1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2007,2008 Oracle.  All rights reserved.
   4 */
   5
   6#include <linux/sched.h>
   7#include <linux/slab.h>
   8#include <linux/rbtree.h>
   9#include <linux/mm.h>
  10#include <linux/error-injection.h>
  11#include "messages.h"
  12#include "ctree.h"
  13#include "disk-io.h"
  14#include "transaction.h"
  15#include "print-tree.h"
  16#include "locking.h"
  17#include "volumes.h"
  18#include "qgroup.h"
  19#include "tree-mod-log.h"
  20#include "tree-checker.h"
  21#include "fs.h"
  22#include "accessors.h"
  23#include "extent-tree.h"
  24#include "relocation.h"
  25#include "file-item.h"
  26
  27static struct kmem_cache *btrfs_path_cachep;
  28
  29static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  30		      *root, struct btrfs_path *path, int level);
  31static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  32		      const struct btrfs_key *ins_key, struct btrfs_path *path,
  33		      int data_size, int extend);
  34static int push_node_left(struct btrfs_trans_handle *trans,
 
  35			  struct extent_buffer *dst,
  36			  struct extent_buffer *src, int empty);
  37static int balance_node_right(struct btrfs_trans_handle *trans,
 
  38			      struct extent_buffer *dst_buf,
  39			      struct extent_buffer *src_buf);
 
 
  40
  41static const struct btrfs_csums {
  42	u16		size;
  43	const char	name[10];
  44	const char	driver[12];
  45} btrfs_csums[] = {
  46	[BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
  47	[BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
  48	[BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
  49	[BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
  50				     .driver = "blake2b-256" },
  51};
  52
  53/*
  54 * The leaf data grows from end-to-front in the node.  this returns the address
  55 * of the start of the last item, which is the stop of the leaf data stack.
  56 */
  57static unsigned int leaf_data_end(const struct extent_buffer *leaf)
  58{
  59	u32 nr = btrfs_header_nritems(leaf);
  60
  61	if (nr == 0)
  62		return BTRFS_LEAF_DATA_SIZE(leaf->fs_info);
  63	return btrfs_item_offset(leaf, nr - 1);
  64}
  65
  66/*
  67 * Move data in a @leaf (using memmove, safe for overlapping ranges).
  68 *
  69 * @leaf:	leaf that we're doing a memmove on
  70 * @dst_offset:	item data offset we're moving to
  71 * @src_offset:	item data offset were' moving from
  72 * @len:	length of the data we're moving
  73 *
  74 * Wrapper around memmove_extent_buffer() that takes into account the header on
  75 * the leaf.  The btrfs_item offset's start directly after the header, so we
  76 * have to adjust any offsets to account for the header in the leaf.  This
  77 * handles that math to simplify the callers.
  78 */
  79static inline void memmove_leaf_data(const struct extent_buffer *leaf,
  80				     unsigned long dst_offset,
  81				     unsigned long src_offset,
  82				     unsigned long len)
  83{
  84	memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, 0) + dst_offset,
  85			      btrfs_item_nr_offset(leaf, 0) + src_offset, len);
  86}
  87
  88/*
  89 * Copy item data from @src into @dst at the given @offset.
  90 *
  91 * @dst:	destination leaf that we're copying into
  92 * @src:	source leaf that we're copying from
  93 * @dst_offset:	item data offset we're copying to
  94 * @src_offset:	item data offset were' copying from
  95 * @len:	length of the data we're copying
  96 *
  97 * Wrapper around copy_extent_buffer() that takes into account the header on
  98 * the leaf.  The btrfs_item offset's start directly after the header, so we
  99 * have to adjust any offsets to account for the header in the leaf.  This
 100 * handles that math to simplify the callers.
 101 */
 102static inline void copy_leaf_data(const struct extent_buffer *dst,
 103				  const struct extent_buffer *src,
 104				  unsigned long dst_offset,
 105				  unsigned long src_offset, unsigned long len)
 106{
 107	copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, 0) + dst_offset,
 108			   btrfs_item_nr_offset(src, 0) + src_offset, len);
 109}
 110
 111/*
 112 * Move items in a @leaf (using memmove).
 113 *
 114 * @dst:	destination leaf for the items
 115 * @dst_item:	the item nr we're copying into
 116 * @src_item:	the item nr we're copying from
 117 * @nr_items:	the number of items to copy
 118 *
 119 * Wrapper around memmove_extent_buffer() that does the math to get the
 120 * appropriate offsets into the leaf from the item numbers.
 121 */
 122static inline void memmove_leaf_items(const struct extent_buffer *leaf,
 123				      int dst_item, int src_item, int nr_items)
 124{
 125	memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, dst_item),
 126			      btrfs_item_nr_offset(leaf, src_item),
 127			      nr_items * sizeof(struct btrfs_item));
 
 
 
 
 
 
 
 128}
 129
 130/*
 131 * Copy items from @src into @dst at the given @offset.
 132 *
 133 * @dst:	destination leaf for the items
 134 * @src:	source leaf for the items
 135 * @dst_item:	the item nr we're copying into
 136 * @src_item:	the item nr we're copying from
 137 * @nr_items:	the number of items to copy
 138 *
 139 * Wrapper around copy_extent_buffer() that does the math to get the
 140 * appropriate offsets into the leaf from the item numbers.
 
 
 141 */
 142static inline void copy_leaf_items(const struct extent_buffer *dst,
 143				   const struct extent_buffer *src,
 144				   int dst_item, int src_item, int nr_items)
 145{
 146	copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, dst_item),
 147			      btrfs_item_nr_offset(src, src_item),
 148			      nr_items * sizeof(struct btrfs_item));
 149}
 150
 151/* This exists for btrfs-progs usages. */
 152u16 btrfs_csum_type_size(u16 type)
 153{
 154	return btrfs_csums[type].size;
 155}
 156
 157int btrfs_super_csum_size(const struct btrfs_super_block *s)
 158{
 159	u16 t = btrfs_super_csum_type(s);
 160	/*
 161	 * csum type is validated at mount time
 162	 */
 163	return btrfs_csum_type_size(t);
 164}
 165
 166const char *btrfs_super_csum_name(u16 csum_type)
 167{
 168	/* csum type is validated at mount time */
 169	return btrfs_csums[csum_type].name;
 170}
 171
 172/*
 173 * Return driver name if defined, otherwise the name that's also a valid driver
 174 * name
 175 */
 176const char *btrfs_super_csum_driver(u16 csum_type)
 177{
 178	/* csum type is validated at mount time */
 179	return btrfs_csums[csum_type].driver[0] ?
 180		btrfs_csums[csum_type].driver :
 181		btrfs_csums[csum_type].name;
 182}
 183
 184size_t __attribute_const__ btrfs_get_num_csums(void)
 185{
 186	return ARRAY_SIZE(btrfs_csums);
 187}
 188
 189struct btrfs_path *btrfs_alloc_path(void)
 190{
 191	might_sleep();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 192
 193	return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
 
 194}
 195
 196/* this also releases the path */
 197void btrfs_free_path(struct btrfs_path *p)
 198{
 199	if (!p)
 200		return;
 201	btrfs_release_path(p);
 202	kmem_cache_free(btrfs_path_cachep, p);
 203}
 204
 205/*
 206 * path release drops references on the extent buffers in the path
 207 * and it drops any locks held by this path
 208 *
 209 * It is safe to call this on paths that no locks or extent buffers held.
 210 */
 211noinline void btrfs_release_path(struct btrfs_path *p)
 212{
 213	int i;
 214
 215	for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
 216		p->slots[i] = 0;
 217		if (!p->nodes[i])
 218			continue;
 219		if (p->locks[i]) {
 220			btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
 221			p->locks[i] = 0;
 222		}
 223		free_extent_buffer(p->nodes[i]);
 224		p->nodes[i] = NULL;
 225	}
 226}
 227
 228/*
 229 * We want the transaction abort to print stack trace only for errors where the
 230 * cause could be a bug, eg. due to ENOSPC, and not for common errors that are
 231 * caused by external factors.
 232 */
 233bool __cold abort_should_print_stack(int error)
 234{
 235	switch (error) {
 236	case -EIO:
 237	case -EROFS:
 238	case -ENOMEM:
 239		return false;
 240	}
 241	return true;
 242}
 243
 244/*
 245 * safely gets a reference on the root node of a tree.  A lock
 246 * is not taken, so a concurrent writer may put a different node
 247 * at the root of the tree.  See btrfs_lock_root_node for the
 248 * looping required.
 249 *
 250 * The extent buffer returned by this has a reference taken, so
 251 * it won't disappear.  It may stop being the root of the tree
 252 * at any time because there are no locks held.
 253 */
 254struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
 255{
 256	struct extent_buffer *eb;
 257
 258	while (1) {
 259		rcu_read_lock();
 260		eb = rcu_dereference(root->node);
 261
 262		/*
 263		 * RCU really hurts here, we could free up the root node because
 264		 * it was COWed but we may not get the new root node yet so do
 265		 * the inc_not_zero dance and if it doesn't work then
 266		 * synchronize_rcu and try again.
 267		 */
 268		if (atomic_inc_not_zero(&eb->refs)) {
 269			rcu_read_unlock();
 270			break;
 271		}
 272		rcu_read_unlock();
 273		synchronize_rcu();
 274	}
 275	return eb;
 276}
 277
 278/*
 279 * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
 280 * just get put onto a simple dirty list.  Transaction walks this list to make
 281 * sure they get properly updated on disk.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 282 */
 283static void add_root_to_dirty_list(struct btrfs_root *root)
 284{
 285	struct btrfs_fs_info *fs_info = root->fs_info;
 286
 287	if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
 288	    !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
 289		return;
 290
 291	spin_lock(&fs_info->trans_lock);
 292	if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
 293		/* Want the extent tree to be the last on the list */
 294		if (btrfs_root_id(root) == BTRFS_EXTENT_TREE_OBJECTID)
 295			list_move_tail(&root->dirty_list,
 296				       &fs_info->dirty_cowonly_roots);
 297		else
 298			list_move(&root->dirty_list,
 299				  &fs_info->dirty_cowonly_roots);
 300	}
 301	spin_unlock(&fs_info->trans_lock);
 302}
 303
 304/*
 305 * used by snapshot creation to make a copy of a root for a tree with
 306 * a given objectid.  The buffer with the new root node is returned in
 307 * cow_ret, and this func returns zero on success or a negative error code.
 308 */
 309int btrfs_copy_root(struct btrfs_trans_handle *trans,
 310		      struct btrfs_root *root,
 311		      struct extent_buffer *buf,
 312		      struct extent_buffer **cow_ret, u64 new_root_objectid)
 313{
 314	struct btrfs_fs_info *fs_info = root->fs_info;
 315	struct extent_buffer *cow;
 316	int ret = 0;
 317	int level;
 318	struct btrfs_disk_key disk_key;
 319	u64 reloc_src_root = 0;
 320
 321	WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 322		trans->transid != fs_info->running_transaction->transid);
 323	WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 324		trans->transid != btrfs_get_root_last_trans(root));
 325
 326	level = btrfs_header_level(buf);
 327	if (level == 0)
 328		btrfs_item_key(buf, &disk_key, 0);
 329	else
 330		btrfs_node_key(buf, &disk_key, 0);
 331
 332	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 333		reloc_src_root = btrfs_header_owner(buf);
 334	cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
 335				     &disk_key, level, buf->start, 0,
 336				     reloc_src_root, BTRFS_NESTING_NEW_ROOT);
 337	if (IS_ERR(cow))
 338		return PTR_ERR(cow);
 339
 340	copy_extent_buffer_full(cow, buf);
 341	btrfs_set_header_bytenr(cow, cow->start);
 342	btrfs_set_header_generation(cow, trans->transid);
 343	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 344	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 345				     BTRFS_HEADER_FLAG_RELOC);
 346	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 347		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 348	else
 349		btrfs_set_header_owner(cow, new_root_objectid);
 350
 351	write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
 352
 353	WARN_ON(btrfs_header_generation(buf) > trans->transid);
 354	if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 355		ret = btrfs_inc_ref(trans, root, cow, 1);
 356	else
 357		ret = btrfs_inc_ref(trans, root, cow, 0);
 358	if (ret) {
 359		btrfs_tree_unlock(cow);
 360		free_extent_buffer(cow);
 361		btrfs_abort_transaction(trans, ret);
 362		return ret;
 363	}
 364
 365	btrfs_mark_buffer_dirty(trans, cow);
 366	*cow_ret = cow;
 367	return 0;
 368}
 369
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 370/*
 371 * check if the tree block can be shared by multiple trees
 
 
 
 
 
 372 */
 373bool btrfs_block_can_be_shared(struct btrfs_trans_handle *trans,
 374			       struct btrfs_root *root,
 375			       struct extent_buffer *buf)
 376{
 377	const u64 buf_gen = btrfs_header_generation(buf);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 378
 379	/*
 380	 * Tree blocks not in shareable trees and tree roots are never shared.
 381	 * If a block was allocated after the last snapshot and the block was
 382	 * not allocated by tree relocation, we know the block is not shared.
 383	 */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 384
 385	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
 386		return false;
 
 
 
 387
 388	if (buf == root->node)
 389		return false;
 390
 391	if (buf_gen > btrfs_root_last_snapshot(&root->root_item) &&
 392	    !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))
 393		return false;
 394
 395	if (buf != root->commit_root)
 396		return true;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 397
 398	/*
 399	 * An extent buffer that used to be the commit root may still be shared
 400	 * because the tree height may have increased and it became a child of a
 401	 * higher level root. This can happen when snapshotting a subvolume
 402	 * created in the current transaction.
 403	 */
 404	if (buf_gen == trans->transid)
 405		return true;
 
 
 
 406
 407	return false;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 408}
 409
 410static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 411				       struct btrfs_root *root,
 412				       struct extent_buffer *buf,
 413				       struct extent_buffer *cow,
 414				       int *last_ref)
 415{
 416	struct btrfs_fs_info *fs_info = root->fs_info;
 417	u64 refs;
 418	u64 owner;
 419	u64 flags;
 
 420	int ret;
 421
 422	/*
 423	 * Backrefs update rules:
 424	 *
 425	 * Always use full backrefs for extent pointers in tree block
 426	 * allocated by tree relocation.
 427	 *
 428	 * If a shared tree block is no longer referenced by its owner
 429	 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 430	 * use full backrefs for extent pointers in tree block.
 431	 *
 432	 * If a tree block is been relocating
 433	 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
 434	 * use full backrefs for extent pointers in tree block.
 435	 * The reason for this is some operations (such as drop tree)
 436	 * are only allowed for blocks use full backrefs.
 437	 */
 438
 439	if (btrfs_block_can_be_shared(trans, root, buf)) {
 440		ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
 441					       btrfs_header_level(buf), 1,
 442					       &refs, &flags, NULL);
 443		if (ret)
 444			return ret;
 445		if (unlikely(refs == 0)) {
 446			btrfs_crit(fs_info,
 447		"found 0 references for tree block at bytenr %llu level %d root %llu",
 448				   buf->start, btrfs_header_level(buf),
 449				   btrfs_root_id(root));
 450			ret = -EUCLEAN;
 451			btrfs_abort_transaction(trans, ret);
 452			return ret;
 453		}
 454	} else {
 455		refs = 1;
 456		if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID ||
 457		    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 458			flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
 459		else
 460			flags = 0;
 461	}
 462
 463	owner = btrfs_header_owner(buf);
 464	if (unlikely(owner == BTRFS_TREE_RELOC_OBJECTID &&
 465		     !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))) {
 466		btrfs_crit(fs_info,
 467"found tree block at bytenr %llu level %d root %llu refs %llu flags %llx without full backref flag set",
 468			   buf->start, btrfs_header_level(buf),
 469			   btrfs_root_id(root), refs, flags);
 470		ret = -EUCLEAN;
 471		btrfs_abort_transaction(trans, ret);
 472		return ret;
 473	}
 474
 475	if (refs > 1) {
 476		if ((owner == btrfs_root_id(root) ||
 477		     btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) &&
 478		    !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 479			ret = btrfs_inc_ref(trans, root, buf, 1);
 480			if (ret)
 481				return ret;
 482
 483			if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) {
 
 484				ret = btrfs_dec_ref(trans, root, buf, 0);
 485				if (ret)
 486					return ret;
 487				ret = btrfs_inc_ref(trans, root, cow, 1);
 488				if (ret)
 489					return ret;
 490			}
 491			ret = btrfs_set_disk_extent_flags(trans, buf,
 492						  BTRFS_BLOCK_FLAG_FULL_BACKREF);
 493			if (ret)
 494				return ret;
 495		} else {
 496
 497			if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
 
 498				ret = btrfs_inc_ref(trans, root, cow, 1);
 499			else
 500				ret = btrfs_inc_ref(trans, root, cow, 0);
 501			if (ret)
 502				return ret;
 503		}
 
 
 
 
 
 
 
 
 
 
 504	} else {
 505		if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
 506			if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
 
 507				ret = btrfs_inc_ref(trans, root, cow, 1);
 508			else
 509				ret = btrfs_inc_ref(trans, root, cow, 0);
 510			if (ret)
 511				return ret;
 512			ret = btrfs_dec_ref(trans, root, buf, 1);
 513			if (ret)
 514				return ret;
 515		}
 516		btrfs_clear_buffer_dirty(trans, buf);
 517		*last_ref = 1;
 518	}
 519	return 0;
 520}
 521
 522/*
 523 * does the dirty work in cow of a single block.  The parent block (if
 524 * supplied) is updated to point to the new cow copy.  The new buffer is marked
 525 * dirty and returned locked.  If you modify the block it needs to be marked
 526 * dirty again.
 527 *
 528 * search_start -- an allocation hint for the new block
 529 *
 530 * empty_size -- a hint that you plan on doing more cow.  This is the size in
 531 * bytes the allocator should try to find free next to the block it returns.
 532 * This is just a hint and may be ignored by the allocator.
 533 */
 534int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
 535			  struct btrfs_root *root,
 536			  struct extent_buffer *buf,
 537			  struct extent_buffer *parent, int parent_slot,
 538			  struct extent_buffer **cow_ret,
 539			  u64 search_start, u64 empty_size,
 540			  enum btrfs_lock_nesting nest)
 541{
 542	struct btrfs_fs_info *fs_info = root->fs_info;
 543	struct btrfs_disk_key disk_key;
 544	struct extent_buffer *cow;
 545	int level, ret;
 546	int last_ref = 0;
 547	int unlock_orig = 0;
 548	u64 parent_start = 0;
 549	u64 reloc_src_root = 0;
 550
 551	if (*cow_ret == buf)
 552		unlock_orig = 1;
 553
 554	btrfs_assert_tree_write_locked(buf);
 555
 556	WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 557		trans->transid != fs_info->running_transaction->transid);
 558	WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 559		trans->transid != btrfs_get_root_last_trans(root));
 560
 561	level = btrfs_header_level(buf);
 562
 563	if (level == 0)
 564		btrfs_item_key(buf, &disk_key, 0);
 565	else
 566		btrfs_node_key(buf, &disk_key, 0);
 567
 568	if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) {
 569		if (parent)
 570			parent_start = parent->start;
 571		reloc_src_root = btrfs_header_owner(buf);
 572	}
 573	cow = btrfs_alloc_tree_block(trans, root, parent_start,
 574				     btrfs_root_id(root), &disk_key, level,
 575				     search_start, empty_size, reloc_src_root, nest);
 576	if (IS_ERR(cow))
 577		return PTR_ERR(cow);
 578
 579	/* cow is set to blocking by btrfs_init_new_buffer */
 580
 581	copy_extent_buffer_full(cow, buf);
 582	btrfs_set_header_bytenr(cow, cow->start);
 583	btrfs_set_header_generation(cow, trans->transid);
 584	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 585	btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 586				     BTRFS_HEADER_FLAG_RELOC);
 587	if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
 588		btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 589	else
 590		btrfs_set_header_owner(cow, btrfs_root_id(root));
 591
 592	write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
 593
 594	ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
 595	if (ret) {
 596		btrfs_abort_transaction(trans, ret);
 597		goto error_unlock_cow;
 598	}
 599
 600	if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
 601		ret = btrfs_reloc_cow_block(trans, root, buf, cow);
 602		if (ret) {
 603			btrfs_abort_transaction(trans, ret);
 604			goto error_unlock_cow;
 605		}
 606	}
 607
 608	if (buf == root->node) {
 609		WARN_ON(parent && parent != buf);
 610		if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID ||
 611		    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 612			parent_start = buf->start;
 613
 614		ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
 615		if (ret < 0) {
 616			btrfs_abort_transaction(trans, ret);
 617			goto error_unlock_cow;
 618		}
 619		atomic_inc(&cow->refs);
 620		rcu_assign_pointer(root->node, cow);
 621
 622		ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
 623					    parent_start, last_ref);
 624		free_extent_buffer(buf);
 625		add_root_to_dirty_list(root);
 626		if (ret < 0) {
 627			btrfs_abort_transaction(trans, ret);
 628			goto error_unlock_cow;
 629		}
 630	} else {
 631		WARN_ON(trans->transid != btrfs_header_generation(parent));
 632		ret = btrfs_tree_mod_log_insert_key(parent, parent_slot,
 633						    BTRFS_MOD_LOG_KEY_REPLACE);
 634		if (ret) {
 635			btrfs_abort_transaction(trans, ret);
 636			goto error_unlock_cow;
 637		}
 638		btrfs_set_node_blockptr(parent, parent_slot,
 639					cow->start);
 640		btrfs_set_node_ptr_generation(parent, parent_slot,
 641					      trans->transid);
 642		btrfs_mark_buffer_dirty(trans, parent);
 643		if (last_ref) {
 644			ret = btrfs_tree_mod_log_free_eb(buf);
 645			if (ret) {
 646				btrfs_abort_transaction(trans, ret);
 647				goto error_unlock_cow;
 648			}
 649		}
 650		ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
 651					    parent_start, last_ref);
 652		if (ret < 0) {
 653			btrfs_abort_transaction(trans, ret);
 654			goto error_unlock_cow;
 655		}
 656	}
 657
 658	trace_btrfs_cow_block(root, buf, cow);
 659	if (unlock_orig)
 660		btrfs_tree_unlock(buf);
 661	free_extent_buffer_stale(buf);
 662	btrfs_mark_buffer_dirty(trans, cow);
 663	*cow_ret = cow;
 664	return 0;
 
