nfsd41: Backchannel: Setup sequence information

Follows the model used by the NFS client.  Setup the RPC prepare and done
function pointers so that we can populate the sequence information if
minorversion == 1.  rpc_run_task() is then invoked directly just like
existing NFS client operations do.

nfsd4_cb_prepare() determines if the sequence information needs to be setup.
If the slot is in use, it adds itself to the wait queue.

nfsd4_cb_done() wakes anyone sleeping on the callback channel wait queue
after our RPC reply has been received.  It also sets the task message
result pointer to NULL to clearly indicate we're done using it.

Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
[define and initialize cl_cb_seq_nr here]
[pulled out unused defintion of nfsd4_cb_done]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index f31175717c1a9f0d89573954b7c682e1bc6c8d1b..25a09069e4589a5604f78bc7d9b53bba197a3508 100644 (file)
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -501,6 +501,67 @@ nfsd4_probe_callback(struct nfs4_client *clp)
        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_recall_done(struct rpc_task *task, void *calldata)
 {
        struct nfs4_delegation *dp = calldata;
@@ -540,6 +601,7 @@ static void nfsd4_cb_recall_release(void *calldata)
 }
 
 static const struct rpc_call_ops nfsd4_cb_recall_ops = {
+       .rpc_call_prepare = nfsd4_cb_prepare,
        .rpc_call_done = nfsd4_cb_recall_done,
        .rpc_release = nfsd4_cb_recall_release,
 };

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index f4cebd9016bc3f77771517d317973a007eabdd3c..76b7bcbb3f2021634e8e8ffc77c9f208dc5f2416 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1331,6 +1331,7 @@ nfsd4_create_session(struct svc_rqst *rqstp,
                        unconf->cl_cb_conn.cb_minorversion =
                                cstate->minorversion;
                        unconf->cl_cb_conn.cb_prog = cr_ses->callback_prog;
+                       unconf->cl_cb_seq_nr = 1;
                        nfsd4_probe_callback(unconf);
                }
                conf = unconf;

diff --git a/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
index 9cc40a137c340edee76308235113ca5ded7f555a..b38d113241899df6da6464369e6c6a8f87e5bb5a 100644 (file)
--- a/include/linux/nfsd/state.h
+++ b/include/linux/nfsd/state.h
@@ -221,6 +221,7 @@ struct nfs4_client {
        /* for nfs41 callbacks */
        /* We currently support a single back channel with a single slot */
        unsigned long           cl_cb_slot_busy;
+       u32                     cl_cb_seq_nr;
        struct svc_xprt         *cl_cb_xprt;    /* 4.1 callback transport */
        struct rpc_wait_queue   cl_cb_waitq;    /* backchannel callers may */
                                                /* wait here for slots */