/*
   * Copyright (C) 2009 Oracle.  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 <linux/sched.h>

  #include <linux/slab.h>

  #include <linux/sort.h>

  #include "ctree.h"
  #include "delayed-ref.h"
  #include "transaction.h"

  #include "qgroup.h"

  struct kmem_cache *btrfs_delayed_ref_head_cachep;
  struct kmem_cache *btrfs_delayed_tree_ref_cachep;
  struct kmem_cache *btrfs_delayed_data_ref_cachep;
  struct kmem_cache *btrfs_delayed_extent_op_cachep;

  /*
   * delayed back reference update tracking.  For subvolume trees
   * we queue up extent allocations and backref maintenance for
   * delayed processing.   This avoids deep call chains where we
   * add extents in the middle of btrfs_search_slot, and it allows
   * us to buffer up frequently modified backrefs in an rb tree instead
   * of hammering updates on the extent allocation tree.

   */
  
  /*

   * compare two delayed tree backrefs with same bytenr and type
   */
  static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref2,

  			  struct btrfs_delayed_tree_ref *ref1, int type)

  {

  	if (type == BTRFS_TREE_BLOCK_REF_KEY) {
  		if (ref1->root < ref2->root)
  			return -1;
  		if (ref1->root > ref2->root)
  			return 1;
  	} else {
  		if (ref1->parent < ref2->parent)
  			return -1;
  		if (ref1->parent > ref2->parent)
  			return 1;
  	}

  	return 0;
  }
  
  /*
   * compare two delayed data backrefs with same bytenr and type

   */

  static int comp_data_refs(struct btrfs_delayed_data_ref *ref2,
  			  struct btrfs_delayed_data_ref *ref1)

  {

  	if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
  		if (ref1->root < ref2->root)
  			return -1;
  		if (ref1->root > ref2->root)
  			return 1;
  		if (ref1->objectid < ref2->objectid)
  			return -1;
  		if (ref1->objectid > ref2->objectid)
  			return 1;
  		if (ref1->offset < ref2->offset)
  			return -1;
  		if (ref1->offset > ref2->offset)
  			return 1;
  	} else {
  		if (ref1->parent < ref2->parent)
  			return -1;
  		if (ref1->parent > ref2->parent)
  			return 1;
  	}
  	return 0;
  }

  /* insert a new ref to head ref rbtree */
  static struct btrfs_delayed_ref_head *htree_insert(struct rb_root *root,
  						   struct rb_node *node)
  {
  	struct rb_node **p = &root->rb_node;
  	struct rb_node *parent_node = NULL;
  	struct btrfs_delayed_ref_head *entry;
  	struct btrfs_delayed_ref_head *ins;
  	u64 bytenr;
  
  	ins = rb_entry(node, struct btrfs_delayed_ref_head, href_node);
  	bytenr = ins->node.bytenr;
  	while (*p) {
  		parent_node = *p;
  		entry = rb_entry(parent_node, struct btrfs_delayed_ref_head,
  				 href_node);
  
  		if (bytenr < entry->node.bytenr)
  			p = &(*p)->rb_left;
  		else if (bytenr > entry->node.bytenr)
  			p = &(*p)->rb_right;
  		else
  			return entry;
  	}
  
  	rb_link_node(node, parent_node, p);
  	rb_insert_color(node, root);
  	return NULL;
  }

  /*

   * find an head entry based on bytenr. This returns the delayed ref

   * head if it was able to find one, or NULL if nothing was in that spot.
   * If return_bigger is given, the next bigger entry is returned if no exact
   * match is found.

