Commit 913fadc5 authored by Anna Schumaker's avatar Anna Schumaker
Browse files

NFS: Fix interrupted slots by sending a solo SEQUENCE operation 



We used to do this before 3453d570, but this was changed to better
handle the NFS4ERR_SEQ_MISORDERED error code. This commit fixed the slot
re-use case when the server doesn't receive the interrupted operation,
but if the server does receive the operation then it could still end up
replying to the client with mis-matched operations from the reply cache.

We can fix this by sending a SEQUENCE to the server while recovering from
a SEQ_MISORDERED error when we detect that we are in an interrupted slot
situation.

Fixes: 3453d570 (NFSv4.1: Avoid false retries when RPC calls are interrupted)
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent af667527

fs/nfs/nfs4proc.c

+18 −2
Original line number Diff line number Diff line
@@ -774,6 +774,14 @@ static void nfs4_slot_sequence_acked(struct nfs4_slot *slot, 
	slot->seq_nr_last_acked = seqnr;

}



static void nfs4_probe_sequence(struct nfs_client *client, const struct cred *cred,

				struct nfs4_slot *slot)

{

	struct rpc_task *task = _nfs41_proc_sequence(client, cred, slot, true);

	if (!IS_ERR(task))

		rpc_put_task_async(task);

}



static int nfs41_sequence_process(struct rpc_task *task,

		struct nfs4_sequence_res *res)

{
@@ -790,6 +798,7 @@ static int nfs41_sequence_process(struct rpc_task *task, 
		goto out;



	session = slot->table->session;

	clp = session->clp;



	trace_nfs4_sequence_done(session, res);
@@ -804,7 +813,6 @@ static int nfs41_sequence_process(struct rpc_task *task, 
		nfs4_slot_sequence_acked(slot, slot->seq_nr);

		/* Update the slot's sequence and clientid lease timer */

		slot->seq_done = 1;

		clp = session->clp;

		do_renew_lease(clp, res->sr_timestamp);

		/* Check sequence flags */

		nfs41_handle_sequence_flag_errors(clp, res->sr_status_flags,
@@ -852,10 +860,18 @@ static int nfs41_sequence_process(struct rpc_task *task, 
		/*

		 * Were one or more calls using this slot interrupted?

		 * If the server never received the request, then our

		 * transmitted slot sequence number may be too high.

		 * transmitted slot sequence number may be too high. However,

		 * if the server did receive the request then it might

		 * accidentally give us a reply with a mismatched operation.

		 * We can sort this out by sending a lone sequence operation

		 * to the server on the same slot.

		 */

		if ((s32)(slot->seq_nr - slot->seq_nr_last_acked) > 1) {

			slot->seq_nr--;

			if (task->tk_msg.rpc_proc != &nfs4_procedures[NFSPROC4_CLNT_SEQUENCE]) {

				nfs4_probe_sequence(clp, task->tk_msg.rpc_cred, slot);

				res->sr_slot = NULL;

			}

			goto retry_nowait;

		}

		/*

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