1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2007,2008 Oracle.  All rights reserved.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   4 */
   5
   6#include <linux/sched.h>
   7#include <linux/slab.h>
   8#include <linux/rbtree.h>
   9#include <linux/mm.h>
  10#include "ctree.h"
  11#include "disk-io.h"
  12#include "transaction.h"
  13#include "print-tree.h"
  14#include "locking.h"
  15#include "volumes.h"
  16#include "qgroup.h"
  17
  18static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  19		      *root, struct btrfs_path *path, int level);
  20static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  21		      const struct btrfs_key *ins_key, struct btrfs_path *path,
  22		      int data_size, int extend);
  23static int push_node_left(struct btrfs_trans_handle *trans,
  24			  struct extent_buffer *dst,
  25			  struct extent_buffer *src, int empty);
  26static int balance_node_right(struct btrfs_trans_handle *trans,
 
  27			      struct extent_buffer *dst_buf,
  28			      struct extent_buffer *src_buf);
  29static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
  30		    int level, int slot);
  31
  32static const struct btrfs_csums {
  33	u16		size;
  34	const char	*name;
  35} btrfs_csums[] = {
  36	[BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
  37};
  38
  39int btrfs_super_csum_size(const struct btrfs_super_block *s)
  40{
  41	u16 t = btrfs_super_csum_type(s);
  42	/*
  43	 * csum type is validated at mount time
  44	 */
  45	return btrfs_csums[t].size;
  46}
  47
  48const char *btrfs_super_csum_name(u16 csum_type)
  49{
  50	/* csum type is validated at mount time */
  51	return btrfs_csums[csum_type].name;
  52}
  53
  54struct btrfs_path *btrfs_alloc_path(void)
  55{
  56	return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
 
 
  57}
  58
  59/*
  60 * set all locked nodes in the path to blocking locks.  This should
  61 * be done before scheduling
  62 */
  63noinline void btrfs_set_path_blocking(struct btrfs_path *p)
  64{
  65	int i;
  66	for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  67		if (!p->nodes[i] || !p->locks[i])
  68			continue;
  69		/*
  70		 * If we currently have a spinning reader or writer lock this
  71		 * will bump the count of blocking holders and drop the
  72		 * spinlock.
  73		 */
  74		if (p->locks[i] == BTRFS_READ_LOCK) {
  75			btrfs_set_lock_blocking_read(p->nodes[i]);
  76			p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
  77		} else if (p->locks[i] == BTRFS_WRITE_LOCK) {
  78			btrfs_set_lock_blocking_write(p->nodes[i]);
  79			p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  80		}
  81	}
 
 
 
  82}
  83
  84/* this also releases the path */
  85void btrfs_free_path(struct btrfs_path *p)
  86{
  87	if (!p)
  88		return;
  89	btrfs_release_path(p);
  90	kmem_cache_free(btrfs_path_cachep, p);
  91}
  92
  93/*
  94 * path release drops references on the extent buffers in the path
  95 * and it drops any locks held by this path
  96 *
  97 * It is safe to call this on paths that no locks or extent buffers held.
  98 */
  99noinline void btrfs_release_path(struct btrfs_path *p)
 100{
 101	int i;
 102
 103	for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
 104		p->slots[i] = 0;
 105		if (!p->nodes[i])
 106			continue;
 107		if (p->locks[i]) {
 108			btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
 109			p->locks[i] = 0;
 110		}
 111		free_extent_buffer(p->nodes[i]);
 112		p->nodes[i] = NULL;
 113	}
 114}
 115
 116/*
 117 * safely gets a reference on the root node of a tree.  A lock
 118 * is not taken, so a concurrent writer may put a different node
 119 * at the root of the tree.  See btrfs_lock_root_node for the
 120 * looping required.
 121 *
 122 * The extent buffer returned by this has a reference taken, so
 123 * it won't disappear.  It may stop being the root of the tree
 124 * at any time because there are no locks held.
 125 */
 126struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
 127{
 128	struct extent_buffer *eb;
 129
 130	while (1) {
 131		rcu_read_lock();
 132		eb = rcu_dereference(root->node);
 133
 134		/*
 135		 * RCU really hurts here, we could free up the root node because
 136		 * it was COWed but we may not get the new root node yet so do
 137		 * the inc_not_zero dance and if it doesn't work then
 138		 * synchronize_rcu and try again.
 139		 */
 140		if (atomic_inc_not_zero(&eb->refs)) {
 141			rcu_read_unlock();
 142			break;
 143		}
 144		rcu_read_unlock();
 145		synchronize_rcu();
 146	}
 147	return eb;
 148}
 149
 150/* loop around taking references on and locking the root node of the
 151 * tree until you end up with a lock on the root.  A locked buffer
 152 * is returned, with a reference held.
 153 */
 154struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
 155{
 156	struct extent_buffer *eb;
 157
 158	while (1) {
 159		eb = btrfs_root_node(root);
 160		btrfs_tree_lock(eb);
 161		if (eb == root->node)
 162			break;
 163		btrfs_tree_unlock(eb);
 164		free_extent_buffer(eb);
 165	}
 166	return eb;
 167}
 168
 169/* loop around taking references on and locking the root node of the
 170 * tree until you end up with a lock on the root.  A locked buffer
 171 * is returned, with a reference held.
 172 */
 173struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
 174{
 175	struct extent_buffer *eb;
 176
 177	while (1) {
 178		eb = btrfs_root_node(root);
 179		btrfs_tree_read_lock(eb);
 180		if (eb == root->node)
 181			break;
 182		btrfs_tree_read_unlock(eb);
 183		free_extent_buffer(eb);
 184	}
 185	return eb;
 186}
 187
 188/* cowonly root (everything not a reference counted cow subvolume), just get
 189 * put onto a simple dirty list.  transaction.c walks this to make sure they
 190 * get properly updated on disk.
 191 */
 192static void add_root_to_dirty_list(struct btrfs_root *root)
 193{
 194	struct btrfs_fs_info *fs_info = root->fs_info;
 195
 196	if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
 197	    !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
 198		return;
 199
 200	spin_lock(&fs_info->trans_lock);
 201	if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
 202		/* Want the extent tree to be the last on the list */
 203		if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
 204			list_move_tail(&root->dirty_list,
 205				       &fs_info->dirty_cowonly_roots);
 206		else
 207			list_move(&root->dirty_list,
 208				  &fs_info->dirty_cowonly_roots);
 209	}
 210	spin_unlock(&fs_info->trans_lock);
 211}
 212
 213/*
 214 * used by snapshot creation to make a copy of a root for a tree with
 215 * a given objectid.  The buffer with the new root node is returned in
 216 * cow_ret, and this func returns zero on success or a negative error code.
 217 */
 218int btrfs_copy_root(struct btrfs_trans_handle *trans,
 219		      struct btrfs_root *root,
 220		      struct extent_buffer *buf,
 221		      struct extent_buffer **cow_ret, u64 new_root_objectid)
 222{
 223	struct btrfs_fs_info *fs_info = root->fs_info;
 224	struct extent_buffer *cow;
 225	int ret = 0;
 226	int level;
 227	struct btrfs_disk_key disk_key;
 228
 229	WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 230		trans->transid != fs_info->running_transaction->transid);
 231	WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 232		trans->transid != root->last_trans);
 233
 234	level = btrfs_header_level(buf);
 235	if (level == 0)
 236		btrfs_item_key(buf, &disk_key, 0);
 237	else
 238		btrfs_node_key(buf, &disk_key, 0);
 239
 240	cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
 241			&disk_key, level, buf->start, 0);
 242	if (IS_ERR(cow))
 243		return PTR_ERR(cow);
 244
 245	copy_extent_buffer_full(cow, buf);
 246	btrfs_set_header_bytenr(cow, cow->start);
 247	btrfs_set_header_generation(cow, trans->transid);
 248	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 249	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 250				     BTRFS_HEADER_FLAG_RELOC);
 251	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 252		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 253	else
 254		btrfs_set_header_owner(cow, new_root_objectid);
 255
 256	write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
 
 257
 258	WARN_ON(btrfs_header_generation(buf) > trans->transid);
 259	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 260		ret = btrfs_inc_ref(trans, root, cow, 1);
 261	else
 262		ret = btrfs_inc_ref(trans, root, cow, 0);
 263
 264	if (ret)
 265		return ret;
 266
 267	btrfs_mark_buffer_dirty(cow);
 268	*cow_ret = cow;
 269	return 0;
 270}
 271
 272enum mod_log_op {
 273	MOD_LOG_KEY_REPLACE,
 274	MOD_LOG_KEY_ADD,
 275	MOD_LOG_KEY_REMOVE,
 276	MOD_LOG_KEY_REMOVE_WHILE_FREEING,
 277	MOD_LOG_KEY_REMOVE_WHILE_MOVING,
 278	MOD_LOG_MOVE_KEYS,
 279	MOD_LOG_ROOT_REPLACE,
 280};
 281
 
 
 
 
 
 282struct tree_mod_root {
 283	u64 logical;
 284	u8 level;
 285};
 286
 287struct tree_mod_elem {
 288	struct rb_node node;
 289	u64 logical;
 290	u64 seq;
 291	enum mod_log_op op;
 292
 293	/* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
 294	int slot;
 295
 296	/* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
 297	u64 generation;
 298
 299	/* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
 300	struct btrfs_disk_key key;
 301	u64 blockptr;
 302
 303	/* this is used for op == MOD_LOG_MOVE_KEYS */
 304	struct {
 305		int dst_slot;
 306		int nr_items;
 307	} move;
 308
 309	/* this is used for op == MOD_LOG_ROOT_REPLACE */
 310	struct tree_mod_root old_root;
 311};
 312
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 313/*
 314 * Pull a new tree mod seq number for our operation.
 315 */
 316static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
 317{
 318	return atomic64_inc_return(&fs_info->tree_mod_seq);
 319}
 320
 321/*
 322 * This adds a new blocker to the tree mod log's blocker list if the @elem
 323 * passed does not already have a sequence number set. So when a caller expects
 324 * to record tree modifications, it should ensure to set elem->seq to zero
 325 * before calling btrfs_get_tree_mod_seq.
 326 * Returns a fresh, unused tree log modification sequence number, even if no new
 327 * blocker was added.
 328 */
 329u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
 330			   struct seq_list *elem)
 331{
 332	write_lock(&fs_info->tree_mod_log_lock);
 333	spin_lock(&fs_info->tree_mod_seq_lock);
 334	if (!elem->seq) {
 335		elem->seq = btrfs_inc_tree_mod_seq(fs_info);
 336		list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
 337	}
 338	spin_unlock(&fs_info->tree_mod_seq_lock);
 339	write_unlock(&fs_info->tree_mod_log_lock);
 340
 341	return elem->seq;
 342}
 343
 344void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
 345			    struct seq_list *elem)
 346{
 347	struct rb_root *tm_root;
 348	struct rb_node *node;
 349	struct rb_node *next;
 350	struct seq_list *cur_elem;
 351	struct tree_mod_elem *tm;
 352	u64 min_seq = (u64)-1;
 353	u64 seq_putting = elem->seq;
 354
 355	if (!seq_putting)
 356		return;
 357
 358	spin_lock(&fs_info->tree_mod_seq_lock);
 359	list_del(&elem->list);
 360	elem->seq = 0;
 361
 362	list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
 363		if (cur_elem->seq < min_seq) {
 364			if (seq_putting > cur_elem->seq) {
 365				/*
 366				 * blocker with lower sequence number exists, we
 367				 * cannot remove anything from the log
 368				 */
 369				spin_unlock(&fs_info->tree_mod_seq_lock);
 370				return;
 371			}
 372			min_seq = cur_elem->seq;
 373		}
 374	}
 375	spin_unlock(&fs_info->tree_mod_seq_lock);
 376
 377	/*
 378	 * anything that's lower than the lowest existing (read: blocked)
 379	 * sequence number can be removed from the tree.
 380	 */
 381	write_lock(&fs_info->tree_mod_log_lock);
 382	tm_root = &fs_info->tree_mod_log;
 383	for (node = rb_first(tm_root); node; node = next) {
 384		next = rb_next(node);
 385		tm = rb_entry(node, struct tree_mod_elem, node);
 386		if (tm->seq > min_seq)
 387			continue;
 388		rb_erase(node, tm_root);
 389		kfree(tm);
 390	}
 391	write_unlock(&fs_info->tree_mod_log_lock);
 392}
 393
 394/*
 395 * key order of the log:
 396 *       node/leaf start address -> sequence
 397 *
 398 * The 'start address' is the logical address of the *new* root node
 399 * for root replace operations, or the logical address of the affected
 400 * block for all other operations.
 
 
 401 */
 402static noinline int
 403__tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
 404{
 405	struct rb_root *tm_root;
 406	struct rb_node **new;
 407	struct rb_node *parent = NULL;
 408	struct tree_mod_elem *cur;
 409
 410	lockdep_assert_held_write(&fs_info->tree_mod_log_lock);
 411
 412	tm->seq = btrfs_inc_tree_mod_seq(fs_info);
 413
 414	tm_root = &fs_info->tree_mod_log;
 415	new = &tm_root->rb_node;
 416	while (*new) {
 417		cur = rb_entry(*new, struct tree_mod_elem, node);
 418		parent = *new;
 419		if (cur->logical < tm->logical)
 420			new = &((*new)->rb_left);
 421		else if (cur->logical > tm->logical)
 422			new = &((*new)->rb_right);
 423		else if (cur->seq < tm->seq)
 424			new = &((*new)->rb_left);
 425		else if (cur->seq > tm->seq)
 426			new = &((*new)->rb_right);
 427		else
 428			return -EEXIST;
 429	}
 430
 431	rb_link_node(&tm->node, parent, new);
 432	rb_insert_color(&tm->node, tm_root);
 433	return 0;
 434}
 435
 436/*
 437 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
 438 * returns zero with the tree_mod_log_lock acquired. The caller must hold
 439 * this until all tree mod log insertions are recorded in the rb tree and then
 440 * write unlock fs_info::tree_mod_log_lock.
 441 */
 442static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
 443				    struct extent_buffer *eb) {
 444	smp_mb();
 445	if (list_empty(&(fs_info)->tree_mod_seq_list))
 446		return 1;
 447	if (eb && btrfs_header_level(eb) == 0)
 448		return 1;
 449
 450	write_lock(&fs_info->tree_mod_log_lock);
 451	if (list_empty(&(fs_info)->tree_mod_seq_list)) {
 452		write_unlock(&fs_info->tree_mod_log_lock);
 453		return 1;
 454	}
 455
 456	return 0;
 457}
 458
 459/* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
 460static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
 461				    struct extent_buffer *eb)
 462{
 463	smp_mb();
 464	if (list_empty(&(fs_info)->tree_mod_seq_list))
 465		return 0;
 466	if (eb && btrfs_header_level(eb) == 0)
 467		return 0;
 468
 469	return 1;
 470}
 471
 472static struct tree_mod_elem *
 473alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
 474		    enum mod_log_op op, gfp_t flags)
 475{
 476	struct tree_mod_elem *tm;
 477
 478	tm = kzalloc(sizeof(*tm), flags);
 479	if (!tm)
 480		return NULL;
 481
 482	tm->logical = eb->start;
 483	if (op != MOD_LOG_KEY_ADD) {
 484		btrfs_node_key(eb, &tm->key, slot);
 485		tm->blockptr = btrfs_node_blockptr(eb, slot);
 486	}
 487	tm->op = op;
 488	tm->slot = slot;
 489	tm->generation = btrfs_node_ptr_generation(eb, slot);
 490	RB_CLEAR_NODE(&tm->node);
 491
 492	return tm;
 493}
 494
 495static noinline int tree_mod_log_insert_key(struct extent_buffer *eb, int slot,
 496		enum mod_log_op op, gfp_t flags)
 
 
 497{
 498	struct tree_mod_elem *tm;
 499	int ret;
 500
 501	if (!tree_mod_need_log(eb->fs_info, eb))
 502		return 0;
 503
 504	tm = alloc_tree_mod_elem(eb, slot, op, flags);
 505	if (!tm)
 506		return -ENOMEM;
 507
 508	if (tree_mod_dont_log(eb->fs_info, eb)) {
 509		kfree(tm);
 510		return 0;
 511	}
 512
 513	ret = __tree_mod_log_insert(eb->fs_info, tm);
 514	write_unlock(&eb->fs_info->tree_mod_log_lock);
 515	if (ret)
 516		kfree(tm);
 517
 518	return ret;
 519}
 520
 521static noinline int tree_mod_log_insert_move(struct extent_buffer *eb,
 522		int dst_slot, int src_slot, int nr_items)
 
 
 523{
 524	struct tree_mod_elem *tm = NULL;
 525	struct tree_mod_elem **tm_list = NULL;
 526	int ret = 0;
 527	int i;
 528	int locked = 0;
 529
 530	if (!tree_mod_need_log(eb->fs_info, eb))
 531		return 0;
 532
 533	tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS);
 534	if (!tm_list)
 535		return -ENOMEM;
 536
 537	tm = kzalloc(sizeof(*tm), GFP_NOFS);
 538	if (!tm) {
 539		ret = -ENOMEM;
 540		goto free_tms;
 541	}
 542
 543	tm->logical = eb->start;
 544	tm->slot = src_slot;
 545	tm->move.dst_slot = dst_slot;
 546	tm->move.nr_items = nr_items;
 547	tm->op = MOD_LOG_MOVE_KEYS;
 548
 549	for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
 550		tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
 551		    MOD_LOG_KEY_REMOVE_WHILE_MOVING, GFP_NOFS);
 552		if (!tm_list[i]) {
 553			ret = -ENOMEM;
 554			goto free_tms;
 555		}
 556	}
 557
 558	if (tree_mod_dont_log(eb->fs_info, eb))
 559		goto free_tms;
 560	locked = 1;
 561
 562	/*
 563	 * When we override something during the move, we log these removals.
 564	 * This can only happen when we move towards the beginning of the
 565	 * buffer, i.e. dst_slot < src_slot.
 566	 */
 567	for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
 568		ret = __tree_mod_log_insert(eb->fs_info, tm_list[i]);
 569		if (ret)
 570			goto free_tms;
 571	}
 572
 573	ret = __tree_mod_log_insert(eb->fs_info, tm);
 574	if (ret)
 575		goto free_tms;
 576	write_unlock(&eb->fs_info->tree_mod_log_lock);
 577	kfree(tm_list);
 578
 579	return 0;
 580free_tms:
 581	for (i = 0; i < nr_items; i++) {
 582		if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
 583			rb_erase(&tm_list[i]->node, &eb->fs_info->tree_mod_log);
 584		kfree(tm_list[i]);
 585	}
 586	if (locked)
 587		write_unlock(&eb->fs_info->tree_mod_log_lock);
 588	kfree(tm_list);
 589	kfree(tm);
 590
 591	return ret;
 592}
 593
 594static inline int
 595__tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
 596		       struct tree_mod_elem **tm_list,
 597		       int nritems)
 598{
 599	int i, j;
 600	int ret;
 601
 602	for (i = nritems - 1; i >= 0; i--) {
 603		ret = __tree_mod_log_insert(fs_info, tm_list[i]);
 604		if (ret) {
 605			for (j = nritems - 1; j > i; j--)
 606				rb_erase(&tm_list[j]->node,
 607					 &fs_info->tree_mod_log);
 608			return ret;
 609		}
 610	}
 611
 612	return 0;
 613}
 614
 615static noinline int tree_mod_log_insert_root(struct extent_buffer *old_root,
 616			 struct extent_buffer *new_root, int log_removal)
 
 
 
 617{
 618	struct btrfs_fs_info *fs_info = old_root->fs_info;
 619	struct tree_mod_elem *tm = NULL;
 620	struct tree_mod_elem **tm_list = NULL;
 621	int nritems = 0;
 622	int ret = 0;
 623	int i;
 624
 625	if (!tree_mod_need_log(fs_info, NULL))
 626		return 0;
 627
 628	if (log_removal && btrfs_header_level(old_root) > 0) {
 629		nritems = btrfs_header_nritems(old_root);
 630		tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *),
 631				  GFP_NOFS);
 632		if (!tm_list) {
 633			ret = -ENOMEM;
 634			goto free_tms;
 635		}
 636		for (i = 0; i < nritems; i++) {
 637			tm_list[i] = alloc_tree_mod_elem(old_root, i,
 638			    MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
 639			if (!tm_list[i]) {
 640				ret = -ENOMEM;
 641				goto free_tms;
 642			}
 643		}
 644	}
 645
 646	tm = kzalloc(sizeof(*tm), GFP_NOFS);
 647	if (!tm) {
 648		ret = -ENOMEM;
 649		goto free_tms;
 650	}
 651
 652	tm->logical = new_root->start;
 653	tm->old_root.logical = old_root->start;
 654	tm->old_root.level = btrfs_header_level(old_root);
 655	tm->generation = btrfs_header_generation(old_root);
 656	tm->op = MOD_LOG_ROOT_REPLACE;
 657
 658	if (tree_mod_dont_log(fs_info, NULL))
 659		goto free_tms;
 660
 661	if (tm_list)
 662		ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
 663	if (!ret)
 664		ret = __tree_mod_log_insert(fs_info, tm);
 665
 666	write_unlock(&fs_info->tree_mod_log_lock);
 667	if (ret)
 668		goto free_tms;
 669	kfree(tm_list);
 670
 671	return ret;
 672
 673free_tms:
 674	if (tm_list) {
 675		for (i = 0; i < nritems; i++)
 676			kfree(tm_list[i]);
 677		kfree(tm_list);
 678	}
 679	kfree(tm);
 680
 681	return ret;
 682}
 683
 684static struct tree_mod_elem *
 685__tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
 686		      int smallest)
 687{
 688	struct rb_root *tm_root;
 689	struct rb_node *node;
 690	struct tree_mod_elem *cur = NULL;
 691	struct tree_mod_elem *found = NULL;
 692
 693	read_lock(&fs_info->tree_mod_log_lock);
 694	tm_root = &fs_info->tree_mod_log;
 695	node = tm_root->rb_node;
 696	while (node) {
 697		cur = rb_entry(node, struct tree_mod_elem, node);
 698		if (cur->logical < start) {
 699			node = node->rb_left;
 700		} else if (cur->logical > start) {
 701			node = node->rb_right;
 702		} else if (cur->seq < min_seq) {
 703			node = node->rb_left;
 704		} else if (!smallest) {
 705			/* we want the node with the highest seq */
 706			if (found)
 707				BUG_ON(found->seq > cur->seq);
 708			found = cur;
 709			node = node->rb_left;
 710		} else if (cur->seq > min_seq) {
 711			/* we want the node with the smallest seq */
 712			if (found)
 713				BUG_ON(found->seq < cur->seq);
 714			found = cur;
 715			node = node->rb_right;
 716		} else {
 717			found = cur;
 718			break;
 719		}
 720	}
 721	read_unlock(&fs_info->tree_mod_log_lock);
 722
 723	return found;
 724}
 725
 726/*
 727 * this returns the element from the log with the smallest time sequence
 728 * value that's in the log (the oldest log item). any element with a time
 729 * sequence lower than min_seq will be ignored.
 730 */
 731static struct tree_mod_elem *
 732tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
 733			   u64 min_seq)
 734{
 735	return __tree_mod_log_search(fs_info, start, min_seq, 1);
 736}
 737
 738/*
 739 * this returns the element from the log with the largest time sequence
 740 * value that's in the log (the most recent log item). any element with
 741 * a time sequence lower than min_seq will be ignored.
 742 */
 743static struct tree_mod_elem *
 744tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
 745{
 746	return __tree_mod_log_search(fs_info, start, min_seq, 0);
 747}
 748
 749static noinline int tree_mod_log_eb_copy(struct extent_buffer *dst,
 
