backref.c 36.9 KB
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/*
 * Copyright (C) 2011 STRATO.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include "ctree.h"
#include "disk-io.h"
#include "backref.h"
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#include "ulist.h"
#include "transaction.h"
#include "delayed-ref.h"
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#include "locking.h"
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/*
 * this structure records all encountered refs on the way up to the root
 */
struct __prelim_ref {
	struct list_head list;
	u64 root_id;
	struct btrfs_key key;
	int level;
	int count;
	u64 parent;
	u64 wanted_disk_byte;
};

static int __add_prelim_ref(struct list_head *head, u64 root_id,
			    struct btrfs_key *key, int level, u64 parent,
			    u64 wanted_disk_byte, int count)
{
	struct __prelim_ref *ref;

	/* in case we're adding delayed refs, we're holding the refs spinlock */
	ref = kmalloc(sizeof(*ref), GFP_ATOMIC);
	if (!ref)
		return -ENOMEM;

	ref->root_id = root_id;
	if (key)
		ref->key = *key;
	else
		memset(&ref->key, 0, sizeof(ref->key));

	ref->level = level;
	ref->count = count;
	ref->parent = parent;
	ref->wanted_disk_byte = wanted_disk_byte;
	list_add_tail(&ref->list, head);

	return 0;
}

static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
				struct ulist *parents,
				struct extent_buffer *eb, int level,
				u64 wanted_objectid, u64 wanted_disk_byte)
{
	int ret;
	int slot;
	struct btrfs_file_extent_item *fi;
	struct btrfs_key key;
	u64 disk_byte;

add_parent:
	ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
	if (ret < 0)
		return ret;

	if (level != 0)
		return 0;

	/*
	 * if the current leaf is full with EXTENT_DATA items, we must
	 * check the next one if that holds a reference as well.
	 * ref->count cannot be used to skip this check.
	 * repeat this until we don't find any additional EXTENT_DATA items.
	 */
	while (1) {
		ret = btrfs_next_leaf(root, path);
		if (ret < 0)
			return ret;
		if (ret)
			return 0;

		eb = path->nodes[0];
		for (slot = 0; slot < btrfs_header_nritems(eb); ++slot) {
			btrfs_item_key_to_cpu(eb, &key, slot);
			if (key.objectid != wanted_objectid ||
			    key.type != BTRFS_EXTENT_DATA_KEY)
				return 0;
			fi = btrfs_item_ptr(eb, slot,
						struct btrfs_file_extent_item);
			disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
			if (disk_byte == wanted_disk_byte)
				goto add_parent;
		}
	}

	return 0;
}

/*
 * resolve an indirect backref in the form (root_id, key, level)
 * to a logical address
 */
static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
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					int search_commit_root,
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					struct __prelim_ref *ref,
					struct ulist *parents)
{
	struct btrfs_path *path;
	struct btrfs_root *root;
	struct btrfs_key root_key;
	struct btrfs_key key = {0};
	struct extent_buffer *eb;
	int ret = 0;
	int root_level;
	int level = ref->level;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;
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	path->search_commit_root = !!search_commit_root;
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	root_key.objectid = ref->root_id;
	root_key.type = BTRFS_ROOT_ITEM_KEY;
	root_key.offset = (u64)-1;
	root = btrfs_read_fs_root_no_name(fs_info, &root_key);
	if (IS_ERR(root)) {
		ret = PTR_ERR(root);
		goto out;
	}

	rcu_read_lock();
	root_level = btrfs_header_level(root->node);
	rcu_read_unlock();

	if (root_level + 1 == level)
		goto out;

	path->lowest_level = level;
	ret = btrfs_search_slot(NULL, root, &ref->key, path, 0, 0);
	pr_debug("search slot in root %llu (level %d, ref count %d) returned "
		 "%d for key (%llu %u %llu)\n",
		 (unsigned long long)ref->root_id, level, ref->count, ret,
		 (unsigned long long)ref->key.objectid, ref->key.type,
		 (unsigned long long)ref->key.offset);
	if (ret < 0)
		goto out;

	eb = path->nodes[level];
	if (!eb) {
		WARN_ON(1);
		ret = 1;
		goto out;
	}

	if (level == 0) {
		if (ret == 1 && path->slots[0] >= btrfs_header_nritems(eb)) {
			ret = btrfs_next_leaf(root, path);
			if (ret)
				goto out;
			eb = path->nodes[0];
		}

		btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
	}

	/* the last two parameters will only be used for level == 0 */
	ret = add_all_parents(root, path, parents, eb, level, key.objectid,
				ref->wanted_disk_byte);
out:
	btrfs_free_path(path);
	return ret;
}

/*
 * resolve all indirect backrefs from the list
 */
static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
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				   int search_commit_root,
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				   struct list_head *head)
{
	int err;
	int ret = 0;
	struct __prelim_ref *ref;
	struct __prelim_ref *ref_safe;
	struct __prelim_ref *new_ref;
	struct ulist *parents;
	struct ulist_node *node;
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	struct ulist_iterator uiter;
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	parents = ulist_alloc(GFP_NOFS);
	if (!parents)
		return -ENOMEM;

	/*
	 * _safe allows us to insert directly after the current item without
	 * iterating over the newly inserted items.
	 * we're also allowed to re-assign ref during iteration.
	 */
	list_for_each_entry_safe(ref, ref_safe, head, list) {
		if (ref->parent)	/* already direct */
			continue;
		if (ref->count == 0)
			continue;
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		err = __resolve_indirect_ref(fs_info, search_commit_root,
					     ref, parents);
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		if (err) {
			if (ret == 0)
				ret = err;
			continue;
		}

