cifs: teach signing routines how to deal with arrays of pages in a smb_rqst

Use the smb_send_rqst helper function to kmap each page in the array
and update the hash for that chunk.

Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/cifsproto.h

@@ -36,6 +36,8 @@ extern struct smb_hdr *cifs_buf_get(void);
 extern void cifs_buf_release(void *);
 extern struct smb_hdr *cifs_small_buf_get(void);
 extern void cifs_small_buf_release(void *);
+extern void cifs_rqst_page_to_kvec(struct smb_rqst *rqst, unsigned int idx,
+					struct kvec *iov);
 extern int smb_send(struct TCP_Server_Info *, struct smb_hdr *,
 			unsigned int /* length */);
 extern unsigned int _get_xid(void);