 750		     struct extent_buffer *src, unsigned long dst_offset,
 751		     unsigned long src_offset, int nr_items)
 752{
 753	struct btrfs_fs_info *fs_info = dst->fs_info;
 754	int ret = 0;
 755	struct tree_mod_elem **tm_list = NULL;
 756	struct tree_mod_elem **tm_list_add, **tm_list_rem;
 757	int i;
 758	int locked = 0;
 759
 760	if (!tree_mod_need_log(fs_info, NULL))
 761		return 0;
 762
 763	if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
 764		return 0;
 765
 766	tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *),
 767			  GFP_NOFS);
 768	if (!tm_list)
 769		return -ENOMEM;
 770
 771	tm_list_add = tm_list;
 772	tm_list_rem = tm_list + nr_items;
 773	for (i = 0; i < nr_items; i++) {
 774		tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
 775		    MOD_LOG_KEY_REMOVE, GFP_NOFS);
 776		if (!tm_list_rem[i]) {
 777			ret = -ENOMEM;
 778			goto free_tms;
 779		}
 780
 781		tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
 782		    MOD_LOG_KEY_ADD, GFP_NOFS);
 783		if (!tm_list_add[i]) {
 784			ret = -ENOMEM;
 785			goto free_tms;
 786		}
 787	}
 788
 789	if (tree_mod_dont_log(fs_info, NULL))
 790		goto free_tms;
 791	locked = 1;
 792
 793	for (i = 0; i < nr_items; i++) {
 794		ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
 795		if (ret)
 796			goto free_tms;
 797		ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
 798		if (ret)
 799			goto free_tms;
 800	}
 801
 802	write_unlock(&fs_info->tree_mod_log_lock);
 803	kfree(tm_list);
 804
 805	return 0;
 806
 807free_tms:
 808	for (i = 0; i < nr_items * 2; i++) {
 809		if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
 810			rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
 811		kfree(tm_list[i]);
 812	}
 813	if (locked)
 814		write_unlock(&fs_info->tree_mod_log_lock);
 815	kfree(tm_list);
 816
 817	return ret;
 818}
 819
 820static noinline int tree_mod_log_free_eb(struct extent_buffer *eb)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 821{
 822	struct tree_mod_elem **tm_list = NULL;
 823	int nritems = 0;
 824	int i;
 825	int ret = 0;
 826
 827	if (btrfs_header_level(eb) == 0)
 828		return 0;
 829
 830	if (!tree_mod_need_log(eb->fs_info, NULL))
 831		return 0;
 832
 833	nritems = btrfs_header_nritems(eb);
 834	tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS);
 835	if (!tm_list)
 836		return -ENOMEM;
 837
 838	for (i = 0; i < nritems; i++) {
 839		tm_list[i] = alloc_tree_mod_elem(eb, i,
 840		    MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
 841		if (!tm_list[i]) {
 842			ret = -ENOMEM;
 843			goto free_tms;
 844		}
 845	}
 846
 847	if (tree_mod_dont_log(eb->fs_info, eb))
 848		goto free_tms;
 849
 850	ret = __tree_mod_log_free_eb(eb->fs_info, tm_list, nritems);
 851	write_unlock(&eb->fs_info->tree_mod_log_lock);
 852	if (ret)
 853		goto free_tms;
 854	kfree(tm_list);
 855
 856	return 0;
 857
 858free_tms:
 859	for (i = 0; i < nritems; i++)
 860		kfree(tm_list[i]);
 861	kfree(tm_list);
 862
 863	return ret;
 864}
 865
 
 
 
 
 
 
 
 
 
 
 
 866/*
 867 * check if the tree block can be shared by multiple trees
 868 */
 869int btrfs_block_can_be_shared(struct btrfs_root *root,
 870			      struct extent_buffer *buf)
 871{
 872	/*
 873	 * Tree blocks not in reference counted trees and tree roots
 874	 * are never shared. If a block was allocated after the last
 875	 * snapshot and the block was not allocated by tree relocation,
 876	 * we know the block is not shared.
 877	 */
 878	if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 879	    buf != root->node && buf != root->commit_root &&
 880	    (btrfs_header_generation(buf) <=
 881	     btrfs_root_last_snapshot(&root->root_item) ||
 882	     btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 883		return 1;
 884
 
 
 
 
 885	return 0;
 886}
 887
 888static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 889				       struct btrfs_root *root,
 890				       struct extent_buffer *buf,
 891				       struct extent_buffer *cow,
 892				       int *last_ref)
 893{
 894	struct btrfs_fs_info *fs_info = root->fs_info;
 895	u64 refs;
 896	u64 owner;
 897	u64 flags;
 898	u64 new_flags = 0;
 899	int ret;
 900
 901	/*
 902	 * Backrefs update rules:
 903	 *
 904	 * Always use full backrefs for extent pointers in tree block
 905	 * allocated by tree relocation.
 906	 *
 907	 * If a shared tree block is no longer referenced by its owner
 908	 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 909	 * use full backrefs for extent pointers in tree block.
 910	 *
 911	 * If a tree block is been relocating
 912	 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
 913	 * use full backrefs for extent pointers in tree block.
 914	 * The reason for this is some operations (such as drop tree)
 915	 * are only allowed for blocks use full backrefs.
 916	 */
 917
 918	if (btrfs_block_can_be_shared(root, buf)) {
 919		ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
 920					       btrfs_header_level(buf), 1,
 921					       &refs, &flags);
 922		if (ret)
 923			return ret;
 924		if (refs == 0) {
 925			ret = -EROFS;
 926			btrfs_handle_fs_error(fs_info, ret, NULL);
 927			return ret;
 928		}
 929	} else {
 930		refs = 1;
 931		if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 932		    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 933			flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
 934		else
 935			flags = 0;
 936	}
 937
 938	owner = btrfs_header_owner(buf);
 939	BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
 940	       !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
 941
 942	if (refs > 1) {
 943		if ((owner == root->root_key.objectid ||
 944		     root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 945		    !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 946			ret = btrfs_inc_ref(trans, root, buf, 1);
 947			if (ret)
 948				return ret;
 949
 950			if (root->root_key.objectid ==
 951			    BTRFS_TREE_RELOC_OBJECTID) {
 952				ret = btrfs_dec_ref(trans, root, buf, 0);
 953				if (ret)
 954					return ret;
 955				ret = btrfs_inc_ref(trans, root, cow, 1);
 956				if (ret)
 957					return ret;
 958			}
 959			new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 960		} else {
 961
 962			if (root->root_key.objectid ==
 963			    BTRFS_TREE_RELOC_OBJECTID)
 964				ret = btrfs_inc_ref(trans, root, cow, 1);
 965			else
 966				ret = btrfs_inc_ref(trans, root, cow, 0);
 967			if (ret)
 968				return ret;
 969		}
 970		if (new_flags != 0) {
 971			int level = btrfs_header_level(buf);
 972
 973			ret = btrfs_set_disk_extent_flags(trans,
 974							  buf->start,
 975							  buf->len,
 976							  new_flags, level, 0);
 977			if (ret)
 978				return ret;
 979		}
 980	} else {
 981		if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
 982			if (root->root_key.objectid ==
 983			    BTRFS_TREE_RELOC_OBJECTID)
 984				ret = btrfs_inc_ref(trans, root, cow, 1);
 985			else
 986				ret = btrfs_inc_ref(trans, root, cow, 0);
 987			if (ret)
 988				return ret;
 989			ret = btrfs_dec_ref(trans, root, buf, 1);
 990			if (ret)
 991				return ret;
 992		}
 993		btrfs_clean_tree_block(buf);
 994		*last_ref = 1;
 995	}
 996	return 0;
 997}
 998
 999static struct extent_buffer *alloc_tree_block_no_bg_flush(
1000					  struct btrfs_trans_handle *trans,
1001					  struct btrfs_root *root,
1002					  u64 parent_start,
1003					  const struct btrfs_disk_key *disk_key,
1004					  int level,
1005					  u64 hint,
1006					  u64 empty_size)
1007{
1008	struct btrfs_fs_info *fs_info = root->fs_info;
1009	struct extent_buffer *ret;
1010
1011	/*
1012	 * If we are COWing a node/leaf from the extent, chunk, device or free
1013	 * space trees, make sure that we do not finish block group creation of
1014	 * pending block groups. We do this to avoid a deadlock.
1015	 * COWing can result in allocation of a new chunk, and flushing pending
1016	 * block groups (btrfs_create_pending_block_groups()) can be triggered
1017	 * when finishing allocation of a new chunk. Creation of a pending block
1018	 * group modifies the extent, chunk, device and free space trees,
1019	 * therefore we could deadlock with ourselves since we are holding a
1020	 * lock on an extent buffer that btrfs_create_pending_block_groups() may
1021	 * try to COW later.
1022	 * For similar reasons, we also need to delay flushing pending block
1023	 * groups when splitting a leaf or node, from one of those trees, since
1024	 * we are holding a write lock on it and its parent or when inserting a
1025	 * new root node for one of those trees.
1026	 */
1027	if (root == fs_info->extent_root ||
1028	    root == fs_info->chunk_root ||
1029	    root == fs_info->dev_root ||
1030	    root == fs_info->free_space_root)
1031		trans->can_flush_pending_bgs = false;
1032
1033	ret = btrfs_alloc_tree_block(trans, root, parent_start,
1034				     root->root_key.objectid, disk_key, level,
1035				     hint, empty_size);
1036	trans->can_flush_pending_bgs = true;
1037
1038	return ret;
1039}
1040
1041/*
1042 * does the dirty work in cow of a single block.  The parent block (if
1043 * supplied) is updated to point to the new cow copy.  The new buffer is marked
1044 * dirty and returned locked.  If you modify the block it needs to be marked
1045 * dirty again.
1046 *
1047 * search_start -- an allocation hint for the new block
1048 *
1049 * empty_size -- a hint that you plan on doing more cow.  This is the size in
1050 * bytes the allocator should try to find free next to the block it returns.
1051 * This is just a hint and may be ignored by the allocator.
1052 */
1053static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
1054			     struct btrfs_root *root,
1055			     struct extent_buffer *buf,
1056			     struct extent_buffer *parent, int parent_slot,
1057			     struct extent_buffer **cow_ret,
1058			     u64 search_start, u64 empty_size)
1059{
1060	struct btrfs_fs_info *fs_info = root->fs_info;
1061	struct btrfs_disk_key disk_key;
1062	struct extent_buffer *cow;
1063	int level, ret;
1064	int last_ref = 0;
1065	int unlock_orig = 0;
1066	u64 parent_start = 0;
1067
1068	if (*cow_ret == buf)
1069		unlock_orig = 1;
1070
1071	btrfs_assert_tree_locked(buf);
1072
1073	WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1074		trans->transid != fs_info->running_transaction->transid);
1075	WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1076		trans->transid != root->last_trans);
1077
1078	level = btrfs_header_level(buf);
1079
1080	if (level == 0)
1081		btrfs_item_key(buf, &disk_key, 0);
1082	else
1083		btrfs_node_key(buf, &disk_key, 0);
1084
1085	if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
1086		parent_start = parent->start;
 
 
 
 
 
1087
1088	cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
1089					   level, search_start, empty_size);
 
1090	if (IS_ERR(cow))
1091		return PTR_ERR(cow);
1092
1093	/* cow is set to blocking by btrfs_init_new_buffer */
1094
1095	copy_extent_buffer_full(cow, buf);
1096	btrfs_set_header_bytenr(cow, cow->start);
1097	btrfs_set_header_generation(cow, trans->transid);
1098	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1099	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1100				     BTRFS_HEADER_FLAG_RELOC);
1101	if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1102		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1103	else
1104		btrfs_set_header_owner(cow, root->root_key.objectid);
1105
1106	write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
 
1107
1108	ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1109	if (ret) {
1110		btrfs_abort_transaction(trans, ret);
1111		return ret;
1112	}
1113
1114	if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
1115		ret = btrfs_reloc_cow_block(trans, root, buf, cow);
1116		if (ret) {
1117			btrfs_abort_transaction(trans, ret);
1118			return ret;
1119		}
1120	}
1121
1122	if (buf == root->node) {
1123		WARN_ON(parent && parent != buf);
1124		if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1125		    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1126			parent_start = buf->start;
 
 
1127
1128		extent_buffer_get(cow);
1129		ret = tree_mod_log_insert_root(root->node, cow, 1);
1130		BUG_ON(ret < 0);
1131		rcu_assign_pointer(root->node, cow);
1132
1133		btrfs_free_tree_block(trans, root, buf, parent_start,
1134				      last_ref);
1135		free_extent_buffer(buf);
1136		add_root_to_dirty_list(root);
1137	} else {
 
 
 
 
 
1138		WARN_ON(trans->transid != btrfs_header_generation(parent));
1139		tree_mod_log_insert_key(parent, parent_slot,
1140					MOD_LOG_KEY_REPLACE, GFP_NOFS);
1141		btrfs_set_node_blockptr(parent, parent_slot,
1142					cow->start);
1143		btrfs_set_node_ptr_generation(parent, parent_slot,
1144					      trans->transid);
1145		btrfs_mark_buffer_dirty(parent);
1146		if (last_ref) {
1147			ret = tree_mod_log_free_eb(buf);
1148			if (ret) {
1149				btrfs_abort_transaction(trans, ret);
1150				return ret;
1151			}
1152		}
1153		btrfs_free_tree_block(trans, root, buf, parent_start,
1154				      last_ref);
1155	}
1156	if (unlock_orig)
1157		btrfs_tree_unlock(buf);
1158	free_extent_buffer_stale(buf);
1159	btrfs_mark_buffer_dirty(cow);
1160	*cow_ret = cow;
1161	return 0;
1162}
1163
1164/*
1165 * returns the logical address of the oldest predecessor of the given root.
1166 * entries older than time_seq are ignored.
1167 */
1168static struct tree_mod_elem *__tree_mod_log_oldest_root(
1169		struct extent_buffer *eb_root, u64 time_seq)
 
1170{
1171	struct tree_mod_elem *tm;
1172	struct tree_mod_elem *found = NULL;
1173	u64 root_logical = eb_root->start;
1174	int looped = 0;
1175
1176	if (!time_seq)
1177		return NULL;
1178
1179	/*
1180	 * the very last operation that's logged for a root is the
1181	 * replacement operation (if it is replaced at all). this has
1182	 * the logical address of the *new* root, making it the very
1183	 * first operation that's logged for this root.
1184	 */
1185	while (1) {
1186		tm = tree_mod_log_search_oldest(eb_root->fs_info, root_logical,
1187						time_seq);
1188		if (!looped && !tm)
1189			return NULL;
1190		/*
1191		 * if there are no tree operation for the oldest root, we simply
1192		 * return it. this should only happen if that (old) root is at
1193		 * level 0.
1194		 */
1195		if (!tm)
1196			break;
1197
1198		/*
1199		 * if there's an operation that's not a root replacement, we
1200		 * found the oldest version of our root. normally, we'll find a
1201		 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1202		 */
1203		if (tm->op != MOD_LOG_ROOT_REPLACE)
1204			break;
1205
1206		found = tm;
1207		root_logical = tm->old_root.logical;
1208		looped = 1;
1209	}
1210
1211	/* if there's no old root to return, return what we found instead */
1212	if (!found)
1213		found = tm;
1214
1215	return found;
1216}
1217
1218/*
1219 * tm is a pointer to the first operation to rewind within eb. then, all
1220 * previous operations will be rewound (until we reach something older than
1221 * time_seq).
1222 */
1223static void
1224__tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1225		      u64 time_seq, struct tree_mod_elem *first_tm)
1226{
1227	u32 n;
1228	struct rb_node *next;
1229	struct tree_mod_elem *tm = first_tm;
1230	unsigned long o_dst;
1231	unsigned long o_src;
1232	unsigned long p_size = sizeof(struct btrfs_key_ptr);
1233
1234	n = btrfs_header_nritems(eb);
1235	read_lock(&fs_info->tree_mod_log_lock);
1236	while (tm && tm->seq >= time_seq) {
1237		/*
1238		 * all the operations are recorded with the operator used for
1239		 * the modification. as we're going backwards, we do the
1240		 * opposite of each operation here.
1241		 */
1242		switch (tm->op) {
1243		case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1244			BUG_ON(tm->slot < n);
1245			/* Fallthrough */
1246		case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1247		case MOD_LOG_KEY_REMOVE:
1248			btrfs_set_node_key(eb, &tm->key, tm->slot);
1249			btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1250			btrfs_set_node_ptr_generation(eb, tm->slot,
1251						      tm->generation);
1252			n++;
1253			break;
1254		case MOD_LOG_KEY_REPLACE:
1255			BUG_ON(tm->slot >= n);
1256			btrfs_set_node_key(eb, &tm->key, tm->slot);
1257			btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1258			btrfs_set_node_ptr_generation(eb, tm->slot,
1259						      tm->generation);
1260			break;
1261		case MOD_LOG_KEY_ADD:
1262			/* if a move operation is needed it's in the log */
1263			n--;
1264			break;
1265		case MOD_LOG_MOVE_KEYS:
1266			o_dst = btrfs_node_key_ptr_offset(tm->slot);
1267			o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1268			memmove_extent_buffer(eb, o_dst, o_src,
1269					      tm->move.nr_items * p_size);
1270			break;
1271		case MOD_LOG_ROOT_REPLACE:
1272			/*
1273			 * this operation is special. for roots, this must be
1274			 * handled explicitly before rewinding.
1275			 * for non-roots, this operation may exist if the node
1276			 * was a root: root A -> child B; then A gets empty and
1277			 * B is promoted to the new root. in the mod log, we'll
1278			 * have a root-replace operation for B, a tree block
1279			 * that is no root. we simply ignore that operation.
1280			 */
1281			break;
1282		}
1283		next = rb_next(&tm->node);
1284		if (!next)
1285			break;
1286		tm = rb_entry(next, struct tree_mod_elem, node);
1287		if (tm->logical != first_tm->logical)
1288			break;
1289	}
1290	read_unlock(&fs_info->tree_mod_log_lock);
1291	btrfs_set_header_nritems(eb, n);
1292}
1293
1294/*
1295 * Called with eb read locked. If the buffer cannot be rewound, the same buffer
1296 * is returned. If rewind operations happen, a fresh buffer is returned. The
1297 * returned buffer is always read-locked. If the returned buffer is not the
1298 * input buffer, the lock on the input buffer is released and the input buffer
1299 * is freed (its refcount is decremented).
1300 */
1301static struct extent_buffer *
1302tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
1303		    struct extent_buffer *eb, u64 time_seq)
1304{
1305	struct extent_buffer *eb_rewin;
1306	struct tree_mod_elem *tm;
1307
1308	if (!time_seq)
1309		return eb;
1310
1311	if (btrfs_header_level(eb) == 0)
1312		return eb;
1313
1314	tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1315	if (!tm)
1316		return eb;
1317
1318	btrfs_set_path_blocking(path);
1319	btrfs_set_lock_blocking_read(eb);
1320
1321	if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1322		BUG_ON(tm->slot != 0);
1323		eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
1324		if (!eb_rewin) {
1325			btrfs_tree_read_unlock_blocking(eb);
1326			free_extent_buffer(eb);
1327			return NULL;
1328		}
1329		btrfs_set_header_bytenr(eb_rewin, eb->start);
1330		btrfs_set_header_backref_rev(eb_rewin,
1331					     btrfs_header_backref_rev(eb));
1332		btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1333		btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1334	} else {
1335		eb_rewin = btrfs_clone_extent_buffer(eb);
1336		if (!eb_rewin) {
1337			btrfs_tree_read_unlock_blocking(eb);
1338			free_extent_buffer(eb);
1339			return NULL;
1340		}
1341	}
1342
 
1343	btrfs_tree_read_unlock_blocking(eb);
1344	free_extent_buffer(eb);
1345
 
1346	btrfs_tree_read_lock(eb_rewin);
1347	__tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
1348	WARN_ON(btrfs_header_nritems(eb_rewin) >
1349		BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1350
1351	return eb_rewin;
1352}
1353
1354/*
1355 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1356 * value. If there are no changes, the current root->root_node is returned. If
1357 * anything changed in between, there's a fresh buffer allocated on which the
1358 * rewind operations are done. In any case, the returned buffer is read locked.
1359 * Returns NULL on error (with no locks held).
1360 */
1361static inline struct extent_buffer *
1362get_old_root(struct btrfs_root *root, u64 time_seq)
1363{
1364	struct btrfs_fs_info *fs_info = root->fs_info;
1365	struct tree_mod_elem *tm;
1366	struct extent_buffer *eb = NULL;
1367	struct extent_buffer *eb_root;
1368	u64 eb_root_owner = 0;
1369	struct extent_buffer *old;
1370	struct tree_mod_root *old_root = NULL;
1371	u64 old_generation = 0;
1372	u64 logical;
1373	int level;
1374
1375	eb_root = btrfs_read_lock_root_node(root);
1376	tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1377	if (!tm)
1378		return eb_root;
1379
1380	if (tm->op == MOD_LOG_ROOT_REPLACE) {
1381		old_root = &tm->old_root;
1382		old_generation = tm->generation;
1383		logical = old_root->logical;
1384		level = old_root->level;
1385	} else {
1386		logical = eb_root->start;
1387		level = btrfs_header_level(eb_root);
1388	}
1389
1390	tm = tree_mod_log_search(fs_info, logical, time_seq);
1391	if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1392		btrfs_tree_read_unlock(eb_root);
1393		free_extent_buffer(eb_root);
1394		old = read_tree_block(fs_info, logical, 0, level, NULL);
1395		if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) {
1396			if (!IS_ERR(old))
1397				free_extent_buffer(old);
1398			btrfs_warn(fs_info,
1399				   "failed to read tree block %llu from get_old_root",
1400				   logical);
1401		} else {
1402			eb = btrfs_clone_extent_buffer(old);
1403			free_extent_buffer(old);
1404		}
1405	} else if (old_root) {
1406		eb_root_owner = btrfs_header_owner(eb_root);
1407		btrfs_tree_read_unlock(eb_root);
1408		free_extent_buffer(eb_root);
1409		eb = alloc_dummy_extent_buffer(fs_info, logical);
1410	} else {
1411		btrfs_set_lock_blocking_read(eb_root);
1412		eb = btrfs_clone_extent_buffer(eb_root);
1413		btrfs_tree_read_unlock_blocking(eb_root);
1414		free_extent_buffer(eb_root);
1415	}
1416
1417	if (!eb)
1418		return NULL;
 