		/* we put the first parent into the ref at hand */
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		ULIST_ITER_INIT(&uiter);
		node = ulist_next(parents, &uiter);
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		ref->parent = node ? node->val : 0;

		/* additional parents require new refs being added here */
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		while ((node = ulist_next(parents, &uiter))) {
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			new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
			if (!new_ref) {
				ret = -ENOMEM;
				break;
			}
			memcpy(new_ref, ref, sizeof(*ref));
			new_ref->parent = node->val;
			list_add(&new_ref->list, &ref->list);
		}
		ulist_reinit(parents);
	}

	ulist_free(parents);
	return ret;
}

/*
 * merge two lists of backrefs and adjust counts accordingly
 *
 * mode = 1: merge identical keys, if key is set
 * mode = 2: merge identical parents
 */
static int __merge_refs(struct list_head *head, int mode)
{
	struct list_head *pos1;

	list_for_each(pos1, head) {
		struct list_head *n2;
		struct list_head *pos2;
		struct __prelim_ref *ref1;

		ref1 = list_entry(pos1, struct __prelim_ref, list);

		if (mode == 1 && ref1->key.type == 0)
			continue;
		for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
		     pos2 = n2, n2 = pos2->next) {
			struct __prelim_ref *ref2;

			ref2 = list_entry(pos2, struct __prelim_ref, list);

			if (mode == 1) {
				if (memcmp(&ref1->key, &ref2->key,
					   sizeof(ref1->key)) ||
				    ref1->level != ref2->level ||
				    ref1->root_id != ref2->root_id)
					continue;
				ref1->count += ref2->count;
			} else {
				if (ref1->parent != ref2->parent)
					continue;
				ref1->count += ref2->count;
			}
			list_del(&ref2->list);
			kfree(ref2);
		}

	}
	return 0;
}

/*
 * add all currently queued delayed refs from this head whose seq nr is
 * smaller or equal that seq to the list
 */
static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
			      struct btrfs_key *info_key,
			      struct list_head *prefs)
{
	struct btrfs_delayed_extent_op *extent_op = head->extent_op;
	struct rb_node *n = &head->node.rb_node;
	int sgn;
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	int ret = 0;
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	if (extent_op && extent_op->update_key)
		btrfs_disk_key_to_cpu(info_key, &extent_op->key);

	while ((n = rb_prev(n))) {
		struct btrfs_delayed_ref_node *node;
		node = rb_entry(n, struct btrfs_delayed_ref_node,
				rb_node);
		if (node->bytenr != head->node.bytenr)
			break;
		WARN_ON(node->is_head);

		if (node->seq > seq)
			continue;

		switch (node->action) {
		case BTRFS_ADD_DELAYED_EXTENT:
		case BTRFS_UPDATE_DELAYED_HEAD:
			WARN_ON(1);
			continue;
		case BTRFS_ADD_DELAYED_REF:
			sgn = 1;
			break;
		case BTRFS_DROP_DELAYED_REF:
			sgn = -1;
			break;
		default:
			BUG_ON(1);
		}
		switch (node->type) {
		case BTRFS_TREE_BLOCK_REF_KEY: {
			struct btrfs_delayed_tree_ref *ref;

			ref = btrfs_delayed_node_to_tree_ref(node);
			ret = __add_prelim_ref(prefs, ref->root, info_key,
					       ref->level + 1, 0, node->bytenr,
					       node->ref_mod * sgn);
			break;
		}
		case BTRFS_SHARED_BLOCK_REF_KEY: {
			struct btrfs_delayed_tree_ref *ref;

			ref = btrfs_delayed_node_to_tree_ref(node);
			ret = __add_prelim_ref(prefs, ref->root, info_key,
					       ref->level + 1, ref->parent,
					       node->bytenr,
					       node->ref_mod * sgn);
			break;
		}
		case BTRFS_EXTENT_DATA_REF_KEY: {
			struct btrfs_delayed_data_ref *ref;
			struct btrfs_key key;

			ref = btrfs_delayed_node_to_data_ref(node);

			key.objectid = ref->objectid;
			key.type = BTRFS_EXTENT_DATA_KEY;
			key.offset = ref->offset;
			ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
					       node->bytenr,
					       node->ref_mod * sgn);
			break;
		}
		case BTRFS_SHARED_DATA_REF_KEY: {
			struct btrfs_delayed_data_ref *ref;
			struct btrfs_key key;

			ref = btrfs_delayed_node_to_data_ref(node);

			key.objectid = ref->objectid;
			key.type = BTRFS_EXTENT_DATA_KEY;
			key.offset = ref->offset;
			ret = __add_prelim_ref(prefs, ref->root, &key, 0,
					       ref->parent, node->bytenr,
					       node->ref_mod * sgn);
			break;
		}
		default:
			WARN_ON(1);
		}
		BUG_ON(ret);
	}

	return 0;
}

/*
 * add all inline backrefs for bytenr to the list
 */
static int __add_inline_refs(struct btrfs_fs_info *fs_info,
			     struct btrfs_path *path, u64 bytenr,
			     struct btrfs_key *info_key, int *info_level,
			     struct list_head *prefs)
{
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	int ret = 0;
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	int slot;
	struct extent_buffer *leaf;
	struct btrfs_key key;
	unsigned long ptr;
	unsigned long end;
	struct btrfs_extent_item *ei;
	u64 flags;
	u64 item_size;

