ref_node* tree_insert(struct rb_root_cached *root,
 318		struct btrfs_delayed_ref_node *ins)
 319{
 320	struct rb_node **p = &root->rb_root.rb_node;
 321	struct rb_node *node = &ins->ref_node;
 322	struct rb_node *parent_node = NULL;
 323	struct btrfs_delayed_ref_node *entry;
 324	bool leftmost = true;
 325
 326	while (*p) {
 327		int comp;
 328
 329		parent_node = *p;
 330		entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
 331				 ref_node);
 332		comp = comp_refs(ins, entry, true);
 333		if (comp < 0) {
 334			p = &(*p)->rb_left;
 335		} else if (comp > 0) {
 336			p = &(*p)->rb_right;
 337			leftmost = false;
 338		} else {
 339			return entry;
 340		}
 341	}
 342
 343	rb_link_node(node, parent_node, p);
 344	rb_insert_color_cached(node, root, leftmost);
 345	return NULL;
 346}
 347
 348static struct btrfs_delayed_ref_head *find_first_ref_head(
 349		struct btrfs_delayed_ref_root *dr)
 350{
 351	unsigned long from = 0;
 
 
 
 
 
 352
 353	lockdep_assert_held(&dr->lock);
 354
 355	return xa_find(&dr->head_refs, &from, ULONG_MAX, XA_PRESENT);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 356}
 357
 358static bool btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,
 359				   struct btrfs_delayed_ref_head *head)
 360{
 361	lockdep_assert_held(&delayed_refs->lock);
 362	if (mutex_trylock(&head->mutex))
 363		return true;
 364
 365	refcount_inc(&head->refs);
 366	spin_unlock(&delayed_refs->lock);
 367
 368	mutex_lock(&head->mutex);
 369	spin_lock(&delayed_refs->lock);
 370	if (!head->tracked) {
 371		mutex_unlock(&head->mutex);
 372		btrfs_put_delayed_ref_head(head);
 373		return false;
 374	}
 375	btrfs_put_delayed_ref_head(head);
 376	return true;
 377}
 378
 379static inline void drop_delayed_ref(struct btrfs_fs_info *fs_info,
 380				    struct btrfs_delayed_ref_root *delayed_refs,
 381				    struct btrfs_delayed_ref_head *head,
 382				    struct btrfs_delayed_ref_node *ref)
 383{
 384	lockdep_assert_held(&head->lock);
 385	rb_erase_cached(&ref->ref_node, &head->ref_tree);
 386	RB_CLEAR_NODE(&ref->ref_node);
 387	if (!list_empty(&ref->add_list))
 388		list_del(&ref->add_list);
 389	btrfs_put_delayed_ref(ref);
 
 390	btrfs_delayed_refs_rsv_release(fs_info, 1, 0);
 391}
 392
 393static bool merge_ref(struct btrfs_fs_info *fs_info,
 394		      struct btrfs_delayed_ref_root *delayed_refs,
 395		      struct btrfs_delayed_ref_head *head,
 396		      struct btrfs_delayed_ref_node *ref,
 397		      u64 seq)
 398{
 399	struct btrfs_delayed_ref_node *next;
 400	struct rb_node *node = rb_next(&ref->ref_node);
 401	bool done = false;
 402
 403	while (!done && node) {
 404		int mod;
 405
 406		next = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
 407		node = rb_next(node);
 408		if (seq && next->seq >= seq)
 409			break;
 410		if (comp_refs(ref, next, false))
 411			break;
 412
 413		if (ref->action == next->action) {
 414			mod = next->ref_mod;
 415		} else {
 416			if (ref->ref_mod < next->ref_mod) {
 417				swap(ref, next);
 418				done = true;
 419			}
 420			mod = -next->ref_mod;
 421		}
 422
 423		drop_delayed_ref(fs_info, delayed_refs, head, next);
 424		ref->ref_mod += mod;
 425		if (ref->ref_mod == 0) {
 426			drop_delayed_ref(fs_info, delayed_refs, head, ref);
 427			done = true;
 428		} else {
 429			/*
 430			 * Can't have multiples of the same ref on a tree block.
 431			 */
 432			WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
 433				ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
 434		}
 435	}
 436
 437	return done;
 438}
 439
 440void btrfs_merge_delayed_refs(struct btrfs_fs_info *fs_info,
 441			      struct btrfs_delayed_ref_root *delayed_refs,
 442			      struct btrfs_delayed_ref_head *head)
 443{
 444	struct btrfs_delayed_ref_node *ref;
 445	struct rb_node *node;
 446	u64 seq = 0;
 447
 448	lockdep_assert_held(&head->lock);
 449
 450	if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
 451		return;
 452
 453	/* We don't have too many refs to merge for data. */
 454	if (head->is_data)
 455		return;
 456
 457	seq = btrfs_tree_mod_log_lowest_seq(fs_info);
 458again:
 459	for (node = rb_first_cached(&head->ref_tree); node;
 460	     node = rb_next(node)) {
 461		ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
 462		if (seq && ref->seq >= seq)
 463			continue;
 464		if (merge_ref(fs_info, delayed_refs, head, ref, seq))
 465			goto again;
 466	}
 467}
 468
 469int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq)
 470{
 471	int ret = 0;
 472	u64 min_seq = btrfs_tree_mod_log_lowest_seq(fs_info);
 473
 474	if (min_seq != 0 && seq >= min_seq) {
 475		btrfs_debug(fs_info,
 476			    "holding back delayed_ref %llu, lowest is %llu",
 477			    seq, min_seq);
 478		ret = 1;
 479	}
 480
 481	return ret;
 482}
 483
 484struct btrfs_delayed_ref_head *btrfs_select_ref_head(
 485		const struct btrfs_fs_info *fs_info,
 486		struct btrfs_delayed_ref_root *delayed_refs)
 487{
 488	struct btrfs_delayed_ref_head *head;
 489	unsigned long start_index;
 490	unsigned long found_index;
 491	bool found_head = false;
 492	bool locked;
 493
 494	spin_lock(&delayed_refs->lock);
 495again:
 496	start_index = (delayed_refs->run_delayed_start >> fs_info->sectorsize_bits);
 497	xa_for_each_start(&delayed_refs->head_refs, found_index, head, start_index) {
 498		if (!head->processing) {
 499			found_head = true;
 500			break;
 501		}
 502	}
 503	if (!found_head) {
 504		if (delayed_refs->run_delayed_start == 0) {
 505			spin_unlock(&delayed_refs->lock);
 506			return NULL;
 
