tree-wide: cleanup manual map/flatten

found with clippy, best viewed with `-w` ;)

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

src/api2/backup/environment.rs

@@ -246,10 +246,7 @@ impl BackupEnvironment {
     pub fn lookup_chunk(&self, digest: &[u8; 32]) -> Option<u32> {
         let state = self.state.lock().unwrap();
 
-        match state.known_chunks.get(digest) {
-            Some(len) => Some(*len),
-            None => None,
-        }
+        state.known_chunks.get(digest).map(|len| *len)
     }
 
     /// Store the writer with an unique ID

src/api2/node/syslog.rs

@@ -134,11 +134,7 @@ fn get_syslog(
     mut rpcenv: &mut dyn RpcEnvironment,
 ) -> Result<Value, Error> {
 
-    let service = if let Some(service) = param["service"].as_str() {
-        Some(crate::api2::node::services::real_service_name(service))
-    } else {
-        None
-    };
+    let service = param["service"].as_str().map(|service| crate::api2::node::services::real_service_name(service));
 
     let (count, lines) = dump_journal(
         param["start"].as_u64(),

src/tools/disks/mod.rs

@@ -982,21 +982,14 @@ pub fn create_file_system(disk: &Disk, fs_type: FileSystemType) -> Result<(), Er
 
 /// Block device name completion helper
 pub fn complete_disk_name(_arg: &str, _param: &HashMap<String, String>) -> Vec<String> {
-    let mut list = Vec::new();
-
     let dir = match proxmox_sys::fs::scan_subdir(libc::AT_FDCWD, "/sys/block", &BLOCKDEVICE_NAME_REGEX) {
         Ok(dir) => dir,
-        Err(_) => return list,
+        Err(_) => return vec![],
     };
 
-    for item in dir {
-        if let Ok(item) = item {
-            let name = item.file_name().to_str().unwrap().to_string();
-            list.push(name);
-        }
-    }
-
-    list
+    dir.flatten().map(|item| {
+        item.file_name().to_str().unwrap().to_string()
+    }).collect()
 }
 
 /// Read the FS UUID (parse blkid output)