This function will register the fd handler similar to
aio_set_event_notifier, but the difference is the fd will only be polled
in the outmost aio_poll.
This is useful in some cases like device ioeventfd, where the handler
typically processes a guest request, therefore nested aio_poll shouldn't
include this.
Signed-off-by: Fam Zheng <f...@redhat.com>
---
aio-posix.c | 33 +++++++++++++++++++++++++++------
include/block/aio.h | 23 ++++++++++++++++++++---
2 files changed, 47 insertions(+), 9 deletions(-)
diff --git a/aio-posix.c b/aio-posix.c
index 4abec38..05a0502 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -24,6 +24,7 @@ struct AioHandler
IOHandler *io_read;
IOHandler *io_write;
int deleted;
+ bool outmost;
void *opaque;
QLIST_ENTRY(AioHandler) node;
};
@@ -41,11 +42,12 @@ static AioHandler *find_aio_handler(AioContext *ctx, int fd)
return NULL;
}
-void aio_set_fd_handler(AioContext *ctx,
- int fd,
- IOHandler *io_read,
- IOHandler *io_write,
- void *opaque)
+static void aio_set_fd_handler_do(AioContext *ctx,
+ int fd,
+ IOHandler *io_read,
+ IOHandler *io_write,
+ void *opaque,
+ bool outmost)
{
AioHandler *node;
@@ -82,6 +84,7 @@ void aio_set_fd_handler(AioContext *ctx,
node->io_read = io_read;
node->io_write = io_write;
node->opaque = opaque;
+ node->outmost = outmost;
node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP | G_IO_ERR : 0);
node->pfd.events |= (io_write ? G_IO_OUT | G_IO_ERR : 0);
@@ -90,6 +93,15 @@ void aio_set_fd_handler(AioContext *ctx,
aio_notify(ctx);
}
+void aio_set_fd_handler(AioContext *ctx,
+ int fd,
+ IOHandler *io_read,
+ IOHandler *io_write,
+ void *opaque)
+{
+ aio_set_fd_handler_do(ctx, fd, io_read, io_write, opaque, false);
+}
+
void aio_set_event_notifier(AioContext *ctx,
EventNotifier *notifier,
EventNotifierHandler *io_read)
@@ -98,6 +110,14 @@ void aio_set_event_notifier(AioContext *ctx,
(IOHandler *)io_read, NULL, notifier);
}
+void aio_set_io_event_notifier(AioContext *ctx,
+ EventNotifier *notifier,
+ EventNotifierHandler *io_read)
+{
+ aio_set_fd_handler_do(ctx, event_notifier_get_fd(notifier),
+ (IOHandler *)io_read, NULL, notifier, true);
+}
+
bool aio_prepare(AioContext *ctx)
{
return false;
@@ -260,7 +280,8 @@ bool aio_poll(AioContext *ctx, bool blocking)
/* fill pollfds */
QLIST_FOREACH(node, &ctx->aio_handlers, node) {
- if (!node->deleted && node->pfd.events) {
+ if (!node->deleted && node->pfd.events
+ && !(was_dispatching && node->outmost)) {
add_pollfd(node);
}
}
diff --git a/include/block/aio.h b/include/block/aio.h
index d2bb423..20bfb2b 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -240,9 +240,7 @@ bool aio_dispatch(AioContext *ctx);
*/
bool aio_poll(AioContext *ctx, bool blocking);
-/* Register a file descriptor and associated callbacks. Behaves very similarly
- * to qemu_set_fd_handler2. Unlike qemu_set_fd_handler2, these callbacks will
- * be invoked when using aio_poll().
+/* Register a file descriptor and associated callbacks.
*
* Code that invokes AIO completion functions should rely on this function
* instead of qemu_set_fd_handler[2].
@@ -253,6 +251,15 @@ void aio_set_fd_handler(AioContext *ctx,
IOHandler *io_write,
void *opaque);
+/* Register a file descriptor and associated callbacks. Behaves very similarly
+ * to qemu_set_fd_handler: these callbacks will be invoked only by outmost
+ * aio_poll() directly, but not in nested polls (such as bdrv_drain() or
+ * bdrv_aio_cancel()).
+ */
+void aio_set_iohandler(AioContext *ctx, int fd,
+ IOHandler *io_read,
+ IOHandler *io_write,
+ void *opaque);
/* Register an event notifier and associated callbacks. Behaves very similarly
* to event_notifier_set_handler. Unlike event_notifier_set_handler, these
callbacks
* will be invoked when using aio_poll().
@@ -264,6 +271,16 @@ void aio_set_event_notifier(AioContext *ctx,
EventNotifier *notifier,
EventNotifierHandler *io_read);
+/* Similar to aio_set_event_notifier except the notifier will only be checked
+ * in top level poll.
+ *
+ * Notifiers for external requests like guest I/O or monitor command should use
+ * this function.
+ */
+void aio_set_io_event_notifier(AioContext *ctx,
+ EventNotifier *notifier,
+ EventNotifierHandler *io_read);
+
/* Return a GSource that lets the main loop poll the file descriptors attached
* to this AioContext.
*/
--
2.4.1
