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[10];
  35	const char	driver[12];
  36} btrfs_csums[] = {
  37	[BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
  38	[BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
  39	[BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
  40	[BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
  41				     .driver = "blake2b-256" },
  42};
  43
  44int btrfs_super_csum_size(const struct btrfs_super_block *s)
  45{
  46	u16 t = btrfs_super_csum_type(s);
  47	/*
  48	 * csum type is validated at mount time
  49	 */
  50	return btrfs_csums[t].size;
  51}
  52
  53const char *btrfs_super_csum_name(u16 csum_type)
 
 
 
 
  54{
  55	/* csum type is validated at mount time */
  56	return btrfs_csums[csum_type].name;
 
 
 
 
 
 
 
 
  57}
  58
  59/*
  60 * Return driver name if defined, otherwise the name that's also a valid driver
  61 * name
 
 
 
 
  62 */
  63const char *btrfs_super_csum_driver(u16 csum_type)
 
  64{
  65	/* csum type is validated at mount time */
  66	return btrfs_csums[csum_type].driver[0] ?
  67		btrfs_csums[csum_type].driver :
  68		btrfs_csums[csum_type].name;
  69}
  70
  71size_t __attribute_const__ btrfs_get_num_csums(void)
  72{
  73	return ARRAY_SIZE(btrfs_csums);
  74}
 
 
 
 
  75
  76struct btrfs_path *btrfs_alloc_path(void)
  77{
  78	return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
 
 
 
 
 
 
 
 
 
  79}
  80
  81/* this also releases the path */
  82void btrfs_free_path(struct btrfs_path *p)
  83{
  84	if (!p)
  85		return;
  86	btrfs_release_path(p);
  87	kmem_cache_free(btrfs_path_cachep, p);
  88}
  89
  90/*
  91 * path release drops references on the extent buffers in the path
  92 * and it drops any locks held by this path
  93 *
  94 * It is safe to call this on paths that no locks or extent buffers held.
  95 */
  96noinline void btrfs_release_path(struct btrfs_path *p)
  97{
  98	int i;
  99
 100	for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
 101		p->slots[i] = 0;
 102		if (!p->nodes[i])
 103			continue;
 104		if (p->locks[i]) {
 105			btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
 106			p->locks[i] = 0;
 107		}
 108		free_extent_buffer(p->nodes[i]);
 109		p->nodes[i] = NULL;
 110	}
 111}
 112
 113/*
 114 * safely gets a reference on the root node of a tree.  A lock
 115 * is not taken, so a concurrent writer may put a different node
 116 * at the root of the tree.  See btrfs_lock_root_node for the
 117 * looping required.
 118 *
 119 * The extent buffer returned by this has a reference taken, so
 120 * it won't disappear.  It may stop being the root of the tree
 121 * at any time because there are no locks held.
 122 */
 123struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
 124{
 125	struct extent_buffer *eb;
 126
 127	while (1) {
 128		rcu_read_lock();
 129		eb = rcu_dereference(root->node);
 130
 131		/*
 132		 * RCU really hurts here, we could free up the root node because
 133		 * it was COWed but we may not get the new root node yet so do
 134		 * the inc_not_zero dance and if it doesn't work then
 135		 * synchronize_rcu and try again.
 136		 */
 137		if (atomic_inc_not_zero(&eb->refs)) {
 138			rcu_read_unlock();
 139			break;
 140		}
 141		rcu_read_unlock();
 142		synchronize_rcu();
 143	}
 144	return eb;
 145}
 146
 147/*
 148 * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
 149 * just get put onto a simple dirty list.  Transaction walks this list to make
 150 * sure they get properly updated on disk.
 151 */
 152static void add_root_to_dirty_list(struct btrfs_root *root)
 153{
 154	struct btrfs_fs_info *fs_info = root->fs_info;
 155
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 156	if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
 157	    !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
 158		return;
 159
 160	spin_lock(&fs_info->trans_lock);
 161	if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
 162		/* Want the extent tree to be the last on the list */
 163		if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
 164			list_move_tail(&root->dirty_list,
 165				       &fs_info->dirty_cowonly_roots);
 166		else
 167			list_move(&root->dirty_list,
 168				  &fs_info->dirty_cowonly_roots);
 169	}
 170	spin_unlock(&fs_info->trans_lock);
 171}
 172
 173/*
 174 * used by snapshot creation to make a copy of a root for a tree with
 175 * a given objectid.  The buffer with the new root node is returned in
 176 * cow_ret, and this func returns zero on success or a negative error code.
 177 */
 178int btrfs_copy_root(struct btrfs_trans_handle *trans,
 179		      struct btrfs_root *root,
 180		      struct extent_buffer *buf,
 181		      struct extent_buffer **cow_ret, u64 new_root_objectid)
 182{
 183	struct btrfs_fs_info *fs_info = root->fs_info;
 184	struct extent_buffer *cow;
 185	int ret = 0;
 186	int level;
 187	struct btrfs_disk_key disk_key;
 188
 189	WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 190		trans->transid != fs_info->running_transaction->transid);
 191	WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 192		trans->transid != root->last_trans);
 193
 194	level = btrfs_header_level(buf);
 195	if (level == 0)
 196		btrfs_item_key(buf, &disk_key, 0);
 197	else
 198		btrfs_node_key(buf, &disk_key, 0);
 199
 200	cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
 201			&disk_key, level, buf->start, 0);
 202	if (IS_ERR(cow))
 203		return PTR_ERR(cow);
 204
 205	copy_extent_buffer_full(cow, buf);
 206	btrfs_set_header_bytenr(cow, cow->start);
 207	btrfs_set_header_generation(cow, trans->transid);
 208	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 209	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 210				     BTRFS_HEADER_FLAG_RELOC);
 211	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 212		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 213	else
 214		btrfs_set_header_owner(cow, new_root_objectid);
 215
 216	write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
 
 217
 218	WARN_ON(btrfs_header_generation(buf) > trans->transid);
 219	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 220		ret = btrfs_inc_ref(trans, root, cow, 1);
 221	else
 222		ret = btrfs_inc_ref(trans, root, cow, 0);
 223
 224	if (ret)
 225		return ret;
 226
 227	btrfs_mark_buffer_dirty(cow);
 228	*cow_ret = cow;
 229	return 0;
 230}
 231
 232enum mod_log_op {
 233	MOD_LOG_KEY_REPLACE,
 234	MOD_LOG_KEY_ADD,
 235	MOD_LOG_KEY_REMOVE,
 236	MOD_LOG_KEY_REMOVE_WHILE_FREEING,
 237	MOD_LOG_KEY_REMOVE_WHILE_MOVING,
 238	MOD_LOG_MOVE_KEYS,
 239	MOD_LOG_ROOT_REPLACE,
 240};
 241
 
 
 
 
 
 242struct tree_mod_root {
 243	u64 logical;
 244	u8 level;
 245};
 246
 247struct tree_mod_elem {
 248	struct rb_node node;
 249	u64 logical;
 250	u64 seq;
 251	enum mod_log_op op;
 252
 253	/* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
 254	int slot;
 255
 256	/* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
 257	u64 generation;
 258
 259	/* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
 260	struct btrfs_disk_key key;
 261	u64 blockptr;
 262
 263	/* this is used for op == MOD_LOG_MOVE_KEYS */
 264	struct {
 265		int dst_slot;
 266		int nr_items;
 267	} move;
 268
 269	/* this is used for op == MOD_LOG_ROOT_REPLACE */
 270	struct tree_mod_root old_root;
 271};
 272
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 273/*
 274 * Pull a new tree mod seq number for our operation.
 275 */
 276static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
 277{
 278	return atomic64_inc_return(&fs_info->tree_mod_seq);
 279}
 280
 281/*
 282 * This adds a new blocker to the tree mod log's blocker list if the @elem
 283 * passed does not already have a sequence number set. So when a caller expects
 284 * to record tree modifications, it should ensure to set elem->seq to zero
 285 * before calling btrfs_get_tree_mod_seq.
 286 * Returns a fresh, unused tree log modification sequence number, even if no new
 287 * blocker was added.
 288 */
 289u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
 290			   struct seq_list *elem)
 291{
 292	write_lock(&fs_info->tree_mod_log_lock);
 
 293	if (!elem->seq) {
 294		elem->seq = btrfs_inc_tree_mod_seq(fs_info);
 295		list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
 296	}
 297	write_unlock(&fs_info->tree_mod_log_lock);
 
 298
 299	return elem->seq;
 300}
 301
 302void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
 303			    struct seq_list *elem)
 304{
 305	struct rb_root *tm_root;
 306	struct rb_node *node;
 307	struct rb_node *next;
 
 308	struct tree_mod_elem *tm;
 309	u64 min_seq = (u64)-1;
 310	u64 seq_putting = elem->seq;
 311
 312	if (!seq_putting)
 313		return;
 314
 315	write_lock(&fs_info->tree_mod_log_lock);
 316	list_del(&elem->list);
 317	elem->seq = 0;
 318
 319	if (!list_empty(&fs_info->tree_mod_seq_list)) {
 320		struct seq_list *first;
 321
 322		first = list_first_entry(&fs_info->tree_mod_seq_list,
 323					 struct seq_list, list);
 324		if (seq_putting > first->seq) {
 325			/*
 326			 * Blocker with lower sequence number exists, we
 327			 * cannot remove anything from the log.
 328			 */
 329			write_unlock(&fs_info->tree_mod_log_lock);
 330			return;
 331		}
 332		min_seq = first->seq;
 333	}
 
 334
 335	/*
 336	 * anything that's lower than the lowest existing (read: blocked)
 337	 * sequence number can be removed from the tree.
 338	 */
 
 339	tm_root = &fs_info->tree_mod_log;
 340	for (node = rb_first(tm_root); node; node = next) {
 341		next = rb_next(node);
 342		tm = rb_entry(node, struct tree_mod_elem, node);
 343		if (tm->seq >= min_seq)
 344			continue;
 345		rb_erase(node, tm_root);
 346		kfree(tm);
 347	}
 348	write_unlock(&fs_info->tree_mod_log_lock);
 349}
 350
 351/*
 352 * key order of the log:
 353 *       node/leaf start address -> sequence
 354 *
 355 * The 'start address' is the logical address of the *new* root node
 356 * for root replace operations, or the logical address of the affected
 357 * block for all other operations.
 
 
 358 */
 359static noinline int
 360__tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
 361{
 362	struct rb_root *tm_root;
 363	struct rb_node **new;
 364	struct rb_node *parent = NULL;
 365	struct tree_mod_elem *cur;
 366
 367	lockdep_assert_held_write(&fs_info->tree_mod_log_lock);
 368
 369	tm->seq = btrfs_inc_tree_mod_seq(fs_info);
 370
 371	tm_root = &fs_info->tree_mod_log;
 372	new = &tm_root->rb_node;
 373	while (*new) {
 374		cur = rb_entry(*new, struct tree_mod_elem, node);
 375		parent = *new;
 376		if (cur->logical < tm->logical)
 377			new = &((*new)->rb_left);
 378		else if (cur->logical > tm->logical)
 379			new = &((*new)->rb_right);
 380		else if (cur->seq < tm->seq)
 381			new = &((*new)->rb_left);
 382		else if (cur->seq > tm->seq)
 383			new = &((*new)->rb_right);
 384		else
 385			return -EEXIST;
 386	}
 387
 388	rb_link_node(&tm->node, parent, new);
 389	rb_insert_color(&tm->node, tm_root);
 390	return 0;
 391}
 392
 393/*
 394 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
 395 * returns zero with the tree_mod_log_lock acquired. The caller must hold
 396 * this until all tree mod log insertions are recorded in the rb tree and then
 397 * write unlock fs_info::tree_mod_log_lock.
 398 */
 399static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
 400				    struct extent_buffer *eb) {
 401	smp_mb();
 402	if (list_empty(&(fs_info)->tree_mod_seq_list))
 403		return 1;
 404	if (eb && btrfs_header_level(eb) == 0)
 405		return 1;
 406
 407	write_lock(&fs_info->tree_mod_log_lock);
 408	if (list_empty(&(fs_info)->tree_mod_seq_list)) {
 409		write_unlock(&fs_info->tree_mod_log_lock);
 410		return 1;
 411	}
 412
 413	return 0;
 414}
 415
 416/* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
 417static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
 418				    struct extent_buffer *eb)
 419{
 420	smp_mb();
 421	if (list_empty(&(fs_info)->tree_mod_seq_list))
 422		return 0;
 423	if (eb && btrfs_header_level(eb) == 0)
 424		return 0;
 425
 426	return 1;
 427}
 428
 429static struct tree_mod_elem *
 430alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
 431		    enum mod_log_op op, gfp_t flags)
 432{
 433	struct tree_mod_elem *tm;
 434
 435	tm = kzalloc(sizeof(*tm), flags);
 436	if (!tm)
 437		return NULL;
 438
 439	tm->logical = eb->start;
 440	if (op != MOD_LOG_KEY_ADD) {
 441		btrfs_node_key(eb, &tm->key, slot);
 442		tm->blockptr = btrfs_node_blockptr(eb, slot);
 443	}
 444	tm->op = op;
 445	tm->slot = slot;
 446	tm->generation = btrfs_node_ptr_generation(eb, slot);
 447	RB_CLEAR_NODE(&tm->node);
 448
 449	return tm;
 450}
 451
 452static noinline int tree_mod_log_insert_key(struct extent_buffer *eb, int slot,
 453		enum mod_log_op op, gfp_t flags)
 
 
 454{
 455	struct tree_mod_elem *tm;
 456	int ret;
 457
 458	if (!tree_mod_need_log(eb->fs_info, eb))
 459		return 0;
 460
 461	tm = alloc_tree_mod_elem(eb, slot, op, flags);
 462	if (!tm)
 463		return -ENOMEM;
 464
 465	if (tree_mod_dont_log(eb->fs_info, eb)) {
 466		kfree(tm);
 467		return 0;
 468	}
 469
 470	ret = __tree_mod_log_insert(eb->fs_info, tm);
 471	write_unlock(&eb->fs_info->tree_mod_log_lock);
 472	if (ret)
 473		kfree(tm);
 474
 475	return ret;
 476}
 477
 478static noinline int tree_mod_log_insert_move(struct extent_buffer *eb,
 479		int dst_slot, int src_slot, int nr_items)
 
 
 480{
 481	struct tree_mod_elem *tm = NULL;
 482	struct tree_mod_elem **tm_list = NULL;
 483	int ret = 0;
 484	int i;
 485	int locked = 0;
 486
 487	if (!tree_mod_need_log(eb->fs_info, eb))
 488		return 0;
 489
 490	tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS);
 491	if (!tm_list)
 492		return -ENOMEM;
 493
 494	tm = kzalloc(sizeof(*tm), GFP_NOFS);
 495	if (!tm) {
 496		ret = -ENOMEM;
 497		goto free_tms;
 498	}
 499
 500	tm->logical = eb->start;
 501	tm->slot = src_slot;
 502	tm->move.dst_slot = dst_slot;
 503	tm->move.nr_items = nr_items;
 504	tm->op = MOD_LOG_MOVE_KEYS;
 505
 506	for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
 507		tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
 508		    MOD_LOG_KEY_REMOVE_WHILE_MOVING, GFP_NOFS);
 509		if (!tm_list[i]) {
 510			ret = -ENOMEM;
 511			goto free_tms;
 512		}
 513	}
 514
 515	if (tree_mod_dont_log(eb->fs_info, eb))
 516		goto free_tms;
 517	locked = 1;
 518
 519	/*
 520	 * When we override something during the move, we log these removals.
 521	 * This can only happen when we move towards the beginning of the
 522	 * buffer, i.e. dst_slot < src_slot.
 523	 */
 524	for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
 525		ret = __tree_mod_log_insert(eb->fs_info, tm_list[i]);
 526		if (ret)
 527			goto free_tms;
 528	}
 529
 530	ret = __tree_mod_log_insert(eb->fs_info, tm);
 531	if (ret)
 532		goto free_tms;
 533	write_unlock(&eb->fs_info->tree_mod_log_lock);
 534	kfree(tm_list);
 535
 536	return 0;
 537free_tms:
 538	for (i = 0; i < nr_items; i++) {
 539		if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
 540			rb_erase(&tm_list[i]->node, &eb->fs_info->tree_mod_log);
 541		kfree(tm_list[i]);
 542	}
 543	if (locked)
 544		write_unlock(&eb->fs_info->tree_mod_log_lock);
 545	kfree(tm_list);
 546	kfree(tm);
 547
 548	return ret;
 549}
 550
 551static inline int
 552__tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
 553		       struct tree_mod_elem **tm_list,
 554		       int nritems)
 555{
 556	int i, j;
 557	int ret;
 558
 559	for (i = nritems - 1; i >= 0; i--) {
 560		ret = __tree_mod_log_insert(fs_info, tm_list[i]);
 561		if (ret) {
 562			for (j = nritems - 1; j > i; j--)
 563				rb_erase(&tm_list[j]->node,
 564					 &fs_info->tree_mod_log);
 565			return ret;
 566		}
 567	}
 568
 569	return 0;
 570}
 571
 572static noinline int tree_mod_log_insert_root(struct extent_buffer *old_root,
 573			 struct extent_buffer *new_root, int log_removal)
 
 
 
 574{
 575	struct btrfs_fs_info *fs_info = old_root->fs_info;
 576	struct tree_mod_elem *tm = NULL;
 577	struct tree_mod_elem **tm_list = NULL;
 578	int nritems = 0;
 579	int ret = 0;
 580	int i;
 581
 582	if (!tree_mod_need_log(fs_info, NULL))
 583		return 0;
 584
 585	if (log_removal && btrfs_header_level(old_root) > 0) {
 586		nritems = btrfs_header_nritems(old_root);
 587		tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *),
 588				  GFP_NOFS);
 589		if (!tm_list) {
 590			ret = -ENOMEM;
 591			goto free_tms;
 592		}
 593		for (i = 0; i < nritems; i++) {
 594			tm_list[i] = alloc_tree_mod_elem(old_root, i,
 595			    MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
 596			if (!tm_list[i]) {
 597				ret = -ENOMEM;
 598				goto free_tms;
 599			}
 600		}
 601	}
 602
 603	tm = kzalloc(sizeof(*tm), GFP_NOFS);
 604	if (!tm) {
 605		ret = -ENOMEM;
 606		goto free_tms;
 607	}
 608
 609	tm->logical = new_root->start;
 610	tm->old_root.logical = old_root->start;
 611	tm->old_root.level = btrfs_header_level(old_root);
 612	tm->generation = btrfs_header_generation(old_root);
 613	tm->op = MOD_LOG_ROOT_REPLACE;
 614
 615	if (tree_mod_dont_log(fs_info, NULL))
 616		goto free_tms;
 617
 618	if (tm_list)
 619		ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
 620	if (!ret)
 621		ret = __tree_mod_log_insert(fs_info, tm);
 622
 623	write_unlock(&fs_info->tree_mod_log_lock);
 624	if (ret)
 625		goto free_tms;
 626	kfree(tm_list);
 627
 628	return ret;
 629
 630free_tms:
 631	if (tm_list) {
 632		for (i = 0; i < nritems; i++)
 633			kfree(tm_list[i]);
 634		kfree(tm_list);
 635	}
 636	kfree(tm);
 637
 638	return ret;
 639}
 640
 641static struct tree_mod_elem *
 642__tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
 643		      int smallest)
 644{
 645	struct rb_root *tm_root;
 646	struct rb_node *node;
 647	struct tree_mod_elem *cur = NULL;
 648	struct tree_mod_elem *found = NULL;
 649
 650	read_lock(&fs_info->tree_mod_log_lock);
 651	tm_root = &fs_info->tree_mod_log;
 652	node = tm_root->rb_node;
 653	while (node) {
 654		cur = rb_entry(node, struct tree_mod_elem, node);
 655		if (cur->logical < start) {
 656			node = node->rb_left;
 657		} else if (cur->logical > start) {
 658			node = node->rb_right;
 659		} else if (cur->seq < min_seq) {
 660			node = node->rb_left;
 661		} else if (!smallest) {
 662			/* we want the node with the highest seq */
 663			if (found)
 664				BUG_ON(found->seq > cur->seq);
 665			found = cur;
 666			node = node->rb_left;
 667		} else if (cur->seq > min_seq) {
 668			/* we want the node with the smallest seq */
 669			if (found)
 670				BUG_ON(found->seq < cur->seq);
 671			found = cur;
 672			node = node->rb_right;
 673		} else {
 674			found = cur;
 675			break;
 676		}
 677	}
 678	read_unlock(&fs_info->tree_mod_log_lock);
 679
 680	return found;
 681}
 682
 683/*
 684 * this returns the element from the log with the smallest time sequence
 685 * value that's in the log (the oldest log item). any element with a time
 686 * sequence lower than min_seq will be ignored.
 687 */
 688static struct tree_mod_elem *
 689tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
 690			   u64 min_seq)
 691{
 692	return __tree_mod_log_search(fs_info, start, min_seq, 1);
 693}
 694
 695/*
 696 * this returns the element from the log with the largest time sequence
 697 * value that's in the log (the most recent log item). any element with
 698 * a time sequence lower than min_seq will be ignored.
 699 */
 700static struct tree_mod_elem *
 701tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
 702{
 703	return __tree_mod_log_search(fs_info, start, min_seq, 0);
 704}
 705
 706static noinline int tree_mod_log_eb_copy(struct extent_buffer *dst,
 
 707		     struct extent_buffer *src, unsigned long dst_offset,
 708		     unsigned long src_offset, int nr_items)
 709{
 710	struct btrfs_fs_info *fs_info = dst->fs_info;
 711	int ret = 0;
 712	struct tree_mod_elem **tm_list = NULL;
 713	struct tree_mod_elem **tm_list_add, **tm_list_rem;
 714	int i;
 715	int locked = 0;
 716
 717	if (!tree_mod_need_log(fs_info, NULL))
 718		return 0;
 719
 720	if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
 721		return 0;
 722
 723	tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *),
 724			  GFP_NOFS);
 725	if (!tm_list)
 726		return -ENOMEM;
 727
 728	tm_list_add = tm_list;
 729	tm_list_rem = tm_list + nr_items;
 730	for (i = 0; i < nr_items; i++) {
 731		tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
 732		    MOD_LOG_KEY_REMOVE, GFP_NOFS);
 733		if (!tm_list_rem[i]) {
 734			ret = -ENOMEM;
 735			goto free_tms;
 736		}
 737
 738		tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
 739		    MOD_LOG_KEY_ADD, GFP_NOFS);
 740		if (!tm_list_add[i]) {
 741			ret = -ENOMEM;
 742			goto free_tms;
 743		}
 744	}
 745
 746	if (tree_mod_dont_log(fs_info, NULL))
 747		goto free_tms;
 748	locked = 1;
 749
 750	for (i = 0; i < nr_items; i++) {
 751		ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
 752		if (ret)
 753			goto free_tms;
 754		ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
 755		if (ret)
 756			goto free_tms;
 757	}
 758
 759	write_unlock(&fs_info->tree_mod_log_lock);
 760	kfree(tm_list);
 761
 762	return 0;
 763
 764free_tms:
 765	for (i = 0; i < nr_items * 2; i++) {
 766		if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
 767			rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
 768		kfree(tm_list[i]);
 769	}
 770	if (locked)
 771		write_unlock(&fs_info->tree_mod_log_lock);
 772	kfree(tm_list);
 773
 774	return ret;
 775}
 776
 777static noinline int tree_mod_log_free_eb(struct extent_buffer *eb)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 778{
 779	struct tree_mod_elem **tm_list = NULL;
 780	int nritems = 0;
 781	int i;
 782	int ret = 0;
 783
 784	if (btrfs_header_level(eb) == 0)
 785		return 0;
 786
 787	if (!tree_mod_need_log(eb->fs_info, NULL))
 788		return 0;
 789
 790	nritems = btrfs_header_nritems(eb);
 791	tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS);
 792	if (!tm_list)
 793		return -ENOMEM;
 794
 795	for (i = 0; i < nritems; i++) {
 796		tm_list[i] = alloc_tree_mod_elem(eb, i,
 797		    MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
 798		if (!tm_list[i]) {
 799			ret = -ENOMEM;
 800			goto free_tms;
 801		}
 802	}
 803
 804	if (tree_mod_dont_log(eb->fs_info, eb))
 805		goto free_tms;
 806
 807	ret = __tree_mod_log_free_eb(eb->fs_info, tm_list, nritems);
 808	write_unlock(&eb->fs_info->tree_mod_log_lock);
 809	if (ret)
 810		goto free_tms;
 811	kfree(tm_list);
 812
 813	return 0;
 814
 815free_tms:
 816	for (i = 0; i < nritems; i++)
 817		kfree(tm_list[i]);
 818	kfree(tm_list);
 819
 820	return ret;
 821}
 822
 
 
 
 
 
 
 
 
 
 
 
 823/*
 824 * check if the tree block can be shared by multiple trees
 825 */
 826int btrfs_block_can_be_shared(struct btrfs_root *root,
 827			      struct extent_buffer *buf)
 828{
 829	/*
 830	 * Tree blocks not in shareable trees and tree roots are never shared.
 831	 * If a block was allocated after the last snapshot and the block was
 832	 * not allocated by tree relocation, we know the block is not shared.
 