   */

  static struct btrfs_delayed_ref_head *
  find_ref_head(struct rb_root *root, u64 bytenr,

  	      int return_bigger)

  {

  	struct rb_node *n;

  	struct btrfs_delayed_ref_head *entry;

  	n = root->rb_node;
  	entry = NULL;

  	while (n) {

  		entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);

  		if (bytenr < entry->node.bytenr)

  			n = n->rb_left;

  		else if (bytenr > entry->node.bytenr)

  			n = n->rb_right;
  		else
  			return entry;
  	}

  	if (entry && return_bigger) {

  		if (bytenr > entry->node.bytenr) {

  			n = rb_next(&entry->href_node);

  			if (!n)
  				n = rb_first(root);

  			entry = rb_entry(n, struct btrfs_delayed_ref_head,
  					 href_node);

  			return entry;

  		}
  		return entry;
  	}

  	return NULL;
  }

  int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
  			   struct btrfs_delayed_ref_head *head)

  {

  	struct btrfs_delayed_ref_root *delayed_refs;
  
  	delayed_refs = &trans->transaction->delayed_refs;
  	assert_spin_locked(&delayed_refs->lock);
  	if (mutex_trylock(&head->mutex))
  		return 0;
  
  	atomic_inc(&head->node.refs);
  	spin_unlock(&delayed_refs->lock);
  
  	mutex_lock(&head->mutex);
  	spin_lock(&delayed_refs->lock);
  	if (!head->node.in_tree) {
  		mutex_unlock(&head->mutex);
  		btrfs_put_delayed_ref(&head->node);
  		return -EAGAIN;
  	}
  	btrfs_put_delayed_ref(&head->node);
  	return 0;
  }

  static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,

  				    struct btrfs_delayed_ref_root *delayed_refs,

  				    struct btrfs_delayed_ref_head *head,

  				    struct btrfs_delayed_ref_node *ref)
  {

  	if (btrfs_delayed_ref_is_head(ref)) {

  		head = btrfs_delayed_node_to_head(ref);
  		rb_erase(&head->href_node, &delayed_refs->href_root);

  	} else {
  		assert_spin_locked(&head->lock);

  		list_del(&ref->list);

  	}

  	ref->in_tree = 0;
  	btrfs_put_delayed_ref(ref);

  	atomic_dec(&delayed_refs->num_entries);

  	if (trans->delayed_ref_updates)
  		trans->delayed_ref_updates--;
  }

  static bool merge_ref(struct btrfs_trans_handle *trans,
  		      struct btrfs_delayed_ref_root *delayed_refs,
  		      struct btrfs_delayed_ref_head *head,
  		      struct btrfs_delayed_ref_node *ref,
  		      u64 seq)
  {
  	struct btrfs_delayed_ref_node *next;
  	bool done = false;
  
  	next = list_first_entry(&head->ref_list, struct btrfs_delayed_ref_node,
  				list);
  	while (!done && &next->list != &head->ref_list) {
  		int mod;
  		struct btrfs_delayed_ref_node *next2;
  
  		next2 = list_next_entry(next, list);
  
  		if (next == ref)
  			goto next;
  
  		if (seq && next->seq >= seq)
  			goto next;

  		if (next->type != ref->type)

  			goto next;
  
  		if ((ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
  		     ref->type == BTRFS_SHARED_BLOCK_REF_KEY) &&
  		    comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref),
  				   btrfs_delayed_node_to_tree_ref(next),
  				   ref->type))
  			goto next;
  		if ((ref->type == BTRFS_EXTENT_DATA_REF_KEY ||
  		     ref->type == BTRFS_SHARED_DATA_REF_KEY) &&
  		    comp_data_refs(btrfs_delayed_node_to_data_ref(ref),
  				   btrfs_delayed_node_to_data_ref(next)))
  			goto next;
  
  		if (ref->action == next->action) {
  			mod = next->ref_mod;
  		} else {
  			if (ref->ref_mod < next->ref_mod) {
  				swap(ref, next);
  				done = true;
  			}
  			mod = -next->ref_mod;
  		}
  
  		drop_delayed_ref(trans, delayed_refs, head, next);
  		ref->ref_mod += mod;
  		if (ref->ref_mod == 0) {
  			drop_delayed_ref(trans, delayed_refs, head, ref);
  			done = true;
  		} else {
  			/*
  			 * Can't have multiples of the same ref on a tree block.
  			 */
  			WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
  				ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
  		}
  next:
  		next = next2;
  	}
  
  	return done;
  }
  
  void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
  			      struct btrfs_fs_info *fs_info,
  			      struct btrfs_delayed_ref_root *delayed_refs,
  			      struct btrfs_delayed_ref_head *head)
  {
  	struct btrfs_delayed_ref_node *ref;
  	u64 seq = 0;
  
  	assert_spin_locked(&head->lock);
  
  	if (list_empty(&head->ref_list))
  		return;
  
