1/*
   2 * Copyright (C) 2009 Oracle.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public
   6 * License v2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 * General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public
  14 * License along with this program; if not, write to the
  15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16 * Boston, MA 021110-1307, USA.
  17 */
  18
  19#include <linux/sched.h>
  20#include <linux/pagemap.h>
  21#include <linux/writeback.h>
  22#include <linux/blkdev.h>
  23#include <linux/rbtree.h>
  24#include <linux/slab.h>
  25#include "ctree.h"
  26#include "disk-io.h"
  27#include "transaction.h"
  28#include "volumes.h"
  29#include "locking.h"
  30#include "btrfs_inode.h"
  31#include "async-thread.h"
  32#include "free-space-cache.h"
  33#include "inode-map.h"
  34
  35/*
  36 * backref_node, mapping_node and tree_block start with this
  37 */
  38struct tree_entry {
  39	struct rb_node rb_node;
  40	u64 bytenr;
  41};
  42
  43/*
  44 * present a tree block in the backref cache
  45 */
  46struct backref_node {
  47	struct rb_node rb_node;
  48	u64 bytenr;
  49
  50	u64 new_bytenr;
  51	/* objectid of tree block owner, can be not uptodate */
  52	u64 owner;
  53	/* link to pending, changed or detached list */
  54	struct list_head list;
  55	/* list of upper level blocks reference this block */
  56	struct list_head upper;
  57	/* list of child blocks in the cache */
  58	struct list_head lower;
  59	/* NULL if this node is not tree root */
  60	struct btrfs_root *root;
  61	/* extent buffer got by COW the block */
  62	struct extent_buffer *eb;
  63	/* level of tree block */
  64	unsigned int level:8;
  65	/* is the block in non-reference counted tree */
  66	unsigned int cowonly:1;
  67	/* 1 if no child node in the cache */
  68	unsigned int lowest:1;
  69	/* is the extent buffer locked */
  70	unsigned int locked:1;
  71	/* has the block been processed */
  72	unsigned int processed:1;
  73	/* have backrefs of this block been checked */
  74	unsigned int checked:1;
  75	/*
  76	 * 1 if corresponding block has been cowed but some upper
  77	 * level block pointers may not point to the new location
  78	 */
  79	unsigned int pending:1;
  80	/*
  81	 * 1 if the backref node isn't connected to any other
  82	 * backref node.
  83	 */
  84	unsigned int detached:1;
  85};
  86
  87/*
  88 * present a block pointer in the backref cache
  89 */
  90struct backref_edge {
  91	struct list_head list[2];
  92	struct backref_node *node[2];
  93};
  94
  95#define LOWER	0
  96#define UPPER	1
  97#define RELOCATION_RESERVED_NODES	256
  98
  99struct backref_cache {
 100	/* red black tree of all backref nodes in the cache */
 101	struct rb_root rb_root;
 102	/* for passing backref nodes to btrfs_reloc_cow_block */
 103	struct backref_node *path[BTRFS_MAX_LEVEL];
 104	/*
 105	 * list of blocks that have been cowed but some block
 106	 * pointers in upper level blocks may not reflect the
 107	 * new location
 108	 */
 109	struct list_head pending[BTRFS_MAX_LEVEL];
 110	/* list of backref nodes with no child node */
 111	struct list_head leaves;
 112	/* list of blocks that have been cowed in current transaction */
 113	struct list_head changed;
 114	/* list of detached backref node. */
 115	struct list_head detached;
 116
 117	u64 last_trans;
 118
 119	int nr_nodes;
 120	int nr_edges;
 121};
 122
 123/*
 124 * map address of tree root to tree
 125 */
 126struct mapping_node {
 127	struct rb_node rb_node;
 128	u64 bytenr;
 129	void *data;
 130};
 131
 132struct mapping_tree {
 133	struct rb_root rb_root;
 134	spinlock_t lock;
 135};
 136
 137/*
 138 * present a tree block to process
 139 */
 140struct tree_block {
 141	struct rb_node rb_node;
 142	u64 bytenr;
 143	struct btrfs_key key;
 144	unsigned int level:8;
 145	unsigned int key_ready:1;
 146};
 147
 148#define MAX_EXTENTS 128
 149
 150struct file_extent_cluster {
 151	u64 start;
 152	u64 end;
 153	u64 boundary[MAX_EXTENTS];
 154	unsigned int nr;
 155};
 156
 157struct reloc_control {
 158	/* block group to relocate */
 159	struct btrfs_block_group_cache *block_group;
 160	/* extent tree */
 161	struct btrfs_root *extent_root;
 162	/* inode for moving data */
 163	struct inode *data_inode;
 164
 165	struct btrfs_block_rsv *block_rsv;
 166
 167	struct backref_cache backref_cache;
 168
 169	struct file_extent_cluster cluster;
 170	/* tree blocks have been processed */
 171	struct extent_io_tree processed_blocks;
 172	/* map start of tree root to corresponding reloc tree */
 173	struct mapping_tree reloc_root_tree;
 174	/* list of reloc trees */
 175	struct list_head reloc_roots;
 176	/* size of metadata reservation for merging reloc trees */
 177	u64 merging_rsv_size;
 178	/* size of relocated tree nodes */
 179	u64 nodes_relocated;
 180	/* reserved size for block group relocation*/
 181	u64 reserved_bytes;
 182
 183	u64 search_start;
 184	u64 extents_found;
 185
 186	unsigned int stage:8;
 187	unsigned int create_reloc_tree:1;
 188	unsigned int merge_reloc_tree:1;
 189	unsigned int found_file_extent:1;
 
 190};
 191
 192/* stages of data relocation */
 193#define MOVE_DATA_EXTENTS	0
 194#define UPDATE_DATA_PTRS	1
 195
 196static void remove_backref_node(struct backref_cache *cache,
 197				struct backref_node *node);
 198static void __mark_block_processed(struct reloc_control *rc,
 199				   struct backref_node *node);
 200
 201static void mapping_tree_init(struct mapping_tree *tree)
 202{
 203	tree->rb_root = RB_ROOT;
 204	spin_lock_init(&tree->lock);
 205}
 206
 207static void backref_cache_init(struct backref_cache *cache)
 208{
 209	int i;
 210	cache->rb_root = RB_ROOT;
 211	for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 212		INIT_LIST_HEAD(&cache->pending[i]);
 213	INIT_LIST_HEAD(&cache->changed);
 214	INIT_LIST_HEAD(&cache->detached);
 215	INIT_LIST_HEAD(&cache->leaves);
 216}
 217
 218static void backref_cache_cleanup(struct backref_cache *cache)
 219{
 220	struct backref_node *node;
 221	int i;
 222
 223	while (!list_empty(&cache->detached)) {
 224		node = list_entry(cache->detached.next,
 225				  struct backref_node, list);
 226		remove_backref_node(cache, node);
 227	}
 228
 229	while (!list_empty(&cache->leaves)) {
 230		node = list_entry(cache->leaves.next,
 231				  struct backref_node, lower);
 232		remove_backref_node(cache, node);
 233	}
 234
 235	cache->last_trans = 0;
 236
 237	for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 238		BUG_ON(!list_empty(&cache->pending[i]));
 239	BUG_ON(!list_empty(&cache->changed));
 240	BUG_ON(!list_empty(&cache->detached));
 241	BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
 242	BUG_ON(cache->nr_nodes);
 243	BUG_ON(cache->nr_edges);
 244}
 245
 246static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 247{
 248	struct backref_node *node;
 249
 250	node = kzalloc(sizeof(*node), GFP_NOFS);
 251	if (node) {
 252		INIT_LIST_HEAD(&node->list);
 253		INIT_LIST_HEAD(&node->upper);
 254		INIT_LIST_HEAD(&node->lower);
 255		RB_CLEAR_NODE(&node->rb_node);
 256		cache->nr_nodes++;
 257	}
 258	return node;
 259}
 260
 261static void free_backref_node(struct backref_cache *cache,
 262			      struct backref_node *node)
 263{
 264	if (node) {
 265		cache->nr_nodes--;
 266		kfree(node);
 267	}
 268}
 269
 270static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 271{
 272	struct backref_edge *edge;
 273
 274	edge = kzalloc(sizeof(*edge), GFP_NOFS);
 275	if (edge)
 276		cache->nr_edges++;
 277	return edge;
 278}
 279
 280static void free_backref_edge(struct backref_cache *cache,
 281			      struct backref_edge *edge)
 282{
 283	if (edge) {
 284		cache->nr_edges--;
 285		kfree(edge);
 286	}
 287}
 288
 289static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 290				   struct rb_node *node)
 291{
 292	struct rb_node **p = &root->rb_node;
 293	struct rb_node *parent = NULL;
 294	struct tree_entry *entry;
 295
 296	while (*p) {
 297		parent = *p;
 298		entry = rb_entry(parent, struct tree_entry, rb_node);
 299
 300		if (bytenr < entry->bytenr)
 301			p = &(*p)->rb_left;
 302		else if (bytenr > entry->bytenr)
 303			p = &(*p)->rb_right;
 304		else
 305			return parent;
 306	}
 307
 308	rb_link_node(node, parent, p);
 309	rb_insert_color(node, root);
 310	return NULL;
 311}
 312
 313static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 314{
 315	struct rb_node *n = root->rb_node;
 316	struct tree_entry *entry;
 317
 318	while (n) {
 319		entry = rb_entry(n, struct tree_entry, rb_node);
 320
 321		if (bytenr < entry->bytenr)
 322			n = n->rb_left;
 323		else if (bytenr > entry->bytenr)
 324			n = n->rb_right;
 325		else
 326			return n;
 327	}
 328	return NULL;
 329}
 330
 331static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
 332{
 333
 334	struct btrfs_fs_info *fs_info = NULL;
 335	struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 336					      rb_node);
 337	if (bnode->root)
 338		fs_info = bnode->root->fs_info;
 339	btrfs_panic(fs_info, errno, "Inconsistency in backref cache "
 340		    "found at offset %llu", bytenr);
 341}
 342
 343/*
 344 * walk up backref nodes until reach node presents tree root
 345 */
 346static struct backref_node *walk_up_backref(struct backref_node *node,
 347					    struct backref_edge *edges[],
 348					    int *index)
 349{
 350	struct backref_edge *edge;
 351	int idx = *index;
 352
 353	while (!list_empty(&node->upper)) {
 354		edge = list_entry(node->upper.next,
 355				  struct backref_edge, list[LOWER]);
 356		edges[idx++] = edge;
 357		node = edge->node[UPPER];
 358	}
 359	BUG_ON(node->detached);
 360	*index = idx;
 361	return node;
 362}
 363
 364/*
 365 * walk down backref nodes to find start of next reference path
 366 */
 367static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 368					      int *index)
 369{
 370	struct backref_edge *edge;
 371	struct backref_node *lower;
 372	int idx = *index;
 373
 374	while (idx > 0) {
 375		edge = edges[idx - 1];
 376		lower = edge->node[LOWER];
 377		if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 378			idx--;
 379			continue;
 380		}
 381		edge = list_entry(edge->list[LOWER].next,
 382				  struct backref_edge, list[LOWER]);
 383		edges[idx - 1] = edge;
 384		*index = idx;
 385		return edge->node[UPPER];
 386	}
 387	*index = 0;
 388	return NULL;
 389}
 390
 391static void unlock_node_buffer(struct backref_node *node)
 392{
 393	if (node->locked) {
 394		btrfs_tree_unlock(node->eb);
 395		node->locked = 0;
 396	}
 397}
 398
 399static void drop_node_buffer(struct backref_node *node)
 400{
 401	if (node->eb) {
 402		unlock_node_buffer(node);
 403		free_extent_buffer(node->eb);
 404		node->eb = NULL;
 405	}
 406}
 407
 408static void drop_backref_node(struct backref_cache *tree,
 409			      struct backref_node *node)
 410{
 411	BUG_ON(!list_empty(&node->upper));
 412
 413	drop_node_buffer(node);
 414	list_del(&node->list);
 415	list_del(&node->lower);
 416	if (!RB_EMPTY_NODE(&node->rb_node))
 417		rb_erase(&node->rb_node, &tree->rb_root);
 418	free_backref_node(tree, node);
 419}
 420
 421/*
 422 * remove a backref node from the backref cache
 423 */
 424static void remove_backref_node(struct backref_cache *cache,
 425				struct backref_node *node)
 426{
 427	struct backref_node *upper;
 428	struct backref_edge *edge;
 429
 430	if (!node)
 431		return;
 432
 433	BUG_ON(!node->lowest && !node->detached);
 434	while (!list_empty(&node->upper)) {
 435		edge = list_entry(node->upper.next, struct backref_edge,
 436				  list[LOWER]);
 437		upper = edge->node[UPPER];
 438		list_del(&edge->list[LOWER]);
 439		list_del(&edge->list[UPPER]);
 440		free_backref_edge(cache, edge);
 441
 442		if (RB_EMPTY_NODE(&upper->rb_node)) {
 443			BUG_ON(!list_empty(&node->upper));
 444			drop_backref_node(cache, node);
 445			node = upper;
 446			node->lowest = 1;
 447			continue;
 448		}
 449		/*
 450		 * add the node to leaf node list if no other
 451		 * child block cached.
 452		 */
 453		if (list_empty(&upper->lower)) {
 454			list_add_tail(&upper->lower, &cache->leaves);
 455			upper->lowest = 1;
 456		}
 457	}
 458
 459	drop_backref_node(cache, node);
 460}
 461
 462static void update_backref_node(struct backref_cache *cache,
 463				struct backref_node *node, u64 bytenr)
 464{
 465	struct rb_node *rb_node;
 466	rb_erase(&node->rb_node, &cache->rb_root);
 467	node->bytenr = bytenr;
 468	rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 469	if (rb_node)
 470		backref_tree_panic(rb_node, -EEXIST, bytenr);
 471}
 472
 473/*
 474 * update backref cache after a transaction commit
 475 */
 476static int update_backref_cache(struct btrfs_trans_handle *trans,
 477				struct backref_cache *cache)
 478{
 479	struct backref_node *node;
 480	int level = 0;
 481
 482	if (cache->last_trans == 0) {
 483		cache->last_trans = trans->transid;
 484		return 0;
 485	}
 486
 487	if (cache->last_trans == trans->transid)
 488		return 0;
 489
 490	/*
 491	 * detached nodes are used to avoid unnecessary backref
 492	 * lookup. transaction commit changes the extent tree.
 493	 * so the detached nodes are no longer useful.
 494	 */
 495	while (!list_empty(&cache->detached)) {
 496		node = list_entry(cache->detached.next,
 497				  struct backref_node, list);
 498		remove_backref_node(cache, node);
 499	}
 500
 501	while (!list_empty(&cache->changed)) {
 502		node = list_entry(cache->changed.next,
 503				  struct backref_node, list);
 504		list_del_init(&node->list);
 505		BUG_ON(node->pending);
 506		update_backref_node(cache, node, node->new_bytenr);
 507	}
 508
 509	/*
 510	 * some nodes can be left in the pending list if there were
 511	 * errors during processing the pending nodes.
 512	 */
 513	for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 514		list_for_each_entry(node, &cache->pending[level], list) {
 515			BUG_ON(!node->pending);
 516			if (node->bytenr == node->new_bytenr)
 517				continue;
 518			update_backref_node(cache, node, node->new_bytenr);
 519		}
 520	}
 521
 522	cache->last_trans = 0;
 523	return 1;
 524}
 525
 526
 527static int should_ignore_root(struct btrfs_root *root)
 528{
 529	struct btrfs_root *reloc_root;
 530
 531	if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 532		return 0;
 533
 534	reloc_root = root->reloc_root;
 535	if (!reloc_root)
 536		return 0;
 537
 538	if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 539	    root->fs_info->running_transaction->transid - 1)
 540		return 0;
 541	/*
 542	 * if there is reloc tree and it was created in previous
 543	 * transaction backref lookup can find the reloc tree,
 544	 * so backref node for the fs tree root is useless for
 545	 * relocation.
 546	 */
 547	return 1;
 548}
 549/*
 550 * find reloc tree by address of tree root
 551 */
 552static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 553					  u64 bytenr)
 554{
 555	struct rb_node *rb_node;
 556	struct mapping_node *node;
 557	struct btrfs_root *root = NULL;
 558
 559	spin_lock(&rc->reloc_root_tree.lock);
 560	rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 561	if (rb_node) {
 562		node = rb_entry(rb_node, struct mapping_node, rb_node);
 563		root = (struct btrfs_root *)node->data;
 564	}
 565	spin_unlock(&rc->reloc_root_tree.lock);
 566	return root;
 567}
 568
 569static int is_cowonly_root(u64 root_objectid)
 570{
 571	if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 572	    root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 573	    root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 574	    root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 575	    root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 576	    root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
 577	    root_objectid == BTRFS_UUID_TREE_OBJECTID ||
 578	    root_objectid == BTRFS_QUOTA_TREE_OBJECTID ||
 579	    root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
 580		return 1;
 581	return 0;
 582}
 583
 584static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 585					u64 root_objectid)
 586{
 587	struct btrfs_key key;
 588
 589	key.objectid = root_objectid;
 590	key.type = BTRFS_ROOT_ITEM_KEY;
 591	if (is_cowonly_root(root_objectid))
 592		key.offset = 0;
 593	else
 594		key.offset = (u64)-1;
 595
 596	return btrfs_get_fs_root(fs_info, &key, false);
 597}
 598
 599#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 600static noinline_for_stack
 601struct btrfs_root *find_tree_root(struct reloc_control *rc,
 602				  struct extent_buffer *leaf,
 603				  struct btrfs_extent_ref_v0 *ref0)
 604{
 605	struct btrfs_root *root;
 606	u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 607	u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 608
 609	BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 610
 611	root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 612	BUG_ON(IS_ERR(root));
 613
 614	if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 615	    generation != btrfs_root_generation(&root->root_item))
 616		return NULL;
 617
 618	return root;
 619}
 620#endif
 621
 622static noinline_for_stack
 623int find_inline_backref(struct extent_buffer *leaf, int slot,
 624			unsigned long *ptr, unsigned long *end)
 625{
 626	struct btrfs_key key;
 627	struct btrfs_extent_item *ei;
 628	struct btrfs_tree_block_info *bi;
 629	u32 item_size;
 630
 631	btrfs_item_key_to_cpu(leaf, &key, slot);
 632
 633	item_size = btrfs_item_size_nr(leaf, slot);
 634#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 635	if (item_size < sizeof(*ei)) {
 636		WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 637		return 1;
 638	}
 639#endif
 640	ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 641	WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 642		  BTRFS_EXTENT_FLAG_TREE_BLOCK));
 643
 644	if (key.type == BTRFS_EXTENT_ITEM_KEY &&
 645	    item_size <= sizeof(*ei) + sizeof(*bi)) {
 646		WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 647		return 1;
 648	}
 649	if (key.type == BTRFS_METADATA_ITEM_KEY &&
 650	    item_size <= sizeof(*ei)) {
 651		WARN_ON(item_size < sizeof(*ei));
 652		return 1;
 653	}
 654
 655	if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 656		bi = (struct btrfs_tree_block_info *)(ei + 1);
 657		*ptr = (unsigned long)(bi + 1);
 658	} else {
 659		*ptr = (unsigned long)(ei + 1);
 660	}
 661	*end = (unsigned long)ei + item_size;
 662	return 0;
 663}
 664
 665/*
 666 * build backref tree for a given tree block. root of the backref tree
 667 * corresponds the tree block, leaves of the backref tree correspond
 668 * roots of b-trees that reference the tree block.
 669 *
 670 * the basic idea of this function is check backrefs of a given block
 671 * to find upper level blocks that refernece the block, and then check
 672 * bakcrefs of these upper level blocks recursively. the recursion stop
 673 * when tree root is reached or backrefs for the block is cached.
 674 *
 675 * NOTE: if we find backrefs for a block are cached, we know backrefs
 676 * for all upper level blocks that directly/indirectly reference the
 677 * block are also cached.
 678 */
 679static noinline_for_stack
 680struct backref_node *build_backref_tree(struct reloc_control *rc,
 681					struct btrfs_key *node_key,
 682					int level, u64 bytenr)
 683{
 684	struct backref_cache *cache = &rc->backref_cache;
 685	struct btrfs_path *path1;
 686	struct btrfs_path *path2;
 687	struct extent_buffer *eb;
 688	struct btrfs_root *root;
 689	struct backref_node *cur;
 690	struct backref_node *upper;
 691	struct backref_node *lower;
 692	struct backref_node *node = NULL;
 693	struct backref_node *exist = NULL;
 694	struct backref_edge *edge;
 695	struct rb_node *rb_node;
 696	struct btrfs_key key;
 697	unsigned long end;
 698	unsigned long ptr;
 699	LIST_HEAD(list);
 700	LIST_HEAD(useless);
 701	int cowonly;
 702	int ret;
 703	int err = 0;
 704	bool need_check = true;
 705
 706	path1 = btrfs_alloc_path();
 707	path2 = btrfs_alloc_path();
 708	if (!path1 || !path2) {
 709		err = -ENOMEM;
 710		goto out;
 711	}
 712	path1->reada = READA_FORWARD;
 713	path2->reada = READA_FORWARD;
 714
 715	node = alloc_backref_node(cache);
 716	if (!node) {
 717		err = -ENOMEM;
 718		goto out;
 719	}
 720
 721	node->bytenr = bytenr;
 722	node->level = level;
 723	node->lowest = 1;
 724	cur = node;
 725again:
 726	end = 0;
 727	ptr = 0;
 728	key.objectid = cur->bytenr;
 729	key.type = BTRFS_METADATA_ITEM_KEY;
 730	key.offset = (u64)-1;
 731
 732	path1->search_commit_root = 1;
 733	path1->skip_locking = 1;
 734	ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 735				0, 0);
 736	if (ret < 0) {
 737		err = ret;
 738		goto out;
 739	}
 740	ASSERT(ret);
 741	ASSERT(path1->slots[0]);
 742
 743	path1->slots[0]--;
 744
 745	WARN_ON(cur->checked);
 746	if (!list_empty(&cur->upper)) {
 747		/*
 748		 * the backref was added previously when processing
 749		 * backref of type BTRFS_TREE_BLOCK_REF_KEY
 750		 */
 751		ASSERT(list_is_singular(&cur->upper));
 752		edge = list_entry(cur->upper.next, struct backref_edge,
 753				  list[LOWER]);
 754		ASSERT(list_empty(&edge->list[UPPER]));
 755		exist = edge->node[UPPER];
 756		/*
 757		 * add the upper level block to pending list if we need
 758		 * check its backrefs
 759		 */
 760		if (!exist->checked)
 761			list_add_tail(&edge->list[UPPER], &list);
 762	} else {
 763		exist = NULL;
 764	}
 765
 766	while (1) {
 767		cond_resched();
 768		eb = path1->nodes[0];
 769
 770		if (ptr >= end) {
 771			if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 772				ret = btrfs_next_leaf(rc->extent_root, path1);
 773				if (ret < 0) {
 774					err = ret;
 775					goto out;
 776				}
 777				if (ret > 0)
 778					break;
 779				eb = path1->nodes[0];
 780			}
 781
 782			btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 783			if (key.objectid != cur->bytenr) {
 784				WARN_ON(exist);
 785				break;
 786			}
 787
 788			if (key.type == BTRFS_EXTENT_ITEM_KEY ||
 789			    key.type == BTRFS_METADATA_ITEM_KEY) {
 790				ret = find_inline_backref(eb, path1->slots[0],
 791							  &ptr, &end);
 792				if (ret)
 793					goto next;
 794			}
 795		}
 796
 797		if (ptr < end) {
 798			/* update key for inline back ref */
 799			struct btrfs_extent_inline_ref *iref;
 800			iref = (struct btrfs_extent_inline_ref *)ptr;
 801			key.type = btrfs_extent_inline_ref_type(eb, iref);
 802			key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 803			WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 804				key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 805		}
 806
 807		if (exist &&
 808		    ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 809		      exist->owner == key.offset) ||
 810		     (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 811		      exist->bytenr == key.offset))) {
 812			exist = NULL;
 813			goto next;
 814		}
 815
 816#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 817		if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 818		    key.type == BTRFS_EXTENT_REF_V0_KEY) {
 819			if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 820				struct btrfs_extent_ref_v0 *ref0;
 821				ref0 = btrfs_item_ptr(eb, path1->slots[0],
 822						struct btrfs_extent_ref_v0);
 823				if (key.objectid == key.offset) {
 824					root = find_tree_root(rc, eb, ref0);
 825					if (root && !should_ignore_root(root))
 826						cur->root = root;
 827					else
 828						list_add(&cur->list, &useless);
 829					break;
 830				}
 831				if (is_cowonly_root(btrfs_ref_root_v0(eb,
 832								      ref0)))
 833					cur->cowonly = 1;
 834			}
 835#else
 836		ASSERT(key.type != BTRFS_EXTENT_REF_V0_KEY);
 837		if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 838#endif
 839			if (key.objectid == key.offset) {
 840				/*
 841				 * only root blocks of reloc trees use
 842				 * backref of this type.
 843				 */
 844				root = find_reloc_root(rc, cur->bytenr);
 845				ASSERT(root);
 846				cur->root = root;
 847				break;
 848			}
 849
 850			edge = alloc_backref_edge(cache);
 851			if (!edge) {
 852				err = -ENOMEM;
 853				goto out;
 854			}
 855			rb_node = tree_search(&cache->rb_root, key.offset);
 856			if (!rb_node) {
 857				upper = alloc_backref_node(cache);
 858				if (!upper) {
 859					free_backref_edge(cache, edge);
 860					err = -ENOMEM;
 861					goto out;
 862				}
 863				upper->bytenr = key.offset;
 864				upper->level = cur->level + 1;
 865				/*
 866				 *  backrefs for the upper level block isn't
 867				 *  cached, add the block to pending list
 868				 */
 869				list_add_tail(&edge->list[UPPER], &list);
 870			} else {
 871				upper = rb_entry(rb_node, struct backref_node,
 872						 rb_node);
 873				ASSERT(upper->checked);
 874				INIT_LIST_HEAD(&edge->list[UPPER]);
 875			}
 876			list_add_tail(&edge->list[LOWER], &cur->upper);
 877			edge->node[LOWER] = cur;
 878			edge->node[UPPER] = upper;
 879
 880			goto next;
 881		} else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 882			goto next;
 883		}
 884
 885		/* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 886		root = read_fs_root(rc->extent_root->fs_info, key.offset);
 887		if (IS_ERR(root)) {
 888			err = PTR_ERR(root);
 889			goto out;
 890		}
 891
 892		if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 893			cur->cowonly = 1;
 894
 895		if (btrfs_root_level(&root->root_item) == cur->level) {
 896			/* tree root */
 897			ASSERT(btrfs_root_bytenr(&root->root_item) ==
 898			       cur->bytenr);
 899			if (should_ignore_root(root))
 900				list_add(&cur->list, &useless);
 901			else
 902				cur->root = root;
 903			break;
 904		}
 905
 906		level = cur->level + 1;
 907
 908		/*
 909		 * searching the tree to find upper level blocks
 910		 * reference the block.
 911		 */
 912		path2->search_commit_root = 1;
 913		path2->skip_locking = 1;
 914		path2->lowest_level = level;
 915		ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 916		path2->lowest_level = 0;
 917		if (ret < 0) {
 918			err = ret;
 919			goto out;
 920		}
 921		if (ret > 0 && path2->slots[level] > 0)
 922			path2->slots[level]--;
 923
 924		eb = path2->nodes[level];
 925		WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 926			cur->bytenr);
 927
 928		lower = cur;
 929		need_check = true;
 930		for (; level < BTRFS_MAX_LEVEL; level++) {
 931			if (!path2->nodes[level]) {
 932				ASSERT(btrfs_root_bytenr(&root->root_item) ==
 933				       lower->bytenr);
 934				if (should_ignore_root(root))
 935					list_add(&lower->list, &useless);
 936				else
 937					lower->root = root;
 938				break;
 939			}
 940
 941			edge = alloc_backref_edge(cache);
 942			if (!edge) {
 943				err = -ENOMEM;
 944				goto out;
 945			}
 946
 947			eb = path2->nodes[level];
 948			rb_node = tree_search(&cache->rb_root, eb->start);
 949			if (!rb_node) {
 950				upper = alloc_backref_node(cache);
 951				if (!upper) {
 952					free_backref_edge(cache, edge);
 953					err = -ENOMEM;
 954					goto out;
 955				}
 956				upper->bytenr = eb->start;
 957				upper->owner = btrfs_header_owner(eb);
 958				upper->level = lower->level + 1;
 959				if (!test_bit(BTRFS_ROOT_REF_COWS,
 960					      &root->state))
 961					upper->cowonly = 1;
 962
 963				/*
 964				 * if we know the block isn't shared
 965				 * we can void checking its backrefs.
 966				 */
 967				if (btrfs_block_can_be_shared(root, eb))
 968					upper->checked = 0;
 969				else
 970					upper->checked = 1;
 971
 972				/*
 973				 * add the block to pending list if we
 974				 * need check its backrefs, we only do this once
 975				 * while walking up a tree as we will catch
 976				 * anything else later on.
 
