migration: improve error reporting of block driver state name

With blockdev, a BlockDriverState may not have a device name,
so using a node name is required as an alternative.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200827111606.1408275-2-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

migration/savevm.c

@@ -2682,7 +2682,7 @@ int save_snapshot(const char *name, Error **errp)
 
     if (!bdrv_all_can_snapshot(&bs)) {
         error_setg(errp, "Device '%s' is writable but does not support "
-                   "snapshots", bdrv_get_device_name(bs));
+                   "snapshots", bdrv_get_device_or_node_name(bs));
         return ret;
     }
 
@@ -2691,7 +2691,7 @@ int save_snapshot(const char *name, Error **errp)
         ret = bdrv_all_delete_snapshot(name, &bs1, errp);
         if (ret < 0) {
             error_prepend(errp, "Error while deleting snapshot on device "
-                          "'%s': ", bdrv_get_device_name(bs1));
+                          "'%s': ", bdrv_get_device_or_node_name(bs1));
             return ret;
         }
     }
@@ -2766,7 +2766,7 @@ int save_snapshot(const char *name, Error **errp)
     ret = bdrv_all_create_snapshot(sn, bs, vm_state_size, &bs);
     if (ret < 0) {
         error_setg(errp, "Error while creating snapshot on '%s'",
-                   bdrv_get_device_name(bs));
+                   bdrv_get_device_or_node_name(bs));
         goto the_end;
     }
 
@@ -2884,14 +2884,14 @@ int load_snapshot(const char *name, Error **errp)
     if (!bdrv_all_can_snapshot(&bs)) {
         error_setg(errp,
                    "Device '%s' is writable but does not support snapshots",
-                   bdrv_get_device_name(bs));
+                   bdrv_get_device_or_node_name(bs));
         return -ENOTSUP;
     }
     ret = bdrv_all_find_snapshot(name, &bs);
     if (ret < 0) {
         error_setg(errp,
                    "Device '%s' does not have the requested snapshot '%s'",
-                   bdrv_get_device_name(bs), name);
+                   bdrv_get_device_or_node_name(bs), name);
         return ret;
     }
 
@@ -2920,7 +2920,7 @@ int load_snapshot(const char *name, Error **errp)
     ret = bdrv_all_goto_snapshot(name, &bs, errp);
     if (ret < 0) {
         error_prepend(errp, "Could not load snapshot '%s' on '%s': ",
-                      name, bdrv_get_device_name(bs));
+                      name, bdrv_get_device_or_node_name(bs));
         goto err_drain;
     }
 

tests/qemu-iotests/267.out

@@ -81,11 +81,11 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
 Testing: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=file
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) savevm snap0
-Error: Device '' is writable but does not support snapshots
+Error: Device 'file' is writable but does not support snapshots
 (qemu) info snapshots
 No available block device supports snapshots
 (qemu) loadvm snap0
-Error: Device '' is writable but does not support snapshots
+Error: Device 'file' is writable but does not support snapshots
 (qemu) quit
 
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728