rxrpc: Provide a way for AFS to ask for the peer address of a call

Provide a function so that kernel users, such as AFS, can ask for the peer
address of a call:

   void rxrpc_kernel_get_peer(struct rxrpc_call *call,
			      struct sockaddr_rxrpc *_srx);

In the future the kernel service won't get sk_buffs to look inside.
Further, this allows us to hide any canonicalisation inside AF_RXRPC for
when IPv6 support is added.

Also propagate this through to afs_find_server() and issue a warning if we
can't handle the address family yet.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index df976b2a..d97552d 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -20,6 +20,7 @@
 #include <linux/sched.h>
 #include <linux/fscache.h>
 #include <linux/backing-dev.h>
+#include <net/af_rxrpc.h>
 
 #include "afs.h"
 #include "afs_vl.h"
@@ -607,6 +608,8 @@
 /*
  * rxrpc.c
  */
+extern struct socket *afs_socket;
+
 extern int afs_open_socket(void);
 extern void afs_close_socket(void);
 extern void afs_data_consumed(struct afs_call *, struct sk_buff *);
@@ -654,7 +657,7 @@
 
 extern struct afs_server *afs_lookup_server(struct afs_cell *,
 					    const struct in_addr *);
-extern struct afs_server *afs_find_server(const struct in_addr *);
+extern struct afs_server *afs_find_server(const struct sockaddr_rxrpc *);
 extern void afs_put_server(struct afs_server *);
 extern void __exit afs_purge_servers(void);