 
 977				 */
 978				if (!upper->checked && need_check) {
 979					need_check = false;
 980					list_add_tail(&edge->list[UPPER],
 981						      &list);
 982				} else {
 983					if (upper->checked)
 984						need_check = true;
 985					INIT_LIST_HEAD(&edge->list[UPPER]);
 986				}
 987			} else {
 988				upper = rb_entry(rb_node, struct backref_node,
 989						 rb_node);
 990				ASSERT(upper->checked);
 991				INIT_LIST_HEAD(&edge->list[UPPER]);
 992				if (!upper->owner)
 993					upper->owner = btrfs_header_owner(eb);
 994			}
 995			list_add_tail(&edge->list[LOWER], &lower->upper);
 996			edge->node[LOWER] = lower;
 997			edge->node[UPPER] = upper;
 998
 999			if (rb_node)
1000				break;
1001			lower = upper;
1002			upper = NULL;
1003		}
1004		btrfs_release_path(path2);
1005next:
1006		if (ptr < end) {
1007			ptr += btrfs_extent_inline_ref_size(key.type);
1008			if (ptr >= end) {
1009				WARN_ON(ptr > end);
1010				ptr = 0;
1011				end = 0;
1012			}
1013		}
1014		if (ptr >= end)
1015			path1->slots[0]++;
1016	}
1017	btrfs_release_path(path1);
1018
1019	cur->checked = 1;
1020	WARN_ON(exist);
1021
1022	/* the pending list isn't empty, take the first block to process */
1023	if (!list_empty(&list)) {
1024		edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1025		list_del_init(&edge->list[UPPER]);
1026		cur = edge->node[UPPER];
1027		goto again;
1028	}
1029
1030	/*
1031	 * everything goes well, connect backref nodes and insert backref nodes
1032	 * into the cache.
1033	 */
1034	ASSERT(node->checked);
1035	cowonly = node->cowonly;
1036	if (!cowonly) {
1037		rb_node = tree_insert(&cache->rb_root, node->bytenr,
1038				      &node->rb_node);
1039		if (rb_node)
1040			backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1041		list_add_tail(&node->lower, &cache->leaves);
1042	}
1043
1044	list_for_each_entry(edge, &node->upper, list[LOWER])
1045		list_add_tail(&edge->list[UPPER], &list);
1046
1047	while (!list_empty(&list)) {
1048		edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1049		list_del_init(&edge->list[UPPER]);
1050		upper = edge->node[UPPER];
1051		if (upper->detached) {
1052			list_del(&edge->list[LOWER]);
1053			lower = edge->node[LOWER];
1054			free_backref_edge(cache, edge);
1055			if (list_empty(&lower->upper))
1056				list_add(&lower->list, &useless);
1057			continue;
1058		}
1059
1060		if (!RB_EMPTY_NODE(&upper->rb_node)) {
1061			if (upper->lowest) {
1062				list_del_init(&upper->lower);
1063				upper->lowest = 0;
1064			}
1065
1066			list_add_tail(&edge->list[UPPER], &upper->lower);
1067			continue;
1068		}
1069
1070		if (!upper->checked) {
1071			/*
1072			 * Still want to blow up for developers since this is a
1073			 * logic bug.
1074			 */
1075			ASSERT(0);
1076			err = -EINVAL;
1077			goto out;
1078		}
1079		if (cowonly != upper->cowonly) {
1080			ASSERT(0);
1081			err = -EINVAL;
1082			goto out;
1083		}
1084
1085		if (!cowonly) {
1086			rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1087					      &upper->rb_node);
1088			if (rb_node)
1089				backref_tree_panic(rb_node, -EEXIST,
1090						   upper->bytenr);
1091		}
1092
1093		list_add_tail(&edge->list[UPPER], &upper->lower);
1094
1095		list_for_each_entry(edge, &upper->upper, list[LOWER])
1096			list_add_tail(&edge->list[UPPER], &list);
1097	}
1098	/*
1099	 * process useless backref nodes. backref nodes for tree leaves
1100	 * are deleted from the cache. backref nodes for upper level
1101	 * tree blocks are left in the cache to avoid unnecessary backref
1102	 * lookup.
1103	 */
1104	while (!list_empty(&useless)) {
1105		upper = list_entry(useless.next, struct backref_node, list);
1106		list_del_init(&upper->list);
1107		ASSERT(list_empty(&upper->upper));
1108		if (upper == node)
1109			node = NULL;
1110		if (upper->lowest) {
1111			list_del_init(&upper->lower);
1112			upper->lowest = 0;
1113		}
1114		while (!list_empty(&upper->lower)) {
1115			edge = list_entry(upper->lower.next,
1116					  struct backref_edge, list[UPPER]);
1117			list_del(&edge->list[UPPER]);
1118			list_del(&edge->list[LOWER]);
1119			lower = edge->node[LOWER];
1120			free_backref_edge(cache, edge);
1121
1122			if (list_empty(&lower->upper))
1123				list_add(&lower->list, &useless);
1124		}
1125		__mark_block_processed(rc, upper);
1126		if (upper->level > 0) {
1127			list_add(&upper->list, &cache->detached);
1128			upper->detached = 1;
1129		} else {
1130			rb_erase(&upper->rb_node, &cache->rb_root);
1131			free_backref_node(cache, upper);
1132		}
1133	}
1134out:
1135	btrfs_free_path(path1);
1136	btrfs_free_path(path2);
1137	if (err) {
1138		while (!list_empty(&useless)) {
1139			lower = list_entry(useless.next,
1140					   struct backref_node, list);
1141			list_del_init(&lower->list);
1142		}
1143		while (!list_empty(&list)) {
1144			edge = list_first_entry(&list, struct backref_edge,
1145						list[UPPER]);
1146			list_del(&edge->list[UPPER]);
 
 
 
 
 
 
 
 
 
