sunrpc: add IDs to multipath

This is used to uniquely identify sunrpc multipath objects in /sys.

Signed-off-by: Dan Aloni <dan@kernelim.com>

include/linux/sunrpc/xprtmultipath.h

@@ -14,6 +14,7 @@ struct rpc_xprt_switch {
 	spinlock_t		xps_lock;
 	struct kref		xps_kref;
 
+	unsigned int		xps_id;
 	unsigned int		xps_nxprts;
 	unsigned int		xps_nactive;
 	atomic_long_t		xps_queuelen;
@@ -71,4 +72,7 @@ extern struct rpc_xprt *xprt_iter_get_next(struct rpc_xprt_iter *xpi);
 
 extern bool rpc_xprt_switch_has_addr(struct rpc_xprt_switch *xps,
 		const struct sockaddr *sap);
+
+extern void xprt_multipath_cleanup_ids(void);
+
 #endif

net/sunrpc/sunrpc_syms.c

@@ -134,6 +134,7 @@ cleanup_sunrpc(void)
 	rpc_sysfs_exit();
 	rpc_cleanup_clids();
 	xprt_cleanup_ids();
+	xprt_multipath_cleanup_ids();
 	rpcauth_remove_module();
 	cleanup_socket_xprt();
 	svc_cleanup_xprt_sock();

net/sunrpc/xprtmultipath.c

@@ -86,6 +86,30 @@ void rpc_xprt_switch_remove_xprt(struct rpc_xprt_switch *xps,
 	xprt_put(xprt);
 }
 
+static DEFINE_IDA(rpc_xprtswitch_ids);
+
+void xprt_multipath_cleanup_ids(void)
+{
+	ida_destroy(&rpc_xprtswitch_ids);
+}
+
+static int xprt_switch_alloc_id(struct rpc_xprt_switch *xps)
+{
+	int id;
+
+	id = ida_simple_get(&rpc_xprtswitch_ids, 0, 0, GFP_KERNEL);
+	if (id < 0)
+		return id;
+
+	xps->xps_id = id;
+	return 0;
+}
+
+static void xprt_switch_free_id(struct rpc_xprt_switch *xps)
+{
+	ida_simple_remove(&rpc_xprtswitch_ids, xps->xps_id);
+}
+
 /**
  * xprt_switch_alloc - Allocate a new struct rpc_xprt_switch
  * @xprt: pointer to struct rpc_xprt
@@ -103,6 +127,7 @@ struct rpc_xprt_switch *xprt_switch_alloc(struct rpc_xprt *xprt,
 	if (xps != NULL) {
 		spin_lock_init(&xps->xps_lock);
 		kref_init(&xps->xps_kref);
+		xprt_switch_alloc_id(xps);
 		xps->xps_nxprts = xps->xps_nactive = 0;
 		atomic_long_set(&xps->xps_queuelen, 0);
 		xps->xps_net = NULL;
@@ -136,6 +161,7 @@ static void xprt_switch_free(struct kref *kref)
 			struct rpc_xprt_switch, xps_kref);
 
 	xprt_switch_free_entries(xps);
+	xprt_switch_free_id(xps);
 	kfree_rcu(xps, xps_rcu);
 }