The read and write versions don't have anything in common except for the
call to iomap_dio_rw.  So split this function, and merge each half into
its only caller.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NGoldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>