1/*
   2 * Copyright (C) 2007,2008 Oracle.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public
   6 * License v2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 * General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public
  14 * License along with this program; if not, write to the
  15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16 * Boston, MA 021110-1307, USA.
  17 */
  18
  19#include <linux/sched.h>
  20#include <linux/slab.h>
  21#include <linux/rbtree.h>
 
  22#include "ctree.h"
  23#include "disk-io.h"
  24#include "transaction.h"
  25#include "print-tree.h"
  26#include "locking.h"
  27
  28static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  29		      *root, struct btrfs_path *path, int level);
  30static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
  31		      *root, struct btrfs_key *ins_key,
  32		      struct btrfs_path *path, int data_size, int extend);
  33static int push_node_left(struct btrfs_trans_handle *trans,
  34			  struct btrfs_root *root, struct extent_buffer *dst,
 
  35			  struct extent_buffer *src, int empty);
  36static int balance_node_right(struct btrfs_trans_handle *trans,
  37			      struct btrfs_root *root,
  38			      struct extent_buffer *dst_buf,
  39			      struct extent_buffer *src_buf);
  40static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  41		    struct btrfs_path *path, int level, int slot,
  42		    int tree_mod_log);
  43static void tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
  44				 struct extent_buffer *eb);
  45struct extent_buffer *read_old_tree_block(struct btrfs_root *root, u64 bytenr,
  46					  u32 blocksize, u64 parent_transid,
  47					  u64 time_seq);
  48struct extent_buffer *btrfs_find_old_tree_block(struct btrfs_root *root,
  49						u64 bytenr, u32 blocksize,
  50						u64 time_seq);
  51
  52struct btrfs_path *btrfs_alloc_path(void)
  53{
  54	struct btrfs_path *path;
  55	path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
  56	return path;
  57}
  58
  59/*
  60 * set all locked nodes in the path to blocking locks.  This should
  61 * be done before scheduling
  62 */
  63noinline void btrfs_set_path_blocking(struct btrfs_path *p)
  64{
  65	int i;
  66	for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  67		if (!p->nodes[i] || !p->locks[i])
  68			continue;
  69		btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]);
  70		if (p->locks[i] == BTRFS_READ_LOCK)
  71			p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
  72		else if (p->locks[i] == BTRFS_WRITE_LOCK)
  73			p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
  74	}
  75}
  76
  77/*
  78 * reset all the locked nodes in the patch to spinning locks.
  79 *
  80 * held is used to keep lockdep happy, when lockdep is enabled
  81 * we set held to a blocking lock before we go around and
  82 * retake all the spinlocks in the path.  You can safely use NULL
  83 * for held
  84 */
  85noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
  86					struct extent_buffer *held, int held_rw)
  87{
  88	int i;
  89
  90#ifdef CONFIG_DEBUG_LOCK_ALLOC
  91	/* lockdep really cares that we take all of these spinlocks
  92	 * in the right order.  If any of the locks in the path are not
  93	 * currently blocking, it is going to complain.  So, make really
  94	 * really sure by forcing the path to blocking before we clear
  95	 * the path blocking.
  96	 */
  97	if (held) {
  98		btrfs_set_lock_blocking_rw(held, held_rw);
  99		if (held_rw == BTRFS_WRITE_LOCK)
 100			held_rw = BTRFS_WRITE_LOCK_BLOCKING;
 101		else if (held_rw == BTRFS_READ_LOCK)
 102			held_rw = BTRFS_READ_LOCK_BLOCKING;
 103	}
 104	btrfs_set_path_blocking(p);
 105#endif
 106
 107	for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
 108		if (p->nodes[i] && p->locks[i]) {
 109			btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]);
 110			if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING)
 111				p->locks[i] = BTRFS_WRITE_LOCK;
 112			else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING)
 113				p->locks[i] = BTRFS_READ_LOCK;
 114		}
 115	}
 116
 117#ifdef CONFIG_DEBUG_LOCK_ALLOC
 118	if (held)
 119		btrfs_clear_lock_blocking_rw(held, held_rw);
 120#endif
 121}
 122
 123/* this also releases the path */
 124void btrfs_free_path(struct btrfs_path *p)
 125{
 126	if (!p)
 127		return;
 128	btrfs_release_path(p);
 129	kmem_cache_free(btrfs_path_cachep, p);
 130}
 131
 132/*
 133 * path release drops references on the extent buffers in the path
 134 * and it drops any locks held by this path
 135 *
 136 * It is safe to call this on paths that no locks or extent buffers held.
 137 */
 138noinline void btrfs_release_path(struct btrfs_path *p)
 139{
 140	int i;
 141
 142	for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
 143		p->slots[i] = 0;
 144		if (!p->nodes[i])
 145			continue;
 146		if (p->locks[i]) {
 147			btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
 148			p->locks[i] = 0;
 149		}
 150		free_extent_buffer(p->nodes[i]);
 151		p->nodes[i] = NULL;
 152	}
 153}
 154
 155/*
 156 * safely gets a reference on the root node of a tree.  A lock
 157 * is not taken, so a concurrent writer may put a different node
 158 * at the root of the tree.  See btrfs_lock_root_node for the
 159 * looping required.
 160 *
 161 * The extent buffer returned by this has a reference taken, so
 162 * it won't disappear.  It may stop being the root of the tree
 163 * at any time because there are no locks held.
 164 */
 165struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
 166{
 167	struct extent_buffer *eb;
 168
 169	while (1) {
 170		rcu_read_lock();
 171		eb = rcu_dereference(root->node);
 172
 173		/*
 174		 * RCU really hurts here, we could free up the root node because
 175		 * it was cow'ed but we may not get the new root node yet so do
 176		 * the inc_not_zero dance and if it doesn't work then
 177		 * synchronize_rcu and try again.
 178		 */
 179		if (atomic_inc_not_zero(&eb->refs)) {
 180			rcu_read_unlock();
 181			break;
 182		}
 183		rcu_read_unlock();
 184		synchronize_rcu();
 185	}
 186	return eb;
 187}
 188
 189/* loop around taking references on and locking the root node of the
 190 * tree until you end up with a lock on the root.  A locked buffer
 191 * is returned, with a reference held.
 192 */
 193struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
 194{
 195	struct extent_buffer *eb;
 196
 197	while (1) {
 198		eb = btrfs_root_node(root);
 199		btrfs_tree_lock(eb);
 200		if (eb == root->node)
 201			break;
 202		btrfs_tree_unlock(eb);
 203		free_extent_buffer(eb);
 204	}
 205	return eb;
 206}
 207
 208/* loop around taking references on and locking the root node of the
 209 * tree until you end up with a lock on the root.  A locked buffer
 210 * is returned, with a reference held.
 211 */
 212struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
 213{
 214	struct extent_buffer *eb;
 215
 216	while (1) {
 217		eb = btrfs_root_node(root);
 218		btrfs_tree_read_lock(eb);
 219		if (eb == root->node)
 220			break;
 221		btrfs_tree_read_unlock(eb);
 222		free_extent_buffer(eb);
 223	}
 224	return eb;
 225}
 226
 227/* cowonly root (everything not a reference counted cow subvolume), just get
 228 * put onto a simple dirty list.  transaction.c walks this to make sure they
 229 * get properly updated on disk.
 230 */
 231static void add_root_to_dirty_list(struct btrfs_root *root)
 232{
 233	spin_lock(&root->fs_info->trans_lock);
 234	if (root->track_dirty && list_empty(&root->dirty_list)) {
 235		list_add(&root->dirty_list,
 236			 &root->fs_info->dirty_cowonly_roots);
 
 
 
 
 
 
 
 
 
 
 
 237	}
 238	spin_unlock(&root->fs_info->trans_lock);
 239}
 240
 241/*
 242 * used by snapshot creation to make a copy of a root for a tree with
 243 * a given objectid.  The buffer with the new root node is returned in
 244 * cow_ret, and this func returns zero on success or a negative error code.
 245 */
 246int btrfs_copy_root(struct btrfs_trans_handle *trans,
 247		      struct btrfs_root *root,
 248		      struct extent_buffer *buf,
 249		      struct extent_buffer **cow_ret, u64 new_root_objectid)
 250{
 
 251	struct extent_buffer *cow;
 252	int ret = 0;
 253	int level;
 254	struct btrfs_disk_key disk_key;
 255
 256	WARN_ON(root->ref_cows && trans->transid !=
 257		root->fs_info->running_transaction->transid);
 258	WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 
 259
 260	level = btrfs_header_level(buf);
 261	if (level == 0)
 262		btrfs_item_key(buf, &disk_key, 0);
 263	else
 264		btrfs_node_key(buf, &disk_key, 0);
 265
 266	cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
 267				     new_root_objectid, &disk_key, level,
 268				     buf->start, 0);
 269	if (IS_ERR(cow))
 270		return PTR_ERR(cow);
 271
 272	copy_extent_buffer(cow, buf, 0, 0, cow->len);
 273	btrfs_set_header_bytenr(cow, cow->start);
 274	btrfs_set_header_generation(cow, trans->transid);
 275	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 276	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 277				     BTRFS_HEADER_FLAG_RELOC);
 278	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 279		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 280	else
 281		btrfs_set_header_owner(cow, new_root_objectid);
 282
 283	write_extent_buffer(cow, root->fs_info->fsid,
 284			    (unsigned long)btrfs_header_fsid(cow),
 285			    BTRFS_FSID_SIZE);
 286
 287	WARN_ON(btrfs_header_generation(buf) > trans->transid);
 288	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 289		ret = btrfs_inc_ref(trans, root, cow, 1, 1);
 290	else
 291		ret = btrfs_inc_ref(trans, root, cow, 0, 1);
 292
 293	if (ret)
 294		return ret;
 295
 296	btrfs_mark_buffer_dirty(cow);
 297	*cow_ret = cow;
 298	return 0;
 299}
 300
 301enum mod_log_op {
 302	MOD_LOG_KEY_REPLACE,
 303	MOD_LOG_KEY_ADD,
 304	MOD_LOG_KEY_REMOVE,
 305	MOD_LOG_KEY_REMOVE_WHILE_FREEING,
 306	MOD_LOG_KEY_REMOVE_WHILE_MOVING,
 307	MOD_LOG_MOVE_KEYS,
 308	MOD_LOG_ROOT_REPLACE,
 309};
 310
 311struct tree_mod_move {
 312	int dst_slot;
 313	int nr_items;
 314};
 315
 316struct tree_mod_root {
 317	u64 logical;
 318	u8 level;
 319};
 320
 321struct tree_mod_elem {
 322	struct rb_node node;
 323	u64 index;		/* shifted logical */
 324	struct seq_list elem;
 325	enum mod_log_op op;
 326
 327	/* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
 328	int slot;
 329
 330	/* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
 331	u64 generation;
 332
 333	/* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
 334	struct btrfs_disk_key key;
 335	u64 blockptr;
 336
 337	/* this is used for op == MOD_LOG_MOVE_KEYS */
 338	struct tree_mod_move move;
 339
 340	/* this is used for op == MOD_LOG_ROOT_REPLACE */
 341	struct tree_mod_root old_root;
 342};
 343
 344static inline void
 345__get_tree_mod_seq(struct btrfs_fs_info *fs_info, struct seq_list *elem)
 346{
 347	elem->seq = atomic_inc_return(&fs_info->tree_mod_seq);
 348	list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
 349}
 350
 351void btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
 352			    struct seq_list *elem)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 353{
 354	elem->flags = 1;
 355	spin_lock(&fs_info->tree_mod_seq_lock);
 356	__get_tree_mod_seq(fs_info, elem);
 
 
 
 357	spin_unlock(&fs_info->tree_mod_seq_lock);
 
 
 
 358}
 359
 360void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
 361			    struct seq_list *elem)
 362{
 363	struct rb_root *tm_root;
 364	struct rb_node *node;
 365	struct rb_node *next;
 366	struct seq_list *cur_elem;
 367	struct tree_mod_elem *tm;
 368	u64 min_seq = (u64)-1;
 369	u64 seq_putting = elem->seq;
 370
 371	if (!seq_putting)
 372		return;
 373
 374	BUG_ON(!(elem->flags & 1));
 375	spin_lock(&fs_info->tree_mod_seq_lock);
 376	list_del(&elem->list);
 
 377
 378	list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
 379		if ((cur_elem->flags & 1) && cur_elem->seq < min_seq) {
 380			if (seq_putting > cur_elem->seq) {
 381				/*
 382				 * blocker with lower sequence number exists, we
 383				 * cannot remove anything from the log
 384				 */
 385				goto out;
 
 386			}
 387			min_seq = cur_elem->seq;
 388		}
 389	}
 
 390
 391	/*
 392	 * anything that's lower than the lowest existing (read: blocked)
 393	 * sequence number can be removed from the tree.
 394	 */
 395	write_lock(&fs_info->tree_mod_log_lock);
 396	tm_root = &fs_info->tree_mod_log;
 397	for (node = rb_first(tm_root); node; node = next) {
 398		next = rb_next(node);
 399		tm = container_of(node, struct tree_mod_elem, node);
 400		if (tm->elem.seq > min_seq)
 401			continue;
 402		rb_erase(node, tm_root);
 403		list_del(&tm->elem.list);
 404		kfree(tm);
 405	}
 406	write_unlock(&fs_info->tree_mod_log_lock);
 407out:
 408	spin_unlock(&fs_info->tree_mod_seq_lock);
 409}
 410
 411/*
 412 * key order of the log:
 413 *       index -> sequence
 414 *
 415 * the index is the shifted logical of the *new* root node for root replace
 416 * operations, or the shifted logical of the affected block for all other
 417 * operations.
 
 
 418 */
 419static noinline int
 420__tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
 421{
 422	struct rb_root *tm_root;
 423	struct rb_node **new;
 424	struct rb_node *parent = NULL;
 425	struct tree_mod_elem *cur;
 426	int ret = 0;
 427
 428	BUG_ON(!tm || !tm->elem.seq);
 
 
 429
 430	write_lock(&fs_info->tree_mod_log_lock);
 431	tm_root = &fs_info->tree_mod_log;
 432	new = &tm_root->rb_node;
 433	while (*new) {
 434		cur = container_of(*new, struct tree_mod_elem, node);
 435		parent = *new;
 436		if (cur->index < tm->index)
 437			new = &((*new)->rb_left);
 438		else if (cur->index > tm->index)
 439			new = &((*new)->rb_right);
 440		else if (cur->elem.seq < tm->elem.seq)
 441			new = &((*new)->rb_left);
 442		else if (cur->elem.seq > tm->elem.seq)
 443			new = &((*new)->rb_right);
 444		else {
 445			kfree(tm);
 446			ret = -EEXIST;
 447			goto unlock;
 448		}
 449	}
 450
 451	rb_link_node(&tm->node, parent, new);
 452	rb_insert_color(&tm->node, tm_root);
 453unlock:
 454	write_unlock(&fs_info->tree_mod_log_lock);
 455	return ret;
 456}
 457
 
 
 
 
 
 
 458static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
 459				    struct extent_buffer *eb) {
 460	smp_mb();
 461	if (list_empty(&(fs_info)->tree_mod_seq_list))
 462		return 1;
 463	if (!eb)
 464		return 0;
 465	if (btrfs_header_level(eb) == 0)
 466		return 1;
 
 
 
 
 
 
 
 467	return 0;
 468}
 469
 470/*
 471 * This allocates memory and gets a tree modification sequence number when
 472 * needed.
 473 *
 474 * Returns 0 when no sequence number is needed, < 0 on error.
 475 * Returns 1 when a sequence number was added. In this case,
 476 * fs_info->tree_mod_seq_lock was acquired and must be released by the caller
 477 * after inserting into the rb tree.
 478 */
 479static inline int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags,
 480				 struct tree_mod_elem **tm_ret)
 481{
 482	struct tree_mod_elem *tm;
 483	int seq;
 484
 485	if (tree_mod_dont_log(fs_info, NULL))
 486		return 0;
 487
 488	tm = *tm_ret = kzalloc(sizeof(*tm), flags);
 489	if (!tm)
 490		return -ENOMEM;
 491
 492	tm->elem.flags = 0;
 493	spin_lock(&fs_info->tree_mod_seq_lock);
 494	if (list_empty(&fs_info->tree_mod_seq_list)) {
 495		/*
 496		 * someone emptied the list while we were waiting for the lock.
 497		 * we must not add to the list, because no blocker exists. items
 498		 * are removed from the list only when the existing blocker is
 499		 * removed from the list.
 500		 */
 501		kfree(tm);
 502		seq = 0;
 503		spin_unlock(&fs_info->tree_mod_seq_lock);
 504	} else {
 505		__get_tree_mod_seq(fs_info, &tm->elem);
 506		seq = tm->elem.seq;
 507	}
 508
 509	return seq;
 510}
 511
 512static noinline int
 513tree_mod_log_insert_key_mask(struct btrfs_fs_info *fs_info,
 514			     struct extent_buffer *eb, int slot,
 515			     enum mod_log_op op, gfp_t flags)
 516{
 517	struct tree_mod_elem *tm;
 518	int ret;
 519
 520	ret = tree_mod_alloc(fs_info, flags, &tm);
 521	if (ret <= 0)
 522		return ret;
 523
 524	tm->index = eb->start >> PAGE_CACHE_SHIFT;
 525	if (op != MOD_LOG_KEY_ADD) {
 526		btrfs_node_key(eb, &tm->key, slot);
 527		tm->blockptr = btrfs_node_blockptr(eb, slot);
 528	}
 529	tm->op = op;
 530	tm->slot = slot;
 531	tm->generation = btrfs_node_ptr_generation(eb, slot);
 
 532
 533	ret = __tree_mod_log_insert(fs_info, tm);
 534	spin_unlock(&fs_info->tree_mod_seq_lock);
 535	return ret;
 536}
 537
 538static noinline int
 539tree_mod_log_insert_key(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
 540			int slot, enum mod_log_op op)
 
 541{
 542	return tree_mod_log_insert_key_mask(fs_info, eb, slot, op, GFP_NOFS);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 543}
 544
 545static noinline int
 546tree_mod_log_insert_move(struct btrfs_fs_info *fs_info,
 547			 struct extent_buffer *eb, int dst_slot, int src_slot,
 548			 int nr_items, gfp_t flags)
 549{
 550	struct tree_mod_elem *tm;
 551	int ret;
 
 552	int i;
 
 553
 554	if (tree_mod_dont_log(fs_info, eb))
 555		return 0;
 556
 557	for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
 558		ret = tree_mod_log_insert_key(fs_info, eb, i + dst_slot,
 559					      MOD_LOG_KEY_REMOVE_WHILE_MOVING);
 560		BUG_ON(ret < 0);
 561	}
 562
 563	ret = tree_mod_alloc(fs_info, flags, &tm);
 564	if (ret <= 0)
 565		return ret;
 
 
 566
 567	tm->index = eb->start >> PAGE_CACHE_SHIFT;
 568	tm->slot = src_slot;
 569	tm->move.dst_slot = dst_slot;
 570	tm->move.nr_items = nr_items;
 571	tm->op = MOD_LOG_MOVE_KEYS;
 572
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 573	ret = __tree_mod_log_insert(fs_info, tm);
 574	spin_unlock(&fs_info->tree_mod_seq_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 575	return ret;
 576}
 577
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 578static noinline int
 579tree_mod_log_insert_root(struct btrfs_fs_info *fs_info,
 580			 struct extent_buffer *old_root,
 581			 struct extent_buffer *new_root, gfp_t flags)
 
 582{
 583	struct tree_mod_elem *tm;
 584	int ret;
 
 
 
 585
 586	ret = tree_mod_alloc(fs_info, flags, &tm);
 587	if (ret <= 0)
 588		return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 589
 590	tm->index = new_root->start >> PAGE_CACHE_SHIFT;
 591	tm->old_root.logical = old_root->start;
 592	tm->old_root.level = btrfs_header_level(old_root);
 593	tm->generation = btrfs_header_generation(old_root);
 594	tm->op = MOD_LOG_ROOT_REPLACE;
 595
 596	ret = __tree_mod_log_insert(fs_info, tm);
 597	spin_unlock(&fs_info->tree_mod_seq_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 598	return ret;
 599}
 600
 601static struct tree_mod_elem *
 602__tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
 603		      int smallest)
 604{
 605	struct rb_root *tm_root;
 606	struct rb_node *node;
 607	struct tree_mod_elem *cur = NULL;
 608	struct tree_mod_elem *found = NULL;
 609	u64 index = start >> PAGE_CACHE_SHIFT;
 610
 611	read_lock(&fs_info->tree_mod_log_lock);
 612	tm_root = &fs_info->tree_mod_log;
 613	node = tm_root->rb_node;
 614	while (node) {
 615		cur = container_of(node, struct tree_mod_elem, node);
 616		if (cur->index < index) {
 617			node = node->rb_left;
 618		} else if (cur->index > index) {
 619			node = node->rb_right;
 620		} else if (cur->elem.seq < min_seq) {
 621			node = node->rb_left;
 622		} else if (!smallest) {
 623			/* we want the node with the highest seq */
 624			if (found)
 625				BUG_ON(found->elem.seq > cur->elem.seq);
 626			found = cur;
 627			node = node->rb_left;
 628		} else if (cur->elem.seq > min_seq) {
 629			/* we want the node with the smallest seq */
 630			if (found)
 631				BUG_ON(found->elem.seq < cur->elem.seq);
 632			found = cur;
 633			node = node->rb_right;
 634		} else {
 635			found = cur;
 636			break;
 637		}
 638	}
 639	read_unlock(&fs_info->tree_mod_log_lock);
 640
 641	return found;
 642}
 643
 644/*
 645 * this returns the element from the log with the smallest time sequence
 646 * value that's in the log (the oldest log item). any element with a time
 647 * sequence lower than min_seq will be ignored.
 648 */
 649static struct tree_mod_elem *
 650tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
 651			   u64 min_seq)
 652{
 653	return __tree_mod_log_search(fs_info, start, min_seq, 1);
 654}
 655
 656/*
 657 * this returns the element from the log with the largest time sequence
 658 * value that's in the log (the most recent log item). any element with
 659 * a time sequence lower than min_seq will be ignored.
 660 */
 661static struct tree_mod_elem *
 662tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
 663{
 664	return __tree_mod_log_search(fs_info, start, min_seq, 0);
 665}
 666
 667static inline void
 668tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
 669		     struct extent_buffer *src, unsigned long dst_offset,
 670		     unsigned long src_offset, int nr_items)
 671{
 672	int ret;
 
