nfsd4: allow removing clients not holding state

RFC 5661 actually says we should allow an exchange_id to remove a
matching client, even if the exchange_id comes from a different
principal, *if* the victim client lacks any state.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 19 insertions, 2 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 491f13a70db1..5415550a63a9 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1508,6 +1508,19 @@ nfsd4_set_ex_flags(struct nfs4_client *new, struct nfsd4_exchange_id *clid)
         clid->flags = new->cl_exchange_flags;
 }
 
+static bool client_has_state(struct nfs4_client *clp)
+{
+        /*
+         * Note clp->cl_openowners check isn't quite right: there's no
+         * need to count owners without stateid's.
+         *
+         * Also note we should probably be using this in 4.0 case too.
+         */
+        return list_empty(&clp->cl_openowners)
+                && list_empty(&clp->cl_delegations)
+                && list_empty(&clp->cl_sessions);
+}
+
 __be32
 nfsd4_exchange_id(struct svc_rqst *rqstp,
                   struct nfsd4_compound_state *cstate,
@@ -1576,8 +1589,11 @@ nfsd4_exchange_id(struct svc_rqst *rqstp,
                         goto out_copy;
                 }
                 if (!creds_match) { /* case 3 */
-                        status = nfserr_clid_inuse;
-                        goto out;
+                        if (client_has_state(conf)) {
+                                status = nfserr_clid_inuse;
+                                goto out;
+                        }
+                        goto expire_client;
                 }
                 if (verfs_match) { /* case 2 */
                         exid->flags |= EXCHGID4_FLAG_CONFIRMED_R;
@@ -1585,6 +1601,7 @@ nfsd4_exchange_id(struct svc_rqst *rqstp,
                         goto out_copy;
                 }
                 /* case 5, client reboot */
+expire_client:
                 expire_client(conf);
                 goto out_new;
         }