svc: Add svc API that queries for a transport instance

Add a new svc function that allows a service to query whether a
transport instance has already been created. This is used in lockd
to determine whether or not a transport needs to be created when
a lockd instance is brought up.

Specifying 0 for the address family or port is effectively a wild-card,
and will result in matching the first transport in the service's list
that has a matching class name.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Neil Brown <neilb@suse.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

3 files changed, 38 insertions, 14 deletions

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index a8e79a907202..470af0138bb5 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -219,18 +219,6 @@ lockd(struct svc_rqst *rqstp)
         module_put_and_exit(0);
 }
 
-static int find_xprt(struct svc_serv *serv, char *proto)
-{
-        struct svc_xprt *xprt;
-        int found = 0;
-        list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list)
-                if (strcmp(xprt->xpt_class->xcl_name, proto) == 0) {
-                        found = 1;
-                        break;
-                }
-        return found;
-}
-
 /*
  * Make any sockets that are needed but not present.
  * If nlm_udpport or nlm_tcpport were set as module
@@ -242,11 +230,11 @@ static int make_socks(struct svc_serv *serv, int proto)
         int err = 0;
 
         if (proto == IPPROTO_UDP || nlm_udpport)
-                if (!find_xprt(serv, "udp"))
+                if (!svc_find_xprt(serv, "udp", 0, 0))
                         err = svc_create_xprt(serv, "udp", nlm_udpport,
                                               SVC_SOCK_DEFAULTS);
         if (err >= 0 && (proto == IPPROTO_TCP || nlm_tcpport))
-                if (!find_xprt(serv, "tcp"))
+                if (!svc_find_xprt(serv, "tcp", 0, 0))
                         err = svc_create_xprt(serv, "tcp", nlm_tcpport,
                                               SVC_SOCK_DEFAULTS);
 
diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index 01e71b7a2e20..68862d51bb36 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -80,6 +80,7 @@ void	svc_close_xprt(struct svc_xprt *xprt);
 void    svc_delete_xprt(struct svc_xprt *xprt);
 int     svc_port_is_privileged(struct sockaddr *sin);
 int     svc_print_xprts(char *buf, int maxlen);
+struct  svc_xprt *svc_find_xprt(struct svc_serv *, char *, int, int);
 
 static inline void svc_xprt_get(struct svc_xprt *xprt)
 {
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 2e5b92ae24ed..512c10fc1a9f 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -977,3 +977,38 @@ static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt)
         spin_unlock(&xprt->xpt_lock);
         return dr;
 }
+
+/*
+ * Return the transport instance pointer for the endpoint accepting
+ * connections/peer traffic from the specified transport class,
+ * address family and port.
+ *
+ * Specifying 0 for the address family or port is effectively a
+ * wild-card, and will result in matching the first transport in the
+ * service's list that has a matching class name.
+ */
+struct svc_xprt *svc_find_xprt(struct svc_serv *serv, char *xcl_name,
+                               int af, int port)
+{
+        struct svc_xprt *xprt;
+        struct svc_xprt *found = NULL;
+
+        /* Sanity check the args */
+        if (!serv || !xcl_name)
+                return found;
+
+        spin_lock_bh(&serv->sv_lock);
+        list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list) {
+                if (strcmp(xprt->xpt_class->xcl_name, xcl_name))
+                        continue;
+                if (af != AF_UNSPEC && af != xprt->xpt_local.ss_family)
+                        continue;
+                if (port && port != svc_xprt_local_port(xprt))
+                        continue;
+                found = xprt;
+                break;
+        }
+        spin_unlock_bh(&serv->sv_lock);
+        return found;
+}
+EXPORT_SYMBOL_GPL(svc_find_xprt);