backref.c 42.2 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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struct extent_inode_elem {
	u64 inum;
	u64 offset;
	struct extent_inode_elem *next;
};

static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
				struct btrfs_file_extent_item *fi,
				u64 extent_item_pos,
				struct extent_inode_elem **eie)
{
	u64 data_offset;
	u64 data_len;
	struct extent_inode_elem *e;

	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)
		return 1;

	e = kmalloc(sizeof(*e), GFP_NOFS);
	if (!e)
		return -ENOMEM;

	e->next = *eie;
	e->inum = key->objectid;
	e->offset = key->offset + (extent_item_pos - data_offset);
	*eie = e;

	return 0;
}

static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
				u64 extent_item_pos,
				struct extent_inode_elem **eie)
{
	u64 disk_byte;
	struct btrfs_key key;
	struct btrfs_file_extent_item *fi;
	int slot;
	int nritems;
	int extent_type;
	int ret;

	/*
	 * 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);
		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 */
		disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
		if (disk_byte != wanted_disk_byte)
			continue;

		ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
		if (ret < 0)
			return ret;
	}

	return 0;
}

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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;
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	struct btrfs_key key_for_search;
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	int level;
	int count;
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	struct extent_inode_elem *inode_list;
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	u64 parent;
	u64 wanted_disk_byte;
};

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/*
 * the rules for all callers of this function are:
 * - obtaining the parent is the goal
 * - if you add a key, you must know that it is a correct key
 * - if you cannot add the parent or a correct key, then we will look into the
 *   block later to set a correct key
 *
 * delayed refs
 * ============
 *        backref type | shared | indirect | shared | indirect
 * information         |   tree |     tree |   data |     data
 * --------------------+--------+----------+--------+----------
 *      parent logical |    y   |     -    |    -   |     -
 *      key to resolve |    -   |     y    |    y   |     y
 *  tree block logical |    -   |     -    |    -   |     -
 *  root for resolving |    y   |     y    |    y   |     y
 *
 * - column 1:       we've the parent -> done
 * - column 2, 3, 4: we use the key to find the parent
 *
 * on disk refs (inline or keyed)
 * ==============================
 *        backref type | shared | indirect | shared | indirect
 * information         |   tree |     tree |   data |     data
 * --------------------+--------+----------+--------+----------
 *      parent logical |    y   |     -    |    y   |     -
 *      key to resolve |    -   |     -    |    -   |     y
 *  tree block logical |    y   |     y    |    y   |     y
 *  root for resolving |    -   |     y    |    y   |     y
 *
 * - column 1, 3: we've the parent -> done
 * - column 2:    we take the first key from the block to find the parent
 *                (see __add_missing_keys)
 * - column 4:    we use the key to find the parent
 *
 * additional information that's available but not required to find the parent
 * block might help in merging entries to gain some speed.
 */

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static int __add_prelim_ref(struct list_head *head, u64 root_id,
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			    struct btrfs_key *key, int level,
			    u64 parent, u64 wanted_disk_byte, int count)
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{
	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)
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		ref->key_for_search = *key;
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	else
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		memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
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	ref->inode_list = NULL;
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	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,
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				struct ulist *parents, int level,
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				struct btrfs_key *key_for_search, u64 time_seq,
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				u64 wanted_disk_byte,
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				const u64 *extent_item_pos)
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{
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	int ret = 0;
	int slot;
	struct extent_buffer *eb;
	struct btrfs_key key;
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	struct btrfs_file_extent_item *fi;
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	struct extent_inode_elem *eie = NULL;
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	u64 disk_byte;

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	if (level != 0) {
		eb = path->nodes[level];
		ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
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		if (ret < 0)
			return ret;
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		return 0;
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	}
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	/*
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	 * We normally enter this function with the path already pointing to
	 * the first item to check. But sometimes, we may enter it with
	 * slot==nritems. In that case, go to the next leaf before we continue.
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	 */
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	if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
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		ret = btrfs_next_old_leaf(root, path, time_seq);
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	while (!ret) {
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		eb = path->nodes[0];
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		slot = path->slots[0];

		btrfs_item_key_to_cpu(eb, &key, slot);

		if (key.objectid != key_for_search->objectid ||
		    key.type != BTRFS_EXTENT_DATA_KEY)
			break;