 665
 666error_unlock_cow:
 667	btrfs_tree_unlock(cow);
 668	free_extent_buffer(cow);
 669	return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 670}
 671
 672static inline int should_cow_block(struct btrfs_trans_handle *trans,
 673				   struct btrfs_root *root,
 674				   struct extent_buffer *buf)
 675{
 676	if (btrfs_is_testing(root->fs_info))
 677		return 0;
 678
 679	/* Ensure we can see the FORCE_COW bit */
 680	smp_mb__before_atomic();
 681
 682	/*
 683	 * We do not need to cow a block if
 684	 * 1) this block is not created or changed in this transaction;
 685	 * 2) this block does not belong to TREE_RELOC tree;
 686	 * 3) the root is not forced COW.
 687	 *
 688	 * What is forced COW:
 689	 *    when we create snapshot during committing the transaction,
 690	 *    after we've finished copying src root, we must COW the shared
 691	 *    block to ensure the metadata consistency.
 692	 */
 693	if (btrfs_header_generation(buf) == trans->transid &&
 694	    !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
 695	    !(btrfs_root_id(root) != BTRFS_TREE_RELOC_OBJECTID &&
 696	      btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
 697	    !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
 698		return 0;
 699	return 1;
 700}
 701
 702/*
 703 * COWs a single block, see btrfs_force_cow_block() for the real work.
 704 * This version of it has extra checks so that a block isn't COWed more than
 705 * once per transaction, as long as it hasn't been written yet
 706 */
 707int btrfs_cow_block(struct btrfs_trans_handle *trans,
 708		    struct btrfs_root *root, struct extent_buffer *buf,
 709		    struct extent_buffer *parent, int parent_slot,
 710		    struct extent_buffer **cow_ret,
 711		    enum btrfs_lock_nesting nest)
 712{
 713	struct btrfs_fs_info *fs_info = root->fs_info;
 714	u64 search_start;
 
 715
 716	if (unlikely(test_bit(BTRFS_ROOT_DELETING, &root->state))) {
 717		btrfs_abort_transaction(trans, -EUCLEAN);
 718		btrfs_crit(fs_info,
 719		   "attempt to COW block %llu on root %llu that is being deleted",
 720			   buf->start, btrfs_root_id(root));
 721		return -EUCLEAN;
 722	}
 723
 724	/*
 725	 * COWing must happen through a running transaction, which always
 726	 * matches the current fs generation (it's a transaction with a state
 727	 * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
 728	 * into error state to prevent the commit of any transaction.
 729	 */
 730	if (unlikely(trans->transaction != fs_info->running_transaction ||
 731		     trans->transid != fs_info->generation)) {
 732		btrfs_abort_transaction(trans, -EUCLEAN);
 733		btrfs_crit(fs_info,
 734"unexpected transaction when attempting to COW block %llu on root %llu, transaction %llu running transaction %llu fs generation %llu",
 735			   buf->start, btrfs_root_id(root), trans->transid,
 736			   fs_info->running_transaction->transid,
 737			   fs_info->generation);
 738		return -EUCLEAN;
 739	}
 740
 741	if (!should_cow_block(trans, root, buf)) {
 
 742		*cow_ret = buf;
 743		return 0;
 744	}
 745
 746	search_start = round_down(buf->start, SZ_1G);
 747
 748	/*
 749	 * Before CoWing this block for later modification, check if it's
 750	 * the subtree root and do the delayed subtree trace if needed.
 751	 *
 752	 * Also We don't care about the error, as it's handled internally.
 753	 */
 754	btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
 755	return btrfs_force_cow_block(trans, root, buf, parent, parent_slot,
 756				     cow_ret, search_start, 0, nest);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 757}
 758ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
 759
 760/*
 761 * same as comp_keys only with two btrfs_key's
 762 */
 763int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
 764{
 765	if (k1->objectid > k2->objectid)
 766		return 1;
 767	if (k1->objectid < k2->objectid)
 768		return -1;
 769	if (k1->type > k2->type)
 770		return 1;
 771	if (k1->type < k2->type)
 772		return -1;
 773	if (k1->offset > k2->offset)
 774		return 1;
 775	if (k1->offset < k2->offset)
 776		return -1;
 777	return 0;
 778}
 779
 780/*
 781 * Search for a key in the given extent_buffer.
 782 *
 783 * The lower boundary for the search is specified by the slot number @first_slot.
 784 * Use a value of 0 to search over the whole extent buffer. Works for both
 785 * leaves and nodes.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 786 *
 787 * The slot in the extent buffer is returned via @slot. If the key exists in the
 788 * extent buffer, then @slot will point to the slot where the key is, otherwise
 789 * it points to the slot where you would insert the key.
 790 *
 791 * Slot may point to the total number of items (i.e. one position beyond the last
 792 * key) if the key is bigger than the last key in the extent buffer.
 793 */
 794int btrfs_bin_search(struct extent_buffer *eb, int first_slot,
 795		     const struct btrfs_key *key, int *slot)
 
 
 796{
 797	unsigned long p;
 798	int item_size;
 799	/*
 800	 * Use unsigned types for the low and high slots, so that we get a more
 801	 * efficient division in the search loop below.
 802	 */
 803	u32 low = first_slot;
 804	u32 high = btrfs_header_nritems(eb);
 805	int ret;
 806	const int key_size = sizeof(struct btrfs_disk_key);
 
 
 
 
 
 
 807
 808	if (unlikely(low > high)) {
 809		btrfs_err(eb->fs_info,
 810		 "%s: low (%u) > high (%u) eb %llu owner %llu level %d",
 811			  __func__, low, high, eb->start,
 812			  btrfs_header_owner(eb), btrfs_header_level(eb));
 813		return -EINVAL;
 814	}
 815
 816	if (btrfs_header_level(eb) == 0) {
 817		p = offsetof(struct btrfs_leaf, items);
 818		item_size = sizeof(struct btrfs_item);
 819	} else {
 820		p = offsetof(struct btrfs_node, ptrs);
 821		item_size = sizeof(struct btrfs_key_ptr);
 822	}
 823
 824	while (low < high) {
 825		const int unit_size = eb->folio_size;
 826		unsigned long oil;
 827		unsigned long offset;
 828		struct btrfs_disk_key *tmp;
 829		struct btrfs_disk_key unaligned;
 830		int mid;
 831
 832		mid = (low + high) / 2;
 833		offset = p + mid * item_size;
 834		oil = get_eb_offset_in_folio(eb, offset);
 835
 836		if (oil + key_size <= unit_size) {
 837			const unsigned long idx = get_eb_folio_index(eb, offset);
 838			char *kaddr = folio_address(eb->folios[idx]);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 839
 840			oil = get_eb_offset_in_folio(eb, offset);
 841			tmp = (struct btrfs_disk_key *)(kaddr + oil);
 842		} else {
 843			read_extent_buffer(eb, &unaligned, offset, key_size);
 844			tmp = &unaligned;
 845		}
 846
 847		ret = btrfs_comp_keys(tmp, key);
 848
 849		if (ret < 0)
 850			low = mid + 1;
 851		else if (ret > 0)
 852			high = mid;
 853		else {
 854			*slot = mid;
 855			return 0;
 856		}
 857	}
 858	*slot = low;
 859	return 1;
 860}
 861
 862static void root_add_used_bytes(struct btrfs_root *root)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 863{
 864	spin_lock(&root->accounting_lock);
 865	btrfs_set_root_used(&root->root_item,
 866		btrfs_root_used(&root->root_item) + root->fs_info->nodesize);
 867	spin_unlock(&root->accounting_lock);
 868}
 869
 870static void root_sub_used_bytes(struct btrfs_root *root)
 871{
 872	spin_lock(&root->accounting_lock);
 873	btrfs_set_root_used(&root->root_item,
 874		btrfs_root_used(&root->root_item) - root->fs_info->nodesize);
 875	spin_unlock(&root->accounting_lock);
 876}
 877
 878/* given a node and slot number, this reads the blocks it points to.  The
 879 * extent buffer is returned with a reference taken (but unlocked).
 880 */
 881struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
 882					   int slot)
 
 883{
 884	int level = btrfs_header_level(parent);
 885	struct btrfs_tree_parent_check check = { 0 };
 886	struct extent_buffer *eb;
 
 887
 888	if (slot < 0 || slot >= btrfs_header_nritems(parent))
 889		return ERR_PTR(-ENOENT);
 890
 891	ASSERT(level);
 892
 893	check.level = level - 1;
 894	check.transid = btrfs_node_ptr_generation(parent, slot);
 895	check.owner_root = btrfs_header_owner(parent);
 896	check.has_first_key = true;
 897	btrfs_node_key_to_cpu(parent, &check.first_key, slot);
 898
 899	eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
 900			     &check);
 901	if (IS_ERR(eb))
 902		return eb;
 903	if (!extent_buffer_uptodate(eb)) {
 904		free_extent_buffer(eb);
 905		return ERR_PTR(-EIO);
 906	}
 907
 908	return eb;
 909}
 910
 911/*
 912 * node level balancing, used to make sure nodes are in proper order for
 913 * item deletion.  We balance from the top down, so we have to make sure
 914 * that a deletion won't leave an node completely empty later on.
 915 */
 916static noinline int balance_level(struct btrfs_trans_handle *trans,
 917			 struct btrfs_root *root,
 918			 struct btrfs_path *path, int level)
 919{
 920	struct btrfs_fs_info *fs_info = root->fs_info;
 921	struct extent_buffer *right = NULL;
 922	struct extent_buffer *mid;
 923	struct extent_buffer *left = NULL;
 924	struct extent_buffer *parent = NULL;
 925	int ret = 0;
 926	int wret;
 927	int pslot;
 928	int orig_slot = path->slots[level];
 929	u64 orig_ptr;
 930
 931	ASSERT(level > 0);
 
 932
 933	mid = path->nodes[level];
 934
 935	WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
 
 936	WARN_ON(btrfs_header_generation(mid) != trans->transid);
 937
 938	orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 939
 940	if (level < BTRFS_MAX_LEVEL - 1) {
 941		parent = path->nodes[level + 1];
 942		pslot = path->slots[level + 1];
 943	}
 944
 945	/*
 946	 * deal with the case where there is only one pointer in the root
 947	 * by promoting the node below to a root
 948	 */
 949	if (!parent) {
 950		struct extent_buffer *child;
 951
 952		if (btrfs_header_nritems(mid) != 1)
 953			return 0;
 954
 955		/* promote the child to a root */
 956		child = btrfs_read_node_slot(mid, 0);
 957		if (IS_ERR(child)) {
 958			ret = PTR_ERR(child);
 959			goto out;
 
 960		}
 961
 962		btrfs_tree_lock(child);
 963		ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
 964				      BTRFS_NESTING_COW);
 965		if (ret) {
 966			btrfs_tree_unlock(child);
 967			free_extent_buffer(child);
 968			goto out;
 969		}
 970
 971		ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
 972		if (ret < 0) {
 973			btrfs_tree_unlock(child);
 974			free_extent_buffer(child);
 975			btrfs_abort_transaction(trans, ret);
 976			goto out;
 977		}
 978		rcu_assign_pointer(root->node, child);
 979
 980		add_root_to_dirty_list(root);
 981		btrfs_tree_unlock(child);
 982
 983		path->locks[level] = 0;
 984		path->nodes[level] = NULL;
 985		btrfs_clear_buffer_dirty(trans, mid);
 986		btrfs_tree_unlock(mid);
 987		/* once for the path */
 988		free_extent_buffer(mid);
 989
 990		root_sub_used_bytes(root);
 991		ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
 992		/* once for the root ptr */
 993		free_extent_buffer_stale(mid);
 994		if (ret < 0) {
 995			btrfs_abort_transaction(trans, ret);
 996			goto out;
 997		}
 998		return 0;
 999	}
1000	if (btrfs_header_nritems(mid) >
1001	    BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1002		return 0;
1003
1004	if (pslot) {
1005		left = btrfs_read_node_slot(parent, pslot - 1);
1006		if (IS_ERR(left)) {
1007			ret = PTR_ERR(left);
1008			left = NULL;
1009			goto out;
1010		}
1011
1012		btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
 
 
1013		wret = btrfs_cow_block(trans, root, left,
1014				       parent, pslot - 1, &left,
1015				       BTRFS_NESTING_LEFT_COW);
1016		if (wret) {
1017			ret = wret;
1018			goto out;
1019		}
1020	}
1021
1022	if (pslot + 1 < btrfs_header_nritems(parent)) {
1023		right = btrfs_read_node_slot(parent, pslot + 1);
1024		if (IS_ERR(right)) {
1025			ret = PTR_ERR(right);
1026			right = NULL;
1027			goto out;
1028		}
1029
1030		btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
 
 
1031		wret = btrfs_cow_block(trans, root, right,
1032				       parent, pslot + 1, &right,
1033				       BTRFS_NESTING_RIGHT_COW);
1034		if (wret) {
1035			ret = wret;
1036			goto out;
1037		}
1038	}
1039
1040	/* first, try to make some room in the middle buffer */
1041	if (left) {
1042		orig_slot += btrfs_header_nritems(left);
1043		wret = push_node_left(trans, left, mid, 1);
1044		if (wret < 0)
1045			ret = wret;
1046	}
1047
1048	/*
1049	 * then try to empty the right most buffer into the middle
1050	 */
1051	if (right) {
1052		wret = push_node_left(trans, mid, right, 1);
1053		if (wret < 0 && wret != -ENOSPC)
1054			ret = wret;
1055		if (btrfs_header_nritems(right) == 0) {
1056			btrfs_clear_buffer_dirty(trans, right);
1057			btrfs_tree_unlock(right);
1058			ret = btrfs_del_ptr(trans, root, path, level + 1, pslot + 1);
1059			if (ret < 0) {
1060				free_extent_buffer_stale(right);
1061				right = NULL;
1062				goto out;
1063			}
1064			root_sub_used_bytes(root);
1065			ret = btrfs_free_tree_block(trans, btrfs_root_id(root),
1066						    right, 0, 1);
1067			free_extent_buffer_stale(right);
1068			right = NULL;
1069			if (ret < 0) {
1070				btrfs_abort_transaction(trans, ret);
1071				goto out;
1072			}
1073		} else {
1074			struct btrfs_disk_key right_key;
1075			btrfs_node_key(right, &right_key, 0);
1076			ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1077					BTRFS_MOD_LOG_KEY_REPLACE);
1078			if (ret < 0) {
1079				btrfs_abort_transaction(trans, ret);
1080				goto out;
1081			}
1082			btrfs_set_node_key(parent, &right_key, pslot + 1);
1083			btrfs_mark_buffer_dirty(trans, parent);
1084		}
1085	}
1086	if (btrfs_header_nritems(mid) == 1) {
1087		/*
1088		 * we're not allowed to leave a node with one item in the
1089		 * tree during a delete.  A deletion from lower in the tree
1090		 * could try to delete the only pointer in this node.
1091		 * So, pull some keys from the left.
1092		 * There has to be a left pointer at this point because
1093		 * otherwise we would have pulled some pointers from the
1094		 * right
1095		 */
1096		if (unlikely(!left)) {
1097			btrfs_crit(fs_info,
1098"missing left child when middle child only has 1 item, parent bytenr %llu level %d mid bytenr %llu root %llu",
1099				   parent->start, btrfs_header_level(parent),
1100				   mid->start, btrfs_root_id(root));
1101			ret = -EUCLEAN;
1102			btrfs_abort_transaction(trans, ret);
1103			goto out;
1104		}
1105		wret = balance_node_right(trans, mid, left);
1106		if (wret < 0) {
1107			ret = wret;
1108			goto out;
1109		}
1110		if (wret == 1) {
1111			wret = push_node_left(trans, left, mid, 1);
1112			if (wret < 0)
1113				ret = wret;
1114		}
1115		BUG_ON(wret == 1);
1116	}
1117	if (btrfs_header_nritems(mid) == 0) {
1118		btrfs_clear_buffer_dirty(trans, mid);
1119		btrfs_tree_unlock(mid);
1120		ret = btrfs_del_ptr(trans, root, path, level + 1, pslot);
1121		if (ret < 0) {
1122			free_extent_buffer_stale(mid);
1123			mid = NULL;
1124			goto out;
1125		}
1126		root_sub_used_bytes(root);
1127		ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
1128		free_extent_buffer_stale(mid);
1129		mid = NULL;
1130		if (ret < 0) {
1131			btrfs_abort_transaction(trans, ret);
1132			goto out;
1133		}
1134	} else {
1135		/* update the parent key to reflect our changes */
1136		struct btrfs_disk_key mid_key;
1137		btrfs_node_key(mid, &mid_key, 0);
1138		ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1139						    BTRFS_MOD_LOG_KEY_REPLACE);
1140		if (ret < 0) {
1141			btrfs_abort_transaction(trans, ret);
1142			goto out;
1143		}
1144		btrfs_set_node_key(parent, &mid_key, pslot);
1145		btrfs_mark_buffer_dirty(trans, parent);
1146	}
1147
1148	/* update the path */
1149	if (left) {
1150		if (btrfs_header_nritems(left) > orig_slot) {
1151			atomic_inc(&left->refs);
1152			/* left was locked after cow */
1153			path->nodes[level] = left;
1154			path->slots[level + 1] -= 1;
1155			path->slots[level] = orig_slot;
1156			if (mid) {
1157				btrfs_tree_unlock(mid);
1158				free_extent_buffer(mid);
1159			}
1160		} else {
1161			orig_slot -= btrfs_header_nritems(left);
1162			path->slots[level] = orig_slot;
1163		}
1164	}
1165	/* double check we haven't messed things up */
1166	if (orig_ptr !=
1167	    btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1168		BUG();
1169out:
1170	if (right) {
1171		btrfs_tree_unlock(right);
1172		free_extent_buffer(right);
1173	}
1174	if (left) {
1175		if (path->nodes[level] != left)
1176			btrfs_tree_unlock(left);
1177		free_extent_buffer(left);
1178	}
1179	return ret;
1180}
1181
1182/* Node balancing for insertion.  Here we only split or push nodes around
1183 * when they are completely full.  This is also done top down, so we
1184 * have to be pessimistic.
1185 */
1186static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1187					  struct btrfs_root *root,
1188					  struct btrfs_path *path, int level)
1189{
1190	struct btrfs_fs_info *fs_info = root->fs_info;
1191	struct extent_buffer *right = NULL;
1192	struct extent_buffer *mid;
1193	struct extent_buffer *left = NULL;
1194	struct extent_buffer *parent = NULL;
1195	int ret = 0;
1196	int wret;
1197	int pslot;
1198	int orig_slot = path->slots[level];
1199
1200	if (level == 0)
1201		return 1;
1202
1203	mid = path->nodes[level];
1204	WARN_ON(btrfs_header_generation(mid) != trans->transid);
1205
1206	if (level < BTRFS_MAX_LEVEL - 1) {
1207		parent = path->nodes[level + 1];
1208		pslot = path->slots[level + 1];
1209	}
1210
1211	if (!parent)
1212		return 1;
1213
 
 
 
 
1214	/* first, try to make some room in the middle buffer */
1215	if (pslot) {
1216		u32 left_nr;
1217
1218		left = btrfs_read_node_slot(parent, pslot - 1);
1219		if (IS_ERR(left))
1220			return PTR_ERR(left);
1221
1222		btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
1223
1224		left_nr = btrfs_header_nritems(left);
1225		if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1226			wret = 1;
1227		} else {
1228			ret = btrfs_cow_block(trans, root, left, parent,
1229					      pslot - 1, &left,
1230					      BTRFS_NESTING_LEFT_COW);
1231			if (ret)
1232				wret = 1;
1233			else {
1234				wret = push_node_left(trans, left, mid, 0);
 
1235			}
1236		}
1237		if (wret < 0)
1238			ret = wret;
1239		if (wret == 0) {
1240			struct btrfs_disk_key disk_key;
1241			orig_slot += left_nr;
1242			btrfs_node_key(mid, &disk_key, 0);
1243			ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1244					BTRFS_MOD_LOG_KEY_REPLACE);
1245			if (ret < 0) {
1246				btrfs_tree_unlock(left);
1247				free_extent_buffer(left);
1248				btrfs_abort_transaction(trans, ret);
1249				return ret;
1250			}
1251			btrfs_set_node_key(parent, &disk_key, pslot);
1252			btrfs_mark_buffer_dirty(trans, parent);
1253			if (btrfs_header_nritems(left) > orig_slot) {
1254				path->nodes[level] = left;
1255				path->slots[level + 1] -= 1;
1256				path->slots[level] = orig_slot;
1257				btrfs_tree_unlock(mid);
1258				free_extent_buffer(mid);
1259			} else {
1260				orig_slot -=
1261					btrfs_header_nritems(left);
1262				path->slots[level] = orig_slot;
1263				btrfs_tree_unlock(left);
1264				free_extent_buffer(left);
1265			}
1266			return 0;
1267		}
1268		btrfs_tree_unlock(left);
1269		free_extent_buffer(left);
1270	}
 