  	/* We don't have too many refs to merge for data. */
  	if (head->is_data)
  		return;
  
  	spin_lock(&fs_info->tree_mod_seq_lock);
  	if (!list_empty(&fs_info->tree_mod_seq_list)) {
  		struct seq_list *elem;
  
  		elem = list_first_entry(&fs_info->tree_mod_seq_list,
  					struct seq_list, list);
  		seq = elem->seq;
  	}
  	spin_unlock(&fs_info->tree_mod_seq_lock);
  
  	ref = list_first_entry(&head->ref_list, struct btrfs_delayed_ref_node,
  			       list);
  	while (&ref->list != &head->ref_list) {
  		if (seq && ref->seq >= seq)
  			goto next;
  
  		if (merge_ref(trans, delayed_refs, head, ref, seq)) {
  			if (list_empty(&head->ref_list))
  				break;
  			ref = list_first_entry(&head->ref_list,
  					       struct btrfs_delayed_ref_node,
  					       list);
  			continue;
  		}
  next:
  		ref = list_next_entry(ref, list);
  	}
  }

  int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
  			    struct btrfs_delayed_ref_root *delayed_refs,

  			    u64 seq)
  {
  	struct seq_list *elem;

  	int ret = 0;
  
  	spin_lock(&fs_info->tree_mod_seq_lock);
  	if (!list_empty(&fs_info->tree_mod_seq_list)) {
  		elem = list_first_entry(&fs_info->tree_mod_seq_list,
  					struct seq_list, list);
  		if (seq >= elem->seq) {

  			btrfs_debug(fs_info,
  				"holding back delayed_ref %#x.%x, lowest is %#x.%x (%p)",
  				(u32)(seq >> 32), (u32)seq,
  				(u32)(elem->seq >> 32), (u32)elem->seq,
  				delayed_refs);

  			ret = 1;
  		}

  	}

  
  	spin_unlock(&fs_info->tree_mod_seq_lock);
  	return ret;

  }

  struct btrfs_delayed_ref_head *
  btrfs_select_ref_head(struct btrfs_trans_handle *trans)

  {

  	struct btrfs_delayed_ref_root *delayed_refs;

  	struct btrfs_delayed_ref_head *head;
  	u64 start;
  	bool loop = false;

  	delayed_refs = &trans->transaction->delayed_refs;

  again:

  	start = delayed_refs->run_delayed_start;

  	head = find_ref_head(&delayed_refs->href_root, start, 1);

  	if (!head && !loop) {
  		delayed_refs->run_delayed_start = 0;

  		start = 0;

  		loop = true;

  		head = find_ref_head(&delayed_refs->href_root, start, 1);

  		if (!head)
  			return NULL;
  	} else if (!head && loop) {
  		return NULL;

  	}

  	while (head->processing) {
  		struct rb_node *node;
  
  		node = rb_next(&head->href_node);
  		if (!node) {
  			if (loop)
  				return NULL;
  			delayed_refs->run_delayed_start = 0;
  			start = 0;
  			loop = true;
  			goto again;
  		}
  		head = rb_entry(node, struct btrfs_delayed_ref_head,
  				href_node);
  	}

  	head->processing = 1;
  	WARN_ON(delayed_refs->num_heads_ready == 0);
  	delayed_refs->num_heads_ready--;
  	delayed_refs->run_delayed_start = head->node.bytenr +
  		head->node.num_bytes;
  	return head;

