UBI/UBIFS: dealing with MLC's paired pages

[Artem Bityutskiy]

On Fri, 2015-10-30 at 10:45 +0100, Boris Brezillon wrote:
> Moreover, the standard GC only takes place when you can't find a free
> LEB anymore, which will probably happen when you reach something
> close
> to half the partition size in case of MLC chips (it may be a bit
> higher if you managed to occupy more than half of each LEB capacity).
> This means that your FS will become slower when you reach this limit,
> though maybe this can be addressed by triggering the GC before we run
> out of free LEBs.

Right. I'd call it a detail. But the big picture is - if you have to GC
all the data you write, you write twice. When exactly you do the second
write is a detail - sometimes it is deferred, it is in background etc,
sometimes right away - you have to GC older data before being able to
write new data.

Now, by no means I am criticizing you or your decisions, you are doing
great job. I am more like summarizing and trying to give you some food
for thoughts. :-)