A flapper type downhole valve is opened by flow against the flapper. The flapper and the housing contain magnets that hold the flapper open after it has been opened by flow to keep the flapper from chattering from the flow going past it. The strength of the force is not sufficient to hold the flapper open against a torsion spring on a pivot pin, when there is no flow through the valve. The valve can still be held in the locked open position with no flow through the housing by pressurizing the surrounding annulus to position another magnet to increase the holding force to a level greater than the force of the torsion spring. The additional magnet is spring biased so that upon removal of annulus pressure it shifts to allow the flapper to close. Alternative designs with and without a flow tube are possible. Fixed or movable restrictions can be associated with the flow tube to create a force to shift it to open a flapper with flow into the well.