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