NFS: callback per-net usage counting introduced

This patch also introduces refcount-aware nfs_callback_down_net() wrapper for
svc_shutdown_net().

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 18 insertions, 2 deletions

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index baafa0f1e555..6dfdc8311f27 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -260,10 +260,25 @@ static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
         return 0;
 }
 
+static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
+{
+        struct nfs_net *nn = net_generic(net, nfs_net_id);
+
+        if (--nn->cb_users[minorversion])
+                return;
+
+        dprintk("NFS: destroy per-net callback data; net=%p\n", net);
+        svc_shutdown_net(serv, net);
+}
+
 static int nfs_callback_up_net(int minorversion, struct svc_serv *serv, struct net *net)
 {
+        struct nfs_net *nn = net_generic(net, nfs_net_id);
         int ret;
 
+        if (nn->cb_users[minorversion]++)
+                return 0;
+
         dprintk("NFS: create per-net callback data; net=%p\n", net);
 
         ret = svc_bind(serv, net);
@@ -378,7 +393,7 @@ err_create:
         return ret;
 
 err_start:
-        svc_shutdown_net(serv, net);
+        nfs_callback_down_net(minorversion, serv, net);
         dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
         goto err_net;
 }
@@ -391,10 +406,10 @@ void nfs_callback_down(int minorversion, struct net *net)
         struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
 
         mutex_lock(&nfs_callback_mutex);
+        nfs_callback_down_net(minorversion, cb_info->serv, net);
         cb_info->users--;
         if (cb_info->users == 0 && cb_info->task != NULL) {
                 kthread_stop(cb_info->task);
-                svc_shutdown_net(cb_info->serv, net);
                 svc_exit_thread(cb_info->rqst);
                 cb_info->serv = NULL;
                 cb_info->rqst = NULL;
diff --git a/fs/nfs/netns.h b/fs/nfs/netns.h
index 137238b012fb..b9c7f9b1f91b 100644
--- a/fs/nfs/netns.h
+++ b/fs/nfs/netns.h
@@ -24,6 +24,7 @@ struct nfs_net {
         struct idr cb_ident_idr; /* Protected by nfs_client_lock */
         unsigned short nfs_callback_tcpport;
         unsigned short nfs_callback_tcpport6;
+        int cb_users[NFS4_MAX_MINOR_VERSION + 1];
 #endif
         spinlock_t nfs_client_lock;
         struct timespec boot_time;