1419	btrfs_tree_read_lock(eb);
1420	if (old_root) {
1421		btrfs_set_header_bytenr(eb, eb->start);
1422		btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1423		btrfs_set_header_owner(eb, eb_root_owner);
1424		btrfs_set_header_level(eb, old_root->level);
1425		btrfs_set_header_generation(eb, old_generation);
1426	}
1427	if (tm)
1428		__tree_mod_log_rewind(fs_info, eb, time_seq, tm);
1429	else
1430		WARN_ON(btrfs_header_level(eb) != 0);
1431	WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1432
1433	return eb;
1434}
1435
1436int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1437{
1438	struct tree_mod_elem *tm;
1439	int level;
1440	struct extent_buffer *eb_root = btrfs_root_node(root);
1441
1442	tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1443	if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1444		level = tm->old_root.level;
1445	} else {
1446		level = btrfs_header_level(eb_root);
1447	}
1448	free_extent_buffer(eb_root);
1449
1450	return level;
1451}
1452
1453static inline int should_cow_block(struct btrfs_trans_handle *trans,
1454				   struct btrfs_root *root,
1455				   struct extent_buffer *buf)
1456{
1457	if (btrfs_is_testing(root->fs_info))
1458		return 0;
1459
1460	/* Ensure we can see the FORCE_COW bit */
1461	smp_mb__before_atomic();
1462
1463	/*
1464	 * We do not need to cow a block if
1465	 * 1) this block is not created or changed in this transaction;
1466	 * 2) this block does not belong to TREE_RELOC tree;
1467	 * 3) the root is not forced COW.
1468	 *
1469	 * What is forced COW:
1470	 *    when we create snapshot during committing the transaction,
1471	 *    after we've finished copying src root, we must COW the shared
1472	 *    block to ensure the metadata consistency.
1473	 */
1474	if (btrfs_header_generation(buf) == trans->transid &&
1475	    !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1476	    !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1477	      btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1478	    !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
1479		return 0;
1480	return 1;
1481}
1482
1483/*
1484 * cows a single block, see __btrfs_cow_block for the real work.
1485 * This version of it has extra checks so that a block isn't COWed more than
1486 * once per transaction, as long as it hasn't been written yet
1487 */
1488noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1489		    struct btrfs_root *root, struct extent_buffer *buf,
1490		    struct extent_buffer *parent, int parent_slot,
1491		    struct extent_buffer **cow_ret)
1492{
1493	struct btrfs_fs_info *fs_info = root->fs_info;
1494	u64 search_start;
1495	int ret;
1496
1497	if (test_bit(BTRFS_ROOT_DELETING, &root->state))
1498		btrfs_err(fs_info,
1499			"COW'ing blocks on a fs root that's being dropped");
1500
1501	if (trans->transaction != fs_info->running_transaction)
1502		WARN(1, KERN_CRIT "trans %llu running %llu\n",
1503		       trans->transid,
1504		       fs_info->running_transaction->transid);
1505
1506	if (trans->transid != fs_info->generation)
1507		WARN(1, KERN_CRIT "trans %llu running %llu\n",
1508		       trans->transid, fs_info->generation);
1509
1510	if (!should_cow_block(trans, root, buf)) {
1511		trans->dirty = true;
1512		*cow_ret = buf;
1513		return 0;
1514	}
1515
1516	search_start = buf->start & ~((u64)SZ_1G - 1);
1517
1518	if (parent)
1519		btrfs_set_lock_blocking_write(parent);
1520	btrfs_set_lock_blocking_write(buf);
1521
1522	/*
1523	 * Before CoWing this block for later modification, check if it's
1524	 * the subtree root and do the delayed subtree trace if needed.
1525	 *
1526	 * Also We don't care about the error, as it's handled internally.
1527	 */
1528	btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
1529	ret = __btrfs_cow_block(trans, root, buf, parent,
1530				 parent_slot, cow_ret, search_start, 0);
1531
1532	trace_btrfs_cow_block(root, buf, *cow_ret);
1533
1534	return ret;
1535}
1536
1537/*
1538 * helper function for defrag to decide if two blocks pointed to by a
1539 * node are actually close by
1540 */
1541static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1542{
1543	if (blocknr < other && other - (blocknr + blocksize) < 32768)
1544		return 1;
1545	if (blocknr > other && blocknr - (other + blocksize) < 32768)
1546		return 1;
1547	return 0;
1548}
1549
1550/*
1551 * compare two keys in a memcmp fashion
1552 */
1553static int comp_keys(const struct btrfs_disk_key *disk,
1554		     const struct btrfs_key *k2)
1555{
1556	struct btrfs_key k1;
1557
1558	btrfs_disk_key_to_cpu(&k1, disk);
1559
1560	return btrfs_comp_cpu_keys(&k1, k2);
1561}
1562
1563/*
1564 * same as comp_keys only with two btrfs_key's
1565 */
1566int btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
1567{
1568	if (k1->objectid > k2->objectid)
1569		return 1;
1570	if (k1->objectid < k2->objectid)
1571		return -1;
1572	if (k1->type > k2->type)
1573		return 1;
1574	if (k1->type < k2->type)
1575		return -1;
1576	if (k1->offset > k2->offset)
1577		return 1;
1578	if (k1->offset < k2->offset)
1579		return -1;
1580	return 0;
1581}
1582
1583/*
1584 * this is used by the defrag code to go through all the
1585 * leaves pointed to by a node and reallocate them so that
1586 * disk order is close to key order
1587 */
1588int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1589		       struct btrfs_root *root, struct extent_buffer *parent,
1590		       int start_slot, u64 *last_ret,
1591		       struct btrfs_key *progress)
1592{
1593	struct btrfs_fs_info *fs_info = root->fs_info;
1594	struct extent_buffer *cur;
1595	u64 blocknr;
1596	u64 gen;
1597	u64 search_start = *last_ret;
1598	u64 last_block = 0;
1599	u64 other;
1600	u32 parent_nritems;
1601	int end_slot;
1602	int i;
1603	int err = 0;
1604	int parent_level;
1605	int uptodate;
1606	u32 blocksize;
1607	int progress_passed = 0;
1608	struct btrfs_disk_key disk_key;
1609
1610	parent_level = btrfs_header_level(parent);
1611
1612	WARN_ON(trans->transaction != fs_info->running_transaction);
1613	WARN_ON(trans->transid != fs_info->generation);
1614
1615	parent_nritems = btrfs_header_nritems(parent);
1616	blocksize = fs_info->nodesize;
1617	end_slot = parent_nritems - 1;
1618
1619	if (parent_nritems <= 1)
1620		return 0;
1621
1622	btrfs_set_lock_blocking_write(parent);
1623
1624	for (i = start_slot; i <= end_slot; i++) {
1625		struct btrfs_key first_key;
1626		int close = 1;
1627
1628		btrfs_node_key(parent, &disk_key, i);
1629		if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1630			continue;
1631
1632		progress_passed = 1;
1633		blocknr = btrfs_node_blockptr(parent, i);
1634		gen = btrfs_node_ptr_generation(parent, i);
1635		btrfs_node_key_to_cpu(parent, &first_key, i);
1636		if (last_block == 0)
1637			last_block = blocknr;
1638
1639		if (i > 0) {
1640			other = btrfs_node_blockptr(parent, i - 1);
1641			close = close_blocks(blocknr, other, blocksize);
1642		}
1643		if (!close && i < end_slot) {
1644			other = btrfs_node_blockptr(parent, i + 1);
1645			close = close_blocks(blocknr, other, blocksize);
1646		}
1647		if (close) {
1648			last_block = blocknr;
1649			continue;
1650		}
1651
1652		cur = find_extent_buffer(fs_info, blocknr);
1653		if (cur)
1654			uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1655		else
1656			uptodate = 0;
1657		if (!cur || !uptodate) {
1658			if (!cur) {
1659				cur = read_tree_block(fs_info, blocknr, gen,
1660						      parent_level - 1,
1661						      &first_key);
1662				if (IS_ERR(cur)) {
1663					return PTR_ERR(cur);
1664				} else if (!extent_buffer_uptodate(cur)) {
1665					free_extent_buffer(cur);
1666					return -EIO;
1667				}
1668			} else if (!uptodate) {
1669				err = btrfs_read_buffer(cur, gen,
1670						parent_level - 1,&first_key);
1671				if (err) {
1672					free_extent_buffer(cur);
1673					return err;
1674				}
1675			}
1676		}
1677		if (search_start == 0)
1678			search_start = last_block;
1679
1680		btrfs_tree_lock(cur);
1681		btrfs_set_lock_blocking_write(cur);
1682		err = __btrfs_cow_block(trans, root, cur, parent, i,
1683					&cur, search_start,
1684					min(16 * blocksize,
1685					    (end_slot - i) * blocksize));
1686		if (err) {
1687			btrfs_tree_unlock(cur);
1688			free_extent_buffer(cur);
1689			break;
1690		}
1691		search_start = cur->start;
1692		last_block = cur->start;
1693		*last_ret = search_start;
1694		btrfs_tree_unlock(cur);
1695		free_extent_buffer(cur);
1696	}
1697	return err;
1698}
1699
1700/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1701 * search for key in the extent_buffer.  The items start at offset p,
1702 * and they are item_size apart.  There are 'max' items in p.
1703 *
1704 * the slot in the array is returned via slot, and it points to
1705 * the place where you would insert key if it is not found in
1706 * the array.
1707 *
1708 * slot may point to max if the key is bigger than all of the keys
1709 */
1710static noinline int generic_bin_search(struct extent_buffer *eb,
1711				       unsigned long p, int item_size,
1712				       const struct btrfs_key *key,
1713				       int max, int *slot)
1714{
1715	int low = 0;
1716	int high = max;
1717	int mid;
1718	int ret;
1719	struct btrfs_disk_key *tmp = NULL;
1720	struct btrfs_disk_key unaligned;
1721	unsigned long offset;
1722	char *kaddr = NULL;
1723	unsigned long map_start = 0;
1724	unsigned long map_len = 0;
1725	int err;
1726
1727	if (low > high) {
1728		btrfs_err(eb->fs_info,
1729		 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
1730			  __func__, low, high, eb->start,
1731			  btrfs_header_owner(eb), btrfs_header_level(eb));
1732		return -EINVAL;
1733	}
1734
1735	while (low < high) {
1736		mid = (low + high) / 2;
1737		offset = p + mid * item_size;
1738
1739		if (!kaddr || offset < map_start ||
1740		    (offset + sizeof(struct btrfs_disk_key)) >
1741		    map_start + map_len) {
1742
1743			err = map_private_extent_buffer(eb, offset,
1744						sizeof(struct btrfs_disk_key),
1745						&kaddr, &map_start, &map_len);
1746
1747			if (!err) {
1748				tmp = (struct btrfs_disk_key *)(kaddr + offset -
1749							map_start);
1750			} else if (err == 1) {
1751				read_extent_buffer(eb, &unaligned,
1752						   offset, sizeof(unaligned));
1753				tmp = &unaligned;
1754			} else {
1755				return err;
1756			}
1757
1758		} else {
1759			tmp = (struct btrfs_disk_key *)(kaddr + offset -
1760							map_start);
1761		}
1762		ret = comp_keys(tmp, key);
1763
1764		if (ret < 0)
1765			low = mid + 1;
1766		else if (ret > 0)
1767			high = mid;
1768		else {
1769			*slot = mid;
1770			return 0;
1771		}
1772	}
1773	*slot = low;
1774	return 1;
1775}
1776
1777/*
1778 * simple bin_search frontend that does the right thing for
1779 * leaves vs nodes
1780 */
1781int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
1782		     int level, int *slot)
1783{
1784	if (level == 0)
1785		return generic_bin_search(eb,
1786					  offsetof(struct btrfs_leaf, items),
1787					  sizeof(struct btrfs_item),
1788					  key, btrfs_header_nritems(eb),
1789					  slot);
1790	else
1791		return generic_bin_search(eb,
1792					  offsetof(struct btrfs_node, ptrs),
1793					  sizeof(struct btrfs_key_ptr),
1794					  key, btrfs_header_nritems(eb),
1795					  slot);
1796}
1797
 
 
 
 
 
 
1798static void root_add_used(struct btrfs_root *root, u32 size)
1799{
1800	spin_lock(&root->accounting_lock);
1801	btrfs_set_root_used(&root->root_item,
1802			    btrfs_root_used(&root->root_item) + size);
1803	spin_unlock(&root->accounting_lock);
1804}
1805
1806static void root_sub_used(struct btrfs_root *root, u32 size)
1807{
1808	spin_lock(&root->accounting_lock);
1809	btrfs_set_root_used(&root->root_item,
1810			    btrfs_root_used(&root->root_item) - size);
1811	spin_unlock(&root->accounting_lock);
1812}
1813
1814/* given a node and slot number, this reads the blocks it points to.  The
1815 * extent buffer is returned with a reference taken (but unlocked).
 
1816 */
1817struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
1818					   int slot)
1819{
1820	int level = btrfs_header_level(parent);
1821	struct extent_buffer *eb;
1822	struct btrfs_key first_key;
1823
1824	if (slot < 0 || slot >= btrfs_header_nritems(parent))
1825		return ERR_PTR(-ENOENT);
 
 
1826
1827	BUG_ON(level == 0);
1828
1829	btrfs_node_key_to_cpu(parent, &first_key, slot);
1830	eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
1831			     btrfs_node_ptr_generation(parent, slot),
1832			     level - 1, &first_key);
1833	if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
1834		free_extent_buffer(eb);
1835		eb = ERR_PTR(-EIO);
1836	}
1837
1838	return eb;
1839}
1840
1841/*
1842 * node level balancing, used to make sure nodes are in proper order for
1843 * item deletion.  We balance from the top down, so we have to make sure
1844 * that a deletion won't leave an node completely empty later on.
1845 */
1846static noinline int balance_level(struct btrfs_trans_handle *trans,
1847			 struct btrfs_root *root,
1848			 struct btrfs_path *path, int level)
1849{
1850	struct btrfs_fs_info *fs_info = root->fs_info;
1851	struct extent_buffer *right = NULL;
1852	struct extent_buffer *mid;
1853	struct extent_buffer *left = NULL;
1854	struct extent_buffer *parent = NULL;
1855	int ret = 0;
1856	int wret;
1857	int pslot;
1858	int orig_slot = path->slots[level];
1859	u64 orig_ptr;
1860
1861	ASSERT(level > 0);
 
1862
1863	mid = path->nodes[level];
1864
1865	WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1866		path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1867	WARN_ON(btrfs_header_generation(mid) != trans->transid);
1868
1869	orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1870
1871	if (level < BTRFS_MAX_LEVEL - 1) {
1872		parent = path->nodes[level + 1];
1873		pslot = path->slots[level + 1];
1874	}
1875
1876	/*
1877	 * deal with the case where there is only one pointer in the root
1878	 * by promoting the node below to a root
1879	 */
1880	if (!parent) {
1881		struct extent_buffer *child;
1882
1883		if (btrfs_header_nritems(mid) != 1)
1884			return 0;
1885
1886		/* promote the child to a root */
1887		child = btrfs_read_node_slot(mid, 0);
1888		if (IS_ERR(child)) {
1889			ret = PTR_ERR(child);
1890			btrfs_handle_fs_error(fs_info, ret, NULL);
1891			goto enospc;
1892		}
1893
1894		btrfs_tree_lock(child);
1895		btrfs_set_lock_blocking_write(child);
1896		ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1897		if (ret) {
1898			btrfs_tree_unlock(child);
1899			free_extent_buffer(child);
1900			goto enospc;
1901		}
1902
1903		ret = tree_mod_log_insert_root(root->node, child, 1);
1904		BUG_ON(ret < 0);
1905		rcu_assign_pointer(root->node, child);
1906
1907		add_root_to_dirty_list(root);
1908		btrfs_tree_unlock(child);
1909
1910		path->locks[level] = 0;
1911		path->nodes[level] = NULL;
1912		btrfs_clean_tree_block(mid);
1913		btrfs_tree_unlock(mid);
1914		/* once for the path */
1915		free_extent_buffer(mid);
1916
1917		root_sub_used(root, mid->len);
1918		btrfs_free_tree_block(trans, root, mid, 0, 1);
1919		/* once for the root ptr */
1920		free_extent_buffer_stale(mid);
1921		return 0;
1922	}
1923	if (btrfs_header_nritems(mid) >
1924	    BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1925		return 0;
1926
1927	left = btrfs_read_node_slot(parent, pslot - 1);
1928	if (IS_ERR(left))
1929		left = NULL;
1930
1931	if (left) {
1932		btrfs_tree_lock(left);
1933		btrfs_set_lock_blocking_write(left);
1934		wret = btrfs_cow_block(trans, root, left,
1935				       parent, pslot - 1, &left);
1936		if (wret) {
1937			ret = wret;
1938			goto enospc;
1939		}
1940	}
1941
1942	right = btrfs_read_node_slot(parent, pslot + 1);
1943	if (IS_ERR(right))
1944		right = NULL;
1945
1946	if (right) {
1947		btrfs_tree_lock(right);
1948		btrfs_set_lock_blocking_write(right);
1949		wret = btrfs_cow_block(trans, root, right,
1950				       parent, pslot + 1, &right);
1951		if (wret) {
1952			ret = wret;
1953			goto enospc;
1954		}
1955	}
1956
1957	/* first, try to make some room in the middle buffer */
1958	if (left) {
1959		orig_slot += btrfs_header_nritems(left);
1960		wret = push_node_left(trans, left, mid, 1);
1961		if (wret < 0)
1962			ret = wret;
1963	}
1964
1965	/*
1966	 * then try to empty the right most buffer into the middle
1967	 */
1968	if (right) {
1969		wret = push_node_left(trans, mid, right, 1);
1970		if (wret < 0 && wret != -ENOSPC)
1971			ret = wret;
1972		if (btrfs_header_nritems(right) == 0) {
1973			btrfs_clean_tree_block(right);
1974			btrfs_tree_unlock(right);
1975			del_ptr(root, path, level + 1, pslot + 1);
1976			root_sub_used(root, right->len);
1977			btrfs_free_tree_block(trans, root, right, 0, 1);
1978			free_extent_buffer_stale(right);
1979			right = NULL;
1980		} else {
1981			struct btrfs_disk_key right_key;
1982			btrfs_node_key(right, &right_key, 0);
1983			ret = tree_mod_log_insert_key(parent, pslot + 1,
1984					MOD_LOG_KEY_REPLACE, GFP_NOFS);
1985			BUG_ON(ret < 0);
1986			btrfs_set_node_key(parent, &right_key, pslot + 1);
1987			btrfs_mark_buffer_dirty(parent);
1988		}
1989	}
1990	if (btrfs_header_nritems(mid) == 1) {
1991		/*
1992		 * we're not allowed to leave a node with one item in the
1993		 * tree during a delete.  A deletion from lower in the tree
1994		 * could try to delete the only pointer in this node.
1995		 * So, pull some keys from the left.
1996		 * There has to be a left pointer at this point because
1997		 * otherwise we would have pulled some pointers from the
1998		 * right
1999		 */
2000		if (!left) {
2001			ret = -EROFS;
2002			btrfs_handle_fs_error(fs_info, ret, NULL);
2003			goto enospc;
2004		}
2005		wret = balance_node_right(trans, mid, left);
2006		if (wret < 0) {
2007			ret = wret;
2008			goto enospc;
2009		}
2010		if (wret == 1) {
2011			wret = push_node_left(trans, left, mid, 1);
2012			if (wret < 0)
2013				ret = wret;
2014		}
2015		BUG_ON(wret == 1);
2016	}
2017	if (btrfs_header_nritems(mid) == 0) {
2018		btrfs_clean_tree_block(mid);
2019		btrfs_tree_unlock(mid);
2020		del_ptr(root, path, level + 1, pslot);
2021		root_sub_used(root, mid->len);
2022		btrfs_free_tree_block(trans, root, mid, 0, 1);
2023		free_extent_buffer_stale(mid);
2024		mid = NULL;
2025	} else {
2026		/* update the parent key to reflect our changes */
2027		struct btrfs_disk_key mid_key;
2028		btrfs_node_key(mid, &mid_key, 0);
2029		ret = tree_mod_log_insert_key(parent, pslot,
2030				MOD_LOG_KEY_REPLACE, GFP_NOFS);
2031		BUG_ON(ret < 0);
2032		btrfs_set_node_key(parent, &mid_key, pslot);
2033		btrfs_mark_buffer_dirty(parent);
2034	}
2035
2036	/* update the path */
2037	if (left) {
2038		if (btrfs_header_nritems(left) > orig_slot) {
2039			extent_buffer_get(left);
2040			/* left was locked after cow */
2041			path->nodes[level] = left;
2042			path->slots[level + 1] -= 1;
2043			path->slots[level] = orig_slot;
2044			if (mid) {
2045				btrfs_tree_unlock(mid);
2046				free_extent_buffer(mid);
2047			}
2048		} else {
2049			orig_slot -= btrfs_header_nritems(left);
2050			path->slots[level] = orig_slot;
2051		}
2052	}
2053	/* double check we haven't messed things up */
2054	if (orig_ptr !=
2055	    btrfs_node_blockptr(path->nodes[level], path->slots[level]))
2056		BUG();
2057enospc:
2058	if (right) {
2059		btrfs_tree_unlock(right);
2060		free_extent_buffer(right);
2061	}
2062	if (left) {
2063		if (path->nodes[level] != left)
2064			btrfs_tree_unlock(left);
2065		free_extent_buffer(left);
2066	}
2067	return ret;
2068}
2069
2070/* Node balancing for insertion.  Here we only split or push nodes around
2071 * when they are completely full.  This is also done top down, so we
2072 * have to be pessimistic.
2073 */
2074static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
2075					  struct btrfs_root *root,
2076					  struct btrfs_path *path, int level)
2077{
2078	struct btrfs_fs_info *fs_info = root->fs_info;
2079	struct extent_buffer *right = NULL;
2080	struct extent_buffer *mid;
2081	struct extent_buffer *left = NULL;
2082	struct extent_buffer *parent = NULL;
2083	int ret = 0;
2084	int wret;
2085	int pslot;
2086	int orig_slot = path->slots[level];
2087
2088	if (level == 0)
2089		return 1;
2090
2091	mid = path->nodes[level];
2092	WARN_ON(btrfs_header_generation(mid) != trans->transid);
2093
2094	if (level < BTRFS_MAX_LEVEL - 1) {
2095		parent = path->nodes[level + 1];
2096		pslot = path->slots[level + 1];
2097	}
2098
2099	if (!parent)
2100		return 1;
2101
2102	left = btrfs_read_node_slot(parent, pslot - 1);
2103	if (IS_ERR(left))
2104		left = NULL;
2105
2106	/* first, try to make some room in the middle buffer */
2107	if (left) {
2108		u32 left_nr;
2109
2110		btrfs_tree_lock(left);
2111		btrfs_set_lock_blocking_write(left);
2112
2113		left_nr = btrfs_header_nritems(left);
2114		if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2115			wret = 1;
2116		} else {
2117			ret = btrfs_cow_block(trans, root, left, parent,
2118					      pslot - 1, &left);
2119			if (ret)
2120				wret = 1;
2121			else {
2122				wret = push_node_left(trans, left, mid, 0);
 
