block: Simplify AsyncAdaptor

It shouldn't be necessary to lock the file for the adaptor. This removes
two layers of indirection for QcowDiskSync and VhdxDiskSync.

Signed-off-by: Wei Liu <liuwe@microsoft.com>

block/src/lib.rs

@@ -39,7 +39,7 @@ use std::io::{self, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write};
 use std::os::linux::fs::MetadataExt;
 use std::os::unix::io::AsRawFd;
 use std::path::Path;
-use std::sync::{Arc, MutexGuard};
+use std::sync::Arc;
 use std::time::Instant;
 use std::{cmp, result};
 
@@ -646,10 +646,7 @@ pub fn block_io_uring_is_supported() -> bool {
     }
 }
 
-pub trait AsyncAdaptor<F>
-where
-    F: Read + Write + Seek,
-{
+pub trait AsyncAdaptor {
     fn read_vectored_sync(
         &mut self,
         offset: libc::off_t,
@@ -657,7 +654,10 @@ where
         user_data: u64,
         eventfd: &EventFd,
         completion_list: &mut VecDeque<(u64, i32)>,
-    ) -> AsyncIoResult<()> {
+    ) -> AsyncIoResult<()>
+    where
+        Self: Read + Seek,
+    {
         // Convert libc::iovec into IoSliceMut
         let mut slices: SmallVec<[IoSliceMut; DEFAULT_DESCRIPTOR_VEC_SIZE]> =
             SmallVec::with_capacity(iovecs.len());
@@ -669,15 +669,13 @@ where
         }
 
         let result = {
-            let mut file = self.file();
-
             // Move the cursor to the right offset
-            file.seek(SeekFrom::Start(offset as u64))
+            self.seek(SeekFrom::Start(offset as u64))
                 .map_err(AsyncIoError::ReadVectored)?;
 
             let mut r = 0;
             for b in slices.iter_mut() {
-                r += file.read(b).map_err(AsyncIoError::ReadVectored)?;
+                r += self.read(b).map_err(AsyncIoError::ReadVectored)?;
             }
             r
         };
@@ -695,7 +693,10 @@ where
         user_data: u64,
         eventfd: &EventFd,
         completion_list: &mut VecDeque<(u64, i32)>,
-    ) -> AsyncIoResult<()> {
+    ) -> AsyncIoResult<()>
+    where
+        Self: Write + Seek,
+    {
         // Convert libc::iovec into IoSlice
         let mut slices: SmallVec<[IoSlice; DEFAULT_DESCRIPTOR_VEC_SIZE]> =
             SmallVec::with_capacity(iovecs.len());
@@ -707,15 +708,13 @@ where
         }
 
         let result = {
-            let mut file = self.file();
-
             // Move the cursor to the right offset
-            file.seek(SeekFrom::Start(offset as u64))
+            self.seek(SeekFrom::Start(offset as u64))
                 .map_err(AsyncIoError::WriteVectored)?;
 
             let mut r = 0;
             for b in slices.iter() {
-                r += file.write(b).map_err(AsyncIoError::WriteVectored)?;
+                r += self.write(b).map_err(AsyncIoError::WriteVectored)?;
             }
             r
         };
@@ -731,12 +730,13 @@ where
         user_data: Option<u64>,
         eventfd: &EventFd,
         completion_list: &mut VecDeque<(u64, i32)>,
-    ) -> AsyncIoResult<()> {
+    ) -> AsyncIoResult<()>
+    where
+        Self: Write,
+    {
         let result: i32 = {
-            let mut file = self.file();
-
             // Flush
-            file.flush().map_err(AsyncIoError::Fsync)?;
+            self.flush().map_err(AsyncIoError::Fsync)?;
 
             0
         };
@@ -748,8 +748,6 @@ where
 
         Ok(())
     }
-
-    fn file(&mut self) -> MutexGuard<'_, F>;
 }
 
 pub enum ImageType {

block/src/qcow/mod.rs

@@ -425,7 +425,7 @@ fn max_refcount_clusters(refcount_order: u32, cluster_size: u32, num_clusters: u
 /// #   Ok(())
 /// # }
 /// ```
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct QcowFile {
     raw_file: QcowRawFile,
     header: QcowHeader,

block/src/qcow_sync.rs

@@ -6,7 +6,6 @@ use std::collections::VecDeque;
 use std::fs::File;
 use std::io::{Seek, SeekFrom};
 use std::os::fd::AsRawFd;
-use std::sync::{Arc, Mutex, MutexGuard};
 
 use vmm_sys_util::eventfd::EventFd;
 
