[BUG] Regression introduced with "block: split bios to max possible length"

[Stefan Haberland]

Hi,

unfortunately commit e36f62042880 "block: split bios to maxpossible length"
breaks the DASD driver on s390.  We expect the block requests to be multiple
of 4k in size. With the patch applied I see the requests split up in 
multiple
of 512 byte and therefore the requests get rejected and lots of I/Os fail.

Could you please fix or revert the patch?

We have following values set for the block queue:

hw_sector_size         4096
logical_block_size     4096
minimum_io_size        4096
physical_block_size    4096
max_hw_sectors_kb       760
max_sectors_kb          760
max_segment_size       4096
max_segments          65535

Regards,
Stefan