 
 
1271
1272	/*
1273	 * then try to empty the right most buffer into the middle
1274	 */
1275	if (pslot + 1 < btrfs_header_nritems(parent)) {
1276		u32 right_nr;
1277
1278		right = btrfs_read_node_slot(parent, pslot + 1);
1279		if (IS_ERR(right))
1280			return PTR_ERR(right);
1281
1282		btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
1283
1284		right_nr = btrfs_header_nritems(right);
1285		if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1286			wret = 1;
1287		} else {
1288			ret = btrfs_cow_block(trans, root, right,
1289					      parent, pslot + 1,
1290					      &right, BTRFS_NESTING_RIGHT_COW);
1291			if (ret)
1292				wret = 1;
1293			else {
1294				wret = balance_node_right(trans, right, mid);
 
1295			}
1296		}
1297		if (wret < 0)
1298			ret = wret;
1299		if (wret == 0) {
1300			struct btrfs_disk_key disk_key;
1301
1302			btrfs_node_key(right, &disk_key, 0);
1303			ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1304					BTRFS_MOD_LOG_KEY_REPLACE);
1305			if (ret < 0) {
1306				btrfs_tree_unlock(right);
1307				free_extent_buffer(right);
1308				btrfs_abort_transaction(trans, ret);
1309				return ret;
1310			}
1311			btrfs_set_node_key(parent, &disk_key, pslot + 1);
1312			btrfs_mark_buffer_dirty(trans, parent);
1313
1314			if (btrfs_header_nritems(mid) <= orig_slot) {
1315				path->nodes[level] = right;
1316				path->slots[level + 1] += 1;
1317				path->slots[level] = orig_slot -
1318					btrfs_header_nritems(mid);
1319				btrfs_tree_unlock(mid);
1320				free_extent_buffer(mid);
1321			} else {
1322				btrfs_tree_unlock(right);
1323				free_extent_buffer(right);
1324			}
1325			return 0;
1326		}
1327		btrfs_tree_unlock(right);
1328		free_extent_buffer(right);
1329	}
1330	return 1;
1331}
1332
1333/*
1334 * readahead one full node of leaves, finding things that are close
1335 * to the block in 'slot', and triggering ra on them.
1336 */
1337static void reada_for_search(struct btrfs_fs_info *fs_info,
1338			     struct btrfs_path *path,
1339			     int level, int slot, u64 objectid)
1340{
1341	struct extent_buffer *node;
1342	struct btrfs_disk_key disk_key;
1343	u32 nritems;
1344	u64 search;
1345	u64 target;
1346	u64 nread = 0;
1347	u64 nread_max;
1348	u32 nr;
1349	u32 blocksize;
1350	u32 nscan = 0;
1351
1352	if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
1353		return;
1354
1355	if (!path->nodes[level])
1356		return;
1357
1358	node = path->nodes[level];
1359
1360	/*
1361	 * Since the time between visiting leaves is much shorter than the time
1362	 * between visiting nodes, limit read ahead of nodes to 1, to avoid too
1363	 * much IO at once (possibly random).
1364	 */
1365	if (path->reada == READA_FORWARD_ALWAYS) {
1366		if (level > 1)
1367			nread_max = node->fs_info->nodesize;
1368		else
1369			nread_max = SZ_128K;
1370	} else {
1371		nread_max = SZ_64K;
1372	}
1373
1374	search = btrfs_node_blockptr(node, slot);
1375	blocksize = fs_info->nodesize;
1376	if (path->reada != READA_FORWARD_ALWAYS) {
1377		struct extent_buffer *eb;
1378
1379		eb = find_extent_buffer(fs_info, search);
1380		if (eb) {
1381			free_extent_buffer(eb);
1382			return;
1383		}
1384	}
1385
1386	target = search;
1387
1388	nritems = btrfs_header_nritems(node);
1389	nr = slot;
1390
1391	while (1) {
1392		if (path->reada == READA_BACK) {
1393			if (nr == 0)
1394				break;
1395			nr--;
1396		} else if (path->reada == READA_FORWARD ||
1397			   path->reada == READA_FORWARD_ALWAYS) {
1398			nr++;
1399			if (nr >= nritems)
1400				break;
1401		}
1402		if (path->reada == READA_BACK && objectid) {
1403			btrfs_node_key(node, &disk_key, nr);
1404			if (btrfs_disk_key_objectid(&disk_key) != objectid)
1405				break;
1406		}
1407		search = btrfs_node_blockptr(node, nr);
1408		if (path->reada == READA_FORWARD_ALWAYS ||
1409		    (search <= target && target - search <= 65536) ||
1410		    (search > target && search - target <= 65536)) {
1411			btrfs_readahead_node_child(node, nr);
1412			nread += blocksize;
1413		}
1414		nscan++;
1415		if (nread > nread_max || nscan > 32)
1416			break;
1417	}
1418}
1419
1420static noinline void reada_for_balance(struct btrfs_path *path, int level)
 
1421{
1422	struct extent_buffer *parent;
1423	int slot;
1424	int nritems;
 
 
 
 
 
1425
1426	parent = path->nodes[level + 1];
1427	if (!parent)
1428		return;
1429
1430	nritems = btrfs_header_nritems(parent);
1431	slot = path->slots[level + 1];
1432
1433	if (slot > 0)
1434		btrfs_readahead_node_child(parent, slot - 1);
1435	if (slot + 1 < nritems)
1436		btrfs_readahead_node_child(parent, slot + 1);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1437}
1438
1439
1440/*
1441 * when we walk down the tree, it is usually safe to unlock the higher layers
1442 * in the tree.  The exceptions are when our path goes through slot 0, because
1443 * operations on the tree might require changing key pointers higher up in the
1444 * tree.
1445 *
1446 * callers might also have set path->keep_locks, which tells this code to keep
1447 * the lock if the path points to the last slot in the block.  This is part of
1448 * walking through the tree, and selecting the next slot in the higher block.
1449 *
1450 * lowest_unlock sets the lowest level in the tree we're allowed to unlock.  so
1451 * if lowest_unlock is 1, level 0 won't be unlocked
1452 */
1453static noinline void unlock_up(struct btrfs_path *path, int level,
1454			       int lowest_unlock, int min_write_lock_level,
1455			       int *write_lock_level)
1456{
1457	int i;
1458	int skip_level = level;
1459	bool check_skip = true;
 
1460
1461	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1462		if (!path->nodes[i])
1463			break;
1464		if (!path->locks[i])
1465			break;
1466
1467		if (check_skip) {
1468			if (path->slots[i] == 0) {
 
 
 
 
 
 
1469				skip_level = i + 1;
1470				continue;
1471			}
1472
1473			if (path->keep_locks) {
1474				u32 nritems;
1475
1476				nritems = btrfs_header_nritems(path->nodes[i]);
1477				if (nritems < 1 || path->slots[i] >= nritems - 1) {
1478					skip_level = i + 1;
1479					continue;
1480				}
1481			}
1482		}
 
 
1483
1484		if (i >= lowest_unlock && i > skip_level) {
1485			check_skip = false;
1486			btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
1487			path->locks[i] = 0;
1488			if (write_lock_level &&
1489			    i > min_write_lock_level &&
1490			    i <= *write_lock_level) {
1491				*write_lock_level = i - 1;
1492			}
1493		}
1494	}
1495}
1496
1497/*
1498 * Helper function for btrfs_search_slot() and other functions that do a search
1499 * on a btree. The goal is to find a tree block in the cache (the radix tree at
1500 * fs_info->buffer_radix), but if we can't find it, or it's not up to date, read
1501 * its pages from disk.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1502 *
1503 * Returns -EAGAIN, with the path unlocked, if the caller needs to repeat the
1504 * whole btree search, starting again from the current root node.
1505 */
1506static int
1507read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
1508		      struct extent_buffer **eb_ret, int slot,
1509		      const struct btrfs_key *key)
1510{
1511	struct btrfs_fs_info *fs_info = root->fs_info;
1512	struct btrfs_tree_parent_check check = { 0 };
1513	u64 blocknr;
1514	struct extent_buffer *tmp = NULL;
1515	int ret = 0;
 
 
 
1516	int parent_level;
1517	int err;
1518	bool read_tmp = false;
1519	bool tmp_locked = false;
1520	bool path_released = false;
1521
1522	blocknr = btrfs_node_blockptr(*eb_ret, slot);
1523	parent_level = btrfs_header_level(*eb_ret);
1524	btrfs_node_key_to_cpu(*eb_ret, &check.first_key, slot);
1525	check.has_first_key = true;
1526	check.level = parent_level - 1;
1527	check.transid = btrfs_node_ptr_generation(*eb_ret, slot);
1528	check.owner_root = btrfs_root_id(root);
1529
1530	/*
1531	 * If we need to read an extent buffer from disk and we are holding locks
1532	 * on upper level nodes, we unlock all the upper nodes before reading the
1533	 * extent buffer, and then return -EAGAIN to the caller as it needs to
1534	 * restart the search. We don't release the lock on the current level
1535	 * because we need to walk this node to figure out which blocks to read.
1536	 */
1537	tmp = find_extent_buffer(fs_info, blocknr);
1538	if (tmp) {
1539		if (p->reada == READA_FORWARD_ALWAYS)
1540			reada_for_search(fs_info, p, parent_level, slot, key->objectid);
1541
1542		/* first we do an atomic uptodate check */
1543		if (btrfs_buffer_uptodate(tmp, check.transid, 1) > 0) {
1544			/*
1545			 * Do extra check for first_key, eb can be stale due to
1546			 * being cached, read from scrub, or have multiple
1547			 * parents (shared tree blocks).
1548			 */
1549			if (btrfs_verify_level_key(tmp, &check)) {
1550				ret = -EUCLEAN;
1551				goto out;
1552			}
1553			*eb_ret = tmp;
1554			tmp = NULL;
1555			ret = 0;
1556			goto out;
1557		}
1558
1559		if (p->nowait) {
1560			ret = -EAGAIN;
1561			goto out;
1562		}
1563
1564		if (!p->skip_locking) {
1565			btrfs_unlock_up_safe(p, parent_level + 1);
1566			btrfs_maybe_reset_lockdep_class(root, tmp);
1567			tmp_locked = true;
1568			btrfs_tree_read_lock(tmp);
1569			btrfs_release_path(p);
1570			ret = -EAGAIN;
1571			path_released = true;
1572		}
1573
1574		/* Now we're allowed to do a blocking uptodate check. */
1575		err = btrfs_read_extent_buffer(tmp, &check);
1576		if (err) {
1577			ret = err;
1578			goto out;
1579		}
 
1580
1581		if (ret == 0) {
1582			ASSERT(!tmp_locked);
 
1583			*eb_ret = tmp;
1584			tmp = NULL;
1585		}
1586		goto out;
1587	} else if (p->nowait) {
1588		ret = -EAGAIN;
1589		goto out;
1590	}
1591
1592	if (!p->skip_locking) {
1593		btrfs_unlock_up_safe(p, parent_level + 1);
1594		ret = -EAGAIN;
1595	}
1596
1597	if (p->reada != READA_NONE)
1598		reada_for_search(fs_info, p, parent_level, slot, key->objectid);
1599
1600	tmp = btrfs_find_create_tree_block(fs_info, blocknr, check.owner_root, check.level);
1601	if (IS_ERR(tmp)) {
1602		ret = PTR_ERR(tmp);
1603		tmp = NULL;
1604		goto out;
1605	}
1606	read_tmp = true;
1607
1608	if (!p->skip_locking) {
1609		ASSERT(ret == -EAGAIN);
1610		btrfs_maybe_reset_lockdep_class(root, tmp);
1611		tmp_locked = true;
1612		btrfs_tree_read_lock(tmp);
1613		btrfs_release_path(p);
1614		path_released = true;
1615	}
1616
1617	/* Now we're allowed to do a blocking uptodate check. */
1618	err = btrfs_read_extent_buffer(tmp, &check);
1619	if (err) {
1620		ret = err;
1621		goto out;
1622	}
1623
1624	/*
1625	 * If the read above didn't mark this buffer up to date,
1626	 * it will never end up being up to date.  Set ret to EIO now
1627	 * and give up so that our caller doesn't loop forever
1628	 * on our EAGAINs.
 
1629	 */
1630	if (!extent_buffer_uptodate(tmp)) {
1631		ret = -EIO;
1632		goto out;
1633	}
1634
1635	if (ret == 0) {
1636		ASSERT(!tmp_locked);
1637		*eb_ret = tmp;
1638		tmp = NULL;
1639	}
1640out:
1641	if (tmp) {
1642		if (tmp_locked)
1643			btrfs_tree_read_unlock(tmp);
1644		if (read_tmp && ret && ret != -EAGAIN)
1645			free_extent_buffer_stale(tmp);
1646		else
1647			free_extent_buffer(tmp);
 
 
 
 
 
 
1648	}
1649	if (ret && !path_released)
1650		btrfs_release_path(p);
1651
 
1652	return ret;
1653}
1654
1655/*
1656 * helper function for btrfs_search_slot.  This does all of the checks
1657 * for node-level blocks and does any balancing required based on
1658 * the ins_len.
1659 *
1660 * If no extra work was required, zero is returned.  If we had to
1661 * drop the path, -EAGAIN is returned and btrfs_search_slot must
1662 * start over
1663 */
1664static int
1665setup_nodes_for_search(struct btrfs_trans_handle *trans,
1666		       struct btrfs_root *root, struct btrfs_path *p,
1667		       struct extent_buffer *b, int level, int ins_len,
1668		       int *write_lock_level)
1669{
1670	struct btrfs_fs_info *fs_info = root->fs_info;
1671	int ret = 0;
1672
1673	if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1674	    BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
 
1675
1676		if (*write_lock_level < level + 1) {
1677			*write_lock_level = level + 1;
1678			btrfs_release_path(p);
1679			return -EAGAIN;
1680		}
1681
1682		reada_for_balance(p, level);
1683		ret = split_node(trans, root, p, level);
 
 
1684
 
 
 
 
 
1685		b = p->nodes[level];
1686	} else if (ins_len < 0 && btrfs_header_nritems(b) <
1687		   BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
 
1688
1689		if (*write_lock_level < level + 1) {
1690			*write_lock_level = level + 1;
1691			btrfs_release_path(p);
1692			return -EAGAIN;
1693		}
1694
1695		reada_for_balance(p, level);
1696		ret = balance_level(trans, root, p, level);
1697		if (ret)
1698			return ret;
1699
 
 
 
 
1700		b = p->nodes[level];
1701		if (!b) {
1702			btrfs_release_path(p);
1703			return -EAGAIN;
1704		}
1705		BUG_ON(btrfs_header_nritems(b) == 1);
1706	}
 
 
 
 
 
1707	return ret;
1708}
1709
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1710int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
1711		u64 iobjectid, u64 ioff, u8 key_type,
1712		struct btrfs_key *found_key)
1713{
1714	int ret;
1715	struct btrfs_key key;
1716	struct extent_buffer *eb;
1717
1718	ASSERT(path);
1719	ASSERT(found_key);
1720
1721	key.type = key_type;
1722	key.objectid = iobjectid;
1723	key.offset = ioff;
1724
1725	ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1726	if (ret < 0)
1727		return ret;
1728
1729	eb = path->nodes[0];
1730	if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1731		ret = btrfs_next_leaf(fs_root, path);
1732		if (ret)
1733			return ret;
1734		eb = path->nodes[0];
1735	}
1736
1737	btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1738	if (found_key->type != key.type ||
1739			found_key->objectid != key.objectid)
1740		return 1;
1741
1742	return 0;
1743}
1744
1745static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
1746							struct btrfs_path *p,
1747							int write_lock_level)
1748{
1749	struct extent_buffer *b;
1750	int root_lock = 0;
1751	int level = 0;
1752
1753	if (p->search_commit_root) {
1754		b = root->commit_root;
1755		atomic_inc(&b->refs);
1756		level = btrfs_header_level(b);
1757		/*
1758		 * Ensure that all callers have set skip_locking when
1759		 * p->search_commit_root = 1.
1760		 */
1761		ASSERT(p->skip_locking == 1);
1762
1763		goto out;
1764	}
1765
1766	if (p->skip_locking) {
1767		b = btrfs_root_node(root);
1768		level = btrfs_header_level(b);
1769		goto out;
1770	}
1771
1772	/* We try very hard to do read locks on the root */
1773	root_lock = BTRFS_READ_LOCK;
1774
1775	/*
1776	 * If the level is set to maximum, we can skip trying to get the read
1777	 * lock.
1778	 */
1779	if (write_lock_level < BTRFS_MAX_LEVEL) {
1780		/*
1781		 * We don't know the level of the root node until we actually
1782		 * have it read locked
1783		 */
1784		if (p->nowait) {
1785			b = btrfs_try_read_lock_root_node(root);
1786			if (IS_ERR(b))
1787				return b;
1788		} else {
1789			b = btrfs_read_lock_root_node(root);
1790		}
1791		level = btrfs_header_level(b);
1792		if (level > write_lock_level)
1793			goto out;
1794
1795		/* Whoops, must trade for write lock */
1796		btrfs_tree_read_unlock(b);
1797		free_extent_buffer(b);
1798	}
1799
1800	b = btrfs_lock_root_node(root);
1801	root_lock = BTRFS_WRITE_LOCK;
1802
1803	/* The level might have changed, check again */
1804	level = btrfs_header_level(b);
1805
1806out:
1807	/*
1808	 * The root may have failed to write out at some point, and thus is no
1809	 * longer valid, return an error in this case.
1810	 */
1811	if (!extent_buffer_uptodate(b)) {
1812		if (root_lock)
1813			btrfs_tree_unlock_rw(b, root_lock);
1814		free_extent_buffer(b);
1815		return ERR_PTR(-EIO);
1816	}
1817
1818	p->nodes[level] = b;
1819	if (!p->skip_locking)
1820		p->locks[level] = root_lock;
1821	/*
1822	 * Callers are responsible for dropping b's references.
1823	 */
1824	return b;
1825}
1826
1827/*
1828 * Replace the extent buffer at the lowest level of the path with a cloned
1829 * version. The purpose is to be able to use it safely, after releasing the
1830 * commit root semaphore, even if relocation is happening in parallel, the
1831 * transaction used for relocation is committed and the extent buffer is
1832 * reallocated in the next transaction.
1833 *
1834 * This is used in a context where the caller does not prevent transaction
1835 * commits from happening, either by holding a transaction handle or holding
1836 * some lock, while it's doing searches through a commit root.
1837 * At the moment it's only used for send operations.
1838 */
1839static int finish_need_commit_sem_search(struct btrfs_path *path)
1840{
1841	const int i = path->lowest_level;
1842	const int slot = path->slots[i];
1843	struct extent_buffer *lowest = path->nodes[i];
1844	struct extent_buffer *clone;
1845
1846	ASSERT(path->need_commit_sem);
1847
1848	if (!lowest)
1849		return 0;
1850
1851	lockdep_assert_held_read(&lowest->fs_info->commit_root_sem);
1852
1853	clone = btrfs_clone_extent_buffer(lowest);
1854	if (!clone)
1855		return -ENOMEM;
1856
1857	btrfs_release_path(path);
1858	path->nodes[i] = clone;
1859	path->slots[i] = slot;
1860
1861	return 0;
1862}
1863
1864static inline int search_for_key_slot(struct extent_buffer *eb,
1865				      int search_low_slot,
1866				      const struct btrfs_key *key,
1867				      int prev_cmp,
1868				      int *slot)
1869{
1870	/*
1871	 * If a previous call to btrfs_bin_search() on a parent node returned an
1872	 * exact match (prev_cmp == 0), we can safely assume the target key will
1873	 * always be at slot 0 on lower levels, since each key pointer
1874	 * (struct btrfs_key_ptr) refers to the lowest key accessible from the
1875	 * subtree it points to. Thus we can skip searching lower levels.
1876	 */
1877	if (prev_cmp == 0) {
1878		*slot = 0;
1879		return 0;
1880	}
1881
1882	return btrfs_bin_search(eb, search_low_slot, key, slot);
1883}
1884
1885static int search_leaf(struct btrfs_trans_handle *trans,
1886		       struct btrfs_root *root,
1887		       const struct btrfs_key *key,
1888		       struct btrfs_path *path,
1889		       int ins_len,
1890		       int prev_cmp)
1891{
1892	struct extent_buffer *leaf = path->nodes[0];
1893	int leaf_free_space = -1;
1894	int search_low_slot = 0;
1895	int ret;
1896	bool do_bin_search = true;
1897
1898	/*
1899	 * If we are doing an insertion, the leaf has enough free space and the
1900	 * destination slot for the key is not slot 0, then we can unlock our
1901	 * write lock on the parent, and any other upper nodes, before doing the
1902	 * binary search on the leaf (with search_for_key_slot()), allowing other
1903	 * tasks to lock the parent and any other upper nodes.
1904	 */
1905	if (ins_len > 0) {
1906		/*
1907		 * Cache the leaf free space, since we will need it later and it
1908		 * will not change until then.
1909		 */
1910		leaf_free_space = btrfs_leaf_free_space(leaf);
1911
1912		/*
1913		 * !path->locks[1] means we have a single node tree, the leaf is
1914		 * the root of the tree.
1915		 */
1916		if (path->locks[1] && leaf_free_space >= ins_len) {
1917			struct btrfs_disk_key first_key;
1918
1919			ASSERT(btrfs_header_nritems(leaf) > 0);
1920			btrfs_item_key(leaf, &first_key, 0);
1921
1922			/*
1923			 * Doing the extra comparison with the first key is cheap,
1924			 * taking into account that the first key is very likely
1925			 * already in a cache line because it immediately follows
1926			 * the extent buffer's header and we have recently accessed
1927			 * the header's level field.
1928			 */
1929			ret = btrfs_comp_keys(&first_key, key);
1930			if (ret < 0) {
1931				/*
1932				 * The first key is smaller than the key we want
1933				 * to insert, so we are safe to unlock all upper
1934				 * nodes and we have to do the binary search.
1935				 *
1936				 * We do use btrfs_unlock_up_safe() and not
1937				 * unlock_up() because the later does not unlock
1938				 * nodes with a slot of 0 - we can safely unlock
1939				 * any node even if its slot is 0 since in this
1940				 * case the key does not end up at slot 0 of the
1941				 * leaf and there's no need to split the leaf.
1942				 */
1943				btrfs_unlock_up_safe(path, 1);
1944				search_low_slot = 1;
1945			} else {
1946				/*
1947				 * The first key is >= then the key we want to
1948				 * insert, so we can skip the binary search as
1949				 * the target key will be at slot 0.
1950				 *
1951				 * We can not unlock upper nodes when the key is
1952				 * less than the first key, because we will need
1953				 * to update the key at slot 0 of the parent node
1954				 * and possibly of other upper nodes too.
1955				 * If the key matches the first key, then we can
1956				 * unlock all the upper nodes, using
1957				 * btrfs_unlock_up_safe() instead of unlock_up()
1958				 * as stated above.
1959				 */
1960				if (ret == 0)
1961					btrfs_unlock_up_safe(path, 1);
1962				/*
1963				 * ret is already 0 or 1, matching the result of
1964				 * a btrfs_bin_search() call, so there is no need
1965				 * to adjust it.
1966				 */
1967				do_bin_search = false;
1968				path->slots[0] = 0;
1969			}
1970		}
1971	}
1972
1973	if (do_bin_search) {
1974		ret = search_for_key_slot(leaf, search_low_slot, key,
1975					  prev_cmp, &path->slots[0]);
1976		if (ret < 0)
1977			return ret;
1978	}
1979
1980	if (ins_len > 0) {
1981		/*
1982		 * Item key already exists. In this case, if we are allowed to
1983		 * insert the item (for example, in dir_item case, item key
1984		 * collision is allowed), it will be merged with the original
1985		 * item. Only the item size grows, no new btrfs item will be
1986		 * added. If search_for_extension is not set, ins_len already
1987		 * accounts the size btrfs_item, deduct it here so leaf space
1988		 * check will be correct.
1989		 */
1990		if (ret == 0 && !path->search_for_extension) {
1991			ASSERT(ins_len >= sizeof(struct btrfs_item));
1992			ins_len -= sizeof(struct btrfs_item);
1993		}
1994
1995		ASSERT(leaf_free_space >= 0);
1996
1997		if (leaf_free_space < ins_len) {
1998			int err;
1999
2000			err = split_leaf(trans, root, key, path, ins_len,
2001					 (ret == 0));
2002			ASSERT(err <= 0);
2003			if (WARN_ON(err > 0))
2004				err = -EUCLEAN;
2005			if (err)
2006				ret = err;
2007		}
2008	}
2009
2010	return ret;
2011}
2012
2013/*
2014 * Look for a key in a tree and perform necessary modifications to preserve
2015 * tree invariants.
2016 *
2017 * @trans:	Handle of transaction, used when modifying the tree
2018 * @p:		Holds all btree nodes along the search path
2019 * @root:	The root node of the tree
2020 * @key:	The key we are looking for
2021 * @ins_len:	Indicates purpose of search:
2022 *              >0  for inserts it's size of item inserted (*)
2023 *              <0  for deletions
2024 *               0  for plain searches, not modifying the tree
2025 *
2026 *              (*) If size of item inserted doesn't include
2027 *              sizeof(struct btrfs_item), then p->search_for_extension must
2028 *              be set.
2029 * @cow:	boolean should CoW operations be performed. Must always be 1
2030 *		when modifying the tree.
2031 *
2032 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2033 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2034 *
2035 * If @key is found, 0 is returned and you can find the item in the leaf level
2036 * of the path (level 0)
2037 *
2038 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2039 * points to the slot where it should be inserted
2040 *
2041 * If an error is encountered while searching the tree a negative error number
2042 * is returned
2043 */
2044int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2045		      const struct btrfs_key *key, struct btrfs_path *p,
2046		      int ins_len, int cow)
2047{
2048	struct btrfs_fs_info *fs_info;
2049	struct extent_buffer *b;
2050	int slot;
2051	int ret;
2052	int err;
2053	int level;
2054	int lowest_unlock = 1;
 
