blockdev: Fail blockdev-add with encrypted images

Encrypted images need a password before they can be used, and we don't
want blockdev-add to create BDSes that aren't fully initialised. So for
now simply forbid encrypted images; we can come back to it later if we
need the functionality.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

blockdev.c

diff --git a/blockdev.c b/blockdev.c
index 357f760..561cb81 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2266,6 +2266,7 @@
 void qmp_blockdev_add(BlockdevOptions *options, Error **errp)
 {
     QmpOutputVisitor *ov = qmp_output_visitor_new();
+    DriveInfo *dinfo;
     QObject *obj;
     QDict *qdict;
     Error *local_err = NULL;
@@ -2301,12 +2302,18 @@
 
     qdict_flatten(qdict);
 
-    blockdev_init(NULL, qdict, &local_err);
+    dinfo = blockdev_init(NULL, qdict, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         goto fail;
     }
 
+    if (bdrv_key_required(dinfo->bdrv)) {
+        drive_uninit(dinfo);
+        error_setg(errp, "blockdev-add doesn't support encrypted devices");
+        goto fail;
+    }
+
 fail:
     qmp_output_visitor_cleanup(ov);
 }