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block, virtio-devices: Use owned async I/O requests

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Switch virtio-blk request construction and the users to the owned
AsyncIo data path added in the series. Read bounce buffers now return
through AsyncIoCompletion before being copied back to guest memory.

This makes the main virtio async block I/O path use retained request
memory. qcow still has raw-iovec fallback paths at this point; those
are removed in follow-up commits.

Leave the legacy borrowed iovec trait methods in place for a follow-up
cleanup commit to minimize single-commit churn.

Signed-off-by: Dylan Reid <dgreid@fb.com>
This commit is contained in:
Dylan Reid
2026-05-22 14:41:37 -07:00
committed by Rob Bradford
parent 1dfc642e9a
commit 2da8507d21
4 changed files with 112 additions and 130 deletions
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virtio-devices/src/block.rs
+28 -31
View File
@@ -6,6 +6,8 @@
//
// Copyright © 2020 Intel Corporation
//
// Copyright (c) Meta Platforms, Inc. and affiliates.
//
// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
use std::cmp::max;
@@ -303,7 +305,7 @@ impl BlockEpollHandler {
request.writeback = self.writeback.load(Ordering::Acquire);
let result = request.execute_async(
desc_chain.memory(),
self.mem.memory().into_inner(),
self.disk_nsectors.load(Ordering::SeqCst),
self.disk_image.as_mut(),
&self.serial,
@@ -317,15 +319,7 @@ impl BlockEpollHandler {
}) = result
{
if let Some(batch_request) = batch_request {
match batch_request.request_type {
RequestType::In | RequestType::Out => batch_requests.push(batch_request),
_ => {
unreachable!(
"Unexpected batch request type: {:?}",
request.request_type()
)
}
}
batch_requests.push(batch_request);
batch_inflight_requests.push((desc_chain.head_index(), request));
} else {
self.inflight_requests
@@ -363,24 +357,26 @@ impl BlockEpollHandler {
}
}
match self.disk_image.submit_batch_requests(&batch_requests) {
Ok(()) => {
self.inflight_requests.extend(batch_inflight_requests);
}
Err(e) => {
// If batch submission fails, report VIRTIO_BLK_S_IOERR for all requests.
for (user_data, request) in batch_inflight_requests {
warn!("Request failed with batch submission: {request:x?} {e:?}");
let desc_index = user_data;
let mem = self.mem.memory();
mem.write_obj(VIRTIO_BLK_S_IOERR as u8, request.status_addr())
.map_err(Error::RequestStatus)?;
queue
.add_used(mem.deref(), desc_index, 1)
.map_err(Error::QueueAddUsed)?;
queue
.enable_notification(mem.deref())
.map_err(Error::QueueEnableNotification)?;
if !batch_requests.is_empty() {
match self.disk_image.submit_batch_operations(batch_requests) {
Ok(()) => {
self.inflight_requests.extend(batch_inflight_requests);
}
Err(e) => {
// If batch submission fails, report VIRTIO_BLK_S_IOERR for all requests.
for (user_data, request) in batch_inflight_requests {
warn!("Request failed with batch submission: {request:x?} {e:?}");
let desc_index = user_data;
let mem = self.mem.memory();
mem.write_obj(VIRTIO_BLK_S_IOERR as u8, request.status_addr())
.map_err(Error::RequestStatus)?;
queue
.add_used(mem.deref(), desc_index, 1)
.map_err(Error::QueueAddUsed)?;
queue
.enable_notification(mem.deref())
.map_err(Error::QueueEnableNotification)?;
}
}
}
}
@@ -451,13 +447,14 @@ impl BlockEpollHandler {
let mut read_ops = Wrapping(0);
let mut write_ops = Wrapping(0);
while let Some((user_data, result)) = self.disk_image.next_completed_request() {
let desc_index = user_data as u16;
while let Some(mut completion) = self.disk_image.next_completion() {
let result = completion.result;
let desc_index = completion.user_data as u16;
let mut request = self.find_inflight_request(desc_index)?;
request
.complete_async(&mem)
.complete_async(&mem, &mut completion)
.map_err(Error::RequestCompleting)?;
let latency = request.start().elapsed().as_micros() as u64;