@@ -17,22 +16,22 @@ use crate::qcow::{QcowFile, RawFile, Result as QcowResult};
 use crate::AsyncAdaptor;
 
 pub struct QcowDiskSync {
-    qcow_file: Arc<Mutex<QcowFile>>,
+    qcow_file: QcowFile,
 }
 
 impl QcowDiskSync {
     pub fn new(file: File, direct_io: bool) -> QcowResult<Self> {
         Ok(QcowDiskSync {
-            qcow_file: Arc::new(Mutex::new(QcowFile::from(RawFile::new(file, direct_io))?)),
+            qcow_file: QcowFile::from(RawFile::new(file, direct_io))?,
         })
     }
 }
 
 impl DiskFile for QcowDiskSync {
     fn size(&mut self) -> DiskFileResult<u64> {
-        let mut file = self.qcow_file.lock().unwrap();
-
-        file.seek(SeekFrom::End(0)).map_err(DiskFileError::Size)
+        self.qcow_file
+            .seek(SeekFrom::End(0))
+            .map_err(DiskFileError::Size)
     }
 
     fn new_async_io(&self, _ring_depth: u32) -> DiskFileResult<Box<dyn AsyncIo>> {
@@ -40,19 +39,18 @@ impl DiskFile for QcowDiskSync {
     }
 
     fn fd(&mut self) -> BorrowedDiskFd<'_> {
-        let lock = self.qcow_file.lock().unwrap();
-        BorrowedDiskFd::new(lock.as_raw_fd())
+        BorrowedDiskFd::new(self.qcow_file.as_raw_fd())
     }
 }
 
 pub struct QcowSync {
-    qcow_file: Arc<Mutex<QcowFile>>,
+    qcow_file: QcowFile,
     eventfd: EventFd,
     completion_list: VecDeque<(u64, i32)>,
 }
 
 impl QcowSync {
-    pub fn new(qcow_file: Arc<Mutex<QcowFile>>) -> Self {
+    pub fn new(qcow_file: QcowFile) -> Self {
         QcowSync {
             qcow_file,
             eventfd: EventFd::new(libc::EFD_NONBLOCK)
@@ -62,11 +60,7 @@ impl QcowSync {
     }
 }
 
-impl AsyncAdaptor<QcowFile> for Arc<Mutex<QcowFile>> {
-    fn file(&mut self) -> MutexGuard<'_, QcowFile> {
-        self.lock().unwrap()
-    }
-}
+impl AsyncAdaptor for QcowFile {}
 
 impl AsyncIo for QcowSync {
     fn notifier(&self) -> &EventFd {

block/src/vhdx_sync.rs

@@ -5,7 +5,6 @@
 use std::collections::VecDeque;
 use std::fs::File;
 use std::os::fd::AsRawFd;
-use std::sync::{Arc, Mutex, MutexGuard};
 
 use vmm_sys_util::eventfd::EventFd;
 
@@ -16,20 +15,20 @@ use crate::vhdx::{Result as VhdxResult, Vhdx};
 use crate::AsyncAdaptor;
 
 pub struct VhdxDiskSync {
-    vhdx_file: Arc<Mutex<Vhdx>>,
+    vhdx_file: Vhdx,
 }
 
 impl VhdxDiskSync {
     pub fn new(f: File) -> VhdxResult<Self> {
         Ok(VhdxDiskSync {
-            vhdx_file: Arc::new(Mutex::new(Vhdx::new(f)?)),
+            vhdx_file: Vhdx::new(f)?,
         })
     }
 }
 
 impl DiskFile for VhdxDiskSync {
     fn size(&mut self) -> DiskFileResult<u64> {
-        Ok(self.vhdx_file.lock().unwrap().virtual_disk_size())
+        Ok(self.vhdx_file.virtual_disk_size())
     }
 
     fn new_async_io(&self, _ring_depth: u32) -> DiskFileResult<Box<dyn AsyncIo>> {
@@ -40,19 +39,18 @@ impl DiskFile for VhdxDiskSync {
     }
 
     fn fd(&mut self) -> BorrowedDiskFd<'_> {
-        let lock = self.vhdx_file.lock().unwrap();
-        BorrowedDiskFd::new(lock.as_raw_fd())
+        BorrowedDiskFd::new(self.vhdx_file.as_raw_fd())
     }
 }
 
 pub struct VhdxSync {
-    vhdx_file: Arc<Mutex<Vhdx>>,
+    vhdx_file: Vhdx,
     eventfd: EventFd,
     completion_list: VecDeque<(u64, i32)>,
 }
 
 impl VhdxSync {
-    pub fn new(vhdx_file: Arc<Mutex<Vhdx>>) -> std::io::Result<Self> {
+    pub fn new(vhdx_file: Vhdx) -> std::io::Result<Self> {
         Ok(VhdxSync {
             vhdx_file,
             eventfd: EventFd::new(libc::EFD_NONBLOCK)?,
@@ -61,11 +59,7 @@ impl VhdxSync {
     }
 }
 
-impl AsyncAdaptor<Vhdx> for Arc<Mutex<Vhdx>> {
-    fn file(&mut self) -> MutexGuard<'_, Vhdx> {
-        self.lock().unwrap()
-    }
-}
+impl AsyncAdaptor for Vhdx {}
 
 impl AsyncIo for VhdxSync {
     fn notifier(&self) -> &EventFd {