 833	 */
 834	if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 835	    buf != root->node && buf != root->commit_root &&
 836	    (btrfs_header_generation(buf) <=
 837	     btrfs_root_last_snapshot(&root->root_item) ||
 838	     btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 839		return 1;
 840
 
 
 
 
 841	return 0;
 842}
 843
 844static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 845				       struct btrfs_root *root,
 846				       struct extent_buffer *buf,
 847				       struct extent_buffer *cow,
 848				       int *last_ref)
 849{
 850	struct btrfs_fs_info *fs_info = root->fs_info;
 851	u64 refs;
 852	u64 owner;
 853	u64 flags;
 854	u64 new_flags = 0;
 855	int ret;
 856
 857	/*
 858	 * Backrefs update rules:
 859	 *
 860	 * Always use full backrefs for extent pointers in tree block
 861	 * allocated by tree relocation.
 862	 *
 863	 * If a shared tree block is no longer referenced by its owner
 864	 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 865	 * use full backrefs for extent pointers in tree block.
 866	 *
 867	 * If a tree block is been relocating
 868	 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
 869	 * use full backrefs for extent pointers in tree block.
 870	 * The reason for this is some operations (such as drop tree)
 871	 * are only allowed for blocks use full backrefs.
 872	 */
 873
 874	if (btrfs_block_can_be_shared(root, buf)) {
 875		ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
 876					       btrfs_header_level(buf), 1,
 877					       &refs, &flags);
 878		if (ret)
 879			return ret;
 880		if (refs == 0) {
 881			ret = -EROFS;
 882			btrfs_handle_fs_error(fs_info, ret, NULL);
 883			return ret;
 884		}
 885	} else {
 886		refs = 1;
 887		if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 888		    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 889			flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
 890		else
 891			flags = 0;
 892	}
 893
 894	owner = btrfs_header_owner(buf);
 895	BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
 896	       !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
 897
 898	if (refs > 1) {
 899		if ((owner == root->root_key.objectid ||
 900		     root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 901		    !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 902			ret = btrfs_inc_ref(trans, root, buf, 1);
 903			if (ret)
 904				return ret;
 905
 906			if (root->root_key.objectid ==
 907			    BTRFS_TREE_RELOC_OBJECTID) {
 908				ret = btrfs_dec_ref(trans, root, buf, 0);
 909				if (ret)
 910					return ret;
 911				ret = btrfs_inc_ref(trans, root, cow, 1);
 912				if (ret)
 913					return ret;
 914			}
 915			new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 916		} else {
 917
 918			if (root->root_key.objectid ==
 919			    BTRFS_TREE_RELOC_OBJECTID)
 920				ret = btrfs_inc_ref(trans, root, cow, 1);
 921			else
 922				ret = btrfs_inc_ref(trans, root, cow, 0);
 923			if (ret)
 924				return ret;
 925		}
 926		if (new_flags != 0) {
 927			int level = btrfs_header_level(buf);
 928
 929			ret = btrfs_set_disk_extent_flags(trans, buf,
 
 
 930							  new_flags, level, 0);
 931			if (ret)
 932				return ret;
 933		}
 934	} else {
 935		if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
 936			if (root->root_key.objectid ==
 937			    BTRFS_TREE_RELOC_OBJECTID)
 938				ret = btrfs_inc_ref(trans, root, cow, 1);
 939			else
 940				ret = btrfs_inc_ref(trans, root, cow, 0);
 941			if (ret)
 942				return ret;
 943			ret = btrfs_dec_ref(trans, root, buf, 1);
 944			if (ret)
 945				return ret;
 946		}
 947		btrfs_clean_tree_block(buf);
 948		*last_ref = 1;
 949	}
 950	return 0;
 951}
 952
 953static struct extent_buffer *alloc_tree_block_no_bg_flush(
 954					  struct btrfs_trans_handle *trans,
 955					  struct btrfs_root *root,
 956					  u64 parent_start,
 957					  const struct btrfs_disk_key *disk_key,
 958					  int level,
 959					  u64 hint,
 960					  u64 empty_size)
 961{
 962	struct btrfs_fs_info *fs_info = root->fs_info;
 963	struct extent_buffer *ret;
 964
 965	/*
 966	 * If we are COWing a node/leaf from the extent, chunk, device or free
 967	 * space trees, make sure that we do not finish block group creation of
 968	 * pending block groups. We do this to avoid a deadlock.
 969	 * COWing can result in allocation of a new chunk, and flushing pending
 970	 * block groups (btrfs_create_pending_block_groups()) can be triggered
 971	 * when finishing allocation of a new chunk. Creation of a pending block
 972	 * group modifies the extent, chunk, device and free space trees,
 973	 * therefore we could deadlock with ourselves since we are holding a
 974	 * lock on an extent buffer that btrfs_create_pending_block_groups() may
 975	 * try to COW later.
 976	 * For similar reasons, we also need to delay flushing pending block
 977	 * groups when splitting a leaf or node, from one of those trees, since
 978	 * we are holding a write lock on it and its parent or when inserting a
 979	 * new root node for one of those trees.
 980	 */
 981	if (root == fs_info->extent_root ||
 982	    root == fs_info->chunk_root ||
 983	    root == fs_info->dev_root ||
 984	    root == fs_info->free_space_root)
 985		trans->can_flush_pending_bgs = false;
 986
 987	ret = btrfs_alloc_tree_block(trans, root, parent_start,
 988				     root->root_key.objectid, disk_key, level,
 989				     hint, empty_size);
 990	trans->can_flush_pending_bgs = true;
 991
 992	return ret;
 993}
 994
 995/*
 996 * does the dirty work in cow of a single block.  The parent block (if
 997 * supplied) is updated to point to the new cow copy.  The new buffer is marked
 998 * dirty and returned locked.  If you modify the block it needs to be marked
 999 * dirty again.
1000 *
1001 * search_start -- an allocation hint for the new block
1002 *
1003 * empty_size -- a hint that you plan on doing more cow.  This is the size in
1004 * bytes the allocator should try to find free next to the block it returns.
1005 * This is just a hint and may be ignored by the allocator.
1006 */
1007static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
1008			     struct btrfs_root *root,
1009			     struct extent_buffer *buf,
1010			     struct extent_buffer *parent, int parent_slot,
1011			     struct extent_buffer **cow_ret,
1012			     u64 search_start, u64 empty_size)
1013{
1014	struct btrfs_fs_info *fs_info = root->fs_info;
1015	struct btrfs_disk_key disk_key;
1016	struct extent_buffer *cow;
1017	int level, ret;
1018	int last_ref = 0;
1019	int unlock_orig = 0;
1020	u64 parent_start = 0;
1021
1022	if (*cow_ret == buf)
1023		unlock_orig = 1;
1024
1025	btrfs_assert_tree_locked(buf);
1026
1027	WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
1028		trans->transid != fs_info->running_transaction->transid);
1029	WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
1030		trans->transid != root->last_trans);
1031
1032	level = btrfs_header_level(buf);
1033
1034	if (level == 0)
1035		btrfs_item_key(buf, &disk_key, 0);
1036	else
1037		btrfs_node_key(buf, &disk_key, 0);
1038
1039	if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
1040		parent_start = parent->start;
 
 
 
 
 
1041
1042	cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
1043					   level, search_start, empty_size);
 
1044	if (IS_ERR(cow))
1045		return PTR_ERR(cow);
1046
1047	/* cow is set to blocking by btrfs_init_new_buffer */
1048
1049	copy_extent_buffer_full(cow, buf);
1050	btrfs_set_header_bytenr(cow, cow->start);
1051	btrfs_set_header_generation(cow, trans->transid);
1052	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1053	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1054				     BTRFS_HEADER_FLAG_RELOC);
1055	if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1056		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1057	else
1058		btrfs_set_header_owner(cow, root->root_key.objectid);
1059
1060	write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
 
1061
1062	ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1063	if (ret) {
1064		btrfs_abort_transaction(trans, ret);
1065		return ret;
1066	}
1067
1068	if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
1069		ret = btrfs_reloc_cow_block(trans, root, buf, cow);
1070		if (ret) {
1071			btrfs_abort_transaction(trans, ret);
1072			return ret;
1073		}
1074	}
1075
1076	if (buf == root->node) {
1077		WARN_ON(parent && parent != buf);
1078		if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1079		    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1080			parent_start = buf->start;
 
 
1081
1082		atomic_inc(&cow->refs);
1083		ret = tree_mod_log_insert_root(root->node, cow, 1);
1084		BUG_ON(ret < 0);
1085		rcu_assign_pointer(root->node, cow);
1086
1087		btrfs_free_tree_block(trans, root, buf, parent_start,
1088				      last_ref);
1089		free_extent_buffer(buf);
1090		add_root_to_dirty_list(root);
1091	} else {
 
 
 
 
 
1092		WARN_ON(trans->transid != btrfs_header_generation(parent));
1093		tree_mod_log_insert_key(parent, parent_slot,
1094					MOD_LOG_KEY_REPLACE, GFP_NOFS);
1095		btrfs_set_node_blockptr(parent, parent_slot,
1096					cow->start);
1097		btrfs_set_node_ptr_generation(parent, parent_slot,
1098					      trans->transid);
1099		btrfs_mark_buffer_dirty(parent);
1100		if (last_ref) {
1101			ret = tree_mod_log_free_eb(buf);
1102			if (ret) {
1103				btrfs_abort_transaction(trans, ret);
1104				return ret;
1105			}
1106		}
1107		btrfs_free_tree_block(trans, root, buf, parent_start,
1108				      last_ref);
1109	}
1110	if (unlock_orig)
1111		btrfs_tree_unlock(buf);
1112	free_extent_buffer_stale(buf);
1113	btrfs_mark_buffer_dirty(cow);
1114	*cow_ret = cow;
1115	return 0;
1116}
1117
1118/*
1119 * returns the logical address of the oldest predecessor of the given root.
1120 * entries older than time_seq are ignored.
1121 */
1122static struct tree_mod_elem *__tree_mod_log_oldest_root(
1123		struct extent_buffer *eb_root, u64 time_seq)
 
1124{
1125	struct tree_mod_elem *tm;
1126	struct tree_mod_elem *found = NULL;
1127	u64 root_logical = eb_root->start;
1128	int looped = 0;
1129
1130	if (!time_seq)
1131		return NULL;
1132
1133	/*
1134	 * the very last operation that's logged for a root is the
1135	 * replacement operation (if it is replaced at all). this has
1136	 * the logical address of the *new* root, making it the very
1137	 * first operation that's logged for this root.
1138	 */
1139	while (1) {
1140		tm = tree_mod_log_search_oldest(eb_root->fs_info, root_logical,
1141						time_seq);
1142		if (!looped && !tm)
1143			return NULL;
1144		/*
1145		 * if there are no tree operation for the oldest root, we simply
1146		 * return it. this should only happen if that (old) root is at
1147		 * level 0.
1148		 */
1149		if (!tm)
1150			break;
1151
1152		/*
1153		 * if there's an operation that's not a root replacement, we
1154		 * found the oldest version of our root. normally, we'll find a
1155		 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1156		 */
1157		if (tm->op != MOD_LOG_ROOT_REPLACE)
1158			break;
1159
1160		found = tm;
1161		root_logical = tm->old_root.logical;
1162		looped = 1;
1163	}
1164
1165	/* if there's no old root to return, return what we found instead */
1166	if (!found)
1167		found = tm;
1168
1169	return found;
1170}
1171
1172/*
1173 * tm is a pointer to the first operation to rewind within eb. then, all
1174 * previous operations will be rewound (until we reach something older than
1175 * time_seq).
1176 */
1177static void
1178__tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1179		      u64 time_seq, struct tree_mod_elem *first_tm)
1180{
1181	u32 n;
1182	struct rb_node *next;
1183	struct tree_mod_elem *tm = first_tm;
1184	unsigned long o_dst;
1185	unsigned long o_src;
1186	unsigned long p_size = sizeof(struct btrfs_key_ptr);
1187
1188	n = btrfs_header_nritems(eb);
1189	read_lock(&fs_info->tree_mod_log_lock);
1190	while (tm && tm->seq >= time_seq) {
1191		/*
1192		 * all the operations are recorded with the operator used for
1193		 * the modification. as we're going backwards, we do the
1194		 * opposite of each operation here.
1195		 */
1196		switch (tm->op) {
1197		case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1198			BUG_ON(tm->slot < n);
1199			fallthrough;
1200		case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1201		case MOD_LOG_KEY_REMOVE:
1202			btrfs_set_node_key(eb, &tm->key, tm->slot);
1203			btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1204			btrfs_set_node_ptr_generation(eb, tm->slot,
1205						      tm->generation);
1206			n++;
1207			break;
1208		case MOD_LOG_KEY_REPLACE:
1209			BUG_ON(tm->slot >= n);
1210			btrfs_set_node_key(eb, &tm->key, tm->slot);
1211			btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1212			btrfs_set_node_ptr_generation(eb, tm->slot,
1213						      tm->generation);
1214			break;
1215		case MOD_LOG_KEY_ADD:
1216			/* if a move operation is needed it's in the log */
1217			n--;
1218			break;
1219		case MOD_LOG_MOVE_KEYS:
1220			o_dst = btrfs_node_key_ptr_offset(tm->slot);
1221			o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1222			memmove_extent_buffer(eb, o_dst, o_src,
1223					      tm->move.nr_items * p_size);
1224			break;
1225		case MOD_LOG_ROOT_REPLACE:
1226			/*
1227			 * this operation is special. for roots, this must be
1228			 * handled explicitly before rewinding.
1229			 * for non-roots, this operation may exist if the node
1230			 * was a root: root A -> child B; then A gets empty and
1231			 * B is promoted to the new root. in the mod log, we'll
1232			 * have a root-replace operation for B, a tree block
1233			 * that is no root. we simply ignore that operation.
1234			 */
1235			break;
1236		}
1237		next = rb_next(&tm->node);
1238		if (!next)
1239			break;
1240		tm = rb_entry(next, struct tree_mod_elem, node);
1241		if (tm->logical != first_tm->logical)
1242			break;
1243	}
1244	read_unlock(&fs_info->tree_mod_log_lock);
1245	btrfs_set_header_nritems(eb, n);
1246}
1247
1248/*
1249 * Called with eb read locked. If the buffer cannot be rewound, the same buffer
1250 * is returned. If rewind operations happen, a fresh buffer is returned. The
1251 * returned buffer is always read-locked. If the returned buffer is not the
1252 * input buffer, the lock on the input buffer is released and the input buffer
1253 * is freed (its refcount is decremented).
1254 */
1255static struct extent_buffer *
1256tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
1257		    struct extent_buffer *eb, u64 time_seq)
1258{
1259	struct extent_buffer *eb_rewin;
1260	struct tree_mod_elem *tm;
1261
1262	if (!time_seq)
1263		return eb;
1264
1265	if (btrfs_header_level(eb) == 0)
1266		return eb;
1267
1268	tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1269	if (!tm)
1270		return eb;
1271
1272	btrfs_set_path_blocking(path);
1273	btrfs_set_lock_blocking_read(eb);
1274
1275	if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1276		BUG_ON(tm->slot != 0);
1277		eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
1278		if (!eb_rewin) {
1279			btrfs_tree_read_unlock_blocking(eb);
1280			free_extent_buffer(eb);
1281			return NULL;
1282		}
1283		btrfs_set_header_bytenr(eb_rewin, eb->start);
1284		btrfs_set_header_backref_rev(eb_rewin,
1285					     btrfs_header_backref_rev(eb));
1286		btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1287		btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1288	} else {
1289		eb_rewin = btrfs_clone_extent_buffer(eb);
1290		if (!eb_rewin) {
1291			btrfs_tree_read_unlock_blocking(eb);
1292			free_extent_buffer(eb);
1293			return NULL;
1294		}
1295	}
1296
 
1297	btrfs_tree_read_unlock_blocking(eb);
1298	free_extent_buffer(eb);
1299
1300	btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb_rewin),
1301				       eb_rewin, btrfs_header_level(eb_rewin));
1302	btrfs_tree_read_lock(eb_rewin);
1303	__tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
1304	WARN_ON(btrfs_header_nritems(eb_rewin) >
1305		BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1306
1307	return eb_rewin;
1308}
1309
1310/*
1311 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1312 * value. If there are no changes, the current root->root_node is returned. If
1313 * anything changed in between, there's a fresh buffer allocated on which the
1314 * rewind operations are done. In any case, the returned buffer is read locked.
1315 * Returns NULL on error (with no locks held).
1316 */
1317static inline struct extent_buffer *
1318get_old_root(struct btrfs_root *root, u64 time_seq)
1319{
1320	struct btrfs_fs_info *fs_info = root->fs_info;
1321	struct tree_mod_elem *tm;
1322	struct extent_buffer *eb = NULL;
1323	struct extent_buffer *eb_root;
1324	u64 eb_root_owner = 0;
1325	struct extent_buffer *old;
1326	struct tree_mod_root *old_root = NULL;
1327	u64 old_generation = 0;
1328	u64 logical;
1329	int level;
1330
1331	eb_root = btrfs_read_lock_root_node(root);
1332	tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1333	if (!tm)
1334		return eb_root;
1335
1336	if (tm->op == MOD_LOG_ROOT_REPLACE) {
1337		old_root = &tm->old_root;
1338		old_generation = tm->generation;
1339		logical = old_root->logical;
1340		level = old_root->level;
1341	} else {
1342		logical = eb_root->start;
1343		level = btrfs_header_level(eb_root);
1344	}
1345
1346	tm = tree_mod_log_search(fs_info, logical, time_seq);
1347	if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1348		btrfs_tree_read_unlock(eb_root);
1349		free_extent_buffer(eb_root);
1350		old = read_tree_block(fs_info, logical, 0, level, NULL);
1351		if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) {
1352			if (!IS_ERR(old))
1353				free_extent_buffer(old);
1354			btrfs_warn(fs_info,
1355				   "failed to read tree block %llu from get_old_root",
1356				   logical);
1357		} else {
1358			eb = btrfs_clone_extent_buffer(old);
1359			free_extent_buffer(old);
1360		}
1361	} else if (old_root) {
1362		eb_root_owner = btrfs_header_owner(eb_root);
1363		btrfs_tree_read_unlock(eb_root);
1364		free_extent_buffer(eb_root);
1365		eb = alloc_dummy_extent_buffer(fs_info, logical);
1366	} else {
1367		btrfs_set_lock_blocking_read(eb_root);
1368		eb = btrfs_clone_extent_buffer(eb_root);
1369		btrfs_tree_read_unlock_blocking(eb_root);
1370		free_extent_buffer(eb_root);
1371	}
1372
1373	if (!eb)
1374		return NULL;
 
