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>

2 files changed, 15 insertions, 2 deletions

diff --git a/include/block/export.h b/include/block/export.h
index e7af2c7687..5236a35e12 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -24,12 +24,27 @@ typedef struct BlockExportDriver {
 
     /* Creates and starts a new block export */
     BlockExport *(*create)(BlockExportOptions *, Error **);
+
+    /*
+     * Frees a removed block export. This function is only called after all
+     * references have been dropped.
+     */
+    void (*delete)(BlockExport *);
 } BlockExportDriver;
 
 struct BlockExport {
     const BlockExportDriver *drv;
+
+    /*
+     * Reference count for this block export. This includes strong references
+     * both from the owner (qemu-nbd or the monitor) and clients connected to
+     * the export.
+     */
+    int refcount;
 };
 
 BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
+void blk_exp_ref(BlockExport *exp);
+void blk_exp_unref(BlockExport *exp);
 
 #endif
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 1dafe70615..e3bd112227 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -338,8 +338,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
 void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
 void nbd_export_close(NBDExport *exp);
 void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
-void nbd_export_get(NBDExport *exp);
-void nbd_export_put(NBDExport *exp);
 
 AioContext *nbd_export_aio_context(NBDExport *exp);
 NBDExport *nbd_export_find(const char *name);