feat(ecstore): expose rename sync tail metrics (#6257)

Add default-off PUT stage helpers for fdatasync batch shape and rename quorum fanout shape so #925 follow-up probes can distinguish shard sync batching opportunities from fanout convergence.

Co-authored-by: heihutu <heihutu@gmail.com>

crates/ecstore/src/disk/os.rs

@@ -1098,6 +1098,10 @@ pub(crate) async fn sync_dir_files_with_limiter(dir: impl AsRef<Path>, disk_perm
     let files = run_file_sync_blocking(disk_permits.clone(), move || {
         let files = regular_files(&scan_dir)?;
         if files.len() < PARALLEL_FILE_SYNC_THRESHOLD {
+            rustfs_io_metrics::record_put_rename_fdatasync_batch(
+                rustfs_io_metrics::PUT_RENAME_FDATASYNC_BATCH_MODE_SERIAL,
+                files.len(),
+            );
             sync_files(&files)?;
             let fsync_started = rustfs_io_metrics::put_stage_timer();
             let result = fsync_dir_std(scan_dir);
@@ -1115,6 +1119,10 @@ pub(crate) async fn sync_dir_files_with_limiter(dir: impl AsRef<Path>, disk_perm
     let Some(files) = files else {
         return Ok(());
     };
+    rustfs_io_metrics::record_put_rename_fdatasync_batch(
+        rustfs_io_metrics::PUT_RENAME_FDATASYNC_BATCH_MODE_PARALLEL,
+        files.len(),
+    );
     futures::stream::iter(files.into_iter().map(Ok::<_, io::Error>))
         .try_for_each_concurrent(MAX_PARALLEL_FILE_SYNCS, |path| {
             let disk_permits = disk_permits.clone();

crates/ecstore/src/set_disk/core/io_primitives.rs

@@ -3417,6 +3417,25 @@ impl SetDisks {
             quorum_wait_started,
         );
         let (results, mut file_infos) = fanout_result.map_err(|_| DiskError::Unexpected)?;
+        if rustfs_io_metrics::put_stage_metrics_enabled() {
+            let mut fanout_success = 0;
+            let mut fanout_error = 0;
+            let mut fanout_panic = 0;
+            for result in &results {
+                match result {
+                    Ok(Ok(_)) => fanout_success += 1,
+                    Ok(Err(_)) => fanout_error += 1,
+                    Err(_) => fanout_panic += 1,
+                }
+            }
+            rustfs_io_metrics::record_put_rename_quorum_wait_fanout(
+                results.len(),
+                write_quorum,
+                fanout_success,
+                fanout_error,
+                fanout_panic,
+            );
+        }
 
         for (idx, result) in results.iter().enumerate() {
             match result {