nfsd4: use generic callback code in null case

This will eventually allow us, for example, to kick off null callback
from contexts where we can't sleep.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

3 files changed, 20 insertions, 15 deletions

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index a037f26252e..26fa878005c 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -519,7 +519,7 @@ static void warn_no_callback_path(struct nfs4_client *clp, int reason)
 
 static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
 {
-        struct nfs4_client *clp = calldata;
+        struct nfs4_client *clp = container_of(calldata, struct nfs4_client, cl_cb_null);
 
         if (task->tk_status)
                 warn_no_callback_path(clp, task->tk_status);
@@ -528,6 +528,8 @@ static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
 }
 
 static const struct rpc_call_ops nfsd4_cb_probe_ops = {
+        /* XXX: release method to ensure we set the cb channel down if
+         * necessary on early failure? */
         .rpc_call_done = nfsd4_cb_probe_done,
 };
 
@@ -543,21 +545,23 @@ int set_callback_cred(void)
         return 0;
 }
 
+static struct workqueue_struct *callback_wq;
 
 void do_probe_callback(struct nfs4_client *clp)
 {
-        struct rpc_message msg = {
-                .rpc_proc       = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_NULL],
-                .rpc_argp       = clp,
-                .rpc_cred       = callback_cred
-        };
-        int status;
+        struct nfsd4_callback *cb = &clp->cl_cb_null;
 
-        status = rpc_call_async(clp->cl_cb_client, &msg,
-                                RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
-                                &nfsd4_cb_probe_ops, (void *)clp);
-        if (status)
-                warn_no_callback_path(clp, status);
+        cb->cb_args.args_op = NULL;
+        cb->cb_args.args_clp = clp;
+
+        cb->cb_msg.rpc_proc = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_NULL];
+        cb->cb_msg.rpc_argp = NULL;
+        cb->cb_msg.rpc_resp = NULL;
+        cb->cb_msg.rpc_cred = callback_cred;
+
+        cb->cb_ops = &nfsd4_cb_probe_ops;
+
+        queue_work(callback_wq, &cb->cb_work);
 }
 
 /*
@@ -713,8 +717,6 @@ static const struct rpc_call_ops nfsd4_cb_recall_ops = {
         .rpc_release = nfsd4_cb_recall_release,
 };
 
-static struct workqueue_struct *callback_wq;
-
 int nfsd4_create_callback_queue(void)
 {
         callback_wq = create_singlethread_workqueue("nfsd4_callbacks");
@@ -760,7 +762,8 @@ void nfsd4_do_callback_rpc(struct work_struct *w)
                 nfsd4_release_cb(cb);
                 return; /* Client is shutting down; give up. */
         }
-        rpc_call_async(clnt, &cb->cb_msg, RPC_TASK_SOFT, cb->cb_ops, cb);
+        rpc_call_async(clnt, &cb->cb_msg, RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
+                        cb->cb_ops, cb);
 }
 
 void nfsd4_cb_recall(struct nfs4_delegation *dp)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index d347180ce55..2f464fb26af 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -978,6 +978,7 @@ static struct nfs4_client *create_client(struct xdr_netobj name, char *recdir,
         INIT_LIST_HEAD(&clp->cl_delegations);
         INIT_LIST_HEAD(&clp->cl_sessions);
         INIT_LIST_HEAD(&clp->cl_lru);
+        INIT_WORK(&clp->cl_cb_null.cb_work, nfsd4_do_callback_rpc);
         clp->cl_time = get_seconds();
         clear_bit(0, &clp->cl_cb_slot_busy);
         rpc_init_wait_queue(&clp->cl_cb_waitq, "Backchannel slot table");
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 6e592148ad8..19732d531cd 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -223,6 +223,7 @@ struct nfs4_client {
         struct nfs4_cb_conn     cl_cb_conn;
         struct rpc_clnt         *cl_cb_client;
         atomic_t                cl_cb_set;
+        struct nfsd4_callback   cl_cb_null;
 
         /* for nfs41 */
         struct list_head        cl_sessions;