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crosvm/io_uring/src/uring.rs
Noah Gold b3fca20e24 Refactor cros_async interface to avoid RawFd. 
Instead of creating IoSourceExt from AsRawFd implementers, we've
switched to creating from a marker trait `IntoAsync`. This lets us use
other types like RawDescriptor easily with this crate.  By using the
marker, we also provide some type safety by requiring consumers of
IoSourceExt to declare that their type is expected to work with async
operations. This way we can provide stronger guarantees that an async
IO trait object will behave in a reasonable way.

This CL also purges the cros_async -> base and io_uring -> base
references, and provides the base types needed to add new async
primitives to base.

BUG=none
TEST=builds

Change-Id: I0b0ce6ca7938b22ae8e8fb4e604439f0292678f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2504481
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Noah Gold <nkgold@google.com>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>
2020-11-10 11:40:50 +00:00

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// Copyright 2020 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This file makes several casts from u8 pointers into more-aligned pointer types.
// We assume that the kernel will give us suitably aligned memory.
#![allow(clippy::cast_ptr_alignment)]
use std::collections::BTreeMap;
use std::fmt;
use std::fs::File;
use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
use std::pin::Pin;
use std::ptr::null_mut;
use std::sync::atomic::{AtomicU32, Ordering};
use sys_util::{MappedRegion, MemoryMapping, Protection, WatchingEvents};
use crate::bindings::*;
use crate::syscalls::*;
/// Holds per-operation, user specified data. The usage is up to the caller. The most common use is
/// for callers to identify each request.
pub type UserData = u64;
#[derive(Debug)]
pub enum Error {
/// The call to `io_uring_enter` failed with the given errno.
RingEnter(libc::c_int),
/// The call to `io_uring_setup` failed with the given errno.
Setup(libc::c_int),
/// Failed to map the completion ring.
MappingCompleteRing(sys_util::MmapError),
/// Failed to map the submit ring.
MappingSubmitRing(sys_util::MmapError),
/// Failed to map submit entries.
MappingSubmitEntries(sys_util::MmapError),
/// Too many ops are already queued.
NoSpace,
}
pub type Result<T> = std::result::Result<T, Error>;
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::Error::*;
match self {
RingEnter(e) => write!(f, "Failed to enter io uring {}", e),
Setup(e) => write!(f, "Failed to setup io uring {}", e),
MappingCompleteRing(e) => write!(f, "Failed to mmap completion ring {}", e),
MappingSubmitRing(e) => write!(f, "Failed to mmap submit ring {}", e),
MappingSubmitEntries(e) => write!(f, "Failed to mmap submit entries {}", e),
NoSpace => write!(
f,
"No space for more ring entries, try increasing the size passed to `new`",
),
}
}
}
/// Basic statistics about the operations that have been submitted to the uring.
#[derive(Default)]
pub struct URingStats {
total_enter_calls: u64, // Number of times the uring has been entered.
total_ops: u64, // Total ops submitted to io_uring.
total_complete: u64, // Total ops completed by io_uring.
}
/// Unsafe wrapper for the kernel's io_uring interface. Allows for queueing multiple I/O operations
/// to the kernel and asynchronously handling the completion of these operations.
/// Use the various `add_*` functions to configure operations, then call `wait` to start
/// the operations and get any completed results. Each op is given a u64 user_data argument that is
/// used to identify the result when returned in the iterator provided by `wait`.
///
/// # Example polling an FD for readable status.
///
/// ```
/// # use std::fs::File;
/// # use std::os::unix::io::AsRawFd;
/// # use std::path::Path;
/// # use sys_util::WatchingEvents;
/// # use io_uring::URingContext;
/// let f = File::open(Path::new("/dev/zero")).unwrap();
/// let mut uring = URingContext::new(16).unwrap();
/// uring
/// .add_poll_fd(f.as_raw_fd(), &WatchingEvents::empty().set_read(), 454)
/// .unwrap();
/// let (user_data, res) = uring.wait().unwrap().next().unwrap();
/// assert_eq!(user_data, 454 as io_uring::UserData);
/// assert_eq!(res.unwrap(), 1 as u32);
///
/// ```
pub struct URingContext {
ring_file: File, // Holds the io_uring context FD returned from io_uring_setup.
submit_ring: SubmitQueueState,
submit_queue_entries: SubmitQueueEntries,
complete_ring: CompleteQueueState,
io_vecs: Pin<Box<[libc::iovec]>>,
in_flight: usize, // The number of pending operations.
added: usize, // The number of ops added since the last call to `io_uring_enter`.
num_sqes: usize, // The total number of sqes allocated in shared memory.
stats: URingStats,
}
impl URingContext {
/// Creates a `URingContext` where the underlying uring has a space for `num_entries`
/// simultaneous operations.
pub fn new(num_entries: usize) -> Result<URingContext> {
let ring_params = io_uring_params::default();
// The below unsafe block isolates the creation of the URingContext. Each step on it's own
// is unsafe. Using the uring FD for the mapping and the offsets returned by the kernel for
// base addresses maintains safety guarantees assuming the kernel API guarantees are
// trusted.
unsafe {
// Safe because the kernel is trusted to only modify params and `File` is created with
// an FD that it takes complete ownership of.
let fd = io_uring_setup(num_entries, &ring_params).map_err(Error::Setup)?;
let ring_file = File::from_raw_fd(fd);
// Mmap the submit and completion queues.