1147			list_del(&edge->list[LOWER]);
1148			lower = edge->node[LOWER];
1149			upper = edge->node[UPPER];
1150			free_backref_edge(cache, edge);
1151
1152			/*
1153			 * Lower is no longer linked to any upper backref nodes
1154			 * and isn't in the cache, we can free it ourselves.
1155			 */
1156			if (list_empty(&lower->upper) &&
1157			    RB_EMPTY_NODE(&lower->rb_node))
1158				list_add(&lower->list, &useless);
1159
1160			if (!RB_EMPTY_NODE(&upper->rb_node))
1161				continue;
1162
1163			/* Add this guy's upper edges to the list to proces */
1164			list_for_each_entry(edge, &upper->upper, list[LOWER])
1165				list_add_tail(&edge->list[UPPER], &list);
1166			if (list_empty(&upper->upper))
1167				list_add(&upper->list, &useless);
1168		}
1169
1170		while (!list_empty(&useless)) {
1171			lower = list_entry(useless.next,
1172					   struct backref_node, list);
1173			list_del_init(&lower->list);
1174			free_backref_node(cache, lower);
1175		}
1176		return ERR_PTR(err);
1177	}
1178	ASSERT(!node || !node->detached);
1179	return node;
1180}
1181
1182/*
1183 * helper to add backref node for the newly created snapshot.
1184 * the backref node is created by cloning backref node that
1185 * corresponds to root of source tree
1186 */
1187static int clone_backref_node(struct btrfs_trans_handle *trans,
1188			      struct reloc_control *rc,
1189			      struct btrfs_root *src,
1190			      struct btrfs_root *dest)
1191{
1192	struct btrfs_root *reloc_root = src->reloc_root;
1193	struct backref_cache *cache = &rc->backref_cache;
1194	struct backref_node *node = NULL;
1195	struct backref_node *new_node;
1196	struct backref_edge *edge;
1197	struct backref_edge *new_edge;
1198	struct rb_node *rb_node;
1199
1200	if (cache->last_trans > 0)
1201		update_backref_cache(trans, cache);
1202
1203	rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1204	if (rb_node) {
1205		node = rb_entry(rb_node, struct backref_node, rb_node);
1206		if (node->detached)
1207			node = NULL;
1208		else
1209			BUG_ON(node->new_bytenr != reloc_root->node->start);
1210	}
1211
1212	if (!node) {
1213		rb_node = tree_search(&cache->rb_root,
1214				      reloc_root->commit_root->start);
1215		if (rb_node) {
1216			node = rb_entry(rb_node, struct backref_node,
1217					rb_node);
1218			BUG_ON(node->detached);
1219		}
1220	}
1221
1222	if (!node)
1223		return 0;
1224
1225	new_node = alloc_backref_node(cache);
1226	if (!new_node)
1227		return -ENOMEM;
1228
1229	new_node->bytenr = dest->node->start;
1230	new_node->level = node->level;
1231	new_node->lowest = node->lowest;
1232	new_node->checked = 1;
1233	new_node->root = dest;
1234
1235	if (!node->lowest) {
1236		list_for_each_entry(edge, &node->lower, list[UPPER]) {
1237			new_edge = alloc_backref_edge(cache);
1238			if (!new_edge)
1239				goto fail;
1240
1241			new_edge->node[UPPER] = new_node;
1242			new_edge->node[LOWER] = edge->node[LOWER];
1243			list_add_tail(&new_edge->list[UPPER],
1244				      &new_node->lower);
1245		}
1246	} else {
1247		list_add_tail(&new_node->lower, &cache->leaves);
1248	}
1249
1250	rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1251			      &new_node->rb_node);
1252	if (rb_node)
1253		backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1254
1255	if (!new_node->lowest) {
1256		list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1257			list_add_tail(&new_edge->list[LOWER],
1258				      &new_edge->node[LOWER]->upper);
1259		}
1260	}
1261	return 0;
1262fail:
1263	while (!list_empty(&new_node->lower)) {
1264		new_edge = list_entry(new_node->lower.next,
1265				      struct backref_edge, list[UPPER]);
1266		list_del(&new_edge->list[UPPER]);
1267		free_backref_edge(cache, new_edge);
1268	}
1269	free_backref_node(cache, new_node);
1270	return -ENOMEM;
1271}
1272
1273/*
1274 * helper to add 'address of tree root -> reloc tree' mapping
1275 */
1276static int __must_check __add_reloc_root(struct btrfs_root *root)
1277{
1278	struct rb_node *rb_node;
1279	struct mapping_node *node;
1280	struct reloc_control *rc = root->fs_info->reloc_ctl;
1281
1282	node = kmalloc(sizeof(*node), GFP_NOFS);
1283	if (!node)
1284		return -ENOMEM;
1285
1286	node->bytenr = root->node->start;
1287	node->data = root;
1288
1289	spin_lock(&rc->reloc_root_tree.lock);
1290	rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1291			      node->bytenr, &node->rb_node);
1292	spin_unlock(&rc->reloc_root_tree.lock);
1293	if (rb_node) {
1294		btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
1295			    "for start=%llu while inserting into relocation "
1296			    "tree", node->bytenr);
1297		kfree(node);
1298		return -EEXIST;
1299	}
1300
1301	list_add_tail(&root->root_list, &rc->reloc_roots);
1302	return 0;
1303}
1304
1305/*
1306 * helper to delete the 'address of tree root -> reloc tree'
1307 * mapping
1308 */
1309static void __del_reloc_root(struct btrfs_root *root)
1310{
1311	struct rb_node *rb_node;
1312	struct mapping_node *node = NULL;
1313	struct reloc_control *rc = root->fs_info->reloc_ctl;
1314
1315	spin_lock(&rc->reloc_root_tree.lock);
1316	rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1317			      root->node->start);
1318	if (rb_node) {
1319		node = rb_entry(rb_node, struct mapping_node, rb_node);
1320		rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1321	}
1322	spin_unlock(&rc->reloc_root_tree.lock);
1323
1324	if (!node)
1325		return;
1326	BUG_ON((struct btrfs_root *)node->data != root);
1327
1328	spin_lock(&root->fs_info->trans_lock);
1329	list_del_init(&root->root_list);
1330	spin_unlock(&root->fs_info->trans_lock);
1331	kfree(node);
1332}
1333
1334/*
1335 * helper to update the 'address of tree root -> reloc tree'
1336 * mapping
1337 */
1338static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1339{
1340	struct rb_node *rb_node;
1341	struct mapping_node *node = NULL;
1342	struct reloc_control *rc = root->fs_info->reloc_ctl;
1343
1344	spin_lock(&rc->reloc_root_tree.lock);
1345	rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1346			      root->node->start);
1347	if (rb_node) {
1348		node = rb_entry(rb_node, struct mapping_node, rb_node);
1349		rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1350	}
1351	spin_unlock(&rc->reloc_root_tree.lock);
1352
1353	if (!node)
1354		return 0;
1355	BUG_ON((struct btrfs_root *)node->data != root);
1356
1357	spin_lock(&rc->reloc_root_tree.lock);
1358	node->bytenr = new_bytenr;
1359	rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1360			      node->bytenr, &node->rb_node);
1361	spin_unlock(&rc->reloc_root_tree.lock);
1362	if (rb_node)
1363		backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1364	return 0;
1365}
1366
1367static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1368					struct btrfs_root *root, u64 objectid)
1369{
1370	struct btrfs_root *reloc_root;
1371	struct extent_buffer *eb;
1372	struct btrfs_root_item *root_item;
1373	struct btrfs_key root_key;
1374	u64 last_snap = 0;
1375	int ret;
1376
1377	root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1378	BUG_ON(!root_item);
1379
1380	root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1381	root_key.type = BTRFS_ROOT_ITEM_KEY;
1382	root_key.offset = objectid;
1383
1384	if (root->root_key.objectid == objectid) {
1385		/* called by btrfs_init_reloc_root */
1386		ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1387				      BTRFS_TREE_RELOC_OBJECTID);
1388		BUG_ON(ret);
1389
1390		last_snap = btrfs_root_last_snapshot(&root->root_item);
1391		btrfs_set_root_last_snapshot(&root->root_item,
1392					     trans->transid - 1);
1393	} else {
1394		/*
1395		 * called by btrfs_reloc_post_snapshot_hook.
1396		 * the source tree is a reloc tree, all tree blocks
1397		 * modified after it was created have RELOC flag
1398		 * set in their headers. so it's OK to not update
1399		 * the 'last_snapshot'.
1400		 */
1401		ret = btrfs_copy_root(trans, root, root->node, &eb,
1402				      BTRFS_TREE_RELOC_OBJECTID);
1403		BUG_ON(ret);
1404	}
1405
1406	memcpy(root_item, &root->root_item, sizeof(*root_item));
1407	btrfs_set_root_bytenr(root_item, eb->start);
1408	btrfs_set_root_level(root_item, btrfs_header_level(eb));
1409	btrfs_set_root_generation(root_item, trans->transid);
1410
1411	if (root->root_key.objectid == objectid) {
1412		btrfs_set_root_refs(root_item, 0);
1413		memset(&root_item->drop_progress, 0,
1414		       sizeof(struct btrfs_disk_key));
1415		root_item->drop_level = 0;
1416		/*
1417		 * abuse rtransid, it is safe because it is impossible to
1418		 * receive data into a relocation tree.
1419		 */
1420		btrfs_set_root_rtransid(root_item, last_snap);
1421		btrfs_set_root_otransid(root_item, trans->transid);
1422	}
1423
1424	btrfs_tree_unlock(eb);
1425	free_extent_buffer(eb);
1426
1427	ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1428				&root_key, root_item);
1429	BUG_ON(ret);
1430	kfree(root_item);
1431
1432	reloc_root = btrfs_read_fs_root(root->fs_info->tree_root, &root_key);
 
1433	BUG_ON(IS_ERR(reloc_root));
1434	reloc_root->last_trans = trans->transid;
1435	return reloc_root;
1436}
1437
1438/*
1439 * create reloc tree for a given fs tree. reloc tree is just a
1440 * snapshot of the fs tree with special root objectid.
1441 */
1442int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1443			  struct btrfs_root *root)
1444{
1445	struct btrfs_root *reloc_root;
1446	struct reloc_control *rc = root->fs_info->reloc_ctl;
1447	struct btrfs_block_rsv *rsv;
1448	int clear_rsv = 0;
1449	int ret;
1450
1451	if (root->reloc_root) {
1452		reloc_root = root->reloc_root;
1453		reloc_root->last_trans = trans->transid;
1454		return 0;
1455	}
1456
1457	if (!rc || !rc->create_reloc_tree ||
1458	    root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1459		return 0;
1460
1461	if (!trans->reloc_reserved) {
1462		rsv = trans->block_rsv;
1463		trans->block_rsv = rc->block_rsv;
1464		clear_rsv = 1;
1465	}
1466	reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1467	if (clear_rsv)
1468		trans->block_rsv = rsv;
1469
1470	ret = __add_reloc_root(reloc_root);
1471	BUG_ON(ret < 0);
1472	root->reloc_root = reloc_root;
1473	return 0;
1474}
1475
1476/*
1477 * update root item of reloc tree
1478 */
1479int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1480			    struct btrfs_root *root)
1481{
1482	struct btrfs_root *reloc_root;
1483	struct btrfs_root_item *root_item;
 
1484	int ret;
1485
1486	if (!root->reloc_root)
1487		goto out;
1488
1489	reloc_root = root->reloc_root;
1490	root_item = &reloc_root->root_item;
1491
1492	if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1493	    btrfs_root_refs(root_item) == 0) {
1494		root->reloc_root = NULL;
1495		__del_reloc_root(reloc_root);
1496	}
1497
 
 
1498	if (reloc_root->commit_root != reloc_root->node) {
1499		btrfs_set_root_node(root_item, reloc_root->node);
1500		free_extent_buffer(reloc_root->commit_root);
1501		reloc_root->commit_root = btrfs_root_node(reloc_root);
1502	}
1503
1504	ret = btrfs_update_root(trans, root->fs_info->tree_root,
1505				&reloc_root->root_key, root_item);
1506	BUG_ON(ret);
1507
1508out:
1509	return 0;
1510}
1511
1512/*
1513 * helper to find first cached inode with inode number >= objectid
1514 * in a subvolume
1515 */
1516static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1517{
1518	struct rb_node *node;
1519	struct rb_node *prev;
1520	struct btrfs_inode *entry;
1521	struct inode *inode;
1522
1523	spin_lock(&root->inode_lock);
1524again:
1525	node = root->inode_tree.rb_node;
1526	prev = NULL;
1527	while (node) {
1528		prev = node;
1529		entry = rb_entry(node, struct btrfs_inode, rb_node);
1530
1531		if (objectid < btrfs_ino(&entry->vfs_inode))
1532			node = node->rb_left;
1533		else if (objectid > btrfs_ino(&entry->vfs_inode))
1534			node = node->rb_right;
1535		else
1536			break;
1537	}
1538	if (!node) {
1539		while (prev) {
1540			entry = rb_entry(prev, struct btrfs_inode, rb_node);
1541			if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1542				node = prev;
1543				break;
1544			}
1545			prev = rb_next(prev);
1546		}
1547	}
1548	while (node) {
1549		entry = rb_entry(node, struct btrfs_inode, rb_node);
1550		inode = igrab(&entry->vfs_inode);
1551		if (inode) {
1552			spin_unlock(&root->inode_lock);
1553			return inode;
1554		}
1555
1556		objectid = btrfs_ino(&entry->vfs_inode) + 1;
1557		if (cond_resched_lock(&root->inode_lock))
1558			goto again;
1559
1560		node = rb_next(node);
1561	}
1562	spin_unlock(&root->inode_lock);
1563	return NULL;
1564}
1565
1566static int in_block_group(u64 bytenr,
1567			  struct btrfs_block_group_cache *block_group)
1568{
1569	if (bytenr >= block_group->key.objectid &&
1570	    bytenr < block_group->key.objectid + block_group->key.offset)
1571		return 1;
1572	return 0;
1573}
1574
1575/*
1576 * get new location of data
1577 */
1578static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1579			    u64 bytenr, u64 num_bytes)
1580{
1581	struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1582	struct btrfs_path *path;
1583	struct btrfs_file_extent_item *fi;
1584	struct extent_buffer *leaf;
1585	int ret;
1586
1587	path = btrfs_alloc_path();
1588	if (!path)
1589		return -ENOMEM;
1590
1591	bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1592	ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1593				       bytenr, 0);
1594	if (ret < 0)
1595		goto out;
1596	if (ret > 0) {
1597		ret = -ENOENT;
1598		goto out;
1599	}
1600
1601	leaf = path->nodes[0];
1602	fi = btrfs_item_ptr(leaf, path->slots[0],
1603			    struct btrfs_file_extent_item);
1604
1605	BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1606	       btrfs_file_extent_compression(leaf, fi) ||
1607	       btrfs_file_extent_encryption(leaf, fi) ||
1608	       btrfs_file_extent_other_encoding(leaf, fi));
1609
1610	if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1611		ret = -EINVAL;
1612		goto out;
1613	}
1614
1615	*new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1616	ret = 0;
1617out:
1618	btrfs_free_path(path);
1619	return ret;
1620}
1621
1622/*
1623 * update file extent items in the tree leaf to point to
1624 * the new locations.
1625 */
1626static noinline_for_stack
1627int replace_file_extents(struct btrfs_trans_handle *trans,
1628			 struct reloc_control *rc,
1629			 struct btrfs_root *root,
1630			 struct extent_buffer *leaf)
1631{
1632	struct btrfs_key key;
1633	struct btrfs_file_extent_item *fi;
1634	struct inode *inode = NULL;
1635	u64 parent;
1636	u64 bytenr;
1637	u64 new_bytenr = 0;
1638	u64 num_bytes;
1639	u64 end;
1640	u32 nritems;
1641	u32 i;
1642	int ret = 0;
1643	int first = 1;
1644	int dirty = 0;
1645
1646	if (rc->stage != UPDATE_DATA_PTRS)
1647		return 0;
1648
1649	/* reloc trees always use full backref */
1650	if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1651		parent = leaf->start;
1652	else
1653		parent = 0;
1654
1655	nritems = btrfs_header_nritems(leaf);
1656	for (i = 0; i < nritems; i++) {
1657		cond_resched();
1658		btrfs_item_key_to_cpu(leaf, &key, i);
1659		if (key.type != BTRFS_EXTENT_DATA_KEY)
1660			continue;
1661		fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1662		if (btrfs_file_extent_type(leaf, fi) ==
1663		    BTRFS_FILE_EXTENT_INLINE)
1664			continue;
1665		bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1666		num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1667		if (bytenr == 0)
1668			continue;
1669		if (!in_block_group(bytenr, rc->block_group))
1670			continue;
1671
1672		/*
1673		 * if we are modifying block in fs tree, wait for readpage
1674		 * to complete and drop the extent cache
1675		 */
1676		if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1677			if (first) {
1678				inode = find_next_inode(root, key.objectid);
1679				first = 0;
1680			} else if (inode && btrfs_ino(inode) < key.objectid) {
1681				btrfs_add_delayed_iput(inode);
1682				inode = find_next_inode(root, key.objectid);
1683			}
1684			if (inode && btrfs_ino(inode) == key.objectid) {
1685				end = key.offset +
1686				      btrfs_file_extent_num_bytes(leaf, fi);
1687				WARN_ON(!IS_ALIGNED(key.offset,
1688						    root->sectorsize));
1689				WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1690				end--;
1691				ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1692						      key.offset, end);
 
1693				if (!ret)
1694					continue;
1695
1696				btrfs_drop_extent_cache(inode, key.offset, end,
1697							1);
1698				unlock_extent(&BTRFS_I(inode)->io_tree,
1699					      key.offset, end);
1700			}
1701		}
1702
1703		ret = get_new_location(rc->data_inode, &new_bytenr,
1704				       bytenr, num_bytes);
1705		if (ret) {
1706			/*
1707			 * Don't have to abort since we've not changed anything
1708			 * in the file extent yet.
1709			 */
1710			break;
1711		}
 
