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

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

On Tue, Jan 24, 2017 at 02:06:16PM -0500, Chuck Lever wrote:
> 
> > On Jan 23, 2017, at 11:49 AM, bfields@fieldses.org wrote:
> > 
> > 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.
> 
> Hi Bruce-
> 
> Does this mean you will take this patch, or should
> I just add your Reviewed-by: ?

I can take it if nobody objects.  Mind if I append the above to the
changelog?  (Just want to document why we think the apparently
backwards-incompatible change is OK.)

--b.

> 
> 
> > --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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> > --
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> 
> --
> Chuck Lever
> 
>