[Linux-cachefs] Re: [PATCH] NFS using CacheFS

[David Howells]

Trond Myklebust <trond.myklebust at fys.uio.no> wrote:
> That said, David & co.: why did you choose not to use something similar
> to the Solaris syntax for cachefs?

Well...

  (1) when I wrote cachefs I didn't know that Solaris had such a thing

  (2) I don't know what Solaris syntax is - I've seen one example, and that
      didn't make a lot of sense

  (3) my way doesn't involve any changes to userspace programs such as mount

> The "layered filesystem" syntax has the advantage that it would avoid
> entirely the need to change the NFS mount syntax,

And the disadvantage that we'd have to change the VFS to support it, I
think. I don't know how this "layered filesystem" thing operates or is used,
so I'm guessing.

> and would make it easier to port cachefs to cifs etc.

I doubt it. The netfs still has to interact with fscache internally to decide
how match netfs files to cache files, which is what most of the interface is
about; and to push/pull pages to/from the cache (this bit could possibly be
made transparent, but I'm not sure how you'd do it on Linux with the present
VM & VFS interfaces).

David