The trouble with discard

Yes. My original line of thought was that remapping a block to be written to a place of an already written and valid block requires more writes than just writing that block to a free location, which I thought was defeating the purpose. But I was overlooking the fact that while the scheme would require more writes indeed, it would nevertheless allow scattering wear evenly. Thanks for pointing that out; the other thing to point out is that lwn has got a great user base!