 
 673	int i;
 
 674
 675	if (tree_mod_dont_log(fs_info, NULL))
 676		return;
 677
 678	if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
 679		return;
 680
 681	/* speed this up by single seq for all operations? */
 
 
 
 
 
 
 682	for (i = 0; i < nr_items; i++) {
 683		ret = tree_mod_log_insert_key(fs_info, src, i + src_offset,
 684					      MOD_LOG_KEY_REMOVE);
 685		BUG_ON(ret < 0);
 686		ret = tree_mod_log_insert_key(fs_info, dst, i + dst_offset,
 687					      MOD_LOG_KEY_ADD);
 688		BUG_ON(ret < 0);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 689	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 690}
 691
 692static inline void
 693tree_mod_log_eb_move(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
 694		     int dst_offset, int src_offset, int nr_items)
 695{
 696	int ret;
 697	ret = tree_mod_log_insert_move(fs_info, dst, dst_offset, src_offset,
 698				       nr_items, GFP_NOFS);
 699	BUG_ON(ret < 0);
 700}
 701
 702static inline void
 703tree_mod_log_set_node_key(struct btrfs_fs_info *fs_info,
 704			  struct extent_buffer *eb,
 705			  struct btrfs_disk_key *disk_key, int slot, int atomic)
 706{
 707	int ret;
 708
 709	ret = tree_mod_log_insert_key_mask(fs_info, eb, slot,
 710					   MOD_LOG_KEY_REPLACE,
 711					   atomic ? GFP_ATOMIC : GFP_NOFS);
 712	BUG_ON(ret < 0);
 713}
 714
 715static void tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
 716				 struct extent_buffer *eb)
 717{
 
 
 718	int i;
 719	int ret;
 720	u32 nritems;
 721
 722	if (tree_mod_dont_log(fs_info, eb))
 723		return;
 
 
 
 724
 725	nritems = btrfs_header_nritems(eb);
 726	for (i = nritems - 1; i >= 0; i--) {
 727		ret = tree_mod_log_insert_key(fs_info, eb, i,
 728					      MOD_LOG_KEY_REMOVE_WHILE_FREEING);
 729		BUG_ON(ret < 0);
 
 
 
 
 
 
 
 730	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 731}
 732
 733static inline void
 734tree_mod_log_set_root_pointer(struct btrfs_root *root,
 735			      struct extent_buffer *new_root_node)
 
 736{
 737	int ret;
 738	tree_mod_log_free_eb(root->fs_info, root->node);
 739	ret = tree_mod_log_insert_root(root->fs_info, root->node,
 740				       new_root_node, GFP_NOFS);
 741	BUG_ON(ret < 0);
 742}
 743
 744/*
 745 * check if the tree block can be shared by multiple trees
 746 */
 747int btrfs_block_can_be_shared(struct btrfs_root *root,
 748			      struct extent_buffer *buf)
 749{
 750	/*
 751	 * Tree blocks not in refernece counted trees and tree roots
 752	 * are never shared. If a block was allocated after the last
 753	 * snapshot and the block was not allocated by tree relocation,
 754	 * we know the block is not shared.
 755	 */
 756	if (root->ref_cows &&
 757	    buf != root->node && buf != root->commit_root &&
 758	    (btrfs_header_generation(buf) <=
 759	     btrfs_root_last_snapshot(&root->root_item) ||
 760	     btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 761		return 1;
 762#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 763	if (root->ref_cows &&
 764	    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 765		return 1;
 766#endif
 767	return 0;
 768}
 769
 770static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 771				       struct btrfs_root *root,
 772				       struct extent_buffer *buf,
 773				       struct extent_buffer *cow,
 774				       int *last_ref)
 775{
 
 776	u64 refs;
 777	u64 owner;
 778	u64 flags;
 779	u64 new_flags = 0;
 780	int ret;
 781
 782	/*
 783	 * Backrefs update rules:
 784	 *
 785	 * Always use full backrefs for extent pointers in tree block
 786	 * allocated by tree relocation.
 787	 *
 788	 * If a shared tree block is no longer referenced by its owner
 789	 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 790	 * use full backrefs for extent pointers in tree block.
 791	 *
 792	 * If a tree block is been relocating
 793	 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
 794	 * use full backrefs for extent pointers in tree block.
 795	 * The reason for this is some operations (such as drop tree)
 796	 * are only allowed for blocks use full backrefs.
 797	 */
 798
 799	if (btrfs_block_can_be_shared(root, buf)) {
 800		ret = btrfs_lookup_extent_info(trans, root, buf->start,
 801					       buf->len, &refs, &flags);
 
 802		if (ret)
 803			return ret;
 804		if (refs == 0) {
 805			ret = -EROFS;
 806			btrfs_std_error(root->fs_info, ret);
 807			return ret;
 808		}
 809	} else {
 810		refs = 1;
 811		if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 812		    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 813			flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
 814		else
 815			flags = 0;
 816	}
 817
 818	owner = btrfs_header_owner(buf);
 819	BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
 820	       !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
 821
 822	if (refs > 1) {
 823		if ((owner == root->root_key.objectid ||
 824		     root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 825		    !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 826			ret = btrfs_inc_ref(trans, root, buf, 1, 1);
 827			BUG_ON(ret); /* -ENOMEM */
 828
 829			if (root->root_key.objectid ==
 830			    BTRFS_TREE_RELOC_OBJECTID) {
 831				ret = btrfs_dec_ref(trans, root, buf, 0, 1);
 832				BUG_ON(ret); /* -ENOMEM */
 833				ret = btrfs_inc_ref(trans, root, cow, 1, 1);
 834				BUG_ON(ret); /* -ENOMEM */
 835			}
 836			new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 837		} else {
 838
 839			if (root->root_key.objectid ==
 840			    BTRFS_TREE_RELOC_OBJECTID)
 841				ret = btrfs_inc_ref(trans, root, cow, 1, 1);
 842			else
 843				ret = btrfs_inc_ref(trans, root, cow, 0, 1);
 844			BUG_ON(ret); /* -ENOMEM */
 845		}
 846		if (new_flags != 0) {
 847			ret = btrfs_set_disk_extent_flags(trans, root,
 
 
 848							  buf->start,
 849							  buf->len,
 850							  new_flags, 0);
 851			if (ret)
 852				return ret;
 853		}
 854	} else {
 855		if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
 856			if (root->root_key.objectid ==
 857			    BTRFS_TREE_RELOC_OBJECTID)
 858				ret = btrfs_inc_ref(trans, root, cow, 1, 1);
 859			else
 860				ret = btrfs_inc_ref(trans, root, cow, 0, 1);
 861			BUG_ON(ret); /* -ENOMEM */
 862			ret = btrfs_dec_ref(trans, root, buf, 1, 1);
 863			BUG_ON(ret); /* -ENOMEM */
 864		}
 865		/*
 866		 * don't log freeing in case we're freeing the root node, this
 867		 * is done by tree_mod_log_set_root_pointer later
 868		 */
 869		if (buf != root->node && btrfs_header_level(buf) != 0)
 870			tree_mod_log_free_eb(root->fs_info, buf);
 871		clean_tree_block(trans, root, buf);
 872		*last_ref = 1;
 873	}
 874	return 0;
 875}
 876
 877/*
 878 * does the dirty work in cow of a single block.  The parent block (if
 879 * supplied) is updated to point to the new cow copy.  The new buffer is marked
 880 * dirty and returned locked.  If you modify the block it needs to be marked
 881 * dirty again.
 882 *
 883 * search_start -- an allocation hint for the new block
 884 *
 885 * empty_size -- a hint that you plan on doing more cow.  This is the size in
 886 * bytes the allocator should try to find free next to the block it returns.
 887 * This is just a hint and may be ignored by the allocator.
 888 */
 889static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 890			     struct btrfs_root *root,
 891			     struct extent_buffer *buf,
 892			     struct extent_buffer *parent, int parent_slot,
 893			     struct extent_buffer **cow_ret,
 894			     u64 search_start, u64 empty_size)
 895{
 
 896	struct btrfs_disk_key disk_key;
 897	struct extent_buffer *cow;
 898	int level, ret;
 899	int last_ref = 0;
 900	int unlock_orig = 0;
 901	u64 parent_start;
 902
 903	if (*cow_ret == buf)
 904		unlock_orig = 1;
 905
 906	btrfs_assert_tree_locked(buf);
 907
 908	WARN_ON(root->ref_cows && trans->transid !=
 909		root->fs_info->running_transaction->transid);
 910	WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 
 911
 912	level = btrfs_header_level(buf);
 913
 914	if (level == 0)
 915		btrfs_item_key(buf, &disk_key, 0);
 916	else
 917		btrfs_node_key(buf, &disk_key, 0);
 918
 919	if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
 920		if (parent)
 921			parent_start = parent->start;
 922		else
 923			parent_start = 0;
 924	} else
 925		parent_start = 0;
 926
 927	cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
 928				     root->root_key.objectid, &disk_key,
 929				     level, search_start, empty_size);
 930	if (IS_ERR(cow))
 931		return PTR_ERR(cow);
 932
 933	/* cow is set to blocking by btrfs_init_new_buffer */
 934
 935	copy_extent_buffer(cow, buf, 0, 0, cow->len);
 936	btrfs_set_header_bytenr(cow, cow->start);
 937	btrfs_set_header_generation(cow, trans->transid);
 938	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 939	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 940				     BTRFS_HEADER_FLAG_RELOC);
 941	if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 942		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 943	else
 944		btrfs_set_header_owner(cow, root->root_key.objectid);
 945
 946	write_extent_buffer(cow, root->fs_info->fsid,
 947			    (unsigned long)btrfs_header_fsid(cow),
 948			    BTRFS_FSID_SIZE);
 949
 950	ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
 951	if (ret) {
 952		btrfs_abort_transaction(trans, root, ret);
 953		return ret;
 954	}
 955
 956	if (root->ref_cows)
 957		btrfs_reloc_cow_block(trans, root, buf, cow);
 
 
 
 
 
 958
 959	if (buf == root->node) {
 960		WARN_ON(parent && parent != buf);
 961		if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 962		    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 963			parent_start = buf->start;
 964		else
 965			parent_start = 0;
 966
 967		extent_buffer_get(cow);
 968		tree_mod_log_set_root_pointer(root, cow);
 969		rcu_assign_pointer(root->node, cow);
 970
 971		btrfs_free_tree_block(trans, root, buf, parent_start,
 972				      last_ref);
 973		free_extent_buffer(buf);
 974		add_root_to_dirty_list(root);
 975	} else {
 976		if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 977			parent_start = parent->start;
 978		else
 979			parent_start = 0;
 980
 981		WARN_ON(trans->transid != btrfs_header_generation(parent));
 982		tree_mod_log_insert_key(root->fs_info, parent, parent_slot,
 983					MOD_LOG_KEY_REPLACE);
 984		btrfs_set_node_blockptr(parent, parent_slot,
 985					cow->start);
 986		btrfs_set_node_ptr_generation(parent, parent_slot,
 987					      trans->transid);
 988		btrfs_mark_buffer_dirty(parent);
 
 
 
 
 
 
 
 989		btrfs_free_tree_block(trans, root, buf, parent_start,
 990				      last_ref);
 991	}
 992	if (unlock_orig)
 993		btrfs_tree_unlock(buf);
 994	free_extent_buffer_stale(buf);
 995	btrfs_mark_buffer_dirty(cow);
 996	*cow_ret = cow;
 997	return 0;
 998}
 999
1000/*
1001 * returns the logical address of the oldest predecessor of the given root.
1002 * entries older than time_seq are ignored.
1003 */
1004static struct tree_mod_elem *
1005__tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info,
1006			   struct btrfs_root *root, u64 time_seq)
1007{
1008	struct tree_mod_elem *tm;
1009	struct tree_mod_elem *found = NULL;
1010	u64 root_logical = root->node->start;
1011	int looped = 0;
1012
1013	if (!time_seq)
1014		return 0;
1015
1016	/*
1017	 * the very last operation that's logged for a root is the replacement
1018	 * operation (if it is replaced at all). this has the index of the *new*
1019	 * root, making it the very first operation that's logged for this root.
 
1020	 */
1021	while (1) {
1022		tm = tree_mod_log_search_oldest(fs_info, root_logical,
1023						time_seq);
1024		if (!looped && !tm)
1025			return 0;
1026		/*
1027		 * if there are no tree operation for the oldest root, we simply
1028		 * return it. this should only happen if that (old) root is at
1029		 * level 0.
1030		 */
1031		if (!tm)
1032			break;
1033
1034		/*
1035		 * if there's an operation that's not a root replacement, we
1036		 * found the oldest version of our root. normally, we'll find a
1037		 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1038		 */
1039		if (tm->op != MOD_LOG_ROOT_REPLACE)
1040			break;
1041
1042		found = tm;
1043		root_logical = tm->old_root.logical;
1044		BUG_ON(root_logical == root->node->start);
1045		looped = 1;
1046	}
1047
1048	/* if there's no old root to return, return what we found instead */
1049	if (!found)
1050		found = tm;
1051
1052	return found;
1053}
1054
1055/*
1056 * tm is a pointer to the first operation to rewind within eb. then, all
1057 * previous operations will be rewinded (until we reach something older than
1058 * time_seq).
1059 */
1060static void
1061__tree_mod_log_rewind(struct extent_buffer *eb, u64 time_seq,
1062		      struct tree_mod_elem *first_tm)
1063{
1064	u32 n;
1065	struct rb_node *next;
1066	struct tree_mod_elem *tm = first_tm;
1067	unsigned long o_dst;
1068	unsigned long o_src;
1069	unsigned long p_size = sizeof(struct btrfs_key_ptr);
1070
1071	n = btrfs_header_nritems(eb);
1072	while (tm && tm->elem.seq >= time_seq) {
 
1073		/*
1074		 * all the operations are recorded with the operator used for
1075		 * the modification. as we're going backwards, we do the
1076		 * opposite of each operation here.
1077		 */
1078		switch (tm->op) {
1079		case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1080			BUG_ON(tm->slot < n);
 
1081		case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1082		case MOD_LOG_KEY_REMOVE:
1083			btrfs_set_node_key(eb, &tm->key, tm->slot);
1084			btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1085			btrfs_set_node_ptr_generation(eb, tm->slot,
1086						      tm->generation);
1087			n++;
1088			break;
1089		case MOD_LOG_KEY_REPLACE:
1090			BUG_ON(tm->slot >= n);
1091			btrfs_set_node_key(eb, &tm->key, tm->slot);
1092			btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1093			btrfs_set_node_ptr_generation(eb, tm->slot,
1094						      tm->generation);
1095			break;
1096		case MOD_LOG_KEY_ADD:
1097			/* if a move operation is needed it's in the log */
1098			n--;
1099			break;
1100		case MOD_LOG_MOVE_KEYS:
1101			o_dst = btrfs_node_key_ptr_offset(tm->slot);
1102			o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1103			memmove_extent_buffer(eb, o_dst, o_src,
1104					      tm->move.nr_items * p_size);
1105			break;
1106		case MOD_LOG_ROOT_REPLACE:
1107			/*
1108			 * this operation is special. for roots, this must be
1109			 * handled explicitly before rewinding.
1110			 * for non-roots, this operation may exist if the node
1111			 * was a root: root A -> child B; then A gets empty and
1112			 * B is promoted to the new root. in the mod log, we'll
1113			 * have a root-replace operation for B, a tree block
1114			 * that is no root. we simply ignore that operation.
1115			 */
1116			break;
1117		}
1118		next = rb_next(&tm->node);
1119		if (!next)
1120			break;
1121		tm = container_of(next, struct tree_mod_elem, node);
1122		if (tm->index != first_tm->index)
1123			break;
1124	}
 
1125	btrfs_set_header_nritems(eb, n);
1126}
1127
 
 
 
 
 
 
 
1128static struct extent_buffer *
1129tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1130		    u64 time_seq)
1131{
1132	struct extent_buffer *eb_rewin;
1133	struct tree_mod_elem *tm;
1134
1135	if (!time_seq)
1136		return eb;
1137
1138	if (btrfs_header_level(eb) == 0)
1139		return eb;
1140
1141	tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1142	if (!tm)
1143		return eb;
1144
 
 
 
1145	if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1146		BUG_ON(tm->slot != 0);
1147		eb_rewin = alloc_dummy_extent_buffer(eb->start,
1148						fs_info->tree_root->nodesize);
1149		BUG_ON(!eb_rewin);
 
 
 
1150		btrfs_set_header_bytenr(eb_rewin, eb->start);
1151		btrfs_set_header_backref_rev(eb_rewin,
1152					     btrfs_header_backref_rev(eb));
1153		btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1154		btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1155	} else {
1156		eb_rewin = btrfs_clone_extent_buffer(eb);
1157		BUG_ON(!eb_rewin);
 
 
 
 
1158	}
1159
1160	extent_buffer_get(eb_rewin);
 
1161	free_extent_buffer(eb);
1162
1163	__tree_mod_log_rewind(eb_rewin, time_seq, tm);
 
 
 
 
1164
1165	return eb_rewin;
1166}
1167
1168/*
1169 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1170 * value. If there are no changes, the current root->root_node is returned. If
1171 * anything changed in between, there's a fresh buffer allocated on which the
1172 * rewind operations are done. In any case, the returned buffer is read locked.
1173 * Returns NULL on error (with no locks held).
1174 */
1175static inline struct extent_buffer *
1176get_old_root(struct btrfs_root *root, u64 time_seq)
1177{
 
1178	struct tree_mod_elem *tm;
1179	struct extent_buffer *eb;
 
 
1180	struct tree_mod_root *old_root = NULL;
1181	u64 old_generation = 0;
1182	u64 logical;
1183
1184	eb = btrfs_read_lock_root_node(root);
1185	tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
1186	if (!tm)
1187		return root->node;
1188
1189	if (tm->op == MOD_LOG_ROOT_REPLACE) {
1190		old_root = &tm->old_root;
1191		old_generation = tm->generation;
1192		logical = old_root->logical;
1193	} else {
1194		logical = root->node->start;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1195	}
1196
1197	tm = tree_mod_log_search(root->fs_info, logical, time_seq);
1198	if (old_root)
1199		eb = alloc_dummy_extent_buffer(logical, root->nodesize);
1200	else
1201		eb = btrfs_clone_extent_buffer(root->node);
1202	btrfs_tree_read_unlock(root->node);
1203	free_extent_buffer(root->node);
1204	if (!eb)
1205		return NULL;
 
1206	btrfs_tree_read_lock(eb);
1207	if (old_root) {
1208		btrfs_set_header_bytenr(eb, eb->start);
1209		btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1210		btrfs_set_header_owner(eb, root->root_key.objectid);
1211		btrfs_set_header_level(eb, old_root->level);
1212		btrfs_set_header_generation(eb, old_generation);
1213	}
1214	if (tm)
1215		__tree_mod_log_rewind(eb, time_seq, tm);
1216	else
1217		WARN_ON(btrfs_header_level(eb) != 0);
1218	extent_buffer_get(eb);
1219
1220	return eb;
1221}
1222
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1223static inline int should_cow_block(struct btrfs_trans_handle *trans,
1224				   struct btrfs_root *root,
1225				   struct extent_buffer *buf)
1226{
 
 
 
1227	/* ensure we can see the force_cow */
1228	smp_rmb();
1229
1230	/*
1231	 * We do not need to cow a block if
1232	 * 1) this block is not created or changed in this transaction;
1233	 * 2) this block does not belong to TREE_RELOC tree;
1234	 * 3) the root is not forced COW.
1235	 *
1236	 * What is forced COW:
1237	 *    when we create snapshot during commiting the transaction,
1238	 *    after we've finished coping src root, we must COW the shared
1239	 *    block to ensure the metadata consistency.
1240	 */
1241	if (btrfs_header_generation(buf) == trans->transid &&
1242	    !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1243	    !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1244	      btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1245	    !root->force_cow)
1246		return 0;
1247	return 1;
1248}
1249
1250/*
1251 * cows a single block, see __btrfs_cow_block for the real work.
1252 * This version of it has extra checks so that a block isn't cow'd more than
1253 * once per transaction, as long as it hasn't been written yet
1254 */
1255noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1256		    struct btrfs_root *root, struct extent_buffer *buf,
1257		    struct extent_buffer *parent, int parent_slot,
1258		    struct extent_buffer **cow_ret)
1259{
 
1260	u64 search_start;
1261	int ret;
1262
1263	if (trans->transaction != root->fs_info->running_transaction) {
1264		printk(KERN_CRIT "trans %llu running %llu\n",
1265		       (unsigned long long)trans->transid,
1266		       (unsigned long long)
1267		       root->fs_info->running_transaction->transid);
1268		WARN_ON(1);
1269	}
1270	if (trans->transid != root->fs_info->generation) {
1271		printk(KERN_CRIT "trans %llu running %llu\n",
1272		       (unsigned long long)trans->transid,
1273		       (unsigned long long)root->fs_info->generation);
1274		WARN_ON(1);
1275	}
1276
1277	if (!should_cow_block(trans, root, buf)) {
 
