nfsd41: Backchannel: Server backchannel RPC wait queue

RPC callback requests will wait on this wait queue if the backchannel
is out of slots.

Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

2 files changed, 6 insertions, 0 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index d8196b453f61..f4cebd9016bc 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -775,6 +775,8 @@ 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);
+        clear_bit(0, &clp->cl_cb_slot_busy);
+        rpc_init_wait_queue(&clp->cl_cb_waitq, "Backchannel slot table");
         return clp;
 }
 
diff --git a/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
index 0e5b5aecde03..9cc40a137c34 100644
--- a/include/linux/nfsd/state.h
+++ b/include/linux/nfsd/state.h
@@ -219,7 +219,11 @@ struct nfs4_client {
         struct nfs4_sessionid   cl_sessionid;
 
         /* for nfs41 callbacks */
+        /* We currently support a single back channel with a single slot */
+        unsigned long           cl_cb_slot_busy;
         struct svc_xprt         *cl_cb_xprt;    /* 4.1 callback transport */
+        struct rpc_wait_queue   cl_cb_waitq;    /* backchannel callers may */
+                                                /* wait here for slots */
 };
 
 /* struct nfs4_client_reset