1/*
   2 * Copyright (C) 2011 STRATO.  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/vmalloc.h>
  20#include "ctree.h"
  21#include "disk-io.h"
  22#include "backref.h"
  23#include "ulist.h"
  24#include "transaction.h"
  25#include "delayed-ref.h"
  26#include "locking.h"
  27
  28struct extent_inode_elem {
  29	u64 inum;
  30	u64 offset;
  31	struct extent_inode_elem *next;
  32};
  33
  34static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
  35				struct btrfs_file_extent_item *fi,
  36				u64 extent_item_pos,
  37				struct extent_inode_elem **eie)
  38{
  39	u64 offset = 0;
 
  40	struct extent_inode_elem *e;
  41
  42	if (!btrfs_file_extent_compression(eb, fi) &&
  43	    !btrfs_file_extent_encryption(eb, fi) &&
  44	    !btrfs_file_extent_other_encoding(eb, fi)) {
  45		u64 data_offset;
  46		u64 data_len;
  47
  48		data_offset = btrfs_file_extent_offset(eb, fi);
  49		data_len = btrfs_file_extent_num_bytes(eb, fi);
  50
  51		if (extent_item_pos < data_offset ||
  52		    extent_item_pos >= data_offset + data_len)
  53			return 1;
  54		offset = extent_item_pos - data_offset;
  55	}
  56
  57	e = kmalloc(sizeof(*e), GFP_NOFS);
  58	if (!e)
  59		return -ENOMEM;
  60
  61	e->next = *eie;
  62	e->inum = key->objectid;
  63	e->offset = key->offset + offset;
  64	*eie = e;
  65
  66	return 0;
  67}
  68
  69static void free_inode_elem_list(struct extent_inode_elem *eie)
  70{
  71	struct extent_inode_elem *eie_next;
  72
  73	for (; eie; eie = eie_next) {
  74		eie_next = eie->next;
  75		kfree(eie);
  76	}
  77}
  78
  79static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
  80				u64 extent_item_pos,
  81				struct extent_inode_elem **eie)
  82{
  83	u64 disk_byte;
  84	struct btrfs_key key;
  85	struct btrfs_file_extent_item *fi;
  86	int slot;
  87	int nritems;
  88	int extent_type;
  89	int ret;
  90
  91	/*
  92	 * from the shared data ref, we only have the leaf but we need
  93	 * the key. thus, we must look into all items and see that we
  94	 * find one (some) with a reference to our extent item.
  95	 */
  96	nritems = btrfs_header_nritems(eb);
  97	for (slot = 0; slot < nritems; ++slot) {
  98		btrfs_item_key_to_cpu(eb, &key, slot);
  99		if (key.type != BTRFS_EXTENT_DATA_KEY)
 100			continue;
 101		fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
 102		extent_type = btrfs_file_extent_type(eb, fi);
 103		if (extent_type == BTRFS_FILE_EXTENT_INLINE)
 104			continue;
 105		/* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
 106		disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
 107		if (disk_byte != wanted_disk_byte)
 108			continue;
 109
 110		ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
 111		if (ret < 0)
 112			return ret;
 113	}
 114
 115	return 0;
 116}
 117
 118/*
 119 * this structure records all encountered refs on the way up to the root
 120 */
 121struct __prelim_ref {
 122	struct list_head list;
 123	u64 root_id;
 124	struct btrfs_key key_for_search;
 125	int level;
 126	int count;
 127	struct extent_inode_elem *inode_list;
 128	u64 parent;
 129	u64 wanted_disk_byte;
 130};
 131
 132static struct kmem_cache *btrfs_prelim_ref_cache;
 133
 134int __init btrfs_prelim_ref_init(void)
 135{
 136	btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
 137					sizeof(struct __prelim_ref),
 138					0,
 139					SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
 140					NULL);
 141	if (!btrfs_prelim_ref_cache)
 142		return -ENOMEM;
 143	return 0;
 144}
 145
 146void btrfs_prelim_ref_exit(void)
 147{
 148	if (btrfs_prelim_ref_cache)
 149		kmem_cache_destroy(btrfs_prelim_ref_cache);
 150}
 151
 152/*
 153 * the rules for all callers of this function are:
 154 * - obtaining the parent is the goal
 155 * - if you add a key, you must know that it is a correct key
 156 * - if you cannot add the parent or a correct key, then we will look into the
 157 *   block later to set a correct key
 158 *
 159 * delayed refs
 160 * ============
 161 *        backref type | shared | indirect | shared | indirect
 162 * information         |   tree |     tree |   data |     data
 163 * --------------------+--------+----------+--------+----------
 164 *      parent logical |    y   |     -    |    -   |     -
 165 *      key to resolve |    -   |     y    |    y   |     y
 166 *  tree block logical |    -   |     -    |    -   |     -
 167 *  root for resolving |    y   |     y    |    y   |     y
 168 *
 169 * - column 1:       we've the parent -> done
 170 * - column 2, 3, 4: we use the key to find the parent
 171 *
 172 * on disk refs (inline or keyed)
 173 * ==============================
 174 *        backref type | shared | indirect | shared | indirect
 175 * information         |   tree |     tree |   data |     data
 176 * --------------------+--------+----------+--------+----------
 177 *      parent logical |    y   |     -    |    y   |     -
 178 *      key to resolve |    -   |     -    |    -   |     y
 179 *  tree block logical |    y   |     y    |    y   |     y
 180 *  root for resolving |    -   |     y    |    y   |     y
 181 *
 182 * - column 1, 3: we've the parent -> done
 183 * - column 2:    we take the first key from the block to find the parent
 184 *                (see __add_missing_keys)
 185 * - column 4:    we use the key to find the parent
 186 *
 187 * additional information that's available but not required to find the parent
 188 * block might help in merging entries to gain some speed.
 189 */
 190
 191static int __add_prelim_ref(struct list_head *head, u64 root_id,
 192			    struct btrfs_key *key, int level,
 193			    u64 parent, u64 wanted_disk_byte, int count,
 194			    gfp_t gfp_mask)
 195{
 196	struct __prelim_ref *ref;
 197
 198	if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
 199		return 0;
 200
 201	ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
 202	if (!ref)
 203		return -ENOMEM;
 204
 205	ref->root_id = root_id;
 206	if (key)
 207		ref->key_for_search = *key;
 208	else
 209		memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
 210
 211	ref->inode_list = NULL;
 212	ref->level = level;
 213	ref->count = count;
 214	ref->parent = parent;
 215	ref->wanted_disk_byte = wanted_disk_byte;
 216	list_add_tail(&ref->list, head);
 217
 218	return 0;
 219}
 220
 221static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
 222			   struct ulist *parents, struct __prelim_ref *ref,
 223			   int level, u64 time_seq, const u64 *extent_item_pos,
 224			   u64 total_refs)
 
