The RIAA has unsuccessfully tried to claim that "making available(for download)" is infringement. So there would need to be some amount of actual uploading to p

The RIAA has unsuccessfully tried to claim that "making available(for download)" is infringement. So there would need to be some amount of actual uploading to prove this as a civil case. But even if you only seed while downloading it is likely even the relatively small amount uploaded would meet the legal requirement, the law does not require that you distributed a full copy of a particular work. Ultimately whether a specific amount would be enough would come down to the judge or jury.