 
1375	if (old_root) {
1376		btrfs_set_header_bytenr(eb, eb->start);
1377		btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1378		btrfs_set_header_owner(eb, eb_root_owner);
1379		btrfs_set_header_level(eb, old_root->level);
1380		btrfs_set_header_generation(eb, old_generation);
1381	}
1382	btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb), eb,
1383				       btrfs_header_level(eb));
1384	btrfs_tree_read_lock(eb);
1385	if (tm)
1386		__tree_mod_log_rewind(fs_info, eb, time_seq, tm);
1387	else
1388		WARN_ON(btrfs_header_level(eb) != 0);
1389	WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1390
1391	return eb;
1392}
1393
1394int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1395{
1396	struct tree_mod_elem *tm;
1397	int level;
1398	struct extent_buffer *eb_root = btrfs_root_node(root);
1399
1400	tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1401	if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1402		level = tm->old_root.level;
1403	} else {
1404		level = btrfs_header_level(eb_root);
1405	}
1406	free_extent_buffer(eb_root);
1407
1408	return level;
1409}
1410
1411static inline int should_cow_block(struct btrfs_trans_handle *trans,
1412				   struct btrfs_root *root,
1413				   struct extent_buffer *buf)
1414{
1415	if (btrfs_is_testing(root->fs_info))
1416		return 0;
1417
1418	/* Ensure we can see the FORCE_COW bit */
1419	smp_mb__before_atomic();
1420
1421	/*
1422	 * We do not need to cow a block if
1423	 * 1) this block is not created or changed in this transaction;
1424	 * 2) this block does not belong to TREE_RELOC tree;
1425	 * 3) the root is not forced COW.
1426	 *
1427	 * What is forced COW:
1428	 *    when we create snapshot during committing the transaction,
1429	 *    after we've finished copying src root, we must COW the shared
1430	 *    block to ensure the metadata consistency.
1431	 */
1432	if (btrfs_header_generation(buf) == trans->transid &&
1433	    !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1434	    !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1435	      btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1436	    !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
1437		return 0;
1438	return 1;
1439}
1440
1441/*
1442 * cows a single block, see __btrfs_cow_block for the real work.
1443 * This version of it has extra checks so that a block isn't COWed more than
1444 * once per transaction, as long as it hasn't been written yet
1445 */
1446noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1447		    struct btrfs_root *root, struct extent_buffer *buf,
1448		    struct extent_buffer *parent, int parent_slot,
1449		    struct extent_buffer **cow_ret)
1450{
1451	struct btrfs_fs_info *fs_info = root->fs_info;
1452	u64 search_start;
1453	int ret;
1454
1455	if (test_bit(BTRFS_ROOT_DELETING, &root->state))
1456		btrfs_err(fs_info,
1457			"COW'ing blocks on a fs root that's being dropped");
1458
1459	if (trans->transaction != fs_info->running_transaction)
1460		WARN(1, KERN_CRIT "trans %llu running %llu\n",
1461		       trans->transid,
1462		       fs_info->running_transaction->transid);
1463
1464	if (trans->transid != fs_info->generation)
1465		WARN(1, KERN_CRIT "trans %llu running %llu\n",
1466		       trans->transid, fs_info->generation);
1467
1468	if (!should_cow_block(trans, root, buf)) {
1469		trans->dirty = true;
1470		*cow_ret = buf;
1471		return 0;
1472	}
1473
1474	search_start = buf->start & ~((u64)SZ_1G - 1);
1475
1476	if (parent)
1477		btrfs_set_lock_blocking_write(parent);
1478	btrfs_set_lock_blocking_write(buf);
1479
1480	/*
1481	 * Before CoWing this block for later modification, check if it's
1482	 * the subtree root and do the delayed subtree trace if needed.
1483	 *
1484	 * Also We don't care about the error, as it's handled internally.
1485	 */
1486	btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
1487	ret = __btrfs_cow_block(trans, root, buf, parent,
1488				 parent_slot, cow_ret, search_start, 0);
1489
1490	trace_btrfs_cow_block(root, buf, *cow_ret);
1491
1492	return ret;
1493}
1494
1495/*
1496 * helper function for defrag to decide if two blocks pointed to by a
1497 * node are actually close by
1498 */
1499static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1500{
1501	if (blocknr < other && other - (blocknr + blocksize) < 32768)
1502		return 1;
1503	if (blocknr > other && blocknr - (other + blocksize) < 32768)
1504		return 1;
1505	return 0;
1506}
1507
1508#ifdef __LITTLE_ENDIAN
1509
1510/*
1511 * Compare two keys, on little-endian the disk order is same as CPU order and
1512 * we can avoid the conversion.
1513 */
1514static int comp_keys(const struct btrfs_disk_key *disk_key,
1515		     const struct btrfs_key *k2)
1516{
1517	const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key;
1518
1519	return btrfs_comp_cpu_keys(k1, k2);
1520}
1521
1522#else
1523
1524/*
1525 * compare two keys in a memcmp fashion
1526 */
1527static int comp_keys(const struct btrfs_disk_key *disk,
1528		     const struct btrfs_key *k2)
1529{
1530	struct btrfs_key k1;
1531
1532	btrfs_disk_key_to_cpu(&k1, disk);
1533
1534	return btrfs_comp_cpu_keys(&k1, k2);
1535}
1536#endif
1537
1538/*
1539 * same as comp_keys only with two btrfs_key's
1540 */
1541int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
1542{
1543	if (k1->objectid > k2->objectid)
1544		return 1;
1545	if (k1->objectid < k2->objectid)
1546		return -1;
1547	if (k1->type > k2->type)
1548		return 1;
1549	if (k1->type < k2->type)
1550		return -1;
1551	if (k1->offset > k2->offset)
1552		return 1;
1553	if (k1->offset < k2->offset)
1554		return -1;
1555	return 0;
1556}
1557
1558/*
1559 * this is used by the defrag code to go through all the
1560 * leaves pointed to by a node and reallocate them so that
1561 * disk order is close to key order
1562 */
1563int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1564		       struct btrfs_root *root, struct extent_buffer *parent,
1565		       int start_slot, u64 *last_ret,
1566		       struct btrfs_key *progress)
1567{
1568	struct btrfs_fs_info *fs_info = root->fs_info;
1569	struct extent_buffer *cur;
1570	u64 blocknr;
1571	u64 gen;
1572	u64 search_start = *last_ret;
1573	u64 last_block = 0;
1574	u64 other;
1575	u32 parent_nritems;
1576	int end_slot;
1577	int i;
1578	int err = 0;
1579	int parent_level;
1580	int uptodate;
1581	u32 blocksize;
1582	int progress_passed = 0;
1583	struct btrfs_disk_key disk_key;
1584
1585	parent_level = btrfs_header_level(parent);
1586
1587	WARN_ON(trans->transaction != fs_info->running_transaction);
1588	WARN_ON(trans->transid != fs_info->generation);
1589
1590	parent_nritems = btrfs_header_nritems(parent);
1591	blocksize = fs_info->nodesize;
1592	end_slot = parent_nritems - 1;
1593
1594	if (parent_nritems <= 1)
1595		return 0;
1596
1597	btrfs_set_lock_blocking_write(parent);
1598
1599	for (i = start_slot; i <= end_slot; i++) {
1600		struct btrfs_key first_key;
1601		int close = 1;
1602
1603		btrfs_node_key(parent, &disk_key, i);
1604		if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1605			continue;
1606
1607		progress_passed = 1;
1608		blocknr = btrfs_node_blockptr(parent, i);
1609		gen = btrfs_node_ptr_generation(parent, i);
1610		btrfs_node_key_to_cpu(parent, &first_key, i);
1611		if (last_block == 0)
1612			last_block = blocknr;
1613
1614		if (i > 0) {
1615			other = btrfs_node_blockptr(parent, i - 1);
1616			close = close_blocks(blocknr, other, blocksize);
1617		}
1618		if (!close && i < end_slot) {
1619			other = btrfs_node_blockptr(parent, i + 1);
1620			close = close_blocks(blocknr, other, blocksize);
1621		}
1622		if (close) {
1623			last_block = blocknr;
1624			continue;
1625		}
1626
1627		cur = find_extent_buffer(fs_info, blocknr);
1628		if (cur)
1629			uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1630		else
1631			uptodate = 0;
1632		if (!cur || !uptodate) {
1633			if (!cur) {
1634				cur = read_tree_block(fs_info, blocknr, gen,
1635						      parent_level - 1,
1636						      &first_key);
1637				if (IS_ERR(cur)) {
1638					return PTR_ERR(cur);
1639				} else if (!extent_buffer_uptodate(cur)) {
1640					free_extent_buffer(cur);
1641					return -EIO;
1642				}
1643			} else if (!uptodate) {
1644				err = btrfs_read_buffer(cur, gen,
1645						parent_level - 1,&first_key);
1646				if (err) {
1647					free_extent_buffer(cur);
1648					return err;
1649				}
1650			}
1651		}
1652		if (search_start == 0)
1653			search_start = last_block;
1654
1655		btrfs_tree_lock(cur);
1656		btrfs_set_lock_blocking_write(cur);
1657		err = __btrfs_cow_block(trans, root, cur, parent, i,
1658					&cur, search_start,
1659					min(16 * blocksize,
1660					    (end_slot - i) * blocksize));
1661		if (err) {
1662			btrfs_tree_unlock(cur);
1663			free_extent_buffer(cur);
1664			break;
1665		}
1666		search_start = cur->start;
1667		last_block = cur->start;
1668		*last_ret = search_start;
1669		btrfs_tree_unlock(cur);
1670		free_extent_buffer(cur);
1671	}
1672	return err;
1673}
1674
1675/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1676 * search for key in the extent_buffer.  The items start at offset p,
1677 * and they are item_size apart.  There are 'max' items in p.
1678 *
1679 * the slot in the array is returned via slot, and it points to
1680 * the place where you would insert key if it is not found in
1681 * the array.
1682 *
1683 * slot may point to max if the key is bigger than all of the keys
1684 */
1685static noinline int generic_bin_search(struct extent_buffer *eb,
1686				       unsigned long p, int item_size,
1687				       const struct btrfs_key *key,
1688				       int max, int *slot)
1689{
1690	int low = 0;
1691	int high = max;
 
1692	int ret;
1693	const int key_size = sizeof(struct btrfs_disk_key);
1694
1695	if (low > high) {
1696		btrfs_err(eb->fs_info,
1697		 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
1698			  __func__, low, high, eb->start,
1699			  btrfs_header_owner(eb), btrfs_header_level(eb));
1700		return -EINVAL;
1701	}
1702
1703	while (low < high) {
1704		unsigned long oip;
1705		unsigned long offset;
1706		struct btrfs_disk_key *tmp;
1707		struct btrfs_disk_key unaligned;
1708		int mid;
1709
1710		mid = (low + high) / 2;
1711		offset = p + mid * item_size;
1712		oip = offset_in_page(offset);
1713
1714		if (oip + key_size <= PAGE_SIZE) {
1715			const unsigned long idx = offset >> PAGE_SHIFT;
1716			char *kaddr = page_address(eb->pages[idx]);
 
 
 
 
 
 
 
 
 
 
 
 
 
1717
1718			tmp = (struct btrfs_disk_key *)(kaddr + oip);
1719		} else {
1720			read_extent_buffer(eb, &unaligned, offset, key_size);
1721			tmp = &unaligned;
1722		}
1723
1724		ret = comp_keys(tmp, key);
1725
1726		if (ret < 0)
1727			low = mid + 1;
1728		else if (ret > 0)
1729			high = mid;
1730		else {
1731			*slot = mid;
1732			return 0;
1733		}
1734	}
1735	*slot = low;
1736	return 1;
1737}
1738
1739/*
1740 * simple bin_search frontend that does the right thing for
1741 * leaves vs nodes
1742 */
1743int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
1744		     int *slot)
1745{
1746	if (btrfs_header_level(eb) == 0)
1747		return generic_bin_search(eb,
1748					  offsetof(struct btrfs_leaf, items),
1749					  sizeof(struct btrfs_item),
1750					  key, btrfs_header_nritems(eb),
1751					  slot);
1752	else
1753		return generic_bin_search(eb,
1754					  offsetof(struct btrfs_node, ptrs),
1755					  sizeof(struct btrfs_key_ptr),
1756					  key, btrfs_header_nritems(eb),
1757					  slot);
1758}
1759
 
 
 
 
 
 
1760static void root_add_used(struct btrfs_root *root, u32 size)
1761{
1762	spin_lock(&root->accounting_lock);
1763	btrfs_set_root_used(&root->root_item,
1764			    btrfs_root_used(&root->root_item) + size);
1765	spin_unlock(&root->accounting_lock);
1766}
1767
1768static void root_sub_used(struct btrfs_root *root, u32 size)
1769{
1770	spin_lock(&root->accounting_lock);
1771	btrfs_set_root_used(&root->root_item,
1772			    btrfs_root_used(&root->root_item) - size);
1773	spin_unlock(&root->accounting_lock);
1774}
1775
1776/* given a node and slot number, this reads the blocks it points to.  The
1777 * extent buffer is returned with a reference taken (but unlocked).
 
1778 */
1779struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
1780					   int slot)
1781{
1782	int level = btrfs_header_level(parent);
1783	struct extent_buffer *eb;
1784	struct btrfs_key first_key;
1785
1786	if (slot < 0 || slot >= btrfs_header_nritems(parent))
1787		return ERR_PTR(-ENOENT);
 
 
1788
1789	BUG_ON(level == 0);
1790
1791	btrfs_node_key_to_cpu(parent, &first_key, slot);
1792	eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
1793			     btrfs_node_ptr_generation(parent, slot),
1794			     level - 1, &first_key);
1795	if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
1796		free_extent_buffer(eb);
1797		eb = ERR_PTR(-EIO);
1798	}
1799
1800	return eb;
1801}
1802
1803/*
1804 * node level balancing, used to make sure nodes are in proper order for
1805 * item deletion.  We balance from the top down, so we have to make sure
1806 * that a deletion won't leave an node completely empty later on.
1807 */
1808static noinline int balance_level(struct btrfs_trans_handle *trans,
1809			 struct btrfs_root *root,
1810			 struct btrfs_path *path, int level)
1811{
1812	struct btrfs_fs_info *fs_info = root->fs_info;
1813	struct extent_buffer *right = NULL;
1814	struct extent_buffer *mid;
1815	struct extent_buffer *left = NULL;
1816	struct extent_buffer *parent = NULL;
1817	int ret = 0;
1818	int wret;
1819	int pslot;
1820	int orig_slot = path->slots[level];
1821	u64 orig_ptr;
1822
1823	ASSERT(level > 0);
 
1824
1825	mid = path->nodes[level];
1826
1827	WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1828		path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1829	WARN_ON(btrfs_header_generation(mid) != trans->transid);
1830
1831	orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1832
1833	if (level < BTRFS_MAX_LEVEL - 1) {
1834		parent = path->nodes[level + 1];
1835		pslot = path->slots[level + 1];
1836	}
1837
1838	/*
1839	 * deal with the case where there is only one pointer in the root
1840	 * by promoting the node below to a root
1841	 */
1842	if (!parent) {
1843		struct extent_buffer *child;
1844
1845		if (btrfs_header_nritems(mid) != 1)
1846			return 0;
1847
1848		/* promote the child to a root */
1849		child = btrfs_read_node_slot(mid, 0);
1850		if (IS_ERR(child)) {
1851			ret = PTR_ERR(child);
1852			btrfs_handle_fs_error(fs_info, ret, NULL);
1853			goto enospc;
1854		}
1855
1856		btrfs_tree_lock(child);
1857		btrfs_set_lock_blocking_write(child);
1858		ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1859		if (ret) {
1860			btrfs_tree_unlock(child);
1861			free_extent_buffer(child);
1862			goto enospc;
1863		}
1864
1865		ret = tree_mod_log_insert_root(root->node, child, 1);
1866		BUG_ON(ret < 0);
1867		rcu_assign_pointer(root->node, child);
1868
1869		add_root_to_dirty_list(root);
1870		btrfs_tree_unlock(child);
1871
1872		path->locks[level] = 0;
1873		path->nodes[level] = NULL;
1874		btrfs_clean_tree_block(mid);
1875		btrfs_tree_unlock(mid);
1876		/* once for the path */
1877		free_extent_buffer(mid);
1878
1879		root_sub_used(root, mid->len);
1880		btrfs_free_tree_block(trans, root, mid, 0, 1);
1881		/* once for the root ptr */
1882		free_extent_buffer_stale(mid);
1883		return 0;
1884	}
1885	if (btrfs_header_nritems(mid) >
1886	    BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1887		return 0;
1888
1889	left = btrfs_read_node_slot(parent, pslot - 1);
1890	if (IS_ERR(left))
1891		left = NULL;
1892
1893	if (left) {
1894		btrfs_tree_lock(left);
1895		btrfs_set_lock_blocking_write(left);
1896		wret = btrfs_cow_block(trans, root, left,
1897				       parent, pslot - 1, &left);
1898		if (wret) {
1899			ret = wret;
1900			goto enospc;
1901		}
1902	}
1903
1904	right = btrfs_read_node_slot(parent, pslot + 1);
1905	if (IS_ERR(right))
1906		right = NULL;
1907
1908	if (right) {
1909		btrfs_tree_lock(right);
1910		btrfs_set_lock_blocking_write(right);
1911		wret = btrfs_cow_block(trans, root, right,
1912				       parent, pslot + 1, &right);
1913		if (wret) {
1914			ret = wret;
1915			goto enospc;
1916		}
1917	}
1918
1919	/* first, try to make some room in the middle buffer */
1920	if (left) {
1921		orig_slot += btrfs_header_nritems(left);
1922		wret = push_node_left(trans, left, mid, 1);
1923		if (wret < 0)
1924			ret = wret;
1925	}
1926
1927	/*
1928	 * then try to empty the right most buffer into the middle
1929	 */
1930	if (right) {
1931		wret = push_node_left(trans, mid, right, 1);
1932		if (wret < 0 && wret != -ENOSPC)
1933			ret = wret;
1934		if (btrfs_header_nritems(right) == 0) {
1935			btrfs_clean_tree_block(right);
1936			btrfs_tree_unlock(right);
1937			del_ptr(root, path, level + 1, pslot + 1);
1938			root_sub_used(root, right->len);
1939			btrfs_free_tree_block(trans, root, right, 0, 1);
1940			free_extent_buffer_stale(right);
1941			right = NULL;
1942		} else {
1943			struct btrfs_disk_key right_key;
1944			btrfs_node_key(right, &right_key, 0);
1945			ret = tree_mod_log_insert_key(parent, pslot + 1,
1946					MOD_LOG_KEY_REPLACE, GFP_NOFS);
1947			BUG_ON(ret < 0);
1948			btrfs_set_node_key(parent, &right_key, pslot + 1);
1949			btrfs_mark_buffer_dirty(parent);
1950		}
1951	}
1952	if (btrfs_header_nritems(mid) == 1) {
1953		/*
1954		 * we're not allowed to leave a node with one item in the
1955		 * tree during a delete.  A deletion from lower in the tree
1956		 * could try to delete the only pointer in this node.
1957		 * So, pull some keys from the left.
1958		 * There has to be a left pointer at this point because
1959		 * otherwise we would have pulled some pointers from the
1960		 * right
1961		 */
1962		if (!left) {
1963			ret = -EROFS;
1964			btrfs_handle_fs_error(fs_info, ret, NULL);
1965			goto enospc;
1966		}
1967		wret = balance_node_right(trans, mid, left);
1968		if (wret < 0) {
1969			ret = wret;
1970			goto enospc;
1971		}
1972		if (wret == 1) {
1973			wret = push_node_left(trans, left, mid, 1);
1974			if (wret < 0)
1975				ret = wret;
1976		}
1977		BUG_ON(wret == 1);
1978	}
1979	if (btrfs_header_nritems(mid) == 0) {
1980		btrfs_clean_tree_block(mid);
1981		btrfs_tree_unlock(mid);
1982		del_ptr(root, path, level + 1, pslot);
1983		root_sub_used(root, mid->len);
1984		btrfs_free_tree_block(trans, root, mid, 0, 1);
1985		free_extent_buffer_stale(mid);
1986		mid = NULL;
1987	} else {
1988		/* update the parent key to reflect our changes */
1989		struct btrfs_disk_key mid_key;
1990		btrfs_node_key(mid, &mid_key, 0);
1991		ret = tree_mod_log_insert_key(parent, pslot,
1992				MOD_LOG_KEY_REPLACE, GFP_NOFS);
1993		BUG_ON(ret < 0);
1994		btrfs_set_node_key(parent, &mid_key, pslot);
1995		btrfs_mark_buffer_dirty(parent);
1996	}
1997
1998	/* update the path */
1999	if (left) {
2000		if (btrfs_header_nritems(left) > orig_slot) {
2001			atomic_inc(&left->refs);
2002			/* left was locked after cow */
2003			path->nodes[level] = left;
2004			path->slots[level + 1] -= 1;
2005			path->slots[level] = orig_slot;
2006			if (mid) {
2007				btrfs_tree_unlock(mid);
2008				free_extent_buffer(mid);
2009			}
2010		} else {
2011			orig_slot -= btrfs_header_nritems(left);
2012			path->slots[level] = orig_slot;
2013		}
2014	}
2015	/* double check we haven't messed things up */
2016	if (orig_ptr !=
2017	    btrfs_node_blockptr(path->nodes[level], path->slots[level]))
2018		BUG();
2019enospc:
2020	if (right) {
2021		btrfs_tree_unlock(right);
2022		free_extent_buffer(right);
2023	}
2024	if (left) {
2025		if (path->nodes[level] != left)
2026			btrfs_tree_unlock(left);
2027		free_extent_buffer(left);
2028	}
2029	return ret;
2030}
2031
2032/* Node balancing for insertion.  Here we only split or push nodes around
2033 * when they are completely full.  This is also done top down, so we
2034 * have to be pessimistic.
2035 */
2036static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
2037					  struct btrfs_root *root,
2038					  struct btrfs_path *path, int level)
2039{
2040	struct btrfs_fs_info *fs_info = root->fs_info;
2041	struct extent_buffer *right = NULL;
2042	struct extent_buffer *mid;
2043	struct extent_buffer *left = NULL;
2044	struct extent_buffer *parent = NULL;
2045	int ret = 0;
2046	int wret;
2047	int pslot;
2048	int orig_slot = path->slots[level];
2049
2050	if (level == 0)
2051		return 1;
2052
2053	mid = path->nodes[level];
2054	WARN_ON(btrfs_header_generation(mid) != trans->transid);
2055
2056	if (level < BTRFS_MAX_LEVEL - 1) {
2057		parent = path->nodes[level + 1];
2058		pslot = path->slots[level + 1];
2059	}
2060
2061	if (!parent)
2062		return 1;
2063
2064	left = btrfs_read_node_slot(parent, pslot - 1);
2065	if (IS_ERR(left))
2066		left = NULL;
2067
2068	/* first, try to make some room in the middle buffer */
2069	if (left) {
2070		u32 left_nr;
2071
2072		btrfs_tree_lock(left);
2073		btrfs_set_lock_blocking_write(left);
2074
2075		left_nr = btrfs_header_nritems(left);
2076		if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2077			wret = 1;
2078		} else {
2079			ret = btrfs_cow_block(trans, root, left, parent,
2080					      pslot - 1, &left);
2081			if (ret)
2082				wret = 1;
2083			else {
2084				wret = push_node_left(trans, left, mid, 0);
 
