block: add bdrv_get_device_or_node_name()

This function gets the device name associated with a BlockDriverState,
or its node name if the device name is empty.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 4fa30aa8d61d9052ce266fd5429a59a14e941255.1428485266.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/block.c b/block.c
index d13b2e7835..cc8010ee20 100644
--- a/block.c
+++ b/block.c
@@ -3980,6 +3980,15 @@ const char *bdrv_get_device_name(const BlockDriverState *bs)
     return bs->blk ? blk_name(bs->blk) : "";
 }
 
+/* This can be used to identify nodes that might not have a device
+ * name associated. Since node and device names live in the same
+ * namespace, the result is unambiguous. The exception is if both are
+ * absent, then this returns an empty (non-null) string. */
+const char *bdrv_get_device_or_node_name(const BlockDriverState *bs)
+{
+    return bs->blk ? blk_name(bs->blk) : bs->node_name;
+}
+
 int bdrv_get_flags(BlockDriverState *bs)
 {
     return bs->open_flags;