1712
1713		btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1714		dirty = 1;
1715
1716		key.offset -= btrfs_file_extent_offset(leaf, fi);
1717		ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1718					   num_bytes, parent,
1719					   btrfs_header_owner(leaf),
1720					   key.objectid, key.offset);
1721		if (ret) {
1722			btrfs_abort_transaction(trans, root, ret);
1723			break;
1724		}
1725
1726		ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1727					parent, btrfs_header_owner(leaf),
1728					key.objectid, key.offset);
1729		if (ret) {
1730			btrfs_abort_transaction(trans, root, ret);
1731			break;
1732		}
1733	}
1734	if (dirty)
1735		btrfs_mark_buffer_dirty(leaf);
1736	if (inode)
1737		btrfs_add_delayed_iput(inode);
1738	return ret;
1739}
1740
1741static noinline_for_stack
1742int memcmp_node_keys(struct extent_buffer *eb, int slot,
1743		     struct btrfs_path *path, int level)
1744{
1745	struct btrfs_disk_key key1;
1746	struct btrfs_disk_key key2;
1747	btrfs_node_key(eb, &key1, slot);
1748	btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1749	return memcmp(&key1, &key2, sizeof(key1));
1750}
1751
1752/*
1753 * try to replace tree blocks in fs tree with the new blocks
1754 * in reloc tree. tree blocks haven't been modified since the
1755 * reloc tree was create can be replaced.
1756 *
1757 * if a block was replaced, level of the block + 1 is returned.
1758 * if no block got replaced, 0 is returned. if there are other
1759 * errors, a negative error number is returned.
1760 */
1761static noinline_for_stack
1762int replace_path(struct btrfs_trans_handle *trans,
1763		 struct btrfs_root *dest, struct btrfs_root *src,
1764		 struct btrfs_path *path, struct btrfs_key *next_key,
1765		 int lowest_level, int max_level)
1766{
1767	struct extent_buffer *eb;
1768	struct extent_buffer *parent;
1769	struct btrfs_key key;
1770	u64 old_bytenr;
1771	u64 new_bytenr;
1772	u64 old_ptr_gen;
1773	u64 new_ptr_gen;
1774	u64 last_snapshot;
1775	u32 blocksize;
1776	int cow = 0;
1777	int level;
1778	int ret;
1779	int slot;
1780
1781	BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1782	BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1783
1784	last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1785again:
1786	slot = path->slots[lowest_level];
1787	btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1788
1789	eb = btrfs_lock_root_node(dest);
1790	btrfs_set_lock_blocking(eb);
1791	level = btrfs_header_level(eb);
1792
1793	if (level < lowest_level) {
1794		btrfs_tree_unlock(eb);
1795		free_extent_buffer(eb);
1796		return 0;
1797	}
1798
1799	if (cow) {
1800		ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1801		BUG_ON(ret);
1802	}
1803	btrfs_set_lock_blocking(eb);
1804
1805	if (next_key) {
1806		next_key->objectid = (u64)-1;
1807		next_key->type = (u8)-1;
1808		next_key->offset = (u64)-1;
1809	}
1810
1811	parent = eb;
1812	while (1) {
1813		level = btrfs_header_level(parent);
1814		BUG_ON(level < lowest_level);
1815
1816		ret = btrfs_bin_search(parent, &key, level, &slot);
1817		if (ret && slot > 0)
1818			slot--;
1819
1820		if (next_key && slot + 1 < btrfs_header_nritems(parent))
1821			btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1822
1823		old_bytenr = btrfs_node_blockptr(parent, slot);
1824		blocksize = dest->nodesize;
1825		old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1826
1827		if (level <= max_level) {
1828			eb = path->nodes[level];
1829			new_bytenr = btrfs_node_blockptr(eb,
1830							path->slots[level]);
1831			new_ptr_gen = btrfs_node_ptr_generation(eb,
1832							path->slots[level]);
1833		} else {
1834			new_bytenr = 0;
1835			new_ptr_gen = 0;
1836		}
1837
1838		if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
 
1839			ret = level;
1840			break;
1841		}
1842
1843		if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1844		    memcmp_node_keys(parent, slot, path, level)) {
1845			if (level <= lowest_level) {
1846				ret = 0;
1847				break;
1848			}
1849
1850			eb = read_tree_block(dest, old_bytenr, old_ptr_gen);
1851			if (IS_ERR(eb)) {
1852				ret = PTR_ERR(eb);
1853				break;
1854			} else if (!extent_buffer_uptodate(eb)) {
1855				ret = -EIO;
1856				free_extent_buffer(eb);
1857				break;
1858			}
1859			btrfs_tree_lock(eb);
1860			if (cow) {
1861				ret = btrfs_cow_block(trans, dest, eb, parent,
1862						      slot, &eb);
1863				BUG_ON(ret);
1864			}
1865			btrfs_set_lock_blocking(eb);
1866
1867			btrfs_tree_unlock(parent);
1868			free_extent_buffer(parent);
1869
1870			parent = eb;
1871			continue;
1872		}
1873
1874		if (!cow) {
1875			btrfs_tree_unlock(parent);
1876			free_extent_buffer(parent);
1877			cow = 1;
1878			goto again;
1879		}
1880
1881		btrfs_node_key_to_cpu(path->nodes[level], &key,
1882				      path->slots[level]);
1883		btrfs_release_path(path);
1884
1885		path->lowest_level = level;
1886		ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1887		path->lowest_level = 0;
1888		BUG_ON(ret);
1889
1890		/*
1891		 * swap blocks in fs tree and reloc tree.
1892		 */
1893		btrfs_set_node_blockptr(parent, slot, new_bytenr);
1894		btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1895		btrfs_mark_buffer_dirty(parent);
1896
1897		btrfs_set_node_blockptr(path->nodes[level],
1898					path->slots[level], old_bytenr);
1899		btrfs_set_node_ptr_generation(path->nodes[level],
1900					      path->slots[level], old_ptr_gen);
1901		btrfs_mark_buffer_dirty(path->nodes[level]);
1902
1903		ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1904					path->nodes[level]->start,
1905					src->root_key.objectid, level - 1, 0);
1906		BUG_ON(ret);
1907		ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1908					0, dest->root_key.objectid, level - 1,
1909					0);
1910		BUG_ON(ret);
1911
1912		ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1913					path->nodes[level]->start,
1914					src->root_key.objectid, level - 1, 0);
1915		BUG_ON(ret);
1916
1917		ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1918					0, dest->root_key.objectid, level - 1,
1919					0);
1920		BUG_ON(ret);
1921
1922		btrfs_unlock_up_safe(path, 0);
1923
1924		ret = level;
1925		break;
1926	}
1927	btrfs_tree_unlock(parent);
1928	free_extent_buffer(parent);
1929	return ret;
1930}
1931
1932/*
1933 * helper to find next relocated block in reloc tree
1934 */
1935static noinline_for_stack
1936int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1937		       int *level)
1938{
1939	struct extent_buffer *eb;
1940	int i;
1941	u64 last_snapshot;
1942	u32 nritems;
1943
1944	last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1945
1946	for (i = 0; i < *level; i++) {
1947		free_extent_buffer(path->nodes[i]);
1948		path->nodes[i] = NULL;
1949	}
1950
1951	for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1952		eb = path->nodes[i];
1953		nritems = btrfs_header_nritems(eb);
1954		while (path->slots[i] + 1 < nritems) {
1955			path->slots[i]++;
1956			if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1957			    last_snapshot)
1958				continue;
1959
1960			*level = i;
1961			return 0;
1962		}
1963		free_extent_buffer(path->nodes[i]);
1964		path->nodes[i] = NULL;
1965	}
1966	return 1;
1967}
1968
1969/*
1970 * walk down reloc tree to find relocated block of lowest level
1971 */
1972static noinline_for_stack
1973int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1974			 int *level)
1975{
1976	struct extent_buffer *eb = NULL;
1977	int i;
1978	u64 bytenr;
1979	u64 ptr_gen = 0;
1980	u64 last_snapshot;
 
1981	u32 nritems;
1982
1983	last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1984
1985	for (i = *level; i > 0; i--) {
1986		eb = path->nodes[i];
1987		nritems = btrfs_header_nritems(eb);
1988		while (path->slots[i] < nritems) {
1989			ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1990			if (ptr_gen > last_snapshot)
1991				break;
1992			path->slots[i]++;
1993		}
1994		if (path->slots[i] >= nritems) {
1995			if (i == *level)
1996				break;
1997			*level = i + 1;
1998			return 0;
1999		}
2000		if (i == 1) {
2001			*level = i;
2002			return 0;
2003		}
2004
2005		bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2006		eb = read_tree_block(root, bytenr, ptr_gen);
2007		if (IS_ERR(eb)) {
2008			return PTR_ERR(eb);
2009		} else if (!extent_buffer_uptodate(eb)) {
2010			free_extent_buffer(eb);
2011			return -EIO;
2012		}
2013		BUG_ON(btrfs_header_level(eb) != i - 1);
2014		path->nodes[i - 1] = eb;
2015		path->slots[i - 1] = 0;
2016	}
2017	return 1;
2018}
2019
2020/*
2021 * invalidate extent cache for file extents whose key in range of
2022 * [min_key, max_key)
2023 */
2024static int invalidate_extent_cache(struct btrfs_root *root,
2025				   struct btrfs_key *min_key,
2026				   struct btrfs_key *max_key)
2027{
2028	struct inode *inode = NULL;
2029	u64 objectid;
2030	u64 start, end;
2031	u64 ino;
2032
2033	objectid = min_key->objectid;
2034	while (1) {
2035		cond_resched();
2036		iput(inode);
2037
2038		if (objectid > max_key->objectid)
2039			break;
2040
2041		inode = find_next_inode(root, objectid);
2042		if (!inode)
2043			break;
2044		ino = btrfs_ino(inode);
2045
2046		if (ino > max_key->objectid) {
2047			iput(inode);
2048			break;
2049		}
2050
2051		objectid = ino + 1;
2052		if (!S_ISREG(inode->i_mode))
2053			continue;
2054
2055		if (unlikely(min_key->objectid == ino)) {
2056			if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2057				continue;
2058			if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2059				start = 0;
2060			else {
2061				start = min_key->offset;
2062				WARN_ON(!IS_ALIGNED(start, root->sectorsize));
2063			}
2064		} else {
2065			start = 0;
2066		}
2067
2068		if (unlikely(max_key->objectid == ino)) {
2069			if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2070				continue;
2071			if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2072				end = (u64)-1;
2073			} else {
2074				if (max_key->offset == 0)
2075					continue;
2076				end = max_key->offset;
2077				WARN_ON(!IS_ALIGNED(end, root->sectorsize));
2078				end--;
2079			}
2080		} else {
2081			end = (u64)-1;
2082		}
2083
2084		/* the lock_extent waits for readpage to complete */
2085		lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2086		btrfs_drop_extent_cache(inode, start, end, 1);
2087		unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2088	}
2089	return 0;
2090}
2091
2092static int find_next_key(struct btrfs_path *path, int level,
2093			 struct btrfs_key *key)
2094
2095{
2096	while (level < BTRFS_MAX_LEVEL) {
2097		if (!path->nodes[level])
2098			break;
2099		if (path->slots[level] + 1 <
2100		    btrfs_header_nritems(path->nodes[level])) {
2101			btrfs_node_key_to_cpu(path->nodes[level], key,
2102					      path->slots[level] + 1);
2103			return 0;
2104		}
2105		level++;
2106	}
2107	return 1;
2108}
2109
2110/*
2111 * merge the relocated tree blocks in reloc tree with corresponding
2112 * fs tree.
2113 */
2114static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2115					       struct btrfs_root *root)
2116{
2117	LIST_HEAD(inode_list);
2118	struct btrfs_key key;
2119	struct btrfs_key next_key;
2120	struct btrfs_trans_handle *trans = NULL;
2121	struct btrfs_root *reloc_root;
2122	struct btrfs_root_item *root_item;
2123	struct btrfs_path *path;
2124	struct extent_buffer *leaf;
 
2125	int level;
2126	int max_level;
2127	int replaced = 0;
2128	int ret;
2129	int err = 0;
2130	u32 min_reserved;
2131
2132	path = btrfs_alloc_path();
2133	if (!path)
2134		return -ENOMEM;
2135	path->reada = READA_FORWARD;
2136
2137	reloc_root = root->reloc_root;
2138	root_item = &reloc_root->root_item;
2139
2140	if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2141		level = btrfs_root_level(root_item);
2142		extent_buffer_get(reloc_root->node);
2143		path->nodes[level] = reloc_root->node;
2144		path->slots[level] = 0;
2145	} else {
2146		btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2147
2148		level = root_item->drop_level;
2149		BUG_ON(level == 0);
2150		path->lowest_level = level;
2151		ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2152		path->lowest_level = 0;
2153		if (ret < 0) {
2154			btrfs_free_path(path);
2155			return ret;
2156		}
2157
2158		btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2159				      path->slots[level]);
2160		WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2161
2162		btrfs_unlock_up_safe(path, 0);
2163	}
2164
2165	min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2166	memset(&next_key, 0, sizeof(next_key));
2167
2168	while (1) {
2169		ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2170					     BTRFS_RESERVE_FLUSH_ALL);
2171		if (ret) {
2172			err = ret;
2173			goto out;
2174		}
2175		trans = btrfs_start_transaction(root, 0);
2176		if (IS_ERR(trans)) {
2177			err = PTR_ERR(trans);
2178			trans = NULL;
2179			goto out;
2180		}
2181		trans->block_rsv = rc->block_rsv;
2182
 
 
 
 
 
 
 
 
 
2183		replaced = 0;
2184		max_level = level;
2185
2186		ret = walk_down_reloc_tree(reloc_root, path, &level);
2187		if (ret < 0) {
2188			err = ret;
2189			goto out;
2190		}
2191		if (ret > 0)
2192			break;
2193
2194		if (!find_next_key(path, level, &key) &&
2195		    btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2196			ret = 0;
2197		} else {
2198			ret = replace_path(trans, root, reloc_root, path,
2199					   &next_key, level, max_level);
2200		}
2201		if (ret < 0) {
2202			err = ret;
2203			goto out;
2204		}
2205
2206		if (ret > 0) {
2207			level = ret;
2208			btrfs_node_key_to_cpu(path->nodes[level], &key,
2209					      path->slots[level]);
2210			replaced = 1;
2211		}
2212
2213		ret = walk_up_reloc_tree(reloc_root, path, &level);
2214		if (ret > 0)
2215			break;
2216
2217		BUG_ON(level == 0);
2218		/*
2219		 * save the merging progress in the drop_progress.
2220		 * this is OK since root refs == 1 in this case.
2221		 */
2222		btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2223			       path->slots[level]);
2224		root_item->drop_level = level;
2225
 
