os/bluestore: Add fast-path optimization in Blob::put() by checking nref == 1

Add fast-path optimization in `Blob::put()` for intrusive pointer by checking
`nref == 1` using an acquire load before decrementing.
Reduces atomic overhead in common last-reference cases, improving performance

Signed-off-by: Jaya Prakash <[email protected]>

Author: Jayaprakash-ibm

src/os/bluestore/BlueStore.h

@@ -762,6 +762,10 @@ class BlueStore : public ObjectStore,
       ++nref;
     }
     void put() {
+      if (nref.load(std::memory_order_acquire) == 1) {
+        delete this;
+        return;
+      }
       if (--nref == 0)
 	delete this;
     }