linux-kernel - [PATCH v6 6/7] nfsd: handle NFS4ERR_BADSLOT on CB

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Message-Id: <20250209-nfsd-6-14-v6-6-396dd1bed647@kernel.org>
Date: Sun, 09 Feb 2025 07:31:27 -0500
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>, Neil Brown <neilb@...e.de>, 
 Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>, 
 Tom Talpey <tom@...pey.com>, "J. Bruce Fields" <bfields@...ldses.org>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jeff Layton <jlayton@...nel.org>
Subject: [PATCH v6 6/7] nfsd: handle NFS4ERR_BADSLOT on CB_SEQUENCE better

Currently it just restarts the call, without getting a new slot.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 fs/nfsd/nfs4callback.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 18803ebe2bddd433308cabd6f99b64ec887069a7..8ba1a2831e8601ac3af9c5f147d3dcddcc1bec77 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -1389,6 +1389,13 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback
 		rpc_delay(task, 2 * HZ);
 		return false;
 	case -NFS4ERR_BADSLOT:
+		/*
+		 * BADSLOT means that the client and server are out of sync
+		 * as to the backchannel parameters. Mark the backchannel faulty
+		 * and restart the RPC, but leak the slot so no one uses it.
+		 */
+		nfsd4_mark_cb_fault(cb->cb_clp);
+		cb->cb_held_slot = -1;
 		goto retry_nowait;
 	case -NFS4ERR_SEQ_MISORDERED:
 		if (session->se_cb_seq_nr[cb->cb_held_slot] != 1) {

-- 
2.48.1