SCL_L2ARC
!spa_config_tryenter(spa, SCL_L2ARC, vd, RW_READER))
spa_config_exit(spa, SCL_L2ARC, vd);
spa_config_exit(spa, SCL_L2ARC, vd);
spa_config_enter(next->l2ad_spa, SCL_L2ARC, next, RW_READER);
spa_config_exit(zio->io_spa, SCL_L2ARC, zio->io_vd);
spa_config_exit(spa, SCL_L2ARC, dev);
spa_config_exit(spa, SCL_L2ARC, dev);
spa_config_exit(spa, SCL_L2ARC, dev);
spa_config_enter(spa, SCL_L2ARC, vd, RW_READER);
spa_config_exit(spa, SCL_L2ARC, vd);
if (spa_config_tryenter(spa, SCL_L2ARC, vd,
spa_config_exit(spa, SCL_L2ARC, vd);
spa_config_enter(spa, SCL_L2ARC, FTAG, RW_READER);
spa_config_exit(spa, SCL_L2ARC, FTAG);
#define SCL_STATE_ALL (SCL_STATE | SCL_L2ARC | SCL_ZIO)