btrfs: Replace multiple atomic_inc() with atomic_add()

This patch replaces multiple atomic_inc() with atomic_add() in
delayed-inode.c to reduce source code and have few instructions
for compilation.

Reviewed-by: Zach Brown <zab@redhat.com>
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/delayed-inode.c

@@ -108,8 +108,8 @@ static struct btrfs_delayed_node *btrfs_get_delayed_node(struct inode *inode)
 			return node;
 		}
 		btrfs_inode->delayed_node = node;
-		atomic_inc(&node->refs);	/* can be accessed */
-		atomic_inc(&node->refs);	/* cached in the inode */
+		/* can be accessed and cached in the inode */
+		atomic_add(2, &node->refs);
 		spin_unlock(&root->inode_lock);
 		return node;
 	}
@@ -138,8 +138,8 @@ again:
 		return ERR_PTR(-ENOMEM);
 	btrfs_init_delayed_node(node, root, ino);
 
-	atomic_inc(&node->refs);	/* cached in the btrfs inode */
-	atomic_inc(&node->refs);	/* can be accessed */
+	/* cached in the btrfs inode and can be accessed */
+	atomic_add(2, &node->refs);
 
 	ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
 	if (ret) {