diff --git a/server/device.c b/server/device.c
index 1479a1ca38f..d5574ae325f 100644
--- a/server/device.c
+++ b/server/device.c
@@ -176,7 +176,7 @@ static void device_file_destroy( struct object *obj );
 static enum server_fd_type device_file_get_fd_type( struct fd *fd );
 static obj_handle_t device_file_read( struct fd *fd, struct async *async, int blocking, file_pos_t pos );
 static obj_handle_t device_file_write( struct fd *fd, struct async *async, int blocking, file_pos_t pos );
-static obj_handle_t device_file_flush( struct fd *fd, const async_data_t *async_data, int blocking );
+static obj_handle_t device_file_flush( struct fd *fd, struct async *async, int blocking );
 static obj_handle_t device_file_ioctl( struct fd *fd, ioctl_code_t code, struct async *async, int blocking );
 
 static const struct object_ops device_file_ops =
@@ -465,13 +465,13 @@ static void set_file_user_ptr( struct device_file *file, client_ptr_t ptr )
 
 /* queue an irp to the device */
 static obj_handle_t queue_irp( struct device_file *file, struct irp_call *irp,
-                               const async_data_t *async_data, int blocking )
+                               struct async *async, int blocking )
 {
     obj_handle_t handle = 0;
 
     if (blocking && !(handle = alloc_handle( current->process, irp, SYNCHRONIZE, 0 ))) return 0;
 
-    if (!(irp->async = fd_queue_async( file->fd, async_data, irp->iosb, ASYNC_TYPE_WAIT )))
+    if (!(irp->async = fd_queue_async( file->fd, async_get_data( async ), irp->iosb, ASYNC_TYPE_WAIT )))
     {
         if (handle) close_handle( current->process, handle );
         return 0;
@@ -505,7 +505,7 @@ static obj_handle_t device_file_read( struct fd *fd, struct async *async, int bl
     release_object( iosb );
     if (!irp) return 0;
 
-    handle = queue_irp( file, irp, async_get_data( async ), blocking );
+    handle = queue_irp( file, irp, async, blocking );
     release_object( irp );
     return handle;
 }
@@ -529,12 +529,12 @@ static obj_handle_t device_file_write( struct fd *fd, struct async *async, int b
     release_object( iosb );
     if (!irp) return 0;
 
-    handle = queue_irp( file, irp, async_get_data( async ), blocking );
+    handle = queue_irp( file, irp, async, blocking );
     release_object( irp );
     return handle;
 }
 
-static obj_handle_t device_file_flush( struct fd *fd, const async_data_t *async_data, int blocking )
+static obj_handle_t device_file_flush( struct fd *fd, struct async *async, int blocking )
 {
     struct device_file *file = get_fd_user( fd );
     struct irp_call *irp;
@@ -548,7 +548,7 @@ static obj_handle_t device_file_flush( struct fd *fd, const async_data_t *async_
     irp = create_irp( file, &params, NULL );
     if (!irp) return 0;
 
-    handle = queue_irp( file, irp, async_data, blocking );
+    handle = queue_irp( file, irp, async, blocking );
     release_object( irp );
     return handle;
 }
@@ -573,7 +573,7 @@ static obj_handle_t device_file_ioctl( struct fd *fd, ioctl_code_t code, struct
     release_object(iosb);
     if (!irp) return 0;
 
-    handle = queue_irp( file, irp, async_get_data( async ), blocking );
+    handle = queue_irp( file, irp, async, blocking );
     release_object( irp );
     return handle;
 }
diff --git a/server/fd.c b/server/fd.c
index d8ee68288de..2ed639f2d3e 100644
--- a/server/fd.c
+++ b/server/fd.c
@@ -2179,7 +2179,7 @@ obj_handle_t no_fd_write( struct fd *fd, struct async *async, int blocking, file
 }
 
 /* default flush() routine */
-obj_handle_t no_fd_flush( struct fd *fd, const async_data_t *async, int blocking )
+obj_handle_t no_fd_flush( struct fd *fd, struct async *async, int blocking )
 {
     set_error( STATUS_OBJECT_TYPE_MISMATCH );
     return 0;
@@ -2376,12 +2376,17 @@ void fd_copy_completion( struct fd *src, struct fd *dst )
 DECL_HANDLER(flush)
 {
     struct fd *fd = get_handle_fd_obj( current->process, req->async.handle, 0 );
+    struct async *async;
 
-    if (fd)
+    if (!fd) return;
+
+    async = create_async( current, &req->async, NULL );
+    if (async)
     {
-        reply->event = fd->fd_ops->flush( fd, &req->async, req->blocking );
-        release_object( fd );
+        reply->event = fd->fd_ops->flush( fd, async, req->blocking );
+        release_object( async );
     }
+    release_object( fd );
 }
 
 /* open a file object */
diff --git a/server/file.c b/server/file.c
index 2f5371dbb4e..85bd9501b58 100644
--- a/server/file.c
+++ b/server/file.c
@@ -74,7 +74,7 @@ static struct object *file_open_file( struct object *obj, unsigned int access,
 static void file_destroy( struct object *obj );
 
 static int file_get_poll_events( struct fd *fd );
-static obj_handle_t file_flush( struct fd *fd, const async_data_t *async, int blocking );
+static obj_handle_t file_flush( struct fd *fd, struct async *async, int blocking );
 static enum server_fd_type file_get_fd_type( struct fd *fd );
 
 static const struct object_ops file_ops =
@@ -295,7 +295,7 @@ static int file_get_poll_events( struct fd *fd )
     return events;
 }
 