2085			}
2086		}
2087		if (wret < 0)
2088			ret = wret;
2089		if (wret == 0) {
2090			struct btrfs_disk_key disk_key;
2091			orig_slot += left_nr;
2092			btrfs_node_key(mid, &disk_key, 0);
2093			ret = tree_mod_log_insert_key(parent, pslot,
2094					MOD_LOG_KEY_REPLACE, GFP_NOFS);
2095			BUG_ON(ret < 0);
2096			btrfs_set_node_key(parent, &disk_key, pslot);
2097			btrfs_mark_buffer_dirty(parent);
2098			if (btrfs_header_nritems(left) > orig_slot) {
2099				path->nodes[level] = left;
2100				path->slots[level + 1] -= 1;
2101				path->slots[level] = orig_slot;
2102				btrfs_tree_unlock(mid);
2103				free_extent_buffer(mid);
2104			} else {
2105				orig_slot -=
2106					btrfs_header_nritems(left);
2107				path->slots[level] = orig_slot;
2108				btrfs_tree_unlock(left);
2109				free_extent_buffer(left);
2110			}
2111			return 0;
2112		}
2113		btrfs_tree_unlock(left);
2114		free_extent_buffer(left);
2115	}
2116	right = btrfs_read_node_slot(parent, pslot + 1);
2117	if (IS_ERR(right))
2118		right = NULL;
2119
2120	/*
2121	 * then try to empty the right most buffer into the middle
2122	 */
2123	if (right) {
2124		u32 right_nr;
2125
2126		btrfs_tree_lock(right);
2127		btrfs_set_lock_blocking_write(right);
2128
2129		right_nr = btrfs_header_nritems(right);
2130		if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2131			wret = 1;
2132		} else {
2133			ret = btrfs_cow_block(trans, root, right,
2134					      parent, pslot + 1,
2135					      &right);
2136			if (ret)
2137				wret = 1;
2138			else {
2139				wret = balance_node_right(trans, right, mid);
 
2140			}
2141		}
2142		if (wret < 0)
2143			ret = wret;
2144		if (wret == 0) {
2145			struct btrfs_disk_key disk_key;
2146
2147			btrfs_node_key(right, &disk_key, 0);
2148			ret = tree_mod_log_insert_key(parent, pslot + 1,
2149					MOD_LOG_KEY_REPLACE, GFP_NOFS);
2150			BUG_ON(ret < 0);
2151			btrfs_set_node_key(parent, &disk_key, pslot + 1);
2152			btrfs_mark_buffer_dirty(parent);
2153
2154			if (btrfs_header_nritems(mid) <= orig_slot) {
2155				path->nodes[level] = right;
2156				path->slots[level + 1] += 1;
2157				path->slots[level] = orig_slot -
2158					btrfs_header_nritems(mid);
2159				btrfs_tree_unlock(mid);
2160				free_extent_buffer(mid);
2161			} else {
2162				btrfs_tree_unlock(right);
2163				free_extent_buffer(right);
2164			}
2165			return 0;
2166		}
2167		btrfs_tree_unlock(right);
2168		free_extent_buffer(right);
2169	}
2170	return 1;
2171}
2172
2173/*
2174 * readahead one full node of leaves, finding things that are close
2175 * to the block in 'slot', and triggering ra on them.
2176 */
2177static void reada_for_search(struct btrfs_fs_info *fs_info,
2178			     struct btrfs_path *path,
2179			     int level, int slot, u64 objectid)
2180{
2181	struct extent_buffer *node;
2182	struct btrfs_disk_key disk_key;
2183	u32 nritems;
2184	u64 search;
2185	u64 target;
2186	u64 nread = 0;
 
2187	struct extent_buffer *eb;
2188	u32 nr;
2189	u32 blocksize;
2190	u32 nscan = 0;
2191
2192	if (level != 1)
2193		return;
2194
2195	if (!path->nodes[level])
2196		return;
2197
2198	node = path->nodes[level];
2199
2200	search = btrfs_node_blockptr(node, slot);
2201	blocksize = fs_info->nodesize;
2202	eb = find_extent_buffer(fs_info, search);
2203	if (eb) {
2204		free_extent_buffer(eb);
2205		return;
2206	}
2207
2208	target = search;
2209
2210	nritems = btrfs_header_nritems(node);
2211	nr = slot;
2212
2213	while (1) {
2214		if (path->reada == READA_BACK) {
2215			if (nr == 0)
2216				break;
2217			nr--;
2218		} else if (path->reada == READA_FORWARD) {
2219			nr++;
2220			if (nr >= nritems)
2221				break;
2222		}
2223		if (path->reada == READA_BACK && objectid) {
2224			btrfs_node_key(node, &disk_key, nr);
2225			if (btrfs_disk_key_objectid(&disk_key) != objectid)
2226				break;
2227		}
2228		search = btrfs_node_blockptr(node, nr);
2229		if ((search <= target && target - search <= 65536) ||
2230		    (search > target && search - target <= 65536)) {
2231			readahead_tree_block(fs_info, search);
 
2232			nread += blocksize;
2233		}
2234		nscan++;
2235		if ((nread > 65536 || nscan > 32))
2236			break;
2237	}
2238}
2239
2240static noinline void reada_for_balance(struct btrfs_fs_info *fs_info,
2241				       struct btrfs_path *path, int level)
2242{
2243	int slot;
2244	int nritems;
2245	struct extent_buffer *parent;
2246	struct extent_buffer *eb;
2247	u64 gen;
2248	u64 block1 = 0;
2249	u64 block2 = 0;
2250
2251	parent = path->nodes[level + 1];
2252	if (!parent)
2253		return;
2254
2255	nritems = btrfs_header_nritems(parent);
2256	slot = path->slots[level + 1];
2257
2258	if (slot > 0) {
2259		block1 = btrfs_node_blockptr(parent, slot - 1);
2260		gen = btrfs_node_ptr_generation(parent, slot - 1);
2261		eb = find_extent_buffer(fs_info, block1);
2262		/*
2263		 * if we get -eagain from btrfs_buffer_uptodate, we
2264		 * don't want to return eagain here.  That will loop
2265		 * forever
2266		 */
2267		if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2268			block1 = 0;
2269		free_extent_buffer(eb);
2270	}
2271	if (slot + 1 < nritems) {
2272		block2 = btrfs_node_blockptr(parent, slot + 1);
2273		gen = btrfs_node_ptr_generation(parent, slot + 1);
2274		eb = find_extent_buffer(fs_info, block2);
2275		if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2276			block2 = 0;
2277		free_extent_buffer(eb);
2278	}
2279
2280	if (block1)
2281		readahead_tree_block(fs_info, block1);
2282	if (block2)
2283		readahead_tree_block(fs_info, block2);
2284}
2285
2286
2287/*
2288 * when we walk down the tree, it is usually safe to unlock the higher layers
2289 * in the tree.  The exceptions are when our path goes through slot 0, because
2290 * operations on the tree might require changing key pointers higher up in the
2291 * tree.
2292 *
2293 * callers might also have set path->keep_locks, which tells this code to keep
2294 * the lock if the path points to the last slot in the block.  This is part of
2295 * walking through the tree, and selecting the next slot in the higher block.
2296 *
2297 * lowest_unlock sets the lowest level in the tree we're allowed to unlock.  so
2298 * if lowest_unlock is 1, level 0 won't be unlocked
2299 */
2300static noinline void unlock_up(struct btrfs_path *path, int level,
2301			       int lowest_unlock, int min_write_lock_level,
2302			       int *write_lock_level)
2303{
2304	int i;
2305	int skip_level = level;
2306	int no_skips = 0;
2307	struct extent_buffer *t;
2308
2309	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2310		if (!path->nodes[i])
2311			break;
2312		if (!path->locks[i])
2313			break;
2314		if (!no_skips && path->slots[i] == 0) {
2315			skip_level = i + 1;
2316			continue;
2317		}
2318		if (!no_skips && path->keep_locks) {
2319			u32 nritems;
2320			t = path->nodes[i];
2321			nritems = btrfs_header_nritems(t);
2322			if (nritems < 1 || path->slots[i] >= nritems - 1) {
2323				skip_level = i + 1;
2324				continue;
2325			}
2326		}
2327		if (skip_level < i && i >= lowest_unlock)
2328			no_skips = 1;
2329
2330		t = path->nodes[i];
2331		if (i >= lowest_unlock && i > skip_level) {
2332			btrfs_tree_unlock_rw(t, path->locks[i]);
2333			path->locks[i] = 0;
2334			if (write_lock_level &&
2335			    i > min_write_lock_level &&
2336			    i <= *write_lock_level) {
2337				*write_lock_level = i - 1;
2338			}
2339		}
2340	}
2341}
2342
2343/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2344 * helper function for btrfs_search_slot.  The goal is to find a block
2345 * in cache without setting the path to blocking.  If we find the block
2346 * we return zero and the path is unchanged.
2347 *
2348 * If we can't find the block, we set the path blocking and do some
2349 * reada.  -EAGAIN is returned and the search must be repeated.
2350 */
2351static int
2352read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
2353		      struct extent_buffer **eb_ret, int level, int slot,
2354		      const struct btrfs_key *key)
 
2355{
2356	struct btrfs_fs_info *fs_info = root->fs_info;
2357	u64 blocknr;
2358	u64 gen;
 
2359	struct extent_buffer *tmp;
2360	struct btrfs_key first_key;
2361	int ret;
2362	int parent_level;
2363
2364	blocknr = btrfs_node_blockptr(*eb_ret, slot);
2365	gen = btrfs_node_ptr_generation(*eb_ret, slot);
2366	parent_level = btrfs_header_level(*eb_ret);
2367	btrfs_node_key_to_cpu(*eb_ret, &first_key, slot);
2368
2369	tmp = find_extent_buffer(fs_info, blocknr);
2370	if (tmp) {
2371		/* first we do an atomic uptodate check */
2372		if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2373			/*
2374			 * Do extra check for first_key, eb can be stale due to
2375			 * being cached, read from scrub, or have multiple
2376			 * parents (shared tree blocks).
2377			 */
2378			if (btrfs_verify_level_key(tmp,
2379					parent_level - 1, &first_key, gen)) {
2380				free_extent_buffer(tmp);
2381				return -EUCLEAN;
2382			}
2383			*eb_ret = tmp;
2384			return 0;
2385		}
2386
2387		/* the pages were up to date, but we failed
2388		 * the generation number check.  Do a full
2389		 * read for the generation number that is correct.
2390		 * We must do this without dropping locks so
2391		 * we can trust our generation number
2392		 */
2393		btrfs_set_path_blocking(p);
2394
2395		/* now we're allowed to do a blocking uptodate check */
2396		ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
2397		if (!ret) {
2398			*eb_ret = tmp;
2399			return 0;
2400		}
2401		free_extent_buffer(tmp);
2402		btrfs_release_path(p);
2403		return -EIO;
2404	}
2405
2406	/*
2407	 * reduce lock contention at high levels
2408	 * of the btree by dropping locks before
2409	 * we read.  Don't release the lock on the current
2410	 * level because we need to walk this node to figure
2411	 * out which blocks to read.
2412	 */
2413	btrfs_unlock_up_safe(p, level + 1);
2414	btrfs_set_path_blocking(p);
2415
 
2416	if (p->reada != READA_NONE)
2417		reada_for_search(fs_info, p, level, slot, key->objectid);
 
 
2418
2419	ret = -EAGAIN;
2420	tmp = read_tree_block(fs_info, blocknr, gen, parent_level - 1,
2421			      &first_key);
2422	if (!IS_ERR(tmp)) {
2423		/*
2424		 * If the read above didn't mark this buffer up to date,
2425		 * it will never end up being up to date.  Set ret to EIO now
2426		 * and give up so that our caller doesn't loop forever
2427		 * on our EAGAINs.
2428		 */
2429		if (!extent_buffer_uptodate(tmp))
2430			ret = -EIO;
2431		free_extent_buffer(tmp);
2432	} else {
2433		ret = PTR_ERR(tmp);
2434	}
2435
2436	btrfs_release_path(p);
2437	return ret;
2438}
2439
2440/*
2441 * helper function for btrfs_search_slot.  This does all of the checks
2442 * for node-level blocks and does any balancing required based on
2443 * the ins_len.
2444 *
2445 * If no extra work was required, zero is returned.  If we had to
2446 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2447 * start over
2448 */
2449static int
2450setup_nodes_for_search(struct btrfs_trans_handle *trans,
2451		       struct btrfs_root *root, struct btrfs_path *p,
2452		       struct extent_buffer *b, int level, int ins_len,
2453		       int *write_lock_level)
2454{
2455	struct btrfs_fs_info *fs_info = root->fs_info;
2456	int ret;
2457
2458	if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2459	    BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
2460		int sret;
2461
2462		if (*write_lock_level < level + 1) {
2463			*write_lock_level = level + 1;
2464			btrfs_release_path(p);
2465			goto again;
2466		}
2467
2468		btrfs_set_path_blocking(p);
2469		reada_for_balance(fs_info, p, level);
2470		sret = split_node(trans, root, p, level);
 
2471
2472		BUG_ON(sret > 0);
2473		if (sret) {
2474			ret = sret;
2475			goto done;
2476		}
2477		b = p->nodes[level];
2478	} else if (ins_len < 0 && btrfs_header_nritems(b) <
2479		   BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
2480		int sret;
2481
2482		if (*write_lock_level < level + 1) {
2483			*write_lock_level = level + 1;
2484			btrfs_release_path(p);
2485			goto again;
2486		}
2487
2488		btrfs_set_path_blocking(p);
2489		reada_for_balance(fs_info, p, level);
2490		sret = balance_level(trans, root, p, level);
 
2491
2492		if (sret) {
2493			ret = sret;
2494			goto done;
2495		}
2496		b = p->nodes[level];
2497		if (!b) {
2498			btrfs_release_path(p);
2499			goto again;
2500		}
2501		BUG_ON(btrfs_header_nritems(b) == 1);
2502	}
2503	return 0;
2504
2505again:
2506	ret = -EAGAIN;
2507done:
2508	return ret;
2509}
2510
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2511int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
2512		u64 iobjectid, u64 ioff, u8 key_type,
2513		struct btrfs_key *found_key)
2514{
2515	int ret;
2516	struct btrfs_key key;
2517	struct extent_buffer *eb;
2518
2519	ASSERT(path);
2520	ASSERT(found_key);
2521
2522	key.type = key_type;
2523	key.objectid = iobjectid;
2524	key.offset = ioff;
2525
2526	ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
2527	if (ret < 0)
2528		return ret;
2529
2530	eb = path->nodes[0];
2531	if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
2532		ret = btrfs_next_leaf(fs_root, path);
2533		if (ret)
2534			return ret;
2535		eb = path->nodes[0];
2536	}
2537
2538	btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
2539	if (found_key->type != key.type ||
2540			found_key->objectid != key.objectid)
2541		return 1;
2542
2543	return 0;
2544}
2545
2546static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
2547							struct btrfs_path *p,
2548							int write_lock_level)
2549{
2550	struct btrfs_fs_info *fs_info = root->fs_info;
2551	struct extent_buffer *b;
2552	int root_lock;
2553	int level = 0;
2554
2555	/* We try very hard to do read locks on the root */
2556	root_lock = BTRFS_READ_LOCK;
2557
2558	if (p->search_commit_root) {
2559		/*
2560		 * The commit roots are read only so we always do read locks,
2561		 * and we always must hold the commit_root_sem when doing
2562		 * searches on them, the only exception is send where we don't
2563		 * want to block transaction commits for a long time, so
2564		 * we need to clone the commit root in order to avoid races
2565		 * with transaction commits that create a snapshot of one of
2566		 * the roots used by a send operation.
2567		 */
2568		if (p->need_commit_sem) {
2569			down_read(&fs_info->commit_root_sem);
2570			b = btrfs_clone_extent_buffer(root->commit_root);
2571			up_read(&fs_info->commit_root_sem);
2572			if (!b)
2573				return ERR_PTR(-ENOMEM);
2574
2575		} else {
2576			b = root->commit_root;
2577			atomic_inc(&b->refs);
2578		}
2579		level = btrfs_header_level(b);
2580		/*
2581		 * Ensure that all callers have set skip_locking when
2582		 * p->search_commit_root = 1.
2583		 */
2584		ASSERT(p->skip_locking == 1);
2585
2586		goto out;
2587	}
2588
2589	if (p->skip_locking) {
2590		b = btrfs_root_node(root);
2591		level = btrfs_header_level(b);
2592		goto out;
2593	}
2594
2595	/*
2596	 * If the level is set to maximum, we can skip trying to get the read
2597	 * lock.
2598	 */
2599	if (write_lock_level < BTRFS_MAX_LEVEL) {
2600		/*
2601		 * We don't know the level of the root node until we actually
2602		 * have it read locked
2603		 */
2604		b = btrfs_read_lock_root_node(root);
2605		level = btrfs_header_level(b);
2606		if (level > write_lock_level)
2607			goto out;
2608
2609		/* Whoops, must trade for write lock */
2610		btrfs_tree_read_unlock(b);
2611		free_extent_buffer(b);
2612	}
2613
2614	b = btrfs_lock_root_node(root);
2615	root_lock = BTRFS_WRITE_LOCK;
2616
2617	/* The level might have changed, check again */
2618	level = btrfs_header_level(b);
2619
2620out:
2621	p->nodes[level] = b;
2622	if (!p->skip_locking)
2623		p->locks[level] = root_lock;
2624	/*
2625	 * Callers are responsible for dropping b's references.
2626	 */
2627	return b;
2628}
2629
2630
2631/*
2632 * btrfs_search_slot - look for a key in a tree and perform necessary
2633 * modifications to preserve tree invariants.
2634 *
2635 * @trans:	Handle of transaction, used when modifying the tree
2636 * @p:		Holds all btree nodes along the search path
2637 * @root:	The root node of the tree
2638 * @key:	The key we are looking for
2639 * @ins_len:	Indicates purpose of search, for inserts it is 1, for
2640 *		deletions it's -1. 0 for plain searches
2641 * @cow:	boolean should CoW operations be performed. Must always be 1
2642 *		when modifying the tree.
2643 *
2644 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2645 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2646 *
2647 * If @key is found, 0 is returned and you can find the item in the leaf level
2648 * of the path (level 0)
2649 *
2650 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2651 * points to the slot where it should be inserted
2652 *
2653 * If an error is encountered while searching the tree a negative error number
2654 * is returned
2655 */
2656int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2657		      const struct btrfs_key *key, struct btrfs_path *p,
2658		      int ins_len, int cow)
2659{
2660	struct extent_buffer *b;
2661	int slot;
2662	int ret;
2663	int err;
2664	int level;
2665	int lowest_unlock = 1;
 
2666	/* everything at write_lock_level or lower must be write locked */
2667	int write_lock_level = 0;
2668	u8 lowest_level = 0;
2669	int min_write_lock_level;
2670	int prev_cmp;
2671
2672	lowest_level = p->lowest_level;
2673	WARN_ON(lowest_level && ins_len > 0);
2674	WARN_ON(p->nodes[0] != NULL);
2675	BUG_ON(!cow && ins_len);
2676
2677	if (ins_len < 0) {
2678		lowest_unlock = 2;
2679
2680		/* when we are removing items, we might have to go up to level
2681		 * two as we update tree pointers  Make sure we keep write
2682		 * for those levels as well
2683		 */
2684		write_lock_level = 2;
2685	} else if (ins_len > 0) {
2686		/*
2687		 * for inserting items, make sure we have a write lock on
2688		 * level 1 so we can update keys
2689		 */
2690		write_lock_level = 1;
2691	}
2692
2693	if (!cow)
2694		write_lock_level = -1;
2695
2696	if (cow && (p->keep_locks || p->lowest_level))
2697		write_lock_level = BTRFS_MAX_LEVEL;
2698
2699	min_write_lock_level = write_lock_level;
2700
2701again:
2702	prev_cmp = -1;
2703	b = btrfs_search_slot_get_root(root, p, write_lock_level);
2704	if (IS_ERR(b)) {
2705		ret = PTR_ERR(b);
2706		goto done;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2707	}
 
 
 
2708
2709	while (b) {
2710		int dec = 0;
2711
2712		level = btrfs_header_level(b);
2713
 
 
 
 
2714		if (cow) {
2715			bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2716
2717			/*
2718			 * if we don't really need to cow this block
2719			 * then we don't want to set the path blocking,
2720			 * so we test it here
2721			 */
2722			if (!should_cow_block(trans, root, b)) {
2723				trans->dirty = true;
2724				goto cow_done;
2725			}
2726
2727			/*
2728			 * must have write locks on this node and the
2729			 * parent
2730			 */
2731			if (level > write_lock_level ||
2732			    (level + 1 > write_lock_level &&
2733			    level + 1 < BTRFS_MAX_LEVEL &&
2734			    p->nodes[level + 1])) {
2735				write_lock_level = level + 1;
2736				btrfs_release_path(p);
2737				goto again;
2738			}
2739
2740			btrfs_set_path_blocking(p);
2741			if (last_level)
2742				err = btrfs_cow_block(trans, root, b, NULL, 0,
2743						      &b);
2744			else
2745				err = btrfs_cow_block(trans, root, b,
2746						      p->nodes[level + 1],
2747						      p->slots[level + 1], &b);
2748			if (err) {
2749				ret = err;
2750				goto done;
2751			}
2752		}
2753cow_done:
2754		p->nodes[level] = b;
2755		/*
2756		 * Leave path with blocking locks to avoid massive
2757		 * lock context switch, this is made on purpose.
2758		 */
2759
2760		/*
2761		 * we have a lock on b and as long as we aren't changing
2762		 * the tree, there is no way to for the items in b to change.
2763		 * It is safe to drop the lock on our parent before we
2764		 * go through the expensive btree search on b.
2765		 *
2766		 * If we're inserting or deleting (ins_len != 0), then we might
2767		 * be changing slot zero, which may require changing the parent.
2768		 * So, we can't drop the lock until after we know which slot
2769		 * we're operating on.
2770		 */
2771		if (!ins_len && !p->keep_locks) {
2772			int u = level + 1;
2773
2774			if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2775				btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2776				p->locks[u] = 0;
2777			}
2778		}
2779
2780		/*
2781		 * If btrfs_bin_search returns an exact match (prev_cmp == 0)
2782		 * we can safely assume the target key will always be in slot 0
2783		 * on lower levels due to the invariants BTRFS' btree provides,
2784		 * namely that a btrfs_key_ptr entry always points to the
2785		 * lowest key in the child node, thus we can skip searching
2786		 * lower levels
2787		 */
2788		if (prev_cmp == 0) {
2789			slot = 0;
2790			ret = 0;
2791		} else {
2792			ret = btrfs_bin_search(b, key, &slot);
2793			prev_cmp = ret;
2794			if (ret < 0)
2795				goto done;
2796		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2797
2798		if (level == 0) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2799			p->slots[level] = slot;
2800			if (ins_len > 0 &&
2801			    btrfs_leaf_free_space(b) < ins_len) {
2802				if (write_lock_level < 1) {
2803					write_lock_level = 1;
2804					btrfs_release_path(p);
2805					goto again;
2806				}
2807
2808				btrfs_set_path_blocking(p);
2809				err = split_leaf(trans, root, key,
2810						 p, ins_len, ret == 0);
 
