nfsd4: nfsd4_destroy_session must set callback client under the state lock

nfsd4_set_callback_client must be called under the state lock to atomically
set or unset the callback client and shutting down the previous one.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

2 files changed, 3 insertions, 0 deletions

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 1d5051d46b46..77bc9d3c80fd 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -718,6 +718,7 @@ void nfsd4_destroy_callback_queue(void)
         destroy_workqueue(callback_wq);
 }
 
+/* must be called under the state lock */
 void nfsd4_set_callback_client(struct nfs4_client *clp, struct rpc_clnt *new)
 {
         struct rpc_clnt *old = clp->cl_cb_client;
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index cc0e9117dd16..ede9dde52fe8 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1427,8 +1427,10 @@ nfsd4_destroy_session(struct svc_rqst *r,
         unhash_session(ses);
         spin_unlock(&client_lock);
 
+        nfs4_lock_state();
         /* wait for callbacks */
         nfsd4_set_callback_client(ses->se_client, NULL);
+        nfs4_unlock_state();
         nfsd4_put_session(ses);
         status = nfs_ok;
 out: