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win32-aio: Run CB in original context

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AIO callbacks must be called in the originally calling AioContext,
regardless of the BDS’s “main” AioContext.

Note: I tried to test this (under wine), but failed.  Whenever I tried
to use multiqueue or even just an I/O thread for a virtio-blk (or
virtio-scsi) device, I/O stalled, both with and without this patch.

For what it’s worth, when not using an I/O thread, I/O continued to work
with this patch.

Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
Message-ID: <20251110154854.151484-20-hreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Hanna Czenczek 2025-11-10 16:48:54 +01:00 • committed by Kevin Wolf
parent f18782a8f5
commit 837c04e9fc
1 changed files with 24 additions and 7 deletions
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31
block/win32-aio.c
View file

@ -48,48 +48,62 @@ struct QEMUWin32AIOState {
typedef struct QEMUWin32AIOCB {
BlockAIOCB common;
struct QEMUWin32AIOState *ctx;
AioContext *req_ctx;
int nbytes;
OVERLAPPED ov;
QEMUIOVector *qiov;
void *buf;
bool is_read;
bool is_linear;
int ret;
} QEMUWin32AIOCB;
static void win32_aio_completion_cb_bh(void *opaque)
{
QEMUWin32AIOCB *waiocb = opaque;
waiocb->common.cb(waiocb->common.opaque, waiocb->ret);
aio_context_unref(waiocb->req_ctx);
qemu_aio_unref(waiocb);
}
/*
* Completes an AIO request (calls the callback and frees the ACB).
*/
static void win32_aio_process_completion(QEMUWin32AIOState *s,
QEMUWin32AIOCB *waiocb, DWORD count)
{
int ret;
s->count--;
if (waiocb->ov.Internal != 0) {
ret = -EIO;
waiocb->ret = -EIO;
} else {
ret = 0;
waiocb->ret = 0;
if (count < waiocb->nbytes) {
/* Short reads mean EOF, pad with zeros. */
if (waiocb->is_read) {
qemu_iovec_memset(waiocb->qiov, count, 0,
waiocb->qiov->size - count);
} else {
ret = -EINVAL;
waiocb->ret = -EINVAL;
}
}
}
if (!waiocb->is_linear) {
if (ret == 0 && waiocb->is_read) {
if (waiocb->ret == 0 && waiocb->is_read) {
QEMUIOVector *qiov = waiocb->qiov;
iov_from_buf(qiov->iov, qiov->niov, 0, waiocb->buf, qiov->size);
}
qemu_vfree(waiocb->buf);
}
waiocb->common.cb(waiocb->common.opaque, ret);
qemu_aio_unref(waiocb);
if (waiocb->req_ctx == s->aio_ctx) {
win32_aio_completion_cb_bh(waiocb);
} else {
aio_bh_schedule_oneshot(waiocb->req_ctx, win32_aio_completion_cb_bh,
waiocb);
}
}
static void win32_aio_completion_cb(EventNotifier *e)
@ -120,10 +134,13 @@ BlockAIOCB *win32_aio_submit(BlockDriverState *bs,
DWORD rc;
waiocb = qemu_aio_get(&win32_aiocb_info, bs, cb, opaque);
waiocb->req_ctx = qemu_get_current_aio_context();
waiocb->nbytes = bytes;
waiocb->qiov = qiov;
waiocb->is_read = (type == QEMU_AIO_READ);
aio_context_ref(waiocb->req_ctx);
if (qiov->niov > 1) {
waiocb->buf = qemu_try_blockalign(bs, qiov->size);
if (waiocb->buf == NULL) {