 
 
 
 
 
 
 
 507		}
 508		delayed_refs->run_delayed_start = 0;
 509		goto again;
 510	}
 511
 512	head->processing = true;
 513	WARN_ON(delayed_refs->num_heads_ready == 0);
 514	delayed_refs->num_heads_ready--;
 515	delayed_refs->run_delayed_start = head->bytenr +
 516		head->num_bytes;
 517
 518	locked = btrfs_delayed_ref_lock(delayed_refs, head);
 519	spin_unlock(&delayed_refs->lock);
 520
 521	/*
 522	 * We may have dropped the spin lock to get the head mutex lock, and
 523	 * that might have given someone else time to free the head.  If that's
 524	 * true, it has been removed from our list and we can move on.
 525	 */
 526	if (!locked)
 527		return ERR_PTR(-EAGAIN);
 528
 529	return head;
 530}
 531
 532void btrfs_unselect_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 533			     struct btrfs_delayed_ref_head *head)
 534{
 535	spin_lock(&delayed_refs->lock);
 536	head->processing = false;
 537	delayed_refs->num_heads_ready++;
 538	spin_unlock(&delayed_refs->lock);
 539	btrfs_delayed_ref_unlock(head);
 540}
 541
 542void btrfs_delete_ref_head(const struct btrfs_fs_info *fs_info,
 543			   struct btrfs_delayed_ref_root *delayed_refs,
 544			   struct btrfs_delayed_ref_head *head)
 545{
 546	const unsigned long index = (head->bytenr >> fs_info->sectorsize_bits);
 547
 548	lockdep_assert_held(&delayed_refs->lock);
 549	lockdep_assert_held(&head->lock);
 550
 551	xa_erase(&delayed_refs->head_refs, index);
 552	head->tracked = false;
 
 553	delayed_refs->num_heads--;
 554	if (!head->processing)
 555		delayed_refs->num_heads_ready--;
 556}
 557
 558/*
 559 * Helper to insert the ref_node to the tail or merge with tail.
 560 *
 561 * Return false if the ref was inserted.
 562 * Return true if the ref was merged into an existing one (and therefore can be
 563 * freed by the caller).
 564 */
 565static bool insert_delayed_ref(struct btrfs_trans_handle *trans,
 566			       struct btrfs_delayed_ref_head *href,
 567			       struct btrfs_delayed_ref_node *ref)
 568{
 569	struct btrfs_delayed_ref_root *root = &trans->transaction->delayed_refs;
 570	struct btrfs_delayed_ref_node *exist;
 571	int mod;
 572
 573	spin_lock(&href->lock);
 574	exist = tree_insert(&href->ref_tree, ref);
 575	if (!exist) {
 576		if (ref->action == BTRFS_ADD_DELAYED_REF)
 577			list_add_tail(&ref->add_list, &href->ref_add_list);
 
