Use memcpy_from_bvec instead of open coding the logic.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20220303111905.321089-5-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>