// SPDX-License-Identifier: GPL-2.0

  /*
   * Copyright (C) 2011 Fujitsu.  All rights reserved.
   * Written by Miao Xie <miaox@cn.fujitsu.com>

   */
  
  #include <linux/slab.h>

  #include <linux/iversion.h>

  #include "misc.h"

  #include "delayed-inode.h"
  #include "disk-io.h"
  #include "transaction.h"

  #include "ctree.h"

  #include "qgroup.h"

  #define BTRFS_DELAYED_WRITEBACK		512
  #define BTRFS_DELAYED_BACKGROUND	128
  #define BTRFS_DELAYED_BATCH		16

  
  static struct kmem_cache *delayed_node_cache;
  
  int __init btrfs_delayed_inode_init(void)
  {

  	delayed_node_cache = kmem_cache_create("btrfs_delayed_node",

  					sizeof(struct btrfs_delayed_node),
  					0,

  					SLAB_MEM_SPREAD,

  					NULL);
  	if (!delayed_node_cache)
  		return -ENOMEM;
  	return 0;
  }

  void __cold btrfs_delayed_inode_exit(void)

  {

  	kmem_cache_destroy(delayed_node_cache);

  }
  
  static inline void btrfs_init_delayed_node(
  				struct btrfs_delayed_node *delayed_node,
  				struct btrfs_root *root, u64 inode_id)
  {
  	delayed_node->root = root;
  	delayed_node->inode_id = inode_id;

  	refcount_set(&delayed_node->refs, 0);

  	delayed_node->ins_root = RB_ROOT_CACHED;
  	delayed_node->del_root = RB_ROOT_CACHED;

  	mutex_init(&delayed_node->mutex);

  	INIT_LIST_HEAD(&delayed_node->n_list);
  	INIT_LIST_HEAD(&delayed_node->p_list);

  }
  
  static inline int btrfs_is_continuous_delayed_item(
  					struct btrfs_delayed_item *item1,
  					struct btrfs_delayed_item *item2)
  {
  	if (item1->key.type == BTRFS_DIR_INDEX_KEY &&
  	    item1->key.objectid == item2->key.objectid &&
  	    item1->key.type == item2->key.type &&
  	    item1->key.offset + 1 == item2->key.offset)
  		return 1;
  	return 0;
  }

  static struct btrfs_delayed_node *btrfs_get_delayed_node(
  		struct btrfs_inode *btrfs_inode)

  {

  	struct btrfs_root *root = btrfs_inode->root;

  	u64 ino = btrfs_ino(btrfs_inode);

  	struct btrfs_delayed_node *node;

  	node = READ_ONCE(btrfs_inode->delayed_node);

  	if (node) {

  		refcount_inc(&node->refs);

  		return node;
  	}
  
  	spin_lock(&root->inode_lock);

  	node = radix_tree_lookup(&root->delayed_nodes_tree, ino);

  	if (node) {
  		if (btrfs_inode->delayed_node) {

  			refcount_inc(&node->refs);	/* can be accessed */

  			BUG_ON(btrfs_inode->delayed_node != node);

  			spin_unlock(&root->inode_lock);

  			return node;

  		}

  
  		/*
  		 * It's possible that we're racing into the middle of removing
  		 * this node from the radix tree.  In this case, the refcount
  		 * was zero and it should never go back to one.  Just return
  		 * NULL like it was never in the radix at all; our release
  		 * function is in the process of removing it.
  		 *
  		 * Some implementations of refcount_inc refuse to bump the
  		 * refcount once it has hit zero.  If we don't do this dance
  		 * here, refcount_inc() may decide to just WARN_ONCE() instead
  		 * of actually bumping the refcount.
  		 *
  		 * If this node is properly in the radix, we want to bump the
  		 * refcount twice, once for the inode and once for this get
  		 * operation.
  		 */
  		if (refcount_inc_not_zero(&node->refs)) {
  			refcount_inc(&node->refs);
  			btrfs_inode->delayed_node = node;
  		} else {
  			node = NULL;
  		}

  		spin_unlock(&root->inode_lock);
  		return node;
  	}
  	spin_unlock(&root->inode_lock);

  	return NULL;
  }

  /* Will return either the node or PTR_ERR(-ENOMEM) */

  static struct btrfs_delayed_node *btrfs_get_or_create_delayed_node(

  		struct btrfs_inode *btrfs_inode)

  {
  	struct btrfs_delayed_node *node;

  	struct btrfs_root *root = btrfs_inode->root;

  	u64 ino = btrfs_ino(btrfs_inode);

  	int ret;
  
  again:

  	node = btrfs_get_delayed_node(btrfs_inode);

  	if (node)
  		return node;

  	node = kmem_cache_zalloc(delayed_node_cache, GFP_NOFS);

  	if (!node)
  		return ERR_PTR(-ENOMEM);

  	btrfs_init_delayed_node(node, root, ino);

  	/* cached in the btrfs inode and can be accessed */

  	refcount_set(&node->refs, 2);

  	ret = radix_tree_preload(GFP_NOFS);

  	if (ret) {
  		kmem_cache_free(delayed_node_cache, node);
  		return ERR_PTR(ret);
  	}
  
  	spin_lock(&root->inode_lock);

  	ret = radix_tree_insert(&root->delayed_nodes_tree, ino, node);

  	if (ret == -EEXIST) {

  		spin_unlock(&root->inode_lock);

  		kmem_cache_free(delayed_node_cache, node);

  		radix_tree_preload_end();
  		goto again;
  	}
  	btrfs_inode->delayed_node = node;
  	spin_unlock(&root->inode_lock);
  	radix_tree_preload_end();
  
  	return node;
  }
  
  /*
   * Call it when holding delayed_node->mutex
   *
   * If mod = 1, add this node into the prepared list.
   */
  static void btrfs_queue_delayed_node(struct btrfs_delayed_root *root,
  				     struct btrfs_delayed_node *node,
  				     int mod)
  {
  	spin_lock(&root->lock);

  	if (test_bit(BTRFS_DELAYED_NODE_IN_LIST, &node->flags)) {

  		if (!list_empty(&node->p_list))
  			list_move_tail(&node->p_list, &root->prepare_list);
  		else if (mod)
  			list_add_tail(&node->p_list, &root->prepare_list);
  	} else {
  		list_add_tail(&node->n_list, &root->node_list);
  		list_add_tail(&node->p_list, &root->prepare_list);

  		refcount_inc(&node->refs);	/* inserted into list */

  		root->nodes++;

  		set_bit(BTRFS_DELAYED_NODE_IN_LIST, &node->flags);

  	}
  	spin_unlock(&root->lock);
  }
  
  /* Call it when holding delayed_node->mutex */
  static void btrfs_dequeue_delayed_node(struct btrfs_delayed_root *root,
  				       struct btrfs_delayed_node *node)
  {
  	spin_lock(&root->lock);

  	if (test_bit(BTRFS_DELAYED_NODE_IN_LIST, &node->flags)) {

  		root->nodes--;

  		refcount_dec(&node->refs);	/* not in the list */

  		list_del_init(&node->n_list);
  		if (!list_empty(&node->p_list))
  			list_del_init(&node->p_list);

  		clear_bit(BTRFS_DELAYED_NODE_IN_LIST, &node->flags);

  	}
  	spin_unlock(&root->lock);
  }

  static struct btrfs_delayed_node *btrfs_first_delayed_node(

  			struct btrfs_delayed_root *delayed_root)
  {
  	struct list_head *p;
  	struct btrfs_delayed_node *node = NULL;
  
  	spin_lock(&delayed_root->lock);
  	if (list_empty(&delayed_root->node_list))
  		goto out;
  
  	p = delayed_root->node_list.next;
  	node = list_entry(p, struct btrfs_delayed_node, n_list);

  	refcount_inc(&node->refs);

  out:
  	spin_unlock(&delayed_root->lock);
  
  	return node;
  }

  static struct btrfs_delayed_node *btrfs_next_delayed_node(

  						struct btrfs_delayed_node *node)
  {
  	struct btrfs_delayed_root *delayed_root;
  	struct list_head *p;
  	struct btrfs_delayed_node *next = NULL;
  
  	delayed_root = node->root->fs_info->delayed_root;
  	spin_lock(&delayed_root->lock);

  	if (!test_bit(BTRFS_DELAYED_NODE_IN_LIST, &node->flags)) {
  		/* not in the list */

  		if (list_empty(&delayed_root->node_list))
  			goto out;
  		p = delayed_root->node_list.next;
  	} else if (list_is_last(&node->n_list, &delayed_root->node_list))
  		goto out;
  	else
  		p = node->n_list.next;
  
  	next = list_entry(p, struct btrfs_delayed_node, n_list);

  	refcount_inc(&next->refs);

  out:
  	spin_unlock(&delayed_root->lock);
  
  	return next;
  }
  
  static void __btrfs_release_delayed_node(
  				struct btrfs_delayed_node *delayed_node,
  				int mod)
  {
  	struct btrfs_delayed_root *delayed_root;
  
  	if (!delayed_node)
  		return;
  
  	delayed_root = delayed_node->root->fs_info->delayed_root;
  
  	mutex_lock(&delayed_node->mutex);
  	if (delayed_node->count)
  		btrfs_queue_delayed_node(delayed_root, delayed_node, mod);
  	else
  		btrfs_dequeue_delayed_node(delayed_root, delayed_node);
  	mutex_unlock(&delayed_node->mutex);

  	if (refcount_dec_and_test(&delayed_node->refs)) {

  		struct btrfs_root *root = delayed_node->root;

  		spin_lock(&root->inode_lock);

