Comment 104 for bug 149076

You are not using cdrecord but a defective fork called "wodim".

wodim is a dead fork from a 5 year old version of cdrecord with
bugs added that never have been in the original.

The device or resource busy message is a result from such a bug.

Note that you also do not use mkisofs but "genisoimage" from the
same "fork". Note that "genisoimage" creates defective ISO filesystem
images.

I recommend to use the original software as there are no known bugs
in the original software and as the original software added many new
features during the past 6 years.