	/*
	 * enumerate all inline refs
	 */
	leaf = path->nodes[0];
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	slot = path->slots[0];
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	item_size = btrfs_item_size_nr(leaf, slot);
	BUG_ON(item_size < sizeof(*ei));

	ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
	flags = btrfs_extent_flags(leaf, ei);

	ptr = (unsigned long)(ei + 1);
	end = (unsigned long)ei + item_size;

	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
		struct btrfs_tree_block_info *info;
		struct btrfs_disk_key disk_key;

		info = (struct btrfs_tree_block_info *)ptr;
		*info_level = btrfs_tree_block_level(leaf, info);
		btrfs_tree_block_key(leaf, info, &disk_key);
		btrfs_disk_key_to_cpu(info_key, &disk_key);
		ptr += sizeof(struct btrfs_tree_block_info);
		BUG_ON(ptr > end);
	} else {
		BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
	}

	while (ptr < end) {
		struct btrfs_extent_inline_ref *iref;
		u64 offset;
		int type;

		iref = (struct btrfs_extent_inline_ref *)ptr;
		type = btrfs_extent_inline_ref_type(leaf, iref);
		offset = btrfs_extent_inline_ref_offset(leaf, iref);

		switch (type) {
		case BTRFS_SHARED_BLOCK_REF_KEY:
			ret = __add_prelim_ref(prefs, 0, info_key,
						*info_level + 1, offset,
						bytenr, 1);
			break;
		case BTRFS_SHARED_DATA_REF_KEY: {
			struct btrfs_shared_data_ref *sdref;
			int count;

			sdref = (struct btrfs_shared_data_ref *)(iref + 1);
			count = btrfs_shared_data_ref_count(leaf, sdref);
			ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
					       bytenr, count);
			break;
		}
		case BTRFS_TREE_BLOCK_REF_KEY:
			ret = __add_prelim_ref(prefs, offset, info_key,
					       *info_level + 1, 0, bytenr, 1);
			break;
		case BTRFS_EXTENT_DATA_REF_KEY: {
			struct btrfs_extent_data_ref *dref;
			int count;
			u64 root;

			dref = (struct btrfs_extent_data_ref *)(&iref->offset);
			count = btrfs_extent_data_ref_count(leaf, dref);
			key.objectid = btrfs_extent_data_ref_objectid(leaf,
								      dref);
			key.type = BTRFS_EXTENT_DATA_KEY;
			key.offset = btrfs_extent_data_ref_offset(leaf, dref);
			root = btrfs_extent_data_ref_root(leaf, dref);
			ret = __add_prelim_ref(prefs, root, &key, 0, 0, bytenr,
						count);
			break;
		}
		default:
			WARN_ON(1);
		}
		BUG_ON(ret);
		ptr += btrfs_extent_inline_ref_size(type);
	}

	return 0;
}

/*
 * add all non-inline backrefs for bytenr to the list
 */
static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
			    struct btrfs_path *path, u64 bytenr,
			    struct btrfs_key *info_key, int info_level,
			    struct list_head *prefs)
{
	struct btrfs_root *extent_root = fs_info->extent_root;
	int ret;
	int slot;
	struct extent_buffer *leaf;
	struct btrfs_key key;

	while (1) {
		ret = btrfs_next_item(extent_root, path);
		if (ret < 0)
			break;
		if (ret) {
			ret = 0;
			break;
		}

		slot = path->slots[0];
		leaf = path->nodes[0];
		btrfs_item_key_to_cpu(leaf, &key, slot);

		if (key.objectid != bytenr)
			break;
		if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
			continue;
		if (key.type > BTRFS_SHARED_DATA_REF_KEY)
			break;

		switch (key.type) {
		case BTRFS_SHARED_BLOCK_REF_KEY:
			ret = __add_prelim_ref(prefs, 0, info_key,
						info_level + 1, key.offset,
						bytenr, 1);
			break;
		case BTRFS_SHARED_DATA_REF_KEY: {
			struct btrfs_shared_data_ref *sdref;
			int count;

			sdref = btrfs_item_ptr(leaf, slot,
					      struct btrfs_shared_data_ref);
			count = btrfs_shared_data_ref_count(leaf, sdref);
			ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
						bytenr, count);
			break;
		}
		case BTRFS_TREE_BLOCK_REF_KEY:
			ret = __add_prelim_ref(prefs, key.offset, info_key,
						info_level + 1, 0, bytenr, 1);
			break;
		case BTRFS_EXTENT_DATA_REF_KEY: {
			struct btrfs_extent_data_ref *dref;
			int count;
			u64 root;

			dref = btrfs_item_ptr(leaf, slot,
					      struct btrfs_extent_data_ref);
			count = btrfs_extent_data_ref_count(leaf, dref);
			key.objectid = btrfs_extent_data_ref_objectid(leaf,
								      dref);
			key.type = BTRFS_EXTENT_DATA_KEY;
			key.offset = btrfs_extent_data_ref_offset(leaf, dref);
			root = btrfs_extent_data_ref_root(leaf, dref);
			ret = __add_prelim_ref(prefs, root, &key, 0, 0,
						bytenr, count);
			break;
		}
		default:
			WARN_ON(1);
		}
		BUG_ON(ret);
	}