  }

  /*

   * Helper to insert the ref_node to the tail or merge with tail.
   *
   * Return 0 for insert.
   * Return >0 for merge.
   */
  static int
  add_delayed_ref_tail_merge(struct btrfs_trans_handle *trans,
  			   struct btrfs_delayed_ref_root *root,
  			   struct btrfs_delayed_ref_head *href,
  			   struct btrfs_delayed_ref_node *ref)
  {
  	struct btrfs_delayed_ref_node *exist;
  	int mod;
  	int ret = 0;
  
  	spin_lock(&href->lock);
  	/* Check whether we can merge the tail node with ref */
  	if (list_empty(&href->ref_list))
  		goto add_tail;
  	exist = list_entry(href->ref_list.prev, struct btrfs_delayed_ref_node,
  			   list);
  	/* No need to compare bytenr nor is_head */

  	if (exist->type != ref->type || exist->seq != ref->seq)

  		goto add_tail;
  
  	if ((exist->type == BTRFS_TREE_BLOCK_REF_KEY ||
  	     exist->type == BTRFS_SHARED_BLOCK_REF_KEY) &&
  	    comp_tree_refs(btrfs_delayed_node_to_tree_ref(exist),
  			   btrfs_delayed_node_to_tree_ref(ref),
  			   ref->type))
  		goto add_tail;
  	if ((exist->type == BTRFS_EXTENT_DATA_REF_KEY ||
  	     exist->type == BTRFS_SHARED_DATA_REF_KEY) &&
  	    comp_data_refs(btrfs_delayed_node_to_data_ref(exist),
  			   btrfs_delayed_node_to_data_ref(ref)))
  		goto add_tail;
  
  	/* Now we are sure we can merge */
  	ret = 1;
  	if (exist->action == ref->action) {
  		mod = ref->ref_mod;
  	} else {
  		/* Need to change action */
  		if (exist->ref_mod < ref->ref_mod) {
  			exist->action = ref->action;
  			mod = -exist->ref_mod;
  			exist->ref_mod = ref->ref_mod;
  		} else
  			mod = -ref->ref_mod;
  	}
  	exist->ref_mod += mod;
  
  	/* remove existing tail if its ref_mod is zero */
  	if (exist->ref_mod == 0)
  		drop_delayed_ref(trans, root, href, exist);
  	spin_unlock(&href->lock);
  	return ret;
  
  add_tail:
  	list_add_tail(&ref->list, &href->ref_list);
  	atomic_inc(&root->num_entries);
  	trans->delayed_ref_updates++;
  	spin_unlock(&href->lock);
  	return ret;
  }
  
  /*

   * helper function to update the accounting in the head ref
   * existing and update must have the same bytenr
   */
  static noinline void

  update_existing_head_ref(struct btrfs_delayed_ref_root *delayed_refs,
  			 struct btrfs_delayed_ref_node *existing,

  			 struct btrfs_delayed_ref_node *update)
  {
  	struct btrfs_delayed_ref_head *existing_ref;
  	struct btrfs_delayed_ref_head *ref;

  	int old_ref_mod;

  
  	existing_ref = btrfs_delayed_node_to_head(existing);
  	ref = btrfs_delayed_node_to_head(update);

  	BUG_ON(existing_ref->is_data != ref->is_data);

  	spin_lock(&existing_ref->lock);

  	if (ref->must_insert_reserved) {
  		/* if the extent was freed and then
  		 * reallocated before the delayed ref
  		 * entries were processed, we can end up
  		 * with an existing head ref without
  		 * the must_insert_reserved flag set.
  		 * Set it again here
  		 */
  		existing_ref->must_insert_reserved = ref->must_insert_reserved;
  
  		/*
  		 * update the num_bytes so we make sure the accounting
  		 * is done correctly
  		 */
  		existing->num_bytes = update->num_bytes;
  
  	}

  	if (ref->extent_op) {
  		if (!existing_ref->extent_op) {
  			existing_ref->extent_op = ref->extent_op;
  		} else {
  			if (ref->extent_op->update_key) {
  				memcpy(&existing_ref->extent_op->key,
  				       &ref->extent_op->key,
  				       sizeof(ref->extent_op->key));

  				existing_ref->extent_op->update_key = true;

  			}
  			if (ref->extent_op->update_flags) {
  				existing_ref->extent_op->flags_to_set |=
  					ref->extent_op->flags_to_set;

  				existing_ref->extent_op->update_flags = true;

  			}

  			btrfs_free_delayed_extent_op(ref->extent_op);

  		}
  	}

  	/*

  	 * update the reference mod on the head to reflect this new operation,
  	 * only need the lock for this case cause we could be processing it
  	 * currently, for refs we just added we know we're a-ok.

