fix(scanner): cancel scan workers with cycle scope

crates/scanner/src/scanner_budget.rs

@@ -255,7 +255,7 @@ impl ScannerCycleBudget {
             }
             if self
                 .max_directories
-                .is_some_and(|max_directories| directories > max_directories)
+                .is_some_and(|max_directories| directory_budget_exhausted(directories, max_directories))
             {
                 self.cancel_for(ScannerCycleBudgetReason::Directories);
             }
@@ -281,7 +281,7 @@ impl ScannerCycleBudget {
         }
         if self
             .max_directories
-            .is_some_and(|max_directories| directories > max_directories)
+            .is_some_and(|max_directories| directory_budget_exhausted(directories, max_directories))
         {
             self.cancel_for(ScannerCycleBudgetReason::Directories);
             return false;
@@ -329,6 +329,13 @@ fn saturating_fetch_add(value: &AtomicU64, delta: u64) -> u64 {
     }
 }
 
+fn directory_budget_exhausted(directories: u64, max_directories: u64) -> bool {
+    // Saturation hides a remote max+1 update when the configured limit is the
+    // largest representable counter. Treat that boundary as exhausted rather
+    // than allowing work to continue indefinitely.
+    directories > max_directories || (directories == u64::MAX && max_directories == u64::MAX)
+}
+
 impl Drop for ScannerCycleBudget {
     fn drop(&mut self) {
         self.token.cancel();
@@ -471,6 +478,35 @@ mod tests {
         assert_eq!(directory_budget.reason(), Some(ScannerCycleBudgetReason::Directories));
     }
 
+    #[test]
+    fn directory_budget_fails_closed_when_progress_saturates() {
+        let parent = CancellationToken::new();
+        let budget = ScannerCycleBudget::new(
+            &parent,
+            ScannerCycleBudgetConfig {
+                max_directories: Some(u64::MAX),
+                ..Default::default()
+            },
+        );
+
+        budget.record_remote_progress(0, u64::MAX);
+
+        assert_eq!(budget.reason(), Some(ScannerCycleBudgetReason::Directories));
+        assert!(budget.token().is_cancelled());
+
+        let local_budget = ScannerCycleBudget::new(
+            &parent,
+            ScannerCycleBudgetConfig {
+                max_directories: Some(u64::MAX),
+                ..Default::default()
+            },
+        );
+        local_budget.record_remote_progress(0, u64::MAX - 1);
+        assert!(!local_budget.budget_elapsed());
+        assert!(!local_budget.try_start_directory());
+        assert_eq!(local_budget.reason(), Some(ScannerCycleBudgetReason::Directories));
+    }
+
     #[test]
     fn explicit_progress_tracking_counts_unbounded_remote_work_without_cancelling() {
         let parent = CancellationToken::new();

crates/scanner/src/scanner_io.rs

@@ -48,6 +48,7 @@ use time::OffsetDateTime;
 use tokio::sync::{Mutex, Notify, Semaphore, mpsc};
 use tokio::time::Duration;
 use tokio_util::sync::CancellationToken;
+use tokio_util::task::AbortOnDropHandle;
 use tracing::{debug, error, warn};
 
 use crate::ScannerObjectInfo as ObjectInfo;

crates/scanner/src/scanner_io/io_cache.rs

@@ -314,7 +314,7 @@ impl ScannerIOCache for SetDisks {
         let ctx_clone = ctx.clone();
         let completed_bucket_count = Arc::new(AtomicUsize::new(0));
         let completed_bucket_count_clone = completed_bucket_count.clone();
-        let collect_bucket_results_fut = tokio::spawn(async move {
+        let collect_bucket_results_fut = AbortOnDropHandle::new(tokio::spawn(async move {
             let mut cancelled = false;
 
             loop {
@@ -333,7 +333,7 @@ impl ScannerIOCache for SetDisks {
                     }
                 }
             }
-        });
+        }));
 
         let mut futs = Vec::new();
 
@@ -365,7 +365,7 @@ impl ScannerIOCache for SetDisks {
                 NamespaceScannerWorkerMode::RemoteV4(server_epoch) => Some(server_epoch),
                 NamespaceScannerWorkerMode::Coordinator => None,
             };
-            futs.push(tokio::spawn(async move {
+            futs.push(AbortOnDropHandle::new(tokio::spawn(async move {
                 let remote_session_id = uuid::Uuid::new_v4();
                 let mut remote_session_sequence = 0_u64;
                 loop {
@@ -1038,7 +1038,7 @@ impl ScannerIOCache for SetDisks {
                         );
                     }
                 }
-            }));
+            })));
         }
         drop(bucket_tx);
         drop(bucket_result_tx);

crates/scanner/src/scanner_io/io_cycle.rs

@@ -242,7 +242,7 @@ impl ScannerIOCycle for ECStore {
                         results[results_index_clone] = result;
                     }
                 });
-                wait_futs.push(receiver_fut);
+                wait_futs.push(AbortOnDropHandle::new(receiver_fut));
 
                 let scan_plan = ScannerBucketScanPlan {
                     buckets: set_buckets,
@@ -318,7 +318,7 @@ impl ScannerIOCycle for ECStore {
                         record_set_scan_failure(&mut first_err, e);
                     }
                 });
-                wait_futs.push(scanner_fut);
+                wait_futs.push(AbortOnDropHandle::new(scanner_fut));
             }
         }