	return ret;
}

/*
 * this adds all existing backrefs (inline backrefs, backrefs and delayed
 * refs) for the given bytenr to the refs list, merges duplicates and resolves
 * indirect refs to their parent bytenr.
 * When roots are found, they're added to the roots list
 *
 * FIXME some caching might speed things up
 */
static int find_parent_nodes(struct btrfs_trans_handle *trans,
			     struct btrfs_fs_info *fs_info, u64 bytenr,
			     u64 seq, struct ulist *refs, struct ulist *roots)
{
	struct btrfs_key key;
	struct btrfs_path *path;
	struct btrfs_key info_key = { 0 };
	struct btrfs_delayed_ref_root *delayed_refs = NULL;
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	struct btrfs_delayed_ref_head *head;
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	int info_level = 0;
	int ret;
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	int search_commit_root = (trans == BTRFS_BACKREF_SEARCH_COMMIT_ROOT);
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	struct list_head prefs_delayed;
	struct list_head prefs;
	struct __prelim_ref *ref;

	INIT_LIST_HEAD(&prefs);
	INIT_LIST_HEAD(&prefs_delayed);

	key.objectid = bytenr;
	key.type = BTRFS_EXTENT_ITEM_KEY;
	key.offset = (u64)-1;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;
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	path->search_commit_root = !!search_commit_root;
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	/*
	 * grab both a lock on the path and a lock on the delayed ref head.
	 * We need both to get a consistent picture of how the refs look
	 * at a specified point in time
	 */
again:
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	head = NULL;

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	ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
	if (ret < 0)
		goto out;
	BUG_ON(ret == 0);

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	if (trans != BTRFS_BACKREF_SEARCH_COMMIT_ROOT) {
		/*
		 * look if there are updates for this ref queued and lock the
		 * head
		 */
		delayed_refs = &trans->transaction->delayed_refs;
		spin_lock(&delayed_refs->lock);
		head = btrfs_find_delayed_ref_head(trans, bytenr);
		if (head) {
			if (!mutex_trylock(&head->mutex)) {
				atomic_inc(&head->node.refs);
				spin_unlock(&delayed_refs->lock);

				btrfs_release_path(path);

				/*
				 * Mutex was contended, block until it's
				 * released and try again
				 */
				mutex_lock(&head->mutex);
				mutex_unlock(&head->mutex);
				btrfs_put_delayed_ref(&head->node);
				goto again;
			}
			ret = __add_delayed_refs(head, seq, &info_key,
						 &prefs_delayed);
			if (ret) {
				spin_unlock(&delayed_refs->lock);
				goto out;
			}
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		}
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		spin_unlock(&delayed_refs->lock);
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	}

	if (path->slots[0]) {
		struct extent_buffer *leaf;
		int slot;

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		path->slots[0]--;
665
		leaf = path->nodes[0];
666
		slot = path->slots[0];
667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695
		btrfs_item_key_to_cpu(leaf, &key, slot);
		if (key.objectid == bytenr &&
		    key.type == BTRFS_EXTENT_ITEM_KEY) {
			ret = __add_inline_refs(fs_info, path, bytenr,
						&info_key, &info_level, &prefs);
			if (ret)
				goto out;
			ret = __add_keyed_refs(fs_info, path, bytenr, &info_key,
					       info_level, &prefs);
			if (ret)
				goto out;
		}
	}
	btrfs_release_path(path);

	/*
	 * when adding the delayed refs above, the info_key might not have
	 * been known yet. Go over the list and replace the missing keys
	 */
	list_for_each_entry(ref, &prefs_delayed, list) {
		if ((ref->key.offset | ref->key.type | ref->key.objectid) == 0)
			memcpy(&ref->key, &info_key, sizeof(ref->key));
	}
	list_splice_init(&prefs_delayed, &prefs);

	ret = __merge_refs(&prefs, 1);
	if (ret)
		goto out;

696
	ret = __resolve_indirect_refs(fs_info, search_commit_root, &prefs);
697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793
	if (ret)
		goto out;

	ret = __merge_refs(&prefs, 2);
	if (ret)
		goto out;

	while (!list_empty(&prefs)) {
		ref = list_first_entry(&prefs, struct __prelim_ref, list);
		list_del(&ref->list);
		if (ref->count < 0)
			WARN_ON(1);
		if (ref->count && ref->root_id && ref->parent == 0) {
			/* no parent == root of tree */
			ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
			BUG_ON(ret < 0);
		}
		if (ref->count && ref->parent) {
			ret = ulist_add(refs, ref->parent, 0, GFP_NOFS);
			BUG_ON(ret < 0);
		}
		kfree(ref);
	}

out:
	if (head)
		mutex_unlock(&head->mutex);
	btrfs_free_path(path);
	while (!list_empty(&prefs)) {
		ref = list_first_entry(&prefs, struct __prelim_ref, list);
		list_del(&ref->list);
		kfree(ref);
	}
	while (!list_empty(&prefs_delayed)) {
		ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
				       list);
		list_del(&ref->list);
		kfree(ref);
	}

	return ret;
}

/*
 * Finds all leafs with a reference to the specified combination of bytenr and
 * offset. key_list_head will point to a list of corresponding keys (caller must
 * free each list element). The leafs will be stored in the leafs ulist, which
 * must be freed with ulist_free.
 *
 * returns 0 on success, <0 on error
 */
static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
				struct btrfs_fs_info *fs_info, u64 bytenr,
				u64 num_bytes, u64 seq, struct ulist **leafs)
{
	struct ulist *tmp;
	int ret;

