Re: [PATCH v2 2/2] fuse: remove tmp folio for writebacks and internal rb tree

[Shakeel Butt <shakeel.butt@linux.dev>]

On Wed, Oct 16, 2024 at 11:51:39AM GMT, Miklos Szeredi wrote:
> On Tue, 15 Oct 2024 at 21:17, Shakeel Butt <shakeel.butt@linux.dev> wrote:
> 
> > So, any operation that the fuse server can do which can cause wait on
> > writeback on the folios backed by the fuse is problematic. We know about
> > one scenario i.e. memory allocation causing reclaim which may do the
> > wait on unrelated folios which may be backed by the fuse server.
> >
> > Now there are ways fuse server can shoot itself on the foot. Like sync()
> > syscall or accessing the folios backed by itself. The quesion is should
> > we really need to protect fuse from such cases?
> 
> That's not the issue with sync(2).  The issue is that a fuse server
> can deny service to an unrelated and possibly higher privilege task by
> blocking writeback.  We really don't want that to happen.

If I understand you correctly, you are saying fuse server doing wrong
things like accessing the files it is serving is not something we need
to care about. More specifically all the operations which directly
manipulates the folios it is serving (like migration) should be ignored.
Is this correct?