Re: [PATCH 2/2] nfs41: Don't clear DRAINING flag on NFS4ERR_STALE_CLIENTID

[Trond Myklebust <Trond.Myklebust@netapp.com>]

On Sun, 2009-12-06 at 03:16 -0800, Ricardo Labiaga wrote: 
> If CREATE_SESSION fails with NFS4ERR_STALE_CLIENTID, don't clear the
> NFS4CLNT_SESSION_DRAINING flag and don't wake RPCs waiting for the
> session to be reestablished.  We don't have a session yet, so there
> is no reason to wake other RPCs.
> 
> This avoids sending spurious compounds with bogus sequenceID during
> session and state recovery.

How about the following instead? It ensures that we drain the session
before renewing the lease too.

Cheers
  Trond
--------------------------------------------------------------------------------------- 
nfs41: Don't clear DRAINING flag on NFS4ERR_STALE_CLIENTID

From: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>

If CREATE_SESSION fails with NFS4ERR_STALE_CLIENTID, don't clear the
NFS4CLNT_SESSION_DRAINING flag and don't wake RPCs waiting for the
session to be reestablished.  We don't have a session yet, so there
is no reason to wake other RPCs.

This avoids sending spurious compounds with bogus sequenceID during
session and state recovery.

Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
[Trond.Myklebust@netapp.com: cleaned up patch by adding the
                             nfs41_begin/end_drain_session() helpers]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---

 fs/nfs/nfs4proc.c  |    2 ++
 fs/nfs/nfs4state.c |   59 ++++++++++++++++++++++++++++++++++++----------------
 2 files changed, 43 insertions(+), 18 deletions(-)


diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 4be0369..fbae2c9 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4586,10 +4586,12 @@ struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
 	init_completion(&session->complete);
 
 	tbl = &session->fc_slot_table;
+	tbl->highest_used_slotid = -1;
 	spin_lock_init(&tbl->slot_tbl_lock);
 	rpc_init_wait_queue(&tbl->slot_tbl_waitq, "ForeChannel Slot table");
 
 	tbl = &session->bc_slot_table;
+	tbl->highest_used_slotid = -1;
 	spin_lock_init(&tbl->slot_tbl_lock);
 	rpc_init_wait_queue(&tbl->slot_tbl_waitq, "BackChannel Slot table");
 
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 9cfe686..1b629cc 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -135,16 +135,43 @@ static int nfs41_setup_state_renewal(struct nfs_client *clp)
 	return status;
 }
 
+static void nfs41_end_drain_session(struct nfs_client *clp,
+		struct nfs4_session *ses)
+{
+	if (test_and_clear_bit(NFS4CLNT_SESSION_DRAINING, &clp->cl_state))
+		rpc_wake_up(&ses->fc_slot_table.slot_tbl_waitq);
+}
+
+static int nfs41_begin_drain_session(struct nfs_client *clp,
+		struct nfs4_session *ses)
+{
+	struct nfs4_slot_table *tbl = &ses->fc_slot_table;
+
+	spin_lock(&tbl->slot_tbl_lock);
+	set_bit(NFS4CLNT_SESSION_DRAINING, &clp->cl_state);
+	if (tbl->highest_used_slotid != -1) {
+		INIT_COMPLETION(ses->complete);
+		spin_unlock(&tbl->slot_tbl_lock);
+		return wait_for_completion_interruptible(&ses->complete);
+	}
+	spin_unlock(&tbl->slot_tbl_lock);
+	return 0;
+}
+
 int nfs41_init_clientid(struct nfs_client *clp, struct rpc_cred *cred)
 {
 	int status;
 
+	status = nfs41_begin_drain_session(clp, clp->cl_session);
+	if (status != 0)
+		goto out;
 	status = nfs4_proc_exchange_id(clp, cred);
 	if (status != 0)
 		goto out;
 	status = nfs4_proc_create_session(clp);
 	if (status != 0)
 		goto out;
+	nfs41_end_drain_session(clp, clp->cl_session);
 	nfs41_setup_state_renewal(clp);
 	nfs_mark_client_ready(clp, NFS_CS_READY);
 out:
@@ -1239,20 +1266,11 @@ static void nfs4_session_recovery_handle_error(struct nfs_client *clp, int err)
 static int nfs4_reset_session(struct nfs_client *clp)
 {
 	struct nfs4_session *ses = clp->cl_session;
-	struct nfs4_slot_table *tbl = &ses->fc_slot_table;
 	int status;
 
-	spin_lock(&tbl->slot_tbl_lock);
-	set_bit(NFS4CLNT_SESSION_DRAINING, &clp->cl_state);
-	if (tbl->highest_used_slotid != -1) {
-		INIT_COMPLETION(ses->complete);
-		spin_unlock(&tbl->slot_tbl_lock);
-		status = wait_for_completion_interruptible(&ses->complete);
-		if (status) /* -ERESTARTSYS */
-			goto out;
-	} else {
-		spin_unlock(&tbl->slot_tbl_lock);
-	}
+	status = nfs41_begin_drain_session(clp, ses);
+	if (status != 0)
+		return status;
 
 	status = nfs4_proc_destroy_session(clp->cl_session);
 	if (status && status != -NFS4ERR_BADSESSION &&
@@ -1265,13 +1283,18 @@ static int nfs4_reset_session(struct nfs_client *clp)
 	status = nfs4_proc_create_session(clp);
 	if (status)
 		nfs4_session_recovery_handle_error(clp, status);
-		/* fall through*/
+
 out:
-	/* Wake up the next rpc task even on error */
-	clear_bit(NFS4CLNT_SESSION_DRAINING, &clp->cl_state);
-	rpc_wake_up(&clp->cl_session->fc_slot_table.slot_tbl_waitq);
-	if (status == 0)
-		nfs41_setup_state_renewal(clp);
+	/*
+	 * Let the state manager reestablish state
+	 * without waking other tasks yet.
+	 */
+	if (!test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state)) {
+		/* Wake up the next rpc task */
+		nfs41_end_drain_session(clp, ses);
+		if (status == 0)
+			nfs41_setup_state_renewal(clp);
+	}
 	return status;
 }