[ Upstream commit 6c404a68 ]

We need to transfer device ownership to the CPU before we can manipulate
the mapped data.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>