Remove the insane infrastructure for preallocating coheren DMA regions,
and just allocate the memory where needed. This also gets rid of the
aligment adjustments given that Documentation/DMA-API-HOWTO.txt sais:
"The cpu return address and the DMA bus master address are both
guaranteed to be aligned to the smallest PAGE_SIZE order which
is greater than or equal to the requested size. This invariant
exists (for example) to guarantee that if you allocate a chunk
which is smaller than or equal to 64 kilobytes, the extent of the
buffer you receive will not cross a 64K boundary."
Signed-off-by: Christoph Hellwig <hch@lst.de>
[djbw: moved allocation from start to init, re-add memset]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
bc5c96748a