  		/*
  		 * Once our refcount goes to zero, nobody is allowed to bump it
  		 * back up.  We can delete it now.
  		 */
  		ASSERT(refcount_read(&delayed_node->refs) == 0);
  		radix_tree_delete(&root->delayed_nodes_tree,
  				  delayed_node->inode_id);

  		spin_unlock(&root->inode_lock);

  		kmem_cache_free(delayed_node_cache, delayed_node);

  	}
  }
  
  static inline void btrfs_release_delayed_node(struct btrfs_delayed_node *node)
  {
  	__btrfs_release_delayed_node(node, 0);
  }

  static struct btrfs_delayed_node *btrfs_first_prepared_delayed_node(

  					struct btrfs_delayed_root *delayed_root)
  {
  	struct list_head *p;
  	struct btrfs_delayed_node *node = NULL;
  
  	spin_lock(&delayed_root->lock);
  	if (list_empty(&delayed_root->prepare_list))
  		goto out;
  
  	p = delayed_root->prepare_list.next;
  	list_del_init(p);
  	node = list_entry(p, struct btrfs_delayed_node, p_list);

  	refcount_inc(&node->refs);

  out:
  	spin_unlock(&delayed_root->lock);
  
  	return node;
  }
  
  static inline void btrfs_release_prepared_delayed_node(
  					struct btrfs_delayed_node *node)
  {
  	__btrfs_release_delayed_node(node, 1);
  }

  static struct btrfs_delayed_item *btrfs_alloc_delayed_item(u32 data_len)

  {
  	struct btrfs_delayed_item *item;
  	item = kmalloc(sizeof(*item) + data_len, GFP_NOFS);
  	if (item) {
  		item->data_len = data_len;
  		item->ins_or_del = 0;
  		item->bytes_reserved = 0;

  		item->delayed_node = NULL;

  		refcount_set(&item->refs, 1);

  	}
  	return item;
  }
  
  /*
   * __btrfs_lookup_delayed_item - look up the delayed item by key
   * @delayed_node: pointer to the delayed node
   * @key:	  the key to look up
   * @prev:	  used to store the prev item if the right item isn't found
   * @next:	  used to store the next item if the right item isn't found
   *
   * Note: if we don't find the right item, we will return the prev item and
   * the next item.
   */
  static struct btrfs_delayed_item *__btrfs_lookup_delayed_item(
  				struct rb_root *root,
  				struct btrfs_key *key,
  				struct btrfs_delayed_item **prev,
  				struct btrfs_delayed_item **next)
  {
  	struct rb_node *node, *prev_node = NULL;
  	struct btrfs_delayed_item *delayed_item = NULL;
  	int ret = 0;
  
  	node = root->rb_node;
  
  	while (node) {
  		delayed_item = rb_entry(node, struct btrfs_delayed_item,
  					rb_node);
  		prev_node = node;
  		ret = btrfs_comp_cpu_keys(&delayed_item->key, key);
  		if (ret < 0)
  			node = node->rb_right;
  		else if (ret > 0)
  			node = node->rb_left;
  		else
  			return delayed_item;
  	}
  
  	if (prev) {
  		if (!prev_node)
  			*prev = NULL;
  		else if (ret < 0)
  			*prev = delayed_item;
  		else if ((node = rb_prev(prev_node)) != NULL) {
  			*prev = rb_entry(node, struct btrfs_delayed_item,
  					 rb_node);
  		} else
  			*prev = NULL;
  	}
  
  	if (next) {
  		if (!prev_node)
  			*next = NULL;
  		else if (ret > 0)
  			*next = delayed_item;
  		else if ((node = rb_next(prev_node)) != NULL) {
  			*next = rb_entry(node, struct btrfs_delayed_item,
  					 rb_node);
  		} else
  			*next = NULL;
  	}
  	return NULL;
  }

  static struct btrfs_delayed_item *__btrfs_lookup_delayed_insertion_item(

  					struct btrfs_delayed_node *delayed_node,
  					struct btrfs_key *key)
  {

  	return __btrfs_lookup_delayed_item(&delayed_node->ins_root.rb_root, key,

  					   NULL, NULL);

  }

  static int __btrfs_add_delayed_item(struct btrfs_delayed_node *delayed_node,
  				    struct btrfs_delayed_item *ins,
  				    int action)
  {
  	struct rb_node **p, *node;
  	struct rb_node *parent_node = NULL;

  	struct rb_root_cached *root;

  	struct btrfs_delayed_item *item;
  	int cmp;

  	bool leftmost = true;

  
  	if (action == BTRFS_DELAYED_INSERTION_ITEM)
  		root = &delayed_node->ins_root;
  	else if (action == BTRFS_DELAYED_DELETION_ITEM)
  		root = &delayed_node->del_root;
  	else
  		BUG();

  	p = &root->rb_root.rb_node;

  	node = &ins->rb_node;
  
  	while (*p) {
  		parent_node = *p;
  		item = rb_entry(parent_node, struct btrfs_delayed_item,
  				 rb_node);
  
  		cmp = btrfs_comp_cpu_keys(&item->key, &ins->key);

  		if (cmp < 0) {

  			p = &(*p)->rb_right;

  			leftmost = false;
  		} else if (cmp > 0) {

  			p = &(*p)->rb_left;

  		} else {

  			return -EEXIST;

  		}

  	}
  
  	rb_link_node(node, parent_node, p);

  	rb_insert_color_cached(node, root, leftmost);

  	ins->delayed_node = delayed_node;
  	ins->ins_or_del = action;
  
  	if (ins->key.type == BTRFS_DIR_INDEX_KEY &&
  	    action == BTRFS_DELAYED_INSERTION_ITEM &&
  	    ins->key.offset >= delayed_node->index_cnt)
  			delayed_node->index_cnt = ins->key.offset + 1;
  
  	delayed_node->count++;
  	atomic_inc(&delayed_node->root->fs_info->delayed_root->items);
  	return 0;
  }
  
  static int __btrfs_add_delayed_insertion_item(struct btrfs_delayed_node *node,
  					      struct btrfs_delayed_item *item)
  {
  	return __btrfs_add_delayed_item(node, item,
  					BTRFS_DELAYED_INSERTION_ITEM);
  }
  
  static int __btrfs_add_delayed_deletion_item(struct btrfs_delayed_node *node,
  					     struct btrfs_delayed_item *item)
  {
  	return __btrfs_add_delayed_item(node, item,
  					BTRFS_DELAYED_DELETION_ITEM);
  }

  static void finish_one_item(struct btrfs_delayed_root *delayed_root)
  {
  	int seq = atomic_inc_return(&delayed_root->items_seq);

  	/* atomic_dec_return implies a barrier */

  	if ((atomic_dec_return(&delayed_root->items) <

  	    BTRFS_DELAYED_BACKGROUND || seq % BTRFS_DELAYED_BATCH == 0))
  		cond_wake_up_nomb(&delayed_root->wait);

  }

  static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
  {

  	struct rb_root_cached *root;

  	struct btrfs_delayed_root *delayed_root;

  	/* Not associated with any delayed_node */
  	if (!delayed_item->delayed_node)
  		return;

  	delayed_root = delayed_item->delayed_node->root->fs_info->delayed_root;
  
  	BUG_ON(!delayed_root);
  	BUG_ON(delayed_item->ins_or_del != BTRFS_DELAYED_DELETION_ITEM &&
  	       delayed_item->ins_or_del != BTRFS_DELAYED_INSERTION_ITEM);
  
  	if (delayed_item->ins_or_del == BTRFS_DELAYED_INSERTION_ITEM)
  		root = &delayed_item->delayed_node->ins_root;
  	else
  		root = &delayed_item->delayed_node->del_root;

  	rb_erase_cached(&delayed_item->rb_node, root);

  	delayed_item->delayed_node->count--;

  
  	finish_one_item(delayed_root);

