block: Accept node-name for blockdev-snapshot-delete-internal-sync

In order to remove the necessity to use BlockBackend names in the
external API, we want to allow node-names everywhere. This converts
blockdev-snapshot-delete-internal-sync to accept a node-name without
lifting the restriction that we're operating at a root node.

In case of an invalid device name, the command returns the GenericError
error class now instead of DeviceNotFound, because this is what
qmp_get_root_bs() returns.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

blockdev.c

@@ -1306,21 +1306,17 @@ SnapshotInfo *qmp_blockdev_snapshot_delete_internal_sync(const char *device,
                                                          Error **errp)
 {
     BlockDriverState *bs;
-    BlockBackend *blk;
     AioContext *aio_context;
     QEMUSnapshotInfo sn;
     Error *local_err = NULL;
     SnapshotInfo *info = NULL;
     int ret;
 
-    blk = blk_by_name(device);
-    if (!blk) {
-        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
-                  "Device '%s' not found", device);
+    bs = qmp_get_root_bs(device, errp);
+    if (!bs) {
         return NULL;
     }
-
-    aio_context = blk_get_aio_context(blk);
+    aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
     if (!has_id) {
@@ -1336,12 +1332,6 @@ SnapshotInfo *qmp_blockdev_snapshot_delete_internal_sync(const char *device,
         goto out_aio_context;
     }
 
-    if (!blk_is_available(blk)) {
-        error_setg(errp, "Device '%s' has no medium", device);
-        goto out_aio_context;
-    }
-    bs = blk_bs(blk);
-
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE, errp)) {
         goto out_aio_context;
     }

qapi/block.json

@@ -99,14 +99,15 @@
 # both. One of the name or id is required. Return SnapshotInfo for the
 # successfully deleted snapshot.
 #
-# @device: the name of the device to delete the snapshot from
+# @device: the device name or node-name of a root node to delete the snapshot
+#          from
 #
 # @id: optional the snapshot's ID to be deleted
 #
 # @name: optional the snapshot's name to be deleted
 #
 # Returns: SnapshotInfo on success
-#          If @device is not a valid block device, DeviceNotFound
+#          If @device is not a valid block device, GenericError
 #          If snapshot not found, GenericError
 #          If the format of the image used does not support it,
 #          BlockFormatFeatureNotSupported

qmp-commands.hx

@@ -1639,7 +1639,7 @@ fail.
 
 Arguments:
 
-- "device": device name (json-string)
+- "device": the device name or node-name of a root node (json-string)
 - "id": ID of the snapshot (json-string, optional)
 - "name": name of the snapshot (json-string, optional)
 

tests/qemu-iotests/057

@@ -239,7 +239,7 @@ class TestSnapshotDelete(ImageSnapshotTestCase):
         result = self.vm.qmp('blockdev-snapshot-delete-internal-sync',
                               device = 'drive_error',
                               id = '0')
-        self.assert_qmp(result, 'error/class', 'DeviceNotFound')
+        self.assert_qmp(result, 'error/class', 'GenericError')
 
     def test_error_no_id_and_name(self):
         result = self.vm.qmp('blockdev-snapshot-delete-internal-sync',