generic_shutdown_super —
common helper for ->kill_sb
void generic_shutdown_super (struct super_block * sb);
generic_shutdown_super does all fs-independent work on superblock
shutdown. Typical ->kill_sb should pick all fs-specific objects
that need destruction out of superblock, call generic_shutdown_super
and release aforementioned objects. Note: dentries and inodes _are_
taken care of and do not need specific handling.