From: Chuck Lever <chuck.lever@oracle.com>
Date: Mon, 19 Apr 2021 14:02:03 -0400
Subject: [PATCH] xprtrdma: Avoid Receive Queue wrapping
Git-commit: 32e6b68167f1d446111c973d57e6f52aee11897a
Patch-mainline: v5.13-rc1
References: git-fixes

Commit e340c2d6ef2a ("xprtrdma: Reduce the doorbell rate (Receive)")
increased the number of Receive WRs that are posted by the client,
but did not increase the size of the Receive Queue allocated during
transport set-up.

This is usually not an issue because RPCRDMA_BACKWARD_WRS is defined
as (32) when SUNRPC_BACKCHANNEL is defined. In cases where it isn't,
there is a real risk of Receive Queue wrapping.

Fixes: e340c2d6ef2a ("xprtrdma: Reduce the doorbell rate (Receive)")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Tom Talpey <tom@talpey.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 net/sunrpc/xprtrdma/frwr_ops.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -248,6 +248,7 @@ int frwr_open(struct rpcrdma_ia *ia, str
 	ep->rep_attr.cap.max_send_wr += 1; /* for ib_drain_sq */
 	ep->rep_attr.cap.max_recv_wr = ep->rep_max_requests;
 	ep->rep_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
+	ep->rep_attr.cap.max_recv_wr += RPCRDMA_MAX_RECV_BATCH;
 	ep->rep_attr.cap.max_recv_wr += 1; /* for ib_drain_rq */
 
 	ia->ri_max_segs =