Re: [PATCH] nfs: fix nfs_writepage()

[Trond Myklebust <trond.myklebust@fys.uio.no>]

On Wed, 2007-10-17 at 11:45 -0400, Trond Myklebust wrote:
> On Wed, 2007-10-17 at 17:30 +0200, Peter Zijlstra wrote:
> 
> > The thing is, swapper_space just calls ->writepage() and expects the
> > page to be written out. So either the a_ops usage of swapper_space is
> > deviant or NFS' is.
> 
> Could somebody please document WTF writepage() is supposed to do, and
> WTF page_mkwrite() is for?
> 
> I thought that page_mkwrite() was supposed to finally allow us to deal
> with dirty pages in a clean manner: the caller gets to tell the
> filesystem that it wants the entire page written out, and then dirties
> the page. What is the point if the VM then expects to be able to
> circumvent this?

Put differently:
      * _who_ is dirtying the page when the swapper is trying to write
        the page out?
      * why are they not calling either page_mkwrite() or
        commit_write()?

Trond