On Sun, Sep 20, 2020 at 4:23 PM Dave Chinner [off-list ref] wrote:

FWIW, if the fs layer is already providing this level of IO
exclusion w.r.t. address space access, does it need to be replicated
at the address space level?

Honestly, I'd rather do it the other way, and go "if the vfs layer
were to provide the IO exclusion, maybe the filesystems can drop it?

Because we end up having something like 60 different filesystems. It's
*really* hard to know that "Yeah, this filesystem does it right".

And if we do end up doing it at both levels, and end up having some of
the locking duplicated, that's still better than "sometimes we don't
do it at all", and have odd problems on the less usual (and often less
well maintained) filesystems..

              Linus