// Safe because we trust the kernel to set valid sizes in `io_uring_setup` and any error
// is checked.
let submit_ring = SubmitQueueState::new(
MemoryMapping::from_fd_offset_protection_populate(
&ring_file,
ring_params.sq_off.array as usize
+ ring_params.sq_entries as usize * std::mem::size_of::<u32>(),
u64::from(IORING_OFF_SQ_RING),
Protection::read_write(),
true,
)
.map_err(Error::MappingSubmitRing)?,
&ring_params,
);
let num_sqe = ring_params.sq_entries as usize;
let submit_queue_entries = SubmitQueueEntries {
mmap: MemoryMapping::from_fd_offset_protection_populate(
&ring_file,
ring_params.sq_entries as usize * std::mem::size_of::<io_uring_sqe>(),
u64::from(IORING_OFF_SQES),
Protection::read_write(),
true,
)
.map_err(Error::MappingSubmitEntries)?,
len: num_sqe,
};
let complete_ring = CompleteQueueState::new(
MemoryMapping::from_fd_offset_protection_populate(
&ring_file,
ring_params.cq_off.cqes as usize
+ ring_params.cq_entries as usize * std::mem::size_of::<io_uring_cqe>(),
u64::from(IORING_OFF_CQ_RING),
Protection::read_write(),
true,
)
.map_err(Error::MappingCompleteRing)?,
&ring_params,
);
Ok(URingContext {
ring_file,
submit_ring,
submit_queue_entries,
complete_ring,
io_vecs: Pin::from(
vec![
libc::iovec {
iov_base: null_mut(),
iov_len: 0
};
num_sqe
]
.into_boxed_slice(),
),
added: 0,
num_sqes: ring_params.sq_entries as usize,
in_flight: 0,
stats: Default::default(),
})
}
}
// Call `f` with the next available sqe or return an error if none are available.
// After `f` returns, the sqe is appended to the kernel's queue.
fn prep_next_sqe<F>(&mut self, mut f: F) -> Result<()>
where
F: FnMut(&mut io_uring_sqe, &mut libc::iovec),
{
if self.added == self.num_sqes {
return Err(Error::NoSpace);
}
// Find the next free submission entry in the submit ring and fill it with an iovec.
// The below raw pointer derefs are safe because the memory the pointers use lives as long
// as the mmap in self.
let tail = self.submit_ring.pointers.tail(Ordering::Relaxed);
let next_tail = tail.wrapping_add(1);
if next_tail == self.submit_ring.pointers.head(Ordering::Acquire) {
return Err(Error::NoSpace);
}
// `tail` is the next sqe to use.
let index = (tail & self.submit_ring.ring_mask) as usize;
let sqe = self.submit_queue_entries.get_mut(index).unwrap();
f(sqe, &mut self.io_vecs[index]);
// Tells the kernel to use the new index when processing the entry at that index.
self.submit_ring.set_array_entry(index, index as u32);
// Ensure the above writes to sqe are seen before the tail is updated.
// set_tail uses Release ordering when storing to the ring.
self.submit_ring.pointers.set_tail(next_tail);
self.added += 1;
Ok(())
}
unsafe fn add_rw_op(
&mut self,
ptr: *const u8,
len: usize,
fd: RawFd,
offset: u64,
user_data: UserData,
op: u8,
) -> Result<()> {
self.prep_next_sqe(|sqe, iovec| {
iovec.iov_base = ptr as *const libc::c_void as *mut _;
iovec.iov_len = len;
sqe.opcode = op;
sqe.addr = iovec as *const _ as *const libc::c_void as u64;
sqe.len = 1;
sqe.__bindgen_anon_1.off = offset;
sqe.__bindgen_anon_3.__bindgen_anon_1.buf_index = 0;
sqe.ioprio = 0;
sqe.user_data = user_data;
sqe.flags = 0;
sqe.fd = fd;
})?;
Ok(())
}
/// Asynchronously writes to `fd` from the address given in `ptr`.
/// # Safety
/// `add_write` will write up to `len` bytes of data from the address given by `ptr`. This is
/// only safe if the caller guarantees that the memory lives until the transaction is complete
/// and that completion has been returned from the `wait` function. In addition there must not
/// be other references to the data pointed to by `ptr` until the operation completes. Ensure
/// that the fd remains open until the op completes as well.
pub unsafe fn add_write(
&mut self,
ptr: *const u8,
len: usize,
fd: RawFd,
offset: u64,
user_data: UserData,
) -> Result<()> {
self.add_rw_op(ptr, len, fd, offset, user_data, IORING_OP_WRITEV as u8)
}
/// Asynchronously reads from `fd` to the address given in `ptr`.
