chore(rustfs): adjudicate 37 bare dead_code allows in the four densest files

Continues backlog#1823 step 10 into the `rustfs` crate after #6161, #6162, #6173 and #6187 cleared the libraries. Each allow was stripped first and clippy asked which ones the compiler actually missed, so the verdicts rest on the diagnostic rather than on reading.

27 of the 37 were inert — including all eight in `admin/handlers/tier.rs` and seventeen of the nineteen in `storage/concurrency/io_schedule.rs`. Removing them changes no diagnostic.

Six items behind the remaining allows are deleted:

- `auth.rs`'s `determine_auth_type_and_version` and `is_request_presigned_signature_v4` are no-argument shims over their `_with_query` variants, which carry 2 and 5 live callers respectively. Neither shim had one.
- `io_schedule.rs`'s `lifetime_average_wait`, whose sibling accessors (`observation_count`, `average_wait`, `smoothed_load_level`) are all consumed.
- `console.rs`'s `version()`, `license()` and `doc()`. The live accessor is `version_info()`.

Two keep a reasoned allow. `io_schedule.rs`'s `original_priority` is written and never read back. And `console.rs`'s `config_handler`, with `Config::port` and `to_json()` which only it uses: that handler is covered by a test but no route registers it, so `/rustfs/console/api/v1/config` currently falls through to the SPA's static fallback. Deleting it would erase the only signal that the endpoint is meant to exist, so it stays annotated and the missing route is filed on the issue.

Refs backlog#1823

rustfs/src/admin/console.rs

@@ -119,6 +119,10 @@ async fn static_handler(uri: Uri) -> impl IntoResponse {
 #[derive(Debug, Serialize, Clone)]
 pub(crate) struct Config {
     #[serde(skip)]
+    #[allow(
+        dead_code,
+        reason = "reachable only from this file's tests: no route registers config_handler (backlog#1823)"
+    )]
     port: u16,
     api: Api,
     s3: S3,
@@ -176,11 +180,14 @@ impl Config {
         }
     }
 
+    #[allow(
+        dead_code,
+        reason = "reachable only from this file's tests: no route registers config_handler (backlog#1823)"
+    )]
     fn to_json(&self) -> String {
         serde_json::to_string(self).unwrap_or_default()
     }
 
-    #[allow(dead_code)]
     pub(crate) fn version_info(&self) -> String {
         format!(
             "RELEASE.{}@{} (rust {} {})",
@@ -190,21 +197,6 @@ impl Config {
             build::BUILD_TARGET
         )
     }
-
-    #[allow(dead_code)]
-    pub(crate) fn version(&self) -> String {
-        self.release.version.clone()
-    }
-
-    #[allow(dead_code)]
-    pub(crate) fn license(&self) -> String {
-        format!("{} {}", self.license.name.clone(), self.license.url.clone())
-    }
-
-    #[allow(dead_code)]
-    pub(crate) fn doc(&self) -> String {
-        self.doc.clone()
-    }
 }
 
 fn build_console_api_base_url(base_url: &str) -> String {
@@ -353,7 +345,10 @@ async fn version_handler() -> impl IntoResponse {
 /// - 200 OK with JSON body containing the console configuration if initialized.
 /// - 500 Internal Server Error if configuration is not initialized.
 #[instrument(fields(uri))]
-#[allow(dead_code)]
+#[allow(
+    dead_code,
+    reason = "reachable only from this file's tests: no route registers it (backlog#1823)"
+)]
 async fn config_handler(uri: Uri, headers: HeaderMap) -> impl IntoResponse {
     // Get the scheme from the headers or use the URI scheme
     let scheme = headers

rustfs/src/admin/handlers/tier.rs

@@ -53,25 +53,18 @@ const EVENT_ADMIN_TIER_STATE: &str = "admin_tier_state";
 #[derive(Debug, Clone, serde::Deserialize, Default)]
 pub struct AddTierQuery {
     #[serde(rename = "accessKey")]
-    #[allow(dead_code)]
     pub access_key: Option<String>,
-    #[allow(dead_code)]
     pub status: Option<String>,
     #[serde(rename = "secretKey")]
-    #[allow(dead_code)]
     pub secret_key: Option<String>,
     #[serde(rename = "serviceName")]
-    #[allow(dead_code)]
     pub service_name: Option<String>,
     #[serde(rename = "sessionToken")]
-    #[allow(dead_code)]
     pub session_token: Option<String>,
     pub tier: Option<String>,
     #[serde(rename = "tierName")]
-    #[allow(dead_code)]
     pub tier_name: Option<String>,
     #[serde(rename = "tierType")]
-    #[allow(dead_code)]
     pub tier_type: Option<String>,
     pub force: Option<String>,
 }
@@ -532,7 +525,6 @@ impl Operation for EditTier {
 #[derive(Debug, Clone, serde::Deserialize, Default)]
 pub struct BucketQuery {
     #[serde(rename = "bucket")]
-    #[allow(dead_code)]
     pub bucket: String,
 }
 pub struct ListTiers {}

