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.
Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@xxxxxxxxxx>
[define cl_cb_seq_nr here]
Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
---
fs/nfsd/nfs4callback.c | 78 ++++++++++++++++++++++++++++++++++++++++++++
include/linux/nfsd/state.h | 1 +
2 files changed, 79 insertions(+), 0 deletions(-)
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 0b5c4a6..b739cc9 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -533,6 +533,83 @@ 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;
+ struct nfs4_rpc_res *res = task->tk_msg.rpc_resp;
+ 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 */
+ args->args_seq.cbs_clp = clp;
+ res->res_seq = &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);
+ }
+}
+
static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata)
{
struct nfs4_delegation *dp = calldata;
@@ -572,6 +649,7 @@ 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/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
index 261cd73..9191497 100644
--- a/include/linux/nfsd/state.h
+++ b/include/linux/nfsd/state.h
@@ -198,6 +198,7 @@ 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 */
--
1.5.4.3
--
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