BTLALIGN
BTLALIGN(sizeof(uint32_t) + sizeof(pgno_t) + sizeof(uint8_t) + (len))
BTLALIGN(sizeof(recno_t) + sizeof(pgno_t))
BTLALIGN(sizeof(uint32_t) + sizeof(uint32_t) + sizeof(uint8_t) + \
BTLALIGN(sizeof(uint32_t) + sizeof(uint8_t) + (dsize))