	tmp = ulist_alloc(GFP_NOFS);
	if (!tmp)
		return -ENOMEM;
	*leafs = ulist_alloc(GFP_NOFS);
	if (!*leafs) {
		ulist_free(tmp);
		return -ENOMEM;
	}

	ret = find_parent_nodes(trans, fs_info, bytenr, seq, *leafs, tmp);
	ulist_free(tmp);

	if (ret < 0 && ret != -ENOENT) {
		ulist_free(*leafs);
		return ret;
	}

	return 0;
}

/*
 * walk all backrefs for a given extent to find all roots that reference this
 * extent. Walking a backref means finding all extents that reference this
 * extent and in turn walk the backrefs of those, too. Naturally this is a
 * recursive process, but here it is implemented in an iterative fashion: We
 * find all referencing extents for the extent in question and put them on a
 * list. In turn, we find all referencing extents for those, further appending
 * to the list. The way we iterate the list allows adding more elements after
 * the current while iterating. The process stops when we reach the end of the
 * list. Found roots are added to the roots list.
 *
 * returns 0 on success, < 0 on error.
 */
int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
				struct btrfs_fs_info *fs_info, u64 bytenr,
				u64 num_bytes, u64 seq, struct ulist **roots)
{
	struct ulist *tmp;
	struct ulist_node *node = NULL;
J
Jan Schmidt 已提交
794
	struct ulist_iterator uiter;
795 796 797 798 799 800 801 802 803 804 805
	int ret;

	tmp = ulist_alloc(GFP_NOFS);
	if (!tmp)
		return -ENOMEM;
	*roots = ulist_alloc(GFP_NOFS);
	if (!*roots) {
		ulist_free(tmp);
		return -ENOMEM;
	}

J
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806
	ULIST_ITER_INIT(&uiter);
807 808 809 810 811 812 813 814
	while (1) {
		ret = find_parent_nodes(trans, fs_info, bytenr, seq,
					tmp, *roots);
		if (ret < 0 && ret != -ENOENT) {
			ulist_free(tmp);
			ulist_free(*roots);
			return ret;
		}
J
Jan Schmidt 已提交
815
		node = ulist_next(tmp, &uiter);
816 817 818 819 820 821 822 823 824 825
		if (!node)
			break;
		bytenr = node->val;
	}

	ulist_free(tmp);
	return 0;
}


826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901
static int __inode_info(u64 inum, u64 ioff, u8 key_type,
			struct btrfs_root *fs_root, struct btrfs_path *path,
			struct btrfs_key *found_key)
{
	int ret;
	struct btrfs_key key;
	struct extent_buffer *eb;

	key.type = key_type;
	key.objectid = inum;
	key.offset = ioff;

	ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
	if (ret < 0)
		return ret;

	eb = path->nodes[0];
	if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
		ret = btrfs_next_leaf(fs_root, path);
		if (ret)
			return ret;
		eb = path->nodes[0];
	}

	btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
	if (found_key->type != key.type || found_key->objectid != key.objectid)
		return 1;

	return 0;
}

/*
 * this makes the path point to (inum INODE_ITEM ioff)
 */
int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
			struct btrfs_path *path)
{
	struct btrfs_key key;
	return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path,
				&key);
}

static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
				struct btrfs_path *path,
				struct btrfs_key *found_key)
{
	return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path,
				found_key);
}

/*
 * this iterates to turn a btrfs_inode_ref into a full filesystem path. elements
 * of the path are separated by '/' and the path is guaranteed to be
 * 0-terminated. the path is only given within the current file system.
 * Therefore, it never starts with a '/'. the caller is responsible to provide
 * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
 * the start point of the resulting string is returned. this pointer is within
 * dest, normally.
 * in case the path buffer would overflow, the pointer is decremented further
 * as if output was written to the buffer, though no more output is actually
 * generated. that way, the caller can determine how much space would be
 * required for the path to fit into the buffer. in that case, the returned
 * value will be smaller than dest. callers must check this!
 */
static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
				struct btrfs_inode_ref *iref,
				struct extent_buffer *eb_in, u64 parent,
				char *dest, u32 size)
{
	u32 len;
	int slot;
	u64 next_inum;
	int ret;
	s64 bytes_left = size - 1;
	struct extent_buffer *eb = eb_in;
	struct btrfs_key found_key;
902
	int leave_spinning = path->leave_spinning;
903 904 905 906

	if (bytes_left >= 0)
		dest[bytes_left] = '\0';

907
	path->leave_spinning = 1;
908 909 910 911 912 913
	while (1) {
		len = btrfs_inode_ref_name_len(eb, iref);
		bytes_left -= len;
		if (bytes_left >= 0)
			read_extent_buffer(eb, dest + bytes_left,
						(unsigned long)(iref + 1), len);
914 915
		if (eb != eb_in) {
			btrfs_tree_read_unlock_blocking(eb);
916
			free_extent_buffer(eb);
917
		}
918
		ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
919 920
		if (ret > 0)
			ret = -ENOENT;
921 922 923 924 925 926 927 928 929 930 931
		if (ret)
			break;
		next_inum = found_key.offset;