  }
  
  static void btrfs_release_delayed_item(struct btrfs_delayed_item *item)
  {
  	if (item) {
  		__btrfs_remove_delayed_item(item);

  		if (refcount_dec_and_test(&item->refs))

  			kfree(item);
  	}
  }

  static struct btrfs_delayed_item *__btrfs_first_delayed_insertion_item(

  					struct btrfs_delayed_node *delayed_node)
  {
  	struct rb_node *p;
  	struct btrfs_delayed_item *item = NULL;

  	p = rb_first_cached(&delayed_node->ins_root);

  	if (p)
  		item = rb_entry(p, struct btrfs_delayed_item, rb_node);
  
  	return item;
  }

  static struct btrfs_delayed_item *__btrfs_first_delayed_deletion_item(

  					struct btrfs_delayed_node *delayed_node)
  {
  	struct rb_node *p;
  	struct btrfs_delayed_item *item = NULL;

  	p = rb_first_cached(&delayed_node->del_root);

  	if (p)
  		item = rb_entry(p, struct btrfs_delayed_item, rb_node);
  
  	return item;
  }

  static struct btrfs_delayed_item *__btrfs_next_delayed_item(

  						struct btrfs_delayed_item *item)
  {
  	struct rb_node *p;
  	struct btrfs_delayed_item *next = NULL;
  
  	p = rb_next(&item->rb_node);
  	if (p)
  		next = rb_entry(p, struct btrfs_delayed_item, rb_node);
  
  	return next;
  }

  static int btrfs_delayed_item_reserve_metadata(struct btrfs_trans_handle *trans,

  					       struct btrfs_root *root,

  					       struct btrfs_delayed_item *item)
  {
  	struct btrfs_block_rsv *src_rsv;
  	struct btrfs_block_rsv *dst_rsv;

  	struct btrfs_fs_info *fs_info = root->fs_info;

  	u64 num_bytes;
  	int ret;
  
  	if (!trans->bytes_reserved)
  		return 0;
  
  	src_rsv = trans->block_rsv;

  	dst_rsv = &fs_info->delayed_block_rsv;

  	num_bytes = btrfs_calc_insert_metadata_size(fs_info, 1);

  
  	/*
  	 * Here we migrate space rsv from transaction rsv, since have already
  	 * reserved space when starting a transaction.  So no need to reserve
  	 * qgroup space here.
  	 */

  	ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes, true);

  	if (!ret) {

  		trace_btrfs_space_reservation(fs_info, "delayed_item",

  					      item->key.objectid,
  					      num_bytes, 1);

  		item->bytes_reserved = num_bytes;

  	}

  
  	return ret;
  }

  static void btrfs_delayed_item_release_metadata(struct btrfs_root *root,

  						struct btrfs_delayed_item *item)
  {

  	struct btrfs_block_rsv *rsv;

  	struct btrfs_fs_info *fs_info = root->fs_info;

  	if (!item->bytes_reserved)
  		return;

  	rsv = &fs_info->delayed_block_rsv;

  	/*
  	 * Check btrfs_delayed_item_reserve_metadata() to see why we don't need
  	 * to release/reserve qgroup space.
  	 */

  	trace_btrfs_space_reservation(fs_info, "delayed_item",

  				      item->key.objectid, item->bytes_reserved,
  				      0);

  	btrfs_block_rsv_release(fs_info, rsv,

  				item->bytes_reserved);
  }
  
  static int btrfs_delayed_inode_reserve_metadata(
  					struct btrfs_trans_handle *trans,
  					struct btrfs_root *root,

  					struct btrfs_inode *inode,

  					struct btrfs_delayed_node *node)
  {

  	struct btrfs_fs_info *fs_info = root->fs_info;

  	struct btrfs_block_rsv *src_rsv;
  	struct btrfs_block_rsv *dst_rsv;
  	u64 num_bytes;
  	int ret;

  	src_rsv = trans->block_rsv;

  	dst_rsv = &fs_info->delayed_block_rsv;

  	num_bytes = btrfs_calc_metadata_size(fs_info, 1);

  
  	/*
  	 * btrfs_dirty_inode will update the inode under btrfs_join_transaction
  	 * which doesn't reserve space for speed.  This is a problem since we
  	 * still need to reserve space for this update, so try to reserve the
  	 * space.
  	 *
  	 * Now if src_rsv == delalloc_block_rsv we'll let it just steal since

  	 * we always reserve enough to update the inode item.

  	 */

  	if (!src_rsv || (!trans->bytes_reserved &&

  			 src_rsv->type != BTRFS_BLOCK_RSV_DELALLOC)) {

  		ret = btrfs_qgroup_reserve_meta_prealloc(root,
  				fs_info->nodesize, true);
  		if (ret < 0)
  			return ret;

  		ret = btrfs_block_rsv_add(root, dst_rsv, num_bytes,
  					  BTRFS_RESERVE_NO_FLUSH);

  		/*
  		 * Since we're under a transaction reserve_metadata_bytes could
  		 * try to commit the transaction which will make it return
  		 * EAGAIN to make us stop the transaction we have, so return
  		 * ENOSPC instead so that btrfs_dirty_inode knows what to do.
  		 */

  		if (ret == -EAGAIN) {

  			ret = -ENOSPC;

  			btrfs_qgroup_free_meta_prealloc(root, num_bytes);
  		}

  		if (!ret) {

  			node->bytes_reserved = num_bytes;

  			trace_btrfs_space_reservation(fs_info,

  						      "delayed_inode",

  						      btrfs_ino(inode),

  						      num_bytes, 1);

  		} else {
  			btrfs_qgroup_free_meta_prealloc(root, fs_info->nodesize);

  		}

  		return ret;
  	}

  	ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes, true);

  	if (!ret) {

  		trace_btrfs_space_reservation(fs_info, "delayed_inode",

  					      btrfs_ino(inode), num_bytes, 1);

  		node->bytes_reserved = num_bytes;

  	}

  
  	return ret;
  }

  static void btrfs_delayed_inode_release_metadata(struct btrfs_fs_info *fs_info,

  						struct btrfs_delayed_node *node,
  						bool qgroup_free)

  {
  	struct btrfs_block_rsv *rsv;
  
  	if (!node->bytes_reserved)
  		return;

  	rsv = &fs_info->delayed_block_rsv;
  	trace_btrfs_space_reservation(fs_info, "delayed_inode",

  				      node->inode_id, node->bytes_reserved, 0);

  	btrfs_block_rsv_release(fs_info, rsv,

  				node->bytes_reserved);

  	if (qgroup_free)
  		btrfs_qgroup_free_meta_prealloc(node->root,
  				node->bytes_reserved);
  	else
  		btrfs_qgroup_convert_reserved_meta(node->root,
  				node->bytes_reserved);

  	node->bytes_reserved = 0;
  }
  
  /*
   * This helper will insert some continuous items into the same leaf according
   * to the free space of the leaf.
   */

  static int btrfs_batch_insert_items(struct btrfs_root *root,
  				    struct btrfs_path *path,
  				    struct btrfs_delayed_item *item)

  {
  	struct btrfs_delayed_item *curr, *next;
  	int free_space;
  	int total_data_size = 0, total_size = 0;
  	struct extent_buffer *leaf;
  	char *data_ptr;
  	struct btrfs_key *keys;
  	u32 *data_size;
  	struct list_head head;
  	int slot;
  	int nitems;
  	int i;
  	int ret = 0;
  
  	BUG_ON(!path->nodes[0]);
  
  	leaf = path->nodes[0];

  	free_space = btrfs_leaf_free_space(leaf);

  	INIT_LIST_HEAD(&head);
  
  	next = item;

  	nitems = 0;

  
  	/*
  	 * count the number of the continuous items that we can insert in batch
  	 */
  	while (total_size + next->data_len + sizeof(struct btrfs_item) <=
  	       free_space) {
  		total_data_size += next->data_len;
  		total_size += next->data_len + sizeof(struct btrfs_item);
  		list_add_tail(&next->tree_list, &head);
  		nitems++;
  
  		curr = next;
  		next = __btrfs_next_delayed_item(curr);
  		if (!next)
  			break;
  
  		if (!btrfs_is_continuous_delayed_item(curr, next))
  			break;
  	}
  
  	if (!nitems) {
  		ret = 0;
  		goto out;
  	}
  
  	/*
  	 * we need allocate some memory space, but it might cause the task
  	 * to sleep, so we set all locked nodes in the path to blocking locks
  	 * first.
  	 */
  	btrfs_set_path_blocking(path);

  	keys = kmalloc_array(nitems, sizeof(struct btrfs_key), GFP_NOFS);

  	if (!keys) {
  		ret = -ENOMEM;
  		goto out;
  	}

  	data_size = kmalloc_array(nitems, sizeof(u32), GFP_NOFS);

  	if (!data_size) {
  		ret = -ENOMEM;
  		goto error;
  	}
  
  	/* get keys of all the delayed items */
  	i = 0;
  	list_for_each_entry(next, &head, tree_list) {
  		keys[i] = next->key;
  		data_size[i] = next->data_len;
  		i++;
  	}