2811
2812				BUG_ON(err > 0);
2813				if (err) {
2814					ret = err;
2815					goto done;
2816				}
2817			}
2818			if (!p->search_for_split)
2819				unlock_up(p, level, lowest_unlock,
2820					  min_write_lock_level, NULL);
2821			goto done;
2822		}
2823		if (ret && slot > 0) {
2824			dec = 1;
2825			slot--;
2826		}
2827		p->slots[level] = slot;
2828		err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
2829					     &write_lock_level);
2830		if (err == -EAGAIN)
2831			goto again;
2832		if (err) {
2833			ret = err;
2834			goto done;
2835		}
2836		b = p->nodes[level];
2837		slot = p->slots[level];
2838
2839		/*
2840		 * Slot 0 is special, if we change the key we have to update
2841		 * the parent pointer which means we must have a write lock on
2842		 * the parent
2843		 */
2844		if (slot == 0 && ins_len && write_lock_level < level + 1) {
2845			write_lock_level = level + 1;
2846			btrfs_release_path(p);
2847			goto again;
2848		}
2849
2850		unlock_up(p, level, lowest_unlock, min_write_lock_level,
2851			  &write_lock_level);
2852
2853		if (level == lowest_level) {
2854			if (dec)
2855				p->slots[level]++;
2856			goto done;
2857		}
2858
2859		err = read_block_for_search(root, p, &b, level, slot, key);
2860		if (err == -EAGAIN)
2861			goto again;
2862		if (err) {
2863			ret = err;
2864			goto done;
2865		}
2866
2867		if (!p->skip_locking) {
2868			level = btrfs_header_level(b);
2869			if (level <= write_lock_level) {
2870				if (!btrfs_try_tree_write_lock(b)) {
2871					btrfs_set_path_blocking(p);
2872					btrfs_tree_lock(b);
2873				}
2874				p->locks[level] = BTRFS_WRITE_LOCK;
2875			} else {
2876				if (!btrfs_tree_read_lock_atomic(b)) {
2877					btrfs_set_path_blocking(p);
2878					btrfs_tree_read_lock(b);
2879				}
2880				p->locks[level] = BTRFS_READ_LOCK;
2881			}
2882			p->nodes[level] = b;
2883		}
2884	}
2885	ret = 1;
2886done:
2887	/*
2888	 * we don't really know what they plan on doing with the path
2889	 * from here on, so for now just mark it as blocking
2890	 */
2891	if (!p->leave_spinning)
2892		btrfs_set_path_blocking(p);
2893	if (ret < 0 && !p->skip_release_on_error)
2894		btrfs_release_path(p);
2895	return ret;
2896}
2897
2898/*
2899 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2900 * current state of the tree together with the operations recorded in the tree
2901 * modification log to search for the key in a previous version of this tree, as
2902 * denoted by the time_seq parameter.
2903 *
2904 * Naturally, there is no support for insert, delete or cow operations.
2905 *
2906 * The resulting path and return value will be set up as if we called
2907 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2908 */
2909int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2910			  struct btrfs_path *p, u64 time_seq)
2911{
2912	struct btrfs_fs_info *fs_info = root->fs_info;
2913	struct extent_buffer *b;
2914	int slot;
2915	int ret;
2916	int err;
2917	int level;
2918	int lowest_unlock = 1;
2919	u8 lowest_level = 0;
 
2920
2921	lowest_level = p->lowest_level;
2922	WARN_ON(p->nodes[0] != NULL);
2923
2924	if (p->search_commit_root) {
2925		BUG_ON(time_seq);
2926		return btrfs_search_slot(NULL, root, key, p, 0, 0);
2927	}
2928
2929again:
2930	b = get_old_root(root, time_seq);
2931	if (!b) {
2932		ret = -EIO;
2933		goto done;
2934	}
2935	level = btrfs_header_level(b);
2936	p->locks[level] = BTRFS_READ_LOCK;
2937
2938	while (b) {
2939		int dec = 0;
2940
2941		level = btrfs_header_level(b);
2942		p->nodes[level] = b;
 
2943
2944		/*
2945		 * we have a lock on b and as long as we aren't changing
2946		 * the tree, there is no way to for the items in b to change.
2947		 * It is safe to drop the lock on our parent before we
2948		 * go through the expensive btree search on b.
2949		 */
2950		btrfs_unlock_up_safe(p, level + 1);
2951
2952		ret = btrfs_bin_search(b, key, &slot);
2953		if (ret < 0)
2954			goto done;
 
 
 
2955
2956		if (level == 0) {
 
 
 
 
 
2957			p->slots[level] = slot;
2958			unlock_up(p, level, lowest_unlock, 0, NULL);
2959			goto done;
2960		}
2961
2962		if (ret && slot > 0) {
2963			dec = 1;
2964			slot--;
2965		}
2966		p->slots[level] = slot;
2967		unlock_up(p, level, lowest_unlock, 0, NULL);
2968
2969		if (level == lowest_level) {
2970			if (dec)
2971				p->slots[level]++;
2972			goto done;
2973		}
2974
2975		err = read_block_for_search(root, p, &b, level, slot, key);
2976		if (err == -EAGAIN)
2977			goto again;
2978		if (err) {
2979			ret = err;
2980			goto done;
2981		}
 
2982
2983		level = btrfs_header_level(b);
2984		if (!btrfs_tree_read_lock_atomic(b)) {
2985			btrfs_set_path_blocking(p);
2986			btrfs_tree_read_lock(b);
2987		}
2988		b = tree_mod_log_rewind(fs_info, p, b, time_seq);
2989		if (!b) {
2990			ret = -ENOMEM;
 
 
 
 
 
 
 
 
 
 
2991			goto done;
2992		}
2993		p->locks[level] = BTRFS_READ_LOCK;
2994		p->nodes[level] = b;
2995	}
2996	ret = 1;
2997done:
2998	if (!p->leave_spinning)
2999		btrfs_set_path_blocking(p);
3000	if (ret < 0)
3001		btrfs_release_path(p);
3002
3003	return ret;
3004}
3005
3006/*
3007 * helper to use instead of search slot if no exact match is needed but
3008 * instead the next or previous item should be returned.
3009 * When find_higher is true, the next higher item is returned, the next lower
3010 * otherwise.
3011 * When return_any and find_higher are both true, and no higher item is found,
3012 * return the next lower instead.
3013 * When return_any is true and find_higher is false, and no lower item is found,
3014 * return the next higher instead.
3015 * It returns 0 if any item is found, 1 if none is found (tree empty), and
3016 * < 0 on error
3017 */
3018int btrfs_search_slot_for_read(struct btrfs_root *root,
3019			       const struct btrfs_key *key,
3020			       struct btrfs_path *p, int find_higher,
3021			       int return_any)
3022{
3023	int ret;
3024	struct extent_buffer *leaf;
3025
3026again:
3027	ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
3028	if (ret <= 0)
3029		return ret;
3030	/*
3031	 * a return value of 1 means the path is at the position where the
3032	 * item should be inserted. Normally this is the next bigger item,
3033	 * but in case the previous item is the last in a leaf, path points
3034	 * to the first free slot in the previous leaf, i.e. at an invalid
3035	 * item.
3036	 */
3037	leaf = p->nodes[0];
3038
3039	if (find_higher) {
3040		if (p->slots[0] >= btrfs_header_nritems(leaf)) {
3041			ret = btrfs_next_leaf(root, p);
3042			if (ret <= 0)
3043				return ret;
3044			if (!return_any)
3045				return 1;
3046			/*
3047			 * no higher item found, return the next
3048			 * lower instead
3049			 */
3050			return_any = 0;
3051			find_higher = 0;
3052			btrfs_release_path(p);
3053			goto again;
3054		}
3055	} else {
3056		if (p->slots[0] == 0) {
3057			ret = btrfs_prev_leaf(root, p);
3058			if (ret < 0)
3059				return ret;
3060			if (!ret) {
3061				leaf = p->nodes[0];
3062				if (p->slots[0] == btrfs_header_nritems(leaf))
3063					p->slots[0]--;
3064				return 0;
3065			}
3066			if (!return_any)
3067				return 1;
3068			/*
3069			 * no lower item found, return the next
3070			 * higher instead
3071			 */
3072			return_any = 0;
3073			find_higher = 1;
3074			btrfs_release_path(p);
3075			goto again;
3076		} else {
3077			--p->slots[0];
3078		}
3079	}
3080	return 0;
3081}
3082
3083/*
3084 * adjust the pointers going up the tree, starting at level
3085 * making sure the right key of each node is points to 'key'.
3086 * This is used after shifting pointers to the left, so it stops
3087 * fixing up pointers when a given leaf/node is not in slot 0 of the
3088 * higher levels
3089 *
3090 */
3091static void fixup_low_keys(struct btrfs_path *path,
 
3092			   struct btrfs_disk_key *key, int level)
3093{
3094	int i;
3095	struct extent_buffer *t;
3096	int ret;
3097
3098	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
3099		int tslot = path->slots[i];
3100
3101		if (!path->nodes[i])
3102			break;
3103		t = path->nodes[i];
3104		ret = tree_mod_log_insert_key(t, tslot, MOD_LOG_KEY_REPLACE,
3105				GFP_ATOMIC);
3106		BUG_ON(ret < 0);
3107		btrfs_set_node_key(t, key, tslot);
3108		btrfs_mark_buffer_dirty(path->nodes[i]);
3109		if (tslot != 0)
3110			break;
3111	}
3112}
3113
3114/*
3115 * update item key.
3116 *
3117 * This function isn't completely safe. It's the caller's responsibility
3118 * that the new key won't break the order
3119 */
3120void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
3121			     struct btrfs_path *path,
3122			     const struct btrfs_key *new_key)
3123{
3124	struct btrfs_disk_key disk_key;
3125	struct extent_buffer *eb;
3126	int slot;
3127
3128	eb = path->nodes[0];
3129	slot = path->slots[0];
3130	if (slot > 0) {
3131		btrfs_item_key(eb, &disk_key, slot - 1);
3132		if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
3133			btrfs_crit(fs_info,
3134		"slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3135				   slot, btrfs_disk_key_objectid(&disk_key),
3136				   btrfs_disk_key_type(&disk_key),
3137				   btrfs_disk_key_offset(&disk_key),
3138				   new_key->objectid, new_key->type,
3139				   new_key->offset);
3140			btrfs_print_leaf(eb);
3141			BUG();
3142		}
3143	}
3144	if (slot < btrfs_header_nritems(eb) - 1) {
3145		btrfs_item_key(eb, &disk_key, slot + 1);
3146		if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
3147			btrfs_crit(fs_info,
3148		"slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3149				   slot, btrfs_disk_key_objectid(&disk_key),
3150				   btrfs_disk_key_type(&disk_key),
3151				   btrfs_disk_key_offset(&disk_key),
3152				   new_key->objectid, new_key->type,
3153				   new_key->offset);
3154			btrfs_print_leaf(eb);
3155			BUG();
3156		}
3157	}
3158
3159	btrfs_cpu_key_to_disk(&disk_key, new_key);
3160	btrfs_set_item_key(eb, &disk_key, slot);
3161	btrfs_mark_buffer_dirty(eb);
3162	if (slot == 0)
3163		fixup_low_keys(path, &disk_key, 1);
3164}
3165
3166/*
3167 * try to push data from one node into the next node left in the
3168 * tree.
3169 *
3170 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
3171 * error, and > 0 if there was no room in the left hand block.
3172 */
3173static int push_node_left(struct btrfs_trans_handle *trans,
3174			  struct extent_buffer *dst,
3175			  struct extent_buffer *src, int empty)
3176{
3177	struct btrfs_fs_info *fs_info = trans->fs_info;
3178	int push_items = 0;
3179	int src_nritems;
3180	int dst_nritems;
3181	int ret = 0;
3182
3183	src_nritems = btrfs_header_nritems(src);
3184	dst_nritems = btrfs_header_nritems(dst);
3185	push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3186	WARN_ON(btrfs_header_generation(src) != trans->transid);
3187	WARN_ON(btrfs_header_generation(dst) != trans->transid);
3188
3189	if (!empty && src_nritems <= 8)
3190		return 1;
3191
3192	if (push_items <= 0)
3193		return 1;
3194
3195	if (empty) {
3196		push_items = min(src_nritems, push_items);
3197		if (push_items < src_nritems) {
3198			/* leave at least 8 pointers in the node if
3199			 * we aren't going to empty it
3200			 */
3201			if (src_nritems - push_items < 8) {
3202				if (push_items <= 8)
3203					return 1;
3204				push_items -= 8;
3205			}
3206		}
3207	} else
3208		push_items = min(src_nritems - 8, push_items);
3209
3210	ret = tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
 
3211	if (ret) {
3212		btrfs_abort_transaction(trans, ret);
3213		return ret;
3214	}
3215	copy_extent_buffer(dst, src,
3216			   btrfs_node_key_ptr_offset(dst_nritems),
3217			   btrfs_node_key_ptr_offset(0),
3218			   push_items * sizeof(struct btrfs_key_ptr));
3219
3220	if (push_items < src_nritems) {
3221		/*
3222		 * Don't call tree_mod_log_insert_move here, key removal was
3223		 * already fully logged by tree_mod_log_eb_copy above.
3224		 */
3225		memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3226				      btrfs_node_key_ptr_offset(push_items),
3227				      (src_nritems - push_items) *
3228				      sizeof(struct btrfs_key_ptr));
3229	}
3230	btrfs_set_header_nritems(src, src_nritems - push_items);
3231	btrfs_set_header_nritems(dst, dst_nritems + push_items);
3232	btrfs_mark_buffer_dirty(src);
3233	btrfs_mark_buffer_dirty(dst);
3234
3235	return ret;
3236}
3237
3238/*
3239 * try to push data from one node into the next node right in the
3240 * tree.
3241 *
3242 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3243 * error, and > 0 if there was no room in the right hand block.
3244 *
3245 * this will  only push up to 1/2 the contents of the left node over
3246 */
3247static int balance_node_right(struct btrfs_trans_handle *trans,
 
3248			      struct extent_buffer *dst,
3249			      struct extent_buffer *src)
3250{
3251	struct btrfs_fs_info *fs_info = trans->fs_info;
3252	int push_items = 0;
3253	int max_push;
3254	int src_nritems;
3255	int dst_nritems;
3256	int ret = 0;
3257
3258	WARN_ON(btrfs_header_generation(src) != trans->transid);
3259	WARN_ON(btrfs_header_generation(dst) != trans->transid);
3260
3261	src_nritems = btrfs_header_nritems(src);
3262	dst_nritems = btrfs_header_nritems(dst);
3263	push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3264	if (push_items <= 0)
3265		return 1;
3266
3267	if (src_nritems < 4)
3268		return 1;
3269
3270	max_push = src_nritems / 2 + 1;
3271	/* don't try to empty the node */
3272	if (max_push >= src_nritems)
3273		return 1;
3274
3275	if (max_push < push_items)
3276		push_items = max_push;
3277
3278	ret = tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
3279	BUG_ON(ret < 0);
3280	memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3281				      btrfs_node_key_ptr_offset(0),
3282				      (dst_nritems) *
3283				      sizeof(struct btrfs_key_ptr));
3284
3285	ret = tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
3286				   push_items);
3287	if (ret) {
3288		btrfs_abort_transaction(trans, ret);
3289		return ret;
3290	}
3291	copy_extent_buffer(dst, src,
3292			   btrfs_node_key_ptr_offset(0),
3293			   btrfs_node_key_ptr_offset(src_nritems - push_items),
3294			   push_items * sizeof(struct btrfs_key_ptr));
3295
3296	btrfs_set_header_nritems(src, src_nritems - push_items);
3297	btrfs_set_header_nritems(dst, dst_nritems + push_items);
3298
3299	btrfs_mark_buffer_dirty(src);
3300	btrfs_mark_buffer_dirty(dst);
3301
3302	return ret;
3303}
3304
3305/*
3306 * helper function to insert a new root level in the tree.
3307 * A new node is allocated, and a single item is inserted to
3308 * point to the existing root
3309 *
3310 * returns zero on success or < 0 on failure.
3311 */
3312static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3313			   struct btrfs_root *root,
3314			   struct btrfs_path *path, int level)
3315{
3316	struct btrfs_fs_info *fs_info = root->fs_info;
3317	u64 lower_gen;
3318	struct extent_buffer *lower;
3319	struct extent_buffer *c;
3320	struct extent_buffer *old;
3321	struct btrfs_disk_key lower_key;
3322	int ret;
3323
3324	BUG_ON(path->nodes[level]);
3325	BUG_ON(path->nodes[level-1] != root->node);
3326
3327	lower = path->nodes[level-1];
3328	if (level == 1)
3329		btrfs_item_key(lower, &lower_key, 0);
3330	else
3331		btrfs_node_key(lower, &lower_key, 0);
3332
3333	c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
3334					 root->node->start, 0);
3335	if (IS_ERR(c))
3336		return PTR_ERR(c);
3337
3338	root_add_used(root, fs_info->nodesize);
3339
 
3340	btrfs_set_header_nritems(c, 1);
 
 
 
 
 
 
 
 
 
 
 
 
3341	btrfs_set_node_key(c, &lower_key, 0);
3342	btrfs_set_node_blockptr(c, 0, lower->start);
3343	lower_gen = btrfs_header_generation(lower);
3344	WARN_ON(lower_gen != trans->transid);
3345
3346	btrfs_set_node_ptr_generation(c, 0, lower_gen);
3347
3348	btrfs_mark_buffer_dirty(c);
3349
3350	old = root->node;
3351	ret = tree_mod_log_insert_root(root->node, c, 0);
3352	BUG_ON(ret < 0);
3353	rcu_assign_pointer(root->node, c);
3354
3355	/* the super has an extra ref to root->node */
3356	free_extent_buffer(old);
3357
3358	add_root_to_dirty_list(root);
3359	atomic_inc(&c->refs);
3360	path->nodes[level] = c;
3361	path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
3362	path->slots[level] = 0;
3363	return 0;
3364}
3365
3366/*
3367 * worker function to insert a single pointer in a node.
3368 * the node should have enough room for the pointer already
3369 *
3370 * slot and level indicate where you want the key to go, and
3371 * blocknr is the block the key points to.
3372 */
3373static void insert_ptr(struct btrfs_trans_handle *trans,
3374		       struct btrfs_path *path,
3375		       struct btrfs_disk_key *key, u64 bytenr,
3376		       int slot, int level)
3377{
3378	struct extent_buffer *lower;
3379	int nritems;
3380	int ret;
3381
3382	BUG_ON(!path->nodes[level]);
3383	btrfs_assert_tree_locked(path->nodes[level]);
3384	lower = path->nodes[level];
3385	nritems = btrfs_header_nritems(lower);
3386	BUG_ON(slot > nritems);
3387	BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
3388	if (slot != nritems) {
3389		if (level) {
3390			ret = tree_mod_log_insert_move(lower, slot + 1, slot,
3391					nritems - slot);
3392			BUG_ON(ret < 0);
3393		}
3394		memmove_extent_buffer(lower,
3395			      btrfs_node_key_ptr_offset(slot + 1),
3396			      btrfs_node_key_ptr_offset(slot),
3397			      (nritems - slot) * sizeof(struct btrfs_key_ptr));
3398	}
3399	if (level) {
3400		ret = tree_mod_log_insert_key(lower, slot, MOD_LOG_KEY_ADD,
3401				GFP_NOFS);
3402		BUG_ON(ret < 0);
3403	}
3404	btrfs_set_node_key(lower, key, slot);
3405	btrfs_set_node_blockptr(lower, slot, bytenr);
3406	WARN_ON(trans->transid == 0);
3407	btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3408	btrfs_set_header_nritems(lower, nritems + 1);
3409	btrfs_mark_buffer_dirty(lower);
3410}
3411
3412/*
3413 * split the node at the specified level in path in two.
3414 * The path is corrected to point to the appropriate node after the split
3415 *
3416 * Before splitting this tries to make some room in the node by pushing
3417 * left and right, if either one works, it returns right away.
3418 *
3419 * returns 0 on success and < 0 on failure
3420 */
3421static noinline int split_node(struct btrfs_trans_handle *trans,
3422			       struct btrfs_root *root,
3423			       struct btrfs_path *path, int level)
3424{
3425	struct btrfs_fs_info *fs_info = root->fs_info;
3426	struct extent_buffer *c;
3427	struct extent_buffer *split;
3428	struct btrfs_disk_key disk_key;
3429	int mid;
3430	int ret;
3431	u32 c_nritems;
3432
3433	c = path->nodes[level];
3434	WARN_ON(btrfs_header_generation(c) != trans->transid);
3435	if (c == root->node) {
3436		/*
3437		 * trying to split the root, lets make a new one
3438		 *
3439		 * tree mod log: We don't log_removal old root in
3440		 * insert_new_root, because that root buffer will be kept as a
3441		 * normal node. We are going to log removal of half of the
3442		 * elements below with tree_mod_log_eb_copy. We're holding a
3443		 * tree lock on the buffer, which is why we cannot race with
3444		 * other tree_mod_log users.
3445		 */
3446		ret = insert_new_root(trans, root, path, level + 1);
3447		if (ret)
3448			return ret;
3449	} else {
3450		ret = push_nodes_for_insert(trans, root, path, level);
3451		c = path->nodes[level];
3452		if (!ret && btrfs_header_nritems(c) <
3453		    BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3454			return 0;
3455		if (ret < 0)
3456			return ret;
3457	}
3458
3459	c_nritems = btrfs_header_nritems(c);
3460	mid = (c_nritems + 1) / 2;
3461	btrfs_node_key(c, &disk_key, mid);
3462
3463	split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
3464					     c->start, 0);
3465	if (IS_ERR(split))
3466		return PTR_ERR(split);
3467
3468	root_add_used(root, fs_info->nodesize);
3469	ASSERT(btrfs_header_level(c) == level);
 