 225{
 226	int ret = 0;
 227	int slot;
 228	struct extent_buffer *eb;
 229	struct btrfs_key key;
 230	struct btrfs_key *key_for_search = &ref->key_for_search;
 231	struct btrfs_file_extent_item *fi;
 232	struct extent_inode_elem *eie = NULL, *old = NULL;
 233	u64 disk_byte;
 234	u64 wanted_disk_byte = ref->wanted_disk_byte;
 235	u64 count = 0;
 236
 237	if (level != 0) {
 238		eb = path->nodes[level];
 239		ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
 240		if (ret < 0)
 241			return ret;
 242		return 0;
 243	}
 244
 245	/*
 246	 * We normally enter this function with the path already pointing to
 247	 * the first item to check. But sometimes, we may enter it with
 248	 * slot==nritems. In that case, go to the next leaf before we continue.
 249	 */
 250	if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
 251		ret = btrfs_next_old_leaf(root, path, time_seq);
 252
 253	while (!ret && count < total_refs) {
 254		eb = path->nodes[0];
 255		slot = path->slots[0];
 256
 257		btrfs_item_key_to_cpu(eb, &key, slot);
 258
 259		if (key.objectid != key_for_search->objectid ||
 260		    key.type != BTRFS_EXTENT_DATA_KEY)
 261			break;
 262
 263		fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
 264		disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
 265
 266		if (disk_byte == wanted_disk_byte) {
 267			eie = NULL;
 268			old = NULL;
 269			count++;
 270			if (extent_item_pos) {
 271				ret = check_extent_in_eb(&key, eb, fi,
 272						*extent_item_pos,
 273						&eie);
 274				if (ret < 0)
 275					break;
 276			}
 277			if (ret > 0)
 278				goto next;
 279			ret = ulist_add_merge(parents, eb->start,
 280					      (uintptr_t)eie,
 281					      (u64 *)&old, GFP_NOFS);
 282			if (ret < 0)
 283				break;
 284			if (!ret && extent_item_pos) {
 285				while (old->next)
 286					old = old->next;
 287				old->next = eie;
 288			}
 289			eie = NULL;
 290		}
 291next:
 292		ret = btrfs_next_old_item(root, path, time_seq);
 293	}
 294
 295	if (ret > 0)
 296		ret = 0;
 297	else if (ret < 0)
 298		free_inode_elem_list(eie);
 299	return ret;
 300}
 301
 302/*
 303 * resolve an indirect backref in the form (root_id, key, level)
 304 * to a logical address
 305 */
 306static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
 307				  struct btrfs_path *path, u64 time_seq,
 308				  struct __prelim_ref *ref,
 309				  struct ulist *parents,
 310				  const u64 *extent_item_pos, u64 total_refs)
 
 311{
 
 312	struct btrfs_root *root;
 313	struct btrfs_key root_key;
 314	struct extent_buffer *eb;
 315	int ret = 0;
 316	int root_level;
 317	int level = ref->level;
 318	int index;
 
 
 
 
 319
 320	root_key.objectid = ref->root_id;
 321	root_key.type = BTRFS_ROOT_ITEM_KEY;
 322	root_key.offset = (u64)-1;
 323
 324	index = srcu_read_lock(&fs_info->subvol_srcu);
 325
 326	root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 327	if (IS_ERR(root)) {
 328		srcu_read_unlock(&fs_info->subvol_srcu, index);
 329		ret = PTR_ERR(root);
 330		goto out;
 331	}
 332
 333	if (path->search_commit_root)
 334		root_level = btrfs_header_level(root->commit_root);
 335	else
 336		root_level = btrfs_old_root_level(root, time_seq);
 337
 338	if (root_level + 1 == level) {
 339		srcu_read_unlock(&fs_info->subvol_srcu, index);
 340		goto out;
 341	}
 342
 343	path->lowest_level = level;
 344	ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
 345
 346	/* root node has been locked, we can release @subvol_srcu safely here */
 347	srcu_read_unlock(&fs_info->subvol_srcu, index);
 348
 349	pr_debug("search slot in root %llu (level %d, ref count %d) returned "
 350		 "%d for key (%llu %u %llu)\n",
 351		 ref->root_id, level, ref->count, ret,
 352		 ref->key_for_search.objectid, ref->key_for_search.type,
 353		 ref->key_for_search.offset);
 
 354	if (ret < 0)
 355		goto out;
 356
 357	eb = path->nodes[level];
 358	while (!eb) {
 359		if (WARN_ON(!level)) {
 
 360			ret = 1;
 361			goto out;
 362		}
 363		level--;
 364		eb = path->nodes[level];
 365	}
 366
 367	ret = add_all_parents(root, path, parents, ref, level, time_seq,
 368			      extent_item_pos, total_refs);
 
 369out:
 370	path->lowest_level = 0;
 371	btrfs_release_path(path);
 372	return ret;
 373}
 374
 375/*
 376 * resolve all indirect backrefs from the list
 377 */
 378static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
 379				   struct btrfs_path *path, u64 time_seq,
 380				   struct list_head *head,
 381				   const u64 *extent_item_pos, u64 total_refs)
 382{
 383	int err;
 384	int ret = 0;
 385	struct __prelim_ref *ref;
 386	struct __prelim_ref *ref_safe;
 387	struct __prelim_ref *new_ref;
 388	struct ulist *parents;
 389	struct ulist_node *node;
 390	struct ulist_iterator uiter;
 391
 392	parents = ulist_alloc(GFP_NOFS);
 393	if (!parents)
 394		return -ENOMEM;
 395
 396	/*
 397	 * _safe allows us to insert directly after the current item without
 398	 * iterating over the newly inserted items.
 399	 * we're also allowed to re-assign ref during iteration.
 400	 */
 401	list_for_each_entry_safe(ref, ref_safe, head, list) {
 402		if (ref->parent)	/* already direct */
 403			continue;
 404		if (ref->count == 0)
 405			continue;
 406		err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
 407					     parents, extent_item_pos,
 408					     total_refs);
 409		/*
 410		 * we can only tolerate ENOENT,otherwise,we should catch error
 411		 * and return directly.
 412		 */
 413		if (err == -ENOENT) {
 414			continue;
 415		} else if (err) {
 416			ret = err;
 417			goto out;
 418		}
 419
 420		/* we put the first parent into the ref at hand */
 421		ULIST_ITER_INIT(&uiter);
 422		node = ulist_next(parents, &uiter);
 423		ref->parent = node ? node->val : 0;
 424		ref->inode_list = node ?
 425			(struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
 426
 427		/* additional parents require new refs being added here */
 428		while ((node = ulist_next(parents, &uiter))) {
 429			new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
 430						   GFP_NOFS);
 431			if (!new_ref) {
 432				ret = -ENOMEM;
 433				goto out;
 434			}
 435			memcpy(new_ref, ref, sizeof(*ref));
 436			new_ref->parent = node->val;
 437			new_ref->inode_list = (struct extent_inode_elem *)
 438							(uintptr_t)node->aux;
 439			list_add(&new_ref->list, &ref->list);
 440		}
 441		ulist_reinit(parents);
 442	}
 443out:
 444	ulist_free(parents);
 445	return ret;
 446}
 447
 448static inline int ref_for_same_block(struct __prelim_ref *ref1,
 449				     struct __prelim_ref *ref2)
 450{
 451	if (ref1->level != ref2->level)
 452		return 0;
 453	if (ref1->root_id != ref2->root_id)
 454		return 0;
 455	if (ref1->key_for_search.type != ref2->key_for_search.type)
 456		return 0;
 457	if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
 458		return 0;
 459	if (ref1->key_for_search.offset != ref2->key_for_search.offset)
 460		return 0;
 461	if (ref1->parent != ref2->parent)
 462		return 0;
 463
 464	return 1;
 465}
 466
 467/*
 468 * read tree blocks and add keys where required.
 469 */
 470static int __add_missing_keys(struct btrfs_fs_info *fs_info,
 471			      struct list_head *head)
 472{
 473	struct list_head *pos;
 474	struct extent_buffer *eb;
 475
 476	list_for_each(pos, head) {
 477		struct __prelim_ref *ref;
 478		ref = list_entry(pos, struct __prelim_ref, list);
 479
 480		if (ref->parent)
 481			continue;
 482		if (ref->key_for_search.type)
 483			continue;
 484		BUG_ON(!ref->wanted_disk_byte);
 485		eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
 486				     fs_info->tree_root->leafsize, 0);
 487		if (!eb || !extent_buffer_uptodate(eb)) {
 488			free_extent_buffer(eb);
 489			return -EIO;
 490		}
 491		btrfs_tree_read_lock(eb);
 492		if (btrfs_header_level(eb) == 0)
 493			btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
 494		else
 495			btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
 496		btrfs_tree_read_unlock(eb);
 497		free_extent_buffer(eb);
 498	}
 499	return 0;
 500}
 501
 502/*
 503 * merge two lists of backrefs and adjust counts accordingly
 504 *
 505 * mode = 1: merge identical keys, if key is set
 506 *    FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
 507 *           additionally, we could even add a key range for the blocks we
 508 *           looked into to merge even more (-> replace unresolved refs by those
 509 *           having a parent).
 510 * mode = 2: merge identical parents
 511 */
 512static void __merge_refs(struct list_head *head, int mode)
 513{
 514	struct list_head *pos1;
 515
 516	list_for_each(pos1, head) {
 517		struct list_head *n2;
 518		struct list_head *pos2;
 519		struct __prelim_ref *ref1;
 520
 521		ref1 = list_entry(pos1, struct __prelim_ref, list);
 522
 523		for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
 524		     pos2 = n2, n2 = pos2->next) {
 525			struct __prelim_ref *ref2;
 526			struct __prelim_ref *xchg;
 527			struct extent_inode_elem *eie;
 528
 529			ref2 = list_entry(pos2, struct __prelim_ref, list);
 530
 531			if (mode == 1) {
 532				if (!ref_for_same_block(ref1, ref2))
 533					continue;
 534				if (!ref1->parent && ref2->parent) {
 535					xchg = ref1;
 536					ref1 = ref2;
 537					ref2 = xchg;
 538				}
 
