switch create_read_pipe() to alloc_file()

struct file *create_read_pipe(struct file *wrf, int flags)

{

	struct file *f = get_empty_filp();

	/* Grab pipe from the writer */

	struct file *f = alloc_file(&wrf->f_path, FMODE_READ,

				    &read_pipefifo_fops);

	if (!f)

		return ERR_PTR(-ENFILE);

	/* Grab pipe from the writer */

	f->f_path = wrf->f_path;

	path_get(&wrf->f_path);

	f->f_mapping = wrf->f_path.dentry->d_inode->i_mapping;

	f->f_pos = 0;

	f->f_flags = O_RDONLY | (flags & O_NONBLOCK);

	f->f_op = &read_pipefifo_fops;

	f->f_mode = FMODE_READ;

	f->f_version = 0;

	return f;

}