jffs2: Use kzalloc instead of kmalloc/memset

Use kzalloc rather than duplicating its implementation, which
makes code simple and easy to understand.
Signed-off-by: Haowen Bai <baihaowen@meizu.com>
[rw: Fixed printk string]
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/jffs2/erase.c

@@ -43,9 +43,9 @@ static void jffs2_erase_block(struct jffs2_sb_info *c,
 	jffs2_dbg(1, "%s(): erase block %#08x (range %#08x-%#08x)\n",
 		  __func__,
 		  jeb->offset, jeb->offset, jeb->offset + c->sector_size);
-	instr = kmalloc(sizeof(struct erase_info), GFP_KERNEL);
+	instr = kzalloc(sizeof(struct erase_info), GFP_KERNEL);
 	if (!instr) {
-		pr_warn("kmalloc for struct erase_info in jffs2_erase_block failed. Refiling block for later\n");
+		pr_warn("kzalloc for struct erase_info in jffs2_erase_block failed. Refiling block for later\n");
 		mutex_lock(&c->erase_free_sem);
 		spin_lock(&c->erase_completion_lock);
 		list_move(&jeb->list, &c->erase_pending_list);
@@ -57,8 +57,6 @@ static void jffs2_erase_block(struct jffs2_sb_info *c,
 		return;
 	}
 
-	memset(instr, 0, sizeof(*instr));
-
 	instr->addr = jeb->offset;
 	instr->len = c->sector_size;