		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) {
			eie = NULL;
			if (extent_item_pos) {
				ret = check_extent_in_eb(&key, eb, fi,
						*extent_item_pos,
						&eie);
				if (ret < 0)
					break;
			}
			if (!ret) {
				ret = ulist_add(parents, eb->start,
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						(uintptr_t)eie, GFP_NOFS);
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				if (ret < 0)
					break;
				if (!extent_item_pos) {
					ret = btrfs_next_old_leaf(root, path,
							time_seq);
					continue;
				}
			}
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		}
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		ret = btrfs_next_old_item(root, path, time_seq);
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	}

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	if (ret > 0)
		ret = 0;
	return ret;
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}

/*
 * 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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					u64 time_seq,
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					struct __prelim_ref *ref,
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					struct ulist *parents,
					const u64 *extent_item_pos)
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{
	struct btrfs_path *path;
	struct btrfs_root *root;
	struct btrfs_key root_key;
	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;
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	ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
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	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,
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		 (unsigned long long)ref->key_for_search.objectid,
		 ref->key_for_search.type,
		 (unsigned long long)ref->key_for_search.offset);
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	if (ret < 0)
		goto out;

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

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	ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
				time_seq, ref->wanted_disk_byte,
				extent_item_pos);
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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, u64 time_seq,
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				   struct list_head *head,
				   const u64 *extent_item_pos)
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{
	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,
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					     time_seq, ref, parents,
					     extent_item_pos);
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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;
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		ref->inode_list = node ?
			(struct extent_inode_elem *)(uintptr_t)node->aux : 0;
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		/* 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;
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			new_ref->inode_list = (struct extent_inode_elem *)
							(uintptr_t)node->aux;
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			list_add(&new_ref->list, &ref->list);
		}
		ulist_reinit(parents);
	}

	ulist_free(parents);
	return ret;
}

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static inline int ref_for_same_block(struct __prelim_ref *ref1,
				     struct __prelim_ref *ref2)
{
	if (ref1->level != ref2->level)
		return 0;
	if (ref1->root_id != ref2->root_id)
		return 0;
	if (ref1->key_for_search.type != ref2->key_for_search.type)
		return 0;
	if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
		return 0;
	if (ref1->key_for_search.offset != ref2->key_for_search.offset)
		return 0;
	if (ref1->parent != ref2->parent)
		return 0;

	return 1;
}

/*
 * read tree blocks and add keys where required.
 */
static int __add_missing_keys(struct btrfs_fs_info *fs_info,
			      struct list_head *head)
{
	struct list_head *pos;
	struct extent_buffer *eb;

	list_for_each(pos, head) {
		struct __prelim_ref *ref;
		ref = list_entry(pos, struct __prelim_ref, list);

		if (ref->parent)
			continue;
		if (ref->key_for_search.type)
			continue;
		BUG_ON(!ref->wanted_disk_byte);
		eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
				     fs_info->tree_root->leafsize, 0);
		BUG_ON(!eb);
		btrfs_tree_read_lock(eb);
		if (btrfs_header_level(eb) == 0)
			btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
		else
			btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
		btrfs_tree_read_unlock(eb);
		free_extent_buffer(eb);
	}
	return 0;
}

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/*
 * merge two lists of backrefs and adjust counts accordingly
 *
 * mode = 1: merge identical keys, if key is set
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 *    FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
 *           additionally, we could even add a key range for the blocks we
 *           looked into to merge even more (-> replace unresolved refs by those
 *           having a parent).
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 * 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);

		for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
		     pos2 = n2, n2 = pos2->next) {
			struct __prelim_ref *ref2;
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			struct __prelim_ref *xchg;
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			ref2 = list_entry(pos2, struct __prelim_ref, list);

			if (mode == 1) {
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				if (!ref_for_same_block(ref1, ref2))
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					continue;
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				if (!ref1->parent && ref2->parent) {
					xchg = ref1;
					ref1 = ref2;
					ref2 = xchg;
				}
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				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 list_head *prefs)
{
	struct btrfs_delayed_extent_op *extent_op = head->extent_op;
	struct rb_node *n = &head->node.rb_node;
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	struct btrfs_key key;
	struct btrfs_key op_key = {0};
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	int sgn;
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	int ret = 0;
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	if (extent_op && extent_op->update_key)
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		btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
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	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);
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			ret = __add_prelim_ref(prefs, ref->root, &op_key,
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					       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);
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			ret = __add_prelim_ref(prefs, ref->root, NULL,
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					       ref->level + 1, ref->parent,
					       node->bytenr,
					       node->ref_mod * sgn);
			break;
		}
		case BTRFS_EXTENT_DATA_REF_KEY: {
			struct btrfs_delayed_data_ref *ref;
			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;

