Solving the sparse matrix linear equation Ax=b

Solving the sparse matrix linear equation Ax=b. Fortran+cuda C
Ax=b1,Ax=b2,Ax=b3,…,Ax=bn
In Fortran program , I can get ‘A’ , and then put it into cuda C program to get the Factors of A.
But now ,‘A’ is the same,‘b’ is different.I need to save this Factors in GPU first ,and then second to get the answer x with different ‘b’ . The factorization of A and Solve with different ‘b’ need to be in different ‘.cu’ files.
How should this be achieved ?