jbd2: use kmem_cache_zalloc instead of kmem_cache_alloc/memset

The jbd2_alloc_handle() function is only called by new_handle().  So
this commit uses kmem_cache_zalloc() instead of
kmem_cache_alloc()/memset().

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index f9fe889..6e051f4 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1145,7 +1145,7 @@
 
 static inline handle_t *jbd2_alloc_handle(gfp_t gfp_flags)
 {
-	return kmem_cache_alloc(jbd2_handle_cache, gfp_flags);
+	return kmem_cache_zalloc(jbd2_handle_cache, gfp_flags);
 }
 
 static inline void jbd2_free_handle(handle_t *handle)