  	 */

  	old_ref_mod = existing_ref->total_ref_mod;

  	existing->ref_mod += update->ref_mod;

  	existing_ref->total_ref_mod += update->ref_mod;
  
  	/*
  	 * If we are going to from a positive ref mod to a negative or vice
  	 * versa we need to make sure to adjust pending_csums accordingly.
  	 */
  	if (existing_ref->is_data) {
  		if (existing_ref->total_ref_mod >= 0 && old_ref_mod < 0)
  			delayed_refs->pending_csums -= existing->num_bytes;
  		if (existing_ref->total_ref_mod < 0 && old_ref_mod >= 0)
  			delayed_refs->pending_csums += existing->num_bytes;
  	}

  	spin_unlock(&existing_ref->lock);

  }
  
  /*

   * helper function to actually insert a head node into the rbtree.

   * this does all the dirty work in terms of maintaining the correct

   * overall modification count.

   */

  static noinline struct btrfs_delayed_ref_head *
  add_delayed_ref_head(struct btrfs_fs_info *fs_info,
  		     struct btrfs_trans_handle *trans,

  		     struct btrfs_delayed_ref_node *ref,
  		     struct btrfs_qgroup_extent_record *qrecord,

  		     u64 bytenr, u64 num_bytes, u64 ref_root, u64 reserved,
  		     int action, int is_data)

  {

  	struct btrfs_delayed_ref_head *existing;

  	struct btrfs_delayed_ref_head *head_ref = NULL;

  	struct btrfs_delayed_ref_root *delayed_refs;
  	int count_mod = 1;
  	int must_insert_reserved = 0;

  	/* If reserved is provided, it must be a data extent. */
  	BUG_ON(!is_data && reserved);

  	/*
  	 * the head node stores the sum of all the mods, so dropping a ref
  	 * should drop the sum in the head node by one.
  	 */

  	if (action == BTRFS_UPDATE_DELAYED_HEAD)
  		count_mod = 0;
  	else if (action == BTRFS_DROP_DELAYED_REF)
  		count_mod = -1;

  
  	/*
  	 * BTRFS_ADD_DELAYED_EXTENT means that we need to update
  	 * the reserved accounting when the extent is finally added, or
  	 * if a later modification deletes the delayed ref without ever
  	 * inserting the extent into the extent allocation tree.
  	 * ref->must_insert_reserved is the flag used to record
  	 * that accounting mods are required.
  	 *
  	 * Once we record must_insert_reserved, switch the action to
  	 * BTRFS_ADD_DELAYED_REF because other special casing is not required.
  	 */

  	if (action == BTRFS_ADD_DELAYED_EXTENT)

  		must_insert_reserved = 1;

  	else

  		must_insert_reserved = 0;

  
  	delayed_refs = &trans->transaction->delayed_refs;
  
  	/* first set the basic ref node struct up */
  	atomic_set(&ref->refs, 1);
  	ref->bytenr = bytenr;

  	ref->num_bytes = num_bytes;

  	ref->ref_mod = count_mod;

  	ref->type  = 0;
  	ref->action  = 0;
  	ref->is_head = 1;

  	ref->in_tree = 1;

  	ref->seq = 0;

  
  	head_ref = btrfs_delayed_node_to_head(ref);
  	head_ref->must_insert_reserved = must_insert_reserved;
  	head_ref->is_data = is_data;

  	INIT_LIST_HEAD(&head_ref->ref_list);

  	head_ref->processing = 0;

  	head_ref->total_ref_mod = count_mod;

  	head_ref->qgroup_reserved = 0;
  	head_ref->qgroup_ref_root = 0;