1278		*cow_ret = buf;
1279		return 0;
1280	}
1281
1282	search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
1283
1284	if (parent)
1285		btrfs_set_lock_blocking(parent);
1286	btrfs_set_lock_blocking(buf);
1287
1288	ret = __btrfs_cow_block(trans, root, buf, parent,
1289				 parent_slot, cow_ret, search_start, 0);
1290
1291	trace_btrfs_cow_block(root, buf, *cow_ret);
1292
1293	return ret;
1294}
1295
1296/*
1297 * helper function for defrag to decide if two blocks pointed to by a
1298 * node are actually close by
1299 */
1300static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1301{
1302	if (blocknr < other && other - (blocknr + blocksize) < 32768)
1303		return 1;
1304	if (blocknr > other && blocknr - (other + blocksize) < 32768)
1305		return 1;
1306	return 0;
1307}
1308
1309/*
1310 * compare two keys in a memcmp fashion
1311 */
1312static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
1313{
1314	struct btrfs_key k1;
1315
1316	btrfs_disk_key_to_cpu(&k1, disk);
1317
1318	return btrfs_comp_cpu_keys(&k1, k2);
1319}
1320
1321/*
1322 * same as comp_keys only with two btrfs_key's
1323 */
1324int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
1325{
1326	if (k1->objectid > k2->objectid)
1327		return 1;
1328	if (k1->objectid < k2->objectid)
1329		return -1;
1330	if (k1->type > k2->type)
1331		return 1;
1332	if (k1->type < k2->type)
1333		return -1;
1334	if (k1->offset > k2->offset)
1335		return 1;
1336	if (k1->offset < k2->offset)
1337		return -1;
1338	return 0;
1339}
1340
1341/*
1342 * this is used by the defrag code to go through all the
1343 * leaves pointed to by a node and reallocate them so that
1344 * disk order is close to key order
1345 */
1346int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1347		       struct btrfs_root *root, struct extent_buffer *parent,
1348		       int start_slot, int cache_only, u64 *last_ret,
1349		       struct btrfs_key *progress)
1350{
 
1351	struct extent_buffer *cur;
1352	u64 blocknr;
1353	u64 gen;
1354	u64 search_start = *last_ret;
1355	u64 last_block = 0;
1356	u64 other;
1357	u32 parent_nritems;
1358	int end_slot;
1359	int i;
1360	int err = 0;
1361	int parent_level;
1362	int uptodate;
1363	u32 blocksize;
1364	int progress_passed = 0;
1365	struct btrfs_disk_key disk_key;
1366
1367	parent_level = btrfs_header_level(parent);
1368	if (cache_only && parent_level != 1)
1369		return 0;
1370
1371	if (trans->transaction != root->fs_info->running_transaction)
1372		WARN_ON(1);
1373	if (trans->transid != root->fs_info->generation)
1374		WARN_ON(1);
1375
1376	parent_nritems = btrfs_header_nritems(parent);
1377	blocksize = btrfs_level_size(root, parent_level - 1);
1378	end_slot = parent_nritems;
1379
1380	if (parent_nritems == 1)
1381		return 0;
1382
1383	btrfs_set_lock_blocking(parent);
1384
1385	for (i = start_slot; i < end_slot; i++) {
1386		int close = 1;
1387
1388		btrfs_node_key(parent, &disk_key, i);
1389		if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1390			continue;
1391
1392		progress_passed = 1;
1393		blocknr = btrfs_node_blockptr(parent, i);
1394		gen = btrfs_node_ptr_generation(parent, i);
1395		if (last_block == 0)
1396			last_block = blocknr;
1397
1398		if (i > 0) {
1399			other = btrfs_node_blockptr(parent, i - 1);
1400			close = close_blocks(blocknr, other, blocksize);
1401		}
1402		if (!close && i < end_slot - 2) {
1403			other = btrfs_node_blockptr(parent, i + 1);
1404			close = close_blocks(blocknr, other, blocksize);
1405		}
1406		if (close) {
1407			last_block = blocknr;
1408			continue;
1409		}
1410
1411		cur = btrfs_find_tree_block(root, blocknr, blocksize);
1412		if (cur)
1413			uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1414		else
1415			uptodate = 0;
1416		if (!cur || !uptodate) {
1417			if (cache_only) {
1418				free_extent_buffer(cur);
1419				continue;
1420			}
1421			if (!cur) {
1422				cur = read_tree_block(root, blocknr,
1423							 blocksize, gen);
1424				if (!cur)
 
 
1425					return -EIO;
 
1426			} else if (!uptodate) {
1427				err = btrfs_read_buffer(cur, gen);
1428				if (err) {
1429					free_extent_buffer(cur);
1430					return err;
1431				}
1432			}
1433		}
1434		if (search_start == 0)
1435			search_start = last_block;
1436
1437		btrfs_tree_lock(cur);
1438		btrfs_set_lock_blocking(cur);
1439		err = __btrfs_cow_block(trans, root, cur, parent, i,
1440					&cur, search_start,
1441					min(16 * blocksize,
1442					    (end_slot - i) * blocksize));
1443		if (err) {
1444			btrfs_tree_unlock(cur);
1445			free_extent_buffer(cur);
1446			break;
1447		}
1448		search_start = cur->start;
1449		last_block = cur->start;
1450		*last_ret = search_start;
1451		btrfs_tree_unlock(cur);
1452		free_extent_buffer(cur);
1453	}
1454	return err;
1455}
1456
1457/*
1458 * The leaf data grows from end-to-front in the node.
1459 * this returns the address of the start of the last item,
1460 * which is the stop of the leaf data stack
1461 */
1462static inline unsigned int leaf_data_end(struct btrfs_root *root,
1463					 struct extent_buffer *leaf)
1464{
1465	u32 nr = btrfs_header_nritems(leaf);
1466	if (nr == 0)
1467		return BTRFS_LEAF_DATA_SIZE(root);
1468	return btrfs_item_offset_nr(leaf, nr - 1);
1469}
1470
1471
1472/*
1473 * search for key in the extent_buffer.  The items start at offset p,
1474 * and they are item_size apart.  There are 'max' items in p.
1475 *
1476 * the slot in the array is returned via slot, and it points to
1477 * the place where you would insert key if it is not found in
1478 * the array.
1479 *
1480 * slot may point to max if the key is bigger than all of the keys
1481 */
1482static noinline int generic_bin_search(struct extent_buffer *eb,
1483				       unsigned long p,
1484				       int item_size, struct btrfs_key *key,
1485				       int max, int *slot)
1486{
1487	int low = 0;
1488	int high = max;
1489	int mid;
1490	int ret;
1491	struct btrfs_disk_key *tmp = NULL;
1492	struct btrfs_disk_key unaligned;
1493	unsigned long offset;
1494	char *kaddr = NULL;
1495	unsigned long map_start = 0;
1496	unsigned long map_len = 0;
1497	int err;
1498
 
 
 
 
 
 
 
 
1499	while (low < high) {
1500		mid = (low + high) / 2;
1501		offset = p + mid * item_size;
1502
1503		if (!kaddr || offset < map_start ||
1504		    (offset + sizeof(struct btrfs_disk_key)) >
1505		    map_start + map_len) {
1506
1507			err = map_private_extent_buffer(eb, offset,
1508						sizeof(struct btrfs_disk_key),
1509						&kaddr, &map_start, &map_len);
1510
1511			if (!err) {
1512				tmp = (struct btrfs_disk_key *)(kaddr + offset -
1513							map_start);
1514			} else {
1515				read_extent_buffer(eb, &unaligned,
1516						   offset, sizeof(unaligned));
1517				tmp = &unaligned;
 
 
1518			}
1519
1520		} else {
1521			tmp = (struct btrfs_disk_key *)(kaddr + offset -
1522							map_start);
1523		}
1524		ret = comp_keys(tmp, key);
1525
1526		if (ret < 0)
1527			low = mid + 1;
1528		else if (ret > 0)
1529			high = mid;
1530		else {
1531			*slot = mid;
1532			return 0;
1533		}
1534	}
1535	*slot = low;
1536	return 1;
1537}
1538
1539/*
1540 * simple bin_search frontend that does the right thing for
1541 * leaves vs nodes
1542 */
1543static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1544		      int level, int *slot)
1545{
1546	if (level == 0)
1547		return generic_bin_search(eb,
1548					  offsetof(struct btrfs_leaf, items),
1549					  sizeof(struct btrfs_item),
1550					  key, btrfs_header_nritems(eb),
1551					  slot);
1552	else
1553		return generic_bin_search(eb,
1554					  offsetof(struct btrfs_node, ptrs),
1555					  sizeof(struct btrfs_key_ptr),
1556					  key, btrfs_header_nritems(eb),
1557					  slot);
1558}
1559
1560int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1561		     int level, int *slot)
1562{
1563	return bin_search(eb, key, level, slot);
1564}
1565
1566static void root_add_used(struct btrfs_root *root, u32 size)
1567{
1568	spin_lock(&root->accounting_lock);
1569	btrfs_set_root_used(&root->root_item,
1570			    btrfs_root_used(&root->root_item) + size);
1571	spin_unlock(&root->accounting_lock);
1572}
1573
1574static void root_sub_used(struct btrfs_root *root, u32 size)
1575{
1576	spin_lock(&root->accounting_lock);
1577	btrfs_set_root_used(&root->root_item,
1578			    btrfs_root_used(&root->root_item) - size);
1579	spin_unlock(&root->accounting_lock);
1580}
1581
1582/* given a node and slot number, this reads the blocks it points to.  The
1583 * extent buffer is returned with a reference taken (but unlocked).
1584 * NULL is returned on error.
1585 */
1586static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
1587				   struct extent_buffer *parent, int slot)
 
1588{
1589	int level = btrfs_header_level(parent);
1590	if (slot < 0)
1591		return NULL;
1592	if (slot >= btrfs_header_nritems(parent))
1593		return NULL;
1594
1595	BUG_ON(level == 0);
1596
1597	return read_tree_block(root, btrfs_node_blockptr(parent, slot),
1598		       btrfs_level_size(root, level - 1),
1599		       btrfs_node_ptr_generation(parent, slot));
 
 
 
 
 
1600}
1601
1602/*
1603 * node level balancing, used to make sure nodes are in proper order for
1604 * item deletion.  We balance from the top down, so we have to make sure
1605 * that a deletion won't leave an node completely empty later on.
1606 */
1607static noinline int balance_level(struct btrfs_trans_handle *trans,
1608			 struct btrfs_root *root,
1609			 struct btrfs_path *path, int level)
1610{
 
1611	struct extent_buffer *right = NULL;
1612	struct extent_buffer *mid;
1613	struct extent_buffer *left = NULL;
1614	struct extent_buffer *parent = NULL;
1615	int ret = 0;
1616	int wret;
1617	int pslot;
1618	int orig_slot = path->slots[level];
1619	u64 orig_ptr;
1620
1621	if (level == 0)
1622		return 0;
1623
1624	mid = path->nodes[level];
1625
1626	WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1627		path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1628	WARN_ON(btrfs_header_generation(mid) != trans->transid);
1629
1630	orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1631
1632	if (level < BTRFS_MAX_LEVEL - 1) {
1633		parent = path->nodes[level + 1];
1634		pslot = path->slots[level + 1];
1635	}
1636
1637	/*
1638	 * deal with the case where there is only one pointer in the root
1639	 * by promoting the node below to a root
1640	 */
1641	if (!parent) {
1642		struct extent_buffer *child;
1643
1644		if (btrfs_header_nritems(mid) != 1)
1645			return 0;
1646
1647		/* promote the child to a root */
1648		child = read_node_slot(root, mid, 0);
1649		if (!child) {
1650			ret = -EROFS;
1651			btrfs_std_error(root->fs_info, ret);
1652			goto enospc;
1653		}
1654
1655		btrfs_tree_lock(child);
1656		btrfs_set_lock_blocking(child);
1657		ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1658		if (ret) {
1659			btrfs_tree_unlock(child);
1660			free_extent_buffer(child);
1661			goto enospc;
1662		}
1663
1664		tree_mod_log_set_root_pointer(root, child);
1665		rcu_assign_pointer(root->node, child);
1666
1667		add_root_to_dirty_list(root);
1668		btrfs_tree_unlock(child);
1669
1670		path->locks[level] = 0;
1671		path->nodes[level] = NULL;
1672		clean_tree_block(trans, root, mid);
1673		btrfs_tree_unlock(mid);
1674		/* once for the path */
1675		free_extent_buffer(mid);
1676
1677		root_sub_used(root, mid->len);
1678		btrfs_free_tree_block(trans, root, mid, 0, 1);
1679		/* once for the root ptr */
1680		free_extent_buffer_stale(mid);
1681		return 0;
1682	}
1683	if (btrfs_header_nritems(mid) >
1684	    BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
1685		return 0;
1686
1687	left = read_node_slot(root, parent, pslot - 1);
 
 
 
1688	if (left) {
1689		btrfs_tree_lock(left);
1690		btrfs_set_lock_blocking(left);
1691		wret = btrfs_cow_block(trans, root, left,
1692				       parent, pslot - 1, &left);
1693		if (wret) {
1694			ret = wret;
1695			goto enospc;
1696		}
1697	}
1698	right = read_node_slot(root, parent, pslot + 1);
 
 
 
 
1699	if (right) {
1700		btrfs_tree_lock(right);
1701		btrfs_set_lock_blocking(right);
1702		wret = btrfs_cow_block(trans, root, right,
1703				       parent, pslot + 1, &right);
1704		if (wret) {
1705			ret = wret;
1706			goto enospc;
1707		}
1708	}
1709
1710	/* first, try to make some room in the middle buffer */
1711	if (left) {
1712		orig_slot += btrfs_header_nritems(left);
1713		wret = push_node_left(trans, root, left, mid, 1);
1714		if (wret < 0)
1715			ret = wret;
1716	}
1717
1718	/*
1719	 * then try to empty the right most buffer into the middle
1720	 */
1721	if (right) {
1722		wret = push_node_left(trans, root, mid, right, 1);
1723		if (wret < 0 && wret != -ENOSPC)
1724			ret = wret;
1725		if (btrfs_header_nritems(right) == 0) {
1726			clean_tree_block(trans, root, right);
1727			btrfs_tree_unlock(right);
1728			del_ptr(trans, root, path, level + 1, pslot + 1, 1);
1729			root_sub_used(root, right->len);
1730			btrfs_free_tree_block(trans, root, right, 0, 1);
1731			free_extent_buffer_stale(right);
1732			right = NULL;
1733		} else {
1734			struct btrfs_disk_key right_key;
1735			btrfs_node_key(right, &right_key, 0);
1736			tree_mod_log_set_node_key(root->fs_info, parent,
1737						  &right_key, pslot + 1, 0);
1738			btrfs_set_node_key(parent, &right_key, pslot + 1);
1739			btrfs_mark_buffer_dirty(parent);
1740		}
1741	}
1742	if (btrfs_header_nritems(mid) == 1) {
1743		/*
1744		 * we're not allowed to leave a node with one item in the
1745		 * tree during a delete.  A deletion from lower in the tree
1746		 * could try to delete the only pointer in this node.
1747		 * So, pull some keys from the left.
1748		 * There has to be a left pointer at this point because
1749		 * otherwise we would have pulled some pointers from the
1750		 * right
1751		 */
1752		if (!left) {
1753			ret = -EROFS;
1754			btrfs_std_error(root->fs_info, ret);
1755			goto enospc;
1756		}
1757		wret = balance_node_right(trans, root, mid, left);
1758		if (wret < 0) {
1759			ret = wret;
1760			goto enospc;
1761		}
1762		if (wret == 1) {
1763			wret = push_node_left(trans, root, left, mid, 1);
1764			if (wret < 0)
1765				ret = wret;
1766		}
1767		BUG_ON(wret == 1);
1768	}
1769	if (btrfs_header_nritems(mid) == 0) {
1770		clean_tree_block(trans, root, mid);
1771		btrfs_tree_unlock(mid);
1772		del_ptr(trans, root, path, level + 1, pslot, 1);
1773		root_sub_used(root, mid->len);
1774		btrfs_free_tree_block(trans, root, mid, 0, 1);
1775		free_extent_buffer_stale(mid);
1776		mid = NULL;
1777	} else {
1778		/* update the parent key to reflect our changes */
1779		struct btrfs_disk_key mid_key;
1780		btrfs_node_key(mid, &mid_key, 0);
1781		tree_mod_log_set_node_key(root->fs_info, parent, &mid_key,
1782					  pslot, 0);
1783		btrfs_set_node_key(parent, &mid_key, pslot);
1784		btrfs_mark_buffer_dirty(parent);
1785	}
1786
1787	/* update the path */
1788	if (left) {
1789		if (btrfs_header_nritems(left) > orig_slot) {
1790			extent_buffer_get(left);
1791			/* left was locked after cow */
1792			path->nodes[level] = left;
1793			path->slots[level + 1] -= 1;
1794			path->slots[level] = orig_slot;
1795			if (mid) {
1796				btrfs_tree_unlock(mid);
1797				free_extent_buffer(mid);
1798			}
1799		} else {
1800			orig_slot -= btrfs_header_nritems(left);
1801			path->slots[level] = orig_slot;
1802		}
1803	}
1804	/* double check we haven't messed things up */
1805	if (orig_ptr !=
1806	    btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1807		BUG();
1808enospc:
1809	if (right) {
1810		btrfs_tree_unlock(right);
1811		free_extent_buffer(right);
1812	}
1813	if (left) {
1814		if (path->nodes[level] != left)
1815			btrfs_tree_unlock(left);
1816		free_extent_buffer(left);
1817	}
1818	return ret;
1819}
1820
1821/* Node balancing for insertion.  Here we only split or push nodes around
1822 * when they are completely full.  This is also done top down, so we
1823 * have to be pessimistic.
1824 */
1825static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1826					  struct btrfs_root *root,
1827					  struct btrfs_path *path, int level)
1828{
 
1829	struct extent_buffer *right = NULL;
1830	struct extent_buffer *mid;
1831	struct extent_buffer *left = NULL;
1832	struct extent_buffer *parent = NULL;
1833	int ret = 0;
1834	int wret;
1835	int pslot;
1836	int orig_slot = path->slots[level];
1837
1838	if (level == 0)
1839		return 1;
1840
1841	mid = path->nodes[level];
1842	WARN_ON(btrfs_header_generation(mid) != trans->transid);
1843
1844	if (level < BTRFS_MAX_LEVEL - 1) {
1845		parent = path->nodes[level + 1];
1846		pslot = path->slots[level + 1];
1847	}
1848
1849	if (!parent)
1850		return 1;
1851
1852	left = read_node_slot(root, parent, pslot - 1);
 
 
1853
1854	/* first, try to make some room in the middle buffer */
1855	if (left) {
1856		u32 left_nr;
1857
1858		btrfs_tree_lock(left);
1859		btrfs_set_lock_blocking(left);
1860
1861		left_nr = btrfs_header_nritems(left);
1862		if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1863			wret = 1;
1864		} else {
1865			ret = btrfs_cow_block(trans, root, left, parent,
1866					      pslot - 1, &left);
1867			if (ret)
1868				wret = 1;
1869			else {
1870				wret = push_node_left(trans, root,
1871						      left, mid, 0);
1872			}
1873		}
1874		if (wret < 0)
1875			ret = wret;
1876		if (wret == 0) {
1877			struct btrfs_disk_key disk_key;
1878			orig_slot += left_nr;
1879			btrfs_node_key(mid, &disk_key, 0);
1880			tree_mod_log_set_node_key(root->fs_info, parent,
1881						  &disk_key, pslot, 0);
1882			btrfs_set_node_key(parent, &disk_key, pslot);
1883			btrfs_mark_buffer_dirty(parent);
1884			if (btrfs_header_nritems(left) > orig_slot) {
1885				path->nodes[level] = left;
1886				path->slots[level + 1] -= 1;
1887				path->slots[level] = orig_slot;
1888				btrfs_tree_unlock(mid);
1889				free_extent_buffer(mid);
1890			} else {
1891				orig_slot -=
1892					btrfs_header_nritems(left);
1893				path->slots[level] = orig_slot;
1894				btrfs_tree_unlock(left);
1895				free_extent_buffer(left);
1896			}
1897			return 0;
1898		}
1899		btrfs_tree_unlock(left);
1900		free_extent_buffer(left);
1901	}
1902	right = read_node_slot(root, parent, pslot + 1);
 