 578		spin_unlock(&href->lock);
 579		trans->delayed_ref_updates++;
 580		return false;
 581	}
 582
 583	/* Now we are sure we can merge */
 584	if (exist->action == ref->action) {
 585		mod = ref->ref_mod;
 586	} else {
 587		/* Need to change action */
 588		if (exist->ref_mod < ref->ref_mod) {
 589			exist->action = ref->action;
 590			mod = -exist->ref_mod;
 591			exist->ref_mod = ref->ref_mod;
 592			if (ref->action == BTRFS_ADD_DELAYED_REF)
 593				list_add_tail(&exist->add_list,
 594					      &href->ref_add_list);
 595			else if (ref->action == BTRFS_DROP_DELAYED_REF) {
 596				ASSERT(!list_empty(&exist->add_list));
 597				list_del_init(&exist->add_list);
 598			} else {
 599				ASSERT(0);
 600			}
 601		} else
 602			mod = -ref->ref_mod;
 603	}
 604	exist->ref_mod += mod;
 605
 606	/* remove existing tail if its ref_mod is zero */
 607	if (exist->ref_mod == 0)
 608		drop_delayed_ref(trans->fs_info, root, href, exist);
 609	spin_unlock(&href->lock);
 610	return true;
 611}
 612
 613/*
 614 * helper function to update the accounting in the head ref
 615 * existing and update must have the same bytenr
 616 */
 617static noinline void update_existing_head_ref(struct btrfs_trans_handle *trans,
 618			 struct btrfs_delayed_ref_head *existing,
 619			 struct btrfs_delayed_ref_head *update)
 620{
 621	struct btrfs_delayed_ref_root *delayed_refs =
 622		&trans->transaction->delayed_refs;
 623	struct btrfs_fs_info *fs_info = trans->fs_info;
 624	int old_ref_mod;
 625
 626	BUG_ON(existing->is_data != update->is_data);
 627
 628	spin_lock(&existing->lock);
 629
 630	/*
 631	 * When freeing an extent, we may not know the owning root when we
 632	 * first create the head_ref. However, some deref before the last deref
 633	 * will know it, so we just need to update the head_ref accordingly.
 634	 */
 635	if (!existing->owning_root)
 636		existing->owning_root = update->owning_root;
 637
 638	if (update->must_insert_reserved) {
 639		/* if the extent was freed and then
 640		 * reallocated before the delayed ref
 641		 * entries were processed, we can end up
 642		 * with an existing head ref without
 643		 * the must_insert_reserved flag set.
 644		 * Set it again here
 645		 */
 646		existing->must_insert_reserved = update->must_insert_reserved;
 647		existing->owning_root = update->owning_root;
 648
 649		/*
 650		 * update the num_bytes so we make sure the accounting
 651		 * is done correctly
 652		 */
 653		existing->num_bytes = update->num_bytes;
 654
 655	}
 656
 657	if (update->extent_op) {
 658		if (!existing->extent_op) {
 659			existing->extent_op = update->extent_op;
 660		} else {
 661			if (update->extent_op->update_key) {
 662				memcpy(&existing->extent_op->key,
 663				       &update->extent_op->key,
 664				       sizeof(update->extent_op->key));
 665				existing->extent_op->update_key = true;
 666			}
 667			if (update->extent_op->update_flags) {
 668				existing->extent_op->flags_to_set |=
 669					update->extent_op->flags_to_set;
 670				existing->extent_op->update_flags = true;
 671			}
 672			btrfs_free_delayed_extent_op(update->extent_op);
 673		}
 674	}
 675	/*
 676	 * update the reference mod on the head to reflect this new operation,
 677	 * only need the lock for this case cause we could be processing it
 678	 * currently, for refs we just added we know we're a-ok.
 679	 */
 680	old_ref_mod = existing->total_ref_mod;
 681	existing->ref_mod += update->ref_mod;
 682	existing->total_ref_mod += update->ref_mod;
 683
 684	/*
 685	 * If we are going to from a positive ref mod to a negative or vice
 686	 * versa we need to make sure to adjust pending_csums accordingly.
 687	 * We reserve bytes for csum deletion when adding or updating a ref head
 688	 * see add_delayed_ref_head() for more details.
 689	 */
 690	if (existing->is_data) {
 691		u64 csum_leaves =
 692			btrfs_csum_bytes_to_leaves(fs_info,
 693						   existing->num_bytes);
 694
 695		if (existing->total_ref_mod >= 0 && old_ref_mod < 0) {
 696			delayed_refs->pending_csums -= existing->num_bytes;
 697			btrfs_delayed_refs_rsv_release(fs_info, 0, csum_leaves);
 698		}
 699		if (existing->total_ref_mod < 0 && old_ref_mod >= 0) {
 700			delayed_refs->pending_csums += existing->num_bytes;
 701			trans->delayed_ref_csum_deletions += csum_leaves;
 702		}
 703	}
 704
 705	spin_unlock(&existing->lock);
 706}
 707
 708static void init_delayed_ref_head(struct btrfs_delayed_ref_head *head_ref,
 709				  struct btrfs_ref *generic_ref,
 710				  struct btrfs_qgroup_extent_record *qrecord,
 711				  u64 reserved)
 
