block: raw_async: implement disk resizing

Support for resize events for raw_async disks.

On-behalf-of: SAP thomas.prescher@sap.com
Signed-off-by: Thomas Prescher <thomas.prescher@cyberus-technology.de>

block/src/raw_async.rs

@@ -55,6 +55,10 @@ impl DiskFile for RawFileDisk {
         }
     }
 
+    fn resize(&mut self, size: u64) -> DiskFileResult<()> {
+        self.file.set_len(size).map_err(DiskFileError::ResizeError)
+    }
+
     fn fd(&mut self) -> BorrowedDiskFd<'_> {
         BorrowedDiskFd::new(self.file.as_raw_fd())
     }