virtio-blk-dataplane: Improve error reporting

Return an Error so that it can be propagated later.
Tested-by: NStefan Hajnoczi <stefanha@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
[AF: Rebased]
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/block/dataplane/virtio-blk.c

@@ -380,8 +380,9 @@ static void start_data_plane_bh(void *opaque)
                        s, QEMU_THREAD_JOINABLE);
 }
 
-bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
-                                  VirtIOBlockDataPlane **dataplane)
+void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
+                                  VirtIOBlockDataPlane **dataplane,
+                                  Error **errp)
 {
     VirtIOBlockDataPlane *s;
     int fd;
@@ -389,33 +390,35 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
     *dataplane = NULL;
 
     if (!blk->data_plane) {
-        return true;
+        return;
     }
 
     if (blk->scsi) {
-        error_report("device is incompatible with x-data-plane, use scsi=off");
-        return false;
+        error_setg(errp,
+                   "device is incompatible with x-data-plane, use scsi=off");
+        return;
     }
 
     if (blk->config_wce) {
-        error_report("device is incompatible with x-data-plane, "
-                     "use config-wce=off");
-        return false;
+        error_setg(errp, "device is incompatible with x-data-plane, "
+                         "use config-wce=off");
+        return;
     }
 
     /* If dataplane is (re-)enabled while the guest is running there could be
      * block jobs that can conflict.
      */
     if (bdrv_in_use(blk->conf.bs)) {
-        error_report("cannot start dataplane thread while device is in use");
-        return false;
+        error_setg(errp,
+                   "cannot start dataplane thread while device is in use");
+        return;
     }
 
     fd = raw_get_aio_fd(blk->conf.bs);
     if (fd < 0) {
-        error_report("drive is incompatible with x-data-plane, "
-                     "use format=raw,cache=none,aio=native");
-        return false;
+        error_setg(errp, "drive is incompatible with x-data-plane, "
+                         "use format=raw,cache=none,aio=native");
+        return;
     }
 
     s = g_new0(VirtIOBlockDataPlane, 1);
@@ -427,7 +430,6 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
     bdrv_set_in_use(blk->conf.bs, 1);
 
     *dataplane = s;
-    return true;
 }
 
 void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)

hw/block/dataplane/virtio-blk.h

@@ -19,8 +19,9 @@
 
 typedef struct VirtIOBlockDataPlane VirtIOBlockDataPlane;
 
-bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
-                                  VirtIOBlockDataPlane **dataplane);
+void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
+                                  VirtIOBlockDataPlane **dataplane,
+                                  Error **errp);
 void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s);
 void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s);
 void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s);

hw/block/virtio-blk.c

@@ -657,6 +657,7 @@ static void virtio_blk_migration_state_changed(Notifier *notifier, void *data)
     VirtIOBlock *s = container_of(notifier, VirtIOBlock,
                                   migration_state_notifier);
     MigrationState *mig = data;
+    Error *err = NULL;
 
     if (migration_in_setup(mig)) {
         if (!s->dataplane) {
@@ -671,7 +672,11 @@ static void virtio_blk_migration_state_changed(Notifier *notifier, void *data)
         }
         bdrv_drain_all(); /* complete in-flight non-dataplane requests */
         virtio_blk_data_plane_create(VIRTIO_DEVICE(s), &s->blk,
-                                     &s->dataplane);
+                                     &s->dataplane, &err);
+        if (err != NULL) {
+            error_report("%s", error_get_pretty(err));
+            error_free(err);
+        }
     }
 }
 #endif /* CONFIG_VIRTIO_BLK_DATA_PLANE */
@@ -681,6 +686,9 @@ static int virtio_blk_device_init(VirtIODevice *vdev)
     DeviceState *qdev = DEVICE(vdev);
     VirtIOBlock *s = VIRTIO_BLK(vdev);
     VirtIOBlkConf *blk = &(s->blk);
+#ifdef CONFIG_VIRTIO_BLK_DATA_PLANE
+    Error *err = NULL;
+#endif
     static int virtio_blk_id;
 
     if (!blk->conf.bs) {
@@ -708,7 +716,10 @@ static int virtio_blk_device_init(VirtIODevice *vdev)
 
     s->vq = virtio_add_queue(vdev, 128, virtio_blk_handle_output);
 #ifdef CONFIG_VIRTIO_BLK_DATA_PLANE
-    if (!virtio_blk_data_plane_create(vdev, blk, &s->dataplane)) {
+    virtio_blk_data_plane_create(vdev, blk, &s->dataplane, &err);
+    if (err != NULL) {
+        error_report("%s", error_get_pretty(err));
+        error_free(err);
         virtio_cleanup(vdev);
         return -1;
     }