 539			} else {
 540				if (ref1->parent != ref2->parent)
 541					continue;
 
 542			}
 543
 544			eie = ref1->inode_list;
 545			while (eie && eie->next)
 546				eie = eie->next;
 547			if (eie)
 548				eie->next = ref2->inode_list;
 549			else
 550				ref1->inode_list = ref2->inode_list;
 551			ref1->count += ref2->count;
 552
 553			list_del(&ref2->list);
 554			kmem_cache_free(btrfs_prelim_ref_cache, ref2);
 555		}
 556
 557	}
 
 558}
 559
 560/*
 561 * add all currently queued delayed refs from this head whose seq nr is
 562 * smaller or equal that seq to the list
 563 */
 564static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
 565			      struct list_head *prefs, u64 *total_refs)
 566{
 567	struct btrfs_delayed_extent_op *extent_op = head->extent_op;
 568	struct rb_node *n = &head->node.rb_node;
 569	struct btrfs_key key;
 570	struct btrfs_key op_key = {0};
 571	int sgn;
 572	int ret = 0;
 573
 574	if (extent_op && extent_op->update_key)
 575		btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
 576
 577	spin_lock(&head->lock);
 578	n = rb_first(&head->ref_root);
 579	while (n) {
 580		struct btrfs_delayed_ref_node *node;
 581		node = rb_entry(n, struct btrfs_delayed_ref_node,
 582				rb_node);
 583		n = rb_next(n);
 
 
 
