Prefaulting for i/o buffers

[Konstantin Belousov]

On Thu, Mar 01, 2012 at 03:12:47PM +0100, Pawel Jakub Dawidek wrote:
> On Thu, Mar 01, 2012 at 01:16:24PM +0200, Gleb Kurtsou wrote:
> > On (25/02/2012 20:46), Pawel Jakub Dawidek wrote:
> > > - "Every file system needs cache. Let's make it general, so that all file
> > >   systems can use it!" Well, for VFS each file system is a separate
> > >   entity, which is not the case for ZFS. ZFS can cache one block only
> > >   once that is used by one file system, 10 clones and 100 snapshots,
> > >   which all are separate mount points from VFS perspective.
> > >   The same block would be cached 111 times by the buffer cache.
> > 
> > Hmm. But this one is optional. Use vop_cachedlookup (or call
> > cache_entry() on your own), add a number of cache_prune calls. It's
> > pretty much library-like design you describe below.
> 
> Yes, namecache is already library-like, but I was talking about the
> buffer cache. I managed to bypass it eventually with suggestions from
> ups@, but for a long time I was sure it isn't at all possible.

I am quite curious, in which way buffer layer is mandatory ?
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