Think this is the one you mean
http://www.fourfourtwo.com/news/martinez-outlines-barcelona-buy-back-options-deulofeu
The player cannot be bought back in January, nor could Barcelona swoop for Deulofeu simply to sell him on immediately for a profit.
"They can't do that," he explained at a news conference. "There are certain things in the deal. They can't take him back in the winter so they can't take him back in January. It can only be at the end of the season. It is €9m for the first year and €12m in the second year.
"If they take him back they can't sell him for a season, so he has to stay in the first-team squad for a season. At the end of that if they decide to sell him we have got first rights of getting him back or we have got a big percentage of that deal.
"There is nothing we can do if they activate it. That was the deal and the only way we could access the player in the terms that we wanted. I'm delighted with the deal."