block: Accept node-name for drive-mirror

In order to remove the necessity to use BlockBackend names in the
external API, we want to allow node-names everywhere. This converts
drive-mirror 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: Max Reitz <mreitz@redhat.com>

blockdev.c

@@ -3429,7 +3429,6 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
 void qmp_drive_mirror(DriveMirror *arg, Error **errp)
 {
     BlockDriverState *bs;
-    BlockBackend *blk;
     BlockDriverState *source, *target_bs;
     AioContext *aio_context;
     BlockMirrorBackingMode backing_mode;
@@ -3439,21 +3438,14 @@ void qmp_drive_mirror(DriveMirror *arg, Error **errp)
     int64_t size;
     const char *format = arg->format;
 
-    blk = blk_by_name(arg->device);
-    if (!blk) {
-        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
-                  "Device '%s' not found", arg->device);
+    bs = qmp_get_root_bs(arg->device, errp);
+    if (!bs) {
         return;
     }
 
-    aio_context = blk_get_aio_context(blk);
+    aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
-    if (!blk_is_available(blk)) {
-        error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, arg->device);
-        goto out;
-    }
-    bs = blk_bs(blk);
     if (!arg->has_mode) {
         arg->mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
     }

qapi/block-core.json

@@ -1128,7 +1128,7 @@
 # See DriveMirror for parameter descriptions
 #
 # Returns: nothing on success
-#          If @device is not a valid block device, DeviceNotFound
+#          If @device is not a valid block device, GenericError
 #
 # Since 1.3
 ##
@@ -1143,7 +1143,8 @@
 # @job-id: #optional identifier for the newly-created block job. If
 #          omitted, the device name will be used. (Since 2.7)
 #
-# @device:  the name of the device whose writes should be mirrored.
+# @device:  the device name or node-name of a root node whose writes should be
+#           mirrored.
 #
 # @target: the target of the new image. If the file exists, or if it
 #          is a device, the existing file/device will be used as the new

qmp-commands.hx

@@ -1689,7 +1689,8 @@ Arguments:
 
 - "job-id": Identifier for the newly-created block job. If omitted,
             the device name will be used. (json-string, optional)
-- "device": device name to operate on (json-string)
+- "device": the device name or node-name of a root node whose writes should be
+            mirrored. (json-string)
 - "target": name of new image file (json-string)
 - "format": format of new image (json-string, optional)
 - "node-name": the name of the new block driver state in the node graph

tests/qemu-iotests/041

@@ -38,7 +38,6 @@ class TestSingleDrive(iotests.QMPTestCase):
     image_len = 1 * 1024 * 1024 # MB
     qmp_cmd = 'drive-mirror'
     qmp_target = target_img
-    not_found_error = 'DeviceNotFound'
 
     def setUp(self):
         iotests.create_image(backing_img, self.image_len)
@@ -176,7 +175,7 @@ class TestSingleDrive(iotests.QMPTestCase):
 
         result = self.vm.qmp(self.qmp_cmd, device='ide1-cd0', sync='full',
                              target=self.qmp_target)
-        self.assert_qmp(result, 'error/class', self.not_found_error)
+        self.assert_qmp(result, 'error/class', 'GenericError')
 
     def test_image_not_found(self):
         result = self.vm.qmp(self.qmp_cmd, device='drive0', sync='full',
@@ -186,12 +185,11 @@ class TestSingleDrive(iotests.QMPTestCase):
     def test_device_not_found(self):
         result = self.vm.qmp(self.qmp_cmd, device='nonexistent', sync='full',
                              target=self.qmp_target)
-        self.assert_qmp(result, 'error/class', self.not_found_error)
+        self.assert_qmp(result, 'error/class', 'GenericError')
 
 class TestSingleBlockdev(TestSingleDrive):
     qmp_cmd = 'blockdev-mirror'
     qmp_target = 'node1'
-    not_found_error = 'GenericError'
 
     def setUp(self):
         TestSingleDrive.setUp(self)
@@ -922,7 +920,7 @@ class TestRepairQuorum(iotests.QMPTestCase):
                              node_name='repair0',
                              replaces='img1',
                              target=quorum_repair_img, format=iotests.imgfmt)
-        self.assert_qmp(result, 'error/class', 'DeviceNotFound')
+        self.assert_qmp(result, 'error/class', 'GenericError')
 
     def test_wrong_sync_mode(self):
         if not self.has_quorum():