ZIL_PREV_BLKS
uint_t zl_prev_blks[ZIL_PREV_BLKS]; /* size - sector rounded */
for (i = 0; i < ZIL_PREV_BLKS; i++)
zilog->zl_prev_rotor = (zilog->zl_prev_rotor + 1) & (ZIL_PREV_BLKS - 1);