Re: [PATCH RFC v17 06/11] NFSD: Update find_clp_in_name_tree() to handle courtesy client

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On 3/22/22 2:50 PM, J. Bruce Fields wrote:
On Thu, Mar 17, 2022 at 12:43:43AM -0700, Dai Ngo wrote:
Update find_clp_in_name_tree to check and expire courtesy client.

Update find_confirmed_client_by_name to discard the courtesy
client by setting CLIENT_EXPIRED.

Update nfsd4_setclientid to expire client with CLIENT_EXPIRED
state to prevent multiple confirmed clients with the same name
on the conf_id_hashtbl list.

This should be nn->conf_name_tree instead of conf_id_hashtbl list.

I could use a little more "why" here.

I'll give it another read, but right now I'm just not understanding how
this is meant to work.

Here is the problem description when running pynfs/nfs4.0 CID1 (need to
run CID5 first to create ton of clients) which requires the change in
nfsd4_setclientid to get the test to pass:

1st setclientid(name=clientA,verf=X)
  . find confirmed courtesy client with same name clientA (clientid:1) and
    mark it DESTROY and leave it on the confirmed list.
  . assign new clientA with clientid:2
  . put clientid:2 on unconfirmed list
  . return clientid:2

1st setclientid_confirm(clientid:2)
  . does not find any confirmed for clientid:2
  . find unconfirmed clientid:2
  . does not find any confirmed clientA (find_confirmed_client_by_name)
    since courtesy clientA was marked DESTROY
  . put clientid:2: to conf_name_tree list
PROBLEM: new clientA (clientid:2) and courtesy clientA (clientid:1)
    are both now on the conf_name_tree list.

clientid:2 does OPEN -> stidX
2nd setclientid(name=clientA, verf=Y)
  . does not find any confirmed clientA: skip courtesy clientA since it
    was marked DESTROY and does not find confirmed  client:2 due to the
    PROBLEM noted above; duplicate entry in binary tree.
  . create new clientid:3 and put it on unconfirmed list
  . return clientid:3

2nd setclientid_confirm(clientid:3)
  . does not find any confirmed clientid:3
  . find unconfirmed clientid:3
  . does not find any confirmed clientA: skip courtesy clientA since it
    was marked DESTROY and does not find confirmed client:2 due to the
    PROBLEM noted above; duplicate entry in binary tree.
  . put clientid:3 on conf_name_tree list

clientid:3 does CLOSE(stidX) -> NFS4_OK since clientid:2 still valid  <ERROR!>


-Dai


--b.

Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
---
  fs/nfsd/nfs4state.c | 27 ++++++++++++++++++++++++---
  fs/nfsd/state.h     | 22 ++++++++++++++++++++++
  2 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c6b5e05c9c34..dc0e60bf694c 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2834,8 +2834,11 @@ find_clp_in_name_tree(struct xdr_netobj *name, struct rb_root *root)
  			node = node->rb_left;
  		else if (cmp < 0)
  			node = node->rb_right;
-		else
+		else {
+			if (nfsd4_courtesy_clnt_expired(clp))
+				return NULL;
  			return clp;
+		}
  	}
  	return NULL;
  }
@@ -2914,8 +2917,15 @@ static bool clp_used_exchangeid(struct nfs4_client *clp)
  static struct nfs4_client *
  find_confirmed_client_by_name(struct xdr_netobj *name, struct nfsd_net *nn)
  {
+	struct nfs4_client *clp;
+
  	lockdep_assert_held(&nn->client_lock);
-	return find_clp_in_name_tree(name, &nn->conf_name_tree);
+	clp = find_clp_in_name_tree(name, &nn->conf_name_tree);
+	if (clp && clp->cl_cs_client_state == NFSD4_CLIENT_RECONNECTED) {
+		nfsd4_discard_courtesy_clnt(clp);
+		clp = NULL;
+	}
+	return clp;
  }
static struct nfs4_client *
@@ -4032,12 +4042,19 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
  	struct nfs4_client	*unconf = NULL;
  	__be32 			status;
  	struct nfsd_net		*nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+	struct nfs4_client	*cclient = NULL;
new = create_client(clname, rqstp, &clverifier);
  	if (new == NULL)
  		return nfserr_jukebox;
  	spin_lock(&nn->client_lock);
-	conf = find_confirmed_client_by_name(&clname, nn);
+	/* find confirmed client by name */
+	conf = find_clp_in_name_tree(&clname, &nn->conf_name_tree);
+	if (conf && conf->cl_cs_client_state == NFSD4_CLIENT_RECONNECTED) {
+		cclient = conf;
+		conf = NULL;
+	}
+
  	if (conf && client_has_state(conf)) {
  		status = nfserr_clid_inuse;
  		if (clp_used_exchangeid(conf))
@@ -4068,7 +4085,11 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
  	new = NULL;
  	status = nfs_ok;
  out:
+	if (cclient)
+		unhash_client_locked(cclient);
  	spin_unlock(&nn->client_lock);
+	if (cclient)
+		expire_client(cclient);
  	if (new)
  		free_client(new);
  	if (unconf) {
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index d156ae3ab46c..14b2c158ccca 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -735,6 +735,7 @@ extern void nfsd4_client_record_remove(struct nfs4_client *clp);
  extern int nfsd4_client_record_check(struct nfs4_client *clp);
  extern void nfsd4_record_grace_done(struct nfsd_net *nn);
+/* courteous server */
  static inline bool
  nfsd4_expire_courtesy_clnt(struct nfs4_client *clp)
  {
@@ -749,4 +750,25 @@ nfsd4_expire_courtesy_clnt(struct nfs4_client *clp)
  	return rc;
  }
+static inline void
+nfsd4_discard_courtesy_clnt(struct nfs4_client *clp)
+{
+	spin_lock(&clp->cl_cs_lock);
+	clp->cl_cs_client_state = NFSD4_CLIENT_EXPIRED;
+	spin_unlock(&clp->cl_cs_lock);
+}
+
+static inline bool
+nfsd4_courtesy_clnt_expired(struct nfs4_client *clp)
+{
+	bool rc = false;
+
+	spin_lock(&clp->cl_cs_lock);
+	if (clp->cl_cs_client_state == NFSD4_CLIENT_EXPIRED)
+		rc = true;
+	if (clp->cl_cs_client_state == NFSD4_CLIENT_COURTESY)
+		clp->cl_cs_client_state = NFSD4_CLIENT_RECONNECTED;
+	spin_unlock(&clp->cl_cs_lock);
+	return rc;
+}
  #endif   /* NFSD4_STATE_H */
--
2.9.5



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