Re: [PATCH v1] nfs: Don't increment lock sequence ID after NFS4ERR_MOVED

[bfields@fieldses.org (J. Bruce Fields)]

On Mon, Jan 23, 2017 at 10:01:27AM -0500, Chuck Lever wrote:
> 
> > On Jan 22, 2017, at 2:04 PM, Chuck Lever <chuck.lever@oracle.com> wrote:
> > 
> > Xuan Qi reports that the Linux NFSv4 client failed to lock a file
> > that was migrated. The steps he observed on the wire:
> > 
> > 1. The client sent a LOCK request
> > 2. The server replied NFS4ERR_MOVED
> > 3. The client switched to the destination server
> > 4. The client sent the LOCK request again with a bumped
> >   lock sequence ID
> > 5. The server rejected the LOCK request with NFS4ERR_BAD_SEQID
> 
> The list of steps could be more clear:
> 
> 1. The client sent a LOCK request to the source server
> 2. The source server replied NFS4ERR_MOVED
> 3. The client switched to the destination server
> 4. The client sent the same LOCK request to the destination
>    server with a bumped lock sequence ID
> 5. The destination server rejected the LOCK request with
>    NFS4ERR_BAD_SEQID
> 
> 
> > RFC 3530 section 8.1.5 provides a list of NFS errors which do not
> > bump a lock sequence ID.
> > 
> > However, RFC 3530 is now obsoleted by RFC 7530. In RFC 7530 section
> > 9.1.7, this list has been updated by the addition of NFS4ERR_MOVED.

I guess we figured the backwards-incompatible change was OK since
essentially the Solaris server is the first we know of to be making real
use of NFS4ERR_MOVED?

And probably it's required for the their implementation because the old
server no longer has the ability to update the state once it's reached
the point of returning ERR_MOVED.

OK, makes sense to me, I think.

--b.

> > 
> > Reported-by: Xuan Qi <xuan.qi@oracle.com>
> > Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> > Cc: stable@vger.kernel.org # v3.7+
> > ---
> > include/linux/nfs4.h |    3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
> > index bca5363..1b1ca04 100644
> > --- a/include/linux/nfs4.h
> > +++ b/include/linux/nfs4.h
> > @@ -282,7 +282,7 @@ enum nfsstat4 {
> > 
> > static inline bool seqid_mutating_err(u32 err)
> > {
> > -	/* rfc 3530 section 8.1.5: */
> > +	/* See RFC 7530, section 9.1.7 */
> > 	switch (err) {
> > 	case NFS4ERR_STALE_CLIENTID:
> > 	case NFS4ERR_STALE_STATEID:
> > @@ -291,6 +291,7 @@ static inline bool seqid_mutating_err(u32 err)
> > 	case NFS4ERR_BADXDR:
> > 	case NFS4ERR_RESOURCE:
> > 	case NFS4ERR_NOFILEHANDLE:
> > +	case NFS4ERR_MOVED:
> > 		return false;
> > 	};
> > 	return true;
> > 
> > --
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> 
> --
> Chuck Lever
> 
> 
> 
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