 
1903
1904	/*
1905	 * then try to empty the right most buffer into the middle
1906	 */
1907	if (right) {
1908		u32 right_nr;
1909
1910		btrfs_tree_lock(right);
1911		btrfs_set_lock_blocking(right);
1912
1913		right_nr = btrfs_header_nritems(right);
1914		if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1915			wret = 1;
1916		} else {
1917			ret = btrfs_cow_block(trans, root, right,
1918					      parent, pslot + 1,
1919					      &right);
1920			if (ret)
1921				wret = 1;
1922			else {
1923				wret = balance_node_right(trans, root,
1924							  right, mid);
1925			}
1926		}
1927		if (wret < 0)
1928			ret = wret;
1929		if (wret == 0) {
1930			struct btrfs_disk_key disk_key;
1931
1932			btrfs_node_key(right, &disk_key, 0);
1933			tree_mod_log_set_node_key(root->fs_info, parent,
1934						  &disk_key, pslot + 1, 0);
1935			btrfs_set_node_key(parent, &disk_key, pslot + 1);
1936			btrfs_mark_buffer_dirty(parent);
1937
1938			if (btrfs_header_nritems(mid) <= orig_slot) {
1939				path->nodes[level] = right;
1940				path->slots[level + 1] += 1;
1941				path->slots[level] = orig_slot -
1942					btrfs_header_nritems(mid);
1943				btrfs_tree_unlock(mid);
1944				free_extent_buffer(mid);
1945			} else {
1946				btrfs_tree_unlock(right);
1947				free_extent_buffer(right);
1948			}
1949			return 0;
1950		}
1951		btrfs_tree_unlock(right);
1952		free_extent_buffer(right);
1953	}
1954	return 1;
1955}
1956
1957/*
1958 * readahead one full node of leaves, finding things that are close
1959 * to the block in 'slot', and triggering ra on them.
1960 */
1961static void reada_for_search(struct btrfs_root *root,
1962			     struct btrfs_path *path,
1963			     int level, int slot, u64 objectid)
1964{
1965	struct extent_buffer *node;
1966	struct btrfs_disk_key disk_key;
1967	u32 nritems;
1968	u64 search;
1969	u64 target;
1970	u64 nread = 0;
1971	u64 gen;
1972	int direction = path->reada;
1973	struct extent_buffer *eb;
1974	u32 nr;
1975	u32 blocksize;
1976	u32 nscan = 0;
1977
1978	if (level != 1)
1979		return;
1980
1981	if (!path->nodes[level])
1982		return;
1983
1984	node = path->nodes[level];
1985
1986	search = btrfs_node_blockptr(node, slot);
1987	blocksize = btrfs_level_size(root, level - 1);
1988	eb = btrfs_find_tree_block(root, search, blocksize);
1989	if (eb) {
1990		free_extent_buffer(eb);
1991		return;
1992	}
1993
1994	target = search;
1995
1996	nritems = btrfs_header_nritems(node);
1997	nr = slot;
1998
1999	while (1) {
2000		if (direction < 0) {
2001			if (nr == 0)
2002				break;
2003			nr--;
2004		} else if (direction > 0) {
2005			nr++;
2006			if (nr >= nritems)
2007				break;
2008		}
2009		if (path->reada < 0 && objectid) {
2010			btrfs_node_key(node, &disk_key, nr);
2011			if (btrfs_disk_key_objectid(&disk_key) != objectid)
2012				break;
2013		}
2014		search = btrfs_node_blockptr(node, nr);
2015		if ((search <= target && target - search <= 65536) ||
2016		    (search > target && search - target <= 65536)) {
2017			gen = btrfs_node_ptr_generation(node, nr);
2018			readahead_tree_block(root, search, blocksize, gen);
2019			nread += blocksize;
2020		}
2021		nscan++;
2022		if ((nread > 65536 || nscan > 32))
2023			break;
2024	}
2025}
2026
2027/*
2028 * returns -EAGAIN if it had to drop the path, or zero if everything was in
2029 * cache
2030 */
2031static noinline int reada_for_balance(struct btrfs_root *root,
2032				      struct btrfs_path *path, int level)
2033{
2034	int slot;
2035	int nritems;
2036	struct extent_buffer *parent;
2037	struct extent_buffer *eb;
2038	u64 gen;
2039	u64 block1 = 0;
2040	u64 block2 = 0;
2041	int ret = 0;
2042	int blocksize;
2043
2044	parent = path->nodes[level + 1];
2045	if (!parent)
2046		return 0;
2047
2048	nritems = btrfs_header_nritems(parent);
2049	slot = path->slots[level + 1];
2050	blocksize = btrfs_level_size(root, level);
2051
2052	if (slot > 0) {
2053		block1 = btrfs_node_blockptr(parent, slot - 1);
2054		gen = btrfs_node_ptr_generation(parent, slot - 1);
2055		eb = btrfs_find_tree_block(root, block1, blocksize);
2056		/*
2057		 * if we get -eagain from btrfs_buffer_uptodate, we
2058		 * don't want to return eagain here.  That will loop
2059		 * forever
2060		 */
2061		if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2062			block1 = 0;
2063		free_extent_buffer(eb);
2064	}
2065	if (slot + 1 < nritems) {
2066		block2 = btrfs_node_blockptr(parent, slot + 1);
2067		gen = btrfs_node_ptr_generation(parent, slot + 1);
2068		eb = btrfs_find_tree_block(root, block2, blocksize);
2069		if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2070			block2 = 0;
2071		free_extent_buffer(eb);
2072	}
2073	if (block1 || block2) {
2074		ret = -EAGAIN;
2075
2076		/* release the whole path */
2077		btrfs_release_path(path);
2078
2079		/* read the blocks */
2080		if (block1)
2081			readahead_tree_block(root, block1, blocksize, 0);
2082		if (block2)
2083			readahead_tree_block(root, block2, blocksize, 0);
2084
2085		if (block1) {
2086			eb = read_tree_block(root, block1, blocksize, 0);
2087			free_extent_buffer(eb);
2088		}
2089		if (block2) {
2090			eb = read_tree_block(root, block2, blocksize, 0);
2091			free_extent_buffer(eb);
2092		}
2093	}
2094	return ret;
2095}
2096
2097
2098/*
2099 * when we walk down the tree, it is usually safe to unlock the higher layers
2100 * in the tree.  The exceptions are when our path goes through slot 0, because
2101 * operations on the tree might require changing key pointers higher up in the
2102 * tree.
2103 *
2104 * callers might also have set path->keep_locks, which tells this code to keep
2105 * the lock if the path points to the last slot in the block.  This is part of
2106 * walking through the tree, and selecting the next slot in the higher block.
2107 *
2108 * lowest_unlock sets the lowest level in the tree we're allowed to unlock.  so
2109 * if lowest_unlock is 1, level 0 won't be unlocked
2110 */
2111static noinline void unlock_up(struct btrfs_path *path, int level,
2112			       int lowest_unlock, int min_write_lock_level,
2113			       int *write_lock_level)
2114{
2115	int i;
2116	int skip_level = level;
2117	int no_skips = 0;
2118	struct extent_buffer *t;
2119
2120	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2121		if (!path->nodes[i])
2122			break;
2123		if (!path->locks[i])
2124			break;
2125		if (!no_skips && path->slots[i] == 0) {
2126			skip_level = i + 1;
2127			continue;
2128		}
2129		if (!no_skips && path->keep_locks) {
2130			u32 nritems;
2131			t = path->nodes[i];
2132			nritems = btrfs_header_nritems(t);
2133			if (nritems < 1 || path->slots[i] >= nritems - 1) {
2134				skip_level = i + 1;
2135				continue;
2136			}
2137		}
2138		if (skip_level < i && i >= lowest_unlock)
2139			no_skips = 1;
2140
2141		t = path->nodes[i];
2142		if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
2143			btrfs_tree_unlock_rw(t, path->locks[i]);
2144			path->locks[i] = 0;
2145			if (write_lock_level &&
2146			    i > min_write_lock_level &&
2147			    i <= *write_lock_level) {
2148				*write_lock_level = i - 1;
2149			}
2150		}
2151	}
2152}
2153
2154/*
2155 * This releases any locks held in the path starting at level and
2156 * going all the way up to the root.
2157 *
2158 * btrfs_search_slot will keep the lock held on higher nodes in a few
2159 * corner cases, such as COW of the block at slot zero in the node.  This
2160 * ignores those rules, and it should only be called when there are no
2161 * more updates to be done higher up in the tree.
2162 */
2163noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2164{
2165	int i;
2166
2167	if (path->keep_locks)
2168		return;
2169
2170	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2171		if (!path->nodes[i])
2172			continue;
2173		if (!path->locks[i])
2174			continue;
2175		btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2176		path->locks[i] = 0;
2177	}
2178}
2179
2180/*
2181 * helper function for btrfs_search_slot.  The goal is to find a block
2182 * in cache without setting the path to blocking.  If we find the block
2183 * we return zero and the path is unchanged.
2184 *
2185 * If we can't find the block, we set the path blocking and do some
2186 * reada.  -EAGAIN is returned and the search must be repeated.
2187 */
2188static int
2189read_block_for_search(struct btrfs_trans_handle *trans,
2190		       struct btrfs_root *root, struct btrfs_path *p,
2191		       struct extent_buffer **eb_ret, int level, int slot,
2192		       struct btrfs_key *key, u64 time_seq)
2193{
 
2194	u64 blocknr;
2195	u64 gen;
2196	u32 blocksize;
2197	struct extent_buffer *b = *eb_ret;
2198	struct extent_buffer *tmp;
2199	int ret;
2200
2201	blocknr = btrfs_node_blockptr(b, slot);
2202	gen = btrfs_node_ptr_generation(b, slot);
2203	blocksize = btrfs_level_size(root, level - 1);
2204
2205	tmp = btrfs_find_tree_block(root, blocknr, blocksize);
2206	if (tmp) {
2207		/* first we do an atomic uptodate check */
2208		if (btrfs_buffer_uptodate(tmp, 0, 1) > 0) {
2209			if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2210				/*
2211				 * we found an up to date block without
2212				 * sleeping, return
2213				 * right away
2214				 */
2215				*eb_ret = tmp;
2216				return 0;
2217			}
2218			/* the pages were up to date, but we failed
2219			 * the generation number check.  Do a full
2220			 * read for the generation number that is correct.
2221			 * We must do this without dropping locks so
2222			 * we can trust our generation number
2223			 */
2224			free_extent_buffer(tmp);
2225			btrfs_set_path_blocking(p);
2226
2227			/* now we're allowed to do a blocking uptodate check */
2228			tmp = read_tree_block(root, blocknr, blocksize, gen);
2229			if (tmp && btrfs_buffer_uptodate(tmp, gen, 0) > 0) {
2230				*eb_ret = tmp;
2231				return 0;
2232			}
2233			free_extent_buffer(tmp);
2234			btrfs_release_path(p);
2235			return -EIO;
 
 
 
 
2236		}
 
 
 
2237	}
2238
2239	/*
2240	 * reduce lock contention at high levels
2241	 * of the btree by dropping locks before
2242	 * we read.  Don't release the lock on the current
2243	 * level because we need to walk this node to figure
2244	 * out which blocks to read.
2245	 */
2246	btrfs_unlock_up_safe(p, level + 1);
2247	btrfs_set_path_blocking(p);
2248
2249	free_extent_buffer(tmp);
2250	if (p->reada)
2251		reada_for_search(root, p, level, slot, key->objectid);
2252
2253	btrfs_release_path(p);
2254
2255	ret = -EAGAIN;
2256	tmp = read_tree_block(root, blocknr, blocksize, 0);
2257	if (tmp) {
2258		/*
2259		 * If the read above didn't mark this buffer up to date,
2260		 * it will never end up being up to date.  Set ret to EIO now
2261		 * and give up so that our caller doesn't loop forever
2262		 * on our EAGAINs.
2263		 */
2264		if (!btrfs_buffer_uptodate(tmp, 0, 0))
2265			ret = -EIO;
2266		free_extent_buffer(tmp);
 
 
2267	}
2268	return ret;
2269}
2270
2271/*
2272 * helper function for btrfs_search_slot.  This does all of the checks
2273 * for node-level blocks and does any balancing required based on
2274 * the ins_len.
2275 *
2276 * If no extra work was required, zero is returned.  If we had to
2277 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2278 * start over
2279 */
2280static int
2281setup_nodes_for_search(struct btrfs_trans_handle *trans,
2282		       struct btrfs_root *root, struct btrfs_path *p,
2283		       struct extent_buffer *b, int level, int ins_len,
2284		       int *write_lock_level)
2285{
 
2286	int ret;
 
2287	if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2288	    BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
2289		int sret;
2290
2291		if (*write_lock_level < level + 1) {
2292			*write_lock_level = level + 1;
2293			btrfs_release_path(p);
2294			goto again;
2295		}
2296
2297		sret = reada_for_balance(root, p, level);
2298		if (sret)
2299			goto again;
2300
2301		btrfs_set_path_blocking(p);
 
2302		sret = split_node(trans, root, p, level);
2303		btrfs_clear_path_blocking(p, NULL, 0);
2304
2305		BUG_ON(sret > 0);
2306		if (sret) {
2307			ret = sret;
2308			goto done;
2309		}
2310		b = p->nodes[level];
2311	} else if (ins_len < 0 && btrfs_header_nritems(b) <
2312		   BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
2313		int sret;
2314
2315		if (*write_lock_level < level + 1) {
2316			*write_lock_level = level + 1;
2317			btrfs_release_path(p);
2318			goto again;
2319		}
2320
2321		sret = reada_for_balance(root, p, level);
2322		if (sret)
2323			goto again;
2324
2325		btrfs_set_path_blocking(p);
 
2326		sret = balance_level(trans, root, p, level);
2327		btrfs_clear_path_blocking(p, NULL, 0);
2328
2329		if (sret) {
2330			ret = sret;
2331			goto done;
2332		}
2333		b = p->nodes[level];
2334		if (!b) {
2335			btrfs_release_path(p);
2336			goto again;
2337		}
2338		BUG_ON(btrfs_header_nritems(b) == 1);
2339	}
2340	return 0;
2341
2342again:
2343	ret = -EAGAIN;
2344done:
2345	return ret;
2346}
2347
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2348/*
2349 * look for key in the tree.  path is filled in with nodes along the way
2350 * if key is found, we return zero and you can find the item in the leaf
2351 * level of the path (level 0)
2352 *
2353 * If the key isn't found, the path points to the slot where it should
2354 * be inserted, and 1 is returned.  If there are other errors during the
2355 * search a negative error number is returned.
2356 *
2357 * if ins_len > 0, nodes and leaves will be split as we walk down the
2358 * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
2359 * possible)
2360 */
2361int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
2362		      *root, struct btrfs_key *key, struct btrfs_path *p, int
2363		      ins_len, int cow)
2364{
 
2365	struct extent_buffer *b;
2366	int slot;
2367	int ret;
2368	int err;
2369	int level;
2370	int lowest_unlock = 1;
2371	int root_lock;
2372	/* everything at write_lock_level or lower must be write locked */
2373	int write_lock_level = 0;
2374	u8 lowest_level = 0;
2375	int min_write_lock_level;
 
2376
2377	lowest_level = p->lowest_level;
2378	WARN_ON(lowest_level && ins_len > 0);
2379	WARN_ON(p->nodes[0] != NULL);
 
2380
2381	if (ins_len < 0) {
2382		lowest_unlock = 2;
2383
2384		/* when we are removing items, we might have to go up to level
2385		 * two as we update tree pointers  Make sure we keep write
2386		 * for those levels as well
2387		 */
2388		write_lock_level = 2;
2389	} else if (ins_len > 0) {
2390		/*
2391		 * for inserting items, make sure we have a write lock on
2392		 * level 1 so we can update keys
2393		 */
2394		write_lock_level = 1;
2395	}
2396
2397	if (!cow)
2398		write_lock_level = -1;
2399
2400	if (cow && (p->keep_locks || p->lowest_level))
2401		write_lock_level = BTRFS_MAX_LEVEL;
2402
2403	min_write_lock_level = write_lock_level;
2404
2405again:
 
2406	/*
2407	 * we try very hard to do read locks on the root
2408	 */
2409	root_lock = BTRFS_READ_LOCK;
2410	level = 0;
2411	if (p->search_commit_root) {
2412		/*
2413		 * the commit roots are read only
2414		 * so we always do read locks
2415		 */
 
 
2416		b = root->commit_root;
2417		extent_buffer_get(b);
2418		level = btrfs_header_level(b);
 
 
2419		if (!p->skip_locking)
2420			btrfs_tree_read_lock(b);
2421	} else {
2422		if (p->skip_locking) {
2423			b = btrfs_root_node(root);
2424			level = btrfs_header_level(b);
2425		} else {
2426			/* we don't know the level of the root node
2427			 * until we actually have it read locked
2428			 */
2429			b = btrfs_read_lock_root_node(root);
2430			level = btrfs_header_level(b);
2431			if (level <= write_lock_level) {
2432				/* whoops, must trade for write lock */
2433				btrfs_tree_read_unlock(b);
2434				free_extent_buffer(b);
2435				b = btrfs_lock_root_node(root);
2436				root_lock = BTRFS_WRITE_LOCK;
2437
2438				/* the level might have changed, check again */
2439				level = btrfs_header_level(b);
2440			}
2441		}
2442	}
2443	p->nodes[level] = b;
2444	if (!p->skip_locking)
2445		p->locks[level] = root_lock;
2446
2447	while (b) {
2448		level = btrfs_header_level(b);
2449
2450		/*
2451		 * setup the path here so we can release it under lock
2452		 * contention with the cow code
2453		 */
2454		if (cow) {
2455			/*
2456			 * if we don't really need to cow this block
2457			 * then we don't want to set the path blocking,
2458			 * so we test it here
2459			 */
2460			if (!should_cow_block(trans, root, b))
 
2461				goto cow_done;
2462
2463			btrfs_set_path_blocking(p);
2464
2465			/*
2466			 * must have write locks on this node and the
2467			 * parent
2468			 */
2469			if (level + 1 > write_lock_level) {
 
 
 
2470				write_lock_level = level + 1;
2471				btrfs_release_path(p);
2472				goto again;
2473			}
2474
 
2475			err = btrfs_cow_block(trans, root, b,
2476					      p->nodes[level + 1],
2477					      p->slots[level + 1], &b);
2478			if (err) {
2479				ret = err;
2480				goto done;
2481			}
2482		}
2483cow_done:
2484		BUG_ON(!cow && ins_len);
2485
2486		p->nodes[level] = b;
2487		btrfs_clear_path_blocking(p, NULL, 0);
2488
2489		/*
2490		 * we have a lock on b and as long as we aren't changing
2491		 * the tree, there is no way to for the items in b to change.
2492		 * It is safe to drop the lock on our parent before we
2493		 * go through the expensive btree search on b.
2494		 *
2495		 * If cow is true, then we might be changing slot zero,
2496		 * which may require changing the parent.  So, we can't
2497		 * drop the lock until after we know which slot we're
2498		 * operating on.
2499		 */
2500		if (!cow)
2501			btrfs_unlock_up_safe(p, level + 1);
2502
2503		ret = bin_search(b, key, level, &slot);
 
 
 
 
 
 
 
 
2504
2505		if (level != 0) {
2506			int dec = 0;
2507			if (ret && slot > 0) {
2508				dec = 1;
2509				slot -= 1;
2510			}
2511			p->slots[level] = slot;
2512			err = setup_nodes_for_search(trans, root, p, b, level,
2513					     ins_len, &write_lock_level);
2514			if (err == -EAGAIN)
2515				goto again;
2516			if (err) {
2517				ret = err;
2518				goto done;
2519			}
2520			b = p->nodes[level];
2521			slot = p->slots[level];
2522
2523			/*
2524			 * slot 0 is special, if we change the key
2525			 * we have to update the parent pointer
2526			 * which means we must have a write lock
2527			 * on the parent
2528			 */
2529			if (slot == 0 && cow &&
2530			    write_lock_level < level + 1) {
2531				write_lock_level = level + 1;
2532				btrfs_release_path(p);
2533				goto again;
2534			}
2535
2536			unlock_up(p, level, lowest_unlock,
2537				  min_write_lock_level, &write_lock_level);
2538
2539			if (level == lowest_level) {
2540				if (dec)
2541					p->slots[level]++;
2542				goto done;
2543			}
2544
2545			err = read_block_for_search(trans, root, p,
2546						    &b, level, slot, key, 0);
2547			if (err == -EAGAIN)
2548				goto again;
2549			if (err) {
2550				ret = err;
2551				goto done;
2552			}
2553
2554			if (!p->skip_locking) {
2555				level = btrfs_header_level(b);
2556				if (level <= write_lock_level) {
2557					err = btrfs_try_tree_write_lock(b);
2558					if (!err) {
2559						btrfs_set_path_blocking(p);
2560						btrfs_tree_lock(b);
2561						btrfs_clear_path_blocking(p, b,
2562								  BTRFS_WRITE_LOCK);
2563					}
2564					p->locks[level] = BTRFS_WRITE_LOCK;
2565				} else {
2566					err = btrfs_try_tree_read_lock(b);
2567					if (!err) {
2568						btrfs_set_path_blocking(p);
2569						btrfs_tree_read_lock(b);
2570						btrfs_clear_path_blocking(p, b,
2571								  BTRFS_READ_LOCK);
2572					}
2573					p->locks[level] = BTRFS_READ_LOCK;
2574				}
2575				p->nodes[level] = b;
2576			}
2577		} else {
2578			p->slots[level] = slot;
2579			if (ins_len > 0 &&
2580			    btrfs_leaf_free_space(root, b) < ins_len) {
2581				if (write_lock_level < 1) {
2582					write_lock_level = 1;
2583					btrfs_release_path(p);
2584					goto again;
2585				}
2586
2587				btrfs_set_path_blocking(p);
2588				err = split_leaf(trans, root, key,
2589						 p, ins_len, ret == 0);
2590				btrfs_clear_path_blocking(p, NULL, 0);
2591
2592				BUG_ON(err > 0);
2593				if (err) {
2594					ret = err;
2595					goto done;
2596				}
2597			}
2598			if (!p->search_for_split)
2599				unlock_up(p, level, lowest_unlock,
2600					  min_write_lock_level, &write_lock_level);
2601			goto done;
2602		}
2603	}
2604	ret = 1;
2605done:
2606	/*
2607	 * we don't really know what they plan on doing with the path
2608	 * from here on, so for now just mark it as blocking
2609	 */
2610	if (!p->leave_spinning)
2611		btrfs_set_path_blocking(p);
2612	if (ret < 0)
2613		btrfs_release_path(p);
2614	return ret;
2615}
2616
2617/*
2618 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2619 * current state of the tree together with the operations recorded in the tree
2620 * modification log to search for the key in a previous version of this tree, as
2621 * denoted by the time_seq parameter.
2622 *
2623 * Naturally, there is no support for insert, delete or cow operations.
2624 *
2625 * The resulting path and return value will be set up as if we called
2626 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2627 */
2628int btrfs_search_old_slot(struct btrfs_root *root, struct btrfs_key *key,
2629			  struct btrfs_path *p, u64 time_seq)
2630{
 
2631	struct extent_buffer *b;
2632	int slot;
2633	int ret;
2634	int err;
2635	int level;
2636	int lowest_unlock = 1;
2637	u8 lowest_level = 0;
 