 584		if (node->seq > seq)
 585			continue;
 586
 587		switch (node->action) {
 588		case BTRFS_ADD_DELAYED_EXTENT:
 589		case BTRFS_UPDATE_DELAYED_HEAD:
 590			WARN_ON(1);
 591			continue;
 592		case BTRFS_ADD_DELAYED_REF:
 593			sgn = 1;
 594			break;
 595		case BTRFS_DROP_DELAYED_REF:
 596			sgn = -1;
 597			break;
 598		default:
 599			BUG_ON(1);
 600		}
 601		*total_refs += (node->ref_mod * sgn);
 602		switch (node->type) {
 603		case BTRFS_TREE_BLOCK_REF_KEY: {
 604			struct btrfs_delayed_tree_ref *ref;
 605
 606			ref = btrfs_delayed_node_to_tree_ref(node);
 607			ret = __add_prelim_ref(prefs, ref->root, &op_key,
 608					       ref->level + 1, 0, node->bytenr,
 609					       node->ref_mod * sgn, GFP_ATOMIC);
 610			break;
 611		}
 612		case BTRFS_SHARED_BLOCK_REF_KEY: {
 613			struct btrfs_delayed_tree_ref *ref;
 614
 615			ref = btrfs_delayed_node_to_tree_ref(node);
 616			ret = __add_prelim_ref(prefs, ref->root, NULL,
 617					       ref->level + 1, ref->parent,
 618					       node->bytenr,
 619					       node->ref_mod * sgn, GFP_ATOMIC);
 620			break;
 621		}
 622		case BTRFS_EXTENT_DATA_REF_KEY: {
 623			struct btrfs_delayed_data_ref *ref;
 624			ref = btrfs_delayed_node_to_data_ref(node);
 625
 626			key.objectid = ref->objectid;
 627			key.type = BTRFS_EXTENT_DATA_KEY;
 628			key.offset = ref->offset;
 629			ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
 630					       node->bytenr,
 631					       node->ref_mod * sgn, GFP_ATOMIC);
 632			break;
 633		}
 634		case BTRFS_SHARED_DATA_REF_KEY: {
 635			struct btrfs_delayed_data_ref *ref;
 636
 637			ref = btrfs_delayed_node_to_data_ref(node);
 638
 639			key.objectid = ref->objectid;
 640			key.type = BTRFS_EXTENT_DATA_KEY;
 641			key.offset = ref->offset;
 642			ret = __add_prelim_ref(prefs, ref->root, &key, 0,
 643					       ref->parent, node->bytenr,
 644					       node->ref_mod * sgn, GFP_ATOMIC);
 645			break;
 646		}
 647		default:
 648			WARN_ON(1);
 649		}
 650		if (ret)
 651			break;
 652	}
 653	spin_unlock(&head->lock);
 654	return ret;
 655}
 656
 657/*
 658 * add all inline backrefs for bytenr to the list
 659 */
 660static int __add_inline_refs(struct btrfs_fs_info *fs_info,
 661			     struct btrfs_path *path, u64 bytenr,
 662			     int *info_level, struct list_head *prefs,
 663			     u64 *total_refs)
 664{
 665	int ret = 0;
 666	int slot;
 667	struct extent_buffer *leaf;
 668	struct btrfs_key key;
 669	struct btrfs_key found_key;
 670	unsigned long ptr;
 671	unsigned long end;
 672	struct btrfs_extent_item *ei;
 673	u64 flags;
 674	u64 item_size;
 675
 676	/*
 677	 * enumerate all inline refs
 678	 */
 679	leaf = path->nodes[0];
 680	slot = path->slots[0];
 681
 682	item_size = btrfs_item_size_nr(leaf, slot);
 683	BUG_ON(item_size < sizeof(*ei));
 684
 685	ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 686	flags = btrfs_extent_flags(leaf, ei);
 687	*total_refs += btrfs_extent_refs(leaf, ei);
 688	btrfs_item_key_to_cpu(leaf, &found_key, slot);
 689
 690	ptr = (unsigned long)(ei + 1);
 691	end = (unsigned long)ei + item_size;
 692
 693	if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
 694	    flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 695		struct btrfs_tree_block_info *info;
 696
 697		info = (struct btrfs_tree_block_info *)ptr;
 698		*info_level = btrfs_tree_block_level(leaf, info);
 699		ptr += sizeof(struct btrfs_tree_block_info);
 700		BUG_ON(ptr > end);
 701	} else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
 702		*info_level = found_key.offset;
 703	} else {
 704		BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
 705	}
 706
 707	while (ptr < end) {
 708		struct btrfs_extent_inline_ref *iref;
 709		u64 offset;
 710		int type;
 711
 712		iref = (struct btrfs_extent_inline_ref *)ptr;
 713		type = btrfs_extent_inline_ref_type(leaf, iref);
 714		offset = btrfs_extent_inline_ref_offset(leaf, iref);
 715
 716		switch (type) {
 717		case BTRFS_SHARED_BLOCK_REF_KEY:
 718			ret = __add_prelim_ref(prefs, 0, NULL,
 719						*info_level + 1, offset,
 720						bytenr, 1, GFP_NOFS);
 721			break;
 722		case BTRFS_SHARED_DATA_REF_KEY: {
 723			struct btrfs_shared_data_ref *sdref;
 724			int count;
 725
 726			sdref = (struct btrfs_shared_data_ref *)(iref + 1);
 727			count = btrfs_shared_data_ref_count(leaf, sdref);
 728			ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
 729					       bytenr, count, GFP_NOFS);
 730			break;
 731		}
 732		case BTRFS_TREE_BLOCK_REF_KEY:
 733			ret = __add_prelim_ref(prefs, offset, NULL,
 734					       *info_level + 1, 0,
 735					       bytenr, 1, GFP_NOFS);
 736			break;
 737		case BTRFS_EXTENT_DATA_REF_KEY: {
 738			struct btrfs_extent_data_ref *dref;
 739			int count;
 740			u64 root;
 741
 742			dref = (struct btrfs_extent_data_ref *)(&iref->offset);
 743			count = btrfs_extent_data_ref_count(leaf, dref);
 744			key.objectid = btrfs_extent_data_ref_objectid(leaf,
 745								      dref);
 746			key.type = BTRFS_EXTENT_DATA_KEY;
 747			key.offset = btrfs_extent_data_ref_offset(leaf, dref);
 748			root = btrfs_extent_data_ref_root(leaf, dref);
 749			ret = __add_prelim_ref(prefs, root, &key, 0, 0,
 750					       bytenr, count, GFP_NOFS);
 751			break;
 752		}
 753		default:
 754			WARN_ON(1);
 755		}
 756		if (ret)
 757			return ret;
 758		ptr += btrfs_extent_inline_ref_size(type);
 759	}
 760
 761	return 0;
 762}
 763
 764/*
 765 * add all non-inline backrefs for bytenr to the list
 766 */
 767static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
 768			    struct btrfs_path *path, u64 bytenr,
 769			    int info_level, struct list_head *prefs)
 770{
 771	struct btrfs_root *extent_root = fs_info->extent_root;
 772	int ret;
 773	int slot;
 774	struct extent_buffer *leaf;
 775	struct btrfs_key key;
 776
 777	while (1) {
 778		ret = btrfs_next_item(extent_root, path);
 779		if (ret < 0)
 780			break;
 781		if (ret) {
 782			ret = 0;
 783			break;
 784		}
 785
 786		slot = path->slots[0];
 787		leaf = path->nodes[0];
 788		btrfs_item_key_to_cpu(leaf, &key, slot);
 789
 790		if (key.objectid != bytenr)
 791			break;
 792		if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
 793			continue;
 794		if (key.type > BTRFS_SHARED_DATA_REF_KEY)
 795			break;
 796
 797		switch (key.type) {
 798		case BTRFS_SHARED_BLOCK_REF_KEY:
 799			ret = __add_prelim_ref(prefs, 0, NULL,
 800						info_level + 1, key.offset,
 801						bytenr, 1, GFP_NOFS);
 802			break;
 803		case BTRFS_SHARED_DATA_REF_KEY: {
 804			struct btrfs_shared_data_ref *sdref;
 805			int count;
 806
 807			sdref = btrfs_item_ptr(leaf, slot,
 808					      struct btrfs_shared_data_ref);
 809			count = btrfs_shared_data_ref_count(leaf, sdref);
 810			ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
 811						bytenr, count, GFP_NOFS);
 812			break;
 813		}
 814		case BTRFS_TREE_BLOCK_REF_KEY:
 815			ret = __add_prelim_ref(prefs, key.offset, NULL,
 816					       info_level + 1, 0,
 817					       bytenr, 1, GFP_NOFS);
 818			break;
 819		case BTRFS_EXTENT_DATA_REF_KEY: {
 820			struct btrfs_extent_data_ref *dref;
 821			int count;
 822			u64 root;
 823
 824			dref = btrfs_item_ptr(leaf, slot,
 825					      struct btrfs_extent_data_ref);
 826			count = btrfs_extent_data_ref_count(leaf, dref);
 827			key.objectid = btrfs_extent_data_ref_objectid(leaf,
 828								      dref);
 829			key.type = BTRFS_EXTENT_DATA_KEY;
 830			key.offset = btrfs_extent_data_ref_offset(leaf, dref);
 831			root = btrfs_extent_data_ref_root(leaf, dref);
 832			ret = __add_prelim_ref(prefs, root, &key, 0, 0,
 833					       bytenr, count, GFP_NOFS);
 834			break;
 835		}
 836		default:
 837			WARN_ON(1);
 838		}
 839		if (ret)
 840			return ret;
 841
 842	}
 843
 844	return ret;
 845}
 846
 847/*
 848 * this adds all existing backrefs (inline backrefs, backrefs and delayed
 849 * refs) for the given bytenr to the refs list, merges duplicates and resolves
 850 * indirect refs to their parent bytenr.
 851 * When roots are found, they're added to the roots list
 852 *
 853 * FIXME some caching might speed things up
 854 */
 855static int find_parent_nodes(struct btrfs_trans_handle *trans,
 856			     struct btrfs_fs_info *fs_info, u64 bytenr,
 857			     u64 time_seq, struct ulist *refs,
 858			     struct ulist *roots, const u64 *extent_item_pos)
 
 859{
 860	struct btrfs_key key;
 861	struct btrfs_path *path;
 862	struct btrfs_delayed_ref_root *delayed_refs = NULL;
 863	struct btrfs_delayed_ref_head *head;
 864	int info_level = 0;
 865	int ret;
 
 866	struct list_head prefs_delayed;
 867	struct list_head prefs;
 868	struct __prelim_ref *ref;
 869	struct extent_inode_elem *eie = NULL;
 870	u64 total_refs = 0;
 871
 872	INIT_LIST_HEAD(&prefs);
 873	INIT_LIST_HEAD(&prefs_delayed);
 874
 875	key.objectid = bytenr;
 
 876	key.offset = (u64)-1;
 877	if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
 878		key.type = BTRFS_METADATA_ITEM_KEY;
 879	else
 880		key.type = BTRFS_EXTENT_ITEM_KEY;
 881
 882	path = btrfs_alloc_path();
 883	if (!path)
 884		return -ENOMEM;
 885	if (!trans) {
 886		path->search_commit_root = 1;
 887		path->skip_locking = 1;
 888	}
 889
 890	/*
 891	 * grab both a lock on the path and a lock on the delayed ref head.
 892	 * We need both to get a consistent picture of how the refs look
 893	 * at a specified point in time
 894	 */
 895again:
 896	head = NULL;
 897
 898	ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
 899	if (ret < 0)
 900		goto out;
 901	BUG_ON(ret == 0);
 902
 903	if (trans) {
 904		/*
 905		 * look if there are updates for this ref queued and lock the
 906		 * head
 907		 */
 908		delayed_refs = &trans->transaction->delayed_refs;
 909		spin_lock(&delayed_refs->lock);
 910		head = btrfs_find_delayed_ref_head(trans, bytenr);
 911		if (head) {
 912			if (!mutex_trylock(&head->mutex)) {
 913				atomic_inc(&head->node.refs);
 914				spin_unlock(&delayed_refs->lock);
 915
 916				btrfs_release_path(path);
 917
 918				/*
 919				 * Mutex was contended, block until it's
 920				 * released and try again
 921				 */
 922				mutex_lock(&head->mutex);
 923				mutex_unlock(&head->mutex);
 924				btrfs_put_delayed_ref(&head->node);
 925				goto again;
 926			}
 927			spin_unlock(&delayed_refs->lock);
 928			ret = __add_delayed_refs(head, time_seq,
 929						 &prefs_delayed, &total_refs);
 930			mutex_unlock(&head->mutex);
 931			if (ret)
 
