refactor(balloon): remove unused error variants

Remove some error variants that were not used in the code.

Signed-off-by: Riccardo Mancini <[email protected]>

Author: Manciukic

src/vmm/src/devices/virtio/balloon/mod.rs

@@ -67,8 +67,6 @@ const VIRTIO_BALLOON_S_HTLB_PGFAIL: u16 = 9;
 /// Balloon device related errors.
 #[derive(Debug, thiserror::Error, displaydoc::Display)]
 pub enum BalloonError {
-    /// No balloon device found.
-    DeviceNotFound,
     /// Device not activated yet.
     DeviceNotActive,
     /// EventFd error: {0}

src/vmm/src/vmm_config/balloon.rs

@@ -16,18 +16,10 @@ type MutexBalloon = Arc<Mutex<Balloon>>;
 pub enum BalloonConfigError {
     /// No balloon device found.
     DeviceNotFound,
-    /// Device is inactive, check if balloon driver is enabled in guest kernel.
-    DeviceNotActive,
-    /// Cannot enable/disable the statistics after boot.
-    InvalidStatsUpdate,
     /// Amount of pages requested is too large.
     TooManyPagesRequested,
-    /// Statistics for the balloon device are not enabled
-    StatsNotFound,
     /// Error creating the balloon device: {0}
     CreateFailure(crate::devices::virtio::balloon::BalloonError),
-    /// Error updating the balloon device configuration: {0}
-    UpdateFailure(std::io::Error),
     /// Firecracker's huge pages support is incompatible with memory ballooning.
     HugePages,
 }