/// # Safety
/// `add_read` will write up to `len` bytes of data to the address given by `ptr`. This is only
/// safe if the caller guarantees there are no other references to that memory and that the
/// memory lives until the transaction is complete and that completion has been returned from
/// the `wait` function. In addition there must not be any mutable references to the data
/// pointed to by `ptr` until the operation completes. Ensure that the fd remains open until
/// the op completes as well.
pub unsafe fn add_read(
&mut self,
ptr: *mut u8,
len: usize,
fd: RawFd,
offset: u64,
user_data: UserData,
) -> Result<()> {
self.add_rw_op(ptr, len, fd, offset, user_data, IORING_OP_READV as u8)
}
/// See 'writev' but accepts an iterator instead of a vector if there isn't already a vector in
/// existence.
pub unsafe fn add_writev_iter<I>(
&mut self,
iovecs: I,
fd: RawFd,
offset: u64,
user_data: UserData,
) -> Result<()>
where
I: Iterator<Item = libc::iovec>,
{
self.add_writev(
Pin::from(iovecs.collect::<Vec<_>>().into_boxed_slice()),
fd,
offset,
user_data,
)
}
/// Asynchronously writes to `fd` from the addresses given in `iovecs`.
/// # Safety
/// `add_writev` will write to the address given by `iovecs`. This is only safe if the caller
/// guarantees there are no other references to that memory and that the memory lives until the
/// transaction is complete and that completion has been returned from the `wait` function. In
/// addition there must not be any mutable references to the data pointed to by `iovecs` until
/// the operation completes. Ensure that the fd remains open until the op completes as well.
/// The iovecs reference must be kept alive until the op returns.
pub unsafe fn add_writev(
&mut self,
iovecs: Pin<Box<[libc::iovec]>>,
fd: RawFd,
offset: u64,
user_data: UserData,
) -> Result<()> {
self.prep_next_sqe(|sqe, _iovec| {
sqe.opcode = IORING_OP_WRITEV as u8;
sqe.addr = iovecs.as_ptr() as *const _ as *const libc::c_void as u64;
sqe.len = iovecs.len() as u32;
sqe.__bindgen_anon_1.off = offset;
sqe.__bindgen_anon_3.__bindgen_anon_1.buf_index = 0;
sqe.ioprio = 0;
sqe.user_data = user_data;
sqe.flags = 0;
sqe.fd = fd;
})?;
self.complete_ring.add_op_data(user_data, iovecs);
Ok(())
}
/// See 'readv' but accepts an iterator instead of a vector if there isn't already a vector in
/// existence.
pub unsafe fn add_readv_iter<I>(
&mut self,
iovecs: I,
fd: RawFd,
offset: u64,
user_data: UserData,
) -> Result<()>
where
I: Iterator<Item = libc::iovec>,
{
self.add_readv(
Pin::from(iovecs.collect::<Vec<_>>().into_boxed_slice()),
fd,
offset,
user_data,
)
}
/// Asynchronously reads from `fd` to the addresses given in `iovecs`.
/// # Safety
/// `add_readv` will write to the address given by `iovecs`. This is only safe if the caller
/// guarantees there are no other references to that memory and that the memory lives until the
/// transaction is complete and that completion has been returned from the `wait` function. In
/// addition there must not be any references to the data pointed to by `iovecs` until the
/// operation completes. Ensure that the fd remains open until the op completes as well.
/// The iovecs reference must be kept alive until the op returns.
pub unsafe fn add_readv(
&mut self,
iovecs: Pin<Box<[libc::iovec]>>,
fd: RawFd,
offset: u64,
user_data: UserData,
) -> Result<()> {
self.prep_next_sqe(|sqe, _iovec| {
sqe.opcode = IORING_OP_READV as u8;
sqe.addr = iovecs.as_ptr() as *const _ as *const libc::c_void as u64;
sqe.len = iovecs.len() as u32;
sqe.__bindgen_anon_1.off = offset;
sqe.__bindgen_anon_3.__bindgen_anon_1.buf_index = 0;
sqe.ioprio = 0;
sqe.user_data = user_data;
sqe.flags = 0;
sqe.fd = fd;
})?;
self.complete_ring.add_op_data(user_data, iovecs);
Ok(())
}
/// Syncs all completed operations, the ordering with in-flight async ops is not
/// defined.
pub fn add_fsync(&mut self, fd: RawFd, user_data: UserData) -> Result<()> {
self.prep_next_sqe(|sqe, _iovec| {
sqe.opcode = IORING_OP_FSYNC as u8;
sqe.fd = fd;
sqe.user_data = user_data;
sqe.addr = 0;
sqe.len = 0;
sqe.__bindgen_anon_1.off = 0;
sqe.__bindgen_anon_3.__bindgen_anon_1.buf_index = 0;
sqe.__bindgen_anon_2.rw_flags = 0;
sqe.ioprio = 0;
sqe.flags = 0;
})
}
/// See the usage of `fallocate`, this asynchronously performs the same operations.