2226		btrfs_end_transaction_throttle(trans, root);
2227		trans = NULL;
2228
2229		btrfs_btree_balance_dirty(root);
2230
2231		if (replaced && rc->stage == UPDATE_DATA_PTRS)
2232			invalidate_extent_cache(root, &key, &next_key);
2233	}
2234
2235	/*
2236	 * handle the case only one block in the fs tree need to be
2237	 * relocated and the block is tree root.
2238	 */
2239	leaf = btrfs_lock_root_node(root);
2240	ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2241	btrfs_tree_unlock(leaf);
2242	free_extent_buffer(leaf);
2243	if (ret < 0)
2244		err = ret;
2245out:
2246	btrfs_free_path(path);
2247
2248	if (err == 0) {
2249		memset(&root_item->drop_progress, 0,
2250		       sizeof(root_item->drop_progress));
2251		root_item->drop_level = 0;
2252		btrfs_set_root_refs(root_item, 0);
2253		btrfs_update_reloc_root(trans, root);
2254	}
2255
2256	if (trans)
2257		btrfs_end_transaction_throttle(trans, root);
2258
2259	btrfs_btree_balance_dirty(root);
2260
2261	if (replaced && rc->stage == UPDATE_DATA_PTRS)
2262		invalidate_extent_cache(root, &key, &next_key);
2263
2264	return err;
2265}
2266
2267static noinline_for_stack
2268int prepare_to_merge(struct reloc_control *rc, int err)
2269{
2270	struct btrfs_root *root = rc->extent_root;
2271	struct btrfs_root *reloc_root;
2272	struct btrfs_trans_handle *trans;
2273	LIST_HEAD(reloc_roots);
2274	u64 num_bytes = 0;
2275	int ret;
2276
2277	mutex_lock(&root->fs_info->reloc_mutex);
2278	rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2279	rc->merging_rsv_size += rc->nodes_relocated * 2;
2280	mutex_unlock(&root->fs_info->reloc_mutex);
2281
2282again:
2283	if (!err) {
2284		num_bytes = rc->merging_rsv_size;
2285		ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2286					  BTRFS_RESERVE_FLUSH_ALL);
2287		if (ret)
2288			err = ret;
2289	}
2290
2291	trans = btrfs_join_transaction(rc->extent_root);
2292	if (IS_ERR(trans)) {
2293		if (!err)
2294			btrfs_block_rsv_release(rc->extent_root,
2295						rc->block_rsv, num_bytes);
2296		return PTR_ERR(trans);
2297	}
2298
2299	if (!err) {
2300		if (num_bytes != rc->merging_rsv_size) {
2301			btrfs_end_transaction(trans, rc->extent_root);
2302			btrfs_block_rsv_release(rc->extent_root,
2303						rc->block_rsv, num_bytes);
2304			goto again;
2305		}
2306	}
2307
2308	rc->merge_reloc_tree = 1;
2309
2310	while (!list_empty(&rc->reloc_roots)) {
2311		reloc_root = list_entry(rc->reloc_roots.next,
2312					struct btrfs_root, root_list);
2313		list_del_init(&reloc_root->root_list);
2314
2315		root = read_fs_root(reloc_root->fs_info,
2316				    reloc_root->root_key.offset);
2317		BUG_ON(IS_ERR(root));
2318		BUG_ON(root->reloc_root != reloc_root);
2319
2320		/*
2321		 * set reference count to 1, so btrfs_recover_relocation
2322		 * knows it should resumes merging
2323		 */
2324		if (!err)
2325			btrfs_set_root_refs(&reloc_root->root_item, 1);
2326		btrfs_update_reloc_root(trans, root);
2327
2328		list_add(&reloc_root->root_list, &reloc_roots);
2329	}
2330
2331	list_splice(&reloc_roots, &rc->reloc_roots);
2332
2333	if (!err)
2334		btrfs_commit_transaction(trans, rc->extent_root);
2335	else
2336		btrfs_end_transaction(trans, rc->extent_root);
2337	return err;
2338}
2339
2340static noinline_for_stack
2341void free_reloc_roots(struct list_head *list)
2342{
2343	struct btrfs_root *reloc_root;
2344
2345	while (!list_empty(list)) {
2346		reloc_root = list_entry(list->next, struct btrfs_root,
2347					root_list);
2348		__del_reloc_root(reloc_root);
2349	}
2350}
2351
2352static noinline_for_stack
2353void merge_reloc_roots(struct reloc_control *rc)
2354{
2355	struct btrfs_root *root;
2356	struct btrfs_root *reloc_root;
2357	u64 last_snap;
2358	u64 otransid;
2359	u64 objectid;
2360	LIST_HEAD(reloc_roots);
2361	int found = 0;
2362	int ret = 0;
2363again:
2364	root = rc->extent_root;
2365
2366	/*
2367	 * this serializes us with btrfs_record_root_in_transaction,
2368	 * we have to make sure nobody is in the middle of
2369	 * adding their roots to the list while we are
2370	 * doing this splice
2371	 */
2372	mutex_lock(&root->fs_info->reloc_mutex);
2373	list_splice_init(&rc->reloc_roots, &reloc_roots);
2374	mutex_unlock(&root->fs_info->reloc_mutex);
2375
2376	while (!list_empty(&reloc_roots)) {
2377		found = 1;
2378		reloc_root = list_entry(reloc_roots.next,
2379					struct btrfs_root, root_list);
2380
2381		if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2382			root = read_fs_root(reloc_root->fs_info,
2383					    reloc_root->root_key.offset);
2384			BUG_ON(IS_ERR(root));
2385			BUG_ON(root->reloc_root != reloc_root);
2386
2387			ret = merge_reloc_root(rc, root);
2388			if (ret) {
2389				if (list_empty(&reloc_root->root_list))
2390					list_add_tail(&reloc_root->root_list,
2391						      &reloc_roots);
2392				goto out;
2393			}
2394		} else {
2395			list_del_init(&reloc_root->root_list);
2396		}
2397
2398		/*
2399		 * we keep the old last snapshod transid in rtranid when we
2400		 * created the relocation tree.
2401		 */
2402		last_snap = btrfs_root_rtransid(&reloc_root->root_item);
2403		otransid = btrfs_root_otransid(&reloc_root->root_item);
2404		objectid = reloc_root->root_key.offset;
2405
2406		ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2407		if (ret < 0) {
2408			if (list_empty(&reloc_root->root_list))
2409				list_add_tail(&reloc_root->root_list,
2410					      &reloc_roots);
2411			goto out;
2412		}
2413	}
2414
2415	if (found) {
2416		found = 0;
2417		goto again;
2418	}
2419out:
2420	if (ret) {
2421		btrfs_std_error(root->fs_info, ret, NULL);
2422		if (!list_empty(&reloc_roots))
2423			free_reloc_roots(&reloc_roots);
2424
2425		/* new reloc root may be added */
2426		mutex_lock(&root->fs_info->reloc_mutex);
2427		list_splice_init(&rc->reloc_roots, &reloc_roots);
2428		mutex_unlock(&root->fs_info->reloc_mutex);
2429		if (!list_empty(&reloc_roots))
2430			free_reloc_roots(&reloc_roots);
2431	}
2432
2433	BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
 
2434}
2435
2436static void free_block_list(struct rb_root *blocks)
2437{
2438	struct tree_block *block;
2439	struct rb_node *rb_node;
2440	while ((rb_node = rb_first(blocks))) {
2441		block = rb_entry(rb_node, struct tree_block, rb_node);
2442		rb_erase(rb_node, blocks);
2443		kfree(block);
2444	}
2445}
2446
2447static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2448				      struct btrfs_root *reloc_root)
2449{
2450	struct btrfs_root *root;
2451
2452	if (reloc_root->last_trans == trans->transid)
2453		return 0;
2454
2455	root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2456	BUG_ON(IS_ERR(root));
2457	BUG_ON(root->reloc_root != reloc_root);
2458
2459	return btrfs_record_root_in_trans(trans, root);
2460}
2461
2462static noinline_for_stack
2463struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2464				     struct reloc_control *rc,
2465				     struct backref_node *node,
2466				     struct backref_edge *edges[])
2467{
2468	struct backref_node *next;
2469	struct btrfs_root *root;
2470	int index = 0;
2471
2472	next = node;
2473	while (1) {
2474		cond_resched();
2475		next = walk_up_backref(next, edges, &index);
2476		root = next->root;
2477		BUG_ON(!root);
2478		BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2479
2480		if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2481			record_reloc_root_in_trans(trans, root);
2482			break;
2483		}
2484
2485		btrfs_record_root_in_trans(trans, root);
2486		root = root->reloc_root;
2487
2488		if (next->new_bytenr != root->node->start) {
2489			BUG_ON(next->new_bytenr);
2490			BUG_ON(!list_empty(&next->list));
2491			next->new_bytenr = root->node->start;
2492			next->root = root;
2493			list_add_tail(&next->list,
2494				      &rc->backref_cache.changed);
2495			__mark_block_processed(rc, next);
2496			break;
2497		}
2498
2499		WARN_ON(1);
2500		root = NULL;
2501		next = walk_down_backref(edges, &index);
2502		if (!next || next->level <= node->level)
2503			break;
2504	}
2505	if (!root)
2506		return NULL;
2507
 
2508	next = node;
2509	/* setup backref node path for btrfs_reloc_cow_block */
2510	while (1) {
2511		rc->backref_cache.path[next->level] = next;
2512		if (--index < 0)
2513			break;
2514		next = edges[index]->node[UPPER];
2515	}
2516	return root;
2517}
2518
2519/*
2520 * select a tree root for relocation. return NULL if the block
2521 * is reference counted. we should use do_relocation() in this
2522 * case. return a tree root pointer if the block isn't reference
2523 * counted. return -ENOENT if the block is root of reloc tree.
2524 */
2525static noinline_for_stack
2526struct btrfs_root *select_one_root(struct backref_node *node)
 
2527{
2528	struct backref_node *next;
2529	struct btrfs_root *root;
2530	struct btrfs_root *fs_root = NULL;
2531	struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2532	int index = 0;
2533
2534	next = node;
2535	while (1) {
2536		cond_resched();
2537		next = walk_up_backref(next, edges, &index);
2538		root = next->root;
2539		BUG_ON(!root);
2540
2541		/* no other choice for non-references counted tree */
2542		if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2543			return root;
2544
2545		if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2546			fs_root = root;
2547
2548		if (next != node)
2549			return NULL;
2550
2551		next = walk_down_backref(edges, &index);
2552		if (!next || next->level <= node->level)
2553			break;
2554	}
2555
2556	if (!fs_root)
2557		return ERR_PTR(-ENOENT);
2558	return fs_root;
2559}
2560
2561static noinline_for_stack
2562u64 calcu_metadata_size(struct reloc_control *rc,
2563			struct backref_node *node, int reserve)
2564{
2565	struct backref_node *next = node;
2566	struct backref_edge *edge;
2567	struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2568	u64 num_bytes = 0;
2569	int index = 0;
2570
2571	BUG_ON(reserve && node->processed);
2572
2573	while (next) {
2574		cond_resched();
2575		while (1) {
2576			if (next->processed && (reserve || next != node))
2577				break;
2578
2579			num_bytes += rc->extent_root->nodesize;
 
2580
2581			if (list_empty(&next->upper))
2582				break;
2583
2584			edge = list_entry(next->upper.next,
2585					  struct backref_edge, list[LOWER]);
2586			edges[index++] = edge;
2587			next = edge->node[UPPER];
2588		}
2589		next = walk_down_backref(edges, &index);
2590	}
2591	return num_bytes;
2592}
2593
2594static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2595				  struct reloc_control *rc,
2596				  struct backref_node *node)
2597{
2598	struct btrfs_root *root = rc->extent_root;
2599	u64 num_bytes;
2600	int ret;
2601	u64 tmp;
2602
2603	num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2604
2605	trans->block_rsv = rc->block_rsv;
2606	rc->reserved_bytes += num_bytes;
2607	ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2608				BTRFS_RESERVE_FLUSH_ALL);
2609	if (ret) {
2610		if (ret == -EAGAIN) {
2611			tmp = rc->extent_root->nodesize *
2612				RELOCATION_RESERVED_NODES;
2613			while (tmp <= rc->reserved_bytes)
2614				tmp <<= 1;
2615			/*
2616			 * only one thread can access block_rsv at this point,
2617			 * so we don't need hold lock to protect block_rsv.
2618			 * we expand more reservation size here to allow enough
2619			 * space for relocation and we will return eailer in
2620			 * enospc case.
2621			 */
2622			rc->block_rsv->size = tmp + rc->extent_root->nodesize *
2623					      RELOCATION_RESERVED_NODES;
2624		}
2625		return ret;
2626	}
2627
2628	return 0;
2629}
2630
 
 
 
 
 
 
 
2631/*
2632 * relocate a block tree, and then update pointers in upper level
2633 * blocks that reference the block to point to the new location.
2634 *
2635 * if called by link_to_upper, the block has already been relocated.
2636 * in that case this function just updates pointers.
2637 */
2638static int do_relocation(struct btrfs_trans_handle *trans,
2639			 struct reloc_control *rc,
2640			 struct backref_node *node,
2641			 struct btrfs_key *key,
2642			 struct btrfs_path *path, int lowest)
2643{
2644	struct backref_node *upper;
2645	struct backref_edge *edge;
2646	struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2647	struct btrfs_root *root;
2648	struct extent_buffer *eb;
2649	u32 blocksize;
2650	u64 bytenr;
2651	u64 generation;
 
2652	int slot;
2653	int ret;
2654	int err = 0;
2655
2656	BUG_ON(lowest && node->eb);
2657
2658	path->lowest_level = node->level + 1;
2659	rc->backref_cache.path[node->level] = node;
2660	list_for_each_entry(edge, &node->upper, list[LOWER]) {
2661		cond_resched();
2662
2663		upper = edge->node[UPPER];
2664		root = select_reloc_root(trans, rc, upper, edges);
2665		BUG_ON(!root);
2666
2667		if (upper->eb && !upper->locked) {
2668			if (!lowest) {
2669				ret = btrfs_bin_search(upper->eb, key,
2670						       upper->level, &slot);
2671				BUG_ON(ret);
2672				bytenr = btrfs_node_blockptr(upper->eb, slot);
2673				if (node->eb->start == bytenr)
2674					goto next;
2675			}
2676			drop_node_buffer(upper);
2677		}
2678
2679		if (!upper->eb) {
2680			ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2681			if (ret < 0) {
2682				err = ret;
2683				break;
2684			}
2685			BUG_ON(ret > 0);
2686
2687			if (!upper->eb) {
2688				upper->eb = path->nodes[upper->level];
2689				path->nodes[upper->level] = NULL;
2690			} else {
2691				BUG_ON(upper->eb != path->nodes[upper->level]);
2692			}
2693
2694			upper->locked = 1;
2695			path->locks[upper->level] = 0;
2696
2697			slot = path->slots[upper->level];
2698			btrfs_release_path(path);
2699		} else {
2700			ret = btrfs_bin_search(upper->eb, key, upper->level,
2701					       &slot);
2702			BUG_ON(ret);
2703		}
2704
2705		bytenr = btrfs_node_blockptr(upper->eb, slot);
2706		if (lowest) {
2707			BUG_ON(bytenr != node->bytenr);
2708		} else {
2709			if (node->eb->start == bytenr)
2710				goto next;
2711		}
2712
2713		blocksize = root->nodesize;
2714		generation = btrfs_node_ptr_generation(upper->eb, slot);
2715		eb = read_tree_block(root, bytenr, generation);
2716		if (IS_ERR(eb)) {
2717			err = PTR_ERR(eb);
2718			goto next;
2719		} else if (!extent_buffer_uptodate(eb)) {
2720			free_extent_buffer(eb);
2721			err = -EIO;
2722			goto next;
2723		}
2724		btrfs_tree_lock(eb);
2725		btrfs_set_lock_blocking(eb);
2726
2727		if (!node->eb) {
2728			ret = btrfs_cow_block(trans, root, eb, upper->eb,
2729					      slot, &eb);
2730			btrfs_tree_unlock(eb);
2731			free_extent_buffer(eb);
2732			if (ret < 0) {
2733				err = ret;
2734				goto next;
2735			}
2736			BUG_ON(node->eb != eb);
2737		} else {
2738			btrfs_set_node_blockptr(upper->eb, slot,
2739						node->eb->start);
2740			btrfs_set_node_ptr_generation(upper->eb, slot,
2741						      trans->transid);
2742			btrfs_mark_buffer_dirty(upper->eb);
2743
2744			ret = btrfs_inc_extent_ref(trans, root,
2745						node->eb->start, blocksize,
2746						upper->eb->start,
2747						btrfs_header_owner(upper->eb),
2748						node->level, 0);
2749			BUG_ON(ret);
2750
2751			ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2752			BUG_ON(ret);
2753		}
2754next:
2755		if (!upper->pending)
2756			drop_node_buffer(upper);
2757		else
2758			unlock_node_buffer(upper);
2759		if (err)
2760			break;
2761	}
2762
2763	if (!err && node->pending) {
2764		drop_node_buffer(node);
2765		list_move_tail(&node->list, &rc->backref_cache.changed);
2766		node->pending = 0;
2767	}
2768
2769	path->lowest_level = 0;
2770	BUG_ON(err == -ENOSPC);
2771	return err;
2772}
2773
2774static int link_to_upper(struct btrfs_trans_handle *trans,
2775			 struct reloc_control *rc,
2776			 struct backref_node *node,
2777			 struct btrfs_path *path)
2778{
2779	struct btrfs_key key;
2780
2781	btrfs_node_key_to_cpu(node->eb, &key, 0);
2782	return do_relocation(trans, rc, node, &key, path, 0);
2783}
2784
2785static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2786				struct reloc_control *rc,
2787				struct btrfs_path *path, int err)
2788{
2789	LIST_HEAD(list);
2790	struct backref_cache *cache = &rc->backref_cache;
2791	struct backref_node *node;
2792	int level;
2793	int ret;
2794
2795	for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2796		while (!list_empty(&cache->pending[level])) {
2797			node = list_entry(cache->pending[level].next,
2798					  struct backref_node, list);
2799			list_move_tail(&node->list, &list);
2800			BUG_ON(!node->pending);
2801
2802			if (!err) {
2803				ret = link_to_upper(trans, rc, node, path);
2804				if (ret < 0)
2805					err = ret;
2806			}
2807		}
2808		list_splice_init(&list, &cache->pending[level]);
2809	}
2810	return err;
2811}
2812
2813static void mark_block_processed(struct reloc_control *rc,
2814				 u64 bytenr, u32 blocksize)
2815{
2816	set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2817			EXTENT_DIRTY, GFP_NOFS);
2818}
2819
2820static void __mark_block_processed(struct reloc_control *rc,
2821				   struct backref_node *node)
2822{
2823	u32 blocksize;
2824	if (node->level == 0 ||
2825	    in_block_group(node->bytenr, rc->block_group)) {
2826		blocksize = rc->extent_root->nodesize;
2827		mark_block_processed(rc, node->bytenr, blocksize);
2828	}
2829	node->processed = 1;
2830}
2831
2832/*
2833 * mark a block and all blocks directly/indirectly reference the block
2834 * as processed.
2835 */
2836static void update_processed_blocks(struct reloc_control *rc,
2837				    struct backref_node *node)
2838{
2839	struct backref_node *next = node;
2840	struct backref_edge *edge;
2841	struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2842	int index = 0;
2843
2844	while (next) {
2845		cond_resched();
2846		while (1) {
2847			if (next->processed)
2848				break;
2849
2850			__mark_block_processed(rc, next);
2851
2852			if (list_empty(&next->upper))
2853				break;
2854
2855			edge = list_entry(next->upper.next,
2856					  struct backref_edge, list[LOWER]);
2857			edges[index++] = edge;
2858			next = edge->node[UPPER];
2859		}
2860		next = walk_down_backref(edges, &index);
2861	}
2862}
2863
2864static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
 
2865{
2866	u32 blocksize = rc->extent_root->nodesize;
2867
2868	if (test_range_bit(&rc->processed_blocks, bytenr,
2869			   bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2870		return 1;
2871	return 0;
2872}
2873
2874static int get_tree_block_key(struct reloc_control *rc,
2875			      struct tree_block *block)
2876{
2877	struct extent_buffer *eb;
2878
2879	BUG_ON(block->key_ready);
2880	eb = read_tree_block(rc->extent_root, block->bytenr,
2881			     block->key.offset);
2882	if (IS_ERR(eb)) {
2883		return PTR_ERR(eb);
2884	} else if (!extent_buffer_uptodate(eb)) {
2885		free_extent_buffer(eb);
2886		return -EIO;
2887	}
2888	WARN_ON(btrfs_header_level(eb) != block->level);
2889	if (block->level == 0)
2890		btrfs_item_key_to_cpu(eb, &block->key, 0);
2891	else
2892		btrfs_node_key_to_cpu(eb, &block->key, 0);
2893	free_extent_buffer(eb);
2894	block->key_ready = 1;
2895	return 0;
2896}
2897
 
