Having granularity set to 1us results in having inode timestamps with a
accurancy different from the fuse client (i.e. atime, ctime and mtime will
always end with '000'). This patch normalizes this behaviour and sets the
granularity to 1.
Signed-off-by: Luis Henriques <lhenriques@suse.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Sage Weil <sage@redhat.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>