pub fn add_fallocate(
&mut self,
fd: RawFd,
offset: u64,
len: u64,
mode: u32,
user_data: UserData,
) -> Result<()> {
// Note that len for fallocate in passed in the addr field of the sqe and the mode uses the
// len field.
self.prep_next_sqe(|sqe, _iovec| {
sqe.opcode = IORING_OP_FALLOCATE as u8;
sqe.fd = fd;
sqe.addr = len;
sqe.len = mode;
sqe.__bindgen_anon_1.off = offset;
sqe.user_data = user_data;
sqe.__bindgen_anon_3.__bindgen_anon_1.buf_index = 0;
sqe.__bindgen_anon_2.rw_flags = 0;
sqe.ioprio = 0;
sqe.flags = 0;
})
}
/// Adds an FD to be polled based on the given flags.
/// The user must keep the FD open until the operation completion is returned from
/// `wait`.
/// Note that io_uring is always a one shot poll. After the fd is returned, it must be re-added
/// to get future events.
pub fn add_poll_fd(
&mut self,
fd: RawFd,
events: &WatchingEvents,
user_data: UserData,
) -> Result<()> {
self.prep_next_sqe(|sqe, _iovec| {
sqe.opcode = IORING_OP_POLL_ADD as u8;
sqe.fd = fd;
sqe.user_data = user_data;
sqe.__bindgen_anon_2.poll_events = events.get_raw() as u16;
sqe.addr = 0;
sqe.len = 0;
sqe.__bindgen_anon_1.off = 0;
sqe.__bindgen_anon_3.__bindgen_anon_1.buf_index = 0;
sqe.ioprio = 0;
sqe.flags = 0;
})
}
/// Removes an FD that was previously added with `add_poll_fd`.
pub fn remove_poll_fd(
&mut self,
fd: RawFd,
events: &WatchingEvents,
user_data: UserData,
) -> Result<()> {
self.prep_next_sqe(|sqe, _iovec| {
sqe.opcode = IORING_OP_POLL_REMOVE as u8;
sqe.fd = fd;
sqe.user_data = user_data;
sqe.__bindgen_anon_2.poll_events = events.get_raw() as u16;
sqe.addr = 0;
sqe.len = 0;
sqe.__bindgen_anon_1.off = 0;
sqe.__bindgen_anon_3.__bindgen_anon_1.buf_index = 0;
sqe.ioprio = 0;
sqe.flags = 0;
})
}
/// Sends operations added with the `add_*` functions to the kernel.
pub fn submit(&mut self) -> Result<()> {
self.in_flight += self.added;
self.stats.total_ops = self.stats.total_ops.wrapping_add(self.added as u64);
if self.added > 0 {
self.stats.total_enter_calls = self.stats.total_enter_calls.wrapping_add(1);
unsafe {
// Safe because the only memory modified is in the completion queue.
io_uring_enter(self.ring_file.as_raw_fd(), self.added as u64, 0, 0)
.map_err(Error::RingEnter)?;
}
}
self.added = 0;
Ok(())
}
/// Sends operations added with the `add_*` functions to the kernel and return an iterator to any
/// completed operations. `wait` blocks until at least one completion is ready. If called
/// without any new events added, this simply waits for any existing events to complete and
/// returns as soon an one or more is ready.
pub fn wait<'a>(
&'a mut self,
) -> Result<impl Iterator<Item = (UserData, std::io::Result<u32>)> + 'a> {
let completed = self.complete_ring.num_completed();
self.stats.total_complete = self.stats.total_complete.wrapping_add(completed as u64);
self.in_flight -= completed;
self.stats.total_ops = self.stats.total_ops.wrapping_add(self.added as u64);
if self.in_flight > 0 || self.added > 0 {
unsafe {
self.stats.total_enter_calls = self.stats.total_enter_calls.wrapping_add(1);
// Safe because the only memory modified is in the completion queue.
let ret = io_uring_enter(
self.ring_file.as_raw_fd(),
self.added as u64,
1,
IORING_ENTER_GETEVENTS,
);
match ret {
Ok(_) => {
self.in_flight += self.added;
self.added = 0;
}
Err(e) => {
if e != libc::EBUSY {
return Err(Error::RingEnter(e));
}
// An ebusy return means that some completed events must be processed before
// submitting more, wait for some to finish without pushing the new sqes in
// that case.
io_uring_enter(self.ring_file.as_raw_fd(), 0, 1, IORING_ENTER_GETEVENTS)
.map_err(Error::RingEnter)?;
}
}
}
}
// The CompletionQueue will iterate all completed ops.
