block_util, vhdx: vhdx crate integration with the cloud hypervisor

vhdx_sync.rs in block_util implements traits to represent the vhdx
crate as a supported block device in the cloud hypervisor. The vhdx
is added to the block device list in device_manager.rs at the vmm
crate so that it can automatically detect a vhdx disk and invoke the
corresponding crate.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Fazla Mehrab <akm.fazla.mehrab@intel.com>

block_util/src/vhdx_sync.rs

@@ -0,0 +1,113 @@
+// Copyright © 2021 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+
+use crate::async_io::{AsyncIo, AsyncIoResult, DiskFile, DiskFileError, DiskFileResult};
+use crate::{fsync_sync, read_vectored_sync, write_vectored_sync};
+use std::fs::File;
+use std::ops::DerefMut;
+use std::sync::{Arc, Mutex};
+use vhdx::vhdx::{Result as VhdxResult, Vhdx};
+use vmm_sys_util::eventfd::EventFd;
+
+pub struct VhdxDiskSync {
+    vhdx_file: Arc<Mutex<Vhdx>>,
+    semaphore: Arc<Mutex<()>>,
+}
+
+impl VhdxDiskSync {
+    pub fn new(f: File) -> VhdxResult<Self> {
+        let vhdx = Vhdx::new(f)?;
+        let vhdx_file = Arc::new(Mutex::new(vhdx));
+
+        Ok(VhdxDiskSync {
+            vhdx_file,
+            semaphore: Arc::new(Mutex::new(())),
+        })
+    }
+}
+
+impl DiskFile for VhdxDiskSync {
+    fn size(&mut self) -> DiskFileResult<u64> {
+        Ok(self.vhdx_file.lock().unwrap().virtual_disk_size())
+    }
+
+    fn new_async_io(&self, _ring_depth: u32) -> DiskFileResult<Box<dyn AsyncIo>> {
+        Ok(Box::new(
+            VhdxSync::new(self.vhdx_file.clone(), self.semaphore.clone())
+                .map_err(DiskFileError::NewAsyncIo)?,
+        ) as Box<dyn AsyncIo>)
+    }
+}
+
+pub struct VhdxSync {
+    vhdx_file: Arc<Mutex<Vhdx>>,
+    eventfd: EventFd,
+    completion_list: Vec<(u64, i32)>,
+    semaphore: Arc<Mutex<()>>,
+}
+
+impl VhdxSync {
+    pub fn new(vhdx_file: Arc<Mutex<Vhdx>>, semaphore: Arc<Mutex<()>>) -> std::io::Result<Self> {
+        Ok(VhdxSync {
+            vhdx_file,
+            eventfd: EventFd::new(libc::EFD_NONBLOCK)?,
+            completion_list: Vec::new(),
+            semaphore,
+        })
+    }
+}
+
+impl AsyncIo for VhdxSync {
+    fn notifier(&self) -> &EventFd {
+        &self.eventfd
+    }
+
+    fn read_vectored(
+        &mut self,
+        offset: libc::off_t,
+        iovecs: Vec<libc::iovec>,
+        user_data: u64,
+    ) -> AsyncIoResult<()> {
+        read_vectored_sync(
+            offset,
+            iovecs,
+            user_data,
+            self.vhdx_file.lock().unwrap().deref_mut(),
+            &self.eventfd,
+            &mut self.completion_list,
+            &mut self.semaphore,
+        )
+    }
+
+    fn write_vectored(
+        &mut self,
+        offset: libc::off_t,
+        iovecs: Vec<libc::iovec>,
+        user_data: u64,
+    ) -> AsyncIoResult<()> {
+        write_vectored_sync(
+            offset,
+            iovecs,
+            user_data,
+            self.vhdx_file.lock().unwrap().deref_mut(),
+            &self.eventfd,
+            &mut self.completion_list,
+            &mut self.semaphore,
+        )
+    }
+
+    fn fsync(&mut self, user_data: Option<u64>) -> AsyncIoResult<()> {
+        fsync_sync(
+            user_data,
+            self.vhdx_file.lock().unwrap().deref_mut(),
+            &self.eventfd,
+            &mut self.completion_list,
+            &mut self.semaphore,
+        )
+    }
+
+    fn complete(&mut self) -> Vec<(u64, i32)> {
+        self.completion_list.drain(..).collect()
+    }
+}