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From:   Dai Ngo <dai.ngo@oracle.com>
To:     chuck.lever@oracle.com, bfields@fieldses.org
Cc:     jlayton@redhat.com, viro@zeniv.linux.org.uk,
        linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH RFC v16 06/11] NFSD: Update find_clp_in_name_tree() to handle courtesy clients
Date:   Fri, 11 Mar 2022 18:13:30 -0800
Message-Id: <1647051215-2873-7-git-send-email-dai.ngo@oracle.com>
In-Reply-To: <1647051215-2873-1-git-send-email-dai.ngo@oracle.com>
References: <1647051215-2873-1-git-send-email-dai.ngo@oracle.com>
Precedence: bulk

Update find_clp_in_name_tree:
 . skip client with CLIENT_EXPIRED flag; discarded courtesy client.
 . if courtesy client was found then clear CLIENT_COURTESY and
   set CLIENT_RECONNECTED so callers can take appropriate action.

Update find_confirmed_client_by_name to discard the courtesy
client; set CLIENT_EXPIRED.

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

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 51 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index b16f689f34c3..2f19aaaf6a66 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1929,6 +1929,33 @@ __find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid, struct net *net)
 	return NULL;
 }
 
+static void
+nfsd4_discard_courtesy_clnt(struct nfs4_client *clp)
+{
+	spin_lock(&clp->cl_cs_lock);
+	set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
+	spin_unlock(&clp->cl_cs_lock);
+}
+
+static bool
+nfs4_is_courtesy_client_expired(struct nfs4_client *clp)
+{
+	spin_lock(&clp->cl_cs_lock);
+	clear_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags);
+	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags)) {
+		spin_unlock(&clp->cl_cs_lock);
+		return true;
+	}
+	/*
+	 * clear CLIENT_COURTESY flag to prevent it from being
+	 * destroyed by thread trying to resolve conflicts.
+	 */
+	if (test_and_clear_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
+		set_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags);
+	spin_unlock(&clp->cl_cs_lock);
+	return false;
+}
+
 static struct nfsd4_session *
 find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid, struct net *net,
 		__be32 *ret)
@@ -2834,8 +2861,11 @@ 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 (nfs4_is_courtesy_client_expired(clp))
+				return NULL;
 			return clp;
+		}
 	}
 	return NULL;
 }
@@ -2914,8 +2944,15 @@ 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 && test_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags)) {
+		nfsd4_discard_courtesy_clnt(clp);
+		clp = NULL;
+	}
+	return clp;
 }
 
 static struct nfs4_client *
@@ -4032,12 +4069,19 @@ 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 && test_bit(NFSD4_CLIENT_RECONNECTED, &conf->cl_flags)) {
+		cclient = conf;
+		conf = NULL;
+	}
+
 	if (conf && client_has_state(conf)) {
 		status = nfserr_clid_inuse;
 		if (clp_used_exchangeid(conf))
@@ -4068,7 +4112,11 @@ 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) {
-- 
2.9.5