 
 712{
 713	int count_mod = 1;
 714	bool must_insert_reserved = false;
 715
 716	/* If reserved is provided, it must be a data extent. */
 717	BUG_ON(generic_ref->type != BTRFS_REF_DATA && reserved);
 718
 719	switch (generic_ref->action) {
 720	case BTRFS_ADD_DELAYED_REF:
 721		/* count_mod is already set to 1. */
 722		break;
 723	case BTRFS_UPDATE_DELAYED_HEAD:
 724		count_mod = 0;
 725		break;
 726	case BTRFS_DROP_DELAYED_REF:
 727		/*
 728		 * The head node stores the sum of all the mods, so dropping a ref
 729		 * should drop the sum in the head node by one.
 730		 */
 731		count_mod = -1;
 732		break;
 733	case BTRFS_ADD_DELAYED_EXTENT:
 734		/*
 735		 * BTRFS_ADD_DELAYED_EXTENT means that we need to update the
 736		 * reserved accounting when the extent is finally added, or if a
 737		 * later modification deletes the delayed ref without ever
 738		 * inserting the extent into the extent allocation tree.
 739		 * ref->must_insert_reserved is the flag used to record that
 740		 * accounting mods are required.
 741		 *
 742		 * Once we record must_insert_reserved, switch the action to
 743		 * BTRFS_ADD_DELAYED_REF because other special casing is not
 744		 * required.
 745		 */
 746		must_insert_reserved = true;
 747		break;
 748	}
 749
 750	refcount_set(&head_ref->refs, 1);
 751	head_ref->bytenr = generic_ref->bytenr;
 752	head_ref->num_bytes = generic_ref->num_bytes;
 753	head_ref->ref_mod = count_mod;
 754	head_ref->reserved_bytes = reserved;
 755	head_ref->must_insert_reserved = must_insert_reserved;
 756	head_ref->owning_root = generic_ref->owning_root;
 757	head_ref->is_data = (generic_ref->type == BTRFS_REF_DATA);
 758	head_ref->is_system = (generic_ref->ref_root == BTRFS_CHUNK_TREE_OBJECTID);
 759	head_ref->ref_tree = RB_ROOT_CACHED;
 760	INIT_LIST_HEAD(&head_ref->ref_add_list);
 761	head_ref->tracked = false;
 762	head_ref->processing = false;
 763	head_ref->total_ref_mod = count_mod;
 764	spin_lock_init(&head_ref->lock);
 765	mutex_init(&head_ref->mutex);
 766
 767	/* If not metadata set an impossible level to help debugging. */
 768	if (generic_ref->type == BTRFS_REF_METADATA)
 769		head_ref->level = generic_ref->tree_ref.level;
 770	else
 771		head_ref->level = U8_MAX;
 772
 773	if (qrecord) {
 774		if (generic_ref->ref_root && reserved) {
 775			qrecord->data_rsv = reserved;
 776			qrecord->data_rsv_refroot = generic_ref->ref_root;
 777		}
 778		qrecord->num_bytes = generic_ref->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 * Returns an error pointer in case of an error.
 789 */
 790static noinline struct btrfs_delayed_ref_head *
 791add_delayed_ref_head(struct btrfs_trans_handle *trans,
 792		     struct btrfs_delayed_ref_head *head_ref,
 793		     struct btrfs_qgroup_extent_record *qrecord,
 794		     int action, bool *qrecord_inserted_ret)
 795{
 796	struct btrfs_fs_info *fs_info = trans->fs_info;
 797	struct btrfs_delayed_ref_head *existing;
 798	struct btrfs_delayed_ref_root *delayed_refs;
 799	const unsigned long index = (head_ref->bytenr >> fs_info->sectorsize_bits);
 800	bool qrecord_inserted = false;
 801
 802	delayed_refs = &trans->transaction->delayed_refs;
 803	lockdep_assert_held(&delayed_refs->lock);
 804
 805#if BITS_PER_LONG == 32
 806	if (head_ref->bytenr >= MAX_LFS_FILESIZE) {
 807		if (qrecord)
 808			xa_release(&delayed_refs->dirty_extents, index);
 809		btrfs_err_rl(fs_info,
 810"delayed ref head %llu is beyond 32bit page cache and xarray index limit",
 811			     head_ref->bytenr);
 812		btrfs_err_32bit_limit(fs_info);
 813		return ERR_PTR(-EOVERFLOW);
 814	}
 815#endif
 816
 817	/* Record qgroup extent info if provided */
 818	if (qrecord) {
 819		int ret;
 820
 821		ret = btrfs_qgroup_trace_extent_nolock(fs_info, delayed_refs, qrecord,
 822						       head_ref->bytenr);
 823		if (ret) {
 824			/* Clean up if insertion fails or item exists. */
 825			xa_release(&delayed_refs->dirty_extents, index);
 826			/* Caller responsible for freeing qrecord on error. */
 827			if (ret < 0)
 828				return ERR_PTR(ret);
 829			kfree(qrecord);
 830		} else {
 831			qrecord_inserted = true;
 832		}
 833	}
 834
 835	trace_add_delayed_ref_head(fs_info, head_ref, action);
 836
 837	existing = xa_load(&delayed_refs->head_refs, index);
 
