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https://github.com/cloud-hypervisor/cloud-hypervisor.git
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12e20effd7
Based on the synchronous QCOW file implementation present in the qcow crate, we created a new qcow_sync module in block_util that ports this synchronous implementation to the AsyncIo trait. The point is to reuse virtio-blk asynchronous implementation for both synchronous and asynchronous backends. Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
165 lines
4.6 KiB
Rust
165 lines
4.6 KiB
Rust
// Copyright © 2021 Intel Corporation
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//
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// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
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use crate::async_io::{
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AsyncIo, AsyncIoError, AsyncIoResult, DiskFile, DiskFileError, DiskFileResult,
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};
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use qcow::{QcowFile, RawFile};
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use std::fs::File;
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use std::io::{IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write};
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use std::sync::{Arc, Mutex};
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use vmm_sys_util::eventfd::EventFd;
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pub struct QcowDiskSync {
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qcow_file: QcowFile,
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semaphore: Arc<Mutex<()>>,
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}
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impl QcowDiskSync {
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pub fn new(file: File, direct_io: bool) -> Self {
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QcowDiskSync {
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qcow_file: QcowFile::from(RawFile::new(file, direct_io))
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.expect("Failed creating QcowFile"),
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semaphore: Arc::new(Mutex::new(())),
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}
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}
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}
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impl DiskFile for QcowDiskSync {
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fn size(&mut self) -> DiskFileResult<u64> {
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// Take the semaphore to ensure other threads are not interacting with
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// the underlying file.
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let _lock = self.semaphore.lock().unwrap();
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Ok(self
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.qcow_file
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.seek(SeekFrom::End(0))
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.map_err(DiskFileError::Size)? as u64)
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}
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fn new_async_io(&self, _ring_depth: u32) -> DiskFileResult<Box<dyn AsyncIo>> {
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Ok(Box::new(QcowSync::new(
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self.qcow_file.clone(),
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self.semaphore.clone(),
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)) as Box<dyn AsyncIo>)
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}
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}
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pub struct QcowSync {
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qcow_file: QcowFile,
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eventfd: EventFd,
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completion_list: Vec<(u64, i32)>,
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semaphore: Arc<Mutex<()>>,
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}
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impl QcowSync {
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pub fn new(qcow_file: QcowFile, semaphore: Arc<Mutex<()>>) -> Self {
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QcowSync {
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qcow_file,
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eventfd: EventFd::new(libc::EFD_NONBLOCK)
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.expect("Failed creating EventFd for QcowSync"),
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completion_list: Vec::new(),
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semaphore,
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}
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}
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}
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impl AsyncIo for QcowSync {
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fn notifier(&self) -> &EventFd {
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&self.eventfd
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}
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fn read_vectored(
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&mut self,
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offset: libc::off_t,
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iovecs: Vec<libc::iovec>,
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user_data: u64,
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) -> AsyncIoResult<()> {
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// Convert libc::iovec into IoSliceMut
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let mut slices = Vec::new();
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for iovec in iovecs.iter() {
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slices.push(IoSliceMut::new(unsafe { std::mem::transmute(*iovec) }));
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}
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let result = {
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// Take the semaphore to ensure other threads are not interacting
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// with the underlying file.
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let _lock = self.semaphore.lock().unwrap();
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// Move the cursor to the right offset
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self.qcow_file
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.seek(SeekFrom::Start(offset as u64))
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.map_err(AsyncIoError::ReadVectored)?;
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// Read vectored
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self.qcow_file
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.read_vectored(slices.as_mut_slice())
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.map_err(AsyncIoError::ReadVectored)?
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};
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self.completion_list.push((user_data, result as i32));
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self.eventfd.write(1).unwrap();
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Ok(())
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}
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fn write_vectored(
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&mut self,
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offset: libc::off_t,
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iovecs: Vec<libc::iovec>,
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user_data: u64,
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) -> AsyncIoResult<()> {
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// Convert libc::iovec into IoSlice
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let mut slices = Vec::new();
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for iovec in iovecs.iter() {
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slices.push(IoSlice::new(unsafe { std::mem::transmute(*iovec) }));
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}
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let result = {
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// Take the semaphore to ensure other threads are not interacting
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// with the underlying file.
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let _lock = self.semaphore.lock().unwrap();
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// Move the cursor to the right offset
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self.qcow_file
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.seek(SeekFrom::Start(offset as u64))
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.map_err(AsyncIoError::WriteVectored)?;
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// Write vectored
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self.qcow_file
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.write_vectored(slices.as_slice())
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.map_err(AsyncIoError::WriteVectored)?
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};
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self.completion_list.push((user_data, result as i32));
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self.eventfd.write(1).unwrap();
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Ok(())
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}
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fn fsync(&mut self, user_data: Option<u64>) -> AsyncIoResult<()> {
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let result: i32 = {
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// Take the semaphore to ensure other threads are not interacting
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// with the underlying file.
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let _lock = self.semaphore.lock().unwrap();
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// Flush
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self.qcow_file.flush().map_err(AsyncIoError::Fsync)?;
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0
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};
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if let Some(user_data) = user_data {
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self.completion_list.push((user_data, result));
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self.eventfd.write(1).unwrap();
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}
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Ok(())
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}
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fn complete(&mut self) -> Vec<(u64, i32)> {
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self.completion_list.drain(..).collect()
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}
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}
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