jbd: use kmem_cache_zalloc instead of kmem_cache_alloc/memset

Now jbd_alloc_handle is only called by new_handle.  So this commit
uses kmem_cache_zalloc instead of kmem_cache_alloc/memset.
Signed-off-by: NZheng Liu <wenqing.lz@taobao.com>
Signed-off-by: NJan Kara <jack@suse.cz>

fs/jbd/transaction.c

@@ -245,7 +245,6 @@ static handle_t *new_handle(int nblocks)
 	handle_t *handle = jbd_alloc_handle(GFP_NOFS);
 	if (!handle)
 		return NULL;
-	memset(handle, 0, sizeof(*handle));
 	handle->h_buffer_credits = nblocks;
 	handle->h_ref = 1;
 

include/linux/jbd.h

@@ -887,7 +887,7 @@ extern struct kmem_cache *jbd_handle_cache;
 
 static inline handle_t *jbd_alloc_handle(gfp_t gfp_flags)
 {
-	return kmem_cache_alloc(jbd_handle_cache, gfp_flags);
+	return kmem_cache_zalloc(jbd_handle_cache, gfp_flags);
 }
 
 static inline void jbd_free_handle(handle_t *handle)