mirror of
https://gitlab.com/qemu-project/qemu
synced 2024-09-06 18:05:37 +00:00
![Jinhao Fan](/assets/img/avatar_default.png)
The commit "Use io_uring_register_ring_fd() to skip fd operations" uses
warn_report but did not include the header file "qemu/error-report.h".
This causes "error: implicit declaration of function ‘warn_report’".
Include this header file.
Fixes: e2848bc574
("Use io_uring_register_ring_fd() to skip fd operations")
Signed-off-by: Jinhao Fan <fanjinhao21s@ict.ac.cn>
Message-Id: <20220721065645.577404-1-fanjinhao21s@ict.ac.cn>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
454 lines
13 KiB
C
454 lines
13 KiB
C
/*
|
|
* Linux io_uring support.
|
|
*
|
|
* Copyright (C) 2009 IBM, Corp.
|
|
* Copyright (C) 2009 Red Hat, Inc.
|
|
* Copyright (C) 2019 Aarushi Mehta
|
|
*
|
|
* This work is licensed under the terms of the GNU GPL, version 2 or later.
|
|
* See the COPYING file in the top-level directory.
|
|
*/
|
|
#include "qemu/osdep.h"
|
|
#include <liburing.h>
|
|
#include "block/aio.h"
|
|
#include "qemu/error-report.h"
|
|
#include "qemu/queue.h"
|
|
#include "block/block.h"
|
|
#include "block/raw-aio.h"
|
|
#include "qemu/coroutine.h"
|
|
#include "qapi/error.h"
|
|
#include "trace.h"
|
|
|
|
|
|
/* io_uring ring size */
|
|
#define MAX_ENTRIES 128
|
|
|
|
typedef struct LuringAIOCB {
|
|
Coroutine *co;
|
|
struct io_uring_sqe sqeq;
|
|
ssize_t ret;
|
|
QEMUIOVector *qiov;
|
|
bool is_read;
|
|
QSIMPLEQ_ENTRY(LuringAIOCB) next;
|
|
|
|
/*
|
|
* Buffered reads may require resubmission, see
|
|
* luring_resubmit_short_read().
|
|
*/
|
|
int total_read;
|
|
QEMUIOVector resubmit_qiov;
|
|
} LuringAIOCB;
|
|
|
|
typedef struct LuringQueue {
|
|
int plugged;
|
|
unsigned int in_queue;
|
|
unsigned int in_flight;
|
|
bool blocked;
|
|
QSIMPLEQ_HEAD(, LuringAIOCB) submit_queue;
|
|
} LuringQueue;
|
|
|
|
typedef struct LuringState {
|
|
AioContext *aio_context;
|
|
|
|
struct io_uring ring;
|
|
|
|
/* io queue for submit at batch. Protected by AioContext lock. */
|
|
LuringQueue io_q;
|
|
|
|
/* I/O completion processing. Only runs in I/O thread. */
|
|
QEMUBH *completion_bh;
|
|
} LuringState;
|
|
|
|
/**
|
|
* luring_resubmit:
|
|
*
|
|
* Resubmit a request by appending it to submit_queue. The caller must ensure
|
|
* that ioq_submit() is called later so that submit_queue requests are started.
|
|
*/
|
|
static void luring_resubmit(LuringState *s, LuringAIOCB *luringcb)
|
|
{
|
|
QSIMPLEQ_INSERT_TAIL(&s->io_q.submit_queue, luringcb, next);
|
|
s->io_q.in_queue++;
|
|
}
|
|
|
|
/**
|
|
* luring_resubmit_short_read:
|
|
*
|
|
* Short reads are rare but may occur. The remaining read request needs to be
|
|
* resubmitted.
|
|
*/
|
|
static void luring_resubmit_short_read(LuringState *s, LuringAIOCB *luringcb,
|
|
int nread)
|
|
{
|
|
QEMUIOVector *resubmit_qiov;
|
|
size_t remaining;
|
|
|
|
trace_luring_resubmit_short_read(s, luringcb, nread);
|
|
|
|
/* Update read position */
|
|
luringcb->total_read += nread;
|
|
remaining = luringcb->qiov->size - luringcb->total_read;
|
|
|
|
/* Shorten qiov */
|
|
resubmit_qiov = &luringcb->resubmit_qiov;
|
|
if (resubmit_qiov->iov == NULL) {
|
|
qemu_iovec_init(resubmit_qiov, luringcb->qiov->niov);
|
|
} else {
|
|
qemu_iovec_reset(resubmit_qiov);
|
|
}
|
|
qemu_iovec_concat(resubmit_qiov, luringcb->qiov, luringcb->total_read,
|
|
remaining);
|
|
|
|
/* Update sqe */
|
|
luringcb->sqeq.off += nread;
|
|
luringcb->sqeq.addr = (__u64)(uintptr_t)luringcb->resubmit_qiov.iov;
|
|
luringcb->sqeq.len = luringcb->resubmit_qiov.niov;
|
|
|
|
luring_resubmit(s, luringcb);
|
|
}
|
|
|
|
/**
|
|
* luring_process_completions:
|
|
* @s: AIO state
|
|
*
|
|
* Fetches completed I/O requests, consumes cqes and invokes their callbacks
|
|
* The function is somewhat tricky because it supports nested event loops, for
|
|
* example when a request callback invokes aio_poll().