  	/* insert the keys of the items */

  	setup_items_for_insert(root, path, keys, data_size,

  			       total_data_size, total_size, nitems);

  
  	/* insert the dir index items */
  	slot = path->slots[0];
  	list_for_each_entry_safe(curr, next, &head, tree_list) {
  		data_ptr = btrfs_item_ptr(leaf, slot, char);
  		write_extent_buffer(leaf, &curr->data,
  				    (unsigned long)data_ptr,
  				    curr->data_len);
  		slot++;

  		btrfs_delayed_item_release_metadata(root, curr);

  
  		list_del(&curr->tree_list);
  		btrfs_release_delayed_item(curr);
  	}
  
  error:
  	kfree(data_size);
  	kfree(keys);
  out:
  	return ret;
  }
  
  /*
   * This helper can just do simple insertion that needn't extend item for new
   * data, such as directory name index insertion, inode insertion.
   */
  static int btrfs_insert_delayed_item(struct btrfs_trans_handle *trans,
  				     struct btrfs_root *root,
  				     struct btrfs_path *path,
  				     struct btrfs_delayed_item *delayed_item)
  {
  	struct extent_buffer *leaf;

  	char *ptr;
  	int ret;
  
  	ret = btrfs_insert_empty_item(trans, root, path, &delayed_item->key,
  				      delayed_item->data_len);
  	if (ret < 0 && ret != -EEXIST)
  		return ret;
  
  	leaf = path->nodes[0];

  	ptr = btrfs_item_ptr(leaf, path->slots[0], char);
  
  	write_extent_buffer(leaf, delayed_item->data, (unsigned long)ptr,
  			    delayed_item->data_len);
  	btrfs_mark_buffer_dirty(leaf);

  	btrfs_delayed_item_release_metadata(root, delayed_item);

  	return 0;
  }
  
  /*
   * we insert an item first, then if there are some continuous items, we try
   * to insert those items into the same leaf.
   */
  static int btrfs_insert_delayed_items(struct btrfs_trans_handle *trans,
  				      struct btrfs_path *path,
  				      struct btrfs_root *root,
  				      struct btrfs_delayed_node *node)
  {
  	struct btrfs_delayed_item *curr, *prev;
  	int ret = 0;
  
  do_again:
  	mutex_lock(&node->mutex);
  	curr = __btrfs_first_delayed_insertion_item(node);
  	if (!curr)
  		goto insert_end;
  
  	ret = btrfs_insert_delayed_item(trans, root, path, curr);
  	if (ret < 0) {

  		btrfs_release_path(path);

  		goto insert_end;
  	}
  
  	prev = curr;
  	curr = __btrfs_next_delayed_item(prev);
  	if (curr && btrfs_is_continuous_delayed_item(prev, curr)) {
  		/* insert the continuous items into the same leaf */
  		path->slots[0]++;

  		btrfs_batch_insert_items(root, path, curr);

  	}
  	btrfs_release_delayed_item(prev);
  	btrfs_mark_buffer_dirty(path->nodes[0]);

  	btrfs_release_path(path);

  	mutex_unlock(&node->mutex);
  	goto do_again;
  
  insert_end:
  	mutex_unlock(&node->mutex);
  	return ret;
  }
  
  static int btrfs_batch_delete_items(struct btrfs_trans_handle *trans,
  				    struct btrfs_root *root,
  				    struct btrfs_path *path,
  				    struct btrfs_delayed_item *item)
  {
  	struct btrfs_delayed_item *curr, *next;
  	struct extent_buffer *leaf;
  	struct btrfs_key key;
  	struct list_head head;
  	int nitems, i, last_item;
  	int ret = 0;
  
  	BUG_ON(!path->nodes[0]);
  
  	leaf = path->nodes[0];
  
  	i = path->slots[0];
  	last_item = btrfs_header_nritems(leaf) - 1;
  	if (i > last_item)
  		return -ENOENT;	/* FIXME: Is errno suitable? */
  
  	next = item;
  	INIT_LIST_HEAD(&head);
  	btrfs_item_key_to_cpu(leaf, &key, i);
  	nitems = 0;
  	/*
  	 * count the number of the dir index items that we can delete in batch
  	 */
  	while (btrfs_comp_cpu_keys(&next->key, &key) == 0) {
  		list_add_tail(&next->tree_list, &head);
  		nitems++;
  
  		curr = next;
  		next = __btrfs_next_delayed_item(curr);
  		if (!next)
  			break;
  
  		if (!btrfs_is_continuous_delayed_item(curr, next))
  			break;
  
  		i++;
  		if (i > last_item)
  			break;
  		btrfs_item_key_to_cpu(leaf, &key, i);
  	}
  
  	if (!nitems)
  		return 0;
  
  	ret = btrfs_del_items(trans, root, path, path->slots[0], nitems);
  	if (ret)
  		goto out;
  
  	list_for_each_entry_safe(curr, next, &head, tree_list) {

  		btrfs_delayed_item_release_metadata(root, curr);

  		list_del(&curr->tree_list);
  		btrfs_release_delayed_item(curr);
  	}
  
  out:
  	return ret;
  }
  
  static int btrfs_delete_delayed_items(struct btrfs_trans_handle *trans,
  				      struct btrfs_path *path,
  				      struct btrfs_root *root,
  				      struct btrfs_delayed_node *node)
  {
  	struct btrfs_delayed_item *curr, *prev;
  	int ret = 0;
  
  do_again:
  	mutex_lock(&node->mutex);
  	curr = __btrfs_first_delayed_deletion_item(node);
  	if (!curr)
  		goto delete_fail;
  
  	ret = btrfs_search_slot(trans, root, &curr->key, path, -1, 1);
  	if (ret < 0)
  		goto delete_fail;
  	else if (ret > 0) {
  		/*
  		 * can't find the item which the node points to, so this node
  		 * is invalid, just drop it.
  		 */
  		prev = curr;
  		curr = __btrfs_next_delayed_item(prev);
  		btrfs_release_delayed_item(prev);
  		ret = 0;

  		btrfs_release_path(path);

  		if (curr) {
  			mutex_unlock(&node->mutex);

  			goto do_again;

  		} else

  			goto delete_fail;
  	}
  
  	btrfs_batch_delete_items(trans, root, path, curr);

  	btrfs_release_path(path);

  	mutex_unlock(&node->mutex);
  	goto do_again;
  
  delete_fail:

  	btrfs_release_path(path);

  	mutex_unlock(&node->mutex);
  	return ret;
  }
  
  static void btrfs_release_delayed_inode(struct btrfs_delayed_node *delayed_node)
  {
  	struct btrfs_delayed_root *delayed_root;

  	if (delayed_node &&
  	    test_bit(BTRFS_DELAYED_NODE_INODE_DIRTY, &delayed_node->flags)) {

  		BUG_ON(!delayed_node->root);

  		clear_bit(BTRFS_DELAYED_NODE_INODE_DIRTY, &delayed_node->flags);

  		delayed_node->count--;
  
  		delayed_root = delayed_node->root->fs_info->delayed_root;

  		finish_one_item(delayed_root);

  	}
  }

  static void btrfs_release_delayed_iref(struct btrfs_delayed_node *delayed_node)
  {
  	struct btrfs_delayed_root *delayed_root;
  
  	ASSERT(delayed_node->root);
  	clear_bit(BTRFS_DELAYED_NODE_DEL_IREF, &delayed_node->flags);
  	delayed_node->count--;
  
  	delayed_root = delayed_node->root->fs_info->delayed_root;
  	finish_one_item(delayed_root);
  }

  static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
  					struct btrfs_root *root,
  					struct btrfs_path *path,
  					struct btrfs_delayed_node *node)