Ok(&mut self.complete_ring)
}
}
impl AsRawFd for URingContext {
fn as_raw_fd(&self) -> RawFd {
self.ring_file.as_raw_fd()
}
}
struct SubmitQueueEntries {
mmap: MemoryMapping,
len: usize,
}
impl SubmitQueueEntries {
fn get_mut(&mut self, index: usize) -> Option<&mut io_uring_sqe> {
if index >= self.len {
return None;
}
let mut_ref = unsafe {
// Safe because the mut borrow of self resticts to one mutable reference at a time and
// we trust that the kernel has returned enough memory in io_uring_setup and mmap.
&mut *(self.mmap.as_ptr() as *mut io_uring_sqe).add(index)
};
// Clear any state.
*mut_ref = io_uring_sqe::default();
Some(mut_ref)
}
}
struct SubmitQueueState {
_mmap: MemoryMapping,
pointers: QueuePointers,
ring_mask: u32,
array: *mut u32,
}
impl SubmitQueueState {
// # Safety
// Safe iff `mmap` is created by mapping from a uring FD at the SQ_RING offset and params is
// the params struct passed to io_uring_setup.
unsafe fn new(mmap: MemoryMapping, params: &io_uring_params) -> SubmitQueueState {
let ptr = mmap.as_ptr();
// Transmutes are safe because a u32 is atomic on all supported architectures and the
// pointer will live until after self is dropped because the mmap is owned.
let head = ptr.add(params.sq_off.head as usize) as *const AtomicU32;
let tail = ptr.add(params.sq_off.tail as usize) as *const AtomicU32;
// This offset is guaranteed to be within the mmap so unwrap the result.
let ring_mask = mmap.read_obj(params.sq_off.ring_mask as usize).unwrap();
let array = ptr.add(params.sq_off.array as usize) as *mut u32;
SubmitQueueState {
_mmap: mmap,
pointers: QueuePointers { head, tail },
ring_mask,
array,
}
}
// Sets the kernel's array entry at the given `index` to `value`.
fn set_array_entry(&self, index: usize, value: u32) {
// Safe because self being constructed from the correct mmap guaratees that the memory is
// valid to written.
unsafe {
std::ptr::write_volatile(self.array.add(index), value as u32);
}
}
}
struct CompleteQueueState {
mmap: MemoryMapping,
pointers: QueuePointers,
ring_mask: u32,
cqes_offset: u32,
completed: usize,
//For ops that pass in arrays of iovecs, they need to be valid for the duration of the
//operation because the kernel might read them at any time.
pending_op_addrs: BTreeMap<UserData, Pin<Box<[libc::iovec]>>>,
}
impl CompleteQueueState {
/// # Safety
/// Safe iff `mmap` is created by mapping from a uring FD at the CQ_RING offset and params is
/// the params struct passed to io_uring_setup.
unsafe fn new(mmap: MemoryMapping, params: &io_uring_params) -> CompleteQueueState {
let ptr = mmap.as_ptr();
let head = ptr.add(params.cq_off.head as usize) as *const AtomicU32;
let tail = ptr.add(params.cq_off.tail as usize) as *const AtomicU32;
let ring_mask = mmap.read_obj(params.cq_off.ring_mask as usize).unwrap();
CompleteQueueState {
mmap,
pointers: QueuePointers { head, tail },
ring_mask,
cqes_offset: params.cq_off.cqes,
completed: 0,
pending_op_addrs: BTreeMap::new(),
}
}
fn add_op_data(&mut self, user_data: UserData, addrs: Pin<Box<[libc::iovec]>>) {
self.pending_op_addrs.insert(user_data, addrs);
}
fn get_cqe(&self, head: u32) -> &io_uring_cqe {
unsafe {
// Safe because we trust that the kernel has returned enough memory in io_uring_setup
// and mmap and index is checked within range by the ring_mask.
let cqes = (self.mmap.as_ptr() as *const u8).add(self.cqes_offset as usize)
as *const io_uring_cqe;
let index = head & self.ring_mask;
&*cqes.add(index as usize)
}
}
fn num_completed(&mut self) -> usize {
std::mem::replace(&mut self.completed, 0)
}
}
// Return the completed ops with their result.
impl Iterator for CompleteQueueState {
type Item = (UserData, std::io::Result<u32>);
fn next(&mut self) -> Option<Self::Item> {
// Safe because the pointers to the atomics are valid and the cqe must be in range
// because the kernel provided mask is applied to the index.
let head = self.pointers.head(Ordering::Relaxed);
// Synchronize the read of tail after the read of head.
if head == self.pointers.tail(Ordering::Acquire) {
return None;
}
self.completed += 1;
let cqe = self.get_cqe(head);
let user_data = cqe.user_data;
let res = cqe.res;
// free the addrs saved for this op.
let _ = self.pending_op_addrs.remove(&user_data);
// Store the new head and ensure the reads above complete before the kernel sees the
// update to head, `set_head` uses `Release` ordering
let new_head = head.wrapping_add(1);
self.pointers.set_head(new_head);
let io_res = match res {
r if r < 0 => Err(std::io::Error::from_raw_os_error(-r)),
r => Ok(r as u32),
};
Some((user_data, io_res))
}
}
struct QueuePointers {
head: *const AtomicU32,
tail: *const AtomicU32,
}
impl QueuePointers {
// Loads the tail pointer atomically with the given ordering.
fn tail(&self, ordering: Ordering) -> u32 {
// Safe because self being constructed from the correct mmap guaratees that the memory is
// valid to read.
unsafe { (*self.tail).load(ordering) }
}
// Stores the new value of the tail in the submit queue. This allows the kernel to start
// processing entries that have been added up until the given tail pointer.