2123			}
2124		}
2125		if (wret < 0)
2126			ret = wret;
2127		if (wret == 0) {
2128			struct btrfs_disk_key disk_key;
2129			orig_slot += left_nr;
2130			btrfs_node_key(mid, &disk_key, 0);
2131			ret = tree_mod_log_insert_key(parent, pslot,
2132					MOD_LOG_KEY_REPLACE, GFP_NOFS);
2133			BUG_ON(ret < 0);
2134			btrfs_set_node_key(parent, &disk_key, pslot);
2135			btrfs_mark_buffer_dirty(parent);
2136			if (btrfs_header_nritems(left) > orig_slot) {
2137				path->nodes[level] = left;
2138				path->slots[level + 1] -= 1;
2139				path->slots[level] = orig_slot;
2140				btrfs_tree_unlock(mid);
2141				free_extent_buffer(mid);
2142			} else {
2143				orig_slot -=
2144					btrfs_header_nritems(left);
2145				path->slots[level] = orig_slot;
2146				btrfs_tree_unlock(left);
2147				free_extent_buffer(left);
2148			}
2149			return 0;
2150		}
2151		btrfs_tree_unlock(left);
2152		free_extent_buffer(left);
2153	}
2154	right = btrfs_read_node_slot(parent, pslot + 1);
2155	if (IS_ERR(right))
2156		right = NULL;
2157
2158	/*
2159	 * then try to empty the right most buffer into the middle
2160	 */
2161	if (right) {
2162		u32 right_nr;
2163
2164		btrfs_tree_lock(right);
2165		btrfs_set_lock_blocking_write(right);
2166
2167		right_nr = btrfs_header_nritems(right);
2168		if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2169			wret = 1;
2170		} else {
2171			ret = btrfs_cow_block(trans, root, right,
2172					      parent, pslot + 1,
2173					      &right);
2174			if (ret)
2175				wret = 1;
2176			else {
2177				wret = balance_node_right(trans, right, mid);
 
2178			}
2179		}
2180		if (wret < 0)
2181			ret = wret;
2182		if (wret == 0) {
2183			struct btrfs_disk_key disk_key;
2184
2185			btrfs_node_key(right, &disk_key, 0);
2186			ret = tree_mod_log_insert_key(parent, pslot + 1,
2187					MOD_LOG_KEY_REPLACE, GFP_NOFS);
2188			BUG_ON(ret < 0);
2189			btrfs_set_node_key(parent, &disk_key, pslot + 1);
2190			btrfs_mark_buffer_dirty(parent);
2191
2192			if (btrfs_header_nritems(mid) <= orig_slot) {
2193				path->nodes[level] = right;
2194				path->slots[level + 1] += 1;
2195				path->slots[level] = orig_slot -
2196					btrfs_header_nritems(mid);
2197				btrfs_tree_unlock(mid);
2198				free_extent_buffer(mid);
2199			} else {
2200				btrfs_tree_unlock(right);
2201				free_extent_buffer(right);
2202			}
2203			return 0;
2204		}
2205		btrfs_tree_unlock(right);
2206		free_extent_buffer(right);
2207	}
2208	return 1;
2209}
2210
2211/*
2212 * readahead one full node of leaves, finding things that are close
2213 * to the block in 'slot', and triggering ra on them.
2214 */
2215static void reada_for_search(struct btrfs_fs_info *fs_info,
2216			     struct btrfs_path *path,
2217			     int level, int slot, u64 objectid)
2218{
2219	struct extent_buffer *node;
2220	struct btrfs_disk_key disk_key;
2221	u32 nritems;
2222	u64 search;
2223	u64 target;
2224	u64 nread = 0;
 
2225	struct extent_buffer *eb;
2226	u32 nr;
2227	u32 blocksize;
2228	u32 nscan = 0;
2229
2230	if (level != 1)
2231		return;
2232
2233	if (!path->nodes[level])
2234		return;
2235
2236	node = path->nodes[level];
2237
2238	search = btrfs_node_blockptr(node, slot);
2239	blocksize = fs_info->nodesize;
2240	eb = find_extent_buffer(fs_info, search);
2241	if (eb) {
2242		free_extent_buffer(eb);
2243		return;
2244	}
2245
2246	target = search;
2247
2248	nritems = btrfs_header_nritems(node);
2249	nr = slot;
2250
2251	while (1) {
2252		if (path->reada == READA_BACK) {
2253			if (nr == 0)
2254				break;
2255			nr--;
2256		} else if (path->reada == READA_FORWARD) {
2257			nr++;
2258			if (nr >= nritems)
2259				break;
2260		}
2261		if (path->reada == READA_BACK && objectid) {
2262			btrfs_node_key(node, &disk_key, nr);
2263			if (btrfs_disk_key_objectid(&disk_key) != objectid)
2264				break;
2265		}
2266		search = btrfs_node_blockptr(node, nr);
2267		if ((search <= target && target - search <= 65536) ||
2268		    (search > target && search - target <= 65536)) {
2269			readahead_tree_block(fs_info, search);
 
2270			nread += blocksize;
2271		}
2272		nscan++;
2273		if ((nread > 65536 || nscan > 32))
2274			break;
2275	}
2276}
2277
2278static noinline void reada_for_balance(struct btrfs_fs_info *fs_info,
2279				       struct btrfs_path *path, int level)
2280{
2281	int slot;
2282	int nritems;
2283	struct extent_buffer *parent;
2284	struct extent_buffer *eb;
2285	u64 gen;
2286	u64 block1 = 0;
2287	u64 block2 = 0;
2288
2289	parent = path->nodes[level + 1];
2290	if (!parent)
2291		return;
2292
2293	nritems = btrfs_header_nritems(parent);
2294	slot = path->slots[level + 1];
2295
2296	if (slot > 0) {
2297		block1 = btrfs_node_blockptr(parent, slot - 1);
2298		gen = btrfs_node_ptr_generation(parent, slot - 1);
2299		eb = find_extent_buffer(fs_info, block1);
2300		/*
2301		 * if we get -eagain from btrfs_buffer_uptodate, we
2302		 * don't want to return eagain here.  That will loop
2303		 * forever
2304		 */
2305		if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2306			block1 = 0;
2307		free_extent_buffer(eb);
2308	}
2309	if (slot + 1 < nritems) {
2310		block2 = btrfs_node_blockptr(parent, slot + 1);
2311		gen = btrfs_node_ptr_generation(parent, slot + 1);
2312		eb = find_extent_buffer(fs_info, block2);
2313		if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2314			block2 = 0;
2315		free_extent_buffer(eb);
2316	}
2317
2318	if (block1)
2319		readahead_tree_block(fs_info, block1);
2320	if (block2)
2321		readahead_tree_block(fs_info, block2);
2322}
2323
2324
2325/*
2326 * when we walk down the tree, it is usually safe to unlock the higher layers
2327 * in the tree.  The exceptions are when our path goes through slot 0, because
2328 * operations on the tree might require changing key pointers higher up in the
2329 * tree.
2330 *
2331 * callers might also have set path->keep_locks, which tells this code to keep
2332 * the lock if the path points to the last slot in the block.  This is part of
2333 * walking through the tree, and selecting the next slot in the higher block.
2334 *
2335 * lowest_unlock sets the lowest level in the tree we're allowed to unlock.  so
2336 * if lowest_unlock is 1, level 0 won't be unlocked
2337 */
2338static noinline void unlock_up(struct btrfs_path *path, int level,
2339			       int lowest_unlock, int min_write_lock_level,
2340			       int *write_lock_level)
2341{
2342	int i;
2343	int skip_level = level;
2344	int no_skips = 0;
2345	struct extent_buffer *t;
2346
2347	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2348		if (!path->nodes[i])
2349			break;
2350		if (!path->locks[i])
2351			break;
2352		if (!no_skips && path->slots[i] == 0) {
2353			skip_level = i + 1;
2354			continue;
2355		}
2356		if (!no_skips && path->keep_locks) {
2357			u32 nritems;
2358			t = path->nodes[i];
2359			nritems = btrfs_header_nritems(t);
2360			if (nritems < 1 || path->slots[i] >= nritems - 1) {
2361				skip_level = i + 1;
2362				continue;
2363			}
2364		}
2365		if (skip_level < i && i >= lowest_unlock)
2366			no_skips = 1;
2367
2368		t = path->nodes[i];
2369		if (i >= lowest_unlock && i > skip_level) {
2370			btrfs_tree_unlock_rw(t, path->locks[i]);
2371			path->locks[i] = 0;
2372			if (write_lock_level &&
2373			    i > min_write_lock_level &&
2374			    i <= *write_lock_level) {
2375				*write_lock_level = i - 1;
2376			}
2377		}
2378	}
2379}
2380
2381/*
2382 * This releases any locks held in the path starting at level and
2383 * going all the way up to the root.
2384 *
2385 * btrfs_search_slot will keep the lock held on higher nodes in a few
2386 * corner cases, such as COW of the block at slot zero in the node.  This
2387 * ignores those rules, and it should only be called when there are no
2388 * more updates to be done higher up in the tree.
2389 */
2390noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2391{
2392	int i;
2393
2394	if (path->keep_locks)
2395		return;
2396
2397	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2398		if (!path->nodes[i])
2399			continue;
2400		if (!path->locks[i])
2401			continue;
2402		btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2403		path->locks[i] = 0;
2404	}
2405}
2406
2407/*
2408 * helper function for btrfs_search_slot.  The goal is to find a block
2409 * in cache without setting the path to blocking.  If we find the block
2410 * we return zero and the path is unchanged.
2411 *
2412 * If we can't find the block, we set the path blocking and do some
2413 * reada.  -EAGAIN is returned and the search must be repeated.
2414 */
2415static int
2416read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
2417		      struct extent_buffer **eb_ret, int level, int slot,
2418		      const struct btrfs_key *key)
 
2419{
2420	struct btrfs_fs_info *fs_info = root->fs_info;
2421	u64 blocknr;
2422	u64 gen;
2423	struct extent_buffer *b = *eb_ret;
2424	struct extent_buffer *tmp;
2425	struct btrfs_key first_key;
2426	int ret;
2427	int parent_level;
2428
2429	blocknr = btrfs_node_blockptr(b, slot);
2430	gen = btrfs_node_ptr_generation(b, slot);
2431	parent_level = btrfs_header_level(b);
2432	btrfs_node_key_to_cpu(b, &first_key, slot);
2433
2434	tmp = find_extent_buffer(fs_info, blocknr);
2435	if (tmp) {
2436		/* first we do an atomic uptodate check */
2437		if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2438			/*
2439			 * Do extra check for first_key, eb can be stale due to
2440			 * being cached, read from scrub, or have multiple
2441			 * parents (shared tree blocks).
2442			 */
2443			if (btrfs_verify_level_key(tmp,
2444					parent_level - 1, &first_key, gen)) {
2445				free_extent_buffer(tmp);
2446				return -EUCLEAN;
2447			}
2448			*eb_ret = tmp;
2449			return 0;
2450		}
2451
2452		/* the pages were up to date, but we failed
2453		 * the generation number check.  Do a full
2454		 * read for the generation number that is correct.
2455		 * We must do this without dropping locks so
2456		 * we can trust our generation number
2457		 */
2458		btrfs_set_path_blocking(p);
2459
2460		/* now we're allowed to do a blocking uptodate check */
2461		ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
2462		if (!ret) {
2463			*eb_ret = tmp;
2464			return 0;
2465		}
2466		free_extent_buffer(tmp);
2467		btrfs_release_path(p);
2468		return -EIO;
2469	}
2470
2471	/*
2472	 * reduce lock contention at high levels
2473	 * of the btree by dropping locks before
2474	 * we read.  Don't release the lock on the current
2475	 * level because we need to walk this node to figure
2476	 * out which blocks to read.
2477	 */
2478	btrfs_unlock_up_safe(p, level + 1);
2479	btrfs_set_path_blocking(p);
2480
 
2481	if (p->reada != READA_NONE)
2482		reada_for_search(fs_info, p, level, slot, key->objectid);
 
 
2483
2484	ret = -EAGAIN;
2485	tmp = read_tree_block(fs_info, blocknr, gen, parent_level - 1,
2486			      &first_key);
2487	if (!IS_ERR(tmp)) {
2488		/*
2489		 * If the read above didn't mark this buffer up to date,
2490		 * it will never end up being up to date.  Set ret to EIO now
2491		 * and give up so that our caller doesn't loop forever
2492		 * on our EAGAINs.
2493		 */
2494		if (!extent_buffer_uptodate(tmp))
2495			ret = -EIO;
2496		free_extent_buffer(tmp);
2497	} else {
2498		ret = PTR_ERR(tmp);
2499	}
2500
2501	btrfs_release_path(p);
2502	return ret;
2503}
2504
2505/*
2506 * helper function for btrfs_search_slot.  This does all of the checks
2507 * for node-level blocks and does any balancing required based on
2508 * the ins_len.
2509 *
2510 * If no extra work was required, zero is returned.  If we had to
2511 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2512 * start over
2513 */
2514static int
2515setup_nodes_for_search(struct btrfs_trans_handle *trans,
2516		       struct btrfs_root *root, struct btrfs_path *p,
2517		       struct extent_buffer *b, int level, int ins_len,
2518		       int *write_lock_level)
2519{
2520	struct btrfs_fs_info *fs_info = root->fs_info;
2521	int ret;
2522
2523	if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2524	    BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
2525		int sret;
2526
2527		if (*write_lock_level < level + 1) {
2528			*write_lock_level = level + 1;
2529			btrfs_release_path(p);
2530			goto again;
2531		}
2532
2533		btrfs_set_path_blocking(p);
2534		reada_for_balance(fs_info, p, level);
2535		sret = split_node(trans, root, p, level);
 
2536
2537		BUG_ON(sret > 0);
2538		if (sret) {
2539			ret = sret;
2540			goto done;
2541		}
2542		b = p->nodes[level];
2543	} else if (ins_len < 0 && btrfs_header_nritems(b) <
2544		   BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
2545		int sret;
2546
2547		if (*write_lock_level < level + 1) {
2548			*write_lock_level = level + 1;
2549			btrfs_release_path(p);
2550			goto again;
2551		}
2552
2553		btrfs_set_path_blocking(p);
2554		reada_for_balance(fs_info, p, level);
2555		sret = balance_level(trans, root, p, level);
 
2556
2557		if (sret) {
2558			ret = sret;
2559			goto done;
2560		}
2561		b = p->nodes[level];
2562		if (!b) {
2563			btrfs_release_path(p);
2564			goto again;
2565		}
2566		BUG_ON(btrfs_header_nritems(b) == 1);
2567	}
2568	return 0;
2569
2570again:
2571	ret = -EAGAIN;
2572done:
2573	return ret;
2574}
2575
2576static int key_search(struct extent_buffer *b, const struct btrfs_key *key,
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2577		      int level, int *prev_cmp, int *slot)
2578{
2579	if (*prev_cmp != 0) {
2580		*prev_cmp = btrfs_bin_search(b, key, level, slot);
2581		return *prev_cmp;
2582	}
2583
 
2584	*slot = 0;
2585
2586	return 0;
2587}
2588
2589int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
2590		u64 iobjectid, u64 ioff, u8 key_type,
2591		struct btrfs_key *found_key)
2592{
2593	int ret;
2594	struct btrfs_key key;
2595	struct extent_buffer *eb;
2596
2597	ASSERT(path);
2598	ASSERT(found_key);
2599
2600	key.type = key_type;
2601	key.objectid = iobjectid;
2602	key.offset = ioff;
2603
2604	ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
2605	if (ret < 0)
2606		return ret;
2607
2608	eb = path->nodes[0];
2609	if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
2610		ret = btrfs_next_leaf(fs_root, path);
2611		if (ret)
2612			return ret;
2613		eb = path->nodes[0];
2614	}
2615
2616	btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
2617	if (found_key->type != key.type ||
2618			found_key->objectid != key.objectid)
2619		return 1;
2620
2621	return 0;
2622}
2623
2624static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
2625							struct btrfs_path *p,
2626							int write_lock_level)
2627{
2628	struct btrfs_fs_info *fs_info = root->fs_info;
2629	struct extent_buffer *b;
2630	int root_lock;
2631	int level = 0;
2632
2633	/* We try very hard to do read locks on the root */
2634	root_lock = BTRFS_READ_LOCK;
2635
2636	if (p->search_commit_root) {
2637		/*
2638		 * The commit roots are read only so we always do read locks,
2639		 * and we always must hold the commit_root_sem when doing
2640		 * searches on them, the only exception is send where we don't
2641		 * want to block transaction commits for a long time, so
2642		 * we need to clone the commit root in order to avoid races
2643		 * with transaction commits that create a snapshot of one of
2644		 * the roots used by a send operation.
2645		 */
2646		if (p->need_commit_sem) {
2647			down_read(&fs_info->commit_root_sem);
2648			b = btrfs_clone_extent_buffer(root->commit_root);
2649			up_read(&fs_info->commit_root_sem);
2650			if (!b)
2651				return ERR_PTR(-ENOMEM);
2652
2653		} else {
2654			b = root->commit_root;
2655			extent_buffer_get(b);
2656		}
2657		level = btrfs_header_level(b);
2658		/*
2659		 * Ensure that all callers have set skip_locking when
2660		 * p->search_commit_root = 1.
2661		 */
2662		ASSERT(p->skip_locking == 1);
2663
2664		goto out;
2665	}
2666
2667	if (p->skip_locking) {
2668		b = btrfs_root_node(root);
2669		level = btrfs_header_level(b);
2670		goto out;
2671	}
2672
2673	/*
2674	 * If the level is set to maximum, we can skip trying to get the read
2675	 * lock.
2676	 */
2677	if (write_lock_level < BTRFS_MAX_LEVEL) {
2678		/*
2679		 * We don't know the level of the root node until we actually
2680		 * have it read locked
2681		 */
2682		b = btrfs_read_lock_root_node(root);
2683		level = btrfs_header_level(b);
2684		if (level > write_lock_level)
2685			goto out;
2686
2687		/* Whoops, must trade for write lock */
2688		btrfs_tree_read_unlock(b);
2689		free_extent_buffer(b);
2690	}
2691
2692	b = btrfs_lock_root_node(root);
2693	root_lock = BTRFS_WRITE_LOCK;
2694
2695	/* The level might have changed, check again */
2696	level = btrfs_header_level(b);
2697
2698out:
2699	p->nodes[level] = b;
2700	if (!p->skip_locking)
2701		p->locks[level] = root_lock;
2702	/*
2703	 * Callers are responsible for dropping b's references.
2704	 */
2705	return b;
2706}
2707
2708
2709/*
2710 * btrfs_search_slot - look for a key in a tree and perform necessary
2711 * modifications to preserve tree invariants.
2712 *
2713 * @trans:	Handle of transaction, used when modifying the tree
2714 * @p:		Holds all btree nodes along the search path
2715 * @root:	The root node of the tree
2716 * @key:	The key we are looking for
2717 * @ins_len:	Indicates purpose of search, for inserts it is 1, for
2718 *		deletions it's -1. 0 for plain searches
2719 * @cow:	boolean should CoW operations be performed. Must always be 1
2720 *		when modifying the tree.
2721 *
2722 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2723 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2724 *
2725 * If @key is found, 0 is returned and you can find the item in the leaf level
2726 * of the path (level 0)
2727 *
2728 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2729 * points to the slot where it should be inserted
2730 *
2731 * If an error is encountered while searching the tree a negative error number
2732 * is returned
2733 */
2734int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2735		      const struct btrfs_key *key, struct btrfs_path *p,
2736		      int ins_len, int cow)
2737{
2738	struct extent_buffer *b;
2739	int slot;
2740	int ret;
2741	int err;
2742	int level;
2743	int lowest_unlock = 1;
 
2744	/* everything at write_lock_level or lower must be write locked */
2745	int write_lock_level = 0;
2746	u8 lowest_level = 0;
2747	int min_write_lock_level;
2748	int prev_cmp;
2749
2750	lowest_level = p->lowest_level;
2751	WARN_ON(lowest_level && ins_len > 0);
2752	WARN_ON(p->nodes[0] != NULL);
2753	BUG_ON(!cow && ins_len);
2754
2755	if (ins_len < 0) {
2756		lowest_unlock = 2;
2757
2758		/* when we are removing items, we might have to go up to level
2759		 * two as we update tree pointers  Make sure we keep write
2760		 * for those levels as well
2761		 */
2762		write_lock_level = 2;
2763	} else if (ins_len > 0) {
2764		/*
2765		 * for inserting items, make sure we have a write lock on
2766		 * level 1 so we can update keys
2767		 */
2768		write_lock_level = 1;
2769	}
2770
2771	if (!cow)
2772		write_lock_level = -1;
2773
2774	if (cow && (p->keep_locks || p->lowest_level))
2775		write_lock_level = BTRFS_MAX_LEVEL;
2776
2777	min_write_lock_level = write_lock_level;
2778
2779again:
2780	prev_cmp = -1;
2781	b = btrfs_search_slot_get_root(root, p, write_lock_level);
2782	if (IS_ERR(b)) {
2783		ret = PTR_ERR(b);
2784		goto done;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2785	}
 
 
 