-static obj_handle_t file_flush( struct fd *fd, const async_data_t *async, int blocking )
+static obj_handle_t file_flush( struct fd *fd, struct async *async, int blocking )
 {
     int unix_fd = get_unix_fd( fd );
     if (unix_fd != -1 && fsync( unix_fd ) == -1) file_set_error();
diff --git a/server/file.h b/server/file.h
index c3938c25f49..0a0e72f1e84 100644
--- a/server/file.h
+++ b/server/file.h
@@ -56,7 +56,7 @@ struct fd_ops
     /* perform a write on the file */
     obj_handle_t (*write)(struct fd *, struct async *, int, file_pos_t );
     /* flush the object buffers */
-    obj_handle_t (*flush)(struct fd *, const async_data_t *, int);
+    obj_handle_t (*flush)(struct fd *, struct async *, int);
     /* perform an ioctl on the file */
     obj_handle_t (*ioctl)(struct fd *fd, ioctl_code_t code, struct async *async, int blocking );
     /* queue an async operation */
@@ -102,7 +102,7 @@ extern void fd_async_wake_up( struct fd *fd, int type, unsigned int status );
 extern void fd_reselect_async( struct fd *fd, struct async_queue *queue );
 extern obj_handle_t no_fd_read( struct fd *fd, struct async *async, int blocking, file_pos_t pos );
 extern obj_handle_t no_fd_write( struct fd *fd, struct async *async, int blocking, file_pos_t pos );
-extern obj_handle_t no_fd_flush( struct fd *fd, const async_data_t *async, int blocking );
+extern obj_handle_t no_fd_flush( struct fd *fd, struct async *async, int blocking );
 extern obj_handle_t no_fd_ioctl( struct fd *fd, ioctl_code_t code, struct async *async, int blocking );
 extern obj_handle_t default_fd_ioctl( struct fd *fd, ioctl_code_t code, struct async *async, int blocking );
 extern void no_fd_queue_async( struct fd *fd, struct async *async, int type, int count );
diff --git a/server/named_pipe.c b/server/named_pipe.c
index 1668aafef66..1426023ad68 100644
--- a/server/named_pipe.c
+++ b/server/named_pipe.c
@@ -142,7 +142,7 @@ static const struct object_ops named_pipe_ops =
 static void pipe_server_dump( struct object *obj, int verbose );
 static struct fd *pipe_server_get_fd( struct object *obj );
 static void pipe_server_destroy( struct object *obj);
-static obj_handle_t pipe_server_flush( struct fd *fd, const async_data_t *async, int blocking );
+static obj_handle_t pipe_server_flush( struct fd *fd, struct async *async, int blocking );
 static enum server_fd_type pipe_server_get_fd_type( struct fd *fd );
 static obj_handle_t pipe_server_ioctl( struct fd *fd, ioctl_code_t code, struct async *async,
                                        int blocking );
@@ -187,7 +187,7 @@ static void pipe_client_dump( struct object *obj, int verbose );
 static int pipe_client_signaled( struct object *obj, struct wait_queue_entry *entry );
 static struct fd *pipe_client_get_fd( struct object *obj );
 static void pipe_client_destroy( struct object *obj );
-static obj_handle_t pipe_client_flush( struct fd *fd, const async_data_t *async, int blocking );
+static obj_handle_t pipe_client_flush( struct fd *fd, struct async *async, int blocking );
 static enum server_fd_type pipe_client_get_fd_type( struct fd *fd );
 
 static const struct object_ops pipe_client_ops =
@@ -545,17 +545,16 @@ static void check_flushed( void *arg )
     }
 }
 
-static obj_handle_t pipe_server_flush( struct fd *fd, const async_data_t *async_data, int blocking )
+static obj_handle_t pipe_server_flush( struct fd *fd, struct async *async, int blocking )
 {
     struct pipe_server *server = get_fd_user( fd );
     obj_handle_t handle = 0;
-    struct async *async;
 
     if (!server || server->state != ps_connected_server) return 0;
 
     if (!pipe_data_remaining( server )) return 0;
 
-    if ((async = fd_queue_async( server->fd, async_data, NULL, ASYNC_TYPE_WAIT )))
+    if ((async = fd_queue_async( server->fd, async_get_data( async ), NULL, ASYNC_TYPE_WAIT )))
     {
         /* there's no unix way to be alerted when a pipe becomes empty, so resort to polling */
         if (!server->flush_poll)
@@ -567,7 +566,7 @@ static obj_handle_t pipe_server_flush( struct fd *fd, const async_data_t *async_
     return handle;
 }
 
-static obj_handle_t pipe_client_flush( struct fd *fd, const async_data_t *async, int blocking )
+static obj_handle_t pipe_client_flush( struct fd *fd, struct async *async, int blocking )
 {
     /* FIXME: what do we have to do for this? */
     return 0;