  {

  	struct btrfs_fs_info *fs_info = root->fs_info;

  	struct btrfs_key key;
  	struct btrfs_inode_item *inode_item;
  	struct extent_buffer *leaf;

  	int mod;

  	int ret;

  	key.objectid = node->inode_id;

  	key.type = BTRFS_INODE_ITEM_KEY;

  	key.offset = 0;

  	if (test_bit(BTRFS_DELAYED_NODE_DEL_IREF, &node->flags))
  		mod = -1;
  	else
  		mod = 1;
  
  	ret = btrfs_lookup_inode(trans, root, path, &key, mod);

  	if (ret > 0) {

  		btrfs_release_path(path);

  		return -ENOENT;
  	} else if (ret < 0) {

  		return ret;
  	}

  	leaf = path->nodes[0];
  	inode_item = btrfs_item_ptr(leaf, path->slots[0],
  				    struct btrfs_inode_item);
  	write_extent_buffer(leaf, &node->inode_item, (unsigned long)inode_item,
  			    sizeof(struct btrfs_inode_item));
  	btrfs_mark_buffer_dirty(leaf);

  	if (!test_bit(BTRFS_DELAYED_NODE_DEL_IREF, &node->flags))
  		goto no_iref;
  
  	path->slots[0]++;
  	if (path->slots[0] >= btrfs_header_nritems(leaf))
  		goto search;
  again:
  	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
  	if (key.objectid != node->inode_id)
  		goto out;
  
  	if (key.type != BTRFS_INODE_REF_KEY &&
  	    key.type != BTRFS_INODE_EXTREF_KEY)
  		goto out;
  
  	/*
  	 * Delayed iref deletion is for the inode who has only one link,
  	 * so there is only one iref. The case that several irefs are
  	 * in the same item doesn't exist.
  	 */
  	btrfs_del_item(trans, root, path);
  out:
  	btrfs_release_delayed_iref(node);
  no_iref:
  	btrfs_release_path(path);
  err_out:

  	btrfs_delayed_inode_release_metadata(fs_info, node, (ret < 0));

  	btrfs_release_delayed_inode(node);

  	return ret;
  
  search:
  	btrfs_release_path(path);

  	key.type = BTRFS_INODE_EXTREF_KEY;

  	key.offset = -1;
  	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
  	if (ret < 0)
  		goto err_out;
  	ASSERT(ret);
  
  	ret = 0;
  	leaf = path->nodes[0];
  	path->slots[0]--;
  	goto again;

  }

  static inline int btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
  					     struct btrfs_root *root,
  					     struct btrfs_path *path,
  					     struct btrfs_delayed_node *node)
  {
  	int ret;
  
  	mutex_lock(&node->mutex);

  	if (!test_bit(BTRFS_DELAYED_NODE_INODE_DIRTY, &node->flags)) {

  		mutex_unlock(&node->mutex);
  		return 0;
  	}
  
  	ret = __btrfs_update_delayed_inode(trans, root, path, node);
  	mutex_unlock(&node->mutex);
  	return ret;
  }

  static inline int
  __btrfs_commit_inode_delayed_items(struct btrfs_trans_handle *trans,
  				   struct btrfs_path *path,
  				   struct btrfs_delayed_node *node)
  {
  	int ret;
  
  	ret = btrfs_insert_delayed_items(trans, path, node->root, node);
  	if (ret)
  		return ret;
  
  	ret = btrfs_delete_delayed_items(trans, path, node->root, node);
  	if (ret)
  		return ret;
  
  	ret = btrfs_update_delayed_inode(trans, node->root, path, node);
  	return ret;
  }

  /*
   * Called when committing the transaction.
   * Returns 0 on success.
   * Returns < 0 on error and returns with an aborted transaction with any
   * outstanding delayed items cleaned up.
   */

  static int __btrfs_run_delayed_items(struct btrfs_trans_handle *trans, int nr)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct btrfs_delayed_root *delayed_root;
  	struct btrfs_delayed_node *curr_node, *prev_node;
  	struct btrfs_path *path;

  	struct btrfs_block_rsv *block_rsv;

  	int ret = 0;

  	bool count = (nr > 0);

  	if (trans->aborted)
  		return -EIO;

  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  	path->leave_spinning = 1;

  	block_rsv = trans->block_rsv;

  	trans->block_rsv = &fs_info->delayed_block_rsv;

  	delayed_root = fs_info->delayed_root;

  
  	curr_node = btrfs_first_delayed_node(delayed_root);

  	while (curr_node && (!count || (count && nr--))) {

  		ret = __btrfs_commit_inode_delayed_items(trans, path,
  							 curr_node);

  		if (ret) {
  			btrfs_release_delayed_node(curr_node);

  			curr_node = NULL;

  			btrfs_abort_transaction(trans, ret);

  			break;
  		}
  
  		prev_node = curr_node;
  		curr_node = btrfs_next_delayed_node(curr_node);
  		btrfs_release_delayed_node(prev_node);
  	}

  	if (curr_node)
  		btrfs_release_delayed_node(curr_node);

  	btrfs_free_path(path);

  	trans->block_rsv = block_rsv;

  	return ret;
  }

  int btrfs_run_delayed_items(struct btrfs_trans_handle *trans)

  {

  	return __btrfs_run_delayed_items(trans, -1);

  }

  int btrfs_run_delayed_items_nr(struct btrfs_trans_handle *trans, int nr)

  {

  	return __btrfs_run_delayed_items(trans, nr);

  }

  int btrfs_commit_inode_delayed_items(struct btrfs_trans_handle *trans,

  				     struct btrfs_inode *inode)

  {

  	struct btrfs_delayed_node *delayed_node = btrfs_get_delayed_node(inode);

  	struct btrfs_path *path;
  	struct btrfs_block_rsv *block_rsv;

  	int ret;
  
  	if (!delayed_node)
  		return 0;
  
  	mutex_lock(&delayed_node->mutex);
  	if (!delayed_node->count) {
  		mutex_unlock(&delayed_node->mutex);
  		btrfs_release_delayed_node(delayed_node);
  		return 0;
  	}
  	mutex_unlock(&delayed_node->mutex);

  	path = btrfs_alloc_path();

  	if (!path) {
  		btrfs_release_delayed_node(delayed_node);

  		return -ENOMEM;

  	}

  	path->leave_spinning = 1;
  
  	block_rsv = trans->block_rsv;
  	trans->block_rsv = &delayed_node->root->fs_info->delayed_block_rsv;
  
  	ret = __btrfs_commit_inode_delayed_items(trans, path, delayed_node);

  	btrfs_release_delayed_node(delayed_node);

  	btrfs_free_path(path);
  	trans->block_rsv = block_rsv;

  	return ret;
  }

  int btrfs_commit_inode_delayed_inode(struct btrfs_inode *inode)

  {

  	struct btrfs_fs_info *fs_info = inode->root->fs_info;

  	struct btrfs_trans_handle *trans;

  	struct btrfs_delayed_node *delayed_node = btrfs_get_delayed_node(inode);

  	struct btrfs_path *path;
  	struct btrfs_block_rsv *block_rsv;
  	int ret;
  
  	if (!delayed_node)
  		return 0;
  
  	mutex_lock(&delayed_node->mutex);

  	if (!test_bit(BTRFS_DELAYED_NODE_INODE_DIRTY, &delayed_node->flags)) {

  		mutex_unlock(&delayed_node->mutex);
  		btrfs_release_delayed_node(delayed_node);
  		return 0;
  	}
  	mutex_unlock(&delayed_node->mutex);
  
  	trans = btrfs_join_transaction(delayed_node->root);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out;
  	}
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto trans_out;
  	}
  	path->leave_spinning = 1;
  
  	block_rsv = trans->block_rsv;

  	trans->block_rsv = &fs_info->delayed_block_rsv;

  
  	mutex_lock(&delayed_node->mutex);

  	if (test_bit(BTRFS_DELAYED_NODE_INODE_DIRTY, &delayed_node->flags))

  		ret = __btrfs_update_delayed_inode(trans, delayed_node->root,
  						   path, delayed_node);
  	else
  		ret = 0;
  	mutex_unlock(&delayed_node->mutex);
  
  	btrfs_free_path(path);
  	trans->block_rsv = block_rsv;
  trans_out:

  	btrfs_end_transaction(trans);

  	btrfs_btree_balance_dirty(fs_info);

  out:
  	btrfs_release_delayed_node(delayed_node);
  
  	return ret;
  }

  void btrfs_remove_delayed_node(struct btrfs_inode *inode)

  {
  	struct btrfs_delayed_node *delayed_node;

  	delayed_node = READ_ONCE(inode->delayed_node);

  	if (!delayed_node)
  		return;

  	inode->delayed_node = NULL;

  	btrfs_release_delayed_node(delayed_node);
  }

  struct btrfs_async_delayed_work {
  	struct btrfs_delayed_root *delayed_root;
  	int nr;

  	struct btrfs_work work;

  };

  static void btrfs_async_run_delayed_root(struct btrfs_work *work)

