cifs: avoid use of dstaddr as key for fscache client cookie

server->dstaddr can change when the DNS mapping for the
server hostname changes. But conn_id is a u64 counter
that is incremented each time a new TCP connection
is setup. So use only that as a key.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: sprasad-microsoft

fs/cifs/fscache.c

@@ -16,14 +16,6 @@
  * Key layout of CIFS server cache index object
  */
 struct cifs_server_key {
-	struct {
-		uint16_t	family;		/* address family */
-		__be16		port;		/* IP port */
-	} hdr;
-	union {
-		struct in_addr	ipv4_addr;
-		struct in6_addr	ipv6_addr;
-	};
 	__u64 conn_id;
 } __packed;
 
@@ -32,11 +24,7 @@ struct cifs_server_key {
  */
 void cifs_fscache_get_client_cookie(struct TCP_Server_Info *server)
 {
-	const struct sockaddr *sa = (struct sockaddr *) &server->dstaddr;
-	const struct sockaddr_in *addr = (struct sockaddr_in *) sa;
-	const struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *) sa;
 	struct cifs_server_key key;
-	uint16_t key_len = sizeof(key.hdr);
 
 	/*
 	 * Check if cookie was already initialized so don't reinitialize it.
@@ -47,36 +35,12 @@ void cifs_fscache_get_client_cookie(struct TCP_Server_Info *server)
 		return;
 
 	memset(&key, 0, sizeof(key));
-
-	/*
-	 * Should not be a problem as sin_family/sin6_family overlays
-	 * sa_family field
-	 */
-	key.hdr.family = sa->sa_family;
-	switch (sa->sa_family) {
-	case AF_INET:
-		key.hdr.port = addr->sin_port;
-		key.ipv4_addr = addr->sin_addr;
-		key_len += sizeof(key.ipv4_addr);
-		break;
-
-	case AF_INET6:
-		key.hdr.port = addr6->sin6_port;
-		key.ipv6_addr = addr6->sin6_addr;
-		key_len += sizeof(key.ipv6_addr);
-		break;
-
-	default:
-		cifs_dbg(VFS, "Unknown network family '%d'\n", sa->sa_family);
-		server->fscache = NULL;
-		return;
-	}
 	key.conn_id = server->conn_id;
 
 	server->fscache =
 		fscache_acquire_cookie(cifs_fscache_netfs.primary_index,
 				       &cifs_fscache_server_index_def,
-				       &key, key_len,
+				       &key, sizeof(key),
 				       NULL, 0,
 				       server, 0, true);
 	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",