2638
2639	lowest_level = p->lowest_level;
2640	WARN_ON(p->nodes[0] != NULL);
2641
2642	if (p->search_commit_root) {
2643		BUG_ON(time_seq);
2644		return btrfs_search_slot(NULL, root, key, p, 0, 0);
2645	}
2646
2647again:
2648	b = get_old_root(root, time_seq);
2649	level = btrfs_header_level(b);
2650	p->locks[level] = BTRFS_READ_LOCK;
2651
2652	while (b) {
2653		level = btrfs_header_level(b);
2654		p->nodes[level] = b;
2655		btrfs_clear_path_blocking(p, NULL, 0);
2656
2657		/*
2658		 * we have a lock on b and as long as we aren't changing
2659		 * the tree, there is no way to for the items in b to change.
2660		 * It is safe to drop the lock on our parent before we
2661		 * go through the expensive btree search on b.
2662		 */
2663		btrfs_unlock_up_safe(p, level + 1);
2664
2665		ret = bin_search(b, key, level, &slot);
 
 
 
 
 
2666
2667		if (level != 0) {
2668			int dec = 0;
2669			if (ret && slot > 0) {
2670				dec = 1;
2671				slot -= 1;
2672			}
2673			p->slots[level] = slot;
2674			unlock_up(p, level, lowest_unlock, 0, NULL);
2675
2676			if (level == lowest_level) {
2677				if (dec)
2678					p->slots[level]++;
2679				goto done;
2680			}
2681
2682			err = read_block_for_search(NULL, root, p, &b, level,
2683						    slot, key, time_seq);
2684			if (err == -EAGAIN)
2685				goto again;
2686			if (err) {
2687				ret = err;
2688				goto done;
2689			}
2690
2691			level = btrfs_header_level(b);
2692			err = btrfs_try_tree_read_lock(b);
2693			if (!err) {
2694				btrfs_set_path_blocking(p);
2695				btrfs_tree_read_lock(b);
2696				btrfs_clear_path_blocking(p, b,
2697							  BTRFS_READ_LOCK);
2698			}
 
 
 
 
 
2699			p->locks[level] = BTRFS_READ_LOCK;
2700			p->nodes[level] = b;
2701			b = tree_mod_log_rewind(root->fs_info, b, time_seq);
2702			if (b != p->nodes[level]) {
2703				btrfs_tree_unlock_rw(p->nodes[level],
2704						     p->locks[level]);
2705				p->locks[level] = 0;
2706				p->nodes[level] = b;
2707			}
2708		} else {
2709			p->slots[level] = slot;
2710			unlock_up(p, level, lowest_unlock, 0, NULL);
2711			goto done;
2712		}
2713	}
2714	ret = 1;
2715done:
2716	if (!p->leave_spinning)
2717		btrfs_set_path_blocking(p);
2718	if (ret < 0)
2719		btrfs_release_path(p);
2720
2721	return ret;
2722}
2723
2724/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2725 * adjust the pointers going up the tree, starting at level
2726 * making sure the right key of each node is points to 'key'.
2727 * This is used after shifting pointers to the left, so it stops
2728 * fixing up pointers when a given leaf/node is not in slot 0 of the
2729 * higher levels
2730 *
2731 */
2732static void fixup_low_keys(struct btrfs_trans_handle *trans,
2733			   struct btrfs_root *root, struct btrfs_path *path,
2734			   struct btrfs_disk_key *key, int level)
2735{
2736	int i;
2737	struct extent_buffer *t;
2738
2739	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2740		int tslot = path->slots[i];
2741		if (!path->nodes[i])
2742			break;
2743		t = path->nodes[i];
2744		tree_mod_log_set_node_key(root->fs_info, t, key, tslot, 1);
2745		btrfs_set_node_key(t, key, tslot);
2746		btrfs_mark_buffer_dirty(path->nodes[i]);
2747		if (tslot != 0)
2748			break;
2749	}
2750}
2751
2752/*
2753 * update item key.
2754 *
2755 * This function isn't completely safe. It's the caller's responsibility
2756 * that the new key won't break the order
2757 */
2758void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
2759			     struct btrfs_root *root, struct btrfs_path *path,
2760			     struct btrfs_key *new_key)
2761{
2762	struct btrfs_disk_key disk_key;
2763	struct extent_buffer *eb;
2764	int slot;
2765
2766	eb = path->nodes[0];
2767	slot = path->slots[0];
2768	if (slot > 0) {
2769		btrfs_item_key(eb, &disk_key, slot - 1);
2770		BUG_ON(comp_keys(&disk_key, new_key) >= 0);
2771	}
2772	if (slot < btrfs_header_nritems(eb) - 1) {
2773		btrfs_item_key(eb, &disk_key, slot + 1);
2774		BUG_ON(comp_keys(&disk_key, new_key) <= 0);
2775	}
2776
2777	btrfs_cpu_key_to_disk(&disk_key, new_key);
2778	btrfs_set_item_key(eb, &disk_key, slot);
2779	btrfs_mark_buffer_dirty(eb);
2780	if (slot == 0)
2781		fixup_low_keys(trans, root, path, &disk_key, 1);
2782}
2783
2784/*
2785 * try to push data from one node into the next node left in the
2786 * tree.
2787 *
2788 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2789 * error, and > 0 if there was no room in the left hand block.
2790 */
2791static int push_node_left(struct btrfs_trans_handle *trans,
2792			  struct btrfs_root *root, struct extent_buffer *dst,
 
2793			  struct extent_buffer *src, int empty)
2794{
2795	int push_items = 0;
2796	int src_nritems;
2797	int dst_nritems;
2798	int ret = 0;
2799
2800	src_nritems = btrfs_header_nritems(src);
2801	dst_nritems = btrfs_header_nritems(dst);
2802	push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
2803	WARN_ON(btrfs_header_generation(src) != trans->transid);
2804	WARN_ON(btrfs_header_generation(dst) != trans->transid);
2805
2806	if (!empty && src_nritems <= 8)
2807		return 1;
2808
2809	if (push_items <= 0)
2810		return 1;
2811
2812	if (empty) {
2813		push_items = min(src_nritems, push_items);
2814		if (push_items < src_nritems) {
2815			/* leave at least 8 pointers in the node if
2816			 * we aren't going to empty it
2817			 */
2818			if (src_nritems - push_items < 8) {
2819				if (push_items <= 8)
2820					return 1;
2821				push_items -= 8;
2822			}
2823		}
2824	} else
2825		push_items = min(src_nritems - 8, push_items);
2826
2827	tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
2828			     push_items);
 
 
 
 
2829	copy_extent_buffer(dst, src,
2830			   btrfs_node_key_ptr_offset(dst_nritems),
2831			   btrfs_node_key_ptr_offset(0),
2832			   push_items * sizeof(struct btrfs_key_ptr));
2833
2834	if (push_items < src_nritems) {
2835		tree_mod_log_eb_move(root->fs_info, src, 0, push_items,
2836				     src_nritems - push_items);
 
 
2837		memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
2838				      btrfs_node_key_ptr_offset(push_items),
2839				      (src_nritems - push_items) *
2840				      sizeof(struct btrfs_key_ptr));
2841	}
2842	btrfs_set_header_nritems(src, src_nritems - push_items);
2843	btrfs_set_header_nritems(dst, dst_nritems + push_items);
2844	btrfs_mark_buffer_dirty(src);
2845	btrfs_mark_buffer_dirty(dst);
2846
2847	return ret;
2848}
2849
2850/*
2851 * try to push data from one node into the next node right in the
2852 * tree.
2853 *
2854 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2855 * error, and > 0 if there was no room in the right hand block.
2856 *
2857 * this will  only push up to 1/2 the contents of the left node over
2858 */
2859static int balance_node_right(struct btrfs_trans_handle *trans,
2860			      struct btrfs_root *root,
2861			      struct extent_buffer *dst,
2862			      struct extent_buffer *src)
2863{
2864	int push_items = 0;
2865	int max_push;
2866	int src_nritems;
2867	int dst_nritems;
2868	int ret = 0;
2869
2870	WARN_ON(btrfs_header_generation(src) != trans->transid);
2871	WARN_ON(btrfs_header_generation(dst) != trans->transid);
2872
2873	src_nritems = btrfs_header_nritems(src);
2874	dst_nritems = btrfs_header_nritems(dst);
2875	push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
2876	if (push_items <= 0)
2877		return 1;
2878
2879	if (src_nritems < 4)
2880		return 1;
2881
2882	max_push = src_nritems / 2 + 1;
2883	/* don't try to empty the node */
2884	if (max_push >= src_nritems)
2885		return 1;
2886
2887	if (max_push < push_items)
2888		push_items = max_push;
2889
2890	tree_mod_log_eb_move(root->fs_info, dst, push_items, 0, dst_nritems);
2891	memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
2892				      btrfs_node_key_ptr_offset(0),
2893				      (dst_nritems) *
2894				      sizeof(struct btrfs_key_ptr));
2895
2896	tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
2897			     src_nritems - push_items, push_items);
 
 
 
 
2898	copy_extent_buffer(dst, src,
2899			   btrfs_node_key_ptr_offset(0),
2900			   btrfs_node_key_ptr_offset(src_nritems - push_items),
2901			   push_items * sizeof(struct btrfs_key_ptr));
2902
2903	btrfs_set_header_nritems(src, src_nritems - push_items);
2904	btrfs_set_header_nritems(dst, dst_nritems + push_items);
2905
2906	btrfs_mark_buffer_dirty(src);
2907	btrfs_mark_buffer_dirty(dst);
2908
2909	return ret;
2910}
2911
2912/*
2913 * helper function to insert a new root level in the tree.
2914 * A new node is allocated, and a single item is inserted to
2915 * point to the existing root
2916 *
2917 * returns zero on success or < 0 on failure.
2918 */
2919static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2920			   struct btrfs_root *root,
2921			   struct btrfs_path *path, int level)
2922{
 
2923	u64 lower_gen;
2924	struct extent_buffer *lower;
2925	struct extent_buffer *c;
2926	struct extent_buffer *old;
2927	struct btrfs_disk_key lower_key;
2928
2929	BUG_ON(path->nodes[level]);
2930	BUG_ON(path->nodes[level-1] != root->node);
2931
2932	lower = path->nodes[level-1];
2933	if (level == 1)
2934		btrfs_item_key(lower, &lower_key, 0);
2935	else
2936		btrfs_node_key(lower, &lower_key, 0);
2937
2938	c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
2939				   root->root_key.objectid, &lower_key,
2940				   level, root->node->start, 0);
2941	if (IS_ERR(c))
2942		return PTR_ERR(c);
2943
2944	root_add_used(root, root->nodesize);
2945
2946	memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
2947	btrfs_set_header_nritems(c, 1);
2948	btrfs_set_header_level(c, level);
2949	btrfs_set_header_bytenr(c, c->start);
2950	btrfs_set_header_generation(c, trans->transid);
2951	btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
2952	btrfs_set_header_owner(c, root->root_key.objectid);
2953
2954	write_extent_buffer(c, root->fs_info->fsid,
2955			    (unsigned long)btrfs_header_fsid(c),
2956			    BTRFS_FSID_SIZE);
2957
2958	write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
2959			    (unsigned long)btrfs_header_chunk_tree_uuid(c),
2960			    BTRFS_UUID_SIZE);
2961
2962	btrfs_set_node_key(c, &lower_key, 0);
2963	btrfs_set_node_blockptr(c, 0, lower->start);
2964	lower_gen = btrfs_header_generation(lower);
2965	WARN_ON(lower_gen != trans->transid);
2966
2967	btrfs_set_node_ptr_generation(c, 0, lower_gen);
2968
2969	btrfs_mark_buffer_dirty(c);
2970
2971	old = root->node;
2972	tree_mod_log_set_root_pointer(root, c);
2973	rcu_assign_pointer(root->node, c);
2974
2975	/* the super has an extra ref to root->node */
2976	free_extent_buffer(old);
2977
2978	add_root_to_dirty_list(root);
2979	extent_buffer_get(c);
2980	path->nodes[level] = c;
2981	path->locks[level] = BTRFS_WRITE_LOCK;
2982	path->slots[level] = 0;
2983	return 0;
2984}
2985
2986/*
2987 * worker function to insert a single pointer in a node.
2988 * the node should have enough room for the pointer already
2989 *
2990 * slot and level indicate where you want the key to go, and
2991 * blocknr is the block the key points to.
2992 */
2993static void insert_ptr(struct btrfs_trans_handle *trans,
2994		       struct btrfs_root *root, struct btrfs_path *path,
2995		       struct btrfs_disk_key *key, u64 bytenr,
2996		       int slot, int level)
2997{
2998	struct extent_buffer *lower;
2999	int nritems;
3000	int ret;
3001
3002	BUG_ON(!path->nodes[level]);
3003	btrfs_assert_tree_locked(path->nodes[level]);
3004	lower = path->nodes[level];
3005	nritems = btrfs_header_nritems(lower);
3006	BUG_ON(slot > nritems);
3007	BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root));
3008	if (slot != nritems) {
3009		if (level)
3010			tree_mod_log_eb_move(root->fs_info, lower, slot + 1,
3011					     slot, nritems - slot);
3012		memmove_extent_buffer(lower,
3013			      btrfs_node_key_ptr_offset(slot + 1),
3014			      btrfs_node_key_ptr_offset(slot),
3015			      (nritems - slot) * sizeof(struct btrfs_key_ptr));
3016	}
3017	if (level) {
3018		ret = tree_mod_log_insert_key(root->fs_info, lower, slot,
3019					      MOD_LOG_KEY_ADD);
3020		BUG_ON(ret < 0);
3021	}
3022	btrfs_set_node_key(lower, key, slot);
3023	btrfs_set_node_blockptr(lower, slot, bytenr);
3024	WARN_ON(trans->transid == 0);
3025	btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3026	btrfs_set_header_nritems(lower, nritems + 1);
3027	btrfs_mark_buffer_dirty(lower);
3028}
3029
3030/*
3031 * split the node at the specified level in path in two.
3032 * The path is corrected to point to the appropriate node after the split
3033 *
3034 * Before splitting this tries to make some room in the node by pushing
3035 * left and right, if either one works, it returns right away.
3036 *
3037 * returns 0 on success and < 0 on failure
3038 */
3039static noinline int split_node(struct btrfs_trans_handle *trans,
3040			       struct btrfs_root *root,
3041			       struct btrfs_path *path, int level)
3042{
 
3043	struct extent_buffer *c;
3044	struct extent_buffer *split;
3045	struct btrfs_disk_key disk_key;
3046	int mid;
3047	int ret;
3048	u32 c_nritems;
3049
3050	c = path->nodes[level];
3051	WARN_ON(btrfs_header_generation(c) != trans->transid);
3052	if (c == root->node) {
3053		/* trying to split the root, lets make a new one */
 
 
 
 
 
 
 
 
 
3054		ret = insert_new_root(trans, root, path, level + 1);
3055		if (ret)
3056			return ret;
3057	} else {
3058		ret = push_nodes_for_insert(trans, root, path, level);
3059		c = path->nodes[level];
3060		if (!ret && btrfs_header_nritems(c) <
3061		    BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
3062			return 0;
3063		if (ret < 0)
3064			return ret;
3065	}
3066
3067	c_nritems = btrfs_header_nritems(c);
3068	mid = (c_nritems + 1) / 2;
3069	btrfs_node_key(c, &disk_key, mid);
3070
3071	split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
3072					root->root_key.objectid,
3073					&disk_key, level, c->start, 0);
3074	if (IS_ERR(split))
3075		return PTR_ERR(split);
3076
3077	root_add_used(root, root->nodesize);
3078
3079	memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
3080	btrfs_set_header_level(split, btrfs_header_level(c));
3081	btrfs_set_header_bytenr(split, split->start);
3082	btrfs_set_header_generation(split, trans->transid);
3083	btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
3084	btrfs_set_header_owner(split, root->root_key.objectid);
3085	write_extent_buffer(split, root->fs_info->fsid,
3086			    (unsigned long)btrfs_header_fsid(split),
3087			    BTRFS_FSID_SIZE);
3088	write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
3089			    (unsigned long)btrfs_header_chunk_tree_uuid(split),
3090			    BTRFS_UUID_SIZE);
3091
3092	tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid);
 
 
 
 
3093	copy_extent_buffer(split, c,
3094			   btrfs_node_key_ptr_offset(0),
3095			   btrfs_node_key_ptr_offset(mid),
3096			   (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3097	btrfs_set_header_nritems(split, c_nritems - mid);
3098	btrfs_set_header_nritems(c, mid);
3099	ret = 0;
3100
3101	btrfs_mark_buffer_dirty(c);
3102	btrfs_mark_buffer_dirty(split);
3103
3104	insert_ptr(trans, root, path, &disk_key, split->start,
3105		   path->slots[level + 1] + 1, level + 1);
3106
3107	if (path->slots[level] >= mid) {
3108		path->slots[level] -= mid;
3109		btrfs_tree_unlock(c);
3110		free_extent_buffer(c);
3111		path->nodes[level] = split;
3112		path->slots[level + 1] += 1;
3113	} else {
3114		btrfs_tree_unlock(split);
3115		free_extent_buffer(split);
3116	}
3117	return ret;
3118}
3119
3120/*
3121 * how many bytes are required to store the items in a leaf.  start
3122 * and nr indicate which items in the leaf to check.  This totals up the
3123 * space used both by the item structs and the item data
3124 */
3125static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3126{
 
 
 
3127	int data_len;
3128	int nritems = btrfs_header_nritems(l);
3129	int end = min(nritems, start + nr) - 1;
3130
3131	if (!nr)
3132		return 0;
3133	data_len = btrfs_item_end_nr(l, start);
3134	data_len = data_len - btrfs_item_offset_nr(l, end);
 
 
 
 
3135	data_len += sizeof(struct btrfs_item) * nr;
3136	WARN_ON(data_len < 0);
3137	return data_len;
3138}
3139
3140/*
3141 * The space between the end of the leaf items and
3142 * the start of the leaf data.  IOW, how much room
3143 * the leaf has left for both items and data
3144 */
3145noinline int btrfs_leaf_free_space(struct btrfs_root *root,
3146				   struct extent_buffer *leaf)
3147{
3148	int nritems = btrfs_header_nritems(leaf);
3149	int ret;
3150	ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
 
3151	if (ret < 0) {
3152		printk(KERN_CRIT "leaf free space ret %d, leaf data size %lu, "
3153		       "used %d nritems %d\n",
3154		       ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
3155		       leaf_space_used(leaf, 0, nritems), nritems);
 
3156	}
3157	return ret;
3158}
3159
3160/*
3161 * min slot controls the lowest index we're willing to push to the
3162 * right.  We'll push up to and including min_slot, but no lower
3163 */
3164static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3165				      struct btrfs_root *root,
3166				      struct btrfs_path *path,
3167				      int data_size, int empty,
3168				      struct extent_buffer *right,
3169				      int free_space, u32 left_nritems,
3170				      u32 min_slot)
3171{
3172	struct extent_buffer *left = path->nodes[0];
3173	struct extent_buffer *upper = path->nodes[1];
3174	struct btrfs_map_token token;
3175	struct btrfs_disk_key disk_key;
3176	int slot;
3177	u32 i;
3178	int push_space = 0;
3179	int push_items = 0;
3180	struct btrfs_item *item;
3181	u32 nr;
3182	u32 right_nritems;
3183	u32 data_end;
3184	u32 this_item_size;
3185
3186	btrfs_init_map_token(&token);
3187
3188	if (empty)
3189		nr = 0;
3190	else
3191		nr = max_t(u32, 1, min_slot);
3192
3193	if (path->slots[0] >= left_nritems)
3194		push_space += data_size;
3195
3196	slot = path->slots[1];
3197	i = left_nritems - 1;
3198	while (i >= nr) {
3199		item = btrfs_item_nr(left, i);
3200
3201		if (!empty && push_items > 0) {
3202			if (path->slots[0] > i)
3203				break;
3204			if (path->slots[0] == i) {
3205				int space = btrfs_leaf_free_space(root, left);
3206				if (space + push_space * 2 > free_space)
3207					break;
3208			}
3209		}
3210
3211		if (path->slots[0] == i)
3212			push_space += data_size;
3213
3214		this_item_size = btrfs_item_size(left, item);
3215		if (this_item_size + sizeof(*item) + push_space > free_space)
3216			break;
3217
3218		push_items++;
3219		push_space += this_item_size + sizeof(*item);
3220		if (i == 0)
3221			break;
3222		i--;
3223	}
3224
3225	if (push_items == 0)
3226		goto out_unlock;
3227
3228	if (!empty && push_items == left_nritems)
3229		WARN_ON(1);
3230
3231	/* push left to right */
3232	right_nritems = btrfs_header_nritems(right);
3233
3234	push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3235	push_space -= leaf_data_end(root, left);
3236
3237	/* make room in the right data area */
3238	data_end = leaf_data_end(root, right);
3239	memmove_extent_buffer(right,
3240			      btrfs_leaf_data(right) + data_end - push_space,
3241			      btrfs_leaf_data(right) + data_end,
3242			      BTRFS_LEAF_DATA_SIZE(root) - data_end);
3243
3244	/* copy from the left data area */
3245	copy_extent_buffer(right, left, btrfs_leaf_data(right) +
3246		     BTRFS_LEAF_DATA_SIZE(root) - push_space,
3247		     btrfs_leaf_data(left) + leaf_data_end(root, left),
3248		     push_space);
3249
3250	memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3251			      btrfs_item_nr_offset(0),
3252			      right_nritems * sizeof(struct btrfs_item));
3253
3254	/* copy the items from left to right */
3255	copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3256		   btrfs_item_nr_offset(left_nritems - push_items),
3257		   push_items * sizeof(struct btrfs_item));
3258
3259	/* update the item pointers */
3260	right_nritems += push_items;
3261	btrfs_set_header_nritems(right, right_nritems);
3262	push_space = BTRFS_LEAF_DATA_SIZE(root);
3263	for (i = 0; i < right_nritems; i++) {
3264		item = btrfs_item_nr(right, i);
3265		push_space -= btrfs_token_item_size(right, item, &token);
3266		btrfs_set_token_item_offset(right, item, push_space, &token);
3267	}
3268
3269	left_nritems -= push_items;
3270	btrfs_set_header_nritems(left, left_nritems);
3271
3272	if (left_nritems)
3273		btrfs_mark_buffer_dirty(left);
3274	else
3275		clean_tree_block(trans, root, left);
3276
3277	btrfs_mark_buffer_dirty(right);
3278
3279	btrfs_item_key(right, &disk_key, 0);
3280	btrfs_set_node_key(upper, &disk_key, slot + 1);
3281	btrfs_mark_buffer_dirty(upper);
3282
3283	/* then fixup the leaf pointer in the path */
3284	if (path->slots[0] >= left_nritems) {
3285		path->slots[0] -= left_nritems;
3286		if (btrfs_header_nritems(path->nodes[0]) == 0)
3287			clean_tree_block(trans, root, path->nodes[0]);
3288		btrfs_tree_unlock(path->nodes[0]);
3289		free_extent_buffer(path->nodes[0]);
3290		path->nodes[0] = right;
3291		path->slots[1] += 1;
3292	} else {
3293		btrfs_tree_unlock(right);
3294		free_extent_buffer(right);
3295	}
3296	return 0;
3297
3298out_unlock:
3299	btrfs_tree_unlock(right);
3300	free_extent_buffer(right);
3301	return 1;
3302}
3303
3304/*
3305 * push some data in the path leaf to the right, trying to free up at
3306 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3307 *
3308 * returns 1 if the push failed because the other node didn't have enough
3309 * room, 0 if everything worked out and < 0 if there were major errors.
3310 *
3311 * this will push starting from min_slot to the end of the leaf.  It won't
3312 * push any slot lower than min_slot
3313 */
3314static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3315			   *root, struct btrfs_path *path,
3316			   int min_data_size, int data_size,
3317			   int empty, u32 min_slot)
3318{
 