 932				goto out;
 933		} else {
 934			spin_unlock(&delayed_refs->lock);
 935		}
 
 936	}
 937
 938	if (path->slots[0]) {
 939		struct extent_buffer *leaf;
 940		int slot;
 941
 942		path->slots[0]--;
 943		leaf = path->nodes[0];
 944		slot = path->slots[0];
 945		btrfs_item_key_to_cpu(leaf, &key, slot);
 946		if (key.objectid == bytenr &&
 947		    (key.type == BTRFS_EXTENT_ITEM_KEY ||
 948		     key.type == BTRFS_METADATA_ITEM_KEY)) {
 949			ret = __add_inline_refs(fs_info, path, bytenr,
 950						&info_level, &prefs,
 951						&total_refs);
 952			if (ret)
 953				goto out;
 954			ret = __add_keyed_refs(fs_info, path, bytenr,
 955					       info_level, &prefs);
 956			if (ret)
 957				goto out;
 958		}
 959	}
 960	btrfs_release_path(path);
 961
 962	list_splice_init(&prefs_delayed, &prefs);
 963
 964	ret = __add_missing_keys(fs_info, &prefs);
 965	if (ret)
 966		goto out;
 967
 968	__merge_refs(&prefs, 1);
 
 
 969
 970	ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
 971				      extent_item_pos, total_refs);
 972	if (ret)
 973		goto out;
 974
 975	__merge_refs(&prefs, 2);
 
 
 976
 977	while (!list_empty(&prefs)) {
 978		ref = list_first_entry(&prefs, struct __prelim_ref, list);
 979		WARN_ON(ref->count < 0);
 980		if (roots && ref->count && ref->root_id && ref->parent == 0) {
 
 
 981			/* no parent == root of tree */
 982			ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
 983			if (ret < 0)
 984				goto out;
 985		}
 986		if (ref->count && ref->parent) {
 
 987			if (extent_item_pos && !ref->inode_list) {
 988				u32 bsz;
 989				struct extent_buffer *eb;
 990				bsz = btrfs_level_size(fs_info->extent_root,
 991							info_level);
 992				eb = read_tree_block(fs_info->extent_root,
 993							   ref->parent, bsz, 0);
 994				if (!eb || !extent_buffer_uptodate(eb)) {
 995					free_extent_buffer(eb);
 996					ret = -EIO;
 997					goto out;
 998				}
 999				ret = find_extent_in_eb(eb, bytenr,
1000							*extent_item_pos, &eie);
1001				free_extent_buffer(eb);
1002				if (ret < 0)
1003					goto out;
1004				ref->inode_list = eie;
 
1005			}
1006			ret = ulist_add_merge(refs, ref->parent,
1007					      (uintptr_t)ref->inode_list,
1008					      (u64 *)&eie, GFP_NOFS);
1009			if (ret < 0)
1010				goto out;
1011			if (!ret && extent_item_pos) {
1012				/*
1013				 * we've recorded that parent, so we must extend
1014				 * its inode list here
1015				 */
1016				BUG_ON(!eie);
1017				while (eie->next)
1018					eie = eie->next;
1019				eie->next = ref->inode_list;
1020			}
1021			eie = NULL;
1022		}
1023		list_del(&ref->list);
1024		kmem_cache_free(btrfs_prelim_ref_cache, ref);
1025	}
1026
1027out:
1028	btrfs_free_path(path);
1029	while (!list_empty(&prefs)) {
1030		ref = list_first_entry(&prefs, struct __prelim_ref, list);
1031		list_del(&ref->list);
1032		kmem_cache_free(btrfs_prelim_ref_cache, ref);
1033	}
1034	while (!list_empty(&prefs_delayed)) {
1035		ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
1036				       list);
1037		list_del(&ref->list);
1038		kmem_cache_free(btrfs_prelim_ref_cache, ref);
1039	}
1040	if (ret < 0)
1041		free_inode_elem_list(eie);
1042	return ret;
1043}
1044
1045static void free_leaf_list(struct ulist *blocks)
1046{
1047	struct ulist_node *node = NULL;
1048	struct extent_inode_elem *eie;
 
1049	struct ulist_iterator uiter;
1050
1051	ULIST_ITER_INIT(&uiter);
1052	while ((node = ulist_next(blocks, &uiter))) {
1053		if (!node->aux)
1054			continue;
1055		eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1056		free_inode_elem_list(eie);
 
 
 
1057		node->aux = 0;
1058	}
1059
1060	ulist_free(blocks);
1061}
1062
1063/*
1064 * Finds all leafs with a reference to the specified combination of bytenr and
1065 * offset. key_list_head will point to a list of corresponding keys (caller must
1066 * free each list element). The leafs will be stored in the leafs ulist, which
1067 * must be freed with ulist_free.
1068 *
1069 * returns 0 on success, <0 on error
1070 */
1071static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1072				struct btrfs_fs_info *fs_info, u64 bytenr,
1073				u64 time_seq, struct ulist **leafs,
 
1074				const u64 *extent_item_pos)
1075{
 
1076	int ret;
1077
 
 
 
1078	*leafs = ulist_alloc(GFP_NOFS);
1079	if (!*leafs)
 
1080		return -ENOMEM;
 
 
 
 
 
1081
1082	ret = find_parent_nodes(trans, fs_info, bytenr,
1083				time_seq, *leafs, NULL, extent_item_pos);
1084	if (ret < 0 && ret != -ENOENT) {
1085		free_leaf_list(*leafs);
1086		return ret;
1087	}
1088
1089	return 0;
1090}
1091
1092/*
1093 * walk all backrefs for a given extent to find all roots that reference this
1094 * extent. Walking a backref means finding all extents that reference this
1095 * extent and in turn walk the backrefs of those, too. Naturally this is a
1096 * recursive process, but here it is implemented in an iterative fashion: We
1097 * find all referencing extents for the extent in question and put them on a
1098 * list. In turn, we find all referencing extents for those, further appending
1099 * to the list. The way we iterate the list allows adding more elements after
1100 * the current while iterating. The process stops when we reach the end of the
1101 * list. Found roots are added to the roots list.
1102 *
1103 * returns 0 on success, < 0 on error.
1104 */
1105static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1106				  struct btrfs_fs_info *fs_info, u64 bytenr,
1107				  u64 time_seq, struct ulist **roots)
 
1108{
1109	struct ulist *tmp;
1110	struct ulist_node *node = NULL;
1111	struct ulist_iterator uiter;
1112	int ret;
1113
1114	tmp = ulist_alloc(GFP_NOFS);
1115	if (!tmp)
1116		return -ENOMEM;
1117	*roots = ulist_alloc(GFP_NOFS);
1118	if (!*roots) {
1119		ulist_free(tmp);
1120		return -ENOMEM;
1121	}
1122
1123	ULIST_ITER_INIT(&uiter);
1124	while (1) {
1125		ret = find_parent_nodes(trans, fs_info, bytenr,
1126					time_seq, tmp, *roots, NULL);
1127		if (ret < 0 && ret != -ENOENT) {
1128			ulist_free(tmp);
1129			ulist_free(*roots);
1130			return ret;
1131		}
1132		node = ulist_next(tmp, &uiter);
1133		if (!node)
1134			break;
1135		bytenr = node->val;
1136		cond_resched();
1137	}
1138
1139	ulist_free(tmp);
1140	return 0;
1141}
1142
1143int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1144			 struct btrfs_fs_info *fs_info, u64 bytenr,
1145			 u64 time_seq, struct ulist **roots)
 
