[PATCH] s390: don't pad cdl blocks for write requests

The first blocks on a cdl formatted dasd device are smaller than the blocksize
of the device.  Read requests are padded with a 'e5' pattern.  Write requests
should not pad the (user) buffer with 'e5' because a write request is not
allowed to modify the buffer.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>