  	/* Record qgroup extent info if provided */
  	if (qrecord) {

  		if (ref_root && reserved) {
  			head_ref->qgroup_ref_root = ref_root;
  			head_ref->qgroup_reserved = reserved;
  		}

  		qrecord->bytenr = bytenr;
  		qrecord->num_bytes = num_bytes;
  		qrecord->old_roots = NULL;

  		if(btrfs_qgroup_insert_dirty_extent_nolock(fs_info,
  					delayed_refs, qrecord))

  			kfree(qrecord);
  	}

  	spin_lock_init(&head_ref->lock);

  	mutex_init(&head_ref->mutex);

  	trace_add_delayed_ref_head(fs_info, ref, head_ref, action);

  	existing = htree_insert(&delayed_refs->href_root,
  				&head_ref->href_node);

  	if (existing) {

  		WARN_ON(ref_root && reserved && existing->qgroup_ref_root
  			&& existing->qgroup_reserved);

  		update_existing_head_ref(delayed_refs, &existing->node, ref);

  		/*
  		 * we've updated the existing ref, free the newly
  		 * allocated ref
  		 */

  		kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);

  		head_ref = existing;

  	} else {

  		if (is_data && count_mod < 0)
  			delayed_refs->pending_csums += num_bytes;

  		delayed_refs->num_heads++;
  		delayed_refs->num_heads_ready++;

  		atomic_inc(&delayed_refs->num_entries);

  		trans->delayed_ref_updates++;
  	}

  	return head_ref;

  }
  
  /*
   * helper to insert a delayed tree ref into the rbtree.
   */

  static noinline void
  add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
  		     struct btrfs_trans_handle *trans,
  		     struct btrfs_delayed_ref_head *head_ref,
  		     struct btrfs_delayed_ref_node *ref, u64 bytenr,
  		     u64 num_bytes, u64 parent, u64 ref_root, int level,

  		     int action)

  {

  	struct btrfs_delayed_tree_ref *full_ref;
  	struct btrfs_delayed_ref_root *delayed_refs;

  	u64 seq = 0;

  	int ret;

  
  	if (action == BTRFS_ADD_DELAYED_EXTENT)
  		action = BTRFS_ADD_DELAYED_REF;

  	if (is_fstree(ref_root))
  		seq = atomic64_read(&fs_info->tree_mod_seq);

  	delayed_refs = &trans->transaction->delayed_refs;
  
  	/* first set the basic ref node struct up */
  	atomic_set(&ref->refs, 1);
  	ref->bytenr = bytenr;

  	ref->num_bytes = num_bytes;

  	ref->ref_mod = 1;
  	ref->action = action;
  	ref->is_head = 0;
  	ref->in_tree = 1;

  	ref->seq = seq;

  	full_ref = btrfs_delayed_node_to_tree_ref(ref);

  	full_ref->parent = parent;
  	full_ref->root = ref_root;
  	if (parent)

  		ref->type = BTRFS_SHARED_BLOCK_REF_KEY;

  	else

  		ref->type = BTRFS_TREE_BLOCK_REF_KEY;

  	full_ref->level = level;

  	trace_add_delayed_tree_ref(fs_info, ref, full_ref, action);

  	ret = add_delayed_ref_tail_merge(trans, delayed_refs, head_ref, ref);
  
  	/*
  	 * XXX: memory should be freed at the same level allocated.
  	 * But bad practice is anywhere... Follow it now. Need cleanup.
  	 */
  	if (ret > 0)

  		kmem_cache_free(btrfs_delayed_tree_ref_cachep, full_ref);

  }
  
  /*
   * helper to insert a delayed data ref into the rbtree.
   */

  static noinline void
  add_delayed_data_ref(struct btrfs_fs_info *fs_info,
  		     struct btrfs_trans_handle *trans,
  		     struct btrfs_delayed_ref_head *head_ref,
  		     struct btrfs_delayed_ref_node *ref, u64 bytenr,
  		     u64 num_bytes, u64 parent, u64 ref_root, u64 owner,

  		     u64 offset, int action)