1146{
1147	int ret;
 
 
1148
1149	if (!trans)
1150		down_read(&fs_info->commit_root_sem);
1151	ret = __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots);
1152	if (!trans)
1153		up_read(&fs_info->commit_root_sem);
1154	return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1155}
1156
1157/*
1158 * this makes the path point to (inum INODE_ITEM ioff)
1159 */
1160int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1161			struct btrfs_path *path)
1162{
1163	struct btrfs_key key;
1164	return btrfs_find_item(fs_root, path, inum, ioff,
1165			BTRFS_INODE_ITEM_KEY, &key);
1166}
1167
1168static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1169				struct btrfs_path *path,
1170				struct btrfs_key *found_key)
1171{
1172	return btrfs_find_item(fs_root, path, inum, ioff,
1173			BTRFS_INODE_REF_KEY, found_key);
1174}
1175
1176int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1177			  u64 start_off, struct btrfs_path *path,
1178			  struct btrfs_inode_extref **ret_extref,
1179			  u64 *found_off)
1180{
1181	int ret, slot;
1182	struct btrfs_key key;
1183	struct btrfs_key found_key;
1184	struct btrfs_inode_extref *extref;
1185	struct extent_buffer *leaf;
1186	unsigned long ptr;
1187
1188	key.objectid = inode_objectid;
1189	btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1190	key.offset = start_off;
1191
1192	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1193	if (ret < 0)
1194		return ret;
1195
1196	while (1) {
1197		leaf = path->nodes[0];
1198		slot = path->slots[0];
1199		if (slot >= btrfs_header_nritems(leaf)) {
1200			/*
1201			 * If the item at offset is not found,
1202			 * btrfs_search_slot will point us to the slot
1203			 * where it should be inserted. In our case
1204			 * that will be the slot directly before the
1205			 * next INODE_REF_KEY_V2 item. In the case
1206			 * that we're pointing to the last slot in a
1207			 * leaf, we must move one leaf over.
1208			 */
1209			ret = btrfs_next_leaf(root, path);
1210			if (ret) {
1211				if (ret >= 1)
1212					ret = -ENOENT;
1213				break;
1214			}
1215			continue;
1216		}
1217
1218		btrfs_item_key_to_cpu(leaf, &found_key, slot);
1219
1220		/*
1221		 * Check that we're still looking at an extended ref key for
1222		 * this particular objectid. If we have different
1223		 * objectid or type then there are no more to be found
1224		 * in the tree and we can exit.
1225		 */
1226		ret = -ENOENT;
1227		if (found_key.objectid != inode_objectid)
1228			break;
1229		if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1230			break;
1231
1232		ret = 0;
1233		ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1234		extref = (struct btrfs_inode_extref *)ptr;
1235		*ret_extref = extref;
1236		if (found_off)
1237			*found_off = found_key.offset;
1238		break;
1239	}
1240
1241	return ret;
1242}
1243
1244/*
1245 * this iterates to turn a name (from iref/extref) into a full filesystem path.
1246 * Elements of the path are separated by '/' and the path is guaranteed to be
1247 * 0-terminated. the path is only given within the current file system.
1248 * Therefore, it never starts with a '/'. the caller is responsible to provide
1249 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1250 * the start point of the resulting string is returned. this pointer is within
1251 * dest, normally.
1252 * in case the path buffer would overflow, the pointer is decremented further
1253 * as if output was written to the buffer, though no more output is actually
1254 * generated. that way, the caller can determine how much space would be
1255 * required for the path to fit into the buffer. in that case, the returned
1256 * value will be smaller than dest. callers must check this!
1257 */
1258char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1259			u32 name_len, unsigned long name_off,
1260			struct extent_buffer *eb_in, u64 parent,
1261			char *dest, u32 size)
1262{
 
1263	int slot;
1264	u64 next_inum;
1265	int ret;
1266	s64 bytes_left = ((s64)size) - 1;
1267	struct extent_buffer *eb = eb_in;
1268	struct btrfs_key found_key;
1269	int leave_spinning = path->leave_spinning;
1270	struct btrfs_inode_ref *iref;
1271
1272	if (bytes_left >= 0)
1273		dest[bytes_left] = '\0';
1274
1275	path->leave_spinning = 1;
1276	while (1) {
1277		bytes_left -= name_len;
 
1278		if (bytes_left >= 0)
1279			read_extent_buffer(eb, dest + bytes_left,
1280					   name_off, name_len);
1281		if (eb != eb_in) {
1282			btrfs_tree_read_unlock_blocking(eb);
1283			free_extent_buffer(eb);
1284		}
1285		ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1286		if (ret > 0)
1287			ret = -ENOENT;
1288		if (ret)
1289			break;
1290
1291		next_inum = found_key.offset;
1292
1293		/* regular exit ahead */
1294		if (parent == next_inum)
1295			break;
1296
1297		slot = path->slots[0];
1298		eb = path->nodes[0];
1299		/* make sure we can use eb after releasing the path */
1300		if (eb != eb_in) {
1301			atomic_inc(&eb->refs);
1302			btrfs_tree_read_lock(eb);
1303			btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1304		}
1305		btrfs_release_path(path);
1306		iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1307
1308		name_len = btrfs_inode_ref_name_len(eb, iref);
1309		name_off = (unsigned long)(iref + 1);
1310
 
