683  * Return true if the ref was merged into an existing one (and therefore can be
728 	/* remove existing tail if its ref_mod is zero */  in insert_delayed_ref()
737  * existing and update must have the same bytenr
740 			 struct btrfs_delayed_ref_head *existing,  in update_existing_head_ref()  argument
748 	BUG_ON(existing->is_data != update->is_data);  in update_existing_head_ref()
750 	spin_lock(&existing->lock);  in update_existing_head_ref()
757 	if (!existing->owning_root)  in update_existing_head_ref()
758 		existing->owning_root = update->owning_root;  in update_existing_head_ref()
764 		 * with an existing head ref without  in update_existing_head_ref()
768 		existing->must_insert_reserved = update->must_insert_reserved;  in update_existing_head_ref()
769 		existing->owning_root = update->owning_root;  in update_existing_head_ref()
775 		existing->num_bytes = update->num_bytes;  in update_existing_head_ref()
780 		if (!existing->extent_op) {  in update_existing_head_ref()
781 			existing->extent_op = update->extent_op;  in update_existing_head_ref()
784 				memcpy(&existing->extent_op->key,  in update_existing_head_ref()
787 				existing->extent_op->update_key = true;  in update_existing_head_ref()
790 				existing->extent_op->flags_to_set |=  in update_existing_head_ref()
792 				existing->extent_op->update_flags = true;  in update_existing_head_ref()
802 	old_ref_mod = existing->total_ref_mod;  in update_existing_head_ref()
803 	existing->ref_mod += update->ref_mod;  in update_existing_head_ref()
804 	existing->total_ref_mod += update->ref_mod;  in update_existing_head_ref()
812 	if (existing->is_data) {  in update_existing_head_ref()
815 						   existing->num_bytes);  in update_existing_head_ref()
817 		if (existing->total_ref_mod >= 0 && old_ref_mod < 0) {  in update_existing_head_ref()
818 			delayed_refs->pending_csums -= existing->num_bytes;  in update_existing_head_ref()
821 		if (existing->total_ref_mod < 0 && old_ref_mod >= 0) {  in update_existing_head_ref()
822 			delayed_refs->pending_csums += existing->num_bytes;  in update_existing_head_ref()
827 	spin_unlock(&existing->lock);  in update_existing_head_ref()
909 	struct btrfs_delayed_ref_head *existing;  in add_delayed_ref_head()  local
926 	existing = htree_insert(&delayed_refs->href_root,  in add_delayed_ref_head()
928 	if (existing) {  in add_delayed_ref_head()
929 		update_existing_head_ref(trans, existing, head_ref);  in add_delayed_ref_head()
931 		 * we've updated the existing ref, free the newly  in add_delayed_ref_head()
935 		head_ref = existing;  in add_delayed_ref_head()