2786
2787	while (b) {
2788		level = btrfs_header_level(b);
2789
2790		/*
2791		 * setup the path here so we can release it under lock
2792		 * contention with the cow code
2793		 */
2794		if (cow) {
2795			bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2796
2797			/*
2798			 * if we don't really need to cow this block
2799			 * then we don't want to set the path blocking,
2800			 * so we test it here
2801			 */
2802			if (!should_cow_block(trans, root, b)) {
2803				trans->dirty = true;
2804				goto cow_done;
2805			}
2806
2807			/*
2808			 * must have write locks on this node and the
2809			 * parent
2810			 */
2811			if (level > write_lock_level ||
2812			    (level + 1 > write_lock_level &&
2813			    level + 1 < BTRFS_MAX_LEVEL &&
2814			    p->nodes[level + 1])) {
2815				write_lock_level = level + 1;
2816				btrfs_release_path(p);
2817				goto again;
2818			}
2819
2820			btrfs_set_path_blocking(p);
2821			if (last_level)
2822				err = btrfs_cow_block(trans, root, b, NULL, 0,
2823						      &b);
2824			else
2825				err = btrfs_cow_block(trans, root, b,
2826						      p->nodes[level + 1],
2827						      p->slots[level + 1], &b);
2828			if (err) {
2829				ret = err;
2830				goto done;
2831			}
2832		}
2833cow_done:
2834		p->nodes[level] = b;
2835		/*
2836		 * Leave path with blocking locks to avoid massive
2837		 * lock context switch, this is made on purpose.
2838		 */
2839
2840		/*
2841		 * we have a lock on b and as long as we aren't changing
2842		 * the tree, there is no way to for the items in b to change.
2843		 * It is safe to drop the lock on our parent before we
2844		 * go through the expensive btree search on b.
2845		 *
2846		 * If we're inserting or deleting (ins_len != 0), then we might
2847		 * be changing slot zero, which may require changing the parent.
2848		 * So, we can't drop the lock until after we know which slot
2849		 * we're operating on.
2850		 */
2851		if (!ins_len && !p->keep_locks) {
2852			int u = level + 1;
2853
2854			if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2855				btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2856				p->locks[u] = 0;
2857			}
2858		}
2859
2860		ret = key_search(b, key, level, &prev_cmp, &slot);
2861		if (ret < 0)
2862			goto done;
2863
2864		if (level != 0) {
2865			int dec = 0;
2866			if (ret && slot > 0) {
2867				dec = 1;
2868				slot -= 1;
2869			}
2870			p->slots[level] = slot;
2871			err = setup_nodes_for_search(trans, root, p, b, level,
2872					     ins_len, &write_lock_level);
2873			if (err == -EAGAIN)
2874				goto again;
2875			if (err) {
2876				ret = err;
2877				goto done;
2878			}
2879			b = p->nodes[level];
2880			slot = p->slots[level];
2881
2882			/*
2883			 * slot 0 is special, if we change the key
2884			 * we have to update the parent pointer
2885			 * which means we must have a write lock
2886			 * on the parent
2887			 */
2888			if (slot == 0 && ins_len &&
2889			    write_lock_level < level + 1) {
2890				write_lock_level = level + 1;
2891				btrfs_release_path(p);
2892				goto again;
2893			}
2894
2895			unlock_up(p, level, lowest_unlock,
2896				  min_write_lock_level, &write_lock_level);
2897
2898			if (level == lowest_level) {
2899				if (dec)
2900					p->slots[level]++;
2901				goto done;
2902			}
2903
2904			err = read_block_for_search(root, p, &b, level,
2905						    slot, key);
2906			if (err == -EAGAIN)
2907				goto again;
2908			if (err) {
2909				ret = err;
2910				goto done;
2911			}
2912
2913			if (!p->skip_locking) {
2914				level = btrfs_header_level(b);
2915				if (level <= write_lock_level) {
2916					if (!btrfs_try_tree_write_lock(b)) {
 
2917						btrfs_set_path_blocking(p);
2918						btrfs_tree_lock(b);
 
 
2919					}
2920					p->locks[level] = BTRFS_WRITE_LOCK;
2921				} else {
2922					if (!btrfs_tree_read_lock_atomic(b)) {
 
2923						btrfs_set_path_blocking(p);
2924						btrfs_tree_read_lock(b);
 
 
2925					}
2926					p->locks[level] = BTRFS_READ_LOCK;
2927				}
2928				p->nodes[level] = b;
2929			}
2930		} else {
2931			p->slots[level] = slot;
2932			if (ins_len > 0 &&
2933			    btrfs_leaf_free_space(b) < ins_len) {
2934				if (write_lock_level < 1) {
2935					write_lock_level = 1;
2936					btrfs_release_path(p);
2937					goto again;
2938				}
2939
2940				btrfs_set_path_blocking(p);
2941				err = split_leaf(trans, root, key,
2942						 p, ins_len, ret == 0);
 
2943
2944				BUG_ON(err > 0);
2945				if (err) {
2946					ret = err;
2947					goto done;
2948				}
2949			}
2950			if (!p->search_for_split)
2951				unlock_up(p, level, lowest_unlock,
2952					  min_write_lock_level, NULL);
2953			goto done;
2954		}
2955	}
2956	ret = 1;
2957done:
2958	/*
2959	 * we don't really know what they plan on doing with the path
2960	 * from here on, so for now just mark it as blocking
2961	 */
2962	if (!p->leave_spinning)
2963		btrfs_set_path_blocking(p);
2964	if (ret < 0 && !p->skip_release_on_error)
2965		btrfs_release_path(p);
2966	return ret;
2967}
2968
2969/*
2970 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2971 * current state of the tree together with the operations recorded in the tree
2972 * modification log to search for the key in a previous version of this tree, as
2973 * denoted by the time_seq parameter.
2974 *
2975 * Naturally, there is no support for insert, delete or cow operations.
2976 *
2977 * The resulting path and return value will be set up as if we called
2978 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2979 */
2980int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2981			  struct btrfs_path *p, u64 time_seq)
2982{
2983	struct btrfs_fs_info *fs_info = root->fs_info;
2984	struct extent_buffer *b;
2985	int slot;
2986	int ret;
2987	int err;
2988	int level;
2989	int lowest_unlock = 1;
2990	u8 lowest_level = 0;
2991	int prev_cmp = -1;
2992
2993	lowest_level = p->lowest_level;
2994	WARN_ON(p->nodes[0] != NULL);
2995
2996	if (p->search_commit_root) {
2997		BUG_ON(time_seq);
2998		return btrfs_search_slot(NULL, root, key, p, 0, 0);
2999	}
3000
3001again:
3002	b = get_old_root(root, time_seq);
3003	if (!b) {
3004		ret = -EIO;
3005		goto done;
3006	}
3007	level = btrfs_header_level(b);
3008	p->locks[level] = BTRFS_READ_LOCK;
3009
3010	while (b) {
3011		level = btrfs_header_level(b);
3012		p->nodes[level] = b;
 
3013
3014		/*
3015		 * we have a lock on b and as long as we aren't changing
3016		 * the tree, there is no way to for the items in b to change.
3017		 * It is safe to drop the lock on our parent before we
3018		 * go through the expensive btree search on b.
3019		 */
3020		btrfs_unlock_up_safe(p, level + 1);
3021
3022		/*
3023		 * Since we can unwind ebs we want to do a real search every
3024		 * time.
3025		 */
3026		prev_cmp = -1;
3027		ret = key_search(b, key, level, &prev_cmp, &slot);
3028		if (ret < 0)
3029			goto done;
3030
3031		if (level != 0) {
3032			int dec = 0;
3033			if (ret && slot > 0) {
3034				dec = 1;
3035				slot -= 1;
3036			}
3037			p->slots[level] = slot;
3038			unlock_up(p, level, lowest_unlock, 0, NULL);
3039
3040			if (level == lowest_level) {
3041				if (dec)
3042					p->slots[level]++;
3043				goto done;
3044			}
3045
3046			err = read_block_for_search(root, p, &b, level,
3047						    slot, key);
3048			if (err == -EAGAIN)
3049				goto again;
3050			if (err) {
3051				ret = err;
3052				goto done;
3053			}
3054
3055			level = btrfs_header_level(b);
3056			if (!btrfs_tree_read_lock_atomic(b)) {
 
3057				btrfs_set_path_blocking(p);
3058				btrfs_tree_read_lock(b);
 
 
3059			}
3060			b = tree_mod_log_rewind(fs_info, p, b, time_seq);
3061			if (!b) {
3062				ret = -ENOMEM;
3063				goto done;
3064			}
3065			p->locks[level] = BTRFS_READ_LOCK;
3066			p->nodes[level] = b;
3067		} else {
3068			p->slots[level] = slot;
3069			unlock_up(p, level, lowest_unlock, 0, NULL);
3070			goto done;
3071		}
3072	}
3073	ret = 1;
3074done:
3075	if (!p->leave_spinning)
3076		btrfs_set_path_blocking(p);
3077	if (ret < 0)
3078		btrfs_release_path(p);
3079
3080	return ret;
3081}
3082
3083/*
3084 * helper to use instead of search slot if no exact match is needed but
3085 * instead the next or previous item should be returned.
3086 * When find_higher is true, the next higher item is returned, the next lower
3087 * otherwise.
3088 * When return_any and find_higher are both true, and no higher item is found,
3089 * return the next lower instead.
3090 * When return_any is true and find_higher is false, and no lower item is found,
3091 * return the next higher instead.
3092 * It returns 0 if any item is found, 1 if none is found (tree empty), and
3093 * < 0 on error
3094 */
3095int btrfs_search_slot_for_read(struct btrfs_root *root,
3096			       const struct btrfs_key *key,
3097			       struct btrfs_path *p, int find_higher,
3098			       int return_any)
3099{
3100	int ret;
3101	struct extent_buffer *leaf;
3102
3103again:
3104	ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
3105	if (ret <= 0)
3106		return ret;
3107	/*
3108	 * a return value of 1 means the path is at the position where the
3109	 * item should be inserted. Normally this is the next bigger item,
3110	 * but in case the previous item is the last in a leaf, path points
3111	 * to the first free slot in the previous leaf, i.e. at an invalid
3112	 * item.
3113	 */
3114	leaf = p->nodes[0];
3115
3116	if (find_higher) {
3117		if (p->slots[0] >= btrfs_header_nritems(leaf)) {
3118			ret = btrfs_next_leaf(root, p);
3119			if (ret <= 0)
3120				return ret;
3121			if (!return_any)
3122				return 1;
3123			/*
3124			 * no higher item found, return the next
3125			 * lower instead
3126			 */
3127			return_any = 0;
3128			find_higher = 0;
3129			btrfs_release_path(p);
3130			goto again;
3131		}
3132	} else {
3133		if (p->slots[0] == 0) {
3134			ret = btrfs_prev_leaf(root, p);
3135			if (ret < 0)
3136				return ret;
3137			if (!ret) {
3138				leaf = p->nodes[0];
3139				if (p->slots[0] == btrfs_header_nritems(leaf))
3140					p->slots[0]--;
3141				return 0;
3142			}
3143			if (!return_any)
3144				return 1;
3145			/*
3146			 * no lower item found, return the next
3147			 * higher instead
3148			 */
3149			return_any = 0;
3150			find_higher = 1;
3151			btrfs_release_path(p);
3152			goto again;
3153		} else {
3154			--p->slots[0];
3155		}
3156	}
3157	return 0;
3158}
3159
3160/*
3161 * adjust the pointers going up the tree, starting at level
3162 * making sure the right key of each node is points to 'key'.
3163 * This is used after shifting pointers to the left, so it stops
3164 * fixing up pointers when a given leaf/node is not in slot 0 of the
3165 * higher levels
3166 *
3167 */
3168static void fixup_low_keys(struct btrfs_path *path,
 
3169			   struct btrfs_disk_key *key, int level)
3170{
3171	int i;
3172	struct extent_buffer *t;
3173	int ret;
3174
3175	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
3176		int tslot = path->slots[i];
3177
3178		if (!path->nodes[i])
3179			break;
3180		t = path->nodes[i];
3181		ret = tree_mod_log_insert_key(t, tslot, MOD_LOG_KEY_REPLACE,
3182				GFP_ATOMIC);
3183		BUG_ON(ret < 0);
3184		btrfs_set_node_key(t, key, tslot);
3185		btrfs_mark_buffer_dirty(path->nodes[i]);
3186		if (tslot != 0)
3187			break;
3188	}
3189}
3190
3191/*
3192 * update item key.
3193 *
3194 * This function isn't completely safe. It's the caller's responsibility
3195 * that the new key won't break the order
3196 */
3197void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
3198			     struct btrfs_path *path,
3199			     const struct btrfs_key *new_key)
3200{
3201	struct btrfs_disk_key disk_key;
3202	struct extent_buffer *eb;
3203	int slot;
3204
3205	eb = path->nodes[0];
3206	slot = path->slots[0];
3207	if (slot > 0) {
3208		btrfs_item_key(eb, &disk_key, slot - 1);
3209		if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
3210			btrfs_crit(fs_info,
3211		"slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3212				   slot, btrfs_disk_key_objectid(&disk_key),
3213				   btrfs_disk_key_type(&disk_key),
3214				   btrfs_disk_key_offset(&disk_key),
3215				   new_key->objectid, new_key->type,
3216				   new_key->offset);
3217			btrfs_print_leaf(eb);
3218			BUG();
3219		}
3220	}
3221	if (slot < btrfs_header_nritems(eb) - 1) {
3222		btrfs_item_key(eb, &disk_key, slot + 1);
3223		if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
3224			btrfs_crit(fs_info,
3225		"slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3226				   slot, btrfs_disk_key_objectid(&disk_key),
3227				   btrfs_disk_key_type(&disk_key),
3228				   btrfs_disk_key_offset(&disk_key),
3229				   new_key->objectid, new_key->type,
3230				   new_key->offset);
3231			btrfs_print_leaf(eb);
3232			BUG();
3233		}
3234	}
3235
3236	btrfs_cpu_key_to_disk(&disk_key, new_key);
3237	btrfs_set_item_key(eb, &disk_key, slot);
3238	btrfs_mark_buffer_dirty(eb);
3239	if (slot == 0)
3240		fixup_low_keys(path, &disk_key, 1);
3241}
3242
3243/*
3244 * try to push data from one node into the next node left in the
3245 * tree.
3246 *
3247 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
3248 * error, and > 0 if there was no room in the left hand block.
3249 */
3250static int push_node_left(struct btrfs_trans_handle *trans,
3251			  struct extent_buffer *dst,
3252			  struct extent_buffer *src, int empty)
3253{
3254	struct btrfs_fs_info *fs_info = trans->fs_info;
3255	int push_items = 0;
3256	int src_nritems;
3257	int dst_nritems;
3258	int ret = 0;
3259
3260	src_nritems = btrfs_header_nritems(src);
3261	dst_nritems = btrfs_header_nritems(dst);
3262	push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3263	WARN_ON(btrfs_header_generation(src) != trans->transid);
3264	WARN_ON(btrfs_header_generation(dst) != trans->transid);
3265
3266	if (!empty && src_nritems <= 8)
3267		return 1;
3268
3269	if (push_items <= 0)
3270		return 1;
3271
3272	if (empty) {
3273		push_items = min(src_nritems, push_items);
3274		if (push_items < src_nritems) {
3275			/* leave at least 8 pointers in the node if
3276			 * we aren't going to empty it
3277			 */
3278			if (src_nritems - push_items < 8) {
3279				if (push_items <= 8)
3280					return 1;
3281				push_items -= 8;
3282			}
3283		}
3284	} else
3285		push_items = min(src_nritems - 8, push_items);
3286
3287	ret = tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
 
3288	if (ret) {
3289		btrfs_abort_transaction(trans, ret);
3290		return ret;
3291	}
3292	copy_extent_buffer(dst, src,
3293			   btrfs_node_key_ptr_offset(dst_nritems),
3294			   btrfs_node_key_ptr_offset(0),
3295			   push_items * sizeof(struct btrfs_key_ptr));
3296
3297	if (push_items < src_nritems) {
3298		/*
3299		 * Don't call tree_mod_log_insert_move here, key removal was
3300		 * already fully logged by tree_mod_log_eb_copy above.
3301		 */
3302		memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3303				      btrfs_node_key_ptr_offset(push_items),
3304				      (src_nritems - push_items) *
3305				      sizeof(struct btrfs_key_ptr));
3306	}
3307	btrfs_set_header_nritems(src, src_nritems - push_items);
3308	btrfs_set_header_nritems(dst, dst_nritems + push_items);
3309	btrfs_mark_buffer_dirty(src);
3310	btrfs_mark_buffer_dirty(dst);
3311
3312	return ret;
3313}
3314
3315/*
3316 * try to push data from one node into the next node right in the
3317 * tree.
3318 *
3319 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3320 * error, and > 0 if there was no room in the right hand block.
3321 *
3322 * this will  only push up to 1/2 the contents of the left node over
3323 */
3324static int balance_node_right(struct btrfs_trans_handle *trans,
 
3325			      struct extent_buffer *dst,
3326			      struct extent_buffer *src)
3327{
3328	struct btrfs_fs_info *fs_info = trans->fs_info;
3329	int push_items = 0;
3330	int max_push;
3331	int src_nritems;
3332	int dst_nritems;
3333	int ret = 0;
3334
3335	WARN_ON(btrfs_header_generation(src) != trans->transid);
3336	WARN_ON(btrfs_header_generation(dst) != trans->transid);
3337
3338	src_nritems = btrfs_header_nritems(src);
3339	dst_nritems = btrfs_header_nritems(dst);
3340	push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3341	if (push_items <= 0)
3342		return 1;
3343
3344	if (src_nritems < 4)
3345		return 1;
3346
3347	max_push = src_nritems / 2 + 1;
3348	/* don't try to empty the node */
3349	if (max_push >= src_nritems)
3350		return 1;
3351
3352	if (max_push < push_items)
3353		push_items = max_push;
3354
3355	ret = tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
3356	BUG_ON(ret < 0);
3357	memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3358				      btrfs_node_key_ptr_offset(0),
3359				      (dst_nritems) *
3360				      sizeof(struct btrfs_key_ptr));
3361
3362	ret = tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
3363				   push_items);
3364	if (ret) {
3365		btrfs_abort_transaction(trans, ret);
3366		return ret;
3367	}
3368	copy_extent_buffer(dst, src,
3369			   btrfs_node_key_ptr_offset(0),
3370			   btrfs_node_key_ptr_offset(src_nritems - push_items),
3371			   push_items * sizeof(struct btrfs_key_ptr));
3372
3373	btrfs_set_header_nritems(src, src_nritems - push_items);
3374	btrfs_set_header_nritems(dst, dst_nritems + push_items);
3375
3376	btrfs_mark_buffer_dirty(src);
3377	btrfs_mark_buffer_dirty(dst);
3378
3379	return ret;
3380}
3381
3382/*
3383 * helper function to insert a new root level in the tree.
3384 * A new node is allocated, and a single item is inserted to
3385 * point to the existing root
3386 *
3387 * returns zero on success or < 0 on failure.
3388 */
3389static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3390			   struct btrfs_root *root,
3391			   struct btrfs_path *path, int level)
3392{
3393	struct btrfs_fs_info *fs_info = root->fs_info;
3394	u64 lower_gen;
3395	struct extent_buffer *lower;
3396	struct extent_buffer *c;
3397	struct extent_buffer *old;
3398	struct btrfs_disk_key lower_key;
3399	int ret;
3400
3401	BUG_ON(path->nodes[level]);
3402	BUG_ON(path->nodes[level-1] != root->node);
3403
3404	lower = path->nodes[level-1];
3405	if (level == 1)
3406		btrfs_item_key(lower, &lower_key, 0);
3407	else
3408		btrfs_node_key(lower, &lower_key, 0);
3409
3410	c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
3411					 root->node->start, 0);
3412	if (IS_ERR(c))
3413		return PTR_ERR(c);
3414
3415	root_add_used(root, fs_info->nodesize);
3416
 
3417	btrfs_set_header_nritems(c, 1);
 
 
 
 
 
 
 
 
 
 
 
 
3418	btrfs_set_node_key(c, &lower_key, 0);
3419	btrfs_set_node_blockptr(c, 0, lower->start);
3420	lower_gen = btrfs_header_generation(lower);
3421	WARN_ON(lower_gen != trans->transid);
3422
3423	btrfs_set_node_ptr_generation(c, 0, lower_gen);
3424
3425	btrfs_mark_buffer_dirty(c);
3426
3427	old = root->node;
3428	ret = tree_mod_log_insert_root(root->node, c, 0);
3429	BUG_ON(ret < 0);
3430	rcu_assign_pointer(root->node, c);
3431
3432	/* the super has an extra ref to root->node */
3433	free_extent_buffer(old);
3434
3435	add_root_to_dirty_list(root);
3436	extent_buffer_get(c);
3437	path->nodes[level] = c;
3438	path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
3439	path->slots[level] = 0;
3440	return 0;
3441}
3442
3443/*
3444 * worker function to insert a single pointer in a node.
3445 * the node should have enough room for the pointer already
3446 *
3447 * slot and level indicate where you want the key to go, and
3448 * blocknr is the block the key points to.
3449 */
3450static void insert_ptr(struct btrfs_trans_handle *trans,
3451		       struct btrfs_path *path,
3452		       struct btrfs_disk_key *key, u64 bytenr,
3453		       int slot, int level)
3454{
3455	struct extent_buffer *lower;
3456	int nritems;
3457	int ret;
3458
3459	BUG_ON(!path->nodes[level]);
3460	btrfs_assert_tree_locked(path->nodes[level]);
3461	lower = path->nodes[level];
3462	nritems = btrfs_header_nritems(lower);
3463	BUG_ON(slot > nritems);
3464	BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
3465	if (slot != nritems) {
3466		if (level) {
3467			ret = tree_mod_log_insert_move(lower, slot + 1, slot,
3468					nritems - slot);
3469			BUG_ON(ret < 0);
3470		}
3471		memmove_extent_buffer(lower,
3472			      btrfs_node_key_ptr_offset(slot + 1),
3473			      btrfs_node_key_ptr_offset(slot),
3474			      (nritems - slot) * sizeof(struct btrfs_key_ptr));
3475	}
3476	if (level) {
3477		ret = tree_mod_log_insert_key(lower, slot, MOD_LOG_KEY_ADD,
3478				GFP_NOFS);
3479		BUG_ON(ret < 0);
3480	}
3481	btrfs_set_node_key(lower, key, slot);
3482	btrfs_set_node_blockptr(lower, slot, bytenr);
3483	WARN_ON(trans->transid == 0);
3484	btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3485	btrfs_set_header_nritems(lower, nritems + 1);
3486	btrfs_mark_buffer_dirty(lower);
3487}
3488
3489/*
3490 * split the node at the specified level in path in two.
3491 * The path is corrected to point to the appropriate node after the split
3492 *
3493 * Before splitting this tries to make some room in the node by pushing
3494 * left and right, if either one works, it returns right away.
3495 *
3496 * returns 0 on success and < 0 on failure
3497 */
3498static noinline int split_node(struct btrfs_trans_handle *trans,
3499			       struct btrfs_root *root,
3500			       struct btrfs_path *path, int level)
3501{
3502	struct btrfs_fs_info *fs_info = root->fs_info;
3503	struct extent_buffer *c;
3504	struct extent_buffer *split;
3505	struct btrfs_disk_key disk_key;
3506	int mid;
3507	int ret;
3508	u32 c_nritems;
3509
3510	c = path->nodes[level];
3511	WARN_ON(btrfs_header_generation(c) != trans->transid);
3512	if (c == root->node) {
3513		/*
3514		 * trying to split the root, lets make a new one
3515		 *
3516		 * tree mod log: We don't log_removal old root in
3517		 * insert_new_root, because that root buffer will be kept as a
3518		 * normal node. We are going to log removal of half of the
3519		 * elements below with tree_mod_log_eb_copy. We're holding a
3520		 * tree lock on the buffer, which is why we cannot race with
3521		 * other tree_mod_log users.
3522		 */
3523		ret = insert_new_root(trans, root, path, level + 1);
3524		if (ret)
3525			return ret;
3526	} else {
3527		ret = push_nodes_for_insert(trans, root, path, level);
3528		c = path->nodes[level];
3529		if (!ret && btrfs_header_nritems(c) <
3530		    BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3531			return 0;
3532		if (ret < 0)
3533			return ret;
3534	}
3535
3536	c_nritems = btrfs_header_nritems(c);
3537	mid = (c_nritems + 1) / 2;
3538	btrfs_node_key(c, &disk_key, mid);
3539
3540	split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
3541					     c->start, 0);
3542	if (IS_ERR(split))
3543		return PTR_ERR(split);
3544
3545	root_add_used(root, fs_info->nodesize);
3546	ASSERT(btrfs_header_level(c) == level);
3547
3548	ret = tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
 
