cifs: Allow binding to local IP address.

When using multi-homed machines, it's nice to be able to specify
the local IP to use for outbound connections.  This patch gives
cifs the ability to bind to a particular IP address.

   Usage:  mount -t cifs -o srcaddr=192.168.1.50,user=foo, ...
   Usage:  mount -t cifs -o srcaddr=2002::100:1,user=foo, ...

Acked-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Dr. David Holder <david.holder@erion.co.uk>
Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index c68f31c..6ef0efa 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -139,6 +139,7 @@
 		struct sockaddr_in sockAddr;
 		struct sockaddr_in6 sockAddr6;
 	} addr;
+	struct sockaddr_storage srcaddr; /* locally bind to this IP */
 	wait_queue_head_t response_q;
 	wait_queue_head_t request_q; /* if more than maxmpx to srvr must block*/
 	struct list_head pending_mid_q;