|
|
*
|
|
* Function schedules BH completion so it can be called again in a nested
|
|
* event loop. When there are no events left to complete the BH is being
|
|
* canceled.
|
|
*
|
|
*/
|
|
static void luring_process_completions(LuringState *s)
|
|
{
|
|
struct io_uring_cqe *cqes;
|
|
int total_bytes;
|
|
/*
|
|
* Request completion callbacks can run the nested event loop.
|
|
* Schedule ourselves so the nested event loop will "see" remaining
|
|
* completed requests and process them. Without this, completion
|
|
* callbacks that wait for other requests using a nested event loop
|
|
* would hang forever.
|
|
*
|
|
* This workaround is needed because io_uring uses poll_wait, which
|
|
* is woken up when new events are added to the uring, thus polling on
|
|
* the same uring fd will block unless more events are received.
|
|
*
|
|
* Other leaf block drivers (drivers that access the data themselves)
|
|
* are networking based, so they poll sockets for data and run the
|
|
* correct coroutine.
|
|
*/
|
|
qemu_bh_schedule(s->completion_bh);
|
|
|
|
while (io_uring_peek_cqe(&s->ring, &cqes) == 0) {
|
|
LuringAIOCB *luringcb;
|
|
int ret;
|
|
|
|
if (!cqes) {
|
|
break;
|
|
}
|
|
|
|
luringcb = io_uring_cqe_get_data(cqes);
|
|
ret = cqes->res;
|
|
io_uring_cqe_seen(&s->ring, cqes);
|
|
cqes = NULL;
|
|
|
|
/* Change counters one-by-one because we can be nested. */
|
|
s->io_q.in_flight--;
|
|
trace_luring_process_completion(s, luringcb, ret);
|
|
|
|
/* total_read is non-zero only for resubmitted read requests */
|
|
total_bytes = ret + luringcb->total_read;
|
|
|
|
if (ret < 0) {
|
|
/*
|
|
* Only writev/readv/fsync requests on regular files or host block
|
|
* devices are submitted. Therefore -EAGAIN is not expected but it's
|
|
* known to happen sometimes with Linux SCSI. Submit again and hope
|
|
* the request completes successfully.
|
|
*
|
|
* For more information, see:
|
|
* https://lore.kernel.org/io-uring/20210727165811.284510-3-axboe@kernel.dk/T/#u
|
|
*
|
|
* If the code is changed to submit other types of requests in the
|
|
* future, then this workaround may need to be extended to deal with
|
|
* genuine -EAGAIN results that should not be resubmitted
|
|
* immediately.
|
|
*/
|
|
if (ret == -EINTR || ret == -EAGAIN) {
|
|
luring_resubmit(s, luringcb);
|
|
continue;
|
|
}
|
|
} else if (!luringcb->qiov) {
|
|
goto end;
|
|
} else if (total_bytes == luringcb->qiov->size) {
|
|
ret = 0;
|
|
/* Only read/write */
|
|
} else {
|
|
/* Short Read/Write */
|
|
if (luringcb->is_read) {
|
|
if (ret > 0) {
|
|
luring_resubmit_short_read(s, luringcb, ret);
|
|
continue;
|
|
} else {
|
|
/* Pad with zeroes */
|
|
qemu_iovec_memset(luringcb->qiov, total_bytes, 0,
|
|
luringcb->qiov->size - total_bytes);
|
|
ret = 0;
|
|
}
|
|
} else {
|
|
ret = -ENOSPC;
|
|
}
|
|
}
|
|
end:
|
|
luringcb->ret = ret;
|
|
qemu_iovec_destroy(&luringcb->resubmit_qiov);
|
|
|
|
/*
|
|
* If the coroutine is already entered it must be in ioq_submit()
|
|
* and will notice luringcb->ret has been filled in when it
|
|
* eventually runs later. Coroutines cannot be entered recursively
|
|
* so avoid doing that!
