mkfs: add optional 'reason' for illegal_option

Allow us to tell the user what exactly is wrong with the specified
options.  For example, that the value is too small, instead of just
generic "bad option."

[dchinner: fix whitespace, simplify illegal option message ]

Signed-off-by: Jan Tulak <jtulak@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 file changed