  {

  	struct btrfs_async_delayed_work *async_work;
  	struct btrfs_delayed_root *delayed_root;

  	struct btrfs_trans_handle *trans;
  	struct btrfs_path *path;
  	struct btrfs_delayed_node *delayed_node = NULL;
  	struct btrfs_root *root;

  	struct btrfs_block_rsv *block_rsv;

  	int total_done = 0;

  	async_work = container_of(work, struct btrfs_async_delayed_work, work);
  	delayed_root = async_work->delayed_root;

  
  	path = btrfs_alloc_path();
  	if (!path)
  		goto out;

  	do {
  		if (atomic_read(&delayed_root->items) <
  		    BTRFS_DELAYED_BACKGROUND / 2)
  			break;

  		delayed_node = btrfs_first_prepared_delayed_node(delayed_root);
  		if (!delayed_node)
  			break;

  		path->leave_spinning = 1;
  		root = delayed_node->root;

  		trans = btrfs_join_transaction(root);
  		if (IS_ERR(trans)) {
  			btrfs_release_path(path);
  			btrfs_release_prepared_delayed_node(delayed_node);
  			total_done++;
  			continue;
  		}

  		block_rsv = trans->block_rsv;
  		trans->block_rsv = &root->fs_info->delayed_block_rsv;

  		__btrfs_commit_inode_delayed_items(trans, path, delayed_node);

  		trans->block_rsv = block_rsv;
  		btrfs_end_transaction(trans);
  		btrfs_btree_balance_dirty_nodelay(root->fs_info);

  		btrfs_release_path(path);
  		btrfs_release_prepared_delayed_node(delayed_node);
  		total_done++;

  	} while ((async_work->nr == 0 && total_done < BTRFS_DELAYED_WRITEBACK)
  		 || total_done < async_work->nr);

  	btrfs_free_path(path);
  out:

  	wake_up(&delayed_root->wait);
  	kfree(async_work);

  }

  static int btrfs_wq_run_delayed_node(struct btrfs_delayed_root *delayed_root,

  				     struct btrfs_fs_info *fs_info, int nr)

  {

  	struct btrfs_async_delayed_work *async_work;

  	async_work = kmalloc(sizeof(*async_work), GFP_NOFS);
  	if (!async_work)

  		return -ENOMEM;

  	async_work->delayed_root = delayed_root;

  	btrfs_init_work(&async_work->work, btrfs_async_run_delayed_root, NULL,
  			NULL);

  	async_work->nr = nr;

  	btrfs_queue_work(fs_info->delayed_workers, &async_work->work);

  	return 0;
  }

  void btrfs_assert_delayed_root_empty(struct btrfs_fs_info *fs_info)

  {

  	WARN_ON(btrfs_first_delayed_node(fs_info->delayed_root));

  }

  static int could_end_wait(struct btrfs_delayed_root *delayed_root, int seq)

  {
  	int val = atomic_read(&delayed_root->items_seq);

  	if (val < seq || val >= seq + BTRFS_DELAYED_BATCH)

  		return 1;

  
  	if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND)
  		return 1;

  	return 0;
  }

  void btrfs_balance_delayed_items(struct btrfs_fs_info *fs_info)

  {

  	struct btrfs_delayed_root *delayed_root = fs_info->delayed_root;

  	if ((atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND) ||
  		btrfs_workqueue_normal_congested(fs_info->delayed_workers))

  		return;
  
  	if (atomic_read(&delayed_root->items) >= BTRFS_DELAYED_WRITEBACK) {

  		int seq;

  		int ret;

  
  		seq = atomic_read(&delayed_root->items_seq);

  		ret = btrfs_wq_run_delayed_node(delayed_root, fs_info, 0);

  		if (ret)
  			return;

  		wait_event_interruptible(delayed_root->wait,
  					 could_end_wait(delayed_root, seq));

  		return;

  	}

  	btrfs_wq_run_delayed_node(delayed_root, fs_info, BTRFS_DELAYED_BATCH);

  }

  /* Will return 0 or -ENOMEM */

  int btrfs_insert_delayed_dir_index(struct btrfs_trans_handle *trans,

  				   const char *name, int name_len,

  				   struct btrfs_inode *dir,

  				   struct btrfs_disk_key *disk_key, u8 type,
  				   u64 index)
  {
  	struct btrfs_delayed_node *delayed_node;
  	struct btrfs_delayed_item *delayed_item;
  	struct btrfs_dir_item *dir_item;
  	int ret;

  	delayed_node = btrfs_get_or_create_delayed_node(dir);

  	if (IS_ERR(delayed_node))
  		return PTR_ERR(delayed_node);
  
  	delayed_item = btrfs_alloc_delayed_item(sizeof(*dir_item) + name_len);
  	if (!delayed_item) {
  		ret = -ENOMEM;
  		goto release_node;
  	}

  	delayed_item->key.objectid = btrfs_ino(dir);

  	delayed_item->key.type = BTRFS_DIR_INDEX_KEY;

  	delayed_item->key.offset = index;
  
  	dir_item = (struct btrfs_dir_item *)delayed_item->data;
  	dir_item->location = *disk_key;

  	btrfs_set_stack_dir_transid(dir_item, trans->transid);
  	btrfs_set_stack_dir_data_len(dir_item, 0);
  	btrfs_set_stack_dir_name_len(dir_item, name_len);
  	btrfs_set_stack_dir_type(dir_item, type);

  	memcpy((char *)(dir_item + 1), name, name_len);

  	ret = btrfs_delayed_item_reserve_metadata(trans, dir->root, delayed_item);

  	/*
  	 * we have reserved enough space when we start a new transaction,
  	 * so reserving metadata failure is impossible
  	 */
  	BUG_ON(ret);

  	mutex_lock(&delayed_node->mutex);
  	ret = __btrfs_add_delayed_insertion_item(delayed_node, delayed_item);
  	if (unlikely(ret)) {

  		btrfs_err(trans->fs_info,

  			  "err add delayed dir index item(name: %.*s) into the insertion tree of the delayed node(root id: %llu, inode id: %llu, errno: %d)",

  			  name_len, name, delayed_node->root->root_key.objectid,

  			  delayed_node->inode_id, ret);

  		BUG();
  	}
  	mutex_unlock(&delayed_node->mutex);
  
  release_node:
  	btrfs_release_delayed_node(delayed_node);
  	return ret;
  }

  static int btrfs_delete_delayed_insertion_item(struct btrfs_fs_info *fs_info,

  					       struct btrfs_delayed_node *node,
  					       struct btrfs_key *key)
  {
  	struct btrfs_delayed_item *item;
  
  	mutex_lock(&node->mutex);
  	item = __btrfs_lookup_delayed_insertion_item(node, key);
  	if (!item) {
  		mutex_unlock(&node->mutex);
  		return 1;
  	}

  	btrfs_delayed_item_release_metadata(node->root, item);

  	btrfs_release_delayed_item(item);
  	mutex_unlock(&node->mutex);
  	return 0;
  }
  
  int btrfs_delete_delayed_dir_index(struct btrfs_trans_handle *trans,

  				   struct btrfs_inode *dir, u64 index)

  {
  	struct btrfs_delayed_node *node;
  	struct btrfs_delayed_item *item;
  	struct btrfs_key item_key;
  	int ret;

  	node = btrfs_get_or_create_delayed_node(dir);

  	if (IS_ERR(node))
  		return PTR_ERR(node);

  	item_key.objectid = btrfs_ino(dir);

  	item_key.type = BTRFS_DIR_INDEX_KEY;

  	item_key.offset = index;

  	ret = btrfs_delete_delayed_insertion_item(trans->fs_info, node,
  						  &item_key);

  	if (!ret)
  		goto end;
  
  	item = btrfs_alloc_delayed_item(0);
  	if (!item) {
  		ret = -ENOMEM;
  		goto end;
  	}
  
  	item->key = item_key;

  	ret = btrfs_delayed_item_reserve_metadata(trans, dir->root, item);

  	/*
  	 * we have reserved enough space when we start a new transaction,
  	 * so reserving metadata failure is impossible.
  	 */

  	if (ret < 0) {
  		btrfs_err(trans->fs_info,
  "metadata reservation failed for delayed dir item deltiona, should have been reserved");
  		btrfs_release_delayed_item(item);
  		goto end;
  	}

  
  	mutex_lock(&node->mutex);
  	ret = __btrfs_add_delayed_deletion_item(node, item);
  	if (unlikely(ret)) {

  		btrfs_err(trans->fs_info,

  			  "err add delayed dir index item(index: %llu) into the deletion tree of the delayed node(root id: %llu, inode id: %llu, errno: %d)",

  			  index, node->root->root_key.objectid,
  			  node->inode_id, ret);

  		btrfs_delayed_item_release_metadata(dir->root, item);
  		btrfs_release_delayed_item(item);

