commit 8de58074 upstream.

We may exit this function without properly freeing up the maapings
we may have acquired. Fix the bug.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
Signed-off-by: Zefan Li <lizefan@huawei.com>