			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,
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			     int *info_level, struct list_head *prefs)
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{
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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;

		info = (struct btrfs_tree_block_info *)ptr;
		*info_level = btrfs_tree_block_level(leaf, info);
		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:
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			ret = __add_prelim_ref(prefs, 0, NULL,
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						*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:
655 656 657
			ret = __add_prelim_ref(prefs, offset, NULL,
					       *info_level + 1, 0,
					       bytenr, 1);
658 659 660 661 662 663 664 665 666 667 668 669 670
			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);
671 672
			ret = __add_prelim_ref(prefs, root, &key, 0, 0,
					       bytenr, count);
673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689
			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,
690
			    int info_level, struct list_head *prefs)
691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719
{
	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:
720
			ret = __add_prelim_ref(prefs, 0, NULL,
721 722 723 724 725 726 727 728 729 730 731 732 733 734 735
						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:
736 737 738
			ret = __add_prelim_ref(prefs, key.offset, NULL,
					       info_level + 1, 0,
					       bytenr, 1);
739 740 741 742 743 744 745 746 747 748 749 750 751 752 753
			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,
754
					       bytenr, count);
755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775
			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,
776 777
			     u64 time_seq, struct ulist *refs,
			     struct ulist *roots, const u64 *extent_item_pos)
778 779 780 781
{
	struct btrfs_key key;
	struct btrfs_path *path;
	struct btrfs_delayed_ref_root *delayed_refs = NULL;
782
	struct btrfs_delayed_ref_head *head;
783 784
	int info_level = 0;
	int ret;
785
	int search_commit_root = (trans == BTRFS_BACKREF_SEARCH_COMMIT_ROOT);
786 787 788 789 790 791 792 793 794 795 796 797 798 799
	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;
800
	path->search_commit_root = !!search_commit_root;
801 802 803 804 805 806 807

	/*
	 * 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:
808 809
	head = NULL;

810 811 812 813 814
	ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
	if (ret < 0)
		goto out;
	BUG_ON(ret == 0);

815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838
	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;
			}
839
			ret = __add_delayed_refs(head, time_seq,
840
						 &prefs_delayed);
841
			mutex_unlock(&head->mutex);
842 843 844 845
			if (ret) {
				spin_unlock(&delayed_refs->lock);
				goto out;
			}
846
		}
847
		spin_unlock(&delayed_refs->lock);
848 849 850 851 852 853
	}

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

854
		path->slots[0]--;
855
		leaf = path->nodes[0];
856
		slot = path->slots[0];
857 858 859 860
		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,
861
						&info_level, &prefs);
862 863
			if (ret)
				goto out;
864
			ret = __add_keyed_refs(fs_info, path, bytenr,
865 866 867 868 869 870 871 872 873
					       info_level, &prefs);
			if (ret)
				goto out;
		}
	}
	btrfs_release_path(path);

	list_splice_init(&prefs_delayed, &prefs);

874 875 876 877
	ret = __add_missing_keys(fs_info, &prefs);
	if (ret)
		goto out;

878 879 880 881
	ret = __merge_refs(&prefs, 1);
	if (ret)
		goto out;

882 883
	ret = __resolve_indirect_refs(fs_info, search_commit_root, time_seq,
				      &prefs, extent_item_pos);
884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901
	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) {
902
			struct extent_inode_elem *eie = NULL;
903
			if (extent_item_pos && !ref->inode_list) {
904 905 906 907 908 909 910 911 912
				u32 bsz;
				struct extent_buffer *eb;
				bsz = btrfs_level_size(fs_info->extent_root,
							info_level);
				eb = read_tree_block(fs_info->extent_root,
							   ref->parent, bsz, 0);
				BUG_ON(!eb);
				ret = find_extent_in_eb(eb, bytenr,
							*extent_item_pos, &eie);
913
				ref->inode_list = eie;
914 915
				free_extent_buffer(eb);
			}
916
			ret = ulist_add_merge(refs, ref->parent,
917
					      (uintptr_t)ref->inode_list,
918
					      (u64 *)&eie, GFP_NOFS);
919 920 921 922 923 924 925 926 927 928
			if (!ret && extent_item_pos) {
				/*
				 * we've recorded that parent, so we must extend
				 * its inode list here
				 */
				BUG_ON(!eie);
				while (eie->next)
					eie = eie->next;
				eie->next = ref->inode_list;
			}
929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950
			BUG_ON(ret < 0);
		}
		kfree(ref);
	}

out:
	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;
}

951 952 953 954 955 956 957 958 959 960 961
static void free_leaf_list(struct ulist *blocks)
{
	struct ulist_node *node = NULL;
	struct extent_inode_elem *eie;
	struct extent_inode_elem *eie_next;
	struct ulist_iterator uiter;

