backing_file_splice_read
EXPORT_SYMBOL_GPL(backing_file_splice_read);
ret = backing_file_splice_read(backing_file, &iocb, pipe, len, flags, &ctx);
ret = backing_file_splice_read(realfile, &iocb, pipe, len, flags, &ctx);
ssize_t backing_file_splice_read(struct file *in, struct kiocb *iocb,