3.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "J. Bruce Fields" <redacted>

commit c30e92df30d7d5fe65262fbce5d1b7de675fe34e upstream.

We don't use WANT bits yet--and sending them can probably trigger a
BUG() further down.

Signed-off-by: J. Bruce Fields <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 fs/nfsd/nfs4state.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c

@@ -3570,6 +3570,8 @@ nfsd4_open_downgrade(struct svc_rqst *rq
 	if (!access_valid(od->od_share_access, cstate->minorversion)
 			|| !deny_valid(od->od_share_deny))
 		return nfserr_inval;
+	/* We don't yet support WANT bits: */
+	od->od_share_access &= NFS4_SHARE_ACCESS_MASK;
 
 	nfs4_lock_state();
 	if ((status = nfs4_preprocess_seqid_op(cstate,