|
|
*/
|
|
if (!qemu_coroutine_entered(luringcb->co)) {
|
|
aio_co_wake(luringcb->co);
|
|
}
|
|
}
|
|
qemu_bh_cancel(s->completion_bh);
|
|
}
|
|
|
|
static int ioq_submit(LuringState *s)
|
|
{
|
|
int ret = 0;
|
|
LuringAIOCB *luringcb, *luringcb_next;
|
|
|
|
while (s->io_q.in_queue > 0) {
|
|
/*
|
|
* Try to fetch sqes from the ring for requests waiting in
|
|
* the overflow queue
|
|
*/
|
|
QSIMPLEQ_FOREACH_SAFE(luringcb, &s->io_q.submit_queue, next,
|
|
luringcb_next) {
|
|
struct io_uring_sqe *sqes = io_uring_get_sqe(&s->ring);
|
|
if (!sqes) {
|
|
break;
|
|
}
|
|
/* Prep sqe for submission */
|
|
*sqes = luringcb->sqeq;
|
|
QSIMPLEQ_REMOVE_HEAD(&s->io_q.submit_queue, next);
|
|
}
|
|
ret = io_uring_submit(&s->ring);
|
|
trace_luring_io_uring_submit(s, ret);
|
|
/* Prevent infinite loop if submission is refused */
|
|
if (ret <= 0) {
|
|
if (ret == -EAGAIN || ret == -EINTR) {
|
|
continue;
|
|
}
|
|
break;
|
|
}
|
|
s->io_q.in_flight += ret;
|
|
s->io_q.in_queue -= ret;
|
|
}
|
|
s->io_q.blocked = (s->io_q.in_queue > 0);
|
|
|
|
if (s->io_q.in_flight) {
|
|
/*
|
|
* We can try to complete something just right away if there are
|
|
* still requests in-flight.
|
|
*/
|
|
luring_process_completions(s);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static void luring_process_completions_and_submit(LuringState *s)
|
|
{
|
|
aio_context_acquire(s->aio_context);
|
|
luring_process_completions(s);
|
|
|
|
if (!s->io_q.plugged && s->io_q.in_queue > 0) {
|
|
ioq_submit(s);
|
|
}
|
|
aio_context_release(s->aio_context);
|
|
}
|
|
|
|
static void qemu_luring_completion_bh(void *opaque)
|
|
{
|
|
LuringState *s = opaque;
|
|
luring_process_completions_and_submit(s);
|
|
}
|
|
|
|
static void qemu_luring_completion_cb(void *opaque)
|
|
{
|
|
LuringState *s = opaque;
|
|
luring_process_completions_and_submit(s);
|
|
}
|
|
|
|
static bool qemu_luring_poll_cb(void *opaque)
|
|
{
|
|
LuringState *s = opaque;
|
|
|
|
return io_uring_cq_ready(&s->ring);
|
|
}
|
|
|
|
static void qemu_luring_poll_ready(void *opaque)
|
|
{
|
|
LuringState *s = opaque;
|
|
|
|
luring_process_completions_and_submit(s);
|
|
}
|
|
|
|
static void ioq_init(LuringQueue *io_q)
|
|
{
|
|
QSIMPLEQ_INIT(&io_q->submit_queue);
|
|
io_q->plugged = 0;
|
|
io_q->in_queue = 0;
|
|
io_q->in_flight = 0;
|
|
io_q->blocked = false;
|
|
}
|
|
|
|
void luring_io_plug(BlockDriverState *bs, LuringState *s)
|
|
{
|
|
trace_luring_io_plug(s);
|
|
s->io_q.plugged++;
|
|
}
|
|
|
|
void luring_io_unplug(BlockDriverState *bs, LuringState *s)
|
|
{
|
|
assert(s->io_q.plugged);
|
|
trace_luring_io_unplug(s, s->io_q.blocked, s->io_q.plugged,
|
|
s->io_q.in_queue, s->io_q.in_flight);
|
|
if (--s->io_q.plugged == 0 &&
|
|
!s->io_q.blocked && s->io_q.in_queue > 0) {
|
|
ioq_submit(s);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* luring_do_submit:
|
|
* @fd: file descriptor for I/O
|
|
* @luringcb: AIO control block
|
|
* @s: AIO state
|
|
* @offset: offset for request
|
|
* @type: type of request
|
|
*
|
|
* Fetches sqes from ring, adds to pending queue and preps them
|
|
*
|
|
*/
|
|
static int luring_do_submit(int fd, LuringAIOCB *luringcb, LuringState *s,
|
|
