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