	ULIST_ITER_INIT(&uiter);
	while ((node = ulist_next(blocks, &uiter))) {
		if (!node->aux)
			continue;
962
		eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
963 964 965 966 967 968 969 970 971 972
		for (; eie; eie = eie_next) {
			eie_next = eie->next;
			kfree(eie);
		}
		node->aux = 0;
	}

	ulist_free(blocks);
}

973 974 975 976 977 978 979 980 981 982
/*
 * 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,
983
				u64 time_seq, struct ulist **leafs,
984
				const u64 *extent_item_pos)
985 986 987 988 989 990 991 992 993 994 995 996 997
{
	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;
	}

998
	ret = find_parent_nodes(trans, fs_info, bytenr,
999
				time_seq, *leafs, tmp, extent_item_pos);
1000 1001 1002
	ulist_free(tmp);

	if (ret < 0 && ret != -ENOENT) {
1003
		free_leaf_list(*leafs);
1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024
		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,
1025
				u64 time_seq, struct ulist **roots)
1026 1027 1028
{
	struct ulist *tmp;
	struct ulist_node *node = NULL;
J
Jan Schmidt 已提交
1029
	struct ulist_iterator uiter;
1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
	int ret;

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

J
Jan Schmidt 已提交
1041
	ULIST_ITER_INIT(&uiter);
1042
	while (1) {
1043
		ret = find_parent_nodes(trans, fs_info, bytenr,
1044
					time_seq, tmp, *roots, NULL);
1045 1046 1047 1048 1049
		if (ret < 0 && ret != -ENOENT) {
			ulist_free(tmp);
			ulist_free(*roots);
			return ret;
		}
J
Jan Schmidt 已提交
1050
		node = ulist_next(tmp, &uiter);
1051 1052 1053 1054 1055 1056 1057 1058 1059 1060
		if (!node)
			break;
		bytenr = node->val;
	}

	ulist_free(tmp);
	return 0;
}


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 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124
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!
 */
1125 1126 1127 1128
char *btrfs_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)
1129 1130 1131 1132 1133 1134 1135 1136
{
	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;
1137
	int leave_spinning = path->leave_spinning;
1138 1139 1140 1141

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

1142
	path->leave_spinning = 1;
1143 1144 1145 1146 1147 1148
	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);
1149 1150
		if (eb != eb_in) {
			btrfs_tree_read_unlock_blocking(eb);
1151
			free_extent_buffer(eb);
1152
		}
1153
		ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1154 1155
		if (ret > 0)
			ret = -ENOENT;
1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166
		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 */
1167
		if (eb != eb_in) {
1168
			atomic_inc(&eb->refs);
1169 1170 1171
			btrfs_tree_read_lock(eb);
			btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
		}
1172 1173 1174 1175 1176 1177 1178 1179 1180 1181
		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);
1182
	path->leave_spinning = leave_spinning;
1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219

	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
1220 1221 1222
	    found_key->objectid + found_key->offset <= logical) {
		pr_debug("logical %llu is not within any extent\n",
			 (unsigned long long)logical);
1223
		return -ENOENT;
J
Jan Schmidt 已提交
1224
	}
1225 1226 1227 1228 1229 1230 1231 1232

	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
1233 1234 1235 1236 1237 1238 1239
	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);
1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335
	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;
}

1336 1337
static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
				u64 root, u64 extent_item_objectid,
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1338
				iterate_extent_inodes_t *iterate, void *ctx)
1339
{
1340
	struct extent_inode_elem *eie;
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1341 1342
	int ret = 0;

1343
	for (eie = inode_list; eie; eie = eie->next) {
J
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1344
		pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1345 1346 1347
			 "root %llu\n", extent_item_objectid,
			 eie->inum, eie->offset, root);
		ret = iterate(eie->inum, eie->offset, root, ctx);
J
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1348
		if (ret) {
1349 1350
			pr_debug("stopping iteration for %llu due to ret=%d\n",
				 extent_item_objectid, ret);
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1351 1352
			break;
		}
1353 1354 1355 1356 1357 1358 1359
	}

	return ret;
}

/*
 * calls iterate() for every inode that references the extent identified by
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 * the given parameters.
1361 1362 1363
 * when the iterator function returns a non-zero value, iteration stops.
 */
int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
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				u64 extent_item_objectid, u64 extent_item_pos,
1365
				int search_commit_root,
1366 1367 1368 1369 1370
				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);
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	struct btrfs_trans_handle *trans;
1372 1373
	struct ulist *refs = NULL;
	struct ulist *roots = NULL;
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	struct ulist_node *ref_node = NULL;
	struct ulist_node *root_node = NULL;
1376
	struct seq_list tree_mod_seq_elem = {};
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	struct ulist_iterator ref_uiter;
	struct ulist_iterator root_uiter;
1379

