block/export: Move refcount from NBDExport to BlockExport

Having a refcount makes sense for all types of block exports. It is also
a prerequisite for keeping a list of all exports at the BlockExport
level.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-14-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/block/export/export.c b/block/export/export.c
index 05bc5e3744..baba4e94ff 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -49,6 +49,20 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
     return drv->create(export, errp);
 }
 
+void blk_exp_ref(BlockExport *exp)
+{
+    assert(exp->refcount > 0);
+    exp->refcount++;
+}
+
+void blk_exp_unref(BlockExport *exp)
+{
+    assert(exp->refcount > 0);
+    if (--exp->refcount == 0) {
+        exp->drv->delete(exp);
+    }
+}
+
 void qmp_block_export_add(BlockExportOptions *export, Error **errp)
 {
     blk_exp_add(export, errp);