rustfs/src/auth.rs

@@ -812,12 +812,10 @@ fn is_reserved_condition_key(key: &str, server_derived: &HashMap<String, Vec<Str
 /// # Returns
 /// * `AuthType` - The determined authentication type
 ///
-#[allow(dead_code)]
 pub fn get_request_auth_type(header: &HeaderMap) -> AuthType {
     get_request_auth_type_with_query(header, None)
 }
 
-#[allow(dead_code)]
 pub(crate) fn get_request_auth_type_with_query(header: &HeaderMap, query: Option<&str>) -> AuthType {
     if is_request_signature_v2(header) {
         AuthType::SignedV2
@@ -846,20 +844,6 @@ pub(crate) fn get_request_auth_type_with_query(header: &HeaderMap, query: Option
     }
 }
 
-/// Helper function to determine auth type and signature version
-///
-/// # Arguments
-/// * `header` - HTTP headers of the request
-///
-/// # Returns
-/// * `(String, String)` - Tuple of auth type and signature version
-///
-#[allow(dead_code)]
-fn determine_auth_type_and_version(header: &HeaderMap) -> (String, String) {
-    determine_auth_type_and_version_with_query(header, None)
-}
-
-#[allow(dead_code)]
 fn determine_auth_type_and_version_with_query(header: &HeaderMap, query: Option<&str>) -> (String, String) {
     match get_request_auth_type_with_query(header, query) {
         AuthType::JWT => ("JWT".to_string(), String::new()),
@@ -925,18 +909,6 @@ fn is_request_signature_v2(header: &HeaderMap) -> bool {
     false
 }
 
-/// Verify if request has AWS PreSign Version '4'
-///
-/// # Arguments
-/// * `header` - HTTP headers of the request
-///
-/// # Returns
-/// * `bool` - True if request has AWS PreSign Version '4', false otherwise
-#[allow(dead_code)]
-pub(crate) fn is_request_presigned_signature_v4(header: &HeaderMap) -> bool {
-    is_request_presigned_signature_v4_with_query(header, None)
-}
-
 pub(crate) fn is_request_presigned_signature_v4_with_query(header: &HeaderMap, query: Option<&str>) -> bool {
     if let Some(credential) = header.get(AMZ_CREDENTIAL) {
         return !credential.to_str().unwrap_or("").is_empty();

rustfs/src/storage/concurrency/io_schedule.rs

@@ -72,7 +72,6 @@ impl IoLoadLevel {
     }
 
     /// Get the load level as a string for metrics labels.
-    #[allow(dead_code)]
     pub fn as_str(&self) -> &'static str {
         match self {
             IoLoadLevel::Low => "low",
@@ -83,7 +82,6 @@ impl IoLoadLevel {
     }
 
     /// Get the load level as a numeric index (0=Low, 1=Medium, 2=High, 3=Critical).
-    #[allow(dead_code)]
     pub fn level_index(&self) -> u8 {
         match self {
             IoLoadLevel::Low => 0,
@@ -118,7 +116,6 @@ pub enum IoPriority {
 
 impl IoPriority {
     /// Determine priority from request size using scheduler config thresholds.
-    #[allow(dead_code)]
     pub fn from_size(size: i64) -> Self {
         Self::from_size_with_thresholds(
             size,
@@ -152,19 +149,16 @@ impl IoPriority {
     }
 
     /// Check if this is high priority.
-    #[allow(dead_code)]
     pub fn is_high(&self) -> bool {
         matches!(self, IoPriority::High)
     }
 
     /// Check if this is normal priority.
-    #[allow(dead_code)]
     pub fn is_normal(&self) -> bool {
         matches!(self, IoPriority::Normal)
     }
 
     /// Check if this is low priority.
-    #[allow(dead_code)]
     pub fn is_low(&self) -> bool {
         matches!(self, IoPriority::Low)
     }
@@ -403,7 +397,6 @@ impl IoSchedulerConfig {
 
