nfsd: Ensure struct nfs4_client is unhashed before we try to destroy it

When we remove the client_mutex protection, we will need to ensure
that it can't be found by other threads while we're destroying it.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 33 insertions, 10 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 52ec47de1185..cb630db015b0 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1588,12 +1588,23 @@ free_client(struct nfs4_client *clp)
 }
 
 /* must be called under the client_lock */
-static inline void
+static void
 unhash_client_locked(struct nfs4_client *clp)
 {
+        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
         struct nfsd4_session *ses;
 
-        list_del(&clp->cl_lru);
+        /* Mark the client as expired! */
+        clp->cl_time = 0;
+        /* Make it invisible */
+        if (!list_empty(&clp->cl_idhash)) {
+                list_del_init(&clp->cl_idhash);
+                if (test_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags))
+                        rb_erase(&clp->cl_namenode, &nn->conf_name_tree);
+                else
+                        rb_erase(&clp->cl_namenode, &nn->unconf_name_tree);
+        }
+        list_del_init(&clp->cl_lru);
         spin_lock(&clp->cl_lock);
         list_for_each_entry(ses, &clp->cl_sessions, se_perclnt)
                 list_del_init(&ses->se_hash);
@@ -1601,7 +1612,17 @@ unhash_client_locked(struct nfs4_client *clp)
 }
 
 static void
-destroy_client(struct nfs4_client *clp)
+unhash_client(struct nfs4_client *clp)
+{
+        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+
+        spin_lock(&nn->client_lock);
+        unhash_client_locked(clp);
+        spin_unlock(&nn->client_lock);
+}
+
+static void
+__destroy_client(struct nfs4_client *clp)
 {
         struct nfs4_openowner *oo;
         struct nfs4_delegation *dp;
@@ -1634,22 +1655,24 @@ destroy_client(struct nfs4_client *clp)
         nfsd4_shutdown_callback(clp);
         if (clp->cl_cb_conn.cb_xprt)
                 svc_xprt_put(clp->cl_cb_conn.cb_xprt);
-        list_del(&clp->cl_idhash);
-        if (test_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags))
-                rb_erase(&clp->cl_namenode, &nn->conf_name_tree);
-        else
-                rb_erase(&clp->cl_namenode, &nn->unconf_name_tree);
         spin_lock(&nn->client_lock);
-        unhash_client_locked(clp);
         WARN_ON_ONCE(atomic_read(&clp->cl_refcount));
         free_client(clp);
         spin_unlock(&nn->client_lock);
 }
 
+static void
+destroy_client(struct nfs4_client *clp)
+{
+        unhash_client(clp);
+        __destroy_client(clp);
+}
+
 static void expire_client(struct nfs4_client *clp)
 {
+        unhash_client(clp);
         nfsd4_client_record_remove(clp);
-        destroy_client(clp);
+        __destroy_client(clp);
 }
 
 static void copy_verf(struct nfs4_client *target, nfs4_verifier *source)