virtio-blk: Functions for op blocker management

Put the code for setting up and removing op blockers into an own
function, respectively. Then, we can invoke those functions whenever a
BDS is removed from an virtio-blk BB or inserted into it.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

hw/block/dataplane/virtio-blk.c

@@ -40,6 +40,8 @@ struct VirtIOBlockDataPlane {
     EventNotifier *guest_notifier;  /* irq */
     QEMUBH *bh;                     /* bh for guest notification */
 
+    Notifier insert_notifier, remove_notifier;
+
     /* Note that these EventNotifiers are assigned by value.  This is
      * fine as long as you do not call event_notifier_cleanup on them
      * (because you don't own the file descriptor or handle; you just
@@ -137,6 +139,54 @@ static void handle_notify(EventNotifier *e)
     blk_io_unplug(s->conf->conf.blk);
 }
 
+static void data_plane_set_up_op_blockers(VirtIOBlockDataPlane *s)
+{
+    assert(!s->blocker);
+    error_setg(&s->blocker, "block device is in use by data plane");
+    blk_op_block_all(s->conf->conf.blk, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_RESIZE, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_DRIVE_DEL, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_BACKUP_SOURCE, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_CHANGE, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_COMMIT_SOURCE, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_COMMIT_TARGET, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_EJECT, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT,
+                   s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT,
+                   s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE,
+                   s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_MIRROR_SOURCE, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_STREAM, s->blocker);
+    blk_op_unblock(s->conf->conf.blk, BLOCK_OP_TYPE_REPLACE, s->blocker);
+}
+
+static void data_plane_remove_op_blockers(VirtIOBlockDataPlane *s)
+{
+    if (s->blocker) {
+        blk_op_unblock_all(s->conf->conf.blk, s->blocker);
+        error_free(s->blocker);
+        s->blocker = NULL;
+    }
+}
+
+static void data_plane_blk_insert_notifier(Notifier *n, void *data)
+{
+    VirtIOBlockDataPlane *s = container_of(n, VirtIOBlockDataPlane,
+                                           insert_notifier);
+    assert(s->conf->conf.blk == data);
+    data_plane_set_up_op_blockers(s);
+}
+
+static void data_plane_blk_remove_notifier(Notifier *n, void *data)
+{
+    VirtIOBlockDataPlane *s = container_of(n, VirtIOBlockDataPlane,
+                                           remove_notifier);
+    assert(s->conf->conf.blk == data);
+    data_plane_remove_op_blockers(s);
+}
+
 /* Context: QEMU global mutex held */
 void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
                                   VirtIOBlockDataPlane **dataplane,
@@ -179,22 +229,12 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
     s->ctx = iothread_get_aio_context(s->iothread);
     s->bh = aio_bh_new(s->ctx, notify_guest_bh, s);
 
-    error_setg(&s->blocker, "block device is in use by data plane");
-    blk_op_block_all(conf->conf.blk, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_RESIZE, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_DRIVE_DEL, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_BACKUP_SOURCE, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_CHANGE, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_COMMIT_SOURCE, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_COMMIT_TARGET, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_EJECT, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE,
-                   s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_MIRROR_SOURCE, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_STREAM, s->blocker);
-    blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_REPLACE, s->blocker);
+    s->insert_notifier.notify = data_plane_blk_insert_notifier;
+    s->remove_notifier.notify = data_plane_blk_remove_notifier;
+    blk_add_insert_bs_notifier(conf->conf.blk, &s->insert_notifier);
+    blk_add_remove_bs_notifier(conf->conf.blk, &s->remove_notifier);
+
+    data_plane_set_up_op_blockers(s);
 
     *dataplane = s;
 }
@@ -207,8 +247,9 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
     }
 
     virtio_blk_data_plane_stop(s);
-    blk_op_unblock_all(s->conf->conf.blk, s->blocker);
-    error_free(s->blocker);
+    data_plane_remove_op_blockers(s);
+    notifier_remove(&s->insert_notifier);
+    notifier_remove(&s->remove_notifier);
     qemu_bh_delete(s->bh);
     object_unref(OBJECT(s->iothread));
     g_free(s);