block: Implement AsyncDiskFile trait for RawFileDiskAio

Add disk_file::AsyncDiskFile trait implementation for
RawFileDiskAio with try_clone() and new_async_io() methods.

try_clone() duplicates the underlying file descriptor and
wraps it in a new RawFileDiskAio. new_async_io() creates a
RawFileAsyncAio (Linux AIO) backend, wrapping errors in
BlockError instead of DiskFileError.

Signed-off-by: Muminul Islam <muislam@microsoft.com>

block/src/raw_async_aio.rs

@@ -117,6 +117,24 @@ impl disk_file::Resizable for RawFileDiskAio {
 
 impl disk_file::DiskFile for RawFileDiskAio {}
 
+impl disk_file::AsyncDiskFile for RawFileDiskAio {
+    fn try_clone(&self) -> BlockResult<Box<dyn disk_file::AsyncDiskFile>> {
+        let file = self
+            .file
+            .try_clone()
+            .map_err(|e| BlockError::new(BlockErrorKind::Io, DiskFileError::Clone(e)))?;
+        Ok(Box::new(RawFileDiskAio { file }))
+    }
+
+    fn new_async_io(&self, ring_depth: u32) -> BlockResult<Box<dyn AsyncIo>> {
+        let mut raw = RawFileAsyncAio::new(self.file.as_raw_fd(), ring_depth)
+            .map_err(|e| BlockError::new(BlockErrorKind::Io, DiskFileError::NewAsyncIo(e)))?;
+        raw.alignment =
+            DiskTopology::probe(&self.file).map_or(SECTOR_SIZE, |t| t.logical_block_size);
+        Ok(Box::new(raw) as Box<dyn AsyncIo>)
+    }
+}
+
 pub struct RawFileAsyncAio {
     fd: RawFd,
     ctx: aio::IoContext,