 838	if (existing) {
 839		update_existing_head_ref(trans, existing, head_ref);
 840		/*
 841		 * we've updated the existing ref, free the newly
 842		 * allocated ref
 843		 */
 844		kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
 845		head_ref = existing;
 846	} else {
 847		existing = xa_store(&delayed_refs->head_refs, index, head_ref, GFP_ATOMIC);
 848		if (xa_is_err(existing)) {
 849			/* Memory was preallocated by the caller. */
 850			ASSERT(xa_err(existing) != -ENOMEM);
 851			return ERR_PTR(xa_err(existing));
 852		} else if (WARN_ON(existing)) {
 853			/*
 854			 * Shouldn't happen we just did a lookup before under
 855			 * delayed_refs->lock.
 856			 */
 857			return ERR_PTR(-EEXIST);
 858		}
 859		head_ref->tracked = true;
 860		/*
 861		 * We reserve the amount of bytes needed to delete csums when
 862		 * adding the ref head and not when adding individual drop refs
 863		 * since the csum items are deleted only after running the last
 864		 * delayed drop ref (the data extent's ref count drops to 0).
 865		 */
 866		if (head_ref->is_data && head_ref->ref_mod < 0) {
 867			delayed_refs->pending_csums += head_ref->num_bytes;
 868			trans->delayed_ref_csum_deletions +=
 869				btrfs_csum_bytes_to_leaves(fs_info, head_ref->num_bytes);
 
 870		}
 871		delayed_refs->num_heads++;
 872		delayed_refs->num_heads_ready++;
 
 873	}
 874	if (qrecord_inserted_ret)
 875		*qrecord_inserted_ret = qrecord_inserted;
 876
 877	return head_ref;
 878}
 879
 880/*
 881 * Initialize the structure which represents a modification to a an extent.
 882 *
 883 * @fs_info:    Internal to the mounted filesystem mount structure.
 884 *
 885 * @ref:	The structure which is going to be initialized.
 886 *
 887 * @bytenr:	The logical address of the extent for which a modification is
 888 *		going to be recorded.
 889 *
 890 * @num_bytes:  Size of the extent whose modification is being recorded.
 891 *
 892 * @ref_root:	The id of the root where this modification has originated, this
 893 *		can be either one of the well-known metadata trees or the
 894 *		subvolume id which references this extent.
 895 *
 896 * @action:	Can be one of BTRFS_ADD_DELAYED_REF/BTRFS_DROP_DELAYED_REF or
 897 *		BTRFS_ADD_DELAYED_EXTENT
 898 *
 899 * @ref_type:	Holds the type of the extent which is being recorded, can be
 900 *		one of BTRFS_SHARED_BLOCK_REF_KEY/BTRFS_TREE_BLOCK_REF_KEY
 901 *		when recording a metadata extent or BTRFS_SHARED_DATA_REF_KEY/
 902 *		BTRFS_EXTENT_DATA_REF_KEY when recording data extent
 903 */
 904static void init_delayed_ref_common(struct btrfs_fs_info *fs_info,
 905				    struct btrfs_delayed_ref_node *ref,
 906				    struct btrfs_ref *generic_ref)
 
 907{
 908	int action = generic_ref->action;
 909	u64 seq = 0;
 910
 911	if (action == BTRFS_ADD_DELAYED_EXTENT)
 912		action = BTRFS_ADD_DELAYED_REF;
 913
 914	if (is_fstree(generic_ref->ref_root))
 915		seq = atomic64_read(&fs_info->tree_mod_seq);
 916
 917	refcount_set(&ref->refs, 1);
 918	ref->bytenr = generic_ref->bytenr;
 919	ref->num_bytes = generic_ref->num_bytes;
 920	ref->ref_mod = 1;
 921	ref->action = action;
 922	ref->seq = seq;
 923	ref->type = btrfs_ref_type(generic_ref);
 924	ref->ref_root = generic_ref->ref_root;
 925	ref->parent = generic_ref->parent;
 926	RB_CLEAR_NODE(&ref->ref_node);
 927	INIT_LIST_HEAD(&ref->add_list);
 
 928
 929	if (generic_ref->type == BTRFS_REF_DATA)
 930		ref->data_ref = generic_ref->data_ref;
 931	else
 932		ref->tree_ref = generic_ref->tree_ref;
 
 
 
 
 933}
 934
 935void btrfs_init_tree_ref(struct btrfs_ref *generic_ref, int level, u64 mod_root,
 936			 bool skip_qgroup)
 937{
 938#ifdef CONFIG_BTRFS_FS_REF_VERIFY
 939	/* If @real_root not set, use @root as fallback */
 940	generic_ref->real_root = mod_root ?: generic_ref->ref_root;
 941#endif
 942	generic_ref->tree_ref.level = level;
 
 943	generic_ref->type = BTRFS_REF_METADATA;
 944	if (skip_qgroup || !(is_fstree(generic_ref->ref_root) &&
 945			     (!mod_root || is_fstree(mod_root))))
 946		generic_ref->skip_qgroup = true;
 947	else
 948		generic_ref->skip_qgroup = false;
 949
 950}
 951
 952void btrfs_init_data_ref(struct btrfs_ref *generic_ref, u64 ino, u64 offset,
 953			 u64 mod_root, bool skip_qgroup)
 954{
 955#ifdef CONFIG_BTRFS_FS_REF_VERIFY
 956	/* If @real_root not set, use @root as fallback */
 957	generic_ref->real_root = mod_root ?: generic_ref->ref_root;
 958#endif
 959	generic_ref->data_ref.objectid = ino;
 