 /// I/O queue status for monitoring.
 #[derive(Debug, Clone, Default)]
-#[allow(dead_code)]
 pub struct IoQueueStatus {
     /// Total permits available.
     pub total_permits: usize,
@@ -520,7 +513,6 @@ pub struct IoStrategyCore {
 
 impl IoStrategyCore {
     /// Create a minimal IoStrategyCore with essential fields only.
-    #[allow(dead_code)]
     pub fn new(storage_media: StorageMedia, access_pattern: AccessPattern, buffer_size: usize) -> Self {
         Self {
             storage_media,
@@ -1194,7 +1186,6 @@ impl IoStrategy {
     }
 
     /// Get a human-readable description of the current I/O strategy.
-    #[allow(dead_code)]
     pub fn description(&self) -> String {
         format!(
             "IoStrategy[{:?}]: buffer={}KB, multiplier={:.2}, readahead={}, wait={:?}",
@@ -1282,14 +1273,6 @@ impl IoLoadMetrics {
         IoLoadLevel::from_wait_duration(self.average_wait())
     }
 
-    /// Get the overall average wait since startup
-    #[allow(dead_code)]
-    pub(crate) fn lifetime_average_wait(&self) -> Duration {
-        let total = self.total_wait_ns.load(Ordering::Relaxed);
-        let count = self.observation_count.load(Ordering::Relaxed);
-        total.checked_div(count).map(Duration::from_nanos).unwrap_or(Duration::ZERO)
-    }
-
     /// Get the total observation count
     pub(crate) fn observation_count(&self) -> u64 {
         self.observation_count.load(Ordering::Relaxed)
@@ -1450,13 +1433,13 @@ use tracing::warn;
 
 /// Queued I/O request with metadata.
 #[derive(Debug)]
-#[allow(dead_code)]
 struct QueuedRequest<T> {
     /// The actual request payload.
     request: T,
     /// Time when the request was enqueued.
     enqueue_time: Instant,
     /// Original priority assigned to the request.
+    #[allow(dead_code, reason = "written but never read back (backlog#1823)")]
     original_priority: IoPriority,
     /// Current priority (may be boosted for starvation prevention).
     current_priority: IoPriority,
@@ -1466,7 +1449,6 @@ struct QueuedRequest<T> {
 
 /// Queue statistics for monitoring.
 #[derive(Debug, Clone, Default)]
-#[allow(dead_code)]
 struct QueueStats {
     /// Number of high priority requests processed.
     high_processed: u64,
@@ -1552,7 +1534,6 @@ impl Default for IoPriorityQueueConfig {
 
 impl IoPriorityQueueConfig {
     /// Load configuration from environment.
-    #[allow(dead_code)]
     pub fn from_env() -> Self {
         Self {
             queue_high_capacity: rustfs_utils::get_env_usize(
@@ -1603,7 +1584,6 @@ impl IoPriorityQueueConfig {
 
 impl<T> IoPriorityQueue<T> {
     /// Create a new priority queue with the given configuration.
-    #[allow(dead_code)]
     pub fn new(config: IoPriorityQueueConfig) -> Self {
         let config_clone = config.clone();
         Self {
@@ -1617,7 +1597,6 @@ impl<T> IoPriorityQueue<T> {
     }
 
     /// Enqueue a request with the given priority.
-    #[allow(dead_code)]
     pub async fn enqueue(&self, priority: IoPriority, request: T) {
         let queued = QueuedRequest {
             request,
@@ -1638,7 +1617,6 @@ impl<T> IoPriorityQueue<T> {
     ///
     /// This method performs starvation prevention checks before dequeuing.
     /// Returns `None` if all queues are empty.
-    #[allow(dead_code)]
     pub async fn dequeue(&self) -> Option<(T, IoPriority)> {
         // 1. Check for starvation prevention
         self.check_starvation().await;
@@ -1716,7 +1694,6 @@ impl<T> IoPriorityQueue<T> {
     }
 
     /// Get current queue status for monitoring.
-    #[allow(dead_code)]
     pub async fn status(&self) -> IoQueueStatus {
         let high_queue = self.high_queue.lock().await;
         let normal_queue = self.normal_queue.lock().await;
@@ -1737,7 +1714,6 @@ impl<T> IoPriorityQueue<T> {
     }
 
     /// Get the total number of queued requests.
-    #[allow(dead_code)]
     pub async fn len(&self) -> usize {
         let high_queue = self.high_queue.lock().await;
         let normal_queue = self.normal_queue.lock().await;
@@ -1747,7 +1723,6 @@ impl<T> IoPriorityQueue<T> {
     }
 
     /// Check if all queues are empty.
-    #[allow(dead_code)]
     pub async fn is_empty(&self) -> bool {
         self.len().await == 0
     }