 
 
 
 
 
 
 
 
 
 
 
 
3549	if (ret) {
3550		btrfs_abort_transaction(trans, ret);
3551		return ret;
3552	}
3553	copy_extent_buffer(split, c,
3554			   btrfs_node_key_ptr_offset(0),
3555			   btrfs_node_key_ptr_offset(mid),
3556			   (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3557	btrfs_set_header_nritems(split, c_nritems - mid);
3558	btrfs_set_header_nritems(c, mid);
3559	ret = 0;
3560
3561	btrfs_mark_buffer_dirty(c);
3562	btrfs_mark_buffer_dirty(split);
3563
3564	insert_ptr(trans, path, &disk_key, split->start,
3565		   path->slots[level + 1] + 1, level + 1);
3566
3567	if (path->slots[level] >= mid) {
3568		path->slots[level] -= mid;
3569		btrfs_tree_unlock(c);
3570		free_extent_buffer(c);
3571		path->nodes[level] = split;
3572		path->slots[level + 1] += 1;
3573	} else {
3574		btrfs_tree_unlock(split);
3575		free_extent_buffer(split);
3576	}
3577	return ret;
3578}
3579
3580/*
3581 * how many bytes are required to store the items in a leaf.  start
3582 * and nr indicate which items in the leaf to check.  This totals up the
3583 * space used both by the item structs and the item data
3584 */
3585static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3586{
3587	struct btrfs_item *start_item;
3588	struct btrfs_item *end_item;
3589	struct btrfs_map_token token;
3590	int data_len;
3591	int nritems = btrfs_header_nritems(l);
3592	int end = min(nritems, start + nr) - 1;
3593
3594	if (!nr)
3595		return 0;
3596	btrfs_init_map_token(&token, l);
3597	start_item = btrfs_item_nr(start);
3598	end_item = btrfs_item_nr(end);
3599	data_len = btrfs_token_item_offset(l, start_item, &token) +
3600		btrfs_token_item_size(l, start_item, &token);
3601	data_len = data_len - btrfs_token_item_offset(l, end_item, &token);
3602	data_len += sizeof(struct btrfs_item) * nr;
3603	WARN_ON(data_len < 0);
3604	return data_len;
3605}
3606
3607/*
3608 * The space between the end of the leaf items and
3609 * the start of the leaf data.  IOW, how much room
3610 * the leaf has left for both items and data
3611 */
3612noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
 
3613{
3614	struct btrfs_fs_info *fs_info = leaf->fs_info;
3615	int nritems = btrfs_header_nritems(leaf);
3616	int ret;
3617
3618	ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3619	if (ret < 0) {
3620		btrfs_crit(fs_info,
3621			   "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3622			   ret,
3623			   (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3624			   leaf_space_used(leaf, 0, nritems), nritems);
3625	}
3626	return ret;
3627}
3628
3629/*
3630 * min slot controls the lowest index we're willing to push to the
3631 * right.  We'll push up to and including min_slot, but no lower
3632 */
3633static noinline int __push_leaf_right(struct btrfs_path *path,
 
 
3634				      int data_size, int empty,
3635				      struct extent_buffer *right,
3636				      int free_space, u32 left_nritems,
3637				      u32 min_slot)
3638{
3639	struct btrfs_fs_info *fs_info = right->fs_info;
3640	struct extent_buffer *left = path->nodes[0];
3641	struct extent_buffer *upper = path->nodes[1];
3642	struct btrfs_map_token token;
3643	struct btrfs_disk_key disk_key;
3644	int slot;
3645	u32 i;
3646	int push_space = 0;
3647	int push_items = 0;
3648	struct btrfs_item *item;
3649	u32 nr;
3650	u32 right_nritems;
3651	u32 data_end;
3652	u32 this_item_size;
3653
 
 
3654	if (empty)
3655		nr = 0;
3656	else
3657		nr = max_t(u32, 1, min_slot);
3658
3659	if (path->slots[0] >= left_nritems)
3660		push_space += data_size;
3661
3662	slot = path->slots[1];
3663	i = left_nritems - 1;
3664	while (i >= nr) {
3665		item = btrfs_item_nr(i);
3666
3667		if (!empty && push_items > 0) {
3668			if (path->slots[0] > i)
3669				break;
3670			if (path->slots[0] == i) {
3671				int space = btrfs_leaf_free_space(left);
3672
3673				if (space + push_space * 2 > free_space)
3674					break;
3675			}
3676		}
3677
3678		if (path->slots[0] == i)
3679			push_space += data_size;
3680
3681		this_item_size = btrfs_item_size(left, item);
3682		if (this_item_size + sizeof(*item) + push_space > free_space)
3683			break;
3684
3685		push_items++;
3686		push_space += this_item_size + sizeof(*item);
3687		if (i == 0)
3688			break;
3689		i--;
3690	}
3691
3692	if (push_items == 0)
3693		goto out_unlock;
3694
3695	WARN_ON(!empty && push_items == left_nritems);
3696
3697	/* push left to right */
3698	right_nritems = btrfs_header_nritems(right);
3699
3700	push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3701	push_space -= leaf_data_end(left);
3702
3703	/* make room in the right data area */
3704	data_end = leaf_data_end(right);
3705	memmove_extent_buffer(right,
3706			      BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
3707			      BTRFS_LEAF_DATA_OFFSET + data_end,
3708			      BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3709
3710	/* copy from the left data area */
3711	copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
3712		     BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3713		     BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
3714		     push_space);
3715
3716	memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3717			      btrfs_item_nr_offset(0),
3718			      right_nritems * sizeof(struct btrfs_item));
3719
3720	/* copy the items from left to right */
3721	copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3722		   btrfs_item_nr_offset(left_nritems - push_items),
3723		   push_items * sizeof(struct btrfs_item));
3724
3725	/* update the item pointers */
3726	btrfs_init_map_token(&token, right);
3727	right_nritems += push_items;
3728	btrfs_set_header_nritems(right, right_nritems);
3729	push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3730	for (i = 0; i < right_nritems; i++) {
3731		item = btrfs_item_nr(i);
3732		push_space -= btrfs_token_item_size(right, item, &token);
3733		btrfs_set_token_item_offset(right, item, push_space, &token);
3734	}
3735
3736	left_nritems -= push_items;
3737	btrfs_set_header_nritems(left, left_nritems);
3738
3739	if (left_nritems)
3740		btrfs_mark_buffer_dirty(left);
3741	else
3742		btrfs_clean_tree_block(left);
3743
3744	btrfs_mark_buffer_dirty(right);
3745
3746	btrfs_item_key(right, &disk_key, 0);
3747	btrfs_set_node_key(upper, &disk_key, slot + 1);
3748	btrfs_mark_buffer_dirty(upper);
3749
3750	/* then fixup the leaf pointer in the path */
3751	if (path->slots[0] >= left_nritems) {
3752		path->slots[0] -= left_nritems;
3753		if (btrfs_header_nritems(path->nodes[0]) == 0)
3754			btrfs_clean_tree_block(path->nodes[0]);
3755		btrfs_tree_unlock(path->nodes[0]);
3756		free_extent_buffer(path->nodes[0]);
3757		path->nodes[0] = right;
3758		path->slots[1] += 1;
3759	} else {
3760		btrfs_tree_unlock(right);
3761		free_extent_buffer(right);
3762	}
3763	return 0;
3764
3765out_unlock:
3766	btrfs_tree_unlock(right);
3767	free_extent_buffer(right);
3768	return 1;
3769}
3770
3771/*
3772 * push some data in the path leaf to the right, trying to free up at
3773 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3774 *
3775 * returns 1 if the push failed because the other node didn't have enough
3776 * room, 0 if everything worked out and < 0 if there were major errors.
3777 *
3778 * this will push starting from min_slot to the end of the leaf.  It won't
3779 * push any slot lower than min_slot
3780 */
3781static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3782			   *root, struct btrfs_path *path,
3783			   int min_data_size, int data_size,
3784			   int empty, u32 min_slot)
3785{
3786	struct extent_buffer *left = path->nodes[0];
3787	struct extent_buffer *right;
3788	struct extent_buffer *upper;
3789	int slot;
3790	int free_space;
3791	u32 left_nritems;
3792	int ret;
3793
3794	if (!path->nodes[1])
3795		return 1;
3796
3797	slot = path->slots[1];
3798	upper = path->nodes[1];
3799	if (slot >= btrfs_header_nritems(upper) - 1)
3800		return 1;
3801
3802	btrfs_assert_tree_locked(path->nodes[1]);
3803
3804	right = btrfs_read_node_slot(upper, slot + 1);
3805	/*
3806	 * slot + 1 is not valid or we fail to read the right node,
3807	 * no big deal, just return.
3808	 */
3809	if (IS_ERR(right))
3810		return 1;
3811
3812	btrfs_tree_lock(right);
3813	btrfs_set_lock_blocking_write(right);
3814
3815	free_space = btrfs_leaf_free_space(right);
3816	if (free_space < data_size)
3817		goto out_unlock;
3818
3819	/* cow and double check */
3820	ret = btrfs_cow_block(trans, root, right, upper,
3821			      slot + 1, &right);
3822	if (ret)
3823		goto out_unlock;
3824
3825	free_space = btrfs_leaf_free_space(right);
3826	if (free_space < data_size)
3827		goto out_unlock;
3828
3829	left_nritems = btrfs_header_nritems(left);
3830	if (left_nritems == 0)
3831		goto out_unlock;
3832
3833	if (path->slots[0] == left_nritems && !empty) {
3834		/* Key greater than all keys in the leaf, right neighbor has
3835		 * enough room for it and we're not emptying our leaf to delete
3836		 * it, therefore use right neighbor to insert the new item and
3837		 * no need to touch/dirty our left leaf. */
3838		btrfs_tree_unlock(left);
3839		free_extent_buffer(left);
3840		path->nodes[0] = right;
3841		path->slots[0] = 0;
3842		path->slots[1]++;
3843		return 0;
3844	}
3845
3846	return __push_leaf_right(path, min_data_size, empty,
3847				right, free_space, left_nritems, min_slot);
3848out_unlock:
3849	btrfs_tree_unlock(right);
3850	free_extent_buffer(right);
3851	return 1;
3852}
3853
3854/*
3855 * push some data in the path leaf to the left, trying to free up at
3856 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3857 *
3858 * max_slot can put a limit on how far into the leaf we'll push items.  The
3859 * item at 'max_slot' won't be touched.  Use (u32)-1 to make us do all the
3860 * items
3861 */
3862static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
 
 
3863				     int empty, struct extent_buffer *left,
3864				     int free_space, u32 right_nritems,
3865				     u32 max_slot)
3866{
3867	struct btrfs_fs_info *fs_info = left->fs_info;
3868	struct btrfs_disk_key disk_key;
3869	struct extent_buffer *right = path->nodes[0];
3870	int i;
3871	int push_space = 0;
3872	int push_items = 0;
3873	struct btrfs_item *item;
3874	u32 old_left_nritems;
3875	u32 nr;
3876	int ret = 0;
3877	u32 this_item_size;
3878	u32 old_left_item_size;
3879	struct btrfs_map_token token;
3880
 
 
3881	if (empty)
3882		nr = min(right_nritems, max_slot);
3883	else
3884		nr = min(right_nritems - 1, max_slot);
3885
3886	for (i = 0; i < nr; i++) {
3887		item = btrfs_item_nr(i);
3888
3889		if (!empty && push_items > 0) {
3890			if (path->slots[0] < i)
3891				break;
3892			if (path->slots[0] == i) {
3893				int space = btrfs_leaf_free_space(right);
3894
3895				if (space + push_space * 2 > free_space)
3896					break;
3897			}
3898		}
3899
3900		if (path->slots[0] == i)
3901			push_space += data_size;
3902
3903		this_item_size = btrfs_item_size(right, item);
3904		if (this_item_size + sizeof(*item) + push_space > free_space)
3905			break;
3906
3907		push_items++;
3908		push_space += this_item_size + sizeof(*item);
3909	}
3910
3911	if (push_items == 0) {
3912		ret = 1;
3913		goto out;
3914	}
3915	WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3916
3917	/* push data from right to left */
3918	copy_extent_buffer(left, right,
3919			   btrfs_item_nr_offset(btrfs_header_nritems(left)),
3920			   btrfs_item_nr_offset(0),
3921			   push_items * sizeof(struct btrfs_item));
3922
3923	push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3924		     btrfs_item_offset_nr(right, push_items - 1);
3925
3926	copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
3927		     leaf_data_end(left) - push_space,
3928		     BTRFS_LEAF_DATA_OFFSET +
3929		     btrfs_item_offset_nr(right, push_items - 1),
3930		     push_space);
3931	old_left_nritems = btrfs_header_nritems(left);
3932	BUG_ON(old_left_nritems <= 0);
3933
3934	btrfs_init_map_token(&token, left);
3935	old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3936	for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3937		u32 ioff;
3938
3939		item = btrfs_item_nr(i);
3940
3941		ioff = btrfs_token_item_offset(left, item, &token);
3942		btrfs_set_token_item_offset(left, item,
3943		      ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size),
3944		      &token);
3945	}
3946	btrfs_set_header_nritems(left, old_left_nritems + push_items);
3947
3948	/* fixup right node */
3949	if (push_items > right_nritems)
3950		WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3951		       right_nritems);
3952
3953	if (push_items < right_nritems) {
3954		push_space = btrfs_item_offset_nr(right, push_items - 1) -
3955						  leaf_data_end(right);
3956		memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
3957				      BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3958				      BTRFS_LEAF_DATA_OFFSET +
3959				      leaf_data_end(right), push_space);
3960
3961		memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3962			      btrfs_item_nr_offset(push_items),
3963			     (btrfs_header_nritems(right) - push_items) *
3964			     sizeof(struct btrfs_item));
3965	}
3966
3967	btrfs_init_map_token(&token, right);
3968	right_nritems -= push_items;
3969	btrfs_set_header_nritems(right, right_nritems);
3970	push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3971	for (i = 0; i < right_nritems; i++) {
3972		item = btrfs_item_nr(i);
3973
3974		push_space = push_space - btrfs_token_item_size(right,
3975								item, &token);
3976		btrfs_set_token_item_offset(right, item, push_space, &token);
3977	}
3978
3979	btrfs_mark_buffer_dirty(left);
3980	if (right_nritems)
3981		btrfs_mark_buffer_dirty(right);
3982	else
3983		btrfs_clean_tree_block(right);
3984
3985	btrfs_item_key(right, &disk_key, 0);
3986	fixup_low_keys(path, &disk_key, 1);
3987
3988	/* then fixup the leaf pointer in the path */
3989	if (path->slots[0] < push_items) {
3990		path->slots[0] += old_left_nritems;
3991		btrfs_tree_unlock(path->nodes[0]);
3992		free_extent_buffer(path->nodes[0]);
3993		path->nodes[0] = left;
3994		path->slots[1] -= 1;
3995	} else {
3996		btrfs_tree_unlock(left);
3997		free_extent_buffer(left);
3998		path->slots[0] -= push_items;
3999	}
4000	BUG_ON(path->slots[0] < 0);
4001	return ret;
4002out:
4003	btrfs_tree_unlock(left);
4004	free_extent_buffer(left);
4005	return ret;
4006}
4007
4008/*
4009 * push some data in the path leaf to the left, trying to free up at
4010 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
4011 *
4012 * max_slot can put a limit on how far into the leaf we'll push items.  The
4013 * item at 'max_slot' won't be touched.  Use (u32)-1 to make us push all the
4014 * items
4015 */
4016static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
4017			  *root, struct btrfs_path *path, int min_data_size,
4018			  int data_size, int empty, u32 max_slot)
4019{
4020	struct extent_buffer *right = path->nodes[0];
4021	struct extent_buffer *left;
4022	int slot;
4023	int free_space;
4024	u32 right_nritems;
4025	int ret = 0;
4026
4027	slot = path->slots[1];
4028	if (slot == 0)
4029		return 1;
4030	if (!path->nodes[1])
4031		return 1;
4032
4033	right_nritems = btrfs_header_nritems(right);
4034	if (right_nritems == 0)
4035		return 1;
4036
4037	btrfs_assert_tree_locked(path->nodes[1]);
4038
4039	left = btrfs_read_node_slot(path->nodes[1], slot - 1);
4040	/*
4041	 * slot - 1 is not valid or we fail to read the left node,
4042	 * no big deal, just return.
4043	 */
4044	if (IS_ERR(left))
4045		return 1;
4046
4047	btrfs_tree_lock(left);
4048	btrfs_set_lock_blocking_write(left);
4049
4050	free_space = btrfs_leaf_free_space(left);
4051	if (free_space < data_size) {
4052		ret = 1;
4053		goto out;
4054	}
4055
4056	/* cow and double check */
4057	ret = btrfs_cow_block(trans, root, left,
4058			      path->nodes[1], slot - 1, &left);
4059	if (ret) {
4060		/* we hit -ENOSPC, but it isn't fatal here */
4061		if (ret == -ENOSPC)
4062			ret = 1;
4063		goto out;
4064	}
4065
4066	free_space = btrfs_leaf_free_space(left);
4067	if (free_space < data_size) {
4068		ret = 1;
4069		goto out;
4070	}
4071
4072	return __push_leaf_left(path, min_data_size,
4073			       empty, left, free_space, right_nritems,
4074			       max_slot);
4075out:
4076	btrfs_tree_unlock(left);
4077	free_extent_buffer(left);
4078	return ret;
4079}
4080
4081/*
4082 * split the path's leaf in two, making sure there is at least data_size
4083 * available for the resulting leaf level of the path.
4084 */
4085static noinline void copy_for_split(struct btrfs_trans_handle *trans,
 
4086				    struct btrfs_path *path,
4087				    struct extent_buffer *l,
4088				    struct extent_buffer *right,
4089				    int slot, int mid, int nritems)
4090{
4091	struct btrfs_fs_info *fs_info = trans->fs_info;
4092	int data_copy_size;
4093	int rt_data_off;
4094	int i;
4095	struct btrfs_disk_key disk_key;
4096	struct btrfs_map_token token;
4097
 
 
4098	nritems = nritems - mid;
4099	btrfs_set_header_nritems(right, nritems);
4100	data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(l);
4101
4102	copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
4103			   btrfs_item_nr_offset(mid),
4104			   nritems * sizeof(struct btrfs_item));
4105
4106	copy_extent_buffer(right, l,
4107		     BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
4108		     data_copy_size, BTRFS_LEAF_DATA_OFFSET +
4109		     leaf_data_end(l), data_copy_size);
4110
4111	rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
 
4112
4113	btrfs_init_map_token(&token, right);
4114	for (i = 0; i < nritems; i++) {
4115		struct btrfs_item *item = btrfs_item_nr(i);
4116		u32 ioff;
4117
4118		ioff = btrfs_token_item_offset(right, item, &token);
4119		btrfs_set_token_item_offset(right, item,
4120					    ioff + rt_data_off, &token);
4121	}
4122
4123	btrfs_set_header_nritems(l, mid);
4124	btrfs_item_key(right, &disk_key, 0);
4125	insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
 
