Re: [PATCH] 2.4.20 Direct IO patch for NFS. (Note: a trivial API

[Andrew Morton]

Christoph Hellwig wrote:
> 
> On Mon, Sep 30, 2002 at 08:34:04PM +0200, Trond Myklebust wrote:
> >
> > Hi Marcelo,
> >
> >   The following patch implements direct I/O for NFS as a compilation option.
> > It does not in any way touch the standard NFS read/write code, however it
> > does change the interface for generic direct I/O: Instead of taking a
> > 'struct inode' argument, we need to take the full 'struct file' in order
> > to be able to pass the RPC credential information down to the NFS layer.
> 
> I don't think changing the filesystem entry points during 2.4 is an option.
> 

It's a very small change; I wouldn't be very fussed about it personally.

To be source-compatible with out-of-kernel filesystems you could add
a new a_op and do

	if (mapping->direct_IO_which_uses_a_filp)
		use that
	else
		use mapping->direct_IO

but ick.