582  * Return true if the ref was merged into an existing one (and therefore can be
626 	/* remove existing tail if its ref_mod is zero */  in insert_delayed_ref()
635  * existing and update must have the same bytenr
638 			 struct btrfs_delayed_ref_head *existing,  in update_existing_head_ref()  argument
646 	BUG_ON(existing->is_data != update->is_data);  in update_existing_head_ref()
648 	spin_lock(&existing->lock);  in update_existing_head_ref()
655 	if (!existing->owning_root)  in update_existing_head_ref()
656 		existing->owning_root = update->owning_root;  in update_existing_head_ref()
662 		 * with an existing head ref without  in update_existing_head_ref()
666 		existing->must_insert_reserved = update->must_insert_reserved;  in update_existing_head_ref()
667 		existing->owning_root = update->owning_root;  in update_existing_head_ref()
673 		existing->num_bytes = update->num_bytes;  in update_existing_head_ref()
678 		if (!existing->extent_op) {  in update_existing_head_ref()
679 			existing->extent_op = update->extent_op;  in update_existing_head_ref()
682 				memcpy(&existing->extent_op->key,  in update_existing_head_ref()
685 				existing->extent_op->update_key = true;  in update_existing_head_ref()
688 				existing->extent_op->flags_to_set |=  in update_existing_head_ref()
690 				existing->extent_op->update_flags = true;  in update_existing_head_ref()
700 	old_ref_mod = existing->total_ref_mod;  in update_existing_head_ref()
701 	existing->ref_mod += update->ref_mod;  in update_existing_head_ref()
702 	existing->total_ref_mod += update->ref_mod;  in update_existing_head_ref()
710 	if (existing->is_data) {  in update_existing_head_ref()
713 						   existing->num_bytes);  in update_existing_head_ref()
715 		if (existing->total_ref_mod >= 0 && old_ref_mod < 0) {  in update_existing_head_ref()
716 			delayed_refs->pending_csums -= existing->num_bytes;  in update_existing_head_ref()
719 		if (existing->total_ref_mod < 0 && old_ref_mod >= 0) {  in update_existing_head_ref()
720 			delayed_refs->pending_csums += existing->num_bytes;  in update_existing_head_ref()
725 	spin_unlock(&existing->lock);  in update_existing_head_ref()
817 	struct btrfs_delayed_ref_head *existing;  in add_delayed_ref_head()  local
857 	existing = xa_load(&delayed_refs->head_refs, index);  in add_delayed_ref_head()
858 	if (existing) {  in add_delayed_ref_head()
859 		update_existing_head_ref(trans, existing, head_ref);  in add_delayed_ref_head()
861 		 * we've updated the existing ref, free the newly  in add_delayed_ref_head()
865 		head_ref = existing;  in add_delayed_ref_head()
867 		existing = xa_store(&delayed_refs->head_refs, index, head_ref, GFP_ATOMIC);  in add_delayed_ref_head()
868 		if (xa_is_err(existing)) {  in add_delayed_ref_head()
870 			ASSERT(xa_err(existing) != -ENOMEM);  in add_delayed_ref_head()
871 			return ERR_PTR(xa_err(existing));  in add_delayed_ref_head()
872 		} else if (WARN_ON(existing)) {  in add_delayed_ref_head()