[Devel] [PATCH v2 02/12] NFS: callback service creation function introduced

[Stanislav Kinsbursky]

This function creates service if it's not exist, or increase usage counter of
the existent, and returns pointer to it.
Usage counter will be droppepd by svc_destroy() later in nfs_callback_up().

Signed-off-by: Stanislav Kinsbursky <skinsbursky at parallels.com>
---
 fs/nfs/callback.c |   55 +++++++++++++++++++++++++++++++++++++++++++----------
 1 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index f3d7ee2..b34ccc6 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -242,12 +242,46 @@ static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
 }
 #endif /* CONFIG_NFS_V4_1 */
 
+static struct svc_serv *nfs_callback_create_svc(int minorversion)
+{
+	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
+	struct svc_serv *serv;
+
+	/*
+	 * Check whether we're already up and running.
+	 */
+	if (cb_info->task) {
+		/*
+		 * Note: increase service usage, because later in case of error
+		 * svc_destroy() will be called.
+		 */
+		svc_get(cb_info->serv);
+		return cb_info->serv;
+	}
+
+	/*
+	 * Sanity check: if there's no task,
+	 * we should be the first user ...
+	 */
+	if (cb_info->users)
+		printk(KERN_WARNING "nfs_callback_up: no kthread, %d users??\n",
+			cb_info->users);
+
+	serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
+	if (!serv) {
+		printk(KERN_ERR "lockd_up: create service failed\n");
+		return ERR_PTR(-ENOMEM);
+	}
+	dprintk("nfs_callback_up: service created\n");
+	return serv;
+}
+
 /*
  * Bring up the callback thread if it is not already up.
  */
 int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 {
-	struct svc_serv *serv = NULL;
+	struct svc_serv *serv;
 	struct svc_rqst *rqstp;
 	int (*callback_svc)(void *vrqstp);
 	struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
@@ -257,15 +291,17 @@ int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 	struct net *net = current->nsproxy->net_ns;
 
 	mutex_lock(&nfs_callback_mutex);
+
+	serv = nfs_callback_create_svc(minorversion);
+	if (IS_ERR(serv)) {
+		ret = PTR_ERR(serv);
+		goto err_create;
+	}
+
 	if (cb_info->users++ || cb_info->task != NULL) {
 		nfs_callback_bc_serv(minorversion, xprt, cb_info);
 		goto out;
 	}
-	serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
-	if (!serv) {
-		ret = -ENOMEM;
-		goto out_err;
-	}
 
 	ret = svc_bind(serv, net);
 	if (ret < 0) {
@@ -306,16 +342,15 @@ out:
 	 * on both success and failure so that the refcount is 1 when the
 	 * thread exits.
 	 */
-	if (serv)
-		svc_destroy(serv);
+	svc_destroy(serv);
+err_create:
 	mutex_unlock(&nfs_callback_mutex);
 	return ret;
 out_err:
 	dprintk("NFS: Couldn't create callback socket or server thread; "
 		"err = %d\n", ret);
 	cb_info->users--;
-	if (serv)
-		svc_shutdown_net(serv, net);
+	svc_shutdown_net(serv, net);
 	goto out;
 }