ATA_QCFLAG_DMAMAP was a bit peculiar in that it got set during qc
initialization and cleared if DMA mapping wasn't necessary. Make it
more straight forward by making the following changes.
* Don't set it during initialization. Set it after DMA is actually
mapped.
* Add BUG_ON() to guarantee that there is data to transfer if DMAMAP
is set. This always holds for the current code. The BUG_ON() is
for docummentation and sanity check.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Tejun Heo
f92a26365a