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	pr_debug("resolving all inodes for extent %llu\n",
			extent_item_objectid);
1382

1383 1384 1385 1386 1387 1388
	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);
1389
		btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1390
	}
1391

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	ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1393
				   tree_mod_seq_elem.seq, &refs,
1394
				   &extent_item_pos);
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	if (ret)
		goto out;
1397

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	ULIST_ITER_INIT(&ref_uiter);
	while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1400
		ret = btrfs_find_all_roots(trans, fs_info, ref_node->val,
1401
					   tree_mod_seq_elem.seq, &roots);
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		if (ret)
			break;
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		ULIST_ITER_INIT(&root_uiter);
		while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1406
			pr_debug("root %llu references leaf %llu, data list "
1407
				 "%#llx\n", root_node->val, ref_node->val,
1408 1409 1410 1411 1412 1413
				 (long long)ref_node->aux);
			ret = iterate_leaf_refs((struct extent_inode_elem *)
						(uintptr_t)ref_node->aux,
						root_node->val,
						extent_item_objectid,
						iterate, ctx);
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		}
1415 1416
		ulist_free(roots);
		roots = NULL;
1417 1418
	}

1419
	free_leaf_list(refs);
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	ulist_free(roots);
out:
1422
	if (!search_commit_root) {
1423
		btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1424 1425 1426
		btrfs_end_transaction(trans, fs_info->extent_root);
	}

1427 1428 1429 1430 1431 1432 1433 1434
	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;
1436
	struct btrfs_key found_key;
1437
	int search_commit_root = path->search_commit_root;
1438 1439 1440

	ret = extent_from_logical(fs_info, logical, path,
					&found_key);
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1441
	btrfs_release_path(path);
1442 1443
	if (ret < 0)
		return ret;
1444 1445
	if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
		return -EINVAL;
1446

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	extent_item_pos = logical - found_key.objectid;
1448 1449 1450
	ret = iterate_extent_inodes(fs_info, found_key.objectid,
					extent_item_pos, search_commit_root,
					iterate, ctx);
1451 1452 1453 1454 1455 1456 1457 1458

	return ret;
}

static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
				struct btrfs_path *path,
				iterate_irefs_t *iterate, void *ctx)
{
1459
	int ret = 0;
1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470
	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;

1471
	while (!ret) {
1472
		path->leave_spinning = 1;
1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487
		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);
1488 1489
		btrfs_tree_read_lock(eb);
		btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1490 1491 1492 1493 1494 1495 1496 1497
		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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1498 1499 1500 1501
			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);
1502
			ret = iterate(parent, iref, eb, ctx);
1503
			if (ret)
1504 1505 1506 1507
				break;
			len = sizeof(*iref) + name_len;
			iref = (struct btrfs_inode_ref *)((char *)iref + len);
		}
1508
		btrfs_tree_read_unlock_blocking(eb);
1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533
		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;

1534
	fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1535
	fspath = btrfs_iref_to_path(ipath->fs_root, ipath->btrfs_path, iref, eb,
1536 1537 1538 1539 1540
				inum, fspath_min, bytes_left);
	if (IS_ERR(fspath))
		return PTR_ERR(fspath);

	if (fspath > fspath_min) {
J
Jan Schmidt 已提交
1541
		pr_debug("path resolved: %s\n", fspath);
1542
		ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1543 1544 1545
		++ipath->fspath->elem_cnt;
		ipath->fspath->bytes_left = fspath - fspath_min;
	} else {
J
Jan Schmidt 已提交
1546 1547 1548
		pr_debug("missed path, not enough space. missing bytes: %lu, "
			 "constructed so far: %s\n",
			 (unsigned long)(fspath_min - fspath), fspath_min);
1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559
		++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
1560
 * from ipath->fspath->val[i].
1561
 * when it returns, there are ipath->fspath->elem_cnt number of paths available
1562
 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627
 * 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)
{
1628 1629
	if (!ipath)
		return;
1630
	kfree(ipath->fspath);
1631 1632
	kfree(ipath);
}