2055	/* everything at write_lock_level or lower must be write locked */
2056	int write_lock_level = 0;
2057	u8 lowest_level = 0;
2058	int min_write_lock_level;
2059	int prev_cmp;
2060
2061	if (!root)
2062		return -EINVAL;
2063
2064	fs_info = root->fs_info;
2065	might_sleep();
2066
2067	lowest_level = p->lowest_level;
2068	WARN_ON(lowest_level && ins_len > 0);
2069	WARN_ON(p->nodes[0] != NULL);
2070	BUG_ON(!cow && ins_len);
2071
2072	/*
2073	 * For now only allow nowait for read only operations.  There's no
2074	 * strict reason why we can't, we just only need it for reads so it's
2075	 * only implemented for reads.
2076	 */
2077	ASSERT(!p->nowait || !cow);
2078
2079	if (ins_len < 0) {
2080		lowest_unlock = 2;
2081
2082		/* when we are removing items, we might have to go up to level
2083		 * two as we update tree pointers  Make sure we keep write
2084		 * for those levels as well
2085		 */
2086		write_lock_level = 2;
2087	} else if (ins_len > 0) {
2088		/*
2089		 * for inserting items, make sure we have a write lock on
2090		 * level 1 so we can update keys
2091		 */
2092		write_lock_level = 1;
2093	}
2094
2095	if (!cow)
2096		write_lock_level = -1;
2097
2098	if (cow && (p->keep_locks || p->lowest_level))
2099		write_lock_level = BTRFS_MAX_LEVEL;
2100
2101	min_write_lock_level = write_lock_level;
2102
2103	if (p->need_commit_sem) {
2104		ASSERT(p->search_commit_root);
2105		if (p->nowait) {
2106			if (!down_read_trylock(&fs_info->commit_root_sem))
2107				return -EAGAIN;
2108		} else {
2109			down_read(&fs_info->commit_root_sem);
2110		}
2111	}
2112
2113again:
2114	prev_cmp = -1;
2115	b = btrfs_search_slot_get_root(root, p, write_lock_level);
2116	if (IS_ERR(b)) {
2117		ret = PTR_ERR(b);
2118		goto done;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2119	}
 
 
 
2120
2121	while (b) {
2122		int dec = 0;
2123
2124		level = btrfs_header_level(b);
2125
 
 
 
 
2126		if (cow) {
2127			bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2128
2129			/*
2130			 * if we don't really need to cow this block
2131			 * then we don't want to set the path blocking,
2132			 * so we test it here
2133			 */
2134			if (!should_cow_block(trans, root, b))
 
2135				goto cow_done;
 
2136
2137			/*
2138			 * must have write locks on this node and the
2139			 * parent
2140			 */
2141			if (level > write_lock_level ||
2142			    (level + 1 > write_lock_level &&
2143			    level + 1 < BTRFS_MAX_LEVEL &&
2144			    p->nodes[level + 1])) {
2145				write_lock_level = level + 1;
2146				btrfs_release_path(p);
2147				goto again;
2148			}
2149
 
2150			if (last_level)
2151				err = btrfs_cow_block(trans, root, b, NULL, 0,
2152						      &b,
2153						      BTRFS_NESTING_COW);
2154			else
2155				err = btrfs_cow_block(trans, root, b,
2156						      p->nodes[level + 1],
2157						      p->slots[level + 1], &b,
2158						      BTRFS_NESTING_COW);
2159			if (err) {
2160				ret = err;
2161				goto done;
2162			}
2163		}
2164cow_done:
2165		p->nodes[level] = b;
 
2166
2167		/*
2168		 * we have a lock on b and as long as we aren't changing
2169		 * the tree, there is no way to for the items in b to change.
2170		 * It is safe to drop the lock on our parent before we
2171		 * go through the expensive btree search on b.
2172		 *
2173		 * If we're inserting or deleting (ins_len != 0), then we might
2174		 * be changing slot zero, which may require changing the parent.
2175		 * So, we can't drop the lock until after we know which slot
2176		 * we're operating on.
2177		 */
2178		if (!ins_len && !p->keep_locks) {
2179			int u = level + 1;
2180
2181			if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2182				btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2183				p->locks[u] = 0;
2184			}
2185		}
2186
2187		if (level == 0) {
2188			if (ins_len > 0)
2189				ASSERT(write_lock_level >= 1);
2190
2191			ret = search_leaf(trans, root, key, p, ins_len, prev_cmp);
2192			if (!p->search_for_split)
2193				unlock_up(p, level, lowest_unlock,
2194					  min_write_lock_level, NULL);
2195			goto done;
2196		}
2197
2198		ret = search_for_key_slot(b, 0, key, prev_cmp, &slot);
2199		if (ret < 0)
2200			goto done;
2201		prev_cmp = ret;
2202
2203		if (ret && slot > 0) {
2204			dec = 1;
2205			slot--;
2206		}
2207		p->slots[level] = slot;
2208		err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
2209					     &write_lock_level);
2210		if (err == -EAGAIN)
2211			goto again;
2212		if (err) {
2213			ret = err;
2214			goto done;
2215		}
2216		b = p->nodes[level];
2217		slot = p->slots[level];
2218
2219		/*
2220		 * Slot 0 is special, if we change the key we have to update
2221		 * the parent pointer which means we must have a write lock on
2222		 * the parent
2223		 */
2224		if (slot == 0 && ins_len && write_lock_level < level + 1) {
2225			write_lock_level = level + 1;
2226			btrfs_release_path(p);
2227			goto again;
2228		}
2229
2230		unlock_up(p, level, lowest_unlock, min_write_lock_level,
2231			  &write_lock_level);
2232
2233		if (level == lowest_level) {
2234			if (dec)
2235				p->slots[level]++;
2236			goto done;
2237		}
 
 
 
 
 
 
 
2238
2239		err = read_block_for_search(root, p, &b, slot, key);
2240		if (err == -EAGAIN && !p->nowait)
2241			goto again;
2242		if (err) {
2243			ret = err;
2244			goto done;
2245		}
2246
2247		if (!p->skip_locking) {
2248			level = btrfs_header_level(b);
 
 
 
2249
2250			btrfs_maybe_reset_lockdep_class(root, b);
 
 
 
 
 
 
 
2251
2252			if (level <= write_lock_level) {
2253				btrfs_tree_lock(b);
2254				p->locks[level] = BTRFS_WRITE_LOCK;
2255			} else {
2256				if (p->nowait) {
2257					if (!btrfs_try_tree_read_lock(b)) {
2258						free_extent_buffer(b);
2259						ret = -EAGAIN;
2260						goto done;
2261					}
 
2262				} else {
2263					btrfs_tree_read_lock(b);
 
 
 
 
 
 
 
2264				}
2265				p->locks[level] = BTRFS_READ_LOCK;
2266			}
2267			p->nodes[level] = b;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2268		}
2269	}
2270	ret = 1;
2271done:
 
 
 
 
 
 
2272	if (ret < 0 && !p->skip_release_on_error)
2273		btrfs_release_path(p);
2274
2275	if (p->need_commit_sem) {
2276		int ret2;
2277
2278		ret2 = finish_need_commit_sem_search(p);
2279		up_read(&fs_info->commit_root_sem);
2280		if (ret2)
2281			ret = ret2;
2282	}
2283
2284	return ret;
2285}
2286ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
2287
2288/*
2289 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2290 * current state of the tree together with the operations recorded in the tree
2291 * modification log to search for the key in a previous version of this tree, as
2292 * denoted by the time_seq parameter.
2293 *
2294 * Naturally, there is no support for insert, delete or cow operations.
2295 *
2296 * The resulting path and return value will be set up as if we called
2297 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2298 */
2299int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2300			  struct btrfs_path *p, u64 time_seq)
2301{
2302	struct btrfs_fs_info *fs_info = root->fs_info;
2303	struct extent_buffer *b;
2304	int slot;
2305	int ret;
2306	int err;
2307	int level;
2308	int lowest_unlock = 1;
2309	u8 lowest_level = 0;
 
2310
2311	lowest_level = p->lowest_level;
2312	WARN_ON(p->nodes[0] != NULL);
2313	ASSERT(!p->nowait);
2314
2315	if (p->search_commit_root) {
2316		BUG_ON(time_seq);
2317		return btrfs_search_slot(NULL, root, key, p, 0, 0);
2318	}
2319
2320again:
2321	b = btrfs_get_old_root(root, time_seq);
2322	if (!b) {
2323		ret = -EIO;
2324		goto done;
2325	}
2326	level = btrfs_header_level(b);
2327	p->locks[level] = BTRFS_READ_LOCK;
2328
2329	while (b) {
2330		int dec = 0;
2331
2332		level = btrfs_header_level(b);
2333		p->nodes[level] = b;
 
2334
2335		/*
2336		 * we have a lock on b and as long as we aren't changing
2337		 * the tree, there is no way to for the items in b to change.
2338		 * It is safe to drop the lock on our parent before we
2339		 * go through the expensive btree search on b.
2340		 */
2341		btrfs_unlock_up_safe(p, level + 1);
2342
2343		ret = btrfs_bin_search(b, 0, key, &slot);
2344		if (ret < 0)
2345			goto done;
 
 
 
2346
2347		if (level == 0) {
 
 
 
 
 
2348			p->slots[level] = slot;
2349			unlock_up(p, level, lowest_unlock, 0, NULL);
2350			goto done;
2351		}
2352
2353		if (ret && slot > 0) {
2354			dec = 1;
2355			slot--;
2356		}
2357		p->slots[level] = slot;
2358		unlock_up(p, level, lowest_unlock, 0, NULL);
2359
2360		if (level == lowest_level) {
2361			if (dec)
2362				p->slots[level]++;
2363			goto done;
2364		}
2365
2366		err = read_block_for_search(root, p, &b, slot, key);
2367		if (err == -EAGAIN && !p->nowait)
2368			goto again;
2369		if (err) {
2370			ret = err;
2371			goto done;
2372		}
 
2373
2374		level = btrfs_header_level(b);
2375		btrfs_tree_read_lock(b);
2376		b = btrfs_tree_mod_log_rewind(fs_info, b, time_seq);
2377		if (!b) {
2378			ret = -ENOMEM;
 
 
 
 
 
 
 
 
 
 
 
 
 
2379			goto done;
2380		}
2381		p->locks[level] = BTRFS_READ_LOCK;
2382		p->nodes[level] = b;
2383	}
2384	ret = 1;
2385done:
 
 
2386	if (ret < 0)
2387		btrfs_release_path(p);
2388
2389	return ret;
2390}
2391
2392/*
2393 * Search the tree again to find a leaf with smaller keys.
2394 * Returns 0 if it found something.
2395 * Returns 1 if there are no smaller keys.
2396 * Returns < 0 on error.
2397 *
2398 * This may release the path, and so you may lose any locks held at the
2399 * time you call it.
2400 */
2401static int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2402{
2403	struct btrfs_key key;
2404	struct btrfs_key orig_key;
2405	struct btrfs_disk_key found_key;
2406	int ret;
2407
2408	btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
2409	orig_key = key;
2410
2411	if (key.offset > 0) {
2412		key.offset--;
2413	} else if (key.type > 0) {
2414		key.type--;
2415		key.offset = (u64)-1;
2416	} else if (key.objectid > 0) {
2417		key.objectid--;
2418		key.type = (u8)-1;
2419		key.offset = (u64)-1;
2420	} else {
2421		return 1;
2422	}
2423
2424	btrfs_release_path(path);
2425	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2426	if (ret <= 0)
2427		return ret;
2428
2429	/*
2430	 * Previous key not found. Even if we were at slot 0 of the leaf we had
2431	 * before releasing the path and calling btrfs_search_slot(), we now may
2432	 * be in a slot pointing to the same original key - this can happen if
2433	 * after we released the path, one of more items were moved from a
2434	 * sibling leaf into the front of the leaf we had due to an insertion
2435	 * (see push_leaf_right()).
2436	 * If we hit this case and our slot is > 0 and just decrement the slot
2437	 * so that the caller does not process the same key again, which may or
2438	 * may not break the caller, depending on its logic.
2439	 */
2440	if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) {
2441		btrfs_item_key(path->nodes[0], &found_key, path->slots[0]);
2442		ret = btrfs_comp_keys(&found_key, &orig_key);
2443		if (ret == 0) {
2444			if (path->slots[0] > 0) {
2445				path->slots[0]--;
2446				return 0;
2447			}
2448			/*
2449			 * At slot 0, same key as before, it means orig_key is
2450			 * the lowest, leftmost, key in the tree. We're done.
2451			 */
2452			return 1;
2453		}
2454	}
2455
2456	btrfs_item_key(path->nodes[0], &found_key, 0);
2457	ret = btrfs_comp_keys(&found_key, &key);
2458	/*
2459	 * We might have had an item with the previous key in the tree right
2460	 * before we released our path. And after we released our path, that
2461	 * item might have been pushed to the first slot (0) of the leaf we
2462	 * were holding due to a tree balance. Alternatively, an item with the
2463	 * previous key can exist as the only element of a leaf (big fat item).
2464	 * Therefore account for these 2 cases, so that our callers (like
2465	 * btrfs_previous_item) don't miss an existing item with a key matching
2466	 * the previous key we computed above.
2467	 */
2468	if (ret <= 0)
2469		return 0;
2470	return 1;
2471}
2472
2473/*
2474 * helper to use instead of search slot if no exact match is needed but
2475 * instead the next or previous item should be returned.
2476 * When find_higher is true, the next higher item is returned, the next lower
2477 * otherwise.
2478 * When return_any and find_higher are both true, and no higher item is found,
2479 * return the next lower instead.
2480 * When return_any is true and find_higher is false, and no lower item is found,
2481 * return the next higher instead.
2482 * It returns 0 if any item is found, 1 if none is found (tree empty), and
2483 * < 0 on error
2484 */
2485int btrfs_search_slot_for_read(struct btrfs_root *root,
2486			       const struct btrfs_key *key,
2487			       struct btrfs_path *p, int find_higher,
2488			       int return_any)
2489{
2490	int ret;
2491	struct extent_buffer *leaf;
2492
2493again:
2494	ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2495	if (ret <= 0)
2496		return ret;
2497	/*
2498	 * a return value of 1 means the path is at the position where the
2499	 * item should be inserted. Normally this is the next bigger item,
2500	 * but in case the previous item is the last in a leaf, path points
2501	 * to the first free slot in the previous leaf, i.e. at an invalid
2502	 * item.
2503	 */
2504	leaf = p->nodes[0];
2505
2506	if (find_higher) {
2507		if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2508			ret = btrfs_next_leaf(root, p);
2509			if (ret <= 0)
2510				return ret;
2511			if (!return_any)
2512				return 1;
2513			/*
2514			 * no higher item found, return the next
2515			 * lower instead
2516			 */
2517			return_any = 0;
2518			find_higher = 0;
2519			btrfs_release_path(p);
2520			goto again;
2521		}
2522	} else {
2523		if (p->slots[0] == 0) {
2524			ret = btrfs_prev_leaf(root, p);
2525			if (ret < 0)
2526				return ret;
2527			if (!ret) {
2528				leaf = p->nodes[0];
2529				if (p->slots[0] == btrfs_header_nritems(leaf))
2530					p->slots[0]--;
2531				return 0;
2532			}
2533			if (!return_any)
2534				return 1;
2535			/*
2536			 * no lower item found, return the next
2537			 * higher instead
2538			 */
2539			return_any = 0;
2540			find_higher = 1;
2541			btrfs_release_path(p);
2542			goto again;
2543		} else {
2544			--p->slots[0];
2545		}
2546	}
2547	return 0;
2548}
2549
2550/*
2551 * Execute search and call btrfs_previous_item to traverse backwards if the item
2552 * was not found.
2553 *
2554 * Return 0 if found, 1 if not found and < 0 if error.
2555 */
2556int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,
2557			   struct btrfs_path *path)
2558{
2559	int ret;
2560
2561	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
2562	if (ret > 0)
2563		ret = btrfs_previous_item(root, path, key->objectid, key->type);
2564
2565	if (ret == 0)
2566		btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2567
2568	return ret;
2569}
2570
2571/*
2572 * Search for a valid slot for the given path.
2573 *
2574 * @root:	The root node of the tree.
2575 * @key:	Will contain a valid item if found.
2576 * @path:	The starting point to validate the slot.
2577 *
2578 * Return: 0  if the item is valid
2579 *         1  if not found
2580 *         <0 if error.
2581 */
2582int btrfs_get_next_valid_item(struct btrfs_root *root, struct btrfs_key *key,
2583			      struct btrfs_path *path)
2584{
2585	if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
2586		int ret;
2587
2588		ret = btrfs_next_leaf(root, path);
2589		if (ret)
2590			return ret;
2591	}
2592
2593	btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2594	return 0;
2595}
2596
2597/*
2598 * adjust the pointers going up the tree, starting at level
2599 * making sure the right key of each node is points to 'key'.
2600 * This is used after shifting pointers to the left, so it stops
2601 * fixing up pointers when a given leaf/node is not in slot 0 of the
2602 * higher levels
2603 *
2604 */
2605static void fixup_low_keys(struct btrfs_trans_handle *trans,
2606			   const struct btrfs_path *path,
2607			   const struct btrfs_disk_key *key, int level)
2608{
2609	int i;
2610	struct extent_buffer *t;
2611	int ret;
2612
2613	for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2614		int tslot = path->slots[i];
2615
2616		if (!path->nodes[i])
2617			break;
2618		t = path->nodes[i];
2619		ret = btrfs_tree_mod_log_insert_key(t, tslot,
2620						    BTRFS_MOD_LOG_KEY_REPLACE);
2621		BUG_ON(ret < 0);
2622		btrfs_set_node_key(t, key, tslot);
2623		btrfs_mark_buffer_dirty(trans, path->nodes[i]);
2624		if (tslot != 0)
2625			break;
2626	}
2627}
2628
2629/*
2630 * update item key.
2631 *
2632 * This function isn't completely safe. It's the caller's responsibility
2633 * that the new key won't break the order
2634 */
2635void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
2636			     const struct btrfs_path *path,
2637			     const struct btrfs_key *new_key)
2638{
2639	struct btrfs_fs_info *fs_info = trans->fs_info;
2640	struct btrfs_disk_key disk_key;
2641	struct extent_buffer *eb;
2642	int slot;
2643
2644	eb = path->nodes[0];
2645	slot = path->slots[0];
2646	if (slot > 0) {
2647		btrfs_item_key(eb, &disk_key, slot - 1);
2648		if (unlikely(btrfs_comp_keys(&disk_key, new_key) >= 0)) {
2649			btrfs_print_leaf(eb);
2650			btrfs_crit(fs_info,
2651		"slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2652				   slot, btrfs_disk_key_objectid(&disk_key),
2653				   btrfs_disk_key_type(&disk_key),
2654				   btrfs_disk_key_offset(&disk_key),
2655				   new_key->objectid, new_key->type,
2656				   new_key->offset);
2657			BUG();
2658		}
2659	}
2660	if (slot < btrfs_header_nritems(eb) - 1) {
2661		btrfs_item_key(eb, &disk_key, slot + 1);
2662		if (unlikely(btrfs_comp_keys(&disk_key, new_key) <= 0)) {
2663			btrfs_print_leaf(eb);
2664			btrfs_crit(fs_info,
2665		"slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2666				   slot, btrfs_disk_key_objectid(&disk_key),
2667				   btrfs_disk_key_type(&disk_key),
2668				   btrfs_disk_key_offset(&disk_key),
2669				   new_key->objectid, new_key->type,
2670				   new_key->offset);
2671			BUG();
2672		}
2673	}
2674
2675	btrfs_cpu_key_to_disk(&disk_key, new_key);
2676	btrfs_set_item_key(eb, &disk_key, slot);
2677	btrfs_mark_buffer_dirty(trans, eb);
2678	if (slot == 0)
2679		fixup_low_keys(trans, path, &disk_key, 1);
2680}
2681
2682/*
2683 * Check key order of two sibling extent buffers.
2684 *
2685 * Return true if something is wrong.
2686 * Return false if everything is fine.
2687 *
2688 * Tree-checker only works inside one tree block, thus the following
2689 * corruption can not be detected by tree-checker:
2690 *
2691 * Leaf @left			| Leaf @right
2692 * --------------------------------------------------------------
2693 * | 1 | 2 | 3 | 4 | 5 | f6 |   | 7 | 8 |
2694 *
2695 * Key f6 in leaf @left itself is valid, but not valid when the next
2696 * key in leaf @right is 7.
2697 * This can only be checked at tree block merge time.
2698 * And since tree checker has ensured all key order in each tree block
2699 * is correct, we only need to bother the last key of @left and the first
2700 * key of @right.
2701 */
2702static bool check_sibling_keys(const struct extent_buffer *left,
2703			       const struct extent_buffer *right)
2704{
2705	struct btrfs_key left_last;
2706	struct btrfs_key right_first;
2707	int level = btrfs_header_level(left);
2708	int nr_left = btrfs_header_nritems(left);
2709	int nr_right = btrfs_header_nritems(right);
2710
2711	/* No key to check in one of the tree blocks */
2712	if (!nr_left || !nr_right)
2713		return false;
2714
2715	if (level) {
2716		btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
2717		btrfs_node_key_to_cpu(right, &right_first, 0);
2718	} else {
2719		btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
2720		btrfs_item_key_to_cpu(right, &right_first, 0);
2721	}
2722
2723	if (unlikely(btrfs_comp_cpu_keys(&left_last, &right_first) >= 0)) {
2724		btrfs_crit(left->fs_info, "left extent buffer:");
2725		btrfs_print_tree(left, false);
2726		btrfs_crit(left->fs_info, "right extent buffer:");
2727		btrfs_print_tree(right, false);
2728		btrfs_crit(left->fs_info,
2729"bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
2730			   left_last.objectid, left_last.type,
2731			   left_last.offset, right_first.objectid,
2732			   right_first.type, right_first.offset);
2733		return true;
2734	}
2735	return false;
2736}
2737
2738/*
2739 * try to push data from one node into the next node left in the
2740 * tree.
2741 *
2742 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2743 * error, and > 0 if there was no room in the left hand block.
2744 */
2745static int push_node_left(struct btrfs_trans_handle *trans,
 
