btrfs: Use init_delayed_ref_head in add_delayed_ref_head

{

	struct btrfs_delayed_ref_head *existing;

	struct btrfs_delayed_ref_root *delayed_refs;

	int count_mod = 1;

	int must_insert_reserved = 0;

	int qrecord_inserted = 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;

	refcount_set(&head_ref->refs, 1);

	head_ref->bytenr = bytenr;

	head_ref->num_bytes = num_bytes;

	head_ref->ref_mod = count_mod;

	head_ref->must_insert_reserved = must_insert_reserved;

	head_ref->is_data = is_data;

	head_ref->is_system = is_system;

	head_ref->ref_tree = RB_ROOT;

	INIT_LIST_HEAD(&head_ref->ref_add_list);

	RB_CLEAR_NODE(&head_ref->href_node);

	head_ref->processing = 0;

	head_ref->total_ref_mod = count_mod;

	head_ref->qgroup_reserved = 0;

	head_ref->qgroup_ref_root = 0;

	spin_lock_init(&head_ref->lock);

	mutex_init(&head_ref->mutex);

	init_delayed_ref_head(head_ref, qrecord, bytenr, num_bytes, ref_root,

			      reserved, action, is_data, is_system);

	/* 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_trace_extent_nolock(trans->fs_info,

					delayed_refs, qrecord))

			kfree(qrecord);

	} else {

		if (old_ref_mod)

			*old_ref_mod = 0;

		if (is_data && count_mod < 0)

		if (is_data && head_ref->ref_mod < 0)

			delayed_refs->pending_csums += num_bytes;

		delayed_refs->num_heads++;

		delayed_refs->num_heads_ready++;