// Always stores with release ordering as that is the only valid way to use the pointer.
fn set_tail(&self, next_tail: u32) {
// Safe because self being constructed from the correct mmap guaratees that the memory is
// valid to read and it's used as an atomic to cover mutability concerns.
unsafe { (*self.tail).store(next_tail, Ordering::Release) }
}
// Loads the head pointer atomically with the given ordering.
fn head(&self, ordering: Ordering) -> u32 {
// Safe because self being constructed from the correct mmap guaratees that the memory is
// valid to read.
unsafe { (*self.head).load(ordering) }
}
// Stores the new value of the head in the submit queue. This allows the kernel to start
// processing entries that have been added up until the given head pointer.
// Always stores with release ordering as that is the only valid way to use the pointer.
fn set_head(&self, next_head: u32) {
// Safe because self being constructed from the correct mmap guaratees that the memory is
// valid to read and it's used as an atomic to cover mutability concerns.
unsafe { (*self.head).store(next_head, Ordering::Release) }
}
}
#[cfg(test)]
mod tests {
use std::fs::OpenOptions;
use std::io::{IoSlice, IoSliceMut};
use std::io::{Read, Seek, SeekFrom, Write};
use std::path::{Path, PathBuf};
use std::time::Duration;
use sys_util::PollContext;
use tempfile::{tempfile, TempDir};
use super::*;
fn append_file_name(path: &Path, name: &str) -> PathBuf {
let mut joined = path.to_path_buf();
joined.push(name);
joined
}
fn check_one_read(
uring: &mut URingContext,
buf: &mut [u8],
fd: RawFd,
offset: u64,
user_data: UserData,
) {
let (user_data_ret, res) = unsafe {
// Safe because the `wait` call waits until the kernel is done with `buf`.
uring
.add_read(buf.as_mut_ptr(), buf.len(), fd, offset, user_data)
.unwrap();
uring.wait().unwrap().next().unwrap()
};
assert_eq!(user_data_ret, user_data);
assert_eq!(res.unwrap(), buf.len() as u32);
}
fn check_one_readv(
uring: &mut URingContext,
buf: &mut [u8],
fd: RawFd,
offset: u64,
user_data: UserData,
) {
let io_vecs = unsafe {
//safe to transmut from IoSlice to iovec.
vec![IoSliceMut::new(buf)]
.into_iter()
.map(|slice| std::mem::transmute::<IoSliceMut, libc::iovec>(slice))
};
let (user_data_ret, res) = unsafe {
// Safe because the `wait` call waits until the kernel is done with `buf`.
uring
.add_readv_iter(io_vecs, fd, offset, user_data)
.unwrap();
uring.wait().unwrap().next().unwrap()
};
assert_eq!(user_data_ret, user_data);
assert_eq!(res.unwrap(), buf.len() as u32);
}
fn create_test_file(size: u64) -> std::fs::File {
let f = tempfile().unwrap();
f.set_len(size).unwrap();
f
}
#[test]
// Queue as many reads as possible and then collect the completions.
fn read_parallel() {
const QUEUE_SIZE: usize = 10;
const BUF_SIZE: usize = 0x1000;
let mut uring = URingContext::new(QUEUE_SIZE).unwrap();
let mut buf = [0u8; BUF_SIZE * QUEUE_SIZE];
let f = create_test_file((BUF_SIZE * QUEUE_SIZE) as u64);
// check that the whole file can be read and that the queues wrapping is handled by reading
// double the quue depth of buffers.
for i in 0..QUEUE_SIZE * 64 {
let index = i as u64;
unsafe {
let offset = (i % QUEUE_SIZE) * BUF_SIZE;
match uring.add_read(
buf[offset..].as_mut_ptr(),
BUF_SIZE,
f.as_raw_fd(),
offset as u64,
index,
) {
Ok(_) => (),
Err(Error::NoSpace) => {
let _ = uring.wait().unwrap().next().unwrap();
}
Err(_) => panic!("unexpected error from uring wait"),
}
}
}
}
#[test]
fn read_readv() {
let queue_size = 128;
let mut uring = URingContext::new(queue_size).unwrap();
let mut buf = [0u8; 0x1000];
let f = create_test_file(0x1000 * 2);
// check that the whole file can be read and that the queues wrapping is handled by reading
// double the quue depth of buffers.
