io/uring/Operation: add method GetUringData()

src/io/uring/Operation.hxx

@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <cassert>
+
 namespace Uring {
 
 class CancellableOperation;
@@ -33,6 +35,16 @@ public:
 		return cancellable != nullptr;
 	}
 
+	/**
+	 * Returns the data pointer that can be passed to
+	 * io_uring_prep_cancel().
+	 */
+	void *GetUringData() const noexcept {
+		assert(IsUringPending());
+
+		return cancellable;
+	}
+
 	/**
 	 * Cancel the operation.  OnUringCompletion() will not be
 	 * invoked.  This is a no-op if none is pending.