Utility man Roberto has enjoyed a few more opportunities in his favoured midfield position under Ernesto Valverde this season.
The 25-year-old returned from a hamstring injury at right-back, playing 90 minutes in Saturday's 2-2 La Liga draw against Celta Vigo.
"The negotiations are going well. I've been a Barca person since I was a kid so I think we should be able to reach an agreement without any problems," he told a news conference ahead of Tuesday's Champions League match against Sporting CP.
"There are always small things to discuss. That is what we are talking about in meetings, but I think everything is under control."
Barcelona are already through to the knockout stages as Group D winners but Valverde has a selection headache at centre-back, with Samuel Umtiti facing eight weeks out due to a hamstring injury.
Veteran Javier Mascherano is still out with a similar complaint, leaving Gerard Pique and the injury-prone Thomas Vermaelen as the remaining senior centre-back options.
Despite his adaptability, Roberto does not think he is a candidate to step into the heart of defence.
"I've never played at centre-back before. It's obviously bad for us that Umtiti is injured but, whenever we have injuries, us players pull together," he added.
"We've got a deep squad with people who can play in different positions and do a very good job.
"At the moment, I don't really see myself as a centre-back but the players that do, I'm sure they will do a very good job in that position."