 
 
 
 
 
 
 
 
 
 
3470
3471	ret = tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
 
3472	if (ret) {
3473		btrfs_abort_transaction(trans, ret);
3474		return ret;
3475	}
3476	copy_extent_buffer(split, c,
3477			   btrfs_node_key_ptr_offset(0),
3478			   btrfs_node_key_ptr_offset(mid),
3479			   (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3480	btrfs_set_header_nritems(split, c_nritems - mid);
3481	btrfs_set_header_nritems(c, mid);
3482	ret = 0;
3483
3484	btrfs_mark_buffer_dirty(c);
3485	btrfs_mark_buffer_dirty(split);
3486
3487	insert_ptr(trans, path, &disk_key, split->start,
3488		   path->slots[level + 1] + 1, level + 1);
3489
3490	if (path->slots[level] >= mid) {
3491		path->slots[level] -= mid;
3492		btrfs_tree_unlock(c);
3493		free_extent_buffer(c);
3494		path->nodes[level] = split;
3495		path->slots[level + 1] += 1;
3496	} else {
3497		btrfs_tree_unlock(split);
3498		free_extent_buffer(split);
3499	}
3500	return ret;
3501}
3502
3503/*
3504 * how many bytes are required to store the items in a leaf.  start
3505 * and nr indicate which items in the leaf to check.  This totals up the
3506 * space used both by the item structs and the item data
3507 */
3508static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3509{
3510	struct btrfs_item *start_item;
3511	struct btrfs_item *end_item;
 
3512	int data_len;
3513	int nritems = btrfs_header_nritems(l);
3514	int end = min(nritems, start + nr) - 1;
3515
3516	if (!nr)
3517		return 0;
 
3518	start_item = btrfs_item_nr(start);
3519	end_item = btrfs_item_nr(end);
3520	data_len = btrfs_item_offset(l, start_item) +
3521		   btrfs_item_size(l, start_item);
3522	data_len = data_len - btrfs_item_offset(l, end_item);
3523	data_len += sizeof(struct btrfs_item) * nr;
3524	WARN_ON(data_len < 0);
3525	return data_len;
3526}
3527
3528/*
3529 * The space between the end of the leaf items and
3530 * the start of the leaf data.  IOW, how much room
3531 * the leaf has left for both items and data
3532 */
3533noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
 
3534{
3535	struct btrfs_fs_info *fs_info = leaf->fs_info;
3536	int nritems = btrfs_header_nritems(leaf);
3537	int ret;
3538
3539	ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3540	if (ret < 0) {
3541		btrfs_crit(fs_info,
3542			   "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3543			   ret,
3544			   (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3545			   leaf_space_used(leaf, 0, nritems), nritems);
3546	}
3547	return ret;
3548}
3549
3550/*
3551 * min slot controls the lowest index we're willing to push to the
3552 * right.  We'll push up to and including min_slot, but no lower
3553 */
3554static noinline int __push_leaf_right(struct btrfs_path *path,
 
 
3555				      int data_size, int empty,
3556				      struct extent_buffer *right,
3557				      int free_space, u32 left_nritems,
3558				      u32 min_slot)
3559{
3560	struct btrfs_fs_info *fs_info = right->fs_info;
3561	struct extent_buffer *left = path->nodes[0];
3562	struct extent_buffer *upper = path->nodes[1];
3563	struct btrfs_map_token token;
3564	struct btrfs_disk_key disk_key;
3565	int slot;
3566	u32 i;
3567	int push_space = 0;
3568	int push_items = 0;
3569	struct btrfs_item *item;
3570	u32 nr;
3571	u32 right_nritems;
3572	u32 data_end;
3573	u32 this_item_size;
3574
 
 
3575	if (empty)
3576		nr = 0;
3577	else
3578		nr = max_t(u32, 1, min_slot);
3579
3580	if (path->slots[0] >= left_nritems)
3581		push_space += data_size;
3582
3583	slot = path->slots[1];
3584	i = left_nritems - 1;
3585	while (i >= nr) {
3586		item = btrfs_item_nr(i);
3587
3588		if (!empty && push_items > 0) {
3589			if (path->slots[0] > i)
3590				break;
3591			if (path->slots[0] == i) {
3592				int space = btrfs_leaf_free_space(left);
3593
3594				if (space + push_space * 2 > free_space)
3595					break;
3596			}
3597		}
3598
3599		if (path->slots[0] == i)
3600			push_space += data_size;
3601
3602		this_item_size = btrfs_item_size(left, item);
3603		if (this_item_size + sizeof(*item) + push_space > free_space)
3604			break;
3605
3606		push_items++;
3607		push_space += this_item_size + sizeof(*item);
3608		if (i == 0)
3609			break;
3610		i--;
3611	}
3612
3613	if (push_items == 0)
3614		goto out_unlock;
3615
3616	WARN_ON(!empty && push_items == left_nritems);
3617
3618	/* push left to right */
3619	right_nritems = btrfs_header_nritems(right);
3620
3621	push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3622	push_space -= leaf_data_end(left);
3623
3624	/* make room in the right data area */
3625	data_end = leaf_data_end(right);
3626	memmove_extent_buffer(right,
3627			      BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
3628			      BTRFS_LEAF_DATA_OFFSET + data_end,
3629			      BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3630
3631	/* copy from the left data area */
3632	copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
3633		     BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3634		     BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
3635		     push_space);
3636
3637	memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3638			      btrfs_item_nr_offset(0),
3639			      right_nritems * sizeof(struct btrfs_item));
3640
3641	/* copy the items from left to right */
3642	copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3643		   btrfs_item_nr_offset(left_nritems - push_items),
3644		   push_items * sizeof(struct btrfs_item));
3645
3646	/* update the item pointers */
3647	btrfs_init_map_token(&token, right);
3648	right_nritems += push_items;
3649	btrfs_set_header_nritems(right, right_nritems);
3650	push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3651	for (i = 0; i < right_nritems; i++) {
3652		item = btrfs_item_nr(i);
3653		push_space -= btrfs_token_item_size(&token, item);
3654		btrfs_set_token_item_offset(&token, item, push_space);
3655	}
3656
3657	left_nritems -= push_items;
3658	btrfs_set_header_nritems(left, left_nritems);
3659
3660	if (left_nritems)
3661		btrfs_mark_buffer_dirty(left);
3662	else
3663		btrfs_clean_tree_block(left);
3664
3665	btrfs_mark_buffer_dirty(right);
3666
3667	btrfs_item_key(right, &disk_key, 0);
3668	btrfs_set_node_key(upper, &disk_key, slot + 1);
3669	btrfs_mark_buffer_dirty(upper);
3670
3671	/* then fixup the leaf pointer in the path */
3672	if (path->slots[0] >= left_nritems) {
3673		path->slots[0] -= left_nritems;
3674		if (btrfs_header_nritems(path->nodes[0]) == 0)
3675			btrfs_clean_tree_block(path->nodes[0]);
3676		btrfs_tree_unlock(path->nodes[0]);
3677		free_extent_buffer(path->nodes[0]);
3678		path->nodes[0] = right;
3679		path->slots[1] += 1;
3680	} else {
3681		btrfs_tree_unlock(right);
3682		free_extent_buffer(right);
3683	}
3684	return 0;
3685
3686out_unlock:
3687	btrfs_tree_unlock(right);
3688	free_extent_buffer(right);
3689	return 1;
3690}
3691
3692/*
3693 * push some data in the path leaf to the right, trying to free up at
3694 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3695 *
3696 * returns 1 if the push failed because the other node didn't have enough
3697 * room, 0 if everything worked out and < 0 if there were major errors.
3698 *
3699 * this will push starting from min_slot to the end of the leaf.  It won't
3700 * push any slot lower than min_slot
3701 */
3702static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3703			   *root, struct btrfs_path *path,
3704			   int min_data_size, int data_size,
3705			   int empty, u32 min_slot)
3706{
3707	struct extent_buffer *left = path->nodes[0];
3708	struct extent_buffer *right;
3709	struct extent_buffer *upper;
3710	int slot;
3711	int free_space;
3712	u32 left_nritems;
3713	int ret;
3714
3715	if (!path->nodes[1])
3716		return 1;
3717
3718	slot = path->slots[1];
3719	upper = path->nodes[1];
3720	if (slot >= btrfs_header_nritems(upper) - 1)
3721		return 1;
3722
3723	btrfs_assert_tree_locked(path->nodes[1]);
3724
3725	right = btrfs_read_node_slot(upper, slot + 1);
3726	/*
3727	 * slot + 1 is not valid or we fail to read the right node,
3728	 * no big deal, just return.
3729	 */
3730	if (IS_ERR(right))
3731		return 1;
3732
3733	btrfs_tree_lock(right);
3734	btrfs_set_lock_blocking_write(right);
3735
3736	free_space = btrfs_leaf_free_space(right);
3737	if (free_space < data_size)
3738		goto out_unlock;
3739
3740	/* cow and double check */
3741	ret = btrfs_cow_block(trans, root, right, upper,
3742			      slot + 1, &right);
3743	if (ret)
3744		goto out_unlock;
3745
3746	free_space = btrfs_leaf_free_space(right);
3747	if (free_space < data_size)
3748		goto out_unlock;
3749
3750	left_nritems = btrfs_header_nritems(left);
3751	if (left_nritems == 0)
3752		goto out_unlock;
3753
3754	if (path->slots[0] == left_nritems && !empty) {
3755		/* Key greater than all keys in the leaf, right neighbor has
3756		 * enough room for it and we're not emptying our leaf to delete
3757		 * it, therefore use right neighbor to insert the new item and
3758		 * no need to touch/dirty our left leaf. */
3759		btrfs_tree_unlock(left);
3760		free_extent_buffer(left);
3761		path->nodes[0] = right;
3762		path->slots[0] = 0;
3763		path->slots[1]++;
3764		return 0;
3765	}
3766
3767	return __push_leaf_right(path, min_data_size, empty,
3768				right, free_space, left_nritems, min_slot);
3769out_unlock:
3770	btrfs_tree_unlock(right);
3771	free_extent_buffer(right);
3772	return 1;
3773}
3774
3775/*
3776 * push some data in the path leaf to the left, trying to free up at
3777 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3778 *
3779 * max_slot can put a limit on how far into the leaf we'll push items.  The
3780 * item at 'max_slot' won't be touched.  Use (u32)-1 to make us do all the
3781 * items
3782 */
3783static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
 
 
3784				     int empty, struct extent_buffer *left,
3785				     int free_space, u32 right_nritems,
3786				     u32 max_slot)
3787{
3788	struct btrfs_fs_info *fs_info = left->fs_info;
3789	struct btrfs_disk_key disk_key;
3790	struct extent_buffer *right = path->nodes[0];
3791	int i;
3792	int push_space = 0;
3793	int push_items = 0;
3794	struct btrfs_item *item;
3795	u32 old_left_nritems;
3796	u32 nr;
3797	int ret = 0;
3798	u32 this_item_size;
3799	u32 old_left_item_size;
3800	struct btrfs_map_token token;
3801
 
 
3802	if (empty)
3803		nr = min(right_nritems, max_slot);
3804	else
3805		nr = min(right_nritems - 1, max_slot);
3806
3807	for (i = 0; i < nr; i++) {
3808		item = btrfs_item_nr(i);
3809
3810		if (!empty && push_items > 0) {
3811			if (path->slots[0] < i)
3812				break;
3813			if (path->slots[0] == i) {
3814				int space = btrfs_leaf_free_space(right);
3815
3816				if (space + push_space * 2 > free_space)
3817					break;
3818			}
3819		}
3820
3821		if (path->slots[0] == i)
3822			push_space += data_size;
3823
3824		this_item_size = btrfs_item_size(right, item);
3825		if (this_item_size + sizeof(*item) + push_space > free_space)
3826			break;
3827
3828		push_items++;
3829		push_space += this_item_size + sizeof(*item);
3830	}
3831
3832	if (push_items == 0) {
3833		ret = 1;
3834		goto out;
3835	}
3836	WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3837
3838	/* push data from right to left */
3839	copy_extent_buffer(left, right,
3840			   btrfs_item_nr_offset(btrfs_header_nritems(left)),
3841			   btrfs_item_nr_offset(0),
3842			   push_items * sizeof(struct btrfs_item));
3843
3844	push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3845		     btrfs_item_offset_nr(right, push_items - 1);
3846
3847	copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
3848		     leaf_data_end(left) - push_space,
3849		     BTRFS_LEAF_DATA_OFFSET +
3850		     btrfs_item_offset_nr(right, push_items - 1),
3851		     push_space);
3852	old_left_nritems = btrfs_header_nritems(left);
3853	BUG_ON(old_left_nritems <= 0);
3854
3855	btrfs_init_map_token(&token, left);
3856	old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3857	for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3858		u32 ioff;
3859
3860		item = btrfs_item_nr(i);
3861
3862		ioff = btrfs_token_item_offset(&token, item);
3863		btrfs_set_token_item_offset(&token, item,
3864		      ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
 
3865	}
3866	btrfs_set_header_nritems(left, old_left_nritems + push_items);
3867
3868	/* fixup right node */
3869	if (push_items > right_nritems)
3870		WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3871		       right_nritems);
3872
3873	if (push_items < right_nritems) {
3874		push_space = btrfs_item_offset_nr(right, push_items - 1) -
3875						  leaf_data_end(right);
3876		memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
3877				      BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3878				      BTRFS_LEAF_DATA_OFFSET +
3879				      leaf_data_end(right), push_space);
3880
3881		memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3882			      btrfs_item_nr_offset(push_items),
3883			     (btrfs_header_nritems(right) - push_items) *
3884			     sizeof(struct btrfs_item));
3885	}
3886
3887	btrfs_init_map_token(&token, right);
3888	right_nritems -= push_items;
3889	btrfs_set_header_nritems(right, right_nritems);
3890	push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3891	for (i = 0; i < right_nritems; i++) {
3892		item = btrfs_item_nr(i);
3893
3894		push_space = push_space - btrfs_token_item_size(&token, item);
3895		btrfs_set_token_item_offset(&token, item, push_space);
 
3896	}
3897
3898	btrfs_mark_buffer_dirty(left);
3899	if (right_nritems)
3900		btrfs_mark_buffer_dirty(right);
3901	else
3902		btrfs_clean_tree_block(right);
3903
3904	btrfs_item_key(right, &disk_key, 0);
3905	fixup_low_keys(path, &disk_key, 1);
3906
3907	/* then fixup the leaf pointer in the path */
3908	if (path->slots[0] < push_items) {
3909		path->slots[0] += old_left_nritems;
3910		btrfs_tree_unlock(path->nodes[0]);
3911		free_extent_buffer(path->nodes[0]);
3912		path->nodes[0] = left;
3913		path->slots[1] -= 1;
3914	} else {
3915		btrfs_tree_unlock(left);
3916		free_extent_buffer(left);
3917		path->slots[0] -= push_items;
3918	}
3919	BUG_ON(path->slots[0] < 0);
3920	return ret;
3921out:
3922	btrfs_tree_unlock(left);
3923	free_extent_buffer(left);
3924	return ret;
3925}
3926
3927/*
3928 * push some data in the path leaf to the left, trying to free up at
3929 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3930 *
3931 * max_slot can put a limit on how far into the leaf we'll push items.  The
3932 * item at 'max_slot' won't be touched.  Use (u32)-1 to make us push all the
3933 * items
3934 */
3935static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3936			  *root, struct btrfs_path *path, int min_data_size,
3937			  int data_size, int empty, u32 max_slot)
3938{
3939	struct extent_buffer *right = path->nodes[0];
3940	struct extent_buffer *left;
3941	int slot;
3942	int free_space;
3943	u32 right_nritems;
3944	int ret = 0;
3945
3946	slot = path->slots[1];
3947	if (slot == 0)
3948		return 1;
3949	if (!path->nodes[1])
3950		return 1;
3951
3952	right_nritems = btrfs_header_nritems(right);
3953	if (right_nritems == 0)
3954		return 1;
3955
3956	btrfs_assert_tree_locked(path->nodes[1]);
3957
3958	left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3959	/*
3960	 * slot - 1 is not valid or we fail to read the left node,
3961	 * no big deal, just return.
3962	 */
3963	if (IS_ERR(left))
3964		return 1;
3965
3966	btrfs_tree_lock(left);
3967	btrfs_set_lock_blocking_write(left);
3968
3969	free_space = btrfs_leaf_free_space(left);
3970	if (free_space < data_size) {
3971		ret = 1;
3972		goto out;
3973	}
3974
3975	/* cow and double check */
3976	ret = btrfs_cow_block(trans, root, left,
3977			      path->nodes[1], slot - 1, &left);
3978	if (ret) {
3979		/* we hit -ENOSPC, but it isn't fatal here */
3980		if (ret == -ENOSPC)
3981			ret = 1;
3982		goto out;
3983	}
3984
3985	free_space = btrfs_leaf_free_space(left);
3986	if (free_space < data_size) {
3987		ret = 1;
3988		goto out;
3989	}
3990
3991	return __push_leaf_left(path, min_data_size,
3992			       empty, left, free_space, right_nritems,
3993			       max_slot);
3994out:
3995	btrfs_tree_unlock(left);
3996	free_extent_buffer(left);
3997	return ret;
3998}
3999
4000/*
4001 * split the path's leaf in two, making sure there is at least data_size
4002 * available for the resulting leaf level of the path.
4003 */
4004static noinline void copy_for_split(struct btrfs_trans_handle *trans,
 
4005				    struct btrfs_path *path,
4006				    struct extent_buffer *l,
4007				    struct extent_buffer *right,
4008				    int slot, int mid, int nritems)
4009{
4010	struct btrfs_fs_info *fs_info = trans->fs_info;
4011	int data_copy_size;
4012	int rt_data_off;
4013	int i;
4014	struct btrfs_disk_key disk_key;
4015	struct btrfs_map_token token;
4016
 
 
4017	nritems = nritems - mid;
4018	btrfs_set_header_nritems(right, nritems);
4019	data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(l);
4020
4021	copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
4022			   btrfs_item_nr_offset(mid),
4023			   nritems * sizeof(struct btrfs_item));
4024
4025	copy_extent_buffer(right, l,
4026		     BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
4027		     data_copy_size, BTRFS_LEAF_DATA_OFFSET +
4028		     leaf_data_end(l), data_copy_size);
4029
4030	rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
 
4031
4032	btrfs_init_map_token(&token, right);
4033	for (i = 0; i < nritems; i++) {
4034		struct btrfs_item *item = btrfs_item_nr(i);
4035		u32 ioff;
4036
4037		ioff = btrfs_token_item_offset(&token, item);
4038		btrfs_set_token_item_offset(&token, item, ioff + rt_data_off);
 
4039	}
4040
4041	btrfs_set_header_nritems(l, mid);
4042	btrfs_item_key(right, &disk_key, 0);
4043	insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
 
