Closed
Description
ATM EA.fillna handles both a) fillna(scalar), b) ffill/bfill, and c) interpolate (which is mostly broken except for ffill/bfill (which I think should not go through interpolate xref #53581) xref #50950)
At the NDFrame level we have four separate methods: ffill, bfill, fillna, interpolate. I think it makes sense to just have the same four methods all the way down the stack (Manager, Block, EA). I'd also be OK with ffill/bfill being combined into e.g. pad_or_backfill for the internal classes.