Here is an updated patch for the floppy driver which got broken in
2.5.13. "read block 0 on ->revalidate()" is now implemented through
the bio interface, following a suggestion by Christoph Hellwig.

I still cannot explain why block_dev.c's ->bd_block_size change
caused data corruption, but removing that code fixes the floppy
driver and doesn't seem to cause any problems on my test box.