3319	struct extent_buffer *left = path->nodes[0];
3320	struct extent_buffer *right;
3321	struct extent_buffer *upper;
3322	int slot;
3323	int free_space;
3324	u32 left_nritems;
3325	int ret;
3326
3327	if (!path->nodes[1])
3328		return 1;
3329
3330	slot = path->slots[1];
3331	upper = path->nodes[1];
3332	if (slot >= btrfs_header_nritems(upper) - 1)
3333		return 1;
3334
3335	btrfs_assert_tree_locked(path->nodes[1]);
3336
3337	right = read_node_slot(root, upper, slot + 1);
3338	if (right == NULL)
 
 
 
 
3339		return 1;
3340
3341	btrfs_tree_lock(right);
3342	btrfs_set_lock_blocking(right);
3343
3344	free_space = btrfs_leaf_free_space(root, right);
3345	if (free_space < data_size)
3346		goto out_unlock;
3347
3348	/* cow and double check */
3349	ret = btrfs_cow_block(trans, root, right, upper,
3350			      slot + 1, &right);
3351	if (ret)
3352		goto out_unlock;
3353
3354	free_space = btrfs_leaf_free_space(root, right);
3355	if (free_space < data_size)
3356		goto out_unlock;
3357
3358	left_nritems = btrfs_header_nritems(left);
3359	if (left_nritems == 0)
3360		goto out_unlock;
3361
3362	return __push_leaf_right(trans, root, path, min_data_size, empty,
 
 
 
 
 
 
 
 
 
 
 
 
 
3363				right, free_space, left_nritems, min_slot);
3364out_unlock:
3365	btrfs_tree_unlock(right);
3366	free_extent_buffer(right);
3367	return 1;
3368}
3369
3370/*
3371 * push some data in the path leaf to the left, trying to free up at
3372 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3373 *
3374 * max_slot can put a limit on how far into the leaf we'll push items.  The
3375 * item at 'max_slot' won't be touched.  Use (u32)-1 to make us do all the
3376 * items
3377 */
3378static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3379				     struct btrfs_root *root,
3380				     struct btrfs_path *path, int data_size,
3381				     int empty, struct extent_buffer *left,
3382				     int free_space, u32 right_nritems,
3383				     u32 max_slot)
3384{
3385	struct btrfs_disk_key disk_key;
3386	struct extent_buffer *right = path->nodes[0];
3387	int i;
3388	int push_space = 0;
3389	int push_items = 0;
3390	struct btrfs_item *item;
3391	u32 old_left_nritems;
3392	u32 nr;
3393	int ret = 0;
3394	u32 this_item_size;
3395	u32 old_left_item_size;
3396	struct btrfs_map_token token;
3397
3398	btrfs_init_map_token(&token);
3399
3400	if (empty)
3401		nr = min(right_nritems, max_slot);
3402	else
3403		nr = min(right_nritems - 1, max_slot);
3404
3405	for (i = 0; i < nr; i++) {
3406		item = btrfs_item_nr(right, i);
3407
3408		if (!empty && push_items > 0) {
3409			if (path->slots[0] < i)
3410				break;
3411			if (path->slots[0] == i) {
3412				int space = btrfs_leaf_free_space(root, right);
3413				if (space + push_space * 2 > free_space)
3414					break;
3415			}
3416		}
3417
3418		if (path->slots[0] == i)
3419			push_space += data_size;
3420
3421		this_item_size = btrfs_item_size(right, item);
3422		if (this_item_size + sizeof(*item) + push_space > free_space)
3423			break;
3424
3425		push_items++;
3426		push_space += this_item_size + sizeof(*item);
3427	}
3428
3429	if (push_items == 0) {
3430		ret = 1;
3431		goto out;
3432	}
3433	if (!empty && push_items == btrfs_header_nritems(right))
3434		WARN_ON(1);
3435
3436	/* push data from right to left */
3437	copy_extent_buffer(left, right,
3438			   btrfs_item_nr_offset(btrfs_header_nritems(left)),
3439			   btrfs_item_nr_offset(0),
3440			   push_items * sizeof(struct btrfs_item));
3441
3442	push_space = BTRFS_LEAF_DATA_SIZE(root) -
3443		     btrfs_item_offset_nr(right, push_items - 1);
3444
3445	copy_extent_buffer(left, right, btrfs_leaf_data(left) +
3446		     leaf_data_end(root, left) - push_space,
3447		     btrfs_leaf_data(right) +
3448		     btrfs_item_offset_nr(right, push_items - 1),
3449		     push_space);
3450	old_left_nritems = btrfs_header_nritems(left);
3451	BUG_ON(old_left_nritems <= 0);
3452
3453	old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3454	for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3455		u32 ioff;
3456
3457		item = btrfs_item_nr(left, i);
3458
3459		ioff = btrfs_token_item_offset(left, item, &token);
3460		btrfs_set_token_item_offset(left, item,
3461		      ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size),
3462		      &token);
3463	}
3464	btrfs_set_header_nritems(left, old_left_nritems + push_items);
3465
3466	/* fixup right node */
3467	if (push_items > right_nritems) {
3468		printk(KERN_CRIT "push items %d nr %u\n", push_items,
3469		       right_nritems);
3470		WARN_ON(1);
3471	}
3472
3473	if (push_items < right_nritems) {
3474		push_space = btrfs_item_offset_nr(right, push_items - 1) -
3475						  leaf_data_end(root, right);
3476		memmove_extent_buffer(right, btrfs_leaf_data(right) +
3477				      BTRFS_LEAF_DATA_SIZE(root) - push_space,
3478				      btrfs_leaf_data(right) +
3479				      leaf_data_end(root, right), push_space);
3480
3481		memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3482			      btrfs_item_nr_offset(push_items),
3483			     (btrfs_header_nritems(right) - push_items) *
3484			     sizeof(struct btrfs_item));
3485	}
3486	right_nritems -= push_items;
3487	btrfs_set_header_nritems(right, right_nritems);
3488	push_space = BTRFS_LEAF_DATA_SIZE(root);
3489	for (i = 0; i < right_nritems; i++) {
3490		item = btrfs_item_nr(right, i);
3491
3492		push_space = push_space - btrfs_token_item_size(right,
3493								item, &token);
3494		btrfs_set_token_item_offset(right, item, push_space, &token);
3495	}
3496
3497	btrfs_mark_buffer_dirty(left);
3498	if (right_nritems)
3499		btrfs_mark_buffer_dirty(right);
3500	else
3501		clean_tree_block(trans, root, right);
3502
3503	btrfs_item_key(right, &disk_key, 0);
3504	fixup_low_keys(trans, root, path, &disk_key, 1);
3505
3506	/* then fixup the leaf pointer in the path */
3507	if (path->slots[0] < push_items) {
3508		path->slots[0] += old_left_nritems;
3509		btrfs_tree_unlock(path->nodes[0]);
3510		free_extent_buffer(path->nodes[0]);
3511		path->nodes[0] = left;
3512		path->slots[1] -= 1;
3513	} else {
3514		btrfs_tree_unlock(left);
3515		free_extent_buffer(left);
3516		path->slots[0] -= push_items;
3517	}
3518	BUG_ON(path->slots[0] < 0);
3519	return ret;
3520out:
3521	btrfs_tree_unlock(left);
3522	free_extent_buffer(left);
3523	return ret;
3524}
3525
3526/*
3527 * push some data in the path leaf to the left, trying to free up at
3528 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3529 *
3530 * max_slot can put a limit on how far into the leaf we'll push items.  The
3531 * item at 'max_slot' won't be touched.  Use (u32)-1 to make us push all the
3532 * items
3533 */
3534static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3535			  *root, struct btrfs_path *path, int min_data_size,
3536			  int data_size, int empty, u32 max_slot)
3537{
 
3538	struct extent_buffer *right = path->nodes[0];
3539	struct extent_buffer *left;
3540	int slot;
3541	int free_space;
3542	u32 right_nritems;
3543	int ret = 0;
3544
3545	slot = path->slots[1];
3546	if (slot == 0)
3547		return 1;
3548	if (!path->nodes[1])
3549		return 1;
3550
3551	right_nritems = btrfs_header_nritems(right);
3552	if (right_nritems == 0)
3553		return 1;
3554
3555	btrfs_assert_tree_locked(path->nodes[1]);
3556
3557	left = read_node_slot(root, path->nodes[1], slot - 1);
3558	if (left == NULL)
 
 
 
 
3559		return 1;
3560
3561	btrfs_tree_lock(left);
3562	btrfs_set_lock_blocking(left);
3563
3564	free_space = btrfs_leaf_free_space(root, left);
3565	if (free_space < data_size) {
3566		ret = 1;
3567		goto out;
3568	}
3569
3570	/* cow and double check */
3571	ret = btrfs_cow_block(trans, root, left,
3572			      path->nodes[1], slot - 1, &left);
3573	if (ret) {
3574		/* we hit -ENOSPC, but it isn't fatal here */
3575		if (ret == -ENOSPC)
3576			ret = 1;
3577		goto out;
3578	}
3579
3580	free_space = btrfs_leaf_free_space(root, left);
3581	if (free_space < data_size) {
3582		ret = 1;
3583		goto out;
3584	}
3585
3586	return __push_leaf_left(trans, root, path, min_data_size,
3587			       empty, left, free_space, right_nritems,
3588			       max_slot);
3589out:
3590	btrfs_tree_unlock(left);
3591	free_extent_buffer(left);
3592	return ret;
3593}
3594
3595/*
3596 * split the path's leaf in two, making sure there is at least data_size
3597 * available for the resulting leaf level of the path.
3598 */
3599static noinline void copy_for_split(struct btrfs_trans_handle *trans,
3600				    struct btrfs_root *root,
3601				    struct btrfs_path *path,
3602				    struct extent_buffer *l,
3603				    struct extent_buffer *right,
3604				    int slot, int mid, int nritems)
3605{
3606	int data_copy_size;
3607	int rt_data_off;
3608	int i;
3609	struct btrfs_disk_key disk_key;
3610	struct btrfs_map_token token;
3611
3612	btrfs_init_map_token(&token);
3613
3614	nritems = nritems - mid;
3615	btrfs_set_header_nritems(right, nritems);
3616	data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
3617
3618	copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
3619			   btrfs_item_nr_offset(mid),
3620			   nritems * sizeof(struct btrfs_item));
3621
3622	copy_extent_buffer(right, l,
3623		     btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
3624		     data_copy_size, btrfs_leaf_data(l) +
3625		     leaf_data_end(root, l), data_copy_size);
3626
3627	rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
3628		      btrfs_item_end_nr(l, mid);
3629
3630	for (i = 0; i < nritems; i++) {
3631		struct btrfs_item *item = btrfs_item_nr(right, i);
3632		u32 ioff;
3633
3634		ioff = btrfs_token_item_offset(right, item, &token);
3635		btrfs_set_token_item_offset(right, item,
3636					    ioff + rt_data_off, &token);
3637	}
3638
3639	btrfs_set_header_nritems(l, mid);
3640	btrfs_item_key(right, &disk_key, 0);
3641	insert_ptr(trans, root, path, &disk_key, right->start,
3642		   path->slots[1] + 1, 1);
3643
3644	btrfs_mark_buffer_dirty(right);
3645	btrfs_mark_buffer_dirty(l);
3646	BUG_ON(path->slots[0] != slot);
3647
3648	if (mid <= slot) {
3649		btrfs_tree_unlock(path->nodes[0]);
3650		free_extent_buffer(path->nodes[0]);
3651		path->nodes[0] = right;
3652		path->slots[0] -= mid;
3653		path->slots[1] += 1;
3654	} else {
3655		btrfs_tree_unlock(right);
3656		free_extent_buffer(right);
3657	}
3658
3659	BUG_ON(path->slots[0] < 0);
3660}
3661
3662/*
3663 * double splits happen when we need to insert a big item in the middle
3664 * of a leaf.  A double split can leave us with 3 mostly empty leaves:
3665 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3666 *          A                 B                 C
3667 *
3668 * We avoid this by trying to push the items on either side of our target
3669 * into the adjacent leaves.  If all goes well we can avoid the double split
3670 * completely.
3671 */
3672static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3673					  struct btrfs_root *root,
3674					  struct btrfs_path *path,
3675					  int data_size)
3676{
 
3677	int ret;
3678	int progress = 0;
3679	int slot;
3680	u32 nritems;
 
3681
3682	slot = path->slots[0];
 
 
3683
3684	/*
3685	 * try to push all the items after our slot into the
3686	 * right leaf
3687	 */
3688	ret = push_leaf_right(trans, root, path, 1, data_size, 0, slot);
3689	if (ret < 0)
3690		return ret;
3691
3692	if (ret == 0)
3693		progress++;
3694
3695	nritems = btrfs_header_nritems(path->nodes[0]);
3696	/*
3697	 * our goal is to get our slot at the start or end of a leaf.  If
3698	 * we've done so we're done
3699	 */
3700	if (path->slots[0] == 0 || path->slots[0] == nritems)
3701		return 0;
3702
3703	if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
3704		return 0;
3705
3706	/* try to push all the items before our slot into the next leaf */
3707	slot = path->slots[0];
3708	ret = push_leaf_left(trans, root, path, 1, data_size, 0, slot);
3709	if (ret < 0)
3710		return ret;
3711
3712	if (ret == 0)
3713		progress++;
3714
3715	if (progress)
3716		return 0;
3717	return 1;
3718}
3719
3720/*
3721 * split the path's leaf in two, making sure there is at least data_size
3722 * available for the resulting leaf level of the path.
3723 *
3724 * returns 0 if all went well and < 0 on failure.
3725 */
3726static noinline int split_leaf(struct btrfs_trans_handle *trans,
3727			       struct btrfs_root *root,
3728			       struct btrfs_key *ins_key,
3729			       struct btrfs_path *path, int data_size,
3730			       int extend)
3731{
3732	struct btrfs_disk_key disk_key;
3733	struct extent_buffer *l;
3734	u32 nritems;
3735	int mid;
3736	int slot;
3737	struct extent_buffer *right;
 
3738	int ret = 0;
3739	int wret;
3740	int split;
3741	int num_doubles = 0;
3742	int tried_avoid_double = 0;
3743
3744	l = path->nodes[0];
3745	slot = path->slots[0];
3746	if (extend && data_size + btrfs_item_size_nr(l, slot) +
3747	    sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root))
3748		return -EOVERFLOW;
3749
3750	/* first try to make some room by pushing left and right */
3751	if (data_size) {
3752		wret = push_leaf_right(trans, root, path, data_size,
3753				       data_size, 0, 0);
 
 
 
 
 
3754		if (wret < 0)
3755			return wret;
3756		if (wret) {
3757			wret = push_leaf_left(trans, root, path, data_size,
3758					      data_size, 0, (u32)-1);
3759			if (wret < 0)
3760				return wret;
3761		}
3762		l = path->nodes[0];
3763
3764		/* did the pushes work? */
3765		if (btrfs_leaf_free_space(root, l) >= data_size)
3766			return 0;
3767	}
3768
3769	if (!path->nodes[1]) {
3770		ret = insert_new_root(trans, root, path, 1);
3771		if (ret)
3772			return ret;
3773	}
3774again:
3775	split = 1;
3776	l = path->nodes[0];
3777	slot = path->slots[0];
3778	nritems = btrfs_header_nritems(l);
3779	mid = (nritems + 1) / 2;
3780
3781	if (mid <= slot) {
3782		if (nritems == 1 ||
3783		    leaf_space_used(l, mid, nritems - mid) + data_size >
3784			BTRFS_LEAF_DATA_SIZE(root)) {
3785			if (slot >= nritems) {
3786				split = 0;
3787			} else {
3788				mid = slot;
3789				if (mid != nritems &&
3790				    leaf_space_used(l, mid, nritems - mid) +
3791				    data_size > BTRFS_LEAF_DATA_SIZE(root)) {
3792					if (data_size && !tried_avoid_double)
3793						goto push_for_double;
3794					split = 2;
3795				}
3796			}
3797		}
3798	} else {
3799		if (leaf_space_used(l, 0, mid) + data_size >
3800			BTRFS_LEAF_DATA_SIZE(root)) {
3801			if (!extend && data_size && slot == 0) {
3802				split = 0;
3803			} else if ((extend || !data_size) && slot == 0) {
3804				mid = 1;
3805			} else {
3806				mid = slot;
3807				if (mid != nritems &&
3808				    leaf_space_used(l, mid, nritems - mid) +
3809				    data_size > BTRFS_LEAF_DATA_SIZE(root)) {
3810					if (data_size && !tried_avoid_double)
3811						goto push_for_double;
3812					split = 2 ;
3813				}
3814			}
3815		}
3816	}
3817
3818	if (split == 0)
3819		btrfs_cpu_key_to_disk(&disk_key, ins_key);
3820	else
3821		btrfs_item_key(l, &disk_key, mid);
3822
3823	right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
3824					root->root_key.objectid,
3825					&disk_key, 0, l->start, 0);
3826	if (IS_ERR(right))
3827		return PTR_ERR(right);
3828
3829	root_add_used(root, root->leafsize);
3830
3831	memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
3832	btrfs_set_header_bytenr(right, right->start);
3833	btrfs_set_header_generation(right, trans->transid);
3834	btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
3835	btrfs_set_header_owner(right, root->root_key.objectid);
3836	btrfs_set_header_level(right, 0);
3837	write_extent_buffer(right, root->fs_info->fsid,
3838			    (unsigned long)btrfs_header_fsid(right),
3839			    BTRFS_FSID_SIZE);
3840
3841	write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
3842			    (unsigned long)btrfs_header_chunk_tree_uuid(right),
3843			    BTRFS_UUID_SIZE);
3844
3845	if (split == 0) {
3846		if (mid <= slot) {
3847			btrfs_set_header_nritems(right, 0);
3848			insert_ptr(trans, root, path, &disk_key, right->start,
3849				   path->slots[1] + 1, 1);
3850			btrfs_tree_unlock(path->nodes[0]);
3851			free_extent_buffer(path->nodes[0]);
3852			path->nodes[0] = right;
3853			path->slots[0] = 0;
3854			path->slots[1] += 1;
3855		} else {
3856			btrfs_set_header_nritems(right, 0);
3857			insert_ptr(trans, root, path, &disk_key, right->start,
3858					  path->slots[1], 1);
3859			btrfs_tree_unlock(path->nodes[0]);
3860			free_extent_buffer(path->nodes[0]);
3861			path->nodes[0] = right;
3862			path->slots[0] = 0;
3863			if (path->slots[1] == 0)
3864				fixup_low_keys(trans, root, path,
3865					       &disk_key, 1);
3866		}
3867		btrfs_mark_buffer_dirty(right);
 
 
 
 
3868		return ret;
3869	}
3870
3871	copy_for_split(trans, root, path, l, right, slot, mid, nritems);
3872
3873	if (split == 2) {
3874		BUG_ON(num_doubles != 0);
3875		num_doubles++;
3876		goto again;
3877	}
3878
3879	return 0;
3880
3881push_for_double:
3882	push_for_double_split(trans, root, path, data_size);
3883	tried_avoid_double = 1;
3884	if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
3885		return 0;
3886	goto again;
3887}
3888
3889static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3890					 struct btrfs_root *root,
3891					 struct btrfs_path *path, int ins_len)
3892{
 
