+ do_probe_callback(clp);
+}
+
+/*
+ * There's currently a single callback channel slot.
+ * If the slot is available, then mark it busy. Otherwise, set the
+ * thread for sleeping on the callback RPC wait queue.
+ */
+static int nfsd41_cb_setup_sequence(struct nfs4_client *clp,
+ struct rpc_task *task)
+{
+ struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
+ u32 *ptr = (u32 *)clp->cl_sessionid.data;
+ int status = 0;
+
+ dprintk("%s: %u:%u:%u:%u\n", __func__,
+ ptr[0], ptr[1], ptr[2], ptr[3]);
+
+ if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
+ rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
+ dprintk("%s slot is busy\n", __func__);
+ status = -EAGAIN;
+ goto out;
+ }
+
+ /*
+ * We'll need the clp during XDR encoding and decoding,
+ * and the sequence during decoding to verify the reply
+ */
+ args->args_seq.cbs_clp = clp;
+ task->tk_msg.rpc_resp = &args->args_seq;
+
+out:
+ dprintk("%s status=%d\n", __func__, status);
+ return status;
+}
+
+/*
+ * TODO: cb_sequence should support referring call lists, cachethis, multiple
+ * slots, and mark callback channel down on communication errors.
+ */
+static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
+{
+ struct nfs4_delegation *dp = calldata;
+ struct nfs4_client *clp = dp->dl_client;
+ struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
+ u32 minorversion = clp->cl_cb_conn.cb_minorversion;
+ int status = 0;
+
+ args->args_seq.cbs_minorversion = minorversion;
+ if (minorversion) {
+ status = nfsd41_cb_setup_sequence(clp, task);
+ if (status) {
+ if (status != -EAGAIN) {
+ /* terminate rpc task */
+ task->tk_status = status;
+ task->tk_action = NULL;
+ }
+ return;
+ }
+ }
+ rpc_call_start(task);
+}
+
+static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
+{
+ struct nfs4_delegation *dp = calldata;
+ struct nfs4_client *clp = dp->dl_client;
+
+ dprintk("%s: minorversion=%d\n", __func__,
+ clp->cl_cb_conn.cb_minorversion);
+
+ if (clp->cl_cb_conn.cb_minorversion) {
+ /* No need for lock, access serialized in nfsd4_cb_prepare */
+ ++clp->cl_cb_seq_nr;
+ clear_bit(0, &clp->cl_cb_slot_busy);
+ rpc_wake_up_next(&clp->cl_cb_waitq);
+ dprintk("%s: freed slot, new seqid=%d\n", __func__,
+ clp->cl_cb_seq_nr);
+
+ /* We're done looking into the sequence information */
+ task->tk_msg.rpc_resp = NULL;
+ }
+}
+
+static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata)
+{
+ struct nfs4_delegation *dp = calldata;
+ struct nfs4_client *clp = dp->dl_client;
+
+ nfsd4_cb_done(task, calldata);
+
+ switch (task->tk_status) {
+ case -EIO:
+ /* Network partition? */
+ atomic_set(&clp->cl_cb_conn.cb_set, 0);
+ warn_no_callback_path(clp, task->tk_status);
+ case -EBADHANDLE:
+ case -NFS4ERR_BAD_STATEID:
+ /* Race: client probably got cb_recall
+ * before open reply granting delegation */
+ break;
+ default:
+ /* success, or error we can't handle */
+ return;
+ }
+ if (dp->dl_retries--) {
+ rpc_delay(task, 2*HZ);
+ task->tk_status = 0;
+ rpc_restart_call(task);
+ return;
+ } else {
+ atomic_set(&clp->cl_cb_conn.cb_set, 0);
+ warn_no_callback_path(clp, task->tk_status);
+ }
+}