4044
4045	btrfs_mark_buffer_dirty(right);
4046	btrfs_mark_buffer_dirty(l);
4047	BUG_ON(path->slots[0] != slot);
4048
4049	if (mid <= slot) {
4050		btrfs_tree_unlock(path->nodes[0]);
4051		free_extent_buffer(path->nodes[0]);
4052		path->nodes[0] = right;
4053		path->slots[0] -= mid;
4054		path->slots[1] += 1;
4055	} else {
4056		btrfs_tree_unlock(right);
4057		free_extent_buffer(right);
4058	}
4059
4060	BUG_ON(path->slots[0] < 0);
4061}
4062
4063/*
4064 * double splits happen when we need to insert a big item in the middle
4065 * of a leaf.  A double split can leave us with 3 mostly empty leaves:
4066 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
4067 *          A                 B                 C
4068 *
4069 * We avoid this by trying to push the items on either side of our target
4070 * into the adjacent leaves.  If all goes well we can avoid the double split
4071 * completely.
4072 */
4073static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
4074					  struct btrfs_root *root,
4075					  struct btrfs_path *path,
4076					  int data_size)
4077{
4078	int ret;
4079	int progress = 0;
4080	int slot;
4081	u32 nritems;
4082	int space_needed = data_size;
4083
4084	slot = path->slots[0];
4085	if (slot < btrfs_header_nritems(path->nodes[0]))
4086		space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4087
4088	/*
4089	 * try to push all the items after our slot into the
4090	 * right leaf
4091	 */
4092	ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
4093	if (ret < 0)
4094		return ret;
4095
4096	if (ret == 0)
4097		progress++;
4098
4099	nritems = btrfs_header_nritems(path->nodes[0]);
4100	/*
4101	 * our goal is to get our slot at the start or end of a leaf.  If
4102	 * we've done so we're done
4103	 */
4104	if (path->slots[0] == 0 || path->slots[0] == nritems)
4105		return 0;
4106
4107	if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4108		return 0;
4109
4110	/* try to push all the items before our slot into the next leaf */
4111	slot = path->slots[0];
4112	space_needed = data_size;
4113	if (slot > 0)
4114		space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4115	ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
4116	if (ret < 0)
4117		return ret;
4118
4119	if (ret == 0)
4120		progress++;
4121
4122	if (progress)
4123		return 0;
4124	return 1;
4125}
4126
4127/*
4128 * split the path's leaf in two, making sure there is at least data_size
4129 * available for the resulting leaf level of the path.
4130 *
4131 * returns 0 if all went well and < 0 on failure.
4132 */
4133static noinline int split_leaf(struct btrfs_trans_handle *trans,
4134			       struct btrfs_root *root,
4135			       const struct btrfs_key *ins_key,
4136			       struct btrfs_path *path, int data_size,
4137			       int extend)
4138{
4139	struct btrfs_disk_key disk_key;
4140	struct extent_buffer *l;
4141	u32 nritems;
4142	int mid;
4143	int slot;
4144	struct extent_buffer *right;
4145	struct btrfs_fs_info *fs_info = root->fs_info;
4146	int ret = 0;
4147	int wret;
4148	int split;
4149	int num_doubles = 0;
4150	int tried_avoid_double = 0;
4151
4152	l = path->nodes[0];
4153	slot = path->slots[0];
4154	if (extend && data_size + btrfs_item_size_nr(l, slot) +
4155	    sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
4156		return -EOVERFLOW;
4157
4158	/* first try to make some room by pushing left and right */
4159	if (data_size && path->nodes[1]) {
4160		int space_needed = data_size;
4161
4162		if (slot < btrfs_header_nritems(l))
4163			space_needed -= btrfs_leaf_free_space(l);
4164
4165		wret = push_leaf_right(trans, root, path, space_needed,
4166				       space_needed, 0, 0);
4167		if (wret < 0)
4168			return wret;
4169		if (wret) {
4170			space_needed = data_size;
4171			if (slot > 0)
4172				space_needed -= btrfs_leaf_free_space(l);
4173			wret = push_leaf_left(trans, root, path, space_needed,
4174					      space_needed, 0, (u32)-1);
4175			if (wret < 0)
4176				return wret;
4177		}
4178		l = path->nodes[0];
4179
4180		/* did the pushes work? */
4181		if (btrfs_leaf_free_space(l) >= data_size)
4182			return 0;
4183	}
4184
4185	if (!path->nodes[1]) {
4186		ret = insert_new_root(trans, root, path, 1);
4187		if (ret)
4188			return ret;
4189	}
4190again:
4191	split = 1;
4192	l = path->nodes[0];
4193	slot = path->slots[0];
4194	nritems = btrfs_header_nritems(l);
4195	mid = (nritems + 1) / 2;
4196
4197	if (mid <= slot) {
4198		if (nritems == 1 ||
4199		    leaf_space_used(l, mid, nritems - mid) + data_size >
4200			BTRFS_LEAF_DATA_SIZE(fs_info)) {
4201			if (slot >= nritems) {
4202				split = 0;
4203			} else {
4204				mid = slot;
4205				if (mid != nritems &&
4206				    leaf_space_used(l, mid, nritems - mid) +
4207				    data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4208					if (data_size && !tried_avoid_double)
4209						goto push_for_double;
4210					split = 2;
4211				}
4212			}
4213		}
4214	} else {
4215		if (leaf_space_used(l, 0, mid) + data_size >
4216			BTRFS_LEAF_DATA_SIZE(fs_info)) {
4217			if (!extend && data_size && slot == 0) {
4218				split = 0;
4219			} else if ((extend || !data_size) && slot == 0) {
4220				mid = 1;
4221			} else {
4222				mid = slot;
4223				if (mid != nritems &&
4224				    leaf_space_used(l, mid, nritems - mid) +
4225				    data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4226					if (data_size && !tried_avoid_double)
4227						goto push_for_double;
4228					split = 2;
4229				}
4230			}
4231		}
4232	}
4233
4234	if (split == 0)
4235		btrfs_cpu_key_to_disk(&disk_key, ins_key);
4236	else
4237		btrfs_item_key(l, &disk_key, mid);
4238
4239	right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
4240					     l->start, 0);
4241	if (IS_ERR(right))
4242		return PTR_ERR(right);
4243
4244	root_add_used(root, fs_info->nodesize);
 
 
 
 
 
 
 
 
 
 
 
 
 
4245
4246	if (split == 0) {
4247		if (mid <= slot) {
4248			btrfs_set_header_nritems(right, 0);
4249			insert_ptr(trans, path, &disk_key,
4250				   right->start, path->slots[1] + 1, 1);
4251			btrfs_tree_unlock(path->nodes[0]);
4252			free_extent_buffer(path->nodes[0]);
4253			path->nodes[0] = right;
4254			path->slots[0] = 0;
4255			path->slots[1] += 1;
4256		} else {
4257			btrfs_set_header_nritems(right, 0);
4258			insert_ptr(trans, path, &disk_key,
4259				   right->start, path->slots[1], 1);
4260			btrfs_tree_unlock(path->nodes[0]);
4261			free_extent_buffer(path->nodes[0]);
4262			path->nodes[0] = right;
4263			path->slots[0] = 0;
4264			if (path->slots[1] == 0)
4265				fixup_low_keys(path, &disk_key, 1);
4266		}
4267		/*
4268		 * We create a new leaf 'right' for the required ins_len and
4269		 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
4270		 * the content of ins_len to 'right'.
4271		 */
4272		return ret;
4273	}
4274
4275	copy_for_split(trans, path, l, right, slot, mid, nritems);
4276
4277	if (split == 2) {
4278		BUG_ON(num_doubles != 0);
4279		num_doubles++;
4280		goto again;
4281	}
4282
4283	return 0;
4284
4285push_for_double:
4286	push_for_double_split(trans, root, path, data_size);
4287	tried_avoid_double = 1;
4288	if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4289		return 0;
4290	goto again;
4291}
4292
4293static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4294					 struct btrfs_root *root,
4295					 struct btrfs_path *path, int ins_len)
4296{
4297	struct btrfs_key key;
4298	struct extent_buffer *leaf;
4299	struct btrfs_file_extent_item *fi;
4300	u64 extent_len = 0;
4301	u32 item_size;
4302	int ret;
4303
4304	leaf = path->nodes[0];
4305	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4306
4307	BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4308	       key.type != BTRFS_EXTENT_CSUM_KEY);
4309
4310	if (btrfs_leaf_free_space(leaf) >= ins_len)
4311		return 0;
4312
4313	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4314	if (key.type == BTRFS_EXTENT_DATA_KEY) {
4315		fi = btrfs_item_ptr(leaf, path->slots[0],
4316				    struct btrfs_file_extent_item);
4317		extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4318	}
4319	btrfs_release_path(path);
4320
4321	path->keep_locks = 1;
4322	path->search_for_split = 1;
4323	ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4324	path->search_for_split = 0;
4325	if (ret > 0)
4326		ret = -EAGAIN;
4327	if (ret < 0)
4328		goto err;
4329
4330	ret = -EAGAIN;
4331	leaf = path->nodes[0];
4332	/* if our item isn't there, return now */
4333	if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4334		goto err;
4335
4336	/* the leaf has  changed, it now has room.  return now */
4337	if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
4338		goto err;
4339
4340	if (key.type == BTRFS_EXTENT_DATA_KEY) {
4341		fi = btrfs_item_ptr(leaf, path->slots[0],
4342				    struct btrfs_file_extent_item);
4343		if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4344			goto err;
4345	}
4346
4347	btrfs_set_path_blocking(path);
4348	ret = split_leaf(trans, root, &key, path, ins_len, 1);
4349	if (ret)
4350		goto err;
4351
4352	path->keep_locks = 0;
4353	btrfs_unlock_up_safe(path, 1);
4354	return 0;
4355err:
4356	path->keep_locks = 0;
4357	return ret;
4358}
4359
4360static noinline int split_item(struct btrfs_path *path,
4361			       const struct btrfs_key *new_key,
 
 
4362			       unsigned long split_offset)
4363{
4364	struct extent_buffer *leaf;
4365	struct btrfs_item *item;
4366	struct btrfs_item *new_item;
4367	int slot;
4368	char *buf;
4369	u32 nritems;
4370	u32 item_size;
4371	u32 orig_offset;
4372	struct btrfs_disk_key disk_key;
4373
4374	leaf = path->nodes[0];
4375	BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
4376
4377	btrfs_set_path_blocking(path);
4378
4379	item = btrfs_item_nr(path->slots[0]);
4380	orig_offset = btrfs_item_offset(leaf, item);
4381	item_size = btrfs_item_size(leaf, item);
4382
4383	buf = kmalloc(item_size, GFP_NOFS);
4384	if (!buf)
4385		return -ENOMEM;
4386
4387	read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4388			    path->slots[0]), item_size);
4389
4390	slot = path->slots[0] + 1;
4391	nritems = btrfs_header_nritems(leaf);
4392	if (slot != nritems) {
4393		/* shift the items */
4394		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4395				btrfs_item_nr_offset(slot),
4396				(nritems - slot) * sizeof(struct btrfs_item));
4397	}
4398
4399	btrfs_cpu_key_to_disk(&disk_key, new_key);
4400	btrfs_set_item_key(leaf, &disk_key, slot);
4401
4402	new_item = btrfs_item_nr(slot);
4403
4404	btrfs_set_item_offset(leaf, new_item, orig_offset);
4405	btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4406
4407	btrfs_set_item_offset(leaf, item,
4408			      orig_offset + item_size - split_offset);
4409	btrfs_set_item_size(leaf, item, split_offset);
4410
4411	btrfs_set_header_nritems(leaf, nritems + 1);
4412
4413	/* write the data for the start of the original item */
4414	write_extent_buffer(leaf, buf,
4415			    btrfs_item_ptr_offset(leaf, path->slots[0]),
4416			    split_offset);
4417
4418	/* write the data for the new item */
4419	write_extent_buffer(leaf, buf + split_offset,
4420			    btrfs_item_ptr_offset(leaf, slot),
4421			    item_size - split_offset);
4422	btrfs_mark_buffer_dirty(leaf);
4423
4424	BUG_ON(btrfs_leaf_free_space(leaf) < 0);
4425	kfree(buf);
4426	return 0;
4427}
4428
4429/*
4430 * This function splits a single item into two items,
4431 * giving 'new_key' to the new item and splitting the
4432 * old one at split_offset (from the start of the item).
4433 *
4434 * The path may be released by this operation.  After
4435 * the split, the path is pointing to the old item.  The
4436 * new item is going to be in the same node as the old one.
4437 *
4438 * Note, the item being split must be smaller enough to live alone on
4439 * a tree block with room for one extra struct btrfs_item
4440 *
4441 * This allows us to split the item in place, keeping a lock on the
4442 * leaf the entire time.
4443 */
4444int btrfs_split_item(struct btrfs_trans_handle *trans,
4445		     struct btrfs_root *root,
4446		     struct btrfs_path *path,
4447		     const struct btrfs_key *new_key,
4448		     unsigned long split_offset)
4449{
4450	int ret;
4451	ret = setup_leaf_for_split(trans, root, path,
4452				   sizeof(struct btrfs_item));
4453	if (ret)
4454		return ret;
4455
4456	ret = split_item(path, new_key, split_offset);
4457	return ret;
4458}
4459
4460/*
4461 * This function duplicate a item, giving 'new_key' to the new item.
4462 * It guarantees both items live in the same tree leaf and the new item
4463 * is contiguous with the original item.
4464 *
4465 * This allows us to split file extent in place, keeping a lock on the
4466 * leaf the entire time.
4467 */
4468int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4469			 struct btrfs_root *root,
4470			 struct btrfs_path *path,
4471			 const struct btrfs_key *new_key)
4472{
4473	struct extent_buffer *leaf;
4474	int ret;
4475	u32 item_size;
4476
4477	leaf = path->nodes[0];
4478	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4479	ret = setup_leaf_for_split(trans, root, path,
4480				   item_size + sizeof(struct btrfs_item));
4481	if (ret)
4482		return ret;
4483
4484	path->slots[0]++;
4485	setup_items_for_insert(root, path, new_key, &item_size,
4486			       item_size, item_size +
4487			       sizeof(struct btrfs_item), 1);
4488	leaf = path->nodes[0];
4489	memcpy_extent_buffer(leaf,
4490			     btrfs_item_ptr_offset(leaf, path->slots[0]),
4491			     btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4492			     item_size);
4493	return 0;
4494}
4495
4496/*
4497 * make the item pointed to by the path smaller.  new_size indicates
4498 * how small to make it, and from_end tells us if we just chop bytes
4499 * off the end of the item or if we shift the item to chop bytes off
4500 * the front.
4501 */
4502void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
 
4503{
4504	int slot;
4505	struct extent_buffer *leaf;
4506	struct btrfs_item *item;
4507	u32 nritems;
4508	unsigned int data_end;
4509	unsigned int old_data_start;
4510	unsigned int old_size;
4511	unsigned int size_diff;
4512	int i;
4513	struct btrfs_map_token token;
4514
 
 
4515	leaf = path->nodes[0];
4516	slot = path->slots[0];
4517
4518	old_size = btrfs_item_size_nr(leaf, slot);
4519	if (old_size == new_size)
4520		return;
4521
4522	nritems = btrfs_header_nritems(leaf);
4523	data_end = leaf_data_end(leaf);
4524
4525	old_data_start = btrfs_item_offset_nr(leaf, slot);
4526
4527	size_diff = old_size - new_size;
4528
4529	BUG_ON(slot < 0);
4530	BUG_ON(slot >= nritems);
4531
4532	/*
4533	 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4534	 */
4535	/* first correct the data pointers */
4536	btrfs_init_map_token(&token, leaf);
4537	for (i = slot; i < nritems; i++) {
4538		u32 ioff;
4539		item = btrfs_item_nr(i);
4540
4541		ioff = btrfs_token_item_offset(&token, item);
4542		btrfs_set_token_item_offset(&token, item, ioff + size_diff);
 
4543	}
4544
4545	/* shift the data */
4546	if (from_end) {
4547		memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4548			      data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4549			      data_end, old_data_start + new_size - data_end);
4550	} else {
4551		struct btrfs_disk_key disk_key;
4552		u64 offset;
4553
4554		btrfs_item_key(leaf, &disk_key, slot);
4555
4556		if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4557			unsigned long ptr;
4558			struct btrfs_file_extent_item *fi;
4559
4560			fi = btrfs_item_ptr(leaf, slot,
4561					    struct btrfs_file_extent_item);
4562			fi = (struct btrfs_file_extent_item *)(
4563			     (unsigned long)fi - size_diff);
4564
4565			if (btrfs_file_extent_type(leaf, fi) ==
4566			    BTRFS_FILE_EXTENT_INLINE) {
4567				ptr = btrfs_item_ptr_offset(leaf, slot);
4568				memmove_extent_buffer(leaf, ptr,
4569				      (unsigned long)fi,
4570				      BTRFS_FILE_EXTENT_INLINE_DATA_START);
4571			}
4572		}
4573
4574		memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4575			      data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4576			      data_end, old_data_start - data_end);
4577
4578		offset = btrfs_disk_key_offset(&disk_key);
4579		btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4580		btrfs_set_item_key(leaf, &disk_key, slot);
4581		if (slot == 0)
4582			fixup_low_keys(path, &disk_key, 1);
4583	}
4584
4585	item = btrfs_item_nr(slot);
4586	btrfs_set_item_size(leaf, item, new_size);
4587	btrfs_mark_buffer_dirty(leaf);
4588
4589	if (btrfs_leaf_free_space(leaf) < 0) {
4590		btrfs_print_leaf(leaf);
4591		BUG();
4592	}
4593}
4594
4595/*
4596 * make the item pointed to by the path bigger, data_size is the added size.
4597 */
4598void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
 
4599{
4600	int slot;
4601	struct extent_buffer *leaf;
4602	struct btrfs_item *item;
4603	u32 nritems;
4604	unsigned int data_end;
4605	unsigned int old_data;
4606	unsigned int old_size;
4607	int i;
4608	struct btrfs_map_token token;
4609
 
 
4610	leaf = path->nodes[0];
4611
4612	nritems = btrfs_header_nritems(leaf);
4613	data_end = leaf_data_end(leaf);
4614
4615	if (btrfs_leaf_free_space(leaf) < data_size) {
4616		btrfs_print_leaf(leaf);
4617		BUG();
4618	}
4619	slot = path->slots[0];
4620	old_data = btrfs_item_end_nr(leaf, slot);
4621
4622	BUG_ON(slot < 0);
4623	if (slot >= nritems) {
4624		btrfs_print_leaf(leaf);
4625		btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4626			   slot, nritems);
4627		BUG();
4628	}
4629
4630	/*
4631	 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4632	 */
4633	/* first correct the data pointers */
4634	btrfs_init_map_token(&token, leaf);
4635	for (i = slot; i < nritems; i++) {
4636		u32 ioff;
4637		item = btrfs_item_nr(i);
4638
4639		ioff = btrfs_token_item_offset(&token, item);
4640		btrfs_set_token_item_offset(&token, item, ioff - data_size);
 
4641	}
4642
4643	/* shift the data */
4644	memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4645		      data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
4646		      data_end, old_data - data_end);
4647
4648	data_end = old_data;
4649	old_size = btrfs_item_size_nr(leaf, slot);
4650	item = btrfs_item_nr(slot);
4651	btrfs_set_item_size(leaf, item, old_size + data_size);
4652	btrfs_mark_buffer_dirty(leaf);
4653
4654	if (btrfs_leaf_free_space(leaf) < 0) {
4655		btrfs_print_leaf(leaf);
4656		BUG();
4657	}
4658}
4659
4660/*
4661 * this is a helper for btrfs_insert_empty_items, the main goal here is
4662 * to save stack depth by doing the bulk of the work in a function
4663 * that doesn't call btrfs_search_slot
4664 */
4665void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4666			    const struct btrfs_key *cpu_key, u32 *data_size,
4667			    u32 total_data, u32 total_size, int nr)
4668{
4669	struct btrfs_fs_info *fs_info = root->fs_info;
4670	struct btrfs_item *item;
4671	int i;
4672	u32 nritems;
4673	unsigned int data_end;
4674	struct btrfs_disk_key disk_key;
4675	struct extent_buffer *leaf;
4676	int slot;
4677	struct btrfs_map_token token;
4678
4679	if (path->slots[0] == 0) {
4680		btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4681		fixup_low_keys(path, &disk_key, 1);
4682	}
4683	btrfs_unlock_up_safe(path, 1);
4684
 
 
4685	leaf = path->nodes[0];
4686	slot = path->slots[0];
4687
4688	nritems = btrfs_header_nritems(leaf);
4689	data_end = leaf_data_end(leaf);
4690
4691	if (btrfs_leaf_free_space(leaf) < total_size) {
4692		btrfs_print_leaf(leaf);
4693		btrfs_crit(fs_info, "not enough freespace need %u have %d",
4694			   total_size, btrfs_leaf_free_space(leaf));
4695		BUG();
4696	}
4697
4698	btrfs_init_map_token(&token, leaf);
4699	if (slot != nritems) {
4700		unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4701
4702		if (old_data < data_end) {
4703			btrfs_print_leaf(leaf);
4704			btrfs_crit(fs_info, "slot %d old_data %d data_end %d",
4705				   slot, old_data, data_end);
4706			BUG();
4707		}
4708		/*
4709		 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4710		 */
4711		/* first correct the data pointers */
4712		for (i = slot; i < nritems; i++) {
4713			u32 ioff;
4714
4715			item = btrfs_item_nr(i);
4716			ioff = btrfs_token_item_offset(&token, item);
4717			btrfs_set_token_item_offset(&token, item,
4718						    ioff - total_data);
4719		}
4720		/* shift the items */
4721		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4722			      btrfs_item_nr_offset(slot),
4723			      (nritems - slot) * sizeof(struct btrfs_item));
4724
4725		/* shift the data */
4726		memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4727			      data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
4728			      data_end, old_data - data_end);
4729		data_end = old_data;
4730	}
4731
4732	/* setup the item for the new data */
4733	for (i = 0; i < nr; i++) {
4734		btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4735		btrfs_set_item_key(leaf, &disk_key, slot + i);
4736		item = btrfs_item_nr(slot + i);
4737		btrfs_set_token_item_offset(&token, item, data_end - data_size[i]);
 