3893	struct btrfs_key key;
3894	struct extent_buffer *leaf;
3895	struct btrfs_file_extent_item *fi;
3896	u64 extent_len = 0;
3897	u32 item_size;
3898	int ret;
3899
3900	leaf = path->nodes[0];
3901	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3902
3903	BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3904	       key.type != BTRFS_EXTENT_CSUM_KEY);
3905
3906	if (btrfs_leaf_free_space(root, leaf) >= ins_len)
3907		return 0;
3908
3909	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3910	if (key.type == BTRFS_EXTENT_DATA_KEY) {
3911		fi = btrfs_item_ptr(leaf, path->slots[0],
3912				    struct btrfs_file_extent_item);
3913		extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3914	}
3915	btrfs_release_path(path);
3916
3917	path->keep_locks = 1;
3918	path->search_for_split = 1;
3919	ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3920	path->search_for_split = 0;
 
 
3921	if (ret < 0)
3922		goto err;
3923
3924	ret = -EAGAIN;
3925	leaf = path->nodes[0];
3926	/* if our item isn't there or got smaller, return now */
3927	if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0]))
3928		goto err;
3929
3930	/* the leaf has  changed, it now has room.  return now */
3931	if (btrfs_leaf_free_space(root, path->nodes[0]) >= ins_len)
3932		goto err;
3933
3934	if (key.type == BTRFS_EXTENT_DATA_KEY) {
3935		fi = btrfs_item_ptr(leaf, path->slots[0],
3936				    struct btrfs_file_extent_item);
3937		if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3938			goto err;
3939	}
3940
3941	btrfs_set_path_blocking(path);
3942	ret = split_leaf(trans, root, &key, path, ins_len, 1);
3943	if (ret)
3944		goto err;
3945
3946	path->keep_locks = 0;
3947	btrfs_unlock_up_safe(path, 1);
3948	return 0;
3949err:
3950	path->keep_locks = 0;
3951	return ret;
3952}
3953
3954static noinline int split_item(struct btrfs_trans_handle *trans,
3955			       struct btrfs_root *root,
3956			       struct btrfs_path *path,
3957			       struct btrfs_key *new_key,
3958			       unsigned long split_offset)
3959{
3960	struct extent_buffer *leaf;
3961	struct btrfs_item *item;
3962	struct btrfs_item *new_item;
3963	int slot;
3964	char *buf;
3965	u32 nritems;
3966	u32 item_size;
3967	u32 orig_offset;
3968	struct btrfs_disk_key disk_key;
3969
3970	leaf = path->nodes[0];
3971	BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
3972
3973	btrfs_set_path_blocking(path);
3974
3975	item = btrfs_item_nr(leaf, path->slots[0]);
3976	orig_offset = btrfs_item_offset(leaf, item);
3977	item_size = btrfs_item_size(leaf, item);
3978
3979	buf = kmalloc(item_size, GFP_NOFS);
3980	if (!buf)
3981		return -ENOMEM;
3982
3983	read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3984			    path->slots[0]), item_size);
3985
3986	slot = path->slots[0] + 1;
3987	nritems = btrfs_header_nritems(leaf);
3988	if (slot != nritems) {
3989		/* shift the items */
3990		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
3991				btrfs_item_nr_offset(slot),
3992				(nritems - slot) * sizeof(struct btrfs_item));
3993	}
3994
3995	btrfs_cpu_key_to_disk(&disk_key, new_key);
3996	btrfs_set_item_key(leaf, &disk_key, slot);
3997
3998	new_item = btrfs_item_nr(leaf, slot);
3999
4000	btrfs_set_item_offset(leaf, new_item, orig_offset);
4001	btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4002
4003	btrfs_set_item_offset(leaf, item,
4004			      orig_offset + item_size - split_offset);
4005	btrfs_set_item_size(leaf, item, split_offset);
4006
4007	btrfs_set_header_nritems(leaf, nritems + 1);
4008
4009	/* write the data for the start of the original item */
4010	write_extent_buffer(leaf, buf,
4011			    btrfs_item_ptr_offset(leaf, path->slots[0]),
4012			    split_offset);
4013
4014	/* write the data for the new item */
4015	write_extent_buffer(leaf, buf + split_offset,
4016			    btrfs_item_ptr_offset(leaf, slot),
4017			    item_size - split_offset);
4018	btrfs_mark_buffer_dirty(leaf);
4019
4020	BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
4021	kfree(buf);
4022	return 0;
4023}
4024
4025/*
4026 * This function splits a single item into two items,
4027 * giving 'new_key' to the new item and splitting the
4028 * old one at split_offset (from the start of the item).
4029 *
4030 * The path may be released by this operation.  After
4031 * the split, the path is pointing to the old item.  The
4032 * new item is going to be in the same node as the old one.
4033 *
4034 * Note, the item being split must be smaller enough to live alone on
4035 * a tree block with room for one extra struct btrfs_item
4036 *
4037 * This allows us to split the item in place, keeping a lock on the
4038 * leaf the entire time.
4039 */
4040int btrfs_split_item(struct btrfs_trans_handle *trans,
4041		     struct btrfs_root *root,
4042		     struct btrfs_path *path,
4043		     struct btrfs_key *new_key,
4044		     unsigned long split_offset)
4045{
4046	int ret;
4047	ret = setup_leaf_for_split(trans, root, path,
4048				   sizeof(struct btrfs_item));
4049	if (ret)
4050		return ret;
4051
4052	ret = split_item(trans, root, path, new_key, split_offset);
4053	return ret;
4054}
4055
4056/*
4057 * This function duplicate a item, giving 'new_key' to the new item.
4058 * It guarantees both items live in the same tree leaf and the new item
4059 * is contiguous with the original item.
4060 *
4061 * This allows us to split file extent in place, keeping a lock on the
4062 * leaf the entire time.
4063 */
4064int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4065			 struct btrfs_root *root,
4066			 struct btrfs_path *path,
4067			 struct btrfs_key *new_key)
4068{
4069	struct extent_buffer *leaf;
4070	int ret;
4071	u32 item_size;
4072
4073	leaf = path->nodes[0];
4074	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4075	ret = setup_leaf_for_split(trans, root, path,
4076				   item_size + sizeof(struct btrfs_item));
4077	if (ret)
4078		return ret;
4079
4080	path->slots[0]++;
4081	setup_items_for_insert(trans, root, path, new_key, &item_size,
4082			       item_size, item_size +
4083			       sizeof(struct btrfs_item), 1);
4084	leaf = path->nodes[0];
4085	memcpy_extent_buffer(leaf,
4086			     btrfs_item_ptr_offset(leaf, path->slots[0]),
4087			     btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4088			     item_size);
4089	return 0;
4090}
4091
4092/*
4093 * make the item pointed to by the path smaller.  new_size indicates
4094 * how small to make it, and from_end tells us if we just chop bytes
4095 * off the end of the item or if we shift the item to chop bytes off
4096 * the front.
4097 */
4098void btrfs_truncate_item(struct btrfs_trans_handle *trans,
4099			 struct btrfs_root *root,
4100			 struct btrfs_path *path,
4101			 u32 new_size, int from_end)
4102{
4103	int slot;
4104	struct extent_buffer *leaf;
4105	struct btrfs_item *item;
4106	u32 nritems;
4107	unsigned int data_end;
4108	unsigned int old_data_start;
4109	unsigned int old_size;
4110	unsigned int size_diff;
4111	int i;
4112	struct btrfs_map_token token;
4113
4114	btrfs_init_map_token(&token);
4115
4116	leaf = path->nodes[0];
4117	slot = path->slots[0];
4118
4119	old_size = btrfs_item_size_nr(leaf, slot);
4120	if (old_size == new_size)
4121		return;
4122
4123	nritems = btrfs_header_nritems(leaf);
4124	data_end = leaf_data_end(root, leaf);
4125
4126	old_data_start = btrfs_item_offset_nr(leaf, slot);
4127
4128	size_diff = old_size - new_size;
4129
4130	BUG_ON(slot < 0);
4131	BUG_ON(slot >= nritems);
4132
4133	/*
4134	 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4135	 */
4136	/* first correct the data pointers */
4137	for (i = slot; i < nritems; i++) {
4138		u32 ioff;
4139		item = btrfs_item_nr(leaf, i);
4140
4141		ioff = btrfs_token_item_offset(leaf, item, &token);
4142		btrfs_set_token_item_offset(leaf, item,
4143					    ioff + size_diff, &token);
4144	}
4145
4146	/* shift the data */
4147	if (from_end) {
4148		memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4149			      data_end + size_diff, btrfs_leaf_data(leaf) +
4150			      data_end, old_data_start + new_size - data_end);
4151	} else {
4152		struct btrfs_disk_key disk_key;
4153		u64 offset;
4154
4155		btrfs_item_key(leaf, &disk_key, slot);
4156
4157		if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4158			unsigned long ptr;
4159			struct btrfs_file_extent_item *fi;
4160
4161			fi = btrfs_item_ptr(leaf, slot,
4162					    struct btrfs_file_extent_item);
4163			fi = (struct btrfs_file_extent_item *)(
4164			     (unsigned long)fi - size_diff);
4165
4166			if (btrfs_file_extent_type(leaf, fi) ==
4167			    BTRFS_FILE_EXTENT_INLINE) {
4168				ptr = btrfs_item_ptr_offset(leaf, slot);
4169				memmove_extent_buffer(leaf, ptr,
4170				      (unsigned long)fi,
4171				      offsetof(struct btrfs_file_extent_item,
4172						 disk_bytenr));
4173			}
4174		}
4175
4176		memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4177			      data_end + size_diff, btrfs_leaf_data(leaf) +
4178			      data_end, old_data_start - data_end);
4179
4180		offset = btrfs_disk_key_offset(&disk_key);
4181		btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4182		btrfs_set_item_key(leaf, &disk_key, slot);
4183		if (slot == 0)
4184			fixup_low_keys(trans, root, path, &disk_key, 1);
4185	}
4186
4187	item = btrfs_item_nr(leaf, slot);
4188	btrfs_set_item_size(leaf, item, new_size);
4189	btrfs_mark_buffer_dirty(leaf);
4190
4191	if (btrfs_leaf_free_space(root, leaf) < 0) {
4192		btrfs_print_leaf(root, leaf);
4193		BUG();
4194	}
4195}
4196
4197/*
4198 * make the item pointed to by the path bigger, data_size is the new size.
4199 */
4200void btrfs_extend_item(struct btrfs_trans_handle *trans,
4201		       struct btrfs_root *root, struct btrfs_path *path,
4202		       u32 data_size)
4203{
4204	int slot;
4205	struct extent_buffer *leaf;
4206	struct btrfs_item *item;
4207	u32 nritems;
4208	unsigned int data_end;
4209	unsigned int old_data;
4210	unsigned int old_size;
4211	int i;
4212	struct btrfs_map_token token;
4213
4214	btrfs_init_map_token(&token);
4215
4216	leaf = path->nodes[0];
4217
4218	nritems = btrfs_header_nritems(leaf);
4219	data_end = leaf_data_end(root, leaf);
4220
4221	if (btrfs_leaf_free_space(root, leaf) < data_size) {
4222		btrfs_print_leaf(root, leaf);
4223		BUG();
4224	}
4225	slot = path->slots[0];
4226	old_data = btrfs_item_end_nr(leaf, slot);
4227
4228	BUG_ON(slot < 0);
4229	if (slot >= nritems) {
4230		btrfs_print_leaf(root, leaf);
4231		printk(KERN_CRIT "slot %d too large, nritems %d\n",
4232		       slot, nritems);
4233		BUG_ON(1);
4234	}
4235
4236	/*
4237	 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4238	 */
4239	/* first correct the data pointers */
4240	for (i = slot; i < nritems; i++) {
4241		u32 ioff;
4242		item = btrfs_item_nr(leaf, i);
4243
4244		ioff = btrfs_token_item_offset(leaf, item, &token);
4245		btrfs_set_token_item_offset(leaf, item,
4246					    ioff - data_size, &token);
4247	}
4248
4249	/* shift the data */
4250	memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4251		      data_end - data_size, btrfs_leaf_data(leaf) +
4252		      data_end, old_data - data_end);
4253
4254	data_end = old_data;
4255	old_size = btrfs_item_size_nr(leaf, slot);
4256	item = btrfs_item_nr(leaf, slot);
4257	btrfs_set_item_size(leaf, item, old_size + data_size);
4258	btrfs_mark_buffer_dirty(leaf);
4259
4260	if (btrfs_leaf_free_space(root, leaf) < 0) {
4261		btrfs_print_leaf(root, leaf);
4262		BUG();
4263	}
4264}
4265
4266/*
4267 * Given a key and some data, insert items into the tree.
4268 * This does all the path init required, making room in the tree if needed.
4269 * Returns the number of keys that were inserted.
4270 */
4271int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
4272			    struct btrfs_root *root,
4273			    struct btrfs_path *path,
4274			    struct btrfs_key *cpu_key, u32 *data_size,
4275			    int nr)
4276{
4277	struct extent_buffer *leaf;
4278	struct btrfs_item *item;
4279	int ret = 0;
4280	int slot;
4281	int i;
4282	u32 nritems;
4283	u32 total_data = 0;
4284	u32 total_size = 0;
4285	unsigned int data_end;
4286	struct btrfs_disk_key disk_key;
4287	struct btrfs_key found_key;
4288	struct btrfs_map_token token;
4289
4290	btrfs_init_map_token(&token);
4291
4292	for (i = 0; i < nr; i++) {
4293		if (total_size + data_size[i] + sizeof(struct btrfs_item) >
4294		    BTRFS_LEAF_DATA_SIZE(root)) {
4295			break;
4296			nr = i;
4297		}
4298		total_data += data_size[i];
4299		total_size += data_size[i] + sizeof(struct btrfs_item);
4300	}
4301	BUG_ON(nr == 0);
4302
4303	ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4304	if (ret == 0)
4305		return -EEXIST;
4306	if (ret < 0)
4307		goto out;
4308
4309	leaf = path->nodes[0];
4310
4311	nritems = btrfs_header_nritems(leaf);
4312	data_end = leaf_data_end(root, leaf);
4313
4314	if (btrfs_leaf_free_space(root, leaf) < total_size) {
4315		for (i = nr; i >= 0; i--) {
4316			total_data -= data_size[i];
4317			total_size -= data_size[i] + sizeof(struct btrfs_item);
4318			if (total_size < btrfs_leaf_free_space(root, leaf))
4319				break;
4320		}
4321		nr = i;
4322	}
4323
4324	slot = path->slots[0];
4325	BUG_ON(slot < 0);
4326
4327	if (slot != nritems) {
4328		unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4329
4330		item = btrfs_item_nr(leaf, slot);
4331		btrfs_item_key_to_cpu(leaf, &found_key, slot);
4332
4333		/* figure out how many keys we can insert in here */
4334		total_data = data_size[0];
4335		for (i = 1; i < nr; i++) {
4336			if (btrfs_comp_cpu_keys(&found_key, cpu_key + i) <= 0)
4337				break;
4338			total_data += data_size[i];
4339		}
4340		nr = i;
4341
4342		if (old_data < data_end) {
4343			btrfs_print_leaf(root, leaf);
4344			printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
4345			       slot, old_data, data_end);
4346			BUG_ON(1);
4347		}
4348		/*
4349		 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4350		 */
4351		/* first correct the data pointers */
4352		for (i = slot; i < nritems; i++) {
4353			u32 ioff;
4354
4355			item = btrfs_item_nr(leaf, i);
4356			ioff = btrfs_token_item_offset(leaf, item, &token);
4357			btrfs_set_token_item_offset(leaf, item,
4358						    ioff - total_data, &token);
4359		}
4360		/* shift the items */
4361		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4362			      btrfs_item_nr_offset(slot),
4363			      (nritems - slot) * sizeof(struct btrfs_item));
4364
4365		/* shift the data */
4366		memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4367			      data_end - total_data, btrfs_leaf_data(leaf) +
4368			      data_end, old_data - data_end);
4369		data_end = old_data;
4370	} else {
4371		/*
4372		 * this sucks but it has to be done, if we are inserting at
4373		 * the end of the leaf only insert 1 of the items, since we
4374		 * have no way of knowing whats on the next leaf and we'd have
4375		 * to drop our current locks to figure it out
4376		 */
4377		nr = 1;
4378	}
4379
4380	/* setup the item for the new data */
4381	for (i = 0; i < nr; i++) {
4382		btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4383		btrfs_set_item_key(leaf, &disk_key, slot + i);
4384		item = btrfs_item_nr(leaf, slot + i);
4385		btrfs_set_token_item_offset(leaf, item,
4386					    data_end - data_size[i], &token);
4387		data_end -= data_size[i];
4388		btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4389	}
4390	btrfs_set_header_nritems(leaf, nritems + nr);
4391	btrfs_mark_buffer_dirty(leaf);
4392
4393	ret = 0;
4394	if (slot == 0) {
4395		btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4396		fixup_low_keys(trans, root, path, &disk_key, 1);
4397	}
4398
4399	if (btrfs_leaf_free_space(root, leaf) < 0) {
4400		btrfs_print_leaf(root, leaf);
4401		BUG();
4402	}
4403out:
4404	if (!ret)
4405		ret = nr;
4406	return ret;
4407}
4408
4409/*
4410 * this is a helper for btrfs_insert_empty_items, the main goal here is
4411 * to save stack depth by doing the bulk of the work in a function
4412 * that doesn't call btrfs_search_slot
4413 */
4414void setup_items_for_insert(struct btrfs_trans_handle *trans,
4415			    struct btrfs_root *root, struct btrfs_path *path,
4416			    struct btrfs_key *cpu_key, u32 *data_size,
4417			    u32 total_data, u32 total_size, int nr)
4418{
 
4419	struct btrfs_item *item;
4420	int i;
4421	u32 nritems;
4422	unsigned int data_end;
4423	struct btrfs_disk_key disk_key;
4424	struct extent_buffer *leaf;
4425	int slot;
4426	struct btrfs_map_token token;
4427
 
 
 
 
 
 
4428	btrfs_init_map_token(&token);
4429
4430	leaf = path->nodes[0];
4431	slot = path->slots[0];
4432
4433	nritems = btrfs_header_nritems(leaf);
4434	data_end = leaf_data_end(root, leaf);
4435
4436	if (btrfs_leaf_free_space(root, leaf) < total_size) {
4437		btrfs_print_leaf(root, leaf);
4438		printk(KERN_CRIT "not enough freespace need %u have %d\n",
4439		       total_size, btrfs_leaf_free_space(root, leaf));
4440		BUG();
4441	}
4442
4443	if (slot != nritems) {
4444		unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4445
4446		if (old_data < data_end) {
4447			btrfs_print_leaf(root, leaf);
4448			printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
4449			       slot, old_data, data_end);
4450			BUG_ON(1);
4451		}
4452		/*
4453		 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4454		 */
4455		/* first correct the data pointers */
4456		for (i = slot; i < nritems; i++) {
4457			u32 ioff;
4458
4459			item = btrfs_item_nr(leaf, i);
4460			ioff = btrfs_token_item_offset(leaf, item, &token);
4461			btrfs_set_token_item_offset(leaf, item,
4462						    ioff - total_data, &token);
4463		}
4464		/* shift the items */
4465		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4466			      btrfs_item_nr_offset(slot),
4467			      (nritems - slot) * sizeof(struct btrfs_item));
4468
4469		/* shift the data */
4470		memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4471			      data_end - total_data, btrfs_leaf_data(leaf) +
4472			      data_end, old_data - data_end);
4473		data_end = old_data;
4474	}
4475
4476	/* setup the item for the new data */
4477	for (i = 0; i < nr; i++) {
4478		btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4479		btrfs_set_item_key(leaf, &disk_key, slot + i);
4480		item = btrfs_item_nr(leaf, slot + i);
4481		btrfs_set_token_item_offset(leaf, item,
4482					    data_end - data_size[i], &token);
4483		data_end -= data_size[i];
4484		btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4485	}
4486
4487	btrfs_set_header_nritems(leaf, nritems + nr);
4488
4489	if (slot == 0) {
4490		btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4491		fixup_low_keys(trans, root, path, &disk_key, 1);
4492	}
4493	btrfs_unlock_up_safe(path, 1);
4494	btrfs_mark_buffer_dirty(leaf);
4495
4496	if (btrfs_leaf_free_space(root, leaf) < 0) {
4497		btrfs_print_leaf(root, leaf);
4498		BUG();
4499	}
4500}
4501
4502/*
4503 * Given a key and some data, insert items into the tree.
4504 * This does all the path init required, making room in the tree if needed.
4505 */
4506int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4507			    struct btrfs_root *root,
4508			    struct btrfs_path *path,
4509			    struct btrfs_key *cpu_key, u32 *data_size,
4510			    int nr)
4511{
4512	int ret = 0;
4513	int slot;
4514	int i;
4515	u32 total_size = 0;
4516	u32 total_data = 0;
4517
4518	for (i = 0; i < nr; i++)
4519		total_data += data_size[i];
4520
4521	total_size = total_data + (nr * sizeof(struct btrfs_item));
4522	ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4523	if (ret == 0)
4524		return -EEXIST;
4525	if (ret < 0)
4526		return ret;
4527
4528	slot = path->slots[0];
4529	BUG_ON(slot < 0);
4530
4531	setup_items_for_insert(trans, root, path, cpu_key, data_size,
4532			       total_data, total_size, nr);
4533	return 0;
4534}
4535
4536/*
4537 * Given a key and some data, insert an item into the tree.
4538 * This does all the path init required, making room in the tree if needed.
4539 */
4540int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
4541		      *root, struct btrfs_key *cpu_key, void *data, u32
4542		      data_size)
4543{
4544	int ret = 0;
4545	struct btrfs_path *path;
4546	struct extent_buffer *leaf;
4547	unsigned long ptr;
4548
4549	path = btrfs_alloc_path();
4550	if (!path)
4551		return -ENOMEM;
4552	ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4553	if (!ret) {
4554		leaf = path->nodes[0];
4555		ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4556		write_extent_buffer(leaf, data, ptr, data_size);
4557		btrfs_mark_buffer_dirty(leaf);
4558	}
4559	btrfs_free_path(path);
4560	return ret;
4561}
4562
4563/*
4564 * delete the pointer from a given node.
4565 *
4566 * the tree should have been previously balanced so the deletion does not
4567 * empty a node.
4568 */
4569static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4570		    struct btrfs_path *path, int level, int slot,
4571		    int tree_mod_log)
4572{
 
