There's a single underlying bo mapping shared by the initial alloc here
and the later import of the same. The mapping size has to be initialized
with the real size of the created blob resource, since the app can query
the exported native handle size for re-import. e.g. lseek dma-buf size
Similar to virtgpu_bo_create_from_device_memory, the app can do multiple
imports with different sizes for suballocation. So on the initial
import, the mapping size has to be initialized with the real size of the
backing blob resource.
Backport-to: 25.3
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38443>
Yiwei Zhang
0afc408cb9