  	}
  	mutex_unlock(&node->mutex);
  end:
  	btrfs_release_delayed_node(node);
  	return ret;
  }

  int btrfs_inode_delayed_dir_index_count(struct btrfs_inode *inode)

  {

  	struct btrfs_delayed_node *delayed_node = btrfs_get_delayed_node(inode);

  
  	if (!delayed_node)
  		return -ENOENT;
  
  	/*
  	 * Since we have held i_mutex of this directory, it is impossible that
  	 * a new directory index is added into the delayed node and index_cnt
  	 * is updated now. So we needn't lock the delayed node.
  	 */

  	if (!delayed_node->index_cnt) {
  		btrfs_release_delayed_node(delayed_node);

  		return -EINVAL;

  	}

  	inode->index_cnt = delayed_node->index_cnt;

  	btrfs_release_delayed_node(delayed_node);
  	return 0;

  }

  bool btrfs_readdir_get_delayed_items(struct inode *inode,
  				     struct list_head *ins_list,
  				     struct list_head *del_list)

  {
  	struct btrfs_delayed_node *delayed_node;
  	struct btrfs_delayed_item *item;

  	delayed_node = btrfs_get_delayed_node(BTRFS_I(inode));

  	if (!delayed_node)

  		return false;
  
  	/*
  	 * We can only do one readdir with delayed items at a time because of
  	 * item->readdir_list.
  	 */
  	inode_unlock_shared(inode);
  	inode_lock(inode);

  
  	mutex_lock(&delayed_node->mutex);
  	item = __btrfs_first_delayed_insertion_item(delayed_node);
  	while (item) {

  		refcount_inc(&item->refs);

  		list_add_tail(&item->readdir_list, ins_list);
  		item = __btrfs_next_delayed_item(item);
  	}
  
  	item = __btrfs_first_delayed_deletion_item(delayed_node);
  	while (item) {

  		refcount_inc(&item->refs);

  		list_add_tail(&item->readdir_list, del_list);
  		item = __btrfs_next_delayed_item(item);
  	}
  	mutex_unlock(&delayed_node->mutex);
  	/*
  	 * This delayed node is still cached in the btrfs inode, so refs
  	 * must be > 1 now, and we needn't check it is going to be freed
  	 * or not.
  	 *
  	 * Besides that, this function is used to read dir, we do not
  	 * insert/delete delayed items in this period. So we also needn't
  	 * requeue or dequeue this delayed node.
  	 */

  	refcount_dec(&delayed_node->refs);

  
  	return true;

  }

  void btrfs_readdir_put_delayed_items(struct inode *inode,
  				     struct list_head *ins_list,
  				     struct list_head *del_list)

  {
  	struct btrfs_delayed_item *curr, *next;
  
  	list_for_each_entry_safe(curr, next, ins_list, readdir_list) {
  		list_del(&curr->readdir_list);

  		if (refcount_dec_and_test(&curr->refs))

  			kfree(curr);
  	}
  
  	list_for_each_entry_safe(curr, next, del_list, readdir_list) {
  		list_del(&curr->readdir_list);

  		if (refcount_dec_and_test(&curr->refs))

  			kfree(curr);
  	}

  
  	/*
  	 * The VFS is going to do up_read(), so we need to downgrade back to a
  	 * read lock.
  	 */
  	downgrade_write(&inode->i_rwsem);

  }
  
  int btrfs_should_delete_dir_index(struct list_head *del_list,
  				  u64 index)
  {

  	struct btrfs_delayed_item *curr;
  	int ret = 0;

  	list_for_each_entry(curr, del_list, readdir_list) {

  		if (curr->key.offset > index)
  			break;

  		if (curr->key.offset == index) {
  			ret = 1;
  			break;
  		}

  	}

  	return ret;

  }
  
  /*
   * btrfs_readdir_delayed_dir_index - read dir info stored in the delayed tree
   *
   */

  int btrfs_readdir_delayed_dir_index(struct dir_context *ctx,

  				    struct list_head *ins_list)

  {
  	struct btrfs_dir_item *di;
  	struct btrfs_delayed_item *curr, *next;
  	struct btrfs_key location;
  	char *name;
  	int name_len;
  	int over = 0;
  	unsigned char d_type;
  
  	if (list_empty(ins_list))
  		return 0;
  
  	/*
  	 * Changing the data of the delayed item is impossible. So
  	 * we needn't lock them. And we have held i_mutex of the
  	 * directory, nobody can delete any directory indexes now.
  	 */
  	list_for_each_entry_safe(curr, next, ins_list, readdir_list) {
  		list_del(&curr->readdir_list);

  		if (curr->key.offset < ctx->pos) {

  			if (refcount_dec_and_test(&curr->refs))

  				kfree(curr);
  			continue;
  		}

  		ctx->pos = curr->key.offset;

  
  		di = (struct btrfs_dir_item *)curr->data;
  		name = (char *)(di + 1);

  		name_len = btrfs_stack_dir_name_len(di);

  		d_type = fs_ftype_to_dtype(di->type);

  		btrfs_disk_key_to_cpu(&location, &di->location);

  		over = !dir_emit(ctx, name, name_len,

  			       location.objectid, d_type);

  		if (refcount_dec_and_test(&curr->refs))

  			kfree(curr);
  
  		if (over)
  			return 1;

  		ctx->pos++;

  	}
  	return 0;
  }

  static void fill_stack_inode_item(struct btrfs_trans_handle *trans,
  				  struct btrfs_inode_item *inode_item,
  				  struct inode *inode)
  {

  	btrfs_set_stack_inode_uid(inode_item, i_uid_read(inode));
  	btrfs_set_stack_inode_gid(inode_item, i_gid_read(inode));

  	btrfs_set_stack_inode_size(inode_item, BTRFS_I(inode)->disk_i_size);
  	btrfs_set_stack_inode_mode(inode_item, inode->i_mode);
  	btrfs_set_stack_inode_nlink(inode_item, inode->i_nlink);
  	btrfs_set_stack_inode_nbytes(inode_item, inode_get_bytes(inode));
  	btrfs_set_stack_inode_generation(inode_item,
  					 BTRFS_I(inode)->generation);

  	btrfs_set_stack_inode_sequence(inode_item,
  				       inode_peek_iversion(inode));

  	btrfs_set_stack_inode_transid(inode_item, trans->transid);
  	btrfs_set_stack_inode_rdev(inode_item, inode->i_rdev);
  	btrfs_set_stack_inode_flags(inode_item, BTRFS_I(inode)->flags);

  	btrfs_set_stack_inode_block_group(inode_item, 0);

  	btrfs_set_stack_timespec_sec(&inode_item->atime,

  				     inode->i_atime.tv_sec);

  	btrfs_set_stack_timespec_nsec(&inode_item->atime,

  				      inode->i_atime.tv_nsec);

  	btrfs_set_stack_timespec_sec(&inode_item->mtime,

  				     inode->i_mtime.tv_sec);

  	btrfs_set_stack_timespec_nsec(&inode_item->mtime,

  				      inode->i_mtime.tv_nsec);

  	btrfs_set_stack_timespec_sec(&inode_item->ctime,

  				     inode->i_ctime.tv_sec);

  	btrfs_set_stack_timespec_nsec(&inode_item->ctime,

  				      inode->i_ctime.tv_nsec);

  
  	btrfs_set_stack_timespec_sec(&inode_item->otime,
  				     BTRFS_I(inode)->i_otime.tv_sec);
  	btrfs_set_stack_timespec_nsec(&inode_item->otime,
  				     BTRFS_I(inode)->i_otime.tv_nsec);

  }

  int btrfs_fill_inode(struct inode *inode, u32 *rdev)
  {
  	struct btrfs_delayed_node *delayed_node;
  	struct btrfs_inode_item *inode_item;

  	delayed_node = btrfs_get_delayed_node(BTRFS_I(inode));

  	if (!delayed_node)
  		return -ENOENT;
  
  	mutex_lock(&delayed_node->mutex);

  	if (!test_bit(BTRFS_DELAYED_NODE_INODE_DIRTY, &delayed_node->flags)) {

  		mutex_unlock(&delayed_node->mutex);
  		btrfs_release_delayed_node(delayed_node);
  		return -ENOENT;
  	}
  
  	inode_item = &delayed_node->inode_item;

  	i_uid_write(inode, btrfs_stack_inode_uid(inode_item));
  	i_gid_write(inode, btrfs_stack_inode_gid(inode_item));

  	btrfs_i_size_write(BTRFS_I(inode), btrfs_stack_inode_size(inode_item));

  	inode->i_mode = btrfs_stack_inode_mode(inode_item);

  	set_nlink(inode, btrfs_stack_inode_nlink(inode_item));

  	inode_set_bytes(inode, btrfs_stack_inode_nbytes(inode_item));
  	BTRFS_I(inode)->generation = btrfs_stack_inode_generation(inode_item);

