refactor(block): block update methods return results

Now `update_rate_limiter` returns an error if
it is incorrectly called on the vhost-user-block.
Additionally error formatting has been updated to
use `Display`.

Signed-off-by: Egor Lazarchuk <[email protected]>

src/vmm/src/devices/virtio/block/device.rs

@@ -73,11 +73,9 @@ impl Block {
     }
 
     pub fn update_config(&mut self) -> Result<(), BlockError> {
-        match self.backend {
-            BlockBackend::Virtio(_) => Err(BlockError::InvalidBlockBackend),
-            BlockBackend::VhostUser(ref mut b) => {
-                b.config_update().map_err(BlockError::VhostUserBackend)
-            }
+        match self {
+            Self::Virtio(_) => Err(BlockError::InvalidBlockBackend),
+            Self::VhostUser(b) => b.config_update().map_err(BlockError::VhostUserBackend),
         }
     }
 

src/vmm/src/lib.rs

@@ -622,7 +622,7 @@ impl Vmm {
             .with_virtio_device_with_id(TYPE_BLOCK, drive_id, |block: &mut Block| {
                 block
                     .update_disk_image(path_on_host)
-                    .map_err(|err| format!("{:?}", err))
+                    .map_err(|err| err.to_string())
             })
             .map_err(VmmError::DeviceManager)
     }
@@ -647,7 +647,7 @@ impl Vmm {
     pub fn update_vhost_user_block_config(&mut self, drive_id: &str) -> Result<(), VmmError> {
         self.mmio_device_manager
             .with_virtio_device_with_id(TYPE_BLOCK, drive_id, |block: &mut Block| {
-                block.update_config().map_err(|err| format!("{:?}", err))
+                block.update_config().map_err(|err| err.to_string())
             })
             .map_err(VmmError::DeviceManager)
     }

tests/integration_tests/functional/test_api.py

@@ -804,20 +804,18 @@ def test_send_ctrl_alt_del(test_microvm_with_api):
 def _drive_patch(test_microvm):
     """Exercise drive patch test scenarios."""
     # Patches without mandatory fields for virtio block are not allowed.
-    expected_msg = "Invalid device type found on the MMIO bus. Please verify the request arguments."
+    expected_msg = "Unable to patch the block device: Device manager error: Running method expected different backend. Please verify the request arguments"
     with pytest.raises(RuntimeError, match=expected_msg):
         test_microvm.api.drive.patch(drive_id="scratch")
 
     # Patches with any fields for vhost-user block are not allowed.
-    expected_msg = "Invalid device type found on the MMIO bus. Please verify the request arguments."
     with pytest.raises(RuntimeError, match=expected_msg):
         test_microvm.api.drive.patch(
             drive_id="scratch_vub",
             path_on_host="some_path",
         )
 
     # Patches with any fields for vhost-user block are not allowed.
-    expected_msg = "Invalid device type found on the MMIO bus. Please verify the request arguments."
     with pytest.raises(RuntimeError, match=expected_msg):
         test_microvm.api.drive.patch(
             drive_id="scratch_vub",
@@ -848,10 +846,7 @@ def _drive_patch(test_microvm):
         )
 
     # Updates to `path_on_host` with an invalid path are not allowed.
-    expected_msg = (
-        "Unable to patch the block device: Device manager error: BackingFile(Os { code: 2, "
-        f'kind: NotFound, message: "No such file or directory" }}, "{drive_path}") Please verify the request arguments.'
-    )
+    expected_msg = f"Unable to patch the block device: Device manager error: Virtio backend error: Error manipulating the backing file: No such file or directory (os error 2) {drive_path} Please verify the request arguments"
     with pytest.raises(RuntimeError, match=re.escape(expected_msg)):
         test_microvm.api.drive.patch(drive_id="scratch", path_on_host=drive_path)