 
 
 
 
 
 
 
 
2898/*
2899 * helper function to relocate a tree block
2900 */
2901static int relocate_tree_block(struct btrfs_trans_handle *trans,
2902				struct reloc_control *rc,
2903				struct backref_node *node,
2904				struct btrfs_key *key,
2905				struct btrfs_path *path)
2906{
2907	struct btrfs_root *root;
 
2908	int ret = 0;
2909
2910	if (!node)
2911		return 0;
2912
2913	BUG_ON(node->processed);
2914	root = select_one_root(node);
2915	if (root == ERR_PTR(-ENOENT)) {
2916		update_processed_blocks(rc, node);
2917		goto out;
2918	}
2919
2920	if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2921		ret = reserve_metadata_space(trans, rc, node);
2922		if (ret)
2923			goto out;
 
2924	}
2925
2926	if (root) {
2927		if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2928			BUG_ON(node->new_bytenr);
2929			BUG_ON(!list_empty(&node->list));
2930			btrfs_record_root_in_trans(trans, root);
2931			root = root->reloc_root;
2932			node->new_bytenr = root->node->start;
2933			node->root = root;
2934			list_add_tail(&node->list, &rc->backref_cache.changed);
2935		} else {
2936			path->lowest_level = node->level;
2937			ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2938			btrfs_release_path(path);
2939			if (ret > 0)
2940				ret = 0;
2941		}
2942		if (!ret)
2943			update_processed_blocks(rc, node);
2944	} else {
2945		ret = do_relocation(trans, rc, node, key, path, 1);
2946	}
2947out:
2948	if (ret || node->level == 0 || node->cowonly)
 
 
2949		remove_backref_node(&rc->backref_cache, node);
 
2950	return ret;
2951}
2952
2953/*
2954 * relocate a list of blocks
2955 */
2956static noinline_for_stack
2957int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2958			 struct reloc_control *rc, struct rb_root *blocks)
2959{
2960	struct backref_node *node;
2961	struct btrfs_path *path;
2962	struct tree_block *block;
2963	struct rb_node *rb_node;
2964	int ret;
2965	int err = 0;
2966
2967	path = btrfs_alloc_path();
2968	if (!path) {
2969		err = -ENOMEM;
2970		goto out_free_blocks;
2971	}
2972
2973	rb_node = rb_first(blocks);
2974	while (rb_node) {
2975		block = rb_entry(rb_node, struct tree_block, rb_node);
2976		if (!block->key_ready)
2977			readahead_tree_block(rc->extent_root, block->bytenr);
2978		rb_node = rb_next(rb_node);
2979	}
2980
2981	rb_node = rb_first(blocks);
2982	while (rb_node) {
2983		block = rb_entry(rb_node, struct tree_block, rb_node);
2984		if (!block->key_ready) {
2985			err = get_tree_block_key(rc, block);
2986			if (err)
2987				goto out_free_path;
2988		}
2989		rb_node = rb_next(rb_node);
2990	}
2991
2992	rb_node = rb_first(blocks);
2993	while (rb_node) {
2994		block = rb_entry(rb_node, struct tree_block, rb_node);
2995
2996		node = build_backref_tree(rc, &block->key,
2997					  block->level, block->bytenr);
2998		if (IS_ERR(node)) {
2999			err = PTR_ERR(node);
3000			goto out;
3001		}
3002
3003		ret = relocate_tree_block(trans, rc, node, &block->key,
3004					  path);
3005		if (ret < 0) {
3006			if (ret != -EAGAIN || rb_node == rb_first(blocks))
3007				err = ret;
3008			goto out;
3009		}
3010		rb_node = rb_next(rb_node);
3011	}
3012out:
 
3013	err = finish_pending_nodes(trans, rc, path, err);
3014
3015out_free_path:
3016	btrfs_free_path(path);
3017out_free_blocks:
3018	free_block_list(blocks);
3019	return err;
3020}
3021
3022static noinline_for_stack
3023int prealloc_file_extent_cluster(struct inode *inode,
3024				 struct file_extent_cluster *cluster)
3025{
3026	u64 alloc_hint = 0;
3027	u64 start;
3028	u64 end;
3029	u64 offset = BTRFS_I(inode)->index_cnt;
3030	u64 num_bytes;
3031	int nr = 0;
3032	int ret = 0;
3033
3034	BUG_ON(cluster->start != cluster->boundary[0]);
3035	inode_lock(inode);
3036
3037	ret = btrfs_check_data_free_space(inode, cluster->start,
3038					  cluster->end + 1 - cluster->start);
3039	if (ret)
3040		goto out;
3041
3042	while (nr < cluster->nr) {
3043		start = cluster->boundary[nr] - offset;
3044		if (nr + 1 < cluster->nr)
3045			end = cluster->boundary[nr + 1] - 1 - offset;
3046		else
3047			end = cluster->end - offset;
3048
3049		lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3050		num_bytes = end + 1 - start;
3051		ret = btrfs_prealloc_file_range(inode, 0, start,
3052						num_bytes, num_bytes,
3053						end + 1, &alloc_hint);
3054		unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3055		if (ret)
3056			break;
3057		nr++;
3058	}
3059	btrfs_free_reserved_data_space(inode, cluster->start,
3060				       cluster->end + 1 - cluster->start);
3061out:
3062	inode_unlock(inode);
3063	return ret;
3064}
3065
3066static noinline_for_stack
3067int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3068			 u64 block_start)
3069{
3070	struct btrfs_root *root = BTRFS_I(inode)->root;
3071	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3072	struct extent_map *em;
3073	int ret = 0;
3074
3075	em = alloc_extent_map();
3076	if (!em)
3077		return -ENOMEM;
3078
3079	em->start = start;
3080	em->len = end + 1 - start;
3081	em->block_len = em->len;
3082	em->block_start = block_start;
3083	em->bdev = root->fs_info->fs_devices->latest_bdev;
3084	set_bit(EXTENT_FLAG_PINNED, &em->flags);
3085
3086	lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3087	while (1) {
3088		write_lock(&em_tree->lock);
3089		ret = add_extent_mapping(em_tree, em, 0);
3090		write_unlock(&em_tree->lock);
3091		if (ret != -EEXIST) {
3092			free_extent_map(em);
3093			break;
3094		}
3095		btrfs_drop_extent_cache(inode, start, end, 0);
3096	}
3097	unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3098	return ret;
3099}
3100
3101static int relocate_file_extent_cluster(struct inode *inode,
3102					struct file_extent_cluster *cluster)
3103{
3104	u64 page_start;
3105	u64 page_end;
3106	u64 offset = BTRFS_I(inode)->index_cnt;
3107	unsigned long index;
3108	unsigned long last_index;
3109	struct page *page;
3110	struct file_ra_state *ra;
3111	gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3112	int nr = 0;
3113	int ret = 0;
3114
3115	if (!cluster->nr)
3116		return 0;
3117
3118	ra = kzalloc(sizeof(*ra), GFP_NOFS);
3119	if (!ra)
3120		return -ENOMEM;
3121
3122	ret = prealloc_file_extent_cluster(inode, cluster);
3123	if (ret)
3124		goto out;
3125
3126	file_ra_state_init(ra, inode->i_mapping);
3127
3128	ret = setup_extent_mapping(inode, cluster->start - offset,
3129				   cluster->end - offset, cluster->start);
3130	if (ret)
3131		goto out;
3132
3133	index = (cluster->start - offset) >> PAGE_SHIFT;
3134	last_index = (cluster->end - offset) >> PAGE_SHIFT;
3135	while (index <= last_index) {
3136		ret = btrfs_delalloc_reserve_metadata(inode, PAGE_SIZE);
3137		if (ret)
3138			goto out;
3139
3140		page = find_lock_page(inode->i_mapping, index);
3141		if (!page) {
3142			page_cache_sync_readahead(inode->i_mapping,
3143						  ra, NULL, index,
3144						  last_index + 1 - index);
3145			page = find_or_create_page(inode->i_mapping, index,
3146						   mask);
3147			if (!page) {
3148				btrfs_delalloc_release_metadata(inode,
3149							PAGE_SIZE);
3150				ret = -ENOMEM;
3151				goto out;
3152			}
3153		}
3154
3155		if (PageReadahead(page)) {
3156			page_cache_async_readahead(inode->i_mapping,
3157						   ra, NULL, page, index,
3158						   last_index + 1 - index);
3159		}
3160
3161		if (!PageUptodate(page)) {
3162			btrfs_readpage(NULL, page);
3163			lock_page(page);
3164			if (!PageUptodate(page)) {
3165				unlock_page(page);
3166				put_page(page);
3167				btrfs_delalloc_release_metadata(inode,
3168							PAGE_SIZE);
3169				ret = -EIO;
3170				goto out;
3171			}
3172		}
3173
3174		page_start = page_offset(page);
3175		page_end = page_start + PAGE_SIZE - 1;
3176
3177		lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
 
3178
3179		set_page_extent_mapped(page);
3180
3181		if (nr < cluster->nr &&
3182		    page_start + offset == cluster->boundary[nr]) {
3183			set_extent_bits(&BTRFS_I(inode)->io_tree,
3184					page_start, page_end,
3185					EXTENT_BOUNDARY, GFP_NOFS);
3186			nr++;
3187		}
3188
3189		btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3190		set_page_dirty(page);
3191
3192		unlock_extent(&BTRFS_I(inode)->io_tree,
3193			      page_start, page_end);
3194		unlock_page(page);
3195		put_page(page);
3196
3197		index++;
3198		balance_dirty_pages_ratelimited(inode->i_mapping);
3199		btrfs_throttle(BTRFS_I(inode)->root);
3200	}
3201	WARN_ON(nr != cluster->nr);
3202out:
3203	kfree(ra);
3204	return ret;
3205}
3206
3207static noinline_for_stack
3208int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3209			 struct file_extent_cluster *cluster)
3210{
3211	int ret;
3212
3213	if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3214		ret = relocate_file_extent_cluster(inode, cluster);
3215		if (ret)
3216			return ret;
3217		cluster->nr = 0;
3218	}
3219
3220	if (!cluster->nr)
3221		cluster->start = extent_key->objectid;
3222	else
3223		BUG_ON(cluster->nr >= MAX_EXTENTS);
3224	cluster->end = extent_key->objectid + extent_key->offset - 1;
3225	cluster->boundary[cluster->nr] = extent_key->objectid;
3226	cluster->nr++;
3227
3228	if (cluster->nr >= MAX_EXTENTS) {
3229		ret = relocate_file_extent_cluster(inode, cluster);
3230		if (ret)
3231			return ret;
3232		cluster->nr = 0;
3233	}
3234	return 0;
3235}
3236
3237#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3238static int get_ref_objectid_v0(struct reloc_control *rc,
3239			       struct btrfs_path *path,
3240			       struct btrfs_key *extent_key,
3241			       u64 *ref_objectid, int *path_change)
3242{
3243	struct btrfs_key key;
3244	struct extent_buffer *leaf;
3245	struct btrfs_extent_ref_v0 *ref0;
3246	int ret;
3247	int slot;
3248
3249	leaf = path->nodes[0];
3250	slot = path->slots[0];
3251	while (1) {
3252		if (slot >= btrfs_header_nritems(leaf)) {
3253			ret = btrfs_next_leaf(rc->extent_root, path);
3254			if (ret < 0)
3255				return ret;
3256			BUG_ON(ret > 0);
3257			leaf = path->nodes[0];
3258			slot = path->slots[0];
3259			if (path_change)
3260				*path_change = 1;
3261		}
3262		btrfs_item_key_to_cpu(leaf, &key, slot);
3263		if (key.objectid != extent_key->objectid)
3264			return -ENOENT;
3265
3266		if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3267			slot++;
3268			continue;
3269		}
3270		ref0 = btrfs_item_ptr(leaf, slot,
3271				struct btrfs_extent_ref_v0);
3272		*ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3273		break;
3274	}
3275	return 0;
3276}
3277#endif
3278
3279/*
3280 * helper to add a tree block to the list.
3281 * the major work is getting the generation and level of the block
3282 */
3283static int add_tree_block(struct reloc_control *rc,
3284			  struct btrfs_key *extent_key,
3285			  struct btrfs_path *path,
3286			  struct rb_root *blocks)
3287{
3288	struct extent_buffer *eb;
3289	struct btrfs_extent_item *ei;
3290	struct btrfs_tree_block_info *bi;
3291	struct tree_block *block;
3292	struct rb_node *rb_node;
3293	u32 item_size;
3294	int level = -1;
3295	u64 generation;
3296
3297	eb =  path->nodes[0];
3298	item_size = btrfs_item_size_nr(eb, path->slots[0]);
3299
3300	if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3301	    item_size >= sizeof(*ei) + sizeof(*bi)) {
3302		ei = btrfs_item_ptr(eb, path->slots[0],
3303				struct btrfs_extent_item);
3304		if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3305			bi = (struct btrfs_tree_block_info *)(ei + 1);
3306			level = btrfs_tree_block_level(eb, bi);
3307		} else {
3308			level = (int)extent_key->offset;
3309		}
3310		generation = btrfs_extent_generation(eb, ei);
 
3311	} else {
3312#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3313		u64 ref_owner;
3314		int ret;
3315
3316		BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3317		ret = get_ref_objectid_v0(rc, path, extent_key,
3318					  &ref_owner, NULL);
3319		if (ret < 0)
3320			return ret;
3321		BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3322		level = (int)ref_owner;
3323		/* FIXME: get real generation */
3324		generation = 0;
3325#else
3326		BUG();
3327#endif
3328	}
3329
3330	btrfs_release_path(path);
3331
3332	BUG_ON(level == -1);
3333
3334	block = kmalloc(sizeof(*block), GFP_NOFS);
3335	if (!block)
3336		return -ENOMEM;
3337
3338	block->bytenr = extent_key->objectid;
3339	block->key.objectid = rc->extent_root->nodesize;
3340	block->key.offset = generation;
3341	block->level = level;
3342	block->key_ready = 0;
3343
3344	rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3345	if (rb_node)
3346		backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3347
3348	return 0;
3349}
3350
3351/*
3352 * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3353 */
3354static int __add_tree_block(struct reloc_control *rc,
3355			    u64 bytenr, u32 blocksize,
3356			    struct rb_root *blocks)
3357{
3358	struct btrfs_path *path;
3359	struct btrfs_key key;
3360	int ret;
3361	bool skinny = btrfs_fs_incompat(rc->extent_root->fs_info,
3362					SKINNY_METADATA);
3363
3364	if (tree_block_processed(bytenr, rc))
3365		return 0;
3366
3367	if (tree_search(blocks, bytenr))
3368		return 0;
3369
3370	path = btrfs_alloc_path();
3371	if (!path)
3372		return -ENOMEM;
3373again:
3374	key.objectid = bytenr;
3375	if (skinny) {
3376		key.type = BTRFS_METADATA_ITEM_KEY;
3377		key.offset = (u64)-1;
3378	} else {
3379		key.type = BTRFS_EXTENT_ITEM_KEY;
3380		key.offset = blocksize;
3381	}
3382
3383	path->search_commit_root = 1;
3384	path->skip_locking = 1;
3385	ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3386	if (ret < 0)
3387		goto out;
3388
3389	if (ret > 0 && skinny) {
3390		if (path->slots[0]) {
3391			path->slots[0]--;
3392			btrfs_item_key_to_cpu(path->nodes[0], &key,
3393					      path->slots[0]);
3394			if (key.objectid == bytenr &&
3395			    (key.type == BTRFS_METADATA_ITEM_KEY ||
3396			     (key.type == BTRFS_EXTENT_ITEM_KEY &&
3397			      key.offset == blocksize)))
3398				ret = 0;
3399		}
3400
3401		if (ret) {
3402			skinny = false;
3403			btrfs_release_path(path);
3404			goto again;
3405		}
3406	}
3407	BUG_ON(ret);
3408
 
3409	ret = add_tree_block(rc, &key, path, blocks);
3410out:
3411	btrfs_free_path(path);
3412	return ret;
3413}
3414
3415/*
3416 * helper to check if the block use full backrefs for pointers in it
3417 */
3418static int block_use_full_backref(struct reloc_control *rc,
3419				  struct extent_buffer *eb)
3420{
3421	u64 flags;
3422	int ret;
3423
3424	if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3425	    btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3426		return 1;
3427
3428	ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3429				       eb->start, btrfs_header_level(eb), 1,
3430				       NULL, &flags);
3431	BUG_ON(ret);
3432
3433	if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3434		ret = 1;
3435	else
3436		ret = 0;
3437	return ret;
3438}
3439
3440static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3441				    struct btrfs_block_group_cache *block_group,
3442				    struct inode *inode,
3443				    u64 ino)
3444{
3445	struct btrfs_key key;
 
3446	struct btrfs_root *root = fs_info->tree_root;
3447	struct btrfs_trans_handle *trans;
 
3448	int ret = 0;
3449
3450	if (inode)
3451		goto truncate;
3452
3453	key.objectid = ino;
3454	key.type = BTRFS_INODE_ITEM_KEY;
3455	key.offset = 0;
3456
3457	inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3458	if (IS_ERR(inode) || is_bad_inode(inode)) {
3459		if (!IS_ERR(inode))
3460			iput(inode);
3461		return -ENOENT;
3462	}
3463
3464truncate:
3465	ret = btrfs_check_trunc_cache_free_space(root,
3466						 &fs_info->global_block_rsv);
3467	if (ret)
3468		goto out;
 
3469
3470	trans = btrfs_join_transaction(root);
3471	if (IS_ERR(trans)) {
 
3472		ret = PTR_ERR(trans);
3473		goto out;
3474	}
3475
3476	ret = btrfs_truncate_free_space_cache(root, trans, block_group, inode);
3477
 