  {

  	struct btrfs_delayed_data_ref *full_ref;
  	struct btrfs_delayed_ref_root *delayed_refs;

  	u64 seq = 0;

  	int ret;

  
  	if (action == BTRFS_ADD_DELAYED_EXTENT)
  		action = BTRFS_ADD_DELAYED_REF;
  
  	delayed_refs = &trans->transaction->delayed_refs;

  	if (is_fstree(ref_root))
  		seq = atomic64_read(&fs_info->tree_mod_seq);

  	/* first set the basic ref node struct up */
  	atomic_set(&ref->refs, 1);
  	ref->bytenr = bytenr;
  	ref->num_bytes = num_bytes;
  	ref->ref_mod = 1;
  	ref->action = action;
  	ref->is_head = 0;
  	ref->in_tree = 1;

  	ref->seq = seq;

  	full_ref = btrfs_delayed_node_to_data_ref(ref);

  	full_ref->parent = parent;
  	full_ref->root = ref_root;
  	if (parent)

  		ref->type = BTRFS_SHARED_DATA_REF_KEY;

  	else

  		ref->type = BTRFS_EXTENT_DATA_REF_KEY;

  	full_ref->objectid = owner;
  	full_ref->offset = offset;

  	trace_add_delayed_data_ref(fs_info, ref, full_ref, action);

  	ret = add_delayed_ref_tail_merge(trans, delayed_refs, head_ref, ref);
  
  	if (ret > 0)

  		kmem_cache_free(btrfs_delayed_data_ref_cachep, full_ref);

  }
  
  /*

   * add a delayed tree ref.  This does all of the accounting required

   * to make sure the delayed ref is eventually processed before this
   * transaction commits.
   */

  int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
  			       struct btrfs_trans_handle *trans,

  			       u64 bytenr, u64 num_bytes, u64 parent,
  			       u64 ref_root,  int level, int action,

  			       struct btrfs_delayed_extent_op *extent_op)

  {

  	struct btrfs_delayed_tree_ref *ref;

  	struct btrfs_delayed_ref_head *head_ref;
  	struct btrfs_delayed_ref_root *delayed_refs;

  	struct btrfs_qgroup_extent_record *record = NULL;

  	BUG_ON(extent_op && extent_op->is_data);

  	ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);

  	if (!ref)
  		return -ENOMEM;

  	head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);

  	if (!head_ref)
  		goto free_ref;

  	if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
  	    is_fstree(ref_root)) {

  		record = kmalloc(sizeof(*record), GFP_NOFS);

  		if (!record)
  			goto free_head_ref;

  	}

  	head_ref->extent_op = extent_op;
  
  	delayed_refs = &trans->transaction->delayed_refs;
  	spin_lock(&delayed_refs->lock);

  	/*

  	 * insert both the head node and the new ref without dropping
  	 * the spin lock

  	 */

  	head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node, record,

  					bytenr, num_bytes, 0, 0, action, 0);

  	add_delayed_tree_ref(fs_info, trans, head_ref, &ref->node, bytenr,

  			     num_bytes, parent, ref_root, level, action);

  	spin_unlock(&delayed_refs->lock);

  	return 0;

  
  free_head_ref:
  	kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
  free_ref:
  	kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
  
  	return -ENOMEM;

  }
  
  /*
   * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
   */

  int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
  			       struct btrfs_trans_handle *trans,

  			       u64 bytenr, u64 num_bytes,
  			       u64 parent, u64 ref_root,

  			       u64 owner, u64 offset, u64 reserved, int action,

  			       struct btrfs_delayed_extent_op *extent_op)

  {
  	struct btrfs_delayed_data_ref *ref;
  	struct btrfs_delayed_ref_head *head_ref;
  	struct btrfs_delayed_ref_root *delayed_refs;

  	struct btrfs_qgroup_extent_record *record = NULL;

  
  	BUG_ON(extent_op && !extent_op->is_data);