2746			  struct extent_buffer *dst,
2747			  struct extent_buffer *src, int empty)
2748{
2749	struct btrfs_fs_info *fs_info = trans->fs_info;
2750	int push_items = 0;
2751	int src_nritems;
2752	int dst_nritems;
2753	int ret = 0;
2754
2755	src_nritems = btrfs_header_nritems(src);
2756	dst_nritems = btrfs_header_nritems(dst);
2757	push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2758	WARN_ON(btrfs_header_generation(src) != trans->transid);
2759	WARN_ON(btrfs_header_generation(dst) != trans->transid);
2760
2761	if (!empty && src_nritems <= 8)
2762		return 1;
2763
2764	if (push_items <= 0)
2765		return 1;
2766
2767	if (empty) {
2768		push_items = min(src_nritems, push_items);
2769		if (push_items < src_nritems) {
2770			/* leave at least 8 pointers in the node if
2771			 * we aren't going to empty it
2772			 */
2773			if (src_nritems - push_items < 8) {
2774				if (push_items <= 8)
2775					return 1;
2776				push_items -= 8;
2777			}
2778		}
2779	} else
2780		push_items = min(src_nritems - 8, push_items);
2781
2782	/* dst is the left eb, src is the middle eb */
2783	if (check_sibling_keys(dst, src)) {
2784		ret = -EUCLEAN;
2785		btrfs_abort_transaction(trans, ret);
2786		return ret;
2787	}
2788	ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
2789	if (ret) {
2790		btrfs_abort_transaction(trans, ret);
2791		return ret;
2792	}
2793	copy_extent_buffer(dst, src,
2794			   btrfs_node_key_ptr_offset(dst, dst_nritems),
2795			   btrfs_node_key_ptr_offset(src, 0),
2796			   push_items * sizeof(struct btrfs_key_ptr));
2797
2798	if (push_items < src_nritems) {
2799		/*
2800		 * btrfs_tree_mod_log_eb_copy handles logging the move, so we
2801		 * don't need to do an explicit tree mod log operation for it.
2802		 */
2803		memmove_extent_buffer(src, btrfs_node_key_ptr_offset(src, 0),
2804				      btrfs_node_key_ptr_offset(src, push_items),
2805				      (src_nritems - push_items) *
2806				      sizeof(struct btrfs_key_ptr));
2807	}
2808	btrfs_set_header_nritems(src, src_nritems - push_items);
2809	btrfs_set_header_nritems(dst, dst_nritems + push_items);
2810	btrfs_mark_buffer_dirty(trans, src);
2811	btrfs_mark_buffer_dirty(trans, dst);
2812
2813	return ret;
2814}
2815
2816/*
2817 * try to push data from one node into the next node right in the
2818 * tree.
2819 *
2820 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2821 * error, and > 0 if there was no room in the right hand block.
2822 *
2823 * this will  only push up to 1/2 the contents of the left node over
2824 */
2825static int balance_node_right(struct btrfs_trans_handle *trans,
 
2826			      struct extent_buffer *dst,
2827			      struct extent_buffer *src)
2828{
2829	struct btrfs_fs_info *fs_info = trans->fs_info;
2830	int push_items = 0;
2831	int max_push;
2832	int src_nritems;
2833	int dst_nritems;
2834	int ret = 0;
2835
2836	WARN_ON(btrfs_header_generation(src) != trans->transid);
2837	WARN_ON(btrfs_header_generation(dst) != trans->transid);
2838
2839	src_nritems = btrfs_header_nritems(src);
2840	dst_nritems = btrfs_header_nritems(dst);
2841	push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2842	if (push_items <= 0)
2843		return 1;
2844
2845	if (src_nritems < 4)
2846		return 1;
2847
2848	max_push = src_nritems / 2 + 1;
2849	/* don't try to empty the node */
2850	if (max_push >= src_nritems)
2851		return 1;
2852
2853	if (max_push < push_items)
2854		push_items = max_push;
2855
2856	/* dst is the right eb, src is the middle eb */
2857	if (check_sibling_keys(src, dst)) {
2858		ret = -EUCLEAN;
2859		btrfs_abort_transaction(trans, ret);
2860		return ret;
2861	}
2862
2863	/*
2864	 * btrfs_tree_mod_log_eb_copy handles logging the move, so we don't
2865	 * need to do an explicit tree mod log operation for it.
2866	 */
2867	memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(dst, push_items),
2868				      btrfs_node_key_ptr_offset(dst, 0),
2869				      (dst_nritems) *
2870				      sizeof(struct btrfs_key_ptr));
2871
2872	ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
2873					 push_items);
2874	if (ret) {
2875		btrfs_abort_transaction(trans, ret);
2876		return ret;
2877	}
2878	copy_extent_buffer(dst, src,
2879			   btrfs_node_key_ptr_offset(dst, 0),
2880			   btrfs_node_key_ptr_offset(src, src_nritems - push_items),
2881			   push_items * sizeof(struct btrfs_key_ptr));
2882
2883	btrfs_set_header_nritems(src, src_nritems - push_items);
2884	btrfs_set_header_nritems(dst, dst_nritems + push_items);
2885
2886	btrfs_mark_buffer_dirty(trans, src);
2887	btrfs_mark_buffer_dirty(trans, dst);
2888
2889	return ret;
2890}
2891
2892/*
2893 * helper function to insert a new root level in the tree.
2894 * A new node is allocated, and a single item is inserted to
2895 * point to the existing root
2896 *
2897 * returns zero on success or < 0 on failure.
2898 */
2899static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2900			   struct btrfs_root *root,
2901			   struct btrfs_path *path, int level)
2902{
 
2903	u64 lower_gen;
2904	struct extent_buffer *lower;
2905	struct extent_buffer *c;
2906	struct extent_buffer *old;
2907	struct btrfs_disk_key lower_key;
2908	int ret;
2909
2910	BUG_ON(path->nodes[level]);
2911	BUG_ON(path->nodes[level-1] != root->node);
2912
2913	lower = path->nodes[level-1];
2914	if (level == 1)
2915		btrfs_item_key(lower, &lower_key, 0);
2916	else
2917		btrfs_node_key(lower, &lower_key, 0);
2918
2919	c = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
2920				   &lower_key, level, root->node->start, 0,
2921				   0, BTRFS_NESTING_NEW_ROOT);
2922	if (IS_ERR(c))
2923		return PTR_ERR(c);
2924
2925	root_add_used_bytes(root);
2926
 
2927	btrfs_set_header_nritems(c, 1);
 
 
 
 
 
 
 
 
 
2928	btrfs_set_node_key(c, &lower_key, 0);
2929	btrfs_set_node_blockptr(c, 0, lower->start);
2930	lower_gen = btrfs_header_generation(lower);
2931	WARN_ON(lower_gen != trans->transid);
2932
2933	btrfs_set_node_ptr_generation(c, 0, lower_gen);
2934
2935	btrfs_mark_buffer_dirty(trans, c);
2936
2937	old = root->node;
2938	ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
2939	if (ret < 0) {
2940		int ret2;
2941
2942		ret2 = btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
2943		if (ret2 < 0)
2944			btrfs_abort_transaction(trans, ret2);
2945		btrfs_tree_unlock(c);
2946		free_extent_buffer(c);
2947		return ret;
2948	}
2949	rcu_assign_pointer(root->node, c);
2950
2951	/* the super has an extra ref to root->node */
2952	free_extent_buffer(old);
2953
2954	add_root_to_dirty_list(root);
2955	atomic_inc(&c->refs);
2956	path->nodes[level] = c;
2957	path->locks[level] = BTRFS_WRITE_LOCK;
2958	path->slots[level] = 0;
2959	return 0;
2960}
2961
2962/*
2963 * worker function to insert a single pointer in a node.
2964 * the node should have enough room for the pointer already
2965 *
2966 * slot and level indicate where you want the key to go, and
2967 * blocknr is the block the key points to.
2968 */
2969static int insert_ptr(struct btrfs_trans_handle *trans,
2970		      const struct btrfs_path *path,
2971		      const struct btrfs_disk_key *key, u64 bytenr,
2972		      int slot, int level)
2973{
2974	struct extent_buffer *lower;
2975	int nritems;
2976	int ret;
2977
2978	BUG_ON(!path->nodes[level]);
2979	btrfs_assert_tree_write_locked(path->nodes[level]);
2980	lower = path->nodes[level];
2981	nritems = btrfs_header_nritems(lower);
2982	BUG_ON(slot > nritems);
2983	BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
2984	if (slot != nritems) {
2985		if (level) {
2986			ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
2987					slot, nritems - slot);
2988			if (ret < 0) {
2989				btrfs_abort_transaction(trans, ret);
2990				return ret;
2991			}
2992		}
2993		memmove_extent_buffer(lower,
2994			      btrfs_node_key_ptr_offset(lower, slot + 1),
2995			      btrfs_node_key_ptr_offset(lower, slot),
2996			      (nritems - slot) * sizeof(struct btrfs_key_ptr));
2997	}
2998	if (level) {
2999		ret = btrfs_tree_mod_log_insert_key(lower, slot,
3000						    BTRFS_MOD_LOG_KEY_ADD);
3001		if (ret < 0) {
3002			btrfs_abort_transaction(trans, ret);
3003			return ret;
3004		}
3005	}
3006	btrfs_set_node_key(lower, key, slot);
3007	btrfs_set_node_blockptr(lower, slot, bytenr);
3008	WARN_ON(trans->transid == 0);
3009	btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3010	btrfs_set_header_nritems(lower, nritems + 1);
3011	btrfs_mark_buffer_dirty(trans, lower);
3012
3013	return 0;
3014}
3015
3016/*
3017 * split the node at the specified level in path in two.
3018 * The path is corrected to point to the appropriate node after the split
3019 *
3020 * Before splitting this tries to make some room in the node by pushing
3021 * left and right, if either one works, it returns right away.
3022 *
3023 * returns 0 on success and < 0 on failure
3024 */
3025static noinline int split_node(struct btrfs_trans_handle *trans,
3026			       struct btrfs_root *root,
3027			       struct btrfs_path *path, int level)
3028{
3029	struct btrfs_fs_info *fs_info = root->fs_info;
3030	struct extent_buffer *c;
3031	struct extent_buffer *split;
3032	struct btrfs_disk_key disk_key;
3033	int mid;
3034	int ret;
3035	u32 c_nritems;
3036
3037	c = path->nodes[level];
3038	WARN_ON(btrfs_header_generation(c) != trans->transid);
3039	if (c == root->node) {
3040		/*
3041		 * trying to split the root, lets make a new one
3042		 *
3043		 * tree mod log: We don't log_removal old root in
3044		 * insert_new_root, because that root buffer will be kept as a
3045		 * normal node. We are going to log removal of half of the
3046		 * elements below with btrfs_tree_mod_log_eb_copy(). We're
3047		 * holding a tree lock on the buffer, which is why we cannot
3048		 * race with other tree_mod_log users.
3049		 */
3050		ret = insert_new_root(trans, root, path, level + 1);
3051		if (ret)
3052			return ret;
3053	} else {
3054		ret = push_nodes_for_insert(trans, root, path, level);
3055		c = path->nodes[level];
3056		if (!ret && btrfs_header_nritems(c) <
3057		    BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3058			return 0;
3059		if (ret < 0)
3060			return ret;
3061	}
3062
3063	c_nritems = btrfs_header_nritems(c);
3064	mid = (c_nritems + 1) / 2;
3065	btrfs_node_key(c, &disk_key, mid);
3066
3067	split = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
3068				       &disk_key, level, c->start, 0,
3069				       0, BTRFS_NESTING_SPLIT);
3070	if (IS_ERR(split))
3071		return PTR_ERR(split);
3072
3073	root_add_used_bytes(root);
3074	ASSERT(btrfs_header_level(c) == level);
 
 
 
 
 
 
 
 
3075
3076	ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
3077	if (ret) {
3078		btrfs_tree_unlock(split);
3079		free_extent_buffer(split);
3080		btrfs_abort_transaction(trans, ret);
3081		return ret;
3082	}
3083	copy_extent_buffer(split, c,
3084			   btrfs_node_key_ptr_offset(split, 0),
3085			   btrfs_node_key_ptr_offset(c, mid),
3086			   (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3087	btrfs_set_header_nritems(split, c_nritems - mid);
3088	btrfs_set_header_nritems(c, mid);
 
3089
3090	btrfs_mark_buffer_dirty(trans, c);
3091	btrfs_mark_buffer_dirty(trans, split);
3092
3093	ret = insert_ptr(trans, path, &disk_key, split->start,
3094			 path->slots[level + 1] + 1, level + 1);
3095	if (ret < 0) {
3096		btrfs_tree_unlock(split);
3097		free_extent_buffer(split);
3098		return ret;
3099	}
3100
3101	if (path->slots[level] >= mid) {
3102		path->slots[level] -= mid;
3103		btrfs_tree_unlock(c);
3104		free_extent_buffer(c);
3105		path->nodes[level] = split;
3106		path->slots[level + 1] += 1;
3107	} else {
3108		btrfs_tree_unlock(split);
3109		free_extent_buffer(split);
3110	}
3111	return 0;
3112}
3113
3114/*
3115 * how many bytes are required to store the items in a leaf.  start
3116 * and nr indicate which items in the leaf to check.  This totals up the
3117 * space used both by the item structs and the item data
3118 */
3119static int leaf_space_used(const struct extent_buffer *l, int start, int nr)
3120{
 
 
 
3121	int data_len;
3122	int nritems = btrfs_header_nritems(l);
3123	int end = min(nritems, start + nr) - 1;
3124
3125	if (!nr)
3126		return 0;
3127	data_len = btrfs_item_offset(l, start) + btrfs_item_size(l, start);
3128	data_len = data_len - btrfs_item_offset(l, end);
 
 
 
 
3129	data_len += sizeof(struct btrfs_item) * nr;
3130	WARN_ON(data_len < 0);
3131	return data_len;
3132}
3133
3134/*
3135 * The space between the end of the leaf items and
3136 * the start of the leaf data.  IOW, how much room
3137 * the leaf has left for both items and data
3138 */
3139int btrfs_leaf_free_space(const struct extent_buffer *leaf)
 
3140{
3141	struct btrfs_fs_info *fs_info = leaf->fs_info;
3142	int nritems = btrfs_header_nritems(leaf);
3143	int ret;
3144
3145	ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3146	if (ret < 0) {
3147		btrfs_crit(fs_info,
3148			   "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3149			   ret,
3150			   (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3151			   leaf_space_used(leaf, 0, nritems), nritems);
3152	}
3153	return ret;
3154}
3155
3156/*
3157 * min slot controls the lowest index we're willing to push to the
3158 * right.  We'll push up to and including min_slot, but no lower
3159 */
3160static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3161				      struct btrfs_path *path,
3162				      int data_size, int empty,
3163				      struct extent_buffer *right,
3164				      int free_space, u32 left_nritems,
3165				      u32 min_slot)
3166{
3167	struct btrfs_fs_info *fs_info = right->fs_info;
3168	struct extent_buffer *left = path->nodes[0];
3169	struct extent_buffer *upper = path->nodes[1];
3170	struct btrfs_map_token token;
3171	struct btrfs_disk_key disk_key;
3172	int slot;
3173	u32 i;
3174	int push_space = 0;
3175	int push_items = 0;
 
3176	u32 nr;
3177	u32 right_nritems;
3178	u32 data_end;
3179	u32 this_item_size;
3180
 
 
3181	if (empty)
3182		nr = 0;
3183	else
3184		nr = max_t(u32, 1, min_slot);
3185
3186	if (path->slots[0] >= left_nritems)
3187		push_space += data_size;
3188
3189	slot = path->slots[1];
3190	i = left_nritems - 1;
3191	while (i >= nr) {
 
 
3192		if (!empty && push_items > 0) {
3193			if (path->slots[0] > i)
3194				break;
3195			if (path->slots[0] == i) {
3196				int space = btrfs_leaf_free_space(left);
3197
3198				if (space + push_space * 2 > free_space)
3199					break;
3200			}
3201		}
3202
3203		if (path->slots[0] == i)
3204			push_space += data_size;
3205
3206		this_item_size = btrfs_item_size(left, i);
3207		if (this_item_size + sizeof(struct btrfs_item) +
3208		    push_space > free_space)
3209			break;
3210
3211		push_items++;
3212		push_space += this_item_size + sizeof(struct btrfs_item);
3213		if (i == 0)
3214			break;
3215		i--;
3216	}
3217
3218	if (push_items == 0)
3219		goto out_unlock;
3220
3221	WARN_ON(!empty && push_items == left_nritems);
3222
3223	/* push left to right */
3224	right_nritems = btrfs_header_nritems(right);
3225
3226	push_space = btrfs_item_data_end(left, left_nritems - push_items);
3227	push_space -= leaf_data_end(left);
3228
3229	/* make room in the right data area */
3230	data_end = leaf_data_end(right);
3231	memmove_leaf_data(right, data_end - push_space, data_end,
3232			  BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
 
