Re: [fuse-devel] Re: NFS and direct_io (another oops)

[David S. <ds...@ja...>]

On Fri, Apr 08, 2005 at 06:39:25PM +0200, Miklos Szeredi wrote:
> > > In testing, I've found what seems to be a problem with NFS and the
> > > direct_io option.  Basically, without direct_io, a regular fuse mount
> > > works as expected over NFS.  When flipping direct_io on, the sequence
> > > of events for a cp onto an already-existing file is:
> > > 
> > >   GETATTR /file
> > >   TRUNCATE /file to 0
> > >   OPEN /file with flags 100001
> > > 
> > > then nothing.  The cp just blocks at that point and the filesystem
> > > program gets no further calls.
> > 
> > We found another oops behind this problem:
> 
> Great.  This fix will just return an error for direct_io writes over
> nfs.  I'm not sure it's feasable to fix it any further.

Thanks for the patch.  Can you explain further what the problem is
here?  For my usage, I do need to have a direct_io mount, since I do
not know the size of files in advance.  This is just a read issue, of
course.  Is there some way to use direct_io for reads, but not for
writes?

David