  	ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);

  	if (!ref)
  		return -ENOMEM;

  	head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);

  	if (!head_ref) {

  		kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);

  		return -ENOMEM;
  	}

  	if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
  	    is_fstree(ref_root)) {

  		record = kmalloc(sizeof(*record), GFP_NOFS);
  		if (!record) {
  			kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
  			kmem_cache_free(btrfs_delayed_ref_head_cachep,
  					head_ref);
  			return -ENOMEM;
  		}
  	}

  	head_ref->extent_op = extent_op;

  	delayed_refs = &trans->transaction->delayed_refs;
  	spin_lock(&delayed_refs->lock);
  
  	/*
  	 * insert both the head node and the new ref without dropping
  	 * the spin lock
  	 */

  	head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node, record,

  					bytenr, num_bytes, ref_root, reserved,
  					action, 1);

  	add_delayed_data_ref(fs_info, trans, head_ref, &ref->node, bytenr,

  				   num_bytes, parent, ref_root, owner, offset,

  				   action);

  	spin_unlock(&delayed_refs->lock);

  	return 0;
  }

  int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
  				struct btrfs_trans_handle *trans,

  				u64 bytenr, u64 num_bytes,
  				struct btrfs_delayed_extent_op *extent_op)
  {
  	struct btrfs_delayed_ref_head *head_ref;
  	struct btrfs_delayed_ref_root *delayed_refs;

  	head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);

  	if (!head_ref)
  		return -ENOMEM;
  
  	head_ref->extent_op = extent_op;
  
  	delayed_refs = &trans->transaction->delayed_refs;
  	spin_lock(&delayed_refs->lock);

  	add_delayed_ref_head(fs_info, trans, &head_ref->node, NULL, bytenr,

  			     num_bytes, 0, 0, BTRFS_UPDATE_DELAYED_HEAD,

  			     extent_op->is_data);

  	spin_unlock(&delayed_refs->lock);
  	return 0;
  }
  
  /*

   * this does a simple search for the head node for a given extent.
   * It must be called with the delayed ref spinlock held, and it returns
   * the head node if any where found, or NULL if not.
   */
  struct btrfs_delayed_ref_head *
  btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
  {

  	struct btrfs_delayed_ref_root *delayed_refs;
  
  	delayed_refs = &trans->transaction->delayed_refs;

  	return find_ref_head(&delayed_refs->href_root, bytenr, 0);

  }

  
  void btrfs_delayed_ref_exit(void)
  {

  	kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
  	kmem_cache_destroy(btrfs_delayed_tree_ref_cachep);
  	kmem_cache_destroy(btrfs_delayed_data_ref_cachep);
  	kmem_cache_destroy(btrfs_delayed_extent_op_cachep);

  }
  
  int btrfs_delayed_ref_init(void)
  {
  	btrfs_delayed_ref_head_cachep = kmem_cache_create(
  				"btrfs_delayed_ref_head",
  				sizeof(struct btrfs_delayed_ref_head), 0,

  				SLAB_MEM_SPREAD, NULL);

  	if (!btrfs_delayed_ref_head_cachep)
  		goto fail;
  
  	btrfs_delayed_tree_ref_cachep = kmem_cache_create(
  				"btrfs_delayed_tree_ref",
  				sizeof(struct btrfs_delayed_tree_ref), 0,

  				SLAB_MEM_SPREAD, NULL);

  	if (!btrfs_delayed_tree_ref_cachep)
  		goto fail;
  
  	btrfs_delayed_data_ref_cachep = kmem_cache_create(
  				"btrfs_delayed_data_ref",
  				sizeof(struct btrfs_delayed_data_ref), 0,

  				SLAB_MEM_SPREAD, NULL);

  	if (!btrfs_delayed_data_ref_cachep)
  		goto fail;
  
  	btrfs_delayed_extent_op_cachep = kmem_cache_create(
  				"btrfs_delayed_extent_op",
  				sizeof(struct btrfs_delayed_extent_op), 0,

  				SLAB_MEM_SPREAD, NULL);

  	if (!btrfs_delayed_extent_op_cachep)
  		goto fail;
  
  	return 0;
  fail:
  	btrfs_delayed_ref_exit();
  	return -ENOMEM;
  }