[PATCH 3/4] SUNRPC: Allow for some re-ordering of RPCSEC_GSS requests on the server

[Trond Myklebust <trondmy@gmail.com>]

Strictly speaking, the client is probably not supposed to transmit more
requests than are allowed for in the RPCSEC_GSS window. However since
we do, try to ensure that we allow for some re-ordering by the server.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 net/sunrpc/auth_gss/auth_gss.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index ba765473d1f0..dc7124d45c8a 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -2029,9 +2029,6 @@ gss_xmit_need_reencode(struct rpc_task *task)
 	if (!ctx)
 		return true;
 
-	if (gss_seq_is_newer(req->rq_seqno, READ_ONCE(ctx->gc_seq)))
-		goto out;
-
 	seq_xmit = READ_ONCE(ctx->gc_seq_xmit);
 	while (gss_seq_is_newer(req->rq_seqno, seq_xmit)) {
 		u32 tmp = seq_xmit;
@@ -2043,7 +2040,12 @@ gss_xmit_need_reencode(struct rpc_task *task)
 		}
 	}
 
-	win = ctx->gc_win;
+	/*
+	 * Ensure the request is within 3/4 of the RPCSEC_GSS sequence
+	 * window so that we allow for some re-ordering of the requests
+	 * by the server.
+	 */
+	win = 3 * ((ctx->gc_win + 3) >> 2);
 	if (win > 0)
 		ret = !gss_seq_is_newer(req->rq_seqno, seq_xmit - win);
 out:
-- 
2.20.1