perf(ecstore): batch local EC shard preads on GET (#5679)

Collapse per-shard blocking-pool round-trips into one spawn_blocking
pread batch when all online shards are local and mmap-read is enabled.

Co-authored-by: ba <ba@ubuntu-server.alpha30.bos16>
Co-authored-by: Zhengchao An <anzhengchao@gmail.com>

crates/ecstore/src/disk/mod.rs

@@ -682,6 +682,15 @@ impl Disk {
             Disk::Remote(remote_disk) => remote_disk.enable_health_check(),
         }
     }
+
+    /// Returns the absolute filesystem path for a (volume, path) pair if this
+    /// disk is local, or `None` if it is a remote disk.
+    pub fn get_object_path_if_local(&self, volume: &str, path: &str) -> Option<crate::disk::error::Result<std::path::PathBuf>> {
+        match self {
+            Disk::Local(w) => Some(w.get_object_path_if_local(volume, path)),
+            Disk::Remote(_) => None,
+        }
+    }
 }
 
 pub async fn new_disk(ep: &Endpoint, opt: &DiskOption) -> Result<DiskStore> {