vhost-user-backend: Don't create MmapRegion separately

GuestRegionMmap::from_range() can take care of creating the region as
well now, use it.

Signed-off-by: Viresh Kumar <[email protected]>

Author: vireshk

crates/vhost-user-backend/src/handler.rs

@@ -22,9 +22,7 @@ use virtio_bindings::bindings::virtio_ring::VIRTIO_RING_F_EVENT_IDX;
 use virtio_queue::{Error as VirtQueError, QueueT};
 use vm_memory::bitmap::Bitmap;
 use vm_memory::mmap::NewBitmap;
-use vm_memory::{
-    FileOffset, GuestAddress, GuestAddressSpace, GuestMemoryMmap, GuestRegionMmap, MmapRegion,
-};
+use vm_memory::{FileOffset, GuestAddress, GuestAddressSpace, GuestMemoryMmap, GuestRegionMmap};
 use vmm_sys_util::epoll::EventSet;
 
 use super::backend::VhostUserBackend;
@@ -527,15 +525,15 @@ where
         region: &VhostUserSingleMemoryRegion,
         file: File,
     ) -> VhostUserResult<()> {
-        let mmap_region = MmapRegion::from_file(
-            FileOffset::new(file, region.mmap_offset),
-            region.memory_size as usize,
-        )
-        .map_err(|e| VhostUserError::ReqHandlerError(io::Error::new(io::ErrorKind::Other, e)))?;
         let guest_region = Arc::new(
-            GuestRegionMmap::new(mmap_region, GuestAddress(region.guest_phys_addr)).map_err(
-                |e| VhostUserError::ReqHandlerError(io::Error::new(io::ErrorKind::Other, e)),
-            )?,
+            GuestRegionMmap::from_range(
+                GuestAddress(region.guest_phys_addr),
+                region.memory_size as usize,
+                Some(FileOffset::new(file, region.mmap_offset)),
+            )
+            .map_err(|e| {
+                VhostUserError::ReqHandlerError(io::Error::new(io::ErrorKind::Other, e))
+            })?,
         );
 
         let mem = self