lockd: Teach nlm_cmp_addr() to support AF_INET6 addresses

Update the nlm_cmp_addr() helper to support AF_INET6 as well as AF_INET
addresses.  New version takes two "struct sockaddr *" arguments instead of
"struct sockaddr_in *" arguments.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index b1dfa0b..ec8af11 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -12,6 +12,8 @@
 #ifdef __KERNEL__
 
 #include <linux/in.h>
+#include <linux/in6.h>
+#include <net/ipv6.h>
 #include <linux/fs.h>
 #include <linux/kref.h>
 #include <linux/utsname.h>
@@ -272,15 +274,41 @@
 	return file->f_file->f_path.dentry->d_inode;
 }
 
-/*
- * Compare two host addresses (needs modifying for ipv6)
- */
-static inline int nlm_cmp_addr(const struct sockaddr_in *sin1,
-			       const struct sockaddr_in *sin2)
+static inline int __nlm_cmp_addr4(const struct sockaddr *sap1,
+				  const struct sockaddr *sap2)
 {
+	const struct sockaddr_in *sin1 = (const struct sockaddr_in *)sap1;
+	const struct sockaddr_in *sin2 = (const struct sockaddr_in *)sap2;
 	return sin1->sin_addr.s_addr == sin2->sin_addr.s_addr;
 }
 
+static inline int __nlm_cmp_addr6(const struct sockaddr *sap1,
+				  const struct sockaddr *sap2)
+{
+	const struct sockaddr_in6 *sin1 = (const struct sockaddr_in6 *)sap1;
+	const struct sockaddr_in6 *sin2 = (const struct sockaddr_in6 *)sap2;
+	return ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr);
+}
+
+/*
+ * Compare two host addresses
+ *
+ * Return TRUE if the addresses are the same; otherwise FALSE.
+ */
+static inline int nlm_cmp_addr(const struct sockaddr *sap1,
+			       const struct sockaddr *sap2)
+{
+	if (sap1->sa_family == sap2->sa_family) {
+		switch (sap1->sa_family) {
+		case AF_INET:
+			return __nlm_cmp_addr4(sap1, sap2);
+		case AF_INET6:
+			return __nlm_cmp_addr6(sap1, sap2);
+		}
+	}
+	return 0;
+}
+
 /*
  * Compare two NLM locks.
  * When the second lock is of type F_UNLCK, this acts like a wildcard.