for i in 0..queue_size * 2 {
let index = i as u64;
check_one_read(
&mut uring,
&mut buf,
f.as_raw_fd(),
(index % 2) * 0x1000,
index,
);
check_one_readv(
&mut uring,
&mut buf,
f.as_raw_fd(),
(index % 2) * 0x1000,
index,
);
}
}
#[test]
fn readv_vec() {
let queue_size = 128;
const BUF_SIZE: usize = 0x2000;
let mut uring = URingContext::new(queue_size).unwrap();
let mut buf = [0u8; BUF_SIZE];
let mut buf2 = [0u8; BUF_SIZE];
let mut buf3 = [0u8; BUF_SIZE];
let io_vecs = unsafe {
//safe to transmut from IoSlice to iovec.
vec![
IoSliceMut::new(&mut buf),
IoSliceMut::new(&mut buf2),
IoSliceMut::new(&mut buf3),
]
.into_iter()
.map(|slice| std::mem::transmute::<IoSliceMut, libc::iovec>(slice))
.collect::<Vec<libc::iovec>>()
};
let total_len = io_vecs.iter().fold(0, |a, iovec| a + iovec.iov_len);
let f = create_test_file(total_len as u64 * 2);
let (user_data_ret, res) = unsafe {
// Safe because the `wait` call waits until the kernel is done with `buf`.
uring
.add_readv_iter(io_vecs.into_iter(), f.as_raw_fd(), 0, 55)
.unwrap();
uring.wait().unwrap().next().unwrap()
};
assert_eq!(user_data_ret, 55);
assert_eq!(res.unwrap(), total_len as u32);
}
#[test]
fn write_one_block() {
let mut uring = URingContext::new(16).unwrap();
let mut buf = [0u8; 4096];
let mut f = create_test_file(0);
f.write(&buf).unwrap();
f.write(&buf).unwrap();
unsafe {
// Safe because the `wait` call waits until the kernel is done mutating `buf`.
uring
.add_write(buf.as_mut_ptr(), buf.len(), f.as_raw_fd(), 0, 55)
.unwrap();
let (user_data, res) = uring.wait().unwrap().next().unwrap();
assert_eq!(user_data, 55 as UserData);
assert_eq!(res.unwrap(), buf.len() as u32);
}
}
#[test]
fn write_one_submit_poll() {
let mut uring = URingContext::new(16).unwrap();
let mut buf = [0u8; 4096];
let mut f = create_test_file(0);
f.write(&buf).unwrap();
f.write(&buf).unwrap();
let ctx: PollContext<u64> = PollContext::build_with(&[(&uring, 1)]).unwrap();
{
// Test that the uring context isn't readable before any events are complete.
let events = ctx.wait_timeout(Duration::from_millis(1)).unwrap();
assert!(events.iter_readable().next().is_none());
}
unsafe {
// Safe because the `wait` call waits until the kernel is done mutating `buf`.
uring
.add_write(buf.as_mut_ptr(), buf.len(), f.as_raw_fd(), 0, 55)
.unwrap();
uring.submit().unwrap();
// Poll for completion with epoll.
let events = ctx.wait().unwrap();
let event = events.iter_readable().next().unwrap();
assert_eq!(event.token(), 1);
let (user_data, res) = uring.wait().unwrap().next().unwrap();
assert_eq!(user_data, 55 as UserData);
assert_eq!(res.unwrap(), buf.len() as u32);
}
}
#[test]
fn writev_vec() {
let queue_size = 128;
const BUF_SIZE: usize = 0x2000;
const OFFSET: u64 = 0x2000;
let mut uring = URingContext::new(queue_size).unwrap();
let buf = [0xaau8; BUF_SIZE];
let buf2 = [0xffu8; BUF_SIZE];
let buf3 = [0x55u8; BUF_SIZE];
let io_vecs = unsafe {
//safe to transmut from IoSlice to iovec.
vec![IoSlice::new(&buf), IoSlice::new(&buf2), IoSlice::new(&buf3)]
.into_iter()
.map(|slice| std::mem::transmute::<IoSlice, libc::iovec>(slice))
.collect::<Vec<libc::iovec>>()
};
let total_len = io_vecs.iter().fold(0, |a, iovec| a + iovec.iov_len);
let mut f = create_test_file(total_len as u64 * 2);
let (user_data_ret, res) = unsafe {
// Safe because the `wait` call waits until the kernel is done with `buf`.
