nfs41: renewd sequence operations should take/put client reference

renewd sends SEQUENCE requests to the NFS server in order to renew state.
As the request is asynchronous, renewd should take a reference to the
nfs_client to prevent concurrent umounts from freeing the session/client

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 12 insertions, 6 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 726bc195039d..663ae0c36834 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -419,7 +419,8 @@ static void nfs41_sequence_done(struct nfs_client *clp,
                         clp->cl_last_renewal = timestamp;
                 spin_unlock(&clp->cl_lock);
                 /* Check sequence flags */
-                nfs41_handle_sequence_flag_errors(clp, res->sr_status_flags);
+                if (atomic_read(&clp->cl_count) > 1)
+                        nfs41_handle_sequence_flag_errors(clp, res->sr_status_flags);
         }
 out:
         /* The session may be reset by one of the error handlers. */
@@ -5035,7 +5036,9 @@ static void nfs41_sequence_release(void *data)
 {
         struct nfs_client *clp = (struct nfs_client *)data;
 
-        nfs4_schedule_state_renewal(clp);
+        if (atomic_read(&clp->cl_count) > 1)
+                nfs4_schedule_state_renewal(clp);
+        nfs_put_client(clp);
 }
 
 static void nfs41_sequence_call_done(struct rpc_task *task, void *data)
@@ -5046,6 +5049,8 @@ static void nfs41_sequence_call_done(struct rpc_task *task, void *data)
 
         if (task->tk_status < 0) {
                 dprintk("%s ERROR %d\n", __func__, task->tk_status);
+                if (atomic_read(&clp->cl_count) == 1)
+                        goto out;
 
                 if (_nfs4_async_handle_error(task, NULL, clp, NULL)
                                                                 == -EAGAIN) {
@@ -5054,7 +5059,7 @@ static void nfs41_sequence_call_done(struct rpc_task *task, void *data)
                 }
         }
         dprintk("%s rpc_cred %p\n", __func__, task->tk_msg.rpc_cred);
-
+out:
         kfree(task->tk_msg.rpc_argp);
         kfree(task->tk_msg.rpc_resp);
 
@@ -5092,12 +5097,13 @@ static int nfs41_proc_async_sequence(struct nfs_client *clp,
                 .rpc_cred = cred,
         };
 
+        if (!atomic_inc_not_zero(&clp->cl_count))
+                return -EIO;
         args = kzalloc(sizeof(*args), GFP_KERNEL);
-        if (!args)
-                return -ENOMEM;
         res = kzalloc(sizeof(*res), GFP_KERNEL);
-        if (!res) {
+        if (!args || !res) {
                 kfree(args);
+                nfs_put_client(clp);
                 return -ENOMEM;
         }
         res->sr_slotid = NFS4_MAX_SLOT_TABLE;