block_util, vmm: Add fixed VHD asynchronous implementation

This commit adds the asynchronous support for fixed VHD disk files.

It introduces FixedVhd as a new ImageType, moving the image type
detection to the block_util crate (instead of qcow crate).

It creates a new vhd module in the block_util crate in order to handle
VHD footer, following the VHD specification.

It creates a new fixed_vhd_async module in the block_util crate to
implement the asynchronous version of fixed VHD disk file. It relies on
io_uring.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

block_util/src/fixed_vhd_async.rs

@@ -0,0 +1,110 @@
+// Copyright © 2021 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::async_io::{
+    AsyncIo, AsyncIoError, AsyncIoResult, DiskFile, DiskFileError, DiskFileResult,
+};
+use crate::raw_async::RawFileAsync;
+use crate::vhd::VhdFooter;
+use std::fs::File;
+use std::os::unix::io::{AsRawFd, RawFd};
+use vmm_sys_util::eventfd::EventFd;
+
+pub struct FixedVhdDiskAsync {
+    file: File,
+    size: u64,
+}
+
+impl FixedVhdDiskAsync {
+    pub fn new(mut file: File) -> std::io::Result<Self> {
+        let footer = VhdFooter::new(&mut file)?;
+
+        Ok(FixedVhdDiskAsync {
+            file,
+            size: footer.current_size(),
+        })
+    }
+}
+
+impl DiskFile for FixedVhdDiskAsync {
+    fn size(&mut self) -> DiskFileResult<u64> {
+        Ok(self.size)
+    }
+
+    fn new_async_io(&self, ring_depth: u32) -> DiskFileResult<Box<dyn AsyncIo>> {
+        Ok(Box::new(
+            FixedVhdAsync::new(self.file.as_raw_fd(), ring_depth, self.size)
+                .map_err(DiskFileError::NewAsyncIo)?,
+        ) as Box<dyn AsyncIo>)
+    }
+}
+
+pub struct FixedVhdAsync {
+    raw_file_async: RawFileAsync,
+    size: u64,
+}
+
+impl FixedVhdAsync {
+    pub fn new(fd: RawFd, ring_depth: u32, size: u64) -> std::io::Result<Self> {
+        let raw_file_async = RawFileAsync::new(fd, ring_depth)?;
+
+        Ok(FixedVhdAsync {
+            raw_file_async,
+            size,
+        })
+    }
+}
+
+impl AsyncIo for FixedVhdAsync {
+    fn notifier(&self) -> &EventFd {
+        self.raw_file_async.notifier()
+    }
+
+    fn read_vectored(
+        &mut self,
+        offset: libc::off_t,
+        iovecs: Vec<libc::iovec>,
+        user_data: u64,
+    ) -> AsyncIoResult<()> {
+        if offset as u64 >= self.size {
+            return Err(AsyncIoError::ReadVectored(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                format!(
+                    "Invalid offset {}, can't be larger than file size {}",
+                    offset, self.size
+                ),
+            )));
+        }
+
+        self.raw_file_async.read_vectored(offset, iovecs, user_data)
+    }
+
+    fn write_vectored(
+        &mut self,
+        offset: libc::off_t,
+        iovecs: Vec<libc::iovec>,
+        user_data: u64,
+    ) -> AsyncIoResult<()> {
+        if offset as u64 >= self.size {
+            return Err(AsyncIoError::WriteVectored(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                format!(
+                    "Invalid offset {}, can't be larger than file size {}",
+                    offset, self.size
+                ),
+            )));
+        }
+
+        self.raw_file_async
+            .write_vectored(offset, iovecs, user_data)
+    }
+
+    fn fsync(&mut self, user_data: Option<u64>) -> AsyncIoResult<()> {
+        self.raw_file_async.fsync(user_data)
+    }
+
+    fn complete(&mut self) -> Vec<(u64, i32)> {
+        self.raw_file_async.complete()
+    }
+}