 
3478	btrfs_end_transaction(trans, root);
3479	btrfs_btree_balance_dirty(root);
3480out:
3481	iput(inode);
3482	return ret;
3483}
3484
3485/*
3486 * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3487 * this function scans fs tree to find blocks reference the data extent
3488 */
3489static int find_data_references(struct reloc_control *rc,
3490				struct btrfs_key *extent_key,
3491				struct extent_buffer *leaf,
3492				struct btrfs_extent_data_ref *ref,
3493				struct rb_root *blocks)
3494{
3495	struct btrfs_path *path;
3496	struct tree_block *block;
3497	struct btrfs_root *root;
3498	struct btrfs_file_extent_item *fi;
3499	struct rb_node *rb_node;
3500	struct btrfs_key key;
3501	u64 ref_root;
3502	u64 ref_objectid;
3503	u64 ref_offset;
3504	u32 ref_count;
3505	u32 nritems;
3506	int err = 0;
3507	int added = 0;
3508	int counted;
3509	int ret;
3510
3511	ref_root = btrfs_extent_data_ref_root(leaf, ref);
3512	ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3513	ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3514	ref_count = btrfs_extent_data_ref_count(leaf, ref);
3515
3516	/*
3517	 * This is an extent belonging to the free space cache, lets just delete
3518	 * it and redo the search.
3519	 */
3520	if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3521		ret = delete_block_group_cache(rc->extent_root->fs_info,
3522					       rc->block_group,
3523					       NULL, ref_objectid);
3524		if (ret != -ENOENT)
3525			return ret;
3526		ret = 0;
3527	}
3528
3529	path = btrfs_alloc_path();
3530	if (!path)
3531		return -ENOMEM;
3532	path->reada = READA_FORWARD;
3533
3534	root = read_fs_root(rc->extent_root->fs_info, ref_root);
3535	if (IS_ERR(root)) {
3536		err = PTR_ERR(root);
3537		goto out;
3538	}
3539
3540	key.objectid = ref_objectid;
 
3541	key.type = BTRFS_EXTENT_DATA_KEY;
3542	if (ref_offset > ((u64)-1 << 32))
3543		key.offset = 0;
3544	else
3545		key.offset = ref_offset;
3546
3547	path->search_commit_root = 1;
3548	path->skip_locking = 1;
3549	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3550	if (ret < 0) {
3551		err = ret;
3552		goto out;
3553	}
3554
3555	leaf = path->nodes[0];
3556	nritems = btrfs_header_nritems(leaf);
3557	/*
3558	 * the references in tree blocks that use full backrefs
3559	 * are not counted in
3560	 */
3561	if (block_use_full_backref(rc, leaf))
3562		counted = 0;
3563	else
3564		counted = 1;
3565	rb_node = tree_search(blocks, leaf->start);
3566	if (rb_node) {
3567		if (counted)
3568			added = 1;
3569		else
3570			path->slots[0] = nritems;
3571	}
3572
3573	while (ref_count > 0) {
3574		while (path->slots[0] >= nritems) {
3575			ret = btrfs_next_leaf(root, path);
3576			if (ret < 0) {
3577				err = ret;
3578				goto out;
3579			}
3580			if (WARN_ON(ret > 0))
 
3581				goto out;
 
3582
3583			leaf = path->nodes[0];
3584			nritems = btrfs_header_nritems(leaf);
3585			added = 0;
3586
3587			if (block_use_full_backref(rc, leaf))
3588				counted = 0;
3589			else
3590				counted = 1;
3591			rb_node = tree_search(blocks, leaf->start);
3592			if (rb_node) {
3593				if (counted)
3594					added = 1;
3595				else
3596					path->slots[0] = nritems;
3597			}
3598		}
3599
3600		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3601		if (WARN_ON(key.objectid != ref_objectid ||
3602		    key.type != BTRFS_EXTENT_DATA_KEY))
 
3603			break;
 
3604
3605		fi = btrfs_item_ptr(leaf, path->slots[0],
3606				    struct btrfs_file_extent_item);
3607
3608		if (btrfs_file_extent_type(leaf, fi) ==
3609		    BTRFS_FILE_EXTENT_INLINE)
3610			goto next;
3611
3612		if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3613		    extent_key->objectid)
3614			goto next;
3615
3616		key.offset -= btrfs_file_extent_offset(leaf, fi);
3617		if (key.offset != ref_offset)
3618			goto next;
3619
3620		if (counted)
3621			ref_count--;
3622		if (added)
3623			goto next;
3624
3625		if (!tree_block_processed(leaf->start, rc)) {
3626			block = kmalloc(sizeof(*block), GFP_NOFS);
3627			if (!block) {
3628				err = -ENOMEM;
3629				break;
3630			}
3631			block->bytenr = leaf->start;
3632			btrfs_item_key_to_cpu(leaf, &block->key, 0);
3633			block->level = 0;
3634			block->key_ready = 1;
3635			rb_node = tree_insert(blocks, block->bytenr,
3636					      &block->rb_node);
3637			if (rb_node)
3638				backref_tree_panic(rb_node, -EEXIST,
3639						   block->bytenr);
3640		}
3641		if (counted)
3642			added = 1;
3643		else
3644			path->slots[0] = nritems;
3645next:
3646		path->slots[0]++;
3647
3648	}
3649out:
3650	btrfs_free_path(path);
3651	return err;
3652}
3653
3654/*
3655 * helper to find all tree blocks that reference a given data extent
3656 */
3657static noinline_for_stack
3658int add_data_references(struct reloc_control *rc,
3659			struct btrfs_key *extent_key,
3660			struct btrfs_path *path,
3661			struct rb_root *blocks)
3662{
3663	struct btrfs_key key;
3664	struct extent_buffer *eb;
3665	struct btrfs_extent_data_ref *dref;
3666	struct btrfs_extent_inline_ref *iref;
3667	unsigned long ptr;
3668	unsigned long end;
3669	u32 blocksize = rc->extent_root->nodesize;
3670	int ret = 0;
3671	int err = 0;
3672
3673	eb = path->nodes[0];
3674	ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3675	end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3676#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3677	if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3678		ptr = end;
3679	else
3680#endif
3681		ptr += sizeof(struct btrfs_extent_item);
3682
3683	while (ptr < end) {
3684		iref = (struct btrfs_extent_inline_ref *)ptr;
3685		key.type = btrfs_extent_inline_ref_type(eb, iref);
3686		if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3687			key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3688			ret = __add_tree_block(rc, key.offset, blocksize,
3689					       blocks);
3690		} else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3691			dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3692			ret = find_data_references(rc, extent_key,
3693						   eb, dref, blocks);
3694		} else {
3695			BUG();
3696		}
3697		if (ret) {
3698			err = ret;
3699			goto out;
3700		}
3701		ptr += btrfs_extent_inline_ref_size(key.type);
3702	}
3703	WARN_ON(ptr > end);
3704
3705	while (1) {
3706		cond_resched();
3707		eb = path->nodes[0];
3708		if (path->slots[0] >= btrfs_header_nritems(eb)) {
3709			ret = btrfs_next_leaf(rc->extent_root, path);
3710			if (ret < 0) {
3711				err = ret;
3712				break;
3713			}
3714			if (ret > 0)
3715				break;
3716			eb = path->nodes[0];
3717		}
3718
3719		btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3720		if (key.objectid != extent_key->objectid)
3721			break;
3722
3723#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3724		if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3725		    key.type == BTRFS_EXTENT_REF_V0_KEY) {
3726#else
3727		BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3728		if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3729#endif
3730			ret = __add_tree_block(rc, key.offset, blocksize,
3731					       blocks);
3732		} else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3733			dref = btrfs_item_ptr(eb, path->slots[0],
3734					      struct btrfs_extent_data_ref);
3735			ret = find_data_references(rc, extent_key,
3736						   eb, dref, blocks);
3737		} else {
3738			ret = 0;
3739		}
3740		if (ret) {
3741			err = ret;
3742			break;
3743		}
3744		path->slots[0]++;
3745	}
3746out:
3747	btrfs_release_path(path);
3748	if (err)
3749		free_block_list(blocks);
3750	return err;
3751}
3752
3753/*
3754 * helper to find next unprocessed extent
3755 */
3756static noinline_for_stack
3757int find_next_extent(struct reloc_control *rc, struct btrfs_path *path,
 
3758		     struct btrfs_key *extent_key)
3759{
3760	struct btrfs_key key;
3761	struct extent_buffer *leaf;
3762	u64 start, end, last;
3763	int ret;
3764
3765	last = rc->block_group->key.objectid + rc->block_group->key.offset;
3766	while (1) {
3767		cond_resched();
3768		if (rc->search_start >= last) {
3769			ret = 1;
3770			break;
3771		}
3772
3773		key.objectid = rc->search_start;
3774		key.type = BTRFS_EXTENT_ITEM_KEY;
3775		key.offset = 0;
3776
3777		path->search_commit_root = 1;
3778		path->skip_locking = 1;
3779		ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3780					0, 0);
3781		if (ret < 0)
3782			break;
3783next:
3784		leaf = path->nodes[0];
3785		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3786			ret = btrfs_next_leaf(rc->extent_root, path);
3787			if (ret != 0)
3788				break;
3789			leaf = path->nodes[0];
3790		}
3791
3792		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3793		if (key.objectid >= last) {
3794			ret = 1;
3795			break;
3796		}
3797
3798		if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3799		    key.type != BTRFS_METADATA_ITEM_KEY) {
3800			path->slots[0]++;
3801			goto next;
3802		}
3803
3804		if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3805		    key.objectid + key.offset <= rc->search_start) {
3806			path->slots[0]++;
3807			goto next;
3808		}
3809
3810		if (key.type == BTRFS_METADATA_ITEM_KEY &&
3811		    key.objectid + rc->extent_root->nodesize <=
3812		    rc->search_start) {
3813			path->slots[0]++;
3814			goto next;
3815		}
3816
3817		ret = find_first_extent_bit(&rc->processed_blocks,
3818					    key.objectid, &start, &end,
3819					    EXTENT_DIRTY, NULL);
3820
3821		if (ret == 0 && start <= key.objectid) {
3822			btrfs_release_path(path);
3823			rc->search_start = end + 1;
3824		} else {
3825			if (key.type == BTRFS_EXTENT_ITEM_KEY)
3826				rc->search_start = key.objectid + key.offset;
3827			else
3828				rc->search_start = key.objectid +
3829					rc->extent_root->nodesize;
3830			memcpy(extent_key, &key, sizeof(key));
3831			return 0;
3832		}
3833	}
3834	btrfs_release_path(path);
3835	return ret;
3836}
3837
3838static void set_reloc_control(struct reloc_control *rc)
3839{
3840	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3841
3842	mutex_lock(&fs_info->reloc_mutex);
3843	fs_info->reloc_ctl = rc;
3844	mutex_unlock(&fs_info->reloc_mutex);
3845}
3846
3847static void unset_reloc_control(struct reloc_control *rc)
3848{
3849	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3850
3851	mutex_lock(&fs_info->reloc_mutex);
3852	fs_info->reloc_ctl = NULL;
3853	mutex_unlock(&fs_info->reloc_mutex);
3854}
3855
3856static int check_extent_flags(u64 flags)
3857{
3858	if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3859	    (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3860		return 1;
3861	if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3862	    !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3863		return 1;
3864	if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3865	    (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3866		return 1;
3867	return 0;
3868}
3869
3870static noinline_for_stack
3871int prepare_to_relocate(struct reloc_control *rc)
3872{
3873	struct btrfs_trans_handle *trans;
 
3874
3875	rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3876					      BTRFS_BLOCK_RSV_TEMP);
3877	if (!rc->block_rsv)
3878		return -ENOMEM;
3879
 
 
 
 
 
 
 
 
 
 
 
 
 
3880	memset(&rc->cluster, 0, sizeof(rc->cluster));
3881	rc->search_start = rc->block_group->key.objectid;
3882	rc->extents_found = 0;
3883	rc->nodes_relocated = 0;
3884	rc->merging_rsv_size = 0;
3885	rc->reserved_bytes = 0;
3886	rc->block_rsv->size = rc->extent_root->nodesize *
3887			      RELOCATION_RESERVED_NODES;
3888
3889	rc->create_reloc_tree = 1;
3890	set_reloc_control(rc);
3891
3892	trans = btrfs_join_transaction(rc->extent_root);
3893	if (IS_ERR(trans)) {
3894		unset_reloc_control(rc);
3895		/*
3896		 * extent tree is not a ref_cow tree and has no reloc_root to
3897		 * cleanup.  And callers are responsible to free the above
3898		 * block rsv.
3899		 */
3900		return PTR_ERR(trans);
3901	}
3902	btrfs_commit_transaction(trans, rc->extent_root);
3903	return 0;
3904}
3905
3906static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3907{
3908	struct rb_root blocks = RB_ROOT;
3909	struct btrfs_key key;
3910	struct btrfs_trans_handle *trans = NULL;
3911	struct btrfs_path *path;
3912	struct btrfs_extent_item *ei;
 
3913	u64 flags;
3914	u32 item_size;
3915	int ret;
3916	int err = 0;
3917	int progress = 0;
3918
3919	path = btrfs_alloc_path();
3920	if (!path)
3921		return -ENOMEM;
3922	path->reada = READA_FORWARD;
3923
3924	ret = prepare_to_relocate(rc);
3925	if (ret) {
3926		err = ret;
3927		goto out_free;
3928	}
3929
3930	while (1) {
3931		rc->reserved_bytes = 0;
3932		ret = btrfs_block_rsv_refill(rc->extent_root,
3933					rc->block_rsv, rc->block_rsv->size,
3934					BTRFS_RESERVE_FLUSH_ALL);
3935		if (ret) {
3936			err = ret;
3937			break;
3938		}
3939		progress++;
3940		trans = btrfs_start_transaction(rc->extent_root, 0);
3941		if (IS_ERR(trans)) {
3942			err = PTR_ERR(trans);
3943			trans = NULL;
3944			break;
3945		}
3946restart:
3947		if (update_backref_cache(trans, &rc->backref_cache)) {
3948			btrfs_end_transaction(trans, rc->extent_root);
3949			continue;
3950		}
3951
3952		ret = find_next_extent(rc, path, &key);
3953		if (ret < 0)
3954			err = ret;
3955		if (ret != 0)
3956			break;
3957
3958		rc->extents_found++;
3959
3960		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3961				    struct btrfs_extent_item);
3962		item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3963		if (item_size >= sizeof(*ei)) {
3964			flags = btrfs_extent_flags(path->nodes[0], ei);
3965			ret = check_extent_flags(flags);
3966			BUG_ON(ret);
3967
3968		} else {
3969#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3970			u64 ref_owner;
3971			int path_change = 0;
3972
3973			BUG_ON(item_size !=
3974			       sizeof(struct btrfs_extent_item_v0));
3975			ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3976						  &path_change);
3977			if (ret < 0) {
3978				err = ret;
3979				break;
3980			}
3981			if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3982				flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3983			else
3984				flags = BTRFS_EXTENT_FLAG_DATA;
3985
3986			if (path_change) {
3987				btrfs_release_path(path);
3988
3989				path->search_commit_root = 1;
3990				path->skip_locking = 1;
3991				ret = btrfs_search_slot(NULL, rc->extent_root,
3992							&key, path, 0, 0);
3993				if (ret < 0) {
3994					err = ret;
3995					break;
3996				}
3997				BUG_ON(ret > 0);
3998			}
3999#else
4000			BUG();
4001#endif
4002		}
4003
4004		if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
4005			ret = add_tree_block(rc, &key, path, &blocks);
4006		} else if (rc->stage == UPDATE_DATA_PTRS &&
4007			   (flags & BTRFS_EXTENT_FLAG_DATA)) {
4008			ret = add_data_references(rc, &key, path, &blocks);
4009		} else {
4010			btrfs_release_path(path);
4011			ret = 0;
4012		}
4013		if (ret < 0) {
4014			err = ret;
4015			break;
4016		}
4017
4018		if (!RB_EMPTY_ROOT(&blocks)) {
4019			ret = relocate_tree_blocks(trans, rc, &blocks);
4020			if (ret < 0) {
4021				/*
4022				 * if we fail to relocate tree blocks, force to update
4023				 * backref cache when committing transaction.
4024				 */
4025				rc->backref_cache.last_trans = trans->transid - 1;
4026
4027				if (ret != -EAGAIN) {
4028					err = ret;
4029					break;
4030				}
4031				rc->extents_found--;
4032				rc->search_start = key.objectid;
4033			}
4034		}
4035
4036		btrfs_end_transaction_throttle(trans, rc->extent_root);
4037		btrfs_btree_balance_dirty(rc->extent_root);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4038		trans = NULL;
4039
4040		if (rc->stage == MOVE_DATA_EXTENTS &&
4041		    (flags & BTRFS_EXTENT_FLAG_DATA)) {
4042			rc->found_file_extent = 1;
4043			ret = relocate_data_extent(rc->data_inode,
4044						   &key, &rc->cluster);
4045			if (ret < 0) {
4046				err = ret;
4047				break;
4048			}
4049		}
4050	}
4051	if (trans && progress && err == -ENOSPC) {
4052		ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
4053					      rc->block_group->flags);
4054		if (ret == 1) {
4055			err = 0;
4056			progress = 0;
4057			goto restart;
4058		}
4059	}
4060
4061	btrfs_release_path(path);
4062	clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
4063			  GFP_NOFS);
4064
4065	if (trans) {
 