4738		data_end -= data_size[i];
4739		btrfs_set_token_item_size(&token, item, data_size[i]);
4740	}
4741
4742	btrfs_set_header_nritems(leaf, nritems + nr);
4743	btrfs_mark_buffer_dirty(leaf);
4744
4745	if (btrfs_leaf_free_space(leaf) < 0) {
4746		btrfs_print_leaf(leaf);
4747		BUG();
4748	}
4749}
4750
4751/*
4752 * Given a key and some data, insert items into the tree.
4753 * This does all the path init required, making room in the tree if needed.
4754 */
4755int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4756			    struct btrfs_root *root,
4757			    struct btrfs_path *path,
4758			    const struct btrfs_key *cpu_key, u32 *data_size,
4759			    int nr)
4760{
4761	int ret = 0;
4762	int slot;
4763	int i;
4764	u32 total_size = 0;
4765	u32 total_data = 0;
4766
4767	for (i = 0; i < nr; i++)
4768		total_data += data_size[i];
4769
4770	total_size = total_data + (nr * sizeof(struct btrfs_item));
4771	ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4772	if (ret == 0)
4773		return -EEXIST;
4774	if (ret < 0)
4775		return ret;
4776
4777	slot = path->slots[0];
4778	BUG_ON(slot < 0);
4779
4780	setup_items_for_insert(root, path, cpu_key, data_size,
4781			       total_data, total_size, nr);
4782	return 0;
4783}
4784
4785/*
4786 * Given a key and some data, insert an item into the tree.
4787 * This does all the path init required, making room in the tree if needed.
4788 */
4789int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4790		      const struct btrfs_key *cpu_key, void *data,
4791		      u32 data_size)
4792{
4793	int ret = 0;
4794	struct btrfs_path *path;
4795	struct extent_buffer *leaf;
4796	unsigned long ptr;
4797
4798	path = btrfs_alloc_path();
4799	if (!path)
4800		return -ENOMEM;
4801	ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4802	if (!ret) {
4803		leaf = path->nodes[0];
4804		ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4805		write_extent_buffer(leaf, data, ptr, data_size);
4806		btrfs_mark_buffer_dirty(leaf);
4807	}
4808	btrfs_free_path(path);
4809	return ret;
4810}
4811
4812/*
4813 * delete the pointer from a given node.
4814 *
4815 * the tree should have been previously balanced so the deletion does not
4816 * empty a node.
4817 */
4818static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4819		    int level, int slot)
4820{
4821	struct extent_buffer *parent = path->nodes[level];
4822	u32 nritems;
4823	int ret;
4824
4825	nritems = btrfs_header_nritems(parent);
4826	if (slot != nritems - 1) {
4827		if (level) {
4828			ret = tree_mod_log_insert_move(parent, slot, slot + 1,
4829					nritems - slot - 1);
4830			BUG_ON(ret < 0);
4831		}
4832		memmove_extent_buffer(parent,
4833			      btrfs_node_key_ptr_offset(slot),
4834			      btrfs_node_key_ptr_offset(slot + 1),
4835			      sizeof(struct btrfs_key_ptr) *
4836			      (nritems - slot - 1));
4837	} else if (level) {
4838		ret = tree_mod_log_insert_key(parent, slot, MOD_LOG_KEY_REMOVE,
4839				GFP_NOFS);
4840		BUG_ON(ret < 0);
4841	}
4842
4843	nritems--;
4844	btrfs_set_header_nritems(parent, nritems);
4845	if (nritems == 0 && parent == root->node) {
4846		BUG_ON(btrfs_header_level(root->node) != 1);
4847		/* just turn the root into a leaf and break */
4848		btrfs_set_header_level(root->node, 0);
4849	} else if (slot == 0) {
4850		struct btrfs_disk_key disk_key;
4851
4852		btrfs_node_key(parent, &disk_key, 0);
4853		fixup_low_keys(path, &disk_key, level + 1);
4854	}
4855	btrfs_mark_buffer_dirty(parent);
4856}
4857
4858/*
4859 * a helper function to delete the leaf pointed to by path->slots[1] and
4860 * path->nodes[1].
4861 *
4862 * This deletes the pointer in path->nodes[1] and frees the leaf
4863 * block extent.  zero is returned if it all worked out, < 0 otherwise.
4864 *
4865 * The path must have already been setup for deleting the leaf, including
4866 * all the proper balancing.  path->nodes[1] must be locked.
4867 */
4868static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4869				    struct btrfs_root *root,
4870				    struct btrfs_path *path,
4871				    struct extent_buffer *leaf)
4872{
4873	WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4874	del_ptr(root, path, 1, path->slots[1]);
4875
4876	/*
4877	 * btrfs_free_extent is expensive, we want to make sure we
4878	 * aren't holding any locks when we call it
4879	 */
4880	btrfs_unlock_up_safe(path, 0);
4881
4882	root_sub_used(root, leaf->len);
4883
4884	atomic_inc(&leaf->refs);
4885	btrfs_free_tree_block(trans, root, leaf, 0, 1);
4886	free_extent_buffer_stale(leaf);
4887}
4888/*
4889 * delete the item at the leaf level in path.  If that empties
4890 * the leaf, remove it from the tree
4891 */
4892int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4893		    struct btrfs_path *path, int slot, int nr)
4894{
4895	struct btrfs_fs_info *fs_info = root->fs_info;
4896	struct extent_buffer *leaf;
4897	struct btrfs_item *item;
4898	u32 last_off;
4899	u32 dsize = 0;
4900	int ret = 0;
4901	int wret;
4902	int i;
4903	u32 nritems;
 
 
 
4904
4905	leaf = path->nodes[0];
4906	last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4907
4908	for (i = 0; i < nr; i++)
4909		dsize += btrfs_item_size_nr(leaf, slot + i);
4910
4911	nritems = btrfs_header_nritems(leaf);
4912
4913	if (slot + nr != nritems) {
4914		int data_end = leaf_data_end(leaf);
4915		struct btrfs_map_token token;
4916
4917		memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4918			      data_end + dsize,
4919			      BTRFS_LEAF_DATA_OFFSET + data_end,
4920			      last_off - data_end);
4921
4922		btrfs_init_map_token(&token, leaf);
4923		for (i = slot + nr; i < nritems; i++) {
4924			u32 ioff;
4925
4926			item = btrfs_item_nr(i);
4927			ioff = btrfs_token_item_offset(&token, item);
4928			btrfs_set_token_item_offset(&token, item, ioff + dsize);
 
4929		}
4930
4931		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4932			      btrfs_item_nr_offset(slot + nr),
4933			      sizeof(struct btrfs_item) *
4934			      (nritems - slot - nr));
4935	}
4936	btrfs_set_header_nritems(leaf, nritems - nr);
4937	nritems -= nr;
4938
4939	/* delete the leaf if we've emptied it */
4940	if (nritems == 0) {
4941		if (leaf == root->node) {
4942			btrfs_set_header_level(leaf, 0);
4943		} else {
4944			btrfs_set_path_blocking(path);
4945			btrfs_clean_tree_block(leaf);
4946			btrfs_del_leaf(trans, root, path, leaf);
4947		}
4948	} else {
4949		int used = leaf_space_used(leaf, 0, nritems);
4950		if (slot == 0) {
4951			struct btrfs_disk_key disk_key;
4952
4953			btrfs_item_key(leaf, &disk_key, 0);
4954			fixup_low_keys(path, &disk_key, 1);
4955		}
4956
4957		/* delete the leaf if it is mostly empty */
4958		if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4959			/* push_leaf_left fixes the path.
4960			 * make sure the path still points to our leaf
4961			 * for possible call to del_ptr below
4962			 */
4963			slot = path->slots[1];
4964			atomic_inc(&leaf->refs);
4965
4966			btrfs_set_path_blocking(path);
4967			wret = push_leaf_left(trans, root, path, 1, 1,
4968					      1, (u32)-1);
4969			if (wret < 0 && wret != -ENOSPC)
4970				ret = wret;
4971
4972			if (path->nodes[0] == leaf &&
4973			    btrfs_header_nritems(leaf)) {
4974				wret = push_leaf_right(trans, root, path, 1,
4975						       1, 1, 0);
4976				if (wret < 0 && wret != -ENOSPC)
4977					ret = wret;
4978			}
4979
4980			if (btrfs_header_nritems(leaf) == 0) {
4981				path->slots[1] = slot;
4982				btrfs_del_leaf(trans, root, path, leaf);
4983				free_extent_buffer(leaf);
4984				ret = 0;
4985			} else {
4986				/* if we're still in the path, make sure
4987				 * we're dirty.  Otherwise, one of the
4988				 * push_leaf functions must have already
4989				 * dirtied this buffer
4990				 */
4991				if (path->nodes[0] == leaf)
4992					btrfs_mark_buffer_dirty(leaf);
4993				free_extent_buffer(leaf);
4994			}
4995		} else {
4996			btrfs_mark_buffer_dirty(leaf);
4997		}
4998	}
4999	return ret;
5000}
5001
5002/*
5003 * search the tree again to find a leaf with lesser keys
5004 * returns 0 if it found something or 1 if there are no lesser leaves.
5005 * returns < 0 on io errors.
5006 *
5007 * This may release the path, and so you may lose any locks held at the
5008 * time you call it.
5009 */
5010int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
5011{
5012	struct btrfs_key key;
5013	struct btrfs_disk_key found_key;
5014	int ret;
5015
5016	btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
5017
5018	if (key.offset > 0) {
5019		key.offset--;
5020	} else if (key.type > 0) {
5021		key.type--;
5022		key.offset = (u64)-1;
5023	} else if (key.objectid > 0) {
5024		key.objectid--;
5025		key.type = (u8)-1;
5026		key.offset = (u64)-1;
5027	} else {
5028		return 1;
5029	}
5030
5031	btrfs_release_path(path);
5032	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5033	if (ret < 0)
5034		return ret;
5035	btrfs_item_key(path->nodes[0], &found_key, 0);
5036	ret = comp_keys(&found_key, &key);
5037	/*
5038	 * We might have had an item with the previous key in the tree right
5039	 * before we released our path. And after we released our path, that
5040	 * item might have been pushed to the first slot (0) of the leaf we
5041	 * were holding due to a tree balance. Alternatively, an item with the
5042	 * previous key can exist as the only element of a leaf (big fat item).
5043	 * Therefore account for these 2 cases, so that our callers (like
5044	 * btrfs_previous_item) don't miss an existing item with a key matching
5045	 * the previous key we computed above.
5046	 */
5047	if (ret <= 0)
5048		return 0;
5049	return 1;
5050}
5051
5052/*
5053 * A helper function to walk down the tree starting at min_key, and looking
5054 * for nodes or leaves that are have a minimum transaction id.
5055 * This is used by the btree defrag code, and tree logging
5056 *
5057 * This does not cow, but it does stuff the starting key it finds back
5058 * into min_key, so you can call btrfs_search_slot with cow=1 on the
5059 * key and get a writable path.
5060 *
 
 
 
5061 * This honors path->lowest_level to prevent descent past a given level
5062 * of the tree.
5063 *
5064 * min_trans indicates the oldest transaction that you are interested
5065 * in walking through.  Any nodes or leaves older than min_trans are
5066 * skipped over (without reading them).
5067 *
5068 * returns zero if something useful was found, < 0 on error and 1 if there
5069 * was nothing in the tree that matched the search criteria.
5070 */
5071int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
5072			 struct btrfs_path *path,
5073			 u64 min_trans)
5074{
5075	struct extent_buffer *cur;
5076	struct btrfs_key found_key;
5077	int slot;
5078	int sret;
5079	u32 nritems;
5080	int level;
5081	int ret = 1;
5082	int keep_locks = path->keep_locks;
5083
5084	path->keep_locks = 1;
5085again:
5086	cur = btrfs_read_lock_root_node(root);
5087	level = btrfs_header_level(cur);
5088	WARN_ON(path->nodes[level]);
5089	path->nodes[level] = cur;
5090	path->locks[level] = BTRFS_READ_LOCK;
5091
5092	if (btrfs_header_generation(cur) < min_trans) {
5093		ret = 1;
5094		goto out;
5095	}
5096	while (1) {
5097		nritems = btrfs_header_nritems(cur);
5098		level = btrfs_header_level(cur);
5099		sret = btrfs_bin_search(cur, min_key, &slot);
5100		if (sret < 0) {
5101			ret = sret;
5102			goto out;
5103		}
5104
5105		/* at the lowest level, we're done, setup the path and exit */
5106		if (level == path->lowest_level) {
5107			if (slot >= nritems)
5108				goto find_next_key;
5109			ret = 0;
5110			path->slots[level] = slot;
5111			btrfs_item_key_to_cpu(cur, &found_key, slot);
5112			goto out;
5113		}
5114		if (sret && slot > 0)
5115			slot--;
5116		/*
5117		 * check this node pointer against the min_trans parameters.
5118		 * If it is too old, old, skip to the next one.
5119		 */
5120		while (slot < nritems) {
5121			u64 gen;
5122
5123			gen = btrfs_node_ptr_generation(cur, slot);
5124			if (gen < min_trans) {
5125				slot++;
5126				continue;
5127			}
5128			break;
5129		}
5130find_next_key:
5131		/*
5132		 * we didn't find a candidate key in this node, walk forward
5133		 * and find another one
5134		 */
5135		if (slot >= nritems) {
5136			path->slots[level] = slot;
5137			btrfs_set_path_blocking(path);
5138			sret = btrfs_find_next_key(root, path, min_key, level,
5139						  min_trans);
5140			if (sret == 0) {
5141				btrfs_release_path(path);
5142				goto again;
5143			} else {
5144				goto out;
5145			}
5146		}
5147		/* save our key for returning back */
5148		btrfs_node_key_to_cpu(cur, &found_key, slot);
5149		path->slots[level] = slot;
5150		if (level == path->lowest_level) {
5151			ret = 0;
5152			goto out;
5153		}
5154		btrfs_set_path_blocking(path);
5155		cur = btrfs_read_node_slot(cur, slot);
5156		if (IS_ERR(cur)) {
5157			ret = PTR_ERR(cur);
5158			goto out;
5159		}
5160
5161		btrfs_tree_read_lock(cur);
5162
5163		path->locks[level - 1] = BTRFS_READ_LOCK;
5164		path->nodes[level - 1] = cur;
5165		unlock_up(path, level, 1, 0, NULL);
 
5166	}
5167out:
5168	path->keep_locks = keep_locks;
5169	if (ret == 0) {
5170		btrfs_unlock_up_safe(path, path->lowest_level + 1);
5171		btrfs_set_path_blocking(path);
5172		memcpy(min_key, &found_key, sizeof(found_key));
5173	}
5174	return ret;
5175}
5176
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5177/*
5178 * this is similar to btrfs_next_leaf, but does not try to preserve
5179 * and fixup the path.  It looks for and returns the next key in the
5180 * tree based on the current path and the min_trans parameters.
5181 *
5182 * 0 is returned if another key is found, < 0 if there are any errors
5183 * and 1 is returned if there are no higher keys in the tree
5184 *
5185 * path->keep_locks should be set to 1 on the search made before
5186 * calling this function.
5187 */
5188int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5189			struct btrfs_key *key, int level, u64 min_trans)
5190{
5191	int slot;
5192	struct extent_buffer *c;
5193
5194	WARN_ON(!path->keep_locks && !path->skip_locking);
5195	while (level < BTRFS_MAX_LEVEL) {
5196		if (!path->nodes[level])
5197			return 1;
5198
5199		slot = path->slots[level] + 1;
5200		c = path->nodes[level];
5201next:
5202		if (slot >= btrfs_header_nritems(c)) {
5203			int ret;
5204			int orig_lowest;
5205			struct btrfs_key cur_key;
5206			if (level + 1 >= BTRFS_MAX_LEVEL ||
5207			    !path->nodes[level + 1])
5208				return 1;
5209
5210			if (path->locks[level + 1] || path->skip_locking) {
5211				level++;
5212				continue;
5213			}
5214
5215			slot = btrfs_header_nritems(c) - 1;
5216			if (level == 0)
5217				btrfs_item_key_to_cpu(c, &cur_key, slot);
5218			else
5219				btrfs_node_key_to_cpu(c, &cur_key, slot);
5220
5221			orig_lowest = path->lowest_level;
5222			btrfs_release_path(path);
5223			path->lowest_level = level;
5224			ret = btrfs_search_slot(NULL, root, &cur_key, path,
5225						0, 0);
5226			path->lowest_level = orig_lowest;
5227			if (ret < 0)
5228				return ret;
5229
5230			c = path->nodes[level];
5231			slot = path->slots[level];
5232			if (ret == 0)
5233				slot++;
5234			goto next;
5235		}
5236
5237		if (level == 0)
5238			btrfs_item_key_to_cpu(c, key, slot);
5239		else {
5240			u64 gen = btrfs_node_ptr_generation(c, slot);
5241
5242			if (gen < min_trans) {
5243				slot++;
5244				goto next;
5245			}
5246			btrfs_node_key_to_cpu(c, key, slot);
5247		}
5248		return 0;
5249	}
5250	return 1;
5251}
5252
5253/*
5254 * search the tree again to find a leaf with greater keys
5255 * returns 0 if it found something or 1 if there are no greater leaves.
5256 * returns < 0 on io errors.
5257 */
5258int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5259{
5260	return btrfs_next_old_leaf(root, path, 0);
5261}
5262
5263int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5264			u64 time_seq)
5265{
5266	int slot;
5267	int level;
5268	struct extent_buffer *c;
5269	struct extent_buffer *next;
5270	struct btrfs_key key;
5271	u32 nritems;
5272	int ret;
5273	int old_spinning = path->leave_spinning;
5274	int next_rw_lock = 0;
5275
5276	nritems = btrfs_header_nritems(path->nodes[0]);
5277	if (nritems == 0)
5278		return 1;
5279
5280	btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5281again:
5282	level = 1;
5283	next = NULL;
5284	next_rw_lock = 0;
5285	btrfs_release_path(path);
5286
5287	path->keep_locks = 1;
5288	path->leave_spinning = 1;
5289
5290	if (time_seq)
5291		ret = btrfs_search_old_slot(root, &key, path, time_seq);
5292	else
5293		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5294	path->keep_locks = 0;
5295
5296	if (ret < 0)
5297		return ret;
5298
5299	nritems = btrfs_header_nritems(path->nodes[0]);
5300	/*
5301	 * by releasing the path above we dropped all our locks.  A balance
5302	 * could have added more items next to the key that used to be
5303	 * at the very end of the block.  So, check again here and
5304	 * advance the path if there are now more items available.
5305	 */
5306	if (nritems > 0 && path->slots[0] < nritems - 1) {
5307		if (ret == 0)
5308			path->slots[0]++;
5309		ret = 0;
5310		goto done;
5311	}
5312	/*
5313	 * So the above check misses one case:
5314	 * - after releasing the path above, someone has removed the item that
5315	 *   used to be at the very end of the block, and balance between leafs
5316	 *   gets another one with bigger key.offset to replace it.
5317	 *
5318	 * This one should be returned as well, or we can get leaf corruption
5319	 * later(esp. in __btrfs_drop_extents()).
5320	 *
5321	 * And a bit more explanation about this check,
5322	 * with ret > 0, the key isn't found, the path points to the slot
5323	 * where it should be inserted, so the path->slots[0] item must be the
5324	 * bigger one.
5325	 */
5326	if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
5327		ret = 0;
5328		goto done;
5329	}
5330
5331	while (level < BTRFS_MAX_LEVEL) {
5332		if (!path->nodes[level]) {
5333			ret = 1;
5334			goto done;
5335		}
5336
5337		slot = path->slots[level] + 1;
5338		c = path->nodes[level];
5339		if (slot >= btrfs_header_nritems(c)) {
5340			level++;
5341			if (level == BTRFS_MAX_LEVEL) {
5342				ret = 1;
5343				goto done;
5344			}
5345			continue;
5346		}
5347
5348		if (next) {
5349			btrfs_tree_unlock_rw(next, next_rw_lock);
5350			free_extent_buffer(next);
5351		}
5352
5353		next = c;
5354		next_rw_lock = path->locks[level];
5355		ret = read_block_for_search(root, path, &next, level,
5356					    slot, &key);
5357		if (ret == -EAGAIN)
5358			goto again;
5359
5360		if (ret < 0) {
5361			btrfs_release_path(path);
5362			goto done;
5363		}
5364
5365		if (!path->skip_locking) {
5366			ret = btrfs_try_tree_read_lock(next);
5367			if (!ret && time_seq) {
5368				/*
5369				 * If we don't get the lock, we may be racing
5370				 * with push_leaf_left, holding that lock while
5371				 * itself waiting for the leaf we've currently
5372				 * locked. To solve this situation, we give up
5373				 * on our lock and cycle.
5374				 */
5375				free_extent_buffer(next);
5376				btrfs_release_path(path);
5377				cond_resched();
5378				goto again;
5379			}
5380			if (!ret) {
5381				btrfs_set_path_blocking(path);
5382				btrfs_tree_read_lock(next);
 
 
5383			}
5384			next_rw_lock = BTRFS_READ_LOCK;
5385		}
5386		break;
5387	}
5388	path->slots[level] = slot;
5389	while (1) {
5390		level--;
5391		c = path->nodes[level];
5392		if (path->locks[level])
5393			btrfs_tree_unlock_rw(c, path->locks[level]);
5394
5395		free_extent_buffer(c);
5396		path->nodes[level] = next;
5397		path->slots[level] = 0;
5398		if (!path->skip_locking)
5399			path->locks[level] = next_rw_lock;
5400		if (!level)
5401			break;
5402
5403		ret = read_block_for_search(root, path, &next, level,
5404					    0, &key);
5405		if (ret == -EAGAIN)
5406			goto again;
5407
5408		if (ret < 0) {
5409			btrfs_release_path(path);
5410			goto done;
5411		}
5412
5413		if (!path->skip_locking) {
5414			ret = btrfs_try_tree_read_lock(next);
5415			if (!ret) {
5416				btrfs_set_path_blocking(path);
5417				btrfs_tree_read_lock(next);
 
 
5418			}
5419			next_rw_lock = BTRFS_READ_LOCK;
5420		}
5421	}
5422	ret = 0;
5423done:
5424	unlock_up(path, 0, 1, 0, NULL);
5425	path->leave_spinning = old_spinning;
5426	if (!old_spinning)
5427		btrfs_set_path_blocking(path);
5428
5429	return ret;
5430}
5431
5432/*
5433 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5434 * searching until it gets past min_objectid or finds an item of 'type'
5435 *
5436 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5437 */
5438int btrfs_previous_item(struct btrfs_root *root,
5439			struct btrfs_path *path, u64 min_objectid,
5440			int type)
5441{
5442	struct btrfs_key found_key;
5443	struct extent_buffer *leaf;
5444	u32 nritems;
5445	int ret;
5446
5447	while (1) {
5448		if (path->slots[0] == 0) {
5449			btrfs_set_path_blocking(path);
5450			ret = btrfs_prev_leaf(root, path);
5451			if (ret != 0)
5452				return ret;
5453		} else {
5454			path->slots[0]--;
5455		}
5456		leaf = path->nodes[0];
5457		nritems = btrfs_header_nritems(leaf);
5458		if (nritems == 0)
5459			return 1;
5460		if (path->slots[0] == nritems)
5461			path->slots[0]--;
5462
5463		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5464		if (found_key.objectid < min_objectid)
5465			break;
5466		if (found_key.type == type)
5467			return 0;
5468		if (found_key.objectid == min_objectid &&
5469		    found_key.type < type)
5470			break;
5471	}
5472	return 1;
5473}
5474
5475/*
5476 * search in extent tree to find a previous Metadata/Data extent item with
5477 * min objecitd.
5478 *
5479 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5480 */
5481int btrfs_previous_extent_item(struct btrfs_root *root,
5482			struct btrfs_path *path, u64 min_objectid)
5483{
5484	struct btrfs_key found_key;
5485	struct extent_buffer *leaf;
5486	u32 nritems;
5487	int ret;
5488
5489	while (1) {
5490		if (path->slots[0] == 0) {
5491			btrfs_set_path_blocking(path);
5492			ret = btrfs_prev_leaf(root, path);
5493			if (ret != 0)
5494				return ret;
5495		} else {
5496			path->slots[0]--;
5497		}
5498		leaf = path->nodes[0];
5499		nritems = btrfs_header_nritems(leaf);
5500		if (nritems == 0)
5501			return 1;
5502		if (path->slots[0] == nritems)
5503			path->slots[0]--;
5504
5505		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5506		if (found_key.objectid < min_objectid)
5507			break;
5508		if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5509		    found_key.type == BTRFS_METADATA_ITEM_KEY)
5510			return 0;
5511		if (found_key.objectid == min_objectid &&
5512		    found_key.type < BTRFS_EXTENT_ITEM_KEY)
5513			break;
5514	}
5515	return 1;
5516}