netns: selective flush of rt_cache

dst cache is marked as expired on the per/namespace basis by previous
path. Right now we have to implement selective cache shrinking. This
procedure has been ported from older OpenVz codebase.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 67c3ed772c2741c564c7ba07c8092639acb4da7e..113cd2512ba7aebf363e51b5936a2b37ad00f2e1 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -699,6 +699,7 @@ static void rt_do_flush(int process_context)
 {
        unsigned int i;
        struct rtable *rth, *next;
+       struct rtable * tail;
 
        for (i = 0; i <= rt_hash_mask; i++) {
                if (process_context && need_resched())
@@ -708,11 +709,39 @@ static void rt_do_flush(int process_context)
                        continue;
 
                spin_lock_bh(rt_hash_lock_addr(i));
+#ifdef CONFIG_NET_NS
+               {
+               struct rtable ** prev, * p;
+
+               rth = rt_hash_table[i].chain;
+
+               /* defer releasing the head of the list after spin_unlock */
+               for (tail = rth; tail; tail = tail->u.dst.rt_next)
+                       if (!rt_is_expired(tail))
+                               break;
+               if (rth != tail)
+                       rt_hash_table[i].chain = tail;
+
+               /* call rt_free on entries after the tail requiring flush */
+               prev = &rt_hash_table[i].chain;
+               for (p = *prev; p; p = next) {
+                       next = p->u.dst.rt_next;
+                       if (!rt_is_expired(p)) {
+                               prev = &p->u.dst.rt_next;
+                       } else {
+                               *prev = next;
+                               rt_free(p);
+                       }
+               }
+               }
+#else
                rth = rt_hash_table[i].chain;
                rt_hash_table[i].chain = NULL;
+               tail = NULL;
+#endif
                spin_unlock_bh(rt_hash_lock_addr(i));
 
-               for (; rth; rth = next) {
+               for (; rth != tail; rth = next) {
                        next = rth->u.dst.rt_next;
                        rt_free(rth);
                }