		/* regular exit ahead */
		if (parent == next_inum)
			break;

		slot = path->slots[0];
		eb = path->nodes[0];
		/* make sure we can use eb after releasing the path */
932
		if (eb != eb_in) {
933
			atomic_inc(&eb->refs);
934 935 936
			btrfs_tree_read_lock(eb);
			btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
		}
937 938 939 940 941 942 943 944 945 946
		btrfs_release_path(path);

		iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
		parent = next_inum;
		--bytes_left;
		if (bytes_left >= 0)
			dest[bytes_left] = '/';
	}

	btrfs_release_path(path);
947
	path->leave_spinning = leave_spinning;
948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984

	if (ret)
		return ERR_PTR(ret);

	return dest + bytes_left;
}

/*
 * this makes the path point to (logical EXTENT_ITEM *)
 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
 * tree blocks and <0 on error.
 */
int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
			struct btrfs_path *path, struct btrfs_key *found_key)
{
	int ret;
	u64 flags;
	u32 item_size;
	struct extent_buffer *eb;
	struct btrfs_extent_item *ei;
	struct btrfs_key key;

	key.type = BTRFS_EXTENT_ITEM_KEY;
	key.objectid = logical;
	key.offset = (u64)-1;

	ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
	if (ret < 0)
		return ret;
	ret = btrfs_previous_item(fs_info->extent_root, path,
					0, BTRFS_EXTENT_ITEM_KEY);
	if (ret < 0)
		return ret;

	btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
	if (found_key->type != BTRFS_EXTENT_ITEM_KEY ||
	    found_key->objectid > logical ||
J
Jan Schmidt 已提交
985 986 987
	    found_key->objectid + found_key->offset <= logical) {
		pr_debug("logical %llu is not within any extent\n",
			 (unsigned long long)logical);
988
		return -ENOENT;
J
Jan Schmidt 已提交
989
	}
990 991 992 993 994 995 996 997

	eb = path->nodes[0];
	item_size = btrfs_item_size_nr(eb, path->slots[0]);
	BUG_ON(item_size < sizeof(*ei));

	ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
	flags = btrfs_extent_flags(eb, ei);

J
Jan Schmidt 已提交
998 999 1000 1001 1002 1003 1004
	pr_debug("logical %llu is at position %llu within the extent (%llu "
		 "EXTENT_ITEM %llu) flags %#llx size %u\n",
		 (unsigned long long)logical,
		 (unsigned long long)(logical - found_key->objectid),
		 (unsigned long long)found_key->objectid,
		 (unsigned long long)found_key->offset,
		 (unsigned long long)flags, item_size);
1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100
	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
		return BTRFS_EXTENT_FLAG_TREE_BLOCK;
	if (flags & BTRFS_EXTENT_FLAG_DATA)
		return BTRFS_EXTENT_FLAG_DATA;

	return -EIO;
}

/*
 * helper function to iterate extent inline refs. ptr must point to a 0 value
 * for the first call and may be modified. it is used to track state.
 * if more refs exist, 0 is returned and the next call to
 * __get_extent_inline_ref must pass the modified ptr parameter to get the
 * next ref. after the last ref was processed, 1 is returned.
 * returns <0 on error
 */
static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
				struct btrfs_extent_item *ei, u32 item_size,
				struct btrfs_extent_inline_ref **out_eiref,
				int *out_type)
{
	unsigned long end;
	u64 flags;
	struct btrfs_tree_block_info *info;

	if (!*ptr) {
		/* first call */
		flags = btrfs_extent_flags(eb, ei);
		if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
			info = (struct btrfs_tree_block_info *)(ei + 1);
			*out_eiref =
				(struct btrfs_extent_inline_ref *)(info + 1);
		} else {
			*out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
		}
		*ptr = (unsigned long)*out_eiref;
		if ((void *)*ptr >= (void *)ei + item_size)
			return -ENOENT;
	}

	end = (unsigned long)ei + item_size;
	*out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
	*out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);

	*ptr += btrfs_extent_inline_ref_size(*out_type);
	WARN_ON(*ptr > end);
	if (*ptr == end)
		return 1; /* last */

	return 0;
}

/*
 * reads the tree block backref for an extent. tree level and root are returned
 * through out_level and out_root. ptr must point to a 0 value for the first
 * call and may be modified (see __get_extent_inline_ref comment).
 * returns 0 if data was provided, 1 if there was no more data to provide or
 * <0 on error.
 */
int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
				struct btrfs_extent_item *ei, u32 item_size,
				u64 *out_root, u8 *out_level)
{
	int ret;
	int type;
	struct btrfs_tree_block_info *info;
	struct btrfs_extent_inline_ref *eiref;

	if (*ptr == (unsigned long)-1)
		return 1;

	while (1) {
		ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
						&eiref, &type);
		if (ret < 0)
			return ret;

		if (type == BTRFS_TREE_BLOCK_REF_KEY ||
		    type == BTRFS_SHARED_BLOCK_REF_KEY)
			break;

		if (ret == 1)
			return 1;
	}

	/* we can treat both ref types equally here */
	info = (struct btrfs_tree_block_info *)(ei + 1);
	*out_root = btrfs_extent_inline_ref_offset(eb, eiref);
	*out_level = btrfs_tree_block_level(eb, info);

	if (ret == 1)
		*ptr = (unsigned long)-1;

	return 0;
}

1101
static int iterate_leaf_refs(struct btrfs_fs_info *fs_info, u64 logical,
J
Jan Schmidt 已提交
1102 1103 1104
				u64 orig_extent_item_objectid,
				u64 extent_item_pos, u64 root,
				iterate_extent_inodes_t *iterate, void *ctx)
1105 1106 1107 1108 1109 1110 1111
{
	u64 disk_byte;
	struct btrfs_key key;
	struct btrfs_file_extent_item *fi;
	struct extent_buffer *eb;
	int slot;
	int nritems;
J
Jan Schmidt 已提交
1112 1113 1114 1115
	int ret = 0;
	int extent_type;
	u64 data_offset;
	u64 data_len;
1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132

	eb = read_tree_block(fs_info->tree_root, logical,
				fs_info->tree_root->leafsize, 0);
	if (!eb)
		return -EIO;