4126
4127	btrfs_mark_buffer_dirty(right);
4128	btrfs_mark_buffer_dirty(l);
4129	BUG_ON(path->slots[0] != slot);
4130
4131	if (mid <= slot) {
4132		btrfs_tree_unlock(path->nodes[0]);
4133		free_extent_buffer(path->nodes[0]);
4134		path->nodes[0] = right;
4135		path->slots[0] -= mid;
4136		path->slots[1] += 1;
4137	} else {
4138		btrfs_tree_unlock(right);
4139		free_extent_buffer(right);
4140	}
4141
4142	BUG_ON(path->slots[0] < 0);
4143}
4144
4145/*
4146 * double splits happen when we need to insert a big item in the middle
4147 * of a leaf.  A double split can leave us with 3 mostly empty leaves:
4148 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
4149 *          A                 B                 C
4150 *
4151 * We avoid this by trying to push the items on either side of our target
4152 * into the adjacent leaves.  If all goes well we can avoid the double split
4153 * completely.
4154 */
4155static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
4156					  struct btrfs_root *root,
4157					  struct btrfs_path *path,
4158					  int data_size)
4159{
4160	int ret;
4161	int progress = 0;
4162	int slot;
4163	u32 nritems;
4164	int space_needed = data_size;
4165
4166	slot = path->slots[0];
4167	if (slot < btrfs_header_nritems(path->nodes[0]))
4168		space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4169
4170	/*
4171	 * try to push all the items after our slot into the
4172	 * right leaf
4173	 */
4174	ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
4175	if (ret < 0)
4176		return ret;
4177
4178	if (ret == 0)
4179		progress++;
4180
4181	nritems = btrfs_header_nritems(path->nodes[0]);
4182	/*
4183	 * our goal is to get our slot at the start or end of a leaf.  If
4184	 * we've done so we're done
4185	 */
4186	if (path->slots[0] == 0 || path->slots[0] == nritems)
4187		return 0;
4188
4189	if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4190		return 0;
4191
4192	/* try to push all the items before our slot into the next leaf */
4193	slot = path->slots[0];
4194	space_needed = data_size;
4195	if (slot > 0)
4196		space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4197	ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
4198	if (ret < 0)
4199		return ret;
4200
4201	if (ret == 0)
4202		progress++;
4203
4204	if (progress)
4205		return 0;
4206	return 1;
4207}
4208
4209/*
4210 * split the path's leaf in two, making sure there is at least data_size
4211 * available for the resulting leaf level of the path.
4212 *
4213 * returns 0 if all went well and < 0 on failure.
4214 */
4215static noinline int split_leaf(struct btrfs_trans_handle *trans,
4216			       struct btrfs_root *root,
4217			       const struct btrfs_key *ins_key,
4218			       struct btrfs_path *path, int data_size,
4219			       int extend)
4220{
4221	struct btrfs_disk_key disk_key;
4222	struct extent_buffer *l;
4223	u32 nritems;
4224	int mid;
4225	int slot;
4226	struct extent_buffer *right;
4227	struct btrfs_fs_info *fs_info = root->fs_info;
4228	int ret = 0;
4229	int wret;
4230	int split;
4231	int num_doubles = 0;
4232	int tried_avoid_double = 0;
4233
4234	l = path->nodes[0];
4235	slot = path->slots[0];
4236	if (extend && data_size + btrfs_item_size_nr(l, slot) +
4237	    sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
4238		return -EOVERFLOW;
4239
4240	/* first try to make some room by pushing left and right */
4241	if (data_size && path->nodes[1]) {
4242		int space_needed = data_size;
4243
4244		if (slot < btrfs_header_nritems(l))
4245			space_needed -= btrfs_leaf_free_space(l);
4246
4247		wret = push_leaf_right(trans, root, path, space_needed,
4248				       space_needed, 0, 0);
4249		if (wret < 0)
4250			return wret;
4251		if (wret) {
4252			space_needed = data_size;
4253			if (slot > 0)
4254				space_needed -= btrfs_leaf_free_space(l);
4255			wret = push_leaf_left(trans, root, path, space_needed,
4256					      space_needed, 0, (u32)-1);
4257			if (wret < 0)
4258				return wret;
4259		}
4260		l = path->nodes[0];
4261
4262		/* did the pushes work? */
4263		if (btrfs_leaf_free_space(l) >= data_size)
4264			return 0;
4265	}
4266
4267	if (!path->nodes[1]) {
4268		ret = insert_new_root(trans, root, path, 1);
4269		if (ret)
4270			return ret;
4271	}
4272again:
4273	split = 1;
4274	l = path->nodes[0];
4275	slot = path->slots[0];
4276	nritems = btrfs_header_nritems(l);
4277	mid = (nritems + 1) / 2;
4278
4279	if (mid <= slot) {
4280		if (nritems == 1 ||
4281		    leaf_space_used(l, mid, nritems - mid) + data_size >
4282			BTRFS_LEAF_DATA_SIZE(fs_info)) {
4283			if (slot >= nritems) {
4284				split = 0;
4285			} else {
4286				mid = slot;
4287				if (mid != nritems &&
4288				    leaf_space_used(l, mid, nritems - mid) +
4289				    data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4290					if (data_size && !tried_avoid_double)
4291						goto push_for_double;
4292					split = 2;
4293				}
4294			}
4295		}
4296	} else {
4297		if (leaf_space_used(l, 0, mid) + data_size >
4298			BTRFS_LEAF_DATA_SIZE(fs_info)) {
4299			if (!extend && data_size && slot == 0) {
4300				split = 0;
4301			} else if ((extend || !data_size) && slot == 0) {
4302				mid = 1;
4303			} else {
4304				mid = slot;
4305				if (mid != nritems &&
4306				    leaf_space_used(l, mid, nritems - mid) +
4307				    data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4308					if (data_size && !tried_avoid_double)
4309						goto push_for_double;
4310					split = 2;
4311				}
4312			}
4313		}
4314	}
4315
4316	if (split == 0)
4317		btrfs_cpu_key_to_disk(&disk_key, ins_key);
4318	else
4319		btrfs_item_key(l, &disk_key, mid);
4320
4321	right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
4322					     l->start, 0);
4323	if (IS_ERR(right))
4324		return PTR_ERR(right);
4325
4326	root_add_used(root, fs_info->nodesize);
 
 
 
 
 
 
 
 
 
 
 
 
 
4327
4328	if (split == 0) {
4329		if (mid <= slot) {
4330			btrfs_set_header_nritems(right, 0);
4331			insert_ptr(trans, path, &disk_key,
4332				   right->start, path->slots[1] + 1, 1);
4333			btrfs_tree_unlock(path->nodes[0]);
4334			free_extent_buffer(path->nodes[0]);
4335			path->nodes[0] = right;
4336			path->slots[0] = 0;
4337			path->slots[1] += 1;
4338		} else {
4339			btrfs_set_header_nritems(right, 0);
4340			insert_ptr(trans, path, &disk_key,
4341				   right->start, path->slots[1], 1);
4342			btrfs_tree_unlock(path->nodes[0]);
4343			free_extent_buffer(path->nodes[0]);
4344			path->nodes[0] = right;
4345			path->slots[0] = 0;
4346			if (path->slots[1] == 0)
4347				fixup_low_keys(path, &disk_key, 1);
4348		}
4349		/*
4350		 * We create a new leaf 'right' for the required ins_len and
4351		 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
4352		 * the content of ins_len to 'right'.
4353		 */
4354		return ret;
4355	}
4356
4357	copy_for_split(trans, path, l, right, slot, mid, nritems);
4358
4359	if (split == 2) {
4360		BUG_ON(num_doubles != 0);
4361		num_doubles++;
4362		goto again;
4363	}
4364
4365	return 0;
4366
4367push_for_double:
4368	push_for_double_split(trans, root, path, data_size);
4369	tried_avoid_double = 1;
4370	if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4371		return 0;
4372	goto again;
4373}
4374
4375static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4376					 struct btrfs_root *root,
4377					 struct btrfs_path *path, int ins_len)
4378{
4379	struct btrfs_key key;
4380	struct extent_buffer *leaf;
4381	struct btrfs_file_extent_item *fi;
4382	u64 extent_len = 0;
4383	u32 item_size;
4384	int ret;
4385
4386	leaf = path->nodes[0];
4387	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4388
4389	BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4390	       key.type != BTRFS_EXTENT_CSUM_KEY);
4391
4392	if (btrfs_leaf_free_space(leaf) >= ins_len)
4393		return 0;
4394
4395	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4396	if (key.type == BTRFS_EXTENT_DATA_KEY) {
4397		fi = btrfs_item_ptr(leaf, path->slots[0],
4398				    struct btrfs_file_extent_item);
4399		extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4400	}
4401	btrfs_release_path(path);
4402
4403	path->keep_locks = 1;
4404	path->search_for_split = 1;
4405	ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4406	path->search_for_split = 0;
4407	if (ret > 0)
4408		ret = -EAGAIN;
4409	if (ret < 0)
4410		goto err;
4411
4412	ret = -EAGAIN;
4413	leaf = path->nodes[0];
4414	/* if our item isn't there, return now */
4415	if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4416		goto err;
4417
4418	/* the leaf has  changed, it now has room.  return now */
4419	if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
4420		goto err;
4421
4422	if (key.type == BTRFS_EXTENT_DATA_KEY) {
4423		fi = btrfs_item_ptr(leaf, path->slots[0],
4424				    struct btrfs_file_extent_item);
4425		if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4426			goto err;
4427	}
4428
4429	btrfs_set_path_blocking(path);
4430	ret = split_leaf(trans, root, &key, path, ins_len, 1);
4431	if (ret)
4432		goto err;
4433
4434	path->keep_locks = 0;
4435	btrfs_unlock_up_safe(path, 1);
4436	return 0;
4437err:
4438	path->keep_locks = 0;
4439	return ret;
4440}
4441
4442static noinline int split_item(struct btrfs_path *path,
4443			       const struct btrfs_key *new_key,
 
 
4444			       unsigned long split_offset)
4445{
4446	struct extent_buffer *leaf;
4447	struct btrfs_item *item;
4448	struct btrfs_item *new_item;
4449	int slot;
4450	char *buf;
4451	u32 nritems;
4452	u32 item_size;
4453	u32 orig_offset;
4454	struct btrfs_disk_key disk_key;
4455
4456	leaf = path->nodes[0];
4457	BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
4458
4459	btrfs_set_path_blocking(path);
4460
4461	item = btrfs_item_nr(path->slots[0]);
4462	orig_offset = btrfs_item_offset(leaf, item);
4463	item_size = btrfs_item_size(leaf, item);
4464
4465	buf = kmalloc(item_size, GFP_NOFS);
4466	if (!buf)
4467		return -ENOMEM;
4468
4469	read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4470			    path->slots[0]), item_size);
4471
4472	slot = path->slots[0] + 1;
4473	nritems = btrfs_header_nritems(leaf);
4474	if (slot != nritems) {
4475		/* shift the items */
4476		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4477				btrfs_item_nr_offset(slot),
4478				(nritems - slot) * sizeof(struct btrfs_item));
4479	}
4480
4481	btrfs_cpu_key_to_disk(&disk_key, new_key);
4482	btrfs_set_item_key(leaf, &disk_key, slot);
4483
4484	new_item = btrfs_item_nr(slot);
4485
4486	btrfs_set_item_offset(leaf, new_item, orig_offset);
4487	btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4488
4489	btrfs_set_item_offset(leaf, item,
4490			      orig_offset + item_size - split_offset);
4491	btrfs_set_item_size(leaf, item, split_offset);
4492
4493	btrfs_set_header_nritems(leaf, nritems + 1);
4494
4495	/* write the data for the start of the original item */
4496	write_extent_buffer(leaf, buf,
4497			    btrfs_item_ptr_offset(leaf, path->slots[0]),
4498			    split_offset);
4499
4500	/* write the data for the new item */
4501	write_extent_buffer(leaf, buf + split_offset,
4502			    btrfs_item_ptr_offset(leaf, slot),
4503			    item_size - split_offset);
4504	btrfs_mark_buffer_dirty(leaf);
4505
4506	BUG_ON(btrfs_leaf_free_space(leaf) < 0);
4507	kfree(buf);
4508	return 0;
4509}
4510
4511/*
4512 * This function splits a single item into two items,
4513 * giving 'new_key' to the new item and splitting the
4514 * old one at split_offset (from the start of the item).
4515 *
4516 * The path may be released by this operation.  After
4517 * the split, the path is pointing to the old item.  The
4518 * new item is going to be in the same node as the old one.
4519 *
4520 * Note, the item being split must be smaller enough to live alone on
4521 * a tree block with room for one extra struct btrfs_item
4522 *
4523 * This allows us to split the item in place, keeping a lock on the
4524 * leaf the entire time.
4525 */
4526int btrfs_split_item(struct btrfs_trans_handle *trans,
4527		     struct btrfs_root *root,
4528		     struct btrfs_path *path,
4529		     const struct btrfs_key *new_key,
4530		     unsigned long split_offset)
4531{
4532	int ret;
4533	ret = setup_leaf_for_split(trans, root, path,
4534				   sizeof(struct btrfs_item));
4535	if (ret)
4536		return ret;
4537
4538	ret = split_item(path, new_key, split_offset);
4539	return ret;
4540}
4541
4542/*
4543 * This function duplicate a item, giving 'new_key' to the new item.
4544 * It guarantees both items live in the same tree leaf and the new item
4545 * is contiguous with the original item.
4546 *
4547 * This allows us to split file extent in place, keeping a lock on the
4548 * leaf the entire time.
4549 */
4550int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4551			 struct btrfs_root *root,
4552			 struct btrfs_path *path,
4553			 const struct btrfs_key *new_key)
4554{
4555	struct extent_buffer *leaf;
4556	int ret;
4557	u32 item_size;
4558
4559	leaf = path->nodes[0];
4560	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4561	ret = setup_leaf_for_split(trans, root, path,
4562				   item_size + sizeof(struct btrfs_item));
4563	if (ret)
4564		return ret;
4565
4566	path->slots[0]++;
4567	setup_items_for_insert(root, path, new_key, &item_size,
4568			       item_size, item_size +
4569			       sizeof(struct btrfs_item), 1);
4570	leaf = path->nodes[0];
4571	memcpy_extent_buffer(leaf,
4572			     btrfs_item_ptr_offset(leaf, path->slots[0]),
4573			     btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4574			     item_size);
4575	return 0;
4576}
4577
4578/*
4579 * make the item pointed to by the path smaller.  new_size indicates
4580 * how small to make it, and from_end tells us if we just chop bytes
4581 * off the end of the item or if we shift the item to chop bytes off
4582 * the front.
4583 */
4584void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
 
4585{
4586	int slot;
4587	struct extent_buffer *leaf;
4588	struct btrfs_item *item;
4589	u32 nritems;
4590	unsigned int data_end;
4591	unsigned int old_data_start;
4592	unsigned int old_size;
4593	unsigned int size_diff;
4594	int i;
4595	struct btrfs_map_token token;
4596
 
 
4597	leaf = path->nodes[0];
4598	slot = path->slots[0];
4599
4600	old_size = btrfs_item_size_nr(leaf, slot);
4601	if (old_size == new_size)
4602		return;
4603
4604	nritems = btrfs_header_nritems(leaf);
4605	data_end = leaf_data_end(leaf);
4606
4607	old_data_start = btrfs_item_offset_nr(leaf, slot);
4608
4609	size_diff = old_size - new_size;
4610
4611	BUG_ON(slot < 0);
4612	BUG_ON(slot >= nritems);
4613
4614	/*
4615	 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4616	 */
4617	/* first correct the data pointers */
4618	btrfs_init_map_token(&token, leaf);
4619	for (i = slot; i < nritems; i++) {
4620		u32 ioff;
4621		item = btrfs_item_nr(i);
4622
4623		ioff = btrfs_token_item_offset(leaf, item, &token);
4624		btrfs_set_token_item_offset(leaf, item,
4625					    ioff + size_diff, &token);
4626	}
4627
4628	/* shift the data */
4629	if (from_end) {
4630		memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4631			      data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4632			      data_end, old_data_start + new_size - data_end);
4633	} else {
4634		struct btrfs_disk_key disk_key;
4635		u64 offset;
4636
4637		btrfs_item_key(leaf, &disk_key, slot);
4638
4639		if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4640			unsigned long ptr;
4641			struct btrfs_file_extent_item *fi;
4642
4643			fi = btrfs_item_ptr(leaf, slot,
4644					    struct btrfs_file_extent_item);
4645			fi = (struct btrfs_file_extent_item *)(
4646			     (unsigned long)fi - size_diff);
4647
4648			if (btrfs_file_extent_type(leaf, fi) ==
4649			    BTRFS_FILE_EXTENT_INLINE) {
4650				ptr = btrfs_item_ptr_offset(leaf, slot);
4651				memmove_extent_buffer(leaf, ptr,
4652				      (unsigned long)fi,
4653				      BTRFS_FILE_EXTENT_INLINE_DATA_START);
4654			}
4655		}
4656
4657		memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4658			      data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4659			      data_end, old_data_start - data_end);
4660
4661		offset = btrfs_disk_key_offset(&disk_key);
4662		btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4663		btrfs_set_item_key(leaf, &disk_key, slot);
4664		if (slot == 0)
4665			fixup_low_keys(path, &disk_key, 1);
4666	}
4667
4668	item = btrfs_item_nr(slot);
4669	btrfs_set_item_size(leaf, item, new_size);
4670	btrfs_mark_buffer_dirty(leaf);
4671
4672	if (btrfs_leaf_free_space(leaf) < 0) {
4673		btrfs_print_leaf(leaf);
4674		BUG();
4675	}
4676}
4677
4678/*
4679 * make the item pointed to by the path bigger, data_size is the added size.
4680 */
4681void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
 
4682{
4683	int slot;
4684	struct extent_buffer *leaf;
4685	struct btrfs_item *item;
4686	u32 nritems;
4687	unsigned int data_end;
4688	unsigned int old_data;
4689	unsigned int old_size;
4690	int i;
4691	struct btrfs_map_token token;
4692
 
 
4693	leaf = path->nodes[0];
4694
4695	nritems = btrfs_header_nritems(leaf);
4696	data_end = leaf_data_end(leaf);
4697
4698	if (btrfs_leaf_free_space(leaf) < data_size) {
4699		btrfs_print_leaf(leaf);
4700		BUG();
4701	}
4702	slot = path->slots[0];
4703	old_data = btrfs_item_end_nr(leaf, slot);
4704
4705	BUG_ON(slot < 0);
4706	if (slot >= nritems) {
4707		btrfs_print_leaf(leaf);
4708		btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4709			   slot, nritems);
4710		BUG();
4711	}
4712
4713	/*
4714	 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4715	 */
4716	/* first correct the data pointers */
4717	btrfs_init_map_token(&token, leaf);
4718	for (i = slot; i < nritems; i++) {
4719		u32 ioff;
4720		item = btrfs_item_nr(i);
4721
4722		ioff = btrfs_token_item_offset(leaf, item, &token);
4723		btrfs_set_token_item_offset(leaf, item,
4724					    ioff - data_size, &token);
4725	}
4726
4727	/* shift the data */
4728	memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4729		      data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
4730		      data_end, old_data - data_end);
4731
4732	data_end = old_data;
4733	old_size = btrfs_item_size_nr(leaf, slot);
4734	item = btrfs_item_nr(slot);
4735	btrfs_set_item_size(leaf, item, old_size + data_size);
4736	btrfs_mark_buffer_dirty(leaf);
4737
4738	if (btrfs_leaf_free_space(leaf) < 0) {
4739		btrfs_print_leaf(leaf);
4740		BUG();
4741	}
4742}
4743
4744/*
4745 * this is a helper for btrfs_insert_empty_items, the main goal here is
4746 * to save stack depth by doing the bulk of the work in a function
4747 * that doesn't call btrfs_search_slot
4748 */
4749void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4750			    const struct btrfs_key *cpu_key, u32 *data_size,
4751			    u32 total_data, u32 total_size, int nr)
4752{
4753	struct btrfs_fs_info *fs_info = root->fs_info;
4754	struct btrfs_item *item;
4755	int i;
4756	u32 nritems;
4757	unsigned int data_end;
4758	struct btrfs_disk_key disk_key;
4759	struct extent_buffer *leaf;
4760	int slot;
4761	struct btrfs_map_token token;
4762
4763	if (path->slots[0] == 0) {
4764		btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4765		fixup_low_keys(path, &disk_key, 1);
4766	}
4767	btrfs_unlock_up_safe(path, 1);
4768
 
 
4769	leaf = path->nodes[0];
4770	slot = path->slots[0];
4771
4772	nritems = btrfs_header_nritems(leaf);
4773	data_end = leaf_data_end(leaf);
4774
4775	if (btrfs_leaf_free_space(leaf) < total_size) {
4776		btrfs_print_leaf(leaf);
4777		btrfs_crit(fs_info, "not enough freespace need %u have %d",
4778			   total_size, btrfs_leaf_free_space(leaf));
4779		BUG();
4780	}
4781
4782	btrfs_init_map_token(&token, leaf);
4783	if (slot != nritems) {
4784		unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4785
4786		if (old_data < data_end) {
4787			btrfs_print_leaf(leaf);
4788			btrfs_crit(fs_info, "slot %d old_data %d data_end %d",
4789				   slot, old_data, data_end);
4790			BUG();
4791		}
4792		/*
4793		 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4794		 */
4795		/* first correct the data pointers */
4796		for (i = slot; i < nritems; i++) {
4797			u32 ioff;
4798
4799			item = btrfs_item_nr(i);
4800			ioff = btrfs_token_item_offset(leaf, item, &token);
4801			btrfs_set_token_item_offset(leaf, item,
4802						    ioff - total_data, &token);
4803		}
4804		/* shift the items */
4805		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4806			      btrfs_item_nr_offset(slot),
4807			      (nritems - slot) * sizeof(struct btrfs_item));
4808
4809		/* shift the data */
4810		memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4811			      data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
4812			      data_end, old_data - data_end);
4813		data_end = old_data;
4814	}
4815
4816	/* setup the item for the new data */
4817	for (i = 0; i < nr; i++) {
4818		btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4819		btrfs_set_item_key(leaf, &disk_key, slot + i);
4820		item = btrfs_item_nr(slot + i);
4821		btrfs_set_token_item_offset(leaf, item,
4822					    data_end - data_size[i], &token);
4823		data_end -= data_size[i];
4824		btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4825	}
4826
4827	btrfs_set_header_nritems(leaf, nritems + nr);
4828	btrfs_mark_buffer_dirty(leaf);
4829
4830	if (btrfs_leaf_free_space(leaf) < 0) {
4831		btrfs_print_leaf(leaf);
4832		BUG();
4833	}
4834}
4835
4836/*
4837 * Given a key and some data, insert items into the tree.
4838 * This does all the path init required, making room in the tree if needed.
4839 */
4840int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4841			    struct btrfs_root *root,
4842			    struct btrfs_path *path,
4843			    const struct btrfs_key *cpu_key, u32 *data_size,
4844			    int nr)
4845{
4846	int ret = 0;
4847	int slot;
4848	int i;
4849	u32 total_size = 0;
4850	u32 total_data = 0;
4851
4852	for (i = 0; i < nr; i++)
4853		total_data += data_size[i];
4854
4855	total_size = total_data + (nr * sizeof(struct btrfs_item));
4856	ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4857	if (ret == 0)
4858		return -EEXIST;
4859	if (ret < 0)
4860		return ret;
4861
4862	slot = path->slots[0];
4863	BUG_ON(slot < 0);
4864
4865	setup_items_for_insert(root, path, cpu_key, data_size,
4866			       total_data, total_size, nr);
4867	return 0;
4868}
4869
4870/*
4871 * Given a key and some data, insert an item into the tree.
4872 * This does all the path init required, making room in the tree if needed.
4873 */
4874int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4875		      const struct btrfs_key *cpu_key, void *data,
4876		      u32 data_size)
4877{
4878	int ret = 0;
4879	struct btrfs_path *path;
4880	struct extent_buffer *leaf;
4881	unsigned long ptr;
4882
4883	path = btrfs_alloc_path();
4884	if (!path)
4885		return -ENOMEM;
4886	ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4887	if (!ret) {
4888		leaf = path->nodes[0];
4889		ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4890		write_extent_buffer(leaf, data, ptr, data_size);
4891		btrfs_mark_buffer_dirty(leaf);
4892	}
4893	btrfs_free_path(path);
4894	return ret;
4895}
4896
4897/*
4898 * delete the pointer from a given node.
4899 *
4900 * the tree should have been previously balanced so the deletion does not
4901 * empty a node.
4902 */
4903static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4904		    int level, int slot)
4905{
4906	struct extent_buffer *parent = path->nodes[level];
4907	u32 nritems;
4908	int ret;
4909
4910	nritems = btrfs_header_nritems(parent);
4911	if (slot != nritems - 1) {
4912		if (level) {
4913			ret = tree_mod_log_insert_move(parent, slot, slot + 1,
4914					nritems - slot - 1);
4915			BUG_ON(ret < 0);
4916		}
4917		memmove_extent_buffer(parent,
4918			      btrfs_node_key_ptr_offset(slot),
4919			      btrfs_node_key_ptr_offset(slot + 1),
4920			      sizeof(struct btrfs_key_ptr) *
4921			      (nritems - slot - 1));
4922	} else if (level) {
4923		ret = tree_mod_log_insert_key(parent, slot, MOD_LOG_KEY_REMOVE,
4924				GFP_NOFS);
4925		BUG_ON(ret < 0);
4926	}
4927
4928	nritems--;
4929	btrfs_set_header_nritems(parent, nritems);
4930	if (nritems == 0 && parent == root->node) {
4931		BUG_ON(btrfs_header_level(root->node) != 1);
4932		/* just turn the root into a leaf and break */
4933		btrfs_set_header_level(root->node, 0);
4934	} else if (slot == 0) {
4935		struct btrfs_disk_key disk_key;
4936
4937		btrfs_node_key(parent, &disk_key, 0);
4938		fixup_low_keys(path, &disk_key, level + 1);
4939	}
4940	btrfs_mark_buffer_dirty(parent);
4941}
4942
4943/*
4944 * a helper function to delete the leaf pointed to by path->slots[1] and
4945 * path->nodes[1].
4946 *
4947 * This deletes the pointer in path->nodes[1] and frees the leaf
4948 * block extent.  zero is returned if it all worked out, < 0 otherwise.
4949 *
4950 * The path must have already been setup for deleting the leaf, including
4951 * all the proper balancing.  path->nodes[1] must be locked.
4952 */
4953static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4954				    struct btrfs_root *root,
4955				    struct btrfs_path *path,
4956				    struct extent_buffer *leaf)
4957{
4958	WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4959	del_ptr(root, path, 1, path->slots[1]);
4960
4961	/*
4962	 * btrfs_free_extent is expensive, we want to make sure we
4963	 * aren't holding any locks when we call it
4964	 */
4965	btrfs_unlock_up_safe(path, 0);
4966
4967	root_sub_used(root, leaf->len);
4968
4969	extent_buffer_get(leaf);
4970	btrfs_free_tree_block(trans, root, leaf, 0, 1);
4971	free_extent_buffer_stale(leaf);
4972}
4973/*
4974 * delete the item at the leaf level in path.  If that empties
4975 * the leaf, remove it from the tree
4976 */
4977int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4978		    struct btrfs_path *path, int slot, int nr)
4979{
4980	struct btrfs_fs_info *fs_info = root->fs_info;
4981	struct extent_buffer *leaf;
4982	struct btrfs_item *item;
4983	u32 last_off;
4984	u32 dsize = 0;
4985	int ret = 0;
4986	int wret;
4987	int i;
4988	u32 nritems;
 