 960	generic_ref->data_ref.offset = offset;
 961	generic_ref->type = BTRFS_REF_DATA;
 962	if (skip_qgroup || !(is_fstree(generic_ref->ref_root) &&
 963			     (!mod_root || is_fstree(mod_root))))
 964		generic_ref->skip_qgroup = true;
 965	else
 966		generic_ref->skip_qgroup = false;
 967}
 968
 969static int add_delayed_ref(struct btrfs_trans_handle *trans,
 970			   struct btrfs_ref *generic_ref,
 971			   struct btrfs_delayed_extent_op *extent_op,
 972			   u64 reserved)
 
 
 
 
 973{
 974	struct btrfs_fs_info *fs_info = trans->fs_info;
 975	struct btrfs_delayed_ref_node *node;
 976	struct btrfs_delayed_ref_head *head_ref;
 977	struct btrfs_delayed_ref_head *new_head_ref;
 978	struct btrfs_delayed_ref_root *delayed_refs;
 979	struct btrfs_qgroup_extent_record *record = NULL;
 980	const unsigned long index = (generic_ref->bytenr >> fs_info->sectorsize_bits);
 981	bool qrecord_reserved = false;
 982	bool qrecord_inserted;
 983	int action = generic_ref->action;
 984	bool merged;
 985	int ret;
 
 
 
 
 
 986
 987	node = kmem_cache_alloc(btrfs_delayed_ref_node_cachep, GFP_NOFS);
 988	if (!node)
 
 
 
 989		return -ENOMEM;
 990
 991	head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
 992	if (!head_ref) {
 993		ret = -ENOMEM;
 994		goto free_node;
 995	}
 996
 997	delayed_refs = &trans->transaction->delayed_refs;
 998
 999	if (btrfs_qgroup_full_accounting(fs_info) && !generic_ref->skip_qgroup) {
1000		record = kzalloc(sizeof(*record), GFP_NOFS);
1001		if (!record) {
1002			ret = -ENOMEM;
1003			goto free_head_ref;
1004		}
1005		if (xa_reserve(&delayed_refs->dirty_extents, index, GFP_NOFS)) {
1006			ret = -ENOMEM;
1007			goto free_record;
1008		}
1009		qrecord_reserved = true;
1010	}
1011
1012	ret = xa_reserve(&delayed_refs->head_refs, index, GFP_NOFS);
1013	if (ret) {
1014		if (qrecord_reserved)
1015			xa_release(&delayed_refs->dirty_extents, index);
1016		goto free_record;
1017	}
1018
1019	init_delayed_ref_common(fs_info, node, generic_ref);
1020	init_delayed_ref_head(head_ref, generic_ref, record, reserved);
 
 
 
 
 
 
 
 
1021	head_ref->extent_op = extent_op;
1022
 
1023	spin_lock(&delayed_refs->lock);
1024
1025	/*
1026	 * insert both the head node and the new ref without dropping
1027	 * the spin lock
1028	 */
1029	new_head_ref = add_delayed_ref_head(trans, head_ref, record,
1030					    action, &qrecord_inserted);
1031	if (IS_ERR(new_head_ref)) {
1032		xa_release(&delayed_refs->head_refs, index);
1033		spin_unlock(&delayed_refs->lock);
1034		ret = PTR_ERR(new_head_ref);
1035		goto free_record;
1036	}
1037	head_ref = new_head_ref;
1038
1039	merged = insert_delayed_ref(trans, head_ref, node);
1040	spin_unlock(&delayed_refs->lock);
1041
1042	/*
1043	 * Need to update the delayed_refs_rsv with any changes we may have
1044	 * made.
1045	 */
1046	btrfs_update_delayed_refs_rsv(trans);
1047
1048	if (generic_ref->type == BTRFS_REF_DATA)
1049		trace_add_delayed_data_ref(trans->fs_info, node);
1050	else
1051		trace_add_delayed_tree_ref(trans->fs_info, node);
1052	if (merged)
1053		kmem_cache_free(btrfs_delayed_ref_node_cachep, node);
1054
1055	if (qrecord_inserted)
1056		return btrfs_qgroup_trace_extent_post(trans, record, generic_ref->bytenr);
1057	return 0;
1058
1059free_record:
1060	kfree(record);
1061free_head_ref:
1062	kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
1063free_node:
1064	kmem_cache_free(btrfs_delayed_ref_node_cachep, node);
1065	return ret;
1066}
1067
1068/*
1069 * Add a delayed tree ref. This does all of the accounting required to make sure
1070 * the delayed ref is eventually processed before this transaction commits.
1071 */
1072int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
1073			       struct btrfs_ref *generic_ref,
1074			       struct btrfs_delayed_extent_op *extent_op)
1075{
1076	ASSERT(generic_ref->type == BTRFS_REF_METADATA && generic_ref->action);
1077	return add_delayed_ref(trans, generic_ref, extent_op, 0);
1078}
1079
1080/*
1081 * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
1082 */
1083int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
1084			       struct btrfs_ref *generic_ref,
1085			       u64 reserved)
1086{
1087	ASSERT(generic_ref->type == BTRFS_REF_DATA && generic_ref->action);
1088	return add_delayed_ref(trans, generic_ref, NULL, reserved);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1089}
1090
1091int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
1092				u64 bytenr, u64 num_bytes, u8 level,
1093				struct btrfs_delayed_extent_op *extent_op)
1094{
1095	const unsigned long index = (bytenr >> trans->fs_info->sectorsize_bits);
1096	struct btrfs_delayed_ref_head *head_ref;
1097	struct btrfs_delayed_ref_head *head_ref_ret;
1098	struct btrfs_delayed_ref_root *delayed_refs;
1099	struct btrfs_ref generic_ref = {
1100		.type = BTRFS_REF_METADATA,
1101		.action = BTRFS_UPDATE_DELAYED_HEAD,
1102		.bytenr = bytenr,
1103		.num_bytes = num_bytes,
1104		.tree_ref.level = level,
1105	};
1106	int ret;
1107
1108	head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
1109	if (!head_ref)
1110		return -ENOMEM;
1111
1112	init_delayed_ref_head(head_ref, &generic_ref, NULL, 0);
 