1311		parent = next_inum;
1312		--bytes_left;
1313		if (bytes_left >= 0)
1314			dest[bytes_left] = '/';
1315	}
1316
1317	btrfs_release_path(path);
1318	path->leave_spinning = leave_spinning;
1319
1320	if (ret)
1321		return ERR_PTR(ret);
1322
1323	return dest + bytes_left;
1324}
1325
1326/*
1327 * this makes the path point to (logical EXTENT_ITEM *)
1328 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1329 * tree blocks and <0 on error.
1330 */
1331int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1332			struct btrfs_path *path, struct btrfs_key *found_key,
1333			u64 *flags_ret)
1334{
1335	int ret;
1336	u64 flags;
1337	u64 size = 0;
1338	u32 item_size;
1339	struct extent_buffer *eb;
1340	struct btrfs_extent_item *ei;
1341	struct btrfs_key key;
1342
1343	if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1344		key.type = BTRFS_METADATA_ITEM_KEY;
1345	else
1346		key.type = BTRFS_EXTENT_ITEM_KEY;
1347	key.objectid = logical;
1348	key.offset = (u64)-1;
1349
1350	ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1351	if (ret < 0)
1352		return ret;
1353
1354	ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
1355	if (ret) {
1356		if (ret > 0)
1357			ret = -ENOENT;
1358		return ret;
1359	}
1360	btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1361	if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1362		size = fs_info->extent_root->leafsize;
1363	else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1364		size = found_key->offset;
1365
1366	if (found_key->objectid > logical ||
1367	    found_key->objectid + size <= logical) {
1368		pr_debug("logical %llu is not within any extent\n", logical);
1369		return -ENOENT;
1370	}
1371
1372	eb = path->nodes[0];
1373	item_size = btrfs_item_size_nr(eb, path->slots[0]);
1374	BUG_ON(item_size < sizeof(*ei));
1375
1376	ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1377	flags = btrfs_extent_flags(eb, ei);
1378
1379	pr_debug("logical %llu is at position %llu within the extent (%llu "
1380		 "EXTENT_ITEM %llu) flags %#llx size %u\n",
1381		 logical, logical - found_key->objectid, found_key->objectid,
1382		 found_key->offset, flags, item_size);
1383
1384	WARN_ON(!flags_ret);
1385	if (flags_ret) {
1386		if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1387			*flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1388		else if (flags & BTRFS_EXTENT_FLAG_DATA)
1389			*flags_ret = BTRFS_EXTENT_FLAG_DATA;
1390		else
1391			BUG_ON(1);
1392		return 0;
1393	}
1394
1395	return -EIO;
1396}
1397
1398/*
1399 * helper function to iterate extent inline refs. ptr must point to a 0 value
1400 * for the first call and may be modified. it is used to track state.
1401 * if more refs exist, 0 is returned and the next call to
1402 * __get_extent_inline_ref must pass the modified ptr parameter to get the
1403 * next ref. after the last ref was processed, 1 is returned.
1404 * returns <0 on error
1405 */
1406static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1407				struct btrfs_extent_item *ei, u32 item_size,
1408				struct btrfs_extent_inline_ref **out_eiref,
1409				int *out_type)
1410{
1411	unsigned long end;
1412	u64 flags;
1413	struct btrfs_tree_block_info *info;
1414
1415	if (!*ptr) {
1416		/* first call */
1417		flags = btrfs_extent_flags(eb, ei);
1418		if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1419			info = (struct btrfs_tree_block_info *)(ei + 1);
1420			*out_eiref =
1421				(struct btrfs_extent_inline_ref *)(info + 1);
1422		} else {
1423			*out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1424		}
1425		*ptr = (unsigned long)*out_eiref;
1426		if ((void *)*ptr >= (void *)ei + item_size)
1427			return -ENOENT;
1428	}
1429
1430	end = (unsigned long)ei + item_size;
1431	*out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1432	*out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1433
1434	*ptr += btrfs_extent_inline_ref_size(*out_type);
1435	WARN_ON(*ptr > end);
1436	if (*ptr == end)
1437		return 1; /* last */
1438
1439	return 0;
1440}
1441
1442/*
1443 * reads the tree block backref for an extent. tree level and root are returned
1444 * through out_level and out_root. ptr must point to a 0 value for the first
1445 * call and may be modified (see __get_extent_inline_ref comment).
1446 * returns 0 if data was provided, 1 if there was no more data to provide or
1447 * <0 on error.
1448 */
1449int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1450				struct btrfs_extent_item *ei, u32 item_size,
1451				u64 *out_root, u8 *out_level)
1452{
1453	int ret;
1454	int type;
1455	struct btrfs_tree_block_info *info;
1456	struct btrfs_extent_inline_ref *eiref;
1457
1458	if (*ptr == (unsigned long)-1)
1459		return 1;
1460
1461	while (1) {
1462		ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1463						&eiref, &type);
1464		if (ret < 0)
1465			return ret;
1466
1467		if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1468		    type == BTRFS_SHARED_BLOCK_REF_KEY)
1469			break;
1470
1471		if (ret == 1)
1472			return 1;
1473	}
1474
1475	/* we can treat both ref types equally here */
1476	info = (struct btrfs_tree_block_info *)(ei + 1);
1477	*out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1478	*out_level = btrfs_tree_block_level(eb, info);
1479
1480	if (ret == 1)
1481		*ptr = (unsigned long)-1;
1482
1483	return 0;
1484}
1485
1486static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1487				u64 root, u64 extent_item_objectid,
1488				iterate_extent_inodes_t *iterate, void *ctx)
1489{
1490	struct extent_inode_elem *eie;
1491	int ret = 0;
1492
1493	for (eie = inode_list; eie; eie = eie->next) {
1494		pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1495			 "root %llu\n", extent_item_objectid,
1496			 eie->inum, eie->offset, root);
1497		ret = iterate(eie->inum, eie->offset, root, ctx);
1498		if (ret) {
1499			pr_debug("stopping iteration for %llu due to ret=%d\n",
1500				 extent_item_objectid, ret);
1501			break;
1502		}
1503	}
1504
1505	return ret;
1506}
1507
1508/*
1509 * calls iterate() for every inode that references the extent identified by
1510 * the given parameters.
1511 * when the iterator function returns a non-zero value, iteration stops.
1512 */
1513int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1514				u64 extent_item_objectid, u64 extent_item_pos,
1515				int search_commit_root,
1516				iterate_extent_inodes_t *iterate, void *ctx)
1517{
1518	int ret;
1519	struct btrfs_trans_handle *trans = NULL;
 
 
1520	struct ulist *refs = NULL;
1521	struct ulist *roots = NULL;
1522	struct ulist_node *ref_node = NULL;
1523	struct ulist_node *root_node = NULL;
 
1524	struct seq_list tree_mod_seq_elem = {};
1525	struct ulist_iterator ref_uiter;
1526	struct ulist_iterator root_uiter;
 
1527
1528	pr_debug("resolving all inodes for extent %llu\n",
1529			extent_item_objectid);
1530
1531	if (!search_commit_root) {
 
 
1532		trans = btrfs_join_transaction(fs_info->extent_root);
1533		if (IS_ERR(trans))
1534			return PTR_ERR(trans);
 
 
 
 
 
1535		btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1536	} else {
1537		down_read(&fs_info->commit_root_sem);
1538	}
1539
1540	ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1541				   tree_mod_seq_elem.seq, &refs,
1542				   &extent_item_pos);
1543	if (ret)
1544		goto out;
1545
1546	ULIST_ITER_INIT(&ref_uiter);
1547	while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1548		ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val,
1549					     tree_mod_seq_elem.seq, &roots);
 
1550		if (ret)
1551			break;
1552		ULIST_ITER_INIT(&root_uiter);
1553		while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1554			pr_debug("root %llu references leaf %llu, data list "
1555				 "%#llx\n", root_node->val, ref_node->val,
1556				 ref_node->aux);
1557			ret = iterate_leaf_refs((struct extent_inode_elem *)
1558						(uintptr_t)ref_node->aux,
1559						root_node->val,
1560						extent_item_objectid,
1561						iterate, ctx);
1562		}
1563		ulist_free(roots);
 
1564	}
1565
1566	free_leaf_list(refs);
 
1567out:
1568	if (!search_commit_root) {
1569		btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
 
1570		btrfs_end_transaction(trans, fs_info->extent_root);
1571	} else {
1572		up_read(&fs_info->commit_root_sem);
1573	}
1574
1575	return ret;
1576}
1577
1578int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1579				struct btrfs_path *path,
1580				iterate_extent_inodes_t *iterate, void *ctx)
1581{
1582	int ret;
1583	u64 extent_item_pos;
1584	u64 flags = 0;
1585	struct btrfs_key found_key;
1586	int search_commit_root = path->search_commit_root;
1587
1588	ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
 
1589	btrfs_release_path(path);
 
 
1590	if (ret < 0)
1591		return ret;
1592	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1593		return -EINVAL;
1594
1595	extent_item_pos = logical - found_key.objectid;
1596	ret = iterate_extent_inodes(fs_info, found_key.objectid,
1597					extent_item_pos, search_commit_root,
1598					iterate, ctx);
1599
1600	return ret;
1601}
1602
1603typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1604			      struct extent_buffer *eb, void *ctx);
1605
1606static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1607			      struct btrfs_path *path,
1608			      iterate_irefs_t *iterate, void *ctx)
1609{
1610	int ret = 0;
1611	int slot;
1612	u32 cur;
1613	u32 len;
1614	u32 name_len;
1615	u64 parent = 0;
1616	int found = 0;
1617	struct extent_buffer *eb;
1618	struct btrfs_item *item;
1619	struct btrfs_inode_ref *iref;
1620	struct btrfs_key found_key;
1621
1622	while (!ret) {
 