 
 
4989
4990	leaf = path->nodes[0];
4991	last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4992
4993	for (i = 0; i < nr; i++)
4994		dsize += btrfs_item_size_nr(leaf, slot + i);
4995
4996	nritems = btrfs_header_nritems(leaf);
4997
4998	if (slot + nr != nritems) {
4999		int data_end = leaf_data_end(leaf);
5000		struct btrfs_map_token token;
5001
5002		memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
5003			      data_end + dsize,
5004			      BTRFS_LEAF_DATA_OFFSET + data_end,
5005			      last_off - data_end);
5006
5007		btrfs_init_map_token(&token, leaf);
5008		for (i = slot + nr; i < nritems; i++) {
5009			u32 ioff;
5010
5011			item = btrfs_item_nr(i);
5012			ioff = btrfs_token_item_offset(leaf, item, &token);
5013			btrfs_set_token_item_offset(leaf, item,
5014						    ioff + dsize, &token);
5015		}
5016
5017		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
5018			      btrfs_item_nr_offset(slot + nr),
5019			      sizeof(struct btrfs_item) *
5020			      (nritems - slot - nr));
5021	}
5022	btrfs_set_header_nritems(leaf, nritems - nr);
5023	nritems -= nr;
5024
5025	/* delete the leaf if we've emptied it */
5026	if (nritems == 0) {
5027		if (leaf == root->node) {
5028			btrfs_set_header_level(leaf, 0);
5029		} else {
5030			btrfs_set_path_blocking(path);
5031			btrfs_clean_tree_block(leaf);
5032			btrfs_del_leaf(trans, root, path, leaf);
5033		}
5034	} else {
5035		int used = leaf_space_used(leaf, 0, nritems);
5036		if (slot == 0) {
5037			struct btrfs_disk_key disk_key;
5038
5039			btrfs_item_key(leaf, &disk_key, 0);
5040			fixup_low_keys(path, &disk_key, 1);
5041		}
5042
5043		/* delete the leaf if it is mostly empty */
5044		if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
5045			/* push_leaf_left fixes the path.
5046			 * make sure the path still points to our leaf
5047			 * for possible call to del_ptr below
5048			 */
5049			slot = path->slots[1];
5050			extent_buffer_get(leaf);
5051
5052			btrfs_set_path_blocking(path);
5053			wret = push_leaf_left(trans, root, path, 1, 1,
5054					      1, (u32)-1);
5055			if (wret < 0 && wret != -ENOSPC)
5056				ret = wret;
5057
5058			if (path->nodes[0] == leaf &&
5059			    btrfs_header_nritems(leaf)) {
5060				wret = push_leaf_right(trans, root, path, 1,
5061						       1, 1, 0);
5062				if (wret < 0 && wret != -ENOSPC)
5063					ret = wret;
5064			}
5065
5066			if (btrfs_header_nritems(leaf) == 0) {
5067				path->slots[1] = slot;
5068				btrfs_del_leaf(trans, root, path, leaf);
5069				free_extent_buffer(leaf);
5070				ret = 0;
5071			} else {
5072				/* if we're still in the path, make sure
5073				 * we're dirty.  Otherwise, one of the
5074				 * push_leaf functions must have already
5075				 * dirtied this buffer
5076				 */
5077				if (path->nodes[0] == leaf)
5078					btrfs_mark_buffer_dirty(leaf);
5079				free_extent_buffer(leaf);
5080			}
5081		} else {
5082			btrfs_mark_buffer_dirty(leaf);
5083		}
5084	}
5085	return ret;
5086}
5087
5088/*
5089 * search the tree again to find a leaf with lesser keys
5090 * returns 0 if it found something or 1 if there are no lesser leaves.
5091 * returns < 0 on io errors.
5092 *
5093 * This may release the path, and so you may lose any locks held at the
5094 * time you call it.
5095 */
5096int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
5097{
5098	struct btrfs_key key;
5099	struct btrfs_disk_key found_key;
5100	int ret;
5101
5102	btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
5103
5104	if (key.offset > 0) {
5105		key.offset--;
5106	} else if (key.type > 0) {
5107		key.type--;
5108		key.offset = (u64)-1;
5109	} else if (key.objectid > 0) {
5110		key.objectid--;
5111		key.type = (u8)-1;
5112		key.offset = (u64)-1;
5113	} else {
5114		return 1;
5115	}
5116
5117	btrfs_release_path(path);
5118	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5119	if (ret < 0)
5120		return ret;
5121	btrfs_item_key(path->nodes[0], &found_key, 0);
5122	ret = comp_keys(&found_key, &key);
5123	/*
5124	 * We might have had an item with the previous key in the tree right
5125	 * before we released our path. And after we released our path, that
5126	 * item might have been pushed to the first slot (0) of the leaf we
5127	 * were holding due to a tree balance. Alternatively, an item with the
5128	 * previous key can exist as the only element of a leaf (big fat item).
5129	 * Therefore account for these 2 cases, so that our callers (like
5130	 * btrfs_previous_item) don't miss an existing item with a key matching
5131	 * the previous key we computed above.
5132	 */
5133	if (ret <= 0)
5134		return 0;
5135	return 1;
5136}
5137
5138/*
5139 * A helper function to walk down the tree starting at min_key, and looking
5140 * for nodes or leaves that are have a minimum transaction id.
5141 * This is used by the btree defrag code, and tree logging
5142 *
5143 * This does not cow, but it does stuff the starting key it finds back
5144 * into min_key, so you can call btrfs_search_slot with cow=1 on the
5145 * key and get a writable path.
5146 *
 
 
 
5147 * This honors path->lowest_level to prevent descent past a given level
5148 * of the tree.
5149 *
5150 * min_trans indicates the oldest transaction that you are interested
5151 * in walking through.  Any nodes or leaves older than min_trans are
5152 * skipped over (without reading them).
5153 *
5154 * returns zero if something useful was found, < 0 on error and 1 if there
5155 * was nothing in the tree that matched the search criteria.
5156 */
5157int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
5158			 struct btrfs_path *path,
5159			 u64 min_trans)
5160{
5161	struct extent_buffer *cur;
5162	struct btrfs_key found_key;
5163	int slot;
5164	int sret;
5165	u32 nritems;
5166	int level;
5167	int ret = 1;
5168	int keep_locks = path->keep_locks;
5169
5170	path->keep_locks = 1;
5171again:
5172	cur = btrfs_read_lock_root_node(root);
5173	level = btrfs_header_level(cur);
5174	WARN_ON(path->nodes[level]);
5175	path->nodes[level] = cur;
5176	path->locks[level] = BTRFS_READ_LOCK;
5177
5178	if (btrfs_header_generation(cur) < min_trans) {
5179		ret = 1;
5180		goto out;
5181	}
5182	while (1) {
5183		nritems = btrfs_header_nritems(cur);
5184		level = btrfs_header_level(cur);
5185		sret = btrfs_bin_search(cur, min_key, level, &slot);
5186		if (sret < 0) {
5187			ret = sret;
5188			goto out;
5189		}
5190
5191		/* at the lowest level, we're done, setup the path and exit */
5192		if (level == path->lowest_level) {
5193			if (slot >= nritems)
5194				goto find_next_key;
5195			ret = 0;
5196			path->slots[level] = slot;
5197			btrfs_item_key_to_cpu(cur, &found_key, slot);
5198			goto out;
5199		}
5200		if (sret && slot > 0)
5201			slot--;
5202		/*
5203		 * check this node pointer against the min_trans parameters.
5204		 * If it is too old, old, skip to the next one.
5205		 */
5206		while (slot < nritems) {
5207			u64 gen;
5208
5209			gen = btrfs_node_ptr_generation(cur, slot);
5210			if (gen < min_trans) {
5211				slot++;
5212				continue;
5213			}
5214			break;
5215		}
5216find_next_key:
5217		/*
5218		 * we didn't find a candidate key in this node, walk forward
5219		 * and find another one
5220		 */
5221		if (slot >= nritems) {
5222			path->slots[level] = slot;
5223			btrfs_set_path_blocking(path);
5224			sret = btrfs_find_next_key(root, path, min_key, level,
5225						  min_trans);
5226			if (sret == 0) {
5227				btrfs_release_path(path);
5228				goto again;
5229			} else {
5230				goto out;
5231			}
5232		}
5233		/* save our key for returning back */
5234		btrfs_node_key_to_cpu(cur, &found_key, slot);
5235		path->slots[level] = slot;
5236		if (level == path->lowest_level) {
5237			ret = 0;
5238			goto out;
5239		}
5240		btrfs_set_path_blocking(path);
5241		cur = btrfs_read_node_slot(cur, slot);
5242		if (IS_ERR(cur)) {
5243			ret = PTR_ERR(cur);
5244			goto out;
5245		}
5246
5247		btrfs_tree_read_lock(cur);
5248
5249		path->locks[level - 1] = BTRFS_READ_LOCK;
5250		path->nodes[level - 1] = cur;
5251		unlock_up(path, level, 1, 0, NULL);
 
5252	}
5253out:
5254	path->keep_locks = keep_locks;
5255	if (ret == 0) {
5256		btrfs_unlock_up_safe(path, path->lowest_level + 1);
5257		btrfs_set_path_blocking(path);
5258		memcpy(min_key, &found_key, sizeof(found_key));
5259	}
5260	return ret;
5261}
5262
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5263/*
5264 * this is similar to btrfs_next_leaf, but does not try to preserve
5265 * and fixup the path.  It looks for and returns the next key in the
5266 * tree based on the current path and the min_trans parameters.
5267 *
5268 * 0 is returned if another key is found, < 0 if there are any errors
5269 * and 1 is returned if there are no higher keys in the tree
5270 *
5271 * path->keep_locks should be set to 1 on the search made before
5272 * calling this function.
5273 */
5274int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5275			struct btrfs_key *key, int level, u64 min_trans)
5276{
5277	int slot;
5278	struct extent_buffer *c;
5279
5280	WARN_ON(!path->keep_locks && !path->skip_locking);
5281	while (level < BTRFS_MAX_LEVEL) {
5282		if (!path->nodes[level])
5283			return 1;
5284
5285		slot = path->slots[level] + 1;
5286		c = path->nodes[level];
5287next:
5288		if (slot >= btrfs_header_nritems(c)) {
5289			int ret;
5290			int orig_lowest;
5291			struct btrfs_key cur_key;
5292			if (level + 1 >= BTRFS_MAX_LEVEL ||
5293			    !path->nodes[level + 1])
5294				return 1;
5295
5296			if (path->locks[level + 1] || path->skip_locking) {
5297				level++;
5298				continue;
5299			}
5300
5301			slot = btrfs_header_nritems(c) - 1;
5302			if (level == 0)
5303				btrfs_item_key_to_cpu(c, &cur_key, slot);
5304			else
5305				btrfs_node_key_to_cpu(c, &cur_key, slot);
5306
5307			orig_lowest = path->lowest_level;
5308			btrfs_release_path(path);
5309			path->lowest_level = level;
5310			ret = btrfs_search_slot(NULL, root, &cur_key, path,
5311						0, 0);
5312			path->lowest_level = orig_lowest;
5313			if (ret < 0)
5314				return ret;
5315
5316			c = path->nodes[level];
5317			slot = path->slots[level];
5318			if (ret == 0)
5319				slot++;
5320			goto next;
5321		}
5322
5323		if (level == 0)
5324			btrfs_item_key_to_cpu(c, key, slot);
5325		else {
5326			u64 gen = btrfs_node_ptr_generation(c, slot);
5327
5328			if (gen < min_trans) {
5329				slot++;
5330				goto next;
5331			}
5332			btrfs_node_key_to_cpu(c, key, slot);
5333		}
5334		return 0;
5335	}
5336	return 1;
5337}
5338
5339/*
5340 * search the tree again to find a leaf with greater keys
5341 * returns 0 if it found something or 1 if there are no greater leaves.
5342 * returns < 0 on io errors.
5343 */
5344int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5345{
5346	return btrfs_next_old_leaf(root, path, 0);
5347}
5348
5349int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5350			u64 time_seq)
5351{
5352	int slot;
5353	int level;
5354	struct extent_buffer *c;
5355	struct extent_buffer *next;
5356	struct btrfs_key key;
5357	u32 nritems;
5358	int ret;
5359	int old_spinning = path->leave_spinning;
5360	int next_rw_lock = 0;
5361
5362	nritems = btrfs_header_nritems(path->nodes[0]);
5363	if (nritems == 0)
5364		return 1;
5365
5366	btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5367again:
5368	level = 1;
5369	next = NULL;
5370	next_rw_lock = 0;
5371	btrfs_release_path(path);
5372
5373	path->keep_locks = 1;
5374	path->leave_spinning = 1;
5375
5376	if (time_seq)
5377		ret = btrfs_search_old_slot(root, &key, path, time_seq);
5378	else
5379		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5380	path->keep_locks = 0;
5381
5382	if (ret < 0)
5383		return ret;
5384
5385	nritems = btrfs_header_nritems(path->nodes[0]);
5386	/*
5387	 * by releasing the path above we dropped all our locks.  A balance
5388	 * could have added more items next to the key that used to be
5389	 * at the very end of the block.  So, check again here and
5390	 * advance the path if there are now more items available.
5391	 */
5392	if (nritems > 0 && path->slots[0] < nritems - 1) {
5393		if (ret == 0)
5394			path->slots[0]++;
5395		ret = 0;
5396		goto done;
5397	}
5398	/*
5399	 * So the above check misses one case:
5400	 * - after releasing the path above, someone has removed the item that
5401	 *   used to be at the very end of the block, and balance between leafs
5402	 *   gets another one with bigger key.offset to replace it.
5403	 *
5404	 * This one should be returned as well, or we can get leaf corruption
5405	 * later(esp. in __btrfs_drop_extents()).
5406	 *
5407	 * And a bit more explanation about this check,
5408	 * with ret > 0, the key isn't found, the path points to the slot
5409	 * where it should be inserted, so the path->slots[0] item must be the
5410	 * bigger one.
5411	 */
5412	if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
5413		ret = 0;
5414		goto done;
5415	}
5416
5417	while (level < BTRFS_MAX_LEVEL) {
5418		if (!path->nodes[level]) {
5419			ret = 1;
5420			goto done;
5421		}
5422
5423		slot = path->slots[level] + 1;
5424		c = path->nodes[level];
5425		if (slot >= btrfs_header_nritems(c)) {
5426			level++;
5427			if (level == BTRFS_MAX_LEVEL) {
5428				ret = 1;
5429				goto done;
5430			}
5431			continue;
5432		}
5433
5434		if (next) {
5435			btrfs_tree_unlock_rw(next, next_rw_lock);
5436			free_extent_buffer(next);
5437		}
5438
5439		next = c;
5440		next_rw_lock = path->locks[level];
5441		ret = read_block_for_search(root, path, &next, level,
5442					    slot, &key);
5443		if (ret == -EAGAIN)
5444			goto again;
5445
5446		if (ret < 0) {
5447			btrfs_release_path(path);
5448			goto done;
5449		}
5450
5451		if (!path->skip_locking) {
5452			ret = btrfs_try_tree_read_lock(next);
5453			if (!ret && time_seq) {
5454				/*
5455				 * If we don't get the lock, we may be racing
5456				 * with push_leaf_left, holding that lock while
5457				 * itself waiting for the leaf we've currently
5458				 * locked. To solve this situation, we give up
5459				 * on our lock and cycle.
5460				 */
5461				free_extent_buffer(next);
5462				btrfs_release_path(path);
5463				cond_resched();
5464				goto again;
5465			}
5466			if (!ret) {
5467				btrfs_set_path_blocking(path);
5468				btrfs_tree_read_lock(next);
 
 
5469			}
5470			next_rw_lock = BTRFS_READ_LOCK;
5471		}
5472		break;
5473	}
5474	path->slots[level] = slot;
5475	while (1) {
5476		level--;
5477		c = path->nodes[level];
5478		if (path->locks[level])
5479			btrfs_tree_unlock_rw(c, path->locks[level]);
5480
5481		free_extent_buffer(c);
5482		path->nodes[level] = next;
5483		path->slots[level] = 0;
5484		if (!path->skip_locking)
5485			path->locks[level] = next_rw_lock;
5486		if (!level)
5487			break;
5488
5489		ret = read_block_for_search(root, path, &next, level,
5490					    0, &key);
5491		if (ret == -EAGAIN)
5492			goto again;
5493
5494		if (ret < 0) {
5495			btrfs_release_path(path);
5496			goto done;
5497		}
5498
5499		if (!path->skip_locking) {
5500			ret = btrfs_try_tree_read_lock(next);
5501			if (!ret) {
5502				btrfs_set_path_blocking(path);
5503				btrfs_tree_read_lock(next);
 
 
5504			}
5505			next_rw_lock = BTRFS_READ_LOCK;
5506		}
5507	}
5508	ret = 0;
5509done:
5510	unlock_up(path, 0, 1, 0, NULL);
5511	path->leave_spinning = old_spinning;
5512	if (!old_spinning)
5513		btrfs_set_path_blocking(path);
5514
5515	return ret;
5516}
5517
5518/*
5519 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5520 * searching until it gets past min_objectid or finds an item of 'type'
5521 *
5522 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5523 */
5524int btrfs_previous_item(struct btrfs_root *root,
5525			struct btrfs_path *path, u64 min_objectid,
5526			int type)
5527{
5528	struct btrfs_key found_key;
5529	struct extent_buffer *leaf;
5530	u32 nritems;
5531	int ret;
5532
5533	while (1) {
5534		if (path->slots[0] == 0) {
5535			btrfs_set_path_blocking(path);
5536			ret = btrfs_prev_leaf(root, path);
5537			if (ret != 0)
5538				return ret;
5539		} else {
5540			path->slots[0]--;
5541		}
5542		leaf = path->nodes[0];
5543		nritems = btrfs_header_nritems(leaf);
5544		if (nritems == 0)
5545			return 1;
5546		if (path->slots[0] == nritems)
5547			path->slots[0]--;
5548
5549		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5550		if (found_key.objectid < min_objectid)
5551			break;
5552		if (found_key.type == type)
5553			return 0;
5554		if (found_key.objectid == min_objectid &&
5555		    found_key.type < type)
5556			break;
5557	}
5558	return 1;
5559}
5560
5561/*
5562 * search in extent tree to find a previous Metadata/Data extent item with
5563 * min objecitd.
5564 *
5565 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5566 */
5567int btrfs_previous_extent_item(struct btrfs_root *root,
5568			struct btrfs_path *path, u64 min_objectid)
5569{
5570	struct btrfs_key found_key;
5571	struct extent_buffer *leaf;
5572	u32 nritems;
5573	int ret;
5574
5575	while (1) {
5576		if (path->slots[0] == 0) {
5577			btrfs_set_path_blocking(path);
5578			ret = btrfs_prev_leaf(root, path);
5579			if (ret != 0)
5580				return ret;
5581		} else {
5582			path->slots[0]--;
5583		}
5584		leaf = path->nodes[0];
5585		nritems = btrfs_header_nritems(leaf);
5586		if (nritems == 0)
5587			return 1;
5588		if (path->slots[0] == nritems)
5589			path->slots[0]--;
5590
5591		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5592		if (found_key.objectid < min_objectid)
5593			break;
5594		if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5595		    found_key.type == BTRFS_METADATA_ITEM_KEY)
5596			return 0;
5597		if (found_key.objectid == min_objectid &&
5598		    found_key.type < BTRFS_EXTENT_ITEM_KEY)
5599			break;
5600	}
5601	return 1;
5602}