 
3233
3234	/* copy from the left data area */
3235	copy_leaf_data(right, left, BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3236		       leaf_data_end(left), push_space);
3237
3238	memmove_leaf_items(right, push_items, 0, right_nritems);
 
 
 
 
3239
3240	/* copy the items from left to right */
3241	copy_leaf_items(right, left, 0, left_nritems - push_items, push_items);
 
 
3242
3243	/* update the item pointers */
3244	btrfs_init_map_token(&token, right);
3245	right_nritems += push_items;
3246	btrfs_set_header_nritems(right, right_nritems);
3247	push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3248	for (i = 0; i < right_nritems; i++) {
3249		push_space -= btrfs_token_item_size(&token, i);
3250		btrfs_set_token_item_offset(&token, i, push_space);
 
3251	}
3252
3253	left_nritems -= push_items;
3254	btrfs_set_header_nritems(left, left_nritems);
3255
3256	if (left_nritems)
3257		btrfs_mark_buffer_dirty(trans, left);
3258	else
3259		btrfs_clear_buffer_dirty(trans, left);
3260
3261	btrfs_mark_buffer_dirty(trans, right);
3262
3263	btrfs_item_key(right, &disk_key, 0);
3264	btrfs_set_node_key(upper, &disk_key, slot + 1);
3265	btrfs_mark_buffer_dirty(trans, upper);
3266
3267	/* then fixup the leaf pointer in the path */
3268	if (path->slots[0] >= left_nritems) {
3269		path->slots[0] -= left_nritems;
3270		if (btrfs_header_nritems(path->nodes[0]) == 0)
3271			btrfs_clear_buffer_dirty(trans, path->nodes[0]);
3272		btrfs_tree_unlock(path->nodes[0]);
3273		free_extent_buffer(path->nodes[0]);
3274		path->nodes[0] = right;
3275		path->slots[1] += 1;
3276	} else {
3277		btrfs_tree_unlock(right);
3278		free_extent_buffer(right);
3279	}
3280	return 0;
3281
3282out_unlock:
3283	btrfs_tree_unlock(right);
3284	free_extent_buffer(right);
3285	return 1;
3286}
3287
3288/*
3289 * push some data in the path leaf to the right, trying to free up at
3290 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3291 *
3292 * returns 1 if the push failed because the other node didn't have enough
3293 * room, 0 if everything worked out and < 0 if there were major errors.
3294 *
3295 * this will push starting from min_slot to the end of the leaf.  It won't
3296 * push any slot lower than min_slot
3297 */
3298static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3299			   *root, struct btrfs_path *path,
3300			   int min_data_size, int data_size,
3301			   int empty, u32 min_slot)
3302{
 
3303	struct extent_buffer *left = path->nodes[0];
3304	struct extent_buffer *right;
3305	struct extent_buffer *upper;
3306	int slot;
3307	int free_space;
3308	u32 left_nritems;
3309	int ret;
3310
3311	if (!path->nodes[1])
3312		return 1;
3313
3314	slot = path->slots[1];
3315	upper = path->nodes[1];
3316	if (slot >= btrfs_header_nritems(upper) - 1)
3317		return 1;
3318
3319	btrfs_assert_tree_write_locked(path->nodes[1]);
3320
3321	right = btrfs_read_node_slot(upper, slot + 1);
 
 
 
 
3322	if (IS_ERR(right))
3323		return PTR_ERR(right);
3324
3325	btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
 
3326
3327	free_space = btrfs_leaf_free_space(right);
3328	if (free_space < data_size)
3329		goto out_unlock;
3330
 
3331	ret = btrfs_cow_block(trans, root, right, upper,
3332			      slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
3333	if (ret)
3334		goto out_unlock;
3335
 
 
 
 
3336	left_nritems = btrfs_header_nritems(left);
3337	if (left_nritems == 0)
3338		goto out_unlock;
3339
3340	if (check_sibling_keys(left, right)) {
3341		ret = -EUCLEAN;
3342		btrfs_abort_transaction(trans, ret);
3343		btrfs_tree_unlock(right);
3344		free_extent_buffer(right);
3345		return ret;
3346	}
3347	if (path->slots[0] == left_nritems && !empty) {
3348		/* Key greater than all keys in the leaf, right neighbor has
3349		 * enough room for it and we're not emptying our leaf to delete
3350		 * it, therefore use right neighbor to insert the new item and
3351		 * no need to touch/dirty our left leaf. */
3352		btrfs_tree_unlock(left);
3353		free_extent_buffer(left);
3354		path->nodes[0] = right;
3355		path->slots[0] = 0;
3356		path->slots[1]++;
3357		return 0;
3358	}
3359
3360	return __push_leaf_right(trans, path, min_data_size, empty, right,
3361				 free_space, left_nritems, min_slot);
3362out_unlock:
3363	btrfs_tree_unlock(right);
3364	free_extent_buffer(right);
3365	return 1;
3366}
3367
3368/*
3369 * push some data in the path leaf to the left, trying to free up at
3370 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3371 *
3372 * max_slot can put a limit on how far into the leaf we'll push items.  The
3373 * item at 'max_slot' won't be touched.  Use (u32)-1 to make us do all the
3374 * items
3375 */
3376static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3377				     struct btrfs_path *path, int data_size,
3378				     int empty, struct extent_buffer *left,
3379				     int free_space, u32 right_nritems,
3380				     u32 max_slot)
3381{
3382	struct btrfs_fs_info *fs_info = left->fs_info;
3383	struct btrfs_disk_key disk_key;
3384	struct extent_buffer *right = path->nodes[0];
3385	int i;
3386	int push_space = 0;
3387	int push_items = 0;
 
3388	u32 old_left_nritems;
3389	u32 nr;
3390	int ret = 0;
3391	u32 this_item_size;
3392	u32 old_left_item_size;
3393	struct btrfs_map_token token;
3394
 
 
3395	if (empty)
3396		nr = min(right_nritems, max_slot);
3397	else
3398		nr = min(right_nritems - 1, max_slot);
3399
3400	for (i = 0; i < nr; i++) {
 
 
3401		if (!empty && push_items > 0) {
3402			if (path->slots[0] < i)
3403				break;
3404			if (path->slots[0] == i) {
3405				int space = btrfs_leaf_free_space(right);
3406
3407				if (space + push_space * 2 > free_space)
3408					break;
3409			}
3410		}
3411
3412		if (path->slots[0] == i)
3413			push_space += data_size;
3414
3415		this_item_size = btrfs_item_size(right, i);
3416		if (this_item_size + sizeof(struct btrfs_item) + push_space >
3417		    free_space)
3418			break;
3419
3420		push_items++;
3421		push_space += this_item_size + sizeof(struct btrfs_item);
3422	}
3423
3424	if (push_items == 0) {
3425		ret = 1;
3426		goto out;
3427	}
3428	WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3429
3430	/* push data from right to left */
3431	copy_leaf_items(left, right, btrfs_header_nritems(left), 0, push_items);
 
 
 
3432
3433	push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3434		     btrfs_item_offset(right, push_items - 1);
3435
3436	copy_leaf_data(left, right, leaf_data_end(left) - push_space,
3437		       btrfs_item_offset(right, push_items - 1), push_space);
 
 
 
3438	old_left_nritems = btrfs_header_nritems(left);
3439	BUG_ON(old_left_nritems <= 0);
3440
3441	btrfs_init_map_token(&token, left);
3442	old_left_item_size = btrfs_item_offset(left, old_left_nritems - 1);
3443	for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3444		u32 ioff;
3445
3446		ioff = btrfs_token_item_offset(&token, i);
3447		btrfs_set_token_item_offset(&token, i,
3448		      ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
 
 
 
3449	}
3450	btrfs_set_header_nritems(left, old_left_nritems + push_items);
3451
3452	/* fixup right node */
3453	if (push_items > right_nritems)
3454		WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3455		       right_nritems);
3456
3457	if (push_items < right_nritems) {
3458		push_space = btrfs_item_offset(right, push_items - 1) -
3459						  leaf_data_end(right);
3460		memmove_leaf_data(right,
3461				  BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3462				  leaf_data_end(right), push_space);
3463
3464		memmove_leaf_items(right, 0, push_items,
3465				   btrfs_header_nritems(right) - push_items);
 
 
 
3466	}
3467
3468	btrfs_init_map_token(&token, right);
3469	right_nritems -= push_items;
3470	btrfs_set_header_nritems(right, right_nritems);
3471	push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3472	for (i = 0; i < right_nritems; i++) {
3473		push_space = push_space - btrfs_token_item_size(&token, i);
3474		btrfs_set_token_item_offset(&token, i, push_space);
 
 
 
3475	}
3476
3477	btrfs_mark_buffer_dirty(trans, left);
3478	if (right_nritems)
3479		btrfs_mark_buffer_dirty(trans, right);
3480	else
3481		btrfs_clear_buffer_dirty(trans, right);
3482
3483	btrfs_item_key(right, &disk_key, 0);
3484	fixup_low_keys(trans, path, &disk_key, 1);
3485
3486	/* then fixup the leaf pointer in the path */
3487	if (path->slots[0] < push_items) {
3488		path->slots[0] += old_left_nritems;
3489		btrfs_tree_unlock(path->nodes[0]);
3490		free_extent_buffer(path->nodes[0]);
3491		path->nodes[0] = left;
3492		path->slots[1] -= 1;
3493	} else {
3494		btrfs_tree_unlock(left);
3495		free_extent_buffer(left);
3496		path->slots[0] -= push_items;
3497	}
3498	BUG_ON(path->slots[0] < 0);
3499	return ret;
3500out:
3501	btrfs_tree_unlock(left);
3502	free_extent_buffer(left);
3503	return ret;
3504}
3505
3506/*
3507 * push some data in the path leaf to the left, trying to free up at
3508 * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3509 *
3510 * max_slot can put a limit on how far into the leaf we'll push items.  The
3511 * item at 'max_slot' won't be touched.  Use (u32)-1 to make us push all the
3512 * items
3513 */
3514static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3515			  *root, struct btrfs_path *path, int min_data_size,
3516			  int data_size, int empty, u32 max_slot)
3517{
 
3518	struct extent_buffer *right = path->nodes[0];
3519	struct extent_buffer *left;
3520	int slot;
3521	int free_space;
3522	u32 right_nritems;
3523	int ret = 0;
3524
3525	slot = path->slots[1];
3526	if (slot == 0)
3527		return 1;
3528	if (!path->nodes[1])
3529		return 1;
3530
3531	right_nritems = btrfs_header_nritems(right);
3532	if (right_nritems == 0)
3533		return 1;
3534
3535	btrfs_assert_tree_write_locked(path->nodes[1]);
3536
3537	left = btrfs_read_node_slot(path->nodes[1], slot - 1);
 
 
 
 
3538	if (IS_ERR(left))
3539		return PTR_ERR(left);
3540
3541	btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
 
3542
3543	free_space = btrfs_leaf_free_space(left);
3544	if (free_space < data_size) {
3545		ret = 1;
3546		goto out;
3547	}
3548
 
3549	ret = btrfs_cow_block(trans, root, left,
3550			      path->nodes[1], slot - 1, &left,
3551			      BTRFS_NESTING_LEFT_COW);
3552	if (ret) {
3553		/* we hit -ENOSPC, but it isn't fatal here */
3554		if (ret == -ENOSPC)
3555			ret = 1;
3556		goto out;
3557	}
3558
3559	if (check_sibling_keys(left, right)) {
3560		ret = -EUCLEAN;
3561		btrfs_abort_transaction(trans, ret);
3562		goto out;
3563	}
3564	return __push_leaf_left(trans, path, min_data_size, empty, left,
3565				free_space, right_nritems, max_slot);
 
 
3566out:
3567	btrfs_tree_unlock(left);
3568	free_extent_buffer(left);
3569	return ret;
3570}
3571
3572/*
3573 * split the path's leaf in two, making sure there is at least data_size
3574 * available for the resulting leaf level of the path.
3575 */
3576static noinline int copy_for_split(struct btrfs_trans_handle *trans,
3577				   struct btrfs_path *path,
3578				   struct extent_buffer *l,
3579				   struct extent_buffer *right,
3580				   int slot, int mid, int nritems)
 
3581{
3582	struct btrfs_fs_info *fs_info = trans->fs_info;
3583	int data_copy_size;
3584	int rt_data_off;
3585	int i;
3586	int ret;
3587	struct btrfs_disk_key disk_key;
3588	struct btrfs_map_token token;
3589
 
 
3590	nritems = nritems - mid;
3591	btrfs_set_header_nritems(right, nritems);
3592	data_copy_size = btrfs_item_data_end(l, mid) - leaf_data_end(l);
3593
3594	copy_leaf_items(right, l, 0, mid, nritems);
3595
3596	copy_leaf_data(right, l, BTRFS_LEAF_DATA_SIZE(fs_info) - data_copy_size,
3597		       leaf_data_end(l), data_copy_size);
 
 
 
 
 
 
3598
3599	rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_data_end(l, mid);
3600
3601	btrfs_init_map_token(&token, right);
3602	for (i = 0; i < nritems; i++) {
 
3603		u32 ioff;
3604
3605		ioff = btrfs_token_item_offset(&token, i);
3606		btrfs_set_token_item_offset(&token, i, ioff + rt_data_off);
 
3607	}
3608
3609	btrfs_set_header_nritems(l, mid);
3610	btrfs_item_key(right, &disk_key, 0);
3611	ret = insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
3612	if (ret < 0)
3613		return ret;
3614
3615	btrfs_mark_buffer_dirty(trans, right);
3616	btrfs_mark_buffer_dirty(trans, l);
3617	BUG_ON(path->slots[0] != slot);
3618
3619	if (mid <= slot) {
3620		btrfs_tree_unlock(path->nodes[0]);
3621		free_extent_buffer(path->nodes[0]);
3622		path->nodes[0] = right;
3623		path->slots[0] -= mid;
3624		path->slots[1] += 1;
3625	} else {
3626		btrfs_tree_unlock(right);
3627		free_extent_buffer(right);
3628	}
3629
3630	BUG_ON(path->slots[0] < 0);
3631
3632	return 0;
3633}
3634
3635/*
3636 * double splits happen when we need to insert a big item in the middle
3637 * of a leaf.  A double split can leave us with 3 mostly empty leaves:
3638 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3639 *          A                 B                 C
3640 *
3641 * We avoid this by trying to push the items on either side of our target
3642 * into the adjacent leaves.  If all goes well we can avoid the double split
3643 * completely.
3644 */
3645static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3646					  struct btrfs_root *root,
3647					  struct btrfs_path *path,
3648					  int data_size)
3649{
 
3650	int ret;
3651	int progress = 0;
3652	int slot;
3653	u32 nritems;
3654	int space_needed = data_size;
3655
3656	slot = path->slots[0];
3657	if (slot < btrfs_header_nritems(path->nodes[0]))
3658		space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3659
3660	/*
3661	 * try to push all the items after our slot into the
3662	 * right leaf
3663	 */
3664	ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
3665	if (ret < 0)
3666		return ret;
3667
3668	if (ret == 0)
3669		progress++;
3670
3671	nritems = btrfs_header_nritems(path->nodes[0]);
3672	/*
3673	 * our goal is to get our slot at the start or end of a leaf.  If
3674	 * we've done so we're done
3675	 */
3676	if (path->slots[0] == 0 || path->slots[0] == nritems)
3677		return 0;
3678
3679	if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3680		return 0;
3681
3682	/* try to push all the items before our slot into the next leaf */
3683	slot = path->slots[0];
3684	space_needed = data_size;
3685	if (slot > 0)
3686		space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3687	ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
3688	if (ret < 0)
3689		return ret;
3690
3691	if (ret == 0)
3692		progress++;
3693
3694	if (progress)
3695		return 0;
3696	return 1;
3697}
3698
3699/*
3700 * split the path's leaf in two, making sure there is at least data_size
3701 * available for the resulting leaf level of the path.
3702 *
3703 * returns 0 if all went well and < 0 on failure.
3704 */
3705static noinline int split_leaf(struct btrfs_trans_handle *trans,
3706			       struct btrfs_root *root,
3707			       const struct btrfs_key *ins_key,
3708			       struct btrfs_path *path, int data_size,
3709			       int extend)
3710{
3711	struct btrfs_disk_key disk_key;
3712	struct extent_buffer *l;
3713	u32 nritems;
3714	int mid;
3715	int slot;
3716	struct extent_buffer *right;
3717	struct btrfs_fs_info *fs_info = root->fs_info;
3718	int ret = 0;
3719	int wret;
3720	int split;
3721	int num_doubles = 0;
3722	int tried_avoid_double = 0;
3723
3724	l = path->nodes[0];
3725	slot = path->slots[0];
3726	if (extend && data_size + btrfs_item_size(l, slot) +
3727	    sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
3728		return -EOVERFLOW;
3729
3730	/* first try to make some room by pushing left and right */
3731	if (data_size && path->nodes[1]) {
3732		int space_needed = data_size;
3733
3734		if (slot < btrfs_header_nritems(l))
3735			space_needed -= btrfs_leaf_free_space(l);
3736
3737		wret = push_leaf_right(trans, root, path, space_needed,
3738				       space_needed, 0, 0);
3739		if (wret < 0)
3740			return wret;
3741		if (wret) {
3742			space_needed = data_size;
3743			if (slot > 0)
3744				space_needed -= btrfs_leaf_free_space(l);
 
3745			wret = push_leaf_left(trans, root, path, space_needed,
3746					      space_needed, 0, (u32)-1);
3747			if (wret < 0)
3748				return wret;
3749		}
3750		l = path->nodes[0];
3751
3752		/* did the pushes work? */
3753		if (btrfs_leaf_free_space(l) >= data_size)
3754			return 0;
3755	}
3756
3757	if (!path->nodes[1]) {
3758		ret = insert_new_root(trans, root, path, 1);
3759		if (ret)
3760			return ret;
3761	}
3762again:
3763	split = 1;
3764	l = path->nodes[0];
3765	slot = path->slots[0];
3766	nritems = btrfs_header_nritems(l);
3767	mid = (nritems + 1) / 2;
3768
3769	if (mid <= slot) {
3770		if (nritems == 1 ||
3771		    leaf_space_used(l, mid, nritems - mid) + data_size >
3772			BTRFS_LEAF_DATA_SIZE(fs_info)) {
3773			if (slot >= nritems) {
3774				split = 0;
3775			} else {
3776				mid = slot;
3777				if (mid != nritems &&
3778				    leaf_space_used(l, mid, nritems - mid) +
3779				    data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3780					if (data_size && !tried_avoid_double)
3781						goto push_for_double;
3782					split = 2;
3783				}
3784			}
3785		}
3786	} else {
3787		if (leaf_space_used(l, 0, mid) + data_size >
3788			BTRFS_LEAF_DATA_SIZE(fs_info)) {
3789			if (!extend && data_size && slot == 0) {
3790				split = 0;
3791			} else if ((extend || !data_size) && slot == 0) {
3792				mid = 1;
3793			} else {
3794				mid = slot;
3795				if (mid != nritems &&
3796				    leaf_space_used(l, mid, nritems - mid) +
3797				    data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3798					if (data_size && !tried_avoid_double)
3799						goto push_for_double;
3800					split = 2;
3801				}
3802			}
3803		}
3804	}
3805
3806	if (split == 0)
3807		btrfs_cpu_key_to_disk(&disk_key, ins_key);
3808	else
3809		btrfs_item_key(l, &disk_key, mid);
3810
3811	/*
3812	 * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
3813	 * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
3814	 * subclasses, which is 8 at the time of this patch, and we've maxed it
3815	 * out.  In the future we could add a
3816	 * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
3817	 * use BTRFS_NESTING_NEW_ROOT.
3818	 */
3819	right = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
3820				       &disk_key, 0, l->start, 0, 0,
3821				       num_doubles ? BTRFS_NESTING_NEW_ROOT :
3822				       BTRFS_NESTING_SPLIT);
3823	if (IS_ERR(right))
3824		return PTR_ERR(right);
3825
3826	root_add_used_bytes(root);
 
 
 
 
 
 
 
 
 
3827
3828	if (split == 0) {
3829		if (mid <= slot) {
3830			btrfs_set_header_nritems(right, 0);
3831			ret = insert_ptr(trans, path, &disk_key,
3832					 right->start, path->slots[1] + 1, 1);
3833			if (ret < 0) {
3834				btrfs_tree_unlock(right);
3835				free_extent_buffer(right);
3836				return ret;
3837			}
3838			btrfs_tree_unlock(path->nodes[0]);
3839			free_extent_buffer(path->nodes[0]);
3840			path->nodes[0] = right;
3841			path->slots[0] = 0;
3842			path->slots[1] += 1;
3843		} else {
3844			btrfs_set_header_nritems(right, 0);
3845			ret = insert_ptr(trans, path, &disk_key,
3846					 right->start, path->slots[1], 1);
3847			if (ret < 0) {
3848				btrfs_tree_unlock(right);
3849				free_extent_buffer(right);
3850				return ret;
3851			}
3852			btrfs_tree_unlock(path->nodes[0]);
3853			free_extent_buffer(path->nodes[0]);
3854			path->nodes[0] = right;
3855			path->slots[0] = 0;
3856			if (path->slots[1] == 0)
3857				fixup_low_keys(trans, path, &disk_key, 1);
3858		}
3859		/*
3860		 * We create a new leaf 'right' for the required ins_len and
3861		 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
3862		 * the content of ins_len to 'right'.
3863		 */
3864		return ret;
3865	}
3866
3867	ret = copy_for_split(trans, path, l, right, slot, mid, nritems);
3868	if (ret < 0) {
3869		btrfs_tree_unlock(right);
3870		free_extent_buffer(right);
3871		return ret;
3872	}
3873
3874	if (split == 2) {
3875		BUG_ON(num_doubles != 0);
3876		num_doubles++;
3877		goto again;
3878	}
3879
3880	return 0;
3881
3882push_for_double:
3883	push_for_double_split(trans, root, path, data_size);
3884	tried_avoid_double = 1;
3885	if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3886		return 0;
3887	goto again;
3888}
3889
3890static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3891					 struct btrfs_root *root,
3892					 struct btrfs_path *path, int ins_len)
3893{
 