uring
.add_writev_iter(io_vecs.into_iter(), f.as_raw_fd(), OFFSET, 55)
.unwrap();
uring.wait().unwrap().next().unwrap()
};
assert_eq!(user_data_ret, 55);
assert_eq!(res.unwrap(), total_len as u32);
let mut read_back = [0u8; BUF_SIZE];
f.seek(SeekFrom::Start(OFFSET)).unwrap();
f.read(&mut read_back).unwrap();
assert!(!read_back.iter().any(|&b| b != 0xaa));
f.read(&mut read_back).unwrap();
assert!(!read_back.iter().any(|&b| b != 0xff));
f.read(&mut read_back).unwrap();
assert!(!read_back.iter().any(|&b| b != 0x55));
}
#[test]
fn fallocate_fsync() {
let tempdir = TempDir::new().unwrap();
let file_path = append_file_name(tempdir.path(), "test");
{
let buf = [0u8; 4096];
let mut f = OpenOptions::new()
.read(true)
.write(true)
.create(true)
.truncate(true)
.open(&file_path)
.unwrap();
f.write(&buf).unwrap();
}
let init_size = std::fs::metadata(&file_path).unwrap().len() as usize;
let set_size = init_size + 1024 * 1024 * 50;
let f = OpenOptions::new()
.read(true)
.write(true)
.create(true)
.open(&file_path)
.unwrap();
let mut uring = URingContext::new(16).unwrap();
uring
.add_fallocate(f.as_raw_fd(), 0, set_size as u64, 0, 66)
.unwrap();
let (user_data, res) = uring.wait().unwrap().next().unwrap();
assert_eq!(user_data, 66 as UserData);
match res {
Err(e) => {
if e.kind() == std::io::ErrorKind::InvalidInput {
// skip on kernels that don't support fallocate.
return;
}
panic!("Unexpected fallocate error: {}", e);
}
Ok(val) => assert_eq!(val, 0 as u32),
}
// Add a few writes and then fsync
let buf = [0u8; 4096];
let mut pending = std::collections::BTreeSet::new();
unsafe {
uring
.add_write(buf.as_ptr(), buf.len(), f.as_raw_fd(), 0, 67)
.unwrap();
pending.insert(67u64);
uring
.add_write(buf.as_ptr(), buf.len(), f.as_raw_fd(), 4096, 68)
.unwrap();
pending.insert(68);
uring
.add_write(buf.as_ptr(), buf.len(), f.as_raw_fd(), 8192, 69)
.unwrap();
pending.insert(69);
}
uring.add_fsync(f.as_raw_fd(), 70).unwrap();
pending.insert(70);
let mut wait_calls = 0;
while !pending.is_empty() && wait_calls < 5 {
let events = uring.wait().unwrap();
for (user_data, res) in events {
assert!(res.is_ok());
assert!(pending.contains(&user_data));
pending.remove(&user_data);
}
wait_calls += 1;
}
assert!(pending.is_empty());
uring
.add_fallocate(
f.as_raw_fd(),
init_size as u64,
(set_size - init_size) as u64,
(libc::FALLOC_FL_PUNCH_HOLE | libc::FALLOC_FL_KEEP_SIZE) as u32,
68,
)
.unwrap();
let (user_data, res) = uring.wait().unwrap().next().unwrap();
assert_eq!(user_data, 68 as UserData);
assert_eq!(res.unwrap(), 0 as u32);
drop(f); // Close to ensure directory entires for metadata are updated.
let new_size = std::fs::metadata(&file_path).unwrap().len() as usize;
assert_eq!(new_size, set_size);
}
#[test]
fn dev_zero_readable() {
let f = File::open(Path::new("/dev/zero")).unwrap();
let mut uring = URingContext::new(16).unwrap();
uring
.add_poll_fd(f.as_raw_fd(), &WatchingEvents::empty().set_read(), 454)
.unwrap();
let (user_data, res) = uring.wait().unwrap().next().unwrap();
assert_eq!(user_data, 454 as UserData);
assert_eq!(res.unwrap(), 1 as u32);
}
#[test]
fn queue_many_ebusy_retry() {
let num_entries = 16;
let f = File::open(Path::new("/dev/zero")).unwrap();
let mut uring = URingContext::new(num_entries).unwrap();
// Fill the sumbit ring.
for sqe_batch in 0..3 {
for i in 0..num_entries {
uring
.add_poll_fd(
f.as_raw_fd(),
&WatchingEvents::empty().set_read(),
(sqe_batch * num_entries + i) as u64,
)
.unwrap();
}
uring.submit().unwrap();
}
// Adding more than the number of cqes will cause the uring to return ebusy, make sure that
// is handled cleanly and wait still returns the completed entries.
uring
.add_poll_fd(
f.as_raw_fd(),
&WatchingEvents::empty().set_read(),
(num_entries * 3) as u64,
)
.unwrap();
// The first wait call should return the cques that are already filled.
{
let mut results = uring.wait().unwrap();
for _i in 0..num_entries * 2 {
assert_eq!(results.next().unwrap().1.unwrap(), 1 as u32);
}
assert!(results.next().is_none());
}
// The second will finish submitting any more sqes and return the rest.
let mut results = uring.wait().unwrap();
for _i in 0..num_entries + 1 {
assert_eq!(results.next().unwrap().1.unwrap(), 1 as u32);
}
assert!(results.next().is_none());
}
}
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