4573	struct extent_buffer *parent = path->nodes[level];
4574	u32 nritems;
4575	int ret;
4576
4577	nritems = btrfs_header_nritems(parent);
4578	if (slot != nritems - 1) {
4579		if (tree_mod_log && level)
4580			tree_mod_log_eb_move(root->fs_info, parent, slot,
4581					     slot + 1, nritems - slot - 1);
4582		memmove_extent_buffer(parent,
4583			      btrfs_node_key_ptr_offset(slot),
4584			      btrfs_node_key_ptr_offset(slot + 1),
4585			      sizeof(struct btrfs_key_ptr) *
4586			      (nritems - slot - 1));
4587	} else if (tree_mod_log && level) {
4588		ret = tree_mod_log_insert_key(root->fs_info, parent, slot,
4589					      MOD_LOG_KEY_REMOVE);
4590		BUG_ON(ret < 0);
4591	}
4592
4593	nritems--;
4594	btrfs_set_header_nritems(parent, nritems);
4595	if (nritems == 0 && parent == root->node) {
4596		BUG_ON(btrfs_header_level(root->node) != 1);
4597		/* just turn the root into a leaf and break */
4598		btrfs_set_header_level(root->node, 0);
4599	} else if (slot == 0) {
4600		struct btrfs_disk_key disk_key;
4601
4602		btrfs_node_key(parent, &disk_key, 0);
4603		fixup_low_keys(trans, root, path, &disk_key, level + 1);
4604	}
4605	btrfs_mark_buffer_dirty(parent);
4606}
4607
4608/*
4609 * a helper function to delete the leaf pointed to by path->slots[1] and
4610 * path->nodes[1].
4611 *
4612 * This deletes the pointer in path->nodes[1] and frees the leaf
4613 * block extent.  zero is returned if it all worked out, < 0 otherwise.
4614 *
4615 * The path must have already been setup for deleting the leaf, including
4616 * all the proper balancing.  path->nodes[1] must be locked.
4617 */
4618static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4619				    struct btrfs_root *root,
4620				    struct btrfs_path *path,
4621				    struct extent_buffer *leaf)
4622{
4623	WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4624	del_ptr(trans, root, path, 1, path->slots[1], 1);
4625
4626	/*
4627	 * btrfs_free_extent is expensive, we want to make sure we
4628	 * aren't holding any locks when we call it
4629	 */
4630	btrfs_unlock_up_safe(path, 0);
4631
4632	root_sub_used(root, leaf->len);
4633
4634	extent_buffer_get(leaf);
4635	btrfs_free_tree_block(trans, root, leaf, 0, 1);
4636	free_extent_buffer_stale(leaf);
4637}
4638/*
4639 * delete the item at the leaf level in path.  If that empties
4640 * the leaf, remove it from the tree
4641 */
4642int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4643		    struct btrfs_path *path, int slot, int nr)
4644{
 
4645	struct extent_buffer *leaf;
4646	struct btrfs_item *item;
4647	int last_off;
4648	int dsize = 0;
4649	int ret = 0;
4650	int wret;
4651	int i;
4652	u32 nritems;
4653	struct btrfs_map_token token;
4654
4655	btrfs_init_map_token(&token);
4656
4657	leaf = path->nodes[0];
4658	last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4659
4660	for (i = 0; i < nr; i++)
4661		dsize += btrfs_item_size_nr(leaf, slot + i);
4662
4663	nritems = btrfs_header_nritems(leaf);
4664
4665	if (slot + nr != nritems) {
4666		int data_end = leaf_data_end(root, leaf);
4667
4668		memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4669			      data_end + dsize,
4670			      btrfs_leaf_data(leaf) + data_end,
4671			      last_off - data_end);
4672
4673		for (i = slot + nr; i < nritems; i++) {
4674			u32 ioff;
4675
4676			item = btrfs_item_nr(leaf, i);
4677			ioff = btrfs_token_item_offset(leaf, item, &token);
4678			btrfs_set_token_item_offset(leaf, item,
4679						    ioff + dsize, &token);
4680		}
4681
4682		memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4683			      btrfs_item_nr_offset(slot + nr),
4684			      sizeof(struct btrfs_item) *
4685			      (nritems - slot - nr));
4686	}
4687	btrfs_set_header_nritems(leaf, nritems - nr);
4688	nritems -= nr;
4689
4690	/* delete the leaf if we've emptied it */
4691	if (nritems == 0) {
4692		if (leaf == root->node) {
4693			btrfs_set_header_level(leaf, 0);
4694		} else {
4695			btrfs_set_path_blocking(path);
4696			clean_tree_block(trans, root, leaf);
4697			btrfs_del_leaf(trans, root, path, leaf);
4698		}
4699	} else {
4700		int used = leaf_space_used(leaf, 0, nritems);
4701		if (slot == 0) {
4702			struct btrfs_disk_key disk_key;
4703
4704			btrfs_item_key(leaf, &disk_key, 0);
4705			fixup_low_keys(trans, root, path, &disk_key, 1);
4706		}
4707
4708		/* delete the leaf if it is mostly empty */
4709		if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
4710			/* push_leaf_left fixes the path.
4711			 * make sure the path still points to our leaf
4712			 * for possible call to del_ptr below
4713			 */
4714			slot = path->slots[1];
4715			extent_buffer_get(leaf);
4716
4717			btrfs_set_path_blocking(path);
4718			wret = push_leaf_left(trans, root, path, 1, 1,
4719					      1, (u32)-1);
4720			if (wret < 0 && wret != -ENOSPC)
4721				ret = wret;
4722
4723			if (path->nodes[0] == leaf &&
4724			    btrfs_header_nritems(leaf)) {
4725				wret = push_leaf_right(trans, root, path, 1,
4726						       1, 1, 0);
4727				if (wret < 0 && wret != -ENOSPC)
4728					ret = wret;
4729			}
4730
4731			if (btrfs_header_nritems(leaf) == 0) {
4732				path->slots[1] = slot;
4733				btrfs_del_leaf(trans, root, path, leaf);
4734				free_extent_buffer(leaf);
4735				ret = 0;
4736			} else {
4737				/* if we're still in the path, make sure
4738				 * we're dirty.  Otherwise, one of the
4739				 * push_leaf functions must have already
4740				 * dirtied this buffer
4741				 */
4742				if (path->nodes[0] == leaf)
4743					btrfs_mark_buffer_dirty(leaf);
4744				free_extent_buffer(leaf);
4745			}
4746		} else {
4747			btrfs_mark_buffer_dirty(leaf);
4748		}
4749	}
4750	return ret;
4751}
4752
4753/*
4754 * search the tree again to find a leaf with lesser keys
4755 * returns 0 if it found something or 1 if there are no lesser leaves.
4756 * returns < 0 on io errors.
4757 *
4758 * This may release the path, and so you may lose any locks held at the
4759 * time you call it.
4760 */
4761int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
4762{
4763	struct btrfs_key key;
4764	struct btrfs_disk_key found_key;
4765	int ret;
4766
4767	btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
4768
4769	if (key.offset > 0)
4770		key.offset--;
4771	else if (key.type > 0)
4772		key.type--;
4773	else if (key.objectid > 0)
 
4774		key.objectid--;
4775	else
 
 
4776		return 1;
 
4777
4778	btrfs_release_path(path);
4779	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4780	if (ret < 0)
4781		return ret;
4782	btrfs_item_key(path->nodes[0], &found_key, 0);
4783	ret = comp_keys(&found_key, &key);
4784	if (ret < 0)
 
 
 
 
 
 
 
 
 
 
4785		return 0;
4786	return 1;
4787}
4788
4789/*
4790 * A helper function to walk down the tree starting at min_key, and looking
4791 * for nodes or leaves that are either in cache or have a minimum
4792 * transaction id.  This is used by the btree defrag code, and tree logging
4793 *
4794 * This does not cow, but it does stuff the starting key it finds back
4795 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4796 * key and get a writable path.
4797 *
4798 * This does lock as it descends, and path->keep_locks should be set
4799 * to 1 by the caller.
4800 *
4801 * This honors path->lowest_level to prevent descent past a given level
4802 * of the tree.
4803 *
4804 * min_trans indicates the oldest transaction that you are interested
4805 * in walking through.  Any nodes or leaves older than min_trans are
4806 * skipped over (without reading them).
4807 *
4808 * returns zero if something useful was found, < 0 on error and 1 if there
4809 * was nothing in the tree that matched the search criteria.
4810 */
4811int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4812			 struct btrfs_key *max_key,
4813			 struct btrfs_path *path, int cache_only,
4814			 u64 min_trans)
4815{
 
4816	struct extent_buffer *cur;
4817	struct btrfs_key found_key;
4818	int slot;
4819	int sret;
4820	u32 nritems;
4821	int level;
4822	int ret = 1;
 
4823
4824	WARN_ON(!path->keep_locks);
4825again:
4826	cur = btrfs_read_lock_root_node(root);
4827	level = btrfs_header_level(cur);
4828	WARN_ON(path->nodes[level]);
4829	path->nodes[level] = cur;
4830	path->locks[level] = BTRFS_READ_LOCK;
4831
4832	if (btrfs_header_generation(cur) < min_trans) {
4833		ret = 1;
4834		goto out;
4835	}
4836	while (1) {
4837		nritems = btrfs_header_nritems(cur);
4838		level = btrfs_header_level(cur);
4839		sret = bin_search(cur, min_key, level, &slot);
4840
4841		/* at the lowest level, we're done, setup the path and exit */
4842		if (level == path->lowest_level) {
4843			if (slot >= nritems)
4844				goto find_next_key;
4845			ret = 0;
4846			path->slots[level] = slot;
4847			btrfs_item_key_to_cpu(cur, &found_key, slot);
4848			goto out;
4849		}
4850		if (sret && slot > 0)
4851			slot--;
4852		/*
4853		 * check this node pointer against the cache_only and
4854		 * min_trans parameters.  If it isn't in cache or is too
4855		 * old, skip to the next one.
4856		 */
4857		while (slot < nritems) {
4858			u64 blockptr;
4859			u64 gen;
4860			struct extent_buffer *tmp;
4861			struct btrfs_disk_key disk_key;
4862
4863			blockptr = btrfs_node_blockptr(cur, slot);
4864			gen = btrfs_node_ptr_generation(cur, slot);
4865			if (gen < min_trans) {
4866				slot++;
4867				continue;
4868			}
4869			if (!cache_only)
4870				break;
4871
4872			if (max_key) {
4873				btrfs_node_key(cur, &disk_key, slot);
4874				if (comp_keys(&disk_key, max_key) >= 0) {
4875					ret = 1;
4876					goto out;
4877				}
4878			}
4879
4880			tmp = btrfs_find_tree_block(root, blockptr,
4881					    btrfs_level_size(root, level - 1));
4882
4883			if (tmp && btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
4884				free_extent_buffer(tmp);
4885				break;
4886			}
4887			if (tmp)
4888				free_extent_buffer(tmp);
4889			slot++;
4890		}
4891find_next_key:
4892		/*
4893		 * we didn't find a candidate key in this node, walk forward
4894		 * and find another one
4895		 */
4896		if (slot >= nritems) {
4897			path->slots[level] = slot;
4898			btrfs_set_path_blocking(path);
4899			sret = btrfs_find_next_key(root, path, min_key, level,
4900						  cache_only, min_trans);
4901			if (sret == 0) {
4902				btrfs_release_path(path);
4903				goto again;
4904			} else {
4905				goto out;
4906			}
4907		}
4908		/* save our key for returning back */
4909		btrfs_node_key_to_cpu(cur, &found_key, slot);
4910		path->slots[level] = slot;
4911		if (level == path->lowest_level) {
4912			ret = 0;
4913			unlock_up(path, level, 1, 0, NULL);
4914			goto out;
4915		}
4916		btrfs_set_path_blocking(path);
4917		cur = read_node_slot(root, cur, slot);
4918		BUG_ON(!cur); /* -ENOMEM */
 
 
 
4919
4920		btrfs_tree_read_lock(cur);
4921
4922		path->locks[level - 1] = BTRFS_READ_LOCK;
4923		path->nodes[level - 1] = cur;
4924		unlock_up(path, level, 1, 0, NULL);
4925		btrfs_clear_path_blocking(path, NULL, 0);
4926	}
4927out:
4928	if (ret == 0)
 
 
 
4929		memcpy(min_key, &found_key, sizeof(found_key));
4930	btrfs_set_path_blocking(path);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4931	return ret;
4932}
4933
4934/*
4935 * this is similar to btrfs_next_leaf, but does not try to preserve
4936 * and fixup the path.  It looks for and returns the next key in the
4937 * tree based on the current path and the cache_only and min_trans
4938 * parameters.
4939 *
4940 * 0 is returned if another key is found, < 0 if there are any errors
4941 * and 1 is returned if there are no higher keys in the tree
4942 *
4943 * path->keep_locks should be set to 1 on the search made before
4944 * calling this function.
4945 */
4946int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4947			struct btrfs_key *key, int level,
4948			int cache_only, u64 min_trans)
4949{
4950	int slot;
4951	struct extent_buffer *c;
4952
4953	WARN_ON(!path->keep_locks);
4954	while (level < BTRFS_MAX_LEVEL) {
4955		if (!path->nodes[level])
4956			return 1;
4957
4958		slot = path->slots[level] + 1;
4959		c = path->nodes[level];
4960next:
4961		if (slot >= btrfs_header_nritems(c)) {
4962			int ret;
4963			int orig_lowest;
4964			struct btrfs_key cur_key;
4965			if (level + 1 >= BTRFS_MAX_LEVEL ||
4966			    !path->nodes[level + 1])
4967				return 1;
4968
4969			if (path->locks[level + 1]) {
4970				level++;
4971				continue;
4972			}
4973
4974			slot = btrfs_header_nritems(c) - 1;
4975			if (level == 0)
4976				btrfs_item_key_to_cpu(c, &cur_key, slot);
4977			else
4978				btrfs_node_key_to_cpu(c, &cur_key, slot);
4979
4980			orig_lowest = path->lowest_level;
4981			btrfs_release_path(path);
4982			path->lowest_level = level;
4983			ret = btrfs_search_slot(NULL, root, &cur_key, path,
4984						0, 0);
4985			path->lowest_level = orig_lowest;
4986			if (ret < 0)
4987				return ret;
4988
4989			c = path->nodes[level];
4990			slot = path->slots[level];
4991			if (ret == 0)
4992				slot++;
4993			goto next;
4994		}
4995
4996		if (level == 0)
4997			btrfs_item_key_to_cpu(c, key, slot);
4998		else {
4999			u64 blockptr = btrfs_node_blockptr(c, slot);
5000			u64 gen = btrfs_node_ptr_generation(c, slot);
5001
5002			if (cache_only) {
5003				struct extent_buffer *cur;
5004				cur = btrfs_find_tree_block(root, blockptr,
5005					    btrfs_level_size(root, level - 1));
5006				if (!cur ||
5007				    btrfs_buffer_uptodate(cur, gen, 1) <= 0) {
5008					slot++;
5009					if (cur)
5010						free_extent_buffer(cur);
5011					goto next;
5012				}
5013				free_extent_buffer(cur);
5014			}
5015			if (gen < min_trans) {
5016				slot++;
5017				goto next;
5018			}
5019			btrfs_node_key_to_cpu(c, key, slot);
5020		}
5021		return 0;
5022	}
5023	return 1;
5024}
5025
5026/*
5027 * search the tree again to find a leaf with greater keys
5028 * returns 0 if it found something or 1 if there are no greater leaves.
5029 * returns < 0 on io errors.
5030 */
5031int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5032{
5033	return btrfs_next_old_leaf(root, path, 0);
5034}
5035
5036int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5037			u64 time_seq)
5038{
5039	int slot;
5040	int level;
5041	struct extent_buffer *c;
5042	struct extent_buffer *next;
5043	struct btrfs_key key;
5044	u32 nritems;
5045	int ret;
5046	int old_spinning = path->leave_spinning;
5047	int next_rw_lock = 0;
5048
5049	nritems = btrfs_header_nritems(path->nodes[0]);
5050	if (nritems == 0)
5051		return 1;
5052
5053	btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5054again:
5055	level = 1;
5056	next = NULL;
5057	next_rw_lock = 0;
5058	btrfs_release_path(path);
5059
5060	path->keep_locks = 1;
5061	path->leave_spinning = 1;
5062
5063	if (time_seq)
5064		ret = btrfs_search_old_slot(root, &key, path, time_seq);
5065	else
5066		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5067	path->keep_locks = 0;
5068
5069	if (ret < 0)
5070		return ret;
5071
5072	nritems = btrfs_header_nritems(path->nodes[0]);
5073	/*
5074	 * by releasing the path above we dropped all our locks.  A balance
5075	 * could have added more items next to the key that used to be
5076	 * at the very end of the block.  So, check again here and
5077	 * advance the path if there are now more items available.
5078	 */
5079	if (nritems > 0 && path->slots[0] < nritems - 1) {
5080		if (ret == 0)
5081			path->slots[0]++;
5082		ret = 0;
5083		goto done;
5084	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5085
5086	while (level < BTRFS_MAX_LEVEL) {
5087		if (!path->nodes[level]) {
5088			ret = 1;
5089			goto done;
5090		}
5091
5092		slot = path->slots[level] + 1;
5093		c = path->nodes[level];
5094		if (slot >= btrfs_header_nritems(c)) {
5095			level++;
5096			if (level == BTRFS_MAX_LEVEL) {
5097				ret = 1;
5098				goto done;
5099			}
5100			continue;
5101		}
5102
5103		if (next) {
5104			btrfs_tree_unlock_rw(next, next_rw_lock);
5105			free_extent_buffer(next);
5106		}
5107
5108		next = c;
5109		next_rw_lock = path->locks[level];
5110		ret = read_block_for_search(NULL, root, path, &next, level,
5111					    slot, &key, 0);
5112		if (ret == -EAGAIN)
5113			goto again;
5114
5115		if (ret < 0) {
5116			btrfs_release_path(path);
5117			goto done;
5118		}
5119
5120		if (!path->skip_locking) {
5121			ret = btrfs_try_tree_read_lock(next);
5122			if (!ret && time_seq) {
5123				/*
5124				 * If we don't get the lock, we may be racing
5125				 * with push_leaf_left, holding that lock while
5126				 * itself waiting for the leaf we've currently
5127				 * locked. To solve this situation, we give up
5128				 * on our lock and cycle.
5129				 */
 
5130				btrfs_release_path(path);
5131				cond_resched();
5132				goto again;
5133			}
5134			if (!ret) {
5135				btrfs_set_path_blocking(path);
5136				btrfs_tree_read_lock(next);
5137				btrfs_clear_path_blocking(path, next,
5138							  BTRFS_READ_LOCK);
5139			}
5140			next_rw_lock = BTRFS_READ_LOCK;
5141		}
5142		break;
5143	}
5144	path->slots[level] = slot;
5145	while (1) {
5146		level--;
5147		c = path->nodes[level];
5148		if (path->locks[level])
5149			btrfs_tree_unlock_rw(c, path->locks[level]);
5150
5151		free_extent_buffer(c);
5152		path->nodes[level] = next;
5153		path->slots[level] = 0;
5154		if (!path->skip_locking)
5155			path->locks[level] = next_rw_lock;
5156		if (!level)
5157			break;
5158
5159		ret = read_block_for_search(NULL, root, path, &next, level,
5160					    0, &key, 0);
5161		if (ret == -EAGAIN)
5162			goto again;
5163
5164		if (ret < 0) {
5165			btrfs_release_path(path);
5166			goto done;
5167		}
5168
5169		if (!path->skip_locking) {
5170			ret = btrfs_try_tree_read_lock(next);
5171			if (!ret) {
5172				btrfs_set_path_blocking(path);
5173				btrfs_tree_read_lock(next);
5174				btrfs_clear_path_blocking(path, next,
5175							  BTRFS_READ_LOCK);
5176			}
5177			next_rw_lock = BTRFS_READ_LOCK;
5178		}
5179	}
5180	ret = 0;
5181done:
5182	unlock_up(path, 0, 1, 0, NULL);
5183	path->leave_spinning = old_spinning;
5184	if (!old_spinning)
5185		btrfs_set_path_blocking(path);
5186
5187	return ret;
5188}
5189
5190/*
5191 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5192 * searching until it gets past min_objectid or finds an item of 'type'
5193 *
5194 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5195 */
5196int btrfs_previous_item(struct btrfs_root *root,
5197			struct btrfs_path *path, u64 min_objectid,
5198			int type)
5199{
5200	struct btrfs_key found_key;
5201	struct extent_buffer *leaf;
5202	u32 nritems;
5203	int ret;
5204
5205	while (1) {
5206		if (path->slots[0] == 0) {
5207			btrfs_set_path_blocking(path);
5208			ret = btrfs_prev_leaf(root, path);
5209			if (ret != 0)
5210				return ret;
5211		} else {
5212			path->slots[0]--;
5213		}
5214		leaf = path->nodes[0];
5215		nritems = btrfs_header_nritems(leaf);
5216		if (nritems == 0)
5217			return 1;
5218		if (path->slots[0] == nritems)
5219			path->slots[0]--;
5220
5221		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5222		if (found_key.objectid < min_objectid)
5223			break;
5224		if (found_key.type == type)
5225			return 0;
5226		if (found_key.objectid == min_objectid &&
5227		    found_key.type < type)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5228			break;
5229	}
5230	return 1;
5231}