Fix clippy warnings

src/block.rs

@@ -16,13 +16,14 @@ impl BlockDevice {
             .file_name()
             .and_then(|s| s.to_str())
             .map(String::from)
-            .ok_or(Error::from(ErrorKind::InvalidDeviceName))?;
+            .ok_or_else(|| Error::from(ErrorKind::InvalidDeviceName))?;
 
         debug!(
             "path: {:?}, real path: {:?}, device name: {:?}",
             path, real_path, device_name
         );
 
+        drop(path);
         let _self = Self { name: device_name };
         if !(_self.is_removable()? || _self.is_loop_device()) {
             return Err(ErrorKind::DangerousDevice)?;

src/error.rs

@@ -95,6 +95,6 @@ impl From<ErrorKind> for Error {
 
 impl From<Context<ErrorKind>> for Error {
     fn from(inner: Context<ErrorKind>) -> Error {
-        Error { inner: inner }
+        Error { inner }
     }
 }

src/mountstack.rs

@@ -6,14 +6,14 @@ use nix::mount::{mount, umount, MsFlags};
 use std::borrow::Cow;
 use std::path::Path;
 
-#[derive(Debug)]
+#[derive(Debug, Clone, Copy)]
 pub enum Filesystem {
     Ext4,
     Vfat,
 }
 
 impl Filesystem {
-    fn to_type(&self) -> &'static str {
+    fn to_type(self) -> &'static str {
         match self {
             Filesystem::Ext4 => "ext4",
             Filesystem::Vfat => "vfat",