uint64_t offset, int type)
|
|
{
|
|
int ret;
|
|
struct io_uring_sqe *sqes = &luringcb->sqeq;
|
|
|
|
switch (type) {
|
|
case QEMU_AIO_WRITE:
|
|
io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
|
|
luringcb->qiov->niov, offset);
|
|
break;
|
|
case QEMU_AIO_READ:
|
|
io_uring_prep_readv(sqes, fd, luringcb->qiov->iov,
|
|
luringcb->qiov->niov, offset);
|
|
break;
|
|
case QEMU_AIO_FLUSH:
|
|
io_uring_prep_fsync(sqes, fd, IORING_FSYNC_DATASYNC);
|
|
break;
|
|
default:
|
|
fprintf(stderr, "%s: invalid AIO request type, aborting 0x%x.\n",
|
|
__func__, type);
|
|
abort();
|
|
}
|
|
io_uring_sqe_set_data(sqes, luringcb);
|
|
|
|
QSIMPLEQ_INSERT_TAIL(&s->io_q.submit_queue, luringcb, next);
|
|
s->io_q.in_queue++;
|
|
trace_luring_do_submit(s, s->io_q.blocked, s->io_q.plugged,
|
|
s->io_q.in_queue, s->io_q.in_flight);
|
|
if (!s->io_q.blocked &&
|
|
(!s->io_q.plugged ||
|
|
s->io_q.in_flight + s->io_q.in_queue >= MAX_ENTRIES)) {
|
|
ret = ioq_submit(s);
|
|
trace_luring_do_submit_done(s, ret);
|
|
return ret;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int coroutine_fn luring_co_submit(BlockDriverState *bs, LuringState *s, int fd,
|
|
uint64_t offset, QEMUIOVector *qiov, int type)
|
|
{
|
|
int ret;
|
|
LuringAIOCB luringcb = {
|
|
.co = qemu_coroutine_self(),
|
|
.ret = -EINPROGRESS,
|
|
.qiov = qiov,
|
|
.is_read = (type == QEMU_AIO_READ),
|
|
};
|
|
trace_luring_co_submit(bs, s, &luringcb, fd, offset, qiov ? qiov->size : 0,
|
|
type);
|
|
ret = luring_do_submit(fd, &luringcb, s, offset, type);
|
|
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
if (luringcb.ret == -EINPROGRESS) {
|
|
qemu_coroutine_yield();
|
|
}
|
|
return luringcb.ret;
|
|
}
|
|
|
|
void luring_detach_aio_context(LuringState *s, AioContext *old_context)
|
|
{
|
|
aio_set_fd_handler(old_context, s->ring.ring_fd, false,
|
|
NULL, NULL, NULL, NULL, s);
|
|
qemu_bh_delete(s->completion_bh);
|
|
s->aio_context = NULL;
|
|
}
|
|
|
|
void luring_attach_aio_context(LuringState *s, AioContext *new_context)
|
|
{
|
|
s->aio_context = new_context;
|
|
s->completion_bh = aio_bh_new(new_context, qemu_luring_completion_bh, s);
|
|
aio_set_fd_handler(s->aio_context, s->ring.ring_fd, false,
|
|
qemu_luring_completion_cb, NULL,
|
|
qemu_luring_poll_cb, qemu_luring_poll_ready, s);
|
|
}
|
|
|
|
LuringState *luring_init(Error **errp)
|
|
{
|
|
int rc;
|
|
LuringState *s = g_new0(LuringState, 1);
|
|
struct io_uring *ring = &s->ring;
|
|
|
|
trace_luring_init_state(s, sizeof(*s));
|
|
|
|
rc = io_uring_queue_init(MAX_ENTRIES, ring, 0);
|
|
if (rc < 0) {
|
|
error_setg_errno(errp, errno, "failed to init linux io_uring ring");
|
|
g_free(s);
|
|
return NULL;
|
|
}
|
|
|
|
ioq_init(&s->io_q);
|
|
#ifdef CONFIG_LIBURING_REGISTER_RING_FD
|
|
if (io_uring_register_ring_fd(&s->ring) < 0) {
|
|
/*
|
|
* Only warn about this error: we will fallback to the non-optimized
|
|
* io_uring operations.
|
|
*/
|
|
warn_report("failed to register linux io_uring ring file descriptor");
|
|
}
|
|
#endif
|
|
|
|
return s;
|
|
}
|
|
|
|
void luring_cleanup(LuringState *s)
|
|
{
|
|
io_uring_queue_exit(&s->ring);
|
|
trace_luring_cleanup_state(s);
|
|
g_free(s);
|
|
}
|