          BTRFS_I(inode)->last_trans = btrfs_stack_inode_transid(inode_item);

  	inode_set_iversion_queried(inode,
  				   btrfs_stack_inode_sequence(inode_item));

  	inode->i_rdev = 0;
  	*rdev = btrfs_stack_inode_rdev(inode_item);
  	BTRFS_I(inode)->flags = btrfs_stack_inode_flags(inode_item);

  	inode->i_atime.tv_sec = btrfs_stack_timespec_sec(&inode_item->atime);
  	inode->i_atime.tv_nsec = btrfs_stack_timespec_nsec(&inode_item->atime);

  	inode->i_mtime.tv_sec = btrfs_stack_timespec_sec(&inode_item->mtime);
  	inode->i_mtime.tv_nsec = btrfs_stack_timespec_nsec(&inode_item->mtime);

  	inode->i_ctime.tv_sec = btrfs_stack_timespec_sec(&inode_item->ctime);
  	inode->i_ctime.tv_nsec = btrfs_stack_timespec_nsec(&inode_item->ctime);

  	BTRFS_I(inode)->i_otime.tv_sec =
  		btrfs_stack_timespec_sec(&inode_item->otime);
  	BTRFS_I(inode)->i_otime.tv_nsec =
  		btrfs_stack_timespec_nsec(&inode_item->otime);

  	inode->i_generation = BTRFS_I(inode)->generation;
  	BTRFS_I(inode)->index_cnt = (u64)-1;
  
  	mutex_unlock(&delayed_node->mutex);
  	btrfs_release_delayed_node(delayed_node);
  	return 0;
  }

  int btrfs_delayed_update_inode(struct btrfs_trans_handle *trans,
  			       struct btrfs_root *root, struct inode *inode)
  {
  	struct btrfs_delayed_node *delayed_node;

  	int ret = 0;

  	delayed_node = btrfs_get_or_create_delayed_node(BTRFS_I(inode));

  	if (IS_ERR(delayed_node))
  		return PTR_ERR(delayed_node);
  
  	mutex_lock(&delayed_node->mutex);

  	if (test_bit(BTRFS_DELAYED_NODE_INODE_DIRTY, &delayed_node->flags)) {

  		fill_stack_inode_item(trans, &delayed_node->inode_item, inode);
  		goto release_node;
  	}

  	ret = btrfs_delayed_inode_reserve_metadata(trans, root, BTRFS_I(inode),

  						   delayed_node);

  	if (ret)
  		goto release_node;

  
  	fill_stack_inode_item(trans, &delayed_node->inode_item, inode);

  	set_bit(BTRFS_DELAYED_NODE_INODE_DIRTY, &delayed_node->flags);

  	delayed_node->count++;
  	atomic_inc(&root->fs_info->delayed_root->items);
  release_node:
  	mutex_unlock(&delayed_node->mutex);
  	btrfs_release_delayed_node(delayed_node);
  	return ret;
  }

  int btrfs_delayed_delete_inode_ref(struct btrfs_inode *inode)

  {

  	struct btrfs_fs_info *fs_info = inode->root->fs_info;

  	struct btrfs_delayed_node *delayed_node;

  	/*
  	 * we don't do delayed inode updates during log recovery because it
  	 * leads to enospc problems.  This means we also can't do
  	 * delayed inode refs
  	 */

  	if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))

  		return -EAGAIN;

  	delayed_node = btrfs_get_or_create_delayed_node(inode);

  	if (IS_ERR(delayed_node))
  		return PTR_ERR(delayed_node);
  
  	/*
  	 * We don't reserve space for inode ref deletion is because:
  	 * - We ONLY do async inode ref deletion for the inode who has only
  	 *   one link(i_nlink == 1), it means there is only one inode ref.
  	 *   And in most case, the inode ref and the inode item are in the
  	 *   same leaf, and we will deal with them at the same time.
  	 *   Since we are sure we will reserve the space for the inode item,
  	 *   it is unnecessary to reserve space for inode ref deletion.
  	 * - If the inode ref and the inode item are not in the same leaf,
  	 *   We also needn't worry about enospc problem, because we reserve
  	 *   much more space for the inode update than it needs.
  	 * - At the worst, we can steal some space from the global reservation.
  	 *   It is very rare.
  	 */
  	mutex_lock(&delayed_node->mutex);
  	if (test_bit(BTRFS_DELAYED_NODE_DEL_IREF, &delayed_node->flags))
  		goto release_node;
  
  	set_bit(BTRFS_DELAYED_NODE_DEL_IREF, &delayed_node->flags);
  	delayed_node->count++;

  	atomic_inc(&fs_info->delayed_root->items);

  release_node:
  	mutex_unlock(&delayed_node->mutex);
  	btrfs_release_delayed_node(delayed_node);
  	return 0;
  }

  static void __btrfs_kill_delayed_node(struct btrfs_delayed_node *delayed_node)
  {
  	struct btrfs_root *root = delayed_node->root;

  	struct btrfs_fs_info *fs_info = root->fs_info;

  	struct btrfs_delayed_item *curr_item, *prev_item;
  
  	mutex_lock(&delayed_node->mutex);
  	curr_item = __btrfs_first_delayed_insertion_item(delayed_node);
  	while (curr_item) {

  		btrfs_delayed_item_release_metadata(root, curr_item);

  		prev_item = curr_item;
  		curr_item = __btrfs_next_delayed_item(prev_item);
  		btrfs_release_delayed_item(prev_item);
  	}
  
  	curr_item = __btrfs_first_delayed_deletion_item(delayed_node);
  	while (curr_item) {

  		btrfs_delayed_item_release_metadata(root, curr_item);

  		prev_item = curr_item;
  		curr_item = __btrfs_next_delayed_item(prev_item);
  		btrfs_release_delayed_item(prev_item);
  	}

  	if (test_bit(BTRFS_DELAYED_NODE_DEL_IREF, &delayed_node->flags))
  		btrfs_release_delayed_iref(delayed_node);

  	if (test_bit(BTRFS_DELAYED_NODE_INODE_DIRTY, &delayed_node->flags)) {

  		btrfs_delayed_inode_release_metadata(fs_info, delayed_node, false);

  		btrfs_release_delayed_inode(delayed_node);
  	}
  	mutex_unlock(&delayed_node->mutex);
  }

  void btrfs_kill_delayed_inode_items(struct btrfs_inode *inode)

  {
  	struct btrfs_delayed_node *delayed_node;

  	delayed_node = btrfs_get_delayed_node(inode);

  	if (!delayed_node)
  		return;
  
  	__btrfs_kill_delayed_node(delayed_node);
  	btrfs_release_delayed_node(delayed_node);
  }
  
  void btrfs_kill_all_delayed_nodes(struct btrfs_root *root)
  {
  	u64 inode_id = 0;
  	struct btrfs_delayed_node *delayed_nodes[8];
  	int i, n;
  
  	while (1) {
  		spin_lock(&root->inode_lock);
  		n = radix_tree_gang_lookup(&root->delayed_nodes_tree,
  					   (void **)delayed_nodes, inode_id,
  					   ARRAY_SIZE(delayed_nodes));
  		if (!n) {
  			spin_unlock(&root->inode_lock);
  			break;
  		}
  
  		inode_id = delayed_nodes[n - 1]->inode_id + 1;

  		for (i = 0; i < n; i++) {
  			/*
  			 * Don't increase refs in case the node is dead and
  			 * about to be removed from the tree in the loop below
  			 */
  			if (!refcount_inc_not_zero(&delayed_nodes[i]->refs))
  				delayed_nodes[i] = NULL;
  		}

  		spin_unlock(&root->inode_lock);
  
  		for (i = 0; i < n; i++) {

  			if (!delayed_nodes[i])
  				continue;

  			__btrfs_kill_delayed_node(delayed_nodes[i]);
  			btrfs_release_delayed_node(delayed_nodes[i]);
  		}
  	}
  }

  void btrfs_destroy_delayed_inodes(struct btrfs_fs_info *fs_info)

  {

  	struct btrfs_delayed_node *curr_node, *prev_node;

  	curr_node = btrfs_first_delayed_node(fs_info->delayed_root);

  	while (curr_node) {
  		__btrfs_kill_delayed_node(curr_node);
  
  		prev_node = curr_node;
  		curr_node = btrfs_next_delayed_node(curr_node);
  		btrfs_release_delayed_node(prev_node);
  	}
  }