	/*
	 * from the shared data ref, we only have the leaf but we need
	 * the key. thus, we must look into all items and see that we
	 * find one (some) with a reference to our extent item.
	 */
	nritems = btrfs_header_nritems(eb);
	for (slot = 0; slot < nritems; ++slot) {
		btrfs_item_key_to_cpu(eb, &key, slot);
		if (key.type != BTRFS_EXTENT_DATA_KEY)
			continue;
		fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
J
Jan Schmidt 已提交
1133 1134 1135 1136
		extent_type = btrfs_file_extent_type(eb, fi);
		if (extent_type == BTRFS_FILE_EXTENT_INLINE)
			continue;
		/* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
1137
		disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
J
Jan Schmidt 已提交
1138 1139
		if (disk_byte != orig_extent_item_objectid)
			continue;
1140

J
Jan Schmidt 已提交
1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157
		data_offset = btrfs_file_extent_offset(eb, fi);
		data_len = btrfs_file_extent_num_bytes(eb, fi);

		if (extent_item_pos < data_offset ||
		    extent_item_pos >= data_offset + data_len)
			continue;

		pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
				"root %llu\n", orig_extent_item_objectid,
				key.objectid, key.offset, root);
		ret = iterate(key.objectid,
				key.offset + (extent_item_pos - data_offset),
				root, ctx);
		if (ret) {
			pr_debug("stopping iteration because ret=%d\n", ret);
			break;
		}
1158 1159 1160
	}

	free_extent_buffer(eb);
J
Jan Schmidt 已提交
1161

1162 1163 1164 1165 1166
	return ret;
}

/*
 * calls iterate() for every inode that references the extent identified by
J
Jan Schmidt 已提交
1167
 * the given parameters.
1168 1169 1170
 * when the iterator function returns a non-zero value, iteration stops.
 */
int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
J
Jan Schmidt 已提交
1171
				u64 extent_item_objectid, u64 extent_item_pos,
1172
				int search_commit_root,
1173 1174 1175 1176 1177
				iterate_extent_inodes_t *iterate, void *ctx)
{
	int ret;
	struct list_head data_refs = LIST_HEAD_INIT(data_refs);
	struct list_head shared_refs = LIST_HEAD_INIT(shared_refs);
J
Jan Schmidt 已提交
1178
	struct btrfs_trans_handle *trans;
1179 1180
	struct ulist *refs = NULL;
	struct ulist *roots = NULL;
J
Jan Schmidt 已提交
1181 1182 1183
	struct ulist_node *ref_node = NULL;
	struct ulist_node *root_node = NULL;
	struct seq_list seq_elem;
J
Jan Schmidt 已提交
1184 1185
	struct ulist_iterator ref_uiter;
	struct ulist_iterator root_uiter;
1186
	struct btrfs_delayed_ref_root *delayed_refs = NULL;
1187

J
Jan Schmidt 已提交
1188 1189
	pr_debug("resolving all inodes for extent %llu\n",
			extent_item_objectid);
1190

1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202
	if (search_commit_root) {
		trans = BTRFS_BACKREF_SEARCH_COMMIT_ROOT;
	} else {
		trans = btrfs_join_transaction(fs_info->extent_root);
		if (IS_ERR(trans))
			return PTR_ERR(trans);

		delayed_refs = &trans->transaction->delayed_refs;
		spin_lock(&delayed_refs->lock);
		btrfs_get_delayed_seq(delayed_refs, &seq_elem);
		spin_unlock(&delayed_refs->lock);
	}
1203

J
Jan Schmidt 已提交
1204 1205 1206
	ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
				   extent_item_pos, seq_elem.seq,
				   &refs);
1207

J
Jan Schmidt 已提交
1208 1209
	if (ret)
		goto out;
1210

J
Jan Schmidt 已提交
1211 1212
	ULIST_ITER_INIT(&ref_uiter);
	while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
J
Jan Schmidt 已提交
1213 1214 1215 1216
		ret = btrfs_find_all_roots(trans, fs_info, ref_node->val, -1,
						seq_elem.seq, &roots);
		if (ret)
			break;
J
Jan Schmidt 已提交
1217 1218
		ULIST_ITER_INIT(&root_uiter);
		while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
J
Jan Schmidt 已提交
1219 1220
			pr_debug("root %llu references leaf %llu\n",
					root_node->val, ref_node->val);
1221
			ret = iterate_leaf_refs(fs_info, ref_node->val,
J
Jan Schmidt 已提交
1222 1223 1224 1225
						extent_item_objectid,
						extent_item_pos, root_node->val,
						iterate, ctx);
		}
1226 1227
	}

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Jan Schmidt 已提交
1228 1229 1230
	ulist_free(refs);
	ulist_free(roots);
out:
1231 1232 1233 1234 1235
	if (!search_commit_root) {
		btrfs_put_delayed_seq(delayed_refs, &seq_elem);
		btrfs_end_transaction(trans, fs_info->extent_root);
	}

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	return ret;
}

int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
				struct btrfs_path *path,
				iterate_extent_inodes_t *iterate, void *ctx)
{
	int ret;
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	u64 extent_item_pos;
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	struct btrfs_key found_key;
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	int search_commit_root = path->search_commit_root;
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	ret = extent_from_logical(fs_info, logical, path,
					&found_key);
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	btrfs_release_path(path);
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	if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
		ret = -EINVAL;
	if (ret < 0)
		return ret;