4066		btrfs_end_transaction_throttle(trans, rc->extent_root);
4067		btrfs_btree_balance_dirty(rc->extent_root);
4068	}
4069
4070	if (!err) {
4071		ret = relocate_file_extent_cluster(rc->data_inode,
4072						   &rc->cluster);
4073		if (ret < 0)
4074			err = ret;
4075	}
4076
4077	rc->create_reloc_tree = 0;
4078	set_reloc_control(rc);
4079
4080	backref_cache_cleanup(&rc->backref_cache);
4081	btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4082
4083	err = prepare_to_merge(rc, err);
4084
4085	merge_reloc_roots(rc);
4086
4087	rc->merge_reloc_tree = 0;
4088	unset_reloc_control(rc);
4089	btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4090
4091	/* get rid of pinned extents */
4092	trans = btrfs_join_transaction(rc->extent_root);
4093	if (IS_ERR(trans))
4094		err = PTR_ERR(trans);
4095	else
4096		btrfs_commit_transaction(trans, rc->extent_root);
4097out_free:
4098	btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
4099	btrfs_free_path(path);
4100	return err;
4101}
4102
4103static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4104				 struct btrfs_root *root, u64 objectid)
4105{
4106	struct btrfs_path *path;
4107	struct btrfs_inode_item *item;
4108	struct extent_buffer *leaf;
4109	int ret;
4110
4111	path = btrfs_alloc_path();
4112	if (!path)
4113		return -ENOMEM;
4114
4115	ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4116	if (ret)
4117		goto out;
4118
4119	leaf = path->nodes[0];
4120	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4121	memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
4122	btrfs_set_inode_generation(leaf, item, 1);
4123	btrfs_set_inode_size(leaf, item, 0);
4124	btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4125	btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4126					  BTRFS_INODE_PREALLOC);
4127	btrfs_mark_buffer_dirty(leaf);
 
4128out:
4129	btrfs_free_path(path);
4130	return ret;
4131}
4132
4133/*
4134 * helper to create inode for data relocation.
4135 * the inode is in data relocation tree and its link count is 0
4136 */
4137static noinline_for_stack
4138struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4139				 struct btrfs_block_group_cache *group)
4140{
4141	struct inode *inode = NULL;
4142	struct btrfs_trans_handle *trans;
4143	struct btrfs_root *root;
4144	struct btrfs_key key;
4145	u64 objectid;
 
4146	int err = 0;
4147
4148	root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4149	if (IS_ERR(root))
4150		return ERR_CAST(root);
4151
4152	trans = btrfs_start_transaction(root, 6);
4153	if (IS_ERR(trans))
4154		return ERR_CAST(trans);
4155
4156	err = btrfs_find_free_objectid(root, &objectid);
4157	if (err)
4158		goto out;
4159
4160	err = __insert_orphan_inode(trans, root, objectid);
4161	BUG_ON(err);
4162
4163	key.objectid = objectid;
4164	key.type = BTRFS_INODE_ITEM_KEY;
4165	key.offset = 0;
4166	inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
4167	BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
4168	BTRFS_I(inode)->index_cnt = group->key.objectid;
4169
4170	err = btrfs_orphan_add(trans, inode);
4171out:
 
4172	btrfs_end_transaction(trans, root);
4173	btrfs_btree_balance_dirty(root);
4174	if (err) {
4175		if (inode)
4176			iput(inode);
4177		inode = ERR_PTR(err);
4178	}
4179	return inode;
4180}
4181
4182static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
4183{
4184	struct reloc_control *rc;
4185
4186	rc = kzalloc(sizeof(*rc), GFP_NOFS);
4187	if (!rc)
4188		return NULL;
4189
4190	INIT_LIST_HEAD(&rc->reloc_roots);
4191	backref_cache_init(&rc->backref_cache);
4192	mapping_tree_init(&rc->reloc_root_tree);
4193	extent_io_tree_init(&rc->processed_blocks,
4194			    fs_info->btree_inode->i_mapping);
4195	return rc;
4196}
4197
4198/*
4199 * function to relocate all extents in a block group.
4200 */
4201int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
4202{
4203	struct btrfs_fs_info *fs_info = extent_root->fs_info;
4204	struct reloc_control *rc;
4205	struct inode *inode;
4206	struct btrfs_path *path;
4207	int ret;
4208	int rw = 0;
4209	int err = 0;
4210
4211	rc = alloc_reloc_control(fs_info);
4212	if (!rc)
4213		return -ENOMEM;
4214
4215	rc->extent_root = extent_root;
4216
4217	rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4218	BUG_ON(!rc->block_group);
4219
4220	ret = btrfs_inc_block_group_ro(extent_root, rc->block_group);
4221	if (ret) {
4222		err = ret;
4223		goto out;
 
 
 
4224	}
4225	rw = 1;
4226
4227	path = btrfs_alloc_path();
4228	if (!path) {
4229		err = -ENOMEM;
4230		goto out;
4231	}
4232
4233	inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4234					path);
4235	btrfs_free_path(path);
4236
4237	if (!IS_ERR(inode))
4238		ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
4239	else
4240		ret = PTR_ERR(inode);
4241
4242	if (ret && ret != -ENOENT) {
4243		err = ret;
4244		goto out;
4245	}
4246
4247	rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4248	if (IS_ERR(rc->data_inode)) {
4249		err = PTR_ERR(rc->data_inode);
4250		rc->data_inode = NULL;
4251		goto out;
4252	}
4253
4254	btrfs_info(extent_root->fs_info, "relocating block group %llu flags %llu",
4255	       rc->block_group->key.objectid, rc->block_group->flags);
 
4256
4257	ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
4258	if (ret < 0) {
4259		err = ret;
4260		goto out;
4261	}
4262	btrfs_wait_ordered_roots(fs_info, -1);
4263
4264	while (1) {
4265		mutex_lock(&fs_info->cleaner_mutex);
 
 
4266		ret = relocate_block_group(rc);
 
4267		mutex_unlock(&fs_info->cleaner_mutex);
4268		if (ret < 0) {
4269			err = ret;
4270			goto out;
4271		}
4272
4273		if (rc->extents_found == 0)
4274			break;
4275
4276		btrfs_info(extent_root->fs_info, "found %llu extents",
4277			rc->extents_found);
4278
4279		if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4280			ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4281						       (u64)-1);
4282			if (ret) {
4283				err = ret;
4284				goto out;
4285			}
4286			invalidate_mapping_pages(rc->data_inode->i_mapping,
4287						 0, -1);
4288			rc->stage = UPDATE_DATA_PTRS;
4289		}
4290	}
4291
 
 
 
 
 
4292	WARN_ON(rc->block_group->pinned > 0);
4293	WARN_ON(rc->block_group->reserved > 0);
4294	WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4295out:
4296	if (err && rw)
4297		btrfs_dec_block_group_ro(extent_root, rc->block_group);
4298	iput(rc->data_inode);
4299	btrfs_put_block_group(rc->block_group);
4300	kfree(rc);
4301	return err;
4302}
4303
4304static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4305{
4306	struct btrfs_trans_handle *trans;
4307	int ret, err;
4308
4309	trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4310	if (IS_ERR(trans))
4311		return PTR_ERR(trans);
4312
4313	memset(&root->root_item.drop_progress, 0,
4314		sizeof(root->root_item.drop_progress));
4315	root->root_item.drop_level = 0;
4316	btrfs_set_root_refs(&root->root_item, 0);
4317	ret = btrfs_update_root(trans, root->fs_info->tree_root,
4318				&root->root_key, &root->root_item);
 
4319
4320	err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4321	if (err)
4322		return err;
4323	return ret;
4324}
4325
4326/*
4327 * recover relocation interrupted by system crash.
4328 *
4329 * this function resumes merging reloc trees with corresponding fs trees.
4330 * this is important for keeping the sharing of tree blocks
4331 */
4332int btrfs_recover_relocation(struct btrfs_root *root)
4333{
4334	LIST_HEAD(reloc_roots);
4335	struct btrfs_key key;
4336	struct btrfs_root *fs_root;
4337	struct btrfs_root *reloc_root;
4338	struct btrfs_path *path;
4339	struct extent_buffer *leaf;
4340	struct reloc_control *rc = NULL;
4341	struct btrfs_trans_handle *trans;
4342	int ret;
4343	int err = 0;
4344
4345	path = btrfs_alloc_path();
4346	if (!path)
4347		return -ENOMEM;
4348	path->reada = READA_BACK;
4349
4350	key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4351	key.type = BTRFS_ROOT_ITEM_KEY;
4352	key.offset = (u64)-1;
4353
4354	while (1) {
4355		ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4356					path, 0, 0);
4357		if (ret < 0) {
4358			err = ret;
4359			goto out;
4360		}
4361		if (ret > 0) {
4362			if (path->slots[0] == 0)
4363				break;
4364			path->slots[0]--;
4365		}
4366		leaf = path->nodes[0];
4367		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4368		btrfs_release_path(path);
4369
4370		if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4371		    key.type != BTRFS_ROOT_ITEM_KEY)
4372			break;
4373
4374		reloc_root = btrfs_read_fs_root(root, &key);
4375		if (IS_ERR(reloc_root)) {
4376			err = PTR_ERR(reloc_root);
4377			goto out;
4378		}
4379
4380		list_add(&reloc_root->root_list, &reloc_roots);
4381
4382		if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4383			fs_root = read_fs_root(root->fs_info,
4384					       reloc_root->root_key.offset);
4385			if (IS_ERR(fs_root)) {
4386				ret = PTR_ERR(fs_root);
4387				if (ret != -ENOENT) {
4388					err = ret;
4389					goto out;
4390				}
4391				ret = mark_garbage_root(reloc_root);
4392				if (ret < 0) {
4393					err = ret;
4394					goto out;
4395				}
4396			}
4397		}
4398
4399		if (key.offset == 0)
4400			break;
4401
4402		key.offset--;
4403	}
4404	btrfs_release_path(path);
4405
4406	if (list_empty(&reloc_roots))
4407		goto out;
4408
4409	rc = alloc_reloc_control(root->fs_info);
4410	if (!rc) {
4411		err = -ENOMEM;
4412		goto out;
4413	}
4414
4415	rc->extent_root = root->fs_info->extent_root;
4416
4417	set_reloc_control(rc);
4418
4419	trans = btrfs_join_transaction(rc->extent_root);
4420	if (IS_ERR(trans)) {
4421		unset_reloc_control(rc);
4422		err = PTR_ERR(trans);
4423		goto out_free;
4424	}
4425
4426	rc->merge_reloc_tree = 1;
4427
4428	while (!list_empty(&reloc_roots)) {
4429		reloc_root = list_entry(reloc_roots.next,
4430					struct btrfs_root, root_list);
4431		list_del(&reloc_root->root_list);
4432
4433		if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4434			list_add_tail(&reloc_root->root_list,
4435				      &rc->reloc_roots);
4436			continue;
4437		}
4438
4439		fs_root = read_fs_root(root->fs_info,
4440				       reloc_root->root_key.offset);
4441		if (IS_ERR(fs_root)) {
4442			err = PTR_ERR(fs_root);
4443			goto out_free;
4444		}
4445
4446		err = __add_reloc_root(reloc_root);
4447		BUG_ON(err < 0); /* -ENOMEM or logic error */
4448		fs_root->reloc_root = reloc_root;
4449	}
4450
4451	err = btrfs_commit_transaction(trans, rc->extent_root);
4452	if (err)
4453		goto out_free;
4454
4455	merge_reloc_roots(rc);
4456
4457	unset_reloc_control(rc);
4458
4459	trans = btrfs_join_transaction(rc->extent_root);
4460	if (IS_ERR(trans))
4461		err = PTR_ERR(trans);
4462	else
4463		err = btrfs_commit_transaction(trans, rc->extent_root);
4464out_free:
4465	kfree(rc);
4466out:
4467	if (!list_empty(&reloc_roots))
4468		free_reloc_roots(&reloc_roots);
4469
 
 
 
 
 
4470	btrfs_free_path(path);
4471
4472	if (err == 0) {
4473		/* cleanup orphan inode in data relocation tree */
4474		fs_root = read_fs_root(root->fs_info,
4475				       BTRFS_DATA_RELOC_TREE_OBJECTID);
4476		if (IS_ERR(fs_root))
4477			err = PTR_ERR(fs_root);
4478		else
4479			err = btrfs_orphan_cleanup(fs_root);
4480	}
4481	return err;
4482}
4483
4484/*
4485 * helper to add ordered checksum for data relocation.
4486 *
4487 * cloning checksum properly handles the nodatasum extents.
4488 * it also saves CPU time to re-calculate the checksum.
4489 */
4490int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4491{
4492	struct btrfs_ordered_sum *sums;
 
4493	struct btrfs_ordered_extent *ordered;
4494	struct btrfs_root *root = BTRFS_I(inode)->root;
 
4495	int ret;
4496	u64 disk_bytenr;
4497	u64 new_bytenr;
4498	LIST_HEAD(list);
4499
4500	ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4501	BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4502
4503	disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4504	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4505				       disk_bytenr + len - 1, &list, 0);
4506	if (ret)
4507		goto out;
4508
4509	while (!list_empty(&list)) {
4510		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4511		list_del_init(&sums->list);
4512
4513		/*
4514		 * We need to offset the new_bytenr based on where the csum is.
4515		 * We need to do this because we will read in entire prealloc
4516		 * extents but we may have written to say the middle of the
4517		 * prealloc extent, so we need to make sure the csum goes with
4518		 * the right disk offset.
4519		 *
4520		 * We can do this because the data reloc inode refers strictly
4521		 * to the on disk bytes, so we don't have to worry about
4522		 * disk_len vs real len like with real inodes since it's all
4523		 * disk length.
4524		 */
4525		new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4526		sums->bytenr = new_bytenr;
4527
4528		btrfs_add_ordered_sum(inode, ordered, sums);
4529	}
4530out:
4531	btrfs_put_ordered_extent(ordered);
4532	return ret;
4533}
4534
4535int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4536			  struct btrfs_root *root, struct extent_buffer *buf,
4537			  struct extent_buffer *cow)
4538{
4539	struct reloc_control *rc;
4540	struct backref_node *node;
4541	int first_cow = 0;
4542	int level;
4543	int ret = 0;
4544
4545	rc = root->fs_info->reloc_ctl;
4546	if (!rc)
4547		return 0;
4548
4549	BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4550	       root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4551
4552	if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
4553		if (buf == root->node)
4554			__update_reloc_root(root, cow->start);
4555	}
4556
4557	level = btrfs_header_level(buf);
4558	if (btrfs_header_generation(buf) <=
4559	    btrfs_root_last_snapshot(&root->root_item))
4560		first_cow = 1;
4561
4562	if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4563	    rc->create_reloc_tree) {
4564		WARN_ON(!first_cow && level == 0);
4565
4566		node = rc->backref_cache.path[level];
4567		BUG_ON(node->bytenr != buf->start &&
4568		       node->new_bytenr != buf->start);
4569
4570		drop_node_buffer(node);
4571		extent_buffer_get(cow);
4572		node->eb = cow;
4573		node->new_bytenr = cow->start;
4574
4575		if (!node->pending) {
4576			list_move_tail(&node->list,
4577				       &rc->backref_cache.pending[level]);
4578			node->pending = 1;
4579		}
4580
4581		if (first_cow)
4582			__mark_block_processed(rc, node);
4583
4584		if (first_cow && level > 0)
4585			rc->nodes_relocated += buf->len;
4586	}
4587
4588	if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4589		ret = replace_file_extents(trans, rc, root, cow);
4590	return ret;
 
4591}
4592
4593/*
4594 * called before creating snapshot. it calculates metadata reservation
4595 * requried for relocating tree blocks in the snapshot
4596 */
4597void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,
 
4598			      u64 *bytes_to_reserve)
4599{
4600	struct btrfs_root *root;
4601	struct reloc_control *rc;
4602
4603	root = pending->root;
4604	if (!root->reloc_root)
4605		return;
4606
4607	rc = root->fs_info->reloc_ctl;
4608	if (!rc->merge_reloc_tree)
4609		return;
4610
4611	root = root->reloc_root;
4612	BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4613	/*
4614	 * relocation is in the stage of merging trees. the space
4615	 * used by merging a reloc tree is twice the size of
4616	 * relocated tree nodes in the worst case. half for cowing
4617	 * the reloc tree, half for cowing the fs tree. the space
4618	 * used by cowing the reloc tree will be freed after the
4619	 * tree is dropped. if we create snapshot, cowing the fs
4620	 * tree may use more space than it frees. so we need
4621	 * reserve extra space.
4622	 */
4623	*bytes_to_reserve += rc->nodes_relocated;
4624}
4625
4626/*
4627 * called after snapshot is created. migrate block reservation
4628 * and create reloc root for the newly created snapshot
4629 */
4630int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4631			       struct btrfs_pending_snapshot *pending)
4632{
4633	struct btrfs_root *root = pending->root;
4634	struct btrfs_root *reloc_root;
4635	struct btrfs_root *new_root;
4636	struct reloc_control *rc;
4637	int ret;
4638
4639	if (!root->reloc_root)
4640		return 0;
4641
4642	rc = root->fs_info->reloc_ctl;
4643	rc->merging_rsv_size += rc->nodes_relocated;
4644
4645	if (rc->merge_reloc_tree) {
4646		ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4647					      rc->block_rsv,
4648					      rc->nodes_relocated);
4649		if (ret)
4650			return ret;
4651	}
4652
4653	new_root = pending->snap;
4654	reloc_root = create_reloc_root(trans, root->reloc_root,
4655				       new_root->root_key.objectid);
4656	if (IS_ERR(reloc_root))
4657		return PTR_ERR(reloc_root);
4658
4659	ret = __add_reloc_root(reloc_root);
4660	BUG_ON(ret < 0);
4661	new_root->reloc_root = reloc_root;
4662
4663	if (rc->create_reloc_tree)
4664		ret = clone_backref_node(trans, rc, root, reloc_root);
4665	return ret;
 
4666}