lockd: Support AF_INET6 when hashing addresses in nlm_lookup_host

Adopt an approach similar to the RPC server's auth cache (from Aurelien
Charbon and Brian Haley).

Note nlm_lookup_host()'s existing IP address hash function has the same
issue with correctness on little-endian systems as the original IPv4 auth
cache hash function, so I've also updated it with a hash function similar
to the new auth cache hash function.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 43 insertions, 6 deletions

diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index dbf3fe620a0c..1f9d72a7a030 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -22,7 +22,6 @@
 
 #define NLMDBG_FACILITY         NLMDBG_HOSTCACHE
 #define NLM_HOST_NRHASH         32
-#define NLM_ADDRHASH(addr)      (ntohl(addr) & (NLM_HOST_NRHASH-1))
 #define NLM_HOST_REBIND         (60 * HZ)
 #define NLM_HOST_EXPIRE         (300 * HZ)
 #define NLM_HOST_COLLECT        (120 * HZ)
@@ -40,6 +39,48 @@ static struct nsm_handle *	nsm_find(const struct sockaddr_in *sin,
                                          const char *hostname,
                                          unsigned int hostname_len);
 
+/*
+ * Hash function must work well on big- and little-endian platforms
+ */
+static unsigned int __nlm_hash32(const __be32 n)
+{
+        unsigned int hash = (__force u32)n ^ ((__force u32)n >> 16);
+        return hash ^ (hash >> 8);
+}
+
+static unsigned int __nlm_hash_addr4(const struct sockaddr *sap)
+{
+        const struct sockaddr_in *sin = (struct sockaddr_in *)sap;
+        return __nlm_hash32(sin->sin_addr.s_addr);
+}
+
+static unsigned int __nlm_hash_addr6(const struct sockaddr *sap)
+{
+        const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
+        const struct in6_addr addr = sin6->sin6_addr;
+        return __nlm_hash32(addr.s6_addr32[0]) ^
+               __nlm_hash32(addr.s6_addr32[1]) ^
+               __nlm_hash32(addr.s6_addr32[2]) ^
+               __nlm_hash32(addr.s6_addr32[3]);
+}
+
+static unsigned int nlm_hash_address(const struct sockaddr *sap)
+{
+        unsigned int hash;
+
+        switch (sap->sa_family) {
+        case AF_INET:
+                hash = __nlm_hash_addr4(sap);
+                break;
+        case AF_INET6:
+                hash = __nlm_hash_addr6(sap);
+                break;
+        default:
+                hash = 0;
+        }
+        return hash & (NLM_HOST_NRHASH - 1);
+}
+
 static void nlm_clear_port(struct sockaddr *sap)
 {
         switch (sap->sa_family) {
@@ -92,16 +133,12 @@ static struct nlm_host *nlm_lookup_host(int server,
         struct hlist_node *pos;
         struct nlm_host *host;
         struct nsm_handle *nsm = NULL;
-        int             hash;
 
         dprintk("lockd: nlm_lookup_host(proto=%d, vers=%u,"
                         " my role is %s, hostname=%.*s)\n",
                         proto, version, server ? "server" : "client",
                         hostname_len, hostname ? hostname : "<none>");
 
-        hash = NLM_ADDRHASH(sin->sin_addr.s_addr);
-
-        /* Lock hash table */
         mutex_lock(&nlm_host_mutex);
 
         if (time_after_eq(jiffies, next_gc))
@@ -114,7 +151,7 @@ static struct nlm_host *nlm_lookup_host(int server,
          * different NLM rpc_clients into one single nlm_host object.
          * This would allow us to have one nlm_host per address.
          */
-        chain = &nlm_hosts[hash];
+        chain = &nlm_hosts[nlm_hash_address((struct sockaddr *)sin)];
         hlist_for_each_entry(host, pos, chain, h_hash) {
                 if (!nlm_cmp_addr(nlm_addr(host), (struct sockaddr *)sin))
                         continue;