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	extent_item_pos = logical - found_key.objectid;
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	ret = iterate_extent_inodes(fs_info, found_key.objectid,
					extent_item_pos, search_commit_root,
					iterate, ctx);
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	return ret;
}

static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
				struct btrfs_path *path,
				iterate_irefs_t *iterate, void *ctx)
{
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	int ret = 0;
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	int slot;
	u32 cur;
	u32 len;
	u32 name_len;
	u64 parent = 0;
	int found = 0;
	struct extent_buffer *eb;
	struct btrfs_item *item;
	struct btrfs_inode_ref *iref;
	struct btrfs_key found_key;

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	while (!ret) {
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		path->leave_spinning = 1;
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		ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
					&found_key);
		if (ret < 0)
			break;
		if (ret) {
			ret = found ? 0 : -ENOENT;
			break;
		}
		++found;

		parent = found_key.offset;
		slot = path->slots[0];
		eb = path->nodes[0];
		/* make sure we can use eb after releasing the path */
		atomic_inc(&eb->refs);
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		btrfs_tree_read_lock(eb);
		btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
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		btrfs_release_path(path);

		item = btrfs_item_nr(eb, slot);
		iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);

		for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
			name_len = btrfs_inode_ref_name_len(eb, iref);
			/* path must be released before calling iterate()! */
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			pr_debug("following ref at offset %u for inode %llu in "
				 "tree %llu\n", cur,
				 (unsigned long long)found_key.objectid,
				 (unsigned long long)fs_root->objectid);
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			ret = iterate(parent, iref, eb, ctx);
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			if (ret)
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				break;
			len = sizeof(*iref) + name_len;
			iref = (struct btrfs_inode_ref *)((char *)iref + len);
		}
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		btrfs_tree_read_unlock_blocking(eb);
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		free_extent_buffer(eb);
	}

	btrfs_release_path(path);

	return ret;
}

/*
 * returns 0 if the path could be dumped (probably truncated)
 * returns <0 in case of an error
 */
static int inode_to_path(u64 inum, struct btrfs_inode_ref *iref,
				struct extent_buffer *eb, void *ctx)
{
	struct inode_fs_paths *ipath = ctx;
	char *fspath;
	char *fspath_min;
	int i = ipath->fspath->elem_cnt;
	const int s_ptr = sizeof(char *);
	u32 bytes_left;

	bytes_left = ipath->fspath->bytes_left > s_ptr ?
					ipath->fspath->bytes_left - s_ptr : 0;

1343
	fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
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	fspath = iref_to_path(ipath->fs_root, ipath->btrfs_path, iref, eb,
				inum, fspath_min, bytes_left);
	if (IS_ERR(fspath))
		return PTR_ERR(fspath);

	if (fspath > fspath_min) {
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		pr_debug("path resolved: %s\n", fspath);
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		ipath->fspath->val[i] = (u64)(unsigned long)fspath;
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		++ipath->fspath->elem_cnt;
		ipath->fspath->bytes_left = fspath - fspath_min;
	} else {
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		pr_debug("missed path, not enough space. missing bytes: %lu, "
			 "constructed so far: %s\n",
			 (unsigned long)(fspath_min - fspath), fspath_min);
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		++ipath->fspath->elem_missed;
		ipath->fspath->bytes_missing += fspath_min - fspath;
		ipath->fspath->bytes_left = 0;
	}

	return 0;
}

/*
 * this dumps all file system paths to the inode into the ipath struct, provided
 * is has been created large enough. each path is zero-terminated and accessed
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 * from ipath->fspath->val[i].
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 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1371
 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
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 * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
 * have been needed to return all paths.
 */
int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
{
	return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
				inode_to_path, ipath);
}

struct btrfs_data_container *init_data_container(u32 total_bytes)
{
	struct btrfs_data_container *data;
	size_t alloc_bytes;

	alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
	data = kmalloc(alloc_bytes, GFP_NOFS);
	if (!data)
		return ERR_PTR(-ENOMEM);

	if (total_bytes >= sizeof(*data)) {
		data->bytes_left = total_bytes - sizeof(*data);
		data->bytes_missing = 0;
	} else {
		data->bytes_missing = sizeof(*data) - total_bytes;
		data->bytes_left = 0;
	}

	data->elem_cnt = 0;
	data->elem_missed = 0;

	return data;
}

/*
 * allocates space to return multiple file system paths for an inode.
 * total_bytes to allocate are passed, note that space usable for actual path
 * information will be total_bytes - sizeof(struct inode_fs_paths).
 * the returned pointer must be freed with free_ipath() in the end.
 */
struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
					struct btrfs_path *path)
{
	struct inode_fs_paths *ifp;
	struct btrfs_data_container *fspath;

	fspath = init_data_container(total_bytes);
	if (IS_ERR(fspath))
		return (void *)fspath;

	ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
	if (!ifp) {
		kfree(fspath);
		return ERR_PTR(-ENOMEM);
	}

	ifp->btrfs_path = path;
	ifp->fspath = fspath;
	ifp->fs_root = fs_root;

	return ifp;
}

void free_ipath(struct inode_fs_paths *ipath)
{
1437 1438
	if (!ipath)
		return;
1439
	kfree(ipath->fspath);
1440 1441
	kfree(ipath);
}