3894	struct btrfs_key key;
3895	struct extent_buffer *leaf;
3896	struct btrfs_file_extent_item *fi;
3897	u64 extent_len = 0;
3898	u32 item_size;
3899	int ret;
3900
3901	leaf = path->nodes[0];
3902	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3903
3904	BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3905	       key.type != BTRFS_EXTENT_CSUM_KEY);
3906
3907	if (btrfs_leaf_free_space(leaf) >= ins_len)
3908		return 0;
3909
3910	item_size = btrfs_item_size(leaf, path->slots[0]);
3911	if (key.type == BTRFS_EXTENT_DATA_KEY) {
3912		fi = btrfs_item_ptr(leaf, path->slots[0],
3913				    struct btrfs_file_extent_item);
3914		extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3915	}
3916	btrfs_release_path(path);
3917
3918	path->keep_locks = 1;
3919	path->search_for_split = 1;
3920	ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3921	path->search_for_split = 0;
3922	if (ret > 0)
3923		ret = -EAGAIN;
3924	if (ret < 0)
3925		goto err;
3926
3927	ret = -EAGAIN;
3928	leaf = path->nodes[0];
3929	/* if our item isn't there, return now */
3930	if (item_size != btrfs_item_size(leaf, path->slots[0]))
3931		goto err;
3932
3933	/* the leaf has  changed, it now has room.  return now */
3934	if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
3935		goto err;
3936
3937	if (key.type == BTRFS_EXTENT_DATA_KEY) {
3938		fi = btrfs_item_ptr(leaf, path->slots[0],
3939				    struct btrfs_file_extent_item);
3940		if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3941			goto err;
3942	}
3943
 
3944	ret = split_leaf(trans, root, &key, path, ins_len, 1);
3945	if (ret)
3946		goto err;
3947
3948	path->keep_locks = 0;
3949	btrfs_unlock_up_safe(path, 1);
3950	return 0;
3951err:
3952	path->keep_locks = 0;
3953	return ret;
3954}
3955
3956static noinline int split_item(struct btrfs_trans_handle *trans,
3957			       struct btrfs_path *path,
3958			       const struct btrfs_key *new_key,
3959			       unsigned long split_offset)
3960{
3961	struct extent_buffer *leaf;
3962	int orig_slot, slot;
 
 
3963	char *buf;
3964	u32 nritems;
3965	u32 item_size;
3966	u32 orig_offset;
3967	struct btrfs_disk_key disk_key;
3968
3969	leaf = path->nodes[0];
3970	/*
3971	 * Shouldn't happen because the caller must have previously called
3972	 * setup_leaf_for_split() to make room for the new item in the leaf.
3973	 */
3974	if (WARN_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item)))
3975		return -ENOSPC;
3976
3977	orig_slot = path->slots[0];
3978	orig_offset = btrfs_item_offset(leaf, path->slots[0]);
3979	item_size = btrfs_item_size(leaf, path->slots[0]);
3980
3981	buf = kmalloc(item_size, GFP_NOFS);
3982	if (!buf)
3983		return -ENOMEM;
3984
3985	read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3986			    path->slots[0]), item_size);
3987
3988	slot = path->slots[0] + 1;
3989	nritems = btrfs_header_nritems(leaf);
3990	if (slot != nritems) {
3991		/* shift the items */
3992		memmove_leaf_items(leaf, slot + 1, slot, nritems - slot);
 
 
3993	}
3994
3995	btrfs_cpu_key_to_disk(&disk_key, new_key);
3996	btrfs_set_item_key(leaf, &disk_key, slot);
3997
3998	btrfs_set_item_offset(leaf, slot, orig_offset);
3999	btrfs_set_item_size(leaf, slot, item_size - split_offset);
 
 
4000
4001	btrfs_set_item_offset(leaf, orig_slot,
4002				 orig_offset + item_size - split_offset);
4003	btrfs_set_item_size(leaf, orig_slot, split_offset);
4004
4005	btrfs_set_header_nritems(leaf, nritems + 1);
4006
4007	/* write the data for the start of the original item */
4008	write_extent_buffer(leaf, buf,
4009			    btrfs_item_ptr_offset(leaf, path->slots[0]),
4010			    split_offset);
4011
4012	/* write the data for the new item */
4013	write_extent_buffer(leaf, buf + split_offset,
4014			    btrfs_item_ptr_offset(leaf, slot),
4015			    item_size - split_offset);
4016	btrfs_mark_buffer_dirty(trans, leaf);
4017
4018	BUG_ON(btrfs_leaf_free_space(leaf) < 0);
4019	kfree(buf);
4020	return 0;
4021}
4022
4023/*
4024 * This function splits a single item into two items,
4025 * giving 'new_key' to the new item and splitting the
4026 * old one at split_offset (from the start of the item).
4027 *
4028 * The path may be released by this operation.  After
4029 * the split, the path is pointing to the old item.  The
4030 * new item is going to be in the same node as the old one.
4031 *
4032 * Note, the item being split must be smaller enough to live alone on
4033 * a tree block with room for one extra struct btrfs_item
4034 *
4035 * This allows us to split the item in place, keeping a lock on the
4036 * leaf the entire time.
4037 */
4038int btrfs_split_item(struct btrfs_trans_handle *trans,
4039		     struct btrfs_root *root,
4040		     struct btrfs_path *path,
4041		     const struct btrfs_key *new_key,
4042		     unsigned long split_offset)
4043{
4044	int ret;
4045	ret = setup_leaf_for_split(trans, root, path,
4046				   sizeof(struct btrfs_item));
4047	if (ret)
4048		return ret;
4049
4050	ret = split_item(trans, path, new_key, split_offset);
4051	return ret;
4052}
4053
4054/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4055 * make the item pointed to by the path smaller.  new_size indicates
4056 * how small to make it, and from_end tells us if we just chop bytes
4057 * off the end of the item or if we shift the item to chop bytes off
4058 * the front.
4059 */
4060void btrfs_truncate_item(struct btrfs_trans_handle *trans,
4061			 const struct btrfs_path *path, u32 new_size, int from_end)
4062{
4063	int slot;
4064	struct extent_buffer *leaf;
 
4065	u32 nritems;
4066	unsigned int data_end;
4067	unsigned int old_data_start;
4068	unsigned int old_size;
4069	unsigned int size_diff;
4070	int i;
4071	struct btrfs_map_token token;
4072
 
 
4073	leaf = path->nodes[0];
4074	slot = path->slots[0];
4075
4076	old_size = btrfs_item_size(leaf, slot);
4077	if (old_size == new_size)
4078		return;
4079
4080	nritems = btrfs_header_nritems(leaf);
4081	data_end = leaf_data_end(leaf);
4082
4083	old_data_start = btrfs_item_offset(leaf, slot);
4084
4085	size_diff = old_size - new_size;
4086
4087	BUG_ON(slot < 0);
4088	BUG_ON(slot >= nritems);
4089
4090	/*
4091	 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4092	 */
4093	/* first correct the data pointers */
4094	btrfs_init_map_token(&token, leaf);
4095	for (i = slot; i < nritems; i++) {
4096		u32 ioff;
 
4097
4098		ioff = btrfs_token_item_offset(&token, i);
4099		btrfs_set_token_item_offset(&token, i, ioff + size_diff);
 
4100	}
4101
4102	/* shift the data */
4103	if (from_end) {
4104		memmove_leaf_data(leaf, data_end + size_diff, data_end,
4105				  old_data_start + new_size - data_end);
 
4106	} else {
4107		struct btrfs_disk_key disk_key;
4108		u64 offset;
4109
4110		btrfs_item_key(leaf, &disk_key, slot);
4111
4112		if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4113			unsigned long ptr;
4114			struct btrfs_file_extent_item *fi;
4115
4116			fi = btrfs_item_ptr(leaf, slot,
4117					    struct btrfs_file_extent_item);
4118			fi = (struct btrfs_file_extent_item *)(
4119			     (unsigned long)fi - size_diff);
4120
4121			if (btrfs_file_extent_type(leaf, fi) ==
4122			    BTRFS_FILE_EXTENT_INLINE) {
4123				ptr = btrfs_item_ptr_offset(leaf, slot);
4124				memmove_extent_buffer(leaf, ptr,
4125				      (unsigned long)fi,
4126				      BTRFS_FILE_EXTENT_INLINE_DATA_START);
4127			}
4128		}
4129
4130		memmove_leaf_data(leaf, data_end + size_diff, data_end,
4131				  old_data_start - data_end);
 
4132
4133		offset = btrfs_disk_key_offset(&disk_key);
4134		btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4135		btrfs_set_item_key(leaf, &disk_key, slot);
4136		if (slot == 0)
4137			fixup_low_keys(trans, path, &disk_key, 1);
4138	}
4139
4140	btrfs_set_item_size(leaf, slot, new_size);
4141	btrfs_mark_buffer_dirty(trans, leaf);
 
4142
4143	if (btrfs_leaf_free_space(leaf) < 0) {
4144		btrfs_print_leaf(leaf);
4145		BUG();
4146	}
4147}
4148
4149/*
4150 * make the item pointed to by the path bigger, data_size is the added size.
4151 */
4152void btrfs_extend_item(struct btrfs_trans_handle *trans,
4153		       const struct btrfs_path *path, u32 data_size)
4154{
4155	int slot;
4156	struct extent_buffer *leaf;
 
4157	u32 nritems;
4158	unsigned int data_end;
4159	unsigned int old_data;
4160	unsigned int old_size;
4161	int i;
4162	struct btrfs_map_token token;
4163
 
 
4164	leaf = path->nodes[0];
4165
4166	nritems = btrfs_header_nritems(leaf);
4167	data_end = leaf_data_end(leaf);
4168
4169	if (btrfs_leaf_free_space(leaf) < data_size) {
4170		btrfs_print_leaf(leaf);
4171		BUG();
4172	}
4173	slot = path->slots[0];
4174	old_data = btrfs_item_data_end(leaf, slot);
4175
4176	BUG_ON(slot < 0);
4177	if (slot >= nritems) {
4178		btrfs_print_leaf(leaf);
4179		btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4180			   slot, nritems);
4181		BUG();
4182	}
4183
4184	/*
4185	 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4186	 */
4187	/* first correct the data pointers */
4188	btrfs_init_map_token(&token, leaf);
4189	for (i = slot; i < nritems; i++) {
4190		u32 ioff;
 
4191
4192		ioff = btrfs_token_item_offset(&token, i);
4193		btrfs_set_token_item_offset(&token, i, ioff - data_size);
 
4194	}
4195
4196	/* shift the data */
4197	memmove_leaf_data(leaf, data_end - data_size, data_end,
4198			  old_data - data_end);
 
4199
4200	data_end = old_data;
4201	old_size = btrfs_item_size(leaf, slot);
4202	btrfs_set_item_size(leaf, slot, old_size + data_size);
4203	btrfs_mark_buffer_dirty(trans, leaf);
 
4204
4205	if (btrfs_leaf_free_space(leaf) < 0) {
4206		btrfs_print_leaf(leaf);
4207		BUG();
4208	}
4209}
4210
4211/*
4212 * Make space in the node before inserting one or more items.
4213 *
4214 * @trans:	transaction handle
4215 * @root:	root we are inserting items to
4216 * @path:	points to the leaf/slot where we are going to insert new items
4217 * @batch:      information about the batch of items to insert
4218 *
4219 * Main purpose is to save stack depth by doing the bulk of the work in a
4220 * function that doesn't call btrfs_search_slot
4221 */
4222static void setup_items_for_insert(struct btrfs_trans_handle *trans,
4223				   struct btrfs_root *root, struct btrfs_path *path,
4224				   const struct btrfs_item_batch *batch)
4225{
4226	struct btrfs_fs_info *fs_info = root->fs_info;
 
4227	int i;
4228	u32 nritems;
4229	unsigned int data_end;
4230	struct btrfs_disk_key disk_key;
4231	struct extent_buffer *leaf;
4232	int slot;
4233	struct btrfs_map_token token;
4234	u32 total_size;
4235
4236	/*
4237	 * Before anything else, update keys in the parent and other ancestors
4238	 * if needed, then release the write locks on them, so that other tasks
4239	 * can use them while we modify the leaf.
4240	 */
4241	if (path->slots[0] == 0) {
4242		btrfs_cpu_key_to_disk(&disk_key, &batch->keys[0]);
4243		fixup_low_keys(trans, path, &disk_key, 1);
4244	}
4245	btrfs_unlock_up_safe(path, 1);
4246
 
 
4247	leaf = path->nodes[0];
4248	slot = path->slots[0];
4249
4250	nritems = btrfs_header_nritems(leaf);
4251	data_end = leaf_data_end(leaf);
4252	total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4253
4254	if (btrfs_leaf_free_space(leaf) < total_size) {
4255		btrfs_print_leaf(leaf);
4256		btrfs_crit(fs_info, "not enough freespace need %u have %d",
4257			   total_size, btrfs_leaf_free_space(leaf));
4258		BUG();
4259	}
4260
4261	btrfs_init_map_token(&token, leaf);
4262	if (slot != nritems) {
4263		unsigned int old_data = btrfs_item_data_end(leaf, slot);
4264
4265		if (old_data < data_end) {
4266			btrfs_print_leaf(leaf);
4267			btrfs_crit(fs_info,
4268		"item at slot %d with data offset %u beyond data end of leaf %u",
4269				   slot, old_data, data_end);
4270			BUG();
4271		}
4272		/*
4273		 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4274		 */
4275		/* first correct the data pointers */
4276		for (i = slot; i < nritems; i++) {
4277			u32 ioff;
4278
4279			ioff = btrfs_token_item_offset(&token, i);
4280			btrfs_set_token_item_offset(&token, i,
4281						       ioff - batch->total_data_size);
 
4282		}
4283		/* shift the items */
4284		memmove_leaf_items(leaf, slot + batch->nr, slot, nritems - slot);
 
 
4285
4286		/* shift the data */
4287		memmove_leaf_data(leaf, data_end - batch->total_data_size,
4288				  data_end, old_data - data_end);
 
4289		data_end = old_data;
4290	}
4291
4292	/* setup the item for the new data */
4293	for (i = 0; i < batch->nr; i++) {
4294		btrfs_cpu_key_to_disk(&disk_key, &batch->keys[i]);
4295		btrfs_set_item_key(leaf, &disk_key, slot + i);
4296		data_end -= batch->data_sizes[i];
4297		btrfs_set_token_item_offset(&token, slot + i, data_end);
4298		btrfs_set_token_item_size(&token, slot + i, batch->data_sizes[i]);
 
 
4299	}
4300
4301	btrfs_set_header_nritems(leaf, nritems + batch->nr);
4302	btrfs_mark_buffer_dirty(trans, leaf);
4303
4304	if (btrfs_leaf_free_space(leaf) < 0) {
4305		btrfs_print_leaf(leaf);
4306		BUG();
4307	}
4308}
4309
4310/*
4311 * Insert a new item into a leaf.
4312 *
4313 * @trans:     Transaction handle.
4314 * @root:      The root of the btree.
4315 * @path:      A path pointing to the target leaf and slot.
4316 * @key:       The key of the new item.
4317 * @data_size: The size of the data associated with the new key.
4318 */
4319void btrfs_setup_item_for_insert(struct btrfs_trans_handle *trans,
4320				 struct btrfs_root *root,
4321				 struct btrfs_path *path,
4322				 const struct btrfs_key *key,
4323				 u32 data_size)
4324{
4325	struct btrfs_item_batch batch;
4326
4327	batch.keys = key;
4328	batch.data_sizes = &data_size;
4329	batch.total_data_size = data_size;
4330	batch.nr = 1;
4331
4332	setup_items_for_insert(trans, root, path, &batch);
4333}
4334
4335/*
4336 * Given a key and some data, insert items into the tree.
4337 * This does all the path init required, making room in the tree if needed.
4338 *
4339 * Returns: 0        on success
4340 *          -EEXIST  if the first key already exists
4341 *          < 0      on other errors
4342 */
4343int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4344			    struct btrfs_root *root,
4345			    struct btrfs_path *path,
4346			    const struct btrfs_item_batch *batch)
 
4347{
4348	int ret = 0;
4349	int slot;
4350	u32 total_size;
 
 
 
 
 
4351
4352	total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4353	ret = btrfs_search_slot(trans, root, &batch->keys[0], path, total_size, 1);
4354	if (ret == 0)
4355		return -EEXIST;
4356	if (ret < 0)
4357		return ret;
4358
4359	slot = path->slots[0];
4360	BUG_ON(slot < 0);
4361
4362	setup_items_for_insert(trans, root, path, batch);
 
4363	return 0;
4364}
4365
4366/*
4367 * Given a key and some data, insert an item into the tree.
4368 * This does all the path init required, making room in the tree if needed.
4369 */
4370int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4371		      const struct btrfs_key *cpu_key, void *data,
4372		      u32 data_size)
4373{
4374	int ret = 0;
4375	struct btrfs_path *path;
4376	struct extent_buffer *leaf;
4377	unsigned long ptr;
4378
4379	path = btrfs_alloc_path();
4380	if (!path)
4381		return -ENOMEM;
4382	ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4383	if (!ret) {
4384		leaf = path->nodes[0];
4385		ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4386		write_extent_buffer(leaf, data, ptr, data_size);
4387		btrfs_mark_buffer_dirty(trans, leaf);
4388	}
4389	btrfs_free_path(path);
4390	return ret;
4391}
4392
4393/*
4394 * This function duplicates an item, giving 'new_key' to the new item.
4395 * It guarantees both items live in the same tree leaf and the new item is
4396 * contiguous with the original item.
4397 *
4398 * This allows us to split a file extent in place, keeping a lock on the leaf
4399 * the entire time.
4400 */
4401int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4402			 struct btrfs_root *root,
4403			 struct btrfs_path *path,
4404			 const struct btrfs_key *new_key)
4405{
4406	struct extent_buffer *leaf;
4407	int ret;
4408	u32 item_size;
4409
4410	leaf = path->nodes[0];
4411	item_size = btrfs_item_size(leaf, path->slots[0]);
4412	ret = setup_leaf_for_split(trans, root, path,
4413				   item_size + sizeof(struct btrfs_item));
4414	if (ret)
4415		return ret;
4416
4417	path->slots[0]++;
4418	btrfs_setup_item_for_insert(trans, root, path, new_key, item_size);
4419	leaf = path->nodes[0];
4420	memcpy_extent_buffer(leaf,
4421			     btrfs_item_ptr_offset(leaf, path->slots[0]),
4422			     btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4423			     item_size);
4424	return 0;
4425}
4426
4427/*
4428 * delete the pointer from a given node.
4429 *
4430 * the tree should have been previously balanced so the deletion does not
4431 * empty a node.
4432 *
4433 * This is exported for use inside btrfs-progs, don't un-export it.
4434 */
4435int btrfs_del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4436		  struct btrfs_path *path, int level, int slot)
4437{
 
4438	struct extent_buffer *parent = path->nodes[level];
4439	u32 nritems;
4440	int ret;
4441
4442	nritems = btrfs_header_nritems(parent);
4443	if (slot != nritems - 1) {
4444		if (level) {
4445			ret = btrfs_tree_mod_log_insert_move(parent, slot,
4446					slot + 1, nritems - slot - 1);
4447			if (ret < 0) {
4448				btrfs_abort_transaction(trans, ret);
4449				return ret;
4450			}
4451		}
4452		memmove_extent_buffer(parent,
4453			      btrfs_node_key_ptr_offset(parent, slot),
4454			      btrfs_node_key_ptr_offset(parent, slot + 1),
4455			      sizeof(struct btrfs_key_ptr) *
4456			      (nritems - slot - 1));
4457	} else if (level) {
4458		ret = btrfs_tree_mod_log_insert_key(parent, slot,
4459						    BTRFS_MOD_LOG_KEY_REMOVE);
4460		if (ret < 0) {
4461			btrfs_abort_transaction(trans, ret);
4462			return ret;
4463		}
4464	}
4465
4466	nritems--;
4467	btrfs_set_header_nritems(parent, nritems);
4468	if (nritems == 0 && parent == root->node) {
4469		BUG_ON(btrfs_header_level(root->node) != 1);
4470		/* just turn the root into a leaf and break */
4471		btrfs_set_header_level(root->node, 0);
4472	} else if (slot == 0) {
4473		struct btrfs_disk_key disk_key;
4474
4475		btrfs_node_key(parent, &disk_key, 0);
4476		fixup_low_keys(trans, path, &disk_key, level + 1);
4477	}
4478	btrfs_mark_buffer_dirty(trans, parent);
4479	return 0;
4480}
4481
4482/*
4483 * a helper function to delete the leaf pointed to by path->slots[1] and
4484 * path->nodes[1].
4485 *
4486 * This deletes the pointer in path->nodes[1] and frees the leaf
4487 * block extent.  zero is returned if it all worked out, < 0 otherwise.
4488 *
4489 * The path must have already been setup for deleting the leaf, including
4490 * all the proper balancing.  path->nodes[1] must be locked.
4491 */
4492static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
4493				   struct btrfs_root *root,
4494				   struct btrfs_path *path,
4495				   struct extent_buffer *leaf)
4496{
4497	int ret;
4498
4499	WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4500	ret = btrfs_del_ptr(trans, root, path, 1, path->slots[1]);
4501	if (ret < 0)
4502		return ret;
4503
4504	/*
4505	 * btrfs_free_extent is expensive, we want to make sure we
4506	 * aren't holding any locks when we call it
4507	 */
4508	btrfs_unlock_up_safe(path, 0);
4509
4510	root_sub_used_bytes(root);
4511
4512	atomic_inc(&leaf->refs);
4513	ret = btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
4514	free_extent_buffer_stale(leaf);
4515	if (ret < 0)
4516		btrfs_abort_transaction(trans, ret);
4517
4518	return ret;
4519}
4520/*
4521 * delete the item at the leaf level in path.  If that empties
4522 * the leaf, remove it from the tree
4523 */
4524int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4525		    struct btrfs_path *path, int slot, int nr)
4526{
4527	struct btrfs_fs_info *fs_info = root->fs_info;
4528	struct extent_buffer *leaf;
 
