> On Mar 4, 2022, at 7:37 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote:
>
> 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@xxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 52 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index b16f689f34c3..f42d72a8f5ca 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -1929,6 +1929,34 @@ __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)
> +{
> + clear_bit(NFSD4_CLIENT_RECONNECTED, &clp->cl_flags);
> + /* need to sync with thread resolving lock/deleg conflict */
> + spin_lock(&clp->cl_cs_lock);
> + 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 +2862,11 @@ 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 +2945,15 @@ 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;
> }
2983 static struct nfs4_client *
2984 find_unconfirmed_client_by_name(struct xdr_netobj *name, struct nfsd_net *nn)
2985 {
2986 lockdep_assert_held(&nn->client_lock);
2987 return find_clp_in_name_tree(name, &nn->unconf_name_tree);
2988 }
Notice the difference:
find_confirmed() does find_clp_in_name_tree(&nn->conf_name_tree);
^^^^
find_unconfirmed() does find_clp_in_name_tree(&nn->unconf_name_tree);
^^^^^^
I don't think we will ever find a client in unconf_name_tree that
has CLIENT_RECONNECTED set, will we? So it seems to me that you
can safely move the CLIENT_RECONNECTED test into
find_clp_in_name_tree() in all cases, maybe?
Or think about it this way: is it possible for an unconfirmed
client to become a courtesy client? I don't think it is.
> @@ -4032,12 +4070,19 @@ 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 +4113,11 @@ 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
>
--
Chuck Lever
