fix: address correctness, safety, and concurrency issues (#2327)

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

rustfs/src/storage/ecfs_extend.rs

@@ -187,7 +187,6 @@ pub(crate) fn get_buffer_size_opt_in(file_size: i64) -> usize {
     };
 
     // Optional performance metrics collection for monitoring and optimization
-    #[cfg(feature = "metrics")]
     {
         use metrics::histogram;
         histogram!("rustfs.buffer.size.bytes").record(buffer_size as f64);