1113	head_ref->extent_op = extent_op;
1114
1115	delayed_refs = &trans->transaction->delayed_refs;
 
1116
1117	ret = xa_reserve(&delayed_refs->head_refs, index, GFP_NOFS);
1118	if (ret) {
1119		kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
1120		return ret;
1121	}
1122
1123	spin_lock(&delayed_refs->lock);
1124	head_ref_ret = add_delayed_ref_head(trans, head_ref, NULL,
1125					    BTRFS_UPDATE_DELAYED_HEAD, NULL);
1126	if (IS_ERR(head_ref_ret)) {
1127		xa_release(&delayed_refs->head_refs, index);
1128		spin_unlock(&delayed_refs->lock);
1129		kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
1130		return PTR_ERR(head_ref_ret);
1131	}
1132	spin_unlock(&delayed_refs->lock);
1133
1134	/*
1135	 * Need to update the delayed_refs_rsv with any changes we may have
1136	 * made.
1137	 */
1138	btrfs_update_delayed_refs_rsv(trans);
1139	return 0;
1140}
1141
1142void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
1143{
1144	if (refcount_dec_and_test(&ref->refs)) {
1145		WARN_ON(!RB_EMPTY_NODE(&ref->ref_node));
1146		kmem_cache_free(btrfs_delayed_ref_node_cachep, ref);
 
 
 
 
 
 
 
 
 
 
 
