z3fold: simplify the zhdr initialization code in init_z3fold_page()

We can simplify the zhdr initialization by memset() the zhdr first
instead of set struct member to zero one by one.  This would also make
code more compact and clear.

Link: https://lkml.kernel.org/r/20210120085851.16159-1-linmiaohe@huawei.comSigned-off-by: NMiaohe Lin <linmiaohe@huawei.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/z3fold.c

@@ -413,16 +413,10 @@ static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
 	if (!slots)
 		return NULL;
 
+	memset(zhdr, 0, sizeof(*zhdr));
 	spin_lock_init(&zhdr->page_lock);
 	kref_init(&zhdr->refcount);
-	zhdr->first_chunks = 0;
-	zhdr->middle_chunks = 0;
-	zhdr->last_chunks = 0;
-	zhdr->first_num = 0;
-	zhdr->start_middle = 0;
 	zhdr->cpu = -1;
-	zhdr->foreign_handles = 0;
-	zhdr->mapped_count = 0;
 	zhdr->slots = slots;
 	zhdr->pool = pool;
 	INIT_LIST_HEAD(&zhdr->buddy);