In my experience a good FAL is about as hard to write as a good filesystem.
While you can parameterize a lot of things, there are some fundamental properties of the flash cells which make it very hard to write a single FAL which works well with all flash chips.
As a matter of principle I do not comment on issues specific to Linux.
So just an inch to the left goalpost of the True Scotsman's "filesystem" definition.
> make it very hard to write a single FAL which works well with all flash chips
Right? So the last thing you want is to foist that logic into filesystems. The layered separation is good.
Hence, someone upthread wrote: A flash adaptation layer solves the following problem: I have M filesystems, that I'd like to use on any one of N different flash technologies. I don't want to complicate each M filesystem with support for N flashes.
Today SSD's expose a datamodel which makes them look like disks.
To implement that datamodel, on a storage substrate which have radically different semantics, they have to implement what is essentially a (log-structured-)filesystem.
(I happen know this first hand, because I have worked on both file-systems and FALs.)
And that is why I say we have two filesystems stacked on each other.
Your limited understanding of filesystems does not change reality.
Over & out.