Write about what you love?

I started reading IQ84 by Haruki Murakami recently, and one of the characters is a struggling writer. I am enjoying it quite a lot more than the previous Murakami novel I read, though it has a lot of similarities also.

I wonder, though, how many writers write about writers? How many characters in novels are writers themselves? The common advice is to ‘write what you know’, and every writer knows about being a writer…

Reading it though, has made me want to have a writer character. Maybe that character’s character is also a writer, too. How deep could you go before confusing the reader, I wonder..