Re: [PATCH 1/2] NFSv4: Servers should only check SETATTR stateid open mode on size change

["J. Bruce Fields" <bfields@fieldses.org>]

On Mon, Apr 29, 2013 at 06:33:02PM +0000, Myklebust, Trond wrote:
> On Mon, 2013-04-29 at 14:29 -0400, J. Bruce Fields wrote:
> > On Mon, Apr 29, 2013 at 06:27:07PM +0000, Myklebust, Trond wrote:
> > > On Mon, 2013-04-29 at 14:21 -0400, J. Bruce Fields wrote:
> > > > On Mon, Apr 29, 2013 at 06:15:52PM +0000, Myklebust, Trond wrote:
> > > > > On Mon, 2013-04-29 at 11:15 -0400, Trond Myklebust wrote:
> > > > > > The NFSv4 and NFSv4.1 specs are both clear that the server should only check
> > > > > > stateid open mode if a SETATTR specifies the size attribute. If the
> > > > > > open mode is not one that allows writing, then it returns NFS4ERR_OPENMODE.
> > > > > > 
> > > > > > In the case where the SETATTR is not changing the size, the client will
> > > > > > still pass it the delegation stateid to ensure that the server does not
> > > > > > recall that delegation. In that case, the server should _ignore_ the
> > > > > > delegation open mode, and simply apply standard permission checks.
> > > > > 
> > > > > Bruce, what does the Linux server do when we send it a delegation
> > > > > stateid as part of a SETATTR that just changes the mode or acl (no size
> > > > > change)? Will it recall the delegation? How about the delegations held
> > > > > by other clients?
> > > > 
> > > > Yes, it breaks all delegations on any setattr.
> > > 
> > > Do you plan to change that?
> > 
> > I'd take patches.
> 
> Have the NFSv4 delegation patches been merged yet, and do they hand out
> delegations on file creation?

The vfs support patches haven't been merged, but nfsd still continues to
give out read delegations on any confirmed read-open of a file that
hasn't had a recent delegation conflict.  (They're just not consistent
w.r.t local metadata operations....)

--b.