 
 
4529	int ret = 0;
4530	int wret;
 
4531	u32 nritems;
 
 
 
4532
4533	leaf = path->nodes[0];
 
 
 
 
 
4534	nritems = btrfs_header_nritems(leaf);
4535
4536	if (slot + nr != nritems) {
4537		const u32 last_off = btrfs_item_offset(leaf, slot + nr - 1);
4538		const int data_end = leaf_data_end(leaf);
4539		struct btrfs_map_token token;
4540		u32 dsize = 0;
4541		int i;
4542
4543		for (i = 0; i < nr; i++)
4544			dsize += btrfs_item_size(leaf, slot + i);
 
 
4545
4546		memmove_leaf_data(leaf, data_end + dsize, data_end,
4547				  last_off - data_end);
4548
4549		btrfs_init_map_token(&token, leaf);
4550		for (i = slot + nr; i < nritems; i++) {
4551			u32 ioff;
4552
4553			ioff = btrfs_token_item_offset(&token, i);
4554			btrfs_set_token_item_offset(&token, i, ioff + dsize);
 
 
4555		}
4556
4557		memmove_leaf_items(leaf, slot, slot + nr, nritems - slot - nr);
 
 
 
4558	}
4559	btrfs_set_header_nritems(leaf, nritems - nr);
4560	nritems -= nr;
4561
4562	/* delete the leaf if we've emptied it */
4563	if (nritems == 0) {
4564		if (leaf == root->node) {
4565			btrfs_set_header_level(leaf, 0);
4566		} else {
4567			btrfs_clear_buffer_dirty(trans, leaf);
4568			ret = btrfs_del_leaf(trans, root, path, leaf);
4569			if (ret < 0)
4570				return ret;
4571		}
4572	} else {
4573		int used = leaf_space_used(leaf, 0, nritems);
4574		if (slot == 0) {
4575			struct btrfs_disk_key disk_key;
4576
4577			btrfs_item_key(leaf, &disk_key, 0);
4578			fixup_low_keys(trans, path, &disk_key, 1);
4579		}
4580
4581		/*
4582		 * Try to delete the leaf if it is mostly empty. We do this by
4583		 * trying to move all its items into its left and right neighbours.
4584		 * If we can't move all the items, then we don't delete it - it's
4585		 * not ideal, but future insertions might fill the leaf with more
4586		 * items, or items from other leaves might be moved later into our
4587		 * leaf due to deletions on those leaves.
4588		 */
4589		if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4590			u32 min_push_space;
4591
4592			/* push_leaf_left fixes the path.
4593			 * make sure the path still points to our leaf
4594			 * for possible call to btrfs_del_ptr below
4595			 */
4596			slot = path->slots[1];
4597			atomic_inc(&leaf->refs);
4598			/*
4599			 * We want to be able to at least push one item to the
4600			 * left neighbour leaf, and that's the first item.
4601			 */
4602			min_push_space = sizeof(struct btrfs_item) +
4603				btrfs_item_size(leaf, 0);
4604			wret = push_leaf_left(trans, root, path, 0,
4605					      min_push_space, 1, (u32)-1);
4606			if (wret < 0 && wret != -ENOSPC)
4607				ret = wret;
4608
4609			if (path->nodes[0] == leaf &&
4610			    btrfs_header_nritems(leaf)) {
4611				/*
4612				 * If we were not able to push all items from our
4613				 * leaf to its left neighbour, then attempt to
4614				 * either push all the remaining items to the
4615				 * right neighbour or none. There's no advantage
4616				 * in pushing only some items, instead of all, as
4617				 * it's pointless to end up with a leaf having
4618				 * too few items while the neighbours can be full
4619				 * or nearly full.
4620				 */
4621				nritems = btrfs_header_nritems(leaf);
4622				min_push_space = leaf_space_used(leaf, 0, nritems);
4623				wret = push_leaf_right(trans, root, path, 0,
4624						       min_push_space, 1, 0);
4625				if (wret < 0 && wret != -ENOSPC)
4626					ret = wret;
4627			}
4628
4629			if (btrfs_header_nritems(leaf) == 0) {
4630				path->slots[1] = slot;
4631				ret = btrfs_del_leaf(trans, root, path, leaf);
4632				if (ret < 0)
4633					return ret;
4634				free_extent_buffer(leaf);
4635				ret = 0;
4636			} else {
4637				/* if we're still in the path, make sure
4638				 * we're dirty.  Otherwise, one of the
4639				 * push_leaf functions must have already
4640				 * dirtied this buffer
4641				 */
4642				if (path->nodes[0] == leaf)
4643					btrfs_mark_buffer_dirty(trans, leaf);
4644				free_extent_buffer(leaf);
4645			}
4646		} else {
4647			btrfs_mark_buffer_dirty(trans, leaf);
4648		}
4649	}
4650	return ret;
4651}
4652
4653/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4654 * A helper function to walk down the tree starting at min_key, and looking
4655 * for nodes or leaves that are have a minimum transaction id.
4656 * This is used by the btree defrag code, and tree logging
4657 *
4658 * This does not cow, but it does stuff the starting key it finds back
4659 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4660 * key and get a writable path.
4661 *
4662 * This honors path->lowest_level to prevent descent past a given level
4663 * of the tree.
4664 *
4665 * min_trans indicates the oldest transaction that you are interested
4666 * in walking through.  Any nodes or leaves older than min_trans are
4667 * skipped over (without reading them).
4668 *
4669 * returns zero if something useful was found, < 0 on error and 1 if there
4670 * was nothing in the tree that matched the search criteria.
4671 */
4672int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4673			 struct btrfs_path *path,
4674			 u64 min_trans)
4675{
 
4676	struct extent_buffer *cur;
4677	struct btrfs_key found_key;
4678	int slot;
4679	int sret;
4680	u32 nritems;
4681	int level;
4682	int ret = 1;
4683	int keep_locks = path->keep_locks;
4684
4685	ASSERT(!path->nowait);
4686	path->keep_locks = 1;
4687again:
4688	cur = btrfs_read_lock_root_node(root);
4689	level = btrfs_header_level(cur);
4690	WARN_ON(path->nodes[level]);
4691	path->nodes[level] = cur;
4692	path->locks[level] = BTRFS_READ_LOCK;
4693
4694	if (btrfs_header_generation(cur) < min_trans) {
4695		ret = 1;
4696		goto out;
4697	}
4698	while (1) {
4699		nritems = btrfs_header_nritems(cur);
4700		level = btrfs_header_level(cur);
4701		sret = btrfs_bin_search(cur, 0, min_key, &slot);
4702		if (sret < 0) {
4703			ret = sret;
4704			goto out;
4705		}
4706
4707		/* at the lowest level, we're done, setup the path and exit */
4708		if (level == path->lowest_level) {
4709			if (slot >= nritems)
4710				goto find_next_key;
4711			ret = 0;
4712			path->slots[level] = slot;
4713			btrfs_item_key_to_cpu(cur, &found_key, slot);
4714			goto out;
4715		}
4716		if (sret && slot > 0)
4717			slot--;
4718		/*
4719		 * check this node pointer against the min_trans parameters.
4720		 * If it is too old, skip to the next one.
4721		 */
4722		while (slot < nritems) {
4723			u64 gen;
4724
4725			gen = btrfs_node_ptr_generation(cur, slot);
4726			if (gen < min_trans) {
4727				slot++;
4728				continue;
4729			}
4730			break;
4731		}
4732find_next_key:
4733		/*
4734		 * we didn't find a candidate key in this node, walk forward
4735		 * and find another one
4736		 */
4737		if (slot >= nritems) {
4738			path->slots[level] = slot;
 
4739			sret = btrfs_find_next_key(root, path, min_key, level,
4740						  min_trans);
4741			if (sret == 0) {
4742				btrfs_release_path(path);
4743				goto again;
4744			} else {
4745				goto out;
4746			}
4747		}
4748		/* save our key for returning back */
4749		btrfs_node_key_to_cpu(cur, &found_key, slot);
4750		path->slots[level] = slot;
4751		if (level == path->lowest_level) {
4752			ret = 0;
4753			goto out;
4754		}
4755		cur = btrfs_read_node_slot(cur, slot);
 
4756		if (IS_ERR(cur)) {
4757			ret = PTR_ERR(cur);
4758			goto out;
4759		}
4760
4761		btrfs_tree_read_lock(cur);
4762
4763		path->locks[level - 1] = BTRFS_READ_LOCK;
4764		path->nodes[level - 1] = cur;
4765		unlock_up(path, level, 1, 0, NULL);
 
4766	}
4767out:
4768	path->keep_locks = keep_locks;
4769	if (ret == 0) {
4770		btrfs_unlock_up_safe(path, path->lowest_level + 1);
 
4771		memcpy(min_key, &found_key, sizeof(found_key));
4772	}
4773	return ret;
4774}
4775
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4776/*
4777 * this is similar to btrfs_next_leaf, but does not try to preserve
4778 * and fixup the path.  It looks for and returns the next key in the
4779 * tree based on the current path and the min_trans parameters.
4780 *
4781 * 0 is returned if another key is found, < 0 if there are any errors
4782 * and 1 is returned if there are no higher keys in the tree
4783 *
4784 * path->keep_locks should be set to 1 on the search made before
4785 * calling this function.
4786 */
4787int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4788			struct btrfs_key *key, int level, u64 min_trans)
4789{
4790	int slot;
4791	struct extent_buffer *c;
4792
4793	WARN_ON(!path->keep_locks && !path->skip_locking);
4794	while (level < BTRFS_MAX_LEVEL) {
4795		if (!path->nodes[level])
4796			return 1;
4797
4798		slot = path->slots[level] + 1;
4799		c = path->nodes[level];
4800next:
4801		if (slot >= btrfs_header_nritems(c)) {
4802			int ret;
4803			int orig_lowest;
4804			struct btrfs_key cur_key;
4805			if (level + 1 >= BTRFS_MAX_LEVEL ||
4806			    !path->nodes[level + 1])
4807				return 1;
4808
4809			if (path->locks[level + 1] || path->skip_locking) {
4810				level++;
4811				continue;
4812			}
4813
4814			slot = btrfs_header_nritems(c) - 1;
4815			if (level == 0)
4816				btrfs_item_key_to_cpu(c, &cur_key, slot);
4817			else
4818				btrfs_node_key_to_cpu(c, &cur_key, slot);
4819
4820			orig_lowest = path->lowest_level;
4821			btrfs_release_path(path);
4822			path->lowest_level = level;
4823			ret = btrfs_search_slot(NULL, root, &cur_key, path,
4824						0, 0);
4825			path->lowest_level = orig_lowest;
4826			if (ret < 0)
4827				return ret;
4828
4829			c = path->nodes[level];
4830			slot = path->slots[level];
4831			if (ret == 0)
4832				slot++;
4833			goto next;
4834		}
4835
4836		if (level == 0)
4837			btrfs_item_key_to_cpu(c, key, slot);
4838		else {
4839			u64 gen = btrfs_node_ptr_generation(c, slot);
4840
4841			if (gen < min_trans) {
4842				slot++;
4843				goto next;
4844			}
4845			btrfs_node_key_to_cpu(c, key, slot);
4846		}
4847		return 0;
4848	}
4849	return 1;
4850}
4851
 
 
 
 
 
 
 
 
 
 
4852int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
4853			u64 time_seq)
4854{
4855	int slot;
4856	int level;
4857	struct extent_buffer *c;
4858	struct extent_buffer *next;
4859	struct btrfs_fs_info *fs_info = root->fs_info;
4860	struct btrfs_key key;
4861	bool need_commit_sem = false;
4862	u32 nritems;
4863	int ret;
4864	int i;
4865
4866	/*
4867	 * The nowait semantics are used only for write paths, where we don't
4868	 * use the tree mod log and sequence numbers.
4869	 */
4870	if (time_seq)
4871		ASSERT(!path->nowait);
4872
4873	nritems = btrfs_header_nritems(path->nodes[0]);
4874	if (nritems == 0)
4875		return 1;
4876
4877	btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4878again:
4879	level = 1;
4880	next = NULL;
 
4881	btrfs_release_path(path);
4882
4883	path->keep_locks = 1;
 
4884
4885	if (time_seq) {
4886		ret = btrfs_search_old_slot(root, &key, path, time_seq);
4887	} else {
4888		if (path->need_commit_sem) {
4889			path->need_commit_sem = 0;
4890			need_commit_sem = true;
4891			if (path->nowait) {
4892				if (!down_read_trylock(&fs_info->commit_root_sem)) {
4893					ret = -EAGAIN;
4894					goto done;
4895				}
4896			} else {
4897				down_read(&fs_info->commit_root_sem);
4898			}
4899		}
4900		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4901	}
4902	path->keep_locks = 0;
4903
4904	if (ret < 0)
4905		goto done;
4906
4907	nritems = btrfs_header_nritems(path->nodes[0]);
4908	/*
4909	 * by releasing the path above we dropped all our locks.  A balance
4910	 * could have added more items next to the key that used to be
4911	 * at the very end of the block.  So, check again here and
4912	 * advance the path if there are now more items available.
4913	 */
4914	if (nritems > 0 && path->slots[0] < nritems - 1) {
4915		if (ret == 0)
4916			path->slots[0]++;
4917		ret = 0;
4918		goto done;
4919	}
4920	/*
4921	 * So the above check misses one case:
4922	 * - after releasing the path above, someone has removed the item that
4923	 *   used to be at the very end of the block, and balance between leafs
4924	 *   gets another one with bigger key.offset to replace it.
4925	 *
4926	 * This one should be returned as well, or we can get leaf corruption
4927	 * later(esp. in __btrfs_drop_extents()).
4928	 *
4929	 * And a bit more explanation about this check,
4930	 * with ret > 0, the key isn't found, the path points to the slot
4931	 * where it should be inserted, so the path->slots[0] item must be the
4932	 * bigger one.
4933	 */
4934	if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
4935		ret = 0;
4936		goto done;
4937	}
4938
4939	while (level < BTRFS_MAX_LEVEL) {
4940		if (!path->nodes[level]) {
4941			ret = 1;
4942			goto done;
4943		}
4944
4945		slot = path->slots[level] + 1;
4946		c = path->nodes[level];
4947		if (slot >= btrfs_header_nritems(c)) {
4948			level++;
4949			if (level == BTRFS_MAX_LEVEL) {
4950				ret = 1;
4951				goto done;
4952			}
4953			continue;
4954		}
4955
4956
4957		/*
4958		 * Our current level is where we're going to start from, and to
4959		 * make sure lockdep doesn't complain we need to drop our locks
4960		 * and nodes from 0 to our current level.
4961		 */
4962		for (i = 0; i < level; i++) {
4963			if (path->locks[level]) {
4964				btrfs_tree_read_unlock(path->nodes[i]);
4965				path->locks[i] = 0;
4966			}
4967			free_extent_buffer(path->nodes[i]);
4968			path->nodes[i] = NULL;
4969		}
4970
4971		next = c;
4972		ret = read_block_for_search(root, path, &next, slot, &key);
4973		if (ret == -EAGAIN && !path->nowait)
 
 
4974			goto again;
4975
4976		if (ret < 0) {
4977			btrfs_release_path(path);
4978			goto done;
4979		}
4980
4981		if (!path->skip_locking) {
4982			ret = btrfs_try_tree_read_lock(next);
4983			if (!ret && path->nowait) {
4984				ret = -EAGAIN;
4985				goto done;
4986			}
4987			if (!ret && time_seq) {
4988				/*
4989				 * If we don't get the lock, we may be racing
4990				 * with push_leaf_left, holding that lock while
4991				 * itself waiting for the leaf we've currently
4992				 * locked. To solve this situation, we give up
4993				 * on our lock and cycle.
4994				 */
4995				free_extent_buffer(next);
4996				btrfs_release_path(path);
4997				cond_resched();
4998				goto again;
4999			}
5000			if (!ret)
 
5001				btrfs_tree_read_lock(next);
 
 
 
 
5002		}
5003		break;
5004	}
5005	path->slots[level] = slot;
5006	while (1) {
5007		level--;
 
 
 
 
 
5008		path->nodes[level] = next;
5009		path->slots[level] = 0;
5010		if (!path->skip_locking)
5011			path->locks[level] = BTRFS_READ_LOCK;
5012		if (!level)
5013			break;
5014
5015		ret = read_block_for_search(root, path, &next, 0, &key);
5016		if (ret == -EAGAIN && !path->nowait)
 
5017			goto again;
5018
5019		if (ret < 0) {
5020			btrfs_release_path(path);
5021			goto done;
5022		}
5023
5024		if (!path->skip_locking) {
5025			if (path->nowait) {
5026				if (!btrfs_try_tree_read_lock(next)) {
5027					ret = -EAGAIN;
5028					goto done;
5029				}
5030			} else {
5031				btrfs_tree_read_lock(next);
 
 
5032			}
 
5033		}
5034	}
5035	ret = 0;
5036done:
5037	unlock_up(path, 0, 1, 0, NULL);
5038	if (need_commit_sem) {
5039		int ret2;
5040
5041		path->need_commit_sem = 1;
5042		ret2 = finish_need_commit_sem_search(path);
5043		up_read(&fs_info->commit_root_sem);
5044		if (ret2)
5045			ret = ret2;
5046	}
5047
5048	return ret;
5049}
5050
5051int btrfs_next_old_item(struct btrfs_root *root, struct btrfs_path *path, u64 time_seq)
5052{
5053	path->slots[0]++;
5054	if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
5055		return btrfs_next_old_leaf(root, path, time_seq);
5056	return 0;
5057}
5058
5059/*
5060 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5061 * searching until it gets past min_objectid or finds an item of 'type'
5062 *
5063 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5064 */
5065int btrfs_previous_item(struct btrfs_root *root,
5066			struct btrfs_path *path, u64 min_objectid,
5067			int type)
5068{
5069	struct btrfs_key found_key;
5070	struct extent_buffer *leaf;
5071	u32 nritems;
5072	int ret;
5073
5074	while (1) {
5075		if (path->slots[0] == 0) {
 
5076			ret = btrfs_prev_leaf(root, path);
5077			if (ret != 0)
5078				return ret;
5079		} else {
5080			path->slots[0]--;
5081		}
5082		leaf = path->nodes[0];
5083		nritems = btrfs_header_nritems(leaf);
5084		if (nritems == 0)
5085			return 1;
5086		if (path->slots[0] == nritems)
5087			path->slots[0]--;
5088
5089		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5090		if (found_key.objectid < min_objectid)
5091			break;
5092		if (found_key.type == type)
5093			return 0;
5094		if (found_key.objectid == min_objectid &&
5095		    found_key.type < type)
5096			break;
5097	}
5098	return 1;
5099}
5100
5101/*
5102 * search in extent tree to find a previous Metadata/Data extent item with
5103 * min objecitd.
5104 *
5105 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5106 */
5107int btrfs_previous_extent_item(struct btrfs_root *root,
5108			struct btrfs_path *path, u64 min_objectid)
5109{
5110	struct btrfs_key found_key;
5111	struct extent_buffer *leaf;
5112	u32 nritems;
5113	int ret;
5114
5115	while (1) {
5116		if (path->slots[0] == 0) {
 
5117			ret = btrfs_prev_leaf(root, path);
5118			if (ret != 0)
5119				return ret;
5120		} else {
5121			path->slots[0]--;
5122		}
5123		leaf = path->nodes[0];
5124		nritems = btrfs_header_nritems(leaf);
5125		if (nritems == 0)
5126			return 1;
5127		if (path->slots[0] == nritems)
5128			path->slots[0]--;
5129
5130		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5131		if (found_key.objectid < min_objectid)
5132			break;
5133		if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5134		    found_key.type == BTRFS_METADATA_ITEM_KEY)
5135			return 0;
5136		if (found_key.objectid == min_objectid &&
5137		    found_key.type < BTRFS_EXTENT_ITEM_KEY)
5138			break;
5139	}
5140	return 1;
5141}
5142
5143int __init btrfs_ctree_init(void)
5144{
5145	btrfs_path_cachep = KMEM_CACHE(btrfs_path, 0);
5146	if (!btrfs_path_cachep)
5147		return -ENOMEM;
5148	return 0;
5149}
5150
5151void __cold btrfs_ctree_exit(void)
5152{
5153	kmem_cache_destroy(btrfs_path_cachep);
5154}