NFSv4.1: Ping server when our session table limits are too high

If the server requests a lower target_highest_slotid, then ensure
that we ping it with at least one RPC call containing an
appropriate SEQUENCE op. This ensures that the server won't need to
send a recall callback in order to shrink the slot table.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 23 insertions, 3 deletions

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 322bd0168ebf..8fe155ba16d1 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -321,6 +321,7 @@ int nfs41_discover_server_trunking(struct nfs_client *clp,
                         struct nfs_client **, struct rpc_cred *);
 extern void nfs4_schedule_session_recovery(struct nfs4_session *, int);
 extern void nfs41_server_notify_target_slotid_update(struct nfs_client *clp);
+extern void nfs41_server_notify_highest_slotid_update(struct nfs_client *clp);
 
 #else
 static inline void nfs4_schedule_session_recovery(struct nfs4_session *session, int err)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index a0c35ab12a6b..ecd4ed3a4f65 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -389,6 +389,7 @@ static void nfs41_sequence_free_slot(struct nfs4_sequence_res *res)
 {
         struct nfs4_session *session;
         struct nfs4_slot_table *tbl;
+        bool send_new_highest_used_slotid = false;
 
         if (!res->sr_slot) {
                 /* just wake up the next guy waiting since
@@ -400,12 +401,25 @@ static void nfs41_sequence_free_slot(struct nfs4_sequence_res *res)
         session = tbl->session;
 
         spin_lock(&tbl->slot_tbl_lock);
+        /* Be nice to the server: try to ensure that the last transmitted
+         * value for highest_user_slotid <= target_highest_slotid
+         */
+        if (tbl->highest_used_slotid > tbl->target_highest_slotid)
+                send_new_highest_used_slotid = true;
+
         nfs4_free_slot(tbl, res->sr_slot);
-        if (!nfs4_session_draining(session))
-                rpc_wake_up_first(&tbl->slot_tbl_waitq,
-                                nfs4_set_task_privileged, NULL);
+
+        if (tbl->highest_used_slotid != NFS4_NO_SLOT)
+                send_new_highest_used_slotid = false;
+        if (!nfs4_session_draining(session)) {
+                if (rpc_wake_up_first(&tbl->slot_tbl_waitq,
+                                nfs4_set_task_privileged, NULL) != NULL)
+                        send_new_highest_used_slotid = false;
+        }
         spin_unlock(&tbl->slot_tbl_lock);
         res->sr_slot = NULL;
+        if (send_new_highest_used_slotid)
+                nfs41_server_notify_highest_slotid_update(session->clp);
 }
 
 static int nfs41_sequence_done(struct rpc_task *task, struct nfs4_sequence_res *res)
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 1402283d152d..c137421f2123 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1961,6 +1961,11 @@ void nfs41_server_notify_target_slotid_update(struct nfs_client *clp)
         nfs41_ping_server(clp);
 }
 
+void nfs41_server_notify_highest_slotid_update(struct nfs_client *clp)
+{
+        nfs41_ping_server(clp);
+}
+
 static void nfs4_reset_all_state(struct nfs_client *clp)
 {
         if (test_and_set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) == 0) {