NFS: Lockless DNS lookups

Enable RCU protected lookup in the legacy DNS resolver.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfs/dns_resolve.c b/fs/nfs/dns_resolve.c
index 060c658eab6600ebb0cf2dfa069d70d4e0f152a0..e93a5dc07c8c2c859a5d8633ff15c483cb56cbfb 100644 (file)
--- a/fs/nfs/dns_resolve.c
+++ b/fs/nfs/dns_resolve.c
@@ -65,6 +65,7 @@ struct nfs_dns_ent {
 
        struct sockaddr_storage addr;
        size_t addrlen;
+       struct rcu_head rcu_head;
 };
 
 
@@ -101,15 +102,23 @@ static void nfs_dns_ent_init(struct cache_head *cnew,
        }
 }
 
-static void nfs_dns_ent_put(struct kref *ref)
+static void nfs_dns_ent_free_rcu(struct rcu_head *head)
 {
        struct nfs_dns_ent *item;
 
-       item = container_of(ref, struct nfs_dns_ent, h.ref);
+       item = container_of(head, struct nfs_dns_ent, rcu_head);
        kfree(item->hostname);
        kfree(item);
 }
 
+static void nfs_dns_ent_put(struct kref *ref)
+{
+       struct nfs_dns_ent *item;
+
+       item = container_of(ref, struct nfs_dns_ent, h.ref);
+       call_rcu(item, nfs_dns_ent_free_rcu);
+}
+
 static struct cache_head *nfs_dns_ent_alloc(void)
 {
        struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);
@@ -195,7 +204,7 @@ static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
 {
        struct cache_head *ch;
 
-       ch = sunrpc_cache_lookup(cd,
+       ch = sunrpc_cache_lookup_rcu(cd,
                        &key->h,
                        nfs_dns_hash(key));
        if (!ch)