Bug#900442: other source of error

[David Garfield]

I've had the same error happen ("generic_make_request: Trying to write
to read-only block-device "...) when running os-prober through grub on
my basically "wheezy" system.  I removed os-prober, to stop having to do
a 12 hour resync of the raid5 array every time I updated the kernel.