\[ y(x) \left (a^2+\frac {a f'(x)}{f(x)}-b^2 f(x)^2\right )-y'(x) \left (2 a+\frac {f'(x)}{f(x)}\right )+y''(x)=0 \] ✗ Mathematica : cpu = 0.313091 (sec), leaf count = 0 , could not solve
DSolve[y[x]*(a^2 - b^2*f[x]^2 + (a*Derivative[1][f][x])/f[x]) - (2*a + Derivative[1][f][x]/f[x])*Derivative[1][y][x] + Derivative[2][y][x] == 0, y[x], x]
✓ Maple : cpu = 0.433 (sec), leaf count = 74
\[ \left \{ y \left ( x \right ) ={{\rm e}^{\int \!-{1 \left ( {\frac {f \left ( x \right ) \left ( {{\rm e}^{{\it \_C1}\,b}} \right ) ^{2}b}{ \left ( {{\rm e}^{b\int \!f \left ( x \right ) \,{\rm d}x}} \right ) ^{2}}}+bf \left ( x \right ) -{\frac { \left ( {{\rm e}^{{\it \_C1}\,b}} \right ) ^{2}a}{ \left ( {{\rm e}^{b\int \!f \left ( x \right ) \,{\rm d}x}} \right ) ^{2}}}+a \right ) \left ( {\frac { \left ( {{\rm e}^{{\it \_C1}\,b}} \right ) ^{2}}{ \left ( {{\rm e}^{b\int \!f \left ( x \right ) \,{\rm d}x}} \right ) ^{2}}}-1 \right ) ^{-1}}\,{\rm d}x}}{\it \_C2} \right \} \]