  In the view of the Gliner vacuum, we remove the deformations in the first law
of mechanics for regular black holes, where one part of deformations associated
with black hole mass will be absorbed into enthalpy or internal energy, and the
other part associated with parameters rather than mass will constitute a
natural $V$-$P$ term. The improved first law of mechanics redisplays its
resemblance to the first law of thermodynamic systems, which implies a restored
correspondence of the mechanic variables to the thermodynamic ones. In
particular, the linear relation between the entropy and horizon area remains
unchanged for regular black holes. Based on the modified first law of
thermodynamics, we establish a self-consistent theory of Ruppeiner geometry and
obtain a universal attractive property for the microstructure of regular black
holes. In addition, the repulsive and attractive interactions inside and
outside regular black holes are analyzed in detail.
