block: Add bdrv_get_node_name

This returns the node name of a BDS. Remove the TODO comment and expect
the callers to be explicit.
Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block.c

@@ -3817,6 +3817,11 @@ BlockDriverState *bdrv_next(BlockDriverState *bs)
     return QTAILQ_NEXT(bs, device_list);
 }
 
+const char *bdrv_get_node_name(const BlockDriverState *bs)
+{
+    return bs->node_name;
+}
+
 /* TODO check what callers really want: bs->node_name or blk_name() */
 const char *bdrv_get_device_name(const BlockDriverState *bs)
 {

include/block/block.h

@@ -382,6 +382,7 @@ int bdrv_set_key(BlockDriverState *bs, const char *key);
 int bdrv_query_missing_keys(void);
 void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
                          void *opaque);
+const char *bdrv_get_node_name(const BlockDriverState *bs);
 const char *bdrv_get_device_name(const BlockDriverState *bs);
 int bdrv_get_flags(BlockDriverState *bs);
 int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num,