1623		ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1624				     &found_key);
1625		if (ret < 0)
1626			break;
1627		if (ret) {
1628			ret = found ? 0 : -ENOENT;
1629			break;
1630		}
1631		++found;
1632
1633		parent = found_key.offset;
1634		slot = path->slots[0];
1635		eb = btrfs_clone_extent_buffer(path->nodes[0]);
1636		if (!eb) {
1637			ret = -ENOMEM;
1638			break;
1639		}
1640		extent_buffer_get(eb);
1641		btrfs_tree_read_lock(eb);
1642		btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1643		btrfs_release_path(path);
1644
1645		item = btrfs_item_nr(slot);
1646		iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1647
1648		for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1649			name_len = btrfs_inode_ref_name_len(eb, iref);
1650			/* path must be released before calling iterate()! */
1651			pr_debug("following ref at offset %u for inode %llu in "
1652				 "tree %llu\n", cur, found_key.objectid,
1653				 fs_root->objectid);
1654			ret = iterate(parent, name_len,
1655				      (unsigned long)(iref + 1), eb, ctx);
1656			if (ret)
1657				break;
1658			len = sizeof(*iref) + name_len;
1659			iref = (struct btrfs_inode_ref *)((char *)iref + len);
1660		}
1661		btrfs_tree_read_unlock_blocking(eb);
1662		free_extent_buffer(eb);
1663	}
1664
1665	btrfs_release_path(path);
1666
1667	return ret;
1668}
1669
1670static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1671				 struct btrfs_path *path,
1672				 iterate_irefs_t *iterate, void *ctx)
1673{
1674	int ret;
1675	int slot;
1676	u64 offset = 0;
1677	u64 parent;
1678	int found = 0;
1679	struct extent_buffer *eb;
1680	struct btrfs_inode_extref *extref;
1681	struct extent_buffer *leaf;
1682	u32 item_size;
1683	u32 cur_offset;
1684	unsigned long ptr;
1685
1686	while (1) {
1687		ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1688					    &offset);
1689		if (ret < 0)
1690			break;
1691		if (ret) {
1692			ret = found ? 0 : -ENOENT;
1693			break;
1694		}
1695		++found;
1696
1697		slot = path->slots[0];
1698		eb = btrfs_clone_extent_buffer(path->nodes[0]);
1699		if (!eb) {
1700			ret = -ENOMEM;
1701			break;
1702		}
1703		extent_buffer_get(eb);
1704
1705		btrfs_tree_read_lock(eb);
1706		btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1707		btrfs_release_path(path);
1708
1709		leaf = path->nodes[0];
1710		item_size = btrfs_item_size_nr(leaf, slot);
1711		ptr = btrfs_item_ptr_offset(leaf, slot);
1712		cur_offset = 0;
1713
1714		while (cur_offset < item_size) {
1715			u32 name_len;
1716
1717			extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1718			parent = btrfs_inode_extref_parent(eb, extref);
1719			name_len = btrfs_inode_extref_name_len(eb, extref);
1720			ret = iterate(parent, name_len,
1721				      (unsigned long)&extref->name, eb, ctx);
1722			if (ret)
1723				break;
1724
1725			cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1726			cur_offset += sizeof(*extref);
1727		}
1728		btrfs_tree_read_unlock_blocking(eb);
1729		free_extent_buffer(eb);
1730
1731		offset++;
1732	}
1733
1734	btrfs_release_path(path);
1735
1736	return ret;
1737}
1738
1739static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1740			 struct btrfs_path *path, iterate_irefs_t *iterate,
1741			 void *ctx)
1742{
1743	int ret;
1744	int found_refs = 0;
1745
1746	ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1747	if (!ret)
1748		++found_refs;
1749	else if (ret != -ENOENT)
1750		return ret;
1751
1752	ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1753	if (ret == -ENOENT && found_refs)
1754		return 0;
1755
1756	return ret;
1757}
1758
1759/*
1760 * returns 0 if the path could be dumped (probably truncated)
1761 * returns <0 in case of an error
1762 */
1763static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1764			 struct extent_buffer *eb, void *ctx)
1765{
1766	struct inode_fs_paths *ipath = ctx;
1767	char *fspath;
1768	char *fspath_min;
1769	int i = ipath->fspath->elem_cnt;
1770	const int s_ptr = sizeof(char *);
1771	u32 bytes_left;
1772
1773	bytes_left = ipath->fspath->bytes_left > s_ptr ?
1774					ipath->fspath->bytes_left - s_ptr : 0;
1775
1776	fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1777	fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1778				   name_off, eb, inum, fspath_min, bytes_left);
1779	if (IS_ERR(fspath))
1780		return PTR_ERR(fspath);
1781
1782	if (fspath > fspath_min) {
 
1783		ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1784		++ipath->fspath->elem_cnt;
1785		ipath->fspath->bytes_left = fspath - fspath_min;
1786	} else {
 
 
 
1787		++ipath->fspath->elem_missed;
1788		ipath->fspath->bytes_missing += fspath_min - fspath;
1789		ipath->fspath->bytes_left = 0;
1790	}
1791
1792	return 0;
1793}
1794
1795/*
1796 * this dumps all file system paths to the inode into the ipath struct, provided
1797 * is has been created large enough. each path is zero-terminated and accessed
1798 * from ipath->fspath->val[i].
1799 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1800 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1801 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1802 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1803 * have been needed to return all paths.
1804 */
1805int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1806{
1807	return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1808			     inode_to_path, ipath);
1809}
1810
1811struct btrfs_data_container *init_data_container(u32 total_bytes)
1812{
1813	struct btrfs_data_container *data;
1814	size_t alloc_bytes;
1815
1816	alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1817	data = vmalloc(alloc_bytes);
1818	if (!data)
1819		return ERR_PTR(-ENOMEM);
1820
1821	if (total_bytes >= sizeof(*data)) {
1822		data->bytes_left = total_bytes - sizeof(*data);
1823		data->bytes_missing = 0;
1824	} else {
1825		data->bytes_missing = sizeof(*data) - total_bytes;
1826		data->bytes_left = 0;
1827	}
1828
1829	data->elem_cnt = 0;
1830	data->elem_missed = 0;
1831
1832	return data;
1833}
1834
1835/*
1836 * allocates space to return multiple file system paths for an inode.
1837 * total_bytes to allocate are passed, note that space usable for actual path
1838 * information will be total_bytes - sizeof(struct inode_fs_paths).
1839 * the returned pointer must be freed with free_ipath() in the end.
1840 */
1841struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1842					struct btrfs_path *path)
1843{
1844	struct inode_fs_paths *ifp;
1845	struct btrfs_data_container *fspath;
1846
1847	fspath = init_data_container(total_bytes);
1848	if (IS_ERR(fspath))
1849		return (void *)fspath;
1850
1851	ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1852	if (!ifp) {
1853		kfree(fspath);
1854		return ERR_PTR(-ENOMEM);
1855	}
1856
1857	ifp->btrfs_path = path;
1858	ifp->fspath = fspath;
1859	ifp->fs_root = fs_root;
1860
1861	return ifp;
1862}
1863
1864void free_ipath(struct inode_fs_paths *ipath)
1865{
1866	if (!ipath)
1867		return;
1868	vfree(ipath->fspath);
1869	kfree(ipath);
1870}