1147	}
1148}
1149
1150/*
1151 * This does a simple search for the head node for a given extent.  Returns the
1152 * head node if found, or NULL if not.
1153 */
1154struct btrfs_delayed_ref_head *
1155btrfs_find_delayed_ref_head(const struct btrfs_fs_info *fs_info,
1156			    struct btrfs_delayed_ref_root *delayed_refs,
1157			    u64 bytenr)
1158{
1159	const unsigned long index = (bytenr >> fs_info->sectorsize_bits);
1160
1161	lockdep_assert_held(&delayed_refs->lock);
1162
1163	return xa_load(&delayed_refs->head_refs, index);
1164}
1165
1166static int find_comp(struct btrfs_delayed_ref_node *entry, u64 root, u64 parent)
1167{
1168	int type = parent ? BTRFS_SHARED_BLOCK_REF_KEY : BTRFS_TREE_BLOCK_REF_KEY;
1169
1170	if (type < entry->type)
1171		return -1;
1172	if (type > entry->type)
1173		return 1;
1174
1175	if (type == BTRFS_TREE_BLOCK_REF_KEY) {
1176		if (root < entry->ref_root)
1177			return -1;
1178		if (root > entry->ref_root)
1179			return 1;
1180	} else {
1181		if (parent < entry->parent)
1182			return -1;
1183		if (parent > entry->parent)
1184			return 1;
1185	}
1186	return 0;
1187}
1188
1189/*
1190 * Check to see if a given root/parent reference is attached to the head.  This
1191 * only checks for BTRFS_ADD_DELAYED_REF references that match, as that
1192 * indicates the reference exists for the given root or parent.  This is for
1193 * tree blocks only.
1194 *
1195 * @head: the head of the bytenr we're searching.
1196 * @root: the root objectid of the reference if it is a normal reference.
1197 * @parent: the parent if this is a shared backref.
1198 */
1199bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head,
1200				 u64 root, u64 parent)
1201{
1202	struct rb_node *node;
1203	bool found = false;
1204
1205	lockdep_assert_held(&head->mutex);
1206
1207	spin_lock(&head->lock);
1208	node = head->ref_tree.rb_root.rb_node;
1209	while (node) {
1210		struct btrfs_delayed_ref_node *entry;
1211		int ret;
1212
1213		entry = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
1214		ret = find_comp(entry, root, parent);
1215		if (ret < 0) {
1216			node = node->rb_left;
1217		} else if (ret > 0) {
1218			node = node->rb_right;
1219		} else {
1220			/*
1221			 * We only want to count ADD actions, as drops mean the
1222			 * ref doesn't exist.
1223			 */
1224			if (entry->action == BTRFS_ADD_DELAYED_REF)
1225				found = true;
1226			break;
1227		}
1228	}
1229	spin_unlock(&head->lock);
1230	return found;
1231}
1232
1233void btrfs_destroy_delayed_refs(struct btrfs_transaction *trans)
1234{
1235	struct btrfs_delayed_ref_root *delayed_refs = &trans->delayed_refs;
1236	struct btrfs_fs_info *fs_info = trans->fs_info;
1237
1238	spin_lock(&delayed_refs->lock);
1239	while (true) {
1240		struct btrfs_delayed_ref_head *head;
1241		struct rb_node *n;
1242		bool pin_bytes = false;
1243
1244		head = find_first_ref_head(delayed_refs);
1245		if (!head)
1246			break;
1247
1248		if (!btrfs_delayed_ref_lock(delayed_refs, head))
1249			continue;
1250
1251		spin_lock(&head->lock);
1252		while ((n = rb_first_cached(&head->ref_tree)) != NULL) {
1253			struct btrfs_delayed_ref_node *ref;
1254
1255			ref = rb_entry(n, struct btrfs_delayed_ref_node, ref_node);
1256			drop_delayed_ref(fs_info, delayed_refs, head, ref);
1257		}
1258		if (head->must_insert_reserved)
1259			pin_bytes = true;
1260		btrfs_free_delayed_extent_op(head->extent_op);
1261		btrfs_delete_ref_head(fs_info, delayed_refs, head);
1262		spin_unlock(&head->lock);
1263		spin_unlock(&delayed_refs->lock);
1264		mutex_unlock(&head->mutex);
1265
1266		if (pin_bytes) {
1267			struct btrfs_block_group *bg;
1268
1269			bg = btrfs_lookup_block_group(fs_info, head->bytenr);
1270			if (WARN_ON_ONCE(bg == NULL)) {
1271				/*
1272				 * Unexpected and there's nothing we can do here
1273				 * because we are in a transaction abort path,
1274				 * so any errors can only be ignored or reported
1275				 * while attempting to cleanup all resources.
1276				 */
1277				btrfs_err(fs_info,
1278"block group for delayed ref at %llu was not found while destroying ref head",
1279					  head->bytenr);
1280			} else {
1281				spin_lock(&bg->space_info->lock);
1282				spin_lock(&bg->lock);
1283				bg->pinned += head->num_bytes;
1284				btrfs_space_info_update_bytes_pinned(fs_info,
1285								     bg->space_info,
1286								     head->num_bytes);
1287				bg->reserved -= head->num_bytes;
1288				bg->space_info->bytes_reserved -= head->num_bytes;
1289				spin_unlock(&bg->lock);
1290				spin_unlock(&bg->space_info->lock);
1291
1292				btrfs_put_block_group(bg);
1293			}
1294
1295			btrfs_error_unpin_extent_range(fs_info, head->bytenr,
1296				head->bytenr + head->num_bytes - 1);
1297		}
1298		btrfs_cleanup_ref_head_accounting(fs_info, delayed_refs, head);
1299		btrfs_put_delayed_ref_head(head);
1300		cond_resched();
1301		spin_lock(&delayed_refs->lock);
1302	}
1303	btrfs_qgroup_destroy_extent_records(trans);
1304
1305	spin_unlock(&delayed_refs->lock);
1306}
1307
1308void __cold btrfs_delayed_ref_exit(void)
1309{
1310	kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
1311	kmem_cache_destroy(btrfs_delayed_ref_node_cachep);
 
1312	kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
1313}
1314
1315int __init btrfs_delayed_ref_init(void)
1316{
1317	btrfs_delayed_ref_head_cachep = KMEM_CACHE(btrfs_delayed_ref_head, 0);
1318	if (!btrfs_delayed_ref_head_cachep)
1319		goto fail;
1320
1321	btrfs_delayed_ref_node_cachep = KMEM_CACHE(btrfs_delayed_ref_node, 0);
1322	if (!btrfs_delayed_ref_node_cachep)
 
 
 
 
1323		goto fail;
1324
1325	btrfs_delayed_extent_op_cachep = KMEM_CACHE(btrfs_delayed_extent_op, 0);
1326	if (!btrfs_delayed_extent_op_cachep)
1327		goto fail;
1328
1329	return 0;
1330fail:
1331	btrfs_delayed_ref_exit();
1332	return -ENOMEM;
1333}