BTRFS_ROOT_IN_RADIX
set_bit(BTRFS_ROOT_IN_RADIX, &root->state);
if (test_bit(BTRFS_ROOT_IN_RADIX, &gang[0]->state))
if (test_and_clear_bit(BTRFS_ROOT_IN_RADIX, &root->state))
if (test_bit(BTRFS_ROOT_IN_RADIX, &root->state))
if (WARN_ON(test_bit(BTRFS_ROOT_IN_RADIX, &root->state)))